JP2015108730A - Electrophotographic photoreceptor, image forming apparatus, and process cartridge - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrophotographic photoreceptor that can provide stable electrical characteristics even after a long-term use, and suppress afterimages and scumming during image formation.SOLUTION: There is provided an electrophotographic photoreceptor having at least a support, and an undercoat layer and a photosensitive layer on the support in this order, where the undercoat layer contains at least gallium-containing zinc oxide particles and a binder resin, and the undercoat layer has a specular reflectivity to incident light with a wavelength of 800 nm of 70% or more.

Description

  The present invention relates to an electrophotographic photosensitive member, an image forming apparatus using the electrophotographic photosensitive member, and a process cartridge.

In an image forming method using an image forming apparatus, an image is formed by subjecting a photoconductor to steps such as a charging step, an exposure step, a development step, and a transfer step. In recent years, organic photoreceptors using organic materials have been widely used as electrophotographic photoreceptors (hereinafter also referred to as “photoreceptors”) because of their advantages in flexibility, thermal stability, film formability, and the like. Yes.
Along with the rapid progress of full color, high speed, and high definition in recent image forming apparatuses, there is a demand for further durability and high stability of the photoreceptor. Improvements have dramatically improved the wear resistance of the photoreceptor. On the other hand, electrical and chemical durability is required for each layer constituting the inside of the photoreceptor such as the photosensitive layer, the intermediate layer, and the undercoat layer.

  The organic material constituting the photoconductor gradually changes in quality due to the electrostatic load in the current electrophotographic process in which charging and discharging are repeated. As a result, the electrical characteristics of the photosensitive member deteriorate, and the electrical stability in long-term use cannot be maintained. In particular, a decrease in chargeability has a large effect on the image quality of the output image, and a decrease in image density, background contamination (hereinafter also referred to as “background contamination”, “fogging”, and “black spot”), during continuous output It is known to cause serious problems such as image homogeneity. It is thought that this is largely due to the undercoat layer of the photoreceptor, and improvement of the undercoat layer is necessary for durability and high stability of the photoreceptor in the future.

  In general, the organic photoreceptor is composed of a conductive support made of aluminum or the like, an undercoat layer formed on the support, and a photosensitive layer laminated on the undercoat layer. The undercoat layer is a conductive layer mainly containing conductive particles such as a binder resin and metal oxide particles, and has a leak-proof function due to concealment of the support surface and “charge injection from the support to the photosensitive layer. It is provided for the three purposes of “blocking function” and “charge transport function” of charges generated in the photosensitive layer to the support, and it is required to improve these functions.

As a conventional undercoat layer, an undercoat layer using titanium oxide particles has been proposed. The thickness is about 1 μm to several μm, and the leak resistance function due to the concealment of the support is insufficient. Further, the content of titanium oxide particles is about 80% by mass of the undercoat layer, and since the content of titanium oxide particles is large, the dispersibility of the titanium oxide particles in the film cannot be maintained, and the undercoat layer is fine. Leak points due to cracks and the like are generated. As a result, there is a problem that abnormal images are generated due to soiling during long-term use (see Patent Document 1).
On the other hand, a method of providing a leak-proof function by using an intermediate layer on the undercoat layer has been proposed (see Patent Document 2). However, this proposal has a problem that the photoreceptor function cannot be sufficiently maintained, for example, the charge accumulation increases as the layer interface increases.
Further, an undercoat layer using tin oxide particles or zinc oxide particles has been proposed (see Patent Document 3). The proposed undercoat layer has a thickness of several tens of μm and can be made thicker while controlling the volume resistance of the undercoat layer. However, the thicker layer improves leakage resistance and stabilizes electrical characteristics. In addition, it is not possible to obtain an undercoat layer that can satisfy all the characteristic values required for an electrophotographic photosensitive member such as fog.
On the other hand, an additive is added to the undercoat layer using zinc oxide to improve the dispersibility so that the electrical stability over a long period of time can be maintained, and the transmittance for light with a wavelength of 950 nm is 85% A method has been proposed (see Patent Documents 4 and 5).
However, these proposals cannot maintain a sufficient leak-proof function and electrical characteristics during long-term use. This is presumably because charges accumulated in the undercoat layer or near the interface between the undercoat layer and the upper layer during repeated use over a long period of time.

  On the other hand, a method has been proposed in which tin oxide particles containing antimony or phosphorus and zinc oxide particles containing aluminum or gallium are used as metal oxide particles containing foreign elements in the undercoat layer (see Patent Document 6). However, this proposal has a problem that a sufficient leak-proof function cannot be maintained during long-term use.

  Therefore, all of the prior art documents have an undercoat layer that can satisfy all the functions of the anti-leakage function, the charge injection blocking function, and the charge transport function required for the undercoat layer when used for a long time. Even so, there is currently no electrophotographic photoreceptor that can provide stable electrical characteristics and can suppress afterimages and background contamination during image formation.

  An object of the present invention is to solve the conventional problems and achieve the following objects. That is, an object of the present invention is to provide an electrophotographic photosensitive member that can obtain stable electrical characteristics even when used for a long period of time, and can suppress afterimages and background stains during image formation. To do.

The electrophotographic photosensitive member of the present invention as a means for solving the above problems is an electrophotographic photosensitive member having at least a support and an undercoat layer and a photosensitive layer in this order on the support,
The undercoat layer contains at least gallium-containing zinc oxide particles and a binder resin;
The specular reflectance of the undercoat layer with respect to incident light having a wavelength of 800 nm is 70% or more.

  According to the present invention, the conventional problems can be solved, stable electrical characteristics can be obtained even when used for a long period of time, and afterimages and background stains can be suppressed during image formation. An electrophotographic photosensitive member can be provided.

FIG. 1 is a schematic view showing an example of the layer structure of the electrophotographic photosensitive member of the present invention. FIG. 2 is a schematic view showing an example of the layer structure of the electrophotographic photosensitive member of the present invention. FIG. 3 is a schematic view showing an example of the layer structure of the electrophotographic photosensitive member of the present invention. FIG. 4 is a schematic view showing an example of the layer structure of the electrophotographic photosensitive member of the present invention. FIG. 5 is a schematic view showing an example of the image forming apparatus of the present invention. FIG. 6 is a schematic view showing an example of the process cartridge of the present invention. FIG. 7 is an X-ray diffraction spectrum diagram of titanyl phthalocyanine used as a charge generation material in Examples, where the vertical axis represents the counts per second (cps: counts per second), and the horizontal axis represents the angle (2θ). Represents.

(Electrophotographic photoreceptor)
The electrophotographic photosensitive member of the present invention has at least an undercoat layer and a photosensitive layer in this order on a conductive support and the conductive support, and further has other layers as necessary. Become.
The electrophotographic photosensitive member of the present invention has the material defined in the present invention in the undercoat layer, and the conductive support, the photosensitive layer, and the other layers are the same as those in the past. Can be applied.

<Underlayer>
The undercoat layer contains at least gallium-containing zinc oxide particles and a binder resin, and further contains other components as necessary.

As the undercoat layer of the photosensitive member, the conductive support is completely hidden by a homogeneous film (leak resistance function), and unnecessary charges from the conductive support to the photosensitive layer (charging of the photosensitive member). A function that suppresses injection of charges of opposite polarity) (a charge injection blocking function), and a function that transports charges of the same polarity as the charge polarity of the photoreceptor among the charges formed in the photosensitive layer (charge transport function) In order to obtain a long-term stable photoreceptor, it is important that these characteristics do not change even with repeated electrostatic loads.
On the other hand, as a result of intensive studies by the present inventors, these characteristics are as follows: the undercoat layer contains at least gallium-containing zinc oxide particles and a binder resin, and the specular reflectance with respect to incident light having a wavelength of 800 nm. It has been found that this can be achieved by 70% or more.

The reason why all the functions necessary for the undercoat layer are satisfied by the present invention is not clear, but the following can be considered.
Gallium-containing zinc oxide particles are very low-resistance particles compared to other metal oxide particles, and exhibit excellent electrical characteristics in the undercoat layer. Thereby, it is considered that the undercoat layer can obtain a sufficient charge injection blocking function and a charge transport function. Furthermore, since the gallium-containing zinc oxide particles have a low resistance, they can exhibit their functions with a smaller amount of addition than when other metal oxide particles are used. Thereby, it is considered that the undercoat layer can form a very homogeneous dispersion state without fine cracks, and a sufficient leak-proof function can be obtained.

It is important that the undercoat layer is a dispersion film in which gallium-containing zinc oxide particles are uniformly dispersed. If aggregates of gallium-containing zinc oxide particles are present in the undercoat layer, these aggregates become local leak points, which may cause abnormal images such as dirt, and charge traps occur in the aggregates. It may be a cause of an abnormal image such as an afterimage caused by an increase in the residual potential.
The dispersibility of the gallium-containing zinc oxide particles in the undercoat layer can be confirmed by specular reflectivity. If the specular reflectivity of the undercoat layer with respect to light having a wavelength of 800 nm is 70% or more, it is sufficiently dispersed. You can say that. The specular reflectance is 70% or more, preferably 80% or more.
When measuring the specular reflectance, if light having a wavelength shorter than 800 nm is used, stable measurement may not be possible due to the additive used for the undercoat layer or the surface treatment agent for the gallium-containing zinc oxide particles. In addition, when light having a wavelength longer than 800 nm is used, scattering due to small particle diameters affects the measurement, and stable measurement may not be possible. In order to confirm the dispersibility of the gallium-containing zinc oxide particles in the undercoat layer, it is necessary to measure the specular reflectance using light having a wavelength of 800 nm.

The specular reflectance is prepared by, for example, preparing a sample in which the charge generation layer and the charge transport layer are dissolved or peeled using a solvent and only the undercoat layer is laminated on the support. Each layer can be dissolved or peeled off by wiping the charge generation layer with a soft cloth (cotton) moistened with tetrahydrofuran, and immersing the charge transport layer in 2-butanone for a predetermined time.
A spectrophotometer UV-3600 (Shimadzu Co., Ltd.) equipped with a multipurpose large sample chamber unit MPC-3100 (manufactured by Shimadzu Corporation) was used for the sample in which only the obtained undercoat layer was laminated on the support. Can be used to measure the specular reflectance of the undercoat layer when the incident light has a wavelength of 800 nm and the incident light is 8 °.
Cut the sample with only the support layer and the undercoat layer stacked on the support layer to an appropriate size. First, set the support layer with nothing stacked on the measuring device. After performing the line correction, the specular reflectance can be measured by setting a sample in which only the undercoat layer is laminated on the support in a measuring device.

<< Gallium-containing zinc oxide particles >>
The gallium-containing zinc oxide particles in the present invention are produced, for example, as follows.
(1) A method in which an aqueous slurry to which zinc oxide and a gallium salt are added is aged while hydrolyzing, and then the produced precipitate is separated and the resulting product (cake) is baked. In this case, it is good to use together the material (erosion agent or etching agent) which corrodes zinc oxide.
(2) A method in which a mixed solution of a lead salt or zinc oxide precursor and gallium alone or a gallium salt is hydrolyzed, the produced precipitate is separated, and the resulting product (cake) is baked. The zinc oxide in the present invention may be any so-called zinc oxide. For example, the French method in which zinc is melted and evaporated and oxidized in the gas phase, the American method in which zinc ore is calcined, coke reduced, and oxidized, soda ash is added to a zinc salt solution to precipitate basic zinc carbonate, and then dried -What was manufactured by any of the wet methods (thermal decomposition method) etc. which calcinate may be used.

  Examples of the gallium salt include gallium sulfate, gallium chloride, gallium bromide, gallium hydroxide, and gallium nitrate. These may be used as they are, or may be dissolved in water or an appropriately diluted acid, or may be dissolved in water-soluble alcohols.

Examples of the erodant include ammonium carbonate, ammonium bicarbonate, ammonium nitrate, and ammonium sulfate.
Examples of the zinc salt include inorganic salts such as halides such as zinc hydroxide, carbonate, nitrate, sulfate, chloride, fluoride, acetate, propionate, butyrate, laurate, etc. Examples thereof include carboxylates, metal alkoxides, β-diketones, hydroxycarboxylic acids, ketoesters, ketoalcohols, aminoalcohols, glycols, quinoline and metal chelate compounds.

