JP7275708B2 - Electrophotographic photoreceptor, process cartridge, and image forming apparatus - Google Patents

Description

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

Patent Document 1 discloses an electrophotographic photoreceptor provided with a photosensitive layer containing a hole transport agent, a charge generating agent and a binder resin on a substrate, wherein the hole transport agent is a specific hydrazone compound. Also disclosed is an electrophotographic photoreceptor characterized in that the value obtained by dividing the inorganic value in the binder resin by the organic value is 0.36 or more.

Patent Document 2 discloses a charge-transporting layer containing at least a hole-transporting material and a binder resin, and a charge-generating layer containing at least a charge-generating material, a hole-transporting material, an electron-transporting material and a binder resin, on a conductive support. In a laminated positively charged electrophotographic photoreceptor in which layers are sequentially laminated, the total amount of residual solvent contained in the charge generation layer and the charge transport layer is 50 μg/cm ² or less, and the charge generation The mass ratio of the electron transport material and the hole transport material in the layer is in the range of 5:1 to 4:2, the thickness of the charge transport layer is in the range of 3 μm to 40 μm, and the thickness of the charge generation layer is is in the range of 3 μm to 40 μm, and the total moisture content of the charge generation layer and the charge transport layer is in the range of 0.05% by mass to 1.5% by mass. A photoreceptor for a photoreceptor is disclosed.

Patent Document 3 discloses an electrophotographic photoreceptor having a photosensitive layer, wherein the photosensitive layer contains a hole transport agent and a binder resin, and the content of the hole transport agent is 100 parts by mass. 40 parts by mass or more and 100 parts by mass or less relative to the binder resin, the binder resin contains a resin having a specific repeating unit, and the hole transport agent contains a compound having a specific structure. , an electrophotographic photoreceptor is disclosed.

JP 2008-203766 A JP 2015-212837 A JP 2017-068014 A

In recent years, a photoreceptor having a single-layer type photosensitive layer (hereinafter also referred to as a "single-layer type photoreceptor") has been used as an electrophotographic photoreceptor from the viewpoint of manufacturing costs and the like. In the case of a single-layer type photoreceptor, it is desirable to use a homopolymer as the binder resin for the photoreceptor layer from the viewpoints of manufacturing cost and ease of surface regeneration (that is, refreshability).
However, in a single-layer photoreceptor using a homopolymer as the binder resin of the photosensitive layer, when oil (for example, finger oil) adheres to the surface of the single-layer photoreceptor, the oil causes Cracks may occur.

The present invention is caused by the oil adhering to the surface of the electrophotographic photoreceptor, compared to the case of having a single-layer photosensitive layer containing a resin that is a homopolymer and having a linear expansion coefficient α of greater than 0.0040. An object of the present invention is to provide an electrophotographic photoreceptor in which cracking of a photosensitive layer is suppressed.

The above problems are solved by the following means.

<1>
a conductive substrate;
A single-layer type photosensitive layer provided on the conductive substrate and containing a resin that is a homopolymer, a charge generating material, a hole transporting material, and an electron transporting material, wherein the glass transition temperature of the photosensitive layer is Tg a single-layer photosensitive layer having an in-plane linear expansion coefficient α of 0.0040 or less at (Tg+10)° C. or higher and (Tg+30)° C. or lower, where °C;
an electrophotographic photoreceptor.
<2>
The electrophotographic photoreceptor according to <1>, wherein the linear expansion coefficient α is 0.0025 or more.

<3>
The electrophotographic photoreceptor according to <1> or <2>, wherein the homopolymer resin contains at least one selected from a polycarbonate resin and a polyarylate resin.
<4>
The electrophotographic photoreceptor according to <3>, wherein the homopolymer resin contains at least a polycarbonate resin.
<5>
The electrophotographic photoreceptor according to <4>, wherein the polycarbonate resin has a repeating unit represented by the following general formula (1).

In general formula (1), R ¹ and R ² each independently represent a hydrogen atom, a substituted or unsubstituted alkyl group having 5 or less carbon atoms, or a substituted or unsubstituted phenyl group, and R ¹ and R ² may form a cyclo ring. R ³ and R ⁴ each independently represent a hydrogen atom or a substituted or unsubstituted alkyl group having 3 or less carbon atoms.

<6>
The electrophotographic photoreceptor according to any one of <1> to <5>, wherein the content of the resin that is the homopolymer is 40% by mass or more and 60% by mass or less with respect to the entire photosensitive layer.
<7>
The electrophotographic photoreceptor according to <6>, wherein the content of the resin that is the homopolymer is 50% by mass or more and 60% by mass or less with respect to the entire photosensitive layer.
<8>
the charge generating material comprises a V-type hydroxygallium phthalocyanine pigment;
The hole transport material contains a compound represented by the following general formula (B-1),
The electrophotographic photoreceptor according to any one of <1> to <7>, wherein the electron transport material contains a compound represented by the following general formula (C-1).

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 ), and R ^B3 to R ^B7 each independently represent a hydrogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aryl group.

In general formula (C-1), R ^C11 , R ^C12 , R ^C13 and R ^C14 each independently represent a hydrogen atom, an alkyl group, an alkoxy group, a halogen atom or a phenyl group.

<9>
The electrophotographic photoreceptor according to any one of <1> to <8>,
A process cartridge that can be attached to and detached from an image forming apparatus.
<10>
the electrophotographic photoreceptor according to any one of <1> to <8>;
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 an electrostatic latent image formed on the surface of the electrophotographic photosensitive member with a developer containing toner to form a toner image;
a transfer means for transferring the toner image onto the surface of a recording medium;
An image forming apparatus comprising:

According to the invention according to <1> or <8>, compared to the case of having a single-layer type photosensitive layer containing a resin that is a homopolymer and having a coefficient of linear expansion α greater than 0.0040, electrophotographic photosensitive Provided is an electrophotographic photoreceptor in which the occurrence of cracks in the photosensitive layer due to oil adhering to the surface of the body is suppressed.
According to the invention relating to <2>, there is provided an electrophotographic photoreceptor in which the occurrence of cracks in the photosensitive layer under low temperature and low humidity conditions is suppressed compared to when the linear expansion coefficient α is less than 0.0025. .

According to the invention according to <3>, even when the resin that is a homopolymer contains at least one selected from polycarbonate resins and polyarylate resins, the linear expansion coefficient α is greater than 0.0040. Provided is an electrophotographic photoreceptor in which cracking of the photosensitive layer caused by oil adhering to the surface of the electrophotographic photoreceptor is suppressed as compared with the case of having a layered photosensitive layer.
According to the invention according to <4>, even when the resin that is a homopolymer contains a polycarbonate resin, compared with the case where the linear expansion coefficient α is greater than 0.0040, it has a single-layer type photosensitive layer. Accordingly, an electrophotographic photoreceptor is provided in which the occurrence of cracks in the photosensitive layer due to oil adhering to the surface of the electrophotographic photoreceptor is suppressed.
According to the invention according to <5>, even when the polycarbonate resin, which is a homopolymer, has a repeating unit represented by the general formula (1), the linear expansion coefficient α is greater than 0.0040 Single layer Provided is an electrophotographic photoreceptor in which the occurrence of cracks in the photosensitive layer due to oil adhering to the surface of the electrophotographic photoreceptor is suppressed as compared with the case of having a photosensitive layer of a mold.

According to the invention according to <6>, even if the content of the resin that is a homopolymer is 40% by mass or more and 60% by mass or less, the linear expansion coefficient α including the resin that is a homopolymer is 0.0040 Provided is an electrophotographic photoreceptor in which cracking of the photosensitive layer due to oil adhering to the surface of the electrophotographic photoreceptor is suppressed as compared with the case of having a larger single-layer type photosensitive layer.
According to the invention according to <7>, even if the content of the resin that is a homopolymer is 50% by mass or more and 60% by mass or less, the linear expansion coefficient α is 0.0040 including the resin that is a homopolymer. Provided is an electrophotographic photoreceptor in which cracking of the photosensitive layer due to oil adhering to the surface of the electrophotographic photoreceptor is suppressed as compared with the case of having a larger single-layer type photosensitive layer.

