JP2009163050A - Electrophotographic photoreceptor, its manufacturing method, image forming apparatus, process cartridge and image forming method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of an electrophotographic photoreceptor capable of obtaining high-definition and high-quality image over a long period of time, and to provide the electrophotographic photoreceptor, an image forming apparatus and a process cartridge, and an image forming method. <P>SOLUTION: The electrophotographic photoreceptor is manufactured by constituting so that a photosensitive layer 33 (for example, successively forming a charge generation layer 35 and a charge transport layer 37 via a middle layer 41) is laminated on a conductive support 31 and a cured resin layer (a polymerizable compound is previously polymerized for curing to make a crosslinked film) is formed thereon and, thereafter, a surface protection layer 39 is formed by bringing a super-critical fluid and/or sub-critical fluid containing at least one of antioxidant into contact with the cured resin layer. By using the electrophotographic photoreceptor, the image forming apparatus and the process cartridge for image forming apparatus are constituted so as to form an image. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an electrophotographic technology applied to a copying machine, a laser printer, a facsimile, and the like. More specifically, the present invention is stable even under severe use environment conditions (for example, exposure to NOx gas, etc.) and extremely high in long-term use. Manufacturing method of an electrophotographic photosensitive member that maintains high durability and stable electrical characteristics, and realizes high reliability in which an abnormal image such as an afterimage does not occur, and an electrophotographic photosensitive member formed using the manufacturing method, The present invention relates to an image forming apparatus, a process cartridge for the image forming apparatus, and an image forming method.

  In recent years, organic photoreceptors (OPCs) have been widely used in copying machines, facsimile machines, laser printers, and complex machines in place of inorganic photoreceptors because of their good performance and various advantages. The reasons for this include the characteristics of OPC, such as (i) optical characteristics such as the light absorption wavelength range and the amount of absorption, (ii) electrical characteristics such as high sensitivity and stable charging characteristics, ( iii) Wide selection range of materials, (iv) Ease of production, (v) Low cost, (vi) Non-toxicity, etc.

  On the other hand, the diameter of the photoconductor has recently been reduced due to the downsizing of the image forming apparatus, and the high speed of the machine and the maintenance-free movement have been added to increase the durability of the photoconductor. From this point of view, organophotoreceptors are generally soft because the surface layer is mainly composed of low-molecular charge transport materials and inert polymers, and when used repeatedly in electrophotographic processes, they are mechanically driven by development systems and cleaning systems. There is a drawback that wear is likely to occur due to a typical load.

In addition, due to the demand for higher image quality, the rubber hardness of the cleaning blade and the contact pressure must be increased for the purpose of improving the cleaning property as the particle size of the toner particles is reduced. This also promotes the wear of the photoreceptor. It is a factor.
Such wear of the photoreceptor deteriorates electrical characteristics such as sensitivity deterioration and chargeability, and causes abnormal images such as image density reduction and background stains. Further, scratches where wear is locally generated cause streak-like stain images due to poor cleaning. Under the present circumstances, the wear and scratches are rate-determined and the life of the photoconductor has been replaced.

  Therefore, in order to increase the durability of the organic photoreceptor, it is indispensable to reduce the above-described wear amount and maintain stable electric characteristics for a long period of time. For this reason, in order to impart further excellent cleaning properties and transfer properties, an organic photoreceptor having a good surface property is required, and these are the most pressing issues in this field.

Techniques for improving the abrasion resistance of the organic photosensitive layer include (1) using a curable binder for the surface layer (Patent Document 1), and (2) using a polymer type charge transport material (Patent Document 2). ), (3) those having an inorganic filler dispersed in the surface layer (Patent Document 3), and the like.
Among these techniques, the one using the curable binder (1) has poor compatibility with the charge transport material, and the residual potential increases due to impurities such as polymerization initiators and unreacted residues, resulting in image density. There is a tendency for the reduction to occur easily. In addition, (2) using a polymer type charge transport material and (3) dispersed inorganic filler are required for organic photoreceptors, although they can improve wear resistance to some extent. The durability has not been fully satisfied. Furthermore, in the case where the inorganic filler (3) is dispersed, the residual potential increases due to charge traps existing on the surface of the inorganic filler, and the image density tends to decrease. These technologies (1), (2), and (3) are sufficient to satisfy the overall durability including the electrical durability and mechanical durability required for the organic photoreceptor. Has not reached.

  Furthermore, a photoreceptor containing a polyfunctional curable acrylate monomer in order to improve the wear resistance and scratch resistance of (1) is also known (Patent Document 4). However, in this photoreceptor, although there is a description that the polyfunctional curable acrylate monomer is contained in the protective layer provided on the photosensitive layer, the protective layer may contain a charge transport material. However, when the surface layer contains a low-molecular charge transporting substance, there is a problem of compatibility with the cured product. In some cases, the molecular charge transport material is precipitated and cracks are generated, and the mechanical strength is also lowered. There is also a description that a polycarbonate resin is contained for improving compatibility, but in this case, the content of the curable acrylic monomer is reduced, and as a result, sufficient wear resistance cannot be achieved. In addition, for photoreceptors that do not contain a charge transport material in the surface layer, there is a description that the film thickness of the surface layer is reduced in order to reduce the exposed area potential, but if the film thickness is reduced, the mechanical life of the photoreceptor is reduced. Shorter. Furthermore, the environmental stability of the charging potential and the exposure portion potential is poor, and the values fluctuate greatly due to the influence of the temperature and humidity environment, and it is not possible to maintain a sufficient value.

A charge transport layer formed by using a coating liquid comprising a monomer having a carbon-carbon double bond, a charge transport material having a carbon-carbon double bond, and a binder resin as an anti-wear technique for an organic photoreceptor instead of the foregoing. The binder resin has a carbon-carbon double bond and is reactive to the charge transport material, and has a double bond. Those having no reactivity are included. This photoconductor is remarkably compatible with wear resistance and good electrical properties. However, 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 the above reaction was poor, and surface unevenness was caused at the time of crosslinking due to layer separation, and a tendency to cause poor cleaning was observed.
In addition to the binder resin preventing the curing of the monomer as described above, what is specifically described as the monomer used in this photoreceptor is a bifunctional one, and this bifunctional monomer is functional. Since the number of groups was small, a sufficient crosslinking density could not be obtained, and the abrasion resistance was not yet satisfactory. In addition, even when a reactive binder is used, it is difficult to achieve both the binding amount and the crosslinking density of the charge transport material due to the low number of functional groups contained in the monomer and the binder resin, The abrasion resistance was not sufficient.

  An organic photoreceptor 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 (Patent Document 6). However, this organophotoreceptor has a bulky hole-transporting compound having two or more chain-polymerizable functional groups, so that distortion occurs in the cured product, resulting in high internal stress, roughening of the surface layer and cracks over time. May occur easily and does not have sufficient durability. In addition, since the strain in the cured product is large, the film density may not be sufficiently improved, and a sufficiently high wear resistance cannot be achieved. Furthermore, since the film density is low, the formation of a dense cross-linked film is not realized, and the characteristics may not be stable due to environmental changes such as oxidizing gas and humidity, and an afterimage occurs as an abnormal image in an actual use environment. There was a thing. That is, stable image output for a long time has not been realized.

  Further, an organic photoreceptor having a cross-linked charge transport layer obtained by curing a tri- or higher functional radical polymerizable monomer having no charge transport structure and a monofunctional radical polymerizable compound having a charge transport structure is also known. (Patent Documents 7 to 20). In these proposals, cracking of the photosensitive layer is suppressed simultaneously with mechanical and electrical durability by using a monofunctional radically polymerizable compound having a charge transporting structure. However, depending on the method of forming the crosslinked surface layer, the film density of the crosslinked charge transport layer may not be sufficiently high. In such a case, formation of a dense crosslinked surface layer is not realized, and oxidizing gas, humidity, etc. The characteristics may not be stable due to environmental changes, and afterimages may occur as abnormal images in an actual use environment.

  In addition, it is known that a plurality of types of antioxidants are added to the crosslinked surface layer coating solution for the purpose of reducing the influence of oxidizing gas (Patent Documents 21 and 22). According to this proposal, although long-term high-quality image formation has been achieved, high energy light is also irradiated to the compound having a charge transporting structure and the antioxidant when the crosslinked surface layer is photocured. For this reason, it is difficult to maintain the sufficiently stable electric characteristics and electrophotographic photosensitive member characteristics because the decomposition of the compounds and antioxidants having such a charge transporting structure is inevitable. In other words, the fact is that high-quality image output over a satisfactory period cannot be maintained.

  In addition, many conventional techniques relating to image forming apparatuses are known for the purpose of solving abnormal images caused by oxidizing gas (Patent Documents 23 and 24). However, it is necessary to provide additional members such as a heater that controls the temperature of the electrophotographic photosensitive member and a member that removes discharge products, all of which leave major problems such as larger equipment, increased power consumption, and higher costs. Yes.

  As described above, both high mechanical durability and long-term stable electrical characteristics have not been achieved even in a photoreceptor having a cross-linked photosensitive layer in which the charge transport structure is chemically bonded in the prior art. Therefore, high-quality image output over a long period of time has not been realized. In other words, it cannot be said that it has sufficient comprehensive characteristics at present.

JP 56-48637 A JP-A 64-1728 JP-A-4-281461 Japanese Patent No. 3262488 Japanese Patent No. 3194392 JP 2000-66425 A JP 2004-302450 A JP 2004-302451 A JP 2004-302452 A Japanese Patent Laid-Open No. 2005-099688 JP-A-2005-107401 JP-A-2005-107490 JP-A-2005-115322 JP 2005-140825 A JP 2005-156784 A JP 2005-157026 A JP 2005-157297 A JP 2005-189821 A JP-A-2005-189828 JP 2006-71856 A JP 2006-99028 A JP 2006-11014 A JP 2006-208996 A JP 2003-76237 A

  The present invention has been made in view of the above-described problems of the prior art, and is not affected even in a harsh environment (for example, exposure to NOx gas, etc.), and has extremely stable electrical characteristics and high mechanical properties over a long period of time. A highly reliable electrophotographic photosensitive member capable of obtaining a high-definition and high-quality image for a long period of time by maintaining mechanical durability, and an electrophotographic photosensitive member formed using the manufacturing method, An object is to provide an image forming apparatus, a process cartridge for the image forming apparatus, and an image forming method using the same.

  As a result of intensive studies to achieve the above object, the present inventors have found that the above problems can be solved by the inventions described in the following [1] to [20], and have reached the present invention. Hereinafter, the present invention will be specifically described.

[1]: In the method for producing an electrophotographic photosensitive member, wherein at least the photosensitive layer and the surface protective layer are sequentially formed on the conductive support.
The surface protective layer is formed by polymerizing a polymerizable compound in advance to obtain a cured resin layer, and then contacting the cured resin layer with a supercritical fluid and / or a subcritical fluid containing at least one antioxidant. This can be solved by a method for producing an electrophotographic photosensitive member.

  [2]: In the method for producing an electrophotographic photosensitive member according to [1], the cured resin layer is formed by photopolymerization of a radical polymerizable compound.

  If a compound having radical polymerizability is used, a cured resin layer can be formed in a short time without being exposed to high temperatures and without being altered or deteriorated. Since it does not contain an antioxidant, the efficiency of the polymerization reaction is high, and a dense cured resin layer can be obtained.

  [3]: The method for producing an electrophotographic photosensitive member according to [1] or [2] above, wherein the supercritical fluid and / or subcritical fluid is carbon dioxide.

  Carbon dioxide can create a supercritical state relatively easily (supercritical pressure: 7.3 MPa, supercritical temperature: 31.0 ° C.), and is suitable for dissolving organic materials such as antioxidants. Since the heat damage is small and the treatment can be performed without being decomposed, it is suitable for the substance injection treatment of an antioxidant or a charge transporting compound to the cured resin layer of the present invention. Moreover, it is particularly preferable in terms of non-flammability, low toxicity and excellent handleability.

  [4]: The method for producing an electrophotographic photosensitive member according to the above [1] or [2], wherein the supercritical fluid and / or subcritical fluid is a mixture containing at least carbon dioxide.

  [5]: The method for producing an electrophotographic photosensitive member according to [4] above, wherein the carbon dioxide-containing mixture is at least one selected from methanol and ethanol.

  [4] If there is a mixture containing carbon dioxide as in [5], for example, carbon dioxide, for example, a solvent (entrainer) having a strong affinity for organic materials, the desired solute (antioxidant) The solubility of the supercritical fluid and / or subcritical fluid can be adjusted with respect to an organic material such as an agent, and the substance injection process can be improved.

  [6]: Content of at least one or more antioxidants contained in the supercritical fluid and / or subcritical fluid in the method for producing an electrophotographic photosensitive member according to any one of [1] to [5] Is 0.5 g / L or more.

  By setting the content of the antioxidant to 0.5 g / L or more, a supercritical fluid and / or subcritical fluid and a cured resin layer (crosslinked surface layer) in a material injection process for obtaining a desired electrophotographic photosensitive member. ) Can be shortened.

  [7]: In the method for producing an electrophotographic photosensitive member according to any one of [1] to [6], the temperature of the supercritical fluid and / or subcritical fluid is 30 to 140 ° C. To do.

  By setting the above temperature range, the solubility and diffusibility of the supercritical fluid and / or subcritical fluid can be maintained well and the injection of the solute (organic material such as antioxidant) into the crosslinked surface layer can be facilitated. On the other hand, modification and decomposition of the constituent components of the photosensitive layer and the crosslinked surface layer (or surface protective layer) can be avoided, and a desired electrophotographic photoreceptor can be obtained.

  [8]: The method for producing an electrophotographic photosensitive member according to any one of [1] to [7], wherein at least one of the antioxidants is a phenolic antioxidant.

  [9]: The method for producing an electrophotographic photosensitive member according to any one of [1] to [7], wherein at least one of the antioxidants is a phosphorus antioxidant.

  [10]: The method for producing an electrophotographic photosensitive member according to any one of [1] to [7], wherein the at least one or more antioxidants are one or more of phenolic antioxidants and phosphorus antioxidants. One or more agents are selected from the agents.

  According to [8] to [10], radicals generated under the influence of heat, light, gas and the like can be efficiently captured to suppress radical chain reaction. For example, under severe exposure conditions (NOx The image characteristics (for example, afterimage, color balance, etc.) with little influence on gas etc. can be maintained.

  [11]: The method for producing an electrophotographic photosensitive member according to any one of [1] to [10] above, wherein the supercritical fluid and / or the subcritical fluid contains a charge transporting compound. To do.

  [12]: The method for producing an electrophotographic photosensitive member according to [11] above, wherein the charge transporting compound does not have a polymerizable functional group.

  According to [11] or [12], the charge transporting compound can be easily injected into the crosslinked surface layer while avoiding the modification and decomposition of the charge transporting compound. Performance is demonstrated.

  [13]: The method for producing an electrophotographic photosensitive member according to [11] or [12], wherein the charge transporting compound is composed of a compound having a triarylamine structure, a hydrazone structure, a pyrazoline structure, and a carbazole structure. It is selected from.

  [14]: The method for producing an electrophotographic photosensitive member according to any one of [11] to [13] above, wherein the charge transporting compound is a compound having a triarylamine structure.

  According to [13] or [14], even when contained in a supercritical fluid and / or a subcritical fluid, it can be used stably, and good electrical characteristics can be maintained in long-term repeated use. A compound having a reelamine structure is effective because it has a high effect as a charge transport structure and is excellent in injectability into a cured resin layer via a supercritical fluid and / or a subcritical fluid.

  [15]: The method for producing an electrophotographic photosensitive member according to any one of [1] to [14], wherein the polymerizable compound is a compound having no charge transporting structure. .

  [16]: The method for producing an electrophotographic photosensitive member according to any one of [1] to [15], wherein the polymerizable compound has three or more polymerizable functional groups.

  According to [15] or [16], the crosslinking density of the cured resin layer (or the surface protective layer) can be controlled, and both excellent mechanical durability and electrical characteristics can be achieved. For example, the balance between electrical properties and wear resistance can be adjusted in combination with a compound having charge transportability (presence or absence of a polymerizable functional group).

  [17]: The above-described problem is solved by an electrophotographic photosensitive member produced by the production method according to any one of [1] to [16].

  [18]: The above problem is that the electrophotographic photosensitive member according to [17], a charging unit for charging at least the electrophotographic photosensitive member, and an electrostatic latent image on the surface of the electrophotographic photosensitive member charged by the charging unit. A latent image forming unit to be formed; a developing unit for attaching toner to the electrostatic latent image formed by the latent image forming unit; a transfer unit for transferring the toner image formed by the developing unit to a transfer target; The image forming apparatus includes a cleaning unit that removes toner remaining on the surface of the electrophotographic photosensitive member from the surface of the electrophotographic photosensitive member.

  [19]: The problem is that the electrophotographic photosensitive member according to [17], at least a charging unit for charging the electrophotographic photosensitive member, and an electrostatic latent image on the surface of the electrophotographic photosensitive member charged by the charging unit. A latent image forming unit to be formed; a developing unit for attaching toner to the electrostatic latent image formed by the latent image forming unit; a transfer unit for transferring the toner image formed by the developing unit to a transfer target; It has one means selected from the group consisting of cleaning means for removing toner remaining on the surface of the electrophotographic photosensitive member from the surface of the electrophotographic photosensitive member, and is detachable from the main body of the image forming apparatus. This is solved by the process cartridge for the image forming apparatus.

  [20]: The above problem is that at least the electrophotographic photosensitive member according to [17] is charged by a charging unit, and an electrostatic latent image is formed by a latent image forming unit on the surface of the electrophotographic photosensitive member charged by the charging unit. Toner is adhered to the electrostatic latent image formed by the latent image forming means by the developing means, and the toner image formed by the developing means is transferred to the transfer member by the transferring means, and remains on the surface of the electrophotographic photosensitive member after the transfer. The image forming method is characterized in that the toner is removed from the surface of the electrophotographic photosensitive member by a cleaning means to form an image.

