JPS63172163A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To maintain a practicable high sensitivity characteristic and stable potential characteristic in repetitive use by incorporating a specific disazo pigment into a photoconductive layer. CONSTITUTION:This electrophotographic sensitive body contains the disazo pigment expressed by the formula in the photoconductive layer. In the formula, R1 denotes a hydrogen atom, alkyl group, aryl group, aralkyl group, alkoxy group of halogen atom, nitro group and cyano group, R2, R3, R4 and R5 denote a hydrogen atom or electron withdrawing group A and A' denote a coupler residue having a phenolic hydroxy group; A and A' may be the same or different, Ar1, Ar2, Ar3 and Ar4 denote a carbon cyclic arom. ring group or substed. or unsubstd. heterocyclic arom. ring group; Ar1, Ar2, Ar3, Ar4 may be the same of different. The electrophotographic sensitive body having the high sensitivity and the excellent potential stability during long-term use is thereby obtd. and the good image having no fogging is obtd. with high sensitivity even in the oscillation wavelength region of a semiconductor laser.

Description

Detailed Description of the Invention [Field of Industrial Application] 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 its photoconductive layer. .

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

For example, “RCA Review” Vol. 23,
P, 413-P, 419 (1962, 9) have published on the photoconductivity of phthalocyanine pigments, and electrophotographic photoreceptors using these phthalocyanine pigments have been published in U.S. Pat. No. 3,397,086 and U.S. Pat. No. 381.
It is described in Publication No. 8118 and the like. Other organic semiconductors used in electrophotographic photoreceptors include, for example, US Pat. No. 4,315,983.

U.S. Patent No. 4327169 and “Re5eachD”
Byrylium dyes described in US Pat. No. 3,824 (1981, 5)
Squaric acid methine dyes described in US Pat. No. 099, US Pat. No. 3,898,084, and US Pat. No. 4
Examples include disazo pigments described in Japanese Patent No. 251613 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. An electrophotographic photoreceptor formed on a conductive support has the advantage of improved color sensitivity;
It has problems with sensitivity and durability.

[Problems 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 and has practical high-sensitivity characteristics and An object of the present invention is to provide an electrophotographic photoreceptor having stable potential characteristics during use.

[Means and effects for solving the problems] The present invention provides an electrophotographic photoreceptor having a photoconductive layer,
It is composed of an electrophotographic photoreceptor characterized in that the photoconductive layer contains a disazo pigment represented by the following general formula (1).

General formula (1) % formula % In the formula, R1 represents a hydrogen atom, an alkyl group that may have a substituent, an aryl group, an aralkyl group, an alkoxy group, a halogen atom, a nitro group, a cyano group, R2, R3
, R4 and R5 represent a hydrogen atom or an electron-withdrawing group, A and Ao represent a coupler residue having a phenolic hydroxyl group, A and A' may be the same or different; , A3 and Ar4 represent a substituted or unsubstituted carbocyclic aromatic ring group or a substituted or unsubstituted heterocyclic aromatic ring group, and Ar4 , Ar
2, A3, and A4 may be the same, and the atte may also be different.

Specifically, R1 is methyl, ethyl, propyl, isopropyl, butyl, S-butyl, t-butyl, methoxy,
Groups such as ethoxy, propoxy, phenoxy, phenyl, p-tolyl, benzyl, phenethyl, naphthylmethyl, fluorine atom, chlorine atom, bromine atom, iodine atom, nitro, and cyano are mentioned, and substituents include fluorine atom,
Halogen atoms such as chlorine atoms, bromine atoms, iodine atoms,
Alkyl groups such as methyl, ethyl, propyl, butyl,
Alkoxy groups such as methoxy, ethoxy, propoxy, phenoxy, nitro group, cyano group, dimethylamino, diethylamino, dibenzylamino, diphenylamino,
Examples include substituted amine groups such as morpholino, piperidino, and pyrrolidino.

The electron-withdrawing group in R2-R5 is a fluorine atom,
Halogen atoms such as chlorine atoms, bromine atoms, iodine atoms,
Indicates a cyano group and a nitro group.

More preferred specific examples of coupler residues having A and 8° phenolic hydroxyl groups include the following general formulas (2) to (8).
) are included.

