JP2016065888A - Electrophotographic photoreceptor, image forming apparatus, and process cartridge - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrophotographic photoreceptor that has suppressed aggregation of a charge generating material.SOLUTION: There is provided an electrophotographic photoreceptor including a single-layer photosensitive layer 2, the photosensitive layer containing a hydroxygallium phthalocyanine pigment (HOGaPC) and a chlorogallium phthalocyanine pigment (ClGaPC), a hole transport material having a specific structure, and an electron transport material having a specific structure, where the content ratio of HOGaPC to ClGaPC is 2:8 to 8:2, and the total content of HOGaPC and ClGaPC is 0.8 to 1.5 mass%.SELECTED DRAWING: Figure 1

Description

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

  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 processes of charging, exposure, development, and transfer.

It is known to use a charge transport material having an improved charge transport capability for the photosensitive layer of an electrophotographic photoreceptor used in such an electrophotographic image forming apparatus.
For example, an electron transport material having a specific molecular structure, improved electron transport properties, and increased sensitivity is known (see Patent Documents 1 and 2). A hole transport material having a specific molecular structure and improved hole transportability is also known (see Patent Document 3). In addition, various materials are known as charge transport materials (see Patent Document 4).

  Furthermore, as the photosensitive layer of the electrophotographic photoreceptor, a binder resin, at least one charge generation material selected from hydroxygallium phthalocyanine pigment and chlorogallium phthalocyanine pigment, a hole transport material having a specific structure, A single-layer type photosensitive layer comprising an electron transport material having a specific structure is also known (see Patent Document 5).

JP-A-6-123981 JP 2005-215679 A JP-A-8-295655 JP 2008-15208 A JP 2013-231867 A

  The object of the present invention is to use a metal-free phthalocyanine pigment, a titanyl phthalocyanine pigment, or a total content of hydroxygallium phthalocyanine pigment and chlorogallium phthalocyanine pigment as one of the two types of charge generation materials used in combination. An object of the present invention is to provide an electrophotographic photosensitive member in which aggregation of charge generating materials in a single-layer type photosensitive layer is suppressed as compared with a case where the content exceeds 5% by mass.

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, which is represented by a binder resin, two kinds of charge generation materials, a hydroxygallium phthalocyanine pigment and a chlorogallium phthalocyanine pigment, represented by the following general formula (1) A hole transport material and an electron transport material represented by the following general formula (2) are included, and the content ratio (mass ratio) of the hydroxygallium phthalocyanine pigment and the chlorogallium phthalocyanine pigment is 2: 8 to 8: 2. A photosensitive layer having a total content of the hydroxygallium phthalocyanine pigment and the chlorogallium phthalocyanine pigment of 0.8% by mass or more and 1.5% by mass or less;
An electrophotographic photoreceptor comprising:

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

(In the general formula (2), 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, or an aryl group. R ¹⁸ represents a linear alkyl group having 5 to 10 carbon atoms.)

The invention according to claim 2
2. The electrophotographic photosensitive member according to claim 1, wherein the photosensitive layer has a total content of the hydroxygallium phthalocyanine pigment and the chlorogallium phthalocyanine pigment of 0.8% by mass or more and 1.2% by mass or less.

The invention according to claim 3
The electrophotographic photoreceptor according to claim 1 or claim 2,
A process cartridge that can be attached to and detached from an image forming apparatus.

The invention according to claim 4
The electrophotographic photosensitive member according to claim 1 or 2,
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:

  According to the invention of claim 1, when a metal-free phthalocyanine pigment is used as one of the two types of charge generating materials used in combination, a titanyl phthalocyanine pigment is used, or the total content of hydroxygallium phthalocyanine pigment and chlorogallium phthalocyanine pigment Compared to a case where the ratio exceeds 1.5% by mass, an electrophotographic photosensitive member in which aggregation of charge generation materials in a single-layer type photosensitive layer is suppressed is provided.

  According to the second aspect of the present invention, the aggregation of the charge generating material in the single-layer type photosensitive layer is compared with the case where the total content of the hydroxygallium phthalocyanine pigment and the chlorogallium phthalocyanine pigment exceeds 1.2% by mass. A suppressed electrophotographic photoreceptor is provided.

