WO2017061476A1

WO2017061476A1 - Electrophotographic photoreceptor, process cartridge, and image-forming device

Info

Publication number: WO2017061476A1
Application number: PCT/JP2016/079639
Authority: WO
Inventors: 智文清水
Original assignee: 京セラドキュメントソリューションズ株式会社
Priority date: 2015-10-07
Filing date: 2016-10-05
Publication date: 2017-04-13
Also published as: CN108139698B; CN108139698A

Abstract

An electrophotographic photoreceptor (101) is provided with a conductive base (102), and a photosensitive layer (103). The photosensitive layer (103) contains at least a charge generating agent, a binder resin, and an additive. The additive is a compound represented by general formula (1). In general formula (1), R₁ and R₂ independently represent an electron attractive group. Alternatively, R₁ represents a hydrogen atom, and R₂ represents an electron attractive group. In general formula (1), preferably, R₁ and R₂ independently represent a halogen atom or a nitro group, or R₁ represents a hydrogen atom and R₂ represents a halogen atom or a nitro group.

Description

Electrophotographic photosensitive member, process cartridge, and image forming apparatus

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

The electrophotographic photoreceptor is used in an electrophotographic image forming apparatus. The electrophotographic photoreceptor includes a photosensitive layer. The photosensitive layer contains, for example, a charge generating agent, a charge transporting agent (for example, a hole transporting agent), and a resin (binder resin) for binding them. As the electrophotographic photosensitive member, for example, a multilayer electrophotographic photosensitive member or a single layer type electrophotographic photosensitive member is used. The multilayer electrophotographic photoreceptor includes, as a photosensitive layer, a charge generation layer having a charge generation function and a charge transport layer having a charge transport function. The single layer type electrophotographic photosensitive member includes a single layer type photosensitive layer having functions of charge generation and charge transport as a photosensitive layer.

For example, in order to suppress the occurrence of fog in an image to be formed, a single layer type electrophotographic photosensitive member described in Patent Document 1 has been studied. This single layer type electrophotographic photoreceptor includes a conductive substrate and a photosensitive layer. The outermost layer of the photoreceptor is the photosensitive layer. The photosensitive layer contains at least one of polycarbonate and polyarylate as a binder resin and an olefin polymer.

JP 2011-13365 A

However, the electrophotographic photoreceptor described in Patent Document 1 is insufficient in suppressing the occurrence of fog in the formed image.

The present invention has been made in view of the above problems, and an object thereof is to provide an electrophotographic photosensitive member capable of suppressing the occurrence of fogging in an image to be formed. Another object of the present invention is to provide a process cartridge and an image forming apparatus that can suppress the occurrence of fogging in an image to be formed.

The electrophotographic photoreceptor of the present invention comprises a conductive substrate and a photosensitive layer. The photosensitive layer contains at least a charge generator, a binder resin, and an additive. The additive is a compound represented by the following general formula (1).

In the general formula (1), R ₁ and R ₂ each independently represents an electron withdrawing group. Alternatively, R ₁ represents a hydrogen atom and R ₂ represents an electron withdrawing group.

The process cartridge of the present invention includes the above-described electrophotographic photosensitive member.

An image forming apparatus of the present invention includes the above-described electrophotographic photosensitive member, a charging unit, an exposure unit, a developing unit, and a transfer unit. The charging unit charges the surface of the electrophotographic photosensitive member. The exposure unit exposes the charged surface of the electrophotographic photosensitive member to form an electrostatic latent image on the surface of the electrophotographic photosensitive member. The developing unit develops the electrostatic latent image as a toner image. The transfer unit transfers the toner image from the electrophotographic photosensitive member to a transfer target.

According to the present invention, it is possible to provide an electrophotographic photosensitive member capable of suppressing the occurrence of fogging in the formed image. In addition, according to the present invention, it is possible to provide a process cartridge and an image forming apparatus that can suppress the occurrence of fogging in a formed image.

1 is a schematic cross-sectional view illustrating an example of an electrophotographic photosensitive member according to a first embodiment of the present invention. 1 is a schematic cross-sectional view illustrating an example of an electrophotographic photosensitive member according to a first embodiment of the present invention. It is a schematic sectional drawing which shows another example of the electrophotographic photoreceptor which concerns on 1st embodiment of this invention. It is a schematic sectional drawing which shows another example of the electrophotographic photoreceptor which concerns on 1st embodiment of this invention. It is the schematic which shows an example of a structure of the image forming apparatus which concerns on 2nd embodiment of this invention. It is the schematic which shows another example of a structure of the image forming apparatus which concerns on 2nd embodiment of this invention.

Hereinafter, embodiments of the present invention will be described in detail. However, the present invention is not limited to the following embodiments. The present invention can be implemented with appropriate modifications within the scope of the object of the present invention. In addition, about the location where description overlaps, although description may be abbreviate | omitted suitably, the summary of invention is not limited.

Hereinafter, a compound and its derivatives may be generically named by adding “system” after the compound name. In addition, when “polymer” is added after the compound name to indicate the polymer name, it means that the repeating unit of the polymer is derived from the compound or a derivative thereof.

Hereinafter, a halogen atom, an alkyl group, an alkoxy group, and an aryl group will be described.

The halogen atom is, for example, fluorine (fluoro group), chlorine (chloro group) or bromine (bromo group).

The alkyl group is, for example, an alkyl group having 1 to 6 carbon atoms. The alkyl group having 1 to 6 carbon atoms is a linear or branched alkyl group having 1 to 6 carbon atoms that is unsubstituted. Examples of the alkyl group having 1 to 6 carbon atoms include methyl group, ethyl group, propyl group, isopropyl group, n-butyl group, sec-butyl group, tert-butyl group, pentyl group, isopentyl group, neopentyl group Or a hexyl group.

The alkoxy group is, for example, an alkoxy group having 1 to 6 carbon atoms. The alkoxy group having 1 to 6 carbon atoms is a linear or branched alkoxy group having 1 to 6 carbon atoms which is unsubstituted. Examples of alkoxy groups having 1 to 6 carbon atoms include methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, sec-butoxy, tert-butoxy, pentyloxy, Examples thereof include a pentyloxy group, a neopentyloxy group, and a hexyloxy group.

The aryl group is, for example, an aryl group having 6 to 14 carbon atoms. Examples of the aryl group having 6 to 14 carbon atoms include an unsubstituted aromatic monocyclic hydrocarbon group having 6 to 14 carbon atoms and an unsubstituted aromatic condensed bicyclic carbon group having 6 to 14 carbon atoms. A hydrogen group or an unsubstituted aromatic condensed tricyclic hydrocarbon group having 6 to 14 elemental atoms; Examples of the aryl group having 6 to 14 carbon atoms include a phenyl group, a naphthyl group, an anthryl group, and a phenanthryl group.

<First embodiment: electrophotographic photoreceptor>
The first embodiment relates to an electrophotographic photoreceptor (hereinafter sometimes referred to as a photoreceptor). The photoreceptor according to the present embodiment may be a single-layer photoreceptor or a laminated photoreceptor. The photoreceptor includes a conductive substrate and a photosensitive layer. The photosensitive layer contains at least a charge generating agent, a binder resin, and an additive. The additive is a compound represented by general formula (1) (hereinafter sometimes referred to as compound (1)).

According to the photoconductor of the present embodiment, it is possible to suppress the occurrence of fog in the formed image. The reason is presumed as follows. When an image is formed using a photoreceptor and toner, the frictional charging of the toner may be insufficient. In particular, when an image is formed at a high speed by setting the linear speed of the photosensitive member to be high, or when an image is formed continuously for a long time, the frictional charging of the toner tends to be insufficient. Since the toner with insufficient frictional charging adheres to the non-exposed portion (portion other than the electrostatic latent image) of the photoreceptor, an image defect called “fogging” may be caused in the formed image.

The photosensitive layer of the photoreceptor of this embodiment contains compound (1) as an additive. At least one electron withdrawing group is bonded to two para positions of two phenyl groups in the compound (1). By containing the compound (1) having such a structure in the photosensitive layer, the difference between the photosensitive layer and the toner in the triboelectric charging series can be increased. Thereby, the toner can be sufficiently frictionally charged when the toner comes into contact with the photosensitive layer. As a result, it is possible to suppress the occurrence of fog caused by toner (for example, uncharged toner) with insufficient frictional charging.

Further, the photosensitive layer of the photoreceptor of this embodiment contains the compound (1) as an additive. By containing the compound (1) as an additive, it is considered that the following advantages are obtained as compared with the case where atoms having high electronegativity are introduced into the binder resin. First, when a resin (for example, polyvinyl chloride) into which atoms having high electronegativity are introduced and a polycarbonate resin are used in combination as the binder resin, it is difficult to uniformly disperse these resins. Therefore, a resin into which atoms having high electronegativity are introduced may be localized on the surface of the photosensitive layer. However, the photosensitive layer of the photoreceptor of this embodiment contains the compound (1) as an additive. Thereby, there exists a tendency for a compound (1) to disperse | distribute uniformly in a photosensitive layer. As a result, according to the photoconductor of the present embodiment, it is easy to suppress the occurrence of fog, particularly when an image is formed at a high speed or when an image is formed continuously for a long time. Secondly, when a resin (for example, polyvinyl chloride) into which atoms having high electronegativity are introduced is contained in the photosensitive layer, the resin may block light exposed to the photosensitive layer. However, the compound (1) contained in the photosensitive layer of the photoconductor of the present embodiment does not easily block light exposed to the photosensitive layer. As a result, it is considered that the electrical characteristics can be improved according to the photoreceptor of this embodiment. Thirdly, the compound (1) is a monomer. Therefore, the compound (1) is likely to enter a gap (void) formed by the binder resin in the photosensitive layer, as compared with a polymer-introduced resin having a high electronegativity. When the compound (1) enters the void and fills the void, it becomes difficult for the oil to enter the photosensitive layer. As a result, it is considered that occurrence of cracks (oil cracks) in the photosensitive layer due to oil adhesion can be suppressed.

<1. Single-layer type photoreceptor>
Hereinafter, with reference to FIGS. 1A and 1B, a case where the photoconductor 101 is a single-layer photoconductor will be described. 1A and 1B are schematic cross-sectional views showing a single-layer type photoreceptor that is an example of the photoreceptor 101 according to the present embodiment.

As shown in FIG. 1A, the single-layer type photoreceptor as the photoreceptor 101 includes, for example, a conductive substrate 102 and a photosensitive layer 103. When the photoreceptor 101 is a single layer type photoreceptor, a single layer type photosensitive layer 103 c is provided as the photosensitive layer 103. As shown in FIG. 1A, a single-layer type photosensitive layer 103 c may be directly provided on the conductive substrate 102.

