JPH1025287A - Quinone derivative and electrophotographic photoreceptor using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a new specific quinone derivative that is suitable used as an electron transfer agent and useful as a highly sensitive electrophotographic photoreceptor for image forming equipment, such as electrostatic copiers, laser printers and facsimile machines. SOLUTION: This new quinone derivative that is suitably used as an electron transfer agent and useful as a highly sensitive electrophotographic photoreceptor for image forming equipment, such as electrostatic copiers, laser printers and facsimile machines comprises a new quinone derivative of formula I (R<1> and R<2> are each H, an alkyl or an alkoxy provided that R<1> and R<2> are not simultaneously H; R<3> is H, an alkyl, an aryl or an alkoxy), which is obtained by allowing a quinone of formula II (e.g. methyl-1,4-benzoquinone, etc.) to react with a β-naphthol of formula III in the presence of copper acetate or the like to form an intermediate of formula IV, and then reflecting the intermediate in a solvent such as pyridine together with a catalyst such as copper chloride.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel quinone derivative suitably used as an electron transporting agent, and an electrophotographic photosensitive member used in an image forming apparatus such as an electrostatic copying machine, a laser printer, and a facsimile.

[0002]

2. Description of the Related Art In recent years, various photoconductors having sensitivity in a wavelength region of a light source used in the image forming apparatus have been used. One is an inorganic photoreceptor using an inorganic material such as selenium for the photosensitive layer, and the other is an organic photoreceptor (OPC) using an organic material for the photosensitive layer. Organic photoreceptors are easier to manufacture than inorganic photoreceptors, and have a wide variety of photoreceptor materials, such as charge transport agents, charge generators, and binder resins, and a high degree of freedom in functional design. Extensive research is ongoing.

[0003] The organic photoreceptor contains a single-layer type photoreceptor in which a charge generating agent and a charge transporting agent are dispersed in the same photosensitive layer, and a charge generating layer containing a charge generating agent and a charge transporting agent. There is a laminated photoconductor in which a charge transport layer is laminated, and among these, a laminated photoconductor is generally used. In the laminated photoreceptor, from the viewpoint of mechanical strength, a charge transport layer having a thickness larger than that of the charge generation layer is generally disposed as the outermost layer.

A charge transporting agent used in an organic photoreceptor is required to have a high carrier mobility. Most of the charge transporting agents having a high carrier mobility have a hole transporting property. For this reason, the organic photoreceptors that are currently in practical use are negatively charged type laminated photoreceptors having a charge transport layer disposed on the outermost layer.
However, the negatively charged organic photoreceptor needs to be charged by a negative corona discharge, which generates a large amount of ozone, and the ozone affects the environment and deteriorates the photoreceptor itself.

In order to solve the above-mentioned problems, the use of an electron transporting agent as a charge transporting agent has been studied. For example, Japanese Patent Application Laid-Open No. Hei 1-206349 discloses the use of a diphenoquinone derivative as an electron transporting agent. An electrophotographic photoreceptor is disclosed.

[0006]

However, diphenoquinone derivatives generally have poor compatibility with binder resins,
Since the electrons are not uniformly dispersed in the photosensitive layer, the hopping distance of the electrons is long, and particularly, the electron transfer in a low electric field is unlikely to occur. Therefore, although the diphenoquinone derivative itself has a high carrier mobility, its properties are not sufficiently exhibited when it is used in a photoreceptor as an electron transport agent, the residual potential of the photoreceptor becomes high, and the sensitivity becomes insufficient. Problem.

A single-layer photoreceptor has the advantage that one photoreceptor can be used for both positively and negatively charged types by using an electron transporting agent and a hole transporting agent in combination. When the diphenoquinone derivative is used as an electron transporting agent, a problem arises in that a charge transfer complex is formed by interaction with the hole transporting agent, and the transport of electrons and holes is inhibited.

Therefore, an object of the present invention is to solve the above technical problems and to provide a novel compound suitable as an electron transporting agent in an electrophotographic photoreceptor. Another object of the present invention is to provide a highly sensitive electrophotographic photosensitive member.

[0009]

Means for Solving the Problems The inventors of the present invention have made intensive studies to solve the above-mentioned problems, and as a result, the general formula (1):

[0010]

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(Wherein, R ¹ and R ² are the same or different and each represent a hydrogen atom, an alkyl group or an alkoxy group, and R ³ represents a hydrogen atom, an alkyl group, an aryl group or an alkoxy group, provided that R ¹ And R ² are not hydrogen atoms at the same time.)
The present inventors have found a new fact that they have a higher electron transporting ability than conventional diphenoquinone derivatives, and have completed the present invention.

