JP2002123013A - Electrophotographic photoreceptor, benzofuran styryl compound to be used for the same, and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrophotographic photoreceptor having high sensitivity and high durability, to provide a new benzofuran-styryl compound having a benzo[b] furan skeleton as the mother nucleus to be used as a charge transfer material of the photoreceptor, and to provide a method for manufacturing the photoreceptor with high efficiency. SOLUTION: In the electrophotographic photoreceptor, a photosensitive layer 4 formed on a conductive supporting body 1 contains a new benzofuran-styryl compound having a benzofuran skeleton as the mother nucleus as the charge transfer material 3. The new benzofuran-styryl compound is prepared by the reaction of a benzo[b]furan aldehyde compound and a phosphorus reagent.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an electrophotographic photoreceptor used in an electrophotographic process, a benzofuran-styryl compound suitably used for the electrophotographic photoreceptor, and a method for producing the same.

[0002]

2. Description of the Related Art In recent years, electrophotography technology has been used in various printer fields as well as in the field of copiers, since it has immediacy and can provide high-quality images. I have. In the field of electrophotographic photoreceptors (hereinafter also simply referred to as “photoreceptors”), as photoconductive materials, inorganic materials such as selenium, arsenic, selenium alloys, selenium-tellurium alloys, cadmium sulfide and zinc oxide have been used. Material was used. However, in recent years, instead of such inorganic materials, an organic photoreceptor mainly composed of an organic photoconductive material having advantages such as no pollution, good film formability and ease of production has been developed. It became so.

[0003] Among organic photoconductors, a so-called stacked type photoconductor in which a charge generation layer composed of a charge generation material and a charge transfer layer composed of a charge transfer material are sequentially laminated has been devised. It has become. That is, in the laminated photoreceptor, by combining a charge generation material capable of efficiently forming a desired charge generation layer and a charge transfer material capable of efficiently forming a desired charge transfer layer, 1. A higher sensitivity photoconductor can be obtained; 2. A wide range of materials can be selected, and a highly safe photoreceptor can be obtained; Photoreceptors have become the mainstream because of their high coating productivity and relatively low cost. Copiers having high printing durability and high-speed performance, such as a printing durability of 200,000 copies or more and a copying speed per minute of 70 or more, are commercially available.

As described above, some of the organic laminated photoconductors that have been put into practical use so far have excellent performance, but most of them are related to photoconductor production in pursuit of the performance. At present, various problems still exist.

[0005] Among those specific problems, some related to charge transfer materials are listed as follows. 1. low compatibility with the binder polymer; 2. easy precipitation of crystals; 3. changes in sensitivity when used repeatedly; 4. poor chargeability and repetition characteristics; Poor residual potential characteristics;

[0006] A typical one of such charge transfer materials is classified according to its structural characteristics. First, an arylene group (mostly a phenylene group in the early stage of its development) was initially used. A hydrazone type having a central nucleus (JP-A-54-59143) and a stilbene-styryl type (JP-A-58-1980)
No. 43 gazette) and triarylamines (JP-B-58)
No. 32372) has been energetically studied. afterwards,
A series of compounds having a monocyclic heterocyclic ring at its central nucleus, phenothiazines, triazoles, quinoxalines, oxadiazoles, oxazoles, pyrazolines, dihydronicotinamide compounds, indoline compounds and semicarbazone compounds Began to be developed. Recently, pyrene derivatives, naphthalene derivatives, phenanthrene derivatives (JP-A-5-148209) and the like having a condensed polycyclic hydrocarbon system at its central nucleus have been developed.

[0007]

As described above, although a large number of organic compounds have been developed as charge transfer materials, none of the organic compounds satisfy all of the above-mentioned problems. At present, those which sufficiently satisfy the required basic properties, as well as the mechanical strength and high durability, have not yet been obtained.

In the case of a phenanthrene derivative, when synthesizing the derivative: 1. The phenanthrene-9-carbaldehyde, which is assumed to be a starting material, is very expensive; Compounds in which two identical side chains have been introduced as by-products when the first side chain is introduced, since the connecting parts of the mother nucleus for sequentially introducing the hydrazone part and the styryl part are both the same aldehyde group. Are generated, and it takes time to purify the compound, and the reaction yield is reduced, and various problems are pointed out.

An object of the present invention is to provide an electrophotographic photoreceptor having high sensitivity and high durability, a novel benzofuran-styryl compound having a benzo [b] furan skeleton used as a charge transfer material thereof, and its efficiency. To provide a good manufacturing method.

[0010]

According to the present invention, a benzofuran-styryl compound represented by the following general formula (I) is contained as a charge transfer material in a photosensitive layer provided on a conductive support. An electrophotographic photoreceptor characterized by the following:

[0011]

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(Wherein, Ar ₁ represents an arylene group which may have a substituent or a divalent heterocyclic group which may have a substituent. Ar ₂ is an aryl group which may have a substituent or a substituent. A heterocyclic group which may be contained or an aralkyl group which may contain a substituent, wherein Ar ₃ and Ar ₄ each include an aryl group which may contain a substituent, a heterocyclic group which may contain a substituent, and a substituent Represents an aralkyl group which may have a substituent, an alkyl group having 1 to 3 carbon atoms which may have a substituent or a hydrogen atom, and a represents an alkyl group having 1 to 5 carbon atoms which may have a substituent or carbon atom which may have a substituent. A fluoroalkyl group having 1 to 5, a perfluoroalkyl group having 1 to 5 carbon atoms which may contain a substituent, an alkoxy group having 1 to 3 carbon atoms,
It represents a dialkylamino group having 1 to 3 carbon atoms, a halogen atom or a hydrogen atom, and n represents an integer of 1 to 4. Where n
Is 2 or more, a plurality of a may be the same or different;
They may form a ring with each other. )

According to the present invention, an electrophotographic photosensitive member having high sensitivity and high durability can be provided by containing a benzofuran-styryl compound represented by the general formula (I) as a charge transfer material. That is, since the benzofuran-styryl compound has a wide conjugated system, the charge mobility can be increased to improve the residual potential characteristics of the electrophotographic photoreceptor. Further, since the benzofuran-styryl compound has excellent compatibility with the binder polymer, it can be contained in a large amount in the photosensitive layer to improve the photosensitivity of the electrophotographic photosensitive member. Further, since the benzofuran-styryl compound hardly precipitates as crystals, the characteristics of the electrophotographic photoreceptor when used repeatedly can be stabilized.

Further, the present invention is characterized in that the benzofuran-styryl compound is a compound represented by the following general formula (II).

[0015]

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Wherein b is an alkyl group having 1 to 5 carbon atoms which may have a substituent, and 1 to 3 carbon atoms which may have a substituent.
5 represents a fluoroalkyl group, a perfluoroalkyl group having 1 to 5 carbon atoms which may contain a substituent, an alkoxy group having 1 to 3 carbon atoms, a dialkylamino group having 1 to 3 carbon atoms, a halogen atom or a hydrogen atom, m shows the integer of 1-4. However, when m is 2 or more, a plurality of b may be the same or different. Ar ₂ , Ar ₃ , Ar ₄ , a and n have the same meanings as those shown in formula (I). )

According to the present invention, the benzofuran-styryl compound represented by the general formula (II) having the same properties as the general formula (I) is contained as a charge transfer material, thereby having high sensitivity and high durability. An electrophotographic photoreceptor can be provided.

Further, the present invention is characterized in that the benzofuran-styryl compound is a compound represented by the following general formula (III).

[0019]

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(In the formula, d is an alkyl group having 1 to 5 carbon atoms which may have a substituent, 1 to 5 carbon atoms which may have a substituent.
5 represents a fluoroalkyl group, a perfluoroalkyl group having 1 to 5 carbon atoms which may contain a substituent, an alkoxy group having 1 to 3 carbon atoms, a dialkylamino group having 1 to 3 carbon atoms, a halogen atom or a hydrogen atom, l represents an integer of 1 to 5. However, when 1 is 2 or more, a plurality of d may be the same or different. Ar ₃ , Ar ₄ , a, b, n and m have the same meanings as those shown in formula (II). )

According to the present invention, the benzofuran-styryl compound represented by the general formula (III) having the same properties as the general formula (I) is contained as a charge transfer material, thereby having high sensitivity and high durability. An electrophotographic photoreceptor can be provided.

Further, the present invention is characterized in that the benzofuran-styryl compound is a compound represented by the following general formula (IV).

[0023]

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(Wherein, e is an alkyl group having 1 to 5 carbon atoms which may have a substituent, and 1 to 5 carbon atoms which may have a substituent.)
5 represents a fluoroalkyl group, a perfluoroalkyl group having 1 to 5 carbon atoms which may contain a substituent, an alkoxy group having 1 to 3 carbon atoms, a dialkylamino group having 1 to 3 carbon atoms, a halogen atom or a hydrogen atom, k represents an integer of 1 to 5. However, when k is 2 or more, a plurality of e may be the same or different. Ar ₃ , Ar ₄ , a, b, n and m have the same meanings as those shown in formula (III). )

According to the present invention, the benzofuran-styryl compound represented by the general formula (IV) having the same properties as the general formula (I) is contained as a charge transfer material, whereby high sensitivity and high durability are obtained. An electrophotographic photoreceptor can be provided.

Further, the present invention is characterized in that the photosensitive layer has a laminated structure of a charge generation layer containing a charge generation material and a charge transfer layer containing the charge transfer material.

According to the present invention, the charge-transfer layer of the photosensitive layer having a laminated structure contains the benzofuran-styryl compound as a charge-transfer substance, so that a laminated electrophotographic photosensitive member having high sensitivity and high durability can be obtained. Can be provided.

Further, the invention is characterized in that the photosensitive layer comprises a single layer containing a charge generating substance and the charge transfer substance.

According to the present invention, by including the benzofuran-styryl compound as a charge transfer material in a single photosensitive layer, a single-layer electrophotographic photosensitive member having excellent sensitivity and repetition characteristics even in positive charging. Body can be provided.

The present invention is a benzofuran-styryl compound represented by the following general formula (I).

[0031]

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(Wherein, Ar ₁ represents an arylene group which may have a substituent or a divalent heterocyclic group which may have a substituent. Ar ₂ is an aryl group which may have a substituent or a substituent. A heterocyclic group which may be contained or an aralkyl group which may contain a substituent, wherein Ar ₃ and Ar ₄ each include an aryl group which may contain a substituent, a heterocyclic group which may contain a substituent, and a substituent Represents an aralkyl group which may have a substituent, an alkyl group having 1 to 3 carbon atoms which may have a substituent or a hydrogen atom, and a represents an alkyl group having 1 to 5 carbon atoms which may have a substituent or carbon atom which may have a substituent. A fluoroalkyl group having 1 to 5, a perfluoroalkyl group having 1 to 5 carbon atoms which may contain a substituent, an alkoxy group having 1 to 3 carbon atoms,
It represents a dialkylamino group having 1 to 3 carbon atoms, a halogen atom or a hydrogen atom, and n represents an integer of 1 to 4. Where n
Is 2 or more, a plurality of a may be the same or different;
They may form a ring with each other. )

According to the present invention, the benzofuran-styryl compound represented by the general formula (I) has a wide conjugated system,
A compound which is excellent in compatibility with a binder polymer and hardly precipitates as a crystal can provide a compound which can be used as a charge transfer material for an electrophotographic photosensitive member having high sensitivity and high durability. . That is, if the benzofuran-styryl compound is used as a charge transfer material for an electrophotographic photoreceptor, it has a wide conjugated system, so that the charge mobility can be increased and the residual potential characteristics of the electrophotographic photoreceptor can be improved. In addition, due to its excellent compatibility with the binder polymer, the photosensitivity of the electrophotographic photoreceptor can be improved by containing a large amount in the photosensitive layer. Further, the characteristics of the electrophotographic photoreceptor at the time of repeated use can be stabilized by being hardly precipitated as crystals.

In the present invention, a benzo [b] furanaldehyde compound represented by the following general formula (V) is reacted with a phosphorus reagent represented by the following general formula (VI) to obtain a compound represented by the following general formula (I). A method for producing a benzofuran-styryl compound, which comprises producing the benzofuran-styryl compound shown below.

[0035]

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(Wherein, Ar ₁ represents an arylene group which may have a substituent or a divalent heterocyclic group which may have a substituent. Ar ₂ is an aryl group which may have a substituent or a substituent. A heterocyclic group which may be contained or an aralkyl group which may contain a substituent, wherein Ar ₃ and Ar ₄ each include an aryl group which may contain a substituent, a heterocyclic group which may contain a substituent, and a substituent Represents an aralkyl group which may have a substituent, an alkyl group having 1 to 3 carbon atoms which may have a substituent or a hydrogen atom, and a represents an alkyl group having 1 to 5 carbon atoms which may have a substituent or carbon atom which may have a substituent. A fluoroalkyl group having 1 to 5, a perfluoroalkyl group having 1 to 5 carbon atoms which may contain a substituent, an alkoxy group having 1 to 3 carbon atoms,
It represents a dialkylamino group having 1 to 3 carbon atoms, a halogen atom or a hydrogen atom, and n represents an integer of 1 to 4. Where n
Is 2 or more, a plurality of a may be the same or different;
They may form a ring with each other. )

[0037]

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(In the formula (V), Ar ₁ , Ar ₂ , a and n
Has the same meaning as that shown in the general formula (I).

[0039]

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(In the formula (VI), Ar ₃ and Ar ₄ have the same meanings as those shown in the general formula (I). Ar
₅ is an aryl group which may have a substituent, an aralkyl group which may have a substituent, or an alkyl group having 1 to 3 carbon atoms which may have a substituent.

According to the present invention, by reacting the benzo [b] furanaldehyde compound with a phosphorus reagent, a benzofuran-styryl compound which is excellent as a charge transfer material for an electrophotographic photoreceptor can be produced very easily in high yield. Can be manufactured.

[0042]

Embodiments of the present invention will be described below.

The benzofuran-styryl compound according to the present invention is represented by the following general formula (I).

[0044]

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In the general formula (I), Ar ₁ represents an arylene group which may have a substituent or a divalent heterocyclic group which may have a substituent.

Specific examples of Ar ₁ include a phenylene group,
Examples include a naphthylene group and a pyridylene group.

In the general formula (I), Ar ₂ represents an aryl group which may have a substituent, a heterocyclic group which may have a substituent, or an aralkyl group which may have a substituent.

Specific examples of Ar ₂ include aryl groups such as phenyl, tolyl, methoxyphenyl, naphthyl, pyrenyl and biphenyl; heterocyclic groups such as benzofuryl, benzothiazolyl, benzoxazolyl and N-ethylenecarbazolyl; And aralkyl groups such as benzyl, methoxybenzyl and 2-thienylmethyl.

In the general formula (I), Ar ₃ and Ar
₄ is an aryl group which may have a substituent, a heterocyclic group which may have a substituent, an aralkyl group which may have a substituent, an alkyl group having 1 to 5 carbon atoms which may have a substituent,
A fluoroalkyl group having 1 to 5 carbon atoms which may have a substituent, a perfluoroalkyl group having 1 to 5 carbon atoms which may have a substituent or a hydrogen atom.

Specific examples of Ar ₃ and Ar ₄ include aryl groups such as phenyl, tolyl, methoxyphenyl, naphthyl, pyrenyl and biphenyl, and heterocyclic rings such as benzofuryl, benzothiazolyl, benzoxazolyl and N-ethylcarbazolyl. Groups, aralkyl groups such as methylbenzyl, methoxybenzyl and 2-thienylmethyl, alkyl groups such as methyl, ethyl and n-propyl, perfluoroalkyl groups such as trifluoromethyl, and 1,1,1-trifluoroethyl and the like Or a hydrogen atom.

In the general formula (I), a represents an alkyl group having 1 to 3 carbon atoms which may have a substituent, a fluoroalkyl group having 1 to 5 carbon atoms which may have a substituent, or a substituent. A perfluoroalkyl group having 1 to 5 carbon atoms,
It represents an alkoxy group having 1 to 3 carbon atoms, a dialkylamino group having 1 to 3 carbon atoms, a halogen atom or a hydrogen atom.

Specific examples of a include methyl, ethyl, n
-Alkyl groups such as propyl and isopropyl, alkoxy groups such as methoxy, ethoxy, n-propoxy and isopropoxy, dialkylamino groups such as dimethylamino, diethylamino and diisopropylamino, and halogen atoms such as fluorine, chlorine and bromine. Can be Generally, electron donating substituents are preferred.

In the general formula (I), n is 1,
2, 3 or 4 is indicated. However, when n is 2 or more, the above-mentioned a may be the same as or different from a plurality of a, and may form a ring with each other.

In particular, among the benzofuran-styryl compounds represented by the general formula (I), Ar ₁ is preferably a phenylene group, which is excellent from the viewpoints of electrophotographic characteristics, cost, production and the like when used in an electrophotographic photosensitive member. or a naphthylene group, Ar ₂ is a phenyl group, p- methylphenyl or naphthyl group, the Ar3 and Ar4, one is a phenyl group, p- methylphenyl group or naphthyl group, the other is a hydrogen atom or both phenyl groups or, p- Methylphenyl groups and those in which a is a hydrogen atom are mentioned.

Specific examples of the benzofuran-styryl compound of the present invention represented by the general formula (I) include, for example, benzofuran-styryl compounds having the structures shown in Tables 1 to 3 below. The benzofuran-styryl compounds according to the invention are not limited.

[0056]

[Table 1]

[0057]

[Table 2]

[0058]

[Table 3]

The benzofuran-styryl compound according to the present invention can be easily produced, for example, as follows.

First, a benzo [b] furanaldehyde compound represented by the following general formula (V) and a compound represented by the following general formula (VI)
The benzofuran-styryl compound according to the present invention can be synthesized by reacting with a phosphorus reagent represented by the formula under basic conditions.

[0061]

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[0062]

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In the general formula (V), Ar ₁ , Ar ₂ , a and n have the same meanings as those in the general formula (I).

In the general formula (VI), Ar ₃ and Ar ₄ are
It has the same meaning as that shown in the general formula (I). Ar ₅
Represents an aryl group which may have a substituent, an aralkyl group which may have a substituent, or an alkyl group having 1 to 3 carbon atoms which may have a substituent.

The reaction under the basic conditions is carried out by, for example, dissolving 1.0 equivalent of a formylbenzo [b] furan compound represented by the above general formula (V) in a solvent such as diethyl ether, tetrahydrofuran, ethylene glycol, dimethyl ether and dimethyl sulfoxide. And the general formula (VI)
And 1.0 to 1.5 equivalents of a phosphorus alkoxide base such as potassium-t-butoxide and sodium ethoxide,
Heating and stirring are performed at room temperature to 60 ° C for 2 to 8 hours.

The electrophotographic photoreceptor according to the present invention contains at least one kind of the above-mentioned benzofuran-styryl compound as a charge transfer material of the photosensitive layer, and optionally, a styryl compound, a hydrazone compound and a trialkyl compound as other charge transfer materials. It may contain a phenylamine compound or the like. Examples of the styryl compound include β-phenyl- [4-
(Benzylamino)] stilbene, β-phenyl- [4
-(N-ethyl-N-phenylamino)] stilbene and 1,1-bis (4-diethylaminophenyl)-
4,4-diphenylbutadiene and the like. Examples of the hydrazone compound include 4- (dibenzylamino) benzaldehyde-N, N-diphenylhydrazone and 4- (ethylphenylamino) benzaldehyde-
N, N-diphenylhydrazone, 4- (N, N-bis (p-tolyl) amino) benzaldehyde-N, N-diphenylhydrazone and 3,3-bis- (4′-diethylaminophenyl) -acrolein-N, N -Diphenylhydrazone and the like. As the triphenylamine compound, for example, 4-methoxy-4 ′-(4-
Methoxystyryl) triphenylamine and 4-methoxy-4'-styryltriphenylamine.

The layer constitution of the electrophotographic photosensitive member according to the present invention is as follows.
Various modes as shown below can be adopted.

FIG. 1 is a cross-sectional view schematically showing an example of an electrophotographic photosensitive member having a function-separated type photosensitive layer having a charge transfer layer 6 on a charge generation layer 5. A charge generation layer 5 having a charge generation material 2 as a main component dispersed in a binder polymer as a photosensitive layer 4 on a conductive support 1 and a charge transfer having a charge transfer material 3 as a main component dispersed in a binder polymer. This is a function-separated type photoconductor comprising a layer 6 and a layer 6. The charge transfer layer 6 is formed on the surface of the charge generation layer 5, and the charge transfer layer 6 contains the benzofuran-styryl compound according to the present invention as the charge transfer substance 3.

FIG. 2 shows a function-separated type photosensitive layer having the charge generation layer 5 on the charge transfer layer 6. 1 is a function-separated type photoreceptor formed by laminating a charge generation layer 5 and a charge transfer layer 6 similar to those in FIG. 1, but the charge generation layer 5 is formed on the surface of the charge transfer layer 6 in reverse to FIG. The charge transfer layer 6 contains the benzofuran-styryl compound according to the present invention as the charge transfer substance 3.

FIG. 3 is a sectional view schematically showing an example of an electrophotographic photosensitive member having a dispersion type photosensitive layer. The structure of a single-layer type photoreceptor comprising a single layer in which a charge generation layer 2 and a charge transfer layer substance 3 are dispersed in a binder as a photosensitive layer 4 on a conductive support 1 is shown.

FIG. 4 is a cross-sectional view showing an example having a surface protective layer 7 in the electrophotographic photosensitive member of FIG. The surface protective layer 7 is provided on the conductive support 1 and the photosensitive layer 14 similar to that shown in FIG.

FIG. 5 is a cross-sectional view showing an example having the intermediate layer 8 in the electrophotographic photosensitive member of FIG. Conductive support 1
An intermediate layer 8 is provided between the photosensitive layer 4 and the photosensitive layer 4 similar to that shown in FIG.

Various methods are conceivable for using the above-mentioned benzofuran-styryl compound in an electrophotographic photosensitive member.
For example, as shown in FIG. 1, in the form of a laminated structure including a charge generation layer 5 and a charge transfer layer 6 having high charge generation efficiency,
A charge generating layer 5 mainly composed of a sensitizing dye, an azo pigment and a phthalocyanine pigment is typically provided on the conductive support 1. A lamination comprising a charge transfer layer formed by dissolving or dispersing the above-mentioned benzofuran-styryl compound in the binder polymer by adding an antioxidant or an electron-withdrawing compound as necessary to the charge generation layer 5. Function-separated type photoreceptor. Further, the above-mentioned benzofuran-styryl compound and a sensitizing dye were added with a chemical sensitizer or an electron-withdrawing compound as required, and dissolved or dispersed in a binder polymer, as shown in FIG. A single-layer photoreceptor formed by coating on the conductive support 1 is obtained. Thus, the benzofuran-styryl compound according to the present invention can be applied to any of these cases.

In preparing a photoreceptor using the benzofuran-styryl compound according to the present invention, a metal drum,
Coating with the help of a binder polymer on a support such as a metal plate, electrically treated paper and a plastic film. In this case, to further increase the sensitivity,
It is desirable to add a sensitizer and a substance that imparts plasticity to the binder polymer as described later to form a uniform photoreceptor coating.

As the binder polymer, various binder polymers can be used depending on the field of use. That is, in the field of photoconductors for copying machines or printers, polystyrene resins, polyvinyl acetal resins, polysulfone resins, polycarbonate resins, polyphenylene oxide resins, polyester resins, alkyd resins, polyarylate resins, and the like are desirable. These resins may be used alone or in combination of two or more. In particular, polystyrene resin, polycarbonate resin, polyarylate resin, polyphenylene oxide resin, and the like have a volume resistance of 10 ¹³ Ω or more, and are excellent in film properties and potential characteristics.

The amount of the binder polymer to be added is preferably 0.2 to 20 times the weight ratio of the above-mentioned benzofuran-styryl compound, and more preferably 0.1 to 20 times.
The range is 5 to 5 times. When the ratio is less than 0.2 times, there is a disadvantage that the benzofuran-styryl compound precipitates from the surface of the photoreceptor, and when the ratio exceeds 20 times, the sensitivity is remarkably reduced.

For use in a printing plate, an alkaline binder polymer is particularly necessary. The alkaline binder polymer is a polymer substance having an acidic group that is soluble in an alcoholic alkaline solvent containing water or a mixed system with water. Examples of the soluble acidic group include an acid anhydride group, a carboxyl group, a phenolic hydroxyl group, a sulfonic acid group, a sulfonamide group and a sulfonimide group. These alkaline binder polymers usually have an acid value of 10
It is preferable to have a high value of 0 or more. A binder polymer having a large acid value is easily dissolved or easily lubricated in an alkaline solvent. As such a binder polymer,
For example, styrene: maleic anhydride copolymer, vinyl acetate: maleic anhydride copolymer, vinyl acetate: crotonic acid copolymer, methacrylic acid: methacrylic acid ester copolymer, phenol resin and methacrylic acid: styrene: methacrylic acid ester And copolymers. These resins are added to the photoconductive organic substance at the same ratio as in the case of a photoconductor of a copying machine.

Examples of the sensitizing dye include triphenylmethane dyes represented by methyl violet, crystal violet, night blue and Victoria blue, erythrosine, rhodamine B, rhodamine 3R, acridine represented by acridine orange and flapeosin and the like. Dyes, thiazine dyes typified by methylene blue and methylene green, oxazine dyes typified by capri blue and meldra blue, and other thiane dyes, styryl dyes, pyrylium salt dyes, and thiopyrylium salt dyes.

In the photosensitive layer, photoconductive pigments that generate electric charges with extremely high efficiency by light absorption include phthalocyanine pigments such as various metal phthalocyanines, metal-free phthalocyanines and halogen-free metal phthalocyanines, peryleneimide and perylene acid. Perylene acid pigments such as anhydrides, azo pigments such as bisazo pigments and trisazo pigments, and other quinacridone pigments,
And anthraquinone pigments. In particular, pigments that generate electric charges, metal-free phthalocyanine pigments, titanyl phthalocyanine pigments, bisazo pigments containing a fluorene or fluorenone ring, bisazo pigments composed of aromatic amines,
Those using a trisazo pigment give an excellent electrophotographic photoreceptor exhibiting high sensitivity.

The sensitizing dye may be used as a charge generating substance. The aforementioned dyes may be used alone,
In many cases, electric charges are generated with higher efficiency by coexisting pigments.

In addition to the above-described ring-enhancing agent, it is necessary to add various chemical substances for the purpose of preventing an increase in residual potential, a decrease in charge potential, a decrease in sensitivity, and the like upon repeated use. May occur. Additives for these include 1-chloroanthraquinone, benzoquinone,
2,3-dichloronaphthoquinone, naphthoquinone, 4,
4′-dinitrobenzophenone, 4,4′-dichlorobenzophenone, 4-nitrobenzophenone, 4-nitrobenzalmalonedinitrile, ethyl α-cyano-β- (p-cyanophenyl) acrylate, 9-anthracenylmethyl Electron withdrawing compounds such as malondinitrile, 1-cyano-1- (p-nitrophenyl) -2- (p-chlorophenyl) ethylene and 2,7-dinitrofluorenone. In addition, as additives to the photoreceptor, an antioxidant, an anti-curl agent, a leveling agent, and the like can be added as necessary.

The benzofuran-styryl compound according to the present invention is dissolved or dispersed in an appropriate solvent together with the various additives described above depending on the form of the photoreceptor to prepare a coating solution. Is applied onto the conductive support 1 and dried to produce a photoreceptor. As a solvent for the coating solution, aromatic hydrocarbons such as benzene, toluene, xylene and monochlorobenzene, halogenated hydrocarbons such as dichloromethane and dichloroethane,
A single solvent such as tetrahydrofuran, dioxane, dimethoxymethyl ether, and dimethylformamide or a mixture of two or more solvents can be used. These solvents can be used by further adding a solvent such as alcohols, acetonitrile and methyl ethyl ketone, if necessary.

The intermediate layer 8 provided between the conductive support 1 and the photosensitive layer 4 or 14 imparts a protective function or an adhesive function, enhances coating properties, and further injects electric charge from the substrate to the photosensitive layer. For the purpose of improvement, as such a material, casein, polyvinyl butyral, polyvinyl alcohol, nitrocellulose, ethylene-acrylic acid copolymer, polyamide, polyurethane, gelatin, aluminum oxide and the like are suitable. Examples of the polyamide include nylon 6, nylon 66, nylon 610, copolymer nylon, and alkoxymethylated nylon.

Hereinafter, the production examples of the benzofuran-styryl compound according to the present invention and the electrophotographic photoreceptor according to the present invention will be specifically described based on examples. The present invention is not limited thereby.

(Production Example) A benzofuran-styryl compound (Exemplary Compound No. 1) was produced.

0.81 g of potassium tert-butoxide
(1.5 equivalents) dissolved in 5 ml of tetrahydrofuran,
Cooled to 0 ° C. in a water bath. To this solution, a solution in which 1.9 g (1.3 equivalents) of diethyl α, α′-diphenylbenzylphosphonate was dissolved in 5 ml of tetrahydrofuran was gradually added. Stir at 0 ° C. for about 10 minutes to produce a stable Wittig ylide. To this solution was added 5-formyl-2-
A solution of 2.0 g (1.0 equivalent) of (4 ′ (bis (p-tolyl) amino) phenyl) benzo [b] furan in 10 ml of tetrahydrofuran was gradually added. The water bath was removed, the reaction temperature was raised to room temperature, and stirring was continued for about 2 hours.

After the completion of the reaction was confirmed by thin-layer chromatography, the desired benzofuran-
2.58 g of a styryl compound (Exemplary Compound No. 1) was obtained. The yield was 95%.

The structure of the thus obtained benzofuran-styryl compound (Exemplary Compound No. 1) is represented by ¹ H—N
MR, usually ¹³ C-NMR and DEPT 135 ¹³ C-
Confirmed by measuring NMR.

FIG. 6 shows ¹ H—N of a benzofuran-styryl compound (exemplified compound No. 1) in deuterated chloroform.
It is an HR spectrum. FIG. 7 shows a benzofuran-styryl compound (exemplary compound No. 1) in deuterated chloroform.
Is a normal ¹³ C-NMR spectrum. FIG. 8 is a ¹³ C-NMR spectrum of a benzofuran-styryl compound (exemplary compound No. 1) in deuterated chloroform at DEPT135. These NMR signals well support the structure of the target benzofuran-styryl compound (Exemplary Compound No. 1).

(Examples 1 to 4, Comparative Example) In the charge transfer layer 6 shown in FIG.
Examples 1, 2, 3 and 4 containing the benzofuran-styryl compounds shown in 1, 5, 14 and 21, respectively, and the conventionally known 4- (diethylamino) -benzaldehyde-N, N-diphenylhydrazone. Five types of electrophotographic photosensitive members of the comparative example were manufactured.

In a 1% THF (tetrahydrofuran) solution of a phenoxy resin (PKHH: manufactured by Union Carbide), a bisazo pigment represented by the following structural formula (VII) is added in the same amount as the resin in a weight ratio, and a paint conditioner ( (Red Devil Co., Ltd.) with glass beads having a diameter of 1.5 mm for about 2 hours to prepare a coating solution for a charge generation layer. The prepared coating solution for a charge generation layer was applied by a doctor blade method onto a support of an aluminum-evaporated polyester film (80 μm in thickness) and dried to form a charge generation layer. The thickness of the charge generation layer after drying is 0.2
μm.

[0092]

Embedded image

Exemplified Compound No. 1, 4, 12 or 23
A benzofuran-styryl compound represented by
1 g of (diethylamino) -benzaldehyde-N, N-diphenylhydrazone and a polyarylate resin (U-
100: manufactured by Unitika Ltd.), and a 15% solution of 1.2 g in THF was prepared to prepare five types of coating solutions for the charge transfer layer. The coating solution for each charge transfer layer was applied onto the charge generation layer formed as described above using a squeezing doctor and dried to form a 25 μm dry film thickness of the charge transfer layer, which is a resin-bisamine compound solid solution phase. Each formed, Examples 1 to
5 and 5 types of laminated electrophotographic photosensitive members of Comparative Example 1 were produced.

The electrophotographic characteristics of the laminated electrophotographic photosensitive member prepared as described above were evaluated using an electrostatic recording paper test apparatus (SP-428, manufactured by Kawaguchi Electric Co., Ltd.). Applied voltage: -6 kV and static: No. Under the measurement conditions of 3, -70 by white light irradiation (irradiation light: 5 lux)
Exposure amount E required to attenuate from 0V to -100V
100 (lux · sec) and the initial potential V0 (−volt) were measured. Further, using the above-mentioned electrostatic recording paper test apparatus, the exposure amount E100 (lux / sec) after the same operation as 10,000 times as one cycle of charge / discharge (discharge light: irradiation of white light of 40 lux for 1 second) was used. ) And the initial potential V0
(−volt) was measured. Table 4 shows the measurement results of E100 and V0 at the first time and the 10,000th time.

[0095]

[Table 4]

From Table 4, it was found that Examples 1 to 4 using the benzofuran-styryl compound according to the present invention were excellent not only in sensitivity but also in repetition characteristics as compared with Comparative Example 1 using the conventional compound. .

(Embodiment 5) The charge transfer layer 6 shown in FIG.
In addition, as the charge transfer material 3, exemplified compound No. The laminated electrophotographic photoreceptor of Example 5 containing the benzofuran-styryl compound shown in No. 3 was produced.

0.4 g of an x-type metal-free phthalocyanine (Fastgen Blue 8120: manufactured by Dainippon Ink) represented by the following structural formula (VIII) was added to a vinyl chloride: vinyl acetate copolymer resin (Eslex M: Sekisui Chemical) 0.3)
g was dissolved in 30 ml of a dissolved ethyl acetate solution, and dispersed in a paint conditioner for about 20 minutes to prepare a coating solution for a charge generation layer. The prepared coating solution for the charge generation layer is applied by a doctor blade method on a support of an aluminum-evaporated polyester film and dried, and charge generation is performed so that the thickness of the charge generation layer after drying becomes 0.4 μm. A layer was formed.

[0099]

Embedded image

On the charge generation layer, the exemplified compound No. 2
The charge transfer layer of a polyarylate layer containing the benzofuran-styryl compound at a weight ratio of 50% was laminated to produce a multilayer electrophotographic photosensitive member of Example 5 composed of two layers.

The energy required for halving the potential (E50) and the initial potential (-V0) were obtained by using the light of 780 nm of the photoreceptor of Example 5 to find that V0 = -690 (volt).
And E50 = 0.21 (μJ), indicating that the photosensitive member had extremely high sensitivity and high chargeability.

A laser printer (WD-580P:
(Sharp Corp.) was modified, the photoreceptor of Example 5 was stuck on the drum portion, and continuous blank copy (Non Copy Aging) was performed 10,000 times, and the degree of the initial potential drop and the sensitivity drop was examined. As a result, V0 = −680 (volt) and E
At 50 = 0.22 (μJ), there was almost no change in the value compared to the first time.

(Examples 6 to 9) As the charge transfer material 3 shown in FIG. 6, 8, 13 or 24
The four types of electrophotographic photoreceptors having the single-layer photosensitive layer 14 containing the benzofuran-styryl compound shown in FIG.

1 g of Exemplified Compound No. 6, 8, 13 or 24, 1.1 g of a polycarbonate resin represented by the following structural formula (IX), N, N-3,5-xylyl-3,4,4
9,10-perylenetetracarboximide 0.15
g and the ultraviolet absorber 0.05 g in methylene chloride 1
A coating solution for a photosensitive layer dissolved in 4.0 ml was prepared. The imide compound was partially dispersed in the coating solution for the photosensitive layer. The prepared coating solution for a photosensitive layer is applied to a support having an alumite-processed aluminum substrate surface (alumite layer: 7 μm) using an applicator, and dried to obtain a single-layer photosensitive member having a dried photosensitive layer thickness of 20 μm. Was.

[0105]

Embedded image

The electrophotographic characteristics of the single-layer type electrophotographic photosensitive member produced as described above were evaluated by the above-mentioned electrostatic recording paper test apparatus. Applied voltage: 5.5 kV and static: No. Exposure amount E100 (lux · sec) required to attenuate from +700 V to +100 V by white light irradiation (irradiation light: 5 lux) under the measurement conditions of 3
Was measured. In addition, 10,000 continuous blank copies were made, and the degree of decrease in sensitivity (E100) was examined. Table 5 shows the measurement results of E100 at the first time and at the 10,000th time.

[0107]

[Table 5]

From Table 5, it was found that the photoreceptors of Examples 6 to 9 using the benzofuran-styryl compound according to the present invention had excellent sensitivity and repetition characteristics even in positive charging.

[0109]

As described above, according to the present invention, a high sensitivity and a high durability can be obtained by having a wide conjugated system, excellent compatibility with a binder polymer, and difficulty in precipitation as crystals. Can be used as a charge transfer material for an electrophotographic photoreceptor, that is, a novel benzofuran-styryl compound having a benzofuran skeleton.

Further, according to the present invention, by reacting a benzo [b] furanaldehyde compound with a phosphorus reagent, a benzofuran-styryl compound which is excellent as a charge transfer material for an electrophotographic photoreceptor can be produced very easily in high yield. A manufacturing method for manufacturing can be provided.

Therefore, according to the present invention, by containing the benzofuran-styryl compound as a charge transfer material, it has high sensitivity and high durability in an organic system, and is nontoxic and resource-friendly compared to an inorganic system. Electrophotographic photoreceptor with excellent characteristics that is transparent, lightweight, excellent in film-forming properties, has both positive and negative charging properties, is easy to manufacture, and hardly reduces photosensitivity even when used repeatedly. Can be provided.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view schematically showing an example of an electrophotographic photosensitive member having a function-separated type photosensitive layer having a charge transfer layer 6 on a charge generation layer 5.

FIG. 2 is a function-separated type photosensitive layer having a charge generation layer 5 on a charge transfer layer 6;

FIG. 3 is a cross-sectional view schematically illustrating an example of an electrophotographic photosensitive member having a dispersion-type photosensitive layer.

FIG. 4 is a cross-sectional view showing an example having a surface protective layer 7 in the electrophotographic photoreceptor of FIG.

FIG. 5 is a cross-sectional view showing an example having an intermediate layer 8 in the electrophotographic photoreceptor of FIG.

FIG. 6 is a ¹ H-NHR spectrum of a benzofuran-styryl compound (exemplary compound No. 1) in deuterated chloroform.

FIG. 7 is a normal ¹³ C-NMR spectrum of a benzofuran-styryl compound (exemplified compound No. 1) in deuterated chloroform.

FIG. 8 shows the benzofuran-styryl compound (exemplary compound No. 1) ^{13 in} DEPT135 in deuterated chloroform.
It is a C-NMR spectrum.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Conductive support 2 Charge generation material 3 Charge transfer material 4, 14 Photosensitive layer 5 Charge generation layer 6 Charge transfer 7 Surface protective layer 8 Intermediate layer

Claims (8)

[Claims] 1. An electrophotographic photoreceptor characterized in that a photosensitive layer provided on a conductive support contains a benzofuran-styryl compound represented by the following general formula (I) as a charge transfer material. . Embedded image (Wherein, Ar ₁ represents an arylene group which may have a substituent or a divalent heterocyclic group which may have a substituent. Ar ₂
Represents an aryl group which may have a substituent, a heterocyclic group which may have a substituent, or an aralkyl group which may have a substituent. Ar ₃ and Ar ₄ are an aryl group which may have a substituent, a heterocyclic group which may have a substituent, an aralkyl group which may have a substituent, and an alkyl having 1 to 3 carbon atoms which may have a substituent. Represents a group or a hydrogen atom. a
Is an alkyl group having 1 to 5 carbon atoms which may have a substituent, a fluoroalkyl group having 1 to 5 carbon atoms which may have a substituent, a perfluoroalkyl group having 1 to 5 carbon atoms which may have a substituent, Alkoxy group of number 1 to 3, carbon number 1
3 represents a dialkylamino group, a halogen atom or a hydrogen atom, and n represents an integer of 1 to 4. However, when n is 2 or more, a plurality of a may be the same or different, and may form a ring with each other. ) 2. The method according to claim 1, wherein the benzofuran-styryl compound is
2. The electrophotographic photosensitive member according to claim 1, which is a compound represented by the following general formula (II). Embedded image (In the formula, b is an alkyl group having 1 to 5 carbon atoms which may have a substituent, a fluoroalkyl group having 1 to 5 carbon atoms which may have a substituent, and a par having 1 to 5 carbon atoms which may have a substituent. A fluoroalkyl group, an alkoxy group having 1 to 3 carbon atoms, a dialkylamino group having 1 to 3 carbon atoms, a halogen atom or a hydrogen atom, and m represents an integer of 1 to 4. However, when m is 2 or more, B may be the same or different.
r ₂ , Ar ₃ , Ar ₄ , a and n have the same meanings as those shown in formula (I). ) 3. The benzofuran-styryl compound,
The electrophotographic photoreceptor according to claim 1, which is a compound represented by the following general formula (III). Embedded image (In the formula, d is an alkyl group having 1 to 5 carbon atoms which may have a substituent, a fluoroalkyl group having 1 to 5 carbon atoms which may have a substituent, and 1 to 5 carbon atoms which may have a substituent. Represents a fluoroalkyl group, an alkoxy group having 1 to 3 carbon atoms, a dialkylamino group having 1 to 3 carbon atoms, a halogen atom or a hydrogen atom, and l represents an integer of 1 to 5. However, when l is 2 or more, May be the same or different.
r ₃ , Ar ₄ , a, b, n and m have the same meanings as those shown in formula (II). ) 4. The benzofuran-styryl compound,
The electrophotographic photoreceptor according to claim 1, which is a compound represented by the following general formula (IV). Embedded image (Wherein, e is an alkyl group having 1 to 5 carbon atoms which may have a substituent, a fluoroalkyl group having 1 to 5 carbon atoms which may have a substituent, and a peralkyl group having 1 to 5 carbon atoms which may have a substituent. A fluoroalkyl group, an alkoxy group having 1 to 3 carbon atoms, a dialkylamino group having 1 to 3 carbon atoms, a halogen atom or a hydrogen atom, and k represents an integer of 1 to 5. However, when k is 2 or more, May be the same or different.
r ₃ , Ar ₄ , a, b, n and m are represented by the general formula (III)
Is the same as that shown in. ) 5. The photosensitive layer according to claim 1, wherein the photosensitive layer has a laminated structure of a charge generation layer containing a charge generation material and a charge transfer layer containing the charge transfer material. The electrophotographic photoreceptor according to any one of the above. 6. The electrophotographic photoreceptor according to claim 1, wherein the photosensitive layer comprises a single layer containing a charge generating substance and the charge transfer substance. 7. A benzofuran-styryl compound represented by the following general formula (I). Embedded image (Wherein, Ar ₁ represents an arylene group which may have a substituent or a divalent heterocyclic group which may have a substituent. Ar ₂
Represents an aryl group which may have a substituent, a heterocyclic group which may have a substituent, or an aralkyl group which may have a substituent. Ar ₃ and Ar ₄ are an aryl group which may have a substituent, a heterocyclic group which may have a substituent, an aralkyl group which may have a substituent, and an alkyl having 1 to 3 carbon atoms which may have a substituent. Represents a group or a hydrogen atom. a
Is an alkyl group having 1 to 5 carbon atoms which may have a substituent, a fluoroalkyl group having 1 to 5 carbon atoms which may have a substituent, a perfluoroalkyl group having 1 to 5 carbon atoms which may have a substituent, Alkoxy group of number 1 to 3, carbon number 1
3 represents a dialkylamino group, a halogen atom or a hydrogen atom, and n represents an integer of 1 to 4. However, when n is 2 or more, a plurality of a may be the same or different, and may form a ring with each other. ) 8. A benzo [b] furanaldehyde compound represented by the following general formula (V), and a compound represented by the following general formula (VI)
A method for producing a benzofuran-styryl compound represented by the following general formula (I) by reacting a benzofuran-styryl compound represented by the following general formula (I). Embedded image (Wherein, Ar ₁ represents an arylene group which may have a substituent or a divalent heterocyclic group which may have a substituent. Ar ₂
Represents an aryl group which may have a substituent, a heterocyclic group which may have a substituent, or an aralkyl group which may have a substituent. Ar ₃ and Ar ₄ are an aryl group which may have a substituent, a heterocyclic group which may have a substituent, an aralkyl group which may have a substituent, and an alkyl having 1 to 3 carbon atoms which may have a substituent. Represents a group or a hydrogen atom. a
Is an alkyl group having 1 to 5 carbon atoms which may have a substituent, a fluoroalkyl group having 1 to 5 carbon atoms which may have a substituent, a perfluoroalkyl group having 1 to 5 carbon atoms which may have a substituent, Alkoxy group of number 1 to 3, carbon number 1
3 represents a dialkylamino group, a halogen atom or a hydrogen atom, and n represents an integer of 1 to 4. However, when n is 2 or more, a plurality of a may be the same or different, and may form a ring with each other. ) (In the formula (V), Ar ₁ , Ar ₂ , a and n have the same meanings as those shown in the general formula (I). (In the formula (VI), Ar ₃ and Ar ₄ have the same meanings as those shown in the general formula (I). Ar ₅ is an aryl group optionally having a substituent, an aralkyl group optionally having a substituent or It shows a C1-C3 alkyl group which may contain a substituent.