JP2006227496A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus employing a direct transfer system and to provide an image forming apparatus that outputs a stable image of high resolution without producing an abnormal image when the apparatus is repeatedly used at high speed. <P>SOLUTION: The image forming apparatus employing a direct transfer system is characterized in that: an electrophotographic photoreceptor having at least a charge blocking layer, a moire preventing layer, a photosensitive layer and a protective layer, sequentially deposited on a conductive support is used as a photoreceptor; and the protective layer is formed by curing a radical polymerizable monomer of three or more functional groups having no charge transport structure and a monofunctional radical polymerizable compound having a charge transport structure. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an image forming apparatus employing a direct transfer method. Specifically, the image forming apparatus directly transfers the toner image formed on the electrophotographic photosensitive member to the transfer target, and the electrophotographic photosensitive member used in the image forming apparatus includes at least a charge blocking layer, a moire preventing layer, A protective layer formed by curing a photosensitive layer and at least a trifunctional or higher-functional radically polymerizable monomer having no charge transporting structure and a radically polymerizable compound having a monofunctional charge transporting structure is sequentially laminated. The present invention relates to an image forming apparatus that is an electrophotographic photosensitive member.

  In recent years, there has been a remarkable development of information processing system machines using electrophotography. In particular, an optical printer that converts information into a digital signal and records information by light has a remarkable improvement in print quality and reliability. This digital recording technique is applied not only to printers but also to ordinary copying machines, and so-called digital copying machines have been developed. In addition, since a variety of information processing functions are added to a conventional copying machine equipped with this digital recording technology for analog copying, the demand is expected to increase further in the future. Further, along with the spread of personal computers and the improvement in performance, the progress of digital color printers for performing color output of images and documents is also rapidly progressing.

  In recent years, the printers and copiers have been required to increase the speed and quality of the apparatus, including colorization. In an electrophotographic image forming apparatus, an electrostatic latent image is formed on a photoreceptor by charging and writing, and the electrostatic latent image is developed with toner and visualized. The toner image formed on the photoconductor is transferred to a transfer target (in most cases, a transfer paper), and the transferred toner image is fixed to fix the toner image on the transfer target. (Image) is formed and output.

  Among these several processes, there are several processes that affect the image quality improvement. One is the formation of an electrostatic latent image. The second is faithful development (formation of a toner image) for the electrostatic latent image. The third is faithful transfer of the toner image formed on the photoreceptor. The fourth is faithful fixing of the toner image transferred onto the transfer target. These “faithful” means how to transfer to the next process while maintaining the size of the formed electrostatic latent image or toner image.

  Regarding the formation of an electrostatic latent image, optical writing is performed on a uniformly charged photoconductor to form a potential contrast on the surface of the photoconductor. At this time, necessary techniques are uniformity of charging and formation of minute dots. As for the uniformity of charging, it is almost ensured by the device of the charging member and the uniformity of the film thickness of the photoreceptor. In addition, with regard to the formation of micro dots, the development of optical systems (writing elements, lenses, etc.) and the shortening of the oscillation wavelength of the elements themselves have made it possible to form micro beam systems. It is not.

  Regarding the development of the electrostatic latent image, in order to faithfully develop the electrostatic latent image formed on the photoconductor, a sufficient development potential is obtained by appropriately controlling the potential on the photoconductor and the developing bias, and the toner. It is necessary to sufficiently increase the chargeability of the toner itself and to use a sufficiently small developer (toner and carrier) in order to perform finer development. The development potential can be controlled at a level that does not cause an abnormal load on the photoreceptor, and the toner chargeability is also fully developed by developing toner materials (base resin and charge control agent). Has been. In addition, a carrier having a small particle diameter (50 μm or less), a toner having a small particle diameter (7 μm or less) and the like have been developed for high-definition development, and the development is not a rate-determining process for improving image quality at present.

  Regarding the transfer of the toner image, it is a step of transferring the toner image formed on the photosensitive member to the transfer target, but the toner originally transferred to the developing sleeve is transferred to the surface of the photosensitive member, The photosensitive member surface is connected by electrostatic attraction. Since this is transferred onto the transfer medium by the action of an electric field, the electric field applied here needs a considerably high electric field. At this time, if the transfer electric field strength is low, sufficient toner transfer is not performed, and transfer efficiency is lowered, and residual toner is generated on the photosensitive member, increasing the stress on the cleaning member. In addition, since the image density is reduced, more toner than necessary is used, which causes a problem of environmental load. In order to avoid this, the transfer electric field is set high, but the transfer electric field is basically applied by bias application by the transfer member, but if it is high, a discharge is generated between the transfer member and the surface of the photoreceptor. Cause an effect. This is because an ionization phenomenon occurs due to an electric field applied between the photosensitive member surface and the charging member. As a result, the toner image is transferred onto a transfer target that is originally disposed at a position directly opposite to the photoconductor, but the toner image is disturbed by this discharge phenomenon, and the rate of image quality is improved.

Regarding the fixing of the toner image, the toner is basically melted and fixed on the transfer target, which is a process of enlarging the toner image. However, by reducing the particle size of the toner and improving the color density, the amount of toner adhered per unit area (adhesion height) can be reduced, and more heat energy than necessary can be irradiated by advances in the fixing machine. Therefore, the spread or disturbance of the toner image due to fixing is small compared to the transfer process, and at present, it is not a rate-determining process for improving image quality.
As described above, at the present time, it is no exaggeration to say that the transfer process for transferring the toner image from the surface of the photoreceptor to the transfer target is the rate-determining process for the problem of high image quality.

  In an image forming apparatus that operates at high speed, from the intention of simplifying the machine design (basically reducing the number of parts) and the intention of reducing the number of transfer processes that generate toner image disturbance as described above, A method of directly transferring the toner image formed on the photosensitive member to a transfer target (transfer paper) is employed. In this method, the transfer object is conveyed by a belt, brought into contact with or close to the surface of the photoconductor, and a sufficient bias is applied from the back side of the transfer body, so that the toner is transferred from the surface of the photoconductor. The image is transferred to the transfer target. Usually, a member that conveys a transfer medium, such as a transfer conveyance belt, has a resistance close to conductivity, and a necessary electric field is applied from this member.

  In the operation of the image forming apparatus, when the transfer object is continuously sent out, it is almost impossible to carry the transfer object without any gap. Accordingly, a gap is formed between the transfer body and the transfer body, which is called between the sheets. When performing continuous printing, it is possible to operate with the bias applied to the transfer member. However, since a strong electric field acts on the photosensitive member between the sheets, the photosensitive member is extremely deteriorated. . For this reason, normally, the transfer bias is applied only when the transfer body is transported and only when the transfer body is covering (facing) the photoconductor.

  However, in the case of an extremely high-speed image forming apparatus, the process linear velocity (photosensitive linear velocity) is limited, and in order to increase the number of output sheets in a state close to existing ones, it is forced to narrow the gap between sheets as much as possible. . At the same time, a document created by a recent digital image system is required to print an output image of a computer or the like unlike a conventional document. In addition, there are originals in which writing is performed on the entire surface of the transfer object such as a full-color image, and it is necessary to apply a sufficient electric field to a position corresponding to the entire surface of the transfer object. In particular, in the case of a solid document, the image density of the trailing edge of the transfer paper may be lower even in the original development. ) It is necessary to apply a transfer bias. For this reason, a very high electric field acts on the photoconductor facing the both ends (outside) of the transferred body. This is because, in a normal state, the transfer electric field acts on the photoconductor via the transfer body, but there is no object that blocks the electric field at a place where the transfer body does not exist.

  Although the above-mentioned problem is in a direction to be solved by a technique that can take the timing of transferring the transfer object and applying the transfer bias very accurately, there are various forms of the transfer object and there are further problems. In general, in the image forming apparatus, the length of the photosensitive member in the longitudinal direction covers the maximum size of the transfer target that is output from the image forming apparatus. Therefore, in the case of an A3 compatible image forming apparatus, the image forming apparatus is designed with a length corresponding to the short side length of the A3 sheet. For this reason, when A4 is output, the surface of the photoconductor can be covered if image formation is performed based on the long side of A4. Is used for printing, the transfer bias is also applied to the outside of the transfer target, so that a strong electric field acts on the surface of the photoconductor.

As another form, there is a user who forms an image using a transfer medium having a punched hole in advance. In this case, a strong electric field partially acts on the surface of the photoreceptor regardless of the transfer timing.
The electrophotographic photosensitive member used in the image forming apparatus as described above may accelerate fatigue or cause dielectric breakdown due to the action of a strong transfer electric field. As a result, an image defect called background stain may occur in an image output from an image forming apparatus that has been used repeatedly for a long time.

In addition, there is a case where the charge having a bias polarity at the time of transfer remains on the photosensitive member and affects the next charging. When the charging process is started with residual charges remaining on the surface of the photoreceptor, the following problems occur.
In general, since the charging member of the high-speed image forming apparatus is charged only by the DC component, if the remaining charge remains, the charging of the portion becomes abnormal and uniform writing is performed on the entire surface. When such a document is printed, the surface potential is not constant, and density unevenness occurs during development. Depending on the polarity of the transfer bias, when a bias having the same polarity as the surface potential of the photoconductor is applied, the surface potential of the toner developing portion of the photoconductor becomes high, the charge removal by the charge removal member is not sufficient, and the charger has the ability. If it is small, the potential of this portion becomes high, and the history of the previous electrostatic latent image remains (positive afterimage, see FIG. 1).

  This is more serious when the polarity of the transfer bias is opposite to that of the photosensitive member. In the case of negative / positive development, which is currently the mainstream of digital machines, development is performed on the portion written on the photoconductor, so that the developed portion has a low surface potential. Since a reverse polarity bias is applied here, the surface potential of this portion is charged to a polarity opposite to the original charged polarity of the photoreceptor. As described above, in the case of a high potential with the same polarity, the potential can be canceled by sufficiently performing the photostatic charge, but when the reverse polarity is applied, this is canceled by the photostatic charge. I can't do that. This is because current photoconductors generate carriers and can only be transported on one side (usually only holes). As a result, the charging ability is insufficient at the time of charging in the next process, and the photosensitive member of this part is not sufficiently charged, leaving a history of the electrostatic latent image of the previous time (negative afterimage, FIG. 2).

  In order to avoid these problems, there is a method using a charging member that superimposes the AC component. However, when high-speed charging is required, the frequency of the AC component must be increased according to the linear velocity of the photosensitive member. Not only will the load on the members or the power supply increase, but the chemical hazard on the surface of the photoconductor will increase, resulting in a fatal problem for high durability that promotes photoconductor wear.

This is not the only cause of negatives, but also occurs when the photoconductor is heavily fatigued and enters the charging process with a uniform surface charge after static elimination, especially when the same document is output repeatedly or in a fixed format. When the same manuscript exists at a location (for example, when it is a business manuscript and a company logo mark or the like is present at the same location), it becomes a significant problem.
As described above, the usage of the high-speed image forming apparatus is very diverse including the case where it is colored, and in order to cope with this, the state of the image forming system is always maintained in the same state. In order to realize this concretely, it is all about how to keep the photoconductor in the same state (maintain the initial state) in order to always produce the electrostatic latent image in the same manner.

With current technology, it is very difficult to control the phenomenon of reverse polarity charging, either transfer with reduced transfer capability or charging under strong charging conditions so that no previous history remains. There is only a way. The former is to surely reduce the transfer efficiency and is not allowed for high image quality. Therefore, there is only a method for dealing with the current situation in which the output from the charger is increased.
When such a method is used, a low-pressure-resistant photoconductor may cause dielectric breakdown as described above, or may generate an abnormal image called scumming. To prevent this, a photoconductor that is resistant to scumming is used. I need it.

  Such a digital image forming apparatus is required to improve its function year by year, as well as to have high image quality as well as high durability and high stability. Furthermore, in order to achieve high-speed color, a tandem system using a plurality of image forming elements each having one member necessary for image formation such as charging, exposure, development, cleaning, charge removal, etc. attached to one photoconductor. Color image forming apparatuses are currently mainstream. This is usually equipped with image forming elements for yellow, magenta, cyan, and black, and each toner image is produced in parallel with four image forming elements and overlapped on a transfer body (transfer paper) or an intermediate transfer body. Thus, a color image is produced at high speed. For this reason, unless the photosensitive member and the members around it are made compact, the image forming apparatus becomes very large. Therefore, it is essential to reduce the diameter of the photosensitive member arranged at the center of the image forming element. . Even if the image forming apparatus is made compact by reducing the diameter of the photosensitive member, there is no merit of reducing the diameter when the life is extremely shortened compared to the case of a large diameter. For this reason, it is an issue of this technique to extend the life of the photoconductor as compared to the conventional photoconductor.

  There are two rate-determining processes in the life of the photoreceptor, one is electrostatic fatigue, and the other is surface layer wear. Both are major problems for the current mainstream organic photoreceptors. The former is a change in the surface potential (charge potential and exposed portion potential) of the photoreceptor during repeated use in image formation such as charging and exposure. When organic materials are used, the charged potential decreases or the exposed portion potential increases. (Sometimes called residual potential) is a problem. The latter is a phenomenon in which a layer located on the outermost surface constituting the photosensitive member is mechanically worn by sliding of a cleaning member or the like. When the film thickness of the photoreceptor surface layer decreases due to this wear, scratches on the surface, an increase in electric field strength due to a decrease in the film thickness of the photoreceptor layer, acceleration of electrostatic fatigue, and the like are caused, and the life of the photoreceptor is significantly reduced. It becomes a factor. Therefore, in order to improve the life of the photoreceptor, the above two problems must be solved at the same time.

  At present, electrophotographic image forming apparatuses are entering the printing field by realizing high speed, and high image quality and high stability are demanded. Regarding the former, 600 dpi is the lowest quality as the resolution in image writing, and the resolution has been greatly improved. In the latter, taking advantage of the characteristics of electrophotography that can directly print manuscript information, it is possible to add various information that is different one by one to a part of an output manuscript that is good at mass printing. In addition, a large variety of writing and developing operations are performed, in which slightly different information is input one by one at the same time, and stability as a system has been greatly demanded. For these, stability in repeated use of the image forming element is naturally required, and it is extremely important that no abnormal image is generated.

  The life and stability of such an image forming apparatus is the center of image formation, and a photoreceptor that always performs an associated operation with other members during an image forming operation holds the most important key. With all the energetic development of the photoreceptor so far, several techniques are being completed regarding the electrostatic properties and surface wear of the photoreceptor. For example, with regard to improvement of electrostatic characteristics, development of a charge generation material having a high photocarrier generation efficiency and development of a charge transport material having a high mobility can be mentioned. By combining these, it is possible to obtain a large gain and response in light attenuation. As a whole system, the charging potential is reduced, the amount of writing light is reduced, the development bias is reduced, the transfer bias is reduced, and the static elimination process is reduced. It creates unnecessaryness and creates a margin in system design. All of these lead to a reduction in the hazard applied to the photoreceptor, and allowance is also created in the photoreceptor itself.

  In addition, as described above, the usage of the photoconductor in the analog image forming apparatus and the monochrome image forming apparatus is changed by the advent of a high-speed full-color machine, and various ways of optical writing are used. It became so. In such a case, the biggest problem is that the cause of the abnormal image is the photoconductor. Although there are various cases of occurrence of abnormal images, they can be roughly divided into two. One is an abnormal image due to scratches generated on the surface of the photoreceptor, and the other is an abnormal image caused by electrostatic fatigue of the photoreceptor. The former can be dealt with considerably by improving the surface layer of the photosensitive member (for example, using a protective layer) or by improving the photosensitive member abutting member. The latter is due to the deterioration of the photoconductor itself, but the biggest problem at present is background stain in negative / positive development (a phenomenon in which black spots and black spots occur on the background of the image). It is.

  Causes of scumming are dirt and defects on the conductive support, electrical breakdown of the photosensitive layer, carrier (charge) injection from the support, increased dark decay of the photosensitive member, and generation of thermal carriers in the photosensitive layer. Is mentioned. Of these, the contamination and defects of the support can be dealt with by eliminating such support before applying the photosensitive layer, and in a sense, it is caused by an error. is not. Therefore, improving the withstand voltage of the photoreceptor, the charge injection from the support, and the reduction in electrostatic fatigue is considered to be the fundamental solution to this problem.

As a conventional technique related to the injection of electric charges from a conductive support, which is one of the causes of background contamination, a technique of providing an undercoat layer or an intermediate layer between the conductive support and the photosensitive layer has been proposed.
For example, Patent Document 1 discloses a cellulose nitrate resin intermediate layer, Patent Document 2 includes a nylon resin intermediate layer, Patent Document 3 includes a maleic acid resin intermediate layer, and Patent Document 4 includes a polyvinyl alcohol resin intermediate layer. Are each disclosed. However, since these single layers and the intermediate layer of the resin alone have high electric resistance, the residual potential is increased, and the image density is lowered in negative / positive development. In addition, since it exhibits ionic conductivity due to impurities and the like, the electrical resistance of the intermediate layer is particularly high in a low temperature and low humidity environment, so the residual potential is significantly increased, and the electrical resistance of the intermediate layer is high in a high temperature and high humidity environment. There was a tendency to decrease and to easily cause scumming. For this reason, in order to reduce the residual potential, it is necessary to reduce the thickness of the intermediate layer, and it has been a fact that sufficient suppression of background contamination has not been realized.

  In order to solve these problems, as a technique for controlling the electric resistance of the intermediate layer, a method of adding a conductive additive to the bulk of the intermediate layer has been proposed. For example, Patent Document 5 includes an intermediate layer in which a carbon or chalcogen-based material is dispersed in a curable resin, and Patent Document 6 includes a thermal polymer intermediate layer using an isocyanate-based curing agent to which a quaternary ammonium salt is added, Patent Document 7 discloses a resin intermediate layer to which a resistance modifier is added, and Patent Document 8 discloses a resin intermediate layer to which an organometallic compound is added. However, these resin intermediate layers alone tend to increase scumming even when the residual potential is reduced, and in recent image forming apparatuses using coherent light such as laser light, moire images are displayed. It has the problem that it occurs.

  Furthermore, for the purpose of simultaneously controlling the moiré prevention and the electric resistance of the intermediate layer, a photoreceptor containing a filler in the intermediate layer has been proposed. For example, Patent Document 9 includes a resin intermediate layer in which an oxide of aluminum or tin is dispersed, Patent Document 10 includes a resin intermediate layer in which conductive particles are dispersed, and Patent Document 11 includes an intermediate layer in which magnetite is dispersed. Patent Document 12 discloses a resin intermediate layer in which titanium oxide and tin oxide are dispersed. Patent Document 13, Patent Document 14, Patent Document 15, Patent Document 16, Patent Document 17, and Patent Document 18 include calcium, magnesium, aluminum, and the like. An intermediate layer of a resin in which powders of boride, nitride, fluoride, and oxide are dispersed is disclosed. In the intermediate layer in which fillers are dispersed, it is preferable to increase the filler amount to reduce the residual potential, and it is preferable to reduce the filler amount in order to suppress background contamination. It was difficult to do. In addition, if the resin content decreases, the adhesiveness with the conductive support decreases, and there is a problem that peeling easily occurs. Was fatal.

  In order to solve such problems, a concept of stacking intermediate layers has been proposed. The laminated structure is roughly classified into two types. One is a resin layer (202) in which filler is dispersed on a conductive support (201), a resin layer (203) in which filler is not dispersed, and a photosensitive layer (204). (Refer to FIG. 3), and the other is a resin layer (203) in which filler is not dispersed on a conductive support (201), a resin layer (202) in which filler is dispersed, and a photosensitive layer (204). ) In order (see FIG. 4).

  To elaborate the former configuration, in order to conceal the defects of the support as described above, a conductive filler dispersion layer in which a low-resistance filler is dispersed is provided on the conductive support, and the resin layer is provided thereon. It is provided. These are described in, for example, Patent Literature 19, Patent Literature 20, Patent Literature 21, Patent Literature 22, Patent Literature 23, Patent Literature 24, Patent Literature 25, Patent Literature 26, Patent Literature 27, and the like. This configuration can prevent the occurrence of moire by the filler dispersion layer containing the conductive filler, and since it has a resin layer on it, it can also have a soiling suppression effect. Since it is only the resin layer that suppresses carrier injection from the conductive support, as in the case where the above resin layer is used alone, if the film thickness is increased, the residual potential increases significantly. This would cause an increase in soiling, which was not fully satisfactory for achieving both. In addition, an insulating resin layer is laminated on the filler dispersion layer, and the filler dispersion layer needs to be thick (10 μm or more) in order to conceal defects in the conductive support. Even if it is intended to increase the resistance of the filler contained in the layer to suppress the soiling, it is difficult because the influence of the residual potential is remarkably increased.

  Patent Document 28, Patent Document 29, and Patent Document 30 disclose a photoreceptor in which a conductive layer, an intermediate layer, and a photosensitive layer containing a titanyl phthalocyanine crystal are stacked. However, it is difficult to sufficiently suppress the influence of soiling by simply laminating the conductive layer and the intermediate layer. This is because, in addition to the above reasons, there are cases where the generation of thermal carriers in the photosensitive layer becomes a cause of background contamination.

  On the other hand, as the latter configuration, a resin layer for suppressing carrier injection is provided on a conductive support, and a filler dispersion layer containing a filler is provided thereon. For example, Patent Document 31, Patent Document 32, etc. It is described in. In this configuration, the carrier injection can be suppressed by the resin layer, but the filler dispersion layer containing the filler laminated on the resin layer has little influence on the residual potential even if it does not contain a conductive filler. The effect of suppressing the injection is enhanced, and the effectiveness is higher than the former configuration in achieving both residual potential and soiling.

  As described above, the structure in which a plurality of intermediate layers are stacked and separated into functions exhibits high effectiveness in achieving both moire prevention, background stain suppression, and residual potential reduction, but it is necessary to use the resin layer in a thin film. Depending on the resin used there, there is a tendency that the soil dependency and the residual potential are highly dependent on the humidity and the dependency on the film thickness is increased, and the stability is not necessarily high.

  Also disclosed is a method using an undercoat layer or an intermediate layer containing N-alkoxy (methoxy) methylated nylon. For example, Patent Document 33 discloses a method in which an undercoating layer contains an alkoxymethylated copolymer nylon having an alkoxymethylation degree of 5 to 30%, and Patent Document 34 discloses that an intermediate layer is crosslinked as an inorganic pigment and a binder resin. According to Patent Document 35, the undercoat layer is made of N-alkoxymethylated nylon resin, and the elemental concentrations of impurities Na, Ca and P atoms contained in the resin are 10 ppm each. The method described below is a method in which Patent Document 36 includes an N-alkoxymethylated polyamide copolymer containing λ-amino-n-lauric acid as a main component in the intermediate layer. A method of containing a polyamide resin having a unit component having a certain structure is disclosed.

  As described above, methods for laminating an undercoat layer or an intermediate layer and for containing N-alkoxymethylated nylon in the undercoat layer or the intermediate layer are well known, and suppress the injection of charges from the conductive support. It is effective as a means for enhancing the dirt suppression effect. However, as the electric field strength increases as the photoconductor wears, the scumming increases remarkably. Even at high electric field strength, attempts to enhance the charge blocking function of the undercoat layer or the intermediate layer cause a significant increase in residual potential. However, merely suppressing the injection of electric charges from the conductive support by the undercoat layer or the intermediate layer is not sufficient for suppressing the soiling in the repeated use of the photoconductor, and high durability of the photoconductor has been realized. There wasn't.

  In addition, since the frequency of outputting images has increased significantly, it has become an important issue to improve the image quality of the apparatus. In order to achieve high image quality, (i) an electrostatic latent image on the photosensitive member formed by the charging unit and exposure unit is formed as a high-density image, and (ii) a subsequent developing unit There are three problems: to form a toner image faithfully to the electrostatic latent image, and (iii) to accurately transfer the toner image on the photoconductor to the transfer paper. Means for solving these problems include (i) a method of forming an electrostatic latent image by high-density writing using a small-diameter beam as an exposure means. Optical carriers generated in the layer spread due to Coulomb repulsion, and dots having a size corresponding to the beam diameter cannot be formed. (Ii) There is a method of forming a toner image faithful to the electrostatic latent image on the photosensitive member by reducing the toner particle size in the developing means. And no aggregation is performed, and scattered dots are formed with respect to the dots of the electrostatic latent image. (Iii) There is a method of increasing the transfer efficiency by increasing the gap electric field strength in the transfer means and faithfully transferring the toner image on the photosensitive member to the transfer paper. In some cases, transfer dust may occur and fatigue of the electrical characteristics of the photoreceptor may be promoted.

  FIG. 5 shows how dots are formed with respect to the electric field strength (photoconductor surface potential / photosensitive layer thickness) applied to the photoconductor (writing is performed at 1200 dpi). As shown in FIG. 5, in order to faithfully reproduce the small-diameter dots, the electric field strength needs to be set higher. FIG. 6 shows changes in the soiling rank with respect to the electric field strength. The background dirt rank referred to here indicates the degree of background dirt, and the greater the numerical value, the better the degree of background dirt (the less frequently the background dirt is generated). As can be seen from FIGS. 5 and 6, there is a trade-off relationship between the two in terms of electric field strength. In order to avoid scumming, a system is generally used in which the electric field strength of the photoconductor is 30 V / μm or less, and the reproduction of small-diameter dots is somewhat sacrificed. For example, in Patent Document 38, there is a description that the electric field strength of the photosensitive member is used at 12 to 40 V / μm in order to achieve both reproducibility of background contamination and fine lines.

  However, when the resolution of the writing light is increased, the writing dots cannot be developed with good reproducibility unless this lower limit is set higher. In addition, the upper limit value of the electric field strength varies depending on the material (mainly charge generation material) constituting the photoconductor as to the soiling of the photoconductor. Such a problem is a phenomenon that does not cause much problem with low-resolution (400 dpi or less) writing light, but is a problem that appears prominently in recent high-resolution writing (600 dpi or more, finer writing is 1200 dpi or more). is there.

  In the prior art, when the soiling is suppressed, the residual potential increase and the environmental dependency are remarkably increased, and when the residual potential increase is suppressed, the soiling suppression effect becomes insufficient, and both of them are not realized. It was. As described above, the background contamination includes many factors such as the influence of coarse particles or impurities of the charge generation material contained in the photosensitive layer or the charge generation layer as well as the influence due to the charge injection from the conductive support. However, another important factor that greatly affects the background contamination is an increase in electric field strength due to a decrease in the film thickness of the photoreceptor.

  In order to cope with an increase in electric field strength, the charge transport layer or protective layer formed on the outermost surface of the photoreceptor has been devised to increase the wear resistance. Techniques for improving the abrasion resistance of the photosensitive layer include (i) using a curable binder in the crosslinkable charge transport layer (see, for example, Patent Document 39), and (ii) using a polymer charge transport material. (For example, see Patent Document 40), (iii) those in which an inorganic filler is dispersed in a cross-linked charge transport layer (for example, see Patent Document 41), and the like. As described above, since the fluctuation of the electric field strength with time can be reduced by increasing the wear resistance of the photoreceptor, a high effect can be obtained for the suppression of background contamination.

