JP2506372B2 - Electrophotographic photoreceptor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (A) Field of Industrial Application The present invention relates to an electrophotographic photoreceptor, and more particularly to a novel electrophotographic photoreceptor having a photosensitive layer containing an azo pigment.

More specifically, it relates to a highly durable electrophotographic photosensitive member which has high sensitivity and is suitable for repeated use.

(B) Conventional Technology and its Problems Conventionally, as electrophotographic photoreceptors, selenium, zinc oxide,
Those having a photosensitive layer containing an inorganic photoconductor such as cadmium sulfide as a main component have been widely known.

However, these are not always satisfactory in sensitivity, thermal stability, moisture resistance, durability, etc., and in particular,
Selenium and cadmium sulfide are toxic and therefore
There were also restrictions on handling.

On the other hand, the electrophotographic photoreceptor having a photosensitive layer containing an organic photoconductive compound as a main component is relatively easy to manufacture.
Further, it generally has many advantages as compared with selenium photoconductors, such as being superior in thermal stability, and has received much attention in recent years.

As such an organic photoconductive compound, poly-N
-Vinylcarbazole is well known and this and 2,4,
An electrophotographic photoreceptor having a photosensitive layer containing a charge transfer complex formed from a Lewis acid such as 7-trinitro-9-fluorenone as a main component is not always satisfactory in sensitivity and durability.

On the other hand, the laminated or dispersed function-separated type photoconductor in which the carrier generation function and the carrier movement function are shared by separate substances, the selection range of each material is wide, and charging characteristics, sensitivity, durability It has an advantage that an electrophotographic photosensitive member having arbitrary electrophotographic characteristics can be prepared relatively easily.

Conventionally, various substances have been proposed as carrier-generating substances or carrier-moving substances.

For example, an electrophotographic photoreceptor having a photosensitive layer in which a carrier generating layer made of amorphous selenium and a carrier moving layer containing poly-N-vinylcarbazole as a main component are combined has been put into practical use.

However, the carrier generating layer made of amorphous selenium has a drawback that it has poor durability.

Further, various proposals have been made to use organic dyes and pigments as carrier generating substances. For example, as an electrophotographic photoreceptor containing a monoazo pigment or a bisazo pigment in a photosensitive layer, Japanese Patent Publication No. Sho 48-30513, JP-A No. 52-4241, JP-A-54-46558, JP-B-56-11945 and the like are already known.

However, these azo pigments are not always satisfactory in characteristics such as sensitivity, residual potential or stability when repeatedly used, and the selection range of carrier transfer substances is also limited. The reality is that nothing that satisfies a wide range of requirements has yet to be obtained.

(C) Object of the Invention An object of the present invention is to provide an electrophotographic photoreceptor containing an azo pigment which is stable to heat and light and has an excellent carrier-generating ability.

Another object of the present invention is to provide an electrophotographic photosensitive member which has high sensitivity and a small residual potential, and whose durability does not change even after repeated use, and which has excellent durability.

Still another object of the present invention is to provide an electrophotographic photoreceptor containing an azo pigment which can effectively act as a carrier generating substance even in combination with a wide range of carrier transferring substances.

(D) Structure of the Invention The inventors of the present invention have found that the azo pigment represented by the following general formula [I] can act as an active ingredient of a photoconductor as a result of earnest research to achieve the above object. Is completed.

(In the formula, A represents hydrogen, an alkyl group which may have a substituent, an aryl group which may have a substituent, a heterocyclic residue, a carboxylic acid and its ester, cyano, X represents hydrogen,
Cyano, halogen, lower alkyl, phenyl, m
Is an integer of 1 or 2, n is an integer of 0 or 1, and Cp is a coupler residue. ) Cp represents a residue of a coupler that reacts with a diazo group, and a coupler residue having a structure represented by the following general formula [II] is particularly effective.

(Where Y is condensed with a benzene ring to form a polycyclic aromatic ring such as naphthalene or anthracene ring, or condensed with a benzene ring to form a heterocyclic ring such as a carbazole ring, a benzocarbazole ring or a dibenzyldifuran ring. R ₁ is an optionally substituted alkyl group (eg, methyl group, ethyl group, n-propyl group, iso-propyl group, n
-Butyl group, sec-butyl group, amyl group, 1-octyl group, benzyl group, p-chlorobenzyl group, 3,4 dichlorobenzyl group, p-methylbenzyl group, 2-phenylethyl group, α-naphthylmethyl group Group, β-naphthylmethyl group)
Aryl group (for example, phenyl group, tolyl group, xylyl group, biphenyl group, chlorophenyl group, dichlorophenyl group, bromphenyl group, methoxyphenyl group, ethoxyphenyl group, butoxyphenyl group, phenoxyphenyl group, nitrophenyl group, cyanophenyl group, Hydroxyphenyl group, carboxyphenyl group, N, N-dimethylaminophenyl group, α, α, α-tolufluoromethylphenyl group, methylthiophenyl group, α-naphthyl group, β-
Naphthyl group), R ₂ is a heterocyclic group with R ₁ , (for example, thiazolyl group, 5-nitrothiazolyl group, carbazolyl group, indolyl group, pyrrolyl group, acridyl group, benzo (b) thiophenyl, benzoinimidazolyl group, oxazolyl group). Group, chlorooxazolyl group, triazolyl group, piperidyl group, pyridyl group, kyrinor group). R ₃ is O, S, −NH
Represents-, R ₄ and R ₅ are hydrogen, an optionally substituted alkyl group, a nitro group, a methoxy group, an ethoxy group, an acetyl group,
A cyano group and halogen are shown.

Z is a chain hydrocarbon necessary for forming a 5-membered ring or a 6-membered ring. That is, in the present invention, by using the azo pigment represented by the general formula [I] as a photoconductive substance constituting the photosensitive layer of an electrophotographic photoreceptor, an excellent carrier for the azo pigment of the present invention can be obtained. Utilizing only the generating ability, and by using this as a carrier generating substance of a so-called function-separated electrophotographic photoreceptor in which carrier generation and migration are performed by separate substances, excellent film physical properties, charge retention, sensitivity, An electrophotographic photosensitive material that has excellent electrophotographic characteristics such as residual potential, has little fatigue deterioration even after repeated use, and does not change the above characteristics due to heat or light, and can exhibit stable characteristics. You can create a body.

Specific examples of the azo pigment represented by the general formula [I] useful in the present invention include those having the following structural formulas:
However, the azo pigment of the present invention is not limited thereto.

Exemplified azo pigment The azo pigment represented by the general formula [I] has the general formula The divalent amino compound represented by the formula (1) is azotized by a conventional method, and then the corresponding coupler is coupled in the presence of an alkali, or the above-mentioned diazonium salt of the divalent amino compound is fluorinated or zinc chloride double salt. Etc., once isolated, and then subjected to a coupling reaction with a coupler in the presence of an organic or inorganic alkali in a suitable solvent (for example, N, N-dimethylformamide, dimethylsulfoxide, ethanol, dioxane). Therefore, it can be easily synthesized.

Next, a synthesis method of a typical example of the azo pigment used in the present invention will be shown.

Synthesis Example 1 (Exemplified Azo Pigment No. 23) p-nitroacetophenone and p-nitrophenylhydrazine were heated to reflux in equimolar ethanol to give p-nitroacetophenone- (p-nitrophenylhydrazone) (melting point 294 to 296 ° C). ) Get. The hydrazone thus obtained is used with phosphorus oxychloride and dimethylformamide to obtain a pyrazole compound represented by the following structural formula.

Pyrazole aldehyde thus obtained, p
-Nitrobenzylcyanamide is dissolved in dioxane and reacted with piperidine to obtain 1- (p-nitrophenyl) -3- (p-nitrophenyl) -4- (β-cyano-nitrostyryl) -pyrazole. Pyridine was used as the recrystallization solvent.

The trinitro compound thus obtained is reduced with iron powder and glacial acetic acid to obtain a reddish brown triamino compound represented by the following structural formula.

 As the recrystallization solvent, n-propyl alcohol was used.

0.73 g of the triamino compound thus obtained was added with 30 ml of 2N-hydrochloric acid.
A solution prepared by dissolving 0.8 g of sodium nitrite in a minimum amount of water was added dropwise under ice cooling, and the mixture was reacted for about 1 hour. Next, activated carbon was added, the mixture was filtered, and further washed with a small amount of water to prepare a diazonium salt solution.

This diazonium salt aqueous solution was treated with 2-hydroxy-N- (3,5-α, α, α, α ′,
2.5 'of α', α'-hexafluoroxylyl) -3-naphthoic acid amide and 6 g of triethanolamine were added to a solution of 100 ml of dimethylformamide at room temperature, and the black-purple precipitate immediately formed was filtered. After washing with acetone,
After thorough washing with dimethylformamide, then washing with hot water and finally with acetone, and drying at 80 ° C. for about 5 hours, 1.9 g of a black powder having a slightly metallic luster was obtained.

 The melting point was 350 ° C or higher.

Synthesis Example 2 (Exemplified Azo Pigment No. 24) 1,3-di (p-nitrophenyl) 4-obtained in Synthesis Example 1
Formyl-pyrazole is reacted with p-chlorobenzyl cyanamide to give 1,3-di (p-nitrophenyl) -4.
-(Β-Cyanochlorostyryl) pyrazole is obtained. Synthesis Example 1 except that 2-hydroxy-N- (4-chlorophenyl) -3-naphthoic acid amide was used as the coupler
Then, reduction and diazotization are carried out in substantially the same manner to obtain the desired bisazo pigment. The decomposition point was 338 ° C.

Other azo pigments of the present invention can also be obtained according to the above-mentioned synthesis examples.

The electrophotographic photoreceptor of the present invention has a photosensitive layer containing one kind or two or more kinds of the azo pigments represented by the general formula [I]. Although various types of photosensitive layers are known, the photosensitive layer of the electrophotographic photoreceptor of the present invention may be any of them. Usually, it is a photosensitive layer of the type illustrated below.

Photosensitive layer composed of azo pigment Photosensitive layer in which azo pigment is dispersed in binder Photosensitive layer in which azo pigment is dispersed in well-known charge transfer material The above-mentioned photosensitive layers are charge generation layers, and well-known charge transfer material A photosensitive layer in which a charge transfer layer containing is laminated. When the azo pigment represented by the general formula absorbs light, it generates a charge carrier with extremely high efficiency. The generated carrier can move using an azo pigment as a medium, but it is preferable to move a known charge transfer substance as a medium. From this point, the photosensitive layer of the form and is particularly preferable.

Charge transfer substances are generally classified into two types, electron transfer substances and hole transfer substances. Both can be used in the photosensitive layer of the photoreceptor of the present invention, and a mixture of those having the same type of function or Mixtures of those having different functions can also be used. The substance having electron transfer is an electron-withdrawing compound having an electron-withdrawing group such as a nitro group, a cyano group and an ester group, and as these substances, for example, 2,4,
Nitrated fluorenones such as 7-trinitrofluorenone, 2,4,5,7-tetranitrofluorenone, or tetracyanoquinodimethane, tetracyanoethylene, 2,4,5,7
Examples thereof include compounds such as tetranitroxanthone and 2,4,8-trinitrothioxanthone, and compounds obtained by polymerizing these electron absorbing compounds.

Further, as the hole transfer medium, examples of electron donating organic photoconductive compounds include the following.

Aromatic amine compounds Hydrazone compounds Heterocyclic compound And so on. Other polymer compounds include poly-N-vinylcarbazole and halogenated poly-
N-vinylcarbazole, polyvinylpyrene, polyvinylanthracene, polyvinylacridine, polyglycidylcarbazole, polyvinylacenaphthylene, ethylcarbazole: formaldehyde resin, and the like can also be used.

The carrier transfer substance is not limited to those described here, and when used, one or two or more carrier transfer substances may be mixed and used.

The electrophotographic photoreceptor of the present invention can be manufactured by a conventional method.

For example, for an electrophotographic photoreceptor having a photosensitive layer of the type described above, a coating solution obtained by dissolving or dispersing the azo pigment represented by the general formula [I] in a suitable medium is coated on a conductive support. , Dried, usually several dozen μm to several dozen μm
It can be manufactured by forming a photosensitive layer having a film thickness of.

As a medium for preparing the coating solution, a basic solvent that dissolves an azo pigment such as n-butylamine or ethylenediamine, or an ether such as tetrahydrofuran or 1,4-dioxane: methyl ethyl ketone, a ketone such as cyclohexanone: toluene, xylene, etc. Aromatic hydrocarbons: N, N−
Aprotic polar solvents such as dimethylformamide, acetonitrile, N-methylpyrrolidone and dimethylsulfoxide: alcohols such as methanol, ethanol and isopropanol: esters such as ethyl acetate, methyl acetate, methyl cellosolve acetate: chlorine such as dichloroethane and chloroform A medium in which an azo pigment such as a modified hydrocarbon is dispersed may be used.

When a medium in which the azo pigment is dispersed is used, it is necessary to make the azo pigment into fine particles having a particle size of 5 μm or less, preferably 3 μm or less, and most preferably 1 μm or less.

Further, as the conductive support on which the photosensitive layer is formed, any of those known in electrophotographic photoreceptors can be used.

Specific examples thereof include metal drums such as aluminum and copper, sheets, laminates of these metal foils, and vapor-deposited materials.

Further, there may be mentioned plastic films, plastic drums, papers, etc. which have been subjected to a conductive treatment by coating a conductive substance such as metal powder, carbon black, copper iodide, or a polymer electrolyte with a suitable binder.

In addition, examples include conductive plastic sheets and drums containing conductive materials such as metal powder, carbon black, and carbon fibers.

By dissolving the binder in the coating liquid used for forming the photosensitive layer of the above type, an electrophotographic photoreceptor having the photosensitive layer of the above type can be produced.

In this case, the medium of the coating liquid preferably dissolves the binder.

Examples of the binder include polymers and copolymers of vinyl compounds such as styrene, vinyl acetate, acrylic acid ester, and methacrylic acid ester, phenoxy resin, polysulfone, arylate resin, polycarbonate, polyester, cellulose ester, cellulose ether, butyral resin, epoxy resin. Examples include various polymers such as resins and acrylic polyol resins.

The amount of binder used is usually 0.1 to 5 relative to the azo pigment.
It is in the range of weight times.

When forming a photosensitive layer of this type, an azo pigment is used in a binder, for example, with a particle size of 3 μm.
It is preferable that the particles are present in the form of fine particles of m or less, especially 1 μm or less.

Similarly, if the charge transfer medium is dissolved in the coating liquid used for forming the photosensitive layer of the above type, the electrophotographic photoreceptor having the photosensitive layer of the above type can be manufactured.

As the charge transfer medium, any of those exemplified above can be used.

Aside from the charge transfer medium such as polyvinyl carbazole and polyglycidyl carbazole which can be used as a binder itself, it is preferable to use a binder for other substances.

As the binder, any of those exemplified above can be used.

In this case, the amount of binder used is usually
It is in the range of 0.5 to 100 times by weight, and the amount of the charge medium used is usually 0.2 to 3.0 times by weight, preferably
It is in the range of 0.3 to 1.2 times the weight. In the case of a charge transfer medium which itself can be used as a binder, it is usually used in an amount of 1 to 10 times by weight with respect to the azo pigment.

This type of photosensitive layer is the same as the type of photosensitive layer described above.
It is preferable that the azo pigment is present in the charge transfer medium and the binder in the form of fine particles.

An electrophotographic photosensitive material having a photosensitive layer of any of the above types can be formed by applying a coating solution obtained by dissolving a charge transfer medium in an appropriate medium onto the photosensitive layers of the above types (1) to (4) to form a charge transfer layer. The body can be manufactured.

In this case, the photosensitive layers of the above types 1 to 4 serve as a charge generation layer. The charge transfer layer does not necessarily have to be provided on the charge generation layer, and may be provided between the charge generation layer and the conductive support.

 However, the former is preferable in terms of durability.

The charge transfer layer is formed in the same manner as the above-mentioned photosensitive layer. That is, a coating solution obtained by removing the azo pigment from the coating solution for forming the photosensitive layer may be used as the coating solution.

 The charge transfer layer is usually 5 to 50 μm thick.

Of course, the photosensitive layer of the electrophotographic photoreceptor of the present invention may contain a known sensitizer.

Suitable sensitizers include Lewis acids and dye dyes that form charge transfer complexes with organic photoconductive materials.

Examples of the Lewis acid include chloranil, 2,3-dichloro-1,4-naphthoquinone, 2-methylanthraquinone,
1-nitroanthraquinone, 1-chloro-5-nitroanthraquinone, 2-chloroanthraquinone, quinones such as phenatrenequinone, aldehydes such as 4-nitrobenzaldehyde, 9-benzoylanthracene, indandione, 3,5-dinitro Benzophenone, 3,3 ′,
Ketones such as 5,5-tetranitrobenzophenone, phthalic anhydride, acid anhydrides such as 4-chloronaphthalic anhydride,
Tetracyanoethylene, terephthalmalondinitr,
Cyano compounds such as 4-nitrobenzalmalon nitrile: 3
Examples thereof include electron-withdrawing compounds such as benzalphthalide, 3- (α-cyano-p-nitrobenzal) phthalide, and 3- (α-cyano-p-chlorobenzal) phthalide.

Examples of dyes include triphenylmethane dyes such as methyl violet, brilliant green, and crystal violet, thiazine dyes such as methylene blue, naphthoquinone dyes such as hydrochrome green G, cyanine dyes, pyrylium salts, thiapyrylium salts, and benzopyrylium salts. Is mentioned.

In addition to these, inorganic photoconductive fine particles such as selenium and selenium-arsenic alloy, and organic photoconductive pigments such as copper-phthalocyanine pigment and perylene pigment may be contained.

Further, the photosensitive layer of the electrophotographic photoreceptor of the present invention may contain a well-known plasticizer in order to improve film-forming property, flexibility and mechanical strength. Examples of the plasticizer include phthalic acid esters, phosphoric acid esters, epoxy compounds, chlorinated paraffins, chlorinated fatty acid esters, and aromatic compounds such as alkylated naphthalene.

Needless to say, it may have an undercoat adhesive layer, an intermediate layer, and a photoreceptor surface protective layer, if necessary.

A photoreceptor using the azo pigment of the present invention has a high sensitivity and a good color sensitivity, and when repeatedly used, the sensitivity and the chargeability do not fluctuate, the light fatigue is small, and the durability is extremely excellent. Is.

Further, the photoconductor of the present invention can be widely used in electrophotographic application fields such as a photoconductor of a printer using a laser, a cathode ray tube (CRT), and a light emitting diode (LED) as a light source, in addition to an electrophotographic copying machine.

(E) Examples Next, the present invention will be described in more detail with reference to Examples.
The present invention is not limited to the following examples unless it exceeds the gist.

Example 1 Polyester film laminated with aluminum foil (Albet 85 made by Daido Kako, aluminum film thickness 10μ)
Vinyl chloride: vinyl acetate: maleic anhydride copolymer on a conductive support made of Sekisui Chemical's S-REC MF-10
An exemplary azo pigment N is formed to form an intermediate layer having a thickness of 0.05 μm.
2g of o.10 and 2g of butyral resin (3000K manufactured by Denki Kagaku Kogyo)
Are added to 200 ml of tetrahydrofuran and dispersed in a bain conditioner for about 1 hour, and the resulting azo pigment dispersion is applied and dried on the intermediate layer so that the film thickness after drying is 0.4 μ, and the carrier generating layer is obtained. To form a carrier transfer substance N, N-dibenzylaminobenzaldehyde-1,1-diphenylhydrazone 5g together with polyarylate resin 7g, a solution obtained by dissolving in 50 ml of monochlorobenzene so that the film thickness after drying becomes 19μ. After coating and drying, a carrier moving layer was formed to prepare an electrophotographic photoreceptor of the present invention. After this photoconductor was stored at room temperature in the dark at 30 ° C for one week, the electrophotographic photoconductor was attached to an electrostatic paper testing device "SP-428" (manufactured by Kawaguchi Denki Seisakusho) and the following characteristic tests were conducted. .

That is, a voltage of 6 KV was applied to the photosensitive layer to charge the photosensitive layer by corona discharge for 5 seconds, and the potential at that time was Vo (-V),
Then, the surface potential of the photosensitive layer is reduced to 1 / by irradiating light from a halogen lamp with the illuminance on the surface of the photosensitive layer being 30 lux.
The exposure dose E1 / 2 (lux · sec) required to attenuate to 2 was obtained.

The surface potential after exposure with an exposure amount of ₅₀ lux · sec, that is, the residual potential E ₅₀ (−V) was determined. 5 similar measurements
Repeated 00 times. The residual potential was completely reduced to 0 by further performing irradiation exposure with 300 lux for 0.3 seconds using a tungsten lamp as a light source for slowly discharging the residual potential.

 The results are shown in Table 1.

Examples 2 to 9 Examples of azo pigment No. 1 as a carrier generating substance,
A total of eight types of electrophotographic photoconductors were prepared in the same manner as in Example 1 except that No. 3, No. 7, No. 13, No. 15, No. 23, No. 26, and No. 33 were used. Then, the same characteristic test was performed for each of them.

 The results are shown in Table 2.

Example 11 2 g of Exemplified Azo Pigment No. 24 was added to 2 g of polyacrylate resin on the outer surface of a drum made of aluminum and having a diameter of 60 mm.
Was dissolved in 100 ml of tetrahydrofuran and dispersed using a paint conditioner for about 3 hours, and the resulting dispersion was coated and dried so that the film thickness after drying was 0.5 μm to form a carrier generation layer. Structural formula on this carrier generation layer Carrier transfer substance 4-N-ethyl-N-
(P-methylbenzyl), aminobenzaldehyde-1
-Phenyl-1-methylhydrazone 10g together with polycarbonate resin (Teijin Kasei Panlite L-1250) 12g
A solution dissolved in 100 ml of 1,2-dichloroethane was applied and dried so that the film thickness after drying was 15 μm to form a carrier moving layer, and a drum type electrophotographic photoreceptor according to the present invention was produced.

When this electrophotographic photosensitive member was mounted on a commercial machine-type electronic copying machine modified by our company and a copy image was formed, a high-contrast and clear visible image faithful to the original was obtained.

Further, copying was repeated 1000 times continuously, but a visible image equivalent to that of the first time was obtained until the end.

Example 12 The reflection spectrum of the drum-type electrophotographic photosensitive member obtained in Example 11 was measured by a spectrophotometer (UV-365 manufactured by Shimadzu) equipped with an integrating sphere, and the maximum absorption wavelength in the visible part of the photosensitive member was measured. Is 57
It was found to be around 0 nm to 620 nm.

Further, the spectral sensitivity of this photoconductor between 500 nm and 700 nm was measured using a monochromator, and the results are shown in FIG.

It was found that the photoconductor can withstand practical sensitivity even if a light emitting diode, a He-Ne laser and a halogen lamp are used as a light source.

Example 13 Styrene: n-butyl methacrylate: methacrylic acid copolymer (styrene: n-butyl methacrylate = 1: 2 weight ratio, acid value 250) and exemplified azo pigment No. on a grainy surface-oxidized Al plate. 41 and 2-phenyl-1-ethylindole-
Add 3-aldehyde-1 ', 1'-diphenylhydrazone to 1.
Blended in a weight ratio of 5: 0.2: 1.0, this in dioxane,
Dissolution (resin component, hydrazone compound) Dispersion (azo pigment)
The resulting liquid was applied and dried, and an electrophotographic characteristic test was conducted on the single-layer type photoreceptor having a film thickness of 6 μm by the above-mentioned electrostatic paper test apparatus.

 Applied voltage ＋ 6KV Vo ＝ 460Volt E1 / 2 ＝ 5.0lux ・ sec.

Further, the present photoreceptor is visualized with a developer (toner), and then an alkaline treatment aqueous solution (for example, 3% triethanolamine, 10% ammonium carbonate, 15% average molecular weight 190 to 210) is used.
Polyethylene glycol, 5% benzyl alcohol)
The non-toner-attached portion was easily eluted by the treatment (1), and then an original printing plate could be easily prepared by washing with water containing sodium silicate.

It was found that offset printing using this original plate can withstand printing of approximately 100,000 sheets.

The optimum exposure amount for obtaining a visible toner image (light source: halogen lamp) was 200 lux · sec, and when a printing original plate was prepared, direct plate-making was carried out without using a master plate material.

[Brief description of drawings]

FIG. 1 is a spectral sensitivity curve of the photoconductor of the present invention in Example 12.

Claims (3)

(57) [Claims] 1. An electrophotographic photosensitive member comprising a conductive support and a photosensitive layer containing an azo pigment represented by the following general formula [I]. (In the formula, A is hydrogen, an alkyl group which may have a substituent,
An aryl group which may have a substituent, a heterocyclic residue, a carboxylic acid and its ester, cyano, X represents hydrogen, cyano, halogen, lower alkyl, phenyl, and m represents 1
Or an integer of 2, n is an integer of 0 or 1, and Cp represents a coupler residue. ) 2. The photosensitive layer contains a carrier transfer substance and a carrier generating substance, and the carrier generating substance is an azo pigment represented by the general formula [I]. Electrophotographic photoreceptor. 3. The azo pigment represented by the general formula [I] is
Claim 1 which is a compound represented by the following general formula
Item. (In the formula, A, X, m and Cp have the same meanings as in the first term.)