JP2016066062A - Electrophotographic photoreceptor, process cartridge, and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrophotographic photoreceptor that has suppressed the generation of cracks in a photosensitive layer.SOLUTION: There is provided an electrophotographic photoreceptor including a conductive substrate, and a single-layer photosensitive layer that is provided on the conductive substrate, the photosensitive layer containing a binder resin, a charge generating material, a hole transport material, and an electron transport material represented by the following general formula (I), and having an elastic deformation ratio R of 0.340 or more and 0.360 or less.SELECTED DRAWING: None

Description

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

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

For example, Patent Document 1 discloses “a diphenoquinone compound represented by a specific formula contained in a photosensitive layer as a charge transport material.”
Patent Document 2 discloses “a naphthalenedicarboxylic imide compound represented by a specific formula as an electron-transporting acceptor compound that can be used for an electrophotographic photoreceptor”.
Patent Document 3 discloses “a naphthalenedicarboxylic acid diimide compound represented by a specific formula as an electron-transporting acceptor compound that can be used for an electrophotographic photoreceptor”.
Patent Document 4 discloses “an electrophotographic photoreceptor in which the photosensitive layer contains a fluorene compound represented by a specific formula”.

  In Patent Document 5, “a photoconductive imaging member including a support base and a single layer on the support base, the single layer includes a mixture of a light generating component, a charge transport component, an electron transport component, and a binder. And a photoconductive imaging member characterized in that the electron transport component contains a 2-ethylhexanol derivative of (4-carbonyl-9-fluorenylidene) malononitrile represented by a specific formula. " .

  Patent Document 6 discloses that an electron having a single-layer type photosensitive layer containing at least a resin binder, a charge generating material, a hole transporting material, and an electron transporting material on a conductive substrate directly or via an undercoat layer. In the photographic photoreceptor, an electrophotographic photoreceptor characterized in that the photosensitive layer contains a biphenyl derivative.

  Patent Document 7 states that “a photosensitive layer is formed on a conductive substrate, the photosensitive layer is a phthalocyanine compound as a charge generating agent, and at least one compound represented by a specific formula as an electron transporting agent and a terphenyl compound. A positively charged single-layer type electrophotographic photosensitive member characterized in that it contains:

  Patent Document 8 discloses that “a conductive substrate and a single-layer type photosensitive layer provided on the conductive substrate, at least selected from a binder resin, a hydroxygallium phthalocyanine pigment, and a chlorogallium phthalocyanine pigment”. An electrophotographic photoreceptor having a photosensitive layer comprising one kind of charge generation material, a hole transport material represented by a specific formula, and an electron transport material represented by a specific formula. Is disclosed.

JP-A-4-285670 Japanese Patent Laid-Open No. 5-25136 Japanese Patent Laid-Open No. 5-25174 JP 9-43876 A JP 2005-215679 A JP 2000-314969 A JP 2001-242656 A JP 2013-231867 A

  An object of the present invention is to provide an electrophotographic photoreceptor having a single-layer type photosensitive layer containing a binder resin, a charge generation material, a hole transport material, and an electron transport material represented by the general formula (I). It is an object of the present invention to provide an electrophotographic photosensitive member in which cracking of the photosensitive layer is suppressed as compared with a case where the elastic deformation rate R of the photosensitive layer is less than 0.340.

The above problem is solved by the following means. That is,
The invention according to claim 1
A conductive substrate;
A single-layer type photosensitive layer provided on the conductive substrate, comprising a binder resin, a charge generation material, a hole transport material, an electron transport material represented by the following general formula (I), A photosensitive layer having an elastic deformation rate R of 0.340 or more and 0.360 or less,
An electrophotographic photosensitive member having:

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

The invention according to claim 2
The electrophotographic photosensitive member according to claim 1, wherein the photosensitive layer is provided as an outermost surface layer, and the Young's modulus E of the photosensitive layer is 4.40 GPa or more.

The invention according to claim 3
The electrophotographic photosensitive member according to claim 1, wherein R ¹⁸ in the general formula (1) is an aryl group or an aralkyl group.

The invention according to claim 4
4. The electrophotographic photosensitive member according to claim 1, wherein a content of the electron transport material with respect to the binder resin is 6% by mass or more and 34% by mass or less.

The invention according to claim 5
The electrophotographic photosensitive member according to any one of claims 1 to 4, comprising:
A process cartridge that can be attached to and detached from an image forming apparatus.

The invention according to claim 6
The electrophotographic photosensitive member according to any one of claims 1 to 4,
Charging means for charging the surface of the electrophotographic photosensitive member;
An electrostatic latent image forming means for forming an electrostatic latent image on the surface of the charged electrophotographic photosensitive member;
Developing means for developing the electrostatic latent image formed on the surface of the electrophotographic photosensitive member with a developer containing toner to form a toner image;
Transfer means for transferring the toner image to the surface of the recording medium;
An image forming apparatus comprising:

The invention according to claim 7 provides:
The image forming apparatus according to claim 6, wherein the transfer unit is a transfer unit that directly transfers the toner image onto the surface of the recording medium.

  According to the first aspect of the invention, an electron having a single-layer type photosensitive layer including a binder resin, a charge generation material, a hole transport material, and an electron transport material represented by the general formula (I) In the photographic photoreceptor, an electrophotographic photoreceptor is provided in which the occurrence of cracking of the photosensitive layer is suppressed as compared with the case where the elastic deformation rate R of the photosensitive layer is less than 0.340.

  According to the second aspect of the present invention, compared to the case where the Young's modulus E of the photosensitive layer is less than 4.40 GPa, the electrophotographic photosensitive member in which the occurrence of cracking of the photosensitive layer and the filming of the recording medium component on the photosensitive layer are suppressed The body is provided.

According to the invention of claim 3, in the electron transport material represented by the general formula (I), the occurrence of cracking of the photosensitive layer and the recording medium component in the photosensitive layer are compared with the case where R ¹⁸ is an alkyl group. An electrophotographic photosensitive member in which filming is suppressed is provided.

According to the fourth aspect of the present invention, there is provided an electrophotographic photosensitive member in which the occurrence of cracks in the photosensitive layer is suppressed as compared with the case where the content of the electron transport material with respect to the binder resin exceeds 34% by mass.
In addition, an electrophotographic photosensitive member is provided in which filming of the recording medium component on the photosensitive layer is suppressed as compared with a case where the content of the electron transport material with respect to the binder resin is less than 6% by mass.

  According to the invention according to claim 5, 6 or 7, a monolayer type photosensitive material including a binder resin, a charge generation material, a hole transport material, and an electron transport material represented by the general formula (I). In the electrophotographic photosensitive member having a layer, a process cartridge in which cracking of the photosensitive layer of the electrophotographic photosensitive member is suppressed compared to the case where an electrophotographic photosensitive member having an elastic deformation rate R of less than 0.340 is applied, Alternatively, an image forming apparatus is provided.

1 is a schematic partial cross-sectional view showing an electrophotographic photosensitive member according to the present 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 image forming apparatus which concerns on other embodiment.

  Embodiments that are examples of the present invention will be described below.

[Electrophotographic photoreceptor]
The electrophotographic photoreceptor according to the exemplary embodiment is a positively charged organic photoreceptor that includes a conductive substrate and has a single-layer type photosensitive layer on the conductive substrate.
The single-layer type photosensitive layer is referred to as a binder resin, a charge generation material, a hole transport material, and an electron transport material represented by the general formula (I) (hereinafter referred to as “specific electron transport material”). And). The elastic deformation rate R of the photosensitive layer is 0.340 or more and 0.360 or less.
The single-layer type photosensitive layer is a photosensitive layer having hole transporting properties and electron transporting properties as well as charge generation ability.

