JP4771920B2 - Electrophotographic photosensitive member reproduction methods, and electrophotographic photosensitive members and image forming apparatuses obtained by these methods. - Google Patents

Description

  The present invention relates to a method for reproducing an electrophotographic photosensitive member, an electrophotographic photosensitive member, an image forming apparatus, and a process cartridge.

  In recent years, full-color, high-speed, and miniaturization of image forming apparatuses are rapidly progressing. In particular, the demand for color printing is increasing, and tandem-type image forming apparatuses capable of increasing the speed of full-color image output are becoming mainstream. Since the tandem image forming apparatus includes four photosensitive members corresponding to at least four color developing units, it is unavoidable to increase the size of the apparatus, and a reduction in the diameter of the photosensitive member is required. Therefore, full color, high speed and downsizing of the image forming apparatus are problems that must be considered simultaneously, and in order to realize them, it is essential to improve the durability of the photoconductor included.

  Inorganic photoreceptors are advantageous in terms of abrasion resistance compared to organic photoreceptors, but are inferior in productivity, cost, pollution-free property, etc., and organic photoreceptors are now widely used. Further, the wear resistance has been remarkably improved due to the improvement of the protective layer technology of the organic photoreceptor, and the development for improving the durability of the organic photoreceptor has been actively conducted. However, even if the wear resistance is improved, the durability is not sufficiently satisfied because the influence of the deterioration of electrostatic characteristics such as a decrease in sensitivity and an increase in residual potential is large. One of the factors is that the organic material constituting the organic photoreceptor has many factors that trap electric charges. In particular, a charge generating substance, a charge transporting substance, or a binder resin needs to maintain high purity.

  In order to increase the purity of those photosensitive materials and binder resins used for the photoreceptor, it is necessary to carry out a purification process carefully. However, in the conventional method for purifying the photosensitive material and the binder resin, it is necessary to carry out the purification process many times in order to increase the purity, and the purification process includes steps such as washing, filtration, and drying. A lot of time and various facilities are required. Furthermore, it was necessary to select an organic solvent suitable for the material to be purified, and the efficiency of the purification process was very low. For this reason, a large amount of organic solvent is required over a long period of time to purify the material, and the amount of waste liquid is increased.

  These impurities that affect sensitivity reduction and residual potential increase, etc., are generated from chargers over the course of use, in addition to raw materials, intermediates, and external contaminants remaining in the manufacturing process of photosensitive materials and binder resins. This includes the effects of decomposition and alteration of the photosensitive material due to exposure to ozone and NOx gas. As described above, the photosensitive material is easily deteriorated with time, and has a great influence on the deterioration of electrophotographic characteristics because it plays the role of charge generation and charge transport.

  Furthermore, the adhesion of foreign matter due to the developer component on the surface of the photoconductor or paper dust caused by repeated use of the photoconductor greatly reduces the durability of the photoconductor. If the photoconductor wear resistance is low, it will be removed immediately even if foreign matter adheres to the surface of the photoconductor. However, if the photoconductor wear resistance is improved for high durability, Removal becomes difficult, and abnormal images are generated. Therefore, even if the wear resistance is sufficient, the actual condition is that the photosensitive member reaches the end of its life due to the occurrence of an abnormal image due to adhesion of foreign matter and the like, and the high durability of the photosensitive member is not sufficiently satisfied. From the above, the organic photoreceptor is forced to be replaced in a relatively short cycle even though the wear resistance is improved by the improvement of the protective layer technology.

  The amount of organic solvent used and discharged in the process of manufacturing a photoconductor by synthesis and purification of photosensitive materials, preparation of coating solutions, photoconductor coating, etc. is very large. There is a need to reduce the amount of In addition, the influence of the organic photoreceptor is larger than that of the inorganic photoreceptor, and the life of the photoreceptor is short. For this reason, apart from the high durability technology of the photoconductor, many technologies for regenerating the photoconductor that has reached the end of its life have been disclosed.

  As an example of a method for regenerating the photoreceptor, a method of heating after the glass transition point of the charge transporting layer is cooled and then cooling, and the protective layer is peeled off and reapplied (Patent Document 1: Japanese Patent Laid-Open No. 2003-086993) has deteriorated. A method of recoating the photosensitive layer on the photoreceptor (Patent Document 2: Japanese Patent Laid-Open No. 2001-235878), and a method of directly forming a reproduction layer on the remaining layer of the used photoconductor (Patent Document 3: Japanese Patent Laid-Open No. 2001-2001). 117243), a method of forming a three-dimensional crosslinked film directly under the charge transport layer, peeling and recoating the charge transport layer (Patent Document 4: Japanese Patent Laid-Open No. 2001-201883), and a constant film thickness by precision polishing. A method of removing the photosensitive layer while leaving a film and forming a new surface layer (Patent Document 5: Japanese Patent Application Laid-Open No. 2001-075295), and repairing a photosensitive member whose surface is damaged by exposure to a vapor of a solvent to be dissolved. Direction (Patent Document 6: Japanese Patent Laid-Open No. 2000-147796), a method of dissolving, cutting or peeling only the photosensitive layer of the photoconductor to form a photosensitive layer again (Patent Document 7: Japanese Patent Laid-Open No. 11-341537), phenylene A method of heat-treating at a temperature higher than the glass transition temperature of a photosensitive layer containing a diamine-based charge transport material (Patent Document 8: JP-A-3-161757) is disclosed.

  If the photoconductor can be regenerated, the image quality can be maintained by replacing it with the regenerated photoconductor, and the amount of organic solvent used and waste can be greatly reduced. This is a very effective method. However, most of the above-mentioned photoreceptor regeneration techniques are those in which the photosensitive layer is peeled off and re-applied, and peeling and re-applying the photosensitive layer requires a lot of labor and cost, is inefficient, and is practical. It was very scarce. Further, when peeled off, foreign matter may remain, and it is not sufficient for removing decomposition products and the like inside the photosensitive layer, and the effect of the regeneration processing is also poor. Therefore, the conventional reproduction method is costly and ineffective, and is far from practical use. From the viewpoint of environmental protection, there has been a strong demand for early realization of the reproduction method of the photoreceptor.

  On the other hand, a method using a supercritical fluid is disclosed as a method for cleaning and purifying materials. Supercritical fluid is a high-density liquid phase obtained when the temperature and pressure are higher than the critical point, and since it has both high liquid dissolving power and high gas diffusivity, it has begun to be applied in various fields. . The following technologies are also disclosed in the field of electrophotographic photoreceptors. For example, methods for cleaning, purifying, extracting, and crystallizing charge generating materials are disclosed (see Patent Documents 9 to 12). It is also disclosed as a method for cleaning a conductive support (Patent Document 13: Japanese Patent Laid-Open No. 2001-121094). It is also disclosed as a method for purifying resin fine particles contained in the surface layer (Patent Document 14: JP-A-7-134435, Patent Document 15: Patent 3186010).

  In this way, by processing these photosensitive materials contained in the photoreceptor with a supercritical fluid, the electrophotographic characteristics are improved and the material can be purified more efficiently. A material purification method using the supercritical fluid Can be said to be a very effective method in the field of photoreceptors. However, these methods are merely for cleaning and refining the photosensitive material, and have no effect of reducing a large amount of organic solvent used by preparing and coating the coating solution. In addition, the problem with the processing of a photoconductor that has reached the end of its life due to the occurrence of an abnormal image cannot be solved. In order to reduce environmental impact caused by the large amount of organic solvent generated in the photoconductor manufacturing process, and to reduce the amount and cost of used photoconductors to be discarded and processed, the photoconductors have dramatically improved durability. However, there is a lack of feasibility in the conventionally known methods, and there has been a strong demand for solving the problems.

JP 2003-086993 A JP 2001-235878 A JP 2001-117243 A JP 2001-201883 A JP 2001-075295 A JP 2000-147796 A Japanese Patent Laid-Open No. 11-341537 JP-A-3-161757 JP-A-7-134435 JP 2001-092165 A JP 2002-138216 A JP 2002-356627 A JP 2001-121094 A JP-A-7-134435 Japanese Patent No. 3186010

  The present invention provides an efficient and effective new method for regenerating a photoconductor that could not be realized by the conventional method in view of the problems of the above-described conventional techniques, and thereby enables a significant reduction in the amount of organic solvent used. Another object of the present invention is to provide an electrophotographic photosensitive member that has been reproduced so that a high-quality image can be stably output with respect to a photosensitive member that has reached the end of its life, and an image forming apparatus and a process cartridge using the same.

  As a result of intensive studies on a method for reproducing an electrophotographic photosensitive member, the present invention provides a very easy and efficient method for bringing a repeatedly used electrophotographic photosensitive member itself into contact with a supercritical fluid and / or a subcritical fluid. I came to find it. Since this method has a high cleaning effect, not only impurities contained from the time of photoconductor preparation, but also decomposition products or reaction products generated on the surface or inside of the photosensitive layer by repeated use in the image forming apparatus. Can also be removed. In addition, it is possible to easily remove foreign substances such as developer components and paper dust that have adhered to the surface of the photoconductor that cause abnormal images. The very excellent point of the reproducing method of the present invention is that the supercritical fluid and / or subcritical fluid penetrates not only to the surface of the photoreceptor but also to the inside of the layer, thereby removing impurities and foreign matters inside the layer. This is possible. In addition, since the supercritical fluid and / or subcritical fluid is a gas at normal temperature and normal pressure, it has excellent drying properties, and the supercritical fluid and / or subcritical fluid remains inside the layer only by returning to normal temperature and normal pressure. In addition, no drying process or post-treatment is required, which is another reason why the regeneration efficiency is very high.

That is, the said subject is solved by the following this invention.
(1) “Charging step for charging at least the surface of the electrophotographic photosensitive member, electrostatic latent image forming step for forming an electrostatic latent image on the electrophotographic photosensitive member, and adhesion of toner to the electrostatic latent image. A supercritical fluid and / or a subcritical fluid is brought into contact with the surface of an electrophotographic photoreceptor repeatedly used in an image forming process including a developing process for forming a visual image and a transfer process for transferring the visible image to a recording medium. A method for reproducing an electrophotographic photosensitive member,
(2) “The method for regenerating an electrophotographic photosensitive member according to item (1), wherein a protective layer is formed on a surface of the electrophotographic photosensitive member”,
(3) "The method for regenerating an electrophotographic photosensitive member according to (2) above, wherein the protective layer contains a binder resin obtained by crosslinking treatment",
(4) The method for regenerating an electrophotographic photosensitive member according to any one of (1) to (3) above, wherein the supercritical fluid and / or subcritical fluid is carbon dioxide. "
(5) "The method for regenerating an electrophotographic photosensitive member according to (4) above, wherein the supercritical fluid and / or subcritical fluid is a mixture with carbon dioxide",
(6) The above (5), wherein the mixture is a mixture of carbon dioxide and at least one selected from carbon monoxide, nitrogen, water, ammonia, methanol, ethanol, ethane, and propane. Reproducing method of electrophotographic photosensitive member according to item ",
(7) “Reproduction of electrophotographic photosensitive member according to any one of (1) to (6) above, wherein the supercritical fluid and / or subcritical fluid is circulated in the contacting step. Method",
(8) The items (1) to (1), wherein a substance other than the binder resin contained in the outermost surface layer of the electrophotographic photosensitive member is previously contained in a supercritical fluid and / or a subcritical fluid. The method for regenerating an electrophotographic photosensitive member according to any one of items (7) ",
(9) “Electrophotographic photosensitive member characterized by being reproduced by the reproducing method according to any one of (1) to (8)”,
(10) “Charging step for charging at least the surface of the electrophotographic photosensitive member, an electrostatic latent image forming step for forming an electrostatic latent image on the electrophotographic photosensitive member, and allowing toner to adhere to the electrostatic latent image. An image forming method comprising a developing step for forming a visual image and a transfer step for transferring the visible image to a recording medium, wherein the electrophotographic photosensitive member is the electrophotographic photosensitive member according to (9). An image forming method characterized in that "
(11) “Charging means for charging at least the surface of the electrophotographic photosensitive member, electrostatic latent image forming means for forming an electrostatic latent image on the electrophotographic photosensitive member, and toner can be attached to the electrostatic latent image. An image forming apparatus including a developing unit for forming a visual image and a transfer unit for transferring the visible image to a recording medium, wherein the electrophotographic photosensitive member is the electrophotographic photosensitive member according to (9). An image forming apparatus characterized by being ",
(12) “Charging means for charging the surface of the electrophotographic photosensitive member, electrostatic latent image forming means for forming an electrostatic latent image on the electrophotographic photosensitive member, and visible toner by attaching toner to the electrostatic latent image At least one means selected from a developing means for forming an image, a transfer means for transferring the visible image to a recording medium, and a cleaning means for removing toner remaining on the surface of the electrophotographic photosensitive member after the transfer; A process cartridge for an image forming apparatus, which is integrated with the electrophotographic photosensitive member according to item (9) and is detachable from the main body of the image forming apparatus.

  Unlike the conventional regeneration method, the regeneration method of the present invention does not require film peeling, recoating, or drying, and impurities and foreign matters that adversely affect the photoreceptor due to repeated use of the photoreceptor, such as repeated use. It is possible to clean not only the surface of the photosensitive layer but also the inside of the layer by removing foreign substances such as decomposition products and oxides generated by the above, or developer components adhering to the surface of the photoreceptor, paper dust, and discharge products. Provided is a method for reproducing a photoreceptor that is excellent in efficiency, simple, low cost, and extremely effective. In particular, supercritical fluids or subcritical fluids that are gases under normal temperature and normal pressure, such as carbon dioxide, have both high solubility and permeability, so they have a high cleaning effect, and only on the surface of the photosensitive layer. As a method of regenerating the photoconductor, it can be cleaned up to the inside and is excellent in drying without supercritical fluid or subcritical fluid remaining inside because it is a gas at normal temperature and pressure. Is very suitable and is an epoch-making playback method that has never existed before.

Further, the advantage of the reproducing method of the present invention is that a new material can be injected into the layer of the photoreceptor as required. Decomposition and alteration of photosensitive materials occur due to repeated use of the photoreceptor, and cleaning and removing them is effective for improving the image quality, but the amount of photosensitive material required in the layer by removing them is effective. It will be reduced. When the reproduction process is repeated many times, the influence cannot be ignored, and the reproduction effect is reduced by the decrease in the photosensitive material that exhibits the function of the photoreceptor. However, the regenerating method of the present invention extracts and removes only a decomposed / denatured photosensitive material by preliminarily containing a new photosensitive material in a supercritical fluid and / or a subcritical fluid, and decomposes / degrades it. It is possible to control so that no normal photosensitive material is detached from the layer. Further, by increasing the amount of the new photosensitive material previously contained in the supercritical fluid and / or the subcritical fluid, it is possible to inject the new photosensitive material into the layer of the photosensitive member. In addition to extracting / removing the decomposed and altered photosensitive material, it is possible to simultaneously inject and supplement the insufficient photosensitive material. Thereby, it is possible to realize reproduction to a level comparable to that of a photoconductor just manufactured.
As a result, it was possible to remove impurities inside the photoconductor, which was one of the causes of sensitivity deterioration and residual potential rise, and foreign matter on the surface of the photoconductor that was the cause of abnormal image generation. Stabilization is realized again, and a photoconductor that has reached the end of its life can be reused, and a regenerated photoconductor is provided. In addition, an image forming apparatus and a process cartridge that can output a high-quality image again using the reproduced photoreceptor are provided. As a result, a large reduction in the amount of organic solvent used in the process of producing the photoconductor can be realized, the energy required for processing the used photoconductor can be greatly reduced, and the use of the regenerated photoconductor The image forming apparatus and the process cartridge can be reused, which is a very effective method for environmental protection.