The quinone derivative represented by the general formula (1) has good solubility in a solvent and compatibility with a binder resin, and has excellent matching with a charge generating agent. In addition, it has a strong effect of extracting charges (electrons) generated by the charge generating agent, and is excellent in electron acceptability. Furthermore, since the quinone derivative (1) has a large π-electron spread in the molecule and a high planarity of the molecule, the quinone derivative (1) has higher stability than the conventional diphenoquinone derivative and has a hole that inhibits charge transport. No interaction with the transport agent occurs. Therefore, the above quinone derivative
By using (1) as an electron transporting agent, a highly sensitive photoreceptor can be provided.

The electrophotographic photoreceptor of the present invention is an electrophotographic photoreceptor having a photosensitive layer provided on a conductive substrate, wherein the photosensitive layer contains a quinone derivative represented by the general formula (1). Features. According to the above configuration, the residual potential decreases,
An electrophotographic photosensitive member having high sensitivity can be obtained.

The photosensitive layer may have an oxidation-reduction potential of -0.8 together with the quinone derivative represented by the general formula (1).
By containing an electron accepting compound having a voltage of from -1.4 V, a photoreceptor with further improved sensitivity can be obtained.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First, the quinone derivative (1) of the present invention
Will be described in detail. In the general formula (1), as the groups corresponding to the substituents R ¹ and R ² , in addition to a hydrogen atom, for example, methyl, ethyl, n-propyl, isopropyl, n-
An alkyl group having 1 to 6 carbon atoms such as butyl, isobutyl, s-butyl, t-butyl, n-pentyl, n-hexyl, methoxy, ethoxy, n-propoxy, isopropoxy, t-butoxy, n-pentyloxy And alkoxy groups having 1 to 6 carbon atoms such as n-hexyloxy and the like. Note that the groups R ¹ and R ² are not simultaneously hydrogen atoms.

In the general formula (1), examples of the group corresponding to the substituent R ³ include a hydrogen atom, the above-mentioned alkyl group and alkoxy group, and phenyl, naphthyl, anthryl, phenanthryl, fluorenyl, biphenylyl, o
And aryl groups such as terphenyl. General formula
Specific examples of the quinone derivative represented by (1) include, for example, compounds represented by the following formulas (1-1) to (1-4).

[0017]

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The quinone derivative (1) of the present invention is synthesized, for example, as shown in the following reaction formula (I). That is, first, a benzoquinone derivative (2) and a β-naphthol derivative (3) are mixed in a solvent such as acetic acid with copper acetate or iron chloride (II).
By heating to 50 to 110 ° C. together with a catalyst such as I), an intermediate represented by the general formula (4) is obtained. Then this intermediate
The quinone derivative (1) is obtained by refluxing (4) in a solvent such as pyridine with a catalyst such as copper chloride.

Reaction formula (I):

[0020]

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Next, the electrophotographic photosensitive member of the present invention will be described in detail. The electrophotographic photoreceptor of the present invention has the general formula
A photosensitive layer containing the quinone derivative represented by (1) as an electron transporting agent is provided on a conductive substrate. The photosensitive layer includes a so-called single layer type and a laminated type. The photoreceptor of the present invention can be applied to both the single-layer type and the laminated type.

The single-layer type photoreceptor is provided with a single photosensitive layer containing a quinone derivative (1) as an electron transporting agent and a charge generating agent on a conductive substrate. Such a single-layer type photosensitive layer can cope with either positive or negative charging by a single structure, but is preferably used in a positive charging type which does not require the use of a negative corona discharge. The single-layer type photoreceptor has the advantages that the layer configuration is simple and excellent in productivity, that the occurrence of film defects in the photosensitive layer can be suppressed, and that the optical characteristics can be improved because the number of interfaces between the layers is small. .

The above quinone derivative which is an electron transporting agent
The single-layer type photoreceptor using (1) in combination with a hole transporting agent having excellent hole transporting properties does not cause the interaction between the quinone derivative (1) and the hole transporting agent as described above. Even when both transporting agents are contained in the same photosensitive layer at a high concentration, electron transport and hole transport can be efficiently performed, respectively, and a highly sensitive photoreceptor can be obtained.

On the other hand, the laminated type photoreceptor is formed on a conductive substrate.
A charge generating layer containing a charge generating agent and a charge transporting layer containing a charge transporting agent are laminated in this order or in the reverse order. However, since the charge generation layer is very thin compared to the charge transport layer, it is preferable to form the charge generation layer on a conductive substrate and to form the charge transport layer thereon for protection. .

Depending on the order of forming the charge generation layer and the charge transport layer and the type of the charge transport agent used in the charge transport layer, the photoreceptor is selected to be either positive or negative. . For example, in a layer configuration in which a charge generation layer is formed on a conductive substrate and a charge transport layer is formed thereon, an electron transport agent such as the quinone derivative (1) is used as the charge transport agent in the charge transport layer. In this case, the photosensitive member becomes a positive charging type photosensitive member. In this case, the charge generation layer may contain a hole transporting agent. On the other hand, in the above layer configuration, when a hole transporting agent is used as the charge transporting agent in the charge transporting layer, a negatively charged photoreceptor is obtained. In this case, the charge generation layer may contain an electron transport agent.