  In the production methods (1) and (2) above, the following water-soluble organic substances may coexist. Here, the water-soluble organic substances are amine acids, amines, alcohols, polyols, phenols, ketones, polyethers, esters, carboxylic acids, polycarboxylic acids, celluloses, saccharides, ureas, sulfonic acids. For example, hydroxyamines such as monoethanolamine, diethanolamine, triethanolamine, butanolamine, amino acids such as glycine, glutamic acid, aspartic acid, alanine, trimethylaminoethylalkylamide, alkylpyridinium sulfate, alkyltrimethyl C1-C6 aliphatic alcohol such as ammonium halide, alkylbetaine, alkyldiethylenetriaminoacetic acid, methanol, ethanol, propanol, butanol, pentanol, hexanol, propane Phenols or catechols having no substituent such as aliphatic polyhydric alcohols such as all, butanediol, ethylene glycol, glycerin, polyethylene glycol, etc., phenol, catechol, cresol, etc. Alcohols having a heterocyclic ring such as furyl alcohol, ketones having 1 to 6 carbon atoms such as acetone, acetylacetone, methyl ethyl ketone, and lactone, ethyl ether, tetrahydrofuran, dioxane, polyoxyethylene alkyl ether, ethylene oxide adduct, propylene oxide addition Ethers or polyethers, etc., esters such as ethyl acetate, ethyl acetoacetate, glycine ethyl ester, formic acid, acetic acid, succinic acid, citric acid, tartaric acid, salicylic acid, benzoic acid, malonic acid, alcohol Carboxylic acids such as lauric acid, maleic acid, succinic acid, propionic acid, glyceric acid, eleostearic acid, polyacrylic acid, polymaleic acid, acrylic acid-maleic acid copolymer, polycarboxylic acid or hydroxycarboxylic acid or hydrochloric acid thereof, carboxy Monosaccharides such as methylcellulose, glucose, galactose, polysaccharides such as sucrose, lactose, amylose, chitin, cellulose, ureas such as urea, acetylurea, alkylbenzenesulfonic acid, paratoluenesulfonic acid, alkylsulfonic acid, α-olefin Examples thereof include sulfonic acids such as sulfonic acid, polyoxyethylene alkyl sulfonic acid, lignin sulfonic acid, and naphthalene sulfonic acid, or salts thereof.

Examples of the method for separating the precipitate from the aqueous slurry or mixed solution include a method of dehydrating by solid-liquid separation means such as filtration and centrifugation.
Furthermore, as the gallium-containing zinc oxide particles used in the present invention, it is more preferable to contain a sintering preventing component having a sintering preventing effect on the surface of the zinc oxide particles. By containing an anti-sintering component, extreme particle growth can be suppressed at the time of particle production, and inorganic fine particles with little variation in particle size can be obtained, and firing at a relatively high temperature is possible. Further, it has a feature that the diffusion of the contained element in the inorganic fine particles can be easily leveled. In addition, by selecting a sintering inhibitor having a sintering temperature higher than that of the main constituent element of the inorganic fine particles, the inorganic fine particles are less likely to coalesce and agglomerate during the firing of the inorganic fine particles. When applied to the use of forming a coating film using a similar liquid dispersion, it has a feature that it is easy to obtain a coating film in which inorganic fine particles are well dispersed.

The sintering preventing component is, for example, a compound of at least one element selected from Si, Zr, Mg, Hf, Sn, Sr, Mo, W, Ge, Nb, V, Ca, Ta, and Ba. Preferably, the sintering inhibitor having a higher sintering temperature than zinc oxide is more preferably silica.
It is preferable that content of the said sintering prevention component is 0.5 mass%-20 mass% with respect to a gallium containing zinc oxide particle.
About the said baking process, it carries out in reducing atmosphere, such as nitrogen gas and argon gas, and the temperature can mention the range of 600 to 1,400 degreeC.
The content of gallium in the gallium-containing zinc oxide particles is not particularly limited and may be appropriately selected depending on the intended purpose, but is in the range of 0.01% by mass to 5% by mass with respect to zinc. Is preferred. When the gallium content is low, the excellent electrical characteristics of the zinc oxide particles due to the gallium content may not be exhibited. On the other hand, when the gallium content is high, an electrical failure may occur due to gallium acting as an impurity.
The content of the gallium can be known by a conventionally known method, and is not particularly limited as long as it is a known elemental quantitative analysis means, and the analysis means described above can be appropriately selected according to the purpose. , X-ray photoelectron spectroscopy (XPS), Auger spectroscopic analysis (AES), energy dispersive X-ray spectroscopy (EDX), etc.

The average particle diameter of the gallium-containing zinc oxide particles is preferably 20 nm to 200 nm, and more preferably 50 nm to 150 nm. When the average particle size is less than 20 nm, it may be difficult to form an undercoat layer in a good dispersion state, and when it exceeds 200 nm, excellent electrical characteristics of the undercoat layer may be maintained. It can be difficult.
The average particle diameter of the gallium-containing zinc oxide particles was determined by observing 100 particles observed in the undercoat layer with a transmission electron microscope (TEM), obtaining the projected area, and obtaining a circle having the obtained area. The equivalent diameter can be calculated to determine the particle diameter, and the average value can be determined as the average particle diameter.

The volume resistivity (powder resistivity) of the gallium-containing zinc oxide particles is not particularly limited and may be appropriately selected depending on the intended purpose, but is preferably 10 ² Ω · cm to 10 ¹¹ Ω · cm.
If the volume resistivity is less than 10 ² Ω · cm, a sufficient leak-proof function of the undercoat layer cannot be obtained, and an abnormal image such as a background stain may be caused. On the other hand, when the volume resistivity exceeds 10 ¹¹ Ω · cm, charge transport from the photosensitive layer to the conductive support is not sufficiently performed, which may cause an increase in residual potential.

  The content of the gallium-containing zinc oxide particles in the undercoat layer is not particularly limited and may be appropriately selected depending on the intended purpose, but is preferably 10% by mass to 80% by mass, and 30% by mass to 60% by mass. More preferred. When the content is less than 10% by mass, the volume resistance of the undercoat layer becomes too high, and thus good electrical characteristics may not be maintained. On the other hand, if the content exceeds 80% by mass, leak points due to fine cracks or the like are likely to occur after film formation, and good electrical characteristics may not be maintained.

The gallium-containing zinc oxide particles are preferably subjected to a surface treatment with a surface treatment agent.
-Surface treatment agent-
There is no restriction | limiting in particular as said surface treating agent, According to the objective, it can select suitably, For example, a silane coupling agent, a titanate coupling agent, an aluminum coupling agent, surfactant, etc. are mentioned. These may be used alone or in combination of two or more. Among these, a silane coupling agent is preferable from the viewpoint of giving good electrophotographic characteristics, and a silane coupling agent having an amino group is more preferable from the viewpoint of giving good blocking property to the undercoat layer.

  The silane coupling agent having an amino group is not particularly limited and may be appropriately selected depending on the intended purpose. For example, γ-aminopropyltriethoxysilane, N-β- (aminoethyl) -γ-amino Examples thereof include propyltrimethoxysilane, N-β- (aminoethyl) -γ-aminopropylmethylmethoxysilane, N, N-bis (β-hydroxyethyl) -γ-aminopropyltriethoxysilane. These may be used alone or in combination of two or more.

  There is no restriction | limiting in particular as another silane coupling agent, According to the objective, it can select suitably, For example, vinyl trimethoxysilane, (gamma) -methacryloxypropyl-tris ((beta) -methoxyethoxy) silane, (beta)-( 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-chloro And propyltrimethoxysilane. These may be used alone or in combination of two or more. Moreover, you may use together the said other silane coupling agent with the silane coupling agent which has the said amino group.

  There is no restriction | limiting in particular as a method of processing the said gallium containing zinc oxide particle with the said surface treating agent, According to the objective, it can select suitably, For example, a dry method, a wet method, etc. are mentioned.

-Dry method-
As the dry method, for example, while stirring the gallium-containing zinc oxide particles with a mixer having a large shearing force, the surface treatment agent is directly dropped, or the surface treatment agent dissolved in an organic solvent is dropped. The method of uniformly processing by spraying with dry air and nitrogen gas is mentioned. The surface treatment agent is preferably dropped and sprayed at a temperature not higher than the boiling point of the organic solvent. When spraying at a temperature higher than the boiling point of the organic solvent, the organic solvent evaporates before being uniformly stirred, and the surface treatment agent is locally solidified, which may make it difficult to perform uniform treatment. After the surface treatment agent is dropped and sprayed, baking can be performed at 100 ° C. or higher. The baking is not particularly limited as long as it is a temperature and time at which desired electrophotographic characteristics can be obtained, and can be appropriately selected according to the purpose.

-Wet method-
As the wet method, for example, the gallium-containing zinc oxide particles are dispersed in a solvent using stirring, ultrasonic waves, a sand mill, an attritor, a ball mill, etc., and after adding the surface treatment agent, stirring or dispersing. It is processed uniformly by removing the solvent. Examples of the method for removing the solvent include filtration or distillation. After removing the solvent, baking can be performed at 100 ° C. or higher. The baking is not particularly limited as long as it is a temperature and a time at which desired electrophotographic characteristics can be obtained, and can be appropriately selected according to the purpose. In the wet method, moisture contained in the gallium-containing zinc oxide particles can be removed before the surface treatment agent is added. Examples of the method for removing the water content include a method for removing the water while stirring and heating in a solvent used for the surface treatment, and a method for removing the water by azeotroping with the solvent.

<< Binder resin >>
There is no restriction | limiting in particular as said binder resin, According to the objective, it can select suitably, For example, a thermoplastic resin, a thermosetting resin, etc. are mentioned. These may be used alone or in combination of two or more. Among these, the binder resin is preferably a binder resin having high solvent resistance with respect to a general organic solvent in consideration of applying a photosensitive layer described later on the undercoat layer. Examples of the high solvent-resistant binder resin include water-soluble resins such as polyvinyl alcohol, casein, and sodium polyacrylate; alcohol-soluble resins such as copolymer nylon and methoxymethylated nylon; polyurethane, melamine resin, and phenol resin And curable resins that form a three-dimensional network structure such as alkyd-melamine resins and epoxy resins.

<< Other ingredients >>
The undercoat layer may contain other components for improving electrical characteristics, improving environmental stability, and improving image quality.
The other components are not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include electron transport materials; electron transport pigments such as polycyclic condensation systems and azo systems; silane coupling agents; zirconium Examples include chelate compounds; titanium chelate compounds; aluminum chelate compounds; fluorenone compounds; titanium alkoxide compounds; organic titanium compounds, and antioxidants, plasticizers, lubricants, ultraviolet absorbers, and leveling agents described later. These may be used alone or in combination of two or more.

−Electron transporting material−
Examples of the electron transporting substance include quinone compounds such as chloranil and bromoanil; tetracyanoquinodimethane compounds; 2,4,7-trinitrofluorenone, 2,4,5,7-tetranitro-9-fluorenone Fluorenone compounds such as 2- (4-biphenyl) -5- (4-tert-butylphenyl) -1,3,4-oxadiazole, 2,5-bis (4-naphthyl) -1,3,4 -Oxadiazole compounds such as oxadiazole and 2,5-bis (4-diethylaminophenyl) -1,3,4 oxadiazole; xanthone compounds; thiophene compounds; 3,3 ', 5,5' tetra And diphenoquinone compounds such as -t-butyldiphenoquinone. These may be used alone or in combination of two or more.

-Silane coupling agent-
The silane coupling agent is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof 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. These may be used alone or in combination of two or more.

The silane coupling agent can be used by being added to the coating solution for the undercoat layer separately from that used for the surface treatment of the gallium-containing zinc oxide particles.
-Zirconium chelate compound-
The zirconium chelate compound is not particularly limited and may be appropriately selected depending on the intended purpose. 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, etc. It is done. These may be used alone or in combination of two or more.

-Titanium chelate compound-
The titanium chelate compound is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof 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. These may be used alone or in combination of two or more.

-Aluminum chelate compound-
The aluminum chelate compound is not particularly limited and may be appropriately selected depending on the intended purpose. For example, aluminum isopropylate, monobutoxy aluminum diisopropylate, aluminum butyrate, diethyl acetoacetate aluminum diisopropylate, aluminum tris (Ethyl acetoacetate) and the like. These may be used alone or in combination of two or more.

<< Formation method of undercoat layer >>
There is no restriction | limiting in particular as a formation method of the said undercoat layer, It can form using a suitable solvent and a coating method. The timing of adding the binder resin to the undercoat layer coating liquid used in the coating method may be before or after the dispersion of the gallium-containing zinc oxide particles.

  The solvent is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include alcohol solvents such as methanol, ethanol, propanol and butanol; ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone. Ester solvents such as ethyl acetate and butyl acetate; ether solvents such as tetrahydrofuran, dioxane and propyl ether; halogen solvents such as dichloromethane, dichloroethane, trichloroethane and chlorobenzene; aromatic solvents such as benzene, toluene and xylene; methyl Examples include cellosolve solvents such as cellosolve, ethyl cellosolve, cellosolve acetate, and the like. These may be used alone or in combination of two or more.

