JPS636562A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To obtain the titled body having high sensitivity and stable potential characteristics by incorporating diazo pigment shown by a specific formula to the photosensitive layer of the titled body. CONSTITUTION:The titled body is mounted the photosensitive layer which is composed of an electric charge generating layer and an electric charge transfer layer, on a conductive substrate. To give sufficient absorbancy to the titled body, the electric charge generating layer comprises the photosensitive layer which contains the disazo pigment shown by the formula wherein R1, R2, and R3 are the same or different with each other and are each hydrogen or halogen atom, alkyl, alkoxy, cyano or nitro group, A is a coupler residue having a phenolic OH group. The generated electric charge carrier is effectively transferred to the interface between the electric charge generating layer and the electric charge transfer layer, or the interface between the electric charge generating layer and the conductive substrate plate. The photoconductive film of the electric charge generating layer is a thin film having for example, >=5mu, preferably, 0.01-1mu thickness. Thus, the titled body having high sensitivity and stable potential characteristics, is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to an electrophotographic photoreceptor, and more particularly to an electrophotographic photoreceptor having a photosensitive layer containing a specific azo pigment.

[Prior Art] Pigments and dyes exhibiting photoconductivity have been published in numerous publications.

For example, “RCA Review” Vol.
, 23.413-419 (1962, 9), there is a presentation on the photoconductivity of phthalocyanine pigments.
Further, electrophotographic photoreceptors using this phthalocyanine pigment are disclosed in US Pat. No. 3,397,086 and US Pat.
It is stated in Specification No. 8 etc. Other organic semiconductors used in electrophotographic photoreceptors include, for example, US Pat.
Specification No. 15983, Specification No. 4327169 and '
“Re5each Disclosure”2051
7 (1981, 5), methine squaric acid dyes described in U.S. Pat. No. 3,824,099, and U.S. Pat. No. 3,89808.
Examples include disazo pigments described in Specification No. 4, Specification No. 4251613, and the like. Such organic photoconductors are easier to synthesize than inorganic photoconductors, and their sensitivity to visible light wavelengths can be changed relatively easily through molecular design, making it easy to control photosensitivity. In recent years, various companies have been competing with each other to develop photoconductors, as they are non-polluting, highly productive and economical, and have reached the level of practical use in terms of sensitivity and durability. However, there is still a need to improve the level of the calendar.

However, in recent years, these organic photoconductors have been
There has been a rapid increase in demand for extending the photosensitive wavelength range to around 0 nm (which is the most preferred in terms of economy, output, matching with photosensitive materials, etc.) and for use as photoreceptors for digital recording such as laser printers.

Considering conventional organic photoconductors from this point of view.

The above-mentioned phthalocyanine pigment, an improved aluminum phthalocyanine pigment described in U.S. Pat. No. 4,426,434, and the triphenylamine trisazo pigment described in U.S. Pat. No. 4,436,800 and U.S. Pat. No. 4,439,506. , U.S. Patent No. 4447
Tetrakisazo pigments described in No. 51 have been proposed as photoconductors for semiconductor lasers.

However, when using an organic photoconductor as a photoconductor for semiconductor lasers, firstly, the photosensitive wavelength range must extend to long wavelengths, secondly, the sensitivity and durability must be good, and the semiconductor laser Since the wavelength of the light changes, it is necessary that the sensitivity be constant over a wide wavelength range and that productivity be good.

The above-mentioned organic photoconductor does not satisfy these conditions.

[Problems to be Solved by the Invention] A first object of the present invention is to provide a novel electrophotographic photoreceptor.

A second object is to provide an electrophotographic photoreceptor having practical sensitivity characteristics in the visible region and stable potential characteristics upon repeated use.

The third object is to provide a novel photoconductor for near-infrared rays.

The fourth purpose is to provide electrophotography with practical high sensitivity characteristics and stable potential characteristics during repeated use in processes that use semiconductor lasers for digital recording photoreceptors such as laser copying, laser beam printers, LED printers, and CRT printers. The purpose is to provide a photoreceptor.

[Means and effects for solving the problems] As a result of intensive research and development, the present inventors have found that by using the azo pigment of the present invention as a photoconductor, - the usefulness as a general electrophotographic photoreceptor. Needless to say, it has also been successfully used as a photoconductor for near-infrared rays to fully satisfy the above conditions.

That is, the present invention is based on the general formula (wherein R,, R2 and R3 are the same or different,
Hydrogen atoms, alkyl groups, alkoxy groups.

It is composed of an electrophotographic photoreceptor characterized in that the photosensitive layer contains a disazo pigment represented by (A represents a halogen atom, a cyano group, or a nitro group, and A represents a coupler residue having a phenolic OH group). .

