JP4483731B2 - Electrophotographic photosensitive member, electrophotographic cartridge, and electrophotographic apparatus - Google Patents

Description

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

  The electrophotographic system is used in electrophotographic apparatuses such as copying machines and laser beam printers because it can obtain high-quality printing at high speed. As the electrophotographic photosensitive member used in the electrophotographic apparatus, an organic electrophotographic photosensitive member using an organic photoconductive material has become the mainstream, and the configuration of the electrophotographic photosensitive member includes a charge transport material and a charge generating material. The performance has been improved by transitioning to a function-separated electrophotographic photosensitive member laminated as a separate layer.

  In the case of this function-separated electrophotographic photosensitive member, there is a case where an undercoat layer is first formed on an aluminum substrate (conductive substrate), and then a photosensitive layer comprising a charge generation layer and a charge transport layer is formed. Many.

In this case, there are many parts that depend on the charge generation layer and the charge transport layer as well as the undercoat layer for improving the stability and environmental stability of the electrophotographic photoreceptor when it is used repeatedly. There is a demand for a subbing layer with less.
In addition, the undercoat layer plays a major role in preventing image quality defects, and the undercoat layer is an important function for suppressing image quality defects caused by substrate defects or stains, or coating film defects or unevenness in the upper layer such as the charge generation layer. Is a layer.

In recent years, in particular, contact charging type charging devices that generate less ozone have been used instead of corotron in electrophotographic devices, and due to the local high electric field applied during contact charging to locally deteriorated parts of the electrophotographic photosensitive member, In some cases, a pinhole is generated, resulting in an image quality defect.
This pinhole leak may occur due to a coating film defect of the above-described electrophotographic photosensitive member itself, but in addition to this, conductive foreign matter generated from the inside of the electrophotographic apparatus is contacted or electrophotographic in the electrophotographic photosensitive member. This occurs because it penetrates into the photoconductor and easily forms a conductive path between the contact charging device and the conductive substrate. In a noticeable case, foreign matter mixed from other members in the electrophotographic apparatus or dust mixed in the electrophotographic apparatus may pierce the electrophotographic photosensitive member to form a leak point from the contact charging device.

In order to solve such a problem, there is a method in which a layer containing a conductive fine powder is formed on a substrate in order to conceal defects in the substrate by thickening the undercoat layer and to obtain stability in electrical characteristics. It has been taken so far.
One of them is a method in which a conductive powder-dispersed conductive layer is formed on an aluminum substrate and an undercoat layer is formed thereon. In this case, the base material is concealed by the conductive layer and the resistance is adjusted, and the blocking (charge injection control) function is provided by the undercoat layer.

As another method, a conductive powder dispersion layer having both functions of blocking (charge injection control) and resistance adjustment is applied on the substrate, and the functions of the blocking (charge injection control) layer and resistance adjustment layer are both applied. It is a method used as an undercoat layer.
Since the number of stacked layers in the latter undercoating layer is one less than that in the former undercoating layer method, the manufacturing process of the electrophotographic photosensitive member can be simplified and the cost can be reduced.

From the viewpoint of preventing leakage, the thicker the undercoat layer, the greater the effect. A thick film thickness of 10 μm or more is required. However, in order to obtain good electrical characteristics and ghost when the film thickness is increased, Consideration has been made.
In particular, in recent years, expectations for development of a long-life electrophotographic photosensitive member have increased due to increasing awareness of environmental problems, and it has become essential to improve the stability of electrical characteristics and image quality during repeated use over a long period of time. Furthermore, there is a great demand for electrophotographic photosensitive members from the viewpoint of high image quality such as ghost stress.

  In order for such an undercoat layer of a thick film to stabilize electrical characteristics and ghosts, it is necessary to satisfy the conditions necessary for carriers to flow smoothly at the interface between the undercoat layer and the photosensitive layer and the undercoat layer bulk. There is. Specifically, in the case of a negatively charged system, it is desired that the hole injection property from the undercoat layer to the photosensitive layer is low, and conversely, the electron injection property from the photosensitive layer to the undercoat layer is high.

  When the hole injection property from the undercoat layer to the photosensitive layer is high in response to the above requirement, it causes fogging and black spots, resulting in image quality defects. In addition, when the electron injection property from the photosensitive layer to the undercoat layer is low, the image quality may be deteriorated due to ghosting or cycle-up of electrical characteristics over a long period of time. Regarding the undercoat layer bulk, an undercoat layer having a high conductivity without deep trap sites is desired regardless of electrons and holes. If these conditions are not satisfied, cycle stability is deteriorated and ghosts are caused.

  Many studies have been conducted recently to meet these requirements. For example, as a means for improving the hole injection preventing property from the undercoat layer to the photosensitive layer, a means for improving the hole blocking property using a silane coupling agent containing an amino group has been proposed (for example, (See Patent Documents 1 and 2).

Further, as a means for improving the electron injection property from the photosensitive layer to the undercoat layer, a technique for adding an additive such as an electron accepting substance or an electron transporting substance to the undercoat layer has been proposed (for example, a patent Reference 3-5).
Japanese Patent Application Laid-Open No. 08-166679 JP 11-133649 A JP 07-175249 A JP 08-44097 A JP 09-197701 A

  However, even when these methods are used, it is not possible to obtain an undercoat layer that can satisfy the characteristic values required for the electrophotographic photosensitive member under actual use conditions, particularly for ghost and long-term cycle stability. It was. That is, there are various problems with respect to means for stably improving the electron injection property from the photosensitive layer to the undercoat layer without being affected by the environment and the print history.

  The present invention has been made in view of such problems, and can suppress the occurrence of ghosts, and even when used repeatedly, there are few fluctuations in electrical characteristics, the occurrence of image quality defects, and image quality such as pinhole leaks. An object of the present invention is to provide an electrophotographic photosensitive member, an electrophotographic cartridge, and an electrophotographic apparatus that do not cause defects.

  As a result of intensive studies, the present inventors are an electrophotographic photoreceptor having at least an undercoat layer and a photosensitive layer on a conductive substrate, and the undercoat layer contains an acceptor compound in a solid state in the layer. By doing so, it was found that the above-mentioned problems, in particular, ghosting and stabilization of electrical characteristics in the long term can be solved. The reason for this is that the acceptor compound that exists in the form of particles as a solid substance at the interface between the undercoat layer and the photosensitive layer and the bulk of the undercoat layer is more effective for electron injectability and electron mobility. It seems to function.

That is, it seems to suggest that the contact between the acceptor compound and the photosensitive layer can be further ensured by allowing the acceptor compound to exist in the form of particles, for example. The maximum length of the solid acceptor compound is preferably 10 μm or less because it causes fogging and black spots when it exceeds 10 μm.
When the solid acceptor compound has a maximum length of 10 μm or less and a state where it is uniformly contained in the layer can be observed, problems such as black spots hardly occur.

  Furthermore, since the undercoat layer contains metal oxide fine particles surface-treated with a silane coupling agent, it is possible to obtain good image quality with few image quality defects such as fog and black spots. Further, by increasing the thickness of the undercoat layer, the occurrence of leakage can be sufficiently prevented even if foreign matter generated from members around the electrophotographic photosensitive member or dust entering from the outside of the electrophotographic apparatus is pierced. Accordingly, it is possible to obtain sufficiently good image quality over a long period of time.

That is, the present invention
<1> In an electrophotographic photosensitive member having at least an undercoat layer and a photosensitive layer on a conductive substrate, the undercoat layer includes an acceptor compound containing an anthraquinone structure having a hydroxyl group in a dispersed state as a solid substance. An electrophotographic photoreceptor.

<2> The electrophotographic photosensitive member according to <1>, wherein the maximum length of the solid matter is 10 μm or less.

< 3 > The electrophotographic photosensitive member according to <1> or <2> , wherein the acceptor compound including an anthraquinone structure having a hydroxyl group is a hydroxyanthraquinone compound or an aminohydroxyanthraquinone compound.

< 4 > The electrophotographic photosensitive member according to any one of <1> to < 3 >, wherein the undercoat layer includes metal oxide fine particles in addition to the acceptor compound.

< 5 > The electrophotographic photosensitive member according to < 4 >, wherein the metal oxide fine particles are surface-treated.

< 6 > The electrophotographic photosensitive member according to < 5 >, wherein the surface treatment is a surface treatment using a silane coupling agent.

< 7 > The electrophotographic photosensitive member according to < 6 >, wherein the silane coupling agent is a silane coupling agent having an amino group.

< 8 > The electron according to any one of < 4 > to < 7 >, wherein the metal oxide fine particles are at least one selected from titanium oxide, zinc oxide, tin oxide, and acid value zirconium. It is a photographic photoreceptor.

< 9 > The electrophotographic photosensitive member according to any one of <1> to < 8 >, wherein the photosensitive layer has a charge generation layer, and the charge generation layer contains at least either a phthalocyanine pigment or an azo pigment. It is.

< 10 > The electrophotographic photosensitive member according to < 9 >, wherein the phthalocyanine pigment is at least one selected from a hydroxygallium phthalocyanine pigment, a chlorogallium phthalocyanine pigment, an oxotitanyl phthalocyanine pigment, and a metal-free phthalocyanine pigment. .

< 11 > The electrophotographic photosensitive member according to any one of <1> to < 10 >, which contains fluorine-based resin particles on the outermost surface.
<12> The undercoat layer is obtained by applying a coating solution in which the acceptor compound is dispersed in a solvent containing a nonpolar solvent to the conductive substrate and drying the coating solution. <1> to the electrophotographic photoreceptor according to any one of <11>.

<13> An electrophotographic cartridge comprising at least the electrophotographic photosensitive member according to any one of <1> to <12> and a charging unit that charges the electrophotographic photosensitive member.

<14> An electrophotographic apparatus comprising at least the electrophotographic photosensitive member according to any one of <1> to <12> and a charging unit that charges the electrophotographic photosensitive member.

<15> The electrophotographic apparatus according to <14>, wherein the charging unit is a charging unit that contacts the electrophotographic photosensitive member to charge the electrophotographic photosensitive member.

<16> The electrophotographic apparatus according to <14> or <15>, further including an intermediate transfer unit that transfers an image formed on the electrophotographic photosensitive member.

  According to the configuration of the present invention, it is possible to suppress the occurrence of ghosts, and even when used repeatedly, the electrophotographic photosensitive member is less likely to cause fluctuations in electrical characteristics and image quality defects, and does not cause image quality defects such as pinhole leaks. An electrophotographic cartridge and an electrophotographic apparatus can be provided.

Hereinafter, the present invention will be described in detail.
<Electrophotographic photoreceptor>
The electrophotographic photoreceptor of the present invention is an electrophotographic photoreceptor having at least an undercoat layer and a photosensitive layer on a conductive substrate, wherein the undercoat layer includes an acceptor compound dispersed in a solid state. It is characterized by.

Hereinafter, preferred embodiments of the electrophotographic photosensitive member of the present invention will be described in detail. In addition, the same code | symbol shall be attached | subjected to the same or an equivalent part in the following drawings, and the overlapping description is abbreviate | omitted.
FIG. 1 is a schematic cross-sectional view showing an example of an electrophotographic photoreceptor according to the present invention. The electrophotographic photosensitive member 7 has a structure in which an undercoat layer 2, an intermediate layer 4, a photosensitive layer 3, and a protective layer 5 are sequentially laminated on a conductive substrate 1. The electrophotographic photoreceptor 7 shown in FIG. 1 is a function-separated photoreceptor, and the photosensitive layer 3 includes a charge generation layer 31 and a charge transport layer 32.

  As the conductive substrate 1, a metal drum such as aluminum, copper, iron, stainless steel, zinc, nickel, etc .; on a base material such as sheet, paper, plastic, glass, aluminum, copper, gold, silver, platinum, palladium, titanium, Deposited metal such as nickel-chromium, stainless steel, copper, indium, etc., or deposited conductive metal compound such as indium oxide, tin oxide; laminated metal foil on the substrate or carbon black, Indium oxide, tin oxide, antimony oxide powder, metal powder, copper iodide and the like are dispersed in a binder resin and subjected to a conductive treatment by coating it;

  The shape of the conductive substrate 1 is not limited to a drum shape, and may be a sheet shape or a plate shape. In addition, when the conductive substrate 1 is a metal pipe, the surface may be left as it is, or a process such as mirror cutting, etching, anodizing, rough cutting, centerless grinding, sand blasting, wet honing, etc. may be performed in advance. It may be done.

An undercoat layer 2 is formed on the conductive substrate. In the present invention, the undercoat layer 2 contains the acceptor compound in a dispersed state as a solid.
Here, the above-mentioned “solid matter” is not dissolved in the binder resin constituting the undercoat layer 2 as a molecular state but is dispersed in a state incompatible (separated) with the binder resin. .

  Thus, by dispersing the acceptor compound as a solid in the undercoat layer 2 in a relatively large size, the solid is exposed from the surface of the undercoat layer, and in the photosensitive layer 3 provided on the undercoat layer 2. In addition, since the acceptor compound can directly hit the head, the charge transfer from the photosensitive layer 3 to the undercoat layer 2 is smooth, and the cycle of electrical characteristics can be more efficiently prevented from being repeatedly used.

