JP2016180899A - Electrophotographic photoreceptor, process cartridge, and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrophotographic photoreceptor that reduces wear of a photosensitive layer.SOLUTION: An electrophotographic photoreceptor includes a single layer type photosensitive layer which contains a binder resin, a charge generating material, a hole transporting material and an electron transporting material represented by general formula (1). A glass transition temperature Tg(A) of the photosensitive layer after the photosensitive layer is subjected to a wear test while a voltage is applied to a surface of the electrophotographic photoreceptor is at least 0.5°C lower than Tg(B) of the photosensitive layer before the test.SELECTED DRAWING: Figure 1

Description

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

  In a conventional electrophotographic image forming apparatus, a toner image formed on the surface of an electrophotographic photosensitive member is transferred to a recording medium through 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).

  Further, as an electrophotographic photosensitive member used in an electrophotographic image forming apparatus, for example, Patent Document 3 discloses that “a photosensitive layer containing a hole transporting agent, a charge generating agent and a binder resin is provided on a substrate. An electrophotographic photoreceptor, wherein the hole transporting agent is a specific hydrazone compound and the photosensitive layer contains a specific compound as an additive. Has been

  Patent Document 4 states that “an electrophotographic photosensitive member having a photosensitive layer containing at least a charge generating agent, a hole transporting agent, and a binder resin on a conductive substrate, wherein the binder resin is used. And a plurality of polycarbonate resins, and the photosensitive layer contains a specific biphenyl derivative as a plasticizer component.

  Patent Document 5 discloses an electrophotographic photosensitive member having a single-layer type photosensitive layer containing a specific material composed of a charge generation material, a hole transport material, and an electron transport material together with a binder resin. .

JP-A-6-123981 JP 2005-215679 A JP 2008-224734 A JP 2007-102199 A JP 2013-231867 A

  An object of the present invention is to provide an electrophotographic photosensitive member having a single-layer type photosensitive layer containing a binder resin, a charge generating material, a hole transporting material, and an electron transporting material represented by the general formula (1). In the above, the glass transition temperature Tg (A) of the photosensitive layer after performing the abrasion test in which the photosensitive layer is worn by 2.0 μm while applying a voltage to the surface of the electrophotographic photosensitive member is the photosensitivity before performing the abrasion test. It is an object of the present invention to provide an electrophotographic photosensitive member that reduces the abrasion of the photosensitive layer as compared with the case where the temperature is 0.5 ° C. higher than the glass transition temperature Tg (B) of the layer or lower than 0.5 ° C.

  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 and including a binder resin, a charge generation material, a hole transport material, and an electron transport material represented by the following general formula (1);
Have
The glass transition temperature Tg (A) of the photosensitive layer after performing a wear test in which the photosensitive layer is worn by 2.0 μm while applying a voltage to the surface of the electrophotographic photosensitive member is the value before the wear test is performed. An electrophotographic photosensitive member that is 0.5 ° C. or more lower than the glass transition temperature Tg (B) of the photosensitive layer.

(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, R ¹⁸ represents an alkyl group, —L ¹⁹ —O—R ²⁰ , an aryl group, or an aralkyl group, provided that L ¹⁹ represents an alkylene group and R ²⁰ represents an alkyl group.

The invention according to claim 2
The electrophotographic photosensitive member according to claim 1, wherein the hole transport material is a hole transport material represented by the following general formula (2).

(In General Formula (2), 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 p and q each independently represent 0 or 1.)

The invention according to claim 3
The electrophotographic photosensitive member according to claim 1 or 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 first aspect of the invention, there is provided a single-layer type photosensitive layer including a binder resin, a charge generation material, a hole transport material, and an electron transport material represented by the following general formula (1). The glass transition temperature Tg (A) of the photosensitive layer after conducting a wear test in which the photosensitive layer is worn by 2.0 μm while applying a voltage to the surface of the electrophotographic photosensitive member. There is provided an electrophotographic photoreceptor that reduces the wear of the photosensitive layer as compared to the case where the temperature is higher than the glass transition temperature Tg (B) of the photosensitive layer before execution or lower than 0.5 ° C.
According to the second aspect of the present invention, an electrophotographic photosensitive member having higher sensitivity is provided as compared with the case where the hole transport material is a hole transport material having two triarylamine structures.