According to the method for producing an electrophotographic photosensitive member of the present invention, a surface protective layer is formed by injecting an antioxidant by contacting a supercritical fluid and / or a subcritical fluid with a cured resin layer obtained by polymerizing a polymerizable compound in advance. As a result, the polymerized reaction is not hindered by the antioxidant and a dense cross-linked structure is formed. In addition, there is no problem such as decomposition or alteration of the antioxidant in forming the surface protective layer by applying high energy as in the past. The characteristics of antioxidants are maintained, so that they are not affected even in harsh environments (for example, exposure to NOx gas, etc.), and charge transporting compounds can be injected at the same time, making them extremely stable. Thus, an electrophotographic photosensitive member having high reliability capable of realizing both of the above-described electrical characteristics and high mechanical durability and capable of outputting a high-definition and high-quality image over a long period of time is provided.
According to the electrophotographic photosensitive member of the present invention, it has both a mechanical durability and an electrostatic durability, both of which have been difficult in the past, and is provided with a surface protective layer into which an antioxidant having no decomposition or alteration has been injected. Therefore, there is no deterioration of image characteristics (for example, afterimage and color balance) even in harsh environments, and it can meet the demands for high durability, miniaturization, and high speed of image forming devices. However, image quality deterioration due to wear is small, and high-definition high-quality images can be output stably.
According to the image forming apparatus of the present invention, even when image formation is repeated, the electrical characteristics are extremely stable, the mechanical durability is high, and there is no occurrence of abnormal images such as afterimages. Output is possible. For example, if a tandem image forming apparatus is used, a full-color, high-definition image can be output, and the electrophotographic photosensitive member is less likely to change with time.
According to the process cartridge for an image forming apparatus of the present invention, highly stable image output is possible even in repeated use over a long period of time, and handling is good, and maintainability and reliability are improved.
According to the image forming method of the present invention, even in long-term repeated printing, an abnormal image such as an afterimage is not generated, and a high-definition and high-quality image can be stably obtained.

  As described above, the method for producing an electrophotographic photosensitive member in the present invention is the method for producing an electrophotographic photosensitive member in which at least a photosensitive layer and a surface protective layer are sequentially formed on a conductive support. Is obtained by polymerizing a polymerizable compound in advance to obtain a cured resin layer, and then contacting the cured resin layer with a supercritical fluid and / or a subcritical fluid containing at least one antioxidant. As a result, it was found that an electrophotographic photosensitive member capable of maintaining extremely stable electrical characteristics and high mechanical durability over a long period of time without being affected even in a harsh environment. Hereinafter, the “cured resin layer” may be expressed as a “crosslinked surface layer”.

That is, in the present invention, the crosslinked surface layer after the completion of the polymerization, that is, the crosslinked film is brought into contact with a supercritical fluid and / or a subcritical fluid containing an antioxidant so that the crosslinked structure is sufficiently developed. Since the antioxidant can be injected, the crosslink density is extremely high, a denser surface protective layer can be constructed, and high mechanical durability is realized.
In general, since an antioxidant acts as a radical chain inhibitor, it is known that when a large amount of an antioxidant is mixed, the polymerization of the polymerizable compound is inhibited. However, in the present invention, since the antioxidant is injected after the polymerization of the polymerizable compound, there is no influence of such polymerization inhibition. In addition, when an electrophotographic photosensitive member is produced by the production method of the present invention, it is not necessary to give high energy to the antioxidant in the crosslinked surface layer, the deterioration of the antioxidant in the crosslinked surface layer is extremely small, and it takes a long time. It becomes possible to maintain stable electrical characteristics. This makes it possible to achieve both long-term high mechanical durability and stable electrical characteristics.

Next, the best mode for carrying out the present invention will be described.
First, the supercritical fluid and subcritical fluid will be described. A supercritical fluid refers to a fluid that exceeds the limit temperature and pressure (critical point) at which gas and liquid can coexist. As a characteristic of a supercritical fluid, in a high-density state, the ability to dissolve a substance is generally much larger than the dissolving power of the fluid at room temperature. This is presumably because the fluid is under high pressure, so the kinetic energy of the fluid is large and the viscosity is small. In addition, since the solubility can be controlled by adjusting the density by temperature and pressure, it is also a remarkable characteristic that the application range is wide. In general, a supercritical fluid having a density of 0.2 g / cm ³ or more is often used as a solvent for chemical substances. Also, as described above, the supercritical fluid has a high fluid kinetic energy and a low viscosity, so that the supercritical fluid diffuses quickly into the medium. For this reason, it is known that a generally used solvent does not easily penetrate into the porous body, but if a supercritical fluid is used, it penetrates into the porous body relatively easily. Furthermore, since the thermal conductivity is larger than that of the liquid, it is possible to quickly remove the heat of reaction due to the chemical reaction generated in the supercritical state. In addition, a subcritical fluid is a fluid having a property different from that of gas and liquid in a state in which temperature and / or pressure is lower than a supercritical state determined for each substance, and for each substance. For example, it generally refers to a fluid having a temperature 0 to 30 ° C. lower than the critical point temperature and a pressure 0 to 5 MPa lower than the critical point pressure.

  The supercritical fluid exists as a non-condensable high-density fluid in a temperature / pressure region that exceeds the limit (critical point) where gas and liquid can coexist, does not cause condensation even when compressed, and exceeds the critical temperature. And as long as it is the fluid in the state more than a critical pressure, there will be no restriction | limiting in particular, According to the objective, it can select suitably. Moreover, there is no restriction | limiting in particular as critical temperature and critical pressure of a supercritical fluid.

These fluids include, for example, carbon monoxide, carbon dioxide, ammonia, nitrogen, water, methanol, ethanol, ethane, propane, butane, hexane,
, 3-dimethylbutane, benzene, chlorotrifluoromethane, dimethyl ether and the like, the critical temperature is preferably -273 to 300 ° C, particularly preferably 0 to 140 ° C.

When using a medium that is denatured by heat as a medium to be dissolved in the supercritical fluid, a medium having a low critical temperature is preferable. Examples thereof include carbon dioxide (critical temperature 31.0 ° C.), ethane (critical temperature 32.2 ° C.), propane (critical temperature 96.6 ° C.), ammonia (critical temperature 132.3 ° C.), and the like.
The subcritical fluid is not particularly limited as long as it exists as a high-pressure liquid in the temperature / pressure region near the critical point, and can be appropriately selected according to the purpose. Various materials listed as supercritical fluids can also be suitably used as subcritical fluids. In the present invention, the supercritical fluid and / or the subcritical fluid may be used alone or in combination of two or more.

  When applying a supercritical fluid and / or subcritical fluid to an organic material (eg, antioxidant, charge transporting compound, etc.) as described herein, carbon dioxide is used as the main medium. Is preferred. Carbon dioxide has a supercritical pressure of 7.3 MPa and a supercritical temperature of 31.0 ° C. It can create a supercritical state relatively easily, has little thermal damage to organic materials, and is nonflammable and low-toxic and easy to handle. One advantage is that it is widely used in the food industry.

In order to control the solubility of the organic material described in the present invention in the supercritical fluid and subcritical fluid, an organic solvent can be added to the supercritical fluid and / or subcritical fluid as an entrainer. In general, it is preferable to select, as an entrainer, a solute to be dissolved in a supercritical fluid and / or a subcritical fluid, in the present invention, a solvent having a strong affinity for an organic material. By adding an entrainer, the solubility of the supercritical fluid or subcritical fluid with respect to a desired solute can be adjusted.
There is no restriction | limiting in particular in the solvent used as an entrainer, According to the objective, it can select suitably. Examples include, but are not limited to, methanol, ethanol, acetone, ethyl acetate, propanol, ammonia, melamine, urea, thioethylene glycol, carbon monoxide, nitrogen, water, ethane, propane, and the like.

As described above, an electrophotographic photosensitive member formed by sequentially forming at least a photosensitive layer and a surface protective layer on the conductive support of the present invention is cured after forming a cured resin layer by polymerizing at least a polymerizable compound. By bringing a supercritical fluid and / or a subcritical fluid containing at least one antioxidant into contact with the resin layer, the antioxidant is injected into a cured resin layer having a crosslinked structure (crosslinked surface layer), a so-called crosslinked film. Specifically, a photosensitive layer is provided on a conductive support, and a photosensitive member on which a cured resin layer is further formed is fixed and sealed in a high-pressure cell, and a supercritical fluid containing an antioxidant in the high-pressure cell and By introducing a subcritical fluid and bringing them into contact with each other, an antioxidant is injected into the crosslinked film.
By this treatment, the supercritical fluid and / or subcritical fluid enters the cross-linked film, and the viscosity of the cross-linked film is lowered by plasticizing the cross-linked film, and dissolved in the supercritical fluid and / or subcritical fluid. Antioxidant is inject | poured because antioxidant enters a crosslinked film. In other words, the antioxidant incorporated in the cross-linked film can diffuse relatively quickly in the cross-linked film due to the viscosity decrease due to the large solubility by the supercritical fluid and / or subcritical fluid. Antioxidant is injected to the end.
Therefore, in the present invention, since the antioxidant is injected after the polymerization of the polymerizable compound, there is no decomposition of the antioxidant due to the application of high energy as in the prior art, and thereby the desired function can be imparted. A highly reliable electrophotographic photosensitive member capable of outputting a high-quality image over a long period of time has been realized.

  Next, the antioxidant used in the present invention will be described. It does not restrict | limit especially as antioxidant, According to the objective, it can select suitably from what is generally known as antioxidants, such as a plastics, rubber | gum, and fats and oils. For example, radical antioxidants such as phenolic antioxidants, amine antioxidants, peroxide decomposers such as phosphorus antioxidants, sulfur antioxidants, ultraviolet absorbers, light stabilizers, metal inertness Examples thereof include chain initiation inhibitors such as oxidants and ozone degradation inhibitors.

  The radical chain inhibitor has a function of capturing radicals generated by the influence of heat, light, gas, etc. that strikes the electrophotographic photosensitive member to stop the radical chain reaction. The peroxide decomposing agent has a function of breaking the contribution to the chain reaction by decomposing peroxide (peroxide) resulting from ozone generated when the electrophotographic photosensitive member is charged into an inactive compound. The chain initiation inhibitor has a function of suppressing a chain initiation reaction caused by factors such as light and heat. Specific examples of the antioxidant are shown below.

  Among the radical chain inhibitors, examples of the phenolic antioxidant include 3,5-di-t-butyl-4-hydroxytoluene, 2,6-di-t-butylphenol, and 2,6-di-t. -Butyl-4-ethylphenol, 2,6-di-t-butyl-4-methylphenol, 2,2'-methylenebis (6-t-butyl-4-methylphenol), 4,4'-butylidenebis (6 -T-butyl-3-methylphenol), 4,4'-thiobis (6-t-butyl-3-methylphenol), 2,2'-butylidenebis (6-t-butyl-4-methylphenol), α -Tocopherol, β-tocopherol, 2,2,4-trimethyl-6-hydroxy-7-t-butylchroman, pentaerythrityltetrakis [3- (3,5-di-t-butyl-4-hydride) Loxyphenyl) propionate], 2,2′-thioethylenebis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], 1,6-hexanediol bis [3- (3,5 -Di-t-butyl-4-hydroxyphenyl) propionate], butylhydroxyanisole, dibutylhydroxyanisole, 1- [2-{(3,5-di-butyl-4-hydroxyphenyl) propionyloxy} ethyl] -4 -[3- (3,5-di-butyl-4-hydroxyphenyl) propionyloxy] -2,2,6,6-tetramethylpiperazyl, 2,4-bis- (n-octylthio) -6- ( 4-hydroxy-3,5-di-t-butylanilino) -1,3,5-triazine, 1,3,5-trimethyl-2,4,6-tris (3,5 Di-t-butyl-4-hydroxybenzyl) benzene, 2- (5-methyl-2-hydroxyphenyl) benzotriazole, 2- (3-t-butyl-5-methyl-2-hydroxyphenyl) -5-chloro Benzotriazole, 1- [2- {3- (3,5-di-t-butyl-4-hydroxyphenyl) propionyloxy} ethyl] -4- {3- (3,5-di-t-butyl-4 -Hydroxyphenyl) propionyloxy} -2,2,6,6-tetramethylpiperidine, n-octadecyl-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate, and the like. .

  Among these, those having one or more t-butyl groups on the phenol ring in the molecule are preferable, and among them, those in which the t-butyl group is bonded to the position adjacent to the phenolic hydroxyl group are more preferable. Specific examples thereof include 3,5-di-t-butyl-4-hydroxytoluene, 2,6-di-t-butylphenol, 2,6-di-t-butyl-4-ethylphenol, 2,6 Monophenolic antioxidants such as di-t-butyl-4-methylphenol and n-octadecyl-3- (4'-hydroxy-3 ', 5'-di-t-butylphenyl) propionate; '-Methylenebis (6-tert-butyl-4-methylphenol), 1,3,5-trimethyl-2,4,6-tris (3,5-di-tert-butyl-4-hydroxybenzyl) benzene, penta A polyphenol antioxidant such as erythrityltetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate] is suitable.

In addition, as the radical chain inhibitor, for example, hydroquinones can be used. Specific examples thereof include 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 can be mentioned. Examples of amine-based antioxidants include phenyl-β-naphthylamine, α-naphthylamine, phenothiazine, N, N′-diphenyl-p-phenylenediamine, and tribenzylamine.
Furthermore, among these, 3,5-di-t-butyl-4-hydroxytoluene, n-octadecyl-3- (4′-hydroxy-3 ′, 5′-di-t-butylphenyl) propionate, 1, 3,5-trimethyl-2,4,6-tris (3,5-di-t-butyl-4-hydroxybenzyl) benzene is particularly preferred in terms of electrical properties.

  Among the peroxide decomposers, phosphorus antioxidants include, for example, triphenylphosphine, tri (nonylphenyl) phosphine, tri (dinonylphenyl) phosphine, tricresylphosphine, tri (2, 4-dibutylphenoxy) phosphine, tridecylphosphine, trioctadecylphosphine and the like. Examples of the sulfur-based antioxidant include dilauryl-3,3′-thiodipropionate, distearyl-3,3′-thiodipropionate, ditetradecyl-3,3′-thiodipropionate, laurylstearylthiodipro Pionate, dimyristyl thiodipropionate, 2-mercaptobenzimidazole, etc. are mentioned.

  Furthermore, among the chain reaction initiation inhibitors, examples of the ultraviolet absorber and light stabilizer include phenyl salicylate, monoglycol salicylate, 2-hydroxy-4-methoxybenzophenone, 2- (2′-hydroxy). -5'-methylphenyl) benzotriazole, resorcinol monobenzoate and the like. Examples of the metal deactivator include N-salicyloyl-N′-aldehyde hydrazine, N, N′-diphenyloxamide and the like. Furthermore, examples of the ozone deterioration preventing agent include 6-ethoxy-2,2,4-trimethyl-1,2-dihydroquinoline, N-phenyl-N′-isopropyl-p-phenylenediamine, and the like.

  Furthermore, among these antioxidants, phenolic antioxidants that can suppress deterioration of electrical characteristics are particularly preferable. Among them, 3,5-di-t-butyl-4-hydroxytoluene, octadecyl-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate, 1,3,5-trimethyl-2,4 , 6-Tris (3,5-di-tert-butyl-4-hydroxybenzyl) benzene is good.

  Furthermore, in the present invention, an antioxidant having a radical polymerizable functional group can also be used favorably. Examples of such antioxidants include polymerizable phenolic antioxidants and radical polymerizable hindered amine antioxidants. For example, Sumilizer GM (manufactured by Sumitomo Chemical Co., Ltd.), Sumilizer GS (F) (manufactured by Sumitomo Chemical Co., Ltd.) and the like are commercially available as polymerizable phenolic antioxidants. Moreover, as radically polymerizable hindered amine antioxidants, for example, LA-87 (Asahi Denka Kogyo Co., Ltd.), LA-82 (Asahi Denka Kogyo Co., Ltd.) and the like are commercially available.

  As other radical polymerizable antioxidants, hydroquinone derivatives such as 2,5-di-t-butylhydroquinone, 2,5-dihydroxydiphenylmethane, 2,5-dihydroxydiphenyl, and 2,6-dimethylhydroquinone are used as alkalis. Some are obtained by reacting acryl chloride or methacryl chloride in the solution to form a monoester, and are isolated by column chromatography using a toluene-ethyl acetate mixed solvent as a developing solvent. By using these radical polymerizable antioxidants together with polymerization, it is possible to prevent deterioration of electrical characteristics without lowering the mechanical strength of the crosslinked surface protective layer.

  In addition, an antioxidant may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and a ratio. When two or more kinds of antioxidants are used, the same kind of antioxidants or different kinds of antioxidants may be used, but a phenolic antioxidant which is preferably a radical chain inhibitor It is preferable that at least one of amine-based antioxidants and hydroquinones and at least one of phosphorus-based antioxidants and sulfur-based antioxidants which are peroxide decomposing agents are included. Among these, a combination of a phenolic antioxidant and a phosphorus antioxidant is particularly preferred because it has little side effects on the electrical characteristics of the electrophotographic photosensitive member and good antioxidant ability.

  Moreover, content of antioxidant is arbitrary unless the effect of this invention is impaired remarkably. However, the content of the antioxidant in the crosslinked surface layer is usually preferably from 0.1 to 10% by weight, more preferably from 1 to 5% by weight. If it is less than 0.1%, sufficient antioxidant ability may not be exhibited because the content is too small. If it exceeds 10% by weight, it is not preferable for the electrical characteristics of the electrophotographic photosensitive member, and the potential of the exposed area is increased. May cause side effects.

As described in the specification of the present application, “performed by contacting a cured resin film with a supercritical fluid and / or subcritical fluid containing at least one antioxidant” and “cured resin layer (crosslinked surface layer)” The form is not particularly limited as long as both the “supercritical fluid and / or subcritical fluid containing the antioxidant” are in physical contact.
For example, at least a photosensitive layer and a cured resin layer are provided on a conductive support, which is accommodated in a high-pressure cell, and a certain amount of an antioxidant and a supercritical fluid and / or a subcritical fluid are introduced into the high-pressure cell. After sealing, the supercritical fluid and / or subcritical fluid is removed from the high-pressure cell after a predetermined time. Thus, an antioxidant may be injected into the cured resin layer to form a surface protective layer, which may be taken out as an electrophotographic photosensitive member (Process 1), or an ultra-high pressure cell containing at least one antioxidant. The critical fluid and / or the subcritical fluid may be continuously supplied and discharged, and the electrophotographic photosensitive member may be taken out after a predetermined time (process 2).

  In the former process 1, the amount of the antioxidant introduced into the high-pressure cell is only the amount contained in the supercritical fluid and / or subcritical fluid, and the inside of the cured resin layer of the electrophotographic photosensitive member and the supercritical fluid. And / or the concentration gradient of the antioxidant in the subcritical fluid decreases with time, and the injection rate also decreases as the concentration gradient decreases. As a result, while there is a drawback that the injection rate of the antioxidant into the cured resin film (crosslinked surface layer) is relatively low, the electrophotographic photosensitive member can be manufactured at a low cost with a relatively simple manufacturing facility. There are advantages.

