JP2007148294A - Electrophotographic photoreceptor, process cartridge, and electrophotographic apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrophotographic photoreceptor which achieves the most strict reduction level of ghost images that has ever existed, and also to provide a process cartridge and an electrophotographic apparatus equipped each equipped with the electrophotographic photoreceptor. <P>SOLUTION: The electrophotographic photoreceptor has an intermediate layer containing an electron transport compound, a charge generating layer, and a hole transport layer containing a hole transport material in this order on a conductive support, wherein the intermediate layer is formed from a coating liquid for an intermediate layer containing: a thermoplastic resin containing a unit having an alkylene backbone and a hydroxyaryl group in a side chain; and the electron transport compound. The process cartridge and the electrophotographic apparatus each equipped with the electrophotographic photoreceptor are also provided. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an electrophotographic photosensitive member, a process cartridge, and an electrophotographic apparatus, and more specifically, an electrophotographic photosensitive member having a specific thermoplastic resin and an electron transport compound in an intermediate layer, a process cartridge and an electronic device including the electrophotographic photosensitive member. The present invention relates to a photographic apparatus.

  Conventionally, as an electrophotographic photoreceptor, inorganic photoreceptors mainly composed of an inorganic photoconductive compound such as selenium, zinc oxide and cadmium sulfide have been widely used. In recent years, as seen in Patent Documents 1 to 5 and the like, the two functions of a hole transport layer (charge transport layer) and a charge generation layer in which an organic photoconductive substance is bound with a resin or the like are separated. Various proposals have been made regarding laminated organic electrophotographic photoreceptors having layers. In particular, an electrophotographic photosensitive member having a layer structure in which a charge transport layer is provided on a charge generation layer is excellent in durability and is currently mainstream. For example, Patent Document 6 discloses a photoreceptor having a charge transfer layer containing triallylpyrazoline, Patent Document 7 discloses a charge generation layer formed of a derivative of perylene pigment, and a charge transfer layer formed of a condensate of 3-propylene and formaldehyde. A photoconductor and the like are disclosed. Further, as an electrophotographic photoreceptor using a disazo pigment or a trisazo pigment as a charge generating substance, there are Patent Document 8 and Patent Document 9. Further, the organic photoconductive compound can freely select the photosensitive wavelength range of the electrophotographic photosensitive member depending on the compound. For example, with regard to azo-based organic pigments, the substances disclosed in Patent Document 10 and Patent Document 11 are those that exhibit high sensitivity in the visible region, and the substances disclosed in Patent Document 12 and Patent Document 13 Some have sensitivity even in the infrared region.

  Of these charge generation materials, charge generation materials having sensitivity in the red or infrared region are used in laser beam printers, LED printers, and the like that have made remarkable progress in recent years. Conventionally, copper phthalocyanine (Patent Document 14), metal-free phthalocyanine, and the like are listed as charge generating substances having sensitivity in the infrared region, but they are insufficient for increasing the sensitivity today. Further, in Patent Document 15 and the like, it has been proposed to increase sensitivity by adding an organic acceptor to the charge generation layer in the laminated organic electrophotographic photosensitive member, but this is not sufficient. Oxytitanium phthalocyanine pigments (Patent Literature 16 and Patent Literature 17), gallium phthalocyanine pigments (Patent Literature 18 and Patent Literature 19) and chlorogallium phthalocyanine pigments (Patent Literature 20 and Patent Literature 21) as charge generation materials that can cope with high sensitivity in recent years. ) Etc. are attracting attention.

  However, the development of today's electrophotographic technology is remarkable, and very advanced technology is required for the characteristics required for electrophotographic photoreceptors. For example, the process speed is increasing year by year, and charging characteristics, sensitivity, durability stability, and the like have been demanded. In particular, in recent years, high-quality images have been screamed as typified by colorization, and black-and-white images that have been character-centered have become more and more halftone images and solid images typified by photographs. Their image quality is increasing year by year. In particular, a phenomenon in which the light-irradiated portion of one image is darkened only in the light-irradiated portion in the halftone image at the next rotation, a so-called positive ghost image, on the contrary, the density of the portion is lightened. The permissible range for so-called negative ghosts and the like has become much stricter than the permissible range for black and white printers and black and white copiers. These ghost images use a highly sensitive charge generation material, so that the absolute number of carriers is large, and electrons after holes are injected into the hole transport layer are likely to remain in the charge generation layer, resulting in a memory. This is considered to be a remarkable phenomenon particularly when used as a highly sensitive charge generating material such as gallium phthalocyanine.

  On the other hand, cost reduction and miniaturization are evolving year by year, and there is an increasing demand for less technology such as cleaner-less and pre-exposure-less. In particular, with regard to pre-exposure, black and white laser printers and black-and-white copiers are often not already installed, and it is easy to increase the number of color printers and color copiers that do not have pre-exposure. It can be imagined. Therefore, the level of the ghost image in the color machine without pre-exposure needs to be several levels higher than the level allowed by the black and white printer or black and white copier.

  Examples of proposals for reducing ghosts include an example in which polycyclic quinone and perylene are contained in the intermediate layer (Patent Document 22), an example using a metallocene compound and an electron-withdrawing compound, a melamine resin (Patent Document 23), and metal oxide fine particles And an example using a silane coupling agent (Patent Document 24), an example using metal oxide fine particles surface-treated with a silane coupling agent (Patent Document 25), etc. It was not effective for severe ghost levels. In addition, an example in which vinylphenol is used for the intermediate layer to prevent black spots, fog, etc. (Patent Document 26), an example in which surface defects on the substrate and potential decrease are suppressed (Patent Document 27), etc. are disclosed. The above ghost level was not effective.

  Further, the ghost phenomenon is particularly likely to occur in a photoconductor using an intermediate layer as compared with a case where a photosensitive layer is formed directly on a conductive substrate. In other words, it is considered that the intermediate layer used for preventing the deterioration of the characteristics of the photosensitive member due to the defect of the substrate, the white spot and the black spot causes an image defect called a new ghost.