  According to the invention of claim 3 or 4, an electron having a single-layer type photosensitive layer including a charge generation material, a hole transport material, and an electron transport material represented by the following general formula (1) In the photographic photosensitive member, the glass transition temperature Tg (A) of the photosensitive layer after performing the abrasion test in which the photosensitive layer is worn by 2.0 μm while applying a voltage to the surface of the electrophotographic photosensitive member performs the abrasion test. A process cartridge or an image forming apparatus that reduces wear of the photosensitive layer as compared with a case where an electrophotographic photosensitive member that is higher than the glass transition temperature Tg (B) of the previous photosensitive layer or lower in the range of less than 0.5 ° C. is provided. 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 includes a positively charged organic photoreceptor (hereinafter simply referred to as “photoreceptor” or “single-layer photoreceptor”) that includes a conductive substrate and has a single-layer type photosensitive layer on the conductive substrate. Is sometimes called).
The single-layer type photosensitive layer is also referred to as a binder resin, a charge generation material, a hole transport material, and an electron transport material represented by the general formula (1) (hereinafter also referred to as “electron transport material of the formula (1)”). ) And.
The electrophotographic photosensitive member according to this embodiment has a glass transition temperature Tg (A) of the photosensitive layer after performing a wear test in which the photosensitive layer is worn by 2.0 μm while applying a voltage to the surface of the photosensitive member. The glass transition temperature Tg (B) of the photosensitive layer before the wear test is 0.5 ° C. or more lower.

Here, the single-layer type photoreceptor has a structure in which the single-layer type photosensitive layer includes a charge generation material, a hole transport material, and an electron transport material, and thus an organic photoreceptor having a multilayered photosensitive layer. The sensitivity is not so high, and further higher sensitivity is required.
In this regard, the electron transport material of the formula (1) has a high electron transport capability, and the single layer type photosensitive layer containing the electron transport material of the formula (1) is easily increased in sensitivity.

  However, it has been found that the electron transport material of the formula (1) functions to lower the glass transition temperature of the single-layer type photosensitive layer. For this reason, reduction of abrasion of the single-layer type photosensitive layer containing the electron transport material of the formula (1) has also been demanded.

  Therefore, in a single layer type photoreceptor having a single layer type photosensitive layer containing the electron transport material of the formula (1), a wear test was performed in which the photosensitive layer was worn by 2.0 μm while applying a voltage to the surface of the photoreceptor. The glass transition temperature Tg (A) of the subsequent photosensitive layer is made 0.5 ° C. or more lower than the glass transition temperature Tg (B) of the photosensitive layer before the wear test is performed. As a result, the electrophotographic photoreceptor according to the exemplary embodiment reduces the wear of the photosensitive layer. The reason is estimated as follows.

  First, the photosensitive layer in which the glass transition temperature Tg (A) of the photosensitive layer after carrying out the abrasion test is lower by 0.5 ° C. or more than the glass transition temperature Tg (B) of the photosensitive layer before carrying out the abrasion test is The photosensitive layer after abrasion is considered to have a higher content ratio of the electron transport material of the formula (1) than before abrasion. That is, it is considered that the surface layer portion of the photosensitive layer before abrasion has a lower content ratio of the electron transport material of the formula (1) and a higher content ratio of the binder resin than the inside. That is, it is considered that the decrease in the glass transition temperature due to the electron transport material of the formula (1) is suppressed in the surface layer portion of the photosensitive layer before abrasion. For this reason, even in a single layer type photosensitive layer containing the electron transport material of the formula (1), it can be considered that the abrasion resistance derived from the binder resin is easily developed in the surface layer portion of the photosensitive layer.

  From the above, it is presumed that the abrasion of the photosensitive layer is reduced in the electrophotographic photoreceptor according to the exemplary embodiment.

  In the electrophotographic photoreceptor according to the exemplary embodiment, since the wear of the photosensitive layer is reduced, exposure of components (charge generation material, hole transport material, electron transport material, etc.) contained in the photosensitive layer due to the progress of wear. Is suppressed. When a component is exposed from the photosensitive layer, current concentrates on the exposed portion and current leakage (current leakage) is likely to occur. A black spot may occur in an image at a location where current leakage (current leakage) occurs. For this reason, in the electrophotographic photosensitive member according to this embodiment, the occurrence of black spots is easily suppressed.

