JP2019061145A - Electrophotographic photoreceptor, process cartridge, and image forming apparatus - Google Patents

Abstract

To provide an electrophotographic photoreceptor that prevents a variation in image density occurring when images are repeatedly formed.SOLUTION: An electrophotographic photoreceptor comprises: a conductive substrate; an undercoat layer that is provided on the conductive substrate, the undercoat layer containing a binder resin, metal oxide particles, and an electron-accepting compound, wherein when immersed in a mixed solvent containing butyl acetate and methyl isobutyl ketone at a mass ratio of 7:3, the amount of elusion of the electron-accepting compound per 1 g of the undercoat layer is 1×10g or more and 1×10g or less; and a photosensitive layer that is provided on the undercoat layer.SELECTED DRAWING: Figure 1

Description

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

  Electrophotographic image forming apparatuses are used in image forming apparatuses such as copying machines and laser beam printers. As an electrophotographic photosensitive member used in an image forming apparatus, an organic photosensitive member using an organic photoconductive material is in the mainstream. In the case of producing an organic photoreceptor, for example, an undercoat layer (sometimes referred to as an intermediate layer) is often formed on a conductive substrate such as aluminum, and then a photosensitive layer is often formed.

For example, Patent Document 1 describes “an undercoat layer containing zinc oxide particles surface-treated with at least one coupling agent, a reactive acceptor substance having an anthraquinone skeleton, and a binding resin, The amount of the reactive acceptor substance to be extracted when dissolved in 10 ml of the organic solvent capable of dissolving the reactive acceptor substance per 100 mg of the undercoat layer is 1 × 10 ⁻⁵ mol / L or more and 1 × 10 ⁻⁴ mol / L An electrophotographic photosensitive member having an undercoat layer in the following range is disclosed.

Patent No. 5982769

  When an electrophotographic photosensitive member having an undercoat layer containing a binder resin, metal oxide particles, and an electron accepting compound is used to form an image repeatedly, fluctuations in image density may occur.

Therefore, an object of the present invention is to provide an electrophotographic photosensitive member having an undercoat layer containing a binder resin, metal oxide particles, and an electron accepting compound, wherein a mixed solvent of butyl acetate and methyl isobutyl ketone in a mass ratio of 7: 3 Electrophotographic sensitization which suppresses variations in image density which occur when images are repeatedly formed, as compared to the case where the amount of the electron accepting compound eluted per 1 g of the undercoat layer exceeds 1 × 10 ⁻⁵ g when immersed in It is to provide the body.

  The above-mentioned subject is solved by the following means.

The invention according to claim 1 is
A conductive substrate,
The undercoating layer provided on the conductive substrate, which contains a binder resin, metal oxide particles, and an electron accepting compound, and is immersed in a mixed solvent of butyl acetate and methyl isobutyl ketone at a mass ratio of 7: 3. An undercoat layer having an elution amount of 1 × 10 ⁻⁷ g to 1 × 10 ⁻⁵ g per 1 g of the undercoat layer;
A photosensitive layer provided on the undercoat layer;
An electrophotographic photosensitive member having

The invention according to claim 2 is
The electrophotographic photosensitive member according to claim 1, wherein the electron accepting compound is an electron accepting compound having a reactive group.

The invention according to claim 3 is
The electrophotographic photosensitive member according to claim 2, wherein the electron accepting compound having a reactive group is an electron accepting compound having an OH group.

The invention according to claim 4 is
The electrophotographic photosensitive member according to claim 3, wherein the electron accepting compound having an OH group is an electron accepting compound represented by the following general formula (1A).

(In general formula (1A), R ¹¹ represents a hydrogen atom, an alkoxy group having 1 to 10 carbon atoms, or an aryl group having 6 to 30 carbon atoms, and n represents an integer of 1 to 7). )

The invention according to claim 5 is
The electrophotographic photosensitive member according to any one of claims 1 to 4, wherein the metal oxide particles are metal oxide particles surface-treated with a coupling agent having an amino group.

The invention according to claim 6 is
The electrophotographic photosensitive member according to claim 5, wherein the metal oxide particles surface-treated with the coupling agent are zinc oxide particles.

The invention according to claim 7 is
The electrophotographic photosensitive member according to any one of claims 1 to 6, wherein the binder resin is a crosslinked resin.

The invention according to claim 8 is
The electrophotographic photosensitive member according to claim 7, wherein the crosslinked resin is a polyurethane resin.

The invention according to claim 9 is
An electrophotographic photosensitive member according to any one of claims 1 to 8.
Process cartridge to be attached to and removed from the image forming apparatus.

The invention according to claim 10 is
An electrophotographic photosensitive member according to any one of claims 1 to 8.
Charging means for charging the surface of the electrophotographic photosensitive member;
Electrostatic latent image forming means for forming an electrostatic latent image on the surface of the electrophotographic photosensitive member charged;
Developing means for developing an electrostatic latent image formed on the surface of the electrophotographic photosensitive member with a developer containing toner to form a toner image;
A transfer unit that transfers the toner image to the surface of a recording medium;
An image forming apparatus comprising:

According to the invention of claim 1, in the electrophotographic photosensitive member having the undercoating layer containing the binder resin, the metal oxide particles, and the electron accepting compound, the mass ratio of butyl acetate and methyl isobutyl ketone is 7: 3. Electrons that suppress variations in image density that occur when images are repeatedly formed when immersed in a mixed solvent, as compared with the case where the elution amount of the electron accepting compound per 1 g of the undercoat layer exceeds 1 × 10 ⁻⁵ g A photosensitive member is provided.
According to the invention as set forth in claim 2, 3 or 4, the image is repeated more than in the case where the electron accepting compound is a non-reactive electron accepting compound (electron accepting compound having no reactive group). An electrophotographic photosensitive member is provided which suppresses the fluctuation of image density which occurs upon formation.
According to the invention according to claim 5 or 6, as compared with the case where the metal oxide particles are metal oxide particles surface-treated with a surfactant, the fluctuation of the image density which occurs when the image is repeatedly formed is suppressed An electrophotographic photosensitive member is provided.
According to the invention as set forth in claim 7 or 8, an electrophotographic photosensitive member is provided which suppresses the fluctuation of the image density as compared with the case where the binder resin is a non-crosslinked resin.
According to the invention as set forth in claim 9 or 10, in the electrophotographic photosensitive member having a binder resin, metal oxide particles and an undercoat layer containing an electron accepting compound, the mass ratio of butyl acetate and methyl isobutyl ketone 7 When the image is repeatedly formed, as compared with the case of including an electrophotographic photosensitive member in which the elution amount of the electron accepting compound per 1 g of the undercoat layer is more than 1 × 10 ⁻⁵ g when immersed in a mixed solvent of 1: 3. A process cartridge, or an image forming apparatus, is provided that suppresses variations in image density that occur.

FIG. 2 is a schematic partial cross-sectional view showing an example of the layer configuration of the electrophotographic photosensitive member according to the present embodiment. FIG. 6 is a schematic partial cross-sectional view showing another example of the layer configuration of the electrophotographic photosensitive member according to the present embodiment. FIG. 6 is a schematic partial cross-sectional view showing another example of the layer configuration of the electrophotographic photosensitive member according to the present embodiment. FIG. 1 is a schematic configuration view showing an image forming apparatus according to the present embodiment. FIG. 6 is a schematic configuration view showing an image forming apparatus according to another embodiment of the present invention.

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

[Electrophotographic photosensitive member]
The electrophotographic photosensitive member according to the present embodiment (hereinafter also referred to as “photosensitive member”) comprises a conductive substrate, an undercoat layer provided on the conductive substrate, and a photosensitive layer provided on the undercoat layer. And. The undercoat layer contains a binder resin, metal oxide particles, and an electron accepting compound, and is immersed in a mixed solvent of butyl acetate and methyl isobutyl ketone in a mass ratio of 7: 3 per gram of the undercoat layer. The elution amount of the electron accepting compound (hereinafter, also simply referred to as “elution amount of the electron accepting compound”) is 1 × 10 ⁻⁷ g or more and 1 × 10 ⁵ g or less.

