JP3082430B2 - Electrophotographic photoreceptor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic photosensitive member. More specifically, the present invention relates to a highly sensitive electrophotographic photoreceptor containing a novel bisazo compound.

[0002]

2. Description of the Related Art As a photoreceptor for electrophotography, a photoreceptor using an inorganic photoconductive substance such as selenium, cadmium sulfide, or zinc oxide has been used. An organic photoconductive compound (hereinafter referred to as an organic photoconductive compound) having many advantages such as easy production and handling, good image quality, and easy obtaining of photosensitive members of various shapes such as drums, sheets and belts. A so-called OPC photosensitive member using OPC (abbreviated as OPC) 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,
It is inferior in sensitivity and durability, and is currently mainly used in low-speed machines. For this reason, development of OPC excellent in both sensitivity and durability is desired.

[0004]

Means for Solving the Problems The inventors of the present invention have proposed a novel O.S.
As a result of intensive studies on PC, 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 to provide the following general formula [I] or general formula [II] on a conductive support.

[0005]

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(Wherein, Ar ¹ , Ar ² and Ar ³ each represent an arylene group which may have a substituent or a divalent heterocyclic residue which may have a substituent, and Ar ¹ and Ar 2 ^Two
May be the same or different; K ¹ , K ² , K ³ and K ⁴ each represent a hydroxyl-containing coupler residue having a coupling ability, wherein K ¹ , K ² and K ³
And K ⁴ may be the same or different from each other; R ¹ and R ² each represent a hydrogen atom, a lower alkyl group, a lower alkoxy group or a halogen atom. The present invention relates to an electrophotographic photosensitive member having a photosensitive layer containing a bisazo compound represented by the formula (1).

Hereinafter, the present invention will be described in detail. The bisazo compound contained in the electrophotographic photoreceptor of the present invention has a structure represented by the general formula [I] or the general formula [II]. In the general formula [I] or the general formula [II], Ar ¹ ,
Ar ² and Ar ³ each represent an arylene group such as a phenylene group, a naphthylene group, or an anthracenylene group; a divalent pyrrole ring residue, a thiophene ring residue, or a divalent heterocyclic residue such as a furan ring residue; These may be the same or different from each other, and particularly preferably a phenylene group or a divalent thiophene ring residue. These arylene groups and divalent heterocyclic residues may have a substituent, and examples of the substituent include a hydroxyl group; a halogen atom such as a chlorine atom, a bromine atom and an iodine atom; a methyl group and an ethyl group. Alkyl groups such as propyl, butyl, and hexyl groups; alkoxy groups such as methoxy, ethoxy and butoxy groups; allyl groups; aralkyl groups such as benzyl, naphthylmethyl, and phenethyl groups; phenoxy groups, toloxy groups and the like Aryloxy groups such as benzyloxy group and phenethyloxy group; and aryl groups such as phenyl group and naphthyl group.

K ¹ , K ² , K ³ and K ⁴ are each a coupling residue containing a hydroxyl group having a coupling ability,
For example, groups of the following general formulas [III] to [VII] are exemplified. Note that the hydroxyl group having a coupling ability refers to 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 [III], X is condensed with a benzene ring to form a polycyclic aromatic ring such as a naphthalene ring, an anthracene ring, a carbazole ring, a benzocarbazole ring, a dibenzofuran ring, a benzonaphthofuran ring or a diphenylene sulfide ring. Or a residue necessary for forming a heterocyclic ring; R ³ and R ⁴ are 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; An aralkyl group such as a phenyl group, a phenethyl group or a naphthylmethyl group; an aryl group such as a phenyl group, a diphenyl group or a naphthyl group which may have a substituent; a carbazole group, a dibenzofuran group, a benzimidazolone group or a benzthiazole group , hetero groups, such as thiazole group, a pyridine group; and constitutes a cyclic amino group together with or bonded to the nitrogen atom of R ³ and R ⁴ Indicate that. R ³ and R ⁴ may be the same group or different groups, but from the viewpoint of sensitivity,
Preferably, one is a hydrogen atom and the other is a group other than a hydrogen atom.

[0011]

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In the general formulas [IV] and [V], R ⁵ represents an alkyl group, an aralkyl group or an aryl group which may have a substituent and is represented by the same examples as R ³ and R ⁴ .

[0013]

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Formulas [VI-a, b] and [VII-a, b]
In the formula, Y represents an aromatic hydrocarbon divalent group or a heterocyclic divalent group containing a nitrogen atom in the ring. Aromatic hydrocarbon 2
Examples of the valent 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, a 9,10-
Condensed polycyclic aromatic hydrocarbons such as phenanthrylene groups
And a valence group.

Examples of the divalent heterocyclic group containing a nitrogen atom in the ring include a 3,4-pyrazoldiyl group,
5 such as 2,3-pyridinediyl group, 5,5-pyrimidinediyl group, 6,7-indazolediyl group, 5,6-benzimidazolediyl group, 6,7-quinolinediyl group
Heterocyclic divalent groups containing 10 to 10 membered nitrogen atoms, preferably 2 or less nitrogen atoms, are included.

In consideration of sensitivity and durability, Y is an o-phenylene group, an o-naphthylene group, a peri-naphthylene group, a 2,3-pyridinediyl group, a 4,5-pyrimidinediyl group, especially an o-phenylene group. A phenylene group and an o-naphthylene group are preferred. In the present invention, the divalent group of the aromatic hydrocarbon and the divalent group of the heterocyclic ring containing a nitrogen atom in the ring used as Y may have a substituent. Examples of such a substituent include a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, an i-butyl group, and n
Alkyl groups such as hexyl group; alkoxy groups such as methoxy group, ethoxy group, propoxy group and butoxy group; hydroxyl group; nitro group; cyano group; amino group; substitution such as dimethylamino group, diethylamino group and dibenzylamino group. Amino group; halogen atom such as fluorine atom, chlorine atom, bromine atom, iodine atom; carboxyl group; alkoxycarbonyl group such as ethoxycarbonyl group; carbamoyl group; aryloxy group such as phenoxy group; arylalkoxy group such as benzyloxy group; And an aryloxycarbonyl group such as a phenyloxycarbonyl group. Among them, an alkyl group, an alkoxy group, a nitro group, a halogen atom, a hydroxyl group, and a carboxyl group, particularly, a methyl group, a methoxy group, a nitro group, a chlorine atom, and a hydroxyl group are preferred.

R ¹ and R ² in the general formula [I] or the general formula [II] each represent a lower alkyl group such as a methyl group, an ethyl group or a propyl group; a lower alkoxy group such as a methoxy group or an ethoxy group; And halogen atoms such as fluorine atom, bromine atom and the like. The bisazo compound of the present invention is, for example, the following general formula (VIII) or (IX)

[0018]

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Wherein Ar ¹ , Ar ² , Ar ³ , R ¹ and R ² have the same meanings as in the above general formulas [I] and [II]. It can be easily synthesized by coupling with a corresponding coupler. When the coupler residues K ¹ and K ² in the formula [I] or the coupler residues K ³ and K ⁴ in the formula [II] are respectively different groups, the corresponding two types of couplers may be mixed and used. Good.

According to a known method, the coupling reaction is usually carried out in water and / or an organic solvent such as dimethylformamide or dimethylsulfoxide at a reaction temperature of 30 ° C. or lower for about 1 hour to 10 hours. The aromatic diamine represented by the general formula [VIII] is, for example, A
When r ¹ = Ar ² , it is produced according to the following reaction formula.

[0021]

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The above reaction formula is described in detail.
The condensation is carried out by heating in acetic anhydride. Then
Known set of iron powder, zinc or tin chloride and acid such as hydrochloric acid, acetic acid
The compound (VIII) is obtained by reduction under combined conditions.
Can be produced in good yield. Ar ¹And Ar^TwoAre different
Is to mix the two corresponding nitraldehyde compounds
It may be used, but usually Ar¹= Ar^TwoPreferred compound
New

The aromatic diamine represented by the general formula [IX] is produced, for example, according to the following reaction formula.

[0024]

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The above reaction scheme is explained in detail. The compound [IX] can be produced in good yield by conducting condensation and then reducing under the same conditions as for the compound [VIII]. The electrophotographic photoreceptor of the present invention has a photosensitive layer containing one or more bisazo compounds represented by the above general formula [I] or [II]. 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 that the bisazo compound of the present invention is dispersed in a binder as a charge generating material,
This is used as a charge generation layer and contains a well-known charge carrier transport medium, a laminated type photoconductor in which a charge transport layer is laminated, or a single layer in which a well-known charge carrier transport medium is added to a dispersion layer of the above bisazo compound. Type photoreceptor.

The bisazo compound represented by the general formula [I] or [II] of the present invention has a high charge carrier generation efficiency and a high carrier injection efficiency into the charge carrier transporting medium, and is of the above-mentioned lamination type or single layer type. It has extremely excellent performance as a charge generation material for a function-separated type photoreceptor. The charge carrier transporting medium 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. Mixtures 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,
Examples include nitrated fluorenone such as 4,7-trinitrofluorenone and 2,4,5,7-tetranitrofluorenone or tetracyanomethane. Further, as a hole transport medium, an electron-donating organic photoconductive compound,
For example, heterocyclic compounds such as carbazole, indole, imidazole, oxazole, thiazole, oxadiazole, pyrazole, pyrazoline, and thiadiazole; triarylalkane derivatives such as triphenylmethane; triarylamine derivatives such as triphenylamine; phenylenediamine derivatives; N-phenylcarbazole derivatives; stilbene derivatives; hydrazone compounds, and the like. Particularly, substituted amino groups such as dialkylamino groups and diphenylamino groups, or electron-donating groups such as alkoxy groups and alkyl groups, or these electron-donating groups. A compound having a large electron donating property substituted with an aromatic ring group substituted with a donating group is exemplified. Also, like polyvinylcarbazole,
Polymers having a group consisting of these compounds in the main chain or side chain are also included. Among them, the hydrazone compound represented by the following general formula (XII)

[0027]

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[0028] (In the formula, Ar represents a phenyl group, a styryl group, a heterocyclic group such as an aromatic optionally substituted hydrocarbon group or carbazolyl group such as a naphthyl group, R ⁶
And R ⁷ are an alkyl group such as a methyl group and an ethyl group;
A hydrazone compound represented by an aryl group such as a phenyl group or a naphthyl group; an aralkyl group such as a benzyl group; at least one of R ⁶ and R ⁷ is an aryl group; and m represents 1 or 2). It is suitable.

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 above-mentioned laminated photoreceptor, a charge generation layer is usually formed on a conductive support, and a charge transport layer is formed thereon, but the structure 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 applied as a coating solution in a dispersed state. As a solvent for preparing a coating solution, basic solvents such as butylamine and ethylenediamine; ethers such as tetrahydrofuran and 1,4-dioxane; ketones such as methylethylketone and cyclohexanone;
Aromatic hydrocarbons such as xylene; aprotic polar solvents such as N, N-dimethylformamide, acetonitrile, N-methylpyrrolidone, dimethylsulfoxide; alcohols such as methanol, ethanol, isopropanol;
Esters such as ethyl acetate, methyl formate and methyl cellosolve acetate; and chlorinated hydrocarbons such as dichloroethane and chloroform.

When dispersing a bisazo compound, 1
It is necessary to make the particle size less than μm, preferably less than 0.5 μm. 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, polysulfone, polyvinyl acetal, polycarbonate, polyester, polyamide, polyurethane, Examples include cellulose ester, cellulose ether, epoxy resin, silicon resin and the like.

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 of the above-mentioned charge carrier transporting media are dissolved in the above-mentioned coating solution for the charge generating layer, and the conductive support is adjusted so that the film thickness after drying is 5 to 50 μm, preferably 10 to 30 μm. When applied on top, a single-layer type photoreceptor is obtained. The ratio of the bisazo compound to the binder polymer and the charge carrier transporting medium is usually 10 to 1000 parts by weight of the binder polymer per 10 parts by weight of the bisazo compound.
Parts by weight, preferably 30 to 500 parts by weight, and the charge carrier transporting medium 5 to 1000 parts by weight, preferably 20 to 50 parts by weight.
0 parts by weight.

In the laminated type photoreceptor, a charge transport layer is formed by applying a coating solution containing a charge carrier transport medium on the charge generation layer and drying it. When the charge carrier transporting medium 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. As the binder polymer, those described above are used, and the amount thereof is usually 50 to 3000 parts by weight, preferably 70 to 1 part by weight, per 100 parts by weight of the charge carrier transporting medium.
000 parts by weight.

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.

[0036]

Next, the present invention will be described more specifically with reference examples and examples, but the present invention is not limited to the following examples unless it exceeds the gist. In the Reference Examples and Examples, “parts” means “parts by weight”.

Reference Example 4.0 g of 2,4-dimethylquinoline, 7.7 g of p-nitrobenzaldehyde and 30 ml of acetic anhydride were mixed and heated under reflux for 9 hours. After the reaction, the precipitated crystals were collected by filtration and washed with methanol and then with ethyl acetate. This was recrystallized from 500 ml of N, N-dimethylformamide,
5.4 g of 2,4-bis (p-nitrostyryl) quinoline
Was obtained (melting point: 298 ° C., yellow crystals). This structure was confirmed by a mass spectrum and an infrared absorption spectrum. In the mass spectrum, a peak of M / e = 423 was observed, and in the infrared absorption spectrum, absorption of NO ₂ was observed.

Next, 3.9 g of the compound was reduced with tin chloride-hydrochloric acid in N, N-dimethylformamide to obtain 1.9 g of orange-yellow crystals (melting point: 293 ° C.). In the infrared absorption spectrum, the absorption of the nitro group disappeared. Elemental analysis values were as follows.

Table 1 As C ₂₅ H ₁₇ N ₃ O ₄ Calculated values: C 70.92%, H 4.05%, N
9.92% Found: C 71.04%, H 4.10%, N
9.81%

The above diamine (1.0 g) was added to water (15 ml) and concentrated hydrochloric acid (2.0 ml) and cooled. To this, 15% aqueous 10% sodium nitrite solution (15 ml) was added dropwise. It has become. Next, 2.3 g of 42% borofluoric acid was added to the solution, and the mixture was stirred at 5 ° C. or lower for 1 hour. The precipitated crystals were filtered, washed with a small amount of cold water, then with cold methanol, and dried to obtain 1.8 g of a tetrazonium salt. Obtained. 1.8 g of the tetrazonium salt was added to dimethyl sulfoxide 20.
of the compound of the following structural formula.

[0040]

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1.7 g of dimethyl sulfoxide in 250 ml
Was added to the reaction solution, and then a solution prepared by dissolving 2.5 g of sodium acetate in 15 ml of water was added to the reaction system. The mixture was further stirred for 3 hours, and the precipitated crystals were collected by filtration.

Next, the obtained bisazo compound is washed with dilute acetic acid, water and tetrahydrofuran and then dried.
The resulting solid was brownish and did not melt below 320 ° C. This was identified as the target bisazo compound from the results of elemental analysis and infrared absorption spectrum measurement (FIG. 1). The yield was 1.6 g and the elemental analysis values were as follows.

Table 2 As C ₆₁ H ₃₅ N ₉ O ₄ Calculated values: C 76.48%, H 3.68%, N
13.16% Found: C 76.33%, H 3.79%, N
13.10%

The bisazo compound was obtained as a mixture of the following compounds. In the following examples, when a group of the general formula [VI] or [VII] is introduced as a coupler residue, three isomers are similarly obtained, and one of these isomers will be described as a representative. I decided to.

[0044]

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The bisazo compound of the present invention used in the following Examples was synthesized according to this Reference Example or a method similar thereto.

Example 1 0.4 parts of a bisazo compound shown in Table 1 having a structure corresponding to the general formula [I] or [II] was dispersed together with 30 parts of cyclohexanone by a sand grinder, and polyvinyl butyral ( 0.4 parts of Sekisui Chemical Co., Ltd. (trade name: SREC) was added and dissolved. The obtained dispersion liquid of the bisazo compound was applied to a 75 μm-thick polyester film on an aluminum vapor-deposited layer by a wire bar so as to have a dry film thickness of 0.4 g / m ^2, and then dried. 90 parts of N-ethylcarbazole-3-aldehydediphenylhydrazone and a polycarbonate resin (Mitsubishi Kasei Corporation)
A solution prepared by dissolving 100 parts of NOVAREX 7525 (trade name) in 670 parts of dioxane was applied to a dry film thickness of 13 μm to form a charge transport layer. Thus, an electrophotographic photosensitive member having a two-layer photosensitive layer was obtained.

Table 1 shows the values of the half-life exposure (E1 / 2) as the sensitivity of these photosensitive members. The half-exposure amount was measured for the photoreceptor using an electrostatic copying paper test apparatus (Model SP-428 manufactured by Kawaguchi Electric Works). First -6.5 in the dark
It was charged by a corona discharge at kV and then exposed to white light with an illuminance of 5 lux, and the exposure required for the surface potential to attenuate to half of the initial surface potential was determined.

Examples 2 to 24 Except that the bisazo compounds shown in Tables 1, 2 and 3 were used instead of the bisazo compounds used in Example 1, respectively, An electrophotographic photoreceptor was obtained in the same manner. FIG. 2 shows an infrared absorption spectrum of the bisazo compound used in Example 18.

Tables 1, 2 and 3 show the half-life exposure values (E1 / 2) as the sensitivities of these photosensitive members. The half-life exposure amount was determined in exactly the same manner as shown in Example 1. The compounds in Tables 1 and 2 represent compounds in the case where Ar ¹ = Ar ^{2 in} the general formula [I], and the compounds in Table 3 indicate compounds represented by the general formula [II]. still,
The positions attached to the carbon atoms of the quinoline ring of R ¹ and R ² are indicated by the numbers attached to the following carbon atoms. However, when R ¹ and R ² are hydrogen atoms, no particular description is given.

[0050]

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For example, when R ¹ is a chlorine atom and is bonded to position 4,

Embedded image R ¹ ; represented as —Cl, 4.

[0052]

[Table 3]

[0053]

[Table 4]

[0054]

[Table 5]

[0055]

[Table 6]

[0056]

[Table 7]

[0057]

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. In particular, the sensitivity is better than a compound having the same type of coupler residue bonded thereto. The photosensitive member is suitable not only for an electrophotographic plain paper copying machine but also for a photosensitive member for a printer such as a laser printer, a liquid crystal, a shutter printer, and an LED printer, which require particularly stable and reliable performance.

[Brief description of the drawings]

FIG. 1 is an infrared absorption spectrum of a bisazo compound obtained in Reference Example (used in Example 7).

FIG. 2 is an infrared absorption spectrum of the bisazo compound used in Example 18.

Claims (1)

(57) [Claims] 1. A conductive support having the following general formula [I] or general formula [II] embedded image (Wherein, Ar ¹ , Ar ² and Ar ³ each represent an arylene group which may have a substituent or a divalent heterocyclic residue which may have a substituent, and Ar ¹ and Ar ² are the same K ¹ , K ² , K ³ and K ⁴ each represent a coupling residue containing a hydroxyl group having a coupling ability, wherein K ¹ and K ² and K ³ and K ⁴ are the same as each other. Wherein R ¹ and R ² each represent a hydrogen atom, a lower alkyl group, a lower alkoxy group or a halogen atom.) Photoreceptor.