X′ In the formula, X is condensed with a benzene ring to form a polycyclic aromatic ring or heterocycle such as a naphthalene ring, anthracene ring, carbazole ring, benzcarbazole ring, dibenzofuran ring, dibenzonaphthofuran ring, or diphenylene sulfide ring. Residues required for are shown.

The ring to which X is bonded is more preferably a naphthalene ring, an anthracene ring, a carbazole ring, or a benzcarbazole ring.

R6 and R7 are a hydrogen atom, an alkyl group that may have a substituent, an aryl, an aralkyl group, a heterocyclic group, or R
6, represents a cyclic amino group together with the nitrogen atom to which R7 is bonded.

Specific examples of alkyl groups include methyl, ethyl, propyl, and butyl; specific examples of aralkyl groups include benzyl, phenethyl, and naphthylmethyl; specific examples of aryl groups include phenyl, diphenyl, naphthyl, anthryl, and heterocyclic rings. Specific examples of the group include carbazole, dibenzofuran, thiazole, and pyridine.

In the general formula, R8 and R9 represent a hydrogen atom, an alkyl group that may have a substituent, an aryl group, or an aralkyl group @ R
Specific examples of s and R9 are shown by the same examples as for R6 and R7 above.

The alkyl group, aryl group, aralkyl group, alkoxy group, and heterocyclic group represented by the substituents R6 to R9 in general formulas (2) to (4) may further include other substituents such as a fluorine atom, a chlorine atom, an iodine atom, Halogen atoms such as bromine atoms, alkyl groups such as methyl, ethyl, propyl, isopropyl, butyl, alkoxy groups such as methoxy, ethoxy, propoxy, phenoxy, nitro groups, cyano groups, dimethylamino, dibenzylamino, diphenylamino, morpholino , piperidino, pyrrolidino, and other substituted amino groups.

General formula 7・Y-1 H 1, Y-.

In the formula, Y represents a divalent aromatic hydrocarbon group or a heterocyclic divalent group containing a nitrogen atom in the ring, and the divalent aromatic hydrocarbon group includes a monocyclic aromatic group such as 0-phenylene. divalent group of group hydrocarbons, 0-naphthylene, perinaphthylene, 1
．． Divalent groups of aromatic hydrocarbons include fused polycyclic aromatics such as 2-antrylene and 9.10-phenanthrylene, and examples of divalent groups of heterocyclic rings containing a nitrogen atom in the ring include 3.4- Pyrazolediyl group, 2,3-pyridinediyl group, 4.5-pyrimidinediyl group, 6.7-indazolediyl group, 6,7
- Divalent groups such as a chiralediyl group can be mentioned.

In the general formula, RIO represents an aryl group or a heterocyclic group which may have a substituent, specifically phenyl, naphthyl, anthryl, pyrenyl, pyridyl, chenyl, furyl, carbazolyl group, and an aryl group. Examples of substituents for heterocyclic groups include halogen atoms such as fluorine, chlorine, iodine, and bromine; alkyl groups such as methyl, ethyl, propyl, isopropyl, and butyl; and alkoxy groups such as methoxy, ethoxy, propoxy, and phenoxy. group, nitro group, cyano group, dimethylamino, dibenzylamino, diphenylamino, morpholino.

Examples include substituted amine groups such as piperidino and pyrrolidino.

X has the same meaning as X in the general formula (2).

1.8゛.

In the formula, RLI and R12 represent an alkyl group, an aryl group, an aralkyl group, or a heterocyclic group which may have a substituent, specifically methyl, ethyl, propyl, butyl,
Benzyl, phenethyl, naphthylmethyl, phenyl, diphenyl, naphthyl, anthryl, carbazole, dibenzofuran, benzimidacilone, benzthiazole,
Thiazole and pyridine are shown, and substituents for alkyl groups, aryl groups, aralkyl groups, and heterocyclic groups include:
Halogen atoms such as fluorine, chlorine, iodine, and bromine atoms; alkyl groups such as methyl, ethyl, propyl, isopropyl, and butyl; alkoxy groups such as methoxy, ethoxy, propoxy, and phenoxy; nitro groups, cyano groups, and dimethylamino , dibenzylamino, diphenylamino, morpholino, piperidino, pyrrolidino, and other substituted amino groups.

