JPH02287457A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To maintain high sensitivity and stable potential characteristics at the time of repeated use by incorporating an azo pigment obtained by azo coupling a cyclic compound having an active methylene group with an aromatic diazonium salt in a photosensitive layer. CONSTITUTION:The electrophotographic sensitive body contains in the photosensitive layer the azo pigment obtained by azo coupling the cyclic compound having the active methylene group with the aromatic diazonium salt and the azo pigment obtained by azo coupling combines with an electron attractive group directly with the alpha-, beta-, or gamma-position of the azo group in conjugation with the group, thus permitting sensitivity to be shifted to a longer wavelength side due to the intramolecular transfer of charge carriers, and intramolecular separation of the carriers to easily occur, and enhancement of sensitivity and stabilization of potential to be attained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an electrophotographic photoreceptor, and more particularly to an electrophotographic photoreceptor that provides improved electrophotographic properties.

[Conventional technology]

Conventionally, inorganic photoreceptors having a photosensitive layer containing selenium, cadmium sulfide, zinc oxide, etc. as main components have been widely used as electrophotographic photoreceptors. On the other hand, organic photoreceptors having a photosensitive layer containing an organic photoconductive compound as a main component have many advantages such as overcoming the above-mentioned drawbacks of inorganic photoreceptors, and have attracted attention in recent years.

Such organic photoreceptors include photoconductive polymers typified by boryl N-vinylcarbazole and 2.
Electrophotographic photoreceptors having a photosensitive layer mainly composed of a charge transfer complex formed from a Lewis acid such as 4,7-dolinitro-9-fluorenone have already been put to practical use. However, this photoreceptor is not necessarily satisfactory in sensitivity and durability.

On the other hand, functionally separated electrophotographic photoreceptors, in which the charge generation function and the charge transport function are divided into separate substances, have brought about significant improvements in sensitivity and durability, which had been considered shortcomings of conventional organic photoreceptors. Ta. Such a functionally separated photoreceptor has the advantage that there is a wide selection range of materials for each of the charge-generating substance and the charge-transporting substance, and that an electrophotographic photoreceptor having arbitrary characteristics can be produced relatively easily. .

Various azo pigments, phthalocyanine pigments, polycyclic bovine pigments, cyanine dyes, squaric acid dyes, pyrylium salt dyes, and the like are known as charge-generating substances. Among them, many structures have been proposed for azo pigments because of their strong light resistance, large charge generation ability, and ease of material synthesis. These azo pigments can generally be obtained by azo coupling with a coupler component having a phenolic hydroxyl group. Examples of such coupler components include naphthol couplers described in JP-A-47-37543, JP-A-56-94358, and JP-A-57-58154, and JP-A-58-122967. Benzocarbazole coupler described in, etc., JP-A-60
The naphthalimide coupler described in Japanese Patent Application Laid-Open No. 57-176055 and the perinone coupler described in Japanese Patent Application Laid-open No. 57-176055 are known.

There are many azo pigments manufactured using such coupler components (although they have been proposed, only a few have been put into practical use due to problems with sensitivity and potential stability during repeated use). .

[Problem that the invention seeks to solve]

An object of the present invention is to provide an electrophotographic photoreceptor that maintains practical high sensitivity and stable potential characteristics during repeated use and exhibits good image characteristics.

[Means for solving problems]

That is, the present invention provides an electrophotographic photoreceptor having a photosensitive layer on a conductive support, in which the photosensitive layer contains an azo pigment obtained by azo coupling of a cyclic compound having an active methylene group and an aromatic azonium salt. An electrophotographic photoreceptor characterized by containing:

The azo pigment obtained by azo coupling of the cyclic compound having an active methylene group and an aromatic azonium salt of the present invention is different from conventional naphthol-based azo pigments, etc., and is directly attached to the α-, β-, or γ-position of the bare azo group. Electron-withdrawing groups are conjugated and bonded. For this reason, longer wavelengths, increased extinction coefficients, and intramolecular charge separation easily occur due to intramolecular charge transfer.
It is believed that higher sensitivity and potential stability are achieved.

Further, cyclic compounds having an active methylene group include carbamoyl group, thiocarbamoyl group, carbonyl group, thiocarbonyl group, sulfone group, dicyanomethylenecarbonyl group,
Cyano group, nitro group, or aryl group such as benzene ring or naphthalene ring activated by an electron-withdrawing group such as cyano group, nitro group, trifluoromethyl group, or halogen atom (with at least one group) It is preferable to have an activated cyclic methylene group, and the effect is particularly remarkable in the compound represented by the following general formula (1).

General formula (1) - or may be different.

R1 and R2 are jointly a 5- to 7-membered carbocyclic compound such as a cyclopentane ring, a cyclohexane ring, a cyclohebutane ring, or a 5- to 7-membered carbocyclic compound such as a thiazoline ring, a barbyl ring, a hydantoin ring, a sulfascine ring, a diketopiperazine ring, etc.
Residues forming a membered heterocyclic compound, or jointly a benzene ring, a naphthalene ring.

A 5- to 7-membered carbocyclic compound such as a cyclopentane ring, a cyclohexane ring, a cyclohebutane ring, or 5-7
Residues forming a membered heterocyclic compound are shown.

The above R1 and R2 may have a substituent, and examples of these substituents include a nitro group, a cyano group, and chlorine.

Halogen groups such as fluorine and bromine, alkyl groups such as methyl, ethyl and propyl groups, aryl groups such as phenyl and naphthyl groups, aralkyl groups such as benzyl and phenethyl groups, alkoxy groups such as methoxy and ethoxy groups. , halogen-substituted alkyl groups such as trifluoromethyl group, trichloromethyl group, and dichloromethyl group.

A1. A2. p, a and A4 represent a hydrogen atom or a cyano group, k, j! , m and n each represent an integer of 0 or l.

Specific examples of the cyclic compound having an active methylene group used in the present invention are shown below.

Compound h CO NH h N-COCH3 NH -Ph OCH3 O2 -CH3 NH3 NH3 2H5 →+8 to 3r N N As the aromatic azonium salt to be azo-coupled with the cyclic compound having an active methylene group as the coupler component, diazonium Examples include salts, tetrazonium salts, hexazonium salts, octazonium salts, etc., which can be obtained as monoazo pigments, disazo pigments, trisazo pigments, and tetrakisazo pigments, respectively.

benzene, naphthalene, fluorene, phenanthrene,
Hydrocarbon aromatic rings such as anthracene and pyrene, furan, thiophene, pyridine, indole, benzothiazole, carbazole, acridone, dibenzothiophene,
Heteroaromatic rings such as benzoxazole, benzotriazole, oxadiazole, thiazole, etc., and those in which the above aromatic rings are bonded directly or with an aromatic group or a non-aromatic group, such as triphenylamine, diphenylamine, N-methyl Diphenylamine, biphenyl, terphenyl, binaphthyl, fluorenone, phenanthrenequinone, anthraquinone, benzanthrone, diphenyloxadiazole, phenylbenzoxazole, diphenylmethane, diphenylsulfone, diphenyl ether, benzophenone, stilbene, distyrylbenzene, tetraphenyl-p - It can be obtained from phenylenediamine, tetraphenylbenzidine, etc.

Examples of substituents that may be present on the aromatic hydrocarbon group or aromatic heterocyclic group that may be present through the bonding group include alkyl groups such as methyl, ethyl, propyl, butyl, alkoxy groups such as methoxy and ethoxy, and dimethylamino , dialkylamino groups such as diethylamino, radicals such as fluorine, chlorine, and bromine, hydroxyl groups, nitro groups, cyano groups, and methyl groups.

Next, the technical and physical aspects of the aromatic azonium salt used in the present invention are listed below. However, diazonium group (-N=N~
) is omitted and only the bonding position is shown.

Aromatic diazonium salt l-1 t I I-3 I-4 I-5 Al-7 AI-9 Al-10 AI Al-21 So Al-11 t Al-12 Al-13 Al-14 Tetrazonium salt h h A2 -45' Ti3 A2-46 A2 A2-56 H3 H3 A3-10 A3 A4-5 A4-6 Azo Pigment The azo pigment of the present invention is not limited to the above specific examples. As for the structure of the azo pigment of the present invention, for example, the azo pigment synthesized by the reaction of the cyclic compound 55 having an active methylene group and the aromatic azonium salt Al-1 has the following azo type and hydrazone type tautomerism. It has been confirmed from IR spectra that there is a hydrazone type. Which structure has priority in other azo pigments varies depending on the coupler structure, the substituent of the azonium salt, etc., but in the present invention, the hydrazone type is described for convenience. Specific examples of the azo pigment of the present invention are shown below.

NC CN Moreover, although only hydrazone type isomers are shown as specific examples of azo pigments, azo type or other possible tautomers may be used.

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

(Synthesis example) Azo pigment NCL26 was dissolved in 100mf of N,N-dimethylformamide.
Cooled to 0°C. To this solution was added 1 g (2.3 mmol) of tetrazonium salt N. After 2 minutes, 0.47 g (4.6 mmol) of triethylamine was added dropwise, and the mixture was stirred at 10° C. for 1 hour. Thereafter, the reaction solution was filtered, and the residue was washed with 100 mf of methanol and then vacuum-dried to obtain 0.5 g of a black-blue pigment.

The coating containing the azo pigment described above exhibits photoconductivity and can therefore be used in the photosensitive layer of the electrophotographic photoreceptor described above.

That is, in a specific example of the present invention, an electrophotographic photoreceptor can be prepared by forming a film on a conductive support by dispersing the azo pigment in a suitable binder.

In a preferred embodiment of the present invention, a photoconductive coating containing the above-mentioned specific azo pigment is used as a charge generation layer in an electrophotographic photoreceptor in which the photosensitive layer is functionally separated into a charge generation layer and a charge transport layer. can be applied.

The charge generating layer contains as much as possible of the above-mentioned specific azo pigment exhibiting photoconductivity in order to obtain sufficient absorbance;
In addition, in order to efficiently transport the generated charge carriers to the interface between the charge transport layer and the conductive substrate, a thin film layer, for example, 5 μm or less, preferably 0.01 μm-
A thin film layer having a thickness of 11t is desirable.

Binders that can be used to form the charge generating layer by coating can be selected from a wide variety of insulating resins, and can also be selected from organic photoconductive polymers such as poly-N-vinylcarbazole, polyviny/p-anthracene, and polyvinylpyrene. .

Preferably polyvinyl butyral, polyvinyl benzal, polyarylate (condensation polymer of bisphenol A and phthalic acid, etc.), polycarbonate, polyester, phenoxy resin, polyvinyl acetate, acrylic resin, polyacrylamide, polyamide, polyvinylpyridine, cellulose resin, Examples include insulating resins such as urethane resin, casein, polyvinyl alcohol, and polyvinylpyrrolidone. The resin contained in the charge generation layer is suitably 80% by weight or less, preferably 40% by weight or less.

The solvent that dissolves these resins varies depending on the type of resin, and is preferably selected from those that do not dissolve the underlying charge transport layer or undercoat layer.

Specific organic solvents include alcohols such as methanol, ethanol, and isopropanol, ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and dichlorohexanone, and N,N-dimethylformamide and N,N-dimethylacetamide. Amides, sulfoxides such as dimethyl sulfoxide, ethers such as tetrahydrofuran, dioxane, ethylene glycol monomethyl ether, esters such as methyl acetate, ethyl acetate, chloroform, methylene chloride, dichloroethylene, carbon tetrachloride, trichloroethylene, etc. Aliphatic halogenated hydrocarbons or benzene, toluene,
Aromatics such as xylene, monochlorobenzene, dichlorobenzene, etc. can be used.

Coating is done by dip coating method, spray coating method,
spinner coating method, blade coating method,
This can be done using a coating method such as a curtain coating method.

For drying, it is preferable to dry to the touch at room temperature and then heat dry. Heat drying at a temperature of 30 to 200℃ for 5 minutes to 2
Can be done stationary or under a blast of air for a range of hours.

The charge transport layer is electrically connected to the charge generation layer described above, and has the function of receiving and taking charge carriers injected from the charge generation layer in the presence of an electric field, and transporting these charge carriers to the surface. have.

In this case, the charge transport layer may be laminated on or below the charge generation layer.

As the charge transport substance, N-methyl-N-phenylhydrazino-3-methylidene-9-ethylcarbazole, N,
N-diphenylhydrazino-3-methylidene-1O-ethylphenothiazine, p-diethylaminobenzaldehyde-N, N-diphenylhydrazone, p-pyrrolidinobenzaldehyde-N.

Hydrazone compounds such as N-diphenylhydrazone, p-diethylbenzaldehyde-3-methylbenzthiazolinone-2-hydrazone, 2,5-bis(p-diethylaminophenyl)-1,3,4-oxadiazole, l -phenyl-3-(p-diethylaminostyryl)
-5-(p-diethylaminophenyl)pyrazoline, 1
-(pyridyl(2))-3-(p-diethylaminostyryl)-5-(p-diethylaminophenyl)pyrazoline, 1-(pyridyl(3))-3-(p-diethylaminostyryl)-5-(p- diethylaminophenyl)
Pyrazoline, l-[pyridyl(2))-3-(p-diethylaminostyryl)-4-methyl-5-(p-diethylaminophenyl)pyrazoline, 1-phenyl-3-
(p-diethylaminostyryl)-4-methyl-5-(
Pyrazoline compounds such as p-diethylaminophenyl) pyrazoline and spiropyrazoline, α-phenyl-4-
N.

N-diphenylaminostilbene, N-ethyl-3(α
-phenylstyryl)carbazole, 9-dibenzylaminobenzylidene-9H-fluorenone, 5-p-ditolylaminobenzylidene-5H-dibenzo (a, d)
Styryl compounds such as cycloheptene, 2-(p-diethylaminostyryl)-6-dinithylaminobenzoxazole, 2-(p-diethylaminophenyl)-
4-(p-dimethylaminophenyl") -5-(2-
Oxazole compounds such as chlorophenyl)oxazole, thiazole compounds such as 2-(p-diethylaminostyryl)-6-dinithylaminobenzothiazole, bis(4-diethylamino-2-methylphenyl)-
Triarylmethane compounds such as phenylmethane, 1
．． 1-bis(4-N,N-diethylamino-2-methylphenyl)hebutane, 1,1,2.2tetrakis(4-
Polyarylalkanes such as N,N-dimethylamino-2-methylphenyl)ethane, triphenylamine,
Poly-N-vinylcarbazole, polyvinylpyrene, polyvinylanthracene, polyvinyl acridine, poly-
Examples include 9-vinylanthracene, pyrene-formaldehyde resin, and ethylcarbazole formaldehyde resin.

In addition to these organic charge transport materials, inorganic materials such as selenium, selenium-tellurium, and amorphous silicon can also be used.

Further, these charge transport substances can be used alone or in combination of two or more.

When the charge transport material does not have film-forming properties, a film can be formed by selecting an appropriate binder. Examples of resins that can be used as binders include acrylic resin,
Insulating resins such as polyarylate, polyester, polycarbonate polystyrene, acrylonitrile-styrene copolymer, acrylonitrile-butadiene copolymer, polyvinyl butyral, polyvinyl formal, polysulfone, polyacrylamide, polyamide, chlorinated rubber, or poly-N-vinylcarbazole, polyvinylanthracene , organic photoconductive polymers such as polyvinylpyrene, and the like.

Since the charge transport layer has a limit in its ability to transport charge carriers, it cannot be made thicker than necessary. - For boat fishing, it is 5 μm to 30 μm, but the preferred range is 8 μm.
~20 μm. When forming the charge transport layer by coating, an appropriate coating method as described above can be used.

A photosensitive layer having such a laminated structure of a charge generation layer and a charge transport layer is provided on a conductive support. Such conductive supports include metals in which the support itself has conductivity;
For example, aluminum, aluminum alloy, stainless steel, etc. can be used; other materials include plastics having a layer formed by vacuum deposition of aluminum, aluminum alloy, indium oxide, tin oxide, indium oxide-tin oxide alloy, etc., and conductive materials. A support in which conductive particles (e.g. carbon black, silver particles, etc.) are coated on plastic or the above-mentioned metals together with a suitable binder, a support in which plastic or paper is impregnated with conductive particles, a plastic containing a conductive polymer, etc. are used. be able to.

A subbing layer having barrier and adhesive functions may also be provided between the conductive support and the photosensitive layer. The bottom/separate layer is casein, polyvinyl alcohol, nitrocellulose, ethylene-acrylic acid copolymer, polyamide, (nylon 6, nylon 66, nylon 610, copolymerized nylon,
(alkoxymethylated nylon, etc.), polyurethane, gelatin, aluminum oxide, etc.

The thickness of the undercoat layer is 0.1 μm to 5 μm, preferably 0.1 μm to 5 μm.
A suitable thickness is 5 μm to 3 μm.

Further, as another specific example of the present invention, there may be mentioned an electrophotographic photoreceptor in which the above-mentioned azo pigment is contained in the same layer together with a charge transport substance. At this time, a charge transfer complex compound consisting of poly-N-vinylcarbazole and trinitrofluorenone can be used in addition to the above-mentioned charge transport substance.

The electrophotographic photoreceptor of this example can be produced by dispersing the azo pigment and charge transfer complex compound in a polyester solution dissolved in tetrahydrofuran and then forming a film thereon.

The pigment used in any electrophotographic photoreceptor contains at least one type of pigment, and its crystal form may be amorphous or crystalline.

In addition, if necessary, pigments with different light absorptions may be used in combination to increase the sensitivity of the photoreceptor, two or more types of azo pigments may be combined for the purpose of obtaining a panchromatic photoreceptor, or known dyes and pigments may be used in combination. It is also possible to use it in combination with selected charge generating substances.

The electrophotographic photoreceptor of the present invention can be used not only in electrophotographic copying machines, but also in a wide range of electrophotographic applications such as laser beam printers, CRT printers, LED printers, liquid crystal printers, and laser engraving.

Ball on the support ≦ On the aluminum substrate, apply a solution prepared by dissolving 5 g of methoxymethylated nylon resin (number average molecular weight 32,000) and 10 g of alcohol-soluble copolymerized nylon resin (number average molecular weight 29,000) in 95 g of methanol using a Mayer bar. A subbing layer having a thickness of 1 μm after drying was provided.

Next, 3 g of the above-exemplified azo pigment No. 6 was added to 95 ml of cyclohexanone with a butyral resin (butyralization degree 6).
Add 2 g of 3 mol%) to the dissolved solution and grind with a sand mill
Spread out time. This dispersion was applied onto the previously formed undercoat layer using a Mayer bar so that the film thickness after drying was 0.2 μm, and dried to form a charge generation layer.

Then, after holding the following structural formula for 1 second, the illuminance was 10j! It was exposed to UV light and its charging characteristics were investigated.

The charging characteristics are the surface potential (VO) and the exposure 11 (E) required to attenuate the potential by half after leaving it in the dark for 1 second
%) was measured. The results are shown in Table 1.

5 g of hydrazone compound and 5 g of polymethyl methacrylate resin (number average molecular weight 100,000) were mixed with 40 g of toluene.
The photoreceptor of Example 1 was prepared by dissolving this in ml and applying it onto the charge generation layer using a Mayer bar so that the dry film thickness would be 17 μm and drying to form a charge transport layer.

Photoreceptors corresponding to Examples 2 to 20 were similarly produced using other exemplary pigments shown in Table 1 in place of azo pigments No. 6 and 6.

The electrophotographic photoreceptor thus prepared was statically corona-charged at 15 KV using an electrostatic copying paper tester MODE ISP-428 manufactured by Kawaguchi Denki, and the results are shown in Table 1 in a dark place. It can be seen that the electrophotographic photoreceptors of the present invention all have sufficient charging ability and excellent sensitivity.

Support 1 and Length ≦ Eye Example 1.6. Using the electrophotographic photoreceptors prepared in Examples No. 12 and No. 20, fluctuations in bright area potential and dark area potential during repeated use were measured.

As a method, the photoreceptor was attached to the cylinder of an electrophotographic copying machine equipped with a -6.5 KV corona charger, an exposure optical system, a developer, a transfer charger, a static elimination exposure optical system, and a cleaner. This copying machine is configured to produce an image on transfer paper as a cylinder is driven. Using this copying machine, the initial dark area potential (V D ) and light area potential (VL)
, respectively -700V.

Amount of variation in dark area potential (ΔVO) and amount of variation in bright area potential (ΔVL) when set to around -200V and used 5000 times
was measured. The results are shown in Table 2. Note that a negative sign in the amount of change in potential represents a decrease in potential, and a positive sign represents an increase in potential.

Table 2 Examples Photoreceptor ΔVo (V) Δ”t, (V
) A polyvinyl alcohol film having a thickness of 0.5 μm was formed on the aluminum surface of an n-fat aluminum vapor-deposited polyethylene terephthalate film. Next, the disazo pigment dispersion used in Example 5 was applied onto the previously formed polyvinyl alcohol layer using a Mayer bar so that the film thickness after drying was 0.2 μm, and dried to form a charge generation layer. did.

Next, 4 g of a styryl compound represented by the structural formula and a polyarylate resin (
A solution obtained by dissolving 5 g of a condensation polymer of bisphenol A and terephthalic acid-isophthalic acid) in 40 ml of tetrahydrofuran was applied onto the charge generation layer so that the film thickness after drying was 20 μm, and dried to form a charge transport layer. . The charging characteristics and durability characteristics of the photoreceptor thus produced were measured by the same method as in Examples 1 and 21. The results are shown below.

V6; 690 (-V) E34; 1.0
(fux-sec) ΔV,;-2(V) ΔvL
A photoreceptor was prepared by applying the charge generation layer and charge transport layer of the photoreceptor prepared in Example 25 in the reverse order, and the charging characteristics were evaluated in the same manner as in Example 1. . However, the charging polarity was set to 10.

Vo; 650 (+V) E'4; 1.3 (I!ux 11 sec) On the support 11 and the charge generation layer prepared in Example 6, 5 g of 2,4.7-trinitro-9-fluorenone and poly- 4゜41-
Dioxydiphenyl-2,2'-propane carbonate (molecular weight 250,000) 6g to monochlorobenzene 7
A solution dissolved in 0 ml was applied and dried to give a film thickness of 15 μm after drying.

The electrophotographic photoreceptor thus produced was evaluated in the same manner as in Example 1. However, the charging polarity was set to +.

Vo; 650 (10 V) E3; 2.0 (fux-sec)
0) 5g to 70mj of tetrahydrofuran! to form a charge transfer complex. This charge transfer complex compound, 2 g of the above-mentioned azo pigment No. 24, 5 g of polyester resin (Vylon; manufactured by Toyobo), 70 g of tetrahydrofuran,
It was added to the solution dissolved in ml and dispersed. This dispersion was applied onto the undercoat layer prepared in Example 1 and dried to a film thickness of 18 μm.
A photosensitive layer was formed.

The thus produced photoreceptor was evaluated in the same manner as in Example 1. However, the charging polarity was set to 10.

Vo; 650 (+V) E'A; 2.3 (fuxesec) Tip: 1 A subbing layer was provided on an aluminum substrate in the same manner as in Example 1.

Next, a charge generation layer was formed in the same manner as in Example 1 using the above-mentioned azo pigment No. 9.

Next, a charge transport layer was formed in the same manner as in Example 1 using a triarylamine compound having the following structural formula to produce a photoreceptor. Azo pigment No.
Example 3 using other exemplary pigments shown in Table 3 in place of , 9
Photoreceptors corresponding to Nos. 9 to 47 were produced in the same manner. The surface potential (VO) and exposure amount (E'A) of the photoreceptor thus produced were measured in exactly the same manner as in Example 1. The results are shown in Table 3.

3rd table] 1 soup 47 2" mouth 2 The electrophotographic photoreceptors prepared in Examples 31, 32, 42, 44 and 46 were used in the same manner as in Example 21 to determine the amount of variation in bright area potential during repeated use ( ΔvL) and dark potential fluctuation f
f1(ΔV O) was measured. The results are shown in Table 4.

Table 4 Example Photoreceptor Na ΔVO(V) ΔVL(V
) Example 52 The photoreceptor prepared in Example 15 was subjected to a corona discharge of 15 KV. The surface potential at this time was measured (initial potential ■).
. Furthermore, the surface potential of this photoreceptor was measured after it was left in a dark place for 1 second. Sensitivity is determined by setting the potential v1 after dark decay to 1
Exposure amount required to attenuate to /2 (E!4.μJ/crr
Evaluation was made by measuring r). At this time, a gallium/aluminum/propylene ternary semiconductor laser (power output: 5 mW; oscillation wavelength: 780 nm) was used as a light source.

These results were as follows.

Vo: -700V V,: -695V Ey2: 1,0 μJ/crd Next, a laser beam printer (a reversal development type electrophotographic printer equipped with the same semiconductor laser as above) (
The above photoreceptor was set in a Canon LBP-CX), and an actual image forming test was conducted.

The conditions are as follows. −Surface potential after next charging; −7
Surface potential after 00V1 image exposure; -150V (exposure amount 2-011 J/c rrf), transfer potential; +700
V, developer polarity; negative polarity, process speed; 50mm
/sec, development conditions (development bias); -450V, image exposure scanning method; image scan, -exposure before next charging; 50fux-sec red entire surface exposure, image formation is performed by line scanning a laser beam according to the character signal and image signal. However, good prints were obtained for both text and images. Furthermore, when 3,000 images were printed continuously, stable and good prints were obtained from the initial stage up to 3,000 sheets.

〔Effect of the invention〕

As described above, by using the azo pigment of the present invention in a photosensitive layer, either the generation efficiency or the injection efficiency of carriers inside the photoreceptor, or both, can be improved.
A photoreceptor with excellent sensitivity and potential stability during repeated use can be obtained.

Claims (3)

[Claims] (1) In an electrophotographic photoreceptor having a photosensitive layer on a conductive support, the photosensitive layer contains an azo pigment obtained by azo coupling of a cyclic compound having an active methylene group and an aromatic azonium salt. An electrophotographic photoreceptor featuring: (2) The cyclic compound having an active methylene group is a carbamoyl group, thiocarbamoyl group, carbonyl group, thiocarbonyl group, sulfone group, dicyanomethylenecarbonyl group,
2. The electrophotographic photoreceptor according to claim 1, which has a cyclic active methylene group activated by at least one group selected from a cyano group, a nitro group, and an aryl group having an electron-withdrawing group. (3) A cyclic compound having an active methylene group has the general formula (1)
The electrophotographic photoreceptor according to claim 1, which is represented by: General formula (1) ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (In the formula, X^1 and , there are chemical formulas, tables, etc. ▼, ▲ there are mathematical formulas, chemical formulas, tables, etc. ▼, ▲ there are mathematical formulas, chemical formulas, tables, etc. ▼ or ▲ there are mathematical formulas, chemical formulas, tables, etc. ▼.Also, X^1
and X^2 may be the same or different. R^1
and R^2 are residues that jointly form a 5- to 7-membered carbocyclic compound or a 5- to 7-membered heterocyclic compound, or jointly fused with an aromatic ring group or a heterocyclic group to form a 5- to 7-membered ring Indicates a residue forming a carbocyclic compound or a 5- to 7-membered heterocyclic compound. A^1, A^2, A^3 and A^4 represent a hydrogen atom or a cyano group, and k, l, m and n each represent an integer of 0 or 1. )