According to the invention according to <9> or <10>, compared to the case of providing an electrophotographic photoreceptor having a single-layer type photosensitive layer containing a resin that is a homopolymer and having a linear expansion coefficient α of greater than 0.0040 As a result, a process cartridge or an image forming apparatus is provided in which image defects due to cracking of the photosensitive layer caused by oil adhering to the surface of the electrophotographic photosensitive member are suppressed.

1 is a schematic partial cross-sectional view showing an example of the layer structure of an electrophotographic photoreceptor according to the exemplary embodiment; FIG. 1 is a schematic configuration diagram showing an example of an image forming apparatus according to an embodiment; FIG. FIG. 2 is a schematic configuration diagram showing another example of the image forming apparatus according to the embodiment;

An embodiment that is an example of the present invention will be described below. These descriptions and examples are illustrative of embodiments and do not limit the scope of the invention.

[Electrophotographic photoreceptor]
An electrophotographic photoreceptor (hereinafter also referred to as "photoreceptor") according to the present embodiment comprises a conductive substrate, a homopolymer resin provided on the conductive substrate, a charge-generating material, and a hole-transporting material. A single-layer type photosensitive layer containing an electron transport material, wherein when the glass transition temperature of the photosensitive layer is Tg ° C., the in-plane linear expansion coefficient and a single-layer type photosensitive layer having a value of 0.0040 or less.

2. Description of the Related Art In recent years, a single-layer type photoreceptor having a single-layer type photosensitive layer has been used as a photoreceptor from the viewpoint of manufacturing cost and the like. Among the single-layer type photoreceptors, a homopolymer is preferably used as the binder resin for the photosensitive layer from the viewpoint of further suppressing the manufacturing cost. In particular, in a single-layer type photoreceptor in which a single-layer type photosensitive layer using a homopolymer as a binder resin is the outermost layer, compared to the case of using a copolymer, the surface regeneration by a cleaning blade or a developing roller is difficult. is easy, and good refreshability is likely to be obtained.

However, in a single-layer type photoreceptor using a homopolymer as a binder resin for the photosensitive layer, if oil (for example, finger oil) adheres to the surface of the single-layer type photoreceptor, the oil will spread inside the photosensitive layer. and cracks (hereinafter also referred to as “chemical cracks”) may occur due to the permeated oil.
Although the reason why the chemical cracks occur is not clear, it is believed that stress remains in the photosensitive layer. The photosensitive layer can be obtained, for example, by applying a photosensitive layer-forming coating liquid to a substrate and drying it. In the process of cooling after drying (for example, the process of returning the temperature of the photoreceptor, which has been raised by drying, to room temperature (e.g., 20° C.)), the cooling rate and cooling between the conductive substrate and the photosensitive layer It is believed that a difference in shrinkage occurs, and stress remains in the photosensitive layer due to this difference. When oil adheres to the photosensitive layer with residual stress and permeates into the photosensitive layer, the components in the photosensitive layer gradually dissolve into the oil, creating voids and leaving the entangled structure of the molecular chains in the binder resin. It is presumed that the stress cannot be endured and chemical cracks tend to occur.

In particular, when a homopolymer is used as the binder resin for the photosensitive layer, chemical cracks are more likely to occur than when a copolymer is used as the binder resin for the photosensitive layer. The reason for this is not clear, but in a copolymer, the stress is easily relieved by the mutual interaction of different structural units, whereas in a homopolymer, the stress is easily maintained because it does not have different structural units. , it is presumed that chemical cracks are likely to occur.

In contrast, in the present embodiment, the linear expansion coefficient α of the photosensitive layer is 0.0040 or less. A photosensitive layer having a coefficient of linear expansion α of 0.0040 or less has a smaller residual stress released when the photosensitive layer is heated to a glass transition temperature or higher than a photosensitive layer having a coefficient of linear expansion α of more than 0.0040. That is, a photosensitive layer having a coefficient of linear expansion α of 0.0040 or less has a small amount of stress remaining in the photosensitive layer. presumed to be suppressed.
By applying the photoreceptor of the present embodiment, in which chemical cracks are suppressed, to an image forming apparatus, an image in which image defects caused by chemical cracks are suppressed can be obtained.

Here, the "linear expansion coefficient α" is a value obtained by the following measurement.
First, a measurement sample having a sample cross-sectional area of 0.155 mm ² and a sample length of 5.0 mm is cut out from the photosensitive layer to be measured. The measurement sample is cut so that the sample length direction is the in-plane direction of the photosensitive layer (that is, the direction perpendicular to the thickness direction of the photosensitive layer).
On the other hand, a thermomechanical analyzer (Shimazu Co., model number: TMA-60/60H) is used as a measuring device, the load of the measuring device is 2.0 g, the measurement temperature range is 25 ° C. or higher and 150 ° C. or lower, and the heating rate is 5 ° C./ Set to min, and measure the temperature dependence of the sample length in the measurement sample.
When the glass transition temperature of the measurement sample is Tg, the sample length is _L0 , the amount of change in the sample length in the range of (Tg + 10) ° C. or higher and (Tg + 30) ° C. is ΔL, and the amount of temperature change is ΔT, the following formula is obtained. A coefficient of linear expansion α is calculated.
Formula: α = (1/L ₀ ) x (ΔL/ΔT)

The means for controlling the value of the "linear expansion coefficient α" within the above range is not particularly limited. After that, the set temperature of the control room is lowered in multiple stages, and the temperature is gradually cooled to room temperature (eg, 20° C.), thereby controlling the value of the coefficient of linear expansion α.

Hereinafter, the electrophotographic photoreceptor according to this embodiment will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals, and redundant explanations are omitted.
FIG. 1 schematically shows a partial cross section of an electrophotographic photoreceptor 7 according to this embodiment. The electrophotographic photoreceptor 7 shown in FIG. 1 includes, for example, a conductive substrate 3, and an undercoat layer 1 and a monolayer type photosensitive layer 2 provided on the conductive substrate 3 in this order.
In addition, the undercoat layer 1 is a layer provided as needed. 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 .

The electrophotographic photoreceptor shown in FIG. 1 may be further provided with other layers as necessary. Other layers include, for example, an intermediate layer provided between the undercoat layer and the photosensitive layer, and a protective layer provided on the single-layer type photosensitive layer.
From the viewpoint of manufacturing cost, it is preferable that the single-layer type photosensitive layer is the outermost layer (that is, the surface layer). When the single-layer type photosensitive layer is the outermost layer, oil adhering to the surface of the photoreceptor easily permeates into the photosensitive layer. Chemical cracks are suppressed even if the single layer type photosensitive layer is the outermost layer.

Each layer of the electrophotographic photoreceptor according to the exemplary embodiment will be described in detail below. In addition, the code|symbol is abbreviate|omitted and demonstrated.

(Conductive substrate)
Examples of conductive substrates include metal plates, metal drums, and metal belts containing metals (aluminum, copper, zinc, chromium, nickel, molybdenum, vanadium, indium, gold, platinum, etc.) or alloys (stainless steel, etc.). is mentioned. Examples of conductive substrates include paper, resin films, belts, etc., coated, vapor-deposited, or laminated with conductive compounds (e.g., conductive polymers, indium oxide, etc.), metals (e.g., aluminum, palladium, gold, etc.) or alloys. is also mentioned. Here, "conductivity" means having a volume resistivity of less than 10 ¹³ Ωcm.

When the electrophotographic photoreceptor 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. It is preferable that the surface is roughened to the following. When non-interfering light is used as the light source, roughening is not particularly necessary to prevent interference fringes, but it is suitable for longer life because it suppresses the occurrence of defects due to irregularities on the surface of the conductive substrate.

Surface roughening methods include, for example, wet honing in which an abrasive is suspended in water and sprayed onto the support, centerless grinding in which a conductive substrate is pressed against a rotating grindstone and continuously ground. Examples include anodizing treatment and the like.

As a roughening method, conductive or semiconductive powder is dispersed in a resin to form a layer on the surface of the conductive substrate without roughening the surface of the conductive substrate. A method of roughening with particles dispersed in a layer is also included.

In the surface roughening treatment by anodization, an oxide film is formed on the surface of a conductive substrate by anodizing a metal (eg, aluminum) conductive substrate as an anode in an electrolyte solution. Examples of electrolyte solutions include sulfuric acid solutions and oxalic acid solutions. However, the porous anodic oxide film formed by anodic oxidation is chemically active as it is, is easily contaminated, and has large resistance fluctuations depending on the environment. Therefore, the micropores of the porous anodized film are filled with pressurized steam or boiling water (a metal salt such as nickel may be added) by volume expansion due to the hydration reaction, thereby achieving more stable hydration and oxidation. It is preferable to perform a pore-sealing treatment that transforms into a product.

