JP3121143B2 - Electrophotographic photoreceptor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic photosensitive member used in an image forming apparatus utilizing an electrophotographic method, such as an electrostatic copying machine or a laser beam printer.

[0002]

2. Description of the Related Art An electrophotographic method such as the Carlson process includes a step of uniformly charging the surface of an electrophotographic photosensitive member by corona discharge, and a step of exposing the charged surface of the electrophotographic photosensitive member to an electrostatic latent image. An exposure step of forming an image, a developing step of bringing a developer into contact with the formed electrostatic latent image, and developing the electrostatic latent image into a toner image with toner contained in the developer; And a fixing step of fixing the transferred toner image, and after the transfer step,
A cleaning step of removing toner remaining on the photoconductor.

As the electrophotographic photosensitive member used in the above electrophotographic method, an inorganic photosensitive member using a photosensitive layer containing an inorganic material such as selenium and an organic photosensitive member using a photosensitive layer containing an organic material are exemplified. is there. Organic photoreceptors are inexpensive and pollution-free compared to inorganic photoreceptors, and because of their diverse molecular structures, they have many advantages such as greater freedom in functional design and higher productivity. In recent years, extensive research has been advanced.

In such organic photoreceptors, generally, a function-separated type photosensitive layer containing a charge generating material for generating charges by light irradiation and a charge transporting material for transporting the generated charges is often used. . In order to satisfy various conditions desired for such an organic photoreceptor, it is necessary to appropriately select materials to be combined such as a charge generation material and a charge transport material.

As the charge transport material, various kinds of substances have been studied, and many substances such as polyvinyl carbazole, oxadiazole compounds, pyrazoline compounds and hydrazone compounds have been proposed. Since these charge transporting materials are hole transporting materials, a charge generation layer and a charge transporting layer are formed on a conductive substrate, which is one of the function-separated type photoreceptors that are currently the mainstream of organic photoreceptors. In the case of a stacked type photoreceptor in which layers are sequentially stacked, a negative charging process is inevitably required.

However, in the case of a negatively charged organic photoreceptor, there is a possibility that the environment is polluted by the generation of ozone or the photoreceptor is oxidized and deteriorated. It requires a system for discarding ozone in the image forming apparatus, and has a drawback that the process and the system are complicated. The use of an electron transporting material as a charge transporting material has been studied to eliminate these drawbacks, and an electrophotographic photoreceptor that can be used in positive charge, using a compound having a diphenoquinone skeleton as the electron transporting material, has been studied. It has been proposed (Japanese Patent Laid-Open No. 1-20
No. 6349).

The compound having a diphenoquinone skeleton is an electron acceptor having a non-polarized π electron system,
Electrons can be transported by an electron transfer reaction involving an anion radical state. By the way, if a photoreceptor having both positively and negatively charged characteristics can be used, the application range of the photoreceptor can be further expanded. Such a photoreceptor can be used for both positive and negative charging by including an electron transporting material having a diphenoquinone structure as a charge transporting material and a polysilane-based hole transporting material in the photosensitive layer. It has also been studied to obtain a photosensitive member having excellent performance.

[0008]

The diphenoquinone derivatives are said to exhibit good transportability, but have poor sensitivity for use in high-speed copiers and the like, and have not yet been sufficiently satisfactory in practical use. . The present inventors have found that among various diphenoquinone derivatives, diphenoquinone derivatives containing a substituent in a specific positional relationship have a remarkably superior sensitivity surface as compared with diphenoquinone derivatives conventionally known as electron transport agents. Was found.

In order to produce an organic photoreceptor using various materials, it is necessary to select a material having good matching so as to satisfy electrophotographic characteristics. For example, even if charge transporting materials having high charge transporting ability are combined, it is not always possible to obtain good electrophotographic properties.In a system in which a hole transporting material and an electron transporting material coexist as charge transporting materials, Care must be taken in the formation of mobile complexes. That is, when the charge transfer complex is formed, recombination occurs between the holes and the electrons, and the transfer of charges is reduced as a whole. Further, when the energy gap between the HOMO of the hole transport material and the LUMO of the electron transport material coincides with the wavelength energy of the main exposure and the erasing light applied to the photoreceptor, light is absorbed by the charge transfer complex, and the charge is transferred. This leads to a drastic decrease in generation efficiency.

It is inferred that the formation of the charge transfer complex has a causal relationship with the way the electron clouds of the hole transport material and the electron transport material overlap. An object of the present invention is to provide an electrophotographic photoreceptor having high sensitivity and excellent repetition characteristics and residual potential characteristics.

