JPH01204051A - 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 hydrazine 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, hydrazones, polyaryl alkanes, etc., low-molecular organic photoconductors, yaphthalocyanine pigments, azo pigments, cyanine dyes, polycyclic quinone pigments, perylene pigments, 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, US Pat. No. 4,123,270.

Specification No. 4247614, Specification No. 4251613, Specification No. 4251814, Specification No. 425682
Specification No. 1, Specification No. 4260672, Specification No. 426
An azo pigment that exhibits photoconductivity as a charge-generating substance in a photosensitive layer that is functionally separated into a charge-generating layer and a charge-transporting layer, as disclosed in Japanese Patent No. 8596, Japanese Patent No. 4278747, Japanese Patent No. 4293628, etc. Electrophotographic photoreceptors using the same are 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 sensitive wavelength range, it has problems 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 a compound having the structure shown in formula (1) below is extremely effective when 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 an organic residue represented by the following formula (I) on a conductive support, which may be a substituted or unsubstituted aromatic residue which may be bonded 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 hydrocarbon group or an aromatic heterocyclic group.

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

The above specific azo pigment in the present invention has the following formula (II
) can be shown.

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 an integer of 1, 2.3 or 4. In addition,
X and R1 have the same meanings as in general formula (I).

Specifically, aromatic hydrocarbons such as naphthalene, anthracene, carbazole, benzcarbazole, dibenzocarbazole, dibenzofuran, benzonaphthofuran, fluorenone, and diphenyl sulfide, 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 dimethylami7, 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. , aromatic hydrocarbon groups such as phenanthrene, anthracene, pyrene, furan, thiophene, and pyridine.

Aromatic heterocyclic groups such as indole, benzothiazole, carbazole, acridone, dibenzothiophene, benzoxazole, benzotriazole, oxadiazole, thiadiazole, etc., and further bonded to the above aromatic groups directly or with aromatic or non-aromatic groups. 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. , hydroxy group, nitro group,
Cyano group, halomethyl group or general formula -N-N-Op
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.

general formula : , Yl.

In the above formula, X and R1 have the same meaning as in general formula (I), and R2 and R3 are a hydrogen atom, an alkyl group that may have a substituent, an aralkyl group, an aryl group, a heterocyclic group, or R2 and R3 represents a cyclic amine group containing a bonded nitrogen atom in the ring, R4 and R5 represent a hydrogen atom, an alkyl group that may have a substituent, an aralkyl group, an aryl group, or a heterocyclic group, and R6 represents a substituent Alkylno 1 (, which may have・CY, Y2 is a divalent aromatic hydrocarbon Ts which may have a substituent
Examples include groups such as o-phenylene, 0-naphthylene, perinaphthylene, 1,2-antrylene, and 9,10-phenanthrene, and Y3 is a divalent aromatic hydrocarbon group which may have a substituent. or a divalent heterocyclic group containing a nitrogen atom in the ring, and examples of the divalent aromatic hydrocarbon group include O-7 enylene, 0-+ phthylene, perinaphthylene, 1.2-antrylene, and 9.10-phenanthrene. Divalent heterocyclic groups containing a nitrogen atom in the ring include 3,4-pyrazolediyl, 2,3-pyridinediyl, 4,5-pyrimidinediyl, 6,7-indazolediyl, 5.6-benzimidazolediyl, 6
．． Examples include groups such as 7-chiralindiyl, Z represents an oxygen atom or a sulfur atom, B represents an oxygen atom, a sulfur atom, or an N-substituted or unsubstituted imino group; These groups include an optional alkyl group, an aralkyl group, and an aryl group.

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 the heterocyclic group include pyridyl, thienyl, furyl, thiazolyl, carbazolyl, dibenzofuryl, benzimidazolyl, and benzothiazolyl, and examples of the cyclic ami7 group containing a nitrogen atom in the ring include pyrrole and pyrroline. , pyrrolidine,
Pyrrolidone, indole, indoline, isoindole, carbazole, benzindole, imidazole, pyrazole, pyrazoline, oxazine, phenoxazine,
Examples include cyclic amide 7 groups derived from benzocarbazole and the like.

Examples of substituents in the above expressions include methyl and ethyl.

Alkyl groups such as propyl; alkoxy groups such as methoxy and ethoxy; halogen atoms such as fluorine, chlorine, bromine and iodine; fulkylamino groups such as dimethylamino and diethylamino; phenylcarbamoyl groups; nitro groups; cyano groups; Examples include halomethyl groups such as fluoromethyl.

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

Exemplary Pigment (1-1) OYN -@-N (c-N=N-A Exemplary Pigment (1-2) Exemplary Pigment (2-1) Exemplary Pigment (2-2) A -N -N -@ -c) I -CH-4Ko1-A Exemplary Pigment (2-3) N A -N -N-@-cH-c -@-N-NA Exemplary Pigment (2-4) Exemplary Pigment ( 2-6) A-N-N association N-@-N-NA Exemplary pigment (2-7) Exemplary pigment (2-8) Exemplary pigment (2-9) C, Hs- Exemplary pigment (2 -10) Exemplary pigment (2-11) Exemplary pigment (2-12) Exemplary pigment (2-13) Exemplary pigment (2-14) Exemplary pigment (2-15) CΩ Exemplary pigment (2-16) A-N- N-@-N-o-N-NA Exemplary pigment (2-17) Exemplary pigment (2-18) Exemplary pigment (2-19) Exemplary pigment (2-20) Exemplary pigment (2-21) Exemplary pigment Pigment (2-22) Exemplary pigment (2-23) A-N-N-@-N-@-N-N-A' Exemplary pigment (2-
24) HJ A-N-N-@voice-@? -N-N-A' Exemplary Pigment (3-
1) Exemplary pigment (3-2) Exemplary pigment (3-3) Exemplary pigment (4-1) Exemplary pigment (4-2) The following - used in the synthesis of the azo pigment used in the present invention
The coupler component represented by the formula (Xi) is obtained by reacting the corresponding acid halide compound represented by the formula (C'R) with hydrazine,
- after forming the corresponding acid hydrazide of formula (XV),
- Synthesized by reacting with an acid halide compound represented by formula (XVI).

(XI) ('R) (XV)
(XVI) o-c x ' (wherein R1 and or - the same meaning as in formula (I),
(xo represents a halogen atom) The specific azo pigment used in the present invention can be prepared by diazotizing the corresponding amino compound by a conventional method and coupling it with the coupler synthesized above in the presence of an alkali, or Once the diazonium salt is prepared in the form of a salt such as a borofluoride salt or a double salt of zinc chloride, it is dissolved in a base such as sodium acetate, pyridine, or triethylamine in an organic solvent such as N,N-dimethylformamide or dimethylsulfoside. It can be produced by coupling in the presence of.

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 formula (Xll) are contained in the same molecule, other couplers It may contain ingredients.

The synthesis method in this case is to diazotize the amino compound represented by the formula (X■), couple it with the coupler represented by the formula (XI), and then (CH3cONH)yx-Ar-(MHI)J (
X■) (In the formula, Ar has the same meaning as - formula (II), sentence 1
(m is an integer of 1, 2 or 3, and cross + m is 2.3 or 4) Hydrolyzed with ¥414 acids such as hydrochloric acid to obtain, diazotized again and combined with a coupler having another phenolic hydroxyl group. It may be synthesized by coupling, or Ar-
CNHJL)yz (X■) (In the formula, Ar has the same meaning as - formula (n), n indicates an integer of 2.3 or 4)
The amino compound shown is converted into a diazonium salt by a conventional method,
This may be synthesized by coupling in a solution in which the coupler represented by the general formula (XI) and another coupler are mixed and dissolved.

Alternatively, the first coupler component is first coupled,
After forming the heptanoazo 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)) In a 500mfL beaker, 200+nJl of water and 48% of concentrated hydrochloric acid
ml (0.54 mol), and while cooling in an ice water bath, 20.0 g (0,082 mol) of O-dianisidine was added and stirred, and the liquid temperature was adjusted to 0 to 3°C. A solution of 12.0 g (0,174 mol) dissolved in 20 mL of water was added dropwise over 10 minutes while keeping the temperature below 5°C. After the dropwise addition, the reaction solution was stirred for an additional 30 minutes at the same temperature. Activated carbon was added to the reaction solution. After adding 5 g and filtering, add 27.0 g (0,246 mol) of sodium borofluoride to 40 + nfL of water.
The precipitated borofluoride salt was collected by filtration, washed with water, and then dried in vacuum.

Yield 29.4g, yield 81% Next, add 200mJl of DMF to a 500mJl beaker.
After dissolving 13 g (0.02 mol) of triethylamine and cooling the liquid temperature to 5°C, dissolving 4.24 g (0.0096 mol) of the previously obtained borofluoride salt, 1.94 g of triethylamine (
0,0192 mo/l/) 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, and further washed 3 times with water. The target pigment was obtained by freeze-drying.

Yield 6.66g, yield 78.8% (borofluoride salt base) Elemental analysis Calculated value (%) Actual value (%) C68.1
968,54 H4,354,4O N 12.72 12.75 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. A thin film layer having a thickness of 0.01 to 1 micron is preferable.

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 generation layer can be formed by dispersing the above-mentioned specific azo pigment in a suitable binder and coating it on a conductive support.

