JPH01204050A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To enhance practicable sensitivity characteristics and potential characteristics at the time of repeated uses by using a specified azo pigment for a photosensitive layer. CONSTITUTION:The photosensitive layer formed on a conductive substrate contains at least one of the azo pigments represented by formula II in which Ar is an optionally substituted aromatic hydrocarbon group or aromatic heterocyclic group combined optionally through a bonding group with at least one of the groups represented by formula I in which X is an atomic group necessary to condense with the benzene ring and to form a ring; n1 is 0 or 1; and n is an integer of 1-4. Said azo pigment is obtained by reacting a corresponding acid halide with a ureido compound and producing a coupler component, thus permitting practicable high sensitivity characteristics and stable potential characteristics at the time of repeated uses to be obtained.

Description

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

[Prior Art] Electrophotographic photoreceptors using inorganic photoconductors such as selenium, cadmium sulfide, and zinc oxide as photosensitive components have been known.

On the other hand, since the discovery that certain organic compounds exhibit photoconductivity, many organic photoconductors have been developed. , anthracene, pyrazolines, oxadiazoles, yodracines, polyaryl alkanes, and other low-molecular organic photoconductors, phthalocyanine pigments, azo pigments, cyanine dyes, polycyclic bovine pigments, perylene pigments, and indigo dyes. ,
Organic pigments and dyes such as thioindigo dyes and methine squaric acid dyes are known. In particular, organic pigments and dyes with photoconductivity are easier to synthesize than inorganic materials, and the variety of compounds that exhibit photoconductivity in an appropriate wavelength range has expanded. Organic pigments and dyes have been proposed.

For example, U.S. Pat. No. 4,123,270, U.S. Pat.
47614 specification, 4251613 specification, 4251614 specification, 4256821 specification, 4260672 specification, 4268596
Specification of No. 4278747, No. 4293
628, an electrophotographic photoreceptor using an azo pigment exhibiting photoconductivity as a charge generation substance in a photosensitive layer functionally separated into a charge generation layer and a charge transport layer is known.

Electrophotographic photoreceptors using such organic photoconductors can be produced by coating by appropriately selecting a binder, making it possible to provide photoreceptors with extremely high productivity and low cost. Although this photoreceptor has the advantage of being able to freely control the wavelength range to which it is sensitive, it has one problem in that only a few of these photoreceptors can be put to practical use in terms of sensitivity and durability.

Conventional azo pigments include compounds having an amide structure at the coupler site (for example, JP-A-47-37543, JP-A-58-122967) and compounds having a hydrazone structure (for example, JP-A-56-94358). However, as a result of studies to solve the above-mentioned problems, the present inventors have found that it is extremely effective when a compound having the structure represented by the following general formula (I) is used as a coupler. I found it.

[Problems to be Solved by the Invention] An object of the present invention is to provide a novel electrophotographic photoreceptor, and to provide an electrophotographic photoreceptor that has practical high sensitivity characteristics and stable potential characteristics during repeated use. It is.

[Means for Solving the Problems, Effects] The present invention provides a substituted or unsubstituted aromatic carbonized organic residue represented by the following general formula (I) that may be bonded to a conductive support via a bonding group. It is composed of an electrophotographic photoreceptor characterized by having a photosensitive layer containing an azo pigment having a structure bonded to a hydrogen group or an aromatic heterocyclic group.

``'x'' In the formula, Indicates an optional aromatic hydrocarbon group or aromatic heterocyclic group.

The above-mentioned specific azo pigment of the present invention has the following general formula % where Ar represents a substituted or unsubstituted aromatic hydrocarbon group or aromatic heterocyclic group which may be bonded via a bonding group. , n is an integer of 1.2.3 or 4. In addition,
X and R1 have the same meanings as in general formula (I).

Specifically, X is an aromatic hydrocarbon such as naphthalene, anthracene, carbazole, benzcarbazole, dibenzocarbazole, dibenzofuran, benzonaphthofuran, fluorenone, diphenyl sulfide, etc., which may be condensed with a benzene ring and have a substituent. or a residue necessary to form an aromatic heterocyclic group, and R1 includes aromatic hydrocarbon groups such as benzene, naphthalene, fluorene, phenanthrene, anthracene, and pyrene, which may have substituents, and furan. , thiophene, pyridine, benzothiazole, carbazole, dibenzothiophene,
Examples include aromatic heterocyclic groups such as benzoxazole, benzotriazole, oxadiazole, and thiadiazole.