X has the same meaning as X in the general formula (2).

Specifically, Arl and Ar2 in the general formula (1) include carbocyclic aromatic ring groups such as phenyl, naphthyl, and anthryl, or heterocyclic aromatic ring groups such as furyl, pyroyl, chenyl, pyridyl, and pyrazinyl. Substituents include halogen atoms such as fluorine, chlorine, iodine, and bromine; alkyl groups such as methyl, ethyl, propyl, impropyl, butyl; alkoxy groups such as methoxy, ethoxy, propoxy, and phenoxy; Examples include substituted amino groups such as cyano group, dimethylamino group, dibenzyl 7mino group, diphenylamino group, morpholino group, piperidino group, and pyrrolidino group.

Ar1. Examples of Ar2, Ar3, and Ar4 include carbocyclic aromatic ring groups such as phenyl, naphthyl, and anthryl, and heterocyclic aromatic ring groups such as furyl, pyroyl, chenyl, pyridyl, and pyrazinyl, and the substituent is a fluorine atom. , halogen atoms such as chlorine, iodine, and bromine atoms, alkyl groups such as methyl, ethyl, propyl, impropyl, butyl, alkoxy groups such as methoxy, ethoxy, propoxy, and phenoxy, nitro groups,
Examples include substituted amine groups such as cyano group, dimethylamino, dibenzylamino, diphenyl 7mino, morpholino, piperidino, and pyrrolidino.

Next, a general method for producing the disazo pigment used in the present invention will be explained.

When A and A' are the same in the disazo pigment represented by the general formula (1), the diamine represented by the following general formula (9) is converted into a tetrazonium salt by a conventional method such as sodium nitrite or nitrosyl sulfuric acid, and (in the formula , R, 7R5 and Ar
t'wAr4 has the same meaning as in general formula (1)), after performing aqueous coupling with the coupler components A and A', or extracting the obtained tetrazonium salt as a stable salt such as a borofluoride salt, It can be synthesized by coupling in an organic solvent such as DMF, and A
, A' are different, in the coupling reaction, first couple with the first coupler component to form a heptanoazo pigment, and then couple with the second coupler component to form a disazo pigment, or Although it can be synthesized by mixing the coupler components and subjecting them to a coupling reaction, the former method is preferred in order to ensure that an asymmetric pigment is obtained.

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) Exemplary pigment (4) Exemplary pigment (5) C,H.

C CoHr SuH Exemplary Pigment (8) SuH Exemplary Pigment (10) ○ Exemplary Pigment (11) SuH Exemplary Pigment (13) Exemplary Pigment (14) Exemplary Pigment (!5) Exemplary Pigment (17) Exemplary Pigment (18) ) Exemplary Pigment (20) Exemplary Pigment (22) Exemplary Pigment (23) Exemplary Pigment (24) Exemplary Pigment (2B) Exemplary Pigment (27) Exemplary Pigment (29) Exemplary Pigment (30) Exemplary Pigment (32) Exemplary Pigment (33 ) Exemplary Pigment (35) Exemplary Pigment (38) Exemplary Pigment (38) Exemplary Pigment (38) Exemplary Pigment (41) The disazo pigments shown in the above specific examples do not limit the scope of the claims of the present invention.

Coatings with the aforementioned disazo pigments exhibit photoconductivity and can therefore be used in photosensitive 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 support by vacuum evaporation, or by forming a film by dispersing it in a suitable binder. can do.

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 photosensitive layer is functionally separated into a charge generation layer and a charge transport layer.

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 photosensitive layer is functionally separated into a charge generation layer and a charge transport layer.

The charge generation layer contains as much of the above-mentioned photoconductive compound as possible in order to obtain sufficient light absorption, and the thin film layer 1 preferably has a thickness of, for example, 5 pm or less, in order to shorten the range of the generated charge carriers. is preferably a thin film layer having a thickness of 0.01-IJLm.