Further, as shown in FIG. 1B, the single layer type photoreceptor as the photoreceptor 101 may include a conductive substrate 102, a single layer type photosensitive layer 103c, and an intermediate layer (undercoat layer) 104. The intermediate layer 104 is provided, for example, between the conductive substrate 102 and the single-layer type photosensitive layer 103c. A protective layer (not shown) may be provided on the single-layer type photosensitive layer 103c.

The thickness of the single-layer type photosensitive layer 103c is not particularly limited as long as the function as a single-layer type photosensitive layer can be sufficiently expressed. The thickness of the single-layer type photosensitive layer 103c is preferably 5 μm or more and 100 μm or less, and more preferably 10 μm or more and 50 μm or less.

When the photosensitive layer 103 is a single-layer type photosensitive layer 103c, the single-layer type photosensitive layer 103c contains at least a charge generator, a compound (1) as an additive, and a binder resin. The single-layer type photosensitive layer 103c may further contain an electron transport agent and a hole transport agent in addition to the charge generator, the compound (1) as an additive, and the binder resin. The single-layer type photosensitive layer 103c may further contain various additives (hereinafter sometimes referred to as other additives) other than the compound (1) as necessary. The compound (1), binder resin, charge generator, electron transport agent, hole transport agent, and other additives as additives will be described later.

<2. Multilayer photoreceptor>
Hereinafter, with reference to FIGS. 2A and 2B, a case where the photoconductor 101 is a multilayer photoconductor will be described. FIG. 2A and FIG. 2B are schematic cross-sectional views showing a laminated type photoconductor that is another example of the photoconductor 101 according to this embodiment.

As shown in FIG. 2A, the stacked type photoconductor as the photoconductor 101 includes a conductive substrate 102 and a photosensitive layer 103. The multilayer photoreceptor as the photoreceptor 101 includes a charge generation layer 103 a and a charge transport layer 103 b as the photosensitive layer 103.

As shown in FIG. 2A, the photosensitive layer 103 may be provided directly on the conductive substrate 102. Alternatively, as shown in FIG. 2B, an intermediate layer (undercoat layer) 104 may be provided between the conductive substrate 102 and the photosensitive layer 103. A protective layer (not shown) may be provided on the photosensitive layer 103.

The thickness of the charge generation layer 103a and the charge transport layer 103b is not particularly limited as long as the functions as the respective layers can be sufficiently expressed. The thickness of the charge generation layer 103a is preferably 0.01 μm or more and 5 μm or less, and more preferably 0.1 μm or more and 3 μm or less. The thickness of the charge transport layer 103b is preferably 2 μm or more and 100 μm or less, and more preferably 5 μm or more and 50 μm or less.

When the charge generation layer 103a and the charge transport layer 103b are provided as the photosensitive layer 103, the charge transport layer 103b contains at least the compound (1) as an additive and a binder resin. The charge transport layer 103b may further contain a hole transport agent in addition to the compound (1) as an additive and the binder resin. The charge transport layer 103b may further contain an electron acceptor compound and other additives as necessary. The compound (1), binder resin, hole transport agent, electron acceptor compound, and other additives as additives will be described later.

The charge generation layer 103a in the photosensitive layer 103 contains, for example, a charge generation agent. The charge generation layer 103a may contain a binder resin for the charge generation layer 103a (hereinafter sometimes referred to as “base resin”). The charge generation layer 103a may contain other additives as necessary. The charge generator, base resin, and other additives will be described later.

In order to particularly suppress the occurrence of fog in the formed image, the photosensitive layer 103 containing the compound (1) is preferably disposed as the outermost surface layer of the photoreceptor 101. Specifically, the single-layer type photosensitive layer 103 c or the charge transport layer 103 b containing the compound (1) is preferably disposed as the outermost surface layer of the photoreceptor 101. This is because the compound (1) contained in the outermost surface layer can increase the difference in the triboelectric charging series between the outermost surface layer in contact with the toner and the toner. As a result, as described above, it is possible to suppress the occurrence of fog caused by toner with insufficient frictional charging (for example, uncharged toner).

The structure of the single layer type photoreceptor and the multilayer type photoreceptor, which are photoreceptors, has been described above with reference to FIGS. 1A, 1B, 2A, and 2B. Next, elements common to the single layer type photoreceptor and the multilayer type photoreceptor, which are photoreceptors, will be described.

<3. Conductive substrate>
The conductive substrate is not particularly limited as long as it can be used as the conductive substrate of the photoreceptor. The conductive substrate may be formed of a material having at least a surface portion having conductivity. An example of the conductive substrate is a conductive substrate formed of a conductive material. Another example of the conductive substrate is a conductive substrate coated with a conductive material. Examples of the conductive material include aluminum, iron, copper, tin, platinum, silver, vanadium, molybdenum, chromium, cadmium, titanium, nickel, palladium, indium, stainless steel, and brass. These conductive materials may be used alone or in combination of two or more (for example, as an alloy). Among these materials having conductivity, aluminum or an aluminum alloy is preferable because charge transfer from the photosensitive layer to the conductive substrate is good.

The shape of the conductive substrate is appropriately selected according to the structure of the image forming apparatus described later in the second embodiment. Examples of the shape of the conductive substrate include a sheet shape or a drum shape. The thickness of the conductive substrate is appropriately selected according to the shape of the conductive substrate.

<4. Charge generator>
When the photoreceptor is a single layer type photoreceptor, the single layer type photosensitive layer contains, for example, a charge generating agent. When the photoreceptor is a multilayer photoreceptor, the charge generation layer contains, for example, a charge generation agent.

The charge generator is not particularly limited as long as it is a charge generator for a photoreceptor. Examples of the charge generator include phthalocyanine pigments, dithioketopyrrolopyrrole pigments, metal-free naphthalocyanine pigments, metal naphthalocyanine pigments, squaraine pigments, indigo pigments, azulenium pigments, cyanine pigments, inorganic photoconductive materials (for example, selenium , Selenium-tellurium, selenium-arsenic, cadmium sulfide, or amorphous silicon) powder, pyrylium salt, ansanthrone pigment, triphenylmethane pigment, selenium pigment, toluidine pigment, pyrazoline pigment, or quinacridone pigment Can be mentioned.

Examples of the phthalocyanine pigment include metal-free phthalocyanine represented by the chemical formula (C-1) or metal phthalocyanine. Examples of the metal phthalocyanine include titanyl phthalocyanine represented by the chemical formula (C-2), hydroxygallium phthalocyanine, or chlorogallium phthalocyanine. The phthalocyanine pigment may be crystalline or non-crystalline. The crystal shape of the phthalocyanine pigment (for example, α type, β type, Y type, V type, or II type) is not particularly limited, and phthalocyanine pigments having various crystal shapes are used.

Examples of the crystal of metal-free phthalocyanine include metal-free phthalocyanine X-type crystals (hereinafter sometimes referred to as “X-type metal-free phthalocyanine”). Examples of the crystal of titanyl phthalocyanine include α-type, β-type, or Y-type crystal of titanyl phthalocyanine (hereinafter sometimes referred to as “α-type, β-type, or Y-type titanyl phthalocyanine”). Examples of the crystal of hydroxygallium phthalocyanine include a V-type crystal of hydroxygallium phthalocyanine. Examples of chlorogallium phthalocyanine crystals include chlorogallium phthalocyanine type II crystals. X-type metal-free phthalocyanine or Y-type titanyl phthalocyanine is preferable, and X-type metal-free phthalocyanine is more preferable because it has a high quantum yield in the wavelength region of 700 nm or more.

A charge generator having an absorption wavelength in a desired region may be used alone, or two or more charge generators may be used in combination. Further, for example, in a digital optical image forming apparatus (for example, a laser beam printer or a facsimile using a light source such as a semiconductor laser), it is preferable to use a photoconductor having sensitivity in a wavelength region of 700 nm or more. Therefore, for example, phthalocyanine pigments are preferred, metal-free phthalocyanines or titanyl phthalocyanines are more preferred, and X-type metal-free phthalocyanines are particularly preferred. A charge generating agent may be used individually by 1 type, and may be used in combination of 2 or more type.

An santhrone pigment is preferably used as a charge generating agent in a photoreceptor applied to an image forming apparatus using a short wavelength laser light source (for example, a laser light source having a wavelength of about 350 nm to about 550 nm).

When the photoreceptor is a multilayer photoreceptor, the content of the charge generating agent is preferably 5 parts by mass or more and 1000 parts by mass or less with respect to 100 parts by mass of the base resin contained in the charge generation layer. More preferably, it is at least 500 parts by mass.

When the photoreceptor is a single layer type photoreceptor, the content of the charge generating agent is 0.1 parts by mass or more and 50 parts by mass or less with respect to 100 parts by mass of the binder resin contained in the single layer type photosensitive layer. It is preferably 0.5 parts by mass or more and 30 parts by mass or less.

<5. Compound (1)>
When the photoreceptor is a single layer type photoreceptor, the single layer type photosensitive layer as the photosensitive layer contains the compound (1) as an additive. When the photoreceptor is a laminated photoreceptor, the charge transport layer in the photosensitive layer contains the compound (1) as an additive. By containing the compound (1), it is possible to suppress the occurrence of fogging in the formed image as described above.

Compound (1) is represented by the following general formula (1).

In the general formula (1), R ₁ and R ₂ each independently represent an electron withdrawing group. Alternatively, R ₁ represents a hydrogen atom and R ₂ represents an electron withdrawing group. R ₁ and R ₂ are not both hydrogen atoms. When R ₁ and R ₂ each independently represent an electron withdrawing group, R ₁ and R ₂ may represent the same type of electron withdrawing group, or represent different types of electron withdrawing groups. May be.

Definitions and examples of electron withdrawing groups are as described in “Chemical Dictionary First Edition” issued by Tokyo Chemical Co., Ltd. Specifically, the electron withdrawing group is a group that is more likely to attract electrons to the bonding atom side (R ₁ and R ₂ side in the general formula (1)) than the hydrogen atom. The electron withdrawing group is, for example, a group having a positive substituent constant. Examples of the electron withdrawing group include a halogen atom, —NO ₂ (nitro group), —CN (cyano group), —CF ₃ (trifluoromethyl group), —CCl ₃ (trichloromethyl group), —CHO ( Formyl group), —CO—CH ₃ (acetyl group), —CO—OC ₂ H ₅ (ethoxycarbonyl group), —COOH (carboxyl group), —SO ₂ CH ₃ (methylsulfonyl group) or —SO ₃ H ( Sulfo group).

The groups shown below are electron donating groups. For example, —OH (hydroxyl group), —OCH ₃ (methoxy group), —O—CO—CH ₃ (methylcarbonyloxy group), —NH ₂ (amino group), —N (CH ₃ ) ₂ (dimethylamino group) ), —N (CH ₂ CH ₃ ) ₂ (diethylamino group), —NH—CO—CH ₃ (methylcarbamoyl group), alkyl group and aryl group are electron donating groups. The electron donating group is a group that easily gives an electron to the bonding atom side as compared with a hydrogen atom. The electron donating group is, for example, a group having a negative substituent constant. The definition and examples of the electron donating group are as described in “Chemical Dictionary First Edition” issued by Tokyo Chemical Co., Ltd.

