JP2005037836A - Electrophotographic photoreceptor, electrophotographic apparatus, and process cartridge - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrophotographic photoreceptor capable of achieving both of electrophotographic characteristics and durability, and provide an electrophotographic apparatus and a process cartridge using the photoreceptor. <P>SOLUTION: The electrophotographic photoreceptor 1 formed with a photosensitive layer 3 on a substrate 2 is provided with a surface layer 6 containing fluorine-based resin particles of ≥0.95 in mean sphericity and a fluorine-based graft polymer on the side furthest from the substrate 2 of the photosensitive layer 3. The content of the fluorine-based resin particles is specified to 3 to 15wt% of the total weight of the solid content of the surface layer 6 and the content of the fluorine-based graft polymer is specified to 1 to 5wt% of the weight of the fluorine-based resin particles. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an electrophotographic photosensitive member, an electrophotographic apparatus, and a process cartridge used for electrophotographic image formation.

  Electrophotographic image formation has the advantages of high speed and high print quality, and is therefore widely used in fields such as copying machines and laser beam printers. As an electrophotographic photosensitive member used in an electrophotographic apparatus (hereinafter, simply referred to as “photosensitive member”), a conventional inorganic photoconductive material such as selenium, selenium-tellurium alloy, selenium-arsenic alloy, cadmium sulfide is used. Compared to photoreceptors, electrophotographic photoreceptors using organic photoconductive materials, which are inexpensive and have advantages in terms of manufacturability and disposal, have come to dominate. Among them, the functionally separated type organic photoreceptor in which a charge generation layer that generates charges upon exposure and a charge transport layer that transports charges is laminated is excellent in terms of electrophotographic characteristics, and various proposals have been made. It has been put into practical use.

  By the way, the organic photoreceptor is generally inferior in mechanical strength as compared with the inorganic photoreceptor, and is liable to be rubbed and worn by a mechanical external force such as a cleaning blade, a developing brush, and paper, and has a short life. Further, in a system using a contact charging method that has been used in recent years from the viewpoint of ecology, the wear of the photoreceptor may be significantly increased as compared with a non-contact charging method using corotron. Thus, if the durability of the photoreceptor is insufficient, it may cause a decrease in image density due to a reduction in sensitivity, a generation of fog on an image due to a decrease in charging potential, and the like.

Therefore, in order to avoid such a phenomenon, a method for improving the durability of the photosensitive layer has been studied. For example, the surface energy of the surface layer of the photoreceptor is reduced by dispersing the fluorine resin particles in the surface layer. A method has been proposed (see, for example, Patent Document 1).
JP-A-63-221355

  However, even in the case of a photoreceptor to which the above conventional method is applied, general fluororesin particles have low dispersibility and high cohesion, so that the fluororesin particles present in the surface layer are not present. It tends to be uniform and it is difficult to obtain a sufficient durability improvement effect. Therefore, it is not always easy to enhance durability without impairing the originally required electrophotographic characteristics.

  Incidentally, by adding a fluorine-based graft polymer as a dispersion aid, it is possible to achieve some improvement in the dispersibility and cohesiveness of the fluorine-based resin particles. However, in order to obtain a sufficient improvement effect, it is necessary to increase the addition amount of the fluorine-based graft polymer, and as a result, the residual potential of the resulting photoreceptor is likely to increase due to repeated use over a long period of time, and electrophotographic characteristics Will be damaged.

  The present invention has been made in view of the above-described problems of the prior art. An electrophotographic photoreceptor capable of achieving both electrophotographic characteristics and durability at a high level, and an electrophotographic apparatus using the photoreceptor. And it aims at providing a process cartridge.

  In order to achieve the above object, the present inventors first studied a surface layer containing fluorine resin particles and a fluorine graft polymer, and as a result, the phenomenon in which the concentration decreases due to an increase in residual potential is As a result, it was found that the fluorine-based graft polymer used as a dispersion aid for dispersing the polymer was present in the bulk in a free state. More specifically, the addition amount of the fluorine-based graft polymer often exceeds the required amount, and the surplus fluorine-based graft polymer that has not been adsorbed exists in the surface layer bulk in a free state. Since the free fluorine-based graft polymer becomes a causative substance that develops trap sites that accumulate electric charges, the concentration tends to decrease due to an increase in residual potential during repeated use under high temperature and high humidity. That is, even if the physical durability can be improved, stable electrophotographic characteristics cannot be obtained.

  On the other hand, various product grades are provided for commercially available fluororesin particles, and are classified mainly by characteristic values such as particle size and particle size distribution. However, even with fluororesin particles having the same particle size and particle size distribution grade, the adsorption efficiency of the fluorograft polymer used as a dispersion aid varies from lot to lot, and the photoreceptor characteristics often vary. In particular, when fluorinated resin particles that are difficult to adsorb the fluorinated graft polymer are used, it is necessary to add a large amount of fluorinated graft polymer in order to uniformly disperse the fluorinated resin particles in the surface layer. The surplus fluorine-based graft polymer that has not existed is present in the surface layer bulk in a free state. Therefore, in this case as well, as described above, even if the physical durability can be improved, stable electrophotographic characteristics cannot be obtained.

    Therefore, the present inventors examined a method for efficiently adsorbing the fluorine-based graft polymer to the fluorine-based resin particles. Specifically, a lot of commercially available fluororesin particles with the same particle size and particle size distribution grade are prepared, the adsorption efficiency of the fluorine-based graft polymer under the same conditions, physical durability as a photoreceptor, electrical Stability was compared. At the same time, the physical and chemical characteristics of the fluororesin particles used were compared and examined. As a result, the average sphericity of the fluororesin particles greatly affects the adsorption efficiency of the fluorograft polymer, and the superiority or inferiority of the adsorption efficiency greatly contributes to physical durability and electrical stability as a photoconductor. I found out.

  For example, if the average sphericity of the fluorinated resin particles is greater than a certain level, that is, if the particle shape is close to a true sphere, the adsorption efficiency of the fluorinated graft polymer will be good. It becomes possible to disperse uniformly. That is, the durability against abrasion and scratches is improved, and the releasability with respect to the toner is improved, so that it is possible to produce a photoconductor having a sufficient cleaning effect. However, while it becomes possible to disperse the fluororesin uniformly with only a small amount of the fluorine-based graft polymer, the surplus fluorine-based graft polymer that has not been adsorbed exists in the surface layer bulk in a free state. As a result, trap sites for accumulating charges are induced, and the residual potential increases due to repeated use under high temperature and high humidity, resulting in a photoconductor that tends to cause a decrease in density. Therefore, when using fluorine-based resin particles having an average sphericity larger than a certain level, it is necessary to add a necessary amount of a fluorine-based graft polymer, which is a dispersion aid, and adjust so that no excess is generated. .

