JP2020154141A - Electrophotographic photoreceptor, process cartridge and image formation apparatus - Google Patents

Abstract

To provide an electrophotographic photoreceptor that is suppressed from decreasing in photoreceptor lifetime and also has an afterimage phenomenon suppressed from being caused as a history of a previous image is left.SOLUTION: An electrophotographic photoreceptor 7A has: a conductive base body 4; and a photosensitive layer 5 which is provided on the conductive base body 4 and includes fluororesin particles and a dispersant having fluorine atoms, the ratio of present amounts Xf and Xr measured by an X-ray photoelectron spectroscopic analysis method satisfying the relation Xf/Xr≥1.04, where Xf is the present amount of the dispersant having the fluorine atoms to the fluororesin particles on a surface side, and Xr is the present amount of the dispersant having the fluorine atoms to the fluororesin particles on a conductive base body side.SELECTED DRAWING: Figure 1

Description

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

Conventionally, as an electrophotographic image forming apparatus, an electrophotographic photosensitive member (hereinafter, may be referred to as a “photoreceptor”) is used to sequentially perform processes such as charging, electrostatic latent image formation, development, transfer, and cleaning. The device to do is widely known.

Patent Document 1 states that "an organic photoconductor having at least a photosensitive layer on a conductive substrate, the surface layer contains fluororesin fine particles having an average primary particle size of 0.2 μm or less, and the fluororesin fine particles are the surface. An electrophotographic photosensitive member is disclosed in which agglomerates having a major axis of 0.35 μm or more are dispersed in a layer in a dispersed state of 5 or less in a range of 2 μm square. ”

Japanese Unexamined Patent Publication No. 2005-099438

Conventionally, in an electrophotographic photosensitive member having a photosensitive layer containing fluororesin particles, a fluorine-containing dispersant has been used to disperse the fluororesin particles contained in the photosensitive layer. When an image is formed by an image forming apparatus to which an electrophotographic photosensitive member having a photosensitive layer containing fluororesin particles and a fluorine-containing dispersant is applied, the life of the photoconductor is shortened and the afterimage caused by the history of the previous image remains. Occurrence of the phenomenon may occur.

An object of the present invention is to determine the abundance Xf of a dispersant having a fluorine atom with respect to the fluororesin particles on the surface side of the photosensitive layer in an electrophotographic photosensitive member having a photosensitive layer containing fluororesin particles and a fluorine-containing dispersant. The decrease in the life of the photoconductor is suppressed as compared with the case where the ratio (Xf / Xr) of the abundance amount Xr of the dispersant having a fluorine atom to the fluororesin particles on the photosensitive layer conductive substrate side is less than 1.04. At the same time, it is an object of the present invention to provide an electrophotographic photosensitive member in which the occurrence of the afterimage phenomenon caused by the history of the previous image is suppressed.

The above problem is solved by the following means.

<1>
With a conductive substrate
A photosensitive layer provided on the conductive substrate and containing fluororesin particles and a dispersant having fluorine atoms, which is measured by X-ray photoelectron spectroscopic analysis and has the fluorine atoms relative to the fluororesin particles on the surface side. When the abundance amount Xf of the dispersant having a fluorine atom and the abundance amount Xr of the dispersant having a fluorine atom with respect to the fluororesin particles on the conductive substrate side, the abundance ratio of the Xf and the Xr is Xf / Xr ≧. A photosensitive layer satisfying the relationship of 1.04 and
An electrophotographic photosensitive member having.
<2>
The electrophotographic photosensitive member according to <1>, wherein the content of the dispersant having a fluorine atom in the entire photosensitive layer is 5% by mass or more and 40% by mass or less with respect to the fluororesin particles.
<3>
The electrophotographic photosensitive member according to <2>, wherein the content of the dispersant having a fluorine atom in the entire photosensitive layer is 5% by mass or more and 35% by mass or less with respect to the fluororesin particles.
<4>
The electrophotographic photosensitive member according to any one of <1> to <3>, wherein the content of the fluororesin particles is 5% by mass or more and 20% by mass or less with respect to the total solid content of the photosensitive layer.
<5>
The electrophotographic photosensitive member according to <4>, wherein the content of the fluororesin particles is 6% by mass or more and 10% by mass or less with respect to the total solid content of the photosensitive layer.
<6>
The electrophotographic photosensitive member according to any one of <1> to <5>, wherein the Xf is 0.50% or more and 9.80% or less.
<7>
The electrophotographic photosensitive member according to any one of <1> to <6>, wherein the Xr is 0.40% or more and 3.60% or less.
<8>
The electrophotographic photosensitive member according to any one of <1> to <7> is provided.
A process cartridge that attaches to and detaches from the image forming device.
<9>
The electrophotographic photosensitive member according to any one of <1> to <7>,
A charging means for charging the surface of the electrophotographic photosensitive member and
An electrostatic latent image forming means for forming an electrostatic latent image on the surface of the charged electrophotographic photosensitive member,
A 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, and a developing means.
A transfer means for transferring the toner image to the surface of a recording medium, and
An image forming apparatus comprising.

According to the invention according to <1>, in an electrophotographic photosensitive member having a photosensitive layer containing fluororesin particles and a fluorine-containing dispersant, the presence of the dispersant having the fluorine atom with respect to the fluororesin particles on the surface side of the photosensitive layer. Compared with the case where the ratio (Xf / Xr) of the amount Xf to the abundance Xr of the dispersant having a fluorine atom with respect to the fluororesin particles on the photosensitive layer conductive substrate side is less than 1.04, the life of the photoconductor Provided is an electrophotographic photosensitive member in which the deterioration is suppressed and the occurrence of the afterimage phenomenon caused by the history of the previous image is suppressed.
According to the inventions <2> and <3>, when the content of the dispersant having a fluorine atom in the entire photosensitive layer is less than 5% by mass or more than 40% by mass with respect to the fluororesin particles. In comparison, there is provided an electrophotographic photosensitive member in which a decrease in the life of the photoconductor is suppressed and the occurrence of an afterimage phenomenon caused by the history of the previous image is suppressed.
According to the inventions <4> and <5>, the lifetime of the photoconductor is longer than that in the case where the content of the fluororesin particles is less than 5% by mass or more than 20% by mass with respect to the total solid content of the photosensitive layer. Provided is an electrophotographic photosensitive member in which a decrease is suppressed and the occurrence of an afterimage phenomenon caused by a history of a previous image is suppressed.
According to the invention according to <6>, the abundance Xf of the dispersant having a fluorine atom with respect to the fluororesin particles on the surface side of the photosensitive layer and the fluorine atom with respect to the fluororesin particles on the conductive substrate side of the photosensitive layer are provided. An electrophotographic photosensitive member having an Xf of 0.50% or more and 9.80% or less as compared with the case where the ratio (Xf / Xr) of the dispersant to the abundance amount Xr is less than 1.04. Provided is an electrophotographic photosensitive member in which a decrease in life is suppressed and the occurrence of an afterimage phenomenon caused by leaving a history of a previous image is suppressed.
According to the invention according to <7>, the abundance Xf of the dispersant having a fluorine atom with respect to the fluororesin particles on the surface side of the photosensitive layer and the fluorine atom with respect to the fluororesin particles on the conductive substrate side of the photosensitive layer are provided. An electrophotographic photosensitive member having an Xr of 0.40% or more and 3.60 or less as compared with the case where the ratio (Xf / Xr) with the abundance amount of the dispersant Xr is less than 1.04, and the photoconductor life Provided is an electrophotographic photosensitive member in which the decrease in the amount of the fluoropolymer is suppressed and the occurrence of the afterimage phenomenon caused by the history of the previous image is suppressed.
According to the invention according to <8> or <9>, in an electrophotographic photosensitive member having a photosensitive layer containing fluororesin particles and a fluorine-containing dispersant, the electrophotographic photosensitive member has the fluorine atom with respect to the fluororesin particles on the surface side of the photosensitive layer. Compared with the case where the ratio (Xf / Xr) of the abundance amount Xf of the dispersant to the abundance amount Xr of the dispersant having a fluorine atom to the fluororesin particles on the photosensitive layer conductive substrate side is less than 1.04. Provided is a process cartridge or an image forming apparatus to which an electrophotographic photosensitive member is applied, in which a decrease in the life of the photoconductor is suppressed and the occurrence of an afterimage phenomenon caused by the history of the previous image is suppressed.

It is a schematic cross-sectional view which shows an example of the layer structure of the electrophotographic photosensitive member of this embodiment. It is a schematic block diagram which shows an example of the image forming apparatus which concerns on this embodiment. It is a schematic block diagram which shows another example of the image forming apparatus which concerns on this embodiment.

Hereinafter, embodiments that are an example of the present invention will be described.

<Electrophotophotoreceptor>
The electrophotographic photosensitive member (hereinafter, may be referred to as a photosensitive member) according to the present embodiment is a photosensitive substrate and is provided on the conductive substrate and contains fluororesin particles and a dispersant having fluorine atoms. Has layers.
Then, the photosensitive layer has the abundance Xf of the dispersant having the fluorine atoms with respect to the fluororesin particles on the surface side and the fluorine atoms with respect to the fluororesin particles on the conductive substrate side, which are measured by X-ray photoelectron spectroscopy. When the abundance amount Xr of the dispersant having the above is assumed, the abundance ratio of the Xf and the Xr satisfies the relationship of Xf / Xr ≧ 1.04.

Conventionally, in an electrophotographic photosensitive member, in order to reduce the amount of wear of the photosensitive layer, the photosensitive layer may contain fluororesin particles. Then, in order to enhance the dispersibility of the fluororesin particles in the photosensitive layer, a dispersant having a fluorine atom (hereinafter, may be referred to as a fluorine-containing dispersant) is contained together with the fluororesin particles.

However, since the fluorine-containing dispersant contained in the photosensitive layer acts as a charge trap site (that is, a region where charges are likely to be accumulated), if the content of the fluorine-containing dispersant in the photosensitive layer is too large, the charge trap site Will increase. As the number of charge trap sites in the photosensitive layer increases, the charge transport capacity decreases, charges tend to accumulate in the photosensitive layer, and the residual potential increases when repeated images are formed, so that the history of the previous image becomes longer. Afterimage phenomenon (hereinafter, sometimes referred to as ghost) that occurs due to remaining is likely to occur. Further, the surface of the photoconductor is worn, and the life of the photoconductor is shortened.