In the latter process 2, since a constant concentration of supercritical fluid and / or subcritical fluid is supplied to the cured resin film (crosslinked surface layer), the inside of the crosslinked surface layer and the supercritical fluid and / or subcritical fluid Since the concentration gradient of the antioxidant is larger than that in the former process, it is possible to inject a desired amount of the antioxidant in a short time. However, since a device for circulating the supercritical fluid and / or subcritical fluid is necessary, and a device for controlling the concentration of the antioxidant in the supercritical fluid and / or subcritical fluid is necessary, the comparison is made. The disadvantage is that a large-scale manufacturing apparatus is required.
In the present invention, any of the above processes can be applied, and can be appropriately selected depending on the purpose.

  The content of the antioxidant in the supercritical fluid and / or subcritical fluid is preferably 0.5 g / L or more, and preferably 1 g / L or more. When it is less than 0.5 g / L, the injection rate of the antioxidant into the crosslinked surface layer is slow, and the time for contacting the supercritical fluid and / or subcritical fluid is long in order to obtain a desired electrophotographic photoreceptor. Become.

The time for which the supercritical fluid and / or subcritical fluid containing the antioxidant is brought into contact with the crosslinked surface layer may be appropriately determined depending on the injection rate of the antioxidant and the thickness of the crosslinked surface layer.
In addition to a solvent that can be expected to have an entrainer effect, a leveling agent or a charge transporting compound that is desired to be contained in the crosslinked surface layer may be dissolved in advance in the supercritical fluid and / or subcritical fluid. This makes it possible to inject these simultaneously with the antioxidant and to realize an electrophotographic photosensitive member having a function desired to be imparted. In addition, in order to suppress removal of substances previously contained in the cross-linked surface layer by contact treatment with supercritical fluid and / or subcritical fluid, the same substance as contained in the cross-linked surface layer is supercritical. It may be preliminarily dissolved in the fluid and / or the subcritical fluid.

  Since the electrophotographic photoreceptor described in the present invention may be altered or decomposed by heat, the temperature in the step of injecting the antioxidant described in the present invention into the cured resin layer (crosslinked surface layer) is preferably Is 30 ° C. or more and 140 ° C. or less, more preferably 30 ° C. or more and 100 ° C. or less. When the temperature is lower than 30 ° C., the solubility and diffusibility of the supercritical fluid and / or subcritical fluid are low, and it is often difficult to inject the antioxidant into the crosslinked surface layer. Exceeding the above range may cause modification / decomposition of the constituent components of the photosensitive layer and the surface protective layer, and, when the electrophotographic photosensitive member is a function-separated type laminated photosensitive member, exudation of constituent components contained in the adjacent layer, etc. This is not preferable because

  In order to more efficiently inject the antioxidant into the cross-linked surface layer, it is preferable that the temperature condition is 5 ° C. higher than the softening point of the antioxidant. In this case, the antioxidant in the supercritical fluid and / or the subcritical fluid melts, so that the concentration in the fluid tends to be uniform. In this case, the antioxidant is likely to enter the crosslinked surface layer whose viscosity has been lowered in the supercritical fluid and / or subcritical fluid. The reason for this phenomenon has not yet been clarified, but even if the concentration of the antioxidant in the supercritical fluid or subcritical fluid is above the saturation state and remains undissolved, it remains in a relatively uniform state in the fluid. It is. Even if the concentration of the antioxidant in the fluid is reduced by injecting the antioxidant into the cross-linked surface layer, the antioxidant that is uniformly dispersed in the fluid quickly dissolves in the fluid. This is considered to be because the concentration of the antioxidant in the fluid maintains a saturated state.

The structure of the electrophotographic photosensitive member of the present invention will be described below including the manufacturing method based on the drawings.
FIG. 1 is a cross-sectional view showing a configuration example of an electrophotographic photosensitive member according to the present invention. A photosensitive layer 33 and a surface protective layer 39 are provided on a conductive support 31.
FIG. 2 is a cross-sectional view showing another configuration example of the electrophotographic photosensitive member according to the present invention. A charge generation layer 35, a charge transport layer 37, and a surface protective layer 39 are provided on the conductive support 31. .
FIG. 3 is a cross-sectional view showing still another configuration of the present invention, in which an intermediate layer 41, a charge generation layer 35, a charge transport layer 37 and a surface protective layer 39 are provided on a conductive support 31.
The surface protective layer 39 of FIGS. 1, 2 and 3 is a supercritical layer in which a polymerizable compound is polymerized in advance to form a cured resin layer (crosslinked surface layer), and then the cured resin layer contains at least one antioxidant. It is formed by contacting a fluid and / or a subcritical fluid.

<Conductive support>
Examples of the conductive support 31 include those having a volume resistance of 10 ¹⁰ Ω · cm or less, for example, metals such as aluminum, nickel, chromium, nichrome, copper, gold, silver, platinum, tin oxide, indium oxide, etc. The metal oxide of the above is coated with film or cylindrical plastic or paper by vapor deposition or sputtering, or a plate made of aluminum, aluminum alloy, nickel, stainless steel or the like and extruded by drawing or drawing. After pipe formation, surface treatment pipes 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 to the above, a conductive support dispersed in a suitable binder resin on the conductive 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-vinylcarbazole, 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.

  Of these, a cylindrical support made of aluminum, which can be easily subjected to the anodic oxide film treatment, can be most preferably used. As used herein, aluminum includes both pure aluminum and aluminum alloys. Specifically, JIS 1000 series, 3000 series, and 6000 series aluminum or aluminum alloy is most suitable. The anodized film is obtained by anodizing various metals and various alloys in an electrolyte solution. Among them, a film called anodized aluminum or an aluminum alloy that has been anodized in an electrolyte solution is used in the present invention. Is the most suitable. In particular, it is excellent in preventing point defects (black spots, background stains) that occur when used in reversal development (negative and positive development).

The anodizing treatment is performed in an acidic bath such as chromic acid, sulfuric acid, oxalic acid, phosphoric acid, boric acid, sulfamic acid. Of these, treatment with a sulfuric acid bath is most suitable. For example, sulfuric acid concentration: 10 to 20%, bath temperature: 5 to 25 ° C., current density: 1 to 4 A / dm ² , electrolytic voltage: 5 to 30 V, treatment time: treatment in the range of about 5 to 60 minutes However, the present invention is not limited to this. Since the anodic oxide film produced in this way is porous and has high insulation, the surface is very unstable.

  For this reason, there is a change with time after fabrication, and the physical property value of the anodized film is likely to change. In order to avoid this, it is preferable to further seal the anodized film. Examples of the sealing treatment include a method of immersing the anodized film in an aqueous solution containing nickel fluoride and nickel acetate, a method of immersing the anodized film in boiling water, and a method of treating with pressurized steam. Among these, the method of immersing in the aqueous solution containing nickel acetate is the most preferable.

  Subsequent to the sealing treatment, the anodic oxide film is washed. The main purpose of this is to remove excess metal salts and the like attached by the sealing treatment. If this remains excessively on the surface of the conductive support (anodized film), not only will it adversely affect the quality of the coating film formed on this surface, but generally low resistance components will remain, so conversely, soiling will occur. It will also cause the occurrence of.

Cleaning may be performed with pure water only once, but usually, multistage cleaning is performed. At this time, it is preferable that the final cleaning liquid is as clean (deionized) as possible. Moreover, it is preferable to perform physical rubbing cleaning with a contact member in one of the multi-stage cleaning processes.
The thickness of the anodized film formed as described above is preferably about 5 to 15 μm. If it is too thin, the barrier effect as an anodic oxide film is not sufficient, and if it is too thick, the time constant as an electrode becomes too large, resulting in the generation of residual potential and the response of the photoreceptor. There is a case.

<Intermediate layer>
In the photoreceptor of the present invention, an intermediate layer can be provided between the conductive support and the charge generation layer constituting the photosensitive layer. The intermediate layer generally contains a resin as a main component, but these resins are preferably resins having a high solvent resistance with respect to a general organic solvent in consideration of applying a photosensitive layer thereon with a solvent. .
Examples of such resins include water-soluble resins such as polyvinyl alcohol, casein, and sodium polyacrylate, alcohol-soluble resins such as copolymer nylon and methoxymethylated nylon, polyurethane, melamine resin, phenol resin, alkyd-melamine resin, and epoxy. Examples thereof include a curable resin that forms a three-dimensional network structure such as a resin. Further, a fine powder pigment of a metal oxide, which can be exemplified by titanium oxide, silica, alumina, zirconium oxide, tin oxide, indium oxide, etc., may be added to the intermediate layer in order to prevent moire or reduce residual potential. .

These intermediate layers can be formed by using an appropriate solvent and coating method like the above-mentioned photosensitive layer. Furthermore, a silane coupling agent, a titanium coupling agent, a chromium coupling agent, or the like can be used as the intermediate layer of the present invention. In addition, in the intermediate layer of the present invention, Al ₂ O ₃ is provided by anodic oxidation, organic matter such as polyparaxylylene (parylene), SiO ₂ , SnO ₂ , TiO ₂ , ITO, CeO _2, etc. Those provided with an inorganic material by a vacuum thin film forming method can also be used satisfactorily. In addition, known ones can be used. The thickness of the intermediate layer is suitably from 0 to 5 μm.

  The intermediate layer 41 has at least a function of preventing injection of reverse polarity charges induced on the electrode side to the photosensitive layer when the photosensitive member is charged, and a function of preventing moire generated when writing with coherent light such as laser light. It has two functions. A function separation type intermediate layer in which this function is separated into two or more layers is an effective means for the photoreceptor used in the present invention. The function separation type intermediate layer of the charge blocking layer and the moire preventing layer will be described below.

(Charge blocking layer)
The charge blocking layer is a layer having a function of preventing reverse polarity charges induced on the electrode (conductive support 31) during charging of the photosensitive member from being injected into the photosensitive layer from the conductive support. 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. The charge blocking layer includes an anodized film typified by an aluminum oxide layer, an inorganic insulating layer typified by SiO, a layer formed from a glassy network of metal oxide, a layer made of polyphosphazene, an aminosilane reaction A layer made of a product, a layer made of an insulating binder resin, a layer made of a curable binder resin, and the like can be given. 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 moiré preventing layer and a photosensitive layer thereon, 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.). And a thermosetting resin obtained by thermally polymerizing a compound containing a plurality of hydrogen groups and a compound containing a plurality of isocyanate groups and / or a compound containing a plurality of epoxy groups.
In this case, the compound containing a plurality of active hydrogens includes, for example, active hydrogens such as polyvinyl butyral, phenoxy resin, phenol resin, polyamide, polyester, polyethylene glycol, polypropylene glycol, polybutylene glycol, and hydroxyethyl methacrylate groups. Acrylic resin to be used.

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. Among these, polyamide is most preferably used from the viewpoint of film formability, environmental stability, solvent resistance, and the like. Of these, N-methoxymethylated nylon is most preferred.
The polyamide resin has a high effect of suppressing charge injection and has little influence on the residual potential. These polyamide resins are alcohol-soluble resins, are insoluble in ketone 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.

  However, 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, causing a decrease in charge and increasing environmental dependence. Was a big issue. However, N-methoxymethylated nylon exhibits high insulation properties, is very excellent in blocking the charge injected from the conductive support, has little effect on the residual potential, and is greatly environmentally dependent. Therefore, even when the use environment of the image forming apparatus is changed, it is possible to always maintain a stable image quality. Therefore, it is most preferably used when an undercoat layer is laminated. 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.
Further, a thermosetting resin obtained by thermally polymerizing an oil-free alkyd resin and an amino resin, for example, a butylated melamine resin, and a polyurethane having an unsaturated bond, a resin having an unsaturated bond such as an unsaturated polyester, A photocurable resin such as a combination with a photopolymerization initiator such as a thioxanthone compound or methylbenzyl formate can also be used as the binder resin.
It also has functions such as the addition of rectifying conductive polymers and acceptor (donor) resins / compounds in accordance with the charge polarity to suppress charge injection from the substrate (conductive support). You may have it.

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

(Moire prevention layer)
The anti-moire layer is a layer having a function of preventing the generation of a moire image due to light interference inside the photosensitive layer when writing with coherent light such as laser light. Basically, it has a function of causing light scattering of the writing light. In order to exhibit such a function, it is effective that the anti-moire layer has a material having a large refractive index. In general, an inorganic pigment and a binder resin (binder resin) are contained, and the inorganic pigment is dispersed in the binder resin. In particular, white pigments are effectively used among inorganic pigments, and for example, titanium oxide, calcium fluoride, calcium oxide, silicon oxide, magnesium oxide, aluminum oxide, and the like are favorably used. Among these, titanium oxide having a large hiding power can be most effectively used.

  Further, in the photoreceptor having the function separation type intermediate layer, the charge blocking layer prevents the charge injection from the conductive support 31, so that at least the charge charged on the surface of the electrophotographic photoreceptor in the moire preventing layer. From the viewpoint of preventing residual potential, it is preferable to have a function of moving charges of the same polarity. For this reason, for example, in the case of a negatively charged type photoreceptor, it is desirable to impart electronic conductivity to the moire prevention layer, and the inorganic pigment to be used is one that has electron conductivity, or one that is conductive. It is desirable to do. Alternatively, the use of an electron conductive material (for example, an acceptor) or the like for the moire preventing layer makes the effect of the present invention more remarkable.

As the binder resin, the same resin as the charge blocking layer can be used. However, in consideration of laminating the photosensitive layer 33 (the charge generation layer 35 and the charge transport layer 37) on the moire prevention layer, the photosensitive layer (charge generation layer) is used. It is important not to be affected by the coating solvent of the layer or the charge transport layer.
A thermosetting resin is preferably used as the binder resin. In particular, alkyd / melamine resin mixtures are best used. 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. If the melamine resin is richer than 5/5, volume shrinkage during thermosetting increases and coating film defects tend to occur, which tends to increase the residual potential of the photoreceptor, which is not desirable. Further, if the alkyd resin is richer than 8/2, although it is effective in reducing the residual potential of the electrophotographic photosensitive member, 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 is 3/1 or more, 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. In addition, when the volume ratio is 3/1 or more, there are cases where the binder resin cannot cover the surface of the inorganic pigment, and direct contact with the charge generation material increases the probability of heat carrier generation, resulting in soiling. It may have an adverse effect on it.

Furthermore, the use of two types of titanium oxide having different average particle diameters in the moire prevention layer can improve the concealing power to the conductive substrate and suppress moire, and can cause abnormal images. The hole can be eliminated. For this purpose, it is important that the average particle size ratio of the two types of titanium oxide used is within a certain range (0.2 <D2 / D1 ≦ 0.5).
When the particle size ratio is outside the range specified in the present invention, that is, when the ratio of the average particle size of the other titanium oxide (T2) to the average particle size of the titanium oxide (T1) having a large average particle size is too small (0. 2> D2 / D1) increases the activity on the titanium oxide surface, and the electrostatic stability of the electrophotographic photosensitive member is significantly impaired. Further, when the ratio of the average particle diameter of the other titanium oxide (T2) to the average particle diameter of one titanium oxide (T1) is too large (D2 / D1> 0.5), the hiding power to the conductive substrate is lowered. In addition, the suppression of moiré and abnormal images is reduced. The average particle size mentioned here is obtained from a particle size distribution measurement obtained when strong dispersion is performed in an aqueous system.

Further, the average particle size (D2) of titanium oxide (T2) having a smaller particle size is an important factor, and it is important that 0.05 μm <D2 <0.20 μm. When it is smaller than 0.05 μm, the hiding power is reduced, and moire may be generated. On the other hand, when it is larger than 0.20 μm, the filling rate of titanium oxide in the moire preventing layer is lowered, and the effect of suppressing soiling cannot be sufficiently exhibited.
The mixing ratio (weight ratio) of the two types of titanium oxide is also an important factor. When T2 / (T1 + T2) is smaller than 0.2, the filling rate of titanium oxide is not so large and the effect of suppressing 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 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 (binder resin) by a conventional method, for example, a ball mill, a sand mill, an attrier or the like, and if necessary, a chemical, a solvent, and an additive necessary for curing (crosslinking) Add a curing accelerator, etc. to make a coating liquid, and use this coating liquid solution on a substrate (conductive support) using conventional methods (blade coating, dip coating, spray coating, beat coating, nozzle coating) Etc.) to form a moire prevention layer. After the coating, it is dried or cured by a curing process such as drying, heating, or light.

<Photosensitive layer>
Next, the photosensitive layer will be described.
The photosensitive layer may be a single-layered photosensitive layer (FIG. 1) containing a charge generation material and a charge transport material, but a layered type (FIGS. 2 and 3) composed of a charge generation layer and a charge transport layer is sensitive. It exhibits excellent durability and is used well. For convenience of explanation, the photosensitive layer having a laminated structure will be described first.

The charge generation layer is a layer mainly composed of a charge generation material. The charge generation material is not particularly limited, and a known material can be used. Among them, titanyl phthalocyanine having a maximum diffraction peak at 27.2 ° as a diffraction peak (± 0.2 °) with a Bragg angle 2θ with respect to the characteristic X-ray (wavelength 1.542 mm) of CuKα can be used effectively. In particular, as a diffraction peak (± 0.2 °) at a Bragg angle 2θ with respect to the characteristic X-ray (wavelength 1.542 mm) of the crystal type and CuKα described in Japanese Patent Laid-Open No. 2001-19871, the maximum diffraction is at least 27.2 °. It has a peak at 9.4 °, 9.6 °, 24.0 °, a peak at 7.3 ° as the lowest diffraction peak, and 7.3 °. A titanyl phthalocyanine crystal having no peak between the peak of 9.4 ° and a peak of 9.4 ° is preferably used, and a crystal having no peak at 26.3 ° can be used effectively.
Furthermore, the titanyl phthalocyanine crystal having the above crystal form, having an average particle size of 0.25 μm or less, and having no coarse particles at the time of crystal synthesis or by dispersion filtration (for example, JP 2004-83859 A, JP 2004-78141) can be most usefully used.

The charge generation layer is prepared by dispersing the charge generation material in a suitable solvent together with a binder resin (binder resin) as necessary using a ball mill, attritor, sand mill, ultrasonic wave, etc. It is formed by coating on a conductive support and drying.
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- Examples include vinyl carbazole, polyacrylamide, polyvinyl benzal, polyester, phenoxy resin, vinyl chloride-vinyl acetate copolymer, polyvinyl acetate, polyphenylene oxide, polyamide, polyvinyl pyridine, cellulose 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 to form a coating solution, which is coated on the charge generation layer and dried. 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., bis-stilbene derivatives, enamine derivatives, etc. Knowledge materials are mentioned. These charge transport materials may be used alone or in combination of two or more.