The film thickness of the anodized film is preferably 0.3 μm or more and 15 μm or less, for example. When this film thickness is within the above range, there is a tendency for the film to exhibit barrier properties against injection, 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 treated with boehmite.
The treatment with an acidic treatment liquid is performed, for example, as follows. 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, phosphoric acid in the range of 10% by mass to 11% by mass, chromic acid in the range of 3% by mass to 5% by mass, and hydrofluoric acid in the range of 3% by mass to 5% by mass. It is preferable that the total concentration of these acids is in the range of 0.5 mass % or more and 2 mass % or less, and the range of 13.5 mass % or more and 18 mass % or less. The treatment temperature is preferably 42° C. or higher and 48° C. or lower, for example. The film thickness of the coating is preferably 0.3 μm or more and 15 μm or less.

The boehmite treatment is performed, for example, by immersing the substrate in pure water at a temperature of 90° C. or higher and 100° C. or lower for 5 to 60 minutes, or by contacting the substrate with heated steam at a temperature of 90° C. or higher and 120° C. or lower for 5 to 60 minutes. The film thickness of the coating is preferably 0.1 μm or more and 5 μm or less. This may be further anodized using an electrolytic 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 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, metal oxide particles such as tin oxide particles, titanium oxide particles, zinc oxide particles, and zirconium oxide particles are preferable as the inorganic particles having the above resistance value, 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, 50 nm or more and 2000 nm or less (preferably 60 nm or more and 1000 nm or less).

The content of the inorganic particles is, for example, preferably 10% by mass or more and 80% by mass or less, more preferably 40% by mass or more and 80% by mass or less, relative to the binder resin.

The inorganic particles may be surface-treated. Two or more kinds of inorganic particles having different surface treatments or different particle diameters may be mixed and used.

Examples of surface treatment agents include silane coupling agents, titanate-based coupling agents, aluminum-based coupling agents, and surfactants. In particular, a silane coupling agent is preferred, and a silane coupling agent having an amino group is more preferred.

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

You may use a silane coupling agent in mixture of 2 or more types. 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, etc., but are not limited thereto. not a thing

The surface treatment method using the surface treatment agent may be any 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 preferably contains an electron-accepting compound (acceptor compound) together with the inorganic particles from the viewpoint of enhancing the long-term stability of electrical properties and the carrier-blocking property.

Examples of electron-accepting compounds include quinone compounds such as chloranil and bromoanil; tetracyanoquinodimethane compounds; 2,4,7-trinitrofluorenone, 2,4,5,7-tetranitro-9-fluorenone, and the like. fluorenone compounds; 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;
A compound having an anthraquinone structure is particularly preferable as the electron-accepting compound. As the compound having an anthraquinone structure, for example, hydroxyanthraquinone compounds, aminoanthraquinone compounds, aminohydroxyanthraquinone compounds, etc. are preferable, and specifically, for example, anthraquinone, alizarin, quinizarin, anthrafin, purpurin, etc. are preferable.

The electron-accepting compound may be dispersed in the undercoat layer together with the inorganic particles, or may be attached to the surfaces of the inorganic particles.

Examples of the method of adhering 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, an electron-accepting compound dissolved in an organic solvent is added dropwise while stirring inorganic particles with a mixer having a large shearing force, and the electron-accepting compound is sprayed with dry air or nitrogen gas. It is a method of adhering to the surface of inorganic particles. Dropping or spraying of the electron-accepting compound is preferably carried out at a temperature not higher than the boiling point of the solvent. After dropping or spraying the electron-accepting compound, baking may be further performed at 100° C. or higher. Baking is not particularly limited as long as the temperature and time are such that electrophotographic properties can be obtained.

In the wet method, for example, by stirring, ultrasonic waves, sand mill, attritor, ball mill, etc., while inorganic particles are dispersed in a solvent, an electron-accepting compound is added, stirred or dispersed, and then the solvent is removed to obtain electrons. This is a method of adhering a receptive compound to the surface of inorganic particles. Solvent removal methods include distilling off by filtration or distillation. After removing the solvent, baking may be further performed at 100° C. or higher. Baking is not particularly limited as long as the temperature and time allow electrophotographic properties to be obtained. In the wet method, the water contained in the inorganic particles may be removed before adding the electron-accepting compound, examples of which include a method of removing while stirring and heating in a solvent, and a method of removing by azeotroping with a solvent. mentioned.

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

The content of the electron-accepting compound is, for example, 0.01% by mass or more and 20% by mass or less, preferably 0.01% by mass or more and 10% by mass or less, relative to the inorganic particles.

Examples of binder resins used in the undercoat layer include acetal resins (for example, polyvinyl butyral), polyvinyl alcohol resins, polyvinyl acetal resins, casein resins, polyamide resins, cellulose resins, gelatin, polyurethane resins, polyester resins, and unsaturated polyesters. Resins, methacrylic resins, acrylic resins, polyvinyl chloride resins, polyvinyl acetate resins, vinyl chloride-vinyl acetate-maleic anhydride resins, silicone resins, silicone-alkyd resins, urea resins, phenolic resins, phenol-formaldehyde resins, melamine resins, Urethane resins, alkyd resins, known polymer compounds such as epoxy resins; zirconium chelate compounds; titanium chelate compounds; aluminum chelate compounds; titanium alkoxide compounds;
Examples of the binder resin used in the undercoat layer include charge-transporting resins having a charge-transporting group, conductive resins (eg, polyaniline, etc.), and the like.

Among these, resins that are insoluble in the coating solvent of the upper layer are suitable as the binder resin used in the undercoat layer. 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 a curing agent are preferred.
When two or more of these binder resins are used in combination, the mixing ratio is set according to need.

The undercoat layer may contain various additives for improving electrical properties, environmental stability, and image quality.
Examples of the additive include known materials such as electron-transporting pigments such as polycyclic condensed and azo-based pigments, zirconium chelate compounds, titanium chelate compounds, aluminum chelate compounds, titanium alkoxide compounds, organic titanium compounds, and silane coupling agents. be done. The silane coupling agent is used for the surface treatment of the inorganic particles as described above, and may be added to the undercoat layer as an additive.

Silane coupling agents as additives include, for example, 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-aminopropylmethyldimethoxysilane, N,N-bis(2-hydroxyethyl)-3-aminopropyltriethoxysilane, 3-chloropropyltrimethoxysilane and the like.

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

Examples of titanium chelate compounds include tetraisopropyl titanate, tetra-normal 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 triethanolamine, polyhydroxytitanium stearate, and the like.

Examples of aluminum chelate compounds include aluminum isopropylate, monobutoxyaluminum diisopropylate, aluminum butyrate, diethylacetoacetate aluminum diisopropylate, and aluminum tris(ethylacetoacetate).

These additives may be used alone or as mixtures or polycondensates of multiple compounds.

The undercoat layer preferably has a Vickers hardness of 35 or higher.
The surface roughness (ten-point average roughness) of the undercoat layer is 1/(4n) (n is the refractive index of the upper layer) to 1/2 of the exposure laser wavelength λ used to suppress moiré images. should be adjusted to
Resin particles or the like may be added to the undercoat layer to adjust the surface roughness. Examples of resin particles include silicone resin particles and crosslinked polymethyl methacrylate resin particles. Further, the surface of the undercoat layer may be polished to adjust the surface roughness. Polishing methods include buffing, sandblasting, wet honing, and grinding.

Formation of the undercoat layer is not particularly limited, and a well-known formation method is used. and, if necessary, by heating.

Solvents for preparing the undercoat layer-forming coating liquid include known organic solvents such as alcohol solvents, aromatic hydrocarbon solvents, halogenated hydrocarbon solvents, ketone solvents, ketone alcohol solvents, ether solvents, Solvents, ester solvents and the like can be mentioned.
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, Ordinary organic solvents such as n-butyl acetate, dioxane, tetrahydrofuran, methylene chloride, chloroform, chlorobenzene and toluene can be used.

