JP2006330580A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a long-life image forming apparatus which achieves higher image quality by faithfully forming an electrostatic latent image of higher definition than that obtained by using a small diameter beam having diameter of 50 μm for a write light source, reduces production of an abnormal image, such as scumming, even after long-term repeated use, and achieves both the higher image quality to maintain the higher quality image and the higher stability. <P>SOLUTION: In the image forming apparatus, an electrophotographic photoreceptor is subjected to charging by a charging means so as to make electric field intensity ≥30 V/μm, optical writing is carried out to the electrophotographic photoreceptor by using a light source of ≤50 μm in beam diameter for an exposure means; the electrophotographic photoreceptor is constituted by successively laminating at least a charge blocking layer, a moire preventive layer, a photosensitive layer and a protective layer on a conductive support, and the protective layer is formed by curing at least a trifunctional or higher functional radical polymerizable monomer not having a charge transfer characteristic structure and a monofunctional radical polymerizable compound having a charge transfer characteristic structure. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention can form a high-definition and high-definition image, and can stably maintain a high-quality image even when used repeatedly. The present invention relates to an image forming apparatus.

  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. 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. Against this background, there is a strong demand for higher image quality of the above-mentioned printers and copiers, and with the rapid spread of high-speed full-color image forming apparatuses in recent years, the opportunity to output not only characters but also images has increased remarkably. Accordingly, higher resolution and higher definition are demanded.

  As described above, in order to realize high image quality of the image forming apparatus, it is necessary to make the electrostatic latent image formed by performing optical writing on the photosensitive member dense. That is, it is important to form an electrostatic latent image with smaller dots than before. The electrostatic latent image obtained by exposing the photoconductor to the electrostatic latent image is inevitably deteriorated at the present time through development, transfer, and fixing processes. The faithful reproduction of the original is important for improving the image quality, and the effect for improving the image quality is also increased.

Conventional techniques for reducing the beam diameter of a writing light source for forming an electrostatic latent image can be broadly classified into two. One is a technique using short-wavelength laser light, which uses a writing light source having an oscillation wavelength of 450 nm or less that oscillates purple to blue. The second is a technique that optically narrows the beam diameter of light emitted from a light source using a conventionally used light source such as a semiconductor laser.
The former is a technology that is expected more and more in the future as the oscillation light source of 450 nm or less progresses. However, since this writing light source has a shorter wavelength than the exposure light source that has been used in the past, there is a problem with this It is thought to occur. First, most of the charge transport materials used in the charge transport layer that have been used so far have a structure in which the π-conjugated system is expanded to improve transport properties, and the material itself is yellow. It is present and is in the absorption region with respect to the writing light wavelength by the short wavelength light source. For this reason, the charge transport material blocks the writing light, and the photosensitivity of the photoreceptor is remarkably lowered. In addition, the charge transport material itself absorbs light, whereby the charge transport material is promoted to deteriorate via an excited state, thereby degrading the function of the photoreceptor itself. Therefore, a charge transport material that transmits light having a wavelength shorter than 450 nm is required.

  The second problem is related to charge generation materials. Light having a wavelength shorter than 450 nm has a high energy as described above, and has a higher energy than that required for the generation of optical carriers. Conventional electrophotographic photoreceptors generally have a function-separated type photosensitive layer structure in which a charge transport layer containing a charge transport material is laminated on a charge generation layer containing a charge generation material. Since most of the charge transport materials that have been conventionally used are yellow, light having a wavelength shorter than 450 nm (for example, ultraviolet light emitted from a charging member, ultraviolet light emitted from a fluorescent lamp, etc.) is a charge transport layer. In other words, the charge generation layer (charge generation material) is not deteriorated by short-wavelength light. However, when a charge transport material that transmits light having a wavelength shorter than 450 nm is used for the charge transport layer, the charge generation layer is directly affected.

FIG. 1 shows a schematic diagram of a photocarrier generation mechanism using an organic charge generating material. As shown in FIG. 1, the generation of photocarriers in the organic charge generating substance is performed through the lowest excited singlet state (S ₁ ). The charge generation material existing in the ground state (S ₀ ) is excited to an excited state by light absorption. At this time, the height (potential) to be launched energetically differs depending on the light energy (that is, wavelength). A charge generating material that has obtained an energy higher than the energy difference between S ₀ and S ₁ is once launched to a higher excited state (S ^* ), and is normally thermally relaxed to the S ₁ state. Is generated. At this time, higher energy than the energy level of the S ₁ (the energy difference between the S ₁ and S ^*) is excess energy, may also be all used for other reactions without being relaxed thermally. The excited state of the organic matter, very is in an active state, in addition to settle thermally S ₁ state is internally relaxed, the excess energy by utilizing react with other materials or (oxidative decomposition, etc.), It also binds between the same molecules and changes the molecular structure (isomerization, etc.). Thus, considering only the reaction process of photocarrier generation, the surplus energy promotes the deterioration of the material, so that high chemical stability is required for the charge generation material.

  From the above, photoreceptors used in image forming apparatuses that use short-wavelength laser light as an exposure light source need to have a long life and high stability of the main materials (charge generating substances, charge transporting substances) that compose them. It becomes.

  On the other hand, the latter technique of optically reducing the beam diameter requires development of an optical system (lens, mirror, etc.), but recently, an LD light source generally used in digital image forming apparatuses has been used so far. The beam diameter can be reduced to 50 μm or less (see, for example, Patent Document 1). The development of such a writing technique makes it possible to develop an existing material technique in developing a photoreceptor, which is very advantageous in terms of cost.

  With the development of the optical system in the image forming apparatus as described above, it has become possible to make the beam diameter much smaller than the conventional one (approximately 60 to 70 μm or more). This has led to the possibility of reducing the dot diameter of the electrostatic latent image formed on the photoreceptor. However, the electrostatic latent image is formed by canceling the charge applied to the photosensitive member by the reverse charge generated by writing, and a small-diameter dot is simply formed by using a small-diameter beam. However, it is also necessary to devise to make use of the small-diameter beam forming technology.

  That is, although the beam diameter irradiated on the charge generation layer by writing with a small-diameter beam is certainly small, optical carriers are generated at a high density in a narrow area because of the high-density writing. These photocarriers are generated as a pair of holes and electrons, but move to the surface of the photoreceptor and the electrode (conductive support) by the electric field applied to the photoreceptor. At this time, the moving direction is determined by the polarity applied to the surface of the photoconductor. However, in the case of the function-separated organic laminated photoconductor, a negative polarity is generally applied to the surface in many cases, and holes are formed on the surface. Electrons will travel in the direction of the electrodes.

  It is known that when charges of the same polarity are close to each other, Coulomb repulsion is caused by the mutual charges, and the case of a photoreceptor is no exception. In particular, when high-density writing is performed as described above, photocarrier generation is performed at high density. Therefore, if charges are not moved smoothly, recombination by holes and electrons (results in a decrease in carrier generation efficiency) In addition, there is a problem that the dots spread when moving through the charge transport layer. As a result, the dot diameter of the electrostatic latent image formed on the surface of the photoreceptor is increased even if the writing is made with a small-diameter beam (see FIG. 2).

