JP4097658B2 - Electrophotographic photosensitive member, electrophotographic method, electrophotographic apparatus, and process cartridge for electrophotographic apparatus - Google Patents

Description

  The present invention relates to an electrophotographic photosensitive member, an electrophotographic method using the electrophotographic photosensitive member, and the like. Specifically, the electrophotographic photosensitive member particularly suitable for use in a contact charging method, and an electrophotographic method using the same. The present invention relates to an electrophotographic apparatus and a process cartridge for an electrophotographic apparatus.

  As the electrophotographic method, the Carlson process and various deformation processes thereof are known, and are widely used in copying machines, printers, and the like. Among the photoreceptors used in such electrophotographic methods, those using organic photosensitive materials have begun to be used in recent years due to advantages such as low cost, mass productivity, and non-pollution.

  Organic electrophotographic photoreceptors include photoconductive resins represented by polyvinylcarbazole (PVK), charge transfer complex types represented by PVK-TNF (2,4,7-trinitrofluorenone), phthalocyanine-binders Are known, such as a pigment dispersion type, a function separation type photoreceptor using a combination of a charge generation material and a charge transport material, and the function separation type photoreceptor is attracting attention.

  The mechanism of electrostatic latent image formation in this function-separated type photoreceptor is that when the photoreceptor is charged and irradiated with light, the light passes through the transparent charge transport layer and is absorbed by the charge generation material in the charge generation layer, The charge-generating substance that has absorbed the light generates charge carriers, which are injected into the charge transport layer, move in the charge transport layer according to the electric field generated by the charge, and neutralize the charge on the surface of the photoreceptor. Thus, an electrostatic latent image is formed. In the function-separated type photoreceptor, it is known and useful to use a combination of a charge transport material having absorption mainly in the ultraviolet region and a charge generation material having absorption mainly in the visible region.

  Many charge transport materials have been developed as low molecular weight compounds. However, since low molecular weight compounds do not have film-forming properties alone, they are usually dispersed and mixed in an inert polymer. However, the charge transport layer composed of a low molecular charge transport material and an inert polymer is generally soft, and has a drawback that film abrasion due to repeated use tends to occur in the Carlson process.

  In recent years, there have been remarkable developments in electrophotographic processes using the above-described photoreceptor, and various improvements have been made over the conventional Carlson process. For example, an improvement in a cleaning method for leaving no copy history (see, for example, Patent Document 1), an improvement in a charging method for reducing the amount of ozone generated (for example, Patent Document 2, Patent Document 3, Patent Document 4, Patent Literature 5, Patent Literature 6, and Patent Literature 7), and improvement of a transfer method for improving image quality (for example, see Patent Literature 8 and Patent Literature 9).

  In particular, the contact charging system is becoming more popular in the charging system due to improvements in the problems of ozone and NOx that occur compared to the conventional charger system and the improvement of charging unevenness. Furthermore, in the case of organic photoreceptors, the contact charging method has a high charging efficiency, the generation amount of corona products is extremely small, the occurrence of image defects such as image blurring is suppressed, and the durability of the photoreceptor is increased. It is valid.

However, since such a contact charging method applies a voltage directly to the photoconductor, discharge breakdown of the photoconductor tends to occur, and in the case of reversal development, image defects such as black spot images tend to occur. In order to prevent discharge destruction of the photoreceptor due to such contact charging, a contact charging device using a photoreceptor in which particles having a maximum particle size of 1 μm or less are contained in the photoreceptor and combining the photoreceptor with a contact charging method. (For example, see Patent Document 10) has been proposed, but the fact is that the effect is not sufficient only by defining the maximum diameter of the particles contained in the photoreceptor. Further, an image forming apparatus (for example, refer to Patent Document 11) using a photoconductor provided with a charge injection layer on a photoconductive layer and combining the photoconductor and a contact charging method has been proposed. Since the charge injection layer needs to have a gradient in the volume resistance value in the thickness direction, it is difficult to produce a photoreceptor.
JP 58-102273 A JP-A-56-104351 JP-A-57-178267 JP 58-40566 A JP 58-139156 A JP 58-150975 A JP-A 63-149669 JP-A-5-45916 JP-A-7-152217 Japanese Patent No. 2614282 JP-A-9-73212

  SUMMARY OF THE INVENTION An object of the present invention is to provide an electrophotographic photosensitive member that prevents black spot images seen in reversal development due to discharge breakdown of the photosensitive member when a contact charging method is employed. Another object of the present invention is to provide an electrophotographic method, an electrophotographic apparatus, and a process cartridge for an electrophotographic apparatus using the electrophotographic photosensitive member.