Examples of the method for dispersing the inorganic particles when preparing the undercoat layer-forming coating solution include known methods such as a roll mill, ball mill, vibrating ball mill, attritor, sand mill, colloid mill, and paint shaker.

Examples of methods for applying the undercoat layer-forming coating liquid onto the conductive substrate include blade coating, wire bar coating, spray coating, dip coating, bead coating, air knife coating, and curtain coating. Ordinary methods such as

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

(middle layer)
Although not shown, an intermediate layer may be further provided between the undercoat layer and the photosensitive layer.
The intermediate layer is, for example, a layer containing resin. Examples of resins used for the intermediate layer include acetal resins (for example, polyvinyl butyral), polyvinyl alcohol resins, polyvinyl acetal resins, casein resins, polyamide resins, cellulose resins, gelatin, polyurethane resins, polyester resins, methacrylic resins, acrylic resins, Polyvinyl chloride resins, polyvinyl acetate resins, vinyl chloride-vinyl acetate-maleic anhydride resins, silicone resins, silicone-alkyd resins, phenol-formaldehyde resins, melamine resins and other high-molecular compounds can be mentioned.
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.
These compounds used for the intermediate layer may be used singly 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 zirconium atoms or silicon atoms.

Formation of the intermediate layer is not particularly limited, and a well-known forming method is used. It is done by heating according to.
As a coating method for forming the intermediate layer, a usual method such as a dip coating method, a thrust coating method, a wire bar coating method, a spray coating method, a blade coating method, a knife coating method and a curtain coating method can be used.

The film thickness of the intermediate layer is preferably set in the range of 0.1 μm or more and 3 μm or less, for example. Note that the intermediate layer may be used as an undercoat layer.

(Single-layer photosensitive layer)
The single-layer type photosensitive layer in this embodiment contains a resin that is a homopolymer, a charge generation material, a hole transport material, and an electron transport material, and has a linear expansion coefficient α of 0.0040 or less.
First, each component contained in the single-layer type photosensitive layer will be described.

- Binder resin -
A single layer type photosensitive layer contains a homopolymer as a binder resin.
Examples of homopolymers include polycarbonate resins (homopolymers such as bisphenol A, bisphenol Z, bisphenol C, and bisphenol TP), polyester resins, polyarylate resins, methacrylic resins, acrylic resins, polyvinyl chloride resins, polyvinyl chloride resins, and the like. vinylidene resin, polystyrene resin, polyvinyl acetate resin, silicone resin, poly-N-vinylcarbazole, polysilane, and the like. These homopolymers may be used singly or in combination of two or more. In the present embodiment, even if only one type of homopolymer is used as the binder resin, chemical cracks are suppressed because the coefficient of linear expansion α is within the above range.

Among these, the homopolymer preferably contains at least one selected from polycarbonate resins and polyarylate resins from the viewpoint of the mechanical strength of the photosensitive layer.
When the homopolymer contains at least one selected from a polycarbonate resin and a polyarylate resin, the total content of the polycarbonate resin and the polyarylate resin with respect to the entire homopolymer is preferably 90% by mass or more, preferably 95% by mass. It is more preferably 98% by mass or more, and more preferably 98% by mass or more.

Further, the homopolymer more preferably contains a polycarbonate resin from the viewpoint of production cost and image quality stability (for example, improvement of color spot resistance by facilitating removal of paper dust adhered to the photoreceptor). In the present embodiment, even if the homopolymer used as the binder resin contains a polycarbonate resin, chemical cracks are suppressed because the linear expansion coefficient α is within the above range.
When the homopolymer contains a polycarbonate resin, the content of the polycarbonate resin with respect to the entire homopolymer is preferably 90% by mass or more, more preferably 95% by mass or more, and preferably 98% by mass or more. More preferred.

The polycarbonate resin contained in the homopolymer preferably has a repeating unit represented by the following general formula (1) in terms of mechanical strength.

In general formula (1), R ¹ and R ² each independently represent a hydrogen atom, a substituted or unsubstituted alkyl group having 5 or less carbon atoms, or a substituted or unsubstituted phenyl group, and R ¹ and R ² may form a cyclo ring. R ³ and R ⁴ each independently represent a hydrogen atom or a substituted or unsubstituted alkyl group having 3 or less carbon atoms.

In general formula (1), the alkyl groups having 5 or less carbon atoms represented by R ¹ and R ² each independently include a linear or branched alkyl group, such as methyl group, ethyl group, n-propyl group, n-butyl group, n-pentyl group, isopropyl group, isobutyl group, sec-butyl group, tert-butyl group, isopentyl group, neopentyl group, tert-pentyl group.

In general formula (1), examples of substituents further possessed by the alkyl group or phenyl group having 5 or less carbon atoms represented by R ¹ and R ² include halogen atoms (e.g., fluorine atom, chlorine atom), alkyl groups (e.g., carbon an alkyl group having a number of 1 to 6), a cycloalkyl group (e.g., a cycloalkyl group having 5 to 7 carbon atoms), an alkoxy group (e.g., an alkoxy group having 1 to 4 carbon atoms), an aryl group (e.g., a phenyl group, naphthyl group, biphenylyl group, etc.).

In the general formula (1), a cyclo ring formed by R ¹ and R ² (that is, a group represented by R ¹ , a group represented by R ² , and a carbon atom to which R ¹ and R ² are directly bonded) The cyclo ring that is used) includes, for example, a substituted or unsubstituted cycloalkylene group. The substituents further possessed by the cycloalkylene group include the same substituents further possessed by the alkyl group having 5 or less carbon atoms or the phenyl group represented by R ¹ and R ² in the general formula (1).
The number of carbon atoms in the cycloalkylene group (however, in the case of a substituted cycloalkylene group, excluding the number of carbon atoms in the further substituents) is preferably 3 or more and 12 or less, more preferably 3 or more and 10 or less, and even more preferably 5 or more and 8 or less. . Specific examples of the cycloalkylene group include a cyclopropylene group, a cyclopentylene group, a cyclohexylene group, a cyclooctylene group, a cyclododecanylene group and the like. Among these, a cyclohexylene group is preferable as the cycloalkylene group.

R ¹ and R ² in general formula (1) are each independently a hydrogen atom, an unsubstituted alkyl group having 5 or less carbon atoms, an unsubstituted phenyl group, and an unsubstituted group formed by R ¹ and R ² is preferred, an unsubstituted methyl group, an unsubstituted phenyl group, an unsubstituted cyclohexylene group formed by R ¹ and R ² is more preferred, and an unsubstituted cyclohexylene group formed by R ¹ and R ² is more preferred. Substituted cyclohexylene groups are more preferred.

In the general formula (1), the alkyl group having 3 or less carbon atoms represented by R ³ and R ⁴ is the alkyl group having 5 or less carbon atoms represented by R ¹ and R ² in the general formula (1) and having 3 or less carbon atoms. The same thing as the thing of is mentioned.
In general formula (1), the substituent further included in the alkyl group having 3 or less carbon atoms represented by R ³ and R ⁴ is the alkyl group having 5 or less carbon atoms represented by R ¹ and R ² in general formula (1). The same substituents as the substituent further possessed by the group or the phenyl group can be mentioned.

R ³ and R ⁴ in general formula (1) are each independently preferably a hydrogen atom or an unsubstituted alkyl group having 3 or less carbon atoms, more preferably a hydrogen atom or an unsubstituted methyl group, and R ¹ and R A cyclohexylene group formed with ² is more preferred.

Specific examples of the repeating unit represented by general formula (1) include repeating units represented by structural formulas (1-1) to (1-5) below.

When the binder resin contains a resin other than a homopolymer, the ratio of the homopolymer to the entire binder resin is preferably 90% by mass or more, more preferably 95% by mass or more, and more preferably 98% by mass. It is more preferable that it is above.

The viscosity-average molecular weight of the binder resin is preferably 50,000 or less, preferably 45,000 or less, from the viewpoint of image quality stability (for example, improvement of color spot resistance by facilitating removal of paper dust adhered to the photoreceptor). It is more preferably 40,000 or less. Moreover, the viscosity-average molecular weight of the homopolymer is preferably 20,000 or more from the viewpoint of mechanical strength.

