JPH10219126A - Bisazo compound and electrophotographic photoreceptor prepared therefrom - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a novel bisazo compd. which has a specified molecular structure, is excellent in sensitivity and durability, and is useful as an org. photoconductive compd. for an electrophotographic photoreceptor. SOLUTION: This compd. is represented by formula I (wherein R<1> and R<2> are each halogen, hydroxyl, cyano, nitro, optionally substd. alkyl, alkenyl, aralkyl, aryl, alkoxy, aryloxy, acyl, arylcarbonyl, alkyloxycarbonyl, substd. amino, thioether, or a heterocyclic group; m and n are each an integer of 0-4; and K<1> and K<2> are each a coupler residue having a hydroxyl group capable of coupling). K<1> and K<2> are exemplified by groups represented by formula II (wherein Y is a residue capable of combining with a benzene ring to form a fused ring; R<3> and R<4> are each independently H, optionally substd. alkyl, etc.; Z is O or S; and q is an integer of 0-2).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an electrophotographic photosensitive member. More specifically, the present invention relates to a novel bisazo compound and a highly sensitive electrophotographic photoreceptor containing the same.

[0002]

2. Description of the Related Art As an electrophotographic photoconductor, a photoconductor using an inorganic photoconductive substance such as selenium, cadmium sulfide, or zinc oxide has been used. Organic photoconductive compound (hereinafter referred to as OPC) having many advantages such as easy handling, good image quality, and easy to obtain photoconductors of various shapes such as drums, sheets and belts. The so-called OPC photoreceptor using OPC photoreceptors has been adopted for plain paper copiers and printers, and its ratio is increasing year by year.

[0003]

The OPC photoreceptor has many advantages over the conventional inorganic photoreceptor, but is inferior in sensitivity, durability and the like. It is used in the machine field. Therefore, development of OPC having excellent sensitivity and durability is desired. An object of the present invention is to provide a new OPC having such performance and a photoconductor using the same.

[0004]

SUMMARY OF THE INVENTION The present inventor has developed a novel OPC to obtain a high-sensitivity and high-durability electrophotographic photosensitive member.
As a result, the present inventors have found that a specific bisazo compound is suitable, and have reached the present invention. That is, the gist of the present invention is that the following general formula (I) is formed on a conductive support.

[0005]

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(Wherein R ¹ and R ² each represent a halogen atom, a hydroxyl group, a cyano group, a nitro group, an optionally substituted alkyl group, an alkenyl group, an aralkyl group, an aryl group, an alkoxy group, an aryloxy group, an acyl group Group, arylcarbonyl group, alkyloxycarbonyl group, substituted amino group, thioether group or heterocyclic group, m,
n represents an integer of 0 to 4. K ¹ and K ² represent a coupler residue containing a hydroxyl group having a coupling ability. ) And an electrophotographic photoreceptor comprising a photosensitive layer containing the bisazo compound.

Hereinafter, the present invention will be described in detail. In the general formula (I), R ¹ and R ² are a halogen atom; a hydroxyl group;
Cyano group; nitro group; alkyl group such as methyl group, ethyl group, propyl group, butyl group, decyl group; alkenyl group such as allyl group; aralkyl group such as benzyl group; aryl group such as phenyl group and naphthyl group; Alkoxy groups such as phenoxy groups; acyl groups such as acetyl groups; arylcarbonyl groups such as phenylcarbonyl groups; alkyloxycarbonyl groups such as methoxycarbonyl groups; methylamino groups, phenylamino groups, and diethylamino groups A thioether group such as a methylmercapto group; a heterocyclic group such as a pyridyl group or a thiophenyl group, and these groups may further have a substituent. As R ¹ and R ² , among these, a halogen atom, an alkyl group which may have a substituent or an aryl group is preferable. m,
n represents an integer of 0 to 4, and m = n = 0 is particularly preferable.

K ¹ and K ² are each a coupling residue containing a hydroxyl group having a coupling ability, and examples thereof include groups represented by the following general formulas (II) to (VI). The hydroxyl group having a coupling ability means a group that imparts a property capable of coupling with a diazonium salt to an aromatic ring or the like to which the hydroxyl group is bonded.

[0009]

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In the general formula (II), Y is condensed with a benzene ring to form a naphthalene ring, an anthracene ring, a carbazole ring,
R represents a residue required to form a polycyclic aromatic ring or a hetero ring such as a benzocarbazole ring, a dibenzofuran ring, a benzonaphthofuran ring, or a diphenylene sulfide ring;
³ and R ⁴ are each a hydrogen atom; an alkyl group such as a methyl group, an ethyl group, a propyl group or a butyl group which may have a substituent; a benzyl group, a phenethyl group or a naphthylmethyl group which may have a substituent; Aralkyl groups such as phenyl group, diphenyl group, and naphthyl group which may have a substituent; carbazole group, dibenzofuran group, benzimidazolone group, benzthiazole group, thiazole group,
A heterocyclic group such as a pyridine group; or R ³ and R ^{4 each} represent a cyclic amino group together with a nitrogen atom to be bonded. R ³ and R ⁴ may be the same group or different groups, but from the viewpoint of sensitivity, it is preferable that one is a hydrogen atom and the other is a group other than a hydrogen atom. Z represents an oxygen atom or a sulfur atom, and an oxygen atom is particularly preferred. q is 0,
Represents one of 1, 2 and 0 or 1 is preferable.

[0011]

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In the general formulas (III) and (IV), R ⁵
Represents a hydrogen atom, an alkyl group, an aralkyl group, an aryl group, and a heterocyclic group which may have a substituent represented by the same examples as R ³ and R ⁴ .

[0013]

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In the general formulas (Va, b) and (VI-a, b), W represents a divalent aromatic hydrocarbon group or a divalent heterocyclic group containing a nitrogen atom in the ring. Examples of the divalent aromatic hydrocarbon group include a divalent group of a monocyclic aromatic hydrocarbon such as an o-phenylene group; an o-naphthylene group, a peri-naphthylene group, a 1,2-anthraquinonylene group; 9,10
A divalent group of a condensed polycyclic aromatic hydrocarbon such as a phenanthrylene group;

The divalent heterocyclic group containing a nitrogen atom in the ring includes, for example, a 3,4-pyrazoldiyl group,
A nitrogen atom such as a 2,3-pyridinediyl group, a 4,5-pyrimidinediyl group, a 6,7-indazolediyl group, a 5,6-benzimidazolediyl group, a 6,7-quinolinediyl group, and preferably 2 or less And a 5- to 10-membered heterocyclic divalent group containing a nitrogen atom in the ring. In consideration of sensitivity and durability, W is an o-phenylene group,
o-naphthylene group, peri-naphthylene group, 2,3-
A pyridinediyl group and a 4,5-pyrimidindiyl group are preferable, and an o-phenylene group and an o-naphthylene group are particularly preferable.

Two of these aromatic hydrocarbons used as W
The divalent group of the heterocyclic ring containing a nitrogen atom and a nitrogen atom in the ring may further have a substituent. Examples of such a substituent include an alkyl group such as a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, an i-butyl group, and an n-hexyl group; a methoxy group, an ethoxy group, and a propoxy group. A hydroxyl group; a nitro group; a cyano group; an amino group; a substituted amino group such as a dimethylamino group, a diethylamino group, and a dibenzylamino group;
Halogen atoms such as fluorine, chlorine, bromine and iodine; carboxyl; alkoxycarbonyl such as ethoxycarbonyl; carbamoyl; aryloxy such as phenoxy; arylalkoxy such as benzyloxy; phenyloxycarbonyl And an aryloxycarbonyl group such as a group. Among them, alkyl group, alkoxy group, nitro group, halogen atom, hydroxyl group,
Carboxyl groups, particularly methyl, methoxy, nitro, chlorine, hydroxyl and the like are preferred.

The compound having a group of the formula (Va) is usually present as a mixture with an isomer having a group of the formula (Vb). Groups of type Va- and formula (Vb) are treated as the same group. Similarly, for the group of the formula (VI-a), (VI-a)
-B) Treated as the same group as the type group. These bisazo compounds, for example, the following general formula (VII)

[0018]

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(Wherein R¹, R^Two, M and n are the above-mentioned general formulas
A diamine represented by the following formula (I):
To the corresponding coupler and coupling
Can be easily synthesized. Such coupling
The reaction is carried out according to a known method, usually using water and / or dimethylphos.
In organic solvents such as lumamide and dimethyl sulfoxide,
React at a reaction temperature of 30 ° C or less for 1 to 10 hours.
You can do it. Coupler residue K¹And K^TwoDifferent from each other
The two corresponding couplers.
It may be used in combination. Note that two different couplers,
For example, selecting appropriate reaction conditions using k and k '
When the coupling reaction is performed, the following two isomer mixtures
Obtained in purity and at the same time¹= K^Two= Compound of k and K ¹
= K^Two= K 'are also mixed.

[0020]

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Next, the aromatic diamine represented by the general formula (VII) is specifically exemplified by, for example, the corresponding general formula (VI)
Produced by reducing the dinitro compound represented by II)

[0022]

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(Wherein R ¹ , R ² , m and n have the same meanings as in the above formula (I)) The reduction reaction is preferably performed under known reduction reaction conditions such as iron powder / hydrochloric acid and stannous chloride / hydrochloric acid. Will be implemented. General formula (VIII)
For example, as shown in the following reaction formula, a nitroanthranilic acid represented by the following general formula (IX-a) and a nitrobenzene acid chloride represented by the following (IX-b) are cyclized in the presence of a base. To be obtained. In the reaction formula, R ¹ , R ² , m, and n have the same meaning as in the general formula (I).

[0024]

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Typical examples of the bisazo compound of the general formula (I) useful as an electrophotographic photoreceptor are shown in Table 1 below, but the present invention is not limited to these compounds. In Table -1, if K ¹ and K ² are different,
Alternatively, in the case of a mixture of isomers, the compound of the formula (I) means a single compound or a mixture including the above-mentioned various mixtures.

[0026]

[Table 1]

[0027]

[Table 2]

[0028]

[Table 3]

[0029]

[Table 4]

[0030]

[Table 5]

The electrophotographic photoreceptor of the present invention has a photosensitive layer containing one or more bisazo compounds represented by the above general formula (I). The photosensitive layer is well known in various forms, but in the photosensitive member of the present invention, any of these types may be used. Particularly preferred is a layered photoreceptor in which the bisazo compound of the present invention is dispersed in a binder as a charge generating material, which is used as a charge generating layer, and which includes a well-known charge transporting material. A single-layer type photoconductor in which a well-known charge transporting material is added in a dispersion layer of a bisazo-based compound may be used.

The bisazo compound of the present invention represented by the general formula (I) has a high charge carrier generation efficiency and a high carrier injection efficiency into the charge transporting material, and is suitable for the above-mentioned laminated or single-layer type function-separated type photoreceptor. It has extremely excellent performance as a charge generation material. The charge transporting material used in combination with the bisazo compound of the present invention is generally classified into two types, an electron transporting medium and a hole transporting medium, and both can be used for the photoreceptor of the present invention. Can also be used. As an electron transport medium, an electron-withdrawing compound having an electron-withdrawing group such as a nitro group, a cyano group, and an ester group, for example, 2,4,7-trinitrofluorenone,
Examples include nitrated fluorenone such as 2,4,5,7-tetranitrofluorenone or tetracyanodimethane. Further, as a hole transport medium, an electron-donating organic photoconductive compound such as carbazole, indole,
Heterocyclic compounds such as imidazole, oxazole, thiazole, oxadiazole, pyrazole, pyrazoline, thiadiazole; triarylalkane derivatives such as triphenylmethane; triarylamine derivatives such as triphenylamine; phenylenediamine derivatives; N-phenylcarbazole derivatives Stilbene derivatives; hydrazone compounds, etc., particularly, substituted amino groups such as dialkylamino groups and diphenylamino groups, or electron-donating groups such as alkoxy groups and alkyl groups, or those substituted with these electron-donating groups. Compounds having a large electron donating property substituted by the substituted aromatic ring group. Further, a polymer having a group consisting of these compounds in a main chain or a side chain, such as polyvinylcarbazole, may also be used. Preferred compounds to be combined with the bisazo compound of the present invention include compounds as shown in Table 2 below.

[0033]

[Table 6]

[0034]

[Table 7]

[0035]

[Table 8]

[0036]

[Table 9]

[0037]

[Table 10]

[0038]

[Table 11]

[0039]

[Table 12]

[0040]

[Table 13]

The electrophotographic photoreceptor of the present invention can be manufactured according to a conventional method. That is, the electrophotographic photoreceptor of the present invention comprises:
On a conductive support, a laminate type having a charge generation layer and a charge transport layer containing the bisazo compound of the present invention, or a single layer type photosensitive member having a photosensitive layer in which a bisazo compound is dispersed, In addition, an intermediate layer such as an adhesive layer and a blocking layer, and a layer for improving performance such as electric characteristics and mechanical characteristics such as a protective layer may be provided. As the conductive support, any of those used in known electrophotographic photoreceptors can be used. Specific examples include metal drums and sheets of aluminum, copper, and the like, and laminates and vapor-deposits of these metal foils. Further, plastic films, plastic drums, paper, and the like, which are subjected to conductive treatment by applying a conductive substance such as metal powder, carbon black, copper iodide, and polymer electrolyte together with a suitable binder, may be used.
In addition, a conductive plastic sheet or drum containing a conductive substance such as metal powder, carbon black, or carbon fiber, or a plastic film having a conductive metal oxide layer such as tin oxide or indium oxide on its surface. And the like.

In the laminated type photoreceptor, usually, a charge generation layer is formed on a conductive support, and a charge transport layer is formed thereon, but the constitution may be reversed. The charge generation layer is formed by applying and drying a coating solution containing the bisazo compound of the present invention and a binder polymer. The bisazo compound may be dissolved but is usually used in a dispersed state. Basic solvents such as butylamine and ethylenediamine; ethers such as tetrahydrofuran and 1,4-dioxane; ketones such as methyl ethyl ketone and cyclohexanone; aromatic hydrocarbons such as toluene and xylene; 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 formate, methyl cellosolve acetate; dichloroethane, chloroform and the like Chlorinated hydrocarbons and the like can be mentioned.

When dispersing the bisazo compound in the coating solution, it is necessary that the particle size be 1 μm or less, preferably 0.5 μm or less. As the binder, styrene, vinyl acetate, acrylic acid ester, methacrylic acid ester, vinyl alcohol, polymers and copolymers of vinyl compounds such as ethyl vinyl ether, phenoxy resin,
Examples thereof include polysulfone, polyvinyl acetal, polycarbonate, polyester, polyamide, polyurethane, cellulose ester, cellulose ether, epoxy resin, and silicon resin.

The ratio of the bisazo compound to the binder polymer of the present invention is not particularly limited, but is generally 5 to 500 parts by weight, preferably 20 to 300 parts by weight, per 100 parts by weight of the bisazo compound. Use In addition to the above coating liquid, a dispersion stabilizer,
You may add a coating property improving agent, and also a dye, an electron-withdrawing compound, and other additives for improving performance. The thickness of the charge generation layer is 0.05 to 5 μm, preferably 0.1 to 2 μm.
μm.

One or more kinds of the above-mentioned charge transporting materials are dissolved in the above-mentioned coating solution for the charge generating layer, and the film thickness after drying is 5 to 5%.
A single-layer type photoreceptor can be obtained by applying it on a conductive support so that the thickness becomes 0 μm, preferably 10 to 30 μm. The ratio of the bisazo compound to the binder polymer and the charge transport material is usually 10 to 1000 parts by weight, preferably 3 to 10 parts by weight, per 10 parts by weight of the bisazo compound.
0 to 500 parts by weight, and the charge transporting material is 5 to 1000 parts by weight, preferably 20 to 500 parts by weight.

In the laminate type photoreceptor, a charge transport layer is formed on the charge generation layer by applying a coating solution containing an electric transport material and drying. When the charge transporting material is a polymer compound having a film forming property, a binder polymer may not be particularly used, but may be mixed for improving flexibility and the like. In the case of a low molecular compound, a binder polymer is used for forming a film. The above-mentioned binder polymer is used, and the amount thereof is generally in the range of 50 to 3000 parts by weight, preferably 70 to 1000 parts by weight, per 100 parts by weight of the charge transporting material. The charge transport layer has a thickness of 5 to 70 μm, preferably 10 to 50 μm.

In addition to the above, various additives can be used in the charge transport layer in order to improve the performance and the mechanical strength and durability of the coating film. Examples of such additives include electron-withdrawing compounds and dyes, stabilizers such as ultraviolet absorbers and antioxidants, coatability improvers, plasticizers, and crosslinking agents.
Examples of the electron-withdrawing compound include chloranil, 2,3-
Dichloro-1,4-naphthoquinone, 2-methylanthraquinone, 1-nitroanthraquinone, 1-chloro-5-
Quinones such as nitroanthraquinone, 2-chloroanthraquinone and phenanthrenequinone; aldehydes such as 4-nitrobenzaldehyde; 9-benzoylanthracene, indandione, 3,5-dinitrobenzophenone, 3,3 ', 5,5'-tetra Ketones such as nitrobenzophenone; acid anhydrides such as phthalic anhydride and 4-chloronaphthalic anhydride; tetracyanoethylene, terephthalalmalononitrile, 4-nitrobenzalmalononitrile, 4-benzoyloxybenzalmalonenitrile, 4
Cyano compounds such as-(p-nitrobenzoyloxy) benzalmalonenitrile; 3-benzalphthalide, 3-
(Α-cyano-p-nitrobenzal) phthalide, 3-
(Α-cyano-p-nitrobenzal) -4,5,6,7
And phthalides such as tetrachlorophthalide.

[0048]

EXAMPLES Next, the present invention will be described more specifically with reference to examples.
However, the present invention is not limited to the following examples unless it exceeds the gist.
However, the present invention is not limited to this. In the examples, "parts"
Means "parts by weight". Example 1 10.0 g of 4-nitroanthranilic acid was added to tetrahydrofuran.
Stir at 5 ° C during the run and add sodium carbonate 12.0
g and 25 g of 4-nitrobenzoyl chloride,
Stir at room temperature for 3 hours, add 150 ml of water, and add
While stirring. After filtering the precipitated solid, mix methanol and water
Wash sequentially with solvent, dimethylformamide and water mixed solvent
Thereafter, drying was performed to obtain 8.9 g of the dinitro compound (i). This
Has the molecular formula C₁₄H₇N_ThreeO₆Has a molecular weight of 3
13.22, and M / e = 313 in the mass spectrum.
The peak was confirmed. 8.0 g of this dinitro compound (i)
Was reduced with an iron / hydrochloric acid system, and purified with an alumina column.
2.7 g of min (ii) were obtained. This compound has the molecular formula C₁₄
H₁₁N_ThreeO _TwoHas a molecular weight of 253.26,
A peak at M / e = 253 was confirmed in the spectrum. element
The analysis values were as follows.

[0049]

Table 14 Calculated value as C ₁₄ H ₁₁ N ₃ O ₂ (%) C: 66.40 H: 4.38 N: 9.14 Measured value (%) C: 65.96 H: 4.07 N: 8.86

1.6 g of the above diamine (ii) was added to 75 m of water.
l, concentrated in 18 ml of concentrated hydrochloric acid, cooled, and 9.6 ml of a 10% aqueous solution of sodium nitrite was added dropwise thereto at 5 ° C or lower.
The mixture was stirred at 5 ° C or lower for 1 hour to form a tetrazo. Then 60
After adding 3.8 ml of hexafluorophosphoric acid and stirring at 5 ° C. or lower, the precipitated crystals were collected by filtration, washed sequentially with a small amount of cold water and cold methanol, and then dried to obtain 3.2 g of a tetrazonium salt. 0.7 g of the tetrazonium salt is dissolved in 10 ml of dimethyl sulfoxide, and 0.76 g of a coupler mixture represented by the following structural formula is dissolved in dimethyl sulfoxide 1
Add to the solution dissolved in 10ml, then react

[0051]

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2.3 g of a 30% aqueous sodium acetate solution was added to the system.
Was added, and the mixture was stirred for 3 hours, and the precipitated crystals were collected by filtration. After washing this with diluted acetic acid, water and tetrahydrofuran,
The solid (iii) obtained by drying has a black-purple color. Based on the elemental analysis values and the infrared absorption spectrum shown in FIG.
No. 1 It was identified as 1 bisazo compound. The yield was 0.48 g and the elemental analysis values were as follows.

[0053]

[Table 15] Calculated as _{C 50 H 25 N 9 O 6} (%) C: 70.84 H: 2.97 N: 14.87 measured value (%) C: 70.36 H: 2.79 N: 14.68

The bisazo compound of this example was obtained as a mixture of the following compounds. In the following examples, the general formula (Va), (Vb) or (VI
When the groups -a) and (VI-b) are introduced, four types of isomers are similarly obtained, and one of these isomers will be described as a representative.

[0055]

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Example 2 No. 1 in Table 1 synthesized in the same manner as in Example 1. 0.4 parts of each of the bisazo compounds 1 to 8 was added to 4-methyl-4-
Methoxypentanone-2 was dispersed together with 30 parts by a sand grinder, and 0.4 parts of polyvinyl butyral (trade name: BH-3, manufactured by Sekisui Chemical Co., Ltd.) was added and dissolved. The obtained bisazo compound dispersion was applied to a thickness of 75
It was applied and dried by a wire bar on an aluminum vapor-deposited layer vapor-deposited on a μm polyester film so as to have a dry film thickness of 0.4 g / m ² . 4,4'-Bis {N- [4- (α-styryl) phenyl] -N-phenylamino} diphenoxymethane 11 was added to the charge generation layer thus obtained.
A solution prepared by dissolving 0 parts and 110 parts of a polycarbonate resin (trade name: NOVAREX 7025, manufactured by Mitsubishi Chemical Corporation) in 670 parts of tetrahydrofuran was applied to a dry film thickness of 28 μm to form a charge generation layer. Thus, an electrophotographic photosensitive member having a two-layer photosensitive layer was obtained.

Table 3 shows the values of the half-life exposure amount (E1 / 2) as the sensitivity of these photosensitive members. The half-exposure amount was measured on the photoreceptor using an electrostatic copying paper test apparatus (Kawaguchi Denki Seisakusho model SP-428). First -6.5k in the dark
Charged by corona discharge at V, charged voltage at that time (V)
Was exposed to white light having an illuminance of 1 lux as the sensitivity (E1 / 2 (lux · sec)), and the amount of exposure necessary for the surface potential to attenuate to half of the initial surface potential was determined.

[0058]

[Table 16]

[0059]

The photoreceptor for electrophotography containing the bisazo compound of the present invention has high sensitivity and good color sensitivity, and particularly has little light fatigue. It has little fluctuation in potential, high stability, and extremely excellent durability. Not only electrophotographic plain paper copiers, but also laser printers, liquid crystals, shutter printers, and LEDs that require particularly stable and reliable performance
It is a photoconductor suitable for a photoconductor for a printer such as a printer.

[Brief description of the drawings]

FIG. 1 is an infrared absorption spectrum of the bisazo compound (iii) obtained in Example 1.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI G03G 5/06 352 G03G 5/06 352 367 367

Claims (6)

[Claims] 1. A bisazo compound represented by the following general formula (I). Embedded image (Wherein, R ¹ and R ² are each a halogen atom, a hydroxyl group, a cyano group, a nitro group, an optionally substituted alkyl group, an alkenyl group, an aralkyl group, an aryl group, an alkoxy group, an aryloxy group, an acyl group, Represents an arylcarbonyl group, an alkyloxycarbonyl group, a substituted amino group, a thioether group or a heterocyclic group, m and n each represent an integer of 0 to 4. K ¹ and K ² represent a coupler containing a hydroxyl group having a coupling ability. Represents a residue.) 2. K ¹ and / or K ² in the general formula (I)
Has the general formulas (II) to (VI-b): Embedded image (Wherein, Y represents a residue forming a condensed ring with a benzene ring, and R ³ , R ⁴ and R ⁵ each independently represent a hydrogen atom,
An alkyl group which may have a substituent, an aralkyl group,
It represents an aryl group or a heterocyclic group. Alternatively, R ³ and R ⁴ may form a cyclic amino group together with the nitrogen atom to be bonded. Z represents an oxygen atom or a sulfur atom, and q represents an integer of 0 to 2. W represents a divalent aromatic hydrocarbon group or a divalent heterocyclic group containing a nitrogen atom in the ring. The bisazo compound according to claim 1, wherein the compound is selected from the group consisting of: 3. K ¹ and / or K ² in the general formula (I)
Is selected from the group represented by the general formula (II). 4. K ¹ and / or K ² in the general formula (I)
Is selected from the groups represented by the general formulas (III) and (IV). 5. K ¹ and / or K ² in the general formula (I)
Are represented by the general formulas (Va), (Vb), (VI-a), (VI
The bisazo compound according to claim 2, wherein the bisazo compound is selected from the group represented by -b). 6. An electrophotographic photoreceptor comprising a photosensitive layer containing the bisazo compound according to claim 1 on a conductive support.