JP2020181012A - Electrophotographic photoreceptor - Google Patents

Abstract

To provide an electrophotographic photoreceptor that is excellent in wear resistance and can prevent passing of toner and the like at a contact part with a cleaning blade.SOLUTION: A photosensitive layer 3 of an electrophotographic photoreceptor 1 contains at least a charge generating agent, a first hole transport agent, a second hole transport agent, and a binder resin. The binder resin contains a polyarylate resin. The polyarylate resin includes a repeating unit (1), a repeating unit (2), and a repeating unit (3). The ratio of the number n1 of the repeating units (1) to the number n2 of the repeating units (2), n1/n2 is 1.0 or more. The first hole transport agent is at least one compound of compounds represented by specific general formulas. The second hole transport agent is at least one compound of compounds represented by specific general formulas. The ratio of the mass of the first hole transport agent to the mass of the second hole transport agent is 1.0 or more and 3.0 or less.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 have excellent wear resistance and allow toner and a toner external agent (hereinafter referred to as toner or the like) to slip through a contact portion with a cleaning blade. It is to provide an electrophotographic photosensitive member which can suppress such a thing.

The electrophotographic photosensitive member of the present invention includes a conductive substrate and a photosensitive layer. The photosensitive layer contains at least a charge generating agent, a first hole transporting agent, a second hole transporting agent, and a binder resin. 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 first hole transporting agent is at least one compound among the compounds represented by the general formulas (20) to (23). The second hole transporting agent is at least one compound among the compounds represented by the general formulas (24) and (25). The ratio of the mass of the first hole transporting agent to the mass of the second hole transporting agent is 1.0 or more and 3.0 or less.

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 (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 (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 (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 (23), R ^{51 to} R ⁵⁵ each independently represent an alkyl group having 1 to 8 carbon atoms or an alkoxy group having 1 to 8 carbon atoms. g1, g2, g3, g4, and g5 each independently represent an integer of 0 or more and 5 or less.

In the general formula (24), R ^{61 to} R ⁶³ independently represent an alkyl group having 1 to 8 carbon atoms or an alkoxy group having 1 to 8 carbon atoms. R ⁶⁴ and R ⁶⁵ each independently represent a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, or an aryl group having 6 to 14 carbon atoms. k1 and k2 each independently represent an integer of 0 or more and 5 or less, and k3 represents an integer of 0 or more and 4 or less. In the general formula (25), R ^{71 to} R ⁷⁴ independently represent an alkyl group having 1 to 8 carbon atoms or an alkoxy group having 1 to 8 carbon atoms. r1, r2, r3, and r4 each independently represent an integer of 0 or more and 5 or less.

The electrophotographic photosensitive member of the present invention has excellent wear resistance and can suppress the slip-through of toner or the like at the contact portion with the cleaning blade.

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. Examples of the halogen atom (halogen group) include a fluorine atom (fluoro group), a chlorine atom (chloro group), a bromine atom (bromo group), and an iodine atom (iodine group).

Alkyl groups with 1 to 8 carbon atoms, alkyl groups with 1 to 6 carbon atoms, alkyl groups with 1 to 5 carbon atoms, alkyl groups with 1 to 4 carbon atoms, 1 to 3 carbon atoms The following alkyl groups, alkyl groups having 2 carbon atoms, and alkyl groups having 3 carbon atoms are linear or branched and unsubstituted, respectively, 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. Alkyl group with 1 to 6 carbon atoms, alkyl group with 1 to 5 carbon atoms, alkyl group with 1 to 4 carbon atoms, alkyl group with 1 to 3 carbon atoms, alkyl with 2 carbon atoms Examples of the group and the alkyl group having 3 carbon atoms are the groups having the corresponding carbon atom number among the groups described as examples of the alkyl group having 1 or more and 8 or less carbon atoms, respectively.

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. 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 at least a charge generator, a first hole transporting agent, a second hole transporting agent, and a binder resin. 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 a charge transport layer 3b containing a polyarylate resin (PA), a first hole transport agent, and a second hole transport agent, which will be described later, as the outermost surface layer, the wear resistance of the laminated photoconductor 1 can be improved. It can be further improved and the slip-through of toner or the like at the contact portion with the cleaning blade can be further suppressed.

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 first hole transport agent, a second hole transport agent, and a binder resin. The charge transport layer 3b may further contain a third compound described later, if necessary. 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. The single-layer photosensitive layer 3c containing the polyarylate resin (PA), the first hole transporting agent, and the second hole transporting agent, which will be described later, is provided as the outermost surface layer, whereby the resistance of the single-layer photosensitive member 10 is increased. The wear resistance can be further improved, and the slip-through of toner or the like at the contact portion with the cleaning blade can be further suppressed.

The single-layer photosensitive layer 3c contains a charge generator, a first hole transporting agent, a second hole transporting agent, and a binder resin. 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.

(Hole transport agent)
The photosensitive layer contains at least two types of hole transporting agents, a first hole transporting agent and a second hole transporting agent. Hereinafter, the first hole transporting agent and the second hole transporting agent will be described in detail.

[First hole transport agent]
When the photosensitive layer contains the first hole transporting agent, the following advantages can be obtained. Generally, when the binder resin contains a hole transporting agent, the wear resistance of the binder resin tends to decrease. However, the first hole transporting agent having a predetermined structure does not easily reduce the abrasion resistance of the polyarylate resin (PA). Therefore, since the first hole transporting agent is contained in the photosensitive layer, the abrasion resistance of the photoconductor improved by the polyarylate resin (PA) can be maintained.

The inclusion of the first hole transport agent in the photosensitive layer also provides the following other advantages. If printing is continued using the image forming apparatus, the moving rate of holes between the hole transporting agent molecules may decrease. Here, the first hole transporting agent has a relatively large molecular weight and has a predetermined structure. When the photosensitive layer contains such a first hole transporting agent, the number of times the holes generated during exposure move (hopping) between the hole transporting agent molecules is reduced, and the holes move between the molecules. The effect of slowing down is reduced. As a result, the electrical characteristics of the photoconductor can be maintained even when printing is continued using the image forming apparatus.

The first hole transporting agent is at least one compound (for example, one compound) among the compounds represented by the general formulas (20), (21), (22), and (23). Hereinafter, the compounds represented by the general formulas (20) to (23) may be described as the first hole transporting agents (20) to (23), 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.

In the general formula (23), R ^{51 to} R ⁵⁵ each independently represent an alkyl group having 1 or more and 8 or less carbon atoms or an alkoxy group having 1 or more and 8 or less carbon atoms. g1, g2, g3, g4, and g5 each independently represent an integer of 0 or more and 5 or less.

In the general formula (23), when g1 represents an integer of 2 or more and 5 or less, a plurality of R ^51s may be the same as each other or may be different from each other. When g2 represents an integer of 2 or more and 5 or less, a plurality of R ^52s may be the same as each other or may be different from each other. When g3 represents an integer of 2 or more and 5 or less, a plurality of R ^53s may be the same as each other or may be different from each other. When g4 represents an integer of 2 or more and 5 or less, the plurality of R ^54s may be the same as or different from each other. When g5 represents an integer of 2 or more and 5 or less, the plurality of R ^55s may be the same as or different from each other.

In the general formula (23), R ^{51 to} R ⁵⁵ 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 g1, g2, g3, g4, and g5 each independently represent 0 or 1.

The first 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-11). Hereinafter, the compounds represented by the chemical formulas (HTM-1) to (HTM-11) may be described as the first hole transporting agents (HTM-1) to (HTM-11), respectively.

The first hole transporting agents (HTM-1) to (HTM-4) are each suitable examples of the first hole transporting agent (20). The first hole transporting agents (HTM-5) to (HTM-7) are each suitable examples of the first hole transporting agent (21). The first hole transporting agents (HTM-8) to (HTM-9) are each suitable examples of the first hole transporting agent (22). The first hole transporting agents (HTM-10) to (HTM-11) are each suitable examples of the first hole transporting agent (23).

[Second hole transport agent]
The second hole transport agent has a relatively small molecular weight and has a predetermined structure. Such a second hole transporting agent enters the minute voids of the photosensitive layer, and elasticity is imparted to the photosensitive layer. Therefore, since the photosensitive layer contains the second hole transporting agent, the slip-through of toner or the like at the contact portion with the cleaning blade is suppressed. By containing the first hole transporting agent and the polyarylate resin (PA) in the photosensitive layer in addition to the second hole transporting agent, slip-through of toner or the like at the contact portion with the cleaning blade is further suppressed. ..

The second hole transporting agent is at least one compound (for example, one compound) among the compounds represented by the general formulas (24) and (25). Hereinafter, the compounds represented by the general formulas (24) and (25) may be referred to as the second hole transporting agents (24) and (25), respectively.

In the general formula (24), R ^{61 to} R ⁶³ independently represent an alkyl group having 1 or more and 8 or less carbon atoms or an alkoxy group having 1 or more and 8 or less carbon atoms. R ⁶⁴ and R ⁶⁵ each independently represent a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, or an aryl group having 6 to 14 carbon atoms. Each of k1 and k2 independently represents an integer of 0 or more and 5 or less. k3 represents an integer of 0 or more and 4 or less.

When k1 represents an integer of 2 or more and 5 or less, a plurality of R ^61s may be the same as each other or may be different from each other. When k2 represents an integer of 2 or more and 5 or less, a plurality of R ^62s may be the same as each other or may be different from each other. When k3 represents an integer of 2 or more and 4 or less, a plurality of R ^63s may be the same as each other or may be different from each other.

In the general formula (24), R ^{61 to} R ⁶³ 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. R ⁶⁴ and R ⁶⁵ each independently preferably represent an alkyl group having 1 to 8 carbon atoms, more preferably an alkyl group having 1 to 3 carbon atoms, and more preferably a methyl group. More preferred. It is preferable that k1 and k2 each represent 1. k3 preferably represents 0.

In the general formula (25), R ^{71 to} R ⁷⁴ independently represent an alkyl group having 1 or more and 8 or less carbon atoms or an alkoxy group having 1 or more and 8 or less carbon atoms. r1, r2, r3, and r4 each independently represent an integer of 0 or more and 5 or less.

When r1 represents an integer of 2 or more and 5 or less, a plurality of R ^71s may be the same as each other or may be different from each other. When r2 represents an integer of 2 or more and 5 or less, a plurality of R ^72s may be the same as or different from each other. When r3 represents an integer greater than or equal to 2 and less than or equal to 5, the plurality of R ^73s may be the same as or different from each other. When r4 represents an integer of 2 or more and 5 or less, a plurality of R ^74s may be the same as each other or may be different from each other.

In the general formula (25), R ^{71 to} R ⁷⁴ 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 r1, r2, r3, and r4 independently represent 0 or 1, respectively.

The second hole transporting agent is preferably at least one compound (for example, one compound) among the compounds represented by the chemical formulas (HTM-12) and (HTM-13). Hereinafter, the compounds represented by the chemical formulas (HTM-12) and (HTM-13) may be described as the second hole transporting agent (HTM-12) and (HTM-13), respectively.

The second hole transporting agent (HTM-12) is a suitable example of the second hole transporting agent (24). The second hole transport agent (HTM-13) is a good example of the second hole transport agent (25).

[Ratio W1 / W2]
The ratio W1 / W2 of the mass W1 of the first hole transporting agent to the mass W2 of the second hole transporting agent is 1.0 or more and 3.0 or less. When the ratio W1 / W2 is less than 1.0, the content of the first hole transporting agent is small and the abrasion resistance of the photoconductor is lowered. When the ratio W1 / W2 is larger than 3.0, the content of the second hole transporting agent is small, and toner or the like slips through at the contact portion with the cleaning blade. The ratio W1 / W2 is preferably 1.5 or more and 2.5 or less in order to improve the wear resistance of the photoconductor and suppress the slip-through of toner or the like at the contact portion with the cleaning blade. When two or more kinds of first hole transporting agents are contained in the photosensitive layer, the mass W1 of the first hole transporting agent is the total mass of the two or more kinds of first hole transporting agents. When two or more kinds of second hole transporting agents are contained in the photosensitive layer, the mass W2 of the second hole transporting agent is the total mass of the two or more kinds of second hole transporting agents.

[Other hole transporters]
The photosensitive layer may contain only the first hole transporting agent and the second hole transporting agent as the hole transporting agent. Further, in the photosensitive layer, as the hole transporting agent, in addition to the first hole transporting agent and the second hole transporting agent, other hole transporting agents (hereinafter, other hole transporting agents) may be described. Yes) may be further contained.

Examples of other hole transporting agents include triphenylamine derivatives and diamine derivatives (for example, N, N, N', N'-tetraphenylbenzidine derivatives, N, N, N', N'-tetraphenylphenylenediamine. Derivatives, N, N, N', N'-tetraphenylnaphthylene diamine derivatives, N, N, N', N'-tetraphenylphenanthrylene diamine derivatives, and di (aminophenylethenyl) benzene derivatives), oxa Diazole compounds (eg 2,5-di (4-methylaminophenyl) -1,3,4-oxadiazole), styryl compounds (eg 9- (4-diethylaminostyryl) anthracene), carbazole compounds Compounds (eg, polyvinylcarbazole), organic polysilane compounds, pyrazoline compounds (eg, 1-phenyl-3- (p-dimethylaminophenyl) pyrazoline), hydrazone compounds, indol compounds, oxazole compounds, isooxazole compounds , Thiazol-based compounds, thiadiazol-based compounds, imidazole-based compounds, pyrazole-based compounds, and triazole-based compounds.

When the photoconductor is a laminated photoconductor, the content of the hole transporting agent (for example, the total content of the first hole transporting agent and the second hole transporting agent) is determined with respect to 100 parts by mass of the binder resin. It is preferably 10 parts by mass or more and 200 parts by mass or less, more preferably 20 parts by mass or more and 100 parts by mass or less, and further 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 (for example, the total content of the first hole transporting agent and the second hole transporting agent) is based on 100 parts by mass of the binder resin. , 50 parts by mass or more and preferably 200 parts by mass or less.

(Third compound)
The third compound is contained in the charge transport layer, for example, as an electron acceptor compound. The third compound has a ketone structure or a dicyanomethylene structure. By containing the third compound in the charge transport layer, it is possible to improve the electrical characteristics of the photoconductor while improving the wear resistance of the photoconductor and suppressing the slip-through of toner and the like. In particular, it is possible to improve the electrical characteristics of the photoconductor before printing using the image forming apparatus, and to suppress a decrease in the electrical characteristics when printing is continued using the image forming apparatus.

The third compound is preferably at least one compound (for example, one compound) among the compounds represented by the general formulas (31) to (39). Hereinafter, the compounds represented by the general formulas (31) to (39) may be described as the third compounds (31) to (39), respectively.

In the general formula (31) ~ (39), Q 31 ~Q 57 are each independently a hydrogen atom, a halogen atom, an alkyl group having 1 to 5 carbon atoms, 6 or more carbon atoms 14 in the following aryl group It represents an alkoxy group having 1 or more and 3 or less carbon atoms which may be substituted, or an alkyl group having 1 or more and 3 or less carbon atoms or a phenyl group which may be substituted with an alkoxy group having 1 to 3 carbon atoms.

As the halogen atom represented by Q ^{31 to} Q ⁵⁷ in the general formulas (31) to (39), a chlorine atom is preferable.

Examples of the alkyl group having 1 or more and 5 or less carbon atoms represented by Q ^{31 to} Q ⁵⁷ in the general formulas (31) to (39) include a methyl group, an ethyl group, an n-butyl group, a tert-butyl group, or 1, A 1-dimethylpropyl group is preferred.

The methoxy group is preferable as the alkoxy group having 1 or more and 3 or less carbon atoms represented by Q ^{31 to} Q ⁵⁷ in the general formulas (31) to (39). The alkoxy group having 1 or more and 3 or less carbon atoms may be substituted with an aryl group having 6 or more and 14 or less carbon atoms. A phenyl group is preferable as the aryl group having 6 to 14 carbon atoms, which is a substituent of the alkoxy group having 1 to 3 carbon atoms. A phenylmethoxy group is preferable as the alkoxy group having 1 or more and 3 or less carbon atoms substituted with an aryl group having 6 or more and 14 or less carbon atoms.

The phenyl group represented by Q ^{31 to} Q ⁵⁷ in the general formulas (31) to (39) may be substituted with an alkyl group having 1 or more and 3 or less carbon atoms or an alkoxy group having 1 or more and 3 or less carbon atoms. As the alkyl group having 1 or more and 3 or less carbon atoms, which is a substituent of the phenyl group, a methyl group or an ethyl group is preferable.

Formula ⁽³¹⁾ Q 31 ~Q ³⁴ in each preferably represents an alkyl group having 1 to 5 carbon atoms, more preferably represents an alkyl group having 1 to 4 carbon atoms, methyl It is more preferred to represent a group or a tert-butyl group.

Q ³⁵ to Q ³⁸ in formula (32) are each preferably represents an alkyl group having 1 to 5 carbon atoms, more preferably represents an alkyl group having 1 to 4 carbon atoms, methyl It is more preferred to represent a group or a tert-butyl group.

Formula (33) Q ³⁹ ~Q ⁴⁰ in each, preferably represents an an alkyl group having 1 to 5 carbon atoms, and more preferably represents a 1,1-dimethylpropyl group.

Q ⁴¹ to Q ⁴² in formula (34) are each preferably represents an alkyl group having 1 to 5 carbon atoms, more preferably represents an alkyl group having 1 to 4 carbon atoms, tert -It is more preferable to represent a butyl group. Q ⁴³ to Q ⁴⁷ each independently preferably represents a hydrogen atom or a halogen atom, and more preferably represents a hydrogen atom or a chlorine atom. It is preferable that Q ⁴³ , Q ⁴⁴ , Q ⁴⁶ , and Q ⁴⁷ each represent a hydrogen atom. Q ⁴⁵ is preferably a halogen atom, more preferably a chlorine atom.

Each of Q ^{48 to} Q ⁵¹ in the general formula (35) preferably represents an alkyl group having 1 or more and 5 or less carbon atoms, and more preferably represents an alkyl group having 1 or more and 4 or less carbon atoms. -It is more preferable to represent a butyl group.

Formula (36) Q ⁵² ~Q ⁵³ in each preferably represent a phenyl group substituted with a carbon atom number of 1 to 3 having an alkyl group or a carbon atom 1 to 3 alkoxy groups, 1 It is more preferable to represent a phenyl group substituted with one or two alkyl groups having 1 or more carbon atoms and 3 or less carbon atoms, and further preferably to represent a 2-ethyl-6-methylphenyl group.

Q ⁵⁴ in formula (37), preferably represents an alkyl group having 1 to 5 carbon atoms, more preferably represents an alkyl group having 1 to 4 carbon atoms, represents a n- butyl group Is even more preferable.

It is preferable that Q ^{55 to} Q ⁵⁶ in the general formula (38) each represent a hydrogen atom.

Q ⁵⁷ in the general formula (39) preferably represents an alkoxy group having 1 or more and 3 or less carbon atoms substituted with an aryl group having 6 or more and 14 or less carbon atoms, and preferably has the number of carbon atoms substituted with a phenyl group. It is more preferable to represent an alkoxy group of 1 or more and 3 or less, and further preferably to represent a phenylmethoxy group.

The third compound is preferably at least one compound (for example, one compound) among the compounds represented by the chemical formulas (E-1) to (E-11). Hereinafter, the compounds represented by the chemical formulas (E-1) to (E-11) may be described as the third compounds (E-1) to (E-11), respectively.

The third compounds (E-1) to (E-2) are each preferable examples of the third compound (31). Each of the third compounds (E-3) to (E-4) is a suitable example of the third compound (32). The third compound (E-5) is a good example of the third compound (33). The third compound (E-6) is a good example of the third compound (34). The third compound (E-7) is a good example of the third compound (35). The third compound (E-8) is a good example of the third compound (36). The third compound (E-9) is a good example of the third compound (37). The third compound (E-10) is a good example of the third compound (38). The third compound (E-11) is a good example of the third compound (39).

The charge transport layer may contain only the third compound as the electron acceptor compound, or may further contain other electron acceptor compounds. The content of the third compound is preferably 0.1 part by mass or more and 10.0 parts by mass or less, and 0.5 parts by mass or more and 5.0 parts by mass or less with respect to 100 parts by mass of the binder resin. Is more preferable.

(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 charge generation layer may contain a base resin. The example of the base resin is the same as the example of other binder resins 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 wear resistance of the photoconductor and prevent the toner and the like from slipping through at the contact portion with the cleaning blade, a combination of a polyarylate resin, a first hole transporting agent, and a second hole transporting agent is used. , Combination No. shown in Table 1. It is preferably each of F1 to F44. For the same reason, the combinations of the polyarylate resin, the first hole transporting agent, and the second hole transporting agent are the combinations No. 1 shown in Table 1. It is each of F1 to F44, and it is more preferable that the charge generator is Y-type titanylphthalocyanine.

In order to improve the wear resistance of the photoconductor and prevent the toner and the like from slipping through at the contact portion with the cleaning blade, the polyarylate resin, the first hole transporting agent, the second hole transporting agent, and the third hole transporting agent are used. The combination of the compounds is the combination No. 2 shown in Tables 2 and 3. It is preferably each of G1 to G84. For the same reason, the combinations of the polyarylate resin, the first hole transporting agent, the second hole transporting agent, and the third compound are the combination numbers shown in Tables 2 and 3. It is each of G1 to G84, and it is more preferable that the charge generator is Y-type titanylphthalocyanine.

The meanings of the terms in Tables 1 to 3 above are as follows. "No." indicates "combination No.". "Resin" indicates "polyarylate resin". "First HTM" refers to "first hole transporter". "Second HTM" refers to "second 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 first hole transport agent, a second hole transport agent, a binder resin, and a solvent. The coating liquid for the charge transport layer can be prepared by dissolving or dispersing the first hole transport agent, the second hole transport agent, 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 type photosensitive layer contains, for example, a charge generator, a first hole transporting agent, a second hole transporting agent, a binder resin, and a solvent. The coating liquid for a single-layer type photosensitive layer is prepared by dissolving or dispersing a charge generator, a first hole transporting agent, a second hole transporting agent, 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 first hole transporting agent, the first hole transporting agents (HTM-1) to (HTM-11) described in the embodiment were prepared. As the second hole transporting agent, the second hole transporting agent (HTM-12) and (HTM-13) described in the embodiment were prepared.

<Preparation of the third compound>
As the third compound, the third compounds (E-1) to (E-11) described in the embodiment were prepared.

<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 4. 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 4. “-” In Table 4 indicates that there is no corresponding value.

<Manufacturing of laminated photoconductor>
Next, laminated photoconductors (A-1) to (A-29) and (B-1) to (B-8) 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, 30.0 parts by mass of the first hole transporting agent (HTM-1), 15.0 parts by mass of the second hole transporting agent (HTM-12), and a polyallylate resin (R-1) which is a binder resin. ) 100.0 parts by mass, 2.0 parts by mass of the third compound (E-1), 550.0 parts by mass of tetrahydrofuran, and 150.0 parts by mass of toluene are mixed to prepare a coating liquid for a charge transport layer. Obtained. 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.

(Manufacturing of laminated photoconductors (A-2) to (A-27) and (B-1) to (B-4))
The same method as for producing the laminated photoconductor (A-1) except that the first hole transporting agent, the second hole transporting agent, the binder resin, and the third compound shown in Tables 5 and 6 were used. , Each of the laminated photoconductors (A-2) to (A-27) and (B-1) to (B-4) was produced.

(Manufacturing of laminated photoconductor (A-28))
30.0 parts by mass of the first hole transporting agent (HTM-1) and 15.0 parts by mass of the second hole transporting agent (HTM-12), 22.5 parts by mass of the first hole transporting agent (HTM-1) The laminated photoconductor (A-28) was manufactured in the same manner as the laminated photoconductor (A-1), except that the portion and the second hole transporting agent (HTM-12) were changed to 22.5 parts by mass. Manufactured.

(Manufacturing of laminated photoconductor (A-29))
30.0 parts by mass of the first hole transporting agent (HTM-1) and 15.0 parts by mass of the second hole transporting agent (HTM-12), 33.8 parts by mass of the first hole transporting agent (HTM-1) The laminated photoconductor (A-29) was manufactured in the same manner as the laminated photoconductor (A-1), except that the portion and the second hole transporting agent (HTM-12) were changed to 11.2 parts by mass. Manufactured.

(Manufacturing of laminated photoconductor (B-5))
30.0 parts by mass of the first hole transporting agent (HTM-1) and 15.0 parts by mass of the second hole transporting agent (HTM-12), 45.0 parts by mass of the second hole transporting agent (HTM-12) The laminated photoconductor (B-5) was manufactured by the same method as that for the laminated photoconductor (A-1) except that the parts were changed. In the production of the laminated photoconductor (B-5), the first hole transporting agent (HTM-1) was not added.

(Manufacturing of laminated photoconductor (B-6))
30.0 parts by mass of the first hole transporting agent (HTM-1) and 15.0 parts by mass of the second hole transporting agent (HTM-12), 15.0 parts by mass of the first hole transporting agent (HTM-1) The laminated photoconductor (B-6) was manufactured in the same manner as the laminated photoconductor (A-1) except that the portion and the second hole transporting agent (HTM-12) were changed to 30.0 parts by mass. Manufactured.

(Manufacturing of laminated photoconductor (B-7))
30.0 parts by mass of the first hole transporting agent (HTM-1) and 15.0 parts by mass of the second hole transporting agent (HTM-12), 36.0 parts by mass of the first hole transporting agent (HTM-1) The laminated photoconductor (B-7) was manufactured in the same manner as in the production of the laminated photoconductor (A-1), except that the portion and the second hole transporting agent (HTM-12) were changed to 9.0 parts by mass. Manufactured.

(Manufacturing of laminated photoconductor (B-8))
30.0 parts by mass of the first hole transporting agent (HTM-1) and 15.0 parts by mass of the second hole transporting agent (HTM-12), 45.0 parts by mass of the first hole transporting agent (HTM-1) The laminated photoconductor (B-8) was manufactured by the same method as that for the laminated photoconductor (A-1) except that the parts were changed. The second hole transport agent (HTM-12) was not added in the production of the laminated photoconductor (B-8).

<Evaluation>
The laminated photoconductors (A-1) to (A-29) and (B-1) to (B-8), which are the photoconductors to be evaluated, were evaluated by the methods shown below.

<Evaluation of wear resistance>
The evaluation machine used for the evaluation of wear resistance was a color printer (“C542dnw” manufactured by Oki Data Corporation). The toner cartridge of the evaluation machine was filled with cyan toner. First, 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 7 and 8. 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 slip-through of toner, etc.>
After the above <evaluation of wear resistance> was completed, the evaluation machine was moved to a high temperature and high humidity environment (temperature 32.5 ° C. and relative humidity 85%). Image II (solid image with a printing rate of 70%) was printed on 10,000 sheets of paper in a high-temperature and high-humidity environment using an evaluation machine. Then, in a high temperature and high humidity environment, an image III (a halftone image having a printing rate of 40%, hereinafter referred to as an evaluation image) was printed on one sheet of paper using an evaluation machine. The printed evaluation image was observed, and the number of black spots and white spots having a diameter of 0.3 mm or more was counted. Then, it was evaluated whether or not the slip-through of toner or the like was suppressed according to the following criteria. The evaluation results are shown in Tables 7 and 8.

[Evaluation criteria for suppressing slip-through of toner, etc.]
Evaluation A (good): The total number of white spots and black spots confirmed in the evaluation image is 0.
Evaluation B (slightly defective): The total number of white spots and black spots confirmed in the evaluation image is 1 or more and 10 or less.
Evaluation C (defective): The total number of white spots and black spots confirmed in the evaluation image is 11 or more.

When the toner or the like slips through the contact portion between the photoconductor and the cleaning blade and the toner or the like adheres to the back side of the cleaning blade, the following image defects tend to occur in the formed image. Specifically, the amount of toner or the like adhering to the back side of the cleaning blade increases, the toner or the like drops from the back side of the cleaning blade to the charging roller, and the toner or the like adheres to the charging roller, causing black spots in the formed image.

Further, when the toner or the like slips through the contact portion between the photoconductor and the cleaning blade and the toner or the like remains on the surface of the photoconductor, the following image defects tend to occur in the formed image. Specifically, toner is further supplied to the surface region of the photoconductor in which toner remains (hereinafter referred to as residual region) during development, and toner thicker than the desired thickness (hereinafter referred to as thick toner) is supplied to the residual region. At the time of mounting and transfer, the thick toner transferred to the paper is peeled off from the paper, and white spots are generated in the formed image.

<Evaluation of electrical characteristics>
The electrical characteristics of the photoconductor were evaluated before (initially) and after (after printing) the above <evaluation of wear resistance> and <evaluation of suppression of slip-through of toner and the like>. The evaluation of the electrical characteristics was performed in an environment of a temperature of 10 ° C. and a relative humidity of 20% RH.

First, the electrical characteristics of the initial photoconductor were evaluated by the following method. The surface of the photoconductor was charged to −600 V using a drum sensitivity tester (manufactured by Gentec Co., Ltd.). Next, monochromatic light (wavelength 780 nm, light energy 0.26 μJ / cm ² ) was extracted from the white light of the halogen lamp using a bandpass filter. The surface of the photoconductor was irradiated with the extracted monochromatic light. The surface potential of the photoconductor was measured 50 milliseconds after the start of irradiation. The measured surface potential was defined as the post-exposure potential ( _VL1 , unit: V) of the initial photoconductor.

Next, the surface potential of the photoconductor after printing was measured by the same method as the initial measurement of the surface potential of the photoconductor. The measured surface potential was defined as the post-exposure potential ( _VL2 , unit: V) of the photoconductor after printing.

The measured post-exposure potential (V _L1 ) of the photoconductor and the post-exposure potential (V _L2 ) of the photoconductor after printing are shown in Tables 7 and 8. Further, from these post-exposure potentials, the electrical characteristics of the photoconductor were evaluated according to the following criteria.

[Evaluation criteria for electrical characteristics of initial photoconductors]
Good: The absolute value of the post-exposure potential ( _VL1 ) of the initial photoconductor is 100 V or less.
Defective: The absolute value of the post-exposure potential ( _VL1 ) of the initial photoconductor is over 100 V.

[Evaluation criteria for electrical characteristics of photoconductor after printing]
Good: The absolute value of the post-exposure potential ( _VL2 ) of the photoconductor after printing is 150 V or less.
Defective: The absolute value of the post-exposure potential ( _VL2 ) of the photoconductor after printing is over 150 V.

The terms in Tables 5 and 6 are as follows. "Resin" refers to polyarylate resin. "HTM" refers to a hole transport agent. "First HTM" refers to a first hole transport agent. "Second HTM" refers to a second hole transport agent. “W1 / W2” indicates the ratio W1 / W2 of the mass W1 of the first hole transporting agent to the mass W2 of the second hole transporting agent. The ratio W1 / W2 was calculated from the formula “ratio W1 / W2 = mass of the first hole transporting agent (unit: parts by mass) / mass of the second hole transporting agent (unit: parts by mass)”. The terms in Tables 7 and 8 are as follows. “Toner slip-through” indicates an evaluation of suppression of toner slip-through. “V _L1 (initial)” indicates the post-exposure potential (V _L1 ) of the initial photoconductor. “V _L2 (after printing)” indicates the post-exposure potential (V _L2 ) of the photoconductor after printing. “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.

The photosensitive layers (more specifically, the charge generating layer) of the laminated photoconductors (A-1) to (A-29) contained a charge generating agent. As shown in Table 5, the photosensitive layers (more specifically, the charge transporting layer) of the laminated photoconductors (A-1) to (A-29) are a first hole transporting agent and a second hole. It contained at least a transport agent and a binder resin (more specifically, any of polyarylate resins (R-1) to (R-6)). As shown in Table 4, the polyarylate resins (R-1) to (R-6) each include a repeating unit (1), a repeating unit (2), and a repeating unit (3), and are repeating units. The ratio n ₁ / n ₂ of the number n ₁ of the repeating unit (1) to the number n ₂ of (2) was 1.0 or more. As shown in Table 5, the first hole transporting agent is included in the general formulas (20), (21), (22), or (23), and the first hole transporting agent (HTM-1) to It was one of the compounds of (HTM-11). As shown in Table 5, the second hole transporting agent is one of the second hole transporting agents (HTM-12) and (HTM-13) included in the general formula (24) or (25). It was one compound. As shown in Table 5, the ratio W1 / W2 of the mass W1 of the first hole transporting agent to the mass W2 of the second hole transporting agent was 1.0 or more and 3.0 or less.

As shown in Table 7, the amount of wear of the laminated photoconductors (A-1) to (A-29) is 3.0 μm or less, and the laminated photoconductors (A-1) to (A-29) have a wear amount of 3.0 μm or less. It had excellent wear resistance. Further, the evaluation of the suppression of toner and the like of the laminated photoconductors (A-1) to (A-29) was A, and the slipping of the toner and the like at the contact portion with the cleaning blade was suppressed. Further, the absolute value of the post-exposure potential of the initial photoconductors of the laminated photoconductors (A-1) to (A-29) is 100 V or less, and the absolute value of the post-exposure potential of the photoconductor after printing is 150 V or less. Met. From this, the laminated photoconductors (A-1) to (A-29) have excellent wear resistance while maintaining electrical characteristics, and can suppress the slip-through of toner or the like at the contact portion with the cleaning blade. Shown.

From the above, it was shown that the photoconductor according to the present invention has excellent wear resistance and can suppress the slip-through of toner and the like at the contact portion with the cleaning blade.

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 at least a charge generating agent, a first hole transporting agent, a second hole transporting agent, and a binder resin.
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 first hole transporting agent is at least one compound among the compounds represented by the general formulas (20) to (23).
The second hole transporting agent is at least one compound among the compounds represented by the general formulas (24) and (25).
An electrophotographic photosensitive member in which the ratio of the mass of the first hole transporting agent to the mass of the second hole transporting agent is 1.0 or more and 3.0 or less.

(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 (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 (23), R ^{51 to} R ⁵⁵ each independently represent an alkyl group having 1 or more and 8 or less carbon atoms or an alkoxy group having 1 or more and 8 or less carbon atoms, and g1, g2, g3, and g4. , And G5 each independently represent an integer of 0 or more and 5 or less. )

(In the general formula (24), R ^{61 to} R ⁶³ independently represent an alkyl group having 1 or more and 8 or less carbon atoms or an alkoxy group having 1 or more and 8 or less carbon atoms, and R ⁶⁴ and R ⁶⁵ are , Each independently represent a hydrogen atom, an alkyl group having 1 or more and 8 or less carbon atoms, or an aryl group having 6 or more and 14 or less carbon atoms, and k1 and k2 each independently represent an integer of 0 or more and 5 or less. , K3 represents an integer of 0 or more and 4 or less.
In the general formula (25), R ^{71 to} R ⁷⁴ independently represent an alkyl group having 1 or more and 8 or less carbon atoms or an alkoxy group having 1 or more and 8 or less carbon atoms, and r1, r2, r3, and r4 independently represents an integer of 0 or more and 5 or less. ) 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.

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. Represents an integer of, f3 and f6 each represent 0,
In the general formula (23), R ^{51 to} R ⁵⁵ each independently represent an alkyl group having 1 or more and 8 or less carbon atoms, and g1, g2, g3, g4, and g5 independently represent 0 or 0 or 5, respectively. Represents 1
In the general formula (24), R ^{61 to} R ⁶³ each independently represent an alkyl group having 1 or more and 8 or less carbon atoms, and R ⁶⁴ and R ⁶⁵ each independently represent 1 or more and 8 or less carbon atoms. Represents the alkyl group of, k1 and k2 each represent 1, and k3 represents 0.
In the general formula (25), R ⁷¹ ~R ⁷⁴ each independently represent an alkyl group having 1 to 8 carbon atoms, r1, r2, r3, and r4 are each independently 0 or 1 The electrophotographic photosensitive member according to claim 1 or 2. The first hole transporting agent is at least one compound among the compounds represented by the chemical formulas (HTM-1) to (HTM-11).
The electron according to any one of claims 1 to 3, wherein the second hole transporting agent is at least one compound among the compounds represented by the chemical formulas (HTM-12) and (HTM-13). Photophotoreceptor.

The photosensitive layer includes a charge generating layer containing the charge generating agent, and a charge transporting layer containing the first hole transporting agent, the second hole transporting agent, and the binder resin. The electrophotographic photosensitive member according to any one of the items to 4. The charge transport layer further contains a third compound.
The electrophotographic photosensitive member according to claim 5, wherein the third compound has a ketone structure or a dicyanomethylene structure. The electrophotographic photosensitive member according to claim 6, wherein the third compound is at least one compound among the compounds represented by the general formulas (31) to (39).

(In the general formula (31) ~ (39), Q 31 ~Q 57 are each independently a hydrogen atom, a halogen atom, 1 or more carbon atoms of 5 or less alkyl group, a carbon atom number of 6 to 14 aryl Represents an alkoxy group having 1 or more and 3 or less carbon atoms which may be substituted with a group, or an alkyl group having 1 or more and 3 or less carbon atoms or a phenyl group which may be substituted with an alkoxy group having 1 or more and 3 or less carbon atoms. .) The electrophotographic photosensitive member according to claim 6 or 7, wherein the third compound is at least one compound among the compounds represented by the chemical formulas (E-1) to (E-11).

The electrophotographic photosensitive member according to any one of claims 5 to 8, wherein the charge transport layer is provided as one layer and as the outermost surface layer.

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