  The shape of the solid matter includes not only particles but also various indefinite shapes such as a line and a rod. Furthermore, shapes such as aggregates of fine particles are also included. The undercoat layer 2 of the present invention contains metal oxide fine particles as will be described later. In this case, one or more of the particulate acceptor compounds are firmly attached to the surface of the metal compound fine particles ( It is more preferable to take a form that includes chemical bonding at the interface.

Furthermore, the solid material in the present invention includes particles formed by coating the acceptor compound in a solid state on the surface of the metal compound fine particles, in addition to those formed by the acceptor compound alone.
In addition, in the undercoat layer 2 in this invention, the acceptor compound melt | dissolved in the molecular form may be contained besides the acceptor compound being contained as said solid substance.

  As the acceptor compound, any compound can be used as long as the desired properties can be obtained, but a compound having a quinone group is particularly preferably used. Furthermore, an acceptor compound having an anthraquinone structure is preferably used.

As an acceptor compound in this invention, it is preferable to have a group which can react with the metal oxide fine particle mentioned later, and especially the compound containing the anthraquinone structure which has a hydroxyl group is used. Examples of the compound containing an anthraquinone structure having a hydroxyl group include a hydroxyanthraquinone compound and an aminohydroxyanthraquinone compound, and any of them can be preferably used. More specifically, alizarin, quinizarin, anthralfin, purpurin, 1-hydroxyanthraquinone, 2-amino-3-hydroxyanthraquinone, 1-amino-4-hydroxyanthraquinone and the like are particularly preferably used.

In the present invention, the content of the acceptor compound in the undercoat layer (including those that are partly present in molecular form) is preferably in the range of 0.004 to 16% by mass, and in the range of 0.02 to 8% by mass. It is more preferable that
When the content is less than 0.004% by mass, even if the acceptor compound is dispersed in the undercoat layer as a solid content, the exposed amount of the surface of the undercoat layer is not sufficient, and the charge transfer from the photosensitive layer is smooth. May not be done. If it exceeds 16% by mass, the dispersion state of the solid content may become non-uniform, which may cause black spots.

  Further, when the metal oxide fine particles described later are contained in the undercoat layer, the acceptor compound is preferably used in the range of 0.01 to 20 parts by mass with respect to 100 parts by mass of the metal oxide fine particles. More preferably, it is used in the range of 0.05 to 10 parts by mass with respect to 100 parts by mass of the metal oxide fine particles. If the amount is less than 0.01 parts by mass, sufficient acceptor properties that contribute to the improvement of charge accumulation in the undercoat layer cannot be imparted, and thus the sustainability such as an increase in residual potential is likely to occur during repeated use. Further, if the amount exceeds 20 parts by mass, the metal oxide fine particles are likely to aggregate, and the metal oxide cannot form a good conductive path in the undercoat layer when the undercoat layer is formed. This not only tends to cause deterioration in maintainability such as an increase in image quality, but also tends to cause image quality defects such as black spots.

  The undercoat layer 2 in the present invention preferably contains metal oxide fine particles in addition to the acceptor compound. By containing the metal compound fine particles, the increase in resistance of the undercoat layer can be controlled even if the thickness of the undercoat layer 2 is increased.

As the metal oxide fine particles used in the present invention, a powder having a volume resistivity in the range of 10 ² to 10 ¹¹ Ω · cm is preferably used. The reason is that it is necessary for the undercoat layer 2 to obtain an appropriate resistance for obtaining leak resistance. If the volume resistivity of the metal oxide fine particles is lower than 10 ² Ωcm, sufficient leakage resistance cannot be obtained, and if it is higher than 10 ¹¹ Ωcm, there is a concern that the residual potential is increased.

Among them, it is preferable to use fine metal oxide particles such as tin oxide, titanium oxide, zinc oxide and zirconium oxide having the volume resistivity. In particular, zinc oxide is preferably used.
As the metal oxide fine particles, a mixture of two or more types having different surface treatments or different particle diameters can be used. As the metal oxide fine particles, those having a specific surface area of 10 m ² / g or more are preferably used. Those having a specific surface area value of 10 m ² / g or less are liable to cause a decrease in chargeability and have a drawback that it is difficult to obtain good electrophotographic characteristics. In addition, it is preferable that the volume average particle diameter of a metal oxide particle is the range of 50-200 nm.

  The metal oxide fine particles in the present invention can be subjected to a surface treatment. The surface treatment agent can be selected from known materials as long as desired characteristics can be obtained, such as a silane coupling agent, a titanate coupling agent, an aluminum coupling agent, and a surfactant. In particular, silane coupling agents are preferably used because they give good electrophotographic characteristics. Furthermore, a silane coupling agent having an amino group is preferably used because it gives a good blocking property to the undercoat layer.

  As the silane coupling agent having an amino group, any one can be used as long as the desired photoreceptor characteristics can be obtained. Specific examples include γ-aminopropyltriethoxysilane, N-β-. (Aminoethyl) -γ-aminopropyltrimethoxysilane, N-β- (aminoethyl) -γ-aminopropylmethylmethoxysilane, N, N-bis (β-hydroxyethyl) -γ-aminopropyltriethoxysilane, etc. However, it is not limited to these.

  Moreover, 2 or more types of silane coupling agents can also be mixed and used. Examples of the silane coupling agent that can be used in combination with the silane coupling agent having an amino group include vinyltrimethoxysilane, γ-methacryloxypropyl-tris (β-methoxyethoxy) silane, β- (3 , 4-epoxycyclohexyl) ethyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, vinyltriacetoxysilane, γ-mercaptopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N-β- (aminoethyl) -Γ-aminopropyltrimethoxysilane, N-β- (aminoethyl) -γ-aminopropylmethylmethoxysilane, N, N-bis (β-hydroxyethyl) -γ-aminopropyltriethoxysilane, γ-chloropropyl Examples include trimethoxysilane, The present invention is not limited to these.

As the surface treatment method, any known method can be used, but a dry method or a wet method can be used.
When surface treatment is performed by a dry method, a silane coupling agent dissolved directly or in an organic solvent is added dropwise with dry air or nitrogen gas while stirring the metal oxide fine particles with a mixer having a large shearing force. It is uniformly processed by spraying. The addition or spraying is preferably performed at a temperature below the boiling point of the solvent. Spraying at a temperature equal to or higher than the boiling point of the solvent is not preferred because it causes the solvent to evaporate before being stirred uniformly, causing the silane coupling agent to locally accumulate and making uniform processing difficult. After addition or spraying, baking can be performed at 100 ° C. or higher. Baking can be carried out in an arbitrary range as long as the temperature and time allow the desired electrophotographic characteristics to be obtained.

  As a wet method, the metal oxide fine particles are stirred in a solvent, dispersed using ultrasonic waves, a sand mill, an attritor, a ball mill, etc., added with a silane coupling agent solution and stirred or dispersed, and then the solvent is removed. Uniformly processed. The solvent removal method is distilled off by filtration or distillation. After removing the solvent, baking can be performed at 100 ° C. or higher. Baking can be carried out in an arbitrary range as long as the temperature and time allow the desired electrophotographic characteristics to be obtained. In the wet method, the water containing metal oxide fine particles can be removed before adding the surface treatment agent. For example, a method of removing with stirring and heating in the solvent used for the surface treatment, removing by azeotroping with the solvent. It is also possible to use a method of

  The amount of the silane coupling agent relative to the metal oxide fine particles in the undercoat layer 2 can be arbitrarily set as long as desired electrophotographic characteristics can be obtained.

  As the binder resin contained in the undercoat layer 2, any known resin can be used as long as it can form a good film and can obtain desired characteristics. For example, acetal such as polyvinyl butyral can be used. Resin, polyvinyl alcohol resin, casein, polyamide resin, cellulose resin, gelatin, polyurethane resin, polyester resin, methacrylic resin, acrylic resin, polyvinyl chloride resin, polyvinyl acetate resin, vinyl chloride-vinyl acetate-maleic anhydride resin, silicone resin , Using known polymer resin compounds such as silicone-alkyd resin, phenol resin, phenol-formaldehyde resin, melamine resin, urethane resin, charge transport resin having a charge transport group, or conductive resin such as polyaniline, etc. Can do. Of these, resins insoluble in the upper coating solvent are preferably used, and phenol resins, phenol-formaldehyde resins, melamine resins, urethane resins, epoxy resins, and the like are particularly preferably used.

  The ratio between the metal oxide fine particles and the binder resin in the coating solution for forming the undercoat layer can be arbitrarily set within a range in which desired electrophotographic photoreceptor characteristics can be obtained.

Various additives can be used in the coating liquid for forming the undercoat layer in order to improve electrical characteristics, environmental stability, and image quality.
Examples of the additive include quinone compounds such as chloranil and bromoanil, tetracyanoquinodimethane compounds, fluorenone compounds such as 2,4,7-trinitrofluorenone and 2,4,5,7-tetranitro-9-fluorenone. 2- (4-biphenyl) -5- (4-t-butylphenyl) -1,3,4-oxadiazole and 2,5-bis (4-naphthyl) -1,3,4-oxadiazole Oxadiazole compounds such as 2,5-bis (4-diethylaminophenyl) -1,3,4-oxadiazole, xanthone compounds, thiophene compounds, 3,3 ′, 5,5′-tetra-t -Electron transporting substances such as diphenoquinone compounds such as butyldiphenoquinone, electron transporting pigments such as polycyclic condensation systems and azo systems, zirconium chelate compounds, titanium chelate compounds, aluminum compounds Over preparative compounds, titanium alkoxide compounds, organic titanium compounds, there can be used a known material such as a silane coupling agent.

  The silane coupling agent is used for the surface treatment of the metal oxide particles, but it can also be used as an additive added to the coating solution. Specific examples of the silane coupling agent used here include vinyltrimethoxysilane, γ-methacryloxypropyl-tris (β-methoxyethoxy) silane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, γ -Glycidoxypropyltrimethoxysilane, vinyltriacetoxysilane, γ-mercaptopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N-β- (aminoethyl) -γ-aminopropyltrimethoxysilane, N-β -(Aminoethyl) -γ-aminopropylmethylmethoxysilane, N, N-bis (β-hydroxyethyl) -γ-aminopropyltriethoxysilane, γ-chloropropyltrimethoxysilane, and the like.

  Examples of the zirconium chelate compound include zirconium butoxide, zirconium zirconium acetoacetate, zirconium triethanolamine, acetylacetonate zirconium butoxide, ethyl acetoacetate butoxide, zirconium acetate, zirconium oxalate, zirconium lactate, zirconium phosphonate, octane. Zirconate, zirconium naphthenate, zirconium laurate, zirconium stearate, zirconium isostearate, methacrylate zirconium butoxide, stearate zirconium butoxide, isostearate zirconium butoxide and the like.

  Examples of the titanium chelate compounds include tetraisopropyl titanate, tetranormal butyl titanate, butyl titanate dimer, tetra (2-ethylhexyl) titanate, titanium acetylacetonate, polytitanium acetylacetonate, titanium octylene glycolate, and titanium lactate ammonium. Examples thereof include salts, titanium lactate, titanium lactate ethyl ester, titanium triethanolamate, and polyhydroxytitanium stearate.

Examples of the aluminum chelate compound include aluminum isopropylate, monobutoxy aluminum diisopropylate, aluminum butyrate, diethyl acetoacetate aluminum diisopropylate, aluminum tris (ethyl acetoacetate) and the like.
These compounds can be used alone or as a mixture or polycondensate of a plurality of compounds.

  The solvent for preparing the coating solution for forming the undercoat layer is arbitrarily selected from known organic solvents such as alcohols, aromatics, halogenated hydrocarbons, ketones, ketone alcohols, ethers, esters, etc. You can choose. For example, methanol, ethanol, n-propanol, iso-propanol, n-butanol, benzyl alcohol, methyl cellosolve, ethyl cellosolve, acetone, methyl ethyl ketone, cyclohexanone, methyl acetate, ethyl acetate, n-butyl acetate, dioxane, tetrahydrofuran, Usual organic solvents such as methylene chloride, chloroform, chlorobenzene, and toluene can be used.

  Moreover, the solvent used for these dispersion | distribution can be used individually or in mixture of 2 or more types. When mixing, any solvent can be used as long as it can dissolve the binder resin as the mixed solvent.

  In selecting the solvent, it is important to use a solvent (poor solvent) having poor solubility of the acceptor compound in order to leave the acceptor compound in a state of being dispersed as a solid in the undercoat layer. Since acceptor compounds are generally highly polar, they are often poorly soluble in nonpolar solvents. As the nonpolar solvent, hydrocarbon solvents such as hexane, octane and cyclohexane are preferably used. Moreover, when mixing and using the said 2 or more types of solvent, it is preferable to mix | blend so that the said nonpolar solvent may become main.

  In the present invention, the coating solution for forming the undercoat layer is prepared by selecting an optimum solvent for solidifying the acceptor compound, and mixing the optimum amount of the acceptor compound, the binder resin, and further, metal oxide fine particles as a preferred embodiment. To do. In this case, the acceptor compound and metal oxide fine particles may be added after the binder resin is first dissolved in the solvent.

As a method for dispersing the acceptor compound after mixing these, known methods such as a roll mill, a ball mill, a vibrating ball mill, an attritor, a sand mill, a colloid mill, and a paint shaker can be used.
In the present invention, it is preferable to disperse the acceptor compound solid as uniformly as possible in the undercoat layer, and from this point of view, it is desirable to disperse the acceptor compound for a certain period of time with a certain shearing force.