  However, among these technologies, those using the curable binder (i) have a poor residual potential due to poor compatibility with the charge transport material and impurities such as polymerization initiators and unreacted residues. There is a tendency for image density reduction to occur easily. In addition, although the polymer type charge transport material (ii) can improve the abrasion resistance to some extent, the durability required for the organic photoreceptor is not fully satisfied. Not reached. In addition, polymer charge transport materials are difficult to polymerize and purify, and it is difficult to obtain a high-purity material. Therefore, it is difficult to stabilize electrical characteristics between materials. Furthermore, production problems such as high viscosity of the coating solution may occur. The dispersion of the inorganic filler (iii) exhibits higher abrasion resistance than a photoreceptor in which a normal low molecular charge transport material is dispersed in an inert polymer, but the charge present on the surface of the inorganic filler. The residual potential increases due to the trap, and the image density tends to decrease. In addition, when the unevenness of the inorganic filler and the binder resin on the surface of the photoconductor is large, defective cleaning may occur, which may cause toner filming and image flow. These technologies (i), (ii), and (iii) have defects in residual potential, cleanability, etc., even if they are effective in suppressing scumming. I haven't fully satisfied.

In particular, in recent years, small-diameter toner having a small toner particle diameter and a spherical toner having a uniform particle diameter distribution and a nearly spherical shape have been used to improve image quality. Such toner is difficult to be cleaned by a blade cleaning method used in a conventional image forming apparatus, and is liable to cause a cleaning defect such as toner slipping through the blade. In addition, various additives are added to the toner in order to improve its function, and filming and the like based on this additive are also likely to occur.
Such a defect is likely to appear remarkably when the abrasion resistance of the surface layer of the photoreceptor is improved. This is presumably due to the fact that the blade cleaning has cleaned the toner while the surface layer of the photoconductor is worn (scraped off). This is considered to be caused by this.

  In this regard, the change in the surface property of the photoreceptor surface layer after repeated use from the unused state of the photoreceptor is a major cause. That is, although a technique for reducing the wear amount of the surface layer of the photoreceptor has been proposed, the wear amount itself is expressed in the form of the average value of the surface layer. It is considered that there are irregularities (for example, very fine streaks, fine irregularities due to the addition of filler, etc.), and the contact state with the blade changes greatly after repeated use. For this reason, when improving the wear resistance of the surface layer as described above, in addition to reducing the amount of wear, it is required that the change in the surface shape is small (of course, the surface is very smooth in the initial state). Is essential). However, no technology up to that point has been proposed in the development of the surface layer so far.

  Furthermore, a photoreceptor containing a polyfunctional acrylate monomer cured product for improving the abrasion resistance and scratch resistance of (i) is also known (see Patent Document 42). However, in this photoreceptor, although there is a description that the polyfunctional acrylate monomer cured product is contained in the protective layer provided on the photosensitive layer, the protective layer may contain a charge transport material. However, there is a problem of compatibility with the cured product when a cross-linked charge transport layer contains a low molecular charge transport material. As a result, precipitation of a low-molecular charge transport material and white turbidity occur, and not only the image density is lowered but also the mechanical strength is lowered due to the increase of the exposed portion potential. Furthermore, since this photoconductor specifically reacts with the monomer in a state containing a polymer binder, the three-dimensional network structure does not proceed sufficiently, and the crosslink density becomes dilute, resulting in a dramatic wear resistance. Has not yet been able to demonstrate.

  As a wear resistance technique for the photosensitive layer related to these, a charge transport layer formed by using a coating solution comprising a monomer having a carbon-carbon double bond, a charge transport material having a carbon-carbon double bond, and a binder resin. It is known to provide (for example, refer patent document 43). This binder resin is considered to play a role of improving the adhesion between the charge generation layer and the curable charge transport layer, and further relaxing the internal stress of the film during thick film curing, and has a carbon-carbon double bond. These are roughly classified into those having reactivity with the charge transporting substance and those having no reactivity with the double bond. This photoconductor is remarkably compatible with wear resistance and good electrical properties, but when a non-reactive binder resin is used, the binder resin, the monomer, and the charge transport material are used. The compatibility with the cured product produced by this reaction is poor, and layer separation occurs in the cross-linked charge transport layer, which may cause scratches and adhesion of external additives and paper powder in the toner. In addition, as described above, the three-dimensional network structure does not proceed sufficiently, and the cross-linking density becomes dilute. In addition, what is specifically described as the monomer used in this photoreceptor is bifunctional, and in these respects, it has not yet been satisfactory in terms of wear resistance. Even when a reactive binder is used, the molecular weight of the cured product is increased, but the number of intermolecular crosslinks is small, and it is difficult to achieve a balance between the amount of the charge transporting substance and the crosslink density. Abrasion was not sufficient.

  A photosensitive layer containing a compound obtained by curing a hole transporting compound having two or more chain polymerizable functional groups in the same molecule is also known (see, for example, Patent Document 44). This photosensitive layer has high hardness because the crosslink density can be increased, but since the bulky hole transporting compound has two or more chain polymerizable functional groups, distortion occurs in the cured product and internal stress increases. In some cases, the crosslinked surface layer is liable to crack or peel off when used for a long period of time. Even in the conventional photoconductors having a cross-linked photosensitive layer in which a charge transporting structure is chemically bonded, it cannot be said that the present invention has sufficient comprehensive characteristics.

In this way, scumming is affected not only by the intermediate layer or subbing layer, but also by the charge generation layer and the charge transport layer or protective layer. It is difficult to achieve high durability of the photoreceptor. However, in the prior art, there are few examples in which all the layers constituting the photoconductor are suppressed from soiling, and when all these layers are improved simultaneously, the residual potential rises significantly or the charging property And the residual potential increases in humidity, the effects of filming and image blur increase, and image defects are more likely to occur due to scratches on the photoreceptor surface. As a result, high durability of the photoreceptor has not been realized.
JP-A-47-6341 JP-A-60-66258 JP 52-10138 A JP 58-105155 A JP 51-65942 A JP 52-82238 A JP-A-55-113045 JP 58-93062 A JP 58-58556 A Japanese Patent Laid-Open No. 60-111255 JP 59-17557 A JP 60-32054 A JP-A 64-68762 JP-A 64-68763 JP-A 64-73352 JP-A 64-73353 JP-A-1-118848 Japanese Patent Laid-Open No. 1-118849 JP 58-95351 A JP 59-93453 A Japanese Patent Laid-Open No. 4-170552 JP-A-6-208238 JP-A-6-222600 Japanese Patent Laid-Open No. 8-184979 JP-A-9-43886 Japanese Patent Laid-Open No. 9-190005 JP-A-9-288367 Japanese Patent Laid-Open No. 5-100461 Japanese Patent Laid-Open No. 5-210260 Japanese Patent Laid-Open No. 7-271072 Japanese Patent Laid-Open No. 5-80572 JP-A-6-19174 JP-A-9-265202 JP 2002-107984 A Japanese Patent No. 2718044 Japanese Patent No. 3086965 Japanese Patent No. 3226110 JP 2001-154379 A JP 56-48637 A JP-A 64-1728 JP-A-4-281461 Japanese Patent No. 3262488 Japanese Patent No. 3194392 JP 2000-66425 A Japanese Patent Laid-Open No. 3-109460 JP 2000-206723 A JP 2001-340001 A JP 2004-83859 A

Accordingly, an object of the present invention is to generate an abnormal image when repeatedly used at a high speed in an image forming apparatus that employs a system in which a toner image formed on a photoconductor is transferred to a transfer medium by a direct transfer system. And an image forming apparatus that outputs an image in a stable state.
Specifically, in an image forming apparatus that employs a method of transferring a toner image formed on a photosensitive member to a transfer target by a direct transfer method in order to form a high-quality image at high speed, In addition to controlling the scumming caused by the injection of electric charge and preventing the increase in scumming promoted by electrostatic fatigue due to long-term repeated use and the increase in electric field strength due to wear, the increase in residual potential and the decrease in charging In addition, it minimizes the occurrence of image defects such as filming, adhesion of foreign matter, and image flow due to improved wear resistance, thereby solving the biggest problems in negative / positive development systems such as background contamination and density reduction. An object of the present invention is to provide an image forming apparatus having dramatically high durability and high stability.
Another object of the present invention is to provide an image forming apparatus equipped with a process cartridge for an image forming apparatus that is highly durable, highly stable, and has good handling.

  In the high-speed image forming apparatus adopting the direct transfer method, the present inventors have made a number of studies in order to form an image with few abnormal images even during repeated use. 1. An electrophotographic photosensitive member in which at least a charge blocking layer, a moire preventing layer, a photosensitive layer (a charge generation layer and a charge transport layer) and a protective layer are sequentially laminated on the body, and the protective layer has at least a charge transporting structure. The present inventors have found that the above-mentioned problems can be solved by curing a radical polymerizable monomer having three or more functional groups and a radical polymerizable compound having a monofunctional charge transporting structure.

  It was understood that the problem of abnormal images (background stains) in the high-speed image formation described above was due to a charge leak phenomenon during charging of the photoreceptor. Further, when the direct transfer method is used, the electrostatic fatigue of the photosensitive member is promoted as described above, and this leakage phenomenon becomes more remarkable. In the present invention, it is presumed that the above problem can be solved by reducing the charge leakage phenomenon at the time of charging by using an intermediate layer composed of a laminated structure of a charge blocking layer and a moire preventing layer. .

  As described above, an effective means for controlling the process has been developed, but an effective photoconductor that takes advantage of the feature has not been developed. Therefore, a high electric field strength cannot be applied to improve the image quality. The current problem is that the electrostatic latent image that is faithful to the writing dots on the photoconductor and the toner development that is faithful to the electrostatic latent image remain, but the present invention solves this problem. ing.

That is, the said subject is solved by following this invention (1)-(33).
(1) In an image forming apparatus having at least an electrophotographic photosensitive member, a charging unit, and a transfer member that directly transfers a toner image formed on the electrophotographic photosensitive member to a transfer target, the electrophotographic photosensitive member Is an electrophotographic photosensitive member in which at least a charge blocking layer, a moire preventing layer, a photosensitive layer, and a protective layer are sequentially laminated on a conductive support, and the protective layer has at least a trifunctional or more functional group having no charge transporting structure. An image forming apparatus, which is formed by curing a radical polymerizable monomer and a radical polymerizable compound having a monofunctional charge transporting structure.

(2) The image forming apparatus according to item (1), wherein the photosensitive layer has a laminated structure in which a charge generation layer and a charge transport layer are sequentially laminated.
(3) The image according to (1) or (2), wherein the charge blocking layer is made of an insulating material, and the film thickness is less than 2.0 μm and 0.3 μm or more. Forming equipment.
(4) The image forming apparatus according to item (3), wherein the insulating material is polyamide.
(5) The image forming apparatus according to (4), wherein the polyamide is N-methoxymethylated nylon.

(6) The items (1) to (5), wherein the moire preventing layer contains an inorganic pigment and a binder resin, and the volume ratio thereof is in a range of 1/1 to 3/1. The image forming apparatus according to any one of the above.
(7) The image forming apparatus according to item (6), wherein the binder resin is a thermosetting resin.
(8) The image forming apparatus according to (7), wherein the thermosetting resin is an alkyd / melamine resin mixture.
(9) The image forming apparatus as described in (8) above, wherein the mixing ratio of the alkyd resin and the melamine resin is in the range of 5/5 to 8/2 (weight ratio).

(10) The image forming apparatus according to any one of (6) to (9), wherein the inorganic pigment is titanium oxide.
(11) The titanium oxide is two types of titanium oxides having different average particle diameters, the average particle diameter of the titanium oxide (T1) having the larger average particle diameter is D1, and the average particle of the other titanium oxide (T2) is The image forming apparatus according to item (10), wherein the relationship of 0.2 <(D2 / D1) ≦ 0.5 is satisfied when the diameter is D2.
(12) The image forming apparatus according to (11), wherein the titanium oxide (T2) has an average particle diameter (D2) of 0.05 μm <D2 <0.20 μm.
(13) The said (11) term | claim characterized by the mixing ratio (weight ratio) of the two types of titanium oxides having different average particle diameters being 0.2 ≦ T2 / (T1 + T2) ≦ 0.8 The image forming apparatus according to item (12).

(14) Any one of (1) to (13) above, wherein the photosensitive layer or the charge transport layer contains a polycarbonate having at least a triarylamine structure in the main chain and / or side chain. The image forming apparatus described in 1.
(15) The image forming apparatus according to any one of (1) to (14), wherein the protective layer is insoluble in an organic solvent.
(16) The functional group of the tri- or higher functional radical polymerizable monomer having no charge transporting structure used for the protective layer is an acryloyloxy group and / or a methacryloyloxy group. Item 15. The image forming apparatus according to any one of Items (15) to (15).
(17) The ratio of the molecular weight to the number of functional groups (molecular weight / number of functional groups) in the trifunctional or higher functional radical polymerizable monomer having no charge transporting structure used in the protective layer is 250 or less. The image forming apparatus according to any one of (1) to (16).

(18) Item (1) to Item (1), wherein the functional group of the radically polymerizable compound having a monofunctional charge transporting structure used in the protective layer is an acryloyloxy group or a methacryloyloxy group. The image forming apparatus according to any one of items 17).
(19) The charge transporting structure of the radical polymerizable compound having a monofunctional charge transporting structure used for the protective layer is a triarylamine structure, wherein (1) to (18) The image forming apparatus according to any one of the above items.

｛式中、Ｒ₁は水素原子、ハロゲン原子、置換基を有してもよいアルキル基、置換基を有してもよいアラルキル基、置換基を有してもよいアリール基、シアノ基、ニトロ基、アルコキシ基、−ＣＯＯＲ₇（Ｒ₇は水素原子、置換基を有してもよいアルキル基、置換基を有してもよいアラルキル基又は置換基を有してもよいアリール基）、ハロゲン化カルボニル基若しくはＣＯＮＲ₈Ｒ₉（Ｒ₈及びＲ₉は水素原子、ハロゲン原子、置換基を有してもよいアルキル基、置換基を有してもよいアラルキル基又は置換基を有してもよいアリール基を示し、互いに同一であっても異なっていてもよい）を表わし、Ａｒ₁、Ａｒ₂は置換もしくは無置換のアリーレン基を表わし、同一であっても異なってもよい。Ａｒ₃、Ａｒ₄は置換もしくは無置換のアリール基を表わし、同一であっても異なってもよい。Ｘは単結合、置換もしくは無置換のアルキレン基、置換もしくは無置換のシクロアルキレン基、置換もしくは無置換のアルキレンエーテル基、酸素原子、硫黄原子、ビニレン基を表わす。Ｚは置換もしくは無置換のアルキレン基、置換もしくは無置換のアルキレンエーテル２価基、アルキレンオキシカルボニル２価基を表わす。ｍ、ｎは０〜３の整数を表わす。｝ (20) The first (1), wherein the radical polymerizable compound having a monofunctional charge transporting structure used in the protective layer is at least one of the following general formula (1) or (2): Item 20. The image forming apparatus according to any one of Items (19) to (19).

{In the formula, R ₁ represents a hydrogen atom, a halogen atom, an alkyl group which may have a substituent, an aralkyl group which may have a substituent, an aryl group which may have a substituent, a cyano group, a nitro group, Group, alkoxy group, —COOR ₇ (R ₇ is a hydrogen atom, an alkyl group which may have a substituent, an aralkyl group which may have a substituent or an aryl group which may have a substituent), halogen Carbonyl group or CONR ₈ R ₉ (R ₈ and R ₉ may have a hydrogen atom, a halogen atom, an alkyl group which may have a substituent, an aralkyl group which may have a substituent, or a substituent. Represents a good aryl group, which may be the same or different, and Ar ₁ and Ar ₂ represent a substituted or unsubstituted arylene group, which may be the same or different. Ar ₃ and Ar ₄ represent a substituted or unsubstituted aryl group, and may be the same or different. X represents a single bond, a substituted or unsubstituted alkylene group, a substituted or unsubstituted cycloalkylene group, a substituted or unsubstituted alkylene ether group, an oxygen atom, a sulfur atom, or a vinylene group. Z represents a substituted or unsubstituted alkylene group, a substituted or unsubstituted alkylene ether divalent group, or an alkyleneoxycarbonyl divalent group. m and n represent an integer of 0 to 3. }

（式中、ｏ、ｐ、ｑはそれぞれ０又は１の整数、Ｒａは水素原子、メチル基を表わし、Ｒｂ、Ｒｃは水素原子以外の置換基で炭素数１〜６のアルキル基を表わし、複数の場合は異なっても良い。ｓ、ｔは０〜３の整数を表わす。Ｚａは単結合、メチレン基、エチレン基、

を表わす。） (21) Item (1) to Item (1), wherein the radical polymerizable compound having a monofunctional charge transporting structure used in the protective layer is at least one of the following general formula (3). The image forming apparatus according to any one of 20).

(Wherein, o, p and q are each an integer of 0 or 1, Ra represents a hydrogen atom or a methyl group, Rb and Rc represent a substituent other than a hydrogen atom and an alkyl group having 1 to 6 carbon atoms, And s and t each represents an integer of 0 to 3. Za is a single bond, a methylene group, an ethylene group,

Represents. )

(22) The first (1) characterized in that the proportion of the trifunctional or higher functional radical polymerizable monomer having no charge transporting structure used in the protective layer is 30 to 70% by weight based on the total amount of the protective layer. ) To (21).
(23) The said (1) term | claim characterized by the component ratio of the radically polymerizable compound which has the monofunctional charge transporting structure used for the said protective layer being 30 to 70 weight% with respect to the protective layer whole quantity. The image forming apparatus according to any one of Items (22) to (22).
(24) The image forming apparatus according to any one of (1) to (23), wherein the curing unit of the protective layer is a heating or light energy irradiation unit.

(25) The image forming apparatus according to any one of (1) to (24), wherein the transfer current is controlled by constant current control in the image forming apparatus.
(26) The image forming apparatus includes a feedback mechanism that measures a current flowing through the transfer member in the transfer member, and a transfer that flows to the photoconductor by a difference from an output current from a high-voltage power source that applies a current to the transfer member. The image forming apparatus according to any one of (1) to (25), wherein an electric current is obtained and controlled.

(27) In the image forming apparatus, the photosensitive member surface potential after transfer in the non-writing portion is 100 V or less as an absolute value of the polarity charged by the charging unit. The image forming apparatus according to any one of (26).
(28) In the image forming apparatus, the photosensitive member surface potential after transfer in the non-writing portion is opposite to the polarity charged by the charging means. (1) to (26) The image forming apparatus according to any one of the items.
(29) In the image forming apparatus, the photosensitive member surface potential after transfer in the non-writing portion is 100 V or less as an absolute value of the reverse polarity of the polarity charged by the charging unit. The image forming apparatus according to the item.

(30) The image forming apparatus according to any one of (1) to (29), wherein the image forming apparatus does not use a light neutralization mechanism.
(31) The image forming apparatus according to any one of (1) to (30), wherein an AC superimposed voltage is applied to a charging unit of the electrophotographic apparatus.
(32) Any one of (1) to (31) above, wherein a plurality of image forming elements comprising at least charging means, exposure means, developing means, and electrophotographic photosensitive member are arranged. Image forming apparatus.
(33) An apparatus main body and a detachable cartridge are mounted in which an electrophotographic photosensitive member and at least one means selected from charging means, exposure means, developing means, and cleaning means are integrated. The image forming apparatus according to any one of (1) to (32).

According to the present invention, in an image forming apparatus that employs a system in which a toner image formed on a photoconductor is transferred to a transfer medium by a direct transfer system, there is no occurrence of an abnormal image when it is repeatedly used at high speed, and is stable. An image forming apparatus that outputs an image with high resolution is provided.
Specifically, in an image forming apparatus using a direct transfer system in order to form a high-quality image, an intermediate layer in which a charge blocking layer and a moire prevention layer are sequentially laminated on at least a conductive support as the photoreceptor. It is formed by curing a radically polymerizable monomer having at least three functional groups having no charge transport structure and a radical polymerizable compound having a monofunctional charge transport structure on the surface of the photoreceptor (photosensitive layer). By using a photoreceptor having a protective layer, an image forming apparatus capable of outputting images with high durability and high speed is provided.

  Further, it has at least an intermediate layer in which a charge blocking layer and a moire prevention layer are sequentially laminated on a conductive support, and has at least a trifunctional or higher functional radical polymerization property having no charge transporting structure on the surface of the photoreceptor (photosensitive layer). By having a protective layer formed by curing a monomer and a radically polymerizable compound having a monofunctional charge transporting structure, it becomes possible to suppress the occurrence of background contamination even in long-term repeated use. There is provided an image forming apparatus that has very little potential variation with time, can suppress image defects such as image flow and filming, and can stably output a high-quality image over a long period of time.

Further, by using the protective layer of the present invention, the smoothness of the surface is maintained even after repeated use, and good cleaning characteristics are maintained even when a small particle size or spherical toner is used. As a result, it is possible to provide a stable image forming apparatus that prevents abnormal images caused by defective cleaning.
Further, since the high durability and high stability of the image forming apparatus are realized in this way, it is possible to reduce the size and speed of the image forming apparatus. In particular, the tandem type image forming apparatus and the high speed image forming apparatus can be used. It can be used effectively.

First, the image forming apparatus of the present invention will be described in detail with reference to the drawings.
FIG. 7 is a schematic diagram for explaining the image forming apparatus of the present invention, and a modification as shown later also belongs to the category of the present invention.
In FIG. 7, the photoreceptor (1) is provided with at least a charge blocking layer, a moire preventing layer, a photosensitive layer, and a protective layer on a conductive support, and the protective layer does not have at least a charge transporting structure. It is formed by curing a radically polymerizable monomer having a functionality or higher and a radically polymerizable compound having a monofunctional charge transporting structure. The photoconductor (1) has a drum shape, but may be a sheet or an endless belt.
As the transfer means of the apparatus shown in FIG. 7, a direct transfer method is used in which the toner image formed on the surface of the photoreceptor is directly transferred to the transfer target.

  Any known member can be used as the charging member (3) as long as it can sufficiently charge the photosensitive member. Among them, a scorotron charging member, a contact charging member (roller shape), or a charging member in which the surface of the photosensitive member and the charging member surface are arranged close to 100 μm or less is preferably used. When the dot reproducibility is prioritized for the purpose of high-definition image formation, an electric field strength of 30 V / μm or more is applied to the photoreceptor by this charging member. The higher the electric field strength applied to the photoconductor, the better the dot reproducibility. However, there is a possibility of causing problems of dielectric breakdown of the photoconductor and carrier adhesion at the time of development, and the upper limit is about 60 V / μm or less. Preferably, it is 50 V / μm or less.

  The image exposure unit (5) uses a light source capable of ensuring high brightness and capable of writing at a resolution of 600 dpi or more, such as a light emitting diode (LED), a semiconductor laser (LD), and electroluminescence (EL). . Depending on the resolution of the light source (writing light), the resolution of the formed electrostatic latent image, and thus the toner image, is determined. The higher the resolution, the clearer the image. However, if writing is performed with a higher resolution, the time required for writing becomes longer. Therefore, if there is one writing light source, writing is limited by the drum linear speed (process speed). Therefore, when there is one writing light source, a resolution of about 1200 dpi is the upper limit. When there are a plurality of writing light sources, each of them only needs to bear a writing area, and “1200 dpi × number of writing light sources” is practically the upper limit. The writing light source here refers to one LD element or one LED element. For example, LEDs arranged in an array are handled as a plurality of light sources.

  The developing unit (6) can handle both normal development and reversal development depending on the charging polarity of the toner used. When a toner having a polarity opposite to the charged polarity of the photoreceptor is used, normal development is used. When a toner having the same polarity is used, the electrostatic latent image is developed by reversal development. Depending on the light source used in the previous image exposure unit, in the case of a digital light source used in recent years, there is generally a reversal development method in which toner development is performed on the writing portion in response to a low image area ratio. This is advantageous in view of the lifetime of the light source. There are two methods, a one-component method in which development is performed with toner alone and a two-component method in which a two-component developer composed of toner and carrier is used.

As the transfer member, a member of a type in which a toner image formed on a photoconductor is directly transferred to a transfer target such as paper on which output is used.
Although FIG. 7 shows a transfer charger (10) as a transfer member, a transfer belt and a transfer roller can also be used. Among them, it is desirable to use a contact type such as a transfer belt or a transfer roller that generates less ozone. Any known transfer member may be used as long as it can satisfy the configuration of the present invention.

  As a voltage / current application method at the time of transfer, either a constant voltage method or a constant current method can be used, but the transfer charge amount can be kept constant, and a constant voltage with excellent stability can be used. The current method is more desirable. In particular, by subtracting the current that flows from the power supply member (high-voltage power supply) that supplies electric charge to the transfer member and does not flow into the photosensitive member, the current to the photosensitive member is subtracted. A method of controlling the value is preferred. Specifically, in order to obtain the current flowing through the roller holding the transfer belt, the related member such as the roller is not dropped directly to the ground, but the current flowing through the related member is returned to the high voltage power source. It is desirable to obtain a difference from the output of the power supply and perform constant current control using a high-voltage power supply having a feedback function so that the difference becomes a constant value. An example of a circuit configuration diagram that can take such a form is shown in FIG.

  The transfer current is a current based on the amount of charge required to peel off the toner electrostatically attached to the photosensitive member and transfer it to a transfer target (transfer paper or intermediate transfer member). In order to avoid transfer defects such as transfer residue, it is only necessary to increase the transfer current. However, when negative / positive development is used, charging with a polarity opposite to the charging polarity of the photoconductor is applied. As a result, the electrostatic fatigue of the photoconductor becomes remarkable. For this reason, in the electrophotographic apparatus so far, the deterioration of the electrostatic fatigue characteristics due to the reverse charging applied to the photoreceptor is rate-limiting, and it is difficult to increase the transfer current. The present inventors have found that this problem can be solved by using a photoreceptor using a titanyl phthalocyanine crystal having a specific crystal type.

  The larger the transfer current, the more advantageous it is because the charge amount exceeding the electrostatic adhesion force between the photoconductor and the toner can be given. As a result, the developed toner image is scattered. Therefore, the upper limit value is a range that does not cause this discharge phenomenon. This threshold value varies depending on the gap (distance) between the transfer member and the photoconductor, the material constituting the both, and the like, but the discharge phenomenon can be avoided by using it at about 200 μA or less. Therefore, the upper limit value of the transfer current is about 200 μA.

  At this time, the surface potential of the photoreceptor after transfer has a great influence on the electrostatic fatigue of the photoreceptor in repeated use. That is, the electrostatic fatigue of the photoreceptor is greatly influenced by the amount of charge passing through the photoreceptor. This passing charge amount corresponds to the amount of charge flowing in the film thickness direction of the photoreceptor. As an operation in the image forming apparatus of the photoconductor, the charging unit (main charger) is charged to a desired charging potential (in most cases, negatively charged), and optical writing is performed based on an input signal corresponding to the document. At this time, photocarriers are generated in the portion where writing is performed, and the surface charge is neutralized (potential decay). At this time, the amount of charge depending on the amount of generated photocarriers flows in the direction of the photoreceptor film thickness.

  On the other hand, the area where the optical writing is not performed (non-writing portion) proceeds to the charge removal process through the development process and the transfer process (a cleaning process is performed before that if necessary). Here, when the surface potential of the photoconductor is close to the potential applied by the main charger (excluding dark decay), the photoconductor film thickness is approximately the same amount as the area where optical writing has been performed. Will flow in the direction. In general, since the current document has a low writing rate, this method means that the current passing through the photoconductor in repeated use is mostly current flowing in the static elimination process (the writing rate is 10%). Then, the current flowing in the static elimination process occupies 90% of the total).

