JPH0350552A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To obtain the electrophotographic sensitive body having a practically high-sensitivity characteristic and the stable potential characteristic in repetitive use by forming a photosensitive layer of a specific azo pigment. CONSTITUTION:The photosensitive layer is so formed as to have the structure combined with the substd. or unsubstd. arom. hydrocarbon ring or arom. heterocyclic ring which may be combined with the residual org. group expressed by formula I via a bond group. In the formula I, X denotes the residual group necessary for forming the arom. hydrocarbon ring and the arom. heterocyclic ring by condensing with a benzene ring. The electrophotographic sensitive body having the practically high-sensitivity characteristic and the stable potential characteristic in repetitive use is obtd. in this way.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) 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. For example, organic photoconductive polymers such as polyN-vinylcarbazole and polyvinylanthracene, low-molecular organic photoconductors such as carbazole, anthracene, birazolines, oxadiazoles, hydrazones, and polyarylalkane, and phthalocyanine pigments; Organic pigments and dyes such as azo pigments, cyanine dyes, polycyclic quinone pigments, berylene pigments, indigo dyes, thioindigo dyes, and methine squaric acid dyes are known.

In particular, organic pigments and dyes with photoconductivity are easier to synthesize than inorganic pigments, and the variety of compounds that exhibit photoconductivity in an appropriate wavelength range has been expanded, making it possible to use a large number of photoconductive compounds. Conductive organic pigments and dyes have been proposed.

For example, US Pat. No. 4,123,270, US Pat. No. 42,476
No. 14, No. 4251613, No. 4251614, No. 425682 1, No. 4260672, No. 4268596, No. 4278747, No. 42
As disclosed in No. 93628, etc., electrophotographic photoreceptors are known that use an azo pigment exhibiting photoconductivity as a charge generation substance in a photosensitive layer that is functionally separated into a charge generation layer and a charge transport layer. ing.

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 sensitive wavelength range, it is actually inferior to inorganic photoreceptors in terms of sensitivity and durability. (Problems to be Solved by the Invention) Therefore, an object of the present invention is to provide a novel electrophotographic photoreceptor.

Another object of the present invention is to provide an electrophotographic photoreceptor having practical high sensitivity characteristics and stable potential characteristics during repeated use.

(Means for solving problems) The above objects are achieved by the present invention as described below.

That is, the present invention provides a conductive support having the general formula (I) CN l A substituted or unsubstituted aromatic hydrocarbon ring or an aromatic heterocycle in which the organic residue represented by This is an electrophotographic photoreceptor characterized by having a photosensitive layer containing an azo pigment having a structure bonded to a ring.

(Function) By forming the photosensitive layer from a specific azo pigment, an electrophotographic photoreceptor can be provided that has practical high sensitivity characteristics and stable potential characteristics during repeated use. (Preferred Embodiments) The present invention will be explained in more detail by citing the following two preferred embodiments.

Preferred examples of X in the above formula (1) of the azo pigment used in the present invention include a naphthalene ring, an anthracene ring, a carbazole ring, and a penzocarbazole ring, which may be fused with a benzene ring and have a substituent. , a dibenzocarbazole ring, a dibenzofuran ring, a penzonaphthofuran ring, a dibenzocarbazole ring, a diphenylene sulfite ring, and an organic residue necessary to form an aromatic hydrocarbon ring or an aromatic heterocycle.

The substituents that the aromatic hydrocarbon ring or aromatic heterocycle may have include alkyl groups such as methyl, ethyl, propyl, and butyl, alkoxy groups such as methoxy, ethoxy, and broboxy, dimethylamino, and diethylamino. Examples include substituted amino groups such as, halogen atoms such as fluorine, chlorine, and bromine, hydroxy groups, nitro groups, cyan groups, and halomethyl groups. Examples of substituted or unsubstituted aromatic hydrocarbon rings and aromatic heterocycles to which an organic residue represented by general formula (I) may be bonded via a bonding group include benzene, naphthalene, fluorene, phenanthrene, Hydrocarbon aromatic rings such as anthracene and birene; Heteroaromatic rings such as furan, thiophenone, pyridine, indole, penzothiazole, carbazole, acridone, dibenzothiophenone, penzoxazole, penzotriazole, oxadiazole, thiazole, etc.; or non-aromatic groups, such as triphenylamine, diphenylamine, N-methyldiphenylamine, biphenyl, terphenyl, binaphthyl, fluorenone, phenanthrenequinone, anthraquinone, benzanthrone, diphenyloxadi Azor,
Examples include phenylbenzoxazole, diphenylmethane, diphenylsulfone, diphenyl ether, penzophenone, stilbene, distyrylbenzene, tetraphenyl-p-phenylenediamine, and tetraphenylbenzidine. Examples of substituents that the aromatic hydrocarbon ring or aromatic heterocycle may have via the above-mentioned bonding group include methyl, ethyl,
Alkyl groups such as probyl and butyl, alkoxy groups such as methoxy and ethoxy, dialkylamino groups such as dimethylamino and diethylamino, halogen atoms such as fluorine, chlorine and bromine, hydroxyl groups, nitro groups, cyano groups, halomethyl groups, and the following general groups: Examples include substituted azo groups represented by the formula (III) -N=N-Cp (III). Cp in the above general formula (IO) represents a coupler residue having a phenolic hydroxyl group, and preferable examples include those having structures represented by the following general formulas (TV) to (XV).

CN/゛1X1R, No, I, X in the above general formula is a naphthalene ring, anthracene ring, carbazole ring, penzocarbazole ring, dibenzocarbazole ring, which may be fused with a benzene ring and have a substituent. Indicates an organic residue necessary to form an aromatic hydrocarbon ring or an aromatic heterocycle such as a dibenzofuran ring, a penzonaphthofuran ring, a fluorenone ring, or a diphenylene sulfite ring.

R and R represent a hydrogen atom, an alkyl group which may have a substituent, an aralkyl group, an aryl group, a heterocyclic group, or a cyclic amino group containing in the ring a nitrogen atom to which R and R4 are bonded.

R. and R. represents a hydrogen atom, an alkyl group, an aralkyl group, an aryl group, or a heterocyclic group which may have a substituent.

R represents an alkyl group, an aralkyl group, an aryl group, or a heterocyclic group which may have a substituent. Y. represents a divalent hydrocarbon ring group or a heterocyclic group which may have a substituent. Contains Y1=C=Y. For closing, etc. can be mentioned.

Y represents a Z-valent aromatic hydrocarbon ring group which may have a substituent, and examples include O-phenylene, O-naphthylene, berinaphthylene, 1,2-anthrylene, and 9,10-phenanthrylene. Y, represents a divalent aromatic hydrocarbon ring group which may have a substituent or a divalent heterocyclic group containing a nitrogen atom in the ring, and the divalent aromatic hydrocarbon ring group is 0 -phenylene, O-
Naphthylene, perinaphthylene, L,2-antrylene,
Examples include 9,1O-phenanthrylene group, and examples of divalent heterocyclic groups containing a nitrogen atom in the ring include 3,4-pyrazoldiyl group, 2,3-pyridinediyl group, 4,5
Examples include monopyrimidinediyl group, 6.7-indazolediyl group, 5.6-penzimidazolediyl group, and 6.7-quinolinediyl group.

B represents an oxygen atom, a sulfur atom, or a monosubstituted or unsubstituted imino group, and the substituent for N is an alkyl group, an aralkyl group, or an aryl group that may have a substituent.

Z represents an oxygen atom or a sulfur atom.

Examples of the alkyl group in the above expression include groups such as methyl, ethyl, proyl, butyl, and the like.

Examples of the 7ralkyl group include groups such as benzyl, phenethyl and naphthylmethyl.

Aryl groups include phenyl, diphenyl, naphthyl,
Examples include groups such as anthril. Heterocyclic groups include biridyl, chenyl, furyl, thiazolyl, carbazolyl,
Examples include groups such as dibenzofuryl, penzimidazolyl, and penzothiazolyl.

Examples of the flexible amino group containing a nitrogen atom in the ring include virol, viroline, virolidine, virolidone, indole, indoline, isoindole, carbazole, benzoindole, imidazole, virazole, pyrazoline, oxazine, phenoxazine, penzocarpazole, etc. Examples include cyclic amino groups derived from. The substituents in the above expressions include alkyl groups such as methyl, ethyl, and probyl; alkoxy groups such as methoxy and ethoxy; halogen atoms such as fluorine, chlorine, bromine, and iodine; alkylamino groups such as dimethylamino and diethylamino groups; A phenylcarbamoyl group, a nitro group, a cyano group, a halomethyl group such as a trifluoromethyl group, etc.

Representative examples of azo pigments having organic residues of the general formula (I) are listed below. (Left below) In the above formula, when n=1, l-19 @Moss◎ When n=2, NO2 CF. When n = 3 Z: = Y When n = 4 (blank below) The coupler component represented by the general formula ( The azo pigment used in the present invention is synthesized by dehydration condensation with malononitrile using a known method. After diazotization and coupling with the coupler synthesized above in the presence of an alkali, or once the diazonium salt of the corresponding amino compound is isolated in the form of a salt such as a borofluoride salt or a zinc chloride double salt, an appropriate A solvent, for example DMF (
It can be produced by coupling in an organic solvent such as N,N-dimethylformamide) or dimethyl sulfoxide in the presence of a base such as sodium acetate, pyridine, or triethylamine.

Among the azo pigments used in the present invention, in the case of disazo, trisazo, and tetrakisazo pigments, if one or more coupler components represented by general formula (XVI) are contained in the same molecule, other coupler components may be used. It doesn't matter if it contains. In this case, the synthesis method is general formula (X■) (CL(:ONHI −-Ar− (NH*l +
(
represents 2, 3 or 4) is diazotized, coupled with the coupler represented by the general formula (XVT), and then hydrolyzed with mineral acids such as hydrochloric acid to form CN l (Ar, m represents the same meaning as the general formula (X■),
has the same meaning as general formula (I)), diazotized again, and coupled with another coupler having a phenolic hydroxyl group. Alternatively, the general formula (
XrX)Ar-tNHal,l(XIX)(
(Ar has the same meaning as in general formula (n), and n represents an integer of 2, 3, or 4) is converted into a diazonium salt by a conventional method, and this is converted into a coupler represented by general formula (X■). and another coupler may be mixed and dissolved in a solution for coupling.

Next, a typical synthesis example of the azo pigment used in the present invention will be shown.

Synthesis Example 1 (Synthesis of the aforementioned exemplified azo pigment No. 2-1) In a 300 mI2 beaker, water Loomβ, concentrated hydrochloric acid 2
Add 4mI2 (0.27 mol) and add 0-dianicidi:/10. while cooling in an ice water bath. 0 g (0.(
141 mol) was added, stirred, and the temperature of the solution was brought to 3°C.
Next, sodium nitrite6. 0g (0.087mol) of ice 10mj! A solution dissolved in water was added dropwise over 10 minutes while controlling the liquid temperature to below 5°C, and after the dropwise addition was completed, the mixture was stirred for an additional 30 minutes at the same temperature. After adding carbon to the reaction solution and filtering it, 13.5 g (0.123 mol) of sodium borofluoride was added.
A solution prepared by dissolving the above in 20 mε of water was added dropwise, and the precipitated borofluoride salt was collected by filtration, washed with water, and dried under vacuum (yield: 13.6 g, yield: 75%). Next, put 1 g of DMF in the 2Q beaker,
10.57 g (0.048 mol) of CN l was dissolved in this, and the liquid temperature was lowered to 5.
10. Cool to ℃ and add the borofluoride salt obtained earlier. Og(0.02
3 mol) of triethylamine. 8
g (0.038 mol) was added dropwise over 10 minutes, then 2
Stir for hours. After filtering the reaction solution, it was washed S times with DMFIβ, replaced with acetone, and vacuum dried to obtain the desired azo pigment No. 2
- 1 was obtained (yield 17.4 g, yield 80% (borofluoride salt base)). C: 71.38% 71.35%H7
3.71% 3. 73%N:
15.86% 15.87% 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, the above-mentioned azo pigment can be used as a charge-generating substance in an electrophotographic photoreceptor in which the photosensitive layer is functionally separated into a charge-generating layer and a charge-transporting layer. The charge generation layer contains as much charge generation substance as possible in order to obtain sufficient absorbance, and is a thin film layer, for example, 5 um or less, preferably 0.01 to 0.01 μm, to shorten the range of the generated charge carriers. A thin film layer having a thickness of 1 um 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 are not deactivated by recombination or trapping, and the charge transport layer This is due to the need to inject the The charge generation layer can be formed by dispersing the azo pigment described above in a suitable binder and coating it on the substrate. 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 organic photoconductive polymers such as poly-N-vinylcarbazole, polyvinylanthracene, and polyvinylpyrene. Preferably polyvinyl butyral, polyvinylbenzal, polyarylate (condensation polymer of bisphenol A and phthalic acid, etc.), polycarbonate, polyester, phenoxy resin, polyvinyl acetate, acrylic resin, polyacrylamide resin, polyamide, polyvinylpyridine, cellulose type. Examples include insulating resins such as resin, urethane resin, epoxy resin, casein, polyvinyl alcohol, and polyvinylpyrrolidone. The resin contained in the N charge generation layer is suitably 80% by weight or less, preferably 40% by weight or less.

Coating methods include dip coating method, spray coating method, subinner coating method, bead coating method,
This can be done using coating methods such as Meyer bar coating, blade coating, roller coating, and curtain coating. Drying is
A preferred method is to dry to the touch at room temperature and then heat dry. Heat drying can be carried out at a temperature of 30 to 200°C for 5 minutes to 2 hours, either stationary or under ventilation. The solvent that dissolves these resins varies depending on the type of resin.
Further, it is preferable to select a material that does not dissolve the charge transport layer and subbing layer described below. Specific organic solvents include methanol, ethanol,
Alcohols such as isobrobyl alcohol, acetone,
Ketones such as methyl ethyl ketone and cyclohexanone,
Amides such as DMF%N,N-dimethylacetamide,
Sulfoxides such as dimethyl sulfoxide, ethers such as tetrahydrofuran, dioxane, and ethylene glycol monomethyl ether, esters such as methyl acetate and ethyl acetate, and fats such as chloroform, methylene chloride, dichloroethylene, carbon tetrachloride, and trichloroethylene. Group halogenated hydrocarbons or aromatics such as benzene, toluene, xylene, 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 charge carriers injected from the charge generation layer in the presence of an electric field and transporting these charge carriers to the surface. ing. At this time, the charge transport layer may be laminated on or below the charge generation layer. However, it is desirable that the charge transport layer be laminated on the charge generation layer. Since a photoconductor generally has the function of transporting charge carriers, a charge transport layer can be formed by this photoconductor. The substance that transports charge carriers in the charge transport layer (hereinafter simply referred to as charge transport substance) is preferably substantially insensitive to the wavelength range of electromagnetic waves to which the charge generation layer is sensitive. The term "electromagnetic waves" used herein includes the broad definition of "light rays" including gamma rays, X-rays, ultraviolet rays, visible light, near-infrared rays, infrared rays, far-infrared rays, etc. When the photosensitive wavelength range of the charge transport layer coincides with or overlaps that of the charge generation layer, charge carriers generated in both layers trap each other, resulting in a decrease in sensitivity.

Charge transporting substances include electron transporting substances and tag transporting substances, and electron transporting substances include chloranyl,
Promoanil, tetracyanoethylene, tetracyanoquinodimethane, 2,4,7-trinitro-9-fluorenone, 2,4,5,7-tetranitro-9-fluorenone, 2,4,7-trinitro-9-dicyanomethylenefluorenone , 2,4,5.7-tetranitroxanthone,
There are electron-withdrawing substances such as 2,4.8-}linitrothioxanthone, and polymerized products of these electron-withdrawing substances.

Examples of hole-transporting substances include birene, N-ethylcarbazole, N-isopropylcarbazole, N-methyl-N
-Phenylhydrazino-3-methylidene-9-ethylcarbazole, N,N-diphenylhydrazino-3-methylidene-9-ethylrubazole, N,N-diphenylhydrazino-3-methylidene-10-12-methylphenothiazine , N,N-diphenylhydrazino-3-methylidene-10-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, 1-(quinolyl (2)
)-3-(p-diethylaminostyryl)-5-(p-
diethylaminophenyl) birazoline, 1-(biridyl(2))-3-(p-diethylaminostyryl)-5-
(p-diethylaminophenyl)virazon, 1-(6
-Methoxybilidyl (2)) -3-(p-diethylaminostyryl)-5-(p-diethylaminophenyl)
Birazoline, l-(Biridyl(3))-3-(p-diethylaminostyryl)-5-(p-diethylaminophenyl)Birazoline, l-(Biridyl(2))-3-(p
-diethylaminostyryl)-5-(p-diethylaminophenyl)birazoline, 1-(bilidyl(2))-3
-(p-diethylaminostyryl)-4-methyl-5-
(p-diethylaminophenyl)birazoline, ]-(biridyl(2))-3-(α-methyl-p-jethylaminostyryl)-5-(p-diethylaminophenyl)
Birazoline, ■-Phenyl-3-(p-diethylaminostyryl)-4-methyl-5-(p-diethylaminophenyl)-Virazoline, 1-phenyl-3-(α-benzyl-p-diethylaminostyryl)-5-(p-diethylaminophenyl) birazolines such as enyl)pyrazoline and subirovirazoline, styryl such as α-pheny-4-N,N-diphenylaminostilbene, N-ethyl-3(α-phenylstyryl)carbazole, and 4-N,N-dibenzylamino-9-fluorenylidene. system compound, 2-C
P-diethylaminostyryl)-16-diethylaminobenzoxazole, 2-(p-diethylaminophenyl)-4-(p-dimethylaminophenyl)-5-
Oxazole compounds such as (2-chlorophenyl)oxazole, 2-(p-diethylaminostyryl)-6-
Thiazole compounds such as dietylaminobenzothiazole, bis(4-diethylamino-2-methylphenyl)
Triarylmethane compounds such as phenylmethane, 1.
1-bis(4-N,N-diethylamino-2-methylphenyl)hebutane, l,1,2,2-tetrakis(4-
Polyaryl alkanes such as N,N-dimethylamino-2-methylphenyl)ethane, triphenylamine, poly-N-vinylcarbazole, polyvinylpyrene, polyvinylanthracene, polyvinylacridine, poly-9
-vinyl anthracene, birene-formaldehyde resin, ethylcarbazole formaldehyde resin, etc. 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, polyarylate, polyester, polycarbonate, polystyrene, acrylonitrile-butadiene copolymer, acrylonitrile-butadiene copolymer, polyvinyl butyral, polyvinyl formal, polysulfone, polyacrylamide, polyamide, and chlorinated rubber. Examples include insulating resins and organic photoconductive polymers such as poly-N-vinyl rubazole, polyvinylanthracene, and polyvinylpyrene. The charge transport layer has a limit to its ability to transport charge carriers, so it cannot be made thicker than necessary. Generally it is 5 to 30 μm, but the preferred range is 8 to 2 μm.
It is 0um. 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 substrate having a conductive layer. As the substrate having the conductive layer, materials that are conductive themselves such as aluminum, aluminum alloy, copper, zinc, stainless steel, vanadium, molybdenum, chromium, titanium, nickel, indium, gold, and platinum can be used. In addition, there are plastics (e.g., polyethylene, polypropylene, polyvinyl chloride, polyethylene terephthalate, acrylic resin, polyfluorinated ethylene, etc.), conductive particles (e.g. carbon black, silver particles, etc.) coated on plastic with an appropriate binder, substrates made of plastic or paper impregnated with conductive particles, and conductive materials. Plastics having polymers, etc. can be used.

An undercoat layer having a barrier function and an adhesive function can also be provided between the conductive layer and the photosensitive layer. The subbing layer is made of casein, polyvinyl alcohol, nitrocellulose, ethylene-acrylic acid copolymer, polyamide (nylon 6,
It can be formed from nylon 66, nylon 6i0, copolymerized nylon, alkoxymethylated nylon, etc.), polyurethane, gelatin, aluminum oxide, etc. The thickness of the undercoat layer is O. 1 to 5 μm, preferably 0.5 to 3 μm
is appropriate.

When using a photoreceptor in which a conductive layer, a charge generation layer, and a charge transport layer are laminated in this order, and the charge transport material is an electron transport material, the surface of the charge transport layer must be positively charged, and exposure after charging is required. Then, in the exposed area, electrons generated in the charge generation layer are injected into the charge transport layer, and then reach the surface and neutralize the positive charges, causing attenuation of the surface potential and creating an electrostatic contrast with the unexposed area. A visible image can be obtained by developing the electrostatic latent image created in this way with negatively charged toner. This can be directly viewed, or the toner image can be transferred to paper, plastic film, etc. and then developed and fixed.

Also, static 1 on the photoreceptor! Another method is to transfer and develop the latent image onto an insulating layer of transfer paper and fix it. The type of developer, developing method, and fixing method may be any known one or any known method, 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. , which then reaches the surface and neutralizes the negative charges, causing a decrease in surface potential and an electrostatic contrast between it and the unexposed area. During development, it is necessary to use positively charged toner, as opposed to using an electron transporting substance. Another specific example of the present invention is an electrophotographic photoreceptor in which the azo pigment described above is contained in the same layer as a charge transport substance. At this time, in addition to the above-mentioned charge transport material, bolyN-
A charge transfer metal compound consisting of vinyl rubazole and trinitrofluorein can be used.

The electrophotographic photoreceptor of this example can be prepared by dispersing the aforementioned azo pigment and charge transfer complex compound in a polyester solution dissolved in tetrahydrofuran, and then forming a film thereon.

In any photoreceptor, the pigment used is of the general formula (I)
Contains at least 01 types of pigments selected from azo pigments having organic residues shown in the following. If necessary, pigments with different light absorptions may be used in combination to increase the sensitivity of the photoreceptor,
For the purpose of obtaining a bank chromatic photoreceptor, the general formula (I
) It is also possible to use a combination of two or more types of azo pigments having organic residues, or to use them in combination with a charge generating substance selected from known dyes and pigments. The electrophotographic photoreceptor of the present invention can be used not only for electrophotographic copying machines, but also for
It can also be widely used in electrophotographic applications such as laser printers and CRT printers. (Example) Next, the present invention will be explained in more detail with reference to Examples. Examples 1 to 14 An ammonia aqueous solution of casein (casein 1) was placed on an aluminum plate.
1.2g, 28% ammonia water 1g and water 222ml
2) was applied with a Mayer bar so that the film thickness after drying was 1.0 um and dried. Next, the above-mentioned exemplified azo pigment No.
2 (15 g) in 95 m of tetrahydrofuran (
? ．． butyral resin (butyralization degree 63 mol%) 2
g was added to the dissolved liquid and dispersed with 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 would be 0.4 μm, and dried to form a charge generation layer. Next, 5 g of a hydrazone compound having the structural formula and 5 g of polymethyl methacrylate resin (number average molecular weight 100,000) were added to 70 m of benzene! 2 and apply it on the charge generation layer so that the film thickness after drying is 19 μm.
A charge transport layer was formed by coating with a Mayer bar and drying. Also, azo pigment No. Photoreceptors corresponding to Examples 2 to 14 were prepared in the same manner using the exemplary pigments shown in Table 1 below in place of 2-1. The electrophotographic photoreceptor thus prepared was statically charged to -5.5 KV using an electrostatic copying paper tester Model SP-428 manufactured by Kawaguchi Denki, and after being held in a dark place for 1 second, Illuminance 5lux. The charging characteristics were investigated by exposing the sample to light. The charging characteristics include the surface potential (Vo) and the amount of exposure required to attenuate the potential to 1/2 when dark decaying for 1 second (
El/2) was measured. These results are shown in Table 1.

Comparative Examples 1 to 3 Photoreceptors were prepared in the same manner as in the previous example using azo pigments having the following structural formulas for the azo pigments of Examples 3, 10, and 11, and the results of the same evaluation were as follows. It is shown in Table 2.

■ A-N=N-@)-(;H=CI-@-CH=CI{-
@-N=N-8V. (-V) 705 E+. (lux. sec. 1 6. 4 V. (-V) 684 E+. (lux. sec. 1 7. 3 v. (-v) 7 0 1 E+/t (lux. sec. 8. 5 or more From Tables 1 and 2, the electrophotographic photoreceptor according to the present invention is as follows:
It can be seen that both have excellent sensitivity. Examples 15 to 22 The photoreceptors prepared in Examples 7 to 14 were prepared using an electrostatic copying paper tester (Kawaguchi Electric Co., Ltd.) by replacing the 780 ns+ semiconductor laser and its scanning unit with a tungsten light source.
j! The sample was corona-charged statically at -5.5 KV using a modified model SP-428 (manufactured by Miyazaki), held in a dark place for 1 second, and then exposed to laser light to examine the charging characteristics. The charging characteristics are the surface potential (vO) and the amount of light exposure required to attenuate the potential to 175 when dark decayed for 1 second (
El/5) was measured. The results are shown in Table 3.

Examples 23 to 27 Using the photoreceptors prepared in Examples 3, 5, 8, 10, and 11, fluctuations in bright area potential and dark area potential during repeated use were measured. As for the method, the photoreceptor was attached to the cylinder of an electrophotographic copying machine equipped with a -5 or 6 KV corona charger, an exposure optical system, a developer, a transfer charger, a static elimination exposure optical system, and a cleaner. Using this copying machine, the initial bright area potential (VL) and dark area potential (V.) were set to -200 V and -7, respectively.
Table 4 below shows the results of vL and V0 after repeated use 5,000 times with a setting of 0 0 V. was measured.

Comparative Examples 4 to 6 The potential fluctuations of the photoreceptors prepared in Comparative Examples 1 to 3 were measured during repeated use in the same manner as in Example 15. The results are shown in Table 5 below. (Left below) 5 From Tables 3 to 5 above,... It can be seen that the electrophotographic photoreceptor according to the present invention has excellent characteristics with little potential fluctuation during repeated use.

Example 28 On the charge generation layer prepared in Example 2, 5 g of 2,4,7-trinitro-9-fluorenone and poly-4,4°-dioxydiphenyl-2,2° propane carbonate (molecular weight 300,000) 5g to 70m of tetrahydrofuran
The coating amount after drying of the coating solution prepared by dissolving it in I2 is lo
The electrophotographic photoreceptor thus prepared was subjected to charge measurement in the same manner as in Example 1. At this time, the charge polarity was set to ten.
The results are shown below.

V,; +704 volts E+/z; 4. 61ux. sec. Example 29 A polyvinyl alcohol film with a thickness of 0.5 μm was formed on the aluminum surface of an aluminum vapor-deposited polyethylene terephthalate film. Next, the disazo pigment dispersion used in Example 1 was placed on the polyvinyl alcohol layer formed earlier so that the film thickness after drying was 0.
．． It was coated with a Mayer bar to a thickness of 5 um and dried to form a charge generation layer.

Next, 5 g of a stilbene compound with the structural formula and a polyarylate resin (condensation polymer of bisphenol A and terephthalic acid-isophthalic acid)
A solution obtained by dissolving 5 g of tetrahydrofuran at 70 m DEG C. was applied onto the charge generation layer so that the film thickness after drying would be 18 μm, and dried to form a charge transport layer.

The charging characteristics and durability characteristics of the photoreceptor thus prepared were measured by the same method as in Example 1. The results are shown below.

Charging characteristics: ■. (-Vl694 El/2 (lux.sec.) 2. 1 Durability characteristics; initial V. (-Vl 700V, f・-Vl 2
0 1 After 5.000 uses■. (-Vl680 V. (-Vl 2 1 0 Example 30 An ammonia aqueous solution of casein was applied onto a louum thick aluminum plate and dried to form a subbing layer with a film thickness of 0.5 μm.Next 2.2 .4.7-trinitro-9-fluorenone 5g
and poly N-vinylcarbazole (number average molecular weight 300
,000) was dissolved in 70 mj2 of tetrahydrofuran to form a charge transfer complex compound. This charge transfer complex compound and the above-mentioned exemplified azo pigment No. 2-25 (Ig),
5 g of polyester resin (Vylon, manufactured by Toyobo) was added to a solution dissolved in 70 ml of tetrahydrofuran and dispersed. This dispersion was applied onto the undercoat layer so that the film thickness after drying was 16 μm, and dried.

The charging characteristics of the photoreceptor thus prepared were measured using the same method as in the example. The results are shown below. However, the charging polarity was set to 10. ■. ; +710 volts El/l; 5. 51ux. sec. Example 3l A casein subbing layer was provided on an aluminum plate, and the charge transport layer and charge generation layer used in Example 7 were laminated in this order on top of this to prepare a photoreceptor. A photoreceptor was prepared in the same manner as in Example 1 except that the layer structure was different, and the charging characteristics were measured in the same manner. However, the charging polarity was set to 10. The results are shown below.

V. f+Vl;+694 volts E,/,;3,]. lux. sec. (Effects of the Invention) As is clear from the above, according to the present invention, by using a specific azo pigment having a coupler component with a dicyanovinyl group in the photosensitive layer, carrier generation efficiency in the photosensitive layer containing the azo pigment is improved. Alternatively, one or both of the carrier transport efficiency can be improved, and a photoreceptor with excellent sensitivity and potential stability during long-term use can be obtained, and furthermore, an excellent photoreceptor can be obtained that has sensitivity even in a long wavelength range.

Claims (5)

[Claims] (1) General formula (I) ▲Mathematical formula, chemical formula, table, etc. are present on the conductive support▼(I) (In the formula, X is an aromatic hydrocarbon that is fused to a benzene ring and may have a substituent. A substituted or unsubstituted aromatic hydrocarbon ring or an aromatic residue in which the organic residue represented by 1. A photoreceptor for electrophotography, comprising a photosensitive layer containing an azo pigment having a structure bonded to a group heterocycle. (2) The azo pigment has the general formula (II) ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (II) (In the formula, Ar is a substituted or unsubstituted aromatic hydrocarbon that may be bonded via a bonding group. represents a ring or aromatic heterocycle, X has the same meaning as in general formula (I), and n is 1
, an integer of 2, 3, or 4). (3) The azo pigment has at least one organic residue selected from the organic residues represented by the general formula (I) and a general formula (III) -N different from the selected organic residue. =N-Cp(III) (Cp in the formula represents a coupler residue having a phenolic hydroxyl group) and at least one organic residue represented by the following formula are bonded via a bonding group within the same molecule. 2. The electrophotographic photoreceptor according to claim 1, which is an azo pigment having a structure bonded to a substituted or unsubstituted aromatic hydrocarbon ring or aromatic heterocycle. (4) The electrophotographic photoreceptor according to claim 1, wherein the azo pigment is a mixture of at least one azo pigment according to claim 2 and at least one azo pigment according to claim 3. The electrophotographic photoreceptor according to claim 1, comprising at least three layers: (5) a conductive layer, a charge generation layer containing an azo pigment having an organic residue represented by general formula (I), and a charge transport layer.