JP2012203399A - Electrophotographic photoreceptor, image forming apparatus, and process cartridge - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress variation in residual potential due to change in environment.SOLUTION: An electrophotographic photoreceptor includes a conductive substrate 1, and a photosensitive layer 2 on the conductive substrate 1. A layer that constitutes the outermost surface layer of the photosensitive layer 2 (a protection layer 2C) contains a polymer of a charge transport material (A) having a plurality of hydroxyl groups and a charge transport material (B) having no reactive substituent groups. The content ratio of the charge transport material (B) in the entire charge transport materials is 0.19 wt.% or more and 1.5 wt.% or less; and the ionization potential of the charge transport material (A) (IpA) and the ionization potential of the charge transport material (B) (IpB) satisfy the following formula (1). IpB+0.2[eV]≥IpA[eV]≥IpB+0.04[eV] formula (1).

Description

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

In an electrophotographic photoreceptor used in an electrophotographic image forming apparatus, it has been proposed to provide a protective layer (surface layer) on the surface.
As a material system for forming the protective layer, for example, a material in which conductive powder is dispersed in a phenol resin (for example, see Patent Document 1) and a material using a chain polymerizable material (for example, see Patent Document 2) have been proposed. Yes. In addition, an image forming apparatus using a photoreceptor in which a charge transport material is contained in a protective layer has been proposed (see, for example, Patent Documents 3 and 4). In addition, a photoreceptor that polymerizes and crosslinks a charge transporting substance having a chain polymerizable functional group has been proposed (see, for example, Patent Document 5).

Japanese Patent No. 3287678 JP 2005-234546 A JP 2006-85033 A JP 2000-292959 A Japanese Patent No. 4429340

  An object of the present invention is to provide a charge transport material in all charge transport materials when it does not contain a polymer of a charge transport material (A) having a plurality of hydroxyl groups and a charge transport material (B) having no reactive substituent. When the ratio of (B) is not 0.19 mass% or more and 1.5 mass% or less, and / or the ionization potential (IpA) of the charge transport material (A) and the ionization potential (IpB) of the charge transport material (B) Compared to the case where the above equation (1) is not satisfied, the variation in the residual potential due to the environmental change is suppressed.

The above problem is solved by the following means. That is,
The invention according to claim 1
A conductive substrate and a photosensitive layer on the conductive substrate;
The layer constituting the outermost surface of the photosensitive layer contains a charge transport material (A) having a plurality of hydroxyl groups and a charge transport material (B) having no reactive substituent,
The ratio of the charge transport material (B) in the total charge transport material is 0.19% by mass or more and 1.5% by mass or less,
An electrophotographic photoreceptor in which the ionization potential (IpA) of the charge transport material (A) and the ionization potential (IpB) of the charge transport material (B) satisfy the following formula (1).
IpB + 0.2 [eV] ≧ IpA [eV] ≧ IpB + 0.04 [eV] Equation (1)

The invention according to claim 2
A charge transport material having a photosensitive layer on a conductive substrate, wherein the layer constituting the outermost surface of the photosensitive layer does not have a reactive substituent with the polymer of the charge transport material (A) having a plurality of hydroxyl groups (B), the ratio of the charge transport material (B) in the total charge transport material is 0.19 mass% or more and 1.5 mass% or less, and the ionization potential of the charge transport material (A) ( An electrophotographic photoreceptor in which IpA) and the ionization potential (IpB) of the charge transport material (B) satisfy the following formula (1):
A charging device for charging the surface of the electrophotographic photosensitive member;
An electrostatic latent image forming apparatus for forming an electrostatic latent image on the surface of the charged electrophotographic photosensitive member;
A developing device for developing the electrostatic latent image with a developer to form a toner image;
A transfer device for transferring the toner image to a transfer medium;
An image forming apparatus.
IpB + 0.2 [eV] ≧ IpA [eV] ≧ IpB + 0.04 [eV] Equation (1)

The invention according to claim 3
A charge transport material having a photosensitive layer on a conductive substrate, wherein the layer constituting the outermost surface of the photosensitive layer does not have a reactive substituent with the polymer of the charge transport material (A) having a plurality of hydroxyl groups (B), the ratio of the charge transport material (B) in the total charge transport material is 0.19 mass% or more and 1.5 mass% or less, and the ionization potential of the charge transport material (A) ( An electrophotographic photoreceptor in which IpA) and the ionization potential (IpB) of the charge transport material (B) satisfy the following formula (1):
The process cartridge is detachable from the image forming apparatus.
IpB + 0.2 [eV] ≧ IpA [eV] ≧ IpB + 0.04 [eV] Equation (1)

  According to the first aspect of the present invention, when the charge transport material (A) having a plurality of hydroxyl groups and the charge transport material (B) having no reactive substituent are not contained, When the ratio of the charge transport material (B) is not 0.19 mass% or more and 1.5 mass% or less, and / or the ionization potential (IpA) of the charge transport material (A) and the ionization of the charge transport material (B) Compared with the case where the potential (IpB) does not satisfy the formula (1), fluctuations in the residual potential due to environmental changes are suppressed.

  According to the invention of claim 2, when the charge transport material (A) having a plurality of hydroxyl groups and the charge transport material (B) having no reactive substituent are not contained, When the ratio of the charge transport material (B) is not 0.19 mass% or more and 1.5 mass% or less, and / or the ionization potential (IpA) of the charge transport material (A) and the ionization of the charge transport material (B) Compared with the case where the potential (IpB) does not satisfy the above formula (1), the occurrence of image quality defects due to environmental changes is suppressed.

  According to the invention of claim 3, when the charge transport material (A) having a plurality of hydroxyl groups and the charge transport material (B) having no reactive substituent are not contained, When the ratio of the charge transport material (B) is not 0.19 mass% or more and 1.5 mass% or less, and / or the ionization potential (IpA) of the charge transport material (A) and the ionization of the charge transport material (B) Compared with the case where the potential (IpB) does not satisfy the above formula (1), the occurrence of image quality defects due to environmental changes is suppressed.

1 is a schematic partial cross-sectional view showing an electrophotographic photosensitive member of a first aspect used in the present embodiment. It is a general | schematic fragmentary sectional view which shows the electrophotographic photoreceptor of the 2nd aspect used for this embodiment. 1 is a schematic configuration diagram illustrating an image forming apparatus according to an exemplary embodiment. It is a schematic block diagram which shows the other image forming apparatus which concerns on this embodiment.

  Hereinafter, embodiments of the present invention will be described in detail.

<Electrophotographic photoreceptor>
The electrophotographic photoreceptor according to the exemplary embodiment (hereinafter simply referred to as “photoreceptor”) includes a conductive substrate and a photosensitive layer on the conductive substrate, and constitutes the outermost surface of the photosensitive layer. A layer (hereinafter simply referred to as “surface layer”) contains a polymer of a charge transport material (A) having a plurality of hydroxyl groups and a charge transport material (B) having no reactive substituent, and is capable of transporting all charges. The ratio of the charge transport material (B) in the material is 0.19% by mass or more and 1.5% by mass or less, and the ionization potential (IpA) of the charge transport material (A) and the charge transport material (B) The ionization potential (IpB) satisfies the following formula (1).
IpB + 0.2 [eV] ≧ IpA [eV] ≧ IpB + 0.04 [eV] Equation (1)

  Residual hydroxyl groups remaining without reacting exist in the surface layer of the photoreceptor formed by polymerizing a charge transport material having hydroxyl groups. This residual hydroxyl group may interact due to environmental changes such as humidity change and discharge gas exposure in the image forming apparatus, and may form a trap for trapping charges to change the residual potential.

As a result of diligent examination on the fluctuation of the residual potential due to this environmental change, it has no substituent (reactive substituent) for reacting with the charge transport material (A) having a plurality of hydroxyl groups, and the ionization potential (Ip) is It has been found that the fluctuation of the residual potential can be suppressed by adding the charge transport material (B) lower than the range shown in (A) in the above range.
This is because the charge transport material (B) has a lower ionization potential (Ip) than the charge transport material (A) as described above, and is likely to cause an interaction caused by an environmental change (such as humidity change or discharge gas exposure). It is presumed that the interaction is selectively carried out instead of the residual hydroxyl group, and as a result, the fluctuation of the residual potential is suppressed.
In addition, since the content of the charge transport material (B) itself is as small as 1.5% by mass or less as described above, it is considered that the change in the electrical characteristics of the entire surface layer is suppressed. Therefore, it is important that the amount of the charge transport material (B) is in the above range.

-Ionization potential The ionization potential (IpB) of the charge transport material (B) is lower than the ionization potential (IpA) of the charge transport material (A) by 0.04 eV or more and 0.2 eV or less, and further 0.04 eV or more as described above. More preferably, it is 0.18 eV or less.
When the difference in ionization potential between the charge transport material (B) and the charge transport material (A) is less than 0.04 eV, the difference in ionization potential is too small to suppress the variation in residual potential, particularly the residual potential due to humidity. The effect of suppressing fluctuation cannot be obtained. On the other hand, if it is greater than 0.2 eV, the difference in ionization potential is too large, and when an image is formed by repeating charging and discharging, the residual potential varies significantly due to accumulation of the residual potential.

  Here, the ionization potential means the amount of energy required to extract one electron from the ground state of the substance. The ionization potential is measured by irradiating the sample with ultraviolet light that has been dispersed with a monochromator while changing the energy in an air atmosphere, and obtaining the energy at which photoelectrons start to be emitted by the photoelectric effect. The ionization potential of the charge transport material (A) and the charge transport material (B) is measured using an atmospheric photoelectron spectrometer AC-2 manufactured by Riken Keiki Co., Ltd.

-Content ratio The ratio of the said charge transport material (B) in all the charge transport materials contained in a surface layer is 0.19 mass% or more and 1.5 mass% or less, Furthermore, 0.5 mass% or more 1 More preferably, it is 3% by mass or less.
When the content ratio of the charge transport material (B) is less than 0.19% by mass, the content is too small to obtain the effect of suppressing the fluctuation of the residual potential, in particular, the fluctuation of the residual potential due to humidity. On the other hand, if it is larger than 1.5% by mass, the change in the electrical characteristics of the entire surface layer is not suppressed, and when the image is formed by repeating charging and discharging, the residual potential varies significantly due to the accumulation of the residual potential. To do.
Hereinafter, the configuration of the photoreceptor in the present embodiment will be described.

-Structure of photoconductor-
The photosensitive layer according to the present embodiment may have a function-integrated type photosensitive layer having both charge transporting ability and charge generating ability, or a function separation type photosensitive layer including a charge transporting layer and a charge generating layer. You may have. Furthermore, you may provide other layers, such as an undercoat layer and a protective layer.

Hereinafter, the configuration of the photoconductor in the present embodiment will be described with reference to FIGS. 1 and 2, but the present embodiment is not limited to FIGS. 1 and 2.
FIG. 1 is a schematic cross-sectional view showing an example of the layer structure of the photoreceptor in this embodiment. In FIG. 1, 1 is a conductive substrate, 2 is a photosensitive layer, 2A is a charge generation layer, 2B is a charge transport layer, 2C represents a protective layer and 4 represents an undercoat layer.
The photoreceptor shown in FIG. 1 has a layer structure in which an undercoat layer 4, a charge generation layer 2A, a charge transport layer 2B, and a protective layer 2C are laminated on a conductive substrate 1 in this order. It is composed of three layers including a generation layer 2A, a charge transport layer 2B, and a protective layer 2C (the photoreceptor of the first embodiment).
In the photoreceptor shown in FIG. 1, the protective layer 2C is a surface layer constituting the outermost surface.

FIG. 2 is a schematic cross-sectional view showing another example of the layer structure of the photoreceptor in the present embodiment, and the reference numerals shown in FIG. 2 are synonymous with those shown in FIG.
The photoreceptor shown in FIG. 2 has a layer structure in which an undercoat layer 4, a charge generation layer 2A, and a charge transport layer 2B are laminated in this order on a conductive substrate 1, and the photosensitive layer 2 includes the charge generation layer 2A and the charge generation layer 2A. It is composed of two layers of the charge transport layer 2B (photoconductor of the second aspect).
In the photoreceptor shown in FIG. 2, the charge transport layer 2B is a surface layer constituting the outermost surface.

  In the embodiment shown in FIG. 1, the photosensitive layer 2 is composed of three layers including the charge generation layer 2A, the charge transport layer 2B and the protective layer 2C as described above. As an aspect having a charge transport layer 2B, a charge generation layer 2A, and a protective layer 2C in this order from the conductive substrate 1 side, an aspect having a function-integrated type photosensitive layer and a protective layer 2C having both charge transport ability and charge generation ability Etc.

  Hereinafter, each of the first to second aspects will be described as an example of the photoconductor in the present exemplary embodiment.

