JPH01186962A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To improve sensitivity and durability by incorporating a specific diazo pigment into a photoconductive layer. CONSTITUTION:The diazo pigment expressed by the formula I is incorporated into the photoconductive layer. In the formula, R1, R2 denote an alkyl group, arom. hydrocarbon group, arom. heterocyclic group; these groups may have a substituent; R1, R2 may be the same or different; A1, A2 denote a residual coupler group having a phenolic hydroxyl group; A1, A2 may be the same or different. The practicable high-sensitivity characteristic and the stable potential characteristic in repetitive use are thereby obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] 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 a photoconductive layer.

[Prior Art] Pigments and dyes exhibiting photoconductivity have been published in numerous publications.

For example, RCA Revlew'Vo1.23, P,
413-P, 419 (1962, 9), there was a presentation on the photoconductivity of phthalocyanine pigments, and electrophotographic photoreceptors using this phthalocyanine pigment were disclosed in U.S. Pat. No. 3,397,086 and U.S. Pat. No. 381 fl.
It is described in the specification of No. 118. In addition, examples of organic semiconductors used in electrophotographic photoreceptors include US Pat. No. 4,315,983 and US Pat. No. 4,32716.
9 specification and Re5each Discl.

5ure” 20517 (1981, 5), methine squaric acid dyes described in U.S. Pat. No. 3,824,099, U.S. Pat. No. 3,898,084, and U.S. Pat. No. 4,251.
Examples include disazo pigments described in the specification of No. 613 and the like.

Such organic semiconductors are easier to synthesize than inorganic semiconductors and can be synthesized as compounds that have photoconductivity for light in the required wavelength range. Electrophotographic photoreceptors formed on conductive substrates have the advantage of improved color sensitivity, but only a few of them are practical in terms of sensitivity and durability.

[Problems to be Solved by the Invention] The purpose of the present invention is to provide a novel photoconductive material that can be used in all current electrophotographic processes, has practical high sensitivity characteristics, and is stable during repeated use. An object of the present invention is to provide an electrophotographic photoreceptor having excellent potential characteristics.

[Means for Solving the Problems, Effects] The present invention is an electrophotographic photoreceptor having a photoconductive layer on a conductive substrate, characterized in that the photoconductive layer contains a disazo pigment represented by the following general formula (1). It consists of an electrophotographic photoreceptor.

In the general formula, R1 and R2 represent an alkyl group, an aromatic hydrocarbon group, or an aromatic heterocyclic group, and the above groups may have a substituent, and R, and R2 may be the same or different. It's okay,
A1 and A2 represent coupler residues having a phenolic hydroxyl group, and A1 and A2 may be the same or different.

Specifically, R and R2 are alkyl groups such as methyl, ethyl, propyl, isopropyl, and butyl, and aromatic hydrocarbon groups such as phenyl,
Groups such as naphthyl and benzyl, aromatic heterocyclic groups include, for example, groups such as pyridyl and quinolyl, and substituents for the above groups include, for example, halogen atoms such as fluorine atom, chlorine atom, and bromine atom, methyl, Alkyl groups such as ethyl, propyl, isopropyl, butyl, methoxy,
Examples include alkoxy groups such as ethoxy, propoxy, and phenoxy, and substituted amino groups such as nitro group, cyano group, dimethylamino, dibenzylamino, diphenylamino, morpholino, and piperidino.

More preferable specific examples of coupler residues having a phenolic hydroxyl group represented by A1 and A2 include the following general formula (
Examples include residues shown in 2) to (6).

In the general formula, X is fused with a benzene ring to form a polycyclic ring such as a naphthalene ring, anthracene ring, carbazole ring, benzcarbazole ring, dibenzcarbazole ring, dibenzofuran ring, dibenzonaphthofuran ring, diphenylene sulfide ring, or fluorenone ring. Indicates the residues necessary to form an aromatic ring or a heterocycle.