  FIG. 3 shows the relationship between the electric field strength applied to the photoreceptor and the dots developed from the electrostatic latent image (writing is performed at 1200 dpi). FIG. 3 shows a toner image when developed using a toner having a sufficiently small particle diameter, but when the electric field strength is low, the dots are large and blurred. This shows the result that carriers generated in the charge generation layer spread due to Coulomb repulsion when crossing the charge transport layer, and the potential contrast corresponding to the writing portion and the non-writing portion on the surface of the photoreceptor is sufficiently high. This shows the results that could not be obtained. Therefore, when forming minute dots by writing such a small-diameter beam, the electric field strength applied to the photoreceptor must be set high. According to the study by the present inventors, application of an electric field strength of 30 V / μm or more is necessary for a normal electrophotographic photosensitive member having a charge transport layer thickness of about 30 μm or less.

However, if the electric field strength is increased more than necessary, the stress on the photoreceptor is increased. FIG. 4 shows the relationship between the electric field strength applied to the photoreceptor and the background stain. The scumming rank in the figure indicates the level of scumming, and the greater the number, the better the level of scumming. As can be seen from the figure, an increase in the electric field strength promotes the occurrence of background contamination, and the background contamination and dot reproducibility (formation of minute dots) have a trade-off relationship with respect to the electric field strength.
Conventionally, in order to avoid scumming, a system is used in which the electric field strength of the photosensitive member is used at 30 V / μm or less, and the reproducibility of small-diameter dots is somewhat sacrificed. For example, in Patent Document 1, 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.

  The electric field strength of the photoreceptor also affects the charge generation efficiency, which greatly affects the high sensitivity and high speed response. In particular, the Bragg angle 2θ diffraction peak (± 0.2 °) for CuKα rays (wavelength 1.542 mm), which is currently known as a highly sensitive charge generating material, has a maximum diffraction peak at least 27.2 °. In the titanyl phthalocyanine crystal, the photocarrier generation efficiency depends on the electric field strength, and the carrier generation efficiency is extremely lowered as the electric field is lowered. Therefore, lowering the electric field intensity can suppress the occurrence of background staining, but has the disadvantages that the dot reproducibility is lowered and the high-speed response is lowered as described above. Such a problem is not a big problem in low resolution (400 dpi or less) writing or a low-speed image forming apparatus, but the resolution is improved (600 dpi or more, finer writing is 1200 dpi or more) and the acceleration is promoted. At present, it has become a very big problem.

In addition, writing with a small-diameter beam is intended for high-density writing. However, as described later, the problem of reciprocity failure of the sensitivity of the photosensitive member at high density occurs, and writing to the small-diameter beam (electrostatic Latent image) The dot outline may be blurred.
Furthermore, when forming a small-diameter dot using a small-diameter beam as described above, if the charge generation layer does not have a sufficiently homogeneous structure, the outline of the fine dot will not be clear, and the advantages of the small-diameter beam are not necessarily obtained. Thus, homogenization of the charge generation layer (that is, miniaturization of the charge generation material particles) has not been considered.

  In view of the above, in an image forming apparatus that forms micro dots using a writing light source with a beam diameter of 50 μm or less, Coulomb repulsion affects the movement of charges in order to improve image quality by taking advantage of the effect. In order to prevent the electric charge from diffusing, it is necessary to sufficiently increase the electric field strength applied to the photoconductor (30 V / μm or more). A high photoreceptor is needed.

  As described above, in order to realize high image quality, it is necessary to improve many image quality deterioration factors in the process or the photoconductor, but that is not sufficient. For example, even if a high-quality image is obtained in the initial stage, if image quality deterioration such as scumming is observed by repeated use, this does not mean that high-quality images have been realized. An image forming apparatus is required to have high image quality, and at the same time, high stability that can maintain the image quality even after repeated use is strongly demanded.

  Furthermore, along with the rapid spread of image forming apparatuses capable of outputting full-color images, there is an increasing demand for speeding up and downsizing of the apparatus, and it is an even more important issue to increase the life of the photoreceptor. . In particular, in order to increase the speed of full-color image output, a tandem-type color image forming apparatus is provided by arranging a plurality of image forming elements such as a photoreceptor and charging, exposing, developing, cleaning, and static eliminating and processing them in parallel. Is effective and is currently the mainstream, but since it includes a plurality of photoconductors and image forming elements, downsizing of the image forming apparatus is a major issue. In order to reduce the size of the image forming apparatus, it is necessary to reduce the diameter of the photoconductor. In this case, the life of the photoconductor is sacrificed. It is necessary to mount a long-life photoconductor that can maintain stable image quality even in use.

  Factors that determine the life of the photoreceptor are roughly divided into two types, one is electrostatic fatigue and one is wear of the surface layer. Both are major problems for the current mainstream organic photoreceptors. The former is derived from changes in the surface potential (charge potential and exposed portion potential) of the photoreceptor when the processes necessary for image formation such as charging and exposure are used repeatedly. In the photoreceptor using organic materials in general, The most serious problem is a decrease in charging potential or an increase in exposure portion potential (sometimes referred to as residual potential). If the charged potential drop or the exposed part potential rise becomes noticeable due to the fatigue of the photoconductor, the background stain may increase or the image density may decrease.

  On the other hand, the latter is a phenomenon in which a layer located on the outermost surface constituting the photoconductor is mechanically worn by sliding of a cleaning member or the like. If 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 the decrease in the thickness of the photosensitive layer, acceleration of electrostatic fatigue, etc. may occur. There is a possibility that the image appears as an abnormal image, or the electric field strength increases due to wear of the photosensitive member, resulting in an increase in background contamination. Therefore, in order to improve the life of the photoreceptor, it is necessary to solve the above two problems at the same time. Especially, most of the image forming apparatuses that are currently popular are those using negative / positive development. It can be said that the most important issue for determining the service life is background stains with countless black spots. In order to form fine dots using a writing light source having a beam diameter of 50 μm or less and realize high definition of image quality, it is essential to suppress background contamination.

  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 is not the essence of the cause. 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 2 includes a cellulose nitrate resin intermediate layer, Patent Document 3 includes a nylon resin intermediate layer, Patent Document 4 includes a maleic acid resin intermediate layer, and Patent Document 5 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 6 includes an intermediate layer in which a carbon or chalcogen-based material is dispersed in a curable resin, and Patent Document 7 includes a thermal polymer intermediate layer using an isocyanate-based curing agent to which a quaternary ammonium salt is added, Patent Document 8 discloses a resin intermediate layer to which a resistance adjusting agent is added, and Patent Document 9 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 10 includes a resin intermediate layer in which an oxide of aluminum or tin is dispersed, Patent Document 11 includes a resin intermediate layer in which conductive particles are dispersed, and Patent Document 12 includes an intermediate layer in which magnetite is dispersed. Patent Document 13 includes a resin intermediate layer in which titanium oxide and tin oxide are dispersed. Patent Document 14, Patent Document 15, Patent Document 16, Patent Document 17, Patent Document 18, Patent Document 19, and the like include calcium, magnesium, aluminum, and the like. An intermediate layer of 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). The layers are laminated in order (see FIG. 5), and the other is a resin layer (203) in which filler is not dispersed on the conductive support (201), a resin layer (202) in which filler is dispersed, and a photosensitive layer (204). Are provided in order (see FIG. 6).

  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 20, Patent Literature 21, Patent Literature 22, Patent Literature 23, Patent Literature 24, Patent Literature 25, Patent Literature 26, Patent Literature 27, Patent Literature 28, 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 29, Patent Document 30, and Patent Document 31 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.

  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 32, Patent Document 33, 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.