[Photoreceptor of First Aspect: Surface Layer = Protective Layer]
As shown in FIG. 1, the photoreceptor of the first embodiment has a layer structure in which an undercoat layer 4, a charge generation layer 2A, a charge transport layer 2B, and a protective layer 2C are laminated in this order on a conductive substrate 1. The protective layer 2C is a surface layer.

Conductive substrate As the conductive substrate 1, a conductive substrate having conductivity is used. For example, a metal or alloy such as aluminum, copper, zinc, stainless steel, chromium, nickel, molybdenum, vanadium, indium, gold, platinum, or the like Paper, plastic coated, vapor-deposited, or laminated with metal plates, metal drums, and metal belts, or conductive polymers, conductive compounds such as indium oxide, and metals or alloys such as aluminum, palladium, and gold A film, a belt, etc. are mentioned. Here, “conductive” means that the volume resistivity is less than 10 ¹³ Ωcm.

  If the photoreceptor of the first aspect is used in a laser printer, the surface of the conductive substrate 1 is desirably roughened to a center line average roughness Ra of 0.04 μm or more and 0.5 μm or less. However, when non-interfering light is used as a light source, roughening is not particularly required.

  Surface roughening methods include wet honing by suspending an abrasive in water and spraying it on the support, or centerless grinding and anodization in which the support is brought into contact with a rotating grindstone and continuously ground. Processing is desirable.

  Further, as another roughening method, a conductive or semiconductive powder is dispersed in a resin without roughening the surface of the conductive substrate 1, and a layer is formed on the surface of the support. A method of roughening with particles dispersed in the layer is also desirably used.

  Here, the roughening treatment by anodic oxidation is to form an oxide film on the aluminum surface by anodizing in an electrolyte solution using aluminum as an anode. Examples of the electrolyte solution include a sulfuric acid solution and an oxalic acid solution. However, since the porous anodic oxide film formed by anodic oxidation is chemically active as it is, fine pores of the anodic oxide film may be added to pressurized water vapor or boiling water (metal salt such as nickel may be added). It is desirable to perform a sealing treatment to block the volume expansion due to the hydration reaction, and to change to a more stable hydrated oxide. The thickness of the anodic oxide film is desirably 0.3 μm or more and 15 μm or less.

Further, the conductive substrate 1 may be subjected to treatment with an acidic aqueous solution or boehmite treatment.
The treatment with an acidic treatment solution containing phosphoric acid, chromic acid and hydrofluoric acid is carried out as follows. First, an acidic treatment liquid is prepared. The mixing ratio of phosphoric acid, chromic acid and hydrofluoric acid in the acidic treatment liquid is such that phosphoric acid is in the range of 10% by mass to 11% by mass, chromic acid is in the range of 3% by mass to 5% by mass, and hydrofluoric acid is 0. The concentration of these acids is preferably in the range of 13.5 mass% to 18 mass%. The treatment temperature is desirably 42 ° C. or higher and 48 ° C. or lower. The film thickness is preferably from 0.3 μm to 15 μm.

  The boehmite treatment is performed by immersing in pure water of 90 ° C. or more and 100 ° C. or less for 5 minutes or more and 60 minutes or less, or by contacting with heated steam of 90 ° C. or more and 120 ° C. or less for 5 minutes or more and 60 minutes or less. The film thickness is preferably 0.1 μm or more and 5 μm or less. This is further anodized using an electrolyte solution with lower film solubility than other types such as adipic acid, boric acid, borate, phosphate, phthalate, maleate, benzoate, tartrate, citrate, etc. It may be processed.

-Undercoat layer The undercoat layer 4 is comprised as a layer which contained the inorganic particle in binder resin, for example.
As the inorganic particles, those having a powder resistance (volume resistivity) of 10 ² Ω · cm to 10 ¹¹ Ω · cm are desirably used.

  Among these, inorganic particles (conductive metal oxide) such as tin oxide, titanium oxide, zinc oxide and zirconium oxide are preferably used as the inorganic particles having the above resistance value, and zinc oxide is particularly preferably used.

  In addition, the inorganic particles may be subjected to a surface treatment, or may be used as a mixture of two or more types such as those having different surface treatments or particles having different particle diameters. The volume average particle size of the inorganic particles is desirably in the range of 50 nm to 2000 nm (desirably 60 to 1000).

As the inorganic particles, those having a specific surface area of 10 m ² / g or more by the BET method are desirably used.

  Further, in addition to the inorganic particles, an acceptor compound may be contained. Any acceptor compound may be used. For example, quinone compounds such as chloranil and bromoanil, tetracyanoquinodimethane compounds, 2,4,7-trinitrofluorenone, 2,4,5,7- Fluorenone compounds such as tetranitro-9-fluorenone, 2- (4-biphenyl) -5- (4-tert-butylphenyl) -1,3,4-oxadiazole and 2,5-bis (4-naphthyl)- Oxadiazole compounds such as 1,3,4-oxadiazole, 2,5-bis (4-diethylaminophenyl) 1,3,4-oxadiazole, xanthone compounds, thiophene compounds, 3,3 ′, Electron transporting substances such as diphenoquinone compounds such as 5,5′tetra-t-butyldiphenoquinone are desirable, and in particular, anthraquinone structure Compounds is desired. Furthermore, acceptor compounds having an anthraquinone structure such as hydroxyanthraquinone compounds, aminoanthraquinone compounds, aminohydroxyanthraquinone compounds, and the like are desirably used, and specific examples include anthraquinone, alizarin, quinizarin, anthralfin, and purpurin.

  The content of these acceptor compounds may be arbitrarily set, but is desirably 0.01% by mass or more and 20% by mass or less with respect to the inorganic particles. Furthermore, 0.05 mass% or more and 10 mass% or less are desirable.

  The acceptor compound may be added only when the undercoat layer 4 is applied, or may be previously attached to the surface of the inorganic particles. Examples of the method for imparting the acceptor compound to the surface of the inorganic particles include a dry method or a wet method.

  When surface treatment is performed by a dry method, the inorganic particles are treated by dropping an acceptor compound dissolved in an organic solvent directly or with dry air or nitrogen gas while stirring with a mixer having a large shearing force. The The addition or spraying is preferably performed at a temperature below the boiling point of the solvent. After addition or spraying, baking may be performed at 100 ° C. or higher. About baking temperature and time, it implements in arbitrary ranges.

  As the wet method, the inorganic particles are stirred in a solvent, dispersed using ultrasonic waves, a sand mill, an attritor, a ball mill, or the like, and after adding or accepting an acceptor compound, the solvent is removed. The solvent removal method is distilled off by filtration or distillation. After removing the solvent, baking may be performed at 100 ° C. or higher. About baking temperature and time, it implements in arbitrary ranges. In the wet method, the water containing inorganic particles may be removed before adding the surface treatment agent. For example, a method of removing with stirring and heating in a solvent used for the surface treatment, a method of removing by azeotropic distillation with the solvent. May be used.

  In addition, the inorganic particles may be subjected to a surface treatment before the acceptor compound is provided. The surface treatment agent is selected from known materials. For example, a silane coupling agent, a titanate coupling agent, an aluminum coupling agent, a surfactant, and the like can be given. In particular, a silane coupling agent is desirably used. Furthermore, a silane coupling agent having an amino group is also desirably used.

  Any material may be used as the silane coupling agent having an amino group. Specific examples include γ-aminopropyltriethoxysilane, N-β- (aminoethyl) -γ-aminopropyltrimethoxysilane, N -Β- (aminoethyl) -γ-aminopropylmethylmethoxysilane, N, N-bis (β-hydroxyethyl) -γ-aminopropyltriethoxysilane, and the like. However, it is not limited to these.

  Two or more silane coupling agents may be mixed and used. Examples of silane coupling agents that may be used in combination with the silane coupling agent having an amino group include vinyltrimethoxysilane, γ-methacryloxypropyl-tris (β-methoxyethoxy) silane, β- (3 , 4-epoxycyclohexyl) ethyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, vinyltriacetoxysilane, γ-mercaptopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N-β- (aminoethyl) -Γ-aminopropyltrimethoxysilane, N-β- (aminoethyl) -γ-aminopropylmethyldimethoxysilane, N, N-bis (β-hydroxyethyl) -γ-aminopropyltriethoxysilane, γ-chloropropyl Examples include trimethoxysilane. However, it is not limited to these.

  As the surface treatment method, any known method can be used, but a dry method or a wet method is preferably used. Moreover, you may perform acceptor provision and surface treatment by a coupling agent etc. in parallel.

  Although the quantity of the silane coupling agent with respect to the inorganic particle in the undercoat layer 4 is set arbitrarily, 0.5 mass% or more and 10 mass% or less are desirable with respect to an inorganic particle.

  As the binder resin contained in the undercoat layer 4, any known resin can be used. For example, acetal resin such as polyvinyl butyral, polyvinyl alcohol resin, casein, polyamide resin, cellulose resin, gelatin, polyurethane resin, polyester Resins, methacrylic resins, acrylic resins, polyvinyl chloride resins, polyvinyl acetate resins, vinyl chloride-vinyl acetate-maleic anhydride resins, silicone resins, silicone-alkyd resins, phenol resins, phenol-formaldehyde resins, melamine resins, urethane resins, etc. These known polymer resin compounds, charge transporting resins having a charge transporting group, conductive resins such as polyaniline, and the like are used. Among these, resins that are insoluble in the upper coating solvent are preferably used, and phenol resins, phenol-formaldehyde resins, melamine resins, urethane resins, epoxy resins, and the like are particularly preferable. When these are used in combination of two or more, the mixing ratio is set as necessary.

  In addition, the ratio of the metal oxide and binder resin which provided acceptor property in the coating liquid for undercoat layer formation or an inorganic particle and binder resin is set arbitrarily.

Various additives may be used in the undercoat layer 4. As additives, known materials such as polycyclic condensation type, azo type electron transporting pigments, zirconium chelate compounds, titanium chelate compounds, aluminum chelate compounds, titanium alkoxide compounds, organic titanium compounds, silane coupling agents and the like are used. It is done. The silane coupling agent is used for the surface treatment of the metal oxide, but may be further added to the coating solution as an additive. Specific examples of the silane coupling agent used here include vinyltrimethoxysilane, γ-methacryloxypropyl-tris (β-methoxyethoxy) silane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, γ. -Glycidoxypropyltrimethoxysilane, vinyltriacetoxysilane, γ-mercaptopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N-β- (aminoethyl) -γ-aminopropyltrimethoxysilane, N-β -(Aminoethyl) -γ-aminopropylmethyldimethoxysilane, N, N-bis (β-hydroxyethyl) -γ-aminopropyltriethoxysilane, γ-chloropropyltrimethoxysilane and the like.
Examples of zirconium chelate compounds include zirconium butoxide, zirconium zirconium acetoacetate, zirconium triethanolamine, acetylacetonate zirconium butoxide, ethyl zirconium acetoacetate, zirconium acetate, zirconium oxalate, zirconium lactate, zirconium phosphonate, zirconium octoate, naphthene. Zirconate, zirconium laurate, zirconium stearate, zirconium isostearate, methacrylate zirconium butoxide, stearate zirconium butoxide, isostearate zirconium butoxide and the like.

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

  Examples of the aluminum chelate compound include aluminum isopropylate, monobutoxy aluminum diisopropylate, aluminum butyrate, ethyl acetoacetate aluminum diisopropylate, aluminum tris (ethyl acetoacetate) and the like.

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

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

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

  As a dispersion method, 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 are used. Further, as the coating method used when the undercoat layer 4 is provided, usual methods such as a blade coating method, a wire bar coating method, a spray coating method, a dip coating method, a bead coating method, an air knife coating method, and a curtain coating method are used. Is used.

The undercoat layer 4 is formed on the conductive substrate 1 using the coating solution for forming the undercoat layer thus obtained.
The undercoat layer 4 preferably has a Vickers strength of 35 or more.
Furthermore, the undercoat layer 4 may be set to any thickness, but the thickness is preferably 15 μm or more, and more preferably 15 μm or more and 50 μm or less.

  Further, the surface roughness (ten-point average roughness) of the undercoat layer 4 is from 1 / 4n (n is the refractive index of the upper layer) to 1 / 2λ of the exposure laser wavelength λ used to prevent moire images. Adjusted to In order to adjust the surface roughness, particles such as a resin may be added to the undercoat layer. As the resin particles, silicone resin particles, cross-linked polymethyl methacrylate resin particles and the like are used.

