JPH042946B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to an electrophotographic photoreceptor, and particularly to an electrophotographic photoreceptor in which a photosensitive layer contains a specific azo pigment. [Prior Art] Electrophotographic photoreceptors using inorganic photoconductors such as selenium, cadmium sulfide, and zinc oxide as photosensitive components have been known. On the other hand, since it was discovered that certain organic compounds exhibit photoconductivity, many organic photoconductors have been developed. For example, organic photoconductive polymers such as poly-N-vinylcarbazole and polyvinylanthracene, carbazole, anthracene, pyrazolines, oxadiazoles, hydrazones,
Organic pigments and dyes such as low-molecular organic photoconductors such as polyarylalkanes, phthalocyanine pigments, azo pigments, cyanine dyes, polycyclic quinone pigments, berylene pigments, indigo dyes, thioindigo dyes, or methine squaritate dyes are used. Are known. In particular, organic pigments and dyes with photoconductivity are
Many photoconductive organic pigments and dyes have been proposed because they are easier to synthesize than inorganic materials, and the variety of compounds that exhibit photoconductivity in an appropriate wavelength range has expanded. For example, US Patent No. 4123270, US Patent No. 4247614, US Patent No.
No. 4251613, No. 4251614, No. 4256821, No. 4260672, No. 4268596, No. 4278747,
As disclosed in No. 4,293,628, electrophotographic photoreceptors are known in which a disazo pigment exhibiting photoconductivity is used as a charge-generating substance in a photosensitive layer that is functionally separated into a charge-generating layer and a charge-transporting layer. An electrophotographic photoreceptor using such an organic photoconductor can be produced by a coating method by appropriately selecting a binder, so it has extremely high productivity.
Although this photoreceptor has the advantage of being able to provide an inexpensive photoreceptor and the sensitivity wavelength range can be freely controlled by selecting organic pigments, this photoreceptor has poor sensitivity and durability, so it has not been put into practical use until now. There are very few things. [Problems to be Solved by the Invention] An object of the present invention is to provide a novel electrophotographic photoreceptor. Another object of the present invention is to provide an electrophotographic photoreceptor having practically excellent sensitivity and durability. [Means for solving the problem] That is, the present invention solves the following general formula (1) (In the formula, Ar ₁ , Ar ₂ and Ar ₃ each represent an arylene group or a divalent heterocyclic group which may have a substituent, and at least one of Ar ₁ , Ar ₂ and Ar ₃ is naphthylene, biphenylene, (A is a group selected from the group consisting of anthricane and a divalent heterocyclic group, and A represents a coupler residue having a phenolic OH group.) The photosensitive layer is characterized by containing a trisazo pigment represented by It is an electrophotographic photoreceptor. In the general formula (1), Ar ₁ , Ar ₂ and Ar ₃ are defined as arylene groups such as phenylene, biphenylene, naphthylene, and anthrylene. In addition, examples of substituents that may be substituted with these include hydroxy group, halogen (chloro, bromo, iodo, etc.), alkyl (methyl, ethyl,
propyl, butyl, etc.), alkoxy (methoxy,
(ethoxy, propoxy, butoxy, etc.), aryloxy groups (phenyloxy, etc.), substituted amino (dimethylamino, diethylamino, dibenzylamino, pyrrolidino, piperidino, morpholino, etc.), nitro, cyano, acyl (acetyl, benzoyl, etc.), etc. be done. Furthermore, as definitions of Ar ₁ , Ar ₂ , and Ar ₃ , heterocyclic groups include, for example, benzoxazole, benzothiazole,
These are divalent groups such as pyridine, quinoline, thiophene, and carbazole, and these may be substituted with the above-mentioned substituents. At least one of Ar ₁ , Ar ₂ and Ar ₃ is an arylene group selected from the group consisting of biphenylene, naphthylene and anthrylene which may have a substituent. Furthermore, the phenolic nature of A in general formula (1)
Examples of coupler residues having an OH group include the following general formulas (2) to (8): (In the formula, X is a residue that is fused with a benzene ring to form a polycyclic aromatic ring or a heterocycle; R ₃ and R ₄ are hydrogen,
Alkyl, aralkyl, aryl or heterocyclic group which may have a substituent or a group which is bonded to each other to form a cyclic amino group with a nitrogen atom; R ₅ and R ₆ are alkyl which each may have a substituent;
Aralkyl, aryl group; Y is a divalent aromatic hydrocarbon group or a divalent heterocyclic group having a nitrogen atom; R ₇ is an aryl or heterocyclic group that may have a substituent; R ₈ and R ₉ represents an alkyl, aralkyl, aryl or heterocyclic group which each may have a substituent. ) Examples of the polycyclic aromatic ring of X include naphthalene, anthracene, carbazole, benzcarbazole, dibenzofuran, benzonaphthofuran,
Examples include diphenylene sulfide. These may be substituted with the substituents described above. In addition, in the case of R ₃ and R ₄ , alkyl is, for example, methyl,
Ethyl, propyl, butyl, etc. are shown, aralkyl is, for example, benzyl, phenethyl, naphthylmethyl, etc., and aryl is, for example, phenyl, diphenyl, naphthyl, anthryl, etc. Particularly preferred is a compound having a structure in which R ₃ is hydrogen and R ₄ is a phenyl group having an electron-withdrawing group such as halogen, nitro, cyano, or trifluoromethyl at the o-position. These may have substituents. Examples of the heterocycle include carbazole, dibenzofuran, benzimidazolone, benzthiazole, thiazole, and pyridine. Specific examples of R ₅ and R ₆ include the same ones as exemplified above for R ₃ and R ₄ . These may be substituted with the substituents described above. In the definition of Y, examples of divalent aromatic hydrocarbons include monocyclic aromatic hydrocarbon groups such as o-phenylene, o-naphthylene, perinaphthylene, 1,
Examples include fused polycyclic aromatic hydrocarbon groups such as 2-antrylene and 9,10-phenanthrylene.
Further, examples of the heterocyclic divalent group having a nitrogen atom include a 3,4-pyrazolediyl group, a 2,3-pyridinediyl group, a 4,5-pyrimidinediyl group,
Examples include 5- to 6-membered heterocyclic divalent groups such as 6,7-indazolediyl group, 5,6-benzimidazolediyl group, and 6,7-quinolinediyl group. Examples of the aryl group or heterocyclic group for R ₇ include phenyl, naphthyl, anthryl, pyrenyl, and the like; pyridyl, thienyl, furyl, carbazolyl, and the like. These may be substituted with the substituents described above. Specific examples of alkyl, aryl, and aralkyl for R ₈ and R ₉ are the same as those listed above. Examples of the heterocycle include carbazole, dibenzofuran, benzimidazolone, benzthiazole, thiazole, and pyridine. These may be substituted with the substituents described above. Although the present invention is not bound by theory, the structure of the azo pigment of general formula (1)

[Formula] The lone pair of nitrogen atoms in the structure maintains the conjugation between the azo groups of the pigment molecule, allowing the charge generated by light to move freely, allowing for good charge transfer between molecules. Conceivable. Therefore, by incorporating the azo pigment of the general formula (1) into the photosensitive layer, either or both of the carrier generation efficiency and the carrier transport efficiency will be improved, thereby improving the sensitivity and ensuring potential stability during long-term use. That will happen. Furthermore, high sensitivity is achieved, making it possible to apply it to laser beam printers, LED printers, liquid crystal printers, etc. Furthermore, since a stable potential is ensured regardless of the previous history of the photoreceptor, stable and beautiful images can be obtained. Representative examples of azo pigments used in the present invention are listed in Table 1.

【table】

【table】

【table】

【table】

【table】

【table】

【table】

【table】

【table】

【table】

【table】

【table】

【table】

【table】

【table】

【table】

【table】

【table】

【table】

【table】

[Table] These disazo pigments can be used alone or in combination of two or more. Additionally, these pigments may have, for example, the general formula (However, Ar ₁ , Ar ₂ and Ar ₃ in the formula have the same meanings as the symbols in general formula (1).) The triamine represented by the formula (1) is hexazotized by a conventional method, and then the corresponding coupler is converted into an aqueous solution in the presence of an alkali. After coupling or once isolating the hexazonium salt of the above-mentioned triamine in the form of a borofluoride salt or zinc chloride double salt, an alkaline solution is added in a suitable solvent such as N,N-dimethylformamide or dimethyl sulfoxide. It can be easily produced by coupling with a coupler in the presence of a compound. Next, a typical synthesis example of the trisazo pigment used in the present invention is shown below. Synthesis Example (Synthesis of the above-mentioned exemplified trisazo pigment No. 1) In a 500ml beaker, 120ml of water and 24.9ml of concentrated hydrochloric acid (0.29ml) were added.
mol), compound of formula 9.98 (0.029 mol) The mixture was cooled in an ice-water bath and stirred to bring the liquid temperature to 3°C. Next, add 6.4 g (0.093 mol) of sodium nitrite to 11 ml of water.
ml of the solution was added dropwise over 10 minutes while controlling the temperature within the range of 3 to 10°C, and after the dropwise addition was completed, the solution was stirred for an additional 30 minutes at the same temperature. Carbon was added to the reaction solution and filtered. 38.2g of sodium borohydrofluoride in the filtrate
(0.35 mol) dissolved in 65 ml of water was added, and the precipitate precipitated was separated by filtration, washed with water, and thoroughly pressed on a filter to obtain hexazonium trifluoroborate in a wet state. Next, add DMF1800 to 2 beakers.
ml and 24.5 g (0.093 mol) of 3-hydroxy-2-naphthoic acid anilide as a coupling component.
and the above-mentioned hexazonium salt were dissolved and the liquid temperature was cooled to 7°C. While stirring this solution, 61.7 g (0.61 mol) of triethylamine was added dropwise into the solution over 30 minutes while maintaining the liquid temperature at 5 to 10°C. After the dropwise addition was completed, the mixture was stirred for another 2 hours, left at room temperature overnight, and then the reaction solution was filtered. The obtained pigment was stirred with 1 part of water, washed, and filtered 3 times each, and then 4 times with 600 ml of DMF.
Stirring, washing, and filtration were repeated twice with 600 ml of MEK. The resulting paste was dried with air at room temperature.
g (yield: 85%) of pigment was obtained. Melting point 250°C or higher Elemental analysis Calculated value % Actual value % C 75.24 75.01 H 4.33 4.13 N 10.82 10.73 Other trisazo pigments represented by the general formula (1) can also be synthesized by the same method as the above synthesis example. In a preferred embodiment of the present invention, a trisazo pigment represented by the general formula (1) can be used as a charge generation substance in an electrophotographic photoreceptor in which the photosensitive layer is functionally separated into a charge generation layer and a charge transport layer. The charge generation layer contains as much of the trisazo pigment as possible in order to obtain sufficient absorbance, and in order to prevent the generated charge carriers from being trapped within the charge generation layer, a thin film layer, for example less than 5 microns, is used. ,
Preferably, it is a thin film layer having a thickness of 0.01 micron to 1 micron. This means that most of the incident light is absorbed by the charge generation layer, generating many charge carriers, and that the generated charge carriers are transferred to the charge transport layer without being deactivated by recombination or trapping. This is due to the need for injection. The charge generation layer can be formed by dispersing the above-mentioned trisazo pigment in a suitable binder and coating it on the substrate, or can be obtained by forming a deposited film using a vacuum deposition device. can. Binders that can be used to form the charge generating layer by coating can be selected from a wide range of insulating resins, and can also be selected from organic photoconductive polymers such as poly-N-vinylcarbazole, polyvinylanthracene, and polyvinylpyrene. . Preferably, polyvinyl butyral, polyarylate (condensation polymer of bisphenol A and phthalic acid, etc.), polycarbonate (bisphenol A, Z type, etc.) polyester, phenoxy resin, polyvinyl acetate, acrylic resin, polyacrylamide resin,
Polyamide, polyvinylpyridine, cellulose resin, urethane resin, epoxy resin, casein,
Examples include insulating resins such as polyvinyl alcohol and polyvinylpyrrolidone. The resin contained in the charge generation layer is preferably 80% by weight or less.
40% by weight or less is suitable. Solvents that dissolve these resins vary depending on the type of resin, and are preferably selected from those that do not dissolve the charge transport layer or undercoat layer described below. Specific organic solvents include alcohols such as methanol, ethanol, and isopropanol, ketones such as acetone, methyl ethyl ketone, and cyclohexanone, N,N-dimethylformamide,
Amides such as N,N-dimethylacetamide,
Sulfoxides such as dimethyl sulfoxide, ethers such as tetrahydrofuran, dioxane, and ethylene glycol monomethyl ether, esters such as methyl acetate and ethyl acetate, aliphatic halogens such as chloroform, methylene chloride, dichloroethylene, carbon tetrachloride, and trichloroethylene. Hydrocarbons or aromatics such as benzene, toluene, xylene, ligroin, monochlorobenzene, dichlorobenzene, etc. can be used. Coating can be carried out using coating methods such as dip coating, spray coating, spinner coating, bead coating, Meyer bar coating, blade coating, roller coating, and curtain coating. For drying, it is preferable to dry to the touch at room temperature and then heat dry. Heat drying at a temperature of 30℃ to 200℃ for 5 minutes to 2
It can be carried out stationary or under a draft for a time range of hours. The charge transport layer is electrically connected to the charge generation layer described above, and has the function of receiving charge carriers injected from the charge generation layer in the presence of an electric field and transporting these charge carriers to the surface. ing. At this time, this charge transport layer may be laminated on or under the charge generation layer. When a charge transport layer is formed on a charge generation layer, the substance that transports charge carriers in the charge transport layer (hereinafter simply referred to as a charge transport substance) is substantially in the wavelength range of electromagnetic waves to which the charge generation layer is sensitive. Preferably, it is insensitive to. The reason is to prevent the charge transport layer from having a filter effect and reducing sensitivity. The “electromagnetic wave” mentioned here is γ
It includes a broad definition of "light ray" that includes radiation, X-rays, ultraviolet rays, visible light, near infrared rays, infrared rays, far infrared rays, and the like. Charge transport substances include electron transport substances and hole transport substances, and electron transport substances include chloranil, promoanil, tetracyanoethylene, tetracyanoquinodimethane, and 2,4,7-trinitro-9-fluorenone. , 2, 4, 5, 7-
Tetranitro-9-fluorenone, 2,4,7-
trinitro-9-dicyanomethylenefluorenone, 2,4,5,7-tetranitroxanthone,
Examples include electron-withdrawing substances such as 2,4,8-trinitrothioxanthone, and polymerized versions of these electron-withdrawing substances. Examples of hole-transporting substances include pyrene, N-ethylcarbazole, N-isopropylcarbazole,
N-Methyl-N-phenylhydrazino-3-methylidene-9-ethylcarbazole, N,N-diphenylhydrazino-3-methylidene-9-ethylcarbazole, N,N-diphenylhydrazino-
3-methylidene-10-ethylphenothiazine,
N,N-diphenylhydrazino-3-methylidene-10-ethylphenoxazine, P-diethylaminobenzaldehyde-N,N-diphenylhydrazone, P-diethylaminobenzaldehyde-N
-α-naphthyl-N-phenylhydrazone, P-
Pyrrolidinobenzaldehyde-N,N-diphenylhydrazone, 1,3,3-trimethylindolenine-ω-aldehyde-N,N-diphenylhydrazone, P-diethylbenzaldehyde-3-methylbenzthiazolinone-2-hydrazone hydrazones such as 2,5-bis(P-diethylaminophenyl)-1,3,4-oxadiazole, 1
-Phenyl-3-(P-diethylaminostyryl)
-5-(P-diethylaminophenyl)pyrazoline, 1-[quinolyl(2)]-3-(P-diethylaminostyryl)-5-(P-diethylaminophenyl)pyrazoline, 1-[pyridyl(2)]- 3-(P-
diethylaminostyryl]-5-(P-diethylaminophenyl)pyrazoline, 1-[6-methoxy-pyridyl(2)]-3-(P-diethylaminostyryl)-5-(P-diethylaminophenyl)pyrazoline, 1- [pyridyl(3)]-3-(P-diethylaminostyryl)-5-(P-diethylaminophenyl)pyrazoline, 1-[pyridyl(2)]-3-(P-
diethylaminostyryl)-5-(P-diethylaminophenyl)pyrazoline, 1-[pyridyl(2)]-
3-(P-diethylaminostyryl)-4-methyl-5-(P-diethylaminophenyl)pyrazoline, 1-[pyridyl(2)]-3-(α-methyl-P-
diethylaminostyryl)-5-(P-diethylaminophenyl)pyrazoline, 1-phenyl-3-
(P-diethylaminostyryl)-4-methyl-5
-(P-diethylaminophenyl)pyrazoline,
1-Phenyl-3-(α-benzyl-P-diethylaminostyryl)-5-(P-diethylaminophenyl)pyrazoline, spiropyrazoline and other pyrazolines, 2-(P-diethylaminostyryl)
-6-diethylaminobenzoxazole, 2-
Oxazole compounds such as (P-diethylaminophenyl)-4-(P-dimethylaminophenyl)-5-(2-chlorophenyl)oxazole, 2
Thiazole compounds such as -(P-diethylaminostyryl)-6-diethylaminobenzothiazole, triarylmethane compounds such as bis(4-diethylamino-2-methylphenyl)-phenylmethane, 1,1-bis(4-N,N -diethylamino2-methylphenyl)heptane, 1,1,
Polyarylalkanes such as 2,2-tetrakis(4-N,N-dimethylamino-2-methylphenyl)ethane, triphenylamine, stilbene derivatives, aromatic polycyclic compounds having a styryl group,
Examples include heterocyclic compounds, poly-N-vinylcarbazole, polyvinylpyrene, polyvinylanthracene, polyvinylacridine, poly-9-vinylphenylanthracene, pyrene-formaldehyde resin, ethylcarbazole formaldehyde resin, and the like. In addition to these organic charge transport materials, inorganic materials such as selenium, selenium-tellurium amorphous silicon, and cadmium sulfide can also be used. Moreover, these charge transport substances may be one or two types.
More than one species can be used in combination. When the charge transport material does not have film-forming properties,
A film can be formed by selecting an appropriate binder. Resins that can be used as binders are:
For example, insulation properties of acrylic resin polyarylate, polyester, polycarbonate (bisphenol A, Z type, etc.) polystyrene, acrylonitrile-styrene copolymer, acrylonitrile-butadiene copolymer, polyvinyl butyral, polyvinyl formal, polysulfone, polyacrylamide, polyamide, chlorinated rubber, etc. resin,
Alternatively, organic photoconductive polymers such as poly-N-vinylcarbazole, polyvinylanthracene, and polyvinylpyrene can be mentioned. Since the charge transport layer has a limit in its ability to transport charge carriers, it cannot be made thicker than necessary. Typically it is between 5 microns and 30 microns, with a preferred range between 8 microns and 20 microns. When forming the charge transport layer by coating, an appropriate coating method as described above can be used. A photosensitive layer having such a laminated structure of a charge generation layer and a charge transport layer is provided on a substrate having a conductive layer. As the substrate having a conductive layer, materials that are themselves conductive can be used, such as aluminum, aluminum alloy, copper, zinc, stainless steel, vanadium, molybdenum, chromium, titanium, nickel, indium, gold, and platinum. In addition, plastics (e.g., polyethylene, polypropylene, polyvinyl chloride, polyethylene terephthalate, acrylic resin, polyethylene fluoride, etc.) or conductive particles (e.g. carbon black, silver particles, etc.) coated on plastic together with a suitable binder, substrates in which conductive particles are impregnated into plastic or paper, and conductive polymers. It is possible to use plastics having the following properties. A subbing layer having barrier and adhesive functions can also be provided between the conductive layer and the photosensitive layer. The undercoat layer is made of casein, polyvinyl alcohol, nitrocellulose, ethylene-acrylic acid copolymer, polyamide (nylon 6, nylon 66, nylon
610, copolymerized nylon, alkoxymethylated nylon, etc.), polyurethane, gelatin, aluminum oxide, etc. The thickness of the undercoat layer is 0.1 micron to 5 micron.
Preferably, 0.5 micron to 3 micron is appropriate. When using a photoreceptor in which a conductive layer, a charge generation layer, and a charge transport layer are laminated in this order, and the charge transport material is an electron transport material, the surface of the charge transport layer must be positively charged, and exposure after charging is required. Then, in the exposed area, electrons generated in the charge generation layer are injected into the charge transport layer, and then reach the surface and neutralize the positive charge, causing a decrease in surface potential and creating an electrostatic contrast with the unexposed area. . A visible image can be obtained by developing the electrostatic latent image thus formed with a negatively charged toner. This can be directly fixed, or the toner image can be transferred to paper, plastic film, etc. and then developed and fixed. Alternatively, a method may be used in which the electrostatic latent image on the photoreceptor is transferred onto an insulating layer of transfer paper, then developed and fixed. The type of developer, the developing method, and the fixing method may be any known ones or known methods, and are not limited to specific ones. On the other hand, when the charge transport material consists of a hole transport material, the surface of the charge transport layer must be negatively charged.
After charging, when exposed to light, holes generated in the charge generation layer in the exposed area are injected into the charge transport layer, and then reach the surface and neutralize the negative charge, causing a decrease in the surface potential and static electricity between the exposed area and the unexposed area. Electrocontrast occurs. During development, it is necessary to use a positively charged toner, contrary to the case where an electron transport material is used. Another specific example of the present invention is an electrophotographic photoreceptor containing the above-mentioned trisazo pigment and a charge transport material in the same layer. At this time, a charge transfer complex compound consisting of poly-N-vinylcarbazole and trinitrofluorenone can be used in addition to the above-mentioned charge transport substance. The electrophotographic photoreceptor of this example can be prepared by dispersing the aforementioned trisazo pigment and charge transfer complex compound in a polyester solution dissolved in tetrahydrofuran, and forming a film using a coating solution obtained. In any of the photoreceptors, the pigment used contains at least one type of pigment selected from trisazo pigments represented by general formula (1), and its crystal form may be amorphous or crystalline. . In addition, if necessary, two or more types of trisazo pigments represented by the general formula (1) may be used in combination for the purpose of increasing the sensitivity of the photoreceptor or obtaining a bank chromatic photoreceptor by using a combination of pigments with different light absorption. It is also possible to use them in combination or in combination with charge generating substances selected from known dyes and pigments. The electrophotographic photoreceptor of the present invention can be used not only in the photocopying machine, but also in laser printers and CRTs.
Printers, LED printers, LCD printers,
It can also be widely used in electrophotographic applications such as laser engraving. The present invention will be explained below with reference to Examples. Examples 1 to 40 Ammonia aqueous solution of casein (11.2 g of casein, 1 g of 28% ammonia water, 222 ml of water) on an aluminum plate
was applied with a Mayer bar so that the film thickness after drying was 1.0 microns, and dried. Next, 5 g of the above-mentioned exemplified trisazo pigment No. 1
was added to a solution prepared by dissolving 2 g of butyral resin (degree of butyralization: 63 mol %) in 95 ml of ethanol, and dispersed in a sand mill for 2 hours. The dispersion was applied onto the previously formed casein layer using a Mayer bar so that the film thickness after drying was 0.5 microns, and dried to form a charge generation layer. Then, the structural formula 5 g of hydrazone compound and 5 g of polymethyl methacrylate resin (number average molecular weight 100,000) were added to benzene.
A photoreceptor was prepared by dissolving the solution in 70 ml and applying it onto the charge generation layer using a Mayer bar so that the dry film thickness would be 12 microns, and drying to form a charge transport layer. Photoreceptors of Examples 2 to 40 were prepared in the same manner using the azo pigments shown in Table 1 instead of trisazo pigment No. 1. The electrophotographic photoreceptor thus prepared was statically charged with corona at -5kV using an electrostatic copying paper tester Model SP-428 manufactured by Kawaguchi Electric Co., Ltd., and held in a dark place for 1 second, then the illuminance was 2lux. The charging characteristics were measured by exposing the sample to light. As for the charging characteristics, the surface potential (V ₀ ) and the exposure amount E _1/2 (lux·sec) required to attenuate the potential to 1/2 when dark decayed for 1 second were measured. The results are shown in Table 2.

【table】

[Table] Comparative Examples 1 to 4 The central skeletons of exemplified trisazo pigments No. 1, 7, 19, and 30 were

Trisazo pigments having the structure shown in the formula are designated as Comparative Pigments 1 to 4, respectively. A photoreceptor was prepared in exactly the same manner as in Example 1 using Comparative Pigments 1 to 4 in place of the pigment in Example 1,
Charge measurement was carried out. Table 3 shows the characteristics of comparative examples compared to the present invention.

[Table] * Excerpted from the data in Table 2 As is clear from the results in Table 3, the photoreceptor of the present invention is produced by introducing an arylene group with π-electron expansion, such as naphthylene or biphenylene, into the central skeleton of the pigment. It was confirmed that the electrophotographic sensitivity was significantly improved. Examples 41 to 45 and Comparative Examples 5 to 8 Bright area potential and dark area potential during repeated use using the photoreceptors used in Examples 1, 7, 16, 24, and 33 and the photoreceptors used in Comparative Examples 1 to 4 The fluctuation of was measured. The photoreceptor was attached to the cylinder of an electrophotographic copying machine equipped with a -5.6 kV corona charger, an exposure optical system, a developer, a transfer charger, a static elimination exposure optical system, and a cleaner. This copying machine is configured to produce an image on transfer paper as a cylinder is driven. Using this copier, the initial bright area potential (V _L )
and the dark potential (V _D ) are −100V and −600V, respectively.
The bright area potential (V _L ) and the dark area potential (V _D ) were measured after the device was set in the vicinity and used 5000 times. The results are shown in Table 4.

【table】

[Table] The photoreceptor of the present invention had extremely good stability in V _D and V _L even during repeated use. Example 46 On the charge generation layer prepared in Example 1, 2,
A coating solution prepared by dissolving 5 g of 4,7-trinitro-9-fluorenone and 5 g of poly-4,4'-dioxydiphenyl-2,2'-propane carbonate (molecular weight 300,000) in 70 ml of tetrahydrofuran was dried. It was coated at a coating weight of 10 g/m ² and dried. The electrostatic charge of the electrophotographic photoreceptor thus prepared was measured in the same manner as in Example 1. At this time, the charging polarity was set. The results are shown in Table 5. Table 5 V ₀ : 580 volts E _1/2 : 6.3 lux·sec Example 47 A polyvinyl alcohol film having a thickness of 0.5 microns was formed on the aluminum surface of an aluminum vapor-deposited polyethylene terephthalate film. Next, the dispersion of the trisazo pigment used in Example 1 was applied onto the previously formed polyvinyl alcohol layer using a Mayer bar so that the film thickness after drying was 0.5 microns, and dried to form a charge generating layer. was formed. Then, the structural formula 2.5g of stilbene derivative and structural formula shown as A solution prepared by dissolving 2.5 g of pyrazoline compound and 5 g of polyarylate resin (condensation polymer of bisphenol A and terephthalic acid-isophthalic acid) in 70 ml of tetrahydrofuran is placed on the charge generation layer so that the film thickness after drying is 10.
It was applied to a micron thickness and dried to form a charge transport layer. The charging characteristics and durability characteristics of the photoreceptor thus prepared were measured in the same manner as in Examples 1 and 41. The results are shown in Table 6. Table 6 V ₀ : 600V E _1/2 : 4.9lux・sec Durability characteristics Initial state After 5000 sheets of durability V _D V _L V _D V _L −600V −100V −620V −120 From the results in Table 6, the photosensitivity of the present invention The body has good sensitivity and good potential stability during long-term use. Examples 43 to 48 An ammonia aqueous solution of casein was coated on an aluminum plate with a thickness of 100 microns and dried to form a subbing layer with a thickness of 0.5 microns. Next, 5 g of 2,4,7-trinitro-9-fluorenone and 5 g of poly-N-vinylcarbazole (number average molecular weight 300,000) were added to 70 ml of tetrahydrofuran.
to form a charge transfer complex. This charge transfer complex compound and the above-mentioned trisazo pigment No.
(26) 1 g was added to a solution in which 5 g of polyester resin (manufactured by Byron Toyobo) was dissolved in 70 ml of tetrahydrofuran, and dispersed. This dispersion was applied onto the undercoat layer so that the film thickness after drying was 12 microns, and dried. The charging characteristics and durability characteristics of the photoreceptors thus prepared were measured in the same manner as in Examples 1 and 41. The results are shown in Table 7. However, the charging polarity was determined. Table 7 V ₀ : 590V E _1/2 : 5.6lux・sec Durability characteristics Initial state After 5000 sheets durability V _D V _L V _{D V L} +600 +110 +615 +125 Example 49 Casein layer used in Example 1 was applied A photoreceptor was prepared in the same manner as in Example 1, except that the charge transport layer and charge generation layer of Example 1 were sequentially laminated on the casein layer of the aluminum substrate, and the order of the layer structure was different. The charge was measured. However, the charging polarity was determined. Charging characteristics are shown in Table 8. Table 8 V ₀ : 590V E _1/2 : 5.0lux・sec

Claims (1)

[Claims] First-order general formula (1) (In the formula, Ar ₁ , Ar ₂ and Ar ₃ each represent an arylene group or a divalent heterocyclic group which may have a substituent, and at least one of Ar ₁ , Ar ₂ and Ar ₃ is naphthylene, biphenylene, (A is a group selected from the group consisting of anthricane and a divalent heterocyclic group, and A represents a coupler residue having a phenolic OH group.) The photosensitive layer is characterized by containing a trisazo pigment represented by Electrophotographic photoreceptor. 2 A in the above general formula (1) is the following general formula (2) to (8) (In the formula, X is a residue that is fused with a benzene ring to form a polycyclic aromatic ring or a heterocycle; R ₃ and R ₄ are hydrogen,
Alkyl, aralkyl, aryl or heterocyclic group which may have a substituent or a group which is bonded to each other to form a cyclic amino group with a nitrogen atom; R ₅ and R ₆ are alkyl which each may have a substituent;
Aralkyl, aryl group; Y is a divalent aromatic hydrocarbon group or a divalent heterocyclic group having a nitrogen atom; R ₇ is an aryl or heterocyclic group that may have a substituent; R ₈ and R ₉ represents an alkyl, aralkyl, aryl or heterocyclic group which each may have a substituent. ) The electrophotographic photoreceptor according to claim 1. 3 The photosensitive layer is a functionally separated type having a charge generation layer and a charge transport layer, and the charge generation layer has the general formula
An electrophotographic photoreceptor according to claim 1, which contains an azo pigment represented by (1). 4 R ₃ in the above general formula (2) is hydrogen, and R ₄
is the general formula (In the formula, R ₁₀ represents a substituent selected from the group consisting of halogen, nitro, cyano, and trifluoromethyl.) The electrophotographic photoreceptor according to claim 2, which is a substituted phenyl group represented by the following formula.