Here, the single-layer electrophotographic photosensitive member contains a charge generation material, a hole transport material, and an electron transport material in the photosensitive layer. For this reason, a single layer type electrophotographic photoreceptor (hereinafter sometimes simply referred to as “photoreceptor”) is more likely to have microscopic compositional non-uniformity in the photosensitive layer than a laminated photoreceptor. . In an image forming process, when a pressure (for example, dynamic pressure) is repeatedly applied to a photoconductor having a non-uniform photosensitive layer having a microscopic composition, the photosensitive layer is likely to be distorted and easily cracked. Become. Specifically, in the image forming process, when pressure is repeatedly applied to the photoreceptor, the photosensitive layer may be distorted and the distortion may remain in the photosensitive layer. It is considered that when the photosensitive member is further subjected to pressure while distortion remains in the photosensitive layer, the photosensitive layer is easily cracked.
In particular, the occurrence of cracks in the photosensitive layer tends to occur easily in the photosensitive layer containing the specific electron transport material.
When cracks occur in the photosensitive layer, the charged charges leak (leak), and image point defects (for example, color points such as black spots increase) are likely to occur.
On the other hand, in the photoreceptor according to this embodiment, the elastic deformation rate R of the photosensitive layer containing the specific electron transport material is set to 0.340 or more and 0.360 or less. That is, the photosensitive layer is positively easily elastically deformed. As a result, even if pressure is repeatedly applied to the photosensitive member and distortion occurs in the photosensitive layer, the distortion is less likely to remain in the photosensitive layer. As a result, the occurrence of cracks in the photosensitive layer is suppressed even when pressure is repeatedly applied to the photoreceptor.
Further, in the photoconductor according to the present embodiment, the occurrence of cracks in the photosensitive layer is suppressed for the above-described reason, so that point defects in the image caused by the cracks are also suppressed.

In addition, when a toner image is directly transferred from an electrophotographic photosensitive member to a recording medium (for example, paper), the recording medium comes into contact with the surface of the photosensitive member, so that the recording medium component (calcium carbonate, silica, etc. ) Adheres to and adheres to the photoconductor (filming), and the surface resistance may be lowered to cause uneven image quality.
On the other hand, in the electrophotographic photoreceptor according to another embodiment, the Young's modulus E of the photosensitive layer containing the specific electron transport material is 4.40 GPa or more, and the elastic deformation rate R is 0.340 or more and 0.360 or less. And That is, the photosensitive layer is hard and positively easily elastically deformed. Thereby, embedding of the recording medium component in the photosensitive layer is suppressed, and as a result, filming is also suppressed.

Further, in this embodiment, when an electron transport material having an aromatic ring at the position of R ^{18 in} the general formula (I) is used as the specific electron transport material, the distortion generated in the photosensitive layer is more sensitive to the photosensitive layer. And the occurrence of cracks in the photosensitive layer is further suppressed. And it becomes easy to be suppressed also about filming. This is presumably because the structure of the substituent of R ^{18 in} the general formula (I) affects the compatibility with the binder resin. Specifically, when R ¹⁸ is a substituent having an aromatic ring (that is, an aryl group or an aralkyl group), compatibility with the binder resin is increased, and the elastic deformation rate R of the photosensitive layer is decreased. Is suppressed (that is, the photosensitive layer is easily elastically deformed).

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

  Hereinafter, each layer of the electrophotographic photoreceptor according to the exemplary embodiment will be described in detail. Note that the reference numerals are omitted.

(Conductive substrate)
Examples of the conductive substrate include metal plates (eg, aluminum, copper, zinc, chromium, nickel, molybdenum, vanadium, indium, gold, platinum, etc.) or alloys (stainless steel, etc.), metal drums, metal belts, etc. Is mentioned. In addition, as the conductive substrate, for example, paper, resin film, belt, etc. coated, vapor-deposited or laminated with a conductive compound (for example, conductive polymer, indium oxide, etc.), metal (for example, aluminum, palladium, gold, etc.) or an alloy, etc. Also mentioned. Here, “conductive” means that the volume resistivity is less than 10 ¹³ Ωcm.

  When the electrophotographic photosensitive member is used in a laser printer, the surface of the conductive substrate has a center line average roughness Ra of 0.04 μm or more and 0.5 μm for the purpose of suppressing interference fringes generated when laser light is irradiated. The surface is preferably roughened below. When non-interfering light is used as a light source, roughening for preventing interference fringes is not particularly required, but it is suitable for extending the life because it suppresses generation of defects due to irregularities on the surface of the conductive substrate.

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

  As a roughening method, without roughening the surface of the conductive substrate, conductive or semiconductive powder is dispersed in the resin to form a layer on the surface of the conductive substrate. The method of roughening by the particle | grains disperse | distributed in a layer is also mentioned.

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

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

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

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

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

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

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

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

  The inorganic particles may be subjected to a surface treatment. Two or more inorganic particles having different surface treatments or particles having different particle diameters may be mixed and used.

  Examples of the surface treatment agent include a silane coupling agent, a titanate coupling agent, an aluminum coupling agent, and a surfactant. In particular, a silane coupling agent is preferable, and an amino group-containing silane coupling agent is more preferable.

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

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

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

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

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

Examples of the electron accepting compound include quinone compounds such as chloranil and bromoanil; tetracyanoquinodimethane compounds; 2,4,7-trinitrofluorenone, 2,4,5,7-tetranitro-9-fluorenone, and the like. 2- (4-biphenyl) -5- (4-t-butylphenyl) -1,3,4-oxadiazole, 2,5-bis (4-naphthyl) -1,3,4- Oxadiazole compounds such as oxadiazole and 2,5-bis (4-diethylaminophenyl) -1,3,4 oxadiazole; xanthone compounds; thiophene compounds; 3,3 ′, 5,5 ′ tetra- electron transporting substances such as diphenoquinone compounds such as t-butyldiphenoquinone;
In particular, the electron-accepting compound is preferably a compound having an anthraquinone structure. As the compound having an anthraquinone structure, for example, a hydroxyanthraquinone compound, an aminoanthraquinone compound, an aminohydroxyanthraquinone compound, and the like are preferable, and specifically, for example, anthraquinone, alizarin, quinizarin, anthralfin, and purpurin are preferable.

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

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

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

  In the wet method, for example, an electron-accepting compound is added while dispersing inorganic particles in a solvent by stirring, ultrasonic waves, a sand mill, an attritor, a ball mill, etc., and after stirring or dispersing, the solvent is removed to remove electrons. This is a method of attaching a receptive compound to the surface of inorganic particles. The solvent removal method is distilled off by filtration or distillation, for example. After removing the solvent, baking may be performed at 100 ° C. or higher. The baking is not particularly limited as long as it is a temperature and time for obtaining electrophotographic characteristics. In the wet method, the water content of the inorganic particles may be removed before adding the electron-accepting compound. Examples thereof include a method of removing while stirring and heating in a solvent, and a method of removing by azeotropic distillation with a solvent. Can be mentioned.

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

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

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

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

The undercoat layer may contain various additives for improving electrical characteristics, improving environmental stability, and improving image quality.
Additives include known materials such as electron transport pigments such as polycyclic condensation systems and azo systems, zirconium chelate compounds, titanium chelate compounds, aluminum chelate compounds, titanium alkoxide compounds, organic titanium compounds, and silane coupling agents. It is done. The silane coupling agent is used for the surface treatment of the inorganic particles as described above, but may be further added to the undercoat layer as an additive.

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

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

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

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

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

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

  There is no particular limitation on the formation of the undercoat layer, and a well-known formation method is used. For example, a coating film for forming an undercoat layer in which the above components are added to a solvent is formed, and the coating film is dried. And heating as necessary.

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

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

  Examples of the method for applying the coating liquid for forming the undercoat layer onto the conductive substrate include, for example, 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. The usual methods, such as these, are mentioned.