The undercoat layer 4 contains a binder resin and a conductive metal oxide, and has a light transmittance of 40% or less (more preferably 10% or more and 35% or less, more preferably 15%) with respect to light having a wavelength of 950 nm at a thickness of 20 μm. % Or more and 30% or less).
The light transmittance of the undercoat layer is measured as follows. The undercoat layer-forming coating solution is applied on a glass plate so that the thickness after drying is 20 μm, and after drying, the light transmittance of the film at a wavelength of 950 nm is measured using a spectrophotometer. For the light transmittance by the photometer, an apparatus name “Spectrophotometer (U-2000): manufactured by Hitachi, Ltd.” is used as a spectrophotometer.

  The light transmittance of the undercoat layer can be controlled by adjusting the dispersion time during dispersion using the roll mill, ball mill, vibration ball mill, attritor, sand mill, colloid mill, paint shaker, or the like. The dispersion time is not particularly limited, but is preferably 5 minutes to 1000 hours, and more preferably 30 minutes to 10 hours. When the dispersion time is increased, the light transmittance tends to decrease.

  Further, the undercoat layer may be polished for adjusting the surface roughness. As a polishing method, buffing, sandblasting, wet honing, grinding, or the like is used.

  The coated layer is dried to obtain an undercoat layer. Usually, the drying is performed at a temperature at which the solvent can be evaporated to form a film.

Charge generation layer The charge generation layer 2A is preferably a layer containing at least a charge generation material and a binder resin.
Examples of the charge generation material include azo pigments such as bisazo and trisazo, condensed aromatic pigments such as dibromoanthanthrone, perylene pigments, pyrrolopyrrole pigments, phthalocyanine pigments, zinc oxide, and trigonal selenium. Among these, metal and / or metal-free phthalocyanine pigments are desirable for near-infrared laser exposure. In particular, hydroxygallium disclosed in JP-A-5-263007, JP-A-5-279591, and the like. Phthalocyanine, chlorogallium phthalocyanine disclosed in JP-A-5-98181, dichlorotin phthalocyanine disclosed in JP-A-5-140472, JP-A-5-140473, etc., JP-A-4-189873, More preferred is titanyl phthalocyanine disclosed in JP-A-5-43823. For near-ultraviolet laser exposure, condensed aromatic pigments such as dibromoanthanthrone, thioindigo pigments, porphyrazine compounds, zinc oxide, and trigonal selenium are more desirable. As the charge generation material, an inorganic pigment is desirable when a light source with an exposure wavelength of 380 nm to 500 nm is used, and a metal and a metal-free phthalocyanine pigment are desirable when a light source with an exposure wavelength of 700 nm or less and 800 nm is used.

  As the charge generation material, it is desirable to use a hydroxygallium phthalocyanine pigment having a maximum peak wavelength in a range of 810 nm to 839 nm in a spectral absorption spectrum in a wavelength range of 600 nm to 900 nm. This hydroxygallium phthalocyanine pigment is different from the conventional V-type hydroxygallium phthalocyanine pigment, and the maximum peak wavelength of the spectral absorption spectrum is shifted to a shorter wavelength side than the conventional V-type hydroxygallium phthalocyanine pigment. .

The hydroxygallium phthalocyanine pigment having the maximum peak wavelength in the range of 810 nm to 839 nm is preferably in a specific range for the average particle size and in a specific range for the BET specific surface area. Specifically, the average particle size is desirably 0.20 μm or less, more desirably 0.01 μm or more and 0.15 μm or less, while the BET specific surface area is desirably 45 m ² / g or more. 50 m ² / g or more is more desirable, and 55 m ² / g or more and 120 m ² / g or less is particularly desirable. The average particle size is a volume average particle size (d50 average particle size) measured by a laser diffraction / scattering particle size distribution analyzer (LA-700, manufactured by Horiba, Ltd.). Moreover, it is the value measured by the nitrogen substitution method using the BET-type specific surface area measuring device (Shimadzu Corporation make: Flow soap II2300).

  The maximum particle size (maximum primary particle size) of the hydroxygallium phthalocyanine pigment is desirably 1.2 μm or less, more desirably 1.0 μm or less, and further desirably 0.3 μm or less. is there.

Further, the hydroxygallium phthalocyanine pigment preferably has an average particle size of 0.2 μm or less, a maximum particle size of 1.2 μm or less, and a specific surface area value of 45 m ² / g or more.

  In addition, the hydroxygallium phthalocyanine pigment described above has Bragg angles (2θ ± 0.2 °) of 7.5 °, 9.9 °, 12.5 °, and 16.5 in an X-ray diffraction spectrum using CuKα characteristic X-rays. It is desirable to have diffraction peaks at 3 °, 18.6 °, 25.1 ° and 28.3 °.

  The hydroxygallium phthalocyanine pigment preferably has a thermal weight reduction rate of 2.0% or more and 4.0% or less when heated from 25 ° C. to 400 ° C., and preferably 2.5% or more and 3.8%. % Or less is more desirable.

The binder resin used for the charge generation layer 2A is selected from a wide range of insulating resins, and selected from organic photoconductive polymers such as poly-N-vinylcarbazole, polyvinylanthracene, polyvinylpyrene, and polysilane. Also good. Desirable binder resins include polyvinyl butyral resins, polyarylate resins (polycondensates of bisphenols and aromatic divalent carboxylic acids, etc.), polycarbonate resins, polyester resins, phenoxy resins, vinyl chloride-vinyl acetate copolymers, polyamides. Resins, acrylic resins, polyacrylamide resins, polyvinyl pyridine resins, cellulose resins, urethane resins, epoxy resins, caseins, polyvinyl alcohol resins, polyvinyl pyrrolidone resins, and the like. These binder resins are used alone or in combination of two or more. The blending ratio of the charge generation material and the binder resin is preferably in the range of 10: 1 to 1:10 by mass ratio. Here, “insulating” means that the volume resistivity is 10 ¹³ Ωcm or more.

The charge generation layer 2A is formed using, for example, a coating liquid in which the charge generation material and the binder resin are dispersed in a solvent.
Solvents used for dispersion include methanol, ethanol, n-propanol, n-butanol, benzyl alcohol, methyl cellosolve, ethyl cellosolve, acetone, methyl ethyl ketone, cyclohexanone, methyl acetate, n-butyl acetate, dioxane, tetrahydrofuran, and methylene chloride. , Chloroform, chlorobenzene, toluene and the like. These may be used alone or in admixture of two or more.

  Further, as a method for dispersing the charge generating material and the binder resin in the solvent, usual methods such as a ball mill dispersion method, an attritor dispersion method, and a sand mill dispersion method are used. Further, at the time of dispersion, it is effective that the average particle size of the charge generating material is 0.5 μm or less, desirably 0.3 μm or less, and more desirably 0.15 μm or less.

  Further, when forming the charge generation layer 2A, a usual method such as a blade coating method, a Mayer bar coating method, a spray coating method, a dip coating method, a bead coating method, an air knife coating method, or a curtain coating method is used. .

  The film thickness of the charge generation layer 2A thus obtained is desirably 0.1 μm or more and 5.0 μm or less, and more desirably 0.2 μm or more and 2.0 μm or less.

Charge transport layer The charge transport layer 2B is preferably a layer containing at least a charge transport material and a binder resin, or a layer containing a polymer charge transport material.
Charge transport materials include quinone compounds such as p-benzoquinone, chloranil, bromanyl, anthraquinone, tetracyanoquinodimethane compounds, fluorenone compounds such as 2,4,7-trinitrofluorenone, xanthone compounds, benzophenone compounds , Electron transport compounds such as cyanovinyl compounds and ethylene compounds, triarylamine compounds, benzidine compounds, arylalkane compounds, aryl-substituted ethylene compounds, stilbene compounds, anthracene compounds, hydrazone compounds, etc. Examples thereof include pore transporting compounds. These charge transport materials may be used alone or in combination of two or more, but are not limited thereto.

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

(In Structural Formula (a-1), R ⁸ represents a hydrogen atom or a methyl group. N represents 1 or 2. Ar ⁶ and Ar ⁷ are each independently a substituted or unsubstituted aryl group, —C _6. H ₄ —C (R ⁹ ) ═C (R ¹⁰ ) (R ¹¹ ), or —C ₆ H ₄ —CH═CH—CH═C (R ¹² ) (R ¹³ ), wherein R ^{9 to} R ¹³ are Each independently represents a hydrogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aryl group, including a halogen atom, an alkyl group having 1 to 5 carbon atoms, and an alkoxy group having 1 to 5 carbon atoms; A substituted amino group substituted with a group or an alkyl group having 1 to 3 carbon atoms.)

(In Structural Formula (a-2), R ¹⁴ and R ^{14 ′} may be the same or different and each independently represents a hydrogen atom, a halogen atom, an alkyl group having 1 to 5 carbon atoms, or 1 to 5 carbon atoms. R ¹⁵ , R ^{15 ′} , R ¹⁶ and R ^{16 ′} may be the same or different and each independently represents a hydrogen atom, a halogen atom, an alkyl group having 1 to 5 carbon atoms, or 1 carbon atom. Or more, an alkoxy group having 5 or less, an amino group substituted with an alkyl group having 1 to 2 carbon atoms, a substituted or unsubstituted aryl group, -C (R ¹⁷ ) = C (R ¹⁸ ) (R ¹⁹ ), or- CH = CH—CH═C (R ²⁰ ) (R ²¹ ), wherein R ^{17 to} R ²¹ each independently represents a hydrogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aryl group. And n are independent of each other 0 or 2 show the following integer.)

Here, among the triarylamine derivatives represented by the structural formula (a-1) and the benzidine derivatives represented by the structural formula (a-2), in particular, “—C ₆ H ₄ —CH═CH—CH Triarylamine derivatives having “═C (R ¹² ) (R ¹³ )” and benzidine derivatives having “—CH═CH—CH═C (R ²⁰ ) (R ²¹ )” are desirable.

  The binder resin used for the charge transport layer 2B 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-vinyl carbazole, polysilane, etc. are mentioned. Further, as described above, a polymer charge transport material such as a polyester-based polymer charge transport material disclosed in JP-A-8-176293 and JP-A-8-208820 may be used. These binder resins are used alone or in combination of two or more. The blending ratio of the charge transport material and the binder resin is desirably 10: 1 to 1: 5 by mass ratio.

  The binder resin is not particularly limited, but at least one of a polycarbonate resin having a viscosity average molecular weight of 50,000 to 80,000 and a polyarylate resin having a viscosity average molecular weight of 50,000 to 80,000 is desirable.

  In addition, a polymer charge transport material may be used as the charge transport material. As the polymer charge transporting material, known materials having charge transporting properties such as poly-N-vinylcarbazole and polysilane are used. In particular, polyester polymer charge transport materials disclosed in JP-A-8-176293 and JP-A-8-208820 are particularly desirable. Although the polymer charge transport material can be formed by itself, it may be formed by mixing with a binder resin described later.

  The charge transport layer 2B is formed using, for example, a charge transport layer forming coating solution containing the above-described constituent materials. Solvents used in the coating solution for forming the charge transport layer include aromatic hydrocarbons such as benzene, toluene, xylene and chlorobenzene, ketones such as acetone and 2-butanone, and halogenation such as methylene chloride, chloroform and ethylene chloride. Ordinary organic solvents such as aliphatic hydrocarbons, cyclic ethers such as tetrahydrofuran and ethyl ether, or straight chain ethers may be used alone or in admixture of two or more. Moreover, a well-known method is used as a dispersion method of each said constituent material.

  Coating methods for coating the charge transport layer forming coating solution on the charge generation layer 2A include blade coating method, Mayer bar coating method, spray coating method, dip coating method, bead coating method, air knife coating method, A usual method such as a curtain coating method is used.

  The film thickness of the charge transport layer 2B is desirably 5 μm or more and 50 μm or less, and more desirably 10 μm or more and 30 μm or less.

-Protective layer The surface layer (protective layer 2C in the first embodiment) contains a polymer of a charge transport material (A) having a plurality of hydroxyl groups and a charge transport material (B) having no reactive substituent. To do.

(Charge transport material having a plurality of hydroxyl groups (A))
The charge transport material (A) having a plurality of hydroxyl groups is not particularly limited as long as it is a charge transport material having a plurality of hydroxyl groups that are reactive functional groups. Among them, a charge transport material having a structure represented by the following general formula (I) is preferably used.
_{^{F - ((- R 1 -X}} ) n1 (R 2) n3 -OH) n2 (I)
(In general formula (I), F represents an organic group derived from a compound having a hole transporting ability, and R ¹ and R ² each independently represents a linear or branched chain having 1 to 5 carbon atoms. N1 is 0 or 1, n2 is an integer of 2 or more, 4 or less, n3 is 0 or 1, and X is any one selected from an oxygen atom, a sulfur atom, and a —NH— group .)

  In general formula (I), as the compound having a hole transport ability in an organic group derived from a compound having a hole transport ability represented by F, an arylamine derivative is preferably exemplified. Preferred examples of the arylamine derivative include a triphenylamine derivative and a tetraphenylbenzidine derivative.