Here, in the electrophotographic photoreceptor according to the exemplary embodiment, the glass transition temperature Tg (A) of the photosensitive layer after the wear test is performed is the glass transition temperature Tg (B) of the photosensitive layer before the wear test is performed. 0.5 ° C. or more, and from the viewpoint of reducing the wear of the photosensitive layer and increasing the sensitivity of the photosensitive layer, it is preferably 3.0 ° C. or more and 0.75 ° C. or less. It is preferable that it becomes low in the range of 1.0 ° C. or less.
That is, the glass transition temperature of the photosensitive layer before and after the abrasion test satisfies the following relational expression (1), and preferably satisfies the following relational expression (2) from the viewpoint of reducing the wear of the photosensitive layer and increasing the sensitivity of the photosensitive layer. It is more preferable that the following relational expression (3) is satisfied.
-Relational expression (1): Tg (A) -Tg (B) ≦ −0.5 ° C.
Relational expression (2): −3.0 ° C. ≦ Tg (A) −Tg (B) ≦ −0.75 ° C.
Relational expression (3): −2.0 ° C. ≦ Tg (A) −Tg (B) ≦ −1.0 ° C.

  The glass transition temperature of the photosensitive layer before the abrasion test is preferably 75 ° C. or higher and 110 ° C. or lower, more preferably 85 ° C. or higher and 105 ° C. or lower, and more preferably 100 ° C. or higher and 105 ° C. or lower from the viewpoint of reducing the wear of the photosensitive layer. preferable.

  As a method of relating the glass transition temperature of the photosensitive layer before and after the abrasion test, the method of adjusting (reducing) the amount of the electron transport material of the formula (1) and the formation conditions (for example, drying conditions) of the photosensitive layer are adjusted. And the like. Thereby, in the surface layer part of the photosensitive layer before abrasion, the content ratio of the electron transport material of the formula (1) is low and the content ratio of the binder resin is likely to be high.

The glass transition temperature of the photosensitive layer is a value measured by the following method.
First, a measurement sample is collected from a single-layer type photosensitive layer from a photoreceptor to be measured. In addition, you may produce a measurement sample using the coating liquid for single layer type photosensitive layer formation.
Next, using the measurement sample, the dynamic elasticity is measured by a dynamic viscoelasticity measuring apparatus DMS6100 (manufactured by Seiko Instruments Inc.), and the peak temperature of the average loss elastic modulus E ″ is obtained as the glass transition temperature. Is a condition in which the temperature is raised from 35 ° C. to 50 ° C. in a tensile mode, a frequency of 0.5 Hz, and a heating rate of 10 ° C./min.

The abrasion test of the photosensitive layer is a test performed by the following method.
A conductive rubber roll is brought into contact with the photoreceptor. Next, while applying a voltage from the conductive rubber roll to the surface of the photoconductor, the photoconductor is rotated and the conductive rubber roll is driven to rotate. The rotation of the photosensitive member is continued, and the rotation of the photosensitive member is stopped when the wear amount of the photosensitive layer reaches 2.0 μm. This completes the wear test. Detailed test conditions are as follows.
・ Rotational speed of photoconductor: 60 rpm
-Applied voltage to the surface of the photoreceptor: 800V
Conductive rubber roll: A rubber roll in which a conductive elastic layer of 5.0 mm is formed on a shaft of 8 mm in diameter made of stainless steel.
-Surface hardness of conductive rubber roll (Asker C hardness as measured by Asker C hardness meter, manufactured by Kobunshi Keiki Co., Ltd., type C hardness described in JIS K-7312 (1996) Appendix 2): 65 °
-Surface roughness measured by a surface roughness profile measuring machine Surfcom 1400, manufactured by Tokyo Seimitsu Co., Ltd., in a method based on the ten-point average roughness Rz (JIS B0601 (1994)) of the surface of the conductive rubber roll. The measurement conditions are cut-off: 0.8 mm, measurement length: 2.4 mm, traverse speed: 0.3 mm / s.): 6.0 μm
-Contact pressure between the conductive rubber roll and the photoconductor: 9.0 N / mm

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

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

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

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

  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 more preferable.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

The undercoat layer preferably has a Vickers hardness of 35 or more.
The surface roughness (ten-point average roughness) of the undercoat layer is 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, an electron transport material, and a hole transport material. The single layer type photosensitive layer may contain other additives as required.

-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, polycarbonate resin, polyarylate resin, and polyester resin are particularly preferable from the viewpoint of reducing wear of the photosensitive layer, and polycarbonate resin is more preferable. The photosensitive layer containing a polycarbonate resin tends to have a low glass transition temperature due to the charge transport material of formula (1), and the wear of the photosensitive layer is likely to progress. It becomes easy to be suppressed.