According to a first aspect of the present invention, there is provided an electrophotographic method in which an electrophotographic photosensitive member is charged and exposed, developed and transferred to form an image. ¹² It has an outermost layer in which particles of Ωcm or more and a diameter of 0.1 μm or more and 5.0 μm or less are dispersed and contained in a polyarylate resin, and the dispersed and contained particles are dispersed silicone oil, and the charge is contact charging This is an electrophotographic method characterized by the following method.
A second aspect of the present invention is an electrophotographic apparatus provided with an electrophotographic photosensitive member and a charging unit, an exposing unit, a developing unit, and a transferring unit, wherein the photosensitive unit has a volume resistance of 1 × 10. ¹² It has an outermost layer in which particles of Ωcm or more and a diameter of 0.1 μm or more and 5.0 μm or less are dispersed and contained in a polyarylate resin, and the dispersed and contained particles are dispersed silicone oil, and the charge is contact charging This is an electrophotographic apparatus characterized by that.
According to a third aspect of the present invention, there is provided a process cartridge for an electrophotographic apparatus comprising at least an electrophotographic photosensitive member and employing a contact charging method, wherein the photosensitive member has a volume resistance of 1 × 10. ¹² An electrophotographic apparatus having an outermost layer in which particles of Ωcm or more and a diameter of 0.1 μm or more and 5.0 μm or less are dispersed and contained in a polyarylate resin, and wherein the dispersed and contained particles are a dispersed silicone oil Process cartridge.

According to the first aspect of the present invention, it is possible to provide an electrophotographic method using an electrophotographic photosensitive member that prevents a black spot image seen in reversal development due to discharge breakdown of the photosensitive member when the contact charging method is adopted. it can.
  According to the second aspect of the present invention, it is possible to provide an electrophotographic apparatus using an electrophotographic photosensitive member for preventing a black spot image seen in reversal development due to discharge breakdown of the photosensitive member when the contact charging method is adopted. it can.
  According to a third aspect of the present invention, there is provided a process cartridge for an electrophotographic apparatus using an electrophotographic photosensitive member for preventing black spot images seen in reversal development due to discharge breakdown of the photosensitive member when a contact charging method is employed. can do.

  In order to achieve the above-mentioned problems, the present inventors have repeatedly studied the electrophotographic photosensitive member from various angles. As a result, the specific resistance of the photosensitive layer of the photosensitive member placed in contact with the contact charging member is more than a certain value. In addition, it has been found that the discharge breakdown can be effectively prevented without side effects by dispersing and containing particles having a constant particle size. The present invention has been made based on this.

According to the present invention, firstly, an electrophotographic photosensitive member particularly useful for a contact charging method, comprising particles having a volume resistance of 1 × 10 ¹² Ωcm or more and a diameter of 0.1 μm or more dispersed. A featured electrophotographic photoreceptor is provided.

Second, in an electrophotographic method in which an electrophotographic photosensitive member is charged and subjected to exposure, development, and transfer to form an image, the photosensitive member contains particles having a volume resistance of 1 × 10 ¹² Ωcm or more and a diameter of 0.1 μm or more. An electrophotographic method is provided which is dispersed and contained, and wherein the charging is a contact charging method.

Third, in an electrophotographic apparatus provided with an electrophotographic photoreceptor and charging means, exposure means, developing means, and transfer means, the photoreceptor disperses particles having a volume resistance of 1 × 10 ¹² Ωcm or more and a diameter of 0.1 μm or more. There is provided an electrophotographic method characterized in that it is contained and the charging is a contact charging system.

Fourth, a process cartridge for an electrophotographic apparatus having at least an electrophotographic photosensitive member and adopting a contact charging method, wherein the photosensitive member disperses particles having a volume resistance of 1 × 10 ¹² Ωcm or more and a diameter of 0.1 μm or more. There is provided a process cartridge for an electrophotographic apparatus characterized by containing the electrophotographic apparatus.

  According to the invention of the present application, the abrasion of the outermost surface of the photoreceptor in repeated use can be improved at a low cost without affecting the electrostatic characteristics. As a result, a long-term stable image can be obtained.

Hereinafter, the present invention will be described in more detail. According to the knowledge of the present inventors, the discharge breakdown of the photoreceptor due to contact charging is caused by the low-resistance particles contained in the photosensitive layer, or the metal foreign matter incorporated in the production process and their aggregates, that is, the subbing. Aggregates of resistance control materials contained in layers, intermediate layers, aggregates of charge generation materials contained in charge generation layers, aggregates of additives and resistance control materials contained in charge transport layers, protective layers, etc. Chips of support cutting included in the process and foreign matters of cutting powder from the apparatus sliding part are caused as a nucleus. In the present invention, even if the above-mentioned aggregates or foreign matters that cause discharge breakdown in contact charging are mixed, the volume resistance is 1 × 10 ¹² Ωcm or more and the diameter is 0.1 μm or more in the photosensitive layer or protective layer. By containing particles in a dispersed manner, it is possible to increase the pressure resistance of the photosensitive layer, and it is possible to prevent discharge breakdown that is a problem with contact charging.

  The particles used in the present invention have a particle size of 0.1 μm or more, preferably 0.1 to 5.0 μm. If it is smaller than 0.1 μm, the effect of addition is poor, and if it exceeds 5.0 μm, the residual potential may increase. These particles may be dispersed in either the photosensitive layer or the protective layer when a protective layer is provided on the surface, but it is most effective to add to the uppermost layer (surface layer). is there. Here, the surface layer is a surface layer if a protective layer is provided on the photosensitive layer, and is a surface layer if there is no protective layer and the photosensitive layer is exposed. In addition, the photosensitive layer is a laminate of a charge generation layer and a charge transport layer, and the charge transport layer is a surface layer when the protective layer is not provided on the surface side of the charge transport layer.