[0011]

The following general formula (1) as an electron transport material is provided on a conductive substrate.

[0012]

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(Wherein R1, R2, R3 and R4 are
It represents a hydrogen atom, an alkyl group, an alkoxy group, or an aryl group which may have a substituent. However, two of R1, R2, R3 and R4 are the same group , and the same group and another
The two are different groups . A diphenoquinone-based compound represented by the following formula (2):

[0014]

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Wherein R5, R6, R7 and R8 are
Represents a hydrogen atom, an alkyl group or an alkoxy group, each of which may be substituted plurally, and n represents an integer of 1 to 2; )
It has been found that a photosensitive layer containing the compound represented by the formula (1) may be provided, and the present invention has been completed. According to the present invention, the diphenoquinone derivative having the structure represented by the general formula (1) has significantly improved sensitivity and residual potential while maintaining substantially the same chargeability and repetition characteristics as those of a known diphenoquinone derivative as an electron transporting agent. It is based on the knowledge to show.

[0016] Conventionally, more soluble in the solvent, thus compatibility with the binder resin is good, and moreover the best diphenoquinone derivatives in the electron transport performance, ^{3,3-dimethyl-3,}
5 ^, -ditertbutyl-4,4 ^, -diphenoquinone (D
MDB) That is, the following equation (a)

[0017]

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Derivatives are known. This DMDB
Among the diphenoquinone derivatives, although having high charging characteristics and excellent sensitivity, further improvement in sensitivity is necessary for use in high-speed copying machines, etc., and they are still sufficiently satisfactory in practical use. You don't get it. In contrast, when the diphenoquinone derivative having the structure represented by the general formula (1) is used according to the present invention, the sensitivity and the residual potential are significantly improved while maintaining the charging characteristics and the repetition characteristics at the same level as DMDB. (See the example described later).

The fact that the diphenoquinone derivative used in the present invention exhibits the above-mentioned improvement has been found as a phenomenon as a result of many experiments. However, since this derivative has lower symmetry, it can be found in the photosensitive layer. It is presumed that diphenoquinone molecules are effectively distributed in the same volume, and that it works advantageously for conducting hopping conduction of electrons.

Therefore, the present inventors have selected a specific hole transporting material for the diphenoquinone-based compound and intended to obtain satisfactory electrophotographic characteristics with high performance. Various studies were conducted. Matching by selecting the compound represented by the general formula (1) as the specific electron transport material according to the present invention and the compound represented by the general formula (2) as the specific hole transport material Although the action of is not clear, from the comparison of Examples and Comparative Examples described later, as a result, sensitivity, repetition characteristics,
It is understood that this leads to an improvement in residual potential characteristics.

That is, even if the output of the exposure lamp, which is mounted as a standard in the copying machine, is not increased, no problem such as fogging occurs, which leads to a longer life of the exposure lamp and a reduction in power consumption. It is estimated to be.

[0022]

Preferred Embodiment As the charge generation material , conventionally known charge generation materials can be used, and examples thereof include selenium, selenium-tellurium, selenium-arsenic, amorphous silicon, pyrylium salts, azo pigments, perylene pigments, Anthanthrone-based pigments, phthalocyanine-based pigments, indigo-based pigments, triphenylmethane-based pigments, sulene-based pigments, toluidine-based pigments, pyrazoline-based pigments, quinacridone-based pigments, pyrrolopyrrole-based pigments, and the like, preferably metal-free phthalocyanine ,
Copper phthalocyanine, oxotitanyl phthalocyanine, and the like are preferable, and particularly, a material having an ionization potential of 5.3 eV to 5.6 eV (measurement by a photoelectron analyzer under atmospheric pressure (manufactured by Riken Keiki Co., Ltd., AC-1)) is preferable. The following are exemplified as particularly preferable. X-type metal-free phthalocyanine (IP = 5.38e
V) β-type metal-free phthalocyanine (IP = 5.32e
V) Oxotitanyl phthalocyanine (IP = 5.32 eV) 1,4-dithioketo-3,6-diphenyl-pyrrolo-
(3, 4-C) pyrrole (IP = 5.46 eV) N, N-bis ^{(3, 5,} - dimethylphenyl) perylene-3,4,9,10-tetracarboxylic diimide (I
(P = 5.60 eV) Charge transporting material The electron transporting material represented by the general formula (1) and the hole transporting material represented by the general formula (2) are used.