On the other hand, in the electrophotographic photosensitive member according to the present embodiment, the above-mentioned configuration suppresses a decrease in the life of the photoconductor and suppresses the generation of ghosts. This factor is not always clear, but it is presumed as follows.

By moving the fluorine-containing dispersant to the surface side of the photosensitive layer while maintaining the dispersibility of the fluororesin particles in the photosensitive layer, the fluorine-containing dispersant moved to the surface side of the photosensitive layer and the charge on the surface of the photoconductor The distance becomes closer. Therefore, the electric charge easily moves in the photosensitive layer, and the decrease in the residual potential is suppressed. Further, in the process of repeatedly forming an image, the surface of the photosensitive layer is scraped in the cleaning process. As a result, the amount of the fluorine-containing dispersant in the photosensitive layer in which the fluorine-containing dispersant has moved to the surface side of the photosensitive layer is also reduced, so that the charge trap sites in the photosensitive layer are reduced. That is, the abundance Xf of the dispersant having the fluorine atom with respect to the fluororesin particles on the surface side of the photosensitive layer is the abundance Xr of the dispersant having the fluorine atom with respect to the fluororesin particles on the conductive substrate side of the photosensitive layer. By setting the ratio of the abundance ratio (Xf / Xr) of Xf to Xr to a specific ratio or more, the charge trap site in the photosensitive layer is lowered. As a result, it is considered that the decrease in the life of the photoconductor is suppressed and the generation of ghosts is suppressed.

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 partial cross-sectional view schematically showing an example of the layer structure of the electrophotographic photosensitive member according to the present embodiment.

The electrophotographic photosensitive member 7A shown in FIG. 1 has a structure in which an undercoat layer 1, a charge generation layer 2, and a charge transport layer 3 are laminated in this order on a conductive substrate 4. The charge generation layer 2 and the charge transport layer 3 constitute the photosensitive layer 5. In the electrophotographic photosensitive member 7A, the charge transport layer 3 provided on the charge generation layer 2 contains fluororesin particles and a fluorine-containing dispersant. When the charge transport layer 3 is measured by X-ray photoelectron spectroscopic analysis, the abundance Xf of the fluorine-containing dispersant with respect to the fluorine resin particles on the surface side of the charge transport layer 3 and the conductive substrate 4 side of the charge transport layer 3 The ratio (Xf / Xr) of the abundance of the dispersant having a fluorine atom to the fluorine resin particles to Xr satisfies the relationship of Xf / Xr ≧ 1.04. The electrophotographic photosensitive member 7A may have a layer structure in which the undercoat layer 1 is not provided. Further, the electrophotographic photosensitive member 7A may be provided with another layer, if necessary. Examples of other layers include a protective layer provided on the outer peripheral surface of the charge transport layer 3. The electrophotographic photosensitive member according to the present embodiment is not limited to the structure shown in FIG. 1, and the photosensitive layer may be a single-layer photosensitive layer.

The electrophotographic photosensitive member 7A shown in FIG. 1 shows a case where the outermost surface layer is the charge transport layer 3, but the layer corresponding to the outermost surface layer contains fluorine resin particles and a dispersant having fluorine atoms. The ratio (Xf / Xr) of the abundance Xf of the fluorine-containing dispersant to the fluorine resin particles on the surface side and the abundance Xr of the dispersant having a fluorine atom to the fluorine resin particles on the conductive substrate side is Xf / Xr ≧. The relationship of 1.04 may be satisfied. For example, when the outermost surface layer is a protective layer, the relationship between Xf and Xr may satisfy the same relationship. For example, when the photosensitive layer is a single-layer photosensitive layer, the relationship between Xf and Xr. May satisfy a similar relationship.

Hereinafter, each layer of the photoconductor 7A shown in FIG. 1 will be described in detail as an example of the electrophotographic photosensitive member according to the present embodiment. The reference numerals will be omitted.

(Conductive substrate)
Examples of the conductive substrate include metal plates containing metals (aluminum, copper, zinc, chromium, nickel, molybdenum, vanadium, indium, gold, platinum, etc.) or alloys (stainless steel, etc.), metal drums, metal belts, and the like. Can be mentioned. Examples of the conductive substrate include paper, resin film, belt, etc. coated, vapor-deposited, or laminated with a conductive compound (for example, conductive polymer, indium oxide, etc.), metal (for example, aluminum, palladium, gold, etc.) or alloy. Can also be mentioned. Here, "conductive" means that the volume resistivity is less than 10 ¹³ Ωcm.

When an electrophotographic photosensitive member is used in a laser printer, the surface of the conductive substrate has a centerline average roughness Ra of 0.04 μm or more and 0.5 μm for the purpose of suppressing interference fringes generated when irradiating the laser beam. It is preferable that the surface is roughened below. When non-interfering light is used as the light source, roughening to prevent interference fringes is not particularly necessary, but it is suitable for longer life because it suppresses the occurrence of defects due to the unevenness of the surface of the conductive substrate.

Roughening methods include, for example, wet honing performed by suspending an abrasive in water and spraying it onto a conductive substrate, and centerless grinding in which a conductive substrate is pressed against a rotating grindstone and continuously ground. , Anodization treatment and the like.

As a method of roughening, the conductive or semi-conductive powder is dispersed in the resin without roughening the surface of the conductive substrate to form a layer on the surface of the conductive substrate. Another method is to roughen the surface with particles dispersed in the layer.

In the roughening treatment by anodic oxidation, an oxide film is formed on the surface of the conductive substrate by anodicating in an electrolyte solution using a conductive substrate made of metal (for example, aluminum) as an anode. Examples of the electrolyte solution include sulfuric acid solution, oxalic acid solution and the like. 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 depending on the environment. Therefore, for the porous anodic oxide film, the micropores of the oxide film are closed by volume expansion due to the hydration reaction in pressurized steam or boiling water (a metal salt such as nickel may be added), and more stable hydration oxidation is performed. It is preferable to perform a sealing treatment to change the material.

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

The conductive substrate may be treated with an acidic treatment liquid or a boehmite treatment.
The treatment with the acidic treatment liquid 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 phosphoric acid in the acidic treatment liquid is, for example, phosphoric acid in the range of 10% by mass or more and 11% by mass or less, chromic acid in the range of 3% by mass or more and 5% by mass or less, and phosphoric acid It is preferably in the range of 0.5% by mass or more and 2% by mass or less, and the total concentration of these acids is in the range of 13.5% by mass or more and 18% by mass or less. The treatment temperature is preferably, for example, 42 ° C. or higher and 48 ° C. or lower. The film thickness of the coating is preferably 0.3 μm or more and 15 μm or less.

The boehmite treatment is carried out, for example, by immersing in pure water at 90 ° C. or higher and 100 ° C. or lower for 5 to 60 minutes, or by contacting with heated steam at 90 ° C. or higher and 120 ° C. or lower for 5 to 60 minutes. The film thickness of the coating is preferably 0.1 μm or more and 5 μm or less. This can be further anodized with an electrolyte solution having low film solubility such as adipic acid, boric acid, borate, phosphate, phthalate, maleate, benzoate, tartaric acid, and citrate. 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 resistivity (volume resistivity) of 10 ² Ωcm or more and 10 ¹¹ Ωcm or less.
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 by the BET method is, for example, preferably 10 m ² / g or more.
The volume average particle size of the inorganic particles is, for example, 50 nm or more and 2000 nm or less (preferably 60 nm or more and 1000 nm or less).

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

The inorganic particles may be surface-treated. As the inorganic particles, those having different surface treatments or those having different particle diameters may be mixed and used.

Examples of the surface treatment agent include a silane coupling agent, a titanate-based coupling agent, an aluminum-based coupling agent, a surfactant and the like. In particular, 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 thereof include, but are not limited to, propylmethyldimethoxysilane, N, N-bis (2-hydroxyethyl) -3-aminopropyltriethoxysilane, and the like.

Two or more kinds of silane coupling agents may be mixed and used. For example, a silane coupling agent having an amino group may be used in combination with another silane coupling agent. Examples of other silane coupling agents include vinyltrimethoxysilane, 3-methacryloxypropyl-tris (2-methoxyethoxy) silane, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, and 3-glyceride. 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 can be mentioned, but are limited thereto. It's not a thing.

The surface treatment method using a 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, for example, preferably 0.5% by mass or more and 10% by mass or less with respect to the inorganic particles.

Here, it is preferable that the undercoat layer contains an electron-accepting compound (acceptor compound) together with the inorganic particles from the viewpoint of enhancing the long-term stability of the electrical characteristics and the carrier blocking property.

Examples of the electron-accepting compound include quinone compounds such as chloranyl and bromoanyl; tetracyanoquinodimethane compounds; 2,4,7-trinitrofluorenone, 2,4,5,7-tetranitro-9-fluorenone and the like. Fluolenone compounds; 2- (4-biphenyl) -5- (4-t-butylphenyl) -1,3,4-oxadiazole, 2,5-bis (4-naphthyl) -1,3,4- Oxadiazole compounds such as oxadiazole, 2,5-bis (4-diethylaminophenyl) -1,3,4 oxadiazole; xanthone compounds; thiophene compounds; 3,3', 5,5'tetra- Examples thereof include electron-transporting substances such as diphenoquinone compounds such as t-butyldiphenoquinone;
In particular, as the electron accepting compound, a compound having an anthraquinone structure is preferable. 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, anthralfin, purpurin and the like are preferable.

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

Examples of the method for adhering 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 having a large shearing force, an electron-accepting compound dissolved directly or in an organic solvent is dropped and sprayed together with dry air or nitrogen gas to obtain an electron-accepting compound. This is a method of adhering to the surface of inorganic particles. When dropping or spraying the electron-accepting compound, it is preferable to carry out at a temperature equal to or lower than the boiling point of the solvent. After dropping or spraying the electron-accepting compound, it may be further baked at 100 ° C. or higher. The printing is not particularly limited as long as the temperature and time at which the electrophotographic characteristics can be obtained.

