JPH051938B2 - - Google Patents

Description

[Detailed description of the invention]

<Industrial Application Field> The present invention relates to an electrophotographic photoreceptor. Specifically, the present invention relates to a highly sensitive electrophotographic photoreceptor having a photosensitive layer containing an organic photoconductive substance. <Prior art> Traditionally, inorganic photoconductive materials such as selenium, cadmium sulfide, and zinc oxide have been widely used in the photosensitive layer of electrophotographic photoreceptors, but in recent years, inorganic photoconductive materials such as polyvinyl carbazole have been widely used. Research on the use of organic photoconductive substances in the photosensitive layer of electrophotographic photoreceptors has progressed, and some of them have been put into practical use. Organic photoconductive materials have advantages over inorganic materials, such as being lightweight, easy to form a film, and easy to manufacture photoreceptors. Despite having such many advantages, organic photoconductive materials have not been widely adopted as electrophotographic photoreceptors because they are inferior to inorganic materials in terms of sensitivity and durability. <Problems to be Solved by the Invention> Therefore, the present inventors have conducted intensive research on organic photoconductive materials that provide electrophotographic photoreceptors with high sensitivity and high durability. <Means for Solving the Problems> As a result, it was discovered that a specific azo compound is suitable, and the present invention was achieved. That is, the gist of the present invention resides in an electrophotographic photoreceptor characterized by having a photosensitive layer containing an azo compound represented by the following general formula () on a conductive support. (In the above general formula (), Cp represents a coupler residue selected from the following). (In the formula, X represents an organic group that is condensed with benzene ring A to form a naphthalene ring, anthracene ring, carbazole ring, benzocarbazole ring, or dibenzofuran ring together with benzene ring A, and R ¹ is a hydrogen atom, an alkyl group, or represents a phenyl group,
R ² represents an alkyl group, a phenyl group, a naphthyl group, or a dibenzofuranyl group, each of which is 1 selected from an alkyl group, an alkoxy group, a halogen atom, a nitro group, an amino group, and a cyano group.
It may be substituted with any of the above substituents. ) (In the formula, R ³ represents an alkyl group, a benzyl group, or a phenyl group, and any of these may be substituted with one or more substituents selected from an alkoxy group, a halogen atom, and a hydroxy group.) (In the formula, Z represents a divalent group of an aromatic hydrocarbon or a divalent group of a heterocycle containing a nitrogen atom in the ring, and these are all alkyl groups, halogen atoms, nitro groups, amino groups, dialkyl groups. The present invention will be described in detail below.The azo compound contained in the photosensitive layer of the electrophotographic photoreceptor of the present invention is It is represented by the general formula (). In the general formula (), Cp is shown below)~)
Represents a coupler residue selected from In the formula, show. R ¹ is a hydrogen atom, an alkyl group (e.g., methyl group, ethyl group, propyl group, isopropyl group, butyl group, sec-butyl group, amyl group, hexyl group,
Octyl group, 2-ethylhexyl group, nonyl group,
(octadecyl group, benzyl group, etc.) or phenyl group. R ² is an alkyl group optionally substituted with one or more substituents selected from an alkyl group, an alkoxy group, a halogen atom, a nitro group, a dialkylamino group, and a cyano group (e.g., a methyl group, an ethyl group,
Propyl group, isopropyl group, butyl group, sec-
Butyl group, amyl group, hexyl group, octyl group,
2-ethylhexyl group, nonyl group, octadecyl group, benzyl group, etc.), phenyl group, naphthyl group or dibenzofuranyl group (e.g. phenyl group,
tolyl group, xylyl group, chlorophenyl group, dichlorophenyl group, trichlorophenyl group, bromophenyl group, dibromophenyl group, tribromophenyl group, methoxyphenyl group, ethoxyphenyl group, butoxyphenyl group, nitrophenyl group,
cyanophenyl group, hydroxyphenyl group, carboxyphenyl group, N,N-dimethylaminophenyl group, N,N-diethylaminophenyl group,
N,N-dibenzylaminophenyl group, α-naphthyl group, β-naphthyl group, dibenzofuranyl group,
methoxybenzofuranyl group, etc.). In the formula, R ³ is an alkyl group, an alkoxy group,
1 selected from halogen group and hydroxyl group
Alkyl groups that may be substituted with the above substituents (e.g. methyl group, ethyl group, propyl group, isopropyl group, butyl group, sec-butyl group, isobutyl group, hexyl group, cyclohexyl group, octyl group, 2-ethylhexyl group) group, methoxymethyl group, ethoxymethyl group, 2-methoxyethyl group,
2-ethoxyethyl group, 2-hydroxyethyl group, 2-hydroxypropyl group, 2-chloroethyl group, 3-chloropropyl group, 4-chlorobutyl group, etc.), benzyl group (e.g. methylbenzyl group,
ethylbenzyl group, propylbenzyl group, isopropylbenzyl group, methoxybenzyl group, ethoxybenzyl group, chlorobenzyl group, bromobenzyl group), or phenyl group (e.g. phenyl group, tolyl group, xylyl group, chlorophenyl group,
(dichlorophenyl group, bromophenyl group, dibromophenyl group, methoxyphenyl group, ethoxyphenyl group, ethyl phenyl group, hydroxyphenyl group, etc.). In the formula, Z is an aromatic hydrocarbon divalent group which may be substituted with one or more substituents selected from an alkyl group, a halogen group, a nitro group, an amino group, a dialkylamino group, and a hydroxyl group, or a nitrogen atom Indicates a heterocyclic divalent group containing in the ring. Examples of divalent groups of aromatic hydrocarbons include divalent groups of monocyclic aromatic hydrocarbons such as o-phenylene, o-naphthylene group, peri-naphthylene group, 1,2-anthraquinonylene group, 9,10 - Divalent groups of condensed polycyclic aromatic hydrocarbons such as phenanthrylene groups, and the like. In addition, as a heterocyclic divalent group containing a nitrogen atom in the ring, for example, 3,4-pyrazoledilyl group,
2,3-pyridinediyl group, 4,5-pyrimidinediyl group, 6,7-indazolediyl group, 5,
2 of a heterocyclic ring containing a 5- to 10-membered nitrogen atom, preferably 2 or less nitrogen atoms, such as a 6-benzimidazolediyl group and a 6,7-quinolinediyl group;
Examples include valence groups. When considering sensitivity and durability, o-phenylene group, o-naphthylene group, peri-naltylene group,
2,3-pyridinediyl group, 4,5-pyrimidinediyl group, and especially o-phenylene group and o-naphthylene group are preferred. In the present invention, the divalent group of aromatic hydrocarbon may have the following substituents. Examples of such substituents include alkyl groups such as methyl group, ethyl group, propyl group, 1-propyl group, n-butyl group, sec-butyl group, and n-hexyl group; fluorine atom, chlorine atom, bromine atom, etc. halogen atom; examples include nitro group and hydroxyl group. Specific examples of the azo compound useful in the present invention represented by the general formula () include those having the structural formula shown in Table 1.