  The compound represented by the general formula (I) is preferably a compound represented by the following general formula (II).

(In general formula (II), Ar ^{1 to} Ar ⁴ may be the same or different and each independently represents a substituted or unsubstituted aryl group, and Ar ⁵ represents a substituted or unsubstituted aryl group or a substituted or unsubstituted aryl group. A substituted arylene group, D represents — (— R ¹ —X) _n1 (R ² ) _n3 —OH, c independently represents 0 or 1, k represents 0 or 1, and the total number of D Is from 2 to 4. R ¹ and R ² each independently represents a linear or branched alkylene group having 1 to 5 carbon atoms, n1 represents 0 or 1, and n3 represents 0 Or 1 and X represents an oxygen, NH, or sulfur atom.)

In the general formula (II), “— (— R ¹ —X) _n1 (R ² ) _n3 —OH” representing D has the same meaning as in the general formula (I), and R ¹ and R ² are each independently carbon. A linear or branched alkylene group having a number of 1 or more and 5 or less. N1 is preferably 1. X is preferably oxygen.

  The total number of D in the general formula (II) corresponds to n2 in the general formula (I), and is preferably 3 or more and 4 or less. That is, in general formula (I) or general formula (II), it has 2 or more and 4 or less, more preferably 3 or more and 4 or less “—OH” groups in one molecule.

In general formula (II), Ar ^{1 to} Ar ⁴ are preferably any of the following formulas (1) to (7). The following formulas (1) to (7) are shown together with “-(D) _c ” that can be linked to each of Ar ^{1 to} Ar ⁴ .

[In the formulas (1) to (7), R ⁹ is substituted with a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkyl group having 1 to 4 carbon atoms, or an alkoxy group having 1 to 4 carbon atoms. Represents one selected from the group consisting of a phenyl group, an unsubstituted phenyl group, and an aralkyl group having 7 to 10 carbon atoms, wherein R ^{10 to} R ¹² are a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, carbon 1 selected from the group consisting of an alkoxy group having 1 to 4 carbon atoms, a phenyl group substituted with an alkoxy group having 1 to 4 carbon atoms, an unsubstituted phenyl group, an aralkyl group having 7 to 10 carbon atoms, and a halogen atom. Represents a seed, Ar represents a substituted or unsubstituted arylene group, D and c have the same meanings as “D” and “c” in formula (II), s represents 0 or 1, and t represents 1 3 or more It represents an integer. ]

  Here, as Ar in Formula (7), what is represented by following formula (8) or (9) is desirable.

[In formulas (8) and (9), R ¹³ and R ¹⁴ are each a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or an alkoxy group having 1 to 4 carbon atoms. 1 represents one selected from the group consisting of a phenyl group substituted with, an unsubstituted phenyl group, an aralkyl group having 7 to 10 carbon atoms and a halogen atom, and t represents an integer of 1 to 3. ]

  Further, Z ′ in the formula (7) is preferably represented by any one of the following formulas (10) to (17).

[In the formulas (10) to (17), R ¹⁵ and R ¹⁶ are each a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or an alkoxy group having 1 to 4 carbon atoms. 1 represents one selected from the group consisting of a phenyl group substituted with, an unsubstituted phenyl group, an aralkyl group having 7 to 10 carbon atoms, and a halogen atom, W represents a divalent group, q and r each represent Represents an integer of 1 to 10, and t represents an integer of 1 to 3. ]

  W in the formulas (16) to (17) is preferably any one of divalent groups represented by the following (18) to (26). However, in formula (25), u represents an integer of 0 or more and 3 or less.

In general formula (II), Ar ⁵ is the aryl group of the above (1) to (7) exemplified in the description of Ar ^{1 to} Ar ⁴ when k is 0, and when k is 1, An arylene group obtained by removing one hydrogen atom from the above aryl groups (1) to (7) is desirable.

In the general formula (I), examples of the organic group derived from the compound having a hole transporting ability represented by F include triphenylamine skeleton, N, N, N ′, N′-tetraphenylbenzidine skeleton. Is preferred.
These organic groups may have a substituent, and as the substituent, a methyl group, a diphenylvinyl group, a phenyl group, and a halogen atom are preferable, and among them, a methyl group or a diphenylvinyl group is preferable.

Of the groups represented by “(—R ¹ —X) _n1 (R ² ) _n3 ”, n1 is preferably 0 and n3 is preferably 1.
R ² is particularly preferably a methylene group.

  Here, specific examples of the charge transport material (A) having a plurality of hydroxyl groups include the following.

(Charge transport material having no reactive substituent (B))
The charge transport material (B) having no reactive substituent is not particularly limited as long as it is a charge transport material having no reactive substituent. Among these, at least one kind of charge transport material selected from the compounds represented by the following general formula (A) or the following general formula (B) is preferably used.

(In General Formula (A), L ¹ and L ² each independently represent a substituted or unsubstituted alkyl group having 1 to 5 carbon atoms, a substituted or unsubstituted aralkyl group having 7 to 15 carbon atoms, L ³ and L ⁴ each independently represent a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 5 carbon atoms, a substituted or unsubstituted aralkyl group having 7 to 20 carbon atoms, and f and g are each Independently, 1 or 2 is represented.
In general formula (B), L ^{5 to} L ⁸ are each independently a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 5 carbon atoms, a substituted or unsubstituted aralkyl group having 7 to 15 carbon atoms, A substituted or unsubstituted aryl group having 6 to 15 carbon atoms or a structure represented by the following general formula (C); and at least one of L ^{5 to} L ⁸ is represented by the following general formula (C): Has a structure. h to k each independently represent 1 or 2. L ⁹ and L ¹⁰ are each independently a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 5 carbon atoms, a substituted or unsubstituted aralkyl group having 7 to 15 carbon atoms, and a carbon number of 6 to 15 carbon atoms. A substituted or unsubstituted aryl group, or a substituted or unsubstituted amino group having 1 to 15 carbon atoms is shown. )

(In General Formula (C), L ¹ and L ² each independently represents a substituted or unsubstituted alkyl group having 1 to 5 carbon atoms, or a substituted or unsubstituted aralkyl group having 7 to 15 carbon atoms. )

In the general formula (A), the substituted or unsubstituted alkyl group having 1 to 5 carbon atoms representing L ¹ and L ² is preferably an alkyl group having 1 to 3 carbon atoms.

Among the above, as L ¹ and L ² , an ethyl group is preferable.

In the general formula (A), when L ³ and L ⁴ are a substituted or unsubstituted alkyl group having 1 to 5 carbon atoms, the alkyl group is an alkyl group having 1 to 5 carbon atoms. An alkyl group having 1 to 3 carbon atoms is particularly preferable.

Specific examples of preferable alkyl groups represented by L ³ and L ⁴ include a methyl group, an ethyl group, a propyl group, an n-butyl group, an i-butyl group, and a t-butyl group.
Among these, as the substituent of the alkyl group represented by L ³ or L ⁴ , a methyl or ethyl group is most preferable.

When L ³ and L ⁴ are a substituted or unsubstituted aralkyl group having 7 to 20 carbon atoms, the aralkyl group is preferably an aralkyl group having 7 to 15 carbon atoms, and has 7 to 10 carbon atoms. The aralkyl group is particularly preferable.

Among the above, as a substituent which the aralkyl group represented by L ³ and L ⁴ has, a benzyl group is most preferable.

In the general formula (B), when L ^{5 to} L ⁸ are a substituted or unsubstituted alkyl group having 1 to 5 carbon atoms, the alkyl group is an alkyl group having 1 to 5 carbon atoms. An alkyl group having 1 to 3 carbon atoms is particularly preferable.

Specific examples of preferred alkyl groups represented by L ^{5 to} L ⁸ include a methyl group, an ethyl group, a propyl group, an n-butyl group, an i-butyl group, and a t-butyl group.

When L ^{5 to} L ⁸ is a substituted or unsubstituted aralkyl group having 7 to 15 carbon atoms, examples of the aralkyl group include a benzyl group and a phenethyl group. Among these, a benzyl group is particularly preferable.

When L ^{5 to} L ⁸ are substituted or unsubstituted aryl groups having 6 to 15 carbon atoms, examples of these aryl groups include phenyl and biphenylyl groups. Among these, a phenyl group is particularly preferable.

L at ⁵ to in the structure represented by the general formula (C) shown at least one of the ^{L 8,} L 1, ^{L 2} are in the above general formula (A), has the same meaning as ^{L 1} and ^{L 2,} The preferable range is also the same.

In the general formula (A), when one or both of L ⁹ and L ¹⁰ is a substituted or unsubstituted alkyl group having 1 to 5 carbon atoms, the alkyl group has 1 or more carbon atoms. An alkyl group having 5 or less is preferable, and an alkyl group having 1 to 3 carbon atoms is particularly preferable.

Among these, as the substituent that the alkyl group represented by L ⁹ or L ¹⁰ has, a methyl or ethyl group is most preferable.

When either or both of L ⁹ and L ¹⁰ is a substituted or unsubstituted aralkyl group having 7 to 15 carbon atoms, examples of the aralkyl group include benzyl and phenethyl groups. .

When one or both of L ⁹ and L ¹⁰ is a substituted or unsubstituted aryl group having 6 to 15 carbon atoms, examples of these aryl groups include phenyl, biphenylyl group, dimethylaminophenyl, and the like. Preferred examples include a group and a diethylaminophenyl group.

  Specific examples of the compound represented by the general formula (A) or (B) are shown below, but are not limited thereto. The following specific examples (A-1) to (A-6) are specific examples of the compound represented by the general formula (A), and the following specific examples (B-1) to (B-13) are Specific examples of the compound represented by the general formula (B) are shown below.

  The charge transport material (B) having no reactive substituent such as the compounds represented by the general formula (A) and the general formula (B) may be used alone or in combination of two or more. May be.

  The ratio of the charge transport material (B) in the total charge transport material contained in the surface layer (the protective layer 2C in the first embodiment) is 0.19% by mass or more and 1.5% by mass or less.

(Difference in ionization potential between charge transport material (A) and charge transport material (B))
The ionization potential (IpB) of the charge transport material (B) used for the surface layer is 0.04 eV or more and 0.2 eV or less lower than the ionization potential (IpA) of the charge transport material (A).
The difference in ionization potential is controlled by the selection of materials used as the charge transport material (A) and the charge transport material (B), and is performed by using a combination in which the difference in ionization potential falls within the above range.

(Other charge transport materials)
In addition to the charge transport material (A) having a plurality of hydroxyl groups and the charge transport material (B) having no reactive substituent, the protective layer 2C has other charge transport properties having a reactive functional group. Substances may be used in combination. For example, at least one charge transport material having a structure represented by the following general formula (III) may be used in combination.
^{_{F - ((- R 1 -X}} ) n1 (R 2) n3 -Y) n2 (III)
(In general formula (III), F represents an organic group derived from a compound having a hole transporting ability, and R ¹ and R ² each independently represents a linear or branched chain having 1 to 5 carbon atoms. N1 is 0 or 1, n2 is an integer of 1 to 4, n3 is 0 or 1, X is any one selected from an oxygen atom, a sulfur atom and a —NH— group, Represents —OR ³ , —NH ₂ , —SH or —COOH group, and R ³ represents an alkyl group.)

  In addition, it is preferable that the total charge transporting substance is polymerized at a ratio of 90% by mass or more with respect to the total amount of monomers as the solid content of the surface layer (protective layer 2C in the first embodiment).

(Guanamine compounds and melamine compounds)
The protective layer 2C formed by polymerizing the charge transport material (A) and the charge transport material (B) may be formed by further polymerizing with at least one selected from a guanamine compound and a melamine compound.

First, the guanamine compound will be described.
The guanamine compound is a compound having a guanamine skeleton (structure), and examples thereof include acetoguanamine, benzoguanamine, formoguanamine, steroguanamine, spiroguanamine, and cyclohexylguanamine.

  The guanamine compound is particularly preferably at least one of a compound represented by the following general formula (A) and a multimer thereof. Here, the multimer is an oligomer polymerized using the compound represented by the general formula (A) as a structural unit, and the degree of polymerization thereof is, for example, 2 or more and 200 or less (preferably 2 or more and 100 or less). In addition, the compound shown by general formula (A) may be used individually by 1 type, but may use 2 or more types together.

In General Formula (A), R ¹ is a linear or branched alkyl group having 1 to 10 carbon atoms, a substituted or unsubstituted phenyl group having 6 to 10 carbon atoms, or 4 to 10 carbon atoms. The following substituted or unsubstituted alicyclic hydrocarbon groups are shown. R ^{2 to} R ⁵ each independently represent hydrogen, —CH ₂ —OH, or —CH ₂ —O—R ⁶ . R ⁶ represents hydrogen or a linear or branched alkyl group having 1 to 10 carbon atoms.

