JP2020181014A - Electrophotographic photoreceptor - Google Patents

Abstract

To provide an electrophotographic photoreceptor that is excellent in wear resistance and can prevent the occurrence of an image defect caused by light exposure and an image defect caused by contact with a member provided in an image forming apparatus.SOLUTION: A photosensitive layer 3 provided in an electrophotographic photoreceptor 1 contains a charge generating agent, a hole transport agent, a binder resin, and an azo compound. The binder resin contains a polyarylate resin. The polyarylate resin includes a repeating unit represented by a specific general formula and a repeating unit represented by a specific chemical formula. The ratio of the number n1 of the repeating units represented by a specific general formula to the number n2 of the repeating units represented by a specific chemical formula, n1/n2 is 1.0 or more. The azo compound is represented by the general formula (10).SELECTED DRAWING: Figure 1

Description

The present invention relates to an electrophotographic photosensitive member.

The electrophotographic photosensitive member is used as an image carrier in an electrophotographic image forming apparatus (for example, a printer or a multifunction device). The electrophotographic photosensitive member includes a photosensitive layer. As the electrophotographic photosensitive member, for example, a single-layer electrophotographic photosensitive member and a laminated electrophotographic photosensitive member are used. The single-layer electrophotographic photosensitive member includes a single-layer photosensitive layer having a function of generating charges and a function of transporting charges. The laminated electrophotographic photosensitive member includes a photosensitive layer including a charge generating layer having a charge generating function and a charge transporting layer having a charge transporting function.

Patent Document 1 describes an electrophotographic photosensitive member having a photosensitive layer. The binder resin of this photosensitive layer is a polyarylate resin containing a structure represented by the following chemical formula.

Japanese Unexamined Patent Publication No. 2003-322982

However, according to the studies by the present inventors, it has been found that the image-forming member described in Patent Document 1 is insufficient in terms of wear resistance.

The present invention has been made in view of the above problems, and an object of the present invention is to suppress the occurrence of image defects due to light exposure and image defects due to contact with a member of an image forming apparatus. It is to provide an electrophotographic photosensitive member that can be used.

The electrophotographic photosensitive member of the present invention includes a conductive substrate and a photosensitive layer. The photosensitive layer contains a charge generator, a hole transport agent, a binder resin, and an azo compound. The binder resin contains a polyarylate resin. The polyarylate resin contains a repeating unit represented by the general formula (1), a repeating unit represented by the chemical formula (2), and a repeating unit represented by the chemical formula (3). The ratio n ₁ / n ₂ of the number n ₁ of the repeating units represented by the general formula (1) to the number n ₂ of the repeating units represented by the chemical formula (2) is 1.0 or more. The azo compound is represented by the general formula (10).

In the general formula (1), R ¹ and R ² independently represent a hydrogen atom or a methyl group, R ³ represents a methyl group, and R ⁴ represents a hydrogen atom or an alkyl group having 2 or 3 carbon atoms. Represent. Alternatively, R ¹ and R ² represent a methyl group, respectively, and R ³ and R ⁴ bond with each other to represent a cycloalkylidene group having 5 or 6 carbon atoms.

In the general formula (10), R ¹¹ and R ¹² each independently represent an alkyl group having 1 or more and 3 or less carbon atoms. Ar ¹ and Ar ² each independently represent an arylene group having 6 to 14 carbon atoms which may be substituted with at least one substituent. The substituent is selected from the group consisting of an alkyl group having 1 or more and 3 or less carbon atoms and an alkoxy group having 1 or more and 3 or less carbon atoms. Q represents a monovalent group represented by the general formula (Q1) or (Q2).

In the general formula (Q1), Ar ³ and Ar ⁴ each independently represent an aryl group having 6 to 14 carbon atoms which may be substituted with an alkyl group having 1 or more and 3 or less carbon atoms. In the general formula (Q2), Z represents a heterocycle having at least 6 or more and 18 or less members having a nitrogen atom as a ring-constituting atom.

The electrophotographic photosensitive member of the present invention has excellent abrasion resistance, and can suppress the occurrence of image defects due to light exposure and image defects due to contact with a member included in the image forming apparatus.

It is a partial cross-sectional view of the laminated electrophotographic photosensitive member which is an example of the electrophotographic photosensitive member which concerns on embodiment of this invention. It is a partial cross-sectional view of the laminated electrophotographic photosensitive member which is an example of the electrophotographic photosensitive member which concerns on embodiment of this invention. It is a partial cross-sectional view of the laminated electrophotographic photosensitive member which is an example of the electrophotographic photosensitive member which concerns on embodiment of this invention. It is a partial cross-sectional view of the single-layer type electrophotographic photosensitive member which is an example of the electrophotographic photosensitive member which concerns on embodiment of this invention. It is a partial cross-sectional view of the single-layer type electrophotographic photosensitive member which is an example of the electrophotographic photosensitive member which concerns on embodiment of this invention. It is a partial cross-sectional view of the single-layer type electrophotographic photosensitive member which is an example of the electrophotographic photosensitive member which concerns on 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 carried out with appropriate modifications within the scope of the object of the present invention. In addition, although the description may be omitted as appropriate for the parts where the description is duplicated, the gist of the invention is not limited. Hereinafter, the compound and its derivative may be collectively referred to by adding "system" after the compound name. Further, when the polymer name is represented by adding "system" after the compound name, it means that the repeating unit of the polymer is derived from the compound or its derivative.

First, the substituents used in the present specification will be described. Alkyl groups with 1 to 8 carbon atoms, alkyl groups with 1 to 6 carbon atoms, alkyl groups with 1 to 3 carbon atoms, alkyl groups with 2 carbon atoms, and alkyl groups with 3 carbon atoms are , Each is linear or branched and unsubstituted, unless otherwise specified. Examples of the alkyl group having 1 or more carbon atoms and 8 or less carbon atoms include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, a tert-butyl group, an n-pentyl group, and 1 -Methylbutyl group, 2-methylbutyl group, 3-methylbutyl group, 1-ethylpropyl group, 2-ethylpropyl group, 1,1-dimethylpropyl group, 1,2-dimethylpropyl group, 2,2-dimethylpropyl group, 1,2-dimethylpropyl group, n-hexyl group, 1-methylpentyl group, 2-methylpentyl group, 3-methylpentyl group, 4-methylpentyl group, 1,1-dimethylbutyl group, 1,2-dimethyl Butyl group, 1,3-dimethylbutyl group, 2,2-dimethylbutyl group, 2,3-dimethylbutyl group, 3,3-dimethylbutyl group, 1,1,2-trimethylpropyl group, 1,2,2 Included are -trimethylpropyl group, 1-ethylbutyl group, 2-ethylbutyl group and 3-ethylbutyl group, linear and branched heptyl groups, and linear and branched octyl groups. Examples of alkyl groups having 1 to 6 carbon atoms, alkyl groups having 1 to 3 carbon atoms, alkyl groups having 2 carbon atoms, and alkyl groups having 3 carbon atoms have 1 to 8 carbon atoms, respectively. Among the groups described as examples of the following alkyl groups, the group has a corresponding number of carbon atoms.

Unless otherwise specified, the alkoxy group having 1 or more and 8 or less carbon atoms and the alkoxy group having 1 or more and 3 or less carbon atoms are linear or branched and unsubstituted. Examples of the alkoxy group having 1 or more carbon atoms and 8 or less carbon atoms include a methoxy group, an ethoxy group, an n-propoxy group, an isopropoxy group, an n-butoxy group, a sec-butoxy group, a tert-butoxy group and an n-pentoxy group. 1-Methylbutoxy group, 2-Methylbutoxy group, 3-Methylbutoxy group, 1-ethylpropoxy group, 2-ethylpropoxy group, 1,1-dimethylpropoxy group, 1,2-dimethylpropoxy group, 2,2- Dimethylpropoxy group, 1,2-dimethylpropoxy group, n-hexyloxy group, 1-methylpentyloxy group, 2-methylpentyloxy group, 3-methylpentyloxy group, 4-methylpentyloxy group, 1,1- Dimethylbutoxy group, 1,2-dimethylbutoxy group, 1,3-dimethylbutoxy group, 2,2-dimethylbutoxy group, 2,3-dimethylbutoxy group, 3,3-dimethylbutoxy group, 1,1,2- Methyl propoxy group, 1,2,2-trimethylpropoxy group, 1-ethylbutoxy group, 2-ethylbutoxy group, 3-ethylbutoxy group, linear and branched heptyloxy group, and linear and branched Examples include branched octyloxy groups. An example of an alkoxy group having 1 or more and 3 or less carbon atoms is a group having a corresponding carbon atom number among the groups described as an example of an alkoxy group having 1 or more and 8 or less carbon atoms.

Aryl groups having 6 to 14 carbon atoms are unsubstituted unless otherwise specified. Examples of the aryl group having 6 to 14 carbon atoms include a phenyl group, a naphthyl group, an indasenyl group, a biphenylenyl group, an acenaphthylenyl group, an anthryl group, and a phenanthryl group.

Cycloalkanes having 5 or more and 7 or less carbon atoms are unsubstituted unless otherwise specified. Examples of cycloalkanes having 5 or more and 7 or less carbon atoms include cyclopentane, cyclohexane, and cycloheptane.

Heterocycles of 6 to 18 members and heterocycles of 13 to 15 members are unsubstituted unless otherwise specified. These heterocycles may have at least a nitrogen atom as a ring-constituting atom, and may further have an oxygen atom and a carbon atom. Examples of heterocycles having 6 or more and 18 or less members include carbazole, indole, isoindole, indazole, quinoline, isoquinoline, cinnoline, quinazoline, quinoxaline, phthalazine, purine, pteridine, phenanthridine, aclysine, phenazine, phenanthridine, and chemical formula. Examples thereof include a heterocycle represented by (HC-1) and a heterocycle represented by the chemical formula (HC-2). An example of a heterocycle having 13 or more members and 15 members or less is a group having a corresponding number of ring members among the heterocycles described as an example of a heterocycle having 6 members or more and 18 members or less. The substituents used in the present specification have been described above.

<Electrophotophotoreceptor>
The present embodiment relates to an electrophotographic photosensitive member (hereinafter, may be referred to as a photosensitive member). The photoconductor of this embodiment includes a conductive substrate and a photosensitive layer. The photosensitive layer contains a charge generator, a hole transport agent, a binder resin, and an azo compound. The photoconductor is, for example, a single-layer electrophotographic photosensitive member (hereinafter, may be referred to as a single-layer type photosensitive member) or a laminated electrophotographic photosensitive member (hereinafter, may be referred to as a laminated type photosensitive member). Is.

