JPH01261647A - electrophotographic photoreceptor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

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 made of inorganic photoconductive materials, photoreceptors using selenium, cadmium sulfide, zinc oxide, etc. have been widely used.

On the other hand, electrophotographic photoreceptors made of organic photoconductive substances include photoconductive polymers typified by poly-N-vinylcarbazole and 2,5-bis(p-diethyl7minophenyl)-1,3,4-oxa Photoreceptors using low-molecular organic photoconductive substances such as diazole, and photoreceptors made by combining such organic photoconductive substances with various dyes and pigments are known.

An electrophotographic photoreceptor using an organic photoconductive substance has the advantage that it has good film-forming properties, can be produced by coating, has extremely high productivity, and can provide an inexpensive electrophotographic photoreceptor.

In addition, depending on the selection of sensitizers such as dyes and pigments used,
It has the advantage of being able to freely control color sensitivity,
A wide range of studies have been carried out, especially recently,
With the development of an a-part releasable photoreceptor, which has an organic photoconductive pigment as a charge generation layer and a VL charge transport layer made of the aforementioned photoconductive polymer or a low-molecular organic photoconductive substance, the conventional organic electronic Significant improvements have been made in sensitivity and durability, which were considered to be the shortcomings of photographic photoreceptors.1. It is now being put into practical use.

Many azo pigments have been proposed as charge-generating substances used in this type of photoreceptor, and an example of the azo pigment related to the present invention is phenanthrene described in JP-A-56-143437. Quinone-based disazo pigments and benzanthrone-based disazo pigments described in JP-A-61-219048 are already known.

However, photoreceptors using these disazo pigments have not always been satisfactory in terms of sensitivity and potential stability during repeated use.

[Problems to be Solved by the Invention] The objects of the present invention are to provide a novel photoconductive material and an electrophotographic photoreceptor having practical high sensitivity characteristics and stable potential characteristics during repeated use. It is in.

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

In the formula, A and A2 represent coupler residues having the same or different phenolic hydroxyl groups.

Preferred specific examples of coupler residues having a phenolic hydroxyl group represented by A, A2 include the following general formula (2
) to (6) are mentioned.

′・X′ In the formula, The fused ring of X is preferably a naphthalene ring, anthracene ring, carbazole ring, or benzcarbazole ring.

R1 and R2 are a hydrogen atom, a furkyl group that may have a substituent, an aryl group, an aralkyl group, a heterocyclic group, or R
, , indicates a cyclic ami7 group containing the nitrogen atom to which R2 is bonded in the ring, and examples of the furkyl group include methyl, ethyl, propyl, butyl, and the like.

Aryl groups include phenyl, diphenyl, naphthyl,
Groups such as anthryl, benzyl as aralkyl groups,
Groups such as phenethyl and naphthylmethyl, and heterocyclic groups include groups such as carbazole, dibenzofuran, penzimigzolone, benzthiazole, thiazole, and pyridine.

Z represents an oxygen atom or a sulfur atom.

n represents an integer of 0 or l.

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

The optional substituents of the furkyl group, aryl group, aralkyl group, alkoxy group, and heterocyclic group represented by R1 to R3 in general formulas (2) and (3) include 1, such as fluorine atom, chlorine atom, and iodine. atom, halogen atom such as bromine atom, alkyl group such as methyl, ethyl, propyl, isopropyl, butyl, alkoxy group such as methoxy, ethoxy, propoxy, phenoxy, nitro group, cyano group, dimethylamino, dibenzylamino, diphenylamino ,
Examples include substituted amine 7 groups such as 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 O-phenylene. Divalent group of aromatic hydrocarbons, 0-naphthylene, berinaphthylene, 1
．． 2-Anthrylene, 9. Examples include divalent groups of condensed polycyclic aromatic hydrocarbons such as to-phenanthrylene, and examples of divalent groups of heterocycles 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.

°゛x' In the formula, R4 represents an aryl group or a heterocyclic group which may have a substituent, and specific examples include phenyl, naphthyl, anthryl, pyrenyl, pyridyl, thienyl, furyl, and carbazolyl groups.

