JP2008216929A - Electrophotographic photoreceptor and electrophotographic device using electrophotographic photoreceptor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrophotographic photoreceptor capable of avoiding problems in anodic coating by removing a defect on a base body of a photoreceptor with a method other than the anodic coating and capable of suppressing the degradation of image quality caused by leakage of electric current due to the defect. <P>SOLUTION: The electrophotographic photoreceptor comprises a photosensitive layer formed on a conductive base body via an under coating layer, wherein the under coating layer is formed in a film thickness of 10 μm or more, and white pigment containing metal oxide of average particle size of 0.18 μm or less is dispersed in the under coating layer. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an electrophotographic photoreceptor and an electrophotographic apparatus for forming an image using the electrophotographic photoreceptor.

  2. Description of the Related Art Conventionally, in an electrophotographic apparatus that forms an image using an electrophotographic method such as an electrophotographic printer, generally a charging process for uniformly charging the surface of a photoconductor and an electrostatic latent image are formed on the photoconductor. An image writing step, a developing step of forming a toner image by adhering toner to an image portion of the electrostatic latent image, a transfer step of transferring the toner image on the photosensitive member to a transfer material, An image is formed by a fixing process for fixing the toner image and a cleaning process for cleaning the toner remaining on the photoreceptor after the transfer process is completed. In some cases, after the transfer process is completed and before the next charging process is started, a charge eliminating process is provided to prevent the formation of an afterimage on the photoreceptor. In the charging step and the transfer step, charging and transfer are generally performed by corona discharge.

  However, when corona discharge is used, there is a problem that ozone is generated. Therefore, an ozone-free process has been proposed in which the generation of ozone is suppressed by performing charging and transfer using a charging roller and a transfer roller. For example, a charging roller is pressed onto the photosensitive member, and a voltage is applied to the charging roller to charge the photosensitive member. In addition, a transfer material is superimposed on a toner image formed on the photosensitive member by development, a transfer roller is pressed against the toner image, and a voltage having a polarity opposite to that of the toner is applied to the transfer roller. As a result, an electric field is generated in the gap between the transfer material and the upper layer portion of the toner image, and the toner image is transferred to the transfer material by the electrostatic force of the electric field.

  In addition, when the contact charging method or the transfer roller method described above is applied to a conventional photosensitive member, the charging roller or the transfer roller is in direct contact with the photosensitive layer of the photosensitive member. Otherwise, current leakage may concentrate and the photoreceptor may be damaged. In addition, if there is foreign matter adhesion, dirt, burrs, fine protrusions, holes, or the like on the base portion of the photoconductor, the photoconductor may be damaged due to the concentration of current through the photoconductive layer.

  Therefore, conventionally, in consideration of damage to the photoreceptor due to current concentration, when the photoreceptor is an aluminum substrate, the surface of the substrate is anodized (hereinafter referred to as alumite treatment), and the surface is stained. Patent Document 1 proposes a method for removing the influence of image defects caused by contact charging or local defects of the photosensitive layer by removing defects such as protrusions, protrusions, scratches, and dents.

In addition, an undercoat layer made of an organic resin layer is provided on the surface of the substrate, the thickness of the undercoat layer is 4 μm or more, the thickness of the charge transport layer is 20 μm or less, and the charging potential is the thickness of the thickness of the charge transport layer. Japanese Patent Application Laid-Open No. H10-228688 proposes to stabilize the charged potential of the photosensitive member over a long period of time by setting the potential proportional to the thickness.
Japanese Patent No. 2661418 JP 2000-314976 A

  However, in the method described in Patent Document 1, a method in which the charging roller and the photosensitive member are in direct contact is adopted, and when the photosensitive member is an aluminum base, an adverse effect on the photosensitive member is avoided by anodizing. However, since the number of man-hours for anodizing increases significantly, the cost of the photoconductor increases. Further, in the alumite treatment, problems such as the adverse effect on the environment have been newly generated because a large amount of an acidic solvent is used.

  Further, in the method described in Patent Document 2, if the charge transport layer is greatly worn when the photoconductor is used for a long time, a voltage (anti-resistance) is prevented against a voltage applied from the charging device. Leakage voltage) decreases. In general, the charge transport layer has pinholes during manufacturing, and when damaged from the outside, cracks may occur deep into the film, so that current leakage occurs from the charging and transfer contact members. The photoconductor may be damaged due to concentration of the toner.

  In particular, many of the conventional undercoat layers are constituted by dispersing titanium oxide having an average particle size of 0.25 μm in an organic resin, and the thickness of the undercoat layer is about 1 to 4 μm for practical use. Has been. An electrophotographic photosensitive member has been proposed in which the thickness of the undercoat layer is increased to prevent leakage. However, simply increasing the thickness of the undercoat layer can prevent the above leakage due to the uneven distribution of titanium oxide dispersed in the organic resin layer. However, the current situation is that it has not been effective enough. In addition, if the film thickness is simply increased as in the prior art, the resistance of the undercoat layer increases and the residual potential increases when the photosensitive member is exposed, resulting in a disadvantage that a sufficient print density cannot be obtained. there were.

  Therefore, the present invention eliminates the problems in the alumite processing by removing defects on the substrate of the photosensitive member by a method other than the alumite processing, and suppresses the deterioration in image quality due to current leakage caused by the defects. An electrophotographic photosensitive member and an electrophotographic apparatus for forming an image using the electrophotographic photosensitive member are provided.

  In order to solve the above problems, an electrophotographic photosensitive member according to the present invention is an electrophotographic photosensitive member in which a photosensitive layer is formed on a conductive support through an undercoat layer, and the undercoat layer is a first lower layer. It has a two-layer structure of a subbing layer and a second subbing layer, the first subbing layer is formed to a thickness of 10 μm or more, and the first subbing layer has an average particle size of 0.18 μm or less. A white pigment containing the metal oxide is dispersed.

  The electrophotographic apparatus of the present invention is characterized by applying a voltage of 1500 V or less in absolute value to the electrophotographic photosensitive member having the above structure.

  According to the electrophotographic photosensitive member of the present invention, since the thickness of the undercoat layer is 10 μm or more in the initial state, even if the photosensitive member is charged by the contact charging member, it has a sufficient withstand voltage against voltage. Even if foreign matter adheres to the base portion of the photosensitive member, dirt, burrs, fine protrusions, holes, or the like, the photosensitive member is not damaged by the concentration of current at the defective portion. In addition, when the photoreceptor is used for a long period of time, conventionally, the metal oxide dispersed in the undercoat layer may agglomerate and cause a local decrease in resistance value. As described above, by setting the particle size of the metal oxide to 0.18 μm or less, aggregation of the metal oxide can be avoided. Furthermore, since the metallic white pigment is dispersed in the undercoat layer, the cost can be reduced as compared with the conventional alumite treatment method, and a strongly acidic solvent associated with the alumite treatment is not used. This makes it possible to produce photoconductor drums with environmentally friendly equipment.

