WO2016159244A1

WO2016159244A1 - Positively chargeable single-layer electrophotographic photosensitive body, process cartridge and image forming device

Info

Publication number: WO2016159244A1
Application number: PCT/JP2016/060680
Authority: WO
Inventors: 智文清水; 窪嶋　大輔; 真宍戸; 和隆杉本; 和昭江連
Original assignee: 京セラドキュメントソリューションズ株式会社
Priority date: 2015-04-03
Filing date: 2016-03-31
Publication date: 2016-10-06
Also published as: CN107430359A; CN107430359B

Abstract

This positively chargeable single-layer electrophotographic photosensitive body (1) is provided with a photosensitive layer (3). The photosensitive layer (3) contains a polycarbonate resin, a compound represented by general formula (I), and one or more compounds selected from among compounds represented by general formula (II), (III) or (IV). The Vickers hardness of the polycarbonate resin and the compound represented by general formula (I) is 16.0 HV or more. The Vickers hardness is obtained by subjecting a dispersion, which is obtained by dispersing 30 parts by mass of the compound represented by formula (I) in 100 parts by mass of the polycarbonate resin, to measurement. In general formulae (I), (II), (III) and (IV), the symbols are as defined in the description.

Description

Positively charged single layer type electrophotographic photosensitive member, process cartridge, and image forming apparatus

The present invention relates to a positively charged single layer type electrophotographic photosensitive member, a process cartridge, and an image forming apparatus.

The electrophotographic photoreceptor is used in an electrophotographic image forming apparatus. In general, an electrophotographic photoreceptor includes a photosensitive layer. The photosensitive layer can contain a charge generating agent, a charge transport agent (for example, a hole transport agent and an electron transport agent), and a resin (binder resin) for binding them. An electrophotographic photoreceptor having such a photosensitive layer is called an electrophotographic organic photoreceptor. The photosensitive layer contains a charge transport agent and a charge generator, and can have both functions of charge generation and charge transport in the same layer. Such an electrophotographic organic photoreceptor is referred to as a single layer type electrophotographic photoreceptor.

For example, a naphthalenetetracarboxylic acid diimide derivative is known as an electron transporting agent that can be used for an electrophotographic organic photoreceptor (Patent Document 1).

JP 11-343291 A

However, with the technology described in Patent Document 1, it is difficult to suppress the occurrence of toner filming.

The present invention has been made in view of the above problems, and an object thereof is to provide a positively charged single layer type electrophotographic photosensitive member that suppresses the occurrence of toner filming. Another object of the present invention is to provide a process cartridge and an image forming apparatus that suppress the occurrence of toner filming by including such a positively charged single layer type electrophotographic photosensitive member.

The positively charged single layer type electrophotographic photosensitive member of the present invention includes a photosensitive layer. The photosensitive layer comprises a polycarbonate resin, a compound represented by the following general formula (I), and one or more compounds selected from the following general formulas (II), (III), and (IV). contains. The Vickers hardness of the polycarbonate resin and the compound represented by the general formula (I) is 16.0 HV or more. The Vickers hardness can be obtained by measuring a dispersion in which 30 parts by mass of the compound represented by the general formula (I) is dispersed with respect to 100 parts by mass of the polycarbonate resin.

In the general formula (I), R ₁ , R ₂ , R ₃ , R ₄ , R ₅ , and R ₆ each independently represent a hydrogen atom, an alkyl group, or an alkoxy group. One or more of R ₁ , R ₂ , and R ₃ is an alkyl group or an alkoxy group. One or more of R ₄ , R ₅ , and R ₆ is an alkyl group or an alkoxy group.

In the general formula (II), R ₂₁ and R ₂₂ are each independently an alkyl group, an alkoxy group and a halogen atom which may have a substituent selected from the group consisting of an alkoxy group and a halogen atom. Represents an alkoxy group which may have a substituent selected from the group consisting of: or an aryl group which may have a substituent selected from the group consisting of an alkyl group, an alkoxy group and a halogen atom. R ₂₁ and R ₂₂ are different from each other. R ₂₃ , R ₂₄ and R ₂₅ are each independently a group consisting of an alkyl group, an alkoxy group and a halogen atom which may have a substituent selected from the group consisting of a hydrogen atom, an alkoxy group and a halogen atom. Or an aryl group which may have a substituent selected from the group consisting of an alkyl group, an alkoxy group and a halogen atom. R ₂₆ and R ₂₇ each independently represents a hydrogen atom, an alkyl group, an alkoxy group, or a halogen atom.

In the general formula (III), R ₃₁ and R ₃₂ are each independently an alkyl group, an alkoxy group and a halogen atom which may have a substituent selected from the group consisting of an alkoxy group and a halogen atom. Represents an alkoxy group which may have a substituent selected from the group consisting of: or an aryl group which may have a substituent selected from the group consisting of an alkyl group, an alkoxy group and a halogen atom. R ₃₁ and R ₃₂ are different from each other. R ₃₃ , R ₃₄ and R ₃₅ are each independently a group consisting of an alkyl group, an alkoxy group and a halogen atom which may have a substituent selected from the group consisting of a hydrogen atom, an alkoxy group and a halogen atom. Or an aryl group which may have a substituent selected from the group consisting of an alkyl group, an alkoxy group and a halogen atom. R ₃₆ represents a hydrogen atom, an alkyl group, an alkoxy group, or a halogen atom.

In the general formula (IV), R ₄₁ , R ₄₂ , R ₄₃ , R ₄₄ , and R ₄₅ each independently have a substituent selected from the group consisting of a hydrogen atom, an alkoxy group, and a halogen atom. An alkoxy group which may have a substituent selected from the group consisting of an alkyl group, an alkoxy group and a halogen atom, or a substituent selected from the group consisting of an alkyl group, an alkoxy group and a halogen atom Represents an aryl group which may be substituted. R ₄₆ , R ₄₇ , R ₄₈ , and R ₄₉ represent a hydrogen atom, an alkyl group, an alkoxy group, or a halogen atom.

The process cartridge of the present invention includes the positively charged single layer type electrophotographic photosensitive member described above.

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

According to the positively charged single layer type electrophotographic photosensitive member of the present invention, it is possible to suppress the occurrence of toner filming. Further, according to the process cartridge and the image forming apparatus of the present invention, it is possible to suppress the occurrence of toner filming by including the positively charged single layer type electrophotographic photosensitive member.

It is a schematic sectional drawing which shows an example of the structure of the positively charged single layer type electrophotographic photoreceptor according to the first embodiment of the present invention. It is a schematic sectional drawing which shows an example of the structure of the positively charged single layer type electrophotographic photoreceptor according to the first embodiment of the present invention. It is a schematic sectional drawing which shows an example of the structure of the positively charged single layer type electrophotographic photoreceptor according to the first embodiment of the present invention. It is the schematic which shows the structure of the image forming apparatus which concerns on 2nd embodiment of this invention.

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

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

[First Embodiment: Positively Charged Single-Layer Electrophotographic Photoreceptor]
The first embodiment relates to a positively charged single layer type electrophotographic photosensitive member (hereinafter sometimes referred to as “photosensitive member”). Hereinafter, the photoreceptor 1 of the present embodiment will be described with reference to FIGS. 1A, 1B, and 1C. 1A, 1B, and 1C are schematic cross-sectional views each showing an example of the structure of the photoreceptor 1.

The photoreceptor 1 includes a photosensitive layer 3 as shown in FIG. 1A, for example. The photosensitive layer 3 is provided directly or indirectly on the conductive substrate 2. For example, as shown in FIG. 1A, the photosensitive layer 3 may be provided directly on the conductive substrate 2. Alternatively, for example, as shown in FIG. 1B, an intermediate layer 4 may be appropriately provided between the conductive substrate 2 and the photosensitive layer 3. Further, as shown in FIGS. 1A and 1B, the photosensitive layer 3 may be exposed as the outermost layer. Alternatively, as shown in FIG. 1C, a protective layer 5 may be appropriately provided on the photosensitive layer 3.

The thickness of the photosensitive layer 3 is not particularly limited as long as it can sufficiently function as a photosensitive layer. The thickness of the photosensitive layer 3 is, for example, 5 μm or more and 100 μm or less, and preferably 10 μm or more and 50 μm or less.

Hereinafter, the conductive substrate 2 and the photosensitive layer 3 will be described. Furthermore, the manufacturing method of the intermediate | middle layer 4 and the photoreceptor 1 is demonstrated.

[1. Conductive substrate]
The conductive substrate 2 is not particularly limited as long as it can be used as the conductive substrate of the photoreceptor 1. As the conductive substrate 2, a conductive substrate formed of a material having at least a surface portion having conductivity can be used. Examples of the conductive substrate 2 include a conductive substrate made of a conductive material; or a conductive substrate coated with a conductive material. Examples of the conductive material include aluminum, iron, copper, tin, platinum, silver, vanadium, molybdenum, chromium, cadmium, titanium, nickel, palladium, indium, stainless steel, and brass. These conductive materials may be used alone or in combination of two or more (for example, as an alloy). Among these materials having conductivity, aluminum or an aluminum alloy is preferable because charge transfer from the photosensitive layer 3 to the conductive substrate 2 is good.

The shape of the conductive substrate 2 can be appropriately selected according to the structure of the image forming apparatus 6 to be used (see FIG. 2). For example, a sheet-like conductive substrate 2 or a drum-shaped conductive substrate 2 can be used. Further, the thickness of the conductive substrate 2 can be appropriately selected according to the shape of the conductive substrate 2.

[2. Photosensitive layer]
The photosensitive layer 3 contains a polycarbonate resin, a compound represented by the general formula (I), and one or more of compounds represented by the general formulas (II), (III), and (IV). . Hereinafter, the compounds represented by the general formulas (I), (II), (III), and (IV) are referred to as compounds (I), (II), (III), and (IV), respectively. There is.

First, regarding the compounds (I), (II), (III), and (IV), terms commonly used in the general formulas (I), (II), (III), and (IV) will be described. .

Examples of the “halogen atom” in the general formulas (I), (II), (III), and (IV) include a chloro group and a bromo group.