In general formula (A), the alkyl group represented by R ¹ has 1 to 10 carbon atoms, preferably 1 to 8 carbon atoms, more preferably 1 to 5 carbon atoms. . The alkyl group may be linear or branched.

In general formula (A), the phenyl group represented by R ¹ has 6 to 10 carbon atoms, and more preferably 6 to 8 carbon atoms. Examples of the substituent substituted with the phenyl group include a methyl group, an ethyl group, and a propyl group.

In general formula (A), the alicyclic hydrocarbon group representing R ¹ has 4 to 10 carbon atoms, and more preferably 5 to 8 carbon atoms. Examples of the substituent substituted with the alicyclic hydrocarbon group include a methyl group, an ethyl group, and a propyl group.

In the general formula (A), in “—CH ₂ —O—R ⁶ ” representing R ^{2 to} R ⁵ , the alkyl group representing R ⁶ has 1 to 10 carbon atoms, and desirably has carbon atoms. 1 to 8 and more preferably 1 to 6 carbon atoms. The alkyl group may be linear or branched. Desirably, a methyl group, an ethyl group, a butyl group, etc. are mentioned.

As the compound represented by the general formula (A), it is particularly desirable that R ¹ represents a substituted or unsubstituted phenyl group having 6 to 10 carbon atoms, and R ^{2 to} R ⁵ are each independently —CH ₂ —O. It is a compound represented by —R ⁶ . R ⁶ is preferably selected from a methyl group and an n-butyl group.

  The compound represented by the general formula (A) is synthesized by a known method using, for example, guanamine and formaldehyde (for example, see Experimental Chemistry Course 4th edition, Vol. 28, page 430).

  Specific examples of the compound represented by the general formula (A) are shown below, but are not limited thereto. Moreover, although the following specific examples show the thing of a monomer, the multimer (oligomer) which uses these as a structural unit may be sufficient.

  Commercially available products of the compound represented by the general formula (A) include, for example, “Superbecamine (R) L-148-55, Superbecamine (R) 13-535, Superbecamine (R) L-145- 60, Super Becamine (R) TD-126 "or more manufactured by DIC Corporation," Nicarac BL-60, Nicalac BX-4000 "or more manufactured by Nippon Carbide Corporation, and the like.

  In addition, the compound represented by the general formula (A) (including multimers) can be used in a suitable solvent such as toluene, xylene, ethyl acetate, etc., in order to remove the influence of residual catalyst after synthesis or after purchasing a commercial product. It may be dissolved and washed with distilled water, ion exchange water or the like, or may be removed by treatment with an ion exchange resin.

Next, the melamine compound will be described.
The melamine compound is a melamine skeleton (structure), and is preferably at least one of a compound represented by the following general formula (B) and a multimer thereof. Here, the multimer is an oligomer obtained by polymerizing the compound represented by the general formula (B) as a structural unit as in the general formula (A), and the degree of polymerization thereof is, for example, 2 or more and 200 or less (preferably 2 or more and 100). The following). In addition, the compound shown by General formula (B) or its multimer may be used individually by 1 type, but may use 2 or more types together. Moreover, you may use together with the compound shown by the said general formula (A), or its multimer.

In general formula (B), R ^{7 to} R ¹² each independently represent a hydrogen atom, —CH ₂ —OH, —CH ₂ —O—R ¹³ , and R ¹³ is branched from 1 to 5 carbon atoms. Or a good alkyl group. Examples of R ¹³ include a methyl group, an ethyl group, and a butyl group.

  The compound represented by the general formula (B) is synthesized by a known method using, for example, melamine and formaldehyde (for example, synthesized like the melamine resin described in Experimental Chemistry Course 4th edition, Volume 28, page 430). Synthesized.

  Specific examples of the compound represented by the general formula (B) are shown below, but are not limited thereto. Moreover, although the following specific examples show the thing of a monomer, the multimer (oligomer) which uses these as a structural unit may be sufficient.

  As a commercial item of the compound represented by the general formula (B), for example, Super Melami No. 90 (manufactured by NOF Corporation), Super Becamine (R) TD-139-60 (manufactured by DIC), Uban 2020 (Mitsui Chemicals), Sumitex Resin M-3 (Sumitomo Chemical Industries), Nicarak MW-30 (Japan) Carbide).

  In addition, the compound represented by the general formula (B) (including multimers) is dissolved in an appropriate solvent such as toluene, xylene or ethyl acetate after synthesis or after purchase of a commercial product in order to remove the influence of residual catalyst. It may be washed with distilled water, ion exchange water or the like, or may be removed by treatment with ion exchange resin.

  Here, the solid content concentration in the coating liquid for forming the surface layer (protective layer 2C in the first embodiment) selected from guanamine compounds and melamine compounds is 0.1% by mass or more and 5% by mass or less. It is preferable that it is 1 mass% or more and 3 mass% or less.

(Other compositions)
For the protective layer 2C, other thermosetting resins such as a phenol resin, a melamine resin, a urea resin, an alkyd resin, and a benzoguanamine resin may be mixed and used together with a crosslinked product obtained by crosslinking a specific charge transport material. In addition, a compound having a larger number of functional groups in one molecule such as a spiroacetal guanamine resin (for example, “CTU-guanamine” (Ajinomoto Fine Techno Co., Ltd.)) may be copolymerized with the material in the crosslinked product.

  The protective layer 2C may contain fluorine-based resin particles. The fluororesin particles are not particularly limited, but include tetrafluoroethylene resin (PTFE), trifluoroethylene chloride resin, hexafluoropropylene resin, vinyl fluoride resin, vinylidene fluoride resin, 2 It is desirable to select one or two or more kinds of fluorinated ethylene chloride resins and copolymers thereof, more preferably tetrafluoroethylene resin and vinylidene fluoride resin, particularly preferably 4 fluorocarbon resins. It is a hydrogenated ethylene resin.

  The content of the fluororesin particles with respect to the total solid content of the protective layer 2C as the surface layer is preferably 1% by mass or more and 30% by mass or less, and more preferably 2% by mass or more and 20% by mass or less.

  In addition, it is preferable to add a surfactant to the protective layer 2C, and the surfactant to be used is particularly a surfactant that includes at least one type of structure among a fluorine atom, an alkylene oxide structure, and a silicone structure. Although there is no restriction | limiting, What has multiple said structures is mentioned suitably.

  Various things are mentioned as surfactant which has a fluorine atom. Specific examples of the surfactant having a fluorine atom and an acrylic structure include Polyflow KL600 (manufactured by Kyoeisha Chemical Co., Ltd.), F-top EF-351, EF-352, EF-801, EF-802, EF-601 (above, JEMCO Manufactured). The surfactant having an acrylic structure mainly includes those obtained by polymerizing or copolymerizing monomers such as acrylic or methacrylic compounds.

  Further, as the surfactant having a perfluoroalkyl group as a fluorine atom, specifically, perfluoroalkyl sulfonic acids (for example, perfluorobutane sulfonic acid, perfluorooctane sulfonic acid, etc.), perfluoroalkyl carboxylic acids (for example, , Perfluorobutanecarboxylic acid, perfluorooctanecarboxylic acid, etc.) and perfluoroalkyl group-containing phosphates. Perfluoroalkylsulfonic acids and perfluoroalkylcarboxylic acids may be salts thereof and amide-modified products thereof.

Examples of commercially available perfluoroalkyl sulfonic acids include Megafax F-114 (manufactured by DIC Corporation), F-top EF-101, EF102, EF-103, EF-104, EF-105, EF-112, and EF-. 121, EF-122A, EF-122B, EF-122C, EF-123A (manufactured by JEMCO), AK, 501 (manufactured by Neos) and the like.
Examples of commercially available products of perfluoroalkylcarboxylic acids include Megafac F-410 (manufactured by DIC Corporation), F-top EF-201, EF-204 (manufactured by JEMCO Corporation), and the like.
Commercially available perfluoroalkyl group-containing phosphate esters include MegaFac F-493 and F-494 (manufactured by DIC Corporation) F-top EF-123A, EF-123B, EF-125M, EF-132, ( As mentioned above, JEMCO Co., Ltd.) can be cited.

  Examples of the surfactant having an alkylene oxide structure include polyethylene glycol, polyether antifoaming agent, and polyether-modified silicone oil. Polyethylene glycol preferably has a number average molecular weight of 2000 or less. Polyethylene glycol having a number average molecular weight of 2000 or less includes polyethylene glycol 2000 (number average molecular weight 2000), polyethylene glycol 600 (number average molecular weight 600), polyethylene glycol 400 (number average molecular weight 400), polyethylene glycol 200 (number average molecular weight 200). ) And the like.

  Moreover, as a polyether antifoamer, PE-M, PE-L (above, Wako Pure Chemical Industries Ltd. make), antifoam No. 1. Antifoaming agent No. 1 5 (above, manufactured by Kao Corporation).

  Examples of the surfactant having a silicone structure include general silicone oils such as dimethyl silicone, methylphenyl silicone, diphenyl silicone and derivatives thereof.

  Further, as the surfactant having both a fluorine atom and an alkylene oxide structure, those having an alkylene oxide structure or a polyalkylene structure in the side chain, or substituted at the terminal of the alkylene oxide or polyalkylene oxide structure with a substituent containing fluorine And the like. Specific examples of the surfactant having an alkylene oxide structure include, for example, MegaFuck F-443, F-444, F-445, F-446 (above, manufactured by DIC Corporation), POLY FOX PF636, PF6320, and PF6520. , PF656 (made by Kitamura Chemical Co., Ltd.) and the like.

  As surfactants having both an alkylene oxide structure and a silicone structure, KF351 (A), KF352 (A), KF353 (A), KF354 (A), KF355 (A), KF615 (A), KF618, KF945 (A), KF6004 (above, manufactured by Shin-Etsu Chemical Co., Ltd.), TSF4440, TSF4445, TSF4450, TSF4446, TSF4452, TSF4453, TSF4460 (above, manufactured by GE Toshiba Silicon), BYK-300, 302, 306, 307, 310, 315, 320, 322, 323, 325, 330, 331, 333, 337, 341, 344, 345, 346, 347, 348, 370, 375, 377, 378, UV3500, UV3510, UV3570, etc. Made emissions Co., Ltd.) and the like.

  The content of the surfactant is desirably 0.01% by mass or more and 1% by mass or less, more desirably 0.02% by mass or more and 0.5% by mass or less with respect to the total solid content of the protective layer.

  Further, the protective layer 2C may be further mixed with another coupling agent or a fluorine compound. As this compound, various silane coupling agents and commercially available silicone hard coat agents are used.

  As the silane coupling agent, vinyltrichlorosilane, vinyltrimethoxysilane, vinyltriethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, γ-aminopropylmethyldimethoxysilane, N-β (aminoethyl) γ-aminopropyltriethoxysilane, tetramethoxysilane, methyltrimethoxysilane, dimethyldimethoxysilane, and the like are used. As a commercially available hard coat agent, KP-85, X-40-9740, X-8239 (manufactured by Shin-Etsu Silicone), AY42-440, AY42-441, AY49-208 (manufactured by Toray Dow Corning) Etc. are used. In order to impart water repellency and the like, (tridecafluoro-1,1,2,2-tetrahydrooctyl) triethoxysilane, (3,3,3-trifluoropropyl) trimethoxysilane, 3- (hepta) Fluoroisopropoxy) propyltriethoxysilane, 1H, 1H, 2H, 2H-perfluoroalkyltriethoxysilane, 1H, 1H, 2H, 2H-perfluorodecyltriethoxysilane, 1H, 1H, 2H, 2H-perfluorooctyl Fluorine-containing compounds such as triethoxysilane may be added. Although the silane coupling agent is used in an arbitrary amount, the amount of the fluorine-containing compound is desirably 0.25 times or less by mass with respect to the compound not containing fluorine.

Further, a resin that dissolves in alcohol may be added to the protective layer. Here, the alcohol-soluble resin means a resin that can be dissolved by 1% by mass or more in an alcohol having 5 or less carbon atoms. Examples of resins that are soluble in alcohol solvents include polyvinyl acetal resins such as polyvinyl butyral resin, polyvinyl formal resin, and partially acetalized polyvinyl acetal resin in which a part of butyral is modified with formal or acetoacetal (for example, manufactured by Sekisui Chemical Co., Ltd.) ESREC B, K, etc.), polyamide resin, cellulose resin, polyvinylphenol resin and the like. In particular, polyvinyl acetal resin and polyvinyl phenol resin are desirable.
The resin preferably has a weight average molecular weight of 2,000 to 100,000, and more preferably 5,000 to 50,000. The amount of the resin added is preferably 1% by mass or more and 40% by mass or less, more preferably 1% by mass or more and 30% by mass or less, and further preferably 5% by mass or more and 20% by mass or less.