  Further, according to the electrophotographic apparatus of the present invention, since an absolute voltage of 1500 V or less is applied to the electrophotographic photosensitive member, current leakage on the photosensitive member is less likely to occur, and the quality of the printed image is improved. We were able to plan.

Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to the drawings.
FIG. 1 is an explanatory diagram showing an example of an electrophotographic apparatus to which the image forming method employed in the present invention can be applied. In this electrophotographic apparatus, a photosensitive drum 21 as a photosensitive member is mounted so as to be rotatable in the direction of arrow A. The photosensitive drum 21 is obtained by providing a photoconductive layer on a conductive substrate. The photoconductive layer is composed of, for example, an organic photoreceptor, a selenium photoreceptor, a zinc oxide photoreceptor, an amorphous silicon photoreceptor, or the like. Among these, organic photoconductors (OPC) are representative.

  Around the photosensitive drum 21, a charging roller 22 as a charging member, a laser beam irradiation device 23 as an exposure device, a developing device 29, a transfer roller 210, and a cleaning blade 212 are arranged along the circumferential direction. . The charging step is a step of uniformly charging the surface of the photosensitive drum 21 positively or negatively by the charging roller 22. In addition to the charging roller 22 shown in FIG. 1, there is a charging method using a fur brush, a magnetic brush, a blade, or the like, and the charging roller 22 can be replaced with these.

  In the exposure process, the surface of the photosensitive drum 21 is irradiated with light corresponding to the image signal by a laser beam irradiation device 23 as shown in FIG. This is a step of forming an electrostatic latent image. The laser beam irradiation device 23 is composed of, for example, a laser irradiation device and an optical system lens. In addition to the laser beam irradiation device 23, an LED irradiation device can also be used as the exposure device.

  The developing process is a process in which toner (developer) is attached to the electrostatic latent image formed on the surface of the photosensitive drum 21 by the exposure process by the developing device 29. In the reverse development, a bias voltage is applied between the developing roller 24 and the photosensitive drum 21 so that the toner is attached only to the light irradiation portion, and in the normal development, the toner is attached only to the light non-irradiation portion. .

  The developing device 29 shown in FIG. 1 is used for a one-component contact development system using toner. A developing roller 24 and a supply roller 26 are disposed in a casing 27 that contains toner 28. The developing roller 24 is disposed so as to partially contact the photosensitive drum 21, and rotates in the direction B opposite to the photosensitive drum 21. The supply roller 26 contacts the developing roller 24 and rotates in the same direction C as the developing roller 24, and supplies toner 28 to the outer periphery of the developing roller 24. Other development methods include a one-component non-contact development method, a two-component contact development method, and a two-component non-contact development method.

  Around the developing roller 24, a developing roller blade 25 as a toner layer thickness regulating member is disposed at a position between the contact point with the supply roller 26 and the contact point with the photosensitive drum 21. The developing roller blade 25 is made of, for example, a conductive rubber elastic body or metal.

  The transfer process is a process of transferring the toner image on the surface of the photosensitive drum 21 formed in the developing process onto a transfer material 211 such as paper. In the transfer process, transfer is usually performed using a transfer roller 210 as shown in FIG. 1, but there are also belt transfer and corona transfer.

  The cleaning process is a process for cleaning the toner remaining on the surface of the photosensitive drum 21 after the transfer process. In the cleaning process, a cleaning blade 212 as shown in FIG. 1 is generally used, but cleaning with a fur brush or a magnetic brush is also possible. In the present invention, the cleaning blade 212 is used for cleaning. After the transfer process, the transfer material having the toner image is transferred to the fixing process. In the fixing process, for example, the transfer material is passed between the fixing roller 213 and the pressure roller 214, and the toner image is fixed on the transfer material by heating and pressing.

  In the image forming apparatus shown in FIG. 1, the surface of the photosensitive drum 21 is uniformly charged negatively by the charging roller 22, and then an electrostatic latent image is formed by the laser light irradiation device 23. Development is performed by the device 29 to form a toner image. The toner image on the photosensitive drum 21 is transferred onto a transfer material such as paper by the transfer roller 210, and the toner remaining on the surface of the photosensitive drum 21 (transfer residual toner) is cleaned by the cleaning blade 212. . After the cleaning process, the next image forming cycle starts.

  The image forming apparatus shown in FIG. 1 is for monochrome use, but the image forming method of the present invention can also be applied to a color image forming apparatus such as a copying machine or a printer that forms a color image. As a color image forming apparatus, a multi-development system in which a multi-color toner image is developed on a photosensitive member and transferred to a transfer material at a time, a single-color toner image is developed on the photosensitive member, and then a transfer material There is a multiple transfer system in which the transfer process is repeated for the number of colors of the color toner. In the multiple transfer method, a transfer material is wound around a transfer drum and transferred for each color, and a primary transfer is performed for each color on an intermediate transfer member to form a multicolor image on the intermediate transfer member. After that, the intermediate transfer system that performs secondary transfer in a batch, the tandem system that arranges the photosensitive material for each color in tandem, sucks and conveys the transfer material by the transfer conveyance belt, and sequentially transfers each color to the transfer material There is. Among these transfer systems, the tandem system is preferable because the image forming speed can be increased.

  The charging roller 22 rotates while contacting the photosensitive drum 21. The rotational driving force may be applied from the outside, or may be rotated by the contact frictional force with the photosensitive drum 21. As a material of the charging roller 22, a rubber member that is a conductive or semiconductive elastic body is suitable. As the rubber material, NBR, EPDM, silicon rubber, neoprene rubber, epichlorohydrin rubber, natural rubber, and those in which conductive particles such as carbon are kneaded are used.

When such a contact charging device is used, the uniformity of charging is important. If the resistance of the charging roller 22 is too small, charging unevenness of the photosensitive drum 21 occurs, causing image unevenness and fogging. On the other hand, if the resistance is too large, charging failure occurs and the latent image carrier is not sufficiently charged. Therefore, the resistance of the charging roller 22 is preferably 10 ² to 10 ¹⁰ Ωcm, and more preferably 10 ⁴ to 10 ⁸ .

