JP7215577B2 - Electrophotographic photoreceptor, process cartridge, and image forming apparatus - 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 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.

The electrophotographic photoreceptor included in the image forming apparatus described in Patent Document 1 contains a bisphenol Z-type polycarbonate resin as a binder resin at least in its surface layer.

JP-A-8-234538

However, a study by the present inventors revealed that the electrophotographic photoreceptor included in the image forming apparatus described in Patent Document 1 is insufficient in abrasion resistance and charging stability.

SUMMARY OF THE INVENTION An object of the present invention is to provide an electrophotographic photoreceptor that is excellent in abrasion resistance and charging stability. Another object of the present invention is to provide a process cartridge and an image forming apparatus which are equipped with such an electrophotographic photoreceptor and which are excellent in durability and capable of forming good images.

The electrophotographic photoreceptor of the present invention comprises 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, a binder resin, and an n-type pigment. The binder resin includes polyarylate resin. The polyarylate resin contains at least one type of repeating unit represented by general formula (1) and at least one type of repeating unit represented by general formula (2).

In general formula (1), a represents 1 or 2; In general formula (2), X represents a divalent group represented by chemical formula (X1), (X2), (X3), (X4), or (X5).

A process cartridge of the present invention includes the above electrophotographic photosensitive member.

An 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 image carrier is rotatably provided. The charging device positively charges the surface of the image carrier. The exposure device irradiates the charged surface of the image carrier with light to form an electrostatic latent image on the surface of the image carrier. The developing device develops the electrostatic latent image into a toner image. The transfer device transfers the toner image from the image bearing member to a transfer receiving member. The image carrier is the electrophotographic photoreceptor.

The electrophotographic photoreceptor of the present invention is excellent in abrasion resistance and charge stability. Further, the process cartridge and the image forming apparatus of the present invention equipped with such an electrophotographic photoreceptor are excellent in durability and can form good images.

1 is a partial cross-sectional view of an electrophotographic photoreceptor according to an embodiment of the present invention; FIG. 1 is a partial cross-sectional view of an electrophotographic photoreceptor according to an embodiment of the present invention; FIG. 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; 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. Halogen atoms (halogen groups) include, for example, fluorine atoms (fluoro groups), chlorine atoms (chloro groups), bromine atoms (bromo groups), and iodine atoms (iodo groups).

an alkyl group having 1 to 10 carbon atoms, an alkyl group having 1 to 8 carbon atoms, an alkyl group having 1 to 6 carbon atoms, an alkyl group having 1 to 5 carbon atoms, and an alkyl group having 1 to 4 carbon atoms Each of the following alkyl groups and alkyl groups having 1 to 3 carbon atoms is linear or branched and unsubstituted, unless otherwise specified. Examples of alkyl groups having 1 to 10 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, linear and branched heptyl, linear and branched octyl, linear and branched Nonyl groups in the form of chains and decyl groups in the form of straight and branched chains are included. an alkyl group having 1 to 8 carbon atoms, an alkyl group having 1 to 6 carbon atoms, an alkyl group having 1 to 5 carbon atoms, an alkyl group having 1 to 4 carbon atoms, and an alkyl group having 1 to 4 carbon atoms; Examples of alkyl groups of 3 or less are groups having the corresponding number of carbon atoms among the groups described as examples of alkyl groups having 1 to 10 carbon atoms.

An alkoxy group having 1 to 8 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, and an alkoxy group having 1 to 3 carbon atoms are each unless otherwise specified. are straight-chain or branched and unsubstituted as long as they are Examples of alkoxy groups having 1 to 6 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 an alkoxy group having 1 to 6 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, and an alkoxy group having 1 to 3 carbon atoms are each an alkoxy group having 1 to 8 carbon atoms. Of the groups mentioned as examples, these are groups having the corresponding number of carbon atoms.

Aryl groups, aryl groups having 6 to 14 carbon atoms, and aryl groups having 6 to 10 carbon atoms are each unsubstituted unless otherwise specified. The aryl group is, for example, an aryl group having 6 or more and 14 or less carbon atoms. Examples of aryl groups having 6 to 14 carbon atoms include phenyl, naphthyl, indacenyl, biphenylenyl, acenaphthylenyl, anthryl and phenanthryl groups. Examples of the aryl group having 6 to 10 carbon atoms include a phenyl group and a naphthyl group.

Aryloxy groups having 6 to 14 carbon atoms are unsubstituted unless otherwise specified. Examples of aryloxy groups having 6 to 14 carbon atoms include phenoxy, naphthoxy, indacenyloxy, biphenylenyloxy, acenaphthylenyloxy, anthryloxy, and phenanthryloxy. and fluorenyloxy groups.

Unless otherwise specified, alkenyl groups having 2 to 6 carbon atoms are straight or branched and unsubstituted. The alkenyl group having 2 to 6 carbon atoms has 1 to 3 double bonds. Examples of alkenyl groups having 2 to 6 carbon atoms include ethenyl, propenyl, butenyl, butadienyl, pentenyl, hexenyl, hexadienyl, and hexatrinyl groups.

Each heterocyclic group and heterocyclic group having 3 to 14 carbon atoms is unsubstituted unless otherwise specified. The heterocyclic group is, for example, a heterocyclic group having 3 or more and 14 or less carbon atoms. Examples of heterocyclic groups having 3 to 14 carbon atoms include piperidinyl, piperazinyl, morpholinyl, thiophenyl, furanyl, pyrrolyl, imidazolyl, pyrazolyl, isothiazolyl, isoxazolyl, oxazolyl, and isoxazolyl. group, thiazolyl group, isothiazolyl group, furazanyl group, pyranyl group, pyridyl group, pyridazinyl group, pyrimidinyl group, pyrazinyl group, indolyl group, 1H-indazolyl group, isoindolyl group, chromenyl group, quinolinyl group, isoquinolinyl group, purinyl group, pteridinyl group, triazolyl group, tetrazolyl group, 4H-quinolidinyl group, naphthyridinyl group, benzofuranyl group, 1,3-benzodioxolyl group, benzoxazolyl group, benzothiazolyl group, benzimidazolyl group, carbazolyl group, phenanthridinyl group , acridinyl, phenazinyl, and phenanthrolinyl groups.

Aralkyl groups, aralkyl groups having 7 to 20 carbon atoms, and aralkyl groups having 7 to 12 carbon atoms are each unsubstituted unless otherwise specified. The aralkyl group is, for example, an aralkyl group having 7 or more and 20 or less carbon atoms. The aralkyl group having 7 to 20 carbon atoms is, for example, an alkyl group having 1 to 6 carbon atoms substituted with an aryl group having 6 to 14 carbon atoms. The aralkyl group having 7 to 12 carbon atoms is, for example, an alkyl group having 1 to 6 carbon atoms and substituted with a phenyl group.

An aralkyloxy group having 7 to 20 carbon atoms and an aralkyloxy group having 7 to 10 carbon atoms are each unsubstituted unless otherwise specified. The aralkyloxy group having 7 to 20 carbon atoms is, for example, an alkoxy group having 1 to 6 carbon atoms substituted with an aryl group having 6 to 14 carbon atoms. The aralkyl group having 7 to 10 carbon atoms is, for example, an alkoxy group having 1 to 4 carbon atoms and substituted with a phenyl group. 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 structure of the photoreceptor 1 of this embodiment will be described below with reference to FIGS. 1 to 3. FIG. 1 to 3 each show a partial cross-sectional view of photoreceptor 1. FIG.

As shown in FIG. 1, the photoreceptor 1 includes, for example, a conductive substrate 2 and a photosensitive layer 3. As shown in FIG. The photosensitive layer 3 is a single layer. The photoreceptor 1 is a single layer electrophotographic photoreceptor having a single photosensitive 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). An intermediate layer 4 is provided between the conductive substrate 2 and the photosensitive layer 3 . The photosensitive layer 3 may be provided directly on the conductive substrate 2, as shown in FIG. 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 comprise a conductive substrate 2, a photosensitive layer 3, and a protective layer 5. As shown in FIG. A protective layer 5 is provided on the photosensitive layer 3 . As shown in FIGS. 1 and 2, a photosensitive layer 3 may be provided as the outermost layer of the photoreceptor 1 . Alternatively, as shown in FIG. 3, a protective layer 5 may be provided as the outermost surface layer of the photoreceptor 1 .

The photosensitive layer 3 contains a charge generating agent, a hole transporting agent, an electron transporting agent, a binder resin, and an n-type pigment.

