JPH0480382B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD The present invention relates to a laminated electrophotographic photoreceptor, and more particularly, the present invention relates to an electrophotographic photoreceptor in which at least a charge transport layer and a charge generation layer are successively laminated on a conductive support, and the surface layer of the photoreceptor is a charge generation layer. Regarding photoreceptors. BACKGROUND ART Electrophotographic photoreceptors using inorganic photoconductors such as selenium, cadmium sulfide, and zinc oxide as photosensitive components have been known. On the other hand, since it was discovered that certain organic compounds exhibit photoconductivity, many organic photoconductors have been developed. For example, organic photoconductive polymers such as poly-N-vinylcarbazole and polyvinylanthracene, carbazole, anthracene, pyrazolines, oxadiazoles, hydrazones,
Organic pigments and dyes such as low-molecular organic photoconductors such as polyarylalkanes, phthalocyanine pigments, azo pigments, cyanine dyes, polycyclic quinone pigments, perylene pigments, indigo dyes, thioindigo dyes, or methine squaritate dyes are used. Are known. In particular, organic pigments and dyes with photoconductivity are easier to synthesize than inorganic materials, and the variety of compounds that exhibit photoconductivity in an appropriate wavelength range has expanded. Photoconductive organic pigments and dyes have been proposed. For example, U.S. Patent Nos. 4123270, 4247614, 4251613, 4251614, 4256821,
Same No. 4260672, Same No. 4268596, Same No. 4278747,
As disclosed in No. 4,293,628, electrophotographic photoreceptors are known in which a disazo pigment exhibiting photoconductivity is used as a charge-generating substance in a photosensitive layer that is functionally separated into a charge-generating layer and a charge-transporting layer. In particular, with regard to azo pigments, there are many variations in materials, and research has been active in recent years, and several have been put into practical use. In its use, it has a structure in which a charge generation layer and a charge transport layer are laminated in this order on a conductive support, and the charge transport material used in the charge transport layer is a material with strong electron donating properties to improve hole transport properties. It was common practice to charge the photoreceptor to a high level. Reasons for this include the fact that there are almost no electron-transporting materials with excellent properties, and that they are carcinogenic and cannot be used due to pollution concerns. When negative corona discharge is performed, a large amount of ozone is generated, and an ozone filter must be attached to the main body of the copying machine, resulting in an increase in costs. Furthermore, as the ozone filter gradually deteriorates over the years, periodic maintenance such as filter replacement is required. Furthermore, negative corona discharge tends to cause discharge unevenness due to dirt on the discharge wire, etc., which causes image unevenness. The ozone generated also has a negative effect on the durability life of the OPC. During charging, a large amount of ozone is generated, causing problems such as material deterioration on the surface of the photoreceptor and adhesion of ionic substances generated by corona charging to the photoreceptor. This causes local or total image blurring or image defects in copied images formed by electrophotography. On the other hand, positive corona discharge generates 1/5 to 1/10 the amount of ozone compared to negative corona discharge.
Therefore, uneven discharge due to dirt or the like on the discharge wire is unlikely to occur. It is also extremely advantageous in terms of photoreceptor life. As described above, charging has many disadvantages, and there is an urgent need to develop a charged photoreceptor. One way to make a charged laminated photoreceptor is to form a charge transport layer with hole transport properties on a conductive support.
This is achieved by sequentially stacking charge generation layers. However, when the thickness of the charge generation layer is increased, carriers generated by light become more likely to be trapped within the charge generation layer, resulting in larger optical memory and increased bright area potential during repeated use. Therefore, it is customary to have an extremely thin film thickness of about 0.1 to 0.5 μm. However, when the charge-generating layer is on the surface layer of the photoreceptor, charging, image exposure, development, transfer of the toner image to a transfer member such as paper or plastic film, separation of the transfer member from the photoreceptor, cleaning, and before and after cleaning. If such a photoreceptor is used in copying methods such as static elimination, the surface layer of the photoreceptor will be scratched during processes such as development, transfer, cleaning, etc. where parts come into contact with the photoreceptor. The current problem is that the change in sensitivity becomes extremely large, and in extreme cases, the charge generation layer is scratched and no longer exhibits sensitivity. Problems to be Solved by the Invention The first object of the present invention is to provide a highly sensitive electrophotographic photoreceptor for charging, in which at least a charge transport layer and a charge generation layer are sequentially laminated on a conductive support. . A second object of the present invention is to provide an electrophotographic photoreceptor for charging, which has improved electrophotographic properties and has at least a charge transport layer and a charge generation layer sequentially laminated on a conductive support. A third object of the present invention is to provide an electrophotographic photoreceptor for charging, which has improved durability and has at least a charge transport layer and a charge generation layer laminated in sequence on a conductive support. Means for Solving the Problems, Actions, and Effects of the Invention The object of the present invention is to sequentially stack at least a hole-transporting charge transport layer and a charge generation layer on a conductive support. This is accomplished by incorporating a photoconductive azo pigment and a specific hole transporting charge transport material. It is believed that the reason why a particular charge transport material must be selected is that there is selectivity in carrier injection from the photoconductive azo pigment, which is the carrier generating material, to the charge transport material in the charge generating layer. If an attempt is made to increase the physical strength of the photoconductor surface by increasing the amount of binder resin in the charge generation layer, the transportability of the carrier in the charge generation layer will be significantly reduced, resulting in decreased sensitivity, deterioration of optical memory, and brightness during long-term use. This usually resulted in an increase in the potential of the parts. However, by incorporating a specific hole-transporting charge transporting material into the charge generation layer, it has become possible to ensure sufficient carrier transportability within the charge generation layer even when the amount of binder is increased.
Therefore, the physical strength of the photoreceptor surface is strong, and the sensitivity and
A photoreceptor with excellent optical memory can be obtained. Furthermore, abrasion of the photosensitive layer during long-term use is significantly reduced, and a photoreceptor with less change in sensitivity during long-term use can be achieved, thereby achieving the object of the present invention. As the photoconductive azo pigment used in the present invention, an azo pigment having a phenolic OH group is used, and more specifically, an azo pigment represented by the general formula A(-N=N-B) () is particularly effective. It is. In the formula, 2 or 3 is shown. In the formula, A is a divalent organic group or a divalent organic group in which the carbon atoms to which the azo group is bonded form a conjugated double bond system.