In the diphenoquinone compound represented by the general formula (1), examples of the alkyl group corresponding to R1, R2, R3 and R4 include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group and an isobutyl group. Group, t-butyl group, pentyl group, hexyl group and the like. Examples of the alkoxy group include a methoxy group,
Examples include an ethoxy group, a propoxy group, an isopropoxy group, a butoxy group, a t-butoxy group, and a hexyloxy group.

As the aryl group, for example, a phenyl group,
Examples include a tolyl group, a xylyl group, a biphenyl group, a naphthyl group, an anthryl group, and a phenanthryl group. Examples of the substituent to be substituted on each of the above groups include a methyl group, an ethyl group, an isopropyl group, a propyl group, a butyl group, an isobutyl group,
t-butyl group, pentyl group, methoxy group, ethoxy group,
Examples include a propoxy group, an isopropoxy group, a butoxy group, an isobutoxy group, and a t-butoxy group.

As the diphenoquinone derivative represented by the general formula (1), those represented by the following formulas (3), (4) and (5) are used.

[0026]

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(Wherein R 1 ^′ , R 2 ^′ and R 3 ^′ are different
Represents a hydrogen atom, an alkyl group, an alkoxy group, and an aryl group which may have a substituent. ) The general formula (3),
As specific examples of the diphenoquinone derivatives represented by (4) and (5), compounds having the groups shown in Table 1 as groups of R1 ^{′ to} R3 ^{′ in} the respective formulas are exemplified.

[0028]

[Table 1]

The diphenoquinone derivatives represented by the general formulas (3), (4) and (5) can be used alone or
Alternatively, they may be used as a mixture. The diphenoquinone derivative represented by the general formula (3), (4) or (5) can be synthesized by conventionally known various methods. For example, the diphenoquinone derivative is represented by the general formula (3). The diphenoquinone derivative has the following formula (i)

[0030]

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[0031] (wherein ^R1, the formula (3) similar to)
And a disubstituted phenol represented by the following formula (ii):

[0032]

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[0033] (wherein ^{R2,, R3,} is the general formula (3) similar to) the copper salt in a polar solvent to a disubstituted phenol represented by - and molecular oxygen in the presence of a tertiary amine complex catalyst Synthesized by contact. The diphenoquinone derivative represented by the general formula (4) is replaced by the following formulas (iii) and (iv) instead of the formulas (i) and (ii).
Except that the disubstituted phenol represented by the formula is used.

[0034]

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[0035] (wherein ^{R1,, R2,, R3,} is the general formula (4) similar to) Further, diphenoquinone derivative represented by the above general formula (5) is replaced by the formula (i) (ii) And the following equation (v)
It is synthesized in the same manner as described above, except that the disubstituted phenol represented by (vi) is used.

[0036]

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(In the formula, R 1 ^, R 2 ^, R 3 ^, are the same as those in the general formula (5).) In the hole transporting material represented by the general formula (2), R 5, R 6, R 7 and R 8 in the formula Examples of the alkyl group and the alkoxy group corresponding to the above include those similar to the aforementioned general formula (1). Specific examples of the compound represented by the general formula (2) include the following formulas (C) to (E).
Are represented.

[0038]

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The compound (2) can be synthesized by conventionally known various methods. The compounds represented by the general formulas (1) and (2), which are charge transport materials, can be used in combination with other conventionally known charge transport materials. As a conventionally known charge transporting material, various electron withdrawing compounds and electron donating compounds can be used.

As the electron withdrawing compound, for example, 2,
^{6-dimethyl-2,, 6,} - di tert- dibutyl phenoxide diphenoquinone derivatives non like, malononitrile, thiopyran compounds, tetracyanoethylene, 2,
4,8-trinitrothioxanthone, 3,4,5,7-
Tetranitro-9-fluorenone, dinitrobenzene,
Examples thereof include dinitroanthracene, dinitroacridine, nitroanthraquinone, dinitroanthraquinone, succinic anhydride, maleic anhydride, and dibromomaleic anhydride.

As the electron donating compound, 2,5
Oxadiazole compounds such as -di (4-methylaminophenyl) and 1,3,4-oxadiazole; 9- (4
Styryl compounds such as -diethylaminostyryl) anthracene, carbazole compounds such as polyvinylcarbazole, pyrazoline compounds such as 1-phenyl-3- (p-dimethylaminophenyl) pyrazoline, hydrazone compounds, triphenylamine compounds, indole Compounds, oxazole compounds, isoxazole compounds, thiazole compounds, thiadiazole compounds,
Nitrogen-containing cyclic compounds such as imidazole compounds, pyrazole compounds and triazole compounds, and condensed polycyclic compounds are exemplified.

