JPH012058A - electrophotographic photoreceptor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a novel electrophotographic photoreceptor, and more particularly to an electrophotographic photoreceptor containing a disazo pigment having a specific molecular structure in its photosensitive layer. It is related to.

[Conventional technology]

As shown in U.S. Pat. No. 2,297,691, electrophotography is a photoconductive method consisting of a support coated with an insulating material in the dark whose electrical resistance changes depending on the amount of radiation received during image exposure. Use materials. The basic characteristics required of an electrophotographic photoreceptor using this photoconductive material are (1) ability to be charged to an appropriate potential in a dark place; (2)
(3) The charge can be quickly dissipated by light irradiation.

Conventionally, inorganic photoreceptors having photosensitive layers mainly composed of inorganic photoconductive compounds such as selenium, zinc oxide, and cadmium sulfide have been widely used as electrophotographic photoreceptors. Although conditions (3) to (3) are satisfied, they are not necessarily satisfactory in terms of thermal stability, moisture resistance, durability, etc. For example, when selenium crystallizes, its properties as a photoreceptor deteriorate, so Also, heat, fingerprints, etc. can cause crystallization, which deteriorates the performance of the photoreceptor. Cadmium sulfide has moisture resistance and durability, and zinc oxide has smoothness and hardness.

There is a problem with abrasion resistance. Furthermore, many inorganic photoreceptors have a limited photosensitive wavelength region. For example, selenium has a sensitive wavelength region in the blue region and has almost no sensitivity in the red region. For this reason, various methods have been proposed to extend the photosensitivity to longer wavelength regions, but there are many restrictions on the selection of the sensitive wavelength region. Even when zinc oxide or cadmium sulfide is used as a photoreceptor, its sensitivity wavelength range is narrow and it is necessary to add various sensitizers.

In order to overcome these drawbacks of inorganic photoreceptors, electrophotographic photoreceptors containing various organic photoconductive compounds as main components have been actively developed in recent years.

For example, Japanese Patent Publication No. 50-10496 and U.S. Pat. No. 3,484,237 disclose a photoreceptor having a photosensitive layer containing poly-N-vinylcarbazole and 2.4.7-) dinitrofluorenone-9-one; There is one in which N-vinylcarbazole is sensitized with a pyrylium salt dye (Japanese Patent Publication No. 48-25658).

Although these organic electrophotographic photoreceptors have improved the drawbacks of the inorganic electrophotographic photoreceptors to some extent, they generally have low photosensitivity and are not suitable for repeated use. In order to overcome these drawbacks, various photoreceptors have been proposed as organic electrophotographic photoreceptors in recent years. , a charge generation layer), and a layer (hereinafter referred to as a charge transport material) mainly consisting of a substance that accepts charge carriers generated by the charge generation layer and transports them (hereinafter referred to as a charge transport material).
Some laminated photoreceptors consisting of a charge transport layer (referred to as a charge transport layer) are in practical use because they generally have higher sensitivity than conventional organic electrophotographic photoreceptors and can withstand repeated use.

For example, U.S. Pat. No. 3,837,851 discloses a photoreceptor having a charge generation layer and a charge transport layer containing triallylpyrazoline, and U.S. Pat. Examples include a photoreceptor comprising a charge transport layer made of a condensate of formaldehyde.

Further, photoreceptors using bisazo pigments or trisazo pigments as charge generating substances are disclosed in JP-A-59-33445, JP-A-56-46237, and JP-A-60-11.
Publication No. 1249 and the like are already known.

However, these bisazo pigments or trisazo pigments do not necessarily satisfy the characteristics of sensitivity, residual potential, or stability during repeated use, and the selection range of charge transport materials is also limited, which meets the wide demands of electrophotographic processes. It does not fully satisfy.

[Problem that the invention seeks to solve]

It is an object of the present invention to provide a new photoconductive material.

A second object of the present invention is to provide an electrophotographic photoreceptor that has practical high sensitivity characteristics in the visible region and stable potential characteristics upon repeated use.

A third object of the present invention is to provide an electrophotographic photoreceptor that is compatible with charge transport materials having a high oxidation potential.

[Means for solving problems]

That is, the present invention is an electrophotographic photoreceptor having a photosensitive layer on a conductive support, characterized in that the photosensitive layer contains a disazo pigment represented by the following formula (1).

