JP2007121558A - Electrophotographic photoreceptor using stilbene derivative - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrophotographic photoreceptor excellent in sensitivity characteristics by using a charge transport agent excellent in solubility with an organic solvent or solubility with a binder resin used for formation of a photosensitive layer. <P>SOLUTION: The electrophotographic photoreceptor has a photosensitive layer containing at least a charge generating agent and a charge transport agent, wherein the charge transport agent is one among the compounds expressed by at least general Formulae (1) and (2). In the Formulae, R<SB>1</SB>to R<SB>12</SB>are identical or different groups, each representing a 1-6C alkyl group, a 1-6C alkoxy group, a 6-20C aryl group, or a 6-20C aralkyl group; Ar represents a 6-20C aryl group or a 3-20C heterocyclyl group; and each of m and n represents an integer of 0 to 3. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an electrophotographic photosensitive member containing a charge transporting agent excellent in solubility in an organic solvent and compatibility with a binder resin used for forming a photosensitive layer.

  Conventionally, inorganic materials such as selenium, cadmium sulfide, and amorphous silicon have been used as photoconductive materials for photoconductors utilizing electrophotography. These inorganic photoreceptors have many advantages, but have disadvantages such as being harmful and costly.

  For this reason, in recent years, many organic photoreceptors using organic substances that have solved these drawbacks have been proposed and put into practical use. The organophotoreceptor is easier to manufacture than conventional inorganic photoreceptors, and there are various options for the constituent materials of the photoreceptor such as a charge transport agent, a charge generator, and a binder resin. There is an advantage that is high.

  The organic photoreceptor includes a single-layer photoreceptor in which a charge generator is dispersed in a photosensitive layer containing a charge transport agent, a charge generation layer containing a charge generator, and a charge transport layer containing a charge transport agent. There are laminated type photoconductors in which are separated and laminated. In any of the above photoreceptors, in order to improve the sensitivity characteristic, it is required to use a charge transport agent having a high charge transport property. Thus, various charge transport agents have been proposed, and Patent Documents 1 and 2 disclose stilbene derivatives represented by the following general formula HT-A.

However, HT-A disclosed in the above publication has a problem of insufficient sensitivity.
JP 60-175052 A JP 60-175052 A

  An object of the present invention is to provide an electrophotographic photoreceptor excellent in sensitivity characteristics by using a charge transfer agent excellent in solubility in an organic solvent and compatibility with a binder resin used for forming a photosensitive layer.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that the compounds represented by the following general formulas (1) to (2) in the charge transport agent have solubility in organic solvents and binders. A new fact that the compatibility with the resin can be remarkably improved and the high-sensitivity electrophotographic photosensitive member can be obtained by preventing the precipitation of crystals in the photosensitive layer has been found and the present invention has been completed. It came.

  The electrophotographic photosensitive member of the present invention is an electrophotographic photosensitive member provided with a photosensitive layer containing at least a charge generating agent and a charge transporting agent, and the charge transporting agent includes at least the following general formula (1) and the following general formula ( It is a compound represented by any one of the compounds represented by 2).

(In the formula, R _{1 to} R ₁₂ are the same or different groups and are an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, an aryl group having 6 to 20 carbon atoms, or 6 carbon atoms. -20 represents an aralkyl group, Ar represents an aryl group having 6 to 20 carbon atoms and a heterocyclyl group having 3 to 20 carbon atoms, and m and n represent any integer of 0 to 3).

  According to the charge transfer agent represented by the general formulas (1) to (2) of the present invention, the compatibility with the binder resin is remarkably improved, the precipitation of crystals in the photosensitive layer is prevented, and the high sensitivity electrophotography. Photoconductor can be obtained

  Hereinafter, embodiments of the present invention will be described in detail. The electrophotographic photosensitive member of the present invention is provided with a photosensitive layer containing at least a charge generating agent and a charge transfer agent, and the charge transfer agent is a stilbene derivative. ).

  The charge transfer agent according to the present invention is represented by the above general formulas (1) to (2) as described above, and is represented by the following general formula (3) in two phenyl groups bonded to a nitrogen atom. The substitution positions of the substituents to be represented are different from each other and are not targeted.