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. Preferably polyvinyl butyral, polyvinyl benzal, polyarylate (condensation polymer of bisphenol A and phthalic acid, etc.), polycarbonate, polyester, phenoxy resin, polyvinyl acetate, acrylic resin,
Examples include insulating resins such as polyacrylamide, polyamide, polyvinylpyridine, cellulose resin, urethane resin, casein, polyvinyl alcohol, and polyvinylpyrrolidone. The resin contained in the charge generation layer is suitably 80% by weight or less, preferably 40% by weight or less.

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 methyl ether, esters such as methyl acetate and ethyl acetate, aliphatic halogenated hydrocarbons such as chloroform, methylene chloride, dichloroethylene, carbon tetrachloride, and trichloroethylene, or benzene, toluene, and xylene. Aromatics such as , ligroin, monochlorobenzene, and dichlorobenzene 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. 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 term "electromagnetic waves" as used herein includes a broad definition of light rays including gamma rays, X-rays, ultraviolet rays, visible light, near infrared rays, infrared rays, far infrared rays, and the like. .

When the photosensitive wavelength range of the charge transport layer coincides with or overlaps that of the charge generation layer, charge carriers generated in both layers trap each other, resulting in a decrease in sensitivity.

Charge-transporting substances include electron-transporting substances and hole-transporting substances, and electron-transporting substances include chloranil, pugmoanil, tetracyanoethylene, tetracyanoquinodimethane, and 2,4.7-)nitro- 9-Fluorenone, 2
,4,5.7-tetranitro-9-fluorenone,2,
4. ．． 7-dolinitro 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-ethylcarbazole, N,N-diphenylhydrazino-3-methylidene-10-ethylphenothiazine, N,N -diphenylhydrazino-3-methylidene-
10-Ethylphenoxazine, p-diethylaminobenzaldehyde-N, N-diphenylhydrazone, p-diethylaminobenzaldehyde-N-α-su2thyl-N
-Phenylhydrazone, p-pyrrolidinobenzaldehyde N, N-diphenylhydrazone, 1,3.3-)limethylindolenine-ω-aldehyde-N,N-diphenylhydrazone, p-diethylbenzaldehyde-3-
Hydrazones such as methylbenzthiazolinone-2-hydrazone, 2,5-bis(p-diethylaminophenyl)-1,3,4-oxadiazole, 1-phenyl-3
-(p-diethylaminostyryl)-5-(p-diethylaminophenyl)pyrazoline, 1-[quinolyl (2)
]-3-(p-diethylaminostyryl)-5-(p-
diethyl7minophenyl)pyrazoline, 1-[pyridyl(2)]-3-(p-diethylaminostyryl)-5-
(p-diethylaminophenyl)pyrazoline, l-[6
-Medoxybilidyl(2)]-3-(p-diethylaminostyryl)-5-(p-diethylaminophenyl)pyrazoline, l-[pyridyl(3)]-3-(p-diethylaminostyryl)-5-(p-diethylaminostyryl)-5-(p-diethylaminophenyl)pyrazoline, phenyl)pyrazoline, l-[lepidyl (2) co-3-(p
-diethylaminostyryl)-5-(p-diethylaminophenyl)pyrazoline, 1-[pyridyl(2)] -
3-(p-diethylaminostyryl)-4-methyl-5
-(p-diethylaminophenyl)pyrazoline, l-[
Pyridyl (2) 3-3-(α-Methyl-p-diethylaminostyryl)-5-(p-diethylaminophenyl)pyrazoline, l-phenyl-3-(p-diethylaminostyryl)-4-methyl-5-(p -diethylaminophenyl)pyrazoline, l-phenyl-3-(α-benzyl-p-diethylaminostyryl)-5-(p-diethylaminophenyl)pyrazoline, spiropyrazoline and other pyrazolines, α-phenyl-4-N, N-diphenyl Styryl-based compounds such as aminostilbene, N-ethyl-3-(α-phenylstyryl)carbazole, 9-dibenzylaminobenzylidene-9H-fluorenone, 5-p-ditolylaminobenzylidene-5H-dibenzo[a,d]cycloheptene Compound, 2-(p-diethylaminostyryl)-6-dinithylaminobenzoxazole, 2-(p-diethylaminophenyl)-4-(p
Oxazole compounds such as -dimethylaminophenyl)-5-(2-chlorophenyl)oxazole, 2-(
Thiazole compounds such as p-diethylaminostyryl)-6-dinithylaminobenzothiazole, bis(4-
Triarylmethane compounds such as diethylamino-2-methylphenyl)-phenylmethane, 1,1-bis(
Polyarylalkanes such as 4-N,N-diethylamino-2-methylphenyl)hebutane, 1,1,2.2tetrakis(4-N,N-dimethylamino-2-methylphenyl)ethane, triphenylamine , poly-N-vinylcarbazole, polyvinylpyrene, polyvinylanthracene, polyvinylacridine, poly-9-vinylanthracene, 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 has a limit in its ability to transport charge carriers, so it cannot be made thicker than necessary, typically from 5 to 40 microns.

The preferred range is 10-25 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 aluminum, aluminum alloy, indium oxide, tin oxide,
Plastics (e.g., polyethylene, polypropylene, polyvinyl chloride, polyethylene terephthalate, acrylic resin, polyethylene fluoride, etc.) having a layer formed by vacuum evaporation of indium oxide-tin oxide alloy, etc. can be used, and are electrically conductive. A support in which particles (for example, carbon black, silver particles, etc.) are coated on a plastic together with a suitable binder, a support in which plastic or paper is 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 undercoat layer is formed from casein, polyvinyl alcohol, nitrocellulose, ethylene-acrylic acid copolymer, polyamide (nylon 6, nylon 66, nylon 610, copolymerized nylon, alkoxymethylated nylon, etc.), polyurethane, gelatin, aluminum oxide, etc. can.

The thickness of the 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.

A visible image is obtained by developing the electrostatic latent image thus formed with a negatively charged toner. This can be directly fixed, or the toner image can be transferred to paper or plastic film, 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 the photoreceptor used or obtaining a panchromatic photoreceptor, two or more types of azo pigments having an organic residue represented by formula (1) above are combined, or known dyes and pigments are used. It is also possible to use it in combination with a charge generating substance selected from:

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 Electric Co., Ltd. Model SP-).
428) in a static manner at -5.5 KV, held in a dark place for 1 second, and then exposed to light at an illuminance of 5 lux to examine charging characteristics.

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

;'XV -V El/2 lux 5ee
1 (2-1) 700 3.32
(2-2) 710 3.23 (2-5)
700 3.54 (2-7) 705
2.95 (2-8) 695 2.
86 (2-11) 700 2.97 (
2-12) 700 2.58 (2-18)
705 2.89 (2-19) 7
05 2.610 (2-22) 7
00 2.911 (2-23) 6
90 3.312 (3-1)
700 2.9 Comparative Examples 1 to 3 Photoreceptors were 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 way. Show the results.

(Comparative example 1) v6 knee 690V El/2: 9.7 Jlux, 5ee (Comparative example 2) E 1/2: 7, 3 fLu X
, 5 e C (Comparative Example 3) vo knee 700V El/2 near, 5JLux, see Comparative Examples 4 to 5 In addition, the following azo pigments were used in place of the azo pigments in Examples 8.9 and 10.11. A photoreceptor was prepared in exactly the same manner as in the previous example and evaluated in the same manner. Show the results.

(Comparative Example 4) Vo knee 691V El/2: 11, flux, 5ea (Comparative Example 5) El/2: 10.2 Jlux, sec As is clear from the above results, the azo pigment specified in the present invention was used. It can be seen that all the electrophotographic photoreceptors have excellent sensitivity.

Examples 13 to 14 Each electrophotographic photoreceptor prepared in Example 4.12 was
The nm semiconductor laser and its scanning unit were replaced with a tungsten light source, and static corona charging was performed at -5.5 KV using an electrostatic copying paper tester (a modified model of Model 5P-428 manufactured by Kawaguchi Electric). After holding it 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 175 when dark decayed for 1 second.
5) was measured. Show the results.

-6V -V E115 J/Cmλ13
(2-7) 695 4.714 (3-
1) 700 5.5 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 12, 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) was set after repeated use 5,000 times.
) and dark potential (Vo) were measured.

1B (2-18) 705 205 Comparative Examples 6 to 1O The electrophotographic photoreceptors prepared in Comparative Examples 1 to 5 were prepared in Examples 15 to 1B.
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 little potential fluctuation during repeated use.

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.

vO: +650V, El/2: 7, 71uX, Se
C Example 22 A polyvinyl alcohol film having a thickness of 0.5 microns 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 5 g of polyarylate (condensation polymer of bisphenol A and terephthalic acid-isophthalic acid) in 70 mJl 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 measured in the same manner as in Examples 1 and 16. Show the results.

vo knee 690V, El/2: 3. IJlux, sec durability characteristics Initial Vo knee 700V, VL knee 200V after 5,000 sheets durability V D: -705V, V L: -215V[
Effects of the Invention] In the electrophotographic photoreceptor of the present invention, by using a specific azo pigment in the photosensitive layer, either or both of carrier generation efficiency and carrier transport efficiency within the photosensitive layer containing the azo pigment is improved. It is an electrophotographic photoreceptor with 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.