CN108139698B

CN108139698B - Electrophotographic photoreceptor, process cartridge, and image forming apparatus

Info

Publication number: CN108139698B
Application number: CN201680057621.0A
Authority: CN
Inventors: 清水智文
Original assignee: Kyocera Document Solutions Inc
Current assignee: Kyocera Document Solutions Inc
Priority date: 2015-10-07
Filing date: 2016-10-05
Publication date: 2021-04-27
Anticipated expiration: 2036-10-05
Also published as: CN108139698A; WO2017061476A1

Abstract

An electrophotographic photoreceptor (101) is provided with a conductive substrate (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 the following general formula (1). In the general formula (1), R₁And R₂Each independently represents an electron withdrawing group, or R₁Represents a hydrogen atom and R₂Represents an electron withdrawing group. In the general formula (1), preferred is: r₁And R₂Each independently represents a halogen atom or a nitro group, or R₁Represents a hydrogen atom and R₂Represents a halogen atom or a nitro group.

Description

Electrophotographic photoreceptor, process cartridge, and image forming apparatus

Technical Field

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

Background

Electrophotographic photoreceptors are used in electrophotographic image forming apparatuses. The electrophotographic photoreceptor includes a photosensitive layer. The photosensitive layer contains, for example, a charge generator, a charge transport agent (for example, a hole transport agent), and a resin (binding resin) that binds them. Examples of the electrophotographic photoreceptor include a laminated electrophotographic photoreceptor and a single-layer electrophotographic photoreceptor. The photosensitive layer in the laminated electrophotographic photoreceptor is a charge generation layer having a charge generation function and a charge transport layer having a charge transport function. The photosensitive layer in the single-layer electrophotographic photoreceptor is a single-layer photosensitive layer having functions of charge generation and charge transport.

For example, a single-layer electrophotographic photoreceptor described in patent document 1 has been studied in order to suppress the generation of fog in a formed image. The single-layer electrophotographic photoreceptor comprises a conductive substrate and a photosensitive layer. The outermost surface layer of the photoreceptor is a photosensitive layer. The photosensitive layer contains a binder resin, and the binder resin is an olefin polymer and at least one of polycarbonate and polyarylate.

[ patent document ]

Patent document 1: japanese patent laid-open publication No. 2011-13365

Disclosure of Invention

However, the electrophotographic photoreceptor described in patent document 1 cannot sufficiently suppress the generation 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 photoreceptor which can suppress the generation of fog in a formed image. Further, an object of the present invention is to provide a process cartridge and an image forming apparatus which can suppress generation of fog in a formed image.

The electrophotographic photoreceptor of the present invention 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 the following general formula (1).

[ CHEM 1 ]

In the general formula (1), R₁And R₂Each independently represents an electron withdrawing group, or R₁Represents a hydrogen atom and R₂Represents an electron withdrawing group.

The process cartridge of the present invention includes the electrophotographic photoreceptor.

An image forming apparatus of the present invention includes: the electrophotographic photoreceptor, the charging section, the exposure section, the developing section, and the transfer section. The charging section charges a surface of the electrophotographic photoreceptor. The exposure section exposes the surface of the charged electrophotographic photoreceptor to form an electrostatic latent image on the surface of the electrophotographic photoreceptor. The developing section develops the electrostatic latent image into a toner image. The transfer section transfers the toner image from the electrophotographic photoreceptor to a transfer object.

[ Effect of the invention ]

According to the present invention, an electrophotographic photoreceptor capable of suppressing the generation of fog in a formed image can be provided. Also, according to the present invention, it is possible to provide a process cartridge and an image forming apparatus which can suppress the generation of fog in a formed image.

Drawings

Fig. 1A is a schematic cross-sectional view of an example of an electrophotographic photoreceptor according to a first embodiment of the present invention.

Fig. 1B is a schematic cross-sectional view of an example of an electrophotographic photoreceptor according to the first embodiment of the present invention.

Fig. 2A is a schematic cross-sectional view of another example of the electrophotographic photoreceptor according to the first embodiment of the present invention.

Fig. 2B is a schematic cross-sectional view of another example of the electrophotographic photoreceptor according to the first embodiment of the present invention.

Fig. 3 is a schematic diagram of an example of the configuration of an image forming apparatus according to a second embodiment of the present invention.

Fig. 4 is a schematic diagram of another example of the configuration of the image forming apparatus according to the second embodiment of the present invention.

Detailed Description

Hereinafter, embodiments of the present invention will be described in detail. However, the present invention is not limited to the following embodiments in any way. The present invention can be implemented with appropriate modifications within the intended scope. Note that, although the description thereof may be omitted as appropriate, the gist of the present invention is not limited thereto.

Hereinafter, the compound and its derivatives may be collectively referred to by adding "class" to the compound name. When a "class" is added to a compound name to indicate a polymer name, the repeating unit indicating the polymer is derived from the compound or a derivative thereof.

Hereinafter, halogen atoms, alkyl groups, alkoxy groups, and aryl groups will be described.

Halogen atoms are, for example: fluorine (fluoro), chlorine (chloro) or bromine (bromo).

Alkyl is, for example, C1-C6 alkyl. The C1-C6 alkyl group is a linear or branched unsubstituted C1-C6 alkyl group. Examples of C1-C6 alkyl groups are: methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, pentyl, isopentyl, neopentyl or hexyl.

Alkoxy is, for example, C1-C6 alkoxy. The C1-C6 alkoxy group is a linear or branched unsubstituted C1-C6 alkoxy group. Examples of C1-C6 alkoxy groups are: methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, sec-butoxy, tert-butoxy, pentoxy, isopentoxy, neopentoxy or hexoxy.

Aryl is, for example, C6-C14 aryl. C6-C14 aryl is, for example: C6-C14 unsubstituted aromatic monocyclic hydrocarbon group, C6-C14 unsubstituted aromatic condensed bicyclic hydrocarbon group or C6-C14 unsubstituted aromatic condensed tricyclic hydrocarbon group. Examples of C6-C14 aryl are: phenyl, naphthyl, anthryl or phenanthryl.

< first embodiment: electrophotographic photoreceptor

The first embodiment relates to an electrophotographic photoreceptor (hereinafter, may be referred to as a photoreceptor). The photoreceptor according to the present embodiment may be a single-layer type photoreceptor or a laminated type 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 photoreceptor of the present embodiment, the generation of fog in the formed image can be suppressed. The reason is presumed as follows. When an image is formed using a photoreceptor and a toner, triboelectrification of the toner may be insufficient. In particular, when an image is formed at a high speed by setting the linear velocity of the photoreceptor to be high, or when an image is continuously formed for a long time, the triboelectrification of the toner is liable to be insufficient. Toner that is insufficiently triboelectrically charged may adhere to a non-exposed portion (portion other than the electrostatic latent image) of the photoreceptor, and an image failure called "fog" may be caused in the formed image.

The photosensitive layer of the photoreceptor of the present embodiment contains the compound (1) as an additive. At least 1 electron-withdrawing group is bonded to 2 para positions of 2 phenyl groups in the compound (1). By containing the compound (1) having such a structure in the photosensitive layer, the difference in the triboelectric series between the photosensitive layer and the toner can be increased. This makes it possible to sufficiently triboelectrically charge the toner when the toner comes into contact with the photosensitive layer. As a result, fogging due to toner (for example, uncharged toner) having insufficient triboelectrification can be suppressed.

The photosensitive layer of the photoreceptor of the present embodiment contains the compound (1) as an additive. When the compound (1) is contained as an additive, the following advantages are expected as compared with the case where an atom having high electronegativity is introduced into a binder resin. First, when a resin having a high electronegativity (for example, polyvinyl chloride) and a polycarbonate resin are used together as a binder resin, it is difficult to uniformly disperse these resins. Therefore, the resin into which atoms having high electronegativity are introduced is sometimes limited to the surface of the photosensitive layer. However, the photosensitive layer of the photoreceptor of the present embodiment contains the compound (1) as an additive. Thereby, the compound (1) tends to be uniformly dispersed in the photosensitive layer. As a result, the photoreceptor according to the present embodiment can easily suppress the generation of fog, particularly when forming an image at a high speed or continuously forming an image for a long time. Second, when a resin (for example, polyvinyl chloride) into which atoms having a high electronegativity are introduced is contained in the photosensitive layer, the resin may block light for exposing the photosensitive layer. However, the compound (1) contained in the photosensitive layer of the photoreceptor of the present embodiment is less likely to block light for exposing the photosensitive layer. As a result, it is considered that the photoreceptor according to the present embodiment can improve electrical characteristics. Thirdly, the compound (1) is a monomer. Therefore, the compound (1) is more likely to enter the gap (void) formed in the photosensitive layer by the binder resin than a resin into which an atom having a high electronegativity is introduced, that is, than a polymer. When the compound (1) enters the cavity to fill the cavity, the oil hardly enters the photosensitive layer. As a result, it is considered that cracking (oil cracking) of the photosensitive layer due to oil adhesion can be suppressed.