In the general formula (3), R _7, R _{10 to} R _{12 and} m are the same as above.

In the compounds represented by the formulas (1) and (2), Ar preferably has a substituent in the ortho position with respect to the nitrogen atom. Specifically, when Ar is a phenyl group, it is preferable that the phenyl group has a substituent at the ortho position with respect to the nitrogen atom, as described later (HT-1). The substituent is an alkyl group, an alkoxy group, or an aryl group.
Thus, Ar has a substituent in the ortho position with respect to the nitrogen atom, so that it can effectively have a twisted structure in the molecule of the charge transport agent, and the solubility of the compound in the binder resin is improved. The mobility of the charge transfer agent can be increased.

Examples of the alkyl group in R _{1 to} R ₁₂ include a methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, s-butyl group, t-butyl group, pentyl group, isopentyl group, C1-C6 alkyl groups, such as a neopentyl group and a hexyl group, are mentioned. Examples of the alkoxy group include 1 to 1 carbon atoms such as methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, s-butoxy, t-butoxy, pentyloxy, isopentyloxy, neopentyloxy, hexyloxy and the like. 6 alkoxy groups.

The aryl group in R ₁ to R _12, for example, a phenyl group, a naphthyl group, a tolyl group, a xylyl group, anthryl group, and an aryl group having 6 to 20 carbon atoms such as phenanthryl group. The aryl group may have a substituent, and examples of the substituent include an alkyl group having 1 to 6 carbon atoms and an alkoxy group having 1 to 6 carbon atoms.

Examples of the aralkyl group in R _{1 to} R ₁₂ include benzyl, α-methylbenzyl, phenethyl, styryl, cinnamyl, 3-phenylpropyl, 4-phenylbutyl, 5-phenylpentyl, 6-phenylhexyl, and the like. -20 aralkyl groups.

Examples of the heterocyclyl group in R _{1 to} R ₁₂ include a pyridyl group, a pyrrolidinyl group, and a thienyl group.

  Examples of the compound represented by the above formula (1) according to the present invention include HT-1 and HT-2 shown below. Examples of the compound represented by the formula (2) include HT-3 shown below. However, in the present invention, the compound of the formula (1) or (2) that can be used as the charge transport agent is not limited to these.

(Synthesis method)
Any compound included in the formula (1) in the present invention can be synthesized by a known production method. For example, HT-1 can be obtained by the following method using a coupling reaction, a formylation reaction, a Wittig reaction, and the like. The method described below is a compound represented by the above formula (1), where R ₁ to R ₁₂ is a hydrogen atom, will be described in accordance with the following reaction formulas (1) to (3).

  First, a compound represented by formula (13) is obtained by Wittig reaction. That is, a compound of the formula (12) obtained by reacting triethyl phosphite with a compound of the formula (11), dry THF (tetrahydrofuran) and sodium methoxide are added, and the temperature of 0 to 10 ° C. is added. And stirring for 20 to 60 minutes. Next, benzaldehyde dissolved in dry THF is added to the obtained reaction solution, and the mixture is stirred at room temperature for 10 to 15 hours to obtain a compound represented by the formula (13).

In the reaction formula (1), n is the same as described above.

  Next, in the following reaction formula (2), for the compound represented by the formula (16), the raw material (11) in the reaction formula (1) is changed to the compound of the formula (14) in the following reaction formula (2). Others can be obtained in the same manner as in reaction formula (1).

In reaction formula (1), m is the same as described above.

  Next, by performing the coupling reaction in two stages, a compound represented by the following formula (19) can be obtained.

  That is, as the first step, the compound of formula (16) obtained above and the amine derivative represented by formula (17) in the following reaction formula (3) are heated at 100 ° C. in the presence of a palladium catalyst in an argon atmosphere. The reaction is performed by heating and stirring at ~ 120 ° C for 1 to 10 hours. After the reaction, the organic layer is washed, dried, and purified by column chromatography to obtain a compound represented by the following formula (18). Further, as the second step, the obtained compound (18) and the compound (13) obtained by the above reaction formula (1) are carried out in the same manner as in the first step reaction and purification, whereby the formula (19) To obtain a compound represented by:

  In the reaction formula (3), n and m are the same as described above.