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 generating layer can be formed by dispersing the disazo pigment in a suitable binder and coating it on a substrate, or by forming a vapor deposited film using a vacuum vapor 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.),
Examples include insulating resins such as polycarbonate, polyester, phenoxy resin, polyvinyl acetate, acrylic resin, polyacrylamide, polyamide, polyvinylpyridine, cellulose resin, polyurethane, epoxy resin, casein, polyvinyl alcohol, and 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 soothing solvents include methanol, ethanol,
Alcohols such as isopropanol, 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 can be performed using a coating method such as a dip coating method or a spray coating method.

Drying is preferably carried out by drying to the touch at room temperature and then heating. Drying by heating can be carried out at a temperature of 30 to 200° C. for a period of from 5 minutes to 2 hours, either stationary or under ventilation.

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 the charge generation layer, or may be formed as an a layer below it.

When the charge transport layer is formed on the charge generation layer, charge transport materials include electron transport materials and hole transport materials.
Examples of electron-transporting substances include chloranil, bromoanil,
Tetracyanoethylene, Tetracyanokimedimethane, 2
, 4,7-dolinitro-9-fluorenone, 2,4,5
．． 7-tetranitro-9-fluorenone, 2,4.7-
) electron-withdrawing substances such as trinitro-9-dicyanomethylenefluorenone, 2゜4.5.7-titranitroxanthone, 2.4゜8-trinidrothioxanthone, and polymerized products of these electron-withdrawing substances, etc. There is.

Pyrene, N-ethylcarbazole, N-isopropylcarbazole, N-methyl-N-
7 Enylhydrazino 3-methylidene-9-ethylcarbazole, N,N-diphenylhydrazino-3-methylidene-9-ethylcarbazole, N,N-diphenyl 1radino 3-methylidene-10-ditylphenothiazine, N, N-diphenylhydrazino-3-methylidene-
10-Ethylphenoxazine, p-diethylaminobenzaldehyde-N, N-diphenylhydrazone, p-diethylaminobenzaldehyde-N-α-naphthyl-N
-Hydrazones such as phenylhydrazone, 2,5-bis(p-diethylaminophenyl)-1,3,4-oxadiazole, l-phenyl-3-(p-diethylaminostyryl)-5-(p-diethylaminophenyl) ) pyrazoline, 1-[quinolyl(2)]-2-(p-
diethylaminostyryl)-5-(p-diethylaminophenyl)pyrazoline, 1-[pyridyl(2)]-
3-(p-diethylaminostyryl)-5-(p-diethylaminophenyl)pyrazoline, 1-phenyl-3-
(p-diethylaminostyryl)-4-methyl-5-(
P-diethylaminophenyl) hirazoline, 1-phenyl-3-(α-benzyl-P-diethylami/styryl)-5-(p-diethylaminophenyl)pyrazoline,
Pyrazolines such as spiropyrazoline, 2-(p-diethylaminostyryl)-6-dinithylaminobenzoxazole, 2-(p-diethylaminophenyl)-4-
(p-dimethylaminophenyl)-5-(2-chlorophenyl)oxazole and other oxazole compounds,
Thiazole compounds 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, 1,1,2,2-tetrakis(4-N,
Polyarylalkanes such as N-dimethylamino-2-methylphenyl)ethane, triphenylamine, poly-N-vinylcarbazole, polyvinylpyrene, polyvinylanthracene, polyvinylacridine, poly-9-
Examples include vinylphenylanthracene, pyrene-formaldehyde resin, and ethylcarbazole-formaldehyde resin.

In addition to this organic charge transport material, selenium, selenium-tellurium,
Inorganic materials such as amorphous silicon and cadmium sulfide can also be used.

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

When the charge transport material does not have sufficient 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 has a limit in its ability to transport charge carriers, so it cannot be made thicker than necessary. Generally, the thickness is 5 to 30 pm, but the preferred range is 8 to 20 pm.
It is m. When forming a charge transport layer by coating,
Any suitable coating method, such as those 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. Examples of the substrate having a conductive layer include those whose substrate itself is conductive, such as aluminum, aluminum alloy, copper, zinc,
Stainless steel, vanadium, molybdenum, chromium, titanium, nickel.

Indium, gold, platinum, etc. are used.