The method for dispersing the gallium-containing zinc oxide particles in the undercoat layer coating liquid is not particularly limited and may be appropriately selected depending on the intended purpose. For example, a ball mill, a sand mill, a vibration mill, a three-roll mill, an atom Examples thereof include a lighter, a pressure homogenizer, and a dispersion method using ultrasonic dispersion.
The coating method is not particularly limited and can be appropriately selected depending on the viscosity of the coating solution, the desired thickness of the undercoat layer, and the like. For example, dip coating method, spray coating method, bead coating method, ring coating Law.
After coating using the undercoat layer coating solution, it may be dried by heating in an oven or the like, if necessary. The drying temperature of the undercoat layer is not particularly limited and may be appropriately selected according to the type of solvent contained in the undercoat layer coating solution. -150 degreeC is more preferable.

<< Average thickness of undercoat layer >>
There is no restriction | limiting in particular as average thickness of the said undercoat layer, Although it can select suitably by the electrical property and lifetime of the electrophotographic photoreceptor to manufacture, 5 micrometers-50 micrometers are preferable, and 10 micrometers-30 micrometers are more preferable.
When the thickness is less than 5 μm, a charge opposite in polarity to the surface of the electrophotographic photosensitive member flows into the photosensitive layer from the conductive support, thereby causing a background-like image defect due to poor charging property. May occur. On the other hand, when the thickness exceeds 50 μm, defects such as a decrease in light attenuation function such as an increase in residual potential and a decrease in repeated stability may easily occur.

<Photosensitive layer>
The photosensitive layer may be a laminated type photosensitive layer or a single layer type photosensitive layer.
<< Single-layer type photosensitive layer >>
The single-layer type photosensitive layer is a layer having a charge generation function and a charge transport function at the same time.
The single-layer type photosensitive layer contains a charge generating substance, a charge transporting substance, and a binder resin, and further contains other components as necessary.

-Charge generation material-
The charge generating material is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include the same materials as those used in the laminated photosensitive layer described later. There is no restriction | limiting in particular as content of the said charge generation substance, Although it can select suitably according to the objective, 5 mass parts-40 mass parts are preferable with respect to 100 mass parts of said binder resins.

-Charge transport material-
There is no restriction | limiting in particular as said charge transport substance, According to the objective, it can select suitably, For example, the substance similar to what is used by the laminated type photosensitive layer mentioned later etc. are mentioned. There is no restriction | limiting in particular as content of the said charge transport material, Although it can select suitably according to the objective, 190 mass parts or less are preferable with respect to 100 mass parts of said binder resin, and 50 mass parts-150 mass parts. Part by mass is more preferable.

-Binder resin-
There is no restriction | limiting in particular as said binder resin, According to the objective, it can select suitably, For example, the binder resin similar to what is used by the laminated type photosensitive layer mentioned later etc. are mentioned.

-Other ingredients-
The other components are not particularly limited and may be appropriately selected depending on the purpose. For example, the same low molecular charge transport material as used in the laminated photosensitive layer described later, the same solvent, and the later described Antioxidants, plasticizers, lubricants, ultraviolet absorbers, leveling agents and the like.

-Method for forming a single-layer type photosensitive layer-
The method for forming the single-layer photosensitive layer is not particularly limited and may be appropriately selected depending on the intended purpose. For example, a charge generating material, a charge transporting material, a binder resin, other components, etc. Examples thereof include a method of forming a coating liquid obtained by dissolving or dispersing in a suitable solvent (for example, tetrahydrofuran, dioxane, dichloroethane, cyclohexane, etc.) by coating or drying.
There is no restriction | limiting in particular as a method to apply the said coating liquid, According to the objective, it can select suitably, For example, a dip coating method, a spray coat, a bead coat, a ring coat etc. are mentioned. Moreover, you may add a plasticizer, a leveling agent, antioxidant, etc. as needed.
There is no restriction | limiting in particular as thickness of the said single layer type photosensitive layer, Although it can select suitably according to the objective, 5 micrometers-25 micrometers are preferable.

<< Laminated Photosensitive Layer >>
Since the layered photosensitive layer has independent charge generation functions and charge transport functions, it has at least a charge generation layer and a charge transport layer in this order. In addition, a conventionally well-known thing can be used for the said charge generation layer and the said charge transport layer.
In the stacked photosensitive layer, the stacking order of the charge generation layer and the charge transport layer is not particularly limited and can be appropriately selected according to the purpose. Many charge generation materials are chemically stable. However, exposure to an acidic gas such as a discharge product around a charger in an electrophotographic imaging process causes a reduction in charge generation efficiency. For this reason, it is preferable to laminate the charge transport layer on the charge generation layer.

-Charge generation layer-
The charge generation layer contains a charge generation material, preferably contains a binder resin, and further contains other components such as an antioxidant described later as required.

-Charge generation material-
There is no restriction | limiting in particular as said charge generation substance, According to the objective, it can select suitably, For example, an inorganic material, an organic material, etc. are mentioned.

---- Inorganic material ---
The inorganic material is not particularly limited and may be appropriately selected depending on the intended purpose. For example, crystalline selenium, amorphous-selenium, selenium-tellurium, selenium-tellurium-halogen, selenium-arsenic compound, amorphous silicon (For example, dangling bonds terminated with hydrogen atoms, halogen atoms, etc .; those containing boron atoms, phosphorous atoms, etc. are preferred).

---- Organic materials ---
The organic material is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include phthalocyanine pigments such as metal phthalocyanine and metal-free phthalocyanine; azulenium salt pigments, squaric acid methine pigments, and carbazole skeletons. Azo pigments having a triphenylamine skeleton, azo pigments having a diphenylamine skeleton, azo pigments having a dibenzothiophene skeleton, azo pigments having a fluorenone skeleton, azo pigments having an oxadiazole skeleton, azo having a bisstilbene skeleton Pigment, azo pigment having distyryl oxadiazole skeleton, azo pigment having distyryl carbazole skeleton, perylene pigment, anthraquinone or polycyclic quinone pigment, quinoneimine pigment, diphenylmethane and triphenylmethane face , Benzoquinone and naphthoquinone pigments, cyanine and azomethine pigments, indigoid pigments, and bis-benzimidazole-based pigments. These may be used individually by 1 type and may use 2 or more types together.

--Binder resin--
The binder resin is not particularly limited and can be appropriately selected according to the purpose. For example, polyamide resin, polyurethane resin, epoxy resin, polyketone resin, polycarbonate resin, silicone resin, acrylic resin, polyvinyl butyral resin, Examples thereof include polyvinyl formal resin, polyvinyl ketone resin, polystyrene resin, poly-N-vinyl carbazole resin, polyacrylamide resin and the like. These may be used individually by 1 type and may use 2 or more types together.
As the binder resin, in addition to the above-mentioned binder resin, a charge transporting polymer material having a charge transport function may be included. Polymer materials such as polycarbonate, polyester, polyurethane, polyether, polysiloxane, and acrylic resin having a pyrazoline skeleton, polymer materials having a polysilane skeleton, and the like can be used.

-Other ingredients-
The other components are not particularly limited and may be appropriately selected depending on the purpose. For example, low molecular charge transport materials, solvents, antioxidants, plasticizers, lubricants, ultraviolet absorbers described below, and Examples include leveling agents.
There is no restriction | limiting in particular as content of the said other component, Although it can select suitably according to the objective, 0.01 mass%-10 mass% are preferable with respect to the total mass of the layer to add.

--- Low molecular charge transport material ---
There is no restriction | limiting in particular as said low molecular charge transport material, According to the objective, it can select suitably, For example, an electron transport material, a hole transport material, etc. are mentioned.
The electron transport material is not particularly limited and may be appropriately selected depending on the intended purpose. For example, chloroanil, bromilyl, tetracyanoethylene, tetracyanoquinodimethane, 2,4,7-trinitro-9-fluorenone 2,4,5,7-tetranitro-9-fluorenone, 2,4,5,7-tetranitroxanthone, 2,4,8-trinitrothioxanthone, 2,6,8-trinitro-4H-indeno [1 , 2-b] thiophen-4-one, 1,3,7-trinitrodibenzothiophene-5,5-dioxide, diphenoquinone derivatives and the like. These may be used individually by 1 type and may use 2 or more types together.

  The hole transport material is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include oxazole derivatives, oxadiazole derivatives, imidazole derivatives, monoarylamine derivatives, diarylamine derivatives, and triarylamine derivatives. , Stilbene derivatives, α-phenylstilbene derivatives, benzidine derivatives, diarylmethane derivatives, triarylmethane derivatives, 9-styrylanthracene derivatives, pyrazoline derivatives, divinylbenzene derivatives, hydrazone derivatives, indene derivatives, butadiene derivatives, pyrene derivatives, etc. Derivatives, enamine derivatives and the like. These may be used individually by 1 type and may use 2 or more types together.

--- Solvent ---
The solvent is not particularly limited and may be appropriately selected depending on the intended purpose.For example, tetrahydrofuran, dioxane, dioxolane, toluene, dichloromethane, monochlorobenzene, dichloroethane, cyclohexanone, cyclopentanone, anisole, xylene, methyl ethyl ketone, Acetone, ethyl acetate, butyl acetate and the like can be mentioned. These may be used individually by 1 type and may use 2 or more types together.

--Method of forming charge generation layer--
The method for forming the charge generation layer is not particularly limited and may be appropriately selected depending on the purpose. For example, the charge generation material and the binder resin are dissolved or dispersed in the other components such as the solvent. For example, a method of forming the coating liquid obtained by applying the coating liquid on the conductive support and drying it may be used. In addition, the said coating liquid can be apply | coated by the casting method etc.
There is no restriction | limiting in particular as thickness of the said charge generation layer, Although it can select suitably according to the objective, 0.01 micrometer-5 micrometers are preferable, and 0.05 micrometer-2 micrometers are more preferable.

-Charge transport layer-
The charge transport layer is a layer intended to hold a charged charge and to couple the charge generated and separated in the charge generation layer by exposure to the charged charge held by movement. In order to achieve the purpose of holding the charged charge, it is required that the electric resistance is high. Further, in order to achieve the purpose of obtaining a high surface potential with the charged charge that has been held, it is required that the dielectric constant is small and the charge mobility is good.
The charge transport layer preferably includes a charge transport material, preferably includes a binder resin, and further includes other components as necessary.

-Charge transport material-
The charge transport material is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include an electron transport material, a hole transport material, and a polymer charge transport material.
There is no restriction | limiting in particular as content in the charge transport layer whole quantity of the said charge transport material, Although it can select suitably according to the objective, 20 mass%-80 mass% are preferable, and 30 mass%-70 mass% are preferable. More preferred. If the content is less than 20% by mass, the charge transporting property of the charge transport layer may be reduced, so that desired light attenuation characteristics may not be obtained. The body may wear more than necessary due to various hazards. On the other hand, when the content of the charge transport material in the charge transport layer is within the more preferable range, a desired light attenuation can be obtained, and an electrophotographic photoreceptor with less wear can be obtained by use. This is advantageous.

---- Electron transport material ---
The electron transport material (electron-accepting material) is not particularly limited and may be appropriately selected depending on the intended purpose. For example, chloroanil, bromoanil, tetracyanoethylene, tetracyanoquinodimethane, 2, 4, 7 -Trinitro-9-fluorenone, 2,4,5,7-tetranitro-9-fluorenone, 2,4,5,7-tetranitroxanthone, 2,4,8-trinitrothioxanthone, 2,6,8-trinitro -4H-indeno [1,2-b] thiophene-4-one, 1,3,7-trinitrodibenzothiophene-5,5-dioxide, and the like. These may be used alone or in combination of two or more.

--- Hole transport material ---
The hole transport material (electron donating material) is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include oxazole derivatives, oxadiazole derivatives, imidazole derivatives, triphenylamine derivatives, 9- (P-diethylaminostyrylanthracene), 1,1-bis- (4-dibenzylaminophenyl) propane, styrylanthracene, styrylpyrazoline, phenylhydrazones, α-phenylstilbene derivatives, thiazole derivatives, triazole derivatives, phenazine derivatives, Examples include acridine derivatives, benzofuran derivatives, benzimidazole derivatives, thiophene derivatives, and the like. These may be used alone or in combination of two or more.

--- Polymer charge transport material ---
The polymer charge transport material is a material having both the functions of a binder resin and a charge transport material described later.
The polymer charge transport material is not particularly limited and may be appropriately selected depending on the intended purpose.For example, a polymer having a carbazole ring, a polymer having a hydrazone structure, a polysilylene polymer, or a triarylamine structure may be used. For example, a polymer having a triarylamine structure described in Japanese Patent No. 3852812, Japanese Patent No. 3990499, and the like, a polymer having an electron donating group, and other polymers. These may be used individually by 1 type, may use 2 or more types together, and may use together with the binder resin mentioned later at the point of abrasion durability or film forming property.