In the wet method, for example, an electron-accepting compound is added while dispersing inorganic particles in a solvent by stirring, ultrasonic waves, a sand mill, an attritor, a ball mill, or the like, and after stirring or dispersing, the solvent is removed to remove electrons. This is a method of adhering an accepting compound to the surface of inorganic particles. The solvent removing method is distilled off, for example, by filtration or distillation. After removing the solvent, baking may be further performed at 100 ° C. or higher. The printing is not particularly limited as long as the temperature and 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 electron-accepting compound is added. Examples thereof include a method of removing by stirring and heating in a solvent, and a method of removing by azeotropically boiling with a solvent. Can be mentioned.

The electron-accepting compound may be attached before or after the surface treatment with the surface treatment agent is applied to the inorganic particles, and the electron-accepting compound may be attached and the surface treatment with the surface treatment agent may be performed at the same time.

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

Examples of the binder resin used for the undercoat layer include acetal resin (for example, polyvinyl butyral), polyvinyl alcohol resin, polyvinyl acetal resin, casein resin, polyamide resin, cellulose resin, gelatin, polyurethane resin, polyester resin, and 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, and epoxy resin; zirconium chelate compound; titanium chelate compound; aluminum chelate compound; titanium alkoxide compound; organic titanium compound; known materials such as silane coupling agent can be mentioned.
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 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. Thermo-curable resins such as resins, alkyd resins, epoxy resins; with at least one resin selected from the group consisting of polyamide resins, polyester resins, polyether resins, methacrylic resins, acrylic resins, polyvinyl alcohol resins and polyvinyl acetal resins. A resin obtained by reacting with a curing agent is preferable.
When two or more of these binder resins are used in combination, the mixing ratio thereof is set as necessary.

The undercoat layer may contain various additives for improving electrical characteristics, environmental stability, and image quality.
Examples of the additive include known materials such as electron-transporting pigments such as polycyclic condensation type and azo type, zirconium chelate compound, titanium chelate compound, aluminum chelate compound, titanium alkoxide compound, organic titanium compound, and silane coupling agent. Be done. The silane coupling agent is used for surface treatment of 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, 3-. Glycydoxypropyltrimethoxysilane, vinyltriacetoxysilane, 3-mercaptopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-2- (aminoethyl) -3-aminopropyltrimethoxysilane, N-2- Examples thereof include (aminoethyl) -3-aminopropylmethyldimethoxysilane, N, N-bis (2-hydroxyethyl) -3-aminopropyltriethoxysilane, and 3-chloropropyltrimethoxysilane.

Examples of the zirconium chelate compound include zirconium butoxide, zirconium acetoacetate, zirconium triethanolamine, acetylacetonate zirconium butoxide, zirconium acetate zirconium butoxide, zirconium acetate, zirconium oxalate, zirconium lactate, zirconium phosphonate, zirconium octanate, Examples thereof include zirconium naphthenate, zirconium laurate, zirconium stearate, zirconium isostearate, zirconium methacrylate butoxide, stearate zirconium butoxide, and isosterate zirconium butoxide.

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, Polyhydroxy Titanium Steerate and the like.

Examples of the aluminum chelate compound include aluminum isopropylate, monobutoxyaluminum diisopropyrate, aluminum butyrate, diethylacetacetate aluminum diisopropirate, aluminum tris (ethylacetacetate) and the like.

These additives may be used alone or as a mixture or polycondensate of multiple 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 for suppressing moire images. It should be adjusted to.
Resin particles or 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. Further, the surface of the undercoat layer may be polished to adjust the surface roughness. Examples of the polishing method include buffing, sandblasting, 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 in which the above components are added to a solvent is formed, and the coating film is dried. Then, if necessary, heat it.

As the solvent for preparing the coating liquid for forming the undercoat layer, known organic solvents such as alcohol-based solvent, aromatic hydrocarbon solvent, halogenated hydrocarbon solvent, ketone-based solvent, ketone alcohol-based solvent, and ether-based solvent are used. Examples thereof include solvents and ester-based solvents.
Specific examples of these solvents include methanol, ethanol, n-propanol, iso-propanol, n-butanol, benzyl alcohol, methyl cellsolve, ethyl cell solution, acetone, methyl ethyl ketone, cyclohexanone, methyl acetate, ethyl acetate, and the like. Examples thereof include ordinary organic solvents such as n-butyl acetate, dioxane, tetrahydrofuran, methylene chloride, chloroform, chlorobenzene and toluene.

Examples of the method for 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 vibrating 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 the undercoat layer onto the 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. Ordinary methods such as.

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

(Mesosphere)
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 (for example, polyvinyl butyral), polyvinyl alcohol resin, polyvinyl acetal resin, casein resin, polyamide resin, cellulose resin, gelatin, polyurethane resin, polyester resin, methacrylic resin, and acrylic resin. Examples thereof include 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.
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 polycondensate of a plurality of compounds.

Among these, 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 an intermediate layer forming coating solution in which the above components are added to a solvent is formed, and the coating film is dried and required. It is performed by heating according to the above.
As a coating method for forming the intermediate layer, ordinary methods 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 are used.

The film thickness of the intermediate layer is preferably set in the range of 0.1 μm or more and 3 μm or less. The intermediate layer may be used as the undercoat layer.

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

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

Among these, in order to correspond to 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 generating material. Specifically, for example, hydroxygallium phthalocyanine disclosed in JP-A-5-263007, JP-A-5-279591, etc .; chlorogallium phthalocyanine disclosed in JP-A-5-98181, etc .; JP-A-5. Dichlorostinphthalocyanine disclosed in JP-A-140472, JP-A-5-140473, etc .; titanylphthalocyanine disclosed in JP-A-4-1809873, etc. is more preferable.

On the other hand, in order to support laser exposure in the near-ultraviolet region, as a charge generating material, a fused ring aromatic pigment such as dibromoanthanthrone; a thioindigo pigment; a porphyrazine compound; zinc oxide; a tricyclic selenium; Bisazo pigments and the like disclosed in JP-A-2004-78147 and JP-A-2005-181992 are preferable.

The above charge generating material may also be used when using a non-interfering light source such as an LED or an organic EL image array having a center wavelength of light emission of 450 nm or more and 780 nm or less, but from the viewpoint of resolution, the photosensitive layer is 20 μm or less. When used in a thin film, the electric field strength in the photosensitive layer becomes high, and a decrease in charge due to charge injection from the substrate, so-called black spots, is likely to occur. This becomes remarkable when a charge-generating material such as a trigonal selenium or a phthalocyanine pigment that easily generates a dark current is used in a p-type semiconductor.

On the other hand, when an n-type semiconductor such as a fused ring aromatic pigment, a perylene pigment, or an azo pigment is used as the charge generating material, dark current is unlikely to be generated, and even a thin film can suppress image defects called black spots. .. Examples of the n-type charge generating material include compounds (CG-1) to (CG-27) described in paragraphs [0288] to [0291] of JP2012-1552282. It is not limited.
The n-type is determined by using the normally used time-of-flight method, and is determined by the polarity of the flowing light current, and the n-type is one in which electrons are more easily flowed as carriers than holes.

The binder resin used for the charge generation layer is selected from a wide range of insulating resins, and the binder resin is from organic photoconductive polymers such as poly-N-vinylcarbazole, polyvinylanthracene, polyvinylpyrene, and polysilane. You may choose.
Examples of the binder resin include polyvinyl butyral resin, polyarylate resin (hypercondensate of bisphenol and aromatic divalent carboxylic acid, etc.), polycarbonate resin, polyester resin, phenoxy resin, vinyl chloride-vinyl acetate copolymer, and the like. Examples thereof include polyamide resin, acrylic resin, polyacrylamide resin, polyvinylpyridine resin, cellulose resin, urethane resin, epoxy resin, casein, polyvinyl alcohol resin, polyvinylpyrrolidone resin and the like. Here, "insulating property" means that the volume resistivity is 10 ¹³ Ωcm or more.
These binder resins are used alone or in admixture of two or more.

The blending ratio of the charge generating material and the binder resin is preferably in the range of 10: 1 to 1:10 in terms of mass ratio.

The charge generation layer may also contain other well-known additives.

The formation of the charge generation layer is not particularly limited, and a well-known formation method is used. For example, a coating film of a coating liquid for forming a charge generation layer in which the above components are added to a solvent is formed, and the coating film is dried. Then, if necessary, heat it. 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 condensed ring aromatic pigment or a perylene pigment is used as the charge generation material.

Solvents for preparing the coating liquid for forming the charge generation layer include methanol, ethanol, n-propanol, n-butanol, benzyl alcohol, methyl cellsolve, ethyl cell solution, acetone, methyl ethyl ketone, cyclohexanone, methyl acetate, n acetate. -Butyl, dioxane, tetrahydrofuran, methylene chloride, chloroform, chlorobenzene, toluene and the like can be mentioned. These solvents may be used alone or in admixture of two or more.

As a method of dispersing particles (for example, a charge generating material) in a coating liquid for forming a charge generating layer, for example, a media disperser such as a ball mill, a vibrating ball mill, an attritor, a sand mill, a horizontal sand mill, or a stirring or ultrasonic disperser , Roll mills, high pressure homogenizers and other medialess dispersers are used. Examples of the high-pressure homogenizer include a collision method in which a dispersion liquid is dispersed by liquid-liquid collision or a liquid-wall collision in a high-pressure state, and a penetration method in which a dispersion liquid is dispersed by penetrating a fine flow path in a high-pressure state.
At the time of this dispersion, it is effective to set the average particle size of the charge generating material in the coating liquid for forming the charge generating layer to 0.5 μm or less, preferably 0.3 μm or less, and more preferably 0.15 μm or less. ..

As a method of applying the coating liquid for forming the charge generation layer on the undercoat layer (or on the intermediate layer), for example, a blade coating method, a wire bar coating method, a spray coating method, a dipping coating method, a bead coating method, and an air knife coating method. Examples include the usual method such as a method and a curtain coating method.