  According to the inventions according to claim 3 and claim 4, an electrophotographic photoreceptor using a metal-free phthalocyanine pigment as one of the two types of charge generating materials used in combination, an electrophotographic photoreceptor using a titanyl phthalocyanine pigment, or Process cartridge and image formation capable of forming an image in which the occurrence of point defects is suppressed as compared with the case of applying an electrophotographic photosensitive member in which the total content of hydroxygallium phthalocyanine pigment and chlorogallium phthalocyanine pigment exceeds 1.5% by mass An 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 this 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 chargeable photoreceptor having a conductive substrate and a single-layer type photosensitive layer provided on the conductive substrate.
The photosensitive layer is composed of a binder resin, two kinds of charge generation materials, a hydroxygallium phthalocyanine pigment and a chlorogallium phthalocyanine pigment, a hole transport material represented by the following general formula (1), and the following general formula (2). The electron transport material represented is included. The content ratio (mass ratio) of the hydroxygallium phthalocyanine pigment and the chlorogallium phthalocyanine pigment is 2: 8 to 8: 2, and the total content of the hydroxygallium phthalocyanine pigment and the chlorogallium phthalocyanine pigment is 0.8. The mass is 1.5% by mass or more.

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

(In the general formula (2), 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, or an aryl group. R ¹⁸ represents a linear alkyl group having 5 to 10 carbon atoms.)

  The single-layer type photosensitive layer is a photosensitive layer having hole transporting properties and electron transporting properties as well as charge generation ability.

As the electrophotographic photoreceptor, a single-layer type positively chargeable organic photoreceptor is preferably used from the viewpoint of manufacturing cost and image quality stability. However, since the single-layer type photoreceptor has a structure in which the charge generation material, the hole transport material, and the electron transport material are contained in the same layer, the dispersibility of the charge generation material is affected by the interaction between the materials. There was a tendency peculiar to the single-layer type photoreceptor to be lowered. When the dispersibility of the charge generating material is lowered, the charge generating material is aggregated and tends to cause image quality defects. In particular, when a positively chargeable single-layer type photoconductor is used for an electrophotographic image forming apparatus with a printing speed exceeding 40 sheets per minute, the potential after exposure is increased due to uneven sensitivity characteristics in the surface of the photoconductor. There was a case where point defects (white spots) were not caused.
Incidentally, as means for improving the dispersibility of the charge generating material in the photosensitive layer of the single-layer type photoreceptor, generally, the addition of a dispersion aid, the surface treatment of the charge generating material, the acid of the binder resin and the charge generating material are used. -Stabilization of the dispersion state using base interaction can be considered. However, in all cases, the charge transport property tends to be lowered, that is, there is a trade-off between the characteristics required of the photoreceptor.

On the other hand, in the electrophotographic photosensitive member according to the present embodiment, two types of charge generation materials of a hydroxygallium phthalocyanine pigment and a chlorogallium phthalocyanine pigment are used in combination in a single-layer type photosensitive layer, and the two types of charge generation are performed. By controlling the content ratio and the total content of the materials within the above ranges, aggregation of the charge generation material in the photosensitive layer is suppressed, and the dispersibility of the charge generation material is improved.
The reason for this is not clear, but by using two types of charge generation materials in combination and selecting a hydroxygallium phthalocyanine pigment and a chlorogallium phthalocyanine pigment as the two types, the interaction between the two types of charge generation materials works. Aggregation is considered to be suppressed by the presence of different types of charge generating materials. Moreover, it is thought that said interaction is played favorably because the content ratio of these two kinds of charge generation materials is in the specific range.

  In addition, when the total content rate of said 2 types of charge generation material exceeds the said upper limit, the aggregation inhibitory effect of a charge generation material is not exhibited favorably, but aggregation is suppressed by controlling below the said upper limit. This is because the density is not excessively increased by controlling the content rate within the above range, and the distance between the particles of the charge generating material is maintained in a certain range during the production, and the opportunity of contact between the particles is reduced. Therefore, it is considered that aggregation is suppressed.

