JPH08151372A - Bisoxadiazole derivative and photographic photoreceptor using the same - Google Patents

Abstract

PURPOSE: To obtain a new compound having good solubility to solvents and compatibility with binder resins, excellent in matching with electron charge- generating agents, thereby excellent in electron-transporting property in low electric field and capable of providing an electrophotographic photoreceptor having high sensitivity as an electron transporting agent. CONSTITUTION: This compound is expressed by a compound of formula I (R<1> is an alkyl, an alkoxy, etc.; R<2> is an alkyl or nitro; (m) is 0-3; (n) is 0-2), e.g. a compound of formula II. The compound is obtained by reacting, e.g. a compound of formula III such as 2-methyl-5-nitrobenzhydrazide with a compound of formula IV such as 5-t-butylisophthalic acid chloride in a solvent such as dehydrated pyridine under inert gas atmosphere at 25-120 deg.C for 30min to 24hr to carry out cyclization reaction by intramolecular condensation. Furthermore, the compound of formula III is preferably obtained by reacting an ester of benzoic acid with hydrazine.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bisoxadiazole derivative and an electrophotographic photoreceptor using the same, and more specifically, to an electron transport in an electrophotographic organic photoreceptor used in a copying machine, a laser printer or the like. The present invention relates to a bisoxadiazole derivative preferably used as an agent.

[0002]

2. Description of the Related Art Electrophotographic photoreceptors made of various materials are used in image forming apparatuses such as copying machines using the Carlson process. One is an inorganic photoreceptor using an inorganic material such as selenium in the photosensitive layer, and the other is an organic photoreceptor using an organic material in the photosensitive layer. Extensive research has been conducted because organic photoreceptors have many advantages such as being inexpensive and having high productivity as compared with inorganic photoreceptors and being non-polluting.

As the organic photoconductor, there are many so-called function-separated type organic photoconductors in which a charge generation layer and a charge transport layer are laminated, that is, laminated photoconductors, but a charge generation agent and a charge transport agent are used as the photoconductive layer. A single-layer type organic photoconductor dispersed therein is also known. Charge transport agents used in these photoreceptors are required to have high carrier mobility, but most charge transport agents having high carrier mobility have hole transporting properties. Therefore, it is practically limited to the negative charging type laminated organic photoreceptor having the charge transport layer as the outermost layer from the viewpoint of mechanical strength. However, since the negative charge type organic photoconductor uses negative corona discharge, a large amount of ozone is generated, and thus there are problems such as pollution of the environment and deterioration of the photoconductor.

Therefore, in order to eliminate such drawbacks, the use of an electron transfer agent as a charge transfer agent has been studied, and in JP-A-1-206349, a compound having a diphenoquinone structure is electrophotographic. It has been proposed to use it as an electron transfer material for photoreceptors. However, in general, conventional electron transfer agents containing diphenoquinones have poor compatibility with the binder resin and have a long hopping distance, so that electron transfer in a low electric field does not easily occur. Therefore, the electrophotographic photoreceptor containing the conventional electron transfer material has a drawback that the residual potential is considerably high and the sensitivity is low.

The main object of the present invention is to provide a novel bisoxadiazole derivative having an excellent electron transporting ability. Another object of the present invention is to provide a single-layer type and a multi-layer type electrophotographic photoconductor in which the residual potential is suppressed to a low level and which exhibits excellent sensitivity.

[0006]

[Means and Actions for Solving the Problems] As a result of intensive studies to achieve the above objects, the present inventors have found that the general formula (1):

[0007]

[Chemical 4]

(In the formula, R ¹ represents an alkyl group, an alkoxyl group or a halogen atom, R ² represents an alkyl group or a nitro group, m is an integer of 0 to 3, and n is an integer of 0 to 2. It was found that the bisoxadiazole derivative represented by the formula (4) has a higher electron-transporting ability than the conventional diphenoquinone-based compound, and the present invention has been completed.

The bisoxadiazole derivative represented by the general formula (1) has good solubility in a solvent and compatibility with a binder resin, and is excellent in matching with a charge generating agent. The electron injection is smoothly performed, and the electron transport property is excellent especially in a low electric field. Therefore, when the compound of the general formula (1) in the present invention is used as an electron transfer agent in an electrophotographic photoreceptor, a highly sensitive organic photoreceptor can be provided.

Further, the compound (1) of the present invention can be used for applications such as solar cells and EL devices by utilizing its high electron transporting ability. Each group represented by the general formula (1) will be specifically described. As an alkyl group,
For example, methyl, ethyl, n-propyl, isopropyl,
Examples thereof include groups having 1 to 6 carbon atoms such as t-butyl, pentyl and hexyl.

Examples of the alkoxyl group include groups having 1 to 6 carbon atoms such as methoxy, ethoxy, propoxy, t-butoxy, pentyloxy and hexyloxy. Examples of the halogen atom include chlorine, bromine, fluorine and iodine. The bisoxadiazole derivative (1) of the present invention includes the derivatives represented by the general formulas (3) and (4).

[0012]

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[0013]

[Chemical 6]

(In the formula, R ¹ , R ² , m and n are the same as above.) The compound represented by the general formula (1) is, for example, as shown in the following formula, a benzhydrazide derivative (5) and benzene. The compound (7) is synthesized by reacting the dicarboxylic acid derivative (6) with the compound (7), and the compound (7) is subjected to a ring closure reaction by intramolecular condensation.

Reaction process formula (I)

[0016]

[Chemical 7]

(In the formula, R ¹ , R ² , m and n are the same as above, and X represents a halogen atom.) In the above formula (I), the compound (5) is different from the compound (6). It is used in a proportion of at least twice the molar amount. Also, the compound (5)
Examples of the solvent used in the reaction for synthesizing compound (7) from compound (6) and compound (6) include dehydrated pyridine. The reaction is usually carried out at a temperature of 25 to 120 ° C. for 30 minutes to 2 under an atmosphere of an inert gas such as argon or nitrogen.
It will be held for about 4 hours.

The solvent used in the reaction for synthesizing compound (1) from compound (7) includes, for example, phosphoryl chloride (POCl ₃ ). The reaction is usually carried out under an atmosphere of an inert gas such as argon or nitrogen such as 25 to
It is performed at a temperature of 130 ° C. for about 30 minutes to 24 hours.
The benzhydrazide derivative (5) can be obtained by reacting a benzoic acid derivative ester (8) with hydrazine as shown in the following reaction formula.

[0019]

Embedded image

(In the formula, R ¹ , m and n are the same as above. R ³ represents an alkyl group.) Specific examples of the compound represented by the general formula (3) are shown by the following formula (3-1). ~
It is shown in (3-3).

[0021]

[Chemical 9]

Specific examples of the compound represented by the general formula (4) are shown in the following formulas (4-1) to (4-3).

[0023]

[Chemical 10]

Further, the compound of the present invention in which the substituent R ² is an alkyl group has particularly high solubility in a solvent and compatibility with the binder resin, and the compound of the present invention in which R ² is a nitro group is In particular, the sensitivity of the photoconductor can be improved. The electrophotographic photoreceptor of the present invention is one in which an organic photosensitive layer is provided on a conductive substrate, and the binder resin in this organic photosensitive layer is a bisoxadiazole derivative represented by the general formula (1). Is contained as an electron transfer agent.

The electrophotographic photosensitive member of the present invention is roughly classified into a single layer type and a laminated type. The single-layer type electrophotographic photoconductor is one in which an organic photosensitive layer is provided on a conductive substrate, and the organic photosensitive layer is a binder resin containing at least a charge generating agent and a hole transporting agent, and The bisoxadiazole derivative represented by the formula (1) is contained as an electron transfer agent. In this single-layer type electrophotographic photosensitive member, the residual potential of the photosensitive member is greatly reduced, and the sensitivity can be improved. The single-layer type photoreceptor of the present invention can be applied to both positive charging and negative charging, but it is particularly preferable to use the positive charging type.

When the organic photosensitive layer of the single-layer type electrophotographic photosensitive member contains an electron-accepting compound having an oxidation-reduction potential of -0.8 to -1.3 V, the electron withdrawing from the charge generating agent is removed. It can be performed efficiently, and the sensitivity of the photoconductor is further improved. On the other hand, the multilayer electrophotographic photoreceptor of the present invention is one in which at least a charge generation layer and a charge transport layer are provided in this order on a conductive substrate, and the charge transport layer has the above general formula (1) as an electron transport agent. ) The bisoxadiazole derivative represented by

This electrophotographic photosensitive member is used as a positive charging type, and the residual potential is greatly reduced, and the sensitivity can be improved. In order to smoothly transfer electrons from the charge generation layer to the charge transport layer, the charge generation layer also has the general formula (1)
It is preferable to include a bisoxadiazole derivative represented by

Further, in a laminated electrophotographic photosensitive member in which at least a charge generation layer and a charge transport layer are provided in this order on a conductive substrate, the charge transport layer is represented by the general formula (1) as an electron transport agent. An electron-accepting compound having a redox potential of −0.8 to −1.3 V may be contained in the charge generation layer, while containing the bisoxadiazole derivative.

The oxidation-reduction potential is measured by the following materials using a three-electrode type cyclic voltammetry. Electrode: working electrode (glassy carbon electrode), counter electrode (platinum electrode) Reference electrode: silver nitrate electrode (0.1 mol / liter AgNO)
₃ - acetonitrile) Measurement solution electrolyte: perchlorate tetra -n- butylammonium 0.1 mol analyte: electron transporting agent 0.001 mol solvent: formulated with CH ₂ Cl ₂ 1 liter or more materials measurement solution Prepare.

Calculation of redox potential: As shown in FIG.
The relationship between the index voltage (V) and the current (μA) is obtained, E ₁ and E ₂ shown in the figure are measured, and the redox potential is obtained by the following calculation formula. Redox potential = (E ₁ + E ₂ ) / 2 (V) The compound represented by the general formula (1) in the present invention has good solubility in a solvent and compatibility with a binder resin, and Excellent matching with the charge generating agent, smooth injection of electrons, and excellent electron transporting property especially in a low electric field.

Therefore, the single-layer type positive charging photoreceptor of the present invention is
The electrons released from the charge generating agent in the exposure step are smoothly injected into the electron transfer agent represented by the general formula (1), and then the electrons are transferred to and from the photosensitive layer by the transfer of electrons between the electron transfer agents. Then, the positive charge (+) charged on the surface of the photosensitive layer is canceled. On the other hand, holes (+) are injected into the hole transport material, move to the surface of the conductive substrate without being trapped in the middle, and cancel the negative charge (-) on the surface of the conductive substrate. In this way, the sensitivity of the positive charging type photoconductor is considered to be improved. When the single-layer type photoreceptor is used with negative charging, the sensitivity is similarly improved only by reversing the direction of charge transfer.

Further, in the laminated positive charging photoreceptor of the present invention,
Electrons released from the charge generating agent in the charge generating layer in the exposure step are smoothly injected into the electron transferring agent represented by the general formula (1) in the charge transferring layer, and then the electrons between the electron transferring agents are changed. Upon transfer, the electrons move in the charge transport layer, reach the surface of the photosensitive layer, and cancel the positive charge (+) charged in advance on the surface of the photosensitive layer. On the other hand, holes (+) move directly from the charge generation layer to the surface of the conductive substrate, and cancel the negative charge (-) on the surface of the conductive substrate. It is considered that the sensitivity of the layered positively charged photoreceptor is improved in this way.

The charge generating agent, which absorbs light upon exposure to the photoreceptor, produces ion pairs [holes (+) and electrons (-)]. In order for the generated ion pairs to become free carriers and effectively cancel the surface charge, it is preferable that the ion pair recombine and disappear. When an electron-accepting compound having an oxidation-reduction potential of −0.8 to −1.3 V is present, LUMO (means the highest energy level in the molecular orbitals occupied by electrons in the molecule). , The excited electron is usually an electron of this level.) Since the energy level of the electron is lower than that of the charge generating agent, the electron moves to the electron-accepting compound during the generation of the ion pair, and the ion pair becomes the carrier. It becomes easy to separate into. That is, the electron-accepting compound acts on the charge generation to improve the generation efficiency.

On the other hand, in order to have high sensitivity, it is necessary that carrier traps due to impurities do not occur when the free carriers move. Usually, a trap due to a small amount of impurities exists in the moving process of the free carrier, and the free carrier moves while repeating trap-detrap. Therefore, when the free carriers fall to a level where they cannot be untrapped, they become carrier traps and their movement is stopped.

When an electron-accepting compound having an oxidation-reduction potential of higher than -0.8 V is used, the separated free carriers are dropped to a level that cannot be detrapped and carrier traps occur. On the contrary, the redox potential is −
LUM for electron-accepting compounds less than 1.3 V
The energy level of O becomes higher than that of the charge generating agent, and when the ion pair is generated, the electrons do not move to the electron accepting compound,
It is considered that this does not lead to improvement in charge generation efficiency.

As the hole-transporting agent, conventionally known hole-transporting substances are used, for example, oxadiazole such as 2,5-di (4-methylaminophenyl) and 1,3,4-oxadiazole. Compounds, styryl compounds such as 9- (4-diethylaminostyryl) anthracene, carbazole compounds such as polyvinylcarbazole, organic polysilane compounds, pyrazoline compounds such as 1-phenyl-3- (p-dimethylaminophenyl) pyrazoline, Nitrogen-containing cyclic compounds such as hydrazone compounds, triphenylamine compounds, indole compounds, oxazole compounds, isoxazole compounds, thiazole compounds, thiadiazole compounds, imidazole compounds, pyrazole compounds, and triazole compounds, Such as condensed polycyclic compounds .

These charge transport materials may be used alone or in admixture of two or more. Further, when using a charge transport material having film-forming properties such as polyvinylcarbazole, the binder resin is not always necessary. In the present invention, among the hole transport materials, the ionization potential (Ip) is 4.8 to.
It is preferable to use the one of 5.6 eV and the electric field strength of 3
Those having a mobility of 1 × 10 ⁻⁶ cm ² / V · sec or more at × 10 ⁵ V / cm are particularly preferable. Specifically, alkyl-substituted triphenylamine derivatives are preferable.

The ionization potential of the hole-transporting material is measured by using an atmospheric photoelectron analyzer (AC-1 manufactured by Riken Keiki Co., Ltd.) as in the electron-transporting material. In the present invention, by using a hole transfer agent having an ionization potential within the above range, the residual potential can be further lowered and the sensitivity can be improved. The reason is not clear, but it is considered as follows.

That is, the easiness of injecting charges from the charge generating agent into the hole transferring material is closely related to the ionization potential of the hole transferring material, and the ionization potential of the hole transferring material is higher than the above range. If it is large, the degree of charge injection from the charge generating agent to the hole transporting agent will be low, or the degree of transfer of holes between the hole transporting agents will be low, resulting in a decrease in sensitivity. Is recognized.

On the other hand, in a system in which a hole transfer material and an electron transfer material coexist, it is necessary to pay attention to the interaction between them and more specifically to the formation of a charge transfer complex. When such a complex is formed between the two, recombination occurs between the holes and the electrons, and the mobility of the charge is lowered as a whole. When the ionization potential of the hole transfer material is smaller than the above range, the tendency to form a complex with the electron transfer material increases, and electron-hole recombination occurs, resulting in an apparent quantum yield. Is likely to decrease, resulting in a decrease in sensitivity.

Therefore, a bulky substituent is introduced into the bisoxadiazole derivative represented by the general formula (1), and the steric hindrance thereof suppresses the formation of a complex with the hole transfer agent. Preferably. The hole transporting agent used in the present invention is not particularly limited, but for example, 1,1-bis (4-diethylaminophenyl) -4,4-diphenyl-1,3-butadiene, N,
N'-bis (2,4-dimethylphenyl) -N, N'-
Diphenylbenzidine, 3,3'-dimethyl-N, N,
N ', N'-tetrakis-4-methylphenyl (1,
1'-biphenyl) -4,4'-diamine, N-ethyl-3-carbazolylaldehyde-N, N'-diphenylhydrazone, 4- [N, N-bis (p-toluyl) amino] -β- Examples include phenyl stilbene.

The electron-accepting compound is not particularly limited as long as it has an electron-accepting property and an oxidation-reduction potential of -0.8 to -1.3 V, and examples thereof include benzoquinone compounds and naphthoquinone compounds. Anthraquinone type, diphenoquinone type, malononitrile, thiopyran type compound, 2,
4,8-trinitrothioxanthone, 3,4,5,7-
Examples thereof include fluorenone compounds such as tetranitro-9-fluorenone, dinitroanthracene, dinitroacridine, nitroanthraquinone and dinitroanthraquinone. Of these, the diphenoquinone type has a quinone type oxygen atom excellent in electron-accepting property bonded to the end of the molecular chain, and since there is a conjugated double bond over the entire long molecular chain, the transfer of electrons within the molecule also occurs. It is particularly preferable because it has the advantage that it is easy and the transfer of electrons is easy. Further, each electron-accepting compound described above contributes to the generation of charges.

Examples of the benzoquinone compound include p-benzoquinone, 2,6-dimethyl-p-benzoquinone and 2,6-di-t-butyl-p-benzoquinone. Further, as the diphenoquinone compound,
Examples include derivatives represented by the following general formulas (9) to (12).

[0044]

[Chemical 11]

[0045]

[Chemical 12]

(In each formula, R ⁴ , R ⁵ , R ⁶ , R ⁷ , R ⁸
And R ⁹ are the same or different and each represents a hydrogen atom, an alkyl group, an alkoxy group, an aryl group, an aralkyl group, a cycloalkyl group, or an amino group which may have a substituent. ) Examples of the alkyl group include alkyl groups having 1 to 6 carbon atoms such as methyl, ethyl, n-propyl, isopropyl, t-butyl, pentyl and hexyl groups, and examples of the alkoxy group include methoxy, ethoxy and propoxy groups. ,
An alkoxy group having 1 to 6 carbon atoms such as t-butoxy, pentyloxy and hexyloxy groups, an aryl group such as a phenyl group and a naphthyl group, and an aralkyl group such as benzyl, benzhydryl, trityl and phenethyl. Groups, etc., as the cycloalkyl group,
Examples thereof include cycloalkyl groups having 3 to 6 carbon atoms such as cyclopropyl, cyclobutyl, cyclopentyl and cyclohexyl. The amino group which may have a substituent includes, for example, an amino group, monomethylamino, dimethylamino, monoethylamino,
Examples thereof include a diethylamino group.

Specific examples of the diphenoquinone compounds represented by the formulas (9) to (12) include, for example, 3,5-dimethyl-
3 ', 5'-dit-butyldi-4,4'-diphenoquinone, 3,3'-dimethyl-5,5'-dit-butyl-
4,4'-diphenoquinone, 3,5'-dimethyl-3,
Examples thereof include 5'-di-t-butyl-4,4'-diphenoquinone. The diphenoquinone-based compound having these substituents is preferable because the symmetry of the molecule is low, the interaction between the molecules is small, and the solubility is excellent. Also,
Examples of the diphenoquinone compound represented by the formula (9) include 3,3 ', 5,5'-tetramethyl-4,4'-diphenoquinone and 3,3', 5,5'-tetraethyl-
4,4'-diphenoquinone, 3,3 ', 5,5'-tetra-t-butyl-4,4'-diphenoquinone and the like can be mentioned. These diphenoquinone compounds can be used alone or in combination of two or more.

As the charge generating agent used in the present invention, for example, selenium, selenium-tellurium, amorphous silicon, pyrylium salt, azo pigment, ansanthuron pigment, phthalocyanine pigment, perylene pigment, naphthalocyanine pigment, Examples thereof include indigo pigments, triphenylmethane pigments, slene pigments, toluidine pigments, pyrazoline pigments, quinacridone pigments and dithioketopyrrolopyrrole pigments. These charge generating agents may be used alone or in combination of two or more so as to have an absorption wavelength in a desired region. At that time, in connection with the use of a hole transfer agent having an ionization potential of 4.8 to 5.6 eV, a charge generation agent having an ionization potential balanced with the hole transfer agent, specifically, Has an ionization potential of 4.8 to 6.0 eV, particularly 5.0 to 5.
Use of the one in the range of 8 eV reduces the residual potential,
Desirable for improving sensitivity. Examples of particularly suitable charge generating agents include phthalocyanine-based pigments such as X-type metal-free phthalocyanine and oxotitanyl phthalocyanine, or perylene-based pigments.

Of these, the phthalocyanine pigment is 70
It is suitable as a charge generating material for a photoconductor having sensitivity in a wavelength region of 0 nm or more. That is, since the phthalocyanine-based pigment is excellent in matching with the compound (electron transfer agent) represented by the general formula (1), the electrophotographic photoreceptor using both of them has high sensitivity in the above wavelength range. Therefore, it can be suitably used for an image forming apparatus of a digital optical system using a light source having a wavelength of 700 nm or more.

Further, as the perylene pigment, a general formula is used.
(2):

[0051]

[Chemical 13]

A compound represented by the formula (in the formula, R ^a , R ^b , R ^c and R ^d are the same or different and each represents a hydrogen atom, an alkyl group, an alkoxyl group or an aryl group) is preferably used. . Examples of the alkyl group, alkoxy group and aryl group in the general formula (2) include the same groups as described above. This perylene-based pigment is suitable as a charge generating material for a photoreceptor having sensitivity in the visible region. That is,
The perylene-based pigment (2) is excellent in matching with the compound (electron transfer agent) represented by the general formula (1), and therefore the electrophotographic photoreceptor using both of them has high sensitivity in the visible region, Therefore, it can be suitably used for an image forming apparatus of an analog optical system using a light source having a wavelength in the visible region.

As the binder resin for dispersing each of the above components, various resins conventionally used in organic photosensitive layers can be used. For example, a styrene polymer,
Styrene-butadiene copolymer, styrene-acrylonitrile copolymer, styrene-maleic acid copolymer, acrylic copolymer, styrene-acrylic acid copolymer, polyethylene, ethylene-vinyl acetate copolymer, chlorinated polyethylene, poly Vinyl chloride, polypropylene, ionomer, vinyl chloride-vinyl acetate copolymer, polyester,
Alkyd resin, polyamide, polyurethane, polycarbonate, polyarylate, polysulfone, diallyl phthalate resin, ketone resin, polyvinyl butyral resin,
Thermoplastic resin such as polyether resin, polyester resin, silicone resin, epoxy resin, phenol resin,
Examples thereof include urea resins, melamine resins, other crosslinkable thermosetting resins, and photocurable resins such as epoxy acrylate and urethane-acrylate. These binder resins can be used alone or in combination of two or more. Suitable resins are styrene polymers, acrylic polymers, styrene-acrylic copolymers, polyesters, alkyd resins, polycarbonates, polyarylates and the like.

In order to obtain a single-layer type electrophotographic photosensitive member, a predetermined electron-transporting agent is dissolved or dispersed in a suitable solvent together with a charge-generating agent, a hole-transporting agent, a binder resin and the like to apply a coating solution. It may be applied on the conductive substrate by means such as the above and dried. In order to obtain a laminated type electrophotographic photoreceptor, first, a charge generation layer containing a charge generation agent is formed on a conductive substrate by means such as vapor deposition or coating, and then an electron transfer agent is formed on this charge generation layer. A coating liquid containing a binder resin and a binder resin may be applied by means such as coating and dried to form the charge transport layer.

In the single-layer type photoreceptor, the binder resin 10
The charge generating agent is added in an amount of 0.1 to 50 parts by weight, preferably 0.5 to 30 parts by weight, and the electron transporting agent is 5 to 100 parts by weight, preferably 10 to 80 parts by weight, based on 0 parts by weight. It is mixed in the ratio of. Further, the hole transfer agent is added in an amount of 5 to 500 parts by weight, preferably 25 to 200 parts by weight. Further, it is suitable that the total amount of the hole transfer agent and the electron transfer agent is 20 to 500 parts by weight, preferably 30 to 200 parts by weight, based on 100 parts by weight of the binder resin. When the single-layer type photosensitive layer contains an electron-accepting compound, the electron-accepting compound is added in an amount of 0.1 to 100 parts by weight of the binder resin.
It is suitable to add 40 parts by weight, preferably 0.5 to 20 parts by weight.

The thickness of the single layer type photosensitive layer is 5 to 100.
μm, preferably 10 to 50 μm. In the multi-layer type photoreceptor, the charge generating agent and the binder resin constituting the charge generating layer can be used in various ratios, but the charge generating agent is added in an amount of 5 to 1000 with respect to 100 parts by weight of the binder resin. It is suitable to blend in a weight ratio of 30 to 500 parts by weight. When the charge-generating layer contains an electron-accepting compound, the electron-accepting compound is contained in an amount of 0.1 to 40 parts by weight, preferably 0.5 to 20 parts by weight, based on 100 parts by weight of the binder resin.
It is suitable to blend in parts by weight. When the charge generation layer contains the bisoxadiazole derivative (1),
0.5% of this derivative (1) is added to 100 parts by weight of the binder resin.
It is suitable to blend in an amount of -50 parts by weight, preferably 1-40 parts by weight.

The electron-transporting agent and the binder resin constituting the charge-transporting layer can be used in various proportions within the range that does not hinder the transport of charge and the range that does not crystallize, but in the charge-generating layer by light irradiation. In order to easily transport the generated charge, 10 to 10 parts by weight of the electron transfer agent may be added to 100 parts by weight of the binder resin.
It is suitable to mix it in an amount of 500 parts by weight, preferably 25 to 100 resin. When the charge transport layer contains an electron-accepting compound, the electron-accepting compound is added to the binder resin 10
0.1 to 40 parts by weight, preferably 0.
It is suitable to add 5 to 20 parts by weight.

The thickness of the laminated type photosensitive layer is about 0.01 to 5 μm, preferably 0.1 to 3 μm for the charge generation layer.
The charge transport layer has a thickness of 2 to 100 μm, preferably 5 to 50 μm. In the case of a single-layer type photoreceptor, between the conductive base and the photosensitive layer, and in the case of the multilayer type photoreceptor, between the conductive base and the charge generation layer, the conductive base and the charge transport layer. Between or between the charge generation layer and the charge transport layer,
A barrier layer may be formed in a range that does not impair the characteristics of the photoreceptor. Further, a protective layer may be formed on the surface of the photoconductor.

Various additives known per se, such as an antioxidant, a radical scavenger, and a singlet quencher, are added to each of the single-layer type and laminated type photosensitive layers as long as the electrophotographic characteristics are not adversely affected. A deterioration inhibitor such as an ultraviolet absorber, a softening agent, a plasticizer, a surface modifier, a bulking agent, a thickener, a dispersion stabilizer, a wax, an acceptor, a donor and the like can be added.

In order to improve the sensitivity of the photosensitive layer,
For example, known sensitizers such as terphenyl, halonaphthoquinones and acenaphthylene may be used in combination with the charge generating agent.
In addition to the compound represented by the general formula (1), other conventionally known electron transfer agents may be contained in the photosensitive layer. Examples of such electron transfer agents include benzoquinone-based, diphenoquinone-based, malononitrile, thiopyran-based compounds, tetracyanoethylene, 2,4,8-trinitrothioxanthone, 3,4,5,7-tetranitro-9-fluorenone and the like. Fluorenone compounds, dinitrobenzene, dinitroanthracene, dinitroacridine, nitroanthraquinone, dinitroanthraquinone, succinic anhydride, maleic anhydride, dibromomaleic anhydride and the like.

As the conductive substrate used in the photoreceptor of the present invention, various conductive materials can be used. For example, aluminum, iron, copper, tin, platinum, silver, vanadium, molybdenum, chromium. , Cadmium, titanium,
Examples include simple metals such as nickel, palladium, indium, stainless steel, and brass, plastic materials in which the above metals are vapor-deposited or laminated, and glass coated with aluminum iodide, tin oxide, indium oxide, or the like.

The conductive substrate may be in the form of a sheet, a drum or the like, as long as the substrate itself has conductivity or the surface of the substrate has conductivity. Further, it is preferable that the conductive substrate has sufficient mechanical strength when used. The photosensitive layer according to the present invention is manufactured by coating a coating solution prepared by dissolving or dispersing a resin composition containing each of the above components in a solvent on a conductive substrate and drying the coating solution.

That is, the charge generating agent, charge transporting agent, binder resin and the like exemplified above are used together with an appropriate solvent by a known method such as a roll mill, a ball mill, an attritor, a paint shaker or an ultrasonic disperser. The coating liquid may be prepared by dispersing and mixing, and the coating liquid may be coated and dried by a known means. As the solvent for forming the coating liquid, various organic solvents can be used, for example, alcohols such as methanol, ethanol, isopropanol and butanol, aliphatic hydrocarbons such as n-hexane, octane and cyclohexane, benzene, Aromatic hydrocarbons such as toluene and xylene, halogenated hydrocarbons such as dichloromethane, dichloroethane, carbon tetrachloride and chlorobenzene, ethers such as dimethyl ether, diethyl ether, tetrahydrofuran, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, acetone, methyl ethyl ketone, cyclohexanone, etc. Examples thereof include ketones, esters such as ethyl acetate and methyl acetate, dimethylformaldehyde, dimethylformamide, dimethylsulfoxide and the like. These solvents can be used alone or in combination of two or more.

Further, in order to improve the dispersibility of the charge transport material or the charge generating material and the smoothness of the surface of the photosensitive layer, a surfactant, a leveling agent, etc. may be used.

[0065]

EXAMPLES The bisoxadiazole derivative of the present invention and the electrophotographic photoreceptor using the same will be described below with reference to Reference Examples, Synthesis Examples, Examples and Comparative Examples. << Synthesis of Bisoxadiazole Derivative >> Reference Example 1 25 g (0.138 mol) of 2-methyl-5-nitrobenzoic acid was added to 60 ml of dehydrated ethanol, and further concentrated sulfuric acid 4 was added.
After adding ml and refluxing for 5 hours, ethanol was distilled off. The reaction product was extracted with dimethyl ether, washed with water, and dried over anhydrous sodium sulfate. After distilling off dimethyl ether, the product was purified by silica gel column chromatography, and 2
23 g of ethyl methyl-5-nitrobenzoate (yield 80
%) Was obtained.

20 g (0.096 mol) of ethyl 2-methyl-5-nitrobenzoate was dissolved in dehydrated ethanol and refluxed under an argon atmosphere. Next, 10 ml of hydrazine monohydrate was added dropwise, and after refluxing for 14 hours, hydrazine was distilled off. After cooling the reaction product with ice, the precipitated crystals were washed with cold dimethyl ether to obtain 9.5 g (yield 51%) of 2-methyl-5-nitrobenzhydrazide. Reference Example 2 5-t-butylisophthalic acid 1 in 40 ml of thionyl chloride
0 g (0.048 mol) was added, and the mixture was stirred at room temperature for 1 hour and then refluxed. The reaction product is then purified by vacuum distillation,
t-Butyl isophthalic acid chloride 6.9 g (yield 58
%) Was obtained. Synthesis Example 1 (Synthesis of bisoxadiazole derivative (3-1))

[0067]

Embedded image

2 obtained in Reference Example 1 under an argon atmosphere
Methyl-5 nitrobenzhydrazide (5-1) 8 g (0.0
41 mol) and 5.2 g (0.021 mol) of 5-t-butylisophthalic acid chloride (6-1) obtained in Reference Example 2 were added to 100 ml of dehydrated pyridine, and the mixture was refluxed for 19 hours, and the pyridine was distilled off. After distilling off, the reaction product was added to water, and the deposited precipitate was suction filtered and washed with water to obtain 10.5 g of Compound (7-1)
(Unpurified) was obtained.

Next, 5 g of the above compound (7-1) was added to 100 ml of phosphoryl chloride under an argon atmosphere, and after refluxing for 12 hours, the phosphoryl chloride was distilled off, and water was added to hydrolyze the residual phosphoryl chloride. Further, the precipitated reaction product was washed with water, suction filtered and dried. The product was purified by silica gel column chromatography to obtain 0.9 g of the target compound, the bisoxadiazole derivative (3-1) (yield 8%). The melting point of this compound was 300 ° C. or higher (decomposition). Elemental analysis calculated value (%) C; 62.2, H; 4.4, N; 15.
6, O; 17.8 Found (%) C; 64.3, H; 4.3, N; 15.
8, O; 17.9 Reference Example 3 10 g of nitroterephthalic acid in 40 ml of thionyl chloride
(0.056 mol) was added, and the mixture was stirred at room temperature for 1 hour and then refluxed. Then, the reaction product was purified by distillation under reduced pressure to obtain 7.8 g of nitroterephthalic acid chloride (yield 56%). Synthesis Example 2 (Synthesis of bisoxadiazole derivative (4-1))

[0070]

[Chemical 15]

In an argon atmosphere, the product obtained in Reference Example 1
Methyl-5 nitrobenzhydrazide (5-1) 8 g (0.0
41 mol) and 5.2 g (0.021 mol) of nitroterephthalic acid chloride (6-2) obtained in Reference Example 3 were added to 100 ml of dehydrated pyridine, and the mixture was refluxed for 19 hours, and then pyridine was distilled off. After evaporation, the reaction product was added to water, and the deposited precipitate was suction filtered and washed with water to obtain 9.6 g (unpurified) compound (7-2).

Then, 5 g of the above compound (7-2) was added to 100 ml of phosphoryl chloride under an argon atmosphere, and the mixture was stirred at room temperature for 1 hour.
After refluxing for 2 hours, phosphoryl chloride was distilled off, and water was added to hydrolyze the residual phosphoryl chloride. Further, the precipitated reaction product was washed with water, suction filtered and dried. Purified by silica gel column chromatography, the target compound bisoxadiazole derivative (4-1) (yield 7%) was obtained.
8 g was obtained. The melting point of this compound is 300 ° C or higher (decomposition)
Met. Elemental analysis calculated value (%) C; 54.5, H; 2.8, N; 18.
5, O; 24.2 Found (%) C; 54.6, H; 2.7, N; 18.
3, O; 24.4 << Preparation of Single-Layer Photosensitive Member for Digital Light Source >> Examples 1-2, 10-11 X-type metal-free phthalocyanine (X
φ, Ip = 5.38 eV) or 5 parts by weight of oxotitanyl phthalocyanine (Tiφ, Ip = 5.32 eV),
30 parts by weight of any one of the bisoxadiazole derivatives represented by the formulas (3-1) and (4-1), which is an electron transfer agent,
N, N, N ′, N′-tetrakis (p
-Methylphenyl) -3,3'-dimethylbenzidine (Ip = 5.56 eV) (50 parts by weight) and a binder resin, polycarbonate (100 parts by weight), and a solvent (800).
5 in a ball mill with 5 parts by weight of tetrahydrofuran
The mixture was dispersed for 0 hour to prepare a single-layer type photosensitive layer coating solution. Then, this coating solution is applied to the surface of the aluminum base tube, which is a conductive base material, by a dip coating method,
It was dried with hot air at 60 ° C. for 60 minutes to prepare an electrophotographic photosensitive member having a single-layer type photosensitive layer for a digital light source having a film thickness of 15 to 20 μm. Comparative Examples 1-2 As an electron transfer agent, 3,5-dimethyl-3 ′, 5′-dit-butyl-4,4′-diphenoquinone (MB-DP
Q) Examples 1-2 and 1 except using 30 parts by weight
An electrophotographic photosensitive member having a single-layer type photosensitive layer for a digital light source was produced in the same manner as in 0 to 11. Comparative Example 3 Examples 1 and 10 except that no electron transport agent was blended.
An electrophotographic photosensitive member having a single-layer type photosensitive layer for a digital light source was prepared in the same manner as in. Examples 6 to 9 and 15 to 18 In addition to the charge generating agent, the electron transfer agent, the hole transfer agent and the binder resin, p-benzoquinone (B
Q, redox potential = -0.51 V), 2,6-di-t-butyl-p-benzoquinone (Bu-BQ, redox potential =
-0.51V), 3,5-dimethyl-3 ', 5'-dit
-Butyl-4,4'-diphenoquinone (MB-DPQ,
Redox potential = -0.51 V) and 3,3 ', 5
Examples 1 to 2 above except that 10 parts by weight of any of 5'-tetra-t-butyl-4,4'-diphenoquinone (Bu-DPQ, redox potential = -0.51 V) was mixed and dispersed with a solvent. , 10-11, an electrophotographic photosensitive member having a single-layer type photosensitive layer for a digital light source was prepared. Comparative Examples 8 and 9 Above Examples 6 to 9 and 15 except that 10 parts by weight of 2,5-dichloro-p-benzoquinone (Cl-BQ, redox potential = -0.51 V) was used as an electron-accepting compound.
In the same manner as in # 18 to # 18, an electrophotographic photosensitive member having a single-layer type photosensitive layer for a digital light source was produced.

The following photosensitivity test I was conducted on the electrophotographic photoreceptors of the above-mentioned respective examples and comparative examples to evaluate their sensitivity characteristics. Photosensitivity test I Using a drum sensitivity tester manufactured by GENTEC, an applied voltage was applied to the surface of each of the photoconductors of Examples and Comparative Examples to charge the surface to + 700V. Then, the surface of the photoconductor is irradiated with monochromatic light having a wavelength of 780 nm (half-value width of 20 nm) and a light intensity of 16 μW / cm ² extracted from white light of a halogen lamp which is an exposure light source using a bandpass filter (irradiation time 80 mm Second), and the surface potential at the time when 330 milliseconds have elapsed from the start of exposure was measured as the post-exposure potential V _L (V). Post-exposure potential V _L (V)
The smaller is, the higher the sensitivity of the electrophotographic photosensitive member. The results are shown in Tables 1 and 2 below. << Single-Layer Photosensitive Member for Analog Light Source >> Examples 4 and 13 As the charge generating agent, the substituents R ^{a to} R ^{d of the} general formula (2) are used.
Is a methyl group perylene pigment (Ip = 5.50 eV)
Examples 1-2, 10-1 except that 5 parts by weight were used
In the same manner as in 1, an electrophotographic photosensitive member having a single-layer type photosensitive layer for analog light source was produced. Comparative Example 5 As an electron transfer agent, 3,5-dimethyl-3 ′, 5′-di-t-butyl-4,4′-diphenoquinone (MB-DP
Q) An electrophotographic photosensitive member having a single-layer type photosensitive layer for analog light source was prepared in the same manner as in Examples 4 and 13 except that 30 parts by weight was used. Comparative Example 6 Examples 4 and 13 except that the electron transport agent was not blended.
Similarly to the above, an electrophotographic photosensitive member having a single-layer type photosensitive layer for an analog light source was produced.

The following photosensitivity test II was carried out on the electrophotographic photoreceptors of the above-mentioned respective examples and comparative examples to evaluate their sensitivity characteristics. Photosensitivity test II Using a drum sensitivity tester manufactured by GENTEC, an applied voltage was applied to the surface of each of the photoreceptors of Examples and Comparative Examples to charge the surface to + 700V. Then, the white light of the halogen lamp (light intensity 1
47 μW / cm ² ) is applied to the surface of the photoconductor (irradiation time 5
0 millisecond), and the surface potential at the time when 330 milliseconds have elapsed from the start of exposure was measured as the post-exposure potential V _L (V). The smaller the post-exposure potential V _L (V), the higher the sensitivity of the electrophotographic photosensitive member. The results are shown in Tables 1 and 2 below. << Layered Photoreceptor for Digital Light Source >> Examples 3 and 12 2 parts by weight of X-type metal-free phthalocyanine which is a charge generating agent and 1 part by weight of polyvinyl butyral which is a binder resin, and 120 parts by weight of dichloromethane which is a solvent. At the same time, they were mixed and dispersed in a ball mill to prepare a coating liquid for the charge generation layer. Then, this coating solution is applied to the surface of the aluminum base tube, which is a conductive base material, by a dip coating method, and dried with hot air at 100 ° C. for 60 minutes to give a film thickness of 0.5.
A charge generation layer of μm was formed.

Next, 80 parts by weight of any one of the bisoxadiazole derivatives represented by the formulas (3-1) and (4-1) which are electron transfer agents and 100 parts by weight of polycarbonate which is a binder resin. And were mixed and dispersed with 800 parts by weight of benzene as a solvent in a ball mill to prepare a coating liquid for the charge transport layer. Then, this coating solution is applied on the charge generation layer by a dip coating method, and the coating solution is applied at 90 ° C. for 60 hours.
The film was dried with hot air for 15 minutes to form a charge transport layer having a film thickness of 15 μm, and an electrophotographic photoreceptor having a laminated photosensitive layer for a digital light source was produced. Comparative Example 4 An electrophotographic photosensitive member having a laminated photosensitive layer for a digital light source was produced in the same manner as in Examples 3 and 12 except that 80 parts by weight of MB-DPQ was used as the electron transport agent.

The above-mentioned photosensitivity test I was conducted on the electrophotographic photoreceptors of the above-mentioned respective examples and comparative examples, and their sensitivity characteristics were evaluated. The results are shown in Tables 1 and 2 below. << Layered Photoreceptor for Analog Light Source >> Examples 5 and 14 As the charge generating agent, the substituents R ^{a to} R ^{d of the} general formula (2) are used.
In the same manner as in Examples 3 and 12 except that 2 parts by weight of perylene pigment having a methyl group was used, an electrophotographic photosensitive member having a laminated photosensitive layer for an analog light source was produced. Comparative Example 7 An electrophotographic photosensitive member having a laminated photosensitive layer for an analog light source was produced in the same manner as in Examples 5 and 14 except that 80 parts by weight of MB-DPQ was used as the electron transporting agent.

The above-mentioned photosensitivity test II was conducted on the electrophotographic photoreceptors of the above-mentioned respective examples and comparative examples, and their sensitivity characteristics were evaluated. The results are shown in Tables 1-2.

[0078]

[Table 1]

[0079]

[Table 2]

As is clear from Tables 1 and 2, the photoconductors of the examples using the compounds of the present invention as the electron transfer agent have lower post-exposure potential V _L than the photoconductors of the corresponding comparative examples. Therefore, it can be seen that it has high sensitivity. In addition, the electrophotographic photoreceptors of Examples 6 to 9 and 15 to 18 are different from each other by containing an electron accepting compound having a predetermined redox potential and a specific electron transporting agent excellent in electron transporting property. It is clear that the post-exposure potential is lower than that of the example, and it is understood that it has higher sensitivity.

[0081]

The bisoxadiazole derivative of the present invention has a high electron transporting ability. Therefore, the electrophotographic photosensitive member of the present invention containing such a bisoxadiazole derivative as an electron transfer agent has an effect that the residual potential is remarkably lowered and the sensitivity to charging is high. Therefore, when the photoconductor of the present invention is used, the speed of a copying machine, a printer or the like can be increased.

Further, by adding an electron-accepting compound having a specific oxidation electric potential, the residual potential is further lowered, and a photoreceptor having improved sensitivity can be obtained.

[Brief description of drawings]

FIG. 1 is a graph showing a relationship between a traction voltage (V) and a current (A) for obtaining a redox potential in the present invention.

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[Procedure amendment]

[Submission date] February 21, 1995

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0033

[Correction method] Change

[Correction content]

The charge generating agent, which absorbs light upon exposure to the photoreceptor, produces ion pairs [holes (+) and electrons (-)]. In order for the generated ion pairs to become free carriers and effectively cancel the surface charge, it is preferable that the ion pair recombine and disappear. Here, in the presence of an electron-accepting compound having an oxidation-reduction potential of −0.8 to −1.3 V, LUMO ( of an electron-free molecular orbital)
It is the orbit with the lowest energy level and is excited
The electrons usually move in this orbit. Since the energy level of ) is lower than that of the charge generating agent, when the ion pair is generated, the electron moves to the electron accepting compound and the ion pair is easily separated into the carrier. That is, the electron-accepting compound acts on the charge generation to improve the generation efficiency.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Name of item to be corrected] 0072

[Correction method] Change

[Correction content]

Then, 5 g of the above compound (7-2) was added to 100 ml of phosphoryl chloride under an argon atmosphere, and the mixture was stirred at room temperature for 1 hour.
After refluxing for 2 hours, phosphoryl chloride was distilled off, and water was added to hydrolyze the residual phosphoryl chloride. Further, the precipitated reaction product was washed with water, suction filtered and dried. Purified by silica gel column chromatography, the target compound bisoxadiazole derivative (4-1) (yield 7%) was obtained.
8 g was obtained. The melting point of this compound is 300 ° C or higher (decomposition)
Met. Elemental analysis calculated value (%) C; 54.5, H; 2.8, N; 18.
5, O; 24.2 Found (%) C; 54.6, H; 2.7, N; 18.
3, O; 24.4 << Preparation of Single-Layer Photosensitive Member for Digital Light Source >> Examples 1-2, 10-11 X-type metal-free phthalocyanine (X
φ, Ip = 5.38 eV) or 5 parts by weight of oxotitanyl phthalocyanine (Tiφ, Ip = 5.32 eV),
30 parts by weight of any one of the bisoxadiazole derivatives represented by the formulas (3-1) and (4-1), which is an electron transfer agent,
N, N, N ′, N′-tetrakis (p
-Methylphenyl) -3,3'-dimethylbenzidine (Ip = 5.56 eV) (50 parts by weight) and a binder resin, polycarbonate (100 parts by weight), and a solvent (800).
5 in a ball mill with 5 parts by weight of tetrahydrofuran
The mixture was dispersed for 0 hour to prepare a single-layer type photosensitive layer coating solution. Then, this coating solution is applied to the surface of the aluminum base tube, which is a conductive base material, by a dip coating method,
It was dried with hot air at 60 ° C. for 60 minutes to prepare an electrophotographic photosensitive member having a single-layer type photosensitive layer for a digital light source having a film thickness of 15 to 20 μm. Comparative Examples 1-2 As an electron transfer agent, 3,5-dimethyl-3 ′, 5′-dit-butyl-4,4′-diphenoquinone (MB-DP
Q) Examples 1-2 and 1 except using 30 parts by weight
An electrophotographic photosensitive member having a single-layer type photosensitive layer for a digital light source was produced in the same manner as in 0 to 11. Comparative Example 3 Examples 1 and 10 except that no electron transport agent was blended.
An electrophotographic photosensitive member having a single-layer type photosensitive layer for a digital light source was prepared in the same manner as in. Examples 6 to 9 and 15 to 18 In addition to the charge generating agent, the electron transfer agent, the hole transfer agent and the binder resin, p-benzoquinone (B
Q, redox potential = -0.81V ), 2,6-di-t-butyl-p-benzoquinone (Bu-BQ, redox potential =
-1.30 V ), 3,5-dimethyl-3 ', 5'-di-t
-Butyl-4,4'-diphenoquinone (MB-DPQ,
Redox potential = -0.86 V ) and 3,3 ', 5
Examples 1 to 2 above except that 10 parts by weight of any of 5'-tetra-t-butyl-4,4'-diphenoquinone (Bu-DPQ, redox potential = -0.94 V ) was mixed and dispersed with a solvent. , 10-11, an electrophotographic photosensitive member having a single-layer type photosensitive layer for a digital light source was prepared. Comparative Examples 8 and 9 Examples 6 to 9 and 15 above except that 10 parts by weight of 2,5-dichloro-p-benzoquinone (Cl-BQ, redox potential = -0.51 V) was used as an electron-accepting compound.
In the same manner as in # 18 to # 18, an electrophotographic photosensitive member having a single-layer type photosensitive layer for a digital light source was produced.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Hirofumi Kawaguchi 1-2-2 Tamatsukuri, Chuo-ku, Osaka City, Osaka Prefecture Mita Kogyo Co., Ltd. (72) Yasushi Mizuta 1-2-chome Tamatsukuri, Chuo-ku, Osaka City, Osaka Prefecture No. 28 Inside Mita Industry Co., Ltd.

Claims (5)

[Claims] 1. General formula (1): (In the formula, R ¹ represents an alkyl group, an alkoxyl group or a halogen atom, R ² represents an alkyl group or a nitro group, m is an integer of 0 to 3, and n is an integer of 0 to 2.) Bisoxadiazole derivative. 2. An electrophotographic photoreceptor having an organic photosensitive layer provided on a conductive substrate, wherein the organic photosensitive layer has the following general formula (1):
An electrophotographic photoreceptor containing the bisoxadiazole derivative represented by the formula (1) as an electron transfer agent. Embedded image (In the formula, R ¹ represents an alkyl group, an alkoxyl group, or a halogen atom, R ² represents an alkyl group or a nitro group, m is an integer of 0 to 3, and n is an integer of 0 to 2.) 3. The organic photosensitive layer is -0.8 to -1.3V.
The electrophotographic photosensitive member according to claim 2, which contains the electron-accepting compound having the redox potential of. 4. The electrophotographic photosensitive member according to claim 2, wherein the organic photosensitive layer contains a phthalocyanine pigment as a charge generating agent. 5. The organic photosensitive layer contains a perylene pigment represented by the following general formula (2) as a charge generating agent.
And the electrophotographic photosensitive member described in 3. Embedded image (In the formula, R ^a , R ^b , R ^c , and R ^d are the same or different and represent a hydrogen atom, an alkyl group, an alkoxyl group, or an aryl group.)