  Examples of the electron transport material include chloroanil, bromanyl, tetracyanoethylene, tetracyanoquinodimethane, 2,4,7-trinitro-9-fluorenone, 2,4,5,7-tetranitro-9-fluorenone, 2, 4,5,7-tetranitroxanthone, 2,4,8-trinitrothioxanthone, 2,6,8-trinitro-4H-indeno [1,2-b] thiophen-4-one, 1,3,7- Examples thereof include electron-accepting substances such as trinitrodibenzothiophene-5,5-dioxide and benzoquinone derivatives.

As the binder resin, polystyrene, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer, polyester, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, polyvinyl acetate, Polyvinylidene chloride, polyarate, 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, melamine resin, urethane resin, phenol Examples thereof include thermoplastic or thermosetting resins such as resins and 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. The charge transport layer 37 composed of these polymer charge transport materials is excellent in wear resistance. As such a 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 following general formulas (I) to (X) are preferably used. These are illustrated below and specific examples are shown.

[In the formula (I), 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 Is a substituted or unsubstituted aryl group, o, p, q are each independently an integer of 0-4, k, j are compositions, 0.1 ≦ k ≦ 1, 0 ≦ j ≦ 0.9, n Represents the number of repeating units and is an integer of 5 to 5000. X is an aliphatic divalent group, a cycloaliphatic divalent group, or the following general formula (I-1):

[In formula (I-1), 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 divalent group represented by the following general formula (I-2) .

(In Formula (I-2), a represents an integer of 1 to 20, b represents an integer of 1 to 2000, 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. The divalent group represented by this is represented. ]
In the formula (I), two copolymer species are described in the form of an alternating copolymer, but a random copolymer may be used.

[In formula (II), R ₇ ,
R ₈ represents 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 in the case of 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.

Wherein _{(III), R 9, R} 10 is a substituted or unsubstituted aryl _{group, Ar 4, Ar 5, Ar} 6 independently represent an arylene group.
X, k, j, and n are the same as 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.

[In the formula (IV), R ₁₁ and R ₁₂ are substituted or unsubstituted aryl groups, Ar ₇ , Ar ₈ ,
Ar ₉ represents the same or different arylene group, and p represents an integer of 1 to 5. X, k, j and n are the same as in the case of 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.

[In the formula (V), 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 each} represents a substituted or unsubstituted ethylene group or a substituted or unsubstituted vinylene group. X, k, j, and n are the same as 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.

[In the formula (VI), R ₁₅ , R ₁₆ , R ₁₇ and R ₁₈ are substituted or unsubstituted aryl groups, Ar ₁₃ ,
Ar ₁₄ , Ar ₁₅ , Ar ₁₆ are the same or different arylene groups, Y ₁ , Y ₂ , Y ₃ are single bonds, substituted or unsubstituted alkylene groups, substituted or unsubstituted cycloalkylene groups, substituted or unsubstituted alkylenes It represents an ether group, an oxygen atom, a sulfur atom, or a vinylene group, and may be the same or different.
X, k, j, and n are the same as 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.

[In the formula (VII), R ₁₉ and R ₂₀
Represents a hydrogen atom or a substituted or unsubstituted aryl group, and R ₁₉ and R ₂₀ may form a ring. Ar ₁₇ , Ar ₁₈ , Ar ₁₉
Represent the same or different arylene groups. X, k, j, and n are the same as 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.

[In the formula (VIII), R ₂₁ represents a substituted or unsubstituted aryl group, Ar ₂₀ , Ar ₂₁ , Ar ₂₂ , Ar ₂₃
Represent the same or different arylene groups. X, k, j, and n are the same as 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.

[In the formula (IX), 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 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.

[In formula (X), R ₂₆ and R ₂₇ represent a substituted or unsubstituted aryl group, Ar ₂₉ , Ar ₃₀ and Ar ₃₁ represent the same or different arylene groups.
X, k, j, and n are the same as 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 is finally included by carrying out a curing reaction or a crosslinking reaction.

  Further, a charge transport layer having a cross-linked structure is also effectively used as the charge transport layer. Regarding the formation of a cross-linked structure, a reactive monomer having a plurality of cross-linkable functional groups in one molecule is used to cause a cross-linking reaction using light or thermal energy to form a three-dimensional network structure. is there. This network structure functions as a binder resin and exhibits high wear resistance.

  Moreover, it is a very effective means to use a monomer having a charge transporting ability in whole or in part as the reactive monomer. By using such a monomer, a charge transport site is formed in the network structure, and the function as the charge transport layer can be sufficiently expressed. A reactive monomer having a triarylamine structure is effectively used as the monomer having charge transporting ability.

  The charge transport layer having such a network structure has high wear resistance, but has a large volume shrinkage during the crosslinking reaction, and if it is too thick, cracks may occur. In such a case, the charge transport layer has a laminated structure, the lower layer (charge generation layer side) uses a low molecular dispersion polymer charge transport layer, and the upper layer (surface side) has a cross-linked structure. It may be formed.

  A charge transport layer composed of a polymer having these electron donating groups or a polymer having a crosslinked structure is excellent in wear resistance. Usually, in the electrophotographic process, since the charging potential (unexposed portion potential) is constant, if the surface layer of the photoreceptor is worn by repeated use, the electric field strength applied to the photoreceptor increases accordingly. As the electric field strength increases, the occurrence frequency of scumming increases. Therefore, the high wear resistance of the photosensitive member is advantageous for scumming. The charge transport layer composed of a polymer having these electron donating groups is a polymer 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 weight dispersed polymer. It can be configured with 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 response speed.

  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-3-109406, 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.

  In the above description, the photosensitive layer has a laminated structure. 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 formed by providing a single layer containing at least the above-described charge generating substance and a binder resin (binder resin). Those described in the description of the transport layer are preferably used. In addition, when a charge transport material is used in combination with the single-layer photosensitive layer, high photosensitivity, high carrier transport properties, and low residual potential are exhibited, and the single layer photosensitive layer 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.

The surface protective layer in the present invention is formed by bringing a supercritical fluid and / or a subcritical fluid containing at least one antioxidant into contact with a preliminarily formed cured resin layer (crosslinked surface layer). Is formed at least by polymerizing a polymerizable compound. In this case, from the viewpoint of mechanical durability, those having 3 or more polymerizable functional groups are preferably used.
That is, by polymerizing a polymerizable compound having three or more functional groups, a three-dimensional network structure is developed, and a high hardness and high elasticity surface layer having a very high crosslink density is obtained. High wear resistance and scratch resistance are achieved. However, although it is important to increase the crosslink density on the surface of the photoreceptor, that is, the number of crosslink bonds per unit volume in this way, an internal stress due to volume shrinkage occurs because a large number of bonds are instantaneously formed in the polymerization reaction. Since this internal stress increases as the thickness of the crosslinkable protective layer increases, cracks and film peeling tend to occur when the entire surface protective layer is cured. 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.

As a method for solving the above problems, (1) a polymer component is introduced into the crosslinked layer and the crosslinked structure, (2) a large amount of monofunctional and bifunctional radically polymerizable monomers are used, and (3) a flexible group Examples thereof include a method of softening a cured resin layer (crosslinked surface layer), such as using a polyfunctional monomer having. However, in any case, the crosslink density of the cross-linked layer becomes dilute, and dramatic wear resistance is not achieved.
On the other hand, according to the electrophotographic photoreceptor obtained by the production method of the present invention, for example, a surface protection layer having a high crosslinking density in which a three-dimensional network structure is developed on the charge transport layer constituting the photosensitive layer is preferably used. By providing a film thickness of 1 μm or more and 15 μm or less, the above-described cracks and film peeling do not occur, and very high wear resistance is achieved. By making the film thickness of the surface protective layer 2 μm or more and 10 μm or less, in addition to further improving the margin for the above problem, it is possible to select a material for increasing the crosslink density that leads to further improvement in wear resistance. Become.

The reason why the electrophotographic photosensitive member of the present invention can suppress cracks and film peeling is that the surface protective layer can be made thin, so that the internal stress does not increase, and the photosensitive layer or charge transport layer is provided under the surface protective layer. In addition, the internal stress of the surface protective layer can be relaxed.
For this reason, it is not necessary to contain a large amount of the polymer material in the surface protective layer, and scratches or the like caused by incompatibility (resulting from the reaction between the polymer material and the polymerizable composition) caused when the polymer material is contained in a large amount In addition, toner filming hardly occurs.

  Furthermore, in general, when polymerizing a thick film over the entire surface protective layer by energy irradiation, the energy absorption of the antioxidant contained in the surface protective layer limits the energy transmission into the surface protective layer. In some cases, the polymerization reaction may not proceed sufficiently, or the antioxidant may trap a radical generated in the polymerization reaction or may suppress a polymerization phenomenon such as suppressing a polymerization initiation reaction. However, in the surface protective layer of the present invention, since the antioxidant is injected into the cured resin layer (crosslinked surface layer) after the polymerization, there is no polymerization inhibition or deterioration of the antioxidant due to energy irradiation. That is, the curing reaction progresses uniformly to the inside of the surface protective layer, and high abrasion resistance is maintained inside as well as the surface, and stable electrical characteristics can be maintained for a long period of time.

  In the formation of the surface protective layer of the present invention, a charge transporting compound can be contained in addition to the polymerizable compound. In addition, although the presence or absence of the polymerizable functional group of the charge transporting compound does not matter, those having a polymerizable functional group can be preferably used from the viewpoint of mechanical durability. As the charge transporting compound having a polymerizable functional group, a smaller number of functional groups is preferable from the viewpoint of distortion of the cured resin structure and internal stress of the surface protective layer, and a monofunctional charge transporting compound can be used favorably. .

Next, the constituent materials of the surface protective layer coating solution of the present invention will be described.
Among the polymerizable compounds used in the present invention, examples of the polymerizable compound having no charge transport structure include hole transport structures such as triarylamine, hydrazone, pyrazoline, and carbazole, such as condensed polycyclic quinones, It refers to a monomer that does not have an electron transport structure such as diphenoquinone, an electron-withdrawing aromatic ring having a cyano group or a nitro group, and has a polymerizable functional group. The polymerizable functional group may be any group as long as it has a carbon-carbon double bond and can be polymerized. Examples of these polymerizable functional groups include 1-substituted ethylene functional groups and 1,1-substituted ethylene functional groups shown below.

(1) As 1-substituted ethylene functional group, the functional group represented by the following general formula (a) is mentioned, for example.

[In the general formula (a), X ₁ represents an arylene group such as a phenylene group or a naphthylene group optionally having a substituent, an alkenylene group optionally having a substituent, a —CO— group, —COO— group, —CON (R ₁₀ ) — group [wherein R ₁₀ is an alkyl group such as hydrogen, methyl group or ethyl group, aralkyl group such as benzyl group, naphthylmethyl group or phenethyl group, phenyl group, naphthyl group, etc. Represents an aryl group. Or -S- group. ]

  Specific examples of the functional group include a vinyl group, a styryl group, a 2-methyl-1,3-butadienyl group, a vinylcarbonyl group, an acryloyloxy group, an acryloylamide group, and a vinyl thioether group.

(2) Examples of the 1,1-substituted ethylene functional group include functional groups represented by the following general formula (b).

[In the general formula (b), Y represents an alkyl group which may have a substituent, an aralkyl group which may have a substituent, a phenyl group which may have a substituent, naphthyl. An aryl group such as a group, an alkoxy group such as a halogen atom, a cyano group, a nitro group, a methoxy group or an ethoxy group, a —COOR ₁₁ group [R ₁₁ is a hydrogen atom, an optionally substituted methyl group, ethyl An alkyl group such as a group, an aralkyl group such as an optionally substituted benzyl or phenethyl group, an aryl group such as an optionally substituted phenyl group or naphthyl group, or —CONR ₁₂ R ₁₃ ( R ₁₂ and R ₁₃ are each 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 a phenethyl group. Aralkyl group Or a substituent a phenyl group which may have a represents an aryl group such as a naphthyl group, a mutually identical or may be different.). X ₂ represents the same substituent, single bond, and alkylene group as X _{1 in the} general formula (a). However, at least one of Y and X ₂ is an oxycarbonyl group, a cyano group, an alkenylene group, or an aromatic ring. ]

Specific examples of the functional group include an α-acryloyloxy 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 on the substituents for X ₁ , X ₂ , and Y include, for example, halogen groups, nitro groups, cyano groups, methyl groups, ethyl groups and other alkyl groups, methoxy groups, and ethoxy groups. And aryloxy groups such as phenoxy group, aryl groups such as phenyl group and naphthyl group, and aralkyl groups such as benzyl group and phenethyl group.

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

Examples of the polymerizable compound having no charge transporting structure include the following, but are not limited to these compounds.
For example, 2-ethylhexyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, tetrahydrofurfuryl acrylate, 2-ethylhexyl carbitol acrylate, 3-methoxybutyl acrylate, benzyl acrylate, cyclohexyl acrylate, isoamyl acrylate, isobutyl acrylate, methoxy Triethylene glycol acrylate, phenoxytetraethylene glycol acrylate, cetyl acrylate, isostearyl acrylate, stearyl acrylate, styrene monomer, 1,3-butanediol diacrylate, 1,4-butanediol diacrylate, 1,4-butanediol dimethacrylate 1,6-hexanediol diacrylate, 1,6- Xanthdiol dimethacrylate, diethylene glycol diacrylate, neopentyl glycol diacrylate, bisphenol A-EO modified diacrylate, bisphenol F-EO modified diacrylate, neopentyl glycol diacrylate, trimethylolpropane triacrylate (TMPTA), trimethylolpropane tri Methacrylate, trimethylolpropane alkylene-modified triacrylate, trimethylolpropane ethyleneoxy-modified (hereinafter EO-modified) triacrylate, trimethylolpropane propyleneoxy-modified (hereinafter PO-modified) triacrylate, trimethylolpropane caprolactone-modified triacrylate, trimethylolpropane alkylene Modified trimethacrylate, pentaerythritol Acrylate, pentaerythritol tetraacrylate (PETTA), glycerol triacrylate, glycerol epichlorohydrin modified (hereinafter referred to as ECH modified) triacrylate, glycerol EO modified triacrylate, glycerol PO modified triacrylate, tris (acryloxyethyl) isocyanurate, di Pentaerythritol hexaacrylate (DPHA), dipentaerythritol caprolactone modified hexaacrylate, dipentaerythritol hydroxypentaacrylate, alkylated dipentaerythritol pentaacrylate, alkylated dipentaerythritol tetraacrylate, alkylated dipentaerythritol triacrylate, dimethylolpropane Tetraacrylate (DTMPTA), Examples include pentaerythritol ethoxytetraacrylate, phosphoric acid EO-modified triacrylate, 2,2,5,5, -tetrahydroxymethylcyclopentanone tetraacrylate, and these may be used alone or in combination of two or more.

  Further, among the polymerizable compounds used in the present invention, the polymerizable compound having no charge transporting structure is formed with respect to the number of functional groups in the monomer in order to form a dense crosslink in the surface protective layer. The molecular weight ratio (molecular weight / number of functional groups) is preferably 250 or less. If this ratio is greater than 250, the cross-linked surface protective layer tends to be soft and wear resistance tends to be somewhat lowered, so that it has a modifying group such as EO, PO, caprolactone, etc. in the monomers exemplified above. It is not preferable to use a compound having an extremely long modifying group alone.

  The component ratio of the polymerizable monomer having no charge transporting structure used for the surface protective layer is 20% by weight or more, preferably 30% by weight or more based on the total amount of the surface protective layer. If the monomer component is less than 20% by weight, the surface protective layer has a small three-dimensional cross-linking density, and there is a tendency that a drastic improvement in wear resistance cannot be expected as compared with the case of using a conventional thermoplastic binder resin. On the other hand, if it exceeds 80% by weight, the content of the charge transporting compound is lowered, and the electrical characteristics tend to deteriorate. The electrical properties and abrasion resistance required vary depending on the process used, and the film thickness of the surface protective layer of the photoconductor also varies accordingly. Is most preferred.

Any of those having no polymerizable functional group and those having a polymerizable functional group can be used favorably as the charge transporting compound used in the surface protective layer of the present invention.
In terms of electrical characteristics, it is preferred not to include a charge transporting compound when irradiated with light energy. In addition, for the purpose of enhancing the functionality such as improvement of mechanical durability, charge transporting having a polymerizable functional group is preferable. The active compound may also be photocured at the same time.
As the charge transporting compound having no polymerizable functional group, the charge transporting material described in the charge transporting layer is preferably used. In addition, as a compound having a polymerizable functional group, those conventionally known (for example, see JP-A-2005-107401, JP-A-2006-011014, JP-A-2006-15496) are preferably used. Hole transport structures such as hydrazone, pyrazoline, carbazole, etc., for example, condensed polycyclic quinone, diphenoquinone, electron withdrawing aromatic rings having a cyano group or a nitro group, and the like. Refers to a compound having a functional group. Examples of the polymerizable functional group include those described above for the polymerizable monomer having no charge transporting structure, and acryloyloxy group and methacryloyloxy group are particularly useful.

  In addition, a triarylamine structure has a high effect 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 Is well maintained.

[In General Formulas (1) and (2), R ₁ 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. Good aryl group, cyano group, nitro group, alkoxy group, —COOR ₇ (R ₇ has a hydrogen atom, an alkyl group which may have a substituent, an aralkyl group which may have a substituent, or a substituent. Aryl group), a carbonyl halide group or CONR ₈ R ₉ (R ₈ and R ₉ are a hydrogen atom, a halogen 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, which may be the same or different from each other), Ar ₁ and Ar ₂ each represent a substituted or unsubstituted arylene group, May be 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. However, examples of the aralkyl group include a benzyl group, a phenethyl group, and a naphthylmethyl group, and examples of the alkoxy group include a methoxy group, an ethoxy group, and a propoxy group. These include a halogen atom, a nitro group, a cyano group, and a methyl group. Group, alkyl group such as ethyl group, alkoxy group such as methoxy group and ethoxy group, aryloxy group such as phenoxy group, aryl group such as phenyl group and naphthyl group, aralkyl group such as benzyl group and phenethyl group, etc. It may be. Among the substituents for R ₁ , particularly preferred are a hydrogen atom and a methyl group.