This passing charge greatly affects the electrostatic characteristics of the photoconductor, for example, causing deterioration of the material constituting the photoconductor. As a result, the residual potential of the photosensitive member is raised, depending on the amount of passing charge. When the residual potential of the photosensitive member is increased, the image density is lowered in the negative / positive development used in the present invention, which is a serious problem. Therefore, there is a problem of how to reduce the passing charge amount of the photosensitive member in order to extend the life (high durability) of the photosensitive member in the image forming apparatus.
On the other hand, there is a way of thinking that the photostatic discharge is not performed, but if the main charger is not large in charging ability, the charging cannot be stabilized and a problem such as an afterimage may occur.

The passing charge of the photosensitive member is generated by the movement of the generated optical carrier by light irradiation by the potential charged on the surface of the photosensitive member (the electric field generated thereby). Therefore, if the photoreceptor surface potential can be attenuated by means other than light, the amount of passing charge per rotation of the photoreceptor (one cycle of image formation) can be reduced.
For this purpose, it is effective to adjust the charge passing through the photosensitive member by adjusting the transfer bias in the transfer process. That is, the non-writing portion that is charged by the main charger and does not perform writing enters the transfer process in a state close to the charged potential except for the dark attenuation amount. At this time, by reducing the absolute value of the polarity charged by the main charger to 100 V or less, even when entering the subsequent static elimination process, almost no photocarrier is generated and no passing charge is generated. This value is preferably closer to 0V.

  Furthermore, by adjusting the transfer bias, by applying a transfer bias so that the surface potential of the photosensitive member is charged to a polarity opposite to the charging polarity applied by the main charging, it is more preferable because no optical carrier is generated. . However, under transfer conditions that charge to a reverse polarity, there may be cases where a large amount of transfer dust occurs or the main charge of the next image forming process (cycle) cannot catch up. In that case, since a problem such as an afterimage may occur, the absolute value of the reverse polarity is preferably 100 V or less.

  Use light sources such as fluorescent lamps, tungsten lamps, halogen lamps, mercury lamps, sodium lamps, light emitting diodes (LEDs), semiconductor lasers (LDs), and electroluminescence (ELs) as light sources such as static elimination lamps (2). Can do. 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.

Such a light source or the like irradiates the photosensitive member with light by providing a transfer process, a static elimination process, a cleaning process, or a pre-exposure process using light irradiation in addition to the process shown in FIG.
This neutralization mechanism can be omitted when the AC component is used in a superposed manner in the previous charging method, or when the residual potential of the photoreceptor is small. Further, instead of optical static elimination, an electrostatic static elimination mechanism (for example, a static elimination brush with a reverse bias applied or grounded) can be used. As described above, a document with a small writing rate has a large effect of light neutralization, and it is preferable not to use light neutralization as long as there is no effect of afterimages in the next image forming cycle.
In the figure, 7 is a pre-transfer charger, 8 is a registration roller, 11 is a separation charger, 12 is a separation claw, and 13 is a charger before cleaning.

  In addition, the toner developed on the photoreceptor (1) by the developing unit (6) is transferred to the transfer paper (9). 14) and the cleaning 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.

FIG. 9 is a schematic diagram for explaining the tandem-type full-color image forming apparatus of the present invention, and the following modifications also belong to the category of the present invention.
In FIG. 9, reference numerals (16Y), (16M), (16C), and (16K) are drum-shaped photoreceptors, and the photoreceptors are at least a charge blocking layer, a moire preventing layer, a photosensitive layer, And a protective layer is formed, and the protective layer is formed by curing at least a trifunctional or higher functional radical polymerizable monomer having no charge transporting structure and a radical polymerizable compound having a monofunctional charge transporting structure. Being done.

  The photosensitive members (16Y), (16M), (16C), and (16K) rotate in the direction of the arrow in the figure, and charging members (17Y), (17M), (17C), (17K) at least in the order of rotation therearound. ), Developing members (19Y), (19M), (19C), (19K), cleaning members (20Y), (20M), (20C), (20K), neutralizing members (27Y), ( 27M), (27C), and (27K) are arranged. The charging members (17Y), (17M), (17C), and (17K) are charging members that constitute a charging device for uniformly charging the surface of the photoreceptor. From the photosensitive member surface side between the charging members (17Y), (17M), (17C), (17K) and the developing members (19Y), (19M), (19C), (19K), an exposure member (not shown) Laser beams (18Y), (18M), (18C), and (18K) are irradiated so that an electrostatic latent image is formed on the photoconductors (16Y), (16M), (16C), and (16K). It has become. Then, the four image forming elements (25Y), (25M), (25C), and (25K) centering on such photoconductors (16Y), (16M), (16C), and (16K) serve as transfer materials. They are juxtaposed along the transfer conveyance belt (22) which is a conveyance means.

  The transfer conveyance belt (22) is a means for directly transferring the toner image on the photosensitive member to the transfer target (26). Each image forming unit (25Y), (25M), (25C), (25K) Between the developing members (19Y), (19M), (19C), (19K) and the cleaning members (20Y), (20M), (20C), (20K). 16C) and (16K), and transfer brushes (21Y), (21M), (21C) for applying a transfer bias to the back surface (back surface) of the transfer conveyance belt (22) which is in contact with the back side of the photoconductor. , (21K) are arranged. Each of the image forming elements (25Y), (25M), (25C), and (25K) is different in the color of the toner inside the developing device, and the others are the same in configuration.

  In the full-color image forming apparatus having the configuration shown in FIG. 9, the image forming operation is performed as follows. First, in each of the image forming elements (25Y), (25M), (25C), and (25K), an electrostatic latent image is formed on the photoconductors (16Y), (16M), (16C), and (16K). It has become. Then, the photosensitive members (16Y), (16M), (16C), and (16K) rotate, and the photosensitive member is charged by the charging members (17Y), (17M), (17C), and (17K). The At this time, in order to form a high-definition latent image, charging is performed so that the electric field strength of the photosensitive member is 30 V / μm or more (60 V μm or less, preferably 50 V / μm or less).

Next, writing is performed at a resolution of 600 dpi or more (preferably 1200 dpi or more) by laser light (18Y), (18M), (18C), and (18K) at an exposure unit (not shown) arranged outside the photoreceptor. Then, an electrostatic latent image corresponding to each color image to be created is formed. Also in this case, 1200 dpi writing is generally the upper limit for one writing light source.
Next, the developing member (19Y), (19M), (19C), (19K) develops the latent image to form a toner image. Development members (19Y), (19M), (19C), and (19K) are development members that perform development with toners of Y (yellow), M (magenta), C (cyan), and K (black), respectively. The toner images of the respective colors formed on the two photoconductors (16Y), (16M), (16C), and (16K) are superimposed on the transfer target. The transfer body (26) is fed out of the tray by a paper feed roller (not shown), temporarily stopped by a pair of registration rollers (23), and transferred to a transfer and transport belt (in accordance with the timing of image formation on the photoreceptor). 22). The transfer target (26) held on the transfer / conveying belt (22) is transported and is in contact with the respective photosensitive members (16Y), (16M), (16C), and (16K) (transfer section). Each color toner image is transferred.

The toner image on the photoconductor includes transfer bias applied to the transfer brushes (21Y), (21M), (21C), and (21K) and the photoconductors (16Y), (16M), (16C), and (16K). Is directly transferred onto the transfer medium (26) by an electric field formed by the potential difference between the two. Then, the transfer target (26) on which the four color toner images are passed through the four transfer portions is conveyed to the fixing device (24), where the toner is fixed, and is discharged to a discharge portion (not shown). .
Further, residual toner remaining on each of the photoconductors (16Y), (16M), (16C), and (16K) without being transferred by the transfer unit is removed from the cleaning devices (20Y), (20M), (20C), ( 20K).
Subsequently, excess residual charges on the photosensitive member are removed by the charge eliminating members (27Y), (27M), (27C), and (27K). Thereafter, the charging member is uniformly charged again, and the next image formation is performed.

In the example of FIG. 9, the image forming elements are arranged in the order of Y (yellow), M (magenta), C (cyan), and K (black) from the upstream side to the downstream side in the transfer paper conveyance direction. However, the order is not limited to this order, and the color order is arbitrarily set. Further, when creating a black-only document, it is particularly effective to use the present invention to provide a mechanism for stopping image forming elements other than black ((25Y), (25M), (25C)). .
Further, as described above, the surface potential of the photosensitive member after transfer is controlled to 100 V or less, preferably reverse polarity, more preferably 100 V or less, on the main charging polarity side, thereby remaining in the repeated use of the photosensitive member. An increase in potential can be reduced, which is effective.

The image forming means as described above may be fixedly incorporated in a copying apparatus, facsimile, or printer, but each electrophotographic element may be incorporated in the apparatus in the form of a process cartridge. A process cartridge is a single device (part) that contains a photoconductor and further includes a charging unit, an exposure unit, a developing unit, a transfer unit, a cleaning unit, a neutralizing unit, and the like.
There are many shapes and the like of the process cartridge, but a general example is shown in FIG. The photoconductor (101) is a trifunctional or higher functional radical in which at least a charge blocking layer, a moire preventing layer, a photosensitive layer, and a protective layer are provided on a conductive support, and the protective layer does not have at least a charge transporting structure. It is formed by curing a polymerizable monomer and a radical polymerizable compound having a monofunctional charge transporting structure.

In this case as well, a system is used in which the toner image formed on the photoconductor is directly transferred to the transfer medium by the transfer means. As the charging member (102), a known charging member is used as described above. When a high-definition image is formed, the charging member is 30 V / μm or more (60 V / μm or less, preferably 50 V / μm or less). The following electric field strength is applied.
As described above, a light source capable of writing at a resolution of 600 dpi or higher (preferably 1200 dpi or higher) is used for the image exposure unit (103). In FIG. 10, 104 is a developing unit, 105 is a transfer target, Reference numeral 106 denotes a transfer unit, 107 denotes a cleaning unit, and 108 denotes a charge removal unit.

Hereinafter, the electrophotographic photosensitive member used in the image forming apparatus of the present invention will be described in detail.
The electrophotographic photosensitive member according to the present invention is an electrophotographic photosensitive member in which at least a charge blocking layer, a moire preventing layer, a photosensitive layer, and a protective layer are provided on a conductive support, and the protective layer has at least a charge. It is formed by curing a tri- or higher functional radical polymerizable monomer having no transporting structure and a radical polymerizable compound having a monofunctional charge transporting structure.

  The structure of the intermediate layer in which the charge blocking layer and the moire preventing layer are laminated in this order between the conductive support and the photosensitive layer is a technique described in Patent Document 28 as described above, but achieves high sensitivity. In the combination with the photosensitive layer that can be produced, there is a case where the influence of the generation of the heat carrier in the photosensitive layer is large, and the soiling cannot always be completely prevented. This tendency becomes a significant problem when, for example, a charge generating material having absorption at a long wavelength typified by a titanyl phthalocyanine crystal is used.

  Moreover, the technique which provides a protective layer in the upper layer of a photosensitive layer is described in patent documents 40-42. By these techniques, the amount of wear in the repeated use of the photoreceptor can be reduced, and the increase in the electric field strength in the use of the photoreceptor can be reduced. Thus, although the background stain can be reduced to some extent, the occurrence of the background stain due to a decrease in charging property due to electrostatic fatigue of the photosensitive layer based on repeated use over a long period cannot be suppressed. Furthermore, when the wear resistance is improved by providing a protective layer, the above-described problems such as an increase in residual potential and poor cleaning may be caused, which is not always satisfactory.

As described above, although a method of suppressing soiling in the intermediate layer or the protective layer is disclosed, there are a plurality of soiling factors, and if they are not controlled simultaneously, they are used repeatedly for a long time. It is impossible to endure. It is a very small dirt factor, and even if it does not become a problem in the initial state, the dirt factor grows as the photoreceptor is fatigued or the deterioration of constituent materials progresses due to repeated use. Because. Therefore, it is necessary to eliminate the cause of background contamination as much as possible and to improve the stability against fatigue of the photoreceptor in repeated use. However, there has been no disclosure of a method for solving these problems at the same time and enabling dramatic improvement in durability.
Therefore, at least a trifunctional or higher functional radical polymer having an intermediate layer in which a charge blocking layer and a moire preventing layer are sequentially laminated on a conductive support and having no charge transporting structure on the surface of the photoreceptor (photosensitive layer). By using an electrophotographic photosensitive member having a protective layer formed by curing a monomer and a radically polymerizable compound having a monofunctional charge transporting structure, it is possible to suppress the occurrence of scumming even in long-term repeated use. It has also been found that fluctuations in the exposure portion potential with time are very small, occurrence of image defects such as image flow and filming can be suppressed, and high-quality images can be output stably over a long period of time.

Next, the electrophotographic photosensitive member used in the present invention will be described in detail with reference to the drawings.
FIG. 11 is a cross-sectional view showing a structural example of the electrophotographic photosensitive member used in the present invention. On the conductive support (201), a charge blocking layer (205), a moire preventing layer (206), a photosensitive layer ( 204), and a protective layer (209) formed by curing at least a trifunctional or higher functional radical polymerizable monomer having no charge transport structure and a radical polymerizable compound having a monofunctional charge transport structure. Are sequentially stacked.
FIG. 12 is a cross-sectional view showing another structural example of the electrophotographic photosensitive member used in the present invention. On the conductive support (201), the charge blocking layer (205), the moire preventing layer (206), the charge A charge generation layer (207) mainly composed of a generating material, a charge transport layer (208) mainly composed of a charge transport material, and at least a trifunctional or higher functional radical polymerizable monomer having no charge transport structure and monofunctional The protective layer (209) formed by hardening | curing the radically polymerizable compound which has the following charge transportable structure has taken the structure laminated | stacked in order.

Examples of the conductive support include those having a volume resistance of 10 ¹⁰ Ω · cm or less, such as metals such as aluminum, nickel, chromium, nichrome, copper, gold, silver, and platinum, tin oxide, and indium oxide. Metal oxide coated with film or cylindrical plastic or paper by vapor deposition or sputtering, or a plate made of aluminum, aluminum alloy, nickel, stainless steel, etc. After the conversion, a tube subjected to surface treatment such as cutting, superfinishing or polishing can be used. Endless nickel belts and endless stainless steel belts can also be used as the conductive support.

  In addition, the conductive support dispersed in a suitable binder resin on the support can be used as the conductive 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. It is done. The binder resin used at the same time is polystyrene, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer, polyester, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer. , Polyvinyl acetate, polyvinylidene chloride, polyarylate resin, phenoxy resin, polycarbonate, cellulose acetate resin, ethyl cellulose resin, polyvinyl butyral, polyvinyl formal, polyvinyl toluene, poly-N-vinyl carbazole, acrylic resin, silicone resin, epoxy resin, Examples thereof include thermoplastic, thermosetting resins, and photocurable resins such as melamine resin, urethane resin, phenol resin, and alkyd resin. Such a conductive layer can be provided by dispersing and coating these conductive powder and binder resin in a suitable solvent such as tetrahydrofuran, dichloromethane, methyl ethyl ketone, and toluene.

  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 the conductive support of the present invention.

  Next, the charge blocking layer and the moire preventing layer will be described. The role of such an intermediate layer is to suppress injection of reverse polarity charges induced on the conductive support during charging of the photoreceptor, to prevent moire, to conceal defects in the tube, It has many roles such as maintaining adhesiveness. When the intermediate layer is a single layer as usual, if the charge injection from the conductive support is suppressed, the residual potential tends to increase, and conversely, if the residual potential is reduced, the soiling becomes worse. As a result of functional separation of such a trade-off relationship by forming a plurality of intermediate layers, the scumming suppression effect can be significantly improved without significantly affecting the residual potential. In the present invention, the effect is exhibited by laminating a plurality of intermediate layers. In particular, an intermediate layer containing no inorganic pigment (charge blocking layer) and an intermediate layer containing an inorganic pigment (moire prevention layer) ) In this order, at least two layers are laminated, so that there is little effect on the residual potential, and it is possible to greatly enhance the effect of suppressing scumming. It is possible to obtain a very large effect on the conversion.

First, the charge blocking layer whose main purpose is to suppress charge injection from the conductive support will be described.
The charge blocking layer is a layer that has the function of preventing the reverse polarity charge induced on the electrode (conductive support) during charging of the photoconductor from being injected into the photoconductive layer from the support, and mainly suppresses soiling. It is a layer intended to be made. In the case of negative charging, it has a function of preventing hole injection, and in the case of positive charging, it has a function of preventing electron injection. Moreover, it also has the effect of improving the concealment property against defects in the raw tube, and enhances the effect of suppressing soiling. Therefore, since it is required to suppress the movement of electric charges in order to achieve these objects, it is preferable that the resin is composed of only a highly insulating resin without containing an inorganic pigment.

  The charge blocking layer is formed of an anodized film typified by an aluminum oxide layer, an inorganic insulating layer typified by SiO, and a glassy network of metal oxide as described in JP-A-3-191361. A layer composed of polyphosphazene as described in JP-A-3-141363, a layer composed of an aminosilane reaction product as described in JP-A-3-101737, and other insulating layers. Examples thereof include a layer made of a curable binder resin and a layer made of a curable binder resin. Among them, a layer composed of an insulating binder resin or a curable binder resin that can be formed by a wet coating method can be used favorably. Since the charge blocking layer is formed by laminating a moire preventing layer and a photosensitive layer on the charge blocking layer, when these are provided by a wet coating method, the charge blocking layer must be composed of a material or a structure that does not attack the coating film by these coating solvents. Is essential.

Examples of binder resins that can be used include thermoplastic resins such as polyamide, polyester, vinyl chloride-vinyl acetate copolymer, and thermosetting resins such as active hydrogen (—OH group, —NH ₂ group, —NH group, etc.). A thermosetting resin obtained by thermally polymerizing a compound containing a plurality of (hydrogen) and a compound containing a plurality of isocyanate groups and / or a compound containing a plurality of epoxy groups can also be used. In this case, examples of the compound containing a plurality of active hydrogens include acrylic resins containing active hydrogen such as polyvinyl butyral, phenoxy resin, phenol resin, polyamide, polyester, polyethylene glycol, polypropylene glycol, polybutylene glycol, and hydroxyethyl methacrylate groups. System resin and the like. Examples of the compound containing a plurality of isocyanate groups include tolylene diisocyanate, hexamethylene diisocyanate, diphenylmethane diisocyanate, and prepolymers thereof. Examples of the compound having a plurality of epoxy groups include bisphenol A type epoxy resin. can give.

  In addition, a thermosetting resin obtained by thermally polymerizing an oil-free alkyd resin and an amino resin such as a butylated melamine resin, a polyurethane having an unsaturated bond, a resin having an unsaturated bond such as an unsaturated polyester, and thioxanthone A photocurable resin such as a combination with a photopolymerization initiator such as a compound based on methylbenzyl formate can also be used as the binder resin. Such alcohol-soluble resins and thermosetting resins have high insulation properties, and the liquid applied to the upper layer contains a lot of ketone-based solvents, so that the film elutes during coating. In addition, since a uniform film is maintained, it is excellent in the stability and uniformity of the antifouling effect.

  In the present invention, among these resins, polyamide is preferable, and N-methoxymethylated nylon is most preferable among them. The polyamide resin has a high effect of suppressing charge injection and has little influence on the residual potential. These polyamide resins are alcohol-soluble resins, are insoluble in other solvents, can form a uniform thin film even in dip coating, and have excellent coating properties. . In particular, this intermediate layer needs to be a thin film in order to minimize the effect of the increase in residual potential, and the uniformity of the film thickness is required. Therefore, the coatability has an important meaning in image quality stability. ing.

  In general, alcohol-soluble resins are highly dependent on humidity, which increases resistance in low-humidity environments and increases residual potential.In high-humidity environments, resistance decreases, leading to a decrease in charge and large environmental dependency. It was an issue. However, among polyamide resins, N-methoxymethylated nylon exhibits high insulating properties, is very excellent in blocking the charge injected from the conductive support, has little effect on the residual potential, and is environmentally friendly. Since the dependence is greatly reduced and stable image quality can always be maintained even if the use environment of the image forming apparatus changes, it is most suitably used when a moire prevention layer is laminated thereon. In addition, when N-methoxymethylated nylon is used, the film thickness dependence of the residual potential is small, so that it is possible to reduce the influence on the residual potential and obtain a high scumming suppression effect.

  The substitution rate of the methoxymethyl group in N-methoxymethylated nylon is not particularly limited, but is preferably 15 mol% or more. The above effect by using N-methoxymethylated nylon is affected by the degree of methoxymethylation. When the substitution rate of the methoxymethyl group is lower than this, the humidity dependency increases or the alcohol solution is used. In some cases, the aging stability of the coating solution may be slightly reduced.

  In the present invention, N-methoxymethylated nylon can be used alone, but in some cases, a crosslinking agent or an acid catalyst can be added. A commercially available material such as a conventionally known melamine resin or isocyanate resin is used as the crosslinking agent, and an acidic catalyst is used as the catalyst, and a general-purpose catalyst such as tartaric acid can be used. However, since the insulating property of the intermediate layer is lowered due to the addition of the acid catalyst, and the effect of suppressing soiling may be reduced, the addition amount needs to be very small. 5 wt% or less is preferable with respect to resin. In some cases, other binder resins can be mixed. As the binder resin that can be mixed, a polyamide resin exhibiting alcohol solubility is used, and the stability of the liquid with time may be increased.

  In addition, it is possible to add a conductive polymer, an acceptor (donor) resin or a low molecular weight compound, and other various additives in accordance with the charge polarity, which may be effective in reducing the residual potential. However, when the upper layer is laminated by dip coating, the additive amount needs to be kept to a minimum because these additives may be dissolved.

  The film thickness of the charge blocking layer is 0.1 μm or more and less than 2.0 μm, preferably about 0.3 μm or more and 2.0 μm or less. When the charge blocking layer becomes thick, the residual potential increases remarkably at low temperatures and low humidity due to repeated charging and exposure, and when the film thickness is too thin, the blocking effect is reduced. Add chemicals, solvents, additives, curing accelerators, etc. necessary for curing (crosslinking), and apply to the substrate by conventional methods such as blade coating, dip coating, spray coating, beat coating, nozzle coating, etc. It is formed. After the coating, it is dried or cured by a curing process such as drying, heating, or light.

  Next, a moiré preventing layer that is effective for reducing moire and reducing the charge potential due to fatigue and residual potential will be described. This moiré preventing layer also has an effect of suppressing scumming, but is required to have a function of preventing moiré or improving the adhesion of the photosensitive layer. Therefore, it is preferable to increase the surface roughness of the moire prevention layer, which is achieved by dispersing the inorganic pigment. The moiré preventing layer has the function of suppressing moire by the inorganic pigment contained as described above, reducing the residual potential and dark decay due to fatigue, and further improving the adhesion to the photosensitive layer.

  The aforementioned moire is a kind of image defect in which interference fringes called moire are formed in an image due to optical interference inside the photosensitive layer when writing with coherent light such as laser light. Basically, it is necessary to contain a material having a large refractive index in order to prevent the occurrence of moire by scattering the incident laser light by this intermediate layer. In order to prevent moiré, a configuration in which an inorganic pigment is dispersed in a binder resin is most effective. In particular, among inorganic pigments, white pigments are effectively used, and for example, titanium oxide, calcium fluoride, calcium oxide, silicon oxide, magnesium oxide, aluminum oxide and the like are favorably used. Among them, titanium oxide having a large hiding power can be most effectively used.

  In addition, the moire prevention layer preferably has a function of moving a charge having the same polarity as the charge charged on the surface of the photoreceptor from the photosensitive layer to the conductive support side from the viewpoint of reducing the residual potential. It also plays a role. For example, in the case of a negatively charged photoreceptor, the residual potential can be greatly reduced by having the intermediate layer have electronic conductivity. As these inorganic pigments, the above-mentioned metal oxides are used effectively, but residual potential can be increased by using low-resistance metal oxides or increasing the addition ratio of metal oxides to the binder resin more than necessary. However, the effect of suppressing soiling may be reduced. Therefore, it is necessary to achieve both suppression of background contamination and reduction of residual potential by properly using them according to the layer structure and film thickness of the intermediate layer in the photoreceptor and adjusting the addition amount. In addition, the use of an electron conductive material (for example, an acceptor) or the like for the moiré preventing layer makes the effects of the present invention more remarkable.

  As the inorganic pigment used in the present invention, the above-mentioned metal oxide is preferably used. However, when a conductive metal oxide is used, it is effective in reducing the residual potential, but the background stain increases. In the case where a metal oxide having a high resistance is used, it is effective in suppressing soil contamination, but there is a tendency that the residual potential tends to increase. In the present invention, since a plurality of intermediate layers composed of a charge blocking layer and a moire preventing layer are formed and functionally separated, an inorganic pigment can be selected in a wider range, but an intermediate containing no inorganic pigment can be selected. Even if it has a layer, the resistance of the inorganic pigment contained in the intermediate layer containing the inorganic pigment has a considerable influence on the soiling and the residual potential. Therefore, it is preferable to use a metal oxide having a higher resistance than a conductive metal oxide in order to suppress soiling, and among these metal oxides, titanium oxide is most preferable from the viewpoint of image quality stability. . As the titanium oxide to be used, high purity is more preferable in reducing the increase in residual potential. The purity is preferably 99.0% or more, and more preferably 99.5% or more.

  The average primary particle size of the inorganic pigment of the present invention is preferably 0.01 μm to 0.8 μm, and more preferably 0.05 μm to 0.5 μm. However, when only an inorganic pigment having an average primary particle size of 0.1 μm or less is used, it is effective for reducing background stains, but the moire prevention effect tends to decrease, while the average primary particle size is When only a metal oxide larger than 0.4 μm is used, although the moire prevention effect is excellent, there is a tendency that the effect of suppressing soiling is somewhat reduced. In this case, by mixing and using inorganic pigments having different average primary particle sizes, it may be possible to achieve both reduction of background stains and reduction of moire, and may be effective in reducing residual potential. It is.

  As the binder resin, the same resin as the charge blocking layer can be used, but considering that the photosensitive layer is laminated on the moire preventing layer, a binder resin that is insoluble in the coating solvent for the photosensitive layer is suitable. These binder resins include water-soluble resins such as polyvinyl alcohol, casein, and sodium polyacrylate, alcohol-soluble resins such as polyamide, copolymer nylon, and methoxymethylated nylon, polyurethane, phenol resin, alkyd-melamine resin, and epoxy resin. And a curable resin that forms a three-dimensional network structure. Among these resins, thermosetting resins are most preferably used because they are hardened so that the influence of elution by an organic solvent is extremely small when the photosensitive layer is applied on the intermediate layer. Among the thermosetting resins, an alkyd / melamine resin mixture is most preferably used in terms of residual potential and environmental stability.

  At this time, the mixing ratio of the alkyd / melamine resin is an important factor that determines the structure and characteristics of the moire prevention layer. A range in which the ratio (weight ratio) between the two is 5/5 to 8/2 can be cited as a good mixing ratio range. When the melamine resin is richer than 5/5, volume shrinkage is increased during thermosetting, and coating film defects are likely to occur, or the residual potential of the photoreceptor is increased. If the alkyd resin is richer than 8/2, it is effective in reducing the residual potential of the photoconductor, but it is not desirable because the bulk resistance becomes too low and the soiling becomes worse.