Also, by selecting the hole transport material represented by the general formula (1) as the hole transport material and selecting the electron transport material represented by the general formula (2) as the electron transport material. It is considered that the interaction between materials that can reduce the dispersibility of the charge generation material is suppressed. In particular, in the general formula electron transporting material represented by (2), R ¹⁸ is by selecting those which are straight-chain alkyl group having 5 to 10 carbon atoms, R ¹⁸ is not more than 4 carbon atoms straight Compared with the case where it is a chain alkyl group, the case where R ¹⁸ is a linear alkyl group having 11 or more carbon atoms, and the case where R ¹⁸ is a branched alkyl group, aggregation of the charge generating material in the photosensitive layer is reduced. It is suppressed and the dispersibility of the charge generation material is improved.

The total content of the hydroxygallium phthalocyanine pigment and the chlorogallium phthalocyanine pigment in the photosensitive layer is preferably 1.4% by mass or less, more preferably 1.25% by mass, from the viewpoint of further suppressing aggregation of the charge generating material. % Or less is more preferable, and 1.2 mass% or less is still more preferable.
Moreover, as a lower limit, 1.05 mass% or more is further preferable, and 1.15 mass% or more is more preferable.
Further, the content ratio of the hydroxygallium phthalocyanine pigment and the chlorogallium phthalocyanine pigment in the photosensitive layer is more preferably in the range of 4: 6 to 7: 3 from the viewpoint of further suppressing aggregation of the charge generating material. : 4 is more preferable.

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 on the conductive substrate 3 in this order. ing.
The undercoat layer 1 is a layer provided as necessary. Further, other layers may be provided. For example, a protective layer may be further provided in the form of the single-layer type photosensitive layer 2.

  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 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 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 contains other additives as necessary in addition to the binder resin (a), the charge generation material (b), the hole transport material (c), and the electron transport material (d). Consists of.

[Binder resin (a)]
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.

[Charge generating material (b)]
As the charge generation material, two types of hydroxygallium phthalocyanine pigment and chlorogallium phthalocyanine pigment are used in combination.

-Hydroxygallium phthalocyanine pigment Although there is no restriction | limiting in particular as a hydroxygallium phthalocyanine pigment, A V-type hydroxygallium phthalocyanine pigment is good.
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. Desirable from a viewpoint. When used as a material for an electrophotographic photosensitive member, excellent dispersibility and 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 to 839 nm is preferably in a specific range for the average particle size and in a specific range for the BET specific surface area. Specifically, the average particle size is desirably 0.20 μm or less, more desirably 0.01 μm or more and 0.15 μm or less, while the BET specific surface area is desirably 45 m ² / g or more. 50 m ² / g or more is more desirable, and 55 m ² / g or more and 120 m ² / g or less is particularly desirable. The average particle size is a volume average particle size (d50 average particle size) measured by a laser diffraction / scattering particle size distribution analyzer (LA-700, manufactured by Horiba, Ltd.). Moreover, it is the value measured by the nitrogen substitution method using the BET-type specific surface area measuring device (Shimadzu Corporation make: Flow soap II2300).
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, there is a tendency that the pigment particles are coarsened or aggregates of the pigment particles are 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 desirably 1.2 μm or less, more desirably 1.0 μm or less, and more desirably 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 desirably 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 desirable that it is a V type having a diffraction peak.

Chlorogallium phthalocyanine pigment There is no particular limitation on the chlorogallium phthalocyanine pigment, but a Bragg angle (2θ ± 0.2 °) of 7.4 °, 16.6 ° can be obtained which provides excellent sensitivity as an electrophotographic photosensitive material. , 25.5 ° and 28.3 ° having diffraction peaks.
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 total content of the two types of charge generating materials is 0.8% by mass or more and 1.5% by mass or less with respect to the photosensitive layer. When the total content exceeds the upper limit, aggregation of the charge generation layer in the photosensitive layer cannot be satisfactorily suppressed. On the other hand, if it is less than the lower limit, the charge generation ability required for the photoreceptor is not exhibited.
In addition, as an upper limit, 1.4 mass% or less is further preferable, 1.25 mass% or less is more preferable, and 1.2 mass% or less is still more preferable. Moreover, as a lower limit, 1.05 mass% or more is further preferable, and 1.15 mass% or more is more preferable.

The content ratio of the hydroxygallium phthalocyanine pigment and the chlorogallium phthalocyanine pigment in the photosensitive layer is from 2: 8 to 8: 2, more preferably from 4: 6 to 7: 3, and more preferably from 5: 5 to 6 : 4 is more preferable.
When the content ratio is out of the above range, aggregation of the charge generation layer in the photosensitive layer cannot be satisfactorily suppressed.

