JP6658155B2 - Electrophotographic photosensitive member, process cartridge, and image forming apparatus - Google Patents

Description

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

  In a conventional electrophotographic image forming apparatus, a toner image formed on the surface of an electrophotographic photosensitive member is transferred to a recording medium through processes of charging, forming an electrostatic latent image, developing, and transferring.

For example, Patent Literature 1 discloses “an electrophotographic photoconductor in which toner remaining on the surface of a photoconductor after a transfer process is removed by a fur brush, wherein the electrophotographic photoconductor has a photosensitive layer formed on a supporting substrate. An electrophotographic photoreceptor, wherein the photosensitive layer contains a charge generating agent in the vicinity of the surface, and the layer containing the charge generating agent has an absorbance of 0.3 or more per 1 μm of film thickness with respect to an exposure wavelength. . "Is disclosed.
Patent Document 2 discloses a “laminated photosensitive layer in which a charge generating layer containing at least a charge generating substance and a charge transporting layer containing a charge transporting substance are laminated in this order on an undercoat layer provided on a conductive substrate. Or an electrophotographic photosensitive member in which a single-layer type photosensitive layer containing a charge generating substance and a charge transporting substance is laminated, wherein the undercoat layer contains metal oxide fine particles and a binder resin, and the outermost surface of the photosensitive body The layer contains at least a charge transport material, a binder resin, and specific tetrafluoroethylene resin fine particles, and the binder resin in the outermost surface layer is a charge transport layer excluding the specific tetrafluoroethylene resin fine particles. An electrophotographic photoreceptor characterized by exhibiting a surface free energy value in the range of 25 to 35 mJ / mm ² in a charge transport layer formed using a coating liquid for use.

JP 2003-228183 A JP 2015-114350 A

  An object of the present invention is to provide a photoconductor having a single-layer photosensitive layer including a binder resin, a charge generation material, a hole transport material, and an electron transport material represented by the general formula (1). Electrophotography that suppresses the generation of color points that occur when an image is formed, as compared to the case where the photosensitive layer has a surface free energy of less than 24 mN / m or more than 30 mN / m when the outer peripheral surface of the photosensitive layer is measured. It is to provide a photoreceptor.

The above problem is solved by the following means. That is,
The invention according to < 1 > ,
A conductive substrate;
A single-layer photosensitive layer provided on the conductive substrate, wherein the binder resin, the charge generation material, the hole transport material, and the electron transport material represented by the following general formula (1): A photosensitive layer having a surface free energy of 24 mN / m or more and 30 mN / m or less when measuring the outer peripheral surface side of the photosensitive layer;
An electrophotographic photosensitive member having:


(In the general formula (1), R ¹¹ , R ¹² , R ¹³ , R ¹⁴ , R ¹⁵ , R ¹⁶ , and R ¹⁷ each independently represent a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group, an aryl group, R ¹⁸ represents an alkyl group, an aryl group, or an aralkyl group.)

The invention according to < 2 > ,
2. The electrophotographic photosensitive member according to < 1, wherein the photosensitive layer has a surface roughness Sa of 4.5 nm or more and 6.0 nm or less.

The invention according to <3> ,
Provided with the electrophotographic photosensitive member according to <1> or <2> ,
A process cartridge that is attached to and detached from the image forming apparatus.

The invention according to <4> ,
An electrophotographic photosensitive member according to <1> or <2> ,
Charging means for charging the surface of the electrophotographic photoreceptor,
Electrostatic latent image forming means for forming an electrostatic latent image on the surface of the charged electrophotographic photosensitive member,
Developing means for developing the electrostatic latent image formed on the surface of the electrophotographic photoreceptor to form a toner image with a developer containing toner;
Transfer means for transferring the toner image to the surface of a recording medium,
An image forming apparatus comprising:

According to the invention according to < 1 > , there is provided a single-layer photosensitive layer including a binder resin, a charge generation material, a hole transport material, and an electron transport material represented by the general formula (1). Compared to the case where the photoreceptor has a photosensitive layer having a surface free energy of less than 24 mN / m or more than 30 mN / m when the outer peripheral surface side of the photosensitive layer is measured, generation of a color point caused when an image is formed is reduced. An electrophotographic photoreceptor is provided that suppresses.

According to the invention according to < 2 > , compared with the case where the surface roughness Sa of the photosensitive layer is less than 4.5 nm or more than 6.0 nm, the electrophotographic photosensitive member that suppresses the generation of a color point that occurs when an image is formed. A body is provided.

According to the invention according to <3> or <4> , a single-layer type including a binder resin, a charge generation material, a hole transport material, and an electron transport material represented by the general formula (1) is provided. In the photoreceptor having a photosensitive layer, the surface free energy measured on the outer peripheral surface side of the photosensitive layer is less than 24 mN / m or more than 30 mN / m. The present invention provides a process cartridge or an image forming apparatus that suppresses the occurrence of a color point that occurs when forming an image.

FIG. 2 is a schematic partial cross-sectional view illustrating the electrophotographic photosensitive member according to the exemplary embodiment. It is a schematic structure figure showing the dip coating device in this embodiment. FIG. 1 is a schematic configuration diagram illustrating an image forming apparatus according to an embodiment. FIG. 9 is a schematic configuration diagram illustrating an image forming apparatus according to another embodiment.

  Hereinafter, an embodiment which is an example of the present invention will be described in detail.

<Electrophotographic photoreceptor>
The electrophotographic photoreceptor according to the present embodiment is a conductive substrate, a single-layer type photosensitive layer provided on the conductive substrate, a binder resin, a charge generation material, a hole transport material, and a general formula A photosensitive layer containing the electron transporting material represented by (1).
The photosensitive layer has a surface free energy of 24 mN / m or more and 30 mN / m or less when the surface free energy of the photosensitive layer measured on the outer peripheral surface side (hereinafter, also referred to as “surface free energy of the photosensitive layer on the outer peripheral surface side”) is measured. is there.

2. Description of the Related Art Conventionally, as an electrophotographic photoreceptor (hereinafter, also referred to as a “photoreceptor”), a photoreceptor having a single-layer type photosensitive layer (single-layer type photoreceptor) is desirable from the viewpoint of production cost and image quality stability. Since the single-layer type photoreceptor has a function-integrated type photosensitive layer having both charge generation ability and charge transport ability, it is difficult to obtain sensitivity as high as a stacked type photoreceptor. However, with the recent demand for higher image quality, single layer type photoconductors are required to have higher sensitivity.
In order to improve the sensitivity of the single-layer type photoreceptor, a photoreceptor using an electron transporting material having high charge transporting ability, for example, represented by the general formula (1) is known. However, in the single-layer photoconductor using the electron transport material, although high sensitivity is obtained, local charge leakage (hereinafter, also referred to as “charge leakage”) may occur when the photoconductor is charged, Due to this charge leak, a color point may occur in an image.
The charge leakage is considered to be caused by, for example, a highly hygroscopic filler (for example, a filler (calcium carbonate, kaolin, silica) of paper) adhering to the surface of the photoreceptor and injecting charges from that location. ing.
The lower the surface free energy of the photoreceptor is, the lower the surface free energy of the photoreceptor tends to be. The lower the surface free energy is, the more preferable the surface free energy is. However, if the surface free energy of the photoreceptor is reduced, toner adhesion to the photoreceptor and toner transferability to the transfer member (hereinafter, “toner adhesion and transferability”) (Also referred to as).

On the other hand, in the photoreceptor according to the present embodiment, the photosensitive layer includes a binder resin, a charge generation material, a hole transport material, and an electron transport material represented by the general formula (1) (hereinafter, “specified”). And the surface free energy on the outer peripheral surface side of the photosensitive layer is reduced to a range of 24 mN / m or more and 30 mN / m or less. This makes it difficult for the filler to adhere to the photoconductor surface (the photosensitive layer in the present embodiment). In addition, the original function of the photoconductor is secured.
Therefore, according to the photoreceptor according to the present embodiment, since the attachment of the filler to the photosensitive layer is suppressed, the occurrence of local charge leakage caused by the attachment of the filler is suppressed. As a result, the generation of color points that occur when an image is formed is suppressed.

  Further, the attachment of the filler to the photosensitive layer is liable to occur remarkably in a high humidity environment (for example, 80% RH). However, according to the photoreceptor according to the present embodiment, even in a high-humidity environment, the filler is less likely to adhere to the photosensitive layer, so that the occurrence of local charge leakage caused by the adhesion of the filler is suppressed. In addition, the occurrence of color points that occur when an image is formed is suppressed.

In the case of a single-layer type photoconductor in which the electron transporting material (specific electron transporting material) represented by the general formula (1) is contained in the photosensitive layer, the surface free energy on the outer peripheral surface side of the photosensitive layer is usually 24 mN / When it is reduced to not less than m and not more than 30 mN / m, it becomes difficult to secure the toner adhesion and transferability, which are the original functions of the photoconductor. However, according to the photoconductor of the present embodiment, the original function of the photoconductor is also ensured. Is done.
The reason for this is not clear, but is presumed to be as follows.
In the present embodiment, in order to reduce the surface free energy on the outer peripheral surface side of the photosensitive layer, the charge generating material, the hole transport material, and the specific electron transport material are provided on the outer peripheral surface side of the photosensitive layer. The photosensitive layer is prepared such that is unevenly distributed or aggregated. That is, the materials (charge generating material, hole transporting material, and specific electron transporting material) unevenly distributed or agglomerated on the surface side of the photosensitive layer contribute to the reduction of the surface free energy, and the photoreceptor itself It is thought that it has also contributed to securing the functions of

-Surface free energy of photosensitive layer-
In the photoreceptor according to the present embodiment, the surface free energy on the outer peripheral surface side of the photosensitive layer is 24 mN / m or more and 30 mN / m or less as described above, but the generation of color points that occur when an image is formed is suppressed. From the viewpoint of performing, it is preferably from 24 mN / m to 28 mN / m, and more preferably from 24 mN / m to 25 mN / m.

Surface free energy of the side of the outer peripheral surface of the photosensitive layer is measured by the following method.
First, the photosensitive layer is peeled off from the photoreceptor to be measured, and a small piece is cut out to prepare a measurement sample. Next, at a temperature of 25 ° C. and a humidity of 50% RH, using a reagent (pure water, methylene iodide, α-bromonaphthalene) having a known surface free energy of each component, a portable contact angle meter PCA- Using a Type 1 (manufactured by Kyowa Interface Co., Ltd.), the "contact angle on the outer peripheral surface side of the photosensitive layer" of each of the above reagents was measured, and the surface free energy analysis software FAMAS manufactured by the company was used to measure the sensitivity of the photosensitive layer. The surface free energy on the side of the outer peripheral surface is calculated.

-Surface roughness of photosensitive layer Sa-
In the photoreceptor according to the exemplary embodiment, the surface roughness Sa of the photosensitive layer is preferably 4.5 nm or more and 6.0 nm or less, more preferably 5 nm or less, from the viewpoint of suppressing generation of a color point generated when an image is formed. It is not less than 0.0 nm and not more than 6.0 nm, and more preferably not less than 5.5 nm and not more than 6.0 nm.
Here, the surface roughness Sa of the photosensitive layer in the present embodiment is an index of the surface roughness standardized by ISO25178, which is an international standard for three-dimensional surface texture.