As described above, there is a demand for an electrophotographic photosensitive member that satisfies the severe ghost level in printers and copying machines without pre-exposure, particularly color machines.
JP-A-57-54942 JP 60-59355 A JP-A-61-203461 JP-A 62-47054 JP-A 62-67094 U.S. Pat. No. 3,378,851 U.S. Pat. No. 3,871,882 JP 56-46237 A JP-A-60-111249 JP 60-272754 A JP 56-167759 A JP-A-57-195767 Japanese Patent Laid-Open No. 61-228453 Japanese Patent Laid-Open No. 50-38543 JP-A-61-2157 JP-A-63-366 JP-A-1-319934 JP-A-5-249716 Japanese Patent Laid-Open No. 5-263007 JP-A-5-188615 JP-A-5-194523 Japanese Patent Application Laid-Open No. 8-14639 Japanese Patent Laid-Open No. 10-73942 JP-A-8-22136 JP 9-258469 A JP-A-1-169473 JP-A-2-256060

  An object of the present invention has been made in view of the above circumstances, and provides an electrophotographic photosensitive member that achieves an unprecedented level of ghost images, a process cartridge including the electrophotographic photosensitive member, and an electrophotographic apparatus. It is to be.

  According to the present invention, there is provided a laminated electrophotographic photoreceptor having, in this order, an intermediate layer containing an electron transport compound, a charge generation layer, and a hole transport layer containing a hole transport material on a conductive support, An electrophotographic photoreceptor characterized in that it is formed from an intermediate layer coating solution containing a thermoplastic resin containing a unit unit having an alkylene main chain and a hydroxyaryl group as a side chain and an electron transport compound is provided.

  In addition, according to the present invention, a process cartridge and an electrophotographic apparatus provided with the electrophotographic photosensitive member are provided.

  According to the present invention, it is possible to provide an electrophotographic photosensitive member that achieves an unprecedented level of ghost images, a process cartridge and an electrophotographic apparatus including the electrophotographic photosensitive member.

  Hereinafter, the electrophotographic photoreceptor of the present invention will be described in detail.

  As the conductive support used in the present invention, a metal or alloy such as aluminum, nickel, copper, gold or iron, a metal such as aluminum, silver or gold on an insulating support such as polyester, polycarbonate, polyimide or glass. Or what formed the thin film of electroconductive materials, such as an indium oxide and a tin oxide, what disperse | distributed carbon and the electroconductive filler in resin, and gave the electroconductivity etc. can be illustrated. The surface of these supports is a support that has been subjected to an electrochemical treatment such as anodization to improve electrical properties or adhesion, and the surface of a conductive support is alkali phosphate, phosphoric acid or tannin. It is also possible to use a solution obtained by chemical treatment with a solution obtained by dissolving a metal salt compound or a fluorine compound metal salt in an acidic aqueous solution containing an acid as a main component.

  In addition, when the electrophotographic photosensitive member is used in a printer using a single wavelength laser beam or the like, the surface of the conductive support needs to be appropriately roughened in order to suppress interference fringes. is there. Specifically, a support having a surface treated with honing, blasting, cutting, electropolishing, or the like, or a support having a conductive film made of a conductive metal oxide and a binder resin on aluminum and an aluminum alloy. Must be used.

  As the honing treatment, there are dry and wet treatment methods, and any of them may be used. The wet honing treatment is a method in which a powdery abrasive is suspended in a liquid such as water and sprayed onto the surface of the support at a high speed to roughen the surface. The surface roughness is the spray pressure, speed, and amount of abrasive. It can be controlled by the type, shape, size, hardness, specific gravity, suspension temperature and the like. Similarly, the dry honing process is a method in which an abrasive is sprayed onto the surface of the conductive support with air at a high speed to roughen the surface, and the surface roughness can be controlled in the same manner as the wet honing process. Examples of the abrasive used for the wet or dry honing treatment include particles such as silicon carbide, alumina, iron, and glass beads.

In a method in which a conductive film made of a conductive metal oxide and a binder resin is applied to a support of aluminum or aluminum alloy to form a conductive support, a powder made of conductive fine particles is used as a filler in the conductive film. Containing. This method has the effect of dispersing the fine particles in the film to diffusely reflect the laser beam to prevent interference fringes and conceal the scratches and protrusions of the support before coating. Titanium oxide, barium sulfate, or the like is used for the fine particles. If necessary, a conductive coating layer is provided on the fine particles with tin oxide or the like, so that a specific resistance suitable as a filler is obtained. The specific resistance of the conductive fine particle powder is preferably 0.1 to 1000 Ω · cm, more preferably 1 to 1000 Ω · cm. The specific resistance of the powder was measured using a resistance measuring device Loresta AP (Loresta Ap) manufactured by Mitsubishi Chemical Corporation. The powder to be measured was hardened at a pressure of 500 kg / cm ² and attached to the measuring device as a coin sample. The average particle size of the fine particles is preferably 0.05 to 1.0 μm, more preferably 0.07 to 0.7 μm. The average particle diameter of the fine particles is a value measured by a centrifugal sedimentation method. The content of the filler is preferably 1.0 to 90% by mass, and more preferably 5.0 to 80% by mass with respect to the conductive film layer. The coating layer may contain fluorine or antimony as necessary.

  As the binder resin used for the conductive film, for example, phenol resin, polyurethane, polyamide, polyimide, polyamideimide, polyamic acid, polyvinyl acetal, epoxy resin, acrylic resin, melamine resin, or polyester is preferable. These resins may be used alone or in combination of two or more. These resins have good adhesion to the support, improve the dispersibility of the filler used, and have good solvent resistance after film formation. Among the above resins, phenol resin, polyurethane and polyamic acid are particularly preferable.

The conductive film can be formed, for example, by dipping or solvent application with a Meyer bar or the like. The thickness of the conductive film is preferably from 0.1 to 30 μm, more preferably from 0.5 to 20 μm. The volume resistivity of the conductive film is preferably 10 ¹³ Ω · cm or less, more preferably 10 ¹² Ω · cm or less and 10 ⁵ Ω · cm or more. In the present invention, the volume resistivity is obtained by applying a conductive film to be measured on an aluminum plate, further forming a gold thin film on the film, and calculating the current value flowing between both electrodes of the aluminum plate and the gold thin film as pA. It was determined by measuring with a meter. The conductive film may contain a filler made of powder such as zinc oxide or titanium oxide in addition to the powder made of barium sulfate fine particles having a coating layer. Furthermore, a leveling agent may be added to enhance the surface property.

  The shape of the conductive support is not particularly limited, and a plate, drum, or belt is used as necessary.