  As the dispersion condition, for example, dispersion by a sand mill using glass beads having a diameter of 1 mm (filling ratio: about 70 to 95%) is preferably dispersed for 0.1 to 100 hours.

  Further, as the coating method used when the undercoat layer 2 is provided, conventional methods such as blade coating method, wire bar coating method, spray coating method, dip coating method, bead coating method, air knife coating method, curtain coating method and the like are used. Can be used.

In addition, when the metal oxide fine particles and the acceptor compound are reacted, the coating is performed even if the metal oxide fine particles and the acceptor compound having a group capable of reacting with the metal oxide fine particles react in the dispersion step. The reaction may be performed during the drying and curing of the film, but it is preferable to react in the dispersion because it reacts uniformly.
The undercoat layer 2 is formed on the conductive substrate using the undercoat layer forming coating solution thus obtained.

The formed undercoat layer 2 preferably has a Vickers strength of 35 or more. The volume resistivity of the undercoat layer 2 is preferably in the range of 10 ⁶ to 10 ¹³ Ωcm, and more preferably in the range of 10 ⁸ to 10 ¹² Ωcm.
If the volume resistivity is less than 10 ⁶ Ωcm, the charging potential may not be sufficient or leakage may occur. On the other hand, if it exceeds 10 ¹³ Ωcm, stable potential characteristics may not be obtained by repeated use.

Further, the undercoat layer 2 can be set to any thickness as long as desired characteristics can be obtained, but the thickness is preferably 15 μm or more, and more preferably 15 μm or more and 50 μm or less. .
When the thickness of the undercoat layer 2 is less than 15 μm, sufficient leakage resistance cannot be obtained, and when it exceeds 50 μm, a residual potential tends to remain during long-term use, and thus there is a drawback that an image density abnormality is likely to occur. .

Further, the surface roughness of the undercoat layer 2 is adjusted to ¼n (n is the refractive index of the upper layer) to ½λ of the exposure laser wavelength λ used in order to prevent moire images. In order to adjust the surface roughness, particles such as a resin can be added to the undercoat layer. As the resin particles, silicone resin particles, cross-linked PMMA resin particles, and the like can be used.
In addition, the undercoat layer can be polished to adjust the surface roughness. As a polishing method, buffing, sand blasting, wet honing, grinding, or the like can be used.

  In the undercoat layer 2 as described above, the maximum length of the solid acceptor compound (formed by the acceptor compound alone) in the present invention is preferably 10 μm or less, and is in the range of 0.01 to 2 μm. It is more preferable. Here, the maximum length is the length of the longest part in various forms of solids. In the present invention, the “maximum length is a to b μm” is within a certain range when the undercoat layer is observed with a microscope. When the maximum length is measured for 100 solids existing in the above, it means the maximum length of 50 or more of them.

  If the maximum length is less than 0.01 μm, even if the acceptor compound is dispersed in the undercoat layer as a solid content of a certain amount or more, the surface of the undercoat layer is not sufficiently exposed and the charge transfer from the photosensitive layer is smooth. May not be done. If it exceeds 10 μm, the uniformity as the undercoat layer is also lowered, which may cause image defects.

In the electrophotographic photosensitive member of the present invention, an intermediate layer 4 is further provided between the undercoat layer 2 and the photosensitive layer 3 in order to improve electrical characteristics, improve image quality, improve image quality maintenance, improve photosensitive layer adhesion, and the like. May be.
The intermediate layer 4 includes an acetal resin such as polyvinyl butyral, polyvinyl alcohol resin, casein, polyamide resin, cellulose resin, gelatin, polyurethane resin, polyester resin, methacrylic resin, acrylic resin, polyvinyl chloride resin, polyvinyl acetate resin, vinyl chloride. -Organic metals containing zirconium, titanium, aluminum, manganese, silicon atoms, etc. in addition to polymer resin compounds such as vinyl acetate-maleic anhydride resin, silicone resin, silicone-alkyd resin, phenol-formaldehyde resin, melamine resin A compound or the like can be used. These compounds can be used alone or as a mixture or polycondensate of a plurality of compounds. Among them, an organometallic compound containing zirconium or silicon is excellent in performance such as a low residual potential, a small potential change due to the environment, and a small potential change due to repeated use.

  Examples of silicon compounds include vinyltrimethoxysilane, γ-methacryloxypropyl-tris (β-methoxyethoxy)) silane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, γ-glycidoxypropyltri Methoxysilane, vinyltriacetoxysilane, γ-mercaptopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N-β- (aminoethyl) -γ-aminopropyltrimethoxysilane, N-β- (aminoethyl)- γ-aminopropylmethylmethoxysilane, N, N-bis (β-hydroxyethyl) -γ-aminopropyltriethoxysilane, γ-chloropropyltrimethoxysilane, and the like.

  Among these, particularly preferably used silicon compounds are vinyltriethoxysilane, vinyltris (2-methoxyethoxysilane), 3-methacryloxypropyltrimethoxysilane, 3-licidoxypropyltrimethoxysilane, 2- (3,4- Epoxycyclohexyl) ethyltrimethoxysilane, N-2- (aminoethyl) -3-aminopropyltrimethoxysilane, N-2- (aminoethyl) -3-aminopropylmethyldimethoxysilane, 3-aminopropyltriethoxysilane, Examples include silane coupling agents such as N-phenyl-3-aminopropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, and 3-chloropropyltrimethoxysilane.

  Examples of organic zirconium compounds include zirconium butoxide, zirconium zirconium acetoacetate, zirconium triethanolamine, acetylacetonate zirconium butoxide, ethyl acetoacetate butoxide, zirconium acetate, zirconium oxalate, zirconium lactate, zirconium phosphonate, zirconium octoate, Zirconium naphthenate, zirconium laurate, zirconium stearate, zirconium isostearate, methacrylate zirconium butoxide, stearate zirconium butoxide, isostearate zirconium butoxide and the like.

  Examples of organic titanium compounds include tetraisopropyl titanate, tetranormal butyl titanate, butyl titanate dimer, tetra (2-ethylhexyl) titanate, titanium acetylacetonate, polytitanium acetylacetonate, titanium octylene glycolate, titanium lactate ammonium salt , Titanium lactate, titanium lactate ethyl ester, titanium triethanolamate, polyhydroxy titanium stearate and the like.

  Examples of organoaluminum compounds include aluminum isopropylate, monobutoxy aluminum diisopropylate, aluminum butyrate, diethyl acetoacetate aluminum diisopropylate, aluminum tris (ethyl acetoacetate) and the like.

  The intermediate layer 4 plays the role of an electrical blocking layer in addition to improving the coatability of the upper layer. However, when the film thickness is too large, the electrical barrier becomes too strong and the potential increases due to desensitization or repetition. cause. Therefore, when the intermediate layer 4 is formed, the film thickness range is set to 0.1 to 5 μm.

Next, the photosensitive layer 3 formed on the undercoat layer will be described.
The charge generation layer 31 constituting the photosensitive layer 3 is formed by forming a charge generation material by vacuum vapor deposition or by applying a dispersion containing the charge generation material. When the charge generation layer 31 is formed by applying a dispersion, the charge generation layer 31 is formed by dispersing the charge generation material together with an organic solvent, a binder resin, an additive, and the like, and applying the obtained dispersion.

In the present invention, any known charge generating material can be used as the charge generating material.
For infrared light, phthalocyanine pigments, azo pigments such as squarylium, bisazo, trisazo, perylene, dithioketopyrrolopyrrole, for visible light, condensed polycyclic pigments, bisazo pigments, perylene, trigonal selenium, dye-sensitized zinc oxide fine particles Etc. are used. Among these, phthalocyanine pigments and azo pigments are used as charge generating materials that are particularly excellent and that are preferably used. By using this, it is possible to obtain the electrophotographic photosensitive member 7 with particularly high sensitivity and excellent repetitive stability.

  Further, phthalocyanine pigments and azo pigments generally have several crystal types, and any of these crystal types can be used as long as it is a crystal type capable of obtaining electrophotographic characteristics suitable for the purpose. Particularly preferably used charge generating substances include chlorogallium phthalocyanine, dichlorosus phthalocyanine, hydroxygallium phthalocyanine, metal-free phthalocyanine, oxytitanyl phthalocyanine, chloroindium phthalocyanine and the like.

  The phthalocyanine pigment crystal is obtained by mechanically dry-pulverizing a phthalocyanine pigment produced by a known method with an automatic mortar, planetary mill, vibration mill, CF mill, roller mill, sand mill, kneader, etc. It can manufacture by performing a wet grinding process using a ball mill, a mortar, a sand mill, a kneader, etc.

  Solvents used in the above treatment are aromatics (toluene, chlorobenzene, etc.), amides (dimethylformamide, N-methylpyrrolidone, etc.), aliphatic alcohols (methanol, ethanol, butanol, etc.), aliphatic polyvalents. Alcohols (ethylene glycol, glycerin, polyethylene glycol, etc.), aromatic alcohols (benzyl alcohol, phenethyl alcohol, etc.), esters (acetic ester, butyl acetate, etc.), ketones (acetone, methyl ethyl ketone, etc.), dimethyl sulfoxide, ether (Diethyl ether, tetrahydrofuran, etc.), several mixed systems, and mixed systems of water and these organic solvents.

  The solvent to be used is used in the range of 1 to 200 parts by mass, preferably 10 to 100 parts by mass with respect to 1 part by mass of the pigment crystal. The treatment temperature is preferably −20 ° C. to the boiling point of the solvent, preferably −10 to 60 ° C. In addition, grinding aids such as sodium chloride and sodium nitrate can be used during grinding. The grinding aid may be used 0.5 to 20 times, preferably 1 to 10 times the pigment.

  In addition, phthalocyanine pigment crystals produced by a known method can be controlled by combining acid pasting or acid pasting with dry pulverization or wet pulverization as described above. As an acid used for acid pasting, sulfuric acid is preferable, and one having a concentration of 70 to 100%, preferably 95 to 100% is used, and a dissolution temperature is in a range of -20 to 100 ° C, preferably -10 to 60 ° C. Is set. The amount of sulfuric acid is set in the range of 1 to 100 times, preferably 3 to 50 times the weight of the phthalocyanine pigment crystals. As a solvent to be precipitated, water or a mixed solvent of water and an organic solvent is used in an arbitrary amount. The temperature for precipitation is not particularly limited, but it is preferably cooled with ice or the like in order to prevent heat generation.

  The binder resin used for the charge generation layer 31 can be selected from a wide range of insulating resins, and is selected from organic photoconductive polymers such as poly-N-vinylcarbazole, polyvinylanthracene, polyvinylpyrene, and polysilane. You can also. Preferred binder resins include polyvinyl acetal resin, polyarylate resin (polycondensate of bisphenol A and phthalic acid, etc.), polycarbonate resin, polyester resin, phenoxy resin, vinyl chloride-vinyl acetate copolymer, polyamide resin, acrylic resin Insulating resin such as polyacrylamide resin, polyvinyl pyridine resin, cellulose resin, urethane resin, epoxy resin, casein, polyvinyl alcohol resin, polyvinyl pyrrolidone resin can be used, but is not limited thereto. These binder resins can be used alone or in admixture of two or more. Among these, polyvinyl acetal resin is particularly preferably used.

  In the coating solution for forming the charge generation layer, the blending ratio (mass ratio) of the charge generation material and the binder resin is preferably in the range of 10: 1 to 1:10. The solvent for preparing the coating solution may be arbitrarily selected from known organic solvents such as alcohols, aromatics, halogenated hydrocarbons, ketones, ketone alcohols, ethers, esters, and the like. it can. For example, methanol, ethanol, n-propanol, iso-propanol, n-butanol, benzyl alcohol, methyl cellosolve, ethyl cellosolve, acetone, methyl ethyl ketone, cyclohexanone, methyl acetate, ethyl acetate, n-butyl acetate, dioxane, tetrahydrofuran, Usual organic solvents such as methylene chloride, chloroform, chlorobenzene, and toluene can be used.

Moreover, the solvent used for these dispersion | distribution can be used individually or in mixture of 2 or more types. When mixing, any solvent can be used as long as it can dissolve the binder resin as the mixed solvent.
As a dispersion method, a method using a roll mill, a ball mill, a vibrating ball mill, an attritor, a sand mill, a colloid mill, a paint shaker, or the like can be used. In this dispersion, it is effective for high sensitivity and high stability that the particle size of the charge generation material particles is 0.5 μm or less, preferably 0.3 μm or less, more preferably 0.15 μm or less. is there.

  Furthermore, the charge generating material can be subjected to a surface treatment in order to improve the stability of electrical characteristics and prevent image quality defects. As the surface treatment agent, a silane coupling agent, a zirconium chelate compound, a titanium chelate compound, an aluminum chelate compound and the like can be used, but the surface treatment agent is not limited thereto. Specific examples of these include additives for the undercoat layer forming coating solution and organometallic compounds used for the intermediate layer 4.

  Furthermore, various additives can be added to the coating solution for charge generation layer in order to improve electrical characteristics and image quality. As a specific example of the additive, the additive used in the coating solution for forming the undercoat layer can be similarly used.