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【table】

[Table] The azo compound of the present invention is, for example, a coupling component represented by the following general formula (-A) and/or (-B).

【formula】

[Formula] (In the formula, Z has the same meaning as in the above general formula ().) and the formula () It can be easily synthesized by a coupling reaction of a diamine represented by the formula with a tetrazonium salt. Such coupling reaction is carried out according to a known method, usually in water and/or an organic solvent such as dimethyl sulfoxide, N-methylpyrrolidone, N,N-dimethylformamide, etc., at a reaction temperature of 30°C or less for about 1 to 10 hours. Just let it happen. Compounds containing coupler residues () and () can be synthesized in a similar manner. The coupler components represented by general formulas (-A) and (-B) can be prepared by, for example, combining 3-hydroxynaphthalic anhydride () and aromatic diamine () in a solvent such as acetic acid according to the following reaction formula (). It is obtained as a mixture by heating and dehydration condensation (see JP-A-57-176055). Reaction formula () The diamine represented by the above formula () can be easily produced by a known method, for example, according to the reaction formula shown below. The azo compound of the present invention can be obtained by the above-mentioned method, and the coupler component has the above-mentioned general formula (
When using a mixture of -A) and (-B), the following general formulas (-A), (-B), (-C)
It is obtained as a mixture of isomers represented by In the present invention, these mixtures can be used as they are. The electrophotographic photoreceptor of the present invention has a photosensitive layer containing one or more azo compounds represented by the above general formula (). Various forms of photosensitive layers are well known, and the photosensitive layer of the electrophotographic photoreceptor of the present invention may be any of them. Generally, the following types of photosensitive layers can be used. A photosensitive layer made of an azo compound A photosensitive layer containing an azo compound dispersed in a binder A photosensitive layer containing an azo compound dispersed in a well-known charge transfer medium The photosensitive layer of ~ above serves as a charge generation layer, and a well-known charge transfer medium is added to the photosensitive layer. The azo compound represented by the general formula () is:
When it absorbs light, it generates charge carriers with extremely high efficiency. Although the generated carriers can be transferred using an azo compound as a medium, it is preferable to use a known charge transfer medium as a medium. From this point of view, photosensitive layers in the form of and are particularly preferred, and the highest performance can be obtained with the form of.
In this case, the charge generation layer may be formed by applying a coating solution obtained by dissolving or dispersing an azo compound represented by the general formula () in an appropriate solvent alone or in a binder polymer onto the conductive support. ,
Obtained by drying. Butylamine, butylamine,
Basic solvents such as ethylenediamine; ethers such as tetrahydrofuran, methyltetrahydrofuran, 1,4-dioxane, and diethylene glycol dimethyl ether; ketones such as methyl ethyl ketone and cyclohexanone; aromatic hydrocarbons such as toluene and xylene; N,N-dimethylformamide, Aprotic polar solvents such as acetonitrile, N-methylpyrrolidone, dimethylsulfoxide;
Examples include alcohols such as methanol, ethanol, and isopropanol; esters such as ethyl acetate, methyl formate, and methyl cellosolve acetate; and chlorinated hydrocarbons such as dichloroethane and chloroform. These solvents can be used alone or in combination of two or more. When using a binder polymer, it is desirable to use one that dissolves the polymer. As the binder polymer, polymers and copolymers of vinyl compounds such as styrene, vinyl acetate, acrylic ester, and methacrylic ester;
Examples include polyester, polycarbonate, polysulfone, polyvinyl butyral, phenoxy resin, cellulose ester, cellulose ether, urethane resin, and epoxy resin. The amount of binder polymer used is usually in the range of 0.1 to 5 times the weight of the azo compound. In addition, the azo compound has a thickness of 1 μm in the binder.
It is preferable to make it exist in the following fine particle state.
