JPH01180555A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To enhance carrier generating and transfer efficiencies in a photoconductive layer and to ameliorate sensitivity and potential stability at the time of repeated use by incorporating a specified disazo pigment in the photosensitive layer. CONSTITUTION:The electrophotographic sensitive body is obtained by forming on a conductive substrate the photosensitive layer containing at least one of the disazo pigments represented by formula I in which each of Ar1 and Ar2 is an aromatic hydrocarbon ring or hetero ring; each of Cp1 and Cp2 is a coupler residue having a phenolic OH group, optionally same or different from each other; Z is O or S; and n is 1 or 2, thus permitting the obtained electrophotographic sensitive body to have high sensitivity characteristics and potential stability characteristics at the time of repeated use.

Description

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

[Prior Art] Conventionally, as electrophotographic photoreceptors using inorganic photoconductive substances, those using selenium, cadmium sulfide, zinc oxide, etc. are widely known.

On the other hand, electrophotographic photoreceptors using organic photoconductive substances include photoconductive polymers typified by poly-N-vinylcarbazole and 2,5-bis(p-diethylaminophenyl)-1,3,4- Those using a low-molecular organic photoconductive substance such as oxadiazole, and those using a combination of such an organic photoconductive substance and various dyes and pigments are known.

Electrophotographic photoreceptors using organic photoconductive substances have good film forming properties, can be produced by coating, and have extremely high productivity.
It has the advantage of being able to provide an inexpensive photoreceptor. In addition, it has the advantage that color sensitivity can be freely controlled by selecting the sensitizers used, such as dyes and pigments, and has been extensively studied. Particularly recently, with the development of a functionally separated photoreceptor, which has an organic photoconductive pigment as a charge generation layer and a charge transport layer made of the aforementioned photoconductive polymer or low-molecular organic conductive substance, Significant improvements have been made in the sensitivity and durability, which were considered to be drawbacks of electrophotographic photoreceptors, and they are now being put into practical use.

However, they are still inferior to inorganic electrophotographic photoreceptors in terms of sensitivity and potential stability during repeated use, and further improvements are desired.

[Issue 8 to be solved by the invention] An object of the present invention is to provide a novel photoconductive material;
It is an object of the present invention to provide an electrophotographic photoreceptor having practical high-sensitivity characteristics and stable potential characteristics when used for edge reversing.

[Means for Solving the Problems, Effects] The present invention comprises an electrophotographic photoreceptor characterized by having a photosensitive layer containing a disazo pigment represented by the following general formula (1) on a conductive support. .

General formula % Formula % (1) In the formula, Ar1 and Ar2 represent an aromatic hydrocarbon ring or a heterocycle which may have a substituent, specifically an aromatic hydrocarbon ring such as a benzene ring, a naphthalene ring, an anthracene ring, etc. Examples include heterocycles such as hydrocarbon rings, pyridine rings, carbazole rings, and quinoline rings.

Substituents on these aromatic hydrocarbon rings and heterocycles include hydrogen atoms, halogen atoms such as fluorine atoms, chlorine atoms, and bromine atoms, alkyl groups such as methyl, ethyl, and propyl, aralkyl groups such as benzyl and phenethyl, methoxy, Examples include alkoxy groups such as ethoxy, cyano groups, and nitro groups.

CPI and CF2 are the same or different and represent a coupler residue having a phenolic hydroxyl group, Z represents an oxygen atom or a sulfur atom, and n is an integer of 1 or 2.

Specifically, preferred specific examples of coupler residues having a phenolic hydroxyl group represented by cpt and CF2 include residues represented by the following general formulas (2) to (6).

'XP In the formula, Residues necessary to form an aromatic ring or a heterocycle 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.

R1 and R2 are a hydrogen atom, an alkyl group which may have a substituent, an aryl, an aralkyl group, a heterocyclic group or 1
A cyclic amino group containing a nitrogen atom to which R, , R2 is bonded in the ring.