Ar ₃ and Ar ₄ represent a substituted or unsubstituted aryl group, and examples of the aryl group include a condensed polycyclic hydrocarbon group, a non-fused cyclic hydrocarbon group, and a heterocyclic group.

  The condensed polycyclic hydrocarbon group preferably has 18 or less carbon atoms forming a ring, for example, a pentanyl group, an indenyl group, a naphthyl group, an azulenyl group, a heptaenyl group, a biphenylenyl group, an as-indacenyl group. , S-indacenyl group, fluorenyl group, acenaphthylenyl group, preadenyl group, acenaphthenyl group, phenalenyl group, phenanthryl group, anthryl group, fluoranthenyl group, acephenanthrenyl group, aceanthrylenyl group, triphenylyl group, pyrenyl group , A chrycenyl group, a naphthacenyl group, and the like.

  Examples of the non-fused cyclic hydrocarbon group include monovalent groups of monocyclic hydrocarbon compounds such as benzene, diphenyl ether, polyethylene diphenyl ether, diphenyl thioether, and diphenyl sulfone, or biphenyl, polyphenyl, diphenylalkane, diphenylalkene, diphenylalkyne. , Monovalent groups of non-condensed polycyclic hydrocarbon compounds such as triphenylmethane, distyrylbenzene, 1,1-diphenylcycloalkane, polyphenylalkane, and polyphenylalkene, or rings such as 9,9-diphenylfluorene Examples thereof include monovalent groups of aggregated 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 a fluorine atom , 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 with an alkyl group or a C ₁ -C ₄ alkoxy group 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-ethoxy Examples include ethyl 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.
[6] The following general formula (c):

[In General Formula (c), R ₃ and R ₄ each independently represent a hydrogen atom, an alkyl group defined in [2] above, or an aryl group. Examples of the aryl group include a phenyl group, and a biphenyl group or a naphthyl group, which may contain an alkoxy group of C ₁ -C _4, alkyl group, or a halogen atom C ₁ -C ₄ as a substituent . R ₃ and R ₄ may form a ring together. ] Is represented.
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 such as a methylenedioxy group or a methylenedithio group, or an alkylenedithio group.
[8] Substituted or unsubstituted styryl group, substituted or unsubstituted β-phenylstyryl group, diphenylaminophenyl group, ditolylaminophenyl group and the like.

Examples of the arylene group represented by Ar ₁ and Ar ₂ include a divalent group derived from the aryl group represented by Ar ₃ and 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.

Examples of the substituted or unsubstituted alkylene group include C _{1 to} C ₁₂ , preferably C _{1 to} C ₈ , and more preferably C _{1 to} C ₄ linear or branched alkylene groups. a fluorine atom, a hydroxyl group, organic 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 You may do it.
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.

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

  As the vinylene group, the following general formula (d) or (e):

[In General Formula (d) or (e), R ₅ represents hydrogen, an alkyl group (the same as the alkyl group defined in [2] above), an aryl group (the aryl group represented by Ar ₃ or Ar ₄ above) The same), a represents 1 or 2, and b represents 1-3. ] Is represented.

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.

  Further, the polymerizable compound having a charge transporting structure of the present invention is more preferably a compound having a structure represented by the following general formula (3).

  [In general formula (3), o, p and q are each an integer of 0 or 1, Ra represents a hydrogen atom or a methyl group, Rb and Rc are substituents other than a hydrogen atom, and an alkyl group having 1 to 6 carbon atoms. And a plurality of cases may be different. s and t represent an integer of 0 to 3. Za represents a single bond, a methylene group, an ethylene group, or a divalent group represented by the following structural formulas (3-1), (3-2), or (3-3). ]

  As the compound represented by the general formula (3), compounds having a methyl group or an ethyl group are particularly preferable as substituents for Rb and Rc.

The charge transporting compound having a polymerizable functional group represented by the general formulas (1) and (2), particularly (3) used in the present invention is polymerized with the carbon-carbon double bond being released on both sides, so In a polymer that is incorporated into a chain polymer and crosslinked by polymerization with a polymerizable monomer that does not have a charge transporting structure, it is present in the main chain of the polymer, Present in the cross-linked chain between the main chain and the main chain (this cross-linked chain has an intermolecular cross-linked chain between one polymer and another polymer and a site where the main chain is folded in one polymer. And an intramolecular cross-linked chain that is cross-linked with another site derived from the polymerized monomer at a position away from the main chain).
Whether the charge transporting compound having a polymerizable functional group is present in the main chain or in the cross-linked chain, the triarylamine structure suspended from the chain portion is nitrogen It has at least three aryl groups arranged radially from the atoms 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. It is fixed in a flexible state. For this reason, these triarylamine structures can be arranged spatially adjacent to each other in the polymer with little structural distortion in the molecule, and when the surface layer of the electrophotographic photoreceptor is used, It is presumed that an intramolecular structure that is relatively free from interruption of the charge transport pathway can be taken.

  In the present invention, the specific acrylic ester compound represented by the following general formula (4) can also be used favorably as a charge transporting compound having a polymerizable functional group.

(In the general formula (4), Ar ₅ represents a monovalent or divalent group consisting of a substituted or unsubstituted aromatic hydrocarbon skeleton. Ar ₆ is an aromatic hydrocarbon having at least one tertiary amino group. B ₁ and B ₂ represent a monovalent group or divalent group consisting of a monovalent group or a divalent group consisting of a skeleton or a heterocyclic compound skeleton having at least one tertiary amino group, B ₁ and B ₂ are acryloyloxy groups, methacryloyloxy Represents an alkyl group having a group, a vinyl group, an acryloyloxy group or a methacryloyloxy group or a vinyl group, an acryloyloxy group, a methacryloyloxy group or an alkoxy group having a vinyl group.)

Examples of the substituted or unsubstituted aromatic hydrocarbon in Ar ₅ include benzene, naphthalene, phenanthrene, biphenyl, 1,2,3,4-tetrahydronaphthalene and the like. Examples of the substituent include an alkyl group having 1 to 12 carbon atoms, an alkoxy group having 1 to 12 carbon atoms, a benzyl group, and a halogen atom. The alkyl group and alkoxy group may further have a halogen atom or a phenyl group as a substituent.

Ar ₆ represents a monovalent group consisting of an aromatic hydrocarbon skeleton having at least one tertiary amino group, a monovalent group consisting of a divalent group or a heterocyclic compound skeleton having at least one tertiary amino group, or Although it represents a divalent group, the aromatic hydrocarbon skeleton having a tertiary amino group is represented by the following general formula (A).

(In general formula (A), R ₁₃ and R ₁₄ represent an acyl group, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aryl group. Ar ₇ represents an aryl group. W is an integer of 1 to 3. Represents.)

Examples of the acyl group for R ₁₃ and R ₁₄ include an acetyl group, a propionyl group, and a benzoyl group. The substituted or unsubstituted alkyl group for R ₁₃ and R ₁₄ is the same as the alkyl group described for the substituent for Ar ₅ . The substituted or unsubstituted aryl group for R ₁₃ and R ₁₄ is phenyl group, naphthyl group, biphenylyl group, terphenylyl group, pyrenyl group, fluorenyl group, 9,9-dimethyl-2-fluorenyl group, azulenyl group, anthryl group, In addition to the triphenylenyl group and the chrysenyl group, a group represented by the following general formula (B) can be exemplified.

[In the general formula (B) formula, B is -O -, - S -, - SO -, - SO 2 -, - CO- and the following general formula (B-1), represented by (B-2) Represents a divalent group. R ₂₁ represents a hydrogen atom, a substituted or unsubstituted alkyl group defined by Ar ₅ in formula (4), an alkoxy group, a halogen atom, a substituted or unsubstituted group defined by R ₁₃ in formula (A). An aryl group, an amino group, a nitro group, or a cyano group is represented. ]

[In General Formula (B-1) or (B-2), R ₂₂ represents a hydrogen atom, a substituted or unsubstituted alkyl group defined by Ar ₅ in General Formula (4), R in General Formula (A) ₁₃ represents a substituted or unsubstituted aryl group defined in ₁₃ , i represents an integer of 1 to 12, and j represents an integer of 1 to 3. )]

Specific examples of the alkoxy group for R ₂₁ include a methoxy group, an ethoxy group, an n-propoxy group,
i-propoxy group, n-butoxy group, i-butoxy group, s-butoxy group, t-butoxy group, 2-hydroxyethoxy group, 2-cyanoethoxy group, benzyloxy group, 4-methylbenzyloxy group, trifluoro A methoxy group etc. are mentioned.
Examples of the halogen atom for R ₂₁ include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.
Examples of the amino group of R ₂₁ include a diphenylamino group, a ditolylamino group, a dibenzylamino group, and a 4-methylbenzyl group.

As the aryl group of Ar _{7 in} the general formula (A), phenyl group, naphthyl group, biphenylyl group, terphenylyl group, pyrenyl group, fluorenyl group, 9,9-dimethyl-2-fluorenyl group, azulenyl group, anthryl group, triphenylenyl Group and chrysenyl group.
Ar ₇ , R ₁₃ and R ₁₄ in the general formula (A) may have an alkyl group, an alkoxy group or a halogen atom defined as Ar ₅ in the general formula (4) as a substituent.

Examples of the heterocyclic compound skeleton having a tertiary amino group include pyrrole, pyrazole, imidazole, triazole, dioxazole, indole, isoindole, benzimidazole, benzotriazole, benzisoxazine, carbazole, and phenoxazine. Examples include heterocyclic compounds having an amine structure. These may have an alkyl group, an alkoxy group, or a halogen atom defined by Ar ₅ in the general formula (4) as a substituent.
As described above, B ₁ and B ₂ are acryloyloxy group, methacryloyloxy group, vinyl group, acryloyloxy group, methacryloyloxy group, alkyl group having vinyl group, acryloyloxy group, methacryloyloxy group or alkoxy group having vinyl group. As the alkyl group and the alkoxy group, those described for Ar ₅ in the general formula (4) are similarly applied.

  As a more preferable structure in the acrylic ester compound of the general formula (4), a compound of the following general formula (5) can be exemplified.

[In the general formula (5), R ₈ and R ₉ represent a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxy group or a halogen atom, and Ar ₇ and Ar ₈ represent a substituted or unsubstituted aryl group. Or an arylene group and a substituted or unsubstituted benzyl group are represented. B _{1 to} B ₄ are the same as B ₁ and B ₂ in the general formula (4). u represents an integer of 0 to 5, and v represents an integer of 0 to 4. ]
The alkyl group, alkoxy group and halogen atom in R ₈ and R ₉ in the general formula (5) are the same as those described for Ar ₅ in the general formula (4). The aryl group in Ar ₇ and Ar ₈ is the same as the aryl group defined by R ₁₃ and R ₁₄ in formula (A). An arylene group is a divalent group derived from the aryl group.

The specific acrylic ester compound has the following characteristics.
It is a tertiary amine compound having a stilbene-type conjugated structure, and has a developed conjugated system. By using such a charge transporting compound with a conjugated system, the charge injection property at the interface portion of the cross-linked layer becomes very good, and intermolecular interaction is inhibited even when immobilized between cross-linked bonds. It is difficult and has good characteristics with respect to charge mobility. Further, it has a highly polymerizable acryloyloxy group or methacryloyloxy group in the molecule, and rapidly gels during polymerization and does not cause excessive crosslinking strain. The double bond of the stilbene structure in the molecule partially participates in the polymerization, and the polymerization is lower than the acryloyloxy group or methacryloyloxy group, resulting in a time difference in the crosslinking reaction, thereby maximizing the distortion. In addition, since the double bond in the molecule is used, the number of cross-linking reactions per molecular weight can be increased. As a result, the crosslink density can be increased, and further improvement in wear resistance can be realized. Moreover, this double bond can adjust a polymerization degree by bridge | crosslinking conditions, and can produce a cured resin layer easily (what is called formation of an optimal crosslinked film). Participation in the crosslinking polymerization reaction in the formation of such a crosslinked film is a specific feature of the acrylate compound and does not occur in the α-phenylstilbene type structure as described above.
From the above, the use of the charge transporting compound having a polymerizable functional group represented by the general formula (4), particularly the general formula (5), while maintaining good electrical characteristics and causing the occurrence of cracks and the like. Can form a film with extremely high crosslink density, thereby satisfying various characteristics of the photoconductor, preventing silica fine particles from sticking into the photoconductor, and reducing image defects such as white spots. it can.

  Specific examples of the polymerizable compound having a charge transporting structure used in the present invention are shown in Tables 1 to 12 below, but are not limited to the compounds having these structures.

  Further, the charge transporting compound having a polymerizable functional group used in the present invention is important for imparting the charge transport performance of the crosslinked surface layer, and this component is 80% by weight or less based on the total amount of the crosslinked surface layer, preferably The content of the coating liquid component is adjusted so as to be 70% by weight or less. When this component exceeds 80% by weight, the content of the polymerizable compound not having a charge transport structure is lowered, the crosslinking density is lowered, and high wear resistance is not exhibited. Although the electrical characteristics and abrasion resistance required differ depending on the process used, it cannot be said unconditionally. However, in consideration of the balance of both characteristics, the range of 70% by weight or less is most preferable.

In the formation of the surface protective layer constituting the electrophotographic photoreceptor of the present invention, a functional monomer is used for the purpose of imparting functions such as viscosity adjustment during coating, stress relaxation of the surface protective layer, reduction of surface energy and reduction of friction coefficient. In addition, a polymerizable oligomer can be used in combination.
Known functional monomers and polymerizable oligomers can be used. 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 polymerizable oligomer include epoxy acrylate, urethane acrylate, and polyester acrylate oligomers.
However, if a large amount of monofunctional and bifunctional functional polymerizable monomers or polymerizable oligomers having a low number of functional groups is contained, the three-dimensional cross-linking density of the surface protective layer consisting of a cross-linked structure is substantially reduced, resulting in wear resistance. Cause a decline. Therefore, the content of the functional polymerizable monomer or polymerizable oligomer is 50% by weight or less, preferably 30% by weight or less, based on the total amount of the crosslinked surface layer.

  In addition, the surface protective layer of the present invention comprises a supercritical fluid and / or a subcritical fluid containing an antioxidant in the crosslinked surface layer after forming a cured resin layer (crosslinked surface layer) by polymerizing a polymerizable compound. It is obtained by contacting, but if necessary, for the purpose of improving the reaction efficiency during this polymerization, a coating solution [for surface protective layer formation] used to form a crosslinked surface layer (for example, formed by a solution coating method) The coating liquid (surface protective layer coating liquid)] may contain a polymerization initiator. Conventionally known thermal polymerization initiators and photopolymerization initiators can be used favorably as the polymerization initiator.

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

  Examples of the photopolymerization initiator include diethoxyacetophenone, 2,2-dimethoxy-1,2-diphenylethane-1-one, 1-hydroxy-cyclohexyl-phenyl-ketone, 4- (2-hydroxyethoxy) phenyl- (2 -Hydroxy-2-propyl) ketone, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) butanone-1, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 2- Acetophenone-based or ketal-based photopolymerization initiators such as methyl-2-morpholino (4-methylthiophenyl) propan-1-one and 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, 1 Benzophenone photopolymerization initiators such as 2-benzoylbenzene, thioxanthones such as 2-isopropylthioxanthone, 2-chlorothioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, 2,4-dichlorothioxanthone As photopolymerization initiators and other photopolymerization initiators, ethyl anthraquinone, 2,4,6-trimethylbenzoyl diphenylphosphine oxide, 2,4,6-trimethylbenzoyl Phenylethoxyphosphine oxide, bis (2,4,6-trimethylbenzoyl) phenylphosphine oxide, bis (2,4-dimethoxybenzoyl) -2,4,4-trimethylpentylphosphine oxide, methylphenylglyoxyester, 9,10 -A phenanthrene, an acridine type compound, a triazine type compound, an imidazole type compound etc. are 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 polymerizability.

Furthermore, in the surface protective layer forming coating solution used for forming the cured resin layer in the present invention, various plasticizers (for example, for the purpose of stress relaxation and improvement in adhesiveness), a leveling agent, An additive such as a low-molecular charge transporting material having no polymerizability can be contained.
As these additives, known ones 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 a solid raw material of the coating liquid. It is suppressed to 20% by weight or less, preferably 10% by weight or less, based on the total amount (total solid content) of the composition. 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 surface protective layer in the electrophotographic photoreceptor of the present invention is obtained by applying and polymerizing a coating solution containing at least the above-described polymerizable compound on the photosensitive layer or the charge transport layer using the surface protective layer coating solution. In addition, when the polymerizable compound used in such a coating liquid is a liquid, it is formed by bringing a supercritical fluid and / or a subcritical fluid containing an antioxidant into contact with each other. It is also possible to apply after dissolving the components, and if necessary, it can be applied after diluting with a solvent.
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, and 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 coating liquid can be applied by dip coating, spray coating, bead coating, ring coating, or the like.

  In the present invention, after applying the coating liquid for the surface protective layer, energy is applied from the outside to polymerize the polymerizable compound to form a cured resin layer (crosslinked surface layer). Energy includes heat, light, and radiation.

  As a method for applying thermal energy, heating is performed from the coating surface side or the conductive support side using air, a gas such as nitrogen, steam, various heat media, infrared rays, or electromagnetic waves. The heating temperature is preferably 80 ° C. or more and 170 ° C. or less, and if it is less than 80 ° C., the reaction rate is slow and the reaction is not completely completed. At a temperature higher than 170 ° C., the reaction proceeds non-uniformly and a large strain is generated in the crosslinked surface layer. In order to advance the polymerization reaction uniformly, it is also effective to complete the reaction by heating at a relatively low temperature of less than 50 ° C. and then heating to 100 ° C. or more.

As the light energy, a UV irradiation light source such as a high-pressure mercury lamp or a metal halide lamp having an emission wavelength mainly in ultraviolet light can be used, but a visible light source can also be selected in accordance with the absorption wavelength of the polymerizable substance or the photopolymerization initiator. Is possible. Irradiation light amount is 50 mW / cm ² or more, preferably 500 mW / cm ² or more, more preferably 1000 mW / cm ² or more. By using irradiation light stronger than 1000 mW / cm ^2, the progress rate of the polymerization reaction is significantly increased, and a more uniform crosslinked surface layer can be formed. Examples of radiation energy include those using electron beams. Among these energies, those using heat and light energy are useful because of easy reaction rate control and simple apparatus.