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, isopropyl, and butyl, methoxy, ethoxy, propoxy, and phenoxy Examples include substituted amino groups such as a flukoxy group, a nitro group, a cyano group, dimethylamino, dibenzylamino, diphenylamino, morpholino, piperidino, and pyrrolidino.

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

, Rr 'x' In the formula, R5 and R6 represent a hydrogen atom, an alkyl group which may have a substituent, an aralkyl group, an aryl group, or a heterocyclic group, and specifically, the alkyl group includes methyl, ethyl , propyl, butyl, aralkyl groups include benzyl, phenethyl, naphthylmethyl, aryl groups include phenyl, diphenyl, naphthyl, anthryl, heterocyclic groups include carbazolyl, thienyl, pyridyl, furyl, etc. Substituents for alkyl groups, aralkyl groups, aryl groups, and heterocyclic groups include halogen atoms such as fluorine atoms, chlorine atoms, iodine atoms, and bromine atoms, alkyl groups such as methyl, ethyl, propyl, impropyl, butyl, and methoxy , ethoxy, propoxy,
Alkoxy groups such as phenoxy, nitro groups, cyano groups,
Dimethylamino, dibenzylamino, diphenylamino.

Examples include substituted amine groups such as morpholino, piperidino, and pyrrolidino.

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

In particular, the coupler residues of A1 and A2 have the general formula (2),
When X in (5) and (6) is a coupler residue condensed with a benzene ring to form a benzcarbazole ring, the absorption range of the disazo pigment extends to around 800 nm, making it suitable for laser beam printers. can be used.

Representative examples of the trisazo pigment represented by the general formula (1) are listed below.

The description will show only A, A2 that changes in the basic type.

Basic Exemplary Pigment (1) Exemplary Pigment (2) Exemplary Pigment (3) Exemplary Pigment (5) CΩ Exemplary Pigment (7) Exemplary Pigment (8) υ Exemplary Pigment (9) Exemplary Pigment (10) Exemplary Pigment (11) Exemplified Pigment (12) Exemplified Pigment (13) Shimata Exemplified Pigment (14) b Exemplified Pigment (15) Exemplified Pigment (16) IL Exemplified Pigment (17) 6M Exemplified Pigment (18) Shimata Exemplified Pigment (19) Exemplified Pigment ( 20) F Note that the disazo pigment represented by general formula (1) is not limited to the range of the above-mentioned exemplified pigments.

The disazo pigment represented by the general formula (1) can be 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, N
-dimethylamide.

Sodium acetate, pyridine, triethylamine, triethanolamine, etc. in a solvent such as dimethyl sulfoxide.
It can be easily synthesized by coupling with the corresponding coupler in the presence of a base.

If A1 and A2 are different, synthesis can be performed by coupling the tetrazonium salt with the first coupler and then with the second coupler, or by protecting one of the 7-mino groups of the diamine with an acetyl group, etc. It can be synthesized by diazotizing this, coupling with a first coupler, hydrolyzing the acetyl group etc. with hydrochloric acid, diazotizing it again, and coupling with a second coupler.

Synthesis example (synthesis of exemplified pigment (10)) In a 300 mjl beaker, 150 ml of water and 20 ml of concentrated hydrochloric acid
Add (0,2:3 mol) and (0,032 mol), cool to 0℃, and add 4.6 g (0,067 mol) of sodium nitrite to 10 mfL of wood.
was added dropwise into the solution over a period of 10 minutes while controlling the temperature at 5° C. or lower. After one drop was added, the solution was stirred for 15 minutes, and then carbon was added and filtered. 10.5 g of sodium borofluoride (0,098-t-
A solution prepared by dissolving fluoroborate in 40 mJL of water was added dropwise, and the precipitated borofluoride salt was collected by filtration, washed with cold water, washed with acetonitrile, and dried under reduced pressure at room temperature.