When the surface roughness Sa is in the above range, the charge generation material, the hole transport material, and the specific electron transport material are likely to be appropriately unevenly or aggregated on the surface side of the photosensitive layer. , The surface free energy on the outer peripheral surface side easily falls within the above range.
As a result, the filler is less likely to adhere to the photosensitive layer, and the occurrence of local charge leakage caused by the adhesion of the filler is more easily suppressed. As a result, generation of color points that occur when an image is formed is more easily suppressed.
Further, by setting the surface roughness Sa within the above range, the photosensitive material is appropriately unevenly distributed or aggregated on the surface side of the photosensitive layer (the charge generation material, the hole transport material, and the specific electron transport material). It is thought that the original function is easily secured.
The method for controlling the surface roughness Sa of the photosensitive layer to the above range will be described later.

The surface roughness Sa of the photosensitive layer is measured by the following method.
First, the photosensitive layer is peeled off from the photoreceptor to be measured, and a small piece is cut out to prepare a measurement sample. Next, using a scanning probe microscope AFM-5200S (manufactured by Hitachi High-Tech Science Corp.) as a scanning probe microscope (SPM), a deep needle and a cantilever are used so that the amount of deflection of the cantilever is constant. By scanning horizontally (50 μm (X), 50 μm (Y)) while controlling the inter-sample distance (Z), the surface roughness Sa on the outer peripheral surface side of the photosensitive layer is measured.

Hereinafter, the electrophotographic photosensitive member according to the present embodiment will be described in detail with reference to the drawings.
FIG. 1 schematically shows a cross section of a part of an electrophotographic photosensitive member 10 according to the present embodiment.
The electrophotographic photoreceptor 10 shown in FIG. 1 includes, for example, a conductive base 3, and an undercoat layer 1 and a single-layer type photosensitive layer 2 are provided on the conductive base 3 in this order.
The undercoat layer 1 is a layer provided as needed. That is, the single-layer type photosensitive layer 2 may be provided directly on the conductive substrate 3 or may be provided via the undercoat layer 1.

  Hereinafter, each layer of the electrophotographic photosensitive member according to the exemplary embodiment will be described in detail. The description will be omitted with reference numerals omitted.

(Conductive substrate)
Examples of the conductive substrate include a metal plate containing a metal (aluminum, copper, zinc, chromium, nickel, molybdenum, vanadium, indium, gold, platinum, etc.) or an alloy (stainless steel, etc.), a metal drum, a metal belt, and the like. Is mentioned. Examples of the conductive substrate include paper, resin films, belts, and the like, on which a conductive compound (for example, a conductive polymer, indium oxide, or the like), a metal (for example, aluminum, palladium, gold, or the like) or an alloy is applied, deposited, or laminated. Are also mentioned. Here, “conductive” means that the volume resistivity is less than 10 ¹³ Ωcm.

  When the electrophotographic photosensitive member is used in a laser printer, the surface of the conductive substrate has a center line average roughness Ra of 0.04 μm or more and 0.5 μm or less for the purpose of suppressing interference fringes generated when irradiating laser light. The surface is preferably roughened below. In the case where non-interfering light is used as a light source, roughening for preventing interference fringes is not particularly necessary. However, since generation of defects due to irregularities on the surface of the conductive substrate is suppressed, it is suitable for longer life.

  Examples of the surface roughening method include wet honing performed by suspending an abrasive in water and spraying the conductive substrate, and centerless grinding in which the conductive substrate is pressed against a rotating grindstone to perform continuous grinding. And anodizing treatment.

  As a method of surface roughening, without roughening the surface of the conductive substrate, a conductive or semiconductive powder is dispersed in a resin to form a layer on the surface of the conductive substrate, A method of roughening the surface with particles dispersed in the layer may also be used.

  The surface roughening treatment by anodic oxidation is to form an oxide film on the surface of the conductive substrate by performing anodic oxidation in an electrolyte solution using a conductive substrate made of metal (for example, aluminum) as an anode. Examples of the electrolyte solution include a sulfuric acid solution and an oxalic acid solution. However, the porous anodic oxide film formed by anodic oxidation is chemically active as it is, is easily contaminated, and has a large resistance fluctuation due to the environment. Therefore, the pores of the oxide film are blocked by the volume expansion due to the hydration reaction with pressurized steam or boiling water (or a metal salt such as nickel may be added) with respect to the porous anodic oxide film. It is preferable to perform a sealing treatment for changing the material.

  The thickness of the anodic oxide film is preferably, for example, 0.3 μm or more and 15 μm or less. When the film thickness is within the above range, a barrier property against injection tends to be exhibited, and an increase in residual potential due to repeated use tends to be suppressed.

The conductive substrate may be subjected to treatment with an acidic treatment liquid or boehmite treatment.
The treatment with the acidic treatment liquid is performed, for example, as follows. First, an acidic treatment solution containing phosphoric acid, chromic acid and hydrofluoric acid is prepared. The mixing ratio of phosphoric acid, chromic acid and hydrofluoric acid in the acidic treatment liquid is, for example, in the range of 10% by mass to 11% by mass of phosphoric acid, in the range of 3% by mass to 5% by mass of chromic acid, The range is 0.5% by mass or more and 2% by mass or less, and the concentration of these acids as a whole is preferably 13.5% by mass or more and 18% by mass or less. The processing temperature is preferably, for example, 42 ° C. or more and 48 ° C. or less. The thickness of the coating is preferably 0.3 μm or more and 15 μm or less.

  The boehmite treatment is performed, for example, by immersing in pure water at 90 ° C. or more and 100 ° C. or less for 5 minutes to 60 minutes, or by contacting with heated steam at 90 ° C. to 120 ° C. for 5 minutes to 60 minutes. The thickness of the coating is preferably 0.1 μm or more and 5 μm or less. This is further anodized using an electrolyte solution having low film solubility such as adipic acid, boric acid, borate, phosphate, phthalate, maleate, benzoate, tartrate, citrate, etc. Good.

(Undercoat layer)
The undercoat layer is, for example, a layer containing inorganic particles and a binder resin.

Examples of the inorganic particles include inorganic particles having a powder resistance (volume resistivity) of 10 ² Ωcm to 10 ¹¹ Ωcm.
Among these, as the inorganic particles having the above resistance value, for example, metal oxide particles such as tin oxide particles, titanium oxide particles, zinc oxide particles, and zirconium oxide particles are preferable, and zinc oxide particles are particularly preferable.

The specific surface area of the inorganic particles determined by the BET method is preferably, for example, 10 m ² / g or more.
The volume average particle diameter of the inorganic particles is, for example, preferably from 50 nm to 2000 nm (preferably from 60 nm to 1000 nm).

  The content of the inorganic particles is, for example, preferably from 10% by mass to 80% by mass, more preferably from 40% by mass to 80% by mass, based on the binder resin.

  The inorganic particles may have been subjected to a surface treatment. Inorganic particles having different surface treatments or particles having different particle diameters may be used as a mixture of two or more kinds.

  Examples of the surface treatment agent include a silane coupling agent, a titanate coupling agent, an aluminum coupling agent, and a surfactant. Particularly, a silane coupling agent is preferable, and a silane coupling agent having an amino group is more preferable.

  Examples of the silane coupling agent having an amino group include 3-aminopropyltriethoxysilane, N-2- (aminoethyl) -3-aminopropyltrimethoxysilane, and N-2- (aminoethyl) -3-amino Examples include, but are not limited to, propylmethyldimethoxysilane, N, N-bis (2-hydroxyethyl) -3-aminopropyltriethoxysilane, and the like.

  Two or more silane coupling agents may be used as a mixture. For example, a silane coupling agent having an amino group and another silane coupling agent may be used in combination. Other silane coupling agents include, for example, vinyltrimethoxysilane, 3-methacryloxypropyl-tris (2-methoxyethoxy) silane, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 3-glycol Sidoxypropyltrimethoxysilane, vinyltriacetoxysilane, 3-mercaptopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-2- (aminoethyl) -3-aminopropyltrimethoxysilane, N-2- ( Aminoethyl) -3-aminopropylmethyldimethoxysilane, N, N-bis (2-hydroxyethyl) -3-aminopropyltriethoxysilane, 3-chloropropyltrimethoxysilane, and the like, but are not limited thereto. Not something.

  The surface treatment method using the surface treatment agent may be any known method, and may be either a dry method or a wet method.

  The treatment amount of the surface treatment agent is preferably, for example, 0.5% by mass or more and 10% by mass or less based on the inorganic particles.

  Here, the undercoat layer preferably contains an electron-accepting compound (acceptor compound) together with the inorganic particles, from the viewpoint of increasing the long-term stability of electric characteristics and the carrier blocking property.

Examples of the electron-accepting compound include quinone compounds such as chloranil and bromoanil; tetracyanoquinodimethane compounds; 2,4,7-trinitrofluorenone, 2,4,5,7-tetranitro-9-fluorenone, and the like. 2- (4-biphenyl) -5- (4-t-butylphenyl) -1,3,4-oxadiazole, 2,5-bis (4-naphthyl) -1,3,4- Oxadiazole compounds such as oxadiazole and 2,5-bis (4-diethylaminophenyl) -1,3,4oxadiazole; xanthone compounds; thiophene compounds; 3,3 ', 5,5'tetra- electron transporting substances such as diphenoquinone compounds such as t-butyl diphenoquinone;
In particular, a compound having an anthraquinone structure is preferable as the electron accepting compound. As the compound having an anthraquinone structure, for example, a hydroxyanthraquinone compound, an aminoanthraquinone compound, an aminohydroxyanthraquinone compound and the like are preferable, and specifically, for example, anthraquinone, alizarin, quinizarin, anthralphine, purpurin and the like are preferable.

  The electron-accepting compound may be contained in the undercoat layer in a state of being dispersed together with the inorganic particles, or may be contained in a state of being attached to the surface of the inorganic particles.

  Examples of a method for attaching the electron accepting compound to the surface of the inorganic particles include a dry method and a wet method.

  In the dry method, for example, while stirring inorganic particles with a mixer or the like having a large shearing force, an electron-accepting compound dissolved directly or dissolved in an organic solvent is dropped and sprayed together with dry air or nitrogen gas to form the electron-accepting compound. This is a method of attaching to the surface of inorganic particles. When the electron-accepting compound is dropped or sprayed, the temperature is preferably lower than the boiling point of the solvent. After dropping or spraying the electron-accepting compound, baking may be performed at 100 ° C. or more. The printing is not particularly limited as long as the temperature and the time at which the electrophotographic characteristics can be obtained.

  The wet method includes, for example, stirring, ultrasonic waves, a sand mill, an attritor, a ball mill, etc., while dispersing the inorganic particles in a solvent, adding an electron-accepting compound, stirring or dispersing, removing the solvent, In this method, a receptive compound is attached to the surface of inorganic particles. The solvent is removed by filtration or distillation, for example. After removing the solvent, baking may be performed at 100 ° C. or more. The printing is not particularly limited as long as the temperature and the time at which the electrophotographic characteristics can be obtained. In the wet method, the water content of the inorganic particles may be removed before the addition of the electron-accepting compound, and examples thereof include a method of removing while stirring and heating in a solvent, and a method of removing by azeotropic distillation with the solvent. No.