Furthermore, A in the general formula (1) is particularly suitable for the following general formula (2).
) to (8).

-X' In the formula, X is 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 which may be fused with a benzene ring and have a substituent. In particular, the fused ring of X, which represents a residue forming a polycyclic aromatic ring or a heterocycle, has good electrophotographic properties when used as a naphthalene ring or a benzcarbazole ring.

Examples of substituents that X has include alkyl groups such as methyl, ethyl, and propyl, halogen atoms such as fluorine, chlorine, bromine, and iodine, flukoxy groups such as methoxy and ethoxy, nitro groups, cyano groups, and trifluoromethyl groups. .

R4 and R5 are a hydrogen atom, an alkyl group such as methyl, ethyl, propyl, butyl which may have a substituent, a heptaralkyl group such as benzyl, phenethyl, naphthylmethyl, an aryl group such as phenyl, diphenyl, naphthyl, anthryl, etc. , carbazole, cyhenzofuran, benzimidacylone, benzthiazole, thiazole, pyridine, etc., or a cyclic amino group together with the nitrogen atom to which R4 and R5 are bonded.

In particular, the electrophotographic properties are particularly good when R4 is a phenyl group having an electron-withdrawing group such as nitro, cyano, or trifluoromethyl, and R5 is a hydrogen atom.

General formula General formula R6 and R7 in the above general formulas (3) and (4) are
Indicates an alkyl group such as methyl, ethyl, propyl, butyl, etc. which may have a substituent, an aralkyl group such as benzyl, phenethyl, naphthylmethyl, etc., and a 7-aryl group such as phenyl, diphenyl, naphthyl, anthryl.

Examples of the optional substituents of the alkyl group, aralkyl group, aryl group, and heterocyclic group represented by R4-R7 in the above general formulas (2) to (4) include methyl, ethyl, propyl, butyl, etc. Substitution of alkyl groups, flukoxy groups such as methoxy, ethoxy, propoxy, halogen atoms such as fluorine atoms, chlorine atoms, bromine atoms, iodine atoms, nitro groups, cyano groups, dimethylamino, diethylamine, dibenzylamino, diphenylamino, etc. Examples include amine groups.

Y in the above general formulas (5) and (6) represents a divalent group of an aromatic hydrocarbon or a divalent group of a petero ring containing a nitrogen atom as a heteroatom, and Y represents a divalent group of an aromatic hydrocarbon. As for monocyclic aromatic hydrocarbons such as O-phenylene,
and divalent groups of condensed polycyclic aromatic hydrocarbons such as 0-naphthylene, perinaphthylene, 1,2-antrylene, and 9,10-phenanthrylene.

In addition, examples of the heterocyclic divalent group containing a nitrogen atom as a heteroatom include 3.4-pyrazolediyl, 2.3-pyridinediyl, 4,5-pyrimidinediyl, 4.7-indazolediyl, 5.6- benzimidazolediyl,
Examples include 6,7-chiralindiyl group.

R8 in the general formula (7) represents a 7-aryl group such as phenyl, naphthyl, anthryl, pyrenyl, etc., which may have a substituent, or a heterocyclic group such as pyridyl, thienyl, furyl, carbazolyl, etc., and further has a substituent. Examples of optional substituents include fluorine atom, chlorine atom, bromine atom, iodine atom, etc.
＼Rogen atoms, alkyl groups such as methyl, ethyl, propyl, butyl, flukoxy groups such as methoxy, ethoxy, propoxy, butoxy, nitro groups, cyano groups, dimethylamino, diethylamino, dipropylamino, dibenzylamino, diphenylamino, morpholino, piperidino,
Examples include substituted amino groups such as pyrrolidino.

R9 and RIQ in the general formula (8) are an alkyl group such as methyl, ethyl, propyl, butyl which may have a substituent, an aralkyl group such as benzyl, phenethyl, naphthylmethyl, phenyl, naphthyl, anthryl, diphenyl, etc. 7-aryl groups such as carbazole, dibenzofuran, benzimidacylon, benzthiazole, thiazole, pyridine, etc., and optional substituents include fluorine atom, chlorine atom, bromine atom, Halogen atoms such as iodine atoms, alkyl groups such as methyl, ethyl, propyl, butyl, and methoxy.

Flukoxy groups such as ethoxy, propoxy, butoxy, nitro groups, cyano groups, dimethylamino, diethylamino,
Examples include substituted amide groups such as dipropylamino, dibenzylamino, diphenylamino, morpholino, piperidino, and pyrrolidino.

The central skeleton of the disazo pigment used in the present invention has excellent planarity and moderate electron-attracting properties, making it compatible with the charge transport layer, resulting in high sensitivity and excellent potential stability during long-term use. It is estimated that a photographic photoreceptor can be obtained.

