JP6229513B2 - Image forming apparatus and process cartridge - Google Patents

Description

  The present invention relates to an image forming apparatus and a process cartridge.

  Patent Document 1, Patent Document 2, and Patent Document 3 disclose a diphenoquinone compound, a naphthalene carboxylic acid imide compound, and a naphthalene tetracarboxylic acid imide compound having specific structures, respectively.

  Patent Document 4 discloses an electrophotographic photosensitive member in which at least a photosensitive layer is provided on a conductive substrate, wherein the photosensitive layer contains a fluorene compound having a specific structure. ing

  Patent Document 5 discloses a photoconductive imaging member including a support base and a single layer on the support base, wherein the single layer includes a mixture of a photogenerating component, a charge transport component, an electron transport component, and a binder. A photoconductive imaging member is disclosed in which the electron transport component contains a 2-ethylhexanol derivative of (4-carbonyl-9-fluorenylidene) malononitrile having a specific structure.

  Patent Document 6 discloses an electrophotography having a single-layer type photosensitive layer containing at least a resin binder, a charge generation material, a hole transport material, and an electron transport material on a conductive substrate directly or via an undercoat layer. An electrophotographic photosensitive member is disclosed, wherein the photosensitive layer contains a biphenyl derivative in the photosensitive layer.

  Patent Document 7 discloses a positively charged single-layer type electron, wherein a photosensitive layer is formed on a conductive substrate, and the photosensitive layer contains a phthalocyanine compound as a charge generating agent and a terphenyl compound as an electron transporting agent. A photographic photoreceptor 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

  An object of the present invention is to provide an image forming apparatus in which a desired image density can be easily obtained, and an unintended black spot is hardly generated even in repeated use.

  The above problem is solved by the following means.

The invention according to claim 1
At least one charge selected from a binder resin, a hydroxygallium phthalocyanine pigment, and a chlorogallium phthalocyanine pigment, comprising: a conductive substrate; and a single layer type photosensitive layer provided on the conductive substrate. An electrophotographic photoreceptor comprising a generating material, a hole transport material, an electron transport material represented by the following general formula (1), and a phenolic antioxidant;
Charging means for charging such that the surface potential of the electrophotographic photosensitive member is 800 V or more and 1200 V or less;
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.

(In the general formula (1), 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 image forming apparatus according to claim 1, wherein the phenolic antioxidant includes an antioxidant represented by the following formula (2).

The invention according to claim 3
The image forming apparatus according to claim 1, wherein the phenolic antioxidant includes an antioxidant represented by the following formula (3).

The invention according to claim 4
The image forming apparatus according to claim 1, wherein the hole transport material is a hole transport material represented by the following general formula (4).

(In General Formula (4), 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 phenyl group which may have a substituent selected from a lower alkyl group, a lower alkoxy group and a halogen atom, and m and n each independently represent 0 or 1.

The invention according to claim 5
5. The image forming apparatus according to claim 1, wherein the phenolic antioxidant is contained in an amount of 5 parts by mass or more and 50 parts by mass or less with respect to 100 parts by mass of the electron transport material.
The invention according to claim 6
At least one charge selected from a binder resin, a hydroxygallium phthalocyanine pigment, and a chlorogallium phthalocyanine pigment, comprising: a conductive substrate; and a single layer type photosensitive layer provided on the conductive substrate. An electrophotographic photoreceptor comprising a generating material, a hole transport material, an electron transport material represented by the following general formula (1), and a phenolic antioxidant;
Charging means for charging such that the surface potential of the electrophotographic photosensitive member is 800 V or more and 1200 V or less;
And a process cartridge which is detachable from the image forming apparatus.

(In the general formula (1), 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.

  According to the invention of claim 1, the charging means is means for charging the surface of the electrophotographic photosensitive member to 800 V or more and 1200 V or less, and compared with the case where a phosphite antioxidant is used as the antioxidant, Provided is an image forming apparatus in which an intended image density can be easily obtained and an unintended black spot is unlikely to occur in an image even when it is repeatedly used.

  According to the invention which concerns on Claim 2 or Claim 3, compared with the case where the exemplary compound (P-1) of the following phenolic antioxidant is used as antioxidant, the target image density is easy to be obtained, and Thus, an image forming apparatus is provided in which unintended black spots are unlikely to occur even in repeated use.

  According to the invention of claim 4, compared to the case where the following triarylamine derivative is used as the hole transport material, the intended image density can be easily obtained, and black spots that are not intended for the image even after repeated use are obtained. An image forming apparatus that is unlikely to occur is provided.

According to the invention of claim 6 , the charging means is means for charging the surface of the electrophotographic photosensitive member to 800 V or more and 1200 V or less, and a phosphite antioxidant as an antioxidant in the single-layer type photosensitive layer. As compared with the case of using the process cartridge, a process cartridge in which a target image density can be easily obtained and an unintended black spot is hardly generated even in repeated use is provided.

