JPS63282745A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To obtain a photosensitive body superior in sensitivity and potential stability at the time of repeated uses and having sensitivity up to a long wavelength region by incorporating a specified azo pigment in a photosensitive layer. CONSTITUTION:The azo pigment contained in the photosensitive layer formed on a conductive substrate is an aromatic hydrocarbon ring or an aromatic hetero ring substituted by an organic group represented by the formula in which each of R1 and R2 is H, nitro, cyano, halogen, halomethyl, substituted amino, or optionally substituted alkyl, aralkyl, aryl, or a heterocyclic group, thus permitting the obtained photosensitive body to be improved in carrier generating efficiency and carrier transfer efficiency in the inside of the photosensitive layer, superior in sensitivity and photential stability at the time of repeated uses by the presence of trisazo pigment, and wide in spectral sensitivity up to a long wavelength region.

Description

[Detailed description of the invention] [#! 1. TECHNICAL FIELD The present invention relates to an electrophotographic photoreceptor, and more particularly, to an electrophotographic photoreceptor having a photosensitive layer containing a specific 7-zoomone-4.

[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 poly-N-vinyl cal/hetool, polyvinylanthracene, carbazole, anthracene, pyrazolines, oxadiazoles,
and low-molecular organic photoconductors such as dracins, arylalkanes, phthalocyanine pigments, azo pigments, cyanine pigments, polycyclic quinone pigments, perylene pigments, indigo dyes,
- Organic pigments and dyes such as thioindigo dyes and squaric acid methine dyes are known.

In particular, photoconductive organic pigments and dyes are easier to synthesize than inorganic materials, and the variety of compounds that exhibit photoconductivity in an appropriate wavelength range has 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. 4,247,614, US Pat. No. 4,251,613, US Pat.
Specification No. 21, Specification No. 4260672, Specification No. 42
Specification No. 68596, Specification No. 4278747,
As disclosed in the specification of the same No. 4293628, 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. There is.

An electrophotographic photoreceptor using such an organic photoconductor can be produced by coating by appropriately selecting a binder, so it is possible to provide an extremely highly productive and inexpensive photoreceptor.
Moreover, while this photoreceptor has the advantage of being able to freely control the sensitive wavelength range by selecting the organic pigment, it is actually inferior to inorganic photoreceptors in terms of sensitivity and durability.

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

[Means for Solving the Problems, Effects] The present invention provides a conductive support with a general formula (wherein R1 and R2 are hydrogen atoms, an alkyl group which may have a substituent, an aralkyl group, an aryl group, A heterocyclic group, a nitro group, a cyano group, a halogen atom, a halomethyl group, or a substituted amino group, which may be the same or different, and R1 and R2 may jointly have a substituent. An isophane group having a structure in which an organic residue represented by ) is bonded to a substituted or unsubstituted aromatic hydrocarbon ring or aromatic heterocycle which may be bonded via a bonding group. The photoreceptor is composed of a photoreceptor characterized in that it has a photosensitive layer containing 1.

To explain the organic residue represented by the above general formula (I) in detail, examples of the alkyl group represented by R1 and R2 include methyl, ethyl, propyl, butyl, etc., and examples of the aralkyl group include benzyl, Examples of the aryl 2q include phenyl, naphthyl, anthranyl, phenanthryl, etc., and examples of the heterocyclic group include pyridyl, quinolyl, benzoxazolyl, benzothiazoyl, benzimidazoyl, Examples include groups such as benzotriazoleyl, halogen atoms include fluorine atoms, chlorine atoms, bromine atoms, etc., and halomethyl groups include trifluoromethyl, chloromethyl, and the like.

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

Furthermore, the substituted amine groups represented by R1 and R2 include dimethylamino, diethylamino, diphenylamino, dibenzylamino, and cyclic amine groups such as pyrrolyl, pyrrolidinyl, piperidino, and morpholino.

Examples of the ring core which may have a substituent jointly formed by R and R2 include the following cores, and the substituents in the above expression include alkyl groups such as methyl, ethyl, and propyl;
Alkoxy groups such as methoxy and ethoxy, fluorine atoms,
It means a halogen atom such as a chlorine atom or a bromine atom, a nitro group, a cyano group, or a halomethyl group such as trifluoromethyl.

Examples of substituted or unsubstituted aromatic hydrocarbon rings and aromatic heterocycles to which the 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 pyrene, furan, thiophene, pyridine,
Heteroaromatic rings such as indole, benzothiazole, carbazole, acridone, dibenzothiophene, benzoxazole, benzotriazole, oxadiazole, thiadiazole, etc., and those in which the above aromatic rings are bonded directly or with an aromatic or non-aromatic group. , such as triphenylamine, diphenylamine, N-methyldiphenylamine, biphenyl, terphenyl, binaphthyl,
Fluorenone, phenanthrenequinone, anthraquinone, penzanthrone, diphenyloxadiazole, phenylbenzoxazole, diphenylmethane, diphenylsulfone, diphenyl ether, benzophenone, stilbene, distyrylbenzene, tetraphenyl-p-
Examples include fluorinated diamine and tetraphenylbenzidine.

Examples of substituents on the above rings include alkyl groups such as methyl, ethyl, propyl, and butyl; alkoxy groups such as methoxy and ethoxy; halogen atoms such as fluorine, chlorine, and bromine; and dialkylamino such as dimethylamino and diethylamino. group, hydroxy group, nitro group, cyano group, halomethyl group or general formula -N=N-Op
Examples include substituted azo groups represented by (m).

Cp represents a coupler residue having a phenolic hydroxyl group, and more specifically includes those having a structure represented by the following general formula.

general formula 'X p.

OHO) 1 In the above general formula, X is fused with a benzene ring to form a naphthalene ring which may have a substituent, an anthracene ring, a carbazole ring, a benzocarbazole ring, a dibenzofuran ring, a pencinnatofuran ring, a fluorenone ring * Indicates a residue necessary to form an aromatic hydrocarbon ring or an aromatic heterocycle, such as.

R1 and R2 have the same meaning as in the above general formula (I), R
3 and R4 are hydrogen atoms, alkyl groups that may have substituents, aralkyl groups, aryl groups, heterocyclic groups, or R
3. Indicates a cyclic amino group containing the nitrogen atom to which R4 is bonded in the ring.

R5 and R6 represent a hydrogen atom, an alkyl group which may have a substituent, an aralkyl group, an aryl group, or a heterocyclic group.

R7 represents an alkyl group, an aralkyl group, an aryl group, or a heterocyclic group which may have a substituent.

Yl represents a divalent hydrocarbon ring group or a heterocyclic group which may have a substituent.

Oh.

Examples include.

Y2 represents a divalent aromatic hydrocarbon ring group which may have a substituent, and examples thereof include O-phenylene, 0-naphthylene, perinaphthylene, 1,2-antrylene, and 9,10-phenanthrylene groups.

Y3 represents a divalent aromatic hydrocarbon ring group which may have a substituent or a divalent heterocyclic group containing a nitrogen atom in the ring,
As the divalent aromatic hydrocarbon ring group, O-7 enylene, O
-Naphthylene, perinaphthylene, 1,2-antrylene, 9,10-phenanthrylene groups, etc., and 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-
Examples include benzimidazolediyl and 6,7-chiralindiyl groups.

B represents an oxygen atom, a sulfur atom, or an N-substituted or unsubstituted imino group, and examples of the substituent for N include an alkyl group, an aralkyl group, and an aryl group that may have a W1 substituent.

Examples of the alkyl group in the above expression include groups such as methyl, ethylpropyl, and butyl; examples of the aralkyl group include groups such as benzyl, phenethyl, and naphthylmethyl; and examples of the 7-aryl group include phenyl, diphenyl, naphthyl, Examples include groups such as anthryl, heterocyclic groups include pyridyl, chenyl, furyl, thiagrily, carbazolyl, dibenzofuryl, benzimidazolyl, and benzothiazolyl, and examples of cyclic amide groups containing a nitrogen atom in the ring include pyrrole. , pyrroline, pyrrolidine, pyrrolidone, indole, indoline, isoindole,
Examples include cyclic amino groups derived from carbazole, benzoindole, imidazole, pyrazole, pyrazoline, oxazine, phenoxazine, benzocarbazole, and the like.

The substituents in the above expressions are alkyl groups such as methyl, ethyl, and propyl; flukoxy groups such as methoxy and ethoxy; halogen atoms such as fluorine, chlorine, bromine, and iodine; and flukylamino groups such as dimethylamino and diethylamino. , phenylcarbamoyl group, nitro group, cyano group, halomethyl group such as trifluoromethyl, etc.

Typical specific examples of the azo pigment used in the present invention are listed below.

[Sevenanoazo pigment] 8-A [Disazo pigment] (l 1) A-N-N-@-C) I-fll:H-@-0H-CH
-rffl Upper H3 CyuHs (28) HD "When one is an organic residue represented by general formula (m)" - Example d Upper - n A-N-N-o-N (tN-N-B H3 [Trisazo Pigment] 6 A The coupler component represented by the following general formula (x■) used in the present invention is obtained by cyclizing the alkoxyacenaphthene and butadiene derivative shown below (X■) by Dials-Alder reaction (X It can be synthesized by dehydrogenating the compound (2) and then dealkylating it with a Lewis acid such as boron tribromide or aluminum chloride-ethanethiol.

(xm) The coupler component obtained by the above synthesis method can be obtained as a mixture of isomers depending on the substituents, but any isomer can be used in the present invention.

The azo pigment used in the present invention can be prepared by diazotizing the corresponding amine compound by a conventional method and coupling it with the coupler component synthesized above in the presence of an alkali, or by converting the diazonium salt of the corresponding amino compound into a borofluoride salt or a chloride. Once isolated in the form of a salt such as a zinc double salt, it is coupled in a suitable solvent such as an organic solvent such as N,N-dimethylformamide or dimethyl sulfoxide in the presence of a base such as sodium acetate, pyridine or triethylamine. It can be synthesized by

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 the general formula (x■) are contained in the same molecule, other coupler components May contain.

In this case, the synthesis method is to diazotize the amino compound represented by the general formula (X
X
or 4) After coupling with the coupler component represented by general formula (XI), hydrolysis with mineral acids such as hydrochloric acid, diazotization again, and coupling with another coupler component having a phenolic hydroxyl group. Alternatively, an amino compound represented by the general formula (XX[) Ar-+MHz)y+
, (X
It can also be synthesized by coupling the coupler component represented by and another coupler component in a mixed solution.

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

Synthesis of Exemplary Pigment (26) 100 ml of water in a 300 ml beaker, Sti! acid 2
Add 5mM (0.27 mol), cool in an ice water bath, and add 9.2 g of N-ethyl-3,6-diamicrubazole.
(0,041 mol) was added thereto, and the liquid temperature was brought to 3°C while stirring.

Next, add 6.0 g (0,087 mol) of sodium nitrite to 10 ml of water.
Add the dissolved liquid dropwise over 10 minutes while controlling the liquid temperature to below 5°C, and then add another 3 minutes at a dynamic temperature after dropping.
Stirred for 0 minutes.

After adding carbon to the reaction solution and filtering it, a solution of 13.5 g (0.123 mol) of sodium borofluoride dissolved in 20 mjl of water was added dropwise, and the precipitated borofluoride salt was collected by filtration, washed with water, and then vacuum-dried.

Yield 11.2g, yield 64% Next, put D M F 350 m father into the beaker.

8 g (0,048 mol) of 2-hydroxy-9,8-dimethylfluoranthene 1f was dissolved in this, and the liquid temperature was adjusted to 5°C.
Cool the borofluoride obtained earlier! ! IO, Og (0
, 023 mol), then triethylamine 5.
8 g (0,058 mol) was added dropwise over 10 minutes, then 2
The time was right.

After filtering the reaction solution, N,N-dimethylformamide 3
The mixture was washed 5 times with 00m water, replaced with acetone, and dried under vacuum to obtain Exemplary Pigment (26), which is an azo pigment of [1]. Yield 13.4g Yield 78.3% (borofluoride salt base) Elemental analysis calculated value (%) Actual value (%) C80,5180,40 H5,815,88 N 9.39 9.36 The above azo pigment A coating having the above-mentioned composition exhibits photoconductivity and can be used as a photosensitive layer of an electrophotographic photoreceptor as described above.

In a preferred embodiment of the present invention, the above-mentioned Azoface 1 is applied to a charge generating substance in an electrophotographic photoreceptor in which the photosensitive layer of the photoreceptor is functionally separated into a charge generation layer and a charge transport layer. Can be done.

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 or less, in order to shorten the range of the generated heavy carriers.
Preferably, it is a thin 112 layer with a thickness of 0.01-1 g.

This means that most of the incident light is absorbed by the charge generation layer and generates a large number of charge carriers, and that the generated carriers must be injected into the charge transport layer without being deactivated by recombination or trapping. This is due to the fact that

The charge generation layer can be formed by dispersing the azo pigment in a suitable binder and coating it on the substrate. ? l! The binder that can be used when forming the load generation layer by coating can be selected from a wide range of insulating resins.
It can also be selected from organic photoconductive polymers such as poly-N-vinylcarbazole, polyvinylanthracene and polyvinylpyrene.

&'r t L, < is polyvinyl butyral, polyarylate (condensation polymer of bisphenol A and phthalic acid, etc.), polycarbonate, polyester, phenoxy resin, polyvinyl acetate, acrylic resin, polyacrylamide, polyamide, polyvinylpyridine, cellulose type Examples include insulating resins such as resin, polyurethane, epoxy 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.

The solvent that dissolves these resins varies depending on the type of resin, and is preferably selected from those that do not dissolve the charge transport layer and undercoat layer described below.

Specific organic solvents include methanol, ethanol,
Alcohols such as Impropatool, ketones such as acetone, methyl ethyl ketone, cyclohexanone, N
, amides such as N-dimethylformamide and 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, chloroform, methylene chloride, dichloroethylene, 4j! Aliphatic halogenated hydrocarbons such as carbon monocide and trichloroethylene, or aromatic hydrocarbons such as benzene, toluene, xylene, ligroin, monochlorobenzene and dichlorobenzene, etc. can be used.

Coating methods include dip coating, spray coating, spinner coating, bead coating, Meyer bar coating, blade coating,
This can be carried out using a coating method such as a roller coating method or a curtain call coating method.

For drying, it is preferable 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 a time in the range of 5 minutes to 2 hours, either stationary or under ventilation. .

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, this charge transport layer may be laminated on top of the charge generation layer, or may be laminated below it. However, it is not recommended that the charge transport layer be laminated on the charge generation layer. preferable.

What are photoconductors in general? Since it has the function of transporting It charge carriers, a charge transport layer can be formed by this 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, i! Electromagnetic waves include gamma rays, X-rays, ultraviolet rays,
Includes a broad definition of light that includes visible light, near-infrared light, infrared light, far-infrared light, etc.

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

Charge transporting substances include 'ltE electron transporting substances and regular transporting substances, and electron transporting substances include chloranyl,
Bromoanil, tetracyanoethylene, tetracyanoquinodimethane, 2,4,7-dolinitro-9-fluorenone, 2,4,5,7-titranitroxanthone, 2,4
．． Examples include electron-withdrawing substances such as 8-trinidrothioxanthone, and polymerization of these electron-withdrawing substances.

Examples of hole-transporting substances include pyrene, N-ethylcarbazole, N-isopropylcarbazole, N-methyl-N-
Phenylhydrazino-3-methylidene-9-ethylcarbazole, N1. , N-diphenylhydrazino-3-methylidene-9-ethylcarbasol, N,N-diphenylhydrazino-3-methylidene-10-ditylphenothiazine.

N,N-diphenylhydrazino-3-methylidene-10
-enalphenoxazine, p-diethylamide/benzaldehyde-N, N-diphenylhydrazino, p-virolidinopenzaldehyde-N.

Hydrazones such as N-diphenylhydrazone, P-diethylbenzaldehyde-3-methylbenzthianolinone-2-hydran, 2,5-his(P-diethylaminophenyl)-1,3,4-oxadiazole, l-phenyl -3-(p-diethylaminostyryl)-5-(
p-diethylaminophenyl)pyrazoline, 1-[quinolyl(2))-3-(p-diethylaminostyryl)-
5-(p-diethylaminophenyl)pyrazoline, 1-
[pyridyl (2)]-3-(p-diethylaminostyryl)-5-(p-diethylaminophenyl)pyrazoline, 1-[lepidyl (2)]-3-(p-diethylaminostyryl)-5-(p-diethylaminostyryl)-5-(p-diethylaminophenyl)pyrazoline, phenyl)
Pyrazolines such as pyrazoline, 1-[pyridyl(2)]-3-(α-methyl-p-diethylaminostyryl)-5-(p-diethylaminophenyl)pyrazoline, subirovirazoline, α-phenyl-4-N, N- styryl compounds such as diphenylaminostilbene, N-ethyl-3-(α-phenylstyryl)carbazole, 4-N,N-dibenzylamino-9-fluorenondene,
2-(p-diethyl7minostyryl)-6-dinithylaminobenzoxazole, 2-(p-diethylaminophenyl)-4-(p-dimethylaminophenyl)-5-
Oxazole compounds such as (2-chlorophenyl)oxazole, 2-(p-diethylaminostyryl)-6
-thiazole compounds such as dinithylaminobenzothiazole, triarylmethane compounds such as bis(4-diethylamino-2-methylphenyl)-phenylmethane, 1.1bis(4-N,N-diethylamino-2-methyl phenyl)hebutane, 1,1,2,2-tetrakis(4-N,N-dimethylamino-2-methylphenyl)
Polyarylalkane such as ethane, triphenylamine, poly-N-vinylcarbazole, polyvinylpyrene, polyvinylanthracene, polyvinylacridine,
Examples include poly-9-vinylphenylanthracene, pyrene-formaldehyde resin, and ethyl cartazoole-formaldehyde resin.

In addition to these 44a charge transport materials, inorganic materials such as selenium, selenium-tellurium, amorphous silicon, and cadmium sulfide can also be used.

Further, these charge transport materials 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-styrene copolymer,
Examples include insulating resins such as acrylonitrile-butadiene copolymer, polyvinyl butyral, polyvinyl formal, polysulfone, polyacrylamide, polyamide, chlorinated rubber, and organic photoconductive polymers such as poly-N-vinylcarbazole polyvinylanthracene and polyvinylpyrene. .

Since the charge transport layer has a limit in its ability to transport charge carriers, it cannot be made thicker than necessary, generally from 5 to 30. However, the preferred range is 8-20. When forming the charge transport layer using Coating I, any suitable 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. Examples of the substrate having a conductive layer include those whose substrate itself is conductive, such as aluminum, aluminum alloy, copper, zinc,
Stainless steel, vanadium, molybdenum, chromium, titanium, nickel, indium, gold, and platinum are used.

In addition, plastics (e.g., polyethylene, polypropylene, polyvinyl chloride, polyethylene terephthalate, acrylic resin, polyfluoride, (e.g., ethylene chloride), tetraelectric particles (e.g., carbon black, silver particles, etc.) are dispersed in a suitable <ingu resin>. 7. Plastics having an Ii body or a conductive polymer can be used.

A subbing layer having a barrier and adhesive function can also be provided between the conductive layer and the photosensitive layer. The subbing layer can be formed from casein, polyvinyl alcohol, nitrocellulose, ethylene-acrylic acid copolymer, polyamide (nylon 6, nylon 66, nylon 610, copolymerized nylon, alkoxymethylated nylon, etc.), polyurethane, gelatin, aluminum oxide, etc. . The appropriate thickness of the undercoat layer is 0.1 to 5 microns, preferably 0.5 to 3 microns.

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, the electrons generated in the charge generation layer are injected into the charge transport layer, and then reach the surface and neutralize the positive electrons, resulting in attenuation of the surface potential and an electrostatic charge between it and the unexposed area. Contrast occurs.

A visible image is obtained by developing the electrostatic latent image thus formed with a charged toner.

This can be directly fixed, or the toner image can be transferred to paper or plastic film and then developed and fixed.

Alternatively, a method may be used in which the static 711 latent image on the photoconductor-E is visually imaged after being transferred onto an insulating layer of a transfer paper and then 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, the surface of the charge transport layer must be negatively charged, and the charge 'i! rear,
When exposed to light, holes generated in the charge generation layer are injected into the charge transport layer in the exposed area, and then reach the surface and neutralize the negative charge, causing a decrease in surface potential and creating an electrostatic contrast between it and the unexposed area. arise. During development, it is necessary to use a positively charged toner, contrary to when an electron transporting substance is used.

Further, as another specific example of the present invention, there may be mentioned an electrophotographic photoreceptor in which Azoface 1 described above is contained in the same layer together with a charge transporting substance.

In this case, in addition to the above-mentioned charge transport materials, a charge transfer complex compound consisting of poly-N-vinylcalhesol and trinitrofluorenone can be used.

The electrophotographic photoreceptor of this example can be prepared by dispersing the azo pigment and the 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 specific azo pigments 4 having an organic residue represented by the general formula (1), and if necessary, has a light absorption property. For the purpose of increasing the sensitivity of a photoreceptor by using a combination of different pigments or obtaining a panchromatic photoreceptor, two or more types of specific azo pigments having an organic residue represented by the general formula (1) are combined, Alternatively, it can also be used 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 in electrophotographic copying machines, but also in a wide range of electrophotographic applications such as laser printers and CRT printers.

[Example] Example 1 Ammonia aqueous solution of casein (casein 1
1.2g, 28% ammonia water 1g, water 222m5L
) was applied using Mayer Parr so that the film thickness after drying was 1.0 JL and dried.

Next, 5 g of the exemplary pigment (2) was added to a solution in which 2 g of butyral resin (butyralization degree: 63 mol %) was dissolved in 95% of titrahydrofuran, and dispersed in a sand mill for 2 hours. This dispersion was applied onto the previously formed casein layer using a Mayer Par so that the film thickness after drying was 0.4%, and dried to form a charge generation layer.

5g of hydrazone compound and polymethyl methacrylate (
Dissolve 5 g of number average molecular weight (1.1 million) in 70 rsl of benzene, apply this onto the charge generation layer using a Mayer par so that the film thickness after drying is 19 ml, and dry to form a charge transport layer. An electrophotographic photoreceptor of Example 1 was prepared.

Further, electrophotographic photoreceptors corresponding to Examples 2 to 12 were prepared using other exemplary pigments in place of the exemplary face N (2).

The electrophotographic photoreceptor thus prepared was tested using an electrostatic copying paper tester (Model 5P-428, manufactured by Kawaguchi Denki ■).
Using static method, corona charge to -5.5KV, hold for 1 second in a dark place, and then expose to light at an illuminance of 5 lux.
The charging characteristics were investigated.

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

Show the results.