  As a coating method used when the charge generation layer 31 is provided, conventional methods such as a blade coating method, a wire bar coating method, a spray coating method, a dip coating method, a bead coating method, an air knife coating method, and a curtain coating method are used. Can be used.

As the charge transport material contained in the charge transport layer 32 formed on the charge generation layer, any known material can be used, but the following can be exemplified.
That is, oxadiazole derivatives such as 2,5-bis (p-diethylaminophenyl) -1,3,4-oxadiazole, 1,3,5-triphenyl-pyrazoline, 1- [pyridyl- (2)] Pyrazoline derivatives such as -3- (p-diethylaminostyryl) -5- (p-diethylaminostyryl) pyrazoline, triphenylamine, tri (p-methyl) phenylamine, N, N′-bis (3,4-dimethylphenyl) ) Aromatic tertiary amino compounds such as biphenyl-4-amine, dibenzylaniline, 9,9-dimethyl-N, N′-di (p-tolyl) fluorenon-2-amine, N, N′-diphenyl- Aromatic tertiary diamino compounds such as N, N′-bis (3-methylphenyl)-[1,1-biphenyl] -4,4′-diamine, 3- (4′-dimethylamino) 1,5,6-di- (4'-methoxyphenyl) -1,2,4-triazine, 1,2,4-triazine derivatives, 4-diethylaminobenzaldehyde-1,1-diphenylhydrazone, 4-diphenyl Hydrazone derivatives such as aminobenzaldehyde-1,1-diphenylhydrazone, [p- (diethylamino) phenyl] (1-naphthyl) phenylhydrazone, quinazoline derivatives such as 2-phenyl-4-styryl-quinazoline, 6-hydroxy-2, Benzofuran derivatives such as 3-di (p-methoxyphenyl) -benzofuran, α-stilbene derivatives such as p- (2,2-diphenylvinyl) -N, N′-diphenylaniline, enamine derivatives, N-ethylcarbazole, etc. Carbazole derivatives, poly-N-vinylcarbazole and derivatives thereof Hole transport materials such as the body,

  Quinone compounds such as chloranil, bromoanil, anthraquinone, tetracyanoquinodimethane compounds, fluorenone compounds such as 2,4,7-trinitrofluorenone, 2,4,5,7-tetranitro-9-fluorenone, 2- ( 4-biphenyl) -5- (4-t-butylphenyl) -1,3,4-oxadiazole, 2,5-bis (4-naphthyl) -1,3,4-oxadiazole, 2,5 -Oxadiazole compounds such as bis (4-diethylaminophenyl) 1,3,4 oxadiazole, xanthone compounds, thiophene compounds, 3,3 ', 5,5'-tetra-t-butyldiphenoquinone, etc. And an electron transport material such as a diphenoquinone compound, or a polymer having a group consisting of the compounds shown above in the main chain or side chain.

  These charge transport materials can be used alone or in combination of two or more. From the viewpoint of mobility, those represented by the following structural formulas (A) to (C) are preferable.

However, in the formula (A), R ¹⁴ represents a methyl group. N ′ represents an integer of 0 to 2. Ar ⁶ and Ar ⁷ represent a substituted or unsubstituted aryl group, —C (R ¹⁸ ) ═C (R ¹⁹ ) (R ²⁰ ), or —CH═CH—CH═C (Ar) ₂ , As a halogen atom, an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, or a substituted amino group substituted with an alkyl group having 1 to 3 carbon atoms. Show. Ar represents a substituted or unsubstituted aryl group, and R ¹⁸ , R ¹⁹ , and R ²⁰ represent a hydrogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aryl group.

However, in the formula (B), R ¹⁵ and R ¹⁵ ′ may be the same or different and each represents a hydrogen atom, a halogen atom, an alkyl group having 1 to 5 carbon atoms, or an alkoxy group having 1 to 5 carbon atoms. R ¹⁶ , R ¹⁶ ′, R ¹⁷ and R ¹⁷ ′ may be the same or different, and are a hydrogen atom, a halogen atom, an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, or 1 to 2 carbon atoms. An amino group substituted with an alkyl group, a substituted or unsubstituted aryl group, —C (R ¹⁸ ) ═C (R ¹⁹ ) (R ²⁰ ), or —CH═CH—CH═C (Ar ′) ₂ Represents. Incidentally, Ar 'represents a substituted or unsubstituted aryl ^{group, R 18, R 19, R} 20 represents a hydrogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aryl group. m ′ and n ″ are integers from 0 to 2.

In the formula (C), R ²¹ is a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, a substituted or unsubstituted aryl group, or,, -CH = CH-CH = C (Ar ″) ₂ is represented. Ar ″ represents a substituted or unsubstituted aryl group. R ²² and R ²³ may be the same or different, and are an amino group substituted with a hydrogen atom, a halogen atom, an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, or an alkyl group having 1 to 2 carbon atoms. Represents a group or a substituted or unsubstituted aryl group.

  Any known resin can be used as the binder resin for the charge transport layer 32, but an electrically insulating resin capable of forming a film is preferable. For example, polycarbonate resin, polyester resin, polyarylate resin, methacrylic resin, acrylic resin, polyvinyl chloride resin, polyvinylidene chloride resin, polystyrene resin, acrylonitrile-styrene copolymer, acrylonitrile-butadiene copolymer, polyvinyl acetate resin, styrene -Butadiene copolymer, vinylidene chloride-acrylonitrile copolymer, vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl acetate-maleic anhydride copolymer, silicone resin, silicone-alkyd resin, phenol-formaldehyde resin, styrene -Alkyd resin, poly-N-carbazole, polyvinyl butyral, polyvinyl formal, polysulfone, casein, gelatin, polyvinyl alcohol, ethyl cellulose, pheno Resin, polyamide, polyacrylamide, carboxymethylcellulose, vinylidene chloride polymer wax, insulating resin such as polyurethane, and polyvinylcarbazole, polyvinylanthracene, polyvinylpyrene, polysilane, JP-A-8-176293 and JP-A-8-208820 Polymer charge transport materials such as polyester-based polymer charge transport materials disclosed in Japanese Patent Publication No. Gazette can also be used.

  These binder resins can be used singly or in combination of two or more. However, polycarbonate resins, polyester resins, methacrylic resins, and acrylic resins are particularly compatible with charge transport materials, soluble in solvents, and strong. And is preferably used. The mixing ratio (mass ratio) between the binder resin and the charge transport material can be arbitrarily set in any case, but attention must be paid to a decrease in electrical characteristics and a decrease in film strength.

A polymer charge transport material can also be used alone. As the polymer charge transporting material, known materials having charge transporting properties such as poly-N-vinylcarbazole and polysilane can be used. In particular, polyester polymer charge transport materials disclosed in JP-A-8-176293 and JP-A-8-208820 have a high charge transporting property and are particularly preferable. The polymer charge transport material alone can be used as the charge transport layer, but it may be formed by mixing with the binder resin.
The blending ratio of the charge transport material and the binder resin (charge transport material: binder resin, mass ratio) is preferably in the range of 10: 1 to 1: 5.

  Further, when the charge transport layer 32 is a surface layer of the electrophotographic photosensitive member 7 (a layer disposed on the side farthest from the conductive substrate 1 of the photosensitive layer), the charge transport layer 32 imparts lubricity to the surface. In order to make the layer difficult to wear or scratch, and to improve the cleaning property of the developer adhered to the surface of the photoreceptor, lubricating particles (for example, silica particles, alumina particles, polytetrafluoroethylene (PTFE) ) -Based fluororesin particles and silicone-based resin particles). These lubricating particles can be used in combination of two or more. In particular, fluorine resin particles are preferably used.

Fluorine-based resin particles include tetrafluoroethylene resin, trifluorinated ethylene resin, hexafluoropropylene resin, vinyl fluoride resin, vinylidene fluoride resin, difluorodiethylene chloride resin and copolymers thereof. It is desirable to appropriately select one or two or more kinds from among them, and particularly preferred are tetrafluoroethylene resin and vinylidene fluoride resin.
The primary particle size of the fluororesin particles is preferably in the range of 0.05 to 1 μm, more preferably in the range of 0.1 to 0.5 μm. When the primary particle size is less than 0.05 μm, aggregation during dispersion or after dispersion tends to proceed. On the other hand, if it exceeds 1 μm, image quality defects are likely to occur.

  The content of the fluorinated resin particles in the charge transport layer 32 is suitably in the range of 0.1 to 40% by mass, particularly preferably in the range of 1 to 30% by mass, based on the total amount of the charge transport layer 32. If the content is less than 0.1% by mass, the modification effect due to the dispersion of the fluororesin particles is not sufficient. On the other hand, if the content exceeds 40% by mass, the light transmission property decreases and the residual potential increases due to repeated use. Come.

The charge transport layer 32 can be formed by applying and drying a charge transport layer forming coating solution in which a charge transport material, a binder resin, and other materials are dissolved in a suitable solvent.
Examples of the solvent used for forming the charge transport layer 32 include aromatic hydrocarbon solvents such as toluene and chlorobenzene, aliphatic alcohol solvents such as methanol, ethanol, and n-butanol, acetone, cyclohexanone, and 2-butanone. Such as ketone solvents, halogenated aliphatic hydrocarbon solvents such as methylene chloride, chloroform and ethylene chloride, cyclic or linear ether solvents such as tetrahydrofuran, dioxane, ethylene glycol and diethyl ether, or mixed solvents thereof Can be used.

Further, a slight amount of a leveling agent such as silicone oil for improving the smoothness of the coating film can be added to the coating solution for forming the charge transport layer.
As a method for dispersing the fluororesin particles in the charge transport layer 32, a roll mill, a ball mill, a vibrating ball mill, an attritor, a sand mill, a high-pressure homogenizer, an ultrasonic disperser, a colloid mill, a collision-type medialess disperser, and a penetration type A method such as a medialess disperser can be used.

Examples of the dispersion of the coating liquid for forming the charge transport layer 32 include a method in which fluorine-based resin particles are dispersed in a solution such as a binder resin or a charge transport material dissolved in a solvent.
In the step of producing a coating liquid for forming the charge transport layer 32, the temperature of the coating liquid is preferably controlled in the range of 0 ° C to 50 ° C. As a method of controlling the temperature of the coating liquid in the coating liquid manufacturing process to 0 ° C. to 50 ° C., cool with water, cool with wind, cool with refrigerant, adjust the room temperature of the manufacturing process, warm with hot water, with hot air You can use methods such as warming, heating with a heater, creating a coating liquid manufacturing facility with a material that does not easily generate heat, creating a coating liquid manufacturing facility with a material that easily dissipates heat, or creating a coating liquid manufacturing facility with a material that easily stores heat. .

  It is also effective to add a small amount of a dispersion aid in order to improve the dispersion stability of the dispersion and to prevent aggregation during the formation of the coating film. Examples of the dispersion aid include fluorine-based surfactants, fluorine-based polymers, silicone-based polymers, and silicone oils. Further, after dispersing, stirring, and mixing the fluororesin and the dispersion aid in a small amount of a dispersion solvent in advance, the mixture is dissolved and mixed with a solution obtained by mixing and dissolving the charge transport material, the binder resin, and the dispersion solvent, and then the method is performed. It is also an effective means to disperse.

The coating methods used when providing the charge transport layer 32 include dip coating, push-up coating, spray coating, roll coater coating, wire bar coating, gravure coater coating, bead coating, curtain coating, A blade coating method, an air knife coating method, or the like can be used.
The thickness of the charge transport layer 32 is preferably in the range of 5 to 50 μm, and more preferably in the range of 10 to 45 μm.

Further, the electrophotographic photoreceptor 7 of the present invention is oxidized in the photosensitive layer 3 for the purpose of preventing deterioration of the electrophotographic photoreceptor 7 due to ozone, oxidizing gas, or light / heat generated in the electrophotographic apparatus. Additives such as inhibitors and light stabilizers can be added.
For example, examples of the antioxidant include hindered phenol, hindered amine, paraphenylenediamine, arylalkane, hydroquinone, spirochroman, spiroidanone and their derivatives, organic sulfur compounds, and organic phosphorus compounds.

  Specific examples of the antioxidant include 2,6-di-tert-butyl-4-methylphenol, styrenated phenol, n-octadecyl-3- (3 ′, 5′-) for phenolic antioxidants. Di-t-butyl 4'-hydroxyphenyl) -propionate, 2,2'-methylene-bis- (4-methyl-6-t-butylphenol), 2-t-butyl-6- (3'-t-butyl) -5'-methyl-2'-hydroxybenzyl) -4-methylphenyl-acrylate, 4,4'-butylidene-bis- (3-methyl-6-tert-butylphenol), 4,4'-thio-bis- (3-methyl-6-tert-butylphenol), 1,3,5-tris (4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl) isocyanurate, tetrakis- [methylene-3- (3 ′ , 5 ' Di-tert-butyl-4′-hydroxy-phenyl) propionate] -methane, 3,9-bis [2- [3- (3-tert-butyl-4-hydroxy-5-methylphenyl) propionyloxy] -1 , 1-dimethylethyl] -2,4,8,10-tetraoxaspiro- [5,5] -undecane.