1 is a schematic configuration diagram illustrating an image forming apparatus according to an exemplary embodiment. 1 is a schematic partial cross-sectional view showing an electrophotographic photosensitive member according to the present embodiment. It is a schematic block diagram which shows the image forming apparatus which concerns on other this embodiment.

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

<Image forming apparatus>
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. .

The electrophotographic photoreceptor provided in the image forming apparatus of the present embodiment is a positively charged organic photoreceptor (hereinafter referred to as “single layer type photosensitive member”) having a conductive substrate and a single layer type photosensitive layer on the conductive substrate. May be referred to as "body").
The single-layer type photosensitive layer is represented by a general formula (1), a binder resin, at least one charge generation material selected from a hydroxygallium phthalocyanine pigment and a chlorogallium phthalocyanine pigment, a hole transport material. An electron transport material, and a phenolic antioxidant.
The single-layer type photosensitive layer is a photosensitive layer having hole transporting properties and electron transporting properties as well as charge generation ability.

  The charging means provided in the image forming apparatus of this embodiment is a charging means for charging the surface of the electrophotographic photosensitive member to 800 V or more and 1200 V or less. That is, the surface potential (charging potential) of the electrophotographic photosensitive member charged by the charging unit is 800 V or more and 1200 V or less.

Here, conventionally, as the electrophotographic photoreceptor, a single-layer photoreceptor is desirable from the viewpoint of manufacturing cost and image quality stability.
On the other hand, the single-layer type photoreceptor has a configuration in which a charge generation material, a hole transport material, and an electron transport material are contained in the single-layer type photosensitive layer. For this reason, it is difficult to control the transport of charges in a single-layer type photoconductor in which the photosensitive layer is not functionally separated compared to an organic photoconductor (laminated photoconductor) having a functionally separated type photosensitive layer.

  As a method for making it easy to obtain the desired image density, there is a method in which a high potential is applied to the surface of the electrophotographic photosensitive member to form an image, thereby improving the gradation of the image and improving the output reproducibility. It is done. However, when an image is formed by applying a high potential to the single-layer type photoreceptor, unintentional black spots are likely to occur in the image after the image formation is repeated, as compared with the case of using a multilayer photoreceptor.

On the other hand, in this embodiment, the specific charge generation material, the specific electron transport material, and the phenolic antioxidant are combined and contained in a single-layer type photosensitive layer, and the surface potential of the single-layer type photoconductor is included. Is used in combination with a charging means for charging so as to be in the above range.
Therefore, compared to the case where the surface potential of the photosensitive member charged by the charging means is lower than the above range, a desired image density can be easily obtained, and the material to be contained in the photosensitive layer is other than the combination (for example, phenol) Compared to the case where an antioxidant other than the antioxidant is used, the case where an antioxidant is not used, or the case where an electron transport material other than the electron transport material represented by the general formula (1) is used) Even if it is used repeatedly, unintended black spots are unlikely to occur in the image.

  In other words, the combination of the specific charge generating material, the specific electron transport material, and the phenolic antioxidant as the material to be included in the single-layer type photosensitive layer is repeated by applying a high potential to the surface of the photoconductor. Even if image formation is performed, the occurrence of unintended black spots is suppressed. The reason is not clear, but is presumed to be as follows.

  The occurrence of unintended black spots is assumed to occur as follows. Specifically, when at least one of a plurality of functional materials (charge generation material, hole transport material, and electron transport material) contained in the single-layer type photosensitive layer is unevenly distributed, the surface of the photoreceptor is charged. Sometimes, it is conceivable that charges are concentrated in a region where the functional material is unevenly distributed. When the surface of the photoreceptor is repeatedly charged by applying a high potential, it is presumed that the region where the charge of the photosensitive layer is concentrated is destroyed and appears as an unintended black spot in the formed image.

  On the other hand, in the present embodiment, by combining the specific charge generation material, the hole transport material, and the specific electron transport material with a phenol-based antioxidant, uneven distribution of individual materials is suppressed. Oxidation of the photosensitive layer is also suppressed. That is, in this embodiment, in addition to the conventional anti-oxidation function, the phenol-based anti-oxidant allows each material (such as the electron transport material represented by the general formula (1)) included in the single-layer type photosensitive layer to mutually pass. It is presumed that they are compatible with each other and play a role of dispersing well (a role of dispersing aid). Therefore, when used in combination with charging means for charging the surface potential of the photoreceptor to be in the above range, the intended image density can be easily obtained, and unintended black spots are unlikely to occur in the image even after repeated use. It is estimated that.

The surface potential of the electrophotographic photosensitive member charged by the charging means is 800 V or more and 1200 V or less as described above, and is preferably 800 V or more and 1000 V or less from the viewpoint of achieving both gradation reproducibility and suppression of black spot generation.
The surface potential is measured using a surface potential meter (for example, Trek 334, manufactured by Trek Co.) by installing a surface potential measurement probe so as to face the electrophotographic photosensitive member instead of the developing device.

  The image forming apparatus according to the present embodiment will be described in detail below with reference to the drawings.