  The content of the polymer charge transport material in the total mass of the charge transport layer is not particularly limited and may be appropriately selected depending on the intended purpose. The polymer charge transport material and the binder resin are used in combination. In the case, 40 mass%-90 mass% is preferable, and 50 mass%-80 mass% is more preferable.

--Binder resin--
The binder resin is not particularly limited and can be appropriately selected depending on the purpose. For example, polycarbonate resin, polyester resin, methacrylic resin, acrylic resin, polyethylene resin, polyvinyl chloride resin, polyvinyl acetate resin, Polystyrene resin, phenol resin, epoxy resin, polyurethane resin, polyvinylidene chloride resin, alkyd resin, silicone resin, polyvinyl carbazole resin, polyvinyl butyral resin, polyvinyl formal resin, polyacrylate resin, polyacrylamide resin, phenoxy resin, and the like are used. These may be used alone or in combination of two or more.
The charge transport layer can also include a copolymer of a crosslinkable binder resin and a crosslinkable charge transport material.

-Other ingredients-
There is no restriction | limiting in particular as said other component, According to the objective, it can select suitably, For example, a solvent, the below-mentioned antioxidant, a plasticizer, a lubricant, a ultraviolet absorber, a leveling agent etc. are mentioned. .
There is no restriction | limiting in particular as content of the said other component, Although it can select suitably according to the objective, 0.01 mass%-10 mass% are preferable with respect to the total mass of the layer to add.

--- Solvent ---
The solvent is not particularly limited and may be appropriately selected depending on the purpose. The same solvent as the charge generation layer can be used, but a solvent that dissolves the charge transport material and the binder resin satisfactorily. preferable. These may be used singly or in combination of two or more.

---- Plasticizer ---
The plasticizer is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include plasticizers for general resins such as dibutyl phthalate and dioctyl phthalate.

--Method of forming charge transport layer--
The method for forming the charge transport layer is not particularly limited and may be appropriately selected depending on the intended purpose. For example, the charge transport material and the binder resin are dissolved or dispersed in the other components such as the solvent. And a method of forming the coating liquid obtained by applying the coating liquid on the charge generation layer and heating or drying.
The method for applying the coating liquid used for forming the charge transport layer is not particularly limited, and may be appropriately selected according to the purpose such as the viscosity of the coating liquid and the desired thickness of the charge transport layer. Examples thereof include a dip coating method, a spray coating method, a bead coating method, and a ring coating method.
From the viewpoint of electrophotographic characteristics and film viscosity, the charge transport layer needs to be heated by some means to remove the solvent from the charge transport layer.
Examples of the heating method include a method of heating heat energy such as air, nitrogen and other gases, steam, various heat media, infrared rays, and electromagnetic waves from the coated surface side or the support side.
There is no restriction | limiting in particular as temperature at the time of the said heating, Although it can select suitably according to the objective, 100 to 170 degreeC is preferable. When the temperature is less than 100 ° C., the organic solvent in the film cannot be sufficiently removed, and electrophotographic characteristics and wear durability may be deteriorated. On the other hand, when the temperature exceeds 170 ° C., not only the surface of the surface is distorted and cracks are generated, peeling occurs at the interface with the adjacent layer, etc., but volatile components in the photosensitive layer are scattered to the outside. In this case, desired electrical characteristics may not be obtained.

  There is no restriction | limiting in particular as thickness of the said charge transport layer, Although it can select suitably according to the objective, From the point of resolution thru | or response, 50 micrometers or less are preferable and 45 micrometers or less are more preferable. The lower limit varies depending on the system to be used (particularly charging potential), but is preferably 5 μm or more.

<Other layers>
There is no restriction | limiting in particular as said other layer, According to the objective, it can select suitably, For example, a protective layer, an intermediate | middle layer, a 2nd undercoat layer etc. are mentioned.

<< Protective layer >>
The protective layer (hereinafter sometimes referred to as a surface layer) can be provided on the photosensitive layer for the purpose of improving the durability of the electrophotographic photosensitive member and improving other functions. The protective layer contains at least a binder resin and a filler, and further contains other components as necessary.

-Binder resin-
The binder resin is not particularly limited and may be appropriately selected depending on the intended purpose. For example, AS resin, ABS resin, ACS resin, olefin-vinyl monomer copolymer, chlorinated polyether resin, allyl resin , Phenol resin, polyacetal resin, polyamide resin, polyamideimide resin, polyacrylate resin, polyallylsulfone resin, polybutylene resin, polybutylene terephthalate resin, polycarbonate resin, polyethersulfone resin, polyether resin, polyethylene terephthalate resin, polyimide resin, acrylic resin Examples include resins, polymethylpentene resins, polypropylene resins, polyphenylene oxide resins, polysulfone resins, polyurethane resins, polyvinyl chloride resins, polyvinylidene chloride resins, and epoxy resins. These may be used singly or in combination of two or more. Among these, polycarbonate resin and polyacrylate resin are preferable from the viewpoint of dispersibility of the filler, residual potential, and coating film defects.

-Filler-
The filler is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include metal oxide fine particles.
The metal oxide fine particles are not particularly limited and may be appropriately selected depending on the purpose. For example, the metal oxide fine particles include aluminum oxide, zinc oxide, titanium oxide, tin oxide, antimony oxide, indium oxide, bismuth oxide, and tin. Indium oxide, tin oxide containing antimony or tantalum, zirconium oxide containing antimony, and the like. These may be used singly or in combination of two or more.

The method for forming the protective layer is not particularly limited, and can be formed using an appropriate solvent and coating method as in the above-described photosensitive layer. For example, dip coating method, spray coating method, beat coating method, nozzle Examples thereof include a coating method, a spinner coating method, and a ring coating method.
The solvent used for the method for forming the protective layer is not particularly limited and may be appropriately selected depending on the intended purpose.For example, tetrahydrofuran, dioxane, toluene, dichloromethane, monochlorobenzene, dichloroethane, cyclohexanone, methyl ethyl ketone, acetone and the like. Can be mentioned.
The solvent is preferably a solvent having a high viscosity when the binder resin or filler is dispersed and a high volatility at the time of coating. If there is no solvent that satisfies these conditions, it is possible to use a mixture of two or more solvents having the respective physical properties, which may have a great effect on the dispersibility and residual potential of the filler. is there.
The addition of the charge transport materials mentioned for the charge transport layer to the protective layer is effective and useful for reducing the residual potential and improving the image quality.
There is no restriction | limiting in particular as thickness of the said protective layer, Although it can select suitably according to the objective, 1 micrometers-5 micrometers are preferable at the point of abrasion resistance.

-Intermediate layer-
The intermediate layer can be provided between the charge transport layer and the surface layer for the purpose of suppressing mixing of charge transport layer components into the surface layer or improving adhesion between the two layers.
The intermediate layer contains a binder resin and, if necessary, further contains other components such as an antioxidant described later. The intermediate layer is preferably insoluble or hardly soluble in the surface layer coating solution.
There is no restriction | limiting in particular as binder resin contained in the said intermediate | middle layer, According to the objective, it can select suitably, For example, polyamide, alcohol soluble nylon, polyvinyl butyral, polyvinyl alcohol, etc. are mentioned.
There is no restriction | limiting in particular as a formation method of the said intermediate | middle layer, According to the objective, it can select suitably, For example, the method etc. which form using the suitable solvent and coating method similar to the said photosensitive layer are mentioned.
There is no restriction | limiting in particular as thickness of the said intermediate | middle layer, Although it can select suitably according to the objective, 0.05 micrometer-2 micrometers are preferable.

<< Second subbing layer >>
In the electrophotographic photosensitive member, the second undercoat layer can be provided between the photosensitive layer and the protective layer. The second undercoat layer contains a binder resin, and further contains other components as necessary.
There is no restriction | limiting in particular as said binder resin, According to the objective, it can select suitably, For example, polyamide, alcohol-soluble nylon, water-soluble polyvinyl butyral, polyvinyl butyral, polyvinyl alcohol etc. are mentioned.
There is no restriction | limiting in particular as a formation method of a said 2nd undercoat layer, It can form using a suitable solvent and a coating method.
There is no restriction | limiting in particular as thickness of the said 2nd undercoat layer, Although it can select suitably according to the objective, 0.05 micrometer-2 micrometers are preferable.

  In the electrophotographic photosensitive member of the present invention, the charge generation layer, the charge transport layer, the subbing layer, the protection, in order to improve environmental resistance, in particular, for the purpose of preventing a decrease in sensitivity and an increase in residual potential. As other components, an antioxidant, a plasticizer, a lubricant, an ultraviolet absorber, a leveling agent, and the like can be added to each layer such as the layer and the second undercoat layer.

  There is no restriction | limiting in particular as said antioxidant, According to the objective, it can select suitably, For example, a phenol type compound, paraphenylenediamine, hydroquinones, an organic sulfur compound, an organic phosphorus compound etc. are mentioned. . These may be used singly or in combination of two or more.

  The plasticizer is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include a phosphate ester plasticizer, a phthalate ester plasticizer, an aromatic carboxylic ester plasticizer, and an aliphatic diester. Basic acid ester plasticizer, fatty acid ester plasticizer, oxyacid ester plasticizer, epoxy plasticizer, dihydric alcohol ester plasticizer, chlorine-containing plasticizer, polyester plasticizer, sulfonic acid derivative, citric acid derivative, Other plasticizers can be mentioned. These may be used singly or in combination of two or more.

  The lubricant is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include hydrocarbon compounds, fatty acid compounds, fatty acid amide compounds, ester compounds, alcohol compounds, metal soaps, natural waxes. And other lubricants. These may be used singly or in combination of two or more.

  The ultraviolet absorber is not particularly limited and may be appropriately selected depending on the intended purpose. For example, a benzophenone ultraviolet absorber, a salicylate ultraviolet absorber, a benzotriazole ultraviolet absorber, a cyanoacrylate ultraviolet absorber , Quencher (metal complex salt ultraviolet absorber), HALS (hindered amine light stabilizer) and the like. These may be used singly or in combination of two or more.

  The leveling agent is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include silicone oils such as dimethyl silicone oil and methyl phenyl silicone oil; polymers or oligomers having a perfluoroalkyl group in the side chain. Etc. These may be used individually by 1 type and may use 2 or more types together.

<Support>
The support is not particularly limited as long as it has a volume resistivity of 1 × 10 ¹⁰ Ω · cm or less, and can be appropriately selected according to the purpose. An endless belt (such as an endless nickel belt or an endless stainless steel belt) disclosed in Japanese Patent Laid-Open No. 52-36016 may be used.
There is no restriction | limiting in particular as a formation method of the said support body, According to the objective, it can select suitably, For example, a metal (aluminum, nickel, chromium, nichrome, copper, gold | metal | money, silver, platinum etc.) or a metal oxide A method of forming a film by coating or sputtering (tin oxide, indium oxide, etc.) and coating a support (film, cylindrical plastic, paper, etc.); metal (aluminum, aluminum alloy, nickel, stainless steel, etc.) For example, by extruding, drawing, etc., and subjecting to surface treatment (cutting, superfinishing, polishing, etc.).
The support may be provided with a conductive layer on the support.
The method for forming the conductive layer is not particularly limited and may be appropriately selected depending on the purpose. For example, the conductive layer and the binder resin may be dispersed or dissolved in a solvent as necessary. A method of forming the applied coating liquid on the conductive support, such as polyvinyl chloride, polypropylene, polyester, polystyrene, polyvinylidene chloride, polyethylene, chlorinated rubber, and Teflon (registered trademark) Examples include a method of forming using a heat-shrinkable tube containing conductive powder.
There is no restriction | limiting in particular as said electroconductive powder, According to the objective, it can select suitably, For example, carbon fine particles, such as carbon black and acetylene black; Aluminum, nickel, iron, nichrome, copper, zinc, silver, etc. And metal oxide powders such as conductive tin oxide and ITO.

There is no restriction | limiting in particular as binder resin used for the said electroconductive layer, According to the objective, it can select suitably, For example, a thermoplastic resin, a thermosetting resin, a photocurable resin etc. are mentioned, Specifically, Polystyrene resin, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer, polyester resin, polyvinyl chloride resin, vinyl chloride-vinyl acetate copolymer, polyvinyl acetate resin, Polyvinylidene chloride resin, polyarylate resin, phenoxy resin, polycarbonate resin, cellulose acetate resin, ethyl cellulose resin, polyvinyl butyral resin, polyvinyl formal resin, polyvinyl toluene resin, poly-N-vinylcarbazole, acrylic resin, silicone resin, epoxy resin, Melamine resin, Ureta Resins, phenol resins, and alkyd resins.
There is no restriction | limiting in particular as a solvent used for the said electroconductive layer, According to the objective, it can select suitably, For example, tetrahydrofuran, a dichloromethane, methyl ethyl ketone, toluene etc. are mentioned.