Examples of the “alkyl group” in the general formulas (I), (II), (III), and (IV) include alkyl groups having 1 to 6 carbon atoms. Examples of the alkyl group having 1 to 6 carbon atoms include methyl group, ethyl group, n-propyl group, iso-propyl group, n-butyl group, iso-butyl group, t-butyl group, n-pentyl group, 1-methylbutyl group, 2-methylbutyl group, 3-methylbutyl group, 1-ethylpropyl group, 1,1-dimethylpropyl group, 1,2-dimethylpropyl group, 2,2-dimethylpropyl group, or 2-ethylhexyl group Is mentioned.

Examples of the “alkoxy group” in the general formulas (I), (II), (III), and (IV) include alkoxy groups having 1 to 6 carbon atoms. Examples of the alkoxy group having 1 to 6 carbon atoms include methoxy group, ethoxy group, n-propoxy group, iso-propoxy group, n-butoxy group, iso-butoxy group, t-butoxy group, n-pentoxy group, 1 -Methoxy group, 2-methylbutoxy group, 3-methylbutoxy group, 1-ethylpropoxy group, 1,1-dimethylpropoxy group, 1,2-dimethylpropoxy group, 2,2-dimethylpropoxy group, or 2-ethylhexyl An oxy group is mentioned.

Examples of the “aryl group” in the general formulas (I), (II), (III), and (IV) include aryl groups having 6 to 14 carbon atoms. Examples of the aryl group having 6 to 14 carbon atoms include a phenyl group and a naphthyl group.

As already described, the photosensitive layer 3 contains a polycarbonate resin, compound (I), and one or more of compounds (II), (III), and (IV). The Vickers hardness of the polycarbonate resin and the compound (I) is 16.0 HV or more. Moreover, it is preferable that the glass transition point of the photosensitive layer 3 is 60.0 degreeC or more. Furthermore, the photosensitive layer 3 can contain a charge generating agent and an electron transporting agent. The photosensitive layer 3 may contain an additive as necessary. Hereinafter, the compounds (I), (II), (III), and (IV), polycarbonate resin, Vickers hardness, charge generator, electron transport agent, glass transition point, and additives will be described.

[2-1. Compound (I)]
The photosensitive layer 3 contains the compound (I). Compound (I) can act as a hole transport agent in the photosensitive layer 3. Further, it is considered that the density of the photosensitive layer 3 can be increased by incorporating the compound (I) in a polycarbonate resin in combination with one or more of the compounds (II), (III), and (IV). It is done. As a result, it is considered that the hardness of the photosensitive layer 3 can be increased.

Compound (I) is represented by general formula (I).

In the general formula (I), R ₁ , R ₂ , R ₃ , R ₄ , R ₅ , and R ₆ each independently represent a hydrogen atom, an alkyl group, or an alkoxy group. One or more of R ₁ , R ₂ , and R ₃ is an alkyl group or an alkoxy group. That is, R ₁ , R ₂ , and R ₃ are not all hydrogen atoms. One or more of R ₄ , R ₅ , and R ₆ is an alkyl group or an alkoxy group. That is, R ₄ , R ₅ , and R ₆ are not all hydrogen atoms.

In the general formula (I), R ₁ , R ₂ , R ₃ , R ₄ , R ₅ , and R ₆ are each independently a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or the number of carbon atoms It preferably represents 1 or more and 6 or less alkoxy groups, and more preferably represents a methyl group or a methoxy group. One or more of R ₁ , R ₂ , and R ₃ are preferably an alkyl group having 1 to 6 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms. More preferably, it is a group. One or more of R ₄ , R ₅ , and R ₆ are preferably an alkyl group having 1 to 6 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms. More preferably, it is a group.

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

The melting point (Mp) of compound (I) is preferably 170 ° C. or lower, more preferably 145 ° C. or higher and 170 ° C. or lower. When the melting point of the compound (I) is within such a range, the Vickers hardness between the polycarbonate resin and the compound (I) tends to increase. The melting point of compound (I) can be measured, for example, by the following method.

(Measuring method of melting point)
The melting point of the compound (I) can be measured using a differential scanning calorimeter (for example, “DSC-6220” manufactured by Seiko Instruments Inc.). After putting 10 mg of the sample (compound (I)) in an aluminum dish, the aluminum dish is set in the measuring part of the DSC. Use an empty aluminum pan for reference. The sample is heated up to 170 ° C. at a rate of 10 ° C./min with 30 ° C. as the measurement start temperature. The maximum peak temperature of the heat of fusion observed when the temperature is raised is taken as the melting point of the sample.

The content of the compound (I) is preferably 10 parts by mass or more and 150 parts by mass or less, and more preferably 40 parts by mass or more and 120 parts by mass or less with respect to 100 parts by mass of the polycarbonate resin. When the content of the compound (I) is within such a range, the occurrence of toner filming tends to be further suppressed. Further, the photosensitive layer 3 having a desired glass transition point tends to be easily obtained.

The photosensitive layer 3 may contain a hole transport agent in addition to the compound (I) as necessary. As the hole transporting agent that can be contained in addition to the compound (I), a known hole transporting agent can be appropriately selected.

[2-2. Compounds (II), (III), and (IV)]
The photosensitive layer 3 contains one or more of compounds (II), (III), and (IV).

Compounds (II), (III), and (IV) are considered to function as, for example, an electron acceptor compound in the photosensitive layer 3. When the contents of the compounds (II), (III), and (IV) are decreased with respect to the mass of the photosensitive layer 3, the compounds (II), (III), and (IV) tend to work as electron acceptor compounds. Become stronger. When the contents of the compounds (II), (III), and (IV) are increased with respect to the mass of the photosensitive layer 3, the compounds (II), (III), and (IV) work as electron transport agents. The tendency becomes stronger.

Furthermore, the compounds (II), (III), and (IV) can be added for the purpose of increasing the glass transition point of the photosensitive layer 3. Compounds (II), (III), and (IV) are considered to act as, for example, a glass transition point adjusting agent in the photosensitive layer 3.

Hereinafter, the compound (II) will be described. Compound (II) is represented by general formula (II).

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

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

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

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

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

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

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

Specific examples of the compound (II) include N, N′-bis (2-methyl-6-ethylphenyl) naphthalene-1,4,5,8-tetracarboxylic acid diimide (represented by the chemical formula (5)). , N, N′-bis (2-ethyl-6-methylphenyl) naphthalene-1,4,5,8-tetracarboxylic acid diimide, N , N′-bis (2,4-dimethyl-6-ethylphenyl) naphthalene-1,4,5,8-tetracarboxylic acid diimide N, N′-bis (2-methyl-6-ethoxyphenyl) naphthalene-1 , 4,5,8-tetracarboxylic acid diimide, N, N′-bis (2-methyl-6-methoxyphenyl) naphthalene-1,4,5,8-tetracarboxylic acid diimide, or N, N′-bis (2-methyl-6- Butoxyethyl phenyl)

naphthalene

1,4,5,8-tetracarboxylic diimide and the like.

Next, compound (III) will be described. Compound (III) is represented by general formula (III).

In the general formula (III), R ₃₁ and R ₃₂ may each independently have an alkyl group which may have a substituent, an alkoxy group which may have a substituent, or a substituent. Represents a good aryl group. When R ₃₁ and R ₃₂ are alkyl groups having a substituent, the substituent is selected from the group consisting of an alkoxy group and a halogen atom. When R ₃₁ and R ₃₂ are an alkoxy group having a substituent, the substituent is selected from the group consisting of an alkoxy group and a halogen atom. When R ₃₁ and R ₃₂ are an aryl group having a substituent, the substituent is selected from the group consisting of an alkyl group, an alkoxy group, and a halogen atom.

R ₃₁ and R ₃₂ each independently preferably represents an alkyl group having 1 to 6 carbon atoms, preferably represents an alkyl group having 1 to 4 carbon atoms, and has 1 or more carbon atoms. More preferably, it represents 2 or less alkyl groups.

R ₃₁ and R ₃₂ are different from each other. For example, R ₃₁ may be an alkyl group and R ₃₂ may be an alkoxy group. For example, when both R ₃₁ and R ₃₂ are alkyl groups, R ₃₁ may be a methyl group and R ₃₂ may be an ethyl group.

R ₃₃ , R ₃₄ , and R ₃₅ may each independently have a hydrogen atom, an alkyl group that may have a substituent, an alkoxy group that may have a substituent, or a substituent. Represents an aryl group. When R ₃₃ , R ₃₄ , and R ₃₅ are an alkyl group having a substituent, the substituent is selected from the group consisting of an alkoxy group and a halogen atom. When R ₃₃ , R ₃₄ , and R ₃₅ are an alkoxy group having a substituent, the substituent is selected from the group consisting of an alkoxy group and a halogen atom. When R ₃₃ , R ₃₄ , and R ₃₅ are an aryl group having a substituent, the substituent is selected from the group consisting of an alkyl group, an alkoxy group, and a halogen atom. R ₃₃ , R ₃₄ , and R ₃₅ preferably represent a hydrogen atom.

R ₃₆ represents a hydrogen atom, an alkyl group, an alkoxy group, or a halogen atom. R ₃₆ preferably represents a hydrogen atom.

Specific examples of compound (III) include a compound represented by chemical formula (7). Hereinafter, the compound represented by the chemical formula (7) may be referred to as “compound (7)”.

Next, compound (IV) will be described. Compound (IV) is represented by general formula (IV).

In the general formula (IV), R ₄₁ , R ₄₂ , R ₄₃ , R ₄₄ , and R ₄₅ each independently have a hydrogen atom, an alkyl group that may have a substituent, or a substituent. Represents a good alkoxy group or an aryl group which may have a substituent. When R ₄₁ , R ₄₂ , R ₄₃ , R ₄₄ , and R ₄₅ are an alkyl group having a substituent, the substituent is selected from the group consisting of an alkoxy group and a halogen atom. When R ₄₁ , R ₄₂ , R ₄₃ , R ₄₄ , and R ₄₅ are an alkoxy group having a substituent, the substituent is selected from the group consisting of an alkoxy group and a halogen atom. When R ₄₁ , R ₄₂ , R ₄₃ , R ₄₄ , and R ₄₅ are aryl groups having a substituent, the substituent is selected from the group consisting of an alkyl group, an alkoxy group, and a halogen atom.

R ₄₁ , R ₄₂ , R ₄₃ , R ₄₄ , and R ₄₅ each independently preferably represent a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, and each represents a hydrogen atom or 1 carbon atom. More preferably, it represents an alkyl group having 4 or less and more preferably a hydrogen atom or an alkyl group having 1 to 2 carbon atoms.