Next, the image forming apparatus of the present invention will be described in detail with reference to the drawings.
The image forming apparatus of the present invention includes at least a charging unit for charging an electrophotographic photosensitive member, a latent image forming unit for forming an electrostatic latent image on the surface of the electrophotographic photosensitive member charged by the charging unit, and a latent image forming unit. Developing means for attaching toner to the electrostatic latent image formed by the transfer, transfer means for transferring the toner image formed by the developing means to the transfer target, and toner remaining on the surface of the electrophotographic photosensitive member after transfer And a cleaning means for removing from the surface of the photoreceptor.
The image forming method of the present invention is such that at least the electrophotographic photosensitive member produced by the production method of the present invention is charged by a charging unit, and electrostatically charged by the latent image forming unit on the surface of the electrophotographic photosensitive member charged by the charging unit. A latent image is formed, toner is attached to the electrostatic latent image formed by the latent image forming means by the developing means, the toner image formed by the developing means is transferred to the transfer medium by the transferring means, and electrophotography is performed after the transfer. The toner remaining on the surface of the photosensitive member is removed from the surface of the electrophotographic photosensitive member by a cleaning unit to form an image.
FIG. 4 is a schematic diagram for explaining the image forming process and the image forming apparatus of the present invention, and the following modifications also belong to the category of the present invention.

In FIG. 4, the photosensitive member 1 is formed by providing at least a photosensitive layer and a specific surface protective layer on a conductive support. The specific surface protective layer is obtained by polymerizing a polymerizable compound in advance to obtain a cured resin layer, and then contacting the cured resin layer with a supercritical fluid and / or a subcritical fluid containing at least one antioxidant. Is formed.
In FIG. 4, the photoconductor 1 has a drum shape, but may be a sheet shape or an endless belt shape. The charging roller 3 constituting the charging means, the pre-transfer charger 7, the transfer charger 10 constituting the transfer means, the separation charger 11, and the pre-cleaning charger 13 include corotron, scorotron, solid state charger (solid state charger), charging Known means such as a roller and a transfer roller are used. Reference numeral 12 denotes a separation claw.

  Of these charging methods, a contact charging method or a non-contact proximity arrangement method is particularly desirable. The contact charging method has merits such as high charging efficiency and a small amount of ozone generation, and miniaturization of the apparatus. The contact-type charging member referred to here is a type in which the surface of the charging member is in contact with the surface of the photosensitive member, and includes a charging roller, a charging blade, and a charging brush. Of these, charging rollers and charging brushes are used favorably.

  Further, the charging member arranged in the proximity is a type in which the charging member is arranged in a non-contact state so as to have a gap (gap) of 200 μm or less between the surface of the photoreceptor and the charging member surface. It is distinguished from known chargers typified by corotron and scorotron from the distance of the gap. The adjacently arranged charging member used in the present invention may have any shape as long as it has a mechanism capable of appropriately controlling the gap with the surface of the photoreceptor.

For example, the rotation shaft of the photosensitive member and the rotation shaft of the charging member may be mechanically fixed so as to have an appropriate gap. Among them, using a charging member in the shape of a charging roller, a gap forming member is disposed at both ends of the non-image forming portion of the charging member, and only this portion is brought into contact with the surface of the photoreceptor, and the image forming region is disposed in a non-contact manner. Alternatively, the gap forming member at both ends of the non-photosensitive portion of the photoconductor is disposed, and only this portion is brought into contact with the surface of the charging member, and the image forming region is disposed in a non-contact manner, so that the gap can be stably stabilized. It is a method that can be maintained. In particular, the methods described in JP-A Nos. 2002-148904 and 2002-148905 can be used satisfactorily. An example of the proximity charging mechanism in which the gap forming member is arranged on the charging member side is shown in FIG.
5, reference numeral 1 denotes a photosensitive member, 3 denotes a charging roller, 21 denotes a gap forming member, 22 denotes a metal shaft, 23 denotes an image forming area, and 24 denotes a non-image forming area.

  By adopting the above method, the charging efficiency is high and the amount of ozone generated is small, the device can be downsized, the toner is not contaminated, the mechanical wear due to contact is not generated, etc. It is used well because of its advantages. Furthermore, as an application method of voltage, the use of AC superposition can be used satisfactorily because there is an advantage that uneven charging is less likely to occur.

  When such a contact type charging member or a non-contact charging type charging member is used, there is a drawback that dielectric breakdown of the photosensitive member is likely to occur. However, the photoreceptor used in the image forming apparatus of the present invention can have an intermediate layer composed of a laminate structure of a charge blocking layer and a moire preventing layer, and the photosensitive layer contains coarse particles of a charge generating material. Therefore, the pressure resistance of the photoreceptor is extremely high. For this reason, the resistance against the dielectric breakdown of the photosensitive member is high, and the merit (prevention of uneven charging) of the charging member can be utilized.

  Although the photosensitive member is charged by the charging member that constitutes such a charging unit, in an ordinary image forming apparatus, since the background is easily soiled due to the photosensitive member, the electric field strength applied to the photosensitive member is low. (40 V / μm or less, preferably 30 V / μm or less). This is because the occurrence of soiling depends on the electric field strength, and the probability of soiling increases as the electric field strength increases.

However, reducing the electric field strength applied to the photoreceptor reduces the efficiency of photocarrier generation and reduces the photosensitivity. In addition, since the electric field strength applied between the surface of the photosensitive member and the conductive support is reduced, the straightness of the photocarrier generated in the photosensitive layer is reduced, and diffusion due to clone repulsion is increased, resulting in a reduction in resolution. Arise.
On the other hand, by using the electrophotographic photosensitive member of the present invention, it is possible to extremely reduce the probability of occurrence of background contamination. Therefore, it is not necessary to reduce the electric field strength more than necessary, and it can be used even under an electric field strength of 40 V / μm or more. For this reason, a sufficient amount of gain in the attenuation of the photoreceptor light can be secured, a large margin can be created for the later-described development (potential), and development can be performed without reducing the resolution.

The image exposure unit 5 constituting the latent image forming unit uses a light source capable of ensuring high luminance such as a light emitting diode (LED), a semiconductor laser (LD), and electroluminescence (EL).
As a light source such as the static elimination lamp 2, general light emitting materials such as a fluorescent lamp, a tungsten lamp, a halogen lamp, a mercury lamp, a sodium lamp, a light emitting diode (LED), a semiconductor laser (LD), and an electroluminescence (EL) can be used. . Various types of filters such as a sharp cut filter, a band pass filter, a near infrared cut filter, a dichroic filter, an interference filter, and a color temperature conversion filter can be used to irradiate only light in a desired wavelength range.

  Among these light sources, light emitting diodes and semiconductor lasers have high irradiation energy and long wavelength light of 600 to 800 nm, so that the above-mentioned phthalocyanine pigment, which is a charge generation material, exhibits high sensitivity and is used well. The 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.

  In FIG. 4, the toner developed on the photosensitive member 1 by the developing unit 6 constituting the developing means is transferred to the transfer paper 9 by the separation charger 11 constituting the transfer means, but not all is transferred. Also, toner remaining on the photoreceptor 1 is generated. Such toner is removed from the photosensitive member by a cleaning brush (fur brush) 14 and a cleaning blade 15 constituting a cleaning unit. 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. Reference numeral 8 denotes a registration roller.

  When a positive (negative) charge is applied to the electrophotographic photosensitive member and image exposure is performed, a positive (negative) electrostatic latent image is formed on the surface of the photosensitive member. If this is developed with toner of negative (positive) polarity (detection fine particles), a positive image can be obtained, and if developed with toner of positive (negative) polarity, a negative image can be obtained. A known method is applied to the developing unit, and a known method is also used for the charge eliminating unit.

The schematic diagram of FIG. 6 shows another example of the image forming apparatus configuration and the image forming process in the present invention. In FIG. 6, the photosensitive member 21 is provided with at least a photosensitive layer and the specific surface protective layer described above on a conductive support. An image exposure source 24 that constitutes a latent image forming means, which is driven by driving rollers 22a and 22b and is charged by a charging charger 23 constituting a charging means.
Image exposure by the developing means, development by the developing means (not shown), transfer using the transfer charger (charger) 25 constituting the transferring means, exposure before cleaning by the exposure light source 26 before cleaning, and cleaning by the cleaning brush 27 constituting the cleaning means. The static elimination by the static elimination light source 28 is repeated.

  The above illustrated electrophotographic process is illustrative of an embodiment of the present invention, and of course other embodiments are possible. For example, in FIG. 6, the pre-cleaning exposure is performed from the support side, but this may be performed from the photosensitive layer side, or irradiation with static elimination light may be performed from the support side.

  On the other hand, in the light irradiation process, image exposure, pre-cleaning exposure, and static elimination exposure are illustrated, but other pre-exposure exposure, pre-exposure of image exposure, and other known light irradiation processes are provided to light the photosensitive member. Irradiation can also be performed.

The image forming means as described above may be fixedly incorporated in a copying apparatus, a facsimile, or a printer, but may be incorporated in these apparatuses in the form of a process cartridge. A process cartridge is a single device (part) that contains a photosensitive member, and further includes a charging unit, an exposure unit (latent image forming unit), a developing unit, a transfer unit, a cleaning unit, and a charge eliminating unit. There are many shapes and the like of the process cartridge, but a general configuration example includes the one shown in the schematic diagram of FIG. The photoreceptor 1 is formed by providing at least a photosensitive layer and the specific surface protective layer described above on a conductive support.
In the figure, reference numeral 1 denotes a photosensitive member, reference numeral 3 denotes a charging roller constituting a charging means, reference numeral 5 denotes an image exposure unit constituting a latent image forming means, reference numeral 15 denotes a cleaning brush constituting a cleaning means, and reference numeral 16 denotes a cleaning brush. A developing roller constituting the developing means, and a reference numeral 17 denotes a transfer roller constituting the transferring means.

  FIG. 8 is a schematic view for explaining another example (tandem type full-color electrophotographic apparatus) of the image forming apparatus according to 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 denote drum-shaped photoconductors. The photoconductor 1 is formed by providing at least a photoconductive layer and the specific surface protective layer described above on a conductive support.

  The photoconductors 1C, 1M, 1Y, and 1K rotate in the direction of the arrow in the figure, and charging members 2C, 2M, 2Y, and 2K constituting charging means at least in the order of rotation around the photosensitive members 1C, 1M, 1Y, and 1K, and developing members 4C and 4M, 4Y, 4K and cleaning members 5C, 5M, 5Y, 5K constituting the cleaning means are arranged. The charging members 2C, 2M, 2Y, and 2K are charging members that constitute a charging device for uniformly charging the surface of the photoreceptor. Laser light 3C, 3M, 3Y, and the like from an exposure member constituting a latent image forming means (not shown) from the photosensitive member surface side between the charging members 2C, 2M, 2Y, 2K and the developing members 4C, 4M, 4Y, 4K. 3K is irradiated, and electrostatic latent images are formed on the photoreceptors 1C, 1M, 1Y, and 1K.

  Then, four image forming elements 6C, 6M, 6Y, and 6K centering on such photoreceptors 1C, 1M, 1Y, and 1K are juxtaposed along a transfer conveyance belt 10 that is a transfer material conveyance unit. The transfer conveyance belt 10 contacts the photoreceptors 1C, 1M, 1Y, and 1K between the developing members 4C, 4M, 4Y, and 4K of the image forming units 6C, 6M, 6Y, and 6K and the cleaning members 5C, 5M, 5Y, and 5K. Transfer brushes 11C, 11M, 11Y, and 11K constituting transfer means for applying a transfer bias are disposed on the surface (back surface) that is in contact with and contacts the back side of the photoconductor side of the transfer conveyance belt 10. 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 color electrophotographic 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 photoreceptors 1C, 1M, 1Y, and 1K are charged by the charging members 2C, 2M, 2Y, and 2K that rotate in the direction of the arrow (the direction along with the photoreceptor). Next, an electrostatic latent image corresponding to each color image to be created is formed by the laser beams 3C, 3M, 3Y, and 3K at the exposure unit constituting the latent image forming means (not shown) disposed outside the photoconductor. Is done. Next, the latent image is developed by developing members 4C, 4M, 4Y, and 4K to form a toner image.

The developing members 4C, 4M, 4Y, and 4K are developing members that perform development with toners of C (cyan), M (magenta), Y (yellow), and K (black), respectively, and the four photosensitive members 1C, 1M, and 1Y. , 1K toner images of each color are superimposed on the transfer paper.
The transfer paper 7 is sent out from the tray by a paper feed roller 8, temporarily stopped by a pair of registration rollers 9, and sent to the transfer conveyance belt 10 in synchronism with the image formation on the photosensitive member.
The transfer paper 7 held on the transfer conveyance belt 10 is conveyed, and the toner images of each color are transferred at the contact positions (transfer portions) with the photoconductors 1C, 1M, 1Y, 1K.

The toner image on the photoconductor is transferred onto the transfer paper 7 by an electric field formed from a potential difference between the transfer bias applied to the transfer brushes 11C, 11M, 11Y, and 11K and the photoconductors 1C, 1M, 1Y, and 1K. The Then, the recording paper 7 on which the four color toner images are superimposed through the four transfer portions is conveyed to a fixing device 12 as fixing means, where the toner is fixed, and is discharged to a paper discharge portion (not shown).
Further, the residual toner remaining on the photoreceptors 1C, 1M, 1Y, and 1K without being transferred at the transfer portion is
It is collected by cleaning members (cleaning devices) 5C, 5M, 5Y, 5K constituting the cleaning means.
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, it is not limited to this order, and the color order is arbitrarily set. Further, when a black-only document is created, it is particularly effective to use the present invention to provide a mechanism for stopping the image forming elements (6C, 6M, 6Y) other than black.
Further, in FIG. 8, the charging member is in contact with the photoreceptor, but by using a charging mechanism as shown in FIG. 5, by providing an appropriate gap (about 10-200 μm) between them, Both wear amounts can be reduced, and toner filming on the charging member can be reduced and the toner can be used satisfactorily.

  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. As described above, the process cartridge is a single device (part) that contains a photosensitive member, and further includes a charging unit, an exposure unit (latent image forming unit), a developing unit, a transfer unit, a cleaning unit, a neutralizing unit, and the like. It is.

Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples.
First, synthesis examples of the compound having a charge transporting structure used in the present invention are shown. The compound having a charge transporting 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.

<Synthesis Example of Polymerizable Compound Having Charge Transporting Structure>
(1) Synthesis of hydroxy group-substituted triarylamine compound [the following structural formula (g)]:
240 ml of sulfolane was added to 113.85 g (0.3 mol) of a methoxy group-substituted triarylamine compound [the following structural formula (f)] and 138 g (0.92 mol) of sodium iodide, and the mixture was heated to 60 ° C. in a nitrogen stream. . In this liquid, 99 g (0.91 mol) of trimethylchlorosilane was added dropwise over 1 hour and stirred at a temperature of about 60 ° C. for 4 and a half hours to complete the reaction.
About 1.5 L 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.
As a result, 88.1 g (yield = 80.4%) of white crystals of a hydroxy group-substituted triarylamine compound represented by the following structural formula (g) was obtained. The melting point of the obtained compound was 64.0 to 66.0 ° C., and the elemental analysis results agreed well with the calculated values as shown in Table 13 below.

(2) Synthesis of Triarylamino Group-Substituted Acrylate Compound (Exemplary Compound No. 54 in Table 3) Hydroxy Group-Substituted Triarylamine Compound [Structural Formula (g)] Obtained in (1) above 82.9 g (0 .227 mol) was dissolved in 400 ml of tetrahydrofuran, and an aqueous sodium hydroxide solution (NaOH: 12.4 g, water: 100 ml) was added dropwise in a nitrogen stream. The solution was cooled to 5 ° C., and 25.2 g (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, 80.73 g (yield = 84.8%) of white crystals of a triarylamino group-substituted acrylate compound (Exemplary Compound No. 54) was obtained. The melting point of the obtained compound was 117.5 to 119.0 ° C., and the results of elemental analysis agreed well with the calculated values as shown in Table 14 below.

(3) Synthesis example of acrylic ester compound <Preparation of diethyl 2-hydroxybenzylphosphonate>
Into a reaction vessel equipped with a stirrer, thermometer, and dropping funnel, 38.4 g of 2-hydroxybenzyl alcohol (manufactured by Tokyo Chemical Industry) and 80 ml of o-xylene are placed, and triethyl phosphite (manufactured by Tokyo Chemical Industry Co., Ltd.) in a nitrogen stream. 62.8 g was slowly added dropwise at 80 ° C., and the reaction was further carried out at the same temperature for 1 hour. Thereafter, the produced ethanol, the solvent o-xylene, and unreacted triethyl phosphite were removed by distillation under reduced pressure to obtain 66 g of diethyl 2-hydroxybenzylphosphonate (yield 90%). The boiling point of the obtained diethyl 2-hydroxybenzylphosphonate was 120.0 ° C./1.5 mmHg.
<Preparation of 2-hydroxy-4 '-(N, N-bis (4-methylphenyl) amino) stilbene>
Into a reaction vessel equipped with a stirrer, a thermometer, and a dropping funnel, 14.8 g of potassium tert-butoxide and 50 ml of tetrahydrofuran were placed. Under a nitrogen stream, 9.90 g of diethyl 2-hydroxybenzylphosphonate and 4- (N, N A solution in which 5.44 g of -bis (4-methylphenyl) amino) benzaldehyde was dissolved in tetrahydrofuran was slowly added dropwise at room temperature, and then reacted at the same temperature for 2 hours. Thereafter, water was added under water cooling, and then 2N hydrochloric acid aqueous solution was added for acidification. Tetrahydrofuran was removed by an evaporator, and the crude product was extracted with toluene. The toluene phase was washed with water, an aqueous sodium hydrogen carbonate solution and saturated brine in this order, and dehydrated by adding magnesium sulfate. After filtration, toluene was removed to obtain an oily crude product, which was further purified with silica gel and then crystallized in hexane to give 5.09 g of 2-hydroxy-4 ′-(N, N-bis). (4-Methylphenyl) amino) stilbene was obtained (yield 72%). The melting point of the obtained stilbene compound was 36.0 to 138.0 ° C.
<Preparation of 4 '-(N, N-bis (4-methylphenyl) amino) stilben-2-yl acrylate>
In a reaction vessel equipped with a stirrer, a thermometer, and a dropping funnel, 14.9 g of 2-hydroxy-4 ′-(N, N-bis (4-methylphenyl) amino) stilbene, 100 ml of tetrahydrofuran, 12% concentration of hydroxide 21.5 g of an aqueous sodium solution was added, and 5.17 g of acrylic acid chloride was added dropwise over 5 minutes at 5 ° C. under a nitrogen stream. Then, it was made to react at the same temperature for 3 hours. The reaction solution was poured into water, extracted with toluene, concentrated and subjected to column purification with silica gel. The obtained crude product was recrystallized from ethanol, and yellow needle-like 4 ′-(N, N-bis (4-methylphenyl) amino) stilben-2-yl acrylate (Exemplary Compound NO105 in Table 6) 13 0.5 g was obtained (yield 79.8%). Melting point of Example Compound NO105 obtained was 104.1-105.2 ° C., and the elemental analysis results were in good agreement with the calculated values as shown in Table 15 below.