These charge transporting materials are used alone or as a mixture of two or more. Note that when a charge transporting material having a film forming property such as polyvinyl carbazole is used,
A binder resin is not always necessary. Examples of the binder resin a binder resin, can be used various resins. For example, styrene polymers, styrene-butadiene copolymers, styrene-acrylonitrile copolymers, styrene-maleic acid copolymers, acrylic copolymers, styrene-acrylic acid copolymers, polyethylene, ethylene-vinyl acetate copolymer , Chlorinated polyethylene, polyvinyl chloride, polypropylene, vinyl chloride-vinyl acetate copolymer, polyester alkyd resin, polyamide, polyurethane, polycarbonate, polyarylate, polysulfone, diallyl phthalate resin, ketone resin, polyvinyl butyral resin, polyether resin, Thermoplastic resin such as polyester resin, silicone resin, epoxy resin,
Examples include phenolic resins, urea resins, melamine resins, other thermosetting resins having a cross-linking property, and photo-curing resins such as epoxy acrylate and urethane-acrylate.
These binder resins can be used alone or in combination of two or more. As the conductive substrate on which the conductive substrate photosensitive layer is formed, various materials having conductivity can be used, for example, aluminum, copper, tin, platinum, silver, vanadium, molybdenum, chromium, cadmium, titanium, Examples thereof include simple metals such as nickel, palladium, indium, stainless steel, and brass; plastic materials on which the above metals are deposited or laminated; glass coated with aluminum iodide, tin oxide, indium oxide, and 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. In addition, the conductive substrate preferably has sufficient mechanical strength when used. Additives The organic photosensitive layer may contain additives such as a sensitizer, a fluorene compound, an antioxidant, a deterioration inhibitor such as an ultraviolet absorber, and a plasticizer.

For example, suitable antioxidants are:

[0045]

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[0046]

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When the sterically hindered phenolic antioxidant is blended in an amount of 0.1 to 50% by weight based on the total solid content,
It has been found that the durability of the photosensitive layer can be significantly improved without adversely affecting the electrophotographic characteristics. Further, in order to improve the sensitivity of the charge generation layer, for example, terphenyl,
Known sensitizers such as halonaphthoquinones and acenaphthylene may be used in combination with the charge generating material. Configuration of Photoreceptor The photoreceptor of the present invention can be applied to a single-layer type or a multilayer type as a photosensitive layer. However, the effect of the combination of the electron transporting material and the hole transporting material is more pronounced in a single layer type photosensitive layer in which both materials are contained in the same layer. It can be said that application to an electrophotographic photosensitive member having a photosensitive layer is more preferable.

In order to obtain a single-layer type photoreceptor, a charge generating material, a compound represented by the general formula (1) which is an electron transport material, and a compound represented by the general formula (2) which is a hole transport material are used. A photosensitive layer containing the compound represented by the formula, a binder resin and the like may be formed on the conductive substrate by means such as coating. That is, the principle of generating a charge image in the single-layer system is that, when charges (holes / electrons) are generated in the charge generating material by exposure, electrons are injected into the electron transporting material, and holes are injected into the hole transporting material. Then, each injected charge (hole / electron) is transferred in each transport material without being trapped on the way, and finally transported to the surface of the photosensitive layer or the surface of the conductive substrate. Things.

That is, in the single-layer type photoreceptor as described above,
Not only can the trapping of electric charge be suppressed and the sensitivity can be improved, but it can also be used as a dual charged photoreceptor and has a wide application range. Further, the single-layer type photoreceptor does not need to be coated twice on the photosensitive layer due to its constitution, so that the productivity is improved. Further, in order to obtain a laminated photoreceptor, a charge generation layer containing a charge generation material is formed on a conductive substrate by means such as vapor deposition or coating, and the above-mentioned electron transport material, which is an electron transport material, is formed on the charge generation layer. What is necessary is just to form a charge transport layer containing the compound represented by the general formula (1), the compound represented by the general formula (2) as a hole transport material, and a binder resin. Conversely, a charge transport layer may be formed on a conductive substrate, and then a charge generation layer may be formed.

The above-mentioned laminated type photoreceptor can be used as a dual charged photoreceptor and has a wide range of applications. Further, a hole transport layer containing a compound represented by the above general formula (2), which is a hole transport material, and a binder resin is formed on the conductive substrate, and vapor deposition is performed on the hole transport layer. Alternatively, a charge-generating layer containing a charge-generating material is formed by means such as coating, and an electron-transporting material represented by the general formula (1)
An electron transport layer containing the compound represented by and a binder resin may be formed.