  Here, when a photoreceptor having an undercoat layer containing a binder resin, metal oxide particles, and an electron accepting compound is used to form an image repeatedly, fluctuations in image density may occur. This is considered to be due to the fact that, when image formation is repeated and charging and exposure are repeated, the electron accepting compound captures the charge, and the residual potential of the photoreceptor increases.

  On the other hand, the photoconductor according to the present embodiment, with the above-described configuration, suppresses the fluctuation of the image density that occurs when an image is repeatedly formed. The reason is guessed as follows.

  When the elution amount of the electron accepting compound is in the above range, it means that a large amount of the electron accepting compound immobilized by reaction with other components is present in the undercoat layer. And, when the charge accepting compound is immobilized, the charge capturing ability is reduced. This is because the hydroxyl group which is the end group in the electron accepting compound and the other components of the undercoating layer remain in the undercoating layer without immobilizing reaction, and the hydroxy group in the remaining electron accepting substance is This is because it is considered to generate charge traps. Therefore, even if the image is repeatedly formed, the electron accepting compound in the undercoat layer hardly captures charges, and the increase in residual potential of the photoreceptor is suppressed.

  From the above, it is presumed that the photosensitive member according to the present embodiment suppresses the fluctuation of the image density which occurs when the image is repeatedly formed.

On the other hand, if the elution amount of the electron accepting compound is less than 1 × 10 ⁻⁷ g and the electron accepting compound having high charge capturing ability (the electron accepting compound which is not immobilized) is excessively reduced, in the initial stage of image formation. The target image density may not be obtained. Although the reason is not clear, it is considered that the exposure potential for forming the electrostatic latent image becomes excessively low.
Therefore, in the photosensitive member according to the present embodiment, the target image density can be easily obtained in the initial stage of image formation by setting the elution amount of the electron accepting compound to 1 × 10 ⁻⁷ g or more.

  Further, in the photosensitive member according to the present embodiment, by setting the elution amount of the electron accepting compound in the above range, electrons to the photosensitive layer (for example, the charge generation layer or the single layer photosensitive layer) of the upper layer of the undercoat layer are obtained. Contamination of the acceptor compound is also suppressed. As a result, the deterioration of the electrical characteristics is also suppressed.

In the photosensitive member according to the present embodiment, the upper limit of the elution amount of the electron accepting compound is preferably 1.0 × 10 ⁻⁵ g or less, and 5.0 × 10 ⁻⁶ g or less from the viewpoint of suppressing fluctuation of the image density. Is more preferred.
On the other hand, the lower limit of the elution amount of the electron accepting compound is preferably 1.0 × 10 ⁻⁶ g or more, and 5.0 × 10 ⁻⁶ or more from the viewpoint that the target image density can be easily obtained in the initial stage of image formation. g or more is more preferable.

The elution amount of the electron accepting compound is measured by the following method.
A part of the undercoat layer is collected from the photoreceptor and used as a measurement sample. The method of collecting a part of the undercoat layer from the photosensitive member is not particularly limited, and for example, there are the following methods. First, the charge transport layer and the charge generation layer are peeled off by polishing, and then the undercoat layer formed on the conductive substrate is fixed, and the entire conductive substrate is bent from the opposite end which is a free end. Thereby, the undercoat layer and the conductive substrate are peeled off, and a part of the undercoat layer is collected from the photoreceptor.
Meanwhile, a mixed solvent of mass ratio (BA: MIBK) 7: 3 of butyl acetate and methyl isobutyl ketone (MIBK) is prepared. The liquid temperature of the mixed solvent is 22 ° C. (room temperature).
Next, after immersing the measurement sample in the mixed solvent, the mixed solvent and the measurement sample are separated. The immersion time is 5 minutes.
Next, the absorption spectrum (UV-VIS) of an ultraviolet and visible light area | region is measured by Hitachi Ltd. make, ultraviolet visible spectrophotometer U-4100 form using the obtained mixed solvent. Then, the elution amount of the electron-accepting substance eluted in the mixed solvent is calculated from calibration curves prepared by dissolving various electron-accepting substances in the mixed solvent at various concentrations. Thus, the elution amount of the electron accepting compound per 1 g of the undercoat layer is calculated.

The control method for setting the elution amount of the electron accepting compound in the above range is, for example, an aspect using an electron accepting compound having a reactive group (in particular, a hydroxyl group) as the electron accepting compound, and a cup as a metal oxide particle. Embodiment using metal oxide particles (in particular, zinc oxide particles) surface-treated with a ring agent (in particular, a silane coupling agent having an amino group), and a crosslinked resin (in particular, an isocyanate compound) as a binder resin And the like, and a method of increasing the drying temperature at the time of forming the undercoat layer, and the like.
By this method, in the undercoat layer, the electron accepting compound, the metal oxide particles, and the binder resin are reacted, and the electron accepting compound is easily immobilized in the undercoat layer. As a result, the elution amount of the electron accepting compound can be easily controlled within the above range.

Hereinafter, the electrophotographic photosensitive member according to the present embodiment will be described in detail with reference to the drawings.
FIG. 1 is a schematic cross-sectional view showing an example of the electrophotographic photosensitive member according to the present embodiment. FIG. 2 and FIG. 3 are each a schematic cross-sectional view showing another example of the electrophotographic photosensitive member according to the present embodiment.

  The electrophotographic photoreceptor 7A shown in FIG. 1 is a so-called function separation type photoreceptor (or laminated type photoreceptor), the undercoat layer 1 is provided on the conductive substrate 4, and the charge generation layer 2, charge is formed thereon. It has a structure in which the transport layer 3 and the protective layer 5 are sequentially formed. In the electrophotographic photoreceptor 7A, the charge generation layer 2 and the charge transport layer 3 constitute a photosensitive layer.

Like the electrophotographic photoreceptor 7A shown in FIG. 1, the electrophotographic photoreceptor 7B shown in FIG. 2 is a functionally separated photoreceptor in which the functions are separated into the charge generation layer 2 and the charge transport layer 3.
In the electrophotographic photoreceptor 7B shown in FIG. 2, the undercoat layer 1 is provided on the conductive substrate 4, and the charge transport layer 3, the charge generation layer 2, and the protective layer 5 are sequentially formed thereon. The In the electrophotographic photoreceptor 7B, the charge transport layer 3 and the charge generation layer 2 constitute a photosensitive layer.

  The electrophotographic photoreceptor 7C shown in FIG. 3 contains the charge generation material and the charge transport material in the same layer (single-layer type photosensitive layer 6). The electrophotographic photosensitive member 7C shown in FIG. 3 has a structure in which the undercoat layer 1 is provided on the conductive substrate 4 and the single layer type photosensitive layer 6 is formed thereon.

  Hereinafter, each element of the electrophotographic photosensitive member 7A shown in FIG. 1 will be described as a representative example. In addition, the code | symbol is abbreviate | omitted and demonstrated.

(Conductive substrate)
As the conductive substrate, for example, a metal plate containing metal (aluminum, copper, zinc, chromium, nickel, molybdenum, vanadium, indium, gold, platinum etc.) or alloy (stainless steel etc.), metal drum, metal belt etc. Can be mentioned. In addition, as the conductive substrate, for example, paper coated with a conductive compound (eg, conductive polymer, indium oxide etc.), metal (eg, aluminum, palladium, gold etc.) or alloy, vapor deposition or lamination, resin film, belt etc. Can also be mentioned. Here, “conductive” means that the volume resistivity is less than 10 ¹³ Ωcm.