The film thickness of the charge generation layer is preferably set within the range of 0.1 μm or more and 5.0 μm or less, more preferably 0.2 μm or more and 2.0 μm or less.

(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 polymer charge transport material.

Examples of the charge transport material include quinone compounds such as p-benzoquinone, chloranyl, bromanyl and anthraquinone; tetracyanoquinodimethane compounds; fluorenone compounds such as 2,4,7-trinitrofluorenone; xanthone compounds; benzophenone compounds. Examples include cyanovinyl compounds; electron transporting compounds such as ethylene compounds. Examples of the charge transporting material include hole transporting compounds such as triarylamine-based compounds, benzidine-based compounds, arylalkane-based compounds, aryl-substituted ethylene-based compounds, stillben-based compounds, anthracene-based compounds, and hydrazone-based compounds. These charge transporting materials may be used alone or in combination of two or more, but are not limited thereto.

Among these compounds, triarylamine-based compounds and benzidine-based compounds are mentioned as preferable charge transporting materials from the viewpoint of charge mobility. Among them, as the triarylamine-based compound, a charge-transporting material represented by the following formula (CT1), which is an example of a triarylamine-based compound (hereinafter, also referred to as “butadiene-based charge-transporting material), is preferable. As the compound, a charge transport material represented by the following general formula (CT2) (hereinafter, also referred to as “benzidine-based charge transport material”) is preferable.

Butadiene-based charge transport material The butadiene-based charge transport material will be described below. The butadiene-based charge transport material is represented by the following general formula (CT1).

In the general formula (CT1), ^RC11 , ^RC12 , ^RC13 , ^RC14 , ^RC15 , and ^RC16 are each independently a hydrogen atom, a halogen atom, an alkyl group having 1 to 20 carbon atoms, and 1 carbon atom. It represents an alkoxy group of 20 or more or an aryl group having 6 or more and 30 or less 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 ^(CT1), as the ^{R C11, R C12, R C13} , R C14, R C15, and halogen atom ^{which R C16} represents 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 ^{(CT1), R C11, R} C12, R C13, R C14, R C15, and the alkyl ^{group R C16} represents 1 to 20 carbon atoms (preferably 1 to 6, more preferably 1 (4 or less) linear or branched alkyl groups can be mentioned.
Specific examples of the linear alkyl group include methyl group, ethyl group, n-propyl group, n-butyl group, n-pentyl group, n-hexyl group, n-heptyl group, n-octyl group and 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 thereof include a nonadecil 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 group, isoundecyl group, sec-undecyl group, tert-undecyl group, neoundecyl group, isododecyl group, sec-dodecyl group, tert-dodecyl group, neododecyl group, isotridecyl group, sec-tridecyl group, tert-tridecyl group, neotridecyl group , Isotetradecyl group, sec-tetradecyl group, tert-tetradecyl group, neotetradecyl group, 1-isobutyl-4-ethyloctyl group, isopentadecyl group, sec-pentadecyl group, tert-pentadecyl group, neopentadecyl 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, neo-octadecyl group, isononadecyl group, sec-nonadecil group, tert-nonadecil group, neononadecil group, 1-methyloctyl group, isoicocil group, sec-icocil group, tert-icocil group, neoicocil group, etc. Can be mentioned.
Among these, as the alkyl group, a lower alkyl group such as a methyl group, an ethyl group and an isopropyl group is preferable.

In the general formula ^{(CT1), R C11, R} C12, R C13, R C14, R C15, and the alkoxy group represented by ^{R C16,} 1 to 20 carbon atoms (preferably 1 to 6, more preferably 1 4 or less) linear or branched alkoxy groups can be mentioned.
Specific examples of the linear alkoxy group include a methoxy group, an ethoxy group, an n-propoxy group, an n-butoxy group, an n-pentyloxy group, an n-hexyloxy group, an n-heptyloxy group, and an n-octyloxy group. 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-nonadesyloxy group, an n-icosyloxy group and the like.
Specific examples of the branched alkoxy group include isopropoxy group, isobutoxy group, sec-butoxy group, tert-butoxy group, isopentyloxy group, neopentyloxy group, tert-pentyloxy group, isohexyloxy group, 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 , Isododecyloxy group, sec-dodecyloxy group, tert-dodecyloxy group, neododecyloxy group, isotridecyloxy group, sec-tridecyloxy group, tert-tridecyloxy group, neotridecyloxy group, iso Tetradecyloxy group, sec-tetradecyloxy group, tert-tetradecyloxy group, neotetradecyloxy group, 1-isobutyl-4-ethyloctyloxy group, isopentadecyloxy group, sec-pentadecyloxy group, tert -Pentadecyloxy 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, Examples thereof include sec-nonadesyloxy group, tert-nonadesyloxy group, neononadesyloxy group, 1-methyloctyloxy group, isoicosyloxy group, sec-icosyloxy group, tert-icosyloxy group, neoicosyloxy group and the like.
Among these, the methoxy group is preferable as the alkoxy group.

In the general formula ^{(CT1), R C11, R} C12, R C13, R C14, R C15, and the aryl group represented by ^{R C16,} 6 to 30 carbon atoms (preferably 6 to 20, more preferably 6 16 or less) aryl groups can be mentioned.
Specific examples of the aryl group include a phenyl group, a naphthyl group, a phenanthryl group, and a biphenylyl group.
Among these, as the aryl group, a phenyl group and a naphthyl group are preferable.

Incidentally, in the general formula ^{(CT1), R C11, R} C12, R C13, R C14, R C15, and each of ^{the substituents R C16} represents also includes groups having a substituent. Examples of this substituent include the above-exemplified atoms and groups (for example, halogen atom, alkyl group, alkoxy group, aryl group, etc.).

In the general formula ^{(CT1), R C11, R} C12, R C13, R C14, R C15, and two substituents together (e.g. ^{R C11} and ^{R C12} between adjacent of ^{R C16, R C13} and ^{R C14} s, R ^In the hydrocarbon ring structure in which ( ^C15 and ^RC16 ) are linked, the groups that link 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, 2,2'-methylene group is preferable.
Here, specific examples of the hydrocarbon ring structure include a cycloalkane structure, a cycloalkene structure, and a cycloalkane polyene structure.

In the general formula (CT1), n and m are preferably 1.

In the general formula (CT1), a high sensitive layer (charge transport layer) of the charge transport ability of formation of ^{point, R C11, R C12, R} C13, R C14, R C15, and ^{R C16} is a hydrogen atom, 1 or more carbon atoms 20 an alkyl group, or represents a number 1 to 20 alkoxy group carbon, m and n are preferable to represent the 1 or ^{2, R C11, R C12,} R C13, R C14, R C15, and R It is more preferable that ^C16 represents a hydrogen atom and m and n represent 1.
That is, the butadiene-based charge transport material (CT1) is more preferably a charge transport material (exemplified compound (CT1-3)) represented by the following structural formula (CT1A).

Specific examples of the butadiene-based charge transport material (CT1) are shown below, but the present invention is not limited to this. In addition, the following example compound number is referred to as an example compound (CT1-number) below. Specifically, for example, the exemplary compound 15 is hereinafter referred to as “exemplified compound (CT1-15)”.

The abbreviations in the above-exemplified compounds have the following meanings. The number attached before the substituent indicates the substitution position with respect to the benzene ring.
-CH ₃ : Methyl group-OCH ₃ : Methoxy group

As the butadiene-based charge transport material (CT1), one type may be used alone, or two or more types may be used in combination.

-Benzidine-based charge transport material As the benzidine-based compound, a benzidine-based charge transport material (CT2) represented by the following general formula (CT2) is preferably mentioned from the viewpoint of charge mobility.
In particular, from the viewpoint of charge mobility, it is preferable to use a butadiene-based charge transport material (CT1) and a benzidine-based charge transport material (CT2) together as the charge transport material. The mass ratio (content of butadiene-based charge transport material (CT1) / content of benzidine-based charge transport material (CT2)) when the butadiene-based charge transport material (CT1) and the benzidine-based charge transport material (CT2) are used in combination. The amount) is preferably 1/9 or more and 5/5 or less, and more preferably 1/9 or more and 4/6 or less from the viewpoint of charge transporting ability.

Hereinafter, the benzidine-based charge transport material will be described. The benzidine-based charge transport material is represented by the following general formula (CT2).

In the general formula (CT2), ^RC21 , ^RC22 , and ^RC23 each independently represent a hydrogen atom, a halogen atom, a hydroxyl group, a formyl group, an alkyl group, an alkoxy group, or an aryl group.

In the general formula ^(CT2), as the R ^{C21, R C22,} and halogen atom ^{which R C23} represents 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 ^(CT2), the alkyl group represented by R ^{C21, R C22,} and ^{R C23,} 1 to 10 carbon atoms (preferably 1 to 6, more preferably 1 to 4) linear or Examples include branched alkyl groups.
Specifically, as a linear alkyl group, 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, an n-octyl group, an n- Examples thereof 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- A decyl group and the like can be mentioned.
Among these, as the alkyl group, a lower alkyl group such as a methyl group, an ethyl group and an isopropyl group is preferable.

In the general formula ^(CT2), the alkoxy group represented by R ^{C21, R C22,} and ^{R C23,} 1 to 10 carbon atoms (preferably 1 to 6, more preferably 1 to 4) linear or Examples include branched alkoxy groups.
Specific examples of the linear alkoxy group include a methoxy group, an ethoxy group, an n-propoxy group, an n-butoxy group, an n-pentyloxy group, an n-hexyloxy group, an n-heptyloxy group, and an n-octyloxy group. Examples include a group, an n-nonyloxy group, an n-decyloxy group and the like.
Specifically, as the branched alkoxy group, 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, 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 thereof include sec-nonyloxy group, tert-nonyloxy group, isodecyloxy group, sec-decyloxy group, tert-decyloxy group and the like.
Among these, the methoxy group is preferable as the alkoxy group.

In the general formula ^(CT2), the aryl group represented by R ^{C21, R C22,} and ^{R C23,} having 6 to 10 carbon atoms (preferably 6 to 9, more preferably 6 to 8) and an aryl group Be done. 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.