In addition, plastics (e.g., polyethylene, polypropylene, polyvinyl chloride, polyethylene terephthalate, acrylic resin, polyfluoride, ethylene chloride, etc.), a substrate made of conductive particles (e.g. carbon black, silver particles, etc.) coated on plastic together with a suitable binder, a substrate made of plastic or paper impregnated with conductive particles, or a plus having a conductive polymer. ticks etc. can be used.

A subbing layer having barrier and adhesive functions can also be provided between the conductive layer 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 appropriate thickness of the undercoat layer is 0.1 to 5 ILm, preferably 0.5 to 3 ILm.

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 electrically 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 one surface, neutralize the positive charge, and attenuate by the same level as the one surface type, creating an electrostatic charge between the exposed area and the unexposed area. Contrast occurs.

A visible image is 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 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, then developed 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 transport material is a hole transport material, the surface of the charge transport layer must be negatively 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. After that, it reaches the surface and neutralizes the negative charge, resulting in attenuation of the surface potential and an electrostatic contrast between it and the unexposed area. During development, it is necessary to use a positively charged toner, contrary to when an electron transporting substance is used.

When using an electrophotographic photoreceptor in which a conductive layer, a charge transport layer, and a charge generation layer are laminated in this order, when the charge transport substance is an electron transport substance, the surface of the charge generation layer must be negatively charged; When exposed to light after charging, electrons generated in the charge generation layer are injected into the charge transport layer in the exposed area, and then reach the substrate. On the other hand, holes generated in the charge generation layer reach the surface, attenuation of the surface potential occurs, and electrostatic contrast occurs between the layer 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.

On the other hand, when the charge generation layer is made of a hole transport 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, electrons generated in the charge generation layer reach the surface, attenuation of the surface potential occurs, and electrostatic contrast occurs between the layer and the unexposed area. During development, it is necessary to use a negatively charged toner, contrary to the case where an electron transporting substance is used.

In addition, other specific examples of the present invention include the aforementioned hydrazones, pyrazolines, oxazoles, thiazoles, triarylmethanes, polyarylalkanes, triphenylamine, poly-N-vinylcarbazoles, etc. The photosensitive film may contain a disazo pigment represented by the general formula (1) as a sensitizer for a photoconductive substance or an inorganic photoconductive substance such as zinc oxide, cadmium sulfide, or selenium. This photosensitive film is formed by coating these photoconductive substances and the trisazo pigment together with a binder.

Furthermore, 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 formula along 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 aforementioned 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 pigment selected from disazo pigments represented by the general formula (1), and its crystal form may be amorphous or crystalline. good.

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% ammonia water, 1 g of ammonia water, 222 liters of water) was dried with a Mayer bar, and the film thickness was 1. It was coated to give Opm and dried.

Next, 5 g of the above-mentioned exemplary pigment (1) was added to ethanol 95 I
butyral resin (butyralization degree 63 mol%) 2
g was added to the dissolved liquid and dispersed in a sand mill for 2 hours.

The film thickness after drying of this dispersion on the previously formed casein layer is 0.5. Coat with a Mayer bar and dry to form a charge generation layer. 5g of hydrazone compound and 5g of polymethyl methacrylate (number average molecular weight 100,000) are mixed with benzene 70I! After drying, the solution was applied onto the charge generation layer to a film thickness of 12. The electrophotographic photoreceptor of Example 1 was prepared by coating with a Mayer bar and drying to form a charge transport layer.

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 statically charged with a corona at 15 KV using an electrostatic copying paper tester Model 5P-428 manufactured by Kawaguchi Denki ■, and after being held in a dark place for 1 second, an illumination intensity of 2 It was exposed to lux light and its charging characteristics were examined.

The charging characteristics include the surface potential (vO) and the exposure amount (El/
2) was measured. Show the results.

/ V -V El/2 1uxsec1
(1) 600 4.52 (2
) 650 2.23 (4) 60
0 2.64 (7) 610 2.
55 (8) 610 3.0
8 (10) 800 3.57
(12) 600 3.78
(14) 600 3.09
(1B) 610 3.410
(17) 590 3.411
(19) 600 3.512
(21) 610 2.813
(22) Boo 2.914
(23) 600 2.515
(24) 810 2.516
(2G) 590 3.017
(29) 600 2.718
(30) 600 3.219
(34) 610 2.420
(35) 590 3゛, 52
1 (37) 600 4.02
2 (38) 590 4.02
3 (39) 600 4.52
4 (40) Boo 3.0
25 (41) 610 3.
3 Furthermore, using the electrophotographic photoreceptor used in Example 2.8.21.22, fluctuations in bright area potential and dark area potential during repeated use were measured.

