JP4837493B2 - Method for manufacturing electrophotographic photosensitive member, and electrophotographic photosensitive member and image forming apparatus obtained by the manufacturing method - Google Patents

Description

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

  As an electrophotographic photosensitive member used in an image forming apparatus, an organic photosensitive material using an organic photosensitive material is generally widely applied for reasons such as cost, productivity, and environmental stability. The layer structure of these electrophotographic photoreceptors is a single layer type having a charge generation function and a charge transport function in one layer, and functions as a charge generation layer having a charge generation function and a charge transport layer having a charge transport function. It is roughly divided into separate laminated type photoreceptors, and the latter is widely used from the viewpoint of stability of electrostatic characteristics and durability.

  The mechanism of electrostatic latent image formation in a function-separated type photoconductor is that when the photoconductor is charged and then irradiated with light, the light passes through the charge transport layer and is absorbed by the charge generation material in the charge generation layer to generate a charge. To do. The charges generated thereby are injected into the charge transport layer at the interface between the charge generation layer and the charge transport layer, and further moved through the charge transport layer by an electric field, reach the surface of the photoreceptor, and the surface charge given by the charge becomes medium. An electrostatic latent image is formed by summing. Therefore, it is preferable in terms of electrophotographic characteristics that the charges generated by light are smoothly trapped on the surface of the photoreceptor without being trapped during the movement.

  However, organic photoreceptors have many factors that trap charges, and the purity of the photosensitive material and the binder resin that binds them is one factor. If there are many impurities in the photosensitive layer, they are easily trapped in the charge transfer process, thereby causing a decrease in sensitivity, an increase in residual potential, and the like, thereby promoting the generation of abnormal images. Therefore, these materials used for the photoreceptor need to maintain a very high purity. These impurities that affect sensitivity reduction and residual potential increase include raw materials, intermediates, and external contaminants remaining in the manufacturing process of photosensitive materials and binder resins, as well as reaction generation due to decomposition and alteration during storage. Things are also included. In particular, the photosensitive material is likely to deteriorate over time and has a great influence on the deterioration of electrophotographic characteristics because it plays the role of charge generation and charge transport.

  Therefore, in order to maintain good electrophotographic characteristics of the photoreceptor and to enable stable output of high-quality images, it is necessary to increase the purity of the photosensitive material and binder resin used in the photoreceptor, and this is why It was necessary to carry out a purification treatment. However, in the conventional method for refining the photosensitive material and the binder resin, it is necessary to carry out the refining process many times in order to increase the purity, and the refining process includes steps such as washing, filtration, and drying. A lot of time and various facilities are required. Furthermore, it is necessary to select an organic solvent suitable for the material to be purified, and the efficiency of the purification process is very low. For this reason, a large amount of organic solvent is required over a long period of time to purify the material, and waste liquid is increased.

  In recent years, supercritical fluids have attracted attention as methods for cleaning, extraction, separation, and the like. 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 a charge generating substance are disclosed (see Patent Documents 1 to 4). It is also disclosed as a method for cleaning a conductive support (Patent Document 5). It is also disclosed as a method for purifying resin fine particles contained in the surface layer (Patent Documents 6 and 7).

  In this way, by processing these photosensitive materials contained in the photoreceptor with a supercritical fluid, the electrophotographic characteristics are improved and the purification can be performed more efficiently. This is a very effective method in the field of photoreceptors. However, these methods are obtained by processing a photosensitive material using a supercritical fluid, and although the efficiency is improved as compared with the conventional method, a dramatic effect cannot be expected.

  This is because, even if the high purity of the photosensitive material can be achieved, a process of applying them using an organic solvent and drying them is necessary in the production process of the photoreceptor. That is, the organic solvent remains on the photoconductor coated with a coating solution containing an organic solvent, which causes an increase in the residual potential, and the stability of the electrophotographic characteristics over time when the photoconductor is stored. It will be reduced. If the drying is performed at a higher temperature after coating in order to reduce the amount of the residual organic solvent, the amount of the residual organic solvent can be reduced, but the photosensitive material is adversely affected and the effect is not obtained.