Incidentally, in the general formula ^{(CT2), R C21, R} C22, and each of ^{the substituents R C23} represents also includes groups having a substituent. Examples of this substituent include the above-exemplified atoms and groups (for example, halogen atom, alkyl group, alkoxy group, aryl group, etc.).

In the general formula (CT2), ^RC21 , ^RC22 , and ^RC23 each independently have a hydrogen atom or one or more carbon atoms, particularly from the viewpoint of forming a photosensitive layer (charge transport layer) having high charge transport capacity. preferably represents an 10 an alkyl ^group, R ^{C21, R C22,} and ^{R C23} is ^{hydrogen, R C22} is 1 to 10 alkyl group carbon atoms (particularly, methyl group) preferably more may represent ..
Specifically, the benzidine-based charge transport material (CT2) is particularly preferably a charge transport material (exemplified compound (CT2-2)) represented by the following structural formula (CT2A).

Specific examples of the charge transport material represented by the general formula (CT2) are shown below, but the present invention is not limited to this. The following example compound number is hereinafter referred to as the example compound (CT2-number). Specifically, for example, Exemplified Compound 15 is hereinafter referred to as “Exemplary Compound (CT2-15)”.

The abbreviations in the above-exemplified compounds have the following meanings. The number attached before the substituent indicates the substitution position with respect to the benzene ring.
-CH ₃ : Methyl group-C ₂ H ₅ : Ethyl group-OCH ₃ : methoxy group-OC ₂ H ₅ : ethoxy group

As the benzidine-based charge transport material (CT2), one type may be used alone, or two or more types may be used in combination.

As the polymer charge transport material, known materials having charge transport properties such as poly-N-vinylcarbazole and polysilane are used. In particular, polyester-based polymer charge transport materials disclosed in JP-A-8-176293 and JP-A-8-208820 are particularly preferable. The polymer charge transport material may be used alone or in combination with the 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, etc. can be mentioned. Among these, as the binder resin, a polycarbonate resin or a polyarylate resin is preferable. One of these binder resins is used alone or in combination of two or more.
The blending ratio of the charge transport material and the binder resin is preferably 10: 1 to 1: 5 in terms of mass ratio.
-Fluorine-containing resin particles The fluorine-containing resin particles will be described.
Examples of the fluorine-containing resin particles include polytetrafluoroethylene (tetrafluoroethylene resin), trifluoroethylene resin, hexafluoride propylene resin, vinyl fluoride resin, vinylidene fluoride resin, and ethylene difluoride dichloride. It is desirable to select one or more of the particles of the resin and its copolymer. Among these, as the fluorine-containing resin particles, polytetrafluoroethylene particles or vinylidene fluoride resin particles are preferable, and polytetrafluoroethylene particles are particularly preferable.

The number average primary particle size of the fluorine-containing resin particles is preferably 0.05 μm or more and 1 μm or less, and more preferably 0.1 μm or more and 0.5 μm or less.
The number average primary particle size is obtained by obtaining a sample piece from the photosensitive layer (charge transport layer) and observing it with an SEM (scanning electron microscope) at a magnification of 5,000 or more, for example, to obtain fluorine in the primary particle state. The maximum diameter of the resin particles is measured, and this is taken as the average value obtained for 50 particles. A JSM-6700F manufactured by JEOL Ltd. is used as the SEM, and a secondary electron image having an acceleration voltage of 5 kV is observed.

Commercially available products of fluorine-containing resin particles include, for example, Lubron (registered trademark) series (manufactured by Daikin Industries, Ltd.), Teflon (registered trademark) series (manufactured by DuPont), and Dynion (registered trademark) series (Sumitomo 3M Ltd.). ), Etc.

The content of the fluorine-containing resin particles is preferably 5% by mass or more and 20% by mass or less, and more preferably 6% by mass or more and 10% by mass or less, based on the total solid content of the charge transport layer (photosensitive layer).

-Fluorine-containing dispersant Examples of the fluorine-containing dispersant include polymers obtained by homopolymerizing or copolymerizing a polymerizable compound having an alkyl fluoride group (hereinafter, also referred to as "alkyl fluoride group-containing polymer").

Specifically, as the fluorine-containing dispersant, a homopolymer of a (meth) acrylate having an alkyl fluoride group, a (meth) acrylate having an alkyl fluoride group and a monomer having no fluorine atom have a random or block co-weight. Examples include coalescence. The (meth) acrylate means both acrylate and methacrylate.

Examples of the (meth) acrylate having an alkyl fluoride group include 2,2,2-trifluoroethyl (meth) acrylate and 2,2,3,3,3-pentafluoropropyl (meth) acclilate.

Examples of the monomer having no fluorine atom include (meth) acrylate, isobutyl (meth) acrylate, t-butyl (meth) acrylate, isooctyl (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate, and isobornyl. (Meta) acrylate, cyclohexyl (meth) acrylate, 2-methoxyethyl (meth) acrylate, methoxytriethylene glycol (meth) acrylate, 2-ethoxyethyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, benzyl (meth) Acrylate, ethyl carbitol (meth) acrylate, phenoxyethyl (meth) acrylate, 2-hydroxy (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, methoxypolyethylene glycol (meth) acrylate , Methoxypolyethylene glycol (meth) accrylate, phenoxypolyethylene glycol (meth) acrylate, phenoxypolyethylene glycol (meth) acrylate, hydroxyethyl o-phenylphenol (meth) acrylate, o-phenylphenol glycidyl ether (meth) acrylate.

In addition, specific examples of the fluorine-containing dispersant include block or branch polymers disclosed in US Pat. No. 5,637,142, Japanese Patent No. 4251662. Further, specific examples of the fluorine-containing dispersant include a fluorine-based surfactant.

Among these, as the fluorine-containing dispersant, a fluoroalkyl group-containing polymer having a structural unit represented by the following general formula (FA) is preferable, and the structural unit represented by the following general formula (FA) and the following general formula are used. A fluoroalkyl group-containing polymer having a structural unit represented by (FB) is more preferable.

Hereinafter, an alkyl fluoride group-containing polymer having a structural unit represented by the following general formula (FA) and a structural unit represented by the following general formula (FB) will be described.

In the general formulas (FA) and (FB), R ^F1 , R ^F2 , R ^F3 and R ^F4 each independently represent a hydrogen atom or an alkyl group.
X ^F1 represents an alkylene chain, a halogen-substituted alkylene chain, -S-, -O-, -NH-, or a single bond.
Y ^F1 represents an alkylene chain, a halogen-substituted alkylene chain,-(C _fx H _2fx-1 (OH))-or a single bond.
Q ^F1 represents -O- or -NH-.
fl, fm and fn each independently represent an integer of 1 or more.
fp, fq, fr and fs each independently represent an integer greater than or equal to 0 or 1.
ft represents an integer of 1 or more and 7 or less.
fx represents an integer of 1 or more.

In the general formulas (FA) and (FB), as the group representing R ^F1 , R ^F2 , R ^F3 and R ^F4 , a hydrogen atom, a methyl group, an ethyl group, a propyl group and the like are preferable, and a hydrogen atom and a methyl group are more. Preferably, a methyl group is more preferred.

In the general formulas (FA) and (FB), the alkylene chain (unsubstituted alkylene chain, halogen-substituted alkylene chain) representing X ^F1 and Y ^F1 is a linear or branched alkylene chain having 1 to 10 carbon atoms. Is preferable.
It is preferable that _{fx in} − (C _fx H _2fx-1 (OH)) − representing Y ^F1 represents an integer of 1 or more and 10 or less.
It is preferable that fp, fq, fr and fs independently represent 0 or an integer of 1 or more and 10 or less, respectively.
The fn is preferably 1 or more and 60 or less, for example.

Here, in the fluorine-containing dispersant, the ratio of the structural unit represented by the general formula (FA) to the structural unit represented by the general formula (FB), that is, fl: fm is from 10:90 to 99: 1. It is preferably in the range, more preferably in the range of 10:90 to 95: 5, even more preferably in the range of 50:50 to 95: 5, from 30:70 to 70:30. The range is particularly preferred.

The fluorine-containing dispersant may further have a structural unit represented by the general formula (FC) in addition to the structural unit represented by the general formula (FA) and the structural unit represented by the general formula (FB). The content ratio of the structural units represented by the general formula (FC) is the total of the structural units represented by the general formulas (FA) and (FB), that is, the ratio to fl + fm ((fl + fm): fz) from 100: 0. The range is preferably from 7: 3, more preferably from 99: 1 to 70:30, even more preferably from 95: 5 to 70:30, from 90:10. The range up to 70:30 is more preferable, and the range from 90:10 to 60:40 is particularly preferable.

In the general formula (FC), ^RF5 and ^RF6 each independently represent a hydrogen atom or an alkyl group. fz represents an integer of 1 or more.

In the general formula (FC), as the group represented by R ^F5, and R ^F6, a hydrogen atom, a methyl group, an ethyl group, a propyl group, more preferably a hydrogen atom, more preferably a methyl group, more preferably a methyl group.

Commercially available fluorine-containing dispersants include, for example, GF300, GF400 (manufactured by Toagosei Co., Ltd.), Surflon (registered trademark) series (manufactured by AGC Seimi Chemical Co., Ltd.), Futergent series (manufactured by Neos Co., Ltd.), and PF series (manufactured by Kitamura Chemical Co., Ltd.) (Manufactured by the company), Megafuck (registered trademark) series (manufactured by DIC), FC series (manufactured by 3M) and the like.

The weight average molecular weight Mw of the fluorine-containing dispersant is preferably 20,000 or more and 200,000 or less, more preferably 25,000 or more and 200,000 or less, further preferably 50,000 or more and 200,000 or less, and further preferably 80,000 or more and 150,000 or less. It is preferable, and 80,000 or more and 100,000 or less are particularly preferable.