(Laminated photoconductor)
Next, the laminated photoconductor 1 as an example of the photoconductor will be described with reference to FIGS. 1 to 3. 1 to 3 show partial cross-sectional views of the laminated photoconductor 1, respectively.

As shown in FIG. 1, the laminated photoconductor 1 includes, for example, a conductive substrate 2 and a photosensitive layer 3. The photosensitive layer 3 includes a charge generation layer 3a and a charge transport layer 3b. That is, the laminated photoconductor 1 includes a charge generation layer 3a and a charge transport layer 3b as the photosensitive layer 3. The charge generation layer 3a is, for example, a single layer. The charge transport layer 3b is, for example, a single layer.

As shown in FIG. 1, in the laminated photoconductor 1, a charge generation layer 3a may be provided on the conductive substrate 2, and a charge transport layer 3b may be provided on the charge generation layer 3a. Alternatively, as shown in FIG. 2, in the laminated photoconductor 1, a charge transport layer 3b may be provided on the conductive substrate 2 and a charge generation layer 3a may be provided on the charge transport layer 3b.

As shown in FIG. 3, the laminated photoconductor 1 may include a conductive substrate 2, a photosensitive layer 3, and an intermediate layer 4 (undercoat layer). The intermediate layer 4 is provided between the conductive substrate 2 and the photosensitive layer 3. As shown in FIGS. 1 and 2, in the laminated photoconductor 1, the photosensitive layer 3 may be provided directly on the conductive substrate 2. Alternatively, as shown in FIG. 3, in the laminated photoconductor 1, the photosensitive layer 3 may be provided on the conductive substrate 2 via the intermediate layer 4. When the laminated photoconductor 1 includes the intermediate layer 4, as shown in FIG. 3, the intermediate layer 4 is provided on the conductive substrate 2, the charge generation layer 3a is provided on the intermediate layer 4, and the charge generation layer 3a is provided. A charge transport layer 3b may be provided on top. Alternatively, the intermediate layer 4 may be provided on the conductive substrate 2, the charge transport layer 3b may be provided on the intermediate layer 4, and the charge generation layer 3a may be provided on the charge transport layer 3b.

The laminated photoconductor 1 may include a conductive substrate 2, a photosensitive layer 3, and a protective layer 5 (see FIG. 6). The protective layer 5 is provided on the photosensitive layer 3. As shown in FIGS. 1 and 2, the photosensitive layer 3 (for example, the charge transport layer 3b or the charge generating layer 3a) may be provided as the outermost surface layer of the laminated photoconductor 1. Alternatively, the protective layer 5 may be provided as the outermost surface layer of the laminated photoconductor 1.

As shown in FIG. 1, it is preferable that the photosensitive layer 3 (more specifically, the charge transport layer 3b) is provided as the outermost surface layer of the laminated photoconductor 1. It is more preferable that the charge transport layer 3b is a single layer and is provided as the outermost surface layer of the laminated photoconductor 1. By providing the charge transport layer 3b containing the polyarylate resin (PA) described later and a predetermined azo compound as the outermost surface layer, the wear resistance of the laminated photoconductor 1 is further improved, which is caused by light exposure. It is possible to further suppress the occurrence of image defects and image defects caused by contact with a member included in the image forming apparatus.

The charge generating layer 3a contains a charge generating agent. The charge generation layer 3a may contain a base resin. The charge generation layer 3a may contain an additive, if necessary. The thickness of the charge generation layer 3a is not particularly limited, but is preferably 0.01 μm or more and 5 μm or less, and more preferably 0.1 μm or more and 3 μm or less.

The charge transport layer 3b contains a hole transport agent, a binder resin, and an azo compound. The charge transport layer 3b may further contain an additive, if necessary. The thickness of the charge transport layer 3b is not particularly limited, but is preferably 2 μm or more and 100 μm or less, and more preferably 5 μm or more and 50 μm or less. The laminated photoconductor 1 has been described above with reference to FIGS. 1 to 3.

(Single-layer photoconductor)
Next, the single-layer type photoconductor 10 which is an example of the photoconductor will be described with reference to FIGS. 4 to 6. 4 to 6 show partial cross-sectional views of the single-layer type photoconductor 10.

As shown in FIG. 4, the single-layer photoconductor 10 includes, for example, a conductive substrate 2 and a photosensitive layer 3. The photosensitive layer 3 provided in the single-layer type photosensitive member 10 is a single layer. Hereinafter, the "single-layer photosensitive layer 3" may be referred to as a "single-layer photosensitive layer 3c".

As shown in FIG. 5, the single-layer type photosensitive member 10 may include a conductive substrate 2, a single-layer type photosensitive layer 3c, and an intermediate layer 4 (undercoat layer). The intermediate layer 4 is provided between the conductive substrate 2 and the single-layer photosensitive layer 3c. As shown in FIG. 4, the single-layer photosensitive layer 3c may be provided directly on the conductive substrate 2. Alternatively, as shown in FIG. 5, the single-layer photosensitive layer 3c may be provided on the conductive substrate 2 via the intermediate layer 4.

As shown in FIG. 6, the single-layer photosensitive member 10 may include a conductive substrate 2, a single-layer photosensitive layer 3c, and a protective layer 5. The protective layer 5 is provided on the single-layer photosensitive layer 3c. As shown in FIGS. 4 and 5, the single-layer type photosensitive layer 3c may be provided as the outermost surface layer of the single-layer type photosensitive member 10. Alternatively, as shown in FIG. 6, the protective layer 5 may be provided as the outermost surface layer of the single-layer type photoconductor 10.

As shown in FIGS. 4 and 5, it is preferable that the photosensitive layer 3 (more specifically, the single-layer type photosensitive layer 3c) is provided as the outermost surface layer of the single-layer type photosensitive member 10. By providing the single-layer type photosensitive layer 3c containing the polyarylate resin (PA) described later and a predetermined azo compound as the outermost surface layer, the wear resistance of the single-layer type photosensitive member 10 is further improved, and light exposure is achieved. It is possible to further suppress the occurrence of image defects due to the above and the occurrence of image defects due to contact with the member included in the image forming apparatus.

The single-layer photosensitive layer 3c contains a charge generator, a hole transport agent, a binder resin, and an azo compound. The single-layer photosensitive layer 3c may further contain an electron transporting agent. The single-layer photosensitive layer 3c may contain an additive, if necessary.

The thickness of the single-layer photosensitive layer 3c is not particularly limited, but is preferably 5 μm or more and 100 μm or less, and more preferably 10 μm or more and 50 μm or less. The single-layer photoconductor 10 has been described above with reference to FIGS. 4 to 6.

(Binder resin)
The photosensitive layer contains a polyarylate resin as a binder resin. The polyarylate resin contains a repeating unit represented by the general formula (1), a repeating unit represented by the chemical formula (2), and a repeating unit represented by the chemical formula (3). The ratio n ₁ / n ₂ of the number n ₁ of the repeating units represented by the general formula (1) to the number n ₂ of the repeating units represented by the chemical formula (2) is 1.0 or more.

In the general formula (1), R ¹ and R ² each independently represent a hydrogen atom or a methyl group, R ³ represents a methyl group, and R ⁴ represents a hydrogen atom or an alkyl group having 2 or 3 carbon atoms. Represent. Alternatively, in the general formula (1), R ¹ and R ² each represent a methyl group, and R ³ and R ⁴ are bonded to each other to represent a cycloalkylidene group having 5 or 6 carbon atoms.

Hereinafter, the repeating unit represented by the general formula (1), the repeating unit represented by the chemical formula (2), and the repeating unit represented by the chemical formula (3) are referred to as a repeating unit (1) and a repeating unit (2), respectively. ), And the repeating unit (3). Further, the ratio n ₁ / n ₂ of the number n ₁ of the repeating unit (1) to the number n ₂ of the repeating unit (2) includes the repeating unit (1), the repeating unit (2), and the repeating unit (3). A polyallylate resin having a value of 1.0 or more may be referred to as a polyallylate resin (PA).

When the polyarylate resin (PA) is contained in the photosensitive layer, the abrasion resistance of the photoconductor can be improved. The reason is presumed as follows.

First, the polyarylate resin (PA) contains a repeating unit (2) and a repeating unit (3). Thereby, the wear resistance of the photoconductor can be improved.

Second, the polyarylate resin (PA) contains a repeating unit (1). Thereby, the solubility of the polyarylate resin (PA) in the solvent for forming the photosensitive layer can be improved. Further, when the ratio n ₁ / n ₂ of the number n ₁ of the repeating unit (1) to the number n ₂ of the repeating unit (2) is 1.0 or more, the polyarylate resin (PA) to the solvent for forming the photosensitive layer is formed. ) Can be further improved. By improving the solubility of the polyarylate resin (PA), the photosensitive layer can be suitably formed, and the abrasion resistance of the photoconductor can be improved.

Next, the general formula (1) will be described in detail. Examples of the alkyl group having 2 or 3 carbon atoms represented by R ⁴ in the general formula (1) include an ethyl group, an n-propyl group, and an isopropyl group. As the alkyl group having 2 or 3 carbon atoms, an ethyl group or an isopropyl group is preferable.

Examples of the cycloalkylidene group having 5 or 6 carbon atoms represented by the bonds of R ³ and R ⁴ in the general formula (1) include a cyclopentylidene group and a cyclohexylidene group. The cyclopentylidene group and the cyclohexylidene group are divalent groups represented by the following chemical formulas (5) and (6), respectively. As the cycloalkylidene group having 5 or 6 carbon atoms, a cyclohexylidene group is preferable.

Preferable examples of the repeating unit (1) are represented by chemical formulas (1-1), chemical formulas (1-2), chemical formulas (1-3), chemical formulas (1-4), and chemical formulas (1-5). Repeat units can be mentioned. Hereinafter, the repeating units represented by the chemical formula (1-1), the chemical formula (1-2), the chemical formula (1-3), the chemical formula (1-4), and the chemical formula (1-5) are each repeated units ( It may be described as 1-1), (1-2), (1-3), (1-4), and (1-5).

The polyarylate resin (PA) may contain only one repeating unit (1). Alternatively, the polyarylate resin (PA) may contain two or more repeating units (1).