[Embodiment of electrophotographic photosensitive member]
Hereinafter, embodiments of the electrophotographic photosensitive member of the present invention will be described.
<First Embodiment>
The layer structure of the electrophotographic photoreceptor according to the first embodiment will be described with reference to FIG.
FIG. 1 is a view showing a layer structure of an electrophotographic photosensitive member having a single layer type photosensitive layer, in which an undercoat layer 32 and a single layer type photosensitive layer 33 are sequentially laminated on a conductive support 31. is there.
<Second Embodiment>
The layer structure of the electrophotographic photosensitive member according to the second embodiment will be described with reference to FIG.
FIG. 2 shows a configuration having a laminated photosensitive layer, and shows a layer configuration of an electrophotographic photosensitive member in which an undercoat layer 32, a charge generation layer 35, and a charge transport layer 37 are sequentially laminated on a conductive support 31. It is a figure. The charge generation layer 35 and the charge transport layer 37 correspond to the photosensitive layer.
<Third Embodiment>
The layer structure of the electrophotographic photosensitive member according to the third embodiment will be described with reference to FIG.
FIG. 3 is a configuration having a single-layer type photosensitive layer, and shows a layer configuration of an electrophotographic photosensitive member in which an undercoat layer 32, a photosensitive layer 33, and a protective layer 39 are sequentially laminated on a conductive support 31. FIG.
<Fourth Embodiment>
The layer configuration of the electrophotographic photosensitive member according to the fourth embodiment will be described with reference to FIG.
FIG. 4 shows a structure having a laminated type photosensitive layer. An electrophotographic photosensitive member in which an undercoat layer 32, a charge generation layer 35, a charge transport layer 37, and a protective layer 39 are sequentially laminated on a conductive support 31. It is the figure which showed the layer structure. The charge generation layer 35 and the charge transport layer 37 correspond to the photosensitive layer.

(Image forming apparatus and image forming method)
The image forming apparatus of the present invention includes an electrophotographic photosensitive member, a charging unit that charges the surface of the electrophotographic photosensitive member, an exposure unit that exposes the charged surface of the electrophotographic photosensitive member to form an electrostatic latent image, It comprises at least developing means for developing the electrostatic latent image with toner to form a visible image, and transfer means for transferring the visible image to a recording medium, and if necessary, other means It has. The electrophotographic photosensitive member used in the image forming apparatus is the above-described electrophotographic photosensitive member of the present invention. The charging unit and the exposure unit may be collectively referred to as an electrostatic latent image forming unit.

The image forming method of the present invention comprises a charging step of charging the surface of an electrophotographic photosensitive member with a charging unit, and exposing the charged electrophotographic photosensitive member with an image exposing unit to form an electrostatic latent image on the surface of the electrophotographic photosensitive member. An exposure step for forming a toner image, a developing step for forming a toner image on the surface of the electrophotographic photosensitive member on which the electrostatic latent image is formed by a developing unit, and a transfer unit for transferring the formed toner image to a recording medium. It includes at least a transfer step, and further includes other steps as necessary.
The charging process and the exposure process may be collectively referred to as an electrostatic latent image forming process.
The image forming method is a method performed by each unit of the image forming apparatus.

<Charging means and charging step>
The charging means is not particularly limited and may be appropriately selected according to the purpose. For example, a known contact charger including a conductive or semiconductive roll, brush, film, rubber blade, etc. And non-contact chargers using corona discharge such as corotron and scorotron (including proximity-type non-contact chargers having a gap of 100 μm or less between the surface of the electrophotographic photosensitive member and the charger).
The charging unit includes a charging member provided in contact with or close to the surface of the electrophotographic photosensitive member, and applies a voltage in which an alternating current component is superimposed on a direct current component to the charging member. The charging means is preferably a charging means for forming a corona discharge on the surface of the photosensitive member to charge the surface of the electrophotographic photosensitive member.
The charging step can be performed by the charging means and is a step of charging the surface of the electrophotographic photosensitive member.

<Exposure means and exposure process>
The exposure means is not particularly limited as long as the surface of the electrophotographic photosensitive member charged by the charging means can be exposed like an image to be formed, and can be appropriately selected according to the purpose. Examples include various exposure devices such as a copying optical system, a rod lens array system, a laser optical system, a liquid crystal shutter optical system, and an LED optical system, and examples of the light source in the exposure device include a light emitting diode (LED) and a semiconductor laser. (LD), electroluminescence (EL), etc. and the light source etc. which can ensure high brightness | luminance are mentioned. In the present invention, an optical backside system that performs imagewise exposure from the backside of the electrophotographic photosensitive member may be employed.
The exposure step can be performed by the exposure means, and is a step of exposing the charged electrophotographic photosensitive member surface to form an electrostatic latent image.

<Developing means and development process>
The developing means is not particularly limited and may be appropriately selected depending on the purpose. For example, as long as development can be performed using the toner or developer, there is no particular limitation, and the developing means is appropriately selected according to the purpose. However, it is preferable to have at least a developing unit that accommodates the developer and can apply the developer to the electrostatic latent image in a contact or non-contact manner. The developing unit may be a dry developing type, a wet developing type, a single color developing unit, or a multicolor developing unit. For example, a developer having a stirrer for charging the developer by frictional stirring and a rotatable magnet roller is preferable. In the developing unit, for example, the toner and the carrier are mixed and stirred, and the toner is charged by friction at that time, and held on the surface of the rotating magnet roller in a raised state to form a magnetic brush. Since the magnet roller is disposed in the vicinity of the electrophotographic photosensitive member, a part of the toner constituting the magnetic brush formed on the surface of the magnet roller is electrically attracted to the electrophotographic photosensitive member. Move to the surface of the body. As a result, the electrostatic latent image is developed with the toner, and a visible image is formed with the toner on the surface of the electrophotographic photosensitive member.
The developing step can be carried out by the developing means, and is a step of developing the electrostatic latent image with toner to form a visible image.

<Transfer means and transfer process>
The transfer means is a means for transferring the visible image to a recording medium, and uses a method for directly transferring a visible image from the surface of the electrophotographic photosensitive member to a recording medium, and an intermediate transfer member. There is a method in which a visible image is primarily transferred onto the recording medium, and then the visible image is secondarily transferred onto the recording medium. Either aspect can be used satisfactorily, but the former (direct transfer) method with a small number of transfers is preferred when the adverse effect of the transfer is great when the image quality is improved. The transfer can be performed, for example, by charging the electrophotographic photosensitive member with the transfer charger using the visible image, and can be performed by the transfer unit.
The transfer step can be performed by the transfer unit, and is a step of transferring the visible image to a recording medium.

<Other means and other processes>
The other steps and other means are not particularly limited and may be appropriately selected depending on the purpose. For example, the fixing step and the fixing unit, the neutralization step and the neutralization unit, the cleaning step and the cleaning unit, the recycling step, and the like. A recycling means, a control process, a control means, etc. are mentioned.

-Fixing means and fixing process-
The fixing unit is not particularly limited and may be appropriately selected depending on the purpose. However, a known heating and pressing unit is preferable, and the heating and pressing unit includes a combination of a heating roller and a pressing roller, A combination of a heating roller, a pressure roller, and an endless belt is exemplified, and the heating in the heating and pressing means is usually preferably 80 ° C to 200 ° C. The fixing may be performed, for example, every time the toner of each color is transferred to the recording medium, or may be performed simultaneously in a state where the toner of each color is stacked.
The fixing step can be performed by the fixing unit, and is a step of fixing the transferred image transferred to the recording medium.

-Static elimination means and static elimination process-
The neutralizing means is not particularly limited and may be appropriately selected from known neutralizers as long as it can apply a neutralizing bias to the electrophotographic photosensitive member. For example, a neutralizing lamp is preferably used. Can be mentioned.
The static elimination step can be performed by the static elimination means, and is a step of performing static elimination by applying a static elimination bias to the electrophotographic photosensitive member.

-Cleaning means and cleaning process-
The cleaning means is not particularly limited as long as it can remove the electrophotographic toner remaining on the electrophotographic photosensitive member, and can be appropriately selected from known cleaners. For example, a magnetic brush cleaner Suitable examples include electrostatic brush cleaners, magnetic roller cleaners, blade cleaners, brush cleaners, web cleaners, and the like.
The cleaning step can be performed by the cleaning unit, and is a step of removing the toner remaining on the electrophotographic photosensitive member.

-Recycling means and recycling process-
There is no restriction | limiting in particular as said recycling means, A well-known conveyance means etc. are mentioned.
The recycling step can be performed by the recycling unit, and is a step of recycling the toner removed by the cleaning step to the developing unit.

-Control means and control process-
The control means is not particularly limited as long as the movement of each means can be controlled, and can be appropriately selected according to the purpose. Examples thereof include devices such as a sequencer and a computer.
The said control process is a process which can be implemented by the said control means and controls each said process.

[Embodiment of Image Forming Apparatus]
Hereinafter, embodiments of the image forming apparatus of the present invention will be described.
FIG. 5 is a schematic diagram for explaining the image forming apparatus of the present invention. A charging unit 3, an exposure unit 5, a developing unit 6, a transfer unit 10, and the like are arranged around the electrophotographic photosensitive member 1.
First, the electrophotographic photoreceptor 1 is charged on average by the charging means 3 shown in FIG. As the charging means 3, a corotron device, a scorotron device, a solid discharge element, a needle electrode device, a roller charging device, a conductive brush device, or the like is used, and a known method can be used.

  Next, an electrostatic latent image is formed on the uniformly charged electrophotographic photosensitive member 1 by the exposure means 5 shown in FIG. As the light source, all luminescent materials such as a fluorescent lamp, a tungsten lamp, a halogen lamp, a mercury lamp, a sodium lamp, a light emitting diode (LED), a semiconductor laser (LD), and an electroluminescence (EL) can be used. Various types of filters such as a sharp cut filter, a band pass filter, a near infrared cut filter, a dichroic filter, an interference filter, and a color temperature conversion filter can be used to irradiate only light in a desired wavelength range.

  Next, the electrostatic latent image formed on the electrophotographic photoreceptor 1 is visualized by the developing means 6 shown in FIG. Examples of the developing method include a one-component developing method using a dry toner, a two-component developing method, and a wet developing method using a wet toner. When the electrophotographic photoreceptor 1 is positively (negatively) charged and image exposure is performed, a positive (negative) electrostatic latent image is formed on the surface of the photoreceptor. A positive image can be obtained by developing this with negative (positive) toner (electrodetection fine particles), and a negative image can be obtained by developing with positive (negative) toner.

  Next, the toner image visualized on the electrophotographic photoreceptor 1 is transferred onto the recording medium 9 by the transfer means 10 shown in FIG. In addition, a pre-transfer charger 7 may be used for better transfer. As the transfer means 10, an electrostatic transfer method using a transfer charger, a bias roller, or the like; a mechanical transfer method such as an adhesive transfer method or a pressure transfer method; a magnetic transfer method, or the like can be used.

  Further, if necessary, a separation charger 11 and a separation claw 12 may be used as means for separating the recording medium 9 shown in FIG. 5 from the electrophotographic photosensitive member 1. As other separation means, electrostatic adsorption induction separation, side end belt separation, tip grip conveyance, curvature separation, and the like are used. As the separation charger 11, the charging means can be used. In addition, cleaning means such as a fur brush 14 and a cleaning blade 15 are used to clean the toner remaining on the photoconductor after transfer, and the pre-cleaning charger 13 may be used for more efficient cleaning. Good. Other cleaning means include a web method, a magnet brush method, and the like, but each may be used alone or in combination. Further, in order to remove the latent image on the electrophotographic photosensitive member 1, the charge eliminating means 2 may be used. As the charge removal means 2, a charge removal lamp, a charge removal charger or the like is used, and the exposure light source and the charging means can be used, respectively. In addition, known processes can be used for reading, feeding, fixing, paper discharge and the like that are not close to the photoconductor.

(Process cartridge)
The process cartridge of the present invention includes an electrophotographic photosensitive member, a charging unit that charges the surface of the electrophotographic photosensitive member, an exposure unit that exposes the charged surface of the electrophotographic photosensitive member to form an electrostatic latent image, It comprises at least one of developing means for developing the electrostatic latent image with toner to form a visible image and transfer means for transferring the visible image to a recording medium. And other means.
The electrophotographic photosensitive member used in the process cartridge of the present invention is the above-described electrophotographic photosensitive member of the present invention.