  In this way, the structure in which a plurality of undercoat layers or intermediate layers are stacked and functionally separated is highly effective in preventing moire, suppressing soiling, and reducing residual potential. 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 34 discloses a method in which an undercoating layer contains an alkoxymethylated copolymer nylon having an alkoxymethylation degree of 5 to 30%, and Patent Document 35 discloses that an intermediate layer is crosslinked as an inorganic pigment and a binder resin. In Patent Document 36, the undercoat layer is made of N-alkoxymethylated nylon resin, and the elemental concentration of impurities Na, Ca and P atoms contained in the resin is 10 ppm each. The method described below is a method in which Patent Document 37 contains an N-alkoxymethylated polyamide copolymer containing λ-amino-n-lauric acid as a main component in the intermediate layer. A method of incorporating 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 intensity increases as the photoconductor wears, the scumming increases remarkably. Even at high electric field strength, an attempt to enhance the charge blocking function of the undercoat layer or intermediate layer causes a significant increase in residual potential. However, only by suppressing the injection of electric charges from the conductive support by the undercoat layer or the intermediate layer, the background contamination due to repeated use of the photoconductor cannot be completely suppressed. In particular, if the electric field strength is set high mainly for the purpose of improving the image quality, the electric field strength further increases due to wear of the photoreceptor after repeated use, and the influence of soiling and electrostatic fatigue is further increased. Therefore, it is necessary to maintain the electric field strength stably even after repeated use. For this purpose, it is necessary to minimize the variation in film thickness due to abrasion of the photoreceptor.

  Conventional techniques for increasing the wear resistance of the photoreceptor include (i) a material using a curable binder in the cross-linked charge transport layer (see, for example, Patent Document 39), and (ii) a polymer charge transport material. (For example, see Patent Document 40), (iii) those in which an inorganic filler is dispersed in a crosslinked 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. Further, when the unevenness of the inorganic filler and the binder resin on the surface of the photoconductor is large, a cleaning failure may occur, which may cause toner filming or image flow. Furthermore, writing light may be scattered by the inorganic filler, and it is difficult to obtain the effect of using a small-diameter beam. As described above, in the techniques (i), (ii), and (iii), there are defects in residual potential, cleaning properties, etc. even when effective in suppressing soiling, and a small-diameter beam is used. In some cases, it is difficult to obtain the effect of the above, and it has not yet fully satisfied the balance between high image quality and high durability.

  In particular, in recent years, small-diameter toners having a small toner particle diameter and spherical toners having a uniform particle diameter distribution and a nearly spherical shape have begun to be used for high 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 achieve high functionality, and filming and the like based on the additives are likely to occur.

  Such a defect is likely to appear remarkably when the abrasion resistance of the photoreceptor surface layer is improved. This is presumably due to the fact that blade cleaning has cleaned the toner while the surface layer of the photoconductor is worn (scraped off), and this effect is less likely to be manifested by reducing the amount of wear on the surface layer. 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 a 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 undercoat layer or the intermediate layer but also by the abrasion resistance of the photosensitive layer, so that scumming cannot be completely suppressed unless they are improved at the same time. It is difficult to achieve high durability of the photoreceptor. In particular, it is effective to increase the electric field strength in order to achieve high definition of the electrostatic latent image by using a small-diameter beam. However, if the film thickness decreases due to abrasion of the photosensitive layer, the electric field The strength will increase further. Even if the scumming is improved by suppressing charge injection from the conductive support, the scumming of the photosensitive layer will be reduced and accumulation of fatigue will be added. The destruction and the deterioration of the electrostatic characteristics of the photoreceptor are promoted, and the stability of the image quality is remarkably lowered. Therefore, in order to achieve both high image quality and high stability, it is possible to suppress fluctuations in the film thickness of the photosensitive layer and to improve wear resistance while suppressing scumming due to the photoreceptor during repeated use. The generation of abnormal images such as filming and image flow is required to be suppressed.

However, in the prior art, there are few examples that have been studied for high image quality and high stability by combining them. The actual situation is that side effects were observed in image flow and the like, and high image quality after repeated use was not achieved.
JP 2001-154379 A 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 56-48637 A JP-A 64-1728 JP-A-4-281461 Japanese Patent No. 3262488 Japanese Patent No. 3194392 JP 2000-66425 A

An object of the present invention is to achieve high image quality by faithfully forming a higher-definition electrostatic latent image obtained by using a small-diameter beam having a diameter of 50 μm or less as a writing light source, and after long-term repeated use Therefore, it is an object of the present invention to provide a long-life image forming apparatus that has both high image quality and high stability capable of stably maintaining high-quality images with less occurrence of abnormal images such as background stains.
In addition, high-definition image quality is realized, and at the same time, scumming is suppressed even under high electric field strength, the effect of residual potential rise is reduced even after repeated use, and filming, image flow, poor cleaning, etc. It is an object of the present invention to provide a long-life image forming apparatus that achieves both high image quality and high stability in which the occurrence of abnormal images due to the above is suppressed. Another object of the present invention is to provide a process cartridge for an image forming apparatus that is highly durable, highly stable and easy to handle.

  In the image forming apparatus using a light source having a beam diameter of 50 μm or less, the present inventors have realized high image quality, and the occurrence of abnormal images is small even during repeated use, and high-quality images can be produced over a long period of time. As a result of studies for the purpose of stable output, the electrophotographic photosensitive member to be used is at least a charge blocking layer, a moire prevention layer, a photosensitive layer (a charge generation layer and a charge transport layer) and a protective layer on a conductive support. An electrophotographic photosensitive member in which layers are laminated in order, wherein the protective layer includes 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; It has been found that the above problems can be solved by being formed by curing.

  In the prior art, it is already known that the resolution is improved by reducing the beam of writing light and reducing the formed dots. In addition, by increasing the voltage applied to the photoconductor and increasing the electric field strength applied to the photoconductor, the linearity of the movement of the photocarrier generated inside the photoconductor is increased, thereby increasing the dot in the electrostatic latent image. It is already known that the diffusion of If these can be combined, a small-diameter dot (group of photocarriers) is formed inside the photoconductor, and the electric lines of force between the electrode (conductive support) and the photoconductor surface are strengthened, thereby producing a photocarrier. By suppressing the Coulomb repulsion, and moving the optical carrier along the lines of electric force, the shape of the dot written by the small-diameter beam itself can be formed as a photoreceptor surface potential profile (dot of electrostatic latent image).

  However, an increase in the intensity of the electric field applied to the photoconductor promotes charge injection from the conductive support to the photoconductive layer and generation of heat carriers inside the photoconductive layer, and as a result promotes the occurrence of soiling. In general, this phenomenon occurs remarkably when a charge generation material having high photocarrier generation efficiency is used. For example, a diffraction peak (± 0) with a Bragg angle 2θ with respect to a characteristic X-ray (wavelength 1.542 （) of CuKα. In the case of using a titanyl phthalocyanine crystal having a maximum diffraction peak at least 27.2 °, it is actually used in a region where the electric field strength is less than about 30 V / μm.

  Further, it is known that a commonly used photoreceptor is worn by repeated rubbing with toner, paper, and a cleaning blade. If the film thickness of the photosensitive layer decreases with time of use, the electric field strength alone increases, and as a result, the occurrence of background contamination is promoted. Therefore, it is necessary to output an image with an electric field intensity that has little influence on the background stain, which is not sufficient for improving the image quality, and there are many cases where the merit of using a small-diameter beam is not utilized.

As described above, although effective means for controlling the process have been developed, an effective photoconductor that takes advantage of the features has not been developed, so that both high image quality and high stability have not been realized.
The present invention uses a small-diameter beam for higher image quality, increases the electric field strength in order to exert its effect more, enhances the scumming durability mentioned as a side effect, and reduces the wear of the photosensitive layer in repeated use. By suppressing it, it became possible to realize both high image quality and high stability. As a result, a long-life image forming apparatus capable of stably outputting a high-quality image even after repeated use has been completed.