The ratio n ₁ / n ₂ of the number n ₁ of the repeating units (1) contained in the polyarylate resin (PA) to the number n ₂ of the repeating units (2) contained in the polyarylate resin (PA) is 1.0. That is all. That is, the number n ₁ of the repeating unit (1) is equal to the number n ₂ of the repeating unit (2) or larger than the number n ₂ of the repeating unit (2). When the ratio n ₁ / n ₂ is 1.0 or more, the solubility of the polyarylate resin (PA) in the solvent for forming the photosensitive layer can be improved, and the wear resistance of the photoconductor can be improved. .. In order to improve the abrasion resistance of the photoconductor, the ratio n ₁ / n ₂ is preferably 10.0 or less, and more preferably 5.0 or less. In order to improve the solubility of the polyarylate resin (PA) in the solvent for forming the photosensitive layer and to improve the abrasion resistance of the photoconductor, the ratio n ₁ / n ₂ is 1.0, 2.0, It is also preferably within the range of two values selected from 3.0, 5.0, and 10.0. The ratio n ₁ / n ₂ may be, for example, 1.0 or more and less than 2.0, or 2.0 or more and 5.0 or less. The ratio n ₁ / n ₂ may be, for example, 1.0 or 3.0.

The ratio n ₁ / n ₂ can be adjusted by changing the amount of the compound (BP-1) and the amount of the compound (BP-2) added when producing the polyarylate resin (PA). .. The compound (BP-1) and the compound (BP-2) will be described later.

The ratio n ₁ / n ₂ is a peak characteristic of each repeating unit in the obtained ¹ H-NMR spectrum obtained by measuring the ¹ H-NMR spectrum of the polyarylate resin (PA) using a proton nuclear magnetic resonance spectrometer. It can be obtained by calculating the ratio of.

Specific examples of the polyarylate resin (PA) include the following polyarylate resins.
Described as a polyarylate resin (polyarylate resin (I)) containing the repeating units (1-1), (2), and (3) and having a ratio n ₁ / n ₂ of 2.0 or more and 5.0 or less. There is);
Describe as a polyarylate resin (polyarylate resin (II)) containing the repeating units (1-5), (2), and (3) and having a ratio n ₁ / n ₂ of 2.0 or more and 5.0 or less. There is);
Described as a polyarylate resin (polyarylate resin (III)) containing the repeating units (1-2), (2), and (3) and having a ratio n ₁ / n ₂ of 2.0 or more and 5.0 or less. There is);
Described as a polyarylate resin (polyarylate resin (IV)) containing the repeating units (1-3), (2), and (3) and having a ratio n ₁ / n ₂ of 2.0 or more and 5.0 or less. There is);
Described as a polyarylate resin (polyarylate resin (V)) containing the repeating units (1-4), (2), and (3) and having a ratio n ₁ / n ₂ of 2.0 or more and 5.0 or less. There is); and a polyarylate resin (polyarylate resin (VI)) containing the repeating units (1-1), (2), and (3) and having a ratio n ₁ / n ₂ of 1.0 or more and less than 2.0. ) May be described).

As a more specific example of the polyarylate resin (PA), the polyarylate resins represented by the chemical formulas (R-1) to (R-6) (hereinafter, each of which is a polyarylate resin (R-1) to (R)). -6) may be described). In the chemical formulas (R-1) to (R-6), the number attached to the lower right of each repeating unit is a percentage (%) of the number of each repeating unit with respect to the total number of repeating units contained in the polyarylate resin. ) Is shown. The total number of repeating units is the sum of the number of bisphenol-derived repeating units and the number of dicarboxylic acid-derived repeating units. Further, for convenience of description, two repeating units (3) are described in each of the chemical formulas (R-1) to (R-6). However, the percentage of the number of repeating units (3) to the total number of repeating units contained in each of the polyarylate resins (R-1) to (R-6) is 50.0% (two repeating units (3)). The sum of the numbers attached to the lower right of.

In the polyarylate resin (PA), the bisphenol-derived repeating unit and the dicarboxylic acid-derived repeating unit are adjacent to each other. The bisphenol-derived repeating unit is, for example, the repeating units (1) and (2). The repeating unit derived from dicarboxylic acid is, for example, the repeating unit (3). The polyarylate resin (PA) may be, for example, a random copolymer, an alternating copolymer, a periodic copolymer, or a block copolymer.

The polyarylate resin (PA) may contain only the repeating units (1), (2), and (3) as the repeating unit. The polyarylate resin (PA) may further contain a repeating unit other than these repeating units in addition to the repeating units (1), (2), and (3) as the repeating unit. The photosensitive layer may contain only one type of polyarylate resin (PA), or may contain two or more types of polyarylate resin (PA).

The viscosity average molecular weight of the polyarylate resin (PA) is preferably 10,000 or more, more preferably 20,000 or more, further preferably 30,000 or more, and 40,000 or more. Is particularly preferred. When the viscosity average molecular weight of the polyarylate resin (PA) is 10,000 or more, the abrasion resistance of the photoconductor can be improved. On the other hand, the viscosity average molecular weight of the polyarylate resin (PA) is preferably 80,000 or less, and more preferably 70,000 or less. When the viscosity average molecular weight of the polyarylate resin (PA) is 80,000 or less, the polyarylate resin (PA) is easily dissolved in the solvent for forming the photosensitive layer.

The method for producing the polyarylate resin (PA) is not particularly limited. Examples of the method for producing a polyarylate resin (PA) include a method of polycondensing a bisphenol for forming a bisphenol-derived repeating unit and a dicarboxylic acid for forming a dicarboxylic acid-derived repeating unit. For the polycondensation, a known synthesis method (for example, solution polymerization, melt polymerization or interfacial polymerization) can be adopted.

Examples of the bisphenol for forming the bisphenol repeating unit of the polyarylate resin (PA) include compounds represented by the general formula (BP-1) and the chemical formula (BP-2) (hereinafter, compound (BP-1) and (BP-2) may be described). The dicarboxylic acid for constituting the dicarboxylic acid repeating unit of the polyarylate resin (PA) is, for example, a compound represented by the chemical formula (DC-3) (hereinafter, may be referred to as a compound (DC-3)). Can be mentioned. R ¹ in the general formula ^{(BP-1), R 2} , R 3 and R ⁴ are each the same meaning as in formula ^{(1) R 1, R 2} , R 3 and R ⁴ in.

Preferable examples of the compound (BP-1) are the compounds represented by the chemical formulas (BP-1-1) to (BP-1-5) (hereinafter, each of the compounds (BP-1-1) to (BP-1). -1-5) may be described).

The bisphenol for forming the bisphenol-derived repeating unit may be derivatized with an aromatic diacetate and used. The dicarboxylic acid for forming the dicarboxylic acid-derived repeating unit may be derivatized and used. Examples of derivatives of dicarboxylic acids include dicarboxylic acid dichloride, dicarboxylic acid dimethyl ester, dicarboxylic acid diethyl ester, and dicarboxylic acid anhydride. The dicarboxylic acid dichloride is a compound in which the two "-C (= O) -OH" groups of the dicarboxylic acid are each replaced with a "-C (= O) -Cl" group.

In the polycondensation of bisphenol and dicarboxylic acid, one or both of the base and the catalyst may be added. Examples of bases include sodium hydroxide. Examples of catalysts include benzyltributylammonium chloride, ammonium chloride, ammonium bromide, quaternary ammonium salts, triethylamine, and trimethylamine.

The photosensitive layer may contain only polyarylate resin (PA) as the binder resin. Further, the photosensitive layer may further contain a binder resin other than the polyarylate resin (PA) (hereinafter, may be referred to as other binder resin) as the binder resin.

Examples of other binder resins include thermoplastic resins (more specifically, polycarbonate resins, styrene resins, styrene-butadiene copolymers, styrene-acrylonitrile copolymers, styrene-maleic acid copolymers, and 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, polyester resin, alkyd Resins, polyamide resins, polyurethane resins, polysulfone resins, diallyl phthalate resins, ketone resins, polyvinyl butyral resins, polyvinyl acetal resins, and polyether resins), thermosetting resins (more specifically, silicone resins, epoxy resins, phenols) Resins, urea resins, melamine resins, and other crosslinkable thermosetting resins), and photocurable resins (more specifically, epoxy-acrylic acid-based resins and urethane-acrylic acid-based copolymers) Can be mentioned.

(Azo compound)
The azo compound is represented by the general formula (10). Hereinafter, the azo compound represented by the general formula (10) may be referred to as an azo compound (10).

In the general formula (10), R ¹¹ and R ¹² each independently represent an alkyl group having 1 or more and 3 or less carbon atoms. Ar ¹ and Ar ² each independently represent an arylene group having 6 to 14 carbon atoms which may be substituted with at least one substituent. The substituent contained in the arylene group having 6 or more and 14 or less carbon atoms is selected from the group consisting of an alkyl group having 1 or more and 3 or less carbon atoms and an alkoxy group having 1 or more and 3 or less carbon atoms. Q represents a monovalent group represented by the general formula (Q1) or (Q2).

In the general formula (Q1), Ar ³ and Ar ⁴ each independently represent an aryl group having 6 to 14 carbon atoms which may be substituted with an alkyl group having 1 or more and 3 or less carbon atoms. In the general formula (Q2), Z represents a heterocycle having at least 6 members or more and 18 members or less having a nitrogen atom as a ring-constituting atom.

When the photosensitive layer contains the azo compound (10), it is possible to suppress the occurrence of image defects due to light exposure and image defects due to contact with a member included in the image forming apparatus. The reason is presumed as follows.

First, image defects caused by light exposure will be described. During maintenance of the image forming apparatus, the photoconductor provided in the image forming apparatus may be exposed to light (for example, fluorescent lamp light or external light). When an image is formed using an image forming apparatus after light exposure, the post-exposure potential of the peripheral surface region of the photoconductor exposed to light may be lower than the desired post-exposure potential. Hereinafter, the region of the peripheral surface of the photoconductor exposed to light will be referred to as a “light-exposed region”. Further, the region of the peripheral surface of the photoconductor that has not been exposed to light is referred to as a “non-light exposed region”. In the formed image, the image density of the image region corresponding to the light-exposed region where the post-exposure potential is lower than the desired post-exposure potential is higher than the image density of the image region corresponding to the non-light-exposed region. Such a phenomenon is called image defect due to light exposure. Here, the azo compound (10) absorbs the light exposed to the photoconductor. Therefore, the photoconductor provided with the photosensitive layer containing the azo compound (10) can suppress the post-exposure potential of the light-exposed region from dropping below a desired value, and causes image defects due to light exposure. Can be suppressed.