R ₄₆ , R ₄₇ , R ₄₈ , and R ₄₉ represent a hydrogen atom, an alkyl group, an alkoxy group, or a halogen atom. R ₄₆ , R ₄₇ , R ₄₈ , and R ₄₉ preferably represent a hydrogen atom.

Specific examples of the compound (IV) include a compound represented by the chemical formula (6). Hereinafter, the compound represented by the chemical formula (6) may be referred to as “compound (6)”.

The total content of one or more of the compounds (II), (III), and (IV) is preferably 10 parts by mass or more and 60 parts by mass or less with respect to 100 parts by mass of the polycarbonate resin. More preferably, it is at least 40 parts by mass. When the total content of one or more of the compounds (II), (III), and (IV) is within such a range, the photosensitive layer 3 having a desired glass transition point is easily obtained.

The photosensitive layer 3 can also contain two or more (preferably two or three) of compounds (II), (III) and (IV).

[2-3. Polycarbonate resin]
The photosensitive layer 3 contains a polycarbonate resin. The polycarbonate resin can act as a binder resin in the photosensitive layer 3. The polycarbonate resin tends to be excellent in the balance of processability, mechanical properties, optical properties, and / or wear resistance of the photosensitive layer 3.

Examples of the polycarbonate resin include bisphenol Z type polycarbonate resin, bisphenol B type polycarbonate resin, bisphenol CZ type polycarbonate resin, bisphenol C type polycarbonate resin, bisphenol E type polycarbonate resin, bisphenol AP type polycarbonate resin, and bisphenol A type polycarbonate resin. Can be mentioned. Specific examples of the bisphenol Z-type polycarbonate resin include polycarbonate resins having a repeating unit represented by the chemical formula (Bis-Z) described later in Examples. A polycarbonate resin may be used individually by 1 type, and may be used in combination of 2 or more type.

The molecular weight of the polycarbonate resin is preferably 21,000 or more and 52500 or less in terms of viscosity average molecular weight. When the viscosity average molecular weight of the polycarbonate resin is 21,000 or more, the abrasion resistance of the polycarbonate resin can be sufficiently increased, and the photosensitive layer 3 is hardly worn. Moreover, when the molecular weight of the polycarbonate resin is 52500 or less, the polycarbonate resin is easily dissolved in a solvent when the photosensitive layer 3 is formed, and the viscosity of the coating solution for the photosensitive layer does not become too high. As a result, the photosensitive layer 3 can be easily formed.

The photosensitive layer 3 can contain a binder resin in addition to the polycarbonate resin. Examples of the binder resin that can be contained in addition to the polycarbonate resin include a thermoplastic resin, a thermosetting resin, and a photocurable resin. Examples of the thermoplastic resin include styrene resin, styrene-butadiene copolymer, styrene-acrylonitrile copolymer, styrene-maleic acid copolymer, styrene-acrylic acid copolymer, acrylic copolymer, polyethylene resin, Ethylene-vinyl acetate copolymer, chlorinated polyethylene resin, polyvinyl chloride resin, polypropylene resin, ionomer, vinyl chloride-vinyl acetate copolymer, alkyd resin, polyamide resin, urethane resin, polyarylate resin, polysulfone resin, diallyl phthalate Examples thereof include resins, ketone resins, polyvinyl butyral resins, polyether resins, and polyester resins. Examples of the thermosetting resin include silicone resins, epoxy resins, phenol resins, urea resins, melamine resins, and other crosslinkable thermosetting resins. Examples of the photocurable resin include an epoxy acrylate resin and a urethane-acrylate copolymer.

[2-4. Vickers hardness]
The Vickers hardness of the polycarbonate resin and the compound (I) is 16.0 HV or more. The Vickers hardness is preferably 16.0 HV or more and 30.0 HV or less, and more preferably 17.0 HV or more and 20.0 HV or less. When the Vickers hardness is 16.0 HV or more, the occurrence of toner filming tends to be suppressed. The reason is presumed as follows.

The hardness of the photosensitive layer 3 is easily affected by the Vickers hardness between the polycarbonate resin and the compound (I). Therefore, when the Vickers hardness of the polycarbonate resin and the compound (I) is equal to or higher than a specific value, there are the following advantages when the photoreceptor 1 is provided in the image forming apparatus 6 to form an image. When the image forming apparatus 6 is an image forming apparatus 6 that does not include, for example, a contact developing method, the developing unit 29 (see FIG. 2) cleans the toner remaining on the surface of the photoreceptor 1. When the image forming apparatus 6 is an image forming apparatus 6 including a cleaning unit that employs, for example, a non-contact developing method, the cleaning unit cleans toner remaining on the surface of the photoreceptor 1. When the Vickers hardness of the polycarbonate resin and the compound (I) is a specific value or more, when the developing unit 29 (or the cleaning unit) cleans the toner remaining on the surface of the photoconductor 1, the photoconductor 1 and the toner It is thought that the contact area decreases. When the contact area between the photosensitive member 1 and the toner decreases, the toner remaining on the surface of the photosensitive member 1 can be easily scraped off by the developing unit 29 (or the cleaning unit). As a result, by setting the Vickers hardness of the polycarbonate resin and the compound (I) to a specific value or more, the cleaning property of the photosensitive member 1 is improved, and the surface of the photosensitive member 1 is filmed with toner. It is thought that generation can be suppressed. Such a photoreceptor 1 is considered to be able to suppress the occurrence of toner filming and further suppress the deterioration of the photosensitive layer 3 even when the temperature in the image forming apparatus 6 rises during image formation. The image forming apparatus 6 will be described later in the second embodiment.

(Measurement method of Vickers hardness)
The Vickers hardness of the polycarbonate resin and compound (I) can be measured, for example, by the following method. Vickers hardness can be obtained by measuring a dispersion in which 30 parts by mass of compound (I) is dispersed with respect to 100 parts by mass of a polycarbonate resin. Specifically, 30 parts by mass of compound (I) and 100 parts by mass of polycarbonate resin are put into a container. After the contents of the container are mixed and dispersed for 1 hour at 30 ° C. using a disperser (for example, “Precision Emulsion Disperser Creamix (registered trademark) CLM-1.5S” manufactured by M Technique Co., Ltd.) And cured by heating at 120 ° C. for 60 minutes to obtain a dispersion. It is preferable to adjust the dispersion conditions and the curing conditions so that the thickness of the obtained dispersion is 27.5 μm (error range: ± 4.5 μm). The Vickers hardness of the obtained dispersion is measured by a method in accordance with Japanese Industrial Standard (JIS Z2244). For measuring the Vickers hardness, a hardness meter (for example, “Micro Vickers hardness meter DMH-1 type” manufactured by Matsuzawa Co., Ltd. (formerly Matsuzawa Seiki Co., Ltd.)) is used. The Vickers hardness is measured at a temperature of 23 ° C., a diamond indenter load (test force) of 10 gf, a time required to reach the test force of 5 seconds, a diamond indenter approach speed of 2 mm / second, and a test force holding time of 1 second. Can be done under conditions.

The Vickers hardness can be measured by separating the photosensitive layer 3 with a centrifuge, taking out the polycarbonate resin and the compound (I), and using the taken out polycarbonate resin and the compound (I) by the above-described method. it can.

[2-5. Charge generator]
The charge generator is not particularly limited as long as it is a charge generator for a photoreceptor. Examples of the charge generator include phthalocyanine pigments, perylene pigments, bisazo pigments, dithioketopyrrolopyrrole pigments, metal-free naphthalocyanine pigments, metal naphthalocyanine pigments, squaraine pigments, trisazo pigments, indigo pigments, azurenium pigments, and cyanine pigments. Powders of inorganic photoconductive materials (eg, selenium, selenium-tellurium, selenium-arsenic, cadmium sulfide, or amorphous silicon), pyrylium salts, ansanthrone pigments, triphenylmethane pigments, selenium pigments, toluidine pigments, Examples thereof include pyrazoline pigments and quinacridone pigments. Examples of the phthalocyanine pigment include metal-free phthalocyanine represented by the chemical formula (H ₂ Pc) or metal phthalocyanine. Examples of the metal phthalocyanine include titanyl phthalocyanine represented by the chemical formula (TiOPc) or phthalocyanine coordinated with a metal other than titanium oxide (for example, V-type hydroxygallium phthalocyanine). Metal-free phthalocyanine or metal phthalocyanine may be used after derivatization.

The metal-free phthalocyanine may be a crystal. Examples of the metal-free phthalocyanine crystal include X-type metal-free phthalocyanine. The titanyl phthalocyanine may be a crystal. Examples of the titanyl phthalocyanine crystal include α-type titanyl phthalocyanine, β-type titanyl phthalocyanine, and Y-type titanyl phthalocyanine. A charge generating agent may be used individually by 1 type, and may be used in combination of 2 or more type.

A charge generating agent having an absorption wavelength in a desired region may be used alone. Alternatively, two or more charge generating agents having absorption wavelengths in different regions may be used in combination. For example, in a digital optical image forming apparatus (for example, a laser beam printer using a light source such as a semiconductor laser or a facsimile), it is preferable to use a photoconductor having sensitivity in a wavelength region of 700 nm or more. Therefore, for example, phthalocyanine pigments (for example, X-type metal-free phthalocyanine or Y-type titanyl phthalocyanine) are preferably used in the digital optical image forming apparatus. The crystal shape (for example, α-type, β-type, or Y-type) of the phthalocyanine pigment is not particularly limited, and phthalocyanine pigments having various crystal shapes can be used. For a photoreceptor applied to an image forming apparatus using a short wavelength laser light source (for example, a laser light source having a wavelength of about 350 nm or more and 550 nm or less), an ansanthrone pigment or a perylene pigment is suitable as a charge generator. Used for.

The content of the charge generating agent is preferably 0.1 parts by weight or more and 50 parts by weight or less, and 0.5 parts by weight or more and 30 parts by weight or less with respect to 100 parts by weight of the polycarbonate resin in the photosensitive layer 3. Is more preferable.

[2-6. Electron transport agent]
The photosensitive layer 3 can contain an electron transport agent. Examples of electron transport agents include quinone 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, dinitroanthracene, dinitroacridine, succinic anhydride, maleic anhydride, or dibromomaleic anhydride. Examples of the quinone compound include naphthoquinone compounds, diphenoquinone compounds, anthraquinone compounds, azoquinone compounds, nitroanthraquinone compounds, and dinitroanthraquinone compounds. These electron transfer agents may be used alone or in combination of two or more.