The thickness of the charge generation layer is usually several μm or less, especially 1 μm.
The following are preferred. As the conductive support on which the charge generation layer is applied, any of those employed in well-known electrophotographic photoreceptors can be used. Specific examples include metal drums and sheets made of aluminum, copper, etc., and laminates and vapor deposits of these metal foils. Further examples include plastic films, plastic drums, paper, paper tubes, etc., which are coated with a conductive substance such as metal powder, carbon black, copper iodide, or polymer electrolyte together with a suitable binder to conductivity treatment. In addition, metal powder, carbon black,
Examples include plastic sheets and drums that contain conductive substances such as carbon fibers and are made conductive. A charge transfer layer is formed by stacking on the charge generation layer. Conversely, a charge transfer layer may be formed on a conductive support and a charge generation layer may be laminated on top of the charge transfer layer, but since the thickness of the charge generation layer is usually thin, it is difficult to protect the charge generation layer from wear and dirt. The former type is often used for this purpose. The charge transport layer is a layer that transports charge carriers generated in the charge generation layer, and contains a charge carrier transport medium. Charge carrier transfer media are generally classified into two types: electron transfer media and hole transfer media, and both can be used in the photosensitive layer of the photoreceptor of the present invention, and a mixture thereof can also be used. As an electron transfer medium, an electron-withdrawing compound having an electron-withdrawing group such as a nitro group, a cyano group, or an ester group, such as 2,4,7-trinitrofluorenone, 2,4,5,7-tetranitrofluorenone, etc. Examples include nitrated fluorenone or tetracyanoquinodimethane. In addition, electron-donating organic photoconductive compounds can be used as hole transfer media, such as heterocyclic compounds such as carbazole, indole, imidazole, oxazole, thiazole, oxadiazole, pyrazole, pyrazoline, thiadiazole, aniline derivatives, and hydrazine derivatives. , hydrazone, or polymers having a group consisting of these compounds in the main chain or side chain (polyvinylcarbazole, polyglycidylcarbazole), and the like. Among these, especially the following general formula [] (In the above formula, R ⁴ represents an alkyl group, a substituted alkyl group, or an aralkyl group, and R ⁵ represents an alkyl group, an allyl group, a substituted alkyl group, a phenyl group,
It represents a naphthyl group or an aralkyl group, and Z ¹ represents a hydrogen atom, an alkyl group, an alkoxy group or a halogen atom. ) or the following general formula [] (In the above formula, X ¹ , Y ¹ and Z ² are hydrogen atoms,
Represents a lower alkyl group, lower alkoxy group, phenoxy group or arylalkoxy group, R ⁶ represents a hydrogen atom, lower alkyl group, allyl group, phenyl group or aralkyl group, m and l are 1
or 2, and p represents 0 or 1. )
It is preferable to use the hydrazone compounds represented by the following formulas alone or in combination. When the charge carrier transfer medium is a low-molecular compound, the charge transfer layer is formed in a state in which it is dissolved in a binder polymer. The charge carrier transfer medium is usually 0.2 to 1.5 times the weight of the binder polymer,
Preferably, it is used in an amount of 0.3 to 1.2 times by weight. As the binder polymer, a polymer similar to that used for the charge generation layer is used, and it is dissolved in a solvent together with the charge carrier transfer medium to prepare a coating solution, which is coated and dried to form the charge transfer layer. The thickness of the charge transfer layer is 5 to 50 μm, preferably 10 to 30 μm. Of course, the photosensitive layer of the electrophotographic photoreceptor of the present invention may contain a known sensitizer. Suitable sensitizers include Lewis acids and dyes that form charge transfer complexes with organic photoconductive materials. Examples of Lewis acids include chloranil, 2,3-dichloro-
1,4-naphthoquinone, 2-methylanthraquinone, 1-nitroanthraquinone, 1-chloro-5
- quinones such as nitroanthraquinone, 2-chloroanthraquinone, phenanthrenequinone,