The photosensitive material used for the photosensitive member and the binder resin that binds them, all of the materials contained in the photosensitive member are trapped unless they have high purity, and the electrophotographic characteristics of the photosensitive member are degraded. cause. This not only reduces the life of the photoconductor, but also significantly deteriorates the output image, thereby reducing the life of the image forming apparatus and the process cartridge used therefor. Further, even if the material used for the photoreceptor can be highly purified, the influence of the organic solvent remaining after the photosensitive layer is applied cannot be avoided. When a high temperature drying process is performed to remove the organic solvent, the photosensitive material is adversely affected, and thus the problem cannot be solved. In order to maintain excellent electrophotographic characteristics stably even after repeated use of the photoreceptor, it is necessary to remarkably reduce impurities and residual solvent. However, in the conventional production method, a photosensitive layer is applied to expose the photosensitive material. It is impossible to wash or remove impurities and solvents at the final stage of production of the body, and there has been a strong demand for a new method of producing a photoreceptor that enables this.
Japanese Patent Laid-Open No. 07-134435 JP 2001-092165 A JP 2002-138216 A JP 2002-356627 A JP 2001-121094 A Japanese Patent Laid-Open No. 07-134435 Japanese Patent No. 3186010

  The present invention provides a novel photoconductor manufacturing method that realizes processing after applying a photosensitive layer and the like, which could not be realized by the conventional photoconductor manufacturing method, in view of the problems of the above-described conventional technology, and thereby An object of the present invention is to provide an electrophotographic photosensitive member, an image forming apparatus, and a process cartridge capable of maintaining stable electrophotographic characteristics even after repeated use and capable of stably outputting a high-quality image.

  The present invention relates to a method for refining a photoconductor constituting material that greatly affects the electrophotographic characteristics of an electrophotographic photoconductor, wherein a photosensitive layer or the like is applied on a conductive support and the photosensitive layer or the like is formed. In particular, this is a method for producing a photoconductor in which a photosensitive layer or the like is contacted with a supercritical fluid and / or a subcritical fluid after forming a photosensitive layer or the like. As a result, not only can the impurities contained in the photosensitive layer etc. be removed at the final stage of the formation of each layer such as the photosensitive layer of the photoreceptor, but also the organic solvent remaining in the coating process of the photosensitive layer etc. can be removed. This is very effective for reducing the electrophotographic characteristics, particularly the reduction in sensitivity and the increase in residual potential. The photoconductor of the present invention obtained by these production methods removes impurities and residual solvent contained therein, reduces sensitivity reduction and residual potential increase, reduces electrophotographic characteristics over time, and provides long-term high-quality images. Stabilization is possible.

That is, the present invention has been completed by the following constituent requirements.
(1) In a method for producing an electrophotographic photosensitive member having a single-layer photosensitive layer mainly composed of at least a charge generating material, a charge transporting material and a binder resin on a conductive support, A method for producing an electrophotographic photoreceptor, comprising forming the photosensitive layer and then contacting the photosensitive layer with supercritical carbon dioxide and / or subcritical carbon dioxide .
(2) In a method for producing an electrophotographic photosensitive member having 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 on a conductive support. Forming the charge generation layer on the conductive support, and / or forming the charge transport layer on the charge generation layer, and then converting the charge transport layer to supercritical carbon dioxide and / or sublimation. A method for producing an electrophotographic photosensitive member, which comprises contacting with critical carbon dioxide .
(3) In a method for producing an electrophotographic photosensitive member in which an undercoat layer is formed on a conductive support and a single-layer photosensitive layer or a charge generation layer and a charge transport layer are further formed, on the conductive support. Further, after forming the undercoat layer, at least the undercoat layer is brought into contact with supercritical carbon dioxide and / or subcritical carbon dioxide .
(4) In the method for producing an electrophotographic photosensitive member having a protective layer formed on the outermost surface of the electrophotographic photosensitive member, at least after forming the protective layer, the protective layer is changed to a supercritical fluid and / or a subcritical fluid. A method for producing an electrophotographic photosensitive member, which is brought into contact.

( 5 ) The method for producing an electrophotographic photosensitive member according to any one of (1) to ( 4 ), wherein the supercritical carbon dioxide and / or subcritical carbon dioxide is circulated.
(6) and characterized in that it is contained the supercritical carbon dioxide and / or nitrous advance supercritical carbon dioxide and / or subcritical carbon dioxide material other than the binder resin contained in the layer is brought into contact with supercritical carbon dioxide The method for producing an electrophotographic photosensitive member according to any one of (1) to ( 5 ).