Specifically, alkyl groups include methyl, ethyl, propyl, and butyl, aralkyl groups include benzyl, phenethyl, and naphthylmethyl, and aryl groups include phenyl, diphenyl, naphthyl, anthryl, and hetero groups. Examples of the ring group include cal-A)-l, dibenzofuran, benzimidacilone, benzthiazole, and thiazole.

Examples include groups such as pyridine.

Z represents an oxygen atom or a sulfur atom.

n represents an integer of O or 1.

General Formula R3 In the formula, R3 represents a hydrogen atom, an alkyl group that may have a substituent, an aryl group, or an aralkyl group. Specific examples of R3 are shown by the same examples as R, and R2 described above.

Furthermore, substituents for the alkyl group, aryl group, aralkyl group, and heterocyclic group represented by substituents R1 to R3 in general formulas (2) and (3) include, for example, a fluorine atom, a chlorine atom, an iodine atom, and a bromine atom. Halogen atoms such as methyl, ethyl, propyl, isopropyl, alkyl groups such as butyl, alkoxy groups such as methoxy, ethoxy, propoxy, phenoxy, nitro groups, cyan groups, dimethylamino,
Examples include substituted amino groups such as dibenzylamino, diphenylamino, morpholino, piperidino, and pyrrolidino.

In the formula, Y represents a divalent aromatic hydrocarbon group or a heterocyclic divalent group containing a nitrogen atom in the ring, and examples of the aromatic hydrocarbon divalent group include monocyclic groups such as 0-phenylene. Divalent group of aromatic hydrocarbons, 0-naphthylene, perinaphthylene,
Examples include divalent groups of fused polycyclic aromatic hydrocarbons such as 1, 2-antrylene and 9,10-phenanthrylene, and examples of divalent groups of heterocycles containing a nitrogen atom in the ring include 3゜4- pyrazolediyl group, 2,3-pyridinediyl group,
Divalent groups such as 4.5-pyrimidinediyl group, 6.7-indazolediyl group, and 6.7-chimerindiyl group are mentioned.

In the general formula, R4 represents an aryl group or a heterocyclic group which may have a substituent; specifically, the aryl group is phenyl, naphthyl, anthryl, pyrenyl, etc., and the heterocyclic group is pyridyl. , thienyl, furyl, carbazolyl, etc.

Further, as substituents for aryl groups and heterocyclic groups, halogen atoms such as fluorine atom, chlorine atom, iodine atom, and bromine atom, alkyl groups such as methyl, ethyl, propyl, inpropyl, and butyl, methoxy, ethoxy, propoxy, Examples include alkoxy groups such as phenoxy, nitro groups, cyano groups, dimethylamino, dibenzylamino, diphenylamino, morpholino, piperidino, pyrrolidino and other substituted amide groups.

X has the same meaning as X in -Sailor (2) above.

ゝX' In the formula, R5 and R6 represent an alkyl group, an aralkyl group, an aryl group, or a heterocyclic group which may have a substituent, and specifically, the alkyl group includes methyl, ethyl, propyl, butyl. Examples of aralkyl groups include benzyl, phenethyl, and naphthylmethyl; aryl groups include phenyl, diphenyl, naphthyl, and anthryl; and heterocyclic groups include carbazolyl, thienyl, pyridyl, and furyl. Furthermore, as substituents for alkyl groups, aralkyl groups, aryl groups, and heterocyclic groups, halogen atoms such as fluorine atoms, chlorine atoms, iodine atoms, and bromine atoms, methyl, ethyl, propyl,
Alkyl groups such as isopropyl and butyl; alkoxy groups such as methoxy, ethoxy, propoxy, and phenoxy;
Examples include substituted amine groups such as nitro group, cyano group, dimethylamino, dibenzylamino, diphenylamino, morpholino, piperidino, and pyrrolidino.

X has the same meaning as X in -Sailor (2) above.