-Formula R1 A -N=N-Ar-N-Ar'N=N-A'
(1) - Ar and Ar' in formula (1) represent a divalent aromatic hydrocarbon ring group or an aromatic heterocyclic group which may have a substituent, and may be the same or different. .

Phenylene is an aromatic hydrocarbon ring group.

Naphthylene, anthracenylene, phenanthrylene, etc. are mentioned, and aromatic heterocyclic groups include pyridinediyl,
Examples include quinolinediyl and the like.

Substituents for the aromatic hydrocarbon ring group and aromatic heterocyclic group include halogen groups such as fluorine, chlorine, bromine, and iodine;
Substitution of alkyl groups such as methyl, ethyl, propyl, isopropyl, butyl, alkoxy groups such as methoxy, ethoxy, propoxy, phenoxy, nitro group, cyano group, dimethylaminodibenzylamino, diphenylamino, morpholino, pea veridino, pyrrolidino, etc. Examples include amino groups.

R1 represents a lower alkyl group having up to 3 carbon atoms having two or more halogen atoms, or a cyano group, specifically, a difluoromethyl group, a trifluoromethyl group, 1,1.1
- Trifluoroethyl group, 1,1゜1-trichloroethyl group, 1,1.1-trifluoroisopropyl group, 2,2.2-trifluoropropyl group, etc.

A and A' in the general formula (1) represent coupler residues having a phenolic OH group, and more preferable specific examples of the coupler residues represented by A and A' include the general formula % formula % formula (2) The middle X is condensed with a benzene ring to form a polycyclic aromatic ring or a heterocycle such as a naphthalene ring, anthracene ring, carbazole ring, benzcarbazole ring, dibenzofuran ring, dipenzonaphthofuran ring, diphenylene sulfide ring, etc. Residues required for are shown.

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

In formula (2), R2 and R3 represent a hydrogen atom, an alkyl group which may have a substituent, an aryl group, an aralkyl group, a heterocyclic group, or a cyclic amino group together with the nitrogen atom to which R2 and R3 are bonded.

Specific examples of alkyl groups include methyl, ethyl, propyl, butyl, etc. Specific examples of aralkyl groups include benzyl, phenethyl, naphthylmethyl, etc. Specific examples of aryl groups include phenyl, diphenyl, naphthyl, anthryl, etc. Specific examples of the heterocyclic group include carbazole, dibenzofuran, benzimidacylone, benzthiazole, thiazole, pyridine and the like.

R4 in formulas (3) and (4) represents a hydrogen atom, an alkyl group that may have a substituent, an aryl group, or an aralkyl group. A specific example of R4 is shown by the same example as R3 and R4 above.

The alkyl group, aryl group, aralkyl group, alkoxy group, and heterocyclic group represented by the substituents R2 to R4 in formulas (2) to (4) may further include other substituents such as halogen groups such as fluorine, chlorine, iodine, and bromine. , alkyl groups such as methyl, ethyl, propyl, isopropyl, butyl, methoxy, ethoxy,
Alkoxy groups such as propoxy and phenoxy, nitro groups,
It may be substituted with a substituted amino group such as a cyano group, dimethylamino, dibenzylamino, diphenylamino, morpholino, piperidino, and pyrrolidino.

H In formulas (5) and (6), Y represents a divalent aromatic hydrocarbon group or a heterocyclic divalent group containing a nitrogen atom in the ring.

Examples of divalent groups of aromatic hydrocarbons include divalent groups of monocyclic aromatic hydrocarbons such as 0-phenylene, condensed polyesters such as 0-naphthylene, perinaphthylene, 1,2-antrylene, and 9.10-phenanthrylene. Divalent groups of cyclic aromatic hydrocarbons are mentioned. Also, 2 of a heterocycle containing a nitrogen atom in the ring
As the valent group, 3,4-pyrazolediyl group, 2,3
-pyridinediyl group, 4,5-pyrimidinediyl group, 6
．． Divalent groups such as 7-indazolediyl group and 6°7-chiralindiyl group can be mentioned.

R5 in formula (7) represents an aryl group or a heterocyclic group which may have a substituent, and specifically represents a phenyl, naphthyl, anthryl, pyrenyl, pyzylyl, thienyl, furyl, or carbazolyl group.

Substituents for the aryl group and heterocyclic group represented by R5 include halogen groups such as fluorine, chlorine, iodine, and bromine, methyl,
Alkyl groups such as ethyl, propyl, isopropyl, butyl, alkoxy groups such as methoxy, ethoxy, propoxy, phenoxy, nitro group, cyano group, dimethylamino,
Examples include substituted amino groups such as dibenzylamino, diphenylamino, morpholino, piperidino, and pyrrolidino.