  For example, as shown in FIG. 6, the process cartridge includes an electrophotographic photosensitive member 101, and at least one of a charging unit 102, a developing unit 104, a transfer unit 106, a cleaning unit 107, and a charge eliminating unit (not shown). And an apparatus (part) that can be attached to and detached from the image forming apparatus main body. Referring to the image forming process using the process cartridge of FIG. 6, the photosensitive member 101 is charged in the direction of the arrow while being charged by the charging unit 102 and exposed by the exposure unit 103. The electrostatic latent image is developed with toner by the developing unit 104, and the toner development is transferred to the recording medium 105 by the transfer unit 106 and printed out. Next, the surface of the photoconductor after the image transfer is cleaned by the cleaning unit 107 and further neutralized by a neutralizing unit (not shown), and the above operation is repeated again.

  EXAMPLES Next, although an Example and a comparative example are given and this invention is demonstrated more concretely, this invention is not restrict | limited to the following Example. In addition, all "parts" used in an Example represent a mass part.

Example 1
<Production of electrophotographic photoreceptor>
Undercoat layer coating solution A1 was prepared by the following method.
-Preparation of gallium-containing zinc oxide particles-
Gallium-containing zinc oxide particles were produced by the following method.
A slurry was prepared by mixing and stirring the following aqueous solution, and heated at 85 ° C. for 1 hour. The slurry was cooled to room temperature, filtered, washed with water, further washed with ethanol, dried, and then fired at 900 ° C. for 1 hour in a hydrogen gas atmosphere. The obtained fired product was crushed to obtain gallium-containing zinc oxide particles. As a result of analyzing the obtained gallium-containing zinc oxide particles with a fluorescent X-ray apparatus, the gallium content was 0.1% by mass with respect to zinc.
-Zinc sulfate aqueous solution (concentration of zinc sulfate is 10% by mass) ... 100 parts-Gallium sulfate aqueous solution (concentration of gallium sulfate is 10% by mass) ... 0.125 parts-Monoethanolamine aqueous solution (monoethanolamine Concentration is 3.75% by mass) ... 100 parts

The surface treatment of the obtained gallium-containing zinc oxide particles was performed by the following method.
The following materials were mixed and stirred for 2 hours. Then, toluene was distilled off under reduced pressure and baked at 120 ° C. for 3 hours to obtain gallium-containing surface-treated zinc oxide particles.
Gallium-containing zinc oxide particles: gallium-containing zinc oxide particles prepared by the above method: 100 parts Surface treatment agent: Silane coupling agent having an amino group (KBM573, manufactured by Shin-Etsu Chemical Co., Ltd.): 2 parts Solvent: tetrahydrofuran: 500 parts

Next, the following materials were mixed and stirred for 6 hours at 1,500 rpm using zirconia beads having a diameter of 0.5 mm and a vibration mill to prepare an undercoat layer coating solution A1.
-Gallium-containing surface-treated zinc oxide particles: 150 parts-Binder resin: Blocked isocyanate (Sumidule 3175, solid content 75% by mass, manufactured by Sumitomo Bayern Urethane Co., Ltd.) 60 parts and Butyral resin (BM-1, Sekisui Chemical Co., Ltd.) Made by dissolving 2-butanone in a 20% by mass solution: 225 parts Solvent: 2-butanone: 105 parts

A charge generation layer coating solution B was prepared by the method described below.
The following materials were mixed and stirred for 8 hours using a glass bead having a diameter of 1 mm and a bead mill to prepare a coating solution B for charge generation layer.
Charge generating material: titanyl phthalocyanine ... 8 parts Binder resin: polyvinyl butyral (Esrec BX-1, manufactured by Sekisui Chemical Co., Ltd.) ... 5 parts Solvent: 2-butanone ... 400 parts 2 shows a powder X-ray diffraction spectrum of the titanyl phthalocyanine.

A charge transport layer coating solution C was prepared by the method described below.
The following materials were mixed, and the charge transport layer coating solution C was prepared by stirring until all the materials were dissolved.
Charge transport material: Charge transport material represented by the following structural formula (1): 7 parts <Structural formula (1)>
Binder resin: Polycarbonate (TS-2050, manufactured by Teijin Chemicals) ... 10 parts Leveling agent: Silicone oil (KF-50, manufactured by Shin-Etsu Chemical Co., Ltd.): 0.0005 parts Solvent: Tetrahydrofuran・ 100 copies

  On the aluminum cylinder (diameter: 100 mm, length: 380 mm), the undercoat layer coating solution A1 is applied by dip coating, followed by drying at 170 ° C. for 30 minutes to laminate an undercoat layer having an average thickness of 30 μm. did. Next, the charge generation layer coating solution B was applied by a dip coating method, followed by drying at 90 ° C. for 30 minutes to laminate a charge generation layer having an average thickness of 0.2 μm. Further, the charge transport layer coating solution C was applied by dip coating, followed by drying at 150 ° C. for 30 minutes to laminate a charge transport layer having an average thickness of 25 μm. Thus, the photoreceptor of Example 1 was produced.

(Example 2)
<Production of electrophotographic photoreceptor>
A photoreceptor of Example 2 was produced in the same manner as in Example 1 except that the undercoat layer coating solution A2 prepared as follows was used and the average thickness of the undercoat layer was 25 μm.

-Preparation of gallium-containing zinc oxide particles-
Gallium-containing zinc oxide particles were produced by the following method.
The following aqueous solution was mixed and stirred to prepare a slurry, and heated at 85 ° C. for 1 hour. The slurry was cooled to room temperature, filtered, washed with water, further washed with ethanol, dried, and then fired at 900 ° C. for 1 hour in a hydrogen gas atmosphere. The obtained fired product was crushed to obtain gallium-containing zinc oxide particles. As a result of analyzing the obtained gallium-containing zinc oxide particles with a fluorescent X-ray apparatus, the gallium content was 0.1% by mass with respect to zinc.
-Zinc sulfate aqueous solution (concentration of zinc sulfate is 10% by mass) ... 100 parts-Gallium sulfate aqueous solution (concentration of gallium sulfate is 10% by mass) ... 0.125 parts-Monoethanolamine aqueous solution (monoethanolamine Concentration is 3.75% by mass) ... 100 parts

The surface treatment of the obtained gallium-containing zinc oxide particles was performed by the following method.
The following materials were mixed and stirred for 2 hours. Then, toluene was distilled off under reduced pressure and baked at 120 ° C. for 3 hours to obtain gallium-containing surface-treated zinc oxide particles.
Gallium-containing zinc oxide particles: gallium-containing zinc oxide particles prepared by the above method: 100 parts Surface treatment agent: Silane coupling agent having an amino group (KBE903, manufactured by Shin-Etsu Chemical Co., Ltd.): 2 parts Solvent: tetrahydrofuran: 500 parts

Next, the following materials were mixed and stirred for 6 hours at 1500 rpm using zirconia beads having a diameter of 0.5 mm and a vibration mill to prepare an undercoat layer coating solution A2.
-Gallium-containing surface-treated zinc oxide particles: 100 parts-Binder resin: Blocked isocyanate (Sumidule 3175 (solid content concentration 75% by mass), manufactured by Sumitomo Bayern Urethane Co., Ltd.) 60 parts, and butyral resin (BM-1, (Sekisui Chemical Co., Ltd.) dissolved in 2-butanone in a 20% by mass solution: 225 parts Solvent: 2-butanone: 105 parts

(Example 3)
<Production of electrophotographic photoreceptor>
A photoreceptor of Example 3 was produced in the same manner as in Example 1 except that the undercoat layer coating solution A3 prepared as follows was used and the average thickness of the undercoat layer was changed to 20 μm.

-Preparation of gallium-containing zinc oxide particles-
Gallium-containing zinc oxide particles were produced by the following method.
The following aqueous solution was mixed and stirred to prepare a slurry, and heated at 85 ° C. for 1 hour. The slurry was cooled to room temperature, filtered, washed with water, further washed with ethanol, dried, and then fired at 900 ° C. for 1.5 hours in a hydrogen gas atmosphere. The obtained fired product was crushed to obtain gallium-containing zinc oxide particles. As a result of analyzing the obtained gallium-containing zinc oxide particles with a fluorescent X-ray apparatus, the gallium content was 0.1% by mass with respect to zinc.
-Zinc sulfate aqueous solution (concentration of zinc sulfate is 10% by mass) ... 100 parts-Gallium sulfate aqueous solution (concentration of gallium sulfate is 10% by mass) ... 0.125 parts-Monoethanolamine aqueous solution (monoethanolamine Concentration is 3.75% by mass) ... 100 parts

The surface treatment of the obtained gallium-containing zinc oxide particles was performed by the following method.
The following materials were mixed and stirred for 2 hours. Then, toluene was distilled off under reduced pressure and baked at 120 ° C. for 3 hours to obtain gallium-containing surface-treated zinc oxide particles.
Gallium-containing zinc oxide particles: gallium-containing zinc oxide particles prepared by the above method: 100 parts Surface treatment agent: Silane coupling agent having an amino group (KBM603, manufactured by Shin-Etsu Chemical Co., Ltd.): 2 parts Solvent: tetrahydrofuran: 500 parts

Next, the following materials were mixed and stirred for 6 hours at 1,500 rpm using zirconia beads having a diameter of 0.5 mm and a vibration mill to prepare an undercoat layer coating solution A3.
-Gallium-containing surface-treated zinc oxide particles: 100 parts-Binder resin: Blocked isocyanate (Sumidule 3175 (solid content concentration 75% by mass), manufactured by Sumitomo Bayern Urethane Co., Ltd.) 60 parts, and butyral resin (BM-1, (Sekisui Chemical Co., Ltd.) dissolved in 2-butanone in a 20% by mass solution: 225 parts Solvent: 2-butanone: 105 parts

Example 4
<Production of electrophotographic photoreceptor>
A photoreceptor of Example 4 was produced in the same manner as in Example 1 except that the undercoat layer coating solution A4 prepared as follows was used and the average thickness of the undercoat layer was changed to 15 μm.

-Preparation of gallium-containing zinc oxide particles-
Gallium-containing zinc oxide particles were produced by the following method.
The following aqueous solution was mixed and stirred to prepare a slurry, and heated at 85 ° C. for 1 hour. The slurry was cooled to room temperature, filtered, washed with water, further washed with ethanol, dried, and then fired at 1,000 ° C. for 1 hour in a hydrogen gas atmosphere. The obtained fired product was crushed to obtain gallium-containing zinc oxide particles. As a result of analyzing the obtained gallium-containing zinc oxide particles with a fluorescent X-ray apparatus, the gallium content was 0.1% by mass with respect to zinc.
-Zinc sulfate aqueous solution (concentration of zinc sulfate is 10% by mass) ... 100 parts-Gallium sulfate aqueous solution (concentration of gallium sulfate is 10% by mass) ... 0.125 parts-Monoethanolamine aqueous solution (monoethanolamine Concentration is 3.75% by mass) ... 100 parts

The surface treatment of the obtained gallium-containing zinc oxide particles was performed by the following method.
The following materials were mixed and stirred for 2 hours. Then, toluene was distilled off under reduced pressure and baked at 120 ° C. for 3 hours to obtain gallium-containing surface-treated zinc oxide particles.
・ Gallium-containing zinc oxide particles: gallium-containing zinc oxide particles produced by the above method: 100 parts ・ Surface treatment agent: Silane coupling agent having no amino group (KBM503, manufactured by Shin-Etsu Chemical Co., Ltd.) ... 2 Parts ・ Solvent: Tetrahydrofuran ... 500 parts

Next, the following materials were mixed and stirred for 6 hours at 1,500 rpm using zirconia beads having a diameter of 0.5 mm and a vibration mill to prepare a coating solution A4 for an undercoat layer.
-Gallium-containing surface-treated zinc oxide particles: 70 parts-Binder resin: Blocked isocyanate (Sumidule 3175 (solid content concentration 75 mass%), manufactured by Sumitomo Bayern Urethane Co., Ltd.) 60 parts, and butyral resin (BM-1, (Sekisui Chemical Co., Ltd.) dissolved in 2-butanone in a 20% by mass solution: 225 parts Solvent: 2-butanone: 105 parts

(Example 5)
<Production of electrophotographic photoreceptor>
A photoreceptor of Example 5 was produced in the same manner as in Example 1 except that the undercoat layer coating solution A5 prepared as follows was used and the average thickness of the undercoat layer was changed to 10 μm.

