JPH08151382A - Dioxodiimidazopyrazine derivative and electrophotographic receptor using the same - Google Patents

Abstract

PURPOSE: To obtain a new compound having excellent electron transporting properties especially in a low electric field and providing an electrophotographic receptor with high sensitivity as an electron transporting agent due to excellent solubility in a solvent, compatibility with a binder resin and matching with an electric charge generating agent. CONSTITUTION: This compound is shown by formula I (R<1> is an alkyl, an aryl or an aralkyl) such as a compound of formula II. The compound, for example, iis obtained by reacting an acid halide of formula III (X is a halogen) with a compound of the formula R-OH such as n-butanol in a solvent such as THF in the presence of a catalyst such as triethylamine at -15 to 80 deg.C for 10 minutes to 2 hours.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dioxodiimidazopyrazine 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 dioxodiimidazopyrazine 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 dioxodiimidazopyrazine 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]

It has been found that the dioxodiimidazopyrazine derivative represented by the formula (wherein R represents an alkyl group, an aryl group or an aralkyl group) has a higher electron transporting ability than conventional diphenoquinone compounds. Has been completed. The dioxodiimidazopyrazine derivative represented by the above general formula (1) has good solubility in a solvent and compatibility with a binder resin, and good matching with a charge generating agent. The injection is performed smoothly, 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 transporting agent in an electrophotographic photoreceptor, a highly sensitive organic photoreceptor can be provided. Furthermore, 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. As the substituent R in the general formula (1),
For example, methyl, ethyl, n-propyl, isopropyl,
t-butyl, pentyl, hexyl, etc. have 1 to 6 carbon atoms
And an aryl group such as a phenyl group and a naphthyl group; and an aralkyl group such as a benzyl, benzhydryl, trityl and phenethyl group.

The dioxodiimidazopyrazine derivative (1) of the present invention is synthesized, for example, as shown below.

[0011]

Embedded image

(In the formula, R is the same as above, and X represents a halogen atom.) Examples of the solvent used in the reaction include tetrahydrofuran (THF), dimethylformamide, chloroform, diethyl ether, toluene, xylene and the like. Can be mentioned. The reaction is trimethylamine, triethylamine,
It is usually carried out in the presence of a catalyst such as pyridine, dimethylaniline, or triphenylamine at a temperature of -15 to 80 ° C for about 10 minutes to 2 hours.

In the above formula, the acid halide represented by the general formula (3) used is one manufactured by Nippon Soda Co., Ltd. Such compounds
By esterifying (3) to a compound represented by the following formulas (1-1) to (1-3), the electron-transporting ability is high and the compound is dissolved in a solvent, as described in Examples below. It is possible to obtain an electron transporting material having high properties and high compatibility with the binder resin.

[0014]

[Chemical 6]

The electrophotographic photoreceptor of the present invention comprises an electroconductive substrate and an organic photosensitive layer provided on the electroconductive substrate. The binder resin in the organic photosensitive layer is a dioxodione represented by the general formula (1). It is characterized by containing an imidazopyrazine derivative 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 dioxodiimidazopyrazine 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 withdrawal from the charge generating agent is efficiently performed. As a result, the sensitivity of the photoconductor is further improved.

On the other hand, the laminated electrophotographic photoreceptor of the present invention is
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 contains a dioxodiimidazopyrazine derivative represented by the general formula (1) as an electron transport agent. . 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 above-mentioned general formula (1).
It is preferable that the dioxodiimidazopyrazine derivative represented by In addition, 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 contains the dioxodiimidazo compound represented by the general formula (1) as an electron transport agent. A pyrazine derivative is contained, and the charge generation layer contains -0.8 to -1.
An electron accepting compound having a redox potential of 3V may be contained.

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 also necessary that carrier traps due to impurities do not occur when 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 greater than -0.8 V is used, the separated free carriers are dropped to a level that cannot be detrapped, resulting in carrier traps. 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 transporting agents, the ionization potential is 4.8 to 5.6 eV.
It is preferable to use one having an electric field strength of 3 × 10 ⁵ V
Those having a mobility of 1 × 10 ⁻⁶ cm ² / V · sec or more in / 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, the bulky substituent is introduced into the dioxodiimidazopyrazine 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
Examples include -ethyl-3-carbazolylaldehyde-N, N'-diphenylhydrazone and 4- [N, N-bis (p-toluyl) amino] -β-phenylstilbene.

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 compounds 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 (5) to (8).

[0034]

[Chemical 7]

[0035]

Embedded image

(In each formula, R ¹ , R ² , R ³ , R ⁴ , R ⁵
And R ⁶ 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 (5) to (8) 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 (5) include 3,3 ', 5,5'-tetramethyl-4,4'-diphenoquinone, 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.