Particles having a volume resistance of 1 × 10 ¹² Ωcm or more and a diameter of 0.1 μm used in the present invention include curable resin fine powders such as silicone resin, melamine resin, urea resin, acrylic resin, styrene resin; titanium oxide, Metal oxide fine powders such as aluminum oxide and tin oxide; solid lubricants such as polytetrafluoroethylene, polychlorotrifluoroethylene, polyvinylidene fluoride, zinc stearate, aluminum stearate; dimethyl silicone oil, methylphenyl silicone oil, Methyl hydrogen polysiloxane, cyclic dimethyl polysiloxane, alkyl-modified silicone oil, polyether-modified silicone oil, alcohol-modified silicone oil, fluorine-modified silicone oil, amino-modified silicone oil, mercapto-modified silicone Oil, epoxy-modified silicone oil, carboxyl-modified silicone oil, silicone oils such as higher fatty acid-modified silicone oil.

  Such particles are contained in a dispersed state in the photosensitive layer, preferably the surface layer. By dispersing such highly resistant particles in the photosensitive member, the withstand voltage of the photosensitive member is increased against the applied pressure. It is considered that the occurrence of black spots can be suppressed. The content of the particles is 0.05 to 5% by weight, preferably 0.1 to 1% by weight, based on the layer in which the particles are dispersed. If the particle content exceeds 5% by weight, the residual potential increases, which is a problem. Conversely, if the particle content is less than 0.05% by weight, discharge breakdown is likely to occur when contact charging is performed.

  Next, the electrophotographic photosensitive member of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing a configuration example of a photoconductor used in the present invention, in which a photoconductive layer 35 is formed on a conductive support 31. FIG. 2 is a diagram illustrating another configuration example, in which the photosensitive layer 35 on the conductive support 31 is configured by a stacked type of a charge generation layer 37 and a charge transport layer 39. FIG. 3 is a diagram showing still another configuration example, in which an intermediate layer 33 is provided between the photosensitive layer 35 and the conductive support 31. Also in this case, the photosensitive layer 35 may have a single layer structure or a stacked structure including a charge generation layer 37 and a charge transport layer 39. FIG. 4 is a view showing still another configuration example, in which a photosensitive layer 35 and a protective layer 34 are formed on a conductive support 31. In this case, the photosensitive layer 35 may be a single-layer photosensitive layer or a laminated photosensitive layer.

Next, the configuration of the electrophotographic photosensitive member will be described. Examples of the conductive support 31 include those having a volume resistance of 10 ¹⁰ Ω or less, such as metals such as aluminum, nickel, chromium, nichrome, copper, silver, gold, and platinum, and oxides such as tin oxide and indium oxide. Are coated with a film or cylindrical plastic, paper or the like by vapor deposition or sputtering, or a plate made of aluminum, aluminum alloy, nickel, stainless steel, etc. I. , I. I. , Pipes that have been surface-treated by cutting, superfinishing, polishing, etc. after being made into bare pipes by methods such as extrusion and drawing can be used.

  The photosensitive layer 35 in the present invention may be a single layer type or a multilayer type, but here, for convenience of explanation, a multilayer type will be described first. First, the charge generation layer 37 will be described. The charge generation layer 37 is a layer mainly composed of a charge generation material, and a binder resin may be used as necessary. As the charge generation material, inorganic materials and organic materials can be used.

  Inorganic materials include crystalline selenium, amorphous selenium, selenium-tellurium, selenium-tellurium-halogen, selenium-arsenic compounds, amorphous silicon, and the like. In amorphous silicon, dangling bonds terminated with hydrogen atoms or halogen atoms, or doped with boron atoms, phosphorus atoms or the like are preferably used.

  On the other hand, a known material can be used as the organic material. For example, phthalocyanine pigments such as metal phthalocyanine and metal-free phthalocyanine, azulenium salt pigments, methine pigments with squaric acid, azo pigments with carbazole skeleton, azo pigments with triphenylamine skeleton, azo pigments with diphenylamine skeleton, dibenzothiophene skeleton Azo pigments having a fluorenone skeleton, azo pigments having an oxadiazole skeleton, azo pigments having a bisstilbene skeleton, azo pigments having a distyryl oxadiazole skeleton, azo pigments having a distyrylcarbazole skeleton Pigments, anthraquinone or polycyclic quinone pigments, quinoneimine pigments, diphenylmethane and triphenylmethane pigments, benzoquinone and naphthoquinone pigments, cyanine and azomethine pigments, Jigoido based pigments, and bisbenzimidazole pigments. These charge generation materials can be used alone or as a mixture of two or more.

  As the binder resin used as necessary, polyamide, polyurethane, epoxy resin, polyketone, polycarbonate, silicone resin, acrylic resin, polyvinyl butyral, polyvinyl formal, polyvinyl ketone, polystyrene, poly-N-vinylcarbazole, polyacrylamide, etc. are used. It is done. These binder resins can be used alone or as a mixture of two or more. Moreover, you may add the below-mentioned charge transport substance as needed.