By achieving high sensitivity, it becomes possible to apply it to high-speed copying machines, laser beam printers, LED printers, liquid crystal printers, etc. Furthermore, since a stable potential is maintained regardless of the previous history of the photoconductor, it is possible to improve the image quality. Now you can get stable and beautiful images.

Representative examples of the disazo pigments used in the present invention are listed below.

Since only the portions A, R1, R2 and R3 are different, in the following pigment examples, only the portion A and the portions R, R2 and R3 are listed in the structure.

C)+1 One or two disazo pigments represented by the general formula (1)
More than one species can be used in combination.

The above-mentioned disazo pigment is produced by, for example, treating a diamine compound represented by the formula (wherein R,, R2, and R3 have the same meanings as above) with a nitrite salt to form a tetrazonium, and then converting the diamine compound represented by the general formulas (2) to (8) into a tetrazonium. ) is coupled in an aqueous system in the presence of an alkali, or the tetrazonium salt of the diamine compound is once isolated in the form of BF4 salt, PF, salt or zinc chloride double salt. After that, it can be easily produced by coupling with a coupler in a suitable solvent such as N,N-dimethylformamide or dimethyl sulfoxide in the presence of an alkali.

Next, as a typical synthesis example, the above-mentioned disazo pigment example (1)
We will explain how to synthesize.

In a 500ml beaker, water 120mA% concentrated hydrochloric acid 24.9
m (0.29 mol), diamine with the following structural formula 13.6
g (0,0435 mol) and stirred while cooling in an ice water bath to bring the liquid temperature to 3°C.

Next, a solution of 6.3 g (0,092 mol) of sodium nitrite dissolved in 10 mjL of water was added dropwise over 25 minutes while controlling the liquid temperature within the range of 0 to 5°C. Stir for a minute.

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

Next, put 11 parts of water in 21 beakers and add 3 parts of sodium hydroxide.
After dissolving 1.5 g, (0,788 mol) of naphthol As (3-hydroxy-2-naphthoic acid anilide) 2
4.2 g ((10919 mol)) was added and dissolved.

This coupler solution was cooled to 6°C, and while controlling the liquid temperature at 6 to 10°C, the above-mentioned tetrazotization solution was added dropwise with stirring over 30 minutes, then stirred for 2 hours, and further stirred for 1 hour.
The 0 reaction solution left overnight was filtered and washed with water to give a solid content of 35
．． 3g of water paste was obtained with 600mA of N, N-
Filtration with stirring was repeated four times at room temperature using dimethylformamide. Thereafter, stirring and filtration was repeated twice using 600 mjL of methyl ethyl ketone, followed by drying under reduced pressure to obtain 30.9 g of produced pigment (yield: 82.4%).

Melting point 〉300℃ Elemental analysis Calculated value (%) Experimental value (%) C73,34
75,30 H3,753,72 N 9.76 9.71 The synthesis method of typical disazo pigments has been explained above, but the general formula (
Other disazo pigments shown in 1) are synthesized in the same manner.

The aforementioned disazo pigment-containing material exhibits photoconductivity and can be used in the photosensitive layer of the electrophotographic photoreceptor described below.

That is, in a specific example of the present invention, the disazo pigment is applied to the photoconductive layer by forming a film on the conductive substrate by vacuum evaporation, or by forming a film by dispersing it in a suitable binder. An electrophotographic photoreceptor containing:

A preferred specific example is one in which 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 of the above-mentioned photoconductive disazo pigment as possible in order to obtain sufficient absorbance, and the generated charge carriers reach the interface with the charge transport layer or the conductive substrate. Transported efficiently.

For this purpose a thin film layer, for example less than 5 l, preferably 0.0
Preferably, the thin film layer has a thickness in the range of 1 to 1 tile.

This is because most of the incident light is absorbed by the charge generation layer.
This is due to the need to generate a large number of charge carriers and to inject the generated charge carriers into the charge transport layer without being deactivated by recombination or trapping.

The charge generation layer can be formed by dispersing a disazo pigment in a suitable binder and coating it on a conductive substrate, or by forming a deposited film using a vacuum deposition apparatus.

The binder used when forming the charge generation layer by coating can be selected from a wide range of insulating resins, and
It can be selected from organic conductive polymers such as N-vinylcarbazole, polyvinylanthracene, and polyvinylpyrene. Preferably polyvinyl butyral, polyarylate (condensation polymer of bisphenol A and heptalic acid, etc.), polycarbonate, polyester, phenoxy resin, polyvinyl acetate, acrylic resin, polyacrylamide, polyamide, polyvinylpyridine, cellulose resin, urethane resin, Examples include insulating resins such as epoxy resin, casein, polyvinyl alcohol, and polyvinylpyrrolidone.

