JP2658004B2 - Electrophotographic photoreceptor - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic photoreceptor, and more particularly, to an electrophotographic photoreceptor containing a charge generating substance that provides improved electrophotographic properties.

(Prior Art and Problems Thereof) Conventionally, as an electrophotographic photoreceptor, an inorganic photoreceptor having a photosensitive layer containing selenium, cadmium sulfide, zinc oxide or the like as a main component has been widely used.

These photoreceptors are not always satisfactory in heat stability, moisture resistance, durability, and the like. In particular, selenium and cadmium sulfide are restricted in production and handling due to toxicity.

On the other hand, an organic photoreceptor having a photosensitive layer containing an organic photoconductive compound as a main component has many advantages, such as compensating for the above-mentioned disadvantages of the inorganic photoreceptor, and has been receiving attention in recent years.

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

On the other hand, a function-separated type electrophotographic photoreceptor in which the charge generation function and the charge transport function are shared by separate substances has brought about remarkable improvements in sensitivity and durability, which have been disadvantages of conventional organic photoreceptors.

Such a function-separated type photoreceptor has an advantage that a material selection range of each of a charge generation material and a charge transport material is wide, and an electrophotographic photoreceptor having arbitrary characteristics can be relatively easily prepared. .

As the charge generating substance, various azo pigments, phthalocyanine pigments, polycyclic quinone pigments, cyanine dyes, squaric acid dyes, pyrylium salt dyes, and the like are known. Among them, many structures of azo pigments have been proposed from the viewpoints of high light resistance, high charge generation ability, easy material synthesis, and the like.

These azo pigments can be generally obtained by azo coupling of a coupler component having a phenolic hydroxyl group with a dianizonium salt. Examples of such a coupler component include, for example, JP-A-47-37543 and JP-A-5-37543.
6-94358, naphthol couplers described in JP-A-57-58154, benzocarbazole couplers described in JP-A-58-1222967, naphthalimide couplers described in JP-B-60-55941, JP-A-57-58154 A perinone coupler described in Japanese Patent No. -176055 is known.

Many azo pigments produced using such a coupler component have been proposed, but they have problems in sensitivity and stability of potential upon repeated use, and very few have been put to practical use.

Accordingly, an object of the present invention is to provide a novel electrophotographic photoreceptor.

A second 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 the Problems) The inventor of the present invention has studied to solve the above-described problems of the conventional art, and has reached the present invention.

That is, the present invention provides a method for activating a carbamoyl group, a thiocarbamoyl group, a thiocarbonyl group, a sulfone group, a dicyanomethylenecarbonyl group, a cyano group, a nitro group, or an aryl group having an electron-withdrawing group. An electrophotographic photoreceptor comprising a photosensitive layer containing an azo pigment obtained by azo-coupling a chain compound having an active methylene group and an aromatic diazonium salt.

(Action) The azo pigment used in the present invention containing a chain compound having a specific active methylene group as a coupler component is compared with a known naphthol azo pigment or the like at the α-position, β-position or γ-position of the azo group.
Since the electron-withdrawing group is directly conjugated and bonded to the position, the wavelength can be increased due to intramolecular charge transfer, the extinction coefficient can be increased, and the charge separation in the molecule can easily occur, so that high sensitivity can be achieved.

(Preferred Embodiment) The active methylene group of the chain compound in the present invention includes a carbamoyl group, a thiocarbamoyl group, a thiocarbonyl group, a sulfone group, a dicyanomethylenecarbonyl group,
Activated by at least two groups selected from an annealing group such as a benzene ring or a naphthalene ring activated by an electron-withdrawing group such as a cyano group, a nitro group or a cyano group, a nitro group, a trifluoromethyl group, and a halogen atom. ing. In particular, the effect is remarkable when the active methylene compound is a compound represented by the following general formula (1).

(Where X ¹ and X ² are Which may be the same or different. R ¹ and R ² are a cyano group, a nitro group, even if it has a substituent, a phenyl group, a naphthyl group, a phenanthryl group, a pyrenyl group or an aryl group such as a perylene group, a carbamoyl group, a thiocarbamoyl group, a pyridyl group or a quinolyl group shows the heterocyclic group and the ^{like, a 1, a 2, a} 3 and a ⁴ represents a hydrogen atom or a cyano group,
n and m each represent an integer from 0 to 2, and k and l each represent an integer of 0 or 1.

Examples of the substituent that R ¹ and R ² may have include a nitro group, a cyano group, a halogen group such as chlorine, fluorine or bromine, an alkyl group such as a methyl group, an ethyl group or a propyl group, a phenyl group or a naphthyl. And an aralkyl group such as a benzyl group or a phenethyl group; an alkoxy group such as a methoxy group or an ethoxy group; a halogen-substituted alkyl group such as a trifluoromethyl group, a trichloromethyl group or a dichloromethyl group.

Hereinafter, specific examples of the chain compound having an active methylene group used in the present invention will be shown.

As the azonium compound to be azo-coupled to the coupler component, a diazonium salt, a tetrazonium salt, a hexazonium salt, an octazonium salt, or the like can be used, and can be obtained as a monoazo pigment, a disazo pigment, a trisazo pigment, or a tetrakisazo pigment, respectively.

The azonium salt includes hydrocarbon aromatic rings such as benzene, naphthalene, fluorene, phenanthrene, anthracene and pyrene, furan, thiophenone, pyridine, indole, benzothiazole, carbazole, acridone, dibenzothiophenone, benzoxazole, benzotriazole, and oxa. Those obtained by further bonding the above aromatic ring directly or by an aromatic group or a non-aromatic group to a heteroaromatic ring such as diazole or thiazole, for example, triphenylamine, diphenylamine, N-methyldiphenylamine, biphenyl, Phenyl, binaphthyl, fluorenone, phenanthrenequinone, anthraquinone, benzanthrone, diphenyloxadiazole, phenylbenzoxazole, diphenylmethane, diphenylsulfone, diphenyle Ether, benzophenone, stilbene, distyryl benzene, tetraphenyl -p- phenylenediamine, can be obtained from tetraphenyl benzene and the like.

Examples of the substituent which the aromatic hydrocarbon group or the aromatic heterocyclic group may have via the above-mentioned bonding group include alkyl groups such as methyl, ethyl, propyl and butyl, alkoxy groups such as methoxy and ethoxy, and dimethyl. Examples thereof include a dialkylamino group such as amino and diethylamino, a halogen atom such as fluorine, chlorine and bromine, a hydroxy group, a nitro group, a cyano group and a halomethyl group.

Next, specific examples of the azonium salt used in the present invention are listed below. However, diazonium is omitted, and only the bonding position is shown.

Diazonium salt Tetrazonium salt Hexazonium salt Octazonium salt The azo pigment of the present invention is not limited by the above specific examples.

As the structure of the azo pigment of the present invention, for example, the following azo type and hydrazodone type tautomers exist in the azo pigment synthesized by the reaction of the active methylene compound 41 and the azonium salt A1-1. It has been confirmed from the IR spectrum that the hydrazone type has priority.

Which structure takes precedence in other azo pigments depends on
Although it varies depending on the synthesis conditions, the coupler structure, the substituent of the azonium salt, and the like, the azo type is described in the present invention for convenience.

 Hereinafter, specific examples of the azo pigment of the present invention are shown.

The specific examples of the coupler, the specific examples of the azonium salt, and the specific examples of the azo pigment do not limit the claims of the present invention.

Although only the azo type isomer is shown as a specific example of the azo pigment, it may be a hydrazone type or other possible tautomers.

 Next, synthesis examples of the azo pigment used in the present invention are shown below.

(Synthesis example) Malonic acid-m-nitrophenylamide 1.5g (4.9mmo
l) was dissolved in 100 ml of N, N-dimethylformamide at 10 ° C.
And cooled. Add the following tetrazonium salt to this solution 1 g (2.3 mmol) was added. After 2 minutes, 0.47 g of triethylamine
(4.6 mmol) 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 ml of methanol and then dried under vacuum to obtain 0.9 g of a black-blue pigment.

The coating having the above-mentioned azo pigment exhibits photoconductivity, and thus can be used for the photosensitive layer of the electrophotographic photosensitive member described below.

That is, in a specific example of the present invention, an electrophotographic photoreceptor can be prepared by dispersing and containing the azo pigment in a suitable binder on a conductive substrate to form a film.

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 photosensitive member in which a photosensitive layer of an electrophotographic photosensitive member is functionally separated into a charge generation layer and a charge transport layer. Can be applied.

The charge generation layer contains the above-mentioned specific azo pigment exhibiting as much photoconductivity as possible in order to obtain a sufficient absorbance, and the generated charge carrier forms an interface between the charge transport layer and the interface or the conductive substrate. Thin film layer, for example, 5 μm or less, preferably 0.01 to 1 μm for efficient transport to
It is desirable to form a thin film layer having a thickness of m.

This means that most of the incident light is absorbed by the charge generation layer to generate a large amount of charge carriers, and the generated charge carriers are not deactivated by recombination or trapping. This is due to the need to be injected.

The binder that can be used when forming the charge generation layer by coating can be selected from a wide range of insulating resins,
It can be selected from organic photoconductive polymers such as poly-N-vinylcarbazole, polyvinylanthracene and polyvinylpyrene.

Preferably, polyvinyl butyral, polyvinyl benzal, polyarylate (polycondensate of bisphenol A and phthalic acid, etc.), polycarbonate, polyester, phenoxy resin, polyvinyl acetate, acrylic resin, polyacrylamide, polyamide, polyvinyl pyridine, cellulose resin, Insulating resins such as urethane resin, casein, polyvinyl alcohol, and polyvinylpyrrolidone can be used. 80% by weight of resin contained in charge generation layer
Or less, preferably 40% by weight or less.

The solvent for dissolving these resins differs depending on the type of the resin, and is preferably selected from those which do not dissolve the charge transport layer and the undercoat layer described below.

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

Coating can be performed using a coating method such as a dip coating method, a spray coating method, a spinner coating method, a bead coating method, a Meyer bar coating method, a blade coating method, a roller coating method, and a curtain coating method.

Drying is preferably performed by touch drying at room temperature and then heating and drying. The heating and drying can be performed at a temperature of 30 to 200 ° C. for 5 minutes to 2 hours in a still or blown state.

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

At this time, the charge transport layer may be laminated on the charge generation layer, or may be laminated below.

As the charge transporting substance, there are an electron transporting substance and a hole transporting substance, and as the electron transporting substance, chloranil,
Tetracyanoethylene, tetracyanoquinodimethane, 2,
Electron-withdrawing substances such as 4,5,7-tetranitro-9-fluorenone, 2,4,5,7-tetranitroxanthone, 2,4,8-trinitrothioxanthone, and polymerizing these electron-withdrawing substances And others.

Examples of the hole transporting substance include pyrene, N-ethylcarbazole, N-ketyl-N-phenylhydrazino-3-methylidene-9-ethylcarbazole, N, N-diphenylhydrazino-3-methylidene-10-ethylpheno. Thiazone, p-diethylaminobenzaldehyde-N, N-diphenylhydrazone, p-pyrrolidinobenzaldehyde-
Hydrazones such as hydrazones such as N, N-diphenylhydrazone and p-diethylaminobenzaldehyde-3-methylbenzthiazolinone-2-hydrazone; 2,5-bis (p-diethylaminophenyl) -1,3,4-oxa Diazole, 1-phenyl-3- (p-diethylaminostyryl) -5- (p-diethylaminophenyl) pyrazolin, 1- [pyridyl (2)]-3- (p-diethylaminostyryl) -5- (p-diethylamino Phenyl) pyrazolin, 1- [pyridyl (3)]-3- (p-diethylaminostyryl) -5- (p-diethylaminophenyl) pyrazolin, 1- [pyridyl (2)]-3- (p-
Diethylaminostyryl) -4-methyl-5- (p-diethylaminophenyl) pyrazoline, 1-phenyl-3
-(P-diethylaminostyryl) -4-methyl-5-
Pyrazolines such as (p-diethylaminophenyl) pyrazolin and spiropyrazolin, α-phenyl-4-N, N-
Styryls such as diphenylaminostilbene, N-ethyl-3 (α-phenylstyryl) carbazole, 9-dibenzylaminobenzylidene-9H-fluorenone, 5-p-ditolylaminobenzylidene-5H-dibenzo [a, d] cycloheptene Compound, 2- (P-diethylaminostyryl) -6-diethylaminobenzoxazole, 2
Oxazole compounds such as-(p-diethylaminophenyl) -4- (p-dimethylaminophenyl) -5- (2-chlorophenyl) oxazole and thiazole compounds such as 2- (p-diethylaminostyryl) -6-diethylaminobenzothiazole Compounds, triarylmethane compounds such as bis (4-diethylamino-2-methylphenyl) phenylmethane, 1,1-bis (4-N, N-diethylamino-2-methylphenyl) heptane, 1,1,2, Polyarylalkanes such as 2-tetrakis (4-N, N-dimethylamino-2-methylphenyl) ethane, triphenylamine, poly-N-vinylcarbazole, polyvinylpyrene, polyvinylanthracene, polyvinylacridine, poly-9- Vinyl anthracene, pyrene-formaldehyde resin, ethyl carb Zol formaldehyde resin and the like. In addition to these organic charge transport materials,
Inorganic materials such as selenium, selenium-tellurium, amorphous silicon, and cadmium sulfide can also be used.

These charge transport materials can be used alone or in combination of two or more.

When the charge transport material does not have a film forming property, a film can be formed by selecting an appropriate binder. Resins that can be used as the binder include, for example, acrylic resin, polyarylate, polyester, polycarbonate, polystyrene, acrylonitrile-styrene copolymer, acrylonitrile-butadiene copolymer,
Insulating resin such as polyvinyl butyral, polyvinyl formal, polysulfone, polyacrylamide, polyamide, chlorinated rubber or poly-N-vinyl carbazole,
Organic photoconductive polymers such as polyvinyl anthracene and polyvinyl pyrene are exemplified.

Since the charge transport layer has a limit for transporting charge carriers, it cannot be made thicker than necessary. Generally, it is 5 to 40 μm, but a preferable range is 10 to 30 μm.
μm. When forming the charge transport layer by coating, an appropriate coating method as described above can be used.

A photosensitive layer having a laminated structure of such a charge generation layer and a charge transport layer is provided on a substrate having a conductive layer.
As such a substrate, a metal having conductivity itself can be used, and in addition, aluminum, an aluminum alloy, indium oxide, tin oxide, an indium oxide-tin oxide alloy, or the like is formed into a film by a vacuum evaporation method. Plastic having a layer (for example, polyethylene, polypropylene, polyvinyl chloride, polyethylene terephthalate, acrylic resin, polyfluoroethylene, etc.) can be used, and conductive particles (for example, carbon black, silver particles, etc.) can be used with an appropriate binder. In addition, a substrate coated on plastic, a substrate in which conductive particles are impregnated in plastic or paper, a plastic having a conductive polymer, or the like can be used.

An undercoat layer having a barrier function and an adhesive function may be provided between the conductive support and the photosensitive layer. The undercoat layer can be formed of 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 appropriate thickness of the undercoat layer is 0.1 to 5 μm, preferably 0.5 to 3 μm.

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

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

In any of the electrophotographic photoreceptors, the pigment to be used contains at least one kind of pigment, and the crystal thereof may be amorphous or crystalline.

If necessary, a combination of two or more types of azo pigments or a known dye may be used for the purpose of increasing the sensitivity of the photoreceptor or obtaining a panchromatic photoreceptor by using a combination of pigments having different light absorptions. Or a charge generation material selected from pigments.

The electrophotographic photoreceptor of the present invention can be widely used not only for electrophotographic copying machines but also for electrophotographic applications such as laser beam printers, CRT printers, LED printers, liquid crystal printers, and laser plate making.

(Examples) Next, the present invention will be described more specifically with reference to examples.

Examples 1 to 8 A solution prepared by dissolving 5 g of methoxymethylated nylon resin (average molecular weight: 32,000) and 10 g of alcohol-soluble copolymerized nylon resin (average molecular weight: 29,000) in 95 g of methanol was coated on an aluminum substrate with a Meyer bar, and dried An undercoat layer having a thickness of 1 μm was provided.

Next, 3 g of the above-mentioned azo pigment (No. 12) was added to a solution of 2 g of butyral resin (butyralization degree: 63 mol%) in 95 ml of cyclohexanone, and the mixture was dispersed in a sand mill for 20 hours. This dispersion was applied on a previously formed undercoat layer with a Meyer bar so as to have a thickness of 0.2 μm after drying, and dried to form a charge generation layer.

Then 5 g of a hydrazone compound of the following structural formula Polymethyl methacrylate resin (number average molecular weight 100,00
0) 5 g was dissolved in 40 ml of toluene, and this was coated on a charge generating layer with a Meyer bar so as to have a thickness of 17 μm after drying, and dried to form a charge transporting layer. Created body.

The photoreceptors corresponding to Examples 2 to 8 were prepared in exactly the same manner except that azo pigment No. 12 was replaced with the other exemplified pigments shown in Table 1 below.

The electrophotographic photoreceptor thus prepared was corona-charged at −5 Kv in a static manner using an electrostatic copying paper tester Moddel SP-428 manufactured by Kawaguchi Electric Co., Ltd., and held for 1 second in a dark place. Exposure was performed at 10 lux and charging characteristics were examined.

As the charging characteristics, the surface potential (V _O ) and the exposure amount (E _1/2 ) required to attenuate the potential after being left in a dark place for 1 second to 1/2 were measured. The results are shown in Table 1 below.

From these results, it can be seen that all the electrophotographic photoreceptors of the present invention have sufficient charging ability and excellent sensitivity.

Examples 9 to 12 Using the electrophotographic photoreceptors prepared in Examples 2, 6, 7, and 8, fluctuations in the light portion potential and the dark portion potential during repeated use were measured.

The photosensitive member was attached to a cylinder of an electrophotographic copying machine equipped with a corona charger of -6.5 KV, an exposure optical system, a developing device, a transfer charger, a charge-removal exposure optical system, and a cleaner. This copying machine is configured so that an image can be obtained on a transfer paper by driving a cylinder. Using this copier, the initial dark potential (V _D ) and the bright potential (V _L ) are calculated as follows:
The voltage was set at around 700 V and -200 V, and the amount of change in the light portion potential (ΔV _D ) and the amount of change in the light portion potential (ΔV _L ) were measured after 5,000 uses. The results are shown in Table 2 below. Note that a negative sign in the fluctuation amount of the potential indicates a decrease in the potential, and a positive sign indicates an increase in the potential.

Comparative Examples 1 to 4 Azo pigments 8, 15, 16 used in Examples 2, 6, 7 and 8
A photoreceptor was prepared in exactly the same manner as in Example 1, except that the following comparative azo pigments 1, 2, 3 and 4 were used in place of and
The charging characteristics similar to those in Examples 1 to 8 and the potential fluctuation during repeated use as in Examples 9 to 12 were measured, and the results are shown in Table 3 below.

Comparative pigment Examples 2, 6, 7, 9, 10 to 12 and Comparative Examples 1 to 4
Thus, it can be seen that the photoreceptor using the azo pigment of the present invention has a small sensitivity and a small potential fluctuation upon repeated use.

Example 13 A 0.5 μm-thick polyvinyl alcohol film was formed on an aluminum surface of an aluminum-deposited polyethylene terephthalate film. Next, the dispersion liquid of the disazo pigment used in Example 5 was applied to the previously formed polyvinyl alcohol layer with a Meyer bar so as to have a thickness of 0.2 μm after drying, and dried to form a charge generation layer. .

Then the structural formula A solution obtained by dissolving 4 g of a styryl compound represented by the following formula and 5 g of a polyacrylate resin (condensed polymer of bisphenol A and terephthalic acid-isophthalic acid) in 40 ml of tetrahydrofuran has a film thickness of 20 μm after being dried on the charge generation layer. And dried to form a charge transport layer. The charging characteristics and durability characteristics of the photoreceptors thus prepared were measured by the same methods as in Examples 1 and 9. The results are shown below.

V _O ; 690 (−v) E _1/2 ; 4.0 (lux.sec.) ΔV _D ; −5 (v) ΔV _L ; 2 (v) Example 14 Charge generation layer of the photoreceptor prepared in Example 13 A photoreceptor was prepared by applying the photoreceptor and the charge transport layer in reverse order, and the charging characteristics were evaluated in the same manner as in Example 1. However, the charging characteristic was +.

V _O ; 650 (+ v) E _1/2 ; 1.3 (lux.sec.) Example 15 On the charge generation layer prepared in Example 16, 5 g of 2,4,7-trinitro-9-fluorenone and 5 g of poly- 4,4'-dioxydiphenyl-2,2'-propane carbonate (molecular weight 25
(0,000) in 70 ml of monochlorobenzene was applied and dried so that the film thickness after drying was 15 μm.

The electrophotographic photosensitive member thus produced was evaluated in the same manner as in Example 1. However, the charging polarity was +.

V _O ; 650 (+ v) E _1/2 ; 3.0 (lux.sec.) Example 16 6,4,7-Trinitro-9-fluorenone 6g and poly-N
5 g of vinyl carbazole (number average molecular weight (350,000)) was dissolved in 70 ml of tetrahydrofuran to form a charge transfer destination compound. The charge transfer complex compound and 2 g of the azo pigment (No. 7) described above were mixed with a polyester resin (Viron; 5 g was dissolved in 70 ml of tetrahydrofuran and dispersed therein, and this dispersion was applied and dried on the undercoat layer prepared in Example 1 to form a photosensitive layer having a thickness of 18 μm.

The photosensitive layer thus formed was evaluated for the body in the same manner as in Example 1. However, the charging polarity was +.

V _O ; 650 (+ v) E _1/2 ; 4.5 (lux.sec.) Examples 17 to 20 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 azo pigment No. 9 described above.

Then, using a triarylamine compound having the following structure,
A charge transport layer was formed in the same manner as in Example 1 to prepare a photoreceptor.

Photoconductors corresponding to Examples 18 to 20 were prepared in exactly the same manner, except that azo pigment No. 9 was replaced with the other exemplified pigments shown in Table 3. The surface potential (V _O ) and the exposure amount (E _1/2 ) of the photoreceptor thus prepared were measured in exactly the same manner as in Example 1. The results are shown in Table 4.

Examples 21 to 24 Using the electrophotographic photoreceptors prepared in Examples 17 and 20, in the same manner as in Example 21, the amount of change in the bright portion potential (ΔV _L ) and the amount of change in the dark portion potential (ΔV _D ) during repeated use. ) Was measured. The results are shown in Table 5 below.

Example 25 The photoconductor prepared in Example 6 was subjected to a corona discharge of -5 KV. The surface potential at this time was measured (initial potential V _O ). Further, the surface potential of this photoconductor after leaving it in a dark place for 1 second was measured. Sensitivity, exposure required to attenuate the potential V ₁ of the after dark decay to 1/2 (E1 / 2, the micro-Joules / cm ²⁾ was evaluated by measuring. At this time, a ternary semiconductor laser of gallium / aluminum / arsenic (output: 5 mw; oscillation wavelength: 780 nm) was used as a light source. The results were as follows.

V _O ; -690V V ₁ ; -685V E _1/2 ; 1.5 microjoules / cm ² Next, a laser beam printer (Canon, LBP-CX, a reversal development type electrophotographic printer equipped with a semiconductor laser as described above) The above photoreceptor was replaced with a photoreceptor of LBP-CX and set, and an actual image forming test was used. The conditions are as follows.

Surface potential after primary charging: -700 V, surface potential after primary exposure; -150 V (exposure 2.0 μJ / cm ² ) transfer potential +700 V, developer polarity; negative polarity, process speed: 50 mm / sec., Development conditions ( -450 V, image exposure scan method; image scan, pre-charging pre-exposure; 50 lux · sec full red exposure, image formation was performed by line scanning laser beam according to character signal and image signal. Good prints were obtained for both images. Further, when 3,000 continuous images were output, stable and good prints were obtained from the initial stage to 3,000 pages.

(Effect of the Invention) As described above, by using the azo pigment of the present invention in the photosensitive layer, one or both of the carrier generation efficiency and the injection efficiency inside the photoconductor are improved,
A photosensitive member having excellent sensitivity and potential stability during repeated use can be obtained.

 ──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Nobuaki Kure 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (56) References JP-A-58-127933 (JP, A) JP-A-58 -194034 (JP, A)

Claims (2)

(57) [Claims] (1) activated by at least two groups selected from a carbamoyl group, a thiocarbamoyl group, a thiocarbonyl group, a sulfone group, a dicyanomethylenecarbonyl group, a cyano group, a nitro group and an aryl group having an electron-withdrawing group; An electrophotographic photosensitive member comprising a photosensitive layer containing an azo pigment obtained by azo coupling a chain compound having an active methylene group and an aromatic diazonium salt. 2. The electrophotographic photosensitive member according to claim 1, wherein the chain compound having an active methylene group is a compound represented by the following general formula (1). (Where X ¹ and X ² are And these may be the same or different. R ¹ and R ² represent a cyano group, a nitro group, an aryl group which may have a substituent, a carbamoyl group, a thiocarbamoyl group or a heterocyclic group, and A ¹ , A ² , A ³ and A ^{4 each} represent a hydrogen atom Or a cyano group, n and m each represent an integer from 0 to 2, and k and l
Represents an integer of 0 or 1. )