Next, an image defect caused by contact with a member included in the image forming apparatus will be described. When the photoconductor is placed in a high temperature and high humidity environment in a state where the member (for example, a charging roller) included in the image forming apparatus is in contact with the peripheral surface of the photoconductor, the material of the member (for example, the charging roller) is formed. The conductive material) may soak into the photosensitive layer of the photoconductor, and the photosensitive layer may be deteriorated. In addition, the photosensitive layer may be dented due to contact with the member, and the thickness of a part of the photosensitive layer may be reduced. Hereinafter, the region of the peripheral surface of the photoconductor in contact with the member will be referred to as a “member contact region”. Further, the region of the peripheral surface of the photoconductor that is not in contact with the member is described as "non-member contact region". Due to such alteration and reduction in thickness of the photosensitive layer, the image density of the image region corresponding to the member contact region may be higher than the image density of the image region corresponding to the non-member contact region in the formed image. .. Such a phenomenon is called an image defect caused by contact with a member included in the image forming apparatus. Here, the photoconductor provided with the photosensitive layer containing the azo compound (10) can suppress deterioration of the photosensitive layer and reduction in thickness, and can suppress the occurrence of image defects due to light exposure. This advantage becomes remarkable when the photosensitive layer contains both the azo compound (10) and the polyarylate resin (PA).

Hereinafter, the general formula (10) will be further described. As the alkyl group represented by R ¹¹ and R ¹² having 1 or more and 3 or less carbon atoms, a methyl group or an ethyl group is preferable.

As the arylene group represented by Ar ¹ and Ar ² having 6 or more and 14 or less carbon atoms, an arylene group having 6 or more and 10 or less carbon atoms is preferable, a phenylene group is more preferable, and a p-phenylene group is further preferable. The arylene represented by Ar ¹ and Ar ² having 6 to 14 carbon atoms may be substituted with at least one substituent. Such a substituent is preferably one or two substituents selected from the group consisting of an alkyl group having 1 or more and 3 or less carbon atoms and an alkoxy group having 1 or more and 3 or less carbon atoms. It is more preferable that such a substituent is one or two substituents selected from the group consisting of a methyl group, an ethyl group, and a methoxy group. Examples of the arylene group having 6 to 14 carbon atoms which may be substituted with at least one substituent represented by Ar ¹ and Ar ² include a phenylene group, a methylphenylene group, an ethylphenylene group, a dimethylphenylene group, or a methoxyphenylene group. Is preferable. Examples of the arylene group having 6 to 14 carbon atoms which may be substituted with at least one substituent represented by Ar ¹ and Ar ² include p-phenylene group, 2-methyl-1,4-phenylene group and 3-methyl. -1,4-phenylene group, 2-ethyl-1,4-phenylene group, 2,5-dimethyl-1,4-phenylene group, 2,6-dimethyl-1,4-phenylene group, or 3-methoxy- A 1,4-phenylene group is more preferable.

* In the general formulas (Q1) and (Q2) represents a bond. Specifically, * represents a bond to the nitrogen atom to which Q is bonded in the general formula (10).

As the aryl group having 6 to 14 carbon atoms represented by Ar ³ and Ar ⁴ in the general formula (Q1), a phenyl group or a naphthyl group is preferable. As the naphthyl group, a 1-naphthyl group is preferable. The aryl group represented by Ar ³ and Ar ⁴ having 6 or more and 14 or less carbon atoms may be substituted with an alkyl group having 1 or more and 3 or less carbon atoms.

As described above, Z in the general formula (Q2) represents a heterocycle having at least 6 members or more and 18 members or less having a nitrogen atom as a ring-constituting atom. N in the general formula (Q2) represents a nitrogen atom which is a ring-constituting atom. The nitrogen atom, which is a ring-constituting atom represented by the general formula (Q2), has a bond. Specifically, the nitrogen atom, which is a ring-constituting atom represented by the general formula (Q2), is bonded to the nitrogen atom to which Q in the general formula (10) is bonded.

As the heterocycle having 6 or more and 18 or less members represented by Z in the general formula (Q2), a heterocycle having 13 or more and 15 or less members is preferable. The monovalent group represented by the general formula (Q2) is preferably a monovalent group represented by the following general formula (Q2-1) or chemical formula (Q2-2).

In the general formula (Q2-1), W represents a carbon atom or an oxygen atom. p represents an integer of 0 or more and 2 or less. When p represents 2, the two Ws may be the same or different. In the general formula (Q2-1) and the chemical formula (Q2-2), * represents a bond. In the general formula (Q2-1), it is preferable that W represents an oxygen atom and p represents 1. It is also preferable that p represents 0 in the general formula (Q2-1).

The azo compound (10) preferably contains at least one compound (for example, one compound) among the compounds represented by the chemical formulas (ADD-1) to (ADD-8). That is, the photosensitive layer preferably contains at least one compound (for example, one compound) among the compounds represented by the chemical formulas (ADD-1) to (ADD-8) as the azo compound (10). .. Hereinafter, the compounds represented by the chemical formulas (ADD-1) to (ADD-8) may be described as azo compounds (ADD-1) to (ADD-8), respectively.

The content of the azo compound (10) is preferably 2 parts by mass or more and 11 parts by mass or less with respect to 100 parts by mass of the binder resin. When the content of the azo compound (10) is 2 parts by mass or more, the occurrence of image defects due to light exposure can be further suppressed. On the other hand, when the content of the azo compound (10) is 11 parts by mass or less, the abrasion resistance of the photoconductor can be further improved.

In order to particularly improve the abrasion resistance of the photoconductor, the content of the azo compound (10) is more preferably 2 parts by mass or more and 7 parts by mass or less with respect to 100 parts by mass of the binder resin. It is more preferably parts by mass or more and 5 parts by mass or less.

In order to particularly suppress the occurrence of image defects due to contact with members included in the image forming apparatus, the content of the azo compound (10) is 7 parts by mass or more and 11 parts by mass with respect to 100 parts by mass of the binder resin. More preferably, it is less than or equal to a portion. When a compound other than the azo compound (10) (for example, other compounds (E-1) to (E-11) described later in the examples) is contained in an amount of 7 parts by mass or more with respect to 100 parts by mass of the binder resin. Causes image defects due to contact between the member included in the image forming apparatus and the photoconductor. However, since the azo compound (10) has a specific chemical structure, even when it is contained in an amount of 7 parts by mass or more with respect to 100 parts by mass of the binder resin, the member and the photoconductor provided in the image forming apparatus The occurrence of image defects due to contact can be suitably suppressed.

(Hole transport agent)
Examples of the hole transporting agent include triphenylamine derivatives and diamine derivatives (for example, N, N, N', N'-tetraphenylbenzidine derivatives, N, N, N', N'-tetraphenylphenylenediamine derivatives, etc. N, N, N', N'-tetraphenylnaphthylene diamine derivative, N, N, N', N'-tetraphenylphenanthrylene diamine derivative, and di (aminophenylethenyl) benzene derivative), oxadiazole System compounds (for example, 2,5-di (4-methylaminophenyl) -1,3,4-oxadiazole), styryl compounds (for example, 9- (4-diethylaminostyryl) anthracene), carbazole compounds (for example) For example, polyvinylcarbazole), organic polysilane compounds, pyrazoline compounds (eg, 1-phenyl-3- (p-dimethylaminophenyl) pyrazoline), hydrazone compounds, indol compounds, oxazole compounds, isooxazole compounds, thiazole. Examples thereof include system compounds, thiadiazol system compounds, imidazole system compounds, pyrazole system compounds, and triazole system compounds.

In order to improve the abrasion resistance of the photoconductor and suppress the occurrence of image defects due to light exposure and image defects due to contact with a member provided in the image forming apparatus, the hole transport agent is of a general formula ( It is preferable to contain at least one compound (for example, one compound) among the compounds represented by 20) to (22). That is, the photosensitive layer preferably contains at least one compound (for example, one compound) among the compounds represented by the general formulas (20) to (22) as a hole transporting agent. Hereinafter, the compounds represented by the general formulas (20) to (22) may be described as hole transporting agents (20) to (22), respectively.

In the general formula (20), R ²¹ and R ²² independently represent an alkyl group having 1 or more and 8 or less carbon atoms, a phenyl group, or an alkoxy group having 1 or more and 8 or less carbon atoms. R ²³ and R ²⁴ are each independently substituted with an alkyl group having 1 or more and 8 or less carbon atoms, a phenyl group, a hydrogen atom, an alkyl group having 1 or more and 8 or less carbon atoms, or 1 or more carbon atoms. Represents an alkoxy group of 8 or less. R ²⁵ , R ²⁶ , R ²⁷ , R ²⁸ , and R ²⁹ each independently contain a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, a phenyl group, or an alkoxy group having 1 to 8 carbon atoms. Represent. Adjacent two of R ²⁵ , R ²⁶ , R ²⁷ , R ²⁸ , and R ²⁹ may be combined to represent a ring. a1 and a2 each independently represent an integer of 0 or more and 5 or less.

In the general formula (20), when a1 represents an integer of 2 or more and 5 or less, a plurality of R ^21s may be the same as each other or may be different from each other. When a2 represents an integer of 2 or more and 5 or less, a plurality of R ^22s may be the same as each other or may be different from each other. If two adjacent two of R ²⁵ , R ²⁶ , R ²⁷ , R ²⁸ , and R ²⁹ combine with each other to form a ring, then this ring and R ²⁵ , R ²⁶ , R ²⁷ , R ²⁸ , and The phenyl group to which R ²⁹ is bonded is condensed to form a bicyclic fused ring group. In this case, the condensation site between the ring and the phenyl group may contain a double bond.

In the general formula (20), R ²¹ and R ²² each independently preferably represent an alkyl group having 1 or more and 8 or less carbon atoms, and more preferably represent an alkyl group having 1 or more and 3 or less carbon atoms. , It is more preferable to represent a methyl group. It is preferable that R ²³ and R ²⁴ each independently represent a phenyl group or a hydrogen atom which may be substituted with an alkyl group having 1 or more and 8 or less carbon atoms. As the phenyl group represented by R ²³ and R ²⁴ which may be substituted with an alkyl group having 1 or more and 8 or less carbon atoms, a phenyl group which may be substituted with an alkyl group having 1 or more and 3 or less carbon atoms is preferable, and carbon. A phenyl group substituted with an alkyl group having 1 or more and 3 or less atoms is more preferable, a methylphenyl group is further preferable, and a 4-methylphenyl group is particularly preferable. R ²⁵ , R ²⁶ , R ²⁷ , R ²⁸ , and R ²⁹ can each independently represent a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, or an alkoxy group having 1 to 8 carbon atoms. preferable. The alkyl group represented by R ²⁵ , R ²⁶ , R ²⁷ , R ²⁸ , and R ²⁹ having 1 or more and 8 or less carbon atoms is preferably an alkyl group having 1 or more and 6 or less carbon atoms, and is preferably a methyl group, an ethyl group, or an ethyl group. The n-butyl group is more preferable. As the alkoxy group represented by R ²⁵ , R ²⁶ , R ²⁷ , R ²⁸ , and R ²⁹ having 1 or more and 8 or less carbon atoms, an alkoxy group having 1 or more and 3 or less carbon atoms is preferable, and a methoxy group is more preferable. When two adjacent two of R ²⁵ , R ²⁶ , R ²⁷ , R ²⁸ , and R ²⁹ are bonded to form a ring, cycloalkane having 5 or more and 7 or less carbon atoms is preferable as such a ring. Cyclohexane is more preferred. It is preferable that a1 and a2 independently represent 0 or 1, respectively.