  The attachment of the electron-accepting compound may be performed before or after the surface treatment with the surface-treating agent is performed on the inorganic particles, or may be performed simultaneously with the attachment of the electron-accepting compound and the surface treatment with the surface-treating agent.

  The content of the electron-accepting compound is, for example, preferably from 0.01% by mass to 20% by mass, and more preferably from 0.01% by mass to 10% by mass, based on the inorganic particles.

Examples of the binder resin used for the undercoat layer include an acetal resin (for example, polyvinyl butyral), a polyvinyl alcohol resin, a polyvinyl acetal resin, a casein resin, a polyamide resin, a cellulose resin, a gelatin, a polyurethane resin, a polyester resin, and an unsaturated polyester. Resin, methacrylic resin, acrylic resin, polyvinyl chloride resin, polyvinyl acetate resin, vinyl chloride-vinyl acetate-maleic anhydride resin, silicone resin, silicone-alkyd resin, urea resin, phenol resin, phenol-formaldehyde resin, melamine resin, Known polymer compounds such as urethane resin, alkyd resin, epoxy resin, etc .; zirconium chelate compound; titanium chelate compound; aluminum chelate compound; titanium alkoxide compound ; Organic titanium compounds; known materials silane coupling agent, and the like.
Examples of the binder resin used for the undercoat layer include a charge-transporting resin having a charge-transporting group, and a conductive resin (for example, polyaniline).

Among these, as the binder resin used for the undercoat layer, a resin that is insoluble in the coating solvent of the upper layer is preferable, and in particular, urea resin, phenol resin, phenol-formaldehyde resin, melamine resin, urethane resin, and unsaturated polyester Thermosetting resin such as resin, alkyd resin, epoxy resin; at least one resin selected from the group consisting of polyamide resin, polyester resin, polyether resin, methacrylic resin, acrylic resin, polyvinyl alcohol resin and polyvinyl acetal resin; Resins obtained by reaction with a curing agent are preferred.
When two or more of these binder resins are used in combination, the mixing ratio is set as necessary.

The undercoat layer may contain various additives for improving electric characteristics, environmental stability, and image quality.
Examples of the additive include known materials such as a polycyclic fused system, an electron transporting pigment such as an azo system, a zirconium chelate compound, a titanium chelate compound, an aluminum chelate compound, a titanium alkoxide compound, an organic titanium compound, and a silane coupling agent. Can be The silane coupling agent is used for the surface treatment of the inorganic particles as described above, but may be further added to the undercoat layer as an additive.

  Examples of the silane coupling agent as an additive include vinyltrimethoxysilane, 3-methacryloxypropyl-tris (2-methoxyethoxy) silane, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, Glycidoxypropyltrimethoxysilane, vinyltriacetoxysilane, 3-mercaptopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-2- (aminoethyl) -3-aminopropyltrimethoxysilane, N-2- (Aminoethyl) -3-aminopropylmethylmethoxysilane, N, N-bis (2-hydroxyethyl) -3-aminopropyltriethoxysilane, 3-chloropropyltrimethoxysilane, and the like.

  As the zirconium chelate compound, for example, zirconium butoxide, ethyl zirconium acetoacetate, zirconium triethanolamine, acetylacetonate zirconium butoxide, ethyl zirconium butoxide acetoacetate, zirconium acetate, zirconium oxalate, zirconium lactate, zirconium phosphonate, zirconium octoate, Examples include zirconium naphthenate, zirconium laurate, zirconium stearate, zirconium isostearate, zirconium butoxide methacrylate, zirconium butoxide stearate, zirconium butoxide isostearate, and the like.

  Examples of the titanium chelate compound include tetraisopropyl titanate, tetranormal butyl titanate, butyl titanate dimer, tetra (2-ethylhexyl) titanate, titanium acetylacetonate, polytitanium acetylacetonate, titanium octylene glycolate, and titanium lactate ammonium salt , Titanium lactate, titanium lactate ethyl ester, titanium triethanol aminate, polyhydroxytitanium stearate and the like.

  Examples of the aluminum chelate compound include aluminum isopropylate, monobutoxyaluminum diisopropylate, aluminum butyrate, diethyl acetoacetate aluminum diisopropylate, and aluminum tris (ethylacetoacetate).

  These additives may be used alone or as a mixture or a polycondensate of a plurality of compounds.

The undercoat layer preferably has a Vickers hardness of 35 or more.
The surface roughness (ten-point average roughness) of the undercoat layer ranges from 1 / (4n) (n is the refractive index of the upper layer) to 1/2 of the exposure laser wavelength λ used to suppress moire images. It is good to be adjusted to.
Resin particles and the like may be added to the undercoat layer for adjusting the surface roughness. Examples of the resin particles include silicone resin particles and cross-linked polymethyl methacrylate resin particles. Further, the surface of the undercoat layer may be polished for adjusting the surface roughness. Examples of the polishing method include buffing, sand blasting, wet honing, and grinding.

  The formation of the undercoat layer is not particularly limited, and a well-known forming method is used.For example, a coating film of a coating liquid for forming an undercoat layer obtained by adding the above components to a solvent is formed, and the coating film is dried. Then, heating is performed as necessary.

As a solvent for preparing the coating liquid for forming the undercoat layer, known organic solvents, for example, alcohol solvents, aromatic hydrocarbon solvents, halogenated hydrocarbon solvents, ketone solvents, ketone alcohol solvents, ether solvents Solvents, ester solvents and the like.
Specific examples of these solvents include, for example, methanol, ethanol, n-propanol, iso-propanol, n-butanol, benzyl alcohol, methylcellosolve, ethylcellosolve, acetone, methyl ethyl ketone, cyclohexanone, methyl acetate, ethyl acetate, Usable organic solvents such as n-butyl acetate, dioxane, tetrahydrofuran, methylene chloride, chloroform, chlorobenzene, and toluene.

  Examples of the method of dispersing the inorganic particles when preparing the coating liquid for forming the undercoat layer include known methods such as a roll mill, a ball mill, a vibration ball mill, an attritor, a sand mill, a colloid mill, and a paint shaker.

  Examples of the method of applying the coating liquid for forming an undercoat layer on a conductive substrate include a blade coating method, a wire bar coating method, a spray coating method, a dip coating method, a bead coating method, an air knife coating method, and a curtain coating method. And the like.

  The thickness of the undercoat layer is set, for example, preferably in a range of 15 μm or more, more preferably in a range of 20 μm or more and 50 μm or less.

(Intermediate layer)
Although not shown, an intermediate layer may be further provided between the undercoat layer and the photosensitive layer.
The intermediate layer is, for example, a layer containing a resin. Examples of the resin used for the intermediate layer include, for example, acetal resin (for example, polyvinyl butyral), polyvinyl alcohol resin, polyvinyl acetal resin, casein resin, polyamide resin, cellulose resin, gelatin, polyurethane resin, polyester resin, methacrylic resin, acrylic resin, Polymer compounds such as polyvinyl chloride resin, polyvinyl acetate resin, vinyl chloride-vinyl acetate-maleic anhydride resin, silicone resin, silicone-alkyd resin, phenol-formaldehyde resin, and melamine resin are exemplified.
The intermediate layer may be a layer containing an organometallic compound. Examples of the organometallic compound used for the intermediate layer include organometallic compounds containing metal atoms such as zirconium, titanium, aluminum, manganese, and silicon.
The compounds used for these intermediate layers may be used alone or as a mixture or a polycondensate of a plurality of compounds.

  Among them, the intermediate layer is preferably a layer containing an organometallic compound containing a zirconium atom or a silicon atom.

The formation of the intermediate layer is not particularly limited, and a well-known forming method is used.For example, a coating film of the coating solution for forming an intermediate layer in which the above components are added to a solvent is formed, and the coating film is dried and dried. It is performed by heating according to.
As a coating method for forming the intermediate layer, a usual method such as a dip coating method, a push-up coating method, a wire bar coating method, a spray coating method, a blade coating method, a knife coating method, and a curtain coating method is used.

  The thickness of the intermediate layer is, for example, preferably set in a range of 0.1 μm or more and 3 μm or less. In addition, you may use an intermediate | middle layer as an undercoat layer.

(Single-layer type photosensitive layer)
The single-layer type photosensitive layer according to this embodiment includes a binder resin, a charge generation material, a hole transport material, an electron transport material represented by the general formula (1) (a specific electron transport material), and And other additives as required. Hereinafter, each component contained in the single-layer type photosensitive layer will be described in detail.

-Binder resin-
Although there is no particular limitation on the binder resin, for example, polycarbonate resin, polyester resin, polyarylate resin, methacrylic resin, acrylic resin, polyvinyl chloride resin, polyvinylidene chloride resin, polystyrene resin, polyvinyl acetate resin, styrene-butadiene Copolymer, vinylidene chloride-acrylonitrile copolymer, vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl acetate-maleic anhydride copolymer, silicone resin, silicone-alkyd resin, phenol-formaldehyde resin, styrene-alkyd Resins, poly-N-vinyl carbazole, polysilane, and the like are included. These binder resins may be used alone or in combination of two or more.
Among these binder resins, particularly, a polycarbonate resin is preferable from the viewpoint of suppressing the generation of a color point, and from the viewpoint of suppressing the generation of a color point and forming a photosensitive layer, for example, has a viscosity average molecular weight of 30,000 or more and 80,000. The following polycarbonate resins are more preferred.
The content of the binder resin based on the total solid content of the photosensitive layer is 35% by mass or more and 60% by mass or less, preferably 20% by mass or more and 35% by mass or less.

Here, the following one-point measurement method is used for measuring the viscosity average molecular weight of the binder resin.
First, the photosensitive layer is peeled off from the photoreceptor to be measured, and a small piece is cut out to prepare a measurement sample. Next, a binder resin is extracted from the measurement sample. 1 g of the extracted binder resin is dissolved in 100 cm ³ of methylene chloride, and its specific viscosity ηsp is measured with an Ubbelohde viscometer in a measurement environment at 25 ° C. Then, the intrinsic viscosity [η] (cm ³ / g) is obtained from the relational expression of ηsp / c = [η] +0.45 [η] ² c (where c is the concentration (g / cm ³ ), and H. Schnell The viscosity average molecular weight Mv is determined from the given equation, [η] = 1.23 × 10 ⁻⁴ Mv ^0.83 .

-Charge generation material-
Examples of the charge generation material include azo pigments such as bisazo and trisazo; condensed aromatic pigments such as dibromoanthanthrone; perylene pigments; pyrrolopyrrole pigments; phthalocyanine pigments; zinc oxide; and trigonal selenium.

  Among these, in order to cope with laser exposure in the near infrared region, it is preferable to use a metal phthalocyanine pigment or a metal-free phthalocyanine pigment as the charge generation material. Specifically, for example, hydroxygallium phthalocyanine disclosed in JP-A-5-263007 and JP-A-5-279951; chlorogallium phthalocyanine disclosed in JP-A-5-98181; Dichlorotin phthalocyanine disclosed in JP-A-140472 and JP-A-5-140473; and titanyl phthalocyanine disclosed in JP-A-4-189873 and the like are more preferred.