[Hole transport material (c)]
As the hole transport material, a hole transport material represented by the following general formula (1) is applied.

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. The phenyl group which may have 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.
The “lower” in the lower alkyl group and the lower alkoxy group means that the number of carbon atoms is 4 or less.

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.
Of 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; -Lower alkoxy group-substituted phenyl group such as methoxyphenyl group; and halogen atom-substituted phenyl group such as 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. Are each independently a hydrogen atom, a lower alkyl group, or an alkoxy group, and a hole transport material in which m and n are 1 is desirable.

  Hereinafter, exemplary compounds (1-1) to (1-64) of the hole transport material represented by the general formula (1) will be shown, but not limited thereto.

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-PhO : Phenoxy group substituted at 4-position of phenyl group

  The content of the hole transport material is, for example, 10% by mass to 98% by mass with respect to the binder resin, desirably 60% by mass to 95% by mass, and more desirably 70% by mass to 90% by mass. It is.

[Electron transport material (d)]
As the electron transport material, an electron transport material represented by the following general formula (2) is applied.

In general formula (2), 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 aralkyl group, or An aryl group is shown. R ¹⁸ represents a linear alkyl group having 5 to 10 carbon atoms.

In the general formula (2), 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 (2), 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 (2), 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 (2), examples of the aralkyl group represented by R ^{11 to} R ¹⁷ include a group represented by —R ¹⁹ —Ar ¹ . However, R ¹⁹ represents an alkylene group, and Ar ¹ represents an aryl group. Specifically, a benzyl group etc. are mentioned, for example.

In the general formula (2), examples of the aryl group represented by R ^{11 to} R ¹⁷ include a phenyl group and a tolyl group.
Among these, a phenyl group is desirable.

In the general formula (2), the linear alkyl group having 5 to 10 carbon atoms represented by R ¹⁸ includes an n-pentyl group, an n-hexyl group, an n-heptyl group, an n-octyl group, and an n-nonyl group. , N-decyl group.

As the electron transport material represented by the general formula (2), from the viewpoint of high sensitivity and suppression of image point defects, in particular, R ^{11 to} R ¹⁷ are each independently a hydrogen atom, a halogen atom, or an alkyl group. An electron transport material in which R ¹⁸ represents a linear alkyl group having 5 to 10 carbon atoms is desirable.

  Hereinafter, exemplary compounds (2-1) to (2-10) of the electron transport material represented by the general formula (2) will be shown, but not limited thereto.

  The content of the electron transport material is, for example, 10% by mass to 70% by mass with respect to the binder resin, desirably 15% by mass to 50% by mass, and more desirably 20% by mass to 40% by mass. is there.

[Other charge transport materials]
In addition to the specific hole transport material and electron transport material, other charge transport materials (other hole 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 40% 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. , Electron transport compounds such as benzophenone compounds, cyanovinyl compounds, ethylene compounds, triarylamine compounds, benzidine compounds, arylalkane compounds, aryl-substituted ethylene compounds, stilbene compounds, anthracene compounds, hydrazone compounds And hole transporting compounds such as compounds. These other charge transport materials may be used alone or in combination of two or more, but are not limited thereto.

  Other charge transport materials are preferably a triarylamine derivative represented by the following structural formula (B-1) and a benzidine derivative represented by the following structural formula (B-2) from the viewpoint of charge mobility.

In Structural 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 Structural 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 an alkoxy having 1 to 5 carbon atoms. Group. 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 an alkoxy group having 1 to 5 carbon atoms. , 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 ) (R ^B15 ), and R ^{B11 to} R ^B15 each independently represents a hydrogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aryl group. m12, m13, n12 and n13 each independently represent an integer of 0 or more and 2 or less.

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

-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.

[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. Common organic solvents such as cyclic or linear ethers such as ether may 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.

[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 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.

  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.

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.
The “parts” and “%” shown below are based on mass unless otherwise specified.