  In the anti-moire layer, the volume ratio between the inorganic pigment and the binder resin determines an important characteristic. For this reason, it is important that the volume ratio of the inorganic pigment to the binder resin is in the range of 1/1 to 3/1. When the volume ratio of the two is less than 1/1, not only the moire prevention ability is lowered, but there is a case where the increase of the residual potential in repeated use becomes large. On the other hand, in the region where the volume ratio exceeds 3/1, not only the binding ability of the binder resin is inferior, but also the surface property of the coating film is deteriorated, which may adversely affect the film forming property of the upper photosensitive layer. This effect can be a serious problem when the photosensitive layer is a laminated type and a thin layer such as a charge generation layer is formed. When the volume ratio exceeds 3/1, there are cases where the binder resin cannot cover the surface of the inorganic pigment, and the direct contact with the charge generation material increases the probability of heat carrier generation, resulting in soiling. It may have an adverse effect on it.

  Furthermore, by using two types of titanium oxides having different average particle diameters for the moire prevention layer, it is possible to improve the concealing power to the conductive substrate and suppress moire and to cause a pin that causes an abnormal image. The hole can be eliminated. For this purpose, it is important that the ratio of the average particle diameters of the two types of titanium oxide used is within a certain range (0.2 <D2 / D1 ≦ 0.5). In the case of the particle size ratio outside the range specified in the present invention, that is, when the ratio of the average particle size of the other titanium oxide (T2) to the average particle size of the titanium oxide (T1) having the larger average particle size is too small ( When 0.2 ≧ D2 / D1), the activity on the titanium oxide surface is increased, and the electrostatic stability of the electrophotographic photosensitive member is significantly impaired. Further, when the ratio of the average particle diameter of the other titanium oxide (T2) to the average particle diameter of one titanium oxide (T1) is too large (D2 / D1> 0.5), the hiding power to the conductive substrate is lowered. In addition, the suppression of moiré and abnormal images is reduced. The average particle size mentioned here is obtained from a particle size distribution measurement obtained when strong dispersion is performed in an aqueous system.

  Further, the average particle size (D2) of titanium oxide (T2) having a smaller particle size is an important factor, and it is important that 0.05 μm <D2 <0.20 μm. When the thickness is 0.05 μm or less, the hiding power is reduced, and moire may be generated. On the other hand, when the thickness is 0.20 μm or more, the filling rate of the titanium oxide in the moire preventing layer is lowered, and the background dirt suppressing effect cannot be sufficiently exhibited.

The mixing ratio (weight ratio) of the two types of titanium oxide is also an important factor. When T2 / (T1 + T2) is smaller than 0.2, the filling rate of titanium oxide is not so large and the effect of suppressing scumming cannot be exhibited sufficiently. On the other hand, when it is larger than 0.8, the concealing power is reduced, and moire may be generated. Therefore, it is important that 0.2 ≦ T2 / (T1 + T2) ≦ 0.8.
The film thickness of the moire preventing layer is 1 to 10 μm, preferably 2 to 5 μm. If the film thickness is less than 1 μm, the effect is small, and if it exceeds 10 μm, residual potential is accumulated, which is not desirable.

  The inorganic pigment is dispersed together with a solvent and a binder resin by a conventional method, for example, a ball mill, a sand mill, an attrier, etc., and, if necessary, a chemical, a solvent, an additive, a curing accelerator, etc. necessary for curing (crosslinking). In addition, it is formed on the substrate by a blade coating method, a dip coating method, a spray coating method, a beat coating method, a nozzle coating method, or the like by a conventional method. After the coating, it is dried or cured by a curing process such as drying, heating, or light.

Next, the photosensitive layer will be described. The photosensitive layer may be a single-layered photosensitive layer containing a charge generation material and a charge transport material, but as described above, the laminated type composed of the charge generation layer and the charge transport layer has excellent characteristics in sensitivity and durability. Shown and used well.
The charge generation layer is a layer mainly composed of a charge generation material.
A known charge generating material can be used for the charge generation layer, and representative examples thereof include monoazo pigments, disazo pigments, trisazo pigments, perylene pigments, perinone pigments, quinacridone pigments, and quinone condensed polycyclic compounds. Squalic acid dyes, other phthalocyanine pigments, naphthalocyanine pigments, azulenium salt dyes and the like are used. These charge generation materials may be used alone or in combination of two or more.

  In particular, an azo pigment represented by the following formula (XI) or a specific crystal form (at least 27.2 as a diffraction peak (± 0.2 °) at a Bragg angle 2θ with respect to a characteristic X-ray of CuKα (wavelength 1.542 mm)): Since titanyl phthalocyanine (having a maximum diffraction peak at °) has high sensitivity and high durability and is particularly resistant to light fatigue, it can be used effectively in the full-color image forming apparatus of the present invention.

（XI）式中、Ｃｐ₁、Ｃｐ₂はカップラー残基を表す。Ｒ₂₀₁、Ｒ₂₀₂はそれぞれ、水素原子、ハロゲン原子、炭素鎖数１〜４のアルキル基、アルコキシ基、シアノ基のいずれかを表し、同一でも異なっていても良い。またＣｐ₁、Ｃｐ₂は下記（XII）式で表される。

(XI) wherein, Cp _1, Cp ₂ represents a coupler residue. R ₂₀₁ and R ₂₀₂ each represent a hydrogen atom, a halogen atom, an alkyl group having 1 to 4 carbon chains, an alkoxy group, or a cyano group, and may be the same or different. Cp ₁ and Cp ₂ are represented by the following formula (XII).

（XII）式中、Ｒ₂₀₃は、水素原子、メチル基、エチル基などのアルキル基、フェニル基などのアリール基を表す。Ｒ₂₀₄、Ｒ₂₀₅、Ｒ₂₀₆、Ｒ₂₀₇、Ｒ₂₀₈はそれぞれ、水素原子、ニトロ基、シアノ基、フッ素、塩素、臭素、ヨウ素などのハロゲン原子、トリフルオロメチル基、メチル基、エチル基などのアルキル基、メトキシ基、エトキシ基などのアルコキシ基、ジアルキルアミノ基、水酸基を表し、Ｚは置換もしくは無置換の芳香族炭素環または置換もしくは無置換の芳香族複素環を構成するのに必要な原子群を表す。
また、前記（XI）式において、Ｃｐ₁とＣｐ₂が異なるものは前記（XI）式で表される材料の中でも特に高感度を示し、本発明に使用される感光体の電荷発生物質として良好に使用される。

In the formula (XII), 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. _R204 , _R205 , _R206 , _R207 , and _R208 are each a hydrogen atom, a nitro group, a cyano group, a halogen atom such as fluorine, chlorine, bromine, or iodine, a trifluoromethyl group, a methyl group, or an ethyl group. Represents an alkoxy group such as an alkyl group, a methoxy group or an ethoxy group, a dialkylamino group or a hydroxyl group, and Z represents an atom necessary for constituting a substituted or unsubstituted aromatic carbocyclic ring or a substituted or unsubstituted aromatic heterocyclic ring. Represents a group.
Further, in the formula (XI), those in which Cp ₁ and Cp ₂ are different show particularly high sensitivity among the materials represented by the formula (XI), and are good as charge generating materials for the photoreceptor used in the present invention. Used for.

  Among the titanyl phthalocyanines having the maximum diffraction peak at 27.2 °, there are further main peaks at 9.4 °, 9.6 °, and 24.0 °, and the diffraction peak at the lowest angle is 7%. A crystal type titanyl phthalocyanine crystal having a peak at .3 °, no peak between the peak at 7.3 ° and the peak at 9.4 °, and no peak at 26.3 °, In particular, it exhibits high sensitivity, and the decrease in chargeability in repeated use of the photoreceptor is small, so that it can be used favorably as a charge generating material for the photoreceptor used in the present invention.

  As described above, the effect of suppressing scumming is remarkably enhanced by laminating the charge blocking layer and the moire preventing layer, but these effects are due to the suppression of charge injection from the conductive support. It is necessary to take another measure against the soiling caused by the aggregation of the charge generation layer formed thereon and the decrease in purity. For this reason, controlling the particle size of these charge generation materials to be very small is effective in suppressing scumming. When synthesizing these charge generation materials, the particle size can be controlled by synthesizing a small primary particle size or removing coarse particles by filtering the dispersion after dispersion.

The charge generation layer is obtained by dispersing the pigment in a suitable solvent together with a binder resin as necessary using a ball mill, an attritor, a sand mill, an ultrasonic wave, etc. It is formed.
As the binder resin used for the charge generation layer as necessary, polyamide, polyurethane, epoxy resin, polyketone, polycarbonate, silicone resin, acrylic resin, polyvinyl butyral, polyvinyl formal, polyvinyl ketone, polystyrene, polysulfone, poly-N- Vinyl carbazole, polyacrylamide, polyvinyl benzal, polyester, phenoxy resin, vinyl chloride-vinyl acetate copolymer, polyvinyl acetate, polyphenylene oxide, polyamide, polyvinyl pyridine, cellulosic resin, casein, polyvinyl alcohol, polyvinyl pyrrolidone, etc. It is done. The amount of the binder resin is suitably 0 to 500 parts by weight, preferably 10 to 300 parts by weight with respect to 100 parts by weight of the charge generating material.

  Examples of the solvent used here include isopropanol, acetone, methyl ethyl ketone, cyclohexanone, tetrahydrofuran, dioxane, ethyl cellosolve, ethyl acetate, methyl acetate, dichloromethane, dichloroethane, monochlorobenzene, cyclohexane, toluene, xylene, ligroin and the like. As a coating method for the coating solution, a dip coating method, spray coating, beat coating, nozzle coating, spinner coating, ring coating, or the like can be used. The thickness of the charge generation layer is suitably about 0.01 to 5 μm, preferably 0.1 to 2 μm.

The charge transport layer can be formed by dissolving or dispersing a charge transport material and a binder resin in an appropriate solvent, and applying and drying the solution on the charge generation layer. Moreover, a plasticizer, a leveling agent, antioxidant, etc. can also be added as needed.
Charge transport materials include hole transport materials and electron transport materials. Examples of hole transport materials include poly-N-vinylcarbazole and derivatives thereof, poly-γ-carbazolylethyl glutamate and derivatives thereof, pyrene-formaldehyde condensates and derivatives thereof, polyvinylpyrene, polyvinylphenanthrene, polysilane, oxazole derivatives, Oxadiazole derivatives, imidazole derivatives, monoarylamine derivatives, diarylamine derivatives, triarylamine derivatives, stilbene derivatives, α-phenylstilbene derivatives, benzidine derivatives, diarylmethane derivatives, triarylmethane derivatives, 9-styrylanthracene derivatives, pyrazolines Derivatives, divinylbenzene derivatives, hydrazone derivatives, indene derivatives, butadiene derivatives, pyrene derivatives, etc., bisstilbene derivatives, enamine derivatives, etc. Other known materials may be mentioned. These charge transport materials may be used alone or in combination of two or more.

  Examples of the electron transporting material include chloroanil, bromoanil, 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] thiophen-4-one, 1,3,7-tri Examples thereof include electron-accepting substances such as nitrodibenzothiophene-5,5-dioxide and benzoquinone derivatives.

  The binder resin is polystyrene, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer, polyester, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, polyvinyl acetate, poly Vinylidene chloride, polyarate, phenoxy resin, polycarbonate, cellulose acetate resin, ethyl cellulose resin, polyvinyl butyral, polyvinyl formal, polyvinyl toluene, poly-N-vinylcarbazole, acrylic resin, silicone resin, epoxy resin, melamine resin, urethane resin, phenol resin And thermoplastic or thermosetting resins such as alkyd resins.

  The amount of the charge transport material is appropriately 20 to 300 parts by weight, preferably 40 to 150 parts by weight, based on 100 parts by weight of the binder resin. The thickness of the charge transport layer is preferably about 5 to 100 μm.

  As the solvent used here, tetrahydrofuran, dioxane, toluene, dichloromethane, monochlorobenzene, dichloroethane, cyclohexanone, methyl ethyl ketone, acetone and the like are used. Among them, the use of a non-halogen solvent is desirable for the purpose of reducing the environmental load. Specifically, cyclic ethers such as tetrahydrofuran, dioxolane and dioxane, aromatic hydrocarbons such as toluene and xylene, and derivatives thereof are preferably used.

  In addition, a polymer charge transport material having a function as a charge transport material and a function of a binder resin is also preferably used for the charge transport layer. Since the charge transport layer composed of these polymer charge transport materials does not dissolve when a protective layer described later is laminated, the function of the protective layer becomes even more remarkable. As the polymer charge transport material, known materials can be used, and in particular, a polycarbonate containing a triarylamine structure in the main chain and / or side chain is preferably used. Among these, polymer charge transport materials represented by the formulas (I) to (X) are preferably used, and these are exemplified below and specific examples are shown.

（Ｉ）式中、Ｒ₁、Ｒ₂、Ｒ₃はそれぞれ独立して置換もしくは無置換のアルキル基又はハロゲン原子、Ｒ₄は水素原子又は置換もしくは無置換のアルキル基、Ｒ₅、Ｒ₆は置換もしくは無置換のアリール基、ｏ、ｐ、ｑはそれぞれ独立して０〜４の整数、ｋ、ｊは組成を表し、０．１≦ｋ≦１、０≦ｊ≦０．９、ｎは繰り返し単位数を表し５〜５０００の整数である。Ｘは脂肪族の２価基、環状脂肪族の２価基、または下記一般式で表される２価基を表す。尚、（Ｉ）式は２つの共重合種が交互共重合体の形で記載されているが、ランダム共重合体でも構わない。

(I) In the formula, R ₁ , R ₂ and R ₃ are each independently a substituted or unsubstituted alkyl group or a halogen atom, R ₄ is a hydrogen atom or a substituted or unsubstituted alkyl group, R ₅ and R ₆ are A substituted or unsubstituted aryl group, o, p, q are each independently an integer of 0-4, k, j represents a composition, 0.1 ≦ k ≦ 1, 0 ≦ j ≦ 0.9, n is It represents the number of repeating units and is an integer of 5 to 5000. X represents an aliphatic divalent group, a cycloaliphatic divalent group, or a divalent group represented by the following general formula. In the formula (I), two copolymer species are described in the form of an alternating copolymer, but a random copolymer may be used.

Ｒ₁₀₁、Ｒ₁₀₂は各々独立して置換もしくは無置換のアルキル基、アリール基またはハロゲン原子を表す。ｌ、ｍは０〜４の整数、Ｙは単結合、炭素原子数１〜１２の直鎖状、分岐状もしくは環状のアルキレン基、−Ｏ−、−Ｓ−、−ＳＯ−、−ＳＯ_２−、−ＣＯ−、−ＣＯ−Ｏ−Ｚ−Ｏ−ＣＯ−（式中Ｚは脂肪族の２価基を表す。）または、

（ａは１〜２０の整数、ｂは１〜２０００の整数、Ｒ₁₀₃、Ｒ₁₀₄は置換または無置換のアルキル基又はアリール基を表す）を表す。ここで、Ｒ₁₀₁とＲ₁₀₂、Ｒ₁₀₃とＲ₁₀₄は、それぞれ同一でも異なってもよい。）

R ₁₀₁ and R ₁₀₂ each independently represents a substituted or unsubstituted alkyl group, aryl group or halogen atom. l and m are integers of 0 to 4, Y is a single bond, a linear, branched or cyclic alkylene group having 1 to 12 carbon atoms, —O—, —S—, —SO—, —SO ₂ —. , -CO-, -CO-O-Z-O-CO- (wherein Z represents an aliphatic divalent group) or

(A represents an integer of 1 to 20, b represents an integer of 1 to 2000, and R ₁₀₃ and R ₁₀₄ represent a substituted or unsubstituted alkyl group or aryl group). Here, R ₁₀₁ and R ₁₀₂ , and R ₁₀₃ and R ₁₀₄ may be the same or different. )

（II）式中、Ｒ₇、Ｒ₈は置換もしくは無置換のアリール基、Ａｒ₁、Ａｒ₂、Ａｒ₃は同一又は異なるアリレン基を表す。Ｘ、ｋ、ｊおよびｎは、（Ｉ）式の場合と同じである。尚、（II）式は２つの共重合種が交互共重合体の形で記載されているが、ランダム共重合体でも構わない。

(II) In the formula, R ₇ and R ₈ represent a substituted or unsubstituted aryl group, and Ar ₁ , Ar ₂ , and Ar ₃ represent the same or different arylene groups. X, k, j and n are the same as those in the formula (I). In the formula (II), two copolymer species are described in the form of an alternating copolymer, but a random copolymer may be used.

（III）式中、Ｒ₉、Ｒ₁₀は置換もしくは無置換のアリール基、Ａｒ₄、Ａｒ₅、Ａｒ₆は同一又は異なるアリレン基を表す。Ｘ、ｋ、ｊおよびｎは、（Ｉ）式の場合と同じである。尚、（III）式は２つの共重合種が交互共重合体の形で記載されているが、ランダム共重合体でも構わない。

(III) In the formula, R ₉ and R ₁₀ represent a substituted or unsubstituted aryl group, and Ar ₄ , Ar ₅ and Ar ₆ represent the same or different arylene groups. X, k, j and n are the same as those in the formula (I). In the formula (III), two copolymer species are described in the form of an alternating copolymer, but a random copolymer may be used.

（IV）式中、Ｒ₁₁、Ｒ₁₂は置換もしくは無置換のアリール基、Ａｒ₇、Ａｒ₈、Ａｒ₉は同一又は異なるアリレン基、ｐは１〜５の整数を表す。Ｘ、ｋ、ｊおよびｎは、（Ｉ）式の場合と同じである。尚、（IV）式は２つの共重合種が交互共重合体の形で記載されているが、ランダム共重合体でも構わない。

(IV) In the formula, R ₁₁ and R ₁₂ are substituted or unsubstituted aryl groups, Ar ₇ , Ar ₈ and Ar ₉ are the same or different arylene groups, and p represents an integer of 1 to 5. X, k, j and n are the same as those in the formula (I). In the formula (IV), two copolymer species are described in the form of an alternating copolymer, but a random copolymer may be used.

（Ｖ）式中、Ｒ₁₃、Ｒ₁₄は置換もしくは無置換のアリール基、Ａｒ₁₀、Ａｒ₁₁、Ａｒ₁₂は同一又は異なるアリレン基、Ｘ₁、Ｘ₂は置換もしくは無置換のエチレン基、又は置換もしくは無置換のビニレン基を表す。Ｘ、ｋ、ｊおよびｎは、（Ｉ）式の場合と同じである。尚、（Ｖ）式は２つの共重合種が交互共重合体の形で記載されているが、ランダム共重合体でも構わない。

(V) In the formula, R ₁₃ and R ₁₄ are substituted or unsubstituted aryl groups, Ar ₁₀ , Ar ₁₁ and Ar ₁₂ are the same or different arylene groups, X ₁ and X ₂ are substituted or unsubstituted ethylene groups, or A substituted or unsubstituted vinylene group is represented. X, k, j and n are the same as those in the formula (I). In the formula (V), two copolymer species are described in the form of an alternating copolymer, but a random copolymer may be used.

（VI）式中、Ｒ₁₅、Ｒ₁₆、Ｒ₁₇、Ｒ₁₈は置換もしくは無置換のアリール基、Ａｒ₁₃、Ａｒ₁₄、Ａｒ₁₅、Ａｒ₁₆は同一又は異なるアリレン基、Ｙ₁、Ｙ₂、Ｙ₃は単結合、置換もしくは無置換のアルキレン基、置換もしくは無置換のシクロアルキレン基、置換もしくは無置換のアルキレンエーテル基、酸素原子、硫黄原子、ビニレン基を表し同一であっても異なってもよい。Ｘ、ｋ、ｊおよびｎは、（Ｉ）式の場合と同じである。尚、（VI）式は２つの共重合種が交互共重合体の形で記載されているが、ランダム共重合体でも構わない。

(VI) In the formula, R ₁₅ , R ₁₆ , R ₁₇ and R ₁₈ are substituted or unsubstituted aryl groups, Ar ₁₃ , Ar ₁₄ , Ar ₁₅ and Ar ₁₆ are the same or different arylene groups, Y ₁ , Y ₂ , Y ₃ represents a single bond, a substituted or unsubstituted alkylene group, a substituted or unsubstituted cycloalkylene group, a substituted or unsubstituted alkylene ether group, an oxygen atom, a sulfur atom, or a vinylene group, which may be the same or different. Good. X, k, j and n are the same as those in the formula (I). In the formula (VI), two copolymer species are described in the form of an alternating copolymer, but a random copolymer may be used.

（VII）式中、Ｒ₁₉、Ｒ₂₀は水素原子、置換もしくは無置換のアリール基を表し、Ｒ₁₉とＲ₂₀は環を形成していてもよい。Ａｒ₁₇、Ａｒ₁₈、Ａｒ₁₉は同一又は異なるアリレン基を表す。Ｘ、ｋ、ｊおよびｎは、（Ｉ）式の場合と同じである。尚、（VII）式は２つの共重合種が交互共重合体の形で記載されているが、ランダム共重合体でも構わない。

In the formula (VII), R ₁₉ and R ₂₀ represent a hydrogen atom or a substituted or unsubstituted aryl group, and R ₁₉ and R ₂₀ may form a ring. Ar ₁₇ , Ar ₁₈ and Ar ₁₉ represent the same or different arylene groups. X, k, j and n are the same as those in the formula (I). In the formula (VII), two copolymer species are described in the form of an alternating copolymer, but a random copolymer may be used.

（VIII）式中、Ｒ₂₁は置換もしくは無置換のアリール基、Ａｒ₂₀、Ａｒ₂₁、Ａｒ₂₂、Ａｒ₂₃は同一又は異なるアリレン基を表す。Ｘ、ｋ、ｊおよびｎは、（Ｉ）式の場合と同じである。尚、（VIII）式は２つの共重合種が交互共重合体の形で記載されているが、ランダム共重合体でも構わない。

(VIII) In the formula, R ₂₁ represents a substituted or unsubstituted aryl group, and Ar ₂₀ , Ar ₂₁ , Ar ₂₂ , and Ar ₂₃ represent the same or different arylene groups. X, k, j and n are the same as those in the formula (I). In the formula (VIII), two copolymer species are described in the form of an alternating copolymer, but a random copolymer may be used.

（IX）式中、Ｒ₂₂、Ｒ₂₃、Ｒ₂₄、Ｒ₂₅は置換もしくは無置換のアリール基、Ａｒ₂₄、Ａｒ₂₅、Ａｒ₂₆、Ａｒ₂₇、Ａｒ₂₈は同一又は異なるアリレン基を表す。Ｘ、ｋ、ｊおよびｎは、（Ｉ）式の場合と同じである。尚、（IX）式は２つの共重合種が交互共重合体の形で記載されているが、ランダム共重合体でも構わない。

(IX) In the formula, R ₂₂ , R ₂₃ , R ₂₄ and R ₂₅ represent a substituted or unsubstituted aryl group, and Ar ₂₄ , Ar ₂₅ , Ar ₂₆ , Ar ₂₇ and Ar ₂₈ represent the same or different arylene groups. X, k, j and n are the same as those in the formula (I). In the formula (IX), two copolymer species are described in the form of an alternating copolymer, but a random copolymer may be used.

（Ｘ）式中、Ｒ₂₆、Ｒ₂₇は置換もしくは無置換のアリール基、Ａｒ₂₉、Ａｒ₃₀、Ａｒ₃₁は同一又は異なるアリレン基を表す。Ｘ、ｋ、ｊおよびｎは、（Ｉ）式の場合と同じである。尚、（Ｘ）式は２つの共重合種が交互共重合体の形で記載されているが、ランダム共重合体でも構わない。

(X) In the formula, R ₂₆ and R ₂₇ represent a substituted or unsubstituted aryl group, Ar ₂₉ , Ar ₃₀ and Ar ₃₁ represent the same or different arylene groups. X, k, j and n are the same as those in the formula (I). In the formula (X), two copolymer species are described in the form of an alternating copolymer, but a random copolymer may be used.

Further, as the polymer charge transport material used in the charge transport layer, in addition to the polymer charge transport material described above, in the state of the monomer or oligomer having an electron donating group at the time of film formation of the charge transport layer, A polymer having a two-dimensional or three-dimensional crosslinked structure can be finally included by carrying out a curing reaction or a crosslinking reaction.
A charge transport layer composed of a polymer having these electron donating groups is a high molecular compound, so it has excellent film forming properties, and has a charge transport site compared to a charge transport layer composed of a low molecular dispersion type polymer. It can be configured at high density and has excellent charge transport capability. For this reason, a photoreceptor having a charge transport layer using a polymer charge transport material can be expected to have a high speed response.

  Examples of other polymers having an electron donating group include known monomer copolymers, block polymers, graft polymers, star polymers, and, for example, Patent Document 45, Patent Document 46, Patent Document 47, and the like. It is also possible to use a cross-linked polymer having an electron-donating group as disclosed in JP-A No. 11-133.

  In the present invention, a plasticizer or a leveling agent may be added to the charge transport layer. As the plasticizer, those used as general plasticizers such as dibutyl phthalate and dioctyl phthalate can be used as they are, and the amount used is suitably about 0 to 30% by weight based on the binder resin. As the leveling agent, silicone oils such as dimethyl silicone oil and methylphenyl silicone oil, polymers or oligomers having a perfluoroalkyl group in the side chain are used, and the amount used is 0 to 0 with respect to the binder resin. 1% by weight is suitable.

  So far, the case where the photosensitive layer has a laminated structure has been described. However, in the present invention, the photosensitive layer may have a single layer structure. In order to make the photosensitive layer as a single layer, the photosensitive layer is constituted by providing a single layer containing at least the above-described charge generating substance and binder resin, and the binder resin is described in the explanation of the charge generating layer and the charge transport layer. The materials mentioned are used successfully. In addition, when a charge transport material is used in combination with the single-layer photosensitive layer, high photosensitivity, high charge transportability, and low residual potential are expressed and can be used favorably. At this time, as the charge transport material to be used, either a hole transport material or an electron transport material is selected according to the polarity charged on the surface of the photoreceptor. Furthermore, since the above-described polymer charge transporting material also has the functions of a binder resin and a charge transporting material, it is favorably used for a single-layer photosensitive layer.

Next, the protective layer used in the present invention will be described.
The electrophotographic photosensitive member used in the present invention reduces the influence of abrasion caused by repeated use of the photosensitive member, improves the aging stain stability, and further improves electrostatic stability and image quality stability over time. For the purpose of achieving both stability and durability, it is formed by curing at least a trifunctional or higher radical polymerizable monomer having no charge transport structure and a radical polymerizable compound having a monofunctional charge transport structure. A protective layer is provided on the photosensitive layer.

The main purpose of this protective layer is to increase the abrasion resistance of the photoreceptor, but this makes it possible to suppress an increase in electric field strength due to repeated use, and is effective in suppressing scumming. In addition, there is little increase in residual potential, high scratch resistance on the surface of the photoreceptor, and filming and the like are less likely to occur, so it has the effect of reducing the occurrence of image defects and is effective in realizing high durability. Useful.
Scratches formed on the surface of the photosensitive member and foreign matters (toner, toner external additives, carrier, paper dust, etc.) adhering to the surface decrease the cleaning property of the photosensitive member and significantly reduce the image quality stability. Therefore, in order to achieve high durability of the photoconductor, it is important not only to increase the wear resistance, but also to minimize the effects of scratches and filming on the surface of the photoconductor. It is preferable to form a highly elastic and smooth surface layer.

