JP2511290B2 - Electrophotographic photoreceptor - Google Patents

Description

Description: TECHNICAL FIELD 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.

[Prior Art] Conventionally, pigments and dyes exhibiting photoconductivity have been announced in many documents.

For example, "RCA Review" Vol.23, P.413-P.419 (1962.
In 9), the photoconductivity of phthalocyanine pigment was announced, and electrophotographic photoreceptors using this phthalocyanine pigment are described in US Pat. No. 3397086 and US Pat. No. 3816118. . Other,
Examples of organic semiconductors used for electrophotographic photoreceptors include US Pat. No. 4,315,983, US Pat. No. 4,327,169 and Pyrylium dyes described in “Reseach Disclosure” 20517 (1981.5), US Pat. No. 3824099. Examples include squaric acid methine dyes described in the specification, disazo pigments described in US Pat. No. 3898084, US Pat. No. 4251613, and the like.

Such an organic semiconductor is easier to synthesize than an inorganic semiconductor and can be synthesized as a compound having photoconductivity with respect to light in a required wavelength range. The electrophotographic photosensitive member formed on the conductive substrate has an advantage that the color sensitivity is improved,
Only a few are practical in terms of sensitivity and durability.

[Problems to be Solved by the Invention] An object of the present invention is to provide a novel photoconductive material,
An object of the present invention is to provide an electrophotographic photosensitive member that can be used in all current electrophotographic processes and has practically high sensitivity characteristics and stable potential characteristics in repeated use.

[Means and Action for Solving the Problems] The present invention is an electrophotographic photoreceptor having a photoconductive layer on a conductive substrate, characterized in that the photoconductive layer contains a disazo pigment represented by the following general formula (1). It is composed of an electrophotographic photosensitive member.

General formula In the formula, R ₁ and R ₂ represent an alkyl group, an aromatic hydrocarbon group or an aromatic heterocyclic group, the above groups may have a substituent, and R ₁ and R ₂ may be the same or different. May be
A ₁ and A ₂ represent a coupler residue having a phenolic hydroxyl group, and A ₁ and A ₂ may be the same or different.

Specifically, R ₁ and R ₂ are alkyl groups such as methyl, ethyl, propyl, isopropyl and butyl, and aromatic hydrocarbon groups such as phenyl, naphthyl and benzyl. As the aromatic heterocyclic group,
Examples thereof include groups such as pyridyl and quinolyl.As the substituents of the above groups, halogen atoms such as fluorine atom, chlorine atom and bromine atom, alkyl groups such as methyl, ethyl, propyl, isopropyl and butyl, methoxy and ethoxy, Alkoxy groups such as propoxy and phenoxy, nitro groups, cyano groups, dimethylamino, dibenzylamino,
Substituted amino groups such as diphenylamino, morpholino and piperidino are mentioned.

More preferable specific examples of the coupler residue having a phenolic hydroxyl group represented by A ₁ and A ₂ include the residues represented by the following general formulas (2) to (6).

General formula In the formula, X is condensed with a benzene ring to form a naphthalene ring, an anthracene ring, a carbazole ring, a benzocarbazole ring,
The residues necessary for forming a polycyclic aromatic ring or a heterocycle such as a dibenzcarbazole ring, a dibenzofuran ring, a dibenzonaphthofuran ring, a diphenylene sulfite ring and a fluorenone ring are shown.

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

R ₃ and R ₄ represent a hydrogen atom, an alkyl group, an aryl, an aralkyl group, or a heterocyclic group, and the above groups may have a substituent, or R ₃ and R ₄ are cyclic amino groups together with a nitrogen atom to be bonded. Indicates.

Specifically, examples of the alkyl group include groups such as methyl, ethyl, propyl, and butyl, examples of the aralkyl group include groups such as benzyl, phenethyl, and naphthylmethyl, examples of aryl groups include groups such as phenyl, diphenyl, naphthyl, and anthryl. Examples of the cyclic group include groups such as carbazole, dibenzofuran, benzimidazolone, benzthiazole, thiazole and pyridine.

