JP7415330B2 - Electrophotographic photoreceptors, process cartridges, and image forming devices - Google Patents

Description

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

An electrophotographic photoreceptor is used as an image carrier in an electrophotographic image forming apparatus (for example, a printer or a multifunctional device). The electrophotographic photoreceptor includes a photosensitive layer. As the electrophotographic photoreceptor, for example, a single layer type electrophotographic photoreceptor and a laminated type electrophotographic photoreceptor are used. A single-layer electrophotographic photoreceptor includes a single-layer photosensitive layer having a charge generation function and a charge transport function. The laminated electrophotographic photoreceptor includes a photosensitive layer including a charge generation layer having a charge generation function and a charge transport layer having a charge transport function.

Patent Document 1 describes an electrophotographic photoreceptor 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 Patent Application Publication No. 2003-322982

However, studies by the present inventors have revealed that the image forming member described in Patent Document 1 is insufficient in wear resistance.

The present invention has been made in view of the above-mentioned problems, and an object thereof is to provide an electrophotographic photoreceptor having excellent wear resistance. Another object of the present invention is to provide a process cartridge and an image forming apparatus that are equipped with such an electrophotographic photoreceptor and have excellent durability.

The electrophotographic photoreceptor of the present invention includes a conductive substrate and a photosensitive layer. The photosensitive layer is a single layer. The photosensitive layer contains a charge generating agent, a hole transporting agent, an electron transporting agent, and a polyarylate resin. The polyarylate resin includes at least 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 repeating units represented by the general formula (1) to the number n ₂ of repeating units represented by formula (1 ₎ is 1.0 or more. The electron transport agent includes a compound represented by general formula (10), (11), or (12).

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, R ¹ and R ² each represent a methyl group, and R ³ and R ⁴ combine with each other to represent a cycloalkylidene group having 5 or 6 carbon atoms.

In the general formula (10), Q ^5A and Q ^5B each independently represent 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. Q ^6A and Q ^6B each independently represent an alkyl group having 1 to 8 carbon atoms, a phenyl group, or an alkoxy group having 1 to 8 carbon atoms. m ₁ and m ₂ each independently represent an integer of 0 or more and 4 or less. In the general formula (11), Q ⁷ and Q ⁸ each independently represent 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. Q ⁹ represents an alkyl group having 1 to 8 carbon atoms, a phenyl group, or an alkoxy group having 1 to 8 carbon atoms. m ₃ represents an integer from 0 to 4. In the general formula (12), Q ¹⁰ and Q ¹¹ each independently represent an alkyl group having 1 to 6 carbon atoms or a hydrogen atom. Q ¹² represents a halogen atom or a hydrogen atom.

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

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

The electrophotographic photoreceptor of the present invention has excellent wear resistance. Further, the process cartridge and image forming apparatus of the present invention have excellent durability because they include an electrophotographic photoreceptor having excellent wear resistance.

1 is a partial cross-sectional view of an electrophotographic photoreceptor according to an embodiment of the present invention. 1 is a partial cross-sectional view of an electrophotographic photoreceptor according to an embodiment of the present invention. 1 is a partial cross-sectional view of an electrophotographic photoreceptor according to an embodiment of the present invention. FIG. 1 is a cross-sectional view showing an example of an image forming apparatus.

Embodiments of the present invention will be described in detail below. However, the present invention is not limited to the following embodiments. The present invention can be implemented with appropriate modifications within the scope of the purpose of the present invention. Note that the description may be omitted as appropriate for parts where the description overlaps, but the gist of the invention is not limited. Hereinafter, the compound and its derivatives may be collectively referred to by adding "system" after the compound name. Furthermore, when a polymer name is expressed 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 this specification will be explained. 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 (iodo group).

An alkyl group having 1 to 8 carbon atoms, an alkyl group having 1 to 6 carbon atoms, an alkyl group having 1 to 3 carbon atoms, an alkyl group having 2 carbon atoms, and an alkyl group having 3 carbon atoms. , each is linear or branched and unsubstituted unless otherwise specified. Examples of the alkyl group having 1 to 8 carbon atoms include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, sec-butyl group, tert-butyl group, n-pentyl group, 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 -trimethylpropyl, 1-ethylbutyl, 2-ethylbutyl and 3-ethylbutyl groups, straight-chain and branched heptyl groups, and straight-chain and branched octyl groups. Examples of an alkyl group having 1 to 6 carbon atoms, an alkyl group having 1 to 3 carbon atoms, an alkyl group having 2 carbon atoms, and an alkyl group having 3 carbon atoms each have 1 to 8 carbon atoms. Among the groups mentioned as examples of the alkyl group below, it is a group having the corresponding number of carbon atoms.

An alkoxy group having 1 to 8 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, and an alkoxy group having 1 to 3 carbon atoms are each linear or branched unless otherwise specified. It is non-replaceable. Examples of the alkoxy group having 1 to 8 carbon atoms include methoxy group, ethoxy group, n-propoxy group, isopropoxy group, n-butoxy group, sec-butoxy group, tert-butoxy group, 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- Trimethylpropoxy group, 1,2,2-trimethylpropoxy group, 1-ethylbutoxy group, 2-ethylbutoxy group, 3-ethylbutoxy group, linear and branched heptyloxy group, and linear and A branched octyloxy group is mentioned. Examples of an alkoxy group having 1 to 6 carbon atoms and an alkoxy group having 1 to 3 carbon atoms are the corresponding carbon atoms among the groups described as examples of alkoxy groups having 1 to 8 carbon atoms, respectively. It is a group having a number of atoms. The substituents used in this specification have been explained above.

<Electrophotographic photoreceptor>
The present embodiment relates to an electrophotographic photoreceptor (hereinafter sometimes referred to as a photoreceptor). The photoreceptor 1 of this embodiment will be described below with reference to FIGS. 1 to 3. 1 to 3 each show a partial cross-sectional view of the photoreceptor 1. FIG.

As shown in FIG. 1, the photoreceptor 1 includes, for example, a conductive base 2 and a photosensitive layer 3. The photosensitive layer 3 is a single layer. The photoreceptor 1 is a single-layer electrophotographic photoreceptor including a single-layer photoreceptor layer 3 .

As shown in FIG. 2, the photoreceptor 1 may include a conductive substrate 2, a photosensitive layer 3, and an intermediate layer 4 (undercoat layer). Intermediate layer 4 is provided between conductive substrate 2 and photosensitive layer 3. As shown in FIG. 1, the photosensitive layer 3 may be provided directly on the conductive substrate 2. Alternatively, as shown in FIG. 2, the photosensitive layer 3 may be provided on the conductive substrate 2 with an intermediate layer 4 interposed therebetween.

As shown in FIG. 3, the photoreceptor 1 may include a conductive substrate 2, a photosensitive layer 3, and a protective layer 5. A protective layer 5 is provided on the photosensitive layer 3. As shown in FIGS. 1 and 2, the photosensitive layer 3 is preferably provided as the outermost layer of the photoreceptor 1. By providing the photosensitive layer 3 containing a polyarylate resin (PA) described later and a specific electron transport agent described later as the outermost layer, the wear resistance of the photoreceptor 1 can be easily improved. Note that, as shown in FIG. 3, the protective layer 5 may be provided as the outermost layer of the photoreceptor 1.

The photosensitive layer 3 contains at least a charge generating agent, a hole transporting agent, an electron transporting agent, and a polyarylate resin.

The thickness of the photosensitive layer 3 is not particularly limited, but is preferably 5 μm or more and 100 μm or less, more preferably 10 μm or more and 50 μm or less. The photoreceptor 1 has been described above with reference to FIGS. 1 to 3.

