JPS63163364A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To enhance sensitivity and potential stability during uses for a long time by using a specified disazo pigment for a photosensitive layer. CONSTITUTION:The electrophotographic sensitive body is provided with a photoconductive layer containing one of the disazo pigments represented by formula I in which each of R1-R4 is H atom or an electron attractive group; each of R5 and R6 is H atom or optionally substituted alkyl, aralkyl, or aryl group, or a group for forming an optionally substituted hydrocarbon cyclic group or aromatic hydrocarbon ring group or heterocyclic aromatic group; each of A and A' is a coupler residue having a phenolic hydroxyl group; each of Ar1-Ar4 is an optionally substituted aromatic hydrocarbon ring group or such a heterocyclic aromatic group, thus permitting the obtained photosensitive body to obtain practicable high sensitivity characteristics and stable potential characteristics against repeated uses.

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. 38
It is described in Publication No. 16118 and the like. In addition, examples of organic semiconductors used in electrophotographic photoreceptors include US Pat. No. 4,315,983 and US Pat. No. 4,32716.
Publication No. 9 and “Re+each Disclosure” 2
0517 (1981, 5), methine squaric acid dyes described in U.S. Pat. No. 3,824,099, U.S. Pat. No. 389
Examples include disazo pigments described in JP-A No. 8084, US Pat. No. 4,251,613, 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.

[Problem to be Solved by the Invention J 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 durable in repeated use. An object of the present invention is to provide an electrophotographic photoreceptor having stable potential characteristics.

Means for Solving Problem E, Effect 1 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) In the formula, R,, R2, R3 and R4 represent a hydrogen atom or an electron-withdrawing group, and R5 and R6 represent a hydrogen atom or an alkyl group which may have a substituent, a 7-ralkyl group or an aryl group. represents a group, or represents a group forming a substituted or unsubstituted cyclic hydrocarbon group, carbocyclic aromatic ring group, or heterocyclic aromatic ring group with R5 and Re, and A and Ao have a phenolic hydroxyl group. Indicates a coupler residue, A and A' may be the same or different,
Ar1, Ar2, Ar3 and Ar4 represent a substituted or unsubstituted carbocyclic aromatic ring group or a heterocyclic aromatic ring group, and Ar1. Ar2.

Ar3. Ar4 may be the same or different.

Specifically, examples of the electron-withdrawing group in R1 to R4 include halogen atoms such as a glossy atom, a chlorine atom, a bromine atom, and an iodine atom, a cyano group, and a nitro group.

R5 and R6 are methyl, ethyl, propyl.

Examples include groups such as isopropyl, butyl, S-butyl, t-butyl, phenyl, P-tolyl, benzyl, and further substituents include fluorine atom, chlorine atom, bromine atom,
: Halogen atoms such as atomic atoms, alkyl groups such as methyl, ethyl, propyl, butyl, alkoxy groups such as methoxy, ethoxy, propoxy, phenoxy, nitro group, cyano group, dimethylamino, diethylamino, dibenzylamino, diphenyl Examples include substituted amino groups such as amine/morpholino, piperidino, and pyrrolidino.

More preferable specific examples of coupler residues having a phenolic hydroxyl group A and Ao include the following general formulas (2) to (8).
) are included.

In the general formula, x is fused 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.

R7 and R8 are hydrogen atoms, alkyl groups that may have substituents, aryl, aralkyl groups, heterocyclic groups, or R
7, represents a cyclic amino group together with the nitrogen atom to which R8 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 and dibenzofuran.

Examples include thiazole and pyridine.

In the general formula R, Rs and Rlo represent a hydrogen atom, an alkyl group that may have a substituent, an aryl group, or a 7-ralkyl group. Specific examples of Rs and RIO are shown by the same examples as R7 and Rr above. .

Alkyl groups, aryl groups, aralkyl groups, alkoxy groups represented by substituents R7 to Rto in general formulas (2) to (4),
The heterocyclic group may further include other substituents such as fluorine atom, chlorine atom, iodine atom, bromine atom, tonohalogen atom, alkyl group such as methyl, ethyl, propyl, impropyl, butyl, methoxy, ethoxy, propoxy, phenoxy, etc. It may be substituted with a substituted amino group such as an alkoxy group, a nitro group, a cyano group, dimethylamino, dibenzylamino, diphenylamino, morpholino, piperidino, or pyrrolidino.