In the general formula (21), R ^{31 to} R ³⁶ independently represent an alkyl group or a phenyl group having 1 to 8 carbon atoms. R ³⁷ and R ³⁸ each independently represent a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, or a phenyl group. b1, b2, b3, and b4 each independently represent an integer of 0 or more and 5 or less. b5 and b6 each independently represent an integer of 0 or more and 4 or less. d and e independently represent 0 or 1, respectively.

In the general formula (21), when b1 represents an integer of 2 or more and 5 or less, a plurality of R ^31s may be the same as each other or may be different from each other. When b2 represents an integer of 2 or more and 5 or less, the plurality of R ^32s may be the same as or different from each other. When b3 represents an integer of 2 or more and 5 or less, the plurality of R ^33s may be the same as or different from each other. When b4 represents an integer of 2 or more and 5 or less, the plurality of R ^34s may be the same as or different from each other. When b5 represents an integer of 2 or more and 4 or less, the plurality of R ^35s may be the same as or different from each other. When b6 represents an integer of 2 or more and 4 or less, the plurality of R ^36s may be the same as or different from each other.

In the general formula (21), R ^{31 to} R ³⁶ each independently preferably represent an alkyl group having 1 or more and 8 or less carbon atoms, and more preferably represent an alkyl group having 1 or more and 3 or less carbon atoms. , Methyl group or ethyl group is more preferable. It is preferable that R ³⁷ and R ³⁸ each independently represent a hydrogen atom or a phenyl group. It is preferable that b1, b2, b3, and b4 each independently represent an integer of 0 or more and 2 or less. It is preferable that b5 and b6 each represent 0.

In the general formula (22), R ^{41 to} R ⁴⁶ independently represent an alkyl group having 1 or more and 8 or less carbon atoms, a phenyl group, or an alkoxy group having 1 or more and 8 or less carbon atoms. f1, f2, f4, and f5 each independently represent an integer of 0 or more and 5 or less. Each of f3 and f6 independently represents an integer of 0 or more and 4 or less.

In the general formula (22), when f1 represents an integer of 2 or more and 5 or less, a plurality of R ^41s may be the same as each other or may be different from each other. When f2 represents an integer of 2 or more and 5 or less, a plurality of R ^42s may be the same as each other or may be different from each other. When f4 represents an integer of 2 or more and 5 or less, the plurality of R ^44s may be the same as or different from each other. When f5 represents an integer of 2 or more and 5 or less, a plurality of R ^45s may be the same as each other or may be different from each other. When f3 represents an integer of 2 or more and 4 or less, a plurality of R ^43s may be the same as each other or may be different from each other. When f6 represents an integer of 2 or more and 4 or less, the plurality of R ^46s may be the same as or different from each other.

In the general formula (22), R ^{41 to} R ⁴⁶ each independently preferably represent an alkyl group having 1 or more and 8 or less carbon atoms, and more preferably represent an alkyl group having 1 or more and 3 or less carbon atoms. , Methyl group or ethyl group is more preferable. It is preferable that f1, f2, f4, and f5 each independently represent an integer of 0 or more and 2 or less. It is preferable that f3 and f6 each represent 0. R ^44, R ^45, and diphenylamino phenylethenyl group having R ⁴⁶ is, R ^41, R ^42, and against diphenylamino phenylethenyl group having R ^43, bonded to the ortho or para position of the phenyl group It is preferable to do so.

The hole transporting agent is preferably at least one compound (for example, one compound) among the compounds represented by the chemical formulas (HTM-1) to (HTM-9). Hereinafter, the compounds represented by the chemical formulas (HTM-1) to (HTM-9) may be described as hole transport agents (HTM-1) to (HTM-9), respectively.

The hole transporting agents (HTM-1) to (HTM-4) are each suitable examples of the hole transporting agent (20). The hole transport agents (HTM-5) to (HTM-7) are good examples of the hole transport agents (21), respectively. The hole transport agents (HTM-8) to (HTM-9) are good examples of the hole transport agents (22), respectively.

The photosensitive layer may contain only at least one compound of the hole transporting agents (20) to (22) as the hole transporting agent. Further, in the photosensitive layer, as the hole transporting agent, in addition to at least one compound of the hole transporting agents (20) to (22), other hole transporting agents (hereinafter, other hole transporting agents). May be further contained.

When the photoconductor is a laminated photoconductor, the content of the hole transporting agent is preferably 10 parts by mass or more and 200 parts by mass or less, and 20 parts by mass or more and 100 parts by mass or less, based on 100 parts by mass of the binder resin. It is more preferably 40 parts by mass or more and 50 parts by mass or less. When the photoconductor is a single-layer photoconductor, the content of the hole transporting agent is preferably 50 parts by mass or more and 200 parts by mass or less with respect to 100 parts by mass of the binder resin.

(Charge generator)
Examples of the charge generator include phthalocyanine pigments, perylene pigments, bisazo pigments, trisazo pigments, dithioketopyrrolopyrrole pigments, metal-free naphthalocyanine pigments, metal naphthalocyanine pigments, squaline pigments, indigo pigments, azulenium pigments, and cyanine. Pigments, powders of inorganic photoconductive materials (eg, selenium, selenium-tellu, selenium-arsenic, cadmium sulfide, and amorphous silicon), pyririum pigments, anthanthrone pigments, triphenylmethane pigments, slen pigments, toluidine pigments , Pyrazoline pigments, and quinacridone pigments. The photosensitive layer may contain only one type of charge generating agent, or may contain two or more types.

The phthalocyanine pigment is a pigment having a phthalocyanine structure. Examples of the phthalocyanine pigment include metal-free phthalocyanine and metal phthalocyanine. Examples of the metallic phthalocyanine include titanyl phthalocyanine, hydroxygallium phthalocyanine, and chlorogallium phthalocyanine. Metal-free phthalocyanines are represented by the chemical formula (CGM-1). Titanyl phthalocyanine is represented by the chemical formula (CGM-2).

The phthalocyanine pigment may be crystalline or non-crystalline. Examples of the crystal of the metal-free phthalocyanine include an X-type crystal of the metal-free phthalocyanine (hereinafter, may be referred to as an X-type metal-free phthalocyanine). Examples of the crystals of titanyl phthalocyanine include α-type, β-type, and Y-type crystals of titanyl phthalocyanine (hereinafter, each may be referred to as α-type, β-type, and Y-type titanyl phthalocyanine).

For example, it is preferable to use a photoconductor having sensitivity in a wavelength region of 700 nm or more for a digital optical image forming apparatus (for example, a laser beam printer or a facsimile using a light source such as a semiconductor laser). Since it has a high quantum yield in the wavelength region of 700 nm or more, the phthalocyanine pigment is preferable, metal-free phthalocyanine or titanyl phthalocyanine is more preferable, titanyl phthalocyanine is further preferable, and Y-type titanyl phthalocyanine is particularly preferable. ..

The Y-type titanyl phthalocyanine has a main peak at 27.2 ° of the Bragg angle (2θ ± 0.2 °) in the CuKα characteristic X-ray diffraction spectrum, for example. The main peak in the CuKα characteristic X-ray diffraction spectrum is the peak having the first or second highest intensity in the range where the Bragg angle (2θ ± 0.2 °) is 3 ° or more and 40 ° or less. Y-type titanyl phthalocyanine does not have a peak at 26.2 ° C. in the CuKα characteristic X-ray diffraction spectrum.

The CuKα characteristic X-ray diffraction spectrum can be measured by, for example, the following method. First, a sample (titanyl phthalocyanine) is filled in a sample holder of an X-ray diffractometer (for example, "RINT (registered trademark) 1100" manufactured by Rigaku Co., Ltd.), and an X-ray tube Cu, tube voltage 40 kV, tube current 30 mA, The X-ray diffraction spectrum is measured under the condition that the wavelength of CuKα characteristic X-ray is 1.542 Å. The measurement range (2θ) is, for example, 3 ° or more and 40 ° or less (start angle 3 °, stop angle 40 °), and the scanning speed is, for example, 10 ° / min. The main peak is determined from the obtained X-ray diffraction spectrum, and the Bragg angle of the main peak is read.

When the photoconductor is a laminated photoconductor, the content of the charge generator is preferably 10 parts by mass or more and 300 parts by mass or less, and 100 parts by mass or more and 200 parts by mass or less with respect to 100 parts by mass of the base resin. Is more preferable. When the photoconductor is a single-layer photoconductor, the content of the charge generator is preferably 0.1 part by mass or more and 50 parts by mass or less, and 0.5 part by mass with respect to 100 parts by mass of the binder resin. It is more preferably 30 parts by mass or less.

(Base resin)
The example of the base resin contained in the charge generation layer is the same as the example of the other binder resin contained in the charge transport layer.

(Additive)
Additives include, for example, UV absorbers, antioxidants, radical scavengers, singlet quenchers, softeners, surface modifiers, bulking agents, thickeners, dispersion stabilizers, waxes, donors, surfactants. Examples include agents, plasticizers, sensitizers, electron acceptor compounds, and leveling agents.

(Combination of materials)
In order to improve the abrasion resistance of the photoconductor and suppress the occurrence of image defects due to light exposure and image defects due to contact with members of the image forming apparatus, a combination of a polyarylate resin and an azo compound is used. , Combination No. shown in Table 1. It is preferably each of F1 to F30. For the same reason, the combination of the polyarylate resin and the azo compound is the combination No. 1 shown in Table 1. It is each of F1 to F30, and it is more preferable that the charge generator is Y-type titanylphthalocyanine.

In order to improve the abrasion resistance of the photoconductor and suppress the occurrence of image defects due to light exposure and image defects due to contact with members of the image forming apparatus, polyarylate resins, hole transport agents, etc. And the combinations of azo compounds are the combination Nos. shown in Table 2. It is preferably each of G1 to G46. For the same reason, the combinations of the polyarylate resin, the hole transporting agent, and the azo compound are the combinations No. 2 shown in Table 2. It is each of G1 to G46, and it is more preferable that the charge generator is Y-type titanylphthalocyanine.

