JPH0253069A - electrophotographic photoreceptor - Google Patents

Abstract

PURPOSE:To provide a practicable high sensitivity characteristics and stable potential characteristic at the time of repetitive use by incorporating a specific residual coupler group to at least one of Cp in an azo pigment. CONSTITUTION:The residual coupler group expressed by formula II is incorporated to at least one of the Cp in formula I for the photosensitive layer contg. the azo pigment expressed by formula I. In formula I, Ar denotes an arom. hydrocarbon group or arom. heterocycle which may be bonded via a bond group; (n) denotes 1-4 integer. In formula II, A denotes an arom. hydrocarbon or the divalent group of the arom. heterocycle contg. a nitrogen atom in the ring. Either or both of the carrier generating efficiency or carrier transfer efficiency in the photosensitive layer contg. the azo pigment are improved in this way and the electrophotographic sensitive body having the excellent sensitivity and the potential stability at the time of durable use is obtd.

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 an azo pigment having a coupler component 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-diethylami/phenyl)-1,3,4 -Those using low-molecular organic photoconductive substances such as oxadiazole, and those in which such organic photoconductive substances are combined with 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.

Many pigments have been proposed for use in organic electrophotographic photoreceptors, but azo pigments in particular have been widely studied because pigments with various properties can be synthesized by combining amine components and coupler components. However, there are problems with sensitivity and potential stability when using edge reversing, and only a few materials are in practical use.

Coupler components used in such azo pigments include naphthol AS couplers described in JP-A No. 47-37543, benzcarbazole couplers described in JP-A-58-122967, etc. Naphthalimide couplers described in JP-A No. 54-79632, perinone couplers described in JP-A-57-176055, and the like are already known.

As a result of repeated research to solve the above problems, the inventor has found that
It has been found that an electrophotographic photoreceptor containing an azo pigment using a specific coupler described below has practical sensitivity and stable potential characteristics.

[Problem B 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 having practical high sensitivity characteristics and stable potential characteristics during repeated use. It is to be.

[Means for Solving the Problems 5] The present invention provides an electrophotographic photoreceptor having a photosensitive layer containing an azo pigment represented by the following general formula (1) on a conductive support, in which Cp in the general formula (1) The electrophotographic photoreceptor is characterized in that at least one of the above is a coupler residue represented by the following general formula (2).

In the formula, Ar represents a substituted or unsubstituted aromatic hydrocarbon group or aromatic heterocyclic group which may be bonded via a bonding group, Cp represents a coupler residue having a phenolic hydroxyl group, and n represents 1.2.Indicates an integer of 3 or 4.

In the formula, A represents an aromatic hydrocarbon which may have a substituent or a divalent aromatic heterocyclic group containing a nitrogen atom in the ring.

Specifically, Ar includes aromatic hydrocarbon groups such as benzene, naphthalene fluorene, phenanthrene, and anthracempyrene, furan, thiophene, pyridine, indole, benzothiazole, carbazole, acridone, dibenzothiophine, benzoxazole, and benzotriazole oxa. Aromatic heterocyclic groups such as diazole and thiazole, and those in which the above aromatic rings are bonded directly or with an aromatic group or a non-aromatic group, such as triphenylamine, diphenylamine, N-methyldiphenylamine, biphenyl, Terphenyl, binaphthyl, fluorenone, phenanthrenequinone, anthraquinone, benzanthrone, diphenyloxadiazole, phenylbenzoxazole, diphenylmethane, diphenylsulfone, diphenyl ether, benzophenone, stilbene, distyrylbenzene, tetraphenyl-p-phenylenediamine, Examples include tetraphenylbenzidine.

The optional substituents of the aromatic hydrocarbon group or aromatic heterocyclic group that may be bonded via the above-mentioned bonding group include alkyl groups such as methyl, ethyl, propyl, and butyl, and alkyl groups such as methoxy and ethoxy. group, dimethylamino,
Examples include dialkylamino groups such as diethylamino, halogen atoms such as fluorine, chlorine, and bromine, hydroxy groups, nitro groups, cyan groups, and halomethyl groups.

