JP2739375B2 - Electrophotographic photoreceptor, electrophotographic apparatus provided with the electrophotographic photoreceptor, and facsimile - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an electrophotographic photoreceptor, and more particularly, to an electrophotographic photoreceptor having a photosensitive layer containing a disazo pigment having a specific structure, and an electrophotographic photoreceptor. The present invention relates to an electrophotographic apparatus and a facsimile provided.

[Prior Art] Conventionally, inorganic photoconductive materials such as selenium, cadmium sulfide, and zinc oxide have been widely used as electrophotographic photoreceptors.

On the other hand, as an electrophotographic photoreceptor made of an organic photoconductive substance, a photoconductive polymer represented by poly-N-vinylcarbazole or 2,5-bis (p-diethylaminophenyl) -1,3,4-oxadiene Known are those using a low-molecular organic photoconductive substance such as azole, and those combining such an organic photoconductive substance with various dyes and pigments.

An electrophotographic photoreceptor using an organic photoconductive substance has a good film-forming property and can be produced by coating, and thus has an advantage that an inexpensive photoreceptor with extremely high productivity can be provided. Also,
It has the advantage that the color sensitivity can be freely controlled by selecting the dye or pigment to be used, and a wide range of studies have been made so far. Particularly recently, with the development of a function-separated type photoreceptor in which a charge generation layer containing an organic photoconductive dye or pigment and a charge transport layer containing the aforementioned photoconductive polymer or low molecular organic photoconductive substance are laminated. Significant improvements have been made in sensitivity and durability, which have been disadvantages of conventional organic electrophotographic photosensitive members.

Azo pigments exhibit excellent photoconductivity, and since compounds having various properties can be easily obtained by combining an amine component and a coupler component, a large number of compounds have been proposed so far. JP-A-54-22834, JP-A-56-116040, JP-A-58-70232, JP-A-60-11539, JP-A-61-215556, and JP-A-61-215556 It is already known in, for example, JP-A-241763 and JP-A-63-158561.

However, conventional electrophotographic photoreceptors using disazo pigments are not necessarily sufficient in terms of sensitivity and potential stability when repeatedly used, and only a few materials have been put to practical use. is there.

[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 having practical high sensitivity characteristics and stable potential characteristics in repeated use, and to provide an electrophotographic apparatus and a facsimile provided with the electrophotographic photosensitive member.

[Means for Solving the Problems and Action] The present invention comprises an electrophotographic photosensitive member having a photosensitive layer containing a disazo pigment represented by the following general formula (1) on a conductive support.

General formula In the formula, Ar ₁ and Ar ₂ are the same or different, and each represents a carbocyclic aromatic group or a heterocyclic aromatic group which may have a substituent, and R ₁ and R ₂ represent a hydrogen atom, an alkyl group or a cyano aromatic group. A ₁ and A ₂ are the same or different and represent a coupler residue having a phenolic hydroxyl group.

Ar ₁ and Ar ₂ are specifically a group obtained by removing two hydrogen atoms from a carbocyclic aromatic ring such as benzene, naphthalene, and anthracene; or a heterocyclic aromatic ring such as furan, pyrrolecarboxylic acid, thiophene, pyridine, and pyrazine. A group in which two hydrogen atoms have been removed from the aromatic ring; examples of the substituent include halogen atoms such as fluorine, chlorine, iodine and bromine, methyl,
Ethyl, propyl, isopropyl, alkyl groups such as butyl, methoxy, ethoxy, alkoxy groups such as propoxy, aryloxy groups such as phenoxy, nitro group,
Examples include an amino group which may have a substituent such as a cyano group, dimethylamino, dibenzylamino, diphenylamino, morpholino, piperidino, pyrrolidino and the like.

R ₁ , R ₂ as an alkyl group as methyl, ethyl,
And groups such as propyl.