  On the other hand, in order to cope with laser exposure in the near ultraviolet region, as a charge generation material, condensed aromatic pigments such as dibromoanthanthrone; thioindigo pigments; porphyrazine compounds; zinc oxide; trigonal selenium; Bisazo pigments disclosed in JP-A-2004-78147 and JP-A-2005-181992 are preferred.

  That is, as the charge generation material, for example, when a light source having an exposure wavelength of 380 nm or more and 500 nm is used, an inorganic pigment is preferable, and when a light source having an exposure wavelength of 700 nm or less and 800 nm is used, metal and metal-free phthalocyanine pigments are preferable.

  Here, as the charge generation material, at least one selected from hydroxygallium phthalocyanine pigments and chlorogallium phthalocyanine pigments is preferable, and hydroxygallium phthalocyanine pigments are more preferable, from the viewpoint of increasing the sensitivity of the single-layer photoreceptor.

The hydroxygallium phthalocyanine pigment is not particularly limited, but a V-type hydroxygallium phthalocyanine pigment is preferred.
In particular, as the hydroxygallium phthalocyanine pigment, for example, a hydroxygallium phthalocyanine pigment having a maximum peak wavelength in a range of 810 nm to 839 nm in a spectral absorption spectrum in a wavelength range of 600 nm to 900 nm can obtain more excellent dispersibility. Desirable from a viewpoint. When used as a material for an electrophotographic photoreceptor, excellent dispersibility and sufficient sensitivity, chargeability and dark decay characteristics are easily obtained.

The hydroxygallium phthalocyanine pigment having the maximum peak wavelength in the range of 810 nm to 839 nm preferably has an average particle size in a specific range and a BET specific surface area in a specific range. Specifically, the average particle size is desirably 0.20 μm or less, more desirably 0.01 μm or more and 0.15 μm or less, while the BET specific surface area is desirably 45 m ² / g or more. , 50 m ² / g or more, and particularly preferably 55 m ² / g or more and 120 m ² / g or less. The average particle size is a value measured by a laser diffraction scattering type particle size distribution analyzer (LA-700, manufactured by HORIBA, Ltd.) using a volume average particle size (d50 average particle size). In addition, it is a value measured by a nitrogen displacement method using a BET type specific surface area measuring device (manufactured by Shimadzu Corporation: Flow Soap II2300).
Here, when the average particle size is larger than 0.20 μm, or when the specific surface area value is less than 45 m ² / g, the pigment particles are coarsened or an aggregate of the pigment particles tends to be formed. In addition, there is a tendency that defects such as dispersibility, sensitivity, chargeability, and dark decay characteristics tend to occur, which may easily cause image quality defects.

  The maximum particle size (maximum primary particle size) of the hydroxygallium phthalocyanine pigment is desirably 1.2 μm or less, more desirably 1.0 μm or less, and more desirably 0.3 μm or less. If the maximum particle size exceeds the above range, black spots tend to occur.

The hydroxygallium phthalocyanine pigment has an average particle size of 0.2 μm or less, a maximum particle size of 1.2 μm or less, from the viewpoint of suppressing density unevenness caused by exposing the photoreceptor to a fluorescent lamp or the like, and It is desirable that the specific surface area value be 45 m ² / g or more.

  The hydroxygallium phthalocyanine pigment has a Bragg angle (2θ ± 0.2 °) of at least 7.3 °, 16.0 °, 24.9 °, 28.0 ° in an X-ray diffraction spectrum using CuKα characteristic X-ray. It is desirable to use a V type having a diffraction peak at

On the other hand, as chlorogallium phthalocyanine pigments, for example, Bragg angles (2θ ± 0.2 °) of 7.4 °, 16.6 °, 25.5 ° and 28, which can provide excellent sensitivity as an electrophotographic photoreceptor material, can be obtained. It is desirable that the compound has a diffraction peak at 0.3 °.
The maximum peak wavelength, average particle size, maximum particle size, and specific surface area of a suitable spectral absorption spectrum of the chlorogallium phthalocyanine pigment are the same as those of the hydroxygallium phthalocyanine pigment.

  The content of the charge generating material with respect to the total solid content of the photosensitive layer is preferably from 1% by mass to 5% by mass, and more preferably from 1.2% by mass to 4.5% by mass.

−Hole transport material−
The hole transporting material is not particularly limited. For example, oxadiazole derivatives such as 2,5-bis (p-diethylaminophenyl) -1,3,4-oxadiazole; Pyrazoline derivatives such as phenyl-pyrazoline, 1- [pyridyl- (2)]-3- (p-diethylaminostyryl) -5- (p-diethylaminostyryl) pyrazoline; triphenylamine, N, N'-bis (3 Aromatic tertiary amino compounds such as 4-dimethylphenyl) biphenyl-4-amine, tri (p-methylphenyl) aminyl-4-amine and dibenzylaniline; N, N'-bis (3-methylphenyl)- Aromatic tertiary diamino compounds such as N, N'-diphenylbenzidine; 3- (4'-dimethylaminophenyl) -5,6-di- (4'-methoxy 1) 1,2,4-triazine derivatives such as -1,2,4-triazine; hydrazone derivatives such as 4-diethylaminobenzaldehyde-1,1-diphenylhydrazone; quinazoline derivatives such as 2-phenyl-4-styryl-quinazoline A benzofuran derivative such as 6-hydroxy-2,3-di (p-methoxyphenyl) benzofuran; an α-stilbene derivative such as p- (2,2-diphenylvinyl) -N, N-diphenylaniline; an enamine derivative; Carbazole derivatives such as -ethylcarbazole; poly-N-vinylcarbazole and derivatives thereof; polymers having a group composed of the above compounds in the main chain or side chain; These hole transport materials may be used alone or in combination of two or more.

  Among these, an aromatic tertiary amino compound is preferred from the viewpoint of charge mobility, and among them, a triarylamine-based hole transporting material represented by the following general formula (HT1) and a tertiary amine-based hole transporting material represented by the following general formula (HT2) Butadiene-based hole transport materials are preferred. As the triarylamine-based hole transporting material, a benzidine-based hole transporting material represented by the following general formula (HT1a) may be used.

The triarylamine-based hole transport material (HT1) will be described.
The triarylamine-based hole transport material (HT1) is a hole transport material represented by the following general formula (HT1).

In the general formula (HT1), Ar ^T1 , Ar ^T2 , and Ar ^T3 each independently represent an aryl group or —C ₆ H ₄ —C ( ^{RT 4} ) = C ( ^{RT 5} ) ( ^{RT 6} ). R ^T4 , R ^T5 , and R ^T6 each independently represent a hydrogen atom, an alkyl group, or an aryl group. R ^T5 and R ^T6 may combine to form a hydrocarbon ring structure.

In the general formula (HT1), examples of the aryl group represented by Ar ^T1 , Ar ^T2 , and Ar ^T3 include an aryl group having 6 to 15 carbon atoms (preferably 6 to 9 and more preferably 6 to 8). Can be
Specific examples of the aryl group include a phenyl group, a naphthyl group, and a fluorene group.
Among these, a phenyl group is preferable as the aryl group.

In formula (HT1), examples of the alkyl group represented by R ^T4 , R ^T5 , and R ^T6 are the same as the examples of the alkyl group represented by R ^C21 , R ^C22 , and R ^C23 in formula (HT1a) described below. Yes, the preferred range is also the same.

In the general formula (HT1), the aryl group represented by R ^T4 , R ^T5 , and R ^T6 is the same as the example of the aryl group represented by Ar ^T1 , Ar ^T2 , and Ar ^T3 , and the preferable range is also the same.

Note that in the general formula (HT1), the above substituents represented by Ar ^T1 , Ar ^T2 , and Ar ^T3 , and R ^T4 , R ^T5 , and R ^T6 also include a group having a substituent. Examples of the substituent include a halogen atom, an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, and an aryl group having 6 to 10 carbon atoms. Examples of the substituent of each of the above substituents also include a substituted amino group substituted with an alkyl group having 1 to 3 carbon atoms.

  As the triarylamine-based hole transporting material (HT1), one type may be used alone, or two or more types may be used in combination.

Here, from the viewpoint of charge mobility, among the triarylamine-based hole transporting materials represented by the general formula (HT1), in particular, “—C ₆ H ₄ —C ( ^{RT 4} ) = C ( ^{RT 5} ) ( R ^T6 ) ”is preferred. Above all, a triarylamine-based hole transporting material represented by a specific example (HT1-4) of a triarylamine-based hole transporting material (HT1) described later is preferable.

The benzidine-based hole transport material (HT1a) will be described.
The benzidine-based hole transport material (HT1a) is a hole transport material represented by the following general formula (HT1a).

In the general formula (HT1a), R ^C21 , R ^C22 , and R ^C23 each independently represent a hydrogen atom, a halogen atom, an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, or Represents an aryl group having 6 to 10 carbon atoms.

In the general formula (HT1a), examples of the halogen atom represented by R ^C21 , R ^C22 , and R ^C23 include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom. Among these, as the halogen atom, a fluorine atom and a chlorine atom are preferable, and a chlorine atom is more preferable.

In the general formula (HT1a), the alkyl group represented by R ^C21 , R ^C22 , and R ^C23 is a straight-chain alkyl group having 1 to 10 carbon atoms (preferably 1 to 6 and more preferably 1 to 4). And a branched alkyl group.
Specific examples of the linear alkyl group include methyl, ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, n- Examples include a nonyl group and an n-decyl group.
Specific examples of the branched alkyl group include an isopropyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, an isopentyl group, a neopentyl group, a tert-pentyl group, an isohexyl group, a sec-hexyl group, and a tert-hexyl group. , Isoheptyl group, sec-heptyl group, tert-heptyl group, isooctyl group, sec-octyl group, tert-octyl group, isononyl group, sec-nonyl group, tert-nonyl group, isodecyl group, sec-decyl group, tert- Decyl group and the like.
Among them, the alkyl group is preferably a lower alkyl group such as a methyl group, an ethyl group, and an isopropyl group.

In the general formula (HT1a), the alkoxy group represented by R ^C21 , R ^C22 , and R ^C23 is a linear or linear alkoxy group having 1 to 10 (preferably 1 to 6 and more preferably 1 to 4). And a branched alkoxy group.
Specific examples of the linear alkoxy group include methoxy, ethoxy, n-propoxy, n-butoxy, n-pentyloxy, n-hexyloxy, n-heptyloxy, and n-octyloxy. Group, n-nonyloxy group, n-decyloxy group and the like.
Specific examples of the branched alkoxy group include an isopropoxy group, an isobutoxy group, a sec-butoxy group, a tert-butoxy group, an isopentyloxy group, a neopentyloxy group, a tert-pentyloxy group, an isohexyloxy group, and a sec. -Hexyloxy group, tert-hexyloxy group, isoheptyloxy group, sec-heptyloxy group, tert-heptyloxy group, isooctyloxy group, sec-octyloxy group, tert-octyloxy group, isononyloxy group, Examples include a sec-nonyloxy group, a tert-nonyloxy group, an isodecyloxy group, a sec-decyloxy group, a tert-decyloxy group, and the like.
Among these, a methoxy group is preferable as the alkoxy group.