  Conversely, if the average sphericity of the fluororesin particles is smaller than a certain level, that is, if the particle shape shifts from a true sphere to an irregular shape, the adsorption efficiency of the fluorograft polymer deteriorates and a large amount of fluorograft polymer is added. Otherwise, the fluororesin particles cannot be uniformly dispersed in the surface layer. That is, if it is intended to uniformly disperse the fluorine-based resin particles in the surface layer, it is necessary to add a large amount of the fluorine-based graft polymer, which leads to an increase in excess fluorine-based graft polymer that is not adsorbed. The fluorine-based graft polymer present in the bulk with the excess fluorine-based graft polymer released induces trap sites that accumulate charges, and the residual potential increases due to repeated use under high temperature and high humidity, resulting in a decrease in concentration. The cause is as described above. Therefore, in order to obtain electrophotographic characteristics using fluororesin particles having an average sphericity smaller than a certain level, it is necessary to moderately reduce the addition amount of the fluorograft polymer. The particles cannot be uniformly dispersed in the surface layer, and it becomes impossible to produce a photoreceptor having physical durability.

  And based on the above examination results, the present inventors use a specific amount of fluorine-based resin particles having a specific average sphericity, and further use a specific amount of fluorine-based graft polymer for the surface of the fluorine-based resin particles. By forming the layer, the adsorption efficiency of the fluorine-based graft polymer to the fluorine-based resin particles can be improved, and the durability of the surface layer and the releasability to the toner can be sufficiently enhanced without impairing the electrophotographic characteristics. The inventors have found that this is possible and have completed the present invention.

  That is, the electrophotographic photoreceptor of the present invention is an electrophotographic photoreceptor comprising a conductive substrate and a photosensitive layer formed on the substrate, and the photosensitive layer has an average spherical shape on the side farthest from the substrate. A surface layer containing fluorine resin particles having a degree of 0.95 or more and a fluorine-based graft polymer, and the content of the fluorine resin particles is 3 to 15% by weight based on the total solid content of the surface layer And content of a fluorine-type graft polymer is 1 to 5 weight% with respect to the weight of a fluorine-type resin particle, It is characterized by the above-mentioned.

  In the electrophotographic photoreceptor of the present invention, the surface layer contains a specific amount of fluorine resin particles having an average sphericity of 0.95 or more and a fluorine graft polymer, whereby the electrophotographic characteristics of the photoreceptor can be improved. Sufficient durability to the surface layer without damage, and sufficient releasability to the toner are imparted at a high level, so that the electrophotographic characteristics are maintained at a high level and the abrasion and wear are sufficiently suppressed. Can do. Therefore, even when the electrophotographic photosensitive member of the present invention is used repeatedly for a long period of time, the image density is reduced by reducing the friction sensitivity, the fogging of the image is caused by the reduction of the charging potential, and the residual potential is increased. It becomes possible to suppress.

The “average sphericity” as used in the present invention is an analysis of the particle shape based on the projected image of the particle, and the ratio of the projected area and the area of a circle having the same circumference as the projected circumference of the particle is used as follows: It can be measured by the procedure. First, using a scanning electron microscope and an image analyzer, image analysis of the SEM photograph obtained with the electron microscope is performed, and the projected area (A) and the perimeter (PM) of the particles are measured. Yeah. The number of measured particles is 100 or more. When the area of a perfect circle corresponding to the perimeter (PM) is (B), the roundness of the particle is A / B. Therefore, assuming a perfect circle having the same circumference as the sample particle (PM), PM = 2πr and B = πr ² , so that B = π × (PM / 2π) ² , and each particle Is calculated as A / B = A × 4π / (PM) ² . The roundness of 100 or more particles thus obtained is determined, and the average value is defined as the average sphericity.

  The electrophotographic apparatus of the present invention includes an electrophotographic photosensitive member of the present invention, a charging device that charges the photosensitive member, an exposure device that exposes the charged photosensitive member to form an electrostatic latent image, and an electrostatic device. The image forming apparatus includes: a developing device that develops the latent image to form a toner image; and a transfer device that transfers the toner image from the photosensitive member to a transfer medium.

  The process cartridge of the present invention also forms a toner image by developing the electrophotographic photosensitive member of the present invention, a charging device for charging the photosensitive member, and developing an electrostatic latent image formed by exposing the charged photosensitive member. And at least one selected from a developing device and a cleaning device that removes residual toner from the photoconductor after transfer.

  In the electrophotographic apparatus and process cartridge of the present invention, it is possible to obtain good image quality over a long period of time by using the electrophotographic photosensitive member of the present invention in which electrophotographic characteristics and durability are compatible at a high level. Become.

  According to the electrophotographic photosensitive member of the present invention, it is possible to sufficiently suppress abrasion and abrasion while maintaining the electrophotographic characteristics at a high level. In addition, according to the electrophotographic apparatus and the process cartridge of the present invention, even when the electrophotographic photosensitive member of the present invention is used repeatedly for a long period of time, the image density is lowered by reducing the friction sensitivity, and the image by lowering the charging potential. It is possible to suppress the occurrence of fog and further increase in residual potential.

  Hereinafter, preferred embodiments of the present invention will be described in detail. In the drawings, the same or corresponding parts are denoted by the same reference numerals, and redundant description is omitted.

  FIG. 1 is a schematic sectional view showing a preferred embodiment of the electrophotographic photosensitive member of the present invention. The electrophotographic photosensitive member 1 shown in FIG. 1 includes a function-separated type photosensitive layer 3 in which a charge generation layer 5 and a charge transport layer 6 are separately provided. The charge generation layer 5 and the charge transport layer 6 are stacked in this order. Here, the charge transport layer 6 is a surface layer (a layer disposed on the side farthest from the substrate 2) in the photoreceptor 1, and will be described later in detail, but fluorine resin particles having an average sphericity of 0.95 or more; A specific amount of each of the fluorine-based graft polymers is contained.

  Hereinafter, each element of the photoreceptor 1 will be described.

  Any conductive substrate 2 may be used as long as it is conventionally used. For example, metals such as aluminum, nickel, chromium, stainless steel, and plastic films provided with thin films such as aluminum, titanium, nickel, chromium, stainless steel, gold, vanadium, tin oxide, indium oxide, ITO, etc. Examples thereof include paper coated with or impregnated with a property-imparting agent, and a plastic film. The shape of the substrate 2 is not limited to a drum shape, and may be a sheet shape or a plate shape.

  When a metal pipe is used as the conductive substrate 2, the surface may remain as it is, or a process such as mirror cutting, etching, anodizing, rough cutting, centerless grinding, sand blasting, wet honing, etc. is performed in advance. May be.

  The undercoat layer 4 is provided as necessary for the purpose of preventing light reflection on the surface of the substrate 2 and preventing inflow of unnecessary carriers from the substrate 2 to the photosensitive layer 3. Materials for the undercoat layer 3 include metal powders such as aluminum, copper, nickel, and silver, conductive metal oxides such as antimony oxide, indium oxide, tin oxide, and zinc oxide, carbon fiber, carbon black, and graphite. Examples thereof include a conductive material such as powder dispersed in a binder resin and coated on a support. Moreover, 2 or more types of metal oxide fine particles can be mixed and used. Further, the powder resistance may be controlled by performing a surface treatment with a coupling agent on the metal oxide fine particles.