(charge generating agent)
Examples of the charge generating agent include phthalocyanine pigments, perylene pigments, bisazo pigments, trisazo pigments, dithioketopyrrolopyrrole pigments, metal-free naphthalocyanine pigments, metal naphthalocyanine pigments, squaraine pigments, indigo pigments, azulenium pigments, and cyanine. Pigments, powders of inorganic photoconductive materials (e.g. selenium, selenium-tellurium, selenium-arsenic, cadmium sulfide, and amorphous silicon), pyrylium pigments, anthanthrone pigments, triphenylmethane pigments, threnic pigments, toluidine pigments , pyrazoline pigments, and quinacridone pigments. The photosensitive layer may contain only one kind of charge generating agent, or may contain two or more kinds of charge generating agents.

A phthalocyanine pigment is a pigment having a phthalocyanine structure. Examples of the phthalocyanine pigment include metal-free phthalocyanine and metal phthalocyanine. Examples of the metal phthalocyanine include titanyl phthalocyanine, hydroxygallium phthalocyanine, and chlorogallium phthalocyanine. Metal-free phthalocyanine is 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 metal-free phthalocyanine crystals include X-type crystals of metal-free phthalocyanine (hereinafter sometimes referred to as X-type metal-free phthalocyanine). Examples of titanyl phthalocyanine crystals 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, in a digital optical image forming apparatus (for example, a laser beam printer or facsimile using a light source such as a semiconductor laser), it is preferable to use a photoreceptor having sensitivity in a wavelength region of 700 nm or more. Since it has a high quantum yield in a wavelength region of 700 nm or more, the charge generating agent is preferably a phthalocyanine pigment, more preferably a metal-free phthalocyanine or titanyl phthalocyanine, further preferably titanyl phthalocyanine, and particularly preferably Y-type titanyl phthalocyanine. .

Y-type titanyl phthalocyanine has a main peak at, for example, a Bragg angle (2θ±0.2°) of 27.2° in the CuKα characteristic X-ray diffraction spectrum. 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, for example, by the following method. First, a sample (titanyl phthalocyanine) is filled into a sample holder of an X-ray diffraction device (for example, "RINT (registered trademark) 1100" manufactured by Rigaku Co., Ltd.). In addition, the X-ray diffraction spectrum is measured under the conditions that the CuKα characteristic X-ray wavelength is 1.542 Å. The measurement range (2θ) is, for example, 3° or more and 40° or less (start angle of 3°, stop angle of 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.

The content of the charge generating agent is preferably 0.1 parts by mass or more and 50 parts by mass or less, more preferably 0.5 parts by mass or more and 4.5 parts by mass or less, based on 100 parts by mass of the binder resin. preferable.

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

In 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 general formula (1), R ¹ and R ² each represent a methyl group, and R ³ and R ⁴ combine with each other to represent a cycloalkylidene group having 5 or 6 carbon atoms.

Hereinafter, the repeating unit represented by general formula (1), the repeating unit represented by chemical formula (2), and the repeating unit represented by chemical formula (3) will be referred to as repeating unit (1), repeating unit (2), respectively. ), and repeating unit (3). Further, it includes at least a repeating unit (1), a repeating unit (2), and a repeating unit (3), and the ratio of the number n ₁ of repeating units (1) to the number n ₂ of repeating units (2) is n ₁ /n ₂ A polyarylate resin having 1.0 or more is sometimes referred to as a polyarylate resin (PA).

Polyarylate resin (PA), when contained in the photosensitive layer, can improve the abrasion resistance of the photoreceptor. The reason is assumed to be as follows.

First, the polyarylate resin (PA) contains repeating units (2) and repeating units (3). Thereby, the wear resistance of the photoreceptor 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. Furthermore, the ratio n ₁ /n ₂ of the number n ₁ of repeating units (1) to the number n _{2 of} repeating units (2) is 1.0 or more, so that the polyarylate resin (PA ) can be further improved. By improving the solubility of polyarylate resin (PA), a photosensitive layer can be suitably formed, and the abrasion resistance of the photoreceptor can be improved.

In addition to repeating units (1), (2), and (3), polyarylate resin (PA) contains a repeating unit represented by chemical formula (4) (hereinafter sometimes referred to as repeating unit (4)). It is preferable to further include. When the polyarylate resin (PA) contains the repeating unit (4), the abrasion resistance of the photoreceptor can be further improved.

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

Examples of the cycloalkylidene group having 5 or 6 carbon atoms in which R ³ and R ⁴ in the general formula (1) are bonded to each other include a cyclopentylidene group and a cyclohexylidene group. A cyclopentylidene group and a 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 preferred.

Suitable examples of the repeating unit (1) include repeating units represented by chemical formulas (1-1), (1-2), (1-3), (1-4), and (1-5). Can be mentioned. Hereinafter, the repeating units represented by chemical formulas (1-1), (1-2), (1-3), (1-4), and (1-5) are respectively referred to as repeating units (1-1). , (1-2), (1-3), (1-4), and (1-5).

In order to improve the abrasion resistance of the photoreceptor, the polyarylate resin (PA) further contains a repeating unit (4) in addition to the repeating units (1), (2), and (3), and the repeating unit ( It is preferable that 1) is a repeating unit (1-1).

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

The ratio n ₁ /n 2 of the number n ₁ of repeating units (1) contained in the polyarylate resin (PA) to the number n ₂ of repeating units ( ₂ ) contained in the polyarylate resin (PA) is 1.0. That's all. That is, the number n ₁ of repeating units (1) is equal to or greater than the number n ₂ of repeating units ( 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 abrasion resistance of the photoreceptor can be improved. . In order to improve the abrasion resistance of the photoreceptor, the ratio n ₁ /n ₂ is preferably 10.0 or less, more preferably 5.0 or less. In order to improve the abrasion resistance of the photoreceptor while improving the solubility of the polyarylate resin (PA) in the solvent for forming the photoreceptor layer, the ratio n ₁ /n ₂ is 1.0, 2.0, It is also preferred that it is within a 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.

When the polyarylate resin (PA) contains repeating units (4), the repeating units (4) contained in the polyarylate resin (PA) relative to the number n ₃ of repeating units (3) contained in the polyarylate resin (PA) The ratio n ₄ /n ₃ of the number n ₄ is preferably larger than 0.0, more preferably 0.1 or more, and even more preferably 0.5 or more. The ratio n ₄ /n ₃ is preferably 5.0 or less, more preferably 3.0 or less, and even more preferably 1.5 or less. It is also preferred that the ratio n ₁ /n ₂ is within a range of two values selected from 0.1, 0.5, 1.0, 1.5, 3.0 and 5.0. The ratio n ₄ /n ₃ may be, for example, 1.0.

The ratio n ₁ /n ₂ can be adjusted by changing the amount of compound (BP-1) and compound (BP-2) added when producing polyarylate resin (PA). . In addition, the ratio n ₄ /n ₃ can be adjusted by changing the amount of compound (DC-3) and the amount of compound (DC-4) added when producing polyarylate resin (PA). I can do it. Note that Compound (BP-1), Compound (BP-2), Compound (DC-3), and Compound (DC-4) will be described later.

The ratio n ₁ /n ₂ and the ratio n ₄ /n ₃ are each an average value of values obtained from the entire polyarylate resin (PA) (a plurality of molecular chains) contained in the photosensitive layer. The ratio n ₁ /n ₂ and the ratio n ₄ /n ₃ are the ¹ H-NMR spectra obtained by measuring the ¹ H-NMR spectrum of polyarylate resin (PA) using a proton nuclear magnetic resonance spectrometer. It can be obtained by calculating the ratio of peaks characteristic of each repeating unit in .

Specific examples of polyarylate resins (PA) include the following polyarylate resins.
Polyarylate resin (polyarylate resin) containing repeating units (1-1), (2) and (3), but not containing repeating unit (4), and having a ratio n ₁ /n ₂ of 2.0 or more and 5.0 or less (sometimes referred to as resin (I));
Polyarylate resin containing 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 (can be described as polyarylate resin (II)) be);
Polyarylate resin containing repeating units (1-1), (2), (3) and (4) and having a ratio n ₁ /n ₂ of 2.0 or more and 5.0 or less (polyarylate resin (III)) );
Polyarylate resin containing 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 (can be described as polyarylate resin (IV)) be);
Polyarylate resin containing 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 (can be described as polyarylate resin (V)) be);
Polyarylate resin containing 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 (can be described as polyarylate resin (VI)) and a polyarylate containing repeating units (1-1), (2) and (3), but not containing repeating unit (4), and having a ratio n ₁ /n ₂ of 1.0 or more and less than 2.0. resin (sometimes described as polyarylate resin (VII)).