<1 > Single layer type photoreceptor

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

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

As shown in fig. 1B, the single-layer photoreceptor 101 may also include a conductive substrate 102, a single-layer photosensitive layer 103c, and an intermediate layer (undercoat layer) 104. The intermediate layer 104 is provided between the conductive substrate 102 and the monolayer photosensitive layer 103c, for example. In addition, a protective layer (not shown) may be provided on the single layer type photosensitive layer 103 c.

The thickness of the monolayer photosensitive layer 103c is not particularly limited as long as the monolayer photosensitive layer can sufficiently exhibit its function. The thickness of the monolayer photosensitive layer 103c is preferably 5 μm to 100 μm, and more preferably 10 μm to 50 μm.

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

<2 > laminated photoreceptor

Hereinafter, a case where the photoreceptor 101 is a laminated photoreceptor will be described with reference to fig. 2A and 2B. Fig. 2A and 2B are schematic cross-sectional views of another example of the photoreceptor 101 according to the present embodiment, that is, a laminated photoreceptor.

As shown in fig. 2A, a laminated photoreceptor as a photoreceptor 101 includes a conductive substrate 102 and a photosensitive layer 103. The layered photoreceptor 101 includes a charge generation layer 103a and a charge transport layer 103b, and the charge generation layer 103a and the charge transport layer 103b serve as a photosensitive layer 103.

As shown in fig. 2A, the photosensitive layer 103 may be directly provided 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. In addition, a protective layer (not shown) may be provided on the photosensitive layer 103.

The thicknesses of the charge generation layer 103a and the charge transport layer 103b are not particularly limited as long as each layer can sufficiently exhibit its function. The thickness of the charge generation layer 103a is preferably 0.01 μm to 5 μm, and more preferably 0.1 μm to 3 μm. The thickness of the charge transport layer 103b is preferably 2 μm to 100 μm, and more preferably 5 μm to 50 μm.

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

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

In order to suppress the generation of fog in the formed image in particular, the photosensitive layer 103 containing the compound (1) is preferably disposed as the outermost surface layer of the photoreceptor 101. Specifically, the single-layer photosensitive layer 103c or the charge transport layer 103b containing the compound (1) is preferably disposed as the outermost surface layer of the photoreceptor 101. The reason for this is that by containing the compound (1) in the outermost surface layer, the difference in the triboelectric charging sequence between the outermost surface layer contacting the toner and the toner can be increased. As a result, as described above, fogging due to toner (for example, uncharged toner) having insufficient triboelectrification can be suppressed.

The structures of the single-layer type photoreceptor and the laminated type photoreceptor as the photoreceptor are described above with reference to fig. 1A, 1B, 2A, and 2B. Next, common elements of the single-layer type photoreceptor and the laminated 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 a conductive substrate of a photoreceptor. In the conductive substrate, at least the surface portion may be formed of a conductive material. Examples of the conductive substrate are: a conductive substrate formed of a conductive material. Examples of the conductive substrate are: 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, or brass. One of these conductive materials may be used alone, or two or more of them may be used in combination (for example, as an alloy). Among these conductive materials, aluminum or an aluminum alloy is preferable in terms of good charge transfer from the photosensitive layer to the conductive substrate.

The shape of the conductive substrate is appropriately selected according to the configuration of the image forming apparatus described later in the second embodiment. The conductive substrate has a sheet-like or drum-like shape, for example. The thickness of the conductive substrate is appropriately selected according to the shape of the conductive substrate.

<4. Charge generating agent >

In the case where the photoreceptor is a single-layer type photoreceptor, the single-layer type photosensitive layer contains, for example, a charge generator. In the case where the photoreceptor is a laminated photoreceptor, the charge generating layer contains, for example, a charge generating agent.

The charge generating agent is not particularly limited as long as it is a charge generating agent for a photoreceptor. Examples of the charge generating agent include: phthalocyanine pigments, dithioketopyrrolopyrrole (dithioketopyrrolidine) pigments, metal-free naphthalocyanine pigments, metal naphthalocyanine pigments, squarylium pigments, indigo pigments, azulene pigments, cyanine pigments, powders of inorganic photoconductive materials (e.g., selenium-tellurium, selenium-arsenic, cadmium sulfide, or amorphous silicon), pyranium salts, anthanthroquinone pigments, triphenylmethane pigments, threne pigments, toluidine pigments, pyrazoline pigments, or quinacridone pigments.

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

[ CHEM 2 ]

[ CHEM 3 ]

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

The charge generating agent having an absorption wavelength in a desired region may be used alone, or 2 or more kinds of charge generating agents may be used in combination. For example, in a digital optical image forming apparatus (for example, a laser printer or a facsimile machine using a light source such as a semiconductor laser), a photoreceptor having sensitivity in a wavelength region of 700nm or more is preferably used. Therefore, for example, phthalocyanine pigments are preferable, metal-free phthalocyanines or oxytitanium phthalocyanines are more preferable, and X-type metal-free phthalocyanines are particularly preferable. One kind of charge generating agent may be used alone, or two or more kinds may be used in combination.

For photoreceptors used in image forming apparatuses using short-wavelength laser light sources (for example, laser light sources having a wavelength in the range of 350nm to 550 nm), it is preferable to use an anthraquinone-based pigment as the charge generating agent.

When the photoreceptor is a laminated photoreceptor, the content of the charge generating agent is preferably 5 parts by mass or more and 1000 parts by mass or less, and more preferably 30 parts by mass or more and 500 parts by mass or less, with respect to 100 parts by mass of the matrix resin contained in the charge generating layer.

When the photoreceptor is a single-layer photoreceptor, the content of the charge generating agent is preferably 0.1 to 50 parts by mass, more preferably 0.5 to 30 parts by mass, based on 100 parts by mass of the binder resin contained in the single-layer photosensitive layer.

<5 > Compound (1)

When the photoreceptor is a single-layer photoreceptor, the single-layer photosensitive layer as the photosensitive layer contains the compound (1) as an additive. In the case where 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), as described above, the generation of fog in the formed image can be suppressed.

The compound (1) is represented by the following general formula (1).

[ CHEM 4 ]

In the general formula (1), R₁And R₂Each independently represents an electron withdrawing group, or R₁Represents a hydrogen atom and R₂Represents an electron withdrawing group. R₁And R₂Not all hydrogen atoms. At R₁And R₂Each independently represents an electron-withdrawing group, R₁And R₂The electron-withdrawing groups may be the same kind as each other or different kinds of electron-withdrawing groups.

The definition and examples of the electron-withdrawing group are as described in "first edition of chemical dictionary" by kyo chemical co-pending by imperial society of china, ltd. Specifically, electron withdrawing groups refer to: compared with a hydrogen atom, it is easy to attract electrons to the bonded atom side (R in the general formula (1))₁And R₂Pendant) groups. An electron withdrawing group is, for example, a group having a positive substituent constant. Examples of the electron-withdrawing group include: halogen atom, -NO₂(nitro), -CN (cyano), -CF₃(trifluoromethyl), -CCl₃(trichloromethyl), -CHO (formyl), -CO-CH₃(acetyl), -CO-OC₂H₅(ethoxycarbonyl), -COOH (carboxyl), -SO₂CH₃(methylsulfonyl) or-SO₃H (sulfonic acid group).

In addition, the groups shown below are electron donating groups. For example, -OH (hydroxy), -OCH₃(methoxy), -O-CO-CH₃(methylcarbonyloxy), -NH₂(amino), -N (CH)₃)₂(dimethylamino), -N (CH)₂CH₃)₂(diethylamino), -NH-CO-CH₃(methylcarbamoyl), alkyl, and aryl are electron donating groups. The electron donating group is: a group in which an electron is easily given on the side of the bonded atom as compared with a hydrogen atom. Electron-donating groups are, for example, groups having a negative substituent constant. Definition and examples of electron donating groups are "chemical dictionary" of the same chemical company of Beijing, imperial envoy, IncThe first edition of the dictionary ".

In the general formula (1), R is preferably used for suppressing the generation of fog in the formed image₁And R₂Each independently represents a halogen atom or a nitro group, or preferably R₁Represents a hydrogen atom and R₂Represents a halogen atom or a nitro group.

In a more preferred example for suppressing the generation of fog in the formed image, R in the general formula (1)₁And R₂Each independently represents a halogen atom. "each independently represents a halogen atom" means: for example R₁Is fluoro radical, R₂Is a chloro group. In order to suppress the generation of fog in the formed image, it is particularly preferable that: r is represented by the following chemical formula (A-1)₁And R₂Both represent a chlorine group. Hereinafter, the compound represented by the formula (A-1) may be referred to as a compound (A-1).

[ CHEM 5 ]

In another more preferable example for suppressing the generation of fog in the formed image, R in the general formula (1)₁Represents a hydrogen atom and R₂Represents a halogen atom. In order to suppress the generation of fog in the formed image, it is particularly preferable that: r is represented by the following chemical formula (A-2)₁Represents a hydrogen atom and R₂Represents a chlorine group. Hereinafter, the compound represented by the formula (A-2) may be referred to as a compound (A-2).

[ CHEM 6 ]

In another more preferable example for suppressing the generation of fog in the formed image, R in the general formula (1)₁And R₂Both represent nitro groups. At R₁And R₂When both represent a nitro group, the compound (1) is represented by the following chemical formula (A-4). A compound represented by the following chemical formula (A-4)The compound (A) may be referred to as a compound (A-4).

