JP2627652B2 - Electrophotographic photoreceptor - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an electrophotographic photosensitive member, and more particularly, to an electrophotographic photosensitive member containing a disazo pigment having a specific molecular structure in a photosensitive layer.

[Prior Art] Conventionally, as an electrophotographic photoreceptor, those having a photosensitive layer mainly composed of an inorganic photoconductive compound such as selenium, cadmium sulfide, and zinc oxide have been widely used.

However, these inorganic electrophotographic photoreceptors have thermal stability,
It is not always satisfactory in moisture resistance and durability.

For example, when selenium is crystallized, its characteristics as an electrophotographic photoreceptor are deteriorated, which makes it difficult to manufacture, and crystallizes due to heat, fingerprints and the like. Cadmium sulfide has problems in moisture resistance and durability, and zinc oxide has problems in smoothness, hardness and friction resistance.

Further, the photosensitive wavelength region of many inorganic electrophotographic photoconductors is limited, and various methods have been proposed to extend the photosensitive wavelength to a long wavelength region, but there are many restrictions.

On the other hand, an electrophotographic photoreceptor having a photosensitive layer containing an organic photoconductive compound as a main component has many advantages such as being easy to produce and generally having better thermal stability than selenium or the like.

In particular, a laminated type electrophotographic photoreceptor comprising a layer containing a substance that generates charges when irradiated with light (charge generation layer) and a layer containing a substance that transfers charges (charge transport layer) is a conventional organic electron-sensitive material. Some of them have been put to practical use because they generally have higher sensitivity and are more stable in chargeability than photographic photoreceptors.

For example, Japanese Patent Publication No. 50-10496, U.S. Pat.
In the specification, poly-N-vinylcarbazole and 2,4,7-
Photoreceptor having a photosensitive layer containing trinitrofluorenone-9-one, photoreceptor having a photosensitive layer containing poly-N-vinylcarbazole and 2,4,7-trinitrofluorenone-9-one, poly-N-vinyl And carbazole sensitized with a pyrylium salt dye (Japanese Patent Publication No. 48-25658).

Although these organic electrophotographic photoreceptors have improved the disadvantages of the inorganic electrophotographic photoreceptor to some extent, they are not always satisfactory in sensitivity and durability.

Various studies have been made on using organic dyes and pigments as charge generation substances. For example, JP-A-59-33445, JP-A-56-46237, and JP-A-60-200 as photosensitive members using a disazo pigment or a trisazo pigment as a charge generating substance.
JP-A-111249 is already known.

Further, as an electrophotographic photosensitive member using a phenazine pigment as a charge generating substance, for example, Japanese Patent Application Laid-Open No. Sho 62-296147 has been proposed.

However, electrophotographic photoreceptors using these disazo pigments or trisazo pigments as charge generating substances are not always satisfactory in sensitivity, residual potential or stability characteristics upon repeated use, and the selection range of the charge transporting substance. However, it does not sufficiently satisfy a wide range of requirements of the electrophotographic process.

[Problems to be Solved by the Invention] An object of the present invention is to provide a novel photoconductive material,
To provide an electrophotographic photoreceptor containing a specific disazo pigment which is stable to heat and light, and has excellent charge generating ability, has a high sensitivity and a small residual potential, and is stable when repeatedly used. An object of the present invention is to provide an electrophotographic photosensitive member having potential characteristics.

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

General formula In the formula, X represents a naphthylene group which may have a substituent, and A represents a coupler residue having a phenolic hydroxyl group.

Specifically, examples of the substituent which the naphthylene group may have in X include a halogen atom such as fluorine, chlorine, bromine and iodine, and an alkyl group such as methyl and ethyl.

More preferred specific examples of the coupler residue having a phenolic hydroxyl group represented by A include the following general formulas (2) to (2).
The residue shown by (6) is mentioned.