In the photoreceptor of the present invention, an electron-accepting compound having an oxidation-reduction potential of -0.8 to -1.4 V together with the quinone derivative (electron transporting agent) represented by the general formula (1). By including the compound in the photosensitive layer, the effect that the residual potential is greatly reduced and the sensitivity of the photosensitive member is further improved can be obtained. The above-mentioned electron accepting compound has an LU
The MO (Lowest Unoccupied Molecular Orbital, lowest unoccupied molecular orbital) has a lower energy compliance than that of the charge generating agent, so when light-irradiation generates an ion pair of electrons (-) and holes (+) in the charge generating agent. Electrons are efficiently extracted from the charge generating agent. For this reason, the rate of disappearance of ion pairs due to recombination of electrons and holes is reduced, and charge generation efficiency is improved. Further, the electron-accepting compound is a quinone derivative which is an electron-transporting agent for extracting electrons extracted from the charge-generating agent.
(1) It also works to communicate efficiently. For this reason, in the combined use system of the quinone derivative (1) and the electron-accepting compound, the injection and transport of electrons from the charge generating agent are performed smoothly, and the sensitivity of the photoreceptor is further improved.

The oxidation-reduction potential of the electron-accepting compound is limited within the above range for the following reason. That is,
An electron-accepting compound having an oxidation-reduction potential higher than -0.8 V lowers the traveling electrons to a level at which detrapping is impossible while repeating trap-detrap, thereby causing carrier trapping. Since this carrier trap hinders electron transport, the sensitivity of the photoreceptor decreases. Conversely, an electron-accepting compound having a redox potential lower than -1.4 V has a higher LUMO energy level than the charge generating agent, and does not transfer electrons to the electron-accepting compound when the ion pair is generated. It does not lead to improvement in charge generation efficiency. The oxidation-reduction potential of the electron-accepting compound is preferably from -0.85 to -1.00 V even in the above range.

The redox potential, E ₁ shown in FIG from the relationship as shown in FIG. 1, the traction voltage (V) and current (.mu.A)
The and E ₂ was determined and calculated using the following equation. Oxidation-reduction potential (V) = (E ₁ + E ₂ ) / 2 The above pulling voltage (V) and current (μA) are measured by a three-electrode cyclic voltametry using a measurement solution prepared by mixing the following materials. did.

Electrode: working electrode (glassy carbon electrode), counter electrode (platinum electrode) Reference electrode: silver nitrate electrode (0.1 mol / l AgNO ₃ -acetonitrile solution) Measurement solution Electrolyte: tetra-n-butylammonium perchlorate 0.1 mol Measurement substance: electron transporting agent 0.001 mol Solvent: CH ₂ Cl ₂ 1 liter As the above-mentioned electron accepting compound, for example, the following general formula (5)
Diphenoquinone derivative represented by the following general formula (6) benzoquinone derivative, naphthoquinone derivative, anthraquinone derivative, malononitrile derivative, thiopyran derivative, trinitrothioxanthone derivative, 3,4,
Among compounds having electron accepting properties such as fluorenone derivatives such as 5,7-tetranitro-9-fluorenone, dinitroanthracene derivatives, dinitroacridine derivatives, nitroantaraquinone derivatives, and dinitroanthraquinone derivatives, the oxidation-reduction potential is within the above range. Can be used.

[0030]

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Wherein R ^A , R ^B , R ^C , R ^D , R ^E ,
R ^F , R ^G and R ^H are the same or different and represent a hydrogen atom, an alkyl group, an aryl group, an aralkyl group, a cycloalkyl group, an alkoxy group or an amino group which may have a substituent. Among the electron accepting compounds exemplified above, the above general formula
A diphenoquinone derivative represented by (5) and the above general formula
It is preferable to use a compound belonging to the benzoquinone derivative represented by (6) and having a redox potential within the above range.

The alkyl group, aryl group and alkoxy group in the above general formulas (5) and (6) include the same groups as described above. Examples of the aralkyl group include groups such as benzyl, benzhydryl, trityl, and phenethyl. Examples of the cycloalkyl group include groups having 3 to 6 carbon atoms such as cyclopropyl, cyclobutyl, cyclopentyl, and cyclohexyl. Examples of the amino group which may have a substituent include, for example, amino group, monomethylamino, dimethylamino,
Examples include groups such as monoethylamino and diethylamino.

Among the electron-accepting compounds exemplified above, specific examples of the diphenoquinone derivative represented by the general formula (5) include, for example, 3,5-dimethyl-derivative represented by the following formula (5-1).
3 ', 5'-di (t-butyl) -4,4'-diphenoquinone (redox potential -0.86 V), 3,3', 5,5'- represented by the following formula (5-2) Tetra (t-butyl)-
4,4'-diphenoquinone (redox potential -0.94
V), and 3,3′-dimethyl-5,5′-di (t-
Butyl) -4,4'-diphenoquinone and 3,5'-dimethyl-3 ', 5-di (t-butyl) -4,4'-diphenoquinone.