Here, the following one-point measurement method is used to measure the viscosity-average molecular weight of the binder resin.
First, the photosensitive layer to be measured is exposed from the photosensitive member. Then, a part of the photosensitive layer is cut out to prepare a sample for measurement.
Next, the binder resin is extracted from the measurement sample. 1 g of the extracted binder resin is dissolved in 100 cm ³ of methylene chloride, and the specific viscosity ηsp is measured with an Ubbelohde viscometer under a measurement environment of 25°C. Then, the relational expression ηsp/c=[η]+0.45[η] ² c (where c is the concentration (g/cm ³ ), the intrinsic viscosity [η] (cm ³ /g) is obtained, and H. Schnell The viscosity average molecular weight Mv is obtained from the given formula [η]=1.23×10 ⁻⁴ Mv ^0.83 .

The content of the resin, which is a homopolymer, relative to the entire photosensitive layer is, for example, in the range of 35% by mass to 60% by mass, preferably 40% by mass to 60% by mass, and 50% by mass to 60% by mass. A range of mass % or less is more preferable. If the content of the homopolymer resin relative to the entire photosensitive layer is large, chemical cracks are likely to occur in general. However, if the linear expansion coefficient α is within the above range, chemical cracks are suppressed.

-Charge generation material-
Examples of charge-generating materials include azo pigments such as bisazo and trisazo; condensed aromatic pigments such as dibromoanthanthrone; perylene pigments; pyrrolopyrrole pigments;

Among these, a metal phthalocyanine pigment or a metal-free phthalocyanine pigment is preferably used as the charge generation material in order to cope with laser exposure in the near-infrared region. Specific examples include hydroxygallium phthalocyanine; chlorogallium phthalocyanine; dichlorotin phthalocyanine; and titanyl phthalocyanine.

On the other hand, in order to correspond to laser exposure in the near-ultraviolet region, charge generation materials include condensed aromatic pigments such as dibromoanthanthrone; thioindigo pigments; porphyrazine compounds; zinc oxide; trigonal selenium; etc. should be used.

That is, as the charge-generating material, for example, when a light source with an exposure wavelength of 380 nm or more and 500 nm or less is used, an inorganic pigment is preferably used. A phthalocyanine pigment is preferably used.

Above all, it is desirable to use at least one selected from hydroxygallium phthalocyanine pigments and chlorogallium phthalocyanine pigments as the charge generation material. These charge generation materials may be used alone or in combination of two or more. A hydroxygallium phthalocyanine pigment is preferable from the viewpoint of increasing the sensitivity of the photoreceptor.
When the hydroxygallium phthalocyanine pigment and the chlorogallium phthalocyanine pigment are used together, the ratio of the hydroxygallium phthalocyanine pigment and the chlorogallium phthalocyanine pigment is, in mass ratio, hydroxygallium phthalocyanine pigment:chlorogallium phthalocyanine pigment=9:1 or more. A ratio of 3:7 (preferably 9:1 to 6:4) is preferred.

The hydroxygallium phthalocyanine pigment is not particularly limited, but a V-type hydroxygallium phthalocyanine pigment is preferable from the viewpoint of improving the sensitivity of the photoreceptor.
In particular, as the hydroxygallium phthalocyanine pigment, for example, a hydroxygallium phthalocyanine pigment having a maximum peak wavelength in the range of 810 nm or more and 839 nm or less in the spectral absorption spectrum in the wavelength range of 600 nm or more and 900 nm or less can provide better dispersibility. desirable from this point of view.

The hydroxygallium phthalocyanine pigment having a maximum peak wavelength in the range of 810 nm or more and 839 nm or less preferably has an average particle size within a specific range and a BET specific surface area within a specific range. Specifically, the average particle diameter is preferably 0.20 μm or less, more preferably 0.01 μm or more and 0.15 μm or less. On the other hand, the BET specific surface area is preferably 45 m ² /g or more, more preferably 50 m ² /g or more, and even more preferably 55 m ² /g or more and 120 m ² /g or less. The average particle diameter is a volume average particle diameter, and is a value measured by a laser diffraction scattering type particle size distribution analyzer (Horiba LA-700). The BET specific surface area is a value measured by a nitrogen substitution method using a fluid type specific surface area automatic measuring device (Shimadzu Corporation Flow Soap II2300).

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

The hydroxygallium phthalocyanine pigment preferably has an average particle size of 0.2 μm or less, a maximum particle size of 1.2 μm or less, and a BET specific surface area of 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°, and 28.0° in an X-ray diffraction spectrum using CuKα characteristic X-rays. It is preferably V-type having a diffraction peak at .

On the other hand, the chlorogallium phthalocyanine pigment has diffraction peaks at Bragg angles (2θ±0.2°) of 7.4°, 16.6°, 25.5° and 28.3° from the viewpoint of the sensitivity of the photosensitive layer. Preferred are compounds having The preferred ranges of the maximum peak wavelength, average particle size, maximum particle size, and BET specific surface area of the chlorogallium phthalocyanine pigment are the same as those of the hydroxygallium phthalocyanine pigment.

The charge generation material may be used singly or in combination of two or more.

The content of the charge-generating material relative to the total solid content of the single-layer type photosensitive layer is preferably 0.5% by mass or more and 5% by mass or less, preferably 1% by mass or more and 5% by mass or less, and 1.2% by mass or more4 0.5% by mass or less is more preferable.

-Hole transport material-
The hole transport material is not particularly limited, but examples include oxadiazole derivatives such as 2,5-bis(p-diethylaminophenyl)-1,3,4-oxadiazole; pyrazoline derivatives such as phenyl-pyrazoline, 1-[pyridyl-(2)]-3-(p-diethylaminostyryl)-5-(p-diethylaminostyryl)pyrazoline; triphenylamine, N,N'-bis(3, Aromatic tertiary amino compounds such as 4-dimethylphenyl)biphenyl-4-amine, tri(p-methylphenyl)aminyl-4-amine, dibenzylaniline; N,N'-bis(3-methylphenyl)- Aromatic tertiary diamino compounds such as N,N'-diphenylbenzidine, 3-(4'-dimethylaminophenyl)-5,6-di-(4'-methoxyphenyl)-1,2,4-triazine, etc. hydrazone derivatives such as 4-diethylaminobenzaldehyde-1,1-diphenylhydrazone; quinazoline derivatives such as 2-phenyl-4-styryl-quinazoline; 6-hydroxy-2,3-di( benzofuran derivatives such as p-methoxyphenyl)benzofuran; α-stilbene derivatives such as p-(2,2-diphenylvinyl)-N,N-diphenylaniline; enamine derivatives; carbazole derivatives such as N-ethylcarbazole; -vinylcarbazole and derivatives thereof, etc.; polymers having groups composed of the above compounds in the main chain or side chain; and the like. These hole transport materials may be used singly or in combination of two or more.
Specific examples of the hole transport material include compounds represented by the following general formula (B-1) and compounds represented by the following general formula (B-2). Among them, the compound represented by the following general formula (B-1) is preferable as the hole transport material from the viewpoint of improving the sensitivity of the photoreceptor.

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 ), and 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 substituents include 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 ^{3 B8} and R ^{3 B8'} may be the same or different, and each independently a hydrogen atom, a halogen atom, an alkyl group having 1 to 5 carbon atoms, an alkoxy group 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, and 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 ), wherein each of R ^B11 to R ^B15 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 compounds represented by the general formula (B-1) and the compounds represented by the general formula (B-2), in particular, "-C ₆ H ₄ -CH=CH-CH=C(R ^B6 ) ( R ^B7 )” and the compound represented by the general formula (B-2) having “—CH═CH—CH═C(R ^B14 )(R ^B15 )” is preferred.

Specific examples of the compound represented by the general formula (B-1) and the compound represented by the general formula (B-2) are shown below with the following structural formulas (HT-1) to (HT-10). Transport materials are not limited to these.

The content of the total hole-transporting material relative to the total solid content of the photosensitive layer is preferably 20% by mass or more and 48% by mass or less, preferably 25% by mass or more and 45% by mass or less, more preferably 28% by mass or more and 45% by mass or less. is. The content of the hole-transporting material is the total content of the electron-transporting materials when two or more electron-transporting materials are used in combination.