Although the thickness of the photosensitive layer 3 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 structure of the photoreceptor 1 has been described above with reference to FIGS. 1 to 3. FIG. The photoreceptor will be further described below.

(binder resin)
The photosensitive layer contains a polyarylate resin as a binder resin. The polyarylate resin contains at least one type of repeating unit represented by general formula (1) and at least one type of repeating unit represented by general formula (2). Hereinafter, a polyarylate resin containing at least one repeating unit represented by the general formula (1) and at least one repeating unit represented by the general formula (2) is referred to as a polyarylate resin (PA). I have something to do. Also, the repeating units represented by formulas (1) and (2) are sometimes referred to as repeating units (1) and (2), respectively.

In general formula (1), a represents 1 or 2; In general formula (2), X represents a divalent group represented by chemical formula (X1), (X2), (X3), (X4), or (X5).

Polyarylate resin (PA) has a given chemical structure. By containing such a polyarylate resin (PA) in the photosensitive layer, the wear resistance of the photosensitive member can be improved. Moreover, since the polyarylate resin (PA) has a predetermined chemical structure, the density of the photosensitive layer can be increased. Therefore, it becomes difficult for a substance (for example, gas) that lowers the charging potential to enter the photosensitive layer, and the charging stability of the photosensitive member is improved. In this specification, the charge stability of the photoreceptor means a property that the charge potential of the photoreceptor does not easily decrease even when images are repeatedly printed using an image forming apparatus having the photoreceptor.

In general formula (1), a preferably represents 2. In general formula (2), X preferably represents a divalent group represented by chemical formula (X1), (X3), (X4), or (X5).

Preferable examples of repeating unit (1) include repeating units represented by chemical formulas (1-1) and (1-2). Hereinafter, repeating units represented by chemical formulas (1-1) and (1-2) may be referred to as repeating units (1-1) and (1-2), respectively.

Preferred examples of the repeating unit (2) include repeating units represented by chemical formulas (2-X1), (2-X2), (2-X3), (2-X4), and (2-X5). mentioned. Hereinafter, the repeating units represented by the chemical formulas (2-X1), (2-X2), (2-X3), (2-X4), and (2-X5) are each replaced with the repeating unit (2-X1) , (2-X2), (2-X3), (2-X4), and (2-X5). More preferred examples of repeating unit (2) include repeating units (2-X1), (2-X3), (2-X4), and (2-X5).

An example of the polyarylate resin (PA) is a polyarylate resin containing repeating units (1-2) and (2-X3) (hereinafter referred to as polyarylate resin (V)). As the polyarylate resin (V), a polyarylate resin containing only repeating units (1-2) and (2-X3) as repeating units (hereinafter referred to as polyarylate resin (V')) is preferable.

Another example of the polyarylate resin (PA) is a polyarylate resin containing repeating units (1-2) and (2-X5) (hereinafter referred to as polyarylate resin (IX)). As the polyarylate resin (IX), a polyarylate resin containing only repeating units (1-2) and (2-X5) as repeating units (hereinafter referred to as polyarylate resin (IX')) is preferable.

Still another example of the polyarylate resin (PA) is a polyarylate resin containing repeating units (1-2), (2-X1), and (2-X4) (hereinafter referred to as polyarylate resin (I) ).

Still another example of the polyarylate resin (PA) is a polyarylate resin containing repeating units (1-2), (2-X1), and (2-X3) (hereinafter referred to as polyarylate resin (II) ). As the polyarylate resin (II), a polyarylate resin containing only repeating units (1-2), (2-X1), and (2-X3) as repeating units (hereinafter referred to as polyarylate resin (II') described) is preferred.

Yet another example of the polyarylate resin (PA) is a polyarylate resin containing repeating units (1-2), (2-X4), and (2-X3) (hereinafter referred to as polyarylate resin (III) ).

Still another example of the polyarylate resin (PA) is a polyarylate resin containing repeating units (1-2), (2-X5), and (2-X3) (hereinafter referred to as polyarylate resin (VIII) ).

Still another example of the polyarylate resin (PA) is a polyarylate resin containing repeating units (1-2), (2-X5), and (2-X1) (hereinafter referred to as polyarylate resin (VI) ).

Still another example of the polyarylate resin (PA) is a polyarylate resin containing repeating units (1-1), (2-X1), and (2-X3) (hereinafter referred to as polyarylate resin (X) ).

Still another example of the polyarylate resin (PA) is a polyarylate resin containing repeating units (1-1), (1-2), (2-X1), and (2-X3) (hereinafter referred to as polyarylate resin (XII)).

Preferable examples of the polyarylate resin (PA) include polyarylate resins represented by chemical formulas (R1) to (R12) (hereinafter each may be referred to as polyarylate resins (R1) to (R12)). is mentioned. In the chemical formulas (R1) to (R12), 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 total number of repeating units contained in the polyarylate resin is the sum of the number of bisphenol-derived repeating units and the number of dicarboxylic acid-derived repeating units.

The polyarylate resin (PA) contains one or two repeating units (1). When the polyarylate resin (PA) contains two types of repeating units (1), the ratio of the number of one repeating unit (1) to the total number of one repeating unit (1) and the other repeating unit (1) is preferably 10% or more and 90% or less, more preferably 30% or more and 70% or less, even more preferably 40% or more and 60% or less, and 55% or more and 60% or less. Especially preferred. When the two types of repeating units (1) are repeating units (1-1) and (1-2), one repeating unit (1) is repeating unit (1-2) and the other repeating unit (1 ) is the repeating unit (1-1).

The polyarylate resin (PA) contains one to five repeating units (2). The polyarylate resin (PA) preferably contains at least two types (for example, two to five types) of repeating units (2), more preferably two types of repeating units (2). When the polyarylate resin (PA) contains two types of repeating units (2), the ratio of the number of one repeating unit (2) to the total number of one repeating unit (2) and the other repeating unit (2) is preferably 10% or more and 90% or less, more preferably 30% or more and 80% or less, further preferably 50% or more and 80% or less, and 50% or more and 70% or less Especially preferred. When the two repeating units (2) are the repeating units (2-X3) and (2-X4), one repeating unit (2) is the repeating unit (2-X3) and the other repeating unit (2 ) is the repeating unit (2-X4). When the two types of repeating units (2) are repeating units (2-X1) and (2-X3), one repeating unit (2) is repeating unit (2-X3) and the other repeating unit (2 ) is the repeating unit (2-X1).

The number ratio of the one repeating unit (1) and the number ratio of the one repeating unit (2) are obtained by analyzing the ¹ H-NMR spectrum of the polyarylate resin (PA) using a proton nuclear magnetic resonance spectrometer. It can be obtained by measuring and calculating the ratio of peaks characteristic of each repeating unit in the obtained ¹ H-NMR spectrum.

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

In the polyarylate resin (PA), the bisphenol-derived repeating unit and the dicarboxylic acid-derived repeating unit are adjacently bonded to each other. A bisphenol-derived repeating unit is, for example, repeating unit (1). Further, the dicarboxylic acid-derived repeating unit is, for example, the repeating unit (2). Polyarylate resins (PA) can be, for example, random copolymers, alternating copolymers, periodic copolymers, or block copolymers.

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 more preferable, and 50,000 or more 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.

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

Examples of bisphenols constituting the bisphenol repeating unit include compounds represented by general formula (BP-1). Examples of the dicarboxylic acid constituting the dicarboxylic acid repeating unit include compounds represented by general formula (DC-2). a in general formula (BP-1) has the same meaning as a in general formula (1). X in general formula (DC-2) has the same definition as X in general formula (2).

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. In addition to the polyarylate resin (PA), the photosensitive layer may further contain a binder resin other than the polyarylate resin (PA) (hereinafter referred to as other 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, and polyether resins), thermosetting resins (more specifically, silicone resins, epoxy resins, phenolic resins, urea resins , melamine resins, and other crosslinkable thermosetting resins), and photocurable resins (more specifically, epoxy-acrylic acid-based resins and urethane-acrylic acid-based copolymers).

(n-type pigment)
An n-type pigment is a pigment in which the primary charge carriers are electrons. A p-type pigment is a pigment whose main charge carrier is a hole. By containing the n-type pigment in the photosensitive layer, the dispersibility of the charge generating agent in the photosensitive layer is improved, and a uniform photosensitive layer can be formed. Therefore, the charging stability of the photoreceptor can be improved. When the photosensitive layer contains the n-type pigment and the polyarylate resin (PA), the charge stability of the photoreceptor is significantly improved. Examples of n-type pigments include azo pigments and perylene pigments.