  When the electrophotographic photosensitive member is used for a laser printer, the surface of the conductive substrate has a center line average roughness Ra of not less than 0.04 μm and not more than 0.5 μm for the purpose of suppressing interference fringes generated when irradiating a laser beam. It is preferable to be roughened below. In the case where non-interference light is used as a light source, roughening for preventing interference fringes is not particularly required, but it is more suitable for prolonging the life to suppress generation of defects due to unevenness on the surface of the conductive substrate.

  As a method of surface roughening, for example, wet honing performed by suspending an abrasive in water and spraying it onto a conductive substrate, centerless grinding in which a conductive substrate is pressed against a rotating grindstone and grinding is continuously performed , Anodizing treatment, and the like.

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

  In the surface roughening treatment by anodizing, an oxide film is formed on the surface of a conductive substrate by anodizing in a electrolytic solution using a metal (for example, aluminum) conductive substrate 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, easily polluted, and has a large resistance fluctuation due to the environment. Therefore, for the porous anodic oxide film, the fine pores of the oxide film are blocked by volume expansion due to hydration reaction with pressurized steam or boiling water (a metal salt such as nickel may be added), and more stable hydrated oxidation It is preferable to carry out the sealing process which changes into a thing.

  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 in the above range, the barrier property against injection tends to be exhibited, and the increase in residual potential due to repeated use tends to be suppressed.

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

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

(Sublayer)
The undercoat layer contains a binder resin, metal oxide particles, and an electron accepting compound.

The binder resin used for the undercoat layer will be described.
Examples of the binder resin used for the undercoat layer include acetal resin (for example, polyvinyl butyral etc.), polyvinyl alcohol resin, polyvinyl acetal resin, casein resin, polyamide resin, cellulose resin, gelatin, polyurethane resin, polyester resin, 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 also include a charge transporting resin having a charge transporting group, a conductive resin (for example, polyaniline and the like), and the like.

Among these, as the binder resin used in the undercoat layer, resins insoluble in the coating solvent of the upper layer are preferable, and in particular, urea resin, phenol resin, phenol-formaldehyde resin, melamine resin, urethane resin, unsaturated polyester Thermosetting resin such as resin, alkyd resin, epoxy resin; and 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 Crosslinked resins obtained by reaction with a crosslinking agent are preferred.
The crosslinking agent and the electron accepting compound having a reactive group react with each other, the electron accepting compound is easily immobilized, and the fluctuation of the image density generated when the image is repeatedly formed is easily suppressed.

  Specifically, in particular, when the electron accepting compound has an OH group, a resin having an OH group at a terminal group or an OH group as a resin raw material (a group consisting of polyvinyl acetal resin, polyvinyl resin, casein, phenol resin, etc. A cross-linked resin obtained by the reaction of at least one selected from: and a curing agent having at least one reactive group that reacts with an OH group (at least one selected from the group consisting of isocyanate compounds, phenolic compounds, melanin etc.) Is preferred.

  When two or more binder resins are used in combination, the mixing ratio is set as necessary.

Next, metal oxide particles will be described.
Examples of metal oxide particles include metal oxide particles having a powder resistance (volume resistivity) of 10 ² Ωcm or more and 10 ¹¹ Ωcm or less.
Among these, as a metal oxide particle, a tin oxide particle, a titanium oxide particle, a zinc oxide particle, a zirconium oxide particle etc. are mentioned, for example. Among these, as the metal oxide particles, at least one selected from the group consisting of zinc oxide particles and titanium oxide particles is preferable, and zinc oxide particles are particularly preferable.
The metal oxide particles may be used singly or in combination of two or more.

  The average primary particle diameter of the metal oxide particles is preferably 500 nm or less, specifically 20 nm to 200 nm is preferable, 30 nm to 150 nm is more preferable, and 30 nm to 100 nm is further preferable.

  One hundred primary particles of metal oxide particles are observed with a scanning electron microscope (SEM) device. The longest diameter and the shortest diameter for each particle are measured by image analysis of primary particles in the observed SEM image, and the equivalent spherical diameter is measured from this intermediate value. Let 50% diameter (D50p) in the accumulation frequency of the number-based basis of the obtained sphere equivalent diameter be the average primary particle diameter of metal oxide particles.

The specific surface area of the metal oxide particles according to the BET method is, for example, preferably 10 m ² / g or more.

  The content of the metal oxide particles is, for example, preferably 10% by mass to 80% by mass, and more preferably 40% by mass to 80% by mass, with respect to the binder resin.

The metal oxide particles may be subjected to surface treatment.
As a surface treating agent, a silane coupling agent, a titanate coupling agent, an aluminum coupling agent, surfactant etc. are mentioned, for example. In particular, silane coupling agents are preferred.

The residue of the coupling agent reacts with the electron accepting compound having a reactive group to facilitate immobilization of the electron accepting compound, and fluctuations in image density that occur when repetitive images are formed are likely to be suppressed.
Specifically, in particular, when the electron accepting compound has an OH group, a coupling agent having an amino group is preferable, and a silane coupling agent having an amino group is more preferable.

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

  You may use a silane coupling agent in mixture of 2 or more types. For example, a silane coupling agent having an amino group may be used in combination with another silane coupling agent. Other silane coupling agents include, for example, vinyltrimethoxysilane, 3-methacryloxypropyl-tris (2-methoxyethoxy) silane, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 3-glylic Cidoxypropyltrimethoxysilane, vinyltriacetoxysilane, 3-mercaptopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-2- (aminoethyl) -3-aminopropyltrimethoxysilane, N-2- ( Aminoethyl) -3-aminopropylmethyldimethoxysilane, N, N-bis (2-hydroxyethyl) -3-aminopropyltriethoxysilane, 3-chloropropyltrimethoxysilane, etc., but is limited thereto It is not a thing.

  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 processing amount of the surface treatment agent is preferably, for example, 0.5% by mass or more and 10% by mass or less with respect to the metal oxide particles.

Next, the electron accepting compound will be described.
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) -1,3,4 oxadiazole; xanthone compounds; thiophene compounds; 3,3 ', 5,5'tetra- Examples include diphenoquinone compounds such as t-butyl diphenoquinone; electron transporting substances such as, and the like.

Among these, as the electron accepting compound, anthraquinone electron accepting compounds are preferable.
The anthraquinone electron accepting compound is an electron accepting compound having an anthraquinone skeleton. The anthraquinone-based electron accepting compound may be a compound having a substituent (for example, a hydroxyl group, an amino group or the like) in the anthraquinone skeleton.

  On the other hand, the electron accepting compound is preferably an electron accepting compound having a reactive group (in particular, an OH group). The crosslinker of the binder resin and the residue of the coupling agent react with the electron accepting compound having a reactive group to facilitate the immobilization of the electron accepting compound, and the image density generated when the image is repeatedly formed Fluctuations are easily suppressed.

  Therefore, the electron accepting compound is preferably an anthraquinone electron accepting compound having a reactive group (in particular, an OH group). The anthraquinone-based electron accepting compound having a reactive group (in particular, an OH group) is a compound in which at least one of the hydrogen atoms of the aromatic ring in the anthraquinone skeleton is substituted with a reactive group (in particular, an OH group).

  Specifically, the anthraquinone electron accepting compound having a reactive group (in particular, an OH group) is preferably a compound represented by the following general formula (1), a compound represented by the following general formula (2), etc. The compound represented by the following general formula (1A) is more preferable.

In General Formula (1), n1 and n2 each independently represent an integer of 0 or more and 4 or less. However, at least one of n1 and n2 independently represents an integer of 1 or more and 4 or less (that is, n1 and n2 do not simultaneously represent 0). m1 and m2 each independently represent an integer of 0 or 1. Each of R ¹ and R ² independently represents an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, or an aryl group having 6 to 30 carbon atoms.