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

R3 and R4 represent a hydrogen atom, an alkyl group, an aryl group, an aralkyl group, or a heterocyclic group, and the above groups may have a substituent, or R3 and R4 together with the nitrogen atom to which they are bonded represent a cyclic ami7 group.

Specifically, alkyl groups include methyl, ethyl, propyl, and butyl, aralkyl groups include benzyl, phenethyl, and naphthylmethyl, and aryl groups include phenyl, diphenyl, naphthyl, and anthryl, and hetero Examples of the ring group include groups such as carbazole, dibenzofuran, benzimidacylon, benzthiazole, thiazole, and pyridine.

General formula Rt In the formula, R'5 represents a hydrogen atom, an alkyl group, an aryl group, or an aralkyl group, and the above group may have a substituent. Specifically, R5 is the same as R3 and R4 above. Illustrated by example.

The alkyl group, aryl group, aralkyl group, and heterocyclic group represented by the substituents R3 to R5 in general formulas (2) and (3) may further include other substituents such as fluorine atom, chlorine atom, iodine atom, Halogen atoms such as bromine atoms, methyl, ethyl,
Substituted with alkyl groups such as propyl, isopropyl, butyl, alkoxy groups such as methoxy, ethoxy, propoxy, phenoxy, nitro group, cyano group, dimethylamino, dibenzylamino 1, substituted amine groups such as diphenylamino, morpholino, piperidino, pyrrolidino, etc. may have been done.

General formula 5. Yl, where Y represents a divalent group of an aromatic hydrocarbon or a divalent group of a heterocycle containing a nitrogen atom, and examples of the divalent group of an aromatic hydrocarbon include 0-phenylene. divalent group of monocyclic aromatic hydrocarbon, O-naphthylene, perinaphthylene,
Examples include divalent groups of aromatic hydrocarbons such as 1.2-antrylene and 9.10-phenanthrylene, and examples of divalent groups of heterocyclic rings containing a nitrogen atom in the ring include 3.4 Divalent groups such as -pitezoldiyl group, 2.3-pyridinediyl group, 4,5-pyrimidinediyl group, 6.7-indazoldiyl group, and 6.7-chiralindiyl group are mentioned.

In the general formula, R6 represents an aryl group or a heterocyclic group, and the above group may have a substituent. Specifically, the aryl group is phenyl, naphthyl, anthryl, pyrenyl, and the heterocyclic group is pyridyl. , thienyl, furyl, carbazolyl group.

Further, as substituents for aryl groups and heterocyclic groups, halogen atoms such as fluorine atom, chlorine atom, iodine atom, and bromine atom, alkyl groups such as methyl, ethyl, propyl, isopropyl, butyl, methoxy, ethoxy, propoxy,
Alkoxy groups such as phenoxy, nitro groups, cyano groups,
Examples include substituted amine groups such as dimethylamino, dibenzylamino, diphenylamino, morpholino, piperidino, and pyrrolidino.

X has the same meaning as X in the general formula (2).

"' , propyl, butyl, aralkyl groups include benzyl, phenethyl, naphthylmethyl, heptalyl groups include phenyl, diphenyl, naphthyl, anthryl, heterocyclic groups include carbazolyl, thienyl, pyridyl, furyl, etc. Substituents include halogen atoms such as fluorine, chlorine, iodine, and bromine; alkyl groups such as methyl, ethyl, propyl, isopropyl, and butyl; alkoxy groups such as methoxy, ethoxy, propoxy, and phenoxy; , cyano group, dimethylamino, dibenzylamino, diphenylamino, morpholino, piperidino, pyrrolidino and other substituted amino groups.

X has the same meaning as X in the general formula (2).

Typical specific examples of the disazo pigment represented by the general formula (1) of the present invention are listed below.

Exemplary pigments have different parts R1,
A specific structure will be expressed by describing only R2, A, , A2.

Basic type Exemplary pigment (1) R1, R2 knee @ Exemplary pigment (2) R1, R2 knee @ Exemplary pigment (3) R1IR2 knee.

Exemplary Pigment (4) R,, R2-■ Exemplary Pigment (5) R1: So R2 Kyu H1 Exemplary Pigment (6) R1: -@, R2: -C)! 3 Exemplary Pigments (7) R1: -CH Exemplary Pigments (8) Fl, , R2: ■◇ A1. A2: C, HrH Exemplary Pigment (9) R,, R2: Be◇ Exemplary Pigment (10) H Exemplary Pigment (11) A1. A2: CH) CH Exemplary Pigment (12) Exemplary Pigment (13) M Exemplary Pigment (14) Exemplary Pigment (15) R1, or R2: +CM3 Exemplary Pigment (16) Exemplary Pigment (17) Exemplary Pigment (18) Exemplary Pigment ( 19) R,, R2: Exemplary Pigment (20) Exemplary Pigment (21) R,, R2: B◇ Exemplary Pigment (22) Exemplary Pigment (23) Exemplary Pigment (24) R,, R2 Exemplary Pigment (25) ) R1, R2 Knee @ Exemplary Pigment (26) n,, R2 Knee @ Exemplary Pigment (27) R1, R2 Knee @ Exemplary Pigment (2B) R1, R2 Knee.

Exemplary pigment (29) R,, R2 knee @ Exemplary pigment (30) Exemplary pigment (31) r! ga Exemplary pigment (32) Exemplary pigment (33) Exemplary pigment (34) R1, R2: @ Exemplary pigment (35) Exemplary pigment (36) R1: (■　　　R2:　(filter FULLER.

Exemplary Pigment (37) R1: Be◇ R2: Jade) OC Engineering H5 Exemplary Pigment (
38) R1: Mo R2: Exemplary Pigment (39) Exemplary Pigment (40) R1 @ R2': -@-CF3H The disazo pigments shown in the above specific examples do not limit the scope of the claims of the present invention. .

These disazo pigments are 18! Alternatively, two or more types can be used in combination.

These disazo pigments are produced by treating, for example, a diamine with the following structural formula with nitrite using a conventional method to form a tetrazonium, and then -All(2) to (6).
) is coupled with a coupler having a coupler residue having a phenolic hydroxyl group in the presence of an alkali, or the tetrazonium salt of the diamine is coupled with BF.
Once isolated in the form of 4-salt, PF6-salt or zinc chloride double salt, it is coupled with a coupler in the presence of an alkali in a suitable solvent such as N,N-dimethylformamide or dimethylsulfoxide. It can be easily synthesized by

Synthesis Example (Synthesis of Exemplary Pigment (1)) 500 m of bee mold - 180 m of water, 37.4 m of concentrated hydrochloric acid
Q (0.44% mol) and mol) were added and stirred while cooling in an ice water bath to bring the temperature to 3°C.Next, 9.5g (0°14 mol) of sodium nitrite was dissolved in 15mM of water. The liquid was added dropwise over 25 minutes while controlling the liquid temperature to be in the range of 0 to 5°C (7)K, and after the addition was completed, the mixture was stirred at the same temperature for an additional 30 minutes. Carbon was added to the reaction solution, and the mixture was filtered to obtain a tetrazotized solution.

Next, put 1.5 grams of water into a 3-liter beaker, dissolve 47.3 g (1.18 moles) of sodium hydroxide, and then dissolve 3 grams of naphthol As (3-hydroxy-2-naphthoic acid anilide).
6.3 g (0,138 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-mentioned tetrazotization solution was added dropwise with stirring over 30 minutes, then stirred for 2 hours, and then incubated overnight. After washing the liquid with water, the solid content was 60.2g.
The obtained water paste was then stirred and filtered four times at room temperature using 900 ml of N,N-dimethylformamide. Thereafter, stirring was repeated twice with 900 mJl of MEK, followed by drying under reduced pressure to produce 9.8 g of purified pigment a (yield: 83.
5%).

Melting point〉300℃ Elemental analysis Calculated value (%) Experimental value (%) C7B,
13 76.21 H4,634,8O N 12.25 12.30 Typical pigment synthesis methods have been described above.

Other disazo pigments represented by general formula (1) are also synthesized in the same manner.

Coatings with the aforementioned disazo pigments exhibit photoconductivity and can therefore be used in photoconductive layers of subsequent electrophotographic photoreceptors.

That is, in the specific example of the present invention, an electrophotographic photoreceptor is formed by forming a film of the above-mentioned disazo pigment on a conductive substrate by a vacuum evaporation method, or by dispersing it in a suitable binder and forming a film. can be created.

In a preferred embodiment of the present invention, the photoconductive layer of the electrophotographic photoreceptor is functionally separated into a charge generation layer and a charge transport layer as a charge generation layer in an electrophotographic photoreceptor.

Photoconductive coatings as described above can be applied.

The charge generation layer contains as much of the above-mentioned photoconductive disazo pigment as possible in order to obtain sufficient absorbance, and the generated charge carriers reach the interface with the charge transport layer or the interface with the conductive support. For efficient transport, a thin film layer, for example a thin film layer with a thickness of 5 IL or less, preferably 0.0 l-1p, is preferred.

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 by dispersing the disazo pigment in a suitable binder and coating it on a conductive substrate, or can be obtained by forming a deposited film using a vacuum 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 (condensation polymer of bisphenol A and phthalic acid, etc.), polycarbonate, polyester, phenoxy resin, polyvinyl acetate, acrylic resin, polyacrylamide, polyamide, polyvinylpyridine, cellulose resin, polyurethane, epoxy resin , casein, polyvinyl alcohol,
Examples include insulating resins such as polyvinylpyrrolidone.

1! Contained f in the formation layer! 1 m nl11 is 8
A content of 0% by weight or less, preferably 40% by weight or less is suitable.

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, N-dimethylformamide, N, N-
Amides such as dimethylacetamide, sulfoxides such as dimethyl sulfoxide, ethers such as tetrahydrofuran, dioxane, ethylene glycol methyl ether, esters such as methyl acetate, ethyl acetate, chloroform, methylene chloride, dichloroethylene,
Carbon tetrachloride, aliphatic halogenated hydrocarbons such as trichlorethylene, benzene, toluene, xylene,
Aromatic hydrocarbons such as ligroin, monochlorobenzene, dichlorobenzene, etc. can be used.

Coating methods include dip coating, spray coating, spinner coating, bead coating, Meyer bar coating, blade coating,
This can be carried out using a coating method such as a roller coating method or a curtain call 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 laminated on or under the charge generation layer.

When a charge transport layer is formed on a charge generation layer, the substance that transports charge carriers in the charge transport layer (hereinafter referred to as charge transport material) is substantially in the wavelength range of electromagnetic waves to which the charge generation layer is sensitive. The electromagnetic waves referred to herein, which are preferably insensitive, include gamma rays, X-rays, ultraviolet rays, visible light,
Near infrared.

Includes a broad definition of light that includes infrared rays, far infrared rays, etc.

When the photosensitive wavelength range of the charge transport layer coincides with or overlaps that of the charge generation layer, charge carriers generated in both layers trap each other, resulting in a decrease in sensitivity.

Charge transporting substances include electron transporting substances and hole transporting substances, and electron transporting substances include chloranil, tetracyanoethylene, tetracyanoquinodimethane, 2,4,
5.7-tetranitro-9-fluorenone, 2,4,5
．． Examples include electron-withdrawing substances such as 7-tetranitroxanthone and 2,4.8-4-linitrothioxanthone, and polymerized versions of these electron-withdrawing substances.

Examples of hole-transporting substances include pyrene, N-ethylcarbazole, N-methyl-N-phenylhydrazino-3-methylidene-9-ethylcarbazole, and N,N-diphenylhydrazi/-3-methylidene-10-dityl. Phenothiazine, p-diethylaminobenzaldehyde-N, N-diphenylhydrazone, p-pyrrolidinobenzaldehyde-N.

Hydrazones such as 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, 1-phenyl-3-(
p-diethylaminostyryl)-4-methyl-5-(p
-diethylaminophenyl)pyrazoline, spiropyrazoline and other pyrazolines, 2-(p-diethylaminostyryl)-6-dinithylaminobenzoxazole, 2
Oxazole compounds such as -(p-diethylaminostyryl)-4-(p-dimethylaminophenyl)-5-(2-chlorophenyl)oxazole, 2-(p-diethylaminostyryl)-6-dinithylaminobenzothiazole, etc. thiazole compounds, triarylmethane compounds such as bis(4-diethylamino-2-methylphenyl)-phenylmethane, 1,1-bis(4-N
, N-diethylamino-2-methylphenyl)hebutane, polyarylalkane such as 1,1,2,2-tetrakis(4-N,N-dimethylamino-2-methylphenyl)ethane, triphenylamine, poly -N-vinylcarbazole, polyvinylpyrene, polyvinylanthracene, polyvinylacridine, poly-9-vinylphenylanthracene, pyrene-formaldehyF m fat,
Examples include ethylcarbazole-formaldehyde resin.

In addition to these organic charge transport materials, inorganic materials such as selenium, selenium-tellurium, amorphous silicon, and cadmium Ta oxide 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 formal, polysulfone, polyacrylamide, polyamide, chlorinated rubber, and organic photoconductive polymers such as poly-N-vinylcarbazole polyvinylanthracene and polyvinylpyrene.

The charge transport layer has a limit to its ability to transport charge carriers, so it cannot be made thicker than necessary. Generally, the thickness is 5 to 30 mm, but the preferred range is 8 to 20 mm. When forming the charge transport layer by coating, an appropriate coating method as described above can be used.

A photoconductive layer having such a laminated structure of a charge generation layer and a charge transport layer is provided on a conductive substrate. As the conductive substrate, materials whose substrates themselves are 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 tetra L/7 tallate) have a layer formed by vacuum deposition of aluminum, aluminum alloy, indium oxide, tin oxide, indium oxide-tin oxide alloy, etc. , acrylic resin, polyfluoride etching), conductive substrates in which conductive particles (e.g. carbon black, silver particles, etc.) are coated on plastic with a suitable binder, conductive substrates in which conductive particles are impregnated into plastic or paper. A conductive substrate or a plastic that accommodates a conductive polymer can be used.

A subbing layer having a barrier function and an adhesive function can also be provided between the conductive substrate 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 thickness of the undercoat layer is 0.1 to 5 μl, preferably 0.1 to 5 μl.
5 to 3 ends is appropriate.

When using a photoreceptor in which a conductive substrate, a charge transport layer, and a charge generation layer are laminated in this order, and the charge transport substance is an electron transport substance, the surface of the charge generation layer must be negatively charged, and after charging, Upon exposure, electrons generated in the charge generation layer in the exposed portion are injected into the charge transport layer, and then reach the substrate.

On the other hand, holes generated in the charge generation layer reach the surface, attenuation of the surface potential occurs, and electrostatic contrast occurs between the charge generation layer and the unexposed area.

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

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

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

On the other hand, when the charge generation layer is made of a hole transporting substance, the surface of the charge generation layer must be positively charged.

After stripping m, when exposed to light, the genuine tag generated in the charge generation layer is injected into the charge transport layer in the exposure area, and then reaches the substrate. On the other hand, the charge generation layer generates an odor.

The electrons reach one surface, and the surface potential attenuates, creating an electrostatic contrast between the surface and the unexposed area. During development, it is necessary to use a negatively charged toner, contrary to when an electron transporting substance is used.

In addition, as another specific example of the present invention, the above-mentioned general formula (1
Examples include electrophotographic photoreceptors in which a disazo pigment shown in ) is contained in the same layer as a charge transport substance. At this time, a charge transfer complex compound consisting of poly-N-vinylcarbazole and trinitrofluorenone can be used in addition to the above-mentioned charge transport substance.

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

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

If necessary, two or more types of disazo pigments represented by the general formula (1) may be combined for the purpose of increasing the sensitivity of the photoreceptor by using a combination of pigments with different light absorption, or obtaining a panchromatic photoreceptor. Alternatively, it can also be used in 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〕

Examples 1 to 15 Ammonia aqueous solution of casein (casein 1
1.2 g of aqueous ammonia, 1 g of ammonia water, 222 ml of water) was applied using a Meyer bar so that the film thickness after drying was 1.0 island, and dried.

Next, 5 g of Exemplary Pigment (1) was added to a solution of 2 g of butyral resin (degree of butyralization: 63 mol %) dissolved in 95 ml of ethanol, and dispersed in a sand mill for 2 hours. This dispersion was applied to the previously formed caseia layer so that the film thickness after drying was 0.
．． It was coated with a Mayer bar to a thickness of 5#L and dried to form a charge generation layer.

5g of hydrazone compound and polymethyl methacrylate (
Dissolve 5 g of number average molecule (fk 100,000) in 70 m of benzene, apply this onto the charge generation layer using a Mayer bar so that the film thickness after drying is t2 g, and dry to form a charge transport layer. An electrophotographic photoreceptor of Example 1 was prepared.

Examples 2 to 1 using other exemplary pigments in place of exemplary pigment (1)
An electrophotographic photoreceptor corresponding to No. 5 was prepared in exactly the same manner.

The electrophotographic photoreceptor thus prepared was tested using an electrostatic copying paper tester (Model EPA-8100, Kawaguchi Electric AV).
4) using a static method to corona charge at 15 KV, hold in a dark place for 1 second, and then expose to light at an illuminance of 2 lux to examine charging characteristics.

4? P? As for the lt characteristics, the surface potential (We) and the exposure fi (E 1/2) required to attenuate the potential to 172 when dark decayed for 1 second were measured. Show the results.

/ v-V El/2 1uxsec1
(1) 570 4.52 (2)
610 2.23 (3) 6
00 3.14 (7) 590 4
．． 25 (10) 610 3.66
(15) 600 4.07 (16)
800 2.78 (18) 5
60 3.59 (21) 590 5
．． 310 (24) 820 3.711
(28) 600 3.112 (
29) 600 2゜513 (31)
590”2.214 (3B)
600 4.915 (37) 590
3.3 From the above results, it can be seen that all the electrophotographic photoreceptors of the present invention have sufficient charging ability and sufficient sensitivity.

Examples 16 to 20 Using the electrophotographic photoreceptors prepared in Examples 1, 2, 4, 6, and 10, fluctuations in bright area potential and dark area potential were measured when the electrophotographic photoreceptors were used in reverse.

The photoreceptor was attached to the cylinder of an electrophotographic copying machine equipped with a -5.6 KV corona charger, an exposure optical system, a developer, a transfer charger, a static elimination exposure optical system, and a cleaner. This copying machine is configured to produce an image on transfer paper as the cylinder is driven.

Using this copying machine, the initial bright area potential (vL) and dark area potential (Vo) were set to -100V, respectively.

-eoov, and the bright area potential (VL) and dark area potential (Vo) were measured after using it 5,000 times. Show the results.

20 to 570
130 Example 21 On the charge generation layer formed in Example 1, 5 g of 2.4.7-dolinitro-9-fluorenone and poly-4,4'-dioxydiphenyl-2,2-propane carbonate (molecular weight 300,000 A coating solution prepared by dissolving 5 g of ) in 70 ml of tetrahydrofuran was applied so that the coating amount after drying was 10 g 7 m 2 and dried.

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

VO: +610V El/2: 4.3Jlux, sec Example 22 A polyvinyl alcohol film with a film thickness of 0.5 was formed on the aluminum surface of an aluminum 11M polyethylene terephthalate film.Next, the voice disazo pigment used in Example 1 was used. The dispersion was applied onto the previously formed polyvinyl alcohol layer using a Mayer bar so that the film thickness after drying was 0.5 mm, and dried to form a charge generating layer.

Next, 5 g of a pyrazoline compound with the structural formula and 5 g of polyarylate (condensation polymer of bisphenol A and terephthalic acid-isophthalic acid)
A solution prepared by dissolving 100 mL of tetrahydrofuran in 70 mJL of tetrahydrofuran was applied onto the charge generation layer so that the film thickness after drying would be lO, and 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 Examples 1 and 16. Show the results.

VQ knee 590V El/2: 4.2nux, sec Durability characteristics Initial vD knee 800V VL knee 100V After 5,000 sheets vo knee 590V VL knee 100V From the above results, the sensitivity is good and the potential stability during long-term use. In good condition.

Example 23 An ammonia aqueous solution of casein (described above) was applied to an aluminum plate having a thickness of 100 mm and dried to form a subbing layer having a thickness of 015 mm.

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 mL of tetrahydrofuran. This charge transfer complex compound and Ig of exemplified pigment (3) were added to a solution in which 5 g of polyester (trade name: Byron, Toyobo IlJ) was dissolved in 70 mM of tetrahydrofuran, and dispersed. This dispersion was applied onto the subbing layer and dried to form 12 layers to prepare an electrophotographic photoreceptor. Example 1 shows the electrophotographic characteristics of this electrophotographic photoreceptor.
Measured using the same method as above. However, the electrical charge was set to 10.

Show the results.

Vo: +600V El/2: 2.91ux, see [Effects of the Invention] The electrophotographic photoreceptor of the present invention contains a specific disazo pigment in the photoconductive layer, so that the inside of the photoconductive layer containing the disazo pigment It is estimated that either one or both of carrier generation efficiency and carrier transport efficiency is improved, and the electrophotographic photoreceptor has high sensitivity and excellent potential stability during long-term use.g.

Claims (1)

[Scope of Claims] 1. An electrophotographic photoreceptor having a photoconductive layer on a conductive substrate, characterized in that the photoconductive layer contains a disazo pigment represented by the following general formula (1). . General formula ▲ Numerical formula, chemical formula, table, etc. ▼ (1) In the formula, R_1 and R_2 represent an alkyl group, an aromatic hydrocarbon group, or an aromatic heterocyclic group, and the above groups may have a substituent. , R_1 and R_2 may be the same or different, A_1 and A_2 represent coupler residues having a phenolic hydroxyl group, and A_1 and A_2 may be the same or different. 2. The electrophotographic photoreceptor according to claim 1, wherein one or both of A_1 and A_2 in general formula (1) is a coupler residue having a phenolic hydroxyl group represented by the following general formula (2). General formula▲There are mathematical formulas, chemical formulas, tables, etc.▼(2) In the formula, group, an aryl group, an aralkyl group, a heterocyclic group, and the above group may have a substituent, or R
_3 and R_4 represent a cyclic amino group together with the nitrogen atom to which they are bonded. 3. The electrophotographic photoreceptor according to claim 1, wherein one or both of A_1 and A_2 in general formula (1) is a coupler residue having a phenolic hydroxyl group represented by the following general formula (3). General formula ▲ Numerical formula, chemical formula, table, etc. ▼ (3) In the formula, R_5 represents an alkyl group, an aryl group, or an aralkyl group, and the above group may have a substituent. 4. The electrophotographic photoreceptor according to claim 1, wherein one or both of A_1 and A2 in the general formula (1) is a coupler residue having a phenolic hydroxyl group represented by the following general formula (4). General formula ▲ Numerical formula, chemical formula, table, etc. ▼ (4) In the formula, Y represents a divalent aromatic hydrocarbon group or a heterocyclic divalent group containing a nitrogen atom in the ring. 5. The electrophotographic photoreceptor according to claim 1, wherein one or both of A_1 and A_2 in general formula (1) is a coupler residue having a phenolic hydroxyl group represented by the following general formula (5). General formula ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (5) In the formula, and the above group may have a substituent. 6. The electrophotographic photoreceptor according to claim 1, wherein one or both of A_1 and A_2 in general formula (1) is a coupler residue having a phenolic hydroxyl group represented by the following general formula (6). General formula ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (6) In the formula, group, an aralkyl group, or a heterocyclic group, and the above group may have a substituent.