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

(Middle layer)
Although illustration is omitted, an intermediate layer may be further provided between the undercoat layer and the photosensitive layer.
An intermediate | middle layer is a layer containing resin, for example. Examples of the resin used for the intermediate layer include an acetal resin (for example, polyvinyl butyral), polyvinyl alcohol resin, polyvinyl acetal resin, casein resin, polyamide resin, cellulose resin, gelatin, polyurethane resin, polyester resin, methacrylic resin, acrylic resin, Polymer compounds such as polyvinyl chloride resin, polyvinyl acetate resin, vinyl chloride-vinyl acetate-maleic anhydride resin, silicone resin, silicone-alkyd resin, phenol-formaldehyde resin, melamine resin, and the like can be given.
The intermediate layer may be a layer containing an organometallic compound. Examples of the organometallic compound used for the intermediate layer include organometallic compounds containing metal atoms such as zirconium, titanium, aluminum, manganese, and silicon.
The compounds used for these intermediate layers may be used alone or as a mixture or polycondensate of a plurality of compounds.

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

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

  For example, the thickness of the intermediate layer is preferably set in a range of 0.1 μm to 3 μm. An intermediate layer may be used as the undercoat layer.

(Single layer type photosensitive layer)
A single-layer type photosensitive layer (hereinafter sometimes simply referred to as “photosensitive layer”) includes a binder resin, a charge generating material, a hole transporting material, an electron transporting material, and other additives as necessary. An agent.

-Elastic deformation rate R-
The elastic deformation rate R of the photosensitive layer is 0.340 or more and 0.360 or less, preferably 0.345 or more and 0.360 or less, more preferably 0.350 or more and 0.360 or less.
Here, the elastic deformation rate R is defined as R = elastic deformation amount / total deformation amount by dividing the total deformation amount when a load is applied to the photosensitive layer into an elastic deformation amount and a plastic deformation amount. Specifically, the indentation depth and the indentation depth-stress curve are measured by using Nanoindenter SA2 manufactured by MTS, DCM head, and diamond regular triangular pyramid indenter. Specifically, as the measurement conditions, the indentation depth is set to Dmax (nm) when the indentation depth is set to 500 nm in an environment of a temperature of 24 ° C. and a humidity of 50%, and then completely unloaded. The indentation depth is D1 (nm), and the elastic deformation rate R is calculated using the following equation.
[Formula] Elastic deformation ratio R = (Dmax−D1) / Dmax

  By setting the elastic deformation rate R to 0.340 or more, the photosensitive layer is easily elastically deformed. As a result, even if pressure is repeatedly applied to the photosensitive member and distortion occurs in the photosensitive layer, the distortion is less likely to remain in the photosensitive layer. As a result, the occurrence of cracks in the photosensitive layer is suppressed. In addition, image point defects caused by cracks in the photosensitive layer are also suppressed. Further, by setting the elastic deformation rate R to 0.340 or more, the photosensitive layer is hardly plastically deformed. As a result, even if the recording medium component repeatedly contacts the photosensitive member, it is difficult to be embedded in the photosensitive layer and to remain in the photosensitive layer. As a result, filming on the surface of the photosensitive layer is suppressed. In addition, image unevenness caused by filming on the surface of the photosensitive layer is also suppressed. On the other hand, even if the elastic deformation rate R of the photosensitive layer is simply increased, it is difficult to obtain characteristics such as sensitivity for functioning as a photoreceptor. Therefore, by setting the upper limit of the elastic deformation rate R of the photosensitive layer to 0.360, the function as the photosensitive member is ensured.

  Examples of the method for controlling the elastic deformation rate R of the photosensitive layer within the above range include a method of changing the content of each component in the photosensitive layer. As a method for changing the content of each component in the photosensitive layer, specifically, for example, a method of increasing or decreasing the content of the binder resin relative to the photosensitive layer; a method of increasing or decreasing the content of the electron transport material relative to the binder resin; Is mentioned.

-Young's modulus E-
The Young's modulus E of the photosensitive layer is 4.40 GPa or more, preferably 4.46 GPa or more, more preferably 4.52 GPa or more. The upper limit of the Young's modulus E is not particularly limited, but is preferably 4.76 GPa or less from the viewpoint of setting the elastic deformation rate R in the above range.
By setting the Young's modulus E to 4.40 GPa or more, the hardness of the photosensitive layer itself is increased. In this embodiment, by setting the Young's modulus E and elastic deformation rate R in the above ranges, the photosensitive layer is hard and easily elastically deformed. As a result, filming of the recording medium component on the photosensitive layer is further suppressed. In addition, image unevenness caused by filming on the surface of the photosensitive layer is further suppressed.
The Young's modulus E is obtained from the displacement amount and stress when the indentation depth is 500 nm by using Nanodenter SA2, manufactured by MTS, a DCM head, and a diamond regular triangular pyramid indenter in the same manner as the elastic deformation rate R described above.

  Examples of the method for controlling the Young's modulus E of the photosensitive layer within the above range include a method of changing the content of each component in the photosensitive layer. Specific examples of the method of changing the content of each component in the photosensitive layer include a method of adjusting the content (for example, 60% by mass or less) of the binder resin.

-Binder resin-
The binder resin is not particularly limited. For example, polycarbonate resin, polyester resin, polyarylate resin, methacrylic resin, acrylic resin, polyvinyl chloride resin, polyvinylidene chloride resin, polystyrene resin, polyvinyl acetate resin, styrene-butadiene. Copolymer, vinylidene chloride-acrylonitrile copolymer, vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl acetate-maleic anhydride copolymer, silicone resin, silicone alkyd resin, phenol-formaldehyde resin, styrene-alkyd resin , Poly-N-vinylcarbazole, polysilane and the like. These binder resins may be used alone or in combination of two or more.
Among these binder resins, in particular, from the viewpoint of film formability of the photosensitive layer, for example, a polycarbonate resin having a viscosity average molecular weight of 30,000 to 80,000 is preferable.

The viscosity average molecular weight is measured by the following method. Specifically, 1 g of resin is dissolved in 100 cm ³ of methylene chloride, and its specific viscosity ηsp is measured with an Ubbelohde viscometer in a measurement environment at 25 ° C. Then, the intrinsic viscosity [η] (cm ³ / g) is determined from the relational expression of ηsp / c = [η] +0.45 [η] ² c (where c is the concentration (g / cm ³ )). The viscosity average molecular weight Mv is determined from the equation given by Schnell, [η] = 1.23 × 10 ⁻⁴ Mv 0.83, and the above one-point measurement method is used.

  The content of the binder resin with respect to the total solid content of the photosensitive layer is preferably 35% by mass to 60% by mass, preferably 50% by mass to 60% by mass, and more preferably 53% by mass. % To 60% by mass.

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

  Among these, in order to cope with near-infrared laser exposure, it is preferable to use a metal phthalocyanine pigment or a metal-free phthalocyanine pigment as the charge generation material. Specifically, for example, hydroxygallium phthalocyanine disclosed in JP-A-5-263007, JP-A-5-279591, etc .; chlorogallium phthalocyanine disclosed in JP-A-5-98181; More preferred are dichlorotin phthalocyanines disclosed in JP-A No. 140472, JP-A No. 5-140473 and the like; and titanyl phthalocyanine disclosed in JP-A No. 4-189873.

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

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

In this embodiment, it is preferable to use at least one selected from a hydroxygallium phthalocyanine pigment and a chlorogallium phthalocyanine pigment as the charge generation material.
As the charge generation material, these pigments may be used alone or in combination as required. The charge generating material is preferably a hydroxygallium phthalocyanine pigment from the viewpoint of increasing the sensitivity of the photoreceptor and suppressing point defects in the image.