In order to suppress the occurrence of fogging in an image to be formed, in the general formula (1), it is preferred that R ₁ and R ₂ are each independently a halogen atom or a nitro group. Alternatively, R ₁ represents a hydrogen atom, R ₂ preferably represents a halogen atom or a nitro group.

In a more preferred example for suppressing the occurrence of fog in the formed image, in the general formula (1), R ₁ and R ₂ each independently represent a halogen atom. “Each independently represents a halogen atom” means, for example, that R ₁ may be a fluoro group and R ₂ may be a chloro group. In order to suppress the occurrence of fog in the formed image, it is particularly preferable that R ₁ and R ₂ each represent a chloro group, as represented by the following chemical formula (A-1). Hereinafter, the compound represented by the chemical formula (A-1) may be referred to as a compound (A-1).

In another more preferable example for suppressing the occurrence of fogging in the formed image, in general formula (1), R ₁ represents a hydrogen atom and R ₂ represents a halogen atom. In order to suppress the occurrence of fog in the formed image, it is particularly preferable that R ₁ represents a hydrogen atom and R ₂ represents a chloro group, as represented by the following chemical formula (A-2). Hereinafter, the compound represented by the chemical formula (A-2) may be referred to as a compound (A-2).

In another more preferable example for suppressing the occurrence of fogging in the formed image, in the general formula (1), R ₁ and R ₂ each represent a nitro group. When R ₁ and R ₂ each represent a nitro group, the compound (1) is represented by the following chemical formula (A-4). Hereinafter, the compound represented by the chemical formula (A-4) may be referred to as a compound (A-4).

In another more preferable example for suppressing the occurrence of fogging in the formed image, in general formula (1), R ₁ represents a hydrogen atom and R ₂ represents a nitro group. When R ₁ represents a hydrogen atom and R ₂ represents a nitro group, the compound (1) is represented by the following chemical formula (A-5). Hereinafter, the compound represented by the chemical formula (A-5) may be referred to as a compound (A-5).

When the photoreceptor is a single layer type photoreceptor, the content of the compound (1) as an additive is 10 parts by mass or more and 40 parts by mass with respect to 100 parts by mass of the binder resin contained in the single layer type photosensitive layer. The following is preferable. When the photoreceptor is a multilayer photoreceptor, the content of the compound (1) as an additive is 10 parts by mass or more and 40 parts by mass or less with respect to 100 parts by mass of the binder resin contained in the charge transport layer. It is preferable. When the content of the compound (1) is 10 parts by mass or more and 40 parts by mass or less, the occurrence of fog in the formed image can be particularly suppressed, and in addition, the electrical characteristics of the photoreceptor can be improved.

When the photoreceptor is a single layer type photoreceptor, the content of the compound (1) as an additive is 10 parts by mass or more and 30 parts by mass with respect to 100 parts by mass of the binder resin contained in the single layer type photosensitive layer. The following is more preferable. When the photoreceptor is a multilayer photoreceptor, the content of the compound (1) as an additive is 10 parts by mass or more and 30 parts by mass or less with respect to 100 parts by mass of the binder resin contained in the charge transport layer. It is more preferable. When the content of the compound (1) is 10 parts by mass or more, the occurrence of fog in the formed image can be particularly suppressed. When the content of the compound (1) is 30 parts by mass or less, the electrical characteristics of the photoreceptor can be particularly improved.

<6. Electron Transfer Agent and Electron Acceptor Compound>
When the photoreceptor is a single layer type photoreceptor, the single layer type photosensitive layer may contain an electron transport agent, if necessary. Thereby, the single-layer type photosensitive layer can transport electrons, and it becomes easy to impart bipolar (bipolar) characteristics to the single-layer type photosensitive layer. When the photoreceptor is a multilayer photoreceptor, the charge transport layer may contain an electron acceptor compound as necessary. Thereby, it becomes easy to improve the hole transport ability of the hole transport agent.

Examples of electron transfer agents or electron acceptor compounds include quinone compounds, diimide compounds, hydrazone compounds, malononitrile compounds, thiopyran compounds, trinitrothioxanthone compounds, 3,4,5,7-tetranitro-9- Fluorenone compounds, dinitroanthracene compounds, dinitroacridine compounds, tetracyanoethylene, 2,4,8-trinitrothioxanthone, dinitrobenzene, dinitroacridine, succinic anhydride, maleic anhydride, or dibromomaleic anhydride . Examples of quinone compounds include diphenoquinone compounds, azoquinone compounds, anthraquinone compounds, naphthoquinone compounds, nitroanthraquinone compounds, and dinitroanthraquinone compounds. An electron transfer agent may be used individually by 1 type, and may be used in combination of 2 or more type. An electron acceptor compound may also be used individually by 1 type, and may be used in combination of 2 or more type.

Specific examples of the electron transfer agent include a compound represented by the general formula (2). In order to suppress the occurrence of fogging in the formed image, the compound represented by the general formula (2) is preferable.

In General Formula (2), R ₂₁ and R ₂₂ may each independently have an alkyl group that may have a substituent, an alkoxy group that may have a substituent, or a substituent. Represents a good aryl group. When R ₂₁ and R ₂₂ are alkyl groups having a substituent, the substituent is selected from the group consisting of an alkoxy group and a halogen atom. When R ₂₁ and R ₂₂ are an alkoxy group having a substituent, the substituent is selected from the group consisting of an alkoxy group and a halogen atom. When R ₂₁ and R ₂₂ are an aryl group having a substituent, the substituent is selected from the group consisting of an alkyl group, an alkoxy group, and a halogen atom.

R ₂₁ and R ₂₂ are each independently preferably an alkyl group or an alkoxy group, and more preferably an alkyl group.

When R ₂₁ and R ₂₂ are alkyl groups, the alkyl group is preferably an alkyl group having 1 to 6 carbon atoms, preferably an alkyl group having 1 to 4 carbon atoms, and having 1 to 2 carbon atoms. The following alkyl groups are more preferred.

R ₂₁ and R ₂₂ are preferably different from each other. For example, R ₂₁ may be an alkyl group and R ₂₂ may be an alkoxy group. For example, when R ₂₁ and R ₂₂ are both alkyl groups, R ₂₁ may be a methyl group and R ₂₂ may be an ethyl group.

In general formula (2), R ₂₃ , R ₂₄ , and R ₂₅ are each independently a hydrogen atom, an alkyl group that may have a substituent, an alkoxy group that may have a substituent, or a substituent. An aryl group which may have a group is represented. When R ₂₃ , R ₂₄ , and R ₂₅ are an alkyl group having a substituent, the substituent is selected from the group consisting of an alkoxy group and a halogen atom. When R ₂₃ , R ₂₄ , and R ₂₅ are an alkoxy group having a substituent, the substituent is selected from the group consisting of an alkoxy group and a halogen atom. When R ₂₃ , R ₂₄ , and R ₂₅ are an aryl group having a substituent, the substituent is selected from the group consisting of an alkyl group, an alkoxy group, and a halogen atom. R ₂₃ , R ₂₄ and R ₂₅ preferably represent a hydrogen atom.

R ₂₆ and R ₂₇ each independently represents a hydrogen atom, an alkyl group, an alkoxy group, or a halogen atom. R ₂₆ and R ₂₇ preferably represent a hydrogen atom.

In order to improve the electrical characteristics of the photoreceptor and suppress the occurrence of fog in the formed image, it is preferable that R ₂₁ to R ₂₇ in the general formula (2) represent the following groups. R ₂₁ and R ₂₂ each independently represents an alkyl group having 1 to 6 carbon atoms. R ₂₃ , R ₂₄ , and R ₂₅ represent a hydrogen atom. R ₂₆ and R ₂₇ represent a hydrogen atom.

As an example of the compound (2), N, N′-bis (2-methyl-6-ethylphenyl) naphthalene-1,4,5,8-tetracarboxylic acid diimide (represented by the chemical formula (E-1)) Compound, which may hereinafter be referred to as “compound (E-1)”), N, N′-bis (2-ethyl-6-methylphenyl) naphthalene-1,4,5,8-tetracarboxylic acid diimide, N, N′-bis (2,4-dimethyl-6-ethylphenyl) naphthalene-1,4,5,8-tetracarboxylic acid diimide, N, N′-bis (2-methyl-6-ethoxyphenyl) naphthalene -1,4,5,8-tetracarboxylic acid diimide, N, N′-bis (2-methyl-6-methoxyphenyl) naphthalene-1,4,5,8-tetracarboxylic acid diimide, or N, N ′ -Bis (2-methyl-6- Butoxyethyl phenyl) naphthalene 1,4,5,8-tetracarboxylic diimide and the like.

As another specific example of the electron transfer agent, a compound represented by the general formula (3), (4) or (5) can be given.

In general formulas (3), (4) and (5), R ₂₈ to R ₃₅ each independently have a hydrogen atom, a cyano group, an alkyl group which may have a substituent, or a substituent. An alkenyl group which may have a substituent, an alkoxy group which may have a substituent, an alkoxycarbonyl group which may have a substituent, an aryl group which may have a substituent, or a heterocyclic ring which may have a substituent Represents a group. In general formula (5), each R ₃₆ independently represents a hydrogen atom, a halogen atom, a cyano group, an alkyl group which may have a substituent, an alkenyl group which may have a substituent, or a substituent. It represents an alkoxy group that may have, an alkoxycarbonyl group that may have a substituent, an aryl group that may have a substituent, or a heterocyclic group that may have a substituent.

In general formulas (3), (4) and (5), the alkyl group represented by R ₂₈ to R ₃₆ is preferably an alkyl group having 1 to 6 carbon atoms, and having 1 to 5 carbon atoms. An alkyl group is more preferable, and a methyl group, 1,1-dimethylpropyl group, or tert-butyl group is particularly preferable. The alkyl group may have a substituent. Examples of the substituent include a halogen atom, a hydroxyl group, an alkoxy group having 1 to 6 carbon atoms, an aryl group having 6 to 14 carbon atoms which may further have a substituent, or a cyano group. . The number of substituents is not particularly limited, but is preferably 3 or less. Examples of the substituent further included in the aryl group having 6 to 14 carbon atoms as the substituent include a halogen atom, a hydroxyl group, an alkyl group having 1 to 6 carbon atoms, and an alkoxy having 1 to 6 carbon atoms. Group, nitro group, cyano group, alkanoyl group having 2 to 7 carbon atoms (a group in which an alkyl group having 1 to 6 carbon atoms is bonded to a carbonyl group), benzoyl group, phenoxy group, 2 to 7 carbon atoms Examples thereof include the following alkoxycarbonyl groups (groups in which an alkoxy group having 1 to 6 carbon atoms is bonded to a carbonyl group) or phenoxycarbonyl groups.