[Example 1]
<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 °. A Bragg angle (2θ ± 0.2 °) of an X-ray diffraction spectrum using a hydroxygallium phthalocyanine pigment (HOGaPC) having a diffraction peak and a Cukα characteristic X-ray is at least 7.4 °, 16.6 °, 25.5. Chlorogallium phthalocyanine pigment (ClGaPC) 1.2 parts (HOGaPC: ClGaPC = 5: 5 (mass ratio)) having a diffraction peak at a position of °, 28.3 °, and bisphenol Z polycarbonate resin (viscosity average) as a binder resin (Molecular weight: 50,000) 46.8 parts, 15 parts of the electron transport material shown in Table 1, 37 parts of the hole transport material shown in Table 1, and tetrahydro as the solvent A mixture comprising 250 parts of furan was dispersed for 4 hours in a sand mill using glass beads having a diameter of 1 mmφ to obtain a coating solution for forming a photosensitive layer.
This photosensitive layer forming coating solution is applied by dip coating on 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 to obtain a single-layer type having a thickness of 30 μm. A photosensitive layer was formed.
Through the above steps, an electrophotographic photosensitive member (photosensitive member 1) in Example 1 was produced.

[Examples 2 to 20, Comparative Examples 1 to 18]
<Production of photoconductors 2 to 20 and comparative photoconductors 1 to 18>
According to Tables 1 and 2, electrophotographic photosensitivity is the same as that of Photoreceptor 1 except that the types and amounts of the charge generation material, the electron transport material, the hole transport material, and the binder resin (binder resin) are changed. The body was made. The obtained photoreceptors 2 to 20 and comparative photoreceptors 1 to 18 were used as electrophotographic photoreceptors in Examples and Comparative Examples, respectively.
In Tables 1 and 2, “part” indicates part by mass, and “ratio” indicates the content ratio (mass ratio) of the charge generation material.

<Evaluation>
The electrophotographic photosensitive member obtained as described above was evaluated as follows. The results are summarized in Tables 1 and 2.

-Dispersibility of charge generation materials-
The dispersibility of the charge generation material was evaluated using the following particle scattering coefficient.
The “particle scattering coefficient” in the present embodiment is obtained by dividing the amount of change in absorbance at 1000 nm per 1 μm film thickness of the photosensitive layer by the number of parts by mass of the charge generating material that is the main component of scattering. It is an indicator.
When the value of the particle scattering coefficient is large, the dispersibility of the charge generating material is poor. In particular, when the particle scattering coefficient is 0.017 or more, image quality defects are likely to occur due to aggregation of pigments in the photosensitive layer.

Here, the method for calculating the particle scattering coefficient will be described in detail below.
First, prepare a coating solution for a sample similar to the coating solution for forming a photosensitive layer used when producing a photoreceptor, apply this on a glass plate, and dry and cure under the same conditions when forming the photosensitive layer, A film having a certain thickness (L1 (μm)) was produced. Similarly, films having different thicknesses from L1 (L2 (μm) and L3 (μm)) were formed on a glass plate.
For the three samples thus obtained, the absorbance at 1000 nm was measured, and the values were determined as “A1” for the sample with the film thickness L1, “A2” for the sample with the film thickness L2, and the film thickness L3. In the case of the sample, it was set as “A3”.
Then, the slope of the tangent line was calculated from a plot with the horizontal axis representing the film thickness and the vertical axis representing the absorbance, and the value obtained by dividing the slope by the number of parts by mass of the charge generating material was defined as the particle scattering coefficient.
The film thickness formed on the glass plate was in the range of 5 μm to 15 μm.
Moreover, the light absorbency was measured using the Hitachi make and ultraviolet visible spectrophotometer U2000.

  There is also a method for obtaining the “particle scattering coefficient” from the photosensitive layer of the electrophotographic photosensitive member. As this method, the photosensitive layer is peeled off from the conductive substrate to form a film, and then the “particle scattering coefficient” is obtained by the above method. The photosensitive layer is dissolved in a good solvent, and the solution is used to make a glass plate. There is a method of forming a film upward and obtaining the “particle scattering coefficient” by the above method.

-Evaluation of sensitivity of photoconductor-
The sensitivity of the photoconductor was evaluated as a half exposure amount when charged to + 800V.
Specifically, using an electrostatic copying paper test apparatus (electrostatic analyzer EPA-8100, manufactured by Kawaguchi Electric Co., Ltd.), after charging to +800 V in an environment of 20 ° C. and 40% RH, the light of the tungsten lamp is The monochromator was used to make monochromatic light of 800 nm, adjusted to 1 μW / cm ² on the surface of the photoreceptor, and irradiated.
Then, the surface potential V ₀ (V) on the surface of the photoconductor immediately after charging, and the half exposure amount E1 / 2 (μJ / cm ² ) at which the surface potential becomes 1/2 × V _O (V) by light irradiation on the surface of the photoconductor. Was measured.
Note that the sensitivity of the photoreceptor is evaluated to be high when a half exposure amount of 2.0 μJ / cm ² or less is obtained.