In addition, the viscosity average molecular weight of the binder resin is preferably 40,000 or more and 70,000 or less, and more preferably 50,000 or more and 60,000 or less, from the viewpoint of reducing wear of the photosensitive layer.
In addition, the measurement of a viscosity average molecular weight is a value measured by the following method. First, 1 g of resin is dissolved in 100 cm ³ of methylene chloride, and its specific viscosity ηsp is measured with an Ubbelohde viscometer in a measurement environment at 25 ° C. Then, the intrinsic viscosity [η] (cm ³ / g) is determined from the relational expression of ηsp / c = [η] +0.45 [η] ² c (where c is the concentration (g / cm ³ )). The viscosity average molecular weight Mv is determined from the equation given by Schnell, [η] = 1.23 × 10 ⁻⁴ Mv 0.83, and the above one-point measurement method is used.

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

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

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

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

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

  Here, the charge generating material is preferably at least one selected from hydroxygallium phthalocyanine pigments and chlorogallium phthalocyanine pigments, more preferably hydroxygallium phthalocyanine pigments, from the viewpoint of increasing the sensitivity of the single-layer type photoreceptor.

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. Desirable from a 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 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, 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 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 m ² / g or more.

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

On the other hand, as the chlorogallium phthalocyanine pigment, for example, a Bragg angle (2θ ± 0.2 °) of 7.4 °, 16.6 °, 25.5 °, and 28 can be obtained with excellent sensitivity as an electrophotographic photosensitive material. It is desirable to have a diffraction peak at 3 °.
In addition, 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 or more and 5% by mass or less, and preferably 1.2% by mass or more and 4.5% by mass or less.

-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 (2) (hereinafter also referred to as “hole transport material of formula (2)”), the following general formula (B- The compound represented by 1), the compound represented by the following general formula (B-2), and the compound represented by the general formula (B-3) are preferable. Among these, the hole transport material of the formula (2) is particularly preferable from the viewpoint of increasing the sensitivity of the single layer type photoreceptor.

In general formula (2), 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. p and q each independently represent 0 or 1. )

In the general formula (2), examples of the lower alkyl group represented by R ^{1 to} R ⁶ include a linear or branched alkyl group having 1 to 4 carbon atoms. 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 (2), 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 (2), 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 (2), 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 p-tolyl group and 2,4-dimethylphenyl group; p -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, a lower alkoxy group, and a halogen atom represented by R ^{1 to} R ⁶ .

Among the hole transport materials represented by the formula (2), a hole transport material in which p and q are 1 is preferable from the viewpoint of increasing the sensitivity of the single layer type photoreceptor, and R ^{1 to} R ⁶ are each independently hydrogen. A hole transport material which represents an atom, a lower alkyl group, or an alkoxy group, and p and q are 1 is more preferable.

  Hereinafter, although the exemplary compound of the hole transport material of Formula (2) is shown, it is not necessarily limited to this. In addition, the following exemplary compound numbers are described as an exemplary compound (2-number) below. Specifically, for example, Exemplified Compound 15 is represented below as “Exemplified Compound (2-15)”.

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

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 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 are each independently a halogen atom, an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, or a carbon number. An amino group substituted with 1 or more and 2 or less alkyl groups, a substituted or unsubstituted aryl group, -C (R ^B11 ) = C (R ^B12 ) (R ^B13 ), or -CH = CH-CH = C (R ^B14 ) (R ^B15 ), and R ^{B11 to} R ^B15 each independently represent 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.

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

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

  Here, specific examples of the compound represented by the general formula (B-1), the compound represented by the general formula (B-2), and the compound represented by the general formula (B-3) include, for example, the following compounds: Can be mentioned.

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 40% by mass or less, and preferably 20% by mass or more and 35% by mass or less.
In addition, content of this hole transport material is content of those whole hole transport materials, when 2 or more types of hole transport materials are used together.

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

In 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 An aralkyl group is shown. R ¹⁸ represents an alkyl group, —L ¹⁹ —O—R ²⁰ , an aryl group, or an aralkyl group. ^{However, L 19} represents an alkylene ^{group, R 20} represents an alkyl 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. Among these, as the aryl group represented by R ^{11 to} R ¹⁷ , a phenyl group is preferable.
In general formula (1), examples of the aralkyl group represented by R ^{11 to} R ¹⁷ include a benzyl group, a phenethyl group, and a phenylpropyl group.