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) Cpl-N-N+C0NH-@-N-N-cP YuQ Exemplary pigment (3) Cp□-N -N -@)-CON H(■N -N
-Cp Exemplary Pigment (4) Exemplary 1m Size (5) Exemplary Pigment (6) Exemplary Pigment (7) ap 1-N-N@-cONH-@-NmN-Cp Yu Exemplary Pigment (8) Cp, -N- N-@-CONH-@-N-N-C;p
.

Exemplary pigment (9) Cp 1-N-N-@-captH-os-N-cp
z Exemplary Pigment (10) Exemplary Pigment (11) Exemplary Pigment (12) Exemplary Pigment (13) Op, -N-N+cONH+N Small cp Yu Exemplary Pigment (14
) Cp, -N-N-o-CONH+N-N-0p2 Exemplified Pigment (15) Exemplified Pigment (16) cp, -N-NICON)! eN-N-CPzW Exemplary Pigment (17) Exemplary Pigment (18) Exemplary Pigment (19) Exemplary Pigment (20) Exemplary Pigment (21) Exemplary Pigment (22) Exemplary Pigment (23) Exemplary Pigment (24) Exemplary Pigment (25) Exemplary Pigment (26) Exemplary Pigment (27) Exemplary Pigment (28) Exemplary Pigment (29) Exemplary Pigment (30) Exemplary Pigment (31) Exemplary Pigment (32) Exemplary Pigment (33) Exemplary Pigment (34) Exemplary Pigment (35) Exemplary Pigment (36) Exemplary Pigment (37) Exemplary Pigment (38) Exemplary Pigment (39) The disazo pigment represented by the general formula (1) is not limited to the above-mentioned disazo pigment.

The disazo pigment represented by the general formula (1) is obtained by tetrazotizing the corresponding diamine by a conventional method and coupling it with the corresponding coupler in the presence of an alkali, or by converting the tetrazonium salt into a borofluoride salt or zinc chloride double salt, etc. ,N,
It can be easily synthesized by coupling with a corresponding coupler in a solvent such as N-dimethylamide or dimethyl sulfoxide in the presence of a base such as sodium acetate, pyridine, triethylamine, or triethanolamine.

If CPl and CR2 are different, synthesize by first coupling the above-mentioned tetrazonium salt with the first coupler and then coupling with the second coupler, or protect the 7-mino group of one of the diamines with an acetyl group, etc. This is then diazotized, coupled with the first coupler, hydrolyzed with hydrochloric acid or the like to protect the acetyl group, diazotized again, and synthesized by coupling with the second coupler. Can be done.

Synthesis example (synthesis of exemplified pigment (1)) In a 300ml beaker, add 150ml of water and 20ml of concentrated hydrochloric acid.
Sentence (0,23%) and H YuNshaC0N)IshaN)lE 7゜3g (0,0
32 mol), cooled to 0°C, and added a solution of 4.6 g (0,067 mol) of sodium nitrite dissolved in water for 10 minutes while controlling the liquid temperature to below 5°C. After the dropwise addition was completed, the mixture was stirred for 15 minutes, carbon was added, and the mixture was filtered. A solution prepared by dissolving 10.6 g (0,096 mol) of sodium borofluoride in 40 ml of water was added dropwise to the obtained tetrazotized solution, and the precipitated borofluoride salt was placed therein.
After washing with cold water, it was washed with acetonitrile and dried under reduced pressure at room temperature.

Yield 10.7g, yield 79.4% Next, put DMF500mu in a beaker.

After dissolving and cooling the liquid temperature to 5°C, 8.5 g (0,020 mol) of the previously obtained borofluoride salt was dissolved, and then 5.1 g (0,050 mol) of triethylamine was added dropwise over 5 minutes. After stirring for 2 hours, the precipitated pigment was filtered, washed 4 times with DMF, then washed with water, replaced with acetone, and dried under reduced pressure at room temperature.

Yield 10.7g, yield 82.0%.

Melting point 300℃ or higher (decomposition) Elemental analysis Calculated value (%) Actual value (%) C6B, 2
0 68.29 N 15.05 14.950
12.29 12.21 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 can be prepared by forming a film on a conductive support by dispersing the above-mentioned disazo pigment in a suitable binder.