Collection 1i114. Og, yield 78.0% Next, 500 mJl of DMF was placed in a 1M beaker, 11.2 g (0,020 mol) of borofluoride salt was dissolved, and then 5.1 g (0,050 mol) of triethylamine was added dropwise over 5 minutes. After adding 0 drops and stirring for 2 hours, the precipitated pigment was filtered and DMF
The sample was washed four times with water, then with water, and freeze-dried. Yield 19.
5g, yield 85%.

Melting point 300°C or higher (decomposition) Elemental analysis Calculated value (%) Actual value (%) C75,
2475,03 H3,873,94 N 9.75 9.88 A coating containing a disazo pigment represented by the above general formula (1)
No. 1 exhibits photoconductivity and therefore can be used in the photosensitive layer of an electrophotographic photoreceptor.

That is, in the present invention, the above-mentioned general formula (1) is formed on a conductive support.
An electrophotographic photoreceptor can be constructed by dispersing and containing the disazo pigment represented by the formula in a suitable binder to form a film.

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 generating layer contains as much of the aforementioned photoconductive trisazo pigment as possible to obtain sufficient absorbance;
In addition, in order to shorten the range of the generated charge carriers, a thin film layer, for example, 5 ILm or less, preferably 0.01 to Ig
A thin IIIi layer with a thickness of m is desirable.

This means that most of the incident light is absorbed by the charge generation layer, generating many charge carriers, and that the generated charge carriers must be injected into the charge transport layer without being deactivated by recombination or trapping. This is due to the fact that

As described above, the charge generation layer can be formed, for example, by dispersing the disazo pigment represented by the general formula (1) in a suitable binder and coating the disazo pigment on a conductive support.

Binders that can be used to form the charge generating layer by coating can be selected from a wide range of insulating resins, and can also be selected from organic photoconductive polymers such as poly-N-vinylcarbazole, polyvinylanthra7ane, and polyvinylpyrene. . Preferred are polyvinyl butyral and polyvinyl benzal.

Polyarylate (condensation polymer of bisphenol A and phthalic acid, etc.), polycarbonate, polyester, phenoxy resin, polyvinyl acetate, acrylic resin, polyacrylamide, polyamide, polyvinylpyridine, cellulose resin, urethane resin, casein, polyvinyl alcohol, polyvinyl Examples include insulating resins such as pyrrolidone.

The resin contained in the charge generation layer is suitably 80% by weight or more, 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 or undercoat layer described below.

Specific organic solvents include alcohols such as methanol, ethanol, and isopropanol, ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and dichlorohexanone, and N,N-dimethylformamide and N,N-dimethylacetamide. Amides, sulfoxides such as dimethyl sulfoxide, ethers such as tetrahydrofuran, dioxane, ethylene glycol monomethylene ether, esters such as methyl acetate and ethyl butyrate, chloroform, methylene chloride, dichloroethyle〉', carbon tetrachloride, trichloroethylene Aliphatic halogenated hydrocarbons such as benzene, toluene, xylene, ligroin, monochlorobenzene, dichlorobenzene and the like can be used.

Coating is done by dip coating method, spray coating method,
Bead coating method, Mayer-per coating method,
This can be done using a coating method such as a blade coating method.

For drying, it is preferable to dry to the touch at room temperature and then heat dry.Heat drying is performed at a temperature of 30 to 200°C for 5 minutes to 2 minutes.
It can be carried out stationary or under ventilation for a range of 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, the charge transport layer may be formed as an a layer on the charge generation layer, or may be laminated below it.

When the charge transport layer is formed on E of the charge generation layer, the material that transports charge carriers in the charge transport layer (hereinafter referred to as charge transport material) is the "yr" to which the charge generation layer is sensitive.
The electromagnetic waves referred to herein, which are preferably substantially insensitive to the A-wave wavelength range, include light rays in a broad sense, including gamma rays, X-rays, ultraviolet rays, visible light, near-infrared rays, infrared rays, far-infrared rays, etc. It includes the fixed shallowness of .