[0034]

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As a specific example of the benzoquinone derivative represented by the general formula (6), for example,
-Benzoquinone (redox potential -0.81 V), formula (6-
2,2-di (t-butyl) -p-benzoquinone (redox potential -1.31 V) represented by 2).

[0036]

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The electron-accepting compounds exemplified above can be used alone or in combination of two or more. Next, various materials used for the electrophotographic photosensitive member of the present invention will be described. <Charge generator> As the charge generator used in the present invention, for example, powders of inorganic photoconductive materials such as selenium, selenium-tellurium, selenium-arsenic, cadmium sulfide, amorphous silicon, phthalocyanine pigments, naphthalocyanine pigments , Perylene pigments, bisazo pigments, dithioketopyrrolopyrrole pigments, squaraine pigments, azo pigments, trisazo pigments, indigo pigments, azurenium pigments, cyanine pigments, anthanthrone pigments, triphenylmethane pigments Pigments, sullen pigments, toluidine pigments, pyrazoline pigments, quinacridone pigments and the like. The charge generating agents exemplified above are used alone or in combination of two or more so that the photoreceptor has an absorption wavelength in a desired region.

Among the charge generation agents exemplified above, in particular, in a digital optical image forming apparatus such as a laser beam printer or a facsimile using a light source such as a semiconductor laser, a photosensitive member having a sensitivity in a wavelength region of 700 nm or more is used. For this reason, phthalocyanine pigments such as metal-free phthalocyanine and titanyl phthalocyanine are preferably used.

On the other hand, an analog optical system image forming apparatus such as an electrostatic copying machine using a white light source such as a halogen lamp requires a photosensitive member having sensitivity in the visible region.

[0040]

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(Wherein, R ^J and R ^K are the same or different and represent a substituted or unsubstituted alkyl group, cycloalkyl group, aryl group, alkanoyl group or aralkyl group having 18 or less carbon atoms). The perylene pigments and bisazo pigments used are preferably used. In the above general formula, as the substituted or unsubstituted alkyl group having 18 or less carbon atoms, in addition to the aforementioned alkyl group having 1 to 6 carbon atoms, octyl, nonyl, decyl, dodecyl, tridecyl, pentadecyl, And groups such as octadecyl.
Examples of the cycloalkyl group, the aryl group, and the aralkyl group include the same groups as described above. Examples of the alkanoyl group include groups such as formyl, acetyl, propionyl, butyryl, pentanoyl, and hexanoyl. Further, the alkyl group, cycloalkyl group, aryl group and aralkyl group may have a substituent such as an alkyl group at an arbitrary position.

<Hole transport agent> Examples of the hole transport agent used in the present invention include benzidine derivatives, phenylenediamine derivatives, naphthylenediamine derivatives, phenanthrylenediamine derivatives, 2,5-di (4-methylamino) derivatives. Oxadiazole derivatives such as phenyl) -1,3,4-oxadiazole, styryl derivatives such as 9- (4-diethylaminostyryl) anthracene, carbazole derivatives such as polyvinylcarbazole, organic polysilane compounds, 1-phenyl-3- Pyrazoline derivatives such as (p-dimethylaminophenyl) pyrazoline, hydrazone derivatives, triphenylamine derivatives, indole derivatives, oxazole derivatives, isoxazole derivatives, thiazole derivatives, thiadiazole derivatives, imidazole derivatives, pyrazole derivatives, Riazor derivatives and the like can be used.

<Electron Transport Agent> In the photoreceptor of the present invention, various electron transport agents may be used in combination with the quinone derivative represented by the general formula (1). Such electron transporting agents include, for example, benzoquinone derivatives, diphenoquinone derivatives, naphthoquinone derivatives, anthraquinone derivatives, malononitrile derivatives, thiopyran derivatives, tetracyanoethylene, 2,4,8-trinitrothioxanthone, 2,2
Fluorenone derivatives such as 4,7-trinitro-9-fluorenone, dinitrobenzene, dinitroanthracene,
Examples include various electron-withdrawing compounds such as dinitroacridine, nitroanthraquinone, dinitroanthraquinone, succinic anhydride, maleic anhydride, and dibromomaleic anhydride.