The molecular weight distribution Mw / Mn (weight average molecular weight Mw / number average molecular weight Mn) of the fluorine-containing dispersant is preferably 1.5 or more and 5.0 or less, more preferably 1.5 or more and 3.5 or less, and 1.5 or more. 3.0 or less is more preferable.
In order to make the molecular weight distribution Mw / Mn within the above range, for example, the fluorine-containing dispersant obtained by polymerization is reprecipitated and purified. For example, the molecular weight distribution Mw / Mn of the obtained fluorine-containing dispersant can be within the above range by adding a poor solvent to the fluorine-containing dispersant solution dissolved in a good solvent and recovering the precipitate product.

The weight average molecular weight and the number average molecular weight of the fluorine-containing dispersant are values measured by gel permeation chromatography (GPC). The molecular weight measurement by GPC is performed, for example, by using Tosoh's GPC / HLC-8120 as a measuring device and Tosoh's column / TSKgel GMHHR-M + TSKgel GMHHR-M (7.8 mm I.D. 30 cm) in a chloroform solvent. It is calculated from this measurement result using a molecular weight calibration curve prepared from a monodisperse polystyrene standard sample.

Fluorine-containing dispersant, in the infrared absorption spectrum, to the peak area in the range of wave number 1673cm ^-1 or higher wavenumber 1779cm ^-1, a peak area ratio in the range of wave numbers of 1020 cm ^-1 or more wavenumber 1308cm ^-1 is 2.7 or more 4. It may be 8 or less.

Peak area ratio (peak area in the range of wave numbers of 1020 cm ^-1 or more wavenumber 1308cm ^-1 in the range of peak area / wavenumber 1673cm ^-1 or higher wavenumber 1779cm ^-1), from the viewpoint of the local cleaning of suppressing reduction, 2.8 More than 4.8 or less is preferable, and 3.5 or more and 4.8 or less is more preferable.

The infrared absorption spectrum of the fluorine-containing dispersant is measured by the following method.
First, the fluorine-containing dispersant to be measured is made into a powder or a film to prepare a measurement sample for the ATR method (total reflection measurement method). Then, the wave number of the measurement sample is measured by an infrared spectrophotometer (manufactured by JASCO Corporation: FT / IR-6100, ATR unit, with window material ZnSe) under the conditions of 64 integration times and a resolution of 4 cm ^-1. obtain an infrared absorption spectrum carried out after ATR correction of the measurement of the 650cm ^-1 more than 4000cm ^-1 or less.
Then, the peak area in the range of wave number 1673 cm ^-1 or more and wave number 1779 cm ^-1 is determined as a carbonyl group in the fluorine-containing dispersant.
Similarly, the peak area in the range of wave number 1020 cm ^-1 or more and wave number 1308 cm ^-1 is determined as the sum of the CF group and the COC group of the fluorine-containing dispersant.

When measuring the infrared absorption spectrum of the fluorine-containing dispersant from the charge transport layer containing the fluorine-containing dispersant (when the photosensitive layer is a single-layer type photosensitive layer, the single-layer type photosensitive layer; the same applies hereinafter). , The fluorine-containing dispersant, which is a measurement sample, is collected as follows.
The charge transport layer is dissolved in a soluble solvent such as tetrahydrofuran, and the fluororesin particles are filtered through a 0.1 μm mesh filter. Next, the fluororesin particles obtained by filtration are subjected to aromatic hydrocarbons such as toluene and xylene, halogen solvents such as fluorocarbon, perfluorocarbon, hydrochlorofluorocarbon, methylene chloride and chloroform, ethyl acetate, butyl acetate and the like. After heating at 100 ° C or lower in a ketone solvent such as ester solvent, acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclopentanone, etc., or a mixed solvent of two or more kinds, the mixture is filtered, dried, and adsorbed on the surface of fluororesin particles. Elute and collect the fluorocarbon-containing dispersant.

Examples of the fluorine-containing dispersant having the peak area ratio include a polymer obtained by copolymerizing at least a polymerizable compound having an alkyl fluoride group and a polymerizable compound having no alkyl fluoride group and having an ester group. Can be mentioned. Then, by adjusting the amount ratio of these two kinds of polymerizable compounds, a fluorine-containing dispersant having a peak area ratio can be obtained.

The abundance Xf of the dispersant having the fluorine atom with respect to the fluororesin particles on the surface side and the dispersion having the fluorine atom with respect to the fluororesin particles on the conductive substrate side as measured by X-ray photoelectron spectroscopy (XPS). When the abundance amount of the agent is Xr, the relationship of Xf / Xr ≧ 1.04 is satisfied. Xf / Xr is preferably Xf / Xr ≧ 1.1, and more preferably Xf / Xr ≧ 1.2. The upper limit of Xf / Xr is not particularly limited, and may be, for example, 3.5 ≧ Xf / Xr.

The abundance Xf of the dispersant having a fluorine atom with respect to the fluororesin particles on the surface side, which is measured by X-ray photoelectron spectroscopy (XPS), is preferably 0.50% or more and 9.80% or less, and is 0. It is more preferably .80% or more and 7.50% or less, further preferably 2.00% or more and 7.50% or less, and further preferably 2.10% or more and 4.50% or less. It is particularly preferable that it is 2.10% or more and 2.50% or less. Further, the abundance Xr of the dispersant having a fluorine atom with respect to the fluororesin particles on the conductive substrate side is preferably 0.40% or more and 3.60% or more, and 0.60% or more and 3.55% or more. It is more preferably 1.40% or more and 2.80% or less, and particularly preferably 1.80% or more and 2.20% or less.

With respect to the surface side of the charge transport layer and the conductive substrate side of the charge transport layer, Xf and Xr are obtained as follows.
First, the charge transport layer is peeled off from the photoconductor to be measured, and a sample for measurement is prepared. Next, the X-ray photoelectron spectrometer (XPS: JEOL Ltd.) was used for each of the surface of the measurement sample on the conductive substrate side and the surface (front surface) opposite to the conductive substrate side. Measured by JPS-9010MX). Next, from the obtained measurement results, the peak area derived from the fluororesin particles is defined as the abundance of the fluororesin particles, and the peak area derived from the fluorine-containing dispersant is defined as the abundance of the fluororesin dispersant. Next, the abundance Xf (%) of the fluorine-containing dispersant with respect to the fluororesin particles on the conductive substrate side is obtained from the ratio of the peak area derived from the fluororesin particles and the peak area derived from the fluorine-containing dispersant. Similarly, the abundance Xr (%) of the fluorine-containing dispersant with respect to the fluororesin particles on the surface (front surface) side is determined. Then, the abundance ratio Xf / Xr is calculated from the obtained Xf and Xr.

The charge transport layer may also contain other well-known additives.

-Formation of charge transport layer-
The formation of the charge transport layer is not particularly limited, and a well-known forming method is used. For example, a coating film of a coating liquid for forming a charge transport layer in which the above components are added to a solvent is formed, and the coating film is dried. , By heating as needed.

Solvents for preparing the coating liquid for forming the charge transport layer include aromatic hydrocarbons such as benzene, toluene, xylene and chlorobenzene; ketones such as acetone and 2-butanone; methylene chloride, chloroform, ethylene chloride and the like. Halogenated aliphatic hydrocarbons; ordinary organic solvents such as cyclic or linear ethers such as tetrahydrofuran and ethyl ether can be mentioned. These solvents are used alone or in combination of two or more.

The abundance Xf of the dispersant having fluorine atoms with respect to the fluororesin particles on the surface side of the photosensitive layer is made higher than the abundance Xr of the dispersant having fluorine atoms with respect to the fluororesin particles on the conductive substrate side of the photosensitive layer, and Xf / Examples of a suitable method for satisfying Xr ≧ 1.04 include the following methods.

First, a dispersion liquid in which the fluororesin particles and the fluorine-containing dispersant are dispersed with an organic solvent having a relatively low polarity (for example, toluene, P'= 2.4) is prepared (dispersion liquid A). Next, a coating liquid for forming a charge transport layer is prepared by mixing a binder resin, a charge transport material, and the like and dispersing them using a relatively highly polar organic solvent (for example, tetrahydrofuran, P'= 4.0). (Dispersion liquid B). Next, the dispersion liquid A and the dispersion liquid B prepared above are mixed. Next, an organic solvent having a higher polarity than the solvent used for adjusting the dispersion B (for example, methyl ethyl ketone, P'= 4.7) is added to adjust the polarity of the coating solution for forming the charge transport layer. .. It is considered that the fluorine-containing dispersant adhering to the fluororesin particles is eliminated by adjusting the polarity of the coating liquid for forming the charge transport layer. That is, by forming the charge transport layer using the coating liquid for forming the charge transport layer whose polarity is adjusted to the extent that the fluorine-containing dispersant adhering to the fluororesin particles is desorbed, the charge transport layer is formed on the surface side of the charge transport layer. Since the fluorine-containing dispersant moves, a charge transport layer satisfying Xf / Xr ≧ 1.04 can be obtained. Not limited to this, if the polarity of the coating liquid for forming the charge transport layer can be adjusted to the extent that the fluorine-containing dispersant adhering to the fluororesin particles is desorbed, a method for adjusting the coating liquid for forming the charge transport layer. , The type of solvent is not limited.

The content of the fluorine-containing dispersant in the entire charge transport layer (entire photosensitive layer) is preferably 5% by mass or more and 40% by mass or less, and 5% by mass or more and 35% by mass or less with respect to the fluororesin particles. More preferably, it is more preferably 6% by mass or more and 35% by mass or less. When the content of the fluorine-containing dispersant is in the above range, the decrease in the life of the photoconductor is further suppressed and the generation of ghosts is further suppressed. The fluorine-containing dispersant may be used alone or in combination of two or more.

When applying the coating liquid for forming a charge transport layer on the charge generating layer, the coating method includes 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. Examples include a normal method such as a coating method.

(Protective layer)
The protective layer is provided on the photosensitive layer as needed. The protective layer is provided, for example, for the purpose of preventing a chemical change of the photosensitive layer during charging and further improving the mechanical strength of the photosensitive layer.
Therefore, as the protective layer, it is preferable to apply a layer composed of a cured film (crosslinked film). Examples of these layers include the layers shown in 1) or 2) below.