When the photosensitive wavelength range of the charge transport layer matches 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-dolinitro-9-fluorenone, 2
,4,5.7-tetranitro-9-fluorenone,2,
4.7-Dolinitro 9-dicyanomethylenefluorenone.

2.4,5.7-titranitroxanthone, 2°4.8
-) Electron-absorbing substances such as linitrothioxanthone, and polymerized products of these electron-withdrawing substances.

Examples of hole-transporting substances include pyrene, N-ethylcarbazole, N-isopropylcarbazole, and N-methyl-N-
Phenylhydrazino-3-methylidene-9-ethylcarbazole, N,N-diphenylhydrazino-3-methylidene-9-ethylcarbazole, N,N-diphenylhydrazino-3-methylidene-10-ethylphenothiazine, N,N -diphenylhydrazino-3-methylidene-
1O-Ethylphenoxazine, P-diethylaminobenzaldehyde-N, N-diphenylhydrazone, p-diethylaminobenzaldehyde-N-α-naphthyl-N
-Phenylhydrazone, p-pyrrolidinobenzaldehyde-N,N-diphenylhydrazone, l,3.3-trimethylindolenine-ω-aldehyde-N,N-diphenylhydrazone, P-diethylbenzaldehyde-3-
Hydrazones such as methylbenzthiazolinone-2-hydrazone, 2,5-bis(p-diethylaminophenyl)-1,3,4-oxadiazole, l-phenyl-3
-(p-diethylaminostyryl)-5-(p-diethylaminophenyl)pyrazoline, l-[quinolyl (2)
]-3-(p-diethyl 7-minostyryl)-5-(p-
diethylaminophenyl)pyrazoline, l-[pyridyl(2)]-3-(p-diethylaminostyryl)-5-
(p-diethyl7minophenyl)pyrazoline.

l-[6-medoxypyridyl (2)] -3-(p-
diethylaminostyryl)-5-(p-diethylaminophenyl)pyrazoline, i-(pyridyl(3)) -3
-(p-diethylaminostyryl)-5-(p-diethylaminophenyl)pyrazoline, l-[lepidyl (2)
] -3-(p-diethyl 7-minostyryl)-5-(p
-diethyl7minophenyl)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, l-phenyl-3-(p-
diethylaminostyryl)-4-methyl-5-(p-diethylaminophenyl)hilazoline, l-phenyl-3
-(α-benzyl-p-diethylaminostyryl)-5
-(p-diethylaminophenyl)pyrazoline, spiropyrazoline and other pyrazolines, α-phenyl-4-N
, N-diphenyl7-minostilbene, N-ethyl-3-
(α-phenylstyryl)carbazole, 9-dibenzylaminobenzylidene-9H-fluorenone, 5-p-
Ditolylaminobenzylidene-5H-dibenzo [a, d
l Styryl compounds such as cycloheptene, 2-(p
-diethylaminostyryl)-6-dinithyl 7minobenzoxazole, 2-(p-diethylaminophenyl)
-Oxazole compounds such as -4-(p-dimethylaminophenyl)-5-(2-chlorophenyl)oxazole, 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, 1,1,2.2tetrakis(4-N,
Poly7lyl alkanes such as N-dimethylamino-2-methylphenyl)ethane, triphenylamine, polyN-vinylcarbazole, polyvinylpyrene, polyvinylanthracene, polyvinylacridine, poly-9-
Vinyl anthracene, pyrene-formaldehyde resin,
Examples include ethyl carbazole formaldehyde resin.

In addition to these organic electrotransport materials, inorganic materials such as selenium, selenium-tellurium, amorphous silicon, and cadmium sulfide can also be used.

Further, these charge transport substances 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,
1! ! Examples include insulating resins such as bare rubber, and organic photoconductive polymers such as poly-N-vinylcarbazole, polyvinyl 7-thracene, and polyvinylpyrene.

Since the charge transport layer has a limit in its ability to transport charge carriers, it cannot be made thicker than necessary.-The thickness is 5 to 30 pm, but the preferred range is 8 to 20 pm.
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 a laminated structure of a charge generation layer and a charge transport layer is provided on a conductive support.