In general formula (1), examples of the alkyl group represented by R ¹⁸ include a linear alkyl group having 1 to 15 carbon atoms (preferably 3 to 12 carbon atoms), and 3 to 15 carbon atoms (preferably Is a branched alkyl group having 3 to 12 carbon atoms.
Examples of the linear alkyl group having 1 to 15 carbon atoms include, for example, methyl group, ethyl group, n-propyl group, n-butyl group, n-pentyl group, n-hexyl group, n-heptyl group, n -An octyl group, n-nonyl group, n-decyl group, n-undecyl, n-dodecyl etc. are mentioned.
Examples of the branched alkyl group having 3 to 15 carbon atoms include isopropyl group,
Isobutyl group, sec-butyl group, tert-butyl group, isopentyl group, neopentyl group, tert-pentyl group, isohexyl group, sec-hexyl group, tert-hexyl group, isoheptyl group, sec-heptyl group, tert-heptyl group, 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), a group represented by ^-L 19 ^{-O-R 20} represented by ^{R 18 is L 19} represents an alkylene ^{group, R 20} represents an alkyl group.
Examples of the alkylene group represented by L ¹⁹ include linear or branched alkylene groups having 1 to 12 carbon atoms, and include a methylene group, an ethylene group, an n-propylene group, an isopropylene group, an n-butylene group, and an isobutylene. Group, sec-butylene group, tert-butylene group, n-pentylene group, isopentylene group, neopentylene group, tert-pentylene group and the like.
Examples of the alkyl group represented by R ²⁰ include the same groups as the alkyl groups represented by R ^{11 to} R ¹⁷ .

In the general formula (1), examples of the aryl group represented by R ¹⁸ include a phenyl group, a methylphenyl group, a dimethylphenyl group, and an ethylphenyl group.
The aryl group represented by R ¹⁸ is preferably an alkyl-substituted aryl group substituted with an alkyl group from the viewpoint of solubility. Examples of the alkyl group of the alkyl-substituted aryl group include the same groups as the alkyl groups represented by R ^{11 to} R ¹⁷ .

In general formula (1), examples of the aralkyl group represented by R ¹⁸ include a group represented by —R ^18A —Ar. R ^18A represents an alkylene group, and Ar represents an aryl group.
^Examples of the alkylene group represented by R ^18A include linear or branched alkylene groups having 1 to 12 carbon atoms, and include a methylene group, an ethylene group, an n-propylene group, an isopropylene group, an n-butylene group, and an isobutylene. Group, sec-butylene group, tert-butylene group, n-pentylene group, isopentylene group, neopentylene group, tert-pentylene group and the like.
Examples of the aryl group represented by Ar include a phenyl group, a methylphenyl group, a dimethylphenyl group and an ethylphenyl 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. .

As an electron transport material of the formula (1), from the viewpoint of increasing the sensitivity of a single-layer type photosensitive layer and reducing wear, an electron transport material in which R ¹⁸ represents an alkyl group or an aralkyl group having 3 to 12 carbon atoms is used. In particular, an electron transport material in which R ^{11 to} R ¹⁷ each independently represents a hydrogen atom, a halogen atom, or an alkyl group, and R ¹⁸ represents an alkyl group or an aralkyl group having 3 to 12 carbon atoms. Is preferred.

  Hereinafter, although the exemplary compound of the electron transport material of Formula (1) is shown, it is not necessarily limited to this. In addition, the following exemplary compound numbers are described as an exemplary compound (1-number) below. Specifically, for example, Exemplified Compound 15 is represented below as “Exemplified Compound (1-15)”.

In addition, the abbreviations in the above exemplary compounds have the following meanings.
・ Ph: Phenyl group

Here, the electron transport material of Formula (1) may be used individually by 1 type, and may be used in combination of 2 or more type. Moreover, you may use together other electron transport materials other than the electron transport material of Formula (1) as needed in the range which does not inhibit the objective of this embodiment.
In addition, as content in the case of containing other electron transport material, 10 mass% or less is preferable with respect to the whole electron transport material.

  Examples of other electron transport materials include 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 electron transport materials may be used singly or in combination of two or more, but are not limited thereto.

