JPH10301306A - Electrophotographic photoreceptor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an electrophotographic photoreceptor showing excellent charge holding rate, sensitivity, residual potential, etc., which can be electrified into both of positive and negative charges. SOLUTION: This electrophotographic photoreceptor has a photosensitive layer on a conductive supporting body. The photosensitive layer contains a methylidene hydrazonofluorene deriv. expressed by the formula. In the formula, R<1> , R<2> are independently alkyl groups, aryl groups, aralkyl groups, heterocyclic groups which may have substituents, or R<1> and R<2> may form a ring, and n is a number 1 to 4.

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 containing a compound having an electron transporting ability in a photosensitive layer.

[0002]

2. Description of the Related Art In recent years, as a material for an electrophotographic photosensitive member,
Various organic compounds have been researched and developed in place of inorganic photoconductors such as selenium and zinc oxide, and some of them have been put to practical use. These organic photoreceptor materials can be broadly classified into “charge generation materials” that mainly generate charges and “charge transport materials” that transport charges. Further, the charge transporting material is classified into a charge transporting material having a hole transporting ability (hereinafter, referred to as a hole transporting material) and a charge transporting material having an electron transporting ability (hereinafter, referred to as an electron transporting material).

[0003] Most of organic photoreceptors put into practical use use a hole transporting material such as a pyrazoline compound, a hydrazone compound or a triarylamine compound as a charge transporting material. When a hole transporting material is used as the charge transporting material, from the viewpoint of sensitivity, durability, etc.,
In general, a charge generation layer and a charge transport layer are laminated on a substrate in this order. In this case, the charging of the photoconductor must be negative. However, in charging by corona discharge, ozone generated at the time of negative charging poses a problem as deterioration of the photoconductor and environmental pollution. In order to solve these problems, it is necessary to take special measures such as a charging system that does not generate ozone, a system that decomposes or adsorbs generated ozone, and a system that exhausts ozone in the device. There is a drawback that it is complicated and leads to an increase in cost.

On the other hand, when an electron transporting material is used as a charge transporting material, positive charging can be performed in the above-described photoconductor. Generally, in charging by corona discharge, the amount of generated ozone is smaller in positive charging than in negative charging, uniform and stable charging can be performed, and the obtained electrophotographic image has higher stability. It is also possible to design a photoreceptor capable of both positive and negative charging by appropriately combining a hole transporting material and an electron transporting material as necessary.

[0005] From such a viewpoint, the appearance of a high-performance electron transport material has been desired. However, there have been few effective materials for the electron transport material and various problems have been encountered. For example, 2,4,7-trinitro- as disclosed in U.S. Pat.
9-Fluorenone (TNF) has low solubility and compatibility with solvents and binders, making it difficult to form a practical photoreceptor. Furthermore, TNF is known to have carcinogenic properties, and it is difficult to use it from this point as well.

In recent years, several new electron transporting materials such as quinone compounds, thiopyran compounds and tetracarboxylic diimide compounds have been proposed. For example, JP 1-20
No. 6349 describes a compound having a diphenoquinone structure. Further, there are JP-A-9-40672 using a tryptoanthrin compound and JP-A-9-12555 using an azafluorene compound.

[0007]

However, these electron transporting materials do not always have sufficient performance in sensitivity, potential holding property, potential stability, residual potential and the like. SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an electrophotographic photosensitive member having excellent electrophotographic characteristics and capable of both positive and negative charging.

[0008]

Means for Solving the Problems The present inventors have conducted intensive studies in order to solve the above-mentioned problems, and as a result, it has been found that the use of a methylidenehydrazonofluorene derivative having a specific chemical structure as an electron transporting material has resulted in an excellent effect. It has been found that an electrophotographic body can be obtained.

That is, an object of the present invention is to provide the following electrophotographic photosensitive member in order to solve the above-mentioned problems.

In an electrophotographic photosensitive member having a photosensitive layer on a conductive support, the photosensitive layer contains a methylidenehydrazonofluorene derivative represented by the general formula [1]. Photoconductor.

[0011]

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(In the formula, R ¹ and R ² each independently represent an alkyl group, an aryl group, an aralkyl group, or a heterocyclic group which may have a substituent. R ¹ and R ^{2 each} represent a ring. May be formed. N represents a number of 1 to 4.)

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, any of the methylidenehydrazonofluorene derivatives represented by the general formula [1] (hereinafter, referred to as methylidenehydrazonofluorene derivatives) can be used. The substituents R ¹ and R ² of the methylidenehydrazonofluorene derivative used in the present invention include, for example, an alkyl group such as a methyl group, an ethyl group, an n-propyl group, a sec-propyl group and an n-butyl group; Groups, aryl groups such as anthranyl groups, aralkyl groups such as benzyl groups, and heterocyclic groups such as furan rings and indole rings.

The substituents that R ¹ and R ² may have include halogen atoms such as a fluorine atom, a chlorine atom and a bromine atom, a methyl group, an ethyl group, an n-propyl group, a sec-propyl group, Alkyl groups such as n-butyl group, hydroxy group, methoxy group, alkoxy group such as ethoxy group, amino group, diethylamino group, substituted amino group such as diphenylamino group, carboxyl group, ester group, amide group, sulfonic acid group,
Examples include a nitro group, a cyano group, and a dicyanomethylene group. R ¹ and R ² are, for example, 1-indanilidene group, 9-
A ring may be formed like a fluorenylidene group.

These compounds can be produced by a known method. Examples of the production method include a reaction of a fluorene compound, a hydrazine compound, and a ketone compound. As a typical example, for example, in the first stage, a fluorene compound is reacted with a hydrazine compound to generate a hydrazone compound, and in the second stage, the hydrazone compound is reacted with a ketone compound, and A method for obtaining a lidenehydrazonofluorene derivative, in the first step, a ketone compound is reacted with a hydrazine compound to generate a hydrazone compound, and in the second step, the hydrazone compound is reacted with the fluorene compound,
A method of obtaining the methylidenehydrazonofluorene derivative, and the like.

The reaction conditions in each of the above steps may be appropriately selected so as to obtain a higher yield with less by-products. Usually, however, no solvent or a solvent which does not react with a raw material which simultaneously dissolves both is used. And the molar ratio of both is 0.8 / 1.0 to 1.
0 / 0.8, preferably equimolar ratio, at a reaction temperature of 10 ° C.
The reaction is performed at a reflux temperature for a period of one week to 30 minutes.

In each stage, a catalyst can be used if necessary, but a catalyst capable of making the reaction system acidic is preferable.
Typically, acids such as acetic acid, hydrochloric acid and the like can be mentioned. As the reaction solvent, for example, toluene, benzene and the like can be used. A catalyst that is liquid at room temperature is convenient because it can be used as a solvent.

The crude product obtained by the reaction is preferably purified by, for example, recrystallization or column chromatography to obtain a higher purity before use.

More specifically, for example, the exemplified compound (7) can be synthesized as follows.

That is, 2,7-dinitrofluorenone (2.70
g) and hydrazine monohydrate (1.0 ml) in acetic acid (50 ml) in 80
The reaction was carried out at 8585 ° C. for 5 hours to obtain 2,7-dinitro-9-hydrazonofluorene (1.95 g). This and 4′-diethylaminoacetophenone (1.91 g) were allowed to stand at 160 ° C. without solvent for 30 minutes,
The obtained crude product was purified by column chromatography (methylene chloride) to give Exemplified Compound (7) (1.01 g).

Next, specific examples of the methylidenehydrazonofluorene derivative used in the present invention are shown below, but the present invention is not necessarily limited to these examples.

[0022]

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[0023]

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[0024]

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The electrophotographic photoreceptor of the present invention comprises a photosensitive layer containing a methylidenehydrazonofluorene derivative formed on a conductive support. The present invention can be used for either a single-layer type photoreceptor existing in the same layer or a laminated type photoreceptor in which the charge generating material and the charge transporting material are present in different layers.

The single-layer type photoreceptor is prepared by applying a coating solution obtained by dispersing or dissolving a charge generation material, a hole transporting material and an electron transporting material in a binder resin solution on a conductive support and drying the photosensitive layer. It can be manufactured by forming.

On the other hand, a laminate type photoreceptor is a dispersion obtained by depositing a charge generating material on a conductive support or dispersing fine particles of the charge generating material in a solvent in which a binder resin is dissolved if necessary. Is applied and dried, and then a coating solution in which an electron transport material is dissolved in a binder resin solution is applied thereon to form a charge transport layer. Conversely, the charge transport layer may be formed first on the conductive support, and then the charge generation layer may be formed.

Further, these electrophotographic photoreceptors are intended to protect the conductive support, improve adhesion, improve coating properties, control the amount of charge injected from the conductive support into the photosensitive layer, and the like. Alternatively, an intermediate layer may be provided between the conductive support and the photosensitive layer. Further, in order to protect the photoreceptor from physical or chemical external factors, a surface protective layer may be further provided on the surface of the photosensitive layer.

Examples of the conductive support used in the electrophotographic photoreceptor of the present invention include: 1) aluminum, copper,
Metals or alloys such as zinc, stainless steel, chromium, titanium, nickel, molybdenum, vanadium, indium, gold and platinum; 2) conductive compounds such as conductive polymers, indium oxide and tin oxide; or 3) aluminum and palladium , Rhodium, gold, platinum or other metal or alloy, coating, vapor deposition, lamination, etc.
Examples include plastic films and ceramics.
Further, the surface of the conductive support may be subjected to a chemical or physical treatment as necessary.

Although the shape of the electrophotographic photosensitive member of the present invention varies depending on the support used, various shapes such as a drum shape, a plate shape, a sheet shape, and a belt shape are possible.

The thickness of the photosensitive layer in the electrophotographic photosensitive member of the present invention is preferably 5 to 50 μm, particularly preferably 15 to 30 μm in the case of a single-layer photosensitive member. Also,
In the case of a laminated photoreceptor, the thickness of the charge generation layer is preferably 5 μm or less, and particularly preferably in the range of 0.01 to 2 μm. The thickness of the charge transport layer is preferably in the range of 3 to 50 μm, and particularly preferably in the range of 5 to 30 μm.

The thickness of the intermediate layer is preferably 5 μm or less, more preferably 0.1 to 1 μm. The thickness of the surface protective layer is preferably 2 μm or less.
The range of 01 to 1 μmm is particularly preferred.

The proportion of the methylidenehydrazonofluorene derivative in the electrophotographic photoreceptor of the present invention is 5% in the photosensitive layer.
Can be appropriately selected within the range of 10 to 100% by weight.
A range of 0% by weight m is particularly preferred.

A hole transporting material can be used in combination with the photoconductive layer containing the electron transporting material of the electrophotographic photosensitive member of the present invention.

Examples of the hole transporting material which can be used together with the electron transporting material include: 1) carbazoles such as N-ethylcarbazole, N-isopropylcarbazole and N-phenylcarbazole; ) N-methyl-N-phenylhydrazino-3-methylidene-9-ethylcarbazole, N, N
-Diphenylhydrazino-3-methylidene-9-ethylcarbazole, p- (N, N-dimethylamino) benzaldehyde diphenylhydrazone, p- (N, N-diethylamino) benzaldehyde diphenylhydrazone,
p- (N, N-diphenylamino) benzaldehyde diphenylhydrazone, 1- [4- (N, N-diphenylamino) benzylideneimino] -2,3-dimethylindoline, N-ethylcarbazole-3-methylidene-N
Hydrazones such as -aminoindoline, N-ethylcarbazol-3-methylidene-N-aminotetrahydroquinoline; 3) oxadiazo such as 2,5-bis (p-diethylaminophenyl) -1,3,4-oxadiazol 4) 1-phenyl-3- (p-diethylaminostyryl) -5- (p-diethylaminophenyl) pyrazoline, 1- [quinolyl- (2)]-3- (p-diethylaminophenyl) pyrazoline, etc. Pyrazolines, 5)
Tri-p-tolylamine, N, N'-diphenyl-N,
Arylamines such as N'-bis (3-methylphenyl) -1,1'-biphenyl-4,4'-diamine; 6)
1,1-bis (p-diethylaminophenyl) -4,4
Butadiene such as diphenyl-1,3-butadiene,
7) styryls such as 4- (2,2-diphenylethenyl) -N, N-diphenylbenzeneamine and 4- (1,2,2-triphenylethenyl) -N, N-diphenylbenzeneamine; No. Examples of the polymer compound include, for example, poly-N-vinylcarbazole, halogenated poly-N-vinylcarbazole, polyvinylpyrene, polyvinylanthracene, polyvinylacridine,
Examples thereof include poly-9-vinylphenylanthracene, pyrene-formamide resin, ethylcarbazole-formaldehyde resin, triphenylmethane polymer, and polyphenylalkylsilane. The hole transporting material is not limited to those described here, and may be used alone or in combination of two or more.

When a hole transporting material is used in combination, the weight ratio of the electron transporting material to the hole transporting material can be used in the range of 1: 9 to 9: 1 and 2: 8 to 8: 8. : 2 is particularly preferred.

As the charge generating material used in the electrophotographic photoreceptor of the present invention, various materials can be used. For example, 1) azo pigments such as monoazo pigments, disazo pigments, and trisazo pigments, 2) various azo pigments Phthalocyanine pigments such as metal phthalocyanine, metal-free phthalocyanine, naphthalocyanine, etc. 3) Condensed polycyclic pigments such as perinone pigments, perylene pigments, anthraquinone pigments, quinacridone pigments, indigo pigments, thioindigo pigments, 4) squarium pigments, 5) Azulene dyes, 6) pyrylium salt dyes such as pyrylium salts and thiapyrylium salts, 7) cyanine dyes, 8) triphenylmethane dyes, 9) selenium compounds such as selenium, selenium / tellurium, selenium / arsenic, and oxidation Inorganic materials such as zinc, cadmium sulfide, cadmium selenide, and amorphous silicon It can be mentioned. Others
If the material absorbs light and efficiently generates charge carriers,
Any material can be used. The charge generation material is not limited to those described herein, and may be used alone or in combination of two or more.

The proportion of the charge generating material is 5 to 100% by weight.
Is particularly preferable, and 10 to 70% by weight is particularly preferable.

In the photoconductive layer of the electrophotographic photoreceptor of the present invention, a plasticizer and a sensitizer may be used together with a binder resin, if necessary.

Various binder resins can be used as needed, but it is preferable to use a polymer compound which is hydrophobic and can form an electrically insulating film. Examples of such high-molecular polymers include polycarbonate resins, polyester resins, methacrylic resins, acrylic resins, polyvinyl chloride resins, polyvinylidene chloride resins, polyarylate resins, polystyrene resins, and polyvinyl acetate. Resin, polyvinyl butyral
Resin, diallyl phthalate resin, styrene-butadiene copolymer, vinyl chloride-vinyl acetate-maleic anhydride copolymer, silicone resin, silicone-alkyd resin,
Phenolic resin, epoxy resin, styrene-alkyd resin, poly-N-vinyl carbazole resin, urea resin,
Polysulfone resin and the like can be mentioned. The binder resin is not limited to those described herein, and may be used alone or as a mixture of two or more.

Examples of the plasticizer include biphenyl, biphenyl chloride, o-ter-phenyl, p-ter-phenyl,
Dibutyl phthalate, diethyl glycol phthalate,
Examples include dioctyl phthalate, triphenyl phosphoric acid, dimethyl naphthalene, benzophenone, chlorinated paraffin, polypropylene, polystyrene, various fluorohydrocarbons, and the like.

As the sensitizer, any known sensitizer can be used. Examples include chloranil, tetracyanoethylene, methyl violet, rhodamine B, cyanine dye, merocyanine dye, pyrylium dye, thiapyrylium dye and the like.

The electrophotographic photoreceptor of the present invention has storability,
In order to improve durability and environmental resistance, the photosensitive layer may contain a deterioration inhibitor such as an antioxidant, an ultraviolet absorber or a light stabilizer, if necessary. Examples of these substances include a phenol compound, a hydroquinone compound, and an amine compound.

Further, in order to improve the film formability, flexibility, and mechanical strength of the electrophotographic photoreceptor, in addition to the above-mentioned binder resin, in addition to the above-mentioned plasticizer, a surface modifier or the like is added. Agents can also be used.

As the surface modifier, for example, silicone oil, fluorine resin and the like can be mentioned.

The material used for the intermediate layer in the electrophotographic photoreceptor of the present invention includes, in addition to the polymer compound used for the binder resin, casein, gelatin, ethyl cellulose, nitrocellulose. Carboxy-methyl cellulose, vinylidene chloride-based polymer latex,
Styrene-butadiene-based polymer latex, polyvinyl alcohol, polyamide, polyurethane, phenolic resin, aluminum oxide, tin oxide, titanium oxide, and the like.

The materials used for the surface protective layer in the electrophotographic photoreceptor of the present invention include, in addition to the high molecular compounds used for the binder resin, casein, gelatin, ethyl cellulose, nitrocellulose. Carboxy-methyl cellulose, vinylidene chloride-based polymer latex,
Styrene-butadiene-based polymer latex, polyvinyl alcohol, polyamide, polyurethane, phenolic resin, aluminum oxide, tin oxide, titanium oxide, and the like.

In the present invention, when a resin dispersion film is used for forming a photoconductive layer, an intermediate layer, a surface layer, etc., as a solvent for dissolving the binder resin, for example, methanol, ethanol, etc. Alcohols such as n-propanol and n-propanol; ketones such as acetone, methyl ethyl ketone and cyclohexanone; amides such as N, N-dimethylformamide and N, N-dimethylacetamide; tetrahydrofuran, dioxane, methyl cellosolve and the like. Esters such as methyl acetate and ethyl acetate; sulfoxides and sulfones such as dimethyl sulfoxide and sulfolane; aliphatic halogenated hydrocarbons such as dichloromethane, chloroform, carbon tetrachloride and trichloroethane; benzene, toluene and xylene And aromatics such as monochlorobenzene and dichlorobenzene. It is.

Various methods can be used to form the photosensitive layer. Examples of the coating method include immersion coating, spray coating, spinner coating, and bead coating. Coating methods such as a coating method, a curtain coating method, a wire bar coating method, a blade coating method, and a roller coating method can be used.

The present invention includes the following embodiments in addition to those described in the claims. 1. In an electrophotographic photoreceptor having a photosensitive layer on a conductive support, a binder resin layer in which a charge generation material is dispersed on a conductive support and a binder resin in which a hole transport material is dispersed A layer having a photosensitive layer laminated in this order, wherein the hole transport material is a methylidenehydrazonofluorene derivative represented by the above general formula [1].

2. An electrophotographic photosensitive member having a photosensitive layer on a conductive support has a photosensitive layer in which a binder resin layer in which a charge generation material and a hole transport material are dispersed is laminated on the conductive support. A single-layer type positively charged photoconductor for electrophotography, wherein the hole transporting material is a methylidenehydrazonofluorene derivative represented by the above general formula [1].

3. An electrophotographic photoreceptor having a photosensitive layer on a conductive support, wherein the conductive support has a photosensitive layer in which a binder resin layer in which a charge generation material and an electron transport material are dispersed is laminated. A single-layer negatively charged photoconductor for electrophotography, wherein the electron transporting material is a methylidenehydrazonofluorene derivative represented by the above general formula [1].

[0053]

EXAMPLES The present invention will now be described specifically with reference to examples, but the present invention is not limited to the examples. In the examples, "parts" represents "parts by weight",
“%” Represents “% by weight”.

<Example 1> 2 parts of α-type titanyl phthalocyanine and a butyral resin (trade name “ESREC BH-3”)
1 part of Sekisui Chemical Co., Ltd.) was added to a mixture of 52 parts of dichloromethane and 78 parts of 1,1,2-trichloroethane, and dispersed and mixed in a sand mill to obtain a charge generation material dispersion.

This dispersion was applied onto a polyester film on which aluminum had been deposited so that the film thickness after drying was 0.1 μm to form a charge generation layer. Next, 10 parts of the exemplified compound (7) and a polycarbonate resin (trade name "UPILON Z200" manufactured by Mitsubishi Gas Chemical Company) 1
0 parts is dissolved in a mixed solvent of 36 parts of 1,1,2-trichloroethane and 54 parts of dichloromethane, and a paint obtained is applied on the charge generation layer so that the film thickness after drying is 20 μm, and charge transport is performed. By forming the layers, a laminated electrophotographic photoreceptor was produced.

The photoreceptor was charged by a corona discharge of +6 KV in a dark place using an electrostatic copying paper tester (trade name "SP428", manufactured by Kawaguchi Electric Works). The surface potential V ₀ (V) was measured.
Next, the surface potential V ₁₀ (V) of the photoconductor when left in a dark place for 10 seconds was measured. From V ₀ and V ₁₀ , the charge retention rate of the surface potential of the photoconductor (DDR (%): (V ₁₀ / V
₀ ) × 100) was calculated. Further, exposure is performed with light having a wavelength of 780 nm and an exposure energy of −10 mW / m ² with respect to the surface potential V ₁₀ , and the exposure amount E _1/2 (mJ / m) is reduced by half from the time until the surface potential becomes half of V _10. ² ) Asked. Furthermore, the surface potential 15 seconds after the start of exposure, that is, the residual potential V
_R (V) was measured.

Examples 2 to 5 Exemplified compounds (9), (15), (20) and (23) instead of Exemplified compound (7)
A laminated electrophotographic photoreceptor was prepared in the same manner as in Example 1 except that was used, and the photoreceptor was evaluated in the same manner as in Example 1.

Comparative Example 1 In Example 1, the following structural formula (A) was used instead of the exemplary compound (7).

[0059]

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A photoconductor for electrophotography was prepared in the same manner as in Example 1 except that the electron transporting material represented by
The photoreceptor was evaluated in the same manner as described above.

Comparative Example 2 In Example 1, the following structural formula (B) was used instead of the exemplary compound (7).

[0062]

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A photoconductor for electrophotography was prepared in the same manner as in Example 1 except that the charge transporting material represented by the formula (1) was used, and the photoconductor was evaluated in the same manner as in Example 1.

Table 1 shows the measurement results of the electrophotographic characteristics of the photoreceptors evaluated in Examples 1 to 5 and Comparative Examples 1 and 2.

[0065]

[Table 1]

(In the table, V ₀ and V _R represent (V), DDR represents (%), and E _1/2 represents (mJ / m ² ).)

As is clear from Table 1, Examples 1 to 5
The photoreceptor for electrophotography used in this method has a charge retention (DD)
R), high sensitivity (half-exposure), residual charge
Position (V _R) You can see that the rank is low. In addition, conventional negatively charged
More adverse effects of ozone than multilayer photoconductors for electrophotography
Less.

Example 6 4 parts of Exemplified Compound (6) as an electron transporting material and the following structural formula as a hole transporting material

[0069]

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Is dissolved in 34 parts of a 34% polycarbonate resin (trade name "UPIRON Z200" manufactured by Mitsubishi Gas Chemical Company) (solvent: chloroform) in 4 parts of the triphenylamine derivative (C). did. This solution was added to 44 parts of a dispersion liquid (3%) of α-oxytitanium phthalocyanine in polycarbonate resin (same as above), and subjected to ultrasonic treatment for 30 minutes to prepare a photoconductor coating liquid.

This dispersion was applied onto a polyester film on which aluminum had been vapor-deposited so that the film thickness after drying was 25 μm to produce a single-layer type electrophotographic photoreceptor. Next, the photosensitive member was evaluated in the same manner as in Example 1.

<Examples 7 and 8> A single-layer type electrophotographic photoreceptor was prepared in the same manner as in Example 6, except that the exemplified compounds (18) and (24) were used instead of the exemplified compound (6). Then, the photosensitive member was evaluated in the same manner as in Example 1.

<Comparative Examples 3 and 4> In Example 6, the electron transport material represented by the structural formulas (A) (Comparative Example 3) and (B) (Comparative Example 4) was replaced with the exemplified compound (6). Except for using, a photoconductor for electrophotography was prepared in the same manner as in Example 6,
The evaluation of the photosensitive member was performed in the same manner as in Example 1.

<Examples 9 to 11> and <Comparative Examples 5 to 6>
In the evaluation of the electrophotographic photosensitive members prepared in Examples 6 to 8 and Comparative Examples 3 and 4, the photosensitive members were evaluated in the same manner as in Example 1 except that the charging potential was -6 KV. Was.

Table 2 shows the measurement results of the electrophotographic characteristics of the photoreceptors evaluated in Examples 6 to 11 and Comparative Examples 3 to 6.

[0076]

[Table 2]

(In the table, V ₀ and V _R represent (V), DDR represents (%), and E _1/2 represents (mJ / m ² ).)

As is clear from Table 2, the electrophotographic photoreceptor of the present invention exhibits excellent electrophotographic characteristics not only under positive charging but also under negative charging. The single-layer photosensitive system for electrophotography also has excellent charge retention, excellent residual potential, and excellent sensitivity.

It can also be seen that, in the case of a single-layer type photoreceptor, the degree of improvement in sensitivity is higher when used negatively than when used positively. Example 1
The positively charged photoreceptors of Nos. To 8 degraded more slowly than the negatively charged photoreceptors of Examples 9 to 11, and caused less environmental pollution during long-term use. Further, the positively charged photoreceptors of Examples 6 to 8 deteriorated more slowly than the negatively charged photoreceptors of Examples 9 to 11, and had less environmental pollution during long-term use.

[0080]

Since the electrophotographic photoreceptor of the present invention uses a methylidenehydrazonofluorene derivative having a specific chemical structure as a charge transporting material, it has an excellent potential irrespective of a single-layer type or a multilayer type. This provides a particularly remarkable effect that a photoreceptor having both a retention rate and excellent sensitivity can be provided. It is extremely useful as a photoconductor for electrophotography, which is superior in both positive and negative charging as compared with the related art.

Claims (1)

[Claims] 1. An electrophotographic photosensitive member having a photosensitive layer on a conductive support, wherein the photosensitive layer contains a methylidenehydrazonofluorene derivative represented by the general formula [1]. Photoreceptor. Embedded image (Wherein, R ¹ and R ² each independently represent an alkyl group, an aryl group, an aralkyl group, or a heterocyclic group which may have a substituent. Further, R ¹ and R ² form a ring. N may be 1
Represents a number from 4 to 4. )