As the conductive support, the support itself has conductivity,
For example, aluminum, aluminum alloy, copper, zinc, stainless steel, vanadium, molybdenum, chromium, titanium,
Nickel, indium, gold, platinum, etc. can be used, and other materials include plastin, which has a layer formed by vacuum deposition of aluminum, aluminum alloy, indium oxide, tin oxide, indium oxide-tin oxide alloy, etc. (e.g., polyethylene, polypropylene, polyvinyl chloride, polyethylene terephthalate, acrylic resin, polyfluoroethylene, etc.) and conductive particles (e.g., carbon black, silver particles, etc.) together with a suitable binder on plastic or the aforementioned conductive support. A coated support, a support in which plastic or paper is impregnated with conductive particles, a plastic having a conductive polymer, etc. can be used.

A subbing layer having barrier and adhesive functions may also be provided between the conductive support 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, alkoxymethylated nylon, etc.), polyurethane, gelatin, aluminum oxide, etc. can.

The thickness of the subbing layer is 0.1 to 5 pm, preferably 0.5 to 5 pm.
3 m is appropriate.

When using a photoreceptor in which a conductive support, a charge generation layer, and a charge transport layer are laminated in this order, and the charge transport material is an electron transport material, the surface of the charge transport layer must be positively charged; 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 static electricity 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. Fix this directly or
Alternatively, the toner image can be transferred to paper or plastic film, developed, and fixed.

After transferring the electrostatic latent image on the photoreceptor to the insulating layer of transfer paper,
A method of developing and fixing can also be used. The type of developer, developing method, and fixing method may be any known developer or known method, and are not limited to a specific one.

On the other hand, when the charge transport material is a hole transport material, it is necessary to charge the surface of the charge transport layer negatively, and when exposed to light after charging, the genuine tag generated in the charge generation layer is injected into the charge transport layer in the exposed area. , then reaches the surface and neutralizes the negative charges, resulting in attenuation of the surface potential and an electrostatic contrast with the unexposed area.

For development special programs, it is necessary to use a positively charged toner, contrary to the case where an electron transporting substance is used.

When using a photoreceptor in which a conductive support, a charge transport layer, and a charge generation layer are laminated in this order, and the charge transport substance is an electron transport substance, the surface of the charge generation layer must be negatively charged; 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,'! The holes generated in the charge generation layer reach the surface and the surface potential is attenuated, 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. Fix this directly or
Alternatively, the toner image can be transferred to paper or plastic film, developed, and fixed.

After transferring the electrostatic latent image on the photoreceptor to the insulating layer of transfer paper,
A method of developing and fixing can also be used. The type of developer, developing method, and fixing method may be any known developer or known method, and are not limited to a specific one.

On the other hand, when the charge transport material is made of a hole transport material, it is necessary to positively charge the surface of the charge generation layer, and after charging, when R light is applied, the holes generated in the charge generation layer are released in the exposed area. It is injected into the charge transport layer and then reaches the conductive support.

On the other hand, the electrons generated in the charge generation layer reach the surface and 1
Attenuation of the surface potential occurs, creating an electrostatic contrast with 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, the above-mentioned hydrazones, pyrazolines, styryl compounds, oxatures, thiazoles, triarylmethanes, poly7arylalkane, tri-2enylamine, poly-N-vinylcarbazole The photosensitive coating may contain a disazo pigment represented by the above-mentioned general formula (1) as a sensitizer for organic photoconductive substances such as the following and inorganic photoconductive substances such as zinc oxide, cadmium sulfide, and selenium.

This photosensitive coating is made of these photoconductive substances and the general formula (
A film is formed by coating the disazo pigment shown in 1) together with a binder.

Further, as the electrophotographic photoreceptor of the present invention, the general formula (
Examples include an electrophotographic photoreceptor containing a disazo pigment shown in 1) in the same layer as 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 charge transport substance.

The electrophotographic photoreceptor of this example is manufactured by dispersing the disazo pigment represented by the general formula (1) and the charge transfer complex compound in a polyester solution dissolved in tetrahydrofuran, and then forming a film thereon.

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

If necessary, two or more types of disazo pigments represented by the general formula (1) may be used in combination for the purpose of increasing the sensitivity of the photoreceptor or obtaining a panchromatic photoreceptor by using a combination of pigments with different light absorptions. Alternatively, it may 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 in electrophotographic copying machines, laser beam 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 20 A solution in which 5 g of methoxymethylated 6-nylon (average molecular weight 32,000) and alcohol-soluble copolymerized nylon resin (average molecular weight 29,000) log were dissolved in 95 g of methanol was placed on an aluminum plate. was applied with a Mayer bar, and the film thickness after drying was 1.
A subbing layer having a value of 0 JLm was provided.

Next, 5 g of the above-mentioned exemplary pigment (1) was added to 95 g of cyclohexanone.
Butyral resin (butyralization degree 63 mol%) in mJl
2 g was added to the dissolved liquid and dispersed with a sand mill for 20 hours. This dispersion was applied onto the previously formed subbing layer using a Mayer bar so that the film thickness after drying was 0.2 p.m, and dried to form a charge generation layer.

5g of hydrazone compound and polymethyl methacrylate (
5 g of number average molecular weight lO 0,000) and 40 mjl of chlorobenzene
and apply this solution onto the charge generation layer so that the film thickness after drying is 2.
The electrophotographic photoreceptor of Example 1 was prepared by applying the coating to a layer of 0 #Lm using Mayer Per and drying to form a charge transport layer.

Electrophotographic photoreceptors corresponding to Examples 2 to 20 were prepared using the following exemplified pigments in place of exemplified pigment (1) and in the same manner as in Example 1 except for the other conditions.

The electrophotographic photoreceptor thus prepared was statically charged with corona at 15 KV using an electrostatic copying paper tester (Kawaguchi Denki 1Mode 5P-428), held in a dark place for 1 second, and charged with halogen. It was exposed to light using a lamp at an illuminance of 10 lux, and the charging characteristics were examined.

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

-6 V -V E 1/2 1uxse
c1 (1) 690 1.52
(2) 690 1.33 (
3) 700 1.74 (4) 7
00 1.95 (5) 710
1.66 (6) 700
1.57 (7) 690
1.88 (8) 700
2.09, (9) 7
10 2.610 (1,0)
700 2.311 (11)
700 1.812 (12
) 705 1.713 (
13) 690 1.414
(14) 695 2.115
(15) 700 2.016
(16) 700 1.9
17 (17) 705 2
．． 518 (18) 700
2.719 (19) 690
2.020 (20) 690
2.3 Comparative Examples 1 and 2 In place of the exemplary pigment (1) used in Example 1, disazo pigments and trisazo pigments shown by the following structural formulas were used, and the others were as follows:
A photoreceptor was prepared in exactly the same manner as in Example 1, and the same evaluation results were obtained.

In the case of Comparative Example 1, the comparative azo pigment vo knee 700V El/2: 3.71 Lux, sec In the case of Comparative Example 2, the comparative azo pigment vo knee 695V El/2: 3.6 uux, sec From the above results, it can be seen that the electron of the present invention It can be seen that the photographic photoreceptor has superior sensitivity compared to the electrophotographic photoreceptor of the comparative example.

Examples 21 to 25 Using the electrophotographic photoreceptors prepared in Examples 1.5, to, io, and 13.15, fluctuations in bright area potential and dark area potential during repeated use were measured.

The measurement method was to attach a photoreceptor 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 copying machine, the first clear ffrm (VL)
The t*i potential (Vo) is set to 200V.

Amount of variation ΔvL in bright area potential (VL) and dark area potential (CVv) after setting around -70QV and using it 5,000 times
, ΔVD was measured. In addition, ΔVL.

A negative sign in ΔVD indicates a decrease in potential, and a positive sign indicates an increase in potential.

21 1 -20 +1022 5
-10 +523 10 -10
+1524 13 -15 +
5 Comparative Examples 3 and 4 The electrophotographic photoreceptor prepared in Comparative Example 1.2 was evaluated for potential fluctuation during repeated use in the same manner as in Example 21. Show the results.

3 1 -50 +1204 2
-70 +95 From the above results, it can be seen that the electrophotographic photoreceptor of the present invention exhibits extremely small potential fluctuations during repeated use compared to the electrophotographic photoreceptor of the comparative example.

Example 26 A polyvinyl alcohol film having a thickness of 0.5 ILm was formed on the aluminum surface of an aluminum vapor-deposited polyethylene terephthalate film.

Next, the disazo pigment dispersion used in Example 13 was applied onto the previously formed polyvinyl alcohol layer using a Mayer bar so that the film thickness after drying was 0.2 gm, and dried to form a charge generation layer. Formed.

A solution prepared by dissolving 5 g of the compound and 5 g of polyarylate (condensation polymer of bisphenol A and terephthalic acid-isophthalic acid) in 40 ml of tetrahydrofuran was applied onto the charge generation layer so that the film thickness after drying was 20 pm, and dried. A charge transport layer was formed.

The charging characteristics and durability characteristics of the electrophotographic photoreceptor thus prepared were measured in the same manner as in Examples 1 and 21. Show the results.

El/2: 0.7 iux, see ΔvD knee 5v, ΔvL: +5v Example 27 A photoreceptor was prepared by applying the charge generation layer and charge transport layer of the photoreceptor prepared in Example 1 in the reverse order, and the photoreceptor was prepared in Example 1. The charging characteristics were evaluated in the same manner as in Example 1. The charging polarity at this time was set to 10.

VO: +710V El/2: 2.6 x ux, sec Example 28 On the charge generation layer formed in Example 1, 5 g of 2,4.7-dolinitro-9-fluorenone and poly-4,4°-di A coating solution prepared by dissolving 5 g of oxydiphenyl-2,2-propane carbonate (molecular weight: 300,000) in 70 mJl of chlorobenzene was applied and dried so that the coating amount after drying was 12 g/m2.

The charging characteristics of the electrophotographic photoreceptor thus prepared were measured in the same manner as in Example 1.

The charging polarity at this time was set to 10. Show the results.

vo: +675V El/2:4.2JLux, see Example 29 An ammonia aqueous solution of casein was applied on an aluminum plate with a thickness of 100 μm and dried to form a subbing layer with a thickness of 0.5p and m.

Next, 5 g of 2,4.7-dolinitro-9-fluorenone
and 5 g of poly-N-vinylcarbazole (number average molecular weight: 300,000) were dissolved in 70 ml of tetrahydrofuran to form a charge transfer complex compound.

This charge transfer complex compound and 1 g of Exemplary Pigment (2) were added to a solution in which 5 g of polyester (trade name: Vylon, manufactured by Sokushobo Co., Ltd.) was dissolved in 70 ml of tetrahydrofuran, and dispersed. This dispersion was applied onto the undercoat layer so that the film thickness after drying was 161 Lm and dried.

Example 1 Charging characteristics of the electrophotographic photoreceptor thus prepared
Measured using the same method as above. The charging polarity at this time was set to 10. Show the results.

VO: +650V El/2: 5.01ux, see [Effects of the Invention] The electrophotographic photoreceptor of the present invention uses a specific disazo pigment in the photosensitive layer, thereby improving carrier generation efficiency or carrier transport efficiency inside the photosensitive layer. This electrophotographic photoreceptor is improved in either or both of the above, and has excellent sensitivity and potential stability during long-term use.

Claims (1)

[Scope of Claims] 1. An electrophotographic photoreceptor having a photosensitive layer on a conductive support, characterized in that the photosensitive layer contains a disazo pigment represented by the following general formula (1). ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (1) In the formula, A_1 and A_2 represent coupler residues having the same or different phenolic hydroxyl groups. 2. The electrophotographic photoreceptor according to claim 1, wherein at least two layers, a charge generation layer and a charge transport layer containing a disazo pigment represented by formula (1), are provided on a conductive support.