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 cross-linking of the reactive group-containing charge-transporting material). Layer including body)
2) A layer composed of a cured film of a composition containing a non-reactive charge transport material and a reactive group-containing non-charge transport material having a reactive group and having no charge transport skeleton (that is,). A layer containing a non-reactive charge transport material and a polymer or crosslinked product of the reactive group-containing non-charge transport material)

The reactive groups of the reactive group-containing charge transport material include chain polymerizable groups, epoxy groups, -OH, -OR [where R indicates an alkyl group], -NH ₂ , -SH, -COOH, -SiR. ^{_{Q1 3-Qn (oR Q2)}} Qn [ ^{where, R Q1} represents a hydrogen atom, an alkyl group, or a substituted or unsubstituted aryl ^{group, R Q2} is a hydrogen atom, an alkyl group, trialkylsilyl group. Qn represents an integer of 1-3] and other well-known reactive groups.

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

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 the electrophotographic photosensitive member, and is, for example, a triarylamine-based compound, a benzidine-based compound, a hydrazone-based compound, or the like. A skeleton derived from a nitrogen-containing hole-transporting compound of the above, and has a structure conjugated with a nitrogen atom. Among these, the triarylamine skeleton is preferable.

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

The protective layer may also contain other well-known additives.

As the solvent for preparing the coating liquid for forming the 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 , Ether-based solvent such as dioxane; cellosolve-based solvent such as ethylene glycol monomethyl ether; alcohol-based solvent such as isopropyl alcohol and butanol. These solvents are used alone or in combination of two or more.
The coating liquid for forming the protective layer may be a solvent-free coating liquid.

As a method of applying the coating liquid for forming a protective layer on a photosensitive layer (for example, a charge transport layer), a dipping 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 are used. Ordinary methods such as law can be mentioned.

The film thickness of the protective layer is preferably set within the range of 1 μm or more and 20 μm or less, more preferably 2 μm or more and 10 μm or less.

(Single-layer photosensitive layer)
The single-layer photosensitive layer (charge generation / charge transport layer) is a layer containing, for example, a charge generation material, a charge transport material, and, if necessary, a binder resin and other well-known additives. These materials are the same as the materials described in the charge generation layer and the charge transport layer.
The content of the charge generating material in the single-layer photosensitive layer is preferably 0.1% by mass or more and 10% by mass or less, preferably 0.8% by mass or more and 5% by mass or less, based on the total solid content. .. Further, the content of the charge transport material in the single-layer photosensitive layer is preferably 5% by mass or more and 50% by mass or less with respect to the total solid content.
The method for forming the single-layer photosensitive layer is the same as the method for forming the charge generation layer and the charge transport layer.
The film thickness of the single-layer photosensitive layer is, for example, preferably 5 μm or more and 50 μm or less, preferably 10 μm or more and 40 μm or less.

When the photosensitive layer is a single-layer type photosensitive layer, the abundance Xf of the fluorine-containing dispersant with respect to the fluororesin particles on the photosensitive layer conductive substrate side and the fluorine-containing dispersion with respect to the fluororesin particles on the surface (front surface) side. The abundance Xr of the agent may be measured in the same manner as in the procedure described for the charge transport layer described above. That is, the single-layer type photosensitive layer is peeled off from the photoconductor to be measured, and the measurement is performed in the same procedure as described above.
Further, even when the photosensitive layer is a single-layer type photosensitive layer, in order to satisfy Xf / Xr ≧ 1.04, adjustment may be performed in the same manner as the adjustment method described in the charge transport layer described above, that is, that is, For example, a dispersion liquid A is prepared, a dispersion liquid B in which a binder resin, a charge generating material, a charge transport material, and the like are mixed is prepared, and after mixing the dispersion liquid A and the dispersion liquid B, a single-layer type photosensitive layer is formed. The polarity of the coating liquid for use may be adjusted.

[Image forming device (and process cartridge)]
The image forming apparatus according to the present embodiment includes an electrophotographic photosensitive member, a charging means for charging the surface of the electrophotographic photosensitive member, and an electrostatic latent image forming which forms an electrostatic latent image on the surface of the charged electrophotographic photosensitive member. Means, a developing means for developing an electrostatic latent image formed on the surface of an electrophotographic photosensitive member with a developer containing toner to form a toner image, and a transfer means for transferring the toner image to the surface of a recording medium. To be equipped. Then, as the electrophotographic photosensitive member, the electrophotographic photosensitive member according to the present embodiment is applied.

The image forming apparatus according to the present embodiment is an apparatus provided with fixing means for fixing the toner image transferred to the surface of the recording medium; direct transfer for directly transferring the toner image formed on the surface of the electrophotographic photosensitive member to the recording medium. Device of the method; Intermediate transfer in which the toner image formed on the surface of the electrophotographic photosensitive member is primarily transferred to the surface of the intermediate transfer body, and the toner image transferred to the surface of the intermediate transfer body is secondarily transferred to the surface of the recording medium. A device equipped with a cleaning means for cleaning the surface of the electrophotographic photosensitive member after the transfer of the toner image and before charging; the surface of the electrophotographic photosensitive member is irradiated with xerographic light after the transfer of the toner image and before charging. A device provided with a static elimination means for eliminating static electricity; a well-known image forming apparatus such as a device provided with 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 apparatus, the transfer means is, for example, a primary transfer body in which a toner image is transferred to the surface and a primary transfer of a toner image formed on the surface of an electrophotographic photosensitive member to the surface of the intermediate transfer body. A configuration having a transfer means and a secondary transfer means for secondary transfer of the toner image transferred to 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 (development method 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) attached to and detached from the image forming apparatus. As the process cartridge, for example, a process cartridge including the electrophotographic photosensitive member according to the present embodiment is preferably used. In addition to the electrophotographic photosensitive member, the process cartridge may include at least one selected from the group consisting of, for example, charging means, electrostatic latent image forming means, developing means, and transfer means.

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

FIG. 2 is a schematic configuration diagram showing an example of an image forming apparatus according to the present embodiment.
As shown in FIG. 2, the image forming apparatus 100 according to the present embodiment includes a process cartridge 300 including an electrophotographic photosensitive member 7, an exposure apparatus 9 (an example of an electrostatic latent image forming means), and a transfer apparatus 40 (primary). A transfer device) and an intermediate transfer body 50 are provided. In the image forming apparatus 100, the exposure apparatus 9 is arranged at a position where the electrophotographic photosensitive member 7 can be exposed through the opening of the process cartridge 300, and the transfer apparatus 40 is arranged through the intermediate transfer body 50 to expose the electrophotographic photosensitive member 7. The intermediate transfer member 50 is arranged at a position facing the seventh, and a part of the intermediate transfer member 50 is arranged in contact with the electrophotographic photosensitive member 7. Although not shown, it also has a secondary transfer device that transfers 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 the transfer means.

The process cartridge 300 in FIG. 2 has an electrophotographic photosensitive member 7, a charging device 8 (an example of charging means), a developing device 11 (an example of developing means), and a cleaning device 13 (an example of cleaning means) integrated 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 come into contact with the surface of the electrophotographic photosensitive member 7. The cleaning member may be a conductive or insulating fibrous member instead of the mode of the cleaning blade 131, and may be used alone or in combination with the cleaning blade 131.

In addition, in FIG. 2, as an image forming apparatus, a fibrous member 132 (roll shape) that supplies the lubricating material 14 to the surface of the electrophotographic photosensitive member 7 and a fibrous member 133 (flat brush shape) that assists cleaning are shown. Examples 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 charging device using a conductive or semi-conductive charging roller, a charging brush, a charging film, a charging rubber blade, a charging tube, or the like is used. Further, a non-contact type roller charger, a scorotron charger using corona discharge, a corotron charger, or the like, which is known per se, is also used.

-Exposure device-
Examples of the exposure apparatus 9 include an optical system device that exposes light such as a semiconductor laser beam, an LED light, and a liquid crystal shutter light on the surface of the electrophotographic photosensitive member 7 in a predetermined image pattern. The wavelength of the light source is within the spectral sensitivity region of the electrophotographic photosensitive member. As the wavelength of the semiconductor laser, the near infrared having an oscillation wavelength in the vicinity of 780 nm is the mainstream. However, the wavelength is not limited to this, and a laser having an oscillation wavelength in the 600 nm range or a laser having an oscillation wavelength of 400 nm or more and 450 nm or less may be used as a blue laser. Further, a surface emitting type laser light source capable of outputting a multi-beam is also effective for forming a color image.

-Developer-
Examples of the developing device 11 include a general developing device that develops by contacting or not contacting a developing agent. The developing device 11 is not particularly limited as long as it has the above-mentioned functions, and is selected according to the purpose. For example, a known developer having a function of adhering 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 mentioned. Of these, those using a developing roller in which the developing agent is held on the surface are preferable.

The developer used in the developing apparatus 11 may be a one-component developer containing only toner or a two-component developer containing toner and a carrier. Further, the developer may be magnetic or non-magnetic. Well-known developer is applied.

-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 adopted.

-Transfer device-
Examples of the transfer device 40 include contact-type transfer chargers using belts, rollers, films, rubber blades, etc., scorotron transfer chargers using corona discharge, and transfer chargers known per se, such as corotron transfer chargers. Can be mentioned.

-Intermediate transcript-
As the intermediate transfer body 50, a belt-shaped one (intermediate transfer belt) containing semi-conductive polyimide, polyamide-imide, polycarbonate, polyarylate, polyester, rubber, or the like is used. Further, as the form of the intermediate transfer body, a drum-shaped one may be used in addition to the belt-shaped one.

FIG. 3 is a schematic configuration diagram showing another example of the image forming apparatus according to the present embodiment.
The image forming apparatus 120 shown in FIG. 3 is a tandem type multicolor image forming apparatus equipped with four process cartridges 300. In the image forming apparatus 120, four process cartridges 300 are arranged in parallel on the intermediate transfer body 50, and one electrophotographic photosensitive member is used for each color. The image forming apparatus 120 has the same configuration as the image forming apparatus 100 except that it is a tandem type.

Hereinafter, examples of the present invention will be described, but the present invention is not limited to the following examples. In the examples, "parts" means "parts by mass" and "%" means "% by mass" unless otherwise specified.