In the general formula (HT1a), examples of the aryl group represented by R ^C21 , R ^C22 , and R ^C23 include an aryl group having 6 to 10 carbon atoms (preferably 6 to 9 and more preferably 6 to 8). Can be
Specific examples of the aryl group include a phenyl group and a naphthyl group.
Among these, a phenyl group is preferable as the aryl group.

Note that in the general formula (HT1a), the substituents represented by R ^C21 , R ^C22 , and R ^C23 also include a group having a substituent. Examples of the substituent include the atoms and groups exemplified above (for example, a halogen atom, an alkyl group, an alkoxy group, and an aryl group).

  As the benzidine-based hole transport material (HT1a), one type may be used alone, or two or more types may be used in combination.

  Hereinafter, specific examples (HT1-1) to (HT1-7) of the triarylamine-based hole transporting material (HT1) and the benzidine-based hole transporting material (HT1a) are shown, but are not limited thereto. Absent.

The butadiene-based hole transport material (HT2) will be described.
The butadiene-based hole transport material (HT2) is a hole transport material represented by the following general formula (HT2).

In the general formula (HT2), R ^C11 , R ^C12 , R ^C13 , R ^C14 , R ^C15 , and R ^C16 each independently represent a hydrogen atom, a halogen atom, an alkyl group having 1 to 20 carbon atoms, and a carbon atom of 1 It represents an alkoxy group having 20 to 20 or less or an aryl group having 6 to 30 carbon atoms, and two adjacent substituents may be bonded to each other to form a hydrocarbon ring structure.
n and m each independently represent 0, 1 or 2.

In the general formula (HT2), examples of the halogen atom represented by R ^C11 , R ^C12 , R ^C13 , R ^C14 , R ^C15 , and R ^C16 include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom. Among these, as the halogen atom, a fluorine atom and a chlorine atom are preferable, and a chlorine atom is more preferable.

In Formula (HT2), the alkyl group represented by R ^C11 , R ^C12 , R ^C13 , R ^C14 , R ^C15 , and R ^C16 has 1 to 20 carbon atoms (preferably 1 to 6 and more preferably 1 to 6). 4 or less) linear or branched alkyl groups.
Specific examples of the linear alkyl group include methyl, ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, n- Nonyl group, n-decyl group, n-undecyl group, n-dodecyl group, n-tridecyl group, n-tetradecyl group, n-pentadecyl group, n-hexadecyl group, n-heptadecyl group, n-octadecyl group, n- Examples include a nonadecyl group and an n-icosyl group.
Specific examples of the branched alkyl group include an isopropyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, an isopentyl group, a neopentyl group, a tert-pentyl group, an isohexyl group, a sec-hexyl group, and a tert-hexyl group. , Isoheptyl group, sec-heptyl group, tert-heptyl group, isooctyl group, sec-octyl group, tert-octyl group, isononyl group, sec-nonyl group, tert-nonyl group, isodecyl group, sec-decyl group, tert- Decyl, isoundecyl, sec-undecyl, tert-undecyl, neoundecyl, isododecyl, sec-dodecyl, tert-dodecyl, neododecyl, isotridecyl, sec-tridecyl, tert-tridecyl, neotridec Group, isotetradecyl group, sec-tetradecyl group, tert-tetradecyl group, neotetradecyl group, 1-isobutyl-4-ethyloctyl group, isopentadecyl group, sec-pentadecyl group, tert-pentadecyl group, neopentane Decyl group, isohexadecyl group, sec-hexadecyl group, tert-hexadecyl group, neohexadecyl group, 1-methylpentadecyl group, isoheptadecyl group, sec-heptadecyl group, tert-heptadecyl group, neoheptadecyl group, isooctadecyl group, sec-octadecyl group, tert-octadecyl group, neooctadecyl group, isononadecyl group, sec-nonadecyl group, tert-nonadecyl group, neononadecyl group, 1-methyloctyl group, isoicosyl group, sec-icosyl group, te t- eicosyl group, Neoikoshiru group and the like.
Among them, the alkyl group is preferably a lower alkyl group such as a methyl group, an ethyl group, and an isopropyl group.

In Formula (HT2), the alkoxy group represented by R ^C11 , R ^C12 , R ^C13 , R ^C14 , R ^C15 , and R ^C16 has 1 to 20 carbon atoms (preferably 1 to 6 and more preferably 1 to 6). 4 or less) linear or branched alkoxy groups.
Specific examples of the linear alkoxy group include methoxy, ethoxy, n-propoxy, n-butoxy, n-pentyloxy, n-hexyloxy, n-heptyloxy, and n-octyloxy. Group, n-nonyloxy group, n-decyloxy group, n-undecyloxy group, n-dodecyloxy group, n-tridecyloxy group, n-tetradecyloxy group, n-pentadecyloxy group, n-hexadecyl Examples thereof include an oxy group, an n-heptadecyloxy group, an n-octadecyloxy group, an n-nonadecyloxy group, and an n-icosyloxy group.
Specific examples of the branched alkoxy group include an isopropoxy group, an isobutoxy group, a sec-butoxy group, a tert-butoxy group, an isopentyloxy group, a neopentyloxy group, a tert-pentyloxy group, an isohexyloxy group, and a sec. -Hexyloxy group, tert-hexyloxy group, isoheptyloxy group, sec-heptyloxy group, tert-heptyloxy group, isooctyloxy group, sec-octyloxy group, tert-octyloxy group, isononyloxy group, sec-nonyloxy group, tert-nonyloxy group, isodecyloxy group, sec-decyloxy group, tert-decyloxy group, isoundecyloxy group, sec-undecyloxy group, tert-undecyloxy group, neoundecyloxy group , Isodo Siloxy group, sec-dodecyloxy group, tert-dodecyloxy group, neododecyloxy group, isotridecyloxy group, sec-tridecyloxy group, tert-tridecyloxy group, neotridecyloxy group, isotetradecyloxy Group, sec-tetradecyloxy group, tert-tetradecyloxy group, neotetradecyloxy group, 1-isobutyl-4-ethyloctyloxy group, isopentadecyloxy group, sec-pentadecyloxy group, tert-pentadecyl Oxy group, neopentadecyloxy group, isohexadecyloxy group, sec-hexadecyloxy group, tert-hexadecyloxy group, neohexadecyloxy group, 1-methylpentadecyloxy group, isoheptadecyloxy group, sec -Heptadecyloxy Group, tert-heptadecyloxy group, neoheptadecyloxy group, isooctadecyloxy group, sec-octadecyloxy group, tert-octadecyloxy group, neooctadecyloxy group, isononadecyloxy group, sec-nonadecyloxy group, tert- Examples include a nonadecyloxy group, a neononadecyloxy group, a 1-methyloctyloxy group, an isoicosyloxy group, a sec-icosyloxy group, a tert-icosyloxy group, and a neoicosyloxy group.
Among these, a methoxy group is preferable as the alkoxy group.

In the general formula (HT2), the aryl group represented by R ^C11 , R ^C12 , R ^C13 , R ^C14 , R ^C15 , and R ^C16 has a carbon number of 6 or more and 30 or less (preferably 6 or more and 20 or less, more preferably 6 or less). And 16 or less).
Specific examples of the aryl group include a phenyl group, a naphthyl group, a phenanthryl group, and a biphenylyl group.
Among these, a phenyl group and a naphthyl group are preferable as the aryl group.

Note that in the general formula (HT2), each of the substituents represented by R ^C11 , R ^C12 , R ^C13 , R ^C14 , R ^C15 , and R ^C16 includes a group further having a substituent. Examples of the substituent include the atoms and groups exemplified above (for example, a halogen atom, an alkyl group, an alkoxy group, and an aryl group).

In the general formula (HT2), two adjacent substituents of R ^C11 , R ^C12 , R ^C13 , R ^C14 , R ^C15 , and R ^C16 (for example, R ^C11 and R ^C12 , R ^C13 and R ^C14 , R ^In the hydrocarbon ring structure in which ^C15 and R ^C16 are connected to each other, examples of the group connecting the substituents include a single bond, a 2,2'-methylene group, a 2,2'-ethylene group, and a 2,2'- Examples thereof include a vinylene group, and among these, a single bond and a 2,2′-methylene group are preferable.
Here, specific examples of the hydrocarbon ring structure include a cycloalkane structure, a cycloalkene structure, and a cycloalkanepolyene structure.

  In the general formula (HT2), n and m are preferably 1.

In the general formula (HT2), R ^C11 , R ^C12 , R ^C13 , R ^C14 , R ^C15 , and R ^{C16 each} represent a hydrogen atom or a carbon atom from the viewpoint of forming a photosensitive layer having a high hole transport ability (hole transport layer). Represents an alkyl group having 1 to 20 or less, or an alkoxy group having 1 to 20 carbon atoms, and m and n preferably represent 1 or 2, and R ^C11 , R ^C12 , R ^C13 , R ^C14 , R ^C15 , And R ^C16 represents a hydrogen atom, and m and n more preferably represent 1.
That is, the butadiene-based hole transport material (HT2) is more preferably a hole transport material (exemplified compound (HT2-3)) represented by the following structural formula (HT2a).

  Specific examples (HT2-1) to (HT2-24) of the butadiene-based hole transport material (HT2) are shown below, but the present invention is not limited thereto.

In addition, the abbreviation symbol in the said exemplary compound has the following meaning. The number before the substituent indicates the position of substitution on the benzene ring.
・ CH ₃ : methyl group ・ OCH ₃ : methoxy group

  As the butadiene-based hole transport material (HT2), one type may be used alone, or two or more types may be used in combination.

  The content of the hole transporting material is, for example, preferably from 10% by mass to 98% by mass, more preferably from 60% by mass to 95% by mass, more preferably from 70% by mass to 90% by mass based on the binder resin. It is.

−Electron transport material−
In the present embodiment, as the electron transporting material, an electron transporting material of the general formula (1) (specific electron transporting material) is applied.

In the general formula (1), R ¹¹ , R ¹² . R ¹³ . R ¹⁴ , R ¹⁵ , R ¹⁶ , and R ¹⁷ each independently represent a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group, an aryl group, or an aralkyl group. R ¹⁸ represents an alkyl group, an aryl group, or an aralkyl group.

In the general formula (1), examples of the halogen atom represented by R ^{11 to} R ¹⁷ include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

In the general formula (1), examples of the alkyl group represented by R ^{11 to} R ¹⁷ include a linear or branched alkyl group having 1 to 4 carbon atoms (preferably 1 to 3). Specific examples include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, and an isobutyl group.

In the general formula (1), examples of the alkoxy group represented by R ^{11 to} R ¹⁷ include an alkoxy group having 1 to 4 carbon atoms (preferably 1 to 3), specifically, a methoxy group, An ethoxy group, a propoxy group, a butoxy group and the like can be mentioned.

In the general formula (1), examples of the aryl group represented by R ^{11 to} R ¹⁷ include a phenyl group and a tolyl group. Among these, a phenyl group is preferable as the aryl group represented by R ^{11 to} R ¹⁷ .
In the general formula (1), examples of the aralkyl group represented by R ^{11 to} R ¹⁷ include a benzyl group, a phenethyl group, and a phenylpropyl group.