Next, the best mode for carrying out the present invention will be described.
First, the supercritical fluid or subcritical fluid will be described.
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 is no restriction | limiting in particular, Although it can select suitably according to the objective, A thing with a lower critical temperature is preferable. In addition, the subcritical fluid in the present invention means a state where one of temperature and pressure exceeds a critical point. In the present invention, it is needless to say that the effect can be obtained even if it is not necessarily in the supercritical state. Supercritical fluid has both characteristics of gas and liquid, and it is considered that it is effective that it is in a state close to a high-density liquid particularly during processing. When carbon dioxide is used, it is a gas at room temperature and normal pressure, but it can be said that it is effective even if it is not in a supercritical state when it becomes a liquid state. For example, the critical pressure of carbon dioxide is 7.53 MPa. It has been confirmed by experiments that if the pressure is higher than that, the density rapidly increases even if the critical temperature is not below 31 ° C. From this result, if the pressure is 7.53 MPa or more and the density is at least 0.7 (g / cm ³ ) or more, it can be determined that the subcritical state is reached even if the critical temperature is not reached. However, this is a case of carbon dioxide, and cannot be applied to a fluid that is liquid at normal temperature and pressure.
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. Preferred examples of these fluids include carbon monoxide, carbon dioxide, ammonia, nitrogen, water, methanol, ethanol, ethane, propane, 2,3-dimethylbutane, benzene, chlorotrifluoromethane, and dimethyl ether. . Among these, carbon dioxide is particularly preferable in that the critical temperature is close to room temperature and the handleability is excellent.

  A supercritical fluid having a critical temperature of 30 to 40 ° C. and close to normal temperature, for example, supercritical carbon dioxide and supercritical carbon monoxide, is desirably used at a temperature of 20 to 150 ° C. and a pressure of 5 to 70 MPa. 100 degreeC and 7-50 Mpa are more preferable. If the temperature is less than 20 ° C. or the pressure is less than 5 MPa, carbon dioxide and carbon monoxide are not preferable because they are unlikely to be in a supercritical state. On the other hand, when the temperature exceeds 150 ° C., the constituent material of the photoconductor may be dissolved or decomposed in some cases, and when the pressure exceeds 70 MPa, in addition to the above reason, the apparatus including the fluid pump or the like may be used. This is not preferable because it may hinder driving. Incidentally, the critical temperature of carbon dioxide is 31 ° C., the critical pressure is 7.53 MPa, the critical temperature of carbon monoxide is 37 ° C., and the critical pressure is 7.26 MPa.

  Since the use of the supercritical fluid or subcritical fluid in the present invention is intended to regenerate the used photoreceptor, the temperature at which the binder resin contained in the layer in contact with the supercritical fluid or subcritical fluid is not completely dissolved. It is preferable to maintain the pressure. If the amount of the binder resin dissolved becomes large, it may not be maintained as a film. However, since the binder resin is dissolved selectively from those having a lower molecular weight in the molecular weight distribution of the binder resin, there is no problem if the amount is small, and the molecular weight distribution becomes sharper. Can also be expected.

  On the other hand, in the present invention, it is more preferable that the binder resin is swollen to some extent even if the binder resin does not dissolve at all. In order to remove impurities and the like contained in the layer out of the system, it is necessary to swell the resin so that the substance easily moves between the resin molecular chains. In order to swell the binder resin, it is possible to set it to a temperature equal to or higher than the glass transition temperature of the binder resin, but it is sufficient to set the temperature and pressure conditions while confirming the physical properties and effects of the resin used, and the desired cleaning. The fact that the conditions can be arbitrarily set in order to obtain an effect is very excellent in practicality of the present invention.

  The various materials mentioned as the supercritical fluid can also be suitably used as a subcritical fluid having a temperature slightly lower than the temperature in the supercritical state or a pressure slightly lower than the pressure in the supercritical state. In other words, the effect can be obtained even when a subcritical fluid such as subcritical carbon dioxide is brought into contact with the photoreceptor. In the case of a supercritical fluid, the solubility may be too high. When used as a regeneration method mainly for removing impurities and foreign matters of the present invention, it is preferable to use a subcritical fluid instead of the supercritical fluid. In some cases. Various materials mentioned as the supercritical fluid can be preferably used as the subcritical fluid.

  The supercritical fluid and the subcritical fluid may be used alone or as a mixture of two or more. When other fluids are used in addition to the supercritical fluid and the subcritical fluid, specifically, the above supercritical fluid or subcritical fluid such as carbon monoxide, nitrogen, ethane, propane, or ethylene is used in combination. can do. Moreover, an organic solvent can be mixed with the supercritical fluid and the subcritical fluid as an entrainer. There are no particular restrictions on the entrainer, such as alcohol solvents such as methanol and ethanol, hydrocarbon solvents such as hexane, cyclohexane and toluene, and ketone solvents such as acetone and methyl ethyl ketone, which are effective in enhancing the cleaning effect. . However, in the present invention, conditions for completely dissolving the binder resin as described above are not preferable. In the case of an inorganic photoconductor, a higher effect may be exhibited by using a supercritical fluid together or by mixing an entrainer. However, in the case of an organic photoconductor, there is no need to significantly increase the cleaning effect. As long as carbon dioxide alone is used, sufficient effects can be obtained.

  As the apparatus using the supercritical fluid or the subcritical fluid, any apparatus can be used as long as the photoconductor can be brought into contact with the supercritical fluid and / or the subcritical fluid. Also, a batch system that uses a supercritical fluid and / or subcritical fluid in a closed system, a distribution system that circulates and uses a supercritical fluid or a subcritical fluid, a combined system that combines a batch system and a distribution system, etc. Any of them can be used, but in order to remove impurities, a circulation method in which a supercritical fluid and / or a subcritical fluid is circulated is more preferable. Thereby, the extracted impurities can be taken out of the system.

  Also, when cleaning the photoreceptor using a supercritical fluid or subcritical fluid, depending on the temperature and pressure conditions, components other than the binder resin contained in the reclaimed layer may be extracted. There is. Although it is possible to adjust the temperature and pressure conditions so that they are not extracted, as another method, a component other than the binder resin of the layer to be regenerated into a supercritical fluid and / or a subcritical fluid is previously contained. Therefore, it is possible to keep those components in an equilibrium state in the photosensitive layer at the time of reproduction processing, and it is possible to remove only impurities and unnecessary materials, which is effective.

Hereinafter, the photoconductor including the manufacturing method will be described.
FIG. 1 shows a photosensitive member in which a photosensitive layer mainly composed of a charge generating substance, a charge transporting substance, and a binder resin is formed on a conductive support. As shown in FIG. 2, a protective layer can be formed on the outermost surface of the photoreceptor. These are photoreceptors that are repeatedly used in an image forming apparatus and then regenerated by contacting with a supercritical fluid and / or a subcritical fluid.
FIG. 3 shows a photoreceptor in which a charge generation layer mainly composed of a charge generation material and a binder resin, and a charge transport layer mainly composed of a charge transport material and a binder resin are sequentially laminated on a conductive support. As shown in FIG. 4, a protective layer can be formed on the outermost surface of the photoreceptor. These are photoreceptors that are repeatedly used in an image forming apparatus and then regenerated by contacting with a supercritical fluid and / or a subcritical fluid.
FIG. 5 shows a photoreceptor in which an undercoat layer, a charge generation material, a charge transport layer, and a photosensitive layer mainly composed of a binder resin are sequentially laminated on a conductive support. As shown in FIG. 6, it is possible to form a protective layer on the outermost surface of the photoreceptor. These are photoreceptors that are repeatedly used in an image forming apparatus and then regenerated by contacting with a supercritical fluid and / or a subcritical fluid. The undercoat layer may be a single layer or a plurality of layers.

<About conductive support>
Examples of the conductive support include those having a volume resistance of 10 ¹⁰ Ω · cm or less, such as aluminum, nickel, chromium, nichrome, copper, gold, silver, platinum and other metals, tin oxide, indium oxide, and the like. Metal oxide coated with film or cylindrical plastic or paper by vapor deposition or sputtering; aluminum, aluminum alloy, nickel, stainless steel, etc., and after they have been made into bare tubes by methods such as extrusion and drawing Pipes subjected to surface treatment such as cutting, super-finishing and polishing can be used. Endless nickel belts and endless stainless steel belts can also be used as the conductive support.

In addition to this, a conductive support prepared by dispersing conductive powder in a binder resin and coating a conductive layer on the conductive support can be used as the conductive support. Examples of the conductive powder include carbon black, acetylene black; metal powder such as aluminum, nickel, iron, nichrome, copper, zinc, silver, and metal oxide powder such as conductive tin oxide and ITO. 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, phenoxy resin, polycarbonate, cellulose acetate resin, ethyl cellulose resin, polyvinyl butyral, polyvinyl formal, polyvinyl toluene, poly (N-vinylcarbazole), acrylic resin, silicone resin, epoxy resin, melamine Examples thereof include thermoplastic resins such as resins, urethane resins, phenol resins, and alkyd resins, thermosetting resins, and photocurable resins. The conductive layer can be provided by dispersing conductive powder and a binder resin in a solvent such as tetrahydrofuran, dichloromethane, methyl ethyl ketone, or toluene and applying the conductive powder and the binder resin.
Furthermore, using a heat-shrinkable tube containing conductive powder in materials such as polyvinyl chloride, polypropylene, polyester, polystyrene, polyvinylidene chloride, polyethylene, chlorinated rubber, polytetrafluoroethylene fluororesin, etc. Those provided with a conductive layer can also be used as a conductive support.

<Regarding photosensitive layer having a laminated structure>
Next, the photosensitive layer will be described. Hereinafter, the laminated photosensitive layer will be described. The laminated photosensitive layer is roughly divided into a charge generation layer and a charge transport layer.
(About the charge generation layer)
The charge generation layer is a layer mainly composed of a charge generation material. For the charge generation layer, a known charge generation material can be used. For example, azo pigments such as monoazo pigments, disazo pigments, asymmetric disazo pigments, trisazo pigments; titanyl phthalocyanine, copper phthalocyanine, vanadyl phthalocyanine, hydroxygallium phthalocyanine Phthalocyanine pigments such as metal-free phthalocyanine; perylene pigments, perinone pigments, indigo pigments, pyrrolopyrrole pigments, anthraquinone pigments, quinacridone pigments, quinone condensed polycyclic compounds, squalium pigments, and the like. The charge generation materials may be used alone or in combination of two or more.

If necessary, the binder resin used in the charge generation layer may be polyamide, polyurethane, epoxy resin, polyketone, polycarbonate, silicone resin, acrylic resin, polyvinyl butyral, polyvinyl formal, polyvinyl ketone, polystyrene, polysulfone, poly (N- Vinyl carbazole), polyacrylamide, polyvinyl benzal, polyester, phenoxy resin, vinyl chloride-vinyl acetate copolymer, polyvinyl acetate, polyphenylene oxide, polyamide, polyvinyl pyridine, cellulose resin, casein, polyvinyl alcohol, polyvinyl pyrrolidone, etc. Can be mentioned.
The addition amount of the binder resin is usually 0 to 500 parts by weight, preferably 10 to 300 parts by weight with respect to 100 parts by weight of the charge generation material.

The charge generation layer is a conductive support that supports a coating solution in which a charge generation material is dispersed in a solvent using a known dispersion method such as ball mill, attritor, bead mill, sand mill, or ultrasonic wave together with a binder resin as necessary. It is formed by applying and drying on the body or undercoat layer. The binder resin may be added before or after the charge generating material is dispersed.
Solvents used here are generally used organic solvents such as isopropanol, acetone, methyl ethyl ketone, cyclohexanone, tetrahydrofuran, dioxane, ethyl cellosolve, ethyl acetate, methyl acetate, dichloromethane, dichloroethane, monochlorobenzene, cyclohexane, toluene, xylene, ligroin, etc. Among them, it is preferable to use a ketone solvent, an ester solvent, or an ether solvent. These may be used alone or in combination of two or more.
The coating solution for the charge generation layer is mainly composed of a charge generation material, a solvent, and a binder resin, and it contains additives such as a sensitizer, a dispersant, a surfactant, and silicone oil. May be.

  As a method for coating the charge generation layer using the coating solution, known methods such as dip coating, spray coating, beat coating, nozzle coating, spinner coating, ring coating, and the like can be used. The thickness of the charge generation layer is usually from 0.01 to 5 μm, preferably from 0.1 to 2 μm. After coating, it is heated and dried in an oven or the like. The drying temperature of the charge generation layer is preferably 50 to 160 ° C, more preferably 80 to 140 ° C.

(About charge transport layer)
The charge transport layer is formed by applying and drying a coating solution in which at least a charge transport material and a binder resin are dissolved or dispersed in a solvent.
Charge transport materials include hole transport materials and electron transport materials. 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.

  Examples of the hole transport material include poly (N-vinylcarbazole) and derivatives thereof, poly (γ-carbazolylethyl glutamate) and derivatives thereof, pyrene-formaldehyde condensates and derivatives thereof, polyvinylpyrene, polyvinylphenanthrene, polysilane, and oxazole. Derivatives, oxadiazole derivatives, imidazole derivatives, monoarylamine derivatives, diarylamine derivatives, triarylamine derivatives, stilbene derivatives, α-phenylstilbene derivatives, distyrylbenzene derivatives, aminobiphenyl derivatives, benzidine derivatives, diarylmethane derivatives, tria Lillemethane derivatives, 9-styrylanthracene derivatives, pyrazoline derivatives, divinylbenzene derivatives, hydrazone derivatives, indene derivatives, butadiene derivatives, pyrene derivatives Materials such as conductors, bisstilbene derivatives, enamine derivatives and the like can be mentioned. These charge transport materials may be used alone or in combination of two or more. The content of the charge transport material is usually 20 to 300 parts by weight and preferably 40 to 150 parts by weight with respect to 100 parts by weight of the binder resin.

  Binder resins include polystyrene, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer, polyester, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, polyvinyl acetate, poly Vinylidene chloride, polyarylate, phenoxy resin, polycarbonate, cellulose acetate resin, ethyl cellulose resin, polyvinyl butyral, polyvinyl formal, polyvinyl toluene, poly (N-vinylcarbazole), acrylic resin, silicone resin, epoxy resin, melamine resin, urethane resin, Thermoplastic or thermosetting resins such as phenol resin and alkyd resin can be mentioned, among which polycarbonate and polyarylate are preferable. Polycarbonate and polyarylate are not only highly transparent but also have little effect on residual potential increase and charge decrease, and are used effectively in the present invention.