In the general formulas (3), (4) and (5), the alkenyl group represented by R ₂₈ to R ₃₆ is, for example, linear or branched and unsubstituted C 2 or more and 6 or less. An alkenyl group. The alkenyl group having 2 to 6 carbon atoms has, for example, 1 to 3 double bonds. Examples of the alkenyl group having 2 to 6 carbon atoms include a vinyl group, a propenyl group, a butenyl group, a pentenyl group, a pentadienyl group, a hexenyl group, and a hexadienyl group. The alkenyl group may have a substituent. Examples of the substituent include a halogen atom, a hydroxyl group, an alkoxy group having 1 to 6 carbon atoms, an aryl group having 6 to 14 carbon atoms, or a cyano group. The number of substituents is not particularly limited, but is preferably 3 or less.

In general formulas (3), (4) and (5), the alkoxy group represented by R ₂₈ to R ₃₆ is preferably an alkoxy group having 1 to 6 carbon atoms, and having 1 to 3 carbon atoms. An alkoxy group is more preferable, and a methoxy group is particularly preferable. The alkoxy group may have a substituent. Examples of the substituent include a halogen atom, a hydroxyl group, an alkoxy group having 1 to 6 carbon atoms, an aryl group having 6 to 14 carbon atoms, or a cyano group. As the substituent, a phenyl group is preferable. The number of substituents is not particularly limited, but is preferably 3 or less, more preferably 1.

In the general formulas (3), (4) and (5), the alkoxycarbonyl group represented by R ₂₈ to R ₃₆ is, for example, an alkoxycarbonyl group having 2 to 7 carbon atoms. An alkoxycarbonyl group having 2 to 7 carbon atoms is a group in which a linear or branched, unsubstituted alkoxy group having 1 to 6 carbon atoms is bonded to a carbonyl group. The alkoxycarbonyl group may have a substituent. Examples of the substituent include a halogen atom, a hydroxyl group, an alkoxy group having 1 to 6 carbon atoms, an aryl group having 6 to 14 carbon atoms, or a cyano group. The number of substituents is not particularly limited, but is preferably 3 or less.

In general formulas (3), (4) and (5), the aryl group represented by R ₂₈ to R ₃₆ is preferably an aryl group having 6 to 14 carbon atoms, and more preferably a phenyl group. The aryl group may have a substituent. Examples of the substituent include a halogen atom, a hydroxyl group, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, a nitro group, a cyano group, and an alkanoyl having 2 to 7 carbon atoms. A group (a group in which an alkyl group having 1 to 6 carbon atoms is bonded to a carbonyl group), a benzoyl group, a phenoxy group, an alkoxycarbonyl group having 2 to 7 carbon atoms (a carbonyl group having 1 to 6 carbon atoms) A group to which an alkoxy group is bonded), a phenoxycarbonyl group, an aryl group having 6 to 14 carbon atoms, or a biphenyl group. The number of substituents is not particularly limited, but is preferably 3 or less.

In the general formulas (3), (4) and (5), the heterocyclic group represented by R ₂₈ to R ₃₆ represents, for example, one or more heteroatoms selected from the group consisting of N, S and O A 5- or 6-membered monocyclic heterocyclic group; a heterocyclic group in which such monocycles are condensed; or a heterocycle in which such a monocycle is condensed with a 5- or 6-membered hydrocarbon ring It is a cyclic group. When the heterocyclic group is a condensed ring, the number of rings contained in the condensed ring is preferably 3 or less. Examples of the substituent that the heterocyclic group may have include, for example, a halogen atom, a hydroxyl group, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, a nitro group, a cyano group, Alkanoyl group having 2 to 7 carbon atoms (a group in which an alkyl group having 1 to 6 carbon atoms is bonded to a carbonyl group), benzoyl group, phenoxy group, alkoxycarbonyl group having 2 to 7 carbon atoms (carbonyl group) Group having an alkoxy group having 1 to 6 carbon atoms bonded thereto, or a phenoxycarbonyl group. The number of substituents is not particularly limited, but is preferably 3 or less.

When the photoreceptor is a multilayer photoreceptor, the content of the electron acceptor compound is preferably 0.1 parts by mass or more and 20 parts by mass or less with respect to 100 parts by mass of the binder resin contained in the charge transport layer. More preferably, it is 0.5 parts by mass or more and 10 parts by mass or less.

When the photoreceptor is a single layer type photoreceptor, the content of the electron transport agent is 5 parts by mass or more and 100 parts by mass or less with respect to 100 parts by mass of the binder resin contained in the single layer type photosensitive layer. Preferably, it is 10 to 80 parts by mass.

<7. Hole transport agent>
When the photoreceptor is a single layer type photoreceptor, the single layer type photosensitive layer contains, for example, a hole transport agent. When the photoreceptor is a multilayer photoreceptor, the charge transport layer contains, for example, a hole transport agent.

The hole transport agent is not particularly limited as long as it is a hole transport agent for a photoreceptor. Examples of the hole transporting agent include triphenylamine derivatives, diamine derivatives (for example, N, N, N ′, N′-tetraphenylbenzidine derivatives, N, N, N ′, N′-tetraphenylphenylenediamine derivatives, N, N, N ′, N′-tetraphenylnaphthylenediamine derivative, N, N, N ′, N′-tetraphenylphenanthrylenediamine derivative, or di (aminophenylethenyl) benzene derivative), oxadiazole Compounds (eg, 2,5-di (4-methylaminophenyl) -1,3,4-oxadiazole), styryl compounds (eg, 9- (4-diethylaminostyryl) anthracene), carbazole compounds ( For example, polyvinylcarbazole), organic polysilane compounds, pyrazoline compounds (for example, 1-phenyl) 3- (p-dimethylaminophenyl) pyrazoline), hydrazone compounds, indole compounds, oxazole compounds, isoxazole compounds, thiazole compounds, thiadiazole compounds, imidazole compounds, pyrazole compounds or triazole compounds It is done. A hole transport agent may be used individually by 1 type, and may be used in combination of 2 or more type.

An example of the hole transporting agent is a compound represented by the general formula (6).

In the general formula (6), R ₆₁ to R ₆₆ each independently represents a hydrogen atom, an alkyl group, or an alkoxy group. One or more of R ₆₁ , R ₆₂ and R ₆₃ are an alkyl group or an alkoxy group. That is, all of R ₆₁ , R ₆₂ and R ₆₃ do not become hydrogen atoms. One or more of R ₆₄ , R ₆₅ and R ₆₆ are an alkyl group or an alkoxy group. That is, R ₆₄ , R ₆₅ and R ₆₆ are not all hydrogen atoms.

In the general formula (6), each of R ₆₁ to R ₆₆ preferably independently represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms, More preferably, it represents a methyl group or a methoxy group. One or more of R ₆₁ , R ₆₂ and R ₆₃ are preferably an alkyl group having 1 to 6 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms, a methyl group or a methoxy group It is more preferable that One or more of R ₆₄ , R ₆₅ and R ₆₆ are preferably an alkyl group having 1 to 6 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms, a methyl group or a methoxy group It is more preferable that

Specific examples of the compound represented by the general formula (6) include compounds represented by the chemical formulas (H-1) to (H-4). Hereinafter, the compounds represented by the chemical formulas (H-1) to (H-4) may be referred to as compounds (H-1) to (H-4), respectively.

Another example of the hole transporting agent is a compound represented by the general formula (7) or (8).

In the general formulas (7) and (8), R ₆₇ to R ₇₁ each independently represents an alkyl group which may have a substituent selected from the group consisting of an alkoxy group and a halogen atom. In general formula (7), t represents an integer of 0 or more and 2 or less. In general formula (7), u represents 1 or 2.

When the photoreceptor is a multilayer photoreceptor, the content of the hole transport agent is preferably 10 parts by mass or more and 200 parts by mass or less with respect to 100 parts by mass of the binder resin contained in the charge transport layer. More preferably, it is 20 parts by mass or more and 100 parts by mass or less.

When the photoreceptor is a single layer type photoreceptor, the content of the hole transport agent contained in the single layer type photosensitive layer is 10 parts by mass or more and 200 parts by mass or less with respect to 100 parts by mass of the binder resin. Is preferably 10 parts by mass or more and 100 parts by mass or less.

<8. Binder resin>
When the photoreceptor is a single layer type photoreceptor, the single layer type photosensitive layer contains a binder resin. When the photoreceptor is a multilayer photoreceptor, the charge transport layer contains a binder resin.

Examples of the binder resin include a thermoplastic resin, a thermosetting resin, and a photocurable resin. Examples of the thermoplastic resin include polycarbonate resin, polyarylate resin, styrene-butadiene copolymer, styrene-acrylonitrile copolymer, styrene-maleic acid copolymer, acrylic acid polymer, styrene-acrylic acid copolymer, Polyethylene resin, ethylene-vinyl acetate copolymer, chlorinated polyethylene resin, polyvinyl chloride resin, polypropylene resin, ionomer resin, vinyl chloride-vinyl acetate copolymer, alkyd resin, polyamide resin, urethane resin, polysulfone resin, diallyl phthalate Examples of the resin include a ketone resin, a polyvinyl butyral resin, a polyester resin, and a polyether resin. Examples of the thermosetting resin include silicone resin, epoxy resin, phenol resin, urea resin, and melamine resin. Examples of the photocurable resin include epoxy acrylate (epoxy compound acrylic acid adduct) or urethane-acrylate (urethane compound acrylic acid adduct). These binder resins may be used individually by 1 type, and may be used in combination of 2 or more type.

Among these resins, a polycarbonate resin is preferable because a single-layer type photosensitive layer and a charge transport layer having a good balance of workability, mechanical properties, optical properties, and wear resistance can be obtained. Examples of the polycarbonate resin include bisphenol Z type polycarbonate resin, bisphenol ZC type polycarbonate resin, bisphenol C type polycarbonate resin, or bisphenol A type polycarbonate resin having a repeating unit represented by the following chemical formula (R-1).

The viscosity average molecular weight of the binder resin is preferably 20,000 or more, and more preferably 20,000 or more and 52,500 or less. When the viscosity average molecular weight of the binder resin is 20,000 or more, it is easy to improve the abrasion resistance of the photoreceptor. When the viscosity average molecular weight of the binder resin is 52,500 or less, the binder resin is easily dissolved in a solvent during formation of the photosensitive layer, and the viscosity of the charge transport layer coating solution or single layer type photosensitive layer coating solution is increased. Not too much. As a result, it becomes easy to form a charge transport layer or a single-layer type photosensitive layer.