The content of the electron transport material of the formula (1) with respect to the total solid content of the photosensitive layer is preferably 1.0% by mass or more and 3.5% by mass or less, preferably 2 from the viewpoint of reducing wear of the single-layer type photosensitive layer. It is 0.0 mass% or more and 3.0 mass% or less.
In addition, content of this electron transport material of Formula (1) is content of the whole of those electron transport materials, when two or more types of Formula (1) electron transport materials are used together.

-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, and 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 a surfactant, an antioxidant, a light stabilizer, and a heat stabilizer. Further, when the single-layer type photosensitive layer is a surface layer, it may contain fluororesin particles, silicone oil and the like.

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

  As a method for dispersing particles (for example, charge generation material) in the coating solution for forming a photosensitive layer, a media disperser such as a ball mill, a vibration ball mill, an attritor, a sand mill, a horizontal sand mill, a stirring, 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 5 μm to 50 μm, and still more preferably 10 μm to 40 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 body 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 one may be used in addition to the belt-like.

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

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

  In addition, the image forming apparatus 100 according to the present embodiment is not limited to the above-described configuration, and a well-known configuration, for example, a direct transfer type image forming apparatus that directly transfers a toner image formed on the electrophotographic photosensitive member 7 to a recording medium. It may be adopted.

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

<Example 1>
-Formation of photosensitive layer-
3 parts by mass of a hydroxygallium phthalocyanine pigment (CGM1) shown in Table 1 below as a charge generation material, 44 parts by mass of a bisphenol Z polycarbonate resin (viscosity average molecular weight 50,000: BD1) shown in Table 1 below as a binder resin, and electron transport 2 parts by mass of an electron transport material (ETM1) shown in Table 1 below as materials, 16 parts by mass of a hole transport material (HTM1) and 14 parts by mass of hole transport material (HTM2) shown in Table 1 below as a hole transport material, A mixture of 250 parts by mass of tetrahydrofuran as a solvent was dispersed in a sand mill for 4 hours using glass beads having a diameter of 1 mmφ to obtain a coating solution for forming a photosensitive layer.
The obtained photosensitive layer forming coating solution is applied on an aluminum substrate having a diameter of 30 mm, a length of 244.5 mm, and a thickness of 1 mm by a dip coating method, followed by drying and curing at a drying temperature of 140 ° C. and a drying time of 30 minutes. And a single-layer type photosensitive layer having a thickness of 30 μm was formed.
Through the above steps, an electrophotographic photosensitive member was produced.

<Examples 2 to 11 and Comparative Examples 1 to 10>
According to Table 1 and Table 2, the type and amount of the binder resin, the type and amount of the electron transport material, the type and amount of the hole transport material, and the drying conditions (drying temperature and drying time) for forming the photosensitive layer are changed. An electrophotographic photosensitive member was produced in the same manner as in Example 1 except that. However, in Comparative Examples 6 and 8, 10 parts by mass of m-terphenyl (1,3-diphenylbenzene: TF1) was further added to the coating solution.
In Tables 1 and 2, “-” indicates that no addition was made.

<Measurement / Evaluation>
The following measurements and evaluations were performed on the obtained electrophotographic photoreceptors. The results are shown in Tables 1 and 2.

[Measurement of glass transition temperature Tg of photosensitive layer before and after abrasion test]
For each electrophotographic photoreceptor obtained, the glass transition temperature Tg (A) of the photosensitive layer after the abrasion test and the glass transition temperature Tg (B) of the photosensitive layer before the abrasion test were measured according to the methods described above. ΔTg (= Tg (A) −Tg (B)) was calculated.

[Evaluation of sunspots]
The obtained photoreceptor was mounted on a modified HL5340D machine manufactured by Brother, and the following image quality was evaluated.
Using a modified HL5340D machine manufactured by Brother in an environment of a room temperature of 32 ° C. and a humidity of 85%, a 50% halftone image was printed on A4 size paper at 10 sheets / min and 2000 sheets / day. I started painting.
Thereafter, the operation was stopped overnight, and the black spots in the first blank image of the next morning were evaluated according to the following criteria.
-Evaluation criteria-
A: No black spots B: Black spots can be confirmed in the range of 1 to 5 but there is no problem in actual use C: Black spots in the range of 6 to 10 is confirmed, problems in actual use D: 11 or more black spots are confirmed, which causes a great problem in actual use