  According to the present invention, the inside of the photosensitive layer, the undercoat layer, and the protective layer after applying the photosensitive layer, the undercoat layer, and the protective layer, which could not be realized by the conventional manufacturing method, is supercritical fluid and / or subcritical fluid. In addition to removing impurities, etc. contained in the photosensitive layer, undercoat layer and protective layer, it is possible to remove the organic solvent remaining in the photosensitive layer, undercoat layer and protective layer. A novel photoreceptor manufacturing method is provided. In particular, supercritical fluids and / or subcritical fluids that are gases under normal temperature and normal pressure, such as carbon dioxide, have both solubility and permeability, so that they can be processed to the inside of photosensitive layers and the like. This is a particularly effective method for the post-processing of the photoconductor because it is gas and can be dried under normal temperature and pressure because of its excellent drying property.

  By removing the impurities by the method for producing a photoreceptor of the present invention, sensitivity reduction and residual potential increase are greatly reduced, and residual solvent contained in the photosensitive layer, undercoat layer, and protective layer is almost removed. Therefore, it is possible to provide a photoconductor that can reduce fluctuations in electrophotographic characteristics during storage and can maintain stable electrophotographic characteristics even after repeated use over a long period of time. Further, by using these photoconductors, an image forming apparatus and a process cartridge capable of repeatedly outputting high-quality images for a long period of time are provided.

Next, the best mode for carrying out the present invention will be described.
First, the supercritical fluid and 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 low critical temperature is preferable. 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.

  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. That is, even when a subcritical fluid such as subcritical carbon dioxide is brought into contact with the photoconductor, it is possible to obtain processing effects such as a photosensitive layer and an undercoat layer. Supercritical fluids may be too soluble and it may be preferable to use subcritical fluids instead of supercritical fluids for purposes of the process of the present invention. 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 sub-fluid such as carbon monoxide, nitrogen, water, ammonia, ethane, propane, ethylene, etc. A critical fluid can be used in combination. Moreover, an organic solvent (entrainer) can also be mixed with the supercritical fluid and the subcritical fluid. 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 treatment effect. . However, since the main use purpose of the supercritical fluid and / or subcritical fluid in the present invention is cleaning of the photosensitive layer and the undercoat layer, the condition for completely dissolving the binder resin is not preferable. In the case of an inorganic photoconductor, the effect may be exerted by using a supercritical fluid together or by mixing an entrainer. However, in the case of an organic photoconductor, unless the cleaning effect needs to be greatly enhanced. Even with carbon dioxide alone, a sufficient effect can be obtained.

  An apparatus using a supercritical fluid and / or a subcritical fluid may include a supercritical fluid and / or a subcritical fluid after an undercoat layer, a single-layer photosensitive layer, a charge generation layer, a charge transport layer, or a protective layer is formed. Any device can be used as long as it can contact the fluid. Batch method using supercritical fluid and / or subcritical fluid in closed system, distribution method using circulating supercritical fluid and / or subcritical fluid, combined method combining batch method and distribution method, 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 used. Thereby, the extracted impurities can be taken out of the system.

  Also, when processing a photoconductor using a supercritical fluid and / or subcritical fluid, components other than the binder resin contained in the layer to be processed may be extracted depending on the temperature and pressure conditions. There is. Although it is possible to adjust them so that they are not extracted under temperature and pressure conditions, other methods include incorporating components other than the binder resin of the layer to be processed into a supercritical fluid and / or a subcritical fluid in advance. Thus, it is possible and effective to keep the components in an equilibrium state inside and outside the layer to be treated during the treatment with the supercritical fluid and / or the subcritical fluid, and to extract only the impurities.

The photoreceptor of the present invention will be described with reference to the drawings.
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. After the photosensitive layer is applied and dried, the supercritical fluid and In contact with the subcritical fluid, the treatment is performed.
FIG. 2 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. Either or both of the generation layer and the charge transport layer are applied and dried, and then contacted with a supercritical fluid and / or a subcritical fluid to be processed.

FIG. 3 shows a photoconductor 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. Alternatively, after both are applied and dried, they are brought into contact with a supercritical fluid and / or a subcritical fluid to be treated.
FIG. 4 shows a photoreceptor in which an undercoat layer, a charge generation material 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. Any one or all of the undercoat layer, the charge generation layer, and the charge transport layer are applied and dried, and then contacted with a supercritical fluid and / or a subcritical fluid and subjected to treatment.

  In the present invention, the treatment with the supercritical fluid and / or the subcritical fluid may be performed on all layers formed on the conductive support, or selectively performed on one or two of them. When the treatment is performed by bringing the layer formed on the conductive support into contact with the supercritical fluid and / or the subcritical fluid, the number is not limited to the number of treatments, and all the layers are included.

Examples of the conductive support include those having a volume resistance of 10 ¹⁰ Ω · cm or less, such as metals such as aluminum, nickel, chromium, nichrome, copper, gold, silver, and platinum, tin oxide, and indium oxide. Metal oxide coated with film or cylindrical plastic or paper by vapor deposition or sputtering; 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. Further, endless nickel belts and endless stainless steel belts disclosed in JP-A-52-36016 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.

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.
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.

  By forming at least a charge generation layer on a conductive support, contacting the charge generation layer with a supercritical fluid and / or subcritical fluid, and performing treatment with the supercritical fluid and / or subcritical fluid, Impurities contained in the charge generation material and binder resin contained in the charge generation layer are removed. Further, the coating solvent remaining in the layer when the charge generation layer is applied can be removed.

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.

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 liquid for the charge transport layer is mainly composed of a charge transport material, a binder resin and a solvent, but may contain additives such as a single plasticizer, a leveling agent, an antioxidant or a lubricant as needed. It may be added.

  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.

  After forming at least the charge transport layer on the conductive support, the charge transport layer is brought into contact with the supercritical fluid and / or subcritical fluid, and treatment with the supercritical fluid and / or subcritical fluid is performed, Impurities contained in the charge transport material and binder resin contained in the charge transport layer can be removed. Further, the coating solvent remaining in the layer when the charge transport layer is applied can be removed.

  Next, the case where the photosensitive layer has a single layer structure will be described. This is a photoreceptor in which the charge generation material and the charge transport material described above are dispersed and / or dissolved in a binder resin to realize the charge generation function and the 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. 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.

  After forming at least a single-layer photosensitive layer on a conductive support, the single-layer photosensitive layer is brought into contact with a supercritical fluid and / or a subcritical fluid, and processed with a supercritical fluid and / or a subcritical fluid. Thus, the charge transport material contained in the single layer photosensitive layer and the impurities contained in the binder resin can be removed. Further, the coating solvent remaining in the layer when the single photosensitive layer is applied can be removed.

  In the photoreceptor of the present invention, 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 copolymer nylon and methoxymethylated nylon, polyurethane, melamine resins, phenol resins, alkyd-melamine resins, and isocyanates. And curable resins that form a three-dimensional network structure, such as epoxy resins. 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.

  By forming at least an undercoat layer on the conductive support, contacting the undercoat layer with a supercritical fluid and / or a subcritical fluid, and performing a treatment with the supercritical fluid and / or the subcritical fluid, Impurities contained in fine powder pigments such as binder resin and metal oxide contained in the undercoat layer can be removed. Further, the coating solvent remaining in the layer when the undercoat layer is applied can be removed.

  Furthermore, in the photoreceptor of the present invention, an intermediate layer can be provided 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.

Furthermore, in the present invention, a protective layer can be provided on the outermost surface of the photoreceptor. The protective layer is formed mainly for the purpose of enhancing the wear resistance of the photosensitive member or preventing the adhesion of foreign matter, thereby realizing a long life and high stability of the photosensitive member. For the protective layer formed on the outermost surface of the photoreceptor, a method of using a polymer charge transport material for the binder resin or dispersing fine particles is known and useful.
The above-described polymer charge transporting material is a material having both the function of a binder resin and the function of a charge transporting material, and is effective in improving wear resistance. 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、Ｒ₁、Ｒ₂、Ｒ₃はそれぞれ独立して置換もしくは無置換のアルキル基又はハロゲン原子、Ｒ₄は水素原子又は置換もしくは無置換のアルキル基、Ｒ₅、Ｒ₆は置換もしくは無置換のアリール基、ｏ、ｐ、ｑはそれぞれ独立して０〜４の整数、ｋ、ｊは組成を表し、０．１≦ｋ≦１、０≦ｊ≦０．９、ｎは繰り返し単位数を表し５〜５０００の整数である。Ｘは脂肪族の２価基、環状脂肪族の２価基、または下記一般式で表される２価基を表す。尚、（Ｉ）式は２つの共重合種が交互共重合体の形で記載されているが、ランダム共重合体でも構わない。 These are illustrated below and specific examples are shown.