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

The hydroxygallium phthalocyanine pigment having the maximum peak wavelength in the range of 810 nm or more and 839 nm or less preferably has an average particle diameter in a specific range and a BET specific surface area in a specific range. Specifically, the average particle size is preferably 0.20 μm or less, and more preferably 0.01 μm or more and 0.15 μm or less. On the other hand, the BET specific surface area is preferably 45 m ² / g or more, more preferably 50 m ² / g or more, and particularly preferably 55 m ² / g or more and 120 m ² / g or less. The average particle size is a 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).
Here, when the average particle diameter is larger than 0.20 μm, or when the specific surface area value is less than 45 m ² / g, the pigment particles may be coarsened or aggregates of the pigment particles may be formed. . In some cases, defects such as dispersibility, sensitivity, chargeability, and dark attenuation characteristics are likely to occur, which may cause image quality defects.

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

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

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

On the other hand, the chlorogallium phthalocyanine pigment is not particularly limited, but a Bragg angle (2θ ± 0.2 °) of 7.4 °, 16.6 °, 25.25 can be obtained as an electrophotographic photosensitive material. It is preferable to have diffraction peaks at 5 ° and 28.3 °.
The maximum peak wavelength, average particle diameter, maximum particle diameter, and specific surface area value of a suitable spectral absorption spectrum of the chlorogallium phthalocyanine pigment are the same as those of the hydroxygallium phthalocyanine pigment.

  The content of the charge generating material with respect to the total solid content of the photosensitive layer is preferably 1% by mass to 5% by mass, and preferably 1% by mass to 3% by mass.

-Hole transport material-
Examples of the hole transport material include compounds such as triarylamine compounds, benzidine compounds, arylalkane compounds, aryl-substituted ethylene compounds, stilbene compounds, anthracene compounds, and hydrazone compounds. These hole transport materials may be used alone or in combination of two or more, but are not limited thereto.

As the hole transport material, from the viewpoint of charge mobility, for example, a compound represented by the following general formula (1), a compound represented by the following general formula (B-1), and the following general formula (B-2) And compounds represented by the following general formula (B-3) are preferred. Further, as the hole transport material, a compound represented by the following general formula (1) is particularly preferable from the viewpoint of dispersibility in the photosensitive layer.
First, the compound represented by the following general formula (1) will be described.

In general formula (1), R ¹ , R ² , R ³ , R ⁴ , R ⁵ , and R ⁶ are each independently a hydrogen atom, a lower alkyl group, an alkoxy group, a phenoxy group, a halogen atom, or a lower group. A phenyl group optionally having a substituent selected from an alkyl group, a lower alkoxy group and a halogen atom is shown. m and n each independently represents 0 or 1.

In the general formula (1), examples of the lower alkyl group represented by R ^{1 to} R ⁶ include linear or branched alkyl groups having 1 to 4 carbon atoms. Specifically, for example, Examples thereof include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, and an isobutyl group.
Among these, the lower alkyl group is preferably a methyl group or an ethyl group.

In the general formula (1), examples of the alkoxy group represented by R ^{1 to} R ⁶ include an alkoxy group having 1 to 4 carbon atoms, and specifically include a methoxy group, an ethoxy group, a propoxy group, and a butoxy group. Etc.

In general formula (1), examples of the halogen atom represented by R ^{1 to} R ⁶ include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

In the general formula (1), examples of the phenyl group represented by R ^{1 to} R ⁶ include an unsubstituted phenyl group; a phenyl group substituted with a lower alkyl group such as a p-tolyl group or a 2,4-dimethylphenyl group; -A phenyl group substituted with a lower alkoxy group such as a methoxyphenyl group; a phenyl group substituted with a halogen atom such as a p-chlorophenyl group;
Examples of the substituent that can be substituted on the phenyl group include a lower alkyl group, an alkoxy group, and a halogen atom represented by R ^{1 to} R ⁶ .

The hole transport material represented by the general formula (1) is preferably a hole transport material in which m and n are 1 from the viewpoints of increasing sensitivity and suppressing point defect of an image, and in particular, R ^{1 to} R ^6. Each independently represents a hydrogen atom, a lower alkyl group, or an alkoxy group, and a hole transport material in which m and n are 1 is preferable.

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

In addition, the abbreviations in the above exemplary compounds have the following meanings.
4-Me: a methyl group substituted at the 4-position of the phenyl group, 3-Me: a methyl group substituted at the 3-position of the phenyl group, 4-Cl: a chlorine atom substituted at the 4-position of the phenyl group, 4 -MeO: methoxy group substituted at the 4-position of the phenyl group, 4-F: fluorine atom substituted at the 4-position of the phenyl group, 4-Pr: propyl group substituted at the 4-position of the phenyl group, 4-OPh : Phenoxy group substituted at 4-position of phenyl group

  Next, a compound (triarylamine derivative) represented by the following general formula (B-1), a compound (benzidine derivative) represented by the following general formula (B-2), and the following general formula (B-3) The compound represented by these is demonstrated.

In General Formula (B-1), R ^B1 represents a hydrogen atom or a methyl group. n11 represents 1 or 2. Ar ^B1 and Ar ^B2 are each independently a substituted or unsubstituted aryl group, —C ₆ H ₄ —C (R ^B3 ) ═C (R ^B4 ) (R ^B5 ), or —C ₆ H ₄ —CH═CH—. CH = C (R ^B6 ) (R ^B7 ), wherein R ^{B3 to} R ^B7 each independently represent a hydrogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aryl group. The substituent is a halogen atom, an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, or a substituted amino group substituted with an alkyl group having 1 to 3 carbon atoms.

(In General Formula (B-2), R ^B8 and R ^{B8 ′} 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 ^B9 , R ^{B9 ′} , R ^B10 and R ^{B10 ′} 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 ^B11 ) = C (R ^B12 ) (R ^B13 ), ^{or- CH = CH-CH = C (} R B14) indicates ^{(R B15),} representing the ^{R B11} to ^{R B15} are each independently a hydrogen atom, a substituted or unsubstituted alkyl group or a substituted or unsubstituted aryl group, .m 2, m13, n12 and n13 represents 2 the following integers each independently 0 or greater.

In general formula (B-3), R ^B16 and R ^{B16 ′} 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 an alkoxy having 1 to 5 carbon atoms. Group. R ^B17 , R ^{B17 ′} , R ^B18 , and R ^{B18 ′} may be the same or different and are each independently a halogen atom, an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, or a carbon number. An amino group substituted with 1 or more and 2 or less alkyl groups, a substituted or unsubstituted aryl group, —C (R ^B19 ) ═C (R ^B20 ) (R ^B21 ), or —CH═CH—CH═C (R ^B22 ) (R ^B23 ), and R ^{B19 to} R ^B23 each independently represent a hydrogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aryl group. m14, m15, n14 and n15 each independently represent an integer of 0 or more and 2 or less.

Here, among the compound represented by the general formula (B-1), the compound represented by the general formula (B-2), and the compound represented by the general formula (B-3), in particular, “—C ₆ H ₄ -CH = CH-CH = C (R ^B6 ) (R ^B7 ) "and the compound represented by the general formula (B-1) and" -CH = CH-CH = C (R ^B14 ) (R ^B15 ) " A compound represented by formula (B-2) is desirable.

  Specific examples of the compound represented by the general formula (B-1), the compound represented by the general formula (B-2), and the compound represented by the general formula (B-3) include the following compounds.

  The content of the hole transport material with respect to the total solid content of the photosensitive layer is preferably 10% by mass to 40% by mass, and preferably 30% by mass to 40% by mass.

-Electron transport material-
As the electron transport material, an electron transport material represented by the general formula (I) is applied.