Specific examples of quinone compounds include compounds represented by general formula (V), (VI), or (VIII).

Specific examples of the hydrazone compound include a compound represented by the general formula (VII).

Hereinafter, the compounds represented by the general formulas (V), (VI), (VII), and (VIII) may be referred to as compounds (V), (VI), (VII), and (VIII), respectively. is there.

In the general formulas (V), (VI), (VII), and (VIII), R ₁₁ , R ₁₂ , R ₁₃ , R ₁₄ , R ₆₁ , R ₆₂ , R ₇₁ , R ₇₂ , R ₈₁ , R ₈₂ , And R ₈₃ each independently has a hydrogen atom, an alkyl group that may have a substituent, an alkenyl group that may have a substituent, an alkoxy group that may have a substituent, or a substituent. An aralkyl group that may be substituted, an aryl group that may have a substituent, or a heterocyclic group that may have a substituent. R ₇₃ may have a halogen atom, a hydrogen atom, an alkyl group that may have a substituent, an alkenyl group that may have a substituent, an alkoxy group that may have a substituent, or a substituent. It represents a good aralkyl group, an aryl group which may have a substituent, or a heterocyclic group which may have a substituent.

In general formulas (V), (VI), (VII), and (VIII), R ₁₁ , R ₁₂ , R ₁₃ , R ₁₄ , R ₆₁ , R ₆₂ , R ₇₁ , R ₇₂ , R ₇₃ , R ₈₁ , In R ₈₂ and R ₈₃ , the alkyl group includes, for example, an alkyl group having 1 to 10 carbon atoms, preferably an alkyl group having 1 to 6 carbon atoms, and having 1 to 5 carbon atoms. An alkyl group is more preferable, and a methyl group, a tert-butyl group, or a 1,1-dimethylpropyl group is particularly preferable. The alkyl group may be a linear alkyl group, a branched alkyl group, a cyclic alkyl group (cycloalkyl group), or an alkyl group combining these. The alkyl group may have a substituent. Examples of the substituent include a halogen atom, a hydroxyl group, an alkoxy group having 1 to 4 carbon atoms, or a cyano group. The number of substituents is not particularly limited, but is preferably 3 or less.

In general formulas (V), (VI), (VII), and (VIII), R ₁₁ , R ₁₂ , R ₁₃ , R ₁₄ , R ₆₁ , R ₆₂ , R ₇₁ , R ₇₂ , R ₇₃ , R ₈₁ , In R ₈₂ and R ₈₃ , examples of the alkenyl group include alkenyl groups having 2 to 10 carbon atoms, preferably alkenyl groups having 2 to 6 carbon atoms, and having 2 to 4 carbon atoms. An alkenyl group is more preferred. The alkenyl group may be a linear alkenyl group, a branched alkenyl group, a cyclic alkenyl group, or an alkenyl group combining these. The alkenyl group may have a substituent. Examples of the substituent include a halogen atom, a hydroxyl group, an alkoxy group having 1 to 4 carbon atoms, or a cyano group. The number of substituents is not particularly limited, but is preferably 3 or less.

In general formulas (V), (VI), (VII), and (VIII), R ₁₁ , R ₁₂ , R ₁₃ , R ₁₄ , R ₆₁ , R ₆₂ , R ₇₁ , R ₇₂ , R ₇₃ , R ₈₁ , In R ₈₂ and R ₈₃ , examples of the alkoxy group include an alkoxy group having 1 to 10 carbon atoms, an alkoxy group having 1 to 6 carbon atoms is preferable, and an alkoxy group having 1 to 4 carbon atoms is preferable. An alkoxy group is more preferable. The alkoxy group may be a linear alkoxy group, a branched alkoxy group, a cyclic alkoxy group, or an alkoxy group that combines these. The alkoxy group may have a substituent. Examples of the substituent include a halogen atom, a hydroxyl group, an alkoxy group having 1 to 4 carbon atoms, a phenyl group, and a cyano group. The number of substituents is not particularly limited, but is preferably 3 or less.

In general formulas (V), (VI), (VII), and (VIII), R ₁₁ , R ₁₂ , R ₁₃ , R ₁₄ , R ₆₁ , R ₆₂ , R ₇₁ , R ₇₂ , R ₇₃ , R ₈₁ , In R ₈₂ and R ₈₃ , examples of the aralkyl group include aralkyl groups having 7 to 15 carbon atoms, aralkyl groups having 7 to 13 carbon atoms are preferable, and those having 7 to 12 carbon atoms are preferable. Aralkyl groups are more preferred. The aralkyl group may have a substituent. Examples of the substituent include a halogen atom, a hydroxyl group, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a nitro group, a cyano group, and a fat having 2 to 4 carbon atoms. An acyl group, a benzoyl group, a phenoxy group, an alkoxycarbonyl group containing an alkoxy group having 1 to 4 carbon atoms, or a phenoxycarbonyl group. The number of substituents is not particularly limited, but is preferably 5 or less, and more preferably 3 or less.

In general formulas (V), (VI), (VII), and (VIII), R ₁₁ , R ₁₂ , R ₁₃ , R ₁₄ , R ₆₁ , R ₆₂ , R ₇₁ , R ₇₂ , R ₇₃ , R ₈₁ , In R ₈₂ and R ₈₃ , the aryl group includes, for example, a phenyl group, a group formed by condensing two or three benzene rings, or two or three benzene rings formed by a single bond. A group formed by linking may be mentioned. The number of benzene rings contained in the aryl group is, for example, 1 or more and 3 or less, and preferably 1 or 2. Examples of the substituent that the aryl group may have include, for example, a halogen atom, a hydroxyl group, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a nitro group, a cyano group, and carbon. Examples thereof include an aliphatic acyl group having 2 to 4 atoms, a benzoyl group, a phenoxy group, an alkoxycarbonyl group containing an alkoxy group having 1 to 4 carbon atoms, or a phenoxycarbonyl group.

In general formulas (V), (VI), (VII), and (VIII), R ₁₁ , R ₁₂ , R ₁₃ , R ₁₄ , R ₆₁ , R ₆₂ , R ₇₁ , R ₇₂ , R ₇₃ , R ₈₁ , In R ₈₂ and R ₈₃ , examples of the heterocyclic group include a 5-membered or 6-membered monocyclic heterocyclic group containing one or more heteroatoms selected from the group consisting of N, S, and O; A heterocyclic group in which such single rings are condensed; or a heterocyclic group in which such a single ring is condensed with a 5-membered or 6-membered hydrocarbon ring. When the heterocyclic group is a condensed ring, the number of rings contained in the condensed ring is preferably 3 or less. Examples of the substituent that the heterocyclic group may have include, for example, a halogen atom, a hydroxyl group, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a nitro group, a cyano group, Examples thereof include an aliphatic acyl group having 2 to 4 carbon atoms, a benzoyl group, a phenoxy group, an alkoxycarbonyl group containing an alkoxy group having 1 to 4 carbon atoms, or a phenoxycarbonyl group.

In R ₇₃ in general formula (VII), examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom, and a chlorine atom is preferable.

Specific examples of compounds (V), (VI), (VII), and (VIII) include compounds represented by chemical formulas (13) to (17). Hereinafter, the compounds represented by the chemical formulas (13) to (17) may be referred to as compounds (13) to (17), respectively.

Among the compounds (V), (VI), (VII), and (VIII), the photosensitive layer 3 preferably contains the compound (V) from the viewpoint of suppressing the occurrence of toner filming.

From the viewpoint of suppressing the occurrence of toner filming, R ₁₁ , R ₁₂ , R ₁₃ , and R ₁₄ in the general formula (V) each independently represent an alkyl group, an aryl group, or an alkoxy group. And more preferably an alkyl group having 1 to 6 carbon atoms, and particularly preferably a methyl group or a tert-butyl group.

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 polycarbonate resin.

[2-7. Glass transition point]
The glass transition point (Tg) of the photosensitive layer 3 is preferably 60.0 ° C. or higher. When the glass transition point is within such a range, the photosensitive layer 3 is difficult to soften even when the temperature in the image forming apparatus rises during image formation. When the softening of the photosensitive layer 3 is suppressed, the photosensitive layer 3 is less likely to be damaged, so that image defects in the formed image are less likely to occur. The glass transition point can be measured, for example, by the following method.

(Measurement method of glass transition point)
10 mg of the photosensitive layer 3 is taken out from the photoreceptor 1 and used as a sample for measuring the glass transition point. The glass transition point of the sample is measured using a differential scanning calorimeter (for example, “DSC-6220” manufactured by Seiko Instruments Inc.). A 10 mg sample is placed in an aluminum pan, and an empty aluminum pan is used as a reference. The measurement conditions are set to a measurement temperature range of 25 ° C. or more and 200 ° C. or less and a temperature increase rate of 10 ° C./min. The change point of the specific heat of the sample is obtained from the endothermic curve of the sample observed during the temperature rise. The glass transition point of the sample is determined from the obtained change point of specific heat.

[2-8. Additive]
The photosensitive layer 3 may contain various additives as long as the electrophotographic characteristics of the photoreceptor 1 are not adversely affected. Examples of additives include deterioration inhibitors (eg, antioxidants, radical scavengers, singlet quenchers, or ultraviolet absorbers), softeners, surface modifiers, extenders, thickeners, and dispersion stabilizers. Agents, waxes, acceptors, donors, surfactants, plasticizers, sensitizers, or leveling agents. Examples of the antioxidant include hindered phenol, hindered amine, paraphenylenediamine, arylalkane, hydroquinone, spirochroman, spiroidanone, or a derivative thereof, an organic sulfur compound, or an organic phosphorus compound.

[3. Middle layer]
In the photoreceptor 1, the intermediate layer 4 (particularly the undercoat layer) can be located between the conductive substrate 2 and the photosensitive layer 3. The intermediate layer 4 contains, for example, inorganic particles and a resin (interlayer resin) used for the intermediate layer 4. The presence of the intermediate layer 4 makes it possible to smooth the flow of current generated when the photosensitive member 1 is exposed while suppressing an increase in resistance while maintaining an insulating state capable of suppressing the occurrence of leakage.