Substituents for X and R1 above include alkyl groups such as methyl, ethyl, and propyl, flukoxy groups such as methoxy and ethoxy, substituted amino groups such as diethylamino and dimethylamino, and halogens such as fluorine, chlorine, and bromine atoms. Examples include atoms, nitro groups, cyano groups, and halomethyl groups such as trifluoromethyl.

Examples of Ar (substituted or unsubstituted aromatic hydrocarbon group or aromatic heterocyclic group to which the organic residue represented by general formula (I) may be bonded via a bonding group) include benzene, naphthalene, and fluorene. , phenanthrene, anthracene, pyrene, and other aromatic hydrocarbon groups; and aromatic heterocyclic groups such as furan, thiophene, pyridine, indole, benzothiazole, carbazole, acridone, dibenzothiophene, benzoxazole, benzotriazole, oxadiazole, and thiadiazole. , and further bonded directly or with an aromatic or non-aromatic group to the above aromatic group, such as triphenylamine, diphenylamine,
N-methyldiphenylamine, biphenyl, terphenyl, binaphthyl, fluorenone, phenanthrenequinone, anthraquinone, benzanthrone, diphenyloxadiazole, phenylbenzoxazole, diphenylmethane, diphenylsulfone, diphenyl ether,
Examples include benzophenone, stilbene, distyrylbenzene, tetraphenyl-p-phenylenediamine, and tetraphenylbenzidine.

Substituents for the above Ar include alkyl groups such as methyl, ethyl, propyl, and butyl, flukoxy groups such as methoxy and ethoxy, dialkylamino groups such as diethylamino and dimethylamino, and halogen atoms such as fluorine, chlorine, and bromine atoms. Atom, hydroxy group, nitro group,
Cyano group, halomethyl group or general formula -1*N-0p
Examples include substituted azo groups represented by (m) (wherein Cp represents a coupler residue having a phenolic hydroxyl group).

Preferred examples of Cp in the above general formula (m) include groups having the structure shown in the following general formula.

゛. A hydrogen atom, an alkyl group that may have a substituent, an aralkyl group, an aryl group, a heterocyclic group, or a cyclic amine group containing a nitrogen atom to which R2 and R3 are bonded in the ring, R4 and R5 are hydrogen atoms, represents an alkyl group, aralkyl group, aryl group or heterocyclic group which may have a substituent, R6 represents an alkyl group, aralkyl group, aryl group or heterocyclic group which may have a substituent,
Yl represents a divalent aromatic hydrocarbon group or a heterocyclic group which may have a substituent, and includes Y, '-1=-CYL, Y2 may have a substituent 2 represents a valent aromatic hydrocarbon group, such as o-phenylene, 0-naphthylene, perinaphthylene, 1,2-antrylene, 9,10-phenanthrene, etc., and Yl may have a substituent. Indicates a valent aromatic hydrocarbon group or a divalent heterocyclic group containing a nitrogen atom in the ring, and as a divalent aromatic hydrocarbon group, 0-
Phenylene, 0-naphthylene, berinaphthylene, l, 2
-Anthrylene, 9,10-phenanthrene, and other divalent heterocyclic groups containing a nitrogen atom in the ring include 3,4-pyrazolediyl, 2,3-pyridinediyl, and 4,5-pyrimidinediyl. , 6.7-indazolediyl, 5.6-benzimidazolediyl, 6.7-chiralindiyl, etc., Z represents an oxygen atom or a sulfur atom, B represents an oxygen atom, a sulfur atom or an N-substituted group, It represents an unsubstituted imino group, and the N-substituted group includes an alkyl group, an aralkyl group, an aryl group, etc. which may have a substituent.

Examples of the alkyl group in the above expression include methyl, ethyl, propyl, butyl, etc., aralkyl groups include benzyl, phenethyl, naphthylmethyl, etc., and aryl groups include phenyl, diphenyl, naphthyl, anthryl, etc. Examples of heterocyclic groups include pyridyl, thienyl, furyl, thiazolyl, carbazolyl, dibenzofuryl, benzimidazolyl, and benzothiazolyl, and examples of cyclic amine groups containing a nitrogen atom in the ring include pyrrole and viroline.