  The intermediate layer used in the present invention is formed from an intermediate layer coating solution containing an electron transport compound and a thermoplastic resin containing a unit unit having at least an alkylene main chain and a hydroxyaryl group in the side chain. The electron transport compound is one in which reduction and oxidation peaks are observed in the reduction potential measurement of cyclic voltammetry, and more preferably, both peak current values are equivalent. The electron transport compound is particularly preferably a compound having a structure represented by the following formulas (1) to (4).

Wherein indicates the X ₁ to X ₄ each independently represent a hydrogen atom, a halogen group, a nitro group, which may have a an optionally substituted alkoxy group or an optionally substituted alkyl group. R ₁ and R ₂ are each independently an alkyl group which may be interrupted by an ether group, an alkenyl group which may be interrupted by an ether group, a heterocyclic group; an alkyl group, an alkenyl group, a nitro group, a halogen group, halogen Substituted with an aryl group or alkyl group which may have a substituted alkyl group, an alkenyl group, a nitro group, a halogen group, an aralkyl group which may have a halogen-substituted alkyl group, a carbonyl group substituted with an alkyl group, or an alkyl group Represents a substituted sulfonyl group.

In the formula, Z ₁ and Z ₂ each independently represent oxygen, C (CN) ₂ group or N—R (R represents an aryl group or alkyl group which may have a substituent). X _{11 to} X ₁₈ may each independently have a hydrogen atom, a hydroxyl group, a halogen atom, a nitro group, a trifluoroalkyl group, a carboxyl group, an amino group, an alkoxy group that may have a substituent, or a substituent. An alkyl group, an optionally substituted carbonyl group, an optionally substituted ester group or an optionally substituted aryl group is shown.

In the formula, Z ₁₁ and Z ₁₂ each independently represent oxygen, C (CN) ₂ group or N—R (R represents an aryl group or alkyl group which may have a substituent). X _{21 to} X ₂₆ each independently have a hydrogen atom, a hydroxyl group, a halogen atom, a nitro group, a trifluoroalkyl group, a carboxyl group, an amino group, an alkoxy group that may have a substituent, or a substituent. An alkyl group, an optionally substituted carbonyl group, an optionally substituted ester group or an optionally substituted aryl group is shown.

In the formula, Z ₂₁ and Z ₂₂ each independently represent oxygen, C (CN) ₂ group or N—R (R represents an aryl group or alkyl group which may have a substituent). X _{31 to} X ₃₆ each independently have a hydrogen atom, a hydroxyl group, a halogen atom, a nitro group, a trifluoroalkyl group, a carboxyl group, an amino group, an alkoxy group that may have a substituent, or a substituent. An alkyl group, an optionally substituted carbonyl group, an optionally substituted ester group or an optionally substituted aryl group is shown.

  The thermoplastic resin that forms the intermediate layer together with the electron transport compound is a thermoplastic resin containing a unit structure having an alkylene main chain and a hydroxyaryl group in the side chain represented by the following formula (5). It may be a homopolymer or a copolymer with other known vinyl monomers.

In formula, R < ₃ > -R < ₅ > shows a hydrogen atom, a halogen group, a nitro group, the alkoxy group which may have a substituent, the alkyl group which may have a substituent, or an aryl group each independently. R ₆ is independently an alkyl group which may be interrupted by an ether group, an alkenyl group which may be interrupted by an ether group, a heterocyclic group; an alkyl group, an alkenyl group, a nitro group, a halogen group, a halogen-substituted alkyl group Represents an aralkyl group which may have an aryl group or an alkyl group, an alkenyl group, a nitro group, a halogen group or a halogen-substituted alkyl group, which may have an alkyl group, and preferably has 0 to 20 carbon atoms. In the case of 0 carbon atoms, the aryl group A shown below is bonded to the alkylene main chain. A represents an aromatic hydrocarbon such as a phenylene group, a naphthylene group, an anthrylene group or a phenanthrylene group which may have a substituent. m is an integer of 1 or more.

  The aryl group of the hydroxyaryl group is preferably a phenyl group.

  Further, when an isocyanate compound is further contained in addition to the above, a more preferable ghost image reduction effect can be obtained. Although details are unknown, it is thought that the presence of the electron transport compound changes due to a partial crosslinking reaction with the hydroxyaryl group-containing resin during the formation of the intermediate layer.

  Isocyanate compounds include aromatic isocyanate compounds such as tolylene diisocyanate, metaxylylene diisocyanate, diphenylmethane diisocyanate, and polymethylene polyphenylene isocyanate; hydrogenated products of the above isocyanates, aliphatic isocyanate compounds such as hexamethylene diisocyanate; and these isocyanate compounds. And a blocked isocyanate compound in which the isocyanate group is blocked with phenol, ketoxime, aromatic secondary amine, tertiary alcohol, amide, lactam, heterocyclic compound, sulfite or the like. Moreover, the said isocyanate compound can also be used with the form of a dimer-a pentamer.

  The electron transport compound represented by the formulas (1) to (4) is preferably 5 to 95% by mass, more preferably 25 to 80% by mass, and still more preferably 31 to 70% by mass with respect to the entire intermediate layer. is there.

  The compound to be added is effective in any structure, but a compound having a reduction potential of −0.25 to −0.65 V (vs. SCE) is more preferable. The reduction potential was performed in acetonitrile at a sweep rate of 50 mV / s using tetrabutylammonium perchlorate and a platinum electrode as the supporting electrolyte. The above-mentioned material is dissolved and applied in a suitable solvent, and the thickness of the intermediate layer is preferably 0.05 to 5 μm, particularly 0.3 to 3 μm.

  Next, examples of the electron transport compounds represented by the general formulas (1) to (4) are listed in the following Tables 1 to 4, but are not limited thereto.

  Examples of the charge generating material used in the present invention include pyrylium dyes, thiopyrylium dyes, phthalocyanine pigments, anthanthrone pigments, dibenzpyrenequinone pigments, pyratron pigments, azo pigments, indigo pigments, quinacridone pigments, and And quinocyanine dyes. Examples of the phthalocyanine compound include metal-free phthalocyanine, oxytitanium phthalocyanine, hydroxyphthalocyanine, and gallium halide phthalocyanine such as chlorogallium. Although details are not clear, in the present invention, when gallium phthalocyanine, particularly hydroxygallium phthalocyanine is used, a particularly preferable ghost suppressing effect is obtained.

