JPH0579983B2 - - Google Patents

Description

[Detailed description of the invention]

(A) Industrial Application Field The present invention relates to an electrophotographic photoreceptor, and in detail,
The present invention relates to a novel electrophotographic photoreceptor having a photosensitive layer containing an azo pigment. More specifically, the present invention relates to a highly durable electrophotographic photoreceptor that has high sensitivity and is suitable for repeated use. (B) Prior Art and its Problems Conventionally, electrophotographic photoreceptors having a photosensitive layer mainly composed of an inorganic photoconductor such as selenium, zinc oxide, or cadmium sulfide have been widely known. However, these are not necessarily satisfactory in terms of sensitivity, thermal stability, moisture resistance, durability, etc. In particular, selenium and cadmium sulfide are
Due to its toxicity, there were restrictions on manufacturing and handling. On the other hand, an electrophotographic photoreceptor having a photosensitive layer containing an organic photoconductive compound as a main component must be relatively easy to manufacture. Additionally, compared to selenium photoreceptors,
It has many advantages such as excellent thermal stability, and has attracted a lot of attention in recent years. Poly-N-vinylcarbazole is well known as such an organic photoconductive compound, and a charge transfer complex formed from poly-N-vinylcarbazole and a Lewis acid such as 2,4,7-trinitro-9-fluorenone An electrophotographic photoreceptor having a photosensitive layer containing as a main component is not necessarily satisfactory in terms of sensitivity and durability. On the other hand, a laminated or dispersed functionally separated photoreceptor in which the carrier generation function and the carrier movement function are assigned to separate substances, respectively,
There is a wide selection range of each material, charging characteristics, sensitivity,
It has the advantage that an electrophotographic photoreceptor having arbitrary electrophotographic properties such as durability can be produced relatively easily. Conventionally, various carrier-generating substances or carrier-transfer substances have been proposed. For example, an electrophotographic photoreceptor has been put into practical use that has a photosensitive layer that combines a carrier generation layer made of amorphous selenium and a carrier transfer layer mainly composed of poly-N-vinylcarbazole. However, the carrier generating layer made of amorphous selenium has the disadvantage of poor durability. In addition, various proposals have been made to use organic dyes and pigments as carrier generating substances.
JP-A-52-4241, JP-A-54-46558,
Japanese Patent Publication No. 56-11945 and the like are already known. However, these azo pigments are not necessarily satisfactory in terms of characteristics such as sensitivity, residual potential, and stability when used repeatedly, and the selection range of carrier generating substances is also limited, making it difficult for electrophotographic processes. The reality is that nothing that fully satisfies a wide range of demands has yet been obtained. (C) Object of the Invention An object of the invention is to provide an electrophotographic photoreceptor containing an azo pigment that is stable against heat and light and has excellent carrier-generating ability. Another object of the present invention is to provide an electrophotographic photoreceptor with high sensitivity, low residual potential, and excellent durability whose characteristics do not change even after repeated use. Still another object of the present invention is to provide an electrophotographic photoreceptor containing an azo pigment that can effectively act as a carrier generating material even in combination with a wide variety of carrier transfer materials. (D) Structure of the Invention As a result of intensive research to achieve the above object, the present inventor discovered that an azo pigment represented by the following general formula [] can function as an active ingredient of a photoreceptor, and completed the present invention. This is what I did.

[Formula A is hydrogen, an alkyl group which may contain a substituent, a phenyl group which may contain a substituent, a heterocyclic group which may contain a substituent, and n is 0 or 1
, X is hydrogen, a methyl group, a cyano group, or a halogen, and Cp is a coupler residue. ) Cp represents a coupler residue that reacts with a diazo group, and a coupler residue having a structure represented by the following general formula [] is particularly effective.

【formula】

【formula】

【formula】

【formula】

【formula】

【formula】

【formula】

【formula】

[ka]

[Formula] (In the formula, Y is fused with a benzene ring to form naphthalene,
Indicates the atomic group necessary to form a polycyclic aromatic ring such as an anthracene ring or a heterocyclic ring such as a carbazole ring, benzocarbazole ring, or dibendifuran ring by condensation with a benzene ring. R ₁ is an optionally substituted alkyl group (e.g., methyl group, ethyl group, n-propyl group, iso-propyl group, n-butyl group, sec-butyl group, amyl group, 1-octyl group, benzyl group, p-chlorobenzyl group, 3,
4 dichlorobenzyl group, p-methylbenzyl group,
2-phenylethyl group, α-naphthylmethyl group,
β-naphthylmethyl group) aryl group (e.g. phenyl group, tolyl group, xylyl group, biphenyl group,
Chlorophenyl group, dichlorophenyl group, bromphenyl group, methoxyphenyl group, ethoxyphenyl group, butoxyphenyl group, phenoxyphenyl group, nitrophenyl group, cyanophenyl group, hydroxyphenyl group, carboxyphenyl group,
N,N-dimethylaminophenyl group, α, α,
α,-trifluoromethylphenyl group, methylthiophenyl group, α-naphthyl group, β-naphthyl group, etc.) R ₂ is R ₁ and a heterocyclic group (e.g. thiazolyl group,
5-nitrothiazolyl group, carbazolyl group, indolyl group, pyrrolyl group, acridyl group, benzo(b)
thiophenyl, benzimidazolyl group, oxazolyl group, chloroxazolyl group, triazolyl group, piperidyl group, pyridyl group, kyrinol group). R ₃ represents O, S, -NH-, R ₄ and R ₅ are hydrogen, an optionally substituted alkyl group, a nitro group, a methoxy group, an ethoxy group, an acetyl group, a cyano group,
Indicates halogen. Z is a chain hydrocarbon necessary to form a 5-membered ring or a 6-membered ring. ] That is, in the present invention, by using the azo pigment represented by the above general formula [] as a photoconductive substance constituting the photosensitive layer of an electrophotographic photoreceptor, the azo pigment of the present invention has excellent carrier generation. By using this as a carrier generating material for a so-called function-separated type electrophotographic photoreceptor, in which carrier generation and transport are performed using separate substances, the film has excellent physical properties, and has excellent charge retention, sensitivity, and residual properties. An electrophotographic photoreceptor that has excellent electrophotographic properties such as electric potential, has little fatigue deterioration even when used repeatedly, and does not change the above-mentioned properties even when exposed to heat or light, and can exhibit stable properties. can be created. Specific examples of the azo pigment useful in the present invention represented by the above general formula include those having the following structural formula, but the azo pigment of the present invention is not limited thereto. Exemplary azo pigments

[ka]

【table】

【table】

【table】

【table】

【table】

【table】

【table】

【table】

【table】

【table】

【table】

【table】

[Table] Azo pigments represented by the above general formula [] have the general formula

The divalent amino compound represented by the formula is azotized by a conventional method, and then the corresponding coupler is coupled in the presence of an alkali, or the diazonium salt of the divalent amino compound described above is converted into a borofluoride salt or Once isolated in the form of zinc chloride double salt, etc., it can be isolated using a suitable solvent (e.g. N,N-dimethylformamide, dimethylsulfoxide, ethanol, dioxane).
Among them, it can be easily synthesized by carrying out a coupling reaction with a coupler in the presence of an organic or inorganic alkali. Next, a method for synthesizing a representative example of the azo pigment used in the present invention will be described. Synthesis Example (Exemplary Azo Pigment No.-13) Acetophenone and p-nitrohydrazine are reacted in equal moles in ethanol to form acetophenone-
(P-nitrophenyl hydrazone is obtained. The hydrazone thus obtained is used with phosphorus oxychloride and dimethylformamide to obtain a pyrazole compound represented by the following structural formula.

[Chemical formula] The aldehyde form of pyrazole obtained in this way and p-nitrobenzyl cyanide were dissolved in dioxane, and piperidine was allowed to act on the solution.
(p-nitrophenyl)-3-phenyl-4-(β
-cyano-p-nitrostyryl)-pyrazole is obtained. Recrystallization was performed using pyridine. The dinitro compound thus obtained was reduced with iron powder and glacial acetic acid to easily obtain a diamino compound having the following structural formula.