  Further, as the binder resin, it is possible to use a polymer charge transport material having both the function of the binder resin and the function of the charge transport material, which may be effective in performing the regeneration treatment. As the polymer charge transporting material, known materials can be used, and in particular, the following polycarbonates having a triphenylamine structure are favorably used. An example of these polymer charge transport materials is shown.

式中、Ｒ_１、Ｒ_２、Ｒ_３はそれぞれ独立して置換もしくは無置換のアルキル基又はハロゲン原子、Ｒ_４は水素原子又は置換もしくは無置換のアルキル基、Ｒ_５、Ｒ_６は置換もしくは無置換のアリール基、ｏ、ｐ、ｑはそれぞれ独立して０〜４の整数、ｋ、ｊは組成を表わし、０．１≦ｋ≦１、０≦ｊ≦０．９、ｎは繰り返し単位数を表わし５〜５０００の整数である。Ｘは脂肪族の２価基、環状脂肪族の２価基、または下記一般式で表わされる２価基を表わす。なお、（Ｉ）式は２つの共重合種が交互共重合体の形で記載されているが、ランダム共重合体でも構わない。

In the formula, R ₁ , R ₂ and R ₃ are each independently a substituted or unsubstituted alkyl group or a halogen atom, R ₄ is a hydrogen atom or a substituted or unsubstituted alkyl group, and R ₅ and R ₆ are substituted or unsubstituted. Substituted 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 is the number of repeating units Represents an integer of 5 to 5000. X represents an aliphatic divalent group, a cycloaliphatic divalent group, or a divalent group represented by the following general formula. In the formula (I), two copolymer species are described in the form of an alternating copolymer, but a random copolymer may be used.

Ｒ_１０１、Ｒ_１０２は各々独立して置換もしくは無置換のアルキル基、アリール基またはハロゲン原子を表わす。ｌ、ｍは０〜４の整数、Ｙは単結合、炭素原子数１〜１２の直鎖状、分岐状もしくは環状のアルキレン基、−Ｏ−、−Ｓ−、−ＳＯ−、−ＳＯ_２−、−ＣＯ−、−ＣＯ−Ｏ−Ｚ−Ｏ−ＣＯ−（式中Ｚは脂肪族の２価基を表わす。）または、

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は１〜２０の整数、ｂは１〜２０００の整数、Ｒ_１０３、Ｒ_１０４は置換または無置換のアルキル基又はアリール基を表わす）を表わす。ここで、Ｒ_１０１とＲ_１０２、Ｒ_１０３とＲ_１０４は、それぞれ同一でも異なってもよい。）

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

式中、Ｒ_７，Ｒ_８は置換もしくは無置換のアリール基、Ａｒ_１，Ａｒ_２，Ａｒ_３は同一又は異なるアリレン基を表わす。Ｘ，ｋ，ｊおよびｎは、（Ｉ）式の場合と同じである。なお、（II）式は２つの共重合種が交互共重合体の形で記載されているが、ランダム共重合体でも構わない。

In the formula, R ₇ and R ₈ represent a substituted or unsubstituted aryl group, and Ar ₁ , Ar ₂ , and Ar ₃ represent the same or different arylene groups. X, k, j and n are the same as in the case of 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.

式中、Ｒ_９，Ｒ_１０は置換もしくは無置換のアリール基、Ａｒ_４，Ａｒ_５，Ａｒ_６は同一又は異なるアリレン基を表わす。Ｘ，ｋ，ｊおよびｎは、（Ｉ）式の場合と同じである。なお、（III）式は２つの共重合種が交互共重合体の形で記載されているが、ランダム共重合体でも構わない。

In the formula, R ₉ and R ₁₀ represent a substituted or unsubstituted aryl group, and Ar ₄ , Ar ₅ and Ar ₆ represent the same or different arylene groups. X, k, j and n are the same as in the case of 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.

式中、Ｒ_１１，Ｒ_１２は置換もしくは無置換のアリール基、Ａｒ_７，Ａｒ_８，Ａｒ_９は同一又は異なるアリレン基、ｐは１〜５の整数を表わす。Ｘ，ｋ，ｊおよびｎは、（Ｉ）式の場合と同じである。なお、（IV）式は２つの共重合種が交互共重合体の形で記載されているが、ランダム共重合体でも構わない。

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

式中、Ｒ_１３，Ｒ_１４は置換もしくは無置換のアリール基、Ａｒ_１０，Ａｒ_１１，Ａｒ_１２は同一又は異なるアリレン基、Ｘ_１，Ｘ_２は置換もしくは無置換のエチレン基、又は置換もしくは無置換のビニレン基を表わす。Ｘ，ｋ，ｊおよびｎは、（VI）式の場合と同じである。なお、（Ｖ）式は２つの共重合種が交互共重合体の形で記載されているが、ランダム共重合体でも構わない。

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

式中、Ｒ_１５，Ｒ_１６，Ｒ_１７，Ｒ_１８は置換もしくは無置換のアリール基、Ａｒ_１３，Ａｒ_１４，Ａｒ_１５，Ａｒ_１６は同一又は異なるアリレン基、Ｙ_１，Ｙ_２，Ｙ_３は単結合、置換もしくは無置換のアルキレン基、置換もしくは無置換のシクロアルキレン基、置換もしくは無置換のアルキレンエーテル基、酸素原子、硫黄原子、ビニレン基を表わし同一であっても異なってもよい。Ｘ，ｋ，ｊおよびｎは、（VI）式の場合と同じである。なお、（VI）式は２つの共重合種が交互共重合体の形で記載されているが、ランダム共重合体でも構わない。

In the formula, R ₁₅ , R ₁₆ , R ₁₇ and R ₁₈ are substituted or unsubstituted aryl groups, Ar ₁₃ , Ar ₁₄ , Ar ₁₅ and Ar ₁₆ are the same or different arylene groups, and Y ₁ , Y ₂ and Y ₃ are 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 may be the same or different. X, k, j and n are the same as in the case of the formula (VI). In the formula (VI), two copolymer species are described in the form of an alternating copolymer, but a random copolymer may be used.

式中、Ｒ_１９，Ｒ_２０は水素原子、置換もしくは無置換のアリール基を表わし，Ｒ_１９とＲ_２０は環を形成していてもよい。Ａｒ_１７，Ａｒ_１８，Ａｒ_１９は同一又は異なるアリレン基を表わす。Ｘ，ｋ，ｊおよびｎは、（Ｉ）式の場合と同じである。なお、（VII）式は２つの共重合種が交互共重合体の形で記載されているが、ランダム共重合体でも構わない。

In the formula, R ₁₉ and R _{20 each} represent a hydrogen atom or a substituted or unsubstituted aryl group, and R ₁₉ and R ₂₀ may form a ring. Ar ₁₇ , Ar ₁₈ and Ar ₁₉ represent the same or different arylene groups. X, k, j and n are the same as in the case of 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.

式中、Ｒ_２１は置換もしくは無置換のアリール基、Ａｒ_２０，Ａｒ_２１，Ａｒ_２２，Ａｒ_２３は同一又は異なるアリレン基を表わす。Ｘ，ｋ，ｊおよびｎは、（Ｉ）式の場合と同じである。なお、（VIII）式は２つの共重合種が交互共重合体の形で記載されているが、ランダム共重合体でも構わない。

In the formula, R ₂₁ represents a substituted or unsubstituted aryl group, and Ar ₂₀ , Ar ₂₁ , Ar ₂₂ , and Ar ₂₃ represent the same or different arylene groups. X, k, j and n are the same as in the case of 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.

式中、Ｒ_２２，Ｒ_２３，Ｒ_２４，Ｒ_２５は置換もしくは無置換のアリール基、Ａｒ_２４，Ａｒ_２５，Ａｒ_２６，Ａｒ_２７，Ａｒ_２８は同一又は異なるアリレン基を表わす。Ｘ，ｋ，ｊおよびｎは、（Ｉ）式の場合と同じである。なお、（IX）式は２つの共重合種が交互共重合体の形で記載されているが、ランダム共重合体でも構わない。

In the formula, R ₂₂ , R ₂₃ , R ₂₄ and R ₂₅ represent a substituted or unsubstituted aryl group, and Ar ₂₄ , Ar ₂₅ , Ar ₂₆ , Ar ₂₇ and Ar ₂₈ represent the same or different arylene groups. X, k, j and n are the same as in the case of 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.

式中、Ｒ_２６，Ｒ_２７は置換もしくは無置換のアリール基、Ａｒ_２９，Ａｒ_３０，Ａｒ_３１は同一又は異なるアリレン基を表わす。Ｘ，ｋ，ｊおよびｎは、（Ｉ）式の場合と同じである。なお、（Ｘ）式は２つの共重合種が交互共重合体の形で記載されているが、ランダム共重合体でも構わない。

In the formula, R ₂₆ and R ₂₇ represent a substituted or unsubstituted aryl group, and Ar ₂₉ , Ar ₃₀ and Ar ₃₁ represent the same or different arylene groups. X, k, j and n are the same as in the case of 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.

As the solvent used, tetrahydrofuran, dioxane, toluene, cyclohexanone, methyl ethyl ketone, xylene, acetone, diethyl ether, methyl ethyl ketone and the like are used. These may be used alone or in combination of two or more.
The coating solution for the charge transport layer is mainly composed of a charge transport material, a binder resin and a solvent, but if necessary, one or more plasticizers, leveling agents, antioxidants, light stabilizers, lubricants, etc. These additives may be added. In addition, since it is possible to suppress the detachment of the constituent material due to the regeneration process by performing the regeneration process by adding these charge transport materials and additives to the supercritical fluid and / or the subcritical fluid in advance, It is valid.

  As a method for coating the charge transport layer using the coating solution, known methods such as dip coating, spray coating, beat coating, nozzle coating, spinner coating, and ring coating can be used. The thickness of the charge transport layer is preferably 15 to 50 μm, more preferably 20 to 35 μm from the viewpoint of resolution and responsiveness. After coating the charge transport layer, it is dried by heating in an oven or the like. Although the drying temperature of a charge transport layer changes with kinds of solvent contained in the coating liquid of a charge transport layer, it is preferable that it is 80-150 degreeC, and 100-140 degreeC is more preferable.

<Photosensitive layer consisting of a single layer>
Next, the case where the photosensitive layer has a single layer structure will be described.
This is a photoreceptor in which the above-described charge generation material and charge transport material are dispersed and / or dissolved in a binder resin to realize a charge generation function and a charge transport function in one layer. In the photosensitive layer, a charge generating substance, a charge transporting substance and a binder resin are dissolved or dispersed in a solvent such as tetrahydrofuran, dioxane, dichloroethane, methyl ethyl ketone, cyclohexane, cyclohexanone, toluene, xylene, etc., and this is dip coated, spray coated, or bead coated. It can be formed by coating using a conventionally known method such as ring coating.

  The charge transport material preferably contains both a hole transport material and an electron transport material. Moreover, a plasticizer, a leveling agent, antioxidant, etc. can also be added as needed. Regarding the charge generating substance, charge transporting substance, binder resin, organic solvent and various additives used in the single photosensitive layer, any material contained in the above-described charge generating layer and charge transporting layer should be used. Is possible. As the binder resin, in addition to the binder resin previously mentioned in the charge transport layer, the binder resin mentioned in the charge generation layer may be mixed and used. The amount of the charge generating material with respect to 100 parts by weight of the binder resin is preferably 5 to 40 parts by weight, more preferably 10 to 30 parts by weight, and the amount of the charge transporting material is preferably 0 to 190 parts by weight, more preferably 50 to 50 parts by weight. 150 parts by weight. Moreover, 5-40 micrometers is suitable for the film thickness of a photosensitive layer, and 10-30 micrometers is more preferable.

  An undercoat layer can be provided between the conductive support and the photosensitive layer or the charge generation layer, which is effective. The undercoat layer is mainly composed of a binder resin. However, considering that the photosensitive layer is coated with a solvent on these resins, it is desirable that the resin be a resin having high solvent resistance with respect to a general organic solvent. . Examples of such resins include water-soluble resins such as polyvinyl alcohol, casein, and sodium polyacrylate, alcohol-soluble resins such as polyamide, copolymer nylon, and methoxymethylated nylon, polyurethane, melamine resin, phenol resin, and alkyd-melamine resin. , Isocyanates, epoxy resins, and the like, and cross-linkable resins that form a three-dimensional network structure. Among these, thermosetting resins are most suitable from the viewpoint of solvent resistance.

In addition, it is also possible to add a metal oxide filler that can be exemplified by titanium oxide, silica, alumina, zirconium oxide, tin oxide, indium oxide and the like to prevent moire and reduce residual potential, It is valid. Among these, titanium oxide that is effective for reducing residual potential, preventing moire, and reducing background contamination is preferably used. These fillers can also be subjected to a surface treatment, and for example, those treated with a silane coupling agent, a titanium coupling agent, a chromium coupling agent or the like can be used.
The coating liquid for these undercoat layers contains a binder resin or a solvent as a main component, but a filler such as a metal oxide, a dispersant, a catalyst, or the like may be added as necessary.

As a method of applying the undercoat layer using the coating solution, known methods such as dip coating, spray coating, beat coating, nozzle coating, spinner coating, ring coating and the like can be used. The thickness of the undercoat layer is preferably 0.1 to 20 μm, and more preferably 0.5 to 7 μm. After coating the undercoat layer, it is heated and dried in an oven or the like. Although the drying temperature of an undercoat layer changes with kinds of the solvent and thermosetting resin which are contained in the coating liquid of an undercoat layer, 80-160 degreeC is preferable and 100-140 degreeC is more preferable.
In addition, in the undercoat layer of the present invention, Al ₂ O ₃ is provided by anodization, organic substances such as polyparaxylylene (parylene), SiO ₂ , SnO ₂ , TiO ₂ , ITO, CeO ₂ Any known undercoat layer, such as those provided with an inorganic material such as a vacuum thin film forming method, can be used satisfactorily.

  It is also possible to provide an intermediate layer between the conductive support and the undercoat layer or between the undercoat layer and the charge generation layer. In the intermediate layer, a binder resin is generally used as a main component. As these resins, resins unnecessary for the solvent contained in the coating liquid laminated on the intermediate layer are preferable, and alcohol-soluble resins such as polyamide, alcohol-soluble nylon, water-soluble polyvinyl butyral, polyvinyl butyral, and polyvinyl alcohol, Thermosetting resin etc. are mentioned. As a method for forming the intermediate layer, generally used coating methods described for the undercoat layer and the photosensitive layer are employed. In addition, 0.05-2 micrometers is suitable for the thickness of an intermediate | middle layer.