That is, the said subject is solved by following (1)-(29).
(1) In an image forming apparatus including at least a charging unit, an exposure unit, a developing unit, a transfer unit, a fixing unit, and an electrophotographic photosensitive member, an electric field strength defined below is 30 (V / The electrophotographic photosensitive member is charged so as to be equal to or larger than μm), and light is written on the electrophotographic photosensitive member using a light source having a beam diameter of 50 μm or less in the exposure unit. At least a charge blocking layer, a moire prevention layer, a photosensitive layer, and a protective layer are laminated in this order on the conductive support, and the protective layer has at least a trifunctional or higher-functional radical polymerizable monomer and a monofunctional group having no charge transport structure. An image forming apparatus formed by curing a radical polymerizable compound having a charge transporting structure.
Electric field strength (V / μm)
= Surface potential of unexposed portion of photoreceptor at development position (V) / photosensitive layer thickness (μm)

(2) The image forming apparatus according to (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 forming apparatus according to (1) or (2), wherein the charge blocking layer is made of an insulating material and has a thickness of 0.1 μm or more and less than 2.0 μm.
(4) The image forming apparatus according to (3), wherein the insulating material is polyamide.
(5) The image forming apparatus according to (4), wherein the polyamide is N-methoxymethylated nylon.

(6) The moiré prevention layer contains an inorganic pigment and a binder resin, and the volume ratio of the two is in the range of 1/1 to 3/1. Image forming apparatus.
(7) The image forming apparatus according to (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 according to (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).

(10) The image forming apparatus according to any one of (6) to (9), wherein the inorganic pigment is titanium oxide. (11) The inorganic pigment has two or more kinds of inorganic materials having different average primary particle sizes. When the average primary particle diameter of the inorganic pigment having the largest average primary particle diameter is D1 and the average primary particle diameter of the inorganic pigment having the smallest average primary particle diameter is D2, it is 0.2 <( The image forming apparatus according to any one of (6) to (10), wherein a relationship of D2 / D1) ≦ 0.5 is satisfied.
(12) The image forming apparatus according to (11), wherein D2 is 0.05 μm <D2 <0.2 μm.
(13) The mixing ratio (weight ratio) of two or more inorganic pigments having different average primary particle sizes is T1, the content of the inorganic pigment having the largest average primary particle size being T1, and the inorganic having the smallest average primary particle size The image forming apparatus as described in (11) or (12), wherein 0.2 ≦ T2 / (T1 + T2) ≦ 0.8 when the pigment content is T2.

(14) The image formation according to any one of (1) to (13), 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. apparatus.
(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 trifunctional or higher functional radical polymerizable monomer having no charge transporting structure used in the protective layer is an acryloyloxy group and / or a methacryloyloxy group (1) to ( The image forming apparatus according to any one of 15).
(17) The ratio of the 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 transport structure used in the protective layer is 250 or less (1) ) To (16).

(18) Any one of (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 An image forming apparatus according to claim 1.
(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, The image forming apparatus described in 1.

｛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 radically polymerizable compound having a monofunctional charge transporting structure used in the protective layer is at least one of the following general formulas (1) or (2): The image forming apparatus according to any one of 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) Any one of (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): An image forming apparatus according to claim 1.

(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 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. (21) The image forming apparatus according to any one of (21).
(23) The component ratio of the radical polymerizable compound having a monofunctional charge transporting structure used in the protective layer is 30 to 70% by weight with respect to the total amount of the protective layer (1) to (22) ).
(24) The image forming apparatus according to any one of (1) to (23), wherein the protective layer curing means is heating or light energy irradiation means.
(25) The image forming apparatus according to any one of (1) to (24), wherein an AC superimposed voltage is applied to a charging unit of the electrophotographic apparatus.
(26) Any one of (1) to (25), wherein the transfer means used in the image forming apparatus is a direct transfer system that directly transfers a toner image formed on a photoreceptor to a transfer target. An image forming apparatus according to claim 1.

(27) The image forming apparatus according to any one of (1) to (26), 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.
(28) The electrophotographic photosensitive member and at least one means selected from a charging means, an exposure means, a developing means, and a cleaning means are integrated and mounted as a process cartridge that is detachable from the apparatus main body. (1) The image forming apparatus according to any one of (27).
(29) The electrophotographic photosensitive member and at least one means selected from a charging means, an exposure means, a developing means, and a cleaning means are integrated and detachably mounted on the image forming apparatus described in (28). Feature process cartridge.

  In the present invention, the electrophotographic photosensitive member is charged so that the electric field strength is 30 (V / μm) or more, and a light source having a beam diameter of 50 μm or less is used as the exposure means for optical writing on the electrophotographic photosensitive member. The electrophotographic photosensitive member has an undercoat layer in which at least a charge blocking layer and a moire preventing layer are sequentially laminated on a conductive support, and at least a charge transporting structure is formed on the surface of the photosensitive member (photosensitive layer). By using an image forming apparatus having a protective layer formed by curing a radically polymerizable monomer having three or more functional groups and a radically polymerizable compound having a monofunctional charge transporting structure, which is not provided In addition to realizing high image quality of output images, it suppresses the occurrence of image defects such as dirt and scattering, filming, dielectric breakdown, etc. High-quality images can be output stably, and both high image quality and high stability can be realized.

  Along with higher image quality, image defects can be suppressed and wear resistance can be improved, so that the diameter and speed of the photoconductor can be reduced. A big effect is also demonstrated to the conversion. Furthermore, since both high image quality and high stability can be achieved, it is suitable for full-color printing with many opportunities for image output, and is particularly effective for tandem image forming apparatuses that enable high-speed full-color printing. Further, it is possible to reduce the size of the tandem type image forming apparatus in which an increase in the size of the conventional apparatus is inevitable, which is particularly effective.

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) comprises 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.

Any known member can be used as the charging charger (2) 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 used in a non-contact state, they are used in close proximity so that the gap between the photosensitive member surface and the charging member surface is 100 μm or less. If the gap between the photosensitive member and the charging member is too large, the charging is likely to become unstable, and charging unevenness may occur. If the gap is too small, there is toner remaining on the photosensitive member. In such a case, the surface of the charging member may be contaminated. Therefore, the gap is suitably 5 to 100 μm, preferably 10 to 50 μm. The non-contact charging type charging member is not in contact with the photoconductor in the image forming area, so that contamination of the photoconductor can be suppressed, and the charging efficiency is high and the amount of ozone generation is small, which is advantageous for downsizing of the apparatus. Etc. When the dot reproducibility is prioritized for 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 that dielectric breakdown of the photoconductor and carrier adhesion during development may occur, and the upper limit is approximately 60 V / μm or less. Preferably, it is 50 V / μm or less. The contact-type charging member here is a type in which the surface of the charging member comes into contact with the surface of the photosensitive member in the image forming region, and in addition to the charging roller, a charging blade or charging brush having a shape is also used. Can do.
In the present invention, the electric field strength defined by the following formula is used.
Electric field strength (V / μm)
= Surface potential of unexposed portion of photoreceptor at development position (V) / photosensitive layer thickness (μm)

  When a roller-shaped charging member is used, the relationship between the photoreceptor diameter (outer diameter) and the roller diameter (outer diameter) is important. When the photosensitive member diameter is an integral multiple of the roller diameter, the surface of the photosensitive member and the surface of the roller always come into contact with each other in repeated use. There is no particular problem when both are used in a normal state, but if a partial defect or the like occurs on the roller surface, keeping the same photoconductor surface in contact significantly reduces the photoconductor life. It will be. In such a case, if the photosensitive member diameter is not an integral multiple of the roller diameter, the surfaces are always shifted from each other, so that the life is improved by that amount and a desirable result is obtained. Therefore, it is important that the photosensitive member diameter is not an integral multiple of the roller diameter.

