JPH0719064B2 - Electrophotographic photoreceptor - Google Patents

Description

TECHNICAL FIELD The present invention relates to an electrophotographic photosensitive member using a novel electrophotographic photosensitive material, more specifically, a tetrakisazo pigment having a specific molecular structure in a photoconductive layer. The present invention relates to an electrophotographic photoreceptor.

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

For example, RCA Review Vol.23, P.423 ~ P.419 (1962.9)
Has announced the photoconductivity of phthalocyanine pigments, and an electrophotographic photoreceptor using this phthalocyanine pigment has been disclosed in US Pat. No. 3397086 and US Pat.
No. 816118, for example. In addition, as an organic semiconductor used for an electrophotographic photoreceptor, for example, U.S. Pat. No. 4,315,983, U.S. Pat. No. 4,327,169 and Re
seach Disclosure 20517 (1981.5), pyrylium dyes, squaric acid methine dyes described in US Pat. No. 3824099, US Pat. No. 3898
Examples thereof include disazo pigments described in US Pat. No. 084, US Pat. No. 4,251,613 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 a conductive substrate has the advantage of improved color sensitivity, but only a few are practically applicable 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, and yet another object of the present invention is that it can be used in all existing electrophotographic processes. The present invention provides an electrophotographic photosensitive member having a high sensitivity characteristic and a stable potential characteristic in repeated use.

[Means and Actions for Solving Problems] The present invention relates to an electrophotographic photoreceptor having a photoconductive layer on a conductive substrate, wherein the photoconductive layer is (In the formula, A represents a coupler residue having a phenolic OH group, and X ₁ and X ₂ represent a hydrogen atom, a halogen atom, an optionally substituted alkyl group, an aryl group, an aralkyl group or an alkoxy group. The electrophotographic photosensitive member is characterized by containing a disazo pigment represented by

More preferable specific examples of the coupler residue represented by A in the general formula (1) are represented by the following general formulas (2) to (8).

In the formula, X is condensed with a benzene ring to form a polycyclic aromatic ring or heterocyclic ring selected from a naphthalene ring, an anthracene ring, a carbazole ring, a benzcarbazole ring, a dibenzofuran ring, a benzonaphthofuran ring and a diphenylene sulfide ring. Indicates a residue.

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

R ₁ and R ₂ are a hydrogen atom, an alkyl group which may have a substituent, an aralkyl group, an aryl group, a heterocycle or R ₁ and
A cyclic amino group is shown together with the nitrogen atom to which R ₂ is bonded.

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

In the general formulas (3) and (4), R ₃ and R ₄ represent an alkyl group which may have a substituent, an aralkyl group or an aryl group, and specific examples of these groups include R ₁ and R 4 mentioned above. The groups of the same specific examples as ₂ are mentioned.

Examples of the substituent that the alkyl group, aralkyl group, aryl group and heterocyclic group represented by R _{1 to} R _{4 in} the general formulas (2) to (4) may have include alkyl such as methyl, ethyl and propyl. Groups, alkoxy groups such as methoxy, ethoxy and propoxy, halogen atoms such as fluorine atom, chlorine atom, bromine atom and iodine atom, substituted amino groups such as nitro group, cyano group, dimethylamino, diethylamino, dibenzylamino and diphenylamino. And so on.

In the general formulas (5) and (6), Y is 2 of aromatic hydrocarbon.
A divalent group or a divalent heterocyclic group containing a nitrogen atom as a hetero atom is shown.

Examples of the divalent group of aromatic hydrocarbon include divalent groups of monocyclic aromatic hydrocarbon such as o-phenylene, condensation of o-naphthylene, perinaphthylene, 1,2-anthrylene, 9,10-phenanthrene and the like. A divalent group of polycyclic aromatic hydrocarbon can be mentioned.

Further, as a divalent group of a hetero ring containing a nitrogen atom as a hetero atom, 3,4 pyrazolediyl, 2,3-pyridindiyl, 4,5-pyrimidinediyl, 6,7-indazolediyl, 6,7- Examples thereof include 5- to 6-membered divalent groups such as quinolinediyl.