Azo pigments, which are examples of n-type pigments, will be described below. Azo pigments have an azo group (-N=N-). Azo pigments include, for example, monoazo pigments and polyazo pigments (eg, bisazo pigments, trisazo pigments, and tetrakisazo pigments). Azo pigments may be tautomers. Also, the azo pigment may have a chlorine atom (chloro group) in addition to the azo group.

Examples of azo pigments include known azo pigments. Suitable examples of azo pigments include pigment yellow (14, 17, 49, 65, 73, 83, 93, 94, 95, 128, 166, and 77), pigment orange (1, 2, 13, 34, and 36), and Pigment Reds (30, 32, 61, and 144).

More preferred examples of the azo pigment include the azo pigment (Pigment Yellow 128) represented by the chemical formula (A1), the azo pigment (Pigment Yellow 93) represented by the chemical formula (A2), and the azo pigment represented by the chemical formula (A3). Examples include an azo pigment (Pigment Orange 13) and an azo pigment (Pigment Yellow 83) represented by the chemical formula (A4). Hereinafter, the azo pigments represented by the chemical formulas (A1), (A2), (A3), and (A4) are referred to as azo pigments (A1), (A2), (A3), and (A4), respectively. Sometimes.

Next, a perylene pigment, which is an example of the n-type pigment, will be described. A perylene pigment has a perylene skeleton represented by general formula (PI). In general formula (PI), Q ⁴⁰ and Q ⁴¹ each independently represent a divalent organic group.

A first specific example of the perylene pigment is a perylene pigment represented by general formula (P-II).

In general formula (P-II), Q ⁴² and Q ⁴³ each independently represent a hydrogen atom or a monovalent organic group. Z ¹ and Z ² each independently represent an oxygen atom or a nitrogen atom.

In general formula (P-II), the monovalent organic groups represented by Q ⁴² and Q ⁴³ include aliphatic hydrocarbon groups, alkoxy groups, optionally substituted aralkyl groups, optionally substituted aryl groups, and An optionally substituted heterocyclic group is included.

In general formula (P-II), the aliphatic hydrocarbon groups represented by Q ⁴² and Q ⁴³ may be linear, branched, cyclic, or a combination thereof. The aliphatic hydrocarbon group may be saturated or unsaturated, preferably saturated. In general formula (P-II), the aliphatic hydrocarbon group represented by Q ⁴² and Q ⁴³ is preferably an aliphatic hydrocarbon group having 1 to 20 carbon atoms, and an aliphatic hydrocarbon group having 1 to 10 carbon atoms. A hydrocarbon group is more preferred. The aliphatic hydrocarbon group having 1 to 10 carbon atoms is preferably an alkyl group having 1 to 10 carbon atoms, more preferably an alkyl group having 1 to 6 carbon atoms, and 1 to 3 carbon atoms. is more preferred, and a methyl group or an ethyl group is particularly preferred.

In general formula (P-II), the alkoxy group represented by Q ⁴² and Q ⁴³ is preferably an alkoxy group having 1 to 6 carbon atoms, more preferably an alkoxy group having 1 to 3 carbon atoms, and a methoxy group. or an ethoxy group is more preferred.

In general formula (P-II), the aralkyl group represented by Q ⁴² and Q ⁴³ is preferably an aralkyl group having 7 to 12 carbon atoms, such as benzyl group, phenethyl group, α-naphthylmethyl group, or β-naphthyl. A methyl group is more preferred, and a benzyl group or a phenethyl group is even more preferred.

In general formula (P-II), the aryl group represented by Q ⁴² and Q ⁴³ is preferably an aryl group having 6 to 14 carbon atoms, more preferably an aryl group having 6 to 10 carbon atoms, and a phenyl group. is more preferred.

In general formula (P-II), the heterocyclic group represented by Q ⁴² and Q ⁴³ is preferably a heterocyclic group having 3 or more and 14 or less carbon atoms, and a heterocyclic group having 3 or more and 14 or less carbon atoms having a nitrogen atom as a heteroatom. is more preferred, and a pyridyl group is even more preferred.

In general formula (P-II), the aralkyl group, aryl group and heterocyclic group represented by Q ⁴² and Q ⁴³ may be substituted with a substituent. As such a substituent, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, a phenyl group, a halogen atom, a hydroxy group, a cyano group, a nitro group, or a phenylazo group is preferable. , an alkyl group having 1 to 6 carbon atoms (eg, methyl group), a halogen atom (eg, chlorine atom), or a phenylazo group is more preferable.

In general formula (P-II), Q ⁴² and Q ⁴³ are alkyl groups having 1 to 6 carbon atoms; heterocyclic groups having 3 to 14 carbon atoms; aralkyl groups having 7 to 12 carbon atoms; an alkoxy group having 1 to 6 carbon atoms; an aryl group having 6 to 14 carbon atoms optionally substituted by an alkyl group having 1 to 6 carbon atoms, a halogen atom, or a phenylazo group; or a hydrogen atom is preferably represented. In general formula (P-II), Q ⁴² and Q ⁴³ each represent a methyl group, ethyl group, pyridyl group, benzyl group, phenylethyl group, ethoxy group, methoxy group, phenyl group, dimethylphenyl group (more preferably 3 , 5-dimethylphenyl group), a chlorophenyl group (more preferably a 4-chlorophenyl group), a phenylazophenyl group (more preferably a 4-phenylazophenyl group), or a hydrogen atom. Q ⁴² and Q ⁴³ are preferably the same as each other.

In general formula (P-II), Q ⁴² and Q ⁴³ are alkyl groups having 1 to 6 carbon atoms; or 6 or more carbon atoms optionally substituted by alkyl groups having 1 to 6 carbon atoms; It preferably represents an aryl group of 14 or less. In general formula (P-II), Q ⁴² and Q ⁴³ more preferably represent a methyl group, a phenyl group or a dimethylphenyl group (more preferably a 3,5-dimethylphenyl group). Q ⁴² and Q ⁴³ are preferably the same as each other. Q ⁴² and Q ⁴³ are preferably the same as each other.

A second specific example of the perylene pigment is a compound represented by general formula (P-III).

In general formula (P-III), Q ⁴⁴ to Q ⁴⁷ each independently represent a hydrogen atom or a monovalent organic group. ^Q44 and ^Q45 may combine with each other to form a ring. ^Q46 and ^Q47 may combine with each other to form a ring.

The monovalent organic groups represented by Q ⁴⁴ to Q ⁴⁷ in general formula (P-III) are synonymous with the monovalent organic groups represented by Q ⁴² and Q ⁴³ in general formula (P-II).

Examples of the ring formed by bonding Q ⁴⁴ and Q ⁴⁵ together and the ring formed by bonding Q ⁴⁶ and Q ⁴⁷ together include, for example, an aromatic hydrocarbon ring, an aromatic heterocyclic ring, and an alicyclic ring. hydrocarbon rings, and alicyclic heterocycles. The ring formed by bonding Q ⁴⁴ and Q ⁴⁵ together and the ring formed by bonding Q ⁴⁶ and Q ⁴⁷ together are preferably a benzene ring, a naphthalene ring, a pyridine ring, or a tetrahydronaphthalene ring. , a benzene ring or a naphthalene ring are more preferred. The benzene ring and naphthalene ring formed by bonding Q ⁴⁴ and Q ⁴⁵ to each other are each condensed with the imidazole ring to which Q ⁴⁴ and Q ⁴⁵ are bonded. The benzene ring and naphthalene ring formed by bonding Q ⁴⁶ and Q ⁴⁷ to each other are each condensed with the imidazole ring to which Q ⁴⁶ and Q ⁴⁷ are bonded.

The ring formed by combining Q ⁴⁴ and Q ⁴⁵ and the ring formed by combining Q ⁴⁶ and Q ⁴⁷ may each be substituted with a substituent. Such a substituent is preferably a halogen atom, more preferably a chlorine atom or a fluorine atom.

In general formula (P-III), Q ⁴⁴ and Q ⁴⁵ are bonded to each other to form an aromatic hydrocarbon ring having 6 or more and 10 or less carbon atoms which may be substituted with a halogen atom. is preferred. Q ⁴⁶ and Q ⁴⁷ are preferably bonded to each other to form an aromatic hydrocarbon ring having 6 or more and 10 or less carbon atoms which may be substituted with a halogen atom.

In general formula (P-III), Q ⁴⁴ and Q ⁴⁵ preferably combine with each other to form a benzene ring, chlorobenzene ring, fluorobenzene ring, or naphthalene ring. Q ⁴⁶ and Q ⁴⁷ preferably combine with each other to form a benzene ring, chlorobenzene ring, fluorobenzene ring, or naphthalene ring.