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 and q are each independently an integer of 0 to 4, k and j are compositions, 0.1 ≦ k ≦ 1, 0 ≦ j ≦ 0.9, and 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.

Ｒ₁₀₁、Ｒ₁₀₂は各々独立して置換もしくは無置換のアルキル基、アリール基またはハロゲン原子を表す。ｌ、ｍは０〜４の整数、Ｙは単結合、炭素原子数１〜１２の直鎖状、分岐状もしくは環状のアルキレン基、−Ｏ−、−Ｓ−、−ＳＯ−、−ＳＯ₂−、−ＣＯ−、−ＣＯ−Ｏ−Ｚ−Ｏ−ＣＯ−（式中Ｚは脂肪族の２価基を表す。）または、

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

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

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

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

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

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

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

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 formula (I). In the formula (V), two copolymer species are described in the form of an alternating copolymer, but a random copolymer may be used.

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

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 formula (I). In the formula (VI), two copolymer species are described in the form of an alternating copolymer, but a random copolymer may be used.

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

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

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

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

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.

  Next, the fine particle dispersion type protective layer will be described. By dispersing the fine particles, it is possible to increase the life of the photoreceptor by increasing the film strength and / or the surface lubricity. Examples of the fine particles contained in the protective layer include organic fillers and inorganic fillers. Examples of the organic filler material include fluororesin fine particles such as polytetrafluoroethylene, silicone resin powder, and a-carbon powder. Examples of the inorganic filler material include metal powders such as copper, tin, aluminum, and indium. Metal oxides such as silica, tin oxide, zinc oxide, titanium oxide, alumina, zirconia, indium oxide, antimony oxide, bismuth oxide, calcium oxide, antimony-doped tin oxide, tin-doped indium oxide, tin fluoride, Examples thereof include metal fluorides such as calcium fluoride and aluminum fluoride, and inorganic materials such as potassium titanate and boron nitride. These fine particles may be used alone or in combination with different ones. The average primary particle size of the fine particles is preferably 0.01 to 0.9 μm from the viewpoint of light transmittance and wear resistance, and more preferably 0.1 to 0.5 μm. The addition amount of the fine particles is preferably 0.1% by weight to 50% by weight, and preferably 5% by weight to 35% with respect to the total solid content contained in the protective layer, from the viewpoint of wear resistance and smoothness of the protective layer surface. Weight percent is more preferred.

As the binder resin, any binder resin used in the charge transport layer can be used, but polycarbonate and polyarylate are more preferable from the viewpoint of electrostatic characteristics and wear resistance. Moreover, it is also possible to use the above-mentioned polymer charge transporting material as a binder resin, which is favorable in achieving both wear resistance and electrostatic characteristics.
The protective layer preferably contains a charge transport material. As the charge transport material, any of the charge transport materials used in the above-described charge transport layer can be used.

  As the solvent used in forming these protective layers, tetrahydrofuran, dioxane, toluene, dichloromethane, monochlorobenzene, dichloroethane, cyclohexanone, methyl ethyl ketone, acetone, and the like can be used, and they can be used in combination. Moreover, you may add a plasticizer, a leveling agent, antioxidant, etc. to a protective layer. As a method for coating the protective layer, known methods such as a dip coating method, a spray coating method, a beat coat, a nozzle coat, a spinner coat, and a ring coat can be used, and the spray coating method is most suitable. 1-10 micrometers is suitable for the film thickness of a protective layer, and 2-6 micrometers is more preferable.

  After forming a protective layer on the outermost surface of the photoreceptor, the protective layer is brought into contact with the supercritical fluid and / or subcritical fluid, and treated with the supercritical fluid and / or subcritical fluid to be contained in the protective layer. Impurities contained in the charge transport material and the binder resin can be removed. Further, the coating solvent remaining in the layer when the protective layer is applied can be removed.

  In the present invention, 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, or an intermediate layer has an antioxidant, a plasticizer, a lubricant, and an ultraviolet absorption. Agents, low molecular charge transport materials and leveling agents can be added. Examples of these additives are shown below, but the present invention is 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) Others Silicone compounds, fluorine compounds, etc.

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.

Next, the image forming apparatus of the present invention will be described in detail with reference to the drawings.
FIG. 5 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. 5, a photoconductor 21 is the photoconductor described in FIGS. 1 to 4, and is contacted with a supercritical fluid and / or subcritical fluid after coating, and processed with the supercritical fluid and / or subcritical fluid. We are carrying out.