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

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

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

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

In general formula (I), examples of the aryl group represented by R ^{11 to} R ¹⁷ include a phenyl group and a tolyl group.
In the general formula (I), examples of the aralkyl group represented by R ^{11 to} R ¹⁷ include a benzyl group.

Among the substituents represented by R ^{11 to} R ¹⁷ listed above, from the viewpoint of solubility in a solvent, R ¹¹ , R ¹² . R ¹³ . R ¹⁴ , R ¹⁵ , R ¹⁶ and R ¹⁷ are each independently preferably a hydrogen atom, a halogen atom or an alkyl group.

In the general formula (I), examples of the alkyl group represented by R ¹⁸ include a linear alkyl group having 1 to 15 carbon atoms (preferably 5 to 10 carbon atoms), and 3 to 15 carbon atoms ( A branched alkyl group having 5 to 10 carbon atoms is preferable.
Examples of the linear alkyl group having 1 to 15 carbon atoms include, for example, methyl group, ethyl group, n-propyl group, n-butyl group, n-pentyl group, n-hexyl group, n-heptyl group, n Examples include -octyl group, n-nonyl group, n-decyl group, n-undecyl group, n-dodecyl group, n-tridecyl group, n-tetradecyl group, n-pentadecyl group and the like.
Examples of the branched alkyl group having 3 to 15 carbon atoms include isopropyl group,
Isobutyl group, sec-butyl group, tert-butyl group, isopentyl group, neopentyl group, tert-pentyl group, isohexyl group, sec-hexyl group, tert-hexyl group, isoheptyl group, sec-heptyl group, tert-heptyl group, Isooctyl group, sec-octyl group, tert-octyl group, isononyl group, sec-nonyl group, tert-nonyl group, isodecyl group, sec-decyl group, tert-decyl group, isoundecyl group, sec-undecyl group, tert-undecyl group Group, isododecyl group, sec-dodecyl group, tert-dodecyl group, isotridecyl group, sec-tridecyl group, tert-tridecyl group, isotetradecyl group, sec-tetradecyl group, tert-tetradecyl group, isopentadecyl group, sec Pentadecyl group, tert- pentadecyl group and the like.

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

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

Specific examples of the aralkyl group represented by R ¹⁸ in the general formula (I) include benzyl group, methylbenzyl group, dimethylbenzyl group, phenylethyl group, methylphenylethyl group, ethylphenylethyl group, phenylpropyl group, and phenylbutyl. Groups and the like.

Among the substituents represented by R ¹⁸ listed above, an aryl group or an aralkyl group is preferable, and an aralkyl group is more preferable from the viewpoint of enhancing the compatibility with the binder resin and facilitating the reduction of the elastic deformation rate R. preferable.

  Hereinafter, although the exemplary compound of the electron transport material represented by general formula (I) is shown, it is not necessarily limited to this. In addition, the following exemplary compound numbers are described as an exemplary compound (I-number) below. Specifically, for example, Exemplified Compound 15 is represented below as “Exemplified Compound (I-15)”.

In addition, the abbreviations in the above exemplary compounds have the following meanings.
· -Ph: phenyl or phenylene group · _p-C 2 _{H 5:} substituted ethyl group in the para position

Here, the content of the electron transport material (specific electron transport material) represented by the general formula (I) with respect to the binder resin is 6 mass from the viewpoint of suppressing the decrease in Young's modulus E and elastic deformation rate R. % To 34% by mass, more preferably 8% to 34% by mass, and still more preferably 10% to 34% by mass.
When the content of the specific electron transport material with respect to the binder resin is 34% by mass or less, the photosensitive layer is easily elastically deformed. On the other hand, when the lower limit of the content of the specific electron transport material with respect to the binder resin is set to 20% by mass or more, the function (for example, sensitivity) as the photoreceptor is easily secured.
On the other hand, it is preferable that content of the specific electron transport material with respect to binder resin is 6 mass% or more and less than 20 mass%. By setting the content of the specific electron transport material with respect to the binder resin to 6% by mass or more and less than 20% by mass, the photosensitive layer is easily elastically deformed, and a decrease in Young's modulus is easily suppressed. Thereby, the occurrence of cracking of the photosensitive layer and the filming of the recording medium component on the photosensitive layer are easily suppressed.

  The content of the electron transport material with respect to the total solid content of the photosensitive layer is preferably 4% by mass or more and 22% by mass or less, and preferably 6% by mass or more and 16% by mass or less. In addition, content of this electron transport material is content of the whole electron transport material, when a specific electron transport material and another electron transport material are used together.

-Other electron transport materials-
Examples of other electron transport materials include quinone compounds such as p-benzoquinone, chloranil, bromanyl and anthraquinone, tetracyanoquinodimethane compounds, fluorenone compounds such as 2,4,7-trinitrofluorenone, and xanthone. And electron transporting compounds such as benzene-based compounds, benzophenone-based compounds, cyanovinyl-based compounds, and ethylene-based compounds. These other electron transport materials may be used alone or in combination of two or more, but are not limited thereto.

-Mass ratio of hole transport material and electron transport material-
The ratio of the hole transport material to the electron transport material is preferably 1 or more and 12 or less, more preferably 1.5 or more and 10 or less in terms of mass ratio (hole transport material / electron transport material).
This ratio is the total ratio when other electron transport materials are used in combination.

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

-Formation of single-layer type photosensitive layer-
The single-layer type photosensitive layer is formed using a photosensitive layer forming coating solution in which the above components are added to a solvent.
Solvents include aromatic hydrocarbons such as benzene, toluene, xylene and chlorobenzene, ketones such as acetone and 2-butanone, halogenated aliphatic hydrocarbons such as methylene chloride, chloroform and ethylene chloride, tetrahydrofuran and ethyl ether. And usual organic solvents such as cyclic or straight chain ethers. These solvents are used alone or in combination of two or more.

  As a method for dispersing particles (for example, charge generation material) in the coating solution for forming a photosensitive layer, a media disperser such as a ball mill, a vibrating ball mill, an attritor, a sand mill, a horizontal sand mill, an agitator, an ultrasonic disperser, a roll mill, Medialess dispersers such as high-pressure homogenizers are used. Examples of the high-pressure homogenizer include a collision method in which the dispersion liquid is dispersed by liquid-liquid collision or liquid-wall collision in a high-pressure state, and a penetration method in which a fine flow path is dispersed in a high-pressure state.

  Examples of the method for applying the photosensitive layer forming coating solution onto the undercoat layer include dip coating, push-up coating, wire bar coating, spray coating, blade coating, knife coating, and curtain coating. .

  The film thickness of the single-layer type photosensitive layer is preferably set in the range of 5 μm to 60 μm, more preferably 10 μm to 50 μm.

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

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

The reactive group of the reactive group-containing charge transport material includes a chain polymerizable group, an epoxy group, —OH, —OR [wherein R represents an alkyl group], —NH ₂ , —SH, —COOH, —SiR. ^Q1 _3-Qn (OR ^Q2 ) _Qn [wherein R ^Q1 represents a hydrogen atom, an alkyl group, or a substituted or unsubstituted aryl group, and R ^Q2 represents a hydrogen atom, an alkyl group, or a trialkylsilyl group. Qn represents an integer of 1 to 3], and the like, and other well-known reactive groups.

  The chain polymerizable group is not particularly limited as long as it is a functional group capable of radical polymerization. For example, it is a functional group having a group containing at least a carbon double bond. Specific examples include a group containing at least one selected from a vinyl group, a vinyl ether group, a vinyl thioether group, a vinylphenyl group (styryl group), an acryloyl group, a methacryloyl group, and derivatives thereof. Among them, since it has excellent reactivity, the chain polymerizable group includes a group containing at least one selected from a vinyl group, a vinylphenyl group (styryl group), an acryloyl group, a methacryloyl group, and derivatives thereof. It is preferable that

  The charge transporting skeleton of the reactive group-containing charge transporting material is not particularly limited as long as it is a known structure in an electrophotographic photoreceptor, and examples thereof include triarylamine compounds, benzidine compounds, hydrazone compounds, and the like. And a structure conjugated from a nitrogen-containing hole transporting compound and conjugated with a nitrogen atom. Among these, a triarylamine skeleton is preferable.

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

  In addition, the protective layer may contain known additives.

  The formation of the protective layer is not particularly limited, and a known formation method is used.For example, a coating film of a coating liquid for forming a protective layer in which the above components are added to a solvent is formed, and the coating film is dried. It is performed by performing a curing process such as heating as necessary.

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

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

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

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

  The image forming apparatus according to the present embodiment includes an apparatus having fixing means for fixing a toner image transferred to the surface of a recording medium; direct transfer for directly transferring the toner image formed on the surface of the electrophotographic photosensitive member to the recording medium Type apparatus; intermediate transfer in which the toner image formed on the surface of the electrophotographic photosensitive member is primarily transferred onto the surface of the intermediate transfer member, and the toner image transferred onto the surface of the intermediate transfer member is secondarily transferred onto the surface of the recording medium. Type apparatus; apparatus provided with cleaning means for cleaning the surface of the electrophotographic photosensitive member after the toner image is transferred and before charging; after the toner image is transferred, the surface of the image carrier is irradiated with a charge-removing light before charging. A known image forming apparatus, such as an apparatus provided with a static elimination means for removing electricity; an apparatus provided with an electrophotographic photosensitive member heating member for increasing the temperature of the electrophotographic photosensitive member and reducing the relative temperature is applied.

  In the case of an intermediate transfer type apparatus, the transfer means includes, for example, an intermediate transfer body on which a toner image is transferred onto the surface, and a primary transfer that primarily transfers the toner image formed on the surface of the image holding body onto the surface of the intermediate transfer body. And a secondary transfer unit that secondarily transfers the toner image transferred onto the surface of the intermediate transfer member onto the surface of the recording medium.

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

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

  Hereinafter, an example of the image forming apparatus according to the present embodiment will be described, but the present invention is not limited thereto. In addition, the main part shown to a figure is demonstrated and the description is abbreviate | omitted about others.

FIG. 2 is a schematic configuration diagram illustrating an example of an image forming apparatus according to the present embodiment.
As shown in FIG. 2, the image forming apparatus 100 according to the present embodiment includes a process cartridge 300 including an electrophotographic photosensitive member 7, an exposure device 9 (an example of an electrostatic latent image forming unit), and a transfer device 40 (primary. Transfer device) and an intermediate transfer member 50. In the image forming apparatus 100, the exposure device 9 is disposed at a position where the electrophotographic photosensitive member 7 can be exposed 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. Although not shown, it also has a secondary transfer device that transfers the toner image transferred to the intermediate transfer member 50 to a recording medium (for example, paper). The intermediate transfer member 50, the transfer device 40 (primary transfer device), and the secondary transfer device (not shown) correspond to an example of a transfer unit.
Note that the image forming apparatus 100 illustrated in FIG. 4 may be a direct transfer type image forming apparatus. In this case, the direct transfer type image forming apparatus includes, for example, a process cartridge 300 including the electrophotographic photosensitive member 7, an exposure device 9 (an example of an electrostatic latent image forming unit), a transfer device 40, and an intermediate transfer member 50. Instead of the recording medium conveying belt. Specifically, the transfer device 40 is disposed at a position facing the electrophotographic photosensitive member 7 through the recording medium conveyance belt, and a part of the recording medium conveyance belt is disposed in contact with the electrophotographic photosensitive member 7. Then, the recording medium (for example, paper) is conveyed by the recording medium conveyance belt to a position where the transfer device 40 and the electrophotographic photosensitive member 7 face each other, and the toner image transferred to the electrophotographic photosensitive member 7 by the transfer device 40 is recorded on the recording medium. Is transferred to. The material of the recording medium conveyance belt can be the same as or different from the material of the intermediate transfer member 50 described later.

  A process cartridge 300 in FIG. 2 includes an electrophotographic photosensitive member 7, a charging device 8 (an example of a charging unit), a developing device 11 (an example of a developing unit), and a cleaning device 13 (an example of a cleaning unit) in a housing. I support it. The cleaning device 13 includes a cleaning blade (an example of a cleaning member) 131, and the cleaning blade 131 is disposed so as to contact the surface of the electrophotographic photosensitive member 7. The cleaning member may be a conductive or insulating fibrous member instead of the cleaning blade 131, and may be used alone or in combination with the cleaning blade 131.

  In FIG. 2, as an image forming apparatus, a fibrous member 132 (roll shape) for supplying the lubricant 14 to the surface of the electrophotographic photosensitive member 7 and a fibrous member 133 (flat brush shape) for assisting in cleaning are shown. Examples are provided, but these are arranged as necessary.

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

-Charging device-
As the charging device 8, for example, a contact type charger using a conductive or semiconductive charging roller, a charging brush, a charging film, a charging rubber blade, a charging tube or the like is used. 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.

-Exposure device-
Examples of the exposure device 9 include optical system devices that expose the surface of the electrophotographic photoreceptor 7 with light such as semiconductor laser light, LED light, and liquid crystal shutter light in a predetermined image-like manner. The wavelength of the light source is set within the spectral sensitivity region of the electrophotographic photosensitive member. 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 an oscillation wavelength laser in the 600 nm range 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 color image formation.

-Developer-
Examples of the developing device 11 include a general developing device that performs development by bringing a developer into contact or non-contact with the developer. The developing device 11 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 attaching a one-component developer or a two-component developer to the electrophotographic photosensitive member 7 using a brush, a roller, or the like can be used. Among these, those using a developing roller holding the developer on the surface are preferable.

  The developer used in the developing device 11 may be a one-component developer including a toner alone or a two-component developer including a toner and a carrier. Further, the developer may be magnetic or non-magnetic. A well-known thing is applied for these developers.

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

-Transfer device-
As the transfer device 40, for example, a 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.

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

FIG. 3 is a schematic configuration diagram illustrating another example of the image forming apparatus according to the present embodiment.
An image forming apparatus 120 shown in FIG. 3 is a tandem 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 that of the image forming apparatus 100 except that it is a tandem system.

  Note that the image forming apparatus 100 according to the present embodiment is not limited to the above configuration, and is, for example, a cleaning device around the electrophotographic photosensitive member 7 and downstream of the transfer device 40 in the rotation direction of the electrophotographic photosensitive member 7. The first toner neutralizing device may be provided on the upstream side of the rotation direction of the electrophotographic photosensitive member with respect to 13 so that the polarity of the remaining toner is aligned and easily removed with a cleaning brush. Alternatively, a configuration in which a second static elimination device for neutralizing the surface of the electrophotographic photosensitive member 7 is provided on the downstream side in the rotation direction of the electrophotographic photosensitive member and on the upstream side in the rotational direction of the electrophotographic photosensitive member with respect to the charging device 8. .

  EXAMPLES Hereinafter, although this invention is demonstrated more concretely based on an Example and a comparative example, this invention is not limited to a following example at all. Unless otherwise specified, “parts” in the following Examples and Comparative Examples means “parts by mass” and “%” means “% by mass”.