<Binder Resin> As the binder resin for dispersing the above components, various resins conventionally used in the photosensitive layer can be used. For example, styrene-butadiene copolymer, styrene-acrylonitrile copolymer,
Styrene-maleic acid copolymer, acrylic copolymer, styrene-acrylic acid copolymer, polyethylene, ethylene-vinyl acetate copolymer, chlorinated polyethylene, polyvinyl chloride, polypropylene, ionomer, vinyl chloride-
Thermoplastic resins such as vinyl acetate copolymer, polyester, alkyd resin, polyamide, polyurethane, polycarbonate, polyarylate, polysulfone, diallyl phthalate resin, ketone resin, polyvinyl butyral resin, polyether resin, polyester resin; silicone resin, epoxy resin , A phenol resin, a urea resin, a melamine resin, other thermosetting resins having a cross-linking property, and resins such as a photo-curing resin such as an epoxy acrylate and a urethane-acrylate.

In the photosensitive layer, in addition to the above components, various conventionally known additives such as an antioxidant, a radical scavenger, a singlet quencher, and an ultraviolet absorbing agent may be used as long as the electrophotographic characteristics are not adversely affected. Agents, softeners, plasticizers, surface modifiers, extenders, thickeners, dispersion stabilizers, waxes, acceptors, donors, and the like.
Further, in order to improve the sensitivity of the photosensitive layer, a known sensitizer such as terphenyl, halonaphthoquinones, acenaphthylene and the like may be used in combination with the charge generator.

The single-layer type photoreceptor of the present invention has a general formula
The quinone derivative (electron transporting agent) represented by (1) and / or (2), a charge generating agent, a binder resin, and, if necessary, a hole transporting agent are dissolved or dispersed in an appropriate solvent to obtain It is formed by applying the applied coating liquid on a conductive substrate and drying. In the single-layer type photoreceptor, the charge generator is
The amount may be 0.1 to 50 parts by weight, preferably 0.5 to 30 parts by weight, based on 100 parts by weight of the binder resin.
The electron transport agent is 5 to 10 parts by weight based on 100 parts by weight of the binder resin.
0 parts by weight, preferably 10 to 80 parts by weight. The hole transporting agent may be blended at a ratio of 5 to 500 parts by weight, preferably 25 to 200 parts by weight, based on 100 parts by weight of the binder resin. When the electron transporting agent and the hole transporting agent are used in combination, the total amount of the electron transporting agent and the hole transporting agent is 20 to 100 parts by weight of the binder resin.
The amount is suitably 500 parts by weight, preferably 30 to 200 parts by weight. When the electron-accepting compound is contained in the single-layer type photosensitive layer, the amount of the electron-accepting compound is 0.1 to 40 parts by weight, preferably 0.5 to 40 parts by weight, based on 100 parts by weight of the binder resin.
It is appropriate to mix in 20 parts by weight.

The thickness of the photosensitive layer in the single-layer type photosensitive member is 5 to 5.
It is 100 μm, preferably 10 to 50 μm. The laminated photoreceptor of the present invention first forms a charge generation layer containing a charge generation agent on a conductive substrate by means such as vapor deposition or coating, and then forms a general formula on the charge generation layer.
It is prepared by applying a coating liquid containing the quinone derivative (electron transporting agent) represented by (1) and / or (2) and a binder resin, and then drying to form a charge transporting layer.

In the above-mentioned laminated type photoreceptor, the charge generating agent and the binder resin constituting the charge generating layer can be used in various ratios, and the charge generating agent is added to 100 parts by weight of the binder resin. 5 to 1000 parts by weight, preferably 30 to 50 parts
It is appropriate to mix at a ratio of 0 parts by weight. When the charge generating layer contains a hole transporting agent, the proportion of the hole transporting agent is suitably from 10 to 500 parts by weight, preferably from 50 to 200 parts by weight, based on 100 parts by weight of the binder resin. .

The electron transporting agent and the binder resin constituting the charge transporting layer can be used in various ratios within a range that does not hinder charge transport and a range that does not crystallize. An electron transporting agent is added to 100 parts by weight of the binder resin so that the generated charges can be easily transported.
It is suitable to mix at a ratio of from 500 to 500 parts by weight, preferably from 25 to 200 resin. When the charge-transporting layer contains an electron-accepting compound, the proportion of the electron-accepting compound is 0.1 to 40 parts by weight, preferably 0.5 to 20 parts by weight, based on 100 parts by weight of the binder resin. Is appropriate.

The thickness of the photosensitive layer in the laminated photoreceptor is such that the charge generation layer has a thickness of about 0.01 to 5 μm, preferably 0.1 to 5 μm.
The thickness is about 3 μm, and the thickness of the charge transport layer is about 2 to 100 μm, preferably about 5 to 50 μm. In the case of a single-layer type photoreceptor, between the conductive substrate and the photosensitive layer, and in the case of the laminated type photoreceptor, between the conductive substrate and the charge generating layer, between the conductive substrate and the charge transport layer, or A barrier layer may be formed between the generation layer and the charge transport layer as long as the characteristics of the photoreceptor are not impaired. Further, a protective layer may be formed on the surface of the photoconductor.