General formula In the formula, R ₅ represents a hydrogen atom, an alkyl group, an aryl group or an aralkyl group, and the above group may have a substituent. Specifically, it is shown by the same example as the above R ₃ and R ₄ of R ₅ .

The alkyl group, aryl group, aralkyl group, and heterocyclic group represented by the substituents R _{3 to} R _{5 in} the general formulas (2) and (3) may be further substituted with other substituents such as a fluorine atom, a chlorine atom, an iodine atom, Halogen atom such as bromine atom, alkyl group such as methyl, ethyl, propyl, isopropyl, butyl, alkoxy group such as methoxy, ethoxy, propoxy, phenoxy, nitro group, cyano group, dimethylamino, dibenzylamino, diphenylamino, morpholino , Piperidino, pyrrolidino and the like, which may be substituted with a substituted amino group.

General formula In the formula, Y represents a divalent group of an aromatic hydrocarbon or a divalent group of a hetero ring containing a nitrogen atom in the ring, and the divalent group of the aromatic hydrocarbon is a monocyclic ring such as o-phenylene. Aromatic hydrocarbon divalent groups, condensed polycyclic aromatic hydrocarbon divalent groups such as o-naphthylene, perinaphthylene, 1,2-anthrylene, and 9,10-phenanthrylene. Examples of the divalent group of the heterocycle include, 3,4-pyrazolediyl group, 2,3-pyridinediyl group, 4,5-pyrimidinediyl group, 6,7-indazolediyl group, 6,7-quinolinediyl group. And a divalent group such as

General formula In the formula, R ₆ represents an aryl group or a heterocyclic group, and the above group may have a substituent. Specifically, as the aryl group, a group such as phenyl, naphthyl, anthryl, pyrenyl, etc. Include groups such as pyridyl, thienyl, furyl and carbazolyl.

Further, as the substituent of the aryl group and the heterocyclic group, a halogen atom such as a fluorine atom, a chlorine atom, an iodine atom and a bromine atom, an alkyl group such as methyl, ethyl, propyl, isopropyl and butyl, methoxy, ethoxy, propoxy, phenoxy and the like. Alkoxy group, nitro group, cyano group, dimethylamino, dibenzylamino, diphenylamino, morpholino, piperidino, pyrrolidino and other substituted amino groups.

 X has the same meaning as X in the general formula (2).

General formula In the formula, R ₇ and R ₈ represent an alkyl group, an aralkyl group, an aryl group, or a heterocyclic group, and the above group may have a substituent, and specific examples of the alkyl group include methyl, ethyl and propyl. , Butyl and the like groups, aralkyl groups such as benzyl, phenethyl and naphthylmethyl groups, and aryl groups such as phenyl, diphenyl and naphthyl,
A group such as anthryl, carbazolyl as a heterocyclic group,
Examples thereof include groups such as thienyl, pyridyl, and furyl, and the substituents of the above groups include halogen atoms such as fluorine atom, chlorine atom, iodine atom, and bromine atom, and alkyl groups such as methyl, ethyl, propyl, isopropyl, and butyl. And 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.

 X has the same meaning as X in the general formula (2).

Typical examples of the disazo pigment represented by the general formula (1) of the present invention are listed below.

In the basic type, the exemplified pigment has a different part R ₁ ,
Only R ₂ , A ₁ , and A ₂ are described to represent a specific structure.

Basic type The disazo pigments shown in the above specific examples do not limit the claims of the present invention.

These disazo pigments can be used alone or in combination of two or more.

These disazo pigments are, for example, diamines of the following structural formula It is treated with nitrite by a conventional method to form tetrazonium, and then a coupler having a coupler residue having a phenolic hydroxyl group represented by the general formulas (2) to (6) is water-coupled in the presence of an alkali, or After the tetrazonium salt of diamine is once isolated in the form of BF ₄ salt, PF ₆ salt or zinc chloride double salt, a suitable solvent such as N, N-
It can be easily synthesized by coupling with a coupler in the presence of an alkali in a solvent such as dimethylformamide or dimethylsulfoxide.