  Methods for forming the charge generation layer 37 include a vacuum thin film manufacturing method and a casting method from a solution dispersion system. For the former method (vacuum thin film preparation method), a vacuum deposition method, a glow discharge decomposition method, an ion plating method, a sputtering method, a reactive sputtering method, a CVD method or the like is used. System materials and organic materials can be formed satisfactorily. In order to provide the charge generation layer by the latter method (casting method), the inorganic or organic charge generation material described above is used together with a binder resin, if necessary, using a solvent such as tetrahydrofuran, cyclohexanone, dioxane, dichloroethane, or butanone. It can be formed by dispersing with a ball mill, adrider, sand mill or the like and applying the solution after diluting the dispersion appropriately. The coating can be performed using a dip coating method, a spray coating method, a bead coating method, or the like.

  The thickness of the charge generation layer provided as described above is suitably about 0.01 to 5 μm, preferably 0.05 to 2 μm.

  Next, the charge transport layer 39 will be described. The charge transport layer 39 can be formed by dissolving or dispersing a charge transport material and a binder resin in an appropriate solvent, and applying and drying the solution. Moreover, a plasticizer and a leveling agent can also be added as needed. Charge transport materials include electron transport materials and hole transport materials.

  Examples of the electron transporting 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] thiophene-4-one, 1,3,7-trinitro Examples thereof include electron accepting substances such as dibenzothiophene-5,5-dioxide. These electron transport materials can be used alone or as a mixture of two or more.

  Examples of the hole transporting material include the electron donating materials shown below and are used favorably. For example, oxazole derivatives, oxadiazole derivatives, imidazole derivatives, triphenylamine derivatives, 9- (p-diethylaminostyrylanthracene), 1,1-bis- (4-dibenzylaminophenyl) propane, styrylanthracene, styrylpyrazirine , Phenylhydrazones, α-phenylstilbene derivatives, thiazole derivatives, triazole derivatives, phenazine derivatives, acridine derivatives, benzofuran derivatives, benzimidazole derivatives, thiophene derivatives, and the like. These hole transport materials can be used alone or as a mixture of two or more.

The binder resin used in the charge transporting layer 39, a polycarbonate (Bisufu E Nord A type, Bisufu E Nord Z type), polyester, methacrylic resin, acrylic resin, polyethylene, vinyl chloride, vinyl acetate, polystyrene, phenol resins, epoxy resins Polyurethane, polyvinylidene chloride, alkyd resin, silicon resin, polyvinyl carbazole, polyvinyl butyral, polyvinyl formal, polyacrylate, polyacrylamide, phenoxy resin, and the like are used.

  In addition, a polymer charge transport material having any function of a binder resin and a charge transport material can be used as the binder resin. Examples of the polymer charge transport material used in this case include the following.

  (A) Polymer having a carbazole ring in the main chain and / or side chain, for example, poly-N-vinylcarbazole, Japanese Patent Laid-Open No. 50-82056, Japanese Patent Laid-Open No. 54-9632, Japanese Patent Laid-Open No. 54-11737 And the compounds described in JP-A-4-183719.

  (B) Polymers having a hydrazine structure in the main chain and / or side chain, for example, compounds described in JP-A-57-78402 and JP-A-3-50555 are exemplified.

  (C) Polysilylene polymers For example, the compounds described in JP-A-63-285552, JP-A-5-19497, and JP-A-5-70595 are exemplified.

  (D) Polymer having tertiary amine structure in main chain and / or side chain, for example, N, N-bis (4-methylphenyl) -4-aminopolystyrene, JP-A-1-13061, JP-A-1 -19049, JP-A-1-1728, JP-A-1-105260, JP-A-2-167335, JP-A-5-66598, JP-A-5-40350, and the like. Illustrated.

  (E) Other polymers Examples include, for example, formaldehyde condensation polymers of nitropyrene, compounds described in JP-A Nos. 51-73888 and 56-150749, and the like.

  The polymer charge transporting material used in the present invention is not limited to the above-mentioned polymer, but also a copolymer of known monomers, a block polymer, a graft polymer, a star polymer, and for example, JP-A-3-109406. It is also possible to use a cross-linked polymer having an electron donating group as disclosed in Japanese Patent Publication No. Gazette. The thickness of the charge transport layer 19 is suitably about 5 to 100 μm. In the present invention, a plasticizer or a leveling agent may be added to the charge transport layer 19.

  As a plasticizer, what is used as a plasticizer of general resins, such as dibutyl phthalate and dioctyl phthalate, can be used as it is, and the amount used is suitably about 0 to 30% by weight with respect to the binder resin. As the leveling agent, a polymer or oligomer having a perfluoroalkyl group in the side chain is used, and the amount used is suitably about 0 to 1% by weight based on the binder resin.

  Next, the case where the photosensitive layer 35 has a single layer structure will be described. In the case of providing a single-layer photosensitive layer by the casting method, there are many functionally separated types composed of a charge generating material and a charge transport material. That is, the above materials can be used for the charge generation material and the charge transport material. The single-layer photosensitive layer can be formed by dissolving or dispersing a charge generating substance, a charge transporting substance, and a binder resin in an appropriate solvent, and applying and drying them. Moreover, a plasticizer and a leveling agent can also be added as needed. As the binder resin, the binder resin previously mentioned in the charge transport layer 19 may be used as it is, or the binder resin mentioned in the charge generation layer 17 may be mixed and used.

  A single-layer photosensitive layer is prepared by dispersing a charge generating substance, a charge transporting substance, and a binder resin using a solvent such as tetrahydrofuran, cyclohexanone, dioxane, dichloroethane, butanone, etc. with a ball mill, an adrider, a sand mill, etc. Can be formed by coating. The coating can be performed using a dip coating method, a spray coating method, a bead coating method, or the like. The single-layer photosensitive layer is prepared by adding a charge transport material to a eutectic complex formed from a pyrylium dye and a bisphenol A polycarbonate, and dispersing the dispersion in a suitable solvent. Can be formed. The film thickness of the single-layer photoreceptor is suitably about 5 to 100 μm.

  In the electrophotographic photoreceptor used in the present invention, an intermediate layer 33 can be provided between the conductive support 31 and the photosensitive layer 35 (charge generation layer 37 in the case of a laminated type). The intermediate layer 33 improves adhesiveness, prevents moire, and improves the coatability of the upper layer. It is provided for the purpose of reducing the residual potential. The intermediate layer generally contains a resin as a main component. However, considering that the photosensitive layer is applied on the resin layer with a solvent, the intermediate layer is preferably a resin having a high solubility resistance with respect to a general organic solvent.

  Examples of the resin used in such an intermediate layer include water-soluble resins such as polyvinyl alcohol, casein, and sodium polyacrylate, alcohol-soluble resins such as copolymer nylon and methoxymethylated nylon; polyurethane, melamine resin, alkyd-melamine resin And a curable resin that forms a three-dimensional network structure such as an epoxy resin. Further, fine powders such as metal oxides exemplified by titanium oxide, silica, alumina, zirconium oxide, tin oxide, indium oxide and the like, or metal sulfides and metal nitrides may be added. These intermediate layers can be formed using an appropriate solvent and coating method as in the above-mentioned photosensitive layer.

Furthermore, a metal oxide layer formed by, for example, a sol-gel method using a silane coupling agent, a titanium coupling agent, a chromium coupling agent, or the like is also useful as the intermediate layer of the present invention. In addition to this, the intermediate layer of the present invention is formed by anodizing Al ₂ O ₃ , organic matter such as polyparaxylylene (parylene), SiO, SnO ₂ , TiO ₂ , ITO, CeO _2, etc. Those provided with an inorganic material by a vacuum thin film manufacturing method can also be used favorably. The thickness of the intermediate layer is suitably from 0 to 5 μm.

  The protective layer 34 is a layer provided for the purpose of protecting the photoreceptor surface. The protective layer 34 can be formed by dissolving or dispersing a polymer charge transport material in a suitable solvent such as tetrahydrofuran, dioxane, toluene, monochlorobenzene, dichloroethane, methylene chloride, cyclohexanone, and applying and drying. In addition to using the above-described polymer charge transporting material, an electrically inactive binder resin can be used for the protective layer. Materials used for this include ABS resin, ACS resin, olefin-vinyl monomer copolymer, chlorinated polyether, allyl resin, polyacetal, polyamide, polyamideimide, polyacrylate, polyallylsulfone, polybutylene, polybutylene terephthalate, Polycarbonate, polyethersulfone, polyethylene, polyethylene terephthalate, polyimide, acrylic resin, polymethylpentene, polypropylene, polyphenylene oxide, polysulfone, polystyrene, AS resin, butadiene-styrene copolymer, polyurethane, polyvinyl chloride, epoxy resin, etc. Among these, the hardened | cured material of a curable material and a hardening | curing agent is mentioned. Among them, the polycarbonate having the structure of the above formula (1), (2) or (3) is used effectively in the repeating unit.

  In addition, a filler material can be added to the protective layer for the purpose of improving wear resistance. Examples of the organic filler material include fluororesin powder such as polytetrafluoroethylene, silicone resin powder, a-carbon powder, etc., and inorganic filler material includes metal powder such as copper, tin, aluminum, indium, Examples thereof include metal oxides such as tin oxide, zinc oxide, titanium oxide, indium oxide, antimony oxide, bismuth oxide, antimony-doped tin oxide, tin-doped indium oxide, and inorganic materials such as potassium titanate. These filler materials may be used alone or in combination of two or more. These filler materials can be dispersed by using an appropriate disperser in the protective layer coating solution. Moreover, it is preferable from the point of the transmittance | permeability of a protective layer that the average particle diameter of a filler is 0.5 micrometer or less, Preferably it is 0.2 micrometer or less.

  In the present invention, a plasticizer or a leveling agent may be added to the protective layer 39. As the plasticizer and leveling agent, the materials specified in the charge transport layer can be used as they are. As a method for forming the protective layer, a normal coating method is employed. In addition, about 0.5-10 micrometers is suitable for a film thickness.

  In the electrophotographic photoreceptor of the present invention, the particles may be added and dispersed in each layer, but are preferably added and dispersed in the outermost layer. Therefore, it is desirable that the particles are dispersed in at least the protective layer in the photoreceptor having the protective layer. This reduces the surface energy of the outermost layer and improves wear resistance. Further, as described above, it can be added to the protective layer and the layer closer to the support, which is effective.

  In the present invention, an antioxidant may be added for the purpose of preventing the decrease in sensitivity and the increase in residual potential, in order to improve environmental resistance. The antioxidant may be added to any layer containing an organic substance, but good results are obtained when it is added to a layer containing a charge transport material. The following are mentioned as antioxidant which can be used for this invention.

(Monophenol compound)
2,6-di-t-butyl-p-cresol, butylated hydroxyanisole, 2,6-di-t-butyl-4-ethylphenol, stearyl-β- (3,5-di-t-butyl-4 -Hydroxyphenyl) propionate and the like.

(Bisphenol compounds)
2,2′-methylene-bis- (4-methyl-6-tert-butylphenol), 2,2′-methylene-bis- (4-ethyl-6-tert-butylphenol), 4,4′-thiobis- ( 3-methyl-6-t-butylphenol), 4,4′-butylidenebis- (3-methyl-6-t-butylphenol) and the like.

(High molecular phenolic compounds)
1,1,3-tris- (2-methyl-4-hydroxy-5-tert-butylphenyl) butane, 1,3,5-trimethyl-2,4,6-tris (3,5-di-t- Butyl-4-hydroxybenzyl) benzene, tetrakis- [methylene-3- (3 ′, 5′-di-t-butyl-4′-hydroxydiphenyl) propionate] methane, bis [3,3′-bis (4 '-Hydroxy-3'-t-butylphenyl) butyric acid] glycol ester, tocopherols and the like.

(Paraphenylenediamines)
N-phenyl-N'-isopropyl-p-phenylenediamine, N, N'-di-sec-butyl-p-phenylenediamine, N-phenyl-N-sec-butyl-p-phenylenediamine, N, N'- Diisopropyl-p-phenylenediamine, N, N′-dimethyl-N, N′-di-t-butyl-p-phenylenediamine and the like.

(Hydroquinones)
2,5-di-t-octylhydroquinone, 2,6-didodecylhydroquinone, 2-dodecylhydroquinone, 2-dodecyl-5-chlorohydroquinone, 2-t-octyl-5-methylhydroquinone, 2- (2-octadecenyl) ) -5-methylhydroquinone, etc.
(Organic sulfur compounds)
Dilauryl-3,3′-thiodipropionate, distearyl-3,3′-thiodipropionate, ditetradecyl-3,3′-thiodipropionate, and the like.

(Organic phosphorus compounds)
Triphenylphosphine, tri (nonylphenyl) phosphine, tri (dinonylphenyl) phosphine, tricresylphosphine, tri (2,4-dibutylphenoxy) phosphine, and the like.

  These compounds are known as antioxidants such as rubbers, plastics, oils and fats, and commercially available products can be easily obtained. The addition amount of the antioxidant in the present invention is 01 to 100 parts by weight, preferably 2 to 30 parts by weight with respect to 100 parts by weight of the charge transport material.

  Next, the electrophotographic method and the electrophotographic 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 electrophotographic apparatus of the present invention, and the following modifications also belong to the category of the present invention. In FIG. 5, a photosensitive member 1 is provided with a photosensitive layer of the present invention on a conductive support, and a contact charging member 3 is disposed in contact with the photosensitive member. If necessary, a pre-transfer charger 7, a transfer charger 10, a separation charger 11, and a pre-cleaning charger 13 are arranged. These units include a corotron, a scorotron, a solid state charger, a roller, a belt. Well-known means including the above are used.

  As the transfer means, the above charger can be generally used. However, as shown in the figure, a combination of a transfer charger and a separation charger is effective.

  The light source such as the image exposure unit 5 and the charge removal lamp 2 emits light such as a fluorescent lamp, a tungsten lamp, a halogen lamp, a mercury lamp, a sodium lamp, a light emitting diode (LED), a semiconductor laser (LD), and an electroluminescence (EL). All things can be used. Various types of filters such as a sharp cut filter, a band pass filter, a near infrared cut filter, a dichroic filter, an interference filter, and a color temperature conversion filter can be used to irradiate only light in a desired wavelength range.

  Such a light source or the like irradiates the photoreceptor with light by providing a transfer process, a negative electrode process, a cleaning process, or a pre-exposure process using light irradiation in addition to the process shown in FIG.

  The toner developed on the photosensitive member 1 by the developing unit 6 is transferred to the transfer paper 9, but not all is transferred, and some toner remains on the photosensitive member 1. Such toner is removed from the photoreceptor by the fur brush 14 and the blade 15. Cleaning may be performed only with a cleaning brush, and a known brush such as a fur brush or a mag fur brush is used as the cleaning brush. 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.

  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 the one shown in FIG. The photoreceptor 16 is a member having the photosensitive layer of the present invention on a conductive support (desirably containing specific particles dispersed in the outermost layer).