υH , -Y-, where Y represents a divalent aromatic hydrocarbon group or a heterocyclic divalent group containing a nitrogen atom in the ring, and the aromatic hydrocarbon divalent group is 0. - Divalent groups of monocyclic aromatic hydrocarbons such as phenylene, 0-naphthylene, perinaphthylene, l
, 2-antrylene, 9.10-phenanthrylene, and other fused polycyclic aromatic hydrocarbon groups, and examples of heterocyclic divalent groups containing a nitrogen atom in the ring include 3,4
-Pyrazolediyl group, 2,3-pyridinediyl group, 4
．． Divalent groups such as 5-pyrimidinediyl group, 6,7-indazolediyl group, and 6,7-chiralindiyl group can be mentioned.

In the general formula, R11 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 atoms, +jX atoms, iodine atoms, and bromine atoms; alkyl groups such as methyl, ethyl, propyl, isopropyl, and butyl; Examples include substituted amino groups such as an alkoxy group, a nitro group, a cyano group, dimethylamino, dibenzylamino, diphenylami/1morpholino, piperidino, and pyrrolidino.

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

In the formula, R12 and R13 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; alkyl groups such as methyl, ethyl, propyl, isopropyl and butyl; alkoxy groups such as methoxy, ethoxy, propoxy and phenoxy; nitro group, cyan group and dimethylamino , dibenzylamino, diphenylamino, morpholino, piperidino, pyrrolidino, and other substituted amino groups.

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

c7) Ar1. in general formula (1). Specifically, Ar2, Ar3 and Ar4 are carbocyclic aromatic ring groups such as phenyl, naphthyl, and anthryl, or heterocyclic aromatic ring groups such as furyl, pyroyl, chenyl, pyridyl, and pyrazinyl, and as substituents, are fluorine atoms, chlorine atoms,
Halogen atoms such as 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, dimethylamino, dibenzylamino, and diphenyl. amino, morpholino,
Examples include substituted amino groups such as piperidino and pyrrolidino.

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

When A and Ao 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 using a conventional method such as sodium nitrite or nitrosyl sulfuric acid.

Synthesis is carried out by performing aqueous coupling with the coupler components A and A', or by extracting the obtained tetrazonium salt as a stable salt such as a borofluoride salt and then coupling in an organic solvent such as DMF. Yes, A
, A' are different, in the coupling reaction, first couple with the first coupler component to form a heptanoazo compound.

It can be synthesized by coupling with a second coupler component to produce a disazo pigment, or by mixing two coupler components and subjecting them to a coupling reaction, but in order to reliably obtain an asymmetric pigment, it is necessary to use the former method. The method is preferred.

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

Exemplary Pigment (1) Exemplary Pigment (2) Exemplary Pigment (3) Exemplary Pigment (0 Exemplary Pigment (5) Exemplary Pigment (lO) Exemplary Pigment (11) Exemplary Pigment (16) Exemplary Pigment (20) Exemplary Pigment (21) Exemplary Pigment Pigment (23) Exemplary Pigment (24) Exemplary Pigment (28) Exemplary Pigment (27) Exemplary Pigment (28) Exemplary Pigment (30) Exemplary Pigment (32) Exemplary Pigment (33) Exemplary Pigment (35) Exemplary Pigment (36) Exemplary Pigment Pigment (38) Exemplary Pigment (39) Exemplary Pigment (40) Exemplary Pigment (41) Exemplary Pigment (44) Exemplary Pigment (45) Exemplary Pigment (47) Exemplary Pigment (48) Exemplary Pigment (50) Exemplary Pigment (51) Above The disazo pigments shown in the specific examples are not intended to 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 dispersing it in a suitable binder and forming a film. 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 is preferably a thin film layer, for example, 5 JLm 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 to lpm.

