JPH0546938B2 - - Google Patents

Description

[Detailed description of the invention]

TECHNICAL FIELD The present invention relates to an electrophotographic photoreceptor, and more particularly to an electrophotographic photoreceptor provided with a photosensitive layer containing a disazo pigment as a charge-generating substance that generates charge carriers upon irradiation with light. Conventional technology Conventionally, electrophotographic photoreceptors have been used that use inorganic photosensitive materials such as selenium, selenium alloys, cadmium sulfide, and zinc oxide. It is widely used because it has excellent overall characteristics such as attenuation and sensitivity. However, since selenium-based photoreceptors are manufactured by vacuum evaporation, it is difficult to control their properties, the manufacturing cost is high, they are difficult to process into a belt shape due to their lack of flexibility, and they are susceptible to heat and mechanical shock. This poses problems such as restrictions on handling due to the sensitive nature of these substances. In addition, 2,4,7-trinitro-9 is an organic photoreceptor that has excellent flexibility and is relatively easy to manufacture.
- Some products with a photosensitive layer made of a charge transfer complex of fluorenone and poly-N-vinylcarbazole are in practical use, but their sensitivity is low and they are unsuitable as photoconductors for high-speed copying machines. . In recent years, extensive research has been carried out to eliminate these drawbacks of photoreceptors, and among them, a functionally separated photoreceptor in which the generation of charge carriers and the transport of the generated charges are performed by separate substances has been attracting attention. ing. The functionally separated photoreceptor is a multilayer type having a photosensitive layer consisting of a charge generation layer containing a charge generation substance that generates charge carriers upon light irradiation, and a charge transport layer containing a charge transport substance that transports the generated charges. photoreceptors, and dispersion-type photoreceptors in which a charge-generating substance is dispersed in a charge-transporting medium containing a charge-transporting substance. , is attracting attention as a photoreceptor for copying on plain paper. Such photoreceptors include: (1) A laminated photoreceptor that uses a thin layer of perylene derivatives vacuum-deposited as a charge generation layer and an oxadiazole derivative as a charge transport layer (U.S. Patent No.
(Refer to Publication No. 3871882) (2) Using a thin layer formed by coating an organic amine solution of Chlordiane Blue as the charge generation layer,
A laminated type photoreceptor using a hydrazone compound in a charge transport layer (see Japanese Patent Publication No. 42380/1983) is known. However, it is true that conventional laminated photoreceptors of this type have many advantages, but also have various drawbacks. The photoreceptor using the perylene derivative and oxadiazole derivative shown in (1) has a charge generation layer formed by vacuum evaporation, which increases the manufacturing cost. The photoconductor using chlordiane blue and hydrazone compound shown in (2) requires the use of an organic amine (e.g. ethylenediamine), which is generally difficult to handle, as a coating solvent to form the charge generation layer, which makes it difficult to fabricate the photoconductor. There are many shortcomings. A photoreceptor that is easy to manufacture and has excellent sensitivity is a photoreceptor using a disazo pigment having a styrylstilbene skeleton as a charge generating substance (Japanese Patent Laid-Open No. 53
-133445) is known, and in addition to this,
Photoreceptor using a disazo pigment having a dibenzothiophene skeleton as a charge generating substance
21728), a photoreceptor using a disazo pigment having a carbazole skeleton as a charge generating substance (Japanese Unexamined Patent Publication No. 53-95033), a photoreceptor using a trisazo pigment having a triphenylamine skeleton (Japanese Unexamined Patent Publication No. 53-95033)
-132347), a photoreceptor using a disazo pigment having an oxadiazole skeleton (Japanese Patent Application Laid-open No. 1983-
12742), a photoreceptor using a disazo pigment having a distyrylcarbazole skeleton (Japanese Unexamined Patent Publication No. 12742),
14967), a photoreceptor using a disazo pigment having a bisstilbene skeleton (Japanese Patent Application Laid-open No. 54-17733), and a photoreceptor using a disazo pigment having a fluorenone skeleton (Japanese Patent Laid-Open No. 54-22834). It has been reported. However, it is true that these photoreceptors have advantages and disadvantages, and it has been desired to develop photoreceptors with even more excellent characteristics in order to meet various demands. Purpose An object of the present invention is to provide an electrophotographic photoreceptor that is easy to manufacture and has sufficient sensitivity. Structure The electrophotographic photoreceptor of the present invention has the general formula () on a conductive support. (In the formula, A represents a coupler residue.) It is characterized by having a photosensitive layer containing a disazo pigment represented by the following formula. Couplers of general formula () include, for example, compounds having a phenolic hydroxyl group such as phenols and naphthols, aromatic amino compounds having an amino group, aminonaphthols having an amino group and a phenolic hydroxyl group, aliphatic or A compound having an aromatic enolic ketone group (active methylene group) is used, and preferably the coupler residue A has the following general formula (), (),
(), (), (), (), (), (), (
),
These are represented by the general formulas (XI) and (XII). [In the above formulas (), (), () and (),
X, Y ₁ , Z, m and n each represent the following. X:

[Formula] or -NHSO ₂ -R ₃ (R ₁ and R ₂ represent hydrogen or substituted or unsubstituted alkyl, and R ₃ represents a substituted or unsubstituted alkyl group or a substituted or unsubstituted aryl group.) Y ₁ : Hydrogen, halogen, substituted or unsubstituted alkyl group, substituted or unsubstituted alkoxy group, carboxy group, sulfo group, substituted or unsubstituted sulfamoyl group, or

[Formula] (R ₄ is hydrogen, an alkyl group or a substituent thereof,
Represents a phenyl group or a substituted product thereof, and Y ₂ is a hydrocarbon ring group or a substituted product thereof, a heterocyclic group or a substituted product thereof, or

[Formula] (where R ₅ is a hydrocarbon ring group or its substituted product, a heterocyclic group or its substituted product, or a styryl group or its substituted product, R ₆ is hydrogen,
R 5 and R 6 may represent an alkyl group, a phenyl group or a substituent thereof, or R ₅ and R ₆ may form a ring together with the carbon atoms bonded to them. ) is shown. ) Z: a hydrocarbon ring or a substituent thereof, or a heterocycle or a substituent thereof n: an integer of 1 or 2 m: an integer of 1 or 2] [In formulas () and (), R ₇ represents a substituted or unsubstituted hydrocarbon group, and X is as defined above. ] [In the formula, R ₈ represents an alkyl group, a carbamoyl group, a carboxyl group or an ester thereof, and Ar ₁
represents a hydrocarbon ring group or a substituted product thereof, and X is the same as above. ] [In the above formulas () and (), R ₉ represents hydrogen or a substituted or unsubstituted hydrocarbon group,
Ar ₂ represents a hydrocarbon ring group or a substituted product thereof. ] Examples of the hydrocarbon ring of Z in the general formula (), (), () or () include a benzene ring and a naphthalene ring, and examples of the heterocycle include an indole ring, a carbazole ring, a benzofuran ring, a dibenzofuran ring, etc. can be exemplified. Furthermore, examples of substituents on the ring of Z include halogen atoms such as chlorine atoms and bromine atoms. As the hydrocarbon ring group in Y ₂ or R ₅ ,
Examples of the heterocyclic group include a phenyl group, a naphthyl group, an anthryl group, a pyrenyl group, and a pyridyl group, a thienyl group, a furyl group, an indolyl group, a benzofuranyl group, a carbazolyl group, a dibenzofuranyl group, and the like. Examples of the ring formed by combining R ₅ and R ₆ include a fluorene ring. Substituents on the hydrocarbon ring group or heterocyclic group of Y ₂ or R ₅ or the ring formed by R ₅ and R ₆ include alkyl groups such as methyl group, ethyl group, propyl group, butyl group, methoxy basis,
Alkoxy groups such as ethoxy, propoxy, and butoxy groups; halogen atoms such as chlorine and bromine; dialkylamino groups such as dimethylamino and diethylamino groups; diralkylamino groups such as dibenzylamino; and trifluoromethyl groups. Halomethyl group, nitro group, cyano group, carboxyl group or its ester, hydroxyl group, -SO ₃ Na
Examples include sulfonic acid groups such as. Examples of substituents for the phenyl group of R ₄ include halogen atoms such as chlorine atoms and bromine atoms. Typical examples of the hydrocarbon group in R ₇ or R ₉ include alkyl groups such as methyl, ethyl, propyl, and butyl, aralkyl groups such as benzyl, aryl groups such as phenyl, or substituents thereof. I can give an example. Substituents on the hydrocarbon group of R ₇ or R ₉ include alkyl groups such as methyl group, ethyl group, propyl group, butyl group, methoxy group, ethoxy group,
Alkoxy groups such as propoxy groups and butoxy groups,
Examples include halogen atoms such as chlorine atoms and bromine atoms, hydroxyl groups, and nitro groups. As the hydrocarbon ring group in Ar ₁ or Ar ₂ ,
Representative examples include phenyl group and naphthyl group, and substituents for these groups include:
Alkyl groups such as methyl group, ethyl group, propyl group, butyl group, alkoxy groups such as methoxy group, ethoxy group, propoxy group, butoxy group, halogen atoms such as nitro group, chlorine atom, bromine atom, cyano group, dimethylamino group and dialkylamino groups such as diethylamino groups. Furthermore, among X, a hydroxyl group is particularly suitable. Among the above coupler residues, those represented by the above general formulas (), (), (), (), () and () are preferred, and among these, those in which X in the general formula is a hydroxyl group are preferred. Also, among these, the general formula (′) (Y ₁ and Z are the same as above.) A coupler residue represented by the following is preferable, and more preferably a coupler residue represented by the general formula (Z, Y ₂ and R ₂ are the same as above.) It is a coupler residue represented by. Furthermore, among the above preferred coupler residues, general formula (XI) or () (Z, R ₂ , R ₅ and R ₈ are the same as above, and R ₁₀ can be exemplified by the substituent of Y ₂ above.) Those represented by the following are suitable. Specific examples of the disazo pigment used in the present invention as described above are shown in the following structural formula. For simplicity, only the structural formula of A, which is a coupler residue, is shown.

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[Table] By using the disazo pigment of the present invention as described above, an extremely sensitive electrophotographic photoreceptor can be easily manufactured.Among these, disazo pigments that are particularly preferred as charge generating substances are Nos. 1, 16, and 59. ,60,
62, 64, 71, 75. The disazo pigments of the present invention can be used, for example, by Richard
4,4'-diaminotriphenylamine prepared by the method described in Herz, Ber., 23 , 2538 is diazotized to a tetrazonium salt by a conventional method, and the tetrazonium salt and the corresponding coupler are combined in an appropriate manner. organic solvents, such as N,N-
It can be easily produced by coupling reaction with a base in dimethylformamide. As an example, the production example of disazo pigment No. 1 is shown below, but other disazo pigments can also be easily produced according to this production example, except for changing the coupler. Production example 4,4-
After adding 5.51g of diaminotriphenylamine and stirring at room temperature for 1 hour, it was cooled to -2°C, and then 3.31g of sodium nitrite was added to this and 12.ml of water.
was added dropwise over a period of 30 minutes at a temperature of -2 to 1°C. Thereafter, after stirring at the same temperature for 1 hour and 30 minutes, a trace amount of insoluble portion was removed, and 20 ml of 42% borofluoric acid was added to the reaction solution, and the mixture was allowed to cool and stand still. The produced red-orange needle-like crystals were separated, washed with ethanol, and then dried to obtain 8.55 gr (yield: 90.3%) of tetrazonium difluoroborate. In the infrared absorption spectrum (KBr tablet method), an absorption band based on N ₂ was observed at 2230 cm ^-1 . Tetrazonium salt thus obtained 0.95
gr and 1.26 gr of 2-hydroxy-3-naphthoic acid anilide as a coupling component were dissolved in 230 ml of cooled N,N-dimethylformamide,
A solution consisting of 0.66 g of sodium acetate and 10 ml of water was added dropwise to this at a temperature of 17 to 21°C over 5 minutes. Thereafter, the mixture was further stirred at room temperature for 3 hours.
Then, the formed precipitate was collected, washed five times with 300 ml of N,N-dimethylformamide, and then washed with 300 ml of water.
After washing twice with
(yield 67.4%). Melting point 300℃ or higher

[Table] Also, infrared absorption spectrum (KBr tablet method)
is shown in Figure 1. In the electrophotographic photoreceptor of the present invention, a disazo pigment is used as a charge generating substance in the photosensitive layer, and a typical structure of this photoreceptor is shown in FIGS. 2 and 3. The photoreceptor shown in FIG. 2 has a laminated photosensitive layer 19 on a conductive support 11, which is composed of a charge generation layer 15 mainly composed of a disazo pigment 13 and a charge transport layer 17 mainly composed of a charge transport substance. It is something that In the photoreceptor shown in FIG. 2, the imagewise exposed light passes through the charge transport layer and reaches the charge generation layer 15, where the disazo pigment 13 generates a charge, while the charge transport layer 17 The mechanism is such that the disazo pigment 13 generates the charge necessary for light attenuation, and the charge transport layer 17 transports the charge. The photoreceptor shown in FIG. 3 has a photosensitive layer 19 mainly composed of a disazo pigment 13, a charge transporting substance, and an insulating binder on a conductive support 11.
Again, the disazo pigment 13 is a charge generating substance. In addition, it is also possible to reverse the charge generation layer and charge transport layer shown in FIG. 2 in the photoreceptor. The thickness of the photosensitive layer is as shown in FIG.
The thickness of 5 is preferably 0.01 to 5μ, more preferably
It is 0.05~2μ. If the thickness is less than 0.01μ, charge generation will not be sufficient, and if it is more than 5μ, the residual potential will be too high for practical use. Charge transport layer 1
The thickness of 7 is preferably 3 to 50μ, more preferably 5 to 30μ. If the thickness is less than 3μ, the amount of charge will be insufficient, and if it is more than 50μ, the residual potential will be too high to be practical. The charge generation layer 15 is mainly composed of a disazo pigment represented by the above general formula, and may further contain a binder, a plasticizer, and the like.
Further, the proportion of the disazo pigment in the charge generation layer is preferably 30% by weight or more, more preferably 50% by weight.
That's all. The charge transport layer 17 is mainly composed of a charge transport substance and a binder, and may further contain a plasticizer. The proportion of charge transport material in the charge transport layer is from 10 to 95% by weight, preferably from 30 to 90% by weight. If the proportion of the charge transport substance is less than 10% by weight, almost no charge transport occurs;
If it exceeds 95% by weight, the mechanical strength of the photoreceptor film will be so poor that it cannot be put to practical use. In the case of the photoreceptor shown in FIG. 3, the photosensitive layer 19'
The thickness is preferably 3 to 50μ, more preferably 5 to 30μ. The proportion of the disazo pigment in the photosensitive layer 19' is preferably 50% by weight or less, more preferably 20% by weight or less, and the proportion of the charge transport material is preferably 10 to 95% by weight, more preferably 30 to 95% by weight. It is 90% by weight. The gist of the present invention is to use a specific disazo pigment represented by the above general formula as a charge generating substance in an electrophotographic photoreceptor, and to use other components such as a conductive support and a charge transporting substance. Any of the conventionally known ones can be used, and these will be specifically explained below. The conductive support used in the photoreceptor of the present invention includes a metal plate made of aluminum, copper, zinc, etc., a plastic sheet made of polyester, etc., or a plastic film on which a copper conductive material such as aluminum or SnO ₂ is vapor-deposited, or Conductive treated paper or the like is used. As a binder, polyamide, polyurethane,
polyester, epoxy resin, phenoxy resin,
Condensation resins such as polyketone and polycarbonate, polyvinyl ketone, polystyrene, poly-N-
Examples include vinyl polymers such as vinyl carbazole and polyacrylamide, but any insulating and adhesive resin can be used. Examples of the plasticizer include halogenated paraffin, polychlorinated biphenyl, dimethylnaphthalene, and dibutyl phthalate. In addition, silicone oil or the like may be added to improve the surface properties of the photoreceptor. Charge transport materials include hole transport materials and electron transport materials. Examples of the hole transport substance include compounds represented by the following general formulas (1) to (11). (1) [In the formula, R ₁ represents a methyl group, ethyl group, 2-hydroxyethyl group, or 2-chloroethyl group, R ₂ represents a methyl group, ethyl group, benzyl group, or phenyl group, and R ₃ represents hydrogen, chlorine, Bromine, alkyl group having 1 to 4 carbon atoms, 1 to 4 carbon atoms
represents an alkoxy group, dialkylamino group or nitro group. ] (2) [In the formula, Ar is a naphthalene ring, anthracene ring,
It represents a styryl group or a substituted product thereof, or a pyridine ring, a furan ring, or a thiophene ring, and R represents an alkyl group or a benzyl group. ] (3) [In the formula, R ₁ represents an alkyl group, a benzyl group, a phenyl group, and R ₂ represents hydrogen, an alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, a dialkylamino group, a dialkylamino group, or It represents a diarylamino group, n represents an integer of 1 to 4, and when n is 2 or more, R ₂ may be the same or different. R ₃ represents hydrogen or a methoxy group. 〕 (Four) [In the formula, R ₁ represents an alkyl group having 1 to 11 carbon atoms, a substituted or unsubstituted phenyl group, or a heterocyclic group, and R ₂ and R ₃ may be the same or different, and hydrogen, ~4 alkyl groups,
It represents a hydroxyalkyl group, a chloroalkyl group, a substituted or unsubstituted aralkyl group, and
R ₂ R ₃ may be bonded to each other to form a nitrogen-containing heterocycle. R ₄ may be the same or different and represents hydrogen, an alkyl group having 1 to 4 carbon atoms, an alkoxy group, or a halogen. 〕 (Five) [In the formula, R represents hydrogen or a halogen atom, and Ar represents a substituted or unsubstituted phenyl group, naphthyl group, anthryl group, or carbazolyl group. ] (6) [In the formula, R ₁ represents hydrogen, halogen, cyano group, alkoxy group having 1 to 4 carbon atoms, or alkyl group having 1 to 4 carbon atoms, and Ar is

[expression] or

[Formula], R ₂ represents an alkyl group having 1 to 4 carbon atoms, and R ₃ represents hydrogen, halogen, an alkyl group having 1 to 4 carbon atoms, or an alkyl group having 1 to 4 carbon atoms.
4 represents an alkoxy group or a dialkylamino group, n is 1 or 2, and when n is 2, R ₃ may be the same or different, and R ₄ and
R ₃ represents hydrogen, a substituted or unsubstituted alkyl group having 1 to 4 carbon atoms, or a substituted or unsubstituted benzyl group. 〕 (7) [In the formula, R is a carbazolyl group, pyridyl group, thienyl group, indolyl group, furyl group, or a substituted or unsubstituted phenyl group, styryl group, naphthyl group, or anthryl group, and these substituents are dialkylamino groups , an alkyl group, an alkoxy group, a carboxy group or an ester thereof, a halogen atom, a cyano group, an aralkylamino group, an N-alkyl-N-aralkyl amino group, an amino group, a nitro group, and an acetylamino group. represents. 〕 (8) [In the formula, R ₁ represents a lower alkyl group or a benzyl group, and R ₂ represents a hydrogen atom, a lower alkyl group,
lower alkoxy group, halogen atom, nitro group,
It represents an amino group or an amino group substituted with a lower alkyl group or a benzyl group, and n represents an integer of 1 or 2. ] (9) [In the formula, R ₁ represents a hydrogen atom, an alkyl group, an alkoxy group, or a halogen atom, R ₂ and R ₃ represent an alkyl group, a substituted or unsubstituted aralkyl group, or a substituted or unsubstituted aryl group, and R ₄ represents a hydrogen atom or a substituted or unsubstituted phenyl group, and Ar represents a phenyl group or a naphthyl group. 〕 (Ten) [In the formula, n is an integer of 0 or 1, R ₁ is a hydrogen atom, an alkyl group, or a substituted or unsubstituted phenyl group, and A is

【formula】

[Formula] represents a 9-anthryl group or a substituted or unsubstituted N-alkylcarbazolyl group, where
R ₂ is a hydrogen atom, an alkyl group, an alkoxy group, a halogen atom, or -NR ₃ R ₄ (However, R ₃ and
R ₄ represents an alkyl group, a substituted or unsubstituted aralkyl group, a substituted or unsubstituted aryl group, R ₃ and R ₄ may form a ring), and m is 0, 1, 2 or 3. is an integer, and when m is 2 or more, R ₂ may be the same or different. ] (11) [In the formula, R ₁ , R ₂ and R ₃ represent hydrogen, a lower alkyl group, a lower alkoxy group, a dialkylamino group or a halogen atom, and n is 0 or 1
represents. ] The compound represented by general formula (1) includes, for example, 9
-Ethylcarbazole-3-aldehyde 2-methyl-1-phenylhydrazone, 9-ethylcarbazole-3-aldehyde 1-benzyl-1-phenylhydrazone, 9-ethylcarbazole-3
-Aldehyde 1,1-diphenylhydrazone and the like. Compounds represented by general formula (2) include, for example, 4-diethylaminostyrene-β-aldehyde, 1-methyl-1-phenylhydrazone, 4-diethylaminostyrene-β-aldehyde, 1-methyl-1-phenylhydrazone,
Examples include methoxynaphthalene-1-aldehyde and 1-benzyl-1-phenylhydrazone. Examples of the compound represented by general formula (3) include 4-methoxybenzaldehyde 1-methyl-1-phenylhydrazone, 2,4-dimethoxybenzaldehyde 1-benzyl-1-phenylhydrazone,
4-diethylaminozenzaldehyde 1,1-
Diphenylhydrazone, 4-methoxybenzuraldehyde 1-penzyl-1-(4-methoxy)
Examples include phenylhydrazone, 4-diphenylaminobenzaldehyde 1-benzyl-1-phenylhydrazone, and 4-dibenzylaminobenzaldehyde 1,1-diphenylhydrazone. The compound represented by the general formula (4) includes, for example, 1,1-
Bis(4-dibenzylaminophenyl)propane, tris(4-diethylaminophenyl)methane, 1,1-bis(4-dibenzylaminophenyl)propane, 2,2'-dimethyl-4,4'- Examples include bis(diethylamino)-triphenylmethane. Examples of the compound represented by the general formula (5) include 9-(4-diethylaminostyryl)anthracene and 9-bromo-10-(4-diethylaminostyryl)anthracene. Examples of the compound represented by the general formula (6) include 9-(4-dimethylaminobenzylidene)fluorene and 3-(9-fluorenylidene)-9-ethylcarbazole. Examples of the compound represented by the general formula (7) include 1,2-bis(4-diethylaminostyryl)benzene and 1,2-bis(2,4-dimethoxystyryl)benzene. Examples of the compound represented by the general formula (8) include 3-styryl-9-ethylcarbazole, 3-(4-methoxystyryl)
-9-ethylcarbazole and the like. General formula (9)
Compounds represented by include, for example, 4-diphenylaminostilbene, 4-dibenzylaminostilbene, 4-ditolylaminostilbene, 1-
(4-diphenylaminostyryl)naphthalene,
Examples include 1-(4-diethylaminostyryl)naphthalene. The compound represented by general formula (10) includes:
Examples include 4'-diphenylamino-α-phenylstilbene and 4'-methylphenylamino-α-phenylstilbene. Examples of the compound represented by the general formula (11) include 1-phenyl-3-(4
-diethylaminostyryl)-5-(4-diethylaminophenyl)pyrazoline, 1-phenyl-3
-(4-dimethylaminostyryl)-5-(4-dimethylaminophenyl)pyrazoline and the like. Other hole transport substances include, for example, 2,
5-bis(4-diethylaminophenyl)-1,
3,4-oxadiazole, 2,5-bis[4-
(4-diethylaminostyryl)phenyl]-1,
Oxadiazole compounds such as 3,4-oxadiazole, 2-(9-ethylcarbazolyl-3-)-5-(4-diethylaminophenyl)-1,3,4-oxadiazole, 2- Vinyl-4-(2
There are low molecular weight compounds such as oxazole compounds such as -chlorophenyl)-5-(4-diethylaminophenyl)oxazole and 2-(4-diethylaminophenyl)-4-phenyloxazole.
Further, polymer compounds such as poly-N-vinylcarbazole, halogenated poly-N-vinylcarbazole, polyvinylpyrene, polyvinylanthracene, pyrene formaldehyde resin, and ethylcarbazole formaldehyde resin can also be used. Examples of electron transport substances include chloranil, bromoanil, tetracyanoethylene, tetracyanoquinone dimethane, 2,4,7-trinitro-9-fluorenone, 2,4,5,7-tetranitro-9-fluorenone, 2, 4,5,7-tetranitroxanthone, 2,4,8-trinitrothioxanthone, 2,6,8-trinitro-4H
-indeno[1,2-b]thiophene-4one,
1,3,7-trinitrodibenzothiophene-
Examples include 5,5-dioxide. These charge transport substances may be used alone or in combination of two or more. In any of the photoreceptors obtained as described above, an adhesive layer or a barrier layer may be provided between the conductive support and the photosensitive layer, if necessary. Suitable materials for these layers include polyamide, nitrocellulose, and aluminum oxide.
Further, the film thickness is preferably 1 μm or less. To make the photoreceptor shown in Figure 2, disazo pigments USP 3973959, USP 3996049 are deposited on a conductive support.
Alternatively, fine particles of a disazo pigment are dispersed in a suitable solvent in which a binder is dissolved if necessary, and this is coated on a conductive support and dried. If necessary, the surface is finished by buffing as shown in JP-A-51-90827, or after adjusting the film thickness, a solution containing a charge transport substance and a binder is applied and dried. It can be obtained by In order to produce the photoreceptor shown in FIG. 3, fine powder of a disazo pigment is dispersed in a solution containing a charge reversing material and a binder, and this is applied onto a conductive support and dried. In either case, the disazo pigment used in the present invention is used after being ground to a particle size of 5 μm or less, preferably 2 μm or less, using a ball mill or the like.
Application may be carried out by conventional means, such as a doctor blade, dipping, wire bar, etc. To perform copying using the photoreceptor of the present invention, the surface of the photosensitive layer is charged and exposed, and then developed.
If necessary, this can be achieved by transferring to paper or the like. Effects As is clear from the above explanation and the Examples and Comparative Examples described later, the electrophotographic photoreceptor of the present invention uses a disazo pigment having a triphenylamine skeleton as a charge-generating substance, and is therefore superior to conventional photoreceptors. It has excellent properties such as being easier to manufacture than photoreceptors, being highly sensitive, and having stable characteristics even when the photoreceptor is used repeatedly. EXAMPLES Next, the present invention will be specifically explained using Examples, but the embodiments of the present invention are not limited thereby. Example 1 76 parts by weight of disazo pigment No. 75, 1260 parts by weight of a tetrahydrofuran solution (solid content concentration 2%) of polyester resin (Vylon 200 manufactured by Toyobo Co., Ltd.), and 3700 parts by weight of tetrahydrofuran were pulverized and mixed in a ball mill. The obtained dispersion was applied using a doctor blade onto the aluminum surface of a polyester base (conductive support) on which aluminum was deposited, and air-dried to form a charge generation layer with a thickness of about 1 μm. On this charge generation layer, 9-
Ethylcarbazole-3-aldehyde 1-methyl-1 phenylhydrazone 2 parts by weight, polycarbonate resin (Panlite K-1300: manufactured by Teijin Ltd.) 2
A solution prepared by mixing and dissolving parts by weight and 16 parts by weight of tetrahydrofuran was applied using a doctor blade, and dried at 80°C for 2 minutes and then at 105°C for 5 minutes to form a charge transport layer with a thickness of about 18 μm. A laminated type photoreceptor No. 1 shown in FIG. 2 was prepared. Examples 2 to 5 Photoreceptors Nos. 2 to 5 were prepared in the same manner as in Example 1, except that disazo pigments shown in Table 1 below were used in place of disazo pigment No. 75 used in Example 1. Examples 6 to 10 1-phenyl-3-(4-
Photoreceptors Nos. 6 to 10 were prepared in the same manner as in Example 1, except that pyrazoline (diethylaminostyryl)-5-(4-diethylaminophenyl) and the disazo pigment shown in Table 1 below were used. Examples 11 to 15 Photoreceptors Nos. 11 to 15 were prepared in the same manner as in Example 1, except that 9-(4-diethylaminostyryl)anthracene was used as the charge transport substance and the disazo pigment shown in Table 1 below was used. did. Examples 16-20 4′-diphenylamino-α as charge transport substance
- Photoreceptors Nos. 16 to 20 were prepared in the same manner as in Example 1, except that phenylstilbene was used and the disazo pigment shown in Table 2 below was used. These photoconductors No. 1 to 20 were negatively charged by performing -6KV corona discharge for 20 seconds using an electrostatic copying paper tester (manufactured by Kawaguchi Electric Seisakusho Co., Ltd., SP428 type). , leave it in a dark place for 20 seconds, measure the surface potential Vpo (V) at that time, and then irradiate the surface with light using a tungsten lamp at an illuminance of 4.5 lux until the surface potential becomes 1/1 of Vpo. 2
Find the time (seconds) until the exposure amount E1/2
(lux/second) was calculated. Table 1 shows the results.
- Shown in Table-2.

【table】

[Table] Furthermore, photoreceptors No. 4 and No. 7 of the present invention were installed in a copying machine model Ricopy P-500 manufactured by Ricoh Co., Ltd., and image production was repeated 10,000 times. As a result, clear images were obtained without any of the photoreceptors changing due to repeated copying processes. From this, it can be understood that the photoreceptor of the present invention is also excellent in durability.

[Brief explanation of the drawing]

FIG. 1 shows an infrared absorption spectrum (KBr tablet method) of disazo pigment No. 1 used in the present invention. FIGS. 2 and 3 are enlarged sectional views showing examples of the structure of the photoreceptor of the present invention. 11... Conductive support, 13... Disazo pigment, 15... Charge generation layer, 17... Charge transport layer,
19,19'...Photosensitive layer.

Claims (1)

[Claims] 1 General formula () on a conductive support (In the formula, A represents a coupler residue.) An electrophotographic photoreceptor comprising a photosensitive layer containing a disazo pigment represented by the following formula.