<9. Base resin>
When the photoreceptor is a multilayer photoreceptor, the charge generation layer contains a base resin. The base resin is not particularly limited as long as it is a base resin applicable to the photoreceptor. Examples of the base resin include a thermoplastic resin, a thermosetting resin, and a photocurable resin. Examples of the thermoplastic resin include styrene-butadiene copolymer, styrene-acrylonitrile copolymer, styrene-maleic acid copolymer, styrene-acrylic acid copolymer, acrylic acid polymer, polyethylene resin, and ethylene-vinyl acetate. Copolymer, chlorinated polyethylene resin, polyvinyl chloride resin, polypropylene resin, ionomer, vinyl chloride-vinyl acetate copolymer, alkyd resin, polyamide resin, urethane resin, polycarbonate resin, polyarylate resin, polysulfone resin, diallyl phthalate resin , Ketone resin, polyvinyl butyral resin, polyether resin, or polyester resin. Examples of the thermosetting resin include silicone resins, epoxy resins, phenol resins, urea resins, melamine resins, and other crosslinkable thermosetting resins. Examples of the photocurable resin include epoxy acrylate (epoxy compound acrylic acid adduct) or urethane-acrylate (urethane compound acrylic acid adduct). A base resin may be used individually by 1 type, and may be used in combination of 2 or more type.

The base resin contained in the charge generation layer is preferably different from the binder resin contained in the charge transport layer. In the production of a multilayer photoreceptor, for example, a charge generation layer is formed on a conductive substrate, and a charge transport layer is formed on the charge generation layer. At that time, a charge transport layer coating solution is applied onto the charge generation layer. Therefore, the charge generation layer is preferably not dissolved in the solvent of the charge transport layer coating solution.

<10. Other additives>
The photosensitive layer (charge generation layer, charge transport layer, or single layer type photosensitive layer) of the photoreceptor may contain an additive (other additives) other than the compound (1) as necessary. Other additives include, for example, deterioration inhibitors (for example, antioxidants, radical scavengers, singlet quenchers, or ultraviolet absorbers), softeners, surface modifiers, extenders, thickeners, A dispersion stabilizer, wax, acceptor, donor, surfactant, plasticizer, sensitizer, or leveling agent may be mentioned. Antioxidants include, for example, hindered phenols (eg, di (tert-butyl) p-cresol), hindered amines, paraphenylenediamine, arylalkanes, hydroquinones, spirochromans, spirodanone or derivatives thereof, organic sulfur compounds, Or an organic phosphorus compound is mentioned.

<11. Intermediate layer>
The intermediate layer (undercoat layer) contains, for example, inorganic particles and a resin (intermediate layer resin) used for the intermediate layer. The presence of the intermediate layer is considered to suppress the increase in resistance by smoothing the flow of current generated when the photosensitive member is exposed while maintaining an insulating state capable of suppressing the occurrence of leakage.

As the inorganic particles, for example, metal (for example, aluminum, iron, or copper), metal oxide (for example, titanium oxide, alumina, zirconium oxide, tin oxide, or zinc oxide) particles, or non-metal oxide (for example, , Silica) particles. These inorganic particles may be used individually by 1 type, and may use 2 or more types together.

The intermediate layer resin is not particularly limited as long as it can be used as a resin for forming the intermediate layer. The intermediate layer may contain various additives. Examples of the additive contained in the intermediate layer are the same as those of the additive contained in the photosensitive layer.

<12. Photoconductor manufacturing method>
When the photoreceptor is a multilayer photoreceptor, the multilayer photoreceptor is manufactured, for example, as follows. First, a charge generation layer coating solution and a charge transport layer coating solution are prepared. A charge generation layer is formed by applying a coating solution for charge generation layer onto a conductive substrate and drying. Subsequently, the charge transport layer coating liquid is applied on the charge generation layer and dried to form the charge transport layer. Thereby, a laminated photoreceptor is manufactured.

The coating solution for the charge generation layer is prepared by dissolving or dispersing a charge generation agent and components added as necessary (for example, base resin and other additives) in a solvent. The coating solution for charge transport layer contains compound (1) as an additive, a binder resin, and components added as necessary (for example, a hole transport agent, an electron acceptor compound, and other additives), a solvent It is prepared by dissolving or dispersing in.

Next, when the photoconductor is a single layer type photoconductor, the single layer type photoconductor is manufactured, for example, as follows. The single-layer type photoreceptor is manufactured by applying a coating solution for a single-layer type photosensitive layer onto a conductive substrate and drying it. The coating solution for a single-layer type photosensitive layer is composed of the compound (1) as an additive, a binder resin, and components added as necessary (for example, a charge generator, a hole transport agent, an electron transport agent and other additives) Agent) is dissolved or dispersed in a solvent.

The solvent contained in the coating solution (the coating solution for charge generation layer, the coating solution for charge transport layer, or the coating solution for single-layer type photosensitive layer) is particularly limited as long as each component contained in the coating solution can be dissolved or dispersed. Not. Examples of solvents include alcohols (eg, methanol, ethanol, isopropanol, or butanol), aliphatic hydrocarbons (eg, n-hexane, octane, or cyclohexane), aromatic hydrocarbons (eg, benzene, toluene, or Xylene), halogenated hydrocarbons (eg, dichloromethane, dichloroethane, carbon tetrachloride, or chlorobenzene), ethers (eg, dimethyl ether, diethyl ether, tetrahydrofuran, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, or propylene glycol monomethyl ether), ketones (For example, acetone, methyl ethyl ketone, or cyclohexanone), esters (for example, ethyl acetate or methyl acetate), dimethylformaldehyde Dimethylformamide, or dimethyl sulfoxide. These solvents are used alone or in combination of two or more. In order to improve the workability during the production of the photoreceptor, it is preferable to use a non-halogen solvent (a solvent other than the halogenated hydrocarbon) as the solvent.

The coating solution is prepared by mixing each component and dispersing in a solvent. For mixing or dispersing, for example, a bead mill, a roll mill, a ball mill, an attritor, a paint shaker, or an ultrasonic disperser can be used.

The coating solution (charge generating layer coating solution, charge transport layer coating solution, or single layer photosensitive layer coating solution) may contain, for example, a surfactant in order to improve the dispersibility of each component. Good.

As a method of applying a coating solution (a coating solution for a charge generation layer, a coating solution for a charge transport layer, or a coating solution for a single-layer type photosensitive layer), as long as the coating solution can be uniformly applied on a conductive substrate. There is no particular limitation. Examples of the coating method include a dip coating method, a spray coating method, a spin coating method, and a bar coating method.

The method for drying the coating solution (coating solution for charge generation layer, coating solution for charge transport layer, or coating solution for single-layer type photosensitive layer) is not particularly limited as long as the solvent in the coating solution can be evaporated. For example, the method of heat-processing (hot-air drying) is mentioned using a high-temperature dryer or a vacuum dryer. The heat treatment conditions are, for example, a temperature of 40 ° C. or higher and 150 ° C. or lower and a time of 3 minutes or longer and 120 minutes or shorter.

It should be noted that the method for producing a photoreceptor may further include a step of forming an intermediate layer and / or a step of forming a protective layer, if necessary. A known method is appropriately selected in the step of forming the intermediate layer and the step of forming the protective layer.

The photoreceptor according to this embodiment has been described above. According to the photoconductor of the present embodiment, it is possible to suppress the occurrence of fog in the formed image.

<Second Embodiment: Image Forming Apparatus>
The second embodiment relates to an image forming apparatus. Hereinafter, the image forming apparatus 60 according to the present embodiment will be described with reference to FIGS. 3 and 4.

The image forming apparatus 60 includes a photoreceptor 101 as an image carrier. As described in the first embodiment, the photoconductor 101 can suppress the occurrence of fog in the formed image. Since the image forming apparatus 60 includes such a photoconductor 101, the occurrence of fogging in an image to be formed can be suppressed.

Hereinafter, a case where the image forming apparatus 60 adopts the direct transfer method will be described as an example with reference to FIG. FIG. 3 is a schematic diagram illustrating an example of the configuration of the image forming apparatus 60.

The image forming apparatus 60 includes the photosensitive member 101 described in the first embodiment, the charging unit 27, the exposure unit 28, the developing unit 29, and the transfer unit 26. The charging unit 27 charges the surface of the photoreceptor 101. The exposure unit 28 exposes the charged surface of the photoconductor 101 to form an electrostatic latent image on the surface of the photoconductor 101. The developing unit 29 develops the electrostatic latent image as a toner image. The transfer unit 26 transfers the toner image from the photoconductor 101 to the transfer target 38. When the image forming apparatus 60 adopts the direct transfer method, the transfer unit 26 corresponds to the transfer roller 41. The transfer body 38 corresponds to a recording medium (corresponding to paper) P.

The image forming apparatus 60 is not particularly limited as long as it is an electrophotographic image forming apparatus. The image forming apparatus 60 may be, for example, a monochrome image forming apparatus or a color image forming apparatus. The image forming apparatus 60 may be a tandem color image forming apparatus in order to form toner images of the respective colors using different color toners.

Hereinafter, the image forming apparatus 60 will be described by taking a tandem color image forming apparatus as an example. The image forming apparatus 60 includes a plurality of photoconductors 101 arranged in parallel in a predetermined direction and a plurality of developing units 29. Each of the plurality of developing units 29 is disposed to face the photoconductor 101. The developing unit 29 carries and transports toner, and supplies the toner to the surface of the corresponding photoreceptor 101.

As shown in FIG. 3, the image forming apparatus 60 further includes a box-shaped device housing 70. In the device housing 70, a paper feeding unit 80, an image forming unit 90, and a fixing unit 10 are provided. The paper feed unit 80 feeds the paper P. The image forming unit 90 transfers the toner image based on the image data to the paper P while conveying the paper P fed from the paper feeding unit 80. The fixing unit 10 fixes the unfixed toner image transferred onto the paper P by the image forming unit 90 on the paper P. Further, a paper discharge unit 11 is provided on the upper surface of the device housing 70. The paper discharge unit 11 discharges the paper P fixed by the fixing unit 10.

The paper feed unit 80 includes a paper feed cassette 12, a first pickup roller 13, a plurality of paper feed rollers 14, and a resist roller pair 17. The paper feed cassette 12 is provided so as to be detachable from the device housing 70. Various sizes of paper P are stored in the paper feed cassette 12. The first pickup roller 13 is provided at the upper left position of the paper feed cassette 12. The first pickup roller 13 takes out the sheets P stored in the sheet feeding cassette 12 one by one. The plurality of paper feed rollers 14 transport the paper P picked up by the first pickup roller 13. The registration roller pair 17 temporarily waits for the paper P conveyed by the plurality of paper feed rollers 14 and then supplies the paper P to the image forming unit 90 at a predetermined timing.

Further, the paper feed unit 80 may further include a manual feed tray (not shown) and a second pickup roller 18 (see FIG. 4). The manual feed tray is attached to the left side surface of the device housing 70. The second pickup roller takes out the paper P placed on the manual feed tray. The paper P taken out by the second pickup roller is conveyed by the paper feed roller 14 and is supplied to the image forming unit 90 by the registration roller pair 17 at a predetermined timing.