  Examples of hindered amine compounds include bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate, bis (1,2,2,6,6-pentamethyl-4-piperidyl) sebacate, 1- [2- [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionyloxy] ethyl] -4- [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionyloxy]- 2,2,6,6-tetramethylpiperidine, 8-benzyl-7,7,9,9-tetramethyl-3-octyl-1,3,8-triazaspiro [4,5] undecane-2,4-dione 4-benzoyloxy-2,2,6,6-tetramethylpiperidine, dimethyl-1- (2-hydroxyethyl) -4-hydroxy-2,2,6,6-tetramethylpiperidine succinate Polycondensate, poly [{6- (1,1,3,3-tetramethylbutyl) imino-1,3,5-triazine-2,4-diimyl} {(2,2,6,6-tetra Methyl-4-piperidyl) imino} hexamethylene {(2,3,6,6-tetramethyl-4-piperidyl) imino}], 2- (3,5-di-t-butyl-4-hydroxybenzyl) 2-n-butylmalonate bis (1,2,2,6,6-pentamethyl-4-piperidyl), N, N′-bis (3-aminopropyl) ethylenediamine-2,4-bis [N-butyl -N- (1,2,2,6,6-pentamethyl-4piperidyl) amino] -6-chloro-1,3,5-triazine condensate and the like.

  Examples of organic sulfur antioxidants include dilauryl-3,3′-thiodipropionate, dimyristyl-3,3′-thiodipropionate, distearyl-3,3′-thiodipropionate, pentaerythritol-tetrakis. -(Β-lauryl-thiopropionate), ditridecyl-3,3′-thiodipropionate, 2-mercaptobenzimidazole and the like.

Examples of the organophosphorus antioxidant include trisnonylphenyl phosfte, triphenyl phosfte, tris (2,4-di-t-butylphenyl) -phosfte and the like.
Organic sulfur-based and organic phosphorus-based antioxidants are referred to as secondary antioxidants, and a synergistic effect can be obtained by using them together with primary antioxidants such as phenols or amines.

Examples of the light stabilizer include benzophenone, benzotriazole, dithiocarbamate, and tetramethylpiperidine derivatives.
Examples of the benzophenone light stabilizer include 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-octoxybenzophenone, and 2,2′-di-hydroxy-4-methoxybenzophenone.

Examples of the benzotriazole-based light stabilizer include 2- (2′-hydroxy-5′methylphenyl) -benzotriazole, 2- [2′-hydroxy-3 ′-(3 ″, 4 ″, 5 ″, 6 ″). -Tetra-hydrophthalimido-methyl) -5'-methylphenyl] -benzotriazole, 2- (2'-hydroxy-3'-t-butyl-5'-methylphenyl) -5-chlorobenzotriazole, 2- ( 2′-hydroxy-3′-t-butyl-5′-methylphenyl) -5-chlorobenzotriazole, 2- (2′-hydroxy-3 ′, 5′-t-butylphenyl) -benzotriazole, 2- (2′-hydroxy-5′-t-octylphenyl) -benzotriazole, 2- (2′-hydroxy-3 ′, 5′-di-t-amylphenyl) -benzotriazole and the like.
Other compounds include 2,4-di-t-butylphenyl-3 ′, 5′-di-t-butyl-4′-hydroxybenzoate, nickel dibutyl-dithiocarbamate, and the like.

Further, at least one kind of electron accepting substance can be included for the purpose of improving sensitivity, reducing residual potential, reducing fatigue during repeated use, and the like.
Examples of the electron accepting substance include succinic anhydride, maleic anhydride, dibromomaleic anhydride, phthalic anhydride, tetrabromophthalic anhydride, tetracyanoethylene, tetracyanoquinodimethane, o-dinitrobenzene, m-dinitrobenzene, Examples include chloranil, dinitroanthraquinone, trinitrofluorenone, picric acid, o-nitrobenzoic acid, p-nitrobenzoic acid, and phthalic acid. Of these, fluorenone-based, quinone-based, and benzene derivatives having electron-withdrawing substituents such as Cl, CN, NO ₂ are particularly preferable.

In the electrophotographic photosensitive member 7 having a laminated structure, the protective layer 5 prevents chemical change of the charge transport layer during charging, improves the mechanical strength of the photosensitive layer, and is resistant to abrasion and scratches on the surface layer. It is used to further improve.
Examples of the form of the protective layer 5 include a cured resin film including a curable resin and a charge transporting compound, a film formed by containing a conductive material in a suitable binder resin, and the like. What is contained is more preferably used. Any known resin can be used as the curable resin, but those having a crosslinked structure are preferred from the viewpoint of strength, electrical characteristics, image quality maintenance, etc., for example, phenol resin, urethane resin, melamine resin, diallyl Examples include phthalate resins and siloxane resins.

  As the protective layer 5, the cured film formed including the compound represented by the following general formula (I-1) or (I-2) is preferable.

General formula (I-1) F- [D-Si (R ² ) _(3-a) Q _a ] _b

In general formula (I-1), F represents an organic group derived from a photofunctional compound. D represents a flexible subunit. R ² represents hydrogen, an alkyl group, or a substituted or unsubstituted aryl group. Q represents a hydrolyzable group. a represents an integer of 1 to 3. b represents an integer of 1 to 4;

General formula (I-2) F-((X) _n R ¹ -ZH) _m

In general formula (I-2), F is an organic group derived from a photofunctional compound, R ¹ is an alkylene group, Z is an oxygen atom, sulfur atom, NH, CO ₂ , or COOH, and m is 1-4. Indicates an integer. X represents oxygen or sulfur, and n represents 0 or 1.

  In general formulas (I-1) and (I-2), F is a unit having photoelectric characteristics, specifically, photocarrier transport characteristics, and a structure conventionally known as a charge transport material is used as it is. be able to. Specifically, a compound skeleton having hole transport properties such as a triarylamine compound, a benzidine compound, an arylalkane compound, an aryl-substituted ethylene compound, a stilbene compound, an anthracene compound, a hydrazone compound, and the like, and A compound skeleton having electron transport properties such as a quinone compound, a fluorenone compound, a xanthone compound, a benzophenone compound, a cyanovinyl compound, and an ethylene compound can be used.

In the general formula (I-1), -Si ( R 2) (3-a) Q a is a substituted silicon group having a hydrolyzable group, this substituted silicon group, causes a crosslinking reaction with each other by Si-base Thus, a three-dimensional Si—O—Si bond is formed. That is, this substituted silicon group plays a role of forming a so-called inorganic glassy network in the protective layer 5.

  In general formula (I-1), D represents a flexible subunit. Specifically, D is directly connected to an F site for imparting photoelectric characteristics and a three-dimensional inorganic glassy network. It represents an organic group that plays a role of linking to a substituted silicon group and imparts an appropriate flexibility to an inorganic vitreous network that is hard but brittle and improves the toughness of the film.

Specific examples _{D, -C n H 2n -,} - C n H (2n-2) -, - C n H (2n-4) - 2 divalent hydrocarbon group (here represented, n is Represents an integer of 1 to 15.) —COO—, —S—, —O—, —CH ₂ —C ₆ H ₄ —, —N═CH—, — (C ₆ H ₄ ) — (C ₆ H ₄ )-, And characteristic groups arbitrarily combining these, and those obtained by substituting the structural atoms of these characteristic groups with other substituents.

  In general formula (I-1), b is preferably 2 or more. When b is 2 or more, the photofunctional organosilicon compound represented by the general formula (I-1) contains two or more Si atoms, and it becomes easy to form an inorganic glassy network. Strength is improved.

  As the compounds represented by the general formulas (I-1) and (I-2), a compound in which the organic group F is particularly represented by the following general formula (I-3) is preferable. The compound represented by the following general formula (I-3) is a compound having a hole transporting ability (hole transporting material), and the inclusion of this in the protective layer 5 is particularly suitable for the photoelectric characteristics and mechanical properties in the protective layer 5. It is preferable from the viewpoint of improving the characteristics.

In general formula (I-3), Ar ^{1 to} Ar ⁴ each independently represents a substituted or unsubstituted aryl group. Ar ⁵ represents a substituted or unsubstituted aryl group or an arylene group. However, 2 to 4 of Ar ^{1 to} Ar ⁵ have a bond represented by —D—Si (R ² ) _(3-a) Q _a . D represents a flexible subunit. R ² represents hydrogen, an alkyl group, or a substituted or unsubstituted aryl group. Q represents a hydrolyzable group, and a represents an integer of 1 to 3.
In the general formula (I-3), specifically, Ar ^{1 to} Ar ⁵ are preferably those represented by the following formulas (I-4) to (I-10).

Here, in formulas (I-4) to (I-10), R ^{5 s} independently represent a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkyl group having 1 to 4 carbon atoms, or 1 to 1 carbon atoms. 4 represents one type selected from the group consisting of a phenyl group substituted with 4 alkoxy groups, an unsubstituted phenyl group, and an aralkyl group having 7 to 10 carbon atoms. R ⁶ represents one selected from the group consisting of a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, and a halogen atom. Further, X represents a characteristic group having a structure represented by the aforementioned _{^{-D-Si (R 2) (}} 3-a) Q a, m and s each represents 0 or 1, t is 1 to 3 Represents an integer.
In the formula (I-10), Ar is preferably represented by the following formulas (I-11) to (I-12).

In formulas (I-11) and (I-12), R ⁶ has the same meaning as R ⁶ described above. T represents an integer of 1 to 3.
In formula (I-10), Z ′ is preferably represented by the following formulas (I-13) to (I-14).

Further, as described above, wherein (I-4) ~ (I -10), X has a structure represented by the aforementioned _{^{-D-Si (R 2) (}} 3-a) Q a characteristic Represents a group. As D in the characteristic group, the divalent hydrocarbon group represented by -C ₁ H _2l- , -C _m H _{2m -2-} , -C _n H _{2n-4-described above} (where, l represents an integer of 1 to 15, m represents an integer of 2 to 15, and n represents an integer of 3 to 15), -N = CH-, -O-, -COO-, -S -,-(CH) β- (β represents an integer of 1 to 10), general formula (I-11) described above, general formula (I-12) described above, general formula (I- 13) and the characteristic group represented by (I-14).

Here, in formula (I-14), y and z each represent an integer of 1 to 5, t represents an integer of 1 to 3, and as described above, R ⁶ represents a hydrogen atom, a carbon number of 1 to 1 type chosen from the group which consists of a 4 alkyl group, a C1-C4 alkoxy group, and a halogen atom.

In general formula (I-3), Ar ⁵ represents a substituted or unsubstituted aryl group or arylene group. When k = 0, any one of formulas (I-15) to (I-19) shown in Table 4 is used. Those that fall under the above are preferred, and further those that fall under any of the formulas (I-20) to (I-24) shown in Table 5 when k = 1 are preferred.

Ar ⁵ in formula (I-3) is any one of formulas (I-15) to (I-19) shown in Table 4, and further formulas (I-20) to (I) shown in Table 5. In the case of taking any structure of −24), Z ′ in the formulas (I-19) and (I-24) is selected from the group consisting of the following general formulas (I-25) to (I-32) It is preferable that it is 1 type selected.

Here, in formulas (I-31) to (I-32), R ⁷ is selected from the group consisting of a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, and a halogen atom. 1 type is represented, W represents a bivalent group, q and r represent the integer of 1-10, respectively, and t 'represents the integer of 1-2, respectively.

  W in the formulas (I-31) and (I-32) is preferably any one of divalent groups represented by the following (I-33) to (I-41). In formula (I-40), s ′ represents an integer of 0 to 3.

—CH ₂ — (I-33)
-C (CH ₃ ) _2- (I-34)
-O- (I-35)
-S- (I-36)
-C (CF ₃ ) _2- (I-37)
—Si (CH ₃ ) ₂ — (I-38)

Moreover, as a specific example of a compound represented by general formula (I-3), the thing of the compound numbers 1-274 of Table 1-Table 55 in Unexamined-Japanese-Patent No. 2001-83728 can be used, for example.
The charge transporting compound represented by the general formula (I-1) may be used alone or in combination of two or more. In addition to the charge transporting compound represented by the general formula (I-1), a compound represented by the following general formula (II) may be used in combination for the purpose of further improving the mechanical strength of the cured film.

General formula (II) B- (Si (R ² ) _(3-a) Q _a ) ₂

In general formula (II), B represents a divalent organic group, R ² represents hydrogen, an alkyl group, or a substituted or unsubstituted aryl group, Q represents a hydrolyzable group, and a represents an integer of 1 to 3. Represent.

Examples of the compound represented by the general formula (II) include those represented by the following formulas (II-1) to (II-5), but the present invention is not limited to these. It is not a thing.
In formulas (II-1) to (II-5), T ¹ and T ² each independently represent a divalent or trivalent hydrocarbon group. It represents the substituted silicon group having hydrolyzability described above. h, i, and j each independently represent an integer of 1 to 3. The compounds represented by formulas (II-1) to (II-5) are selected so that the number of A in the molecule is 2 or more.

  Below, the preferable specific example of a compound represented by general formula (II) is shown to following formula (III-1)-(III-19). In Tables 9 and 10, Me represents a methyl group, Et represents an ethyl group, and Pr represents a propyl group.

In addition to the compounds represented by formulas (I-1) and (I-2), other compounds capable of crosslinking reaction may be used in combination. As such a compound, various silane coupling agents and commercially available silicon-based hard coat agents can be used.
As silane coupling agents, vinyltrichlorosilane, vinyltrimethoxysilane, vinyltriethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltrimethoxy Silane, γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, γ-aminopropylmethyldimethoxysilane, N-β (aminoethyl) γ-aminopropyltriethoxysilane, tetramethoxysilane, methyltrimethoxysilane, Examples include dimethyldimethoxysilane.

