JPS63180961A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To obtain an electrophotographic sensitive body having high sensitivity and maintaining stable electrostatic charge characteristics even after repeated use by incorporating at least one kind of specified disazo pigment as a photoconductor into a photosensitive layer formed on an electrically conductive substrate. CONSTITUTION:At least one kind of disazo pigment represented by formula 1 as a photoconductor is incorporated into a photosensitive layer formed on an electrically conductive substrate. In the formula 1, A is a coupler residue having phenolic OH group or a coupler residue of a 2-methylindolenine deriv., e.g., a group represented by formula 2 (where Y is a bivalent arom. hydrocarbon group or a bivalent group forming a heterocyclic ring together with N, e.g., phenylene or naphthyl group). Thus, a sensitive body having high sensitivity and superior potential stability during repeated use is obtd.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to an electrophotographic photoreceptor, specifically an electrophotographic photoreceptor containing a photosensitive layer containing a photoconductive material made of a disazo pigment having a specific structure. Regarding.

[Conventional Technique #7] Electrophotographic photoreceptors containing inorganic photoconductors such as selenium, cadmium sulfide, and lead oxide in the photosensitive layer are well known. On the other hand, organic photoconductive polymers, carbazoles, such as, for example, poly-N-vinylcarbazole, polyvinylanthracene.

Low-molecular organic photoconductors such as anthracene, pyrazolines, oxadiazoles, and hydrazones, phthalocyanine pigments, azo pigments, and indigo dyes.

Organic photoconductors such as thioindigo dyes and methine squaric acid dyes have been developed. Further, for example, US Pat. No. 4,123,270, US Pat. No. 42,476
As disclosed in U.S. Pat. No. 14, U.S. Pat. No. 4,251,813, U.S. Pat. Electrophotographic photoreceptors using disazo pigments are known.

An electrophotographic photoreceptor using such an organic photoconductor can be produced using a coating method by dip coating by appropriately selecting a binder, so that a photoreceptor with extremely high productivity and low cost can be provided.

Moreover, although it has the advantage of being able to select an organic pigment that exhibits photoconductivity in an appropriate wavelength range, it has drawbacks in sensitivity and durability against repeated use, and so far only a few have been put into practical use.

[Problems to be Solved by the Invention] An object of the present invention is to provide an electrophotographic photoreceptor containing a novel organic photoconductor in its photosensitive layer.

Still another object is to provide an electrophotographic photoreceptor that has high sensitivity for practical use and exhibits stable charging characteristics even after repeated use.

[Means and effects for solving the problems] The present invention is characterized in that a photosensitive layer provided on a conductive substrate contains at least one type of disazo pigment represented by the following general formula (1) as a photoconductor. It consists of an electrophotographic photoreceptor.

General Formula (1) In the formula, A represents a coupler residue having a phenolic OH group or a coupler residue of a 2-methylindolenine derivative.

More specifically, the coupler residue A in the above general formula (1) is a group represented by, for example, any one of the following general formulas (2) to (8).

general formula N.

In the formula, R1 and R2 are a hydrogen atom, an alkyl group which may have a substituent, an aralkyl group, an aryl group, a heterocyclic group, an imino group, or a cyclic amino group together with the nitrogen atom to which R, R2 is bonded. , X represents a residue condensed with a benzene ring to form a polycyclic aromatic ring or a heterocycle, and R3
and R4 represents an alkyl group, aralkyl group, or aryl group which may have a substituent, and Yl represents a divalent group of an aromatic hydrocarbon or a divalent group forming a heterocycle with a nitrogen atom; R5 and R6 represent a hydrogen atom, an alkyl group, an alkoxy group, a halogen atom, a cyano group or a nitro group.

In the above definitions, examples of alkyl groups, aralkyl groups, aryl groups, alkoxy groups and heterocyclic groups include alkyl groups such as methyl, ethyl and propyl; aralkyl groups such as benzyl and naphthylmethyl; and aryl groups such as phenyl. , diphenyl, naphthyl, anthryl, etc.; examples of alkoxy groups include methoxy, ethoxy, propoxy, etc.; examples of heterocyclic groups include dibenzofuran, benzimidacylon, benzthiazole, thiazole, pyridine, etc.

Substituents for the above alkyl groups, aralkyl groups, aryl groups, alkoxy groups, heterocyclic groups and imino groups include, for example, halogen atoms, nitro groups, cyano groups, substituted amino groups (e.g. dimethylamino, diphenylamino, dibenzylamino, etc.) , an alkyl group, an alkoxy group, and the like.

