JPS63180960A - 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 each of R1 and R2 is H atom, alkyl or aralkyl group which may have a substituent or the like and X is a residue forming a polycyclic arom. or heterocyclic ring by condensation with a benzene ring). 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, and more particularly to an electrophotographic photoreceptor having a photosensitive layer containing an organic photoconductive substance consisting of a disazo pigment having a specific structure.

[Prior Art] Electrophotographic photoreceptors containing inorganic photoconductors such as selenium, cadmium sulfide, and zinc 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. moreover.

For example, as disclosed in U.S. Pat. No. 4,123,270, U.S. Pat. No. 4,247,614, U.S. Pat. No. 4,251,613, and U.S. Pat. No. 4,258,821, functional separation into a charge generation layer and a charge transport layer An electrophotographic photoreceptor using a photoconductive disazo pigment as a charge generating substance in a photosensitive layer is 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, for example, a group represented by any of the following general formulas (2) to (8).

General formula NO In the formula, R1 and R2 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 R1 and R2 are bonded. represents a group, or represents a residue that forms a polycyclic aromatic ring or a heterocycle by condensing with a benzene ring, and R3
and R4 represents an alkyl group, an aralkyl group, or an aryl group which may have a substituent, Y represents a divalent group of aromatic hydrocarbon or a divalent group forming a petro ring together with a nitrogen atom, and R5 and R6 represents a hydrogen atom, an alkyl group, an alkoxy group, a norogen 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 phenylene group and naphthylene group.

Representative examples of the disazo pigment represented by the general formula (1) are listed below.

Note that in the following basic types, only A is different, so only A is shown as an example.

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 formula using a conventional method, and coupling the resultant with 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 salt, 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 m beaker, 80 ml of water, 16.6 m of concentrated hydrochloric acid
m (0.19 mol) and 12.5 g of said diamine
(0,029 mol) was added and stirred while cooling 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 71 ml of water.
Add the solution dissolved in No. 11 over a period of 10 minutes while controlling the temperature within the range of 3 to 10"C. After the dropwise addition, stir at the same temperature for another 30 minutes. Add carbon to the reaction solution and sieve. A tetrazotized solution was obtained.

Next, pour 700ml of water into a beaker and add 2ml of caustic soda.
After dissolving 1 g (0.53 mol) of naphthol AS
(3-hydroxy-2-naphthoic acid anilide) 16.2
g (0,061 mol) was added and dissolved. This coupler solution was cooled to 6°C, and the above tetrazotized solution was added dropwise with stirring over 30 minutes while controlling the liquid temperature at 6 to 10°C.Then, the coupler solution was stirred at room temperature for 2 hours, and then left overnight. did.

The reaction solution was filtered and washed with water to obtain 24.0 g of a crude pigment.

Hot filtration was then repeated five times with 400 mJlj of N,N-dimethylformamide. Thereafter, 22.7 g of purified pigment was obtained by heat drying under reduced pressure.

The yield was 79.9%.

Elemental analysis: Calculated value (%) Experimental value (%) C73,5473,51 H3,813,78 N 12.86 12.83 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 in order to obtain sufficient light absorption, and in order to shorten the range of the generated charge carriers, it contains a coating, for example, 5 μm or less, preferably 0.01 to lpm. It is desirable to have a thin film.

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 generation layer can be formed, for example, by dispersing the 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 condensation polymers, etc.), 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 such as acetone, methyl ethyl ketone, cyclohexanone, N
, amides such as N-dimethylformamide and N,N-dimethylacetamide, sulfoxides such as dimethyl sulfoxide, and 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 blown air for a 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 formed as an a-layer on top of the charge generation layer, or may be laminated below it.

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

Pyrene, N-ethylcarbazole, N-isopropylcarbazole, N-methyl-N-
Phenylhydrazino-3-methylidene-9-ethylcarbazole, N,N-diphenylhydrazino-3-methylidene-9-ethylcarbazole, N,N-diphenylhydrazino-3-methylidene-10-ditylphenothiazine, 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-)
Limethylindolenine-ω-fuldehyde N, hydrazones such as N-diphenylhydrazone, 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, 1-phenyl-3-(p-dimethylaminostiri Jl/) -4-
Pyrazolines such as methyl-5-(p-diethylaminophenyl)pyrazoline, 2-(p-diethylaminostyryl)-6-dinithylaminobenzoxazole, 2-
Oxazole compounds such as (P-diethylaminophenyl)-4-(p-dimethylaminophenyl)-5-(2-chlorophenyl)oxazole, thiazoles such as 2-(P-diethylaminostyryl)-6-dinithylaminobenzothiazole triarylmethane compounds such as bis(4-diethylamino-2-methylphenyl)-phenylmethane, 1,1-bis(4-N,N
-diethylamino-2-methylphenyl)hebutane, 1
, 1,2.2-tetrakis(4-N,N-dimethylamino-2-methylphenyl)ethane and other polyarylalkanes, triphenylamine, poly-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 materials can be used alone or in combination of two or more.

When the charge transport material does not have sufficient 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 formal, polysulfone, polyacrylamide, polyamide, chlorinated rubber, and base 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 pm, but the preferred range is 8 to 207 pm.
It is zm. 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, platinum, etc. are used.

In addition, plastics (e.g., polyethylene, polypropylene, polyvinyl chloride, polyethylene terephthalate, acrylic resin, (polyfluorinated ethylene, etc.), 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, plastics containing conductive polymers, etc. can be used.

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 m, preferably 0.5 to 3 m.

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, causing a decrease in surface potential and creating an electrostatic contrast between it and the unexposed area. arise. 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, when the charge transport material is made of a hole transport material, the surface of the charge transport layer must be negatively charged, and when exposed to light after charging, holes generated in the charge generation layer are injected into the charge transport layer in the exposed area. , which then reaches the surface and neutralizes the negative charges, resulting in attenuation of the surface potential and an electrostatic contrast between the surface potential and the unexposed area. 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)
Examples include an electrophotographic photoreceptor in which an organic photoconductor, which is a disazo pigment represented by the formula, is contained in the same layer together with the above-mentioned charge transport material.

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
1.2 g, 28% ammonia water 1 g, water 222 li)
was applied with a Mayer bar so that the film thickness after drying was 1.0 pm, 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 JLm, and dried to form a charge generation layer.

5g of hydrazone compound and polymethyl methacrylate (
5 g (number average molecular weight: 100,000) was dissolved in 70 rsl of benzene, and this was coated with Mayer birch onto the charge generation layer so that the film thickness after drying was 12 pm, and dried 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 set at an illuminance of 2 cm UX. It was exposed to light and its charging characteristics were examined.

The charging characteristics are 1 surface level (Vo) and the exposure amount (E) required to attenuate the potential to 1/2 when dark decayed for 1 second.
l/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 amount of 5 mux, sec, 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 (CVo) after 5,000 uses were measured. The results are shown below.

Vony 610V, El/2: 3.0JLux, early sec
Examples 2 to 15 after 5,000-sheet durability Electrophotographic photoreceptors were prepared in the same manner as in Example 1, except that the following exemplified pigments were used in place of the exemplified pigments used 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.

2 (,1) 3 (3)2
600 2.73
610 2.94 61
0 3.25 615
3.16 610
3.37 Boo
2.88 605 2
, 79 610'
3.210 620 3.4
11 610 3.01 2
600 2, 813
620 3.214
620 3.315
625 3.1 Example 16 On the charge generation layer prepared in Example 1, 2,4.7-)
! A coating solution prepared by dissolving 5 g of J Nitro 9-fluorenone and 5 g of poly-4,4-dioxydiphenyl-2,2-propane carbonate (molecular weight 300,000) in 70 ml of tetrahydrofuran has a coating amount of 10 g 7 m2 after drying. Apply it and let it dry.

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: +600V, El/2: 8.3JluX, see, initial VD: +805V, VL: +40V After 5,000 sheets durability Vo: +625V, VL: +80V Example 17 Film thickness 1 on the aluminum surface of aluminum vapor-deposited polyethylene terephthalate film ．． A polyvinyl alcohol film of OILm was formed.

Next, the dispersion of the exemplary pigment (7) 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 0.5 lm, and then dried. A charge generation layer was formed.

Then 1-[quinolyl(2)]-3-(p-diethylaminostyryl)-5-(p-diethylaminophenyl)
5g of pyrazoline and 5g of polyarylate resin (11 polymers of bisphenol A and terephthalic acid-isophthalic acid)
A solution obtained by dissolving 100 ml of 100 ml of tetrahydrofuran in 70 ml of tetrahydrofuran was applied onto the charge generating layer so that the film thickness after drying was loILm, and dried to form a charge transporting 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.

VONY 620V.

El/2: 3.2JLux, sec.

Initial Vo knee 620V, VL knee 35V, after 5,000 sheets durability VD knee 655V, VL knee 75V Example 18 Thickness 100. An ammonia aqueous solution of casein is applied onto a GM aluminum plate and dried to a film thickness of 1. A subbing layer of OILm was formed.

Next, 5 g of 2,4.7-)dinitro-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 rsn 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 rrrl and dispersed. This dispersion was applied onto the undercoat layer so that the film thickness after drying was 12 JLm, 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: +615V.

E 1/2: 6, 5 ux, sec.

[Effects of the Invention] By using a disazo pigment with a specific structure in the photosensitive layer, the electrophotographic photoreceptor of the present invention can improve carrier generation efficiency, carrier transport efficiency, or both in the photosensitive layer containing the disazo pigment. It is estimated that this will result in 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 .