As the conductive substrate on which the photosensitive layer is formed, various materials having conductivity can be used.
For example, iron, aluminum, copper, tin, platinum, silver, vanadium, molybdenum, chromium, cadmium, titanium, nickel, palladium, indium, stainless steel, brass and other simple metals, and plastic materials on which the above metals are deposited or laminated, Glasses coated with aluminum iodide, tin oxide, indium oxide, and the like can be given.

The conductive substrate may be in the form of a sheet, a drum, or the like, depending on the structure of the image forming apparatus to be used. The substrate itself has conductivity or the surface of the substrate is conductive. What is necessary is just to have the property. The conductive substrate preferably has a sufficient mechanical strength when used. When the photosensitive layer is formed by a coating method, a charge generating agent, a charge transporting agent, a binder resin, and the like described above, together with a suitable solvent, may be used in a known manner, for example, a roll mill, a ball mill, an attritor, a paint shaker, or What is necessary is just to disperse and mix using a sonic disperser or the like to prepare a dispersion, apply it by a known means, and dry it.

As the solvent for preparing the dispersion, various organic solvents can be used, for example, alcohols such as methanol, ethanol, isopropanol and butanol; and aliphatic hydrocarbons such as n-hexane, octane and cyclohexane. Hydrogen; aromatic hydrocarbons such as benzene, toluene and xylene; halogenated hydrocarbons such as dichloromethane, dichloroethane, chloroform, carbon tetrachloride and chlorobenzene; ethers such as dimethyl ether, diethyl ether, tetrahydrofuran, ethylene glycol dimethyl ether and diethylene glycol dimethyl ether Ketones such as acetone, methyl ethyl ketone and cyclohexanone; esters such as ethyl acetate and methyl acetate; dimethyl formaldehyde, dimethyl formamide, dimethyl sulfone Kishido and the like. These solvents are used alone or in combination of two or more.

Further, in order to improve the dispersibility of the charge transporting agent and the charge generating agent and the smoothness of the surface of the photosensitive layer, a surfactant,
A leveling agent or the like may be used.

[0055]

The present invention will be described below with reference to Synthesis Examples, Examples and Comparative Examples. <Synthesis of Quinone Derivative> Synthesis Example 1 (Synthesis of Quinone Derivative (1-1)) Methyl-1,4-benzoquinone 3.0 g (24.6 mmol), acetic acid 100 ml, copper (II) acetate monohydrate 2 .5g
(12.5 mmol) and 3.5 g of β-naphthol
(24.3 mmol) was added to the reaction vessel and stirred at 50 ° C. for 3 hours. After the reaction, the reaction solution was poured into water, and the organic component was extracted with chloroform. After washing with water, the chloroform component was distilled off, and the residue was purified with a silica gel column (developing solvent: chloroform) to give an intermediate 1. represented by the following formula (4-1).
1 g (16.7% yield) was obtained.

[0056]

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Then, 0.5 g of the above intermediate (4-1) (1.
9 mmol), 0.25 g (1.9 mmol) of copper chloride and 20 ml of pyridine were added to the reaction vessel and refluxed for 2 hours. After the reaction, the reaction solution was poured into a 1N-hydrochloric acid aqueous solution, and the organic component was extracted with chloroform. After washing with water, chloroform was distilled off, and the residue was purified with a silica gel column (developing solvent: chloroform) to obtain 0.12 g (yield: 24.1%) of the quinone derivative represented by the above formula (1-1). Was.

Melting point: 251 ° C. Mass spectrum: [M ⁺ ] = 262 Synthesis Example 2 (Synthesis of quinone derivative (1-2)) 0.1 g of quinone derivative (1-1) obtained in Synthesis Example 1 (0.1 g).
38 mmol), 10 ml of methanol and 0.01 g of zinc chloride were added to the reaction vessel, and the mixture was stirred at 50 to 60 ° C for 5 hours. After the reaction, the reaction solution was poured into water, and the organic component was extracted with chloroform. After washing with water, chloroform is distilled off.
The residue was purified with a silica gel column (developing solvent: chloroform) to obtain a quinone derivative represented by the above formula (1-2).
7 g (63% yield) were obtained.

Melting point: 254 ° C. <Production of electrophotographic photoreceptor> Example 1 (single-layer type photoreceptor for digital light source) 5 parts by weight of a charge generator, 50 parts by weight of a hole transporting agent, 30 parts by weight of an electron transporting agent and Binder resin (polycarbonate) 10
0 parts by weight and 800 parts by weight of a solvent (tetrahydrofuran) were mixed and dispersed in a ball mill for 50 hours to prepare a coating solution for a single-layer type photosensitive layer. Next, this coating solution was applied on a conductive substrate (aluminum pipe) by dip coating, and dried with hot air at 100 ° C. for 60 minutes to form a film having a thickness of 15 to 2 μm.
A single-layer type photoreceptor having a 0 μm photosensitive layer was produced.