More specific examples of polyarylate resins (PA) include the following polyarylate resins.
Polyarylate resin (polyarylate resin (i)) containing only repeating units (1-1), (2) and (3) as repeating units and having a ratio n ₁ /n ₂ of 2.0 or more and 5.0 or less );
Polyarylate resin (polyarylate resin (ii)) containing only repeating units (1-5), (2) and (3) as repeating units and having a ratio n ₁ /n ₂ of 2.0 or more and 5.0 or less );
_Polyarylate resin ( _polyarylate (sometimes described as resin (iii));
Polyarylate resin (polyarylate resin (iv)) containing only repeating units (1-2), (2) and (3) as repeating units and having a ratio n ₁ /n ₂ of 2.0 or more and 5.0 or less );
Polyarylate resin (polyarylate resin (v)) containing only repeating units (1-3), (2) and (3) as repeating units and having a ratio n ₁ /n ₂ of 2.0 or more and 5.0 or less );
Polyarylate resin (polyarylate resin (vi)) containing only repeating units (1-4), (2) and (3) as repeating units and having a ratio n ₁ /n ₂ of 2.0 or more and 5.0 or less ); and a polyester containing only repeating units (1-1), (2) and (3) as repeating units and having a ratio n ₁ /n ₂ of 1.0 or more and less than 2.0. Arylate resin (sometimes referred to as polyarylate resin (vii)).

More specific examples of polyarylate resins (PA) include polyarylate resins represented by chemical formulas (R-1) to (R-7) (hereinafter referred to as polyarylate resins (R-1) to (R-7), respectively). -7)). In addition, in chemical formulas (R-1) to (R-7), the number attached to the lower right of each repeating unit represents the percentage (%) of the number of each repeating unit 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. Furthermore, for convenience of description, two repeating units (3) are shown in each of chemical formulas (R-1), (R-2), and (R-4) to (R-7). However, the percentage of the number of repeating units (3) to the total number of repeating units contained in each of polyarylate resins (R-1), (R-2), and (R-4) to (R-7) is 50.0% (the sum of the numbers attached to the lower right of the two repeating units (3)).

In order to improve the abrasion resistance of the photoreceptor, the repeating unit (1) is preferably a repeating unit (1-5). The polyarylate resin (PA) in which the repeating unit (1) is the repeating unit (1-5) is preferably a polyarylate resin (II), more preferably a polyarylate resin (ii), and a polyarylate resin (R-2). ) is more preferred.

In order to improve the abrasion resistance of the photoreceptor, repeating unit (1-1) is also preferred as repeating unit (1). As the polyarylate resin (PA) in which the repeating unit (1) is the repeating unit (1-1), polyarylate resins (I) and (III) are preferable, and polyarylate resins (i) and (iii) are more preferable. , polyarylate resins (R-1) and (R-3) are more preferred.

In order to further improve the abrasion resistance of the photoreceptor, it is preferable that the repeating unit (1) is the repeating unit (1-1) and the repeating unit (4) is further included. As the polyarylate resin (PA) in which the repeating unit (1) is the repeating unit (1-1) and further contains the repeating unit (4), polyarylate resin (III) is preferable, and polyarylate resin (iii) is more preferable. , polyarylate resin (R-3) is more preferred.

In polyarylate resin (PA), repeating units derived from bisphenol and repeating units derived from dicarboxylic acid are adjacent to each other and bonded to each other. The number of bisphenol-derived repeating units contained in the polyarylate resin (PA) is equal to the number of dicarboxylic acid-derived repeating units. Bisphenol-derived repeating units are, for example, repeating units (1) and (2). Further, the dicarboxylic acid-derived repeating unit is, for example, the repeating unit (3). When the polyarylate resin (PA) contains repeating units (4), the dicarboxylic acid-derived repeating units are, for example, repeating units (3) and (4).

The polyarylate resin (PA) may be, for example, a random copolymer, an alternating copolymer, a periodic copolymer or a block copolymer. In the polyarylate resin (PA), the arrangement of the repeating units is not particularly limited as long as the repeating units derived from bisphenol and the repeating units derived from dicarboxylic acid are adjacent to each other and bonded to each other. For example, the repeating unit (1) may be bonded to both ends of the repeating unit (3). Alternatively, the repeating unit (2) may be bonded to both ends of the repeating unit (3). Alternatively, the repeating unit (1) may be bonded to one end of the repeating unit (3), and the repeating unit (2) may be bonded to the other end of the repeating unit (3).

When the polyarylate resin (PA) does not contain the repeating unit (4), the polyarylate resin (PA) may contain only the repeating units (1), (2), and (3) as repeating units. When the polyarylate resin (PA) does not contain the repeating unit (4), the polyarylate resin (PA) contains the repeating unit (1) in addition to the repeating units (1), (2), and (3) as repeating units. ), (2), (3) and (4) may further contain repeating units other than those in (4).

When the polyarylate resin (PA) contains repeating units (4), the polyarylate resin (PA) contains only repeating units (1), (2), (3) and (4) as repeating units. Good too. When the polyarylate resin (PA) contains repeating units (4), the polyarylate resin (PA) contains repeating units (1), (2), (3), and (4) as repeating units. It may further contain repeating units other than units (1), (2), (3) and (4).

The viscosity average molecular weight of the polyarylate resin (PA) is preferably 10,000 or more, more preferably 20,000 or more, even more preferably 30,000 or more, and 40,000 or more. It is particularly preferable. When the viscosity average molecular weight of the polyarylate resin (PA) is 10,000 or more, the abrasion resistance of the photoreceptor can be improved. On the other hand, the viscosity average molecular weight of the polyarylate resin (PA) is preferably 80,000 or less, 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 polyarylate resin (PA) is not particularly limited. Examples of the method for producing polyarylate resin (PA) include a method in which bisphenol for forming bisphenol-derived repeating units and dicarboxylic acid for forming dicarboxylic acid-derived repeating units are subjected to condensation polymerization. In order to carry out condensation polymerization, a known synthesis method (for example, solution polymerization, melt polymerization, or interfacial polymerization) can be employed.

Examples of bisphenols for constituting bisphenol-derived repeating units include compounds represented by general formula (BP-1) (hereinafter sometimes referred to as compound (BP-1)), and chemical formula (BP-2). ) (hereinafter sometimes referred to as compound (BP-2)). Examples of the dicarboxylic acid for constituting the dicarboxylic acid-derived repeating unit include a compound represented by the chemical formula (DC-3) (hereinafter sometimes referred to as compound (DC-3)). When the polyarylate resin (PA) contains the repeating unit (4), in addition to the compound (DC-3), a compound represented by the chemical formula (DC-4) (hereinafter referred to as compound (DC-4)) is used as the dicarboxylic acid. 4)) is further added. R ¹ , R ² , R ³ and R ⁴ in general formula (BP-1) have the same meanings as R ¹ , R ² , R ³ and R ⁴ in general formula (1), respectively.

Suitable examples of compound (BP-1) include compounds represented by chemical formulas (BP-1-1) to (BP-1-5) (hereinafter referred to as compounds (BP-1-1) to (BP-1-5), respectively). -1-5)).

Bisphenols (eg, compound (BP-1) and compound (BP-2)) may be used after being derivatized into aromatic diacetate. Dicarboxylic acids (eg, compound (DC-3) and compound (DC-4)) may be used after being derivatized. Examples of dicarboxylic acid derivatives include dicarboxylic acid dichloride, dicarboxylic acid dimethyl ester, dicarboxylic acid diethyl ester, and dicarboxylic acid anhydride. Dicarboxylic acid dichloride is a compound in which two "-C(=O)-OH" groups of a dicarboxylic acid are each substituted with a "-C(=O)-Cl" group.

In the condensation polymerization of bisphenol and dicarboxylic acid, one or both of a base and a 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 polyarylate resin (PA) has been described above.

The photosensitive layer may contain only one type of polyarylate resin (PA), or may contain two or more types of polyarylate resin (PA). The photosensitive layer may contain only polyarylate resin (PA) as a binder resin. Moreover, the photosensitive layer may further contain a binder resin other than polyarylate resin (PA) (hereinafter sometimes referred to as other binder resin) as a binder resin.

Other binder resins include, for example, thermoplastic resins (more specifically, polycarbonate resins, styrene resins, styrene-butadiene copolymers, styrene-acrylonitrile copolymers, styrene-maleic acid copolymers, 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 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 resins and urethane-acrylic acid copolymers). Can be mentioned.

(electron transport agent)
The photosensitive layer contains a compound represented by the general formula (10), (11), or (12) (hereinafter referred to as compound (10), (11), or (12), respectively) as an electron transport agent. ). When the photosensitive layer contains the compound (10), (11), or (12) together with the polyarylate resin (PA), the abrasion resistance of the photoreceptor can be improved.

In general formula (10), Q ^5A and Q ^5B each independently represent 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. Q ^6A and Q ^6B each independently represent an alkyl group having 1 to 8 carbon atoms, a phenyl group, or an alkoxy group having 1 to 8 carbon atoms. m ₁ and m ₂ each independently represent an integer of 0 or more and 4 or less.

When m ₁ represents an integer of 2 or more and 4 or less, the plurality of Q ^6A may be the same or different. When m ₂ represents an integer of 2 or more and 4 or less, the plurality of Q ^6Bs may be the same or different.

In general formula (10), Q ^5A and Q ^5B each independently preferably represent an alkyl group having 1 to 8 carbon atoms, more preferably an alkyl group having 1 to 6 carbon atoms. , 1,1-dimethylpropyl group. It is preferable that m ₁ and m ₂ represent 0.

In general formula (11), Q ⁷ and Q ⁸ each independently represent 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. Q ⁹ represents an alkyl group having 1 to 8 carbon atoms, a phenyl group, or an alkoxy group having 1 to 8 carbon atoms. m ₃ represents an integer from 0 to 4.

When m ₃ represents an integer of 2 or more and 4 or less, the plurality of Q ⁹ may be the same or different.

In general formula (11), Q ⁷ and Q ⁸ each independently preferably represent an alkyl group having 1 to 8 carbon atoms, more preferably an alkyl group having 1 to 6 carbon atoms. , more preferably represents a tert-butyl group. Preferably, m ₃ represents 0.

In general formula (12), Q ¹⁰ and Q ¹¹ each independently represent an alkyl group having 1 to 6 carbon atoms or a hydrogen atom. Q ¹² represents a halogen atom or a hydrogen atom.

In general formula (12), Q ¹⁰ and Q ¹¹ each independently preferably represent an alkyl group having 1 or more and 6 or less carbon atoms, and more preferably represent a tert-butyl group. Q ¹² preferably represents a halogen atom, more preferably a chlorine atom.

In order to improve the abrasion resistance of the photoreceptor, the compound (10) is preferably a compound represented by the chemical formula (10-E1) (hereinafter sometimes referred to as compound (10-E1)). For the same reason, as compound (11), a compound represented by chemical formula (11-E3) (hereinafter sometimes referred to as compound (11-E3)) is preferable. For the same reason, as compound (12), a compound represented by chemical formula (12-E2) (hereinafter sometimes referred to as compound (12-E2)) is preferable.

The content of the electron transport agent is preferably 5 parts by mass or more and 150 parts by mass or less, more preferably 10 parts by mass or more and 50 parts by mass or less, and 20 parts by mass or more, based on 100 parts by mass of the binder resin. More preferably, it is 40 parts by mass or less.

The photosensitive layer may contain only one type of electron transport agent, or may contain two or more types of electron transport agents. The photosensitive layer may further contain an electron transport agent other than compounds (10), (11), and (12) (hereinafter sometimes referred to as other electron transport agent). Examples of other electron transport agents include quinone compounds, diimide compounds, hydrazone compounds, malononitrile compounds, thiopyran compounds, trinitrothioxanthone compounds, and 3,4,5,7-tetranitro-9-fluorenone compounds. Examples include dinitroanthracene compounds, dinitroacridine compounds, tetracyanoethylene, 2,4,8-trinitrothioxanthone, dinitrobenzene, dinitroacridine, succinic anhydride, maleic anhydride, and dibromomaleic anhydride. Examples of quinone compounds include diphenoquinone compounds, azoquinone compounds, anthraquinone compounds, naphthoquinone compounds, nitroanthraquinone compounds, and dinitroanthraquinone compounds.

(hole transport agent)
Examples of hole transport agents include triphenylamine derivatives, diamine derivatives (for example, N,N,N',N'-tetraphenylbenzidine derivatives, N,N,N',N'-tetraphenylphenylenediamine derivatives, N,N,N',N'-tetraphenylnaphthylenediamine derivative, N,N,N',N'-tetraphenylphenantolylenediamine derivative, and di(aminophenylethenyl)benzene derivative), oxadiazole type compounds (e.g. 2,5-di(4-methylaminophenyl)-1,3,4-oxadiazole), styryl type compounds (e.g. 9-(4-diethylaminostyryl)anthracene), carbazole type compounds (e.g. 9-(4-diethylaminostyryl)anthracene), For example, polyvinylcarbazole), organic polysilane compounds, pyrazoline compounds (for example, 1-phenyl-3-(p-dimethylaminophenyl)pyrazoline), hydrazone compounds, indole compounds, oxazole compounds, isoxazole compounds, thiazole Examples include thiadiazole-based compounds, thiadiazole-based compounds, imidazole-based compounds, pyrazole-based compounds, and triazole-based compounds. The photosensitive layer may contain only one type of hole transport agent, or may contain two or more types of hole transport agents.

Suitable examples of hole transport agents include compounds represented by general formulas (20), (21), (22), (23), (24), and (25) (hereinafter, each will be referred to as a compound ( 20), (21), (22), (23), (24), and (25)). The photosensitive layer contains a polyarylate resin (PA), a compound (10), (11), or (12) as an electron transport agent, and a compound (20), (21), (22) as a hole transport agent. By containing (23), (24), or (25), the abrasion resistance of the photoreceptor can be improved without impairing the sensitivity characteristics of the photoreceptor.

In general formula (20), R ¹⁰ , R ¹¹ , R ¹² , R ¹³ and R ¹⁴ each independently represent an alkyl group having 1 to 6 carbon atoms or a hydrogen atom. a and b each independently represent 0 or 1.

In general formula (20), R ¹⁰ , R ¹¹ , R ¹² , R ¹³ , and R ¹⁴ each independently preferably represent an alkyl group having 1 to 6 carbon atoms, and preferably 1 to 3 carbon atoms. It is more preferable to represent the following alkyl group, and still more preferably to represent a methyl group.

In general formula (21), R ¹⁵ , R ¹⁶ , and R ¹⁷ each independently represent an alkyl group having 1 to 6 carbon atoms. R ¹⁸ represents an alkyl group having 1 to 6 carbon atoms or a hydrogen atom. r, s, and t each independently represent an integer of 0 or more and 5 or less.

In general formula (21), when r represents an integer of 2 or more and 5 or less, a plurality of R ^15s may be the same or different. When s represents an integer of 2 or more and 5 or less, a plurality of R ¹⁶ 's may be the same or different. When t represents an integer of 2 or more and 5 or less, a plurality of R ^17s may be the same or different.

In general formula (21), R ¹⁸ preferably represents a hydrogen atom. Preferably, r, s, and t each represent 0.

In general formula (22), R ¹⁹ , R ²⁰ , R ²¹ , and R ²² each independently represent an alkyl group having 1 to 6 carbon atoms. u, v, w, and x each independently represent an integer of 0 or more and 5 or less.

In general formula (22), when u represents an integer of 2 or more and 5 or less, a plurality of R ^19s may be the same or different. When v represents an integer of 2 or more and 5 or less, a plurality of R ²⁰ 's may be the same or different. When w represents an integer of 2 or more and 5 or less, a plurality of R ²¹ 's may be the same or different. When x represents an integer of 2 or more and 5 or less, the plurality of R ^22s may be the same or different.

In general formula (22), R ¹⁹ , R ²⁰ , R ²¹ , and R ²² each independently preferably represent an alkyl group having 1 to 3 carbon atoms, and preferably represent a methyl group or an ethyl group. More preferred. It is preferable that u, v, w, and x each independently represent an integer of 1 or more and 3 or less, and more preferably 1.

In general formula (23), R ²³ and R ²⁴ 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. R ²⁵ and R ²⁶ each independently represent an alkyl group having 1 to 8 carbon atoms, an alkoxy group having 1 to 8 carbon atoms, or a phenyl group. R ²⁷ , R ²⁸ , R ²⁹ , R ³⁰ , and R ³¹ each independently represent a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, an alkoxy group having 1 to 8 carbon atoms, or a phenyl group. represent. Adjacent two of R ²⁷ , R ²⁸ , R ²⁹ , R ³⁰ and R ³¹ may be bonded to each other to represent a ring. d and e each independently represent an integer of 0 or more and 5 or less. f and g each independently represent 1 or 2.

In general formula (23), when d represents an integer of 2 or more and 5 or less, a plurality of R ^25s may be the same or different. When e represents an integer of 2 or more and 5 or less, a plurality of ^R26s may be the same or different. When two adjacent of R ²⁷ , R ²⁸ , R ²⁹ , R ³⁰ , and R ³¹ are bonded to each other to form a ring, this ring and R ²⁷ , R ²⁸ , R ²⁹ , R ³⁰ , and The phenyl group to which R ³¹ is bonded is condensed to form a bicyclic condensed ring group. In this case, the condensation site between the ring and the phenyl group may include a double bond.

In general formula (23), R ²³ and R ²⁴ preferably each represent a hydrogen atom. R ²⁷ , R ²⁸ , R ²⁹ , R ³⁰ and R ³¹ 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 having 1 to 8 carbon atoms represented by R ²⁷ , R ²⁸ , R ²⁹ , R ³⁰ , and R ³¹ is preferably an alkyl group having 1 to 6 carbon atoms, such as a methyl group, an ethyl group, or Preferably it represents an n-butyl group. The alkoxy group having 1 to 8 carbon atoms represented by R ²⁷ , R ²⁸ , R ²⁹ , R ³⁰ , and R ³¹ is preferably an alkoxy group having 1 to 6 carbon atoms, and preferably 1 to 3 carbon atoms. An alkoxy group is more preferred, and an ethoxy group is even more preferred. Preferably, d and e each represent 0.

In general formula (24), R ³² and R ³³ each independently represent a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, or a phenyl group. R ³⁴ , R ³⁵ , R ⁴⁶ and R ⁴⁷ each independently represent an alkyl group having 1 to 8 carbon atoms or a phenyl group. R ³⁶ to R ⁴⁵ each independently represent a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, or a phenyl group. p and q each independently represent 0 or 1. h and i each independently represent an integer of 0 or more and 5 or less. j and k each independently represent an integer from 0 to 4.

In general formula (24), when h represents an integer of 2 or more and 5 or less, a plurality of R ^34s may be the same or different. When i represents an integer of 2 or more and 5 or less, a plurality of R ^35s may be the same or different. When j represents an integer of 2 or more and 4 or less, a plurality of R ^46s may be the same or different. When k represents an integer of 2 or more and 4 or less, a plurality of R ^47s may be the same or different.

In general formula (24), R ³² and R ³³ each preferably represent a hydrogen atom. It is preferable that R ³⁶ to R ⁴⁵ each independently represent a hydrogen atom or an alkyl group having 1 or more and 8 or less carbon atoms. The alkyl group having 1 to 8 carbon atoms represented by R ³⁶ to R ⁴⁵ is preferably an alkyl group having 1 to 6 carbon atoms, more preferably an alkyl group having 1 to 3 carbon atoms, and a methyl group or Ethyl group is more preferred. Preferably, p and q each represent 0. Preferably, h and i each represent 0. Preferably, j and k each represent 0.

In general formula (25), R ⁴⁸ , R ⁴⁹ , and R ⁵⁰ each independently represent an alkyl group having 1 to 8 carbon atoms. R ⁵¹ , R ⁵² and R ⁵³ each independently represent a hydrogen atom or an alkyl group having 1 or more and 8 or less carbon atoms.

In general formula (25), R ⁴⁸ , R ⁴⁹ , and R ⁵⁰ each independently preferably represent an alkyl group having 1 to 6 carbon atoms, and represent an alkyl group having 1 to 3 carbon atoms. More preferably, it represents a methyl group. R ⁴⁸ , R ⁴⁹ , and R ⁵⁰ are preferably bonded to the meta-position of the phenyl group relative to the butadienyl group. It is preferable that R ⁵¹ , R ⁵² and R ⁵³ each represent a hydrogen atom.

More preferable examples of hole transport agents include chemical formulas (20-H8), (20-H9), (21-H4), (22-H6), (23-H1), (23-H2), ( Compounds represented by (23-H3), (24-H7), and (25-H5) (hereinafter referred to as compounds (20-H8), (20-H9), (21-H4), (22- H6), (23-H1), (23-H2), (23-H3), (24-H7), and (25-H5)).

Note that compounds (20-H8) and (20-H9) are each suitable examples of compound (20). Compound (21-H4) is a preferred example of compound (21). Compound (22-H6) is a preferred example of compound (22). Compounds (23-H1), (23-H2), and (23-H3) are each suitable examples of compound (23). Compound (24-H7) is a preferred example of compound (24). Compound (25-H5) is a preferred example of compound (25).

The content of the hole transport agent is preferably 10 parts by mass or more and 200 parts by mass or less, more preferably 50 parts by mass or more and 90 parts by mass or less, and 60 parts by mass based on 100 parts by mass of the binder resin. More preferably, the amount is 80 parts by mass or less.

(Additive)
Examples of additives include ultraviolet absorbers, antioxidants, radical scavengers, singlet quenchers, softeners, surface modifiers, extenders, thickeners, dispersion stabilizers, waxes, donors, and surfactants. agents, plasticizers, sensitizers, electron acceptor compounds, and leveling agents.

(Combination of materials)
In order to improve the abrasion resistance of the photoreceptor, combinations of polyarylate resin and electron transport agent are used as combination No. 1 shown in Table 1. Each of C-1 to C-27 is preferred. For the same reason, the combination of polyarylate resin and electron transport agent is the combination No. 1 shown in Table 1. Each of C-1 to C-27, and the charge generating agent is preferably Y-type titanyl phthalocyanine.

In order to improve the abrasion resistance of the photoreceptor, combinations of polyarylate resin, hole transport agent, and electron transport agent are used as shown in combination No. 2 shown in Table 2. Each of D-1 to D-51 is preferable. For the same reason, the combination of polyarylate resin, hole transport agent, and electron transport agent is the combination No. 2 shown in Table 2. D-1 to D-51, and it is more preferable that the charge generating agent is Y-type titanyl phthalocyanine.

In Tables 1 and 2 above, "No." indicates "combination number," "HTM" indicates "hole transport material," "ETM" indicates "electron transport material," and "resin." indicates "polyarylate resin".

(Conductive substrate)
The conductive substrate is not particularly limited as long as it can be used as a conductive substrate of a photoreceptor. The conductive substrate only needs to be made of a material that has conductivity at least on its surface. An example of the conductive substrate is a conductive substrate made of a material having conductivity. Another example of a conductive substrate is a conductive substrate coated with a material having conductivity. Examples of conductive materials include aluminum, iron, copper, tin, platinum, silver, vanadium, molybdenum, chromium, cadmium, titanium, nickel, palladium, indium, stainless steel, and brass. These electrically conductive materials may be used alone or in combination of two or more (for example, as an alloy). Among these electrically conductive materials, aluminum and aluminum alloys are preferred because they allow good charge transfer from the photosensitive layer to the electrically conductive substrate.

The shape of the conductive substrate is appropriately selected depending on the structure of the image forming apparatus. Examples of the shape of the conductive substrate include a sheet shape and a drum shape. Further, the thickness of the conductive substrate is appropriately selected depending on the shape of the conductive substrate.

(middle class)
The intermediate layer (undercoat layer) contains, for example, inorganic particles and a resin used for the intermediate layer (intermediate layer resin). The presence of the intermediate layer makes it possible to maintain an insulating state sufficient to suppress the occurrence of leakage, while smoothing the flow of current generated when the photoreceptor is exposed to light, thereby suppressing an increase in resistance.

Inorganic particles include, for example, particles of metals (e.g., aluminum, iron, and copper), particles of metal oxides (e.g., titanium oxide, alumina, zirconium oxide, tin oxide, and zinc oxide), and non-metal oxides. (eg, silica) particles. These inorganic particles may be used alone or in combination of two or more.

Examples of the intermediate layer resin are the same as the other binder resins described above. In order to form the intermediate layer and the photosensitive layer well, the resin for the intermediate layer is preferably different from the binder resin contained in the photosensitive layer. The intermediate layer may contain additives. Examples of additives contained in the intermediate layer are the same as those contained in the photosensitive layer.

(Method for manufacturing photoreceptor)
Next, an example of a method for manufacturing a photoreceptor will be described. The method for manufacturing a photoreceptor includes a photosensitive layer forming step. In the photosensitive layer forming step, a coating liquid for forming a photosensitive layer (hereinafter sometimes referred to as a coating liquid for photosensitive layer) is prepared. A coating solution for a photosensitive layer is applied onto a conductive substrate. Next, at least a portion of the solvent contained in the applied photosensitive layer coating solution is removed to form a photosensitive layer. The photosensitive layer coating liquid contains, for example, a charge generating agent, a hole transporting agent, an electron transporting agent, a binder resin, and a solvent. The coating liquid for the photosensitive layer is prepared by dissolving or dispersing a charge generating agent, a hole transporting agent, an electron transporting agent, and a binder resin in a solvent.

The solvent contained in the coating liquid for photosensitive layer is not particularly limited as long as it can dissolve or disperse each component contained in the coating liquid for photosensitive layer. Examples of the solvent include alcohols (more specifically, methanol, ethanol, isopropanol, and butanol, etc.), aliphatic hydrocarbons (more specifically, n-hexane, octane, and cyclohexane, etc.), and aromatic hydrocarbons. Hydrogen (more specifically, benzene, toluene, xylene, etc.), halogenated hydrocarbons (more specifically, dichloromethane, dichloroethane, carbon tetrachloride, 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.), Dimethyl formaldehyde, dimethyl formamide, and dimethyl sulfoxide are mentioned. These solvents may be used alone or in combination of two or more.

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

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

Examples of methods for removing at least a portion of the solvent contained in the photosensitive layer coating solution include heating, reduced pressure, or a combination of heating and reduced pressure. 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.

Note that the method for manufacturing a photoreceptor may further include a step of forming an intermediate layer as necessary. For the step of forming the intermediate layer, a known method can be selected as appropriate.

<Image forming device>
Next, an image forming apparatus including the photoreceptor 1 of this embodiment will be described. Hereinafter, a tandem type color image forming apparatus will be described as an example with reference to FIG. FIG. 4 is a cross-sectional view showing an example of an image forming apparatus.

The image forming apparatus 100 shown in FIG. 4 includes image forming units 40a, 40b, 40c, and 40d, a transfer belt 50, and a fixing device 54. Hereinafter, each of the image forming units 40a, 40b, 40c, and 40d will be referred to as an image forming unit 40 unless it is necessary to distinguish between them.

The image forming unit 40 includes an image carrier 30, a charging device 42, an exposure device 44, a developing device 46, a transfer device 48, and a cleaning member 52. The image carrier 30 is the photoreceptor 1 of this embodiment.

As already mentioned, according to the photoreceptor 1 of this embodiment, wear resistance can be improved. Therefore, by including the photoreceptor 1 as the image carrier 30, the durability of the image forming apparatus 100 can be improved.

An image carrier 30 is provided at the center of the image forming unit 40 . The image carrier 30 is provided so as to be rotatable in the direction of the arrow (counterclockwise). Around the image carrier 30, a charging device 42, an exposure device 44, a developing device 46, a transfer device 48, and a cleaning member 52 are arranged in the order listed from the upstream side in the rotational direction of the image carrier 30. provided.

Toner images of a plurality of colors (for example, four colors of black, cyan, magenta, and yellow) are sequentially superimposed on the recording medium P on the transfer belt 50 by each of the image forming units 40a to 40d.

The charging device 42 charges the surface (for example, the circumferential surface) of the image carrier 30 to, for example, positive polarity. The charging device 42 is, for example, a charging roller.

The exposure device 44 irradiates the surface of the charged image carrier 30 with exposure light. That is, the exposure device 44 exposes the surface of the charged image carrier 30 to light. As a result, an electrostatic latent image is formed on the surface of the image carrier 30. The electrostatic latent image is formed based on image data input to the image forming apparatus 100.

The developing device 46 supplies toner to the surface of the image carrier 30 and develops the electrostatic latent image as a toner image. The developing device 46 develops the electrostatic latent image as a toner image while the surface (for example, the peripheral surface) of the developing device 46 is in contact with the surface of the image carrier 30 . That is, the image forming apparatus 100 employs a contact development method. The developing device 46 is, for example, a developing roller. When the developer is a one-component developer, the developing device 46 supplies toner, which is the one-component developer, to the electrostatic latent image formed on the image carrier 30. When the developer is a two-component developer, the developing device 46 supplies toner of the toner and carrier contained in the two-component developer to the electrostatic latent image formed on the image carrier 30. In this way, the image carrier 30 carries a toner image.

Transfer belt 50 conveys recording medium P between image carrier 30 and transfer device 48 . The transfer belt 50 is an endless belt. The transfer belt 50 is provided so as to be rotatable in the direction of the arrow (clockwise).

The transfer device 48 transfers the toner image developed by the developing device 46 from the surface of the image carrier 30 to the transfer target. The object to be transferred is a recording medium P. Specifically, while the recording medium P is in contact with the surface of the image carrier 30, the transfer device 48 transfers the toner image from the surface of the image carrier 30 to the recording medium P. That is, the image forming apparatus 100 employs a direct transfer method. The transfer device 48 is, for example, a transfer roller.

The cleaning member 52 is brought into pressure contact with the surface of the image carrier 30, and the cleaning member 52 collects toner attached to the circumferential surface of the image carrier 30. The cleaning member 52 is, for example, a cleaning blade.

The recording medium P onto which the toner image has been transferred by the transfer device 48 is conveyed to the fixing device 54 by the transfer belt 50 . The fixing device 54 is, for example, a heating roller and/or a pressure roller. The unfixed toner image transferred by the transfer device 48 is heated and/or pressurized by the fixing device 54 . The toner image is fixed on the recording medium P by heating and/or pressurizing the toner image. As a result, an image is formed on the recording medium P.

Although an example of an image forming apparatus has been described above, the image forming apparatus is not limited to the image forming apparatus 100 described above. Although the image forming apparatus 100 described above is a color image forming apparatus, the image forming apparatus may be a monochrome image forming apparatus. In this case, the image forming apparatus only needs to include, for example, one image forming unit. Furthermore, although the image forming apparatus 100 described above employs a tandem system, the image forming apparatus may also employ, for example, a rotary system. Although the charging roller has been described as an example of the charging device 42, the charging device may be a charging device other than the charging roller (for example, a scorotron charger, a charging brush, or a corotron charger). Although the image forming apparatus 100 described above employs a contact developing method, the image forming apparatus may also employ a non-contact developing method. Although the image forming apparatus 100 described above employs a direct transfer method, the image forming apparatus may also employ an intermediate transfer method. When the image forming apparatus employs an intermediate transfer method, the transfer target corresponds to an intermediate transfer belt. Although the cleaning blade has been described as an example of the cleaning member 52, the cleaning member may also be a cleaning roller. Note that although the image forming unit 40 described above did not include a static eliminator, the image forming unit may further include a static eliminator.

<Process cartridge>
Next, with continued reference to FIG. 4, an example of a process cartridge including the photoreceptor 1 of this embodiment will be described. The process cartridge corresponds to each of the image forming units 40a to 40d. The process cartridge includes an image carrier 30. The image carrier 30 is the photoreceptor 1 of this embodiment. In addition to the image carrier 30, the process cartridge further includes at least one of a charging device 42 and a cleaning member 52.

As already mentioned, according to the photoreceptor 1 of this embodiment, wear resistance can be improved. Therefore, by including the photoreceptor 1 as the image carrier 30, the process cartridge has excellent durability.

In addition to the image carrier 30, the charging device 42, and the cleaning member 52, the process cartridge may further include at least one of an exposure device 44, a developing device 46, and a transfer device 48. The process cartridge may further include a static eliminator (not shown). The process cartridge is designed to be detachable from the image forming apparatus 100. Therefore, the process cartridge is easy to handle, and when the sensitivity characteristics of the image carrier 30 deteriorate, the process cartridge including the image carrier 30 can be easily and quickly replaced. The process cartridge including the photoreceptor 1 of this embodiment has been described above with reference to FIG.

Hereinafter, the present invention will be explained in more detail using Examples. However, the present invention is not limited in any way to the scope of the examples.

First, the following charge generating agent, electron transporting agent, hole transporting agent, and binder resin were prepared as materials for forming the photosensitive layer of the photoreceptor.

(charge generating agent)
The Y-type titanyl phthalocyanine described in the embodiment was prepared as a charge generating agent.

(electron transport agent)
Each of the compounds (10-E1), (11-E3), and (12-E2) described in the embodiment was prepared as an electron transport agent.

(hole transport agent)
As hole transport agents, compounds (20-H8), (20-H9), (21-H4), (22-H6), (23-H1), (23-H2), (23 -H3), (24-H7), and (25-H5) were prepared.

(binder resin)
As the binder resin, each of the polyarylate resins (R-1) to (R-7) described in the embodiment was synthesized.

(Synthesis of polyarylate resin (R-1))
A three-necked flask equipped with a thermometer, a three-way cock, and a dropping funnel was used as the reaction vessel. 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). 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 container were cooled until the temperature of the contents of the reaction container reached 10° C. to obtain alkaline aqueous solution A.

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

Chloroform solution B was slowly added dropwise to alkaline aqueous solution A using a dropping funnel over 110 minutes. The polymerization reaction was allowed to proceed by stirring the contents of the reaction vessel for 4 hours while adjusting the temperature (liquid temperature) of the contents of the reaction vessel at 15±5°C. The upper layer (aqueous layer) of the contents of the reaction vessel was removed using a decant to obtain an organic layer. Then, ion exchange 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 five times to obtain a water-washed organic layer. 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 taken out precipitate was vacuum dried at a temperature of 70° C. for 12 hours. As a result, polyarylate resin (R-1) was obtained.

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

(Synthesis of polyarylate resin (R-3))
The dicarboxylic acid dichloride (32.4 mmol) of compound (DC-3) was added to the dicarboxylic acid dichloride (16.2 mmol) of compound (DC-3) and the dicarboxylic acid dichloride (16.2 mmol) of compound (DC-4). ) Polyarylate resin (R-3) was obtained in the same manner as in the synthesis of polyarylate resin (R-1) except that the polyarylate resin (R-3) was changed to

(Synthesis of polyarylate resin (R-4))
The same method as the synthesis of polyarylate resin (R-1) was carried out, except that compound (BP-1-1) (30.9 mmol) was changed to compound (BP-1-2) (30.9 mmol). A polyarylate resin (R-4) was obtained.

(Synthesis of polyarylate resin (R-5))
The same method as for the synthesis of polyarylate resin (R-1) was used, except that compound (BP-1-1) (30.9 mmol) was changed to compound (BP-1-3) (30.9 mmol). A polyarylate resin (R-5) was obtained.

(Synthesis of polyarylate resin (R-6))
The same method as for the synthesis of polyarylate resin (R-1) was used, except that compound (BP-1-1) (30.9 mmol) was changed to compound (BP-1-4) (30.9 mmol). A polyarylate resin (R-6) was obtained.

(Synthesis of polyarylate resin (R-7))
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) Polyarylate resin (R-7) was obtained in the same manner as in the synthesis of polyarylate resin (R-1), except that the amount was changed to (20.6 mmol).

Average viscosity of the obtained polyarylate resins (R-1), (R-2), (R-3), (R-4), (R-5), (R-6) and (R-7) The molecular weights were 50,500, 51,000, 50,000, 45,000, 47,300, 45,500, and 48,700, respectively.

¹ H-NMR spectra of the obtained polyarylate resins (R-1) to (R-7) were measured using a proton nuclear magnetic resonance spectrometer (manufactured by JASCO Corporation, 300 MHz). _CDCl3 was used as the solvent. Tetramethylsilane (TMS) was used as an internal standard sample. As a representative example of polyarylate resins (R-1) to (R-7), the chemical shift value of polyarylate resin (R-7) is shown below. It was confirmed from the chemical shift value that polyarylate resin (R-7) was obtained. It was confirmed that polyarylate resins (R-1) to (R-6) were obtained using the same method.

Polyarylate resin (R-7): 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).

In addition, each of polyarylate resins (RA) to (RG) were also prepared as binder resins used in comparative examples. Each of the polyarylate resins (RA) to (RC) is represented by the following chemical formulas (RA) to (RC). Note that the number attached to the lower right of each repeating unit indicates the percentage (unit: %) 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) used in the comparative example 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), 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 respectively 25.0%, 25.0%, 25.0%, 15.0%, and It is 10.0%.

The polyarylate resin (RE) used in the comparative example contains only the following repeating unit (BP-C) as a bisphenol-derived repeating unit. The polyarylate resin (RE) 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-C), percentage of the number of repeating units (3), percentage of the number of repeating units (DC-T) with respect to the total number of repeating units contained in the polyarylate resin (RE) , and the percentage of the number of repeating units (DC-I) are 50.0%, 25.0%, 15.0%, and 10.0%, respectively.

The polyarylate resin (RF) used in the comparative example contains only the following repeating unit (BP-A) as a bisphenol-derived repeating unit. The polyarylate resin (RF) 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 (3), percentage of the number of repeating units (DC-T) with respect to the total number of repeating units contained in the polyarylate resin (RF) , and the percentage of the number of repeating units (DC-I) are 50.0%, 25.0%, 15.0%, and 10.0%, respectively.

The polyarylate resin (RG) used in the comparative example contains only the following repeating unit (BP-Z) as a repeating unit derived from bisphenol. The polyarylate resin (RG) 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-Z), percentage of the number of repeating units (3), percentage of the number of repeating units (DC-T) with respect to the total number of repeating units contained in the polyarylate resin (RG) , and the percentage of the number of repeating units (DC-I) are 50.0%, 25.0%, 15.0%, and 10.0%, respectively.

In addition, the viscosity average molecular weight of the polyarylate resins (RA), (RB), (RC), (RD), (RE), (RF) and (RG) were 45,300, 51,000, 46,700, 46,800, 51,000, 45,000, and 44,400, respectively.

Types of bisphenol-derived repeating units, ratio n ₁ /n ₂ , and dicarboxylic acid-derived repeating units of the prepared polyarylate resins (R-1) to (R-7) and (RA) to (RG) The types are shown in Table 3. “-” in Table 3 indicates that there is no corresponding value.

<Manufacture of photoreceptor>
Photoreceptors (A-1) to (A-17) and (B-1) to (B-7) were manufactured using the above-mentioned charge generating agent, electron transporting agent, hole transporting agent, and binder resin. .

(Manufacture of photoreceptor (A-1))
3 parts by mass of Y-type titanyl phthalocyanine as a charge generating agent, 70 parts by mass of compound (23-H1) as a hole transporting agent, 100 parts by mass of polyarylate resin (R-1) as a binder resin, and 100 parts by mass of a polyarylate resin (R-1) as an electron transporting agent. 30 parts by mass of compound (10-E1) and 800 parts by mass of tetrahydrofuran as a solvent were mixed for 50 hours using a ball mill to obtain a coating solution for a photosensitive layer. A coating solution for a photosensitive layer was applied onto a conductive substrate (a drum-shaped support made of aluminum) by a dip coating method. The applied photosensitive layer coating solution was dried with hot air at 120° C. for 60 minutes. In this way, a photosensitive layer (thickness: 28 μm) was formed on the conductive substrate to obtain a photoreceptor (A-1). In the photoreceptor (A-1), a single photosensitive layer was provided directly on the conductive substrate.

(Manufacture of photoreceptors (A-2) to (A-17) and (B-1) to (B-7))
Photoreceptors (A-2) to (A- 17) and each of (B-1) to (B-7) were produced.

<Evaluation of sensitivity characteristics>
The sensitivity characteristics of each of the photoreceptors (A-1) to (A-17) and (B-1) to (B-7) were evaluated under an environment of a temperature of 23°C and a relative humidity of 50% RH. . Specifically, the surface of the photoreceptor was charged to +750V using a drum sensitivity tester (manufactured by Gentec Corporation). Next, monochromatic light (wavelength: 780 nm, exposure amount: 0.7 μJ/cm ² ) was extracted from the light of the halogen lamp using a band pass filter, and was irradiated onto the surface of the photoreceptor. The surface potential of the photoreceptor was measured 40 milliseconds after the end of the monochromatic light irradiation. The measured surface potential was defined as the post-exposure potential V _L (unit: +V) of the photoreceptor. Table 4 shows the post-exposure potential V _L of the photoreceptor. The smaller the absolute value of the post-exposure potential V _L is, the better the sensitivity characteristics of the photoreceptor are.

<Evaluation of wear resistance>
Abrasion resistance was evaluated for each of the photoreceptors (A-1) to (A-17) and (B-1) to (B-7). An image forming apparatus ("FS-C5250DN" manufactured by Kyocera Document Solutions Co., Ltd.) was used as an evaluation machine for evaluating the abrasion resistance. This image forming apparatus was equipped with a charging roller and a cleaning blade. Further, this image forming apparatus employed a contact development method and a direct transfer method.

First, the film thickness T1 of the photosensitive layer of the photoreceptor was measured. Next, the photoreceptor was mounted on an evaluation machine. Next, 50,000 sheets of paper (“Kyocera Document Solutions Brand Paper VM-A4” sold by Kyocera Document Solutions Co., Ltd.) were evaluated using an evaluation machine under a normal temperature and normal humidity environment (temperature 23°C and relative humidity 50% RH). Image I (pattern image with a printing rate of 1%) was continuously printed. After printing, the film thickness T2 of the photosensitive layer of the photoreceptor was measured. Then, from the formula "Average wear amount = (T1-T2)/50", the average amount of wear (unit: μm) when 1000 sheets were printed was determined. Table 4 shows the average wear amount determined. The smaller the average amount of wear, the better the wear resistance of the photoreceptor.

In Table 4, HTM, resin, ETM, and abrasion amount respectively indicate the hole transport agent, binder resin, electron transport agent, and average abrasion amount when 1000 sheets were printed. In Table 4, "not dissolved" indicates that the binder resin was not dissolved in the solvent during the preparation of the photosensitive layer coating solution, and the photosensitive layer could not be formed.

As shown in Table 4, the photosensitive layer of photoreceptors (A-1) to (A-17) is a single layer, and includes a charge generating agent, a hole transporting agent, an electron transporting agent, and a polyarylate resin ( More specifically, it contained any one of polyarylate resins (R-1) to (R-7). Each of the polyarylate resins (R-1) to (R-7) contains at least a repeating unit (1), a repeating unit (2), and a repeating unit (3), and the number n of repeating units (2) is The ratio n ₁ /n ₂ of the number n ₁ of repeating units ( ₁ ) to 2 was 1.0 or more. The photosensitive layer contains any of compounds (10), (11), or (12) (more specifically, compounds (10-E1), (11-E3), and (12-E2)) as an electron transport agent. ). The abrasion loss of the photoreceptors (A-1) to (A-17) was 0.07 μm/1000 sheets or less, and the photoreceptors (A-1) to (A-17) had excellent abrasion resistance. In addition, the post-exposure potential V _L of the photoreceptors (A-1) to (A-17) is +129V or less, and the sensitivity characteristics of the photoreceptors (A-1) to (A-17) are sufficient for practical use. was able to maintain this.

From the above, it was shown that the photoreceptor according to the present invention has excellent wear resistance. Since the photoreceptor according to the present invention has excellent wear resistance, a process cartridge and an image forming apparatus including the photoreceptor according to the present invention have excellent durability.

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

1: Photoreceptor (electrophotographic photoreceptor)
2: Conductive substrate 3: Photosensitive layer 30: Image carrier 42: Charging device 44: Exposure device 46: Developing device 48: Transfer device 100: Image forming device P: Recording medium

Claims (8)

comprising a conductive substrate and a photosensitive layer,
The photosensitive layer is a single layer,
The photosensitive layer contains a charge generating agent, a hole transporting agent, an electron transporting agent, and a polyarylate resin,
The polyarylate resin includes at least a repeating unit represented by the chemical formula (1-1) , a repeating unit represented by the chemical formula (2), and a repeating unit represented by the chemical formula (3), and the polyarylate resin has the chemical formula ( The ratio n ₁ /n 2 of the number n ₁ of repeating units represented by the chemical formula (1-1) to the number n ₂ of repeating units represented by ₂ ) is 2.0 or more and 5.0 or less. ,
The electron transport agent includes a compound represented by chemical formula (11-E3),
The electrophotographic photoreceptor, wherein the hole transport agent is a compound represented by chemical formula (23-H1) or chemical formula (23-H3) .

The electrophotographic photoreceptor according to claim 1 , wherein the polyarylate resin further includes a repeating unit represented by chemical formula (4).

The electrophotographic photoreceptor according to claim 1 or 2 , wherein the photosensitive layer is provided as an outermost layer. A process cartridge comprising the electrophotographic photoreceptor according to any one of claims 1 to 3 . an image carrier;
a charging device that charges the surface of the image carrier;
an exposure device that exposes the charged surface of the image carrier to form an electrostatic latent image on the surface of the image carrier;
a developing device that develops the electrostatic latent image as a toner image;
a transfer device that transfers the toner image from the image carrier to a transfer target;
An image forming apparatus, wherein the image carrier is an electrophotographic photoreceptor according to any one of claims 1 to 3 . The object to be transferred is a recording medium,
The image forming apparatus according to claim 5 , wherein the transfer device transfers the toner image from the image carrier to the recording medium while the recording medium is in contact with the surface of the image carrier. The image forming apparatus according to claim 5 or 6 , wherein the developing device develops the electrostatic latent image as the toner image while the developing device is in contact with the surface of the image carrier. The image forming apparatus according to claim 5, wherein the charging device is a charging roller.

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