Examples include cyclic amino groups derived from pyrrolidine, pyrrolidone, indole, indoline, inindole, carbazoledole, imidazole, pyrazole, pyrazoline, oxazine, phenoxazine, benzocarbazole, and the like.

The substituents in the above expressions include alkyl groups such as methyl, ethyl, and propyl; alkoxy groups such as methoxy and nidoxy; halogen atoms such as fluorine, chlorine, bromine, and iodine; and fulkylamino groups such as dimethylamino and diethylamino. , phenylcarbamoyl group, nitro group, cyano group, halomethyl group such as trifluoromethyl.

Representative examples of specific azo pigments used in the present invention are listed below.

Exemplary pigment (1-1) O N -@- N Combined N = N - A Exemplary pigment (1-2) Exemplary pigment (2-1) Exemplary pigment (2-2) A-N-N-@-C )l-C)l-@-N-NA Exemplary pigment (2-3) 0M A-N-s+cH crystal+N-NA Exemplary pigment (2-4) Exemplary pigment (2-5) Exemplary pigment ( 2-6) Exemplary Pigment (2-7) Rough Exemplary Pigment (2-8) Exemplary Pigment (2-9) IHE Exemplary Pigment (2-10) Exemplary Pigment (2-11) Exemplary Pigment (2-12) Exemplary Pigment Pigment (2-13) Exemplary Pigment (2-14) Exemplary Pigment (2-15) Exemplary Pigment (2-16) Exemplary Pigment (2-17) Exemplary Pigment (2-18) Exemplary Pigment (2-19) Exemplary Pigment Pigment (2-20) Exemplified pigment (2-21) Exemplified pigment (2-22) Exemplified pigment (2-23) −
24) Exemplary Pigment (3-1) Exemplary Pigment (3-2) Exemplary Pigment (3-3) The following general 2〇 is used for the synthesis of The coupler component represented by m) has the general formula (XIV)
The acid ureido compound represented by the formula (W) and the corresponding acid halide compound represented by the general formula (W) can be easily synthesized using known methods.

(Xllll) 01! ! 1) (XV
) (In the formula, R1 and X have the same meanings as in general formula (I), and or once the diazonium salt of the corresponding amine compound has been isolated in the form of a salt such as a borofluoride salt or a zinc chloride double salt, for example with N,N-dimethylformamide, It can be produced by coupling in an organic solvent such as dimethyl sulfoxide in the presence of a base such as sodium acetate, pyridine, or triethylamine.

Among the above-mentioned specific azo pigments, in the case of disazo pigments, trisazo pigments, and tetrakisazo pigments, if one or more coupler components represented by general formula (XI) are contained in the same molecule, other couplers may be used. It may contain ingredients.

The synthesis method in this case is to diazotize the amine compound represented by the general formula (XV), couple it with the coupler represented by the general formula (XV), and then synthesize (CHiCONH), -Ar-(MHz)J (
X Vl ) (wherein Ar has the same meaning as general formula 1), m represents an integer of 1.2 or 3, and i + m is 2, 3 or 4) Hydrolyzed with mineral acids such as hydrochloric acid, obtained, diazotized again, and coupled with another coupler having a phenolic hydroxyl group to synthesize, or Ar-CNHz)vL(X■) (wherein Ar has the same meaning as general formula (II), n is an integer of 2.3 or 4) is made into a diazonium salt by a conventional method, and a solution obtained by mixing and dissolving the coupler represented by the above general formula (XI) and another coupler. Synthesis may also be carried out by coupling within.

Alternatively, the first coupler component is first coupled,
After forming a monoazo compound, a corresponding azo pigment may be synthesized by sequentially adding couplers one component at a time for coupling.

Synthesis example (synthesis of exemplified pigment (2-1)) 200 mJl of water and 48 m of concentrated hydrochloric acid in a 500mJ1 beaker
Add fL (0.54 mol) and while cooling in an ice water bath,
Add 20.0 g (0,082 mol) of 0-dianisidine and bring the temperature to 0 to 3°C while stirring. A solution of 12.0 g (0,174 mol) of 0-order sodium nitrite dissolved in 20 mJl of water It was added dropwise over 10 minutes while keeping the liquid temperature below 5°C. After the dropwise addition was completed, 5 g of activated carbon was added to the reaction solution which was stirred for another 30 minutes at the same temperature. After discharging, sodium borofluoride 27. A solution of 246 mol) dissolved in 40 m of water was added dropwise, and the precipitated borofluoride salt was collected by filtration.