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

X in the general formulas (2), (3) and (4) is a naphthalene ring, an anthracene ring, a carbazole ring, a benzocarbazole ring which may be substituted with a benzene ring,
It represents a residue necessary for forming a polycyclic aromatic ring such as a dibenzofuran ring or a heterocyclic ring.

Y in the general formula (6) represents a divalent aromatic hydrocarbon group which may have a substituent or a divalent heterocyclic group containing a nitrogen atom in a ring, and specifically, o-phenylene, divalent such as o-naphthylene, perinaphthylene, 1,2-anthrylene, 3,4-pyrazoldiyl, 2,3-pyridinediyl, 4,5-pyridinediyl, 6,7-indazolediyl, 6,7-quinolindiyl Groups.

R ₃ and R _{4 in the} general formulas (2) and (3) represent a hydrogen atom, an alkyl group which may have a substituent, an aryl group, an aralkyl group or a heterocyclic group, and R ₃ and R ₄ And may be combined with a nitrogen atom to form a cyclic amino group containing a nitrogen atom in the ring.

R ₅ in the general formula (4) represents a hydrogen atom, an alkyl group which may have a substituent, an aryl group, an aralkyl group or a heterocyclic group.

R ₆ in the general formula (5) represents a hydrogen atom, an alkyl group which may have a substituent, an aryl group, an aralkyl group or a heterocyclic group.

Examples of the alkyl group in the above expression include groups such as methyl, ethyl and propyl, and specific examples of the aryl group include phenyl and
Groups such as naphthyl and anthryl, aralkyl groups such as benzyl and phenethyl, and heterocyclic groups such as pyridyl, thienyl, carbazolyl, benzimidazolyl,
Examples of groups such as benzothiazolyl and cyclic amino groups containing a nitrogen atom in the ring include pyrrole, pyrroline, pyrrolidine, pyrrolidone, indole, indoline, carbazole, imidazole, pyrazole, pyrazoline, oxazine, phenoxazine and the like.

Further, as a substituent, fluorine, chlorine, iodine, halogen atoms such as bromine, methyl, ethyl, alkyl groups such as propyl, methoxy, alkoxy groups such as ethoxy, dimethylamino, alkylamino groups such as diethylamino, phenylcarbamoyl group, Examples include a nitro group, a cyano group, and a halomethyl group such as trifluoromethyl.

Z in the general formula (2) represents an oxygen atom or a sulfur atom, and n represents 0 or 1.

In the disazo pigment represented by the general formula (1), in the formula, A ₁ and A ₂ are each a general formula (2), (3) or (4), and X is condensed with a benzene ring to form a benzocarbazole ring. Pigments using the couplers described above are also suitable as charge generation materials for semiconductor lasers because their absorption range extends to near the infrared region.

Hereinafter, typical specific examples of the disazo pigment represented by the general formula (1) of the present invention are listed, but the disazo pigment used in the present invention is not limited thereto.

In the basic pigment, the specific structure is represented by describing only the changed portion in the basic type.