Specifically, A includes 0-phenylene, 1.2-naphthylene, 2.3-naphthylene, perinaphthylene, 1,
2-Anthrylene, 2,2'-biphenylene, 2.3-
Examples include groups such as pyridinediyl, 4.5-pyridinediyl, 6.7-indazolediyl, and 6.7-chiralediyl.

Substituents for the above groups include methyl, ethyl, propyl,
Alkyl groups such as butyl, alkoxy groups such as methoxy and ethoxy, halogen atoms such as fluorine, chlorine, and bromine,
Examples include a nitro group, a cyano group, and a halomethyl group.

Further, in Cp in general formula (1), preferred examples of coupler residues that may coexist other than the coupler residues represented by general formula (?) include the following general formulas (4) to (8).
) Coupler residues having the structure shown below are mentioned.

R.

In the above general formulas (4), (5), and (6), X is a naphthalene ring that is fused to a benzene ring and may have a substituent;
Residues necessary to form anthracene ring, carbazole ring, benzcarbazole ring, dibenzofuran ring, etc. are shown.

R,, R2 is a hydrogen atom, an alkyl group that may have a substituent, an aryl group, an aralkyl group, a heterocyclic group, or R,
, represents a cyclic amino group containing a nitrogen atom to which R2 is bonded,
R3 represents a hydrogen atom, an alkyl group, an aryl group, an aralkyl group, or a heterocyclic group which may have a substituent.

R4 is an alkyl group that may have a substituent, an aryl group,
Indicates an aralkyl group or a heterocyclic group.

Z represents an oxygen atom or a sulfur atom, and the symbol represents 0 or 1.

Y represents a divalent aromatic hydrocarbon group or a divalent heterocyclic group containing a nitrogen atom in the ring.

Specifically, 0-phenylene, 0-naphthylenebelinaphthylene, 1.2-antrylene, 3.4 pyrazolediyl, 2.3-pyridinediyl, 4.5-pyridinediyl,
Examples include groups such as 6,7-indazolediyl and 6,7-chiralindiyl.

Examples of the alkyl group in the above expression include groups such as methyl, ethyl, propyl, and butyl; examples of the aralkyl group include groups such as benzyl, phenethyl, and naphthylmethyl; and examples of the heterocyclic group include pyridyl, thienyl, furyl, Examples include groups such as thiazolyl, carbazolyl, dibenzofuryl, benzimidazolyl, benzothiazolyl,
Examples of the cyclic amine group containing a nitrogen atom in the ring include virol,
Examples include cyclic amino groups derived from viroline, pyrrolidine, pyrrolidone, indole-indoline, in-indole, cartazole, benzindole, imidazole, pyrazole, pyrazoline, oxazine, phenoxazine, benzocarbazole, and the like.

Examples of substituent groups include alkyl groups such as methyl, ethyl, and propyl; alkoxy groups such as methoxy and ethoxy;
Substituted amino groups such as diethylamino and dimethylamino 7,
Examples include halogen atoms such as fluorine, chlorine, and bromine, phenylcarbamoyl groups, nitro groups, cyano groups, and helomethyl groups such as trifluoromethyl.

The specific azo pigment of the present invention can be prepared by diazotizing the corresponding amine by a conventional method and coupling it with the coupler to form the coupler residue represented by the above general formula (2) in the presence of an alkali in an aqueous system, or by coupling it with a diazonium salt in an aqueous system. After converting into borofluoride or zinc chloride double salt, it is coupled with a coupler in an organic solvent such as N,N-dimethylformamide or dimethyl sulfoxide in the presence of a base such as sodium acetate, triethylamine, or triethanolamine. It can be easily synthesized by In addition, when synthesizing a disazo pigment in which a coupler residue other than the coupler residue represented by general formula (2) coexists in the molecule, the corresponding diamine is tetrazotized by a conventional method and isolated as the above-mentioned soluble salt. After that, 1 mole of the coupler to form the coupler residue represented by general formula (2) is coupled, and then another coupler 1 is coupled.
It is synthesized by cambling moles, or one of the 7-mino groups of the diamine is protected with an acetyl group, etc., and this is diazotized to couple the coupler that should form the coupler residue represented by general formula (2). Afterwards, the protecting group is hydrolyzed with hydrochloric acid or the like, this is again diazotized, and the compound can be synthesized by coupling with another type of coupler.