  Other compounds included in the formula (1) in the present invention can be synthesized in the same manner as described above by replacing the compounds (11), (14) and (17) with compounds having a desired group. it can. Moreover, the compound of Formula (2) in this invention can change the compound (14) in Reaction formula (2) into the following compound (20), and can perform reaction similar to the above.

  In formula (20), m is the same as described above.

  As described above, the electrophotographic photosensitive member of the present invention contains a charge transporting agent of the compound of formula (1) and / or formula (2) in the photosensitive layer.

  The photosensitive layer is composed of a single layer type photoreceptor in which a charge generator and a charge transport agent are mixed in the same layer, a layer containing a charge generator, and a layer containing a charge transport agent. Each photosensitive layer is obtained by dissolving and dispersing each component such as a charge generating agent and a charge transporting agent in a solvent together with a binder resin and the like. It is formed by applying and drying the resulting coating solution on a conductive substrate.

Since the electrophotographic photosensitive member of the present invention contains the compounds contained in the above formulas (1) to (2) having good solubility in a solvent and high charge transportability, as described above, the conventional electrophotography. High sensitivity compared to the photoreceptor. In addition, according to the electrophotographic photoreceptor of the present invention, the long-term stability of the photosensitive layer is improved because the compatibility between the compounds contained in the formulas (1) and (2) and the binder resin is good. To do.
(Charge generator)
Next, examples of the charge generating agent according to the present invention include metal-free phthalocyanine, hydroxygallium phthalocyanine, chlorogallium phthalocyanine, α-titanyl phthalocyanine, Y-titanyl phthalocyanine, and phthalocyanine pigments such as V-hydroxygallium phthalocyanine and perylene pigments. Bisazo pigments, diketopyrrolopyrrole pigments, metal-free naphthalocyanine pigments, metal naphthalocyanine pigments, squaraine pigments, trisazo pigments, indigo pigments, azurenium pigments, cyanine pigments, pyrylium pigments, ansanthrone pigments, triphenylmethane pigments, Organic photoconductors such as selenium pigments, toluidine pigments, pyrazoline pigments, quinacridone pigments, selenium, selenium-tellurium, selenium-arsenic, cadmium sulfide, amorphous silicon Inorganic photoconductive material and the like such emissions. These charge generating agents may be used alone or in combination of two or more.

In the present invention, a phthalocyanine pigment, particularly a metal-free phthalocyanine (for example, X-type metal-free phthalocyanine), titanyl phthalocyanine, hydroxygallium phthalocyanine and chlorogallium phthalocyanine is used as a charge generator. In view of the electrical characteristics of the photoreceptor when red or infrared light of 650 nm or more is used as the exposure light source, etc.
(Hole transport agent)
The charge transport agent used in the electrophotographic photoreceptor of the present invention is a hole transport agent, and is at least a compound represented by the formula (1) or (2).

In the electrophotographic photoreceptor of the present invention, various conventionally known hole transport agents may be contained in the photosensitive layer in combination with the compounds (1) to (2). Examples of such other hole transporting agents include bisstilbenediamine derivatives, bistriphenylamine derivatives, triphenylaminostyryl derivatives, stilbeneamine-hydrazone derivatives, and the like.
(Electron transfer agent)
Examples of the electron transporting agent include diphenoquinone derivatives, benzoquinone derivatives, naphthoquinone derivatives, anthraquinone derivatives, malononitrile derivatives, thiopyran derivatives, thioxanthone derivatives (2,4,8-trinitrothioxanthone, etc.), fluorenone derivatives (3,4,5,7). -Tetranitro-9-fluorenone derivatives, etc.), anthracene derivatives, acridine derivatives, dinitrobenzene, dinitroanthracene, dinitroacridine, succinic anhydride derivatives, maleic anhydride derivatives, dibromomaleic anhydride derivatives, etc. Can be mentioned.
(Binder resin)
In the electrophotographic photoreceptor of the present invention, conventionally known various resins can be adopted as the binder resin for forming a layer containing each component such as a charge generator and a charge transport agent. Among them, the use of at least one resin selected from the group consisting of polycarbonate, polyester, polyarylate, polystyrene, and polymethacrylic acid ester as the binder resin is the compound represented by the above formula (1) according to the present invention. From the standpoint of further improving the compatibility, and the properties such as the strength and abrasion resistance of the photosensitive layer. Moreover, the binder resin exemplified above is excellent in compatibility with the charge generating agent and the charge transport agent, and does not have a site in the molecule that interferes with the charge transport property of the charge transport agent. Therefore, by using such a binder resin, an electrophotographic photosensitive member with higher sensitivity can be obtained.
(Dispersion medium)
As a dispersion medium used for preparing a coating solution for forming a photosensitive layer by dispersing and dissolving the charge generating agent, hole transporting agent, electron transporting agent, binder resin and the like exemplified above, a coating solution for forming a photosensitive layer is used. Various organic solvents conventionally used can be used. Specifically, alcohols such as methanol, ethanol, isopropanol and butanol; aliphatic hydrocarbons such as n-hexane, octane and cyclohexane; aromatic hydrocarbons such as benzene, toluene and xylene; dichloromethane, dichloroethane and chloroform , Halogenated hydrocarbons such as carbon tetrachloride and chlorobenzene; ethers such as dimethyl ether, diethyl ether, tetrahydrofuran, dioxane, dioxolane, ethylene glycol dimethyl ether and diethylene glycol dimethyl ether; ketones such as acetone, methyl ethyl ketone and cyclohexanone; ethyl acetate and methyl acetate And esters such as dimethylformaldehyde, dimethylformamide, and dimethyl sulfoxide.

In addition, although not limited thereto, tetrahydrofuran, dioxane, dioxolane, cyclohexanone, among various organic solvents, are preferable for stably dispersing each component such as a charge generator, a charge transport agent, and a binder resin. It is preferable to use at least one organic solvent selected from the group consisting of toluene, xylene, dichloromethane, dichloroethane and chlorobenzene.
(Additive)
In the coating solution for forming the photosensitive layer, in addition to the above-mentioned components, various conventionally known additives such as an antioxidant, a radical scavenger, a singlet quencher are used as long as they do not adversely affect the electrophotographic characteristics. Deterioration inhibitors such as char and ultraviolet absorbers, softeners, plasticizers, surface modifiers, extenders, thickeners, dispersion stabilizers, waxes, acceptors, donors, and the like can be blended. In order to improve the sensitivity of the photosensitive layer, a known sensitizer such as terphenyl, halonaphthoquinones, and acenaphthylene may be used in combination with the charge generator. Further, a surfactant, a leveling agent or the like may be used in order to improve the dispersibility of the charge transport agent or charge generator and the smoothness of the photosensitive layer surface.
(Conductive substrate)
As the conductive substrate, various conductive materials can be used. For example, iron, aluminum, copper, tin, platinum, silver, vanadium, molybdenum, chromium, cadmium, titanium, nickel, palladium, indium, stainless steel And a simple metal such as brass, a plastic material on which the above metal is deposited or laminated, and glass coated with aluminum iodide, tin oxide, indium oxide, or the like. The conductive substrate is used in the form of a drum or a sheet according to the structure of the image forming apparatus to be used. The conductive substrate preferably has sufficient mechanical strength.

The conductive substrate used in the present invention is not limited to this, but the surface thereof may be subjected to an oxide film treatment or a resin film treatment.
(Manufacture of single layer type electrophotographic photoreceptor)
The single-layer type electrophotographic photosensitive member includes a charge generator, the compound (1) of the present invention (hole transport agent), a binder resin, and an electron transport agent and the above additives as necessary. The photosensitive layer forming coating solution thus obtained is dispersed or dissolved in an appropriate dispersion medium, coated on a conductive substrate, and dried to form a photosensitive layer.

  In the photosensitive layer forming coating solution, the charge generating agent may be blended in an amount of 0.1 to 50 parts by weight, preferably 0.5 to 30 parts by weight with respect to 100 parts by weight of the binder resin. What is necessary is just to mix | blend a hole transport agent in the ratio of 5-200 weight part with respect to 100 weight part of binder resin, Preferably it is 50-150 weight part. What is necessary is just to mix | blend an electron transport agent in the ratio of 5-200 weight part with respect to 100 weight part of binder resin, Preferably it is 10-100 weight part. In the case where the electron transport agent and the hole transport agent are used in combination, the total amount of the electron transport agent and the hole transport agent is 20 to 500 parts by weight, preferably 30 to 200 parts by weight with respect to 100 parts by weight of the binder resin. It is appropriate to do.

  The thickness of the photosensitive layer obtained by application of the coating solution for forming the photosensitive layer is preferably set to 5 to 100 μm, particularly 10 to 50 μm.

When preparing a coating solution for forming a photosensitive layer, the above-exemplified charge generator, charge transport agent, insoluble azo pigment, binder resin, etc., together with an appropriate solvent, roll mill, ball mill, attritor, paint shaker, ultrasonic dispersion What is necessary is just to disperse and mix using well-known means, such as a machine.
(Manufacture of multilayer electrophotographic photoreceptors)
In the case of a laminated photoreceptor, a charge generator and a hole transport agent are mixed together with a suitable binder resin and solvent using a roll mill, ball mill, attritor, paint shaker, ultrasonic disperser, etc. What is necessary is just to prepare and apply | coat this dispersion liquid on an electroconductive base | substrate by a well-known means, and to make it dry. The thickness of each layer after drying is 0.01 to 5 μm, preferably 0.1 to 3 μm for the charge generation layer, and 2 to 100 μm, preferably 5 to 50 μm for the charge transport layer.

  In the charge generation layer of the multilayer photoconductor, the charge generation agent is preferably contained in an amount of 5 to 1000 parts by weight, particularly 30 to 500 parts by weight, based on 100 parts by weight of the binder resin. In the charge transport layer, the hole transport agent may be contained in an amount of 10 to 100 parts by weight, particularly 30 to 80 parts by weight with respect to 100 parts by weight of the binder resin. Moreover, when using together a positive hole transport agent and an electron transport agent, it is good to contain the total amount in the ratio of 10-500 weight part with respect to 100 weight part of binder resin, especially 30-200 weight part.

  Between the single layer type photosensitive layer or the multilayer type photosensitive layer and the conductive substrate, or between the charge generation layer and the charge transport layer constituting the multilayer type photosensitive layer, as long as the characteristics of the photosensitive member are not hindered. A layer, a barrier layer, or the like may be formed. Further, a protective layer may be formed on the surface of the photosensitive layer.

  Hereinafter, the electrophotographic photosensitive member of the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited only to the following Examples.

(Synthesis of hole transport agent)
(1) Synthesis of Compound (HT-1) The compound represented by the above formula (HT-1) was synthesized according to the following reaction formulas (i) to (iii).
(1-1) First, a compound represented by the following formula (23) was synthesized according to the reaction formula (i).
20 g (0.098 mol) of the compound represented by the formula (21) and 30 g (0.181 mol) of triethyl phosphite were added to a 200 ml flask and reacted at 180 ° C. for 8 hours. After the reaction, the mixture was cooled, and excess triethyl phosphite was distilled off under reduced pressure to obtain a phosphonate derivative obtained by the formula (22).
Compound (22): White oil Yield 26.95 g Yield 90%
Next, 15 g (0.049 mol) of the compound (22) obtained above was added to a 500 ml two-necked flask and purged with argon. Further, 100 ml of dry THF and 15.2 g (0.79 mol) of 28% sodium methoxide were added. And stirred at 0 ° C. for 30 minutes. Next, a THF solution of benzaldehyde (benzaldehyde 6 g (0.057 mol) / dry THF 300 ml) was added, and the mixture was stirred at room temperature for 12 hours. The obtained reaction solution was poured into ion exchanged water, extracted with toluene, the organic layer was washed 5 times with ion exchanged water, the organic layer was dried over anhydrous sodium sulfate, and the solvent was distilled off. The residue was purified with a mixed solvent of toluene and methanol (toluene: methanol = 20 ml / 100 ml) to obtain a compound represented by the formula (23). Compound (23) White crystals Yield 10.57 g Yield 85%

(1-2) Next, a compound represented by the following formula (26) was synthesized according to the reaction formula (ii).

20 g (0.098 mol) of the compound represented by the formula (24) and 30 g (0.181 mol) of triethyl phosphite were added to a 200 ml flask and reacted at 180 ° C. for 8 hours. After the reaction, the mixture was cooled, and excess triethyl phosphite was distilled off under reduced pressure to obtain a phosphonate derivative obtained by the formula (25).
Compound (22): White oil Yield 26.95 g Yield 90%
Next, 15 g (0.049 mol) of the compound (25) obtained above was added to a 500 ml two-necked flask and purged with argon. Further, 100 ml of dry THF and 15.2 g (0.79 mol) of 28% sodium methoxide were added. And stirred at 0 ° C. for 30 minutes. Next, a THF solution of benzaldehyde (benzaldehyde 6 g (0.057 mol) / dry THF 300 ml) was added, and the mixture was stirred at room temperature for 12 hours. The obtained reaction solution was poured into ion exchanged water, extracted with toluene, the organic layer was washed 5 times with ion exchanged water, the organic layer was dried over anhydrous sodium sulfate, and the solvent was distilled off. The residue was purified with a mixed solvent of toluene and methanol (toluene: methanol = 20 ml / 100 ml) to obtain a compound represented by the formula (26). Compound (26) White crystals Yield 9.95 g Yield 80%

  (1-3) Next, a compound represented by the formula (HT-1) was synthesized according to the reaction formula (iii). In a 2 L two-necked flask, 19.55 g (0.0755 mol) of the compound (23) obtained in the above (1-1), 0.066 g (0.19 mmol) of tri-tert-butylphosphine, and 0.80 of palladium acetate. 086 g (0.094 mmol), sodium butoxide 7.68 g (0.08 mol), 10.2 g (0.0755 mol) of an aniline derivative represented by the following formula (27), and 500 ml of o-xylene were added, and the atmosphere was replaced with argon. Stir at 120 ° C. for 5 hours. After the reaction, the reaction solution was cooled to room temperature, the reaction solution was washed three times with ion-exchanged water, and anhydrous sodium sulfate and activated clay were added to the organic layer for drying and adsorption treatment. Thereafter, xylene was removed by distillation under reduced pressure, and then the residue was purified by column chromatography (developing solvent: chloroform / hexane) to obtain a compound represented by the formula (28).

Compound (28) Yield 18.9 g Yield 80%
Subsequently, 4.69 g (0.018 mol) of the compound (26) obtained in the above (1-2), 0.016 g (0.0453 mmol) of tri-tert-butylphosphine, and palladium acetate 0 0.021 g (0.023 mmol), sodium butoxide 2.88 g (0.03 mol), 5.665 g (0.018 mol) of the compound (23) obtained in (iii) above, and 200 ml of o-xylene were added, The atmosphere was replaced with argon, and the mixture was stirred at 120 ° C. for 3 hours. After the reaction, the reaction solution was cooled to room temperature, the reaction solution was washed three times with ion-exchanged water, and anhydrous sodium sulfate and activated clay were added to the organic layer, followed by drying and adsorption treatment. Thereafter, xylene was removed by distillation under reduced pressure, and then the residue was purified by column chromatography (developing solvent: chloroform / hexane) to obtain a compound represented by the formula (HT-1). Compound (HT-1) Yield 6.67 g Yield 75%

(2) Synthesis of HT-2 In the synthesis of HT-1, the HT-2 in the present invention is obtained by replacing the compound (21) described above with a compound represented by the following formula (29) and replacing the compound (24) described above. It synthesize | combined like HT-1 except having replaced with the compound represented by following formula (30).

(3) Synthesis of HT-3 In the synthesis of HT-1, the HT-3 in the present invention is obtained by replacing the compound (24) described above with the compound represented by the following formula (31) in the synthesis of HT-1. The compound was synthesized in the same manner as HT-1, except that the compound represented by the following formula (32) was used.

[Examples 1-6 and Comparative Examples 1-6]
[Manufacture of electrophotographic photosensitive member]
(Hole transport agent)
As the hole transporting agent, the above-described HT-1, 2 and the above-described hole transporting agent (HT-A) and the compound represented by the following formula (HT-B) were used.

(Electron transfer agent)
As the electron transport agent, the following three types of electron transport agents (ET-1 to ET-3) were used.

Example 1
5 parts by weight of X-type metal-free phthalocyanine as a charge generating agent, 60 parts by weight of HT-1 as a hole transporting agent, 50 parts by weight of ET-1 as an electron transporting agent, and 100 parts by weight of polycarbonate as a binder resin Were mixed and dispersed in a ball mill for 50 hours together with 800 parts by weight of tetrahydrofuran as a solvent to prepare a coating solution for a single-layer type photosensitive layer. Next, this coating solution was applied onto a conductive substrate made of an aluminum base tube by a dip coating method, and dried with hot air at 100 ° C. for 30 minutes to produce a single-layer type photoreceptor having a photosensitive layer thickness of 25 μm.
(Examples 2-6, Comparative Examples 1-6)
In the coating solution for single-layer type photosensitive layer produced in Example 1, HT-1, HT-2, HT-A, HT-B as a hole transport agent and ET-1 to ET-3 as an electron transport agent, A single-layer photoconductor was produced in the same manner as in Example 1 using the combinations shown in Table 1.
(Evaluation test and evaluation method)
Any of the electrophotographic photoreceptors produced in Examples 1 to 6 and Comparative Examples 1 to 6 was installed in a GENTEC drum sensitivity tester, and an electrical property test and the presence or absence of crystallization on the drum surface were evaluated. It was. The electric characteristics test, first, the initial surface potential V ₀ which has been charged so that + 700 V. Next, monochromatic light (light intensity: 1.5 μJ / cm ² ) having a wavelength of 780 nm (half-value width: 20 nm) extracted from the white light of the halogen lamp using a band-pass filter is irradiated on the surface of the photoreceptor for 1.5 seconds to be exposed. The surface potential at the time when 0.5 seconds had elapsed from the start was measured, and this was defined as the residual potential V _L (V). The presence or absence of crystallization on the drum surface was confirmed by visual observation at the final repetition point. These results are shown in Table 1.

Regarding the crystallization of the drum surface, the case where crystallization was not observed was marked with ◯, and the case where it was recognized was marked with x.
The results are shown in Table 1.

As is clear from Table 1, in the electrophotographic photoreceptors of Comparative Examples 1 to 3 using HT-A, the residual potential _VL is high, and sufficient sensitivity cannot be obtained, and HT-B is used. In all of the electrophotographic photoreceptors of Comparative Examples 4 to 6, crystals were precipitated in the photosensitive layer, and thus electrical characteristics could not be measured.

On the other hand, in the electrophotographic photoreceptors of Examples 1 to 9 using HT-1 to -3 of the present invention, the residual potential V _L is low, and high sensitivity is obtained by preventing the precipitation of crystals in the photosensitive layer. An electrophotographic photosensitive member can be obtained.

Claims (1)

An electrophotographic photosensitive member provided with a photosensitive layer containing at least a charge generating agent and a charge transport agent, wherein the charge transport agent is at least one of the compounds represented by the following general formulas (1) and (2): An electrophotographic photoreceptor, characterized in that

(In the formula, R _{1 to} R ₁₂ are the same or different groups and are an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, an aryl group having 6 to 20 carbon atoms, or 6 carbon atoms. -20 represents an aralkyl group, Ar represents an aryl group having 6 to 20 carbon atoms and a heterocyclyl group having 3 to 20 carbon atoms, and m and n represent any integer of 0 to 3).