  The charge generation layer may contain a charge generation material other than the phthalocyanine compound up to 50 mass% with respect to the total charge generation material. Examples thereof include selenium-tellurium, pyrylium, thiapyrylium dyes, anthanthrone, dibenzpyrenequinone, trisazo, cyanine, disazo, monoazo, indigo, quinacridone, and asymmetric quinocyanine pigments.

  The charge generation layer is a homogenizer, ultrasonic dispersion, ball mill, vibration ball mill, sand mill, attritor, roll mill, or liquid collision type high-speed disperser together with the charge generation material in a mass ratio of 0.3 to 4 times the binder resin and solvent. And the like, and then a solution obtained by adding an electron transporting compound to the dispersion is applied and dried.

  As binder resin, butyral resin, polyester resin, polycarbonate resin, polyarylate resin, polystyrene resin, polyvinyl methacrylate resin, polyvinyl acrylate resin, polyvinyl acetate resin, polyvinyl chloride resin, polyamide resin, polyurethane resin, silicone resin, alkyd resin , Epoxy resin, cellulose resin, melamine resin, and the like, but are not limited thereto. In particular, a butyral resin is preferred. The thickness of the charge generation layer is preferably 5 μm or less, particularly preferably 0.1 to 2 μm.

  A hole transport layer is formed on the charge generation layer. The hole transport layer is formed by applying and drying a paint in which a hole transport material and a binder resin are dissolved in a solvent. Examples of the hole transport material used include triarylamine compounds, hydrazone compounds, stilbene compounds, pyrazoline compounds, oxazole compounds, triallylmethane compounds, and thiazole compounds.

  Examples of the binder resin include polyester resin, polycarbonate resin, polyarylate resin, polystyrene resin, polyvinyl methacrylate resin, polyvinyl acrylate resin, polyamide resin, polyurethane resin, silicone resin, alkyd resin, epoxy resin, cellulose resin, and melamine resin. However, a particularly preferable ghost suppression effect was obtained when a polyarylate resin having a structural unit represented by the following formula (6) was used.

  The polyarylate resin having a structural unit represented by the following formula (6) may be used alone or as a resin such as polycarbonate resin, polyester resin, polymethacrylic ester, polystyrene resin, acrylic resin, polyamide resin, poly-N-vinylcarbazole, It is preferable to use a mixture with an organic photoconductive polymer such as polyvinyl anthracene.

In the formula, X ⁴⁰ represents a carbon atom or a single bond (in this case, R ¹⁵ and R ¹⁶ are absent), and R ^{11 to} R ¹⁴ represent a hydrogen atom, a halogen atom, an optionally substituted alkyl group or an aryl group. , R ¹⁵ and R ¹⁶ represent a hydrogen atom, a halogen atom, an optionally substituted alkyl group, an aryl group, or an alkylidene group formed by combining R ¹⁵ and R ¹⁶ , and R ^{17 to} R ²⁰ represent a hydrogen atom. , A halogen atom, an optionally substituted alkyl group or an aryl group.

  The weight average molecular weight of the binder resin is preferably 50,000 to 200,000, and more preferably 100,000 to 180,000. The weight average molecular weight was determined by measuring the molecular weight distribution using gel permeation chromatography (“HLC-8120” manufactured by Tosoh Corporation) and calculating the polystyrene equivalent.

For the measurement, tetrahydrofuran (THF) was used as a developing solvent, and a 0.1 mass% solution of a resin sample was used as a column with an exclusion limit molecular weight (polystyrene conversion) 4 × 10 ⁶ column (“TSKgel SuperHM-N” manufactured by Tosoh Corporation). ”), Using RI as a detector, under conditions of a column temperature of 40 ° C., an injection amount of 20 μl, and a flow rate of 1.0 ml / min.

  The hole transport material is combined with a binder resin in an amount of 0.5 to 2 times by mass, and applied and dried to form a hole transport layer. The film thickness of the hole transport layer is preferably 5 to 30 μm, more preferably 8 to 19 μm.

  In addition to the hole transport layer, antioxidants such as hindered phenols and hindered amines, lubricating materials such as silicone oil, silicone oil particles and fluorine atom-containing resin particles, and film strength reinforcing materials such as silicone balls. It may be added. A coating liquid containing these is applied onto the charge generation layer and dried to obtain a hole transport layer.

  In the present invention, a protective layer may be provided on the hole transport layer. The material constituting the protective layer is polyester, polyacrylate, polyethylene, polystyrene, polybutadiene, polycarbonate, polyamide, polypropylene, polyimide, polyamideimide, polysulfone, polyacryl ether, polyacetal, phenol, acrylic, silicone, epoxy, urea, allyl. Alkyd, butyral, phenoxy, phosphazene, acrylic-modified epoxy, acrylic-modified urethane, and acrylic-modified polyester resin. The thickness of the protective layer is preferably 0.2 to 10 μm.

  Each of the above layers has a polytetrafluoroethylene, polyvinylidene fluoride, a fluorine-based graft polymer, a silicone-based graft polymer, a fluorine-based block polymer, a silicone-based block polymer, and a silicone for improving cleaning properties and abrasion resistance. You may contain lubricants, such as system oil. Furthermore, an additive such as an antioxidant may be added for the purpose of improving the weather resistance.

  Further, conductive powder such as conductive tin oxide and conductive titanium oxide may be dispersed in the protective layer for the purpose of resistance control.

  FIG. 1 shows a schematic configuration of an electrophotographic apparatus provided with a process cartridge having the electrophotographic photosensitive member of the present invention.

  In FIG. 1, reference numeral 1 denotes a drum-shaped electrophotographic photosensitive member of the present invention, which is rotationally driven around a shaft 2 in a direction indicated by an arrow with a predetermined peripheral speed (process speed). In the rotation process, the electrophotographic photosensitive member 1 is subjected to uniform charging at a predetermined positive or negative potential on its peripheral surface by the primary charging unit 3, and then, for example, slit exposure or laser beam scanning exposure that is reflected light from the original. The exposure light 4 intensity-modulated in response to the time-series electric digital image signal of the target image information output from the exposure means (not shown) is received. In this way, electrostatic latent images corresponding to the target image information are sequentially formed on the peripheral surface of the electrophotographic photoreceptor 1.

  The formed electrostatic latent image is visualized as a transferable particle image (toner image) by regular development or reversal development with charged particles (toner) in the developing means 5 and is electrophotographic from a paper supply unit (not shown). A toner image formed and carried on the surface of the electrophotographic photosensitive member 1 is transferred to the transfer material 7 which is taken out and fed between the photosensitive member 1 and the transfer unit 6 in synchronization with the rotation of the electrophotographic photosensitive member 1. The images are sequentially transferred by the transfer means 6. At this time, a bias voltage having a polarity opposite to the charge held in the toner is applied to the transfer means from a bias power source (not shown).