The photoconductor 21 has a drum shape, but may be a sheet shape or an endless belt shape. The charging charger 23, the pre-transfer charger 26, the transfer charger 29, the separation charger 30, and the pre-cleaning charger 32 include a roller-shaped charging member or a brush-shaped charging member in addition to a corotron, a scorotron, and a solid state charger (solid state charger). A charging member or the like 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. 6, the charging charger 23 is disposed close to the photosensitive member 21 via a gap, so that contaminants are less likely to adhere to the charging charger 23 or can be easily removed, thereby reducing the influence thereof. It can be used effectively in the present invention. In this case, the gap between the photoconductor 21 and the charging charger 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 photoconductor 21 may become unstable. In the present invention, charging stability is maintained by superimposing an alternating current component on a direct current component, thereby making it possible to simultaneously reduce the effects of ozone, the contamination of the charging charger 23, and the charging effect. By using in combination with the photoconductor 21 having high wear resistance, further high durability and high image quality can be realized.

  The light sources such as the image exposure unit 24 and the charge removal lamp 22 are all fluorescent materials such as fluorescent lamps, tungsten lamps, halogen lamps, mercury lamps, sodium lamps, light emitting diodes (LEDs), semiconductor lasers (LD), and electroluminescence (EL). 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. 5, the light source and the like are provided with a transfer step, a static elimination step, a cleaning step, a pre-exposure step and the like using light irradiation, so that the photosensitive member is irradiated 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-mentioned charger can be generally used, but a combination of a transfer charger and a separation charger as shown in FIG. 5 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 toner remaining on the photosensitive member 21 is also generated. Such toner is removed from the photoreceptor by the fur brush 33 or the blade 34. This cleaning process may be performed only with a cleaning brush or may be performed in combination with a blade, and a known cleaning brush such as a fur brush or a mag fur brush is used as the cleaning brush.
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. 7 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. 7, reference numerals (1C, 1M, 1Y, 1K) are drum-shaped photoconductors, and the photoconductor is the photoconductor 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. 7, 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. 7, 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, although the charging member is in contact with the photosensitive member in FIG. 7, by using a charging mechanism as shown in FIG. 6, 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 of the present invention shown in FIGS.

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

Example 1
After coating with an undercoat layer coating solution having the following composition on an aluminum plate support, drying was performed 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. Furthermore, 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 27 μm, and Photoconductor 1 was produced. In all cases, the blade coating method was used.
(Coating liquid for undercoat layer)
Titanium oxide CR-EL (manufactured by 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

ポリビニルブチラール（「ＸＹＨＬ」ＵＣＣ製）： ０．５部
メチルエチルケトン： １１０部
シクロヘキサノン： ２６０部 (Coating solution for charge generation layer)
Asymmetric bisazo pigment of the following structural formula: 2.5 parts

Polyvinyl butyral (“XYHL” manufactured by UCC): 0.5 part Methyl ethyl ketone: 110 parts Cyclohexanone: 260 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

シリコーンオイル（１００ｃｓ、信越化学工業社製）： ０．００２部 (Coating liquid for charge transport layer)
Polycarbonate Z polycarbonate (manufactured by Teijin Chemicals Ltd.): 10 parts Charge transport material represented by the following structural formula: 7 parts

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

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

  The photoreceptor obtained as described above was placed in a pressure vessel, carbon dioxide was selected as the supercritical fluid, and processing with the supercritical fluid was performed by the circulation method under the following conditions. Heating and pressurization were performed at room temperature and 0.10 MPa at a heating rate of 2-3 ° C./min and a pressurization rate of 0.2 MPa / min to 40 ° C. and 7 MPa. Here, with the flow rate set to 5.0 L / min (standard state conversion value), heating and pressurization are performed at a heating rate of 2 to 3 ° C./min and a pressurization rate of 10 MPa / min. Supercritical fluid. The treatment was performed for 5 hours while maintaining the flow rate at 5.0 L / min (standard state converted value). Thereafter, the flow rate is set to 1.0 to 3.0 L / min (converted to the standard state), and the pressure is reduced by cooling at a cooling rate of 2 to 3 ° C./min and a depressurization rate of 3 to 5 MPa / min. It returned to (1 atmosphere).