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

The intermediate layer resin is not particularly limited as long as it is a resin that can be used as a resin for forming the intermediate layer 4.

The intermediate layer 4 may contain various additives as long as the electrophotographic characteristics of the photoreceptor 1 are not adversely affected. The additives are the same as those for the photosensitive layer 3.

[4. Photoconductor manufacturing method]
Next, a method for manufacturing the photoreceptor 1 will be described. The method for manufacturing the photoreceptor 1 can include a photosensitive layer forming step. In the photosensitive layer forming step, the photosensitive layer coating solution is applied onto the conductive substrate 2, and the solvent contained in the applied photosensitive layer coating solution is removed to form the photosensitive layer 3. The photosensitive layer coating solution may contain a polycarbonate resin, compound (I), one or more of compounds (II), (III), and (IV), and a solvent. The coating liquid for photosensitive layer can further contain a charge generating agent, an electron transporting agent, and various additives as necessary. The coating solution for the photosensitive layer can be prepared by dissolving or dispersing each component in a solvent.

The solvent contained in the photosensitive layer coating solution is not particularly limited as long as each component contained in the photosensitive layer coating solution can be dissolved or dispersed. Examples of the solvent include alcohols (for example, methanol, ethanol, isopropanol, or butanol), aliphatic hydrocarbons (for example, n-hexane, octane, or cyclohexane), aromatic hydrocarbons (for example, benzene, toluene, or Xylene), halogenated hydrocarbons (eg, dichloromethane, dichloroethane, carbon tetrachloride, or chlorobenzene), ethers (eg, dimethyl ether, diethyl ether, tetrahydrofuran, ethylene glycol dimethyl ether, or diethylene glycol dimethyl ether), ketones (eg, acetone, Methyl ethyl ketone or cyclohexanone), esters (for example, ethyl acetate or methyl acetate), dimethylformaldehyde, N, N-dimethylformamide (DM ), Or dimethyl sulfoxide. These solvents may be used alone or in combination of two or more. Of these solvents, solvents other than halogenated hydrocarbons (non-halogen-containing solvents) are preferable.

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

The photosensitive layer coating solution may contain, for example, a surfactant or a leveling agent in order to improve the dispersibility of each component or the surface smoothness of each layer formed.

The method for applying the photosensitive layer coating solution is not particularly limited as long as it is a method that can uniformly apply the photosensitive layer coating solution onto the conductive substrate 2. Examples of the coating method include a dip coating method, a spray coating method, a spin coating method, and a bar coating method.

The method for removing the solvent contained in the photosensitive layer coating solution is not particularly limited as long as it is a method capable of evaporating the solvent in the photosensitive layer coating solution. Examples of the method for removing the solvent include heating, reduced pressure, or combined use of heating and reduced pressure. More specifically, a method of performing heat treatment (hot air drying) using a high-temperature dryer or a vacuum dryer can be mentioned. The heat treatment conditions are, for example, a temperature of 40 ° C. or higher and 150 ° C. or lower and a time of 3 minutes or longer and 120 minutes or shorter.

In addition, the manufacturing method of the photoreceptor 1 may further include a step of forming the intermediate layer 4 and / or a step of forming the protective layer 5 as necessary. In the step of forming the intermediate layer 4 and the step of forming the protective layer 5, a known method can be appropriately selected.

The photoconductor 1 according to the first embodiment has been described above with reference to FIG. According to the photoreceptor 1 according to the first embodiment, the occurrence of toner filming can be suppressed.

[Second Embodiment: Image Forming Apparatus]
The second embodiment relates to the image forming apparatus 6. Hereinafter, the image forming apparatus 6 according to the present embodiment will be described with reference to FIG. FIG. 2 is a schematic diagram illustrating the configuration of the image forming apparatus 6.

The image forming apparatus 6 is not particularly limited as long as it is an electrophotographic image forming apparatus. The image forming apparatus 6 may be, for example, a monochrome image forming apparatus or a color image forming apparatus. The image forming apparatus 6 may be a tandem color image forming apparatus in order to form toner images of the respective colors using different color toners. Hereinafter, the image forming apparatus 6 will be described by taking a tandem color image forming apparatus as an example.

Further, the image forming apparatus 6 may be an image forming apparatus that employs an intermediate transfer method, or may be an image forming device that employs a direct transfer method. Hereinafter, the case where the image forming apparatus 6 adopts the intermediate transfer method will be described as an example.

The image forming apparatus 6 includes an image carrier corresponding to the photoreceptor 1, a charging unit 27, an exposure unit 28, a developing unit 29, and a transfer unit. The transfer unit corresponds to the primary transfer roller 33, the intermediate transfer belt 20, and the secondary transfer roller 21. As the image carrier, the photoreceptor 1 according to the first embodiment is provided.

The image forming apparatus 6 includes a plurality of photoreceptors 1 arranged in parallel in a predetermined direction and a plurality of developing units 29. Each of the plurality of developing units 29 is disposed to face the photoreceptor 1. Each of the plurality of developing units 29 includes a developing roller. The developing roller carries and conveys toner and supplies the toner to the surface of the corresponding photoreceptor 1.

As shown in FIG. 2, the image forming apparatus 6 further includes a box-shaped device housing 7. In the device housing 7, a paper feeding unit 8, an image forming unit 9, and a fixing unit 10 are provided. The paper feed unit 8 feeds the paper P. The image forming unit 9 transfers the toner image based on the image data to the paper P while conveying the paper P fed from the paper feeding unit 8. The fixing unit 10 fixes the unfixed toner image transferred on the paper P by the image forming unit 9 to the paper P. Further, a paper discharge unit 11 is provided on the upper surface of the device housing 7. The paper discharge unit 11 discharges the paper P fixed by the fixing unit 10.

The paper feed unit 8 includes a paper feed cassette 12, a first pickup roller 13,

paper feed rollers

14, 15, and 16, and a registration roller pair 17. The paper feed cassette 12 is provided so as to be detachable from the device housing 7. Various sizes of paper P are stored in the paper feed cassette 12. The first pickup roller 13 is provided at the upper left position of the paper feed cassette 12. The first pickup roller 13 takes out the sheets P stored in the sheet feeding cassette 12 one by one. The

paper feed rollers

14, 15 and 16 convey the paper P taken out by the first pickup roller 13. The registration roller pair 17 temporarily supplies the paper P conveyed by the

paper feed rollers

14, 15, and 16 to the image forming unit 9 at a predetermined timing.

The paper feed unit 8 further includes a manual feed tray (not shown) and a second pickup roller 18. The manual feed tray is attached to the left side surface of the device housing 7. The second pickup roller 18 takes out the paper P placed on the manual feed tray. The paper P taken out by the second pickup roller 18 is conveyed by the paper feed roller 16 and is supplied to the image forming unit 9 by the registration roller pair 17 at a predetermined timing.

The image forming unit 9 includes an image forming unit 19, an intermediate transfer belt 20, and a secondary transfer roller 21. A toner image is primarily transferred onto the intermediate transfer belt 20 by the image forming unit 19 on the surface of the intermediate transfer belt 20 (contact surface with the photoreceptor 1). The toner image to be primarily transferred is formed based on image data transmitted from a host device such as a computer. The secondary transfer roller 21 secondarily transfers the toner image on the intermediate transfer belt 20 onto the paper P fed from the paper feed cassette 12.

The image forming unit 19 includes a yellow toner supply unit 25 and a magenta toner supply from the upstream side (right side in FIG. 2) to the downstream side in the rotation direction of the intermediate transfer belt 20 with respect to the yellow toner supply unit 25 as a reference. A unit 24, a cyan toner supply unit 23, and a black toner supply unit 22 are sequentially arranged. In the

units

22, 23, 24, and 25, the photoreceptor 1 is disposed at the center position of each unit. The photoreceptor 1 is disposed so as to be rotatable in the direction of an arrow (clockwise).

Around each photoconductor 1, a charging unit 27, an exposure unit 28, a developing unit 29, and a primary transfer roller 33 are sequentially arranged from the upstream side in the rotation direction of each photoconductor 1 with respect to the charging unit 27.

The charging unit 27 charges the surface (peripheral surface) of the photoreceptor 1. Specifically, the charging unit 27 charges the peripheral surface of the photoreceptor 1 to positive polarity. The charging unit 27 is not particularly limited as long as the peripheral surface of the photoreceptor 1 can be charged. The charging unit 27 may be a non-contact method or a contact method. Examples of the charging unit 27 include a charging device, and more specifically, a corona charging device, a charging roller, or a charging brush. The charging unit 27 is preferably a contact-type charging device (specifically, a charging roller or a charging brush), and more preferably a charging roller.

The charging roller, for example, rotates depending on the rotation of the photoconductor 1 while in contact with the photoconductor 1. Examples of the charging roller include a charging roller having at least a surface portion made of a resin. Specifically, the charging roller includes a core metal that is rotatably supported, a resin layer formed on the core metal, and a voltage application unit that applies a voltage to the core metal. The charging unit 27 including such a charging roller can charge the surface of the photoreceptor 1 that is in contact with the resin through the resin layer when the voltage application unit applies a voltage to the cored bar.

The resin constituting the resin layer of the charging roller is not particularly limited as long as the peripheral surface of the photoreceptor 1 can be charged satisfactorily. Specific examples of the resin constituting the resin layer include a silicone resin, a urethane resin, or a silicone-modified resin. The resin layer may contain an inorganic filler.

It is considered that the discharge of active gas (for example, ozone or nitrogen oxide) generated from the charging unit 27 can be suppressed by using the contact type charging unit 27. As a result, it is considered that the deterioration of the photosensitive layer 3 due to the active gas is suppressed and the design considering the office environment can be achieved.

The voltage applied by the charging unit 27 is not particularly limited. Examples of the voltage applied by the charging unit 27 include a DC voltage, an AC voltage, and a superimposed voltage (a voltage obtained by superimposing an AC voltage on a DC voltage), and more preferably a DC voltage. The charging unit 27 that applies only a DC voltage has the following advantages compared to the charging unit 27 that applies an AC voltage or the charging unit 27 that applies a superimposed voltage obtained by superimposing an AC voltage on a DC voltage. When the charging unit 27 applies only a DC voltage, since the voltage value applied to the photoconductor 1 is constant, the surface of the photoconductor 1 is easily charged uniformly to a constant potential. Further, when the charging unit 27 applies only a DC voltage, the wear amount of the photosensitive layer 3 tends to decrease. As a result, a suitable image can be formed.