Aldehydes such as 4-nitrobenzaldehyde, 9-benzoylanthracene, indanedione, 3,5-dinitrobenzophenone, 3,3',
Ketones such as 5,5'-tetranitrobenzophenone, acid anhydrides such as phthalic anhydride and 4-chloronaphthalic anhydride, tetracyanoethylene, terephthalalmalononitrile, 4-nitrobenzalmalononitrile, 4- (p-nitrobenzoyloxy)
Cyano compounds such as benzalmalononitrile; 3-
Benzalphthalide, 3-(α-cyano-p-nitrobenzal)phthalide, 3-(α-cyano-p-
Examples include electron-withdrawing compounds such as phthalides such as (nitrobenzal)-4,5,6,7-tetrachlorophthalide. Examples of dyes include triphenylmethane dyes such as methyl violet, brilliant green, and crystal violet, thiazine dyes such as methylene blue, quinone dyes such as quinizarin, cyanine dyes, pyrylium salts, thiapyrylium salts, and benzopyrylium salts. It will be done. Furthermore, the photosensitive layer of the electrophotographic photoreceptor of the present invention may contain a well-known plasticizer in order to improve film formability, flexibility, and mechanical strength. Examples of the plasticizer include phthalate esters, phosphate esters, epoxy compounds, chlorinated paraffins, chlorinated fatty acid esters, aromatic compounds such as methylnaphthalene, and the like. It goes without saying that it may also have an adhesive layer, an intermediate layer, and a transparent insulating layer, if necessary. <Effects of the Invention> The photoreceptor using the azo compound of the present invention has high sensitivity and good color sensitivity, and when used repeatedly, there is little variation in sensitivity and chargeability, and there is little optical fatigue. It has extremely high durability. Furthermore, the photoreceptor of the present invention has a maximum spectral sensitivity wavelength of 600~
It is in the 650nm range and can be widely used in electrophotographic applications such as electrophotographic copying machines and photoreceptors for printers that use lasers, LEDs, OFT (Optical Fiber Tubes), etc. as light sources. <Examples> Next, the present invention will be explained in more detail with reference to production examples and examples, but the present invention is not limited to the following examples unless it exceeds the gist thereof. Production Example 1 (Synthesis of Compound 1-38 in Table 1) (1) Mix 16 parts of carbazole, 78 parts of nitrobenzene, and 12 parts of potassium hydroxide powder, heat in a water bath from room temperature to 80°C, and keep at the same temperature for 1 hour. ,moreover
After reacting at 100°C for 30 minutes, the resulting solution was allowed to stand overnight. The orange solid that precipitated the next day was collected, thoroughly washed with methanol, and then recrystallized from acetone. The yield was 14 parts, and the melting point was 209-210°. This crystal was found to be 9-(p-nitrophenyl)carbazole based on its melting point and infrared absorption spectrum. (2) 9-(p-nitrophenyl)carbazole 5
1 part was added to 500 parts of glacial acetic acid and dissolved by heating at 60°C, and then 3 parts of fuming nitric acid was added dropwise over 10 minutes.
After reacting at 60°C for 2 hours, the mixture was allowed to cool to room temperature, and the precipitated solid was collected and thoroughly washed with acetone.
The crystals obtained are pale yellow in color and have a melting point of
It was 265-266°. As a result of infrared absorption spectrum, NMR spectrum, and elemental analysis, this crystal was confirmed to be 9-(p-nitrophenyl)-3-nitrocarbazole. Yield is 4.7
It was hot at the club. Calculated values as C ₁₈ H ₁₁ N ₃ O ₄ : C64.86%, H3.30%, N12.60% Actual values: C64.94%, H3.36%, N12.67% (3) The above dinitrocarbazole 3 parts of tin chloride (35%) suspended in 200 parts of THF and 20 parts of tin chloride () at room temperature.
A solution of hydrochloric acid (36 parts) was added dropwise over 15 minutes. 60
The mixture was heated to ℃ and reacted at the same temperature for 15 hours, then cooled to room temperature, and the precipitated solid was taken and dissolved in 100 parts of water. This aqueous solution was filtered once, the liquid was neutralized with a 10% aqueous sodium hydroxide solution, the precipitated white solid was dried, and recrystallized from methanol to obtain 2 parts of white crystals. The infrared absorption spectrum and NMR spectrum indicate that this crystal is 9-(p-