The protective layer used in the present invention is formed by curing at least a trifunctional or higher-functional radical polymerizable monomer having no charge transport structure and a radical polymerizable compound having a monofunctional charge transport structure.
This protective layer has a cross-linked structure obtained by curing a tri- or higher-functional radically polymerizable monomer, so that a three-dimensional network structure is developed, and a highly hard and highly elastic surface layer having a very high cross-linking density can be obtained. In addition, smoothness is high, and high wear resistance and scratch resistance are achieved. In this way, it is important to increase the crosslink density on the surface of the photoreceptor, that is, the number of crosslink bonds per unit volume. However, since a large number of bonds are instantaneously formed in the curing reaction, internal stress due to volume shrinkage occurs. This internal stress increases as the thickness of the protective layer increases. Therefore, if the entire protective layer is cured, cracks and film peeling are likely to occur. Even if this phenomenon does not appear initially, it may be likely to occur over time due to repeated use in the electrophotographic process and the influence of charging, development, transfer, cleaning hazards and thermal fluctuations.

  Methods for solving this problem include (1) introducing a polymer component into the protective layer and the crosslinked structure, (2) using a large amount of monofunctional and bifunctional radically polymerizable monomers, and (3) flexible groups. Although the directionality which softens a protective layer, such as using the polyfunctional monomer which has is mentioned, the crosslinking density of a protective layer becomes thin in any case, and remarkable abrasion resistance is not achieved. On the other hand, the photoreceptor of the present invention is provided with a protective layer having a high crosslinking density with a three-dimensional network structure developed on the charge transport layer, preferably with a film thickness of 1 μm or more and 10 μm or less. No film peeling occurs and very high wear resistance is achieved. By making the film thickness of the protective layer 2 μm or more and 8 μm or less, it is possible to select a material having a higher crosslink density that leads to further improvement in wear resistance in addition to improving the margin for the above problem. Become.

  The reason why the photoconductor used in the present invention can suppress cracks and film peeling is that the protective layer can be made thin, so that the internal stress does not increase, and since the lower layer has a photosensitive layer or a charge transport layer, the surface protective layer This is because internal stress can be relaxed. For this reason, it is not necessary to contain a large amount of polymer material in the protective layer, and the reaction between the polymer material and the radical polymerizable composition (radical polymerizable monomer or radical polymerizable compound having a charge transporting structure) that occurs at this time Scratches and toner filming due to incompatibility with the resulting cured product hardly occur. Further, when the thick film over the entire protective layer is cured by irradiation with light energy, the light transmission from the absorption by the charge transporting structure is limited, and the curing reaction may not sufficiently proceed. In the protective layer of the present invention, preferably a thin film having a thickness of 10 μm or less causes a uniform curing reaction to proceed to the inside, and high wear resistance is maintained inside as well as the surface. In addition, in the formation of the protective layer of the present invention, in addition to the above trifunctional radical polymerizable monomer, a radical polymerizable compound having a monofunctional charge transporting structure is contained, which is a trifunctional or higher functional radical. It is incorporated into the cross-linking bond when the polymerizable monomer is cured. On the other hand, when a low molecular charge transport material having no functional group is contained in the protective layer, the low compatibility of the low molecular charge transport material and white turbidity occur due to its low compatibility. Also decreases. On the other hand, when a bifunctional or higher-functional charge transporting compound is used as the main component, the crosslink structure is fixed by a plurality of bonds and the crosslink density is further increased. However, the charge transporting structure is very bulky, so that the cured resin structure is distorted. Becomes very large, which increases the internal stress of the protective layer.

  Furthermore, the photoreceptor used in the present invention has good electrical characteristics, and therefore has excellent repeated stability, realizing high durability and high stability. This is because a radically polymerizable compound having a monofunctional charge transporting structure is used as a constituent material of the protective layer, and is immobilized in a pendant shape between crosslinks. As described above, the charge transport material having no functional group causes precipitation and clouding phenomenon, and the electrical characteristics are remarkably deteriorated in repeated use such as reduction in sensitivity and increase in residual potential. When a bifunctional or higher-functional charge transporting compound is used as the main component, it is fixed in the crosslinked structure with a plurality of bonds, so the intermediate structure (cation radical) during charge transport cannot be kept stable, Sensitivity decreases due to traps and residual potential increases. Such deterioration of the electric characteristics appears as an image such as a decrease in image density and thinning of characters. Furthermore, in the photoconductor of the present invention, a high mobility design with less charge trapping of the conventional photoconductor can be applied as the lower charge transport layer, and the electrical side effects of the protective layer can be minimized.

  Furthermore, in the formation of the protective layer of the present invention, the protective layer is made insoluble in an organic solvent, so that particularly remarkable wear resistance is exhibited. The protective layer of the present invention is formed by curing a tri- or higher-functional radical polymerizable monomer having no charge transporting structure and a radical polymerizable compound having a monofunctional charge transporting structure. Although the network structure is developed and has a high crosslink density, contents other than the above components (for example, mono- or bifunctional monomers, polymer binders, antioxidants, leveling agents, plasticizers and other additives, and dissolution from lower layers) Depending on the component) and curing conditions, the cross-linking density may be locally dilute or may be formed as an aggregate of fine cured products cross-linked with high density. Such a protective layer has low bonding strength between cured products and is soluble in organic solvents, and is repeatedly used in the electrophotographic process. Separation is likely to occur. By making the protective layer insoluble in the organic solvent as in the present invention, the original three-dimensional network structure is developed and has a high degree of crosslinking, and the chain reaction proceeds in a wide range and the cured product has a high molecular weight. Therefore, a dramatic improvement in wear resistance is achieved.

Next, the constituent material of the protective layer coating solution of the present invention will be described.
The trifunctional or higher functional radical polymerizable monomer having no charge transporting structure used in the present invention is a hole transporting structure such as triarylamine, hydrazone, pyrazoline, carbazole, such as condensed polycyclic quinone, diphenoquinone, cyano. A monomer having no electron transport structure such as an electron-withdrawing aromatic ring having a group or a nitro group and having three or more radically polymerizable functional groups. The radical polymerizable functional group may be any group as long as it has a carbon-carbon double bond and is capable of radical polymerization. Examples of these radical polymerizable functional groups include 1-substituted ethylene functional groups and 1,1-substituted ethylene functional groups shown below.

(1) Examples of the 1-substituted ethylene functional group include functional groups represented by the following formulas.
CH ₂ = CH—X ₁ −... Formula 10
(However, in Formula 10, X ₁ represents an arylene group such as an optionally substituted phenylene group or naphthylene group, an optionally substituted alkenylene group, —CO— group, —COO— Group, —CON (R ₁₀ ) — group (R ₁₀ is an alkyl group such as hydrogen, methyl group or ethyl group, an aralkyl group such as benzyl group, naphthylmethyl group or phenethyl group, or an aryl group such as phenyl group or naphthyl group. Represents a -S- group.)
Specific examples of these functional groups include vinyl group, styryl group, 2-methyl-1,3-butadienyl group, vinylcarbonyl group, acryloyloxy group, acryloylamide group, vinylthioether group and the like.

(2) Examples of the 1,1-substituted ethylene functional group include functional groups represented by the following formulas.
CH ₂ = C (Y) -X ₂ -... Formula 11
(However, in Formula 11, Y is an alkyl group which may have a substituent, an aralkyl group which may have a substituent, a phenyl group which may have a substituent, a naphthyl group, etc. An aryl group, a halogen atom, a cyano group, an nitro group, an alkoxy group such as a methoxy group or an ethoxy group, a -COOR ₁₁ group (R ₁₁ is a hydrogen atom, an optionally substituted methyl group, an ethyl group, etc. An alkyl group, an optionally substituted benzyl, an aralkyl group such as a phenethyl group, an optionally substituted phenyl group, an aryl group such as a naphthyl group, or -CONR ₁₂ R ₁₃ (R ₁₂ and R ₁₃ represents a hydrogen atom, an optionally substituted alkyl group such as a methyl group or an ethyl group, an optionally substituted benzyl group, a naphthylmethyl group, or an aralkyl group such as a phenethyl group; Ma Is a phenyl group which may have a substituent, an aryl group such as phenyl or naphthyl, which may be the same or different from each other.) Further, X ₂ is and the same substituents as X ₁ in the formula 10 Represents a single bond or an alkylene group, provided that at least one of Y and X ₂ is an oxycarbonyl group, a cyano group, an alkenylene group, and an aromatic ring.)

Specific examples of these functional groups include an α-acryloyloxy chloride group, a methacryloyloxy group, an α-cyanoethylene group, an α-cyanoacryloyloxy group, an α-cyanophenylene group, and a methacryloylamino group.
In addition, examples of the substituent further substituted with the substituent for X ₁ , X ₂ , and Y include, for example, a halogen atom, a nitro group, a cyano group, a methyl group, an alkyl group such as an ethyl group, a methoxy group, an ethoxy group, and the like And an aryloxy group such as a phenoxy group, an aryl group such as a phenyl group and a naphthyl group, and an aralkyl group such as a benzyl group and a phenethyl group.

  Among these radical polymerizable functional groups, acryloyloxy group and methacryloyloxy group are particularly useful, and a compound having three or more acryloyloxy groups is, for example, a compound having three or more hydroxyl groups in the molecule and an acrylic group. It can be obtained by using an acid (salt), an acrylic acid halide, or an acrylic ester to cause an ester reaction or a transesterification reaction. A compound having three or more methacryloyloxy groups can be obtained in the same manner. Further, the radical polymerizable functional groups in the monomer having three or more radical polymerizable functional groups may be the same or different.

Specific examples of the trifunctional or higher functional radical polymerizable monomer having no charge transporting structure include the following, but are not limited to these compounds.
That is, examples of the radical polymerizable monomer used in the present invention include trimethylolpropane triacrylate (TMPTA), trimethylolpropane trimethacrylate, trimethylolpropane alkylene-modified triacrylate, trimethylolpropane ethyleneoxy-modified (hereinafter referred to as EO modification). ) Triacrylate, trimethylolpropane propyleneoxy modified (hereinafter PO modified) triacrylate, trimethylolpropane caprolactone modified triacrylate, trimethylolpropane alkylene modified trimethacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate (PETTA), glycerol triacrylate Glycerol epichlorohydrin modified (hereinafter ECH modified) Acrylate, glycerol EO modified triacrylate, glycerol PO modified triacrylate, tris (acryloxyethyl) isocyanurate, dipentaerythritol hexaacrylate (DPHA), dipentaerythritol caprolactone modified hexaacrylate, dipentaerythritol hydroxypentaacrylate, alkylated di Pentaerythritol pentaacrylate, alkylated dipentaerythritol tetraacrylate, alkylated dipentaerythritol triacrylate, dimethylolpropane tetraacrylate (DTMPTA), pentaerythritol ethoxytetraacrylate, phosphoric acid EO-modified triacrylate, 2, 2, 5, 5 , -Tetrahydroxymethylcyclopentanone tetraacrylate And the like, which can be used in combination either alone or in combination.

  The trifunctional or higher functional radical polymerizable monomer having no charge transporting structure used in the present invention is a ratio of molecular weight to the number of functional groups in the monomer in order to form a dense crosslink in the protective layer ( The molecular weight / number of functional groups) is preferably 250 or less. Further, when this ratio is larger than 250, the protective layer is soft and the wear resistance tends to be somewhat lowered. Therefore, among the monomers exemplified above, among monomers having a modifying group such as EO, PO, caprolactone, etc. It is not preferable to use a compound having an extremely long modifying group alone. Further, the proportion of the trifunctional or higher functional radical polymerizable monomer having no charge transporting structure used in the protective layer is 20 to 80% by weight, preferably 30 to 70% by weight, based on the total amount of the protective layer. When the monomer component is less than 20% by weight, the three-dimensional cross-linking density of the protective layer is small, and it is difficult to achieve a dramatic improvement in wear resistance as compared with the case of using a conventional thermoplastic binder resin. On the other hand, when it exceeds 80% by weight, the content of the charge transporting compound is lowered, and the electrical characteristics tend to be deteriorated. The electrical properties and abrasion resistance required differ depending on the process used, and the film thickness of the protective layer of the photoconductor varies accordingly. The range of is most preferable.

  The radical polymerizable compound having a monofunctional charge transporting structure used in the protective layer of the present invention is a hole transporting structure such as triarylamine, hydrazone, pyrazoline, carbazole, such as condensed polycyclic quinone, diphenoquinone, It refers to a compound having an electron transport structure such as an electron-withdrawing aromatic ring having a cyano group or a nitro group, and having one radical polymerizable functional group. Examples of the radical polymerizable functional group include those shown in the above radical polymerizable monomer, and acryloyloxy group and methacryloyloxy group are particularly useful. In addition, a triarylamine structure is highly effective as a charge transporting structure, and in particular, when a compound represented by the structure of the following general formula (1) or (2) is used, electrical characteristics such as sensitivity and residual potential are obtained. Is well maintained.

｛式中、Ｒ₁は水素原子、ハロゲン原子、置換基を有してもよいアルキル基、置換基を有してもよいアラルキル基、置換基を有してもよいアリール基、シアノ基、ニトロ基、アルコキシ基、−ＣＯＯＲ₇（Ｒ₇は水素原子、置換基を有してもよいアルキル基、置換基を有してもよいアラルキル基又は置換基を有してもよいアリール基）、ハロゲン化カルボニル基若しくはＣＯＮＲ₈Ｒ₉（Ｒ₈及びＲ₉は水素原子、ハロゲン原子、置換基を有してもよいアルキル基、置換基を有してもよいアラルキル基又は置換基を有してもよいアリール基を示し、互いに同一であっても異なっていてもよい）を表わし、Ａｒ₁、Ａｒ₂は置換もしくは無置換のアリーレン基を表わし、同一であっても異なってもよい。Ａｒ₃、Ａｒ₄は置換もしくは無置換のアリール基を表わし、同一であっても異なってもよい。Ｘは単結合、置換もしくは無置換のアルキレン基、置換もしくは無置換のシクロアルキレン基、置換もしくは無置換のアルキレンエーテル基、酸素原子、硫黄原子、ビニレン基を表わす。Ｚは置換もしくは無置換のアルキレン基、置換もしくは無置換のアルキレンエーテル２価基、アルキレンオキシカルボニル２価基を表わす。ｍ、ｎは０〜３の整数を表わす。｝

{In the formula, R ₁ represents a hydrogen atom, a halogen atom, an alkyl group which may have a substituent, an aralkyl group which may have a substituent, an aryl group which may have a substituent, a cyano group, a nitro group, Group, alkoxy group, —COOR ₇ (R ₇ is a hydrogen atom, an alkyl group which may have a substituent, an aralkyl group which may have a substituent or an aryl group which may have a substituent), halogen Carbonyl group or CONR ₈ R ₉ (R ₈ and R ₉ may have a hydrogen atom, a halogen atom, an alkyl group which may have a substituent, an aralkyl group which may have a substituent, or a substituent. Represents a good aryl group, which may be the same or different, and Ar ₁ and Ar ₂ represent a substituted or unsubstituted arylene group, which may be the same or different. Ar ₃ and Ar ₄ represent a substituted or unsubstituted aryl group, and may be the same or different. X represents a single bond, a substituted or unsubstituted alkylene group, a substituted or unsubstituted cycloalkylene group, a substituted or unsubstituted alkylene ether group, an oxygen atom, a sulfur atom, or a vinylene group. Z represents a substituted or unsubstituted alkylene group, a substituted or unsubstituted alkylene ether divalent group, or an alkyleneoxycarbonyl divalent group. m and n represent an integer of 0 to 3. }

Specific examples of general formulas (1) and (2) are shown below.
In the general formulas (1) and (2), in the substituent of R ₁ , examples of the alkyl group include a methyl group, an ethyl group, a propyl group, and a butyl group, and examples of the aryl group include a phenyl group and a naphthyl group. The aralkyl group includes a benzyl group, a phenethyl group, and a naphthylmethyl group, and the alkoxy group includes a methoxy group, an ethoxy group, a propoxy group, and the like. These include a halogen atom, a nitro group, a cyano group, and a methyl group. Substituted with an alkyl group such as an ethyl group, an alkoxy group such as a methoxy group or an ethoxy group, an aryloxy group such as a phenoxy group, an aryl group such as a phenyl group or a naphthyl group, an aralkyl group such as a benzyl group or a phenethyl group, etc. May be.
Among the substituents for R ₁ , particularly preferred are a hydrogen atom and a methyl group.

Ar ₃ and Ar ₄ represent a substituted or unsubstituted aryl group, and examples of the aryl group include a condensed polycyclic hydrocarbon group, a non-fused cyclic hydrocarbon group, and a heterocyclic group.
The condensed polycyclic hydrocarbon group preferably has 18 or less carbon atoms forming a ring, for example, a pentanyl group, an indenyl group, a naphthyl group, an azulenyl group, a heptaenyl group, a biphenylenyl group, an as-indacenyl group. , S-indacenyl group, fluorenyl group, acenaphthylenyl group, preadenyl group, acenaphthenyl group, phenalenyl group, phenanthryl group, anthryl group, fluoranthenyl group, acephenanthrenyl group, aceanthrylenyl group, triphenylyl group, pyrenyl group , A chrycenyl group, a naphthacenyl group, and the like.

Examples of the non-fused cyclic hydrocarbon group include monovalent groups of monocyclic hydrocarbon compounds such as benzene, diphenyl ether, polyethylene diphenyl ether, diphenyl thioether and diphenyl sulfone, or biphenyl, polyphenyl, diphenylalkane, diphenylalkene, diphenylalkyne, Monovalent groups of non-condensed polycyclic hydrocarbon compounds such as triphenylmethane, distyrylbenzene, 1,1-diphenylcycloalkane, polyphenylalkane, and polyphenylalkene, or ring assemblies such as 9,9-diphenylfluorene And monovalent groups of hydrocarbon compounds.
Examples of the heterocyclic group include monovalent groups such as carbazole, dibenzofuran, dibenzothiophene, oxadiazole, and thiadiazole.

The aryl group represented by Ar ₃ or Ar ₄ may have a substituent as shown below, for example.
(1) Halogen atom, cyano group, nitro group and the like.
(2) Alkyl groups, preferably C ₁ -C _12, especially C ₁ -C ₈ , more preferably C ₁ -C ₄ linear or branched alkyl groups, and these alkyl groups further contain fluorine atoms , a hydroxyl group, a cyano group, an alkoxy group of C ₁ -C _4, a phenyl group or a halogen atom, which may have a phenyl group substituted by an alkoxy group C ₁ -C ₄ alkyl or C ₁ -C ₄ Good. Specifically, methyl group, ethyl group, n-butyl group, i-propyl group, t-butyl group, s-butyl group, n-propyl group, trifluoromethyl group, 2-hydroxyethyl group, 2-ethoxyethyl Group, 2-cyanoethyl group, 2-methoxyethyl group, benzyl group, 4-chlorobenzyl group, 4-methylbenzyl group, 4-phenylbenzyl group and the like.
(3) An alkoxy group (—OR ₂ ), and R ₂ represents the alkyl group defined in (2). Specifically, methoxy group, ethoxy group, n-propoxy group, i-propoxy group, t-butoxy group, n-butoxy group, s-butoxy group, i-butoxy group, 2-hydroxyethoxy group, benzyloxy group And a trifluoromethoxy group.

(4) An aryloxy group, and examples of the aryl group include a phenyl group and a naphthyl group. It may contain an alkoxy group having C ₁ -C _4, alkyl group, or a halogen atom C ₁ -C ₄ as a substituent. Specific examples include a phenoxy group, a 1-naphthyloxy group, a 2-naphthyloxy group, a 4-methoxyphenoxy group, and a 4-methylphenoxy group.
(5) Alkyl mercapto group or aryl mercapto group, and specific examples include methylthio group, ethylthio group, phenylthio group, p-methylphenylthio group and the like.

（式中、Ｒ₃及びＲ₄は各々独立に水素原子、前記（２）で定義したアルキル基、またはアリール基を表わす。アリール基としては、例えばフェニル基、ビフェニル基又はナフチル基が挙げられ、これらはＣ₁〜Ｃ₄のアルコキシ基、Ｃ₁〜Ｃ₄のアルキル基またはハロゲン原子を置換基として含有してもよい。Ｒ₃及びＲ₄は共同で環を形成してもよい。）
具体的には、アミノ基、ジエチルアミノ基、Ｎ−メチル−Ｎ−フェニルアミノ基、Ｎ，Ｎ−ジフェニルアミノ基、Ｎ，Ｎ−ジ（トリール）アミノ基、ジベンジルアミノ基、ピペリジノ基、モルホリノ基、ピロリジノ基等が挙げられる。 (6)

(In the formula, R ₃ and R ₄ each independently represents a hydrogen atom, an alkyl group defined in (2) above, or an aryl group. Examples of the aryl group include a phenyl group, a biphenyl group, and a naphthyl group. these C ₁ -C ₄ alkoxy groups, C ₁ -C good .R ₃ and R ₄ may contain as alkyl group or a halogen atom substituents ₄ may be linked to form a ring.)
Specifically, amino group, diethylamino group, N-methyl-N-phenylamino group, N, N-diphenylamino group, N, N-di (tolyl) amino group, dibenzylamino group, piperidino group, morpholino group And pyrrolidino group.

(7) An alkylenedioxy group or an alkylenedithio group such as a methylenedioxy group or a methylenedithio group.
(8) A substituted or unsubstituted styryl group, a substituted or unsubstituted β-phenylstyryl group, a diphenylaminophenyl group, a ditolylaminophenyl group, and the like.

The arylene group represented by Ar ₁ or Ar ₂ is a divalent group derived from the aryl group represented by Ar ₃ or Ar ₄ .
X represents a single bond, a substituted or unsubstituted alkylene group, a substituted or unsubstituted cycloalkylene group, a substituted or unsubstituted alkylene ether group, an oxygen atom, a sulfur atom, or a vinylene group.
The substituted or unsubstituted alkylene group is a C _{1 to} C ₁₂ , preferably C _{1 to} C ₈ , more preferably a C _{1 to} C ₄ linear or branched alkylene group, and these alkylene groups include a fluorine atom, a hydroxyl group, a cyano group, an alkoxy group of C ₁ -C _4, a phenyl group or a halogen atom, a phenyl group substituted with an alkyl group or a C ₁ -C ₄ alkoxy group C ₁ -C ₄ It may be. Specifically, methylene group, ethylene group, n-butylene group, i-propylene group, t-butylene group, s-butylene group, n-propylene group, trifluoromethylene group, 2-hydroxyethylene group, 2-ethoxyethylene Group, 2-cyanoethylene group, 2-methoxyethylene group, benzylidene group, phenylethylene group, 4-chlorophenylethylene group, 4-methylphenylethylene group, 4-biphenylethylene group and the like.

The substituted or unsubstituted cycloalkylene group is a C _{5 to} C ₇ cyclic alkylene group, and these cyclic alkylene groups include a fluorine atom, a hydroxyl group, a C _{1 to} C ₄ alkyl group, and a C _{1 to} C ₄ alkyl group. It may have an alkoxy group. Specific examples include a cyclohexylidene group, a cyclohexylene group, and a 3,3-dimethylcyclohexylidene group.
The substituted or unsubstituted alkylene ether group represents ethyleneoxy, propyleneoxy, ethylene glycol, propylene glycol, diethylene glycol, tetraethylene glycol, tripropylene glycol, alkylene ether group alkylene group is hydroxyl group, methyl group, ethyl group, etc. You may have the substituent of.

で表わされ、Ｒ₅は水素、アルキル基（前記（２）で定義されるアルキル基と同じ）、アリール基（前記Ａｒ₃、Ａｒ₄で表わされるアリール基と同じ）、ａは１または２、ｂは１〜３を表わす。 The vinylene group is

R ₅ is hydrogen, an alkyl group (same as the alkyl group defined in (2) above), an aryl group (same as the aryl group represented by Ar ₃ or Ar ₄ above), a is 1 or 2 , B represents 1-3.

Z represents a substituted or unsubstituted alkylene group, a substituted or unsubstituted alkylene ether divalent group, or an alkyleneoxycarbonyl divalent group.
Examples of the substituted or unsubstituted alkylene group include the same alkylene groups as those described above for X.
Examples of the substituted or unsubstituted alkylene ether divalent group include the alkylene ether divalent group of X.
Examples of the alkyleneoxycarbonyl divalent group include a caprolactone divalent modifying group.

（式中、ｏ、ｐ、ｑはそれぞれ０又は１の整数、Ｒａは水素原子、メチル基を表わし、Ｒｂ、Ｒｃは水素原子以外の置換基で炭素数１〜６のアルキル基を表わし、複数の場合は異なっても良い。ｓ、ｔは０〜３の整数を表わす。Ｚａは単結合、メチレン基、エチレン基、

を表わす。）
上記一般式で表わされる化合物としては、Ｒｂ、Ｒｃの置換基として、特にメチル基、エチル基である化合物が好ましい。 Further, the radically polymerizable compound having a monofunctional charge transporting structure of the present invention is more preferably a compound having the structure of the following general formula (3).

(Wherein, o, p and q are each an integer of 0 or 1, Ra represents a hydrogen atom or a methyl group, Rb and Rc represent a substituent other than a hydrogen atom and an alkyl group having 1 to 6 carbon atoms, And s and t each represents an integer of 0 to 3. Za is a single bond, a methylene group, an ethylene group,

Represents. )
As the compound represented by the above general formula, a compound having a methyl group or an ethyl group as a substituent for Rb and Rc is particularly preferable.

  The radical polymerizable compound having a monofunctional charge transporting structure represented by the above general formulas (1) and (2), particularly (3) used in the present invention is polymerized by releasing the carbon-carbon double bond on both sides. Therefore, in the polymer that does not become a terminal structure, is incorporated in the chain polymer, and is crosslinked by polymerization with a tri- or higher functional radical polymerizable monomer, it exists in the main chain of the polymer, and Present in the main chain-cross-linked chain (this cross-linked chain has an intermolecular cross-linked chain between one polymer and another polymer, and a main chain folded in one polymer. There is an intramolecular cross-linked chain that crosslinks the site and another site derived from the polymerized monomer at a position away from this in the main chain), but even if it exists in the main chain, Even if present in the triarylamine structure suspended from the chain moiety, It has at least three aryl groups arranged in the radial direction from and is bulky, but it is not directly bonded to the chain part and is suspended from the chain part via a carbonyl group etc. Since these triarylamine structures can be arranged adjacent to each other in the polymer, there is little structural distortion in the molecule, and the surface of the electrophotographic photosensitive member is also fixed. In the case of a layer, it is presumed that an intramolecular structure that is relatively free from interruption of the charge transport pathway can be adopted.

Specific examples of the radically polymerizable compound having a monofunctional charge transporting structure of the present invention are shown below, but are not limited to the compounds having these structures.

  In addition, the radical polymerizable compound having a monofunctional charge transport structure used in the present invention is important for imparting the charge transport performance of the protective layer, and this component is preferably 20 to 80% by weight, preferably Is 30 to 70% by weight. If this component is less than 20% by weight, the charge transport performance of the protective layer cannot be maintained sufficiently, and repeated use tends to cause deterioration of electrical characteristics such as a decrease in sensitivity and an increase in residual potential. On the other hand, if it exceeds 80% by weight, the content of the trifunctional monomer having no charge transporting structure is lowered, and the crosslink density is lowered, so that high wear resistance tends to be hardly exhibited. The electrical characteristics and abrasion resistance required vary depending on the process used, and the thickness of the protective layer of the photoreceptor of the present invention varies accordingly. A weight percent range is most preferred.