-Preparation of gallium-containing zinc oxide particles-
Gallium-containing zinc oxide particles were produced by the following method.
The following aqueous solution was mixed and stirred to prepare a slurry, and heated at 95 ° C. for 1 hour. The slurry was cooled to room temperature, filtered, washed with water, further washed with ethanol, dried, and then fired at 800 ° C. for 1 hour in a hydrogen gas atmosphere. The obtained fired product was crushed to obtain gallium-containing zinc oxide particles. As a result of analyzing the obtained gallium-containing zinc oxide particles with a fluorescent X-ray apparatus, the gallium content was 4.0% by mass with respect to zinc.
-Zinc sulfate aqueous solution (concentration of zinc sulfate is 10% by mass) ... 100 parts-Gallium sulfate aqueous solution (concentration of gallium sulfate is 10% by mass) ... 2 parts-Monoethanolamine aqueous solution (concentration of monoethanolamine is 3.75% by mass) ... 100 parts

Next, the following materials were mixed and stirred for 6 hours at 1,500 rpm using zirconia beads having a diameter of 0.5 mm and a vibration mill to prepare an undercoat layer coating solution A5.
-Gallium-containing zinc oxide particles: 50 parts-Binder resin: Blocked isocyanate (Sumidule 3175 (solid content concentration 75 mass%), manufactured by Sumitomo Bayern Urethane Co., Ltd.) 60 parts, and butyral resin (BM-1, Sekisui Chemical) 20% by mass dissolved in 2-butanone 225 parts ・ Solvent: 2-butanone 105 parts

(Example 6)
<Production of electrophotographic photoreceptor>
A photoreceptor of Example 6 was obtained in the same manner as in Example 1 except that the undercoat layer coating solution A6 prepared as follows was used and the average thickness of the undercoat layer was changed to 15 μm.

-Preparation of gallium-containing zinc oxide particles-
Gallium-containing zinc oxide particles were produced by the following method.
The following aqueous solution was mixed and stirred to prepare a slurry, and heated at 95 ° C. for 1 hour. The slurry was cooled to room temperature, filtered, washed with water, further washed with ethanol, dried, and then fired at 800 ° C. for 1.5 hours in a hydrogen gas atmosphere. The obtained fired product was crushed to obtain gallium-containing zinc oxide particles. As a result of analyzing the obtained gallium-containing zinc oxide particles with a fluorescent X-ray apparatus, the gallium content was 4.0% by mass with respect to zinc.
-Zinc sulfate aqueous solution (concentration of zinc sulfate is 10% by mass) ... 100 parts-Gallium sulfate aqueous solution (concentration of gallium sulfate is 10% by mass) ... 2 parts-Monoethanolamine aqueous solution (concentration of monoethanolamine is 3.75% by mass) ... 100 parts

Next, the following materials were mixed and stirred for 6 hours at 1,500 rpm using zirconia beads having a diameter of 0.5 mm and a vibration mill to prepare an undercoat layer coating solution A6.
-Gallium-containing zinc oxide particles: 70 parts-Binder resin: Blocked isocyanate (Sumidule 3175 (solid content concentration 75% by mass), manufactured by Sumitomo Bayern Urethane Co., Ltd.) 60 parts, and butyral resin (BM-1, Sekisui Chemical) 20% by mass dissolved in 2-butanone 225 parts ・ Solvent: 2-butanone 105 parts

(Example 7)
<Production of electrophotographic photoreceptor>
A photoreceptor of Example 7 was produced in the same manner as in Example 1 except that the undercoat layer coating solution A7 prepared as follows was used and the average thickness of the undercoat layer was changed to 5 μm.

-Preparation of gallium-containing zinc oxide particles-
Gallium-containing zinc oxide particles were produced by the following method.
The following aqueous solution was mixed and stirred to prepare a slurry, and heated at 95 ° C. for 1 hour. The slurry was cooled to room temperature, filtered, washed with water, further washed with ethanol, dried, and then fired at 900 ° C. for 1 hour in a hydrogen gas atmosphere. The obtained fired product was crushed to obtain gallium-containing zinc oxide particles. As a result of analyzing the obtained gallium-containing zinc oxide particles with a fluorescent X-ray apparatus, the gallium content was 0.02 mass% with respect to zinc.
・ Zinc sulfate aqueous solution (concentration of zinc sulfate is 10 mass%) ... 100 parts ・ Gallium sulfate aqueous solution (concentration of gallium sulfate is 10 mass%) ... 0.02 parts Concentration is 3.75% by mass) ... 100 parts

Next, the following materials were mixed and stirred for 6 hours at 1500 rpm using a zirconia bead having a diameter of 0.5 mm and a vibration mill to prepare an undercoat layer coating solution A7.
-Gallium-containing zinc oxide particles: 100 parts-Binder resin: Blocked isocyanate (Sumidule 3175 (solid content concentration 75% by mass), manufactured by Sumitomo Bayern Urethane Co., Ltd.) 60 parts, and butyral resin (BM-1, Sekisui Chemical) 20% by mass dissolved in 2-butanone 225 parts ・ Solvent: 2-butanone 105 parts

(Example 8)
<Production of electrophotographic photoreceptor>
A photoreceptor of Example 8 was produced in the same manner as in Example 1 except that the undercoat layer coating solution A8 prepared as follows was used and the average thickness of the undercoat layer was changed to 15 μm.

-Preparation of gallium-containing zinc oxide particles-
Gallium-containing zinc oxide particles were produced by the following method.
The following aqueous solution was mixed and stirred to prepare a slurry, and heated at 85 ° C. for 1 hour. The slurry was cooled to room temperature, filtered, washed with water, further washed with ethanol, dried, and then fired at 700 ° C. for 1 hour in a hydrogen gas atmosphere. The obtained fired product was crushed to obtain gallium-containing zinc oxide particles. As a result of analyzing the obtained gallium-containing zinc oxide particles with a fluorescent X-ray apparatus, the gallium content was 0.1% by mass with respect to zinc.
-Zinc sulfate aqueous solution (concentration of zinc sulfate is 10% by mass) ... 100 parts-Gallium sulfate aqueous solution (concentration of gallium sulfate is 10% by mass) ... 0.125 parts-Monoethanolamine aqueous solution (monoethanolamine Concentration is 3.75% by mass) ... 100 parts

Next, the following materials were mixed and stirred for 6 hours at 1500 rpm using a zirconia bead having a diameter of 0.5 mm and a vibration mill to prepare an undercoat layer coating solution A8.
-Gallium-containing zinc oxide particles: 100 parts-Binder resin: Blocked isocyanate (Sumidule 3175 (solid content concentration 75% by mass), manufactured by Sumitomo Bayern Urethane Co., Ltd.) 60 parts, and butyral resin (BM-1, Sekisui Chemical) 20% by mass dissolved in 2-butanone 225 parts ・ Solvent: 2-butanone 105 parts

Example 9
<Production of electrophotographic photoreceptor>
A photoreceptor of Example 9 was produced in the same manner as in Example 1 except that the undercoat layer coating solution A9 prepared as follows was used and the average thickness of the undercoat layer was set to 35 μm.

-Preparation of gallium-containing zinc oxide particles-
Gallium-containing zinc oxide particles were produced by the following method.
The following aqueous solution was mixed and stirred to prepare a slurry, and heated at 95 ° C. for 1 hour. The slurry was cooled to room temperature, filtered, washed with water, further washed with ethanol, dried, and then fired at 900 ° C. for 1 hour in a hydrogen gas atmosphere. The obtained fired product was crushed to obtain gallium-containing zinc oxide particles. As a result of analyzing the obtained gallium-containing zinc oxide particles with a fluorescent X-ray apparatus, the gallium content was 0.02 mass% with respect to zinc.
・ Zinc sulfate aqueous solution (concentration of zinc sulfate is 10 mass%) ... 100 parts ・ Gallium sulfate aqueous solution (concentration of gallium sulfate is 10 mass%) ... 0.02 parts Concentration is 3.75% by mass) ... 100 parts

Next, the following materials were mixed and stirred for 6 hours at 1,500 rpm using zirconia beads having a diameter of 0.5 mm and a vibration mill to prepare a coating solution A9 for an undercoat layer.
-Gallium-containing zinc oxide particles: 300 parts-Binder resin: Blocked isocyanate (Sumijoule 3175 (solid content concentration 75 mass%), manufactured by Sumitomo Bayern Urethane Co., Ltd.) 60 parts, and butyral resin (BM-1, Sekisui Chemical) 20% by mass dissolved in 2-butanone 225 parts ・ Solvent: 2-butanone 105 parts

(Example 10)
<Production of electrophotographic photoreceptor>
A photoreceptor of Example 10 was produced in the same manner as in Example 1 except that the undercoat layer coating solution A10 prepared as follows was used and the average thickness of the undercoat layer was set to 35 μm.

-Preparation of gallium-containing zinc oxide particles-
Gallium-containing zinc oxide particles were produced by the following method.
The following aqueous solution was mixed and stirred to prepare a slurry, and heated at 95 ° C. for 1 hour. The slurry was cooled to room temperature, filtered, washed with water, further washed with ethanol, dried, and then fired at 1,000 ° C. for 1.5 hours in a hydrogen gas atmosphere. The obtained fired product was crushed to obtain gallium-containing zinc oxide particles. As a result of analyzing the obtained gallium-containing zinc oxide particles with a fluorescent X-ray apparatus, the gallium content was 4.0% by mass with respect to zinc.
-Zinc sulfate aqueous solution (concentration of zinc sulfate is 10% by mass) ... 100 parts-Gallium sulfate aqueous solution (concentration of gallium sulfate is 10% by mass) ... 2 parts-Monoethanolamine aqueous solution (concentration of monoethanolamine is 3.75% by mass) ... 100 parts

Next, the following materials were mixed and stirred for 6 hours at 1500 rpm using zirconia beads having a diameter of 0.5 mm and a vibration mill to prepare an undercoat layer coating solution A10.
-Gallium-containing zinc oxide particles: 300 parts-Binder resin: Blocked isocyanate (Sumijoule 3175 (solid content concentration 75 mass%), manufactured by Sumitomo Bayern Urethane Co., Ltd.) 60 parts, and butyral resin (BM-1, Sekisui Chemical) 20% by mass dissolved in 2-butanone 225 parts ・ Solvent: 2-butanone 105 parts

(Comparative Example 1)
<Production of electrophotographic photoreceptor>
A photoreceptor of Comparative Example 1 was produced in the same manner as in Example 1 except that the undercoat layer coating solution A11 prepared as described below was used and the average thickness of the undercoat layer was changed to 15 μm.

-Preparation of gallium-containing zinc oxide particles-
Gallium-containing zinc oxide particles were produced by the following method.
The following aqueous solution was mixed and stirred to prepare a slurry, and heated at 85 ° C. for 1 hour. The slurry was cooled to room temperature, filtered, washed with water, further washed with ethanol, dried, and then fired at 900 ° C. for 1 hour in a hydrogen gas atmosphere. The obtained fired product was crushed to obtain gallium-containing zinc oxide particles. As a result of analyzing the obtained gallium-containing zinc oxide particles with a fluorescent X-ray apparatus, the gallium content was 0.1% by mass with respect to zinc.
-Zinc sulfate aqueous solution (concentration of zinc sulfate is 10% by mass) ... 100 parts-Gallium sulfate aqueous solution (concentration of gallium sulfate is 10% by mass) ... 0.125 parts-Monoethanolamine aqueous solution (monoethanolamine Concentration is 3.75% by mass) ... 100 parts

The surface treatment of the obtained gallium-containing zinc oxide particles was performed by the following method.
The following materials were mixed and stirred for 2 hours. Then, toluene was distilled off under reduced pressure and baked at 120 ° C. for 3 hours to obtain gallium-containing surface-treated zinc oxide particles.
Gallium-containing zinc oxide particles: gallium-containing zinc oxide particles prepared by the above method: 100 parts Surface treatment agent: Silane coupling agent having an amino group (KBM603, manufactured by Shin-Etsu Chemical Co., Ltd.): 2 parts Solvent: tetrahydrofuran: 500 parts

Next, the following materials were mixed and stirred for 1 hour at 1500 rpm using zirconia beads having a diameter of 0.5 mm and a vibration mill to prepare an undercoat layer coating solution A11.
-Gallium-containing surface-treated zinc oxide particles: 100 parts-Binder resin: Blocked isocyanate (Sumidule 3175 (solid content concentration 75% by mass), manufactured by Sumitomo Bayern Urethane Co., Ltd.) 60 parts, and butyral resin (BM-1, (Sekisui Chemical Co., Ltd.) dissolved in 2-butanone in a 20% by mass solution: 225 parts Solvent: 2-butanone: 105 parts

(Comparative Example 2)
<Production of electrophotographic photoreceptor>
A photoreceptor of Comparative Example 2 was obtained in the same manner as in Example 1 except that the undercoat layer coating solution A12 prepared as follows was used and the average thickness of the undercoat layer was changed to 15 μm.