The voltage applied to the photosensitive member 1 by the charging unit 27 is preferably 1000 V or more and 2000 V or less, more preferably 1200 V or more and 1800 V or less, and particularly preferably 1400 V or more and 1600 V or less.

The exposure unit 28 exposes the surface of the charged photoconductor 1 to form an electrostatic latent image on the surface of the photoconductor 1. Specifically, the exposure unit 28 irradiates the peripheral surface of the photoreceptor 1 charged by the charging unit 27 with laser light based on image data input from a host device such as a personal computer. Thereby, an electrostatic latent image based on the image data is formed on the peripheral surface of the photoreceptor 1. Examples of the exposure unit 28 include an exposure device, and more specifically, a laser scanning unit.

The developing unit 29 develops the electrostatic latent image as a toner image. Specifically, the developing unit 29 supplies toner to the surface (peripheral surface) of the photoreceptor 1 on which the electrostatic latent image is formed, and forms a toner image based on the image data. An example of the developing unit 29 is a developing device.

The developing unit 29 can come into contact with the photoreceptor 1 when the developing unit 29 develops the electrostatic latent image as a toner image. The developing unit 29 can develop the electrostatic latent image formed on the surface of the photoreceptor 1 as a toner image while being in contact with the photoreceptor 1. The image forming apparatus 6 including the developing unit 29 is also referred to as a so-called “contact developing type image forming apparatus”. In the contact developing type image forming apparatus 6, the developing unit 29 can clean (remove) toner remaining on the surface of the photoreceptor 1 in addition to developing the electrostatic latent image as a toner image. . Since such a developing unit 29 also has a function as a cleaning unit, the image forming apparatus 6 can be configured not to include a single cleaning unit. The image forming apparatus 6 that does not include a single cleaning unit is also referred to as a so-called “cleanerless type image forming apparatus”.

In an image forming apparatus that employs a contact development method and / or a cleaner-less method, toner filming is likely to occur because the cleaning performance of the photoreceptor is usually reduced. However, the image forming apparatus 6 of this embodiment includes the photoreceptor 1 described above in the first embodiment. In the photoreceptor 1, the polycarbonate resin and the compound (I) included in the photosensitive layer 3 have a specific Vickers hardness. For this reason, when the developing unit 29 cleans (removes) the toner remaining on the surface of the photoreceptor 1, the contact area between the photoreceptor 1 and the toner tends to decrease. When the contact area between the photoreceptor 1 and the toner decreases, the toner remaining on the surface of the photoreceptor 1 can be easily scraped off by the developing unit 29. As a result, the cleaning property of the photosensitive member 1 is improved, and the occurrence of toner filming can be suppressed even when the image forming apparatus 6 adopts the contact development method and / or the cleaner-less method.

The image forming apparatus 6 adopting the contact development method and the cleaner-less method will be specifically described. The developing unit 29 provided in such an image forming apparatus 6 cleans components remaining on the surface of the photoreceptor 1 (hereinafter sometimes referred to as “residual components”). An example of the residual component is a toner component, and more specifically, a toner or a free external additive.

In order for the developing unit 29 to efficiently clean the surface of the photoreceptor 1, it is preferable to satisfy the following conditions (a) and (b).
Condition (a): A contact developing method is adopted, and a circumferential speed (rotational speed) difference is provided between the photosensitive member 1 and the developing unit 29.
Condition (b): The surface potential of the photoreceptor 1 and the potential of the developing bias satisfy the following expressions (b-1) and (b-2).
0 (V) <potential of developing bias (V) <surface potential of unexposed area of photoreceptor 1 (V) (b-1)
Development bias potential (V)> Surface potential (V) of exposed area of photoreceptor 1> 0 (V) (b-2)

When the contact development method shown in the condition (a) is adopted and a peripheral speed difference is provided between the photosensitive member 1 and the developing unit 29, the surface of the photosensitive member 1 comes into contact with the developing unit 29, and the photosensitive member 1 The adhering component on the surface is removed by friction with the developing unit 29. The peripheral speed of the developing unit 29 is preferably faster than the peripheral speed of the photoreceptor 1.

In condition (b), it is assumed that the development method is a reversal development method. It is preferable that the charging polarity of the toner, the surface potential of the unexposed area of the photoreceptor 1, the surface potential of the exposed area of the photoreceptor 1 and the potential of the developing bias are all positive. The surface potential of the unexposed area and the surface area of the exposed area of the photosensitive member 1 are determined such that the primary transfer roller 33 transfers the toner image from the photosensitive member 1 to the intermediate transfer belt 20 and then the charging unit 27 performs the next rotation. Measured before charging one surface.

When the mathematical expression (b-1) of the condition (b) is satisfied, the electrostatic force acting between the toner remaining on the photoreceptor 1 (hereinafter sometimes referred to as “residual toner”) and the unexposed area of the photoreceptor 1. The repulsive force is larger than the electrostatic repulsive force acting between the residual toner and the developing unit 29. Therefore, the residual toner in the unexposed area of the photoreceptor 1 moves from the surface of the photoreceptor 1 to the developing unit 29 and is collected.

When the mathematical expression (b-2) of the condition (b) is satisfied, the electrostatic repulsive force acting between the residual toner and the exposed area of the photosensitive member 1 acts on the electrostatic force acting between the residual toner and the developing unit 29. Smaller than the repulsive force. Therefore, the residual toner in the exposed area of the photoconductor 1 is held on the surface of the photoconductor 1. The toner held in the exposure area of the photoreceptor 1 is used as it is for image formation.

The transfer unit (corresponding to the primary transfer roller 33, the intermediate transfer belt 20, and the secondary transfer roller 21) transfers the toner image formed on the surface of the photoreceptor 1 onto the transfer target (corresponding to the paper P). Specifically, the primary transfer roller 33 transfers the toner image formed on the surface of the photoreceptor 1 to the intermediate transfer belt 20. The intermediate transfer belt 20 is an endless belt rotating body. The intermediate transfer belt 20 is stretched around a driving roller 30, a driven roller 31, a backup roller 32, and a plurality of primary transfer rollers 33. The intermediate transfer belt 20 is arranged such that the surfaces (circumferential surfaces) of the plurality of photoreceptors 1 abut on the surface of the intermediate transfer belt 20 (contact surface with the photoreceptor 1).

Further, the intermediate transfer belt 20 is pressed against the photoconductor 1 by a primary transfer roller 33 arranged to face each photoconductor 1. In the pressed state, the intermediate transfer belt 20 rotates endlessly in the arrow (counterclockwise) direction by the plurality of drive rollers 30. The driving roller 30 is rotationally driven by a driving source such as a stepping motor, and gives a driving force for rotating the intermediate transfer belt 20 endlessly. The driven roller 31, the backup roller 32, and the plurality of primary transfer rollers 33 are rotatably provided. The driven roller 31, the backup roller 32, and the primary transfer roller 33 rotate following the endless rotation of the intermediate transfer belt 20 by the driving roller 30. The driven roller 31, the backup roller 32, and the primary transfer roller 33 are driven to rotate via the intermediate transfer belt 20 according to the main rotation of the driving roller 30 and support the intermediate transfer belt 20.

The primary transfer roller 33 applies a primary transfer bias (specifically, a bias having a polarity opposite to the charging polarity of the toner) to the intermediate transfer belt 20. As a result, the toner image formed on each photoconductor 1 is sequentially transferred (primary transfer) to the intermediate transfer belt 20 that circulates between each photoconductor 1 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 paper P. As a result, the toner image primarily transferred onto the intermediate transfer belt 20 is transferred onto the paper P between the secondary transfer roller 21 and the backup roller 32. As a result, an unfixed toner image is transferred onto the paper P.

A cleaning device (not shown) and / or a static eliminator (not shown) may be provided on the upstream side of the charging unit 27 in the rotation direction of the photosensitive member 1 (downstream side of the primary transfer roller 33). The cleaning device cleans the toner remaining on the surface of the photoreceptor 1. The static eliminator neutralizes the peripheral surface of the photoreceptor 1 after the primary transfer of the toner image to the intermediate transfer belt 20 is completed. The peripheral surface of the photoreceptor 1 cleaned and discharged by the cleaning device and the charge eliminator is sent to the charging unit 27 and newly charged. When the image forming apparatus 6 includes a cleaning device and / or a static eliminator, the charging unit 27, the exposure unit 28, the developing unit 29, and the primary transfer roller 33 with respect to the charging unit 27 from the upstream side in the rotation direction of each photoconductor 1. , Cleaning device, and static eliminator.

The fixing unit 10 fixes the unfixed toner image transferred to the paper P by the image forming unit 9. The fixing unit 10 includes a heating roller 34 and a pressure roller 35. The heating roller 34 is heated by an energized heating element. The pressure roller 35 is disposed to face the heating roller 34, and the circumferential surface of the pressure roller 35 is pressed against the circumferential surface of the heating roller 34.

The transfer image transferred to the paper P by the secondary transfer roller 21 in the image forming unit 9 is fixed to the paper P by a fixing process by heating when the paper P passes between the heating roller 34 and the pressure roller 35. The Then, the paper P subjected to the fixing process is discharged to the paper discharge unit 11. In addition, a plurality of transport rollers 36 are disposed at appropriate positions between the fixing unit 10 and the paper discharge unit 11.

The paper discharge unit 11 is formed by recessing the top of the device housing 7. A paper discharge tray 37 that receives the discharged paper P is provided at the bottom of the recessed portion. The image forming apparatus 6 according to the present embodiment has been described above with reference to FIG.

As described with reference to FIG. 2, the image forming apparatus 6 according to the second embodiment includes the photosensitive member 1 according to the first embodiment as an image carrier. The photoreceptor 1 can suppress the occurrence of toner filming. Therefore, by providing such a photoreceptor 1, the image forming apparatus 6 according to the second embodiment can suppress the occurrence of image defects.

[Third embodiment: Process cartridge]
The third embodiment relates to a process cartridge. With continued reference to FIG. 2, the process cartridge according to the present embodiment will be described. The process cartridge corresponds to, for example, each of a yellow toner supply unit 25, a magenta toner supply unit 24, a cyan toner supply unit 23, and a black toner supply unit 22. The process cartridge includes the photoreceptor 1 according to the first embodiment as an image carrier. As described above in the first embodiment, the photoreceptor 1 can suppress the occurrence of toner filming. Therefore, when the process cartridge according to the present embodiment is provided in the image forming apparatus 6, it is considered that the occurrence of toner filming can be suppressed, and image defects caused thereby can be suppressed.