  The protective layer constituting the electrophotographic photoreceptor of the present invention is obtained by curing at least a trifunctional or higher functional radical polymerizable monomer having no charge transport structure and a radical polymerizable compound having a monofunctional charge transport structure. In addition to this, monofunctional and bifunctional radically polymerizable monomers, functional monomers, and radical polymerization for the purpose of imparting functions such as viscosity adjustment during coating, stress relaxation of the protective layer, lower surface energy and friction coefficient reduction, etc. Can be used in combination. Known radical polymerizable monomers and oligomers can be used.

  Examples of the monofunctional radically polymerizable monomer include 2-ethylhexyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, tetrahydrofurfuryl acrylate, 2-ethylhexyl carbitol acrylate, 3-methoxybutyl acrylate, benzyl acrylate, Examples include cyclohexyl acrylate, isoamyl acrylate, isobutyl acrylate, methoxytriethylene glycol acrylate, phenoxytetraethylene glycol acrylate, cetyl acrylate, isostearyl acrylate, stearyl acrylate, and styrene monomer.

  Examples of the bifunctional radical polymerizable monomer include 1,3-butanediol diacrylate, 1,4-butanediol diacrylate, 1,4-butanediol dimethacrylate, 1,6-hexanediol diacrylate, 1, Examples include 6-hexanediol dimethacrylate, diethylene glycol diacrylate, neopentyl glycol diacrylate, bisphenol A-EO modified diacrylate, bisphenol F-EO modified diacrylate, neopentyl glycol diacrylate, and the like.

  Examples of the functional monomer include those substituted with a fluorine atom such as octafluoropentyl acrylate, 2-perfluorooctylethyl acrylate, 2-perfluorooctylethyl methacrylate, 2-perfluoroisononylethyl acrylate, No. 60503, JP-B-6-45770, siloxane repeating units: 20-70 acryloyl polydimethylsiloxane ethyl, methacryloyl polydimethylsiloxane ethyl, acryloyl polydimethylsiloxane propyl, acryloyl polydimethylsiloxane butyl, diacryloyl polydimethylsiloxane Examples include vinyl monomers having a polysiloxane group such as diethyl, acrylates and methacrylates.

Examples of the radical polymerizable oligomer include epoxy acrylate, urethane acrylate, and polyester acrylate oligomers.
However, when a large amount of monofunctional and bifunctional radically polymerizable monomers and radically polymerizable oligomers are contained, the three-dimensional crosslink density of the crosslinkable protective layer is substantially lowered, resulting in a decrease in wear resistance. Therefore, the content of these monomers and oligomers is more preferably 50 parts by weight or less, preferably 30 parts by weight or less with respect to 100 parts by weight of the tri- or higher functional radical polymerizable monomer.

  Further, the protective layer of the present invention is obtained by curing at least a trifunctional or higher-functional radical polymerizable monomer having no charge transport structure and a radical polymerizable compound having a monofunctional charge transport structure. In order to advance this curing reaction efficiently, a polymerization initiator may be included in the protective layer coating solution.

  Examples of the thermal polymerization initiator include 2,5-dimethylhexane-2,5-dihydroperoxide, dicumyl peroxide, benzoyl peroxide, t-butylcumyl peroxide, 2,5-dimethyl-2,5-di ( Peroxybenzoyl) hexyne-3, di-t-butyl peroxide, t-butyl hydroperoxide, cumene hydroperoxide, lauroyl peroxide, 2,2-bis (4,4-di-t-butylperoxycyclohexyl) B) Peroxide-based initiators such as propane, azo-based compounds such as azobisisobutylnitrile, azobiscyclohexanecarbonitrile, methyl azobisisobutyrate, azobisisobutylamidine hydrochloride, 4,4′-azobis-4-cyanovaleric acid Initiators are mentioned.

Examples of the photopolymerization initiator include diethoxyacetophenone, 2,2-dimethoxy-1,2-diphenylethane-1-one, 1-hydroxy-cyclohexyl-phenyl-ketone, 4- (2-hydroxyethoxy) phenyl- (2 -Hydroxy-2-propyl) ketone, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) butanone-1, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 2- Acetophenone-based or ketal-based photopolymerization initiators such as methyl-2-morpholino (4-methylthiophenyl) propan-1-one, 1-phenyl-1,2-propanedione-2- (o-ethoxycarbonyl) oxime, Benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isobutyl ether Benzoin ether photopolymerization initiators such as benzoin isopropyl ether, benzophenone, 4-hydroxybenzophenone, methyl o-benzoylbenzoate, 2-benzoylnaphthalene, 4-benzoylbiphenyl, 4-benzoylphenyl ether, acrylated benzophenone, Benzophenone photopolymerization initiators such as 1,4-benzoylbenzene, thioxanthones such as 2-isopropylthioxanthone, 2-chlorothioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, 2,4-dichlorothioxanthone Examples of photopolymerization initiators and other photopolymerization initiators include ethyl anthraquinone, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, 2,4,6-trimethylbenzoic acid. Phenylethoxyphosphine oxide, bis (2,4,6-trimethylbenzoyl) phenylphosphine oxide, bis (2,4-dimethoxybenzoyl) -2,4,4-trimethylpentylphosphine oxide, methylphenylglyoxyester, 9,10 -Phenanthrene, an acridine type compound, a triazine type compound, an imidazole type compound is mentioned. Moreover, what has a photopolymerization acceleration effect can also be used individually or in combination with the said photoinitiator. Examples thereof include triethanolamine, methyldiethanolamine, ethyl 4-dimethylaminobenzoate, isoamyl 4-dimethylaminobenzoate, (2-dimethylamino) ethyl benzoate, 4,4′-dimethylaminobenzophenone, and the like.
These polymerization initiators may be used alone or in combination of two or more. The content of the polymerization initiator is 0.5 to 40 parts by weight, preferably 1 to 20 parts by weight with respect to 100 parts by weight of the total content having radical polymerizability.

  Furthermore, the coating liquid for forming a protective layer of the present invention may contain additives such as various plasticizers (for the purpose of stress relaxation and adhesion improvement), leveling agents, and low molecular charge transport materials having no radical reactivity. Can be contained. As these additives, known additives can be used, and as plasticizers, those used in general resins such as dibutyl phthalate and dioctyl phthalate can be used, and the amount used is the total solid content of the coating liquid. To 20 wt% or less, preferably 10 wt% or less. As leveling agents, silicone oils such as dimethyl silicone oil and methylphenyl silicone oil, polymers or oligomers having a perfluoroalkyl group in the side chain can be used, and the amount used is based on the total solid content of the coating liquid. 3% by weight or less is appropriate.

  The protective layer of the present invention comprises a coating solution containing at least a trifunctional or higher-functional radical polymerizable monomer having no charge transport structure and a radical polymerizable compound having a monofunctional charge transport structure as described above. Alternatively, it is formed by applying and curing on the charge transport layer. When the radically polymerizable monomer is a liquid, such a coating liquid can be applied by dissolving other components in the liquid, but if necessary, it is diluted with a solvent and applied. Solvents used at this time include alcohols such as methanol, ethanol, propanol and butanol, ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone, esters such as ethyl acetate and butyl acetate, tetrahydrofuran, dioxane and propyl ether. And ethers such as dichloromethane, dichloroethane, trichloroethane and chlorobenzene, aromatics such as benzene, toluene and xylene, cellosolves such as methyl cellosolve, ethyl cellosolve and cellosolve acetate. These solvents may be used alone or in combination of two or more. The dilution ratio with the solvent varies depending on the solubility of the composition, the coating method, and the target film thickness, and is arbitrary. The application can be performed by dip coating, spray coating, bead coating, ring coating, or the like.

In this invention, after apply | coating this protective layer coating liquid, energy is given from the outside and it hardens | cures, and forms a protective layer, but there exist a heat | fever, light, a radiation etc. as external energy used at this time. The heat energy is applied by heating from the coating surface side or the support side using a gas such as air or nitrogen, steam, various heat media, infrared rays or electromagnetic waves. The heating temperature is preferably 100 ° C. or higher and 170 ° C. or lower. If the heating temperature is lower than 100 ° C., the reaction rate is slow and the curing reaction tends not to be completed completely. When the temperature exceeds 170 ° C., the curing reaction proceeds non-uniformly, and large strains, a large number of unreacted residues, and reaction termination terminals are generated in the protective layer. In order to advance the curing reaction uniformly, it is also effective to complete the reaction by heating at a relatively low temperature of less than 100 ° C. and then heating to 100 ° C. or more. UV light source such as high-pressure mercury lamp or metal halide lamp, which has emission wavelength mainly in the ultraviolet region, can be used as light energy. Select visible light source according to the absorption wavelength of radical polymerizable substance and photopolymerization initiator. Is also possible. Irradiation light amount is 50 mW / cm ² or more, preferably 1000 mW / cm ² or less, it takes time for the curing reaction is less than 50 mW / cm ^2. If it is higher than 1000 mW / cm ^2, the progress of the reaction becomes non-uniform, and local flaws are generated on the surface of the protective layer, and many unreacted residues and reaction termination ends are generated. In addition, internal stress increases due to rapid crosslinking, which causes cracks and film peeling. Examples of radiation energy include those using electron beams. Among these energies, those using heat and light energy are useful because of the ease of reaction rate control and the simplicity of the apparatus.

  The film thickness of the protective layer of the present invention is preferably 1 μm or more and 10 μm or less, more preferably 2 μm or more and 8 μm or less. If it is thicker than 10 μm, cracks and film peeling are likely to occur as described above, and if it is 8 μm or less, the margin is further improved, so that the crosslink density can be increased, and material selection and curing that further increases wear resistance. Conditions can be set. On the other hand, the radical polymerization reaction is prone to oxygen inhibition, that is, the surface in contact with the air is not easily cross-linked or non-uniform due to the effect of radical trapping by oxygen. This effect appears prominently when the surface layer is less than 1 μm, and the protective layer having a thickness less than this thickness is likely to have a reduced wear resistance and uneven wear. In addition, when the protective layer is applied, the lower charge transport layer component is mixed. Particularly, when the coating thickness of the protective layer is thin, the mixed material spreads over the entire layer, thereby inhibiting the curing reaction and lowering the crosslinking density. For these reasons, the protective layer of the present invention has a good wear resistance and scratch resistance at a film thickness of 1 μm or more. The wear increases, and the density unevenness of the halftone image tends to occur due to the charging property and sensitivity fluctuation. Therefore, it is desirable that the thickness of the protective layer is 2 μm or more for a longer life and higher image quality.

  In the electrophotographic photosensitive member of the present invention, the outermost protective layer is insoluble in the organic solvent in the structure in which the charge blocking layer, the moire preventing layer, the photosensitive layer (charge generation layer, charge transport layer), and the protective layer are sequentially laminated. The case is characterized by achieving dramatic wear resistance and scratch resistance. As a method for testing the solubility in an organic solvent, a drop of an organic solvent having high solubility in a polymer substance, for example, tetrahydrofuran, dichloromethane, or the like, is dropped on the surface layer of the photoconductor, and the surface shape of the photoconductor is dried after natural drying. It can be determined by observing the change with a stereomicroscope. Highly soluble photoconductors have a phenomenon that the central part of the droplet becomes concave and the surroundings swell up, the charge transport material precipitates and becomes cloudy or cloudy due to crystallization, and the surface swells and then shrinks, causing wrinkles Changes such as the phenomenon to be seen. In contrast, an insoluble photoconductor does not exhibit the above-described phenomenon, and does not change at all as before dropping.

  In the configuration of the present invention, in order to make the protective layer insoluble in the organic solvent, (1) the composition of the protective layer coating solution, adjustment of the content ratio thereof, (2) the diluted solvent of the protective layer coating solution, Controlling solid content concentration, (3) selection of coating method of protective layer, (4) control of curing condition of protective layer, (5) poor solubility of charge transport layer under layer, etc. can be controlled. Important, but not achieved by a single factor.

  Examples of the composition of the protective layer coating liquid include radical polymerizable functional groups other than the above-described tri- or higher functional radical polymerizable monomers not having a charge transport structure and a radical polymerizable compound having a monofunctional charge transport structure. When a large amount of additives such as binder resins, antioxidants, and plasticizers that do not contain bismuth are included, the crosslinking density is reduced, and the cured product resulting from the reaction and phase separation of the above additives occur, and are soluble in organic solvents. The tendency to become is high. Specifically, it is important to suppress the total content to 20% by weight or less with respect to the total solid content of the coating liquid. Further, in order not to dilute the crosslinking density, the total content of monofunctional or bifunctional radical polymerizable monomers, reactive oligomers, and reactive polymers is 20% by weight or less based on the trifunctional radical polymerizable monomers. It is desirable. Further, when a large amount of a radical polymerizable compound having a bifunctional or higher functional charge transporting structure is contained, a bulky structure is fixed in the crosslinked structure by a plurality of bonds, so that distortion is likely to occur. It is easy to become an aggregate. This can cause solubility in organic solvents. Although different depending on the compound structure, the content of the radical polymerizable compound having a bifunctional or higher functional charge transporting structure is preferably 10% by weight or less based on the radical polymerizable compound having a monofunctional charge transporting structure.

  As for the diluting solvent of the protective layer coating solution, if a solvent with a slow evaporation rate is used, the remaining solvent may hinder the curing or increase the amount of the lower layer components mixed. Bring about a decline. For this reason, it tends to be soluble in organic solvents. Specifically, tetrahydrofuran, a mixed solvent of tetrahydrofuran and methanol, ethyl acetate, methyl ethyl ketone, ethyl cellosolve and the like are useful, but are selected according to the coating method. Moreover, regarding the solid content concentration, if it is too low for the same reason, it tends to be soluble in an organic solvent. Conversely, the upper limit concentration is constrained by the limitations of film thickness and coating solution viscosity. Specifically, it is desirable to use in the range of 10 to 50% by weight. As the coating method of the protective layer, for the same reason, the solvent content at the time of coating film formation, a method of reducing the contact time with the solvent is preferable, specifically, the spray coating method, the amount of coating liquid was regulated. A ring coat method is preferred. In addition, in order to suppress the amount of the lower layer component to be mixed, a polymer charge transport material is used as the charge transport layer, and it is insoluble in the protective layer coating solvent between the photosensitive layer (or charge transport layer) and the protective layer. It is also effective to provide an intermediate layer.

As the curing conditions for the protective layer, if the energy of heating or light irradiation is low, the curing is not completely completed and the solubility in the organic solvent is increased. On the other hand, when cured with very high energy, the curing reaction becomes non-uniform, and it tends to increase the number of uncrosslinked parts and radical stopping parts and to form an aggregate of minute cured products. For this reason, it may become soluble in an organic solvent. To insolubilize in an organic solvent, the heat curing conditions are preferably 100 to 170 ° C. and 10 minutes to 3 hours, and the curing conditions by UV light irradiation are 50 to 1000 mW / cm ² and 5 seconds to 5 minutes. In addition, it is desirable to control the temperature rise to 50 ° C. or less to suppress non-uniform curing reaction.

  Examples of the method for making the protective layer constituting the electrophotographic photosensitive member of the present invention insoluble in an organic solvent include, for example, an acrylate monomer having three acryloyloxy groups and one acryloyloxy group as a coating solution. When a triarylamine compound is used, the ratio of use is 7: 3 to 3: 7, and a polymerization initiator is added in an amount of 3 to 20% by weight based on the total amount of these acrylate compounds, and a solvent is added to the coating. Prepare a working solution. For example, in the case where the surface layer is formed by spray coating using a triarylamine donor as the charge transport material and polycarbonate as the binder resin in the charge transport layer that is the lower layer of the protective layer, the solvent of the coating solution As for, tetrahydrofuran, 2-butanone, ethyl acetate, etc. are preferable, and the usage-amount is 3 times amount-10 times amount with respect to the acrylate compound whole quantity.

Next, for example, the prepared coating solution is applied by spraying or the like onto a photoreceptor in which a charge blocking layer, a moire prevention layer, a charge generation layer, and the charge transport layer are sequentially laminated on a support such as an aluminum cylinder. . Then, it is naturally dried or dried at a relatively low temperature for a short time (25 to 80 ° C., 1 to 10 minutes) and cured by UV irradiation or heating.
For UV irradiation, uses a metal halide lamp, illuminance 50 mW / cm ² or more, 1000 mW / cm ² or less, preferably about 5 minutes 5 seconds as the time, the drum temperature is controlled so as not to exceed 50 ° C. .
In the case of thermosetting, the heating temperature is preferably 100 to 170 ° C. For example, when a blowing oven is used as a heating means and the heating temperature is set to 150 ° C, the heating time is 20 minutes to 3 hours.
After completion of curing, the photosensitive member of the present invention is obtained by further heating at 100 to 150 ° C. for 10 to 30 minutes to reduce the residual solvent.

  As described above, the use of a polymer charge transport material for the photosensitive layer (charge transport layer) or the provision of a protective layer on the surface of the photoreceptor increases the durability (wear resistance) of each photoreceptor. In addition, when used in a tandem type full-color image forming apparatus as described later, a new effect not found in the monochrome image forming apparatus is also produced.

In the present invention, in order to improve environmental resistance, in order to prevent a decrease in sensitivity and an increase in residual potential, in particular, in each layer such as a protective layer, a charge transport layer, a charge generation layer, a charge blocking layer, and a moire prevention layer. Antioxidants can be added.
(Phenolic compounds)
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-tert-butylphenol), 2,2'-methylene-bis- (4-ethyl-6-tert-butylphenol), 4, 4'-thiobis- (3-methyl-6-tert-butylphenol), 4,4'-butylidenebis- (3-methyl-6-tert-butylphenol), 1,1,3-tris- (2-methyl-4 -Hydroxy-5-t-butylphenyl) butane, 1,3,5-trimethyl-2,4,6-tris (3,5-di-t-butyl-4-hydroxybenzyl) benzene, tetrakis- [methylene- -(3 ', 5'-di-t-butyl-4'-hydroxyphenyl) propionate] methane, bis [3,3'-bis (4'-hydroxy-3'-t-butylphenyl) butyric acid] Crycol esters, tocopherols, etc.

(Paraphenylenediamines)
N-phenyl-N'-isopropyl-p-phenylenediamine, N, N'-di-sec-butyl-p-phenylenediamine, N-phenyl-N-sec-butyl-p-phenylenediamine, N, N'- Di-isopropyl-p-phenylenediamine, N, N′-dimethyl-N, N′-di-t-butyl-p-phenylenediamine and the like.
(Hydroquinones)
2,5-di-t-octylhydroquinone, 2,6-didodecylhydroquinone, 2-dodecylhydroquinone, 2-dodecyl-5-chlorohydroquinone, 2-t-octyl-5-methylhydroquinone, 2- (2-octadecenyl) ) -5-methylhydroquinone and the like.

(Organic sulfur compounds)
Dilauryl-3,3′-thiodipropionate, distearyl-3,3′-thiodipropionate, ditetradecyl-3,3′-thiodipropionate, and the like.
(Organic phosphorus compounds)
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 in the present invention is 0.01 to 10% by weight based on the total weight of the layer to be added.

  In the case of a full-color image, various types of images are input, but on the contrary, a typical image may also be input. For example, the presence of a seal in a Japanese document or the like. Something like indicia is usually located towards the edge of the image area, and the colors used are also limited. In a state in which a random image is always written, image writing, development, and transfer are performed on the photoconductor in the image forming element on average. When many image formations are repeated or only a specific image forming element is used, the durability balance is lost. When a photoconductor having a low surface durability (physical / chemical / mechanical) is used in such a state, this difference becomes prominent and easily causes an image problem. On the other hand, when the photoconductor is made highly durable, the amount of such local change is small, and as a result, it becomes difficult to appear as a defect on the image, so that high durability is achieved and the stability of the output image is improved. This is very effective.

EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated, this invention is not restrict | limited by an Example. All parts are parts by weight.
(Synthesis Example 1)
A titanyl phthalocyanine crystal was synthesized according to Patent Document 48 and Example 1. 292 parts of 1,3-diiminoisoindoline and 1800 parts of sulfolane are mixed, and 204 parts of titanium tetrabutoxide are 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 completion of the reaction, the mixture was allowed to cool, and then the precipitate was filtered, washed with chloroform until the powder turned blue, then washed several times with methanol, further washed several times with hot water at 80 ° C., and dried. Crude titanyl phthalocyanine was obtained.
60 parts of the obtained crude titanyl phthalocyanine pigment washed with hot water were stirred and dissolved in 1000 parts of 96% sulfuric acid at 3 to 5 ° C. and filtered. The obtained sulfuric acid solution was added dropwise to 35000 parts of ice water with stirring, the precipitated crystals were filtered, and then washed with water until the washing solution became neutral to obtain an aqueous paste of titanyl phthalocyanine pigment.

  To this water paste, 1500 parts of tetrahydrofuran was added, and stirred vigorously (2000 rpm) with a homomixer (Kennis, MARKIIf model) at room temperature. Stirring was stopped and filtration under reduced pressure was immediately performed. The crystals obtained on the filter were washed with tetrahydrofuran to obtain 98 parts of a pigment wet cake. This was dried under reduced pressure (5 mmHg) at 70 ° C. for 2 days to obtain 78 parts of titanyl phthalocyanine crystals.

The obtained titanyl phthalocyanine powder was subjected to X-ray diffraction spectrum measurement under the following conditions. As a result, the Bragg angle 2θ with respect to Cu-Kα characteristic X-ray (wavelength 1.542 mm) had a maximum peak at 27.2 ± 0.2 °. In addition, it has major peaks at 9.4 ° ± 0.2 °, 9.6 ° ± 0.2 °, 24.0 ° ± 0.2 °, and a minimum angle of 7.3 ± 0.2 °. And a titanyl phthalocyanine powder having no peak between the peak at 7.3 ° and the peak at 9.4 ° and no peak at 26.3 ° was obtained. The result is 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

Part of the titanyl phthalocyanine crystal prepared in Synthesis Example 1 was diluted with tetrahydrofuran to a weight of approximately 1% by weight, and the surface was scooped with a copper net having a conductive treatment. (TEM, Hitachi: H-9000NAR) was observed at a magnification of 75000 times. The average particle size was determined as follows.
The TEM image observed as described above is taken as a TEM photograph, and 30 titanyl phthalocyanine particles (a shape close to a needle shape) projected are arbitrarily selected, and the size of each major axis is measured. The arithmetic average of the major diameters of the 30 individuals measured was determined as the average particle size.
The average particle size of the titanyl phthalocyanine crystal in Synthesis Example 1 obtained by the above method was 0.12 μm.

Next, a synthesis example of a compound having a monofunctional charge transporting structure used in a protective layer of a photoreceptor preparation example described later will be described.
(Synthesis example of a compound having a monofunctional charge transporting structure)
The compound having a monofunctional charge transport structure in the present invention is synthesized, for example, by the method described in Japanese Patent No. 3164426. An example of this is shown below.
(1) Synthesis of hydroxy group-substituted triarylamine compound (the following structural formula B) 113.85 parts (0.3 mol) of a methoxy group-substituted triarylamine compound (the following structural formula A) and 138 parts of sodium iodide (0. 92 mol) was added 240 parts of sulfolane and heated to 60 ° C. in a nitrogen stream. In this liquid, 99 parts (0.91 mol) of trimethylchlorosilane was added dropwise over 1 hour and stirred at a temperature of about 60 ° C. for 4 and a half hours to complete the reaction.
About 1500 parts of toluene was added to the reaction solution, cooled to room temperature, and washed repeatedly with water and an aqueous sodium carbonate solution.
Thereafter, the solvent was removed from the toluene solution and purified by column chromatography (adsorption medium: silica gel, developing solvent: toluene: ethyl acetate = 20: 1).
Cyclohexane was added to the obtained pale yellow oil to precipitate crystals.
In this way, 88.1 parts (yield = 80.4%) of white crystals of the following structural formula B were obtained.
Melting point: 64.0-66.0 ° C

(2) Synthesis example of triarylamino group-substituted acrylate compound (Exemplary Compound No. 54)
82.9 parts (0.227 mol) of the hydroxy group-substituted triarylamine compound (Structural Formula B) obtained in (1) above is dissolved in 400 parts of tetrahydrofuran, and an aqueous sodium hydroxide solution (NaOH: 12.2. 4 parts, water: 100 parts) was added dropwise.
The solution was cooled to 5 ° C., and 25.2 parts (0.272 mol) of acrylic acid chloride was added dropwise over 40 minutes. Then, it stirred at 5 degreeC for 3 hours, and reaction was complete | finished.
The reaction solution was poured into water and extracted with toluene. This extract was repeatedly washed with an aqueous sodium bicarbonate solution and water. Thereafter, the solvent was removed from the toluene solution and purified by column chromatography (adsorption medium: silica gel, developing solvent: toluene). N-Hexane was added to the obtained colorless oil to precipitate crystals.
In this way, Exemplified Compound No. 54.73 parts of white crystals (yield = 84.8%) were obtained.
Melting point: 117.5-119.0 ° C

(Dispersion Preparation Example 1)
The titanyl phthalocyanine crystal prepared in Synthesis Example 1 was dispersed according to the following composition under the following conditions to prepare a dispersion as a charge generation layer coating solution.
Titanyl phthalocyanine crystal 15 parts Polyvinyl butyral (manufactured by Sekisui Chemical Co., Ltd .: BX-1) 10 parts 2-butanone 280 parts A commercially available bead mill disperser using PSZ balls having a diameter of 0.5 mm, and 2-butanone and pigment dissolved with polyvinyl butyral All are charged and the rotor speed is 1200r. p. m. And dispersion was performed for 30 minutes to prepare a dispersion (referred to as dispersion 1).

ポリビニルブチラール（ＵＣＣ製：ＸＹＨＬ） １部
２−ブタノン １００部
シクロヘキサノン ２００部
ボールミルポットに、直径１０ｍｍのＰＳＺボールを用い、上記ポリビニルブチラール、２−ブタノン、シクロヘキサノン、およびジスアゾ顔料を全て投入し、５日間ボールミル分散を行った。ここに更に２−ブタノン１００部、シクロヘキサノン２００部を追加投入し、更に１日間ボールミル分散を行い、分散液を作製した（分散液２とする） (Dispersion preparation example 2)
Disazo pigment with the following structure: 5 parts

Polyvinyl butyral (UCC: XYHL) 1 part 2-butanone 100 parts cyclohexanone 200 parts Using a 10 mm diameter PSZ ball in a ball mill pot, all of the polyvinyl butyral, 2-butanone, cyclohexanone, and disazo pigment are added for 5 days. Ball mill dispersion was performed. Further, 100 parts of 2-butanone and 200 parts of cyclohexanone were further added thereto, and ball mill dispersion was further performed for 1 day to prepare a dispersion (referred to as dispersion 2).