It was confirmed that it was (aminophenyl)-3-aminocarbazole. Melting point: 115° (4) 1.4 parts of 9-(p-aminophenyl)-3-aminocarbazole was added to 20 parts of demineralized water, 6.2 parts of a 35% aqueous hydrochloric acid solution was added dropwise, and the mixture was stirred for 30 minutes. Sodium nitrite was added while keeping this reaction system at 0 to 5℃.
0.8 part of a saturated aqueous solution was added dropwise over 10 minutes.
After stirring at the same temperature for 30 minutes, 3.8 parts of a 42% hydroborofluoric acid aqueous solution was added dropwise, and the corresponding tetrazonium tetrafluoroborate salt was precipitated and filtered. The yellow tetrafluoroborate salt obtained was dissolved in 100 parts of dimethyl sulfoxide at room temperature, and 2-hydroxy and 5-hydroxy-7H
-Dissolve 3.1 parts of benzimidazo[2.1-a]benz[de]isoquinolin-7-one in 800 parts of dimethyl sulfoxide (cool to room temperature after heating and dissolving)
was added dropwise into the solution. While keeping the temperature of the reaction solution at around 20℃, a saturated methanol solution of 3.7 parts of sodium acetate is added dropwise to produce a pigment. After performing suspension purification using methanol, tetrahydrofuran, dimethylformamide, etc., it is washed with water and dried to form a bisazo pigment. Got 2.5 copies. From the elemental analysis values and infrared absorption spectrum, it was confirmed that this compound was a bisazo compound (mixture of isomers) represented by the following structural formula. and Elemental analysis values as C ₅₄ H ₂₉ N ₉ O ₄ Calculated values: C74.74%, H3.34%, N14.53% Actual values: C74.15%, H3.28%, N14.18% Production example 2 (Synthesis of Compound 1-26 in Table 1) Using N-methyl-3-hydroxynaphthalimide as a coupling component, coupling with the same tetrazo component as in Production Example 1 was carried out in the same manner as in Production Example 1. , a black-brown bisazo pigment was obtained. It was confirmed from elemental analysis and infrared absorption spectrum that this compound was a bisazo compound represented by the following structural formula. Elemental analysis values as C ₄₄ H ₂₇ N ₇ O ₆ Calculated values: C70.49%, H3.60%, N13.08% Actual values: C69.62%, H3.45%, N12.41% Production example 3 (Synthesis of compound 1-2 in Table 1) As a coupling component, naphthol AS-BO
Coupling with the same tetrazo component as in Production Example 1 was carried out using the same method as in Production Example 1 to obtain a deep red biszoa pigment. From the elemental analysis values and infrared absorption spectrum, it was confirmed that this compound was a bisazo compound represented by the following structural formula. Elemental analysis values as C ₆₀ H ₃₉ N ₇ O ₄ Calculated values: C78.18%, H4.23%, N10.64% Actual values: C77.75%, H4.27%, N10.05% Example 1 10 parts by weight of the bisazo compound synthesized in Production Example-1 (Table 1-No. 1-38), 5 parts by weight of phenoxy resin (PKHH manufactured by Union Carbide Co., Ltd.), and polyvinyl butyral resin (BH-3 manufactured by Sekisui Chemical Co., Ltd.). )
Add 100 parts by weight of tetrahydrofuran to 5 parts by weight,
Grinding and dispersion treatment was performed using a sand grind mill. The resulting dispersion of this azo compound is
It was applied with a film applicator onto an aluminum vapor-deposited layer deposited on a 100 μm polyester film to a dry film thickness of 0.6 g/m ² and then dried. N-
A solution of 80 parts by weight of ethylcarbazole-3-aldehyde diphenylhydrazone and 100 parts by weight of methacrylic resin (Dyanal BR-80 manufactured by Mitsubishi Rayon Co., Ltd.) dissolved in 550 parts of toluene was prepared until the dry film thickness was
A charge transfer layer was formed by coating to a thickness of 15 μm, and a laminated photoreceptor No. 1 was prepared. Examples 2 to 28 Photosensitized in the same manner as in Example 1, except that the charge transfer substance used in Example 1 and the bisazo compound shown in Table 2 (synthesized according to Production Examples 1 to 3) were used. Body Nos. 2 to 28 were obtained. These photoconductors No. 1 to 28 were first charged with -6.5KV corona discharge in a dark place using an electrostatic copying paper tester (model SP-428 manufactured by Kawaguchi Electric Manufacturing Co., Ltd.), and then charged with white light at an illuminance of 5lux. The exposure amount E1/2 (lux.sec) for attenuating the surface potential to half of the initial surface potential was determined. The results are shown in Table-2.