-Electron Transport Materials-
The electron transport material is not particularly limited, but examples include quinone compounds such as chloranil and bromoanil; tetracyanoquinodimethane compounds; 2,4,7-trinitro-9-fluorenone, 2,4,5,7 -Tetranitro-9-fluorenone, fluorenone compounds such as octyl 9-dicyanomethylene-9-fluorenone-4-carboxylate; 2-(4-biphenyl)-5-(4-t-butylphenyl)-1,3, Oxadiazole such as 4-oxadiazole, 2,5-bis(4-naphthyl)-1,3,4-oxadiazole, 2,5-bis(4-diethylaminophenyl)1,3,4-oxadiazole Diazole compounds; xanthone compounds; thiophene compounds; dinaphthoquinone compounds such as 3,3'-di-tert-pentyl-dinaphthoquinone;3,3'-di-tert-butyl-5,5'-dimethyl Diphenoquinone-based compounds such as diphenoquinone and 3,3′,5,5′-tetra-tert-butyl-4,4′-diphenoquinone; polymers having groups composed of the above compounds in the main chain or side chain ; and the like. These electron transport materials may be used singly or in combination of two or more.

Among these, a diphenoquinone-based electron transport material represented by the following general formula (C-1) is preferable from the viewpoint of improving the sensitivity of the photoreceptor.

In general formula (C-1), R ^C11 , R ^C12 , R ^C13 and R ^C14 each independently represent a hydrogen atom, an alkyl group, an alkoxy group, a halogen atom or a phenyl group.

In general formula (C-1), examples of alkyl groups represented by R ^C11 to R ^C14 include linear or branched alkyl groups having 1 or more and 6 or less carbon atoms. , methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, tert-butyl group, pentyl group, hexyl group and the like.
The alkyl groups represented by R ^C11 to R ^C14 may be substituted alkyl groups. A cycloalkyl group, a fluorine-substituted alkyl group, etc. are mentioned as a substituent of a substituted alkyl group.

In general formula (C-1), examples of alkoxy groups represented by R ^C11 to R ^C14 include alkoxy groups having 1 to 6 carbon atoms, and specific examples include methoxy, ethoxy, propoxy, butoxy group and the like.

In general formula (C-1), examples of the halogen atoms represented by R ^C11 to R ^C14 include chlorine, iodine, bromine and fluorine atoms.

In general formula (C-1), the phenyl groups represented by R ^C11 to R ^C14 may be substituted phenyl groups. Substituents for the substituted phenyl group include alkyl groups (eg, alkyl groups having 1 to 6 carbon atoms), alkoxy groups (eg, alkoxy groups having 1 to 6 carbon atoms), biphenyl groups, and the like.

The diphenoquinone-based electron-transporting materials represented by formula (C-1) may be used singly or in combination of two or more.

Hereinafter, the following structural formulas (C-1-1) to (C-1-3) are shown as exemplary compounds of the diphenoquinone-based electron transport material represented by the general formula (C-1), but they are not limited to these. isn't it.

The content of the total electron transport material relative to the total solid content of the photosensitive layer is preferably 4% by mass or more and 30% by mass or less, preferably 6% by mass or more and 25% by mass or less, more preferably 8% by mass or more and 20% by mass or less. be. In addition, the content of the electron transporting material is the total content of the electron transporting materials when two or more electron transporting materials are used in combination.

-Mass ratio of hole-transporting material and electron-transporting material-
The ratio of the hole-transporting material and the electron-transporting material is preferably 50/50 or more and 90/10 or less, more preferably 60/40 or more and 80/20 or less in mass ratio (hole-transporting material/electron-transporting material). be.

-Combination of charge-generating material, hole-transporting material, and electron-transporting material-
The combination of the charge-generating material, the hole-transporting material, and the electron-transporting material is not particularly limited, and combinations of the above materials are used. Among these, the charge-generating material contains a V-type hydroxygallium phthalocyanine pigment, the hole-transporting material contains the compound represented by the general formula (B-1), and the electron-transporting material contains the compound represented by the general formula (C-1 ) from the viewpoint of improving the sensitivity of the photoreceptor. In particular, when a polycarbonate resin that is a homopolymer is used as the binder resin, the hydroxygallium phthalocyanine pigment, the compound represented by the general formula (B-1), and the compound represented by the general formula (C-1) By using the combination of the above, the decrease in sensitivity of the photoreceptor is suppressed. Further, when a combination of a polycarbonate resin which is a homopolymer, a hydroxygallium phthalocyanine pigment, a compound represented by the general formula (B-1), and a compound represented by the general formula (C-1) is used, general Although chemical cracks tend to occur in some cases, chemical cracks are suppressed in the present embodiment because the coefficient of linear expansion α is within the above range.

-Other ingredients-
The single-layer type photosensitive layer may contain other known additives such as surfactants, antioxidants, light stabilizers and heat stabilizers. When the single-layer type photosensitive layer is the surface layer (that is, the outermost layer), the single-layer type photosensitive layer may contain release agents such as fluororesin particles and silicone polymers.

The electrophotographic photoreceptor may be a positively charged electrophotographic photoreceptor or a negatively charged electrophotographic photoreceptor. A photographic photoreceptor is preferred.
The single-layer type photosensitive layer in the positive charging electrophotographic photoreceptor preferably contains a charge control agent as another component, and more preferably contains an electron-donating charge control agent. When the electron-donating charge control agent is contained, a positive charge type photosensitive layer is easily formed. As the charge control agent, conventionally known compounds used as charge control agents for toners can be used.
Electron-donating charge control agents include, for example, azo metal charge control agents, oxycarboxylic acid charge control agents, boron complex charge control agents, iron complex charge control agents, zinc complex charge control agents, and alkylsalicylic acid complex salts. system charge control agents, sulfonic acid pendant resin type charge control agents, and the like.
The charge control agent may be used singly or in combination of two or more.
The content of the charge control agent, particularly the electron-donating charge control agent, is preferably 0.01 parts by mass or more and 20 parts by mass or less, and preferably 0.05 parts by mass, with respect to 100 parts by mass of the binder resin of the photosensitive layer. It is more preferably 10 parts by mass or less, and even more preferably 0.1 parts by mass or more and 5 parts by mass or less.

(Formation of single layer type photosensitive layer)
A single-layer type photosensitive layer is formed using a photosensitive layer-forming coating solution obtained by adding the above components to a solvent.
Examples of 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; Ordinary organic solvents such as cyclic or linear ethers such as These solvents are used alone or in combination of two or more.

Examples of the method for dispersing particles (for example, charge-generating material) in the coating solution for forming the photosensitive layer include media dispersing machines such as ball mills, vibrating ball mills, attritors, sand mills, and horizontal sand mills; stirring, ultrasonic dispersing machines, roll mills; A medialess disperser such as a high pressure homogenizer is used. Examples of the high-pressure homogenizer include a collision system in which the dispersion liquid is dispersed by liquid-liquid collision or liquid-wall collision in a high pressure state, and a penetration system in which a fine flow path is penetrated and dispersed in a high pressure state.

Examples of methods for applying the photosensitive layer-forming coating liquid include dip coating, push-up coating, wire bar coating, spray coating, blade coating, knife coating, and curtain coating.

After applying the coating solution for forming the photosensitive layer, for example, after drying, the photosensitive layer is cooled until it returns to room temperature (eg, 20° C.).
The drying temperature is, for example, 115° C. or higher and 140° C. or lower, preferably 115° C. or higher and 125° C. or lower. Moreover, as drying time, 20 minutes or more and 40 minutes or less are mentioned, for example, 20 minutes or more and 25 minutes or less are preferable.

As described above, as a means for controlling the value of the "linear expansion coefficient α" within the above range, for example, after drying, the set temperature of the control room is lowered in multiple steps, and the temperature of the photosensitive layer is gradually lowered to room temperature (eg, 20°C). A method of cooling to It is presumed that by gradually lowering the set temperature of the temperature control room in multiple steps after drying and gradually cooling, stress is less likely to remain in the photosensitive layer and the value of the coefficient of linear expansion α can be easily controlled within the above range.