  The binder resin contained in the undercoat layer 4 includes acetal resins such as polyvinyl butyral, polyvinyl alcohol resin, casein, polyamide resin, cellulose resin, gelatin, polyurethane resin, polyester resin, methacrylic resin, acrylic resin, and polyvinyl chloride resin. , Polyvinyl acetate resins, vinyl chloride-vinyl acetate-maleic anhydride resins, silicone resins, silicone-alkyd resins, phenolic resins, phenol-formaldehyde resins, melamine resins, urethane resins, and other known polymer resin compounds, and charge transport properties A charge transporting resin having a group or a conductive resin such as polyaniline can be used. Among them, resins insoluble in the upper layer coating solvent are preferably used, and phenol resins, phenol-formaldehyde resins, melamine resins, urethane resins, epoxy resins, and the like are particularly preferably used.

  The ratio between the metal oxide fine particles and the binder resin in the undercoat layer 4 is not particularly limited, and can be arbitrarily set within a range in which desired electrophotographic photoreceptor characteristics can be obtained.

  When the undercoat layer 4 is formed, a coating solution in which the above components are added to a predetermined solvent is used. Examples of such solvents include aromatic hydrocarbon solvents such as toluene and chlorobenzene, aliphatic alcohol solvents such as methanol, ethanol, n-propanol, iso-propanol, and n-butanol, acetone, cyclohexanone, and 2-butanone. Ketone solvents, halogenated aliphatic hydrocarbon solvents such as methylene chloride, chloroform, ethylene chloride, cyclic or linear ether solvents such as tetrahydrofuran, dioxane, ethylene glycol, diethyl ether, methyl acetate, ethyl acetate, n acetate -Organic solvents, such as ester solvents, such as butyl. These solvents can be used alone or in combination of two or more. When mixing, any solvent can be used as long as the binder resin can be dissolved as a mixed solvent.

  In addition, as a method for dispersing the metal oxide fine particles in the coating solution for forming the undercoat layer, a media disperser such as a ball mill, a vibration ball mill, an attritor, a sand mill, a horizontal sand mill, an agitator, an ultrasonic disperser, a roll mill, Medialess dispersers such as high-pressure homogenizers can be used. Further, examples of the high-pressure homogenizer include a collision method in which the dispersion liquid is dispersed by liquid-liquid collision or liquid-wall collision in a high pressure state, and a penetration method in which the fine liquid is penetrated and dispersed in a high pressure state.

  The undercoat layer forming coating solution thus obtained can be applied to the substrate 1 by dip coating, push-up coating, wire bar coating, spray coating, blade coating, knife coating, curtains. Examples thereof include a coating method. The thickness of the undercoat layer 4 is preferably 15 μm or more, and more preferably 20 to 50 μm.

  Resin particles may be added to the undercoat layer 4 in order to adjust the surface roughness. As the resin particles, silicone resin particles, cross-linked PMMA resin particles, and the like can be used.

  Further, the surface of the undercoat layer 4 can be polished for adjusting the surface roughness. As a polishing method, buffing, sand blasting, wet honing, grinding, or the like can be used.

  Although not shown, an intermediate layer may be further provided on the undercoat layer 4 in order to improve electrical characteristics, improve image quality, improve image quality maintenance, and improve photosensitive layer adhesion. As the binder resin used for the intermediate layer, acetal resins such as polyvinyl butyral, polyvinyl alcohol resin, casein, polyamide resin, cellulose resin, gelatin, polyurethane resin, polyester resin, methacrylic resin, acrylic resin, polyvinyl chloride resin, polyvinyl In addition to polymer resins such as acetate resin, vinyl chloride-vinyl acetate-maleic anhydride resin, silicone resin, silicone-alkyd resin, phenol-formaldehyde resin, melamine resin, zirconium, titanium, aluminum, manganese, silicon atom, etc. And organometallic compounds containing These compounds can be used alone or as a mixture or polycondensate of a plurality of compounds. Among these, organometallic compounds containing zirconium or silicon are excellent in performance, such as low residual potential, little potential change due to environment, and little potential change due to repeated use.

  As the solvent used for forming the intermediate layer, known organic solvents, for example, aromatic hydrocarbon solvents such as toluene and chlorobenzene, aliphatics such as methanol, ethanol, n-propanol, iso-propanol, and n-butanol Alcohol solvents, ketone solvents such as acetone, cyclohexanone and 2-butanone, halogenated aliphatic hydrocarbon solvents such as methylene chloride, chloroform and ethylene chloride, cyclic or linear such as tetrahydrofuran, dioxane, ethylene glycol and diethyl ether Ether solvents, ester solvents such as methyl acetate, ethyl acetate, and n-butyl acetate, and these solvents can be used alone or in admixture of two or more. When mixing, any solvent can be used as long as it can dissolve the binder resin as a mixed solvent.

  As the coating method for forming the intermediate layer, conventional methods such as dip coating, push-up coating, wire bar coating, spray coating, blade coating, knife coating, and curtain coating can be used.

  In addition to improving the coatability of the upper layer, the intermediate layer also serves as an electrical blocking layer. However, when the film thickness is too large, the electrical barrier becomes too strong, causing desensitization and potential increase due to repetition. . Therefore, when the intermediate layer is formed, the film thickness is set to 0.1 to 3 μm.

  Further, the intermediate layer in this case may be used as the undercoat layer 4.

  The charge generation layer 5 is formed by dispersing a charge generation material in an appropriate binder resin. As such a charge generation material, phthalocyanine pigments such as metal-free phthalocyanine, chlorogallium phthalocyanine, hydroxygallium phthalocyanine, dichlorotin phthalocyanine, and titanyl phthalocyanine can be used. ), A chlorogallium phthalocyanine crystal having strong diffraction peaks at 7.4 °, 16.6 °, 25.5 ° and 28.3 ° at a Bragg angle (2θ ± 0.2 °) with respect to CuKα characteristic X-rays. Metal-free phthalocyanine crystals having strong diffraction peaks at 7.7 °, 9.3 °, 16.9 °, 17.5 °, 22.4 ° and 28.8 °, Bragg angle (2θ for CuKα characteristic X-ray) ± 0.2 °) at least 7.5 °, 9.9 °, 12.5 °, 16.3 °, 18 Hydroxygallium phthalocyanine crystals having strong diffraction peaks at 6 °, 25.1 ° and 28.3 °, at least 9.6 °, 24.1 ° and Bragg angle (2θ ± 0.2 °) with respect to CuKα characteristic X-ray A titanyl phthalocyanine crystal having a strong diffraction peak at 27.2 ° can be used. In addition, as the charge generation material, a quinone pigment, a perylene pigment, an indigo pigment, a bisbenzimidazole pigment, an anthrone pigment, a quinacridone pigment, and the like can be used. These charge generation materials can be used alone or in admixture of two or more.

  Examples of the binder resin in the charge generation layer include polycarbonate resin such as bisphenol A type or bisphenol Z type, acrylic resin, methacrylic resin, polyarylate resin, polyester resin, polyvinyl chloride resin, polystyrene resin, acrylonitrile-styrene copolymer Combined resin, acrylonitrile-butadiene copolymer, polyvinyl acetate resin, polyvinyl formal resin, polysulfone resin, styrene-butadiene copolymer resin, vinylidene chloride-acrylonitrile copolymer resin, vinyl chloride-vinyl acetate-maleic anhydride resin, Silicone resin, phenol-formaldehyde resin, polyacrylamide resin, polyamide resin, poly-N-vinylcarbazole resin, or the like can be used. These binder resins can be used alone or in combination of two or more. The mixing ratio of the charge generating material and the binder resin is preferably in the range of 10: 1 to 1:10.