It is also possible to provide a protective layer on the outermost surface of the photoreceptor. The protective layer is formed for the purpose of increasing the wear resistance of the photoreceptor, and is used for the purpose of increasing the wear resistance. In the present invention, the amount of wear of the photoconductor is reduced by the formation of the protective layer. Therefore, even if the photoconductor has reached the end of its life, the thickness of the photoconductor should be maintained by having the protective layer. Since the reproduction effect by the reproduction processing of the present invention is remarkably enhanced, it is particularly effective.
When carrying out the regeneration treatment of the present invention, it is possible to form any protective layer on the outermost surface of the photoreceptor, which is effective, but as a particularly effective protective layer, polymer charge transport to the binder resin of the protective layer is effective. Examples include using a substance, dispersing fillers and fine particles in the protective layer, and using a curable resin by heat curing or ultraviolet curing.

Since the protective layer using the polymer charge transport material does not contain a low molecular charge transport material, it is effective in improving the wear resistance. In addition, the absence of a low-molecular charge transport material is a suitable protective layer in the present invention because the elimination of the charge transport material is reduced during the regeneration process. As the polymer charge transport material used in the protective layer, the polymer charge transport material used in the above-described charge transport layer can be used, which is effective.
It is also possible to contain a low molecular charge transport material. Furthermore, you may add additives, such as a plasticizer, a leveling agent, antioxidant, a light stabilizer, and a lubricant, as needed. The solvent used for coating the protective layer using the polymer charge transport material can be the solvent used in the charge transport layer, and can be used alone or in combination of two or more. Also good.

  As a method for coating the protective layer using the coating solution, known methods such as dip coating, spray coating, beat coating, nozzle coating, spinner coating, ring coating, and the like can be used. Although the film thickness of a protective layer is based also on an abrasion rate, 1-20 micrometers is preferable and 2-10 micrometers is more preferable. After coating, it is heated and dried in an oven or the like. Although drying temperature changes with kinds of solvent contained in a protective layer coating liquid, it is preferable that it is 80-150 degreeC, and 100-140 degreeC is further more preferable.

  The protective layer in which the filler and fine particles are dispersed contains a filler having a hardness higher than that of the binder resin, thereby improving the wear resistance. The filler is classified into an organic filler and an inorganic filler, but both can be used effectively. However, an inorganic filler having a higher filler hardness tends to have higher wear resistance. Examples of inorganic fillers include metal powders such as copper, tin, aluminum and indium, alumina, silica, tin oxide, zinc oxide, titanium oxide, indium oxide, antimony oxide, bismuth oxide, tin oxide doped with antimony and tin. Examples thereof include metal oxides such as doped indium oxide. Among these, metal oxides are preferably used from the viewpoints of wear resistance, film-forming properties, and light transmittance, and alumina, silica, and titanium oxide are particularly preferable. Further, these fillers may be subjected to a surface treatment, which is effective.

  Although the hardness is not as high as that of the inorganic filler, there is a method in which the friction coefficient on the surface of the photoreceptor is reduced by dispersing fine particles having lubricity, thereby improving the wear resistance. As these fine particles, organic fillers are effective, and examples thereof include fluorine resin fine particles such as polytetrafluoroethylene, silicone resin fine particles, and acrylic-modified polyorganosiloxane fine particles.

  The average primary particle size of the filler and fine particles is preferably 0.01 to 0.9 μm, more preferably 0.1 to 0.5 μm. If the average primary particle size of the filler is too large, the irregularities on the surface of the photoreceptor become large, which may cause cleaning failure. On the other hand, if the filler is too small, the filler tends to agglomerate or the residual potential may increase due to an increase in surface area.

The protective layer in which fillers and fine particles are dispersed can contain a charge transport material, which is effective in reducing residual potential and improving resolution and gradation. As the charge transport material, conventionally known materials can be used, and examples thereof include materials used in the charge transport layer. Furthermore, you may add additives, such as a plasticizer, a leveling agent, antioxidant, a light stabilizer, and a lubricant, as needed.
As the binder resin, a binder resin used in a photosensitive layer or a charge transport layer can be used. Of these, polycarbonate and polyarylate used for the charge transport layer are particularly effective. In addition, it is possible to use a polymer charge transport material, which is particularly effective since it can realize further improvement in wear resistance. As the polymer charge transport material, the above-described materials can be used as they are.
As the solvent used for coating the protective layer, the solvent used in the charge transport layer can be used, and may be used alone or in combination of two or more.

  As a method for coating the protective layer using the coating solution, known methods such as dip coating, spray coating, beat coating, nozzle coating, spinner coating, ring coating, and the like can be used. The thickness of the protective layer is preferably 1 to 10 μm, more preferably 2 to 7 μm, although it depends on the wear rate. After coating, it is heated and dried in an oven or the like. Although drying temperature changes with kinds of solvent contained in a protective layer coating liquid, it is preferable that it is 80-160 degreeC, and 100-150 degreeC is further more preferable.

The crosslinkable protective layer that is cross-linked by a method such as heat curing or ultraviolet curing uses a reactive monomer having a plurality of crosslinkable functional groups in one molecule and uses light or heat energy for forming a cross-linked structure. To cause a cross-linking reaction to form a three-dimensional network structure. This network structure functions as a binder resin and exhibits high wear resistance.
As the reactive monomer, it is preferable to use a monomer having a charge transporting ability in whole or in part. Suitable examples of the monomer having charge transporting ability include reactive monomers having a triarylamine structure. By using such a monomer, a charge transport site is formed in the network structure, and it is possible to achieve both wear resistance and electrostatic characteristics. In addition, the protective 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. Therefore, in order to prevent this, even if a protective layer is formed in a laminated structure, a protective layer of a low molecular dispersion polymer is used for the lower layer (photosensitive layer side), and a protective layer having a crosslinked structure is formed on the upper layer (surface side). good.

  Among the cross-linked protective layers, in particular, a protective layer having a cross-linked structure obtained by curing a tri- or higher functional radical polymerizable monomer has developed a three-dimensional network structure, and has a high hardness and high elasticity with a very high cross-linking density. From the viewpoint of obtaining a surface layer, uniform and high smoothness, and achieving high wear resistance and scratch resistance, it is preferably used.

  In the formation of the crosslinkable protective layer, by making the crosslinkable protective layer insoluble in the organic solvent, particularly dramatic wear resistance is exhibited. The crosslinked protective layer of the present invention is formed by curing a tri- or higher functional radical polymerizable monomer having no charge transport structure and a radical polymerizable compound having a monofunctional charge transport structure. Dimensional network structure develops and has a high crosslinking density, but contains other than the above components (for example, mono- or bifunctional monomers, polymer binders, antioxidants, leveling agents, plasticizers and other additives and lower layers) Depending on the dissolved components) and curing conditions, the cross-linking density may be locally dilute or may be formed as an aggregate of minute cured products cross-linked at high density. Such a crosslinkable protective layer has a low bonding strength between cured products and is soluble in organic solvents, and is repeatedly used in the electrophotographic process. Detachment easily occurs. By making the crosslinkable protective layer insoluble in an organic solvent, the original three-dimensional network structure develops and has a high degree of crosslinking, and the chain reaction proceeds in a wide range and the cured product has a high molecular weight. A dramatic improvement in wear resistance is achieved.

Examples of the trifunctional or higher functional monomer having no charge transporting structure include a hole transporting structure such as triarylamine, hydrazone, pyrazoline, carbazole, condensed polycyclic quinone, diphenoquinone, cyano group, nitro group, and the like. A monomer having no electron transport structure such as an electron-withdrawing aromatic ring and having three or more radically polymerizable functional groups.
The radical polymerizable functional group can be appropriately selected and used as long as it has a carbon-carbon double bond and can be radically polymerized.
Examples of the radical polymerizable functional group include a 1-substituted ethylene functional group and a 1,1-substituted ethylene functional group shown below.

Examples of the 1-substituted ethylene functional group include functional groups represented by the following formulas.
CH ₂ = CH—X ₁ −... Formula 10
However, in the formula 10, X ₁ is an optionally substituted phenylene group, an arylene group, an alkenylene group which may have a substituent such as a naphthylene group, -CO- group, -COO- group, -CON _{(R 10)} - group _{(R 10} is hydrogen, alkyl group such as a methyl group, an ethyl group, a benzyl group, naphthylmethyl group, an aralkyl group such as a phenethyl group, a phenyl group, an aryl group such as phenyl or naphthyl 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.

Examples of the 1,1-substituted ethylene functional group include functional groups represented by the following formulas.
_{CH 2 = C (Y) -X} 2 - ···· formula 11
However, in said Formula 11, Y is an alkyl group which may have a substituent, an aralkyl group which may have a substituent, a phenyl group which may have a substituent, a naphthyl group, etc. Aryl group, halogen atom, cyano group, nitro group, methoxy group, alkoxy group such as methoxy group, -COOR ₁₁ group (R ₁₁ is a hydrogen atom, an optionally substituted methyl group, ethyl group, etc. An alkyl 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 a -CONR ₁₂ R ₁₃ group (R ₁₂ And R ₁₃ represents a hydrogen atom, an alkyl group such as an optionally substituted methyl group or an ethyl group, an aralkyl group such as an optionally substituted benzyl group, a naphthylmethyl group, or an arenyl group such as a phenethyl group. Kill group or substituent a phenyl group which may have a, an aryl group such as a naphthyl group, a mutually identical or may be different.). In addition, X ₂ and X ₁ of the formula 10 Represents the same substituent, a single bond, and an alkylene group, provided that at least one of Y and X ₂ is at least an oxycarbonyl group, a cyano group, an alkenylene group, or an aromatic ring.
Specific examples of the functional group include an α-acryloyloxy chloride group, a methacryloyloxy group, an α-cyanoethylene group, an α-cyanoacryloyloxy group, an α-cyanophenylene group, and a methacryloylamino group.
Examples of the substituent further substituted with the substituent for X ₁ , X ₂ and Y include, for example, a halogen atom, a nitro group, a cyano group, a methyl group, an alkyl group such as an ethyl group, a methoxy group, an ethoxy group, and the like. Examples thereof include aryloxy groups such as alkoxy groups and phenoxy groups, aryl groups such as phenyl groups and naphthyl groups, aralkyl groups such as benzyl groups and phenethyl groups.

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

  As a specific tri- or more functional radical polymerizable monomer having no charge transport structure, a commonly used substance can be appropriately selected and used. For example, trimethylolpropane triacrylate (TMPTA), trimethylol Methylolpropane trimethacrylate, trimethylolpropane alkylene modified triacrylate, trimethylolpropane ethyleneoxy modified (hereinafter EO modified) triacrylate, trimethylolpropane propyleneoxy modified (hereinafter PO modified) triacrylate, trimethylolpropane caprolactone modified triacrylate, tri Methylolpropane alkylene-modified trimethacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate (PETTA), glycerol triacrylate Glycerol, epichlorohydrin modified (hereinafter ECH modified) triacrylate, glycerol EO modified triacrylate, glycerol PO modified triacrylate, tris (acryloxyethyl) isocyanurate, dipentaerythritol hexaacrylate (DPHA), dipentaerythritol caprolactone Modified hexaacrylate, dipentaerythritol hydroxypentaacrylate, alkylated dipentaerythritol pentaacrylate, alkylated dipentaerythritol tetraacrylate, alkylated dipentaerythritol triacrylate, dimethylolpropane tetraacrylate (DTMPTA), pentaerythritol ethoxytetraacrylate, Phosphoric acid EO-modified triacrylate, 2,2, , 5, - tetramethyl-hydroxymethyl cyclopentanone tetraacrylate, and the like. These may be used individually by 1 type and may combine 2 or more types.

The trifunctional or higher functional radical polymerizable monomer having no charge transporting structure has a molecular weight ratio (molecular weight / functional group number) with respect to the number of functional groups in the monomer in order to form a dense crosslink in the crosslinkable protective layer. ) Is preferably 250 or less. If this ratio is greater than 250, the crosslinked protective layer is soft and wear resistance may be somewhat lowered. Therefore, among monomers exemplified above, monomers having a modifying group such as EO, PO, caprolactone, etc. It may be difficult to use a compound having a long modifying group alone.
The proportion of the trifunctional or higher functional radical polymerizable monomer having no charge transporting structure is preferably 20 to 80% by mass, and more preferably 30 to 70% by mass with respect to the total amount of the crosslinked protective layer. If the component ratio is less than 20% by mass, the three-dimensional crosslink density of the crosslinkable protective layer is small, and it may be difficult to achieve a dramatic improvement in wear resistance as compared with the case of using a conventional thermoplastic binder resin. On the other hand, if it exceeds 80% by mass, the content of the charge transporting compound may be lowered, and the electrical characteristics may be deteriorated. The electrical properties and abrasion resistance required vary depending on the process used, and the thickness of the crosslinked protective layer of the electrostatic latent image carrier varies accordingly. The range of 30-70 mass% is the most preferable.

Examples of the radically polymerizable compound having a monofunctional charge transporting structure include a hole transporting structure such as triarylamine, hydrazone, pyrazoline, and carbazole, condensed polycyclic quinone, diphenoquinone, cyano group, and nitro group. A compound having an electron transport structure such as an electron-withdrawing aromatic ring and having one radical polymerizable functional group.
Examples of the radical polymerizable functional group include those shown in the above radical polymerizable monomer, and acryloyloxy group and methacryloyloxy group are particularly preferable.
Further, as the charge transporting structure, a triarylamine structure is preferable, and in particular, a compound represented by the following structural formula (1) or (2) is preferable because electrical characteristics such as sensitivity and residual potential are favorably sustained. .

ただし、前記構造式（１）及び（２）中、Ｒ_１は水素原子、ハロゲン原子、置換基を有してもよいアルキル基、置換基を有してもよいアラルキル基、置換基を有してもよいアリール基、シアノ基、ニトロ基、アルコキシ基、−ＣＯＯＲ_７（ただし、Ｒ_７は水素原子、置換基を有してもよいアルキル基、置換基を有してもよいアラルキル基又は置換基を有してもよいアリール基）、ハロゲン化カルボニル基若しくはＣＯＮＲ_８Ｒ_９（ただし、Ｒ_８及びＲ_９は水素原子、ハロゲン原子、置換基を有してもよいアルキル基、置換基を有してもよいアラルキル基又は置換基を有してもよいアリール基を示し、互いに同一であっても異なっていてもよい）を表わし、Ａｒ_１、Ａｒ_２は置換もしくは無置換のアリーレン基を表わし、同一であっても異なってもよい。Ａｒ_３、Ａｒ_４は置換もしくは無置換のアリール基を表わし、同一であっても異なってもよい。Ｘは単結合、置換もしくは無置換のアルキレン基、置換もしくは無置換のシクロアルキレン基、置換もしくは無置換のアルキレンエーテル基、酸素原子、硫黄原子、ビニレン基を表わす。Ｚは置換もしくは無置換のアルキレン基、置換もしくは無置換のアルキレンエーテル２価基、アルキレンオキシカルボニル２価基を表わす。ｍ、ｎは０〜３の整数を表わす。

In the Structural Formula (1) and (2), R ₁ has a hydrogen atom, a halogen atom, an optionally substituted alkyl group, an optionally substituted aralkyl group, a substituent Aryl group, cyano group, nitro group, alkoxy group, —COOR ₇ (wherein R ₇ is a hydrogen atom, an alkyl group which may have a substituent, an aralkyl group or a substituent which may have a substituent) Aryl group which may have a group), carbonyl halide group or CONR ₈ R ₉ (wherein R ₈ and R ₉ have a hydrogen atom, a halogen atom, an alkyl group which may have a substituent, or a substituent. Represents an aralkyl group which may be substituted or an aryl group which may have a substituent, which may be the same or different from each other, and Ar ₁ and Ar ₂ represent a substituted or unsubstituted arylene group. The same 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.