  As a commercially available hard coat agent, KP-85, CR-39, X-12-2208, X-40-9740, X-41-1007, KNS-5300, X-40-2239 (above, manufactured by Shin-Etsu Silicone Co., Ltd.) ), AY42-440, AY42-441, AY49-208 (manufactured by Toray Dow Corning Co., Ltd.), and the like.

  Further, a fluorine atom-containing compound can be added to the protective layer 5 for the purpose of imparting surface lubricity. By improving the surface lubricity, the coefficient of friction with the cleaning member decreases, and the wear resistance can be improved. Further, it also has an effect of preventing adhesion of discharge products, developer, paper dust, and the like to the surface of the electrophotographic photosensitive member, which is useful for improving the life of the electrophotographic photosensitive member 7.

  As a specific example of the fluorine-containing compound, a fluorine atom-containing polymer such as polytetrafluoroethylene can be added as it is, or fine particles of these polymers can be added.

Further, in the case where the protective layer 5 is a cured film formed of the compound represented by the general formula (I), a fluorine-containing compound that can react with alkoxysilane is added to constitute a part of the crosslinked film. Is desirable.
Specific examples of such fluorine atom-containing compounds include (tridecafluoro-1,1,2,2-tetrahydrooctyl) triethoxysilane, (3,3,3-trifluoropropyl) trimethoxysilane, 3- ( Heptafluoroisopropoxy) propyltriethoxysilane, 1H, 1H, 2H, 2H-perfluoroalkyltriethoxysilane, 1H, 1H, 2H, 2H-perfluorodecyltriethoxysilane, 1H, 1H, 2H, 2H-perfluoro And octyltriethoxysilane.

The addition amount of the fluorine-containing compound is preferably 20% by mass or less. Beyond this, a problem may occur in the film formability of the crosslinked cured film.
The protective layer 5 has sufficient oxidation resistance, but an antioxidant may be added for the purpose of imparting stronger oxidation resistance.

  Antioxidants are preferably hindered phenols or hindered amines, organic sulfur antioxidants, phosphite antioxidants, dithiocarbamate antioxidants, thiourea antioxidants, benzimidazole antioxidants. , Etc., may be used. The addition amount of the antioxidant is preferably 15% by mass or less, and more preferably 10% by mass or less.

  Examples of the hindered phenol antioxidant include 2,6-di-t-butyl-4-methylphenol, 2,5-di-t-butylhydroquinone, N, N′-hexamethylene bis (3,5-di). -T-butyl-4-hydroxyhydrocinnamide, 3,5-di-t-butyl-4-hydroxy-benzylphosphonate-diethyl ester, 2,4-bis [(octylthio) methyl] -o-cresol, 2,6-di-t-butyl-4-ethylphenol, 2,2'-methylenebis (4-methyl-6-t-butylphenol), 2,2'-methylenebis (4-ethyl-6-t-butylphenol) 4,4'-butylidenebis (3-methyl-6-t-butylphenol), 2,5-di-t-amylhydroquinone, 2-t-butyl-6- (3-butyl-2-hydro Xyl-5-methylbenzyl) -4-methylphenyl acrylate, 4,4′-butylidenebis (3-methyl-6-tert-butylphenol), and the like.

It is possible to add other additives used for forming a known coating film to the protective layer 5 and use known materials such as a leveling agent, an ultraviolet absorber, a light stabilizer, and a surfactant. be able to.
In order to form the protective layer 5, a mixture of the above-described various materials and various additives is applied onto the photosensitive layer and heat-treated. Thereby, a cross-linking curing reaction is caused three-dimensionally to form a strong cured film. The temperature of the heat treatment is not particularly limited as long as it does not affect the underlying photosensitive layer, but is preferably set to room temperature to 200 degrees, particularly 100 to 160 degrees.

  In the formation of the protective layer 5, the crosslinking curing reaction may be performed without a catalyst, but an appropriate catalyst may be used. Catalysts include acid catalysts such as hydrochloric acid, sulfuric acid, phosphoric acid, formic acid, acetic acid, trifluoroacetic acid, bases such as ammonia and triethylamine, organic tin compounds such as dibutyltin diacetate, dibutyltin dioctoate, stannous oxalate, Examples thereof include organic titanium compounds such as tetra-n-butyl titanate and tetraisopropyl titanate, iron salts of organic carboxylic acids, manganese salts, cobalt salts, zinc salts, zirconium salts, and aluminum chelate compounds.

  The protective layer 5 can be used by adding a solvent as required for easy application. Specifically, water, methanol, ethanol, n-propanol, i-propanol, n-butanol, benzyl alcohol, methyl cellosolve, ethyl cellosolve, acetone, methyl ethyl ketone, cyclohexanone, methyl acetate, n-butyl acetate, dioxane, tetrahydrofuran, Examples of the organic solvent include methylene chloride, chloroform, dimethyl ether, and dibutyl ether. These can be used individually by 1 type or in mixture of 2 or more types.

In the formation of the protective layer 5, as a coating method, a normal method such as a blade coating method, a Meyer bar coating method, a spray coating method, a dip coating method, a bead coating method, an air knife coating method, or a curtain coating method is used. Can do.
The thickness of the protective layer is preferably in the range of 0.5 to 20 μm, particularly in the range of 2 to 10 μm.

  In the electrophotographic photosensitive member 7, the thickness of the functional layer above the charge generation layer 31 for obtaining high resolution is preferably 50 μm or less, and more preferably 40 μm or less. When the functional layer is a thin film, the combination of the particle-dispersed undercoat layer of the present invention and a high-strength protective layer is particularly effectively used.

  The electrophotographic photoreceptor 7 is not limited to the above configuration. For example, the electrophotographic photoreceptor 7 may have a configuration in which the intermediate layer 4 and / or the protective layer 5 are not present. That is, a configuration in which the undercoat layer 2 and the photosensitive layer 3 are formed on the conductive substrate 1, and a configuration in which the undercoat layer 2, the intermediate layer 4 and the photosensitive layer 3 are sequentially formed on the conductive substrate 1. Alternatively, a structure in which the undercoat layer 2, the photosensitive layer 3, and the protective layer 5 are sequentially formed on the conductive substrate 1 may be used.

  In addition, the stacking order of the charge generation layer 31 and the charge transport layer 32 may be reversed. Further, the photosensitive layer 3 may have a single layer structure. In that case, a protective layer may be provided on the photosensitive layer, or both an undercoat layer and a protective layer may be provided. Further, the intermediate layer 4 may be provided on the undercoat layer as described above.

(Electrophotographic equipment)
FIG. 2 is a schematic view showing a preferred embodiment of the electrophotographic apparatus of the present invention.
An electrophotographic apparatus 100 shown in FIG. 2 includes a drum-shaped (cylindrical) electrophotographic photosensitive member 7 of the present invention that is rotatably provided. Around the electrophotographic photoreceptor 7, along the movement direction of the outer peripheral surface of the electrophotographic photoreceptor 7, a charging device (charging means) 8, an exposure device 10, a developing device 11, a transfer device 12, a cleaning device 13, A static eliminator (erase device) 14 is arranged in this order.

The charging device 8 is a corona charging type charging device and charges the electrophotographic photoreceptor 7. Examples of the charging device 8 include a corotron charger and a scorotron charger. The charging device 8 is connected to a power source 9.
The exposure device 10 exposes the charged electrophotographic photosensitive member 7 to form an electrostatic latent image on the electrophotographic photosensitive member 7.

The developing device 11 develops the electrostatic latent image with a developer to form a toner image. The developer preferably contains toner particles having a volume average particle diameter of 3 to 9 μm obtained by a polymerization method.
The transfer device 12 transfers the toner image developed on the electrophotographic photoreceptor 7 to a transfer medium.

The cleaning device 13 removes toner remaining on the electrophotographic photosensitive member 7 after transfer. The cleaning device 13 preferably has a blade member that comes into contact with the electrophotographic photoreceptor 7 at a linear pressure of 10 to 150 g / cm.
The static eliminator (erase device) 14 erases the remaining charges on the electrophotographic photosensitive member 7.
In addition, the electrophotographic apparatus 100 includes a fixing device 15 that fixes a toner image on a transfer medium after the transfer process.

FIG. 3 is a schematic view showing another preferred embodiment of the electrophotographic apparatus of the present invention.
The electrophotographic apparatus 110 shown in FIG. 3 has the same configuration as the electrophotographic apparatus 100 shown in FIG. 2 except that it includes a charging device 8 that charges the electrophotographic photoreceptor 7 by a contact method. In particular, in the electrophotographic apparatus 110 that employs a contact-type charging device (charging means) in which an AC voltage is superimposed on a DC voltage, the electrophotographic photoreceptor 7 can be preferably used because it has excellent leakage resistance. In this case, the static eliminator 14 may not be provided.

In the contact charging method, charging members such as a roller shape, a blade shape, a belt shape, a brush shape, and a magnetic brush shape are applicable. In particular, the roller-like or blade-like charging member may be arranged in a contact state or a non-contact state having a certain amount of gaps (100 μm or less) with respect to the electrophotographic photoreceptor 7.
A roller-shaped charging member, a blade-shaped charging member, and a belt-shaped charging member are composed of a material adjusted to an effective electrical resistance (10 ³ Ω to 10 ⁸ Ω) as a charging member, You may be comprised from several layers.

  The material is mainly composed of synthetic rubber such as urethane rubber, silicone rubber, fluorine rubber, chloroprene rubber, butadiene rubber, EPDM, epichlorohydrin rubber, and elastomers such as polyolefin, polystyrene, vinyl chloride, conductive carbon, metal oxide. In addition, an appropriate electrical conductivity imparting agent such as an ionic conductive agent may be blended in an appropriate amount to develop an effective electrical resistance as a charging member.

Furthermore, a resin such as nylon, polyester, polystyrene, polyurethane, silicone, etc. is made into a paint, and an appropriate amount of an optional conductivity imparting agent such as conductive carbon, metal oxide, or ionic conductive agent is blended therewith, and the resulting paint is dapped. It can be used by laminating by any method such as spraying or roll coating.
On the other hand, for the brush-shaped charging member, a conventional fiber-impregnated fiber such as acrylic, nylon, polyester, etc., which has been used in the past, is impregnated with fluorine, and then implanted using a conventional method. Can be produced. Further, after various fibers are formed on the brush-shaped charging member, fluorine impregnation treatment may be performed.

  The brush-shaped charging member referred to here may be any of a roller-shaped charging member and a brush-shaped charging member, and the shape thereof is not particularly limited. Further, the magnetic brush-like charging member is a member in which ferrite, magite and the like having a magnetic force are radially arranged on the outer periphery of a cylinder containing a multipolar magnet. A brush is desirable.

  FIG. 4 is a schematic view showing another preferred embodiment of the electrophotographic apparatus of the present invention. The electrophotographic apparatus 200 is a tandem type intermediate transfer type electrophotographic apparatus, and includes four electrophotographic photosensitive members 201a to 201d (for example, 201a is yellow, 201b is magenta, 201c is cyan, and 201d is black) in a housing 220. Color images can be formed respectively) along the intermediate transfer belt 209 and arranged in parallel with each other.

  Conventionally, as a method of transferring an image onto a transfer paper such as paper, there is a transfer drum method in which a transfer paper such as paper is wound around a transfer drum and a visible image on a photoconductor is transferred to the transfer paper for each color. Are known. In this case, compared to the tandem intermediate transfer method, the transfer of the visible image from the photosensitive member to the intermediate transfer member (intermediate transfer means) required the intermediate transfer member to rotate a plurality of times. Since the intermediate transfer belt 209 makes one rotation, the system can be transferred from a plurality of photoconductors 201a to 201d, and the transfer speed can be improved. Transfer system.

Here, the electrophotographic photoreceptors 201a to 201d mounted on the electrophotographic apparatus 200 are the same as the electrophotographic photoreceptor 7 respectively.
Each of the electrophotographic photoreceptors 201a to 201d can be rotated in a predetermined direction (counterclockwise on the paper surface), and the charging rolls 202a to 202d, the developing devices 204a to 204d, and the primary transfer roll 210a along the rotation direction. To 210d and cleaning devices 215a to 215d are arranged. Each of the developing devices 204a to 204d can be supplied with toner of four colors, yellow, magenta, cyan, and black, stored in the toner cartridges 205a to 205d. Further, the primary transfer rolls 210a to 210d are in contact with the electrophotographic photosensitive members 201a to 201d via the intermediate transfer belt 209, respectively.

  Further, a laser light source 203 is disposed at a predetermined position in the housing 220. Laser light emitted from the laser light source 203 can be applied to the surfaces of the electrophotographic photosensitive members 201a to 201d after charging. Accordingly, charging, exposure, development, primary transfer, and cleaning are sequentially performed in the rotation process of the electrophotographic photosensitive members 201a to 201d, and the toner images of the respective colors are transferred onto the intermediate transfer belt 209 in an overlapping manner.

