JP2006208965A - Naphthalic imide derivative and electrophotographic photoreceptor using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a novel naphthalic imide derivative with which a high-sensitivity electrophotographic photoreceptor can be provided and an electrophotographic photoreceptor which is excellent in the sensitivity characteristics of the electrophotographic photoreceptor and in the durability and solvent resistance of a photosensitive layer. <P>SOLUTION: The naphthalic imide is expressed by General Formula (1). The electrophotographic photoreceptor has the photosensitive layer containing a charge generating agent, the naphthalic imide expressed by General Formula (1), and a binder resin on a conductive substrate. In the formula, R<SB>1</SB>to R<SB>3</SB>represent 1-6 C alkyl group which may have substituents, 1-6 C cycloalkyl groups, 6-20 C aryl groups, 7-18 C aralkyl groups. R<SB>4</SB>to R<SB>5</SB>represent 1-6 C alkyl group or 6-20 C aryl groups which may have substituents. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a novel naphthalimide derivative and an electrophotographic photoreceptor using the naphthalimide derivative.

An electrophotographic photosensitive member used in an image forming apparatus such as an electrostatic copying machine, a facsimile machine, or a laser beam printer has a photosensitive layer containing a charge generating agent, a charge transporting agent, and a binder resin on a conductive substrate. The so-called organic photoreceptor (OPC) formed is the mainstream.
For the purpose of improving the sensitivity characteristics of the organic photoreceptor, various charge transporting agents having excellent charge transporting ability have been developed. Patent Document 1 discloses excellent charge transporting ability (electron transporting ability). Examples of the compound include naphthalimide derivatives represented by the following general formula (I).

R represents a hydrocarbon residue which may have a substituent.
JP 7-49579 A

  In recent years, there has been a demand for further speeding up of image processing and higher image quality, and it is difficult to produce a highly sensitive photoconductor that can meet such requirements with a conventionally known electron transport agent.

  Accordingly, an object of the present invention is to provide a novel naphthalimide derivative capable of providing a highly sensitive electrophotographic photoreceptor and an electrophotographic photoreceptor excellent in sensitivity characteristics of the electrophotographic photoreceptor.

  As a result of intensive research to solve the above problems, the present inventor has found that when a group such as imide as an electron accepting group is introduced into a naphthalimide derivative, the conjugated system expands, and this compound is electrophotographic. By using it as an electron transport agent for photoreceptors, we obtained the knowledge that its sensitivity characteristics can be improved compared to conventional electrophotographic photoreceptors using naphthalimide derivatives. The present invention has been completed.

That is, the present invention
(1) A naphthalimide derivative characterized by being represented by the following general formula (1):

(R _{1 to} R ₃ are optionally substituted alkyl groups having 1 to 6 carbon atoms, alkoxy groups having 1 to 6 carbon atoms, cycloalkyl groups having 3 to 8 carbon atoms, and 6 to 20 carbon atoms. An aryl group and an aralkyl group having 7 to 18 carbon atoms, R ₄ and R _{5 each} represent an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 20 carbon atoms which may have a substituent.)

(2) An electrophotographic photosensitive member having a photosensitive layer on a conductive substrate, wherein the photosensitive layer contains a charge generating agent, a naphthalimide derivative represented by the following general formula (1), and a binder resin. An electrophotographic photoreceptor characterized by the above.

(R _{1 to} R ₃ are optionally substituted alkyl groups having 1 to 6 carbon atoms, alkoxy groups having 1 to 6 carbon atoms, cycloalkyl groups having 3 to 8 carbon atoms, and 6 to 20 carbon atoms. An aryl group and an aralkyl group having 7 to 18 carbon atoms, R ₄ and R _{5 each} represent an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 20 carbon atoms which may have a substituent.)

  According to the naphthalimide derivative represented by the general formula (1) of the present invention and the electrophotographic photosensitive member of the present invention including the naphthalimide derivative, the sensitivity characteristics of the electrophotographic photosensitive member can be improved. Furthermore, since the naphthalimide derivative represented by the general formula (1) is excellent in compatibility with the binder resin, it is possible to improve durability such as abrasion resistance and gas resistance of the photosensitive layer.

  The naphthalimide derivative of the present invention is represented by the above general formula (1).

In general formula (1), R _{1 to} R ₃ include an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, a cycloalkyl group having 3 to 8 carbon atoms, and an aryl having 6 to 18 carbon atoms. Group, and an aralkyl group having 7 to 18 carbon atoms.

Examples of the alkyl group having 1 to 6 carbon atoms include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, isopentyl, neopentyl, sec-pentyl, 2 -Methylpentyl, tert-pentyl, n-hexyl, isohexyl and the like.
Examples of the alkoxy group having 1 to 6 carbon atoms include methoxy group, ethoxy group, n-propoxy, isopropoxy, n-butoxy, s-butoxy, t-butoxy, n-pentyloxy, n-hexyloxy, n- Heptyloxy, n-octyloxy; perfluoromethoxy and the like.

Examples of the cycloalkyl group having 3 to 8 carbon atoms include cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl and the like.
Examples of the aryl group having 6 to 18 carbon atoms include phenyl, o, m or p-tolyl, 2,3-, 2,4-, 2,5-, 3,4- or 3,5-xylyl, o , M or p-cumenyl, mesityl, naphthyl, biphenyl and the like.

Examples of the aralkyl group having 7 to 18 carbon atoms include benzyl, 1-phenylethyl, phenethyl, 1-phenylpropyl, benzhydryl, o, m or p-methylbenzyl, 2,3-, 2,4-, 2, 5-, 3,4- or 3,5-dimethylbenzyl and the like can be mentioned.
Examples of R ₄ and R ₅ include an alkyl group having 1 to 6 prime numbers or an aryl group having 6 to 20 carbon atoms which may have a substituent.
The prime alkyl group is the same as the alkyl group described above. The aryl group having 6 to 20 carbon atoms which may have a substituent is the same as the aryl group described above. The substituent which may be substituted on the aryl group is represented by a prime number 1 to 6 alkyl group, a number 1 to 6 alkoxy group, a halogen atom, a nitro group, a cyano group, —COOR ₆ , or —OCOR _7. Groups. R ₆ and R ₇ are each independently a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, a cycloalkyl group having 3 to 8 carbon atoms, an aryl group having 6 to 18 carbon atoms, or an aralkyl group having 7 to 18 carbon atoms. Indicates.
Examples of the halogen atom include fluorine, chlorine, bromine and iodine.

R _{1 in the} general formula (1) is preferably a phenyl group, more preferably a phenyl group having an alkyl group having 1 to 6 carbon atoms at least at the 2-position or the 6-position. If R ₁ is a phenyl group, the conjugated system spreads, and if it is a phenyl group having an alkyl group having 1 to 6 carbon atoms at least at the 2-position or the 6-position, crystallization is prevented by steric hindrance, and the binder resin The compatibility with can be increased.
R ₂ and R _{3 in} the general formula (1) are preferably a hydrogen atom or an alkyl group having 1 to 6 carbon atoms. Since R ₂ and R ₃ are a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, the performance as an electron transport agent is improved, and the electron transport agent of the general formula (1) is obtained in a high yield. Can do.
R ₄ and R _{5 in} the general formula (1) are preferably a phenyl group which may have a substituent or a naphthyl group. By having such a substituent, the conjugated system of an electron transport agent spreads and high sensitivity can be achieved.

The method for synthesizing the naphthalimide derivative represented by the general formula (1) is not particularly limited. For example, as shown in the following reaction formula (1), a nitro group-substituted naphthalic anhydride represented by the formula (3) is used. It can be synthesized as a starting material.
That is, a nitro group-substituted naphthalic anhydride represented by the following formula (3) and a primary amine represented by the following formula (2) are used in the presence of acetic acid or a Lewis acid such as TiCl ₄ or ZnCl _2. , Mixed and heated to reflux to obtain naphthalic anhydride represented by the following formula (4). The obtained naphthalic anhydride is reduced to obtain a compound represented by the following formula (5), and then the compound (5) and a carbonyl derivative represented by the following formula (6) are dehydrated in an acetic acid solution. Thus, compound (1) is obtained.

(Wherein R _{1 to} R ₅ are the same as above).

When the naphthalimide derivative of the present invention is contained in the photosensitive layer of the electrophotographic photoreceptor, the naphthalimide derivative represented by the general formula (1) may be contained alone, or two or more kinds may be mixed. You may make it contain.
The electrophotographic photosensitive member of the present invention includes a photosensitive layer containing a charge generating agent, a naphthalimide derivative represented by the general formula (1), and a binder resin on a conductive substrate.

  In the electrophotographic photosensitive member of the present invention, the conductive substrate is not particularly limited, and examples thereof include various materials in which the substrate itself has conductivity or the surface of the substrate has conductivity. Specifically, for example, simple metals such as iron, aluminum, copper, tin, platinum, silver, vanadium, molybdenum, chromium, cadmium, titanium, nickel, palladium, indium, stainless steel, and brass, for example, the above metal is deposited Alternatively, a laminated plastic material, for example, a glass coated with aluminum iodide, tin oxide, indium oxide, or the like, for example, a resin substrate in which conductive fine particles such as carbon black are dispersed may be used. As the shape of the conductive substrate, various shapes such as a sheet shape and a drum shape can be adopted according to the structure of the image forming apparatus using the electrophotographic photosensitive member.

  In the electrophotographic photoreceptor of the present invention, the layer structure of the photosensitive layer is not particularly limited, and a so-called single layer in which a charge generator and a naphthalimide derivative represented by the general formula (1) are contained in the same layer. The layer-type photosensitive layer may be any of a so-called multilayer type photosensitive layer formed by separating a layer containing a charge generating agent (charge generating layer) and a layer containing a charge transporting agent (charge transporting layer). . A single layer type is preferable.

  In the electrophotographic photoreceptor of the present invention, the charge generating agent is not particularly limited, and examples thereof include phthalocyanine-based pigments such as metal-free phthalocyanine, titanyl phthalocyanine (TiOPc), hydroxygallium phthalocyanine, and chlorogallium phthalocyanine, such as disazo pigments, Disazo condensation pigment, monoazo pigment, perylene pigment, dithioketopyrrolopyrrole pigment, metal-free naphthalocyanine pigment, metal naphthalocyanine pigment, squaraine pigment, trisazo pigment, indigo pigment, azulenium pigment, cyanine pigment, pyrylium salt, ansanthrone Examples thereof include pigments, triphenylmethane pigments, selenium pigments, toluidine pigments, pyrazoline pigments, and quinacridone pigments.

The charge generating agent may be variously selected from the above examples so that the electrophotographic photosensitive member has sensitivity in a desired absorption wavelength region. Said charge generating agent may be used independently, and 2 or more types may be mixed and used for it.
In a digital optical image forming apparatus such as a laser beam printer, a semiconductor laser (LD) or a light emitting diode (LED) is generally used as an exposure light source, and the wavelength thereof is a long wavelength region around 680 to 830 nm ( The so-called “near infrared region”) is the mainstream. Therefore, in an electrophotographic photosensitive member used in an image forming apparatus of a digital optical system, it is preferable that the charge generator is a metal-free phthalocyanine, titanyl phthalocyanine, hydroxygallium phthalocyanine, chloro, which has excellent sensitivity in the near infrared region. And phthalocyanine pigments such as gallium phthalocyanine.

  The crystal form of the phthalocyanine pigment is not particularly limited. For example, the metal-free phthalocyanine is preferably X-type or τ-type, and titanyl phthalocyanine is α-type (in the X-ray diffraction spectrum, the Bragg angle ( 2θ ± 0.2 °) having main diffraction peaks at 7.6 ° and 28.6 °) or Y-type (Bragg angle (2θ ± 0.2 °) having main diffraction peaks at 27.2 °) It is preferable that the hydroxygallium phthalocyanine is V type, and the chlorogallium phthalocyanine is preferably II type.

In an analog optical system image forming apparatus using a white light source such as a halogen lamp as an exposure light source, the charge generator is preferably a perylene pigment or a bisazo pigment having sensitivity in the visible region. .
In the electrophotographic photoreceptor of the present invention, the naphthalimide derivative represented by the general formula (1) is contained in the photosensitive layer as an electron transport agent. Examples of the naphthalimide derivative include those similar to those exemplified for the naphthoquinone of the present invention.

  In the electrophotographic photoreceptor of the present invention, the binder resin is not particularly limited, and examples thereof include bisphenol A type, bisphenol F type, bisphenol AD type, bisphenol Z type, bisphenol A type, bisphenol C type, and bisphenol ZC type. Polycarbonate using bisphenol, for example, polyester, polyarylate, polystyrene, poly (meth) acrylic acid ester and the like can be mentioned. Of these, polycarbonate can make the strength and abrasion resistance of the photosensitive layer even better, and is particularly suitable when the photosensitive layer is a single layer type. Moreover, since it has excellent compatibility with the charge transport agent and does not have a site that interferes with the charge transport ability of the charge transport agent in its molecule, it is also suitable for obtaining a highly sensitive electrophotographic photoreceptor. is there.

In the electrophotographic photoreceptor of the present invention, other electron transport agents may be contained as an optional electron transport agent together with the naphthalimide derivative represented by the general formula (1).
Other electron transport agents include, for example, benzoquinone compounds, naphthalimide derivatives, anthraquinone compounds, diphenoquinone compounds, dinaphthalimide derivatives, naphthalene tetracarboxylic acid diimide compounds, fluorenone compounds, malononitrile compounds, thiopyran compounds, Examples include trinitrothioxanthone compounds, dinitroanthracene compounds, dinitroacridine compounds, nitroantharaquinone compounds, dinitroanthraquinone compounds, and the like.

In the electrophotographic photoreceptor of the present invention, the photosensitive layer may contain a hole transporting agent together with the naphthalimide derivative represented by the general formula (1).
Although it does not specifically limit as a hole transport agent, For example, it substitutes for aromatic hydrocarbons, such as benzene, naphthalene, phenanthrene, anthracene, biphenyl, o-, m-, p-terphenyl, binaphthalene, stilbene, styryl stilbene. A compound obtained by substituting 1, 2 or 3 diarylamino groups which may have a group (specifically, for example, N, N, N ′, N′-tetraphenylbenzidine compound, N, N , N ′, N′-tetraphenylphenylenediamine compounds, N, N, N ′, N′-tetraphenylnaphthylenediamine compounds, N, N, N ′, N′-tetraphenylphenanthrenediamine compounds For example, styryl compounds such as 9- (4-diethylaminostyryl) anthracene.), For example, 2,5-di (4-methylamino) Oxadiazole compounds such as phenyl) -1,3,4-oxadiazole, for example, carbazole compounds such as polyvinyl carbazole, for example, pyrazoline compounds such as 1-phenyl-3- (p-dimethylaminophenyl) pyrazoline Examples of the compound include organic polysilane compounds, hydrazone compounds, indole compounds, oxazole compounds, isoxazole compounds, thiazole compounds, thiadiazole compounds, imidazole compounds, pyrazole compounds, and triazole compounds.

The aromatic hydrocarbon may have a substituent such as an alkyl group, a cycloalkyl group, an alkenyl group, an aryl group, an aralkyl group, and an arylalkenyl group.
Examples of the alkyl group, cycloalkyl group, aryl group, and aralkyl group include the same groups as those represented by R ² .
Examples of the alkenyl group include alkenyl groups having 1 to 6 carbon atoms such as vinyl, 1-propenyl, allyl, isopropenyl, 2-butenyl, 1,3-butadienyl, 1-pentenyl, 2-hexenyl and the like.

Examples of the arylalkenyl group include arylalkenyl groups having 8 to 12 carbon atoms such as styryl and cinnamyl.
Examples of the diarylamino group of the diarylamino group which may have a substituent include diphenylamino, dinaphthylamino, dibenzylamino, and distyrylamino.

Examples of the substituent of the diarylamino group which may have a substituent include an alkyl group, a cycloalkyl group, an alkenyl group, an aryl group, an aralkyl group, and an arylalkenyl group. Examples of these substituents include the same groups as those described above.
In the present invention, the photosensitive layer includes a charge generator as an essential component, a naphthalimide derivative (electron transport agent) represented by the above general formula (1), a binder resin, and, if necessary, optional components. In addition to containing other electron transporting agents and hole transporting agents, for example, deterioration of dispersants, sensitizers, for example, antioxidants, radical scavengers, singlet quenchers, ultraviolet absorbers, etc. Inhibitors such as softeners, plasticizers, surface modifiers, extenders, thickeners, dispersion stabilizers, waxes, acceptors, donors such as dispersibility of charge transport agents and charge generators, surface of photosensitive layer A surfactant or leveling agent for improving smoothness can be contained.

Examples of the dispersant include azo pigments such as disazo yellow, dianisidine orange, pyrazolone orange, and pyrazolone red as dispersants for improving the dispersibility of the charge generator in the binder resin. Examples of the sensitizer include terphenyl, halonaphthoquinones, acenaphthylene, and the like.
Among the electrophotographic photoreceptors of the present invention, an electrophotographic photoreceptor having a single-layer photosensitive layer includes, for example, a charge generator, a naphthalimide derivative (electron transport agent) represented by the above general formula (1), and A binder resin and, if necessary, other electron transport agent, hole transport agent and other components are dispersed or dissolved in a dispersion medium, and the thus obtained coating solution for forming a photosensitive layer is used as a conductive substrate. It can be manufactured by coating on top and drying.

  Examples of the dispersion medium include alcohols such as methanol, ethanol, isopropanol, and butanol, aliphatic hydrocarbons such as n-hexane, octane, and cyclohexane, and aromatic hydrocarbons such as benzene, toluene, and xylene. Halogenated hydrocarbons such as dichloromethane, dichloroethane, chloroform, carbon tetrachloride, chlorobenzene, ethers such as dimethyl ether, diethyl ether, tetrahydrofuran, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, such as acetone, methyl ethyl ketone, cyclohexanone, etc. Ketones, for example, esters such as ethyl acetate and methyl acetate, such as dimethylformaldehyde, dimethylformamide, dimethyl Sulfoxide and the like. These dispersion media may be used alone or in combination of two or more.

The photosensitive layer may be formed directly on the conductive substrate or may be formed via an undercoat layer (barrier layer). Further, a protective layer may be formed on the surface of the photoreceptor.
The coating liquid for forming the photosensitive layer is, for example, a charge generator, a charge transport agent, a binder resin, and the like by dispersing and mixing with a dispersion medium using a roll mill, a ball mill, an attritor, a paint shaker, an ultrasonic disperser, and the like. Can be prepared.

In the single-layer type photosensitive layer, the thickness of the photosensitive layer is not particularly limited, but is preferably 5 to 100 μm, and more preferably 10 to 50 μm.
In the single-layer type photosensitive layer, the content ratio of the charge generator is not particularly limited, but is preferably 0.1 to 50 parts by weight, more preferably 0.5 to 30 parts by weight with respect to 100 parts by weight of the binder resin. Part. The content ratio of the naphthalimide derivative represented by the general formula (1) is not particularly limited, but is preferably 5 to 100 parts by weight, more preferably 10 to 80 parts by weight with respect to 100 parts by weight of the binder resin. is there. In the case where the naphthalimide derivative represented by the general formula (1) and another electron transfer agent are used in combination, the proportion of the naphthalimide derivative represented by the general formula (1) in the total amount of both is preferably 5% by weight. % Or more, and more preferably 20% by weight or more. In the case where a hole transport agent is optionally contained, the content ratio of the hole transport agent is not particularly limited, but is preferably 10 to 200 parts by weight, more preferably 20 to 20 parts by weight with respect to 100 parts by weight of the binder resin. 100 parts by weight. Moreover, the total amount of the electron transport agent and the hole transport agent is not particularly limited, but is preferably 20 to 300 parts by weight, and more preferably 30 to 200 parts by weight with respect to 100 parts by weight of the binder resin.

  Among the electrophotographic photosensitive members of the present invention, the electrophotographic photosensitive member having a laminated photosensitive layer includes, for example, a charge generating agent, a binder resin, and, if necessary, a hole transporting agent and other components. Are dispersed or dissolved in a dispersion medium, and the thus obtained charge generation layer forming coating solution is applied onto a conductive substrate and dried to form a charge generation layer. Next, a naphthalimide derivative (electron transport agent) represented by the general formula (1), a binder resin, and, if necessary, another electron transport agent, a hole transport agent, and other components are dispersed in a dispersion medium. The charge transport layer is formed by applying the coating liquid for forming the charge transport layer thus obtained on the charge generation layer and drying it. In this way, an electrophotographic photosensitive member can be produced in which a charge generation layer and a charge transport layer are laminated in this order on a conductive substrate. The stacking order of the charge generation layer and the charge transport layer may be the reverse order of the above case, but in general, the charge generation layer is thin and the strength is not sufficient. The stacking order is preferable.

Examples of the dispersion medium include the same ones as described above.
The charge generation layer or charge transport layer may be formed directly on the conductive substrate, or may be formed via an undercoat layer. Further, a protective layer may be formed on the surface of the photoreceptor.
The coating solution for forming the charge generation layer and the coating solution for forming the charge transport layer include, for example, a predetermined component such as a charge generation agent, a charge transport agent, and a binder resin together with a dispersion medium, a roll mill, a ball mill, an attritor, a paint shaker, It can be prepared by dispersing and mixing using a sonic disperser or the like.

In the laminated photosensitive layer, the thickness of the photosensitive layer is not particularly limited, but the charge generation layer is preferably 0.01 to 5 μm, more preferably 0.1 to 3 μm, and the charge transport layer is preferable. Is 2 to 100 μm, more preferably 5 to 50 μm.
In the charge generation layer of the multilayer photosensitive layer, the content ratio of the charge generation agent is not particularly limited, but is preferably 5 to 1000 parts by weight, more preferably 30 to 500 parts with respect to 100 parts by weight of the binder resin. Parts by weight. In the charge transport layer of the multilayer photosensitive layer, the content of the naphthalimide derivative represented by the general formula (1) is not particularly limited, but is preferably 10 to 500 parts by weight, more preferably 25 to 200. Parts by weight.

  The electrophotographic photosensitive member of the present invention is suitable for image forming apparatuses such as electrostatic copying machines, facsimiles, and laser beam printers, especially for applications that require higher image processing speed and higher image quality. .

EXAMPLES Next, although this invention is demonstrated in detail based on an Example, this invention is not limited by these Examples.
Synthesis example 1

In a 200 ml acetic acid solution of 27 g (0.111 mol) of 4-nitro-1,8-naphthalic anhydride represented by the following formula (8), 15 g (0.111 mol) of an aniline derivative represented by the following formula (7) Was added dropwise and heated under stirring for 4 hours. After completion of the reaction, the reaction solution was cooled, 200 ml of methanol was added thereto and stirred, and the precipitated solid was filtered off. After the obtained solid was dissolved in chloroform and the organic layer was washed with water, anhydrous sodium sulfate and activated clay were added to the organic layer, followed by drying and adsorption treatment. Chloroform was distilled off under reduced pressure, and the resulting residue was recrystallized from chloroform to obtain a solid represented by the following formula (9). See the following reaction formula (i).
Compound (9): yellow crystals, yield 31.8 g, yield 79.5%
Next, after stirring a 1 L flask containing 200 ml of tetrahydrofuran and 2.78 g (0.0733 mol) of LiAlH ₄ under an argon atmosphere for 30 minutes, 22 g of the compound (9) obtained by the above reaction formula (i) ( 0.0611 mol) in THF was added dropwise and stirred at 0 ° C. for 2 hours.
After completion of the reaction, the reaction solution was poured into water, extracted with chloroform, the organic layer was washed with water, the organic layer was dried over anhydrous sodium sulfate, and the solvent was distilled off. The obtained residue was purified by column chromatography (chloroform development) to obtain a compound represented by the following formula (10). See the following reaction formula (ii).
Compound (10): pale yellow crystals Yield 15.8 g, Yield 78.3%
Next, in a 500 ml flask containing 5.5 g (0.0303 mol) of benzophenone represented by the following formula (11) and 100 ml of acetic acid, compound (10) (10 g (0.0303 mol) obtained by the above formula (ii) was placed. A solution of 150 ml of acetic acid was added dropwise and heated and refluxed for 4 hours After the reaction was completed, the reaction solution was cooled, 200 ml of methanol was added thereto, and the precipitated solid was filtered and dissolved in chloroform. The obtained chloroform solution was washed with water, and anhydrous sodium sulfate and activated clay were added to the organic layer, followed by drying and adsorption treatment.After the chloroform was distilled off under reduced pressure, the residue was recrystallized with chloroform, and the resulting crystals were obtained. By drying, a compound represented by the following formula (1-1) was obtained, see the following reaction formula (iii).
Compound (11-1): Yellow crystals Yield 12.2 g, Yield 81.0%

Synthesis example 2
Synthesis example except that 7.0 g (0.0303 mol) of a carbonyl derivative represented by the following formula (12) was used in place of benzophenone (11) in the reaction represented by the reaction formula (iii) of Synthesis Example 1 above. The synthesis reaction was carried out in the same manner as in Example 1 to obtain a naphthalimide derivative represented by the following formula (1-2).
See the following reaction formula (iv).
Compound (1-2): Yellow crystals Yield 13.3 g, Yield 80.4%

Synthesis example 3
In the reaction shown in the reaction formula (iii) of the synthesis example 1, except that 6.9 g (0.0303 mol) of 4-nitrobenzophenone represented by the following formula (13) was used instead of benzophenone (11), A synthesis reaction was carried out in the same manner as in Synthesis Example 1 to obtain a naphthalimide derivative represented by the following formula (1-3).
See the following reaction formula (iv).
Compound (1-3): Yellow crystals Yield 13.1 g, Yield 80.1%

Example 1
5 parts by weight of an X-type metal-free phthalocyanine (charge generating agent), 20 parts by weight of a naphthalimide derivative (electron transporting agent) represented by the above formula (1-1), and N, represented by the following formula (HT-1) 60 parts by weight of N, N ′, N′-tetra (3,4-xylyl) -1,3-phenylenediamine (hole transport agent), 100 parts by weight of Z-type polycarbonate (binder resin), and tetrahydrofuran (solvent) ) 800 parts by weight were mixed and dispersed in a ball mill for 50 hours to obtain a coating solution for a single-layer type photosensitive layer.

  Next, this coating solution is applied on an aluminum base tube (conductive substrate) by a dip coating method and dried with hot air at 100 ° C. for 30 minutes, thereby providing an electronic device having a single-layer type photosensitive layer with a thickness of 25 μm. A photographic photoreceptor was obtained.

Example 2
In the same manner as in Example 1 except that 20 parts by weight of the naphthalimide derivative represented by the above formula (1-2) was used instead of the naphthalimide derivative represented by the above formula (1-1), the film thickness was changed. An electrophotographic photosensitive member having a single-layer type photosensitive layer of 25 μm was obtained.
Example 3
In the same manner as in Example 1, except that 20 parts by weight of the naphthalimide derivative represented by the above formula (1-3) was used instead of the naphthalimide derivative represented by the above formula (1-1), the film thickness was changed. An electrophotographic photosensitive member having a single-layer type photosensitive layer of 25 μm was obtained.

Comparative Example 1
In the same manner as in Example 1, except that 20 parts by weight of the naphthalimide derivative represented by the following formula (ET-1) was used instead of the naphthalimide derivative represented by the above formula (1-1), the film thickness An electrophotographic photosensitive member having a single-layer type photosensitive layer of 25 μm was obtained.

Comparative Example 2
In the same manner as in Example 1, except that 20 parts by weight of the naphthalimide derivative represented by the following formula (ET-2) was used instead of the naphthalimide derivative represented by the above formula (1-1), the film thickness An electrophotographic photosensitive member having a single-layer type photosensitive layer of 25 μm was obtained.
Comparative Example 3
In the same manner as in Example 1, except that 20 parts by weight of the naphthalimide derivative represented by the following formula (ET-3) was used instead of the naphthalimide derivative represented by the above formula (1-1), the film thickness An electrophotographic photosensitive member having a single-layer type photosensitive layer of 25 μm was obtained.

Sensitivity characteristic test The sensitivity of the electrophotographic photoreceptors obtained in Examples 1 to 3 and Comparative Examples 1 to 3 was measured using a drum sensitivity tester manufactured by GENTEC.
In this sensitivity characteristic test, first, an applied voltage is applied to the surface of the photoconductor to charge the surface potential (initial surface potential V ₀ ) to +700 V, and then a band from white light from a halogen lamp (exposure light source) is used. Monochromatic light (half-width 20 nm, light intensity 1.5 μJ · cm ⁻² ) with a wavelength of 780 nm taken out using a pass filter was irradiated on the surface of the photoreceptor. Next, the surface potential at the time when 0.5 seconds had elapsed from the start of exposure was measured and set as the residual potential _Vr . Further, the exposure amount (μJ / cm ² ) until the surface potential of the photoconductor is reduced to half the pre-exposure potential (Vo), that is, the half exposure amount E _1/2 (μJ / cm ² ) It was measured.

  Table 1 shows the measurement results of the sensitivity characteristic test.

“Crystallation” indicates that the measurement could not be performed due to crystallization.

Example 4
Instead of N, N, N ′, N′-tetra (3,4-xylyl) -1,3-phenylenediamine, bis-1,4- [4 ′-[represented by the following formula (HT-2) N- (2 ″ -ethyl-6 ″ -methyl) phenyl-Nm-tolyl] amino-2′-methylstyryl] benzene was used in the same manner as in Example 1 except that 60 parts by weight of benzene was used. An electrophotographic photosensitive member having a single-layer type photosensitive layer having a thickness of 25 μm was obtained.

Example 5
In the same manner as in Example 4 except that 20 parts by weight of the naphthalimide derivative represented by the above formula (1-2) was used instead of the naphthalimide derivative represented by the above formula (1-1), the film thickness was changed. An electrophotographic photosensitive member having a single-layer type photosensitive layer of 25 μm was obtained.
Example 6
In the same manner as in Example 4, except that 20 parts by weight of the naphthalimide derivative represented by the above formula (1-3) was used instead of the naphthalimide derivative represented by the above formula (1-1), the film thickness was changed. An electrophotographic photosensitive member having a single-layer type photosensitive layer of 25 μm was obtained.

Comparative Example 4
In the same manner as in Example 4, except that 20 parts by weight of the naphthalimide derivative represented by the above formula (ET-1) was used instead of the naphthalimide derivative represented by the above formula (1-1), the film thickness was changed. An electrophotographic photosensitive member having a single-layer type photosensitive layer of 25 μm was obtained.
Comparative Example 5
In the same manner as in Example 4 except that 20 parts by weight of the naphthalimide derivative represented by the above formula (ET-2) was used instead of the naphthalimide derivative represented by the above formula (1-1), the film thickness was changed. An electrophotographic photosensitive member having a single-layer type photosensitive layer of 25 μm was obtained.

  The electrophotographic photoreceptors obtained in Examples 4 to 6 and Comparative Examples 4 and 5 were subjected to sensitivity characteristic tests in the same manner as described above. The results are shown in Table 2.

“Crystallation” indicates that the measurement could not be performed due to crystallization.

Example 7
Instead of N, N, N ′, N′-tetra (3,4-xylyl) -1,3-phenylenediamine, bis-1,2- [4 ′-[represented by the following formula (HT-3) N, N-di (p-tolyl)] aminostyryl] benzene is used in the same manner as in Example 1 except that 60 parts by weight of benzene is used to obtain an electrophotographic photosensitive member having a single-layer photosensitive layer having a thickness of 25 μm. It was.

Example 8
In the same manner as in Example 7, except that 20 parts by weight of the naphthalimide derivative represented by the above formula (1-2) was used instead of the naphthalimide derivative represented by the above formula (1-1), the film thickness was changed. An electrophotographic photosensitive member having a single-layer type photosensitive layer of 25 μm was obtained.
Example 9
In the same manner as in Example 7, except that 20 parts by weight of the naphthalimide derivative represented by the above formula (1-3) was used instead of the naphthalimide derivative represented by the above formula (1-1), the film thickness was changed. An electrophotographic photosensitive member having a single-layer type photosensitive layer of 25 μm was obtained.
Comparative Example 6
In the same manner as in Example 7, except that 20 parts by weight of the naphthalimide derivative represented by the above formula (ET-1) was used instead of the naphthalimide derivative represented by the above formula (1-1), the film thickness was changed. An electrophotographic photosensitive member having a single-layer type photosensitive layer of 25 μm was obtained.
Comparative Example 7
In the same manner as in Example 7, except that 20 parts by weight of the naphthalimide derivative represented by the above formula (ET-2) was used instead of the naphthalimide derivative represented by the above formula (1-1), the film thickness was changed. An electrophotographic photosensitive member having a single-layer type photosensitive layer of 25 μm was obtained.

  The electrophotographic photoreceptors obtained in Examples 7 to 9 and Comparative Examples 6 and 7 were subjected to sensitivity characteristic tests in the same manner as described above. The results are shown in Table 3.

“Crystallation” indicates that the measurement could not be performed due to crystallization.

As apparent from Tables 1 to 3, when the naphthalimide derivative represented by the general formula (1) was used as an electron transporting agent, an electrophotographic photoreceptor excellent in electrical characteristics could be obtained.
The present invention is not limited to the above description, and various design changes can be made within the scope of the matters described in the claims.

Claims (3)

A naphthalimide derivative represented by the following general formula (1):
(R _{1 to} R ₃ are optionally substituted alkyl groups having 1 to 6 carbon atoms, alkoxy groups having 1 to 6 carbon atoms, cycloalkyl groups having 3 to 8 carbon atoms, and 6 to 20 carbon atoms. An aryl group and an aralkyl group having 7 to 18 carbon atoms, R ₄ and R _{5 each} represent an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 20 carbon atoms which may have a substituent.)   An electrophotographic photoreceptor comprising the compound according to claim 1.   The electrophotographic photosensitive member according to claim 2, wherein the photosensitive layer is a single layer type.