  An antioxidant may be added to the protective layer 2C. Antioxidants are preferably hindered phenols or hindered amines, organic sulfur antioxidants, phosphite antioxidants, dithiocarbamate antioxidants, thiourea antioxidants, benzimidazole antioxidants. , Etc., may be used. The addition amount of the antioxidant is preferably 20% by mass or less, and more preferably 10% by mass or less.

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

  Furthermore, various particles may be added to the protective layer. An example of the particles is silicon-containing particles. Silicon-containing particles are particles containing silicon as a constituent element, and specific examples include colloidal silica and silicone particles. The colloidal silica used as the silicon-containing particles is obtained by dispersing silica having an average particle diameter of 1 nm or more and 100 nm or less, preferably 10 nm or more and 30 nm or less in an organic solvent such as an acidic or alkaline aqueous dispersion, alcohol, ketone, or ester. A commercially available product may be used. The solid content of the colloidal silica in the protective layer 2C is not particularly limited, but is 0.1% by mass or more and 50% by mass or less, preferably 0.1% by mass based on the total solid content of the protective layer. It is used in the range of mass% to 30 mass%.

  The silicone particles used as the silicon-containing particles may be selected from silicone resin particles, silicone rubber particles, and silicone surface-treated silica particles, and commercially available particles may be used. These silicone particles are spherical, and the average particle size is desirably 1 nm or more and 500 nm or less, and more desirably 10 nm or more and 100 nm or less. Silicone particles are particles that are chemically inert and have excellent dispersibility in resins. The content of the silicone particles in the protective layer is preferably 0.1% by mass or more and 30% by mass or less, more preferably 0.5% by mass or more and 10% by mass or less, based on the total solid content of the protective layer. .

Other particles include fluorine-based particles such as ethylene tetrafluoride, ethylene trifluoride, propylene hexafluoride, vinyl fluoride, and vinylidene fluoride, and “8th Polymer Material Forum Lecture Proceedings p89”. As shown, particles made of a resin obtained by copolymerizing a fluororesin and a monomer having a hydroxyl group, ZnO—Al ₂ O ₃ , SnO ₂ —Sb ₂ O ₃ , In ₂ O ₃ —SnO ₂ , ZnO ₂ —TiO ₂ , ZnO Examples thereof include semiconductive metal oxides such as —TiO ₂ , MgO—Al ₂ O ₃ , FeO—TiO ₂ , TiO ₂ , SnO ₂ , In ₂ O ₃ , ZnO, and MgO.
Oil such as silicone oil may be added. Silicone oils include silicone oils such as dimethylpolysiloxane, diphenylpolysiloxane, and phenylmethylsiloxane; amino-modified polysiloxane, epoxy-modified polysiloxane, carboxyl-modified polysiloxane, carbinol-modified polysiloxane, methacryl-modified polysiloxane, mercapto-modified poly Reactive silicone oils such as siloxane and phenol-modified polysiloxane; cyclic dimethylcyclosiloxanes such as hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane and dodecamethylcyclohexasiloxane; 1,3,5- Trimethyl-1,3,5-triphenylcyclotrisiloxane, 1,3,5,7-tetramethyl-1,3,5,7-tetraphenylcyclo Cyclic methylphenylcyclosiloxanes such as trasiloxane, 1,3,5,7,9-pentamethyl-1,3,5,7,9-pentaphenylcyclopentasiloxane; cyclic phenylcyclosiloxanes such as hexaphenylcyclotrisiloxane Fluorine-containing cyclosiloxanes such as (3,3,3-trifluoropropyl) methylcyclotrisiloxane; hydrosilyl group-containing cyclosiloxanes such as methylhydrosiloxane mixtures, pentamethylcyclopentasiloxane, and phenylhydrocyclosiloxane; penta And vinyl group-containing cyclosiloxanes such as vinylpentamethylcyclopentasiloxane.

  Moreover, you may add a metal, a metal oxide, carbon black, etc. to a protective layer. Examples of the metal include aluminum, zinc, copper, chromium, nickel, silver and stainless steel, or those obtained by depositing these metals on the surface of plastic particles. Examples of the metal oxide include zinc oxide, titanium oxide, tin oxide, antimony oxide, indium oxide, bismuth oxide, indium oxide doped with tin, tin oxide doped with antimony and tantalum, and zirconium oxide doped with antimony. . These may be used alone or in combination of two or more. When two or more types are used in combination, they may be simply mixed, or may be in the form of a solid solution or fusion. The average particle size of the conductive particles is preferably 0.3 μm or less, particularly preferably 0.1 μm or less.

  The protective layer 2C may contain a curing catalyst for accelerating the curing of the guanamine compound and the melamine compound or the specific charge transport material. An acid catalyst is preferably used as the curing catalyst. Acid-based catalysts include acetic acid, chloroacetic acid, trichloroacetic acid, trifluoroacetic acid, oxalic acid, maleic acid, malonic acid, lactic acid and other aliphatic carboxylic acids, benzoic acid, phthalic acid, terephthalic acid, trimellitic acid, etc. Aromatic carboxylic acids, methane sulfonic acids, dodecyl sulfonic acids, benzene sulfonic acids, aliphatics such as dodecyl benzene sulfonic acids, naphthalene sulfonic acids, and aromatic sulfonic acids are used, but sulfur-containing materials should be used. desirable.

  The sulfur-containing material as the curing catalyst is desirably one that exhibits acidity at room temperature (for example, 25 ° C.) or after heating, and is most desirably at least one of organic sulfonic acids and derivatives thereof. The presence of these catalysts in the protective layer 2C is easily confirmed by energy dispersive X-ray analysis (EDS), X-ray photoelectron spectroscopy (XPS), or the like.

  Examples of the organic sulfonic acid and / or a derivative thereof include p-toluenesulfonic acid, dinonylnaphthalenesulfonic acid (DNNSA), dinonylnaphthalenedisulfonic acid (DNNDSA), dodecylbenzenesulfonic acid, and phenolsulfonic acid. Among these, p-toluenesulfonic acid and dodecylbenzenesulfonic acid are desirable. Moreover, as long as it can dissociate in a curable resin composition, you may use an organic sulfonate.

Further, a so-called thermal latent catalyst, which has a high catalytic ability when heated, may be used.
As a heat latent catalyst, for example, a microcapsule in which an organic sulfone compound or the like is encapsulated in a polymer form, an adsorbed acid or the like on a pore compound such as zeolite, and a proton acid and / or proton acid derivative is blocked with a base Thermal latent proton acid catalyst, proton acid and / or proton acid derivative esterified with primary or secondary alcohol, proton acid and / or proton acid derivative blocked with vinyl ethers and / or vinyl thioethers , Boron trifluoride monoethylamine complex, boron trifluoride pyridine complex, and the like.

Of these, a protonic acid and / or a protonic acid derivative blocked with a base is desirable.
As the protonic acid of the heat latent protonic acid catalyst, sulfuric acid, hydrochloric acid, acetic acid, formic acid, nitric acid, phosphoric acid, sulfonic acid, monocarboxylic acid, polycarboxylic acids, propionic acid, oxalic acid, benzoic acid, acrylic acid, methacrylic acid, Itaconic acid, phthalic acid, maleic acid, benzenesulfonic acid, o, m, p-toluenesulfonic acid, styrenesulfonic acid, dinonylnaphthalenesulfonic acid, dinonylnaphthalenedisulfonic acid, decylbenzenesulfonic acid, undecylbenzenesulfonic acid, Examples include tridecylbenzenesulfonic acid, tetradecylbenzenesulfonic acid, dodecylbenzenesulfonic acid and the like. In addition, as protonic acid derivatives, neutralized products such as alkali metal salts of alkaline acids or alkaline earth metal circles such as sulfonic acid and phosphoric acid, and polymer compounds in which a protonic acid skeleton is introduced into the polymer chain (polyvinylsulfone) Acid, etc.). Examples of the base that blocks the protonic acid include amines.

  Amines are classified as primary, secondary or tertiary amines. There is no restriction in particular and any of them may be used.

  Examples of the primary amine include methylamine, ethylamine, propylamine, isopropylamine, n-butylamine, isobutylamine, t-butylamine, hexylamine, 2-ethylhexylamine, secondary butylamine, allylamine, and methylhexylamine.

  As secondary amines, dimethylamine, diethylamine, di-n-propylamine, diisopropylamine, di-n-butylamine, diisobutylamine, di-t-butylamine, dihexylamine, di (2-ethylhexyl) amine, N-isopropyl N-isobutylamine , Di (2-ethylhexyl) amine, disecondary butylamine, diallylamine, N-methylhexylamine, 3-pipecoline, 4-pipecoline, 2,4-lupetidine, 2,6-lupetidine, 3,5-lupetidine, morpholine, N -Methylbenzylamine and the like.

  As tertiary amines, trimethylamine, triethylamine, tri-n-propylamine, triisopropylamine, tri-n-butylamine, triisobutylamine, tri-t-butylamine, trihexylamine, tri (2-ethylhexyl) amine, N-methylmorpholine, N, N-dimethylallylamine, N-methyldiallylamine, triallylamine, N, N-dimethylallylamine, N, N, N ′, N′-tetramethyl-1,2-diaminoethane, N, N, N ′, N '-Tetramethyl-1,3-diaminopropane, N, N, N', N'-tetraallyl-1,4-diaminobutane, N-methylpiperidine, pyridine, 4-ethylpyridine, N-propyldiallylamine, 3- Dimethylaminopropanol, 2-ethylpyrazine, 2,3-di Tilpyrazine, 2,5-dimethylpyrazine, 2,4-lutidine, 2,5-lutidine, 3,4-lutidine, 3,5-lutidine, 2,4,6-collidine, 2-methyl-4-ethylpyridine, 2-methyl-5-ethylpyridine, N, N, N ′, N′-tetramethylhexamethylenediamine, N-ethyl-3-hydroxypiperidine, 3-methyl-4-ethylpyridine, 3-ethyl-4-methyl Pyridine, 4- (5-nonyl) pyridine, imidazole, N-methylpiperazine and the like can be mentioned.

Commercially available products include “NACURE2501” (toluenesulfonic acid dissociation, methanol / isopropanol solvent, pH 6.0 to pH 7.2, dissociation temperature 80 ° C.), “NACURE2107” (p-toluenesulfonic acid dissociation, manufactured by King Industries, Inc. Isopropanol solvent, pH 8.0 to pH 9.0, dissociation temperature 90 ° C.) “NACURE 2500” (p-toluenesulfonic acid dissociation, isopropanol solvent, pH 6.0 to pH 7.0, dissociation temperature 65 ° C.), “NACURE 2530” (P-toluenesulfonic acid dissociation, methanol / isopropanol solvent, pH 5.7 to pH 6.5, dissociation temperature 65 ° C.), “NACURE2547” (p-toluenesulfonic acid dissociation, aqueous solution, pH 8.0 to pH 9.0, Dissociation temperature 107 ), “NACURE2558” (p-toluenesulfonic acid dissociation, ethylene glycol solvent, pH 3.5 to pH4.5, dissociation temperature 80 ° C.), “NACUREXP-357” (p-toluenesulfonic acid dissociation, methanol solvent, pH 2. 0 to pH 4.0, dissociation temperature 65 ° C.) “NACUREXP-386” (p-toluenesulfonic acid dissociation, aqueous solution, pH 6.1 to pH 6.4, dissociation temperature 80 ° C.), “NACUREX C-2211” (p -Toluenesulfonic acid dissociation, pH 7.2 to pH 8.5, dissociation temperature 80 ° C.), “NACURE 5225” (dodecylbenzenesulfonic acid dissociation, isopropanol solvent, pH 6.0 to pH 7.0, dissociation temperature 120 ° C.), “ NACURE 5414 "(dodecylbenzenesulfonic acid dissociation, key Ren solvent, dissociation temperature 120 ° C.), “NACURE 5528” (dodecylbenzenesulfonic acid dissociation, isopropanol solvent, pH 7.0 to pH 8.0, dissociation temperature 120 ° C.), “NACURE 5925” (dodecylbenzenesulfonic acid dissociation, pH 7.0) PH 7.5 or less, dissociation temperature 130 ° C., “NACURE 1323” (disinyl naphthalene sulfonic acid dissociation, xylene solvent, pH 6.8 to pH 7.5, dissociation temperature 150 ° C.), “NACURE 1419” (dinonyl naphthalene sulfonic acid Dissociation, xylene / methyl isobutyl ketone solvent, dissociation temperature 150 ° C.), “NACURE1557” (dinonylnaphthalenesulfonic acid dissociation, butanol / 2-butoxyethanol solvent, pH 6.5 to pH 7.5, dissociation temperature 150 ° C.), “ NA CUREX 49-110 ”(dinonyl naphthalene disulfonic acid dissociation, isobutanol / isopropanol solvent, pH 6.5 to pH 7.5, dissociation temperature 90 ° C.),“ NACURE 3525 ”(dinonyl naphthalene disulfonic acid dissociation, isobutanol / isopropanol solvent, pH 7.0 to pH 8.5, dissociation temperature 120 ° C., “NACUREXP-383” (dinonyl naphthalene disulfonic acid dissociation, xylene solvent, dissociation temperature 120 ° C.), “NACURE 3327” (dinonyl naphthalene disulfonic acid dissociation, isobutanol / Isopropanol solvent, pH 6.5 to pH 7.5, dissociation temperature 150 ° C.), “NACURE4167” (phosphoric acid dissociation, isopropanol / isobutanol solvent, pH 6.8 to pH 7.3, dissociation temperature 80 ), “NACUREXP-297” (phosphoric acid dissociation, water / isopropanol solvent, pH 6.5 to pH 7.5, dissociation temperature 90 ° C., “NACURE 4575” (phosphoric acid dissociation, pH 7.0 to pH 8.0, dissociation temperature) 110 ° C.).
These thermal latent catalysts may be used alone or in combination of two or more.