  The intermediate transfer belt 209 is supported with a predetermined tension by a drive roll 206, a backup roll 208, and a tension roll 207, and can rotate without causing deflection due to the rotation of these rolls. The secondary transfer roll 213 is disposed so as to contact the backup roll 208 via the intermediate transfer belt 209. The intermediate transfer belt 209 that has passed between the backup roll 208 and the secondary transfer roll 213 is cleaned by a cleaning blade 216 disposed in the vicinity of the drive roll 206, for example, and then repeatedly used for the next image forming process. Is done.

  Further, a tray (transfer medium tray) 211 is provided at a predetermined position in the housing 220, and the transfer medium 230 such as paper in the tray 211 is transferred by the transfer roll 212 to the intermediate transfer belt 209 and the secondary transfer roll. Then, the sheet is sequentially transferred between the two fixing rolls 214 that are in contact with each other and between the two fixing rolls 214 and then discharged to the outside of the housing 220.

  In the above description, the case where the intermediate transfer belt 209 is used as the intermediate transfer member (intermediate transfer unit) has been described. However, the intermediate transfer member is belt-like (for example, an endless belt-like belt) like the intermediate transfer belt 209. Or a drum shape. When a belt-shaped configuration such as the intermediate transfer belt 209 is adopted as the intermediate transfer member, generally the film thickness of the belt is preferably in the range of 50 to 500 μm, more preferably in the range of 60 to 150 μm. In addition, the film thickness of a belt can be suitably selected according to the hardness of material. When a drum-shaped configuration is adopted as the intermediate transfer member, it is preferable to use a cylindrical substrate formed of aluminum, stainless steel (SUS), copper, or the like as the substrate. If necessary, an elastic layer can be coated on the cylindrical substrate, and a surface layer can be formed on the elastic layer.

  The medium to be transferred in the present invention is not particularly limited as long as it is a medium for transferring a toner image formed in the shape of an electrophotographic photosensitive member. For example, when transferring directly from an electrophotographic photosensitive member to paper or the like, paper or the like is a transfer medium, and when an intermediate transfer member is used, the intermediate transfer member is a transfer medium.

  As the material of the endless belt, heat such as polycarbonate resin (PC), polyvinylidene fluoride (PVDF), polyalkylene phthalate, PC / polyalkylene phthalate (PAT) blend material, ethylene tetrafluoroethylene copolymer (ETFE), etc. A semiconductive endless belt made of a plastic resin has been proposed.

Japanese Patent No. 2560727, Japanese Patent Application Laid-Open No. 5-77252, etc. propose an intermediate transfer member in which ordinary carbon black is dispersed as a conductive fine powder in a polyimide resin.
Since the polyimide resin is a material having a high Young's modulus, it is less likely to be deformed by driving (stress of a support roll, a cleaning blade, etc.), so that it becomes an intermediate transfer body in which image defects such as color misregistration are unlikely to occur. A polyimide resin is usually obtained as a polyamic acid solution by polymerizing a substantially equimolar amount of tetracarboxylic dianhydride or its derivative and a diamine in a solvent. As tetracarboxylic dianhydride, what is shown by the following general formula (IV) is mentioned, for example.

  In the above formula, R is a tetravalent group selected from the group consisting of an aliphatic chain hydrocarbon group, an aliphatic cyclic hydrocarbon group, an aromatic hydrocarbon group, and a group in which a substituent is bonded to these hydrocarbon groups. An organic group of

  Specific examples of the tetracarboxylic dianhydride include pyromellitic dianhydride, 3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride, 3,3 ′, 4,4′-biphenyltetra. Carboxylic dianhydride, 2,3,3 ′, 4-biphenyltetracarboxylic dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, 1,2,5,6-naphthalenetetracarboxylic Acid dianhydride, 1,4,5,8-naphthalenetetracarboxylic dianhydride, 2,2′-bis (3,4-dicarboxyphenyl) sulfonic acid dianhydride, perylene-3,4,9, Examples thereof include 10-tetracarboxylic dianhydride, bis (3,4-dicarboxyphenyl) ether dianhydride, and ethylenetetracarboxylic dianhydride.

On the other hand, specific examples of the diamine include 4,4′-diaminodiphenyl ether, 4,4′-diaminodiphenylmethane, 3,3′-diaminodiphenylmethane, 3,3′-dichlorobenzidine, 4,4′-diaminodiphenyl sulfide, 3,3′-diaminodiphenylsulfone, 1,5-diaminonaphthalene, m-phenylenediamine, p-phenylenediamine, 3,3′-dimethyl-4,4′-biphenyldiamine, benzidine, 3,3′-dimethylbenzidine 3,3′-dimethoxybenzidine, 4,4′-diaminodiphenylsulfone, 4,4′-diaminodiphenylpropane, 2,4-bis (β-aminotert-butyl) toluene, bis (p-β-amino- Tert-butylphenyl) ether, bis (p-β-methyl-δ-aminophenyl) benzene, bis p- (1,1-dimethyl-5-amino-benzyl) benzene, 1-isopropyl-2,4-m-phenylenediamine, m-xylylenediamine, p-xylylenediamine, di (p-aminocyclohexyl) methane , Hexamethylenediamine, heptamethylenediamine, octamethylenediamine, nonamethylenediamine, decamethylenediamine, diaminopropyltetramethylene, 3-methylheptamethylenediamine, 4,4-dimethylheptamethylenediamine, 2,11-diaminododecane, 1 , 2-bis-3-aminopropoxyethane, 2,2-dimethylpropylenediamine, 3-methoxyhexamethylenediamine, 2,5-dimethylheptamethylenediamine, 3-methylheptamethylenediamine, 5-methylnonamethylenediamine, 2, 17-diaminoeicosadecane, 1,4-diaminocyclohexane, 1,10-diamino-1,10-dimethyldecane, 12-diaminooctadecane, 2,2-bis [4- (4-aminophenoxy) phenyl] propane, _{piperazine, H 2 N (CH 2)} 3O (CH 2) 2O (CH 2) NH 2, H 2 N (CH 2) 3 S (CH 2) 3 NH 2, H 2 N (CH 2) 3 N (CH ₃ ) ₂ (CH ₂ ) ₃ NH _{2 and the} like.

  As the solvent for the polymerization reaction of tetracarboxylic dianhydride and diamine, a polar solvent is preferably used from the viewpoint of solubility. As the polar solvent, N, N-dialkylamides are preferable, and specific examples thereof include N, N-dimethylformamide, N, N-dimethylacetamide, N, N-diethylformamide, which are low molecular weight compounds thereof. N, N-diethylacetamide, N, N-dimethylmethoxyacetamide, dimethyl sulfoxide, hexamethylphosphortriamide, N-methyl-2-pyrrolidone, pyridine, tetramethylenesulfone, dimethyltetramethylenesulfone and the like. These can be used alone or in combination of two or more.

The intermediate transfer member contains oxidized carbon black in a polyimide resin. Oxidized carbon black can be obtained by oxidizing carbon black to give an oxygen-containing functional group (for example, carboxyl group, quinone group, lactone group, hydroxyl group, etc.) to the surface.
This oxidation treatment is an air oxidation method in which contact is caused to react with air in a high temperature atmosphere, a method in which it reacts with nitrogen oxide or ozone at room temperature, and a method in which ozone oxidation is performed at low temperature after air oxidation at high temperature. Etc.

  Specific examples of the oxidized carbon include MA100 (pH 3.5, volatile matter 1.5%), MA100R (pH 3.5, volatile matter 1.5%), MA100S (pH 3.5, manufactured by Mitsubishi Chemical). Volatility 1.5%), # 970 (pH 3.5, volatile content 3.0%), MA11 (pH 3.5, volatile content 2.0%), # 1000 (pH 3.5, volatile content 3) 0.02), # 2200 (pH 3.5, volatile content 3.5%), MA 230 (pH 3.0, volatile content 1.5%), MA 220 (pH 3.0, volatile content 1.0%) # 2650 (pH 3.0, volatile content 8.0%), MA7 (pH 3.0, volatile content 3.0%), MA8 (pH 3.0, volatile content 3.0%), OIL7B ( pH 3.0, volatile content 6.0%), MA 77 (pH 2.5, volatile content 3.0%), # 2350 (p 2.5, volatile content 7.5%), # 2700 (pH 2.5, volatile content 10.0%), # 2400 (pH 2.5, volatile content 9.0%); Printex made by Degussa 150T (pH 4.5, volatile content 10.0%), Special Black 350 (pH 3.5, volatile content 2.2%), Special Black 100 (pH 3.3, volatile content 2.2%), Special Black 250 (pH 3.1, volatile content 2.0%), Special Black 5 (pH 3.0, volatile content 15.0%), Special Black 4 (pH 3.0, volatile content 14.0%), Special Black 4A (pH 3.0, volatile content 14.0%), Special Black 550 (pH 2.8, volatile content 2.5%), Special Black 6 (pH 2.5, volatile content 18.0%), Same color black FW2 0 (pH 2.5, volatile content 20.0%), same color black FW2 (pH 2.5, volatile content 16.5%), same color black FW2V (pH 2.5, volatile content 16.5%); Cabot Corporation MONARCH1000 (pH 2.5, volatile content 9.5%), MONARCH 1300 (pH 2.5, volatile content 9.5%) manufactured by Cabot, MONARCH 1400 (pH 2.5, volatile content 9.0%) manufactured by Cabot, MOGUL-L (pH 2.5, volatile matter 5.0%), REGAL400R (pH 4.0, volatile matter 3.5%);

The oxidation-treated carbon black obtained in this way has an excessive current flowing in part, and is not easily affected by oxidation due to repeated voltage application. Furthermore, due to the effect of the oxygen-containing functional group attached to the surface, the dispersibility in polyimide is high, the resistance variation can be reduced, the electric field dependency is also reduced, and the electric field concentration due to the transfer voltage is less likely to occur. .
As a result, resistance degradation due to transfer voltage is prevented, uniformity of electrical resistance is improved, electric field dependency is small, resistance change due to the environment is small, and image quality defects such as whitening of the paper running part occur. The intermediate transfer member can obtain a suppressed high image quality. If at least two types are included, these oxidized carbon blacks preferably have substantially different conductivity, such as the degree of oxidation treatment, DBP oil absorption, specific surface area by the BET method using nitrogen adsorption, etc. Use materials with different physical properties.

When two or more types of carbon blacks having different physical properties are added as described above, for example, carbon black exhibiting high conductivity is preferentially added, and then carbon black having low conductivity is added to adjust the surface resistivity. It is possible.
Specific examples of the oxidized carbon black include SPECIAL BLACK4 (Degussa, pH 3.0, volatile content: 14.0%), SPECIAL BLACK250 (Degussa, pH 3.1, volatile content: 2.0%), and the like. Is mentioned. The content of these oxidized carbon blacks is preferably about 10 to 50% by mass, more preferably 12 to 30% by mass with respect to the polyimide resin. If this content is less than 10% by mass, the uniformity of electrical resistance may be reduced, and the decrease in surface resistivity during durable use may increase. On the other hand, if it exceeds 50% by mass, the desired resistance value may be obtained. Is not preferred, and it is not preferable because it becomes brittle as a molded product.

The intermediate transfer body made of polyimide resin in which oxidized carbon black is dispersed performs a step of preparing a polyamic acid solution in which oxidized carbon black is dispersed, a step of forming a film (layer) on the inner surface of a cylindrical mold, and imide conversion It can be obtained through a process.
About the manufacturing method of the polyamic acid solution which disperse | distributed 2 or more types of oxidation treatment carbon black, the said acid dianhydride component and diamine component are contained in the dispersion liquid which disperse | distributed 2 or more types of oxidation treatment carbon black beforehand in the solvent. Method of dissolving and polymerizing Two or more types of oxidized carbon black are each dispersed in a solvent to prepare two or more types of carbon black dispersions, and the acid anhydride component and the diamine component are dissolved and polymerized in this dispersion. Thereafter, a method of mixing each polyamic acid solution, etc. can be considered, and a polyamic acid solution in which carbon black is dispersed is prepared by selecting as appropriate.

  The polyamic acid solution thus obtained is supplied to and spread on the inner surface of the cylindrical mold to form a film, and the polyamic acid is obtained by imide conversion by heating. In this heating step for imide conversion, an intermediate transfer member having good flatness can be obtained by performing imide conversion under heating conditions that are maintained at a constant temperature for 0.5 hour or more. This will be described in detail below.

A polyamic acid solution is supplied to the inner surface of the cylindrical mold. This supply method can be performed by appropriately selecting a method using a dispenser, a method using a die, or the like. The surface state of the inner peripheral surface of the cylindrical mold used at this time is preferably mirror-finished.
A coating film having a uniform film thickness is formed by appropriately selecting the polyamide acid solution supplied in this manner, such as a method of centrifugal molding while heating, a method of molding using a bullet-shaped traveling body, a method of rotational molding, and the like. Subsequently, the mold with the coating film formed on the inner peripheral surface is heated in a dryer and heated until imide conversion, or after removing the solvent until the shape can be maintained as a belt, from the inner surface of the mold A method may be considered in which, after peeling and replacing the outer surface of a metal cylinder, the entire cylinder is heated to perform imide conversion. In order to obtain an intermediate transfer member having suitable flatness and outer surface accuracy, it is preferable to remove the solvent until it can be held as a belt, and then replace it with a metal cylinder to perform imide conversion.