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 disazo pigment as possible in order to obtain sufficient absorbance and a thin film layer, e.g. 5 lumen, to shorten the range of the generated charge carriers. Hereinafter, it is preferable to use a thin film layer having a thickness of preferably 0.01 to 1 μm.

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 conductive support. The binder that can be used can be selected from a wide range of insulating resins, and poly- It can be selected from organic photoconductive polymers such as N-vinylcarbazole, polyvinylanthracene and polyvinylpyrene.

Preferably polyvinyl butyral, polyarylate (such as a 1ii polymer of hisphenol A and phthalic acid), polycarbonate, polyester, phenoxy resin, polyvinyl acetate, acrylic resin, polyacrylamide, polyamide, polyvinylpyridine, cellulose resin, polyurethane, epoxy Examples include insulating resins such as 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 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 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, toluene, xylene, ligroin, monochlorobenzene, dichlorobenzene, etc. aromatic hydrocarbons and the like can be used.

Coating methods include dip coating, spray coating, spinner coating, bead coating,
This can be carried out using a coating method such as a Mayer coating method, a blade coating method, 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) may be a substance to which the charge generation layer is sensitive. l
! Electromagnetic waves, which are preferably substantially insensitive to the wavelength range of magnetic waves, include a wide range of light rays, including gamma rays, Contains a definition.

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, bromoanil, tetracyanoethylene, tetracyanoquinodimethane, 2,4.7-)nitro-9- Fluorenone, 2
,4,5.7-tetranitro-9-fluorenone,2,
4.7-) dinitro-9-dicyanomethylenefluorenone, 2.4,5.7-titranitroxanthone, 2,4
．． Examples include electron-withdrawing substances such as 8-trinidrothioxanthone, and polymerization of these electron-withdrawing substances.

Examples of hole-transporting substances include pyrene, N-ethylcarbazole, N-inpropylcarbazole, N-methyl-N-
7-enylhydrazino-3-methylidene-9-ethylcarbazole, N,N-diphenylhydrazi/-3-methylidene-9-ethylcarbazole, N,N-diphenylhydrazino-3-methylidene-10-ditylphenothiazine, N , N-diphenylhydrazino-3-methylidene-
10-Ethyl 2-enoxacin, p-diethylaminobenzaldehyde-N, N-diphenylhydrazone, p-diethylaminobenzaldehyde-N-α-naphthyl-N
-Phenylhydrazone, p--pyrrolidinobenzaldehyde-N,N-'; Phenylhydrazone, 1,3.3-
Trimethylindolenine-ω-aldehyde-N,N-diphenylhydrazone, p-diethylbenzaldahyde-
Hydrazones such as 3-methylbenzthiazolinone-2-hydrazone, 2,5-bis(p-diethylaminophenyl)-1,3,4-oxadiazole, 1-phenyl-3-(p-diethylaminostyryl) -5-(p-diethylaminophenyl)pyrazoline, 1-[+noryl(
2)]-3-(p-diethylaminostyryl)-5-(
p-diethylaminophenyl)pyrazoline, 1-[pyridyl(2)]-3-(p-diethylaminostyryl)
-5-(p-diethylaminophenyl)pyrazoline, 1
-[6-medoxyviridyl(2)] -3-(p-
diethylaminostyryl) -5-(p-diethylaminophenyl)pyrazoline, l-[pyridyl(3)]-
3-(p-diethylaminostyryl)-5-(p-diethylaminophenyl)pyrazoline, 1-[lepidyl (2
)] -3-(p-diethylaminostyryl)-5
-(p-diethylami/phenyl)pyrazoline, 1-[
pyridyl(2)]-3-(p-diethylaminostyryl)-4-methyl-5-((p-diethylaminophenyl)pyrazoline, 1-[pyridyl(2)]-3-(α
-Methyl-P-diethylaminostyryl)-5-(p-
diethylaminophenyl)pyrazoline, 1-phenyl-
3-(p-diethylaminostyryl)-4-methyl-5
-(p-diethylaminophenyl)pyrazoline, 1-phenyl-3-(α-benzyl-p-diethylaminostyryl)-5-(p-diethylaminophenyl)pyrazoline, spiropyrazoline and other pyrazolines, α-phenyl-4-N, N-diphenylaminostilbene, N-
ethyl-3-(α-2enylstyryl)carbazole,
Styryl compounds such as 9-dibenzylaminobenzylidene-9H-fluorenone, 5-p-ditolylaminobenzylidene-5H-dibenzo[a,d]cycloheptene, 2-(p-diethylaminostyryl)-6-dinithylaminobenz Oxazole, 2-(p-diethylaminophenyl)-4-(p-dimethylaminophenyl)-
Oxazole compounds such as 5-(2-chlorophenyl)oxazole, ? -(p-diethylaminostyryl)
-thiazole compounds such as 6-dinithylaminobenzothiazole, triarylmethane compounds such as bis(4-diethylamino-2-methylphenyl)-2enylmethane, l,1-bis(4-N,N-diethylamino-
Polyarylalkanes such as 2-methylphenyl)hebutane, 1,1,2,2-tetrakis(4-N,N-dimethylamine-2-methylphenyl)ethane, triphenylamine, poly-N-vinylcarbazole , polydonylpyrene, polyvinylanthracene, polyvinylacridine, poly-9-vinylphenylanthracene, pyrene-formaldehyde resin, ethylcal/hesol-
Examples include formaldehyde resin.