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 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, polyvinyl 7-tothecene, 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 organic 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 7-methyl ether;
Esters such as methyl acetate and ethyl acetate, aliphatic halogenated hydrocarbons such as chloroform, methylene chloride, dichloroethylene, carbon tetrachloride, and trichloroethylene, or benzene and toluene.

Aromatic hydrocarbons such as xylene, ligroin, monochlorobenzene, dichlorobenzene, etc. 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 done by drying to the touch at room temperature and then keeping it dry by heating.Heat drying 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 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, tetracyanoquinodimethane, 2
, 4,7-dolinitro-9-fluorenone, 2,4,5
．． 7-tetranitro-9-fluorenone, 2,4.7-
)! J Nitro 9-dicyanomethylene fluorenone, 2
゜4.5.7-Titranitroxanthone, 2,4゜8-
Examples include electron-withdrawing substances such as trinidrothioxanthone and polymerized versions of these electron-withdrawing substances.

Examples of hole-transporting substances include pyrene, N-ethylcarbazole, N-inpropylcarbazole, 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
-Hydrazones such as phenylhydrazone, P-pyrrolidinobenzaldehyde N, N-diphenylhydrazone, 2.5-bis(p-diethylaminophenyl)-1,
3,4-oxadiazole, l-phenyl-5-(p-
diethylaminostyryl)-5-(p-diethylaminophenyl)pyrazoline, 1-[quinolyl(2)]-2-
(p-diethylaminostyryl)-5-(p-diethylaminophenyl)pyrazoline, 1-[pyridyl (2)]
-5-(p-diethylaminostyryl)-5-(p-diethylaminophenyl)pyrazoline, l-phenyl-5
-(p-diethylaminostyryl)-4-methyl-3-
Pyrapurines such as (p-diethylaminophenyl)pyrazoline, 1-phenyl-5-(α-benzyl-p-diethylaminostyryl)-5-(p-diethylaminophenyl)pyrazoline, and 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, methane compounds such as bis(4-diethylamino-2-methylphenyl)-phenylmethane, 1.1- Bis(4-N,N-diethylamino-2-methylphenyl)hebutane, 1,1,2,2-tetrakis(
Polyarylalkanes such as 4-N,N-dimethylamino-2-methylphenyl)ethane, triphenylamine, poly-N-vinylcarbazole, polyvinylpyrene, polyvinyl 7-thracene, polyvinyl acridine, poly-9-vinylphenylanthracene , pyrene-formaldehyde resin, ethylcarbazole-formaldehyde resin, etc.

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 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. What resins can be used as binders?

For example, acrylic resin, polyarylate, polyester,
Polycarbonate, polystyrene, acrylonitrile
Styrene copolymer, acrylonitrile-butadiene copolymer, polyvinyl butyral, polyvinyl formal, polysulfone, polyacrylamide, polyamide,
Examples include insulating resins such as 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,
Using a suitable coating method as described above is recommended.
Wear.

A photosensitive layer having such an a-layer 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, and platinum are used.

In addition, plastics (e.g., polyethylene, polypropylene, polyvinyl chloride, polyethylene terephthalate, acrylic resin, polyfluoride, ethylene chloride, etc.), conductive particles (e.g. carbon black, silver particles, etc.) coated on plastic with a suitable binder, conductive particles impregnated into plastic or paper, and plastics containing conductive polymers. Can be used.

A subbing layer having barrier and adhesive functions can also be provided between the conductive layer and the photosensitive layer. The undercoat layer is formed from casein, polyvinyl alcohol, nitrocellulose, ethylene-acrylic acid copolymer, polyamide (nylon 6, nylon 66, nylon 610, copolymerized nylon, flukoxymethylated nylon, etc.), polyurethane, gelatin, aluminum oxide, etc. can. The appropriate thickness of the undercoat layer is 0.1 to 5 pm, 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 the surface and neutralize the positive charge, resulting in an attenuation of about 1 surface type, and static electricity is created between the exposed area and the unexposed area. Electrocontrast 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.