The image forming unit 90 includes an image forming unit 19 and a transfer belt 40. The image forming unit 19 includes a black toner supply unit 22 and a cyan toner supply unit from the upstream side (left side in FIG. 3) to the downstream side in the rotation direction of the transfer belt 40 with respect to the black toner supply unit 22. 23, a magenta toner supply unit 24, and a yellow toner supply unit 25 are arranged in this order. A photosensitive member 101 is disposed at the center position of each

unit

22, 23, 24, and 25. The photoconductor 101 is arranged to be rotatable in the direction of an arrow (counterclockwise). Around each photoconductor 101, a charging unit 27, an exposure unit 28, a developing unit 29, and a transfer unit 26 are sequentially arranged from the upstream side in the rotation direction of each photoconductor 101 with respect to the charging unit 27. Yes.

One or both of a cleaning device (not shown) and a static eliminator (not shown) may be provided on the upstream side of the charging unit 27 in the rotation direction of the photosensitive member 101. The cleaning device and the static eliminator clean and neutralize the peripheral surface of the photoreceptor 101 after the transfer of the toner image onto the paper P is completed. The peripheral surface of the photoreceptor 101 cleaned and discharged by the cleaning device and the charge eliminator is sent to the charging unit 27 and newly charged. When the image forming apparatus 60 includes a cleaning device and a static eliminator, the charging unit 27, the exposure unit 28, the developing unit 29, the transfer unit 26, and the cleaning device with respect to the charging unit 27 from the upstream side in the rotation direction of each photoconductor 101. , And the static eliminator.

As already described, the charging unit 27 charges the surface (peripheral surface) of the photoreceptor 101. The charging polarity of the charging unit 27 is not particularly limited. When the photoconductor 101 is a single layer type photoconductor provided with a single layer type photoconductive layer 103c (see FIGS. 1A and 1B), in order to improve sensitivity characteristics, the charging unit 27 makes the surface of the photoconductor 101 have a positive polarity. Is preferably charged. When the photoreceptor 101 is a multilayer photoreceptor, the charging unit 27 preferably charges the surface of the photoreceptor 101 to a negative polarity in order to improve sensitivity characteristics.

The charging unit 27 may be a non-contact method or a contact method. The non-contact charging unit 27 applies a voltage without contacting the photoreceptor 101. Examples of the non-contact charging unit 27 include a corona discharge type charging device, and more specifically, a corotron charger or a scorotron charger. The contact-type charging unit 27 is in contact with the photoreceptor 101 and applies a voltage. Examples of the contact-type charging unit 27 include a contact (proximity) discharge type charger, and more specifically, a charging roller or a charging brush. As the charging unit 27, a charging roller is preferable.

Examples of the charging roller include a charging roller that rotates following the rotation of the photoconductor 101 while being in contact with the photoconductor 101. For example, at least a surface portion of the charging roller is formed of a resin. Specifically, the charging roller includes a core metal that is rotatably supported, a resin layer formed on the core metal, and a voltage application unit that applies a voltage to the core metal. The charging unit 27 including such a charging roller charges the surface of the photoreceptor 101 that is in contact via the resin layer when the voltage application unit applies a voltage to the cored bar.

The resin forming the resin layer of the charging roller is not particularly limited as long as the surface of the photoreceptor 101 can be charged satisfactorily. Specific examples of the resin forming the resin layer include a silicone resin, a urethane resin, and a silicone-modified resin. The resin layer may contain an inorganic filler.

When the image forming apparatus 60 includes the contact-type charging unit 27, it is considered that discharge of active gas (for example, ozone or nitrogen oxide) generated from the charging unit 27 can be suppressed. As a result, it is considered that the deterioration of the photosensitive layer 103 due to the active gas is suppressed, and the design considering the office environment can be achieved.

The voltage applied by the charging unit 27 is not particularly limited. Examples of the voltage applied by the charging unit 27 include an AC voltage, a superimposed voltage obtained by superimposing the AC voltage on the DC voltage, or a DC voltage. Especially, it is preferable that the charging unit 27 applies only a DC voltage. The charging unit 27 that applies only a DC voltage has the following advantages compared to the charging unit 27 that applies an AC voltage or the charging unit 27 that applies a superimposed voltage obtained by superimposing an AC voltage on a DC voltage. When the charging unit 27 applies only a DC voltage, the voltage value applied to the photoconductor 101 is constant, so that the surface of the photoconductor 101 is easily charged uniformly to a constant potential. Further, when the charging unit 27 applies only a DC voltage, the wear amount of the photosensitive layer 103 tends to decrease. As a result, it is considered that a suitable image can be formed.

The voltage applied to the photosensitive member 101 by the charging unit 27 is preferably 1000 V or more and 2000 V or less, more preferably 1200 V or more and 1800 V or less, and particularly preferably 1400 V or more and 1600 V or less.

Examples of the exposure unit 28 include an exposure device, and more specifically, a laser scanning unit. The exposure unit 28 exposes the charged surface of the photoconductor 101 to form an electrostatic latent image on the surface of the photoconductor 101. Specifically, the exposure unit 28 irradiates the peripheral surface of the photoconductor 101 charged by the charging unit 27 with laser light based on image data input from a host device such as a personal computer. As a result, an electrostatic latent image based on the image data is formed on the peripheral surface of the photoreceptor 101.

The developing unit 29 develops the electrostatic latent image as a toner image. Specifically, the developing unit 29 supplies toner to the peripheral surface of the photoreceptor 101 on which the electrostatic latent image is formed, and forms a toner image based on the image data. An example of the developing unit 29 is a developing device.

The developing unit 29 can develop the electrostatic latent image as a toner image while being in contact with the photoreceptor 101. That is, the image forming apparatus 60 according to the present embodiment can employ a so-called contact development method.

The developing unit 29 can clean the surface of the photoreceptor 101. That is, the image forming apparatus 60 according to the present embodiment can employ a so-called cleanerless system. The developing unit 29 can remove components remaining on the surface of the photoconductor 101 (hereinafter sometimes referred to as “residual components”). Examples of the residual component include a toner component (more specifically, a toner or a free external additive) or a non-toner component (more specifically, a paper powder).

The image forming apparatus 60 that employs one or both of the contact development method and the cleaner-less method usually frictionally charges the toner due to a difference in peripheral speed between the developing unit 29 (for example, a developing roller) and the photosensitive member 101 during development. Let For this reason, the frictional charging of the toner becomes insufficient, and fog is likely to occur in the formed image. However, the image forming apparatus 60 of the present embodiment includes the photoconductor 101 that can suppress the occurrence of fogging as described above. For this reason, the image forming apparatus 60 according to the present embodiment can suppress the occurrence of fogging in the formed image even if one or both of the contact development method and the cleaner-less method are adopted.

In order for the developing unit 29 to efficiently clean the surface of the photoreceptor 101, it is preferable to satisfy the following conditions (1) and (2).
Condition (1): A contact development method is adopted, and a peripheral speed difference is provided between the photosensitive member 101 and the developing unit 29.
Condition (2): The difference between the absolute value of the surface potential of the photoconductor 101 and the absolute value of the potential of the developing bias satisfies the following formulas (2-1) and (2-2).
0 (V) <absolute value of developing bias potential (V) <absolute value of surface potential of unexposed area of photoreceptor 101 (V) (2-1)
Absolute value of developing bias potential (V)> Absolute value of surface potential of exposed area of photoconductor 101 (V)> 0 (V) (2-2)

When the contact development method shown in condition (1) is adopted and a peripheral speed difference is provided between the photosensitive member 101 and the developing unit 29, the surface of the photosensitive member 101 comes into contact with the developing unit 29, and the photosensitive member 101. Residual components on the surface of the toner are removed by friction with the developing unit 29.

The rotational speed V _P (peripheral speed) of the photoreceptor 101 is preferably 120 mm / second or more and 350 mm / second or less. The rotational speed V _D (peripheral speed) of the developing unit 29 is preferably 133 mm / second or more and 700 mm / second or less. Further, the ratio between the rotational speed V _P of the photoconductor 101 and the rotational speed V _D of the developing unit 29 preferably satisfies the formula (1-1). If the ratio V _P / V _D is other than 1, it indicates that a peripheral speed difference is provided between the photosensitive member 101 and the developing unit 29.
0.5 ≦ V _P / V _D ≦ 0.8 (1-1)

Formula (2-1) of the condition (2) relates to the surface potential of the unexposed area of the photoconductor 101 that has not been exposed by the exposure unit 28. The expression (2-2) of the condition (2) relates to the surface potential of the exposure area of the photoconductor 101 exposed by the exposure unit 28. The surface potential of the unexposed area and the exposed area of the photoconductor 101 are determined by the transfer unit 26 transferring the toner image from the photoconductor 101 to the transfer target 38 and then the charging unit 27 of the next rotation around the photoconductor 101. Measured before charging the surface. When the photoconductor 101 is a single-layer photoconductor, the potential of the developing bias, the surface potential of the unexposed area of the photoconductor 101, and the surface potential of the exposed area of the photoconductor 101 are all positive values, for example. be able to. When the photoconductor 101 is a laminated photoconductor, the potential of the developing bias, the surface potential of the unexposed area of the photoconductor 101, and the surface potential of the exposed area of the photoconductor 101 can all be negative values, for example. .

Regarding the condition (2), when the photosensitive member 101 is a single-layer type photosensitive member, for example, the charging polarity of the toner is positively charged, and the developing method is a reversal developing method. When the photoconductor 101 is a multilayer photoconductor, for example, the toner charging polarity is negatively charged, and the developing method is a reversal developing method. If a difference is provided between the absolute value of the developing bias potential shown in the condition (2) and the absolute value of the surface potential of the photosensitive member 101, the absolute value of the surface potential (charging potential) of the photosensitive member 101 in the unexposed area. Since the value and the absolute value of the potential of the developing bias satisfy the formula (2-1), it acts between the remaining toner (hereinafter, sometimes referred to as “residual toner”) and the unexposed area of the photoreceptor 101. The electrostatic repulsive force is larger than the electrostatic repulsive force acting between the residual toner and the developing unit 29. Therefore, the residual toner in the unexposed area of the photoconductor 101 moves from the surface of the photoconductor 101 to the developing unit 29 and is collected.

If a difference is provided between the absolute value of the developing bias potential and the absolute value of the surface potential of the photoconductor 101 shown in the condition (2), the absolute value of the surface potential (sensitivity potential) of the photoconductor 101 is obtained in the exposure region. Since the absolute value of the potential of the developing bias satisfies Expression (2-2), an electrostatic repulsive force acting between the residual toner and the exposed area of the photosensitive member 101 acts between the toner and the developing unit 29. Smaller than electrostatic repulsion. Therefore, the residual toner in the exposed area of the photoconductor 101 is held on the surface of the photoconductor 101. The toner held in the exposure area of the photoreceptor 101 is used as it is for image formation.