A specific example of X is shown by the same example as X in formula (2).

R6 and R7 in formula (8) represent a hydrogen atom, an alkyl group, an aryl group, an aralkyl group, or a heterocyclic group which may have a substituent, specifically methyl, ethyl, propyl, butyl, Indicates benzyl, phenethyl, naphthylmethyl, phenyl, naphthyl, anthryl, diphenyl, carbazole, dibenzofuran, benzimidacylone, benzthiazole, thiazole, and pyridine.

Substituents for the alkyl group, aryl group, aralkyl group, and heterocyclic group represented by R6 and R7 in formula (8) include halogen groups such as fluorine, chlorine, iodine, and bromine, methyl, ethyl, propyl, isopropyl, butyl, and the like. an alkyl group,
Examples include alkoxy groups such as methoxy, ethoxy, propoxy, and phenoxy, and substituted amino groups such as nitro group, cyano group, dimethylamino, dibenzylamino, diphenylamino, morpholino, piperidino, and pyrrolidino.

The following are already known as bisazo pigments having a diphenylamine skeleton as a central skeleton, which are related to the present invention.

Cp indicates a coupler residue.

These bisazo pigments are not necessarily satisfactory in terms of sensitivity, residual potential, or stability during repeated use. The present inventor believes that one of these causes is the strong donor nature of the central skeleton of the pigment, and the structure of the central skeleton of the pigment causes the ionization potential of the pigment molecule itself to be small (which may affect sensitivity and other characteristics). In addition, these pigments can only achieve high sensitivity when combined with a charge transfer material with a low oxidation potential.
Since a charge transport material with a high oxidation potential cannot be used, there are problems in terms of durability and the like.

However, the electrophotographic photoreceptor using the disazo pigment according to the present invention has an alumium halide as an N-substituent on the central skeleton. By introducing an electron-withdrawing group consisting of a cyano group, the central skeleton can be made more acceptor-like than an unsubstituted or electron-donating substituent, or even a weak electron-withdrawing group such as an acetyl group. For this purpose, when the disazo pigment according to the present invention is used as a charge generation layer,
A charge transport substance with a high oxidation potential (Box (V) = 0.
70 or higher), and achieved high sensitivity. Among the alkyl halides, the trifluoromethyl group is particularly effective.

In addition, charge transport substances with high oxidation potential (E ox (V )
= 0, 70 or more) can now be used,
It has excellent chemical stability against ozone oxidation caused by corona discharge on the surface of the electrophotographic photoreceptor, and is particularly able to maintain potential stability during repeated cycles.

The oxidation potential of the charge transport substance refers to the peak value (E ox ) of the first oxidation wave, and in reality, methanol, ethanol, acetonitrile, etc. are used as the solvent, and tetra-n-butylammonium perchlorate, It can be measured by cyclic voltammetry using salts such as lithium perchlorate and tetraethylammonium p-toluene and using a saturated calomel electrode as an electrode. However, the measurement is not limited to this method, and can also be determined by botensiometry or polarography.

In the present invention, the oxidation potential was measured by cyclic voltammetry using acetonitrile as a solvent, tetra-n-butylammonium perchlorate as a supporting electrolyte, and a saturated calomel electrode as an electrode.

A general method for producing the disazo pigment of general formula (1) used in the present invention will be described. When A and A' are the same in the disazo pigment represented by the general formula (1), the following general formula (9
) is converted into a tetrazonium salt by a conventional method using sodium nitrite or nitrosyl sulfate, and aqueous coupling is performed with the coupler components A and A', or the obtained tetrazonium salt is converted into a borofluoride salt, etc. It can be obtained by extracting it as a stable salt and then coupling it in an organic solvent such as dimethylformamide. If A and A' are different, during the coupling reaction, first perform coupling with the first coupler component, form a monoazo form, and then perform coupling with the second coupler component,
It can be obtained by using a disazo pigment or by mixing two coupler components and performing a coupling reaction. Furthermore, as another method, it can also be obtained by the following method.

General formula (9) R1 % formula % Here, Ar, Ar' and R1 represent the same meanings as in claim (1).

That is, an acetylamino compound represented by the general formula (IO) is diazotized, and a coupler having a phenolic hydroxyl group and R are formed.