[Evaluation of wear]
Evaluation of wear was performed by using a modified HL5340D machine manufactured by Brother in an environment of room temperature 20 ° C and humidity 40%, and printing 12,000 50% halftone images on A4 size paper. It was evaluated with. The amount of wear was evaluated by the amount of wear per 1000 sheets (kpv) of paper.
A: Wear amount of 0.12 μm / kpv or less B: Wear amount of more than 0.12 μm / kpv and 0.15 μm / kpv or less C: Wear amount of more than 0.15 μm / kpv and 0.20 μm / kpv or less D: Wear The amount exceeds 0.20 μm / kpv

[Evaluation of sensitivity]
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 in an environment of 20 ° C. and 40% RH, the light of the tungsten lamp is emitted. 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 V0 (V) on the surface of the photoreceptor immediately after charging is set, and the half exposure amount E1 / 2 (μJ / cm ² ) at which the surface potential becomes 1/2 × VO (V) by light irradiation on the surface of the photoreceptor. It was measured. The evaluation criteria are as follows.
-Evaluation criteria-
A: Half exposure amount is 0.10 μJ / cm ² or more and 0.15 μJ / cm ² or less B: Half exposure amount is more than 0.15 μJ / cm ² and 0.175 μJ / cm ² or less C: Half exposure amount is 0.175 μJ / Cm ² and 0.20 μJ / cm ² or less D: Half exposure exceeds 0.20 μJ / cm ²

From the above results, it can be seen that the wear of this example is suppressed compared to the comparative example.
In addition, it can be seen that this example suppresses the generation of black spots and has high sensitivity.

  The details of the abbreviations in Tables 1 and 2 are as follows.

-Electron transport material-
ETM1: Exemplary compound (1-11) of an electron transport material represented by the general formula (1) [in the general formula (1), R ^{11 to} R ¹⁷ = H, R ¹⁸ = n-C ₄ H ₉ electrons Transport material]
ETM2: Exemplary compound (1-12) of an electron transport material represented by the general formula (1) [in the general formula (1), R ^{11 to} R ¹⁷ = H, R ¹⁸ = n-C ₁₁ H ₂₃ electrons Transport material]
ETM3: exemplary compound (1-19) of an electron transport material represented by the general formula (1) [in the general formula (1), R ^{11 to} R ¹⁷ = H, R ¹⁸ = −C ₆ H ₅ electron transport material]
ETM4: Electron transport material ETM4 represented by the following structural formula
ETM5: Electron transport material ETM5 represented by the following structural formula

—Hole Transport Material / HTM1: Exemplary Compound (2-1) of Hole Transport Material Represented by General Formula (2)
-HTM2: A hole transport material HTM2 represented by the following structural formula (corresponding to Exemplified Compound HT-4)

-Charge generation material-
CGM1 (ClGaPC): Chlorogallium phthalocyanine: Cukα Characteristic X-ray diffraction spectrum Bragg angle (2θ ± 0.2 °) using X-ray is at least 7.3 °, 16.0 °, 24.9 °, 28 V-type hydroxygallium phthalocyanine pigment having a diffraction peak at a position of 0 °

-Binder resin-
・ BD1: Bisphenol Z polycarbonate resin (viscosity average molecular weight 50,000)

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, 14 Lubricant, 40 Transfer device, 50 Intermediate transfer body, 100 Image forming apparatus, 120 Image forming apparatus, 131 Cleaning blade, 132 Fibrous member, 133 Fibrous member, 300 Process cartridge

Claims (4)

A conductive substrate;
A single-layer type photosensitive layer provided on the conductive substrate and including a binder resin, a charge generation material, a hole transport material, and an electron transport material represented by the following general formula (1);
Have
The glass transition temperature Tg (A) of the photosensitive layer after performing a wear test in which the photosensitive layer is worn by 2.0 μm while applying a voltage to the surface of the electrophotographic photosensitive member is the value before the wear test is performed. An electrophotographic photosensitive member that is 0.5 ° C. or more lower than the glass transition temperature Tg (B) of the photosensitive layer.

(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, R ¹⁸ represents an alkyl group, —L ¹⁹ —O—R ²⁰ , an aryl group, or an aralkyl group, provided that L ¹⁹ represents an alkylene group and R ²⁰ represents an alkyl group. The electrophotographic photosensitive member according to claim 1, wherein the hole transport material is a hole transport material represented by the following general formula (2).

(In General Formula (2), 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 p and q each independently represent 0 or 1.) The electrophotographic photosensitive member according to claim 1 or 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: