JPH01191154A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To decrease potential fluctuation at and under a high temp. and high humidity by incorporating a specific disazo pigment into a photoconductive layer. CONSTITUTION:This electrophotographic sensitive body contains the disazo pigment expressed by formula I in the photoconductive layer. In formula I, a and A' denote an arom. hydrocarbon ring or arom. heterocycle which may be bonded via a combination group and may have a substituent; R1 and R2 denote a residual amide group, etc., which may have a substituent; X denotes a divalent arom. hydrocarbon ring group, etc., which may have a substituent; Y and Y' denote a polyclic arom. ring, etc., by condensing to a benzene ring. The pigment expressed by formula I-1 is exemplified as the representative example of the disazo pigment expressed by formula I in this embodiment. Either or both of the carrier generation efficiency and carrier transfer efficiency in the photoconductive layer contg. the disazo pigment are thereby improved and the electrophotographic sensitive body which has a practicably with sensitivity characteristic, stable potential characteristic in repetitive use and decreased potential fluctuation particularly at and under the high temp. and high humidity is thereby obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a novel electrophotographic photoreceptor, and more particularly to an electrophotographic photoreceptor containing a disazo pigment having a specific molecular structure in a photoconductive layer.

[Prior Art 1] Pigments and dyes exhibiting photoconductivity have been published in numerous publications.

For example, “RCA Review” Vol. 23, P.
, 413-P, 419 (1962, 9), the photoconductivity of phthalocyanine pigments was published, and electrophotographic photoreceptors using these phthalocyanine pigments were disclosed in U.S. Pat. No. 3,397,086 and U.S. Pat. No. 3,816.
It is described in the specification of No. 118, etc. In addition, examples of organic semiconductors used in electrophotographic photoreceptors include US Pat. No. 4,315,983 and US Pat. No. 4,32716.
9 specification and “Re5each Discl.

5ure" 20517 (1981, 5); squaric acid methine dyes described in U.S. Pat. No. 3,824,099;
U.S. Patent No. 3,898,084, U.S. Patent No. 425
Examples include disazo pigments described in the specification of No. 1613 and the like.

Such organic semiconductors are easier to synthesize than inorganic semiconductors and can be synthesized as compounds that have photoconductivity for light in the required wavelength range. Electrophotographic photoreceptors formed on conductive substrates have the advantage of improved color sensitivity, but only a few of them are practical in terms of sensitivity and durability.

Pigments with a structure in which monoazo is connected with a coupler are described, for example, in JP-A-56-150751, but since there are few conjugated parts in the structure, there are no pigments that have high sensitivity up to the practical wavelength range. Very little.

Also, there are only a few that can be used under harsh conditions.

[Problem B to be Solved by the Invention] The purpose of the present invention is to provide a novel photoconductive material that can be used in all current electrophotographic processes, has practical high-sensitivity characteristics, and is suitable for repeated use. An object of the present invention is to provide an electrophotographic photoreceptor having stable potential characteristics.

[Means for Solving the Problems, Effects] The present invention is an electrophotographic photoreceptor having a photoconductive layer on a conductive substrate, characterized in that the photoconductive layer contains a disazo pigment represented by the following general formula (1). It consists of an electrophotographic photoreceptor.

In the general formula, A and Ao represent an aromatic hydrocarbon ring or an aromatic heterocycle which may have a substituent which may be bonded via a bonding group, and A and A' are the same and may also be different.

R1 and R2 represent an amide residue, a cyclic amide residue, a ureido group, a hydrazide residue, or a cyclic hydrazide residue which may have a substituent, and R1 and R2 may be the same or different.

X represents a divalent aromatic hydrocarbon ring group or alkenylene group which may have a substituent.

Y and Yo represent residues necessary to form a polycyclic aromatic ring or a heterocycle by condensation with a benzene ring, and Y and Y' may be the same or different.

Specifically, A and Ao include two aromatic hydrocarbon rings such as benzene, naphthalene, fluorene, anthracene, and pyrene, furan, thiophene, pyridine, indole, benzothiazole, carbazole, acridone, dibenzothiophene, benzoxazole, Aromatic heterocycles such as benzotriazole, oxadiazole, thiadiazole, etc., and those in which the above aromatic rings are bonded directly or with an aromatic group or a non-aromatic group, such as triphenylamine, diphenylamine, N-methyldiphenylamine, biphenyl , terphenyl, binaphthyl, fluorenone, phenanthrenequinone, anthraquinone, benzanthrone, diphenyloxadiazole, phenylbenzoxazole, diphenylmethane, diphenylsulfone, diphenyl ether, benzophenone, dithylben, distyrylbenzene, tetraphenyl-p-phenylenediamine, Examples include monovalent organic groups derived from tetraphenylbenzidine and the like.

R1 and R2 are monovalent or divalent amide residues such as methylamide, phenylamide, diphenylamide, cyclic amide residues such as piperidide and morpholide, N
o-methylureido, N.

-Ureido residues such as phenylureido, N'-ethylidene hydrazide, No-benzylidene hydrazide, No.
- hydrazide residues such as fluorenylidene hydrazide, No-methyl hydrazide, No-phenyl hydrazide,
Examples include cyclic hydrazide residues such as piperidinamide and morpholinoamide.

Examples of X include aromatic hydrocarbon ring groups such as phenylene, naphthylene and biphenylene, and fullkenylene groups such as vinylene, propenylene and butadienylene.

Examples of Y and Y' include polycyclic aromatic rings or heterocycles bonded to a benzene ring, such as a naphthalene ring, an anthracene ring, a carbazole ring, a benzocarbazole ring, a dibenzofuran ring, a dibenzonaphthofuran ring, and a diphenylene sulfide ring.

The above A, A', R1, R2, X, Yt3 and Y.

Substituents include methyl, ethyl, propyl,
Alkyl groups such as isopropyl and butyl, heptalyl groups such as phenyl, tolyl, biphenyl, and naphthyl, halogen atoms such as fluorine, chlorine, iodine, and bromine, alkoxy groups such as methoxy, nidoxy, and propoxy, cyano groups, Examples include nitro groups, halomethyl groups, acyl groups such as acetyl and benzoyl, and cyclic amino groups such as phenylamino and diethylamino.

Typical specific examples of the disazo pigment represented by the general formula (1) of the present invention are listed below.

Exemplary Pigment (1) Exemplary Pigment (2) Exemplary Pigment (3) -N-N-A' Exemplary Pigment (4) Exemplary Pigment (5) A: 0UN-@-°: -o-OCHs
Exemplary Pigment (6) -N-N-A' Exemplary Pigment (8) Exemplary Pigment (9) Exemplary Pigment (10) Exemplary Pigment (11) -N-N-A' A: 0 N -ol: +0CHs Exemplary pigment (12) A, A': -@-CM Exemplary pigment (13) Exemplary pigment (14) Exemplary pigment (15) Exemplary pigment (16) A, A l: -@-0CHJ Exemplary pigment (17) -N -N-A' A, A': -@-NO exemplified pigment (18) -N1N-A' A, A'': +M (CzH da) exemplified pigment (19) exemplified pigment (20) exemplified pigment (21 ) Exemplary Pigment (22) Exemplary Pigment (23) Exemplary Pigment (24) Exemplary Pigment (25) A, A':■ Pigment (30) Synthesis Example (Synthesis of Exemplary Pigment (12)) In a 100 mfL beaker, 50 m!L of water, 12 ml of concentrated hydrochloric acid,
34 mJL (0.140%) was added thereto, and while cooling in an ice-water bath, 5 g (0.042 mol) of IL was added thereto, and the liquid temperature was brought to 3° C. while stirring.

Next, a solution of 3.04 g (0,044 mol) of sodium nitrite dissolved in 6 mJL of water was added dropwise over 10 minutes while controlling the liquid temperature to below 5°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 0 reaction solution and filtered, and then a solution of 9.24 g (0,084 mol) of sodium borofluoride dissolved in 18 mM of water was added dropwise, and the precipitated borofluoride salt was collected by filtration, washed with water, and then dried in vacuum. .

Yield 6.29g, yield 69.06% Next, 300! Pour 140 mJl of DMF into an L beaker, dissolve 4.85 g (0,009 mol) in it, and lower the liquid temperature to 5°C.
After cooling to a temperature of
018 mol) was added dropwise over 10 minutes, and then stirred for 2 hours. After filtering the reaction solution, N,N-dimethylformamide 1
The mixture was washed 5 times with 40 mJL, replaced with acetone, and vacuum dried to obtain the desired azo pigment.

Yield 7.17g, yield 84.45% (borofluoride salt base) Elemental analysis Calculated value (%) Actual value (%) C74.9
975,04 H3,023,03 N 13.99 13.93 - In the shell, (wherein X, R1, R2, Y and Y' are the general formula (1)
(synonymous with) by the above method.

Coatings with the aforementioned disazo pigments exhibit photoconductivity and can therefore be used in photoconductive layers of subsequent electrophotographic photoreceptors.

That is, in a specific example of the present invention, an electrophotographic photoreceptor is prepared by forming a film of the above-mentioned disazo pigment on a conductive substrate by vacuum evaporation, or by dispersing it in a suitable binder and forming a film. be able to.

In a preferred embodiment of the present invention, the photoconductive coating described above can be applied as a charge generation layer in an electrophotographic photoreceptor in which the photoconductive layer of the electrophotographic photoreceptor is functionally separated into a charge generation layer and a charge transport layer. .

The charge generation layer contains as much of the aforementioned photoconductive disazo pigment as possible in order to obtain sufficient absorbance and to shorten the migration time of the generated charge carriers.
A thin film layer, for example a thin film layer having a thickness of 5 or less, preferably 0.01 to 1%, is preferred.

This means that most of the incident light is absorbed by the charge generation layer and generates a large number of charge carriers, and that the generated carriers must be injected into the charge transport layer without being deactivated by recombination or trapping. It is caused by something.

The charge generation layer can be formed by dispersing the disazo pigment in a suitable binder and coating it on a conductive substrate, or can be obtained by forming a deposited film using a vacuum deposition apparatus.

The binder that can be used to form the charge generating layer by coating can be selected from a wide variety 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, polyester, phenoxy resin, polyvinyl acetate, acrylic resin, polyacrylamide, polyamide, polyvinylpyridine, cellulose resin, polyurethane, epoxy resin , casein, polyvinyl alcohol,
Examples include insulating resins such as polyvinylpyrrolidone.

The resin contained in the charge generation layer is suitably 80% by weight or less, preferably 40% by weight or less.

The solvent that dissolves these resins varies depending on the type of resin, and is preferably selected from those that do not dissolve the charge transport layer and undercoat layer described below.

Specific organic solvents include methanol, ethanol,
Alcohols such as Impropatool, ketones such as acetone, methyl ethyl ketone, cyclohexanone, N
, amides such as N-dimethylformamide and 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 halogenated hydrocarbons such as chloroform, methylene chloride, dichloroethylene, carbon tetrachloride, and trichloroethylene, or benzene, toluene, xylene, ligroin, monochlorobenzene, dichlorobenzene, etc. aromatic hydrocarbons and the like can be used.

Coating methods include dip coating method, spray coating method, spinner coating method, bead coating method, Meyer bar coating method, plate coach ink method,
This can be carried out using a coating method such as a roller coating method or a curtain call coating method.

Drying is preferably carried out by drying to the touch at room temperature and then heating. Drying by heating is performed at a temperature of 30 to 200°C for 5 minutes to
It can be carried out stationary or under blown air for a time in the range of 2 hours.

The charge transport layer is electrically connected to the charge generation layer described above, and has the function of receiving and taking charge carriers injected from the charge generation layer in the presence of an electric field, and transporting these charge carriers to the surface. have. 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 referred to as charge transport material) is substantially in the wavelength range of electromagnetic waves to which the charge generation layer is sensitive. The electromagnetic radiation referred to herein, which is preferably insensitive, encompasses the broad definition of light, including gamma rays, xlla, ultraviolet rays, visible light, near infrared rays, infrared rays, far infrared rays, and the like.

When the photosensitive wavelength range of the charge transport layer coincides with or overlaps that of the charge generation layer, charge carriers generated in both layers trap each other, resulting in a decrease in sensitivity.

Charge transporting substances include electron transporting substances and hole transporting substances, and electron transporting substances include chloranil, tetracyanoethylene, tetracyanoquinodimethane, 2,4,
5.7-tetranitro-9-fluorenone, 2,4,5
．． Examples include electron-withdrawing substances such as 7-titranitroxanthone and 2,4.8-)linitrothioxanthone, and polymerized versions of these electron-withdrawing substances.

Examples of hole-transporting substances include pyrene, N-ethylcarbazole, N-isopropylcarbazole, and N-methyl-N-
Phenylhydrazino-3-methylidene-9-ethylcarbazole, N,N-diphenylhydrazino-3-methylidene-9-ethylcarbazole, N,N-diphenylhydrazino-3-methylidene-10-ditylphenothiazine, N, N-diphenylhydrazino-3-methylidene-
1O-Nitylphenoxazine, p-diethylaminobenzaldehyde-N, N-diphenylhydrazone, p-diethylaminobenzaldehyde-N-α-naphthyl-N
-Phenylhydrazone, p-pyrrolidinobenzaldehyde N, N-diphenylhydrazone, 1,3.3-)samethylindolenine-ω-aldehyde-N,N-diphenylhydrazone, p-diethylbenzaldehyde-3-
Hydrazones such as methylbenzthiazolinone-2-hydrazone, 2,5-bis(p-diethylaminophenyl)-1,3,4-oxadiazole, ■-phenyl-3
-(p-diethylaminostyryl)-5-(p-diethylaminophenyl)pyrazoline, l-[quinylyl (2)
]-3-(p-diethylaminostyryl)-5-(p-
diethylaminophenyl)pyrazoline, 1-[pyridyl(2)]-3-(p-diethylaminostyryl)-5-
(p-diethylaminophenyl)pyrazoline, l-[6
-Medoxybilidyl(2)] -3-(p-diethylaminostyryl) -5,-(p-diethylaminophenyl)pyrazoline, 1-[pyridyl(3)]-3-(p
-diethylaminostyryl)-5-(p-diethylaminophenyl)pyrazoline, 1-[Revidyl (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)hilazoline, 1-phenyl-3-(α-
benzyl-P-diethylaminostyryl)-5-(P-
pyrazolines such as diethylaminophenyl)pyrazoline and spiropyrazoline, 2-(P-diethylaminostyryl)-6-dinithylaminobenzoxazole, 2-
Oxazole compounds such as (p-diethylaminophenyl)-4-(p-dimethylaminophenyl)-5-(2-chlorophenyl)oxazole, thiazoles such as 2-(p-diethylaminostyryl)-6-dinithylaminobenzothiazole triarylmethane compounds such as bis(4-diethylamino-2-methylphenyl)-phenylmethane, 1゜1-bis(4-N,N
-diethylamino-2-methylphenyl)hebutane, 1
．． 1.2. Boarylalkanes such as 2-tetrakis(4-N,N-dimethylamino-2-methylphenyl)ethane, stilbene compounds such as β-phenyl-p-diphenylaminostilbene, α-phenyl-4- N,
N-diphenylaminostilbene-N-dithyl-3-(
styryl compounds such as α-phenylstyryl) carbazole, 9-dibenzylaminobenzylidene-9H-fluorenone, 5-P-ditolylaminobenzylidene-5H-dibenzo[a, d-cocyclohebutene, triphenylamine, poly-N -Vinylcarbazole, polyvinylpyrene, polyvinylanthracene, polyvinylacridine, poly-9-vinylphenylanthracene.

Pyrene-formaldehyde resin, ethylcarbazole-
Examples include formaldehyde resin.

In addition to cholera organic charge transport materials, inorganic materials such as selenium, selenium-tellurium, amorphous silicon, cadmium sulfide, etc. can also be used.

Further, these charge transport materials can be used alone or in combination of two or more.

When the charge transport material does not have film-forming properties, a film can be formed by selecting an appropriate binder. Examples of resins that can be used as binders include acrylic resin,
polyarylate, polyester, polycarbonate, polystyrene acrylonitrile-styrene copolymer,
Examples include insulating resins such as acrylonitrile-butadiene copolymer, polyvinyl butyral, polyvinyl formal, polysulfone, polyacrylamide, polyamide, chlorinated rubber, and organic photoconductive polymers such as poly-N-vinylcarbazole polyvinylanthracene and polyvinylpyrene.

The charge transport layer cannot be made thicker than necessary because there is a limit to how much charge carriers can be transported. When forming the charge transport layer by coating, an appropriate coating method as described above can be used.

A photoconductive layer having such a laminated structure of a charge generation layer and a charge transport layer is provided on a conductive substrate. As the conductive substrate, materials whose substrates themselves are conductive, such as aluminum, aluminum alloy, copper, zinc, stainless steel, vanadium, molybdenum, chromium, titanium, nickel, indium, gold, and platinum, are used.

In addition, plastics (e.g., polyethylene, polypropylene, polyvinyl chloride, polyethylene terephthalate, acrylic resin, polyfluoride, ethylene chloride, etc.), conductive substrates made of plastic coated with conductive particles (e.g. carbon black, silver particles, etc.) together with a suitable binder, conductive substrates made of plastic or paper impregnated with conductive particles, and conductive polymers. It is possible to use plastics that have

An undercoat layer having barrier and adhesive functions can also be provided between the conductive substrate and the photosensitive layer.

The subbing layer can be formed from 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 subbing layer is 0.1 to 5 pL, preferably 0.
．． 5 to 3 liters is appropriate.

When using a photoreceptor in which a conductive substrate, a charge transport layer, and a charge generation layer are laminated in this order, and the charge transport substance is an electron transport substance, the surface of the charge generation layer must be negatively charged, and after charging, Upon exposure, electrons generated in the charge generation layer in the exposed portion are injected into the charge transport layer, and then reach the substrate.

On the other hand, holes generated in the charge generation layer reach one surface, attenuation of the surface potential occurs, and electrostatic contrast occurs between the surface potential and the unexposed area.

A visible image is obtained by developing the electrostatic latent image thus formed with a positively charged toner.

This can be directly fixed, or the toner image can be transferred to paper or plastic film 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, and then visualized and fixed. The type of developer, the developing method, and the fixing method may be any known ones or methods, and are not limited to specific ones.

On the other hand, when the charge generation layer is made of a hole transporting substance, the surface of the charge generation layer must be positively charged, and when exposed to light after charging, holes generated in the charge generation layer are injected into the charge transport layer in the exposed area. and then reaches the substrate. On the other hand, the electrons generated in the charge generation layer reach one surface, the surface potential attenuates, and electrostatic contrast occurs between the surface potential and the unexposed area. During development, it is necessary to use a negatively charged toner, contrary to when an electron transporting substance is used.

Further, in another specific example of the present invention, the above-mentioned hydrazones,
Organic photoconductive substances such as pyrazolines, oxazoles, thiazoles, triarylmethanes, polyarylalkanes, triphenylamine, poly-N-vinylcarbazoles, and inorganic photoconductive substances such as zinc oxide, cadmium sulfide, and selenium. A photosensitive film may be prepared containing the disazo pigment as a sensitizer. This photosensitive film is formed by coating these photoconductive substances and the disazo pigment together with a binder.

In addition, as another specific example of the present invention, the above general formula (1)
Examples include an electrophotographic photoreceptor containing a disazo pigment represented by the following in the same layer together with a charge transporting substance. 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 disazo pigment and charge transfer complex compound in a polyester solution dissolved in tetrahydrofuran, and then forming a film thereon.

The pigment used in any electrophotographic photoreceptor contains at least one type of pigment selected from disazo pigments represented by general formula (1), and its crystal form may be amorphous or crystalline. .

In addition, if necessary, pigments with different light absorptions may be used in combination to increase the sensitivity of the photoreceptor, or two or more types of disazo pigments represented by general formula (1) may be combined for the purpose of obtaining a panchromatic photoreceptor. Alternatively, it can be used in combination with a charge generating substance selected from known dyes and pigments.

The electrophotographic photoreceptor of the present invention can be used not only for electrophotographic copying machines, but also for laser printers, CRT printers, L
It can also be widely used in electrophotographic applications such as ED printers, liquid crystal printers, and laser engraving.

[Example] Examples 1 to 25 Ammonia aqueous solution of casein (casein 1
1.2 g of ammonia water, 1 g of ammonia water, and 222 m of water) was applied using a Mayer bar so that the film thickness after drying was 1.0 p, and then dried.

Next, 5 g of Exemplary Pigment (1) was added to a solution prepared by dissolving 2 g of butyral resin (degree of butyralization: 85 mol %) in 95 mJ1 of ethanol, and dispersed in a sand mill for 2 hours. This dispersion is applied onto the previously formed casein layer so that the film thickness after drying is 0.
．． A charge generating layer was formed by applying 8 g using a Mayer bar and drying.

Next, 5 g of a hydrazone compound with the structural formula and polymethyl methacrylate (
5 g of average molecular weight filO) was dissolved in 70 ml of benzene, and this was applied onto the charge generation layer using a Mayer bar so that the film thickness after drying was 20 g, and dried to form a charge transport layer. An electrophotographic photoreceptor of No. 1 was prepared.

Examples 2 to 2 using other exemplary pigments in place of exemplary pigment (1)
An electrophotographic photoreceptor corresponding to No. 5 was prepared in exactly the same manner.

The electrophotographic photoreceptor thus prepared was tested using an electrostatic copying paper tester (Model 5P-428, manufactured by Kawaguchi Denki ■).
corona charging at -5KV using a static method,
After being kept in a dark place for 1 second, it was exposed to light at an illuminance of 2 lux, and the charging characteristics were examined.

The charging characteristics are 1 surface level (Vo) and the exposure amount (E) required to attenuate the potential by 1/2 when dark decaying for 1 second.
l/2) was measured. Show the results.

/, V −V El/2
1uxgec1 (1) 890
2.52 (3) 700
2.23 (4) 700 2
．． 04 (5) 710 3.4
5 (6) 700 2.16
(7) 690 3.67
(8) 690 4.38
(9) 700 3.29 (11)
710 4.410 (12)
700 3.811 (13)
700 2.612 (14) 6
90 2.313 (15) 700
2.014 (16) 700
2.715 (17) 700 3
．． 416 (18) 690 3.8
17 (19) 710 3.918
(21) 700 4.219
(23) 700 3.420 (
25) 710 2.321 (2
6) 700 2.822 (27)
690 2.923 (28)
700 4.124 (29)
690 4.025 (30)
700 4.3 Comparative Examples 1 to 3 The following azo pigments were used in place of exemplified pigment (1).

An electrophotographic photoreceptor was produced in the same manner as in Example 1 except for this. The charging characteristics of this electrophotographic photoreceptor were measured in the same manner as in Example 1. Show the results.

(Comparative example 1 corresponding to Example 11) Azo pigment vO knee 680V El/2: 5.8 x uX, 5ec (Comparative example 2 corresponding to Example 20) Azo pigment vO knee 870V El/2: 7.0JLux , 5ec (Comparative Example 3 corresponding to Example 23) Azo pigment vo knee 690V El/2: 8.1lux, sec Examples 26 to 30 Electrophotographic photoreceptor prepared in Example 1.3.10.16.21 Fluctuations in bright and dark potentials were measured during repeated use.

As a method, the photoreceptor was attached to the cylinder of an electrophotographic copying machine equipped with a -5.6 KV corona belt, an exposure optical system, a developing device, 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 the cylinder is driven.

Using this copying machine, the initial bright area potential (VL) and dark area potential (Vo) were set to -170V and -700V, respectively.
Bright area potential (V
L) and dark potential (Vo) were measured. Also, temperature 3
Initial and 5,000 ℃ under conditions of 2.5℃ and 85% humidity
VL and VD after 0-sheet durability were also measured. Show the results.

[Standard conditions] [Temperature: 32.5°C, humidity: below 85%] Comparative Examples 4 and 5 Electrophotographic sensitization was carried out in exactly the same manner as in Example 1, except that the following azo pigment was used in place of exemplified pigment (1). A light area potential (VL) during repeated use was prepared in the same manner as in Example 26.
) and dark potential (Vo) were measured. Show the results.

(Comparative example 4 corresponding to Example 28) Azo pigment (N) (Comparative example 5 corresponding to Example 27) Azo pigment [Standard conditions] [Temperature 32.5°C, humidity 85% below] It can be seen that the electrophotographic photoreceptor of the invention has little potential fluctuation, especially under high temperature and high humidity conditions.

Example 31 5 g of 2.4.7-dolinitro-9-fluorenone and poly-4,4'-dioxydiphenyl-2,2-propane carbonate (molecular weight: 300,000) were placed on the charge generation layer formed in Example 1. The coating amount after drying the coating solution prepared by dissolving 5g in 70mJL of tetrahydrofuran is 10g/m2
It was applied 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 to ten. Show the results.

vo:+700V El/2:2.2! ; Lux, sea Example 32 A polyvinyl alcohol film with a film thickness of o and sIL was formed on the aluminum surface of an aluminum vapor-deposited polyethylene terephthalate film. A charge generation layer was formed on the alcohol layer using a Mayer bar so that the film thickness after drying was 0.5 tile and dried.

Next, 5 g of a pyrazoline compound with the structural formula and 5 g of polyarylate (condensation polymer of bisphenol A and terephthalic acid-isophthalic acid)
A solution obtained by dissolving the above in 70 mfL of tetrahydrofuran was applied onto the charge generation layer so that the film thickness after drying was 10μ, and dried to form a charge transport layer. The charging characteristics and durability characteristics of the electrophotographic photoreceptor thus prepared were measured in the same manner as in Examples 1 and 26. Show the results.

V□Knee 700V El/2: 2.4fLux, sec Durability characteristics Initial Vo Knee 700V vL Knee 170V After 5,000 sheets durability VO Knee 690V VL Knee 180V From the above results, the sensitivity is good and the potential stability during durable use is also good.

Example 33 An ammonia aqueous solution of casein (described above) was coated on an aluminum plate with a thickness of toop and dried to form a subbing layer with a thickness of 0.5 mm.

Next, 5 g of 2,4.7-dolinitro-9-fluorenone
A charge transfer complex compound was prepared by dissolving 5 g of poly-N-vinylcarbazole (number average molecular weight: 300,000) in 70 ml of tetrahydrofuran.

This charge transfer complex compound and 1 g of Exemplary Pigment (2) were added to a solution in which 5 g of polyester (trade name: Vylon, manufactured by Toyobo ■) was dissolved in 70 ml of tetrahydrofuran, and dispersed. This dispersion was applied onto the undercoat layer and dried to form a layer of 12 IL to produce an electrophotographic photoreceptor.

The electrophotographic properties of this electrophotographic photoreceptor were measured in the same manner as in Example 1. However, the charging polarity was set to 10. Show the results.

vo: +700V El/2: 2.71ux, sec Example 34 The same charge transport layer and charge generation layer as in Example 1 were sequentially laminated on the casein layer of the casein layer-coated aluminum substrate used in Example 33. An electrophotographic photoreceptor was prepared in exactly the same manner as in Example 1, except for the layer structure, and the charging characteristics were measured in the same manner as in Example 1.

However, the charging polarity was set to 10. Show the results.

vo: +700V El/2: 2.8fLux, sec Example 35 Electrophotography was carried out in the same manner as in Example 1, except that 5 g of the benzylidene compound below was used as a charge transport material in place of the hydrazone compound used in Example 1. A photoreceptor was prepared, and its charging characteristics were measured in the same manner as in Example 1. Show the results.

vo knee 700V El/2: 2.31ux, sec [Effect of the invention] The electrophotographic photoreceptor of the present invention contains a specific disazo pigment in the photoconductive layer, so that the inside of the photoconductive layer containing the disazo pigment is It is estimated that either one or both of carrier generation efficiency and carrier transport efficiency is improved, and it has high sensitivity and excellent potential stability during long-term use. It is an electrophotographic photoreceptor that exhibits little potential fluctuation, especially under high temperature and high humidity conditions.

Claims (1)

[Scope of Claims] 1. An electrophotographic photoreceptor having a photoconductive layer on a conductive substrate, characterized in that the photoconductive layer contains a disazo pigment represented by the following general formula (1). . General formula ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (1) In the formula, A and A' are aromatic hydrocarbon rings or aromatic rings that may have substituents that may be bonded via a bonding group. It represents a heterocycle, and A and A' may be the same or different. R_1 and R_2 represent an amide residue, a cyclic amide residue, a ureido group, a hydrazide residue, or a cyclic hydrazide residue that may have a substituent, and R_1 and R_2 may be the same or different. X represents a divalent aromatic hydrocarbon ring group or alkenylene group which may have a substituent. Y and Y' represent residues necessary to form a polycyclic aromatic ring or a heterocycle by condensation with a benzene ring, and Y and Y' may be the same or different.