Further, the surface of the charging roller 22 may be overcoated. As the material for the overcoat, polyamide resin, fluororesin, vinyl chloride resin, acrylic resin, polyester resin, or the like is used. The resistance of the overcoat member is preferably 10 ³ to 10 ¹² Ωcm, and more preferably 10 ⁵ to 10 ¹⁰ Ωcm. The film thickness of the overcoat member is usually 0.01 μm to 1000 μm, preferably 0.1 μm to 500 μm. Examples of overcoat methods include dipping, spraying, vacuum deposition, and plasma coating. Among these, the dip method is suitable for mass production.

  A DC voltage is suitable for the voltage applied to the charging roller 22 to charge the photosensitive drum 21. The application range of the DC voltage is a positive or negative voltage of 600 V to 2000 V, preferably 600 V to 1500 V. There is also a method in which an AC voltage is superimposed on a DC voltage, but this is not preferable from the viewpoint of current leakage to the photosensitive drum 21.

  The electrophotographic photoreceptor of the present invention has a function in which, for example, a charge generation layer containing at least a charge generation agent is formed on a conductive substrate, and a charge transfer layer containing at least a charge transfer agent is formed thereon. It is a separation type photoreceptor. In this case, a photosensitive layer is formed by the charge generation layer and the charge transfer layer. Further, as an electrophotographic photosensitive member, a single layer type photosensitive member in which a charge generation agent and a charge transfer agent are contained in the same layer, a reverse lamination type photosensitive member in which a charge transfer layer and a charge generation layer are stacked in this order, etc. Can also be used.

  As the conductive substrate used in the present invention, for example, a single metal such as aluminum, brass, stainless steel, nickel, chromium, titanium, gold, silver, copper, tin, platinum, molybdenum, indium, or processing of these alloys Body, conductive plates such as metal and carbon, etc. treated by vapor deposition, plating, etc. to give conductivity, plastic plates and films, conductive glass coated with tin oxide, indium oxide, aluminum iodide, etc. There are no restrictions on the type or shape. The conductive substrate can be formed using various conductive materials. As for the shape of the conductive substrate, various shapes such as a drum shape, a rod shape, a plate shape, a sheet shape, and a belt shape can be used.

  Among conductive substrates, aluminum alloys such as JIS3000, JIS5000, and JIS6000 are used, EI method (ironing after extrusion), ED method (drawing after extrusion), DI method (ironing after deep drawing) Machining), II method (shock processing after impact extrusion), and non-cutting pipes that are not subjected to surface treatment such as diamond cutting or surface treatment such as polishing, It is preferable from the viewpoint of the lower layer forming process. The diameter of the non-cutting tube is usually 16 to 40 mm, and the thickness is usually about 0.5 to 2.5 mm.

  In the electrophotographic photoreceptor of the present invention, an undercoat layer using a resin material is provided on a conductive substrate. By providing the undercoat layer, adverse effects due to defects on the surface of the conductive substrate can be suppressed, and a new function can be imparted.

  As an undercoat layer (UCL) using a resin material, for example, polyethylene, polypropylene, polystyrene, acrylic resin, vinyl chloride resin, vinyl acetate resin, polyurethane resin, epoxy resin, silicone resin, polyamide resin, polyimide Resin or the like is used. Among these resins, a polyimide resin is particularly preferable. The thickness of the undercoat layer using a resin material is usually 10 μm to 50 μm, preferably 10 to 30 μm, and more preferably 10 to 20 μm.

  In general, a polyimide resin is produced by condensation polymerization of a dianhydride of tetracarboxylic acid and an aromatic diamine. After applying an intermediate polyamic acid solution to an object, it is usually dried at 200 ° C. or higher. At that time, a dehydrogenation reaction takes place to form a polyimide. However, in the undercoat layer of the present invention, all of the intermediate before imidization and the imidized polyimide are mixed and used without being polyimideized. For this reason, after mixing white pigments, such as a titanium oxide, with the solution of polyamic acid, and coating the solution, it is made to dry between 110 to 170 degreeC, and the intermediate body before imidation (henceforth, polyimide) A precursor (hereinafter referred to as a “precursor”) and an imidized polyimide (hereinafter referred to as a polyimide resin) were produced to form an undercoat layer.

  As for the mixing ratio of the polyimide precursor and the polyimide resin, for example, the ratio of the polyimide resin is 20% to 70%, preferably 30% to 50% of the total weight of the polyimide resin and the polyimide precursor. If the proportion of the polyimide resin is less than 20%, the undercoat layer dissolves in the organic solvent. Conversely, if the proportion exceeds 70%, the state becomes close to imidization, and the residual potential after the repetition is accumulated. Or a thin darkening of the white background (fogging). The molecular weight of the polyimide precursor and the polyimide resin is preferably in the range of 10,000 to 100,000, particularly 10,000 to 30,000.

  The drying temperature when forming the undercoat layer is preferably in the range of 110 ° C to 170 ° C. Below 110 ° C., the undercoat layer dissolves in the solvent and cannot be applied to the photoconductor. Conversely, when the temperature exceeds 170 ° C., the residual potential after repetition is accumulated and dust and fog are generated. It is.

  In the electrophotographic photoreceptor of the present invention, a metal oxide white pigment is contained in the undercoat layer for the purpose of suppressing light interference during semiconductor laser exposure. Examples of the metal oxide white pigment in the undercoat layer include titanium oxide, zinc oxide, alumina, tin oxide, indium oxide, zirconium oxide, and magnesium oxide. Among these, titanium oxide is preferable. The particle size of these inorganic pigments is usually 0.02 to 0.18 μm, preferably 0.02 to 0.13 μm. Titanium oxide may be obtained by subjecting the surface of titanium oxide particles to various treatments as long as the volume resistance value is not lowered. For example, aluminum, silicon nickel, or the like can be used as a treatment agent to coat the particle surface with an oxide film. In addition, it is possible to impart water repellency with a coupling agent or the like as required.

  When the undercoat layer contains an inorganic pigment, examples of the binder resin include thermoplastic resins such as polyvinyl alcohol, casein, sodium polyacrylate, copolymer nylon, and methoxymethylated nylon; polyurethane resins, melamine resins, Examples thereof include thermosetting resins such as epoxy resins, alkyd resins, phenol resins, butyral resins, and unsaturated polyester resins. As the binder resin, it is also preferable to use a resin material constituting the undercoat layer such as a polyimide resin.