In addition to these organic charge transport materials, inorganic materials such as selenium, selenium-tellurium, 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. Examples of resins that can be used as /Hingoo include acrylic resin, polyarylate, polyester, polycarbonate,
Polystyrene, acrylonitrile-butadiene copolymer, acrylonitrile-butadiene copolymer, polyvinyl butyral, polyvinyl formal, polysulfone,
Examples include insulating resins such as polyacrylamide, polyamide, and 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 gm, but the preferred range is 8 to 20 gm.
It is Lm. When forming the charge transport layer by coating, an appropriate coating method as described above can be used.

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

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

A subbing layer having barrier and adhesive functions can also be provided between the conductive support 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 μm, preferably 0.5 to 3 μm.
m is appropriate.

When using a photoreceptor in which a conductive support, a charge generation layer, and a charge transport layer are layered in the order of VL, and the charge transport material is an electron transport material, the surface of the charge transport layer must be positively charged; When exposed to light after being charged, electrons generated in the charge generation layer are injected into the charge transport layer in the exposed area, and then reach the surface and neutralize the positive charge, resulting in attenuation of the surface potential and a gap between the exposed area and the unexposed area. Electrostatic 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 support, 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 conductive support. 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.

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 to light after charging, the holes generated in the charge generation layer are injected into the charge transport layer in the exposed area. , then reaches the conductive support. On the other hand, electrons generated in the charge generation layer reach the surface, the surface potential attenuates, 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, styryl compounds, oxatures, thiazoles, triarylmethanes, polyarylalkanes, triphenylamine, and poly-N-vinylcarbazoles. A photosensitive film containing the disazo pigment shown in (1) above as a sensitizer for organic photoconductive substances such as organic photoconductive substances and inorganic photoconductive substances such as zinc oxide, cadmium sulfide, and selenium can be used. This photosensitive film is formed by coating these photoconductive substances and the disazo pigment together with a binder.

Furthermore, as another specific example of the present invention, the above general formula (1)
Examples include an electrophotographic photoreceptor in which a disazo pigment represented by the following formula is contained in the same layer as a charge transport substance. On this occasion,
In addition to the charge transport materials mentioned above, a charge transfer complex compound consisting of poly-N-vinylcarbazole and trinitrofluorenone can be used.