In the general formula (7), R ₅ is phenyl which may have a substituent,
An aryl group such as naphthyl, anthryl and pyrenyl or a heterocyclic group such as pyridyl, thienyl, furyl and carbazolyl is shown.

Examples of the substituent of the above groups include halogen atoms such as fluorine atom, chlorine atom, bromine atom and iodine atom, alkyl groups such as methyl, ethyl, propyl and butyl, alkoxy groups such as methoxy, ethoxy, propoxy and butoxy, and nitro group. , Cyano group, dimethylamino, diethylamino,
Substituted amino groups such as dipropylamino, dibenzylamino, diphenylamino, morpholino, piperidino, pyrrolidino and the like can be mentioned.

In the general formula (8), R ₆ and R ₇ represent an alkyl group which may have a substituent, an aralkyl group, an aryl group or a heterocycle. Specific examples of the alkyl group are methyl, ethyl, propyl and butyl groups, specific examples of the aralkyl group are benzyl, phenethyl and naphthylmethyl groups, and specific examples of the aryl group are phenyl and naphthyl groups.
Groups such as anthryl and diphenyl, and heterocyclic groups such as carbazole, dibenzofuran, benzimidazolone,
Examples thereof include groups such as benzthiazole, thiazole and pyridine. Examples of the substituent of the above group include R ₅
The same groups as the substituents in can be mentioned.

In the general formula (1), specific examples of X ₁ and X ₂ include hydrogen atom, halogen atom such as chlorine atom, bromine atom and iodine atom, alkyl group such as methyl, ethyl and butyl, phenyl, naphthyl, anthranyl and the like. It is an aryl group, an aralkyl group such as benzyl and naphthylmethyl, and an alkoxy group such as methoxy, ethoxy, and phenoxy, and these groups may have the same substituents as the substituents for R ₅ .

A general method for producing the disazo pigment used in the present invention will be described.

The pigment represented by the general formula (1) is prepared by subjecting 2,7-dinitrophenanthrenequinone and dibenzyl ketone to dehydration condensation reaction in the presence of an alkali to give 2,5-diphenyl-3,4- (4,4'-
Dinitro-o, o'-biphenylene) cyclopentadienone, which is produced by reducing the nitro group to an amino group, then tetrazotizing with sodium nitrite or nitrosyl sulfuric acid, and further azo coupling with a coupling component. You can

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

, Since only the portions A, X ₁ and X ₂ are different,
As an example of the pigment below, the structure is as follows: A part and X ₁ , X ₂
Only the part of is posted.

The disazo pigment described in the above specific examples is not limited by the description.

The film containing the above-mentioned disazo pigment shows photoconductivity,
It can be used for the photosensitive layer of the following electrophotographic photoreceptor.

That is, in a specific example of the present invention, the above-mentioned disazo pigment is formed into a film on a conductive substrate by a vacuum vapor deposition method, or the disazo pigment is dispersed and contained in an appropriate binder to form a film, thereby forming the pigment in the photoconductive layer. An electrophotographic photosensitive member containing.

In a preferred specific example, the above photoconductive coating is 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 disazo pigment as possible in order to obtain sufficient absorbance, and is a thin film layer, for example, 5 μm or less, preferably 0.01 to 1 μm, in order to shorten the range of the generated charge carrier. A thin film layer having a film thickness of

This is because most of the incident light amount is absorbed by the charge generation layer,
This is because many charge carriers are generated and it is necessary to inject the generated charge carriers into the charge transport layer without deactivating them due to recombination or trapping.

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

The binder used when forming the charge generation layer by coating can be selected from a wide range of insulating resins, and can also be selected from organic conductive polymers such as poly-N-vinylcarbazole, polyvinylanthracene and polyvinylpyrene. Preferred are polyvinyl butyral, polyarylate (polycondensate of bisphenol A and phthalic acid, etc.), polycarbonate, polyester, phenoxy resin, polyvinyl acetate, acrylic resin, polyacrylamide, polyamide, polyvinyl pyridine, cellulosic resin, urethane resin, epoxy. Insulating resins such as resin, casein, polyvinyl alcohol, and polyvinylpyrrolidone can be used.

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 differs depending on the type of the resin, and is preferably selected from those that do not dissolve the charge transport layer and the undercoat layer described later.

Specifically, methanol, ethanol, alcohols such as isopropanol, acetone, methyl ethyl ketone, ketones such as cyclohexanone, N, N-dimethylformamide, N, N-dimethylacetamide and other amides, dimethyl sulfoxide and other sulfoxides, 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, Aromatic hydrocarbons such as toluene, xylene, ligroin, monochlorobenzene and dichlorobenzene can be used.

The coating can be carried out by means such as a dip coating method, a spray coating method, a spinner coating method, a bead coating method, a Meyer bar coating method, a blade coating method, a roller coating method and a curtain coating method. Drying is preferably a method of drying by touching at room temperature and then drying by heating.
The 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 while still or under blowing air.

The charge transport layer is electrically connected to the above-mentioned charge generation layer, and has a function of receiving the charge carriers injected from the charge generation layer in the presence of an electric field and transporting these charge carriers to the surface. ing. The charge transport layer may be laminated on the charge generating layer or may be laminated thereunder.

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

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 by the charge capture layer mutually capture each other, resulting in a decrease in sensitivity.

The charge-transporting substances include electron-transporting substances and hole-transporting substances, and the electron-transporting substances include chloranil, bromoanil, tetracyanoethylene, tetracyanoquinodimethane, 2,4,7-trinitro-9-fluorenone. , 2,3,
5,7-Tetranitro-9-fluorenone, 2,4,7-trinitro-9-dicyanomethylenefluorenone, 2,4,5,7-
Examples thereof include electron-withdrawing substances such as tetranitroxanthone and 2,4,8-trinitrothioxanthone and polymers obtained by polymerizing these electron-withdrawing substances.

As the hole transporting substance, pyrene, N-ethylcarbazole, N-isopropylcarbazole, N-methyl-N
-Phenylhydrazino-3-methylidene-9-ethylcarbazole, N, N-diphenylhydrazino-3-methylidene-9-ethylcarbazole, N, N-diphenylhydrazino-3-methylidene-10-ethylphenothiazine,
N, N-diphenylhydrazino-3-methylidene-10-ethylphenoxazine, p-diethylaminobenzaldehyde-N, N-diphenylhydrazone, p-diethylaminobenzaldehyde-N-α-naphthyl-N-phenylhydrazone, p-pyrrolidino Benzaldehyde-N, N-
Diphenylhydrazone, 1,3,3-trimethylindolenine-ω-aldehyde-N, N-diphenylhydrazone, p
-Hydrazones such as diethylbenzaldehyde-3-methylbenzthiazolinone-2-hydrazone, 2,5-bis (p-diethylaminophenyl) -1,3,4-oxadiazole, 1-phenyl-3- (p -Diethylaminostyryl) -5- (p-diethylaminophenyl) pyrazoline, 1- [quinolyl (2)]-3- (p-diethylaminostyryl) -5- (p-diethylaminophenyl) pyrazoline, 1- [pyridyl (2) ] -3- (p-Diethylaminostyryl) -5- (p-diethylaminophenyl) pyrazoline, 1- [6-methoxy-pyridyl (2)]-3- (p-diethylaminostyryl) -5-
(P-Diethylaminophenyl) pyrazoline, 1- [pyridyl (3)]-3- (p-diethylaminostyryl)
-5- (p-diethylaminophenyl) pyrazoline, 1
-[Lepidil (2)]-3- (p-diethylaminostyryl) -5- (p-diethylaminophenyl) pyrazoline, 1- [pyridyl (2)]-3- (p-diethylaminostyryl) -4-methyl-5 -(P-Diethylaminophenyl) pyrazoline, 1- [pyridyl (2)]-3-
(Α-Methyl-p-diethylaminostyryl) -5-
(P-diethylaminophenyl) pyrazoline, 1-phenyl-3- (p-diethylaminostyryl) -4-methyl-5- (p-diethylaminophenyl) pyrazoline,
Pyrazolines such as 1-phenyl-3- (α-benzyl-p-diethylaminostyryl) -5- (p-diethylaminophenyl) pyrazoline and spiropyrazoline, 2-
(P-Diethylaminostyryl) -6-diethylaminobenzoxazole, 2- (p-diethylaminostyryl) -4- (p-dimethylaminophenyl) -5- (2
-Chlorophenyl) oxazole and other oxazole compounds, 2- (p-diethylaminostyryl) -6-diethylaminobenzothiazole and other thiazole compounds,
Triarylmethane compounds such as bis (4-diethylamino-2-methylphenyl) -phenylmethane, 1,1
-Bis (4-N, N-diethylamino-2-methylphenyl) heptane, polyarylalkanes such as 1,1,2,2-tetrakis (4-N, N-dimethylamino-2-methylphenyl) ethane, Examples thereof include triphenylamine, poly-N-vinylcarbazole, polyvinylpyrene, polyvinylanthracene, polyvinylacridine, poly-9-vinylphenylanthracene, pyrene-formaldehyde resin and ethylcarbazoleformaldehyde resin.