The absolute value of the potential of the developing bias is, for example, 250V or more and 400V or less. The absolute value of the charging potential of the photoconductor 101 is, for example, not less than 450V and not more than 900V. The absolute value of the sensitivity potential of the photoconductor 101 is, for example, 50 V or more and 200 V or less. The difference between the absolute value of the potential of the developing bias and the absolute value of the charging potential of the photoconductor 101 is, for example, 100 V or more and 700 V or less. The difference between the absolute value of the potential of the developing bias and the absolute value of the sensitivity potential of the photosensitive member 101 is, for example, 150 V or more and 300 V or less. Here, the potential difference indicates the absolute value of the difference. When the photoconductor 101 is a single-layer photoconductor, the conditions for providing such a potential difference include, for example, a developing bias potential of +330 V, a charge potential of the photoconductor 101 of +600 V, and a sensitivity of the photoconductor 101. For example, the potential may be set to + 100V.

The transfer unit 26 (corresponding to the transfer roller 41) transfers the toner image formed on the surface of the photoconductor 101 to the transfer target 38 (corresponding to the recording medium, specifically, the paper P). Specifically, the transfer belt 40 is an endless belt-like rotating body. The transfer belt 40 is stretched around a driving roller 30, a driven roller 31, a backup roller 32, and a plurality of transfer rollers 41. The transfer belt 40 is arranged so that the circumferential surface of each photoconductor 101 is in contact with the surface (contact surface) of the transfer belt 40. The transfer belt 40 is pressed against the photoconductor 101 by each transfer roller 41 disposed to face each photoconductor 101. In the pressed state, the transfer belt 40 is rotated endlessly by the plurality of

rollers

30, 31, 32, and 41. The driving roller 30 is rotationally driven by a driving source such as a stepping motor, and gives a driving force for rotating the transfer belt 40 endlessly. The driven roller 31, the backup roller 32, and the transfer roller 41 are rotatably provided. With the endless rotation of the transfer belt 40 by the driving roller 30, the driven roller 31, the backup roller 32, and the plurality of transfer rollers 41 are driven to rotate. These

rollers

31, 32 and 41 are driven to rotate and support the transfer belt 40. The paper P supplied from the registration roller pair 17 is sucked onto the transfer belt 40 by the suction roller 42. The sheet P adsorbed on the transfer belt 40 passes between each photoconductor 101 and the corresponding transfer roller 41 as the transfer belt 40 rotates.

When the transfer roller 41 transfers the toner image from the photoconductor 101 to the paper P, the photoconductor 101 is in contact with the paper P. Specifically, each transfer roller 41 applies a transfer bias (specifically, a bias having a polarity opposite to the toner charging polarity) to the paper P adsorbed on the transfer belt 40. As a result, the toner image formed on the photoconductor 101 is transferred to the paper P between each photoconductor 101 and the corresponding transfer roller 41. The transfer belt 40 circulates in the arrow (clockwise) direction by driving the driving roller 30. Accordingly, the paper P sucked on the transfer belt 40 sequentially passes between each photoconductor 101 and the corresponding transfer roller 41. When passing, the toner images of the corresponding colors formed on the respective photoconductors 101 are sequentially transferred onto the paper P in the overcoated state.

The fixing unit 10 fixes the unfixed toner image transferred to the paper P. The fixing unit 10 includes a heating roller 34 and a pressure roller 35. The heating roller 34 is heated by an energized heating element. The pressure roller 35 is disposed to face the heating roller 34, and the circumferential surface of the pressure roller 35 is pressed against the circumferential surface of the heating roller 34.

The paper P on which the toner image is fixed is transported by a plurality of transport rollers 36 and discharged from the paper discharge unit 11. The paper discharge unit 11 is formed by recessing the top of the device housing 70. A paper discharge tray 37 that receives the discharged paper P is provided at the bottom of the recessed portion. The image forming apparatus 60 that employs the direct transfer method according to one aspect of the present embodiment has been described above with reference to FIG.

Note that the image forming apparatus 60 of this embodiment may adopt an intermediate transfer method. Hereinafter, an image forming apparatus 60 according to another aspect of the present embodiment will be described with reference to FIG. The image forming apparatus 60 shown in FIG. 4 employs an intermediate transfer method. In the image forming apparatus 60 illustrated in FIG. 4, the transfer unit 26 corresponds to the primary transfer roller 33 and the secondary transfer roller 21. The transfer target 38 corresponds to the intermediate transfer belt 20 and the recording medium (corresponding to paper) P. In FIG. 4, elements corresponding to those in FIG. 3 are denoted by the same reference numerals, and redundant description is omitted.

The intermediate transfer belt 20 is an endless belt rotating body. The intermediate transfer belt 20 is stretched around a driving roller 30, a driven roller 31, a backup roller 32, and a plurality of primary transfer rollers 33. The intermediate transfer belt 20 is disposed so that the peripheral surfaces of the plurality of photoconductors 101 are in contact with the surface (contact surface) of the intermediate transfer belt 20.

Further, the intermediate transfer belt 20 is pressed against the photoconductor 101 by the primary transfer roller 33 arranged to face each photoconductor 101. In the pressed state, the intermediate transfer belt 20 rotates endlessly in the arrow (counterclockwise) direction by the drive roller 30. The driving roller 30 is rotationally driven by a driving source such as a stepping motor, and gives a driving force for rotating the intermediate transfer belt 20 endlessly. The driven roller 31, the backup roller 32, and the plurality of primary transfer rollers 33 are rotatably provided. The driven roller 31, the backup roller 32, and the primary transfer roller 33 rotate following the endless rotation of the intermediate transfer belt 20 by the driving roller 30. The driven roller 31, the backup roller 32, and the primary transfer roller 33 are driven to rotate via the intermediate transfer belt 20 according to the main rotation of the driving roller 30 and support the intermediate transfer belt 20.

The primary transfer roller 33 applies a primary transfer bias (specifically, a bias having a polarity opposite to the charging polarity of the toner) to the intermediate transfer belt 20. As a result, the toner image formed on each photoconductor 101 is sequentially transferred (primary transfer) between each photoconductor 101 and the primary transfer roller 33 to the intermediate transfer belt 20 that circulates.

The secondary transfer roller 21 applies a secondary transfer bias (specifically, a bias having a polarity opposite to the charging polarity of the toner) to the paper P. As a result, the toner image primarily transferred onto the intermediate transfer belt 20 is transferred onto the paper P between the secondary transfer roller 21 and the backup roller 32. As a result, an unfixed toner image is transferred onto the paper P.

The unfixed toner image transferred to the paper P by the secondary transfer roller 21 is fixed to the paper P by a fixing process by heating when the paper P passes between the heating roller 34 and the pressure roller 35. Then, the paper P subjected to the fixing process is discharged to the paper discharge unit 11. In addition, a plurality of transport rollers 36 are disposed at appropriate positions between the fixing unit 10 and the paper discharge unit 11.

The image forming apparatus 60 that employs the intermediate transfer method according to another aspect of the present embodiment has been described above with reference to FIG.

As described above with reference to FIGS. 3 and 4, the image forming apparatus 60 according to this embodiment includes the photoconductor 101 according to the first embodiment. The photoreceptor 101 can suppress the occurrence of fogging in the formed image. Therefore, according to the image forming apparatus 60 according to the present embodiment, the occurrence of fogging in the formed image can be suppressed.

<Third embodiment: Process cartridge>
The third embodiment relates to a process cartridge. The process cartridge is an image forming cartridge. Hereinafter, the process cartridge according to the present embodiment will be described with reference to FIGS. 3 and 4. The process cartridge according to the present embodiment corresponds to each of a black toner supply unit 22, a cyan toner supply unit 23, a magenta toner supply unit 24, and a yellow toner supply unit 25. The process cartridge includes, for example, the photoreceptor 101 according to the first embodiment. The photoconductor 101 may be unitized. The process cartridge may be designed to be detachable from the image forming apparatus 60 according to the second embodiment. The process cartridge includes, for example, the charging unit 27, the exposure unit 28, the developing unit 29, and the transfer unit 26 (corresponding to the transfer roller 41 or the primary transfer roller 33) described in the second embodiment in addition to the photosensitive member 101. At least one selected from the group consisting of: The process cartridge may further include one or both of a cleaning device (not shown) and a static eliminator (not shown).

The process cartridge according to the present embodiment has been described above with reference to FIGS. 3 and 4. The process cartridge according to this embodiment includes the photoconductor 101 according to the first embodiment. The photoreceptor 101 can suppress the occurrence of fogging in the formed image. Therefore, according to the process cartridge according to the present embodiment, the occurrence of fogging in the formed image can be suppressed. Furthermore, since such a process cartridge is easy to handle, when the sensitivity characteristic of the photoconductor 101 is deteriorated, the process cartridge including the photoconductor 101 can be easily and quickly replaced.

Hereinafter, the present invention will be described more specifically using examples. However, the present invention is not limited to the scope of the examples.

<1. Material of single layer type photoreceptor>
The following charge generating agent, hole transporting agent, binder resin, electron transporting agent and additive were prepared as materials for forming the single layer type photosensitive layer of the single layer type photoreceptor.

(Charge generator)
Compound (C-1X) was prepared as a charge generator. The compound (C-1X) was a metal-free phthalocyanine represented by the chemical formula (C-1) described in the first embodiment. In addition, the crystal structure of the compound (C-1X) was X type.

(Hole transport agent)
The compound (H-3) described in the first embodiment was prepared as a hole transport agent.

(Binder resin)
Resin (R-1a) was prepared as a binder resin. The resin (R-1a) was a resin having a repeating unit represented by the chemical formula (R-1) described in the first embodiment. In the resin (R-1a), the ratio (molar fraction) of the number of moles of the repeating unit represented by the chemical formula (R-1) to the number of moles of all the repeating units was 100%. The viscosity average molecular weight of the resin (R-1a) was 30000.

(Electron transfer agent)
As the electron transport agent, the compound (E-1) described in the first embodiment was prepared.

(Additive)
As additives, the compounds (A-1), (A-2), (A-4) and (A-5) described in the first embodiment were prepared. As additives, compounds represented by the following chemical formulas (A-3) and (A-6) to (A-10) (hereinafter referred to as compounds (A-3) and (A-6) to (A-10)) ) May also be described).

<2. Manufacture of single layer type photoreceptor>
Single layer type photoreceptors (P-1) to (P-41) were manufactured using the prepared material for forming the photosensitive layer.