FIG. 1 is a schematic configuration diagram illustrating an image forming apparatus according to the present embodiment.
As shown in FIG. 1, the image forming apparatus 101 according to the present embodiment includes, for example, an electrophotographic photosensitive member 10 that rotates clockwise as indicated by an arrow A, and an electrophotographic photosensitive member 10 that A charging device 20 (an example of a charging unit) that is provided relative to the photographic photosensitive member 10 and charges the surface of the electrophotographic photosensitive member 10, and the surface of the electrophotographic photosensitive member 10 charged by the charging device 20 is exposed to light. An exposure device 30 (an example of an electrostatic latent image forming unit) that forms an electrostatic latent image, and a toner contained in a developer is attached to the electrostatic latent image formed by the exposure device 30 to form an electrophotographic photosensitive member 10. A developing device 40 (an example of a developing unit) that forms a toner image on the surface and a recording paper P (an example of a recording medium) are charged to a polarity different from the charging polarity of the toner, and the recording paper P is placed on the electrophotographic photoreceptor 10. Transfer device for transferring toner images Comprising 0, a cleaning device 70 for cleaning the surface of the electrophotographic photosensitive member 10 (an example of a cleaning unit), a. The image forming apparatus 101 according to the present exemplary embodiment includes a fixing device 60 that fixes the toner image while conveying the recording paper P on which the toner image is formed.

  Details of main components in the image forming apparatus 101 according to the present embodiment will be described below.

[Electrophotographic photoreceptor]
FIG. 2 schematically shows a partial cross section of the electrophotographic photoreceptor 10 according to the present exemplary embodiment.
The electrophotographic photoreceptor 10 shown in FIG. 2 includes, for example, a conductive substrate 4, and an undercoat layer 1, a single-layer type photosensitive layer 2, and a protective layer 3 are provided on the conductive substrate 4 in this order. Is configured.
In addition, the undercoat layer 1 and the protective layer 3 are layers provided as necessary.

  Hereinafter, each element of the electrophotographic photoreceptor 10 will be described. 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.

  As a roughening method, for example, wet honing performed by suspending an abrasive in water and spraying it on a support, centerless grinding in which a conductive substrate is pressed against a rotating grindstone, and grinding is continuously performed, Anodizing treatment etc. are mentioned.

  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 a silane coupling agent having an amino group is 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 or 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 titanium chelate compounds include tetraisopropyl titanate, tetranormal butyl titanate, butyl titanate dimer, tetra (2-ethylhexyl) titanate, titanium acetylacetonate, polytitanium acetylacetonate, titanium octylene glycolate, titanium lactate ammonium salt. , Titanium lactate, titanium lactate ethyl ester, titanium triethanolamate, polyhydroxy titanium stearate and the like.

  Examples of the aluminum chelate compound include aluminum isopropylate, monobutoxy aluminum diisopropylate, aluminum butyrate, 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 adjusted from 1 / 4n (n is the refractive index of the upper layer) to 1 / 2λ of the exposure laser wavelength λ used to suppress moire images. It should be done.
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)
The single-layer type photosensitive layer includes a binder resin, a charge generation material, a hole transport material, an electron transport material, an antioxidant, and, if necessary, other additives. .

-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 content of the binder resin with respect to the total solid content of the photosensitive layer may be 20% by mass or more and 70% by mass or less, and preferably 35% by mass or more and 60% by mass or less.

-Charge generation material-
As the charge generation material, at least one selected from hydroxygallium phthalocyanine pigment and chlorogallium phthalocyanine pigment is applied.
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, more preferably 0.01 μm or more and 0.15 μm or less, while the BET specific surface area is preferably 45 m ² / g or more. 50 m ² / g or more, more 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 tend to be coarse or aggregates of the pigment particles tend to be formed. In addition, defects such as dispersibility, sensitivity, chargeability, and dark decay characteristics tend to easily occur, which may easily 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 tend 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 m2 / 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, there is no particular limitation on the chlorogallium phthalocyanine pigment, but Bragg angles (2θ ± 0.2 °) of 7.4 °, 16.6 °, and 25. 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 more preferably 1.2% by mass to 4.5% 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 (4), a compound represented by the following general formula (B-1), and the following general formula (B-2) ) Is desirable. Further, as the hole transport material, a compound represented by the following general formula (4) is particularly desirable from the viewpoint of dispersibility in the photosensitive layer.
First, the compound represented by the following general formula (4) will be described.

In General Formula (4), 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 (4), 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 (4), 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 the general formula (4), 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 (4), 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 (4) 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 (4) will be shown, but not limited thereto. In addition, the following exemplary compound numbers are described as an exemplary compound (4-number) below. Specifically, for example, Exemplified Compound 15 is represented below as “Exemplified Compound (4-15)”.

The abbreviations in the above exemplified 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-PhO : Phenoxy group substituted at 4-position of phenyl group

  Next, the compound (triarylamine derivative) represented by the following general formula (B-1) and the compound (benzidine derivative) represented by the following general formula (B-2) will be described.