As a specific example of the method of lowering the set temperature of the controlled room in multiple stages after drying, for example, after drying the photosensitive layer at the drying temperature, a first cooling step of cooling in the controlled room set to the first cooling temperature. , a second cooling step of cooling in a controlled room set to a second cooling temperature, and a third cooling step of cooling at room temperature (eg, 20° C.).
When passing through the first cooling step, the second cooling step, and the third cooling step, the first cooling temperature is, for example, a range of 80 ° C. or higher and 90 ° C. or lower, and the time of the first cooling step is, for example, 15 minutes or more and 20 minutes or less, the second cooling temperature is, for example, a range of 50 ° C. or more and 60 ° C. or less, and the time of the second cooling step is, for example, a range of 15 minutes or more and 20 minutes or less, The time for the third cooling step is, for example, in the range of 5 minutes or more and 15 minutes or less. In addition, the number of steps of the cooling process is not particularly limited as long as it is two or more steps.

(Characteristics of single layer type photosensitive layer)
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, even more preferably 10 μm to 40 μm.

The coefficient of linear expansion α in the single-layer type photosensitive layer is, as described above, 0.0040 or less, preferably 0.0035 or less, more preferably 0.0030 or less.
In addition, the coefficient of linear expansion α in the single-layer type photosensitive layer is preferably 0.0025 or more, more preferably 0.0026 or more, and even more preferably 0.0027 or more. When the linear expansion coefficient α is 0.0025 or more, the occurrence of scratches on the surface of the photosensitive layer under low temperature and low humidity conditions (for example, in an environment of temperature 10° C. and humidity 15%) is suppressed compared to the case where the linear expansion coefficient α is less than 0.0025. be done. The reason for this is not clear, but a photosensitive layer with a coefficient of linear expansion α of less than 0.0025 is too hard, which accelerates the occurrence of scratches under low temperature and low humidity conditions, whereas the photosensitive layer with a coefficient of linear expansion α of 0.0025 accelerates the occurrence of scratches under low temperature and low humidity conditions. 0025 or more, the photosensitive layer is not too hard and has flexibility, which is presumed to improve the durability under low temperature and low humidity conditions.

[Image forming apparatus (and process cartridge)]
An 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 forming device that forms an electrostatic latent image on the surface of the charged electrophotographic photosensitive member. means, developing means for developing an electrostatic latent image formed on the surface of an electrophotographic photosensitive member with a developer containing toner to form a toner image, and transfer means for transferring the toner image onto the surface of a recording medium; Prepare. As an electrophotographic photoreceptor, the electrophotographic photoreceptor according to the present embodiment is applied.

The image forming apparatus according to the present embodiment includes fixing means for fixing a toner image transferred to the surface of a recording medium; direct transfer for directly transferring a toner image formed on the surface of an electrophotographic photosensitive member to a recording medium. Apparatus of this type: Intermediate transfer that primarily transfers the toner image formed on the surface of the electrophotographic photosensitive member to the surface of the intermediate transfer member, and then secondarily transfers the toner image transferred on the surface of the intermediate transfer member to the surface of the recording medium. A device equipped with a cleaning means for cleaning the surface of the electrophotographic photosensitive member before charging after transferring the toner image; A known image forming apparatus, such as an apparatus equipped with a static eliminating means for eliminating static electricity by means of an electrophotographic photosensitive member; and an apparatus equipped with an electrophotographic photosensitive member heating member for increasing the temperature of the electrophotographic photosensitive member and reducing the relative temperature.

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, and a primary transfer means for primarily transferring a toner image formed on the surface of an electrophotographic photosensitive member to the surface of the intermediate transfer body. A configuration having transfer means and secondary transfer means for secondarily transferring the toner image transferred on the surface of the intermediate transfer member to the surface of the recording medium is applied.

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

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, for example, at least one selected from the group consisting of charging means, electrostatic latent image forming means, developing means, and transfer means.

An example of the image forming apparatus according to the present embodiment will be shown below, but the present invention is not limited to this. Note that the main parts shown in the drawings will be explained, and the explanation of the others will be omitted.

FIG. 2 is a schematic configuration diagram showing an example of an image forming apparatus according to this embodiment.
The image forming apparatus 100 according to the present embodiment includes, as shown in FIG. a transfer device) and an intermediate transfer member 50 . In the image forming apparatus 100 , the exposure device 9 is arranged at a position where the electrophotographic photosensitive member 7 can be exposed through the opening of the process cartridge 300 , and the transfer device 40 transfers the image to the electrophotographic photosensitive member 7 via the intermediate transfer member 50 . 7 , and the intermediate transfer member 50 is arranged so that a part of the intermediate transfer member 50 is in contact with the electrophotographic photosensitive member 7 . Although not shown, it also has a secondary transfer device for transferring the toner image transferred to the intermediate transfer member 50 onto a recording medium (for example, paper). Note that the intermediate transfer member 50, the transfer device 40 (primary transfer device), and the secondary transfer device (not shown) correspond to an example of transfer means.

The process cartridge 300 in FIG. 2 integrates an electrophotographic photosensitive member 7, a charging device 8 (an example of charging means), a developing device 11 (an example of developing means), and a cleaning device 13 (an example of cleaning means) in a housing. supported by The cleaning device 13 has a cleaning blade (an example of a cleaning member) 131 , and the cleaning blade 131 is arranged 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 .

FIG. 2 shows, as an image forming apparatus, a fibrous member 132 (roll-like) that supplies the lubricant 14 to the surface of the electrophotographic photosensitive member 7, and a fibrous member 133 (flat brush-like) that assists cleaning. are shown, but these are placed as needed.

Each configuration of the image forming apparatus according to the present embodiment will be described below.

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

-Exposure equipment-
Examples of the exposure device 9 include an optical device that exposes the surface of the electrophotographic photosensitive member 7 to light such as semiconductor laser light, LED light, and liquid crystal shutter light in a predetermined image. The wavelength of the light source is within the spectral sensitivity region of the electrophotographic photosensitive member. As for the wavelength of semiconductor lasers, near-infrared light having an oscillation wavelength around 780 nm is predominant. However, the wavelength is not limited to this wavelength, and a laser having an oscillation wavelength of 600 nm or a blue laser having an oscillation wavelength of 400 nm or more and 450 nm or less may also be used. A surface emitting laser light source capable of outputting multiple beams is also effective for color image formation.

- Developing device -
As the developing device 11, for example, a general developing device that develops by contacting or non-contacting a developer can be used. 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 adhering 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 them, it is preferable to use a developing roller holding a developer on its surface.

The developer used in the developing device 11 may be a one-component developer containing only toner, or may be a two-component developer containing toner and carrier. Also, the developer may be magnetic or non-magnetic. As these developers, well-known ones are applied.

－Cleaning device－
As the cleaning device 13, a cleaning blade type device having 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 known transfer charger such as a contact type transfer charger using a belt, a roller, a film, a rubber blade, etc., a scorotron transfer charger using corona discharge, a corotron transfer charger, or the like can be used. mentioned.

-Intermediate transfer body-
As the intermediate transfer member 50, a belt-like member (intermediate transfer belt) containing semiconductive polyimide, polyamideimide, polycarbonate, polyarylate, polyester, rubber, or the like is used. Further, as the form of the intermediate transfer body, a drum-shaped one may be used instead of the belt-shaped one.

FIG. 3 is a schematic configuration diagram showing another example of the image forming apparatus according to this embodiment.
The image forming apparatus 120 shown in FIG. 3 is a tandem type multicolor image forming apparatus in which four process cartridges 300 are mounted. 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 each color. Note that the image forming apparatus 120 has the same configuration as the image forming apparatus 100 except that it is a tandem system.

Examples of the present invention will be described below, but the present invention is not limited to the following examples. In the examples, "parts" means "parts by mass" and "%" means "% by mass" unless otherwise specified.

<Example 1>
43.5 parts by mass of a polycarbonate homopolymer (Resin-1) shown in Table 1 as a binder resin, and 1.5 parts by mass of a hydroxygallium phthalocyanine pigment (CGM-1) shown in Table 1 as a charge generation material, 11 parts by mass of the electron transport material (ETM-1) shown in Table 1, 44 parts by mass of the hole transport material (HTM-1) shown in Table 1, and 250 parts by mass of tetrahydrofuran as a solvent are mixed, Using glass beads with a diameter of 1 mmφ, a dispersion treatment was performed for 4 hours in a sand mill to obtain a coating solution for forming a photosensitive layer.

The resulting coating solution for forming a photosensitive layer was applied to an aluminum substrate having a diameter of 30 mm, a length of 244.5 mm and a thickness of 1 mm by dip coating, and dried under the conditions of drying temperature and drying time shown in Table 2. Curing was performed. After that, cooling was performed through the first cooling process, the second cooling process, and the third cooling process at the temperature and time shown in Table 2 to form a single-layer type photosensitive layer having a thickness of 30 μm.
As described above, the photoreceptor of Example 1 was obtained.