On the other hand, when the charge transport material is made of 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, causing an attenuation of about one surface type and creating an electrostatic contrast with 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 and are attenuated by one surface type, creating an electrostatic contrast with 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, 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 generation layer is made of a hole transport material, the surface of the charge generation layer must be positively charged, and when exposed after being charged,
In the exposed area, holes generated in the charge generation layer are injected into the charge transport layer and then reach 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.

Further, in another specific example of the present invention, organic photoconductive substances such as the aforementioned hydrazones, pyrazolines, oxazoles, thiazoles, triarylmethanes, polyarylalkanes, triphenylamine, and poly-N-vinylcarbazoles are used. and zinc oxide.

A photosensitive film containing a disazo pigment represented by the above general formula (1) as a sensitizer for inorganic photoconductive substances such as cadmium sulfide and selenium can be provided. This photosensitive film is formed by coating these photoconductive substances and the trisazo pigment together with a binder. Further, as another specific example of the present invention, there may be mentioned an electrophotographic photoreceptor in which a disazo pigment represented by the above-mentioned general formula (1) is contained 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 in this example is the above-mentioned disazo type.

It can be prepared by dispersing the charge transfer complex compound and the charge transfer complex compound in a polyester solution dissolved in tetrahydrofuran, and then forming a film.

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, and 22 ml of water) was applied using a Meyer bar so that the film thickness after drying was 1.0 μm, and then dried.

Next, 5 g of the exemplary pigment (1) was added to ethanol 95+J
2 g of butyral resin (degree of butyralization 63 mol%) for L
was added to the dissolved solution and dispersed in a sand mill for 2 hours. This dispersion was applied onto the previously formed casein layer using a Mayer bar so that the film thickness after drying was 0.5 gm, and dried to form a charge generating layer containing 5 g of a hydrazone compound and polymethyl methacrylate (number average molecular weight 100,000) 5g to benzene 7
The electrophotographic photoreceptor of Example 1 was prepared by dissolving the solution in 0.0 m and applying it onto the charge generation layer using a Mayer bar so that the film thickness after drying was 12 pm, and drying to form a charge transport layer. did. Electrophotographic photoreceptors corresponding to Examples 2 to 25 were prepared in exactly the same manner using other exemplary pigments in place of exemplary pigment (1).

The electrophotographic photoreceptor thus produced was statically tested using an electrostatic copying paper tester (SP-428).
After corona charging with KV and holding for 1 second in the dark, the illumination intensity was 2.
It was exposed to lux light and its charging characteristics were investigated.

The charging characteristics include the surface potential (Vo) and the amount of light exposure (El) required to attenuate the potential to 1/2 when the dark decay occurs for 1 second.
/2) was measured. Show the results.

t ・V −V El/2 1uxsec1
(1) 600 3.02 (2)
650 2.33 (4) 600
2.44 (7) 610 2.55
(8) slo 3. Os (
io)6oo 3.57 (12) 6
00 3.78 (14) 600 j
, 09 (1B) 610 3.410
(17) 590 3.411 (
18) 600 3.012 (21)
610 2.813 (22)
600 2.914 (23)
600 2.515 (24)
610 2.516 (2B)
590 3.017 (27)
sho 2.718 (30)
600 3.219 (38)
610 2.020 (37)
590 3.521 (40)
600 3.822 (41)
590 3.523 (44)
800 4.024 (45)
600 3.025 (50)
610 3.3 Furthermore, Example 2.8.9
．． Using the electrophotographic photoreceptor used in 12.13, 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 constructed so that an image can be obtained on transfer paper as the shilling is driven.

Using this copier, the initial bright area potential (VL) and dark area potential (Vo) were set to around fl-100V and -6O0v, and the bright area potential (VL) after 5,000 uses was set.
) and dark potential (Vo) were measured.

The results are shown below.

12 600 Zoo 612 108 Example 26 5 g of 2.4° 7-dolinitro-9-fluorenone and poly-4,4-dioxydiphenyl-2,2-propane carbonate (molecular weight 300,000) 5g was dissolved in 70rrrl of tetrahydrofuran to make a coating solution, and the coating amount after drying was 10g/m.
2 and dried.