In the structural formulas (1) and (2), examples of the alkyl group in the substituent of R ₁ include a methyl group, an ethyl group, and a propyl group. Examples of the alkoxy group include a methoxy group, An ethoxy group, a propoxy group, etc. are mentioned. These include halogen atoms, nitro groups, cyano groups, alkyl groups such as methyl groups and ethyl groups, alkoxy groups such as methoxy groups and ethoxy groups, aryloxy groups such as phenoxy groups, aryl groups such as phenyl groups and naphthyl groups, It may be substituted with an aralkyl group such as a benzyl group or a phenethyl group.
Among the substituents for R ₁ , a hydrogen atom and a methyl group are preferable.

Examples of the aryl group of Ar ₃ and Ar ₄ include a condensed polycyclic hydrocarbon group, a non-condensed 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-condensed cyclic hydrocarbon group include monovalent groups of monocyclic hydrocarbon compounds such as benzene, diphenyl ether, polyethylene diphenyl ether, diphenyl thioether and diphenyl sulfone, biphenyl, polyphenyl, diphenylalkane, diphenylalkene, diphenylalkyne, Monovalent groups of non-condensed polycyclic hydrocarbon compounds such as triphenylmethane, distyrylbenzene, 1,1-diphenylcycloalkane, polyphenylalkane and polyphenylalkene, and ring-assembled hydrocarbons such as 9,9-diphenylfluorene The monovalent group of a compound is mentioned.
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, etc.
(2) Alkyl groups, preferably C ₁ -C _12, especially C ₁ -C ₈ , more preferably C ₁ -C ₄ linear or branched alkyl groups, further including fluorine atoms , a hydroxyl group, a cyano _group, an alkoxy group of C 1 -C _4, a phenyl group or a halogen _atom, which may have a phenyl group substituted by an alkoxy group C 1 -C ₄ alkyl or _C 1 -C ₄ Good. Specifically, methyl group, ethyl group, n-butyl group, i-propyl group, t-butyl group, s-butyl group, n-propyl group, trifluoromethyl group, 2-hydroxyethyl group, 2-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 , A trifluoromethoxy group, and the like.
(4) an aryloxy group, phenyl and the aryl group group, a naphthyl group, an alkoxy group of C ₁ -C _4, alkyl group of C ₁ -C _4, also contain a halogen atom as a substituent Good. Specific examples include phenoxy group, 1-naphthyloxy group, 2-naphthyloxy group, 4-methoxyphenoxy group, 4-methylphenoxy group, and the like.
(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) Group represented by the following general formula

ただし、前記一般式中、Ｒ_３及びＲ_４は各々独立に水素原子、アルキル基、またはアリール基を表わす。前記アリール基としては、例えば、フェニル基、ビフェニル基又はナフチル基が挙げられ、これらはＣ_１〜Ｃ_４のアルコキシ基、Ｃ_１〜Ｃ_４のアルキル基またはハロゲン原子を置換基として含有してもよい。Ｒ_３及びＲ_４は共同で環を形成してもよい。
具体的には、アミノ基、ジエチルアミノ基、Ｎ−メチル−Ｎ−フェニルアミノ基、Ｎ，Ｎ−ジフェニルアミノ基、Ｎ，Ｎ−ジ（トリール）アミノ基、ジベンジルアミノ基、ピペリジノ基、モルホリノ基、ピロリジノ基、などが挙げられる。
（７）メチレンジオキシ基等のアルキレンジオキシ基、又はメチレンジチオ基等のアルキレンジチオ基、など。
（８）置換又は無置換のスチリル基、置換又は無置換のβ−フェニルスチリル基、ジフェニルアミノフェニル基、ジトリルアミノフェニル基、など。

However, represented in the formula, R ₃ and R ₄ each independently represent a hydrogen atom, an alkyl group or an aryl group. Examples of the aryl group include a phenyl group, biphenyl group or a naphthyl group and the like, also contain these alkoxy groups C ₁ -C _4, alkyl group, or a halogen atom C ₁ -C ₄ as a substituent Good. R ₃ and R ₄ may form a ring together.
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 , A pyrrolidino group, and the like.
(7) An alkylenedioxy group such as a methylenedioxy group or an alkylenedithio group such as a methylenedithio group.
(8) A substituted or unsubstituted styryl group, a substituted or unsubstituted β-phenylstyryl group, a diphenylaminophenyl group, a ditolylaminophenyl group, and the like.

Examples of the substituted or unsubstituted alkylene group for X 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 in the alkylene group, a hydroxyl group, a cyano _group, C 1 -C ₄ alkoxy group, a phenyl group or a halogen _atom, phenyl substituted with alkyl group or a _C 1 -C ₄ alkoxy group C 1 -C ₄ It may have a group.
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-ethoxy. Examples include ethylene 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, which include a fluorine atom, a hydroxyl group, a 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. You may have.
The vinylene group is represented by the following general formula.

ただし、前記一般式中、Ｒ_５は水素、アルキル基（前記（２）で定義されるアルキル基と同じ）、アリール基（前記Ａｒ_３、Ａｒ_４で表わされるアリール基と同じ）、ａは１または２、ｂは１〜３を表わす。

In the general formula, _{R 5} is hydrogen, an alkyl group (the (same as alkyl group, as defined 2)), an aryl group (same as the aryl group represented by _Ar 3, Ar _4), a is 1 Or 2, b represents 1-3.

Examples of Z include a substituted or unsubstituted alkylene group, a substituted or unsubstituted alkylene ether divalent group, and 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.

  Furthermore, preferred examples of the radical polymerizable compound having a monofunctional charge transporting structure include compounds represented by the following structural formula (3).

ただし、前記構造式（３）中、ｏ、ｐ、ｑはそれぞれ０又は１の整数、Ｒａは水素原子、メチル基を表わし、Ｒｂ、Ｒｃは水素原子以外の置換基で炭素数１〜６のアルキル基を表わし、複数の場合は異なっても良い。ｓ、ｔは０〜３の整数を表わす。Ｚａは単結合、メチレン基、エチレン基、下記一般式（４）で表わされる基を表わす。

However, in the structural formula (3), o, p and q are each an integer of 0 or 1, Ra represents a hydrogen atom or a methyl group, and Rb and Rc are substituents other than a hydrogen atom and have 1 to 6 carbon atoms. Represents an alkyl group, and a plurality of them 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 group represented by the following general formula (4).

  The compound represented by the general formula (4) is preferably a compound having at least one of a methyl group and an ethyl group as a substituent for Rb and Rc.

  Since the radically polymerizable compound having the monofunctional charge transporting structure represented by the structural formulas (1) to (3), particularly (3), is polymerized because the carbon-carbon double bond is opened on both sides, In a polymer that does not become a terminal structure, is incorporated in a chain polymer, and is crosslinked by polymerization with a radically polymerizable monomer having three or more functions, it exists in the main chain of the polymer, and the main chain- Present in the cross-linked chain between the main chains (this cross-linked chain includes an inter-molecular cross-linked chain between one polymer and another polymer, a site with a main chain folded in one polymer, and a main chain. There are intramolecular cross-linked chains that are cross-linked with other sites derived from the polymerized monomer at positions away from this in the chain), but they are also present in the cross-linked chain even if they are present in the main chain Even if the triarylamine structure suspended from the chain moiety is Has at least three aryl groups arranged in the bulky and is bulky, but is not directly bonded to the chain part, but is suspended from the chain part via a carbonyl group etc. Since these triarylamine structures can be arranged in the polymer in a space that is reasonably adjacent to each other, there is little structural distortion in the molecule, and the electrophotographic electrostatic latent image carrier In the case of a surface layer, it is presumed that an intramolecular structure that is relatively free from interruption of the charge transport pathway can be adopted.

  Specific examples of the radical polymerizable compound having a monofunctional charge transporting structure are shown below, but are not limited to the compounds having these structures. These polymerizable compounds themselves are conventionally known (see, for example, JP-A-2006-15496, JP-A-2006-221115, JP-A-2006-221157, etc.).

The radically polymerizable compound having the monofunctional charge transport structure is important for imparting the charge transport performance of the cross-linked protective layer.
The content of this component is preferably 20 to 80% by mass with respect to the crosslinkable protective layer, and the required electric characteristics and wear resistance differ depending on the process used. Although the thickness of the cross-linked protective layer of the body is also different, it cannot be generally stated, but 30 to 70% by mass is more preferable in consideration of the balance of both characteristics. If this component is less than 20% by mass, the charge transport performance of the crosslinkable protective layer cannot be maintained sufficiently, and repeated use may cause deterioration of electrical characteristics such as a decrease in sensitivity and an increase in residual potential. On the other hand, if it exceeds 80% by mass, the content of the trifunctional monomer having no charge transporting structure is lowered, and the crosslink bond density is lowered and high wear resistance may not be exhibited.

  The crosslinked protective layer is obtained by curing at least a trifunctional or higher-functional radical polymerizable monomer having no charge transport structure and a radical polymerizable compound having a monofunctional charge transport structure. Monofunctional and bifunctional radically polymerizable monomers, functional monomers, and radically polymerizable oligomers are used in combination for the purpose of imparting functions such as viscosity adjustment at the time, stress relaxation of the cross-linkable protective layer, low surface energy and friction coefficient reduction. be able to. As these radically polymerizable monomers and oligomers, commonly known monomers can be used.

The crosslinkable protective layer may contain a polymerization initiator such as a thermal polymerization initiator or a photopolymerization initiator in the crosslinkable protective layer coating liquid in order to efficiently advance the curing reaction as necessary. good.
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-butyl Peroxycyclohexyl) propane, peroxide initiators, azobisisobutyronitrile, azobiscyclohexanecarbonitrile, methyl azobisisobutyrate, azobisisobutylamidine hydrochloride, 4,4′-azobis-4-cyanovaleric acid An azo-based initiator such as

  Examples of the photopolymerization initiator include diethoxyacetophenone, 2,2-dimethoxy-1,2-diphenylethane-1-one, 1-hydroxy-cyclohexyl-phenyl-ketone, and 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 Acetophenone-based or ketal-based photopolymerization of 2-methyl-2-morpholino (4-methylthiophenyl) propan-1-one, 1-phenyl-1,2-propanedione-2- (o-ethoxycarbonyl) oxime, etc. Initiator, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isobu Benzoin ether photopolymerization initiators such as ether, benzoin isopropyl ether, benzophenone, 4-hydroxybenzophenone, methyl o-benzoylbenzoate, 2-benzoylnaphthalene, 4-benzoylbiphenyl, 4-benzoylphenyl ether, acrylated benzophenone, Benzophenone photopolymerization initiators such as 1,4-benzoylbenzene, thioxanthone such as 2-isopropylthioxanthone, 2-chlorothioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, 2,4-dichlorothioxanthone, etc. -Based photopolymerization initiator, ethyl anthraquinone, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, 2,4,6-trimethylbenzoylphenylethoxyphosphine Oxide, bis (2,4,6-trimethylbenzoyl) phenylphosphine oxide, bis (2,4-dimethoxybenzoyl) -2,4,4-trimethylpentylphosphine oxide, methylphenylglyoxyester, 9,10-phenanthrene, Other photopolymerization initiators such as acridine compounds, triazine compounds, and imidazole compounds can be mentioned.

  A substance having a photopolymerization promoting effect can also be used. Examples of the substance having a photopolymerization promoting effect include triethanolamine, methyldiethanolamine, ethyl 4-dimethylaminobenzoate, isoamyl 4-dimethylaminobenzoate, (2-dimethylamino) ethyl benzoate, 4,4 ′. -Dimethylaminobenzophenone, etc. These may be used alone or in combination with the photopolymerization initiator.

  The said polymerization initiator may be used individually by 1 type, and 2 or more types may be mixed and used for it. As content of the said polymerization initiator, it is preferable that it is 0.5-40 weight part with respect to 100 weight part of total content which has radical polymerizability, and it is more preferable that it is 1-20 weight part.

Furthermore, the crosslinkable protective layer includes, as necessary, a plasticizer (for the purpose of stress relaxation and adhesion improvement), a leveling agent, a low molecular charge substance having no radical reactivity, and the like. These additives may be included.
These additives can be appropriately selected from commonly used substances, and examples of the plasticizer include dibutyl phthalate and dioctyl phthalate. Examples of the leveling agent include: , Silicone oils such as dimethyl silicone oil and methylphenyl silicone oil, and polymers or oligomers having a perfluoroalkyl group in the side chain.
As content of the said plasticizer, it is preferable that it is 20 mass% or less with respect to the total solid of a coating liquid, and it is more preferable that it is 10 mass% or less. As content of the said leveling agent, it is preferable that it is 3 mass% or less with respect to the total solid of a coating liquid.

The crosslinkable protective layer includes a coating solution containing at least a trifunctional or higher functional radical polymerizable monomer having no charge transport structure and a radical polymerizable compound having a monofunctional charge transport structure. Alternatively, it is formed by applying and curing on the charge transport layer. When the radically polymerizable monomer is a liquid, the coating liquid can be applied by dissolving other components in the liquid, but if necessary, it is diluted with a solvent and applied.
Examples of the solvent 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. Ethers, halogens such as dichloromethane, dichloroethane, trichloroethane and chlorobenzene, aromatics such as benzene, toluene and xylene, cellosolves such as methyl cellosolve, ethyl cellosolve and cellosolve acetate. These may be used individually by 1 type, and 2 or more types may be mixed and used for them. There is no restriction | limiting in particular as a dilution rate by the said solvent, According to the solubility of a composition, the coating method, and the target film thickness, it can change suitably.
As the coating method, for example, a dip coating method, spray coating, bead coating, ring coating method, or the like can be used. However, a method of reducing the contact time with the solvent is preferable, and specifically, a spray coating method and a ring coating method in which the amount of coating liquid is regulated are more preferable. Also, in order to suppress the amount of the lower layer component mixed in, a polymer charge transport material is used as the charge transport layer, and a crosslinkable protective layer is applied between the photosensitive layer (or charge transport layer) and the crosslinkable protective layer. It is also effective to provide an intermediate layer insoluble in the solvent.