In Formula (1), examples of the alkyl group represented by R ¹⁸ include a linear alkyl group having 1 to 15 carbon atoms (preferably 3 to 12 carbon atoms), and a linear alkyl group having 3 to 15 carbon atoms (preferably). Represents a branched alkyl group having 3 to 12 carbon atoms).
Examples of the linear alkyl group having 1 to 15 carbon atoms include a methyl group, an ethyl group, an n-propyl group, an n-butyl group, an n-pentyl group, an n-hexyl group, an n-heptyl group, and n -Octyl group, n-nonyl group, n-decyl group and the like.
Examples of the branched alkyl group having 3 to 15 carbon atoms include isopropyl, isobutyl, sec-butyl, tert-butyl, isopentyl, neopentyl, tert-pentyl, isohexyl, and sec-hexyl. Group, tert-hexyl group, isoheptyl group, sec-heptyl group, tert-heptyl group, isooctyl group, sec-octyl group, tert-octyl group, isononyl group, sec-nonyl group, tert-nonyl group, isodecyl group, sec -Decyl group, tert-decyl group and the like.

In the general formula (1), examples of the aryl group represented by R ¹⁸ include a phenyl group, a methylphenyl group, and a dimethylphenyl group.

In the general formula (1), examples of the aralkyl group represented by R ¹⁸ include a group represented by —R ¹⁹ —Ar. Here, R ¹⁹ represents an alkylene group, and Ar represents an aryl group.
Examples of the alkylene group represented by R ¹⁹ include a linear or branched alkylene group having 1 to 8 carbon atoms, and include a methylene group, an ethylene group, an n-propylene group, an isopropylene group, an n-butylene group, and an isobutylene. Group, sec-butylene group, tert-butylene group, n-pentylene group, isopentylene group, neopentylene group, tert-pentylene group and the like.
Examples of the aryl group represented by Ar include a phenyl group, a methylphenyl group, a dimethylphenyl group, and the like.

In formula (1), specific examples of the aralkyl group represented by R ¹⁸ include a benzyl group, a methylbenzyl group, a dimethylbenzyl group, a phenylethyl group, a methylphenylethyl group, a phenylpropyl group, and a phenylbutyl group. .

As the electron transporting material of the general formula (1), an electron transporting material in which R ¹⁸ represents an alkyl group, an aryl group, or an aralkyl group having 3 to 12 carbon atoms from the viewpoint of increasing the sensitivity of the single-layer photoreceptor. preferable. In particular, as the electron transporting material of the formula (1), R ^{11 to} R ¹⁷ each independently represent a hydrogen atom, a halogen atom, or an alkyl group, and R ¹⁸ is an alkyl group having 3 to 12 carbon atoms; An electron transporting material showing an aryl group or an aralkyl group is preferable.

  Hereinafter, exemplary compounds of the electron transporting material represented by the general formula (1) are shown, but are not limited thereto. In addition, the following example compound numbers are described as an example compound (1-number) below. Specifically, for example, Exemplified Compound 15 is described below as “Exemplified Compound (1-15)”.

In addition, the abbreviation symbol in the said exemplary compound has the following meaning.
· Ph: phenyl or phenylene group · _p-C 2 _{H 5:} substituted ethyl group in the para position

  The content of the electron transporting material (specific electron transporting material) of the general formula (1) is, for example, 4 to the binder resin from the viewpoint of increasing the sensitivity of the photoreceptor and ensuring the function of the photoreceptor. The content is preferably from 70% by mass to 70% by mass, more preferably from 8% by mass to 50% by mass, and more preferably from 10% by mass to 30% by mass.

The electron transport material of the general formula (1) may be used alone or in combination of two or more. Further, an electron transporting material other than the electron transporting material of the general formula (1) may be used as needed, as long as the object of the present embodiment is not impaired.
The content of the electron transport material other than the electron transport material of the general formula (1) is preferably, for example, 10% by mass or less based on the entire electron transport material.

  Other electron transporting materials include, for example, p-benzoquinone, chloranyl, bromanyl, quinone-based compounds such as anthraquinone, tetracyanoquinodimethane-based compounds, xanthone-based compounds, benzophenone-based compounds, cyanovinyl-based compounds, ethylene-based compounds, and the like. And an electron transporting compound. These other electron transporting materials may be used alone or in combination of two or more, but are not limited thereto.

-Ratio of hole transport material to electron transport material of general formula (1)-
The ratio of the hole transporting material to the electron transporting material of the general formula (1) is preferably from 50/50 to 90/10 by mass ratio (hole transporting material / electron transporting material of the general formula (1)), More preferably, it is 55/45 or more and 80/20 or less.

-Other additives-
The single-layer type photosensitive layer may contain other known additives such as an antioxidant, a light stabilizer, and a heat stabilizer. Further, when the single-layer type photosensitive layer is to be the surface layer, it may contain fluororesin particles, silicone oil and the like.

<Method of Manufacturing Photoconductor (Method of Manufacturing Single-Layer Photoconductor)>
In the present embodiment, as an example of a method of manufacturing a photoconductor, a method of manufacturing a photoconductor having an undercoat layer and a photosensitive layer (single-layer type photosensitive layer) in this order on a conductive substrate will be described.
Specifically, the photoreceptor of the present embodiment is manufactured by performing an undercoat layer forming step and a photosensitive layer forming step.
The photoconductor may be manufactured without performing the undercoat layer forming step. That is, the photosensitive member may be manufactured by directly forming the photosensitive layer on the conductive substrate.

(Undercoat layer forming step)
In the undercoat layer forming step, an undercoat layer is formed using a coating liquid for forming an undercoat layer obtained by mixing a solution containing an undercoat layer component (the above-described constituent material) and a solvent. Specifically, a coating liquid for forming an undercoat layer is applied on a conductive substrate (hereinafter, also simply referred to as “substrate”), and the coating liquid (coating film) is dried to form an undercoat layer. .

  As a method of applying the coating liquid for forming an undercoat layer on a substrate, for example, known methods such as dip coating, push-up coating, wire bar coating, spray coating, blade coating, knife coating, and curtain coating are used. Is used.

  Examples of the solvent include aromatic hydrocarbons such as benzene, toluene, xylene and chlorobenzene, ketones such as acetone and 2-butanone, halogenated aliphatic hydrocarbons such as methylene chloride, chloroform and ethylene chloride, tetrahydrofuran, and ethyl ether. And ordinary organic solvents such as cyclic or linear ethers. These solvents are used alone or in combination of two or more.

  As a method of dispersing particles (for example, inorganic particles) in a coating liquid for forming an undercoat layer, a media dispersing machine such as a ball mill, a vibrating ball mill, an attritor, a sand mill, a horizontal sand mill, stirring, an ultrasonic dispersing machine, a roll mill, A medialess disperser such as a high-pressure homogenizer is used. Examples of the high-pressure homogenizer include a collision method in which the dispersion liquid is subjected to liquid-liquid collision or liquid-wall collision in a high-pressure state and dispersion, and a penetration method in which the dispersion liquid is penetrated and dispersed in a fine flow path in a high-pressure state.

(Photosensitive layer forming step)
In the photosensitive layer forming step, a solution containing the components of the photosensitive layer (charge generation material, hole transport material, specific electron transport material, binder resin, etc.), a solvent and, if necessary, other additives is mixed. The photosensitive layer is formed using the coating solution for forming a photosensitive layer thus obtained.
In this embodiment, the photosensitive layer is formed by applying a coating solution for forming a photosensitive layer on the undercoat layer and drying the coating solution (coating film).
Examples of the solvent include the same solvents as those used for the coating liquid for forming the undercoat layer.
As a method of dispersing particles (for example, a charge generating material) in a coating solution for forming a photosensitive layer and a method of applying the coating solution for forming a photosensitive layer on an undercoat layer, the particles are dispersed in a coating solution for forming an undercoat layer. And a method similar to the method of applying a coating liquid for forming an undercoat layer on a substrate.

In this embodiment, as an example of a single-layer type photosensitive layer forming process, a method of forming a photosensitive layer on an undercoat layer by a dip coating method using a dip coating device shown in FIG. 2 will be described.
First, the dip coating apparatus 200 will be described, and then a single-layer type photosensitive layer forming process performed using the dip coating apparatus 200 will be described.

The dip coating apparatus 200 shown in FIG. 2 includes a coating tank 24 that stores a coating liquid L for forming a photosensitive layer (hereinafter, also referred to as a coating liquid L), a storage tank 30 that stores the coating liquid L, and an upper part of the coating tank 24. A liquid receiving portion (coating liquid receiving portion) 28 provided on the outer peripheral surface and holding the overflowing coating liquid L, a pipe 26A connecting the liquid receiving portion 28 and the storage tank 30, a lower portion of the storage tank 30, and the coating tank 24. And a pump 32 that circulates the coating liquid L.
The pump 32 has a function of circulating the coating liquid L between the storage tank 30 and the coating tank 24 at a predetermined flow rate (circulating flow rate) to constantly overflow the coating liquid from the coating tank 24.
In addition, the dip coating apparatus 200 vents (discharges) the vapor of a solvent volatilized from the coating liquid L in the coating tank 24 and the substrate elevator 34 for dipping and lifting the substrate 22 in the coating liquid L in the coating tank 24. A ventilator, that is, a ventilator (not shown) that ventilates air containing solvent vapor, a vapor pressure controller (not shown) that controls the dew point temperature of the coating environment, and a concentration of the coating liquid L in the storage tank 30 And a stirrer (not shown) for maintaining. In addition, the base lift 34 includes the support section 20 that supports the upper portion of the base 22 and a motor 36 that moves the support section 20 up and down.

  Next, the operation of the dip coating apparatus 200 will be described by a photosensitive layer forming process performed using the dip coating apparatus 200. The photosensitive layer forming step specifically includes a dipping step, a stopping step, a lifting step, and a drying step.

(Immersion process)
In the dipping step, the base 22 on which the undercoat layer (not shown) is formed is lowered, and the base 22 is dipped in the coating liquid L. Specifically, the upper part of the base 22 is supported by the support part 20 of the base elevator 34, and the base 22 supported by the support part 20 is moved by the base elevator 34 into the coating tank 24 containing the coating liquid L. And the descent of the base 22 is stopped at a predetermined position (stop position).
The viscosity (25 ° C.) of the coating liquid L is preferably adjusted to, for example, 250 mPa · s or more and 350 mPa · s or less.

-Immersion speed of substrate 22-
In the dipping step, the substrate 22 is dipped in the coating liquid L in the coating tank 24 at a predetermined speed (immersion speed).
The immersion speed of the substrate 22 is, for example, preferably 100 mm / min to 1500 mm / min, more preferably 300 mm / min to 1000 mm / min, and even more preferably 500 mm / min to 700 mm / min.
When the immersion speed of the substrate 22 is in the above range, the disturbance of the coating liquid L occurs moderately, so that the charge generation material, the hole transport material, and the specific electron transport material are moderately unevenly distributed on the surface side of the photosensitive layer. It is likely to aggregate and be present. This makes it easier to control the surface free energy on the outer peripheral surface side of the photosensitive layer to a specific range.