  EXAMPLES Next, although an Example demonstrates this invention further in detail, this invention is not limited to a following example. In addition, all the parts used in an Example represent a weight part.

Example 1
On an aluminum cylindrical support having a diameter of 30 mm, an intermediate layer coating solution, a charge generation layer coating solution, and a charge transport layer coating solution having the following composition were sequentially applied and dried to a thickness of about 3.5 μm. An intermediate layer, a charge generation layer having a thickness of about 0.3 μm, and a charge transport layer having a thickness of about 20 μm were formed to produce the electrophotographic photosensitive member of the present invention.

(Intermediate layer coating solution)
375 parts of alkyd resin solution (manufactured by Dainippon Ink & Chemicals, Inc .: Beckolite M-6401-50)
210 parts of melamine resin solution (Dainippon Ink Chemical Co., Ltd .: Super Becamine G821-60)
Titanium dioxide (manufactured by Ishihara Sangyo Co., Ltd .: Taipei CR-EL) 1250 parts 2-butanone 7800 parts (coating liquid for charge generation layer)
TiOPc pigment powder 3 parts Polyvinyl butyral 2 parts Tetrahydrofuran 50 parts 4-methyl-2-pentanone 90 parts (Coating liquid for charge transport layer)
Polyarylate resin 10 parts Charge transport material with the following structure 7 parts

メチルフェニルポリシロキサン ０．１５部 （信越シリコーン社製：ＫＦ５６）
塩化メチレン ９０部
参考例２
実施例１の電荷輸送層用塗工液を下記組成の電荷輸送層用塗工液に変更した以外は、実施例１と同様に電子写真感光体を作製した。なお、電荷輸送層用塗工液はビーズミルにて３時間分散して作成した。

Methylphenylpolysiloxane 0.15 parts (manufactured by Shin-Etsu Silicone: KF56)
90 parts of methylene chloride
Reference example 2
An electrophotographic photosensitive member was produced in the same manner as in Example 1, except that the charge transport layer coating solution of Example 1 was changed to a charge transport layer coating solution having the following composition. The charge transport layer coating solution was prepared by dispersing in a bead mill for 3 hours.

(Coating liquid for charge transport layer)
10 parts of acetophenone polycarbonate 7 parts of charge transport material with the following structure

酸化チタン微粉末（石原産業社製：Ａ−１００） ０．１２部
塩化メチレン ９０部

Titanium oxide fine powder (Ishihara Sangyo Co., Ltd .: A-100) 0.12 parts Methylene chloride 90 parts

Reference example 3
An electrophotographic photosensitive member was produced in the same manner as in Example 1 except that the charge transport layer coating solution in Example 1 was changed to a charge transport layer coating solution having the following composition.
(Coating liquid for charge transport layer)
Charge transport material 7 parts of bis phenol A type polycarbonate 10 parts following structure

シリコーン樹脂微粉末 ０．１部 （トーレシリコーン社製：トレフィルＲ−９２５）
塩化メチレン ９０部
参考例４
直径３０ｍｍのアルミ円筒状支持体上に、下記組成の中間層用塗工液、電荷発生層用塗工液、電荷輸送層用塗工液、保護層用塗工液を順次、塗布・乾燥して約０．５μｍ厚の中間層、約０．３μｍ厚の電荷発生層、約２０μｍ厚の電荷輸送層、約３μｍ厚の保護層を形成して、本発明の電子写真感光体を作製した。

Silicone resin fine powder 0.1 part (Toray Silicone Co., Ltd .: Trefil R-925)
90 parts of methylene chloride
Reference example 4
On an aluminum cylindrical support having a diameter of 30 mm, an intermediate layer coating solution, a charge generation layer coating solution, a charge transport layer coating solution, and a protective layer coating solution having the following composition were sequentially applied and dried. Then, an intermediate layer having a thickness of about 0.5 μm, a charge generating layer having a thickness of about 0.3 μm, a charge transporting layer having a thickness of about 20 μm, and a protective layer having a thickness of about 3 μm were formed to produce the electrophotographic photosensitive member of the present invention.

(Intermediate layer coating solution)
Polyamide resin (Toray Industries, Inc .: CM-8000) 30 parts Methanol 700 parts 1-Butanol 300 parts (Coating liquid for charge generation layer)
5 parts of charge generating material with the following structure

ポリビニルブチラール（ＵＣＣ社製：ＸＹＨＬ） ２部
シクロヘキサノン ２００部
テトラヒドロフラン ２００部
（電荷輸送層用塗工液）
ポリアリレート樹脂 １０部
下記構造の電荷輸送物質 ７部

Polyvinyl butyral (UCC: XYHL) 2 parts Cyclohexanone 200 parts Tetrahydrofuran 200 parts (Coating liquid for charge transport layer)
Polyarylate resin 10 parts Charge transport material with the following structure 7 parts

塩化メチレン ９０部
（保護層用塗工液）
ビスフェノールＣ型ポリカーボネート １０部
酸化スズ ５部
メチルフェニルシリコーンオイル ０．１部 （信越シリコーン社製：ＫＦ５６）
塩化メチレン ９０部
比較例１
実施例１における電荷輸送層用塗工液中のシリコーンオイルを除いた以外は、実施例１と全く同様にして電子写真感光体を作製した。

90 parts of methylene chloride (coating liquid for protective layer)
0.1 parts of bis phenol C type polycarbonate 10 parts of tin oxide 5 parts of methyl phenyl silicone oil (Shin-Etsu Silicone Co., Ltd.: KF56)
90 parts of methylene chloride Comparative Example 1
An electrophotographic photosensitive member was produced in exactly the same manner as in Example 1 except that the silicone oil in the charge transport layer coating solution in Example 1 was omitted.