It is characterized by being represented by the following formula. A specific example of a divalent organic group is etc. can be mentioned. R ₁ to _{R 28} are hydrogen, halogens such as chlorine, bromine, and iodine; alkyl groups such as methyl, ethyl, and propyl; alkoxy groups such as methoxy and ethoxypropoxy; aralkyl groups such as benzyl and phenethyl;
Indicates a nitro group, a cyano group, etc. X is -O-, -S-,

[Formula] is shown. R ₂₉ represents hydrogen, the above-mentioned alkyl groups, aralkyl groups, and aryl groups such as phenyl and naphthyl. Specific examples of divalent organic groups include the general formulas (1) to
Also included is a group represented by (8) in which a phenylazo group, which may have a substituent, is attached to both ends. m and n represent 0 or 1, and may be the same or different. In the general formula (), B represents a coupler having a phenolic OH group, and more specifically, etc. are particularly effective. In the general formula (10), Y represents a residue necessary to form a polycyclic aromatic ring or a heterocycle such as a naphthalene ring, anthracene ring, carbazole ring, benzcarbazole ring, dibenzofuran ring, etc. by condensation with a benzene ring. Z in the general formulas (13) and (14) represents a divalent aromatic hydrocarbon group or a heterocyclic divalent group containing an N atom in the ring. R ₃₀ to _{R 32} represent an alkyl group, an aralkyl group, or an aryl group represented by R ₁ to _{R 29} . The aryl group and the aryl group in the aralkyl group further include an alkyl group, an alkoxy group, a nitro group, a cyano group, as shown by R ₁ to R ₂₉ .
It may be substituted with a halogen, an aralkyl group, an aryl group, or a substituted amino group such as dimethylamino, diethylamino, and dibenzylamino. The specific hole-transporting material used in the charge generation layer of the present invention is a hydrazone-based charge-transporting material, and a particularly preferable material among the hydrazones is represented by the following general formula. In the formula, D represents a phenyl group which may have a substituent other than the substituted amino group, or a carbazolyl group which may have a substituent other than the N substituent. Specifically, D is