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.

VQ: +600V, El/2: 3.8fLux, secExample 27 A film of polyvinyl alcohol with a thickness of 0.5gm was formed on the aluminum surface of an aluminum vapor-deposited polyethylene terephthalate film.Disazo pigment used in Example 2 The dispersion was applied onto the previously formed polyvinyl alcohol layer using a Mayer bar so that the film thickness after drying was 0.5 gm, 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-inphthalic acid)
A solution obtained by dissolving the above in 70 ml of tetrahydrofuran was applied onto the charge generation layer so that the thickness after drying was 10 pm, 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.

vow-645V, E 1/2: 2, 5 views u X, S e
c Durability characteristics initial V D: -600V, V L: -1
00V after 5,000 sheets of durability VD knee 603V, VL knee 103V As shown in the above results, the sensitivity is good and the potential stability during durable use is also good.

Example 28 An ammonia aqueous solution of casein was coated on an aluminum plate with a thickness of 100 gm and dried to form a subbing layer of 0.5 gm.

Next, 5 g of 2.4.7-dolinitro-9-fluorenone and poly-N-vinylcarbazole (number average molecular weight 300,000)
5g of tetrahydrofuran 701! Further, a charge transfer complex compound was prepared by dissolving it.

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 volumes of tetrahydrofuran. This dispersion was applied onto the undercoat layer and dried to give a film thickness of 12 ILm.

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: 3.91uX, 5eC Example 29 The same charge transport layer and charge generation layer as in Example 13 were sequentially laminated on the casein layer of the aluminum base coated with the casein layer used in Example 28, and the layer structure was A photoreceptor was prepared in the same manner except for the following differences.

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

However, the charging polarity was set to 10.

VO: +610V, El/2: 3.51ux, sec Example 30 The photoreceptor used in Example 25 [Example Pigment (50)] was
When exposed to light using a semiconductor laser with an oscillation wavelength of 80 nm, the spectral sensitivity at 780 nm was 2.07 tJ.
/cm2 (half exposure amount).

Next, this photoreceptor was printed using a laser beam printer (LBP).
-CX) and a live-photography test was conducted, and a good image without fogging was obtained. Also, this did not change even after turning the tree over 10,000 times.

Examples 31 to 34 A drum-shaped photoreceptor was prepared in the same manner as in Example 30, except that the disazo pigments exemplified by pigments (37), (41), (45), and (52) 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.

6' -% J/C, 2
31 (37) 1.2 32 (41) 1.333
(45) 2.034 (
52) 2.5 Next, a live photographing test was conducted in the same manner as in Example 30, and a fog-free image was obtained, which 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 that it will improve the image quality, and is highly sensitive and has excellent potential stability during long-term use.It also has the remarkable effect of being able to obtain good images without capri 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 mathematical formulas, chemical formulas, tables, etc.▼ In the formula, R_1, R_2, R_3 and R_4 represent hydrogen atoms or electron-withdrawing groups, and R_5 and R_6 may have hydrogen atoms or substituents. Indicates a good alkyl group, aralkyl group or aryl group, or R_5,
R_6 represents a group forming a substituted or unsubstituted cyclic hydrocarbon group, carbocyclic aromatic ring group or heterocyclic aromatic ring 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, Ar_3 and Ar_4 represent substituted or unsubstituted carbocyclic aromatic ring groups or heterocyclic aromatic ring groups; Ar_1, Ar_2
, Ar_3, and Ar_4 may be the same or different. (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_7 and R_8 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_3 represents an alkyl group, an aryl group, or an aralkyl group that may have a substituent. (4) 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 (4). body. General formula ▲ Numerical formula, chemical formula, table, etc. ▼ (4) In the formula, R_1_0 is an alkyl group that may have a substituent,
Indicates an aryl group or an aralkyl group. (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) 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 (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) 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 (7). body. General formula ▲ Numerical formula, chemical formula, table, etc. ▼ (7) In the formula, R_1_1 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 mathematical formulas, chemical formulas, tables, etc.▼(8) In the formula, R_1_2 and R_1_3 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).