JPS6329761A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To enhance sensitivity, durability, potential stability, and the like by incorporating a specified diazo pigment in a photoconductive layer. CONSTITUTION:The disazo pigment having a structure of a general formula I (each of R1 and R2 is H, alkyl, alkoxy, halogen, nitro, or cyano, and each of A1 and A2 is a coupler residue having a phenolic OH group) is incorporated in the photoconductive layer, thus permitting efficiencies of carrier generation and carrier transfer to be enhanced, and sensitivity, durability, and potential stability to be also enhanced by forming an organic semiconductor good in color sensitivity on the substrate of an electrophotographic sensitive body.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a novel electrophotographic photoreceptor, and more particularly to an electrophotographic photoreceptor containing a disazo pigment having a specific molecular structure in a photoconductive layer. It is something.

Support 1 Distortion Dan 11 Conventionally, pigments and dyes exhibiting photoconductivity have been published in numerous publications.

For example, "RCA Review" Vol. 1.23.
P, 413 to P, 419 (1962, 9) have published on the photoconductivity of phthalocyanine pigments, and electrophotographic photoreceptors using these phthalocyanine pigments have been published in U.S. Patent No. 3,397,086 and US Patent No. 3
It is shown in the publication No. 816.118 and the like. Other,
Examples of organic semiconductors used in electrophotographic photoreceptors include U.S. Pat. No. 4,315,983 and U.S. Pat. No. 4,32.
Publication No. 7゜169 and Re5each Disclos
ure” 20517 (1981, 5), methine squaric acid dyes shown in U.S. Pat. No. 3,824,099, U.S. Pat. Patent No. 4,251,
Examples include disazo pigments shown in Publication No. 613 and the like.

Such organic semiconductors are easier to synthesize than inorganic semiconductors, and can be synthesized as compounds that have photoconductivity for light in the required wavelength range. An electrophotographic photoreceptor formed on a conductive support has the advantage of good color sensitivity, but very few of them are practical in terms of sensitivity and durability.

SUMMARY OF THE INVENTION An object of the present invention is to provide a novel photoconductive material.

Another object of the present invention is to provide an electrophotographic photoreceptor that can be used in all current electrophotographic processes and has practical high sensitivity characteristics and stable potential characteristics during repeated use.

A second object is to provide an electrophotographic photoreceptor having a wide spectral sensitivity spanning from the visible region to the near-infrared and infrared regions.

The present invention comprises a photoconductive film containing a disazo pigment represented by the following general formula (1).

General Formula In the general formula (,1), R and R2 represent hydrogen, an alkyl group that may have a substituent, an alkoxy group, a halogen group, a nitro group, and a cyano group, and specifically, methyl, ethyl, Propyl, isopropyl, butyl, 5eC-butyl, t-
Indicates butyl, methoxy, ethoxy, propoxy, fluorine, chlorine, iodine, bromine, nitro, furyl, thionyl, pyroyl, etc.

Substituents for the alkyl group and alkoxy group represented by R, R2 include halogen groups such as fluorine, chlorine, iodine, and bromine;
Substitution of alkyl groups such as methyl, ethyl, propyl, isopropyl, butyl, alkoxy groups such as methoxy, ethoxy, propokine, phenoxy, nitro group, cyano group, dimethylamino, dibenzylamino, diphenylamino, morpholino, piperidino, pyrrolidino, etc. Examples include amine groups.

In the general formula (1), (7) A, , A2 represent a coupler residue having a phenolic OH group, and more preferable examples of the coupler residue represented by A, , A2 include the general formula (2) % formula % In formula (2), X is condensed with a benzene ring to form a polycyclic aromatic ring such as a naphthalene ring, anthracene ring, carbazole ring, benzcarbazole ring, dibenzofuran ring, nobenzonaphthofuran ring, or diphenylene sulfide ring. Indicates residues necessary to form a ring or a heterocycle.

The ring to which X is bonded is more preferably a naphthalene ring, an anthracene ring, a carbazole ring, or a benzcarbazole ring.

In formula (2), R3 and R4 represent hydrogen, an alkyl group which may have a substituent, an aryl group, an aralkyl group, a heterocyclic group, or a cyclic amino group together with the nitrogen atom to which R3 and R4 are bonded.