  As described above, a number of 2-hydroxystilbene derivatives are synthesized by reacting 2-hydroxybenzylphosphonic acid ester derivatives with various amino-substituted benzaldehyde derivatives. An ester compound can be synthesized.

Hereinafter, although an example is given and the present invention is explained, the present invention is not restricted by these examples. All parts are parts by weight.

[Example 1]
After coating on an aluminum cylinder (JIS 1050) having a length of 340 mm and a diameter of 30 mm using an intermediate layer coating solution having the following composition, drying was performed at 130 ° C. for 20 minutes to form an intermediate layer of about 3.5 μm. Subsequently, after coating using a coating solution for charge generation layer having the following composition, drying was performed at 130 ° C./20 minutes to form a charge generation layer of about 0.2 μm. Furthermore, after coating using a coating solution for a charge transport layer having the following composition, drying was performed at 130 ° C. for 20 minutes to form a charge transport layer having a thickness of about 20 μm. In all cases, the blade coating method was used.

(Intermediate layer coating solution)
Titanium oxide CR-EL (manufactured by Ishihara Sangyo Co., Ltd.): 50 parts Alkyd resin Beckolite M6401-50 (solid content 50% by weight,
Dainippon Ink & Chemicals, Inc.): 15 parts Melamine resin L-145-60 (solid content 60% by weight,
Dainippon Ink & Chemicals, Inc.): 8 parts 2-butanone: 120 parts

(Coating solution for charge generation layer)
Asymmetric bisazo pigment represented by the following structural formula (h): 2.5 parts Polyvinyl butyral ("XYHL" manufactured by UCC): 0.5 parts Methyl ethyl ketone: 110 parts Cyclohexanone: 260 parts

(Coating liquid for charge transport layer)
Polycarbonate Z Polyca (manufactured by Teijin Chemicals): 10 parts Charge transporting compound represented by the following structural formula (i): 7 parts Tetrahydrofuran: 80 parts Silicone oil (KF50-100cs, manufactured by Shin-Etsu Chemical Co., Ltd.): 0.002 parts

  The photoconductor obtained as described above was photocured with a coating solution for a crosslinked surface layer having the following composition using a Ushio UV lamp system with a UV irradiation time of 90 seconds, and further dried at 70 ° C./20 minutes. To provide a cross-linked surface layer of about 7 μm.

(Coating liquid for crosslinked surface layer)
Radical polymerizable compound: KAYARAD TMPTA (manufactured by Nippon Kayaku, trifunctional): 10 parts Polymerization initiator: Irgacure 184 (manufactured by Ciba Specialty Chemicals): 1 part Tetrahydrofuran: 50 parts

  A photoreceptor obtained as described above, and 0.6 parts of Sumilizer 9A (manufactured by Sumitomo Chemical Co., Ltd., an amine-based antioxidant) as an antioxidant and 30 parts of a charge transporting compound represented by the following structural formula (j) The container was accommodated in a pressure-resistant vessel having an internal volume of 700 mL, carbon dioxide was selected as the supercritical fluid, and the treatment was performed by the circulation method under the following conditions.

  Heating and pressurization were performed at room temperature and 0.10 MPa at a heating rate of 2-3 ° C./min and a pressurization rate of 0.2 MPa / min to 40 ° C. and 7 MPa. Here, with a flow rate of 5.0 L / min (standard value conversion value), heating and pressurization are performed at a heating rate of 2 to 3 ° C./min and a pressurization rate of 10 MPa / min. Supercritical fluid. The treatment was performed for 2 hours while maintaining the flow rate at 5.0 L / min (standard state converted value). Thereafter, the flow rate is set to 1.0 to 3.0 L / min (converted to the standard state), and the pressure is reduced by cooling at a cooling rate of 2 to 3 ° C./min and a depressurization rate of 3 to 5 MPa / min. It returned to (1 atmosphere). As described above, the electrophotographic photosensitive member of Example 1 was obtained.

[Example 2]
The electrophotographic photosensitive member of Example 2 is the same as Example 1 except that the antioxidant and the charge transporting compound added in the step of contacting the supercritical fluid and / or subcritical fluid of Example 1 are changed as follows. Got the body.
〔Antioxidant〕
Sumilizer 9A (Sumitomo Chemical, amine-based antioxidant): 0.3 part Antigene 6C (Sumitomo Chemical, amine-based antioxidant): 0.3 part [Charge transporting compound represented by the following structural formula (k) ]

[Example 3]
The polymerization initiator of the coating liquid for the crosslinked surface layer of Example 1 was changed to Irgacure 784 (manufactured by Ciba Specialty Chemicals), and the antioxidant added in the step of contacting the supercritical fluid and / or subcritical fluid and An electrophotographic photoreceptor of Example 3 was obtained in the same manner as in Example 1 except that the charge transporting compound was changed as follows.
〔Antioxidant〕
Sumilizer 224-S (manufactured by Sumitomo Chemical Co., Ltd., amine-based antioxidant): 0.3 part ADK STAB PEP-24 (manufactured by Asahi Denka Kogyo Co., Ltd., phosphorus-based antioxidant): 0.3 part [shown by the following structural formula (i) Charge transporting compound)

[Example 4]
The radical polymerizable compound of the coating liquid for the crosslinked surface layer of Example 1 was changed to ABE-300 (manufactured by Shin-Nakamura Chemical Co., Ltd., bifunctional), and the polymerization initiator was changed to 2-chlorothioxanthone (manufactured by Tokyo Chemical Industry Co., Ltd.). And / or the electrophotographic photoreceptor of Example 4 was obtained in the same manner as in Example 1 except that the antioxidant and the charge transporting compound added in the step of contacting the subcritical fluid were changed as follows.
〔Antioxidant〕
2,6-di-t-butyl-p-cresol (manufactured by Tokyo Chemical Industry, phenolic antioxidant): 0.6 parts [charge transporting compound represented by the following structural formula (m)]

[Example 5]
The radical polymerizable compound of the coating solution for the crosslinked surface layer of Example 1 was changed to U-15HA (manufactured by Shin-Nakamura Chemical Co., Ltd., 15 functional), and the polymerization initiator was changed to Irgacure 907 (manufactured by Ciba Specialty Chemicals) to be supercritical. An electrophotographic photosensitive member of Example 5 was obtained in the same manner as in Example 1 except that the antioxidant and the charge transporting compound added in the step of contacting the fluid and / or the subcritical fluid were changed as follows.
〔Antioxidant〕
Irgafos 168 (Ciba Specialty Chemicals,
Phosphorous antioxidant): 0.6 part [Charge transporting compound represented by the following structural formula (n)]

[Example 6]
The radical polymerizable compound of the coating solution for the crosslinked surface layer of Example 1 was changed to SR-295 (manufactured by Kayaku Sartomer, tetrafunctional), and the polymerization initiator was changed to Darocur 1173 (manufactured by Ciba Specialty Chemicals). An electrophotographic photoreceptor of Example 6 was obtained in the same manner as in Example 1 except that the antioxidant and the charge transporting compound added in the step of contacting the fluid and / or the subcritical fluid were changed as follows.
〔Antioxidant〕
Sumilizer GA-80 (manufactured by Sumitomo Chemical Co., Ltd., phenolic antioxidant): 0.6 parts [Charge transporting compound represented by the following structural formula (o)]

[Example 7]
The radical polymerizable compound of the coating solution for the crosslinked surface layer of Example 3 was changed to KAYARAD DPHA (made by Nippon Kayaku Co., Ltd., 5.5 functional), and the polymerization initiator was changed to 2,4-diethylthioxanthone (made by Tokyo Chemical Industry), An electrophotographic photoreceptor of Example 7 was obtained in the same manner as in Example 3 except that the antioxidant added in the step of contacting the supercritical fluid and / or subcritical fluid was changed as follows.
〔Antioxidant〕
Sanol LS-2626 (manufactured by Sankyo, amine antioxidant): 0.3 part ADK STAB HP-10 (manufactured by Asahi Denka Kogyo, phosphorus antioxidant): 0.3 part

[Example 8]
The intermediate layer in Example 3 has a stacked structure of a charge blocking layer and a moire preventing layer, and a 0.5 μm charge blocking layer and a 3.5 μm moire preventing layer are provided using a coating liquid having the following composition to form a crosslinked surface layer The polymerizable compound of the coating liquid for use is changed to KAYARAD DPCA-120 (Nippon Kayaku, 6-functional), and the polymerization initiator is changed to phenylbis (2,4,6-trimethylbenzoyl) phosphine oxide (manufactured by Tokyo Kasei). An electrophotographic photoreceptor of Example 8 was obtained in the same manner as in Example 3 except that the antioxidant added in the step of contacting the supercritical fluid and / or subcritical fluid was changed as follows.

(Charge blocking layer coating solution)
N-methoxymethylated nylon (manufactured by Lead City, FR101): 5 parts Methanol: 70 parts n-Butanol: 30 parts (Moire prevention layer coating solution)
Titanium oxide (Ishihara Sangyo Co., Ltd., CR-EL): 126 parts Alkyd resin (Dainippon Ink & Chemicals,
Beckolite M6401-50-S): 33.6 parts Melamine resin (Dainippon Ink Chemical Co., Ltd.,
Super Becamine L-121-60): 18.7 parts 2-butanone: 100 parts [Antioxidant]
2,6-di-t-butyl-p-cresol (manufactured by Tokyo Chemical Industry, phenolic antioxidant): 0.3 part ADK STAB 2112 (manufactured by Asahi Denka Kogyo, phosphorus antioxidant): 0.3 part

[Example 9]
The polymerizable compound of the coating solution for the crosslinked surface layer of Example 8 was changed to KAYARAD TMPTA (manufactured by Nippon Kayaku Co., Ltd., trifunctional), and the polymerization initiator was changed to Irgacure 184 (manufactured by Ciba Specialty Chemicals). An electrophotographic photosensitive member of Example 9 was obtained in the same manner as in Example 8 except that the antioxidant added in the step of contacting the subcritical fluid was changed as follows.
〔Antioxidant〕
Irganox 1076 (Ciba Specialty Chemicals,
Phenolic antioxidant): 0.3 part Irgafos 168 (manufactured by Ciba Specialty Chemicals)
Phosphorous antioxidant): 0.3 part

[Example 10]
The polymerization initiator of the coating solution for the crosslinked surface layer of Example 3 was changed to Irgacure 184 (manufactured by Ciba Specialty Chemicals), and an antioxidant added in the step of contacting the supercritical fluid and / or subcritical fluid was added. An electrophotographic photosensitive member of Example 10 was obtained in the same manner as Example 3 except for the following changes.
〔Antioxidant〕
Irganox 245 (Ciba Specialty Chemicals,
Phenolic antioxidant): 0.3 part ADK STAB HP-10 (manufactured by Asahi Denka Kogyo, phosphorus antioxidant): 0.3 part

[Example 11]
An electrophotographic photoreceptor of Example 11 was obtained in the same manner as in Example 10 except that the antioxidant added in the step of contacting the supercritical fluid and / or subcritical fluid of Example 10 was changed as follows.
〔Antioxidant〕
Irganox 1035 (Ciba Specialty Chemicals,
Phenol-based antioxidant): 0.3 part ADK STAB PEP-24 (Asahi Denka Kogyo, phosphorus-based antioxidant): 0.3 part

[Example 12]
Except that the antioxidant added in the step of contacting the supercritical fluid and / or subcritical fluid in Example 9 was changed to only 0.6 parts of Irganox 1076 (manufactured by Ciba Specialty Chemicals, phenolic antioxidant). In the same manner as in Example 9, an electrophotographic photoreceptor of Example 12 was obtained.

[Example 13]
Except that the antioxidant added in the step of contacting the supercritical fluid and / or subcritical fluid in Example 10 was changed to only 0.6 parts of Irganox 245 (manufactured by Ciba Specialty Chemicals, phenolic antioxidant). The electrophotographic photoreceptor of Example 13 was obtained in the same manner as Example 10.

[Example 14]
Except that the antioxidant added in the step of contacting the supercritical fluid and / or subcritical fluid in Example 11 was changed to only 0.6 parts of Irganox 1035 (manufactured by Ciba Specialty Chemicals, phenolic antioxidant). The electrophotographic photoreceptor of Example 14 was obtained in the same manner as Example 11.

[Example 15]
An electrophotographic photoreceptor of Example 15 was obtained in the same manner as in Example 8, except that a mixture of carbon dioxide and methanol was selected as the supercritical fluid in the step of contacting the supercritical fluid and / or subcritical fluid of Example 8. .

[Example 16]
An electrophotographic photoreceptor of Example 16 was obtained in the same manner as in Example 8, except that a mixture of carbon dioxide and ethanol was selected as the supercritical fluid in the step of contacting the supercritical fluid and / or subcritical fluid of Example 8. .

[Example 17]
The electrophotographic photoreceptor of Example 17 is the same as Example 8 except that the amount of the antioxidant added in the step of contacting the supercritical fluid and / or subcritical fluid of Example 8 is 0.5 parts each. Got.

[Example 18]
The electrophotographic photoreceptor of Example 18 is the same as Example 8 except that the amount of the antioxidant added in the step of contacting the supercritical fluid and / or subcritical fluid of Example 8 is 0.8 parts each. Got.

[Example 19]
The electrophotographic photosensitive member of Example 19 is the same as Example 8 except that the amount of the antioxidant added in the step of contacting the supercritical fluid and / or subcritical fluid of Example 8 is 1.0 part each. Got.

[Example 20]
An electrophotographic photoreceptor of Example 20 was obtained in the same manner as in Example 8, except that the temperature maintained in the step of contacting the supercritical fluid and / or subcritical fluid of Example 8 was changed from 90 ° C. to 30 ° C.

[Example 21]
An electrophotographic photosensitive member of Example 21 was obtained in the same manner as in Example 8, except that the temperature maintained in the step of contacting the supercritical fluid and / or subcritical fluid of Example 8 was changed from 90 ° C. to 60 ° C.

[Example 22]
An electrophotographic photoreceptor of Example 22 was obtained in the same manner as in Example 8, except that the temperature maintained in the step of contacting the supercritical fluid and / or subcritical fluid of Example 8 was changed from 90 ° C. to 120 ° C.

[Example 23]
An electrophotographic photoreceptor of Example 23 was obtained in the same manner as in Example 8, except that the temperature maintained in the step of contacting the supercritical fluid and / or subcritical fluid of Example 8 was changed from 90 ° C. to 140 ° C.

[Example 24]
Example except that 10 parts of a polymerizable compound having the charge transporting structure represented by the following structural formula (p) (Exemplary Compound No .: NO. 54) in Table 3 was added to the coating solution for the crosslinked surface layer of Example 9. In the same manner as in Example 9, an electrophotographic photoreceptor of Example 24 was obtained.

[Example 25]
Example 9 except that 10 parts of a polymerizable compound having a charge transporting structure represented by the following structural formula (q) (Exemplary compound number: No. 105 in Table 6) was added to the coating solution for a crosslinked surface layer of Example 9. In the same manner as described above, an electrophotographic photosensitive member of Example 25 was obtained.

[Example 26]
Example 10 except that 10 parts of a polymerizable compound having a charge transporting structure represented by the following structural formula (r) (Exemplary compound number: NO. 180 in Table 12) was added to the crosslinked surface layer coating solution of Example 9. As in Example 9, an electrophotographic photoreceptor of Example 26 was obtained.

[Example 27]
The electrophotographic photosensitive member of Example 27 was obtained in the same manner as in Example 24 except that the charge transporting compound added in the step of contacting the supercritical fluid and / or subcritical fluid of Example 24 was changed to 0 part.

[Example 28]
The electrophotographic photosensitive member of Example 28 was obtained in the same manner as in Example 25 except that the charge transporting compound added in the step of contacting the supercritical fluid and / or subcritical fluid of Example 25 was changed to 0 part.

[Example 29]
The electrophotographic photosensitive member of Example 29 was obtained in the same manner as in Example 26 except that the charge transporting compound added in the step of contacting the supercritical fluid and / or subcritical fluid of Example 26 was changed to 0 part.

[Example 30]
The coating solution for the crosslinked surface layer of Example 1 was changed as follows, and was the same as Example 1 except that UV irradiation was not performed and 130 ° C./30 minutes of heat drying was performed to provide a crosslinked surface layer of about 7 μm. An electrophotographic photosensitive member of Example 30 was obtained.
(Coating liquid for crosslinked surface layer)
Polymerizable compound: KAYARAD TMPTA (manufactured by Nippon Kayaku, trifunctional): 10 parts Polymerization initiator: Parkardx 12-EB (thermal polymerization initiator manufactured by Kayaku Akzo): 1 part Tetrahydrofuran: 50 parts

[Comparative Example 1]
In Example 1, the electrophotographic photosensitive member of Comparative Example 1 was obtained without providing the cross-linked surface layer and setting the charge transport layer to 35 μm.

[Comparative Example 2]
An electrophotographic photoreceptor of Comparative Example 2 was obtained in the same manner as in Example 1 except that the step of contacting the supercritical fluid and / or subcritical fluid in Example 1 was omitted.

[Comparative Example 3]
The electrophotographic photosensitive member of Comparative Example 3 was obtained in the same manner as in Example 1 except that the antioxidant added in the step of contacting the supercritical fluid and / or subcritical fluid of Example 1 was changed to 0 part. .

[Comparative Example 4]
An electrophotographic photosensitive member of Comparative Example 4 was obtained in the same manner as in Example 24 except that the antioxidant added in the step of contacting the supercritical fluid and / or subcritical fluid of Example 24 was changed to 0 part. .