In General Formula (2), n1, n2, n3, and n4 each independently represent an integer of 0 or more and 3 or less. m1 and m2 each independently represent an integer of 0 or 1. At least one of n1 and n2 each independently represents an integer of 1 or more and 3 or less (that is, n1 and n2 do not simultaneously represent 0). At least one of n3 and n4 independently represents an integer of 1 or more and 3 or less (that is, n3 and n4 do not simultaneously represent 0). r represents an integer of 2 or more and 10 or less. Each of R ¹ and R ² independently represents an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, or an aryl group having 6 to 30 carbon atoms.

Here, in the general formulas (1) and (2), the alkyl group having 1 to 10 carbon atoms represented by R ¹ and R ² may be linear or branched, for example, a methyl group, Ethyl group, propyl group, isopropyl group and the like can be mentioned. The alkyl group having 1 to 10 carbon atoms is preferably an alkyl group having 1 to 8 carbon atoms, more preferably an alkyl group having 1 to 6 carbon atoms.
The alkoxy group having 1 to 10 carbon atoms represented by R ¹ and R ² may be linear or branched, and examples thereof include a methoxy group, an ethoxy group, a propoxy group, an isopropoxy group, a butoxy group and an octoxy group. And the like. The alkoxy group having 1 to 10 carbon atoms is preferably an alkoxy group having 1 to 8 carbon atoms, and more preferably an alkoxy group having 1 to 6 carbon atoms.
In the general formulas (1) and (2), examples of the aryl group having 6 to 30 carbon atoms represented by R ¹ and R ² include a phenyl group; a group in which one hydrogen atom deviates from alkylbenzene (benzyl group, tolyl Group, xylyl group, methicyl group etc.); naphthyl group; a group in which one hydrogen atom is removed from an alkyl group-substituted naphthalene.
The aryl group may have a substituent. Examples of the substituent with which the aryl group is substituted include alkyl groups having 1 to 6 carbon atoms (such as methyl, ethyl and propyl), aryl groups having 6 to 30 carbon atoms, and 1 to 10 carbon atoms. The following alkoxy groups, halogen atoms (fluorine atom, chlorine atom, bromine atom etc.), nitro group, amido group, hydroxy group, ester group, ether group, aldehyde group may be mentioned.

In General Formula (1A), R ¹¹ represents a hydrogen atom, an alkoxy group having 1 to 10 carbon atoms, or an aryl group having 6 to 30 carbon atoms. n represents an integer of 1 or more and 7 or less.

In the general formula (1A), the alkoxy group having 1 to 10 carbon atoms represented by R ¹¹ is the same as the alkoxy group having 1 to 10 carbon atoms represented by R ¹ and R ² in the general formula (1) The preferred range is also the same.
In the general formula (1A), the aryl group having 6 to 30 carbon atoms represented by R ¹¹ is the same as the aryl group having 6 to 30 carbon atoms represented by R ¹ and R ² in the general formula (1) The preferred range is also the same.
In the general formula (1A), n is preferably an integer of 1 or more and 7 or less, more preferably an integer of 2 or more and 5 or less.

Here, specifics of the electron accepting compound are shown below. However, it is not limited to these.
In addition, in the specific example of a following compound, it is called an "exemplary compound", for example, if it is a compound of the following (1-1), it will be called an "exemplified compound (1-1)."
In the following exemplified compounds, “Me” is a methyl group, “Et” is an ethyl group, “Bu” is an n-butyl group, “C ₅ H ₁₁ ” is an n-pentyl group, and “C ₆ H ₁₃ ” is n -Hexyl group, "C ₇ H ₁₅ " is n-heptyl group, "C ₈ H ₁₇ " is n-octyl group, "C ₉ H ₁₉ " is n-nonyl group, "C ₁₀ H ₂₁ " is n-decyl Represents a group.

  The content of the electron accepting compound is, for example, preferably 0.01% by mass or more and 20% by mass or less, and preferably 0.01% by mass or more and 10% by mass or less, based on the metal oxide particles.

The undercoat layer may contain various additives to improve the electrical properties, the environmental stability, and the image quality.
Examples of the additive include known materials such as polycyclic condensation type and electron transporting pigments such as azo type, zirconium chelate compounds, titanium chelate compounds, aluminum chelate compounds, titanium alkoxide compounds, organic titanium compounds, and silane coupling agents. Be The silane coupling agent is used for the surface treatment of the metal oxide particles as described above, but may be further added to the undercoat layer as an additive.

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

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

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

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

  These additives may be used alone or as a mixture or 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 is from 1 / (4 n) (n is the refractive index of the upper layer) to 1/2 of the exposure laser wavelength λ used for moire image suppression It is good to be adjusted.
Resin particles and the like may be added to the undercoat layer to adjust the surface roughness. Examples of the resin particles include silicone resin particles and crosslinked polymethyl methacrylate resin particles. In addition, the surface of the undercoat layer may be polished to adjust the surface roughness. The polishing method may, for example, be buffing, sand blasting, wet honing or grinding.

  The formation of the undercoat layer is not particularly limited as long as it is adjusted to satisfy the reflectance RL by the operation as described above, but, for example, a coating film of the undercoat layer forming coating solution obtained by adding the above components to a solvent is formed And the coating is dried and heated if necessary.

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

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

  As a method of applying the coating liquid for undercoat layer formation on a conductive substrate, for example, blade coating method, wire bar coating method, spray coating method, dip coating method, bead coating method, air knife coating method, curtain coating method Etc. can be mentioned.

  The thickness of the undercoat layer is, for example, preferably in the range of 5 μm or more, and more preferably 10 μm to 50 μm.

(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 acetal resin (eg, polyvinyl butyral etc.), 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, melamine resin and the like can be mentioned.
The intermediate layer may be a layer containing an organometallic compound. Examples of the organic metal compound used for the intermediate layer include organic metal compounds containing metal atoms such as zirconium, titanium, aluminum, manganese and silicon.
The compounds used in these intermediate layers may be used alone or as a mixture or polycondensate of a plurality of compounds.

  Among these, the intermediate layer is preferably a layer containing an organic metal compound containing a zirconium atom or a silicon atom.

The formation of the intermediate layer is not particularly limited, and a known formation method is used. For example, a coating film of the coating liquid for forming an intermediate layer in which the above components are added to a solvent is formed, and the coating film is dried. It does 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 or a curtain coating method is used.

  The film thickness of the intermediate layer is preferably set, for example, in the range of 0.1 μm to 3 μm. The intermediate layer may be used as a subbing layer.

(Charge generation layer)
The charge generation layer is, for example, a layer containing a charge generation material and a binder resin. The charge generation layer may be a vapor deposition layer of a charge generation material. The deposition layer of the charge generation material is suitable when using an incoherent light source such as an LED (Light Emitting Diode) or an organic EL (Electro-Luminescence) image array.

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

  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, JP-A-5-279591 and the like; chlorogallium phthalocyanine disclosed in JP-A-5-98181 and the like; JP-A-5 Dichlorotin phthalocyanine disclosed in -140472, JP-A-5-140473 and the like; and titanyl phthalocyanine disclosed in JP-A-4-189873 and the like are more preferable.

  On the other hand, in order to cope with laser exposure in the near ultraviolet region, as charge generating materials, condensed aromatic pigments such as dibromoanthanthrone; thioindigo pigments; porphyrazine compounds; zinc oxide; trigonal selenium; The bisazo pigment etc. which were disclosed by 2004-78147 and Unexamined-Japanese-Patent No. 2005-181992 are preferable.