Specific examples of alkyl groups include methyl, ethyl, propyl, butyl, etc. Specific examples of aralkyl groups include benzyl, phenethyl, naphthylmethyl, etc. Specific examples of aryl groups include phenyl, diphenyl, naphthyl, anthryl, etc. Specific examples of the heterocyclic group include carbazole, dibenzofuran, benzimidacylone, benzthiazole, thiazole, pyridine, and the like.

R5 and R6 in the general formulas (3) and (4) represent hydrogen, an alkyl group that may have a substituent, an aryl group, or an aralkyl group. Specific examples of R5 and R6 are shown by the same example as R3°R4.

The alkyl group, aryl group, aralkyl group, alkoxy group, and heterocyclic group represented by the substituents R3 to R6 in formulas (2) to (4) may further include other substituents such as fluorine, chlorine, iodine,
Halogen groups such as bromine, alkyl groups such as methyl, ethyl, propyl, isopropyl, butyl, alkoxy groups such as methoxy, ethoxy, propoxy, phenoxy, nitro groups, cyan groups, dimethylamino, dibenzylamino, diphenylamino, It may be substituted with a substituted amino group such as morpholino, piperidino, or pyrrolidino.

General formula % Formula % Y in formulas (5) and (6) represents a divalent group of aromatic hydrocarbon or a divalent group of heterocycle containing a nitrogen atom in the ring.

Examples of divalent groups of aromatic hydrocarbons include divalent groups of monocyclic aromatic hydrocarbons such as 0-phinidine, 0-naphthylene, perinaphthylene, 1,2-antrylene, and 9.10-phenanthrylene. Examples include divalent groups of condensed polycyclic aromatic hydrocarbons such as. Also, 2 of a heterocycle containing a nitrogen atom in the ring
As the valent group, 3,4-pyrazolediyl group, 2,3
-pyridinediyl group, 4,5-pyrimidinediyl group, 6
．． Divalent groups such as 7-indazolediyl group and 6,7-chiralindiyl group can be mentioned.

R7 in the general formula (7) represents an aryl group or a heterocyclic group which may have a substituent, and specifically represents a phenyl, naphthyl, anthryl, pyrenyl, pyridyl, chenyl, furyl, or carbazolyl group. .

Substituents for the aryl group and heterocyclic group represented by R7 include halogen groups such as fluorine, chlorine, iodine, and bromine, alkyl groups such as methyl, ethyl, propyl, isopropyl, and butyl, and alkoxy groups such as methoxy, ethoxy, propoxy, and phenoxy. Examples include substituted amine groups such as nitro group, cyano group, dimethylamino, diphenylamino, diphenylamino, morpholino, piperidino, and pyrrolidino.

R8 and R8 in the general formula (8) represent an alkyl group, an aryl group, an aralkyl group, or a heterocyclic group which may have a substituent, specifically methyl, ethyl, propyl, butyl, benzyl , phenethyl, naphthylmethyl, phenyl, naphthyl, anthryl, diphenyl, carbazole,
Indicates dibenzofuran, benzimidasilone, benzthiazole, thiazole, and pyridine.

Substituents for the alkyl group, aryl group, aralkyl group, and heterocyclic group represented by R8 and R8 in formula (8) include fluorine,
Halogen groups such as chlorine, iodine, bromine, methyl, ethyl,
Examples include alkyl groups such as propyl, isopropyl, butyl, alkoxy groups such as methoxy, ethoxy, propoxy, and phenoxy, and substituted amino groups such as nitro group, cyano group, dimethylamino, dibenzylamino, diphenylamino, morpholino, piperidino, and pyrrolidino. It will be done.

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

Table 1 The disazo pigments shown in the above specific examples are not intended to limit the scope of the claims of the present invention.

These diazo pigments can be used alone or in combination of two or more. Further, these pigments used in the present invention can be prepared by, for example, treating the extracted diamine of the general formula (9) with a nitrite in a conventional manner to form a tetrazonium.
Next, phenolic O represented by general formulas (2) to (8)
After aqueous coupling of the H-containing coupler in the presence of an alkali or isolation of the tetrazinium salt of the diamine in the form of BF4 salt, PF6 salt or zinc chloride double salt, etc., a suitable solvent such as N 2 , N - It can be easily produced by coupling with a coupler in a solvent such as dimethylformamide or dimethyl sulfoxide in the presence of an alkali. Next, a typical synthesis example of the disazo pigment used in the present invention is shown below.

Synthesis example (synthesis of the above-exemplified disazo pigment No. 1) 50
0ml beaker with 180rrl of water and 37.4ml of concentrated hydrochloric acid
mj7 (0.44 mol) was added, and the mixture was stirred while cooling in an ice-water bath to bring the liquid temperature to 3°C. Next, sodium nitrite 9.5
g (0.14 mol) in 15 tnI of water! was added dropwise over 25 minutes while controlling the liquid temperature within the range of 0 to 5°C, and after the addition was completed, the mixture was further stirred at the same temperature for 30 minutes.

Carbon was added to the reaction solution and filtered to obtain a tetrazo solution.

Next, put 1.5 + 4' of water in a beaker 31, dissolve 47.3 g (1,18 mol) of sodium hydroxide, and then dissolve 36.3 g (0,138 mol) of naphthol AS (3-hydroxy-2-naphthoic acid anilide). ) was added and dissolved. This coupler solution was cooled to 6°C, and the liquid temperature was adjusted to 6-10°C.
The above-mentioned tetrazotization solution was heated at 30°C while controlling the temperature.
The mixture was added dropwise over a period of minutes with stirring, then stirred for 2 hours, and further left overnight. The reaction solution was filtered and washed with water to obtain 51.5 g of water paste in terms of solid content. Next is 900mj! The stirring filtration was repeated four times at room temperature using N,N-dimethylformamide. Then 2 with 900mf M E K
After repeated stirring and filtration, the purified pigment was dried under reduced pressure.
6 g (yield: 85.3%) was obtained.

Melting point>300°C Elemental analysis calculated value (%) Experimental value C70,6770,62 H3,693,65 N 10.99 10.97 The synthesis method of typical pigments has been described above, but - general formula (1) Other disazo pigments represented by are also synthesized in the same manner.

The coating containing the above-mentioned disazo pigment exhibits photoconductivity and can therefore be used in the photosensitive layer of the above-mentioned electrophotographic photoreceptor.

That is, in a specific example of the present invention, an electrophotographic photoreceptor is prepared by forming a film of the above-mentioned disazo pigment on a conductive support by vacuum evaporation, or by dispersing it in a suitable binder and forming a film. can do.

In a preferred embodiment of the present invention, the photoconductive coating described above can be applied as a charge generation layer in an electrophotographic photoreceptor in which the photosensitive layer is functionally separated into a charge generation layer and a charge transport layer.

The charge generation layer contains as much of the above-mentioned photoconductive diazo pigment as possible in order to obtain sufficient absorbance, and the generated charge carriers efficiently reach the interface between the charge transport layer and the conductive substrate. coating layer, to be transported
For example, it is preferable to use a thin film layer having a thickness of 5 μm or less, preferably 0.01 to 1 μm. 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 diazo pigment in a suitable binder and coating it on a substrate, or can be obtained by forming a deposited film using a vacuum deposition apparatus. The binder that can be used when forming the charge generation layer by coating can be selected from a wide range of insulating resins, including poly-N-vinylcarbazole,
It can be selected from organic photoconductive polymers such as polyvinylanthracene and polyvinylpyrene. Preferably, polyvinyl butyral, polyvinylpenzole polyarylate (condensation polymer of bisphenol A and phthalic acid, etc.), polycarbonate, polyester, phenoxy resin, polyvinyl acetate, acrylic resin, polyacrylamide resin, polyamide, polyvinylpyridine, cellulose resin. , urethane resin, epoxy resin, casein, polyvinyl alcohol, polyvinylpyrrolidone, and other insulating resins. The resin contained in the charge generation layer is 80
Weight % or less, preferably 40 weight % or less is suitable.

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. At this time, this charge transport layer may be laminated on or under the charge generation layer.

When the charge transport layer is formed on the charge generation layer, the material that transports charge carriers in the charge transport layer (hereinafter simply referred to as charge transport material) is substantially in the wavelength range of electromagnetic waves to which the charge generation layer is sensitive. Preferably, it is insensitive to. The term "electromagnetic waves" used herein includes a broad definition of "light rays" that includes 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 examples of electron-transporting substances include chloranil, tetracyanoethylene, tetracyanoquinodimethane, and 2.
4. 5. 7-tetranitro-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-methyl-N-phenylhydrazino-3-methylidene-9-ethylcarbazole, and N,N-diphenylhydrazino-3-methylidene-10-ethyl. Phenothiazine, P-diethylaminobenzaldehyde-N,N
-Diphenylhydrazone, P-pyrrolidinobenzaldehyde-N,N-diphenylhydrazone, P-diethylbenzaldehyde-3-methylbenzthiazolinone-2-
Hydrazones such as hydrazone, 2,5-bis(P-diethylaminophenyl)-1,3,4-oxadiazole, ■-phenyl-3-(P-diethylaminostyryl)-5-(P-diethylaminophenyl)pyrazoline,
1-[pyridyl(2)3-3-(P-diethylaminostyryl)-5-(P-diethylaminophenyl)pyrazoline, 1-[pyridyl(3))-3-(P-diethylaminostyryl)-5-(P -diethylaminophenyl)
Pyrazoline, ■-[pyridyl (2)) -3-(P-diethylaminostyryl, 4-methyl-5-(p-diethylaminophenyl)pyrazoline, 1-phenyl-3-(
P-diethylaminostyryl)-4-methyl-5-(P
Pyrazolines such as -diethylaminophenyl)pyrazoline and spiropyrazoline, 2-(P-diethylaminostyryl)-6-dinithylaminobenzoxazole, 2
- Oxazole compounds such as (P-diethylaminophenyl)-4-(P-dimethylaminophenyl)-5-(2-chlorophenyl)oxazole, 2-(P-diethylaminostyryl)-6-dinithylaminobenzothiazole, etc. Thiazole compounds, triarylmethane compounds such as bis(4-diethylamine-2-methylphenyl)-phenylmethane, l, 1-bis(4-N,
N-diethylamino-2-methylphenyl)hebutane,
1. l, 2. 2-tetrakis (4-N, N-
Polyarylalkanes such as dimethylamino-2-methylphenyl)ethane, triphenylamine, poly-N-
Examples include vinylcarbazole, polyvinylpyrene, polyvinylanthracene, polyvinylacridine, poly-9-vinylphenylanthracene, pyrene-formaldehyde resin, and ethylcarbazole 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,
polyacrylate, polyester, polycarbonate,
Polystyrene, acrylonitrile-styrene copolymer, acrylonitrile-butadiene copolymer, polyvinyl butyral, polyvinyl formal, polysulfone,
Examples include insulating resins such as polyacrylamide, polyamide, and 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, it is 5 to 30μ, but the preferred range is 8 to 20μ.
It is. When forming the charge transport layer by coating, an appropriate coating method as described above can be used.

A photosensitive layer having such a laminated structure of a charge generation layer and a charge transport layer is provided on a substrate having a conductive layer. Examples of substrates having a conductive layer include those in which the substrate itself is conductive;
For example, aluminum, aluminum alloy, copper, zinc, stainless steel, vanadium, molybdenum, chromium, titanium,
Nickel, indium, gold, platinum, etc. can be used, and plastics (for example, polyethylene , polypropylene, polyvinyl chloride, polyethylene terephthalate, acrylic resin,
(polyfluorinated ethylene, etc.), substrates made of plastic coated with conductive particles (e.g. carbon black, silver particles, etc.) together with a suitable binder, substrates made of plastic or paper impregnated with conductive particles, and plastics with conductive polymers. etc. can be used.

A subbing layer having barrier and adhesive functions can also be provided between the conductive layer 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, gelatin,
It can be formed from aluminum oxide, etc.

The thickness of the subbing layer is 0.1 to 5μ, preferably 0.5 to 3μ.
μ is appropriate.