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 varies depending on the type of resin, and the solvent used for the charge transport layer, undercoat, etc. It is preferable to select one that does not dissolve the calendar.

Specifically, alcohols such as methanol, ethanol, and isopropanol, ketones such as acetone, methyl ethyl ketone, and cyclohexanone, amides such as N,N-dimethylformamide, N,N-dimethylacetamide, and sulfoxides such as dimethyl sulfoxide. kind,
Ethers such as tetrahydrofuran, dioxane, ethylene glycol monomethyl ether, esters such as methyl acetate, ethyl acetate, aliphatic halogenated hydrocarbons such as chloroform, methylene chloride, dichloroethylene, carbon tetrachloride, trichloroethylene, or benzene, Aromatic hydrocarbons such as toluene, xylene, ligroin, monochlorobenzene, dichlorobenzene, etc. can be used.

Coating methods include dip coating, spray coating, spinner coating, bead coating,
This can be carried out using methods such as a Mayer bar coating method, a blade coach ink method, a roller coach ink method, and a curtain coating method. Drying is preferably carried out by drying to the touch at room temperature and then heating. Drying by heating can be carried out at a temperature of 30 to 200° C. for a period of from 5 minutes to 2 hours, either stationary or under ventilation.

The charge transport layer is electrically connected to the charge generation layer described above, and has the function of receiving and taking charge carriers injected from the charge generation layer in the presence of an electric field, and transporting these charge carriers to the surface. have. The charge transport layer may be laminated on or below the charge generation layer.

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

When the photosensitive wavelength range of the charge transport layer coincides with or overlaps that of the charge generation layer, charge carriers generated in both layers trap each other, resulting in a decrease in sensitivity.

Charge-transporting substances include electron-transporting substances and hole-transporting substances. Examples of electron-transporting substances include chloranil, bromoanil, tetracyanoethylene, tetracyanoquinodimethane, and 2,4.7-)nitro-9. -fluorenone,
2,3,5.7-tetranitro-9-fluorenone, 2
, 4.7-dolinitro-9-dicyanomethylenefluorenone, 2.4,5.7-tetranitroxanthone, 2゜4.8-)linitrothioxanthone and other electron-withdrawing substances, and polymerization of these electron-withdrawing substances Examples include things that have been done.

Examples of hole transporting substances include pyrene, N-ethylcarbazole, N-isopropylcarbazole, N-methyl-N
-Phenylhydrazino-3-methylidene-9-ethylcarbazole, N,N-diphenylhydrazino-3-methylidene-9-ditylcarbazole, N,N-diphenylhydrazino-3-methylidene-10-ethylphenothiazine, N , N-diphenylhydrazino-3-methylidene-10-ditylphenoxazine, 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-diethylbenzaldehyde-3
-Hydrazones such as methylbenzthiazolinone-2-hydrazone, 2,5-bis(P-diethylaminophenyl)-1,3,4-oxadiazole, 1-phenyl-3
-(p-diethylaminostyryl)-5-(p-diethylaminophenyl)pyrazoline, l-[quinolyl (2)
] -3-(,p-diethylaminostyryl)-5-(
p-diethylaminophenyl)pyrazoline, l-[pyridyl(2)]-3-(p-diethyl7minostyryl)-
5-(p-diethylaminophenyl)pyrazoline.

1-[6-medoxypyridyl (2)] -3-(P-
diethylaminostyryl)-5-(p-diethylaminophenyl)pyrazoline, l-[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, l-phenyl-3-(p-diethylaminostyryl)-4-methyl-5-(p-diethylaminophenyl)pyrazoline, 1-phenyl-3-(
α-benzyl-p-diethylaminostyryl)-5-(
Pyrazolines such as p-diethylaminophenyl) pyrazoline and spiropyrazoline, 2-(p-diethylaminostyryl)-6-dinithylaminobenzoxazole, 2
-Oxazole compounds such as -(p-diethylaminostyryl)-4-(p-dimethylaminophenyl)-5-(2-chlorophenyl)oxazole, 2-(p-diethyl7minostyryl)-6-dinithylaminobenzothiazole, etc. thiazole compounds, triarylmethane compounds such as bis(4-diethylamino-2-methylphenyl)-phenylmethane, 1,1-bis(4-N,N-
diethylamino-2-methylphenyl)hebutane, 1,
Polyarylalkanes such as 1,2.2-tetrakis(4-N,N-dimethylamino-2-methylphenyl)ethane, triphenylamine, poly-N-vinylcarbazole, polyvinylpyrene, polyvinylanthracene, polyvinylacridine, Examples include poly-9-vinylphenylanthracene, pyrene-formaldehyde resin, and ethylcarbazole formaldehyde resin.

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

When the charge transport material does not have film-forming properties, a film can be formed by selecting an appropriate binder.

Resins that can be used as binders include, for example, acrylic resins, polyarylates, polyesters, polycarbonates, polystyrene, acrylonitrile-styrene copolymers, acrylonitrile-butadiene copolymers, polyvinyl butyral, polyvinyl formal, polsulfones, polyacrylamides, polyamides, chlorinated rubbers, etc. Insulating resin or poly-N-vinylcarbazole,
Mention may be made of organic photoconductive polymers such as polyvinylanthracene and polyvinylpyrene.

The charge transport layer cannot be made thicker than necessary because there is a limit to how much charge carriers can be transported. Generally, the thickness is in the range of 5 to 30 IL, but the preferred range is 8 IL.
~20p.

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

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

As the substrate having the conductive layer, materials that are conductive themselves such as aluminum, aluminum alloy, copper, zinc, stainless steel, vanadium, molybdenum, chromium, titanium, nickel, indium, gold, platinum, etc. can be used. In addition, plastics (e.g., polyethylene, polypropylene, vinyl chloride resin, polyethylene terephthalate, acrylic resin, Polyfluorinated ethylene, etc.), conductive particles (e.g. carbon black, silver particles, etc.) coated on plastic with a suitable binder, conductive particles impregnated into plastic or paper, plastic with conductive polymer, etc. Can be used.

An undercoat layer having barrier and adhesive functions can also be provided between the conductive layer and the photosensitive layer.

The undercoat layer can be formed from casein, polyvinyl alcohol, nitrocellulose, ethylene-acrylic acid copolymer, polyamide (nylon 6, nylon 66, nylon 61O1 copolymerized nylon, alkoxymethylated nylon, etc.), polyurethane, gelatin, aluminum oxide, etc. .

The thickness of the undercoat layer is 0.1 to 5 μl, preferably 0.5 to 5 μl.
A range of 3p is appropriate.

mMt in the order of conductive layer, charge generation layer, and charge transport layer.

When using a photoconductor, when the charge transport material is an electron transport material, it is necessary to charge the surface of the charge transport layer positively, and when exposed to light after charging, electrons generated in the charge generation layer are released in the exposed area. It is injected into the charge transport layer and then reaches the surface to neutralize the positive charge, resulting in an attenuation of the surface potential and an electrostatic contrast with the unexposed areas.

A visible image is obtained by developing the electrostatic latent image thus formed with a negatively charged toner. Fix this directly or
Alternatively, the toner image can be transferred to paper or plastic film, 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 also be used. The type of developer, developing method, and fixing method may be any known developer or known method, and are not limited to a specific one.

On the other hand, when the charge transport material is a hole transport material, the surface of the charge transport layer must be negatively charged, and when exposed to light after charging, holes generated in the charge generation layer are injected into the charge transport layer in the exposed area. After that, it reaches one surface and neutralizes the negative charges, resulting in an attenuation of the surface potential and an electrostatic contrast between it and the unexposed area.

During development, it is necessary to use a positively charged toner, contrary to the case where an electron transporting substance is used.

When using a photoreceptor in which a conductive layer, a charge transport layer, and a charge generation layer are laminated in this order, if the charge transport substance is an electron transport substance, the surface of the charge generation layer must be negatively charged, and after charging, When exposed to light, electrons generated in the charge generation layer are injected into the charge transport layer in the exposed portion, and then reach the substrate.

On the other hand, the holes generated in the charge generation layer reach the surface and the surface potential attenuates, creating an electrostatic contrast with the unexposed area.

A visible image is obtained by developing the electrostatic latent image thus formed with a positively charged toner. Fix this directly or
Alternatively, the toner image can be transferred to paper or plastic film, 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 also be used. The type of developer, developing method, and fixing method may be any known developer or known method, and are not limited to a specific one.

On the other hand, when the charge generation layer is made of a hole transporting substance, it is necessary to positively charge the surface of the charge generation layer, and when exposed to light after charging, the holes generated in the charge generation layer become charged in the exposed area. It is injected into the transport layer and then reaches the substrate.

On the other hand, the electrons generated in the charge generation layer reach the surface and the surface potential is attenuated, creating an electrostatic contrast with the unexposed area. During development, it is necessary to use a negatively charged toner, contrary to the case where an electron transporting substance is used.

Further, as the electrophotographic photoreceptor of the present invention, an electrophotographic photoreceptor containing the above-mentioned specific disazo pigment and a charge transport material in the same layer can be mentioned.

In any type of electrophotographic photoreceptor, the pigment used contains at least one type of pigment selected from disazo pigments represented by the general formula (1), and the crystal form thereof may be amorphous or crystalline. Either is fine.

In some cases, two or more types of disazo pigments represented by the general formula (1) may be combined for the purpose of increasing the sensitivity of the photoreceptor by using a combination of pigments with different light absorption, or 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 used not only in electrophotographic copying machines, but also in digital electrophotographic copying machines, laser beam printers, CRT printers, LED printers, liquid crystal printers, laser plate making, etc. The recording system can also be widely used in many electrophotographic applications.

[Example] Examples 1 to 15 Ammonia aqueous solution of casein (casein 1
1.2 g of 28% ammonia water, 1 g of 28% ammonia water, and 222 m of water) was applied and dried using a Meyer bar so that the film thickness after drying was 1.0 mm.

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

Then, P-diethylaminobenzaldehyde-N-α
- Dissolve 5 g of naphthyl-N-phenylhydrazone and 5 g of polymethyl methacrylate (number average molecular weight 100,000) in 70 m of benzene, and apply this onto the charge generation layer so that the film thickness after drying is 15 mm. The electrophotographic photoreceptor of Example 1 was prepared by coating with a bar and drying to form a charge transport layer.

Electrophotographic photoreceptors corresponding to Examples 2 to 15 were created in the same manner as Example 1, using the pigment of the disazo pigment example described in the experimental results column below in place of the pigment example (1). .

The electrophotographic photoreceptor prepared above was tested using an electrostatic copying paper tester (
Using Mode sentence 5P-428 (manufactured by Kawaguchi Electric),
Static method, corona charging at -5KV, 1 in the dark
After being held for a second, it was exposed to light at an illuminance of 2 lux, and the charging characteristics were examined.

The charging characteristics include the surface potential (vO) and the exposure amount (El/
2) was measured.

1 (1) 600
3.82 (2) 590
1.83 (4) 57
0 4.04 (5)
810 3.55 (6)
620 3.06 (
8) 600 2.38
(16) 610 4.19
(19) 600 2.010
(20) 580 4.5
11 (21) 590
3.912 (23) 590
2.213 (24) 60
0 2.514 (29)
620 3.215 (37)
610 3.5 From the above results, it can be seen that all the electrophotographic photoreceptors of the present invention have sufficient charging ability and sufficient sensitivity.

Examples 16 to 21 5 g of the disazo pigment example (9) was added to 95 mJl of methyl isobutyl ketone with benzal resin (synthesized from benzal and poval with a degree of polymerization of 500, degree of benzalization 70 mol%)
) was added to the solution in which 2 g was dissolved, and the mixture was dispersed using a sand mill for 4 hours. After drying this dispersion on an aluminum plate, the film thickness was 0.51.
It was coated with a Mayer bar to form a charge generating layer L and dried.

Next, 5 g of 1-p-diethylaminophenyl-2-α-naphthylethylene and 5 g of polymethyl methacrylate (number average molecular weight 100,000) were dissolved in 70 ml of benzene, and this was placed on the charge generation layer so that the film thickness after drying was 1.5 g. Coat with a Meyer bar to form a charge transport layer and dry.
An electrophotographic photoreceptor of Example 16 was prepared.

In place of the above pigment example (9), pigment examples (11) and (12)
, (13), (14), and (17), the above Example 1
Electrophotographic photoreceptors corresponding to Examples 17 to 21 were prepared in the same manner as in Example 6.

An electrostatic copying paper testing device (ModefL
Using a modified machine of 5P-428 (manufactured by Kawaguchi Electric Co., Ltd.),
The sample was statically charged with corona at 15 KV, held in a dark place for 1 second, and then exposed to laser light to measure the charging characteristics.

The charging characteristics include the surface potential (Vo) and the amount of light exposure (E) required to attenuate the potential to 115 after dark decaying for 1 second.
115) was measured.

Example V o ('V) E 115 (u
-J/am'') 16 600 2.5 17 620 3.0 18 600 2.8 19 610 2.1 20 620 2.3 21 590 4.0 From the above results, the electrophotographic photoreceptor of the present invention.

It is clear that both have sufficient sensitivity and potential characteristics.

Example 1.2. Using the electrophotographic photoreceptors prepared in s, 11.16 and 18, variations in bright area potential and dark area potential during repeated use were measured.

The measurement was carried out by attaching the photoreceptor to the cylinder of an electrophotographic copying machine equipped with a -5 KV corona charger, an exposure optical system, a developer, a transfer charger, a static elimination exposure optical system, and a cleaner. This copying machine is configured to produce an image on transfer paper as a cylinder is driven.

The initial bright area potential (VL) and dark area potential (Vo) were set to around -toov and -600V, respectively, and the bright area potential (VL) and dark area potential (Vo) after 5,000 uses were measured.

16 600 140 580 1
7°0 Example 22 On the charge generation layer formed in Example 6, 2, 4, 7-
) IJ nitro-9-fluorenone 5g and poly-4,4
'-Dioxydiphenyl-2,2-propane carbonate (number average molecular weight 300,000) 5g was added to 7g of tetrahydrofuran.
A coating solution prepared by dissolving in 0 mJl was applied and dried so that the coating amount after drying was 10 g/m2. The charging characteristics of the electrophotographic photoreceptor thus prepared were measured in the same manner as in Example 1. The charging polarity was set to 10.

v, ): +590V El/2: 3.2 lux, sec Example 23 Ammonia aqueous solution of casein (casein 11.2g, 28% ammonia water Ig, water 222g) was placed on an aluminum cylinder.
mfL) was applied and dried using a Mayer bar so that the film thickness after drying was 1.0 turns.

Next, 1 part by weight of the pigment of Disazo Pigment Example (9), 1 part by weight of butyral resin (trade name: Kosuretsu BM-2, manufactured by Tsukushiki Kagaku ■) and 30 parts by weight of isopropyl alcohol were dispersed in a ball mill dispersion machine for 4 hours. This dispersion was applied onto the previously formed casein layer by a dip coating method so that the film thickness after drying would be 0.3 mm, and dried to form a charge generation layer.

Next, 1 part by weight of 4-diphenylamino-4'-methoxystilbene, 1 part by weight of polysulfone (trade name P1700, manufactured by Union Carbide), and 6 parts by weight of monochlorobenzene.
Parts by weight were mixed, stirred, and dissolved. This solution was applied onto the charge generation layer using a dip coating method and dried until the film thickness was 1.
2. A charge transport layer was formed.

Corona discharge of 15 KV was applied to the produced electrophotographic photoreceptor. The surface potential at this time was measured (initial potential V o
) *Furthermore, the surface potential of this photoreceptor was measured after it was left in a dark place for 5 seconds (dark decay V7C).

Evaluation was made by measuring the exposure amount (El/2J/Cm2) required for decay.

At this time, the light source was a gallium/aluminum/propylene ternary semiconductor laser (output 5 mW, oscillation wavelength 780 nm).
) was used. Show the results.

Vony 580V, El/2: 0, 8 g J/cm
2. Next, the photoreceptor was placed on the photoreceptor of the printer in a laser beam printer (product name: LBP-CX, manufactured by Kya/7■), which is an electrophotographic printer using a reverse development method and equipped with the same semiconductor laser as above. The zero conditions that were set instead and the actual image test was conducted were as follows.

Surface potential knee after primary charging: 700 V, surface potential knee after image exposure: 150 V (exposure amount: 1.2 gJ/cm2), transfer potential: +700 V, developer polarity: negative polarity, process speed: 50 mm/sec.

Development conditions (development bias) knee 450V, image exposure scan method: image scan, - exposure before next charging: 501u
x, full red exposure of sea.

Image formation was performed by line scanning a laser beam in accordance with character signals and image signals.

Good prints were obtained for both text and images.

Example 24 A film thickness of 0.5! is applied on the aluminum surface of an aluminum-deposited polyethylene terephthalate film. A film of polyvinyl alcohol was formed.

Next, the disazo pigment dispersion used in Example 1 was applied onto the polyvinyl alcohol layer using a Mayer bar so that the film thickness after drying was 0.5#L, and dried to form a charge generation layer. did.

Next, 5 g of l-[pyridyl(2)]-3-(p-diethylaminostyryl)-s-(p-diethylaminophenyl)pyrazoline and 5 g of polyarylate (condensation polymer of bisphenol A and terephthalic acid-isophthalic acid) were added. A solution prepared by dissolving 100 μl of chloride in 70 mL of tetrahydrofuran was applied onto the charge generation layer so that the film thickness after drying would be 10 JL, and dried to form a charge transport layer.

The charging characteristics and durability characteristics of the produced electrophotographic photoreceptor were measured in the same manner as in Example 1.

Charging characteristics VO knee 600V El/2: 3.5 sentence ux, 5ec As is clear from the above results, the sensitivity is also good.

The potential stability during long-term use was also good.

Example 25 On the casein layer of the aluminum plate on which the casein layer used in Example 1 was formed, a charge transport layer of fii composition similar to Example 1,
An electrophotographic photoreceptor was prepared in exactly the same manner as in Example 1, except that the charge generation layers were sequentially laminated and the structure of each layer was different, and the charging characteristics were measured in the same manner as in Example 1. However, the charging polarity was set to 10.

Vo: +590V El/2: 3.3 lux, see Furthermore, durability characteristics were measured in the same manner as in Example 1 except that the charge was set to 10.

[Effects of the Invention] The electrophotographic photoreceptor of the present invention contains a specific disazo pigment in the photosensitive layer, thereby improving carrier generation efficiency and/or carrier transport efficiency within the photosensitive layer containing the pigment. It is an electrophotographic photoreceptor with improved sensitivity, high sensitivity, and excellent potential stability during long-term use.Furthermore, it is an excellent electrophotographic photoreceptor with sensitivity even in a long wavelength range.

Claims (10)

[Claims] (1) General formula ▲ Numerical formula, chemical formula, table, etc. ▼ (1) (In the formula, R_1, R_2, and R_3 are the same or different, hydrogen atom, alkyl group, alkoxy group, halogen atom, cyano group, or nitro group) 1. An electrophotographic photoreceptor characterized in that a photosensitive layer contains a disazo pigment represented by the following formula (A represents a coupler residue having a phenolic OH group). (2) In the general formula (1), A is the general formula ▲ Numerical formula, chemical formula, table, etc. ▼ (2) (In the formula, X is a naphthalene ring which is fused with a benzene ring and may have a substituent, Represents a residue forming a polycyclic aromatic ring or heterocycle selected from anthracene ring, carbazole ring, benzcarbazole ring, dibenzofuran ring, benzonaphthofuran ring, and diphenylene sulfide ring, and R
_4 and R_5 represent a hydrogen atom, an alkyl group that may have a substituent, an aralkyl group, an aryl group, a heterocycle, or a cyclic amino group together with the nitrogen atom to which R_4 and R_5 are bonded. 2. The electrophotographic photoreceptor according to item 1. (3) In the general formula (1), A is the general formula ▲ Numerical formula, chemical formula, table, etc. ▼ (3) (In the formula, R_6 is an alkyl group, an aralkyl group, or an aryl group that may have a substituent. The electrophotographic photoreceptor according to claim 1, which is represented by ). (4) In general formula (1), A is a general formula ▲ Numerical formula, chemical formula, table, etc. ▼ (4) (In the formula, R_7 is an alkyl group, aralkyl group, or aryl group that may have a substituent. The electrophotographic photoreceptor according to claim 1, which is represented by ). (5) In the general formula (1), A is the general formula ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (5) (In the formula, Y includes a divalent group of aromatic hydrocarbon or a nitrogen atom as a hetero atom. Indicates a divalent group of a heterocyclic ring,
) The electrophotographic photoreceptor according to claim 1. (6) In the general formula (1), A is the general formula ▲ Numerical formula, chemical formula, table, etc. ▼ (6) (In the formula, Y contains a divalent aromatic hydrocarbon group or a nitrogen atom as a heteroatom. Indicates a divalent group of a heterocyclic ring,
) The electrophotographic photoreceptor according to claim 1. (7) In the general formula (1), A is the general formula ▲ Numerical formula, chemical formula, table, etc. ▼ (7) (In the formula, R_8 is an aryl group or a hetero ring that may have a substituent, and X is benzene. A polycyclic aromatic ring or hetero 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, which may be fused with a ring and have a substituent. 2. The electrophotographic photoreceptor according to claim 1, which is represented by ), which indicates a residue to be formed. (8) In the general formula (1), A is the general formula ▲ Numerical formula, chemical formula, table, etc. ▼ (8) (In the formula, R_9 and R_1_0 are an alkyl group, an aralkyl group, an aryl group that may have a substituent. group or heterocycle, X is a polycyclic group 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 which may be fused with a benzene ring and have a substituent. The electrophotographic photoreceptor according to claim 1, which is represented by ), which represents a residue forming an aromatic ring or a heterocycle. (9) Claims 1, 2, 3, and 4 consist of at least three layers: a conductive layer, a charge generation layer containing a disazo pigment represented by general formula (1), and a charge transport layer. section,
The electrophotographic photoreceptor according to item 5, 6, 7, or 8. (10) In the charge generation layer, A in general formula (1) is a general formula ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (2') (In the formula, R_1_1 is a halogen atom, a nitro group, a cyano group, or a trifluoromethyl X represents a group selected from the group consisting of a naphthalene ring, an anthracene ring, a carbazole ring, a benzcarbazole ring, a dibenzofuran ring, a benzonaphthofuran ring, and a diphenylene sulfide ring, which may be fused with a benzene ring and have a substituent. 10. The electrophotographic photoreceptor according to claim 9, which contains a disazo pigment represented by ), which represents a selected residue forming a polycyclic aromatic ring or a heterocycle.