  Even when using an incoherent light source such as an LED or an organic EL image array having a central wavelength of light emission at 450 nm or more and 780 nm or less, the above charge generation material may be used, but from the viewpoint of resolution When used as a thin film, the electric field strength in the photosensitive layer becomes high, and charge reduction due to charge injection from the substrate tends to cause image defects called so-called black spots. This becomes remarkable when using a charge generating material which is a p-type semiconductor such as trigonal selenium, phthalocyanine pigment or the like and tends to cause dark current.

On the other hand, when an n-type semiconductor such as a fused aromatic pigment, a perylene pigment, or an azo pigment is used as a charge generation material, it is difficult to generate a dark current, and an image defect called black point can be suppressed even in a thin film. . Examples of the n-type charge generation material include compounds (CG-1) to (CG-27) described in paragraphs [0288] to [0291] of JP 2012-155282 A, and examples thereof It is not limited.
In addition, determination of n-type is determined by the polarity of the photocurrent which flows using the time of flight method normally used, and makes what is easy to flow an electron as a carrier rather than a hole be n-type.

The binder resin used for the charge generation layer is selected from a wide range of insulating resins, and the binder resin is selected from organic photoconductive polymers such as poly-N-vinylcarbazole, polyvinyl anthracene, polyvinyl pyrene, polysilane and the like. You may choose.
As the binder resin, for example, polyvinyl butyral resin, polyarylate resin (polycondensate of bisphenol and aromatic divalent carboxylic acid, etc.), polycarbonate resin, polyester resin, phenoxy resin, vinyl chloride-vinyl acetate copolymer, Polyamide resin, acrylic resin, polyacrylamide resin, polyvinyl pyridine resin, cellulose resin, urethane resin, epoxy resin, casein, polyvinyl alcohol resin, polyvinyl pyrrolidone resin, etc. may be mentioned. Here, "insulating" means that the volume resistivity is 10 ¹³ Ωcm or more.
These binder resins may be used alone or in combination of two or more.

  The compounding ratio of the charge generating material to the binder resin is preferably in the range of 10: 1 to 1:10 by mass ratio.

  The charge generation layer may further contain known additives.

  The formation of the charge generation layer is not particularly limited, and a known formation method is used. For example, a coating film of the charge generation layer forming coating solution obtained by adding the above components to a solvent is formed, and the coating film is dried. And by heating if necessary. Note that the charge generation layer may be formed by vapor deposition of a charge generation material. The formation of the charge generation layer by vapor deposition is particularly suitable when a fused aromatic pigment or perylene pigment is used as the charge generation material.

  As a solvent for preparing a coating solution for forming a charge generation layer, methanol, ethanol, n-propanol, n-butanol, benzyl alcohol, methyl cellosolve, ethyl cellosolve, acetone, methyl ethyl ketone, cyclohexanone, methyl acetate, acetic acid n And -butyl, dioxane, tetrahydrofuran, methylene chloride, chloroform, chlorobenzene, toluene and the like. These solvents are used singly or in combination of two or more.

As a method of dispersing particles (for example, charge generation material) in the coating liquid for charge generation layer formation, for example, media dispersion machines such as ball mill, vibration ball mill, attritor, sand mill, horizontal sand mill, stirring, ultrasonic dispersion machine Medialess dispersing machines such as roll mills and high pressure homogenizers are used. Examples of the high-pressure homogenizer include a collision method in which the dispersion is dispersed by causing liquid-liquid collision or liquid-wall collision in a high pressure state to disperse it, and a penetration method in which a fine flow path is dispersed by being dispersed in a high pressure state.
At the time of this dispersion, it is effective to set the average particle diameter of the charge generation material in the coating solution for forming a charge generation layer to 0.5 μm or less, preferably 0.3 μm or less, more preferably 0.15 μm or less. .

  As a method of applying the coating liquid for charge generation layer formation on the undercoat layer (or on the intermediate layer), for example, blade coating method, wire bar coating method, spray coating method, dip coating method, bead coating method, air knife coating And ordinary methods such as curtain coating method.

  The film thickness of the charge generation layer is, for example, preferably in the range of 0.1 μm to 5.0 μm, more preferably 0.2 μm to 2.0 μm.

(Charge transport layer)
The charge transport layer is, for example, a layer containing a charge transport material and a binder resin. The charge transport layer may be a layer containing a polymeric charge transport material.

  As charge transport materials, quinone compounds such as p-benzoquinone, chloranil, bromanyl, anthraquinone and the like; tetracyanoquinodimethane compounds; fluorenone compounds such as 2,4,7-trinitrofluorenone; xanthone compounds; benzophenone compounds Cyanovinyl compounds; electron transporting compounds such as ethylene compounds. Examples of the charge transporting material also include hole transporting compounds such as triarylamine compounds, benzidine compounds, arylalkane compounds, aryl substituted ethylene compounds, stilbene compounds, anthracene compounds, hydrazone compounds and the like. Although these charge transport materials are used individually by 1 type or in 2 or more types, it is not limited to these.

  From the viewpoint of charge mobility, a triarylamine derivative represented by the following structural formula (a-1) and a benzidine derivative represented by the following structural formula (a-2) are preferable as the charge transport material.

In structural formula (a-1), Ar ^T1 , Ar ^T2 and Ar ^T3 each independently represent a substituted or unsubstituted aryl group, -C ₆ H ₄ -C (R ^T4 ) = C (R ^T5 ) (R ^{T 5} ) ^T6), or _{-C 6 H 4 -CH = CH-} CH = C (R T7) shows the ^{(R T8).} R ^T4 , R ^T5 , R ^T6 , R ^T7 and R ^T8 each independently represent a hydrogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aryl group.
As a substituent of each said group, a halogen atom, a C1-C5 alkyl group, and a C1-C5 alkoxy group are mentioned. Moreover, as a substituent of said each group, the substituted amino group substituted by the C1-C3 alkyl group is also mentioned.

In Structural Formula (a-2), ^RT91 and ^RT92 each independently represent a hydrogen atom, a halogen atom, an alkyl group having 1 to 5 carbon atoms, or an alkoxy group having 1 to 5 carbon atoms. R ^T101 , R ^T102 , R ^T111 and R ^T112 are each independently ^substituted with a halogen atom, an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, an alkyl group having 1 to 2 carbon atoms A substituted amino group, a substituted or unsubstituted aryl group, -C ( ^RT12 ) = C ( ^RT13 ) ( ^RT14 ), or -CH = CH-CH = C ( ^RT15 ) ( ^RT16 ); R ^T12 , R ^T13 , R ^T14 , R ^T15 and R ^T16 each independently represent a hydrogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aryl group. Tm1, Tm2, Tn1 and Tn2 each independently represent an integer of 0 or more and 2 or less.
As a substituent of each said group, a halogen atom, a C1-C5 alkyl group, and a C1-C5 alkoxy group are mentioned. Moreover, as a substituent of said each group, the substituted amino group substituted by the C1-C3 alkyl group is also mentioned.

Here, among the triarylamine derivative represented by the structural formula (a-1) and the benzidine derivative represented by the structural formula (a-2), in particular, “—C ₆ H ₄ —CH = CH—CH = Triarylamine derivatives having C (R ^T7 ) (R ^T8 ), and benzidine derivatives having “—CH = CH—CH = C (R ^T15 ) (R ^T16 )” are preferred in view of charge mobility.

  As the polymer charge transport material, known materials having charge transportability such as poly-N-vinylcarbazole and polysilane are used. In particular, polyester-based polymer charge transport materials disclosed in JP-A-8-176293, JP-A-8-208820 and the like are particularly preferable. The polymer charge transport material may be used alone or in combination with a binder resin.

The binder resin used for the charge transport layer is 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 resin, poly-N -Vinylcarbazole, polysilane and the like can be mentioned. Among these, polycarbonate resin or polyarylate resin is suitable as the binder resin. These binder resins may be used alone or in combination of two or more.
The compounding ratio of the charge transport material to the binder resin is preferably 10: 1 to 1: 5 in mass ratio.