[ CHEM 7 ]

In another more preferable example for suppressing the generation of fog in the formed image, R in the general formula (1)₁Represents a hydrogen atom and R₂Represents a nitro group. At R₁Represents a hydrogen atom and R₂When a nitro group is represented, the compound (1) is represented by the following chemical formula (A-5). Hereinafter, the compound represented by the formula (A-5) may be referred to as a compound (A-5).

[ CHEM 8 ]

When the photoreceptor is a single-layer photoreceptor, the content of the compound (1) as an additive is preferably 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 single-layer photosensitive layer. When the photoreceptor is a multilayer photoreceptor, the content of the compound (1) as an additive is preferably 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. When the content of the compound (1) is 10 to 40 parts by mass, the generation of fog in a formed image can be particularly suppressed, and the electrical characteristics of the photoreceptor can be improved.

When the photoreceptor is a single-layer photoreceptor, the content of the compound (1) as an additive is more preferably 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 single-layer photosensitive layer. When the photoreceptor is a multilayer photoreceptor, the content of the compound (1) as an additive is more preferably 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. When the content of the compound (1) is 10 parts by mass or more, the generation 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 transport agent and Electron acceptor Compound >

When the photoreceptor is a single-layer photoreceptor, the single-layer photosensitive layer may contain an electron-transporting agent as needed. This allows the monolayer type photosensitive layer to transmit electrons, and the monolayer type photosensitive layer can easily have bipolar (bipolar) characteristics. When the photoreceptor is a laminated photoreceptor, the charge transport layer may contain an electron acceptor compound as needed. This makes it easy to improve the hole transporting performance of the hole transporting agent.

Examples of electron transport agents or electron acceptor compounds are: quinone compounds, imide 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 the quinone compound include: a diphenoquinone compound, an azoquinone compound, an anthraquinone compound, a naphthoquinone compound, a nitroanthraquinone compound or a dinitroanthraquinone compound. The electron-transporting agent may be used alone or in combination of two or more. Similarly, one kind of the electron acceptor compound may be used alone, or two or more kinds may be used in combination.

Specific examples of electron transport agents are: a compound represented by the general formula (2). In order to suppress the generation of fog in the formed image, the compound represented by the general formula (2) is preferable.

[ CHEM 9 ]

In the general formula (2), R₂₁And R₂₂Each independently represents a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxy group, or a substituted or unsubstituted aryl group. At R₂₁And R₂₂In the case of an alkyl group having a substituent, the substituent is selected from the group consisting of an alkoxy group and a halogen atom. At R₂₁And R₂₂In the case of an alkoxy group having a substituent, the substituent is selected from the group consisting of an alkoxy group and a halogen atom. At R₂₁And R₂₂In the case of 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.

R₂₁And R₂₂Each independently is preferably an alkyl group or an alkoxy group, more preferably an alkyl group.

At R₂₁And R₂₂When the alkyl group is used, the alkyl group is preferably a C1-C6 alkyl group, more preferably a C1-C4 alkyl group, and still more preferably a C1-C2 alkyl group.

R₂₁And R₂₂Preferably different from each other. For example, it may be: r₂₁Is alkyl, R₂₂Is an alkoxy group. For example, at R₂₁And R₂₂In the case of both alkyl groups, this may be: r₂₁Is methyl, R₂₂Is ethyl.

In the general formula (2), R₂₃、R₂₄And R₂₅Each independently represents a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxy group, or a substituted or unsubstituted aryl group. At R₂₃、R₂₄And R₂₅In the case of an alkyl group having a substituent, the substituent is selected from the group consisting of an alkoxy group and a halogen atom. At R₂₃、R₂₄And R₂₅In the case of an alkoxy group having a substituent, the substituent is selected from the group consisting of an alkoxy group and a halogen atom. At R₂₃、R₂₄And R₂₅In the case of 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. R₂₃、R₂₄And R₂₅Preferably represents a hydrogen atom.

R₂₆And R₂₇Each independently represents a hydrogen atom, an alkyl group, an alkoxy group or a halogen atom. R₂₆And R₂₇Preferably represents a hydrogen atom.

For improving the photoreceptorPreferably R in the general formula (2) in the electrical characteristics and the suppression of the generation of fog in the formed image₂₁～R₂₇The following groups are shown. R₂₁And R₂₂Each independently represents a C1-C6 alkyl group. R₂₃、R₂₄And R₂₅Represents a hydrogen atom. R₂₆And R₂₇Represents a hydrogen atom.

Examples of the compound (2) are: n, N ' -bis (2-methyl-6-ethylphenyl) naphthalene-1, 4, 5, 8-tetracarboxylic acid diimide (a compound represented by the formula (E-1), hereinafter sometimes referred to as "compound (E-1)"), N ' -bis (2-ethyl-6-methylphenyl) naphthalene-1, 4, 5, 8-tetracarboxylic acid diimide, N ' -bis (2, 4-dimethyl-6-ethylphenyl) naphthalene-1, 4, 5, 8-tetracarboxylic acid diimide, N ' -bis (2-methyl-6-ethoxyphenyl) naphthalene-1, 4, 5, 8-tetracarboxylic acid diimide, N ' -bis (2-methyl-6-methoxyphenyl) naphthalene-1, 4, 5, 8-tetracarboxylic acid diimide or N, N' -bis (2-methyl-6-methoxyethylphenyl) naphthalene-1, 4, 5, 8-tetracarboxylic acid diimide.

[ CHEM 10 ]

Other specific examples of electron transport agents are: a compound represented by the general formula (3), (4) or (5).

[ CHEM 11 ]

[ CHEM 12 ]

[ CHEM 13 ]

In the general formulae (3), (4) and (5), R₂₈～R₃₅Each independently represents a hydrogen atom, a cyano group, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted alkoxycarbonyl group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted heterocyclic group. In the general formula (5), R₃₆Each independently represents a hydrogen atom, a halogen atom, a cyano group, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted alkoxycarbonyl group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted heterocyclic group.

In the general formulae (3), (4) and (5), R₂₈～R₃₆The alkyl radicals indicated are preferably C1-C6 alkyl radicals, more preferably C1-C5 alkyl radicals, and in particular methyl, 1-dimethylpropyl or tert-butyl radicals. The alkyl group may have a substituent. Examples of the substituents are: a halogen atom, a hydroxyl group, a C1-C6 alkoxy group, a C6-C14 aryl group which may further have a substituent, or a cyano group. The number of the substituents is not particularly limited, but is preferably 3 or less. The substituent(s) of the C6-C14 aryl group further includes, for example: halogen atom, hydroxyl group, C1-C6 alkyl group, C1-C6 alkoxy group, nitro group, cyano group, C2-C7 alkanoyl group (group having C1-C6 alkyl group bonded to carbonyl group), benzoyl group, phenoxy group, C2-C7 alkoxycarbonyl group (group having C1-C6 alkoxy group bonded to carbonyl group), or phenoxycarbonyl group.

In the general formulae (3), (4) and (5), R₂₈～R₃₆Examples of the alkenyl group include straight-chain or branched unsubstituted C2-C6 alkenyl groups. The C2-C6 alkenyl group has, for example, 1 or more and 3 or less double bonds. Examples of C2-C6 alkenyl are: ethenyl, propenyl, butenyl, pentenyl, pentadienyl, hexenyl, or hexadienyl. The alkenyl group may have a substituent. Examples of the substituents are: halogen atom, hydroxyl, C1-C6 alkoxy, C6-C14 aryl or cyano. The number of the substituents is not particularly limited, but is preferably 3 or less.

In the general formulae (3), (4) and (5), R₂₈～R₃₆The alkoxy group is preferably a C1-C6 alkoxy group, more preferably a C1-C3 alkoxy groupMethoxy is particularly preferred. The alkoxy group may have a substituent. Examples of the substituents are: halogen atom, hydroxyl, C1-C6 alkoxy, C6-C14 aryl or cyano. The substituent is preferably phenyl. The number of the substituents is not particularly limited, but is preferably 3 or less, and more preferably 1.

In the general formulae (3), (4) and (5), R₂₈～R₃₆Alkoxycarbonyl groups shown are, for example, C2-C7 alkoxycarbonyl groups. The C2-C7 alkoxycarbonyl group is a group in which a linear or branched unsubstituted C1-C6 alkoxy group is bonded to a carbonyl group. The alkoxycarbonyl group may have a substituent. Examples of the substituents are: halogen atom, hydroxyl, C1-C6 alkoxy, C6-C14 aryl or cyano. The number of the substituents is not particularly limited, but is preferably 3 or less.

In the general formulae (3), (4) and (5), R₂₈～R₃₆The aryl group shown is preferably a C6-C14 aryl group, more preferably a phenyl group. The aryl group may have a substituent. Examples of the substituents are: halogen atom, hydroxyl group, C1-C6 alkyl group, C1-C6 alkoxy group, nitro group, cyano group, C2-C7 alkanoyl group (group having C1-C6 alkyl group bonded to carbonyl group), benzoyl group, phenoxy group, C2-C7 alkoxycarbonyl group (group having C1-C6 alkoxy group bonded to carbonyl group), phenoxycarbonyl group, C6-C14 aryl group, or biphenyl group. The number of the substituents is not particularly limited, but is preferably 3 or less.