  Furthermore, as an application method of charging, there is an advantage that charging unevenness is less likely to occur by using AC superposition, and it can be used satisfactorily. In particular, in the tandem type full-color image forming apparatus described later, in addition to the problem of uneven density of a halftone image due to uneven charging that occurs in the case of a monochrome image forming apparatus, there is a serious problem of deterioration in color balance (color reproducibility). Connected. The above problem is greatly improved by superimposing the AC component on the DC component, but if the AC component conditions (frequency, peak-to-peak voltage) are too large, the hazard to the photoconductor increases. In some cases, deterioration of the photoconductor may be accelerated. For this reason, superposition of alternating current components should be kept to the minimum necessary.

  The frequency of the AC component varies depending on the linear velocity of the photosensitive member, but 3 kHz or less, preferably 2 kHz or less is appropriate. When plotting the relationship between the voltage applied to the charging member and the charging potential to the photoconductor, there is a region where the photoconductor does not charge even though voltage is applied according to Paschen's law. Is recognized. About twice this rising potential is the optimum potential (usually about 1200 to 1500 V) as the peak-to-peak voltage. However, when the charging ability of the photosensitive member is low or the linear velocity is very high, the peak-to-peak voltage twice the rising potential as described above may be insufficient. On the other hand, when the chargeability is good, the potential stability may be sufficiently exhibited even when it is twice or less. Therefore, the peak-to-peak voltage is preferably 3 times or less, more preferably 2 times or less of the rising potential. If the peak-to-peak voltage is rewritten as an absolute value, it is desirably used at 3 kV or less, preferably 2 kV or less, more preferably 1.5 kV or less.

  In addition, the image exposure unit (3) was devised with an optical system capable of ensuring high brightness such as a light emitting diode (LED), a semiconductor laser (LD), and electroluminescence (EL) and capable of writing at 50 μm or less. A light source is used. The above-mentioned contrivance of the optical system is a technique for reducing the writing beam diameter by a method described in, for example, JP-A-2001-154379 (Patent Document 1). In the present invention, the writing beam is 50 μm. Any method can be used as long as it can be formed as follows.

Here, the beam diameter will be described. Usually, the writing light emitted from the optical element is applied to the surface of the photoreceptor through an optical system (mirror or lens). This writing beam does not become a perfect circle, but has a slightly flattened shape like an ellipse. The writing size is determined in the major axis direction of the ellipse, and the beam diameter in the present invention refers to the length of the major axis.
Further, such a beam has a Gaussian distribution from the center of emission, and has a shape as described in Japanese Patent Application Laid-Open No. 2001-154379 (Patent Document 1). Therefore, the long axis cannot be determined without defining the light intensity, but the definition generally used in the present invention is used. That is, the major axis of the region where the amount of light is larger than 1 / e ² of the maximum intensity of the exposure beam is used as the beam diameter of the present invention.

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 at a higher resolution, writing takes longer, so writing with one writing light source is limited by the drum linear speed (process speed). Therefore, when there is one writing light source, the upper limit is about 1200 dpi. When there are a plurality of write light sources, each of them only has to bear a write area, and the upper limit is substantially “1200 dpi × number of write light sources”. 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.
Among these light sources, light emitting diodes and semiconductor lasers have high irradiation energy and long wavelength light of 600 to 800 nm. Therefore, the specific crystal type phthalocyanine pigment which is a charge generation material used in the present invention has high sensitivity. Used well from showing.

  The development unit (4) can handle both regular 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.

  There are two methods in the process of transferring the toner image formed on the photosensitive member to the transfer paper. One is a method for directly transferring the toner image developed on the surface of the photosensitive member as shown in FIG. 7 and the other is a method in which the toner image is once transferred from the photosensitive member to the intermediate transfer member, and this is transferred to the transfer paper. It is the method of transferring to. Either case can be used in the present invention. In particular, a direct transfer system that directly transfers a toner image formed on the surface of the photoreceptor to a transfer target (such as paper to be output) is preferably used.

  The transfer / conveying belt (10) may be a transfer charger or a transfer roller, but it is desirable to use a contact type such as a transfer belt or transfer roller that generates less ozone. 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. As such a transfer member, a known member can be used as long as the structure of the present invention can be satisfied.

  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, in order to increase the life (high durability) of the photoconductor in the image forming apparatus, it is important how to reduce the passing charge amount of the photoconductor.

On the other hand, there is a way of thinking that the photostatic discharge is not performed, but if the main charger is not sufficiently charged, the charging cannot be stabilized and a problem such as an afterimage may occur.
The passing charge of the photoconductor is generated by the movement of the generated optical carrier by light irradiation by the electric potential (the electric field generated thereby) charged on the surface of the photoconductor. Therefore, if the photoreceptor surface potential can be attenuated by means other than light, the amount of charge passing 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.

Use light sources such as fluorescent lamps, tungsten lamps, halogen lamps, mercury lamps, sodium lamps, light-emitting diodes (LEDs), semiconductor lasers (LD), and electroluminescence (EL) as light sources such as static elimination lamps (8). 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 alternating current component is used in the previous charging method or when the residual potential of the photosensitive member 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 having 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 influence of afterimage or the like in the next image forming cycle. In the figure, 9 is a registration roller, 11 is a transfer bias roller, 12 is a separation claw, and 13 is a pre-cleaning charger.