  The thickness of the crosslinkable protective layer is preferably 1 to 10 μm or less, and more preferably 2 to 8 μm or less. If it is thicker than 10 μm, cracks and film peeling may easily occur. When the thickness is 8 μm or less, the margin is further improved, so that the crosslinking density can be increased, and further, material selection and setting of curing conditions can be set to enhance wear resistance. On the other hand, the radical polymerization reaction is susceptible to oxygen inhibition, that is, the surface in contact with the air may not be cross-linked or become uneven due to the influence of radical trapping by oxygen. This effect appears remarkably when the surface layer is less than 1 μm, and the crosslinkable protective layer having a thickness less than this thickness may cause a decrease in wear resistance or uneven wear. In addition, when the crosslinkable protective layer is applied, the lower charge transport layer component is mixed.In particular, if the coating thickness of the crosslinkable protective layer is thin, the contaminants spread throughout the layer, inhibiting the curing reaction and reducing the crosslink density. May cause reduction. For these reasons, the cross-linkable protective layer has good wear resistance and scratch resistance at a film thickness of 1 μm or more. However, if it is locally scraped up to the lower charge transport layer in repeated use, the wear of that part will occur. And the density unevenness of the halftone image is likely to occur due to chargeability and sensitivity fluctuations. Therefore, it is preferable that the film thickness of the crosslinkable protective layer is 2 μm or more for a longer life and higher image quality.

The crosslinkable protective layer is formed by applying a crosslinkable protective layer coating solution and then curing by applying energy from the outside. Examples of the external energy include heat, light, and radiation.
Examples of the method of applying heat energy include a method of heating from the coating surface side or the support side using a gas such as air or nitrogen, steam, various heat media, infrared rays, or electromagnetic waves.
In the case of thermosetting, the heating temperature is preferably 100 ° C. or higher, more preferably 170 ° C. or lower. Below 100 ° C., the reaction rate is slow and the curing reaction may not be completed completely. At a high temperature exceeding 170 ° C., the curing reaction proceeds non-uniformly, and large strains, a large number of unreacted residues, and reaction termination terminals may be generated in the crosslinked protective layer. In order to advance the curing reaction uniformly, a method of heating at a relatively low temperature of less than 100 ° C. and then heating to 100 ° C. or more to complete the reaction is also preferable.
Examples of the energy of light include UV irradiation light sources such as high-pressure mercury lamps and metal halide lamps that have an emission wavelength mainly in the ultraviolet region, but the visible light source can be used in accordance with the absorption wavelength of radical polymerizable substances and photopolymerization initiators. Selection is also possible.
As irradiation light quantity, 50-1000 mW / cm < ² > or less is preferable. Is less than 50 mW / cm ² may take time for the curing reaction, 1000 mW / progression of stronger reaction than cm ² becomes non-uniform, local wrinkles may occur in the crosslinked protective layer surface, a large number of unreacted Residues, reaction termination ends may occur. In addition, the internal stress increases due to rapid crosslinking, which may cause cracks and film peeling. It is more preferable to control the drum temperature so as not to exceed 50 ° C.
Examples of radiation energy include those using electron beams.
Among these energies, it is preferable to use heat or light energy because of easy reaction rate control and simple apparatus.

In the above photoreceptor, for the purpose of preventing a decrease in sensitivity and an increase in residual potential, at least one layer such as a charge generation layer, a charge transport layer, an undercoat layer, an intermediate layer, a protective layer, an antioxidant, a plasticizer, Lubricants, UV absorbers, low molecular charge transport materials and leveling agents can be added. These additives and the like are added to the supercritical fluid and / or subcritical fluid in advance, so that when the photoconductor is brought into contact with the supercritical fluid and / or subcritical fluid, the additive is added. This is effective because it is possible to prevent detachment from the layer. Examples of these additives are shown below, but are not limited thereto.
Examples of the antioxidant that can be added to each layer include, but are not limited to, the following.

(A) Phenol compound 2,6-di-t-butyl-p-cresol, butylated hydroxyanisole, 2,6-di-t-butyl-4-ethylphenol, n-octadecyl-3- (4′- Hydroxy-3 ', 5'-di-t-butylphenol), 2,2'-methylenebis (4-methyl-6-t-butylphenol), 2,2'-methylenebis (4-ethyl-6-t-) Butylphenol), 4,4′-thiobis (3-methyl-6-tert-butylphenol), 4,4′-butylidenebis (3-methyl-6-tert-butylphenol), 1,1,3-tris (2-methyl) -4-hydroxy-5-tert-butylphenyl) butane, 1,3,5-trimethyl-2,4,6-tris (3,5-di-tert-butyl-4-hydroxybenzyl) benzene, tetrakis [meth -3- (3 ′, 5′-di-t-butyl-4′-hydroxyphenyl) propionate] methane, bis [3,3′-bis (4′-hydroxy-3′-t-butylphenyl) buty Rick acid] glycol ester, tocopherols and the like.
(B) Paraphenylenediamines N-phenyl-N′-isopropyl-p-phenylenediamine, N, N′-di-s-butyl-p-phenylenediamine, N-phenyl-Ns-butyl-p-phenylene Diamine, N, N′-diisopropyl-p-phenylenediamine, N, N′-dimethyl-N, N ′
-Di-t-butyl-p-phenylenediamine and the like.
(C) Hydroquinones 2,5-di-t-octylhydroquinone, 2,6-didodecylhydroquinone, 2-dodecylhydroquinone, 2-dodecyl-5-chlorohydroquinone, 2-t-octyl-5-methylhydroquinone, 2 -(2-octadecenyl) -5-methylhydroquinone and the like.
(D) Organic sulfur compounds dilauryl-3,3′-thiodipropionate, distearyl-3,3′-thiodipropionate, ditetradecyl-3,3′-thiodipropionate, and the like.
(E) Organic phosphorus compounds Triphenylphosphine, tri (nonylphenyl) phosphine, tri (dinonylphenyl) phosphine, tricresylphosphine, tri (2,4-dibutylphenoxy) phosphine and the like.

Examples of the plasticizer that can be added to each layer include, but are not limited to, the following.
(A) Phosphate ester plasticizer Triphenyl phosphate, tricresyl phosphate, trioctyl phosphate, octyl diphenyl phosphate, trichloroethyl phosphate, cresyl diphenyl phosphate, tributyl phosphate, tri (2-ethylhexyl) phosphate , Triphenyl phosphate and the like.
(B) Phthalate ester plasticizers Dimethyl phthalate, diethyl phthalate, diisobutyl phthalate, dibutyl phthalate, diheptyl phthalate, di (2-ethylhexyl) phthalate, diisooctyl phthalate, di-n-octyl phthalate, Dinonyl phthalate, diisononyl phthalate, diisodecyl phthalate, diundecyl phthalate, ditridecyl phthalate, dicyclohexyl phthalate, butyl benzyl phthalate, butyl lauryl phthalate, methyl oleyl phthalate, octyl decyl phthalate, dibutyl fumarate, fumaric acid Dioctyl etc.
(C) Aromatic carboxylic acid ester plasticizers Trioctyl trimellitic acid, tri-n-octyl trimellitic acid, octyl oxybenzoate and the like.
(D) Aliphatic dibasic ester plasticizer dibutyl adipate, di-n-hexyl adipate, di (2-ethylhexyl) adipate, di-n-octyl adipate, n-octyl-n-decyl adipate , Diisodecyl adipate, dicapryl adipate, di (2-ethylhexyl) azelate, dimethyl sebacate, diethyl sebacate, dibutyl sebacate, di-n-octyl sebacate, di (2-ethylhexyl) sebacate, di sebacate (2-ethoxyethyl), dioctyl succinate, diisodecyl succinate, dioctyl tetrahydrophthalate, di-n-octyl tetrahydrophthalate and the like.
(E) Fatty acid ester derivatives butyl oleate, glycerin monooleate, methyl acetylricinoleate, pentaerythritol ester, dipentaerythritol hexaester, triacetin, tributyrin and the like.
(F) Oxyacid ester plasticizers Methyl acetyl ricinoleate, butyl acetyl ricinoleate, butyl phthalyl butyl glycolate, tributyl acetyl citrate and the like.
(G) Epoxy plasticizer Epoxidized soybean oil, epoxidized linseed oil, epoxy butyl stearate, decyl epoxy stearate, octyl epoxy stearate, benzyl epoxy stearate, dioctyl epoxy hexahydrophthalate, didecyl epoxy hexahydrophthalate, etc. .
(H) Dihydric alcohol ester plasticizers Diethylene glycol dibenzoate, triethylene glycol di (2-ethylbutyrate) and the like.
(I) Chlorinated plasticizer Chlorinated paraffin, chlorinated diphenyl, chlorinated fatty acid methyl, methoxychlorinated fatty acid methyl, and the like.
(J) Polyester plasticizer Polypropylene adipate, polypropylene sebacate, polyester, acetylated polyester and the like.
(K) Sulfonic acid derivatives p-toluenesulfonamide, o-toluenesulfonamide, p-toluenesulfoneethylamide, o-toluenesulfoneethylamide, toluenesulfone-N-ethylamide, p-toluenesulfone-N-cyclohexylamide and the like.
(L) Citric acid derivatives Triethyl citrate, triethyl acetyl citrate, tributyl citrate, tributyl acetyl citrate, tri (2-ethylhexyl) citrate, n-octyldecyl acetyl citrate and the like.
(M) Others Terphenyl, partially hydrogenated terphenyl, camphor, 2-nitrodiphenyl, dinonylnaphthalene, methyl abietate and the like.

Examples of the lubricant that can be added to each layer include, but are not limited to, the following.
(A) Hydrocarbon compound Liquid paraffin, paraffin wax, microwax, low-polymerized polyethylene and the like.
(B) Fatty acid compounds Lauric acid, myristic acid, palmitic acid, stearic acid, arachidic acid, behenic acid and the like.
(C) Fatty acid amide compounds Stearylamide, palmitylamide, oleylamide, methylenebisstearylamide, ethylenebisstearoamide and the like.
(D) Ester compounds Fatty acid lower alcohol esters, fatty acid polyhydric alcohol esters, fatty acid polyglycol esters, and the like.
(E) Alcohol compounds Cetyl alcohol, stearyl alcohol, ethylene glycol, polyethylene glycol, polyglycerol and the like.
(F) Metal soap Lead stearate, cadmium stearate, barium stearate, calcium stearate, zinc stearate, magnesium stearate and the like.
(G) Natural wax Carnauba wax, candelilla wax, beeswax, whale wax, ibota wax, montan wax and the like.
(H) Other silicone compounds, fluorine compounds and the like.

Examples of the ultraviolet absorber that can be added to each layer include, but are not limited to, the following.
(A) Benzophenone series 2-hydroxybenzophenone, 2,4-dihydroxybenzophenone, 2,2 ', 4-trihydroxybenzophenone, 2,2', 4,4'-tetrahydroxybenzophenone, 2,2'-dihydroxy-4 -Methoxybenzophenone and the like.
(B) Salsylates Phenyl salsylates, 2,4-di-t-butylphenyl-3,5-di-t-butyl-4-hydroxybenzoate, and the like.
(C) Benzotriazole series (2′-hydroxyphenyl) benzotriazole, (2′-hydroxy-5′-methylphenyl) benzotriazole, (2′-hydroxy-5′-methylphenyl) benzotriazole, (2′- Hydroxy-3'-t-butyl-5'-methylphenyl) 5-chlorobenzotriazole and the like.
(D) Cyanoacrylate-based ethyl 2-cyano-3,3-diphenylacrylate, methyl 2-carbomethoxy-3-p-methoxyacrylate, and the like.
(E) Quencher (metal complex)
Nickel (2,2′-thiobis (4-t-octyl) phenolate), nickel dibutyldithiocarbamate, nickel dibutyldithiocarbamate, cobalt dicyclohexyldithiophosphate and the like.
(F) HALS (hindered amine)
Bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate, bis (1,2,2,6,6-pentamethyl-4-piperidyl) sebacate, 1- [2- [3- (3 5-di-t-butyl-4-hydroxyphenyl) propionyloxy] ethyl] -4- [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionyloxy] -2,2,6 6-tetramethylpyridine, 8-benzyl-7,7,9,9-tetramethyl-3-octyl-1,3,8-triazaspiro [4,5] undecane-2,4-dione, 4-benzoyloxy- 2,2,6,6-tetramethylpiperidine and the like.

  The photoconductor manufactured as described above can be reproduced by the reproduction method of the present invention even if it is used repeatedly in the image forming apparatus and reaches the end of its life, but these are only examples, and are reproduced by the method of the present invention. Possible photoconductors are not limited to the photoconductors manufactured as described above, and can be applied to all photoconductors manufactured by a conventionally known method. The life of the photoconductor is determined by the deterioration of the image quality, and the factors that cause the deterioration of the image quality are very large due to impurities and foreign substances existing on the surface and inside of the photoconductor, and the supercritical fluid or subcritical fluid of the present invention. It is because they can be removed on the surface and inside of the photoreceptor by the method of reproducing the photoreceptor using Since organic photoreceptors are greatly affected by impurities due to deterioration of constituent materials over time, the reproduction method of the present invention is particularly effective, but it is possible to obtain a reproduction effect even on inorganic photoreceptors. It is.

  Further, when the organic photoconductor of the laminated structure is subjected to the regenerating process of the present invention, a high cleaning effect is obtained for the layer in which the supercritical fluid or subcritical fluid is formed on the outermost surface of the photoconductor. Depending on conditions and processing time, it may reach the inner layer rather than the outermost surface layer, and a cleaning effect may be obtained over a plurality of layers, which is effective. In addition, if a binder resin having a high glass transition temperature (Tg) is used during the production of the photoreceptor, the margin of temperature and pressure conditions is increased during the regeneration process, and the cleaning effect can be further enhanced. In some cases, improvement in reproduction efficiency can be realized. From such a point, it is more effective in the reproducing method of the present invention to form a crosslinked layer on the outermost surface of the photoreceptor.

Next, the image forming apparatus of the present invention will be described in detail with reference to the drawings.
FIG. 7 is a schematic diagram for explaining the electrophotographic process and the image forming apparatus of the present invention, and the following examples also belong to the category of the present invention. In FIG. 7, a photoconductor (21) is the photoconductor described in FIGS. 1 to 6, and a photoconductor that has been used repeatedly is brought into contact with a supercritical fluid and / or a subcritical fluid and regenerated. is there.

The photoreceptor (21) has a drum shape, but may be a sheet or an endless belt. For charging charger (23), pre-transfer charger (26), transfer charger (29), separation charger (30) and pre-cleaning charger (32), in addition to corotron, scorotron, solid state charger (solid state charger) A roller-shaped charging member or a brush-shaped charging member is used, and all known means can be used.
As the charging member, a non-contact charging method such as corona charging or a contact charging method using a charging member using a roller or a brush is generally used, and any of them can be used effectively in the present invention. In particular, the charging roller can significantly reduce the amount of ozone generated compared to corotron, scorotron, etc., and is effective for stability and prevention of image quality deterioration when the photoreceptor is used repeatedly. However, due to the contact between the photoconductor and the charging roller, the charging roller is contaminated by repeated use, which affects the photoconductor and contributes to the occurrence of abnormal images and reduced wear resistance. It was. In particular, when the photoconductor having high wear resistance according to the present invention is used, it is difficult to perform reface due to surface wear, and thus it is necessary to reduce contamination of the charging roller.