Basic type Illustrative pigment (1) R ₁ , R ₂ : hydrogen atom Exemplified pigment (2) Ar ₁ , Ar ₂ : same as exemplified pigment (1) R ₁ , R ₂ : same as exemplified pigment (1) exemplified pigment (3) R ₁ , R ₂ : —CN Exemplified pigment (4) Ar ₁ , Ar ₂ : same as exemplified pigment (1) R ₁ , R ₂ : same as exemplified pigment (1) exemplified pigment (5) Ar ₁ , Ar ₂ : the same as the exemplified pigment (1) R ₁ , R ₂ : —CH ₃ exemplified pigment (6) Ar ₁ , Ar ₂ : same as example pigment (1) R ₁ , R ₂ : same as example pigment (5) example pigment (7) R ₁ and R ₂ : the same as the exemplary pigment (1), the exemplary pigment (8) R ₁ , R ₂ : same as the exemplary pigment (1), the exemplary pigment (9) Ar ₁ , Ar ₂ : same as the exemplary pigment (1) R ₁ , R ₂ : same as the exemplary pigment (1) exemplary pigment (10) R ₁ , R ₂ : same as the exemplary pigment (1), the exemplary pigment (11) R ₁ , R ₂ : same as the exemplary pigment (1), the exemplary pigment (12) R ₁ , R ₂ : —C ₂ H ₅ Exemplified pigment (13) Ar ₁ , Ar ₂ : same as example pigment (1) R ₁ , R ₂ : same as example pigment (1) example pigment (14) Ar ₁ , Ar ₂ : same as exemplified pigment (1) R ₁ , R ₂ : same as exemplified pigment (1) exemplified pigment (15) Ar ₁ , Ar ₂ : same as example pigment (1) R ₁ , R ₂ : same as example pigment (1) example pigment (16) Ar ₁ , Ar ₂ : R ₁ , R ₂ : Same as the exemplary pigment (1) Exemplary pigment (17) Ar ₁ , Ar ₂ : same as the exemplary pigment (1) R ₁ , R ₂ : same as the exemplary pigment (1) exemplary pigment (18) Ar ₁ , Ar ₂ : same as exemplified pigment (1) R ₁ , R ₂ : same as exemplified pigment (3) exemplified pigment (19) R ₁ , R ₂ : same as the exemplary pigment (1), the exemplary pigment (20) Ar ₁ , Ar ₂ : same as exemplified pigment (19) R ₁ , R ₂ : same as exemplified pigment (3) exemplified pigment (21) R ₁ , R ₂ : the same as the exemplified pigment (1), the exemplified pigment (22) Ar ₁ , Ar ₂ : same as exemplified pigment (1) R ₁ , R ₂ : same as exemplified pigment (1) exemplified pigment (23) Ar ₁ , Ar ₂ : same as exemplified pigment (1) R ₁ , R ₂ : same as exemplified pigment (3) exemplified pigment (24) Ar ₁ , Ar ₂ : same as example pigment (1) R ₁ , R ₂ : same as example pigment (1) example pigment (25) Ar ₁ , Ar ₂ : same as example pigment (1) R ₁ , R ₂ : same as example pigment (1) example pigment (26) Ar ₁ , Ar ₂ : same as exemplified pigment (1) R ₁ , R ₂ : same as exemplified pigment (1) exemplified pigment (27) Ar ₁ , Ar ₂ : same as exemplified pigment (1) R ₁ , R ₂ : same as exemplified pigment (1) exemplified pigment (28) Ar ₁ , Ar ₂ : same as exemplified pigment (1) R ₁ , R ₂ : same as exemplified pigment (1) exemplified pigment (29) Ar ₁ , Ar ₂ : same as exemplified pigment (1) R ₁ , R ₂ : same as exemplified pigment (3) exemplified pigment (30) Ar ₁ , Ar ₂ : same as example pigment (1) R ₁ , R ₂ : same as example pigment (1) example pigment (31) Ar ₁ , Ar ₂ : same as example pigment (1) R ₁ , R ₂ : same as example pigment (1) example pigment (32) Ar ₁ , Ar ₂ : same as exemplified pigment (1) R ₁ , R ₂ : same as exemplified pigment (1) exemplified pigment (33) Ar ₁ , Ar ₂ : same as exemplified pigment (1) R ₁ , R ₂ : same as exemplified pigment (1) exemplified pigment (34) Ar ₁ , Ar ₂ : same as exemplified pigment (1) R ₁ , R ₂ : same as exemplified pigment (5) exemplified pigment (35) Ar ₁ , Ar ₂ : same as exemplified pigment (1) R ₁ , R ₂ : same as exemplified pigment (5) exemplified pigment (36) Ar ₁ , Ar ₂ : same as exemplified pigment (1) R ₁ , R ₂ : same as exemplified pigment (1) exemplified pigment (37) Ar ₁ , Ar ₂ : same as exemplified pigment (1) R ₁ , R ₂ : same as exemplified pigment (1) exemplified pigment (38) Ar ₁ , Ar ₂ : same as exemplified pigment (1) R ₁ , R ₂ : same as exemplified pigment (1) exemplified pigment (39) R ₁ , R ₂ : same as the exemplary pigment (3), the exemplary pigment (40) Ar ₁ , Ar ₂ : the same as the exemplary pigment (1) R ₁ , R ₂ : the same as the exemplary pigment (1) The disazo pigment represented by the general formula (1) is obtained by subjecting the corresponding diamine to tetrazotization by a conventional method and the presence of an alkali. After coupling with a lower coupler and an aqueous system, or after converting a tetrazonium salt to a borofluoride salt or a zinc chloride double salt, sodium acetate, triethylamine, N-methyl in an organic solvent such as N, N-dimethylformamide, dimethyl sulfoxide. It can be easily synthesized by coupling with a coupler in the presence of a base such as morpholine.

