JPH04251864A - Photosensitive body - Google Patents

Abstract

PURPOSE:To improve overall electrostatic characteristics and the sensitivity in particular. CONSTITUTION:This photosensitive body has a photosensitive layer contg. the azo pigment expressed by formula on a conductive base body. In the formula, Ar1, Ar2 and Ar3 respectively denote arylene groups, such as phenylene and naphthylene, which may have substituents; R1 and R2 respectively denote a hydrogen atom, alkyl group, hydroxyl group, etc.; X denotes-O-, -S-, -NR- or -CHR(R denotes a hydrogen atom or alkyl group) ; n denotes number of 0 or 1; Cp denotes a residual coupler group having a phenolic OH group. The separated function type photosensitive body provided with a charge generating layer and a charge transfer layer in this order on a conductive base is more preferable. The charge generating layer is formed to<=4/mum thickness and the charge transfer layer is formed to 3 to 50mum thickness in such a case.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photoreceptor used in electrophotography, and more particularly, to a photoreceptor having a photosensitive layer made of an azo pigment.

0002

2. Description of the Related Art Conventionally, inorganic photoconductive materials such as selenium, cadmium sulfide, and zinc oxide have been known as materials constituting photosensitive layers in photoreceptors used in electrophotography and the like.

Although these inorganic photoconductive materials have many advantages, such as less charge dissipation in the dark or the ability to rapidly dissipate charge by light irradiation, they also have various disadvantages. ing. For example, selenium-based photoreceptors require difficult manufacturing conditions, are expensive to manufacture, and must be handled with care because they are susceptible to heat and mechanical shock. Furthermore, with zinc oxide photoreceptors and cadmium sulfide photoreceptors, stable sensitivity cannot be obtained in humid environments, and the dye added as a sensitizer causes charging deterioration due to corona charging and photofading due to exposure. Therefore, it has the disadvantage that it cannot provide stable characteristics over a long period of time.

On the other hand, the use of various organic photoconductive polymers such as polyvinylcarbazole as materials constituting the photosensitive layer has also been considered. However, although these organic photoconductive polymers are superior to the above-mentioned inorganic photoconductive materials in terms of film formability and light weight, they still lack sufficient sensitivity, durability, and stability due to environmental changes. In this respect, it was inferior to inorganic photoconductive materials.

In recent years, various research and developments have been carried out to solve these drawbacks and problems of photoreceptors, and the charge generation function and charge transport function of the photoconductive function are assigned to separate materials. Laminated or dispersed functionally separated photoreceptors have been developed.

[0006] Such functionally separated photoreceptors have a wide range of materials to choose from, and it is possible to combine the best materials in terms of electrophotographic properties such as charging characteristics, sensitivity, residual potential, repeatability, and printing durability. This makes it possible to provide a high-performance photoreceptor. Furthermore, since it can be produced by coating, it is possible to provide a photoreceptor with extremely high productivity and at low cost, and furthermore, by appropriately selecting the charge generating material, the sensitive wavelength range can be freely controlled. For example, charge-generating materials include organic pigments and dyes such as phthalocyanine pigments, cyanine pigments, polycyclic quinone pigments, perylene pigments, perinone pigments, indigo dyes, thioindigo dyes, and squalium pigments, as well as selenium, selenium/arsenic, selenium/
Inorganic materials such as tellurium, cadmium sulfide, zinc oxide, amorphous silicon, etc. can be used.

From this point of view, various azo pigments have been proposed as charge-generating substances (for example, Japanese Patent Application Laid-Open No. 1983-1999)
188042, JP-A-58-178363, JP-A-60-119566, etc.). JP-A-57-188042 discloses an electrophotographic photoreceptor having a photosensitive layer containing an azo compound represented by the following general formula: A-N=N-Ar1-N=N-Ar2. There is no specific relationship with azo pigments. JP-A-58-178363 has the following general formula;

[0008]

[Chemical 2]

An electrophotographic photoreceptor having a photosensitive layer containing an azo compound represented by the following has been disclosed, but it is structurally different from the azo pigment of the present invention. Japanese Patent Publication No. 60-119566
The publication has the following general formula;

0010

[C3]

An electrophotographic photoreceptor having a photosensitive layer containing an azo compound represented by the following has been disclosed, but it is structurally different from the azo pigment of the present invention.

However, even with functionally separated photoreceptors using various charge generators as described above, it is still not easy to obtain one that satisfies overall electrostatic properties, and the sensitivity is still insufficient. However, a photoreceptor with even better sensitivity and excellent overall electrostatic properties is desired.

[0013]

[Problems to be Solved by the Invention] The present invention was made in view of the above circumstances, and its object is to provide a photoreceptor that has excellent electrostatic properties in general and sensitivity in particular. be.

[0014]

[Means for Solving the Problems] The present invention relates to a photoreceptor characterized by having a photoreceptor layer containing an azo pigment represented by the following general formula [I] on a conductive substrate;

00
15]

[C4]

In the general formula [I], Ar1, Ar2 and A
Each of r3 represents an arylene group such as phenylene or naphthylene, and may have a substituent, for example, an alkyl group such as a methyl group or an ethyl group, or an alkoxy group such as a methoxy group or an ethoxy group.

R1 and R2 each represent a hydrogen atom, an alkyl group such as a methyl group or an ethyl group, an alkoxy group such as a methoxy group or an ethoxy group, a halogen atom (fluorine atom, chlorine atom, bromine atom, iodine atom, etc.), It represents a hydroxyl group or a nitro group, with a hydroxyl group being particularly preferred.

X is -O-, -S-, -NR- or -C
HR- (R is a hydrogen atom or an alkyl group);

[0019] n represents the number 0 or 1. Cp represents a coupler residue having a phenolic OH group, for example,
Those represented by the following general formulas [II] to [XI] can be used.

[0020]

[C5]

[0021]

[C6]

[In the formula, X1 is oxygen, sulfur, or a nitrogen atom which may have a substituent; Y is a divalent group of aromatic hydrocarbon or 2 which forms a heterocycle together with the nitrogen atom]
Valid group; Z is a residue that is fused with a benzene ring to form a polycyclic conjugated ring or a heterocycle; R3, R4, R6, R7
, R10, R11, R12, and R13 are hydrogen, or an alkyl group, an aralkyl group, an aryl group, or a heterocyclic group that may have a substituent, and each may be taken together to form a ring; R5, R14 represents an alkyl group, an aralkyl group, an aryl group, or a heterocyclic group, each of which may have a substituent; R8 and R9 represent hydrogen, a halogen atom, an alkyl group, an aralkyl group, each of which may have a substituent;
represents an acyl group, an alkoxycarbonyl group, an aryl group, a fused polycyclic group or a heterocyclic group; R15, R16 and R17, R18 are hydrogen, a halogen atom, an alkyl group,
It represents a nitro group, a substituted sulfone group, an optionally N-substituted carbamoyl group or sulfamoyl group, or an optionally substituted C-acylamino group or phthalimidyl group, and R15, R16, R17, and R18 together form a ring. may be formed].

In particular, the above general formulas [II], [IV], [
VII], [VIII], and [IX], R3, R6, R10, and R12 are hydrogen, and R
4, R7, R11, R13, R14 are the following general formula;

0
024]

[C7]

A substituted phenyl group represented by [wherein R19 is a substituent selected from a halogen atom, a nitro group, a cyano group, and a trifluoromethyl group] is preferred. In addition, specific examples of the coupler component used in the present invention include those represented by chemical formulas [1] to [45] shown below, but are not particularly limited thereto.

[0026]

[Chemical formula 8]

[0027]

[Chemical formula 9]

[0028]

[Chemical formula 10]

[0029]

[Chemical formula 11]

[0030]

[Chemical formula 12]

[0031]

[Chemical formula 13]

[0032]

[Chemical formula 14]

[0033]

[Chemical formula 15]

By incorporating the azo pigment represented by the above general formula [I] into the photosensitive layer, a photoreceptor with excellent sensitivity can be obtained. Here, the above general formula [I] of the present invention
The azo pigment represented by can be easily synthesized by a conventional method. That is, the following general formula [XII]

[
0035

[Chemical formula 16]

[In the formula, R1, R2 and Ar1, Ar2
, Ar3, n have the same meanings as in the case of [I] above] is diazotized using sodium nitrite-hydrochloric acid, and in the presence of an alkali, the amino compound represented by the above general formulas [II] to [X
I], or by diazotizing the amino compound, and then HB
It can be synthesized by adding an acid such as F4, isolating it in the form of a salt, and then performing a coupling reaction. Incidentally, the coupling is usually performed using water and/or N according to a known method.
, N-dimethylformamide or the like at a reaction temperature of 30 to 25° C. for 1 to 10 hours.

Further, the amino compound represented by the general formula [XII] can be prepared by a known method. That is, it can be produced, for example, according to the reaction formula shown below.

[0038]

[Chemical formula 17]

In the above reaction scheme for synthesizing the compound represented by the general formula [XII], sodium hydroxymethasulfonate is first reacted in an aqueous medium in order to protect the amino group.

On the other hand, diazotization of amines proceeds easily under normal conditions, and the product is isolated by performing salt exchange with HX (eg, HBF4, etc.).

The second coupling reaction is carried out in an aqueous medium by a known method. Finally, the product obtained as described above is dissolved in an aqueous solution of sodium hydroxide, potassium hydroxide, sodium carbonate, etc., and this is boiled to remove the protecting group of the amino group. ] An azoamino compound represented by the following is obtained.

In the present invention, when forming a photosensitive layer on a conductive support, the photosensitive layer contains one or more azo pigments represented by the general formula [I] produced as described above. .

By doing so, the azo pigment acts as a photoconductive substance, and when it absorbs light, it generates charge carriers with extremely high efficiency, thereby improving the sensitivity of the photoreceptor. Although the generated charge carriers can be transported using this azo pigment as a medium, it is more effective to transport them using a charge transporting material as a medium.

[0044] Here, the above-mentioned conductive support used in this photoreceptor may be a sheet-shaped or drum-shaped foil or plate of metal or alloy such as copper, aluminum, silver, iron, or nickel; A metal is attached to a plastic film by vacuum deposition, electroless plating, etc., or a layer of a conductive compound such as a conductive polymer, indium oxide, or tin oxide is coated or coated on a support such as paper or a plastic film. A material formed by vapor deposition, etc. can be used.

Further, various types of photoreceptors are known, and the photoreceptor of the present invention may be any of them.

For example, as shown in FIG. 1, a charge-generating material (3) and a charge-transporting material (2) are blended together with a binder on a conductive support (1) as described above, and photosensitive material is applied. Layer (4
), and as shown in Figure 2,
The photosensitive layer formed on the conductive support (1) includes, in order, a charge generation layer (6) containing a charge generation material (3) and a charge transport layer (5) containing a charge transport material (2). As shown in FIG. 3, a photosensitive layer formed on a conductive support (1) has a function-separated layered photoreceptor in which the photoreceptors are laminated together, and a photosensitive layer formed on a conductive support (1) is charged. Even if it is a functionally separated laminated photoreceptor in which a charge transport layer (5) containing a transport material (2) and a charge generation layer (6) containing a charge generation material (3) are laminated in sequence. good.

Furthermore, as shown in FIG. 4, a photosensitive layer (4)
A surface protective layer (7) is provided on the surface of the substrate, and an intermediate layer (8) is provided between the conductive support (1) and the photosensitive layer (4) as shown in Figure 5. It may be. Incidentally, if an intermediate layer is provided between the conductive support and the photosensitive layer as shown in FIG. 5, it is possible to improve the adhesion and coating properties between the conductive support and the photosensitive layer, and It becomes possible to improve the protection of the conductive support and the injection of charge from the conductive support to the photosensitive layer. Further, such a surface protective layer and an intermediate layer can also be provided in the functionally separated type laminated photoreceptor described above.

In the present invention, a functionally separated photoreceptor in which a charge generation layer and a charge transport layer are provided in this order on a conductive indicator is preferred. First, a case will be described in which a single-layer type photoreceptor as shown in FIG. 1 is manufactured as a photoreceptor according to the present invention.

In this case, fine particles of the azo pigment represented by the above general formula [I] are dispersed in a resin solution or a solution in which a charge transport compound and a resin are dissolved, and then dispersed on a conductive support. Apply it and let it dry. At this time, the thickness of the photosensitive layer is 3 to 30 μm, preferably 5 to 20 μm.
m. In addition, if the amount of azo pigment used is too small, the sensitivity will be poor, and if it is too large, the charging property will be poor and the mechanical strength of the photosensitive layer will be weakened. The total amount is 0.01 to 2 parts by weight, preferably 0.2 to 1.
The amount should be within the range of 2 parts by weight. In addition, when using a charge transporting material which itself can be used as a binder, such as polyvinyl carbazole, the amount of the azo pigment added is 0.01 to 1 part by weight per 1 part by weight of the charge transporting material.
It is preferable to adjust the amount to 0.5 part by weight.

Next, as a photoreceptor according to the present invention, a second
A case of manufacturing a laminated photoreceptor as shown in the figure will be described.

In this case, a coating solution prepared by dispersing the above azo pigment in a solution of a resin is applied onto the conductive support and dried to coat the conductive support. A charge generation layer is formed thereon. In this case, the thickness of this charge generation layer is set to be 4 μm or less, preferably 2 μm or less.

[0052] Then, a solution containing a charge transport material and a binder is applied onto the charge generation layer thus formed and dried to form a charge transport layer.

In this case, the thickness of the charge transport layer is 3 to 50 μm.
m, preferably 5 to 30 μm. Also,
The proportion of the charge transport material is 0.2 to 2 parts by weight, preferably 0.3 to 1.3 parts by weight, per 1 part by weight of the binder resin. Note that if the charge transport material is a polymeric charge transport material that itself can be used as a binder, no other binder resin may be used.

[0054] The binder resin used for producing the charge transport layer as described above is electrically insulating and may be a thermoplastic resin, a thermosetting resin, a photocurable resin, or a thermosetting resin, which is known per se.
Photoconductive resin etc. can be used. Suitable binder resins include, but are not particularly limited to, saturated polyester resins, polyamide resins, acrylic resins, ethylene-vinyl acetate copolymers, ionically crosslinked olefin copolymers (ionomers), Styrene-butadiene block copolymer, polycarbonate, vinyl chloride-vinyl acetate copolymer, cellulose ester, polyimide, thermoplastic agents such as styrene resin, epoxy resin, urethane resin, silicone resin, phenolic resin, melamine resin, xylene resin, Examples include thermosetting resins such as alkyd resins and thermosetting acrylic resins, photocurable resins, and photoconductive resins such as polyvinylcarbazole, polyvinylpyrene, polyvinylanthracene, and polyvinylpyrrole. Note that these binder resins can be used alone or in combination. It is desirable that these electrical insulation properties have a volume resistivity of 1×10 12 Ω·cm or more when measured alone.

In the photoreceptor of the present invention, in addition to the above binder resin, plasticizers such as halogenated paraffin, polychlorinated biphenyl, dimethylnaphthalene, dibutyl phthalate, O-terphenyl, chloranil, tetracyanoethylene, etc. , 2,4,7-trinitrofluorenone, 5,6-dicyanobenzoquinone, tetracyanoquinodimethane, tetrachlorophthalic anhydride, 3,5
- Electron-withdrawing sensitizers such as dinitrobenzoic acid, sensitizers such as methyl violet, rhodamine B, cyanine dyes, pyrylium salts, and thiapyrylium salts may be used.

Charge transporting materials used in the photoreceptor as described above include hydrazone compounds, pyrazoline compounds, styryl compounds, triphenylmethane compounds, oxadiazole compounds, carbazole compounds, stilbene compounds, enamine compounds, and oxazole compounds. ,
Various compounds such as triphenylamine compounds, tetraphenylbenzidine compounds, and azine compounds can be used. Specifically, for example, carbazole, N-ethylcarbazole, N-vinylcarbazole, N-phenylcarbazole, tetracene, chrysene, pyrene, perylene, 2-phenylnaphthalene, azapyrene, 2,3-benzochrysene, 3,4-benzopyrene, Fluorene, 1,
2-benzofluorene, 4-(2-fluorenylazo)
Resorcinol, 2-p-anisoleaminofluorene, p-diethylaminoazobenzene, cation, N,N
-dimethyl-p-phenylazoaniline, p-(dimethylamino)stilbene, 1,4-bis(2-methylstyryl)benzene, 9-(4-diethylaminostyryl)
Anthracene, 2,5-bis(4-diethylaminophenyl)-1,3,5-oxadiazole, 1-phenyl-3-(p-diethylaminostyryl)-5-(p-diethylaminophenyl)pyrazoline, 1-phenyl -3
-Phenyl-5-pyrazolone, 2-(m-naphthyl)-
3-phenyloxazole, 2-(p-diethylaminostyryl)-6-diethylaminobenzoxazole,
2-(p-diethylaminostyryl)-6-diethylaminobenzothiazole, bis(4-diethylamino-2
-methylphenyl)phenylmethane, 1,1-bis(4
-N,N-diethylamino-2-ethylphenyl)heptane, N,N-diphenylhydrazino-3-methylidene-10-ethylphenoxazine, N,N-diphenylhydrazino-3-methylidene-10-ethylphenothiazine, 1 , 1,2,2-tetrakis-(4-N,N-diethylamino-2-ethylphenyl)ethane, p-diethylaminobenzaldehyde-N,N-diphenylhydrazone, p-diphenylaminobenzaldehyde-N,N
-diphenylhydrazone, N-ethylcarbazole-N
-Methyl-N-phenylhydrazone, p-diethylaminobenzaldehyde-N-α-naphthyl-N-phenylhydrazone, p-diethylaminobenzaldehyde-3
-Methylbenzthiazolinone-2-hydrazone, 2-methyl-4-N,N-diphenylamino-β-phenylstilbene, α-phenyl-4-N,N-diphenylaminostilbene, 1,1-bis(P Charge transport materials such as -diethylaminophenyl)-4,4-diphenyl-1,3-butadiene are used alone or in combination of two or more.

When providing a surface protective layer as shown in FIG. 4, the material may be a polymer such as acrylic resin, polyaryl resin, polycarbonate resin, or urethane resin, or a low-carbon material such as tin oxide or indium oxide. It is appropriate to use a material in which a resistance compound is dispersed, and an organic plasma polymerized film can also be used.
It is also possible to include Group V atoms. Note that the thickness of the surface protective layer is preferably 5 μm or less.

In addition, when providing an intermediate layer as shown in FIG. 5, the material may be a polymer such as polyimide, polyamide, nitrocellulose, polyvinyl butyral, polyvinyl alcohol, or a low-carbon material such as tin oxide or indium oxide. Suitable materials include those in which a resistance compound is dispersed, and vapor-deposited films of aluminum oxide, zinc oxide, silicon oxide, and the like. In this case, the thickness of the intermediate layer is preferably 1 μm or less.

Note that the azo pigment represented by the general formula [I] acts particularly effectively as a charge-generating material for the laminated photoreceptor as described above.

[0060]

EXAMPLES Next, specific examples of the present invention will be explained, and comparative examples will be given to clarify that the photoreceptor according to the examples of the present invention is excellent. Synthesis Example As an azoamino compound represented by the general formula [XII], the following chemical formula (a);

[0061]

[Chemical formula 18]

The case of synthesizing the compound [0062] and an azo pigment represented by the general formula [I] consisting of the above chemical formula [1] as a coupler component will be explained in detail. Note that other azo pigments represented by the general formula [I] can also be synthesized in substantially the same manner. 3.5 g (0.01 mol) of the azoamino compound of the above compound (a) was dispersed in 200 ml of 18N hydrochloric acid, and this dispersion was cooled to a temperature of 5°C while stirring, and 1.4 g of sodium nitrite was added to 20 ml. An aqueous solution dissolved in water was added dropwise. After the dropwise addition was completed, stirring was continued under cooling for an additional hour to complete the reaction. Next, this was diluted with water to dissolve the diazo compound, filtered, and the resulting filtrate was added with borohydrofluoric acid 3
0 g was added, and the generated crystals were collected by filtration to obtain a diazonium salt, tetrafluoroborate.

Next, 4.5 g (0.01 mol) of the diazonium salt obtained as described above was added to 400 ml of dimethyl sulfoxide together with 3.1 g (0.012 mol) of the coupling agent shown in the chemical formula [1]. Dissolved. Then, a solution of 5 g of sodium acetate dissolved in 30 ml of water was added dropwise at room temperature over about 30 minutes. After the addition was completed, the mixture was stirred for another 3 hours at room temperature, and the precipitated crystals were collected by filtration. did.

Next, the obtained crude crystals were dispersed in 1 liter of deionized water and stirred at room temperature for 3 hours, and then the crystals were filtered again, further dispersed in 1 liter of DMF, and stirred at room temperature for 3 hours. After that, the crystals were filtered again. Two more washes with DMF
After repeating the process twice, the crystals were washed with water, dried, and heated at 80°C under reduced pressure.
4.8 g of azo pigment (yield 77.7
%) was obtained.

The azo pigment thus obtained was a reddish-purple crystal. In addition, elemental analysis of this azo pigment was performed, and the measured values and calculated values of each element (C37H26N6O4
) was compared. The results were as shown in Table 1 below.

[0066]

[Table 1]
Table 1 ────────────────────
────────
C H
N ────────────────────
──────── Example (%) 71.69
4.13 13.50 Calculated value (%)
71.84 4.21 13.5
9 ──────────────────────
──────Next, specific examples in which photoreceptors were produced using each azo pigment obtained as described above will be described.

Example 1 In this example, as the azo compound represented by the general formula [I],

[0068]

embedded image Ar2, Ar3 and coupler component Cp shown in Table 2 were used. Note that the Cp components are indicated by the numbers in the chemical formulas [1] to [45] described above. Then, 0.45 parts by weight of this azo pigment and polyester resin (Vylon 2
00: Toyobo Co., Ltd.) 0.45 parts by weight was dispersed with 50 parts by weight of cyclohexanone using a sand glider, and this dispersion was applied onto a 100 μm thick aluminized mylar using a film applicator, and this was dried. A charge generation layer having a film thickness of 0.3 g/m2 was formed.

Next, p-diphenylaminobenzaldehyde-N,
A solution of 70 parts by weight of N-diphenylhydrazone and 70 parts by weight of polycarbonate resin (K-1300: manufactured by Teijin Chemicals) dissolved in 400 parts by weight of 1,4-dioxane was applied, and this was dried to reduce the film thickness. A charge transport layer of 16 μm was formed.

In this way, in this example, a functionally separated laminated photoreceptor having a photosensitive layer consisting of two layers, a charge generation layer containing an azo compound as described above and a charge transport layer, was obtained. .

Examples 2 to 10 In these Examples, except that A, Ar2, Ar3 as the azo pigments contained in the charge generation layer and Cp as the coupler component shown in Table 2 were used. In exactly the same manner as in Example 1, two layers of charge generation layer and charge transport layer were prepared.
A functionally separated photoreceptor consisting of layers was manufactured. Note that the Cp components are indicated by the numbers in the chemical formulas [1] to [45] described above.

[0072]

[Table 2]

Examples 11 to 20 In these examples, A, Ar2, Ar3 as the azo pigments contained in the charge generation layer and Cp as the coupler component shown in Table 3 were used, and the charge transport material was as 1,1-bis(p-diethylaminophenyl)
A functionally separated photoreceptor consisting of two layers, a charge generation layer and a charge transport layer, was produced in the same manner as in Example 1 except that -4,4-diphenyl-1,3-butadiene was used. In addition,
The Cp components are shown by the numbers in the chemical formulas [1] to [45] described above.

[0074]

[Table 3]

Examples 21 to 30 In these examples, A, Ar2, Ar3 as the azo pigments contained in the charge generation layer and Cp as the coupler component shown in Table 4 were used, and the charge transport material was as N-ethylcarbazole-3-aldehyde-
The same procedure as in Example 1 was carried out except that N-methyl-N-phenylhydrazone was used.
A functionally separated photoreceptor consisting of layers was manufactured. Note that the Cp components are indicated by the numbers in the chemical formulas [1] to [45] described above.

[0076]

[Table 4]

Comparative Examples 1 to 7 In this comparative example, the following compounds (b) to (h) were used as charge generation materials, and the charge generation layer was formed in the same manner as in Example 1 except for the following. A functionally separated photoreceptor with a charge transport layer and a charge transport layer was fabricated.

Comparative example 1

[C20]

Comparative example 2

[C21]

Comparative example 3

[C22]

Comparative example 4

[C23]

Comparative Example 5

[C24]

Comparative Example 6

[C25]

Comparative Example 7

[C26]

Evaluation In order to compare the sensitivities of the photoreceptors of Examples 1 to 30 and Comparative Examples 1 to 7 produced as described above,
The half-decrease exposure amount E1/2 of each photoreceptor was measured. In addition, in measuring the half-life exposure amount E1/2, each photoreceptor in the previous period was first charged by -6.5 KV corona discharge, and then these photoreceptors were exposed to white light with an illuminance of 5 lux to determine the surface potential. The exposure amount (lux·sec) required to attenuate to half the initial surface potential and the attenuation rate DDR1 (%) of the initial surface potential (V0) when left in the dark for 1 minute were measured. The measurement results were as shown in Tables 5 and 6 below.

[0086]

[Table 5] ────────────────────────
────────
Vb E1/2 (lux・sec) DDR
1 (%) ────────────────────
──────────── Example 1 -
660 1.8 2.5
Example 2 -660 1.5
2.8 Example 3 -650
1.2 3.0 Example 4 -660 1.0
2.5 Example 5 -650
1.4 3.1 Example 6
-660 1.5
2.7 Example 7 -660
0.9 2.5 Example 8
-660 1.0 2.8
Example 9 -660 1.2
2.9 Example 10-65
0 1.7 3.2
Example 11 -650 1.4
3.2 Example 12 -660
1.3 2.7 Example 13
-660 0.9 2.
5 Example 14 -660 1.2
3.2 Example 15-66
0 1.7 2.4
Example 16 -660 0.9
2.5 Example 17 -650
0.8 3.0 ────────
────────────────────────

[
0087

[Table 6]
Table 6 ────────────
────────────────────
Vb E1/2(lu
x・sec) DDR1 (%) ────────
────────────────────────
Example 18 -650 0.9
2.9 Example 19 -660
1.3 2.4 Example 20 -660 1.0
2.6 Example 21 -640 1
．． 5 3.6 Example 22 -
650 1.2 2.9
Example 23 -660 1.3
2.4 Example 24-660
1.4 2.7 Example 25 -650 0.9
3.1 Example 26 -660 0
．． 8 2.4 Example 27 -
640 1.4 3.4
Example 28 -650 1.3
3.0 Example 29 -660
1.0 2.8 Example 30 -660 0.8
2.7 ────────────────────
──────────── Comparative example 1 -6
40 6.3 3.8
Comparative example 2 -650 8.5
3.2 Comparative Example 3 -650
4.6 3.0 Comparative example 4 -660 18.2
2.7 Comparative Example 5 -650 1
0.6 2.9 Comparative example 6
-650 8.2 3.1
Comparative example 7 -650 5.2
2.9 ────────────
────────────────────

[0088]

Effects of the Invention The photoreceptor containing the bisazo pigment represented by the general formula [I] of the present invention has excellent electrostatic properties, particularly sensitivity.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a dispersion type photoreceptor comprising a photosensitive layer laminated on a conductive support.

FIG. 2 is a schematic diagram of a functionally separated photoreceptor in which a charge generation layer and a charge transport layer are laminated on a conductive support.

FIG. 3 is a schematic diagram of a functionally separated photoreceptor in which a charge transport layer and a charge generation layer are laminated on a conductive support.

FIG. 4 is a schematic diagram of a photoreceptor in which a photosensitive layer and a surface protective layer are formed on a conductive support.

FIG. 5 is a schematic diagram of a photoreceptor in which an intermediate layer and a photosensitive layer are formed on a conductive support.

Claims (1)

[Claims] Claim 1: A photoreceptor comprising a photosensitive layer containing an azo pigment represented by the following general formula [I] on a conductive substrate; Ar3 each represents an arylene group which may have a substituent; R1 and R
2 is a hydrogen atom, an alkyl group, an alkoxy group,
Represents a halogen atom, hydroxyl group, or nitro group; X represents -O-, -S-, -NR- or -CHR- (R is a hydrogen atom or an alkyl group); Cp represents a phenolic O
Indicates a coupler residue having an H group; n represents a number of 0 or 1. ]