(Example 2)
In Example 1, after applying and drying the charge generation layer, a treatment with a supercritical fluid and / or a subcritical fluid is performed under the following conditions, and then a charge transport layer is formed in the same manner as in Example 1 to form a photoreceptor. 2 was produced. In addition, after application | coating of the electric charge transport layer, the process by a supercritical fluid and / or a subcritical fluid was not implemented. The treatment of the charge generation layer with the supercritical fluid and / or subcritical fluid was performed in the same manner as in Example 1 except that the set temperature of the supercritical fluid was changed to 60 ° C. and the set pressure was changed to 10 MPa.

(Example 3)
In Example 1, a subbing layer was applied on a conductive support and dried, followed by treatment with a supercritical fluid and / or subcritical fluid under the following conditions, and then the charge generation layer in the same manner as in Example 1. Then, a charge transport layer was formed to produce a photoreceptor 3. In addition, after application | coating of a charge generation layer and a charge transport layer, the process by a supercritical fluid and / or subcritical fluid was not implemented. The treatment of the undercoat layer with the supercritical fluid and / or subcritical fluid was performed in the same manner as in Example 1 except that the set temperature of the supercritical fluid was changed to 70 ° C. and the set pressure was changed to 20 MPa.

Example 4
In Example 1, a subbing layer was applied on a conductive support and dried, followed by treatment with a supercritical fluid and / or subcritical fluid under the following conditions, and then the charge generation layer in the same manner as in Example 1. After applying and drying, the treatment with the supercritical fluid and / or subcritical fluid is performed under the following conditions, and after the charge transport layer is applied and dried in the same manner as in Example 1, the supercritical fluid is treated under the following conditions. Then, the processing with the subcritical fluid was performed, and the photoreceptor 4 in which all of the undercoat layer, the charge generation layer, and the charge transport layer were processed with the supercritical fluid and / or the subcritical fluid was produced. The undercoat layer, the charge generation layer, and the charge transport layer were all treated with the supercritical fluid and / or subcritical fluid under the same conditions. The supercritical fluid was set to a temperature of 80 ° C. and the pressure set to 30 MPa. The rest was performed in the same manner as in Example 1.

(Comparative Example 1)
In Example 1, a photoconductor 5 was manufactured in the same manner as Example 1 except that no treatment with a supercritical fluid and / or a subcritical fluid was performed.

(Evaluation method and evaluation results)
The electrophotographic photosensitive member produced as described above was stored in an environment of 25 ° C. and 55% RH for 2 days after production, and then EPA-8200 (manufactured by Kawaguchi Electric Manufacturing Co., Ltd.) in an environment of 25 ° C. and 55% RH. ) And the electrophotographic characteristics were evaluated by a dynamic method. The photosensitive member is charged to 800 (−V), and then a monochromatic light of 655 nm is used to irradiate the surface of the photosensitive member to have an illuminance of ² μW / cm ² to obtain a light attenuation characteristic. Was evaluated as the initial residual potential. Thereafter, the forced fatigue test was carried out by repeating charging and exposure continuously under the conditions of illuminance 130 (lux) and discharge current value 116 (−μA), and after 5 minutes, 60 minutes and 120 minutes after forced fatigue. Similarly, residual potential was evaluated using EPA-8200. The results are shown in Table 1. A corotron was used as a charger used in the fatigue machine.
In addition, the electrophotographic photoreceptor produced in the same manner was stored in an environment of 25 ° C. and 50% RH for 20 days after production, and then evaluated in the same manner using EPA-8200. The results are shown in Table 2.

  As is clear from the above results, the residual potential is reduced by applying a supercritical fluid and / or a subcritical fluid after applying the photosensitive layer or the undercoat layer on the conductive support, It was confirmed that the residual potential increase due to electrostatic fatigue was also reduced. Furthermore, it has been found that the tendency is increased by treating the undercoat layer and the photosensitive layer with a supercritical fluid and / or a subcritical fluid. On the other hand, a photoreceptor that has not been processed with a supercritical fluid and / or subcritical fluid has a very large increase in residual potential due to forced deterioration, and the processing with a supercritical fluid and / or subcritical fluid is effective. It became clear. Further, even if the evaluation result after 20 days is seen, the residual potential is lower in the photoconductor subjected to the processing with the supercritical fluid and / or the subcritical fluid, and this tendency is maintained. Further, when comparing the results evaluated after 2 days and the results evaluated after 20 days, the photoconductor subjected to the processing is more preferable than the photoconductor not processed with the supercritical fluid and / or the subcritical fluid. It was found that the change with time was small and the stability with time was high after the photoconductor was produced.

