JPH01204052A - 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 an amido compound and producing a coupler component, thus permitting practicable high sensitivity characteristics and stable potential characteristics at the time of repeated uses to be obtained.

Description

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

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

On the other hand, since the discovery that certain organic compounds exhibit photoconductivity, many organic photoconductors have been developed. , anthracene, pyrazolines, oxadiazoles, -hydrazones, low molecular organic photoconductors such as polyarylalkanes, phthalocyanine 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, U.S. Pat. No. 4,123,270, U.S. Pat.
47614 specification, 4251613 specification, 14251614 specification, 4256821 specification, 4260672 specification, 4268596
Specification of No. 4278747, No. 4293
628, an electrophotographic photoreceptor using an azo pigment exhibiting photoconductivity as a charge generation substance in a photosensitive layer functionally separated into a charge generation layer and a charge transport layer is known.

Electrophotographic photoreceptors using such organic photoconductors can be produced by coating by appropriately selecting a binder, making it possible to provide photoreceptors with extremely high productivity and low cost. Although this photoreceptor has the advantage of being able to freely control the 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). As a result of studies to solve the above-mentioned problems, the present inventors have found that it is extremely effective when a compound having an imide structure is used as a coupler.

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

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

゛...8.' In the formula, Indicates an aromatic hydrocarbon group or an aromatic heterocyclic group that may have a group.

The specific azo pigment in the present invention has the following general 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, X is an aromatic hydrocarbon such as naphthalene, anthracene, carbazole, benzcarbazole, dibenzocarbazole, dibenzofuran, benzonaphthofuran, fluorenone, diphenyl sulfide, etc., which may be condensed with a benzene ring and have a substituent. or a residue necessary to form an aromatic heterocyclic group, and R1 includes aromatic hydrocarbon groups such as benzene, naphthalene, fluorene, phenanthrene, anthracene, and pyrene, which may have substituents, and furan. , thiophene.

Examples include aromatic heterocyclic groups such as pyridine, benzothiazole, carbazole, dibenzothiophene, benzoxazole, benzotriazole, oxadiazole, and thiadiazole.

Substituents for X and R1 above include alkyl groups such as methyl, ethyl, and propyl, alkoxy groups such as methoxy and ethoxy, substituted amine groups such as diethylamino and dimethylamino, and halogens such as fluorine, chlorine, and bromine atoms. Examples thereof include atoms, nitro groups, cyan 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-phenyl diamine, 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-CP
(m) Substituted azo groups represented by the formula C (where Cp represents a coupler residue having a phenolic hydroxyl group) are exemplified.

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

", x"゛・X'"x"'-Xp'X'"-X'"x' R A hydrogen atom, an alkyl group that may have a substituent, an aralkyl group, an aryl group, a heterocyclic group, or a cyclic amino group containing a nitrogen atom to which R2 and R3 are bonded in the ring, R4 and R5 are hydrogen atoms, represents an alkyl group, aralkyl group, aryl group or heterocyclic group which may have a substituent, R6 represents an alkyl group, aralkyl group, aryl group or heterocyclic group which may have a substituent,
Yl represents a divalent aromatic hydrocarbon group or a heterocyclic group which may have a substituent, Y2 containing Yl represents a divalent aromatic hydrocarbon group which may have a substituent, and O -phenylene, 0-naphthylene, perinaphthylene, 1.2-antrylene, 9. Groups such as lO-phenanthrene are mentioned,
Y3 represents 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 0-phenylene, 0 -Naphthylene, perinaphthylene, 1,2-antrylene, 9.
Examples include groups such as 10-phenanthrene, and examples of the divalent heterocyclic group containing a nitrogen atom in the ring include 3,4-pyrazolediyl.

2.3-pyridinediyl, 4.5-pyrimidinediyl,
Examples include groups such as 6.7-indazolediyl, 5.6-benzimidazolediyl, and 6.7-chiralindiyl, Z represents an oxygen atom or a sulfur atom, and B represents an oxygen atom, a sulfur atom, or an N-substituted, non-substituted group. Indicates a substituted imino group,
As a substituent for N, an alkyl group which may have a substituent,
These are 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 virol and viroline. , pyrrolidine,
Pyrrolidone, indole, indoline, isoindole, carbazole, benzindole, imidazole, pyrazole, pyrazoline, oxazine, phenoxazine,
Examples include cyclic amino 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, alkylamino groups such as dimethylamino and diethylamino, phenylcarbamoyl groups, nitro groups, cyano groups, Examples include halomethyl groups such as trifluoromethyl.

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

Exemplary Pigment (1-1) o, N@-N-o-N-NA Exemplary Pigment (1-2) Exemplary Pigment (2-1) Exemplary Pigment (2-2) A-N Engineering N-@- cH-an-@-N-NA Exemplary Pigment (2-3) N A-N-N-@r-CH-C-@-N-NA Exemplary Pigment (2-4) Exemplary Pigment (2 -5) Exemplary pigment (2-6) Exemplary pigment (2-7) Exemplary pigment (2-8) Exemplary pigment (2-9) 2H5- Exemplary pigment (2-10) Exemplary pigment (2-11) Exemplary pigment Pigment (2-12) Exemplified pigment (,2-13) Exemplified pigment (2-14) Exemplified pigment (2-15) 0 Exemplified pigment (2-16) Exemplified pigment (2-17) Exemplified pigment (2- 18) Exemplary Pigment (2-19) Exemplary Pigment (2-20) 0M a-s-s-o-c-co combination
21) Exemplary Pigment (2-22) Exemplary Pigment (2-23) Exemplary Pigment (2-24) x Exemplary Pigment (3-1) Exemplary Pigment (3-2) A-N-N-αzN-NA Exemplary Pigment (3-3) Exemplary pigment (3-4) Exemplary pigment (3-5) Exemplary pigment (4-1) Exemplary pigment (4-2) The following general formula ( The coupler component represented by XI) can be easily synthesized using a known method using an acid halide compound represented by the general formula (XI) and a corresponding amide compound represented by the general formula (XV).

(Xllll) (XIV) CXv
> (In the formula, R1 and or once the diazonium salt of the corresponding amine compound is isolated in the form of a salt such as a borofluoride salt or a zinc chloride double salt, for example, N,N-dimethylformamide, dimethyl It can be produced by coupling in an organic solvent such as sulfoxide in the presence of a base such as sodium acetate, pyridine, or triethylamine.

In addition, among the above-mentioned specific azo pigments, in the case of disazo pigments, trisazo pigments, and tetrakis 7zo pigments, if one or more coupler components represented by general formula (XI) are contained in the same molecule, other It may also contain a coupler component.

The synthesis method in this case is to diazotize the amino compound represented by the general formula (XV), couple it with the coupler represented by the general formula (-), and then (CH)CONH)h, -Ar-(NHa)!
(X Vl ) (where Ar is the general formula (n
), m is an integer of l, 2 or 3, i+
(m is 2.3 to 4) Hydrolyzed with a mineral acid such as a salt to give -IHyu) -(X■) (In the formula, Ar has the same meaning as the general formula (n), n represents an integer of 2°3 or 4)
The amine 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 a monoazo compound, a corresponding azo pigment may be synthesized by sequentially adding couplers one component at a time for coupling.

Synthesis Example (Synthesis of Exemplary Pigment (2-1)) In a 500 m'i beaker, add 200 mJL of water and 48 g of concentrated hydrochloric acid.
mJ1 (0.54 mol) was added, and while cooling in an ice water bath, 20.0 g (0,082 mol) of 0-dianisidine was added and stirred. A solution of 12.0 g (0,174 mol) dissolved in 20 mJl of water was added dropwise over 10 minutes while keeping the liquid temperature below 5°C. After one drop was added, the mixture was stirred for another 30 minutes at the same temperature. 5 g of activated carbon was added to the reaction solution. Add +! ! After filtering, add 27.0 g (0,246 mol) of sodium borofluoride to 40 mJl of water.
The precipitated borofluoride salt was collected by filtration, washed with water, and then dried in vacuum.゛Yield: 29.4 g, Yield: 81% Next, put 200 mJl of DMF into a 5001 beaker, dissolve 5.83 g (0.02 mol) of 2-hydroxy-3-naphthoic acid benzoylamide therein, and bring the temperature of the solution to 5°C. Cool and add 4.24g (0,00
After dissolving 96 mol) of triethylamine, 1.94 mol of triethylamine
g (0,0192 mol) was added dropwise over 10 minutes, then 2
Stir for hours.