In the above photoreceptor, a titanyl phthalocyanine pigment (PcTiO) is used as a charge generating agent, a benzidine derivative represented by the following formula (B) is used as a hole transporting agent, and the above formula (1- The quinone derivatives represented by 1) were used.

[0061]

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Comparative Example 1 A single-layer type photoreceptor for a digital light source was manufactured in the same manner as in Example 1, except that the diphenoquinone derivative represented by the formula (5-1) was used as the electron transporting agent. Example 2 (Laminated photoreceptor for digital light source) 100 parts by weight of a charge generating agent and 100 parts by weight of a binder resin (polyvinyl butyral) were used as a solvent (tetrahydrofuran).
The mixture was mixed and dispersed in a ball mill together with 2,000 parts by weight for 50 hours to prepare a coating solution for a charge generation layer. Next, this coating solution was applied onto a conductive substrate (aluminum tube) by dip coating, and dried with hot air at 100 ° C. for 60 minutes to form a 1 μm-thick charge generating layer.

Next, 100 parts by weight of the electron transport agent and 100 parts by weight of the binder resin (polycarbonate) were mixed and dispersed in a ball mill for 50 hours together with 800 parts by weight of the solvent (toluene) to prepare a coating liquid for the charge transport layer. did. Then
This coating solution was applied on the charge generation layer by dip coating, and dried with hot air at 100 ° C. for 60 minutes to form a film having a thickness of 20 μm.
m of the charge transport layer was formed to obtain a laminated photoreceptor.

In the above photoreceptor, a metal-free phthalocyanine pigment (PcH ₂ ) was used as a charge generating agent. The same electron transporting agent as in Example 1 was used. Comparative Example 2 A laminated photoreceptor for a digital light source was manufactured in the same manner as in Example 2 except that the diphenoquinone derivative represented by the above formula (5-1) was used as the electron transporting agent.

Example 3 (Single-layer type photoreceptor for analog light source) As a charge generating agent, the following formula (Pe) was used.

[0066]

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A single-layer type photoreceptor for an analog light source was produced in the same manner as in Example 1 except that the perylene pigment represented by the formula (1) was used. Comparative Example 3 A single-layer photoreceptor for an analog light source was produced in the same manner as in Example 3, except that the diphenoquinone derivative represented by the above formula (5-1) was used as the electron transporting agent.

Comparative Example 4 A single-layer photosensitive member for an analog light source was manufactured in the same manner as in Example 3 except that the electron transporting agent was not used. Example 4 (Laminated photoreceptor for analog light source) A laminated photoreceptor for analog light source was prepared in the same manner as in Example 2 except that a perylene pigment represented by the formula (Pe) was used as a charge generating agent. Body manufactured.

Comparative Example 5 A laminated photoreceptor for an analog light source was produced in the same manner as in Example 4, except that the diphenoquinone derivative represented by the above formula (5-1) was used as the electron transporting agent. Examples 5 to 8 (Single-layer type photoreceptor for digital light source) 5 parts by weight of a charge generating agent, 50 parts by weight of a hole transporting agent, 30 parts by weight of an electron transporting agent, 10 parts by weight of an electron accepting compound, and a binder resin (polycarbonate) ) 100 parts by weight together with 800 parts by weight of a solvent (tetrahydrofuran) in a ball mill 5
The mixture was mixed and dispersed for 0 hour to prepare a coating solution for a single-layer type photosensitive layer. Next, this coating solution is applied on a conductive substrate (aluminum tube) by dip coating,
After drying with hot air for 1 minute, a single-layer photoreceptor having a photosensitive layer thickness of 15 to 20 μm was produced.

In the above photoreceptor, metal-free phthalocyanine (H ₂ Pc) is used as the charge generating agent, and the above formula (B) is used as the hole transporting agent.
A benzidine derivative represented by the formula
Each of the quinone derivatives represented by (1-1) was used. As the electron accepting compound, a benzoquinone derivative represented by the above formula (6-1) or (6-2) or a diphenoquinone derivative represented by the above formula (5-1) or (5-2) was used.

Comparative Example 6 A diphenoquinone derivative represented by the above formula (5-1) was used in place of the quinone derivative represented by the above formula (1-1) as an electron transporting agent. A single-layer type photoreceptor for a digital light source was manufactured in the same manner as in Example 5 except that no compounding was performed.

Comparative Example 7 A single-layer photosensitive member for a digital light source was produced in the same manner as in Example 5, except that the electron transporting agent and the electron accepting compound were not blended. The following electrical property test (A) was conducted for the above Examples 1-2, 5-8 and Comparative Examples 1-2, 6-7, and the following electrical property test was conducted for the above Examples 3-4 and Comparative Examples 3-5. By performing (B), the electrical characteristics of each photoconductor were evaluated.