  When the charge generation layer 5 is formed, a coating solution in which the above components are added to a predetermined solvent is used. Examples of such solvents include aromatic hydrocarbon solvents such as toluene and chlorobenzene, aliphatic alcohol solvents such as methanol, ethanol, n-propanol, iso-propanol, and n-butanol, acetone, cyclohexanone, and 2-butanone. Ketone solvents, halogenated aliphatic hydrocarbon solvents such as methylene chloride, chloroform, ethylene chloride, cyclic or linear ether solvents such as tetrahydrofuran, dioxane, ethylene glycol, diethyl ether, methyl acetate, ethyl acetate, n acetate -Organic solvents, such as ester solvents, such as butyl. These solvents can be used alone or in combination of two or more. When mixing, any solvent can be used as long as the binder resin can be dissolved as a mixed solvent.

  In order to disperse the charge generation material in the resin, the coating liquid is subjected to a dispersion treatment. As a dispersion method, a media disperser such as a ball mill, a vibration ball mill, an attritor, a sand mill, or a horizontal sand mill, or a medialess disperser such as an agitator, an ultrasonic disperser, a roll mill, or a high-pressure homogenizer can be used. Further, examples of the high-pressure homogenizer include a collision method in which the dispersion liquid is dispersed by liquid-liquid collision or liquid-wall collision in a high pressure state, and a penetration method in which the fine liquid is penetrated and dispersed in a high pressure state.

  Examples of methods for applying the coating solution thus obtained onto the undercoat layer 4 include dip coating, push-up coating, wire bar coating, spray coating, blade coating, knife coating, curtain coating, and the like. Is mentioned. The film thickness of the charge generation layer 5 is preferably set in the range of 0.01 to 5 μm, more preferably 0.05 to 2.0 μm.

  As described above, the charge transport layer 6 is a layer containing fluorine-based resin particles having an average sphericity of 0.95 or more and a fluorine-based graft polymer. Further, the content of the fluorine-based resin particles with respect to the total solid content of the charge transport layer 6 is 3 to 15% by weight, and the content of the fluorine-based graft polymer with respect to the weight of the fluorine-based resin particles is 1 to 3% by weight.

  In addition, when the content of the fluorine-based resin particles with respect to the total solid content of the charge transport layer 6 is less than 3% by weight, the charge transport layer 6 is not sufficiently modified by the dispersion of the fluorine-based resin particles. On the other hand, when the content exceeds 15% by weight, a decrease in light transmittance and a decrease in film strength are likely to occur.

  Moreover, when the addition amount of the fluorine-type graft polymer with respect to the weight of fluorine-type resin particles is less than 1 weight%, the dispersibility improvement effect of a fluorine-type resin particle becomes inadequate. When the content exceeds 5% by weight, the amount of the fluorine-based graft polymer added to the fluorine-based resin particles having an average sphericity of 0.95 or more exceeds the required amount, and an excess fluorine-based graft polymer that has not been adsorbed It exists in the bulk of the charge transport layer 6 in a free state, and expresses trap sites that accumulate charges. As a result, the residual potential increases due to repeated use under high temperature and high humidity, and the photoconductor is likely to cause a decrease in density.

  When the average sphericity of the fluororesin particles is less than 0.95, the fluororesin particles are not contained in the charge transport layer 6 even if 5 wt% of the fluorograft polymer is added to the weight of the fluororesin particles. Thus, a photoconductor having sufficient physical durability cannot be obtained in that the durability against abrasion and scratches and the release (cleaning property) against toner are reduced.

  In addition, the fluorine-based resin particles having an average sphericity of less than 0.95 are uniformly dispersed in the charge transport layer 6 by increasing the addition amount of the fluorine-based graft polymer with respect to the weight of the fluorine-based resin particles more than 5% by weight. However, in this case, although the physical durability is excellent, stable electrophotographic characteristics cannot be obtained.

  In order to obtain fluororesin particles having an average sphericity of 0.95 or more used in the present invention, the production conditions may be controlled in the fluororesin particle production process. If not matched, a lot having a desired average sphericity may be obtained by selecting a lot.

  Examples of the fluororesin particles used in the present invention include a tetrafluoroethylene resin, a trifluorinated ethylene resin, a hexafluoropropylene resin, a vinyl fluoride resin, a vinylidene fluoride resin, a difluorodiethylene chloride resin, and their It is desirable to appropriately select one or two or more types from among the copolymers, but tetrafluoroethylene resin and vinylidene fluoride resin are particularly preferable.

  The primary particle size of the fluororesin particles is preferably 0.05 to 1 μm, more preferably 0.1 to 0.5 μm. When the primary particle size is less than 0.05 μm, aggregation during dispersion tends to proceed. On the other hand, if it exceeds 1 μm, image quality defects are likely to occur.

  The fluorine-based graft polymer is preferably a resin graft-polymerized from a macromonomer composed of an acrylic ester compound, a methacrylic ester compound, a styrene compound, or the like and perfluoroalkylethyl methacrylate.

  The charge transport layer 6 includes, in addition to the above components, a charge generation material for expressing an original function as a charge transport layer, and further a binder resin. Examples of such charge transport materials include oxadiazole derivatives such as 2,5-bis (p-diethylaminophenyl) -1,3,4-oxadiazole, 1,3,5-triphenyl-pyrazoline, 1- [Pyridyl- (2)]-3- (p-diethylaminostyryl) -5- (p-diethylaminostyryl) pyrazoline and other pyrazoline derivatives, triphenylamine, N, N′-bis (3,4-dimethylphenyl) biphenyl Aromatic tertiary amino compounds such as -4-amine, tri (p-methylphenyl) aminyl-4-amine, dibenzylaniline, N, N'-bis (3-methylphenyl) -N, N'-diphenyl Aromatic tertiary diamino compounds such as benzidine, 3- (4′-dimethylaminophenyl) -5,6-di- (4′-methoxyphenyl) -1, 1,2,4-triazine derivatives such as 1,4-triazine, hydrazone derivatives such as 4-diethylaminobenzaldehyde-1,1-diphenylhydrazone, quinazoline derivatives such as 2-phenyl-4-styryl-quinazoline, 6-hydroxy-2 Benzofuran derivatives such as 1,3-di (p-methoxyphenyl) benzofuran, α-stilbene derivatives such as p- (2,2-diphenylvinyl) -N, N-diphenylaniline, enamine derivatives, carbazole such as N-ethylcarbazole Derivatives, hole transport materials such as poly-N-vinylcarbazole and its derivatives, quinone compounds such as chloranil and broanthraquinone, tetraanoquinodimethane compounds, 2,4,7-trinitrofluorenone, 2,4, Full such as 5,7-tetranitro-9-fluorenone Examples thereof include an electron transport material such as an oleone compound, a xanthone compound, and a thiophene compound, and a polymer having a group composed of the above-described compound in a main chain or a side chain. These charge transport materials can be used alone or in combination of two or more.

  Examples of the binder resin in the charge transport layer 6 include polycarbonate resin such as bisphenol A type or bisphenol Z type, acrylic resin, methacrylic resin, polyarylate resin, polyester resin, polyvinyl chloride resin, polystyrene resin, acrylonitrile- Styrene copolymer resin, acrylonitrile-butadiene copolymer resin, polyvinyl acetate resin, polyvinyl formal resin, polysulfone resin, styrene-butadiene copolymer resin, vinylidene chloride-acrylonitrile copolymer resin, vinyl chloride-vinyl acetate-anhydrous Insulating resins such as maleic acid resin, silicone resin, phenol-formaldehyde resin, polyacrylamide resin, polyamide resin, chlorine rubber, and polyvinylcarbazole, polyvinyl Anthracene, organic photoconductive polymers such as polyvinyl pyrene, and the like. These binder resins can be used alone or in combination of two or more.

  The charge transport layer 6 is formed using a coating solution in which the above components are added to a predetermined solvent. Solvents used for forming the charge transport layer include known organic solvents, for example, aromatic hydrocarbon solvents such as toluene and chlorobenzene, and fats such as methanol, ethanol, n-propanol, iso-propanol, and n-butanol. Aromatic alcohol solvents, ketone solvents such as acetone, cyclohexanone and 2-butanone, halogenated aliphatic hydrocarbon solvents such as methylene chloride, chloroform and ethylene chloride, cyclic or straight chain such as tetrahydrofuran, dioxane, ethylene glycol and diethyl ether Ether solvents, ester solvents such as methyl acetate, ethyl acetate, and n-butyl acetate, and these solvents can be used alone or in admixture of two or more. When mixing, any solvent can be used as long as the binder resin can be dissolved as a mixed solvent. The blending ratio of the charge transport material and the binder resin is preferably 10: 1 to 1: 5.

  Examples of the dispersion method of the coating liquid for dispersing the fluorine resin particles in the charge transport layer 6 include a media disperser such as a ball mill, a vibrating ball mill, an attritor, a sand mill, a horizontal sand mill, a stirring, an ultrasonic disperser, and a roll mill. Medialess dispersers such as high-pressure homogenizers can be used. Further, examples of the high-pressure homogenizer include a collision method in which the dispersion liquid is dispersed by liquid-liquid collision or liquid-wall collision in a high pressure state, and a penetration method in which the fine liquid is penetrated and dispersed in a high pressure state.

  The charge transport layer layer forming coating solution thus obtained can be applied onto the charge generation layer 5 by dip coating, push-up coating, wire bar coating, spray coating, blade coating, knife coating. Ordinary methods such as a coating method and a curtain coating method can be used. The film thickness of the charge transport layer is preferably set in the range of 5 to 50 μm, more preferably 10 to 40 μm.

  For the purpose of preventing deterioration of the photoreceptor due to ozone, nitrogen oxide, light, or heat generated in the electrophotographic apparatus, an antioxidant, a light stabilizer, a heat stabilizer, etc. are included in each layer constituting the photosensitive layer 3. Additives can be added. For example, examples of the antioxidant include hindered phenol, hindered amine, paraphenylenediamine, arylalkane, hydroquinone, spirochroman, spiroidanone and derivatives thereof, organic sulfur compounds, and organic phosphorus compounds. Examples of light stabilizers include derivatives such as benzophenone, benzoazole, dithiocarbamate, and tetramethylpipen.

  For the purpose of improving the smoothness of the surface, a leveling agent such as silicone oil can be added to the surface layer.

  Further, as shown in FIG. 2, a protective layer 7 may be further provided on the charge transport layer 6 so as to be a surface layer of the photoreceptor 1. In this case, the protective layer 7 contains fluorine-based resin particles having an average sphericity of 0.95 or more and a fluorine-based graft polymer, and the content of the fluorine-based resin particles is 3 with respect to the total solid content of the protective layer 7. It is necessary that the content of the fluorine-based graft polymer is 1 to 5% by weight with respect to the weight of the fluorine-based resin particles.

  The protective layer 7 may further contain a conductive material and a binder resin in addition to the fluorine resin particles and the fluorine graft polymer according to the present invention. Examples of the conductive material include metallocene compounds such as N, N′-dimethylferrocene, N, N′-diphenyl-N, N′-bis (3-methylphenyl)-[1,1′-biphenyl] -4,4. '-Aromatic amine compounds such as diamine, molybdenum oxide, tungsten oxide, antimony oxide, tin oxide, titanium oxide, indium oxide, solid solution carrier of tin oxide and antimony or antimony oxide, or a mixture thereof, or in a single particle However, the present invention is not limited to these.

  The binder resin used for the protective layer 7 includes polyamide resin, polyvinyl acetal resin, polyurethane resin, polyester resin, epoxy resin, polyketone resin, polycarbonate resin, polyvinyl ketone resin, polystyrene resin, polyacrylamide resin, polyimide resin, polyamide. Examples thereof include imide resins, and these can be used after being crosslinked. Furthermore, a siloxane-based resin having a charge transporting property and having a crosslinked structure can also be used as a protective layer. In the case of a cured siloxane resin film containing a charge transporting compound, any known material can be used as the charge transporting compound. For example, JP-A-10-95787, JP-A-10-251277, Examples thereof include, but are not limited to, compounds disclosed in JP-A-11-32716, JP-A-11-38656, and JP-A-11-236391.

  Next, the electrophotographic apparatus and the process cartridge of the present invention will be described.

  FIG. 3 is a cross-sectional view schematically showing a basic configuration of a preferred embodiment of the electrophotographic apparatus of the present invention. An electrophotographic apparatus 200 shown in FIG. 3 includes an electrophotographic photosensitive member 1 of the present invention, a contact charging type charging device (contact charging device) 208 for charging the electrophotographic photosensitive member 1, and a power source connected to the charging device 208. 209, an exposure device 210 that exposes the electrophotographic photosensitive member 1 charged by the charging device 208 to form an electrostatic latent image, and a toner image obtained by developing the electrostatic latent image formed by the exposure device 210 with toner. , A transfer device 212 that transfers a toner image formed by the development device 211 to the transfer medium 500, a cleaning device 213, a static eliminator 214, and a fixing device 215. In this case, the static eliminator 214 may not be provided.

  The contact charging device 208 has a charging roll, and a voltage is applied to the charging roll when the photoreceptor 1 is charged. As the voltage range, the DC voltage is preferably positive or negative 50 to 2000 V, more preferably 100 to 1500 V, depending on the required photoreceptor charging potential. When the AC voltage is superimposed, the peak-to-peak voltage is 400 to 1800 V, preferably 800 to 1600 V, and more preferably 1200 to 1600 V. The frequency of the AC voltage is 50 to 20,000 Hz, preferably 100 to 5,000 Hz.

  As the charging roll, one provided with an elastic layer, a resistance layer, a protective layer, etc. on the outer peripheral surface of the core material is preferably used. The charging roll rotates at the same peripheral speed as that of the photosensitive member without contacting the photosensitive member 1 by contacting the photosensitive member 1 and functions as a charging unit. It may be charged by rotating at different peripheral speeds. Instead of the charging roll, a conductive member having a brush shape, a blade shape, or a pin electrode shape may be used. The applied voltage may be a DC voltage or a DC voltage with an AC voltage superimposed on it. Further, a non-contact charging type charging device such as corotron or scorotron may be used.

  As the exposure apparatus 210, an optical system apparatus that can expose a light source such as a semiconductor laser, an LED (light emitting diode), a liquid crystal shutter, or the like on the surface of the electrophotographic photosensitive member in a desired image manner can be used.

  As the developing device 211, a conventionally known developing device using a regular or reversal developer such as a one-component system or a two-component system can be used. The shape of the toner used in the developing device 211 is not particularly limited, and it can be used even if it is indefinite, spherical, or any other specific shape.

  Examples of the transfer device 212 include a roller-type contact charging member, a contact-type transfer charger using a belt, a film, a rubber blade, or the like, or a scorotron transfer charger or a corotron transfer charger using corona discharge. It is done.

  The cleaning device 213 is for removing residual toner adhering to the surface of the electrophotographic photosensitive member after the transfer process. The cleaned electrophotographic photosensitive member is repeatedly used for the image forming process described above. . As the cleaning device, brush cleaning, roll cleaning, and the like can be used in addition to the cleaning blade. Among these, it is preferable to use the cleaning blade. Examples of the material for the cleaning blade include urethane rubber, neoprene rubber, and silicone rubber.

  The electrophotographic apparatus of the present invention may further include an erase light irradiation device 214 as shown in FIG. As a result, when the electrophotographic photosensitive member is repeatedly used, the phenomenon that the residual potential of the electrophotographic photosensitive member is brought into the next cycle is prevented, so that the image quality can be further improved.

  FIG. 4 is a sectional view schematically showing a basic configuration of another embodiment of the electrophotographic apparatus of the present invention. An electrophotographic apparatus 220 shown in FIG. 4 is an intermediate transfer type electrophotographic apparatus. In the housing 400, four electrophotographic photoreceptors 1a to 1d (for example, the electrophotographic photoreceptor 1a is yellow and the electrophotographic photoreceptor 1b is magenta). The electrophotographic photosensitive member 1c can form an image of cyan and the electrophotographic photosensitive member 1d can form a black color), which are arranged in parallel with each other along the intermediate transfer belt 409.

  Here, each of the electrophotographic photoreceptors 1a to 1d mounted on the electrophotographic apparatus 220 is the electrophotographic photoreceptor of the present invention.

  Each of the electrophotographic photoreceptors 1a to 1d can be rotated in a predetermined direction (counterclockwise on the paper surface), and the charging rolls 402a to 402d, the developing devices 404a to 404d, and the primary transfer roll 410a along the rotation direction. To 410d and cleaning blades 415a to 415d are arranged. Each of the developing devices 404a to 404d can be supplied with toner of four colors of black, yellow, magenta and cyan accommodated in the toner cartridges 405a to 405d, and the primary transfer rolls 410a to 410d are respectively intermediate transfer belts. 409 is in contact with the electrophotographic photoreceptors 1a to 1d.

  Further, a laser light source (exposure device) 403 is disposed at a predetermined position in the housing 400, and the surfaces of the charged electrophotographic photoreceptors 1a to 1d are irradiated with laser light emitted from the laser light source 403. Is possible. Thus, the charging, exposure, development, primary transfer, and cleaning processes are sequentially performed in the rotation process of the electrophotographic photoreceptors 1a to 1d, and the toner images of the respective colors are transferred onto the intermediate transfer belt 409 in an overlapping manner.

  The intermediate transfer belt 409 is supported with a predetermined tension by a drive roll 406, a backup roll 408, and a tension roll 407, and can rotate without causing deflection due to the rotation of these rolls. Further, the secondary transfer roll 413 is disposed so as to contact the backup roll 408 via the intermediate transfer belt 409. The intermediate transfer belt 409 passing between the backup roll 408 and the secondary transfer roll 413 is cleaned by, for example, a cleaning blade 416 disposed in the vicinity of the drive roll 406 and then repeatedly used for the next image forming process. Is done.

  A tray (transfer medium tray) 411 is provided at a predetermined position in the housing 400, and the transfer medium 500 such as paper in the tray 411 is transferred to the intermediate transfer belt 409 and the secondary transfer roll by the transfer roll 412. Then, the paper is sequentially transferred between the two fixing rolls 414 that are in contact with each other and the two fixing rolls 414, and then discharged to the outside of the housing 400.

  In the above description, the case where the intermediate transfer belt 409 is used as the intermediate transfer member has been described. However, the intermediate transfer member may have a belt shape like the intermediate transfer belt 409 or a drum shape. Also good. In the case of a belt shape, a conventionally known resin can be used as the resin material used as the base material of the intermediate transfer member. For example, polyimide resin, polycarbonate resin (PC), polyvinylidene fluoride (PVDF), polyalkylene terephthalate (PAT), ethylenetetrafluoroethylene copolymer (ETFE) / PC, ETFE / PAT, PC / PAT blend material, polyester Resin materials such as polyether ether ketone and polyamide, and resin materials using these as main raw materials. Furthermore, a resin material and an elastic material can be blended and used.

  FIG. 5 is a cross-sectional view schematically showing a basic configuration of a preferred embodiment of a process cartridge including the electrophotographic photosensitive member of the present invention. In addition to the electrophotographic photosensitive member 1, the process cartridge 300 includes a charging device 208, a developing device 211, a cleaning device (cleaning unit) 213, an opening 218 for exposure, and an opening 217 for static elimination exposure. Are combined and integrated with each other.

  The process cartridge 300 is detachable from an electrophotographic apparatus main body including a transfer device 212, a fixing device 215, and other components not shown, and the electrophotographic apparatus together with the electrophotographic apparatus main body. It constitutes.

  According to such an electrophotographic apparatus and a process cartridge, by using the electrophotographic photosensitive member 1 (or 1a to 1d) in which electrophotographic characteristics and durability are compatible at a high level, good image quality can be obtained over a long period of time. Can be obtained.

  The transfer medium according to the present invention is not particularly limited as long as it is a medium that transfers a toner image formed on an electrophotographic photosensitive member. For example, when transferring directly from an electrophotographic photosensitive member to a transfer medium such as paper, paper or the like is the transfer medium. When an intermediate transfer member is used, the intermediate transfer member is a transfer medium.

  EXAMPLES Hereinafter, although this invention is demonstrated more concretely based on an Example and a comparative example, this invention is not limited to a following example at all.

(Example 1)
First, an 84 mmφ aluminum base roughened by a honing process was prepared as a conductive base.

  Next, to 170 parts by weight of n-butyl alcohol in which 4 parts by weight of polyvinyl butyral resin (S-REC BM-S, manufactured by Sekisui Chemical Co., Ltd.) is dissolved, 30 parts by weight of an organic zirconium compound (acetylacetone zirconium butyrate) and an organic silane compound (γ -Aminopropyltrimethoxysilane) 3 parts by weight was added, mixed and stirred to obtain a coating solution for forming an undercoat layer. This coating solution was dip coated on the substrate and air-dried at room temperature for 5 minutes. Further, the substrate was heated to 50 ° C. in 10 minutes, placed in a constant temperature and humidity chamber of 50 ° C. and 85% RH (dew point 47 ° C.), and subjected to humidification hardening acceleration treatment for 20 minutes. Then, it put into the hot air dryer and dried for 10 minutes at 170 degreeC.