After washing with water, it was vacuum dried.

Yield: 29.4 g, Yield: 81% Next, put 200 ml of DMF into a 500 ml beaker, dissolve 6.13 g (0.02 mol) of the compound having the following structure, and cool the liquid temperature to 5°C to obtain the previously obtained Borofluoride salt 4.24g (0,0096
mol), then 1.94 g of triethylamine
(0,0192 mol) was added dropwise over 10 minutes and then stirred for 2 hours. The reaction solution was filtered, washed 4 times with 200 m of N,N-dimethylformamide, further washed 3 times with water, and then freeze-dried. The target pigment was obtained.

Yield 7.18g, yield 85.0% (borofluoride salt base) Elemental analysis Calculated value (%) Actual value (%) C68.1
96B, 23 H4,354,37 N 12.72 12.65 The coating containing the azo pigment described above exhibits photoconductivity and can therefore be used in the photosensitive layer of the electrophotographic photoreceptor described below.

In a preferred embodiment of the present invention, it is used as a charge generating material in an electrophotographic photoreceptor in which the photosensitive layer of the electrophotographic photoreceptor is functionally separated into a charge generation layer and a charge transport layer.

Certain azo pigments mentioned above can be used.

The charge generation layer contains as much charge generation material as possible in order to obtain sufficient absorbance, and is a thin film layer, for example, 5 microns or less, preferably 0°, in order to shorten the traveling distance of the generated charge carriers. It is preferable to form a thin film layer with a thickness of 0.01 to 1 micron.

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 are not deactivated by recombination or trapping, but are transferred to the charge transport layer. This is due to the need for injection.

The charge generating layer can be formed by dispersing the above-mentioned specific azo pigment in a suitable binder and coating it on the conductive material.

Binders that may be used in forming the charge generating layer with IL&, I can be selected from a wide variety of insulating resins and organic photoconductive polymers such as poly-N-vinylcarbazole, polyvinylanthracene, and polyvinylpyrene. Preferably polyvinyl butyral, polyvinyl benzal, polyarylate (bisphenol A
and phthalic acid condensation polymers, etc.), polycarbonate, polyester, phenoxy resin, polyvinyl acetate, acrylic resin, polyacrylamide, polyamide, polyvinylpyridine, cellulose resin, urethane resin, casein,
Examples include insulating resins such as 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.

Coating is done by dip coating method, spray coating method,
Spinner coating method, bead coating method, Meyer bar coating method, plate coach ink method,
This can be carried out using a coating method such as a roller coach ink method or a curtain 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 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 isopropyl alcohol, acetone,
Ketones such as methyl ethyl ketone and cyclohexanone, amides such as N,N-dimethylformamide and N,N-dimethylacetamide, sulfoxides such as dimethyl sulfoxide, tetrahydrofuran, dioxane,
Ethers such as ethylene glycol monomethyl ether, esters such as methyl acetate and ethyl acetate, aliphatic halogenated hydrocarbons such as chloroform, methylene chloride, dichloroethylene, carbon tetrachloride, trichlorethylene, benzene, toluene, xylene, Aromatics such as ligroin, monochlorobenzene, dichlorobenzene, etc. can be used.

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.

In this case, the charge transport layer may be laminated on or below the charge generation layer.

However, it is desirable that the charge transport layer is laminated on the charge generation layer.

Since the photoconductor generally has the function of transporting charge carriers, the charge transport layer can be formed by the photoconductor.

The substance that transports charge carriers in the charge transport layer (hereinafter referred to as charge transport material) is preferably substantially insensitive to the wavelength range of electromagnetic waves to which the charge generation layer is sensitive.

The electromagnetic waves referred to here include a broad definition of light including gamma rays, X-rays, ultraviolet rays, visible light, near infrared rays, infrared rays, far infrared rays, etc. When they match or overlap with those of the generation layer, the charge carriers generated in both capture each other,
As a result, this causes a decrease in sensitivity.

Charge-transporting substances include electron-transporting substances and hole-transporting substances, and electron-transporting substances include chloranil, bromoanil, tetracyanoethylene 1, tetracyanoquinodimethane, 2,4,7-dolinitro-9-fluorenone,
2,4,5.7-tetranitro-9-fluorenone, 2
, 4.7-)nitro-9-dicyanomethylenefluorenone, 2.4,5.7-titranitroxanthone, 2.
Examples include electron-withdrawing substances such as 4.8-trinidrothioxanthone, and polymerization of these electron-withdrawing substances.