  Here, the compounding amount of the catalyst is in the range of 0.1% by mass or more and 10% by mass or less with respect to the total solid content excluding the fluororesin particles and the fluorinated alkyl group-containing copolymer in the coating solution. Desirably, 0.1 mass% or more and 5 mass% or less are especially desirable.

(Method for forming surface layer)
Here, as an example of the step of forming the surface layer in the production of the photoreceptor in the present embodiment, a method of forming the protective layer 2C that is the surface layer in the photoreceptor of the first aspect will be described.
First, in the method for producing the photoreceptor of the first aspect, the conductive substrate 1 in which layers other than the surface layer (that is, the protective layer 2C) (that is, the undercoat layer 4, the charge generation layer 2A, the charge transport layer 2B, and the like) are formed. And a coating solution containing the specific charge transport material and other composition is applied onto the conductive substrate and polymerized to form a surface layer (ie, protective layer 2C). Forming a surface layer.

  Examples of the solvent used for forming the protective layer 2C as the surface layer include cycloaliphatic ketone compounds such as cyclobutanone, cyclopentanone, cyclohexanone, and cycloheptanone; methanol, ethanol, propanol, butanol, cyclopentanol, and the like. Cyclic or linear alcohols; Linear ketones such as acetone and methyl ethyl ketone; Cyclic or linear ethers such as tetrahydrofuran, dioxane, ethylene glycol, and diethyl ether; Halogenated fats such as methylene chloride, chloroform, and ethylene chloride And solvents such as group hydrocarbon solvents.

  As a coating method of the film forming coating solution for forming the protective layer 2C as the surface layer, push-up coating method, ring coating method, blade coating method, Meyer bar coating method, spray coating method, dip coating method, bead Examples of the method include a coating method, an air knife coating method, a curtain coating method, and an inkjet coating method. After coating, for example, the protective layer 2C can be obtained by heating at a temperature of 100 ° C. to 170 ° C. and curing (crosslinking).

  In the present embodiment, the thickness of the surface layer is preferably 5 μm or more and 20 μm or less, more preferably 7 μm or more and 15 μm or less.

[Photoreceptor of Second Embodiment: Surface Layer = Charge Transport Layer]
As shown in FIG. 2, the photoreceptor of the second mode, which is an example in the present embodiment, is a layer in which an undercoat layer 4, a charge generation layer 2A, and a charge transport layer 2B are laminated in this order on a conductive substrate 1. The charge transport layer 2B is a surface layer.

  As the conductive substrate 1, the undercoat layer 4, and the charge generation layer 2A in the photoreceptor of the second embodiment, the conductive substrate 1, the undercoat layer 4, the charge in the photoreceptor of the first embodiment shown in FIG. The generation layer 2A is applied as it is. As the charge transport layer 2B in the photoconductor of the second mode, the protective layer 2C in the photoconductor of the first mode shown in FIG. 1 is applied as it is.

[Image forming apparatus]
FIG. 3 is a schematic configuration diagram illustrating the image forming apparatus according to the present embodiment. As shown in FIG. 3, the image forming apparatus 100 includes a process cartridge 300 including an electrophotographic photosensitive member 7, an exposure device 9, a transfer device 40, and an intermediate transfer member 50. In the image forming apparatus 100, the exposure device 9 is disposed at a position where the electrophotographic photosensitive member 7 can be exposed from the opening of the process cartridge 300, and the transfer device 40 is interposed between the electrophotographic photosensitive member via the intermediate transfer member 50. 7, and a part of the intermediate transfer member 50 is disposed in contact with the electrophotographic photosensitive member 7.

  A process cartridge 300 in FIG. 3 integrally supports an electrophotographic photosensitive member 7, a charging device 8, a developing device 11, and a cleaning device 13 in a housing. The cleaning device 13 has a cleaning blade 131 (blade member) made of an elastic material such as rubber, and the cleaning blade 131 is arranged so that the edge of one end thereof is in contact with the surface of the electrophotographic photosensitive member 7. A method of removing a developer such as toner adhered to the surface of the photographic photoreceptor 7 is applied. In addition to this, a known cleaning method such as a method using a cleaning brush using conductive plastic is used.

  Further, an example is shown in which a fibrous member 132 (roll shape) for supplying the lubricant 14 to the surface of the photoreceptor 7 and a fibrous member 133 (flat brush shape) for assisting cleaning are used. It may be used accordingly.

  As the charging device 8, for example, a contact type charger using a conductive or semiconductive charging roller, a charging brush, a charging film, a charging rubber blade, a charging tube or the like is used. Further, a non-contact type roller charger, a known charger such as a scorotron charger using a corona discharge or a corotron charger may be used.

  Although not shown, a photosensitive member heating member for raising the temperature of the electrophotographic photosensitive member 7 and reducing the relative temperature may be provided around the electrophotographic photosensitive member 7.

  Examples of the exposure apparatus 9 include optical system devices that expose the surface of the photoconductor 7 with light such as semiconductor laser light, LED light, and liquid crystal shutter light in a desired image-like manner. The wavelength of the light source is in the spectral sensitivity region of the photoreceptor. As the wavelength of the semiconductor laser, near infrared having an oscillation wavelength near 780 nm is the mainstream. However, the present invention is not limited to this wavelength, and a laser having an oscillation wavelength of 600 nm or a laser having an oscillation wavelength of 400 nm to 450 nm as a blue laser may be used. In addition, a surface-emitting type laser light source that can output a multi-beam is also effective for forming a multicolor image.

  As the developing device 11, for example, a general developing device that performs development by bringing a magnetic or non-magnetic one-component developer or two-component developer into contact or non-contact with each other may be used. The developing device is not particularly limited as long as it has the functions described above, and is selected according to the purpose. For example, a known developing device having a function of adhering the one-component developer or the two-component developer to the photoreceptor 7 using a brush, a roller, or the like can be used. Among these, those using a developing roller holding the developer on the surface are desirable.

Hereinafter, the toner used in the developing device 11 will be described.
The toner used in the image forming apparatus of this embodiment has an average shape factor ((ML ² / A) × (π / 4) × 100, where ML represents the maximum length of the particles, and A represents the projected area of the particles. Is preferably from 100 to 150, more preferably from 105 to 145, and even more preferably from 110 to 140. Further, the toner preferably has a volume average particle size of 3 μm to 12 μm, and more preferably 3.5 μm to 9 μm.

  The toner is not particularly limited by the production method. For example, a kneading and pulverizing method in which a binder resin, a colorant and a release agent, and a charge control agent are further added, kneaded, pulverized, and classified; A method of changing the shape of particles obtained by the method by mechanical impact force or thermal energy; a dispersion monomer formed by emulsion polymerization of a polymerizable monomer of a binder resin, a colorant and a release agent In addition, an emulsion polymerization aggregation method for obtaining toner particles by mixing a dispersion liquid such as a charge control agent and aggregating and heat-fusing to obtain toner particles; a polymerizable monomer for obtaining a binder resin, a colorant and a release agent Suspension polymerization method in which a solution of an agent, a charge control agent, etc. is suspended in an aqueous solvent for polymerization; a binder resin, a coloring agent, a release agent, and a solution of a charge control agent, etc., in an aqueous solvent Toner produced by the suspension method, etc. It is use.

  Further, a known method such as a production method in which the toner obtained by the above method is used as a core, and agglomerated particles are further adhered and heated and fused to give a core-shell structure is used. The toner production method is preferably a suspension polymerization method, an emulsion polymerization aggregation method, or a dissolution suspension method in which an aqueous solvent is used from the viewpoint of shape control and particle size distribution control, and an emulsion polymerization aggregation method is particularly desirable.

  The toner base particles desirably contain a binder resin, a colorant, and a release agent, and may further contain silica or a charge control agent.

  Binder resins used for toner base particles include styrenes such as styrene and chlorostyrene, monoolefins such as ethylene, propylene, butylene and isoprene, vinyl acetate, vinyl propionate, vinyl benzoate, vinyl butyrate, etc. Α-methylene aliphatics such as vinyl esters, methyl acrylate, ethyl acrylate, butyl acrylate, dodecyl acrylate, octyl acrylate, phenyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, dodecyl methacrylate Homopolymers and copolymers of monocarboxylic acid esters, vinyl ethers such as vinyl methyl ether, vinyl ethyl ether and vinyl butyl ether, vinyl ketones such as vinyl methyl ketone, vinyl hexyl ketone and vinyl isopropenyl ketone , Polyester resins by copolymerization of dicarboxylic acids and diols.

  Particularly representative binder resins include polystyrene, styrene-alkyl acrylate copolymer, styrene-alkyl methacrylate copolymer, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer. A polymer, polyethylene, a polypropylene, a polyester resin etc. are mentioned. Further, polyurethane, epoxy resin, silicone resin, polyamide, modified rosin, paraffin wax and the like can be mentioned.

  In addition, as colorants, magnetic powders such as magnetite and ferrite, carbon black, aniline blue, caryl blue, chrome yellow, ultramarine blue, Dupont oil red, quinoline yellow, methylene blue chloride, phthalocyanine blue, malachite green oxalate, Lamp Black, Rose Bengal, C.I. I. Pigment red 48: 1, C.I. I. Pigment red 122, C.I. I. Pigment red 57: 1, C.I. I. Pigment yellow 97, C.I. I. Pigment yellow 17, C.I. I. Pigment blue 15: 1, C.I. I. Pigment Blue 15: 3 is exemplified as a representative example.

  Typical examples of the release agent include low molecular weight polyethylene, low molecular weight polypropylene, Fischer tropical wax, montan wax, carnauba wax, rice wax, and candelilla wax.

  As the charge control agent, known ones are used, and azo metal complex compounds, metal complex compounds of salicylic acid, and resin type charge control agents containing polar groups are used. When toner is manufactured by a wet manufacturing method, it is desirable to use a material that is difficult to dissolve in water. The toner may be either a magnetic toner containing a magnetic material or a non-magnetic toner containing no magnetic material.

  The toner used in the developing device 11 is manufactured by mixing the toner base particles and the external additive with a Henschel mixer or a V blender. Further, when the toner base particles are produced by a wet method, they may be externally added by a wet method.

  Lubricating particles may be added to the toner used in the developing device 11. Lubricating particles include solid lubricants such as graphite, molybdenum disulfide, talc, fatty acids and fatty acid metal salts, low molecular weight polyolefins such as polypropylene, polyethylene and polybutene, silicones having a softening point upon heating, oleic amides , Erucic acid amide, ricinoleic acid amide, stearic acid amide and other aliphatic amides, carnauba wax, rice wax, candelilla wax, tree wax, jojoba oil and other plant waxes, beeswax animal wax, montan wax, ozokerite , Ceresin, paraffin wax, microcrystalline wax, minerals such as Fischer-Tropsch wax, petroleum wax, and modified products thereof. These are used individually by 1 type or in combination of 2 or more types. However, the average particle size is preferably in the range of 0.1 μm or more and 10 μm or less, and those having the above chemical structure may be pulverized to make the particle sizes uniform. The amount added to the toner is desirably in the range of 0.05% by mass to 2.0% by mass, and more desirably in the range of 0.1% by mass to 1.5% by mass.

  To the toner used in the developing device 11, inorganic particles, organic particles, composite particles obtained by attaching inorganic particles to the organic particles, or the like may be added.

  Inorganic particles include silica, alumina, titania, zirconia, barium titanate, aluminum titanate, strontium titanate, magnesium titanate, zinc oxide, chromium oxide, cerium oxide, antimony oxide, tungsten oxide, tin oxide, tellurium oxide, Various inorganic oxides such as manganese oxide, boron oxide, silicon carbide, boron carbide, titanium carbide, silicon nitride, titanium nitride, and boron nitride, nitrides, borides, and the like are preferably used.