(Photoreceptor Preparation Example 1)
Charge blocking layer coating solution, moire prevention layer coating solution, charge generation layer coating solution, charge transport layer coating solution and protective layer coating solution having the following composition are sequentially applied to an aluminum cylinder (JIS1050) having a diameter of 100 mm. Drying and forming a 1.0 μm charge blocking layer, a 3.5 μm moire prevention layer, a charge generation layer, a 23 μm charge transport layer, and a 5 μm protective layer to produce a laminated photoreceptor (Photoreceptor 1) ).
The film thickness of the charge generation layer was adjusted so that the transmittance of the charge generation layer at 780 nm was 25%. The transmittance of the charge generation layer is obtained by applying a charge generation layer coating solution of the following composition to an aluminum cylinder wrapped with a polyethylene terephthalate film under the same conditions as the production of the photoreceptor, and the polyethylene without the charge generation layer applied Using the terephthalate film as a comparative control, the transmittance at 780 nm was evaluated with a commercially available spectrophotometer (Shimadzu: UV-3100).

◎ Charge blocking layer coating solution N-methoxymethylated nylon (Lead City: Fine Resin FR-101) 4 parts Methanol 70 parts n-Butanol 30 parts ◎ Moire prevention layer coating solution Titanium oxide (CR-EL: Ishihara Sangyo Co., Ltd.) Manufactured, average particle size: 0.25 μm) 126 parts alkyd resin [Beckolite M6401-50-S (solid content 50%),
Dainippon Ink & Chemicals, Inc.] 33.6 parts Melamine resin [Super Becamine L-121-60 (solid content 60%),
Dainippon Ink & Chemicals, Inc.] 18.7 parts 2-butanone 100 parts In the above composition, the volume ratio of the inorganic pigment to the binder resin is 1.5 / 1.
The ratio of alkyd resin to melamine resin is a 6/4 weight ratio.

塩化メチレン ８０部 Charge generation layer coating solution Dispersion 1 prepared earlier was used.
◎ Charge transport layer coating solution Polycarbonate (TS2050: manufactured by Teijin Chemicals Ltd.) 10 parts Charge transport material of the following structural formula: 7 parts

80 parts of methylene chloride

光重合開始剤 １部
１−ヒドロキシ−シクロヘキシル−フェニル−ケトン
（イルガキュア１８４、チバ・スペシャルティ・ケミカルズ製）
テトラヒドロフラン １００部
保護層は、スプレー塗工してから２０分間自然乾燥した後、メタルハライドランプ：１６０Ｗ／ｃｍ、照射強度：５００ｍＷ／ｃｍ²、照射時間：６０秒の条件で光照射を行うことによって塗布膜を硬化させた。 ◎ Protective layer coating solution Trifunctional or higher functional radical polymerizable monomer having no charge transporting structure 10 parts {Trimethylolpropane triacrylate (KAYARAD TMPTA, Nippon Kayaku)
Molecular weight: 296, number of functional groups: trifunctional, molecular weight / number of functional groups = 99}
10 parts of radically polymerizable compound having a monofunctional charge transporting structure having the following structure (Exemplary Compound No. 54)

Photoinitiator 1 part 1-Hydroxy-cyclohexyl-phenyl-ketone (Irgacure 184, manufactured by Ciba Specialty Chemicals)
Tetrahydrofuran 100 parts The protective layer is spray-coated and air-dried for 20 minutes, and then applied by light irradiation under conditions of a metal halide lamp: 160 W / cm, irradiation intensity: 500 mW / cm ² , irradiation time: 60 seconds. The film was cured.

(Photoreceptor preparation example 2)
In Photoconductor Preparation Example 1, a photoconductor was prepared in the same manner as Photoconductor Preparation Example 1 except that no charge blocking layer was provided (referred to as Photoconductor 2).
(Photoreceptor Preparation Example 3)
In Photoconductor Preparation Example 1, a photoconductor was prepared in the same manner as Photoconductor Preparation Example 1 except that no moire prevention layer was provided (referred to as Photoconductor 3).
(Photosensitive member production example 4)
In Photoconductor Preparation Example 1, a photoconductor was prepared in the same manner as Photoconductor Preparation Example 1 except that the coating order of the charge blocking layer and the moire prevention layer was changed (referred to as Photoconductor 4).

(Photoreceptor Preparation Example 5)
In Photoconductor Preparation Example 1, a photoconductor was prepared in the same manner as Photoconductor Preparation Example 1 except that the thickness of the charge blocking layer was 0.1 μm (referred to as Photoconductor 5).
(Photosensitive member preparation example 6)
A photoconductor was prepared in the same manner as in Photoconductor Preparation Example 1 except that the charge blocking layer thickness was 0.3 μm in Photoconductor Preparation Example 1 (referred to as Photoconductor 6).
(Photoreceptor Preparation Example 7)
In Photoconductor Preparation Example 1, a photoconductor was prepared in the same manner as Photoconductor Preparation Example 1 except that the thickness of the charge blocking layer was 0.6 μm (referred to as Photoconductor 7).

(Photoreceptor Preparation Example 8)
A photoconductor was prepared in the same manner as in Photoconductor Preparation Example 1 except that the thickness of the charge blocking layer was 1.8 μm in Photoconductor Preparation Example 1 (referred to as Photoconductor 8).
(Photoreceptor Preparation Example 9)
A photoconductor was prepared in the same manner as in Photoconductor Preparation Example 1 except that the charge blocking layer thickness was 2.3 μm in Photoconductor Preparation Example 1 (referred to as Photoconductor 9).

(Photoreceptor Preparation Example 10)
In Photoconductor Preparation Example 1, a photoconductor was prepared in the same manner as in Photoconductor Preparation Example 1 except that the charge blocking layer coating solution was changed to one having the following composition (referred to as Photoconductor 10).
◎ Charge blocking layer coating solution Alcohol-soluble nylon (Toray: Amilan CM8000) 4 parts Methanol 70 parts n-Butanol 30 parts

(Photoreceptor Preparation Example 11)
In Photoconductor Preparation Example 1, a photoconductor was prepared in the same manner as Photoconductor Preparation Example 1 except that the charge blocking layer coating solution was changed to one having the following composition (referred to as Photoconductor 11).
Charge blocking layer coating solution Alkyd resin [Beckolite M6401-50-S (solid content 50%),
Dainippon Ink & Chemicals, Inc.] 33.6 parts Melamine resin [Super Becamine L-121-60 (solid content 60%),
Dainippon Ink & Chemicals, Inc.] 18.7 parts 2-butanone 400 parts

(Photoconductor Preparation Example 12)
In Photoconductor Preparation Example 1, a photoconductor was prepared in the same manner as Photoconductor Preparation Example 1 except that the moire preventing layer coating solution was changed to one having the following composition (referred to as Photoconductor 12).
◎ Moire prevention layer coating solution Titanium oxide (CR-EL: manufactured by Ishihara Sangyo Co., Ltd., average particle size: 0.25 μm) 168 parts Alkyd resin [Beckolite M6401-50-S (solid content 50%),
Dainippon Ink & Chemicals, Inc.] 33.6 parts Melamine resin [Super Becamine L-121-60 (solid content 60%),
Dai Nippon Ink Chemical Co., Ltd.] 18.7 parts 2-butanone 100 parts In the above composition, the volume ratio of the inorganic pigment to the binder resin is 2/1.
The ratio of alkyd resin to melamine resin is a 6/4 weight ratio.

(Photoreceptor Preparation Example 13)
In Photoconductor Preparation Example 1, a photoconductor was prepared in the same manner as Photoconductor Preparation Example 1 except that the moire preventing layer coating solution was changed to one having the following composition (referred to as Photoconductor 13).
◎ Moire prevention layer coating solution Titanium oxide (CR-EL: manufactured by Ishihara Sangyo Co., Ltd., average particle size: 0.25 μm) 252 parts Alkyd resin [Beckolite M6401-50-S (solid content 50%),
Dainippon Ink & Chemicals, Inc.] 33.6 parts Melamine resin [Super Becamine L-121-60 (solid content 60%),
Dai Nippon Ink Chemical Co., Ltd.] 18.7 parts 2-butanone 100 parts In the above composition, the volume ratio of the inorganic pigment to the binder resin is 3/1.
The ratio of alkyd resin to melamine resin is a 6/4 weight ratio.

(Photoreceptor Preparation Example 14)
In Photoconductor Preparation Example 1, a photoconductor was prepared in the same manner as Photoconductor Preparation Example 1 except that the moire preventing layer coating solution was changed to one having the following composition (referred to as Photoconductor 14).
◎ Moire prevention layer coating solution Titanium oxide (CR-EL: manufactured by Ishihara Sangyo Co., Ltd., average particle size: 0.25 μm) 84 parts Alkyd resin [Beckolite M6401-50-S (solid content 50%),
Dainippon Ink & Chemicals, Inc.] 33.6 parts Melamine resin [Super Becamine L-121-60 (solid content 60%),
Dai Nippon Ink Chemical Co., Ltd.] 18.7 parts 2-butanone 100 parts In the above composition, the volume ratio of the inorganic pigment to the binder resin is 1/1.
The ratio of alkyd resin to melamine resin is a 6/4 weight ratio.

(Photoreceptor Preparation Example 15)
In Photoconductor Preparation Example 1, a photoconductor was prepared in the same manner as Photoconductor Preparation Example 1 except that the moire preventing layer coating solution was changed to one having the following composition (referred to as Photoconductor 15).
◎ Moire prevention layer coating solution Titanium oxide (CR-EL: manufactured by Ishihara Sangyo Co., Ltd., average particle size: 0.25 μm) 42 parts Alkyd resin [Beckolite M6401-50-S (solid content 50%),
Dainippon Ink & Chemicals, Inc.] 33.6 parts Melamine resin [Super Becamine L-121-60 (solid content 60%),
Dai Nippon Ink Chemical Co., Ltd.] 18.7 parts 2-butanone 100 parts In the above composition, the volume ratio of the inorganic pigment to the binder resin is 0.5 / 1.
The ratio of alkyd resin to melamine resin is a 6/4 weight ratio.

(Photoreceptor Production Example 16)
In Photoconductor Preparation Example 1, a photoconductor was prepared in the same manner as Photoconductor Preparation Example 1 except that the moire preventing layer coating solution was changed to one having the following composition (referred to as Photoconductor 16).
◎ Moire prevention layer coating solution Titanium oxide (CR-EL: manufactured by Ishihara Sangyo Co., Ltd., average particle size: 0.25 μm) 336 parts Alkyd resin [Beckolite M6401-50-S (solid content 50%),
Dainippon Ink & Chemicals, Inc.] 33.6 parts Melamine resin [Super Becamine L-121-60 (solid content 60%),
Dai Nippon Ink Chemical Co., Ltd.] 18.7 parts 2-butanone 100 parts In the above composition, the volume ratio of the inorganic pigment to the binder resin is 4/1.
The ratio of alkyd resin to melamine resin is a 6/4 weight ratio.

(Photoreceptor Preparation Example 17)
In Photoconductor Preparation Example 1, a photoconductor was prepared in the same manner as Photoconductor Preparation Example 1 except that the moire preventing layer coating solution was changed to one having the following composition (referred to as Photoconductor 17).
◎ Moire prevention layer coating solution Titanium oxide (CR-EL: Ishihara Sangyo Co., Ltd., average particle size: 0.25 μm) 126 parts N-methoxymethylated nylon (Lead City: Fine Resin FR-101)
27.5 parts Tartaric acid (curing catalyst) 1 part 2-butanone 100 parts In the above composition, the volume ratio of the inorganic pigment to the binder resin is 1.5 / 1.

(Photoreceptor Preparation Example 18)
In Photoconductor Preparation Example 1, a photoconductor was prepared in the same manner as Photoconductor Preparation Example 1 except that the moire preventing layer coating solution was changed to one having the following composition (referred to as Photoconductor 18).
◎ Moire prevention layer coating solution Titanium oxide (CR-EL: manufactured by Ishihara Sangyo Co., Ltd., average particle size: 0.25 μm) 126 parts Alkyd resin [Beckolite M6401-50-S (solid content 50%),
Dainippon Ink and Chemicals Co., Ltd.] 22.4 parts Melamine resin [Super Becamine L-121-60 (solid content 60%),
Dai Nippon Ink Chemical Co., Ltd.] 28 parts 2-butanone 100 parts In the above composition, the volume ratio of the inorganic pigment to the binder resin is 1.5 / 1.
The ratio of alkyd resin to melamine resin is 4/6 weight ratio.

(Photoreceptor Preparation Example 19)
In Photoconductor Preparation Example 1, a photoconductor was prepared in the same manner as in Photoconductor Preparation Example 1 except that the moire preventing layer coating solution was changed to one having the following composition (referred to as Photoconductor 19).
◎ Moire prevention layer coating solution Titanium oxide (CR-EL: manufactured by Ishihara Sangyo Co., Ltd., average particle size: 0.25 μm) 126 parts Alkyd resin [Beckolite M6401-50-S (solid content 50%),
Dainippon Ink & Chemicals, Inc.] 28 parts Melamine resin [Super Becamine L-121-60 (solid content 60%),
Dainippon Ink & Chemicals, Inc.] 23.3 parts 2-butanone 100 parts In the above composition, the volume ratio of the inorganic pigment to the binder resin is 1.5 / 1.
The ratio of alkyd resin to melamine resin is 5/5 weight ratio.

(Photoreceptor Preparation Example 20)
In Photoconductor Preparation Example 1, a photoconductor was prepared in the same manner as Photoconductor Preparation Example 1 except that the moire preventing layer coating solution was changed to one having the following composition (referred to as Photoconductor 20).
◎ Moire prevention layer coating solution Titanium oxide (CR-EL: manufactured by Ishihara Sangyo Co., Ltd., average particle size: 0.25 μm) 126 parts Alkyd resin [Beckolite M6401-50-S (solid content 50%),
Dainippon Ink & Chemicals, Inc.] 39.2 parts Melamine resin [Super Becamine L-121-60 (solid content 60%),
Dai Nippon Ink Chemical Co., Ltd.] 14 parts 2-butanone 100 parts In the above composition, the volume ratio of the inorganic pigment to the binder resin is 1.5 / 1.
The ratio of alkyd resin to melamine resin is a 7/3 weight ratio.

(Photoconductor Preparation Example 21)
In Photoconductor Preparation Example 1, a photoconductor was prepared in the same manner as Photoconductor Preparation Example 1 except that the moire preventing layer coating solution was changed to one having the following composition (referred to as Photoconductor 21).
◎ Moire prevention layer coating solution Titanium oxide (CR-EL: manufactured by Ishihara Sangyo Co., Ltd., average particle size: 0.25 μm) 126 parts Alkyd resin [Beckolite M6401-50-S (solid content 50%),
Dainippon Ink & Chemicals, Inc.] 44.8 parts Melamine resin [Super Becamine L-121-60 (solid content 60%),
Dai Nippon Ink Chemical Co., Ltd.] 9.3 parts 2-butanone 100 parts In the above composition, the volume ratio of the inorganic pigment and the binder resin is 1.5 / 1.
The ratio of alkyd resin to melamine resin is 8/2 weight ratio.

(Photoconductor Preparation Example 22)
In Photoconductor Preparation Example 1, a photoconductor was prepared in the same manner as Photoconductor Preparation Example 1 except that the moire preventing layer coating solution was changed to one having the following composition (referred to as Photoconductor 22).
◎ Moire prevention layer coating solution Titanium oxide (CR-EL: manufactured by Ishihara Sangyo Co., Ltd., average particle size: 0.25 μm) 126 parts Alkyd resin [Beckolite M6401-50-S (solid content 50%),
Dainippon Ink & Chemicals, Inc.] 50.4 parts Melamine resin [Super Becamine L-121-60 (solid content 60%),
Dai Nippon Ink Chemical Co., Ltd.] 4.7 parts 2-butanone 100 parts In the above composition, the volume ratio of the inorganic pigment and the binder resin is 1.5 / 1.
The ratio of alkyd resin to melamine resin is 9/1 weight ratio.

(Photoconductor Preparation Example 23)
In Photoconductor Preparation Example 1, a photoconductor was prepared in the same manner as Photoconductor Preparation Example 1 except that the moire prevention layer coating solution was changed to one having the following composition (referred to as Photoconductor 23).
◎ Moire prevention layer coating solution Zinc oxide (SAZEX 4000: manufactured by Sakai Chemical) 165 parts Alkyd resin [Beckolite M6401-50-S (solid content 50%),
Dainippon Ink & Chemicals, Inc.] 33.6 parts Melamine resin [Super Becamine L-121-60 (solid content 60%),
Dai Nippon Ink Chemical Co., Ltd.] 18.7 parts 2-butanone 120 parts In the above composition, the volume ratio of the inorganic pigment to the binder resin is 1.5 / 1.
The ratio of alkyd resin to melamine resin is a 6/4 weight ratio.

(Photoconductor Preparation Example 24)
In Photoconductor Preparation Example 1, a photoconductor was prepared in the same manner as Photoconductor Preparation Example 1 except that the moire preventing layer coating solution was changed to one having the following composition (referred to as Photoconductor 24).
◎ Moire prevention layer coating solution Titanium oxide (CR-EL: manufactured by Ishihara Sangyo Co., Ltd., average particle size: 0.25 μm) 63 parts Titanium oxide (PT-401M: manufactured by Ishihara Sangyo Co., Ltd., average particle size: 0.07 μm) 63 Part Alkyd resin [Beckolite M6401-50-S (solid content 50%),
Dainippon Ink & Chemicals, Inc.] 33.6 parts Melamine resin [Super Becamine L-121-60 (solid content 60%),
Dainippon Ink & Chemicals, Inc.] 18.7 parts 2-butanone 100 parts In the above composition, the volume ratio of the inorganic pigment to the binder resin is 1.5 / 1.
The ratio of alkyd resin to melamine resin is a 6/4 weight ratio.
The ratio of the average particle diameter of titanium oxide (D2 / D1) is 0.28, and the mixing ratio (T2 / (T1 + T2)) of both is 0.5.

(Photoconductor Preparation Example 25)
A photoconductor was prepared in the same manner as in Photoconductor Preparation Example 1 except that the moire-preventing layer coating solution was changed to one having the following composition in Photoconductor Preparation Example 1 (referred to as Photoconductor 25).
◎ Moire prevention layer coating solution Titanium oxide (CR-EL: manufactured by Ishihara Sangyo Co., Ltd., average particle size: 0.25 μm)
113.4 parts Titanium oxide (PT-401M: manufactured by Ishihara Sangyo Co., Ltd., average particle size: 0.07 μm)
12.6 parts Alkyd resin [Beckolite M6401-50-S (solid content 50%),
Dainippon Ink & Chemicals, Inc.] 33.6 parts Melamine resin [Super Becamine L-121-60 (solid content 60%),
Dainippon Ink & Chemicals, Inc.] 18.7 parts 2-butanone 100 parts In the above composition, the volume ratio of the inorganic pigment to the binder resin is 1.5 / 1.
The ratio of alkyd resin to melamine resin is a 6/4 weight ratio.
The ratio of the average particle diameter of titanium oxide (D2 / D1) is 0.28, and the mixing ratio (T2 / (T1 + T2)) of both is 0.1.

(Photoconductor Preparation Example 26)
In Photoconductor Preparation Example 1, a photoconductor was prepared in the same manner as Photoconductor Preparation Example 1 except that the moire preventing layer coating solution was changed to one having the following composition (referred to as Photoconductor 26).
◎ Moire prevention layer coating solution Titanium oxide (CR-EL: Ishihara Sangyo Co., Ltd., average particle size: 0.25 μm) 12.6 parts Titanium oxide (PT-401M: Ishihara Sangyo Co., Ltd., average particle size: 0.07 μm) )
113.4 parts alkyd resin [Beckolite M6401-50-S (solid content 50%),
Dainippon Ink & Chemicals, Inc.] 33.6 parts Melamine resin [Super Becamine L-121-60 (solid content 60%),
Dainippon Ink & Chemicals, Inc.] 18.7 parts 2-butanone 100 parts In the above composition, the volume ratio of the inorganic pigment to the binder resin is 1.5 / 1.
The ratio of alkyd resin to melamine resin is a 6/4 weight ratio.
The ratio of the average particle diameter of titanium oxide (D2 / D1) is 0.28, and the mixing ratio (T2 / (T1 + T2)) of both is 0.9.

(Photoconductor Preparation Example 27)
A photoconductor was prepared in the same manner as in Photoconductor Preparation Example 1 except that the moire-preventing layer coating solution was changed to one having the following composition in Photoconductor Preparation Example 1 (referred to as Photoconductor 27).
◎ Moire prevention layer coating solution Titanium oxide (CR-EL: manufactured by Ishihara Sangyo Co., Ltd., average particle size: 0.25 μm) 63 parts Titanium oxide (TTO-F1: manufactured by Ishihara Sangyo Co., Ltd., average particle size: 0.04 μm) 63 Part Alkyd resin [Beckolite M6401-50-S (solid content 50%),
Dainippon Ink & Chemicals, Inc.] 33.6 parts Melamine resin [Super Becamine L-121-60 (solid content 60%),
Dainippon Ink & Chemicals, Inc.] 18.7 parts 2-butanone 100 parts In the above composition, the volume ratio of the inorganic pigment to the binder resin is 1.5 / 1.
The ratio of alkyd resin to melamine resin is a 6/4 weight ratio.
The ratio of the average particle diameter of titanium oxide (D2 / D1) is 0.16, and the mixing ratio (T2 / (T1 + T2)) of both is 0.5.

(Photoreceptor Preparation Example 28)
In Photoconductor Preparation Example 1, a photoconductor was prepared in the same manner as Photoconductor Preparation Example 1 except that the moire preventing layer coating solution was changed to one having the following composition (referred to as Photoconductor 28).
◎ Moire prevention layer coating solution Titanium oxide (CR-EL: manufactured by Ishihara Sangyo Co., Ltd., average particle size: 0.25 μm) 63 parts Titanium oxide (A-100: manufactured by Ishihara Sangyo Co., Ltd., average particle size: 0.15 μm) 63 Part Alkyd resin [Beckolite M6401-50-S (solid content 50%),
Dainippon Ink & Chemicals, Inc.] 33.6 parts Melamine resin [Super Becamine L-121-60 (solid content 60%),
Dainippon Ink & Chemicals, Inc.] 18.7 parts 2-butanone 100 parts In the above composition, the volume ratio of the inorganic pigment to the binder resin is 1.5 / 1.
The ratio of alkyd resin to melamine resin is a 6/4 weight ratio.
The ratio of the average particle diameter of titanium oxide (D2 / D1) is 0.6, and the mixing ratio (T2 / (T1 + T2)) of both is 0.5.

下記構造の添加剤 ０．５部

塩化メチレン １００部 (Photoconductor Preparation Example 29)
A photoconductor was prepared in the same manner as in Photoconductor Preparation Example 1 except that the charge transport layer coating solution in Photoconductor Preparation Example 1 was changed to one having the following composition (referred to as Photoconductor 29).
Charge transport layer coating solution Polymer charge transport material having the following composition (weight average molecular weight: about 135,000) 10 parts

0.5 parts of additive with the following structure

100 parts methylene chloride

アルミナ微粒子（比抵抗：２．５×１０^１２Ω・ｃｍ、平均一次粒径：０．４μｍ）
４部
シクロヘキサノン ５００部
テトラヒドロフラン １５０部 (Photoreceptor Preparation Example 30)
A photoconductor was prepared in the same manner as in Photoconductor Preparation Example 1 except that the protective layer coating solution in Photoconductor Preparation Example 1 was changed to one having the following composition, and was coated and dried (no ultraviolet irradiation was performed). 30).
◎ Protective layer coating solution Polycarbonate (TS2050: manufactured by Teijin Chemicals Ltd., viscosity average molecular weight: 50,000)
10 parts Charge transport material of the following structural formula 7 parts

Alumina fine particles (specific resistance: 2.5 × 10 ¹² Ω · cm, average primary particle size: 0.4 μm)
4 parts Cyclohexanone 500 parts Tetrahydrofuran 150 parts

アルミナ微粒子（比抵抗：２．５×１０^１２Ω・ｃｍ、平均一次粒径：０．４μｍ）
４部
シクロヘキサノン ５００部
テトラヒドロフラン １５０部 (Photoreceptor Preparation Example 31)
A photoconductor was prepared in the same manner as in Photoconductor Preparation Example 30 except that the protective layer coating solution in Photoconductor Preparation Example 30 was changed to the following (hereinafter referred to as Photoconductor 31).
◎ Protective layer coating solution Polymer charge transport material having the following composition (weight average molecular weight: about 135,000) 10 parts

Alumina fine particles (specific resistance: 2.5 × 10 ¹² Ω · cm, average primary particle size: 0.4 μm)
4 parts Cyclohexanone 500 parts Tetrahydrofuran 150 parts

酸化防止剤（サノール ＬＳ２６２６：三共化学社製） １部
硬化剤（ジブチル錫アセテート） １部
２−プロパノール ２００部 (Photoconductor Preparation Example 32)
A photoconductor was prepared in the same manner as in Photoconductor Preparation Example 30 except that the protective layer coating solution in Photoconductor Preparation Example 30 was changed to the following (hereinafter referred to as Photoconductor 32).
◎ Protective layer coating solution Methyltrimethoxysilane 100 parts 3% acetic acid 20 parts Charge transporting compound with the following structure 35 parts

Antioxidant (Sanol LS2626: Sankyo Chemical Co., Ltd.) 1 part Curing agent (dibutyltin acetate) 1 part 2-propanol 200 parts

(Photoconductor Preparation Example 33)
In Photoconductor Preparation Example 1, all the examples except for changing the trifunctional or higher functional radical polymerizable monomer having no charge transporting structure contained in the protective layer coating solution to the following radical polymerizable monomer In the same manner as in Example 1, an electrophotographic photoreceptor was prepared (referred to as photoreceptor 33).
10 parts of tri- or higher functional radical polymerizable monomer having no charge transport structure (pentaerythritol tetraacrylate (SR-295, manufactured by Kayaku Sartomer)
(Molecular weight: 352, number of functional groups: tetrafunctional, molecular weight / number of functional groups = 88)

(Photoconductor Preparation Example 34)
A trifunctional or higher functional radical polymerizable monomer having no charge transporting structure contained in the protective layer coating solution of Photosensitive Member Preparation Example 1 is converted into the following bifunctional radical polymerizable monomer 10 having no charge transporting structure: An electrophotographic photoreceptor was produced in the same manner as in Photoreceptor Production Example 1 except that the parts were changed (referred to as photoreceptor 34).
10 parts of a bifunctional radically polymerizable monomer having no charge transporting structure (1,6-hexanediol diacrylate (manufactured by Wako Pure Chemical Industries, Ltd.))
Molecular weight: 226, number of functional groups: bifunctional, molecular weight / number of functional groups = 113)

(Photoconductor Preparation Example 35)
In Photoreceptor Preparation Example 1, all the examples except for changing the trifunctional or higher functional radical polymerizable monomer having no charge transporting structure contained in the protective layer coating solution to the following radical polymerizable monomer In the same manner as in Example 1, an electrophotographic photoreceptor was produced (referred to as photoreceptor 35).
Trifunctional or higher functional radical polymerizable monomer having no charge transport structure 10 parts (Caprolactone-modified dipentaerythritol hexaacrylate (KAYARAD DPCA-120, manufactured by Nippon Kayaku)
(Molecular weight: 1947, number of functional groups: 6 functions, molecular weight / number of functional groups = 325)

(Photoconductor Preparation Example 36)
10 parts of a radically polymerizable compound having a monofunctional charge transporting structure represented by the following structural formula contained in the protective layer coating solution of Preparation Example 1 of the photoreceptor An electrophotographic photosensitive member was prepared in the same manner as in Photoconductor Preparation Example 1 (except for Photoconductor 36), except that