-Production of aluminum-containing zinc oxide particles-
Aluminum-containing zinc oxide particles were produced by the following method.
The following aqueous solution was mixed and stirred to prepare a slurry, and heated at 95 ° C. for 1 hour. The slurry was cooled to room temperature, filtered, washed with water, further washed with ethanol, dried, and then fired at 900 ° C. for 1 hour in a hydrogen gas atmosphere. The obtained fired product was crushed to obtain aluminum-containing zinc oxide particles.
As a result of analyzing the obtained aluminum-containing zinc oxide particles with a fluorescent X-ray apparatus, the aluminum content was 0.1% by mass with respect to zinc.
-Aqueous solution of zinc sulfate (concentration of zinc sulfate 10 mass%) ... 100 parts-Aqueous solution of aluminum sulfate (concentration of aluminum sulfate 10 mass%) ... 0.26 parts-Aqueous solution of monoethanolamine (monoethanolamine) Concentration of 3.75% by mass) ... 100 parts

The surface treatment of the obtained aluminum-containing zinc oxide particles was performed by the following method.
The following materials were mixed and stirred for 2 hours. Then, toluene was distilled off under reduced pressure and baked at 120 ° C. for 3 hours to obtain aluminum-containing surface-treated zinc oxide particles.
Aluminum-containing zinc oxide particles: aluminum-containing zinc oxide particles prepared by the above method ... 100 parts Surface treatment agent: Silane coupling agent having an amino group (KBM603, Shin-Etsu Chemical Co., Ltd.) ... 2 parts Solvent: tetrahydrofuran: 500 parts

Next, the following materials were mixed and stirred for 6 hours at 1,500 rpm using zirconia beads having a diameter of 0.5 mm and a vibration mill to prepare an undercoat layer coating solution A12.
-Aluminum-containing surface-treated zinc oxide particles: 100 parts-Binder resin: Blocked isocyanate (Sumidule 3175 (solid content concentration 75% by mass), manufactured by Sumitomo Bayern Urethane Co., Ltd.) 60 parts, and butyral resin (BM-1, (Sekisui Chemical Co., Ltd.) dissolved in 2-butanone in a 20% by mass solution: 225 parts Solvent: 2-butanone: 105 parts

(Comparative Example 3)
<Production of electrophotographic photoreceptor>
A photoreceptor of Comparative Example 3 was produced in the same manner as in Example 1 except that the undercoat layer coating solution A13 prepared as follows was used and the average thickness of the undercoat layer was changed to 15 μm.

-Production of zinc oxide particles-
Zinc oxide particles were produced by the following method.
The following aqueous solution was mixed and stirred to prepare a slurry, and heated at 95 ° C. for 1 hour. The slurry was cooled to room temperature, filtered, washed with water, further washed with ethanol, dried, and then fired at 900 ° C. for 1 hour in a hydrogen gas atmosphere. The obtained fired product was crushed to obtain zinc oxide particles.
-Aqueous solution of zinc sulfate (concentration of zinc sulfate 10 mass%) ... 100 parts-Aqueous solution of monoethanolamine (concentration of monoethanolamine 3.75 mass%) ... 100 parts

The surface treatment of the obtained zinc oxide particles was performed by the following method.
The following materials were mixed and stirred for 2 hours. Thereafter, toluene was distilled off under reduced pressure and baked at 120 ° C. for 3 hours to obtain surface-treated zinc oxide particles.
-Zinc oxide particles: Zinc oxide particles prepared by the above method ... 100 parts-Surface treatment agent: Silane coupling agent having an amino group (KBM603, manufactured by Shin-Etsu Chemical Co., Ltd.) ... 2 parts-Solvent: Tetrahydrofuran ..500 copies

Next, the following materials were mixed and stirred for 6 hours at 1,500 rpm using zirconia beads having a diameter of 0.5 mm and a vibration mill to prepare a coating solution A13 for an undercoat layer.
-Surface treated zinc oxide particles: 100 parts-Binder resin: Blocked isocyanate (Sumidule 3175 (solid content concentration 75% by mass), manufactured by Sumitomo Bayern Urethane Co., Ltd.) 60 parts and Butyral resin (BM-1, Sekisui Chemical) 20% by mass dissolved in 2-butanone 225 parts ・ Solvent: 2-butanone 105 parts

  Next, various characteristics of each of the produced photoreceptors were evaluated as follows. The results are shown in Tables 1 and 2.

<Average particle size of zinc oxide particles>
The average particle diameter of the zinc oxide particles was determined by arbitrarily observing 100 particles observed in the undercoat layer of each photoconductor with a transmission electron microscope (TEM), and determining the projected area. The equivalent circle diameter was calculated to determine the particle diameter, and the average value was taken as the average particle diameter.

<Measurement of specular reflectance of undercoat layer>
For each photoconductor, the charge generation layer and the charge transport layer were dissolved or peeled using a solvent, and a sample in which only the undercoat layer was laminated on the support was prepared. Each layer was dissolved or peeled off by wiping the charge generation layer with a soft cloth (cotton) moistened with tetrahydrofuran, and immersing the charge transport layer in 2-butanone for a predetermined time.
A spectrophotometer UV-3600 (Shimadzu Co., Ltd.) equipped with a multipurpose large sample chamber unit MPC-3100 (manufactured by Shimadzu Corporation) was used for the sample in which only the obtained undercoat layer was laminated on the support. The specular reflectance of each undercoat layer at an incident light wavelength of 800 nm and an incident light of 8 ° was measured.
Cut the sample with only the support layer and the undercoat layer stacked on the support layer to an appropriate size. First, set the support layer with nothing stacked on the measuring device. After performing the line correction, the sample in a state where only the undercoat layer was laminated on the support was set on a measuring apparatus, and the specular reflectance was measured. The sample was evaluated according to the following evaluation criteria.
[Evaluation criteria]
A: The specular reflectance of the undercoat layer is 80% or more. ○: The specular reflectance of the undercoat layer is 70% or more and less than 80%. X: The specular reflectance of the undercoat layer is less than 70%.

<Photoreceptor characteristics>
<< Evaluation equipment >>
Using a remodeling machine of Ricoh Co., Ltd. (RICOH ProC900), using a scorotron charging member (discharge wire is a tungsten-molybdenum alloy plated with 50 μm in diameter) as a charging member, and 780 nm as an image exposure light source LD light (image writing by a polygon mirror, resolution 1,200 dpi) was used, development was performed by two-component development using black toner, a transfer belt was used as a transfer member, and a charge removal lamp was used for charge removal.

<< Photoconductor degradation test >>
As a photoreceptor deterioration test, 250,000 sheets of black single color test charts (image area ratio 5%) were continuously output at 23 ° C. in a normal temperature and humidity environment of 55% RH.

<< Electrical Characteristic Evaluation (Chargeability and Residual Potential) >>
The surface potential of the photoconductor was measured before and after the photoconductor degradation test. The potential measurement was performed by the following method by attaching a potential sensor obtained by modifying the developing unit of the evaluation apparatus and setting the unit in the evaluation apparatus.
The applied voltage to the wire is −1,800 μA, the grid voltage is −800 V, and the charging potential (VD) and post-exposure potential on the 10th sheet when 10 sheets of all solid images are printed in the vertical direction on A3 size paper ( VL) was measured. For the measurement, a surface potential meter (MODEL 344 surface potential meter, manufactured by Trek Japan Co., Ltd.) was used, and the numerical value of the surface potential meter was recorded with an oscilloscope at 100 signals per second or more and evaluated according to the following criteria.
[Chargeability]
A: The charging potential difference (ΔVD) before and after the photoreceptor deterioration test is less than 10 V. ○: The charging potential difference (ΔVD) before and after the photoreceptor deterioration test is 10 V or more and less than 30 V. X: The charging potential difference (ΔVD) before and after the photoreceptor deterioration test is 30 V. [Residual potential]
A: Post-exposure potential difference (ΔVL) before and after the photoconductor deterioration test is less than 10 V. O: Post-exposure potential difference (ΔVL) before and after the photoconductor deterioration test is 10 V or more and less than 30 V. X: Post-exposure potential difference before and after the photoconductor deterioration test (ΔVL) ) 30V or more

<Image evaluation>
Images were output before and after the photoreceptor deterioration test, and afterimage evaluation and background contamination evaluation were performed.
Regarding afterimage evaluation, three images having a 3 cm × 3 cm x-shaped pattern were output continuously, then three halftone outputs were performed continuously, and the presence or absence of afterimage generation was visually confirmed.
With respect to the background stain evaluation, glossy coated paper was used to output five continuous white background images, and the presence or absence of the background stain was evaluated.

As an aspect of this invention, it is as follows, for example.
<1> An electrophotographic photoreceptor having at least a support and an undercoat layer and a photosensitive layer in this order on the support,
The undercoat layer contains at least gallium-containing zinc oxide particles and a binder resin;
The electrophotographic photoreceptor, wherein the undercoat layer has a specular reflectance of 70% or more with respect to incident light having a wavelength of 800 nm.
<2> The electrophotographic photosensitive member according to <1>, wherein the gallium-containing zinc oxide particles have an average particle diameter of 20 nm to 200 nm.
<3> The electrophotographic photosensitive member according to any one of <1> to <2>, wherein the undercoat layer has an average thickness of 10 μm to 30 μm.
<4> The electrophotographic photosensitive member according to any one of <1> to <3>, wherein the content of the gallium-containing zinc oxide particles in the undercoat layer is 30% by mass to 60% by mass.
<5> The electrophotographic photosensitive member according to any one of <1> to <4>, wherein the gallium-containing zinc oxide particles are surface-treated with a silane coupling agent.
<6> The electrophotographic photosensitive member according to <5>, wherein the silane coupling agent has an amino group.
<7> An electrophotographic photosensitive member, a charging unit that charges the surface of the electrophotographic photosensitive member, an exposure unit that exposes the charged surface of the electrophotographic photosensitive member to form an electrostatic latent image, and the electrostatic An image forming apparatus having at least developing means for developing a latent image by using toner to form a visible image and transfer means for transferring the visible image to a recording medium,
An electrophotographic photosensitive member according to any one of <1> to <6>, wherein the electrophotographic photosensitive member is an image forming apparatus.
<8> An electrophotographic photosensitive member, charging means for charging the surface of the electrophotographic photosensitive member, exposure means for exposing the charged surface of the electrophotographic photosensitive member to form an electrostatic latent image, and the electrostatic latent image A developing unit for developing a visible image by using toner, and at least one unit selected from a transfer unit for transferring the visible image to a recording medium,
A process cartridge, wherein the electrophotographic photosensitive member is the electrophotographic photosensitive member according to any one of <1> to <6>.
<9> A charging step for charging the surface of the electrophotographic photosensitive member, an exposure step for exposing the charged surface of the electrophotographic photosensitive member to form an electrostatic latent image, and the electrostatic latent image using toner. An image forming method comprising at least a development step of developing to form a visible image and a transfer step of transferring the visible image to a recording medium,
The electrophotographic photosensitive member is the electrophotographic photosensitive member according to any one of <1> to <6>, wherein the electrophotographic photosensitive member is an image forming method.

31 Support 32 Subbing Layer 33 Single-Layer Type Photosensitive Layer 35 Charge Generation Layer 37 Charge Transport Layer 39 Protective Layer

JP 2003-98705 A JP 2007-047467 A Japanese Patent Laid-Open No. 2003-084472 JP 2006-30700 A JP 2007-322669 A JP 2012-18370 A

Claims (8)

An electrophotographic photoreceptor having at least a support, and an undercoat layer and a photosensitive layer in this order on the support,
The undercoat layer contains at least gallium-containing zinc oxide particles and a binder resin;
An electrophotographic photoreceptor, wherein the undercoat layer has a specular reflectance of 70% or more with respect to incident light having a wavelength of 800 nm.   The electrophotographic photosensitive member according to claim 1, wherein the gallium-containing zinc oxide particles have an average particle diameter of 20 nm to 200 nm.   The electrophotographic photosensitive member according to claim 1, wherein an average thickness of the undercoat layer is 10 μm to 30 μm.   The electrophotographic photosensitive member according to any one of claims 1 to 3, wherein a content of the gallium-containing zinc oxide particles in the undercoat layer is 30% by mass to 60% by mass.   The electrophotographic photosensitive member according to claim 1, wherein the gallium-containing zinc oxide particles are surface-treated with a silane coupling agent.   The electrophotographic photosensitive member according to claim 5, wherein the silane coupling agent has an amino group. An electrophotographic photosensitive member; charging means for charging the surface of the electrophotographic photosensitive member; exposure means for exposing the charged surface of the electrophotographic photosensitive member to form an electrostatic latent image; and An image forming apparatus comprising at least a developing unit that develops a visible image by developing with toner and a transfer unit that transfers the visible image to a recording medium,
An image forming apparatus, wherein the electrophotographic photosensitive member is the electrophotographic photosensitive member according to claim 1. An electrophotographic photosensitive member; charging means for charging the surface of the electrophotographic photosensitive member; exposure means for exposing the charged surface of the electrophotographic photosensitive member to form an electrostatic latent image; A process cartridge having developing means for developing a visible image by using and at least one means selected from transfer means for transferring the visible image to a recording medium,
7. A process cartridge, wherein the electrophotographic photosensitive member is the electrophotographic photosensitive member according to claim 1.