  Therefore, as shown in FIG. 8, the charging charger (23) is disposed close to the photosensitive member (21) through a gap, so that contaminants are less likely to adhere to the charging charger (23) or are easily removed. These effects can be reduced, and the present invention can also be used effectively. In this case, the gap between the photoconductor (21) and the charging charger (23) is preferably small, and is 100 μm or less, more preferably 50 μm or less. However, by making the charging charger (23) non-contact, the discharge becomes non-uniform and the charging of the photosensitive member (21) may become unstable. In the present invention, it is possible to maintain the charging stability by superimposing the AC component on the DC component, thereby simultaneously reducing the influence of ozone, the contamination of the charging charger (23), and the charging effect. Thus, by using in combination with the photoconductor (21) having high wear resistance, further high durability and high image quality are realized.

  Examples of light sources such as an image exposure unit (24) and a static elimination lamp (22) include 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). All of the luminescent materials can be used. Among these, a semiconductor laser (LD) and a light emitting diode (LED) are mainly used. Various types of filters such as a sharp cut filter, a band pass filter, a near infrared cut filter, a dichroic filter, an interference filter, and a color temperature conversion filter can be used to irradiate only light in a desired wavelength range.

In addition to the steps shown in FIG. 7, the light source or the like is provided with a transfer step, a static elimination step, a cleaning step, or a pre-exposure step that uses light irradiation in combination to irradiate the photoreceptor with light. However, the exposure of the photoconductor in the static elimination step has a great influence of fatigue on the photoconductor, and may cause a decrease in charge and an increase in residual potential. Therefore, it may be possible to eliminate static electricity by applying a reverse bias in the charging process or cleaning process, instead of static elimination by exposure, which may be effective from the viewpoint of enhancing the durability of the photoreceptor.
When the electrophotographic photosensitive member is positively (negatively) charged and image exposure is performed, a positive (negative) electrostatic latent image is formed on the surface of the photosensitive member. A positive image can be obtained by developing this with negative (positive) toner (electrodetection fine particles), and a negative image can be obtained by developing with positive (negative) toner. A known method is applied to the developing unit, and a known method is also used for the charge eliminating unit.

As the transfer means, the above-described charger can be generally used, but as shown in FIG. 7, a combination of the transfer charger (29) and the separation charger (30) is effective. Further, the toner image is directly transferred from the photosensitive member to the paper using such a transfer unit. In the present invention, the toner image on the photosensitive member is once transferred to the intermediate transfer member, and then from the intermediate transfer member to the paper. The intermediate transfer method for transferring the toner to the photosensitive member is more preferable for improving the durability or image quality of the photoreceptor.
The intermediate transfer method is particularly effective for image forming apparatuses capable of full-color printing, and controls the prevention of color misregistration by forming a plurality of toner images on the intermediate transfer member and then transferring them to the paper at once. It is easy and effective for high image quality. The intermediate transfer member includes various materials or shapes such as a drum shape and a belt shape. In the present invention, any conventionally known intermediate transfer member can be used and is effective and useful. .

The toner developed on the photosensitive member (21) by the developing unit (25) is transferred to the transfer paper (28), but not all is transferred, and the toner remaining on the photosensitive member (21) is also transferred. Arise. Such toner is removed from the photoreceptor by a fur brush (33) or a blade (34). This cleaning process may be performed only with a cleaning brush or may be performed in combination with a blade, and known cleaning brushes such as a fur brush and a mag fur brush are used.
As described above, the cleaning is a process of removing toner remaining on the photoconductor after transfer. However, the photoconductor is repeatedly rubbed by the above-described blade or brush, so that the photoconductor is worn or damaged. An abnormal image may occur by entering. In addition, if the surface of the photoconductor is contaminated due to poor cleaning, it not only causes an abnormal image, but also significantly reduces the life of the photoconductor. In particular, in the case of a photoreceptor having a layer containing a pigment for improving abrasion resistance on the outermost surface, contaminants attached to the surface of the photoreceptor are difficult to remove. It will promote the occurrence of. Therefore, improving the cleaning property of the photoconductor is very effective for improving the durability and image quality of the photoconductor.

  As means for improving the cleaning property of the photosensitive member, a method of reducing the coefficient of friction on the surface of the photosensitive member is known. Methods for reducing the coefficient of friction on the surface of the photoreceptor are classified into a method in which various lubricants are contained in the photoreceptor surface and a method in which the lubricant is supplied to the photoreceptor surface from the outside. The former is advantageous for small-diameter photoreceptors because of the high degree of freedom in layout around the engine, but the coefficient of friction increases remarkably with repeated use, and there remains a problem in its sustainability. On the other hand, the latter needs to be provided with a component for supplying a lubricating substance, but is effective for enhancing the durability of the photoreceptor because of high stability of the friction coefficient. Among them, the method of adhering to the photoreceptor during development by incorporating a lubricant into the developer is not restricted by the layout around the engine, and the effect of reducing the friction coefficient on the photoreceptor surface is high. Therefore, it is an effective means for improving the durability and image quality of the photoreceptor.

  These lubricants include lubricating fluids such as silicone oil and fluorine oil, various fluorine-containing resins such as PTFE, PFA and PVDF, silicone resins, polyolefin resins, silicone grease, fluorine grease, paraffin wax, fatty acid esters , Fatty acid metal salts such as zinc stearate, lubricating liquids such as graphite and molybdenum disulfide, solids, powders, and the like, but particularly when mixed with a developer, it must be in the form of a powder, especially stearic acid Zinc has little adverse effect and can be used very effectively. When the zinc stearate powder is contained in the toner, it is necessary to consider the balance and influence on the toner, and the content is preferably 0.01 to 0.5% by weight with respect to the toner, preferably 0.1 to 0.3%. 3% by weight is more preferred.

  The photoconductor of the present invention is for a so-called tandem image forming apparatus that includes a plurality of photoconductors corresponding to each developing unit corresponding to a plurality of color toners and performs parallel processing thereby. Even effectively used. The tandem image forming apparatus includes at least four color toners of yellow (C), magenta (M), cyan (C), and black (K) required for full-color printing and a developing unit that holds them. Furthermore, by providing at least four photoconductors corresponding to them, it is possible to perform full-color printing at an extremely high speed as compared with a conventional image forming apparatus capable of full-color printing.

FIG. 9 is a schematic diagram for explaining the tandem-type full-color electrophotographic apparatus of the present invention, and the following modifications also belong to the category of the present invention. In FIG. 9, reference numerals (1C, 1M, 1Y, 1K) are drum-shaped photoconductors, and the photoconductors are the photoconductors of the present invention. The photoreceptors (1C, 1M, 1Y, 1K) rotate in the direction of the arrow in the figure, and at least around them are charged members (2C, 2M, 2Y, 2K) and developing members (4C, 4M, 4Y, 4K). ), Cleaning members (5C, 5M, 5Y, 5K) are arranged. The charging members (2C, 2M, 2Y, 2K) are charging members that constitute a charging device for uniformly charging the surface of the photoreceptor.
Laser light (3C, 3M, 3Y, 3K) from an exposure member (not shown) from the photosensitive member surface side between the charging member (2C, 2M, 2Y, 2K) and the developing member (4C, 4M, 4Y, 4K) , And an electrostatic latent image is formed on the photoreceptor (1C, 1M, 1Y, 1K). Then, four image forming elements (6C, 6M, 6Y, 6K) centering on such a photoreceptor (1C, 1M, 1Y, 1K) are along a transfer conveyance belt (10) which is a transfer material conveyance means. Are juxtaposed. The transfer / conveying belt (10) is provided between the developing member (4C, 4M, 4Y, 4K) and the cleaning member (5C, 5M, 5Y, 5K) of each image forming unit (6C, 6M, 6Y, 6K). 1C, 1M, 1Y, 1K), and a transfer brush (11C, 11M, 11Y, 11K) for applying a transfer bias to the back surface (back surface) of the transfer conveyance belt (10) that contacts the back side of the photoconductor. Is arranged. Each image forming element (6C, 6M, 6Y, 6K) is different in the color of the toner inside the developing device, and the others are the same in configuration.

In the color image forming apparatus having the configuration shown in FIG. 9, the image forming operation is performed as follows. First, in each image forming element (6C, 6M, 6Y, 6K), the charging member (2C, 2M, 2Y) in which the photoconductor (1C, 1M, 1Y, 1K) rotates in the direction of the arrow (direction along with the photoconductor). , 2K), and then an electrostatic latent image corresponding to each color image to be created by laser light (3C, 3M, 3Y, 3K) by an exposure unit (not shown) disposed outside the photoconductor. It is formed.
Next, the latent image is developed by the developing members (4C, 4M, 4Y, 4K) to form a toner image. The developing members (4C, 4M, 4Y, 4K) are developing members that perform development with toners of C (cyan), M (magenta), Y (yellow), and K (black), respectively. 1M, 1Y, and 1K) are overlaid on the transfer paper. The transfer paper (7) is fed out from the tray by the paper feed roller (8), temporarily stopped by the pair of registration rollers (9), and then transferred to the transfer conveyance belt (10) in synchronization with the image formation on the photosensitive member. Sent. The transfer paper (7) held on the transfer / conveying belt (10) is conveyed, and the toner images of the respective colors are transferred at the contact positions (transfer portions) with the respective photoreceptors (1C, 1M, 1Y, 1K). It is.

The toner image on the photosensitive member is transferred onto the transfer paper (by the electric field formed by the potential difference between the transfer bias applied to the transfer brush (11C, 11M, 11Y, 11K) and the photosensitive member (1C, 1M, 1Y, 1K). 7) Transferred on top. Then, the recording paper (7) on which the toner images of four colors are superimposed through the four transfer portions is conveyed to the fixing device (12), where the toner is fixed, and is discharged to a paper discharge portion (not shown). Further, the residual toner remaining on the respective photoconductors (1C, 1M, 1Y, 1K) without being transferred by the transfer unit is collected by the cleaning device (5C, 5M, 5Y, 5K).
In the example of FIG. 9, 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. 9, the charging member is in contact with the photosensitive member, but by using a charging mechanism as shown in FIG. 8, an appropriate gap (about 10 to 200 μm) is provided between them. In addition, the wear amount of the both can be reduced, and toner filming on the charging member can be reduced and the toner can be used satisfactorily.

  The above-described tandem image forming apparatus can transfer a plurality of toner images at a time, so that high-speed full-color printing is realized. However, since at least four photoconductors are required, an increase in the size of the apparatus is unavoidable, and depending on the amount of toner used, there is a difference in the wear amount of each photoconductor, thereby reproducing the color. There are many problems such as a decrease in performance and occurrence of abnormal images. On the other hand, the photoconductor according to the present invention has high wear resistance by forming a protective layer, so that it can be applied even to a small-diameter photoconductor, and the influence of increase in residual potential and sensitivity deterioration is reduced. Even if the usage amounts of the four photoconductors are different, the difference in residual potential and sensitivity over time is small, and it is possible to obtain a full color image with excellent color reproducibility even when used repeatedly for a long time.

The above illustrated electrophotographic process exemplifies an embodiment of the present invention, and of course, other embodiments are possible.
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 includes a charging unit, an exposure 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 example is shown in FIG. The photoconductor (101) is the photoconductor shown in FIGS. 1 to 6, and is a photoconductor regenerated by the reproducing method of the present invention.

  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.

(Synthesis example of a compound having a monofunctional charge transporting structure)
A compound having a monofunctional charge transporting structure is synthesized, for example, by the method described in Japanese Patent No. 3164426. An example of this is shown below.
(1) Synthesis of hydroxy group-substituted triarylamine compound (the following structural formula B) 113.85 g (0.3 mol) of a methoxy group-substituted triarylamine compound (the following structural formula A) and 138 g (0.92 mol) of sodium iodide To this, 240 ml of sulfolane was added and 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 purification was performed by column chromatography (adsorption medium: silica gel, developing solvent: toluene: ethyl acetate = 20: 1). Cyclohexane was added to the obtained pale yellow oil to precipitate crystals. In this way, 88.1 g (yield: 80.4%, melting point: 64.0-66.0 ° C.) of white crystals of the following structural formula B was obtained. Elemental analysis values (%) are shown below.

(2) Triarylamino group-substituted acrylate compound (Exemplary Compound No. 54 in Table 1)
82.9 g (0.227 mol) of the hydroxy group-substituted triarylamine compound (Structural Formula B) obtained in (1) above was dissolved in 400 ml of tetrahydrofuran, and an aqueous sodium hydroxide solution (NaOH: 12.4 g, Water: 100 ml) was added dropwise. 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 purification was performed by column chromatography (adsorption medium: silica gel, developing solvent: toluene). N-Hexane was added to the obtained colorless oil to precipitate crystals. In this way, Exemplified Compound No. As a result, 80.73 g of 54 white crystals (yield = 84.8%, melting point: 117.5 to 119.0 ° C.) was obtained. Elemental analysis values (%) are shown below.

(Photoreceptor Production Example 1)
An undercoat layer coating solution having the following composition was applied onto an aluminum tube having an outer diameter of 30 mm, followed by drying at 130 ° C. for 20 minutes to form an undercoat 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. for 20 minutes to form a charge generation layer of about 0.2 μm. Further, after coating using a coating solution for charge transport layer having the following composition, drying was performed at 130 ° C. for 20 minutes to form a charge transport layer of about 28 μm, and Photoconductor 1 was produced. In all cases, the dip coating method was used.
(Coating liquid for undercoat layer)
Titanium oxide CR-EL (Ishihara Sangyo Co., Ltd.): 50 parts Alkyd resin Beckolite M6401-50
(Solid content 50% by weight, manufactured by Dainippon Ink & Chemicals, Inc.): 15 parts melamine resin L-145-60
(Solid content 60% by weight, manufactured by Dainippon Ink & Chemicals, Inc.): 8 parts 2-butanone: 120 parts (coating liquid for charge generation layer)
Asymmetric bisazo pigment having the following structural formula: 2.5 parts

ポリビニルブチラール（「ＸＹＨＬ」ＵＣＣ製）：０．５部
２−ブタノン：１１０部
シクロヘキサノン：２６０部
（電荷輸送層用塗工液）
ビスフェノールＺポリカーボネート
（「パンライトＴＳ−２０５０」帝人化成製）：１０部
下記構造式で示される電荷輸送物質：７部

Polyvinyl butyral ("XYHL" manufactured by UCC): 0.5 part 2-butanone: 110 parts cyclohexanone: 260 parts (coating liquid for charge transport layer)
Bisphenol Z polycarbonate ("Panlite TS-2050" manufactured by Teijin Chemicals): 10 parts Charge transport material represented by the following structural formula: 7 parts

テトラヒドロフラン：８０部
下記構造式で示される硫黄系酸化防止剤：０．５部

Tetrahydrofuran: 80 parts Sulfur-based antioxidant represented by the following structural formula: 0.5 parts