More preferred examples of perylene pigments include perylene pigments represented by the following chemical formulas (P1) to (P17) (hereinafter, each may be referred to as perylene pigments (P1) to (P17)). . The substitution positions of the pyridyl group in chemical formula (P5) and the fluoro group in chemical formula (P12) are not particularly limited.

Perylene pigments (P1) to (P3), (P5), (P6), (P9), (P10), (P11), and (P14) to (P17) are represented by general formula (P-II). is a suitable example of a perylene pigment. Perylene pigments (P4), (P7), (P8), and (P12) are suitable examples of perylene pigments represented by general formula (P-III). The perylene pigment (P13) is a suitable example of a perylene pigment other than the perylene pigments represented by general formulas (P-II) and (P-III).

Perylene pigment (P1), (P2), or (P3) is preferable as the perylene pigment in order to improve abrasion resistance and charge stability of the photoreceptor.

The n-type pigment may be an n-type pigment other than the perylene pigment and the azo pigment (hereinafter, may be referred to as other n-type pigment). Other n-type pigments include, for example, polycyclic quinone-based pigments, squarylium-based pigments, pyranthrone-based pigments, perinone-based pigments, isoindoline-based pigments, quinacdrine-based pigments, pyrazolone-based pigments, and benzimidazolone-based pigments. .

The photosensitive layer may contain only one n-type pigment, or may contain two or more n-type pigments. In order to improve the wear resistance and charging stability of the photoreceptor, the content of the n-type pigment is preferably greater than 0.00 parts by weight and 0.00 parts by weight with respect to 1.00 parts by weight of the charge generating agent. 01 parts by mass or more, more preferably 0.50 parts by mass or more. In order to improve abrasion resistance and charging stability of the photoreceptor, the content of the n-type pigment is preferably 3.00 parts by mass or less with respect to 1.00 parts by mass of the charge generating agent. It is more preferably 0.70 parts by mass or less, still more preferably 2.00 parts by mass or less, and particularly preferably 1.00 parts by mass or less. When the photosensitive layer contains two or more n-type pigments, this content means the total content of two or more n-type pigments.

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

(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.

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 pigment is preferable, a metal-free phthalocyanine or titanyl phthalocyanine is more preferable, and an X-type metal-free phthalocyanine or a Y-type titanyl phthalocyanine is even more preferable, because it has a high quantum yield in a wavelength region of 700 nm or more. , Y-type titanyl phthalocyanines are particularly preferred. Such charge-generating agents not only have a high quantum yield in the wavelength region of 700 nm or more, but also disperse well in the photosensitive layer by interacting with the n-type pigment.

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.

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 5 parts by mass or less with respect to 100 parts by mass of the binder resin.

(Electron transport agent)
Examples of electron transport agents include quinone compounds, diimide compounds, hydrazone compounds, malononitrile compounds, thiopyran compounds, trinitrothioxanthone compounds, 3,4,5,7-tetranitro-9-fluorenone compounds, dinitroanthracene compounds, dinitroacridine compounds, tetracyanoethylene, 2,4,8-trinitrothioxanthone, dinitrobenzene, 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. The photosensitive layer may contain only one electron transport agent, or may contain two or more electron transport agents.

Suitable examples of the electron transport agent for improving abrasion resistance and charging stability of the photoreceptor include the following general formulas (10), (11), (12), (13), and (14). (hereinafter each may be referred to as electron transport agents (10), (11), (12), (13) and (14)).

In general formula (10), Q ¹ , Q ² , Q ³ and Q ⁴ are each independently a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, It represents an aryl group having 6 to 14 carbon atoms or an aralkyl group having 7 to 20 carbon atoms.

In general formula (10), Q ¹ , Q ² , Q ³ and Q ⁴ preferably each independently represent a hydrogen atom or an alkyl group having 1 to 6 carbon atoms. Q ¹ and Q ⁴ each independently represent an alkyl group having 1 to 6 carbon atoms, and Q ² and Q ³ more preferably represent a hydrogen atom. The alkyl group having 1 to 6 carbon atoms represented by Q ¹ , Q ² , Q ³ and Q ⁴ is preferably an alkyl group having 1 to 5 carbon atoms, more preferably a 1,1-dimethylpropyl group. .

In general formula (11), Q ⁵ represents an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 14 carbon atoms. Q6 is an alkyl group having 1 to ⁶ carbon atoms, an aryl group having 6 to 14 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, an aralkyl group having 7 to 20 carbon atoms, a carbon atom represents an aryloxy group having 6 or more and 14 or less, or an aralkyloxy group having 7 or more and 20 or less carbon atoms. Q7 represents an alkyl group having 1 to ⁶ carbon atoms. v represents an integer of 0 or more and 4 or less.

In general formula (11), Q ⁵ preferably represents an aryl group having 6 to 14 carbon atoms, more preferably a phenyl group. Q ⁶ preferably represents an aralkyloxy group having 7 to 20 carbon atoms, more preferably an aralkyloxy group having 7 to 10 carbon atoms, and still more preferably a benzyloxy group. v preferably represents 0.

In general formula (12), Q ⁸ and Q ⁹ are each independently an aryl group having 6 or more and 14 or less carbon atoms, which may be substituted with at least one alkyl group having 1 or more and 6 or less carbon atoms. represents

In general formula (12), Q ⁸ and Q ⁹ each independently have 6 or more carbon atoms substituted with 2 or more and 5 or less (e.g., 2) alkyl groups having 1 or more and 6 or less carbon atoms. It preferably represents an aryl group of 14 or less, more preferably represents a phenyl group substituted with 2 or more and 5 or less (for example, 2) alkyl groups having 1 or more and 3 or less carbon atoms, ethylmethylphenyl more preferably represents a group, particularly preferably a 2-ethyl-6-methylphenyl group.

In general formula (13), Q ¹⁰ , Q ¹¹ , Q ¹² and Q ¹³ are each independently a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, represents an alkoxy group having 1 to 6 carbon atoms, an aryl group having 6 to 14 carbon atoms, an aralkyl group having 7 to 20 carbon atoms, or a heterocyclic group having 3 to 14 carbon atoms.

In general formula (13), Q ¹⁰ , Q ¹¹ , Q ¹² and Q ¹³ preferably each independently represent an alkyl group having 1 to 6 carbon atoms, and an alkyl group having 1 to 4 carbon atoms. group, and more preferably a methyl group or a tert-butyl group.

In general formula (14), Q ¹⁴ , Q ¹⁵ , and Q ¹⁶ are each independently an alkyl group having 1 to 6 carbon atoms, or 6 to 14 carbon atoms optionally substituted with a halogen atom. represents an aryl group of

In general formula (14), Q ¹⁴ and Q ¹⁵ each independently preferably represent an alkyl group having 1 to 6 carbon atoms, more preferably an alkyl group having 1 to 4 carbon atoms. Preferably, it more preferably represents a tert-butyl group. Q ¹⁶ preferably represents a halogen-substituted aryl group having 6 to 14 carbon atoms, more preferably a halogen-substituted phenyl group, still more preferably a chlorophenyl group. - is particularly preferred to represent a chlorophenyl group.

In order to improve the abrasion resistance and charging stability of the photoreceptor, more preferred examples of the electron transport agent are represented by chemical formulas (ET1), (ET2), (ET3), (ET4), and (ET5). represented compounds (hereinafter each may be described as an electron transport agent (ET1), (ET2), (ET3), (ET4), and (ET5)).

The electron transport agent (ET1) is a preferred example of the electron transport agent (10). Electron transport agent (ET2) is a suitable example of electron transport agent (11). Electron transport agent (ET3) is a suitable example of electron transport agent (12). Electron transport agent (ET4) is a suitable example of electron transport agent (13). Electron transport agent (ET5) is a suitable example of electron transport agent (14).

The content of the electron transport agent is preferably 5 parts by mass or more and 150 parts by mass or less, and preferably 10 parts by mass or more and 50 parts by mass or less with respect to 100 parts by mass of the binder resin.