CH, C0NH-Ar-N-Ar'-NH2(10
) After coupling, it is hydrolyzed with a mineral acid such as hydrochloric acid or an alkali such as sodium hydroxide to form an amino compound H2N-Ar-N-A' -N=N-Cp (Cp is a coupler residue having a phenolic hydroxyl group) ),
A preferred method is to diazotize again and couple with another coupler residue to obtain an asymmetric pigment.

Next, specific examples of the disazo pigment used in the present invention are listed below. However, these disazo pigments will be described below as typical synthesis examples of the disazo pigments used in the present invention.

Synthesis Example 1 (Synthesis of the aforementioned exemplified azo pigment No. 1) 30
0 m I! 100ml of water and 24ml of concentrated hydrochloric acid in a beaker
I! (0.27 mol) was added, and after cooling in an ice-water bath, 11.0 g (0,041 mol) of N-trifluoromethyl-4,4'-diphenylamine was added, and the liquid temperature was brought to 3°C with stirring. .

1 Next, add 6.0 g (0,087 mol) of sodium nitrite to 10 mI of water! was added dropwise over a period of 10 minutes while controlling the liquid temperature to 5° C. or less, and after the addition was completed, the mixture was further stirred at the same temperature for 30 minutes. After adding activated carbon to the reaction solution and filtering, 13.5 g of sodium borofluoride (0,123
mole) of water 20 m j! The precipitated borofluoride salt was collected by filtration, washed with water, and then dried in vacuum. Yield 15.4g Yield 81.0% Next II! D in beaker
Add 200 ml of MF and add 2.81 ml of 2-hydroxy-3-naphthoic acid-2'-fluoroanilide.
g (0.01 mol) was dissolved, the liquid temperature was cooled to 5°C,
After dissolving 4.65 g (o, oi mol) of the borofluoride salt obtained earlier, 1.02 g (0,01 mol) of triethylamine was dissolved.
mol) was added dropwise over 10 minutes, followed by stirring for 2 hours. After filtering the reaction solution, N,N-dimethylformamide 20
0 m! ! The mixture was washed four times with acetone, replaced with acetone, and dried under vacuum to obtain the desired azo pigment No. 1. Yield 7.2
6g Yield 85.2% (based on borofluoride salt) Elemental analysis calculated value Actual value C66,27% 66.35% H3,55% 3.50% N 11.51% 11.59% General formula (1 The coating containing the disazo pigment of ) exhibits photoconductivity and can therefore be used in the photosensitive layer of an electrophotographic photoreceptor.

That is, in the present invention, the general formula (1) is formed on the conductive support.
An electrophotographic photoreceptor can be constructed by forming a film using the disazo pigment described above by vacuum evaporation, or by forming a film by dispersing the disazo pigment in a suitable binder.

In a preferred embodiment of the present invention, the above-mentioned film exhibiting photoconductivity may be 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. can.

The charge generation layer contains as much of the above-mentioned photoconductive compound as possible in order to obtain sufficient absorbance, and is a thin film layer, for example -5 μm or less, in order to shorten the range of the generated charge carriers. Preferably, it is a thin film layer having a thickness of 0.01 to 1 μm. 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.

As described above, the charge generation layer can be formed, for example, by dispersing the disazo pigment of the formula (1) in a suitable binder and coating it on the support, or by forming a vapor deposited film using a vacuum vapor deposition device. You can also get it by doing 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 butyral, polyarylate (condensation polymer of bisphenol A and phthalic acid, etc.), polycarbonate, polyester, phenoxy resin, polyvinyl acetate, acrylic resin, polyacrylamide resin, polyamide, polyvinylpyridine, cellulose resin, urethane resin. , epoxy resin, casein, polyvinyl alcohol, polyvinylpyrrolidone, and other insulating resins. 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 is preferably selected from those that do not dissolve the underlying charge transport layer or subbing layer.

Specific organic solvents include methanol, ethanol,
Alcohols such as isopropanol, ketones such as acetone, methyl ethyl ketone, cyclohexanone, N
, amides such as N-dimethylformamide and N,N-dimethylacetamide, sulfoxides such as dimethyl sulfoxide, ethers such as tetrahydrofuran, dioxane, and ethylene glycol monomethyl ether, esters such as methyl acetate and ethyl acetate, chloroform, and chloride. Aliphatic halogenated hydrocarbons such as methylene, dichloroethylene, carbon tetrachloride, trichlorethylene, etc., or aromatics such as benzene, toluene, xylene, ligroin, monochlorobenzene, dichlorobenzene, etc. can be used.