Comparative Example 2
An electrophotographic photosensitive member was produced in the same manner as in Example 1 except that the charge transport layer coating solution in Example 1 was changed to the following.

(Coating liquid for charge transport layer)
Polyarylate resin 10 parts Charge transport material with the following structure 7 parts

アンチモンドープ酸化スズ（三菱金属社製：Ｔ−１） ０．１部
塩化メチレン ９０部
比較例３
実施例１における電荷輸送層用塗工液を下記のものに代えた以外は、実施例１と全く同様にして電子写真感光体を作製した。
（電荷輸送層用塗工液）
ポリアリレート樹脂 １０部
下記構造の電荷輸送物質 ７部

Antimony-doped tin oxide (Mitsubishi Metals Corporation: T-1) 0.1 part Methylene chloride 90 parts Comparative Example 3
An electrophotographic photosensitive member was produced in exactly the same manner as in Example 1 except that the charge transport layer coating solution in Example 1 was replaced with the following.
(Coating liquid for charge transport layer)
Polyarylate resin 10 parts Charge transport material with the following structure 7 parts

メチルフェニルポリシロキサン ０．００５部 （信越シリコーン社製：ＫＦ５６）
塩化メチレン ９０部
比較例４
実施例１における電荷輸送層用塗工液中のシリコーンオイルを除いた以外は、実施例１と全く同様にして電子写真感光体を作製した。

0.005 part of methylphenylpolysiloxane (Shin-Etsu Silicone Co., Ltd .: KF56)
90 parts of methylene chloride Comparative Example 4
An electrophotographic photosensitive member was produced in exactly the same manner as in Example 1 except that the silicone oil in the charge transport layer coating solution in Example 1 was omitted.

The electrophotographic photoreceptors of Example 1 , Reference Examples 2 to 4 and Comparative Examples 1 to 4 prepared as described above are mounted on the electrophotographic process cartridge shown in FIG. Then, 10,000 sheets were printed continuously, and the black spot images at that time were evaluated. Further, the cross section of the charge transport layer or the protective layer of the electrophotographic photosensitive member of Example 1 , Reference Examples 2 to 4 and Comparative Examples 1 to 4 is observed with a scanning electron microscope, and the size of dispersed particles is obtained. It was. The above results are shown together in Table 1.

FIG. 3 is a view showing a layer structure of an electrophotographic photosensitive member used in the electrophotographic image forming apparatus of the present invention. FIG. 4 is a diagram showing another layer configuration of an electrophotographic photosensitive member used in the electrophotographic image forming apparatus of the present invention. FIG. 6 is a view showing still another layer configuration of an electrophotographic photosensitive member used in the electrophotographic image forming apparatus of the present invention. FIG. 6 is a view showing still another layer configuration of an electrophotographic photosensitive member used in the electrophotographic image forming apparatus of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS Schematic for demonstrating the electrophotographic method and electrophotographic apparatus of this invention. FIG. 1 is a schematic view for explaining a process cartridge for an electrophotographic apparatus, which is representative of the present invention.

Claims (3)

In an electrophotographic method in which an electrophotographic photosensitive member is charged and subjected to exposure, development, and transfer to form an image, the photosensitive member contains particles having a volume resistance of 1 × 10 ¹² Ωcm or more and a diameter of 0.1 μm or more and 5.0 μm or less. An electrophotographic method comprising an outermost layer dispersed and contained in a polyarylate resin, wherein the dispersed and contained particles are dispersed silicone oil, and the charging is a contact charging method. In an electrophotographic apparatus provided with an electrophotographic photosensitive member and a charging unit, an exposing unit, a developing unit, and a transferring unit, the photosensitive unit is made of a polymer having a volume resistance of 1 × 10 ¹² Ωcm or more and a diameter of 0.1 μm to 5.0 μm. An electrophotographic apparatus comprising an outermost layer dispersed and contained in an arylate resin, wherein the dispersed and contained particles are dispersed silicone oil, and the charging is a contact charging method. A process cartridge for an electrophotographic apparatus comprising at least an electrophotographic photosensitive member and adopting a contact charging method, wherein the photosensitive member is a polymer containing particles having a volume resistance of 1 × 10 ¹² Ωcm or more and a diameter of 0.1 μm or more and 5.0 μm or less. electrophotographic apparatus for the process cartridge, wherein the dispersion contains particles with that having a top surface which is dispersed and contained in the polyarylate resin is a silicone oil dispersed state.

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