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.)

Here, among the triarylamine derivatives represented by the general formula (B-1) and the benzidine derivatives represented by the general formula (B-2), in particular, “—C ₆ H ₄ —CH═CH—CH A triarylamine derivative having “═C (R ^B6 ) (R ^B7 )” and a benzidine derivative having “—CH═CH— ^CH═C (R ^B14 ) (R ^B15 )” are preferred.

  Specific examples of the triarylamine derivative represented by the general formula (B-1) and the benzidine derivative represented by the general formula (B-2) 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 or more and 50% by mass or less, and more preferably 20% by mass or more and 40% by mass or less.
In addition, content of this hole transport material is content of the whole hole transport material, when multiple types of hole transport materials are used together.

-Electron transport material-
As the electron transport material, an electron transport material represented by the general formula (1) is applied.

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

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

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

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

In the general formula (1), examples of the alkyl group represented by R ¹⁸ include a linear alkyl group having 5 to 10 carbon atoms and a branched alkyl group having 5 to 10 carbon atoms.
Examples of the linear alkyl group having 5 to 10 carbon atoms include, for example, a methyl group, an ethyl group, an n-propyl group, an n-butyl group, an n-pentyl group, an n-hexyl group, and an n-heptyl group. , N-octyl group, n-nonyl group, n-decyl group and the like.
Examples of the branched alkyl group having 5 to 10 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, Examples include isooctyl group, sec-octyl group, tert-octyl group, isononyl group, sec-nonyl group, tert-nonyl group, isodecyl group, sec-decyl group, tert-decyl group and the like.

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

In general formula (1), 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 a linear or branched alkylene group having 1 or more carbon atoms, such as a methylene group, an ethylene group, an n-propylene group, an isopropylene group, an n-butylene group, 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, and a dimethylphenyl group.

Specific examples of the aralkyl group represented by R ¹⁸ in the general formula (1) include a benzyl group, a methylbenzyl group, a dimethylbenzyl group, a phenylethyl group, a methylphenylethyl group, a phenylpropyl group, and a phenylbutyl group. Can be mentioned.

As an electron transport material represented by the general formula (1), R ¹⁸ represents an electron having a linear or branched alkyl group having 5 to 10 carbon atoms from the viewpoint of increasing sensitivity and suppressing the generation of black spots. A transport material is preferable, and in particular, R ^{11 to} R ¹⁷ each independently represent a hydrogen atom, a halogen atom, or an alkyl group, and R ¹⁸ is a linear or branched alkyl group having 5 to 10 carbon atoms. An electron transporting material is preferred.

  Hereinafter, although the exemplary compound of the electron transport material represented by the general formula (1) is shown, it is 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)”.

The abbreviations in the above exemplified compounds have the following meanings.
・ Ph: Phenyl group

The content of the electron transport material with respect to the total solid content of the photosensitive layer is preferably 7% by mass or more and 22% by mass or less, and more preferably 10% 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 the electron transport material represented by General formula (1) and another electron transport material are used together.

-Other charge transport materials-
In addition to the hole transport material and the specific electron transport material, other charge transport materials (other electron transport materials) may be used in combination as long as the function is not impaired. However, the other charge transport material is preferably used in an amount of 10% by mass or less based on the whole hole transport material and electron transport material.

  Other charge transport materials include, for example, quinone compounds such as p-benzoquinone, chloranil, bromanyl, anthraquinone, tetracyanoquinodimethane compounds, fluorenone compounds such as 2,4,7-trinitrofluorenone, and xanthone compounds. And electron transporting compounds such as benzophenone compounds, cyanovinyl compounds, and ethylene compounds. These other charge 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 50/50 or more and 90/10 or less, more preferably 60/40 or more and 80/20 or less in terms of mass ratio (hole transport material / electron transport material). is there.
In addition, this ratio is a ratio in total when other charge transport materials are used in combination.

-Antioxidant-
A phenolic antioxidant is applied as the antioxidant. A phenolic antioxidant is an antioxidant having a phenol ring.

As a phenolic antioxidant, the antioxidant which has a hindered phenol ring is mentioned suitably. That is, as a phenolic antioxidant, the following are mentioned, for example.
1) An antioxidant having one phenol ring substituted with at least one alkyl group having 4 to 8 carbon atoms (for example, a branched alkyl group having 4 to 8 carbon atoms).
2) It has 2 or more and 4 or less phenol rings substituted with at least one alkyl group having 4 to 8 carbon atoms (for example, a branched alkyl group having 4 to 8 carbon atoms), and is linear or branched. An ester bond (—C (═O)) between carbon-carbon bonds of a divalent to tetravalent aliphatic hydrocarbon group or a divalent to tetravalent aliphatic hydrocarbon group. An antioxidant in which 2 or more and 4 or less phenol rings are linked by a linking group in which at least one of O-) and an ether bond (-O-) is interposed.

Moreover, as a phenolic antioxidant, the compound which has the phenol ring by which the position of ortho with respect to the phenolic hydroxyl group was substituted by the tertiary alkyl group as a hindered phenol ring is mentioned, for example.
Examples of the number of hindered phenol rings possessed by the phenolic antioxidant include 1 or more and 4 or less, preferably 2 or more and 4 or less, and most preferably 2.
Examples of the phenolic antioxidant having a hindered phenol ring include compounds represented by the following general formulas (A-1) to (A-5).

In the general formula (A-1), R ²¹ represents a tertiary alkyl group having 4 to 7 carbon atoms. R ²² and R ²³ each independently represent a hydrogen atom, a linear alkyl group having 1 to 4 carbon atoms, or a tertiary alkyl group having 4 to 7 carbon atoms. However, at least one of R ²² and R ²³ is a hydrogen atom. R ²⁴ represents a substituted or unsubstituted linear alkyl group having 1 to 4 carbon atoms, a substituted or unsubstituted linear alkoxy group having 1 to 4 carbon atoms, or a hydroxy group.
Examples of the substituent for substituting the linear alkyl group and the alkoxy group in R ²⁴ include an alkoxy group having 1 to 20 carbon atoms, an alkoxycarbonyl group having 1 to 20 carbon atoms, and a phenyl group. It is done.

In the general formulas (A-2) to (A-4), R ³¹ represents a tertiary alkyl group having 4 to 7 carbon atoms. R ³² and R ³³ each independently represent a hydrogen atom, a linear alkyl group having 1 to 4 carbon atoms, or a tertiary alkyl group having 4 to 7 carbon atoms. However, at least one of R ³² and R ³³ is a hydrogen atom. L ³ and L ⁴ are each independently a linear or branched alkylene group having 1 to 4 carbon atoms, or two or more linear or branched alkylene groups having 1 to 7 carbon atoms. A linking group linked via at least one of an ester bond (—C (═O) O—) and an ether bond (—O—).

In the general formula (A-5), R ⁴¹ represents a tertiary alkyl group having 4 to 7 carbon atoms. ^R42 is a hydrogen atom or a linear alkyl group having 1 to 4 carbon atoms. L ⁵ is a linear or branched alkylene group having 1 to 4 carbon atoms, or two or more linear or branched alkylene groups having 1 to 7 carbon atoms in an ester bond (—C (= O) A linking group linked via at least one of O-) and an ether bond (-O-).

In General Formulas (A-2) to (A-5), two or more linear or branched alkylene groups having 1 to 7 carbon atoms represented by L ^{3 to} L ⁵ are ester bonds (—C ( Examples of the linking group linked via at least one of ═O) O—) and an ether bond (—O—) include a linking group represented by the following general formula (A-6).

In General Formula (A-6), R ^{51 to} R ⁵⁴ each independently represent a linear or branched alkylene group having 1 to 7 carbon atoms. * Indicates a connecting part.
Hereinafter, although the exemplary compound of a phenolic antioxidant is shown, it is not necessarily restricted to this.

  Examples of commercially available phenolic antioxidants include “SUMILIER (registered trademark) MDP-S (manufactured by Sumitomo Chemical Co., Ltd.)”, “SUMILIZER (registered trademark) GS (manufactured by Sumitomo Chemical Co., Ltd.), and“ Adeka Stub ”. A0-30 (Asahi Denka Kogyo Co., Ltd.) "," Adeka Stub A0-60 (Asahi Denka Kogyo Co., Ltd.) "and the like.

The addition amount of the phenol-based antioxidant is preferably 1 part by mass or more and 100 parts by mass or less, and preferably 5 parts by mass or more and 50 parts by mass or less with respect to 100 parts by mass of the electron transport material from the viewpoint of easily suppressing the generation of the black spots. The following is more preferable.
Further, the content of the phenolic antioxidant with respect to the solid content of the photosensitive layer is, for example, from 0.5% by mass to 10% by mass, preferably 1% by mass, from the viewpoint of easily suppressing the generation of the black spots. It is 5 mass% or less, More preferably, it is 1 mass% or more and 3 mass% or less.
By setting the content of the phenolic antioxidant within the above range, the deterioration of the electrical characteristics of the electrophotographic photosensitive member is suppressed as compared with the case where the content is too large while suppressing the generation of black spots.

-Other additives-
The single-layer type photosensitive layer may contain other known additives such as 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. Common organic solvents such as cyclic or linear ethers such as ether can be mentioned. 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 groups containing at least one selected from a vinyl group, vinyl ether group, vinyl thioether group, styryl group, acryloyl group, methacryloyl group, and derivatives thereof. Among them, the chain polymerizable group is preferably a group containing at least one selected from a vinyl group, a styryl group, an acryloyl group, a methacryloyl group, and derivatives thereof because of its excellent reactivity. .

  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.

[Charging device]
The charging device 20 is not particularly limited as long as it is charged so that the surface potential of the electrophotographic photosensitive member 10 falls within the above range.
Examples of the charging device 20 include a contact charger using a conductive charging roller, a charging brush, a charging film, a charging rubber blade, a charging tube, and the like. Further, examples of the charging device 20 include a non-contact type roller charger and a known charger such as a scorotron charger using a corona discharge or a corotron charger. In the case of contact charging, the charging device 20 is preferably a non-contact type charger because the generation of black spots may be promoted by the pressing.

[Exposure equipment]
Examples of the exposure apparatus 30 include optical system devices that expose the surface of the electrophotographic photoreceptor 10 with light such as semiconductor laser light, LED light, and liquid crystal shutter light imagewise. The wavelength of the light source is preferably within the spectral sensitivity region of the electrophotographic photoreceptor 10. The wavelength of the semiconductor laser is preferably near infrared having an oscillation wavelength of around 780 nm, for example. 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. As the exposure apparatus 30, for example, a surface-emitting laser light source of a multi-beam output type is also effective for color image formation.

[Developer]
An example of the developing device 40 is a configuration in which a developing roll 41 disposed in the developing region facing the electrophotographic photosensitive member 10 is provided in a container that stores a two-component developer composed of toner and a carrier. The developing device 40 is not particularly limited as long as it is a device that develops with a two-component developer, and a known configuration is employed.

  Here, the developer used in the developing device 40 may be a one-component developer made of toner, or may be a two-component developer including toner and carrier.

[Transfer device]
As the transfer device 50, for example, a contact transfer charger using a belt, a roller, a film, a rubber blade or the like, or a known transfer charger such as a scorotron transfer charger using a corona discharge or a corotron transfer charger. Can be mentioned.

[Cleaning device]
The cleaning device 70 includes, for example, a casing 71, a cleaning blade 72, and a cleaning brush 73 disposed on the downstream side of the cleaning blade 72 in the rotation direction of the electrophotographic photosensitive member 10. Further, for example, a solid lubricant 74 is disposed in contact with the cleaning brush 73.

  Hereinafter, the operation of the image forming apparatus 101 according to the present embodiment will be described. First, the electrophotographic photoreceptor 10 rotates along the direction indicated by the arrow a, and at the same time is positively charged by the charging device 20.

  The electrophotographic photoreceptor 10 whose surface is positively charged by the charging device 20 is exposed by the exposure device 30 to form a latent image on the surface.

  When the portion where the latent image is formed on the electrophotographic photosensitive member 10 approaches the developing device 40, toner is attached to the latent image by the developing device 40 (developing roll 41), and a toner image is formed.

When the electrophotographic photosensitive member 10 on which the toner image is formed is further rotated in the direction of arrow a, the toner image is transferred onto the recording paper P by the transfer device 50. As a result, a toner image is formed on the recording paper P.
Thereafter, the surface of the electrophotographic photosensitive member 10 is cleaned by the cleaning device 70. Then, charging is again performed by the charging device 20, and the next cycle (image process) is performed.

  The toner image is fixed on the recording paper P on which the image is formed by the fixing device 60.

For example, as illustrated in FIG. 3, the image forming apparatus 101 according to the present embodiment includes an electrophotographic photosensitive member 10, a charging device 20, an exposure device 30, a developing device 40, and a cleaning device 70 in a housing 11. May be provided with a process cartridge 101 </ b> A in which are integrally stored. The process cartridge 101A integrally contains a plurality of members and is attached to and detached from the image forming apparatus 101.
The configuration of the process cartridge 101A is not limited to this. For example, the process cartridge 101A only needs to include at least the electrophotographic photosensitive member 10, and may be selected from, for example, the charging device 20, the exposure device 30, the developing device 40, and the cleaning device 70. At least one of the above may be provided.

  In addition, the image forming apparatus 101 according to the present embodiment is not limited to the above configuration, and is, for example, a cleaning device around the electrophotographic photosensitive member 10 and downstream of the transfer device 50 in the rotation direction of the electrophotographic photosensitive member 10. A first neutralization device may be provided on the upstream side of the rotation direction of the electrophotographic photosensitive member from 70 so that the polarity of the remaining toner is aligned and easy to remove with a cleaning brush. Alternatively, a configuration may be adopted in which a second static elimination device for neutralizing the surface of the electrophotographic photosensitive member 10 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 relative to the charging device 20. .

  The image forming apparatus 101 according to the present embodiment is not limited to the above-described configuration, and a known configuration, for example, a toner image formed on the electrophotographic photosensitive member 10 is transferred to the intermediate transfer member and then transferred to the recording paper P. An intermediate transfer type image forming apparatus or a tandem type image forming apparatus may be used.

  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.