  In addition, the inorganic particles may be mixed with titanium coupling agents such as tetrabutyl titanate, tetraoctyl titanate, isopropyl triisostearoyl titanate, isopropyl tridecylbenzenesulfonyl titanate, bis (dioctylpyrophosphate) oxyacetate titanate, γ- (2- Aminoethyl) aminopropyltrimethoxysilane, γ- (2-aminoethyl) aminopropylmethyldimethoxysilane, γ-methacryloxypropyltrimethoxysilane, N-β- (N-vinylbenzylaminoethyl) γ-aminopropyltrimethoxy Silane hydrochloride, hexamethyldisilazane, methyltrimethoxysilane, butyltrimethoxysilane, isobutyltrimethoxysilane, hexyltrimethoxysilane, octyltrimethoxysilane The treatment may be performed with a silane coupling agent such as run, decyltrimethoxysilane, dodecyltrimethoxysilane, phenyltrimethoxysilane, o-methylphenyltrimethoxysilane, and p-methylphenyltrimethoxysilane. In addition, those hydrophobized with higher fatty acid metal salts such as silicone oil, aluminum stearate, zinc stearate, calcium stearate and the like are also desirably used.

  Examples of the organic particles include styrene resin particles, styrene acrylic resin particles, polyester resin particles, and urethane resin particles.

  The particle diameter is preferably 5 nm to 1000 nm, more preferably 5 nm to 800 nm, and even more preferably 5 nm to 700 nm in terms of number average particle diameter. Moreover, it is desirable that the sum of the addition amounts of the above-described particles and the lubricating particles is 0.6% by mass or more.

  As the other inorganic oxide added to the toner, it is desirable to use a small-diameter inorganic oxide having a primary particle size of 40 nm or less, and further add an inorganic oxide having a larger diameter. Known inorganic oxide particles are used, but it is desirable to use silica and titanium oxide in combination.

  Moreover, you may surface-treat about a small diameter inorganic particle. Furthermore, it is also desirable to add carbonates such as calcium carbonate and magnesium carbonate and inorganic minerals such as hydrotalcite.

  In addition, the color toner for electrophotography is used by mixing with a carrier. As the carrier, iron powder, glass beads, ferrite powder, nickel powder, or those coated with a resin are used. The mixing ratio with the carrier is set as necessary.

  As the transfer device 40, for example, a contact transfer charger using a belt, a roller, a film, a rubber blade, etc., or a known transfer charger such as a scorotron transfer charger using a corona discharge or a corotron transfer charger. Can be mentioned.

  As the intermediate transfer member 50, a belt-like member (intermediate transfer belt) made of polyimide, polyamideimide, polycarbonate, polyarylate, polyester, rubber or the like having semiconductivity is used. Further, as the form of the intermediate transfer member 50, a drum-like one is used in addition to the belt shape.

  In addition to the above-described devices, the image forming apparatus 100 may include, for example, a light neutralizing device that performs light neutralization on the photoconductor 7.

  FIG. 4 is a schematic cross-sectional view showing an image forming apparatus according to another embodiment. As shown in FIG. 4, the image forming apparatus 120 is a tandem-type full 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 member 50, and one electrophotographic photosensitive member is used for one color. The image forming apparatus 120 has the same configuration as the image forming apparatus 100 except that it is a tandem system.

  EXAMPLES Hereinafter, although this invention is demonstrated further more concretely based on an Example and a comparative example, this invention is not limited to a following example at all. In the following, “part” is based on mass unless otherwise specified.

[Example 1]
(Formation of undercoat layer)
100 parts of zinc oxide (average particle size 70 nm: manufactured by Teika: specific surface area value 15 m ² / g) is stirred and mixed with 500 parts of tetrahydrofuran, and 1.3 parts of a silane coupling agent (KBM503: manufactured by Shin-Etsu Chemical Co., Ltd.) is added. Stir for 2 hours. Thereafter, toluene was distilled off under reduced pressure and baked at 120 ° C. for 3 hours to obtain a silane coupling agent surface-treated zinc oxide.
110 parts of the surface-treated zinc oxide was stirred and mixed with 500 parts of tetrahydrofuran, a solution prepared by dissolving 0.6 part of alizarin in 50 parts of tetrahydrofuran was added, and the mixture was stirred at 50 ° C. for 5 hours. Then, the zinc oxide to which alizarin was imparted by filtration under reduced pressure was filtered off, and further dried at 60 ° C. under reduced pressure to obtain alizarin imparted zinc oxide.
60 parts of this alizarin-provided zinc oxide, 13.5 parts of a curing agent (blocked isocyanate Sumijoule 3175, manufactured by Sumitomo Bayern Urethane Co., Ltd.) and 15 parts of butyral resin (ESREC BM-1, manufactured by Sekisui Chemical Co., Ltd.) in 85 parts of methyl ethyl ketone 38 parts of the dissolved solution and 25 parts of methyl ethyl ketone were mixed and dispersed with a sand mill for 2 hours using 1 mmφ glass beads to obtain a dispersion.
As a catalyst, 0.005 part of dioctyltin dilaurate and 40 parts of silicone resin particles (Tospearl 145, manufactured by GE Toshiba Silicone) were added to the resulting dispersion to obtain a coating solution for an undercoat layer. This coating solution was applied on an aluminum substrate having a diameter of 60 mm, a length of 357 mm, and a thickness of 1 mm by a dip coating method, followed by drying and curing at 170 ° C. for 40 minutes to obtain an undercoat layer having a thickness of 19 μm.

(Formation of charge generation layer)
Bragg angles (2θ ± 0.2 °) of X-ray diffraction spectrum using Cukα characteristic X-ray as a charge generating material are at least 7.3 °, 16.0 °, 24.9 °, 28.0 ° A mixture of 15 parts of hydroxygallium phthalocyanine having a diffraction peak, 10 parts of vinyl chloride / vinyl acetate copolymer resin (VMCH, manufactured by Nihon Unicar) as a binder resin, and 200 parts of n-butyl acetate was used. The glass beads were used for dispersion for 4 hours in a sand mill. To the obtained dispersion, 175 parts of n-butyl acetate and 180 parts of methyl ethyl ketone were added and stirred to obtain a charge generation layer coating solution. This charge generation layer coating solution was dip coated on the undercoat layer and dried at room temperature (25 ° C.) to form a charge generation layer having a thickness of 0.2 μm.

(Formation of charge transport layer)
N, N′-diphenyl-N, N′-bis (3-methylphenyl)-[1,1 ′] biphenyl-4,4′-diamine 42 parts and bisphenol Z polycarbonate resin (viscosity average molecular weight: 50,000) 58 Part was added to 800 parts of chlorobenzene and dissolved to obtain a coating solution for charge transport layer. This coating solution was applied onto the charge generation layer and dried at 150 ° C. for 45 minutes to form the charge transport layer. The film thickness at this time was measured with an interference film thickness meter and found to be 19.78 μm.

(Formation of surface protective layer)
96 parts of the following (compound α) (corresponding to the compound represented by the above-mentioned “I-11”) as a charge transporting substance (A) having a plurality of hydroxyl groups, a charge transporting substance having no reactive substituent (B ) (Compound II) (corresponding to the compound represented by the above-mentioned “B-8”) 0.19 parts, melamine resin (corresponding to the compound represented by the above-mentioned “(B) -2”) 5 parts, 0.05 parts of dodecylbenzenesulfonic acid, 0.26 parts of leveling agent BYK-302 (manufactured by Big Chemie Japan Co., Ltd.) and 160 parts of cyclopentanol were added to prepare a coating solution for a protective layer. This coating solution is applied onto the charge transport layer by a dip coating method, air-dried at room temperature (25 ° C.) for 10 minutes, and then heated and cured at 155 ° C. for 45 minutes to form a protective layer having a thickness of 6.0 μm. Thus, a photoreceptor was produced.

-Evaluation-
The residual potential of the obtained photoreceptor was measured / evaluated as follows.
<Humidity fluctuation RP>
Under the environment of room temperature and low humidity (20 ° C., 15%) and room temperature and high humidity (20 ° C., 85%), the photoconductor was charged at −700 V with a scorotron charger while rotating the photoconductor at 100 rpm. After 423 msec after charging, 5080.0 erg / cm ² of red LED light was applied to neutralize the charge, and the potential VRP after 92 msec from neutralization was measured using a surface potential measurement probe: Trek 334 (manufactured by Trek). Was the residual potential (RP).
At this time, the difference in residual potential (RP) between the room temperature and low humidity environment and the room temperature and high humidity environment was evaluated as “humidity fluctuation RP”, and 5V or less was evaluated as “◯”, and those exceeding 5 V were evaluated as “×”. .

<Cycle fluctuation RP>
In a high temperature and high humidity (28 ° C., 85%) environment, the photoconductor was rotated at 100 rpm, the photoconductor was charged to −700 V by a scorotron charger, and 5080.0 erg / cm ² after 423 msec after charging. Then, the potential VRP after 92 msec from the static elimination was measured using a surface potential measurement probe: Trek 334 (manufactured by Trek), and this was defined as the initial residual potential (RP). Then, this measurement cycle was repeated 800 cyc, and the residual potential (RP) after 800 cyc was measured.
At this time, the difference between the initial residual potential (RP) and the residual potential (RP) after 800 cyc is defined as “cycle fluctuation RP”, the absolute value of the difference being “50” or less is “◯”, and the absolute value of the difference is Those exceeding 50V were evaluated as “x”.
The results are shown in Table 2.

[Examples 2-6, Comparative Examples 1-9]
In Example 1, “charge transporting substance (A) having a plurality of hydroxyl groups” and “charge transporting substance (B) having no reactive substituent” used for the surface protective layer are those shown in Table 1 below. Implemented except that the ratio of the charge transport material (B) to the total amount of the charge transport materials (A) and (B) (content ratio of the charge transport material (B)) was changed to the one shown in Table 2 below. Photoconductors were prepared by the method described in Example 1 and evaluated.

DESCRIPTION OF SYMBOLS 1 Substrate, 2 Photosensitive layer, 2A Charge generation layer, 2B Charge transport layer, 2C Protective layer, 4 Undercoat layer, 7 Electrophotographic photoreceptor, 8 Charging device, 9 Exposure device, 11 Developing device, 13 Cleaning device, 14 Lubrication 40, transfer device, 50 intermediate transfer member, 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 (3)

A conductive substrate and a photosensitive layer on the conductive substrate;
The layer constituting the outermost surface of the photosensitive layer contains a charge transport material (A) having a plurality of hydroxyl groups and a charge transport material (B) having no reactive substituent,
The ratio of the charge transport material (B) in the total charge transport material is 0.19% by mass or more and 1.5% by mass or less,
An electrophotographic photoreceptor in which the ionization potential (IpA) of the charge transport material (A) and the ionization potential (IpB) of the charge transport material (B) satisfy the following formula (1).
IpB + 0.2 [eV] ≧ IpA [eV] ≧ IpB + 0.04 [eV] Equation (1) A charge transport material having a photosensitive layer on a conductive substrate, wherein the layer constituting the outermost surface of the photosensitive layer does not have a reactive substituent with the polymer of the charge transport material (A) having a plurality of hydroxyl groups (B), the ratio of the charge transport material (B) in the total charge transport material is 0.19 mass% or more and 1.5 mass% or less, and the ionization potential of the charge transport material (A) ( An electrophotographic photoreceptor in which IpA) and the ionization potential (IpB) of the charge transport material (B) satisfy the following formula (1):
A charging device for charging the surface of the electrophotographic photosensitive member;
An electrostatic latent image forming apparatus for forming an electrostatic latent image on the surface of the charged electrophotographic photosensitive member;
A developing device for developing the electrostatic latent image with a developer to form a toner image;
A transfer device for transferring the toner image to a transfer medium;
An image forming apparatus comprising:
IpB + 0.2 [eV] ≧ IpA [eV] ≧ IpB + 0.04 [eV] Equation (1) A charge transport material having a photosensitive layer on a conductive substrate, wherein the layer constituting the outermost surface of the photosensitive layer does not have a reactive substituent with the polymer of the charge transport material (A) having a plurality of hydroxyl groups (B), the ratio of the charge transport material (B) in the total charge transport material is 0.19 mass% or more and 1.5 mass% or less, and the ionization potential of the charge transport material (A) ( An electrophotographic photoreceptor in which IpA) and the ionization potential (IpB) of the charge transport material (B) satisfy the following formula (1):
A process cartridge that can be attached to and detached from an image forming apparatus.
IpB + 0.2 [eV] ≧ IpA [eV] ≧ IpB + 0.04 [eV] Equation (1)