  By setting the thickness of the undercoat layer to 10 μm or more, it becomes possible to make the thickness of the photosensitive layer and the undercoat layer of the photoconductor thicker than before. Since the electrostatic attraction force of the toner to the photoconductor is inversely proportional to the thickness of the photosensitive layer and the undercoat layer, the thickness of the photosensitive layer is preferably as large as possible to reduce the electrostatic attraction force. In order to form an electrostatic latent image with higher definition than before, the thickness of the photosensitive layer and the undercoat layer may be reduced. In this case, if the thickness of the undercoat layer is increased more than the thinned photosensitive layer. The electrostatic attraction force of the toner to the photoreceptor can be reduced.

Next, leakage of applied voltage and current in contact charging with respect to the thickness of the undercoat layer of the photoreceptor will be described.
The undercoat layer is a layer that is directly applied to the surface of the conductive substrate. Generally, the conductive substrate is formed by a general method such as an EI method (ironing after extrusion molding) using an aluminum alloy such as JIS 3000, JIS 5000, or JIS 6000. That is, a non-cutting tube that is not subjected to surface treatment such as diamond cutting or surface treatment such as polishing is often used. The same applies to the cutting tube, but innumerable irregularities and protrusions are seen on the surface of the conductive substrate. Rz = 0.5 to 1 μm in terms of roughness and Ry = 1 to 3 μm in terms of maximum height. Is common. Therefore, in order to cover defects (irregularities and protrusions) on the surface of the conductive substrate, a thickness of the undercoat layer of about 4 μm is required.

Therefore, an undercoat layer of 4 μm or more is applied on a conductive substrate made of an aluminum alloy, the thickness of the undercoat layer, the voltage applied to the contact charging device, and the voltage until the undercoat layer leaks. I investigated the relationship. As the contact charging device, a charging roller made of epichlorohydrin rubber having a volume resistance value of 10 ⁸ Ωcm was used.

  Specifically, titanium oxide particles (trade name: TTO-55, manufactured by Ishihara Sangyo Co., Ltd.) coated with alumina on a cylindrical drum made of uncut aluminum with a diameter of 30 mm and polyimide resin are weighted. A solution mixed at a ratio of 1: 5.9 was applied and dried at 140 ° C. for 30 minutes to form an undercoat layer having a thickness of 2, 4, 6, 8, 10, 12, or 14 μm.

  An earth was taken inside the cylindrical drum, the charging roller 22 was placed on the undercoat layer on the surface, and a DC voltage was applied to the cored bar 22a of the charging roller 22 to examine current leakage. .

  FIG. 2 is a graph showing the thickness of the undercoat layer and the voltage value at which current leaks due to application of a DC voltage. As can be seen from this figure, when the undercoat layer has a thickness of 6 μm or less, current leakage is observed at an absolute value of 100 V or less. Therefore, the leakage generation voltage is 100 V or less as an absolute value. This can be presumed to be due to the occurrence of current leakage at a low voltage due to the effects of irregularities and protrusions on the surface of the cylindrical drum. However, as the thickness of the undercoat layer increases, the leak generation voltage increases. When the thickness of the undercoat layer is 10 μm or more, the leak generation voltage is 1500 V or more in absolute value. That is, in order to set the leak generation voltage in the initial state to 1500 V or more, the thickness of the undercoat layer needs to be 10 μm or more.

  In the case of a general contact charging method, there are many devices in which the voltage applied to the charging roller 22 is about -1100V to -1300V. Preferably, the leak generation voltage is 1500 V or more in absolute value.

  In general photoreceptors, a charge generation layer and a charge transfer layer are provided on an undercoat layer. The charge generation layer has a thickness of about 0.3 μm, but the charge transfer layer has a thickness of about 10 μm to 30 μm. If the thickness of the charge transfer layer is increased, the leakage generation voltage can be apparently increased. However, many charge transfer layers are on the surface of the photoreceptor, and the film is scraped and reduced by use. Therefore, if the charge transfer layer is expected to increase the leakage generation voltage, the photoreceptor cannot be used stably for a long period of time. On the other hand, in order to increase the resolution, it is advantageous that the thickness of the charge transfer layer is smaller. Recently, a clear image is obtained on a photoconductor having a thickness of 20 μm or less. Further, the leakage generation voltage varies depending on the state of titanium oxide as the metal oxide dispersed in the undercoat layer. In general, a substance dispersed in a resin is aggregated by the action of an electric field. When agglomeration occurs, a force-like decrease in resistance is observed, and when the photoreceptor is used for a long time, a large amount of agglomeration occurs when the particle size of the metal oxide dispersed in the undercoat layer is large. However, the particle diameter of the conventional metal oxide is about 0.25 μm, but if this is desirably about half of 0.13 μm or less, aggregation is greatly improved. Therefore, even if the photoconductor is used for a long time, the metal oxide does not aggregate in the undercoat layer, so that the electrical withstand voltage of the undercoat layer is stabilized for a long time.

  As the charge generation agent to be contained in the charge generation layer, disazo pigments and oxytitanium phthalocyanine are desirable in terms of sensitivity, but are not limited thereto. For example, selenium, selenium-tellurium, selenium-arsenic, amorphous silicon, Metal phthalocyanine, other metal phthalocyanine pigments, monoazo pigments, trisazo pigments, polyazo pigments, indigo pigments, selenium pigments, toluidine pigments, pyrazoline pigments, perylene pigments, quinacridone pigments, polycyclic quinone pigments, pyrylium salts, and the like can be used. Oxytitanium phthalocyanine is particularly preferable because of its relatively high sensitivity.

  The film thickness of the charge generation layer is usually 0.01 to 5.0 μm, preferably 0.1 to 1.0 μm, and more preferably 0.2 to 0.5 μm. The charge generators may be used alone or in combination of two or more in order to obtain an appropriate photosensitivity wavelength and sensitizing action.

  Examples of the charge transfer agent contained in the charge transfer layer include polymer charge transfer agents such as polyvinyl carbazole, polyacetylene, polythiophene, polypyrrole, polyphenylene, polyaniline, polyquinoline, polyphenylene sulfide, and polyphthalocyanine. Examples of the low-molecular charge transfer agent include trinitrofluorenone, tetracyanoethylene, quinone, diphenoquinone, anthraquinone, isoxazolidylene and derivatives thereof, polycyclic aromatic compounds such as anthracene and pyrene, indole, carbazole, Examples thereof include nitrogen-containing heterocyclic compounds such as imidazole, pyrazoline, hydrazone, triphenylmethane, triphenylamine, enamine, stilbene, and butadiene compounds.

  The charge transfer agents can be added alone or in combination of two or more. The film thickness of the charge transfer layer is usually 5 to 30 μm, preferably 10 to 20 μm.

  Examples of the binder resin used to form the photosensitive layer include polycarbonate resin, styrene resin, acrylic resin, styrene-acrylic resin, ethylene-vinyl acetate resin, polypropylene resin, vinyl chloride resin, chlorinated polyether, and chloride. Vinyl-vinyl acetate resin, polyester resin, furan resin, nitrile resin, alkyd resin, polyacetal resin, polymethylpentene resin, polyamide resin, polyurethane resin, epoxy resin, polyarylate resin, diarylate resin, polysulfone resin, polyethersulfone resin, Polyallyl sulfone resin, silicone resin, ketone resin, polyvinyl butyral resin, polyether resin, phenol resin, ethylene / vinyl acetate / copolymer (EVA) resin, acrylonitrile / chlorinated polyethylene Styrene (ACS) resin, acrylonitrile butadiene styrene (ABS) resins, photocurable resins such as epoxy arylate and the like.

  These binder resins can be used alone or in combination of two or more. It is more preferable to use a mixture of two or more kinds of resins having different molecular weights as the binder resin because the hardness and the wear resistance can be improved. As the binder resin, a polycarbonate resin is preferable, and a siloxane skeleton-containing polycarbonate copolymer resin, a polycarbonate copolymer resin provided with a perfluoro group as a terminal group, and the like are more preferable.

  The electrophotographic photosensitive member of the present invention contains an antioxidant or an ultraviolet absorber in the photosensitive layer for the purpose of property change due to oxidative deterioration of the photoconductive material or binder resin, prevention of cracks, and improvement of mechanical strength. It is preferable to make it. An antioxidant and an ultraviolet absorber can be added simultaneously. These additives may be added to any layer in the photosensitive layer, but are preferably added to the outermost layer, particularly the charge transfer layer.

  The antioxidant is preferably added in a proportion of 3 to 20% by weight with respect to the binder resin. Moreover, it is preferable to add a ultraviolet absorber in the ratio of 3 to 30 weight% with respect to binder resin. When both the antioxidant and the ultraviolet absorber are added, it is preferable that the addition amount of both components is in the range of 5 to 40% by weight with respect to the binder resin.

  In addition to the antioxidants and ultraviolet absorbers described above, light stabilizers such as hindered amines and hindered phenol compounds, anti-aging agents such as diphenylamine compounds, surfactants, and the like can also be added to the photosensitive layer.

  On the photosensitive layer, an organic thin film made of epoxy resin, melamine resin, fluororesin, silicon resin, etc., or a thin film made of a siloxane structure formed from a hydrolyzate of a silane coupling agent, is formed as a surface protective layer. Also good.

  As a method for forming the photosensitive layer, a method in which a predetermined photosensitive material and a binder resin are dispersed or dissolved in a solvent to prepare a coating solution, and this coating solution is applied to a predetermined surface is generally used. is there. Examples of the coating method include dip coating, curtain flow, bar coating, roll coating, ring coating, spin coating, spray coating, and the like, and can be selected according to the shape of the base and the state of the coating liquid. . The charge generation layer can also be formed by a vacuum evaporation method.

  Examples of the solvent used in the coating solution include alcohols such as methanol, ethanol, n-propanol, i-propanol, butanol, methyl cellosolve, and ethyl cellosolve, pentane, hexane, heptane, octane, cyclohexane, and cycloheptane. Saturated aliphatic hydrocarbons such as, aromatic hydrocarbons such as toluene and xylene, chlorinated hydrocarbons such as dichloromethane, dichloroethane, chloroform and chlorobenzene, ethers such as dimethyl ether, diethyl ether and tetrahydrofuran (THF), acetone, methyl ethyl ketone, Ketones such as methyl isobutyl ketone and cyclohexanone, esters such as ethyl formate, propyl formate, methyl acetate, ethyl acetate, propyl acetate, butyl acetate and methyl propionate, N, N-dimethylphenol Muamido, dimethyl sulfoxide, amides such as N- methyl-2-pyrrolidone. These solvents may be used alone or in combination of two or more.

  Examples of the present invention will be described in detail below.

Example 1
<< Manufacture of photoconductor >>
On a cylindrical drum made of uncut aluminum with a diameter of 30 mm, titanium oxide particles (trade name: TTO-55, manufactured by Ishihara Sangyo Co., Ltd.) coated with alumina and coated with alumina and polyimide resin in a weight ratio of 1: A solution mixed at a rate of 5.9 was applied, and then dried at 140 ° C. for 30 minutes to form a first undercoat layer having a thickness of 20.0 μm. Next, melamine alkyd resin as a thermosetting resin and titanium oxide (trade name: CR-EL, manufactured by Ishihara Sangyo Co., Ltd.) having a particle size of 0.25 μm were dissolved in methyl ethyl ketone and applied at a ratio of 1: 3. Liquid. This coating solution was applied onto the first undercoat layer to form a second undercoat layer having a thickness of 1.0 μm.

  Next, polyvinyl butyral was used as a binder resin, and a dispersion of oxytitanium phthalocyanine was applied by 0.1 μm by dip coating to form a charge generation layer.

  Furthermore, a polycarbonate copolymer as a binder resin, a butadiene compound as a charge transfer agent, and 2,6-di-tert-butyl-4-methylphenol as an antioxidant, a polycarbonate copolymer = 1. A coating solution was prepared by dissolving in chloroform at a weight ratio of 0.0 / 0.8 / 0.18. And after apply | coating this coating liquid by dip coating, it dried at the temperature of 100 degreeC for 1 hour, the charge transfer layer with a film thickness of 20 micrometers was formed, and the electrophotographic photoreceptor was produced.

≪Manufacture of charging roller≫
As shown in FIG. 1, a charging roller 22 having a diameter of 12 mm was manufactured using a stainless steel shaft having a diameter of 6 mm as the core metal 22a and using a 10 ⁸ Ωcm epichlorohydrin rubber as the roller member 22b. Then, the above photoconductor and charging roller were incorporated into a commercially available printer (manufactured by Oki Data, ML5300), and image evaluation was performed. The printer is a contact charging type printer using a charging roller, and -1200 V was applied to the charging roller from the outside.

  As the image pattern, white background, black background, gradation pattern and the like were collected, and it was confirmed that each initial image was good. Next, using A4 printing paper, a continuous printing test was conducted with a printing pattern of 5% density in an environment of a temperature of 23 ° C. and a humidity of 50%. Every 1,000 sheets, white background, black background, gradation pattern These image patterns were collected, and the presence or absence of current leakage was evaluated by visually evaluating black spots and white spots on the images. The continuous test was performed up to 30,000 sheets. After the continuous test, no black spots or white spots were observed in the images of the white background, black background, and gradation pattern. As described above, since no black spot or white spot was seen in each of the white background, black background, and gradation pattern images, it is considered that there was no current leakage in the photoconductor.

Example 2
A charging roller having a diameter of 12 mm was prepared by using a stainless steel shaft having a diameter of 6 mm as the core metal and using a resistance of 10 ⁴ Ωcm epichlorohydrin rubber as the roller member. Other than that, the initial image evaluation was performed in the same manner as in Example 1. As a result, it was confirmed that the images of the white background, the black background, and the gradation pattern were good, and no black spots generated due to the leakage of the current of the photoreceptor were found. Subsequently, 30,000 sheets were continuously tested. Again, it was confirmed that the images of the white background, the black background, and the gradation pattern were good, and no black spots similar to the above were observed.

Example 3
The initial image evaluation was performed in the same manner as in Example 1 except that the bias of the power source applied to the charging roller was set to DC-1500V. As a result, it was confirmed that the images of the white background, the black background, and the gradation pattern were good, and no black spots generated due to the leakage of the current of the photoreceptor were found. Subsequently, 30,000 sheets were continuously tested. Again, it was confirmed that the images of the white background, the black background, and the gradation pattern were good, and no black spots similar to the above were observed.

Example 4
A charging roller having a diameter of 12 mm was prepared by using a stainless steel shaft having a diameter of 6 mm as the core metal and using a resistance of 10 ⁴ Ωcm epichlorohydrin rubber as the support member.

  The initial image evaluation was performed in the same manner as in Example 1 except that the bias of the power source applied to the charging roller was set to DC-1500V. As a result, it was confirmed that the images of the white background, the black background, and the gradation pattern were good, and no black spots generated due to the leakage of the current of the photoreceptor were found. Subsequently, 30,000 sheets were continuously tested. Again, it was confirmed that the images of the white background, the black background, and the gradation pattern were good, and no black spots similar to the above were observed.

Example 5
On a cylindrical drum made of uncut aluminum with a diameter of 30 mm, titanium oxide particles (trade name: TTO-55, manufactured by Ishihara Sangyo Co., Ltd.) coated with alumina and coated with alumina and polyimide resin in a weight ratio of 1: A solution mixed at a rate of 5.9 was applied, and then dried at 140 ° C. for 30 minutes to form a first undercoat layer having a thickness of 10.0 μm. Next, melamine alkyd resin as a thermosetting resin and titanium oxide (trade name: CR-EL, manufactured by Ishihara Sangyo Co., Ltd.) having a particle size of 0.25 μm were dissolved in methyl ethyl ketone and applied at a ratio of 1: 3. The coating solution was applied onto the undercoat layer to form a second undercoat layer having a thickness of 1.0 μm.

  The initial image evaluation was performed in the same manner as in Example 1 except that the bias of the power source applied to the charging roller was set to DC-1500V. As a result, it was confirmed that the images of the white background, the black background, and the gradation pattern were good, and no black spots generated due to the leakage of the current of the photoreceptor were found. Subsequently, 30,000 sheets were continuously tested. Again, it was confirmed that the images of the white background, the black background, and the gradation pattern were good, and no black spots similar to the above were observed.

Example 6
On a cylindrical drum made of non-cut aluminum with a diameter of 30 mm, titanium oxide particles (trade name: TTO-51, manufactured by Ishihara Sangyo Co., Ltd.) coated with alumina and coated with alumina and polyimide resin in a weight ratio of 1: A solution mixed at a rate of 11.8 was applied and then dried at 140 ° C. for 30 minutes to form a first undercoat layer having a thickness of 10.0 μm. Next, melamine alkyd resin as a thermosetting resin and titanium oxide (trade name: CR-EL, manufactured by Ishihara Sangyo Co., Ltd.) having a particle size of 0.25 μm were dissolved in methyl ethyl ketone and applied at a ratio of 1: 3. The coating solution was applied onto the undercoat layer to form a second undercoat layer having a thickness of 1.0 μm.

  The initial image evaluation was performed in the same manner as in Example 1 except that the bias of the power source applied to the charging roller was set to DC-1500V. As a result, it was confirmed that the images of the white background, the black background, and the gradation pattern were good, and no black spots generated due to the leakage of the current of the photoreceptor were found. Subsequently, 30,000 sheets were continuously tested. Again, it was confirmed that the images of the white background, the black background, and the gradation pattern were good, and no black spots similar to the above were observed.

Example 7
Mixing titanium oxide particles (trade name: PT-401M, manufactured by Ishihara Sangyo Co., Ltd.) and polyimide resin in a weight ratio of 1: 3 on a cylindrical drum made of uncut aluminum with a diameter of 30 mm. After applying the solution, it was dried at 140 ° C. for 30 minutes to form a first undercoat layer having a thickness of 10.0 μm. Next, melamine alkyd resin as a thermosetting resin and titanium oxide (trade name: CR-EL, manufactured by Ishihara Sangyo Co., Ltd.) having a particle size of 0.25 μm were dissolved in methyl ethyl ketone and applied at a ratio of 1: 3. The coating solution was applied onto the undercoat layer to form a second undercoat layer having a thickness of 1.0 μm.

  The initial image evaluation was performed in the same manner as in Example 1 except that the bias of the power source applied to the charging roller was set to DC-1500V. As a result, it was confirmed that the images of the white background, the black background, and the gradation pattern were good, and no black spots generated due to the leakage of the current of the photoreceptor were found. Subsequently, 30,000 sheets were continuously tested. Again, it was confirmed that the images of the white background, the black background, and the gradation pattern were good, and no black spots similar to the above were observed.

Example 8
A ratio of 1: 1.8 by weight of titanium oxide particles (trade name: PT-401L, manufactured by Ishihara Sangyo Co., Ltd.) and polyimide resin on a cylindrical drum made of uncut aluminum with a diameter of 30 mm. After coating the mixed solution in (1), it was dried at 140 ° C. for 30 minutes to form a first undercoat layer having a thickness of 10.0 μm. Next, melamine alkyd resin as a thermosetting resin and titanium oxide (trade name: CR-EL, manufactured by Ishihara Sangyo Co., Ltd.) having a particle size of 0.25 μm were dissolved in methyl ethyl ketone and applied at a ratio of 1: 3. The coating solution was applied onto the undercoat layer to form a second undercoat layer having a thickness of 1.0 μm.

  The initial image evaluation was performed in the same manner as in Example 1 except that the bias of the power source applied to the charging roller was set to DC-1500V. As a result, it was confirmed that the images of the white background, the black background, and the gradation pattern were good, and no black spots generated due to the leakage of the current of the photoreceptor were found. Subsequently, 30,000 sheets were continuously tested. Again, it was confirmed that the images of the white background, the black background, and the gradation pattern were good, and no black spots similar to the above were observed.

Example 9
A ratio of 1: 1.3 by weight of titanium oxide particles (trade name: PT-501R, manufactured by Ishihara Sangyo Co., Ltd.) and polyimide resin on a cylindrical drum made of uncut aluminum with a diameter of 30 mm. After coating the mixed solution in (1), it was dried at 140 ° C. for 30 minutes to form a first undercoat layer having a thickness of 10.0 μm. Next, melamine alkyd resin as a thermosetting resin and titanium oxide (trade name: CR-EL, manufactured by Ishihara Sangyo Co., Ltd.) having a particle size of 0.25 μm were dissolved in methyl ethyl ketone and applied at a ratio of 1: 3. The coating solution was applied onto the undercoat layer to form a second undercoat layer having a thickness of 1.0 μm.

  The initial image evaluation was performed in the same manner as in Example 1 except that the bias of the power source applied to the charging roller was set to DC-1500V. As a result, it was confirmed that the images of the white background, the black background, and the gradation pattern were good, and no black spots generated due to the leakage of the current of the photoreceptor were found. Next, when a continuous test was performed, fog and density were good until about 23,000 sheets had elapsed, but black spots were observed in the gradation pattern. This black spot is considered to be the cause of current leakage due to local defects in the photoreceptor.

Example 10
On a cylindrical drum made of uncut aluminum with a diameter of 30 mm, titanium oxide particles (trade name: TTO-55, manufactured by Ishihara Sangyo Co., Ltd.) coated with alumina and coated with alumina and polyimide resin in a weight ratio of 1: A solution mixed at a rate of 5.9 was applied, and then dried at 140 ° C. for 30 minutes to form a first undercoat layer having a thickness of 40.0 μm. Next, melamine alkyd resin as a thermosetting resin and titanium oxide (trade name: CR-EL, manufactured by Ishihara Sangyo Co., Ltd.) having a particle size of 0.25 μm were dissolved in methyl ethyl ketone and applied at a ratio of 1: 3. The coating solution was applied onto the undercoat layer to form a second undercoat layer having a thickness of 1.0 μm.

  The initial image evaluation was performed in the same manner as in Example 1 except that the bias of the power source applied to the charging roller was set to DC-1500V. As a result, it was confirmed that the images of the white background, the black background, and the gradation pattern were good, and no black spots generated due to the leakage of the current of the photoreceptor were found. Next, when 30,000 continuous tests were performed, it was confirmed that the images of the white background, the black background, and the gradation pattern were satisfactory, and the same black spots as described above were not observed.

Example 11
On a cylindrical drum made of uncut aluminum with a diameter of 30 mm, titanium oxide particles (trade name: TTO-55, manufactured by Ishihara Sangyo Co., Ltd.) coated with alumina and coated with alumina and polyimide resin in a weight ratio of 1: A solution mixed at a rate of 5.9 was applied, and then dried at 140 ° C. for 30 minutes to form a first undercoat layer having a thickness of 10.0 μm. However, the second undercoat layer was not formed here.

  The initial image evaluation was performed in the same manner as in Example 1 except that the bias of the power source applied to the charging roller was set to DC-1200 V. As a result, it was confirmed that each image such as a white background, a black background, and a gradation pattern was good. Further, current leaked due to local defects in the electrophotographic photosensitive member, and black spots generated due to the leakage were not observed. Next, a continuous test of 30,000 sheets was performed, and it was confirmed that the images of the white background, the black background, the gradation pattern, and the like were also good here. However, in the white background image, there was no problem with fog, but it was determined that there was no problem in practical use. Therefore, current leaked due to local defects in the electrophotographic photosensitive member, and black spots generated due to the leakage were not observed.

Example 12
On a cylindrical drum made of uncut aluminum with a diameter of 30 mm, titanium oxide particles (trade name: TTO-55, manufactured by Ishihara Sangyo Co., Ltd.) coated with alumina and coated with alumina and polyimide resin in a weight ratio of 1: A solution mixed at a rate of 5.9 was applied, and then dried at 140 ° C. for 30 minutes to form a first undercoat layer having a thickness of 20.0 μm. However, the second undercoat layer was not formed here.

  Other than that, initial image evaluation was performed in the same manner as in Example 1. As a result, it was confirmed that each image such as a white background, a black background, and a gradation pattern was good. Further, no black spots were generated due to current leakage due to local defects in the electrophotographic photosensitive member. Next, a continuous test of 30,000 sheets was performed, and it was confirmed that the images of the white background, the black background, the gradation pattern, and the like were also good here. However, in the white background image, there was no problem with fog, but it was determined that there was no problem in practical use. Therefore, current leaked due to local defects in the electrophotographic photosensitive member, and black spots generated due to the leakage were not observed.

Comparative Example 1
Mixing titanium oxide particles (trade name: CR-EL, manufactured by Ishihara Sangyo Co., Ltd.) and polyimide resin in a weight ratio of 1: 1 on a cylindrical drum made of uncut aluminum with a diameter of 30 mm. After applying the solution, it was dried at 140 ° C. for 30 minutes to form a first undercoat layer having a thickness of 10.0 μm. Next, melamine alkyd resin as a thermosetting resin and titanium oxide (trade name: CR-EL, manufactured by Ishihara Sangyo Co., Ltd.) having a particle size of 0.25 μm were dissolved in methyl ethyl ketone and applied at a ratio of 1: 3. The coating solution was applied onto the undercoat layer to form a second undercoat layer having a thickness of 1.0 μm.

  Other than that, the initial image evaluation was performed in the same manner as in Example 1. As a result, it was confirmed that the images of the white background, black background, and gradation pattern were good, and black spots generated due to current leakage of the photoconductor. Was not seen. Next, when a continuous test was performed, fog and density were good until about 10,000 sheets were passed, but black spots were observed in the gradation pattern. This black spot is considered to be the cause of current leakage due to local defects in the photoreceptor.