Pyrene, N-ethylcarbazole, N-isopropylcarbazole, N-methyl-N-
Phenylhydrazino-3-methylidene-9-ethylcarbazole, N,N-diphenylhydrazino-3-methylidene-9-ethylcal/<sol, N,N-diphenylhydrazino-3-methylidene-10-ditylphenothiazine, N,N-diphenylhydrazino-3-methylidene-10-ethylphenoxazine, p-diethylaminobenzaldehyde-N,N-diphenylhydrazone, p-
Diethylaminobenzaldehyde-N-α-naphthyl-
N-phenylhydrazone, p-pyrrolidinobenzaldehyde N, N-diphenylhydrazone, 1,3.3-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-7enyl-3-(p-diethylaminostyryl)- 5-(p-diethylaminophenyl)pyrazoline, 1-[quinolyl(2
)]-3-(p-diethylaminostyryl)-5-(p
-diethylaminophenyl)pyrazoline, l-[pyridyl(2)]-3-(p-diethylaminostyryl)-5
-(p-diethylaminophenyl)pyrazoline, 1-[
6-Medoxypyridyl(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-diethylaminophenyl)pyrazoline, 1-[pyridyl (2)]
-3-(p-diethylaminostyryl)-4-methyl-
5-(p-diethylaminophenyl)pyrazoline, 1-
[Pyridyl (2)] -3-(α-Methyl-p-diethylaminostyryl)-5-(p-diethylaminophenyl)pyrazoline, 1-phenyl-3-(p-diethylaminostyryl)-4-methyl-5-( p-diethylaminophenyl)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-phenylstyryl)carbazole, 9-dibenzylaminobenzylidene-9H-fluorenone, 5-p-ditolylaminobenzylidene-5H-diben/[a,d]cycloheptene, etc. Styryl compounds, 2-(p-diethylaminostyryl)-6-dinithylaminobenzoxazole, 2-(p-diethylaminophenyl)-4-(p-
Oxazole compounds such as dimethylaminophenyl)-5-(2-chlorophenyl)oxazole, 2-(p
thiazole compounds such as -diethylaminostyryl)-6-ethylaminobenzothiazole, triarylmethane compounds such as bis(4-jethylamino-2-methylphenyl)-phenylmethane, 1,1-bis(4
-N,N-diethylamino-2-methylphenyl)hebutane, polyarylalkanes such as 1,1,2.2tetrakis(4-N,N-dimethylamine-2-methylphenyl)ethane, triphenylamine, Examples include poly-N-vinylcarbazole, polyvinylpyrene, polyvinylanthracene, polyvinylacridine, poly-9-vinylanthracene, pyrene-formaldehyde resin, and ethylcarbazole 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 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. Examples of resins that can be used as binders include acrylic resin,
Insulating resins such as polyarylate, polyester, polycarbonate polystyrene, acrylonitrile-styrene copolymer, acrylonitrile-butadiene copolymer, polyvinyl butyral, polyvinyl formal, polysulfone, polyacrylamide, polyamide, chlorinated rubber, or poly-N-vinylcarbazole, polyvinylanthracene , organic photoconductive polymers such as polyvinylpyrene, and the like.

Since the charge transport layer has a limit in its ability to transport charge carriers, it cannot be made thicker than necessary. Generally it is 5 to 40 microns, but the preferred range is 10 to 40 microns.
It is 25 microns. 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, the support itself has conductivity, such as aluminum, aluminum alloy, copper, zinc, stainless steel,
vanadium, molybdenum, chromium, titanium, nickel,
Indium, gold, platinum, etc. can be used, and other materials include plastic 7, which has a layer formed by vacuum deposition of aluminum, aluminum alloy, indium oxide, tin oxide, indium oxide-tin oxide alloy, etc. conductive particles (e.g. carbon black, silver particles, etc.) can be applied onto the plastic with a suitable/hinder. coated support,
A support made of plastic or paper impregnated with conductive particles, a plastic containing 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 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 undercoat layer is 0.1 to 5 microns, preferably 0.1 to 5 microns.
5 to 3 microns is suitable.

When using an electrophotographic 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 in the exposed area are injected into the charge transport layer, and then reach the surface and neutralize the positive charge, causing a decrease in surface potential and a gap between the unexposed area and the exposed area. Electrostatic contrast occurs.