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, the disazo pigment represented by the general formula (1) may be used in combination to increase the sensitivity of the photoreceptor or to obtain a panchromatic photoreceptor.
It is also possible to use a combination of more than one kind, or a combination with a charge generating substance selected from known dyes and pigments.

The electrophotographic photoreceptor of the present invention can be used not only in electrophotographic copying machines, but also in a wide range of electrophotographic applications such as laser beam printers, CRT printers, LED printers, liquid crystal printers, and laser plate making.

[Example] Examples 1 to 28 Ammonia aqueous solution of casein (casein 1
1.2g, ammonia water 1g, water 222mJj) so that the film thickness after drying with a Mayer bar was 1.0pm.
Apply and dry.

Next, 5 g of exemplified pigment (1) was added to 9!5 g of cyclohexanone.
Butyral resin (butyralization degree 63 mol%) in mM2
g was added to the dissolved liquid and dispersed in a sand mill for 20 hours. This dispersion was applied onto the previously formed casein layer using a Mayer bar so that the film thickness after drying was 0.2 pm, and dried to form a charge generation layer.

5g of hydrazone compound and polymethyl methacrylate (
Dissolve 5 g of (number average molecular weight: 100,000) in 40 m of benzene, apply this onto the charge generation layer using a Mayer bar so that the film thickness after drying is 20 gm, and dry to form a charge transport layer. An electrophotographic photoreceptor of Example 1 was prepared.

Example 2 using other exemplary pigments in place of exemplary pigment (1)
Photoreceptors corresponding to items 1 to 28 were prepared in exactly the same manner.

The electrophotographic photoreceptor thus prepared was tested using an electrostatic copying paper tester (Model 5r-428, manufactured by Kawaguchi Denki ■).
The sample was corona-charged statically at -5 KV, held in a dark place for 1 second, and then exposed to light at an illuminance of 10 lux to examine its charging characteristics.

The charging characteristics are 1 surface type level (Vo) and the exposure i (
E 1/2) was measured. Show the results.

1 (1) 710 2.92
(2) 705 2.83 (4)
685 3.44 (5) 690
3.65 (6) 690 3.8
6 (7) 700 2.77
(9) 705 4.08 (10)
700 3.79 (11) 690
3.510 (13) 695 2.
911 (15) 700 3.012
(16) 700 3.213 (
17) 705 3.514 (18)
680 2.815 (20)
690 2.916 (21)
695 3.017 (23)
695 3.218 (24)
685 3.019 (26)
705 2.720 (28)
710 2.821 (29)
715 2.922 (31)
695 3.023 (33)
705 3.724 (34)
710 4.125 (35
) 685 2.826 (3
6) 720 3.027 (
37) 680 4.028
(38) 695 2.8 Comparative Examples 1 to 2 Photosensitive material corresponding to Comparative Example 1.2 was prepared in exactly the same manner as in Example 2, except that the disazo pigment of Example 2 was used in place of the disazo pigment represented by the following structural formula. A body was prepared and the charging characteristics were similarly evaluated. Show the results.

(Comparative Example 1) Disazo Pigment Vony 71QV El/2: 4.51ux, 5ee (Comparative Example 2) Disazo Pigment Vony 660V El/2: 4.1uux, see From the Examples and the above Comparative Examples, the following compounds were used in the present invention: It can be seen that the disazo pigment has extremely excellent sensitivity.

Examples 29 to 33 Using the photoreceptors used in Examples 4, 7, 10, 21, and 25, fluctuations in bright area potential and dark area potential were measured when using the edge-turning 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 the cylinder is driven. Using this copying machine, the initial bright area potential (VL) and dark area potential (
Vo) were set to around -200v and -700V, respectively, and the fluctuation amounts ΔVL and ΔvD in the bright area potential (VL) and dark area potential (VD) after 5,000 uses were measured.

Show the results.

Note that a negative sign in ΔvD and ΔVL represents a decrease in potential, and a positive sign represents an increase in potential.