These charge transport materials 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, porsulfone, polyacrylamide, polyamide, chlorinated rubber, and other insulating materials. Resin or poly-N-vinylcarbazole,
Organic photoconductive polymers such as polyvinyl anthracene and polyvinyl pyrene can be mentioned.

Since the charge transport layer has a limit for transporting charge carriers, the film thickness cannot be increased more than necessary. Generally, the range is 5 to 30μ, but the preferred range is 8 to 20.
is μ.

When forming the charge transport layer by coating, an appropriate coating method as described above can be used.

The photosensitive layer having a laminated structure of such a charge generation layer and a charge transport layer is provided on a base (conductive base) having a conductive layer.

As the substrate having a conductive layer, one having conductivity itself, for example, aluminum, aluminum alloy, copper, zinc, stainless steel, vanadium, molybdenum, chromium, titanium, nickel, indium, gold, platinum, etc. can be used. In addition, aluminum, aluminum alloy, indium oxide, tin oxide, a plastic having a layer formed by vacuum deposition method such as indium oxide-tin oxide alloy (for example, polyethylene, polypropylene, vinyl chloride resin, polyethylene terephthalate, acrylic resin, Polyfluorinated ethylene, etc.), conductive particles (for example, carbon black, silver particles, etc.) coated on a plastic with an appropriate binder, a substrate in which conductive particles are impregnated in plastic or paper, a plastic having a conductive polymer, etc. for Rukoto can.

An undercoat layer having a barrier function and an adhesive function may be provided between the conductive layer and the photosensitive layer.

The undercoat layer is made of 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. it can.

The thickness of the undercoat layer is appropriately in the range of 0.1 to 5 µ, preferably 0.5 to 3 µ.

In the case of using a photoreceptor in which a conductive layer, a charge generation layer, and a charge transport layer are laminated in this order, when the charge transport substance is an electron transport substance, the charge transport layer surface must be positively charged. When exposed, the electrons generated in the charge generation layer in the exposed area are injected into the charge transport layer, and then reach the surface to neutralize the positive charges, causing the attenuation of the surface potential and electrostatic contrast with the unexposed area. Occurs.

A visible image can be obtained by developing the electrostatic latent image thus formed with a negatively chargeable toner. Or fix it directly,
Alternatively, the toner image can be transferred to paper or a plastic film and then developed and fixed.

After transferring the electrostatic latent image on the photoreceptor to the insulating layer of transfer paper,
A method of developing and fixing can be obtained. The type of developing agent, the developing method, and the fixing method may be selected from known agents and known methods, and are not limited to particular ones.

On the other hand, when the charge transport material is a hole transport material, it is necessary to negatively charge the surface of the charge transport layer, and when exposed after charging, holes generated in the charge generation layer are injected into the charge transport layer in the exposed area. After that, it reaches the surface to neutralize the negative charges, the surface potential is attenuated, and electrostatic contrast is generated between the surface and the unexposed portion.

At the time of development, it is necessary to use a positively chargeable toner, contrary to the case where an electron transporting substance is used.

In the case of using a photoreceptor in which a conductive layer, a charge transport layer and a charge generation layer are laminated in this order and the charge transport substance is an electron transport substance, the charge generation layer surface must be negatively charged. Upon exposure, electrons generated in the charge generation layer are injected into the charge transport layer in the exposed portion, and then reach the base.

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 holes and the unexposed portion.

A visible image can be obtained by developing the electrostatic latent image formed in this manner with positively charged toner. Or fix it directly,
Alternatively, the toner image can be transferred to paper or a plastic film and then developed and fixed.

After transferring the electrostatic latent image on the photoreceptor to the insulating layer of transfer paper,
A method of developing and fixing can be obtained. The type of developing agent, the developing method, and the fixing method may be selected from known agents and known methods, and are not limited to particular ones.

On the other hand, when the charge generating layer is made of a hole transporting substance, the surface of the charge generating layer needs to be positively charged. It is injected into the transport layer and then reaches the base.

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 a negatively chargeable toner, contrary to the case where an electron transporting substance is used.

In the electrophotographic photoreceptor of the present invention, the hydrazones, pyrazolines, oxazoles, thiazoles, triarylmethanes, polyarylalkanes,
Organic photoconductive substances such as triphenylamine and poly-N-vinylcarbazoles, zinc oxide, cadmium sulfide,
The photosensitive film may contain a disazo pigment represented by the general formula (1) as a sensitizer for an inorganic photoconductive substance such as selenium.

This photosensitive film is formed by applying the photoconductive substance and the disazo pigment together with a binder.

Further, examples of the electrophotographic photosensitive member of the present invention include an electrophotographic photosensitive member in which the specific disazo pigment is contained 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 charge transport material.

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

In any of the above-described electrophotographic photoreceptors, the pigment used contains at least one pigment selected from the disazo pigments represented by the general formula (1), and its crystal form is amorphous or crystalline. It can be of any quality.

In some cases, two or more disazo pigments represented by the general formula (1) may be combined for the purpose of increasing the sensitivity of the photoconductor by using a combination of pigments having different light absorption, and obtaining a panchromatic photoconductor. Alternatively, it can be used in combination with a charge generating substance selected from known dyes and pigments.

The electrophotographic photosensitive member of the present invention can be widely used in electrophotographic application fields such as laser printers, CRT printers, LED printers, liquid crystal printers, and laser plate making in addition to being used in electrophotographic copying machines.

[Examples] Examples 1 to 25 Aqueous ammonia solution of casein (casein 1
1.2 g, 1 g of ammonia water, 222 ml of water) were applied by a Meyer bar so that the film thickness after drying would be 1.0 μm, and dried.

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

Then, p-diethylaminobenzaldehyde-N-α
-Naphthyl-N-phenylhydrazone 5g and polymethylmethacrylate (number average molecular weight 100,000) 5g benzene 70ml
Dissolved on the charge generation layer and the film thickness after drying is 12μ
And a charge transport layer were formed by coating with a Meyer bar so as to obtain the electrophotographic photosensitive member of Example 1.

Electrophotographic photoreceptors corresponding to Examples 2 to 25 were prepared in the same manner as in Example 1 by using the pigments of the disazo pigment examples described in the section of experimental results below in place of the pigment example (1). .

The electrophotographic photosensitive member prepared above was corona-charged at -5 KV in a static system using an electrostatic copying paper tester Model SP-428 manufactured by Kawaguchi Electric Co., Ltd., and kept for 1 second in a dark place. It was exposed by looks and the charging characteristics were examined.

As the charging characteristics, the surface potential (Vo) and the exposure amount (E1 / 2) required to reduce the potential when dark-decayed for 1 second to 1/2 were measured.