The meanings of the terms in Tables 1 and 2 above are as follows. "No." indicates "combination No.". "Resin" indicates "polyarylate resin". "Azo" indicates an "azo compound". "HTM" stands for "hole transporter".

(Conductive substrate)
The conductive substrate is not particularly limited as long as it can be used as the conductive substrate of the photoconductor. The conductive substrate may be made of a material having a conductive surface at least. An example of a conductive substrate is a conductive substrate made of a conductive material. Another example of a conductive substrate is a conductive substrate coated with a conductive material. Materials having conductivity include, for example, 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 conductive materials, aluminum and aluminum alloys are preferable because the transfer of electric charges from the photosensitive layer to the conductive substrate is good.

The shape of the conductive substrate is appropriately selected according to the structure of the image forming apparatus. Examples of the shape of the conductive substrate include a sheet shape and a drum shape. The thickness of the conductive substrate is appropriately selected according to the shape of the conductive substrate.

(Middle layer)
The intermediate layer (undercoat layer) contains, for example, inorganic particles and a resin (resin for the intermediate layer) used for the intermediate layer. By the presence of the intermediate layer, it is possible to smooth the flow of the current generated when the photoconductor is exposed and suppress the increase in resistance while maintaining the insulating state to the extent that the occurrence of leakage can be suppressed.

Inorganic particles include, for example, metal (eg, aluminum, iron, and copper) particles, metal oxide (eg, titanium oxide, alumina, zirconium oxide, tin oxide, and zinc oxide) particles, and non-metal oxides. (For example, silica) particles can be mentioned. One type of these inorganic particles may be used alone, or two or more types may be used in combination.

The example of the resin for the intermediate layer is the same as the example of other binder resins contained in the photosensitive layer. In order to form the intermediate layer and the photosensitive layer well, it is preferable that the resin for the intermediate layer is different from the binder resin contained in the photosensitive layer. The intermediate layer may contain additives. The example of the additive contained in the intermediate layer is the same as the example of the additive contained in the photosensitive layer.

(Manufacturing method of photoconductor)
As a method for producing a photoconductor, an example of a method for producing a laminated photoconductor and an example of a method for producing a single-layer photoconductor will be described.

The method for producing a laminated photoconductor includes a charge generation layer forming step and a charge transport layer forming step. In the charge generation layer forming step, first, a coating liquid for forming the charge generation layer (hereinafter, may be referred to as a charge generation layer coating liquid) is prepared. The coating liquid for the charge generation layer is applied onto the conductive substrate. Next, at least a part of the solvent contained in the coated liquid for the charge generation layer is removed to form the charge generation layer. The coating liquid for the charge generating layer contains, for example, a charge generating agent, a base resin, and a solvent. Such a coating liquid for a charge generating layer is prepared by dissolving or dispersing a charge generating agent and a base resin in a solvent. The coating liquid for the charge generation layer may further contain additives, if necessary.

In the charge transport layer forming step, first, a coating liquid for forming the charge transport layer (hereinafter, may be referred to as a charge transport layer coating liquid) is prepared. The coating liquid for the charge transport layer is applied onto the charge generation layer. Next, at least a part of the solvent contained in the coated liquid for the charge transport layer is removed to form the charge transport layer. The coating liquid for the charge transport layer contains a hole transport agent, an azo compound, a binder resin, and a solvent. The coating liquid for the charge transport layer can be prepared by dissolving or dispersing the hole transport agent, the azo compound, and the binder resin in a solvent. The coating liquid for the charge transport layer may further contain additives, if necessary.

The method for producing a single-layer photosensitive layer includes a single-layer photosensitive layer forming step. In the single-layer type photosensitive layer forming step, a coating liquid for forming the single-layer type photosensitive layer (hereinafter, may be referred to as a coating liquid for a single-layer type photosensitive layer) is prepared. A coating liquid for a single-layer photosensitive layer is applied onto a conductive substrate. Next, at least a part of the solvent contained in the coated liquid for the photosensitive layer is removed to form a single-layer type photosensitive layer. The coating liquid for a single-layer photosensitive layer contains, for example, a charge generator, a hole transporting agent, an azo compound, a binder resin, and a solvent. The coating liquid for a single-layer photosensitive layer is prepared by dissolving or dispersing a charge generator, a hole transporting agent, an azo compound, and a binder resin in a solvent. The coating liquid for a single-layer photosensitive layer may further contain an electron transporting agent. The coating liquid for a single-layer photosensitive layer may further contain an additive, if necessary.

The solvent contained in the coating liquid for a single-layer photosensitive layer, the coating liquid for a charge generating layer, and the coating liquid for a charge transport layer (hereinafter, these may be collectively referred to as a coating liquid) is contained in the coating liquid. It is not particularly limited as long as each component contained can be dissolved or dispersed. Solvents include, for example, alcohols (more specifically methanol, ethanol, isopropanol, butanol, etc.), aliphatic hydrocarbons (more specifically n-hexane, octane, cyclohexane, etc.), aromatic hydrocarbons, etc. Hydrogen (more specifically, benzene, toluene, xylene, etc.), halogenated hydrocarbons (more specifically, dichloromethane, dichloroethane, carbon tetrachloride, and chlorobenzene, etc.), ethers (more specifically, dimethyl ether, etc.) , Diethyl ether, tetrahydrofuran, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, etc.), ketones (more specifically, acetone, methyl ethyl ketone, and cyclohexanone, etc.), esters (more specifically, ethyl acetate, methyl acetate, etc.), Included are dimethyl formaldehyde, dimethylformamide, and dimethylsulfoxide. One of these solvents may be used alone, or two or more of these solvents may be used in combination.

The solvent contained in the coating liquid for the charge transport layer is preferably different from the solvent contained in the coating liquid for the charge generating layer. This is because when the charge transport layer coating liquid is applied onto the charge generation layer, it is preferable that the charge generation layer is not dissolved in the solvent of the charge transport layer coating liquid.

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

The method of applying the coating liquid is not particularly limited as long as the coating liquid can be applied uniformly. Examples of the coating method include a dip coating method, a spray coating method, a spin coating method, and a bar coating method.

Examples of the method for removing at least a part of the solvent contained in the coating liquid include heating, depressurization, or combined use of heating and depressurization. More specifically, a method of heat treatment (hot air drying) using a high temperature dryer or a vacuum dryer can be mentioned. The temperature of the heat treatment is, for example, 40 ° C. or higher and 150 ° C. or lower. The heat treatment time is, for example, 3 minutes or more and 120 minutes or less.

The method for producing the photoconductor may further include a step of forming an intermediate layer, if necessary. A known method can be appropriately selected for the step of forming the intermediate layer.

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

<Preparation of hole transport agent>
As the hole transporting agent, the hole transporting agents (HTM-1) to (HTM-9) described in the embodiment were prepared.

<Preparation of azo compound>
As the azo compound, the azo compounds (ADD-1) to (ADD-8) described in the embodiment were prepared.

<Preparation of other compounds used in the comparative example>
As other compounds used in the comparative example, the compounds represented by the following chemical formulas (E-1) to (E-11) (hereinafter, each of them is described as other compounds (E-1) to (E-11). I have to prepare). Other compounds (E-1) to (E-11) are not included in the general formula (10). Each of the other compounds (E-1) to (E-11) was used in place of the azo compound (10) in Comparative Examples.

<Preparation of polyarylate resins (R-1) to (R-6)>
Each of the polyarylate resins (R-1) to (R-6) described in the embodiment was synthesized by the following method.

(Synthesis of polyarylate resin (R-1))
As the reaction vessel, a three-necked flask equipped with a thermometer, a three-way cock, and a dropping funnel was used. In a reaction vessel, compound (BP-1-1) (30.9 mmol), compound (BP-2) (10.3 mmol), p-tert-butylphenol (0.413 mmol), and sodium hydroxide (98 mmol) and benzyltributylammonium chloride (0.384 mmol) were added. The air in the reaction vessel was replaced with argon gas. Water (300 mL) was added to the contents of the reaction vessel. The contents of the reaction vessel were stirred at 50 ° C. for 1 hour. The contents of the reaction vessel were cooled until the temperature of the contents of the reaction vessel reached 10 ° C. to obtain an alkaline aqueous solution A.

Next, the dicarboxylic acid dichloride (32.4 mmol) of compound (DC-3) was dissolved in chloroform (150 mL). As a result, chloroform solution B was obtained.

Chloroform solution B was slowly added dropwise to the alkaline aqueous solution A over 110 minutes using a dropping funnel. While adjusting the temperature (liquid temperature) of the contents of the reaction vessel to 15 ± 5 ° C., the contents of the reaction vessel were stirred for 4 hours to proceed with the polymerization reaction. The upper layer (aqueous layer) of the contents of the reaction vessel was removed using a decant to obtain an organic layer. Then, ion-exchanged water (400 mL) was added to the Erlenmeyer flask. The obtained organic layer was further added to the Erlenmeyer flask. Chloroform (400 mL) and acetic acid (2 mL) were further added to the Erlenmeyer flask. The contents of the Erlenmeyer flask were stirred at room temperature (25 ° C.) for 30 minutes. The upper layer (aqueous layer) of the contents of the Erlenmeyer flask was removed using a decant to obtain an organic layer. The obtained organic layer was washed with ion-exchanged water (1 L) using a separating funnel. Washing with ion-exchanged water was repeated 5 times to obtain an organic layer washed with water. Next, the organic layer washed with water was filtered to obtain a filtrate. The obtained filtrate was slowly added dropwise to methanol (1 L) to obtain a precipitate. The precipitate was removed by filtration. The removed precipitate was vacuum dried at a temperature of 70 ° C. for 12 hours. As a result, a polyarylate resin (R-1) was obtained.

(Synthesis of polyarylate resin (R-2))
By the same method as the synthesis of polyarylate resin (R-1), except that the compound (BP-1-1) (30.9 mmol) was changed to the compound (BP-1-5) (30.9 mmol). A polyarylate resin (R-2) was obtained.

(Synthesis of polyarylate resin (R-3))
By the same method as the synthesis of polyarylate resin (R-1), except that the compound (BP-1-1) (30.9 mmol) was changed to the compound (BP-1-2) (30.9 mmol). A polyarylate resin (R-3) was obtained.

(Synthesis of polyarylate resin (R-4))
By the same method as the synthesis of polyarylate resin (R-1), except that the compound (BP-1-1) (30.9 mmol) was changed to the compound (BP-1--3) (30.9 mmol). A polyarylate resin (R-4) was obtained.

(Synthesis of polyarylate resin (R-5))
By the same method as the synthesis of polyarylate resin (R-1), except that the compound (BP-1-1) (30.9 mmol) was changed to the compound (BP-1--4) (30.9 mmol). A polyarylate resin (R-5) was obtained.

(Synthesis of polyarylate resin (R-6))
Compound (BP-1-1) (30.9 mmol) and compound (BP-2) (10.3 mmol), compound (BP-1-1) (20.6 mmol) and compound (BP-2). A polyallylate resin (R-6) was obtained by the same method as the synthesis of the polyarylate resin (R-1) except that the content was changed to (20.6 mmol).

The viscosity average molecular weights of the obtained polyarylate resins (R-1), (R-2), (R-3), (R-4), (R-5), and (R-6) are, respectively. They were 50500, 51,000, 45,000, 47,300, 45,500, and 48,700.

The ¹ H-NMR spectra of the obtained polyarylate resins (R-1) to (R-6) were measured using a proton nuclear magnetic resonance spectrometer (manufactured by JASCO Corporation, 300 MHz). CDCl ₃ was used as the solvent. Tetramethylsilane (TMS) was used as the internal standard sample. As a typical example of the polyarylate resins (R-1) to (R-6), the chemical shift values of the polyarylate resin (R-6) are shown below. From the chemical shift value, it was confirmed that the polyarylate resin (R-6) was obtained. It was confirmed that the polyarylate resins (R-1) to (R-5) were obtained by the same method for the polyarylate resins (R-1) to (R-5).

Polyarylate resin (R-6): ^{1 1} H-NMR (300 MHz, CDCl ₃ ) δ = 8.21-8.26 (m, 8H), 7.25-7.29 (m, 4H), 7.07 -7.23 (m, 20H), 2.16 (q, 2H), 1.65 (s, 3H), 0.78 (t, 3H).

<Preparation of polyarylate resin used in comparative example>
Further, as the polyarylate resin used in the comparative example, each of the polyarylate resins (RA) to (RD) was prepared. Each of the polyarylate resins (RA) to (RC) is represented by the following chemical formulas (RA) to (RC). The number attached to the lower right of each repeating unit indicates the percentage (%) of the number of each repeating unit with respect to the total number of repeating units contained in the polyarylate resin.

The polyarylate resin (RD) contains only the following repeating units (BP-A) and (BP-C) as bisphenol-derived repeating units. The polyarylate resin (RD) contains only the following repeating units (3), (DC-T) and (DC-I) as dicarboxylic acid-derived repeating units. Percentage of the number of repeating units (BP-A), percentage of the number of repeating units (BP-C), and percentage of the number of repeating units (3) to the total number of repeating units contained in the polyarylate resin (RD). , The percentage of the number of repeating units (DC-T), and the percentage of the number of repeating units (DC-I) are 25.0%, 25.0%, 25.0%, 15.0%, respectively. It is 10.0%.

The viscosity average molecular weights of the polyarylate resins (RA), (RB), (RC), and (RD) are 45,300, 51,000, 46,700, and respectively. It was 46,800.

<Composition of each polyarylate resin>
The composition of each of the polyarylate resins is shown in Table 3. Specifically, the types and ratios of bisphenol-derived repeating units of polyarylate resins (R-1) to (R-6) and (RA) to (RD), ratios n ₁ / n ₂ , and dicarboxylic acid-derived repeating units. The types of are shown in Table 3. "-" In Table 3 indicates that there is no corresponding value.

<Manufacturing of laminated photoconductor>
Next, laminated photoconductors (A-1) to (A-24) and (B-1) to (B-17) were produced by the following methods.

(Manufacturing of laminated photoconductor (A-1))
First, an intermediate layer was formed. Surface-treated titanium oxide (“Prototype SMT-A” manufactured by TAYCA CORPORATION, number average primary particle diameter 10 nm) was prepared. In SMT-A, titanium oxide was surface-treated with alumina and silica, and the surface-treated titanium oxide was further surface-treated with methylhydrogenpolysiloxane while being wet-dispersed. Next, 2 parts by mass of SMT-A and 1 part by mass of a polyamide resin ("Amilan (registered trademark) CM8000" manufactured by Toray Corporation, polyamide 6, polyamide 12, polyamide 66 and polyamide 610 quaternary copolymerized polyamide resin). , 10 parts by mass of methanol, 1 part by mass of butanol, and 1 part by mass of toluene were mixed for 5 hours using a bead mill to obtain a coating liquid for an intermediate layer. The coating liquid for the intermediate layer was filtered using a filter having an opening of 5 μm. Then, the coating liquid for the intermediate layer was applied to the surface of the conductive substrate by the dip coating method. As the conductive substrate, a drum-shaped support made of aluminum was used. Subsequently, the applied coating liquid for the intermediate layer was dried at 130 ° C. for 30 minutes to form an intermediate layer (thickness 1.5 μm) on the conductive substrate.

Next, a charge generation layer was formed. Specifically, 1.5 parts by mass of Y-type titanyl tetrahydrofuran, which is a charge generator, 1.0 part by mass of polyvinyl acetal resin (“Eslek BX-5” manufactured by Sekisui Chemical Co., Ltd.), which is a base resin, and propylene glycol monomethyl. 40.0 parts by mass of ether and 40.0 parts by mass of tetrahydrofuran were mixed using a bead mill for 12 hours to obtain a coating liquid for a charge generation layer. The coating liquid for the charge generation layer was filtered using a filter having an opening of 3 μm. The obtained filtrate was applied onto the intermediate layer by the dip coating method and dried at 50 ° C. for 5 minutes. In this way, a charge generation layer (thickness 0.3 μm) was formed on the intermediate layer.

Next, a charge transport layer was formed. Specifically, 45 parts by mass of the hole transport agent (HTM-1), 100 parts by mass of the polyarylate resin (R-1) which is a binder resin, 4 parts by mass of the azo compound (ADD-1), and 550 parts by mass of tetrahydrofuran. And 150 parts by mass of toluene were mixed to obtain a coating liquid for a charge transport layer. The coating liquid for the charge transport layer was applied onto the charge generating layer by the dip coating method, and dried at 120 ° C. for 40 minutes. In this way, a charge transport layer (thickness 20 μm) was formed on the charge generation layer to obtain a laminated photoconductor (A-1). In the laminated photoconductor (A-1), an intermediate layer was provided on the conductive substrate, a charge generation layer was provided on the intermediate layer, and a charge transport layer was provided on the charge generation layer.

(Laminated photoconductors (A-2) to (A-8), (A-12) to (A-24), (B-1) to (B-4), and (B-6) to (B). -16) Manufacturing)
The laminated photoconductor was produced in the same manner as in the production of the laminated photoconductor (A-1) except that the polyarylate resin, the hole transporting agent, and the azo compound or other compounds shown in Tables 4 and 5 were used. (A-2) to (A-8), (A-12) to (A-24), (B-1) to (B-4), and (B-6) to (B-16), respectively. Manufactured.

(Manufacturing of laminated photoconductors (A-9) to (A-11))
Laminated type by the same method as the production of the laminated photoconductor (A-1) except that 4 parts by mass of the azo compound (ADD-1) was changed to the amount of the azo compound (ADD-1) shown in Table 4. Each of the photoconductors (A-9) to (A-11) was produced.

(Manufacturing of laminated photoconductor (B-5))
The laminated photoconductor (B-5) was produced by the same method as that for the laminated photoconductor (A-1) except that the azo compound (ADD-1) was not added.

(Manufacturing of laminated photoconductor (B-17))
The laminated photoconductor was produced by the same method as that for producing the laminated photoconductor (A-1), except that 4 parts by mass of the azo compound (ADD-1) was changed to 7 parts by mass of the other compound (E-1). (B-17) was manufactured.

<Evaluation>
The laminated photoconductors (A-1) to (A-24) and (B-1) to (B-17), which are the photoconductors to be evaluated, were evaluated by the methods shown below. The evaluation machine used for each evaluation was a color printer (“C542dnw” manufactured by Oki Data Corporation). The toner cartridge of the evaluation machine was filled with cyan toner.

<Evaluation of wear resistance>
The film thickness T1 of the photosensitive layer (specifically, the charge transport layer) of the photoconductor was measured. Next, the photoconductor was mounted on the evaluation machine. Next, in an environment of a temperature of 23 ° C. and a relative humidity of 50% RH, Image I (a pattern image having a printing rate of 1%) was printed on 300,000 sheets of paper using an evaluation machine. After printing 300,000 sheets, the film thickness T2 of the photosensitive layer of the photoconductor was measured. Then, the amount of wear (T1-T2, unit: μm), which is the amount of change in the film thickness of the photosensitive layer before and after printing, was determined. The amount of wear is shown in Tables 4 and 5. From the amount of wear, the wear resistance of the photoconductor was evaluated according to the following criteria.
[Evaluation criteria for wear resistance]
Good: The amount of wear is 3.0 μm or less.
Defective: The amount of wear is over 3.0 μm.

<Evaluation of suppression of image defects caused by light exposure>
Light having an intensity of 1000 luxm using a white fluorescent lamp (“FL40SW” manufactured by NEC Lighting Co., Ltd.) as a light source was exposed to a part of the peripheral surface of the photoconductor (a region of 10 mm in length and 253 mm in width) for 1 hour. The area around the peripheral surface of the photoconductor exposed to light was defined as the light exposure area. The area around the peripheral surface of the photoconductor that was not exposed to light was defined as the non-light exposed area. Immediately after being exposed to light for 1 hour, the photoconductor was mounted on an evaluation machine, and Image II (halftone image with a printing rate of 50%) was printed on one sheet of paper using the evaluation machine. The printed image II was observed, and it was evaluated whether or not the occurrence of image defects due to light exposure was suppressed according to the following criteria. The evaluation results are shown in Tables 4 and 5.
[Evaluation criteria for suppressing the occurrence of image defects due to light exposure]
Evaluation A: No image density difference is confirmed between the image region corresponding to the light exposed region and the image region corresponding to the non-light exposed region.
Evaluation B: A slight difference in image density is confirmed between the image region corresponding to the light-exposed region and the image region corresponding to the non-light-exposed region.
Evaluation C: The difference in image density is clearly confirmed between the image region corresponding to the light-exposed region and the image region corresponding to the non-light-exposed region.

<Evaluation of suppression of image defects caused by contact with members of the image forming apparatus>
A photoconductor was mounted on an image drum (“DR-C4BC” manufactured by Oki Data Corporation), and a member (specifically, a charging roller) included in the image drum was brought into contact with a part of the peripheral surface of the photoconductor. .. Hereinafter, a part of the peripheral surface of the photoconductor in contact with the member will be referred to as a “member contact area”. Further, the region of the peripheral surface of the photoconductor that the members have not contacted is referred to as a “non-member contact region”. An image drum equipped with a photoconductor was allowed to stand for 4 weeks in an environment of a temperature of 50 ° C. and a relative humidity of 85% RH. Immediately after standing for 4 weeks, the photoconductor was mounted on an evaluation machine, and Image II (halftone image with a printing rate of 50%) was printed on one sheet of paper using the evaluation machine. The printed image II was observed, and it was evaluated whether or not the occurrence of image defects due to contact with the member included in the image forming apparatus was suppressed according to the following criteria. The evaluation results are shown in Tables 4 and 5.
[Evaluation criteria for suppressing the occurrence of image defects due to contact with members]
Evaluation A: No image density difference is confirmed between the image region corresponding to the member contact region and the image region corresponding to the non-member contact region.
Evaluation B: A slight difference in image density is confirmed between the image region corresponding to the member contact region and the image region corresponding to the non-member contact region.
Evaluation C: The difference in image density is clearly confirmed between the image region corresponding to the member contact region and the image region corresponding to the non-member contact region.

The terms in Tables 4 and 5 are as follows. “Photoreceptor” refers to a laminated photoconductor. "Resin" refers to a polyarylate resin. "HTM" refers to a hole transport agent. “Azo, etc.” refers to an azo compound or other compound. “Part” indicates a mass part. “Light exposure” in the “image evaluation” column indicates an evaluation of suppression of the occurrence of image defects caused by light exposure. “Member contact” in the “image evaluation” column indicates an evaluation of suppressing the occurrence of image defects due to contact with a member included in the image forming apparatus. “Not dissolved” indicates that the binder resin did not dissolve in the solvent and the charge transport layer could not be formed during the preparation of the coating liquid for the charge transport layer. "-" Indicates that the corresponding material was not added.

The photosensitive layers (more specifically, the charge generating layer) of the laminated photoconductors (A-1) to (A-24) contained a charge generating agent. As shown in Table 4, the photosensitive layers (more specifically, the charge transporting layer) of the laminated photoconductors (A-1) to (A-24) are a hole transporting agent and a binder resin (more specifically). The polyarylate resin (R-1) to (R-6)) and the azo compound (more specifically, any of the azo compounds (ADD-1) to (ADD-8)). Was contained. As shown in Table 3, the polyarylate resins (R-1) to (R-6) all include a repeating unit (1), a repeating unit (2), and a repeating unit (3), and are repeated. The ratio n ₁ / n ₂ of the number n ₁ of the repeating unit (1) to the number n ₂ of the unit (2) was 1.0 or more. All of the azo compounds (ADD-1) to (ADD-8) were compounds included in the general formula (10).

As shown in Table 4, the amount of wear of the laminated photoconductors (A-1) to (A-24) is 3.0 μm or less, and the laminated photoconductors (A-1) to (A-24) have a wear amount of 3.0 μm or less. It had excellent wear resistance. In addition, the evaluation of suppression of image defects caused by light exposure of the laminated photoconductors (A-1) to (A-24) was A, and the occurrence of image defects caused by light exposure was suppressed. The evaluation of suppressing the occurrence of image defects due to contact with the members of the image forming apparatus of the laminated photoconductors (A-1) to (A-24) is A, and the evaluation of the suppression of image defects due to contact with the members is A. The outbreak was suppressed.

From the above, it was shown that the photoconductor according to the present invention has excellent wear resistance and can suppress the occurrence of image defects due to light exposure and image defects due to contact with a member included in the image forming apparatus. ..

The photoconductor according to the present invention can be used in an image forming apparatus.

1: Laminated photoconductor (laminated electrophotographic photosensitive member)
2: Conductive substrate 3: Photosensitive layer 3a: Charge generation layer 3b: Charge transport layer 3c: Single layer type photosensitive layer 10: Single layer type photoconductor (single layer type electrophotographic photosensitive member)

Claims (9)

It is provided with a conductive substrate and a photosensitive layer,
The photosensitive layer contains a charge generator, a hole transport agent, a binder resin, and an azo compound.
The binder resin contains a polyarylate resin, and the polyallylate resin is represented by a repeating unit represented by the general formula (1), a repeating unit represented by the chemical formula (2), and a chemical formula (3). The ratio n ₁ / n ₂ of the number n ₁ of the repeating units represented by the general formula (1) to the number n ₂ of the repeating units represented by the chemical formula (2) including the repeating unit is 1. It is 0 or more,
The azo compound is an electrophotographic photosensitive member represented by the general formula (10).

(In the general formula (1),
R ¹ and R ² each independently represent a hydrogen atom or a methyl group, R ³ represents a methyl group, R ⁴ represents a hydrogen atom or an alkyl group having 2 or 3 carbon atoms, or
R ¹ and R ² represent a methyl group, respectively, and R ³ and R ⁴ are bonded to each other to represent a cycloalkylidene group having 5 or 6 carbon atoms. )

(In the general formula (10),
R ¹¹ and R ¹² each independently represent an alkyl group having 1 or more and 3 or less carbon atoms.
Ar ¹ and Ar ² each independently represent an arylene group having 6 or more and 14 or less carbon atoms which may be substituted with at least one substituent, and the substituent is an alkyl group having 1 or more and 3 or less carbon atoms. And selected from the group consisting of alkoxy groups having 1 or more and 3 or less carbon atoms.
Q represents a monovalent group represented by the general formula (Q1) or (Q2). )

(In the general formula (Q1), Ar ³ and Ar ⁴ each independently represent an aryl group having 6 or more and 14 or less carbon atoms which may be substituted with an alkyl group having 1 or more and 3 or less carbon atoms.
In the general formula (Q2), Z represents a heterocycle having at least 6 or more and 18 or less members having a nitrogen atom as a ring-constituting atom. ) The repeating unit represented by the general formula (1) is a chemical formula (1-1), a chemical formula (1-2), a chemical formula (1-3), a chemical formula (1-4), or a chemical formula (1-5). The electrophotographic photosensitive member according to claim 1, which is a repeating unit represented.

The electrophotographic photosensitive member according to claim 1 or 2, wherein the azo compound contains at least one compound among the compounds represented by the chemical formulas (ADD-1) to (ADD-8).

The electrophotographic photosensitive member according to any one of claims 1 to 3, wherein the content of the azo compound is 2 parts by mass or more and 5 parts by mass or less with respect to 100 parts by mass of the binder resin. The electrophotographic photosensitive member according to any one of claims 1 to 4, wherein the hole transporting agent contains at least one compound among the compounds represented by the general formulas (20) to (22).

(In the general formula (20), R ²¹ and R ²² each independently represent an alkyl group having 1 or more and 8 or less carbon atoms, a phenyl group, or an alkoxy group having 1 or more and 8 or less carbon atoms, and R ^23. And R ²⁴ are each independently a phenyl group, a hydrogen atom, an alkyl group having 1 or more and 8 or less carbon atoms, or an alkyl group having 1 or more and 8 or less carbon atoms, which may be substituted with an alkyl group having 1 or more and 8 or less carbon atoms. R ²⁵ , R ²⁶ , R ²⁷ , R ²⁸ , and R ²⁹ each independently represent a hydrogen atom, an alkyl group having 1 or more and 8 or less carbon atoms, a phenyl group, or 1 or more carbon atoms. Representing an alkoxy group of 8 or less, two adjacent two of R ²⁵ , R ²⁶ , R ²⁷ , R ²⁸ , and R ²⁹ may be bonded to represent a ring, where a1 and a2 are independently 0. Represents an integer of 5 or more and 5 or less
In the general formula (21), R ^{31 to} R ³⁶ each independently represent an alkyl group or a phenyl group having 1 or more and 8 or less carbon atoms, and R ³⁷ and R ³⁸ each independently represent a hydrogen atom. Represents an alkyl group or phenyl group having 1 or more and 8 or less carbon atoms, b1, b2, b3, and b4 each independently represent an integer of 0 or more and 5 or less, and b5 and b6 each independently represent 0. It represents an integer of 4 or more, and d and e independently represent 0 or 1, respectively.
In the general formula (22), R ^{41 to} R ⁴⁶ independently represent an alkyl group having 1 or more and 8 or less carbon atoms, a phenyl group, or an alkoxy group having 1 or more and 8 or less carbon atoms, and f1 and f2. , F4, and f5 each independently represent an integer of 0 or more and 5 or less, and f3 and f6 each independently represent an integer of 0 or more and 4 or less. ) In the general formula (20), R ²¹ and R ²² independently represent an alkyl group having 1 or more and 8 or less carbon atoms, and R ²³ and R ²⁴ independently represent 1 or more and 8 or less carbon atoms, respectively. Represents a phenyl group or a hydrogen atom which may be substituted with an alkyl group of, and R ²⁵ , R ²⁶ , R ²⁷ , R ²⁸ , and R ²⁹ are each independently a hydrogen atom and having 1 or more and 8 or less carbon atoms. Represents an alkyl group or an alkoxy group having 1 or more and 8 or less carbon atoms, and two adjacent two of R ²⁵ , R ²⁶ , R ²⁷ , R ²⁸ , and R ²⁹ are bonded to each other and have 5 or more and 7 or less carbon atoms. It may represent cycloalkoxy, where a1 and a2 independently represent 0 or 1, respectively.
In the general formula (21), R ^{31 to} R ³⁶ each independently represent an alkyl group having 1 or more and 8 or less carbon atoms, and R ³⁷ and R ³⁸ each independently represent a hydrogen atom or a phenyl group. B1, b2, b3, and b4 each independently represent an integer of 0 or more and 2 or less, b5 and b6 each represent 0, and d and e each independently represent 0 or 1. ,
In the general formula (22), R ^{41 to} R ⁴⁶ each independently represent an alkyl group having 1 or more and 8 or less carbon atoms, and f1, f2, f4, and f5 each independently represent 0 or more and 2 or less. The electrophotographic photosensitive member according to any one of claims 1 to 5, wherein f3 and f6 each represent an integer of 0. The electrophotographic photosensitive member according to any one of claims 1 to 6, wherein the hole transporting agent is at least one compound among the compounds represented by the chemical formulas (HTM-1) to (HTM-9). body.

The photosensitive layer includes a charge generating layer and a charge transporting layer.
The charge generating layer contains the charge generating agent and contains the charge generating agent.
The electrophotographic photosensitive member according to any one of claims 1 to 7, wherein the charge transport layer contains the hole transport agent, the binder resin, and the azo compound. The electrophotographic photosensitive member according to claim 8, wherein the charge transport layer is provided as one layer and as the outermost surface layer.

Images