As a method, 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 (VL) and dark area potential (Vo) were set to around -100V and -600V, respectively, and the bright area potential (VL) after 5,000 uses.
and dark potential (VD) were measured.

The results are shown below.

2 600 Zoo 603 1058
600 Zoo 605 10321 Bo
o 100 601 10122 600
．． 100 802 105 Example 26 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 2. ) 5g was dissolved in 70tsl of tetrahydrofuran to prepare a coating solution.

It was applied and dried so that the coating amount after drying was 10 g/m2.

The electrostatic charge of the electrophotographic photoreceptor thus prepared was measured in the same manner as in Example 1. The charging polarity at this time was set to 10. Show the results.

Vo: +600V, El/2: 4.0Jlux, sec Example 27 The disazo pigment used in Example 2, in which a polyvinyl alcohol film with a thickness of 0.5 Bm was formed on the aluminum surface of an aluminum-deposited polyethylene terephthalate film. The dispersion was applied onto the previously formed polyvinyl alcohol layer using a Mayer bar so that the film thickness after drying was 0.51 zm, and dried to form a charge generation layer.

5 g of pyrazoline compound and 5 g of polyarylate (condensation polymer of bisphenol A and terephthalic acid-isophthalic acid)
A solution obtained by dissolving the above in 70 rsl of tetrahydrofuran was applied onto the charge generation layer so that the thickness after drying was 10% m, 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 Example 1. Show the results.

VONY 660V.

El/2: 2.3Rux, sec Initial durability characteristics Vo knee 600V, VL knee 100V After 5,000 sheets durability VD knee 605V, VL knee 108V As the above results show, the sensitivity is good and the potential stability during durable use is also good. It is.

Example 28 An ammonia aqueous solution of casein was coated on an aluminum plate with a thickness of 11007 zm and dried to form a subbing layer of 0.57 zm.

Next, 5 g of 2.4.7-dolinitro-9-fluorenone and poly-N-vinylcarbazole (number average molecular weight 300,000)
A charge transfer complex compound was prepared by dissolving 5 g in 70 m of tetrahydrofuran.

This charge transfer complex compound and 1 g of the above-mentioned exemplary pigment (50) were added to and dispersed in a solution in which 5 g of polyester was dissolved in 70% of tetrahydrofuran. This dispersion was applied onto the undercoat layer and dried to give a film thickness of 12 µm.

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

VO: +580V, El/2: 4.5 Jlux, sec Example 29 A charge transport layer and a charge generation layer similar to Example 20 were sequentially laminated on the casein layer of the aluminum base coated with the casein layer used in Example 28. A photoreceptor was prepared in the same manner except that the one-layer structure was different.

Charging characteristics were measured in the same manner as in Example 1.

However, the charging polarity was set to +.

vo: +600V, El/2: 4, OJluX, S
eC Example 30 The photoreceptor used in Example 13 [Example Pigment (22)] was
When exposed to light using a semiconductor laser with an oscillation wavelength of 80 nm, the spectral sensitivity at 780 nm was 2.3 pJ/
When this photoreceptor was formed on the drum of a Canon LBP-CX and an actual photographic test was conducted, good images without fogging were obtained. This did not change even after repeating this 10,000 times.

Examples 31 to 34 A drum-shaped photoreceptor was prepared in the same manner except that the disazo pigments exemplified by pigments (19), (26), (39), and (41) were used in place of the disazo pigment used in Example 30. Created.

The spectral sensitivity of each photoreceptor at 780 nm was as follows.

S J/cm 2 31 (+9) 2.2 32 (2B) 2.1 33 (39) 2.0 34 (41) 2.0 Next, when a live photo test was conducted in the same manner as in Example 30, fogging was detected. An image free of blemishes was obtained, and this did not change even after repeating 10,000 times.