Examples of residues that form a polycyclic aromatic ring or heterocycle with the benzene ring of Can be mentioned.

Further, examples of the divalent group of Y include a phenylene group and a naphthylene group.

Hereinafter, the disazo face represented by the general formula (1) will be shown as an example since only A is different in the following basic types.

Nυ These disazo pigments can be used alone or in combination of two or more.

These disazo pigments can be obtained by, for example, tetrazotizing the diamine represented by the following in a conventional manner, and coupling thereto a coupler having a group represented by the corresponding general formulas (2) to (8) above in the presence of an alkali. Alternatively, once the tetrazonium salt of the diamine described above is isolated in the form of a borofluoride salt or a zinc chloride double ring, a suitable solvent such as N,N-dimethylformamide,
It can be easily produced by coupling with a coupler having a group represented by the corresponding general formulas (2) to (8) above in the presence of an alkali in a solvent such as dimethyl sulfoxide.

Synthesis example of exemplified pigment (1) 500 11141 F knee car 1c water 80 ml
, 1llfJi acid 16.6 rn sentence (0,19 mol)
Then, 12.9 g (0,029 mol) of the above-mentioned diamine was added, and the mixture was stirred while being cooled in an ice-water bath to bring the liquid temperature to 3°C.

Next, add 4.2 g (0,061 mol) of sodium nitrite to 7 ml of water.
The solution dissolved in an was added dropwise over 10 minutes while controlling the temperature within the range of 3 to 10"C. After the dropwise addition was complete, the solution was stirred at the same temperature for an additional 30 minutes. Carbon was added to the reaction solution and filtered to form tetrazotization. I got the liquid.

Next, put 700 mff1 of water into a 2-liter beaker, dissolve 21 g (0.53 mol) of caustic soda, and then add naphthol A.
s (3-hydroxy-2-naphthoic acid anilide) 16
．． 2g (0,061 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 tetrazotized solution was added dropwise with stirring over 30 minutes, then stirred at room temperature for 2 hours, and further left overnight. .

The reaction solution was filtered and washed with water to obtain 25.2 g of a crude pigment.

Then hot filtration was carried out with 400+Jl of N,N-dimethylpolamide. Thereafter, 22.4 g of purified pigment was obtained by heat drying under reduced pressure.

The yield was 78%.

Elemental analysis: Calculated value (%) Experimental value (%) C73,7873,75 H3,653,63 N 11.28 11.25 The film containing the disazo pigment represented by the general formula (1) has photoconductive properties. Therefore, it can be used in the photosensitive layer of an electrophotographic photoreceptor.

The electrophotographic photoreceptor is prepared by forming a film of the disazo pigment on a conductive substrate by vacuum evaporation, or by dispersing the disazo pigment in a suitable binder to form a film.

In a preferred embodiment of the present invention, the photoconductive coating described above can be 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.

The charge generation layer contains as much photoconductive material as possible to obtain sufficient light absorption, and is coated with a coating, for example, 5 μm or less, preferably 0.01 to 1 μm, to shorten the range of the generated charge carriers. It is desirable to form a thin film with a thickness of m.

This means that most of the incident light is absorbed by the charge generation layer and generates a large number of charge carriers, and that the generated carriers must be injected into the charge transport layer without being deactivated by recombination or trapping. It is caused by something.

The charge generating layer can be formed, for example, by dispersing the above-mentioned disazo pigment in a suitable binder and coating it on a substrate, or by forming a vapor deposited film using a vacuum vapor deposition apparatus. The binder that can be used to form the charge generating layer by coating can be selected from a wide variety of insulating resins, and can also be selected from organic photoconductive polymers such as poly-N-vinylcarbazole, polyvinylanthracene, and polyvinylpyrene. Preferably polyvinyl butyral, polyarylate (bisphenol A
and phthalic acid), polycarbonate, polyester, phenoxy resin, polyvinyl acetate, acrylic resin, polyacrylamide, polyamide, polyvinylpyridine, cellulose resin, polyurethane, epoxy resin, casein, polyvinyl alcohol, polyvinylpyrrolidone, etc. Examples include 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 charge transport layer and undercoat layer described below.

Specific organic solvents include methanol, ethanol,
Alcohols such as isopropanol, ketones a and N such as acetone, methyl ethyl ketone, and cyclohexanone
, amides such as N-dimethylpolamide 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, aliphatic halogenated hydrocarbons such as chloroform, methylene chloride, dichloroethylene, carbon tetrachloride, and trichloroethylene, or benzene and toluene.

Aromatic hydrocarbons such as 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, or a spinner coating method.