Trisazo pigments and tetrakisazo pigments in which a coupler other than the coupler that should form the coupler residue represented by general formula (2) coexists in the molecule are also synthesized in the same manner.

Further, the coupler to form the coupler residue represented by the general formula (2) can be obtained by a condensation reaction between a diamine represented by the following general formula (9) and a dicarboxylic acid anhydride represented by the following general formula (IO).

and may be used as a mixture.

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

Hereinafter, only the ArCp portion, which is a portion that changes in the basic type, will be described.

Basic type I Ar-N=N-Op Exemplary pigment (1-1) υ (A has the same meaning as in general formula (2)) At this time, the reactant is an isomer represented by the following general formulas (11) and (12) However, in the present invention, both isomers are used. -NsN-Cpz exemplary pigment (27
1) Cps, Cp2: O Exemplary N(2-2) CpL, Cp2: Exemplary pigment (2-3) υ Exemplary pigment (2-7) cpt, Cp2: Exemplary pigment (2-8) CpI, Cp2: Exemplary Pigment (2-9) Cpl Cp2: Exemplary Pigment (2-4) ÷CH-CHshaapt, Cp2: Exemplary Pigment (2-5) A r: +C N Cp1 Cp2 Two Same Exemplary Pigment (2-6) ) cpt, Cp2: pl Cp2: Exemplary pigment 1O) CpI, Cp2 Two exemplary pigments (2- Cpl, Cp2: Exemplary pigment (2- CpI, C20: Exemplary pigment (2-, 13) Cpl: 脣n Exemplary pigment Cpl: Cpl: Exemplary pigment A r knee@-CH-C)!-@- Cp1.: Basic type 3 H3 / Exemplary pigment (2- A r knee@)-CH-C)1 Cpl: Exemplary pigment A r: 1 CH-C) Isha-N Cp] Cpl-N-N-Ar N=N Cpl Exemplary pigment pt CF2, CF2: Exemplary pigment (-3-2) CpI CF2 p3 2 Same as above Exemplary pigment (4-1) CpI, CF2, CF2, C
A F2:Jn solution was obtained. In this liquid, 10.5g of sodium borofluoride
(0,096 mol) dissolved in 90 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.

Yield: 12.4 g, Yield: 86.2% Next, put DMFloomM into the beaker again. The azo pigment composed of general formula (1) and general formula (2) is not limited to the above example. do not have.

Pigment synthesis example (synthesis of exemplary pigment (2-6)) 300+n!
In a beaker, add 150 ml of water and 20 ml of concentrated hydrochloric acid (0.23
mole) and 2,5-bis(4′-aminophenyl)-1,
3,4-oxadiazole 8.1g (0,032 mol)
and cooled to 0°C, and added 4.5% sodium nitrite to it. s
g (0°067 mol) dissolved in 10 mJL of water,
It was dropped into the liquid over 10 minutes while keeping the liquid temperature below 5°C. After stirring for 15 minutes, carbon filtration was carried out and tetrazotization was performed. After cooling the liquid temperature to to'c, 9.0 g (0,020 mol) of the borofluoride salt obtained earlier was
and then 5.1 g of triethylamine (0.05
0 mol) was added dropwise over 5 minutes. After stirring for 2 hours, the precipitated pigment was collected by filtration, washed four times with DMF and three times with water, and then freeze-dried.

Yield 14.5g, yield 85.9%, melting point 300°C or higher (decomposition) Elemental analysis Calculated value (%) Actual value (%) C70.9
171,02 H3,103,14 N 16.54 16.68 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.

That is, in a specific example of the present invention, an electrophotographic photoreceptor can be prepared by dispersing the azo pigment in a suitable binder and forming a film on a conductive support.

In a preferred embodiment of the present invention, the photosensitive layer of the electrophotographic photoreceptor is functionally separated into a charge generation layer and a charge transport layer. A sexual coating can be applied.

The charge generating layer contains the aforementioned specific azo pigments which exhibit as much photoconductivity as possible in order to obtain sufficient absorbance;
In addition, in order for the generated charge carriers to be efficiently transported to the interface between the charge transport layer and the conductive support, the thickness of the thin film layer 1 is, for example, 5 gm or less, preferably 0.01 to 1 p.
A thin film layer having a thickness of Lm is desirable.