<Preparation of Photoreceptor 1>
Bragg angles (2θ ± 0.2 °) of X-ray diffraction spectrum using Cukα characteristic X-ray as a charge generating material are at least 7.3 °, 16.0 °, 24.9 °, 28.0 °. 2 parts by mass of a V-type hydroxygallium phthalocyanine pigment having a diffraction peak, 53 parts by mass of a bisphenol Z polycarbonate resin (viscosity average molecular weight: 50,000) as a binder resin, and the above formula (2) as an antioxidant 1 part by mass of compound and tetrahydrofuran
The mixture consisting of 250 parts by mass was dispersed in a sand mill for 5 hours using glass beads having a diameter of 1 mmφ to obtain a dispersion.
In the resulting dispersion, exemplary compound (4-1) represented by general formula (4) as a hole transport material (indicated as “T-1” in Tables 1 and 2) 32 parts by mass, and electron transport 14 parts by mass of the exemplified compound (1-2) represented by the general formula (1) (indicated as “I-1” in Tables 1 and 2) as a material, and further stirred for 12 hours, photosensitive A layer forming coating solution was obtained.

This photosensitive layer forming coating solution is applied by dip coating onto an aluminum substrate having a diameter of 30 mm and a length of 244.5 mm, followed by drying and curing at 140 ° C. for 30 minutes, and a single-layer type having a thickness of 26 μm. A photosensitive layer was formed.
Through the above steps, an electrophotographic photosensitive member (photosensitive member 1) was produced.

<Preparation of photoconductors 2 to 20>
According to Tables 1 and 2, in the same manner as Photoreceptor 1, except that the types and amounts of charge generation material, binder resin, antioxidant, hole transport material, and electron transport material were changed. 20 was produced.
In Table 1, “parts” indicates parts by mass.

<Examples 1-18, Comparative Examples 1-5>
(Initial image evaluation)
In accordance with Table 3, the obtained electrophotographic photosensitive member (photosensitive member 1 to photosensitive member 20) is mounted on an image forming apparatus (JUSTIO HL2270DW) manufactured by Brother, and charged potential (electrophotographic photosensitive member charged by the charging device). Table 3 shows the potential on the surface) and the development potential (the potential applied to the developing roll, the potential at which the amount of toner developed by the potential difference between the surface potential of the electrophotographic photosensitive member after the exposure and the development potential is controlled). The following initial image evaluation was performed on the image forming apparatus in which the potential was set to the value shown. The results are shown in Table 3.

  Specifically, using the image forming apparatus, a 20% halftone and solid black image is formed in an environment of room temperature 22 ° C. and humidity 55%, and image density (X-Rite 938) is used to measure the image density (X-Rite 938). Dout) was measured and evaluated according to the following criteria.

-Evaluation criteria for 20% halftone images-
A: 0.15 <Dout ≦ 0.25
B: 0.1 <Dout ≦ 0.15 or 0.25 <Dout ≦ 0.3
C: Dout ≦ 0.1 or 0.3 <Dout

-Evaluation criteria for solid black images-
A: 1.4 ≦ Dout
B: 1.35 ≦ Dout <1.4
C: 1.3 ≦ Dout <1.35
D: Dout <1.3

(Maintenance evaluation)
According to Table 3, the obtained electrophotographic photosensitive member (photosensitive member 1 to photosensitive member 20) is mounted on an image forming apparatus (HL2270DW) manufactured by Brother so that the charging potential and the developing potential become the values shown in Table 3. The following maintainability evaluation was performed on the image forming apparatus in which the potential was set. The results are shown in Table 3.

-Evaluation of image quality maintenance-
Specifically, using the above-described image forming apparatus, 2000 images with an image density of 4% are formed in an environment of room temperature 28 ° C. and humidity 85%, and then left for 12 hours, and then a 50% halftone image is formed. The number of black spots in the image was counted and evaluated according to the following criteria. The number of black spots was evaluated according to the following criteria by counting the number of black spots in an image for one week of the electrophotographic photosensitive member.

-Evaluation criteria for image quality maintenance (black spots)-
A: 5 or less black spots with a diameter of less than 0.3 mm and no black spots with a diameter of 0.3 mm or more B: No more than 5 black spots with a diameter of less than 0.3 mm and 1 black spot with a diameter of 0.3 to 0.5 mm C: 8 or less black spots less than Φ0.3 mm and 3 or less black spots of Φ0.3 mm or more and 0.5 mm or less D: 0 or more black spots less than Φ0.3 mm, Φ0.3 mm or more and 0. Four or more black spots of less than 5 mm, or black spots of Φ0.5 mm or more occur

-Potential maintenance evaluation-
The image forming apparatus was further modified for potential measurement. Specifically, a surface potential measurement probe (Trek, Model 555P-1) is installed so as to face the electrophotographic photosensitive member instead of the developing device, and connected to a surface potential meter (Trek, Trek 334). Potential measurement was performed. Next, the surface potential of the photoconductor at the time of solid density output (surface potential of the photoconductor on which a solid density latent image was formed by the exposure device) was measured in an environment of room temperature 28 ° C. and humidity 85%. The potential was VL.
The post-exposure potential VL was measured before and after the image maintainability evaluation, and the difference ΔVL was obtained and evaluated according to the following criteria.