When synthesizing a disazo pigment in which A ₁ and A ₂ in the general formula (1) are different coupler residual groups, one mole of one coupler is firstly coupled to 1 mol of the above-mentioned tetrazonium salt, and then the other. One mole of one coupler is coupled for synthesis, or one amino group of the diamine is protected with an acetyl group and the like is diazotized, and the other coupler is coupled. To diazotize it again and couple it with a coupler to synthesize it.

Synthesis Example (Synthesis of Illustrative Pigment (2)) In a 300 ml beaker, add 150 ml of water and 20 ml of concentrated hydrochloric acid (0.23 mol) 13.45 g (0.032 mol) was added, the mixture was cooled to 0 ° C., and a solution prepared by dissolving 4.6 g (0.067 mol) of sodium nitrite in 10 ml of water was dropped into the liquid over 10 minutes while keeping the liquid temperature at 5 ° C. or lower. After stirring for 15 minutes, the mixture was filtered with carbon, and sodium borofluoride was poured into the mixture.
A solution obtained by dissolving 10.5 g (0.096 mol) in 90 ml of water was added dropwise with stirring, and the precipitated borofluoride was collected by filtration, washed with cold water, washed with acetonitrile, and dried under reduced pressure.

13.11 g, 66.3% yield N, N-dimethylformamide (DM
F) 500ml After dissolving 11.06 g (0.042 mol) and cooling the liquid temperature to 5 ° C., dissolve 12.36 g (0.020 mol) of the previously obtained borofluoride, and then drop 5.1 g (0.050 mol) of triethylamine in 5 minutes. . After stirring for 2 hours, the precipitated pigment was collected by filtration, washed four times with DMF and three times with water, and then freeze-dried.

Yield: 16.47 g, 85.0% Yield Elemental analysis Calculated value (%) Actual value (%) C 74.37 74.40 H 3.74 3.80 N 8.67 8.64 The electrophotographic photoreceptor of the present invention is prepared by applying the general formula (1) on a conductive support. Having a photosensitive layer containing the disazo pigment shown.
The form of the photosensitive layer may be any known form, but the photosensitive layer containing the disazo pigment represented by the general formula (1) is used as a charge generation layer, and the charge generation layer containing a charge transport material is used as the charge generation layer. A laminated function-separated type photosensitive layer is particularly preferred.

The charge generation layer can be formed by applying a coating solution obtained by dispersing the above disazo pigment together with a binder resin in an appropriate solvent onto a conductive support by a known method, and having a thickness of, for example, 5 μm. Below, preferably
It is desirable to form a thin film layer having a thickness of 0.1 to 1 μm.

The binder resin used at this time is selected from a wide range of insulating resins or organic photoconductive polymers. And the like, and the amount used is determined by the content in the charge generation layer.
It is at most 80% by weight, preferably at most 40% by weight.

The solvent used is preferably selected from those which dissolve the resin and do not dissolve the charge transport layer and the undercoat layer described below.

Specifically, tetrahydrofuran, ethers such as 1,4-dioxane, cyclohexanone, ketones such as methyl ethyl ketone, amides such as N, N-dimethylformamide, methyl acetate, esters such as ethyl acetate, toluene, xylene, Examples include aromatics such as chlorobenzene, alcohols such as methanol, ethanol, and 2-propanol; and aliphatic halogenated hydrocarbons such as chloroform, methylene chloride, dichloroethylene, carbon tetrachloride, and trichloroethylene.

The charge transport layer is stacked on or below the charge generation layer, and has a function of receiving charge carriers from the charge generation layer in the presence of an electric field and transporting the carriers.

The charge transporting layer is formed by dissolving a charge transporting material in a solvent together with a suitable binder resin if necessary, and applying the solution. The thickness of the charge transporting layer is generally 5 to 40 μm.
-30 μm is preferred.

The charge transporting substance includes an electron transporting substance and a hole transporting substance. Examples of the electron transporting substance include 2,4,7-trinitrofluorenone, 2,4,5,7-tetranitrofluorenone, chloranil, and tetralane. Examples thereof include electron-withdrawing substances such as cyanoquinodimethane, and those obtained by polymerizing these electron-withdrawing substances.

Examples of the hole transporting substance include polycyclic aromatic compounds such as pyrene and anthracene, carbazole-based, indole-based, imidazole-based, oxazole-based, thiazole-based, oxadiazole-based, pyrazole-based, pyrazoline-based, thiadiazole-based, and triazole-based compounds. Heterocyclic compounds such as
hydrazone compounds such as p-diethylaminobenzaldehyde-N, N-diphenylhydrazone, N, N-diphenylhydrazino-3-methylidene-9-ethylcarbazole, α-phenyl-4′-N, N-diphenylaminostilbene, 5 Styryl compounds such as-(4- (di-p-tolylamino) benzylidene] -5H-dibenzo [a, d] cycloheptene; benzidine compounds; triarylmethane compounds; triphenylamine; (E.g., poly-N-vinylcarbazole, polyvinylanthracene, etc.) having a polymer in the main chain or side chain.

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, an appropriate binder can be used. Specifically, insulating resins such as acrylic resin, polyarylate, polyester, polycarbonate, polystyrene, acrylonitrile-styrene copolymer, polyacrylamide, polyamide, and chlorinated rubber; or organic photoconductive materials such as poly-N-vinylcarbazole and polyvinylanthracene And the like.

As the conductive support on which the photosensitive layer is formed, for example, aluminum, aluminum alloy, copper, zinc conductor, stainless steel, vanadium, molybdenum, chromium, titanium, nickel, indium, gold, platinum and the like are used. In addition, a plastic (eg, polyethylene, polypropylene, polyvinyl chloride, polyethylene terephthalate, acrylic resin, etc.) obtained by forming a film of such a metal or alloy by a vacuum evaporation method, or conductive particles (eg, carbon black, silver particles, etc.) with an appropriate binder A support coated on a plastic or metal substrate together with a resin, a support in which conductive particles are impregnated in plastic or paper, or the like can be used.

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

The undercoat layer can be formed of casein, polyvinyl alcohol, nitrocellulose, polyamide (nylon 6, nylon 66, nylon 610, copolymer nylon, alkoxymethylated nylon, etc.), polyurethane, aluminum oxide, or 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 present invention, an electrophotographic photosensitive member in which the above-mentioned disazo pigment and a charge transporting substance are contained in the same layer can be mentioned. At this time, poly-N is used as a charge transport material.
A charge transfer complex consisting of vinylcarbazole and trinitrofluorenone can also be used.

The electrophotographic photoreceptor of this example can be formed by applying and drying a liquid in which the above-mentioned disazo pigment and the charge transfer complex are dispersed in an appropriate resin solution.

The pigment used in any of the electrophotographic photoreceptors may be amorphous or crystalline in the form of the disazo pigment represented by the general formula (1). Combination of two or more disazo pigments shown
It is also possible to use in combination with a known charge generating substance.

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

Next, an electrophotographic apparatus and a facsimile provided with the electrophotographic photosensitive member of the present invention will be described.

FIG. 1 shows a schematic configuration of a general transfer type electrophotographic apparatus using the drum type photoreceptor of the present invention.

In FIG. 1, reference numeral 1 denotes a drum-type photosensitive member as an image carrier, which is driven to rotate at a predetermined peripheral speed in the direction of an arrow around a shaft 1a. The photoreceptor 1 is uniformly charged at a predetermined positive or negative potential on its peripheral surface by a charging means 2 during the rotation process, and then exposed at a light exposure section 3 by an image exposure means (not shown) at an exposure section 3.
(Slit exposure, laser beam scanning exposure, etc.).

As a result, an electrostatic latent image corresponding to the exposure image is sequentially formed on the peripheral surface of the photoconductor.

The electrostatic latent image is then developed with toner by a developing unit 4, and the developed toner image is transferred by a transfer unit 5 between a photosensitive unit 1 and a transfer unit 5 from a paper supply unit (not shown) in synchronization with the rotation of the photosensitive unit 1. It is sequentially transferred onto the surface of the transfer material P taken and fed.

The transfer material P having undergone the image transfer is separated from the photoreceptor surface, introduced into the image fixing means 8 and subjected to image fixing, and is printed out as a copy (copy) outside the machine.

The surface of the photoreceptor 1 after the image transfer is cleaned and cleaned by removing the untransferred toner by the cleaning unit 6, subjected to a charge removal process by the pre-exposure unit 7, and used repeatedly for image formation. As the uniform charging means 2 for the photoreceptor 1, a corona charging device is generally widely used. Also, the corona transfer means is generally widely used for the transfer device 5.

As an electrophotographic apparatus, a plurality of components such as the above-described photoreceptor, developing means, and cleaning means are integrally connected as an apparatus unit, and this unit is configured to be detachable from the apparatus body. May be. For example,
The photoreceptor 1 and the cleaning means 6 may be integrated into one apparatus unit, and may be configured to be detachable using guide means such as rails of the apparatus body. At this time, the above-described device unit may be provided with a charging unit and / or a developing unit.

In the case where the electrophotographic apparatus is used as a copier or a printer, the light image exposure L is performed by reflecting or transmitting light from the original, or by reading the original and converting it into a signal. This is performed by driving an array or driving a liquid crystal shutter array.

When used as a facsimile printer, the light image exposure L is an exposure for printing received data.

FIG. 2 is a block diagram showing one example of this case.

The controller 10 controls the image reading unit 9 and the printer 18.

The whole of the controller 10 is controlled by the CPU 16.

The read data from the image reading unit is transmitted to the partner station through the transmission circuit 12. Data received from the partner station is sent to the printer 18 through the receiving circuit 11. Predetermined image data is stored in the image memory. The printer controller 17 controls the printer 18. 13 is a telephone.

An image received from the line 14 (image information from a remote terminal connected via the line) is demodulated by the receiving circuit 11, and then the CPU 16 performs signal processing of the image information and is sequentially stored in the image memory 15. . When the image of at least one page is stored in the memory 15, the image of the page is stored. The CPU 16 reads out one page of image information from the memory 15 and sends out one page of image information signaled to the printer controller 17.

Upon receiving one-page image information from the CUP 16, the printer controller 17 controls the printer 18 to record image information of the page.

Note that the CPU 16 is receiving the next page during recording by the printer 18.

 As described above, image reception and recording are performed.

[Examples] Examples 1 to 15 A solution prepared by dissolving 5 g of methoxymethylated nylon (weight average molecular weight: 100,000) and 10 g of alcohol-soluble copolymerized nylon (weight average molecular weight: 80,000) in 90 g of methanol on an aluminum substrate using a Meyer bar. An undercoat layer having a thickness of 1 μm after coating and drying was formed.

Next, 5 g of Exemplified Pigment (2) was added to a solution of 2 g of butyral resin (degree of butyralization: 70 mol%) in 90 g of cyclohexanone, and dispersed in a sand mill for 24 hours. The thickness of the dispersion after drying is 0.15 μm on the undercoat layer formed earlier.
Was applied with a Meyer bar and dried to form a charge generation layer.

Next, 10 g of a fluorene compound represented by the following structural formula And 9 g of bisphenol-type polycarbonate (weight average molecular weight: 50,000) are dissolved in 70 g of chlorobenzene, and this is coated on a charge generation layer with a Meyer bar so that the film thickness after drying is 17 μm, and dried to form a charge transport layer. The electrophotographic photoreceptor of Example 1 was formed.

Electrophotographic photoreceptors corresponding to Examples 2 to 15 were prepared in exactly the same manner, using the other exemplary pigments instead of the exemplary pigment (2).

The prepared electrophotographic photosensitive member was negatively charged by a corona discharge of -5 KV using an electrostatic copying paper tester Model SP-428 manufactured by Kawaguchi Electric Co., Ltd., and held for 1 second in a dark place. It was exposed at an illuminance of 17 lux, and the charging characteristics were examined.

As the charging characteristics, the surface potential (V _O ) and the exposure amount (E1 / 2) required for the surface potential after being left in a dark place to attenuate to half were measured. The results are shown.

Comparative Examples 1 to 6 Except that the disazo pigment used in Example 1 was replaced with Comparative Pigments (A) to (F) represented by the following structural formulas, an electrophotographic photoreceptor was prepared in exactly the same manner as in Example 1. Similarly, the charging characteristics were evaluated. The results are shown.

From these results, it can be seen that the electrophotographic photoreceptor of the present invention has sufficient charging ability and excellent sensitivity.

Examples 16 to 30 The electrophotographic photosensitive member prepared in Example 1 was replaced with a cylinder of an electrophotographic copying machine equipped with a -6.5 KV corona charger, an exposure optical system, a developing device, a transfer charger, a charge-removing exposure optical system, and a cleaner. Pasted in.

Initial dark potential V _D and the light portion potential V _L respectively -700 V, 20
The voltage was set near 0 V, and the amount of change in the dark area potential (ΔV _D ) and the amount of change in the light area potential (ΔV _L ) were measured after repeated use of 5,000 times.

The electrophotographic photosensitive members prepared in Examples 2 to 15 were similarly evaluated. The results are shown.

Note that a negative sign in the fluctuation amount of the potential indicates a decrease in the absolute value of the potential, and a positive sign indicates an increase in the absolute value of the potential.

Comparative Examples 7 to 12 The amount of potential change when the electrophotographic photosensitive members prepared in Comparative Examples 1 to 6 were repeatedly used in the same manner as in Example 16 was measured. The results are shown.

From the above results, it can be seen that the electrophotographic photoreceptor of the present invention has a small potential fluctuation upon repeated use.

Example 31 An undercoat layer of polyvinyl alcohol having a thickness of 0.5 μm was formed on an aluminum surface of an aluminum-deposited polyethylene terephthalate film. The dispersion liquid of the disazo pigment used in Example 4 was coated thereon with a Meyer bar and dried to form a film having a thickness of 0.2 μm.
m of the charge generation layer was formed.

Then with a styryl compound 10g of the following structural formula A solution prepared by dissolving 9.5 g of polycarbonate (weight average molecular weight: 50,000) in 80 g of tetrahydrofuran was applied on the charge generation layer and dried to form a charge transport layer having a thickness of 16 μm.

The charging characteristics and durability characteristics of the prepared electrophotographic photosensitive member were measured by the same methods as in Examples 1 and 16. The results are shown.

V _O : −700 V E1 / 2: 0.90 lux · sec ΔV _D : +4 V ΔV _L : 0 V Example 32 Electrons obtained by applying the charge generation layer and the charge transport layer of the electrophotographic photosensitive member prepared in Example 23 in reverse order. A photoreceptor was prepared, and the charging characteristics were evaluated in the same manner as in Example 1. However, the charging was positive.

V _O : + 695V E1 / 2: 1.5lux · sec Example 33 5g of 3,5-dimethyl-3 ′, 5′-di-tert-butyldiphenoquinone and polycarbonate were placed on the charge generation layer prepared in Example 15. A solution prepared by dissolving 5 g of resin (weight average molecular weight: 45,000) in 40 g of a chlorobenzene (65 parts by weight) -N, N-dimethylformamide (35 parts by weight) solution is applied by a Meyer bar and dried, and a charge having a thickness of 15 μm is formed. A transport layer was formed.

The charging characteristics of the produced electrophotographic photosensitive member were evaluated in the same manner as in Example 1. However, the charging was positive.

V _O : + 694V E1 / 2: 3.7lux · sec Example 34 0.5 g of Exemplified Pigment (22) was dispersed together with 9.5 g of cyclohexanone in a paint shaker for 5 hours. Example 1 here
A solution prepared by dissolving 5 g of the charge transporting material used in the above and 5 g of the polycarbonate resin in 40 g of tetrahydrofuran was added thereto, and further shaken for 1 hour. The coating solution thus prepared was applied to an aluminum substrate with a Meyer bar and dried to form a photosensitive layer having a thickness of 18 μm.

The charging characteristics of the produced electrophotographic photosensitive member were evaluated in the same manner as in Example 1. The charging was positive.

V _O : + 694V E1 / 2: 4.9lux · sec [Effect of the Invention] The electrophotographic photoreceptor of the present invention uses a disazo pigment having a specific structure in the photosensitive layer, so that charge carrier generation efficiency or charge carrier generation in the photosensitive layer is achieved. Either one or both of the injection efficiencies are improved, and a remarkable effect is obtained that characteristics excellent in sensitivity and potential stability during repeated use are obtained.

Similar effects can be obtained when the electrophotographic photosensitive member is used in an electrophotographic apparatus and a facsimile.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a general transfer type electrophotographic apparatus. Reference numeral 1 denotes an electrophotographic photosensitive member, 2 denotes a corona charging device, 3 denotes an exposure unit, 4 denotes a developing unit, 5 denotes a transfer unit, 6 denotes a cleaning unit, 7 denotes a pre-exposure unit, 8 denotes an image fixing unit, and L denotes an optical image. Exposure, P, is a transfer material that has undergone image transfer. FIG. 2 is a block diagram of a facsimile using the electrophotographic apparatus as a printer. Reference numeral 9 denotes an image reading unit, 10 denotes a controller, 11 denotes a receiving circuit, 12 denotes a transmitting circuit, 13 denotes a telephone, 14 denotes a line, 15 denotes an image memory, 16 denotes a CPU, 17 denotes a printer controller, and 18 denotes a printer.

Claims (4)

(57) [Claims] 1. An electrophotographic photoreceptor comprising a photosensitive layer containing a disazo pigment represented by the following general formula (1) on a conductive support. General formula In the formula, Ar ₁ and Ar ₂ are the same or different, and each represents a carbocyclic aromatic group or a heterocyclic aromatic group which may have a substituent, and R ₁ and R ₂ represent a hydrogen atom, an alkyl group or a cyano aromatic group. A ₁ and A ₂ are the same or different and represent a coupler residue having a phenolic hydroxyl group. 2. The electrophotographic photosensitive member according to claim 1, wherein the photosensitive layer comprises at least two layers of a charge generation layer containing a disazo pigment represented by the general formula (1) and a charge transport layer. 3. An electrophotographic apparatus comprising the electrophotographic photosensitive member according to claim 1. 4. A facsimile comprising: an electrophotographic apparatus provided with the electrophotographic photosensitive member according to claim 1; and a receiving means for receiving image information from a remote terminal.