When using a photoreceptor in which a conductive layer, a charge transport layer, and a charge generation layer are laminated in this order, if the charge transport substance is an electron transport substance, the surface of the charge generation layer must be negatively charged, and exposure after charging is required. Then, in the exposed portion, electrons generated in the charge generation layer are injected into the charge transport layer, and then reach the substrate. On the other hand, holes generated in the charge generation layer reach the surface and the surface potential is attenuated, creating an electrostatic contrast with the unexposed area. A visible image can be obtained by developing the electrostatic latent image thus formed with a positively charged toner.

This can be directly fixed, or the toner image can be visually imaged and fixed after being transferred to paper, plastic film, or the like. Alternatively, a method may be used in which the electrostatic latent image on the photoreceptor is transferred onto an insulating layer of transfer paper, and then visually imaged and fixed. The type of developer, the developing method, and the fixing method may be any conventional or known method, and are not limited to specific ones.

On the other hand, when the charge generation layer is made of a hole transporting substance, the surface of the charge generation layer must be positively charged, and when exposed to light after charging, the holes generated in the charge generation layer are injected into the charge transport layer in the exposed area. and then reaches the base. On the other hand, electrons generated in the charge generation layer reach the surface and the surface potential is attenuated, creating an electrostatic contrast with the unexposed area. During development, it is necessary to use a negatively charged toner, contrary to the case where an electron transporting substance is used.

Another specific example of the present invention is an electrophotographic photoreceptor containing a disazo pigment represented by the above-mentioned general formula (1) together with a charge transport material in the same layer. In this case, in addition to the above-mentioned charge transport materials, a charge transfer complex compound consisting of poly-N-vinylcarbazole and trinitrofluorenone can be used. The electrophotographic photoreceptor of this example can be prepared by dispersing the aforementioned disazo 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 photoreceptors contains at least one type of pigment selected from disazo pigments represented by the general formula (1), and its crystal form may be amorphous or crystalline. Furthermore, if necessary, two or more types of disazo pigments represented by the general formula (1) may be used in combination for the purpose of increasing the sensitivity of the photoreceptor or obtaining a panchromatic photoreceptor by using a combination of pigments with different light absorptions. Alternatively, it can 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 for electrophotographic copying machines, but also for laser printers, CRf printers, L
It can also be widely used in electrophotographic applications such as ED printers, liquid crystal printers, and laser engraving.

Hereinafter, the present invention will be explained by examples.

Examples 1 to 15 Ammonia aqueous solution of casein (casein 1
d.2 It was coated and dried using a Mayer bar so that the film thickness after drying was 1.0 μm.

Next, 1.5 g of the above-exemplified disazo pigment No. 1 was added to a solution prepared by dissolving 2 g of butyral resin (degree of butyralization: 63 mol %) in 95 mj2 of ethanol, 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 0.5 μm, and dried to form a charge generation layer. Next, 5 g of the hydrazone compound with the structural formula and 5 g of polymethyl methacrylate resin (number average molecular weight 100,000) were mixed with 70 g of benzene.
The photoreceptor of Example 1 was prepared by dissolving this in ml and applying it onto the charge generation layer using a Mayer bar so that the dry film thickness was 12μ, and drying to form a charge transport layer.

Photoreceptors corresponding to Examples 2 to 15 were prepared in exactly the same manner using other exemplary pigments shown in Tables 1 to 5 in place of disazo pigment No. 1.

The electrophotographic photoreceptor produced in this way was manufactured by Kawaguchi Electric Co., Ltd.
Manufactured electrostatic copying paper testing device MODE ISP
- 428 was used to perform static corona charging at 15 KV, held in a dark place for 1 second, and then exposed to light at an illuminance of 2 lux to examine charging characteristics.

As for the charging characteristics, the surface potential (■0) and the exposure amount (E!4) required to attenuate the potential to A after dark decaying for 1 second were measured. The results are shown in Table 2.

From the results shown in Table 2 and Table 1, it can be seen that all the photoreceptors of the present invention have sufficient charging ability and sufficient sensitivity.

Examples 16 to 20 Using the photoreceptors used in Examples 1, 2, 4, 6, and 10, fluctuations in bright area potential and dark area potential during repeated use were measured. This copying machine is equipped with a -5.6KV corona charger, an exposure optical system, a developer, a transfer charger, a static elimination exposure optical system, and a cleaner, and the photoreceptor is attached to the cylinder of an electrophotographic copying machine. The structure is such that an image is obtained on the transfer paper as the transfer unit is driven.

Using this copying machine, the initial bright area potential (VL) and dark area potential (VD) were each -100V.

The results of measuring the bright area potential (VL) and dark area potential (VD) after 5,000 uses at around -600V are shown in the third table.
Shown in the table.

Table 3 Example 21 On the charge generation layer prepared in Example 1, 5 g of 2,4,7-dolinitro-9-fluorenone and poly-4゜4'-dioxydiphethi-2,2'-propane carbonate (
5g (molecular weight: 300,000) in tetrahydrofuran (70%)
m1! The coating amount after drying is 1.
It was coated at a concentration of 0 g/m2 and dried.

The electrostatic charge of the electrophotographic photoreceptor thus prepared was measured in the same manner as in Example 1. At this time, the charging polarity was set to ten. The results are shown in Table 4.

Table 4 VO: 0580 volts Ey2: 3.4I! uX+SeC Example 22 A polyvinyl alcohol film having a thickness of 0.5 μm was formed on the aluminum surface of an aluminum vapor-deposited polyethylene terephthalate film. Next, the disazo pigment dispersion used in Example 1 was applied onto the previously formed polyvinyl alcohol layer using a Mayer bar so that the film thickness after drying was 0.5μ, and dried to form a charge generation layer. did.

5 g of pyrazoline compound and polyarylate resin (condensation polymer of bisphenol A and terephthalic acid-isophthalic acid)
5g to 70mj of tetrahydrofuran! A solution dissolved in the above was applied onto the charge generation layer so that the film thickness after drying was 10 μm, and dried to form a charge transport layer. The charging characteristics and durability characteristics of the photoreceptor thus prepared were shown in Examples 1 and 16.
It was measured by the same method as in ~20. This result is the fifth
Shown in the table.

Table 5 Vo: () 590 volts E V2: 3.8 i! As shown in Table 5 of ux/sec durability characteristics, the sensitivity is good and the potential stability during long-term use is also good.

Example 23 An ammonia aqueous solution of casein was coated on an aluminum plate with a thickness of 100 μm and dried to form a subbing layer with a thickness of 0.5 μm.

Next, 5 g of 2,4.7-dolinitro-9-fluorenone
and poly-N-vinylcarbazole (number average molecular weight 300
000) was dissolved in 70 mj7 of tetrahydrofuran to form a charge transfer complex compound. This charge transfer complex compound and 1 g of the above-exemplified disazo pigment No. 3 were added to and dispersed in a solution in which 5 g of polyester resin (manufactured by Byron Nito Ibo) was dissolved in 70 ml of tetrahydrofuran. This dispersion was applied onto the undercoat layer and dried to prepare a 12μ photoreceptor.

The charging characteristics of the photoreceptor thus prepared were measured in the same manner as in Example 1. The results are shown in Table 6. However, the charging polarity was O.

Table 6 VO: (E) 600V E V2: 2.5, &uxIsec Example 24 The charge transport layer and charge generation layer of Example 1 were placed on the casein layer of the aluminum base coated with the casein layer used in Example 23. A photoreceptor was formed in the same manner as in Example 1 except that the layers were sequentially laminated and the layer structure was different, and the charging characteristics were measured in the same manner as in Example 1. However, the charging polarity was set to ■.

The results are shown in Table 7.

Table 7 ■ o: ■ 600v Ey2: 3.8 Aux-sec Example 25 When the photoreceptor used in Example 11 was exposed to a semiconductor laser having an oscillation wavelength of 780 nm, the spectral sensitivity at 780 nm was 1.4 μJ/Cm2 (Half exposure amount).

Next, this photoreceptor was applied to the drum of Canon LEP-CX and a photographic test was conducted, and a good image without fogging was obtained. Moreover, this did not change even after repeating this 10,000 times.

Example 25 In Example 25, instead of Exemplified Compound 25, 18°19
, 24. 26 was used, but a drum-shaped
A photoreceptor was created. The spectral sensitivity of each photoreceptor at 780 nm was as shown in Table 8.