  Further, the toner developed on the photosensitive member (1) by the developing unit (4) is transferred to the transfer paper (7), but when toner remaining on the photosensitive member (1) is generated, a fur brush ( 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. 8 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. 8, reference numerals (1C), (1M), (1Y), and (1K) are drum-shaped photoconductors, and the photoconductors 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 photoreceptors (1C), (1M), (1Y), (1K) rotate in the direction of the arrow in the figure, and charging members (2C), (2M), (2Y), (2K) at least in the order of rotation therearound. ), Developing members (4C), (4M), (4Y), (4K), and cleaning members (5C), (5M), (5Y), (5K). The charging members (2C), (2M), (2Y), and (2K) 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 (2C), (2M), (2Y), (2K) and the developing members (4C), (4M), (4Y), (4K), from an exposure member (not shown) Laser light (3C), (3M), (3Y), and (3K) are irradiated so that an electrostatic latent image is formed on the photoconductors (1C), (1M), (1Y), and (1K). It has become. Then, the four image forming elements (6C), (6M), (6Y), and (6K) centering on the photoreceptors (1C), (1M), (1Y), and (1K) are transferred materials. It is juxtaposed along the transfer conveyance belt (16) which is a conveyance means. The transfer / conveying belt (16) includes developing members (4C), (4M), (4Y), (4K) and cleaning members (5C) of the image forming units (6C), (6M), (6Y), (6K). , (5M), (5Y), and (5K) are in contact with the photoreceptors (1C), (1M), (1Y), and (1K), and contact the back side of the transfer conveyance belt (16) on the photoreceptor side. Transfer brushes (11C), (11M), (11Y), and (11K) for applying a transfer bias are arranged on the surface (back surface). Each of the image forming elements (6C), (6M), (6Y), and (6K) 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. 8, the image forming operation is performed as follows. First, in each of the image forming elements (6C), (6M), (6Y), and (6K), the photoconductors (1C), (1M), (1Y), and (1K) are in the direction indicated by the arrow (the direction along with the photoconductor). ) Is rotated by the charging member (2C), (2M), (2Y), and (2K) 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). The Next, writing is performed at a resolution of 600 dpi or more by laser light (3C), (3M), (3Y), and (3K) with an exposure unit (not shown) arranged outside the photoconductor, and each color to be created is written. An electrostatic latent image corresponding to the image is formed. Also in this case, 1200 dpi writing is generally the upper limit for one writing light source. Next, the latent image is developed by the developing members (4C), (4M), (4Y), and (4K) to form a toner image. Development members (4C), (4M), (4Y), and (4K) are development members that perform development with toners of C (cyan), M (magenta), Y (yellow), and K (black), respectively. The toner images of the respective colors produced on the two photoconductors (1C), (1M), (1Y), and (1K) are superimposed on the transfer paper. The transfer paper (7) is fed out of the tray by the paper feed roller (17), temporarily stopped by the pair of registration rollers (9), and is transferred to the transfer conveyance belt (16) in synchronism with the image formation on the photosensitive member. Sent. The transfer paper (7) held on the transfer conveyance belt (16) is conveyed, and each color at the contact position (transfer section) with each photoconductor (1C), (1M), (1Y), (1K). The toner image is transferred. The toner image on the photoconductor includes transfer bias applied to the transfer brushes (11C), (11M), (11Y), and (11K) and the photoconductors (1C), (1M), (1Y), and (1K). The image is transferred onto the transfer paper (7) by an electric field formed from the potential difference. Then, the transfer paper (7) on which the toner images of four colors are superimposed through the four transfer portions is conveyed to the fixing device (18), where the toner is fixed and discharged to a paper discharge portion (not shown). Further, residual toner remaining on each of the photoconductors (1C), (1M), (1Y), and (1K) without being transferred by the transfer unit is removed from the cleaning devices (5C), (5M), (5Y), ( 5K). In the example of FIG. 8, the image forming elements are arranged in the order of C (cyan), M (magenta), Y (yellow), 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 that stops image forming elements other than black ((6C), (6M), (6Y)). .

Also in this case, it is effective that the photosensitive member diameter is not an integral multiple of the roller diameter. In particular, a tandem type image forming apparatus has a plurality of image forming elements, and eliminating errors as described above is particularly effective when outputting color images.
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 transport structure. It is formed by curing a polymerizable monomer and a radical polymerizable compound having a monofunctional charge transport structure.

  As described above, a light source having a beam diameter of 50 μm or less is used for the image exposure unit (103), and the charging means (102) is 30 V / μm or more (60 V / μm or less, preferably 50 V / μm) with respect to the photoreceptor. (μm or less) electric field strength is applied. In FIG. 7, 104 is a developing unit, 105 is a transfer member, 106 is a transfer unit, and 107 is a cleaning 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 used in 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 is at least It 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.

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 described in JP-A No. 5-100141 (Patent Document 29) and the like as described above. Although it is a technique, in the combination with a photosensitive layer capable of achieving high sensitivity, there are cases where the influence of the generation of heat carriers in the photosensitive layer is large, and it has not always been possible to completely prevent scumming. 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.
Further, as described above, as a technique for improving the wear resistance of the photosensitive member, Japanese Patent Laid-Open No. 56-48637 (Patent Document 39), Japanese Patent Laid-Open No. 64-1728 (Patent Document 40), No. 281461 (Patent Document 41) and the like. 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 for suppressing scumming in the undercoat layer or the protective layer has been disclosed, there are a plurality of scumming factors. It is impossible to withstand. 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.

FIG. 10 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. 11 is a cross-sectional view showing another 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 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, pipes subjected to surface treatment such as cutting, superfinishing, and 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 these undercoat layers is to suppress the 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 undercoat layer is a single layer as usual, the residual potential tends to increase when the charge injection from the conductive support is suppressed, 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 undercoat layers, the scumming suppression effect can be remarkably improved without greatly affecting the residual potential. In the present invention, the effect is exhibited by laminating a plurality of undercoat layers. In particular, an undercoat layer containing no inorganic pigment (charge blocking layer) and an undercoat layer containing an inorganic pigment ( Since at least two layers of moire prevention layers are laminated in this order, there is little influence on the residual potential, and it is possible to greatly enhance the antifouling effect, and there is no side effect on moire and adhesiveness. It is possible to obtain a very large effect for improving the durability.

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. Further, 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 solvent applied to the upper layer is often used as a ketone solvent. In addition, since a uniform film is maintained, the stability and uniformity of the antifouling effect are excellent.

  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. Further, 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, the undercoat 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. have.

  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 undercoat layer is lowered by 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 1.0 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 the undercoat 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 type photoreceptor, the residual potential can be greatly reduced because the undercoat layer has 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 undercoat 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, an inorganic pigment can be selected in a wider range by forming a plurality of undercoat layers composed of a charge blocking layer and a moire preventing layer and separating the functions, but does not contain an inorganic pigment. Even if it has an undercoat layer, the resistance of the inorganic pigment contained in the undercoat layer containing the inorganic pigment has a considerable influence on the background stain 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 thermosetting resins that form a three-dimensional network structure. Among these resins, thermosetting resins are most preferably used because they are hardened and thus have little influence of elution by an organic solvent when a photosensitive layer is coated on the undercoat 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.

  Further, by using two or more kinds of inorganic pigments having different average particle diameters in the moire preventing layer, it is possible to improve the concealing power to the conductive substrate and suppress moire and cause abnormal images. Pinholes can be eliminated. For this purpose, the ratio of the average primary particle diameter D1 of the inorganic pigment having the largest average primary particle diameter of the two or more inorganic pigments to be used to the average primary particle diameter D2 of the inorganic pigment having the smallest average primary particle diameter is used. It is important to be 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, the average particle size of the inorganic pigment (T2) having the smallest average primary particle size relative to the average particle size of the inorganic pigment (T1) having the largest average primary particle size. When the ratio is too small (0.2 ≧ D2 / D1), the activity on the surface of the inorganic pigment is increased, and the electrostatic stability of the electrophotographic photosensitive member is significantly impaired. When the ratio of the average particle diameter of the inorganic pigment (T2) having the smallest average primary particle diameter to the average particle diameter of the inorganic pigment (T1) having the largest average primary particle diameter is too large (D2 / D1> 0. In 5), the hiding power with respect to the conductive substrate is lowered, and the suppressing power against moire and abnormal images is lowered. 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 size of the average particle size (D2) of the inorganic pigment (T2) having the smallest average primary 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.

Further, the mixing ratio (weight ratio) of two or more inorganic pigments having different average primary particle sizes 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 soiling cannot be sufficiently exhibited. 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) are added. In general, it is formed on the substrate by blade coating, dip coating, spray coating, beat coating, nozzle coating or the like. 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-layer 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 is 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.

In the charge generation layer, the pigment is dispersed in a suitable solvent together with a binder resin as necessary using a ball mill, attritor, sand mill, ultrasonic wave, etc., and this is applied onto a conductive support and dried. 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−、−ＳＯ₂−、−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, and 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 the other polymer having an electron donating group include a copolymer of a known monomer, a block polymer, a graft polymer, a star polymer, and, for example, JP-A-3-109460 and JP-A-2000. It is also possible to use a crosslinked polymer having an electron donating group as disclosed in JP-A-206723 and JP-A-2001-34001.
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 transporting structure and a radical polymerizable compound having a monofunctional charge transporting structure.
Since this protective layer has a crosslinked structure obtained by curing a radically polymerizable monomer having three or more functional groups, a three-dimensional network structure is developed, and a highly hard and highly elastic surface layer having a very high crosslinking density can be obtained. In addition, smoothness is high, and high wear resistance and scratch resistance are achieved. Thus, 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, when the entire protective layer is cured, cracks and film peeling tend 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. In the present invention, the aryl group includes a condensed polycyclic hydrocarbon group, a non-condensed cyclic hydrocarbon group, and a heterocyclic group, and includes the following groups.
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の整数を表わす。 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 an integer of 1 to 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.
As the thermal polymerization initiator, 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 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 photoreceptor, and the surface shape of the photoreceptor 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.