Drying is preferably carried out by drying to the touch at room temperature and then heating. Drying by heating is performed at a temperature of 30 to 200°C for 5 minutes to
It can be carried out stationary or under ventilation for a period of time in the range of 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. At this time, this charge transport layer may be laminated on or under the charge generation layer.

Charge transporting substances include electron transporting substances and hole transporting substances, and electron transporting substances include chloranil, bromoanil, tetracyanoethylene, tetracyanoquinodimethane, 2,4.7-dolinitro-9-fluorenone, 2
,4,5.7-tetranitro-9-fluorenone,2,
4.7-1 nitro-9-dicyanomethylene fluorenone, 2.4,5.7-titranitroxanthone, 2,4
．． Examples include electron-withdrawing substances such as 8-trinidrothioxanthone, and polymerization of these electron-withdrawing substances.

Examples of hole-transporting substances include pyrene, N-ethylcarbazole, N-isopropylcarbazole, and N-methyl-N-
Phenylhydrazino-3-methylidene-9-ethylcarbazole, N,N-diphenylhydrazino-3-methylidene-9-ethylcarbazole, N,N-diphenylhydrazino-3-methylidene-10-ethylphenothiazine, N,N -diphenylhydrazino-3-methylidene-
10-Ethylphenoxazine, p-diethylami/benzaldehyde-N, N-diphenylhydrazone, p-diethylaminobenzaldehyde-N-α-naphthyl-N
-Hydrazones such as phenylhydrazone, P-pyrrolidinohenzaldehyde N, N-diphenylhydrazone, p-diethylbenzaldehyde-3-methylbenzthiazolinone-2-hydrazone, 2.5-bis(P-diethylaminophenyl) -1,3,4-oxadiazole, 1-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, 1-[pyridyl(2)]-3-(p-diethylaminostyryl)-4-methyl-5-(p-diethylaminophenyl)pyrazoline, l-pheny/l/
-3-(p-diethylaminostyryl)-4-l-
Pyrazolines such as 5-(p-diethylaminophenyl)pyrazoline and spiropyrazoline, 2-(p-diethylaminostyryl)-6-dinithylaminobenzoxazole, 2-(p-diethylaminophenyl)-4-(p
Oxazole compounds such as -dimethylaminophenyl)-5-(2-chlorophenyl)oxazole, 2-(
Thiazole compounds such as P-diethylaminostyryl)-6-ethylaminobenzothiazole, bis(4-
Triarylmethane compounds such as diethylamino-2-methylphenyl)-phenylmethane, 1,1-bis(
Polyarylalkanes such as 4-N,N-diethylamino-2-methylphenyl)hebutane, 111.2.2-tetrakis(4-N,N-dimethylamino-2-methylphecol)ethane, triphecolamine , poly-N-
Examples include vinylcarbazole, polyvinylpyrene, polyvinylanthracene, polyvinylacridine, poly-9-vinylphenylanthracene, birene-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 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. Examples of resins that can be used as binders include acrylic resin,
polyarylate, polyester, polycarbonate, polystyrene, acrylonitrile-styrene copolymer,
Examples include insulating resins such as acrylonitrile-butadiene copolymer, polyvinyl butyral, polyvinyl alcohol, polysulfone, polyacrylamide, polyamide, and chlorinated rubber, and organic photoconductive polymers such as poly-N-vinylcarbazole polyvinylanthracene and polyvinylpyrene.

The charge transport layer has a limit in its ability to transport charge carriers, so it cannot be made thicker than necessary. Generally, the thickness is 5 to 30 pLm, but the preferred range is 8 to 20 pLm.
It is pLm. 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 having a conductive layer. Examples of the substrate having a conductive layer include those whose substrate itself is conductive, such as aluminum, aluminum alloy, copper, zinc,
Stainless steel, vanadium, molybdenum, chromium, titanium, nickel, indium, gold, and platinum are used.

In addition, plastics (e.g., polyethylene, polypropylene, polyvinyl chloride, polyethylene terephthalate, acrylic resin, polyfluoride, (ethylene chloride, etc.), conductive particles (e.g. carbon black silver particles, etc.) coated on plastic together with a suitable binder, conductive particles impregnated into plastic or paper, or conductive polymer-containing plastics. be able to.

A subbing layer having barrier and adhesive functions can also be provided between the conductive layer and the photosensitive layer. The subbing layer can be formed from casein, polyvinyl alcohol, nitrocellulose, ethylene-acrylic acid copolymer, polyamide (nylon 6, nylon 66, nylon 610, copolymerized nylon, alkoxymethylated nylon, etc.), polyurethane, gelatin, aluminum oxide, etc. . The appropriate thickness of the undercoat layer is 0.1 to 5 pm, preferably 0.5 to 3 #Lm.