(Stop process)
In the stopping step, the base 22 immersed in the coating liquid L is placed at a predetermined stopping position,
Stop for a predetermined time.
The stopping time of the base 22 in the coating liquid L is, for example, preferably 10 seconds to 20 seconds, more preferably 11 seconds to 17 seconds, and more preferably 12 seconds to 15 seconds.
When the stopping time of the substrate 22 in the coating liquid L is within the above range, when the coating liquid L is applied onto the substrate 22 (on the undercoat layer in this embodiment), the disturbance of the coating liquid L is appropriately suppressed. Is done. Thereby, the surface free energy on the outer peripheral surface side of the photosensitive layer is easily reduced.

-Circulating flow rate of coating liquid L-
In the immersion step and the stop step described above, it is preferable to immerse the base 22 while circulating the coating liquid L between the storage tank 30 and the coating tank 24 at a predetermined flow rate (circulation flow rate). In the present embodiment, the circulation flow rate is controlled by the pump 32.
The circulation flow rate of the coating liquid L is usually 1 L / min or more and 15 L / min or less from the viewpoint of improving the dispersibility of the coating liquid for forming the photosensitive layer and suppressing the sedimentation of the photosensitive layer components in the coating liquid. It is preferred that there be. However, in this embodiment, the charge generation material, the hole transport material, and the specific electron transport material are appropriately unevenly distributed or aggregated on the surface side of the photosensitive layer, and the surface free energy on the outer peripheral surface side of the photosensitive layer is reduced. In order to easily control the dispersion to a specific range, the dispersibility of the above-mentioned materials (the charge generation material, the hole transport material, and the specific electron transport material) in the coating liquid L and the pipe 26 tends to be appropriately reduced. .
For this reason, the circulation flow rate of the coating liquid L in the present embodiment is, for example, preferably 1 L / min to 13 L / min, more preferably 3 L / min to 10 L / min, and more preferably 5 L / min to 7 L / min. .

-Ventilation of solvent vapor (ventilation of air containing solvent vapor)-
In the above-described immersion step, stop step, and pulling step described later, the above-described step is usually performed while ventilating (discharging the solvent vapor) from the coating liquid L in the coating tank 24 with a ventilation device. That is, the above steps are performed while ventilating the air containing the solvent vapor.
It is generally said that the ventilation volume of the air containing the solvent vapor is preferably from 4 m ³ / min to 18 m ³ / min. However, in the present embodiment, the ventilation, preferably 10 m ³ / min or more 18m ³ / min or less, more preferably 13m ³ / min or more 18m ³ / min or less, more preferably 15 m ³ / min or more ^18m 3 / Minutes or less.
When the ventilation rate is in the above range, the vapor concentration of the solvent is reduced (the solvent is easily volatilized), and thus the drying of the coating liquid L (coating film) is promoted in the lifting step. As a result, uneven distribution or aggregation of the above-mentioned materials (charge generation material, hole transport material, and specific electron transport material) easily occurs on the surface side of the photosensitive layer, and thus the surface free energy on the outer peripheral surface side of the photosensitive layer is increased. Is easily controlled to a specific range.
In this embodiment, ventilation of the solvent vapor (ventilation of air containing the solvent vapor) is performed by a ventilation device (not shown).

−Dew point temperature of coating environment−
In the above-described immersion step, stop step, and pulling step described below, it is preferable to perform the above steps while controlling the dew point temperature of the coating environment. In this embodiment, the control of the dew point temperature of the coating environment is performed by a vapor pressure control device (not shown).
The dew point temperature of the coating environment is, for example, preferably from 6 ° C. to 10 ° C., more preferably from 7 ° C. to 10 ° C., and more preferably from 8 ° C. to 10 ° C.
When the dew point temperature of the coating environment is within the above range, dew condensation due to heat being taken off by evaporation of the solvent is suppressed, and thus, a defect due to dew condensation on the surface of the photosensitive layer hardly occurs. This makes it easier to control the surface free energy on the outer peripheral surface side of the photosensitive layer to a specific range.

-Temperature of coating liquid L-
The temperature of the coating liquid L is preferably 26.5 ° C. or more and 28.5 ° C. or less from the viewpoint of preventing the solvent in the coating liquid L from evaporating remarkably and changing the viscosity of the coating liquid L.

As described above, by controlling the immersion speed of the base 22, the stopping time of the base 22 in the coating liquid L, the circulating flow rate of the coating liquid L, the ventilation rate of air containing solvent vapor, or the dew point temperature of the coating environment. It is considered that the state of the coating liquid L (for example, a disordered state) is adjusted. Thus, considered to be easily controlled to a specific range also surface roughness Sa of the sensitive light layer co When the surface free energy of the outer peripheral surface of the photosensitive layer becomes easy to control in a specific range.

(Pulling process)
After the stopping step, a lifting step is performed. In the lifting step, the substrate 22 immersed in the coating liquid L in the stopping step is pulled up from the coating liquid L. Thereby, a coating film in which the coating liquid L is applied on the undercoat layer (not shown) is formed.
The thickness of the photosensitive layer is adjusted mainly by the speed at which the substrate 22 is pulled up from the coating liquid L, and is preferably set in the range of 5 μm to 60 μm, more preferably 10 μm to 50 μm.

(Drying process)
In the drying step, the coating liquid L adhering to the lower end portion of the substrate 22 pulled up from the coating tank 24 is wiped off, and the coating film is dried at 120 ° C. or more and 140 ° C. or less (solvent is removed by evaporation). A layer type photosensitive layer is formed.

  As described above, through the undercoat layer forming step and the photosensitive layer forming step, a single-layer type photoconductor used for an electrophotographic image forming apparatus is manufactured.

As mentioned above, although one embodiment was described about the manufacturing method of a single layer type photoreceptor, the manufacturing method of a single layer type photoreceptor is not limited to the said embodiment.
For example, in the present embodiment, a substrate elevator 34 that immerses and lifts the substrate 22 into the coating liquid L in the coating tank 24, a ventilator that ventilates (discharges) the solvent vapor volatilized from the coating liquid L in the coating tank 24, A method of manufacturing a photoconductor using a vapor pressure control device for controlling the dew point temperature of the coating environment and a stirrer for maintaining the concentration of the coating liquid L in the storage tank 30 has been described, but these devices are appropriately used. be able to. Moreover, you may use it in combination with another required apparatus.

[Image forming apparatus (and process cartridge)]
The image forming apparatus according to the present exemplary embodiment includes an electrophotographic photosensitive member, a charging unit that charges a surface of the electrophotographic photosensitive member, and an electrostatic latent image forming unit that forms an electrostatic latent image on the charged surface of the electrophotographic photosensitive member. Means, developing means for developing an electrostatic latent image formed on the surface of the electrophotographic photoreceptor with a developer containing toner to form a toner image, transfer means for transferring the toner image to the surface of the recording medium, Is provided. The electrophotographic photosensitive member according to the present embodiment is applied as the electrophotographic photosensitive member.

  The image forming apparatus according to this embodiment includes a fixing unit that fixes a toner image transferred to a surface of a recording medium; a direct transfer that directly transfers a toner image formed on a surface of an electrophotographic photosensitive member to a recording medium. -Type device; intermediate transfer in which a toner image formed on the surface of an electrophotographic photosensitive member is primarily transferred to the surface of an intermediate transfer member, and the toner image transferred on the surface of the intermediate transfer member is secondarily transferred to a surface of a recording medium. Device having a cleaning means for cleaning the surface of the electrophotographic photosensitive member after transfer of the toner image and before charging; irradiating the surface of the electrophotographic photosensitive member with static elimination light before charging after transferring the toner image. A known image forming apparatus such as a device including an electrophotographic photosensitive member heating member for raising the temperature of the electrophotographic photosensitive member and reducing the relative temperature is applied.

  In the case of an intermediate transfer type device, the transfer unit includes, for example, an intermediate transfer member on which a toner image is transferred on the surface, and a primary unit for primarily transferring the toner image formed on the surface of the electrophotographic photosensitive member to the surface of the intermediate transfer member. A configuration including a transfer unit and a secondary transfer unit that secondary-transfers the toner image transferred on the surface of the intermediate transfer body to the surface of the recording medium is applied.

  The image forming apparatus according to the present embodiment may be either a dry developing type image forming apparatus or a wet developing type (developing type using a liquid developer) image forming apparatus.

  In the image forming apparatus according to the present embodiment, for example, the portion including the electrophotographic photoreceptor may have a cartridge structure (process cartridge) that is detachable from the image forming apparatus. As the process cartridge, for example, a process cartridge provided with the electrophotographic photosensitive member according to the present embodiment is suitably used. The process cartridge may include, for example, at least one selected from the group consisting of a charging unit, an electrostatic latent image forming unit, a developing unit, and a transfer unit, in addition to the electrophotographic photosensitive member.

  Hereinafter, an example of the image forming apparatus according to the present embodiment will be described, but the present invention is not limited thereto. The main parts shown in the figure will be described, and the description of the other parts will be omitted.

FIG. 3 is a schematic configuration diagram illustrating an example of the image forming apparatus according to the present embodiment.
As shown in FIG. 3, the image forming apparatus 100 according to the present embodiment includes a process cartridge 300 having an electrophotographic photosensitive member 7, an exposure device 9 (an example of an electrostatic latent image forming unit), and a transfer device 40 (primary image forming device). Transfer device) and an intermediate transfer member 50. In the image forming apparatus 100, the exposure device 9 is disposed at a position where the electrophotographic photosensitive member 7 can be exposed through the opening of the process cartridge 300, and the transfer device 40 is connected to the electrophotographic photosensitive member via the intermediate transfer member 50. 7, and the intermediate transfer body 50 is arranged such that a part thereof is in contact with the electrophotographic photosensitive member 7. Although not shown, it also has a secondary transfer device for transferring the toner image transferred to the intermediate transfer body 50 to a recording medium (for example, paper). The intermediate transfer body 50, the transfer device 40 (primary transfer device), and the secondary transfer device (not shown) correspond to an example of a transfer unit.

  3 includes an electrophotographic photosensitive member 7, a charging device 8 (an example of a charging device), a developing device 11 (an example of a developing device), and a cleaning device 13 (an example of a cleaning device) in a housing. I support it. The cleaning device 13 has a cleaning blade (an example of a cleaning member) 131, and the cleaning blade 131 is arranged so as to contact the surface of the electrophotographic photosensitive member 7. The cleaning member is not limited to the cleaning blade 131, but may be a conductive or insulating fibrous member, which may be used alone or in combination with the cleaning blade 131.

  In FIG. 3, as an image forming apparatus, a fibrous member 132 (roll-like) for supplying the lubricant 14 to the surface of the electrophotographic photosensitive member 7 and a fibrous member 133 (flat brush-like) for assisting cleaning are provided. Are shown, but these are arranged as needed.

  Hereinafter, each configuration of the image forming apparatus according to the present embodiment will be described.

-Charging device-
As the charging device 8, for example, a contact type charger using a conductive or semiconductive charging roller, a charging brush, a charging film, a charging rubber blade, a charging tube, or the like is used. In addition, a non-contact type roller charger, a charger known per se such as a scorotron charger and a corotron charger using corona discharge, and the like are also used.