<Examples 2 to 10>
Example 1 was repeated except that the type and amount of the binder resin, the type and amount of the charge generation material, the type and amount of the electron transport material, and the type and amount of the hole transport material were changed according to Table 1. Thus, a coating liquid for forming a photosensitive layer was obtained.
The resulting coating solution for forming a photosensitive layer was applied to an aluminum substrate having a diameter of 30 mm, a length of 244.5 mm and a thickness of 1 mm by dip coating, and dried under the conditions of drying temperature and drying time shown in Table 2. Curing was performed. After that, cooling was performed through the first cooling process, the second cooling process, and the third cooling process at the temperature and time shown in Table 2 to form a single-layer type photosensitive layer having a thickness of 30 μm.
As described above, the photoreceptor of each example was obtained.

<Comparative Examples 1 to 9>
Example 1 was repeated except that the type and amount of the binder resin, the type and amount of the charge generation material, the type and amount of the electron transport material, and the type and amount of the hole transport material were changed according to Table 1. Thus, a coating liquid for forming a photosensitive layer was obtained.
The resulting coating solution for forming a photosensitive layer was applied to an aluminum substrate having a diameter of 30 mm, a length of 244.5 mm and a thickness of 1 mm by dip coating, and dried under the conditions of drying temperature and drying time shown in Table 2. Curing was performed. After that, it was cooled only through the first cooling process at the temperature and time shown in Table 2 to form a single-layer type photosensitive layer having a thickness of 30 μm.
As described above, the photoreceptor of each example was obtained. "-" in Table 2 means that the corresponding cooling step was not performed.

<Measurement>
The linear expansion coefficient α of the photosensitive layer of the photoreceptor obtained in each example was measured and calculated by the method described above. Table 2 shows the results.

<Evaluation of chemical crack resistance>
A filter (47 mm in size) manufactured by ADVANTEC (TOYO) was impregnated with oil (oleic acid triglyceride), adhered to 10 axial locations on the surface of the photoreceptor obtained in each example, and allowed to stand for 24 hours. After that, the surface of the photoreceptor was observed using an optical microscope, and chemical crack resistance was evaluated according to the following criteria. Table 2 shows the results.

-Evaluation criteria for chemical crack resistance-
A: One or less chemical cracks occurred.
B: There were 2 or more and 4 or less chemical cracks.
C: 5 or more and 8 or less chemical cracks occurred.
D: Nine or more chemical cracks occurred.

<Evaluation of photosensitive layer surface scratches under low temperature and low humidity>
The photoreceptor obtained in each example was subjected to repeated image formation (specifically, image formation on 6,000 sheets) under a low-temperature and low-humidity environment (temperature: 10°C, humidity: 15%), and then the surface of the photoreceptor was visually observed. Then, the presence or absence of scratches was evaluated according to the following criteria. Table 2 shows the results.

-Evaluation Criteria for Damage on Surface of Photosensitive Layer-
A: No scratches were observed on the surface of the photoreceptor after repeated image formation.
B: Scratches were found on the photoreceptor surface after repeated image formation.

From the above results, it can be seen that chemical cracks are suppressed in this example as compared with the comparative example.

The details of the abbreviations in Tables 1 and 2 are shown below.
- Binder resin -
Resin-1: Polycarbonate resin that is a homopolymer (bisphenol Z homopolymer type polycarbonate resin, having a repeating unit represented by the structural formula (1-3), viscosity average molecular weight: 40000)
Resin-2: Polyarylate resin that is a homopolymer (polyarylate resin of homopolymerization type of bisphenol A, viscosity average molecular weight: 40000)

-Charge generation material-
CGM-1: Hydroxygallium phthalocyanine (V type) pigment. X-ray diffraction spectrum using CuKα characteristic X-ray has diffraction peaks at positions where Bragg angles (2θ ± 0.2°) are at least 7.3°, 16.0°, 24.9°, and 28.0° (Maximum peak wavelength in spectral absorption spectrum in the wavelength range of 600 nm or more and 900 nm or less = 820 nm, average particle size = 0.12 µm, maximum particle size = 0.2 µm, BET specific surface area value = 60 m ² /g).
CGM-2: Y-type titanyl phthalocyanine pigment. An X-ray diffraction spectrum using CuKα characteristic X-rays has diffraction peaks at Bragg angles (2θ±0.2°) of at least 9.6° and 27.3°.

-Electron Transport Materials-
ETM-1: electron transport material ETM-1 having the following structure
ETM-2: electron transport material ETM-2 having the following structure

-Hole transport material-
HTM-1: hole transport material HTM-1 having the following structure
HTM-2: hole transport material HTM-2 having the following structure
HTM-3: hole transport material HTM-3 having the following structure

Reference Signs List 1 Undercoat layer 2 Photosensitive layer 3 Conductive substrate 7 Electrophotographic photoreceptor 8 Charging device 9 Exposure device 11 Developing device 13 Cleaning device 14 Lubricant 40 Transfer device 50 Intermediate transfer member 100 Image forming apparatus 120 Image forming apparatus 131 Cleaning blade 132 Fibrous member (roll shape) 133 Fibrous member (flat brush shape) 300 Process cartridge

Claims (10)

a conductive substrate;
A single-layer type photosensitive layer provided on the conductive substrate and containing a resin that is a homopolymer, a charge generating material, a hole transporting material, and an electron transporting material, wherein the glass transition temperature of the photosensitive layer is Tg a single-layer photosensitive layer having an in-plane linear expansion coefficient α of 0.0040 or less at (Tg+10)° C. or higher and (Tg+30)° C. or lower, where °C;
an electrophotographic photoreceptor. 2. The electrophotographic photoreceptor according to claim 1, wherein the coefficient of linear expansion α is 0.0025 or more. 3. The electrophotographic photoreceptor according to claim 1, wherein the homopolymer resin contains at least one selected from a polycarbonate resin and a polyarylate resin. 4. The electrophotographic photoreceptor according to claim 3, wherein the homopolymer resin contains at least a polycarbonate resin. 5. The electrophotographic photoreceptor according to claim 4, wherein the polycarbonate resin has a repeating unit represented by the following general formula (1).

(In general formula (1), R ¹ and R ² each independently represent a hydrogen atom, a substituted or unsubstituted alkyl group having 5 or less carbon atoms, or a substituted or unsubstituted phenyl group, and R ¹ and R ^2. R ³ and R ⁴ each independently represent a hydrogen atom or a substituted or unsubstituted alkyl group having 3 or less carbon atoms.) The electrophotographic photoreceptor according to any one of claims 1 to 5, wherein the content of the resin that is the homopolymer is 40% by mass or more and 60% by mass or less with respect to the entire photosensitive layer. 7. The electrophotographic photoreceptor according to claim 6, wherein the content of the resin that is the homopolymer is 50% by mass or more and 60% by mass or less with respect to the entire photosensitive layer. the charge generating material comprises a V-type hydroxygallium phthalocyanine pigment;
The hole transport material contains a compound represented by the following general formula (B-1),
The electrophotographic photoreceptor according to any one of claims 1 to 7, wherein the electron transport material contains a compound represented by the following general formula (C-1).

(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 each independently represent a substituted or unsubstituted aryl group _; H ₄ —C(R ^B3 )=C(R ^B4 )(R ^B5 ), or —C ₆ H ₄ —CH=CH—CH=C(R ^B6 )(R ^B7 ), and R ^B3 to R ^B7 are Each independently represents a hydrogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aryl group.)

(In general formula (C-1), R ^C11 , R ^C12 , R ^C13 and R ^C14 each independently represent a hydrogen atom, an alkyl group, an alkoxy group, a halogen atom or a phenyl group.) The electrophotographic photoreceptor according to any one of claims 1 to 8,
A process cartridge that can be attached to and detached from an image forming apparatus. The electrophotographic photoreceptor according to any one of claims 1 to 8;
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 an electrostatic latent image formed on the surface of the electrophotographic photosensitive member with a developer containing toner to form a toner image;
a transfer means for transferring the toner image onto the surface of a recording medium;
An image forming apparatus comprising:

Images