Synthetic Example (Synthesis of Exemplified Pigment (1)) 180 ml of water and 37.4 ml of concentrated hydrochloric acid (0.44 mol) in a 500 ml beaker
and 26.1 g (0.0650 mol) was added, and the mixture was stirred while cooling in an ice-water bath to bring the liquid temperature to 3 ° C. Next, a solution prepared by dissolving 9.5 g (0.14 mol) of sodium nitrite in 15 ml of water was added dropwise over 25 minutes while controlling the liquid temperature within a range of 0 to 5 ° C., and after the completion of dropping, the mixture was stirred at the same temperature for 30 minutes. Carbon was added to the reaction solution and filtered to obtain a tetrazotized solution.

Next, add 1.5 liters of water to a 3 liter beaker and add 4 parts of sodium hydroxide.
After dissolving 7.3 g (1.18 mol), 36.3 g (0.138 mol) of naphthol AS (3-hydroxy-2-naphthoic acid anilide) was added and dissolved. The coupler solution was cooled to 6 ° C., and while controlling the liquid temperature at 6 to 10 ° C., the above-mentioned tetrazotized liquid was added dropwise under stirring over 30 minutes, then stirred for 2 hours, and left to stand overnight.

The reaction solution was filtered and washed with water to obtain 63.5 g of water paste in terms of solid content. Next, using 900 ml of N, N-dimethylformamide, stirring and filtration were repeated four times at room temperature. Then 900 ml
Repeatedly stirring and filtering twice with MEK, and dried under reduced pressure to obtain 53.4 g (yield 86.5%) of a purified pigment. Melting point> 300 ° C Elemental analysis Calculated value (%) Experimental value (%) C 77.1 77.3 H 4.42 4.45 N 11.79 11.81 The above is a description of a typical pigment synthesis method, but other disazo pigments represented by the general formula (1) are also used. It is synthesized in the same manner.

The film having the above-mentioned disazo pigment shows photoconductivity,
Therefore, it can be used for the photoconductive layer of the electrophotographic photosensitive member described below.

That is, in a specific example of the present invention, an electrophotographic photoreceptor is prepared by forming a film on the conductive substrate by the vacuum deposition method or by forming a film by dispersing and containing the disazo pigment in an appropriate binder. be able to.

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

The charge generation layer contains as many disazo pigments exhibiting the aforementioned photoconductivity as possible in order to obtain sufficient absorbance.
And since the generated charge carriers are efficiently transported to the interface with the charge transport layer or the interface with the conductive support,
It is preferable to use a thin film layer, for example, 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 to generate many charge carriers, and the generated carriers need to be injected into the charge transport layer without being deactivated by recombination or trapping. It is due to being.

The charge generation layer can be formed by dispersing the disazo pigment in an appropriate binder and coating the dispersion on a conductive substrate, or can be obtained by forming a vapor deposition film by a vacuum vapor deposition device.

The binder that can be used when forming the charge generation layer by coating can be selected from a wide range of insulating resins, and can be selected from organic photoconductive polymers such as poly-N-vinylcarbazole, polyvinylanthracene, and polyvinylpyrene.

Preferably, polyvinyl butyral, polyarylate (condensed polymer of bisphenol A and phthalic acid, etc.), polycarbonate, polyester, phenoxy resin, polyvinyl acetate, acrylic resin, polyacrylamide, polyamide, polyvinyl pyridine, cellulose resin, polyurethane, epoxy resin , Casein, polyvinyl alcohol, and polyvinylpyrrolidone.

The amount of the resin contained in the charge generation layer is suitably 80% by weight or less, preferably 40% by weight or less.

The solvent for dissolving these resins differs depending on the type of the resin, and is preferably selected from those which do not dissolve the charge transport layer or the undercoat layer described below.

Specific organic solvents include alcohols such as methanol, ethanol and isopropanol, acetone,
Methyl ethyl ketone, ketones such as cyclohexanone, N, N-dimethylformamide, N, amides such as 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 and trichloroethylene, or benzene, toluene, xylene, ligroin, monochlorobenzene, dichlorobenzene, etc. The aromatic hydrocarbons and the like can be used.

Coating is dip coating, spray coating, spinner coating, bead coating,
The coating can be performed using a coating method such as a Mayer bar coating method, a blade coating method, a roller coating method, or a curtain call coating method.

Drying is preferably performed by touch drying at room temperature and then heating and drying. Heat drying is performed at a temperature of 30 to 200 ° C for 5 minutes to 2 hours.
It can be performed at rest or under blast for a time in the time range.

The charge transport layer is electrically connected to the aforementioned charge generation layer, and has a function of receiving charge carriers injected from the charge generation layer in the presence of an electric field and capable of transporting these charge carriers to the surface. ing. At this time, the charge transport layer may be laminated on or below the charge generation layer.

When the charge-transporting layer is formed on the charge-generating layer: The substance that transports charge carriers in the charge-transporting layer (hereinafter referred to as charge-transporting substance) is substantially in the wavelength range of the electromagnetic wave to which the charge-generating layer is sensitive. It is preferably insensitive.
The term “electromagnetic wave” as used herein includes a broad definition of light rays including γ-rays, X-rays, ultraviolet rays, visible light rays, near infrared rays, infrared rays, far infrared rays, and the like.

When the light-sensitive wavelength region of the charge transport layer coincides with or overlaps with that of the charge generation layer, the charge carriers generated in the charge transport layer capture each other, resulting in a decrease in sensitivity.

There are electron transporting substances and hole transporting substances as charge transporting substances, and as the electron transporting substances, chloranil, tetracyanoethylene, tetracyanoquinodimethane, 2,4,5,
There are electron-withdrawing substances such as 7-tetranitro-9-fluorenone, 2,4,5,7-tetranitroxanthone, 2,4,8-trinitrothioxanthone, and those obtained by polymerizing these electron-withdrawing substances. .

Examples of the hole-transporting substance include pyrene, N-ethylcarbazole, N-methyl-N-phenylhydrazino-3-methylidene-9-ethylcarbazole, N, N-diphenylhydrazino-3-methylidene-10-ethylphenothiazine, p-diethylaminobenzaldehyde-N, N-diphenylhydrazone, p-pyrrolidinobenzaldehyde-
Hydrazones such as N, N-diphenylhydrazone, p-diethylbenzaldehyde-3-methylbenzthiazolinone-2-hydrazone, 2,5-bis (p-diethylaminophenyl) -1,3,4-oxadiazole, 1-phenyl-3- (p-diethylaminostyryl) -5- (p-
Diethylaminophenyl) pyrazolin, 1- [pyridyl (2)]-3- (p-diethylaminostyryl) -5-
(P-Diethylaminophenyl) pyrazoline, 1- [pyridyl (3)]-3- (p-diethylaminostyryl)
-5- (p-diethylaminophenyl) pyrazoline, 1
-[Pyridyl (2)]-3-((p-diethylfuminostyryl) -4-methyl-5- (p-diethylaminophenyl) pyrazoline, 1-phenyl-3- (p-diethylaminostyryl) -4-methyl- Pyrazolines such as 5- (p-diethylaminophenyl) pyrazoline and spiropyrazoline, 2- (p-diethylaminostyryl) -6
-Oxazole compounds such as diethylaminobenzoxazole, 2- (p-diethylaminophenyl) -4- (p-dimethylaminophenyl) -5- (2-chlorophenyl) oxazole, 2- (p-diethylaminostyryl) -6-diethylamino Thiazole compounds such as benzothiazole, bis (4-diethylamino-2-
Triphenylmethane compounds such as methylphenyl) -phenylmethane, 1,1-bis (4-N, N-diethylamino-2-methylphenyl) heptane, 1,1,2,2-tetrakis (4-N, N) -Dimethylamino-2-methylphenyl)
Polyarylalkanes such as ethane, triphenylamine, poly-N-vinylcarbazole, polyvinylpyrene, polyvinylanthracene, polyvinylacridine,
Examples thereof include poly-9-vinylphenylanthracene, pyrene-formaldehyde resin, ethylcarbazole-formaldehyde resin and the like.

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

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

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

Since the charge transport layer has a limit for transporting charge carriers, the film thickness cannot be increased more than necessary. Generally, it is 5 to 30μ, but a preferable range is 8 to 20μ. When forming the charge transport layer by coating, an appropriate coating method as described above can be used.

The photoconductive layer having such a laminated structure of the charge generation layer and the charge transport layer is provided on the conductive substrate. As the conductive substrate, one having conductivity itself, for example, aluminum, aluminum alloy, copper, zinc, stainless steel,
Vanadium, molybdenum, chromium, titanium, nickel,
Indium, gold, platinum, etc. are used.

In addition, a plastic having a layer formed by vacuum deposition of aluminum, aluminum alloy, indium oxide, tin oxide, indium oxide-tin oxide alloy (for example, polyethylene, polypropylene, polyvinyl chloride, polyethylene terephthalate, acrylic resin, polyfluoride). Ethylene oxide), conductive particles (for example, carbon black, silver particles, etc.) coated on plastic with a suitable binder, conductive substrates and conductive polymers obtained by impregnating plastic or paper with conductive particles. It is possible to use a plastic or the like.

An undercoat layer having a barrier function and an adhesive function can be provided between the conductive substrate and the photosensitive layer. The undercoat 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 of aluminum oxide or the like. The thickness of the undercoat layer is 0.1 to 5 µ, preferably 0.5 to 3 µ.

In the case of using a photoreceptor in which a conductive substrate, a charge transport layer and a charge generating layer are laminated in this order and the charge transporting material is an electron transporting material, it is necessary to charge the surface of the charge generating layer negatively. When exposed, the electrons generated in the charge generation layer in the exposed portion are injected into the charge transport layer, and then,
Reach the board.

On the other hand, the holes generated in the charge generation layer reach the surface, the surface potential is attenuated, and electrostatic contrast is generated between the hole and the unexposed portion.

A visible image can be obtained by developing the electrostatic latent image formed in this manner with positively charged toner.

This can be fixed directly, or can be developed and fixed after transferring the toner image to paper or a plastic film.

Further, there is a method in which an electrostatic latent image on a photoreceptor is transferred onto an insulating layer of transfer paper, developed, and fixed. The type of the developer, the developing method, and the fixing method may be any of known methods and known methods, 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 needs to be positively charged. When exposed after charging, holes generated in the charge generation layer are injected into the charge transport layer in the exposed area. And then reach the substrate. On the other hand, the electrons generated in the charge generation layer reach the surface, the surface potential is attenuated, and electrostatic contrast is generated between the electron and the unexposed portion. At the time of development, it is necessary to use the negatively chargeable toner, contrary to the case of using the electron transporting substance.

Another specific example of the present invention is an electrophotographic photosensitive member containing the disazo pigment represented by the general formula (1) in the same layer together with a charge transporting substance.
In this case, a charge transfer complex compound composed of poly-N-vinylcarbazole and trinitrofluorenone can be used in addition to the above-described charge transporting substance.

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

The pigment used in any of the electrophotographic photosensitive members is at least one selected from disazo pigments represented by the general formula (1).
Pigments, the crystalline form of which may be amorphous or crystalline. Further, if necessary, pigments having different light absorption may be used in combination to enhance the sensitivity of the photoconductor, and to obtain a panchromatic photoconductor, the general formula (1) is used.
It is also possible to use two or more kinds of disazo pigments shown in 1) or to use them in combination with a charge generating substance selected from known dyes and pigments.

The electrophotographic photoreceptor of the present invention is used not only for electrophotographic copying machines, but also for laser printers, CRT printers, and LEDs.
It can be widely used in electrophotographic applications such as printers, liquid crystal printers, and laser plate making.

[Examples] Examples 1 to 15 Aqueous ammonia solution of casein (casein
11.2 g, 1 g of ammonia water, and 222 ml of water) were applied with a Meyer bar so that the film thickness after drying would be 1.0 μm and dried.

Next, 5 g of Exemplified Pigment (1) was added to a solution of 2 g of butyral resin (butyralization degree: 63 mol%) dissolved in 95 ml of ethanol, and dispersed by a sand mill for 2 hours. This dispersion was applied on a casein layer formed previously using a Meyer bar so that the film thickness after drying was 0.5 μm, and dried to form a charge generation layer.

Then, the structural formula Hydrazone compound 5g and polymethylmethacrylate (number average molecular weight 100,000) 5g are dissolved in benzene 70ml, and this is applied on the charge generation layer with a Meyer bar so that the film thickness after drying is 12μ and dried. A charge transport layer is formed, and Example 1 is formed.
An electrophotographic photoconductor of was prepared.

Example 2 using other exemplary pigments instead of the exemplary pigment (1)
An electrophotographic photosensitive member corresponding to No. 15 was prepared in exactly the same manner.

The electrophotographic photoconductor thus prepared was corona-charged at −5 KV by a static method using an electrostatic copying paper tester (Model EPA-8100, manufactured by Kawaguchi Denki Co., Ltd.) and held in the dark for 1 second. After that, it was exposed with an illuminance of 2 lux and the charging characteristics were examined.

The charging characteristics are as follows: the surface potential (V ₀ ) and the exposure amount (E1 / E1) necessary to reduce the potential when dark-decayed for 1 second to 1/2.
2) was measured. The results are shown.

From the above results, it can be seen that each of the electrophotographic photoreceptors of the present invention has sufficient charging ability and sufficient sensitivity.

Examples 16 to 20 The electrophotographic photoreceptors prepared in Examples 1, 2, 4, 6, and 10 were used to measure the fluctuations in the light portion potential and the dark portion potential during repeated use.

Methods include a -5.6 KV corona charger, exposure optics,
The photoconductor was attached to a cylinder of an electrophotographic copying machine equipped with a developing device, a transfer charger, a static elimination exposure optical system and a cleaner. This copying machine is configured so that an image can be obtained on a transfer sheet as the cylinder is driven.

With this copying machine, the initial light-area potential and the (V _L) the dark potential (V _D), respectively -100 V, and set near -600 V, light potential after using 5,000 times and (V _L) The dark area potential (V _D ) was measured. The results are shown.

Example 21 On the charge generation layer formed in Example 1, 5 g of 2,4,7-trinitro-9-fluorenone and poly-4,4'-dioxydiphenyl-2,2-propane carbonate (molecular weight 30
5) The coating solution prepared by dissolving 5 g in 70 ml of tetrahydrofuran was coated so that the coating amount after drying was 10 g / m ^2, and dried.

The electrophotographic photoreceptor thus prepared was subjected to a charge measurement in the same manner as in Example 1. At this time, the charging polarity was +. The results are shown.

V ₀ : +590 V E1 / 2: 3.8 lux, sec Example 22 A polyvinyl alcohol film having a thickness of 0.5 μ was formed on the aluminum surface of an aluminum vapor-deposited polyethylene terephthalate film. Next, the dispersion liquid of the disazo pigment used in Example 1 was applied onto the polyvinyl alcohol layer previously formed by a Meyer bar so that the film thickness after drying was 0.5 μ, and dried to form a charge generation layer. .

Then, the structural formula Of pyrazoline compound (5 g) and polyarylate (bisphenol A and terephthalic acid-isophthalic acid condensation polymer) (5 g) dissolved in 70 ml of tetrahydrofuran are applied on the charge generation layer so that the film thickness after drying is 10 μm and dried. Then, the charge transport layer was formed. With respect to the electrophotographic photoreceptors thus prepared, the charging characteristics and the durability characteristics were evaluated in Example 1 and Example 16.
It measured by the method similar to. The results are shown.

V ₀ : -580V E1 / 2: 3.7lux, sec Endurance characteristics Initial V _D : -590V _VL : -150V After 5,000 sheets endurance V _D : -585V _VL : -150V From the above results, good sensitivity, The potential stability during durable use is also good.

Example 23 A casein ammonia aqueous solution (described above) was applied onto an aluminum plate having a thickness of 100 μm and dried to form an undercoat layer having a film thickness of 0.5 μm.

Next, 5 g of 2,4,7-trinitro-9-fluorenone and 5 g of poly-N-vinylcarbazole (number average molecular weight 300,000) were dissolved in 70 ml of tetrahydrofuran to prepare a charge transfer complex compound. 1 g of this charge transfer complex compound and the exemplified pigment (3)
5 g of polyester (trade name: Byron, Toyobo Co., Ltd.)
Was added to a liquid dissolved in 70 ml of tetrahydrofuran and dispersed. This dispersion was applied onto the subbing layer and dried to form a 12 μm layer to prepare an electrophotographic photoreceptor. The electrophotographic characteristics of this electrophotographic photosensitive member were measured by the same method as in Example 1. However, the charging polarity was +. The results are shown.

V ₀ : + 610V E1 / 2: 2.7lux, sec [Effects of the Invention] The electrophotographic photoreceptor of the present invention contains a specific disazo pigment in the photoconductive layer so that the inside of the photoconductive layer containing the disazo pigment is It is presumed that one or both of the carrier generation efficiency and the carrier transport efficiency are improved, and the electrophotographic photosensitive member has high sensitivity and excellent potential stability during durable use.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shoji Amamiya 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (56) References JP-A-60-46560 (JP, A) JP-A-60 -46562 (JP, A) JP-A-62-78561 (JP, A)

Claims (6)

(57) [Claims] An electrophotographic photosensitive member having a photoconductive layer on a conductive substrate, wherein the photoconductive layer contains a disazo pigment represented by the following general formula (1). General formula In the formula, R ₁ and R ₂ are an alkyl group, an aromatic hydrocarbon group,
Represents an aromatic heterocyclic group, the above group may have a substituent, R ₁ and R ₂ may be the same or different, and
₁ and A ₂ represent a coupler residue having a phenolic hydroxyl group, and A ₁ and A ₂ may be the same or different. _2. The electrophotographic photosensitive member according to claim 1, wherein one or both of A ₁ and A _{2 in} the general formula (1) is a coupler residue having a phenolic hydroxyl group represented by the following general formula (2). General formula In the formula, X represents a residue necessary for forming a polycyclic aromatic ring or a heterocyclic ring by being condensed with a benzene ring, and R ₃ and R ₄ represent a hydrogen atom, an alkyl group, an aryl group, an aralkyl group or a heterocyclic group. , The above groups may have a substituent, or R ₃ ,
R ₄ represents a cyclic amino group together with the nitrogen atom to be bonded. 3. The electrophotographic photosensitive member according to claim 1, wherein one or both of A ₁ and A _{2 in} the general formula (1) is a coupler residue having a phenolic hydroxyl group represented by the following general formula (3). General formula In the formula, R ₅ represents an alkyl group, an aryl group or an aralkyl group, and the above group may have a substituent. 4. The electron according to claim ₁ , wherein one or both of A ₁ and A _{2 in} the general formula (1) is a coupler residue having a phenolic hydroxyl group represented by the following general formula (4). Photoreceptor. General formula In the formula, Y represents an aromatic hydrocarbon divalent group or a heterocyclic divalent group containing a nitrogen atom in the ring. 5. The electrophotographic photosensitive member according to claim 1, wherein one or both of A ₁ and A _{2 in} the general formula (1) is a coupler residue having a phenolic hydroxyl group represented by the following general formula (5). General formula In the formula, X is a residue necessary for forming a polycyclic aromatic ring or a heterocyclic ring by being condensed with a benzene ring, R ₆ is an aryl group or a heterocyclic group, and the above group may have a substituent. . 6. The electron according to claim ₁ , wherein one or both of A ₁ and A _{2 in} the general formula (1) is a coupler residue having a phenolic hydroxyl group represented by the following general formula (6). Photoreceptor. General formula In the formula, X is a residue necessary for forming a polycyclic aromatic ring or a heterocyclic ring by being condensed with a benzene ring, R ₇ and R ₈ are alkyl groups, aryl groups, aralkyl groups or heterocyclic groups,
The above groups may have a substituent.