シリコーンオイル（１００ｃｓ、信越化学工業社製）：０．００２部

Silicone oil (100 cs, manufactured by Shin-Etsu Chemical Co., Ltd.): 0.002 parts

(Photoreceptor Production Example 2)
The film thickness of the charge transport layer of the photoreceptor 1 obtained in the photoreceptor production example 1 was changed to 23 μm, and further coated on the surface with a protective layer coating solution having the following composition, followed by drying at 130 ° C. for 20 minutes. Then, a protective layer having a thickness of about 5 μm was formed to produce a photoreceptor 2. The spray coating method was used for coating.
(Coating liquid for protective layer)
Polytetrafluoroethylene resin fine particles ("Lublon L-2" manufactured by Daikin Industries): 1 part Dispersing aid (non-volatile content 25%, "Aron GF300" manufactured by Toagosei Co., Ltd.): 0.2 parts Bisphenol Z polycarbonate (" Panlite TS-2050 (manufactured by Teijin Chemicals): 10 parts Charge transport material represented by the following structural formula: 8 parts

テトラヒドロフラン：１７０部

Tetrahydrofuran: 170 parts

(Photoreceptor Production Example 3)
The thickness of the charge transport layer of the photoconductor 1 obtained in Photoconductor Production Example 1 was changed to 23 μm, and further coated on the surface with a protective layer coating solution having the following composition, followed by drying at 130 ° C. for 20 minutes. Then, a protective layer having a thickness of about 5 μm was formed to produce a photoreceptor 3. The spray coating method was used for coating.
(Coating liquid for protective layer)
Alumina (average primary particle size: 0.3 μm, “AA-03” manufactured by Sumitomo Chemical Co., Ltd.): 4 parts Dispersion aid (non-volatile content: 50%, “BYK-P104” manufactured by BYK Chemie): 0.04 parts Bisphenol Z polycarbonate ("Panlite TS-2050" manufactured by Teijin Chemicals): 10 parts Charge transport material represented by the following structural formula: 7 parts

テトラヒドロフラン：５３０部
シクロヘキサノン：１４５部

Tetrahydrofuran: 530 parts Cyclohexanone: 145 parts

(Photoreceptor Production Example 4)
The film thickness of the charge transport layer of the photoreceptor 1 obtained in the photoreceptor production example 1 was changed to 23 μm, and further coated on the surface with a protective layer coating solution having the following composition, followed by drying at 130 ° C. for 20 minutes. Then, a protective layer having a thickness of about 5 μm was formed to produce a photoreceptor 4. The spray coating method was used for coating. After spray coating, it was naturally dried for 20 minutes, and then light-irradiated under conditions of a metal halide lamp: 160 W / cm, irradiation intensity: 500 mW / cm ² , and irradiation time: 60 seconds to cure the coating film. Thereafter, the photosensitive member 4 was produced by heating and drying at 130 ° C.
(Coating liquid for protective layer)
Trifunctional or higher functional radical polymerizable monomer having no charge transport structure: 10 parts (Trimethylolpropane triacrylate (KAYARAD TMPTA, Nippon Kayaku)
Molecular weight: 296, number of functional groups: trifunctional, molecular weight / number of functional groups = 99)
Radical polymerizable compound having a monofunctional charge transporting structure: 10 parts (Exemplary Compound No. 54)
Photopolymerization initiator: 1 part (1-hydroxy-cyclohexyl-phenyl-ketone (Irgacure 184, manufactured by Ciba Specialty Chemicals))
Tetrahydrofuran: 100 parts

(Accelerated fatigue test 1)
The photoreceptors 1 to 4 obtained as described above are mounted in an electrophotographic process cartridge, and the initial stage is set using a Ricoh digital copier remodeling machine using a 655 nm semiconductor laser as a charging roller and an image exposure light source. The voltage applied to the charging roller was adjusted so that the dark part potential (VD) of the film became 800 (−V), and the exposed part potential (VL) was measured and the image was evaluated. The initial evaluation was performed in a normal temperature and normal humidity environment (25 ° C. and 55% RH). Thereafter, 50,000 sheets were printed repeatedly, and dark part potential (VD) and exposure part potential (VL) were measured and image evaluation was performed. Evaluation after printing 50,000 sheets was performed in a high temperature and high humidity environment (30 ° C., 80% RH). Further, the amount of wear was evaluated from the difference in film thickness at the initial stage and after printing 50,000 sheets. These results are shown in Table 4.

(Examples 1-4)
The photoconductors 1 to 4 subjected to accelerated fatigue were placed in a pressure resistant reaction cell shown in FIG. 11, and all valves were closed. Next, the valve 1 (V1) and the valve 3 (V3) are opened, and the pressure is controlled by the back pressure valve, while carbon dioxide is supplied from the supply cylinder to the pressure resistant reaction cell, and the temperature regulator using the pressurizing pump 1 and the temperature control jacket. Then, while stirring the pressure-resistant reaction cell, the temperature and pressure were adjusted to 80 ° C. and 30 MPa over about 30 minutes. After the temperature and pressure were stabilized, the temperature and pressure were maintained for 2 hours. Then, while controlling the temperature and pressure inside the pressure-resistant reaction cell with the temperature control jacket and back pressure valve, the temperature is gradually lowered and reduced over about 30 minutes until the temperature reaches 25 ° C. and atmospheric pressure, and the regenerated photoconductor is removed. Obtained. Further, impurities extracted by the processing, deposits that deteriorate the characteristics of the photoreceptor, and the like were collected by a collection mechanism (not shown). The recovery mechanism was separated from the back pressure valve, and the extract was brought to room temperature and normal pressure and collected as a solid. In the figure, symbols (V1) to (V3) represent valves 1 to 3, (T) represents a temperature sensor, and (P) represents a pressure sensor.

(Example 5)
The photoreceptor 3 subjected to accelerated fatigue as described above is placed in a pressure vessel cell, and further 3 parts of a charge transport material represented by the following structural formula and 0.1 part of a sulfur-based antioxidant represented by the following structural formula are added. Carbon dioxide was selected as the critical fluid, and a regeneration process was performed under the same conditions as in Example 3 to obtain a regenerated photoreceptor.

(Comparative Examples 1-4)
The photoreceptors 1 to 4 subjected to accelerated fatigue as described above were not subjected to any regeneration processing and left in a dark place for 3 hours to obtain an untreated photoreceptor.
(Comparative Example 5)
The surface of the photoconductor 4 subjected to accelerated fatigue as described above was wiped off with ion-exchanged water, and then wiped off with ethanol and finally wiped dry to wash the photoconductor to obtain a wiped photoconductor.

(Accelerated fatigue test 2)
Ricoh digital cameras using the reprocessed photoreceptors 1-5 and unprocessed photoreceptors 1-5 obtained as described above in an electrophotographic process cartridge and using a 655 nm semiconductor laser as the charging roller and image exposure light source. Using a modified copier, the voltage applied to the charging roller was adjusted so that the initial dark portion potential (VD) was 800 (−V), and the exposure portion potential (VL) was measured and the image was evaluated. The initial evaluation was performed in a normal temperature and normal humidity environment (25 ° C. and 55% RH). Thereafter, printing on 10,000 sheets was repeated, and dark part potential (VD) and exposure part potential (VL) were measured and image evaluation was performed. Evaluation after printing 10,000 sheets was performed in a high temperature and high humidity environment (30 ° C., 80% RH). In addition, the abrasion amount (μm) was evaluated from the difference in film thickness at the initial stage and after printing 10,000 sheets. These results are shown in Table 5.

  By performing the accelerated fatigue test 1, it was confirmed that the charge transport layer of the photoconductor 1 was greatly reduced, resulting in the occurrence of background contamination and a decrease in gradation. In Photoreceptor 2, the amount of decrease in film thickness was reduced as compared with Photoreceptor 1, and the background smudge was somewhat improved, but the increase in VL was large and a decrease in image density was observed. Photoreceptor 3 was improved in abrasion resistance by the formation of a protective layer, and no scumming was observed, but foreign matter adhesion and poor cleaning were observed, and the resolution of images in a high-temperature and high-humidity environment decreased. . The abrasion resistance of the photoreceptor 4 was also greatly improved and no scumming was observed, but foreign matter adhesion was observed, resulting in a decrease in resolution.

  The photoreceptors 1 to 5 subjected to the reproduction processing of the present invention were improved to the state before the accelerated fatigue test was performed. Further, when 10,000 sheets were printed, the photoconductors 1 and 2 had a small reduction in film thickness due to accelerated fatigue test 1, so the background stain was slightly improved, but still improved by improving the charging property. Other characteristics were also improved uniformly. On the other hand, the photoreceptor on which the protective layer was formed was greatly improved by the reproduction process, and high image quality was realized. A photoreceptor in which wear is suppressed by forming a protective layer can sufficiently obtain the reproducing effect of the present invention even if the characteristics deteriorate due to repeated use. On the other hand, the photoconductors that have not been subjected to the reproduction process do not change in characteristics even when left for the time spent for the reproduction process. There wasn't. Further, when the photosensitive member 4 subjected to the accelerated fatigue test 1 is not subjected to the regeneration treatment of the present invention but only the surface of the photosensitive member using ionic exchange water or ethanol, the foreign matter adhering to the surface of the photosensitive member is somewhat reduced. Although it was removed and the resolution was improved, it was revealed that when the accelerated fatigue test was repeated again, the image quality deteriorated immediately and was not reproduced.

  As can be seen from the above results, the chargeability and residual potential are improved by regenerating the photoconductor whose image quality has deteriorated by repeated use with a supercritical fluid and / or subcritical fluid, and cleaning. As a result, it becomes possible to remove the deposits on the surface of the photoreceptor, which cause deterioration of the performance, to realize high image quality, and to reproduce the photoreceptor almost as it was at the time of manufacture. In particular, a photoconductor having a protective layer formed in advance to improve the wear resistance has a very high effect by the regeneration treatment of the present invention because the amount of wear is small even after repeated use. It was found to be more effective. On the other hand, if the reproduction processing of the present invention is not performed, the image quality is significantly deteriorated, and even when the surface of the photosensitive member is wiped off, the resolution is temporarily improved, but it cannot withstand repeated use and is not reproduced. I knew it was n’t there. Therefore, the reproduction processing of the photosensitive member brought into contact with the supercritical fluid and / or subcritical fluid of the present invention is excellent in any of the image quality improvement effect, processing efficiency, and workability, and the manufacturing, disposal, and processing of the photosensitive member. Thus, an extremely effective photoconductor reproduction method that has not been conventionally available and which can realize a significant reduction in environmental load and cost associated with the present invention has been provided.

It is a figure which shows an example of the photoreceptor of this invention. It is a figure which shows the other example of the photoreceptor of this invention. It is a figure which shows the other example of the photoreceptor of this invention. It is a figure which shows the other example of the photoreceptor of this invention. It is a figure which shows the other example of the photoreceptor of this invention. It is a figure which shows the other example of the photoreceptor of this invention. It is a figure which shows an example of the image forming apparatus of this invention. It is a figure which shows an example of arrangement | positioning of a photoconductor and a charging roller. It is a figure which shows the other example of the image forming apparatus of this invention. It is a figure which shows an example of the process cartridge of this invention. It is the schematic of a supercritical processing apparatus.

Explanation of symbols

(About Figure 7)
21 Photoconductor 22 Static elimination lamp 23 Charger charger 24 Image exposure unit 25 Development unit 26 Pre-transfer charger 27 Registration roller 28 Transfer paper 29 Transfer charger 30 Separation charger 31 Separation claw 32 Pre-cleaning charger 33 Fur brush 34 Blade (FIG. 9)
1C, 1M, 1Y, 1K Photoconductor 2C, 2M, 2Y, 2K Charging member 3C, 3M, 3Y, 3K Laser beam 4C, 4M, 4Y, 4K Developing member 5C, 5M, 5Y, 5K Cleaning member 6C, 6M, 6Y , 6K image forming element 7 transfer paper 8 paper feed roller 9 registration roller 10 transfer transport belt 11C, 11M, 11Y, 11K transfer brush 12 fixing device (about FIG. 10)
DESCRIPTION OF SYMBOLS 101 Drum 102 Contact charging apparatus 103 Image exposure 104 Developing apparatus 105 Transfer body 106 Contact transfer apparatus 107 Cleaning unit (about FIG. 11)
V1 Valve 1
V2 Valve 2
V3 Valve 3
T Temperature sensor P Pressure sensor

Claims (12)

A charging step for charging at least the surface of the electrophotographic photosensitive member, an electrostatic latent image forming step for forming an electrostatic latent image on the electrophotographic photosensitive member, and a visible image formed by attaching toner to the electrostatic latent image A supercritical fluid and / or a subcritical fluid is brought into contact with the surface of an electrophotographic photosensitive member repeatedly used in an image forming process including a developing step and a transfer step of transferring the visible image to a recording medium. A method for regenerating an electrophotographic photosensitive member. The method for regenerating an electrophotographic photosensitive member according to claim 1, wherein a protective layer is formed on the surface of the electrophotographic photosensitive member. The method for regenerating an electrophotographic photosensitive member according to claim 2, wherein the protective layer contains a binder resin that has been subjected to a crosslinking treatment. 4. The method for regenerating an electrophotographic photosensitive member according to claim 1, wherein the supercritical fluid and / or subcritical fluid is carbon dioxide. 5. The method for regenerating an electrophotographic photosensitive member according to claim 4, wherein the supercritical fluid and / or subcritical fluid is a mixture with carbon dioxide. 6. The electrophotographic photosensitive member according to claim 5, wherein the mixture is a mixture of carbon dioxide and at least one selected from carbon monoxide, nitrogen, water, ammonia, methanol, ethanol, ethane, and propane. How to regenerate the body. The method for regenerating an electrophotographic photosensitive member according to claim 1, wherein the supercritical fluid and / or the subcritical fluid is circulated in the contact step. The substance other than the binder resin contained in the outermost surface layer of the electrophotographic photosensitive member is previously contained in a supercritical fluid and / or a subcritical fluid, according to any one of claims 1 to 7. A method for regenerating an electrophotographic photoreceptor. An electrophotographic photosensitive member regenerated by the reproducing method according to claim 1. A charging step for charging at least the surface of the electrophotographic photosensitive member, an electrostatic latent image forming step for forming an electrostatic latent image on the electrophotographic photosensitive member, and a visible image formed by attaching toner to the electrostatic latent image An image forming method comprising a developing step and a transfer step of transferring the visible image to a recording medium, wherein the electrophotographic photosensitive member is the electrophotographic photosensitive member according to claim 9. Forming method. A charging means for charging at least the surface of the electrophotographic photosensitive member, an electrostatic latent image forming means for forming an electrostatic latent image on the electrophotographic photosensitive member, and a visible image formed by attaching toner to the electrostatic latent image An image forming apparatus comprising: a developing unit that performs transfer; and a transfer unit that transfers the visible image to a recording medium, wherein the electrophotographic photosensitive member is the electrophotographic photosensitive member according to claim 9. Forming equipment. A charging means for charging the surface of the electrophotographic photosensitive member, an electrostatic latent image forming means for forming an electrostatic latent image on the electrophotographic photosensitive member, and a toner is attached to the electrostatic latent image to form a visible image. 10. At least one means selected from developing means, transfer means for transferring the visible image to a recording medium, and cleaning means for removing toner remaining on the surface of the electrophotographic photosensitive member after transfer, and the transfer means according to claim 9. A process cartridge for an image forming apparatus, which is integrated with an electrophotographic photosensitive member and is detachable from an image forming apparatus main body.

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