-Evaluation criteria for potential maintenance-
A: ΔVL ≦ 10V
B: 10V <ΔVL ≦ 20V
C: 20V <ΔVL

From the above results, it can be seen that in this embodiment, better results are obtained for the initial image quality evaluation and the image quality maintainability evaluation than the comparative example.
As a result, it can be seen that, in this embodiment, compared to the comparative example, a target image density can be easily obtained, and an unintended black spot is less likely to be generated in the image even after repeated use.

  Hereinafter, details of abbreviations in Tables 1 and 2 will be described.

-Charge generation material-
・ Hydroxygallium phthalocyanine: Bragg angles (2θ ± 0.2 °) of X-ray diffraction spectrum using Cukα characteristic X-ray are at least 7.3 °, 16.0 °, 24.9 °, 28.0 ° V-type hydroxygallium phthalocyanine pigment having a diffraction peak at (maximum peak wavelength in spectral absorption spectrum in wavelength range of 600 nm to 900 nm = 820 nm, average particle size = 0.12 μm, maximum particle size = 0.2 μm, specific surface area Value = 60 m ² / g)
Chlorogallium phthalocyanine: Bragg angles (2θ ± 0.2 °) of X-ray diffraction spectrum using Cukα characteristic X-ray are at least 7.4 °, 16.6 °, 25.5 °, 28.3 ° Chlorogallium phthalocyanine pigment having a diffraction peak (maximum peak wavelength in spectral absorption spectrum in wavelength range of 600 nm to 900 nm = 780 nm, average particle diameter = 0.15 μm, maximum particle diameter = 0.2 μm, specific surface area value = 56 m ² / g)

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

-Antioxidant-
Formula (2): Compound (MDPS) represented by Formula (2)
Formula (3): Compound represented by Formula (3) (SUMILIER (registered trademark) GA-80, manufactured by Sumitomo Chemical Co., Ltd.)
-P-1: The exemplary compound (P-1) of the said phenolic antioxidant
P-4: Exemplary compound (P-4) of the phenolic antioxidant
-P-3: Exemplary compound (P-3) of the phenolic antioxidant
Formula (C-1): Compound represented by the following formula (C-1) Formula (C-2): Compound represented by the following formula (C-2)

-Hole transport material-
T-1: Exemplary compound (4-1) of hole transport material represented by the general formula (4)
* T-2: Exemplary compound (HT-1) of benzidine derivative represented by formula (B-2)
T-3: Exemplary compound (HT-4) of the triarylamine derivative represented by the general formula (B-1)

-Electron transport material-
I-1: Exemplary compound (1-2) of electron transport material represented by general formula (1)
-I-2: Exemplary compound (1-14) of an electron transport material represented by the general formula (1)
I-3: Exemplary compound (1-15) of an electron transport material represented by the general formula (1)
I-4: Electron transport material represented by the following formula (C-3)

DESCRIPTION OF SYMBOLS 1 Undercoat layer, 2 Photosensitive layer, 3 Protective layer, 4 Conductive substrate, 10 Electrophotographic photosensitive member, 11 Case, 20 Charging device, 30 Exposure device, 40 Developing device, 41 Developing roll, 50 Transfer device, 60 Fixing Device, 70 cleaning device, 71 housing, 72 cleaning blade, 73 cleaning brush, 74 lubricant, 101A process cartridge, 101 image forming device, P recording paper

Claims (6)

At least one charge selected from a binder resin, a hydroxygallium phthalocyanine pigment, and a chlorogallium phthalocyanine pigment, comprising: a conductive substrate; and a single layer type photosensitive layer provided on the conductive substrate. An electrophotographic photoreceptor comprising a generating material, a hole transport material, an electron transport material represented by the following general formula (1), and a phenolic antioxidant;
Charging means for charging such that the surface potential of the electrophotographic photosensitive member is 800 V or more and 1200 V or less;
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.

(In the general formula (1), 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 image forming apparatus according to claim 1, wherein the phenolic antioxidant includes an antioxidant represented by the following formula (2).
The image forming apparatus according to claim 1, wherein the phenolic antioxidant includes an antioxidant represented by the following formula (3).
The image forming apparatus according to claim 1, wherein the hole transport material is a hole transport material represented by the following general formula (4).

(In General Formula (4), 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 phenyl group which may have a substituent selected from a lower alkyl group, a lower alkoxy group and a halogen atom, and m and n each independently represent 0 or 1.   5. The image forming apparatus according to claim 1, wherein the phenolic antioxidant is contained in an amount of 5 parts by mass or more and 50 parts by mass or less with respect to 100 parts by mass of the electron transport material. At least one charge selected from a binder resin, a hydroxygallium phthalocyanine pigment, and a chlorogallium phthalocyanine pigment, comprising: a conductive substrate; and a single layer type photosensitive layer provided on the conductive substrate. An electrophotographic photoreceptor comprising a generating material, a hole transport material, an electron transport material represented by the following general formula (1), and a phenolic antioxidant;
Charging means for charging such that the surface potential of the electrophotographic photosensitive member is 800 V or more and 1200 V or less;
And a process cartridge which is detachable from the image forming apparatus.

(In the general formula (1), 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.