The process cartridge can include, for example, the photoreceptor 1 according to the first embodiment unitized as an image carrier. The process cartridge may be designed to be detachable from the image forming apparatus 6. In addition to the photoreceptor 1, the process cartridge can include at least one selected from the group consisting of a charging unit 27, an exposure unit 28, a developing unit 29, and a transfer unit (for example, a primary transfer roller 33). The process cartridge may further include a cleaning device and / or a static eliminator.

The process cartridge according to the third embodiment has been described above with reference to FIG. The process cartridge according to the third embodiment can suppress the occurrence of toner filming, and can suppress image defects caused thereby. Furthermore, since such a process cartridge is easy to handle, when the sensitivity characteristics of the photoconductor 1 deteriorate, the process cartridge including the photoconductor 1 can be easily and quickly replaced.

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

[1. Preparation of photoconductor]
Examples and comparisons using compound (I), one or more of compounds (II), (III), and (IV), compound (V), polycarbonate resin, and charge generator An example photoreceptor was prepared.

[1-1. Compound (I)]
For the preparation of the photoconductors (A-1) to (A-55), (B-1), and (B-2), the compound (1), ( 2), (3), or (4) was used. In the preparation of the photoreceptors (B-3) to (B-7), compounds represented by the chemical formulas (8) to (12) were used in place of the compound (I). Hereinafter, the compounds represented by the chemical formulas (8) to (12) may be referred to as compounds (8) to (12), respectively.

[1-2. Compounds (II), (III), and (IV)]
For the preparation of the photoreceptors (A-1) to (A-55) and (B-3) to (B-7), the compounds (II), (III), and (IV) are used in the first embodiment. One or more of the compounds (5), (6), and (7) described above were used.

[1-3. Compound (V)]
For the preparation of the photoreceptors (A-1) to (A-55) and (B-1) to (B-7), the compound (14) described in the first embodiment was used as the compound (V). It was.

[1-4. Polycarbonate resin]
For the preparation of the photoreceptors (A-1) to (A-55) and (B-1) to (B-7), a polycarbonate resin having a repeating unit represented by the chemical formula (Bis-Z) is used as a polycarbonate resin. Resin was used. Specifically, “Iupizeta PCZ-500” (viscosity average molecular weight: 50000) manufactured by Mitsubishi Gas Chemical Co., Ltd. was used.

[1-5. Charge generator]
In the preparation of the photoreceptors (A-1) to (A-55) and (B-1) to (B-7), metal-free phthalocyanine was used as a charge generator.

[1-6. Preparation of photoconductor (A-1)]
In the container, 50 parts by mass of compound (1), 30 parts by mass of compound (5), 20 parts by mass of compound (14), 100 parts by mass of polycarbonate resin, 3 parts by mass of charge generating agent, and tetrahydrofuran as a solvent 500 parts by mass were added. These were mixed and dispersed for 12 hours using a ball mill to prepare a coating solution for a photosensitive layer.

Using the dip coating method, the adjusted photosensitive layer coating solution was applied onto a conductive substrate to form a coating film on the conductive substrate. Then, it was made to dry for 60 minutes at 120 degreeC, and the solvent was removed from the coating film. As a result, a photoreceptor (A-1) according to Example 1 was obtained. In the photoreceptor (A-1), a photosensitive layer having a thickness of 30 μm was formed on a conductive substrate.

[1-7. Preparation of photoconductor other than photoconductor (A-1)]
Photoconductors (A-2) to (A-48) and (B-1) to (B-7) were prepared in the same manner as in the preparation of photoconductor (A-1), except for the following changes. Was prepared. 50 parts by mass of the compound (1) and 30 parts by mass of the compound (5) used for the preparation of the photoreceptor (A-1) were respectively used in the types and addition amounts of the compounds (I) shown in Tables 1 to 4 described later. As well as the type and amount of compound (II), (III), or (IV).

A photosensitive member (A-3) was prepared in the same manner as in the preparation of the photosensitive member (A-3) except that 20 parts by weight of the compound (5) and 10 parts by weight of the compound (6) were used instead of 30 parts by weight of the compound (5). A-49) was prepared.

A photoreceptor (A-3) was prepared in the same manner as in the preparation of the photoreceptor (A-3) except that 15 parts by weight of the compound (5) and 15 parts by weight of the compound (6) were used instead of 30 parts by weight of the compound (5). A-50) was prepared.

A photoreceptor (A-3) was prepared in the same manner as in the preparation of the photoreceptor (A-3) except that 10 parts by weight of the compound (5) and 20 parts by weight of the compound (6) were used instead of 30 parts by weight of the compound (5). A-51) was prepared.

A photosensitive member (A-3) was prepared in the same manner as in the preparation of the photosensitive member (A-3) except that 15 parts by weight of the compound (5) and 15 parts by weight of the compound (7) were used instead of 30 parts by weight of the compound (5). A-52) was prepared.

The photosensitive member (A-3) was prepared in the same manner as in the preparation of the photosensitive member (A-3) except that 15 parts by weight of the compound (6) and 15 parts by weight of the compound (7) were used instead of 30 parts by weight of the compound (5). A-53) was prepared.

Preparation of the photoreceptor (A-3) was conducted except that 10 parts by weight of the compound (5), 10 parts by weight of the compound (6) and 10 parts by weight of the compound (7) were used instead of 30 parts by weight of the compound (5). A photoconductor (A-54) was prepared in the same manner.

Preparation of the photoreceptor (A-38) except that 20 parts by weight of the compound (5), 5 parts by weight of the compound (6) and 5 parts by weight of the compound (7) were used instead of 30 parts by weight of the compound (5). A photoconductor (A-55) was prepared in the same manner.

[2. Measurement of Vickers hardness]
For the photoreceptors (A-1) to (A-15), the Vickers hardness of the polycarbonate resin and the compound (1) was measured as follows. First, 30 parts by mass of the compound (1) and 100 parts by mass of the polycarbonate resin were charged into the container. The contents of the container were mixed and dispersed at 30 ° C. for 1 hour using a disperser (“Precision Emulsion Disperser CLEAMIX (registered trademark) CLM-1.5S” manufactured by M Technique Co., Ltd.). The dispersion was obtained by curing at 60 ° C. for 60 minutes. The thickness of the obtained dispersion was 27.5 μm (error range: ± 4.5 μm).

The Vickers hardness of the obtained dispersion was measured by a method in accordance with Japanese Industrial Standard (JIS Z2244). For the measurement of Vickers hardness, a hardness meter (for example, “Micro Vickers hardness meter DMH-1 type” manufactured by Matsuzawa Co., Ltd. (formerly Matsuzawa Seiki Co., Ltd.)) was used. The Vickers hardness is measured at a temperature of 23 ° C., a diamond indenter load (test force) of 10 gf, a time required to reach the test force of 5 seconds, a diamond indenter approach speed of 2 mm / second, and a test force holding time of 1 second. Performed under conditions.

Regarding the photoconductors (A-16) to (A-55) and (B-1) to (B-7), the photoconductors (A-1) to (A-15) and Similarly, Vickers hardness was measured. 30 parts by mass of the compound (1) to be charged into the container are each compound (I) of the type shown in Tables 1 to 4 (specifically, compound (1), (2), (3), or (4) ) Or a compound added instead of compound (I) (specifically, compound (8), (9), (10), (11), or (12)) was changed to 30 parts by mass.

Table 1 to Table 4 show the measured Vickers hardness.

[3. Melting point measurement]
About each of compound (1), (2), (3), and (4) used as compound (I), melting | fusing point (Mp) was measured with the following method. Further, the melting point of each of the compounds (8), (9), (10), (11), and (12) added in place of the compound (I) was measured by the following method.

The melting point of each compound was measured using a differential scanning calorimeter (“DSC-6220” manufactured by Seiko Instruments Inc.). After putting 10 mg sample (compound (1), (2), (3), (4), (8), (9), (10), (11), or (12)) in an aluminum dish, An aluminum dish was set in the measurement part of the DSC. An empty aluminum dish was used as a reference. The sample was heated to 170 ° C. at a rate of 10 ° C./min with 30 ° C. as the measurement start temperature. The maximum peak temperature of the heat of fusion observed when the temperature was raised was taken as the melting point of the sample.

Tables 1 to 4 show the measured melting points of the respective compounds.

[4. Measurement of glass transition point]
10 mg of the photosensitive layer was taken out from each of the photoreceptors (A-1) to (A-55) and (B-1) to (B-7). 10 mg of the extracted photosensitive layer was used as a sample for measuring the glass transition point (Tg).

The glass transition point of each sample obtained was measured using a differential scanning calorimeter (“DSC-6220” manufactured by Seiko Instruments Inc.). A 10 mg sample was placed in an aluminum pan, and an empty aluminum pan was used as a reference. The measurement conditions were set to a measurement temperature range of 25 ° C. or more and 200 ° C. or less and a temperature increase rate of 10 ° C./min. The change point of the specific heat of the sample was determined from the endothermic curve of the sample observed during the temperature rise. The glass transition point of the sample was determined from the obtained specific heat change point.

Tables 1 to 4 show the measured glass transition points of the respective photosensitive layers.

[5. Evaluation of toner filming resistance]
Any one of the photoconductors (A-1) to (A-55) and (B-1) to (B-7) is converted into an image forming apparatus (“monochrome printer FS-1300D” manufactured by Kyocera Document Solutions Inc.) ). This image forming apparatus employs a contact development method and a cleaner-less method. In this image forming apparatus, the developing unit cleans the toner remaining on the photoreceptor. Using this image forming apparatus, images (printing rate of 1%) are printed on paper (Kyocera Document Solutions Brand “VM-A4”, A4 size, sold by Kyocera Document Solutions Co., Ltd.) on the condition that the rotational speed of the photosensitive member is 168 mm / second 20,000 sheets were continuously printed. Printing was performed in an environment of a temperature of 35 ° C. and a humidity of 85% RH. A one-component developer (prototype) was used for printing.