[Comparative Example 5]
An electrophotographic photosensitive member of Comparative Example 5 is obtained in the same manner as Comparative Example 2 except that the coating solution for the crosslinked surface layer of Comparative Example 2 is changed as follows in accordance with Example 5 of JP-A-2006-99028. It was.
(Coating liquid for crosslinked surface layer)
Polymerizable compound: KAYARAD TMPTA (manufactured by Nippon Kayaku, trifunctional): 5 parts Polymerizable compound: KAYARAD DPHA (manufactured by Nippon Kayaku, 5.5 functional): 5 parts Polymerizable compound having a charge transporting structure (exemplary compound) Number: NO. 54): 10 parts Polymerization initiator: Irgacure 184 (manufactured by Ciba Specialty Chemicals): 1 part Tetrahydrofuran (2,6-di-t-butyl-p-cresol, containing 0.02 part): 80 Part Sumilizer BP-76 (manufactured by Sumitomo Chemical, phenolic antioxidant): 0.5 part

[Comparative Example 6]
An electrophotographic photosensitive member of Comparative Example 6 was obtained in the same manner as Comparative Example 2 except that the coating solution for the crosslinked surface layer of Comparative Example 2 was changed as follows in accordance with Example 1 of JP-A-2006-11014. It was.
(Coating liquid for crosslinked surface layer)
Polymerizable compound: KAYARAD TMPTA (manufactured by Nippon Kayaku Co., Ltd., trifunctional): 10 parts Polymerizable compound having a charge transporting structure (exemplary compound number: NO. 54): 10 parts Polymerization initiator: Irgacure 184 (Ciba Specialty) Chemicals): 2 parts Tetrahydrofuran: 100 parts Sumilizer GM (manufactured by Sumitomo Chemical, bifunctional phenolic antioxidant): 2 parts

<NOx gas exposure assessment>
The electrophotographic photosensitive members produced in Examples 1 to 30 and Comparative Examples 1 to 6 are mounted on a process cartridge as shown in FIG. 7, mounted in a tandem type full color image forming apparatus as shown in FIG. An exposure assessment was performed. A 655 nm semiconductor laser (image writing by a polygon mirror) was used as an image exposure light source, a roller charger as a charging member, a transfer belt as a transfer member, and a 655 nm LED as a charge removal light source. The process conditions before the test were set as follows.
<Process conditions before testing>
Photoconductor charging potential (unexposed portion potential): -700 V
Development bias: -500V

The evaluation was performed by measuring the unexposed portion potential of the photoreceptor and the exposed portion potential. As a measuring method, a surface potential meter is mounted at the position of the developing portion shown in FIG. 8, the photosensitive member is fixed to an applied bias charged to −700 V in the initial state, and the surface potential of the unexposed portion at the developing portion position and the exposure are fixed. The surface potential was measured.
Further, the image composed of the character part and the halftone part shown in FIG. 9 was output so that one of the character parts was at the head, and the degree of afterimage of the character part formed in the halftone part was visually evaluated.
As evaluation criteria, a very good one was represented by A, a next best one was B, a next best one was C, an inferior one was D, and a very bad one was represented by a five-step evaluation. These evaluations were performed before and after exposure to NOx gas. The NOx gas exposure conditions are as shown below. The above results are shown in Table 16 below.
<NOx gas exposure conditions>
Equipment: NOEX exposure test equipment manufactured by Directec Nitric oxide concentration: 50 ppm
Nitrogen dioxide concentration: 50ppm
Temperature: 35 ° C
Relative humidity: 55%
Exposure period: 10 days

As is apparent from Table 16, in the electrophotographic photoreceptors of the present invention produced in the examples, the degree of afterimage is good even after exposure to gas, and the decrease in the unexposed portion potential is small.
That is, all of Examples 1 to 6 are good results, and in Examples 1, 2, and 3 containing a charge transporting compound having a triarylamine structure in the step of contacting a supercritical fluid and / or a subcritical fluid. The exposed portion potential is low and excellent.
In addition, the types of antioxidants added in the steps of contacting the supercritical fluid and / or subcritical fluid in Examples 1 to 14 include phenolic antioxidants and phosphorus antioxidants after exposure to NOx gas. It can be seen that the afterimage is very good.
In Examples 15 and 16, methanol and ethanol are mixed as the supercritical fluid and / or subcritical fluid in the step of contacting the supercritical fluid and / or subcritical fluid. The afterimage after gas exposure is good.
In Examples 8, 17, 18, and 19, the afterimage after exposure to NOx gas is better as the amount of antioxidant added in the step of contacting the supercritical fluid and / or subcritical fluid is increased.
Further, in Examples 20, 21, 22, and 23 in which the temperature (90 ° C.) maintained in the step of contacting the supercritical fluid and / or subcritical fluid in Example 8 was changed, the higher the temperature, the more the NOx gas was exposed. The afterimage is good.
Examples 24 to 29 include a polymerizable compound having a charge transporting structure in the crosslinked surface layer coating solution. The exposed portion potential is slightly higher than that of Example 9, but good characteristics. I know that there is.
Further, in Examples 24 to 26 including the charge transporting compound in the step of bringing the supercritical fluid and / or subcritical fluid into contact with each other, the exposed portion potential is lower than those in Examples 27 to 29. Further, in Example 30 to which thermal energy was applied as polymerization energy instead of light energy, the afterimage characteristics and the electrical characteristics were good.
On the other hand, in Comparative Example 1 in which the crosslinked surface protective layer is not provided, the degree of afterimage after exposure to NOx gas is poor. In Comparative Example 2 except for the step of bringing the supercritical fluid and / or subcritical fluid into contact, since the charge transporting compound was not present in the crosslinked surface layer, the potential of the exposed area was large from the beginning, and the evaluation was stopped. Further, in Comparative Examples 3 and 4 that do not contain an antioxidant in the step of contacting the supercritical fluid and / or subcritical fluid, the afterimage after exposure to NOx gas is very bad and the potential of the exposed area is greatly reduced. .
In Comparative Example 5 prepared according to Japanese Patent Application Laid-Open No. 2006-99028 and Comparative Example 6 prepared according to Japanese Patent Application Laid-Open No. 2006-11014, an afterimage having a poor level is generated after exposure to NOx gas. The body surface potential is also greatly reduced. All of these contain an antioxidant in the cross-linked surface layer coating solution, and when the cross-linked surface layer is photocured, excessive energy is irradiated, which causes deterioration of the charge transporting compound and the antioxidant. It cannot be avoided, and it does not have sufficiently satisfactory characteristics under the severe exposure conditions of oxidizing gas.

<Real machine accelerated fatigue evaluation>
Next, the electrophotographic photosensitive member produced in Examples 1 to 30 and Comparative Examples 1, 5, and 6 is mounted on a process cartridge as shown in FIG. 7 and mounted on a tandem type full-color image forming apparatus as shown in FIG. The actual machine accelerated fatigue was evaluated. A 655 nm semiconductor laser (image writing by a polygon mirror) was used as an image exposure light source, a roller charger as a charging member, a transfer belt as a transfer member, and a 655 nm LED as a charge removal light source.
The process conditions before the test were set as follows.
<Process conditions before testing>
Photoconductor charging potential (unexposed portion potential): -700 V
Development bias: -500V
<Passing conditions>
As a sheet passing condition, a chart with a writing rate of 6% (characters equivalent to 6% as an image area are written on the entire A4 surface) is used. The contact pressure of the cleaning blade and the electrophotographic photosensitive member The applied bias to the charging member and the amount of light of the semiconductor laser were set so that the passing charge amount was twice that of the pre-test process conditions, and 100,000 sheets were continuously printed.

The evaluation was performed by measuring the unexposed portion potential and the exposed portion potential before and after 100,000 images were printed. As a measuring method, a surface potential meter is mounted at the developing portion position shown in FIG. 8, and the photosensitive member is fixed to an applied bias charged to −700 V in the initial state, and the surface potential of the unexposed portion and the exposed portion at the developing portion position are fixed. The potential was measured. Further, the difference in film thickness (amount of wear) before and after all tests was evaluated. The film thickness was measured at intervals of 1 cm, excluding 5 cm at both ends in the longitudinal direction of the electrophotographic photosensitive member, and the average value was taken as the film thickness. Furthermore, after printing 50,000 sheets, an all-white image was output, and the stain on the background portion was evaluated.
The image evaluation of the background portion was carried out in 4 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 ×.
Further, after printing 100,000 sheets, an ISO / JIS-SCID image N1 (portrait) was output to evaluate the color color reproducibility. The color reproducibility evaluation was carried out in four stages. Very good ones were indicated by ◎, good ones were indicated by ○, slightly inferior ones by Δ, and very bad ones by x. The above results are shown in Table 17 below.

As is clear from Table 17, all of the electrophotographic photoreceptors of the present invention produced in the examples showed extremely stable electrical characteristics even after passing 100,000 sheets, and images such as background stains and color balance were observed. The characteristics are also good, and the wear amount of the crosslinked surface layer is small.
In particular, in Examples 8, 9, 12, and 15 to 29 in which the charge blocking layer is provided in the intermediate layer, it is found that the background stain is very good.
In Examples 1 to 9, it can be seen that the greater the functional group of the polymerizable compound contained in the crosslinked surface layer coating solution, the smaller the wear amount.
Also, in Examples 24 to 29 containing a polymerizable compound having a charge transporting structure in the crosslinked surface layer coating solution, the amount of wear was slightly increased as compared with Example 9, and the crosslinked surface Since the polymerizable compound having a charge transporting structure added at the time of photocuring of the layer absorbs UV light, the polymerization efficiency is lost, and the crosslinking density is slightly reduced accordingly. Can be estimated. In Example 30 using thermal energy instead of light energy as polymerization energy, both electrical characteristics and mechanical durability are realized.
On the other hand, Comparative Example 1 having no cross-linked surface protective layer has a large amount of wear and a large decrease in film thickness. Comparative Example 5 and Comparative Example 6 have a large degree of increase in the exposed area potential, lack electrical stability compared to the Examples, have a slightly inferior color balance compared to the Examples, and have a large amount of wear. The UV light was absorbed by the charge transporting compound and the antioxidant contained therein, and the polymerization efficiency was lowered. Therefore, it was estimated that the crosslinking density was lowered as compared with the Examples.

From the above results, good results were obtained in all of the examples of the present invention, electrical characteristics were extremely stable, mechanical durability was high, abnormal images such as afterimages were not generated, and high reliability was achieved. An electrophotographic photosensitive member is realized. That is, an electrophotographic photosensitive member that has achieved high wear resistance and good electrical characteristics over a long period of time has been realized. On the other hand, Comparative Examples 1 to 6 have insufficient opportunity durability, and image characteristics such as afterimages and color balance after exposure to NOx gas have deteriorated, and the electrophotographic photosensitive member has high reliability over a long period of time. Has not been realized.
Therefore, in the method for producing an electrophotographic photosensitive member in which at least a photosensitive layer and a surface protective layer are sequentially formed on a conductive support, the surface protective layer is formed by previously polymerizing a polymerizable compound and a cured resin layer. After that, by performing contact with a supercritical fluid and / or subcritical fluid containing at least one antioxidant in the cured resin layer, maintaining high durability and having extremely stable electrical characteristics, It has been clarified that an electrophotographic photosensitive member having extremely high reliability is realized, and an electrophotographic photosensitive member capable of realizing high-quality image output over a long period of time can be provided. Also, a method for producing an electrophotographic photosensitive member of the present invention, an electrophotographic photosensitive member using the same, an image forming apparatus using the same, a process cartridge for an image forming apparatus using the same, and an image using the same It was revealed that the forming method has high performance and high reliability.

FIG. 2 is a cross-sectional view showing a configuration example of an electrophotographic photosensitive member in the present invention, in which a photosensitive layer 33 and a surface protective layer 39 are provided on a conductive support 31. FIG. 5 is a cross-sectional view showing another configuration example of the electrophotographic photosensitive member in the present invention, in which a charge generation layer 35, a charge transport layer 37, and a surface protective layer 39 are provided on a conductive support 31. FIG. 6 is a cross-sectional view showing still another configuration in the present invention, in which an intermediate layer 41, a charge generation layer 35, a charge transport layer 37 and a surface protective layer 39 are provided on a conductive support 31. 1 is a schematic diagram illustrating an example of an image forming apparatus configuration and an image forming process in the present invention. FIG. 3 is a schematic diagram illustrating an example of a proximity charging mechanism (a gap forming member is disposed on the charging member side) in the image forming apparatus of the present invention. It is the schematic which shows another example of the image formation apparatus structure in this invention, and an image formation process. FIG. 2 is a schematic diagram illustrating a configuration example of a process cartridge for an image forming apparatus according to the present invention. FIG. 6 is a schematic diagram for explaining another example (tandem type full-color electrophotographic apparatus) of the image forming apparatus according to the present invention. It is the output image used for the afterimage evaluation in the Example of this invention.

Explanation of symbols

1 to 3
31 Conductive Support 33 Photosensitive Layer 35 Charge Generation Layer 37 Charge Transport Layer 39 Surface Protective Layer 41 Intermediate Layer FIG.
DESCRIPTION OF SYMBOLS 1 Photoconductor 2 Separation claw 3 Charging roller 5 Image exposure part 6 Development unit 7 Charger before transfer 8 Registration roller 9 Transfer paper 10 Transfer charger 11 Separation charger 12 Separation claw 13 Charger before cleaning 14 Fur brush 15 Blade FIG.
DESCRIPTION OF SYMBOLS 1 Photoconductor 3 Charging roller 21 Gap formation member 22 Metal shaft 23 Image formation area 24 Non-image formation area FIG.
21 Photoconductors 22a and 22b Drive roller 23 Charger charger 24 Image exposure source 25 Transfer charger 26 Pre-cleaning exposure light source 27 Cleaning brush 28 Static elimination light source FIG.
DESCRIPTION OF SYMBOLS 1 Photoconductor 3 Charging roller 5 Image exposure part 15 Cleaning brush 16 Developing roller 17 Transfer roller FIG.
1C, 1M, 1Y, 1K Photoconductor 2C, 2M, 2Y, 2K Charging member 3C, 3M, 3Y, 3K Laser light 4C, 4M, 4Y, 4K Developing member 5C, 5M, 5Y, 5K Cleaning member 6C, 6M, 6Y , 6K image forming element 7 transfer paper 8 paper feeding roller 9 registration roller 10 transfer conveying belt 11C, 11M, 11Y, 11K transfer brush 12 fixing device

Claims (20)

In the method for producing an electrophotographic photosensitive member formed by sequentially forming at least a photosensitive layer and a surface protective layer on a conductive support,
The surface protective layer is formed by polymerizing a polymerizable compound in advance to obtain a cured resin layer, and then contacting the cured resin layer with a supercritical fluid and / or a subcritical fluid containing at least one antioxidant. A method for producing an electrophotographic photosensitive member.   The method for producing an electrophotographic photosensitive member according to claim 1, wherein the cured resin layer is formed by photopolymerization of a radical polymerizable compound.   The method for producing an electrophotographic photosensitive member according to claim 1, wherein the supercritical fluid and / or the subcritical fluid is carbon dioxide.   The method for producing an electrophotographic photosensitive member according to claim 1, wherein the supercritical fluid and / or subcritical fluid is a mixture containing at least carbon dioxide.   The method for producing an electrophotographic photosensitive member according to claim 4, wherein the carbon dioxide-containing mixture is at least one selected from methanol and ethanol.   The electron according to any one of claims 1 to 5, wherein the content of at least one or more antioxidants contained in the supercritical fluid and / or subcritical fluid is 0.5 g / L or more. A method for producing a photographic photoreceptor.   The method for producing an electrophotographic photosensitive member according to any one of claims 1 to 6, wherein the temperature of the supercritical fluid and / or subcritical fluid is 30 to 140 ° C.   The method for producing an electrophotographic photosensitive member according to claim 1, wherein at least one of the antioxidants is a phenolic antioxidant.   The method for producing an electrophotographic photosensitive member according to claim 1, wherein at least one of the antioxidants is a phosphorus-based antioxidant.   8. The electrophotographic photosensitive member according to claim 1, wherein the at least one or more antioxidants are selected from one or more phenol-based antioxidants and one or more phosphorus-based antioxidants. Production method.   11. The method for producing an electrophotographic photosensitive member according to claim 1, wherein a charge transporting compound is contained in the supercritical fluid and / or the subcritical fluid.   The method for producing an electrophotographic photosensitive member according to claim 11, wherein the charge transporting compound does not have a polymerizable functional group.   The electrophotographic photosensitive member according to claim 11 or 12, wherein the charge transporting compound is selected from the group consisting of compounds having a triarylamine structure, a hydrazone structure, a pyrazoline structure, and a carbazole structure. Manufacturing method.   The method for producing an electrophotographic photosensitive member according to claim 11, wherein the charge transporting compound is a compound having a triarylamine structure.   The method for producing an electrophotographic photosensitive member according to claim 1, wherein the polymerizable compound is a compound having no charge transporting structure.   The method for producing an electrophotographic photosensitive member according to claim 1, wherein the polymerizable compound has three or more polymerizable functional groups.   An electrophotographic photoreceptor produced by the production method according to claim 1.   An electrophotographic photosensitive member according to claim 17, a charging means for charging at least the electrophotographic photosensitive member, a latent image forming means for forming an electrostatic latent image on the surface of the electrophotographic photosensitive member charged by the charging means, Developing means for attaching toner to the electrostatic latent image formed by the latent image forming means, transfer means for transferring the toner image formed by the developing means to the transfer target, and remaining on the surface of the electrophotographic photosensitive member after transfer An image forming apparatus comprising: a cleaning unit that removes toner from the surface of the electrophotographic photosensitive member.   An electrophotographic photosensitive member according to claim 17, a charging means for charging at least the electrophotographic photosensitive member, a latent image forming means for forming an electrostatic latent image on the surface of the electrophotographic photosensitive member charged by the charging means, Developing means for attaching toner to the electrostatic latent image formed by the latent image forming means, transfer means for transferring the toner image formed by the developing means to the transfer target, and remaining on the surface of the electrophotographic photosensitive member after transfer A process cartridge for an image forming apparatus having one means selected from the group consisting of cleaning means for removing toner from the surface of an electrophotographic photosensitive member, wherein the process cartridge is detachable from an image forming apparatus main body.   At least the electrophotographic photosensitive member according to claim 17 is charged by a charging unit, an electrostatic latent image is formed by a latent image forming unit on the surface of the electrophotographic photosensitive member charged by the charging unit, and the latent image forming unit forms the electrostatic latent image. The toner is attached to the electrostatic latent image by the developing means, the toner image formed by the developing means is transferred to the transfer target by the transferring means, and the toner remaining on the surface of the electrophotographic photosensitive member after the transfer is electrophotographic photosensitive by the cleaning means. An image forming method comprising forming an image by removing from a body surface.