Electric Property Test (A) (Electrical Property Test of Photoreceptor for Digital Light Source) A voltage is applied to the surface of the photoreceptor by using a drum sensitivity tester manufactured by GENTEC, and the surface is +700.
Was charged. Next, as an exposure light source, a wavelength of 780 nm (half-width 20 nm, light intensity 16 μW / c) extracted from white light of a halogen lamp using a band-pass filter.
m ² ), the surface of the photoreceptor is irradiated with the monochromatic light (irradiation time: 80 milliseconds), and the surface potential at the time when 330 milliseconds have elapsed from the start of the exposure is determined by the residual potential V _L. It was measured as (unit: V).

Electrical Characteristics Test (B) (Electrical Characteristics Test of Photoconductor for Analog Light Source) White light (light intensity 147) of a halogen lamp as an exposure light source
μW / cm ² ), and the residual potential V _L (unit: V) was measured in the same manner as in the above-mentioned electrical property test (A) except that the irradiation time was set to 50 milliseconds. Note that the residual potential _VL is
The smaller the value, the better the sensitivity.

Table 1 shows the types of the charge generating agent, the hole transporting agent, the electron transporting agent and the electron accepting compound used in Examples 1 to 8 and Comparative Examples 1 to 7, together with the test results of the electrical characteristics. In the tables below, the types of the charge generating agent, the hole transporting agent, the electron transporting agent, and the electron accepting compound are indicated by the numbers assigned to the respective compounds.

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[Table 1]

Example 9 (Single-layer type photoreceptor for digital light source) A digital light source was prepared in the same manner as in Example 1 except that the quinone derivative represented by the formula (1-2) was used as the electron transporting agent. Was produced. Example 10 (Laminated photoreceptor for digital light source) A laminated photoreceptor for digital light source was prepared in the same manner as in Example 2 except that the quinone derivative represented by the formula (1-2) was used as the electron transporting agent. Body manufactured.

Example 11 (Single-layer type photoreceptor for analog light source) The same procedure as in Example 3 was repeated except that the quinone derivative represented by the formula (1-2) was used as the electron transporting agent. Was produced. Example 12 (Laminated photoreceptor for analog light source) A laminated photoreceptor for analog light source was prepared in the same manner as in Example 4 except that the quinone derivative represented by the above formula (1-2) was used as the electron transporting agent. Body manufactured.

Examples 13 to 16 (single-layer type photoreceptor for digital light source) Except that the quinone derivative represented by the above formula (1-2) was used as the electron transporting agent, the same procedures as in Examples 5 to 8 were carried out. A single-layer photoreceptor was manufactured. The following electrical property test (A) was performed on the above Examples 9 to 10 and 13 to 16, and the above Examples 11 to 1 were tested.
2 was subjected to the following electrical property test (B) to evaluate the electrical properties of each photoconductor.

Table 2 shows the types of the charge generating agent, the hole transporting agent, the electron transporting agent, and the electron-accepting compound used in Examples 9 to 16 together with the test results of the electrical characteristics.

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[Table 2]

As is clear from Tables 1 and 2, the electrophotographic photoreceptors of Examples 1 to 16 using the quinone derivative represented by the general formula (1) as the electron transporting agent corresponded to Comparative Examples 1 to 7
The photoconductor low residual potential V _L compared to the sensitivity is excellent.

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Since the quinone derivative (1) of the present invention has a high charge transporting ability (electron transporting ability), it can be suitably used as an electron transporting agent in electrophotographic photoreceptors, solar cells, electroluminescent devices and the like. . Further, the electrophotographic photoreceptor of the present invention has a high sensitivity because it has a photosensitive layer containing a quinone derivative represented by the general formula (1). Therefore, the electrophotographic photoreceptor of the present invention has a specific function and effect that contributes to speeding up and improving performance of various image forming apparatuses such as an electrostatic copying machine and a laser beam printer.

[Brief description of the drawings]

FIG. 1 is a graph showing a relationship between a pulling voltage (V) and a current (μA) for obtaining an oxidation-reduction potential of an electron-accepting compound.

Claims (3)

[Claims] [Claim 1] General formula (1): (Wherein R ¹ and R ² are the same or different and each represent a hydrogen atom, an alkyl group or an alkoxy group, and R ³ represents a hydrogen atom, an alkyl group, an aryl group or an alkoxy group, provided that R ¹ and R ² Is not a hydrogen atom at the same time.). 2. An electrophotographic photoreceptor having a photosensitive layer provided on a conductive substrate, wherein the photosensitive layer has the general formula (1) according to claim 1.
An electrophotographic photosensitive member containing a quinone derivative represented by the formula: 3. The method according to claim 1, wherein the photosensitive layer comprises a quinone derivative represented by the general formula (1) having an oxidation-reduction potential of -0.8 to-
3. The electrophotographic photoreceptor according to claim 2, comprising an electron accepting compound having a voltage of 1.4V.