In the general formulae (3), (4) and (5), R₂₈～R₃₆The heterocyclic group shown is, for example, a 5-or 6-membered monocyclic heterocyclic group containing 1 or more heteroatoms selected from the group consisting of N, S and O; a heterocyclic group in which the above-mentioned monocyclic rings are condensed with each other; or a heterocyclic group obtained by condensing the above monocyclic ring with a 5-or 6-membered hydrocarbon ring. In the case where the heterocyclic group is a fused ring, the number of rings contained in the fused ring is preferably 3 or less. The heterocyclic group may have substituents such as: halogen atom, hydroxyl group, C1-C6 alkyl group, C1-C6 alkoxy group, nitro group, cyano group, C2-C7 alkanoyl group (group having C1-C6 alkyl group bonded to carbonyl group), benzoyl group, phenoxy group, C2-C7 alkoxycarbonyl group (group having C1-C6 alkoxy group bonded to carbonyl group), or phenoxycarbonyl group. The number of the 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 to 20 parts by mass, more preferably 0.5 to 10 parts by mass, based on 100 parts by mass of the binder resin contained in the charge transport layer.

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

<7 > hole-transporting agent >

In the case where the photoreceptor is a single-layer type photoreceptor, the single-layer type photosensitive layer contains, for example, a hole transporting agent. In the case where the photoreceptor is a laminated photoreceptor, the charge transport layer contains, for example, a hole transport agent.

The hole-transporting agent is not particularly limited as long as it is a hole-transporting agent for photoreceptors. Examples of the hole-transporting agent include: triphenylamine derivatives, diamine derivatives (e.g., N ' -tetraphenylbenzidine derivatives, N ' -tetraphenylphenylenediamine derivatives, N ' -tetraphenylnaphthylenediamine derivatives, N ' -tetraphenylphenylenediamine (N, N ' -tetraphenylphenylenediamine) derivatives or bis (aminophenylvinyl) benzene derivatives), oxadiazole compounds (e.g., 2, 5-bis (4-methylaminophenyl) -1, 3, 4-oxadiazole), styrene compounds (e.g., 9- (4-diethylaminostyryl) anthracene), carbazole compounds (e.g., polyvinylcarbazole), organopolysiloxane compounds, pyrazoline compounds (e.g., 1-phenyl-3- (p-dimethylaminophenyl) pyrazoline), A hydrazone compound, an indole compound, an oxazole compound, an isoxazole compound, a thiazole compound, a thiadiazole compound, an imidazole compound, a pyrazole compound or a triazole compound. The hole-transporting agent may be used alone or in combination of two or more.

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

[ CHEM 14 ]

In the general formula (6), R₆₁～R₆₆Each independently represents a hydrogen atom, an alkyl group or an alkoxy group. R₆₁、R₆₂And R₆₃1 or more of (A) are alkyl groups or alkoxy groups. That is, R₆₁、R₆₂And R₆₃Not all hydrogen atoms. R₆₄、R₆₅And R₆₆1 or more of (A) are alkyl groups or alkoxy groups. That is, R₆₄、R₆₅And R₆₆Not all hydrogen atoms.

In the general formula (6), R₆₁～R₆₆Each independently preferably represents a hydrogen atom, a C1-C6 alkyl group or a C1-C6 alkoxy group, more preferably a methyl group or a methoxy group. Preferably R₆₁、R₆₂And R₆₃1 or more of (A) are C1-C6 alkyl groups or C1-C6 alkoxy groups, more preferably methyl groups or methoxy groups. Preferably R₆₄、R₆₅And R₆₆1 or more of (A) are C1-C6 alkyl groups or C1-C6 alkoxy groups, more preferably methyl groups or methoxy groups.

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.

[ CHEM 15 ]

[ CHEM 16 ]

[ CHEM 17 ]

[ CHEM 18 ]

Other examples of the hole-transporting agent include compounds represented by the general formula (7) or (8).

[ CHEM 19 ]

[ CHEM 20 ]

In the general formulae (7) and (8), R₆₇～R₇₁Each independently represents an alkyl group which may have a substituent selected from the group consisting of an alkoxy group and a halogen atom. In the general formula (7), t represents an integer of 0 to 2. In the general formula (7), u represents 1 or 2.

When the photoreceptor is a multilayer photoreceptor, the content of the hole transporting agent is preferably 10 parts by mass or more and 200 parts by mass or less, and more preferably 20 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 charge transporting layer.

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

<8. Binder resin >

When the photoreceptor is a single-layer photoreceptor, the single-layer photosensitive layer contains a binder resin. In the case where the photoreceptor is a laminated photoreceptor, the charge transport layer contains a binder resin.

Examples of the binder resin include: a thermoplastic resin, a thermosetting resin, or a photocurable resin. Examples of the thermoplastic resin include: polycarbonate resin, polyarylate resin, styrene-butadiene copolymer, styrene-acrylonitrile copolymer, styrene-maleic acid copolymer, acrylic 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, polyurethane resin, polysulfone resin, diallyl phthalate resin, ketone resin, polyvinyl butyral resin, polyester resin, or polyether resin. Examples of the thermosetting resin include: silicone resin, epoxy resin, phenol resin, urea resin, or melamine resin. Examples of the photocurable resin include: epoxy acrylates (acrylic acid adducts of epoxy compounds) or polyurethane-acrylates (acrylic acid adducts of polyurethane compounds). These binder resins may be used alone or in combination of two or more.

Among these resins, polycarbonate resins are preferred from the viewpoint of obtaining a monolayer type photosensitive layer and a charge transport layer which are excellent in balance among processability, mechanical properties, optical properties and abrasion resistance. Examples of the polycarbonate resin are: a bisphenol Z type polycarbonate resin, a bisphenol ZC type polycarbonate resin, a bisphenol C type polycarbonate resin or a bisphenol A type polycarbonate resin having a repeating unit represented by the following chemical formula (R-1).

[ CHEM 21 ]

The viscosity average molecular weight of the binder resin is preferably 20,000 or more, 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, the abrasion resistance of the photoreceptor is easily improved. When the viscosity average molecular weight of the binder resin is 52,500 or less, the binder resin is easily dissolved in a solvent at the time of forming the photosensitive layer, and the viscosity of the coating liquid for the charge transport layer or the coating liquid for the single layer type photosensitive layer does not become too high. As a result, the charge transport layer or the single layer type photosensitive layer is easily formed.

<9. base resin >

When the photoreceptor is a laminated photoreceptor, the charge generation layer contains a matrix resin. The base resin is not particularly limited as long as it is a base resin applicable to a photoreceptor. Examples of the matrix resin include: a thermoplastic resin, a thermosetting resin, or 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, ethylene-vinyl acetate copolymer, chlorinated polyethylene resin, polyvinyl chloride resin, polypropylene resin, ionomer, vinyl chloride-vinyl acetate copolymer, alkyd resin, polyamide resin, polyurethane 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, phenolic resins, urea-formaldehyde resins, melamine resins, or other cross-linking thermosetting resins. Examples of the photocurable resin include: epoxy acrylates (acrylic acid adducts of epoxy compounds) or polyurethane-acrylates (acrylic acid adducts of polyurethane compounds). The base resin may be used alone in 1 kind, or two or more kinds may be used in combination.

The matrix resin contained in the charge generating layer is preferably different from the binder resin contained in the charge transporting layer. The reason is as follows: in the production of a laminated photoreceptor, for example, a charge generation layer is formed on a conductive substrate, a charge transport layer is formed on the charge generation layer, and a coating liquid for the charge transport layer is applied to the charge generation layer in the process. Therefore, the charge generating layer is preferably a solvent that is insoluble in the coating liquid for charge transporting layer.

<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 additive) other than the compound (1) as needed. Other additives are for example: degradation inhibitors (e.g., antioxidants, radical scavengers, singlet quenchers, or ultraviolet absorbers), softening agents, surface modifiers, extenders, thickeners, dispersion stabilizers, waxes, acceptors, donors, surfactants, plasticizers, sensitizers, or leveling agents. Examples of the antioxidant include: hindered phenols (e.g., di-t-butyl-p-cresol), hindered amines, p-phenylenediamine, arylalkanes, hydroquinones, spirochromans (spirochromans), spiroindanones (spiroindanones), or derivatives thereof; organic sulfur compounds or organic phosphorus compounds.

<11. intermediate layer >

The intermediate layer (undercoat layer) contains, for example, inorganic particles and a resin (resin for intermediate layer) used in the intermediate layer. It can be considered that: the presence of the intermediate layer allows smooth current flow to be generated when the photoreceptor is exposed, while maintaining an insulating state to such an extent that leakage current can be suppressed, thereby suppressing an increase in resistance.

Examples of the inorganic particles include: particles of a metal (e.g., aluminum, iron, or copper), a metal oxide (e.g., titanium dioxide, aluminum oxide, zirconium oxide, tin oxide, or zinc oxide), or a non-metal oxide (e.g., silicon dioxide). These inorganic particles may be used alone or in combination of 2 or more.

The resin for the intermediate layer is not particularly limited as long as it can be used as a resin for forming the intermediate layer. The intermediate layer may also 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 > method for producing photoreceptor

For example, when the photoreceptor is a laminated photoreceptor, the laminated photoreceptor is manufactured as follows. First, a coating liquid for a charge generating layer and a coating liquid for a charge transporting layer are prepared. The charge generation layer is formed by applying a coating liquid for a charge generation layer on a conductive substrate and drying the coating liquid. Next, a charge transport layer is formed by applying a charge transport layer coating solution on the charge generation layer and drying the coating solution. In this way, a laminated photoreceptor was produced.

The coating liquid for a charge generating layer is prepared by dissolving or dispersing a charge generating agent and components (for example, a matrix resin and other additives) added as needed in a solvent. The coating liquid for a charge transporting layer is prepared by dissolving or dispersing the compound (1) as an additive, a binder resin, and components added as needed (for example, a hole transporting agent, an electron acceptor compound, and other additives) in a solvent.

Next, for example, in the case where the photoreceptor is a single-layer type photoreceptor, the single-layer type photoreceptor is manufactured as follows. The single-layer photosensitive layer coating liquid is coated on a conductive substrate and dried to produce a single-layer photoreceptor. The coating liquid for a monolayer type photosensitive layer is produced by dissolving or dispersing the compound (1) as an additive, a binder resin, and components added as needed (for example, a charge generating agent, a hole transporting agent, an electron transporting agent, and other additives) in a solvent.

The solvent contained in the coating liquid (coating liquid for a charge generating layer, coating liquid for a charge transporting layer, or coating liquid for a single-layer photosensitive layer) is not particularly limited as long as it can dissolve or disperse each component contained in the coating liquid. Examples of solvents are: alcohols (e.g., methanol, ethanol, isopropanol, or butanol), aliphatic hydrocarbons (e.g., n-hexane, octane, or cyclohexane), aromatic hydrocarbons (e.g., benzene, toluene, or xylene), halogenated hydrocarbons (e.g., dichloromethane, dichloroethane, carbon tetrachloride, or chlorobenzene), ethers (e.g., dimethyl ether, diethyl ether, tetrahydrofuran, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, or propylene glycol monomethyl ether), ketones (e.g., acetone, methyl ethyl ketone, or cyclohexanone), esters (e.g., ethyl acetate or methyl acetate), dimethyl formaldehyde, dimethyl formamide, or dimethyl sulfoxide. These solvents may be used alone or in combination of two or more. In order to improve the workability in manufacturing the photoreceptor, the solvent is preferably a non-halogenated solvent (a solvent other than halogenated hydrocarbon).

A coating liquid was prepared by mixing and dispersing the respective components in a solvent. For the operation of 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 liquid (coating liquid for charge generation layer, coating liquid for charge transport layer, or coating liquid for single layer type photosensitive layer) may contain, for example, a surfactant in order to improve dispersibility of each component.

The method of coating with the coating liquid (coating liquid for a charge generation layer, coating liquid for a charge transport layer, or coating liquid for a single layer type photosensitive layer) is not particularly limited as long as the coating liquid can be uniformly applied to the conductive substrate. Examples of the coating method include: dip coating, spray coating, spin coating or bar coating.

The method for drying the coating liquid (coating liquid for charge generating layer, coating liquid for charge transporting layer, or coating liquid for single-layer photosensitive layer) is not particularly limited as long as the solvent in the coating liquid can be evaporated. For example, a method of performing heat treatment (hot air drying) using a high-temperature dryer or a reduced-pressure dryer. The heat treatment conditions are, for example, a temperature of 40 ℃ to 150 ℃ and a time of 3 minutes to 120 minutes.

The method for manufacturing the photoreceptor may further include a step of forming an intermediate layer and/or a step of forming a protective layer, as necessary. In the step of forming the intermediate layer and the step of forming the protective layer, a known method is appropriately selected.

The photoreceptor according to the present embodiment is explained above. According to the photoreceptor of the present embodiment, the generation of fog in the formed image can be suppressed.

< second embodiment: image Forming apparatus

The second embodiment relates to an image forming apparatus. Hereinafter, an image forming apparatus 60 according to the present embodiment will be described with reference to fig. 3 and 4.

The image forming apparatus 60 includes a photoreceptor 101 as an image carrier. The photoreceptor 101 can suppress the generation of fog in the formed image as described in the first embodiment. The image forming apparatus 60 is provided with such a photoreceptor 101, and thus generation of fog in a formed image can be suppressed.

Hereinafter, a case where the image forming apparatus 60 employs the direct transfer method will be described as an example with reference to fig. 3. Fig. 3 is a schematic diagram of an example of the structure of image forming apparatus 60.

The image forming apparatus 60 includes: the photoreceptor 101, the charging section 27, the exposure section 28, the developing section 29, and the transfer section 26 described in the first embodiment. The charging section 27 charges the surface of the photoreceptor 101. The exposure section 28 exposes the surface of the charged photoreceptor 101 to form an electrostatic latent image on the surface of the photoreceptor 101. The developing section 29 develops the electrostatic latent image into a toner image. The transfer section 26 transfers the toner image from the photoreceptor 101 to the transfer object 38. In the case where the image forming apparatus 60 employs the direct transfer method, the transfer section 26 is a transfer roller 41. The transferred body 38 is a recording medium (such as 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 a monochrome image forming apparatus or a color image forming apparatus, for example. The image forming apparatus 60 may be a tandem type color image forming apparatus for forming toner images of respective colors using toners of different colors.

The image forming apparatus 60 will be described below by taking a tandem color image forming apparatus as an example. The image forming apparatus 60 includes a plurality of photosensitive members 101 and a plurality of developing units 29 arranged side by side in a predetermined direction. The plurality of developing units 29 are each disposed to face the photosensitive member 101. The developing unit 29 carries and conveys toner, and supplies the toner to the surface of the corresponding photoreceptor 101.

As shown in fig. 3, the image forming apparatus 60 further has a box-shaped apparatus housing 70. The paper feeding unit 80, the image forming unit 90, and the fixing unit 10 are provided in the apparatus housing 70. The paper feed portion 80 feeds the paper P. The image forming unit 90 transfers a toner image based on image data to the sheet P while conveying the sheet P fed from the sheet feeding unit 80. After the unfixed toner image is transferred to the paper P in the image forming section 90, the fixing section 10 fixes the unfixed toner image to the paper P. Further, a paper discharge portion 11 is provided on the top surface of the machine case 70. The sheet P subjected to the fixing process in the fixing section 10 is discharged by the sheet discharge section 11.

The paper feeding unit 80 includes a paper feeding cassette 12, a first pickup roller 13, a plurality of paper feeding rollers 14, and a registration roller pair 17. The paper supply cassette 12 is provided to be detachable with respect to the machine housing 70. In the paper feed cassette 12, paper sheets P of various sizes are stored. The first pickup roller 13 is disposed at an upper left position of the sheet feeding 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 convey the paper P taken out by the first pickup roller 13. The registration roller pair 17 temporarily waits the sheet P conveyed by the plurality of paper feed rollers 14, and then feeds the sheet P to the image forming unit 90 for a predetermined time.

The paper feeding unit 80 may further include a manual paper feed tray (not shown) and a second pickup roller 18 (see fig. 4). The manual feed tray is mounted on the left side surface of the machine housing 70. The second pickup roller takes out the paper P placed on the manual feed tray. The sheet P taken out by the second pickup roller is conveyed by the sheet feeding roller 14, and is fed to the image forming portion 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. In the image forming unit 19, 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 are provided in this order from the upstream side (left side in fig. 3) toward the downstream side in the rotation direction of the transfer belt 40 with respect to the black toner supply unit 22. At the center of each of the

units

22, 23, 24, and 25, a photosensitive body 101 is provided. The photosensitive body 101 is provided to be rotatable in an arrow (counterclockwise) direction. Around each of the photosensitive bodies 101, with the charging section 27 as a reference, there are arranged in order from the upstream side in the rotation direction of each photosensitive body 101: a charging section 27, an exposure section 28, a developing section 29, and a transfer section 26.

One or both of a cleaning device (not shown) and a static eliminator (not shown) may be provided upstream of the charging unit 27 in the rotation direction of the photoreceptor 101. After the transfer of the toner image onto the sheet P is completed, the cleaning device and the static eliminator perform cleaning and static elimination, respectively, on the circumferential surface of the photoreceptor 101. The peripheral surface of the photoreceptor 101 cleaned and electrostatically eliminated by the cleaning device and the static eliminator is sent to the charging unit 27, and the charging process is performed again. When the image forming apparatus 60 includes the cleaning device and the charge remover, the charging unit 27, the exposure unit 28, the developing unit 29, the transfer unit 26, the cleaning device, and the charge remover are arranged in this order with respect to the charging unit 27 from the upstream side in the rotation direction of each photosensitive body 101.

As described above, the charging section 27 charges the surface (circumferential surface) of the photoreceptor 101. The charging polarity of the charging section 27 is not particularly limited. When the photoreceptor 101 is a single-layer photoreceptor including a single-layer photosensitive layer 103c (see fig. 1A and 1B), the charging section 27 preferably charges the surface of the photoreceptor 101 with a positive polarity in order to improve sensitivity characteristics. When the photoreceptor 101 is a laminated photoreceptor, the charging section 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 of a non-contact type or a contact type. The non-contact type charging unit 27 applies a voltage without contacting the photoreceptor 101. The non-contact type charging unit 27 is, for example, a corona discharge type charging device, and more specifically, a corotron charger or a grid corotron charger, for example. The contact type charging unit 27 contacts the photoreceptor 101 to apply a voltage. The contact-type charging portion 27 is, for example, a contact (proximity) discharge-type charging device, more specifically, a charging roller or a charging brush, for example. The charging section 27 is preferably a charging roller.

Examples of the charging roller include: and a charging roller which rotates in response to the rotation of the photoreceptor 101 in a state of being in contact with the photoreceptor 101. The charging roller is formed of, for example, resin at least at a surface portion. Specifically, the charging roller includes: the mandrel bar includes a mandrel bar supported to be rotatable about an axis, a resin layer formed on the mandrel bar, and a voltage applying section for applying a voltage to the mandrel bar. The charging unit 27 including such a charging roller applies a voltage to the mandrel bar by the voltage applying unit to charge the surface of the photoreceptor 101 in contact with the resin layer therebetween.

The resin of the resin layer forming the charging roller is not particularly limited as long as it can favorably charge the surface of the photoreceptor 101. Specific examples of the resin forming the resin layer include: silicone resin, polyurethane resin, or silicone modified resin. The resin layer may contain an inorganic filler.

In the case where the image forming apparatus 60 includes the contact-type charging section 27, it is considered that the emission of the active gas (for example, ozone or nitrogen oxide) generated by the charging section 27 can be suppressed. It can be considered that: as a result, deterioration of the photosensitive layer 103 due to the active gas is suppressed, and a user-friendly design of the office environment can be realized.

The voltage applied by the charging section 27 is not particularly limited. Examples of the voltage applied by the charging section 27 include: an alternating voltage, a direct voltage, or a superimposed voltage in which an alternating voltage is superimposed on a direct voltage. Of these, it is preferable that only the dc voltage is applied to the charging unit 27. The charging unit 27 to which only the dc voltage is applied has the following advantages as compared with the charging unit 27 to which the ac voltage is applied or the charging unit 27 to which the superimposed voltage of the ac voltage is applied is superimposed. When the charging section 27 applies only the dc voltage, the voltage applied to the photoreceptor 101 is constant, and thus the surface of the photoreceptor 101 is easily uniformly charged to a constant potential. When only a dc voltage is applied to the charging section 27, the amount of abrasion of the photosensitive layer 103 tends to decrease. As a result, it is considered that a favorable image can be formed.

The voltage applied to the photoreceptor 101 by the charging section 27 is preferably 1000V to 2000V, more preferably 1200V to 1800V, and particularly preferably 1400V to 1600V.

The exposure section 28 is, for example, an exposure device, more specifically, a laser scanning unit, for example. The exposure section 28 exposes the surface of the charged photoreceptor 101 to form an electrostatic latent image on the surface of the photoreceptor 101. Specifically, the charging section 27 charges the circumferential surface of the photoreceptor 101, a host device such as a personal computer inputs image data, and the exposure section 28 irradiates the circumferential surface of the photoreceptor 101 with laser light based on the image data. Thereby, an electrostatic latent image based on image data is formed on the circumferential surface of the photoreceptor 101.

The developing section 29 develops the electrostatic latent image into 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 image data. The developing unit 29 is, for example, a developing device.

The developing unit 29 can develop the electrostatic latent image into a toner image while contacting the photoreceptor 101. That is, the image forming apparatus 60 according to the present embodiment may employ a so-called contact development system.

The developing unit 29 can clean the surface of the photoreceptor 101. That is, the image forming apparatus 60 according to the present embodiment may adopt a cleanerless system. The developing unit 29 can remove components (hereinafter, sometimes referred to as "residual components") remaining on the surface of the photoreceptor 101. Examples of the residual components include: toner components (more specifically, toner or free external additives, etc.) or non-toner components (more specifically, paper powder, etc.).

In the image forming apparatus 60 employing one or both of the contact development method and the cleanerless method, the toner is usually triboelectrically charged by a difference in rotational speed between the developing section 29 (e.g., developing roller) and the photosensitive member 101 at the time of development. Therefore, triboelectrification of the toner is insufficient, and fog is likely to be generated in the formed image. However, the image forming apparatus 60 of the present embodiment includes the photoreceptor 101 capable of suppressing fog as described above. Therefore, image forming apparatus 60 according to the present embodiment can suppress the generation of fog in the formed image even if one or both of the contact development system and the cleanerless system is adopted.

In order to effectively clean the surface of the photoreceptor 101 by the developing unit 29, the following conditions (1) and (2) are preferably satisfied.

Condition (1): in the contact development method, a difference in rotation speed 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 photoreceptor 101 and the absolute value of the potential of the developing bias satisfies the following expressions (2-1) and (2-2).

0(V) < Absolute value of potential of developing bias (V) < Absolute value of surface potential of unexposed region of photosensitive body 101 (V) … … (2-1)

Absolute value of potential of developing bias (V) > absolute value of surface potential of exposure region of photoreceptor 101 (V) > 0(V) … … (2-2)

As shown in condition (1), when the contact development method is employed and a difference in rotation speed is provided between the photosensitive body 101 and the developing portion 29, the surface of the photosensitive body 101 contacts the developing portion 29, and the residual component on the surface of the photosensitive body 101 is removed by friction with the developing portion 29.

Rotation speed V of the photoreceptor 101_PThe (peripheral speed) is preferably 120 mm/sec to 350 mm/sec. Rotational speed V of developing unit 29_DThe (peripheral speed) is preferably 133 mm/sec to 700 mm/sec. The rotation speed V of the photoreceptor 101_PAnd the rotational speed V of the developing part 29_DThe ratio of (A) to (B) preferably satisfies the formula (1-1). In addition, at this ratio V_P/V_DThe case other than 1 indicates that a difference in rotation speed is provided between the photosensitive member 101 and the developing unit 29.

0.5≤V_P/V_D≤0.8……(1-1)

The formula (2-1) of the condition (2) relates to the surface potential of the unexposed area of the photoreceptor 101, which is not exposed by the exposed portion 28. The formula (2-2) of the condition (2) relates to the surface potential of the exposed region of the photoreceptor 101 exposed to the light by the exposed portion 28. After the transfer section 26 transfers the toner image from the photoreceptor 101 to the transferred body 38, the surface potential of the unexposed area and the surface potential of the exposed area of the photoreceptor 101 are measured before the charging section 27 charges the surface of the photoreceptor 101 of the next turn. In the case where the photoreceptor 101 is a single-layer type photoreceptor, the potential of the developing bias, the surface potential of the unexposed area of the photoreceptor 101, and the surface potential of the exposed area of the photoreceptor 101 may be positive values, for example. In the case where the photoreceptor 101 is a laminated photoreceptor, the potential of the developing bias, the surface potential of the unexposed area of the photoreceptor 101, and the surface potential of the exposed area of the photoreceptor 101 may be, for example, negative values.

In the condition (2), when the photoreceptor 101 is a single-layer type photoreceptor, for example, the charge polarity of the toner is a positively charged property, and the development method is a reversal development method. When the photoreceptor 101 is a laminated photoreceptor, for example, the charge polarity of the toner is negatively charged, and the development system is a reversal development system. As shown in condition (2), when a difference is provided between the absolute value of the potential of the developing bias and the absolute value of the surface potential of the photosensitive body 101, the absolute value of the surface potential (charged potential) of the photosensitive body 101 and the absolute value of the potential of the developing bias satisfy the formula (2-1) in the unexposed area, and therefore the electrostatic repulsive force acting between the residual toner (hereinafter, sometimes referred to as residual toner) and the unexposed area of the photosensitive body 101 is larger than the electrostatic repulsive force acting between the residual toner and the developing portion 29. Thereby, the residual toner in the unexposed area of the photoreceptor 101 moves from the surface of the photoreceptor 101 to the developing unit 29 and is collected.

As shown in condition (2), when a difference is provided between the absolute value of the potential of the developing bias and the absolute value of the surface potential of the photosensitive body 101, the absolute value of the surface potential (sensitivity potential) of the photosensitive body 101 and the absolute value of the potential of the developing bias satisfy the formula (2-2) in the exposure region, and therefore, the electrostatic repulsive force acting between the residual toner and the exposure region of the photosensitive body 101 is smaller than the electrostatic repulsive force acting between the toner and the developing portion 29. Therefore, the residual toner of the exposed area of the photosensitive body 101 remains on the surface of the photosensitive body 101. The toner remaining in the exposed area of the photoreceptor 101 is directly used in 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 photoreceptor 101 is, for example, 450V or more and 900V or less. The absolute value of the sensitivity potential of the photoreceptor 101 is, for example, 50V to 200V. The difference between the absolute value of the potential of the developing bias and the absolute value of the charged potential of the photoreceptor 101 is, for example, 100V to 700V. The difference between the absolute value of the potential of the developing bias and the absolute value of the sensitivity potential of the photoreceptor 101 is, for example, 150V to 300V. Here, the potential difference represents an absolute value of the difference. In the case where the photoreceptor 101 is a single-layer type photoreceptor, the conditions for setting such a potential difference are, for example: the potential of the developing bias is set to +330V, the charging potential of the photosensitive body 101 is set to +600V, and the sensitivity potential of the photosensitive body 101 is set to + 100V.

The transfer section 26 (i.e., transfer roller 41) transfers the toner image formed on the surface of the photosensitive body 101 onto a transfer target 38 (recording medium, specifically, paper P). Specifically, the transfer belt 40 is an endless belt-shaped rotating body. The transfer belt 40 is stretched over a driving roller 30, a driven roller 31, a support roller 32, and a plurality of transfer rollers 41. The transfer belt 40 is disposed such that the peripheral surface of each photoreceptor 101 abuts against the surface (contact surface) of the transfer belt 40. Each transfer roller 41 is disposed so as to face each photosensitive body 101, and the transfer belt 40 is pressed against the photosensitive body 101 by each transfer roller 41. In the pressed state, the transfer belt 40 is endlessly rotated by the

several rollers

30, 31, 32, and 41. The driving roller 30 is driven to rotate by a driving source such as a stepping motor, and provides a driving force for endlessly rotating the transfer belt 40. The driven roller 31, the support roller 32, and the transfer roller 41 are provided to rotate freely. As the driving roller 30 causes the endless rotation of the transfer belt 40, the driven roller 31, the support roller 32, and the several transfer rollers 41 are rotated in a driven manner. These

rollers

31, 32, and 41 support the transfer belt 40 while being rotated in a driven manner. The paper P fed from the registration roller pair 17 is adsorbed onto the transfer belt 40 by the adsorption roller 42. The paper P attracted to the transfer belt 40 passes between each photosensitive body 101 and the corresponding transfer roller 41 as the transfer belt 40 rotates.

When the transfer roller 41 transfers the toner image from the photosensitive body 101 to the paper P, the photosensitive body 101 comes into contact with the paper P. Specifically, each transfer roller 41 applies a transfer bias (specifically, a bias having a polarity opposite to the charging polarity of the toner) to the paper P adsorbed on the transfer belt 40. Thereby, the toner image formed on the photosensitive member 101 is transferred to the paper P between each photosensitive member 101 and the corresponding transfer roller 41. The transfer belt 40 rotates in a loop in the arrow (clockwise) direction by the driving of the driving roller 30. At the same time, the paper P adsorbed on the transfer belt 40 passes between each photosensitive body 101 and the corresponding transfer roller 41 in sequence. When the toner image passes, the toner images of the respective colors formed on the respective photosensitive members 101 are sequentially transferred onto the sheet P in a state of being overlaid.

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

The sheet P with the fixed toner image is conveyed by a plurality of conveying rollers 36 and discharged from the sheet discharge portion 11. The sheet discharge portion 11 is formed by recessing the top of the machine case 70. At the bottom of the recessed portion, a discharge tray 37 that receives the discharged sheet P is provided. The image forming apparatus 60 adopting the direct transfer method according to one embodiment of the present embodiment is described above with reference to fig. 3.

In addition, the image forming apparatus 60 of the present embodiment may employ an intermediate transfer system. Next, an image forming apparatus 60 according to another embodiment of the present embodiment will be described with reference to fig. 4. The image forming apparatus 60 in fig. 4 employs an intermediate transfer system. In the image forming apparatus 60 of fig. 4, the transfer section 26 is the primary transfer roller 33 and the secondary transfer roller 21. The transferred body 38 is the intermediate transfer belt 20 and a recording medium (such as paper) P. In fig. 4, the same reference numerals are used for elements corresponding to those in fig. 3, and redundant description is omitted.

The intermediate transfer belt 20 is an endless belt-shaped rotating body. The intermediate transfer belt 20 is stretched over a driving roller 30, a driven roller 31, a support roller 32, and a plurality of primary transfer rollers 33. The intermediate transfer belt 20 is disposed such that the peripheral surfaces of the plurality of photosensitive bodies 101 are in contact with the surface (contact surface) of the intermediate transfer belt 20.

The primary transfer rollers 33 are disposed so as to face the respective photosensitive bodies 101, and the intermediate transfer belt 20 is pressed against the photosensitive bodies 101 by the primary transfer rollers 33. In the pressed state, the intermediate transfer belt 20 is endlessly rotated in an arrow (counterclockwise rotation) direction by the drive roller 30. The driving roller 30 is driven to rotate by a driving source such as a stepping motor, and provides a driving force for endlessly rotating the intermediate transfer belt 20. The driven roller 31, the support roller 32, and the several primary transfer rollers 33 are provided to rotate freely. The driven roller 31, the support roller 32, and the primary transfer roller 33 are rotated in a driven manner as the driving roller 30 causes the endless rotation of the intermediate transfer belt 20. The driven roller 31, the support roller 32, and the primary transfer roller 33 are driven by the intermediate transfer belt 20 to rotate in accordance with the driving rotation of the drive 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 images formed on the photosensitive bodies 101 are sequentially transferred (primary transfer) onto the intermediate transfer belt 20 that rotates around between the photosensitive bodies 101 and the primary transfer roller 33.

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 sheet P. As a result, the toner image primarily transferred to the intermediate transfer belt 20 is transferred to the sheet P between the secondary transfer roller 21 and the support roller 32. Thereby, the unfixed toner image is transferred onto the sheet P.

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

The image forming apparatus 60 adopting the intermediate transfer method according to the other embodiment of the present embodiment is described above with reference to fig. 4.

As described above with reference to fig. 3 and 4, the image forming apparatus 60 according to the present embodiment includes the photosensitive member 101 according to the first embodiment. The photoreceptor 101 can suppress the generation of fog in the formed image. Therefore, according to the image forming apparatus 60 of the present embodiment, the generation of fog in the formed image can be suppressed.

< third embodiment: treatment Cartridge >

The third embodiment relates to a process cartridge. The process cartridge is a process cartridge for image formation. Hereinafter, the process cartridge according to the present embodiment will be described with continued reference to fig. 3 and 4. The process cartridge according to the present embodiment is regarded as each of the black toner supply unit 22, the cyan toner supply unit 23, the magenta toner supply unit 24, and the yellow toner supply unit 25. The process cartridge includes, for example, the photosensitive body 101 according to the first embodiment. The photosensitive body 101 may be already unitized. The process cartridge may be detachably mounted to the image forming apparatus 60 according to the second embodiment. The process cartridge includes, for example, in addition to the photosensitive body 101, at least 1 member of the charging section 27, the exposing section 28, the developing section 29, and the transferring section 26 (i.e., the transfer roller 41 or the primary transfer roller 33) described in the second embodiment. The process cartridge may further include one or both of a cleaning device (not shown) and a remover (not shown).

The process cartridge according to the present embodiment is described above with reference to fig. 3 and 4. The process cartridge according to the present embodiment includes the photosensitive body 101 according to the first embodiment. The photoreceptor 101 can suppress the generation of fog in the formed image. Therefore, according to the process cartridge of the present embodiment, the generation of fog in the formed image can be suppressed. Further, since such a process cartridge is easy to handle, when the sensitivity characteristics and the like of the photosensitive body 101 deteriorate, the process cartridge including the photosensitive body 101 can be replaced easily and quickly.

[ examples ] A method for producing a compound

The present invention will be described in more detail with reference to examples. However, the present invention is not limited in any way to the scope of the examples.

<1. Material for Single layer type photoreceptor >

As materials for forming the single-layer photosensitive layer of the single-layer photoreceptor, the following charge generating agent, hole transporting agent, binder resin, electron transporting agent, and additive were prepared.

(Charge generating agent)

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

(hole transport agent)

The compound (H-3) described in the first embodiment is prepared as a hole transporting agent.

(Binder resin)

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

(Electron transport agent)

The compound (E-1) described in the first embodiment is prepared as an electron transporting agent.

(additives)

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

[ CHEM 22 ]

[ CHEM 23 ]

[ CHEM 24 ]

[ CHEM 25 ]

[ CHEM 26 ]

[ CHEM 27 ]

<2 > production of Single-layer photoreceptor

Single-layer photoreceptors (P-1) to (P-41) were produced using the prepared material for forming the photosensitive layer.

<2-1 > production of Single-layer photoreceptor (P-2)

In a container, 2 parts by mass of a compound (C-lX) as a charge generating agent, 50 parts by mass of a compound (H-3) as a hole transporting agent, 30 parts by mass of a compound (E-1) as an electron transporting agent, 100 parts by mass of a resin (R-la) as a binder resin, 3 parts by mass of a compound (A-1) as an additive, and 600 parts by mass of tetrahydrofuran as a solvent were placed. 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 vessel were mixed using a ball mill for 12 hours to disperse the material in the solvent. Thus, a coating liquid for a monolayer photosensitive layer was obtained. The coating liquid for the monolayer photosensitive layer was coated on a conductive substrate (aluminum base pipe) by a dip coating method. The coating liquid for the monolayer photosensitive layer applied was dried with hot air at 120 ℃ for 80 minutes. Thus, a monolayer type photosensitive layer (film thickness: 30 μm) was formed on the conductive substrate. As a result, a single-layer photoreceptor (P-2) was obtained.

<2-2 > production of Single-layer photoreceptors (P-1) and (P-3) to (P-41)

The single-layer type photoreceptors (P-1) and (P-3) to (P-41) were manufactured by the same method as the single-layer type photoreceptor (P-2) except for changing the following points. The compound (A-1) used for the production of the single-layer photoreceptor (P-2) was changed to the additive of the type shown in Table 1. The content (addition amount) of the additive in the production of the single-layer photoreceptor (P-2) was 3 parts by mass with respect to 100 parts by mass of the binder resin, and the content was changed to the content shown in table 1.

<3. evaluation of Electrical characteristics >

The electrical characteristics of the obtained single-layer photoreceptors (P-1) to (P-41) were evaluated. The electrical characteristics were evaluated under an environment of a temperature of 23 ℃ and a humidity of 50% RH (units of relative humidity). First, the surface of the single layer type photoreceptor was charged to +600V using a drum sensitivity tester (manufactured by GENTEC corporation). Then, monochromatic light (wavelength of 780nm, half-width of 20nm, light energy of 1.5. mu.J/cm) was extracted from the white light of the halogen lamp using a band-pass filter²). The extracted monochromatic light is irradiated onto the surface of the single-layer type photoreceptor. The surface potential of the single layer type photoreceptor was measured at 0.5 second after the irradiation was completed. Measured surface potential as the sensitometric potential (V)_LUnit + V). The sensitivity potential (V) of the single layer type photoreceptor was measured according to the following evaluation criteria_L) Evaluation was carried out. The smaller the absolute value of the sensitivity potential is, the better the electrical characteristics of the single layer type photoreceptor are. Sensitive potential (V) of single layer type photoreceptor_L) And the evaluation results are shown in tables 1 and 2.

Evaluation criterion of electrical characteristics

Evaluation A: the sensitivity potential is less than + 130V.

Evaluation B: the sensitivity potential is +130V or more and less than + 150V.

Evaluation C: the sensitivity potential is +150V or more.

<4. evaluation of fog resistance >

For each of the obtained single-layer type photoreceptors (P-1) to (P-41), fog resistance on the formed image was evaluated. An image forming apparatus (a changer of "monochrome printer FS-1300D" manufactured by Kyowa office information systems Co., Ltd.) was used as an evaluation device. The image forming apparatus employs a contact development system and a cleanerless system. In this image forming apparatus, the developing section cleans toner remaining on the photoreceptor. The paper was "Beijing porcelain office information system brand paper VM-A4" (size A4) sold by Beijing porcelain office information system corporation. In the evaluation using the evaluation apparatus, a one-component developer (trial production sample) was used.

Using an evaluation apparatus, image I was continuously printed on 12000 sheets of paper under the condition that the rotation speed of the single-layer type photoreceptor was 168 mm/sec. Image I is an image with 1% print coverage. Next, a blank image was printed on 1 sheet of paper. The printing was carried out at a temperature of 32.5 ℃ and a humidity of 80% RH. For the obtained blank image, the image density at 3 in the blank image was measured using a reflection densitometer ("RD 914" manufactured by X-rite corporation). The sum of the image densities at 3 of the blank image is divided by the number of measurement positions. Thereby, an arithmetic average of the image density of the blank image is obtained. The image density of the reference sheet was subtracted from the arithmetic average of the image densities of the blank images, and the resultant value was taken as the fog density. The measured fog density was evaluated according to the following evaluation criteria. The single layer type photoreceptor evaluated as a or B was evaluated to have good fog resistance. The Fog Density (FD) and the evaluation results are shown in tables 1 and 2.

Evaluation criteria for fog resistance

Evaluation A: the density of the fog is less than 0.010.

Evaluation B: the density of the fog is more than 0.010 and less than 0.020.

Evaluation C: the density of the fog is more than 0.020.

<5. comprehensive evaluation >

The photoreceptor was evaluated comprehensively based on the results of the evaluation of the fog resistance and the evaluation of the electrical characteristics of the photoreceptor according to the evaluation criteria described below. The results of the comprehensive evaluation are shown in tables 1 and 2. The evaluation was that the photoreceptors A to D were acceptable.

Evaluation criteria for comprehensive evaluation

Evaluation A: the evaluation of the fog resistance was A, and the evaluation of the electrical characteristics was A.

Evaluation B: the haze resistance was evaluated as A, and the electrical characteristics were evaluated as B.

Evaluation C: the haze resistance was evaluated as A, and the electrical characteristics were evaluated as C.

Evaluation D: the evaluation of the fog resistance was B, and the evaluation of the electrical characteristics was either A, B or C.

Evaluation E: the evaluation of the fog resistance was C, and the evaluation of the electrical characteristics was either A, B or C.

In tables 1 and 2, V_LAnd FD denotes sensitivity potential and fog density, respectively. In tables 1 and 2, the contents of the additives are: the content (addition amount) of the additive with respect to 100 parts by mass of the resin (R-1a) as the binder resin.

[ TABLE 1 ]

[ TABLE 2 ]

The single-layer photosensitive layer of the single-layer photoreceptors (P-2) to (P-29) contains at least a binder resin and an additive. Contains the compound (1) and the compound (1) as an additive. Specifically, one of the compounds (A-1), (A-2), (A-4) and (A-5) is contained as an additive. Therefore, as shown in Table 1, the evaluation of the antifogging properties of the single layer photoreceptors (P-2) to (P-29) was A or B, and the antifogging properties were excellent.

In the single-layer photoreceptors (P-4) to (P-7), (P-11) to (P-14), (P-18) to (P-21), and (P-25) to (P-28), 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. Therefore, as shown in table 1, in these single layer type photoreceptors, the evaluation of the fog resistance was a, and the evaluation of the electrical characteristics was a or B. Therefore, these photoreceptors are particularly excellent in fog resistance and also excellent in electrical characteristics.

In the single-layer photoreceptors (P-4) to (P-6), (P-11) to (P-13), (P-18) to (P-20), and (P-25) to (P-27), 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. Therefore, as shown in table 1, the evaluation of the fog resistance was a and the evaluation of the electrical characteristics was a in these single layer type photoreceptors. Therefore, these photoreceptors are particularly excellent in fog resistance and electrical characteristics.

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

The single-layer photosensitive layer of the single-layer photoreceptors (P-30) to (P-36) contains a compound (A-3) as an additive. The single layer type photosensitive layers of the single layer type photoreceptors (P-37), (P-38), (P-39), (P-40) and (P-41) contain the compounds (A-6), (A-7), (A-8), (A-9) and (A-10) as additives, respectively. However, the compounds (A-3), (A-6), (A-7), (A-8), (A-9) and (A-10) are not compounds represented by the general formula (1). Therefore, as shown in Table 2, the single-layer photoreceptors (P-30) to (P-41) had poor fog resistance.

As can be seen from the above, the photoreceptor of the present invention exhibits the ability to suppress the generation of fog in the formed image. Also, the process cartridge and the image forming apparatus of the present invention exhibit the ability to suppress the generation of fog in the formed image.

[ industrial availability ]

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

Claims

1. An electrophotographic photoreceptor comprising a conductive substrate and a photosensitive layer,

a single-layer type photosensitive layer as the photosensitive layer, the single-layer type photosensitive layer containing a charge generating agent, a binder resin, a hole transporting agent, an electron transporting agent and an additive,

the electron transport agent is a compound represented by the following chemical formula (E-1),

the additive is a compound represented by the following chemical formula (A-1), (A-2) or (A-4),

the additive is contained in an amount of 20 to 30 parts by mass based on 100 parts by mass of the binder resin,

2. the electrophotographic photoreceptor according to claim 1,

the monolayer type photosensitive layer is configured as an outermost surface layer.

3. A kind of processing box is disclosed, which comprises a box body,

the electrophotographic photoreceptor according to claim 1.

4. An image forming apparatus includes:

an electrophotographic photoreceptor according to claim 1;

a charging section that charges a surface of the electrophotographic photoreceptor;

an exposure section that exposes the surface of the electrophotographic photoreceptor charged to form an electrostatic latent image on the surface of the electrophotographic photoreceptor;

a developing section that develops the electrostatic latent image into a toner image; and

and a transfer section for transferring the toner image from the electrophotographic photoreceptor to a transfer object.

5. The image forming apparatus according to claim 4,

the developing section develops the electrostatic latent image into the toner image while contacting the electrophotographic photoreceptor.

6. The image forming apparatus according to claim 4,

the developing section cleans the surface of the electrophotographic photoreceptor.

7. The image forming apparatus according to claim 4,

the transferred body is a recording medium,

when the transfer portion transfers the toner image from the electrophotographic photoreceptor to the recording medium, the electrophotographic photoreceptor is brought into contact with the recording medium.

8. The image forming apparatus according to claim 4,

the charging section is a charging roller.

9. The image forming apparatus according to claim 4,

the charging section charges the surface of the electrophotographic photoreceptor to a positive polarity.