JPH0572769A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To enhance sensitivity in the total wavelength region of the total visible lights and characteristics against repeated uses by incorporating a specified bisazo compound as an electric charge generating material in a organic photosensitive layer. CONSTITUTION:The organic photosensitive layer formed on a conductive substrate contains as the charge generating material the bisazo compound represented by formula I in which each of R<1> and R<2> is, independently, O or S; each of R<3> and R<4> is, independently, H, alkyl, or aryl; each of mand n is, independently, 0, 1, or 2; and each of CP<1> and CP<2> is, independently, a coupler residue. This bisazo compound is prepared by diazotizing the N atoms of a pyrrolopyrrole skeleton through the ethylene chains and combining the couplers at those sites, thus permitting the spectral sensitivity characteristics to be changed by changing the electron density of the N-atoms and easily controlled.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic photosensitive member provided with an organic photosensitive layer on a conductive substrate, and more specifically, to an electrophotographic photosensitive member having high sensitivity and excellent repeatability over the entire visible light region. Regarding the body

[0002]

2. Description of the Related Art An organic photoconductor for electrophotography has a charge generation function and a charge transport function by using a charge generation material that generates a charge by light irradiation and a charge transport material that transports the generated charge. There is a so-called function-separated type that separates and. The function-separated type photoconductor includes a single layer type in which a photosensitive layer containing a charge generating material and a charge transporting material is formed on a conductive substrate, and a charge generating layer containing a charge generating material in a conductive substrate. And a charge transport layer containing a charge transport material is further laminated, or a charge generation layer in which the order of lamination is reversed.

As the above-mentioned charge generating material, conventionally,
Indigo pigments, perylene pigments, carbazole-based disazo pigments, oxazole-based disazo pigments and the like are used, and the bisazo compounds disclosed in JP-A-2-39159 and the bisazo compound disclosed in JP-A-3-11357 have been proposed. ..

[0004]

However, since the above charge generating material has a low charge generating efficiency, when this material is used as a charge generating material for an electrophotographic photoreceptor, the sensitivity is poor and Many of them have a narrow photosensitive wavelength region or have strong absorption in the near infrared region, have low sensitivity over the entire visible light region, and have poor repetitive characteristics. For this reason, it cannot be used, for example, as a photoreceptor for forming a color image.

The present invention is intended to solve the above-mentioned problems, and an object of the present invention is to provide an electrophotographic photosensitive member with a compound which is highly sensitive and has excellent repetitive characteristics over the entire visible light. It is to provide it as a generating material.

[0006]

The electrophotographic photosensitive member of the present invention is an electrophotographic photosensitive member in which an organic photosensitive layer is provided on a conductive substrate, and the organic photosensitive layer is represented by the following general formula as a charge generating material. It is characterized by containing a bisazo compound represented by (I), whereby the above object can be achieved.

[0007]

[Chemical 2]

(In the formula, R ¹ and R ² each independently represent an oxygen atom or a sulfur atom, R ³ and R ⁴ each independently represent a hydrogen atom, an alkyl group or an aryl group, and m and n each independently represents an integer of 0 to 2, and Cp ¹ and Cp ² each independently represent a coupler residue).

Next, the present invention will be described in detail.

In the bisazo compound represented by the general formula (I), R ¹ and R ² are each an oxygen atom or a sulfur atom, preferably an oxygen atom. R ¹ and R ² may be the same or different.

R ³ and R ⁴ are each a hydrogen atom, an alkyl group or an aryl group, preferably an aryl group. R ³ and R ⁴ may be the same or different.

As the coupler residue, the following (a) to (g) are preferable.

[0013]

[Chemical 3]

In the above coupler residue, R ⁵ is a hydroxyl group, —NR ¹¹ R ¹² (in the formula, R ¹¹ and R ¹² each independently represent a hydrogen atom or an alkyl group) or —N.
HSO ₂ R ¹³ (in the formula, R ¹³ represents a hydrogen atom or an alkyl group, an alkenyl group or an aryl group).

R ⁶ represents a hydrogen atom, a halogen atom, an alkyl group, an alkoxyl group, a carboxyl group, an alkoxycarbonyl group, a carbamoyl group, a sulfamoyl group or an aryl group, and the alkyl group or the alkoxyl group is a halogen atom, a phenyl group, It may have a substituent such as a naphthyl group, a nitro group and a cyano group. In addition, the carbamoyl group or the sulfamoyl group may have a substituent such as a halogen atom, a phenyl group, a naphthyl group, an alkyl group, an alkenyl group, a carbonyl group or a carboxyl group.

R ⁷ represents an atomic group necessary for being condensed with a benzene ring having R ⁵ and R ⁶ to form an aromatic ring, an aliphatic ring or a heterocycle, and these rings have the same substituents as described above. It may have a group.

R ⁸ represents a hydrogen atom, an amino group, an N-substituted amino group, an alkyl group, an alkenyl group, a hydroxyl group, a carbamoyl group, a carboxyl group or an alkoxycarbonyl group, and the alkyl group, the alkenyl group and the carbamoyl group are as defined above. You may have the same substituent.

R ⁹ represents a hydrogen atom, an alkyl group or an aryl group, and the alkyl group or the aryl group may have the same substituent as described above.

R ¹⁰ represents a phenylene group or a naphthylene group, which may have the same substituents as described above.

Examples of the alkyl group include alkyl groups having 1 to 6 carbon atoms such as methyl, ethyl, propyl, isobutyl, pentyl and hexyl. Examples of the alkenyl include alkenyl groups having 2 to 6 carbon atoms such as vinyl, allyl, 2-butenyl, 3-butenyl, 1-methylallyl, 2-penitenyl and 2-hexenyl. Examples of the halogen atom include fluorine, chlorine, bromine and iodine. The alkoxyl group includes, for example, methoxy, ethoxy, propoxy, isopropoxy, butoxy, isobutoxy, tert-butoxy, pentyloxy, hexyloxy and the like having 1 carbon atom.
To 6 alkoxyl groups. Examples of the alkoxycarbonyl group include lower alkoxycarbonyl having 1 to 6 carbon atoms in the alkoxy moiety such as methoxycarbonyl, ethoxycarbonyl, propoxycarbonyl, isopropoxycarbonyl, butoxycarbonyl, isobutoxycarbonyl, pentyloxycarbonyl and hexyloxycarbonyl. Groups.

In R ⁷ , the atomic group which is condensed with the benzene ring having R ⁵ and R ⁶ to form an aliphatic ring has 1 to 4 carbon atoms such as methylene group, ethylene group, propylene group and butylene group. The alkylene groups of In R ⁷ , the heterocycle formed by condensation with the benzene ring having R ⁵ and R ⁶ is benzofuranyl, benzothiophenyl, indolyl, 1H-indolyl, benzoxazolyl, benzothiazolyl, 1H-indazolyl, benzimidazolyl. , Chromenil, chromanil,
Isochromanyl, quinolinyl, isoquinolinyl, cinnolinyl, phthalazinyl, quinazolinyl, quinoxalinyl, dibenzofuranyl, carbazolyl, xanthenyl,
Acridinyl, phenanthridinyl, phenanthinyl,
Examples include phenaxazinyl and thianthrenyl. Further, Cp ¹ and Cp ² may be the same or different.

Examples of the bisazo compound of the present invention represented by the above general formula (I) include compounds shown in Tables 1-6.

[0023]

[Table 1]

[0024]

[Table 2]

[0025]

[Table 3]

[0026]

[Table 4]

[0027]

[Table 5]

[0028]

[Table 6]

The electrophotographic photosensitive member of the present invention is constituted by providing an organic photosensitive layer containing a bisazo compound represented by the general formula (I) as a charge generating material on a conductive substrate. The organic photosensitive layer may be a single layer or a plurality of layers (for example, a charge generation layer and a charge transport layer). Furthermore, a protective layer may be provided on the organic photosensitive layer, and an intermediate layer may be provided between the organic photosensitive layer and the conductive substrate. The bisazo compound may be used alone or in combination of two or more.

In the present invention, in addition to the bisazo compound represented by the general formula (I), a charge generating material may be contained, for example, selenium, selenium-tellurium, amorphous silicon, a conventionally known bisazo compound, Ansanthuron compound, phthalocyanine compound, indigo compound, triphenylmethane compound, slene compound,
Examples thereof include perylene compounds and quinacridone compounds.

Further, the organic photosensitive layer may contain a charge transport material. Examples of such charge transport materials include m-phenylenediamine compounds; tetracyanoethylene; fluorenone compounds such as 2,4,7, -trinitro-9-fluorenone; nitrated compounds such as dinitroanthracene; anhydrous amber. Acid; maleic anhydride; dibromomaleic anhydride; triphenylmethane compound; 2,5-di (4-dimethylaminophenyl)-
Oxadiazole compounds such as 1,3,4-oxadiazole; styryl compounds such as 9- (4-diethylaminostyryl) anthracene; carbazole compounds such as poly-N-vinylcarbazole; 1-phenyl-3 −
Pyrazoline compounds such as (p-dimethylaminophenyl) pyrazoline; 4,4 ′, 4 ″,-tris (N, N-)
Amine derivatives such as diphenylamino) triphenylamine; 1,1-bis (4-diethylaminophenyl)-
Conjugated unsaturated compounds such as 4,4-diphenyl-1,3-butadiene; hydrazone compounds such as 4- (N, N-diethylamino) benzaldehyde-N, N-diphenylhydrazone; indole compounds, oxazole compounds, iso Oxazole compounds, thiazole compounds,
Examples thereof include nitrogen-containing cyclic compounds such as thiadiazole compounds, imidazole compounds, pyrazole compounds, pyrazoline compounds, and triazole compounds; condensed polycyclic compounds and the like.

The following compounds are exemplified as the m-phenylenediamine compound. N, N, N ',
N'-tetraphenyl-1,3-phenylenediamine,
N, N, N ', N'-tetrakis (3-tolyl) -1,
3-phenylenediamine, N, N, N ', N'-tetraphenyl-3,5-tolylenediamine, N, N, N',
N'-tetrakis (3-tolyl) -3,5-tolylenediamine, N, N, N ', N'-tetrakis (4-tolyl) -1,3-phenylenediamine, N, N, N',
N'-tetrakis (4-tolyl) -3,5-tolylenediamine, N, N, N ', N'-tetrakis (3-ethylphenyl) -1,3-phenylenediamine, N, N,
N ', N'-tetrakis (4-propylphenyl)-
1,3-phenylenediamine, N, N, N ', N'-tetraphenyl-5-methoxy-1,3-phenylenediamine, N, N-bis (3-tolyl) -N', N'-diphenyl- 1,3-phenylenediamine, N, N'-bis (4-tolyl) -N, N'-diphenyl-1,3-phenylenediamine, N, N'-bis (4-tolyl) -N,
N'-bis (3-tolyl) -1,3-phenylenediamine, N, N'-bis (4-tolyl) -N, N'-bis (3-tolyl) -3,5-tolylenediamine, N , N '
-Bis (1-ethylphenyl) -N, N'-bis (3-
Ethylphenyl) -1,3-phenylenediamine, N,
N'-bis (4-ethylphenyl) -N, N'-bis (3-ethylphenyl) -3,5-tolylenediamine,
N, N, N ', N'-tetrakis (2,4,6, -trimethylphenyl) -1,3-phenylenediamine, N,
N, N ', N'-tetrakis (2,4,6, -trimethylphenyl) -3,5-tolylenediamine, N, N,
N ', N'-tetrakis (3,5-dimethyl) -1,3
-Phenylenediamine, N, N, N ', N'-tetrakis (3,5-dimethyl) -3,5-tolylenediamine,
N, N, N ', N'-tetrakis (3,5-diethyl)
-1,3-phenylenediamine, N, N, N ', N'-
Tetrakis (3,5-dimethyl) -3,5-tolylenediamine, N, N, N ', N'-tetrakis (3-chlorophenyl) -1,3-phenylenediamine, N, N,
N ', N'-tetrakis (3-bromophenyl) -1,
3-phenylenediamine, N, N, N ', N'-tetrakis (3-iodophenyl) -1,3-phenylenediamine, N, N, N', N'-tetrakis (3-fluorophenyl) -1, 3-phenylenediamine, N, N,
N ', N'-tetrakis (2-tolyl) -1,3-phenylenediamine, N, N, N', N'-tetrakis (2
-Methoxyphenyl) -5-methyl-1,3-phenylenediamine, N, N, N ', N'-tetrakis (2-chlorophenyl) -1,3-phenylenediamine, N,
N, N ', N'-tetrakis (2-aminophenyl)-
5-methyl-1,3-phenylenediamine, N, N,
N ', N'-tetrakis (3-tolyl) -5-methyl-
1,3-phenylenediamine, N, N, N ', N'-hexakis (4-tolyl) -1,3,5-benzenetriamine, N, N, N', N'-tetrakis (3-tolyl) -5-methoxy-1,3-phenylenediamine,
N, N, N ', N'-tetrakis (3-tolyl) -1,
3,5, -Benzenetriamine, N, N, N ', N'-
Tetrakis (3-tolyl) -5-allyl-1,3-phenylenediamine, N, N, N ′, N′-tetrakis (3
-Tolyl) -5-phenyl-1,3-phenylenediamine, N, N, N ', N'-tetrakis (3-tolyl)-
5-chloro-1,3-phenylenediamine, N, N,
N ', N'-tetrakis (3-tolyl) -5-nitro-
1,3-phenylenediamine, N, N, N ′, N′-tetrakis (3-tolyl) -5-sulfo-1,3-phenylenediamine, N, N, N ′, N′-tetrakis (3-
Tolyl) -5-cyano-1,3-phenylenediamine,
N, N, N ', N'-tetrakis (3-tolyl) -5-
Formyl-1,3-phenylenediamine, N, N,
N ', N'-tetrakis (3-tolyl) -5-acetyl-1,3-phenylenediamine, N, N, N', N'-
Tetrakis (3-tolyl) -5-carboxy-1,3-
Phenylenediamine, N, N, N ', N'-tetrakis (3-tolyl) -5-ethoxycarbonyl-1,3-phenylenediamine, N, N'-bis (3-tolyl)-
N, N'-bis (2,4,6, -trimethylphenyl)
-1,3-phenylenediamine.

As the binder resin contained in the above-mentioned organic photosensitive layer, all those which have been conventionally used in the photosensitive material coating liquid can be used, and examples thereof include thermosetting silicone resin, epoxy resin, urethane resin and cured resin. Acrylic resin, acrylic modified urethane resin, alkyd resin, unsaturated polyester resin, diallyl phthalate resin, phenol resin, urea resin, benzoguanamine resin, melamine resin,
Olefinic polymers such as styrene polymers, acrylic polymers, styrene-acrylic polymers, polyethylene, ethylene-vinyl acetate polymers, chlorinated polyethylene, polypropylene, ionomers; polyvinyl chloride; vinyl chloride-vinyl acetate copolymer Polyvinyl acetate; Saturated polyester; Polyamide; Thermoplastic urethane resin; Polycarbonate of bisphenol A type, bisphenol Z type, etc .; Polyarylate; Polysulfone; Ketone resin; Polyvinyl butyral resin; Polyether resin, Polyvinylcarbazole, etc. When the organic photosensitive layer is formed of a plurality of layers, the binder resin can be used to form each layer.

When the organic photosensitive layer is formed of a single layer, the thickness of the organic photosensitive layer is preferably 5 to 100 μm, more preferably 10 to 50 μm.

When the organic photosensitive layer is formed of a single layer, the bisazo compound represented by the general formula (I) is in the range of 0.1 to 15 parts by weight based on 100 parts by weight of the binder resin of the organic photosensitive layer. It is preferable that the content is 0.5%, more preferably 0.5.
10 to 10 parts by weight. When the content of the bisazo compound is less than 0.1 parts by weight, the sensitivity of the photoconductor is lowered. On the contrary, when the content of the bisazo compound exceeds 15 parts by weight, the abrasion resistance of the electrophotographic photosensitive member may decrease.

When the organic photosensitive layer is composed of the charge generation layer and the charge transport layer, the thickness of the charge generation layer is 0.01 to 3.
μm is preferable, and 0.1 to 2 μm is more preferable. The thickness of the charge transport layer is preferably 2 to 100 μm, more preferably 5 to 30 μm.

When the organic photosensitive layer is composed of a charge generation layer and a charge transport layer, the bisazo compound represented by the general formula (I) is 20 to 500 relative to 100 parts by weight of the binder resin of the charge generation layer. It is preferably contained in the range of parts by weight,
It is more preferably 50 to 300 parts by weight. When the content of the bisazo compound is less than 20 parts by weight, the charge generation ability is small, and conversely, the content of the bisazo compound is 500.
When it exceeds the weight part, the mechanical strength of the organic photosensitive layer may decrease.

The organic photosensitive layer may contain various additives such as an antioxidant and a quencher.

The conductive substrate used in the present invention is formed in an appropriate shape such as a sheet shape or a drum shape according to the mechanism and structure of the image forming apparatus in which the electrophotographic photosensitive member is incorporated. The conductive substrate may be entirely formed of a conductive material such as metal, or the base material may be formed of a material having no conductivity and the surface thereof may be provided with a material having conductivity. Good. As the conductive material, for example, the surface is alumite-treated, or untreated aluminum,
Examples include copper, tin, platinum, gold, silver, vanadium, molybdenum, chromium, cadmium, titanium, nickel, palladium, indium, stainless steel, brass, etc. Especially, anodic oxidation by sulfuric acid alumite method and sealing with nickel acetate. Treated aluminum is preferably used. In the case of a conductive substrate formed by providing a conductive material on the surface of a base material made of a material having no conductivity, on the surface of a synthetic resin base material or a glass base material, the above-mentioned metal or A thin film made of a conductive material such as aluminum iodide, tin oxide, or indium oxide formed by a known film forming method such as a vacuum deposition method or a wet plating method, or a film of the metal material or the like on the surface of the base material. It is possible to employ, for example, a laminate of the above, a substrate in which a substance that imparts conductivity is injected into the surface of the base material, or the like. The conductive base material may be subjected to a surface treatment with a surface treatment agent such as a silane coupling agent or a titanium coupling agent, if necessary, to enhance the adhesiveness with the organic photosensitive layer.

The electrophotographic photoreceptor of the present invention is spray-coated with a coating solution prepared by dispersing at least a binder resin and the bisazo compound represented by the general formula (I) in tetrahydrofuran or the like as a solvent or a dispersion medium. Method, dipping method, flow coating method or the like to form an organic photosensitive layer by coating on a conductive substrate. It is preferable to perform heat treatment in order to reduce the amount of tetrahydrofuran remaining in the organic photosensitive layer. For example, it is preferable to heat-treat the conductive substrate coated with the coating liquid at a temperature of 120 ° C. or higher for 30 minutes or longer. .. When the heat treatment temperature is lower than the above conditions, the residual amount of tetrahydrofuran may not be sufficiently reduced.

As the solvent or dispersion medium used in the coating liquid, other solvent or dispersion medium may be used alone or in combination with tetrahydrofuran in addition to tetrahydrofuran.

Examples of such a solvent or dispersion medium include the following. Aliphatic hydrocarbons such as n-hexane, octane and cyclohexane; aromatic hydrocarbons such as benzene, xylene and toluene; halogenated hydrocarbons such as dichloromethane, carbon tetrachloride, chlorobenzene and methylene chloride; methyl alcohol, ethyl alcohol, isopropyl Alcohols such as alcohol, allyl alcohol, cyclopentanol, benzyl alcohol, furfuryl alcohol, diacetone alcohol; ethers such as dimethyl ether, diethyl ether, ethylene glycol dimethyl ether, ethylene glycol diethyl ether; acetone, methyl ethyl ketone, methyl isobutyl ketone, Ketones such as cyclohexanone; esters such as ethyl acetate and methyl acetate; dimethylformamide; dimethylsulfoxide and the like.

The coating liquid is a conventionally known method, for example, a mixer, a ball mill, a paint shaker, a sand mill,
It can be prepared using an attritor, an ultrasonic disperser or the like. When preparing the above coating liquid, a surfactant, a leveling agent or the like may be added in order to improve dispersibility, coatability and the like.

[0044]

The bisazo compound represented by the general formula (I) is one in which the N atom of the pyrrolopyrrole skeleton is azotized through an ethylene chain and a coupler is bonded to the azo compound. In such a structure, the spectral sensitivity can be easily changed and the spectral characteristics can be easily controlled by changing the electron density of N atom by the coupler.

[0045]

EXAMPLES Next, the present invention will be described with reference to Examples and Comparative Examples.

Examples 1 to 7 and Comparative Examples 1 and 2 In order to examine the electrophotographic characteristics of the compounds shown in Table 7 and the following formula, a Transjet photoconductivity measuring method (ZDPopv) was used.
ic, J. Appl. Phys., 52, 6197 (1981)) was used to measure the charge generation efficiency.

[0047]

[Chemical 4]

[0048]

[Chemical 5]

Preparation of Measurement Sample As shown in FIG.
O (indium tin oxide) is vapor-deposited to form the electrode layer 2. A pigment / resin dispersion layer 3 having a thickness of 5 μm is formed on the electrode layer 2.
To form. Gold deposition is performed on this pigment / resin dispersion layer 3,
A measurement sample is obtained by forming the counter electrode 4.

The coating liquid for the pigment / resin dispersion layer was prepared by dispersing the following composition in toluene.

Polyester resin 90% by weight Charge generation material 10% by weight.

Pulse light was applied to the transparent sheet 1 shown in FIG. 1 by using a laser as a light source for exciting a measurement sample of the charge generating material . The voltage drop amount of the pigment / resin dispersion layer 3 sandwiched between the ITO electrode 2 and the gold electrode 4 was measured by this light irradiation. In this measurement, the amount of displacement from the parallel state was measured using the bridge circuit shown in FIG. 1 and 2, 5 is a storage scope, 6 is an electrode, and 7 is a monitor.

The charge generation efficiency η was calculated from the voltage drop amount ΔV as follows.

Η = (C · ΔV / eNφ) · (1 / fv · f (ε ₁ , ε ₂ )) However, the correction function f (ε ₁ , ε ₂ ) can be calculated by the following equation.

F (ε ₁ , ε ₂ ) = ε ₂ / [ε ₁ + 2ε ₂ −fv · (ε ₁ −ε ₂ )] C: capacitance of the sample e: elementary charge Nφ: number of absorbed photons fv : Volume fraction of pigment ε ₁ : Dielectric constant of pigment ε ₂ : Dielectric constant of resin.

In the above equation, the dielectric constant of the bisazo pigment is
Since there are few structural differences, ε ₁ = 4.45, and the dielectric constant of the polyester resin is ε ₂ = 2.60. Further, when the content of the pigment is 10% by weight, fv = 7.25. The sample has a dielectric constant of 2.71 and C = 4.8 at this time.
It is × 10 ^-10 . The number of incident photons is Nφ = 5 × 10
^-10 , and the electric field strength between both electrodes was 3 × 10 ⁷ V / m.
Table 7 shows the voltage drop ΔV and charge generation efficiency of each sample at this time.
Shown in.

Examples 8 to 14 and Comparative Examples 3 to 4 Preparation of Single-Layer Electrophotographic Photosensitive Member 8 parts by weight of the compound shown in Table 8 as a charge generating material, and 3,3'-dimethyl-N as a charge transporting material. , N, N ',
N'-tetrakis-4-methylphenyl- (1,1'-
100 parts by weight of bisphenyl) -4,4'-diamine and 100 parts by weight of polyester as a binder resin were added to a predetermined amount of tetrahydrofuran and mixed and dispersed by a ball mill to prepare a coating solution for a single-layer type photosensitive layer. After applying this coating solution on an aluminum tube, it should be done in the dark at 100 ° C for 3
By drying for 0 minutes, a single-layer type electrophotographic photosensitive member having a photosensitive layer having a thickness of 24 μm was prepared.

Preparation of Laminated Electrophotographic Photoreceptor As a binder resin, 100 parts by weight of polyvinyl butyral,
As a charge generating material, 100 parts by weight of the compound shown in Table 8 and a predetermined amount of tetrahydrofuran were charged in a ball mill,
A charge generation layer coating solution is prepared by stirring and mixing for 24 hours, and the prepared solution is applied onto an aluminum base tube by a dipping method and dried by hot air at 110 ° C. for 30 minutes to be cured to form a film having a thickness of 0.5 μm. A charge generation layer was formed.

Next, 100 parts by weight of a polycarbonate resin as a binder resin and 3,3'- as a charge transport material.
Dimethyl-N, N, N ', N'-tetrakis-4-methylphenyl- (1,1'-bisphenyl) -4,4'-
100 parts by weight of diamine and a predetermined amount of toluene are mixed by stirring with a homomixer to prepare a charge transport layer coating solution, and the prepared solution is coated on the above charge generating layer by a dipping method and heated with hot air at 90 ° C. for 30 minutes. Film thickness 20 by drying
A charge transport layer having a thickness of μm was formed to prepare an electrophotographic photoreceptor.

The initial surface potential Vsp, the half-exposure amount E1 / 2, the residual potential Vrp, and the repeating characteristic Δsp of the single-layer type and laminated type electrophotographic photoreceptors obtained in Examples 8 to 14 and Comparative Examples 3 to 4 were measured. It was measured. The results are shown in Table 8.

1) Measurement of initial surface potential Vsp Each electrophotographic photosensitive member was charged in an electrostatic copying tester (Gentec Cynthia 30M, manufactured by Gentech Co., Ltd.), and the surface thereof was charged positively or negatively to obtain each photosensitivity. Body surface potential Vsp
(V) was measured.

2) Measurement of half-exposure amount E1 / 2 and residual potential Vrp Each electrophotographic photosensitive member in the above charged state was exposed at an exposure intensity of 10 lux using a halogen lamp which is an exposure light source of the above electrostatic copying test apparatus. Then, the time until the surface potential Vsp becomes 1/2 is determined, and the half-exposure amount E1 / 2 (lux · se
c) was calculated. The surface potential after 0.15 seconds has elapsed from the start of the exposure is defined as the residual potential Vrp (V).

[0063]

[Table 7]

[0064]

[Table 8]

From Tables 7 and 8, the charge generation materials of Examples are as follows:
It can be seen that the charge generation efficiency is excellent, and the single-layer type and multi-layer type electrophotographic photoconductors have high sensitivity and excellent repeating characteristics.

[0066]

As is clear from the above description, according to the electrophotographic photoreceptor of the present invention, it is possible to provide an electrophotographic photoreceptor having high sensitivity in the visible light region and excellent in repeating characteristics. ..

[Brief description of drawings]

FIG. 1 is a circuit diagram for measuring a voltage drop amount of a measurement sample in Examples 1 to 7 and Comparative Examples 1 and 2.

FIG. 2 is a bridge circuit used for measuring a voltage drop amount of a measurement sample.

[Explanation of symbols]

 1 polypropylene sheet 2 electrode layer 3 pigment / resin dispersion layer 4 counter electrode 5 storage scope 6 power supply 7 monitor

Claims (1)

[Claims] 1. An electrophotographic photoreceptor having an organic photosensitive layer provided on a conductive substrate, wherein the organic photosensitive layer contains a bisazo compound represented by the following general formula (I) as a charge generating material. An electrophotographic photosensitive member. [Chemical 1] (In the formula, R ¹ and R ² each independently represent an oxygen atom or a sulfur atom, R ³ and R ⁴ each independently represent a hydrogen atom, an alkyl group or an aryl group, and m and n are Each independently represents an integer of 0 to 2, Cp
¹ and Cp ² each independently represent a coupler residue. )