光重合開始剤 １部
１−ヒドロキシ−シクロヘキシル−フェニル−ケトン
（イルガキュア１８４、チバ・スペシャルティ・ケミカルズ製）
テトラヒドロフラン １００部 (Photoreceptor Preparation Example 37)
In Photoconductor Preparation Example 1, an electrophotographic photoconductor was prepared in the same manner as Photoconductor Preparation Example 1 except that the protective layer coating solution was changed to the following composition (referred to as Photoconductor 37).
◎ Protective layer coating liquid Trifunctional or higher functional radical polymerizable monomer having no charge transport structure 6 parts {Trimethylolpropane triacrylate (KAYARAD TMPTA, Nippon Kayaku)
Molecular weight: 296, number of functional groups: trifunctional, molecular weight / number of functional groups = 99}
14 parts of radically polymerizable compound having a monofunctional charge transporting structure having the following structure (Exemplary Compound No. 54)

Photoinitiator 1 part 1-Hydroxy-cyclohexyl-phenyl-ketone (Irgacure 184, manufactured by Ciba Specialty Chemicals)
Tetrahydrofuran 100 parts

光重合開始剤 １部
１−ヒドロキシ−シクロヘキシル−フェニル−ケトン
（イルガキュア１８４、チバ・スペシャルティ・ケミカルズ製）
テトラヒドロフラン １００部 (Photoconductor Preparation Example 38)
In Photoconductor Preparation Example 1, an electrophotographic photoconductor was prepared in the same manner as Photoconductor Preparation Example 1 except that the protective layer coating solution was changed to the following composition (referred to as Photoconductor 38).
◎ Protective layer coating solution Trifunctional or higher functional radical polymerizable monomer having no charge transport structure 14 parts {Trimethylolpropane triacrylate (KAYARAD TMPTA, Nippon Kayaku)
Molecular weight: 296, number of functional groups: trifunctional, molecular weight / number of functional groups = 99}
6 parts of a radical polymerizable compound having a monofunctional charge transport structure having the following structure (Exemplary Compound No. 54)

Photoinitiator 1 part 1-Hydroxy-cyclohexyl-phenyl-ketone (Irgacure 184, manufactured by Ciba Specialty Chemicals)
Tetrahydrofuran 100 parts

光重合開始剤 １部
１−ヒドロキシ−シクロヘキシル−フェニル−ケトン
（イルガキュア１８４、チバ・スペシャルティ・ケミカルズ製）
テトラヒドロフラン １００部 (Photoconductor Preparation Example 39)
In Photoconductor Preparation Example 1, an electrophotographic photoconductor was prepared in the same manner as Photoconductor Preparation Example 1 except that the protective layer coating solution was changed to the following composition (referred to as Photoconductor 39).
◎ Protective layer coating solution Trifunctional or higher functional radical polymerizable monomer having no charge transport structure 2 parts {Trimethylolpropane triacrylate (KAYARAD TMPTA, Nippon Kayaku)
Molecular weight: 296, number of functional groups: trifunctional, molecular weight / number of functional groups = 99}
18 parts of radically polymerizable compound having a monofunctional charge transport structure having the following structure (Exemplary Compound No. 54)

Photoinitiator 1 part 1-Hydroxy-cyclohexyl-phenyl-ketone (Irgacure 184, manufactured by Ciba Specialty Chemicals)
Tetrahydrofuran 100 parts

光重合開始剤 １部
１−ヒドロキシ−シクロヘキシル−フェニル−ケトン
（イルガキュア１８４、チバ・スペシャルティ・ケミカルズ製）
テトラヒドロフラン １００部 (Photoconductor Preparation Example 40)
In Photoconductor Preparation Example 1, an electrophotographic photoconductor was prepared in the same manner as Photoconductor Preparation Example 1 except that the protective layer coating solution was changed to the following composition (referred to as Photoconductor 40).
◎ Protective layer coating solution Trifunctional or higher functional radical polymerizable monomer having no charge transporting structure 18 parts {Trimethylolpropane triacrylate (KAYARAD TMPTA, Nippon Kayaku)
Molecular weight: 296, number of functional groups: trifunctional, molecular weight / number of functional groups = 99}
2 parts of radically polymerizable compound having a monofunctional charge transporting structure having the following structure (Exemplary Compound No. 54)

Photoinitiator 1 part 1-Hydroxy-cyclohexyl-phenyl-ketone (Irgacure 184, manufactured by Ciba Specialty Chemicals)
Tetrahydrofuran 100 parts

(Photoconductor Preparation Example 41)
An electrophotographic photoconductor was prepared in the same manner as in Photoconductor Preparation Example 1 except that the protective layer was not provided and the charge transport layer was changed to 28 μm in Photoconductor Preparation Example 1 (referred to as Photoconductor 41).

  About the electrophotographic photoreceptors 1-41 produced as mentioned above, the external appearance was observed visually and the presence or absence of the crack and film | membrane peeling was discriminate | determined. Next, as a solubility test for an organic solvent, one drop of tetrahydrofuran (hereinafter abbreviated as THF) and dichloromethane were dropped, and the change in the surface shape after natural drying was observed. The results are shown in Table 3.

(Photoconductor Preparation Example 42)
The conductive support used in Photoreceptor Preparation Example 1 was changed to an aluminum cylinder (JIS1050) having a diameter of 40 mm, and Dispersion Liquid 2 was used as the charge generation layer coating solution. An electrophotographic photoreceptor was prepared (to be photoreceptor 42).

(Photoconductor Preparation Example 43)
The conductive support used in Photoreceptor Preparation Example 2 was changed to an aluminum cylinder (JIS1050) having a diameter of 40 mm, and Dispersion Liquid 2 was used as the charge generation layer coating solution. An electrophotographic photoreceptor was produced (referred to as photoreceptor 43).

(Photoreceptor Preparation Example 44)
The conductive support used in Photoreceptor Preparation Example 3 was changed to an aluminum cylinder (JIS1050) having a diameter of 40 mm, and Dispersion Liquid 2 was used as the charge generation layer coating solution. An electrophotographic photoreceptor was prepared (referred to as photoreceptor 44).

(Photoconductor Preparation Example 45)
The conductive support used in Photoreceptor Preparation Example 4 was changed to an aluminum cylinder (JIS1050) having a diameter of 40 mm, and Dispersion Liquid 2 was used as the charge generation layer coating solution. An electrophotographic photoreceptor was produced (referred to as photoreceptor 45).

(Photoconductor Preparation Example 46)
The conductive support used in Photoreceptor Preparation Example 30 was changed to an aluminum cylinder (JIS1050) with a diameter of 40 mm, and Dispersion Liquid 2 was used as the charge generation layer coating solution. An electrophotographic photoreceptor was produced (referred to as photoreceptor 46).

(Photoconductor Preparation Example 47)
The conductive support used in Photoreceptor Preparation Example 32 was changed to an aluminum cylinder (JIS1050) with a diameter of 40 mm, and Dispersion Liquid 2 was used as the charge generation layer coating solution, as in Photoreceptor Preparation Example 32. An electrophotographic photoreceptor was prepared (referred to as photoreceptor 47).

(Photoreceptor Preparation Example 48)
The conductive support used in Photoreceptor Preparation Example 34 was changed to an aluminum cylinder (JIS1050) having a diameter of 40 mm, and Dispersion Liquid 2 was used as the charge generation layer coating solution. An electrophotographic photoreceptor was produced (referred to as photoreceptor 48).

(Photoconductor Preparation Example 49)
The conductive support used in Photoreceptor Preparation Example 36 was changed to an aluminum cylinder (JIS1050) having a diameter of 40 mm, and Dispersion Liquid 2 was used as the charge generation layer coating solution. An electrophotographic photoreceptor was produced (referred to as photoreceptor 49).

(Photoreceptor Preparation Example 50)
The conductive support used in Photoreceptor Preparation Example 41 was changed to an aluminum cylinder (JIS1050) with a diameter of 40 mm, and Dispersion Liquid 2 was used as the charge generation layer coating solution. An electrophotographic photoreceptor was prepared (referred to as photoreceptor 50).

(Examples 1-32 and Comparative Examples 1-9)
The electrophotographic photoconductors (photoconductors 1 to 41) of photoconductor production examples 1 to 41 produced as described above are mounted on a process cartridge for an image forming apparatus as shown in FIG. 10 together with a charging member (scorotron charging). 7 is mounted on an image forming apparatus as shown in FIG. 7 (photosensitive linear velocity is 360 mm / sec), charged using a scorotron charging member so that the surface of the photosensitive member becomes −900 V, and an image exposure light source is used. 780 nm semiconductor laser (image writing by polygon mirror, resolution 600 dpi), development was performed by two-component development, and a toner image was directly transferred onto transfer paper using a transfer conveyance belt as a transfer member (using the circuit shown in FIG. 8). And the transfer current was controlled to be constant). An 780 nm LED was used for the charge removal light, and the entire surface of the photoconductor was irradiated with light to remove the charge. Using a chart with a writing rate of 6%, continuous printing of 500,000 sheets was performed at a speed of 65 sheets per minute (the test environment is 22 ° C.-55% RH).

Charging conditions:
Discharge voltage: -6.0 kV
Grid voltage: -970V (surface potential of unexposed portion of photoconductor is -950V)
Development bias: -700V

The following three evaluations were performed after printing 500,000 sheets of images.
(I) Evaluation of background stain A solid white image was output, and rank evaluation was performed from the number and size of black spots generated on the background.
The rank evaluation was performed in four stages, and very good ones were indicated by ◎, good ones by ○, slightly inferior by Δ, and very bad by x.
(Ii) Evaluation of dot formation state Using the test chart shown in FIG. 14, a halftone image (one dot image having a diameter of 60 μm) is formed immediately after the white solid portion, the character portion, and the black solid portion. Observed.
(Iii) As other items, a black solid image was output, and the image density of the solid portion was evaluated. In addition, a halftone image was output and the presence / absence of moiré was evaluated. The item (iii) is listed in Table 4 only when a defect occurs.
Further, before and after printing 500,000 sheets, the film thickness of the photoreceptor was measured to evaluate the amount of wear.
The results are shown in Table 4.

(Comparative Examples 10-50)
The image forming apparatus shown in FIG. 7 is modified so as to provide an intermediate transfer member. In Examples 1 to 32 and Comparative Examples 1 to 9, the toner images formed on the photosensitive member are temporarily transferred to the intermediate transfer member. Evaluations were made in the same manner as in Examples 1 to 32 and Comparative Examples 1 to 9 except that the transfer was made to transfer onto a transfer paper.
In the evaluation, a one-dot image was enlarged and observed with an optical microscope, and compared with the corresponding Examples 1 to 32 and Comparative Examples 1 to 9. The results are shown in Table 4.

(Examples 33 to 35 and Comparative Examples 51 to 55)
For the photoconductors 1 and 30 to 36 having different protective layers, after the previous paper passing test (Examples 1, 27 and 28 and Comparative Examples 4 to 8), under a low temperature and low humidity environment (10 ° C., 15%) RH), using a test chart as shown in FIG. 15 and outputting the image in the direction from the black solid part to the white solid part under the same conditions as in Example 1, printing 50 sheets continuously, Evaluation was performed.
At this time, the image of the 50th white solid portion was visually evaluated. The results are shown in Table 5.

(Examples 36 to 38 and Comparative Examples 56 to 60)
For the photoreceptors 1 and 30 to 36 having different protective layers, following the previous cleaning test (Examples 33 to 35 and Comparative Examples 9 to 13), in a high temperature and high humidity environment (30 ° C.-90% RH), Further, a sheet passing test of 1000 sheets was performed, and image evaluation was performed. The results are shown in Table 6.
In addition, the following three evaluations were implemented after printing 1000 sheets.
(I) Evaluation of background stain A solid white image was output, and rank evaluation was performed from the number and size of black spots generated on the background. The rank evaluation was performed in four stages, and very good ones were indicated by ◎, good ones by ○, slightly inferior by Δ, and very bad by x.
(Ii) Evaluation of image density A black solid image was output, and the image density of the solid part was evaluated. The rank evaluation was performed in four stages, and very good ones were indicated by ◎, good ones by ○, slightly inferior by Δ, and very bad by x.
(Iii) A 1-dot image was output, and the clarity of the dot outline was ranked. The rank evaluation was performed in four stages, and very good ones were indicated by ◎, good ones by ○, slightly inferior by Δ, and very bad by x.

(Example 39)
In Example 1, evaluation was performed in the same manner as in Example 1 except that the transfer condition control was changed to constant voltage control.
(Example 40)
In Example 1, the evaluation was performed in the same manner as in Example 1 except that the feedback mechanism as shown in FIG. 8 was not provided.
(result)
Compared with Example 1, the image of Example 39 produced a slight amount of transfer dust. In addition, the image of Example 40 sometimes caused a decrease in image density based on transfer defects as compared with the image of Example 1. (Both levels are fine).

(Example 41)
In Example 1, the chart used for the paper passing test was changed to a chart with a writing rate of 1%, and continuous printing of 500,000 sheets was performed. At this time, in order to measure the photosensitive member surface potential at the development site of the image forming apparatus shown in FIG. 7 and the photosensitive member surface potential immediately after the transfer, the surface potential meter was modified so that it could be set.
Before and after the paper passing test, the potential of the exposed portion of the photoreceptor at the development site was measured. At this time, in order to measure the surface potential of the exposed portion, the optical writing was performed on the entire surface of the photoconductor.
In the paper passing test in Example 41, the transfer bias was adjusted so that the potential of the non-written portion of the photoconductor after transfer was −150V. In this measurement, optical writing was not performed, and the potential after transfer of the photosensitive member was measured. The results are shown in Table 7.

(Example 42)
In Example 41, a test was performed in the same manner as in Example 41 except that the potential of the non-written portion of the photoconductor after transfer was adjusted to −80V. The results are shown in Table 7.
(Example 43)
In Example 41, a test was performed in the same manner as in Example 41 except that the potential of the non-written portion of the photoconductor after transfer was adjusted to 0V. The results are shown in Table 7.
(Example 44)
In Example 41, the test was performed in the same manner as in Example 41 except that the potential of the non-written portion of the photoconductor after transfer was adjusted to + 70V. The results are shown in Table 7.
(Example 45)
In Example 41, a test was performed in the same manner as in Example 41 except that the potential of the non-written portion of the photoconductor after transfer was adjusted to + 150V. The results are shown in Table 7.
(Example 46)
In Example 41, the test was performed in the same manner as in Example 41 except that the static elimination member was changed from the static elimination lamp to a conductive brush (connected to ground). The results are shown in Table 7.

(Example 47 and Comparative Examples 61-68)
The photoreceptors of photoreceptor preparation examples 42 to 50 manufactured as described above are mounted on a single process cartridge for an image forming apparatus as shown in FIG. 10 together with a charging member (scorotron charger), and further, the full color shown in FIG. It was installed in an image forming apparatus. In the four image forming elements, a charging member is charged by a scorotron type charging member so that the surface potential of the photoreceptor becomes −900 V, and an image exposure light source is a semiconductor laser of 655 nm (image writing by a polygon mirror, resolution 600 dpi), Development is performed by two-component development (spherical toner having a volume average particle diameter of 6.5 μm), and a transfer belt is used as a transfer member, and a toner image is directly transferred onto transfer paper (using a circuit shown in FIG. Control was performed so that it would be constant). Under the above charging conditions, continuous 150,000 sheets were printed using a chart with a writing rate of 6% (the test environment is 22 ° C.-55% RH).

The following four evaluations were performed after printing 150,000 sheets.
(I) Evaluation of background stain A solid white image was output, and rank evaluation was performed from the number and size of black spots generated on the background. The rank evaluation was performed in four stages, and very good ones were indicated by ◎, good ones by ○, slightly inferior by Δ, and very bad by x.
(Ii) Evaluation of dot formation state Using the test chart shown in FIG. 14, a halftone image (one dot image having a diameter of 60 μm) is formed immediately after the white solid portion, the character portion, and the black solid portion. Observed.
(Iii) Evaluation of color reproducibility The same full-color image was output after initial running of the photoconductor and 150,000 sheets, and evaluation of color reproducibility was attempted. The rank evaluation was performed in four stages, and very good ones were indicated by ◎, good ones by ○, slightly inferior by Δ, and very bad by x.
(Iv) As other items, a black solid image was output, and the image density of the solid portion was evaluated. In addition, a halftone image was output and the presence / absence of moiré was evaluated. The item (iv) is listed in Table 8 only when a defect occurs.

(Comparative Examples 69-77)
The full color image forming apparatus shown in FIG. 9 is modified to provide an intermediate transfer member, and in Example 47 and Comparative Examples 61 to 68, the toner image formed on the photosensitive member is temporarily transferred to the intermediate transfer member, and thereafter Evaluation was performed in the same manner as in Example 47 and Comparative Examples 61 to 68 except that the transfer paper was changed to transfer.
In the evaluation, a one-dot image was magnified and observed with an optical microscope, and compared with the corresponding Example 47 and Comparative Examples 61 to 68. The results are shown in Table 8.

(Example 48 and Comparative Examples 78-85)
Regarding the photoreceptors 42 to 50, after performing the previous paper passing test (Example 47 and Comparative Examples 61 to 68), as shown in FIG. 15 in a low temperature and low humidity environment (10 ° C., 15% RH). Using the test chart, an image was output in the direction from the black solid portion to the white solid portion under the same conditions as in Example 47, printing was performed continuously for 50 sheets, and the cleaning property was evaluated. This was done by operating only the station).
At this time, the image of the 50th white solid portion was visually evaluated. The results are shown in Table 9.

It is the schematic for demonstrating a positive afterimage. It is the schematic for demonstrating a negative afterimage. It is a cross-sectional conceptual diagram which shows the structural example of intermediate | middle layer lamination | stacking in the conventional electrophotographic photoreceptor. It is a cross-sectional conceptual diagram which shows the structural example of intermediate | middle layer lamination | stacking in the conventional electrophotographic photoreceptor. It is a figure for demonstrating the electric field strength dependence in dot formation. It is a figure for demonstrating the electric field strength dependence of a dirt rank. 1 is a schematic view for explaining an electrophotographic process and an image forming apparatus of the present invention. It is a diagram showing a transfer circuit capable of constant current control. 1 is a schematic view for explaining a tandem-type full-color image forming apparatus of the present invention. FIG. FIG. 4 is a diagram for explaining a process cartridge for an image forming apparatus according to the present invention. It is a figure showing the layer structure of the electrophotographic photosensitive member used for this invention. It is a figure showing the layer structure of another electrophotographic photosensitive member used for this invention. 4 is a diagram illustrating an XD spectrum of titanyl phthalocyanine synthesized in Synthesis Example 1. FIG. 2 is a test chart used in Example 1. FIG. 42 is a test chart used in Example 33. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Photoconductor 2 Static elimination lamp 3 Charging member 5 Image exposure part 6 Developing unit 7 Pre-transfer charger 8 Registration roller 9 Transfer paper 10 Transfer charger 11 Separation charger 12 Separation claw 13 Pre-cleaning charger 14 Fur brush 15 Cleaning blades 16Y, 16M, 16C , 16K photoconductors 17Y, 17M, 17C, 17K charging members 18Y, 18M, 18C, 18K laser beams 19Y, 19M, 19C, 19K developing members 20Y, 20M, 20C, 20K cleaning members 21Y, 21M, 21C, 21K transfer brush 22 Transfer conveyor belt 23 Registration roller 24 Fixing device 25Y, 25M, 25C, 25K Image forming element 26 Transfer object 27Y, 27M, 27C, 27K Static elimination member 101 Photoconductor 102 Charging means 103 Exposure 104 Present Image means 105 Transfer paper 106 Transfer means 107 Cleaning means 201 Conductive support 202 Filler dispersion layer 203 Resin layer 204 Photosensitive layer 205 Charge blocking layer 206 Moire prevention layer 207 Charge generation layer 208 Charge transport layer 209 Protective layer 300 Photoreceptor 301 Transfer Belt 302 Drive roller 303 Followed roller 304 Bias roller 305 High voltage power supply (power pack)
306 Current detection resistor

Claims (33)

  In an image forming apparatus having at least an electrophotographic photosensitive member, a charging unit, and a transfer member that directly transfers a toner image formed on the electrophotographic photosensitive member to a transfer target, the electrophotographic photosensitive member is conductive. A trifunctional or higher functional radical polymerization in which at least a charge blocking layer, a moire preventing layer, a photosensitive layer, and a protective layer are sequentially laminated on a support, and the protective layer does not have at least a charge transporting structure. An image forming apparatus formed by curing a functional monomer and a radical polymerizable compound having a monofunctional charge transporting structure.   2. The image forming apparatus according to claim 1, wherein the photosensitive layer has a stacked structure in which a charge generation layer and a charge transport layer are sequentially stacked.   The image forming apparatus according to claim 1, wherein the charge blocking layer is made of an insulating material and has a film thickness of less than 2.0 μm and 0.3 μm or more.   The image forming apparatus according to claim 3, wherein the insulating material is polyamide.   The image forming apparatus according to claim 4, wherein the polyamide is N-methoxymethylated nylon.   The image forming apparatus according to claim 1, wherein the moire preventing layer contains an inorganic pigment and a binder resin, and a volume ratio of the two is in a range of 1/1 to 3/1.   The image forming apparatus according to claim 6, wherein the binder resin is a thermosetting resin.   The image forming apparatus according to claim 7, wherein the thermosetting resin is an alkyd / melamine resin mixture.   The image forming apparatus according to claim 8, wherein a mixing ratio of the alkyd resin and the melamine resin is in a range of 5/5 to 8/2 (weight ratio).   The image forming apparatus according to claim 6, wherein the inorganic pigment is titanium oxide.   The titanium oxide is two types of titanium oxides having different average particle diameters. The average particle diameter of the titanium oxide (T1) having the larger average particle diameter is D1, and the average particle diameter of the other titanium oxide (T2) is D2. 11. The image forming apparatus according to claim 10, wherein the relation of 0.2 <(D2 / D1) ≦ 0.5 is satisfied.   The image forming apparatus according to claim 11, wherein an average particle diameter (D2) of the titanium oxide (T2) is 0.05 μm <D2 <0.20 μm.   The image formation according to claim 11 or 12, wherein a mixing ratio (weight ratio) of the two types of titanium oxides having different average particle diameters is 0.2≤T2 / (T1 + T2) ≤0.8. apparatus.   The image forming apparatus according to claim 1, wherein the photosensitive layer or the charge transport layer contains a polycarbonate having at least a triarylamine structure in the main chain and / or side chain.   The image forming apparatus according to claim 1, wherein the protective layer is insoluble in an organic solvent.   16. The functional group of a tri- or higher functional radical polymerizable monomer having no charge transport structure used for the protective layer is an acryloyloxy group and / or a methacryloyloxy group. The image forming apparatus described in 1.   The ratio of molecular weight to the number of functional groups (molecular weight / number of functional groups) in a trifunctional or higher functional radical polymerizable monomer having no charge transporting structure used for the protective layer is 250 or less, characterized in that it is not more than 250. The image forming apparatus according to any one of the above.   The image according to any one of claims 1 to 17, wherein the functional group of the radical polymerizable compound having a monofunctional charge transporting structure used in the protective layer is an acryloyloxy group or a methacryloyloxy group. Forming equipment.   19. The image formation according to claim 1, wherein the charge transporting structure of the radical polymerizable compound having a monofunctional charge transporting structure used for the protective layer is a triarylamine structure. apparatus. The radically polymerizable compound having a monofunctional charge transporting structure used for the protective layer is at least one of the following general formulas (1) and (2). The image forming apparatus described in 1.

{In the formula, R ₁ represents a hydrogen atom, a halogen atom, an alkyl group which may have a substituent, an aralkyl group which may have a substituent, an aryl group which may have a substituent, a cyano group, a nitro group, Group, alkoxy group, —COOR ₇ (R ₇ is a hydrogen atom, an alkyl group which may have a substituent, an aralkyl group which may have a substituent or an aryl group which may have a substituent), halogen Carbonyl group or CONR ₈ R ₉ (R ₈ and R ₉ may have a hydrogen atom, a halogen atom, an alkyl group which may have a substituent, an aralkyl group which may have a substituent, or a substituent. Represents a good aryl group, which may be the same or different, and Ar ₁ and Ar ₂ represent a substituted or unsubstituted arylene group, which may be the same or different. Ar ₃ and Ar ₄ represent a substituted or unsubstituted aryl group, and may be the same or different. X represents a single bond, a substituted or unsubstituted alkylene group, a substituted or unsubstituted cycloalkylene group, a substituted or unsubstituted alkylene ether group, an oxygen atom, a sulfur atom, or a vinylene group. Z represents a substituted or unsubstituted alkylene group, a substituted or unsubstituted alkylene ether divalent group, or an alkyleneoxycarbonyl divalent group. m and n represent an integer of 0 to 3. } The image according to any one of claims 1 to 20, wherein the radical polymerizable compound having a monofunctional charge transporting structure used in the protective layer is at least one of the following general formula (3). Forming equipment.

(Wherein, o, p and q are each an integer of 0 or 1, Ra represents a hydrogen atom or a methyl group, Rb and Rc represent a substituent other than a hydrogen atom and an alkyl group having 1 to 6 carbon atoms, And s and t each represents an integer of 0 to 3. Za is a single bond, a methylene group, an ethylene group,

Represents. )   The component ratio of the trifunctional or higher functional radical polymerizable monomer having no charge transport structure used in the protective layer is 30 to 70% by weight based on the total amount of the protective layer. An image forming apparatus according to claim 1.   23. The component ratio of the radically polymerizable compound having a monofunctional charge transporting structure used in the protective layer is 30 to 70% by weight based on the total amount of the protective layer. The image forming apparatus described.   24. The image forming apparatus according to claim 1, wherein the protective layer curing means is a heating or light energy irradiation means.   25. The image forming apparatus according to claim 1, wherein the transfer current is controlled by constant current control in the image forming apparatus.   The image forming apparatus includes a feedback mechanism that measures a current flowing through the transfer member in the transfer member, and obtains a transfer current flowing through the photosensitive member based on a difference from an output current from a high voltage power source that applies a current to the transfer member. 26. The image forming apparatus according to claim 1, wherein the image forming apparatus is controlled.   27. In the image forming apparatus, the photoreceptor surface potential after transfer in the non-writing portion is 100 V or less as an absolute value of the polarity charged by the charging unit. Image forming apparatus.   27. The image forming apparatus according to claim 1, wherein the surface potential of the photosensitive member after transfer in the non-writing portion is opposite to the polarity charged by the charging unit. .   29. The image according to claim 28, wherein in the image forming apparatus, the surface potential of the photoreceptor after transfer in the non-writing portion is 100 V or less as an absolute value of the reverse polarity of the polarity charged by the charging unit. Forming equipment.   30. The image forming apparatus according to claim 1, wherein an optical static elimination mechanism is not used in the image forming apparatus.   31. The image forming apparatus according to claim 1, wherein an AC superimposed voltage is applied to a charging unit of the electrophotographic apparatus.   32. The image forming apparatus according to claim 1, wherein a plurality of image forming elements including at least a charging unit, an exposing unit, a developing unit, and an electrophotographic photosensitive member are arranged.   2. An apparatus main body and a detachable cartridge are mounted in which an electrophotographic photosensitive member and at least one means selected from charging means, exposure means, developing means, and cleaning means are integrated. 33. The image forming apparatus according to any one of thru 32.

Images