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

Polyarylates (bisphenol A and phthalic acid!Ii)
Examples include insulating resins such as polycarbonate, polyester, phenoxy resin, polyvinyl acetate, acrylic resin, polyacrylamide, polyamide, polyvinylpyridine, cellulose resin, urethane resin casein, polyvinyl alcohol, and polyvinylpyrrolidone. can. ! The resin content in the load-generating 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 alcohols such as methanol, ethanol, 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, trichloroethylene, etc., or aromatics such as benzene, toluene, xylene, ligroin, monochlorobenzene dichlorobenzene, etc. can be used.

Coating is done by dip coating method, spray coating method,
Spinner coating method, bead coach ink method, Meyer per coach ink method, fret coating method, roller coating method.

This can be carried out using a coating method such as 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 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.

Charge transporting substances include electron transporting substances and hole transporting substances, and electron transporting substances include chloranil, tetracyanoethylene, tetracyanoquinodimethane, 2,4,
5.7-tetranitro-9-fluorenone, 2,4,5
．． Examples include electron-withdrawing substances such as 7-titranitroxanthone and 2,4.8-trinidrothioxanthone, and polymerized versions of these electron-withdrawing substances.

Examples of hole-transporting substances include pyrene, N-ethylcarno<
Sol, N-methyl-N-phenylhydrazino-3-methylidene-9-ethylcarbazole N, N-diphenylhydrazino-3-methylidene-10-ditylphenothiazine, p-diethylaminobenzaldehyde-N,N-
Hydrazone compounds such as diphenylhydrazone, P-diethylbenzaldehyde-3-methylbenzthiazolinone-2-hydrazone, 2,5-bis(P-diethylaminophenyl)-1,3,4-oxadiazole, ■-
Phenyl-5-(p-diethylaminostyryl)-5-
(p-diethylaminophenyl)pyrazoline, 1-[
pyridyl (2)] -3-(p-diethylaminostyryl) -5-(p-') p-diethylaminophenyl)
Pyrazoline, 1-[pyridyl(2)]-5-(p-diethylaminostyryl)-4-methyl-3-(p-diethylaminophenyl)pyrazoline, l-phenyl-3-(
p-diethylaminostyryl)-4methyl-5-(p-
pyrazoline compounds such as diethylaminophenyl) pyrazoline and spiropyrazoline, α-phenyl-4-N
, N-diphenylaminostilbene, N-ethyl-5-
(α-phenylstyryl)carbazole, 9-dibenzylaminobenzylidene-9H-fluorenone, 5p-ditolylaminobenzylidene-3H-dibenzo[a,
d] Styryl compounds such as cycloheptene, 2-(
p-diethylaminostyryl)-6-dinithylaminobenzoxazole, 2-(p-diethylaminophenyl)-4-(p-dimethylaminophenyl)-5-(2-
Oxazole compounds such as chlorophenyl)oxazole, thiazole compounds such as 2-(p-diethylaminostyryl)-6-dinithylaminobenzothiazole, bis(4-diethylamino-2-methylphenyl)-
Triarylmethane compounds such as phenylmethane, 1
, 1-bis(4-N,N-diethylamino-2-methylphenyl)hebutane, 1.1,2.2tetrakis(4-
Polyarylalkanes such as N,N-dimethylamino-2-methylphenyl)ethane, triphenylamine,
Poly-N-vinylcarbazole, polyvinylpyrene, polyvinylanthracene, polyvinyl acridine poly-9
-vinyl anthracene, pyrene-formaldehyde resin, ethylcarbazole formaldehyde resin and the like. 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.

The charge transport layer cannot be made thicker than necessary because there is a limit to how much charge carriers can be transported.
It is pm. 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,
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 plastics having a layer formed by vacuum deposition of aluminum, aluminum alloy, indium oxide, tin oxide, indium oxide-tin oxide alloy, etc. For example, polyethylene, polypropylene polyvinyl chloride, polyethylene terephthalate acrylic resin,
Polyfluorinated ethylene, etc.) can be used, and conductive particles (e.g. carbon black, silver particles, etc.) can be used as a support made of plastic coated with a suitable binder, or as a support made of plastic or paper impregnated with conductive particles. Plastics having conductive polymers, 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, co-polymerized nylon alkoxymethylated nylon, etc.), polyurethane, gelatin, aluminum oxide, etc. .

The thickness of the undercoat layer is 0.1 to 5 p, m, preferably 0.1 to 5 m.
5 to 3 m is suitable.

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

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 specific 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 electrophotographic photoreceptor contains at least one type of pigment selected from azo pigments represented by general formulas (1) and (2), and its crystal form may be either amorphous or crystalline. .

In addition, if necessary, pigments of the above general formulas (1) and (2) 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 two or more types of azo pigments represented by the following, 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 23 A solution prepared by dissolving 5 g of methoxymethylated nylon (average molecular weight 32,000) and log alcohol-soluble copolymerized nylon (average molecular weight 29,000) in 95 g of methanol was placed on an aluminum substrate using a Mayer tube. Applied with a bar, film thickness after drying is 0.5pL
A subbing layer of m was provided.

Next, 5 g of the exemplified pigment (1-1) was dissolved in 95 mA of cyclohexanone with a butyral resin (butyralization degree: 63 mol%).
) was added to the dissolved solution and dispersed for 20 hours using a sand mill. This dispersion was applied onto the previously formed subbing layer using a Mayer bar so that the film thickness after drying was 0.3 μm, and dried to form a charge generation layer.

5g of hydrazone compound and polymethyl methacrylate (
Dissolve 5g of (number average molecular weight: 100,000) in 40ml of toluene, and apply this solution onto the charge generation layer so that the film thickness after drying is 207hm.
The electrophotographic photoreceptor of Example 1 was prepared by coating with a Mayer bar and drying to form a charge transport layer.

Examples 2-
An electrophotographic photoreceptor corresponding to No. 23 was prepared.

The electrophotographic photoreceptor thus prepared was tested using an electrostatic copying paper tester (Kawaguchi Denki Mari Model 5P-428).
) was statically charged with a corona at 13 KV, held in a dark place for 1 second, and then exposed to light at an illuminance of 10 lux to examine charging characteristics.

The charging characteristics include the surface potential (Vo) and the exposure ft (E
l/2) was measured. Show the results.

■ ■ ux , 4 , 3 , 5 , 0 , 2 , 4 , 6 , 5 , 9 , 0 , 3 , 8 , 6 , 1 , 7 , 6 , 3 , 7 20 (2-17) 700 1.8
21 (3-1) 680 1.
622 (3-2) 700 2
．． 523 (4-1) 695
2.4 Comparative Examples 1 and 2 A photoreceptor was prepared in the same manner as in Example 1, except that the azo pigment used in Example 1 was replaced with an azo pigment having the structural formula below. evaluated.

Show the results.

(Comparative Example 1) VO Knee 650V El/2: 4.3 Stand ux, 5ee (Comparative Example 2) V, Knee 600V El/2: 3.5J1ux, sec Results of Example 2 and Comparative Example 1.2 above It can be seen from the above that all the electrophotographic photoreceptors of the present invention have sufficient charging ability and excellent sensitivity.

Examples 24 to 28 Using the electrophotographic photoreceptors prepared in Examples 5, 7.9, and 11.20, 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 the cylinder is driven.

Using this copying machine, the initial dark area potential (Vo) and bright area potential (
The amount of variation in dark potential (ΔV
o) and the amount of variation in bright area potential (ΔVL) was measured. Show the results.

Note that a negative sign in the amount of change in potential represents a decrease in potential, and a positive sign represents an increase in potential.

24 5 -20 +202
5 7 +10 +202
6 9 -5 +152
7 11 +5 +252
8 20 -15 +25 Comparative Examples 3 and 4 The electrophotographic photoreceptors prepared in Comparative Examples 1 and 2 were used in Example 1.
In the same manner as in 3, potential fluctuations were measured when using the edge-turning method. Show the results.

3 1 -80 +5
04 2 -50 +6
5 From the above results, 1 it can be seen that the electrophotographic photoreceptor of the present invention has little potential fluctuation during repeated use.