【table】

[Table] Also, regarding photoreceptor No. 1, its surface potential is -
After corona discharge to 500V, we repeated a cycle of exposing to white light at 400lux for 2 seconds to examine the change in sensitivity.We found that the initial sensitivity was E1/2 with white exposure at 5lux. is 1.5lux.
sec, E1/5 is 3.1lux.sec (However, E1/2 has the same meaning as above, and E1/5 indicates the amount of exposure necessary for the surface potential to attenuate to one-fifth.) Yes, 2000
The sensitivity after repeating times is E1/2 is 1.4lux.sec, E1/
5 was 3.0lux.sec. When this photoreceptor was set in a copying machine (SF-750 manufactured by Sharp Co., Ltd.) and repeatedly charged and exposed, the change in surface potential between the initial stage and after 2000 cycles was 3%. As shown in the above results, there was very little variation in the electrical properties of this photoreceptor due to repeated use. Furthermore, when a test chart (manufactured by Dataquest Co., Ltd.) was copied, clear images with no fogging were obtained. Example 29 After pulverizing 0.3 part of the same bisazo compound used in Example-1, cyclohexanone 20
and dispersed with an ultrasonic disperser. To this, 30 parts of tetrahydrofuran, polyester (manufactured by Toyobo Co., Ltd.,
Trademark Byron 200) 10 parts and 1,3-diphenyl-
10 parts of 5-(p-dimethylaminophenyl)-2-pyrazoline was added and dissolved. Apply this coating liquid to the thickness
A photosensitive layer having a dry film thickness of 10 μm was provided by coating with a film applicator on an aluminum vapor-deposited layer deposited on a 100 μm polyester film. When the sensitivity of this photoreceptor was measured, E1/2 was 11lux.sec when charged by +6KV corona discharge, and -
18lux.sec for charging by 6KV corona discharge
It was hot.

Claims (1)

[Scope of Claims] 1. A photoreceptor for electrophotography, comprising a photosensitive layer containing an azo compound represented by the following general formula () on a conductive support. (In the above general formula (), Cp represents a coupler residue selected from the following). (In the formula, X is fused with benzene ring A, and together with benzene ring A, a naphthalene ring, an anthracene ring,
Represents an organic group forming a carbazole ring, benzocarbazole ring or dibenzofuran ring, and R ¹
represents a hydrogen atom, an alkyl group, or a phenyl group, and ^R2 represents an alkyl group, a phenyl group, a naphthyl group, or a dibenzofuranyl group, and each of these represents an alkyl group, an alkoxy group, a halogen atom, a nitro group, an amino may be substituted with one or more substituents selected from groups and cyano groups. ) (In the formula, R ³ represents an alkyl group, a benzyl group, or a phenyl group, and any of these may be substituted with one or more substituents selected from an alkoxy group, a halogen atom, or a hydroxy group.) (In the formula, Z represents a divalent group of an aromatic hydrocarbon or a divalent group of a heterocycle containing a nitrogen atom in the ring, and each of these represents an alkyl group, a halogen atom, a nitro group, an amino group, a dialkylamino group) and hydroxy group.)