[Effects of the Invention] By using a specific disazo pigment in the photosensitive layer, the electrophotographic photoreceptor of the present invention improves either or both carrier generation efficiency and carrier transport efficiency within the photosensitive layer containing the disazo pigment. It is estimated to improve the image quality, has high sensitivity and excellent potential stability during long-term use, and has the remarkable effect of being able to obtain good images without fog with high sensitivity even in the oscillation wavelength range of semiconductor lasers. play.

Claims (8)

[Claims] (1) An electrophotographic photoreceptor having a photoconductive layer, characterized in that the photoconductive layer contains a disazo pigment represented by the following general formula (1). General formula (1) ▲There are numerical formulas, chemical formulas, tables, etc.▼ In the formula, R_1 is a hydrogen atom, an alkyl group that may have a substituent, an aryl group, an aralkyl group, an alkoxy group, a halogen atom, a nitro group, a cyano group, etc. Indicates a group, R_2,
R_3, R_4 and R_5 represent a hydrogen atom or an electron-withdrawing group, A and A' represent a coupler residue having a phenolic hydroxyl group, A and A' may be the same or different, Ar_1, Ar_2, A_3 and Ar_4 represent a substituted or unsubstituted carbocyclic aromatic ring group or a substituted or unsubstituted heterocyclic aromatic ring group, and Ar_1, Ar_2, A_3 and A_4 are the same or different. It's okay. (2) The electrophotographic photosensitive material according to claim 1, wherein one or both of A and A' in the general formula (1) is a coupler residue having a phenolic hydroxyl group represented by the following general formula (2). body. General formula▲There are mathematical formulas, chemical formulas, tables, etc.▼(2) In the formula, It represents a cyclic amino group together with an alkyl group, an aryl group, an aralkyl group, a heterocyclic group, or the nitrogen atom to which R_6 and R_7 are bonded, which may have a group. (3) The electrophotographic photosensitive material according to claim 1, wherein one or both of A and A' in the general formula (1) is a coupler residue having a phenolic hydroxyl group represented by the following general formula (3). body. General formula ▲ Numerical formula, chemical formula, table, etc. ▼ (3) In the formula, R_8 represents an alkyl group, an aryl group, or an aralkyl group that may have a substituent. (4) Electrophotographic sensitization according to claim 1, wherein one or both of A and A' in general formula (1) is a coupler residue having a phenolic hydroxyl group represented by the following general formula (4). body. General formula ▲There are numerical formulas, chemical formulas, tables, etc.▼ (4) In the formula, R_9 represents an alkyl group, an aryl group, or an aralkyl group that may have a substituent. (5) The electrophotographic photosensitive material according to claim 1, wherein one or both of A and A' in the general formula (1) is a coupler residue having a phenolic hydroxyl group represented by the following general formula (5). body. General formula ▲ Numerical formula, chemical formula, table, etc. ▼ (5) In the formula, Y represents a divalent aromatic hydrocarbon group or a heterocyclic divalent group containing a nitrogen atom in the ring. (6) Electrophotographic sensitization according to claim 1, wherein one or both of A and A' in general formula (1) is a coupler residue having a phenolic hydroxyl group represented by the following general formula (6). body. General formula ▲ Numerical formula, chemical formula, table, etc. ▼ (6) In the formula, Y represents a divalent aromatic hydrocarbon group or a heterocyclic divalent group containing a nitrogen atom in the ring. (7) The electrophotographic photosensitive material according to claim 1, wherein one or both of A and A' in the general formula (1) is a coupler residue having a phenolic hydroxyl group represented by the following general formula (7). body. General formula ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (7) In the formula, R_1_0 represents an aryl group or a heterocyclic group that may have a substituent, and X has the same meaning as X in the general formula (2) above. It is. (8) The electrophotographic photosensitive material according to claim 1, wherein one or both of A and A' in the general formula (1) is a coupler residue having a phenolic hydroxyl group represented by the following general formula (8). body. General formula ▲There are numerical formulas, chemical formulas, tables, etc.▼ (8) In the formula, R_1_1 and R_1_2 represent an alkyl group, an aryl group, an aralkyl group, or a heterocyclic group that may have a substituent, and X is the general formula shown above. It has the same meaning as X in (2).