Examples of the charge generating agent used in the present invention include selenium, selenium-tellurium, amorphous silicon, pyrylium salts, azo pigments, ansanthuron pigments, phthalocyanine pigments, perylene pigments, naphthalocyanine pigments, 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
(2):

[0041]

[Chemical 9]

(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 alkoxy group or an aryl group.) A compound represented by the following is preferably used. . Examples of the alkyl group, alkoxy group and aryl group 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, since the above perylene pigment (2) 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 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 transfer agent is dissolved or dispersed in a suitable solvent together with a charge generating agent, a hole transfer 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 case of a 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 dioxodiimidazopyrazine derivative (1), the derivative (1) is added in an amount of 0.5 to 50 parts by weight, preferably 1 to 40 parts by weight, based on 100 parts by weight of the binder resin. It is suitable to blend in.

The electron-transporting agent and the binder resin constituting the charge-transporting layer can be used in various proportions within a range that does not hinder the transport of charge and a 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 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, may be added to each of the single-layer type and laminated type photosensitive layers as long as they do not adversely affect the electrophotographic properties. 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 above general formula, 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,
Examples thereof include maleic anhydride and dibromomaleic anhydride.

As the conductive substrate used in the photoreceptor of the present invention, various materials having conductivity 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 roll mill, ball mill, attritor, paint shaker or 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.

[0055]

EXAMPLES Hereinafter, the dioxodiimidazopyrazine derivative of the present invention and the electrophotographic photoreceptor using the same will be described with reference to Synthesis Examples, Examples and Comparative Examples. << Synthesis of Dioxodiimidazopyrazine Derivative >> Synthesis Example The compound (1-1) exemplified above was synthesized as shown in the following formula.

[0056]

[Chemical 10]

1.3 g (0.0128 mol) of triethylamine was added to 10 ml of n-butanol (4-1), and the mixture was stirred at room temperature. Then, 2.0 g of compound (3-1) (0.006
4 mol) to 10 ml of dehydrated tetrahydrofuran (THF)
Was dissolved in, and was added dropwise to a mixed solution of n-butanol and triethylamine and heated for 2 hours. After cooling, n-butanol and THF were distilled off, the obtained solid was purified by silica gel column chromatography (developing solvent: chloroform), and 0.4 g of the target dioxodiimidazopyrazine derivative (1-1) was obtained. (Yield 16.1%) was obtained. The melting point of this compound (1-1) was 300 ° C. or higher (decomposition).

The infrared absorption spectrum of the compound (1-1) is shown in FIG.
Shown in << Preparation of Single-Layer Photosensitive Member for Digital Light Source >> Examples 1 and 2 X-type metal-free phthalocyanine (X
φ, Ip = 5.38 eV) or 5 parts by weight of oxotitanyl phthalocyanine (Tiφ, Ip = 5.32 eV),
Dioxodiimidazopyrazine derivatives (1
-1) 30 parts by weight and N, N, N ', which is a hole transfer material,
N'-tetrakis (p-methylphenyl) -3,3'-
50 parts by weight of dimethylbenzidine (Ip = 5.56 eV) and 100 parts by weight of polycarbonate which is a binder resin are mixed and dispersed with 800 parts by weight of tetrahydrofuran which is a solvent for 50 hours in a ball mill to obtain a single layer type photosensitive layer. A coating liquid was prepared. Then, this coating liquid is applied to the surface of an aluminum base tube which is a conductive base material by a dip coating method, dried by hot air at 100 ° C. for 60 minutes, and a single layer type for a digital light source having a film thickness of 15 to 20 μm. An electrophotographic photoreceptor having a photosensitive layer was produced. Comparative Examples 1-2 As an electron transfer agent, 3,5-dimethyl-3 ′, 5′-dit-butyl-4,4′-diphenoquinone (MB-DP
Q) An electrophotographic photoreceptor having a single-layer type photosensitive layer for a digital light source was produced in the same manner as in Examples 1 and 2 except that 30 parts by weight was used. Comparative Example 3 An electrophotographic photosensitive member having a single-layer type photosensitive layer for a digital light source was produced in the same manner as in Example 1 except that the electron transfer agent was not added. Examples 6 to 9 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. An electrophotographic photosensitive member having a single-layer type photosensitive layer for a digital light source was prepared in the same manner as in. Comparative Example 8 In the same manner as in Examples 6 to 9 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. 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 Table 1 below. << Single-Layer Photoreceptor for Analog Light Source >> Example 4 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)
An electrophotographic photosensitive member having a single-layer type photosensitive layer for an analog light source was produced in the same manner as in Examples 1 and 2 except that 5 parts by weight was used. 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 an analog light source was produced in the same manner as in Example 4 except that 30 parts by weight was used. Comparative Example 6 An electrophotographic photosensitive member having a single-layer type photosensitive layer for an analog light source was produced in the same manner as in Example 4 except that the electron transfer agent was not added.