Table 8 Exemplary Compounds 18. 19. 24.
26 Half-decreased exposure amount (u J/cm2) 1.6 2.
3 2.1 2.0 Next, a live photo test was conducted in the same manner as in Example 25, and a fog-free image was obtained.
There was no change even if this was repeated 10,000 times.

<Effects of the Invention> According to the present invention, it is estimated that by using a specific azo pigment in a photosensitive layer, either or both of carrier generation efficiency and carrier transport efficiency within the photosensitive layer containing the azo pigment will be improved. As a result, a photoreceptor with high sensitivity and excellent potential stability during long-term use can be obtained. Further, even in the oscillation wavelength range of a semiconductor laser, it is possible to obtain a good image with high sensitivity and no fog.

Claims (8)

[Claims] (1) An electrophotographic photoreceptor having a photoconductive layer on a conductive substrate, characterized in that the photoconductive layer contains a disazo pigment represented by the general formula (1). ▲There are mathematical formulas, chemical formulas, tables, etc.▼(1) However, in the formula, R_1 and R_2 represent hydrogen, an alkyl group, an alkoxy group, a halogen group, a nitro group, or a cyano group,
R_1 and R_2 may be the same or different. In the formula, A_1 and A_2 represent coupler residues having a phenolic OH group, and A_1 and A_2 may be the same or different. (2) The electrophotographic photoreceptor according to claim (1), wherein A_2 of A_1 and A_2 in general formula (1) are represented by the following general formula (2). General formula ▲ Numerical formula, chemical formula, table, etc. ▼ (2) In formula (2), X represents a residue necessary to form a polycyclic aromatic ring or a heterocycle by condensation with a benzene ring. In formula (2), R_3 and R_4 are hydrogen, an alkyl group that may have a substituent, an aryl group that may have a substituent, an aralkyl group that may have a substituent, and a substituent. A heterocyclic group that may have R_3, R_
It shows a cyclic amino group together with the nitrogen atom to which 4 is bonded. (3) The electrophotographic photoreceptor according to claim (1), wherein A_1 and A_2 in general formula (1) are represented by the following general formula (3). General formula ▲ Numerical formula, chemical formula, table, etc. ▼ (3) R_5 in formula (3) is an alkyl group, aryl group, or aralkyl group, and these groups may have a substituent. (4) A_1 and A_2 in general formula (1) are expressed by the following general formula (
4) The electrophotographic photoreceptor according to claim (1). General formula ▲ Numerical formula, chemical formula, table, etc. ▼ (4) R_6 in formula (4) is an alkyl group, aryl group, or aralkyl group, and these groups may have a substituent. (5) The electrophotographic photoreceptor according to claim (1), wherein A_1 and A_2 in general formula (1) are represented by the following general formula (5). General formula ▲ Numerical formula, chemical formula, table, etc. ▼ (5) Y in formula (5) represents a divalent group of an aromatic hydrocarbon or a divalent group of a heterocyclic ring containing a nitrogen atom in the ring. (6) A_1 and A_2 in general formula (1) are expressed by the following general formula (
6) The electrophotographic photoreceptor according to claim (1). General formula ▲ Numerical formula, chemical formula, table, etc. ▼ (6) Y in formula (6) represents a divalent group of an aromatic hydrocarbon or a divalent group of a heterocyclic ring containing a nitrogen atom in the ring. (7) A_1 and A_2 in general formula (1) are expressed by the following general formula (
7) The electrophotographic photoreceptor according to claim (1). General formula ▲ Numerical formula, chemical formula, table, etc. ▼ (7) In formula (7), R_7 represents an aryl group that may have a substituent or a heterocyclic group that may have a substituent, X represents the same meaning as X in general formula (2). (8) A_1 and A_2 in general formula (1) are expressed by the following general formula (
8) The electrophotographic photoreceptor according to claim (1). General formula ▲ Numerical formula, chemical formula, table, etc. ▼ (8) In formula (8), R_8 and R_9 are an alkyl group, an aryl group, an aralkyl group, or a heterocyclic group, and these groups have a substituent. It's okay. X represents the same meaning as X in general formula (2).