(Hole transport agent)
Examples of hole transport agents include oxadiazole compounds (eg, 2,5-di(4-methylaminophenyl)-1,3,4-oxadiazole), styryl compounds (eg, 9-(4 -diethylaminostyryl)anthracene), carbazole compounds (e.g., polyvinylcarbazole), organic polysilane compounds, pyrazoline compounds (e.g., 1-phenyl-3-(p-dimethylaminophenyl)pyrazoline), hydrazone compounds, indole compounds, oxazole compounds, isoxazole-based compounds, thiazole-based compounds, 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 for improving abrasion resistance and charging stability of the photoreceptor include those represented by the following general formulas (20), (21), (22), (23) and (24). , (25), (26), and (27) (hereinafter referred to as hole transport agents (20), (21), (22), (23), (24), (25 ), (26), and (27)).

In general formula (20), R ¹¹ , R ¹² , R ¹³ , R ¹⁴ , R ¹⁵ and R ¹⁶ each independently represent an alkyl group having 1 to 8 carbon atoms or a phenyl group. R ¹⁷ and R ¹⁸ 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 (20), when b1 represents an integer of 2 or more and 5 or less, a plurality of R ¹¹ may be the same or different. When b2 represents an integer of 2 or more and 5 or less, a plurality of R ¹² may be the same or different. When b3 represents an integer of 2 or more and 5 or less, a plurality of R ¹³ may be the same or different. When b4 represents an integer of 2 or more and 5 or less, a plurality of R ¹⁴ may be the same or different. When b5 represents an integer of 2 or more and 4 or less, a plurality of R ¹⁵ may be the same or different. When b6 represents an integer of 2 or more and 4 or less, a plurality of R ¹⁶ may be the same or different.

In general formula (20), R ¹¹ , R ¹² , R ¹³ , R ¹⁴ , R ¹⁵ and R ¹⁶ preferably each independently represent an alkyl group having 1 to 8 carbon atoms, and It is more preferable to represent 1 or more and 3 or less alkyl groups, and it is further preferable to represent a methyl group or an ethyl group. R ¹⁷ and R ¹⁸ preferably represent a hydrogen atom. 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; As already mentioned, d and e each independently represent 0 or 1.

In general formula (21), R ²⁰ is substituted with a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, an alkoxy group having 1 to 8 carbon atoms, or an alkyl group having 1 to 8 carbon atoms. represents a phenyl group that may be R ²¹ , R ²² and R ²³ each independently represent an alkyl group having 1 to 8 carbon atoms or an alkoxy group having 1 to 8 carbon atoms. f1, f2, and f3 each independently represent an integer of 0 or more and 5 or less. f4 represents 0 or 1;

In general formula (21), when f1 represents an integer of 2 or more and 5 or less, a plurality of R ²¹ may be the same or different. When f2 represents an integer of 2 or more and 5 or less, a plurality of R ²² may be the same or different. When f3 represents an integer of 2 or more and 5 or less, a plurality of R ²³ may be the same or different.

In general formula (21), R ²⁰ preferably represents a phenyl group optionally substituted with an alkyl group having 1 to 8 carbon atoms, more preferably a phenyl group. R ²¹ , R ²² , and R ²³ each independently preferably represent an alkyl group having 1 to 8 carbon atoms, more preferably an alkyl group having 1 to 3 carbon atoms, and a methyl group; It is even more preferred to represent f1, f2, and f3 preferably each independently represent 0 or 1. As already mentioned, f4 represents 0 or 1.

In general formula (22), R ³¹ , R ³² , R ³³ , R ³⁴ and R ³⁵ each independently represent an alkyl group having 1 to 8 carbon atoms or an alkoxy group having 1 to 8 carbon atoms. show. g1, g2, g3, g4 and g5 each independently represents an integer of 0 or more and 5 or less.

In general formula (22), when g1 represents an integer of 2 or more and 5 or less, a plurality of R ³¹ may be the same or different. When g2 represents an integer of 2 or more and 5 or less, a plurality of R ³² may be the same or different. When g3 represents an integer of 2 or more and 5 or less, a plurality of R ³³ may be the same or different. When g4 represents an integer of 2 or more and 5 or less, a plurality of R ³⁴ may be the same or different. When g5 represents an integer of 2 or more and 5 or less, a plurality of R ³⁵ may be the same or different.

In general formula (22), R ³¹ , R ³² , R ³³ , R ³⁴ and R ³⁵ preferably each independently represent an alkyl group having 1 to 8 carbon atoms, It is more preferable to represent the following alkyl groups, and it is even more preferable to represent a methyl group. g1, g2, g3, g4 and g5 preferably represent one.

In general formula (23), R ⁴¹ , R ⁴² , R ⁴³ , R ⁴⁴ , R ⁴⁵ and R ⁴⁶ each independently represent an alkyl group having 1 to 8 carbon atoms, a phenyl group, or 1 carbon atom. Represents an alkoxy group of more than or equal to 8 or less. h1, h2, h4 and h5 each independently represents an integer of 0 or more and 5 or less. h3 and h6 each independently represent an integer of 0 or more and 4 or less.

In general formula (23), when h1 represents an integer of 2 or more and 5 or less, a plurality of R ⁴¹ may be the same or different. When h2 represents an integer of 2 or more and 5 or less, a plurality of R ⁴² may be the same or different. When h4 represents an integer of 2 or more and 5 or less, a plurality of R ⁴⁴ may be the same or different. When h5 represents an integer of 2 or more and 5 or less, a plurality of R ⁴⁵ may be the same or different. When h3 represents an integer of 2 or more and 4 or less, a plurality of R ⁴³ may be the same or different. When h6 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 (23), R ⁴¹ , R ⁴² , R ⁴³ , R ⁴⁴ , R ⁴⁵ and R ⁴⁶ preferably each independently represent an alkyl group having 1 to 8 carbon atoms, and It is more preferable to represent 1 or more and 3 or less alkyl groups, and it is further preferable to represent a methyl group or an ethyl group. It is preferable that h1, h2, h4 and h5 each independently represent an integer of 0 or more and 2 or less. h3 and h6 preferably represent 0;

In general formula (24), R ⁶¹ , R ⁶² and R ⁶³ each independently represent an alkyl group having 1 to 8 carbon atoms. R ⁶⁴ , R ⁶⁵ and R ⁶⁶ each independently represent a hydrogen atom or an alkyl group having 1 to 8 carbon atoms.

In general formula (24), R ⁶¹ , R ⁶² and R ⁶³ each independently preferably represent an alkyl group having 1 to 8 carbon atoms, and represent an alkyl group having 1 to 3 carbon atoms. is more preferred, and it is even more preferred to represent a methyl group. R ⁶⁴ , R ⁶⁵ and R ⁶⁶ preferably represent a hydrogen atom.

In general formula (25), R ⁷¹ , R ⁷² , R ⁷³ and R ⁷⁴ each independently represent an alkyl group having 1 to 8 carbon atoms. j1, j2, j3 and j4 each independently represents an integer of 0 or more and 5 or less. j5 represents 0 or 1;

In general formula (25), when j1 represents an integer of 2 or more and 5 or less, a plurality of R ⁷¹ may be the same or different. When j2 represents an integer of 2 or more and 5 or less, a plurality of R ⁷² may be the same or different. When j3 represents an integer of 2 or more and 5 or less, a plurality of R ⁷³ may be the same or different. When j4 represents an integer of 2 or more and 5 or less, a plurality of R ⁷⁴ may be the same or different.

In general formula (25), R ⁷¹ , R ⁷² , R ⁷³ and R ⁷⁴ each independently preferably represent an alkyl group having 1 to 3 carbon atoms, and may represent a methyl group or an ethyl group. more preferred. Preferably, j1, j2, j3 and j4 each independently represent 0 or 1. As already mentioned, j5 represents 0 or 1.

In general formula (26), R ⁸¹ , R ⁸² and R ⁸³ 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 ⁸⁴ and R ⁸⁵ 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; k1, k2, and k3 each independently represent an integer of 0 to 5; k4 and k5 each independently represent 1 or 2;

In general formula (26), when k1 represents an integer of 2 or more and 5 or less, a plurality of R ⁸¹ may be the same or different. When k2 represents an integer of 2 or more and 5 or less, a plurality of R ⁸² may be the same or different. When k3 represents an integer of 2 or more and 5 or less, a plurality of R ⁸³ may be the same or different.

In general formula (26), R ⁸¹ , R ⁸² and R ⁸³ each independently preferably represent an alkyl group having 1 to 8 carbon atoms, and represent an alkyl group having 1 to 6 carbon atoms. is more preferred, and it is even more preferred to represent a methyl group, an ethyl group, or an n-butyl group. R ⁸⁴ and R ⁸⁵ preferably represent a hydrogen atom. Each of k1, k2, and k3 preferably independently represents an integer of 0 or more and 2 or less. As already mentioned, k4 and k5 each independently represent 1 or 2.