In the formula, Y is condensed with a benzene ring to form a naphthalene ring, an anthracene ring, a carbazole ring, a benzocarbazole ring,
A residue necessary for forming a polycyclic aromatic ring or a heterocyclic ring such as a dibenzofuran ring, a dibenzonaphthofuran ring, a diphenylene sulfide ring, and a fused ring of Y is a naphthalene ring, an anthracene ring, a carbazole ring, a benzocarbazole ring Is more preferable.

R ₁ and R ₂ are a hydrogen atom, an alkyl group which may have a substituent, an aryl group, an aralkyl group, a heterocyclic group or R ₁ ,
A cyclic amino group containing a nitrogen atom bonded to R _{2 in} the ring, an alkyl group such as methyl, ethyl, propyl, butyl, etc., an aryl group such as phenyl, diphenyl, naphthyl, anthryl, etc., an aralkyl group As a group such as benzyl, phenethyl, naphthylmethyl,
Examples of the heterocyclic group include groups such as carbazole, dibenzofuran, benzimidazolone, benzthiazole, thiazole, and pyridine.

In the formula, R ₃ represents a hydrogen atom, an alkyl group which may have a substituent, an aryl group or an aralkyl group. Specific examples of R ₃ are represented by the same example as R _1, R ₂ above.

Examples of the substituent which the alkyl group, the aryl group, the aralkyl group, the alkoxy group, and the heterocyclic group represented by R _{1 to} R ₃ in formulas (2) and (3) may have include, for example, a fluorine atom,
Halogen atoms such as chlorine atom, iodine atom and bromine atom,
Alkyl groups such as methyl, ethyl, propyl, isopropyl and butyl, alkoxy groups such as methoxy, ethoxy, propoxy and phenoxy, nitro groups, cyano groups, dimethylamino, dibenzylamino, diphenylamino, morpholino, substituted amino such as piperidino and pyrrolidino And the like.

In the formula, Z represents an aromatic hydrocarbon divalent group or a heterocyclic divalent group containing a nitrogen atom in the ring, and examples of the aromatic hydrocarbon divalent group include monocyclic aromatic groups such as o-phenylene. Divalent radicals of aromatic hydrocarbons, o-naphthylene, perinaphthylene, 1,
Examples of the divalent group of a condensed polycyclic aromatic hydrocarbon such as 2-anthrylene and 9,10-phenanthrylene, and a divalent group of a heterocyclic ring containing a nitrogen atom in the ring include 3,4-pyrazoldiyl And a divalent group such as a 2,3-pyridinediyl group, a 4,5-pyrimidinediyl group, a 6,7-indazolediyl group, and a 6,7-quinolinediyl group.

In the formula, R ₄ represents an aryl group or a heterocyclic group which may have a substituent, and specific examples include phenyl, naphthyl, anthryl, pyrenyl, pyridyl, thienyl, furyl, and carbazolyl groups.

Further, examples of the substituent of the aryl group and the heterocyclic group include 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, and phenoxy. And substituted amino groups such as alkoxy group, nitro group, cyano group, dimethylamino, dibenzylamino, diphenylamino, morpholino, piperidino and pyrrolidino.

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

In the formula, R ₅ and R ₆ represent a hydrogen atom, an alkyl group which may have a substituent, an aralkyl group, an aryl group, or a heterocyclic group, and specifically, as the alkyl group, methyl, ethyl, propyl, As butyl and aralkyl groups, benzyl, phenethyl, naphthylmethyl, aryl groups as phenyl, diphenyl, naphthyl, anthryl, and heterocyclic groups as carbazolyl, thienyl, pyridyl, furyl and the like, and further, alkyl groups, aralkyl Group, an aryl group, a substituent of the heterocyclic group, a fluorine atom, a chlorine atom, an iodine atom, a halogen atom such as a bromine atom, an alkyl group such as methyl, ethyl, propyl, isopropyl, butyl, methoxy, ethoxy, propoxy,
Alkoxy groups such as phenoxy, nitro groups, cyano groups,
Examples include substituted amino groups such as dimethylamino, dibenzylamino, diphenylamino, morpholino, piperidino, and pyrrolidino.

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

Hereinafter, typical examples of the disazo pigment represented by the general formula (1) will be listed.

However, these disazo pigments do not limit the claims of the present invention.

The description shall show only those X and A that vary in the basic form.

Illustrative pigment (1) Illustrative pigment (2) X: Same as above Illustrative pigment (3) X: Same as above Illustrative pigment (4) X: Same as above Illustrative pigment (5) X: Same as above Illustrative pigment (6) X: Same as above Illustrative pigment (7) Illustrative pigment (8) Illustrative pigment (9) Illustrative pigment (10) X: Same as above Illustrative pigment (11) X: Same as above Illustrative pigment (12) X: Same as above Illustrative pigments (13) Illustrative pigment (14) X: Same as above Illustrative pigment (15) X: Same as above Illustrative pigment (16) X: Same as above Illustrative pigment (17) X: Same as above Illustrative pigment (18) X: Same as above Illustrative pigment (19) X: Same as above Illustrative pigment (20) X: Same as above Illustrative pigment (21) X: Same as above Illustrative pigment (22) X: Same as above Illustrative pigment (23) X: Same as above Illustrative pigment (24) X: Same as above Illustrative pigment (25) X: Same as above As a general production method of the disazo pigment represented by the general formula (1), The diamine shown by using sodium nitrite or nitrosylsulfuric acid, etc., was converted into a tetrazonium salt by a conventional method and subjected to aqueous coupling with the corresponding coupler, or the obtained tetrazonium salt was taken out as a stable salt such as a borofluoride salt Thereafter, it can be easily synthesized by coupling with a corresponding coupler in a solvent such as N, N-dimethylformamide.

Synthesis Example (Synthesis of Exemplified Pigment (5)) To 7.8 g of 2,7-dinitrophenanthrenequinone and 5.0 g of 2,3-diaminonaphthalene, add 400 ml of o-dichlorobenzene and 2-3 drops of piperidine to obtain about 1 Reflux for hours. After cooling, the precipitate was collected by filtration, washed with methanol, and dried to obtain orange fine crystals. This was recrystallized from o-dichlorobenzene to obtain 10.1 g of a purified product (yield: 92%).

5.0 g of this dinitro compound was dispersed in 150 ml of a 35% hydrochloric acid aqueous solution, and 26.8 g of SnCl ₂ .2H ₂ O was added.
The mixture was heated and stirred for an hour. After cooling, the precipitate was collected by filtration, added to about 500 ml of water, and further made strongly alkaline by adding sodium hydroxide.After sufficiently stirring, the precipitate was collected by filtration again.
After washing with water and stirring, 4.1 g of a green-brown diamino compound (yield 96
%).

To 2.0 g of the obtained diamino compound, 100 ml of 20% hydrochloric acid and 60 m of water
After stirring for about 30 minutes, an aqueous solution in which 1.0 g of sodium nitrite was dissolved in 10 ml of water was gradually added dropwise while maintaining the temperature of the solution at 0 ° C. or lower. After sufficiently stirring, the deposit was collected by filtration, washed with methanol and isopropyl alcohol in that order, and dried to obtain 2.3 g (yield 74%) of a tetrazonium salt which was a precursor of the desired disazo pigment.

As a coupling component, 1.9 g was dissolved in N, N-dimethylformamide (120 ml), and while maintaining the temperature of the solution at 5 to 10 ° C., the above tetrazonium salt
1.2 g and 0.7 g of triethylamine were added and stirred for about 2 hours. After the reaction, the precipitate was collected by filtration, washed with N, N-dimethylformamide and water in that order, and dried to obtain the desired disazo pigment.

 The IR spectrum of the desired disazo pigment is shown in the drawing.