【formula】

【formula】

Selected from [Formula]. R and R' in the general formula () represent an alkyl group such as methyl, ethyl, propyl, butyl, an aralkyl group such as benzyl or phenethyl, an aryl group such as phenyl, α-naphthyl, β-naphthyl, etc. The aryl group in the aralkyl group is chlorine,
Even when substituted with halogens such as bromine and iodine, alkyl groups such as methyl, ethyl, and propyl, alkoxy groups such as methoxy, ethoxy, and propoxy, and substituted amino groups such as dimethylamino, diethylamino, dipropylamino, and dibenzylamino. good. In formulas (17) to (19), R ₃₃ , R ₃₄ , and R ₄₀ have the same meanings as the alkyl, aralkyl, and aryl groups represented by R and R', and R ₃₅ to _{R 39} and R ₄₁ represent methyl and ethyl groups. ,
Alkyl groups such as propyl, methoxy, ethoxy,
Indicates alkoxy groups such as propoxy, and halogens such as chlorine, bromine, and iodine. Specific examples of the hydrazone compound used in the present invention are shown below. The azo photoconductive pigment used in the charge generation layer is dispersed in a solution system of a suitable binder resin and a hydrazone charge transport material, and then coated on the charge transport layer prepared in advance to form the charge generation layer. Can be formed. Binders that can be used to form the charge generating layer by coating can be selected from a wide variety of insulating resins, as well as organic photoconductive polymers such as poly-N-vinylcarbazole, polyvinylanthracene, and polyvinylpyrene. can. Preferably, in addition to the photoconductive polymer, polyvinyl butyral, polyarylate (condensation polymer of bisphenol A and phthalic acid, etc.), polycarbonate, polyester, phenoxy resin, polyvinyl acetate, acrylic resin, polyacrylamide resin, polyamide, Examples include insulating resins such as urethane resin and epoxy resin. The resin contained in the charge generation layer is preferably 10 to
80% by weight, more preferably from the viewpoint of physical strength of the photoreceptor surface and carrier transportability within the charge generation layer.
The content is preferably 30 to 60% by weight. The proportion of the charge transporting material contained in the charge generation layer is preferably 10 to 70% by weight, and more preferably 20 to 60% by weight for the same reason as the amount of resin. The proportion of the azo photoconductive pigment contained in the charge generation layer is preferably 0.3 to 80% by weight. The solvent used in the paint for the charge generation layer is selected based on the resin used, the solubility of the charge transport material, and the dispersion stability of the charge generation material, but the solvent must be one that does not easily dissolve the charge transport layer and undercoat layer below. It is also necessary to select from Specific organic solvents include alcohols such as methanol, ethanol and isopropanol, ketones such as acetone, MEK and cyclohexanone, amides such as N,N-dimethylformamide and N,N-dimethylacetamide, and sulfoxides such as dimethylsulfoxide. 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; Aromatics such as benzene, toluene, xylene, ligroin, monochlorobenzene, dichlorobenzene, etc. can be used. Coating can be carried out using coating methods such as dip coating, spray coating, spinner coating, bead coating, Meyer bar coating, blade coating, roller coating, and curtain coating. For drying, it is preferable to dry to the touch at room temperature and then heat dry. Heat drying can be carried out at a temperature of 30 to 200° C. for a period of time ranging from 5 minutes to 2 hours, either stationary or under ventilation. The charge transport layer is electrically connected to the charge generation layer described above, receives charge carriers injected from the charge generation layer in the presence of an electric field, and transfers these charge carriers to the surface of the conductive support or the conductive layer. It has the function of being able to transport to the surface of the undercoat layer interposed between the charge transport layer and the charge transport layer. For the charge transport layer, a hole transporting charge transport material is used. Examples of hole-transporting substances include pyrene, N-ethylcarbazole, N-isopropylcarbazole,
Hydrazones including the hydrazone explained in the section of hydrazone used in the charge generation layer, 2,5-bis(P
-diethylaminophenyl)-1,3,4-oxadiazole, 1-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-methoxy-pyridyl(2)]-3-(P-diethylaminostyryl)-5-(P-diethylaminophenyl)pyrazoline, 1-[pyridyl(3)]-3
-(P-diethylaminostyryl)-5-(P-diethylaminophenyl)pyrazoline, 1-[Lepidyl(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,
1-phenyl-3-(P-diethylaminostyryl)-4-methyl(P-diethylaminophenyl)
Pyrazolines such as pyrazoline, 1-phenyl-3-(2-benzyl-P-diethylaminostyryl)-5-(P-diethylaminophenyl)pyrazoline, and spiroprazoline, 2-(P-diethylaminostyryl)-6-diethylaminobenzoxazole , 2-(P-diethylaminophenyl)-
4-(P-dimethylaminophenyl)-5-(2-
Oxazole compounds such as chlorophenyl)oxazole, 2-(P-diethylaminostyryl)-
Thiazole compounds such as 6-diethylaminobenzothiazole, bis(4-diethylamino-2-
Triarylmethane compounds such as methylphenyl)-phenylmethane, 1,1-bis(4-N,N
polyarylalkane such as -diethylamino-2-methylphenyl)heptane, 1,1,2,2tetrakis(4-N,N-dimethylamino-2-methylphenyl)ethane, triphenylamine,
Poly-N-vinylcarbazole, polyvinylpyrene, polyvinylanthracene, polyvinylacridine, poly-9-vinylphenylanthracene,
Examples include 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. Moreover, these charge transport substances may be one or two types.
More than one species can be used in combination. When the charge transport material does not have film-forming properties,
A film can be formed by selecting an appropriate binder. Resins that can be used as binders are:
For example, insulating resins such as acrylic resin, polyarylate, polyester, polycarbonate, polystyrene, acrylonitrile-styrene copolymer, acrylonitrile-butadiene copolymer, polyvinyl butyral, polyvinyl formal, polysulfone, polyacrylamide, polyamide, chlorinated rubber, or poly-N- Mention may be made of organic photoconductive polymers such as vinylcarbazole, polyvinylanthracene, polyvinylpyrene. Since the charge transport layer has a limit in its ability to transport charge carriers, it cannot be made thicker than necessary. Generally, it is 5-30μ, but the preferred range is 8-20μ. 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. As the substrate having the conductive layer, materials that are themselves conductive can be used, such as aluminum, aluminum alloy, copper, zinc, stainless steel, vanadium, molybdenum, chromium, titanium, nickel, indium, gold, and platinum. In addition, plastics (such as polyethylene, polypropylene, polyvinyl chloride, polyethylene terephthalate, acrylic, resin, polyethylene fluoride, etc.), conductive particles (e.g. carbon black,
A substrate made of plastic coated with silver particles (silver particles, etc.) together with a suitable binder, a substrate made of plastic or paper impregnated with conductive particles, a plastic containing a conductive polymer, etc. can be used. A subbing layer having barrier and adhesive functions can also be provided between the conductive layer and the charge transport layer. The undercoat layer may be made of 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. It can be formed by The appropriate thickness of the undercoat layer is 0.1 to 5 microns, preferably 0.5 to 3 microns. The electrophotographic photoreceptor used in the present invention is subject to deterioration due to ultraviolet rays, ozone, etc., dirt due to oil, etc., scratches due to metal chips, etc., damage to the photoreceptor due to photoreceptor contact members such as developing members, transfer members, cleaning members, etc. A protective layer or an insulating layer may be provided on the charge generation layer for the purpose of preventing scratching. In order to form an electrostatic latent image on this layer, the surface resistivity must be
It is desirable that it is 10 ¹¹ Ω or more. The protective layer used in the present invention is made of polyvinyl butyral, polyester, polycarbonate, acrylic resin, methacrylic resin, nylon, polyimide,
It can be formed by dissolving a resin such as polyarylate, polyurethane, styrene-butadiene copolymer, styrene-acrylic acid copolymer, styrene-acrylonitrile copolymer, etc. in a suitable organic solvent and coating the photosensitive layer on the photosensitive layer and drying it. Additionally, additives such as ultraviolet absorbers can be added to the resin liquid. At this time, the thickness of the protective layer is generally 0.05 to 20μ,
Particularly preferred is a range of 0.2 to 5μ. The layer structure of the electrophotographic photoreceptor of the present invention is as shown in the drawings. When using a photoreceptor in which a conductive layer, a charge transport layer, and a charge generation layer are laminated in this order, the charge transport material consists of a hole transport material, so it is necessary to positively charge the surface of the charge generation layer, and when exposed to light after charging, In the exposed area, holes generated in the charge generation layer are injected into the charge transport layer. On the other hand, electrons generated by exposure reach the surface and neutralize the positive charges, resulting in attenuation of the surface potential and electrostatic contrast between the surface and the unexposed area. A visible image can be 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, plastic film, etc. and then developed and fixed. Alternatively, a method may be used in which the electrostatic latent image on the photoreceptor is transferred onto an insulating layer of transfer paper, then developed and fixed. The type of developer, the developing method, and the fixing method may be any known ones or known methods, and are not limited to specific ones. The electrophotographic photoreceptor of the present invention can be used not only for electrophotographic copying machines, but also for laser printers and CRTs.
It can also be widely used in electrophotographic applications such as printers. The present invention will be explained below based on examples. Examples 1 to 17 An ammonia aqueous solution of casein (11.2 g of casein, 1 g of 28% ammonia water, 222 ml of water) was applied onto an aluminum plate using a Mayer bar so that the film thickness after drying was 1.0 μm, and dried. Next, the hydrazone compound of Exemplified Compound No. 1
Dissolve 5 g of polymethyl methacrylate resin (number average molecular weight 100,000) in 70 ml of benzene, apply this onto the charge generation layer using a Mayer bar so that the dry film thickness is 12μ, and dry to form the charge transport layer. was formed. Next, 45 g of hydrazone compound of Exemplified Compound No. 2
and polymethyl methacrylate resin (number average molecular weight
100,000) 45g of chlorobenzene dissolved in 800ml of the following structural formula Add 10g of the disazo pigment shown in and use a sand mill.
Dispersed for 10 hours. This dispersion was applied onto the previously formed charge transport layer by a dipping method and dried to form a charge generation layer having a thickness of 5 μm, thereby producing the photoreceptor of Example 1. Apart from the photoreceptor of Example 1, hydrazone compounds used in the charge generation layer were used as Exemplary Compounds Nos. 2 to 13, 16,
Photoreceptors of Examples 2 to 17 were prepared in exactly the same manner as in Example 1 except that Samples 18, 20, and 21 were replaced. The electrophotographic photoreceptor thus prepared was statically charged with a corona charge of +5 KV using an electrostatic copying paper tester Model SP-428 manufactured by Kawaguchi Electric Co., Ltd., and after being held in a dark place for 1 second, the electrophotographic photoreceptor was charged with an illuminance of 5 ux. It was exposed to light and its charging characteristics were investigated. As for the charging characteristics, the surface potential (V ₀ ) and the exposure amount (E _1/2 ) required to attenuate the potential to 1/2 when dark decaying for 1 second were measured. The results are shown in Table 1.

[Table] As shown in the table, the photoreceptor of the present invention exhibited good charging properties and sensitivity during charging. Comparative Example 1 A photoreceptor was prepared in exactly the same manner as in Example 1 except that the hydrazone compound was not used in the charge generation layer of Example 1, and its characteristics were investigated. Surface potential: +530V E _1/2 18ux·sec Compared to the photoreceptor of the present invention, this has extremely low sensitivity and is completely impractical. Examples 18 to 28 A polyvinyl alcohol film having a thickness of 1.1 μm was formed on the aluminum surface of an aluminum vapor-deposited polyethylene terephthalate film by dip coating. Next, photoreceptors of Examples 18 to 28 were prepared in exactly the same manner as in Example 1, using the materials shown in Table 2 instead of the charge transport layer, charge generation material, and charge transport material used in the charge generation layer of Example 1. The potential was measured. Table 3 shows the results.
Shown below. Optical memory has been added as a potential measurement item. By exposing a photoreceptor to light before charging, the charging potential of a photoreceptor with a strong optical memory decreases significantly, causing an extreme decrease in image density in the pre-exposed area or development of white areas. As a method for evaluating optical memory, a pre-exposure of 600 ux3 minutes is given, and the difference in surface potential (△V ₀ ) lowered compared to when there was no pre-exposure is expressed.

【table】

【table】

【table】

【table】

【table】

【table】

[Table] Comparative Examples 2 to 5 Same as Examples 18, 23, 26, and 27 except that the charge transport material shown in Table 4 was used instead of the hydrazone compound in the charge generation layer of Examples 18, 23, 26, and 27. Comparative photoreceptors 2 to 5 were prepared in the same manner. The results of potential measurement are shown in Table 5.

【table】

[Table] When hydrazone in the charge generation layer is replaced with a charge transport material other than hydrazone, the sensitivity and photomemory are significantly worse than in the case of hydrazone. The combined system has proven to be highly effective. Example 29 Each layer was coated on an aluminum cylinder with a diameter of 60 mm using the dipping method using the same coating solution except that the binder resin used for the charge generation layer in Example 1 was replaced with polycarbonate resin (number average molecular weight 75,000). An electrophotographic photoreceptor was prepared by sequentially laminating layers. Using a charging PPC copying machine (prototype) manufactured by Canon Inc., the initial dark area potential was set to 700V and the initial bright area potential was set to 100V, and 10,000 copies were printed using a charging toner and the durability was achieved. The potential was measured after leaving it for one night. The drum of the test prototype is equipped with a charging corona charger, an exposure section, a developing section, a transfer corona charger, a blade cleaner, and a pre-exposure lamp. The result of potential measurement is

[Table] Sensitivity fluctuations due to image display durability were small, images were free from blurring or image defects due to ozone deterioration, and no discharge unevenness due to corona wire contamination was observed, and beautiful images were obtained even after 10,000 prints. Example 30 A methanol solution of olivinyl butyral resin (saponification degree 100%, butyralization degree 75% by weight, number average molecular weight 30,000) was applied by dipping onto a photoreceptor prepared in exactly the same manner as in Example 29, and dried. The film thickness after
A protective layer of 3μ was formed. Using this photoconductor and using the same equipment as in Example 29, a durability test of 20,000 images was carried out in exactly the same manner as in Example 29, and the images obtained were extremely beautiful, indicating that the photoconductor had excellent durability. Something has been proven.

[Brief explanation of the drawing]

1 to 4 show the layer structure of the electrophotographic photoreceptor of the present invention. Reference numeral 1 is an azo photoconductive pigment, 2 is a binder resin + hydrazone carrier transport material, 3 is a charge generation layer, 4 is a charge transport layer, 5 is a conductive support,
6 is an undercoat layer, and 7 is a protective layer or an insulating layer.

Claims (1)

[Scope of Claims] 1. At least a hole-transporting charge transport layer and a charge generation layer are sequentially laminated on a conductive support, and the charge generation layer contains an azo photoconductive pigment and a hydrazone charge transport material. A laminated electrophotographic photoreceptor characterized by: 2. The azo photoconductive pigment used in the charge generation layer is a pigment represented by the general formula A(-N=N-B) (), and the hydrazone charge transport material used in the charge generation layer is a pigment represented by the general formula A(-N=N-B) (). However, in the general formula (), A represents a divalent organic group or [Formula] in which the carbon atoms to which the azo group is bonded form a conjugated double bond system, and B represents a phenolic OH group. Indicates a coupler having 2 or 3, and in the general formula (), D is a phenyl group which may have a substituent other than the substituted amino group, or a phenyl group which may have a substituent other than the N substituent. The laminated electrophotographic photoreceptor according to claim 1, wherein the material represents a carbazolyl group, and R and R' represent an alkyl group, an aralkyl group which may have a substituent, or an aryl group. 3. The laminated electrophotographic photoreceptor according to claim 1 or 2, wherein a protective layer or an insulating layer having a surface resistivity of 10 ¹¹ Ω or more is provided in the charge generation layer.