<2-1. Manufacture of single layer type photoreceptor (P-2)>
In the container, 2 parts by mass of the compound (C-1X) as a charge generating agent, 50 parts by mass of the compound (H-3) as a hole transporting agent, and 30 parts by weight of the compound (E-1) as an electron transporting agent , 100 parts by mass of the resin (R-1a) as a binder resin, 3 parts by mass of the compound (A-1) as an additive, and 600 parts by mass of tetrahydrofuran as a solvent were added. The content (addition amount) of the compound (A-1) as an additive was 3 parts by mass with respect to 100 parts by mass of the resin (R-1a) as a binder resin. The contents of the container were mixed for 12 hours using a ball mill to disperse the material in the solvent. This obtained the coating liquid for single layer type photosensitive layers. The single-layer photosensitive layer coating solution was applied on a conductive substrate (aluminum base tube) by using a dip coating method. The applied coating liquid for single-layer type photosensitive layer was dried with hot air at 120 ° C. for 80 minutes. As a result, a single-layer type photosensitive layer (thickness 30 μm) was formed on the conductive substrate. As a result, a single layer type photoreceptor (P-2) was obtained.

<2-2. Production of single layer type photoreceptors (P-1) and (P-3) to (P-41)>
Except for the following changes, single-layer photoconductors (P-1) and (P-3) to (P-41) are manufactured in the same manner as the single-layer photoconductor (P-2). did. The compound (A-1) used in the production of the single layer type photoreceptor (P-2) was changed to the type of additive shown in Table 1. The content (addition amount) of 3 parts by mass of the additive with respect to 100 parts by mass of the binder resin in the production of the single layer type photoreceptor (P-2) was changed to the content shown in Table 1.

<3. Evaluation of electrical characteristics>
The electric characteristics of each of the obtained single layer type photoreceptors (P-1) to (P-41) were evaluated. The electrical characteristics were evaluated in an environment having a temperature of 23 ° C. and a humidity of 50% RH (unit of relative humidity). First, the surface of the single-layer type photoreceptor was charged to +600 V using a drum sensitivity tester (manufactured by Gentec Corporation). Next, monochromatic light (wavelength 780 nm, half-value width 20 nm, light energy 1.5 μJ / cm ² ) was extracted from the white light of the halogen lamp using a bandpass filter. The surface of the monolayer type photoreceptor was irradiated with the extracted monochromatic light. The surface potential of the single-layer photoreceptor was measured after 0.5 seconds had elapsed from the end of irradiation. The measured surface potential was defined as the sensitivity potential (V _L , unit + V). Sensitivity potential of the measured single-layer type photoconductor (V _L), and evaluated according to the following evaluation criteria. The smaller the absolute value of the sensitivity potential, the better the electrical characteristics of the single layer type photoreceptor. Tables 1 and 2 show the sensitivity potential (V _L ) and evaluation results of the single layer type photoreceptor.

Evaluation criteria evaluation A of electrical characteristics: Sensitivity potential is less than + 130V.
Evaluation B: The sensitivity potential is + 130V or more and less than + 150V.
Evaluation C: Sensitivity potential is + 150V or more.

<4. Evaluation of fog resistance>
Each of the obtained single-layer type photoreceptors (P-1) to (P-41) was evaluated for fog resistance in the formed image. As an evaluation machine, an image forming apparatus (a modified machine of “monochrome printer FS-1300D” manufactured by Kyocera Document Solutions Inc.) was used. This image forming apparatus employs a contact development method and a cleaner-less method. In this image forming apparatus, the developing unit cleans the toner remaining on the photoreceptor. “Kyocera Document Solutions Brand Paper VM-A4” (A4 size) sold by Kyocera Document Solutions Inc. was used as the paper. A one-component developer (prototype) was used for evaluation by the evaluation machine.

Using an evaluation machine, the image I was continuously printed on 12,000 sheets of paper at a rotational speed of 168 mm / second of a single layer type photoreceptor. Image I was an image with a printing rate of 1%. Subsequently, a blank image was printed on one sheet. Printing was performed in an environment of a temperature of 32.5 ° C. and a humidity of 80% RH. With respect to the obtained blank paper image, the image density at three locations in the blank paper image was measured using a reflection densitometer (“RD914” manufactured by X-rite). The sum of the image densities at three locations on the blank paper image was divided by the number of measurement locations. Thereby, the number average value of the image density of the blank paper image was obtained. The value obtained by subtracting the image density of the base paper from the number average value of the image density of the blank paper image was defined as the fog density. The measured fog density was evaluated according to the following evaluation criteria. A single layer type photoreceptor having an evaluation of A or B was evaluated as having good fog resistance. The fog density (FD) and the evaluation results are shown in Tables 1 and 2.

Fog resistance evaluation standard Evaluation A: The fog density is 0.010 or less.
Evaluation B: The fog density is larger than 0.010 and 0.020 or less.
Evaluation C: The fog density is larger than 0.020.

<5. Overall evaluation>
From the results of the evaluation of the fog resistance of the photoreceptor and the evaluation of the electrical characteristics, the photoreceptor was comprehensively evaluated according to the following evaluation criteria. Tables 1 and 2 show the results of comprehensive evaluation. A photoreceptor having an evaluation of A to D was considered acceptable.

Evaluation standard evaluation A of comprehensive evaluation: Evaluation of fog resistance was A. The evaluation of electrical characteristics was also A.
Evaluation B: The evaluation of fog resistance was A. The evaluation of electrical characteristics was B.
Evaluation C: The evaluation of fog resistance was A. The evaluation of electrical characteristics was C.
Evaluation D: The evaluation of fog resistance was B. The electrical property was evaluated as A, B, or C.
Evaluation E: The evaluation of fog resistance was C. The electrical property was evaluated as A, B, or C.

In Tables 1 and 2, _VL and FD represent the sensitivity potential and the fog density, respectively. In Tables 1 and 2, the additive content indicates the content (addition amount) of the additive with respect to 100 parts by mass of the resin (R-1a) as the binder resin.

The single-layer photosensitive layers of the single-layer photoreceptors (P-2) to (P-29) contained at least a binder resin and an additive. Compound (1) was contained as an additive. Specifically, any of the compounds (A-1), (A-2), (A-4) and (A-5) was contained as an additive. Therefore, as shown in Table 1, the single-layer type photoreceptors (P-2) to (P-29) were evaluated to have a fog resistance of A or B, and were excellent in the fog resistance.

Single-layer type photoreceptors (P-4) to (P-7), (P-11) to (P-14), (P-18) to (P-21) and (P-25) to (P-) In 28), the content of the additive was 10 parts by mass or more and 40 parts by mass or less with respect to 100 parts by mass of the binder resin. Therefore, as shown in Table 1, in these single layer type photoreceptors, the evaluation of fog resistance was A, and the evaluation of electrical characteristics was A or B. Therefore, these photoreceptors have particularly excellent fog resistance and excellent electrical characteristics.

Single-layer type photoreceptors (P-4) to (P-6), (P-11) to (P-13), (P-18) to (P-20) and (P-25) to (P- In 27), the content of the additive was 10 parts by mass or more and 30 parts by mass or less with respect to 100 parts by mass of the binder resin. Therefore, as shown in Table 1, in these single layer type photoreceptors, the evaluation of fog resistance was A, and the evaluation of electrical characteristics was also A. Therefore, these photoreceptors were particularly excellent in fog resistance and electrical characteristics.

The monolayer type photosensitive layer of the monolayer type photoreceptor (P-1) did not contain the compound (1) as an additive. Therefore, as shown in Table 2, the single layer type photoreceptor (P-1) was inferior in fog resistance.

The single-layer photosensitive layers of the single-layer photoreceptors (P-30) to (P-36) contained the compound (A-3) as an additive. The single-layer type photosensitive layers (P-37), (P-38), (P-39), (P-40) and (P-41) each have a compound (A- 6), (A-7), (A-8), (A-9) and (A-10). However, the compounds (A-3), (A-6), (A-7), (A-8), (A-9) and (A-10) are compounds represented by the general formula (1). It wasn't. Therefore, as shown in Table 2, the single layer type photoreceptors (P-30) to (P-41) were inferior in fog resistance.

From the above, it has been shown that the photoreceptor of the present invention can suppress the occurrence of fog in the formed image. Further, it has been shown that the process cartridge and the image forming apparatus of the present invention can suppress the occurrence of fog in the formed image.

The photoconductor according to the present invention can be used, for example, in an image forming apparatus. The process cartridge and the image forming apparatus according to the present invention can be used to form an image on a recording medium, for example.

Claims

An electrophotographic photosensitive member comprising a conductive substrate and a photosensitive layer,
The photosensitive layer contains at least a charge generator, a binder resin and an additive,
The additive is an electrophotographic photoreceptor, which is a compound represented by the following general formula (1).

In the general formula (1), R 1 and R 2 each independently represent an electron withdrawing group, or R 1 represents a hydrogen atom and R 2 represents an electron withdrawing group.
In said general formula (1), R < 1 > and R < 2 > respectively independently represents a halogen atom or a nitro group, or R < 1 > represents a hydrogen atom and R < 2 > represents a halogen atom or a nitro group. Electrophotographic photoreceptor.
The electrophotographic photoreceptor according to claim 1, wherein the content of the additive is 10 parts by mass or more and 40 parts by mass or less with respect to 100 parts by mass of the binder resin.
The electrophotographic photoreceptor according to claim 1, wherein the content of the additive is 10 parts by mass or more and 30 parts by mass or less with respect to 100 parts by mass of the binder resin.
The photosensitive layer includes a charge generation layer containing the charge generation agent, and a charge transport layer containing a hole transport agent, the binder resin and the additive,
The electrophotographic photosensitive member according to claim 1, comprising a single-layer type photosensitive layer containing the charge generating agent, the hole transport agent, the binder resin, an electron transport agent, and the additive as the photosensitive layer.
The electrophotographic photosensitive member according to claim 5, wherein the charge transport layer or the single-layer type photosensitive layer is disposed as an outermost surface layer.
A process cartridge comprising the electrophotographic photosensitive member according to claim 1.
An electrophotographic photoreceptor according to claim 1;
A charging unit for charging the surface of the electrophotographic photosensitive member;
Exposing the surface of the charged electrophotographic photosensitive member to form an electrostatic latent image on the surface of the electrophotographic photosensitive member; and
A developing unit for developing the electrostatic latent image as a toner image;
An image forming apparatus comprising: a transfer unit that transfers the toner image from the electrophotographic photosensitive member to a transfer target.
The image forming apparatus according to claim 8, wherein the developing unit develops the electrostatic latent image as the toner image while being in contact with the electrophotographic photosensitive member.
The image forming apparatus according to claim 8, wherein the developing unit cleans the surface of the electrophotographic photosensitive member.
The transfer object is a recording medium,
The image forming apparatus according to claim 8, wherein the electrophotographic photosensitive member is in contact with the recording medium when the transfer unit transfers the toner image from the electrophotographic photosensitive member to the recording medium.
The image forming apparatus according to claim 8, wherein the charging unit is a charging roller.
As the photosensitive layer, comprising a single-layer type photosensitive layer containing the charge generating agent, hole transport agent, binder resin, electron transport agent and the additive,
The image forming apparatus according to claim 8, wherein the charging unit charges the surface of the electrophotographic photosensitive member to a positive polarity.