The coating containing the disazo pigment represented by the general formula (1) has photoconductivity and can be used for a photosensitive layer of an electrophotographic photoreceptor.

That is, in the present invention, an electrophotographic photoreceptor can be constituted by forming a film by dispersing and containing the disazo pigment represented by the above general formula (1) in a suitable binder on a conductive support.

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

The charge generation layer contains as much of the aforementioned photoconductive disazo pigment as possible to obtain sufficient absorbance,
Further, in order to shorten the range of the generated charge carriers, it is desirable to form a thin film layer, for example, a thin film layer having a thickness of 5 μm or less, preferably 0.01 to 1 μm.

As described above, the charge generation layer can be formed, for example, by dispersing a disazo pigment represented by the general formula (1) in a suitable binder and applying the resultant to a conductive support.

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, polyvinyl benzal, polyarylate (condensed union of bisphenol A and phthalic acid, etc.), polycarbonate, polyester, phenoxy resin, polyvinyl acetate, acrylic resin, polyacrylamide, polyamide, polyvinyl pyridine, cellulose resin, urethane Examples of the resin include insulating resins such as 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 methanol, ethanol,
Alcohols such as isopropanol, ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, dichlorohexanone, amides such as N, N-dimethylformamide, N, N-dimethylacetamide, sulfoxides such as dimethyl sulfoxide, tetrahydrofuran, dioxane , Ethers such as ethylene glycol monomethyl ether, esters such as methyl acetate and ethyl acetate, chloroform, methylene chloride, dichloroethylene, carbon tetrachloride, aliphatic halogenated hydrocarbons such as trichloroethylene or benzene, toluene,
Aromatic substances such as xylene, ligroin, monochlorobenzene, and dichlorobenzene can be used.

Coating can be performed using a coating method 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 performed by touch drying at room temperature and then heating and drying. The heating and drying can be performed at a temperature of 30 to 200 ° C. for 5 minutes to 2 hours in a still or blown state.

As the charge transport 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-pyrrolidinobenzaldehyde- N, N-diphenylhydrazone, 1,3,3-trimethylindolenine-ω-aldehyde-N, N-diphenylhydrazone, p-
Hydrazone compounds 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) pyrazolin, 1- [pyridyl (3)]-3- (p-diethylaminostyryl)
-5- (p-diethylaminophenyl) pyrazoline, 1
-[Lepidyl (2)]-3- (p-diethylaminostyryl) -5- (p-diethylaminophenyl) pyrazolin, 1- [pyridyl (2)]-3- (p-diethylaminostyryl-4-methyl-5- (P-diethylaminophenyl) pyrazolin, 1- [pyridyl (2)]-3-
(Α-methyl-p-diethylaminostyryl) -5-
(P-diethylaminophenyl) pyrazolin, 1-phenyl-3- (p-diethylaminostyryl) -4-methyl-5- (p-diethylaminophenyl) pyrazolin,
Pyrazoline compounds such as 1-phenyl-3- (α-benzyl-p-diethylaminostyryl) -5- (p-diethylaminophenyl) pyrazolin and spiropyrazolin, α-phenyl-4-N, N-diphenylaminostilbene, N- Ethyl-3- (α-phenylstyryl) carbazole, 9-p-dibenzylaminobenzylidene-9H
-Styryl compounds such as fluorenone, 5-p-ditolylaminobenzylidene-5H-dibenzo [a, b] cycloheptene, 2- (p-diethylaminostyryl) -6-
Oxazole-based compounds such as diethylaminobenzoxazole, 2- (p-diethylaminophenyl) -4- (p-dimethylaminophenyl) -5- (2-chlorophenyl) oxazole, 2- (p-diethylaminostyryl) -6-diethylaminobenzo Thiazole compounds such as thiazole, triarylmethane compounds such as bis (4-diethylamino-2-methylphenyl) phenylmethane, 1,1-bis (4-N, N-diethylamino-2)
-Methylphenyl) heptane, 1,1,2,2 tetrakis (4
Polyarylalkane compounds such as -N, N-dimethylamino-2-methylphenyl) ethane, triphenylamine, poly-N-vinylcarbazole, polyvinylpyrene, polyvinylanthracene, polyvinylacridine,
Examples thereof include poly-9-vinyl anthracene, a pyrene-formaldehyde resin, and an ethyl carbazole formaldehyde resin.