The heating conditions in the step of removing the solvent are not particularly limited as long as the removal of the solvent proceeds, but preferably at 80 to 200 ° C. for 0.5 to 5 hours. Next, the molded product that can retain its shape as a belt is peeled off from the inner peripheral surface of the mold. At this time, a mold release process can be performed on the inner peripheral surface of the mold.
Next, the molded product heated and cured until it can be held as a belt shape is replaced with the outer surface of the metal cylinder, and the replaced cylinder is heated to advance the imide conversion reaction of the polyamic acid.
The metal cylinder used at this time preferably has a linear expansion coefficient larger than that of the polyimide resin. By making the outer diameter of the cylinder smaller than the inner diameter of the polyimide molding by a predetermined amount, heat setting can be performed and a uniform film thickness can be obtained. Thus, an endless belt without unevenness can be obtained. The surface roughness (Ra) of the outer surface of the metal cylinder used at this time is preferably 1.2 to 2.0 μm. If the surface roughness (Ra) of the outer surface of the metal cylinder is smaller than 1.2 μm, the belt-shaped intermediate transfer member obtained because the metal cylinder itself is too smooth will not slip due to contraction in the axial direction of the belt. This is performed in this step, which causes variations in film thickness and a decrease in flatness accuracy.

  Also, if the surface roughness (Ra) of the outer surface of the metal cylinder is larger than 2.0 μm, the outer surface of the metal cylinder is transferred to the inner surface of the belt-shaped intermediate transfer member, and unevenness is generated on the outer surface, thereby causing image defects. generate. The surface roughness (Ra) of the outer surface of the belt-shaped intermediate transfer member made of polyimide resin in which carbon black thus obtained is dispersed is 1.5 μm or less.

  The surface roughness is measured according to JIS B601. When the surface roughness (Ra) of the intermediate transfer member is larger than 1.5 μm, image defects such as roughness occur. The reason for this is that when the voltage applied locally during transfer or the electric field due to the stripping discharge is concentrated on the convex part of the belt surface, the surface of this part is altered and a new conductive path is created, resulting in a decrease in resistance. However, the density is lowered, and it seems that the entire image looks cluttered.

  It is preferable that the heating process for imide conversion is performed at a heating temperature of 220 to 280 ° C. and a heating time of 0.5 to 2 hours. Although depending on the composition of the polyimide resin, the amount of shrinkage is the largest in this region under the heating conditions during imide conversion.Thus, by gently performing the shrinkage in the axial direction of the belt, film thickness variation and flatness A reduction in accuracy can be prevented.

  The intermediate transfer member that has undergone such a heating step has a flatness of 5 mm or less, preferably 3 mm or less. When the flatness is 5 mm or less, there is no roughness and color deviation is small. However, when the belt end is bent vertically, the intermediate transfer member will not break during use even if it is 5 mm or less, but it rarely remains after contacting the peripheral member. Further, when the flatness is 3 mm or less, the intermediate transfer member is not brought into contact with the peripheral member during use and there is almost no color shift.

(Electrophotographic cartridge)
Next, an electrophotographic cartridge (process cartridge) equipped with the electrophotographic photosensitive member of the present invention will be described.

FIG. 5 is a schematic view showing a preferred embodiment of the electrophotographic cartridge of the present invention.
In the process cartridge 300, a charging device (charging means) 308, a developing device 311, a cleaning device 313, and a static eliminator 314 are combined and integrated in a case 301 using an attachment rail 303 together with an electrophotographic photosensitive member 307. . The process cartridge 300 is not provided with an exposure device, but an opening 305 for exposure is formed in the case 301. The electrophotographic photoreceptor 307 is the above-described electrophotographic photoreceptor of the present invention, which has at least an undercoat layer and a photosensitive layer on a conductive substrate, and the undercoat layer is dispersed as a solid material. An electrophotographic photoreceptor 307 containing an acceptor compound in a state and metal oxide particles.

  The process cartridge 300 is detachable from an electrophotographic apparatus main body including a transfer device 312, a fixing device 315, and other components not shown, and constitutes the electrophotographic apparatus together with the electrophotographic apparatus main body. To do.

EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited by these Examples.
<Example 1>
100 parts by mass of zinc oxide (volume average particle size: 70 nm, manufactured by Teica, specific surface area value: 15 m ² / g) is stirred and mixed with 500 parts by mass of tetrahydrofuran, and a silane coupling agent (KBM603, manufactured by Shin-Etsu Chemical Co., Ltd.) 25 parts by mass was added and stirred for 2 hours. Tetrahydrofuran was then distilled off under reduced pressure and baked at 120 ° C. for 3 hours to obtain a silane coupling agent surface-treated zinc oxide pigment.

  60 parts by mass of the surface-treated zinc oxide particles, 0.3 parts by mass of alizarin, 13.5 parts by mass of blocked isocyanate (Sumidule 3173, manufactured by Sumitomo Bayern Urethane Co., Ltd.) as a curing agent, and butyral resin (BM -1, 10 parts by mass of Sekisui Chemical Co., Ltd.) was dissolved in a mixed solvent of 72 parts by mass of methyl ethyl ketone and 18 parts by mass of n-hexane, and 57 parts by mass of this solution was a sand mill (glass) using glass beads having a diameter of 1 mm. A dispersion was obtained by dispersing for 2 hours at a bead filling ratio of 80%.

  Dioctyltin dilaurate: 0.005 parts by mass and silicone resin particles (Tospearl 145, manufactured by GE Toshiba Silicone): 4.0 parts by mass are added to 100 parts by mass of the resulting dispersion as an undercoat layer. A coating solution was obtained. This coating solution was applied onto an aluminum substrate by a dip coating method, followed by drying and curing at 170 ° C. for 40 minutes to obtain an undercoat layer having a thickness of 25 μm.

  When the above undercoat layer-forming coating solution was separately applied to a PET base and the dried undercoat layer was observed with an optical microscope (200 times), a large number of granular alizarin particles (solid matter) were found. As a result of measuring the maximum length as described above, the maximum length was 1 to 2 μm. In the undercoat layer, a large number of the alizarin particles were observed around the zinc oxide particles (aggregates).

  Next, a photosensitive layer was formed on the undercoat layer. First, the Bragg angle (2θ ± 0.2 °) of an X-ray diffraction spectrum using CuKα rays as a charge generating material is at least 7.3 °, 16.0 °, 24.9 °, 28.0 °. A mixture comprising 15 parts by mass of hydroxygallium phthalocyanine having a diffraction peak at a position, 10 parts by mass of vinyl chloride / vinyl acetate copolymer resin (VMCH, manufactured by Nihon Unicar) as a binder resin and 200 parts of n-butyl acetate, The dispersion was carried out for 4 hours by a sand mill using glass beads having a diameter of 1 mm.

  To the obtained dispersion, 175 parts by mass of n-butyl acetate and 180 parts by mass of methyl ethyl ketone were added and stirred to obtain a coating solution for a charge generation layer. This charge generation layer coating solution was dip-coated on the undercoat layer and dried at room temperature to form a charge generation layer having a thickness of 0.2 μm.

  Next, 1 part by mass of tetrafluoroethylene resin particles (volume average particle size: 0.2 μm) and 0.02 part by mass of the fluorine-based graft polymer were sufficiently stirred and mixed together with 5 parts by mass of tetrahydrofuran and 2 parts by mass of toluene. A suspension of fluoroethylene resin particles was obtained. Next, 4 parts by mass of N, N′-diphenyl-N, N′-bis (3-methylphenyl)-[1,1 ′] biphenyl-4,4′-diamine as a charge transport material, and a bisphenol Z-type polycarbonate 6 parts by mass of a resin (viscosity average molecular weight: 40,000) was mixed and dissolved in 23 parts by mass of tetrahydrofuran and 10 parts by mass of toluene.

After adding 8.02 parts by mass of the tetrafluoroethylene resin particle suspension to this and stirring and mixing, a high-pressure homogenizer (trade name LA-33S, manufactured by Nanomizer Co., Ltd.) equipped with a through-type chamber having fine dew. Was used, and the dispersion treatment with the pressure increased to 3923 N / cm ² (400 kgf / cm ² ) was repeated 6 times, and 0.2 parts by mass of 2,6-di-t-butyl-4-methylphenol was further mixed. Thus, a coating liquid for forming a charge transport layer was obtained. This coating solution was applied onto the charge generation layer and dried at 115 ° C. for 40 minutes to form a charge transport layer having a thickness of 32 μm, whereby an electrophotographic photosensitive member (1) was obtained.

  The electrophotographic photosensitive member (1) thus obtained is mounted on a full color printer Docu Center Color C400 manufactured by Fuji Xerox Co., which has a contact charging device and an intermediate transfer device, and is subjected to high temperature and high humidity (28 ° C., 85% RH). ) And low-temperature and low-humidity (15 ° C., 10% RH), the image quality and cycle characteristics after initial and continuous 10,000-sheet printing were examined, respectively.

(ghost)
For the ghost evaluation image, an arbitrary number of 15 mm square patterns are printed for one round of the electrophotographic photosensitive member, and then the entire halftone image is printed in the next cycle, and the ghost image that appears on the halftone image is displayed. evaluated. Magenta was used for printing. The halftone image was created with a pattern of 1 dot ON-3 dots OFF.

Evaluation was made according to the following criteria, using the result of Comparative Example 1 as a standard.
○: Ghost occurrence is significantly improved compared to the standard.
Δ: Ghost is equivalent or slightly worse than standard.
X: Ghost is worse than standard.

(Cover, sunspot)
In the same manner, the result of Comparative Example 1 was used as a standard, and evaluation was performed according to the following criteria.
○: Compared to the standard, the sunspot is considerably improved.
Δ: Fog compared to the standard, black spots are equivalent or slightly bad.
X: It is fogging and black spots are worse than the standard.

(Cycle characteristics)
In the same manner, the result of Comparative Example 1 was used as a standard, and evaluation was performed according to the following criteria.
○: Residual potential rise is considerably improved compared to the standard.
Δ: Residual potential rise is equivalent or slightly worse than standard.
X: Increase in residual potential is worse than standard.
The results are summarized in Table 11.

<Examples 2-3>
In Example 1, an electrophotographic photosensitive member was produced in the same manner as in Example 1 except that the solvent of the coating solution for forming the undercoat layer was changed to the solvent and composition shown in Table 1, and the characteristics were similarly evaluated. The results are shown in Table 11.

<Example 4>
In Example 1, an electrophotographic photosensitive member was prepared in the same manner as in Example 1 except that the coating solution for forming the undercoat layer was dispersed without alizarin and added with alizarin 20 minutes before the end of dispersion for 2 hours. It produced and evaluated the characteristic similarly. The results are shown in Table 11.

<Comparative Examples 1-2>
In Example 1, an electrophotographic photosensitive member was produced in the same manner as in Example 1 except that the solvent of the coating solution for forming the undercoat layer was changed to the solvent and composition shown in Table 1, and the characteristics were similarly evaluated. In the comparative example, the acceptor compound solid was not observed in the undercoat layer under a microscope.
The results are shown in Table 11.

  As shown in Table 11, when the electrophotographic photosensitive member of the present invention of the example is used, it can be seen that generation of ghosts and cycle up are considerably improved as compared with Comparative Example 1.

1 is a schematic cross-sectional view showing an example of an electrophotographic photosensitive member of the present invention. It is a schematic diagram which shows an example of the electrophotographic apparatus of this invention. It is a schematic diagram which shows another example of the electrophotographic apparatus of this invention. It is a schematic diagram which shows another example of the electrophotographic apparatus of this invention. It is a schematic diagram showing an example of the electrophotographic cartridge of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Conductive substrate 2 Undercoat layer 3 Photosensitive layer 4 Intermediate layer 5 Protective layer 7, 201, 307 Electrophotographic photosensitive member 8, 8 ', 308 Charging device (charging means)
DESCRIPTION OF SYMBOLS 10 Exposure device 11, 204, 311 Developing device 12, 312 Transfer device 13, 215, 313 Cleaning device 14, 314 Charger 31 Charge generation layer 32 Charge transport layer 100, 110, 200 Electrophotographic device 209 Intermediate transfer belt (intermediate transfer belt) means)
210 Primary transfer roll 213 Secondary transfer roll 214 Fixing roll 300 Electrophotographic cartridge 301 Case 303 Mounting rail 305 Opening

Claims (6)

In an electrophotographic photosensitive member having at least an undercoat layer and a photosensitive layer on a conductive substrate, the undercoat layer contains an acceptor compound containing an anthraquinone structure having a hydroxyl group in a dispersed state as a solid. An electrophotographic photoreceptor.   The electrophotographic photosensitive member according to claim 1, wherein the maximum length of the solid matter is 10 μm or less.   The electrophotographic photosensitive member according to claim 1, wherein the undercoat layer contains metal oxide fine particles in addition to the acceptor compound.   The undercoat layer is obtained by applying a coating solution in which the acceptor compound is dispersed in a solvent containing a nonpolar solvent to the conductive substrate and drying the coating solution. The electrophotographic photosensitive member according to any one of 1 to 3. An electrophotographic cartridge comprising at least the electrophotographic photosensitive member according to any one of claims 1 to 4 and charging means for charging the electrophotographic photosensitive member. The claims 1 to electrophotographic photosensitive member according to any one of 4, an electrophotographic apparatus, comprising a charging means for charging the electrophotographic photosensitive member, at least.

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