<Example 1>
[Formation of undercoat layer]
55 parts by mass of zinc oxide particles (manufactured by Teika Co., Ltd., volume average primary particle size: 85 mm, specific surface area: 12 m ² / g) were mixed with 500 parts by mass of tetrahydrofuran by stirring, and used as a silane coupling agent (surface treatment agent), KBM603. (N-2- (aminoethyl) -3-aminopropyltrimethoxysilane manufactured by Shin-Etsu Chemical Industry Co., Ltd.) was added in an amount of 0.80 part by mass based on 100 parts by mass of zinc oxide particles, and the mixture was stirred for 2 hours. Then, tetrahydrofuran was removed by vacuum distillation and baked at 120 ° C. for 3 hours to obtain zinc oxide particles surface-treated with a silane coupling agent.

100 parts by mass of zinc oxide particles surface-treated with the silane coupling agent, 1 part by mass of anthraquinone as an electron-accepting compound, and 22.5 parts by mass of blocked isocyanate (Sumijour 3173, manufactured by Sumitomo Bavarian Urethane) as a curing agent. And 25 parts by mass of butyral resin (ESREC BM-1, manufactured by Sekisui Chemical Industry Co., Ltd.) were mixed with 142 parts by mass of methyl ethyl ketone to obtain a mixed solution. 38 parts by mass of this mixed solution and 25 parts by mass of methyl ethyl ketone are mixed and dispersed for 5 hours with a sand mill using glass beads having a diameter of 1 mm (that is, dispersion with a dispersion time of 5 hours) to obtain a dispersion. It was.
To the obtained dispersion, 0.008 parts by mass of dioctyltin dilaurate and 6.5 parts by mass of silicone resin particles (Tospearl 145, manufactured by Momentive Performance Materials) were added as catalysts for forming an undercoat layer. The coating liquid of was obtained.
This coating liquid is applied onto an aluminum substrate having a diameter of 30 mm by an immersion coating method, and dried and cured under the conditions of a curing temperature of 183 ° C., a curing time of 24 minutes, and a wind speed of 1.1 m / s to obtain a thickness. A 25 μm undercoat layer was obtained.

[Formation of charge generation layer]
Next, the Bragg angles (2θ ± 0.2 °) of the X-ray diffraction spectrum using CuKα characteristic X-ray as the charge generating material are at least 7.4 °, 16.6 °, 25.5 °, and 28. It consists of 15 parts by mass of chlorogallium phthalocyanine crystal having a diffraction peak at 3 °, 10 parts by mass of vinyl chloride-vinyl acetate copolymer resin (VMCH, manufactured by Nippon Union Carbite), and 300 parts by mass of n-butyl alcohol. The mixture was dispersed in a sand mill for 4 hours using glass beads having a diameter of 1 mm to obtain a coating liquid for forming a charge generation layer. The coating liquid for forming the charge generation layer was immersed and coated on the undercoat layer and dried at 150 ° C. for 5 minutes to obtain a charge generation layer having a thickness of 0.2 μm.

[Formation of charge transport layer]
16 parts by mass of tetrafluorinated ethylene resin particles (average particle size: 3.5 μm) and 3 parts by mass of methacryl copolymer containing an alkyl fluoride group (manufactured by Toa Synthetic Co., Ltd., GF400 (product name)) are combined with toluene (Tol). ) 100 parts by mass, kept at a liquid temperature of 20 ° C., and stirred and mixed for 48 hours to obtain a dispersion liquid A.

Next, as the charge transporting substance, 15 parts by mass of the above-mentioned compound (CT1A) and 30 parts by mass of N, N'-bis (3-methylphenyl) -N, N'-diphenylbenzidine (the above-mentioned compound (CT2A)). And 55 parts by mass of bisphenol Z polycarbonate resin (a homopolymer composed of structural units represented by the following formula (B-1), viscosity average molecular weight: 50,000) as a binder resin, in tetrahydrofuran (THF) 800. It was added to a mass portion and dissolved to obtain a dispersion liquid B.

Next, the dispersion liquid A was added to the dispersion liquid B, and 100 parts by mass of methyl ethyl ketone (MEK) was further added and stirred to obtain a coating liquid 1 for forming a charge transport layer.

Next, the obtained coating liquid 1 for forming a charge transport layer is immersed and coated on the charge generating layer, dried at 140 ° C. for 40 minutes, and the charge transport layer which is a dipping coating film having a film thickness of 30 μm is formed. Formed.

<Examples 2 to 10, Comparative Examples 1 and 2>
Except that the ratio (mass ratio) of toluene (Tol), tetrahydrofuran (THF), and methyl ethyl ketone (MEK), the type and amount of fluororesin particles, and the amount of the fluororesin-containing dispersant were changed according to Table 1, the same as in Example 1. In the same manner, photoconductors of Examples 2 to 10 and Comparative Examples 1 to 2 were obtained, respectively.

<Evaluation of photoconductor>
The photoconductors obtained in each Example and Comparative Example were evaluated as follows.
The abundance Xf of the fluorine-containing dispersant with respect to the fluororesin particles on the surface side of the photosensitive layer, the abundance amount Xr of the fluorine-containing dispersant with respect to the fluororesin particles on the conductive substrate side, and the abundance ratio of Xf to Xr (Xf). / Xr) was measured by XPS by the method described above.

(Evaluation of photoconductor wear)
The electrophotographic photoconductors obtained in each example were mounted on an electrophotographic image forming apparatus (Fuji Xerox Co., Ltd .: DocuCenter f1100) and placed on A3 size paper in an environment of a temperature of 10 ° C. and a humidity of 15% RH. , 100% solid images and 100,000 solid images with 100% image density (area coverage) were formed. The film thickness of the charge transport layer before the image formation and the film thickness of the charge transport layer after the image formation are measured, and the amount of wear is obtained from the difference, and the amount of wear (nm) of the charge transport layer is obtained. ) Was calculated. A permscope manufactured by Fisherscope Co., Ltd. was used as the film thickness measuring instrument.

-Evaluation criteria-
A (◎): Abrasion amount is less than 500 nm B (○): Abrasion amount is 500 nm or more and less than 1000 nm C (Δ): Abrasion amount is 1000 nm or more and less than 1500 nm D (×): Abrasion amount is 1500 nm or more

(Evaluation of ghost)
The electrophotographic photosensitive member obtained in each example was mounted on an electrophotographic image forming apparatus (Fuji Xerox Co., Ltd .: DocuCenter f1100) and placed on A3 size paper in an environment of a temperature of 10 ° C. and a humidity of 15% RH. After outputting one image of the chart of the pattern having the letter G and the black region (black solid portion), one full-face halftone image (Cyan-color full-face halftone image) having an image density of 20% was output.
Then, the output full-face halftone image was observed, and a visual sensory evaluation (grade judgment) was performed. The grade judgment is performed from G to G4 in 1G increments, and the smaller the G number, the better the result. The permissible grade of ghost is G3 or less.

-Evaluation criteria-
G0: Occurrence of ghost is not confirmed.
G1: The occurrence of ghost was slightly confirmed.
G2: Occurrence of ghost was slightly confirmed.
G3: Occurrence of ghost was confirmed.
G4: Many ghosts were confirmed.

From the above results, it can be seen that the electrophotographic photosensitive member of this example has a better evaluation of wear and ghost on the surface of the photoconductor than the electrophotographic photosensitive member of the comparative example. That is, it can be seen that the electrophotographic photosensitive member of this example suppresses the decrease in the life of the photoconductor and suppresses the generation of ghosts as compared with the electrophotographic photosensitive member of the comparative example.

1 Undercoat layer, 2 Charge generation layer, 3 Charge transport layer, 4 Conductive substrate, 7 Electrophotographic photosensitive member, 7A Electrophotographic photosensitive member, 8 Charging device, 9 Exposure device, 11 Develop device, 13 Cleaning device, 14 Lubrication Material, 40 transfer device, 50 intermediate transfer body, 100 image forming device, 120 image forming device, 131 cleaning blade, 132 fibrous member (roll shape), 133 fibrous member (flat brush shape), 300 process cartridge

Claims (9)

With a conductive substrate
A photosensitive layer provided on the conductive substrate and containing fluororesin particles and a dispersant having fluorine atoms, which is measured by X-ray photoelectron spectroscopic analysis and has the fluorine atoms relative to the fluororesin particles on the surface side. When the abundance amount Xf of the dispersant having a fluorine atom and the abundance amount Xr of the dispersant having a fluorine atom with respect to the fluororesin particles on the conductive substrate side, the abundance ratio of the Xf and the Xr is Xf / Xr ≧. A photosensitive layer satisfying the relationship of 1.04 and
An electrophotographic photosensitive member having. The electrophotographic photosensitive member according to claim 1, wherein the content of the dispersant having a fluorine atom in the entire photosensitive layer is 5% by mass or more and 40% by mass or less with respect to the fluororesin particles. The electrophotographic photosensitive member according to claim 2, wherein the content of the dispersant having a fluorine atom in the entire photosensitive layer is 5% by mass or more and 35% by mass or less with respect to the fluororesin particles. The electrophotographic photosensitive member according to any one of claims 1 to 3, wherein the content of the fluororesin particles is 5% by mass or more and 20% by mass or less with respect to the total solid content of the photosensitive layer. The electrophotographic photosensitive member according to claim 4, wherein the content of the fluororesin particles is 6% by mass or more and 10% by mass or less with respect to the total solid content of the photosensitive layer. The electrophotographic photosensitive member according to any one of claims 1 to 5, wherein the Xf is 0.50% or more and 9.80% or less. The electrophotographic photosensitive member according to any one of claims 1 to 6, wherein the Xr is 0.40% or more and 3.60% or less. The electrophotographic photosensitive member according to any one of claims 1 to 7 is provided.
A process cartridge that attaches to and detaches from the image forming device. The electrophotographic photosensitive member according to any one of claims 1 to 7.
A charging means for charging the surface of the electrophotographic photosensitive member and
An electrostatic latent image forming means for forming an electrostatic latent image on the surface of the charged electrophotographic photosensitive member,
A 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, and a developing means.
A transfer means for transferring the toner image to the surface of a recording medium, and
An image forming apparatus comprising.