Comparative Example 2
Mixing titanium oxide particles (trade name: CR-EL, manufactured by Ishihara Sangyo Co., Ltd.) and polyimide resin in a weight ratio of 1: 1 on a cylindrical drum made of uncut aluminum with a diameter of 30 mm. After applying the solution, it was dried at 140 ° C. for 30 minutes to form a first undercoat layer having a thickness of 10.0 μm. Next, melamine alkyd resin as a thermosetting resin and titanium oxide (trade name: CR-EL, manufactured by Ishihara Sangyo Co., Ltd.) having a particle size of 0.25 μm were dissolved in methyl ethyl ketone and applied at a ratio of 1: 3. The coating solution was applied onto the undercoat layer to form a second undercoat layer having a thickness of 1.0 μm.

  The initial image evaluation was performed in the same manner as in Example 1 except that the bias of the power source applied to the charging roller was set to DC-1500V. As a result, it was confirmed that the images of the white background, the black background, and the gradation pattern were good, and no black spots generated due to the leakage of the current of the photoreceptor were found. Next, when a continuous test was performed, fog and density were good until about 7,500 sheets were passed, but black spots were observed in the gradation pattern. This black spot is considered to be the cause of current leakage due to local defects in the photoreceptor.

Comparative Example 3
A cylindrical drum made of uncut aluminum with a diameter of 30 mm was prepared, and washed with a weak alkaline cleaning solution instead of forming the first undercoat layer, and the second undercoat layer and the charge generation layer were the same as in Example 1. The charge transfer layer was sequentially provided. Next, a charging roller similar to that in Example 1 was produced. As in Example 1, the initial image was evaluated. As a result, the fog, density, etc. were good. However, in the gradation pattern, the black color generated due to the current leak caused by the local defect of the photoreceptor was observed. It was. The continuous test was not performed because current leakage occurred in the initial stage.

Comparative Example 4
A cylindrical drum made of uncut aluminum having a diameter of 30 mm was prepared, and instead of forming the first undercoat layer, it was washed with a weak alkaline cleaning solution, and then the second undercoat layer was formed. The second undercoat layer is a ratio of 1: 3 of polyamide resin (alcohol-soluble nylon resin: trade name CM4000) and titanium oxide (trade name: CR-EL, manufactured by Ishihara Sangyo Co., Ltd.) having a particle size of 0.25 μm. Then, this was dissolved and dispersed in a mixed solution of methanol and chloroform to obtain an undercoat layer coating solution. Next, the cylindrical drum was dip-coated in this undercoat layer coating solution, and then dried at 120 ° C. for 20 minutes to form a 3.0 μm undercoat layer. A charge generation layer and a charge transfer layer were sequentially provided on the undercoat layer in the same manner as in Example 1.

  Next, an initial image was evaluated in the same manner as in Example 1 except that a charging roller similar to that in Example 1 was prepared and the bias of the power source applied to the charging roller was set to DC-1200V. As a result, it was confirmed that the images of the white background, the black background, and the gradation pattern were good, and no black spots generated due to the leakage of the current of the photoreceptor were found. Next, when a continuous test was performed, fog and density were good until about 5,500 sheets had elapsed, but black spots were observed in the gradation pattern. This black spot is considered to be the cause of current leakage due to local defects in the photoreceptor.

Comparative Example 5
Titanium oxide particles (trade name: TTO-55, manufactured by Ishihara Sangyo Co., Ltd.) coated with alumina on a cylindrical drum made of uncut aluminum with a diameter of 30 mm and polyamide resin (alcohol-soluble nylon resin: (Trade name CM4000) was mixed at a weight ratio of 1: 5.9, and the mixed solution was dissolved and dispersed in a mixed solution of methanol and chloroform to prepare an undercoat layer coating solution. Next, the cylindrical drum was dip-coated in this undercoat layer coating solution, and then dried at 120 ° C. for 20 minutes to form an undercoat layer having a thickness of 20 μm. Next, melamine alkyd resin as a thermosetting resin and titanium oxide (trade name: CR-EL, manufactured by Ishihara Sangyo Co., Ltd.) having a particle size of 0.25 μm were dissolved in methyl ethyl ketone and applied at a ratio of 1: 3. The coating solution was applied onto the undercoat layer to form a second undercoat layer having a thickness of 1.0 μm.

  Other than that, the initial image evaluation was performed in the same manner as in Example 1. As a result, it was confirmed that the images of the white background, the black background, and the gradation pattern were satisfactory, and the black spots generated due to the current leakage of the photoconductor. Was not seen. Next, when a continuous test was performed, fogging occurred in the white background image when about 12,000 sheets had passed. However, generation of black spots and white spots in white background, black background, and gradation pattern was not observed. Furthermore, when the continuous test was continued, the fog was worsened in the white background image at the time of about 30,000 sheets. However, generation of black spots and white spots in white background, black background, and gradation pattern was not observed.

  Table 1 shows the above examples and comparative examples.

1 is a schematic view showing an electrophotographic apparatus using an electrophotographic photosensitive member according to the present invention. In the present invention, it is a graph showing the relationship between the thickness of the undercoat layer and the leakage generation voltage.

Explanation of symbols

DESCRIPTION OF SYMBOLS 21 Photosensitive drum 22 Charging roller 23 Laser beam irradiation apparatus 24 Developing roller 25 Developing roller blade 26 Supply roller 27 Casing 28 Toner 29 Developing apparatus 210 Transfer roller 211 Transfer material 212 Cleaning blade 213 Fixing roller 214 Pressure roller

Claims (7)

In an electrophotographic photoreceptor in which a photosensitive layer is formed on a conductive substrate via an undercoat layer,
An electrophotographic photoreceptor, wherein the undercoat layer is formed to a thickness of 10 μm or more, and a white pigment containing a metal oxide having an average particle size of 0.18 μm or less is dispersed in the undercoat layer. .   The undercoat layer has a two-layer structure of a first undercoat layer and a second undercoat layer, the first undercoat layer is formed to a thickness of 10 μm or more, and the first undercoat layer The electrophotographic photosensitive member according to claim 1, wherein a white pigment containing a metal oxide having an average particle size of 0.18 μm or less is dispersed.   The electrophotographic photosensitive member according to claim 1, wherein the undercoat layer contains a polyimide resin.   The electrophotographic photosensitive member according to claim 1, wherein the white pigment is titanium oxide.   The electrophotographic photosensitive member according to claim 1, wherein the photosensitive layer has a thickness of 20 μm or less.   An electrophotographic apparatus, wherein a voltage of 1500 V or less in absolute value is applied to the electrophotographic photosensitive member according to claim 1. The electrophotographic apparatus according to claim 6, wherein a contact charging system that directly contacts the photographic photosensitive member is used.

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