29 4 -10 +2030
7 -15 +1531 10
0 +532 21 +5 +
1033 25 -10 +5 Comparative example 3
~・4 Regarding the photoreceptors used in Comparative Examples 1 and 2, the potential fluctuation during repeated use was reduced to ΔIII by the same method as in Example 29.
Established. Show the results.

3 1 -35 +754 2
-55 +90 From the above results, the electrophotographic photoreceptor of the present invention.

It can be seen that there is little potential fluctuation during reuse.

Example 34 Coating polyvinyl alcohol with a film thickness of 0.5 pm on the aluminum surface of an aluminum-based young polyethylene terephthalate film.
1 ji was formed.

Next, the dispersion of the disazo pigment used in Example 3 was placed on the polyvinyl alcohol layer formed previously so that the film thickness after drying was 0.
．． A charge generating layer was formed by coating with a Mayer bar to a thickness of 2 m and drying.

Next, a solution prepared by dissolving 5 g of the styryl compound represented by the structural formula and 5 g of polyarylate (condensation polymer of bisphenol A and terephthalic acid-inphthalic acid) in 40 ml of tetrahydrofuran was applied onto the charge generation layer so that the film thickness after drying was 18 tons. A charge transport layer was formed by coating and drying 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 29. Show the results.

vo knee 690V El/2: 2.6 flux, see ΔVD knee 15V ΔVL: +8V Example 35 A photoreceptor was prepared by applying the charge transport layer and charge generation layer of the photoreceptor prepared in Example 3 in the reverse order, Charging characteristics were evaluated in the same manner as in Example 1. However, the charging polarity was set to 10. Show the results.

vo: +705V El/2: 3.0 Sentence ux, see Examples 36-3
9 The photoreceptor prepared in Example 14.17.19.26 was
Exposure was performed using a semiconductor laser having an oscillation wavelength of 0 nm, and the sensitivity at 780 nm was examined. Show the results.

36 14 2.1 37 17 2.0 38 19 1.9 39 26 1.6 Example 40 On the charge generation layer prepared in Example 1, 5 g of 2,4.7-dolinitro-9-fluorenone and poly- A coating solution prepared by dissolving 5 g of 4,4-dioxydiphenyl-2,2-propane carbonate (molecular weight 300,000) in 70 ml of monochlorobenzene was applied so that the coating amount after drying was 12 g/m2, Dry.

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

Show the results.

Vo: +715V El/2: 4.3Jljux, sec Example 41 An ammonia aqueous solution of casein (described above) is placed on a 100gm thick aluminum plate! A cloth, dried, film thickness 0, 57g
A subbing layer of m was formed.

Next, 5 g of 2,4.7-)dinitro-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 exemplified pigment (2) Ig 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 coated on the subbing layer and dried to form a layer of 16 gm to prepare a photoreceptor.

Example 1 Charging characteristics of the electrophotographic photoreceptor thus prepared
It was measured in the same manner as. However, the charging polarity was set to 10.

Show the results.

Vo: +680V El/2: 4.61ux, see [Effects of the Invention] The electrophotographic photoreceptor of the present invention has improved carrier generation efficiency or carrier transport within the photosensitive layer by using a specific disazo resin in the photosensitive layer. One or both of the efficiency is improved, and the sensitivity and potential stability during long-term use are improved.

Claims (1)

[Scope of Claims] 1. An electrophotographic photoreceptor comprising a photosensitive layer containing a disazo pigment represented by the following general formula (1) on a conductive support. General formula ▲ Numerical formula, chemical formula, table, etc. ▼ (1) In the formula, Ar_1 and Ar_2 represent an aromatic hydrocarbon ring or a heterocycle which may have a substituent, and C_P_1 and C_P_2 are the same or different, It represents a coupler residue having a phenolic hydroxyl group, Z represents an oxygen atom or a sulfur atom, and n is an integer of 1 or 2. 2. At least 3 of the charge generation layer and charge transport layer containing a conductive support and a disazo pigment represented by general formula (1)
The electrophotographic photoreceptor according to claim 1, comprising a layer.