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. Additives such as the following antioxidants can be added and are useful.
(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] Cricol 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.

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.
First, a synthesis example of a titanyl phthalocyanine pigment used for the charge generation layer will be described.

(Synthesis Example 1)
A titanyl phthalocyanine crystal was synthesized in accordance with JP 2001-19871 and Example 1. That is, 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. When the dark blue color of the paste changed to light blue (20 minutes after the start of stirring), 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) was 27.2 ± 0.2 °, and the maximum peak and the minimum Titanyl with a peak at an angle of 7.3 ± 0.2 ° and no peak between the peak at 7.3 ° and the peak at 9.4 ° and no peak at 26.3 ° A phthalocyanine powder 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

  A portion 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, and the particle size of titanyl phthalocyanine was measured with a transmission electron microscope. (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. 99 parts (0.91 mol) of trimethylchlorosilane was dropped into this liquid over 1 hour, and the reaction was terminated by stirring for 4 hours and a half at a temperature of about 60 ° C.
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

Next, an example of preparing a dispersion used as a charge generation layer coating solution will be described.
(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、ポリビニルブチラールを溶解した溶媒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 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 PSZ ball with a diameter of 10 mm in a ball mill pot, all of the solvent in which polyvinyl butyral is dissolved and disazo pigment are added, and ball mill dispersion is performed for 5 days. It was.
Here 100 parts 2-butanone,
An additional 200 parts of cyclohexanone was added, and ball mill dispersion was further performed for 1 day to prepare a dispersion liquid (referred to as dispersion liquid 2).

Next, an example of producing an electrophotographic photoreceptor will be described.
(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%),
18.7 parts 2-butanone 140 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 a 6/4 weight ratio.

テトラヒドロフラン ８０部
レベリング剤（メチルフェニルシリコーンオイル、信越化学製） ０．００２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

Tetrahydrofuran 80 parts Leveling agent (Methylphenyl silicone oil, manufactured by Shin-Etsu Chemical) 0.002 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
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)
A photoconductor was prepared in the same manner as in Photoconductor Preparation Example 1 except that the charge blocking layer thickness was 0.2 μm in Photoconductor Preparation Example 1 (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 0.5 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 in Photoconductor Preparation Example 1 except that the thickness of the charge blocking layer was 0.8 μm (referred to as Photoconductor 7).
(Photoreceptor Preparation Example 8)
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 1.6 μm (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 2.1 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 in Photoconductor Preparation Example 1 except that the charge blocking layer coating solution was changed to the following composition and the film thickness was changed to 0.6 μm (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 180 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) 250 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 280 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) 90 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) 262 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 280 parts In the above composition, the volume ratio of the inorganic pigment to the binder resin is 3.1 / 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) 76 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 80 parts In the above composition, the volume ratio of the inorganic pigment to the binder resin is 0.9 / 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%),
Manufactured by 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 the inorganic pigment (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 the inorganic pigment (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: manufactured by Ishihara Sangyo Co., Ltd., average particle size: 0.25 μm)
12.6 parts Titanium oxide (PT-401M: manufactured by 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 (D2 / D1) of the inorganic pigment 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 the inorganic pigment (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 the inorganic pigment (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（平均一次粒径：０．４μｍ） ４部
湿潤分散剤（ＢＹＫ−Ｐ１０４、ＢＹＫケミー社製） ０．０４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 (average primary particle size: 0.4 μm) 4 parts Wetting and dispersing agent (BYK-P104, manufactured by BYK Chemie) 0.04 parts Cyclohexanone 500 parts Tetrahydrofuran 150 parts

アルミナ微粒子（比抵抗：２．５×１０¹²Ω・ｃｍ、平均一次粒径：０．４μｍ）
４部
湿潤分散剤（ＢＹＫ−Ｐ１０４、ＢＹＫケミー社製） ０．０４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 Wetting and dispersing agent (BYK-P104, manufactured by BYK Chemie) 0.04 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 a bifunctional radical polymerizable monomer 10 having no charge transporting structure described below. 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).
(Photoconductor Preparation Example 42)
In Photoconductor Preparation Example 41, an electrophotographic photoconductor was prepared in the same manner as Photoconductor Preparation Example 41 except that the charge blocking layer was not provided (referred to as Photoconductor 42).

  About the electrophotographic photoreceptors 1-42 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 43)
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 43).
(Photoreceptor Preparation Example 44)
The conductive support used in Photoreceptor Preparation Example 2 was changed to an aluminum cylinder (JIS1050) with a diameter of 40 mm, and dispersion 2 was used as the charge generation layer coating solution, as in Photoreceptor Preparation Example 2. An electrophotographic photoreceptor was prepared (referred to as photoreceptor 44).

(Photoconductor Preparation Example 45)
The conductive support used in Photoreceptor Preparation Example 3 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 3. 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 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 47).
(Photoreceptor Preparation Example 48)
The conductive support used in Photoreceptor Preparation Example 42 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 48).

(Examples 1-32 and Comparative Examples 1-66)
The electrophotographic photoconductors (photoconductors 1 to 42) of photoconductor production examples 1 to 42 produced as described above are mounted on a process cartridge for an image forming apparatus as shown in FIG. 9, and an image as shown in FIG. Mounted in a forming apparatus, charged using a scorotron charging member under the following charging conditions, a semiconductor laser having an oscillation wavelength of 655 nm as an image exposure light source, a coupling lens, an aperture, a cylindrical lens, a polygon mirror Then, a beam having a major axis of 45 μm was formed by an image exposure apparatus composed of a scanning lens, and writing was performed on the photosensitive member. A transfer belt was used as the transfer member, and a 780 nm LED was used for the charge removal light, and the entire surface of the photoconductor was irradiated with light to perform charge removal. Under these conditions, continuous printing of 600,000 sheets was performed using a chart with a writing rate of 6% (the test environment is 22 ° C.-55% RH). Further, only the image exposure light source was changed to one having a beam diameter of 60 μm in the major axis, and the image forming apparatus in which the other conditions were exactly the same was similarly printed on 600,000 sheets, and the image quality was compared. .

The charging conditions were the following two conditions.
Charging condition 1:
Discharge voltage: -6.0 kV
Grid voltage: -920V (surface potential of unexposed portion of photoconductor is -900V)
Development bias: -650V
Charging condition 2:
Discharge voltage: -5.8 kV
Grid voltage: -780V (surface potential of unexposed portion of photoconductor is -750V)
Development bias: -500V

After printing 600,000 sheets, the following items were evaluated. The image output after printing 600,000 sheets was performed by resetting the charging conditions so as to obtain the initial electric field strength.
(I) Evaluation of soiling:
A white solid image was output, and rank evaluation was performed from the number and size of black spots generated on the background.
(Ii) Dot reproducibility:
A halftone image was output, the dot formation state on the image was magnified, and rank evaluation was performed for dot reproducibility based on dot scattering, shape, and roughness.
(Iii) Image findings:
Other image evaluation items (image density, moire evaluation, etc.)
Image density evaluation: A black solid image was output, and the image density of the solid part was evaluated.
Moire evaluation: A halftone image was output and the presence or absence of moire was evaluated.
(Iv) Wear amount:
Before and after printing 600,000 sheets, the film thickness of the photoconductor was measured, and the wear amount (μm) was determined from the difference.