Further, using the electrophotographic photosensitive members prepared in Examples 2, 3, 16 and 19, fluctuations in the light portion potential and the dark portion potential during repeated use were measured.

The measuring method was as follows: The photoreceptor was attached to a cylinder of an electrophotographic copying machine equipped with a −5 KV corona charger, an exposure optical system, a developing device, a transfer charger, a static elimination exposure optical system and a greener. This copying machine is configured so that an image can be obtained on a transfer paper as the cylinder is driven.

Initial light potential (V _L ) and dark potential (V _D ) are −10 respectively.
The light potential (V _L ) and the dark potential (V _D ) were measured after setting to around 0 V and −600 V and using 5,000 times.

Example 26 5 g of 2,4,7-trinitro-9-fluorenone and poly
Tetrahydrofuran 70 ml with 4,4'-dioxydiphenyl-2,2-propane carbonate (number average molecular weight 300,000) 5 g
The coating liquid prepared by dissolving in a solution of 10g / m ²
Was applied and dried.

The charging characteristics of the electrophotographic photosensitive member thus prepared were measured in the same manner as in Example 1. At this time, the charging polarity was set to +.
The results are shown.

Vo: + 580V E1 / 2: 5.5 lux, sec Example 27 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 liquid used in Example 1 was applied onto the above polyvinyl alcohol layer with a Meyer bar so that the film thickness after drying was 0.5 μ, and dried to form a charge generation layer.

Next, 5 g of 1- [pyridyl (2)]-3- (p-diethylaminostyryl) -5- (p-diethylaminophenyl) pyrazoline and 5 g of polyarylate (a polycondensate of bisphenol A and terephthalic acid-isophthalic acid). Was dissolved in 70 ml of tetrahydrofuran and applied on 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 produced electrophotographic photosensitive member were measured in the same manner as in Example 1.

Charging characteristics Vo: −600V E1 / 2: 4.2 lux, sec Durability characteristics As is clear from the above results, the sensitivity was good and the potential stability during durable use was also good.

Example 28 An ammonia aqueous solution of casein was applied onto an aluminum plate having a thickness of 100 μm and dried to form a 0.5 μm undercoat layer.

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 form a charge transfer complex compound.

This charge transfer complex compound and 1 g of the pigment of the above-mentioned disazo pigment example (2) were dispersed by adding 5 g of polyester (trade name: Byron, manufactured by Toyobo Co., Ltd.) to 70 ml of tetrahydrofuran.

This dispersion was applied onto the undercoat layer and dried to form a 12 μm photosensitive layer.

The charging characteristics of the electrophotographic photosensitive member thus prepared are shown in Example 1.
It measured by the method similar to. However, the charge was set to +.
The results are shown.

Vo: + 600V E1 / 2: 2.9 lux, sec Example 29 A charge transport layer and a charge generating layer having the same composition as in Example 1 were sequentially formed on the casein layer of the aluminum plate having the casein layer used in Example 28. An electrophotographic photosensitive member was prepared in the same manner as in Example 1 except that the layers were 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 +.

Vo: + 580V E1 / 2: 4.2 lux, sec Example 30 Disazo pigment Using the pigment of Example (20), an electrophotographic photosensitive member was prepared in exactly the same manner as in Example 1, and a semiconductor having an oscillation wavelength of 780 nm. Exposed by laser.

Spectral sensitivity at 780 nm: 2.8 μJ / cm ² (half exposure amount) Next, a photoconductive layer similar to the photoconductor was formed on the drum of a laser printer (LBP-CX, manufactured by Canon Inc.),
When a live-action test was conducted, a good image free from fog was obtained.

Further, even when the above test was repeated 10,000 times, similar results were obtained and remained unchanged.

Examples 31 to 34 Drum-shaped drums were prepared in the same manner as in Examples 30 except that the disazo pigments (12), (19), (25) and (31) were used in place of the disazo pigment example (20). Each of the photoconductors was prepared.

The results of measuring the spectral sensitivity at 780 nm of each electrophotographic photosensitive member are shown.

Example Pigment Example Half-exposure amount (μJ / cm ² ) 31 (12) 3.0 32 (19) 1.7 33 (25) 2.0 34 (31) 2.5 Next, when a live-copy test was conducted in the same manner as in Example 30, Each gives a fog-free image, which is 1
No change was observed after repeated 10,000 times.

[Advantages of the Invention] The electrophotographic photoreceptor of the present invention contains a specific disazo pigment in the photoconductive layer, so that either the carrier generation efficiency or the carrier transport efficiency inside the photosensitive layer containing the pigment, or It is presumed that both are improved, and an electrophotographic photoreceptor having high sensitivity and excellent potential stability during durable use can be obtained. Furthermore, a good image with high sensitivity and no fog is obtained even in the oscillation wavelength range of the semiconductor laser. It has a remarkable effect of being obtained.

Claims (9)

[Claims] 1. An electrophotographic photosensitive member having a photoconductive layer on a conductive substrate, wherein the photoconductive layer comprises: (In the formula, A represents a coupler residue having a phenolic OH group, and X ₁ and X ₂ represent a hydrogen atom, a halogen atom, an optionally substituted alkyl group, an aryl group, an aralkyl group or an alkoxy group. An electrophotographic photoreceptor containing the disazo pigment represented by the formula (1). 2. In the general formula (1), A is (In the formula, X is condensed with a benzene ring to form a naphthalene ring, anthracene ring, a carbazole ring, a benzcarbazole ring,
Represents a residue forming a polycyclic aromatic ring or a heterocycle selected from a dibenzofuran ring, a benzonaphthofuran ring and a diphenylene sulfide ring, wherein R ₁ and R ₂ represent a hydrogen atom or an alkyl group which may have a substituent. , Aralkyl group,
An aryl group, a heterocycle, or a cyclic amino group together with a nitrogen atom to which R ₁ and R ₂ are bonded). 3. In the general formula (1), A is (In the formula, R ₃ represents an alkyl group, an aralkyl group or an aryl group which may have a substituent), The electrophotographic photoreceptor according to claim 1. 4. In the general formula (1), A is The electrophotographic photoreceptor according to claim 1, wherein R ₄ represents an alkyl group, an aralkyl group or an aryl group which may have a substituent. 5. In the general formula (1), A is (Wherein Y represents a divalent group of an aromatic hydrocarbon or a divalent group of a hetero ring containing a nitrogen atom as a hetero atom), and the electrophotographic photosensitive member according to claim 1. . 6. In the general formula (1), A is (Wherein Y represents a divalent group of an aromatic hydrocarbon or a divalent group of a hetero ring containing a nitrogen atom as a hetero atom), and the electrophotographic photosensitive member according to claim 1. . 7. In the general formula (1), A is (In the formula, R ₅ is an aryl group or hetero ring which may have a substituent, X is condensed with a benzene ring to form a naphthalene ring, anthracene ring, carbazole ring, benzcarbazole ring, dibenzofuran ring, benzonaphthofuran ring, And a residue forming a polycyclic aromatic ring or a heterocycle selected from a diphenylene sulfide ring.) The electrophotographic photosensitive member according to claim 1. 8. In the general formula (1), A is (In the formula, R ₆ and R ₇ are an alkyl group which may have a substituent, an aralkyl group, an aryl group or a heterocyclic ring, X is condensed with a benzene ring to form a naphthalene ring, an anthracene ring,
A carbazole ring, a benzcarbazole ring, a dibenzofuran ring, a benzonaphthofuran ring, a diphenylene sulfide ring, or a residue forming a polycyclic aromatic ring or a heterocycle. Electrophotographic photoreceptor. 9. A conductive layer, a charge generation layer containing the tetrakisazo pigment represented by the general formula (1), and at least three layers of a charge transport layer. Claims 1, 2, and 3.
The electrophotographic photosensitive member according to item 4, item 4, item 5, item 6, item 7, or item 8.