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

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 a binder include, for example, acrylic resins, polyallylates, polyesters, polycarbonates, polystyrenes, acrylonitrile-styrene copolymers, acrylonitrile-butanediene copolymers, polyvinyl butyral, polyvinyl formal, polysulfone, polyacrylamide, polyamide, chlorinated rubber and the like. Organic resin such as a conductive resin or poly-N-vinylcarbazole, polyvinylanthracene, or 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 40 μm, but a preferable range is 15 to 30 μm.
It is.

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

Such a photosensitive layer having a laminated structure of a charge generation layer and a charge transport layer is provided as a conductive support on a support having, for example, a conductive layer.

As the conductive support, the support itself has conductivity, for example, aluminum, aluminum alloy, copper, zinc, stainless steel, vanadium, molybdenum, chromium, titanium,
Nickel, indium, gold, platinum, and the like can be used. In addition, plastics having a layer in which aluminum, an aluminum alloy, indium oxide, tin oxide, indium oxide-tin oxide alloy, or the like is formed by a vacuum evaporation method can be used. For example, a support in which conductive particles (eg, carbon black, silver particles, etc.) are coated on a plastic together with a suitable binder, conductive particles, such as polyethylene, polypropylene, polyvinyl chloride, polyethylene terephthalate, acrylic resin, and polyfluoroethylene. And a support having a conductive polymer impregnated in plastic or paper.

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 casein,
Polyvinyl alcohol, nitrocellulose, ethylene-
It can be formed of acrylic acid copolymer, polyamide (nylon 6, nylon 66, nylon 610, copolymerized nylon, alkoxymethylated nylon and the like), polyurethane, gelatin, aluminum oxide and the like.

The thickness of the undercoat layer is 5 μm or less, preferably 0.1 to 3 μm.
m is appropriate.

As another specific example of the electrophotographic photoreceptor of the present invention, an electrophotographic photoreceptor in which the disazo pigment represented by the above general formula (1) is contained in the same layer together with the charge transporting material can be mentioned.

At this time, in addition to the charge transport material, a charge transfer complex compound composed of poly-N-vinylcarbazole and trinitrofluorenone can be used.

The electrophotographic photoreceptor of this example is manufactured by dispersing a disazo pigment represented by the above general formula (1) and a 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).
Contains different types of pigments.

If necessary, two or more disazo pigments represented by the above general formula (1) may be used in combination for the purpose of increasing the sensitivity of the photoreceptor by using a combination of pigments having different light absorptions and obtaining a panchromatic photoreceptor. 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 applied to various optical recording devices such as a laser beam printer and an LED printer in addition to being used for an electrophotographic copying machine.

Examples Examples 1 to 25 An undercoat layer of 0.1 μm vinyl chloride-maleic anhydride-vinyl acetate copolymer was provided on an aluminum plate.

Next, 5 g of the above exemplified pigment (1) was added to 95 ml of cyclohexanone.
Was dissolved in a solution of 2 g of butyral resin (butyralization degree: 63 mol%, number average molecular weight: 20,000), and dispersed by a sand mill for 20 hours. This dispersion was applied on a previously formed undercoat layer using a Meyer bar so that the film thickness after drying was 0.5 μm, and dried to form a charge generation layer.

Next, p-diethylaminobenzaldehyde-N-α
5 g of naphthyl-N-phenylhydrazone and 5 g of polymethyl methacrylate (number average molecular weight 100,000)
The solution was dissolved in 70 ml, and this solution was applied on a charge generation layer with a Meyer bar so that the film thickness after drying was 20 μm, and dried to form a charge transport layer. Thus, an electrophotographic photosensitive member of Example 1 was prepared.

Electrophotographic photosensitive members corresponding to Examples 2 to 25 were prepared in the same manner as in Example 1 except that the following exemplary pigment was used in place of the exemplary pigment (1) used in Example 1.

The electrophotographic photoreceptor thus prepared was corona-charged at −5.5 KV by a static method using an electrostatic copying paper tester (Model SP-428, manufactured by Kawaguchi Electric Co., Ltd.), and charged in a dark place by 1 kV.
After holding for 2 seconds, exposure was carried out at an illuminance of 2 lux, and charging characteristics were examined.

As the charging characteristics, the surface potential (V ₀ ) and the exposure amount (E1 / 2) required to attenuate the potential after dark decay for one second to half were measured. The results are shown.

Comparative Example In place of the exemplary pigment (5) used in Example 5,
A photoconductor was prepared and evaluated in exactly the same manner as in Example 5, except that an azo pigment represented by the following structural formula described in JP-A-296147 was used. The results are shown.

V ₀ : −775 V E1 / 2: 8.2 lux, sec From these results, it can be seen that all the electrophotographic photosensitive members of the present invention have excellent sensitivity.

Examples 26 to 28 Using the electrophotographic photosensitive members prepared in Examples 5, 6, and 18,
Fluctuations in the light potential and dark potential during repeated use were measured.

The measurement method is -5.6 KV corona charger, exposure optical system,
The photoreceptor was affixed to a cylinder of an electrophotographic copying machine equipped with a developing unit, a transfer charger, a charge erasing exposure optical system and a cleaner. This copying machine is configured so that an image can be obtained on a transfer paper by driving a cylinder.

Using this copier, the initial light potential (V _L ) and dark potential (V _D ) were set at around -200 V and -700 V, respectively, and 5,
The light potential (V _L ) and dark potential (V _D ) after 000 use were measured. The results are shown.

From the above results, it can be seen that the sensitivity is good and the potential stability during durable use is also good.

Example 29 Soluble nylon (6-66) was placed on an aluminum plate having a thickness of 100 μm.
A methanol solution of -610-12 quaternary nylon copolymer) was applied and dried to form a 0.5 μm-thick 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.

1 g of this charge-transfer complex compound and Exemplified Pigment (5) was mixed with a polymethyl methacrylate-styrene copolymer (molecular weight 250,000).
5 g was added to a solution dissolved in 70 ml of tetrahydrofuran and dispersed. The thickness of this dispersion after drying on the undercoat layer is 20 μm.
And dried.

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

V ₀ : +705 V E1 / 2: 4.5 lux, sec [Effect of the Invention] The electrophotographic photoreceptor of the present invention uses a specific disazo pigment for the photosensitive layer, and thus, the carrier generation efficiency or the carrier transport inside the photosensitive layer. It is presumed that one or both of the efficiencies are improved, and as a result, the electrophotographic photoreceptor is highly sensitive and durable, and particularly excellent in potential stability during durable use.

[Brief description of the drawings]

The figure shows the IR spectrum of the exemplary pigment (5) in the synthesis example.

Continuation of the front page (56) References JP-A-62-296147 (JP, A) JP-A-63-284555 (JP, A) JP-A-64-57265 (JP, A) JP-A 64-2054 (JP, A) JP-A-1-224770 (JP, A) JP-A-62-296147 (JP, A) JP-A-1-142727 (JP, A)

Claims (1)

(57) [Claims] An electrophotographic photosensitive member having a photosensitive layer on a conductive support, wherein the photosensitive layer contains a disazo pigment represented by the following general formula (1). General formula In the formula, X represents a naphthylene group which may have a substituent,
A represents a coupler residue having a phenolic hydroxyl group.