[Formula] According to IR (KBr tablet method), the absorption caused by the nitro group at 1340 cm ^-1 disappeared, and in its place a new absorption caused by the amino group appeared at 3320 cm ^-1 . In addition, absorption due to cyano groups was observed at 2200 cm ^-1 . 0.75 g of the diamino compound thus obtained was added to 2N-
After dissolving in 20 ml of hydrochloric acid and removing insoluble matter, a solution of 0.5 g of sodium nitrite dissolved in the minimum amount of water was added dropwise under ice cooling, and the mixture was allowed to react for about 1 hour. Activated carbon was then added and filtered to prepare a diazonium solution. As coupling components, 1.2 g of 2-hydroxy-N-(4-cyanophenyl)-3-naphthoic acid amide having the following structure and 1.0 g of triethylamine were dissolved in 20 ml of dimethyl sulfoxide and cooled to 0 to 5°C. Next, the above diazonium salt was added dropwise into the coupler solution, and the resulting black-purple paste liquid was
The temperature was maintained at 10°C and stirring was continued for an additional 3 hours. The generated precipitate was filtered, thoroughly washed with dimethylformamide, then with hot water, and finally with acetone. After drying at 80°C for about 5 hours, 1.05 g of a black powder with a slightly metallic luster was obtained. . The decomposition point was around 345°C. Other azo pigments of the present invention can also be obtained according to the above synthesis example. The electrophotographic photoreceptor of the present invention has the general formula []
It has a photosensitive layer containing one or more azo pigments represented by: Various forms of photosensitive layers are well known, and the photosensitive layer of the electrophotographic photoreceptor of the present invention may be in any of them. The photosensitive layer is usually of the type exemplified below. A photosensitive layer made of an azo pigment A photosensitive layer containing an azo pigment dispersed in a binder A photosensitive layer containing an azo pigment dispersed in a well-known charge transfer substance Photosensitive layer laminated with a charge transfer layer containing a photosensitive layer The azo pigment represented by the above general formula generates charge carriers with extremely high efficiency when it absorbs light. Although the generated carrier can be transferred using an azo pigment as a medium, it is preferable to use a known charge transfer material as a medium. From this point of view, photosensitive layers in the form of and are particularly preferred. Charge transfer substances are generally classified into two types: electron transfer substances and hole transfer substances, and both can be used in the photosensitive layer of the photoreceptor of the present invention.
Mixtures of substances having the same type of function or mixtures of substances having different types of functions can also be used. Substances with electron transfer include nitro group, cyano group,
It is an electron-withdrawing compound having an electron-withdrawing group such as an ester group, and examples of these include 2,
4,7-trinitrofluorenone, 2,4,5,
Nitrated fluorenone such as 7-tetranitrofluorenone, or tetracyanoquinodimethane,
Compounds such as tetracyanoethylene, 2,4,5,7-tetranitroxanthone, 2,4,8-trinitrothioxanthone, and polymerized products of these electron-absorbing compounds are included. Furthermore, examples of electron-donating organic photoconductive compounds that can be used as hole transport media include the following. hydrazones

【formula】

【formula】

【formula】

[ka]

【formula】

【formula】

[ka]

【formula】

【formula】

【formula】

【formula】

[ka]

[ka]

[ka]

【formula】

【formula】

[ka]

【formula】

[ka]

[ka]

[ka]

[ka]

[ka] Pyrazolines

[ka]

[ka]

[ka]

[ka]

[ka]

[ka]

【formula】

[ka]

[ka] diaryl alkanes

[ka]

[ka]

[ka]

[ka]

[ka]

[ka]

[ka]

[ka]

[ka]

[ka]

[ka]

[ka] Alkylene diamines

【formula】

【formula】

[ka]

【formula】

[ka] Dibenzylanilines

【formula】

【formula】

【formula】

【formula】

[ka]

[ka]

[ka]

[ka]

[ka]

[ka] Triphenylamines

【formula】

【formula】

【formula】

【formula】 dienylbenzylamines

【formula】

[ka] Triaryl alkanes

[ka]

[ka]

[ka]

[ka]

[ka]

[ka]

[ka]

[ka] Oxadiazoles

[ka]

[ka]

[ka]

[ka]

[ka]

【formula】 anthracenes

[ka]

[ka] Oxazoles and oxathiazoles

【formula】

[ka]

【formula】

[ka]

[ka]

[C] etc. can be mentioned. Other polymeric compounds that can be used include poly-N-vinylcarbazole, halogenated poly-N-vinylcarbazole, polyvinylpyrene, polyvinylanthracene, polyvinylacridine, polyglycidylcarbazole, polyvinylacenaphthylene, and ethylcarbazole formaldehyde resin. can. The carrier transfer substances are not limited to those described herein, and when used, one type or a mixture of two or more types of carrier transfer substances can be used. The electrophotographic photoreceptor of the present invention can be manufactured according to a conventional method. For example, an electrophotographic photoreceptor having the above-mentioned type of photosensitive layer can be prepared by coating a coating solution obtained by dissolving or dispersing an azo pigment represented by the above general formula [] in a suitable medium on a conductive support; dry,
It can be manufactured by forming a photosensitive layer with a thickness of usually several 0.1 μm to several tens of μm. As a medium for preparing the coating solution, a basic solvent that dissolves an azo pigment such as n-butylamine or ethylenediamine, or tetrahydrofuran, 1,4
- Ethers such as dioxane: Ketones such as methyl ethyl ketone and cyclohexanone: toluene,
Aromatic hydrocarbons such as xylene: Aprotic polar solvents such as N,N-dimethylformamide, acetonitrile, N-methylpyrrolidone, dimethyl sulfoxide: Alcohols such as methanol, ethanol, isopropanol: ethyl acetate, methyl acetate, methyl cellosolve Esters such as acetate: Media for dispersing azo pigments such as chlorinated hydrocarbons such as dichloroethane and chloroform can be mentioned. When using a medium for dispersing azo pigments,
The azo pigment has a particle size of 5 μm or less, preferably 3 μm or less,
Optimally, it is necessary to make the particles smaller than 1 μm. Furthermore, as the conductive support on which the photosensitive layer is formed, any of those employed in well-known electrophotographic photoreceptors can be used. Specifically, 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, 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. Also included are plastic sheets and drums that contain conductive substances such as metal powder, carbon black, and carbon fibers and are rendered conductive. An electrophotographic photoreceptor having the above type of photosensitive layer can be produced by dissolving a binder in a coating liquid used for forming the above type of photosensitive layer. In this case, the medium of the coating liquid is preferably one that dissolves the binder. As a binder, styrene, vinyl acetate,
Polymers and copolymers of vinyl compounds such as acrylic esters and methacrylic esters, phenoxy resins, polysulfones, arylate resins, polycarbonates, polyesters, cellulose esters, cellulose ethers, butyral resins, epoxy resins, acrylic polyol resins, etc. Examples include polymers. The amount of binder used is usually based on the azo pigment.
It is in the range of 0.1 to 5 times the weight. In forming this type of photosensitive layer, it is preferable that the azo pigment be present in the binder in the form of fine particles, for example, with a particle size of 3 μm or less, particularly 1 μm or less. Similarly, an electrophotographic photoreceptor having the above-mentioned type of photosensitive layer can be manufactured by dissolving a charge transfer medium in the coating liquid used to form the above-mentioned type of photosensitive layer. As the charge transfer medium, any of those exemplified above can be used. Apart from charge transport media which can themselves be used as binders, such as polyvinylcarbazole and polyglycidylcarbazole, it is preferred to use other binders. As the binder, any of those exemplified above can be used. In this case, the amount of the binder used is usually in the range of 0.5 to 100 times the weight of the azo pigment, and the amount of the charge medium used is usually in the range of 0.2 to 3.0 times, preferably 0.3 to 1.2 times the weight of the binder. be. In the case of a charge transport medium which itself can be used as a binder, it is usually used 1 to 10 times the weight of the azo pigment. In this type of photosensitive layer, as in the above-mentioned type of photosensitive layer, it is preferable that the azo pigment is present in the charge transport medium and the binder in the form of fine particles. If a coating solution obtained by dissolving a charge transfer medium in a suitable medium is applied onto the photosensitive layer of the type of ~ above and dried to form a charge transfer layer, an electrophotographic photosensitive layer having the photosensitive layer of the type described above can be obtained. body can be manufactured. In this case, the photosensitive layer of the type ~ plays the role of a charge generation layer. The charge transfer layer does not necessarily need to be provided above the charge generation layer, but may be provided between the charge generation layer and the conductive support. However, the former is preferable in terms of durability. The charge transfer layer is formed in the same manner as the photosensitive layer described above. That is, the coating liquid for forming the photosensitive layer described above except the azo pigment may be used as the coating liquid. Typically the charge transport layer is 5-50 μm thick. 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
- quinones such as chlor-5-nitroanthraquinone, 2-chloroanthraquinone, and phenathrenequinone, aldehydes such as 4-nitrobenzaldehyde, 9-benzoylanthracene, indanedione, 3,5-dinitrobenzophenone,
Ketones such as 3,3',5,5-tetranitrobenzophenone, acid anhydrides such as phthalic anhydride and 4-chloronaphthalic anhydride, tetracyanoethylene,
Cyano compounds such as terephthalmalondinitrile and 4-nitrobenzalmalonnitrile; 3-benzalphthalide, 3-(α-cyano-p-nitrobenzal)phthalide, 3-(α-cyano-p-chlorobenzal)phthalides, etc. Examples include electron-withdrawing compounds. 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. In addition, inorganic photoconductive fine particles such as selenium and selenium-arsenic alloys, and organic photoconductive pigments such as copper-phthalocyanine pigments and perylene pigments may also be contained. 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 aromatic compounds such as phthalate esters, phosphate esters, epoxy compounds, chlorinated paraffins, chlorinated fatty acid esters, and alkylated naphthalenes. It goes without saying that the film may also include an adhesive layer, an intermediate layer, an insulating photoreceptor, and a protective layer, if necessary. The photoreceptor using the azo pigment of the present invention has high sensitivity and good color sensitivity, and when used repeatedly,
Less fluctuation in sensitivity and chargeability, less photo fatigue,
It is also extremely durable. Furthermore, the photoreceptor of the present invention can be widely used in electrophotographic applications such as photoreceptors for printers using lasers, cathode ray tubes (CRTs), and light emitting diodes (LEDs) as light sources, in addition to electrophotographic copying machines. (E) Examples Next, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to the following Examples unless the gist thereof is exceeded. Example 1 Vinyl chloride:vinyl acetate:maleic anhydride copolymer (Eslec MF-, manufactured by Sekisui Chemical Co., Ltd.) was coated on a conductive support consisting of a polyester film laminated with aluminum foil (Albetz 85 manufactured by Daido Kako Co., Ltd., aluminum film thickness 10μ). 10) to form an intermediate layer with a thickness of 0.05 μm consisting of 2 g of Exemplary Azo Pigment-12 and butyral resin (Eslex B manufactured by Sekisui Chemical Co., Ltd.).
An azo pigment dispersion obtained by adding 1g of pigment to 100ml of tetrahydrofuran and dispersing it in a bait conditioner for about 1 hour was applied onto the intermediate layer and dried so that the film thickness after drying was 0.3μ. A carrier generating layer is formed, and a carrier transfer substance N,N-dibenzylaminobenzaldehyde is formed.
5 g of 1,1-diphenylhydrazone and 7 g of polyarylate resin were added together with 50 g of 1,2-dichloroethane.
An electrophotographic photoreceptor of the present invention was prepared by coating and drying a solution dissolved in 1 ml of the solution to a dry film thickness of 19 μm to form a carrier transfer layer. After storing this photoreceptor at room temperature at 30℃ in a dark place for one week, this electrophotographic photoreceptor was attached to an electrostatic paper tester "SP-428" (manufactured by Kawaguchi Electric Seisakusho) and the following characteristic tests were performed. Ta. That is, a voltage of -6KV is applied to the charger to charge the photosensitive layer by corona discharge for 5 seconds, and the potential Vo (-V) at that time and the illuminance on the surface of the photosensitive layer are then
The exposure amount E1/2 (lux·sec) required to attenuate the surface potential of the photosensitive layer to 1/2 by irradiating it with light from a halogen lamp under a condition of 30 lux was determined. Further, the surface potential after exposure with an exposure amount of 50 lux·sec, that is, the residual potential E ₅₀ (−V) was determined. Similar measurements were repeated 500 times. Incidentally, the residual potential was further reduced to zero by further exposure for 0.3 seconds at 300 lux using a tungsten lamp as a light source to reduce the residual potential. The results are shown in Table 1.

[Table] Examples 2 to 6 A total of five types of the present invention were prepared in the same manner as in Example 1, except that exemplified azo pigments -1, -28, -35, -12, and -3 were used as carrier generating substances, respectively. Electrophotographic photoreceptors were prepared and similar characteristic tests were conducted on each of them. The results are shown in Table 2.

[Table] Example 7 An intermediate layer of diallyl phthalate resin (Daiso Tap B Osaka Soda) with a thickness of 0.1 μm was formed on the outer surface of a drum made of aluminum with a diameter of 60 mm, and 2 g of Exemplary Azo Pigment-23 was added to the outer surface of a drum made of aluminum with a diameter of 60 mm. 100ml of tetrahydrofuran with 2g of arylate resin dissolved in it
Approximately 3 times using a vent conditioner in addition to
A dispersion obtained by time-dispersing was applied and dried on the intermediate layer so that the film thickness after drying was 0.5 μm to form a carrier generation layer. On this carrier generation layer, the structural formula

10 g of the carrier transfer substance N,N-diethylaminobenzaldehyde-1-(phenyl)-1-methylhydrazone represented by the formula is mixed with 12 g of polycarbonate resin (Teijin Panlite L-1250) and 1,2 dichloroethane.
A solution dissolved in 100 ml was applied and dried to a film thickness of 15 μm after drying to form a carrier transfer layer, thereby producing a drum-type electrophotographic photoreceptor according to the present invention. When this electrophotographic photoreceptor was installed in our modified commercially available cartridge-type electronic copying machine and a copied image was formed, a clear visible image with high contrast and faithfulness to the original was obtained. Also, although I repeated copying 1000 times, the first
A visible image equivalent to the second time was obtained. Example 8 The reflection spectrum of the drum-type electrophotographic photoreceptor obtained in Example 7 was measured using a spectrophotometer equipped with an integrating sphere (Shimadzu UV-365), and the maximum absorption wavelength in the visible region of this photoreceptor was determined. was found to be around 650nm to 690nm. Furthermore, the spectral sensitivity of this photoreceptor between 500 nm and 750 nm was measured using a monochromator, and the results are shown in FIG. It was found that the photoreceptor has sufficient practical sensitivity even when a light emitting diode or a He-Ne laser is used as a light source. Example 9 Styrene:n on a grained surface oxidized Al plate
-Butyl methacrylate: methacrylic acid copolymer (styrene: n-butyl methacrylate = 1:2
Weight ratio, oxidation 250) and exemplary azo pigments-35 and 2
-Phenyl-1-ethylindole-3-aldehyde 1,1-diphenylhydrazone 1.5:0.2:
Blend at a weight ratio of 1.1, and add this in dioxane.
A solution containing dissolved (resin component, hydrazone compound) and dispersed (azo pigment) was applied and dried, and an electrophotographic property test was conducted using the electrostatic paper tester described above on a single layer type photoreceptor having a film thickness of 6 μm. Applied voltage +6KV Vo=520Volt E1/2=4.1lux・sec. In addition, this photoreceptor is visualized with a developer (toner), and then an alkaline processing aqueous solution (for example, 3% triethanolamine, 10% ammonium carbonate, 15%
When treated with polyethylene glycol (% average molecular weight 190-210, 5% benzyl alcohol), the toner-free areas are easily eluted, and then washed with water containing sodium silicate to easily create a printing original plate. I was able to do that. When offset printing is performed using this original plate, approximately
It was found that it could withstand printing of 100,000 sheets. In addition, the optimum exposure amount (light source: halogen lamp) was 150 lux·sec to obtain a visible toner image, and the printing original plate was prepared by direct plate making without using any plate material.

[Brief explanation of the drawing]

FIG. 1 is a spectral curve of the photoreceptor of the present invention in Example 8.

Claims (1)

[Scope of Claims] 1. An electrophotographic photoreceptor comprising a photosensitive layer containing an azo pigment represented by the following general formula [] on a conductive support. [Formula A is hydrogen, an alkyl group that may contain a substituent, a phenyl group that may contain a substituent, a heterocyclic group that may contain a substituent, n is 0 or 1, and X is (Hydrogen, methyl group, cyano group, halogen, and Cp is a coupler residue.) 2. The photosensitive layer contains a carrier transfer substance and a carrier generation substance, and the carrier generation substance is represented by the general formula []. The electrophotographic photoreceptor according to claim 1, which is an azo pigment shown in the following. 3. The electrophotographic photoreceptor according to claim 1, wherein the azo pigment represented by the general formula [] is a compound represented by the following structural formula. [C] (In the formula, A, n, X, and Cp have the same meanings as the first term.)