<Example 1-1>
(Preparation of electrophotographic photoreceptor 1-1)
-Formation of photosensitive layer-
The Bragg angle (2θ ± 0.2 °) of an X-ray diffraction spectrum using Cukα characteristic X-ray as a charge generation material (indicated as “CGM” in Table 1) is at least 7.3 °, 16.0 °, 24. 1.5 parts by mass of a V-type hydroxygallium phthalocyanine pigment having diffraction peaks at 9 ° and 28.0 °, and 58.5 parts by mass of a bisphenol Z polycarbonate resin (viscosity average molecular weight: 50,000) as a binder resin 10 parts by mass of an electron transport material shown in Table 1 (indicated as “ETM” in Table 1), 30 parts by mass of a hole transport material as shown in Table 1 (indicated as “HTM” in Table 1), and tetrahydrofuran 250 as a solvent. A mixture consisting of parts by mass was dispersed for 4 hours with a sand mill using glass beads having a diameter of 1 mmφ to obtain a coating solution for forming a photosensitive layer.

The obtained photosensitive layer forming coating solution was applied on an aluminum substrate having a diameter of 30 mm and a length of 244.5 mm by a dip coating method, followed by drying and curing at 140 ° C. for 30 minutes, and a single layer having a thickness of 28 μm. A layer-type photosensitive layer was formed.
Through the above steps, an electrophotographic photosensitive member 1-1 was produced. With respect to the obtained electrophotographic photoreceptor 1-1, the elastic deformation rate R of the photosensitive layer was calculated by the method described above.

<Examples 1-2 to 1-8, Comparative Examples 1-1 to 1-4>
(Preparation of electrophotographic photoreceptors 1-2 to 1-12)
According to Table 1, except that the type and amount of the charge generation material (CGM), the hole transport material (HTM), the electron transport material (ETM), and the binder resin were changed, the same as the electrophotographic photoreceptor 1, Electrophotographic photoreceptors 1-2 to 1-12 were prepared. For the obtained electrophotographic photoreceptors 1-2 to 1-12, the elastic deformation rate R of the photosensitive layer was calculated by the method described above. The results are shown in Table 1.

<Evaluation>
Using the electrophotographic photoreceptors 1-1 to 1-12 (hereinafter, simply referred to as “photoreceptors 1-1 to 1-12”) obtained in each example, the following evaluations were performed. The results are shown in Table 2.

[Evaluation of sensitivity]
The photoreceptors 1-1 to 1-12 of each example were mounted on an electrostatic copying paper test apparatus (electrostatic analyzer EPA-8100, manufactured by Kawaguchi Electric Mfg. Co., Ltd.), and the sensitivity was evaluated.
The sensitivity was evaluated as a half-exposure amount when charged to + 800V. Specifically, after charging to + 800V in an environment of 20 ° C. and 40% RH using the electrostatic copying paper test apparatus, the light of the tungsten lamp is changed to a monochromatic light of 800 nm using a monochromator, Irradiation was carried out by adjusting to 1 μW / cm ² on the surface of the photoreceptor.
Then, the surface potential V0 (V) on the surface of the photoreceptor immediately after charging is set, and the half exposure amount E1 / 2 (μJ / cm ² ) at which the surface potential becomes 1/2 × VO (V) by light irradiation on the surface of the photoreceptor. It was measured. The evaluation criteria are as follows.

-Evaluation criteria-
A: Half exposure amount is 0.10 μJ / cm ² or more and 0.15 μJ / cm ² or less B: Half exposure amount is more than 0.15 μJ / cm ² and 0.20 μJ / cm ² or less C: Half exposure amount is 0.20 μJ / Cm ²

[Image quality evaluation 1]
The photoreceptors 1-1 to 1-12 of each example were mounted on a modified machine (HL5340D manufactured by Brother), and the following image quality evaluation 1 was performed.
In the image quality evaluation 1, 20000 halftone images having an image density of 10% were output at 10 sheets / min and 4000 sheets / day using the modified machine in an environment of a room temperature of 32 ° C. and a humidity of 80%.
Thereafter, the operation was stopped overnight, and the presence or absence of color spots (for example, black spots) per circumference of the photoreceptor in the first blank image of the next morning was evaluated according to the following criteria.

-Evaluation criteria-
A: No generation of color points due to cracks in the photosensitive layer B: Color points due to cracks in the photosensitive layer can be confirmed in the range of 1 to 9, but there is no problem in practical use. Ten or more color points due to cracks have been confirmed, causing problems in actual use

From the above results, it was found that, in image quality evaluation 1, in this example, the generation of color points due to cracking of the photosensitive layer was suppressed.
In particular, Examples 1-1 to 1-8 having a photosensitive layer having an elastic strain rate R of 0.340 or more and 0.360 or less are Comparative Examples 1-1 having a photosensitive layer having an elastic strain rate R of less than 0.340. It was found that the generation of color points due to cracking of the photosensitive layer was suppressed as compared with 1-2, 1-4.
Examples 1-2 to 1-8 using an electron transport material in which R ¹⁸ in the general formula (1) is an aralkyl group are examples 1 using an electron transport material in which R ¹⁸ is an alkyl group. It was found that the sensitivity of the photosensitive layer tends to be better than that of -1, and the generation of color points due to cracking of the photosensitive layer tends to be further suppressed.
Further, Examples 1-3 to 1-8 in which the content of the electron transport material with respect to the binder resin is 20% by mass or more and 34% by mass or less are Example 1 in which the content of the electron transport material is less than 20% by mass. It was found that the generation of color points due to cracking of the photosensitive layer was further suppressed as compared with 1, 1-2.
In Comparative Example 1-3 in which the elastic strain rate R of the photosensitive layer exceeded 0.360, the evaluation of sensitivity was C, although the generation of color points due to cracking of the photosensitive layer was suppressed.
Furthermore, it was found that the photoconductor of this example has good sensitivity and also has a function as a photoconductor.

<Example 2-1>
(Preparation of electrophotographic photoreceptor 2-1)
-Formation of photosensitive layer-
The Bragg angle (2θ ± 0.2 °) of an X-ray diffraction spectrum using Cukα characteristic X-ray as a charge generation material (indicated as “CGM” in Table 1) is at least 7.3 °, 16.0 °, 24. 1.5 parts by mass of a V-type hydroxygallium phthalocyanine pigment having diffraction peaks at 9 ° and 28.0 °, and 51.5 parts by mass of a bisphenol Z polycarbonate resin (viscosity average molecular weight: 50,000) as a binder resin 12 parts by mass of an electron transport material shown in Table 1 (indicated as “ETM” in Table 1), 35 parts by mass of a hole transport material as shown in Table 1 (indicated as “HTM” in Table 1), and tetrahydrofuran 250 as a solvent. A mixture consisting of parts by mass was dispersed for 4 hours with a sand mill using glass beads having a diameter of 1 mmφ to obtain a coating solution for forming a photosensitive layer.

The obtained photosensitive layer forming coating solution is applied on an aluminum substrate having a diameter of 30 mm and a length of 244.5 mm by a dip coating method, followed by drying and curing at 140 ° C. for 30 minutes, and a single layer having a thickness of 25 μm. A layer-type photosensitive layer was formed.
Through the above steps, an electrophotographic photoreceptor 2-1 was produced. With respect to the obtained electrophotographic photosensitive member 2-1, the elastic deformation rate R and Young's modulus E of the photosensitive layer were calculated by the method described above. The results are shown in Table 3.

<Examples 2-2 to 2-9, Comparative Examples 2-1 to 2-2>
(Preparation of electrophotographic photoreceptors 2-2 to 2-11)
According to Table 1, except that the kind and amount of the charge generation material (CGM), the hole transport material (HTM), the electron transport material (ETM), and the binder resin were changed, the same as the electrophotographic photoreceptor 2-1. Electrophotographic photoreceptors 2-2 to 2-11 were prepared. For the obtained electrophotographic photoreceptors 2-2 to 2-11, the elastic deformation rate R and Young's modulus E of the photosensitive layer were calculated by the above-described methods. The results are shown in Table 3.

<Evaluation>
Using the electrophotographic photosensitive members 2-1 to 2-11 (hereinafter simply referred to as “photosensitive members 2-1 to 2-11”) obtained in the respective examples, the following image quality evaluation was performed. The results are shown in Table 4.