Coating can be performed using a coating method such as a dip coating method, a spray coating method, a Meyer bar coating method, a blade coating method, 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 at a temperature of 30°C to 200°C
It can be carried out stationary or under blown air for times ranging from minutes to 2 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 located on a side farther from the charge generation layer when viewed from the conductive support (or may be located between the conductive support and the charge generation layer). .

Charge transport substances in the charge transport layer include electron transport substances and hole transport substances, and electron transport substances include chloranil, bromoanil, tetracyanoethylene, tetracyanoquinodimethane, and 2,4.7- Dolinitro 9-fluorenone, 2, 4. Electrons such as 5.7-tetranitro-9-fluorenone, 2.4.7-)dinitro-9-dicyanomethylenefluorenone, 2.4.5.7-titranitroxanthone, 2,4.8-)linitrothioxanthone, etc. These include absorbing substances and polymerized materials of these electron-attracting substances.

Examples of hole-transporting substances include pyrene, N-ethylcarbazole, N-inpropylcarbazole, N-methyl-N
-Phenylhydrazino-3-methylidene-9-ethylcarbazole, N,N-diphenylhydrazino-3-methylidene-9-ethylcarbazole, N,N-diphenylhydrazino-3-methylidene-10-ditylphenothia Zine, N,N-diphenylhydrazino-3-methylidene-10-ethylphenoxazine, p-diethylaminobenzaldehyde-N, N-diphenylhydrazone, p-diethylaminobenzaldehyde-N-α-naphthyl-N-phenylhydrazone, p- Pyrrolidinobenzaldehyde-N,N-diphenylhydrazone, 1.3
．． 3-trimethylindolenine-ω-aldehyde-N,
Hydrazones such as N-diphenylhydrazone, P-diethylbenzaldehyde-3-methylbenzthiazolinone-2-hydrazone, 2,5-bis(p-diethylaminophenyl)-1,3,4-oxadiazole, l
-phenyl-3-(p-diethylaminostyryl)-5
-(p-diethylaminophenyl)pyrazoline, 1-[
quinolyl (2)]-3-(p-diethylaminostyryl)-5-(p-diethylaminophenyl)pyrazoline,
1-[pyridyl (2)) -3-(p-diethylaminostyryl)-5-(p-diethylaminophenyl)pyrazoline, 1-[6-medoxypyridyl (2)) -3-
(p-diethylaminostyryl)-5-(p-diethylaminophenyl)pyrazoline, 1-[pyridyl (3)
]-3-(p-diethylaminostyryl)-5-(p-
diethylaminophenyl)pyrazoline, l-[levidyl (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, l-phenyl-3
-(α-benzyl-p-diethylaminostyryl)-5
-(p-diethylaminophenyl)pyrazoline, spiropyrazoline and other pyrazolines, a-phenyl-4-N
, N-diphenylaminostilbene, N-ethyl-3(
α-phenylstyryl)carbazole, 9-p-dibenzylaminobenzylidene-9H-fluorenone, 5-p
-Ditolylaminobenzylidene-5H-dibenzo (a,
d) Styryl compounds such as cycloheptene, 2-(p
-diethylaminostyryl)-6-dinithylaminobenzoxazole, 2-(p-diethylaminophenyl)
-4-(p-dimethylaminophenyl)-5-(2-chlorophenyl>, t-+oxazole compounds such as sasol, 2-(p-diethylaminostyryl)-6-
Thiazole compounds such as dinithylaminobenzothiazole, bis(4-diethylamino-2-methylphenyl)
-Triarylmethane compounds such as phenylmethane, 1
．． l-bis(4-N,N-diethylamino-2-methylphenyl)heptane, l, 1.2.2-tetrakis(
4-N.

Polyarylalkanes such as N-dimethylamino-2-methylphenyl)ethane, triphenylamine, poly-
Examples include N-vinylcarbazole, polyvinylpyrene, polyvinylanthracene, polyvinylacridine, poly-9-vinylphenylanthracene, pyrene-formaldehyde resin, and ethylcarbazole formaldehyde resin.

In addition to these organic charge transport materials, inorganic materials such as selenium, selenium-tellurium amorphous silicon, and cadmium sulfide can 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, polyvinyl butyral, polyvinyl formal, polysulfone, polyacrylamide, polyamide, chlorinated rubber, or organic photoconductive polymers such as poly-N-vinylcarbazole, polyvinylanthracene, polyvinylpyrene, etc. be able to.

The charge transport layer cannot be made thicker than necessary because there is a limit to its ability to transport charge carriers. Generally, the thickness is 5 to 40 μm, but the preferable range is 15 to 3 μm.
It is 0 μm. 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 conductive support.

As the conductive support, the support itself is conductive, such as aluminum, aluminum alloy, copper, zinc,
Stainless steel, vanadium, molybdenum, chromium, titanium, nickel, indium, gold, platinum, etc. can be used, and in addition, aluminum, aluminum alloy, indium oxide, tin oxide, indium oxide-tin oxide alloy, etc. can be coated by vacuum evaporation method. Plastics having formed layers (e.g. polyethylene, polypropylene, polyvinyl chloride, polyethylene terephthalate, acrylic resins, supports coated on plastics or metal supports mentioned above, supports impregnated with conductive particles in plastic or paper) or plastics containing conductive polymers.

A subbing layer having barrier and adhesive functions can also be provided between the conductive support and the photosensitive layer. The subbing layer is made of 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 subbing layer is 0.05 to 5 μm, preferably 0.5 μm.
~3 μm is appropriate.

In another specific example of the present invention, the above-mentioned hydracines,
Organic photoconductive substances such as pyrazolines, styryl compounds, oxazoles, thiazoles, triarylmethanes, polyarylalkanes, triphenylamine, poly-N-vinylcarbazoles, zinc oxide, cadmium sulfide, selenium, etc. A photosensitive film can be obtained which contains the disazo pigment of general formula (1) described above as a sensitizer for an inorganic photoconductive substance. This photosensitive film is formed by coating these photoconductive substances and the disazo pigment of general formula (1) described above together with a binder.

Another specific example of the present invention is an electrophotographic photoreceptor containing the above-mentioned disazo pigment of general formula (1) together with a charge transport material in the same layer.

At this time, in addition to the above-mentioned charge transport substance, a charge transfer complex compound consisting of poly-N-vinylcarbazole and trinitrofluorenone can be used. The electrophotographic photoreceptor of this example can be prepared by dispersing the disazo pigment of general formula (1) and the charge transfer complex compound in a solution of polyester dissolved in tetrahydrofuran, and then forming a film thereon.

The pigment used in any of the photoreceptors is selected from disazo pigments represented by the general formula (1). In addition, if necessary, the disazo pigment represented by the 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 printers, CRT printers, L
It can also be widely used in electrophotographic applications such as ED printers, liquid crystal printers, and laser engraving.

〔Example〕

Hereinafter, the present invention will be explained by examples.

Examples 1 to 9 A 0.1 μm undercoat layer made of vinyl chloride-maleic anhydride-vinyl acetate copolymer resin was provided on an aluminum plate.

Next, 3.5 g of the above-mentioned exemplary disazo pigment No. was added to 95 m I! of cyclohexanone. The mixture was added to a solution in which 2 g of butyral resin (degree of butyralization: 63 mol %, number average molecular weight: 20,000) was dissolved, and dispersed in a sand mill for 2 hours.

This dispersion was applied onto the previously formed subbing layer using a Mayer bar so that the film thickness after drying was 0.2 μm, and dried to form a charge generation layer. Next, as a charge transport material, charge transport material No. 11, 5 g of benzylidene compound, and polymethyl methacrylate resin (number average molecular weight 1,100,000) were added.
5 was dissolved in 70 ml of chlorobenzene, and this was applied onto the charge generation layer using a Mayer bar so that the film thickness after drying would be 20 μm, and dried to form a charge transport layer.
A photoreceptor was created.

The electrophotographic photoreceptor produced in this way was manufactured by Kawaguchi Electric Co., Ltd.
Corona charging was carried out at -5.5 KV in a static manner using an electrostatic copying paper testing device Model 5P-428 manufactured by Manufacturer.
After being held in a dark place for 1 second, it was exposed to light at an illuminance of 2 A'ux, and the charging characteristics were examined.

As for the charging characteristics, the surface potential (vo) and the exposure amount (EK) required to attenuate the potential to 1 when dark decayed for 1 second were measured. Similarly, disazo pigment No. 3. 10
．． Regarding 22, charge transport material No., (11), (12
) and (13) to produce photoreceptors corresponding to Examples 2 to 9, and measured in the same manner. The results are shown in Table 1, and the oxidation potential Eox (V) of the charge transport material is shown in Table 2.

Table 1 Table 2 Comparative Examples 1 to 12 In place of the disazo pigments of Examples 1 to 9, disazo pigments having the following structural formulas (comparative pigment Nos. 1 to 3) were used, and Example 1
In addition to the charge transport materials of Examples 1 to 9, a hydrazone compound of structural formula (14) was used to prepare and evaluate photoreceptors in the same manner as in Examples 1 to 9. The results are shown in Table 3.

Comparative Example 1 corresponds to Example 11, Comparative Example 2 corresponds to Example 6, and Comparative Example 3 corresponds to Example 11. The disazo pigment of the comparative example has high sensitivity when combined with a charge transfer substance with a low oxidation potential. However, it can be seen that when combined with a substance having a high oxidation potential, the sensitivity becomes low, but when combined, the sensitivity is excellent.

Table 3 Examples 9 to 20 In place of the disazo pigments in Examples 1 to 9, disazo pigment N
o, 4.6.7.8.13.15. 17. 18.2
B.

A photoreceptor was prepared and evaluated in the same manner as in Example 1 using Sample Nos. 34 and 38. The results are shown in Table 4.

Table 4 Examples 21-24 Example 1.9. 12. Using the photoreceptor used in 16,
Fluctuations in bright area potential and dark area potential were measured during repeated use. The method is to attach the photoreceptor to the cylinder of an electrophotographic copying machine equipped with a -5.6KV corona charger, exposure optical system, developer, transfer charger, static elimination exposure optical system, and cleaner. The structure is such that an image is obtained on the transfer paper as the transfer unit is driven. Using this copying machine, the initial bright area potential (Vt, ) and dark area potential (Vo)
are set around -100V and -600V, respectively, and
Bright area potential (Vt) and dark area potential (v
o) was measured. The results are shown in Table 5.

Example 25 On the charge generation layer prepared in Example 1, 5 g of 2,4,7-trinitro-9-fluorenone and poly-4,4'-dioxydiphenyl-2,2'-propane carbonate (
molecular weight 300,000) 5g to tetrahydrofuran 7
0mj! A coating solution prepared by dissolving the solution was applied so that the coating amount after drying was 10 g/-, and then dried.

The electrostatic charge of the electrophotographic photoreceptor thus produced was measured in the same manner as in Example 1. At this time, the charging polarity was set to ten.

The results are shown below.

vo: ■675 Volt E! 4: 5.91 ux*sec Example 26 A polyvinyl alcohol film having a thickness of 0.5 μm was formed on the aluminum surface of an aluminum vapor-deposited polyethylene terephthalate film. Next, the disazo pigment dispersion used in Example 1 was applied onto the previously formed polyvinyl alcohol layer using a Mayer bar so that the film thickness after drying was 0.2 μm, and dried to form a charge generation layer. did.

Next, 5 g of a hydrazone compound of structural formula (12) (Box (V) = 0
．． 57) and bisphenol 2 type polycarbonate resin (
Viscosity average molecular weight 30000) 5g of monochlorobenzene 32.5mI! A solution dissolved in the above was applied onto the charge generation layer so that the thickness after drying was 20 μm, and dried to form a charge transport layer. The charging characteristics and durability characteristics of the photoreceptor thus prepared were measured in the same manner as in Example 21. The results are shown in Table 6.

Vo: C) 605 volts E14: 2.5 l1ux*sec Table 6 (
Durability Characteristics) Results in Table 6 - Better sensitivity and good potential stability during long-term use.

Example 27 Soluble nylon (6-6
A 5% methanol solution of 6-610-12 quaternary nylon copolymer) was applied and dried to form a subbing layer with a thickness of 0.5 μm.

Next, 2.4.7-) 5 g of Rinitro-9-fluorenone and poly-N-vinylcarbazole (number average molecular weight 3000
00) was dissolved in 70 mji' of tetrahydrofuran to form a charge transfer complex compound. This charge transfer complex compound and the above-mentioned disazo pigment No. 13 1 g were mixed with 5 g of polymethyl methacrylate-styrene copolymer resin (molecular weight 250,000) in 70 m of tetrahydrofuran.
j! It was added to the solution dissolved in and dispersed. This dispersion was applied onto the undercoat layer and dried to prepare a 20 μm photoreceptor.

The charging characteristics of the photoreceptor thus prepared were measured in the same manner as in Example 1. The results are shown below. However, the charging polarity was set to ■.

■. :■57eV E! 4: 7.5 fux*sec Example 28 The charge transport layer and charge generation layer of Example 1 are sequentially laminated on the nylon layer of the aluminum base coated with the nylon layer used in Example 1, with different layer configurations. Except for this, a photoreceptor was formed in the same manner as in Example 1, and the charging characteristics were measured in the same manner as in Example 1. However, the charging polarity was set to Φ.

The results are shown below.

■. :■575v EH: 3.5 I! ux*sec [Effect of the Invention] According to the present invention, by using a specific disazo pigment in the photosensitive layer, either one or both of the carrier generation efficiency and the carrier transport efficiency inside the photosensitive layer can be improved. As a result, an electrophotographic photoreceptor with high sensitivity and durability, especially excellent potential stability during long-term use, is constructed.

Claims (1)

[Scope of Claims] (1) An electrophotographic photoreceptor having a photosensitive layer on a conductive support, characterized in that the photosensitive layer contains a disazo pigment represented by general formula (1). . General formula ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (1) [In the formula, A and A' are phenolic coupler residues,
They may be the same or different. Ar and Ar' represent a divalent aromatic hydrocarbon ring group or an aromatic heterocyclic group which may have a substituent, and may be the same or different. R_1 represents a lower alkyl group having up to 3 carbon atoms and having two or more halogen atoms, or a cyano group. ] (2) The electrophotographic photoreceptor according to claim (1), wherein A and A' in general formula (1) are represented by the following general formula (2). General formula ▲ Numerical formula, chemical formula, table, etc. ▼ (2) In formula (2), X represents a residue necessary to form a polycyclic aromatic ring or a heterocycle by condensation with a benzene ring. In formula (2), R_2 and R_3 represent a hydrogen atom, an alkyl group that may have a substituent, an aryl group, an aralkyl group, a heterocyclic group, or a cyclic amino group together with the nitrogen atom to which R_2 and R_3 are bonded. (3) The electrophotographic photoreceptor according to claim (1), wherein A and A' in general formula (1) are represented by the following general formula (3). General formula ▲ Numerical formula, chemical formula, table, etc. ▼ (3) R_4 in formula (3) represents a hydrogen atom, an alkyl group that may have a substituent, an aryl group, or an aralkyl group. (4) The electrophotographic photoreceptor according to claim (1), wherein A and A' in general formula (1) are represented by the following general formula (4). General formula ▲ Numerical formula, chemical formula, table, etc. ▼ (4) R_4 in formula (4) represents a hydrogen atom, an alkyl group that may have a substituent, an aryl group, or an aralkyl group. (5) The electrophotographic photoreceptor according to claim (1), wherein A and A' in general formula (1) are represented by the following general formula (5). General formula ▲ Numerical formula, chemical formula, table, etc. ▼ (5) Y in formula (5) represents a divalent group of an aromatic hydrocarbon or a divalent group of a heterocyclic ring containing a nitrogen atom in the ring. (6) The electrophotographic photoreceptor according to claim (1), wherein A and A' in general formula (1) are represented by the following general formula (6). General formula ▲ Numerical formula, chemical formula, table, etc. ▼ (6) Y in formula (6) represents a divalent group of an aromatic hydrocarbon or a divalent group of a heterocyclic ring containing a nitrogen atom in the ring. (7) The electrophotographic photoreceptor according to claim (1), wherein A and A' in general formula (1) are represented by the following general formula (7). General formula ▲ Numerical formula, chemical formula, table, etc. ▼ (7) In formula (7), R_5 represents an aryl group or a heterocyclic group that may have a substituent, and X is fused with a benzene ring to form a Represents residues necessary to form an aromatic ring or a heterocycle. (8) The electrophotographic photoreceptor according to claim (1), wherein A and A' in general formula (1) are represented by the following general formula (8). General formula ▲ Numerical formula, chemical formula, table, etc. ▼ (8) In formula (8), R_6 and R_7 are hydrogen atoms, alkyl groups that may have substituents, aryl groups, aralkyl groups, or heterocyclic groups shows. X represents a residue necessary to form a polycyclic aromatic ring or a heterocycle by condensation with a benzene ring. (9) The photosensitive layer has a laminated structure of a charge generation layer and a charge transport layer, the charge generation layer contains a disazo pigment represented by the general formula (1), and the charge transport layer has an oxidation potential of The electrophotographic photoreceptor according to claim (1), which contains a charge transport material with a voltage of 0.7 (V) or more.