After the printing, the photoreceptor was taken out from the image forming apparatus, and the degree of toner filming on the photoreceptor surface was observed. Specifically, the surface of the photoreceptor was observed at a magnification of 50 using an optical microscope (“Sennar KK” manufactured by Nikon Corporation) to obtain an observation image. The pixels constituting the obtained observation image each had a luminance value of 0 or more and 255 or less. Using the image analysis software (Image J), the observed image was binarized with a luminance value of 180 as a threshold value. A pixel having a luminance value less than the threshold corresponds to a region where toner filming has occurred. On the other hand, a pixel having a luminance value equal to or higher than the threshold corresponds to a region where toner filming has not occurred.

By binarization processing, the area (At) of the region where toner filming occurred and the area (An) of the region where toner filming did not occur were obtained. From the obtained At and An, the area ratio (A) of the region where toner filming occurred was obtained according to the calculation formula 1.
Area ratio A [%] = 100 × At / (At + An) (Formula 1)

The area ratio A was determined by the above-described method at the following three locations on the photoreceptor.
Measurement location 1: Center portion of the photoconductor Measurement location 2: Location moved 20 mm from the upper end surface in the direction from the upper end surface to the lower end surface of the photoconductor Measurement location 3: Lower end surface in the direction from the lower end surface to the upper end surface of the photoconductor The area ratios A obtained for the measurement points 1, 2 and 3 moved 20 mm from the area were defined as area ratios A1, A2 and A3, respectively. The average value “(A1 + A2 + A3) / 3” of the area ratios A1, A2, and A3 was used as the evaluation result of the toner filming resistance. Tables 1 to 4 show the evaluation results (area ratio) of the toner filming resistance.

The smaller the area ratio, the less the toner filming on the photoreceptor surface. For example, when the area ratio is 1.00% or less, it is difficult for an image defect to appear in the formed image.

In Tables 1 to 4, “Hardness” indicates the Vickers hardness of the polycarbonate resin and the compound (I) or the Vickers hardness of the polycarbonate and the compound added instead of the compound (I). “Tg” indicates a glass transition point. “Compound types” 1 to 12 represent compounds (1) to (12), respectively. In Table 4, “5/6”, “5/7”, “6/7” and “5/6/7” indicate that the compounds (5) and (6) were used, the compound (5) and It shows that (7) was used, that compounds (6) and (7) were used, and that compounds (5), (6) and (7) were used. In Table 4, when the addition amount is shown using “/”, the addition amount of each corresponding compound is shown.

As shown in Tables 1 to 4, the photoreceptors (A-1) to (A-55) include polycarbonate resin, compound (I), compound (II), compound (III), and compound (IV). One or more of them were contained. Furthermore, the Vickers hardness of polycarbonate resin and compound (I) was 16.0HV or more. Therefore, in these photoreceptors, the area ratio is 1.00% or less, and the occurrence of toner filming is suppressed.

On the other hand, the photoreceptors (B-1) and (B-2) did not contain any of the compound (II), the compound (III), and the compound (IV). The photoreceptors (B-3), (B-4), (B-6) and (B-7) do not contain the compound (I), and the Vickers hardness between the polycarbonate resin and the compound (I) Was less than 16.0 HV. The photoreceptor (B-5) did not contain compound (I). Therefore, in these photoreceptors, the area ratio exceeds 1.00%, and toner filming has occurred.

From the above, it has been shown that the photoreceptor according to the present invention suppresses the occurrence of toner filming. Further, it has been shown that an image forming apparatus provided with such a photoreceptor suppresses toner filming.

The photoreceptor according to the present invention can be suitably used as an electrophotographic photoreceptor.

Claims

A positively charged single layer type electrophotographic photosensitive member provided with a photosensitive layer,
The photosensitive layer comprises a polycarbonate resin, a compound represented by the following general formula (I), and one or more compounds selected from the following general formulas (II), (III), and (IV). Contains,
The Vickers hardness of the polycarbonate resin and the compound represented by the general formula (I) is 16.0 HV or more,
The Vickers hardness is obtained by measuring a dispersion in which 30 parts by mass of the compound represented by the general formula (I) is dispersed with respect to 100 parts by mass of the polycarbonate resin. Photoconductor.

In the general formula (I),
R 1 , R 2 , R 3 , R 4 , R 5 , and R 6 each independently represent a hydrogen atom, an alkyl group, or an alkoxy group,
One or more of R 1 , R 2 , and R 3 are an alkyl group or an alkoxy group;
One or more of R 4 , R 5 , and R 6 is an alkyl group or an alkoxy group.

In the general formula (II),
R 21 and R 22 are each independently a substituent selected from the group consisting of an alkyl group, an alkoxy group and a halogen atom, which may have a substituent selected from the group consisting of an alkoxy group and a halogen atom. Or an aryl group which may have a substituent selected from the group consisting of an alkyl group, an alkoxy group and a halogen atom, R 21 and R 22 are different from each other;
R 23 , R 24 and R 25 are each independently a group consisting of an alkyl group, an alkoxy group and a halogen atom which may have a substituent selected from the group consisting of a hydrogen atom, an alkoxy group and a halogen atom. Represents an alkoxy group which may have a substituent selected from: or an aryl group which may have a substituent selected from the group consisting of an alkyl group, an alkoxy group and a halogen atom;
R 26 and R 27 each independently represents a hydrogen atom, an alkyl group, an alkoxy group, or a halogen atom.

In the general formula (III),
R 31 and R 32 are each independently a substituent selected from the group consisting of an alkyl group, an alkoxy group and a halogen atom, which may have a substituent selected from the group consisting of an alkoxy group and a halogen atom. Or an aryl group which may have a substituent selected from the group consisting of an alkyl group, an alkoxy group and a halogen atom, R 31 and R 32 are different from each other;
R 33 , R 34 and R 35 are each independently a group consisting of an alkyl group, an alkoxy group and a halogen atom which may have a substituent selected from the group consisting of a hydrogen atom, an alkoxy group and a halogen atom. Represents an alkoxy group which may have a substituent selected from: or an aryl group which may have a substituent selected from the group consisting of an alkyl group, an alkoxy group and a halogen atom;
R 36 represents a hydrogen atom, an alkyl group, an alkoxy group, or a halogen atom.

In the general formula (IV),
R 41 , R 42 , R 43 , R 44 and R 45 are each independently an alkyl group or an alkoxy group which may have a substituent selected from the group consisting of a hydrogen atom, an alkoxy group and a halogen atom And an alkoxy group which may have a substituent selected from the group consisting of halogen atoms, or an aryl group which may have a substituent selected from the group consisting of alkyl groups, alkoxy groups and halogen atoms,
R 46 , R 47 , R 48 , and R 49 represent a hydrogen atom, an alkyl group, an alkoxy group, or a halogen atom.
In the general formula (I),
R 1 , R 2 , R 3 , R 4 , R 5 , and R 6 are each independently a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms. Represents
One or more of R 1 , R 2 , and R 3 are an alkyl group having 1 to 6 carbon atoms or an alkoxy group having 1 to 6 carbon atoms;
One or more of R 4 , R 5 , and R 6 are an alkyl group having 1 to 6 carbon atoms or an alkoxy group having 1 to 6 carbon atoms;
In the general formula (II),
R 21 and R 22 each independently represents an alkyl group having 1 to 6 carbon atoms, and R 21 and R 22 are different from each other;
R 23 , R 24 , and R 25 represent a hydrogen atom,
R 26 and R 27 represent a hydrogen atom,
In the general formula (III),
R 31 and R 32 each independently represents an alkyl group having 1 to 6 carbon atoms, and R 31 and R 32 are different from each other;
R 33 , R 34 , and R 35 represent a hydrogen atom,
R 36 represents a hydrogen atom,
In the general formula (IV),
R 41 , R 42 , R 43 , R 44 , and R 45 each independently represent a hydrogen atom or an alkyl group having 1 to 6 carbon atoms,
The positively charged single layer type electrophotographic photosensitive member according to claim 1, wherein R 46 , R 47 , R 48 , and R 49 represent a hydrogen atom.
The positively charged single layer type electrophotographic photosensitive member according to claim 1, wherein the melting point of the compound represented by the general formula (I) is 170 ° C. or less.
The positively charged single layer type electrophotographic photosensitive member according to claim 1, wherein the photosensitive layer has a glass transition point of 60.0 ° C or higher.
The positively charged single layer type electrophotographic image according to claim 1, wherein the content of the compound represented by the general formula (I) is 10 parts by mass or more and 150 parts by mass or less with respect to 100 parts by mass of the polycarbonate resin. Photoconductor.
The total content of one or more of the compounds represented by the general formulas (II), (III), and (IV) is 10 parts by mass or more and 60 parts by mass or less with respect to 100 parts by mass of the polycarbonate resin. The positively charged single layer type electrophotographic photosensitive member according to claim 1, wherein
The positively charged single layer type electrophotographic photosensitive member according to claim 1, wherein the photosensitive layer contains two or more of the compounds represented by the general formulas (II), (III), and (IV). .
The positively charged single layer type electrophotographic photosensitive member according to claim 1, wherein the photosensitive layer further contains a compound represented by the following general formula (V).

In the general formula (V), R 11 , R 12 , R 13 , and R 14 each independently represents an alkyl group, an aryl group, or an alkoxy group.
9. The positively charged monolayer according to claim 8, wherein, in the general formula (V), R 11 , R 12 , R 13 , and R 14 each independently represents an alkyl group having 1 to 6 carbon atoms. Type electrophotographic photoreceptor.
The positively charged single layer type electrophotographic photosensitive member according to claim 1, further comprising a conductive substrate, wherein the photosensitive layer further contains a charge generating agent.
A process cartridge comprising the positively charged single layer type electrophotographic photosensitive member according to claim 1.
An image carrier;
A charging unit that charges the surface of the image carrier;
An exposure unit that exposes the surface of the charged image carrier to form an electrostatic latent image on the surface of the image carrier;
A developing unit for developing the electrostatic latent image as a toner image;
An image forming apparatus comprising: a transfer unit that transfers the toner image from the image carrier to a transfer target;
The image forming apparatus according to claim 1, wherein the image carrier is the positively charged single layer type electrophotographic photosensitive member according to claim 1.
13. The image forming apparatus according to claim 12, wherein when the developing unit develops the electrostatic latent image as the toner image, the developing unit is in contact with the image carrier.
13. The image forming apparatus according to claim 12, wherein the developing unit cleans toner remaining on the surface of the image carrier in addition to the development.