When using a photoreceptor in which a conductive layer, a charge generation layer, and a charge transport layer are laminated in this order, and the charge transport material is an electron transport material, the surface of the charge transport layer must be positively charged, and exposure after charging is required. Then, in the light band area, electrons generated in the charge generation layer are injected into the charge transport layer, and then reach the surface and neutralize the positive charge, resulting in an attenuation of one surface type, creating an electrostatic contrast between it and the unexposed area. occurs. 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, and then visualized 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, if the charge transport material is a hole transport material, the surface of the charge transport layer must be negatively charged.

After charging, when exposed to light, holes generated in the charge generation layer in the exposed area are injected into the charge transport layer, and then reach the surface and neutralize the negative charge, causing a decrease in surface potential and a gap between the exposed area and the unexposed area. Electrostatic contrast occurs. During development, it is necessary to use a positively charged toner, contrary to when an electron transporting substance is used.

Furthermore, as another specific example of the present invention, the above general formula (1)
One example is an electrophotographic photoreceptor in which a disazo pigment represented by the above-mentioned photoconductor is contained in the same layer together with the charge transporting substance described above.

At this time, a charge transfer complex compound consisting of polyvinylcarbazole and trinitrofluorenone can be used as the charge transport substance.

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

In any of the electrophotographic photoreceptors, the pigment used contains at least one type of pigment selected from disazo pigments represented by the general formula (1), and if necessary, pigments with different light absorptions are used in combination to sensitize the material. General formula (1) is used for the purpose of increasing the sensitivity of the body or obtaining a panchromatic photoreceptor.
It is also possible to use a combination of two or more kinds of disazo pigments represented by the above, or a combination with a charge generating substance selected from known dye pigments.

The electrophotographic photoreceptor of the present invention can be used not only in electrophotographic copying machines, but also in a wide range of electrophotographic applications such as laser printers and CRT printers.

[Example] Example 1 Ammonia aqueous solution of casein (casein 1
1.2g, 28% ammonia water 1g, water 222+nJl
) was applied with a Mayer bar so that the film thickness after drying was 1.0 lm, and dried.

Next, 5 g of the organic photoconductor of the exemplified pigment (7) was added to ethanol 95+JL with butyral resin (butyralization degree 6).
Add 2 g of 3 mol%) to the solution and add 2 g with an attritor
Spread out time. This dispersion was applied onto the previously formed casein layer using a Mayer bar so that the film thickness after drying was 0.5 pm, and dried to form a charge generation layer.

5g of hydrazone compound and polymethyl methacrylate (
A charge transport layer was formed by dissolving 5 g of the polymer having a number average molecular weight of 100,000 in 70 μm of benzene, and applying the solution onto the charge generation layer using a Mayer bar so that the thickness after drying would be 12 μm, and drying to form a charge transport layer.

The electrophotographic photoreceptor thus prepared was statically charged with corona at 15 KV using an electrostatic copying paper tester [5P-428 (turntable)], held in a dark place for 1 second, and then exposed to light at an illuminance of 21 ux. , the charging characteristics were investigated.

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

Furthermore, in order to measure the fluctuations in bright area potential and dark area potential when repeatedly used, the electrophotographic photoreceptor prepared above was used.
It was attached to the cylinder of an electrophotographic copying machine equipped with a 5.6 KV corona charger, an exposure optical system with an exposure dose of 5 uX, 5 eC, a developing device, 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.

Using this copying machine, the initial bright area potential (VL) and dark area potential (VD) and the bright area potential (VL) and dark area potential (Vo) after 5,000 uses were measured. The results are shown below.

Vony 600V, El/2: 2.41ux, sea Initial After 5,000 sheets durability Examples 2 to 15 All of the following examples were used in place of the exemplified pigments used in Example 1, except that the following exemplified pigments were used. An electrophotographic photoreceptor was prepared in the same manner as in Example 1.

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

Show the results.

862 590, 2.33
580 2, 64
600 2, 5
5 595 2.46
610 2, 57
605 2, 78
590 2, 49
595 2, 6
10 600 2.811
610 2.512
600 2.413
615 2.314
620 2.715 61
0 2.9 Example 16 On the charge generation layer prepared in Example 1, 5 g of 2,4.7-dolinitro-9-fluorenone and poly-4,4-dioxydiphenyl-2,2-propane carbonate (molecular weight A coating solution prepared by dissolving 5 g of 300,000 mm) in 70 mfL of tetrahydrofuran was applied so that the coating amount after drying was 10 g 7 m 2 and dried.

The charging characteristics of the electrophotographic photoreceptor thus prepared were measured in the same manner as in Example 1. At this time, the charge was set to 10. Show the results.

vo: +580V, E1/2: 4.71ux, sec.

Initial Vo: +585V, VL: +30V After 5,000 sheets durability VD: +595V, ML: +55V Example 17 A film thickness of 1.5V was deposited on the aluminum surface of an aluminum vapor-deposited polyethylene terephthalate film. A polyvinyl alcohol film of OJLm was formed.

Next, the dispersion of the exemplary pigment (7) used in Example 1 was applied onto the polyvinyl alcohol layer formed earlier using a Mayer bar so that the film thickness after drying would be 0.5 gm, and dried. A charge generation layer was formed.

Then 1-[quinolyl(2)]-3-(p-diethylaminostyryl)-5-(p-diethylaminophenyl)
A solution prepared by dissolving 5 g of pyrazoline and 5 g of polyarylate resin (condensation polymer of bisphenol A and terephthalic acid-isophthalic acid) in 701 g of tetrahydrofuran was placed on the charge generation layer so that the film thickness after drying would be io#Lm. Apply,
It was dried to form a charge transport layer.

The charging characteristics and durability characteristics of the electrophotographic photoreceptor thus prepared were measured in the same manner as in Example 1. Show the results.

vonie 810V, E1/2: 2.6uux, sec.

Initial Vo knee 610V, VL knee 35V After 5,000 sheets durability Vn knee 640V, VL knee 50V Example 18 An ammonia ammonia solution of casein was applied onto a 1100 JL thick aluminum plate and dried to a film thickness of 1. A subbing layer of Opm was formed.

Next, 5 g of 2,4.7-dolinitro-9-fluorenone
A charge transfer complex compound was prepared by dissolving 5 g of poly-N-vinylcarbazole (number average molecular weight: 300,000) in 70 ran of tetrahydrofuran.

Photoconductor 1 of this charge transfer complex compound and exemplary pigment (19)
g, 5 g of polyester resin and 70 g of tetrahydrofuran.
It was added to the solution dissolved in ml and dispersed. This dispersion was applied onto the undercoat layer so that the film thickness after drying was 127 zm, and dried.

Example 1 Charging characteristics of the electrophotographic photoreceptor thus prepared
It was measured in the same manner as.

However, the charging polarity was set to 10. Show the results.

vo: +590V, E1/2: 4.81uX*5e
C1 [Effect of the Invention] By using a disazo pigment with a specific structure in the photosensitive layer, the electrophotographic photoreceptor of the present invention improves either or both carrier generation efficiency and carrier transport efficiency within the photosensitive layer containing the disazo pigment. It is estimated that this will improve the performance, and it will have remarkable effects such as high sensitivity and excellent potential stability during long-term use.

Claims (3)

[Claims] (1) The following general formula (
An electrophotographic photoreceptor comprising at least one of the disazo pigments shown in 1) as a photoconductor. General formula (1) ▲ Numerical formulas, chemical formulas, tables, etc. are available▼ In the formula, A represents a coupler residue having a phenolic OH group or a coupler residue of a 2-methylindolenine derivative. (2) The electrophotographic photoreceptor according to claim 1, wherein the coupler residue A in the general formula (1) is a coupler residue selected from the groups represented by the following general formulas (2) to (8). General formulas ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (2) ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (3) ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (4) ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼(5) ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (6) ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (7) ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (8) In the formula, R_1 and R_2 are A hydrogen atom, an alkyl group that may have a substituent, an aralkyl group, an aryl group, a heterocyclic group, an imino group, or a cyclic amino group together with the nitrogen atom to which R_1 and R_2 are bonded, and X is fused with a benzene ring. represents a residue forming a polycyclic aromatic ring or a heterocycle, R_3 and R_4 represent an alkyl group, an aralkyl group, or an aryl group that may have a substituent, and Y represents a divalent aromatic hydrocarbon. It represents a divalent group that forms a heterocycle with a group or a nitrogen atom, and R_5 and R_6 represent a hydrogen atom, an alkyl group, an alkoxy group, a halogen atom, a cyano group, or a nitro group. (3) The photosensitive layer is a laminated photosensitive layer consisting of a charge generation layer and a charge transport layer, and the charge generation layer has the general formula (1).
Claim 1 containing a disazo pigment represented by
The electrophotographic photoreceptor described in .