1 (2) 710 4.12 (
26) 730 2.33
(6) 710 2.04
(10) 700 2.95
(13) 730 3.86
(14) 700 2.67
(18) 690 2.08
(20) 670 2.9
9 (27) 710 3.
511 (32) 690 2
．． 812 (33) 700
3.5 Comparative Examples 1 to 3 Electrophotographic photoreceptors were prepared in the same manner as in Example 1, except that a 7zo pigment having the following structural formula was used in place of the 7zo pigment used in Example 1. They were evaluated in the same way. Show the results.

Azo pigment of Comparative Example 1 Azo pigment of Comparative Example 2 Azo pigment of Comparative Example 3 1 600 8.2 2 550 10.8 3 610 7.5 In view of the above results, the electrophotographic photoreceptor of the present invention has the following characteristics: It is recognized that all of them have sufficient chargeability and sensitivity compared to electrophotographic photoreceptors.

Example 13-18 The electrophotographic photoreceptor prepared in Example 2 was used in an electrostatic copying paper tester (Mod) by replacing the 780 nm semiconductor laser and its scanning unit with a tungsten light source.
el 5F-428 (7) modified machine, manufactured by Kawaguchi Denki ■), statically charged with corona at -5.5 KV,
After being held in a dark place for 1 second, it was exposed to laser light and the charging characteristics were examined.

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

Further, electrophotographic photoreceptors corresponding to Examples 14 to 18 were prepared by changing the exemplified pigments, and the charging characteristics were similarly measured. Show the results.

13 (26) 680 5.514 (
11,) 700 4.815 (15)
710 5.816 (16) 710
4.517 (34) 680 5.
918 (37) 690 4.9 From the above results, it is recognized that all the electrophotographic photoreceptors of the present invention have excellent sensitivity to laser light.

Examples 19 to 21 Using the electrophotographic photoreceptors prepared in Examples 2 and 4.5, fluctuations in bright area potential and dark area potential during repeated use were measured.

The method includes a -5.6KV corona charger, an exposure optical system, a developer, and a transfer device. The photoreceptor was attached to the cylinder of an electrophotographic copying machine equipped with F', an electric device, a static elimination exposure optical system, and a cleaner.

Using this copying machine, the initial bright area potential (VL) and dark area potential (VD) were set to -200V and -700V, respectively, and VL and vD were measured after repeated use 5,000 times. Show the results.

Comparative Examples 4 to 6 The electrophotographic photoreceptors prepared in Comparative Examples 1 to 3 were
Potential fluctuations during use of edge-reversing were measured in the same manner as above.

Show the results.

From the above results, it is recognized that the electrophotographic photoreceptor of the present invention has excellent characteristics with little potential fluctuation during repeated use.

Example 22 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 2. The coating amount after drying the coating solution prepared by dissolving 5g in 70mJL of tetrahydrofuran is 10g/m2
I applied it and let it dry.

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

vo:+700V E1/2:3,941uX,3
eC Example 23 A polyvinyl alcohol film having a film thickness of 0.5% was formed on the aluminum surface of an aluminum vapor-deposited polyethylene terephthalate film.

Next, the dispersion of the disazo pigment used in Example 2 was applied onto the polyvinyl alcohol layer formed above so that the film thickness after drying was 0.
．． It was coated with a Mayer bar so as to form five tiles, and dried to form a charge generation layer.

5 g of pyrazoline compound and 5 g of polyarylate (condensation polymer of bisphenol A and terephthalic acid-inphthalic acid)
Dissolved in 70rnl of tetrahydrofuran, !
Example 1 and Example 18 The charging characteristics and durability characteristics of the electrophotographic photoreceptor prepared by coating the charge generation layer to a film thickness of 18 μm after drying and drying to form a charge transport layer were as follows. Measured using the same method. Show the results.

Charging characteristics Vo knee 675 El/2: 3.91ux, see Durability characteristics example 24 An ammonia aqueous solution of casein was applied onto a 100JL thick aluminum plate and dried to a film thickness of 0. A subbing layer of s#L was formed.

Next, 5 g of 2,4.7-)dinitro-9-fluorenone
and 5 g of poly-N-vinylcarbazole (number average molecular weight: 9.3 million) were dissolved in 70 ml of tetrahydrofuran to form a charge transfer rust compound.

This charge transfer complex compound and exemplified pigment (33) Ig were added to a solution in which 5 g of polyester (trade name: Vylon, manufactured by Toyobo@) was dissolved in 70 mJL of tetrahydrofuran, and dispersed.

This dispersion liquid was applied onto the undercoat layer so that the film thickness after drying was 16 μm, and dried.

Example 1 Charging characteristics of the electrophotographic photoreceptor thus prepared
Measured using the same method. However, the charging polarity was set to 10. Show the results.

V6: +710 El/2: 5.0 sentences ux, sec Example 25 A casein subbing layer was provided on an aluminum plate, and the charge transport layer and charge generation layer used in Example 2 were laminated in this order on top of this. An electrophotographic photoreceptor was prepared in the same manner as in Example 2 except that the layer structure was different, and the charging characteristics were measured. However, the charging polarity was set to 10.

Vo: +685 El/2: 4.0Rux, sec [Effects of the Invention] The electrophotographic photoreceptor of the present invention contains a specific azo pigment in the photosensitive layer, thereby reducing carrier generation inside the photosensitive layer containing the azo pigment. Either or both of the efficiency and carrier transport efficiency are improved, the sensitivity and potential stability during long-term use are excellent, and the remarkable effect is that the sensitivity extends to long wavelengths.

Claims (5)

[Claims] (1) General formula ▲ Numerical formula, chemical formula, table, etc. on the conductive support ▼ (I) (In the formula, R_1 and R_2 are hydrogen atoms, alkyl groups that may have substituents, aralkyl groups, aryl group, heterocyclic group, nitro group, cyano group, halogen atom, halomethyl group, or substituted amino group, which may be the same or different, and R_1 and R_2 may jointly have a substituent. The organic residues indicated by ), which may form a good ring, are
1. An electrophotographic photoreceptor comprising a photosensitive layer containing an azo pigment having a structure bonded to a substituted or unsubstituted aromatic hydrocarbon ring or aromatic heterocycle which may be bonded via a bonding group. (2) The azo pigment has the general formula ▲ Numerical formula, chemical formula, table, etc. ▼ (II) (In the formula, Ar is a substituted or unsubstituted aromatic hydrocarbon ring that may be bonded via a bonding group or represents an aromatic heterocycle, R_1 and R_2 have the same meanings as in general formula (I), and n is an integer of 1, 2, 3 or 4;
) The electrophotographic photoreceptor according to claim 1, which is an azo pigment represented by: (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 -N=N-Cp (III) different from the selected organic residues. (In the formula, Cp represents a coupler residue having a phenolic hydroxyl group.) A substituted or unsubstituted aromatic compound which may be bonded to at least one organic residue in the same molecule via a bonding group. The electrophotographic photoreceptor according to claim 1, which is an azo pigment having a structure bonded to a hydrocarbon ring or an aromatic heterocycle. (4) The photosensitive layer contains at least one azo pigment represented by the general formula (II) and at least one organic residue selected from the organic residues represented by the general formula (I). General formula -N=H-Cp(III) different from organic residue (
In the formula, Cp represents a coupler residue having a phenolic OH group.) A substituted or unsubstituted aromatic compound which may be bonded to at least one of the organic residues represented by ) through a bonding group within the same molecule. 3. The electrophotographic photoreceptor according to claim 1, which contains at least one azo pigment having a structure bonded to a group hydrocarbon ring or an aromatic heterocycle. (5) It has a structure in which the conductive layer and the organic residue represented by general formula (I) are bonded to a substituted or unsubstituted aromatic hydrocarbon ring or aromatic heterocycle which may be bonded via a bonding group. The electrophotographic photoreceptor according to claim 1, comprising at least three layers: a charge generation layer containing an azo pigment and a charge transport layer.