In general formula (27), R ⁹¹ , R ⁹² and R ⁹³ each independently represent an alkyl group having 1 to 8 carbon atoms. R ⁹⁴ represents an alkyl group having 1 to 8 carbon atoms or a hydrogen atom. v1, v2, and v3 each independently represent an integer of 0 or more and 5 or less.

In general formula (27), when v1 represents an integer of 2 or more and 5 or less, a plurality of R ⁹¹ may be the same or different. When v2 represents an integer of 2 or more and 5 or less, a plurality of R ⁹² may be the same or different. When v3 represents an integer of 2 or more and 5 or less, a plurality of R ⁹³ may be the same or different.

In general formula (27), R ⁹⁴ preferably represents a hydrogen atom. v1, v2 and v3 preferably represent zero.

Preferred examples of the hole transport agent for improving abrasion resistance and charging stability of the photoreceptor include chemical formulas (HT1), (HT2), (HT3), (HT4), (HT5), Compounds represented by (HT6), (HT7), (HT8), (HT9), (HT10), (HT11), (HT12), (HT13), and (HT14) (hereinafter each referred to as hole transport Agents (HT1), (HT2), (HT3), (HT4), (HT5), (HT6), (HT7), (HT8), (HT9), (HT10), (HT11), (HT12), ( HT13) and (sometimes referred to as (HT14)).

The hole transport agents (HT1) and (HT2) are each suitable examples of the hole transport agent (20). Hole transport agents (HT3) and (HT4) are each suitable examples of hole transport agents (21). A hole transport agent (HT5) is a suitable example of a hole transport agent (22). Hole transport agents (HT6) and (HT7) are each suitable examples of hole transport agents (23). A hole transport agent (HT8) is a suitable example of a hole transport agent (24). Hole transport agents (HT9), (HT10), and (HT11) are each suitable examples of hole transport agents (25). Hole transport agents (HT12) and (HT13) are each suitable examples of hole transport agent (26). Hole transport agent (HT14) is a suitable example of hole transport agent (27).

The content of the hole transport agent is preferably 10 parts by mass or more, more preferably 50 parts by mass or more, and even more preferably 65 parts by mass or more, relative to 100 parts by mass of the binder resin. The content of the hole transport agent is preferably 300 parts by mass or less, more preferably 100 parts by mass or less, and even more preferably 75 parts by mass or less, relative to 100 parts by mass of the binder resin.

(combination of materials)
In order to improve the abrasion resistance and charging stability of the photoreceptor, the combination of the n-type pigment and the binder resin is the combination No. 1 shown in Table 1. Each of D1 to D33 is preferred. For the same reason, the combination of the n-type pigment and the binder resin is the combination No. 1 shown in Table 1. Each of D1 to D33, and the charge generating agent is preferably Y-type titanyl phthalocyanine.

In order to improve the wear resistance and charging stability of the photoreceptor, the combination of the hole transport agent, the n-type pigment, and the binder resin, as shown in Table 2, is recommended. Each of E1 to E59 is preferred. For the same reason, the combination of the hole transport agent, the n-type pigment, and the binder resin is the combination No. shown in Table 2. Each of E1 to E59, and the charge generating agent is preferably Y-type titanyl phthalocyanine.

In order to improve the wear resistance and charging stability of the photoreceptor, combination Nos. shown in Tables 3 and 4 of the hole transport agent, the electron transport agent, the n-type pigment, and the binder resin are recommended. Each of F1 to F67 is preferred. For the same reason, the combination of the hole transport agent, the electron transport agent, the n-type pigment, and the binder resin is the combination No. shown in Table 3. It is each of F1 to F67, and the charge generating agent is preferably Y-type titanyl phthalocyanine.

In Tables 1 to 4, "No." indicates "Combination No.," "n-type" indicates "n-type pigment," "HTM" indicates "hole transport agent," and "ETM." ” indicates an “electron transport agent”, and “resin” indicates a polyarylate resin that is a binder resin.

(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 those of the binder resin already described. 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)
Next, an example of a method for manufacturing a photoreceptor will be described. A photoreceptor manufacturing method 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 photosensitive layer coating liquid) is prepared. A coating solution for a photosensitive layer is applied onto a conductive substrate. Next, at least part of the solvent contained in the coated photosensitive layer coating liquid 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, an n-type pigment, and a solvent. The photosensitive layer coating liquid is prepared by dissolving or dispersing a charge generating agent, a hole transporting agent, an electron transporting agent, a binder resin, and an n-type pigment 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 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 coating liquid for the photosensitive layer 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 for applying the photosensitive layer coating liquid is not particularly limited as long as it is a method capable of uniformly applying the photosensitive layer 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 photosensitive layer coating solution include, for example, heating, reduced pressure, or combined use of heating and reduced pressure. More specifically, a method of heat treatment (hot air drying) using a high-temperature dryer or a reduced-pressure dryer can be mentioned. 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.

<Image forming apparatus>
Next, an image forming apparatus including the photoreceptor 1 of this embodiment will be described. A tandem color image forming apparatus will be described below 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 110 shown in FIG. 4 includes image forming units 40 a , 40 b , 40 c and 40 d , a transfer belt 50 and a fixing device 52 . Hereinafter, each of the image forming units 40a, 40b, 40c, and 40d will be referred to as the image forming unit 40 when there is no need to distinguish between them.

The image forming unit 40 includes an image carrier 100 , a charging device 42 , an exposure device 44 , a developing device 46 , a transfer device 48 and a cleaning device 54 . The image carrier 100 is the photoreceptor 1 of this embodiment.

As already described, the photoreceptor 1 of this embodiment is excellent in abrasion resistance and charging stability. Therefore, by including the photoreceptor 1 as the image carrier 100, the image forming apparatus 110 is excellent in durability and can form a good image on the recording medium P. FIG.

An image carrier 100 is provided at a central position of the image forming unit 40 . The image carrier 100 is rotatable in the arrow direction (counterclockwise). Around the image carrier 100, there are a charging device 42, an exposure device 44, a developing device 46, a transfer device 48, and a cleaning device 54 in the order described from the upstream side in the rotational direction of the image carrier 100. be provided.

Each of the image forming units 40a to 40d sequentially superimposes toner images of a plurality of colors (for example, four colors of black, cyan, magenta, and yellow) on the recording medium P on the transfer belt 50. FIG.

The charging device 42 positively charges the surface (for example, the peripheral surface) of the image carrier 100 . The charging device 42 is, for example, a scorotron charger.

The exposure device 44 irradiates the charged surface of the image carrier 100 with light. That is, the exposure device 44 exposes the charged surface of the image carrier 100 . Thereby, an electrostatic latent image is formed on the surface of the image carrier 100 . The electrostatic latent image is formed based on image data input to image forming apparatus 110 .

The developing device 46 supplies toner to the surface of the image carrier 100 and develops the electrostatic latent image into a toner image. The developing device 46 is in contact with the surface of the image carrier 100 . That is, the image forming apparatus 110 employs the 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 a one-component developer, to the electrostatic latent image formed on the image carrier 100 . When the developer is a two-component developer, the developing device 46 supplies the electrostatic latent image formed on the image carrier 100 with the toner, which is contained in the two-component developer, and the carrier. Thus, the image carrier 100 carries a toner image.

The time from when the predetermined area on the surface of the image carrier 100 passes through the exposure position PA until it reaches the development position PB (hereinafter sometimes referred to as exposure-development time) is 100 milliseconds or less. be. The exposure position PA is a position where the light emitted from the exposure device 44 is incident on the surface of the image carrier 100 . The development position PB is a position where the surface of the image carrier 100 contacts the development device 46 or is closest to the development device 46 . The predetermined area is, for example, one point on the surface of the image carrier 100 .

The transfer belt 50 conveys the recording medium P between the image carrier 100 and the transfer device 48 . The transfer belt 50 is an endless belt. The transfer belt 50 is rotatable in the arrow direction (clockwise).

The transfer device 48 transfers the toner image developed by the developing device 46 from the surface of the image carrier 100 to the recording medium P which is a transfer target. Specifically, when the transfer device 48 transfers the toner image from the surface of the image carrier 100 to the recording medium P, the surface of the image carrier 100 and the recording medium P are in contact with each other. That is, the image forming apparatus 110 employs a direct transfer method. The transfer device 48 is, for example, a transfer roller.