-Image quality evaluation (image quality defects)-
The image quality evaluation was performed on a HL2270DW manufactured by Brother using a modified machine equipped with the electrophotographic photosensitive member obtained as described above.
Using this modified machine, a 50% halftone image was printed, and the point defect of the image was evaluated according to the criteria shown in Table 3. As the details of the evaluation method, the point defects of the obtained image are classified into three sizes, and the evaluation that the number of point defects of each size is the worst with respect to the reference is given.
The evaluation criteria are as shown in Table 3 below. It should be noted that if the evaluation standard is “5” or less, it is evaluated that a problem may occur in practice.

  According to Tables 1 and 2, the electrophotographic photosensitive member of this example is superior in the dispersibility of the charge generating material as compared with the electrophotographic photosensitive member of the comparative example, and the sensitivity of the photosensitive member and evaluation of point defects are evaluated. It can be seen that good results are obtained.

Hereinafter, details of abbreviations in Tables 1 and 2 will be described.
-Electron transport material-
(2-1) to (2-10): exemplary compound of electron transport material represented by general formula (2) Compound A: electron transport material having the following structure Compound B: electron transport material / compound having the following structure C: Electron transport material / compound 1 having the following structure: In general formula (2), R ^{11 to} R ¹⁷ = H, R ¹⁸ = n—C ₄ H ₉ electron transport material / compound 2: in general formula (2) , R ^{11 to} R ¹⁷ = H, R ¹⁸ = n-C ₁₁ H ₂₃ electron transport material / compound 3: In general formula (2), R ^{11 to} R ¹⁷ = H, R ¹⁸ = 2-ethylhexyl group electron Transport material

-Hole transport material-
(1-1), (1-21), (1-22), (1-41), (1-42): Exemplified compounds of the hole transport material represented by the general formula (1) : N, N′-diphenyl-N, N′-bis (3-methylphenyl)-[1,1 ′] biphenyl-4,4′-diamine (hole transport material)

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

-Charge generation material-
・ HOGaPC: X-ray diffraction spectrum using Cukα characteristic X-rays is diffracted at Bragg angles (2θ ± 0.2 °) 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: X-ray diffraction spectrum using Cukα characteristic X-rays is diffracted at Bragg angles (2θ ± 0.2 °) of at least 7.4 °, 16.6 °, 25.5 ° and 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)
H ₂ PC (x-type): Metal-free phthalocyanine pigment (phthalocyanine in which two hydrogen atoms coordinate to the center of the phthalocyanine skeleton)
・ TiOPC (Type II): Titanyl phthalocyanine pigment

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

Claims (4)

A conductive substrate;
A single-layer type photosensitive layer provided on the conductive substrate, which is represented by a binder resin, two kinds of charge generation materials, a hydroxygallium phthalocyanine pigment and a chlorogallium phthalocyanine pigment, represented by the following general formula (1) A hole transport material and an electron transport material represented by the following general formula (2) are included, and the content ratio (mass ratio) of the hydroxygallium phthalocyanine pigment and the chlorogallium phthalocyanine pigment is 2: 8 to 8: 2. A photosensitive layer having a total content of the hydroxygallium phthalocyanine pigment and the chlorogallium phthalocyanine pigment of 0.8% by mass or more and 1.5% by mass or less;
An electrophotographic photoreceptor comprising:


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


(In the general formula (2), 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, or an aryl group. R ¹⁸ represents a linear alkyl group having 5 to 10 carbon atoms.)   The electrophotographic photosensitive member according to claim 1, wherein the photosensitive layer has a total content of the hydroxygallium phthalocyanine pigment and the chlorogallium phthalocyanine pigment of 0.8% by mass or more and 1.2% by mass or less. The electrophotographic photoreceptor according to claim 1 or claim 2,
A process cartridge that can be attached to and detached from an image forming apparatus. The electrophotographic photosensitive member according to claim 1 or 2,
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: