JP7298271B2 - electrophotographic photoreceptor - Google Patents

Description

The present invention relates to an electrophotographic photoreceptor.

An electrophotographic photoreceptor is used as an image carrier in an electrophotographic image forming apparatus (for example, a printer or a multifunction machine). An electrophotographic photoreceptor has a photosensitive layer. As the electrophotographic photoreceptor, for example, a single-layer electrophotographic photoreceptor and a laminated 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. A 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 for this photosensitive layer is a polyarylate resin having a structure represented by the following chemical formula.

Japanese Patent Application Laid-Open No. 2003-322982

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

The present invention has been made in view of the above problems, and an object of the present invention is to provide an electrophotographic photoreceptor which is excellent in wear resistance and can suppress the turning-up of a cleaning blade (hereinafter referred to as blade-turning). be.

The electrophotographic photoreceptor of the present invention comprises a conductive substrate and a photosensitive layer. The photosensitive layer contains a charge generating agent, a hole transporting agent, a binder resin, and fluororesin particles. The binder resin includes polyarylate resin. The polyarylate resin contains repeating units represented by general formula (1), repeating units represented by chemical formula (2), and repeating units represented by 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 the 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. show. Alternatively, R ¹ and R ² each represent a methyl group, and R ³ and R ⁴ combined together represent a cycloalkylidene group having 5 or 6 carbon atoms.

The electrophotographic photoreceptor of the present invention is excellent in wear resistance and can suppress the occurrence of blade curling.

1 is a partial cross-sectional view of a laminated electrophotographic photoreceptor, which is an example of an electrophotographic photoreceptor according to an embodiment of the present invention; FIG. 1 is a partial cross-sectional view of a laminated electrophotographic photoreceptor, which is an example of an electrophotographic photoreceptor according to an embodiment of the present invention; FIG. 1 is a partial cross-sectional view of a laminated electrophotographic photoreceptor, which is an example of an electrophotographic photoreceptor according to an embodiment of the present invention; FIG. 1 is a partial cross-sectional view of a single-layer electrophotographic photoreceptor, which is an example of an electrophotographic photoreceptor according to an embodiment of the present invention; FIG. 1 is a partial cross-sectional view of a single-layer electrophotographic photoreceptor, which is an example of an electrophotographic photoreceptor according to an embodiment of the present invention; FIG. 1 is a partial cross-sectional view of a single-layer electrophotographic photoreceptor, which is an example of an electrophotographic photoreceptor according to an embodiment of the present invention; FIG.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail. However, the present invention is by no means limited to the following embodiments. The present invention can be implemented with appropriate modifications within the scope of the purpose of the present invention. It should be noted that descriptions of overlapping descriptions may be omitted as appropriate, but the gist of the invention is not limited. Hereinafter, compounds and derivatives thereof may be collectively referred to by adding "system" to the name of the compound. In addition, when the name of a polymer is expressed by adding "system" to the name of a compound, it means that the repeating unit of the polymer is derived from the compound or its derivative.

First, the substituents used in this specification are described. 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 alkyl groups 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, linear and branched heptyl groups, and linear 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 described as examples of the alkyl group below, it is a group having the corresponding number of carbon atoms.

Each alkoxy group having from 1 to 8 carbon atoms and an alkoxy group having from 1 to 3 carbon atoms is linear or branched and unsubstituted unless otherwise specified. Examples of alkoxy groups having 1 to 8 carbon atoms include methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, sec-butoxy, tert-butoxy, n-pentoxy, 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, 1,2,2-trimethylpropoxy, 1-ethylbutoxy, 2-ethylbutoxy, 3-ethylbutoxy, linear and branched heptyloxy groups, and linear and A branched octyloxy group can be mentioned. Examples of the alkoxy group having 1 to 3 carbon atoms are groups having the corresponding number of carbon atoms among the groups described as examples of the alkoxy group having 1 to 8 carbon atoms.

Cycloalkanes having 5 to 7 carbon atoms are unsubstituted unless otherwise specified. Cycloalkanes having 5 to 7 carbon atoms include, for example, cyclopentane, cyclohexane, and cycloheptane. The substituents used in the present specification have been described above.

<Electrophotographic photoreceptor>
The present embodiment relates to an electrophotographic photoreceptor (hereinafter sometimes referred to as a photoreceptor). The photoreceptor of this embodiment includes a conductive substrate and a photosensitive layer. The photosensitive layer contains a charge generating agent, a hole transporting agent, a binder resin, and fluororesin particles. The photoreceptor is, for example, a single-layer electrophotographic photoreceptor (hereinafter sometimes referred to as a single-layer photoreceptor) or a laminated electrophotographic photoreceptor (hereinafter sometimes referred to as a laminated photoreceptor). is.

(Laminated photoreceptor)
Next, a laminated photoreceptor 1, which is an example of a photoreceptor, will be described with reference to FIGS. 1 to 3. FIG. 1 to 3 each show a partial cross-sectional view of the laminated photoreceptor 1. FIG.

As shown in FIG. 1, the laminated photoreceptor 1 includes, for example, a conductive substrate 2 and a photosensitive layer 3. As shown in FIG. The photosensitive layer 3 includes a charge generation layer 3a and a charge transport layer 3b. In other words, the laminated photoreceptor 1 includes the charge generation layer 3a and the charge transport layer 3b as the photosensitive layer 3. As shown in FIG. 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 photoreceptor 1, the charge generation layer 3a may be provided on the conductive substrate 2, and the charge transport layer 3b may be provided on the charge generation layer 3a. Alternatively, as shown in FIG. 2, in the laminated photoreceptor 1, the charge transport layer 3b may be provided on the conductive substrate 2, and the charge generation layer 3a may be provided on the charge transport layer 3b.

As shown in FIG. 3, the laminated photoreceptor 1 may include a conductive substrate 2, a photosensitive layer 3, and an intermediate layer 4 (undercoat layer). An 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 photoreceptor 1, the photosensitive layer 3 may be provided directly on the conductive substrate 2. FIG. Alternatively, as shown in FIG. 3, in the laminated photoreceptor 1, the photosensitive layer 3 may be provided on the conductive substrate 2 with the intermediate layer 4 interposed therebetween. When the laminated photoreceptor 1 is provided with the intermediate layer 4, as shown in FIG. A charge transport layer 3b may be provided thereon. 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 photoreceptor 1 may include a conductive substrate 2, a photosensitive layer 3, and a protective layer 5 (see FIG. 6). A protective layer 5 is provided on the photosensitive layer 3 . As shown in FIGS. 1 and 2, a photosensitive layer 3 (for example, a charge transport layer 3b or a charge generation layer 3a) may be provided as the outermost layer of the multilayer photoreceptor 1. FIG. Alternatively, the protective layer 5 may be provided as the outermost layer of the laminated photoreceptor 1 .

As shown in FIG. 1, the photosensitive layer 3 (more specifically, the charge transport layer 3b) is preferably provided as the outermost surface layer of the laminated photoreceptor 1. As shown in FIG. It is more preferable that the charge transport layer 3b is a single layer and provided as the outermost layer of the multilayer photoreceptor 1 . By providing a charge transport layer 3b containing a polyarylate resin (PA) and fluororesin particles, which will be described later, as the outermost layer, the abrasion resistance of the multilayer photoreceptor 1 is further improved, and the occurrence of blade curling is further reduced. can be suppressed.

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

The charge transport layer 3b contains a hole transport agent, a binder resin, and fluororesin particles. The charge transport layer 3b may contain additives as required. Although the thickness of the charge transport layer 3b is not particularly limited, it 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 photoreceptor 1 has been described above with reference to FIGS. 1 to 3. FIG.

(Single layer photoreceptor)
Next, a single-layer photoreceptor 10, which is an example of a photoreceptor, will be described with reference to FIGS. 4 to 6. FIG. 4 to 6 each show a partial cross-sectional view of the single-layer photoreceptor 10. FIG.

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

As shown in FIG. 5, the single-layer photoreceptor 10 may include a conductive substrate 2, a single-layer photoreceptor 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 type photosensitive layer 3c may be provided directly on the conductive substrate 2. FIG. Alternatively, as shown in FIG. 5, the single-layer type photosensitive layer 3c may be provided on the conductive substrate 2 with the intermediate layer 4 interposed therebetween.

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

As shown in FIGS. 4 and 5, it is preferable that the photosensitive layer 3 (more specifically, the single-layer photosensitive layer 3c) is provided as the outermost surface layer of the single-layer photoreceptor . By providing a single-layer photosensitive layer 3c containing a polyarylate resin (PA) and fluororesin particles, which will be described later, as the outermost layer, the abrasion resistance of the single-layer photosensitive member 10 is further improved, and blade curling is prevented. The occurrence can be further suppressed.

The single-layer type photosensitive layer 3c contains a charge generating agent, a hole transporting agent, a binder resin, and fluororesin particles. The single-layer type photosensitive layer 3c may further contain an electron transport agent. The single-layer type photosensitive layer 3c may contain additives as necessary.

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

(binder resin)
The photosensitive layer contains a polyarylate resin as a binder resin. The polyarylate resin contains repeating units represented by general formula (1), repeating units represented by chemical formula (2), and repeating units represented by 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 the 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. show. Alternatively, in general formula (1), R ¹ and R ² each represent a methyl group, and R ³ and R ⁴ are combined 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 respectively referred to as the repeating unit (1) and the repeating unit (2 ), and repeating unit (3). Further, the repeating unit (1), the repeating unit (2) and the repeating unit (3) are included, and 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 A polyarylate resin having a polyarylate of 1.0 or more may be referred to as a polyarylate resin (PA).

A polyarylate resin (PA) can improve the wear resistance of the photoreceptor when it is contained in the photoreceptor layer. The reason is presumed as follows.

First, the polyarylate resin (PA) contains repeating units (2) and repeating units (3). Thereby, the abrasion resistance of the photoreceptor can be improved.

Second, the polyarylate resin (PA) contains repeating units (1). This can improve the solubility of the polyarylate resin (PA) in the solvent for forming the photosensitive layer. 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 in solubility. By improving the solubility of the polyarylate resin (PA), the photosensitive layer can be suitably formed, and the wear resistance of the photoreceptor can be improved.

Next, general formula (1) will be described 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.

The cycloalkylidene group having 5 or 6 carbon atoms represented by R ³ and R ⁴ in general formula (1) combined with each other includes 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) are represented by chemical formula (1-1), chemical formula (1-2), chemical formula (1-3), chemical formula (1-4), and chemical formula (1-5). repeating units. Hereinafter, repeating units represented by chemical formulas (1-1), chemical formula (1-2), chemical formula (1-3), chemical formula (1-4), and chemical formula (1-5) are referred to as repeating units ( 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 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 it. 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 wear resistance of the photoreceptor can be improved. . In order to improve the abrasion resistance of the photoreceptor, the ratio _n1 / _n2 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 photosensitive layer, the ratio n ₁ /n ₂ should be 1.0, 2.0, It is also preferably within 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 _n1 / _n2 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 compound (BP-2) will be described later.

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

Specific examples of polyarylate resins (PA) include the following polyarylate resins.
A polyarylate resin containing 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 (referred to as polyarylate resin (I) there is);
A 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 (referred to as polyarylate resin (II) there is);
A 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 (referred to as polyarylate resin (III) there is);
A 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 (referred to as polyarylate resin (IV) there is);
A 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 (referred to as polyarylate resin (V) ₎ ; and a polyarylate resin ( _polyarylate resin (VI ).

More specific examples of the polyarylate resin (PA) include polyarylate resins represented by chemical formulas (R-1) to (R-6) (hereinafter referred to as polyarylate resins (R-1) to (R -6)) may be mentioned. In the chemical formulas (R-1) to (R-6), the number attached to the lower right of each repeating unit is the percentage (%) of the number of each repeating unit to the total number of repeating units contained in the polyarylate resin ). 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. For convenience of description, two repeating units (3) are shown 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) was 50.0% (two repeating units (3) is 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 adjacently bonded to each other. 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). Polyarylate resins (PA) can be, for example, random copolymers, alternating copolymers, periodic copolymers, or block copolymers.

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

The viscosity average molecular weight of the polyarylate resin (PA) is preferably 10,000 or more, more preferably 20,000 or more, still more 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 wear 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.

A method for producing the polyarylate resin (PA) is not particularly limited. Examples of a method for producing a polyarylate resin (PA) include a method of condensation polymerization of bisphenol for forming bisphenol-derived repeating units and dicarboxylic acid for forming dicarboxylic acid-derived repeating units. For polycondensation, known synthesis methods (eg, solution polymerization, melt polymerization, or interfacial polymerization) can be employed.

As bisphenol for constituting the bisphenol repeating unit of polyarylate resin (PA), for example, compounds represented by general formula (BP-1) and chemical formula (BP-2) (hereinafter referred to as compound (BP-1) and (BP-2) may be described). As the dicarboxylic acid for constituting the dicarboxylic acid repeating unit of the polyarylate resin (PA), for example, a compound represented by the chemical formula (DC-3) (hereinafter sometimes referred to as compound (DC-3)) is mentioned. 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).

Preferred examples of the 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)).

A bisphenol for forming a bisphenol-derived repeating unit may be used after being derivatized to an aromatic diacetate. A dicarboxylic acid for forming a dicarboxylic acid-derived repeating unit may be used after being derivatized. Examples of derivatives of dicarboxylic acids include dicarboxylic acid dichlorides, dicarboxylic acid dimethyl esters, dicarboxylic acid diethyl esters, and dicarboxylic acid anhydrides. A 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.

One or both of a base and a catalyst may be added in the polycondensation of bisphenol and dicarboxylic acid. 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 a polyarylate resin (PA) as a binder resin. Moreover, the photosensitive layer may further contain a binder resin other than the 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 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, phenol resins, urea resins, melamine resins, and other crosslinkable thermosetting resins), and photocurable resins (more specifically, epoxy-acrylic acid resins and urethane-acrylic acid copolymers). mentioned.

(Fluororesin particles)
When the photosensitive layer contains fluororesin particles, it is possible to suppress the occurrence of blade curling. First, to facilitate understanding, blade turnover will be described. 2. Description of the Related Art In an image forming apparatus, a cleaning blade contacts the surface of a photoreceptor, thereby recovering residual toner and toner external additives (hereinafter referred to as toner or the like) on the surface of the photoreceptor. For example, when the counter contact method (leading method) is employed, the direction from the base end to the tip of the cleaning blade at the point of contact between the tip of the cleaning blade and the surface of the photoreceptor is the rotation direction of the photoreceptor. and in the opposite direction. However, the cleaning blade is turned over due to friction with the photoreceptor during printing, and at the point of contact between the tip of the cleaning blade and the surface of the photoreceptor, the direction from the base end to the tip of the cleaning blade is the rotation of the photoreceptor. It may be the same direction as the direction. Such a phenomenon is blade turn-up. When the blade turns over, the toner or the like slips through the contact point between the photoreceptor and the cleaning blade, and the toner or the like remaining on the surface of the photoreceptor is not collected. In addition, when the blade is turned over, an abnormal noise is generated when forming an image using the image forming apparatus.

Here, the following first and second advantages can be obtained by including fluororesin particles in the photosensitive layer of the photoreceptor of the present embodiment. A first advantage is described. The fluororesin particles form irregularities on the surface of the photoreceptor (for example, the photosensitive layer). Such unevenness reduces the contact area between the surface of the photoreceptor and the cleaning blade. A smaller contact area reduces the dynamic friction coefficient of the surface of the photoreceptor. Therefore, it is possible to suppress the occurrence of blade curling caused by friction between the photoreceptor and the cleaning blade.

Next, a second advantage will be explained. When an image is formed using an image forming apparatus for a long period of time, the surface of the photoreceptor included in the image forming apparatus may gradually wear out. When the surface of the photoreceptor is worn, the number of fluororesin particles exposed on the surface of the photoreceptor increases. The dynamic friction coefficient of fluororesin is smaller than that of other materials (for example, silica). Therefore, even when the number of fluororesin particles exposed on the surface of the photoreceptor increases, the coefficient of dynamic friction on the surface of the photoreceptor is less likely to increase. Therefore, it is possible to suppress the occurrence of blade curling caused by friction between the photoreceptor and the cleaning blade.

Examples of fluororesin particles include polytetrafluoroethylene particles, perfluoroalkoxyalkane particles, perfluoroethylene propene copolymer particles, ethylene/tetrafluoroethylene copolymer particles, polyvinylidene fluoride particles, and polyvinyl fluoride particles. Hereinafter, "polytetrafluoroethylene" may be referred to as "PTFE". PTFE particles are preferable as the fluororesin particles.

The average primary particle size of the fluororesin particles is preferably 0.1 μm or more and 12.0 μm or less, more preferably 0.6 μm or more and 10.0 μm or less. When the average primary particle size of the fluororesin particles is 0.1 μm or more, moderate unevenness is formed on the surface of the photoreceptor (for example, the photosensitive layer). As a result, the coefficient of dynamic friction on the surface of the photoreceptor is reduced, and the occurrence of blade curling can be suppressed. On the other hand, when the average primary particle size of the fluororesin particles is 12.0 μm or less, clogging is less likely to occur when the photosensitive layer coating liquid is filtered, and the photosensitive layer can be produced favorably.

Here, the average primary particle size of the fluororesin particles is the projected area circle equivalent diameter (Heywood diameter ) means the number average value.

The content of the fluororesin particles is preferably 3% by mass or more and 11% by mass or less with respect to the mass of the binder resin. When the content of the fluororesin particles is 3% by mass or more, moderate unevenness is formed on the surface of the photoreceptor (for example, the photosensitive layer). As a result, the coefficient of dynamic friction on the surface of the photoreceptor is reduced, and the occurrence of blade curling can be suppressed. On the other hand, when the content of the fluororesin particles is 11% by mass or less, the fluororesin particles are less likely to precipitate in the coating liquid for the photosensitive layer, and the photosensitive layer can be suitably produced.

In order to suppress blade curling, the dynamic friction coefficient of the surface of the photosensitive layer is preferably 0.50 or less, more preferably 0.35 or less. Although the lower limit of the coefficient of dynamic friction of the surface of the photosensitive layer is not particularly limited, it is, for example, 0.10. A preferable range of the dynamic friction coefficient of the surface of the photosensitive layer is a preferable range of the dynamic friction coefficient measured when the photoreceptor is not used.

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

Preferable examples of the hole transport agent include compounds represented by general formulas (20), (21), and (22) (hereinafter referred to as compounds (20), (21), and (22) may be mentioned). The photosensitive layer contains the compound (20), (21), or (22) which is a hole transport agent together with the polyarylate resin (PA) and the fluororesin particles, without impairing the sensitivity characteristics of the photoreceptor. , the wear resistance of the photoreceptor can be further improved, and the occurrence of blade curling can be further suppressed.

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

In general formula (20), when a1 represents an integer of 2 or more and 5 or less, a plurality of R ²¹ may be the same or different. When a2 represents an integer of 2 or more and 5 or less, a plurality of R ²² may be the same or different. When adjacent two of R ²⁵ , R ²⁶ , R ²⁷ , R ²⁸ and R ²⁹ are joined together to form a ring, the ring and R ²⁵ , R ²⁶ , R ²⁷ , R ²⁸ and It is condensed with the phenyl group to which R ²⁹ is attached to form a bicyclic condensed ring group. In this case, the fusion site between the ring and the phenyl group may contain a double bond.

In general formula (20), R ²¹ and R ²² each independently preferably represent an alkyl group having 1 to 8 carbon atoms, more preferably an alkyl group having 1 to 3 carbon atoms. , more preferably represents a methyl group. Each of R ²³ and R ²⁴ preferably independently represents a phenyl group optionally substituted with an alkyl group having 1 to 8 carbon atoms, or a hydrogen atom. The phenyl group optionally substituted by an alkyl group having 1 to 8 carbon atoms represented by R ²³ and R ²⁴ is preferably a phenyl group optionally substituted by an alkyl group having 1 to 3 carbon atoms. A phenyl group substituted with an alkyl group having 1 to 3 atoms is more preferable, a methylphenyl group is still more preferable, and a 4-methylphenyl group is particularly preferable. R ²⁵ , R ²⁶ , R ²⁷ , R ²⁸ and R ²⁹ 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 ²⁵ , R ²⁶ , R ²⁷ , R ²⁸ and R ²⁹ is preferably an alkyl group having 1 to 6 carbon atoms, such as methyl group, ethyl group, or An n-butyl group is more preferred. The alkoxy group having 1 to 8 carbon atoms represented by R ²⁵ , R ²⁶ , R ²⁷ , R ²⁸ and R ²⁹ is preferably an alkoxy group having 1 to 3 carbon atoms, more preferably a methoxy group. When adjacent two of R ²⁵ , R ²⁶ , R ²⁷ , R ²⁸ and R ²⁹ are combined to form a ring, such a ring is preferably a cycloalkane having 5 to 7 carbon atoms, Cyclohexane is more preferred. a1 and a2 preferably each independently represent 0 or 1;

In general formula (21), R ³¹ to R ³⁶ each independently represent an alkyl group having 1 to 8 carbon atoms or a phenyl group. 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 represents 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 each independently represent 0 or 1;

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

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

In general formula (22), R ⁴¹ to R ⁴⁶ 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. f1, f2, f4, and f5 each independently represent an integer of 0 or more and 5 or less. f3 and f6 each independently represent an integer of 0 or more and 4 or less.

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

In general formula (22), each of R ⁴¹ to R ⁴⁶ preferably independently represents an alkyl group having 1 to 8 carbon atoms, more preferably an alkyl group having 1 to 3 carbon atoms. , a methyl group or an ethyl group. f1, f2, f4, and f5 preferably each independently represent an integer of 0 or more and 2 or less. f3 and f6 preferably represent zero. The diphenylaminophenylethenyl group having R ⁴⁴ , R ⁴⁵ and R ⁴⁶ is bonded to the diphenylaminophenylethenyl group having R ⁴¹ , R ⁴² and R ⁴³ at the ortho or para position of the phenyl group. preferably.

More preferred examples of hole transport agents include compounds represented by chemical formulas (HTM-1) to (HTM-9) (hereinafter referred to as compounds (HTM-1) to (HTM-9), respectively). sometimes).

Compounds (HTM-1) to (HTM-4) are each suitable examples of compound (20). Compounds (HTM-5) to (HTM-7) are each suitable examples of compound (21). Compounds (HTM-8) to (HTM-9) are each suitable examples of compound (22).

When the photoreceptor is a laminated photoreceptor, the content of the hole transport agent is preferably 10 parts by mass or more and 200 parts by mass or less, and 20 parts by mass or more and 100 parts by mass, based on 100 parts by mass of the binder resin. It is more preferably 40 parts by mass or more and 50 parts by mass or less. When the photoreceptor is a single-layer type photoreceptor, the content of the hole transport agent is preferably 50 parts by mass or more and 200 parts by mass or less, and 50 parts by mass or more and 70 parts by mass with respect to 100 parts by mass of the binder resin. Part or less is more preferable.

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

A phthalocyanine pigment is a pigment having a phthalocyanine structure. Examples of phthalocyanine pigments include metal-free phthalocyanines and metal phthalocyanines. Metal phthalocyanines include, for example, titanyl phthalocyanine, hydroxygallium phthalocyanine, and chlorogallium phthalocyanine. A 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 amorphous. 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 sometimes referred to as α-type, β-type, and Y-type titanyl phthalocyanine).

For example, it is preferable to use a photoreceptor 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 facsimile using a light source such as a semiconductor laser). As the charge generating agent, a phthalocyanine-based pigment is preferred, metal-free phthalocyanine or titanyl phthalocyanine is more preferred, titanyl phthalocyanine is still more preferred, and Y-type titanyl phthalocyanine is particularly preferred, since it has a high quantum yield in a wavelength region of 700 nm or more. .

Y-type titanyl phthalocyanine has a main peak at, for example, a Bragg angle (2θ±0.2°) of 27.2° in its 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 its 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 in a sample holder of an X-ray diffraction device (for example, "RINT (registered trademark) 1100" manufactured by Rigaku Corporation), and the X-ray tube Cu, tube voltage 40 kV, tube current 30 mA, Also, the X-ray diffraction spectrum is measured under the condition that the wavelength of the 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. A main peak is determined from the obtained X-ray diffraction spectrum, and the Bragg angle of the main peak is read.

When the photoreceptor is a layered photoreceptor, the content of the charge generating agent 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 photoreceptor is a single layer type photoreceptor, the content of the charge generating agent is preferably 0.1 parts by mass or more and 50 parts by mass or less, and preferably 0.5 parts by mass with respect to 100 parts by mass of the binder resin. It is more preferable that the amount is not less than 30 parts by mass and not more than 30 parts by mass.

(base resin)
The charge generation layer may contain a base resin. Examples of the base resin are the same as other binder resins contained in the charge transport layer.

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

(combination of materials)
In order to improve the wear resistance of the photoreceptor and suppress the occurrence of blade curling, the combination of polyarylate resin and fluororesin particles is the combination No. 1 shown in Table 1. Each of D1 to D20 is preferred. For the same reason, the combination of polyarylate resin and fluororesin particles is the combination No. 1 shown in Table 1. Each of D1 to D20, and the charge generating agent is more preferably Y-type titanyl phthalocyanine.

In order to improve the wear resistance of the photoreceptor and suppress the occurrence of blade curling, the combination of polyarylate resin, fluororesin particles, and hole transport agent is selected from combination No. 1 shown in Table 2. Each of E1 to E40 is preferred. For the same reason, the combination of the polyarylate resin, the fluororesin particles, and the hole transport agent is the combination No. shown in Table 2. Each of E1 to E40, and the charge generating agent is more preferably Y-type titanyl phthalocyanine.

The meanings of the terms in Tables 1 and 2 are as follows. "No." indicates "combination No.". "HTM" stands for "hole transport agent". "Resin" means "polyarylate resin". "Particles" indicates fluororesin particles. “PTFE-1” indicates PTFE particles having an average primary particle size of 3.5 μm or more and less than 5.0 μm. “PTFE-2” indicates PTFE particles having an average primary particle size of 0.1 μm or more and less than 1.0 μm. “PTFE-3” indicates PTFE particles having an average primary particle size of 1.0 μm or more and less than 3.5 μm. “PTFE-4” indicates PTFE particles having an average primary particle size of 5.0 μm or more and 12.0 μm or less.

(Conductive substrate)
The conductive substrate is not particularly limited as long as it can be used as the conductive substrate of the photoreceptor. At least the surface portion of the conductive substrate may be made of a conductive material. An example of the conductive substrate is a conductive substrate made of a conductive material. Another example of a conductive substrate is a conductive substrate coated with a material having electrical conductivity. Conductive materials 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 two or more of them may be used in combination (for example, as an alloy). Among these electrically conductive materials, aluminum and aluminum alloys are preferred because of good charge transfer from the photosensitive layer to the conductive substrate.

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. Moreover, 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 used for the intermediate layer (intermediate layer resin). The presence of the intermediate layer makes it possible to maintain an insulating state to the extent that leakage can be suppressed, and to smooth the flow of current generated when the photosensitive member is exposed to light, thereby suppressing an increase in resistance.

Examples of inorganic particles include 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. One of these inorganic particles may be used alone, or two or more thereof may be used in combination.

Examples of the intermediate layer resin are the same as the other binder resins contained in the photosensitive layer. In order to form the intermediate layer and the photosensitive layer satisfactorily, 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 examples of additives contained in the photosensitive layer.

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

A method for manufacturing a layered photoreceptor 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 sometimes referred to as a charge generation layer coating liquid) is prepared. A coating liquid for the charge generating layer is applied onto the conductive substrate. Next, at least part of the solvent contained in the applied charge-generating layer coating liquid is removed to form the charge-generating layer. The charge generating layer coating liquid contains, for example, a charge generating agent, a base resin, and a solvent. Such a charge generating layer coating liquid is prepared by dissolving or dispersing a charge generating agent and a base resin in a solvent. The charge generation layer coating liquid may further contain additives, if necessary.

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

A method for manufacturing a single layer photoreceptor includes a step of forming a single layer photoreceptor. In the single-layer type photosensitive layer forming step, a coating liquid for forming a single-layer type photosensitive layer (hereinafter sometimes referred to as a single-layer type photosensitive layer coating liquid) is prepared. A single-layer type photosensitive layer coating solution is applied onto a conductive substrate. Then, at least part of the solvent contained in the coated photosensitive layer coating liquid is removed to form a single layer type photosensitive layer. The single-layer photosensitive layer coating liquid contains, for example, a charge generating agent, a hole transporting agent, a binder resin, and a solvent. The single-layer photosensitive layer coating liquid is prepared by dissolving or dispersing a charge generating agent, a hole transporting agent, a binder resin, and fluororesin particles in a solvent. The single-layer type photosensitive layer coating solution may further contain an electron transport agent. The single-layer type photosensitive layer coating solution may further contain additives, if necessary.

The solvent contained in the single-layer photosensitive layer coating liquid, the charge generation layer coating liquid, and the charge transport layer coating liquid (hereinafter, these may be collectively referred to as coating liquids) There are no particular limitations as long as each component contained can be dissolved or dispersed. Examples of solvents include 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, chlorobenzene, etc.), ethers (more specifically, dimethyl ether , diethyl ether, tetrahydrofuran, ethylene glycol dimethyl ether, and diethylene glycol dimethyl ether), ketones (more specifically, acetone, methyl ethyl ketone, cyclohexanone, etc.), esters (more specifically, ethyl acetate, methyl acetate, etc.), Dimethylformaldehyde, dimethylformamide, and dimethylsulfoxide. These solvents may be used singly or in combination of two or more.

The solvent contained in the charge-transporting layer coating liquid is preferably different from the solvent contained in the charge-generating layer coating liquid. This is because when the charge-transporting layer coating liquid is applied onto the charge-generating layer, it is preferable that the charge-generating layer does not dissolve in the solvent of the charge-transporting layer coating liquid.

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

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

Methods for removing at least part of the solvent contained in the coating liquid include, for example, heating, reduced pressure, or combined use of heating and reduced pressure. More specifically, a method of heat-treating (hot-air drying) using a high-temperature dryer or a reduced-pressure dryer is exemplified. The heat treatment temperature 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.

Incidentally, the method for manufacturing a photoreceptor 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.

EXAMPLES Hereinafter, the present invention will be described more specifically using examples. However, the present invention is in no way limited to the scope of the examples.

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

<Preparation of filler particles>
As filler particles, filler particles (F1) to (F7) shown below were prepared. The filler particles (F1) to (F4) were fluororesin particles.
Filler particles (F1): PTFE particles, average primary particle size 3.5 μm, manufactured by Daikin Industries, Ltd. “Lubron (registered trademark) L-2”
Filler particles (F2): PTFE particles, average primary particle size 0.6 μm, "KTL-500F" manufactured by Kitamura Co., Ltd.
Filler particles (F3): PTFE particles, average primary particle size 3.0 μm, manufactured by Kitamura Co., Ltd. “KTL-1N”
Filler particles (F4): PTFE particles, average primary particle size 10.0 μm, "KTL-10N" manufactured by Kitamura Co., Ltd.
Filler particles (F5): Hydrophobic fumed silica particles, average primary particle size 0.007 μm, “AEROSIL (registered trademark) RX300” manufactured by Nippon Aerosil Co., Ltd.
Filler particles (F6): Silica particles surface-treated with hexamethyldisilazane, average primary particle size 0.014 μm, “AEROSIL (registered trademark) RX200” manufactured by Nippon Aerosil Co., Ltd.
Filler particles (F7): Hydrophobic fumed silica particles, average primary particle size 0.095 μm, “VPRX40s” manufactured by Nippon Aerosil Co., Ltd.

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

(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 a reaction vessel. A reaction vessel was charged with 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 charged. 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 compound (DC-3) dicarboxylic acid dichloride (32.4 mmol) was dissolved in chloroform (150 mL). A chloroform solution B was thus obtained.

Using a dropping funnel, the chloroform solution B was slowly added dropwise to the alkaline aqueous solution A over 110 minutes. 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 allow the polymerization reaction to proceed. The upper layer (aqueous layer) of the contents of the reaction vessel was removed using decanting to obtain an organic layer. Then, ion-exchanged water (400 mL) was added to the Erlenmeyer flask. The resulting 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 decanting to obtain an organic layer. Using a separating funnel, the obtained organic layer was washed with ion-exchanged water (1 L). 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 resulting filtrate was slowly added dropwise to methanol (1 L) to obtain a precipitate. The precipitate was removed by filtration. The sediment taken out was vacuum-dried at a temperature of 70° C. for 12 hours. Thus, a polyarylate resin (R-1) was obtained.

(Synthesis of polyarylate resin (R-2))
In the same manner as in the synthesis of polyarylate resin (R-1), 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))
In the same manner as in the synthesis of the 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))
In the same manner as in the synthesis of the 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))
In the same manner as in the synthesis of the 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 polyarylate resin (R-6) was obtained in the same manner as the synthesis of the polyarylate resin (R-1), except that it 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, 50,500, 51,000, 45,000, 47,300, 45,500 and 48,700.

Using a proton nuclear magnetic resonance spectrometer (manufactured by JASCO Corporation, 300 MHz), ¹ H-NMR spectra of the obtained polyarylate resins (R-1) to (R-6) were measured. CDCl ₃ was used as solvent. Tetramethylsilane (TMS) was used as an internal standard sample. As a representative example of the polyarylate resins (R-1) to (R-6), the chemical shift value of the polyarylate resin (R-6) is shown below. It was confirmed from the chemical shift value that a polyarylate resin (R-6) was obtained. Polyarylate resins (R-1) to (R-5) were confirmed by the same method to be obtained respectively.

Polyarylate resin (R-6): 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>
Also, polyarylate resins (RA) to (RG) were prepared as polyarylate resins used in comparative examples. 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), percentage of the number of repeating units (3) with respect 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 10.0%.

The polyarylate resin (RE) 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 number of repeating units (DC-I) are 50.0%, 25.0%, 15.0%, and 10.0%, respectively.

The polyarylate resin (RF) 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 number of repeating units (DC-I) are 50.0%, 25.0%, 15.0%, and 10.0%, respectively.

The polyarylate resin (RG) contains only the following repeating unit (BP-Z) as a bisphenol-derived repeating unit. 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 number of repeating units (DC-I) are 50.0%, 25.0%, 15.0%, and 10.0%, respectively.

Incidentally, the viscosity average molecular weights 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.

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

<Production of laminated photoreceptor>
Next, layered photoreceptors (A-1) to (A-19) and (B-1) to (B-11) were produced by the following method.

(Production of laminated photoreceptor (A-1))
First, an intermediate layer was formed. A surface-treated titanium oxide (“Prototype SMT-A” manufactured by Tayca Co., Ltd., number average primary particle diameter 10 nm) was prepared. SMT-A was obtained by surface-treating titanium oxide with alumina and silica, and further surface-treating it with methylhydrogenpolysiloxane while dispersing the surface-treated titanium oxide in a wet process. Next, 2 parts by mass of SMT-A, and 1 part by mass of a polyamide resin ("Amilan (registered trademark) CM8000" manufactured by Toray Industries, Inc., a quaternary copolymerized polyamide resin of polyamide 6, polyamide 12, polyamide 66 and polyamide 610) , 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 an intermediate layer coating liquid. The intermediate layer coating liquid was filtered using a filter with an opening of 5 μm. Thereafter, the intermediate layer coating liquid was applied to the surface of the conductive substrate by a dip coating method. A drum-like support made of aluminum was used as the conductive substrate. Subsequently, the applied intermediate layer coating liquid 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 phthalocyanine as a charge generating agent, 1.0 parts by mass of polyvinyl acetal resin (“S-Lec BX-5” manufactured by Sekisui Chemical Co., Ltd.) as a base resin, and 1.0 part by mass of propylene glycol monomethyl 40.0 parts by mass of ether and 40.0 parts by mass of tetrahydrofuran were mixed for 12 hours using a bead mill to obtain a charge generation layer coating liquid. The charge generation layer coating liquid was filtered using a filter with an opening of 3 μm. The resulting filtrate was applied onto the intermediate layer by dip coating and dried at 50° C. for 5 minutes. Thus, a charge generating layer (thickness: 0.3 μm) was formed on the intermediate layer.

Next, a charge transport layer was formed. Specifically, 45 parts by mass of compound (HTM-1) as a hole transport agent, 100 parts by mass of polyarylate resin (R-1) as binder resin, 6 parts by mass of filler particles (F1), and 550 parts by mass of tetrahydrofuran and 150 parts by mass of toluene were mixed for 12 hours using a circulating ultrasonic dispersing device to obtain a coating liquid for charge transport layer. The charge transport layer coating liquid was applied onto the charge generation layer by dip coating and dried at 120° C. for 40 minutes. Thus, a charge transport layer (thickness: 20 μm) was formed on the charge generation layer to obtain a laminated photoreceptor (A-1). In the laminated photoreceptor (A-1), the intermediate layer was provided on the conductive substrate, the charge generation layer was provided on the intermediate layer, and the charge transport layer was provided on the charge generation layer.

(Production of laminated photoreceptors (A-2) to (A-17) and (B-1) to (B-10))
Layered photoreceptor (A -2) to (A-17) and (B-1) to (B-10) were each produced.

(Production of laminated photoreceptors (A-18) to (A-19) and (B-11))
A layered photoreceptor (A-18) was produced in the same manner as the layered photoreceptor (A-1) except that the amount of filler particles (F1) added was changed from 6 parts by mass to 3 parts by mass. bottom. A layered photoreceptor (A-19) was produced in the same manner as the layered photoreceptor (A-1) except that the amount of filler particles (F1) added was changed from 6 parts by mass to 11 parts by mass. bottom. A layered photoreceptor (B-11) was produced in the same manner as the layered photoreceptor (A-1), except that the filler particles (F1) were not added.

<Evaluation>
The laminated photoreceptors (A-1) to (A-19) and (B-1) to (B-11), which are photoreceptors to be evaluated, were evaluated by the following methods.

<Abrasion resistance evaluation>
A color printer (“C542dnw” manufactured by Oki Data Co., Ltd.) was used as an evaluation machine for evaluating abrasion resistance. Cyan toner was filled in the toner cartridge of the evaluation machine. First, the film thickness T1 of the photosensitive layer (specifically, the charge transport layer) of the photoreceptor was measured. The photoreceptor was then mounted on the evaluation machine. Next, under an environment of a temperature of 23° C. and a relative humidity of 50% RH, an image I (pattern image with a print rate of 1%) was printed on 300,000 sheets of paper using the evaluation machine. After printing 300,000 sheets, the film thickness T2 of the photosensitive layer of the photoreceptor was measured. Then, the amount of wear (T1-T2, unit: μm), which is the change in thickness of the photosensitive layer before and after printing, was determined. Tables 4 and 5 show the amount of wear. From the amount of abrasion, the abrasion resistance of the photoreceptor was evaluated according to the following criteria.
[Abrasion resistance evaluation criteria]
Good: Wear amount is 3.0 μm or less.
Poor: The amount of wear exceeds 3.0 μm.

<Evaluation of blade turning>
After completing the above <evaluation of wear resistance>, the evaluation machine was moved to a high-temperature and high-humidity environment (temperature of 32.5°C and relative humidity of 85%). Image II (an image with a print rate of 70%) was printed on 10,000 sheets of paper using the evaluation machine under a high-temperature, high-humidity environment. After printing, it was confirmed whether or not the cleaning blade was turned over. Confirmation results are shown in Tables 4 and 5.

<Evaluation of Dynamic Friction Coefficient of Surface of Photoreceptor>
Before (before printing) and after (after printing) the <evaluation of abrasion resistance> and the <evaluation of blade turning>, the dynamic friction coefficient of the surface of the photoreceptor was measured. First, the dynamic friction coefficient of the surface of the photoreceptor before printing was measured by the following method. A nonwoven fabric (“Kimwipe S-200” manufactured by Nippon Paper Crecia Co., Ltd.) was placed on the surface (surrounding surface) of the photoreceptor, and a weight (load: 200 gf) was placed on the nonwoven fabric. The contact area between the weight and the surface of the photoreceptor via the nonwoven fabric was 1 cm ² . While fixing the weight, the photoreceptor was slid sideways at a speed of 50 mm/sec. A load cell was used to measure the lateral frictional force when sliding sideways. The dynamic friction coefficient (μ1) of the surface of the photoreceptor before printing was calculated from the formula “dynamic friction coefficient=measured lateral friction force/200”. Next, the dynamic friction coefficient (μ2) of the surface of the photoreceptor after printing was measured in the same manner as the measurement of the dynamic friction coefficient of the surface of the photoreceptor before printing. Tables 4 and 5 show the dynamic friction coefficients. The surface properties of the photoreceptor were evaluated according to the following criteria from the coefficients of dynamic friction (μ1 and μ2).
[Evaluation Criteria for Surface Characteristics of Photoreceptor]
Good: Dynamic friction coefficient is 0.60 or less.
Poor: Dynamic friction coefficient is over 0.60.

The better the evaluation of the surface characteristics of the photoreceptor and the smaller the difference in the dynamic friction coefficient before and after printing (μ2−μ1), the less likely the dynamic friction coefficient of the photoreceptor will change due to printing, and the better the surface characteristics of the photoreceptor will be. It shows that it is good.

Terms in Tables 4 and 5 are as follows. "HTM" indicates hole transport agent. "Resin" refers to polyarylate resin. "Filler" refers to filler particles. The "amount" of "filler" indicates the content of filler particles (unit: % by mass) with respect to the mass of the binder resin. The content of the filler particles was calculated from the formula "filler particle content=100×filler particle amount (unit: parts by mass)/binder resin amount (unit: parts by mass)". "None" in "Blade turn-up" indicates that no blade turn-up occurred, and "Occurred" indicates that blade turn-up occurred. "Coefficient of friction" indicates the coefficient of dynamic friction. In the "coefficient of friction", "μ1" indicates the dynamic friction coefficient of the surface of the photoreceptor before printing, "μ2" indicates the dynamic friction coefficient of the surface of the photoreceptor after printing, and "difference" indicates the surface of the photoreceptor before and after printing. shows the difference in dynamic friction coefficient (μ2-μ1). "Not dissolved" indicates that the binder resin was not dissolved in the solvent during the preparation of the charge transport layer coating liquid, and the charge transport layer could not be formed.

As shown in Table 4, the photosensitive layers (more specifically, charge transport layers) of the layered photoreceptors (A-1) to (A-19) are each a hole transport agent and a binder resin. Polyarylate resin (more specifically, any of polyarylate resins (R-1) to (R-6)) and fluororesin particles (more specifically, filler particles (F1) to (F4) whichever). As shown in Table 3, the polyarylate resins (R-1) to (R-6) contain repeating units (1), repeating units (2), and repeating units (3). The ratio n ₁ / _{n 2 of the number n 1 of} repeating units (1) to the number n ₂ of repeating units (1) was 1.0 or more.

As shown in Table 4, the abrasion amount of the laminated photoreceptors (A-1) to (A-19) is 3.0 μm or less, and the laminated photoreceptors (A-1) to (A-19) Excellent abrasion resistance. Further, the dynamic friction coefficient μ1 before printing and the dynamic friction coefficient μ2 after printing on the surfaces of the layered photoreceptors (A-1) to (A-19) were all 0.60 or less. Since the dynamic friction coefficients μ1 and μ2 were obtained, blade curling did not occur in the layered photoreceptors (A-1) to (A-19).

From the above, it was shown that the photoreceptor according to the present invention is excellent in wear resistance and can suppress the occurrence of blade curling.

A photoreceptor according to the present invention can be used in an image forming apparatus.

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

Claims (8)

comprising a conductive substrate and a photosensitive layer;
The photosensitive layer contains a charge generating agent, a hole transporting agent, a binder resin, and fluororesin particles,
The binder resin includes a polyarylate resin, and the polyarylate resin includes repeating units represented by general formula (1), repeating units represented by chemical formula (2), and 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 the chemical formula (2) is 1. is 0 or more,
The electrophotographic photoreceptor, wherein the hole transport agent contains a compound represented by general formula (20), general formula (21), or general formula (22).

(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, or
R ¹ and R ² each represent a methyl group, and R ³ and R ⁴ are combined to represent a cycloalkylidene group having 5 or 6 carbon atoms. )

(In general formula (20), R ²¹ and R ²² 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, and R ²³ and R ²⁴ are each independently a phenyl group optionally substituted with an alkyl group having 1 to 8 carbon atoms, a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, or 1 to 8 carbon atoms. and R ²⁵ , R ²⁶ , R ²⁷ , R ²⁸ and R ²⁹ are each independently a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, a phenyl group, or 1 or more carbon atoms represents an alkoxy group of 8 or less, and adjacent two of R 25 , R 26 , R 27 , ^R 28 ^and R ²⁹ may ^combine to ^represent a ring, and a1 and a2 are each independently 0 Represents an integer greater than or equal to 5 or less,
In general formula (21), R ³¹ to R ³⁶ each independently represent an alkyl group having 1 to 8 carbon atoms or a phenyl group; R ³⁷ and R ³⁸ each independently represent a hydrogen atom; represents 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 to 5; b5 and b6 each independently represent 0 represents an integer of 4 or less, 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 to 8 carbon atoms, a phenyl group, or an alkoxy group having 1 to 8 carbon atoms; , f4, and f5 each independently represent an integer of 0 to 5, and f3 and f6 each independently represent an integer of 0 to 4. ) The repeating unit represented by the general formula (1) is represented by chemical formula (1-1), chemical formula (1-2), chemical formula (1-3), chemical formula (1-4), or chemical formula (1-5). 2. The electrophotographic photoreceptor of claim 1, which is a repeating unit represented by:

3. The electrophotographic photoreceptor according to claim 1, wherein the fluororesin particles have an average primary particle size of 0.1 [mu]m to 12.0 [mu]m. 4. The electrophotographic photoreceptor according to claim 1, wherein the content of the fluororesin particles is 3% by mass or more and 11% by mass or less with respect to the mass of the binder resin. 5. The electrophotographic photoreceptor according to claim 1, wherein the fluororesin particles are polytetrafluoroethylene particles. The hole transport agent has chemical formula (HTM-1), chemical formula (HTM-2), chemical formula (HTM-3), chemical formula (HTM-4), chemical formula (HTM-5), chemical formula (HTM-6), chemical formula 6. The electrophotographic photoreceptor according to claim 1 , comprising a compound represented by (HTM-7), chemical formula (HTM-8), or chemical formula (HTM-9).

The electrophotographic photoreceptor according to any one of claims 1 to 6 , wherein the photosensitive layer is provided as an outermost layer. The photosensitive layer includes a charge generation layer containing the charge generation agent, and a charge transport layer containing the hole transport agent, the binder resin, and the fluororesin particles,
The electrophotographic photoreceptor according to any one of claims 1 to 7 , wherein the charge transport layer is a single layer and provided as the outermost layer.

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