The following photosensitivity test II was conducted 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 Table 1 below. << Layered Photoreceptor for Digital Light Source >> Example 3 2 parts by weight of X-type metal-free phthalocyanine that is a charge generating agent and 1 part by weight of polyvinyl butyral that is a binder resin, and 120 parts by weight of dichloromethane that is a solvent are ball-milled. Was mixed and dispersed in to prepare a coating solution 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 the dioxodiimidazopyrazine derivative (1-1), which is an electron transfer agent, and 100 parts by weight of polycarbonate, which is a binder resin, were mixed with 80 parts by weight of a solvent.
A coating solution for a charge transport layer was prepared by mixing and dispersing with 0 part by weight of benzene in a ball mill. Then, this coating solution is applied on the charge generation layer by a dip coating method and dried by hot air at 90 ° C. for 60 minutes to give a film thickness of 15 μm.
The charge transport layer of 1 was formed to prepare an electrophotographic photoreceptor having a laminated photosensitive layer for a digital light source. Comparative Example 4 An electrophotographic photoreceptor having a laminated photosensitive layer for a digital light source was produced in the same manner as in Example 3 except that 80 parts by weight of MB-DPQ was used as the electron transport agent.

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

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 Table 1.

[0064]

[Table 1]

As is clear from Table 1, the photoconductors of the examples using the compounds of the present invention as the electron transfer agent had lower post-exposure potential V _L than the photoconductors of the comparative examples corresponding thereto. Therefore, it can be seen that it has high sensitivity. In addition, the electrophotographic photoreceptors of Examples 6 to 9 contain an electron-accepting compound having a predetermined redox potential and a specific electron-transporting agent having an excellent electron-transporting property, so that the electrophotographic photoreceptors are more than those of other Examples. Furthermore, it is clear that the potential after exposure is lowered, and it can be seen that it has higher sensitivity.

[0066]

The dioxodiimidazopyrazine derivative of the present invention has a high electron transporting ability. Therefore, the electrophotographic photoreceptor of the present invention containing such a dioxodiimidazopyrazine derivative as an electron transfer agent has an effect that the residual potential is remarkably lowered and it has a high sensitivity to charging.
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 photosensitive member 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.

FIG. 2 is an infrared absorption spectrum of the compound (1-1) obtained in Synthesis Example.

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[Procedure amendment]

[Submission date] February 21, 1995

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] 0023

[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] 0058

[Correction method] Change

[Correction content]

The infrared absorption spectrum of the compound (1-1) is shown in FIG.
Shown in << Preparation of Single-Layer Photosensitive Member for Digital Light Source >> Examples 1 and 2 X-type metal-free phthalocyanine (X
φ, Ip = 5.38 eV) or 5 parts by weight of oxotitanyl phthalocyanine (Tiφ, Ip = 5.32 eV),
Dioxodiimidazopyrazine derivatives (1
-1) 30 parts by weight and N, N, N ', which is a hole transfer material,
N'-tetrakis (p-methylphenyl) -3,3'-
50 parts by weight of dimethylbenzidine (Ip = 5.56 eV) and 100 parts by weight of polycarbonate which is a binder resin are mixed and dispersed with 800 parts by weight of tetrahydrofuran which is a solvent for 50 hours in a ball mill to obtain a single layer type photosensitive layer. A coating liquid was prepared. Then, this coating liquid is applied to the surface of an aluminum base tube which is a conductive base material by a dip coating method, dried by hot air at 100 ° C. for 60 minutes, and a single layer type for a digital light source having a film thickness of 15 to 20 μm. An electrophotographic photoreceptor having a photosensitive layer was produced. Comparative Examples 1-2 As an electron transfer agent, 3,5-dimethyl-3 ′, 5′-dit-butyl-4,4′-diphenoquinone (MB-DP
Q) An electrophotographic photoreceptor having a single-layer type photosensitive layer for a digital light source was produced in the same manner as in Examples 1 and 2 except that 30 parts by weight was used. Comparative Example 3 An electrophotographic photosensitive member having a single-layer type photosensitive layer for a digital light source was produced in the same manner as in Example 1 except that the electron transfer agent was not added. Examples 6 to 9 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 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. An electrophotographic photosensitive member having a single-layer type photosensitive layer for a digital light source was prepared in the same manner as in. Comparative Example 8 In the same manner as in Examples 6 to 9 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. An electrophotographic photosensitive member having a single-layer type photosensitive layer for a digital light source was produced.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location // (C07D 487/14 233: 56 241: 18) (72) Inventor Hirofumi Kawaguchi Osaka City, Osaka Prefecture Chuo-ku Tamakozo 1-228 Mita Kogyo Co., Ltd. (72) Inventor Yasushi Mizuta 1-2-2 Tazozo Chuo-ku, Osaka-shi, Osaka Mita Kogyo Co., Ltd.

Claims (5)

[Claims] 1. General formula (1): (In the formula, R represents an alkyl group, an aryl group or an aralkyl group.) A dioxodiimidazopyrazine derivative represented by the formula: 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 dioxodiimidazopyrazine derivative represented by: Embedded image (In the formula, R represents an alkyl group, an aryl group or an aralkyl group.) 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.
Alternatively, the electrophotographic photoconductor of item 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.)