  The charge transport layer may further contain known additives.

  The formation of the charge transport layer is not particularly limited, and a known formation method is used. For example, a coating film of a charge transport layer forming solution obtained by adding the above components to a solvent is formed, and the coating film is dried. Perform by heating if necessary.

  As a solvent for preparing a coating liquid for charge transport layer formation, aromatic hydrocarbons such as benzene, toluene, xylene and chlorobenzene; ketones such as acetone and 2-butanone; methylene chloride, chloroform, ethylene chloride and the like Commonly used organic solvents such as halogenated aliphatic hydrocarbons; cyclic or linear ethers such as tetrahydrofuran and ethyl ether. These solvents are used alone or in combination of two or more.

  As a coating method at the time of coating the coating liquid for charge transport layer formation on the charge generation layer, blade coating method, wire bar coating method, spray coating method, dip coating method, bead coating method, air knife coating method, curtain A usual method such as a coating method may be mentioned.

  The thickness of the charge transport layer is, for example, preferably in the range of 5 μm to 50 μm, and more preferably in the range of 10 μm to 30 μm.

(Protective layer)
A protective layer is provided on the photosensitive layer as needed. The protective layer is provided, for example, for the purpose of preventing chemical change of the photosensitive layer during charging or further improving the mechanical strength of the photosensitive layer.
Therefore, as the protective layer, a layer formed of a cured film (crosslinked film) may be applied. Examples of these layers include the layers shown in the following 1) or 2).

1) A layer composed of a cured film of a composition containing a reactive group-containing charge transporting material having a reactive group and a charge transporting skeleton in the same molecule (that is, a polymer or a crosslink of the reactive group-containing charge transporting material Layer containing the body)
2) A layer composed of a cured film of a composition including a non-reactive charge transport material and a reactive group-containing non-charge transport material having no charge transport skeleton and having a reactive group (that is, A layer comprising a non-reactive charge transport material and a polymer or cross-linked product of the reactive group-containing non-charge transport material

As a reactive group of the reactive group-containing charge transporting material, a chain polymerizable group, an epoxy group, -OH, -OR (wherein R represents an alkyl group), -NH ₂ , -SH, -COOH, -SiR ^{Q 1} _3- ^Q _n (OR ^{Q 2} ) ^Q _n [wherein, R ^Q1 represents a hydrogen atom, an alkyl group, or a substituted or unsubstituted aryl group, and R ^Q2 represents a hydrogen atom, an alkyl group, or a trialkylsilyl group. Qn represents an integer of 1 to 3] and the like.

  The chain polymerizable group is not particularly limited as long as it is a radically polymerizable functional group, and is, for example, a functional group having a group containing at least a carbon double bond. Specific examples thereof include a group containing at least one selected from a vinyl group, a vinyl ether group, a vinyl thioether group, a styryl group (vinyl phenyl group), an acryloyl group, a methacryloyl group, and derivatives thereof. Among them, a group having at least one selected from a vinyl group, a styryl group (vinylphenyl group), an acryloyl group, a methacryloyl group, and derivatives thereof as the chain polymerizable group because of its excellent reactivity. Is preferred.

  The charge transporting skeleton of the reactive group-containing charge transporting material is not particularly limited as long as it has a known structure in an electrophotographic photosensitive member, and, for example, triarylamine compounds, benzidine compounds, hydrazone compounds, etc. And a structure derived from the nitrogen-containing hole-transporting compound of the above, which is conjugated to a nitrogen atom. Among these, a triarylamine skeleton is preferable.

  The reactive group-containing charge transporting material having the reactive group and the charge transporting skeleton, the nonreactive charge transporting material, and the reactive group-containing non-charge transporting material may be selected from known materials.

  The protective layer may further contain known additives.

  The formation of the protective layer is not particularly limited, and a known formation method is used. For example, a coating film of a coating solution for forming a protective layer obtained by adding the above components to a solvent is formed, and the coating film is dried. It is carried out by curing treatment such as heating if necessary.

As a solvent for preparing a coating solution for forming a protective layer, aromatic solvents such as toluene and xylene; ketone solvents such as methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone; ester solvents such as ethyl acetate and butyl acetate; tetrahydrofuran And ether solvents such as dioxane; cellosolv solvents such as ethylene glycol monomethyl ether; alcohol solvents such as isopropyl alcohol and butanol. These solvents are used alone or in combination of two or more.
The coating solution for forming a protective layer may be a non-solvent coating solution.

  As a method of applying a coating solution for forming a protective layer on a photosensitive layer (for example, charge transport layer), dip coating, push-up coating, wire bar coating, spray coating, blade coating, knife coating, curtain coating The usual methods such as the law can be mentioned.

  The film thickness of the protective layer is, for example, preferably in the range of 1 μm to 20 μm, more preferably 2 μm to 10 μm.

(Single-layer type photosensitive layer)
The single-layer type photosensitive layer (charge generation / charge transport layer) is, for example, a layer containing a charge generation material, a charge transport material, and, if necessary, a binder resin and other known additives. Note that these materials are the same as the materials described in the charge generation layer and the charge transport layer.
The content of the charge generation material in the single-layer type photosensitive layer is preferably 10% by mass to 85% by mass, and more preferably 20% by mass to 50% by mass, with respect to the total solid content. Further, the content of the charge transport material in the single-layer type photosensitive layer is preferably 5% by mass to 50% by mass with respect to the total solid content.
The method of forming the single-layer type photosensitive layer is the same as the method of forming the charge generation layer or the charge transport layer.
The film thickness of the single layer type photosensitive layer is, for example, 5 μm to 50 μm, and preferably 10 μm to 40 μm.

[Image forming apparatus (and process cartridge)]
The image forming apparatus according to the present embodiment includes an electrophotographic photosensitive member, a charging unit that charges the surface of the electrophotographic photosensitive member, and an electrostatic latent image 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 photosensitive member with a developer containing toner, thereby forming a toner image, and transfer means for transferring the toner image to the surface of the recording medium, Equipped with Then, the electrophotographic photosensitive member according to the present embodiment is applied as the electrophotographic photosensitive member.

  The image forming apparatus according to the present embodiment includes a fixing unit that fixes a toner image transferred to the surface of a recording medium; a direct transfer that directly transfers a toner image formed on the surface of an electrophotographic photosensitive member to a recording medium Type of device; primary transfer of the toner image formed on the surface of the electrophotographic photosensitive member to the surface of the intermediate transfer member, and secondary transfer of the toner image transferred onto the surface of the intermediate transfer member to the surface of the recording medium A device of the method; a device comprising a cleaning means for cleaning the surface of the electrophotographic photosensitive member before charging after transfer of the toner image; irradiating the surface of the electrophotographic photosensitive member with charge removing light before charging after transfer of the toner image A known image forming apparatus such as an apparatus including a discharging unit for discharging electricity; an apparatus including an electrophotographic photosensitive member heating member for raising the temperature of the electrophotographic photosensitive member and reducing the relative temperature is applied.

  However, after transfer of the toner image (that is, after the toner image formed on the surface of the electrophotographic photosensitive member is transferred by the transfer unit), before charging (that is, before the surface of the electrophotographic photosensitive member is charged by the charging unit) In the case where the charge removal means for removing the charge on the surface of the electrophotographic photosensitive member is not provided, in particular, charges are accumulated at the interface between the photosensitive layer and the undercoat layer, and a ghost tends to occur. However, by applying the electrophotographic photosensitive member according to the present embodiment, the occurrence of ghosting can be easily suppressed even when the charge removing unit is not provided.

  In the case of an intermediate transfer type apparatus, for example, an intermediate transfer member to which a toner image is transferred on the surface, and a primary transfer unit primary-transfers the toner image formed on the surface of the electrophotographic photosensitive member to the surface of the intermediate transfer member. A configuration including the transfer unit and a secondary transfer unit for secondarily transferring the toner image transferred to the surface of the intermediate transfer member 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 photosensitive member may have a cartridge structure (process cartridge) which is detachably attached to 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, in addition to the electrophotographic photosensitive member, 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.

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

FIG. 4 is a schematic configuration view showing an example of the image forming apparatus according to the present embodiment.
The image forming apparatus 100 according to the present embodiment, as shown in FIG. 4, includes a process cartridge 300 including an electrophotographic photosensitive member 7, an exposure device 9 (an example of an electrostatic latent image forming unit), and a transfer device 40 (primary). A transfer device) and an intermediate transfer member 50 are provided. In the image forming apparatus 100, the exposure device 9 is disposed from the opening of the process cartridge 300 at a position where exposure to the electrophotographic photosensitive member 7 is possible, and the transfer device 40 is the electrophotographic photosensitive member via the intermediate transfer member 50. The intermediate transfer member 50 is disposed so as to be 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 member 50 to a recording medium (for example, a sheet). The intermediate transfer member 50, the transfer device 40 (primary transfer device), and the secondary transfer device (not shown) correspond to an example of the transfer unit.

  In the process cartridge 300 shown in FIG. 4, the electrophotographic photosensitive member 7, the charging device 8 (an example of the charging means), the developing device 11 (an example of the developing means), and the cleaning device 13 (an example of the cleaning means) In favor of The cleaning device 13 has a cleaning blade (an example of a cleaning member) 131, and the cleaning blade 131 is disposed in contact with the surface of the electrophotographic photosensitive member 7. The cleaning member may be a conductive or insulating fibrous member instead of the cleaning blade 131, and may be used alone or in combination with the cleaning blade 131.

  In FIG. 4, as an image forming apparatus, a fibrous member 132 (roll-shaped) for supplying the lubricant 14 to the surface of the electrophotographic photosensitive member 7 and a fibrous member 133 for assisting cleaning (flat brush-shaped) An example is 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 charging device 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, non-contact type roller chargers, scorotron chargers utilizing corona discharge, corotron chargers, etc., per se known chargers and the like are also used.

-Exposure apparatus-
Examples of the exposure device 9 include an optical system device that exposes the surface of the electrophotographic photosensitive member 7 with light such as semiconductor laser light, LED light, liquid crystal shutter light, etc. in a defined image. The wavelength of the light source is in the spectral sensitivity region of the electrophotographic photosensitive member. As the wavelength of the semiconductor laser, near infrared light having an oscillation wavelength around 780 nm is the mainstream. However, the wavelength is not limited to this, and a laser having an oscillation wavelength of 400 nm or more and 450 nm or less may be used as an oscillation wavelength laser of about 600 nm or a blue laser. In addition, a surface emitting laser light source of a type capable of outputting multiple beams is also effective for color image formation.

-Development device-
Examples of the developing device 11 include, for example, a general developing device which develops with a developer in contact or non-contact. The developing device 11 is not particularly limited as long as it has the above-described function, and is selected according to the purpose. For example, a known developing device or the like having a function of causing the one-component developer or the two-component developer to adhere to the electrophotographic photosensitive member 7 using a brush, a roller or the like can be mentioned. Among them, one using a developing roller holding a developer on the surface is preferable.

  The developer used in the developing device 11 may be a single component developer of toner alone, or may be a two component developer including toner and carrier. The developer may be magnetic or nonmagnetic. As these developers, known ones are applied.

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

-Transfer device-
The transfer device 40 may be, for example, a contact type transfer charger using a belt, a roller, a film, a rubber blade or the like, a scorotron transfer charger using corona discharge, a corotron transfer charger, etc. It can be mentioned.

-Intermediate transfer body-
As the intermediate transfer member 50, a belt-like member (intermediate transfer belt) containing semiconductive conductive polyimide, polyamideimide, polycarbonate, polyarylate, polyester, rubber and the like is used. The intermediate transfer member may be in the form of a drum other than the belt.

FIG. 5 is a schematic configuration view showing another example of the image forming apparatus according to the present embodiment.
An image forming apparatus 120 shown in FIG. 5 is a tandem 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. The image forming apparatus 120 has the same configuration as that of the image forming apparatus 100 except that the image forming apparatus 120 is a tandem system.

  The image forming apparatus 100 according to the present embodiment is not limited to the above configuration. For example, the cleaning device may be around the electrophotographic photosensitive member 7 and downstream of the transfer device 40 in the rotational direction of the electrophotographic photosensitive member 7. Alternatively, the first charge removing device may be provided on the upstream side of the electrophotographic photosensitive member in the rotational direction of the electrophotographic photosensitive member 13 so as to make the polarity of the remaining toner uniform and to be easily removed by the cleaning brush. The second charge removing device for removing the surface of the electrophotographic photosensitive member 7 may be provided on the downstream side of the rotating direction of the electrophotographic photosensitive member and further upstream of the charging device 8 in the rotating direction of the electrophotographic photosensitive member than the charging device 8. .

  Further, the image forming apparatus 100 according to the present embodiment is not limited to the above configuration, and a known configuration, for example, a direct transfer type image forming apparatus for directly transferring a toner image formed on the electrophotographic photosensitive member 7 to a recording medium. It may be adopted.

  Hereinafter, the present embodiment will be described in detail by way of examples, but the present embodiment is not limited to these examples. In the following description, "parts" and "%" are all based on mass unless otherwise noted.

Example 1
[Formation of undercoat layer]
100 parts by mass of zinc oxide particles (trade name: MZ-300, manufactured by Tayca Corporation, average primary particle diameter: 35 nm) as metal oxide particles, N-β (aminoethyl) γ-aminopropyltritrile as a silane coupling agent The 10 mass parts toluene solution of ethoxysilane: 10 mass parts and toluene: 200 mass parts were mixed, stirring was performed, and reflux was performed for 2 hours. Then, toluene was distilled off under reduced pressure at 10 mmHg, and baking was performed at 135 ° C. for 2 hours to perform surface treatment.

  Surface-treated zinc oxide: 33 parts by mass, blocked isocyanate (trade name: SUMIDUR 3175, manufactured by Sumitomo Bavaria Urethane Co., Ltd.): 6 parts by mass, anthraquinone-based electron accepting property represented by the formula (EK) as an electron accepting compound Compound: 1 part by mass and methyl ethyl ketone: 25 parts by mass are mixed for 30 minutes, and then butyral resin (trade name: S-Lec BM-1, manufactured by Sekisui Chemical Co., Ltd.): 5 parts by mass, silicone ball (trade name: Tospearl 120) Momentary Performance Materials Co., Ltd .: 3 parts by mass, silicone oil (trade name: SH29PA, Toray Dow Corning Silicone Co., Ltd.) as a leveling agent: 0.01 parts by mass, and dispersion for 3 hours in a sand mill To obtain a coating solution for forming an undercoat layer.

  Using the obtained undercoat layer forming coating solution, it is applied onto an aluminum substrate with a diameter of 30 mm, a length of 340 mm, and a thickness of 1.0 mm by dip coating, and dried and cured at 200 ° C. for 30 minutes. A 23.5 μm thick undercoat layer was obtained.

[Formation of Charge Generating Layer]
Next, 18 parts by mass of a hydroxygallium phthalocyanine pigment as a charge generation material, 16 parts by mass of a vinyl chloride-vinyl acetate copolymer resin (trade name: VMCH, manufactured by Nippon Unicar Co., Ltd.) as a binder resin, and n-butyl acetate A mixture consisting of 100 parts by mass was placed in a 100 mL glass bottle with a 1.0 mm diameter glass bead at a filling rate of 50%, and dispersed for 2.5 hours with a paint shaker to obtain a coating solution for charge generation layer. The obtained coating solution was dip-coated on the undercoat layer and dried at 100 ° C. for 5 minutes to form a charge generation layer having a thickness of 0.20 μm.