The cleaning device 54 collects toner adhering to the surface of the image carrier 100 . The cleaning device 54 has a housing 541 and a cleaning roller 542 . Note that the cleaning device 54 does not have a cleaning blade. Cleaning roller 542 is disposed within housing 541 . Cleaning roller 542 is arranged to contact the surface of image carrier 100 . The cleaning roller 542 polishes the surface of the image carrier 100 and collects the toner adhering to the surface of the image carrier 100 into the housing 541 .

The recording medium P onto which the toner image has been transferred by the transfer device 48 is conveyed to the fixing device 52 by the transfer belt 50 . The fixing device 52 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 pressed by the fixing device 52 . The toner image is fixed on the recording medium P by heating and/or pressing the toner image. As a result, an image is formed on the recording medium P. FIG.

An example of the image forming apparatus has been described above, but the image forming apparatus is not limited to the image forming apparatus 110 described above. Although the image forming apparatus 110 is a color image forming apparatus, the image forming apparatus may be a monochrome image forming apparatus. In this case, the image forming apparatus may have, for example, only one image forming unit. Further, although the image forming apparatus 110 employs a tandem system, the image forming apparatus may employ, for example, a rotary system. Although the scorotron charger has been described as an example of the charging device 42, the charging device may be a charging device other than the scorotron charger (for example, a charging roller, a charging brush, or a corotron charger). Although the image forming apparatus 110 employs a contact developing method, the image forming apparatus may employ a non-contact developing method. Although the image forming apparatus 110 employs a direct transfer method, the image forming apparatus may 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 device 54 has the cleaning roller 542 and no cleaning blade, the cleaning device may have the cleaning roller 542 and the cleaning blade. Although the image forming unit 40 does not include a static eliminating device, the image forming unit may further comprise a static eliminating device.

<Process cartridge>
An example of a process cartridge including the photoreceptor 1 of this embodiment will be described with continued reference to FIG. A process cartridge corresponds to each of the image forming units 40a to 40d. A process cartridge includes an image carrier 100 . The image carrier 100 is the photoreceptor 1 of this embodiment. As already described, the photoreceptor 1 of this embodiment is excellent in abrasion resistance and charging stability. Therefore, by providing the photoreceptor 1 as the image carrier 100, the process cartridge has excellent durability and can form a good image on the recording medium P. FIG.

The process cartridge may further include at least one of the charging device 42 , the exposure device 44 , the developing device 46 , the transfer device 48 and the cleaning device 54 in addition to the image carrier 100 . That is, in addition to the image carrier 100, the process cartridge may further include at least one selected from the group consisting of the charging device 42, the exposure device 44, the developing device 46, the transfer device 48, and the cleaning device 54. good. The process cartridge may further include a static eliminator (not shown). The process cartridge is designed to be detachable from the image forming apparatus 110 . Therefore, the process cartridge is easy to handle, and when the sensitivity characteristics of the image carrier 100 deteriorate, the process cartridge including the image carrier 100 can be easily and quickly replaced. The process cartridge provided with the photoreceptor 1 of this embodiment has been described above with reference to FIG.

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.

<Material for Forming Photosensitive Layer>
First, as materials for forming the photosensitive layer of the photoreceptor, the following charge-generating agent, electron-transporting agent, hole-transporting agent, binder resin, and n-type pigment were prepared.

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

(Electron transport agent)
As electron transport agents, the electron transport agents (ET1) to (ET5) described in the embodiment were prepared.

(Hole transport agent)
As hole transport agents, the hole transport agents (HT1) to (HT14) described in the embodiment were prepared.

(binder resin)
As binder resins, the polyarylate resins (R1) to (R12) described in the embodiment were prepared. The viscosity average molecular weights of the polyarylate resins (R1) to (R12) were all 60,000.

Further, as binder resins used in Comparative Examples, polycarbonate resins having repeating units represented by chemical formulas (R13), (R14), and (R15) (hereinafter referred to as polycarbonate resins (R13), (R14), and (R15)) were prepared. The viscosity-average molecular weights of the polycarbonate resins (R13), (R14) and (R15) were all 60,000. Incidentally, the polycarbonate resin (R13) corresponds to the bisphenol Z-type polycarbonate resin described in prior art documents.

Further, as binder resins used in Comparative Examples, polyarylate resins having repeating units represented by the chemical formulas (R16) and (R17) (hereinafter referred to as polyarylate resins (R16) and (R17), respectively) prepared. The viscosity average molecular weights of the polyarylate resins (R16) and (R17) were both 50,000.

In the above chemical formulas (R13) to (R17), the number attached to the lower right of each repeating unit is the percentage (%) of each repeating unit with respect to the total number of repeating units contained in the polycarbonate resin or polyarylate resin. ).

(n-type pigment)
As n-type pigments, the azo pigments (A1) to (A4) and perylene pigments (P1) to (P3) described in the embodiment were prepared.

<Production of Photoreceptor>
Photoreceptors (A-1) to (A-37) using the charge generating agent, electron transport agent, hole transport agent, binder resin, and n-type pigment described in <Material for Forming Photosensitive Layer> ) and (B-1) to (B-6) were produced.

(Production of photoreceptor (A-1))
3.00 parts by mass of Y-type titanyl phthalocyanine as a charge generating agent, 70.00 parts by mass of a hole transport agent (HT1), 35.00 parts by mass of an electron transport agent (ET1), and a polyarylate resin (R1) as a binder resin 100.00 parts by mass, 2.00 parts by mass of an azo pigment (A1) that is an n-type pigment, and 800.00 parts by mass of tetrahydrofuran that is a solvent are mixed for 50 hours using a ball mill to obtain a coating liquid for a photosensitive layer. rice field. A coating liquid for a photosensitive layer was applied onto a conductive substrate (a drum-shaped support made of aluminum) by a dip coating method. The coated photosensitive layer coating solution was dried with hot air at 120° C. for 60 minutes. Thus, a photosensitive layer (thickness: 28 μm) was formed on the conductive substrate to obtain a photosensitive member (A-1). In the photoreceptor (A-1), a single layer of photoreceptor layer was provided directly on the conductive substrate.

(Production of photoreceptors (A-2) to (A-35) and (B-2) to (B-6))
Photoreceptor (A -2) to (A-35) and (B-2) to (B-6) were each produced.

(Production of photoreceptors (A-36) to (A-37))
Photoreceptor (A-36) to Photoreceptor (A-36) in the same manner as Photoreceptor (A-1) except that the amount of azo pigment (A1) added was changed from 2.00 parts by mass to the amount shown in Table 6. (A-37) were each produced.

(Production of photoreceptor (B-1))
A photoreceptor (B-1) was produced in the same manner as the photoreceptor (A-1), except that no n-type pigment was added.

<Evaluation>
The following evaluations were performed for each of the photoreceptors (A-1) to (A-37) and (B-1) to (B-6) to be evaluated.

[Evaluation of Abrasion Resistance of Photosensitive Layer]
The photosensitive layer coating liquid prepared in <Production of Photoreceptor> was applied to a polypropylene sheet wrapped around an aluminum pipe. The coated photosensitive layer coating solution was dried at 120° C. for 60 minutes to prepare a polypropylene sheet having a photosensitive layer (film thickness of 28 μm) formed thereon. Subsequently, the photosensitive layer was peeled off from the polypropylene sheet. The peeled photosensitive layer was attached to a card-like member ("S-36" manufactured by Taber Co.). The mass M _A of the card-like member with the photosensitive layer attached was measured. Next, the card-shaped member was attached to the turntable of a rotary abrasion tester (Toyo Seiki Seisakusho Co., Ltd.). Then, the turntable was rotated 500 times at a rotation speed of 60 rpm with an abrasion wheel ("CS-10" manufactured by Taber) having a load of 500 gf placed on the photosensitive layer on the card-shaped member. In this way, the photosensitive layer on the turntable was abraded. After the abrasion, the mass M _B of the card-like member with the photosensitive layer attached was measured again. Then, the abrasion loss (=M _A -M _B ), which is the change in mass of the photosensitive layer before and after abrasion, was obtained. The abrasion resistance of the photoreceptor was evaluated based on the following criteria from the abrasion loss. Tables 5 and 6 show the evaluation results of wear resistance. Photoreceptors rated C for abrasion resistance were evaluated as having poor abrasion resistance.

(Abrasion resistance evaluation criteria)
Evaluation A: Wear loss is less than 5 mg.
Evaluation B: Wear loss is 5 mg or more and less than 8 mg.
Evaluation C: Wear loss is 8 mg or more.

[Evaluation of charging stability of photoreceptor]
The evaluation environment for the charging stability of the photoreceptor was an environment with a temperature of 10° C. and a relative humidity of 15% RH. An evaluation machine (a modified machine of "FS-C5250DN" manufactured by Kyocera Document Solutions Co., Ltd.) was used to evaluate the charging stability. The evaluator was equipped with a scorotron charger and cleaning roller and no cleaning blade. The charging polarity of the scorotron charger was positive. The rotation speed of the photoreceptor was set so that the exposure-development time was 70 milliseconds.

First, using the evaluation machine, image A (full white paper image) was printed on three sheets of recording media (A4 size paper). When printing on each sheet, the surface potential of the photoreceptor was measured at the development position. Since exposure is not performed when printing a blank image, the measured surface potential corresponds to the charging potential. The surface potential was measured three times in total, once for printing one sheet of paper. The average value of the surface potentials measured three times was taken as the charging potential V ₀₁ (unit: +V) before the printing test.

A print test was then conducted. The printing test was a test in which image B (printing pattern image with a printing rate of 5%) was printed on 10,000 sheets of recording media (A4 size paper) at intervals of 15 seconds using an evaluator. Immediately after the printing test, image A (all white paper image) was printed on three recording media (A4 size paper). When printing on each sheet, the surface potential of the photoreceptor was measured at the development position. The surface potential was measured three times in total, once for printing one sheet of paper. The average value of the surface potentials measured three times was taken as the charging potential V ₀₂ (unit: +V) after the printing test.

A value obtained by subtracting the charge potential V ₀₂ after the print test from the charge potential V ₀₁ before the print test (V ₀₁ -V ₀₂ ) was defined as the charge potential drop ΔV ₀ (unit: V). The charge stability of the photoreceptor was evaluated from the charge potential drop amount ΔV ₀ based on the following criteria. Tables 5 and 6 show the evaluation results of charging stability. A photoreceptor having an evaluation of C for charging stability was evaluated as having poor charging stability.

(Evaluation criteria for charging stability)
Evaluation A: The charge potential drop amount ΔV ₀ is 0V or more and less than 60V.
Evaluation B: The charge potential drop amount ΔV ₀ is 60V or more and less than 110V.
Evaluation C: The charge potential drop amount ΔV ₀ is 110 V or more.

The meaning of each term in Tables 5 and 6 is as follows. "n-type" refers to n-type pigments. "HTM" indicates hole transport agent. "ETM" indicates an electron transport agent. "Resin" indicates a binder resin. The "amount" in the "n-type" column indicates the amount of the n-type pigment added to 3.00 parts by mass of the charge generating agent. "Parts" indicates parts by mass. "None" indicates that the corresponding component is not contained.

As shown in Tables 5 and 6, the photosensitive layers of photoreceptors (A-1) to (A-37) each contain one of polyarylate resins (R1) to (R12) as a binder resin. contained. Each of the polyarylate resins (R1) to (R12) is a polyarylate resin included in the polyarylate resin (PA) containing at least one type of repeating unit (1) and at least one type of repeating unit (2). there were. The photosensitive layers of the photoreceptors (A-1) to (A-37) each contain n-type pigments (more specifically, azo pigments (A1) to (A4) and perylene pigments (P1) to (P3). one of them) was contained. Photoreceptors (A-1) to (A-37) were evaluated as A or B in abrasion resistance, and the abrasion resistance of these photoreceptors was good. Further, the charging stability evaluation of the photoreceptors (A-1) to (A-37) was A or B, and the charging stability of these photoreceptors was good.

From the above, it was shown that the photoreceptor according to the present invention is excellent in abrasion resistance and charging stability. Since the photoreceptor according to the present invention is excellent in wear resistance and charging stability, the process cartridge and the image forming apparatus equipped with the photoreceptor according to the present invention are excellent in durability and can form good images.

A photoreceptor and a 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.

Claims (13)

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 transport agent, an electron transport agent, a binder resin, and an n-type pigment,
The binder resin contains a polyarylate resin, and the polyarylate resin includes at least one repeating unit represented by general formula (1) and at least one repeating unit represented by general formula (2). including
The electrophotographic photoreceptor , wherein the hole transport agent contains a compound represented by the chemical formula (HT2) or (HT3) .

(In the general formula (1), a represents 1 or 2,
In general formula (2), X represents a divalent group represented by chemical formula (X1), (X2), (X3), (X4), or (X5). )

2. The electrophotographic photoreceptor according to claim 1, wherein said n-type pigment is an azo pigment. 3. The electrophotographic photoreceptor according to claim 2, wherein the azo pigment is represented by chemical formula (A1), (A2), (A3), or (A4).

2. The electrophotographic photoreceptor according to claim 1, wherein said n-type pigment is a perylene pigment. 5. The electrophotographic photoreceptor according to claim 4, wherein the perylene pigment is represented by chemical formula (P1), (P2), or (P3).

2. The electrophotographic photoreceptor according to claim 1, wherein the content of said n-type pigment is 0.01 parts by mass or more and 3.00 parts by mass or less with respect to 1.00 parts by mass of said charge generating agent. The polyarylate resin is a polyarylate resin containing repeating units represented by the chemical formula (1-2) and the chemical formula (2-X3), or

2. The electrophotographic photoreceptor according to claim 1, which is a polyarylate resin containing repeating units represented by the chemical formulas (1-2) and (2-X5).

The polyarylate resin is a polyarylate resin containing repeating units represented by the chemical formulas (1-2), (2-X1), and (2-X4);

a polyarylate resin containing repeating units represented by the chemical formula (1-2), the chemical formula (2-X1), and the chemical formula (2-X3);

a polyarylate resin containing repeating units represented by the chemical formula (1-2), the chemical formula (2-X4), and the chemical formula (2-X3);

a polyarylate resin containing repeating units represented by the chemical formula (1-2), the chemical formula (2-X5), and the chemical formula (2-X3);

A polyarylate resin containing repeating units represented by the chemical formula (1-2), the chemical formula (2-X5), and the chemical formula (2-X1), or

2. The electrophotographic photoreceptor according to claim 1, which is a polyarylate resin containing repeating units represented by the chemical formula (1-1), the chemical formula (2-X1), and the chemical formula (2-X3).

The polyarylate resin is a polyarylate resin containing repeating units represented by chemical formula (1-1), chemical formula (1-2), chemical formula (2-X1), and chemical formula (2-X3). 1. The electrophotographic photoreceptor according to 1.

2. The electrophotographic photoreceptor according to claim 1, wherein the charge generating agent comprises metal-free phthalocyanine or metal phthalocyanine. 2. The electrophotographic photoreceptor according to claim 1, wherein the electron transport agent contains a compound represented by general formula (10), (11), (12), (13), or (14).

(In general formula (10), Q ¹ , Q ² , Q ³ , and Q ⁴ are each independently a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, group, an aryl group having 6 to 14 carbon atoms, or an aralkyl group having 7 to 20 carbon atoms,
In the general formula (11), Q ⁵ represents an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 14 carbon atoms, and Q ⁶ represents an alkyl group having 1 to 6 carbon atoms. an aryl group having 6 to 14 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, an aralkyl group having 7 to 20 carbon atoms, an aryloxy group having 6 to 14 carbon atoms, or a carbon atom represents an aralkyloxy group having a number of 7 or more and 20 or less, Q ⁷ represents an alkyl group having 1 or more and 6 or less carbon atoms, v represents an integer of 0 or more and 4 or less,
In the general formula (12), Q ⁸ and Q ⁹ are each independently an aryl group having 6 to 14 carbon atoms which may be substituted with at least one alkyl group having 1 to 6 carbon atoms. represents
In the general formula (13), Q ¹⁰ , Q ¹¹ , Q ¹² and Q ¹³ are each independently a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms , an alkoxy group having 1 to 6 carbon atoms, an aryl group having 6 to 14 carbon atoms, an aralkyl group having 7 to 20 carbon atoms, or a heterocyclic group having 3 to 14 carbon atoms,
In general formula (14), Q ¹⁴ , Q ¹⁵ , and Q ¹⁶ each independently represent an alkyl group having 1 to 6 carbon atoms, or 6 to 14 carbon atoms optionally substituted with a halogen atom. Represents the following aryl groups. ) A process cartridge comprising the electrophotographic photoreceptor according to claim 1 . a rotatable image carrier;
a charging device that positively charges the surface of the image carrier;
an exposure device that irradiates the charged surface of the image carrier with light 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 for transferring the toner image from the image carrier to a transfer target;
An image forming apparatus, wherein the image carrier is the electrophotographic photosensitive member according to claim 1 .

Images