ポリカーボネート（Ｚポリカ、帝人化成製）： １０部
テトラヒドロフラン： ２２０部
シクロヘキサノン： ８０部 (Example 5)
In Example 1, a protective layer of about 3 μm was formed on the charge transport layer using a protective layer coating solution having the following composition, followed by drying at 140 ° C. for 20 minutes to prepare Photoreceptor 5. Spray coating was used to apply the protective layer. The photoconductor obtained as described above was put in a pressure vessel, and the supercritical fluid was processed in the same manner as in Example 1 except that the supercritical fluid was set to a temperature of 80 ° C. and the pressure was set to 20 MPa. went. The obtained photoreceptor was used and evaluated in the same manner as in Example 1. The results are shown in Tables 3 and 4.
(Coating liquid for protective layer)
Fluororesin fine particles (Lublon L-2, manufactured by Daikin Industries, Ltd.): 1 part Charge transport material having the following structural formula: 7 parts

Polycarbonate (Z Polyca, Teijin Chemicals): 10 parts Tetrahydrofuran: 220 parts Cyclohexanone: 80 parts

(Comparative Example 2)
In Comparative Example 1, a protective layer was formed on the charge transport layer using the protective layer coating solution described in Example 5 in the same manner as in Example 5, and Photoreceptor 7 was produced. In addition, after forming a protective layer, the process by a supercritical fluid was not performed at all. The obtained photoreceptor was used and evaluated in the same manner as in Example 1. The results are shown in Tables 3 and 4.

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 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.

Explanation of symbols

1C, 1M, 1Y, 1K Photoconductor 2C, 2M, 2Y, 2K Charging member 3C, 3M, 3Y, 3K Laser light 4C, 4M, 4Y, 4K Developing member 5C, 5M, 5Y, 5K Cleaning member 6C, 6M, 6Y , 6K image forming element 11C, 11M, 11Y, 11K transfer brush 21 photoconductor 22 static elimination lamp 23 charging charger 24 image exposure unit 25 developing unit 26 pre-transfer charger 27 registration roller 28 transfer paper 29 transfer charger 30 separation charger 31 separation claw 32 Charger before cleaning 33 Far brush 34 Blade 101 Drum 102 Contact charging device 103 Image exposure 104 Developing device 105 Transfer body 106 Contact transfer device 107 Cleaning unit

Claims (6)

  In a method for producing an electrophotographic photosensitive member having at least a charge generating material, a charge transporting material and a binder resin as main components on a conductive support, the photosensitive layer is formed on the conductive support. After the formation of the electrophotographic photosensitive member, the photosensitive layer is brought into contact with supercritical carbon dioxide and / or subcritical carbon dioxide.   In a method for producing an electrophotographic photosensitive member having at least 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 on the conductive support. After forming the charge generation layer on the support, the charge generation layer and / or after forming the charge transport layer on the charge generation layer, the charge transport layer is supercritical carbon dioxide and / or subcritical carbon dioxide. And a method for producing an electrophotographic photosensitive member, wherein   In the method for producing an electrophotographic photosensitive member in which an undercoat layer is formed on a conductive support, and further a single-layer photosensitive layer or a charge generation layer and a charge transport layer are formed, the conductive support is formed on the conductive support. A method for producing an electrophotographic photoreceptor, comprising forming an undercoat layer and then contacting at least the undercoat layer with supercritical carbon dioxide and / or subcritical carbon dioxide.   In the method for producing an electrophotographic photosensitive member in which a protective layer is formed on the outermost surface of the electrophotographic photosensitive member, at least after the protective layer is formed, the protective layer is contacted with supercritical carbon dioxide and / or subcritical carbon dioxide. A method for producing an electrophotographic photoreceptor, characterized by comprising: The method for producing an electrophotographic photosensitive member according to any one of claims 1 to 4, characterized in that circulating the supercritical carbon dioxide and / or subcritical carbon dioxide.   The supercritical carbon dioxide and / or subcritical carbon dioxide contains a substance other than the binder resin contained in the layer brought into contact with the supercritical carbon dioxide and / or subcritical carbon dioxide in advance. The method for producing an electrophotographic photosensitive member according to any one of 1 to 5.

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