Shizuka Tr created in this way! , a visible image is obtained by developing the latent image with a negatively charged toner. This can be directly fixed, or the toner image can be transferred to paper or plastic film, 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, it is necessary to charge the surface of the charge transport layer negatively, 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 which it reaches the surface and neutralizes the negative charges, causing attenuation of the surface potential and creating an electrostatic contrast between it and the unexposed area.

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

Further, as the electrophotographic photoreceptor of the present invention, there can be mentioned an electrophotographic photoreceptor containing the above-mentioned azo pigment and a charge transporting substance in the same layer.

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 can be prepared by dispersing the above-mentioned azo pigment and 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 type of pigment selected from azo pigments having an organic residue represented by the general formula (1), and if necessary, pigments with different light absorptions may be combined. For the purpose of increasing the sensitivity of a photoreceptor or obtaining a panchromatic photoreceptor, two or more types of azo pigments having an organic residue represented by general formula (1) may be combined, or known dyes, It is also possible to use them in combination with charge-generating substances selected from 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 and CRT printers.

[Example] Examples 1 to 12 Ammonia aqueous solution of casein (casein 1
1.2g, 28% ammonia water 1g, water 222 mJl
) was coated with a Mayer bar so that the film thickness after drying was 1.0 microns and dried.

Next, 5 g of the exemplary pigment (2-1) was added to a solution prepared by dissolving 2 g of butyral resin (degree of butyralization: 63 mol %) in 95 mJl of tetrahydrofuran, 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 0.4 microns, and then dried. 5 g of hydrazone compound and 5 g of polymethyl methacrylate (number average molecular weight 100,000) benzene 7
The electrophotographic photoreceptor of Example 1 was prepared by dissolving the solution in 0 mal and applying this solution onto the charge generation layer using a Mayer bar so that the film thickness after drying would be 19 microns, and drying to form a charge transport layer. Created.

Examples 2-
An electrophotographic photoreceptor corresponding to No. 12 was prepared.

The electrophotographic photoreceptor thus prepared was tested using an electrostatic copying paper tester (Kawaguchi Denki Model SP-428).
The sample was corona-charged statically at -5.5 KV using a 100-degree battery, held in a dark place for 1 second, and then exposed to light at an illuminance of 5 lux to examine its charging characteristics.

The charging characteristics include the surface potential (Vo) and the amount of light exposure (El) required to attenuate the potential to 172 when dark decaying for 1 second
/2) was measured. Show the results.

-6 V -V El/2 lux s
ec engineering (2-1) 7o0 2.82
(2-2) 705 2.23 (2-5
) 705 2.34 (2-7) 70
0 2.55 (2-8) 705 2
．． 16 (2-11) 700 3.47
(2-12) 700 3.28 (2-18
) 710 2.39 (2-19) 71
0 2.110 (2-22) 700
2.211 (2-23) 705 2.61
2 (3-1) 700 3.5 Comparative example 1~
3 A photoreceptor was prepared in exactly the same manner as in Example 1.2.3, except that the azo pigment used in Example 1.2.3 was replaced with an azo pigment having the following structural formula, and evaluated in the same manner. Show the results.

(Comparative Example 1) vo knee 690V El/2: 9.7! Lux, 5 ec (Comparative Example 2) El/2 near, 3 sentences ux, 5 ec (Comparative Example 3) vo knee 700V El/2 near, 51 ux, see Comparative Examples 4 to 5 Also, Examples 8.9 and 10. A photoreceptor was prepared in exactly the same manner as in the previous example except that the following azo pigment was used in place of azo pigment No. 11, and it was evaluated in the same manner. Show the results.

(Comparative Example 4) Vony 691V El/2: 11, IJlux, 5ee (Comparative Example 5
) El/2: 10.2JLux, sec As is clear from the above results, it can be seen that all electrophotographic photoreceptors using the azo pigment specified in the present invention have excellent sensitivity.

Examples 13 to 14 Each electrophotographic photoreceptor prepared in Example 10.12 was
The 0 nm semiconductor laser and its scanning unit were replaced with a tungsten light source, and corona charging was performed statically at -5.5 KV using an electrostatic copying paper tester (a modified model of Model IsP-428 manufactured by Kawaguchi Electric). After being held in a dark place for 1 second, it was exposed to laser light and the charging characteristics were examined.

The charging characteristics include the surface potential (vO) and the amount of light exposure (E11) required to attenuate the potential to 115 when dark decayed for 1 second.
5) was measured. Show the results.

-/%' V -V E115 J/c
myu13 (2-22) 710 2.71
4 (3-1) 705 2.2 From the above results, it is recognized that all of the electrophotographic photoreceptors of the present invention have excellent sensitivity to laser light.

Examples 15 to 20 Using the electrophotographic photoreceptors prepared in Examples 1, 2, 3, 8, 9, and 10, fluctuations in bright area potential and dark area potential during repeated use were measured.

In the measurement method, a 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.

Using this copier, the initial bright area potential (VL) and dark area potential (Vo) were set to -200V and -700V, respectively, and the bright area potential (VL) after being used 5,000 times.
) and dark potential (Vo) were measured.

Comparative Examples 6 to 10 The electrophotographic photoreceptors prepared in Comparative Examples 1 to 5 were used in Examples 15 to 10.
Potential fluctuations during repeated use were measured in the same manner as in No. 20. Show the results.

From the above results, it can be seen that the electrophotographic photoreceptor of the present invention has excellent characteristics with less potential fluctuation when used with edge reversal.

Example 21 5 g of 2,4,7-dolinitro-9-fluorenone and poly-4,4'-dioxydiphenyl-2,2-propane carbonate (molecular weight: 300,000) were placed on the charge generation layer prepared in Example 1. The coating amount after drying the coating solution prepared by dissolving 5g in 70mjL of tetrahydrofuran is 10g7m2
It was applied and dried.

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.

V□: +720V.

El/2: 3.9JLux, see Example 22 A 0.5 micron thick polyvinyl alcohol film was formed on the aluminum surface of an aluminum vapor-deposited polyethylene terephthalate film.

Next, the dispersion of the disazo pigment used in Example 8 was placed on the polyvinyl alcohol layer formed previously so that the film thickness after drying was 0.
．． It was coated with a Mayer bar to a thickness of 5 microns and dried to form a charge generation layer.

A solution prepared by dissolving 5g of polyarylate (condensation polymer of bisphenol A and terephthalic acid-inphthalic acid) in 70mM of tetrahydrofuran was applied onto the charge generation layer so that the dry film thickness was 18 microns, and dried. A charge transport layer was formed.

The charging characteristics and durability characteristics of the electrophotographic photoreceptor thus prepared were evaluated in the same manner as in Example 1 and Example 16.
It was fixed at 1. Show the results.

vow-685V, El/2: 3. IJLux, sec durability characteristics Initial Vo knee 700V, VL knee 200V After 5,000 sheets durability VD knee 710V, VL knee 215V [Effects of the invention] The electrophotographic photoreceptor of the present invention uses a specific azo pigment in the photosensitive layer. As a result, carrier generation efficiency and/or carrier transport efficiency within the photosensitive layer containing the azo pigment are improved, and the electrophotographic photoreceptor has excellent sensitivity and potential stability during long-term use.

Claims (1)

[Claims] 1. An organic residue represented by the following general formula (I) on a conductive support is a substituted or unsubstituted aromatic hydrocarbon group or aromatic which may be bonded via a bonding group. An electrophotographic photoreceptor comprising a photosensitive layer containing an azo pigment having a structure bonded to a group heterocyclic group. ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (I) In the formula, R_1 represents an aromatic hydrocarbon group or an aromatic heterocyclic group which may have a substituent. 2. The electrophotographic photoreceptor according to claim 1, wherein the azo pigment is an azo pigment represented by the following general formula (II). ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (II) In the formula, Ar represents a substituted or unsubstituted aromatic hydrocarbon group or aromatic heterocyclic group which may be bonded via a bonding group, and n is is an integer of 1, 2, 3 or 4, and
X and R_1 have the same meanings as in general formula (I). 3. The azo pigment contains at least one organic residue selected from the organic residues represented by the general formula (I) and at least one organic residue represented by the following general formula (III) that is different from the selected organic residues. 2. The azo pigment according to claim 1, wherein the azo pigment has a structure in which one of the pigments is bonded to a substituted or unsubstituted aromatic hydrocarbon group or an aromatic heterocyclic group which may be bonded via a bonding group in the same molecule. Electrophotographic photoreceptor. ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (III) In the formula, Cp represents a coupler residue having a phenolic hydroxyl group.