Example 29 A polyvinyl alcohol film having a thickness of 0.5 pm was formed on the aluminum surface of an aluminum vapor-deposited polyethylene terephthalate film.

Next, the disazo pigment dispersion used in Example 12 was applied onto the previously formed polyvinyl alcohol layer using a Mayer bar so that the film thickness after drying was 0.31 Lm, and dried to form a charge generation layer. Formed.

5 g of styryl compound and 5 g of polyarylate (condensation polymer of bisphenol A and terephthalic acid-isophthalic acid)
A solution prepared by dissolving the above in 40 mJL of tetrahydrofuran was applied onto the charge generation layer so that the film thickness after drying was 20 lm, and dried 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 24. Show the results.

vo, -7l0V, El/2: 0.81ux, see ΔVQ: +5V ΔVL: +5V Example 30 Electrophotography in which the charge generation layer and charge transport layer of the electrophotographic photoreceptor prepared in Example 9 were applied in the reverse order. Create a photoreceptor,
The charging characteristics were evaluated in the same manner as in Example 1. However, the charging polarity was set to 10.

vo: +680V El/2: 1.81ux, sec Example 31 On the charge generation layer formed in Example 4, 5 g of 2,4.7-dolinitro-9-fluorenone and poly-4,4°-
Dioxydiphenyl-2,2-propane carbonate (
A solution obtained by dissolving 5 g of molecular weight 300,000 in 70 ml of chlorobenzene was coated and dried to give a film thickness of 15 gm after drying.

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

vo: +675V El/2: 4.21ux, sec Example 32 2.4.7) Rinitro 9-fluorenone 5g and poly-
A charge transfer complex compound was prepared by dissolving 5g of N-vinylcarbazole (number average molecular weight: 300,000) in 70ml of tetrahydrofuran.

This charge transfer complex compound and 1 g of the exemplary pigment (2-2) were added to and dispersed in a solution in which 5 g of polyester (trade name: Vylon, manufactured by Toyobo Co., Ltd.) was dissolved in 70 ml of tetrahydrofuran. This dispersion was prepared as in Example 1, applied onto the undercoat layer, and dried to form a photosensitive layer having a thickness of 16 μm.

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

v(,: +680V El/2: 3.91ux, sea [Effect of the invention] The electrophotographic photoreceptor of the present invention uses a specific 7zo pigment in the photosensitive layer, so that the inside of the photosensitive layer containing the azo pigment The electrophotographic photoreceptor has improved carrier generation efficiency and/or carrier transport efficiency, and has excellent sensitivity and potential stability during long-term use.

Claims (1)

[Claims] 1. In an electrophotographic photoreceptor having a photosensitive layer containing an azo pigment represented by the following general formula (1) on a conductive support, at least one of Cp in the general formula (1) is as follows: General formula (2
) An electrophotographic photoreceptor characterized by having a coupler residue represented by: ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (1) In the formula, Ar represents a substituted or unsubstituted aromatic hydrocarbon group or aromatic heterocyclic group that may be bonded via a bonding group, and Cp represents It represents a coupler residue having a phenolic hydroxyl group, and n represents an integer of 1, 2, 3 or 4. ▲There are numerical formulas, chemical formulas, tables, etc.▼ (2) In the formula, A represents an aromatic hydrocarbon which may have a substituent or a divalent group of an aromatic heterocycle containing a nitrogen atom in the ring. 2. The electrophotographic photoreceptor according to claim 1, wherein at least two layers, a charge generation layer and a charge transport layer containing an azo pigment represented by formulas (1) and (2), are provided on the conductive support. 3. An electrophotographic photoreceptor comprising a photosensitive layer containing an azo pigment represented by the following general formula (3) on a conductive support. ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (3) 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 A is It represents an aromatic hydrocarbon which may have a substituent or a divalent aromatic heterocyclic group containing a nitrogen atom in the ring, and n represents an integer of 1, 2, 3 or 4. 4. The electrophotographic photoreceptor according to claim 3, wherein at least two layers, a charge generation layer and a charge transport layer containing an azo pigment represented by formula (3), are provided on the conductive support.