After filtering the reaction solution, N,N-dimethylformamide 2
After washing with 00 mJl four times and further washing with water three times, the pigment was dried by freeze-drying to obtain the target pigment.

Yield 6.81g, yield 83.6% (base for fluoroboration) Elemental analysis Calculated value (%) Actual value (%) C70.7
570,77 H4,274,23 N 9.90 9.96 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 404% 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,
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 solvent that dissolves these resins varies depending on the type of resin, and is preferably selected from those that do not dissolve the charge transport layer or undercoat layer described below.

Specific organic solvents include alcohols such as methanol, ethanol, and isopropyl alcohol, acetone,
Ketones such as methyl ethyl ketone and cyclohexanone, amides such as N,N-dimethylformamide and N,N-dimethylacetamide, sulfoxides such as dimethyl sulfoxide, tetrahydrofuran, dioxane,
Ethers such as ethylene glycol monomethyl ether, esters such as methyl acetate and ethyl acetate.

Aliphatic halogenated hydrocarbons such as chloroform, methylene chloride, dichloroethylene, carbon tetrachloride, trichloroethylene, etc., 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 and taking charge carriers injected from the charge generation layer in the presence of an electric field, and transporting these charge carriers to the surface. have.

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

However, it is preferable that the charge transport layer is formed as a vI layer on the charge generation layer.

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

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

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

Charge transporting substances include electron transporting substances and hole transporting substances, and electron transporting substances include chloranil, bromoanil, tetracyanoethylene, tetracyanoquinodimethane, 2,4.7-dolinitro-9-fluorenone, 2
,4,5.7-tetranitro-9-fluorenone,2,
4.7-dolinitro 9-dicyanomethylenefluorenone, 2.4,5.7-titranitroxanthone, 2.4
．． Examples include electron-withdrawing substances such as 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-ditylphenothiazine, N, N-diphenylhydrazino-3-methylidene-
10-Ethylphenoxazine, p-diethylaminobenzaldehyde-N, N-diphenylhydrazone, p-diethylaminobenzaldehyde-N-α-naphthyl-N
-Phenylhydrazone, p-pyrrolidinobenzaldehyde-N,N-diphenylhydrazone, 1,3.3-trimethylindolenine-ω-aldehyde-N,N-diphenylhydrazone, p-diethylbenzaldehyde-3
-Hydrazones such as methylbenzthiazolinone-2-hydrazone, 2,5-bis(p-diethylaminophenyl)-1,3,4-oxadiazole.

1-phenyl-3-(p-diethylaminostyryl)-
5-(p-diethylaminophenyl)pyrazoline, 1-
[Quinolyl(2)]-3-(p-diethylaminostyryl)-5-(p-diethylaminostyryl)-5-(p-diethylaminostyryl)-pyrazoline, 1-[pyridyl(2)]-3-(p-diethylaminostyryl)-5-(p- diethylaminophenyl) pyrazoline.

l-[6-medoxypyridyl(2)]-3-(p-diethylaminostyryl)-5-(p-diethylaminophenyl)pyrazoline, l-[pyridyl(3)]-3-(p
-diethylaminostyryl)-5-(p-diethylaminophenyl)pyrazoline, l-[lepidyl (2)]-3
-(p-diethylaminostyryl)-5-(p-diethylaminophenyl)pyrazoline, l-[pyridyl (2)
] -3-(p-diethylaminostyryl)-4-methyl-5-(p-diethylaminophenyl)pyrazoline,
1-[Pyridyl(2)]-3-(α-methyl-p-diethylaminostyryl)-5-(p-diethylaminophenyl)pyrazoline, ■-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-
Diphenylaminostilbene, N-ethyl-3-(α-
phenylstyryl) carbazole, 9-dibenzylaminobenzylidene-9H-fluorenone, 5-p-ditolylaminobenzylidene-5H-dibenzo [a, d]
Styryl compounds such as cycloheftene, 2-(p-diethylaminostyryl)-6-dinithylaminobenzoxazole, 2-(P-diethylaminophenyl)-4
-(p-dimethylaminophenyl)-5-(2-chlorophenyl)oxazole and other oxazole compounds,
Thiazole compounds such as 2-(p-diethylaminostyryl)-6-dinithylaminobenzothiazole, triarylmethane compounds such as bis(4-diethylamino-2-methylphenyl)-phenylmethane, 1.1-
Bis(4-N, N-diethylamino-2-methylphenyl)hebutane, 1,1,2.2tetrakis(4-N,
Polyarylalkanes such as N-dimethylamino-2-methylphenyl)ethane, triphenylamine, poly-N-vinylcarbazole, polyvinylpyrene, polyvinylanthracene, polyvinylacridine, poly-9-
Vinyl anthracene, pyrene-formaldehyde resin,
Examples include ethyl carbazole formaldehyde resin.

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

Further, these charge transport substances can be used alone or in combination of two or more.

When the charge transport material does not have film-forming properties, a film can be formed by selecting an appropriate binder. Examples of resins that can be used as binders include acrylic resin,
Insulating resins such as polyarylate, polyester, polycarbonate polystyrene, acrylonitrile-styrene copolymer, acrylonitrile-butadiene copolymer, polyvinyl butyral, polyvinyl formal, polysulfone, polyacrylamide, polyamide, chlorinated rubber, or poly-N-vinylcarbazole, polyvinylanthracene , organic photoconductive polymers such as polyvinylpyrene, and the like.

The charge transport layer has a limit in its ability to transport charge carriers, so it cannot be made thicker than necessary. Generally, the thickness is 5 to 40 microns, but the preferred range is 10 to 40 microns.
It is 25 microns. When forming the charge transport layer by coating, an appropriate coating method as described above can be used.

A photosensitive layer having such a laminated structure of a charge generation layer and a charge transport layer is provided on a conductive support. As the conductive support, the support itself has conductivity, such as aluminum, aluminum alloy, copper, zinc, stainless steel,
vanadium, molybdenum, chromium, titanium, nickel,
Indium, gold, platinum, etc. can be used, among others.

Plastics (e.g., polyethylene, polypropylene, polyvinyl chloride, polyethylene terephthalate, acrylic resin, polyethylene fluoride ) can be used, such as supports made of conductive particles (e.g. carbon black, silver particles, etc.) coated on plastic with a suitable binder, supports made of plastic or paper impregnated with conductive particles, or conductive polymers. It is possible to use plastics having the following characteristics.

A subbing layer having barrier and adhesive functions may also be provided between the conductive support and the photosensitive layer.

The subbing layer is casein, polyvinyl alcohol, nitrocellulose, ethylene-acrylic acid copolymer, polyamide (nylon 6, nylon 66, nylon 610, copolymerized nylon, alkoxymethylated nylon, etc.), polyurethane, and gelatin.

It can be formed from aluminum oxide, etc.

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

When using an electrophotographic photoreceptor in which a conductive support, a charge generation layer, and a charge transport layer are laminated in this order, and the charge transport material is an electron transport material, the surface of the charge transport layer must be positively charged. When exposed to light after being charged, electrons generated in the charge generation layer in the exposed area are injected into the charge transport layer, and then reach the surface and neutralize the positive charge, resulting in attenuation of one surface type and the gap between the exposed area and the unexposed 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 organic residues represented by the general formula (1) 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 would be 0.4 microns, and dried. 5g of benzene 7
The electrophotographic photoreceptor of Example 1 was prepared by dissolving this liquid in a 0.0 m solution and coating it on the charge generation layer using a Mayer bar so that the dry film thickness was 19 microns, and drying it to form a charge transport layer. It was created.

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

The electrophotographic photoreceptor thus prepared was statically charged with corona at -5.5 KV using an electrostatic copying paper tester (MOd 6-bun 5P-428 manufactured by Kawaguchi Electric Co., Ltd.), and then charged in a dark place for 1 second. After holding.

It was exposed to light at an illuminance of 5 lux and its charging characteristics were examined.

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

6. V −V El/2 lux 5e
c1 (2-1) 701 2.42
(2-2) 705 2.03 (2-5
) 704 2.14 (2-7) 69
8 1.75 (2-8) 710 1
．． 66 (2-11) 697 1.97
(2-12) 699 1.88 (2-18
) 702 2.19 (2-19) 70
9 4.110 (2-22) 697
4.611 (2-23) 701
2.212 (3-1) 694
1.6 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 Examples 1 and 2.3 was replaced with an azo pigment having the structural formula below. , similarly evaluated. Show the results.

(Comparative Example 1) VO Knee 690V E 1/2: 9, '71 uX, S
e G (Comparative Example 2) El/2: 7.3JLux, 5ec (Comparative Example 3) vo Knee 700V El/2 Near, 5RuX,! lee Comparative Examples 4 to 5 Photoreceptors were prepared in the same manner as in the previous example except that the following azo pigments were used in place of the azo pigments in Examples 8.9 and 10.11. evaluated. Show the results.

(Comparative Example 4) V□knee 691V El/2: 11, IJlux, 5ec (Comparative Example 5
) E l / 2: l 0, 2 JL
u X , S e C As is clear from the above results, all electrophotographic photoreceptors using the azo pigment specified in the present invention have excellent sensitivity.

Examples 13 to 14 Each electrophotographic photoreceptor prepared in Example 4.12 was
By replacing the nm semiconductor laser and its scanning unit with a tungsten light source, we used an electrostatic copying paper tester (a modified model of Kawaguchi Model 5P-428) to perform corona testing at -5.5 KV in a static manner. After being charged and held in a dark place for 1 second, it was exposed to laser light and the charging characteristics were examined.

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

'i<V −V
E115 J/cm”13 (2-
7) 698 2.414 (
3-1) 689 2.3 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, and 9, 10, fluctuations in bright area potential and dark area potential during repeated use were measured.

In the measurement method, a photoreceptor was attached to the cylinder of an electrophotographic copying machine equipped with a -5.6 KV corona charger, an exposure optical system, a developer, a transfer charger, a static elimination exposure optical system, and a cleaner.

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

Example Azo pigment Initial Vo -V VL -V 15 (2-t) 705 22
5 Comparative Examples 6-10 The electrophotographic photoreceptors prepared in Comparative Examples 1-5 were used in Examples 15-10.
Potential fluctuations during repeated use were measured in the same manner as in No. 20. Show the results.

Comparative Example Azo Pigment Initial VD -V VL -V 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 5 g in 70 ml of tetrahydrofuran is l Og /
It was coated to a thickness of m 2 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: +691V.

E 1/2: 4, 2 nu X, S
ec 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 mfL 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 680V.

El/2: 2.91ux, sec Durability characteristics Initial Vo knee 700V, VL knee 195V5, after 1000 yen, Vo knee 690V, VL knee 220V Example 23 An ammonia aqueous solution of casein (as described above) was placed on a 100 micron thick aluminum plate. ) was applied and dried to form a subbing layer with a thickness of 0.5 microns.

Next, 5 g of 2,4.7-dolinitro-9-fluorenone
A charge transfer complex compound was prepared by dissolving 5 g of poly-N-vinylcarbazole (number average molecular weight: 300,000) in 70 mL of tetrahydrofuran.

This charge transfer complex compound and 1 g of the exemplary pigment (2-21) were added to a solution in which 5 g of a polyester resin (Vylon, manufactured by Toyobo Co., Ltd.) was dissolved in 70 ml of tetrahydrofuran, and dispersed. This dispersion was coated onto the undercoat layer so that the film thickness after drying was 16 microns, and the charging characteristics of the prepared electrophotographic photoreceptor were measured in the same manner as in Example 1.

The results are shown below, however, the charging polarity was assumed to be 10.

VQ: +710V El/2: 4.9jLux, sec Example 24 A casein subbing layer was provided on an aluminum plate, and the charge transport layer and charge generation layer used in Example 4 were laminated in this order on top of this. An electrophotographic photoreceptor was prepared in the same manner as in Example 4, except for the structure, and the charging characteristics were measured in the same manner. However, the charging polarity was set to 10.

VO: +685V El/2: 3.9uux, sec [Effects of the Invention] The electrophotographic photoreceptor of the present invention uses a specific azo pigment in the photosensitive layer, thereby reducing carrier generation inside the photosensitive layer containing the azo pigment. The electrophotographic photoreceptor has improved efficiency, carrier transport efficiency, or both, and has excellent sensitivity and potential stability during long-term use.

Claims (1)

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