-Exposure device-
Examples of the exposure device 9 include an optical device that exposes the surface of the electrophotographic photosensitive member 7 with light such as semiconductor laser light, LED light, and liquid crystal shutter light in a predetermined image. The wavelength of the light source is within the spectral sensitivity range of the electrophotographic photosensitive member. As a wavelength of a semiconductor laser, near-infrared light having an oscillation wavelength near 780 nm is mainly used. However, the laser is not limited to this wavelength, and a laser having an oscillation wavelength of 400 nm or more and 450 nm or less as a blue laser may be used. For forming a color image, a surface emitting laser light source that can output multiple beams is also effective.

-Developing device-
As the developing device 11, for example, a general developing device that performs development by contacting or non-contacting a developer can be used. The developing device 11 is not particularly limited as long as it has the above-described functions, and is selected according to the purpose. For example, a known developing device having a function of attaching a one-component developer or a two-component developer to the electrophotographic photosensitive member 7 using a brush, a roller, or the like can be used. Among them, those using a developing roller holding a developer on the surface are preferable.

  The developer used in the developing device 11 may be a one-component developer containing only the toner or a two-component developer containing the toner and the carrier. Further, the developer may be magnetic or non-magnetic. Known developers are applied to these developers.

-Cleaning device-
As the cleaning device 13, a cleaning blade type device including a cleaning blade 131 is used.
In addition to the cleaning blade method, a fur brush cleaning method and a simultaneous development cleaning method may be employed.

-Transfer device-
As the transfer device 40, for example, a known transfer charger such as a contact type transfer charger using a belt, a roller, a film, a rubber blade, or the like, a scorotron transfer charger or a corotron transfer charger using corona discharge, or the like. No.

-Intermediate transfer body-
As the intermediate transfer member 50, a belt-like one (intermediate transfer belt) containing semiconductive polyimide, polyamideimide, polycarbonate, polyarylate, polyester, rubber, or the like is used. Further, as a form of the intermediate transfer member, a drum-shaped one may be used instead of the belt-shaped one.

FIG. 4 is a schematic configuration diagram illustrating another example of the image forming apparatus according to the present embodiment.
The image forming apparatus 120 shown in FIG. 4 is a tandem-type multicolor image forming apparatus in which four process cartridges 300 are mounted. In the image forming apparatus 120, four process cartridges 300 are arranged in parallel on the intermediate transfer member 50, and one electrophotographic photosensitive member is used for one color. Note that the image forming apparatus 120 has the same configuration as the image forming apparatus 100 except that the image forming apparatus 120 is of a tandem type.

  Hereinafter, the present embodiment will be described in detail with reference to examples, but the present embodiment is not limited to these examples. In the following description, “parts” and “%” are all based on mass unless otherwise specified.

<Example 1>
-Preparation of photoconductor (1)-
The Bragg angles (2θ ± 0.2 °) of the X-ray diffraction spectrum using Cukα characteristic X-rays as the charge generating material are at least 7.3 °, 16.0 °, 24.9 °, and 28.0 °. 4 parts by mass of a V-type hydroxygallium phthalocyanine pigment (CG1) having a diffraction peak, 58 parts by mass of a bisphenol Z polycarbonate resin (viscosity average molecular weight: 50,000: Binder 1) as a binder resin, and an electron transport material (ETM1) shown in Table 1 A mixture of 15 parts by mass, 20 parts by mass of the hole transport material (HTM1) shown in Table 1, and 250 parts by mass of tetrahydrofuran (THF) was dispersed by a nanomizer to adjust the viscosity to 300 mPa · s. A coating liquid for forming a layer was obtained.

Using the dip coating apparatus 200 shown in FIG. 2, a single-layer type photosensitive layer was formed on an aluminum substrate (hereinafter also referred to as a substrate) having a diameter of 300 mm and a length of 245 mm by the following method (photosensitive layer forming step). .
First, the coating solution for forming a photosensitive layer obtained above (hereinafter also referred to as a coating solution) is filled in a coating tank and a storage tank of a dip coating apparatus 200 shown in FIG. A single-layer type photosensitive layer was formed.

-Conditions for forming photosensitive layer-
Substrate immersion speed 500 mm / min. Stop time of substrate in coating solution 10 seconds. Pulling speed of substrate from coating solution 160 mm / min. Drying temperature and drying time of coating film 100 ° C., 15 minutes. Circulation flow rate 7 L / min., Temperature of coating liquid 27.5 ° C
・ Ventilation volume of air containing solvent vapor 18m ³ / min ・ Dew point temperature of coating environment 7 ℃

  Through the above steps, the single-layer type photoconductor (1) of Example 1 was produced.

<Examples 2 to 8, Comparative Examples 1 to 6>
Example 1 was repeated except that the composition of the coating solution for forming a photosensitive layer was changed in accordance with Tables 1 and 2, except that the amount of the charge generating material, the type and amount of the electron transport material, the type and amount of the hole transport material, and the coating conditions were changed. In the same manner as photoconductor (1), photoconductors (2) to (8) and (C1) to (C6) were produced.
In Tables 1 and 2, CG represents a charge generation material, ETM represents an electron transport material, and HTM represents a hole transport material.

[Evaluation]
(Surface free energy)
Using the obtained photosensitive member in each example, Ri by the methods already described, the surface free energy was measured on the outer peripheral surface of the sensitive light layer. The results are shown in Tables 1 and 2.

(Surface roughness Sa)
Using the photoconductor obtained in each example, the surface roughness Sa of the photosensitive layer was measured by the method described above. The results are shown in Tables 1 and 2.

(Sensitivity evaluation)
Using the photoconductor obtained in each example, the sensitivity of the photoconductor was evaluated.
The sensitivity was evaluated as half-exposure when charged to + 800V. Specifically, using an electrostatic copying paper tester (Electrostatic Analyzer EPA-8100, manufactured by Kawaguchi Electric Works, Ltd.), it is charged to +800 in an environment of 20 ° C. and 40% RH, and then the light of a tungsten lamp is used. Was converted to monochromatic light of 800 nm using a monochromator, adjusted to 1 μW / cm ² on the surface of the photoreceptor, and irradiated.
Then, the initial surface potential V0 (V) of the photoconductor surface immediately after charging, and the half-life exposure amount E _1/2 (μJ / cm ² ) at which the surface potential becomes ×× V0 (V) by light irradiation on the photoconductor surface ) Was measured.
The evaluation criteria are as follows. When the half-life exposure amount E _1/2 was 0.2 μJ / cm ² or less, it was evaluated that the sensitivity was increased. The results are shown in Tables 1 and 2.

-Evaluation criteria-
A (O): Half-exposure dose E _1/2 is 0.2 μJ / cm ² or less B (X): Half-exposure dose E _1/2 exceeds 0.2 μJ / cm ²

(Color point evaluation)
The photoconductor of each example was mounted on a remodeling machine (HL5340D manufactured by Brother), and the color point was evaluated under an environment of a temperature of 33 ° C. and 80% RH.
The color point evaluation was performed by using the remodeling machine to output 12,000 sheets of a solid white image on A4 paper, and for the image output on the 12,000th sheet, counting the number of color points generated on the image. The evaluation was based on the following criteria. The color point generated on the image is regarded as a color point generated due to local charge leakage caused by the attachment of the filler to the photosensitive layer.
In addition, it was evaluated that if the evaluation criterion is 2 or less, a problem may occur in practical use. The results are shown in Tables 1 and 2.

-Evaluation criteria-
5: 0 ≦ number of color points ≦ 3
4: 4 ≦ number of color points ≦ 7
3: 8 ≦ number of color points ≦ 10
2: 11 ≦ number of color points ≦ 14
1: 15 ≦ the number of color points ≦ 20

From the above results, it can be seen that in the present embodiment, the occurrence of color points that occur when an image is formed is suppressed as compared with Comparative Examples 2 to 6.
Examples 1 to 5, 7, and 8 in which the surface free energy on the outer peripheral surface side of the photosensitive layer is 24 mN / m or more and 30 mN / m or less, and the surface roughness Sa of the photosensitive layer is 4.5 nm or more and 6.0 nm or less. It can be seen that, compared to Example 6 in which the surface roughness Sa exceeds 6.0 nm, the occurrence of a color point that occurs when an image is formed is suppressed.
Further, the photoreceptor of the present example has good sensitivity even when the surface free energy on the outer peripheral surface side of the photosensitive layer is reduced to 24 mN / m or more and 30 mN / m or less, as compared with Comparative Example 1. It works.

The details of the abbreviations in the table are shown below.
-Charge generation material-
CG1: charge generating material represented by the following structural formula (hydroxygallium phthalocyanine pigment)

−Electron transport material−
ETM1: an electron transporting material represented by the following structural formula (exemplary compound 1-1)

ETM2: an electron transport material represented by the following structural formula

ETM3: an electron transporting material represented by the following structural formula (exemplary compound 1-15)

HTM1: hole transporting material represented by the following structural formula (4- (2,2-diphenylethenyl) -N, N-bis (4-methylphenyl) benzeneamine, exemplary compound HT1-4)

REFERENCE SIGNS LIST 1 undercoat layer, 2 photosensitive layer, 3 conductive substrate, 7 electrophotographic photosensitive member, 8 charging device, 9 exposing device, 10 electrophotographic photosensitive member, 11 developing device, 13 cleaning device, 14 lubricant, 40 transfer device, Reference Signs List 50 intermediate transfer member, 100 image forming device, 120 image forming device, 131 cleaning blade, 132 fibrous member, 133 fibrous member, 300 process cartridge support portion, 20 support portion, 22 conductive substrate, 24 coating tank, 26A, 26B piping, 28 liquid receiving part, 30 storage tank, 32 pump, 34 base lifting machine, 200 dip coating device

Claims (3)

A conductive substrate;
A single-layer type photosensitive layer provided on the conductive substrate, wherein the binder resin, the charge generation material, the hole transport material, and the electron transport material represented by the following general formula (1): hints, Ri surface free energy der less than 30mN / m 24mN / m when measuring the side of the outer peripheral surface of the photosensitive layer,
The photosensitive layer surface roughness Sa of the photosensitive layer is Ru der least 6.0nm below 4.5 nm,
An electrophotographic photosensitive member having:


(In the general formula (1), R ¹¹ , R ¹² , R ¹³ , R ¹⁴ , R ¹⁵ , R ¹⁶ , and R ¹⁷ each independently represent a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group, an aryl group, R ¹⁸ represents an alkyl group, an aryl group, or an aralkyl group.) An electrophotographic photosensitive member according to claim 1 ,
A process cartridge that is attached to and detached from the image forming apparatus. An electrophotographic photosensitive member according to claim 1 ,
Charging means for charging the surface of the electrophotographic photoreceptor,
Electrostatic latent image forming means for forming an electrostatic latent image on the surface of the charged electrophotographic photosensitive member,
Developing means for developing the electrostatic latent image formed on the surface of the electrophotographic photoreceptor to form a toner image with a developer containing toner;
Transfer means for transferring the toner image to the surface of a recording medium,
An image forming apparatus comprising: