JPH0229658A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To improve sensitivity and the potential stability at the time of repetitive use by providing a photosensitive layer contg. a specific azo pigment on a conductive base. CONSTITUTION:The azo pigment of the electrophotographic sensitive body having the photosensitive layer contg. the azo pigment on the conductive base is the compd. expressed by the formula I. In the formula I, Ar denotes a substd. or unsubstd. arom. hydrocarbon group or heterocyclic group which may be bonded via a bond group, Cp denotes a residual coupler group having a phenolic hydroxyl group; at least one of Cp is the residual coupler group expressed by the formula II, and n denotes 1-4 integers. In the formula II, Z denotes a residual group necessary for forming a polycyclic arom. ring or heterocycle which may have a substituent by condensing with a benzene ring; R1 denotes an alkyl group, aralkyl group, etc., which may have a substituent. Either or both of carrier generation efficiency or implantation efficiency in the photosensitive body are improved by using such azo pigment for the photosensitive layer, by which the photosensitive body having the excellent sensitivity and potential stability at the time of repetitive use is obtd.

Description

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

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

On the other hand, electrophotographic photoreceptors made of organic photoconductive substances include photoconductive polymers typified by poly-N-vinylcarbazole and 2.5-bis(p-diethylaminophenyl)-1,:1.4. -Those using low-molecular organic photoconductive substances such as oxadiazole, and those in which such organic photoconductive substances are combined with various dyes and pigments are known.

Electrophotographic photoreceptors using organic photoconductive substances have good film forming properties and can be produced by coating, making them extremely productive.
It has the advantage of being able to provide an inexpensive photoreceptor. Furthermore, it has the advantage that color sensitivity can be freely controlled by selecting the sensitizers used, such as dyes and pigments, and a wide range of studies have been carried out to date. Particularly recently, with the development of a functionally separated photoreceptor in which an organic photoconductive pigment is used as a charge generation layer and a charge transport layer made of the aforementioned photoconductive polymer or a low-molecular organic photoconductive substance is laminated, Significant improvements have been made in the sensitivity and durability, which were considered to be shortcomings of conventional organic electrophotographic photoreceptors.

Many pigments have been proposed for use in organic electrophotographic photoreceptors, but azo pigments in particular have been widely studied because pigments with various properties can be synthesized depending on the combination of amine components and coupler components. There is.

The coupler components used in such azo pigments include:
Naphthol couplers described in JP-A-47-37543, etc., benzcarbazole-based couplers described in JP-A-58-122967, etc., JP-A-54-
Naphthalimide couplers described in JP-A No. 79632, perinone couplers described in JP-A-57-176055, and the like are already known.

[Problems to be Solved by the Invention] However, when the above azo pigment is used, there are problems in terms of sensitivity and potential stability during repeated use.

Only extremely fine materials have been put into practical use.

It is therefore an object of the present invention to provide novel photoconductive materials. Another object of the present invention is to provide an electrophotographic photoreceptor having practical high sensitivity characteristics and stable potential characteristics during repeated use.

[Means for Solving the Problem] The problem is to provide an electrophotographic photoreceptor having a photosensitive layer containing an azo pigment on a conductive support, wherein the azo pigment has the general formula: A1→N=N-CP). n (1) (in the formula,
A1 represents a substituted or unsubstituted aromatic hydrocarbon group or heterocyclic group which may be bonded via a bonding group, CP
represents a coupler residue having a phenolic hydroxyl group,
At least one of the CPs is a coupler residue represented by the following formula (2). n represents an integer from 1 to 4. ) The problem is solved by an electrophotographic photoreceptor characterized by being a compound represented by:

(In the formula, X represents a residue necessary to form a polycyclic aromatic ring or a heterocycle which may have a substituent by condensation with a benzene ring, and Ro may have a substituent. , alkyl group,
Specific examples of A1 in general formula (1), which represents an aralkyl group, an aryl group, or a heterocyclic group, include benzene, naphthalene, fluorene, phenanthrene, anthracene,
Hydrocarbon aromatic rings such as pyrene, furan, thiophene,
Heterocycles such as pyridine, indole, benzothiazole, carbazole, acridone, dibenzothiophene, benzoxazole, benzotriazole, oxadiazole, thiazole, etc., as well as the above aromatic rings and heterocycles directly or aromatic or non-aromatic groups. Combined with,
For example, triphenylamine, diphenylamine, N-methyldiphenylamine, biphenyl, terphenyl, binaphthyl, fluorenone, phenanthrenequinone, anthraquinone, benzanthrone, diphenyloxadiazole, phenylbenzoxazole, diphenylmethane, diphenylsulfone, diphenyl ether, pentuphenone, Stilbene, distyrylbenzene, tetraphenyl-p-phenylenediamine, tetraphenylbenzidine, N-phenyl-2-pyridylamine, N-phenyl-N-methyl-2-pyridylamine, N,N-diphenyl-2-pyridylamine , azafluorenone, etc.

The aromatic hydrocarbon group Σ and the heterocyclic group that may be bonded via the bonding group may have alkyl groups such as methyl, ethyl, propyl, and butyl; alkoxy groups such as methoxy and ethoxy; Examples include dialkylamino groups such as dimethylamino and diethylamino, halogen atoms such as fluorine, chlorine, and bromine, hydroxyl groups, nitro groups, cyano groups, and heromethyl groups.

X in general formula (2) is fused with a benzene ring to form a polycyclic aromatic ring or heterocycle such as a naphthalene ring, anthracene ring, carbazole ring, benzcarbazole ring, or dibenzofuran ring, which may have a substituent. Represents the residues necessary for Examples of substituents include alkyl groups such as methyl, ethyl, and propylo, alkoxy groups such as methoxy and ethoxy, halogen atoms such as fluorine, chlorine, and bromine, helomethyl groups such as trifluoromethyl, nitro groups, and cyano groups. .

Further, Ro is an alkyl group which may have a substituent.

Represents an aralkyl group, an aryl group, or a heterocyclic group, specifically an alkyl group such as methyl, ethyl, propyl, an aralkyl group such as benzyl, phenethyl, an aryl group such as phenyl, naphthyl, anthryl, pyridyl, thiazolyl, carbazolyl, etc. Examples include heterocyclic groups. Examples of these substituents include the same groups as the substituents for X in general formula (2).

In addition, in Cp of general formula (1), examples of coupler residues that may coexist in addition to the coupler residues shown in general formula (2) are shown in the following general formulas (4) to (8). Examples of such compounds include:

ゝX′ enemy -Y.

+X' - x in formulas (4), (5), and (6) has the same meaning as X in general formula (2).

Y in general formula (8) represents a divalent aromatic hydrocarbon or a divalent heterocyclic group containing a nitrogen atom in the ring. Specifically, 0-phenylene, 0-naphthylene, berinaphthylene, 1,2-antrylene, 3,4-pyrazolediyl, 2,3-pyridinediyl, 4.5-pyridinediyl,
Divalent groups such as 6,7-indazolediyl and 6,7-chiralindiyl can be mentioned.

-Z in formula (4) represents an oxygen atom or a sulfur atom, and the symbol represents O or l.

- Rt and Rs in formulas (4) and (5) represent a hydrogen atom, an alkyl group that may have a substituent, an aryl group, an aralkyl group, or a heterocyclic group; It may be combined with a nitrogen atom to form a cyclic amino group containing a nitrogen atom in the ring.

R4 in general formula (6) represents a hydrogen atom, an alkyl group, an aralkyl group, an aryl group, or a heterocyclic group which may have a substituent, and R5 in general formula (7) represents a hydrogen atom, an alkyl group that may have a substituent, represents an alkyl group, an aralkyl group, an aryl group, or a heterocyclic group.

Examples of the alkyl group in the above expression include methyl, ethyl, propyl, butyl, etc., aralkyl groups include benzyl, phenethyl, naphthylmethyl, etc., and aryl groups include phenyl, diphenyl, naphthyl, anthryl, etc. Examples of the heterocyclic group include pyridyl, thienyl, furyl, thiazolyl, carbazolyl, dibenzofuryl, benzimidazolyl, and benzthiazolyl, and examples of the cyclic amino group containing a nitrogen atom in the ring include virol and pyrroline. , pyrrolidine, pyrrolidone, indole, indoline, isoindole, carbazole, benzindole, imidazole,
Examples include cyclic amino groups derived from pyrazole, pyrazoline, oxazine, phenoxazine, benzocarbazole, and the like.

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

In addition, the pigment using a coupler in which X in formulas (2), (4), (5), and (6) is condensed with a benzene ring to form a benzcarbazole ring is Since it spreads to the vicinity of the region, it is suitable as a charge generating material for semiconductor lasers.

Typical examples of azo pigments used in the present invention are listed below.
The azo pigment used in the present invention is not limited to these.

The azo pigment of the Japanese invention can be produced by diazotizing the corresponding amine by a conventional method and coupling it with the coupler represented by the general formula (2) in the presence of an alkali in an aqueous system, or by adding a diazonium salt to a borofluoride salt or a zinc chloride complex. After converting to salt etc., N,
It can be easily synthesized by coupling with a coupler in an organic solvent such as N-dimethylformamide or dimethyl sulfoxide in the presence of a base such as sodium acetate, triethylamine, or triethanolamine.

In addition, when synthesizing a disazo pigment in which a coupler other than the coupler represented by general formula (2) coexists in the molecule, the corresponding diamine is tetrazotized by a conventional method and isolated as the above-mentioned solubilizing salt, and then Either 1 mol of the coupler represented by the general formula (2) is subjected to I coupling, and then 1 sol of a different type of coupler is coupled to synthesize the diamine, or one amino group of the diamine is protected with an acetyl group, etc., and this is diazotized. After coupling the coupler represented by the general formula (2), the protective group is hydrolyzed with hydrochloric acid or the like, this is diazotized again, and it can be synthesized by coupling with a different type of coupler.

Trisazo pigments and tetrakisazo pigments in which a coupler other than the coupler represented by general formula (2) coexists in the molecule are also synthesized in the same manner.

The coupler represented by the general formula (2) can be prepared, for example, by reacting allophanic acid ethyl ester with R1-Nl2 (RI has the same meaning as R□ in the general formula (2)) to form R,-HNoCI(N
After forming COOCJs, it is treated with concentrated ammonia water at around 100°C to form R+-HN0CHNOCNH2, which is then synthesized.

Next, examples of synthesis of the azo pigment of the present invention will be given.

Synthesis example (synthesis of the above-mentioned exemplified azo pigment No. (2)-8)
150ml of water in a 300ml beaker, 2011 concentrated hydrochloric acid
(0,032*ol) and cooled to 0℃, and in this, add a solution of 4.6 g (0,067*ol) of sodium dioxide dissolved in 10+*l of water to the liquid temperature of 5℃ or below. It was dropped into the liquid over a period of 10 minutes while maintaining the temperature. After stirring for 15 minutes, the mixture was filtered with carbon to obtain a solution of tetrazo salt. Add 10.5g (0,096*ol) of sodium borofluoride to this solution and 90ml of water.
1 was added dropwise, and the precipitated borofluoride salt was collected by filtration, washed with cold water, washed with acetonitrile, and dried under reduced pressure at room temperature.

Yield: 12.2g Yield: 84.6% Next, put 500ml of DMF in an ifL beaker and adjust the liquid temperature to 5°.
After cooling to C, 9.0 g of the previously obtained borofluoride salt (
0,020m01) and then triethylamine 5
．． 1 g (0,050+*ol) was added dropwise over 5 minutes. After stirring for 2 hours, the precipitated pigment was collected by filtration, washed 4 times with water and 3 times with water, and then freeze-dried.

Yield: 17.7g Yield: 85.0% Elemental analysis calculated value (z) Actual value (X) C59,9460,01 H3,303,25 N 15.14 15.23 The coating containing the azo pigment described above is photosensitive. It exhibits electrical conductivity and therefore can be used in the photosensitive layer of an electrophotographic photoreceptor.

That is, in a specific example of the present invention, an electrophotographic photoreceptor can be prepared by forming a film on a conductive substrate by dispersing the azo pigment in a suitable binder.

In a preferred embodiment of the present invention, a photoconductive coating containing the above-mentioned specific azo pigment is used 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. can be applied.

The charge generating layer contains the aforementioned specific azo pigments which exhibit as much photoconductivity as possible in order to obtain sufficient absorbance;
In addition, in order to efficiently transport the generated charge carriers to the interface between the charge transport layer and the conductive substrate, a thin film layer, for example, 51 Lm or less, preferably 0.01 to 17 Lm, is used.
A thin film layer having a thickness of zm is desirable.

This means that most of the incident light is absorbed by the charge generation layer, generating many charge carriers, and that the generated charge carriers are not deactivated by recombination or trapping, but are transferred to the charge transport layer. This is due to the need for injection.

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

Preferably polyvinyl alcohol, polyvinylbenzal, polyarylate (condensation polymer of bisphenol A and phthalic acid, etc.), polycarbonate, polyester, phenoxy resin, polyvinyl acetate, acrylic resin, polyacrylamide, polyamide, polyvinylpyridine, cellulose type. Examples include insulating resins such as resin, urethane resin, casein, polyvinyl alcohol, and polyvinylpyrrolidone. The resin content 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 is preferably selected from those that do not dissolve the underlying charge transport layer or undercoat layer.

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, esters such as tetrahydrofuran, dioxane, and ethylene glycol monomethyl ether, ethers such as methyl acetate and ethyl acetate, and aliphatic halogens such as chloroform, methylene chloride, dichloroethylene, carbon tetrachloride, and trichloroethylene. Hydrocarbons or aromatics such as benzene, toluene, xylene, monochlorobenzene, dichlorobenzene, etc. can be used.

Coating is done by dip coating method, spray coating method,
spinner coating method, beat coating method, Mayer-per coating method, blade coating method,
This can be carried out using a coating method such as a roller coating method or a curtain coating method.

For drying, it is preferable to dry to the touch at room temperature and then heat dry.Heat drying is performed at a temperature of 30 to 200°C for 5 minutes to 2 minutes.
It can be carried out stationary or under ventilation for a range of hours.

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.

In this case, 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, it is 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 with that of the charge generation layer, charge carriers generated in both layers capture each other, resulting in a decrease in sensitivity.

Charge transporting substances include electron transporting substances and hole transporting substances, and electron transporting substances include chloranyl, tetracyanoethylene, tetracyanoquinodimethane, 2,4
, 5.7-tetranitro-9-fluorenone, 2,4,
Examples include electron-withdrawing substances such as 5,7-tetranitroxanthone and 2,4,8-trinidrothioxanthone, and polymerized versions of these electron-withdrawing substances.

Examples of hole-transporting substances include pyrene, N-ethylcarbazole, N-methyl-phenylhydrazino-3-methylidene-9-ethylcarbazole, N,N-diphenylhydrazino-3-methylidene-10-ethylphenothiazine, p- Diethylaminobenzaldehyde-N,N-diphenylhydrazone, p-pyrrolidinobenzaldehyde-
Hydrazone compounds such as N,N-diphenylhydrazino, p-diethylhenzaldehyde 3-methylbenzthiazolinone-2-hydrazone, 2,5-bis(p-diethylaminophenyl)-1,3,4-oxadi Azole, l-phenyl-3-(p-diethylaminostyryl)-5-(p-diethylaminophenyl)pyrazoline,
1-[pyridyl(2)]-3-(p-diethylaminostyryl)-5-(p-diethylaminophenyl)pyrazoline, 1-[pyridyl(3)]-3-(p-diethylaminostyryl)-5-(p -diethylaminophenyl)pyrazoline, l-[pyridyl(2)]-3-(p-diethylaminostyryl)-4-methyl-5-(p-diethylaminophenyl)pyrazoline, 1-phenyl-3-
(p-diethylaminostyryl)-4-methyl-5-(
P-diethylaminophenyl) pyrazoline, spiropyrazoline and other pyrazolines, d-7enyl-4-N, N
-diphenylaminostilbene, N-ethyl-3(d-
phenylstyryl) carbazole, 9-dibenzylaminobenzylidene-9H-fluorenone, 5-p-ditolylaminobenzylidene-5H-dibenzo[a.

b] Styryl compounds such as cycloheptene, 2-(p-
diethylaminostyryl)-6-dinithylaminobenzoxazole 2-(p-diethylaminophenyl)-
Oxanol compounds such as 4-(p-dimethylaminophenyl)-5-(2-chlorophenyl)oxazole, thiazole compounds such as 2-(p-diethylaminostyryl)-6-dinithylaminobenzothiazole, bis(4- Triarylmethane compounds such as diethylamino-2-methylphenyl)-phenylmethane, 1.1
-bis(4-N,N-diethylamino-2methylphenyl)butane, 1,1,2.2tetrakis(4-N,N
Polyaryl alkanes such as -dimethylamino-2-methylphenyl)ethane, triphenylamine, poly-
N-vinylcarbazole, polyvinyl-ren, polyvinylanthracene, poly-nylacridine, poly-9-vinylanthracene, pyrene-formaldehyde resin, ethylcarbazole formaldehyde resin, and the like. In addition to these organic charge transport materials, there are selenium, selenium-tellurium, and amorphous silicon.

Collector materials such as cadmium sulfide may also be used.

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

When the charge transport material does not have film-forming properties, a film can be formed by selecting an appropriate binder. Examples of resins that can be used as binders include acrylic resin,
polyarylate, polyester, polycarbonate, polystyrene, acrylonitrile-styrene copolymer,
Insulating resins such as acrylonitrile-butadiene copolymer, polyvinyltutilal, polyvinyl formal, polysulfone, polyacrylamide, polyamide, chlorinated rubber, or organic photoconductive polymers such as poly-N-vinylcarhesol, polyvinylanthracene, polyvinylpyrene, etc. Can be mentioned.

Since the charge transport layer has a limit in its ability to transport charge carriers, it can only be made thicker than necessary. - The membrane has a length of 5 to 30 μm, with a preferred range of 8 to 20 m. When forming a charge transport layer by coating,
Any suitable coaching method, such as those described above, may 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 having a conductive layer. As such a substrate, the substrate itself may be conductive, such as aluminum, aluminum alloy, copper, zinc, stainless steel, vanadium, molybdenum, chromium, titanium, nickel, insium, gold or platinum. Plastics (e.g., polyethylene, polypropylene, polyvinyl chloride, polyethylene terephthalate, acrylic resin, polyfluoride (e.g. ethylene), substrates made of plastic coated with conductive particles (e.g. carbon black, silver particles, etc.) together with a suitable binder, substrates made of plastic or paper impregnated with conductive particles, and conductive polymers. It is also possible to use plastic, etc.

An undercoat layer having barrier and adhesive functions may be provided between the conductive substrate and the photosensitive layer. The undercoat layer is made of casein, polyvinyl alcohol, nitrocellulose, ethylene-acrylic acid copolymer polyamide, (nylon 6, nylon 66, nylon 610, copolymer nylon, alkoxymethylated nylon, etc.), polyurethane, gelatin, aluminum oxide, etc. It can be formed.

The thickness of the subbing layer is 0.1 to 5 gm, preferably 0.5 to 5 gm.
3ILm is appropriate.

When using a photoreceptor in which a conductive substrate, a charge generation layer, and a charge transport layer are laminated in this order, and the charge transport material is an electron transport material, it is necessary to positively charge the surface of the charge transport layer. When exposed to light, electrons generated in the charge generation layer are injected into the charge transport layer in the exposed area, and then reach the surface and neutralize the positive charges, causing a decrease in surface potential.
Electrostatic contrast occurs between the exposed area and the unexposed area.

A visible image is obtained by developing the electrostatic latent image thus formed with a negatively charged toner.

This can be directly fixed, or the toner image can be transferred to paper or plastic film and then developed and fixed.

Alternatively, a method may be used in which the electrostatic latent image on the photoreceptor is transferred onto an insulating layer of transfer paper, then developed and fixed. The type of developer, the developing method, and the fixing method may be any known ones or methods, and are not limited to specific ones.

On the other hand, when the charge transport material is a hole transport material, it is necessary to negatively charge the surface of the charge transport layer, and when exposed to light after charging, holes are generated in the charge generation layer in the exposed area and injected into the charge transport layer. , which then reaches the surface and neutralizes the negative charges, resulting in 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 when an electron transporting substance is used.

When using an electrophotographic photoreceptor in which a conductive substrate, 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. When exposed to light after charging, electrons generated in the charge generation layer are injected into the charge transport layer in the exposed area, and then reach the substrate. On the other hand, holes generated in the charge generation layer reach the surface, attenuation of the surface potential occurs, and electrostatic contrast occurs between the layer and the unexposed area. A visible image can be obtained by developing the electrostatic latent image thus obtained with positively charged toner. This can be directly fixed, or the toner image can be transferred to paper or plastic film, developed and fixed.

Alternatively, a method may be used in which the electrostatic latent image on the photoreceptor is transferred onto an insulating layer of transfer paper, then developed and fixed. The type of developer, the developing method, and the fixing method may be any known ones or methods, and are not limited to specific ones.

On the other hand, when it is made of a charge transport material or a hole transport material, 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 are injected into the charge transport layer in the exposed area. , then reaches the substrate. On the other hand, electrons generated in the charge generation layer reach the surface, attenuation of the surface potential occurs, and electrostatic contrast occurs between the layer and 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 another specific example of the present invention, there may be mentioned an electrophotographic photoreceptor in which the above-mentioned azo pigment is contained in the same layer together with a charge transport substance. In this case, a charge transfer complex compound consisting of poly-N-vinylcarhazole and trinitrofluorenone can be used in addition to the above-mentioned charge transport substance.

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

The pigment used in any electrophotographic photoreceptor contains at least one type of pigment selected from azo pigments represented by general formulas (1) and (2), and its crystal form is amorphous or crystalline. It may be.

In addition, if necessary, azo pigments represented by general formula (1) may be used in combination to increase the sensitivity of the photoreceptor or to obtain a panchromatic photoreceptor.
It is also possible to use a combination of more than one kind, or a combination with a charge generating substance selected from known dyes and pigments.

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

[Example] The present invention will be explained below using an example, but the present invention is not limited thereto.

Methoxymethylated nylon resin (
average molecular weight 32,000) 5 g, alcohol-soluble copolymerized nylon resin (average molecular weight 29,000) 10 g
was dissolved in 95 g of methanol and coated with a Mayer bar to form an undercoat layer having a dry film thickness of lpm.

Next, 15 g of the above-mentioned exemplified azo pigment No. (1) was added to cyclohexanone 951 with butyral resin (butyralization degree 6).
Add 2 g of 3 mol%) to the dissolved solution and grind with a sand mill
Spread out time. This dispersion was applied onto the previously formed undercoat layer using a Mayer bar so that the film thickness after drying was 0.21 Lm, and dried to form a charge generation layer.

Next, 5g of a hydrazone compound having the following structural formula is shown.

Table 1 Polymethyl methacrylate resin (number average molecular weight 1000
00) 5 g was dissolved in toluene 401, and applied onto the charge generation layer using a Mayer bar so that the film thickness after drying was 2011 m, and dried to form a charge transport layer. created a body.

Photoreceptors corresponding to Examples 2 to 17 were prepared in exactly the same manner using other exemplary pigments shown in Table 1 in place of azo pigment No. (1)-1.

The electrophotographic photoreceptor thus prepared was statically charged with corona at 15 kV using an electrostatic copying paper tester (Odel 5P-428 manufactured by Kawaguchi Denki ■), held in a dark place for 1 second, and then charged at an illuminance of 101. It was exposed to UV light and its charging characteristics were examined.

The charging characteristics include the surface potential (VO) and the exposure amount (E, 7
□) was measured. The results are shown in Table 1. Comparative Example 1 Same as Example 7 except that only the coupler component of the pigment used in Example 7 (Example (2)-8) was changed and a disazo pigment represented by the following structural formula was used. A photoreceptor was prepared and its charging characteristics were evaluated.

Va: 700 (-V), El/2:
4.5 (Iux-sec) From this result, it can be seen that all the electrophotographic photoreceptors of the present invention have sufficient charging ability and excellent sensitivity.

Using the electrophotographic photoreceptors prepared in Examples 3, 5, 7, and 9.16, fluctuations in bright area potential and dark area potential during repeated use were measured.

As a method, the photoreceptor was attached to the cylinder of an electrophotographic copying machine equipped with a -6.5 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 the cylinder is driven. Using this copying machine, the initial dark potential (VO) and light potential (Vt) were set to around -700V and -200V, respectively.
The amount of variation in dark area potential (ΔVO) and the amount of variation in light area potential (ΔvL) when used ooo times were measured. The result is the second
In the table, a negative sign in the amount of change in potential represents a decrease in the absolute value of the potential, and a positive sign represents an increase in the absolute value of the potential.

Table 2 Comparative Example 2 The photoreceptor prepared in Comparative Example 1 was measured for potential fluctuation during repeated use in the same manner as in Example 18. The results are shown below.

ΔVfl(V): -40, ΔVt,(V):
+50 From Example 20 and Comparative Example 2, it can be seen that the photoreceptor using the azo pigment of the present invention is stable with little potential fluctuation during repeated use.

A polyvinyl alcohol film having a thickness of 0.5 pm was formed on the aluminum surface of a uni-aluminum vapor-deposited polyethylene terephthalate film. Next, the azo pigment dispersion used in Example 7 was applied onto the previously formed polyvinyl alcohol layer using a Meyer bar so that the film thickness after drying was 0.2 gm, and dried to form a charge generation layer. did.

Next, 5 g of a styryl compound shown by the structural formula and a polyarylate resin (
A solution obtained by dissolving 5 g of a condensation polymer of bisphenol A and terephthalic acid-isophthalic acid) in tetrahydrofuran 401 was applied onto the charge generation layer so that the film thickness after drying was 20#Lm, and dried to form a charge transport layer. Formed. The charging characteristics of the photoreceptor thus prepared and the fluctuations in bright area potential and dark area potential upon repeated use were measured by the same method as in Examples 1 and 18. The results are shown below.

Vo: 705(-v), El/2: 0.8
(lux-sec) △Vo knee 5 (su, △V t,
: s (V) Hiou Wataramata A A photoreceptor was prepared by applying the charge generation layer and charge transport layer of the photoreceptor prepared in Example 7 in the reverse order, and the charging characteristics were evaluated in the same manner as in Example 1. did. The charging polarity was set to 10.

Vo: 710DV) + E l/2: 2.0
(lux-sec) 1. On the charge generation layer prepared in Example 7, 5 g of 2,4.7-dolinitro-9-fluorenone and poly-4,4°-
A solution prepared by dissolving 5 g of dioxydiphenyl-2,2°-propane carbonate (molecular weight 300,000) in monochlorobenzene 701 was coated and dried so that the film thickness after drying was 15 JLm.

The electrophotographic photoreceptor thus produced was evaluated in the same manner as in Example 1. However, the charging polarity was set to 10.

V, : 670 (+V), E I/2 : :1
．． 5 (Iux-sec) Example 26 2.4.7-Trinitro-9-fluorenone 5 g and poly-N-vinylcarbazole (number average molecular weight: 1 (IQ
OOO) 5 g was dissolved in tetrahydrofuran 701 to form a charge transfer complex compound. This charge transfer complex compound and 101 g of the above-mentioned exemplified azo pigment No. (2) were added to a solution in which 5 g of a polyester resin (Vylon, manufactured by Toyobo Co., Ltd.) was dissolved in tetrahydrofuran 701 and dispersed. This dispersion was applied onto the undercoat layer prepared in Example 1 and dried to form a photosensitive layer having a thickness of 16 μLm.

The photoreceptor thus produced was evaluated in the same manner as in Example 1. The charging polarity was set to 10.

Vo: 690 (+V), E, /,: 4.2
(Iux-sec) [Effect of the invention] By using the azo pigment of the invention in the photosensitive layer.

Either or both of the carrier generation efficiency and the injection effect inside the photoreceptor are improved, and a photoreceptor with excellent sensitivity and potential stability during repeated use can be obtained.

Claims (1)

[Claims] 1. In an electrophotographic photoreceptor having a photosensitive layer containing an azo pigment on a conductive support, the azo pigment has a general formula, ▲a mathematical formula, a chemical formula, a table, etc.▼(1) (In the formula, Ar represents a substituted or unsubstituted aromatic hydrocarbon group or a heterocyclic group which may be bonded via a bonding group, Cp represents a coupler residue having a phenolic hydroxyl group, and the Cp At least one is a coupler residue represented by the following general formula (2), n represents an integer of 1 to 4.) An electrophotographic photoreceptor characterized by being a compound represented by the following formula: , tables, etc. ▼(2) (wherein, represents an alkyl group, an aralkyl group, an aryl group, or a heterocyclic group which may have a substituent.) 2.Azo pigments have a general formula, ▲Mathematical formulas, chemical formulas, tables, etc.▼(3) (In the formula , Ar represents a substituted or unsubstituted aromatic hydrocarbon group or a heterocyclic group which may be bonded via a bonding group, and X is a polycyclic group fused with a benzene ring and which may have a substituent. Represents a residue necessary to form an aromatic ring or a heterocycle, R_1 represents an alkyl group, an aralkyl group, an aryl group, or a heterocyclic group that may have a substituent, n is an integer of 1 to 4 The electrophotographic photoreceptor according to claim 1, which is a compound represented by the following formula. 3. The electrophotographic photoreceptor according to claim 1, wherein the photosensitive layer containing an azo pigment comprises at least two layers: a charge transport layer and a charge generation layer containing an azo pigment represented by the general formula (1).