[Formation of charge transport layer]
Next, a compound represented by the following formula (CT1): 2 parts by mass, a compound represented by the following formula (CT2): 2 parts by mass, and a polycarbonate copolymer resin represented by the following formula (PC1) (molecular weight 4 6) 60 parts by weight of tetrahydrofuran was added and dissolved to obtain a charge transport layer forming coating solution; the obtained charge transport layer forming coating solution was dip coated on the charge generating layer By drying at 150 ° C. for 30 minutes, a charge transport layer having a thickness of 24 μm was formed.

  Through the above steps, an electrophotographic photosensitive member of Example 1 was obtained.

Examples 2 to 6 and Comparative Examples 1 to 4
The electrophotographic photosensitive members of Examples 2 to 6 and Comparative Examples 1 to 4 were obtained in the same manner as in Example 1 except that the conditions of Table 1 were changed.

<Evaluation>
The following evaluation was carried out on the obtained electrophotographic photosensitive member.

(Dissolution amount of electron accepting compound)
The "elution amount of the electron accepting compound" in the undercoat layer was measured according to the method described above.

(Inclusion of electron accepting compound into charge generation layer)
The contamination of the charge generation layer with the electron accepting compound was evaluated as follows.
A part of the charge generation layer is collected from the photosensitive member, and the collected measurement sample is immersed in a mixed solvent (liquid temperature 22 ° C. (room temperature)) having a mass ratio of 7: 3 of butyl acetate and mesoisobutyl ketone in mass ratio The solvent and the measurement sample were separated. The immersion time is 5 minutes. Next, the absorption spectrum (UV-VIS) of an ultraviolet and visible light area | region is measured by Hitachi Ltd. make, ultraviolet visible spectrophotometer U-4100 form using the obtained mixed solvent. Then, the elution amount of the electron accepting substance eluted in the mixed solvent was calculated from calibration curves prepared by dissolving various electron accepting substances in the mixed solvent at various concentrations. Then, the elution amount of the electron accepting substance was evaluated as the contamination amount of the electron accepting compound in the charge generation layer according to the following criteria.
-Evaluation criteria-
A (○): Elution amount of electron accepting substance is 1.0 × 10 ⁻⁵ (g) or less NG (×): Elution amount of electron accepting substance exceeds 1.0 × 10 ⁻⁵ (g)

(Electrical characteristics)
The electrophotographic photosensitive member was evaluated as follows.
First, the surface of the electrophotographic photosensitive member obtained in each example and each comparative example was negatively charged to -700 V by a scorotron charger. Next, the negatively charged electrophotographic photosensitive member is irradiated with light for exposure (light source: semiconductor laser, wavelength 780 nm, output 5 mW) to perform charge removal, and the potential attenuation rate per unit light quantity (V · m ² / From mJ), the photoreceptor surface potential was evaluated at an amount of light equivalent to 4 mJ / m ² . And it evaluated by the next standard.
In addition, the electrical property was implemented by both initial stage (after 10 sheet output) and time-lapse (after 1000 sheet output).
-Evaluation criteria-
A (○): The potential difference between initial and time is less than 5V.
B (Δ): The potential difference between initial and time is 5V or more and less than 15V.
NG (×): The potential difference between initial and time is 5V or more and 15V or more.

(Concentration tone)
The electrophotographic photosensitive member obtained in each example was mounted on an image forming apparatus (manufactured by Fuji Xerox Co., Ltd .: printer DocuPrint CP210 dw).
With this apparatus, 1000 sheets of halftone images are output on A3 in 10% increments in the range of 10% to 90% of image density. Then, with respect to the density gradation of the images of the 10th sheet (initial) and the 1000th sheet (temporary), the gradation was evaluated based on the following criteria. The image density was measured using an X-Rite 404 manufactured by X-Rite.
-Evaluation criteria-
A (○): difference between the target image density and the actual image density formed is less than 5% B (Δ): difference between the target image density and the actual image density formed is 5% or more and less than 10% NG (× ): The difference between the target image density and the actual image density printed is 10% or more

  The details of each example are listed in Table 1 below. The details of the abbreviations and the like in Table 1 are as follows.

· HK: anthraquinone electron accepting compound represented by the formula (EK) · HA: anthraquinone electron accepting compound represented by the formula (EA)

From the above results, the electrophotographic photosensitive member of the present example is superior to the electrophotographic photosensitive member of the comparative example from the beginning to the time, and has excellent electric characteristics and density gradation, and an image formed when an image is formed repeatedly It can be seen that concentration fluctuations are suppressed.
In addition, the electrophotographic photosensitive member of the present example is superior to the electrophotographic photosensitive members of Comparative Examples 2 and 4 in density gradation from the initial stage of image formation, and the target image density is obtained in the initial stage of image formation. It is understood that it is easy to
In addition, it is also understood that the electrophotographic photosensitive member of the present example has less contamination of the electron accepting compound in the charge generation layer.

DESCRIPTION OF SYMBOLS 1 subbing layer, 2 charge generation layer, 3 charge transport layer, 4 conductive substrate, 6 single layer type photosensitive layer, 7 electrophotographic photosensitive member, 8 charging device, 9 exposure device, 11 developing device, 13 cleaning device, 14 Lubricant, 40 transfer device, 50 intermediate transfer member, 100 image forming device, 120 image forming device, 131 cleaning blade, 132 fibrous member, 133 fibrous member, 300 process cartridge

Claims (10)

A conductive substrate,
The undercoating layer provided on the conductive substrate, which contains a binder resin, metal oxide particles, and an electron accepting compound, and is immersed in a mixed solvent of butyl acetate and methyl isobutyl ketone at a mass ratio of 7: 3. An undercoat layer having an elution amount of 1 × 10 ⁻⁷ g to 1 × 10 ⁻⁵ g per 1 g of the undercoat layer;
A photosensitive layer provided on the undercoat layer;
An electrophotographic photosensitive member having   The electrophotographic photosensitive member according to claim 1, wherein the electron accepting compound is an electron accepting compound having a reactive group.   The electrophotographic photosensitive member according to claim 2, wherein the electron accepting compound having a reactive group is an electron accepting compound having an OH group. The electrophotographic photosensitive member according to claim 3, wherein the electron accepting compound having an OH group is an electron accepting compound represented by the following general formula (1A).

(In general formula (1A), R ¹¹ represents a hydrogen atom, an alkoxy group having 1 to 10 carbon atoms, or an aryl group having 6 to 30 carbon atoms, and n represents an integer of 1 to 7). )   The electrophotographic photosensitive member according to any one of claims 1 to 4, wherein the metal oxide particles are metal oxide particles surface-treated with a coupling agent having an amino group.   The electrophotographic photosensitive member according to claim 5, wherein the metal oxide particles surface-treated with the coupling agent are zinc oxide particles.   The electrophotographic photosensitive member according to any one of claims 1 to 6, wherein the binder resin is a crosslinked resin.   The electrophotographic photosensitive member according to claim 7, wherein the crosslinked resin is a polyurethane resin. An electrophotographic photosensitive member according to any one of claims 1 to 8.
Process cartridge to be attached to and removed from the image forming apparatus. An electrophotographic photosensitive member according to any one of claims 1 to 8.
Charging means for charging the surface of the electrophotographic photosensitive member;
Electrostatic latent image forming means for forming an electrostatic latent image on the surface of the electrophotographic photosensitive member charged;
Developing means for developing an electrostatic latent image formed on the surface of the electrophotographic photosensitive member with a developer containing toner to form a toner image;
A transfer unit that transfers the toner image to the surface of a recording medium;
An image forming apparatus comprising: