JP2000199978A - Electrophotographic photoreceptor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an electrophotographic photoreceptor which is superior in optical fatigue characteristics. SOLUTION: This electrophotographic photoreceptor has a photosensitive layer containing an electronic charge transferring material having either or more π electrons having no aromaticity and a fluorescence yeild Φ of 1>Φ>0.13 in a dilute THF solution, or an electric charge transferring material having twelve or more πelectrons having no aromaticity and a fluorescence yield Φof 1>Φ>0.09 in a dilute THF solution.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic photosensitive member. More specifically, the present invention relates to a high-sensitivity and high-performance electrophotographic photoreceptor having a photosensitive layer containing an organic photoconductive substance, which is particularly excellent in light fatigue characteristics.

[0002]

2. Description of the Related Art In recent years, electrophotographic photoconductors have been developed mainly by so-called function-separated type photoconductors in which charge carrier generation and transfer functions are shared by different compounds.
Practical use of this type of organic photoreceptor has been carried out. As the charge carrier transport medium, there are a case where a polymer photoconductive compound such as polyvinyl carbazole is used and a case where a low molecular weight photoconductive compound is dispersed and dissolved in a binder polymer.

In particular, organic low-molecular-weight photoconductive compounds include:
As a binder, a polymer having excellent film properties, flexibility, adhesiveness and the like can be selected, so that a photoreceptor having excellent mechanical properties can be easily obtained (for example, JP-A-60-196767, JP-A-60-21865
No. 2, JP-A-60-233156, JP-A-60-233156
JP-A-3-48552, JP-A-1-267552, JP-B-3-39306, JP-A-3-1-1134
No. 59, JP-A-1-123358 and JP-A-3
-149560, JP-A-6-273950, JP-A-62-36674, JP-A-7-036
No. 203, JP-A-6-11854, JP-A-6
3-48555, etc.). However, it may be difficult to find a compound suitable for making a highly sensitive photoreceptor.

[0004] Further, in the constant demand for higher sensitivity,
In terms of electrical characteristics, there are various problems such as insufficient residual potential, poor photo-responsibility, deterioration of charging property when used repeatedly, and accumulation of residual potential. A technique of using a combination of hydrazone compounds to prevent a rise in residual potential without significantly impairing other characteristics of the photoreceptor (Japanese Patent Application Laid-Open No. 61-134767) has been reported. However, the specific balance is not always sufficient, and a technique for improving the characteristics of the entire photoreceptor in a well-balanced manner has been required. Furthermore, the photoreceptor is exposed to light by static elimination light and exposure during the process,
Even when the photoconductor is replaced, it is exposed to general indoor light. An electrophotographic photoreceptor with less light fatigue due to such light exposure has also been required at the same time.

[0005]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and the first object of the present invention is to solve the above problems.
An object of the present invention is to provide an electrophotographic photosensitive member having high sensitivity and high mobility. The second purpose is for electrophotography, which has high sensitivity, has a sufficiently low residual potential even when the film thickness is increased, has little variation in characteristics even when used repeatedly, and has extremely excellent light fatigue characteristics. It is to provide a photoreceptor. A third object of the present invention is to provide a balanced electrophotographic photoreceptor that has high sensitivity even at a long wavelength of about 800 nm and has good chargeability, dark decay, and residual potential.

[0006]

Means for Solving the Problems The present inventors have conducted intensive studies on organic low-molecular-weight photoconductive compounds satisfying these objects, and found that compounds satisfying specific parameters are suitable. The present invention has been reached. That is,
The gist of the present invention is to provide an electrophotographic photoreceptor having a photosensitive layer containing a charge generation substance and a charge transport substance, wherein the charge transport substance has eight or more π electrons having no aromaticity, and The fluorescence yield at

[0007]

[Equation 3] 1> Φ> 0.13

An organic charge transport material that satisfies, or the charge transport material has at least 12 non-aromatic π electrons,
And the fluorescence yield Φ in the solution is

[0009]

## EQU4 ## 1> Φ> 0.09

An electrophotographic photoreceptor characterized by containing an organic charge transporting material satisfying the following.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
The present inventors have paid attention to the possibility that the triplet inactivation process may destroy molecules in the organic molecular light fatigue mechanism, and examined the inactivation process after photoexcitation of the charge transport material. . In organic charge transport materials, do not have aromaticity,
In terms of improving double bond introduction, sensitivity, residual potential, mobility, and solubility, it may be an important molecular design.

However, the molecule having this double bond, as represented by a stilbene molecule, does not return to its original state after photoexcitation but passes through a deactivation process through a triplet excited state. It is known that some molecules transfer to various molecules. This triplet excited state is
The excited state has a longer lifetime than the singlet excited state, during which the molecule may be more likely to be destroyed. In addition, this excited state is easily affected by oxygen molecules in the ground triplet,
It is considered fragile. Therefore, a molecule having a high fluorescence yield is directly deactivated from the singlet excited state to the singlet ground state, so that it is difficult to take another deactivation path, and to prevent light fatigue.
Seems strong. Therefore, among charge transporting substances having a large number of double bonds, those that controlled this deactivation process and have a high fluorescence yield were considered to be molecules that are strong against light fatigue, and led to the present invention. . That is, it has eight or more π electrons having no aromaticity, and the fluorescence yield Φ in the solution of the charge transport substance is

[0013]

## EQU5 ## 1> Φ> 0.13

The organic charge transporting material satisfying the above conditions, or the charge transporting material has 12 or more non-aromatic π electrons, and the fluorescence yield Φ of the charge transporting material in a solution is

[0015]

1> Φ> 0.09

A photoreceptor containing an organic charge transport material satisfying the above conditions satisfies the above conditions, and is an electrophotographic photoreceptor excellent in chargeability, sensitivity, residual potential and the like, and also excellent in light fatigue. Examples of the compound satisfying the above conditions include the compounds of the following structural formulas (1) and (2), but the present invention is not limited to these.

[0017]

Embedded image

The fluorescence yield Φ of the charge transport material is
In (tetrahydrofuran) solution (concentration 1-5 × 10 ^-6 m
ol / L) by a conventional method. When a compound satisfying the parameters of the present invention is used as a charge transporting substance, a photosensitive member having high sensitivity and excellent durability can be obtained. As a form of the photosensitive layer of the electrophotographic photosensitive member,
Various types are known, and any of the photosensitive layers of the electrophotographic photosensitive member of the present invention may be used.

The photosensitive layer (photoconductive layer) is formed by laminating a charge generating layer and a charge transporting layer in this order, or by laminating the charge generating layer and the charge transporting layer in reverse order. Any configuration such as a so-called dispersion type in which particles of the (generating substance) are dispersed can be used. For example, a single-layer photosensitive layer in which an organic charge transporting substance is added to a binder, and a dye or an electron-withdrawing compound as a sensitizer, if necessary, a charge generating material that generates charge carriers with extremely high efficiency when absorbing light (Photoconductive particles), a dispersion-type photosensitive layer in which an organic charge transport material is dispersed in a binder,
Examples of the charge generating layer include a charge generating layer composed of an organic charge transporting material and a binder and a charge generating material that generates charge carriers with extremely high efficiency when absorbing light, or a laminated photosensitive layer in which a charge generating layer composed of the charge generating layer and a binder is laminated.

In these photosensitive layers, other known arylamine compounds and hydrazone compounds having excellent performance as an organic photoconductor together with the organic charge transporting material of the present invention,
A stilbene compound may be mixed. In the present invention, when the organic charge transporting material of the present invention is used in a charge transport layer of a photosensitive layer composed of a charge generation layer and a charge transport layer (charge transfer layer), the sensitivity is particularly high and the residual potential is low. small,
In addition, a photosensitive member having excellent durability can be obtained.

Specifically, usually, a charge generation material is directly deposited or coated as a dispersion with a binder to form a charge generation layer, and an organic solvent solution containing the organic charge transport material is cast on the charge generation layer. Alternatively, it can be obtained by dissolving the organic charge transporting substance together with a binder or the like, and applying a dispersion thereof. Further, the charge generating substance and the charge transporting substance may be dispersed and dissolved in a binder to form a single-layer photosensitive member coated on a conductive support. Hereinafter, a configuration usually used in the electrophotographic photoreceptor of the present invention will be described.

As the conductive support on which the photosensitive layer is formed, any of those used for known electrophotographic photosensitive members can be used. Specifically, for example, aluminum, stainless steel, copper, a drum made of a metal material such as nickel, a laminate of these metal foils, a deposited material, or a surface of aluminum, copper, palladium, tin oxide, indium oxide or the like Examples include an insulating support such as a polyester film or paper provided with a conductive layer. Furthermore, a conductive film such as a metal powder, carbon black, copper iodide, and a polymer electrolyte coated with an appropriate binder and subjected to conductive treatment, a plastic drum,
Paper, paper tube, and the like are included. Further, a plastic sheet or drum containing a conductive substance such as a metal powder, carbon black, or carbon fiber to become conductive may be used. or,
Plastic films and belts that have been subjected to conductive treatment with a conductive metal oxide such as tin oxide and indium oxide can be used.
Among them, an endless pipe made of metal such as aluminum is a preferable support. A photosensitive layer is formed on the support.

As the charge generating material in the photosensitive layer, inorganic photoconductive particles such as selenium, selenium-tellurium alloy, selenium-arsenic alloy, cadmium sulfide, and amorphous silicon;
Organic photoconductive such as metal-free phthalocyanine, metal-containing phthalocyanine, perinone pigment, thioindigo, quinacridone, perylene pigment, anthraquinone pigment, azo pigment, bisazo pigment, trisazo pigment, tetrakis azo pigment, cyanine pigment, etc. And organic photoconductive particles are preferred.

Further, various organic pigments and dyes such as polycyclic quinone, pyrylium salt, thiopyrylium salt, indigo, anthantrone and pyranthrone can be used. Among them, metal-free phthalocyanine, copper, indium chloride, gallium chloride,
Metals such as tin, oxytitanium, zinc, vanadium or oxides thereof, phthalocyanines coordinated with chlorides,
Azo pigments such as monoazo, bisazo, trisazo, and polyazos are preferred.

Among them, a metal-containing phthalocyanine or a metal-free phthalocyanine is preferable, and the Bragg angle (2θ ± 0.2 °) of the X-ray diffraction pattern by Cu-Kα ray is 9.7.
Oxytitanium phthalocyanine showing diffraction peaks at °, 24.2 ° and 27.3 ° is particularly preferred. The method for producing the oxytitanium phthalocyanine is not particularly limited, but is produced, for example, by the following method.

1. A method for producing type [II] crystals described in Production Example 1 of JP-A-62-67094. That is, orthophthalodinitrile and a halide of titanium are heated and reacted in an inert organic solvent, and then hydrolyzed. 2. Various crystal forms of oxytitanium phthalocyanine are directly converted to sulfuric acid or a compound of the formula R—SO ₃ H (wherein R
Represents an aliphatic or aromatic residue which may have a substituent. ) Or heat treatment with a mixed solvent of an insoluble organic solvent and water. 3. If desired, previously dissolved in concentrated sulfuric acid and then released into ice water, made amorphous by a known method such as a mechanical grinding method such as a paint shaker, ball mill, sand grind mill, etc., and then heat-treated with the above sulfonated product or water-insoluble. Heat treatment with a mixed solvent of an organic solvent and water. 4. In the case of the above-mentioned treatment with a sulfonated product, it can also be produced by using a mechanical grinding method such as a paint shaker, a ball mill, or a sand grinding mill instead of the heat treatment.

In addition to the above oxytitanium phthalocyanine, a Bragg angle (2θ ± 0.2 °) of 9.3 °,
Oxytitanium phthalocyanine showing diffraction peaks at 3.2 °, 26.2 ° and 27.1 °, Bragg angle (2θ
± 0.2 °) 9.2 °, 14.1 °, 15.3 °, 1
Dihydroxysilicon phthalocyanine showing diffraction peaks at 9.7 ° and 27.1 °, Bragg angle (2θ ± 0.2
°) 8.5 °, 12.2 °, 13.8 °, 16.9 °,
Dichlorotin phthalocyanine, which exhibits diffraction peaks at 22.4 °, 28.4 °, and 30.1 °, is also a preferred charge generating substance, and a mixture of these with the above-mentioned oxytitanium phthalocyanine is also a preferred embodiment.

Next, dyes which are optionally added to the photosensitive layer as a sensitizer include triphenylmethane dyes such as methyl violet, brilliant green and crystal violet, thiazine dyes such as methylene blue, and quinone dyes such as quinizarin. And cyanine dyes, bilirium salts, thiavirylium salts, benzovirylium salts, and the like.

Examples of the electron-withdrawing compound which forms a charge transfer complex with an organic charge transporting substance include, for example, chloranil, 2,3-dichloro-1,4-naphthoquinone, 1-nitroanthraquinone, 1-chloro-5-nitro Quinones such as anthraquinone, 2-chloroanthraquinone and phenanthrenequinone; aldehydes such as 4-nitrobenzaldehyde; 9-benzoylanthracene, indandione, 3,5-dinitrobenzophenone, and 2,4,7-
Ketones such as trinitrofluorenone, 2,4,5,7-tetranitrofluorenone, 3,3 ', 5,5'-tetranitrobenzophenone; acid anhydrides such as phthalic anhydride and 4-chloronaphthalic anhydride; Cyano compounds such as tetracyanoethylene, terephthalalmalononitrile, 9-anthrylmethylidenemalononitrile, 4-nitrobenzalmalonenitrile, 4- (p-nitrobenzoyloxy) benzalmalononitrile; 3-benzalphthalide, 3- (Α-cyano-p-nitrobenzal) phthalide, 3- (α-cyano-p-nitrobenzal) -4,
Electron-withdrawing compounds such as phthalides such as 5,6,7-tetrachlorophthalide;

The charge generation layer in the laminated photosensitive layer is made of fine particles of these substances, for example, polyester resin, polyvinyl acetate, polyester, polycarbonate, polyvinyl acetoacetal, polyvinyl propional,
It is preferable to bind with various binder resins such as polyvinyl butyral, phenoxy resin, epoxy resin, urethane resin, cellulose ester and cellulose ether. Further, examples of the binder resin include polymers and copolymers of vinyl compounds such as styrene, vinyl acetate, vinyl chloride, acrylates, methacrylates, vinyl alcohol, and ethyl vinyl ether, polyamides, and silicon resins. In this case, the use ratio of the charge generating substance is usually 20 to 100 parts by weight of the binder resin.
To 2000 parts by weight, preferably 30 to 500 parts by weight, and the thickness of the charge generation layer is usually 0.05
To 5 μm, preferably 0.1 to 2 μm, more preferably 0.15 to 0.8 μm.

The charge generation layer may contain various additives such as a leveling agent, an antioxidant, and a sensitizer for improving coating properties, if necessary. Alternatively, the charge generation layer may be a deposited film of the above charge generation material. As the binder resin used for the charge transport layer of the laminated photosensitive layer, a resin that has good compatibility with the charge transport material and does not crystallize or phase separate from the charge transport material after forming the layer is used. The binder resin is appropriately selected from the same group as the binder resin used in the charge generation layer. However, in the case of laminating by a coating method, it is necessary to prevent the previously formed layer from being dissolved by the solvent of the coating liquid to be applied later. For this purpose, usually, the binder resin of the previously formed layer is cross-linked and cured, or a solvent that dissolves only one of the binders of the charge generation layer and the charge transport layer is used. The thickness of the charge transport layer of the laminated photosensitive layer is
It is usually from 10 to 50 μm, preferably from 15 to 45 μm, particularly preferably from 25 to 40 μm.

In the case of the dispersion type photosensitive layer, the particle size of the charge generating material must be sufficiently small, and is preferably 1 μm or less, more preferably 0.5 μm or less. The amount of the charge generating material dispersed in the photosensitive layer is, for example, 0.5 to 5
Although it is in the range of 0% by weight, if the amount is too small, sufficient sensitivity cannot be obtained. If the amount is too large, there are adverse effects such as a decrease in chargeability and a decrease in sensitivity. More preferably, it is used in the range of 1 to 20% by weight. .

The binder resin used as the matrix of the dispersion type photosensitive layer is preferably a polymer which has good compatibility with the charge transport material and does not crystallize or phase-separate the charge transport material after forming the coating film. For example, styrene, vinyl acetate, vinyl chloride, acrylate,
Methacrylic acid esters, polymers and copolymers of vinyl compounds such as butadiene, polyvinyl acetal, polycarbonate, polyester, polyester carbonate,
Examples include various polymers such as polysulfone, polyimide, polyphenylene oxide, polyurethane, cellulose ester, cellulose ether, phenoxy resin, silicon resin, and epoxy resin, and partially cross-linked cured products thereof can also be used. The amount of the binder used is usually 0.5 to 30 times by weight, preferably 0.1 to 30 times the weight of the organic charge transporting substance.
The range is 7 to 10 times by weight.

The thickness of the dispersion type photosensitive layer is usually 5 to 50 μm,
More preferably, it is used at 10 to 45 μm. Also in this case, a known plasticizer for improving film formability, flexibility, mechanical strength, etc., an additive for suppressing residual potential, a dispersion aid for improving dispersion stability, and a coating property. Leveling agents and surfactants for improvement, for example, silicone oil, fluorinated oil and other additives may be added. Further, the photosensitive layer of the electrophotographic photosensitive member of the present invention may contain a well-known plasticizer in order to improve film formability, flexibility, and mechanical strength. Examples of the plasticizer include phthalate esters, phosphate esters, epoxy compounds, chlorinated paraffins, chlorinated fatty acid esters, and aromatic compounds such as methylnaphthalene.

The photoreceptor thus formed may also have, if necessary, an improvement in electrical and mechanical properties, such as a barrier layer, an adhesive layer, an intermediate layer such as a blocking layer, a transparent insulating layer, or a protective layer. It is needless to say that a layer may be provided. Barrier layer, as an intermediate layer, for example, aluminum anodized film, aluminum oxide, inorganic layers such as aluminum hydroxide, polyvinyl alcohol, casein, polyvinylpyrrolidone, polyacrylic acid, celluloses, gelatin, starch, polyurethane, polyimide, polyamide, And the like.

Further, as the outermost surface layer, a conventionally known overcoat layer mainly composed of, for example, a thermoplastic or thermosetting polymer may be provided. Usually, the charge transfer layer is formed on the charge generation layer, but the reverse is also possible. As a forming method of each layer, a known method such as sequentially applying a coating solution obtained by dissolving or dispersing a substance to be contained in a layer in a solvent can be applied. In addition to the above, various additives for improving the mechanical strength and durability of the coating film can be used in the charge transport layer.

Examples of such additives include well-known plasticizers, various stabilizers, flowability-imparting agents, and crosslinking agents. Examples of the method for coating the photosensitive layer include a spray coating method, a spiral coating method, a ring coating method, and a dip coating method. Spray coating methods include air spray, airless spray, electrostatic air spray, electrostatic airless spray, rotary atomizing electrostatic spray, hot spray, hot airless spray, etc., but fine particles to obtain a uniform film thickness Degree,
Considering the adhesion efficiency and the like, in a rotary atomizing electrostatic spray, the transfer method disclosed in Japanese Patent Laid-Open Publication No. 1-805198, that is, continuous rotation of a cylindrical work without rotating an axial direction while rotating the work. By conveying the photosensitive member, it is possible to obtain an electrophotographic photosensitive member having high overall deposition efficiency and excellent film thickness uniformity.

As the spiral coating method, Japanese Patent Application Laid-Open No.
A method using a liquid coating machine or a curtain coating machine disclosed in Japanese Patent Application Laid-Open No. 119651, a method for continuously flying paint in a streak shape from a fine opening disclosed in Japanese Patent Application Laid-Open No. 1-231966, There is a method using a multi-nozzle body disclosed in Japanese Unexamined Patent Publication No. 3-193161.
Hereinafter, the most widely used dip coating method will be specifically described. Using the above-described organic charge transporting material, binder, solvent and the like of the present invention, a suitable total solid content concentration is 25% or more, more preferably 40% or less, and a viscosity is usually 50 to 300 centipoise or less, preferably 100
A coating liquid for forming a charge transporting layer having a thickness of 200 centipoise or less is prepared. Here, the viscosity of the coating solution is substantially determined by the type and molecular weight of the binder polymer. However, if the molecular weight is too low, the mechanical strength of the polymer itself is reduced, so that the binder polymer has a molecular weight that does not impair the mechanical strength. It is preferred to use The charge transport layer is formed by a dip coating method using the coating solution thus adjusted.

Solvents for preparing a coating solution include ethers such as tetrahydrofuran and 1,4-dioxane; ketones such as methyl ethyl ketone and cyclohexanone; aromatic hydrocarbons such as toluene and xylene; N, N-dimethylformamide, acetonitrile , N-methylpyrrolidone,
Aprotic polar solvents such as dimethyl sulfoxide; esters such as ethyl acetate, methyl formate, and methyl cellosolve acetate; solvents that dissolve organic charge transporting substances such as chlorinated hydrocarbons such as dichloroethane and chloroform. Of course, it is necessary to select a material that dissolves the binder from these. Thereafter, the coating film is dried, and the drying temperature and time may be adjusted so that necessary and sufficient drying is performed. The drying temperature is usually 100 to 250 ° C, preferably
110-170 ° C, more preferably 120-140 ° C
Range. As a drying method, a hot air dryer, a steam dryer, an infrared dryer, a far infrared dryer, or the like can be used.

[0040]

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

Example 1 In the X-ray diffraction pattern by Cu-Kα ray, Bragg angle (2θ ± 0.2 °) 9.
3 °, 10.6 °, 13.2 °, 15.1 °, 15.7
°, 16.1 °, 20.8 °, 23.3 °, 27.1 °
After adding 1.0 part of titanium oxyphthalocyanine pigment showing a diffraction peak to 14 parts of dimethoxyethane and dispersing with a sand grinder, dimethoxyethane 14
And 14 parts of 4-methoxy-4-methylpentanone-2 (manufactured by Mitsubishi Chemical Corporation) were added and diluted, and then polyvinyl butyral (Denka Butyral # 6000-, manufactured by Denki Kagaku Kogyo Co., Ltd.) C) 0.5 part and phenoxy resin (manufactured by Union Carbide Co., Ltd., trade name UCAR)
(Trademark registered) PKHH) 0.5 part with dimethoxyethane 6
And 4-methoxy-4-methylpentanone-26 in a mixed solution to obtain a dispersion. 75μ
The weight of this dispersion after drying was 0.4 g on an aluminum vapor-deposited layer vapor-deposited on a polyester film having a thickness of m.
/ M ² , and then dried to form a charge generation layer. On top of this, the compound (1) 7
0 parts and polycarbonate resin shown below

[0042]

Embedded image

A coating solution obtained by dissolving 100 parts in a mixed solvent of 900 parts of tetrahydrofuran was applied, dried, and dried.
A μm charge transport layer was formed. 2 obtained in this way
When the sensitivity, that is, the half-life exposure amount was measured by an electrophotographic photosensitive member having a photosensitive layer composed of
m ² . First, the half-exposure amount is set at 50
780 n obtained by negatively charging with a corona current of μA and then passing 20 lux white light through an interference filter
m (light exposure energy: 10 μW / cm ² )
It was determined by measuring the exposure required for the surface potential to attenuate from -550 V to -275 V.

Further, when the surface potential when the exposure time was 9.9 seconds was measured as a residual potential, it was -9 V. This operation was repeated 2000 times, but no increase in the residual potential was observed. The surface potential when the photoreceptor was negatively charged by a corona current of 50 μA in a dark place was defined as V ₀ , and the photoreceptor was irradiated with 3000 lux white light for 5 minutes and then similarly negatively charged. Let the surface potential be V,
When (V / V ₀ ) was obtained as a strong exposure holding ratio, 9
It was 1.4%.

Further, the process of negative charge-exposure
The surface potential when negatively charged after the repetition was defined as V ′, and (V ′ / V ₀ ) was determined as the strong exposure return rate, which was 92.6%. Further, the fluorescence yield (irradiation UV: 254 nm) of the compound (1) in a dilute THF solution was 0.164.

Example 2 An electrophotographic photosensitive member was obtained in the same manner as in Example 1 except that 50 parts of the compound (2) was used instead of the arylamine-based compound used in Example 1. Next, the sensitivity, residual potential, strong exposure holding ratio, strong exposure return ratio, and fluorescence yield were measured in the same manner as in Example 1. The results are shown in Table 1 together with the measurement results for the photoconductor of Example 1.

(Comparative Example 1) Instead of the arylamine compound used in Example 1, the following comparative compound (3)
An electrophotographic photoreceptor was obtained in the same manner as in Example 1 except for using.

[0048]

Embedded image

Next, in the same manner as in Example 1, the sensitivity, residual potential, strong exposure holding ratio, strong exposure return ratio, and fluorescence yield were measured. The results are shown in Table 1 together with the measurement results for the photoconductor of Example 1.

[0050]

[Table 1]

[0051]

The photoreceptor for electrophotography of the present invention has a low residual potential which causes fogging, and in particular, has little light fatigue, so that the residual potential accumulates due to repeated use, and the fluctuation of the surface potential and sensitivity is small and the durability is small. It has the feature of being excellent in properties.

Claims (4)

[Claims] 1. An electrophotographic photosensitive member having a photosensitive layer containing a charge generating material and a charge transporting material on a conductive support, wherein the charge transporting material has eight or more non-aromatic π electrons. And an organic charge transport material having a fluorescence yield Φ of the charge transport material in a diluted THF solution that satisfies the following expression: 1>Φ> 0.13. 2. An electrophotographic photosensitive member having a photosensitive layer containing a charge generating substance and a charge transporting substance on a conductive support, wherein the charge transporting substance has 12 or more π electrons having no aromaticity. And an organic charge transport material having a fluorescence yield Φ of the charge transport material in a diluted THF solution that satisfies the following expression: 1>Φ> 0.09. 3. The electrophotographic photoconductor according to claim 1, wherein the charge transporting substance has at least two alkyl groups. 4. The electrophotographic photoreceptor according to claim 1, wherein the charge generating substance is a metal-free phthalocyanine, a metal phthalocyanine, or a bisazo pigment.