  Next, a mixture of 15 parts by weight of gallium chloride phthalocyanine as a charge generating material, 10 parts by weight of vinyl chloride-vinyl acetate copolymer resin (VMCH, manufactured by Nippon Union Carbide) and 300 parts by weight of n-butyl alcohol was sand milled. For 4 hours. The obtained dispersion was dip-coated on the undercoat layer and dried to form a charge generation layer having a thickness of 0.2 μm.

  Next, 20 parts by weight of N, N'-bis (3-methylphenyl) -N, N'-diphenylbenzidine, 20 parts by weight of N, N'-bis (3,4-dimethylphenyl) biphenyl-4-amine, and After fully dissolving and mixing 60 parts by weight of bisphenol Z polycarbonate resin (molecular weight 40,000) in 280 parts by weight of tetrohydrofuran and 120 parts by weight of toluene, 10 parts by weight of tetrafluoroethylene resin particles and a fluorine-based dispersion aid. 0.3 parts by weight of the graft polymer was added and further mixed, and then dispersed with a sand grinder using glass beads to obtain a tetrafluoroethylene resin particle dispersion. At this time, the used tetrafluoroethylene resin particles were sampled, and the average sphericity was measured by performing image analysis of the SEM photograph obtained by the electron microscope using a scanning electron microscope and an image analyzer. The obtained results are shown in Table 1. Further, an appropriate amount of the tetrafluoroethylene resin particle dispersion was sampled, and the amount of coarse particles of 1 μm or more present in the dispersion was measured with a particle size distribution measuring device (LA-700 manufactured by Horiba Seisakusho). The obtained results are shown in Table 1. The amount of coarse particles of 1 μm or more indicates the amount of fluorinated resin particle aggregates. The smaller the amount of coarse particles, the more uniform the dispersion of the fluorinated resin particles in the surface layer, and the durability against abrasion and scratches. This means that the releasability with respect to the toner is high.

  The thus obtained tetrafluoroethylene resin particle dispersion liquid is dip-coated on the charge generation layer as a charge transport layer forming coating liquid and dried to form a charge transport layer having a thickness of 26 μm. The intended electrophotographic photoreceptor was obtained.

  Next, using the obtained photoreceptor, an electrophotographic apparatus shown in FIG. 4 was produced. Elements other than the photoreceptor are the same as those of Fuji Xerox's full color printer Docu Print C620.

  Using the electrophotographic apparatus thus obtained, a print test of 500,000 sheets in A4 size and monochrome was performed in an environment of 28 ° C. and 85% RH. The residual potential (VRp) after static elimination was measured for the photoreceptor after the initial printing test and after printing 500,000 sheets, and the difference (ΔRp) between the initial residual potential and the residual potential after printing 500,000 sheets was calculated. . The obtained results are shown in Table 1. It can be determined that the smaller the ΔRp is, the more stable electrophotographic characteristics are.

(Example 2)
The process up to formation of the charge generation layer was performed in the same manner as in Example 1.

  Next, 20 parts by weight of N, N'-bis (3-methylphenyl) -N, N'-diphenylbenzidine, 20 parts by weight of N, N'-bis (3,4-dimethylphenyl) biphenyl-4-amine, and After fully dissolving and mixing 60 parts by weight of bisphenol Z polycarbonate resin (molecular weight 40,000) in 280 parts by weight of tetrohydrofuran and 120 parts by weight of toluene, 4 parts by weight of tetrafluoroethylene resin particles and a fluorine-based dispersion aid. 0.04 part by weight of the graft polymer was added and further mixed, and then dispersed with a sand grinder using glass beads to prepare a tetrafluoroethylene resin particle dispersion. At this time, in the same manner as in Example 1, the average sphericity of the tetrafluoroethylene resin particles and the amount of coarse particles of 1 μm or more present in the dispersion were measured. The obtained results are shown in Table 1.

  Next, the obtained dispersion was dip-coated on the charge generation layer and dried to form a charge transport layer having a thickness of 26 μm, thereby obtaining an intended electrophotographic photoreceptor.

  Next, an electrophotographic apparatus was produced in the same manner as in Example 1 except that the obtained photoreceptor was used, and ΔRp was determined by a continuous print test. The obtained results are shown in Table 1.

(Example 3)
The process up to formation of the charge generation layer was performed in the same manner as in Example 1.

  Next, a tetrafluoroethylene resin particle dispersion was prepared in the same manner as in Example 1 except that 4 parts by weight of the tetrafluoroethylene resin particles and 0.2 parts by weight of the fluorine-based graft polymer were used. At this time, in the same manner as in Example 1, the average sphericity of the tetrafluoroethylene resin particles and the amount of coarse particles of 1 μm or more present in the dispersion were measured. The obtained results are shown in Table 1.

  Next, the obtained dispersion was dip-coated on the charge generation layer and dried to form a charge transport layer having a thickness of 26 μm, thereby obtaining an intended electrophotographic photoreceptor.

  Next, an electrophotographic apparatus was produced in the same manner as in Example 1 except that the obtained photoreceptor was used, and ΔRp was determined by a continuous print test. The obtained results are shown in Table 1.

(Example 4)
The process up to formation of the charge generation layer was performed in the same manner as in Example 1.

  Next, a tetrafluoroethylene resin particle dispersion was prepared in the same manner as in Example 1 except that 16 parts by weight of the tetrafluoroethylene resin particles and 0.16 part by weight of the fluorine-based graft polymer were used. At this time, in the same manner as in Example 1, the average sphericity of the tetrafluoroethylene resin particles and the amount of coarse particles of 1 μm or more present in the dispersion were measured. The obtained results are shown in Table 1.

  Next, the obtained dispersion was dip-coated on the charge generation layer and dried to form a charge transport layer having a thickness of 26 μm, thereby obtaining an intended electrophotographic photoreceptor.

  Next, an electrophotographic apparatus was produced in the same manner as in Example 1 except that the obtained photoreceptor was used, and ΔRp was determined by a continuous print test. The obtained results are shown in Table 1.

(Example 5)
The process up to formation of the charge generation layer was performed in the same manner as in Example 1.

  Next, a tetrafluoroethylene resin particle dispersion was prepared in the same manner as in Example 1 except that 16 parts by weight of the tetrafluoroethylene resin particles and 0.8 parts by weight of the fluorine-based graft polymer were used. At this time, in the same manner as in Example 1, the average sphericity of the tetrafluoroethylene resin particles and the amount of coarse particles of 1 μm or more present in the dispersion were measured. The obtained results are shown in Table 1.

  Next, the obtained dispersion was dip-coated on the charge generation layer and dried to form a charge transport layer having a thickness of 26 μm, thereby obtaining an intended electrophotographic photoreceptor.

  Next, an electrophotographic apparatus was produced in the same manner as in Example 1 except that the obtained photoreceptor was used, and ΔRp was determined by a continuous print test. The obtained results are shown in Table 1.

(Comparative Example 1)
The process up to formation of the charge generation layer was performed in the same manner as in Example 1.
Next, a tetrafluoroethylene resin particle dispersion was prepared in the same manner as in Example 1 except that the amount of the fluorine-based graft polymer was 0.05 parts by weight. At this time, in the same manner as in Example 1, the average sphericity of the tetrafluoroethylene resin particles and the amount of coarse particles of 1 μm or more present in the dispersion were measured. The obtained results are shown in Table 1.

  Next, the obtained dispersion was dip-coated on the charge generation layer and dried to form a charge transport layer having a thickness of 26 μm, thereby obtaining an intended electrophotographic photoreceptor.

Next, an electrophotographic apparatus was produced in the same manner as in Example 1 except that the obtained photoreceptor was used, and ΔRp was determined by a continuous print test. The obtained results are shown in Table 1.

(Comparative Example 2)
The process up to formation of the charge generation layer was performed in the same manner as in Example 1.

  Next, a tetrafluoroethylene resin particle dispersion was prepared in the same manner as in Example 1 except that the amount of the fluorine-based graft polymer was 0.6 parts by weight. At this time, in the same manner as in Example 1, the average sphericity of the tetrafluoroethylene resin particles and the amount of coarse particles of 1 μm or more present in the dispersion were measured. The obtained results are shown in Table 1.

  Next, the obtained dispersion was dip-coated on the charge generation layer and dried to form a charge transport layer having a thickness of 26 μm, thereby obtaining an intended electrophotographic photoreceptor.

  Next, an electrophotographic apparatus was produced in the same manner as in Example 1 except that the obtained photoreceptor was used, and ΔRp was determined by a continuous print test. The obtained results are shown in Table 1.

(Comparative Example 3)
The process up to formation of the charge generation layer was performed in the same manner as in Example 1.

  Next, a tetrafluoroethylene resin particle dispersion was prepared in the same manner as in Example 1 except that the amount of the fluorine-based graft polymer was 0.5 parts by weight. At this time, in the same manner as in Example 1, the average sphericity of the tetrafluoroethylene resin particles and the amount of coarse particles of 1 μm or more present in the dispersion were measured. The obtained results are shown in Table 1.

  Next, the obtained dispersion was dip-coated on the charge generation layer and dried to form a charge transport layer having a thickness of 26 μm, thereby obtaining an intended electrophotographic photoreceptor.

  Next, an electrophotographic apparatus was produced in the same manner as in Example 1 except that the obtained photoreceptor was used, and ΔRp was determined by a continuous print test. The obtained results are shown in Table 1.

(Comparative Example 4)
The process up to formation of the charge generation layer was performed in the same manner as in Example 1.

  Next, a tetrafluoroethylene resin particle dispersion was prepared in the same manner as in Comparative Example 3 except that tetrafluoroethylene resin particles different from the tetrafluoroethylene resin particles of Example 1 were used. At this time, in the same manner as in Example 1, the average sphericity of the tetrafluoroethylene resin particles and the amount of coarse particles of 1 μm or more present in the dispersion were measured. The obtained results are shown in Table 1.

  Next, the obtained dispersion was dip-coated on the charge generation layer and dried to form a charge transport layer having a thickness of 26 μm, thereby obtaining an intended electrophotographic photoreceptor.

  Next, an electrophotographic apparatus was produced in the same manner as in Example 1 except that the obtained photoreceptor was used, and ΔRp was determined by a continuous print test. The obtained results are shown in Table 1.

(Comparative Example 5)
The formation of the charge generation layer was performed in the same manner as in Example 1.

  Next, a tetrafluoroethylene resin particle dispersion was prepared in the same manner as in Example 1 except that the fluorine-based graft polymer was changed to 0.7 parts by weight. At this time, in the same manner as in Example 1, the average sphericity of the tetrafluoroethylene resin particles and the amount of coarse particles of 1 μm or more present in the dispersion were measured. The obtained results are shown in Table 1.

  Next, the obtained dispersion was dip-coated on the charge generation layer and dried to form a charge transport layer having a thickness of 26 μm, thereby obtaining an intended electrophotographic photoreceptor.

  Next, an electrophotographic apparatus was produced in the same manner as in Example 1 except that the obtained photoreceptor was used, and ΔRp was determined by a continuous print test. The obtained results are shown in Table 1.

1 is a schematic cross-sectional view showing a preferred embodiment of an electrophotographic photoreceptor of the present invention. It is a schematic cross section which shows other embodiment of the electrophotographic photoreceptor of this invention. 1 is a schematic configuration diagram showing a preferred embodiment of an electrophotographic apparatus of the present invention. It is a schematic block diagram which shows other embodiment of the electrophotographic apparatus of this invention. 1 is a schematic configuration diagram showing a preferred embodiment of a process cartridge of the present invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Electrophotographic photoreceptor, 2 ... Conductive substrate, 3 ... Photosensitive layer, 4 ... Undercoat layer, 5 ... Charge generation layer, 6 ... Charge transport layer, 7 ... Protective layer, 208 ... Charging device, 209 ... Power supply, DESCRIPTION OF SYMBOLS 210 ... Exposure device 211 ... Developer, 212 ... Transfer device, 213 ... Cleaning device, 214 ... Staticator, 215 ... Fixing device, 216 ... Mounting rail, 217 ... Opening for static elimination exposure, 218 ... For exposure 300 ... Process cartridge, 400 ... Housing, 402a to 402d ... Charging roll, 403 ... Laser light source (exposure device), 404a to 404d ... Developing device, 405a to 405d ... Toner cartridge, 406 ... Drive roll, 407 ... tension roll, 408 ... backup roll, 409 ... intermediate transfer belt, 410a to 410d ... primary transfer roll, 411 Tray (transfer object tray), 412 ... transfer roll, 413 ... second transfer roller, 414 ... fixing roll, 415 a to 415 d ... cleaning blade 416 ... cleaning blade 500 ... image receiving medium.

Claims (3)

An electrophotographic photosensitive member comprising a conductive substrate and a photosensitive layer formed on the substrate,
The photosensitive layer includes a surface layer containing fluorine resin particles having an average sphericity of 0.95 or more and a fluorine graft polymer on the side farthest from the substrate,
The content of the fluorine-based resin particles is 3 to 15% by weight with respect to the total solid content of the surface layer, and the content of the fluorine-based graft polymer is 1 with respect to the weight of the fluorine-based resin particles. An electrophotographic photosensitive member, characterized in that it is ˜5% by weight. An electrophotographic photoreceptor according to claim 1;
A charging device for charging the photoreceptor;
An exposure device that exposes the charged photoreceptor to form an electrostatic latent image;
A developing device for developing the electrostatic latent image to form a toner image;
A transfer device for transferring the toner image from the photoreceptor to a transfer medium;
An electrophotographic apparatus comprising: An electrophotographic photoreceptor according to claim 1;
A charging device that charges the photosensitive member, a developing device that develops an electrostatic latent image formed by exposing the charged photosensitive member to form a toner image, and a cleaning that removes residual toner from the photosensitive member after transfer At least one selected from the apparatus;
A process cartridge comprising:

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