In (i) and (ii), the rank evaluation was performed in four stages. Very good ones were indicated by ◎, good ones were indicated by ○, slightly inferior ones were indicated by Δ, and very bad ones were indicated by ×.
The results are shown in Table 4.

(Examples 33 to 38 and Comparative Examples 67 to 68)
Using the photoreceptor 1 produced in the above photoreceptor preparation example 1, the same image forming apparatus as in Example 1 was used, the charging conditions were changed, and the electric field strength applied to the photoreceptor was changed to 20 to 55 V / μm. In this case, background stain, dot reproducibility, and dot outline were evaluated. The evaluation method was implemented as follows.
(I) Evaluation of background dirt:
A white solid image was output, and rank evaluation was performed from the number and size of black spots generated on the background.
(Ii) Evaluation of dot formation state:
A halftone image was formed, and rank evaluation was performed based on the dot scattering state, shape, etc. from the observation results of the dot formation state.
(Iii) Evaluation of dot outline:
A halftone image was formed, the sharpness of the periphery (edge) portion of the dot was observed, and rank evaluation was performed.
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. These results are shown in Table 5.

(Example 39 and Comparative Examples 69 to 79)
The photoconductors of photoconductor preparation examples 43 to 48 manufactured as described above are mounted on a process cartridge for an image forming apparatus as shown in FIG. 9 together with a charging member, and further, a tandem type full-color image forming apparatus shown in FIG. equipped. In the four image forming elements, a charging roller (13 mm in diameter) is used as a charging member, and a 50 μm gap Teflon (registered trademark) tape is attached to a non-image portion of the charging roller so as to be closely arranged in the image area of the photoreceptor. It was. Further, a 655 nm semiconductor laser was used as an image exposure light source, which was arranged in an array on a glass substrate (in the longitudinal direction of the photoconductor), and writing was performed on the surface of the photoconductor via a focusing lens array (the writing beam diameter was 40 μm). A transfer belt was used as the transfer member, and no static elimination light source was provided. This image forming apparatus continuously printed 300,000 sheets using a chart with a writing rate of 6% (the test environment is 22 ° C.-55% RH).

The charging conditions were as follows.
Charging condition 1:
DC bias: -850V
AC bias: 2.0 kV (peak to peak), frequency: 1.5 kHz
Charging condition 2:
DC bias: -700V
AC bias: 2.0 kV (peak to peak), frequency: 1.5 kHz

The following five evaluations were performed after printing 300,000 sheets of images. The results are shown in Table 6.
(I) Evaluation of soiling:
A white solid image was output, and rank evaluation was performed from the number and size of black spots generated on the background.
(Ii) Evaluation of dot reproducibility:
A halftone (one-dot image) was output, the dot formation state was enlarged and observed, and rank evaluation was performed for dot reproducibility and dot scattering state.
(Iii) Evaluation of color reproducibility:
The same full-color image was output after running the initial state of the photoconductor and 300,000 sheets, and an attempt was made to evaluate color reproducibility.
In all cases (i), (ii), and (iii), rank evaluation is performed in four stages, ◎ for very good, ◯ for good, △ for slightly inferior, very bad Was represented by x.
(Iv) As other items, image density evaluation: a black solid image was output, and the solid image density was evaluated. In addition, a halftone image was output and the presence / absence of moiré was evaluated. The item (iv) is shown in Table 6 only when a defect occurs.

It is a schematic diagram of optical carrier generation. It is a schematic diagram showing that the dots diffuse during charge transport. 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. 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. 1 is a schematic view for explaining an electrophotographic process and an image forming apparatus of the present invention. 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.

Explanation of symbols

1, 1C, 1M, 1Y, 1K photoconductor 2, 2C, 2M, 2Y, 2K charging member 3 image exposure unit 3C, 3M, 3Y, 3K laser beam 4 developing unit 4C, 4M, 4Y, 4K developing member 5C, 5M 5Y, 5K Cleaning member 6C, 6M, 6Y, 6K Image forming element 7 Transfer paper 8 Static elimination lamp 9 Registration roller 10 Transfer conveyance belt 11 Transfer bias roller 11C, 11M, 11Y, 11K Transfer brush 12 Separating claw 13 Charger 14 before cleaning Fur brush 15 Cleaning blade 16 Transfer conveyor belt 17 Feed roller 18 Fixing device 101 Photoconductor 102 Charging means 103 Exposure 104 Developing means 105 Transfer body 106 Transfer means 107 Cleaning means 201 Conductive support 202 Filler dispersion layer 203 Resin layer 204 Photosensitive Layer 205 charge blow Kicking layer 206 Moire prevention layer 207 Charge generation layer 208 Charge transport layer 209 Protective layer

Claims (29)

In an image forming apparatus comprising at least a charging unit, an exposure unit, a developing unit, a transfer unit, a fixing unit, and an electrophotographic photosensitive member, an electric field strength defined below is 30 (V / μm) or more by the charging unit. The electrophotographic photosensitive member is charged so that the exposure means is subjected to optical writing using a light source having a beam diameter of 50 μm or less, and the electrophotographic photosensitive member is a conductive support. At least a charge blocking layer, a moire prevention layer, a photosensitive layer, and a protective layer are laminated in this order, and the protective layer has at least a trifunctional or higher functional radical monomer having no charge transporting structure and a monofunctional charge transport. An image forming apparatus formed by curing a radically polymerizable compound having a crystalline structure.
Electric field strength (V / μm)
= Surface potential of unexposed portion of photoreceptor at development position (V) / photosensitive layer thickness (μm)   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 thickness of 0.1 μm or more and less than 2.0 μm.   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 inorganic pigment is a mixture of two or more kinds of inorganic pigments having different average primary particle diameters, the average primary particle diameter of the inorganic pigment having the largest average primary particle diameter is D1, and the inorganic pigment having the smallest average primary particle diameter 11. The image forming apparatus according to claim 6, wherein the relation of 0.2 <(D2 / D1) ≦ 0.5 is satisfied when the average primary particle diameter is D2.   The image forming apparatus according to claim 11, wherein the D2 satisfies 0.05 μm <D2 <0.2 μm.   The mixing ratio (weight ratio) of two or more inorganic pigments having different average primary particle sizes is T1, the content of the inorganic pigment having the largest average primary particle size, and the inclusion of the inorganic pigment having the smallest average primary particle size 13. The image forming apparatus according to claim 11, wherein 0.2 ≦ T2 / (T1 + T2) ≦ 0.8 when the amount is T2.   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 an AC superimposed voltage is applied to a charging unit of the electrophotographic apparatus.   26. The image according to claim 1, wherein the transfer unit used in the image forming apparatus is a direct transfer system that directly transfers a toner image formed on a photoreceptor to a transfer target. Forming equipment.   27. 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. The electrophotographic photosensitive member and at least one means selected from a charging means, an exposure means, a developing means, and a cleaning means are integrated and mounted as a process cartridge that is detachable from the apparatus main body. The image forming apparatus according to any one of items 27 to 27.   The electrophotographic photosensitive member and at least one unit selected from a charging unit, an exposure unit, a developing unit, and a cleaning unit are integrated and detachably mounted on the image forming apparatus according to claim 28. Process cartridge.

Images