  The transfer material 7 (in the case of a final transfer material (such as paper or film)) that has received the transfer of the toner image is separated from the electrophotographic photosensitive member surface, conveyed to the image fixing means 8, and subjected to a toner image fixing process. Printed out of the apparatus as an image formed product (print, copy). When the transfer material 7 is a primary transfer material (intermediate transfer material or the like), it is printed out after a fixing process after a plurality of transfer processes.

  The surface of the electrophotographic photosensitive member 1 after the transfer of the toner image is cleaned by removing the deposits such as residual toner by the cleaning means 9. In recent years, a cleanerless system has been studied, and the transfer residual toner can be directly collected by a developing device or the like.

  The primary charging unit 3 may be a scorotron charger or a corotron charger using corona discharge, or a contact type charger using a known form such as a roller shape, a blade shape, or a brush shape. As a material of the member of the contact charger, an elastic body imparted with conductivity is generally used. The voltage applied to the contact charging member may be only a DC voltage or an oscillating voltage obtained by superimposing an AC voltage on a DC voltage. The oscillating voltage referred to here is a voltage whose voltage value periodically changes with time, and the AC voltage has a peak-to-peak voltage that is at least twice the charging start voltage of the photosensitive member when only the DC voltage is applied. preferable.

  In the present invention, among the above-described components such as the electrophotographic photosensitive member 1, the primary charging unit 3, the developing unit 5 and the cleaning unit 9, a plurality of components are housed in a container and integrally combined as a process cartridge. The process cartridge may be configured to be detachable from an electrophotographic apparatus main body such as a copying machine or a laser beam printer. For example, at least one of the primary charging unit 3, the developing unit 5, and the cleaning unit 9 is integrally supported together with the electrophotographic photosensitive member 1 to form a cartridge, and is attached to and detached from the apparatus main body using the guide unit 12 such as a rail of the apparatus main body. A flexible process cartridge 11 can be obtained.

  Further, when the electrophotographic apparatus is a copying machine or a printer, the exposure light 4 is reflected or transmitted light from the original, or the original is read by a sensor and converted into a signal, and a laser beam scanning performed according to this signal is performed. The light emitted by driving the LED array or the liquid crystal shutter array.

  The electrophotographic photosensitive member of the present invention can be applied not only to electrophotographic copying machines but also to general electrophotographic apparatuses such as laser beam printers, LED printers, FAX, liquid crystal shutter printers, etc. It can be widely applied to apparatuses such as applied displays, recording, light printing, plate making and facsimile.

  First, an example of production of hydroxygallium phthalocyanine used in the present invention will be shown.

<Production Example 1>
After reacting 73 g of o-phthalodinitrile, 25 g of gallium trichloride and 400 ml of α-chloronaphthalene at 200 ° C. for 4 hours in a nitrogen atmosphere, the product was filtered at 130 ° C. The obtained product was dispersed and washed at 130 ° C. for 1 hour using N, N-dimethylformamide, filtered, washed with methanol and dried to obtain 45 g of chlorogallium phthalocyanine.

  15 g of the chlorogallium phthalocyanine obtained here was dissolved in 450 g of concentrated sulfuric acid at 10 ° C., dropped into 2300 g of ice water with stirring, reprecipitated and filtered. After being dispersed and washed with 2% aqueous ammonia and sufficiently washed with ion-exchanged water, it was filtered and dried to obtain 13 g of hydroxygallium phthalocyanine. In the pigmenting step, 10 g of the obtained hydroxygallium phthalocyanine and 300 g of N, N′-dimethylformamide were milled together with 450 g of 1 mmφ glass beads at room temperature (22 ° C.) for 6 hours.

  The solid was taken out from this dispersion, washed thoroughly with methanol and then with water, and dried to obtain 9.2 g of hydroxygallium phthalocyanine crystals. This hydroxygallium phthalocyanine had strong peaks at 7.4 ° and 28.2 ° of the Bragg angle (2θ ± 0.2 °) in CuKα characteristic X-ray diffraction.

  EXAMPLES Next, although an Example demonstrates this invention concretely, this invention is not limited by these Examples. In addition, "part" in an Example represents a mass part.

Example 1
A 3003 outer diameter φ30.5 mm, inner diameter φ28.5 mm, length 260.5 mm aluminum base pipe (ED pipe) obtained by hot extrusion was prepared.

  120 parts of powder composed of fine particles of barium sulfate having a coating layer formed of tin oxide (coverage: 50 mass%, powder specific resistance: 700 Ω · cm) and resol type phenol resin (trade name: Bryofen J-325, large A solution consisting of 70 parts of Nippon Ink Chemical Co., Ltd. (solid content 70%) and 100 parts of 2-methoxy-1-propanol is dispersed with a ball mill for about 20 hours to prepare a coating solution for conductive particle resin dispersion layer. (The average particle size of the filler contained in this coating solution was 0.22 μm). This solution is applied onto an aluminum cylinder having an outer diameter of 29.92 mm, an inner diameter of 28.5 mm, and a length of 260 mm by a dip coating method, followed by heat curing at 140 ° C. for 30 minutes, thereby dispersing conductive particle resin having a thickness of 15 μm. A layer was formed and used as a conductive support.

  1 part of Exemplified Compound E1-8 in Table 1 and 9 parts of poly (p-hydroxystyrene) (trade name: Marcalinker, manufactured by Maruzen Petrochemical Co., Ltd.) on the conductive support are 150 parts of DMF and 100 parts of methanol. The solution dissolved in was applied by dip coating and dried at 90 ° C. for 5 minutes to form an intermediate layer having a thickness of 0.4 μm.

  Next, 350 parts of cyclohexanone is added to 20 parts of a hydroxygallium phthalocyanine crystal synthesized according to Production Example 1 as a charge generation material and 10 parts of polyvinyl butyral resin (trade name: BX-1, manufactured by Sekisui Chemical Co., Ltd.), and 1 mmφ glass beads The mixture was dispersed for 3 hours with a sand mill using 1, and diluted with 1200 parts of ethyl acetate. At this time, the dispersed particle diameter of the charge generation material CAPA-700 (manufactured by Horiba, Ltd.) was 0.15 μm. On the intermediate layer, this charge generation layer coating solution was applied by dip coating and dried at 100 ° C. for 10 minutes to form a charge generation layer having a thickness of 0.2 μm.

  Next, 7 parts of the compound represented by the following structural formula (7), 1 part of the compound represented by the formula (8),

And 10 parts of bisphenol C type polyarylate resin (Mw110000) having the structural unit represented by the formula (9) was dissolved in a mixed solvent in 50 parts of monochlorobenzene / 10 parts of dichloromethane to prepare a coating material for a hole transport layer. This paint was applied onto the charge generation layer by a dip coating method and dried at 110 ° C. for 1 hour to form a hole transport layer having a thickness of 18 μm. Thus, an electrophotographic photosensitive member was produced.

  As an evaluation method, the produced electrophotographic photosensitive member is a color laser printer manufactured by Hewlett-Packard Co., Ltd., laser jet 4600 remodeling machine (primary charging: roller contact DC charging, dark part potential -500 V, process speed 100 mm / second, laser The ghost image was evaluated immediately after 1000 sheets of continuous durability in a 4% image density image in an environment of 15 ° C./10% RH with the pre-exposure removed. The ghost image is produced in a single color of magenta, cyan, yellow, and black. For example, in the case of black, as shown in FIG. A halftone image was prepared. The order of image production is to take a solid white image as the first image, then take five consecutive ghost images, then take one solid black image and then take five ghost images again for a total of ten images. Evaluation was performed using a ghost image. The evaluation of the ghost image is carried out by measuring the density difference between the Keima pattern image density and the image density of the ghost part with a spectral densitometer X-Rite 504/508 (manufactured by X-Rite Co., Ltd.) at 10 points with one ghost image. Then, the average of those 10 points was taken as one result, and all the above-mentioned 10 ghost images were measured in the same manner. Their average value was determined. By this method, the other three colors were similarly processed, and evaluation was performed using an average value of these values. As the measurement result of each color, the result of each color of magenta, cyan, yellow, and black of the spectral densitometer X-Rite is displayed, and the value of the same color as the image color is used as the measurement value.

(Example 2)
An electrophotographic photosensitive member was prepared in the same manner as in Example 1 except that 2 parts of the exemplified compound E1-8 constituting the intermediate layer and 8 parts of poly (p-hydroxystyrene) were changed, and the same evaluation was performed. It was.

(Example 3)
An electrophotographic photoreceptor was prepared in the same manner as in Example 1 except that 3 parts of the exemplified compound E1-8 constituting the intermediate layer and 7 parts of poly (p-hydroxystyrene) were changed, and the same evaluation was performed. It was.

Example 4
An electrophotographic photosensitive member was prepared in the same manner as in Example 1 except that 3.5 parts of Exemplified Compound E1-8 constituting the intermediate layer and 6.5 parts of poly (p-hydroxystyrene) were changed. Was evaluated.

(Example 5)
An electrophotographic photosensitive member was produced in the same manner as in Example 1 except that 5 parts of the exemplified compound E1-8 constituting the intermediate layer and 5 parts of poly (p-hydroxystyrene) were changed, and the same evaluation was performed. It was.

(Example 6)
An electrophotographic photosensitive member was prepared in the same manner as in Example 1 except that 7 parts of Exemplified Compound E1-8 constituting the intermediate layer and 7 parts of poly (p-hydroxystyrene) were changed, and the same evaluation was performed. It was.

(Example 7)
An electrophotographic photosensitive member was prepared in the same manner as in Example 1 except that 8 parts of the exemplified compound E1-8 constituting the intermediate layer and 2 parts of poly (p-hydroxystyrene) were changed, and the same evaluation was performed. It was.

(Example 8)
Except for applying a solution prepared by dissolving 3 parts of Exemplified Compound E1-14 listed in Table 1, 7 parts of poly (p-hydroxystyrene) and 150 parts of DMF and 100 parts of methanol on a conductive support by a dip coating method. Produced an electrophotographic photosensitive member in the same manner as in Example 1, and performed the same evaluation.

Example 9
An electrophotographic photosensitive member was prepared in the same manner as in Example 8 except that 3.5 parts of Exemplified Compound E1-14 constituting the intermediate layer and 6.5 parts of poly (p-hydroxystyrene) were changed. Was evaluated.

(Example 10)
An electrophotographic photosensitive member was produced in the same manner as in Example 8 except that 5 parts of the exemplified compound E1-14 constituting the intermediate layer and 5 parts of poly (p-hydroxystyrene) were changed, and the same evaluation was performed. It was.

(Example 11)
An electrophotographic photosensitive member was prepared in the same manner as in Example 8 except that 7 parts of the exemplified compound E1-14 constituting the intermediate layer and 7 parts of poly (p-hydroxystyrene) were changed, and the same evaluation was performed. It was.

(Example 12)
On the conductive support, 3.5 parts of Exemplified Compound E1-14 listed in Table 1, 3.5 parts of poly (p-hydroxystyrene), 3.5 parts of 2,4-toluene diisocyanate, 150 parts of DMF, An electrophotographic photosensitive member was produced in the same manner as in Example 1 except that a solution dissolved in 100 parts of methanol was applied by a dip coating method, and the same evaluation was performed.

(Example 13)
Except for changing the exemplified compound E1-14 constituting the intermediate layer to 5 parts, poly (p-hydroxystyrene) to 2.5 parts, and 2,4-toluene diisocyanate to 2.5 parts, the same as in Example 1. An electrophotographic photosensitive member was prepared and evaluated in the same manner.

(Example 14)
The electrophotographic photosensitive member was the same as in Example 1 except that 7 parts of Exemplified Compound E1-14 constituting the intermediate layer, 1 part of poly (p-hydroxystyrene) and 2 parts of 2,4-toluene diisocyanate were changed. A body was prepared and evaluated in the same manner.

(Example 15)
A solution obtained by dissolving 3.5 parts of Exemplified Compound E2-8 listed in Table 2, 6.5 parts of poly (p-hydroxystyrene) in 150 parts of DMF and 100 parts of methanol on a conductive support is applied by dip coating. An electrophotographic photosensitive member was produced in the same manner as in Example 1 except that the coating was applied, and the same evaluation was performed.

(Example 16)
An electrophotographic photosensitive member was produced in the same manner as in Example 15 except that 5 parts of the exemplified compound E2-8 constituting the intermediate layer and 5 parts of poly (p-hydroxystyrene) were changed, and the same evaluation was performed. It was.

(Example 17)
An electrophotographic photosensitive member was produced in the same manner as in Example 15 except that Exemplified Compound E2-8 constituting the intermediate layer was changed to Exemplified Compound E2-18, and the same evaluation was performed.

(Example 18)
An electrophotographic photosensitive member was produced in the same manner as in Example 17 except that 5 parts of the exemplified compound E2-18 constituting the intermediate layer and 5 parts of poly (p-hydroxystyrene) were changed, and the same evaluation was performed. It was.

Example 19
An electrophotographic photosensitive member was prepared in the same manner as in Example 18 except that 2.5 parts of poly (p-hydroxystyrene) constituting the intermediate layer and 2.5 parts of 2,4-toluene diisocyanate were added. Was evaluated.

(Example 20)
An electrophotographic photosensitive member was prepared in the same manner as in Example 18 except that 1.5 parts of poly (p-hydroxystyrene) constituting the intermediate layer and 3.5 parts of 2,4-toluene diisocyanate were added. Was evaluated.

(Example 21)
An electrophotographic photosensitive member was produced in the same manner as in Example 18 except that poly (p-hydroxystyrene) constituting the intermediate layer was changed to polyvinyl naphthol, and the same evaluation was performed.

  Polyvinyl naphthol was synthesized as follows. 100 g of 1-vinyl-4-acetoxynaphthalene and azobisisobutyronitrile were dissolved in 500 ml of dehydrated tetrahydrofuran, and the reaction solution was sufficiently purged with nitrogen, and then reacted at 80 ° C. for 18 hours. Was cooled and poured into water. Polyvinyl naphthalene was obtained as a white precipitate.

  The obtained polyvinyl naphthalene was dispersed in 500 ml of methanol containing 20% dimethylaminopyridine and stirred at 50 ° C. to obtain a light yellow uniform solution. This solution was poured into water to obtain white polyvinyl naphthol. Reprecipitation was performed from tetrahydrofuran / water to obtain 42 g of purified polyvinyl naphthol.

(Example 22)
An electrophotographic photosensitive member was produced in the same manner as in Example 18 except that the poly (p-hydroxystyrene) constituting the intermediate layer was changed to polyvinyl hydroxyanthracene, and the same evaluation was performed.

  Polyvinylhydroxyanthracene was synthesized as follows. After 140 g of 9-vinyl-10-acetoxyanthracene and azobisisobutyronitrile were dissolved in 500 ml of dehydrated tetrahydrofuran and the reaction solution was sufficiently purged with nitrogen, the reaction was carried out at 85 ° C. for 20 hours. Was cooled and poured into water. Polyvinyl naphthalene was obtained as a white precipitate.

  The obtained polyvinyl naphthalene was dispersed in 500 ml of methanol containing 20% dimethylaminopyridine, and stirred at 50 ° C. to obtain a light yellow uniform solution. This solution was poured into water to obtain white polyvinyl naphthol. Reprecipitation was performed from tetrahydrofuran / water to obtain 50 g of purified polyvinyl naphthol.

(Example 23)
An electrophotographic photosensitive member was produced in the same manner as in Example 15 except that the exemplified compound E2-8 constituting the intermediate layer was changed to the exemplified compound E3-3, and the same evaluation was performed.

(Example 24)
An electrophotographic photosensitive member was produced in the same manner as in Example 23 except that 5 parts of the exemplified compound E3-3 constituting the intermediate layer and 5 parts of poly (p-hydroxystyrene) were changed, and the same evaluation was performed. It was.

(Example 25)
An electrophotographic photosensitive member was produced in the same manner as in Example 23 except that Exemplified Compound E3-3 constituting the intermediate layer was changed to Exemplified Compound E3-10, and the same evaluation was performed.

(Example 26)
An electrophotographic photosensitive member was produced in the same manner as in Example 23 except that 5 parts of the exemplified compound E3-10 constituting the intermediate layer and 5 parts of poly (p-hydroxystyrene) were changed, and the same evaluation was performed. It was.

(Example 27)
An electrophotographic photosensitive member was produced in the same manner as in Example 26 except that Exemplified Compound E3-10 constituting the intermediate layer was changed to Exemplified Compound E4-9, and the same evaluation was performed.

(Example 28)
Electrophotography in the same manner as in Example 27 except that the bisphenol C type polyarylate resin of the hole transport layer solution was changed to bisphenol Z type polycarbonate resin (trade name: Iupilon Z400, manufactured by Mitsubishi Engineering Plastics Co., Ltd.) A photoconductor was prepared and evaluated in the same manner.

(Example 29)
Crystalline oxytitanium having strong peaks at 9.0 °, 14.2 °, 23.9 ° and 27.1 ° of Bragg angles (2θ ± 0.2 °) in CuKα characteristic X-ray diffraction as a charge generation material An electrophotographic photosensitive member was produced in the same manner as in Example 27 except that phthalocyanine was used, and the same evaluation was performed.

(Example 30)
An electrophotographic photosensitive member was produced in the same manner as in Example 26 except that the exemplified compound E3-10 constituting the intermediate layer was changed to the exemplified compound E4-13, and the same evaluation was performed.

(Example 31)
An electrophotographic photosensitive member was prepared in the same manner as in Example 30 except that 2.5 parts of poly (p-hydroxystyrene) constituting the intermediate layer and 2.5 parts of 2,4-toluene diisocyanate were added. Was evaluated.

(Example 32)
An electrophotographic photosensitive member was prepared in the same manner as in Example 30 except that 1.5 parts of poly (p-hydroxystyrene) constituting the intermediate layer and 3.5 parts of 2,4-toluene diisocyanate were added. Was evaluated.

(Example 33)
An electrophotographic photosensitive member was produced in the same manner as in Example 24 except that the exemplified compound E3-3 constituting the intermediate layer was changed to the following structural formula (E5), and the same evaluation was performed.

(Example 34)
An electrophotographic photosensitive member was produced in the same manner as in Example 24 except that the exemplified compound E3-3 constituting the intermediate layer was changed to the following structural formula (E6), and the same evaluation was performed.

(Example 35)
An electrophotographic photosensitive member was produced in the same manner as in Example 34 except that 3 parts of the formula (E6) constituting the intermediate layer and 7 parts of poly (p-hydroxystyrene) were changed, and the same evaluation was performed. .

(Example 36)
Crystalline oxy having strong peaks at 9.0 °, 14.2 °, 23.9 ° and 27.1 ° of Bragg angles (2θ ± 0.2 °) in characteristic X-ray diffraction of CuKα as a charge generating material An electrophotographic photosensitive member was produced in the same manner as in Example 35 except that titanium phthalocyanine was used, and the same evaluation was performed.

(Comparative Example 1)
An electrophotographic photosensitive member was prepared and evaluated in the same manner as in Example 1 except that the exemplified compound E1-8 was not used as the intermediate layer coating solution, and poly (p-hydroxystyrene) was changed to 10 parts. It was.

(Comparative Example 2)
An electrophotographic photosensitive member was produced in the same manner as in Example 27 except that poly (p-hydroxystyrene) constituting the intermediate layer was changed to polystyrene, and the same evaluation was performed.

(Comparative Example 3)
Crystalline oxytitanium having strong peaks at 9.0 °, 14.2 °, 23.9 ° and 27.1 ° of Bragg angles (2θ ± 0.2 °) in CuKα characteristic X-ray diffraction as a charge generation material An electrophotographic photosensitive member was produced in the same manner as in Comparative Example 2 except that phthalocyanine was used, and the same evaluation was performed.

1 is a diagram illustrating an example of a schematic configuration of an electrophotographic apparatus including a process cartridge having the electrophotographic photosensitive member of the present invention. It is the 1 dot Keima pattern printed by the image evaluation of an Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Electrophotographic photoreceptor 2 Axis 3 Charging means 4 Exposure light 5 Developing means 6 Transfer means 7 Transfer material 8 Fixing means 9 Cleaning means 11 Process cartridge 12 Guide means

Claims (12)

  A laminated electrophotographic photosensitive member having, in this order, an intermediate layer containing an electron transport compound, a charge generation layer, and a hole transport layer containing a hole transport material on a conductive support, the intermediate layer comprising an alkylene main chain And an intermediate layer coating solution containing a thermoplastic resin containing a unit unit having a hydroxyaryl group in the side chain and an electron transport compound.   The electrophotographic photosensitive member according to claim 1, wherein the aryl group of the hydroxyaryl group is a phenyl group. The electrophotographic photosensitive member according to claim 1 or 2, wherein the electron transport compound is represented by any one of the following formulas (1) to (4):

(Wherein, X _{1 to} X ₄ each independently represent a hydrogen atom, a halogen group, a nitro group, an alkoxy group which may have a substituent or an alkyl group which may have a substituent. R ₁ and R 4 ₂ are each independently an alkyl group optionally interrupted by an ether group, an alkenyl group optionally interrupted by an ether group, a heterocyclic group; an alkyl group, an alkenyl group, a nitro group, a halogen group, a halogen-substituted alkyl group Aryl group or alkyl group which may have, alkenyl group, nitro group, halogen group, aralkyl group which may have halogen-substituted alkyl group, carbonyl group substituted with alkyl group, sulfonyl substituted with alkyl group Group.)

(Wherein, Z ₁ and Z ₂ each independently represent oxygen, C (CN) ₂ group or N—R (R represents an aryl group or alkyl group which may have a substituent), X _{11 to} X _18. Each independently represents a hydrogen atom, a hydroxyl group, a halogen atom, a nitro group, a trifluoroalkyl group, a carboxyl group, an amino group, an alkoxy group which may have a substituent, an alkyl group which may have a substituent, or a substituent. A carbonyl group optionally having a substituent, an ester group optionally having a substituent, or an aryl group optionally having a substituent.

(Wherein Z ₁₁ and Z ₁₂ each independently represent oxygen, C (CN) ₂ group or N—R (R represents an aryl group or alkyl group which may have a substituent), X _{21 to} X _26. Each independently represents a hydrogen atom, a hydroxyl group, a halogen atom, a nitro group, a trifluoroalkyl group, a carboxyl group, an amino group, an alkoxy group which may have a substituent, an alkyl group which may have a substituent, or a substituent. A carbonyl group optionally having a substituent, an ester group optionally having a substituent, or an aryl group optionally having a substituent.

(In the formula, Z ₂₁ and Z ₂₂ each independently represent oxygen, C (CN) ₂ group or N—R (R represents an aryl group or alkyl group which may have a substituent). X _{31 to} X _36. Each independently represents a hydrogen atom, a hydroxyl group, a halogen atom, a nitro group, a trifluoroalkyl group, a carboxyl group, an amino group, an alkoxy group which may have a substituent, an alkyl group which may have a substituent, or a substituent. A carbonyl group optionally having a substituent, an ester group optionally having a substituent, or an aryl group optionally having a substituent.   The electrophotographic photosensitive member according to claim 1, wherein the electron transport compound has a hydroxyl group.   The electrophotographic photosensitive member according to claim 1, wherein the intermediate coating solution further comprises a compound having an isocyanate group.   The electrophotographic photosensitive member according to claim 1, wherein the molar ratio of hydroxyl groups in the intermediate layer is larger than the ratio of the electron transport compound.   The electrophotographic photosensitive member according to claim 1, wherein the content of the electron transport compound in the intermediate layer is more than 30% by mass.   The electrophotographic photosensitive member according to claim 1, wherein the charge generation material in the charge generation layer is gallium phthalocyanine.   The electrophotographic photosensitive member according to claim 8, wherein the gallium phthalocyanine is hydroxygallium phthalocyanine.   The electrophotographic photosensitive member according to claim 1, wherein the hole transport layer contains polyarylate.   11. The electrophotographic photosensitive member according to claim 1, charging means for charging the electrophotographic photosensitive member, developing means for developing the electrophotographic photosensitive member on which an electrostatic latent image is formed with toner, and a transfer step A process cartridge characterized in that it integrally supports at least one means selected from the group consisting of cleaning means for collecting toner remaining on a later electrophotographic photosensitive member, and is detachable from the electrophotographic apparatus main body. .   An electrophotographic photosensitive member according to any one of claims 1 to 10, a charging means for charging the electrophotographic photosensitive member, an exposure means for exposing the charged electrophotographic photosensitive member to form an electrostatic latent image, An electrophotographic apparatus comprising: a developing unit that develops toner on an electrophotographic photosensitive member on which a latent image is formed; and a transfer unit that transfers a toner image on the electrophotographic photosensitive member onto a transfer material.