[Image quality evaluation 1]
The photoreceptors 2-1 to 2-11 in each example were mounted on a direct transfer type remodeling machine (Brother HL5340D), and the following image quality evaluation 1 was performed.
In the image quality evaluation 1, 20000 halftone images having an image density of 10% were output at 10 sheets / min and 4000 sheets / day using the modified machine in an environment of a room temperature of 32 ° C. and a humidity of 80%.
Thereafter, the operation was stopped overnight, and the presence or absence of color spots (for example, black spots) per circumference of the photoreceptor in the first blank image of the next morning was evaluated according to the following criteria.

-Evaluation criteria-
A: No generation of color points due to cracks in the photosensitive layer B: Color points due to cracks in the photosensitive layer can be confirmed in the range of 1 to 9, but there is no problem in practical use. Ten or more color points due to cracks have been confirmed, causing problems in actual use

[Image quality evaluation 2]
The obtained photoreceptors 2-1 to 2-11 were subjected to the following image quality evaluation 2.
Mounted on a Brother HL-L2360DN remodeling machine under an environment of temperature 10 ° C. and humidity 15% RH, an image with an image density of 1% at 10 sheets / minute and 3000 sheets / day is recorded by Xerox 6000 sheets were output on medium (paper) X4200. Immediately after outputting 6000 sheets, one halftone image having an image density of 30% was output.
Density unevenness caused by sheet component filming in a halftone image was determined according to the following criteria. Further, when the basic electrical characteristics were insufficient and the halftone density was not obtained, the evaluation standard D was determined.

-Evaluation criteria-
A: B concentration unevenness does not occur: very Yes slight density unevenness B ^-: between B and C, and Nashi actual use problems C: There are uneven density, D practical use of problems: Halftone There is a problem in practical use at low concentration

From the above results, it was found that, in image quality evaluation 1, in this example, the generation of color points due to cracking of the photosensitive layer was suppressed.
In the image quality evaluation 2, in Examples 2-1 to 2-9 in which the elastic strain rate R of the photosensitive layer is 0.340 or more and 0.360 or less, the Young's modulus E of the photosensitive layer is 4.40 GPa or more. In Examples 2-1 to 2-8, compared to Example 2-9 in which the Young's modulus E is less than 4.40 GPa, the generation of color points due to cracking of the photosensitive layer is suppressed, and the paper component film is filled. It was found that density unevenness caused by the ming was also suppressed.
Examples 2-2 to 2-8 using an electron transport material in which R ¹⁸ in the general formula (1) is an aralkyl group are examples 2 using an electron transport material in which R ¹⁸ is an alkyl group. As compared with -1 and 2-9, it has been found that the occurrence of color points due to cracking of the photosensitive layer tends to be good, and density unevenness due to filming of the paper component tends to be further suppressed. .
In Comparative Example 2-2 in which the elastic strain rate R of the photosensitive layer exceeds 0.360, the generation of color points due to cracking of the photosensitive layer is suppressed, but density unevenness due to filming of the paper component is suppressed. Evaluation was D.
From the above results, it is attributed to cracking of the photosensitive layer by mounting the photosensitive member having the elastic strain rate R and Young's modulus E of the photosensitive layer in specific ranges and forming an image with a direct transfer type image forming apparatus. It was found that the generation of color points is suppressed and density unevenness due to the filming of the paper components is also suppressed.

The details of the abbreviations in Tables 1 and 3 are shown below.
-Charge generation material-
HOGaPC: Diffraction at a Bragg angle (2θ ± 0.2 °) of X-ray diffraction spectrum using Cukα characteristic X-ray of at least 7.3 °, 16.0 °, 24.9 °, 28.0 ° V-type hydroxygallium phthalocyanine pigment having a peak (maximum peak wavelength in spectral absorption spectrum in wavelength range of 600 nm to 900 nm = 820 nm, average particle diameter = 0.12 μm, maximum particle diameter = 0.2 μm, specific surface area value = 60m ² / g)

・ ClGaPC: Diffraction to the position where the Bragg angle (2θ ± 0.2 °) of X-ray diffraction spectrum using Cukα characteristic X-ray is at least 7.4 °, 16.6 °, 25.5 °, 28.3 ° Chlorogallium phthalocyanine pigment having a peak (maximum peak wavelength in spectral absorption spectrum in wavelength range of 600 nm to 900 nm = 780 nm, average particle size = 0.15 μm, maximum particle size = 0.2 μm, specific surface area value = 56 m ² / g)

-Hole transport material-
HT-1: A hole transport material having the following structure (an exemplary compound (HT-1) of a hole transport material (benzidine derivative) represented by the general formula (B-2)). However, Me shows a methyl group.
HT-A: hole transport material having the following structure (an example compound (1-1) of a hole transport material represented by the general formula (1))

-Electron transport material-
ET-A: an electron transport material having the following structure (an exemplary compound (I-2) of an electron transport material represented by the general formula (I))
ET-B: an electron transport material having the following structure (an exemplary compound (I-15) of an electron transport material represented by the general formula (I))
ET-C: an electron transport material having the following structure (an exemplary compound (I-17) of an electron transport material represented by the general formula (I))
ET-D: an electron transport material having the following structure (an exemplary compound (I-1) of an electron transport material represented by the general formula (I))

-Binder resin-
PCZ: Bisphenol Z polycarbonate resin (viscosity average molecular weight: 50,000)

DESCRIPTION OF SYMBOLS 1 Undercoat layer, 2 Photosensitive layer, 3 Conductive substrate, 7 Electrophotographic photoreceptor, 8 Charging device, 9 Exposure device, 10 Electrophotographic photoreceptor, 11 Developing device, 13 Cleaning device, 14 Lubricant, 40 Transfer device, 50 intermediate transfer member, 100 image forming apparatus, 120 image forming apparatus, 131 cleaning blade, 132 fibrous member, 133 fibrous member, 300 process cartridge

Claims (7)

A conductive substrate;
A single-layer type photosensitive layer provided on the conductive substrate, comprising a binder resin, a charge generation material, a hole transport material, an electron transport material represented by the following general formula (I), A photosensitive layer having an elastic deformation rate R of 0.340 or more and 0.360 or less,
An electrophotographic photosensitive member having:

(In the general formula (I), R ¹¹ , R ¹² , R ¹³ , R ¹⁴ , R ¹⁵ , R ¹⁶ , and R ¹⁷ are each independently a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group, an aryl group, Or R ¹⁸ represents an alkyl group, an aryl group, or an aralkyl group.   The electrophotographic photosensitive member according to claim 1, wherein the photosensitive layer is provided as an outermost surface layer, and the Young's modulus E of the photosensitive layer is 4.40 GPa or more. The electrophotographic photosensitive member according to claim 1, wherein R ¹⁸ in the general formula (1) is an aryl group or an aralkyl group.   4. The electrophotographic photosensitive member according to claim 1, wherein a content of the electron transport material with respect to the binder resin is 6% by mass or more and 34% by mass or less. The electrophotographic photosensitive member according to any one of claims 1 to 4, comprising:
A process cartridge that can be attached to and detached from an image forming apparatus. The electrophotographic photosensitive member according to any one of claims 1 to 4,
Charging means for charging the surface of the electrophotographic photosensitive member;
An electrostatic latent image forming means for forming an electrostatic latent image on the surface of the charged electrophotographic photosensitive member;
Developing means for developing the electrostatic latent image formed on the surface of the electrophotographic photosensitive member with a developer containing toner to form a toner image;
Transfer means for transferring the toner image to the surface of the recording medium;
An image forming apparatus comprising:   The image forming apparatus according to claim 6, wherein the transfer unit is a transfer unit that directly transfers the toner image onto the surface of the recording medium.