The above-mentioned laminated type photoreceptor is of a positive charging type. Conversely, the electron transport layer may be formed on the conductive substrate, and then the charge generation layer and the hole transport layer may be sequentially laminated. The above-mentioned laminated photoreceptor is of a negative charging type. Further, a protective layer may be provided on the organic photosensitive layer, or an intermediate layer may be provided between the organic photosensitive layer and the conductive substrate. Single layer type photoreceptor When the organic photosensitive layer is formed as a single layer, the thickness of the organic photosensitive layer is preferably from 10 to 50 μm, more preferably from 15 to 30 μm.

The content of the charge generation material is preferably in the range of 1 to 20 parts by weight, more preferably 1 to 20 parts by weight, based on 100 parts by weight of the binder resin of the organic photosensitive layer.
10 parts by weight. When the content of the charge generating material is less than 1 part by weight, the obtained photoreceptor has a low charge generating ability. Conversely, if the content of the charge generating material exceeds 20 parts by weight, the abrasion resistance of the resulting photoreceptor may be reduced.

The content of the electron transporting material represented by the general formula (1) is preferably in the range of 10 to 100 parts by weight based on 100 parts by weight of the binder resin of the organic photosensitive layer. More preferably, it is 20 to 70 parts by weight. When the content of the electron transporting material is less than 10 parts by weight, the sensitivity and repetition characteristics of the obtained photoreceptor are deteriorated. Conversely, if the content of the electron transport material exceeds 100 parts by weight, the abrasion resistance of the obtained photoreceptor may be reduced.

The content of the hole transporting material represented by the above general formula (2) is preferably in the range of 10 to 100 parts by weight based on 100 parts by weight of the binder resin of the organic photosensitive layer. And more preferably 20 to 70 parts by weight. When the content of the hole transport material is less than 10 parts by weight, the sensitivity of the obtained photoreceptor is deteriorated. Conversely, when the content of the hole transport material exceeds 100 parts by weight, the abrasion resistance of the obtained photoconductor may be reduced.

The content of the electron transporting material represented by the above general formula (1) is 20 to 80% by weight in the charge transporting material.
And particularly preferably 30 to 70% by weight. When the content of the electron transporting material in the charge transporting material is less than 20% by weight, the sensitivity of the obtained photoreceptor,
Poor repetition characteristics. On the other hand, when the content of the electron transport material exceeds 80% by weight, the sensitivity of the obtained photoreceptor deteriorates. When the organic photosensitive layer is formed of a charge generation layer and a charge transport layer, the thickness of the charge generation layer is preferably from 0.1 to 5 μm, and more preferably from 0.5 to 2 μm. . The thickness of the charge transport layer is preferably from 10 to 50 μm, and more preferably from 15 to 30 μm.

The content of the charge generation material is preferably in the range of 50 to 500 parts by weight, more preferably 100 to 300 parts by weight, based on 100 parts by weight of the binder resin of the charge generation layer. is there. When the content of the charge generating material is less than 50 parts by weight, the obtained photoreceptor has a small charge generating ability, and when the content of the charge generating material exceeds 500 parts by weight, the mechanical strength of the obtained photoreceptor is low. May drop.

The content of the electron transporting material represented by the general formula (1) is preferably from 10 to 100 parts by weight based on 100 parts by weight of the binder resin of the charge transporting layer. More preferably, it is 20 to 70 parts by weight. When the content of the electron transporting material is less than 10 parts by weight, the sensitivity and repetition characteristics of the obtained photoreceptor are deteriorated. Conversely, if the content of the electron transport material exceeds 100 parts by weight, the abrasion resistance of the obtained photoreceptor may be reduced.

The content of the hole transporting material represented by the above general formula (2) is preferably in the range of 10 to 100 parts by weight based on 100 parts by weight of the binder resin of the charge transporting layer. And more preferably 20 to 70 parts by weight. When the content of the hole transport material is less than 10 parts by weight, the sensitivity of the obtained photoreceptor is deteriorated. Conversely, when the content of the hole transport material exceeds 100 parts by weight, the abrasion resistance of the obtained photoconductor may be reduced.

The content of the electron transporting material represented by the above general formula (1) is 20 to 80% by weight in the charge transporting material.
And particularly preferably 30 to 70% by weight. When the content of the electron transporting material in the charge transporting material is less than 20% by weight, the sensitivity of the obtained photoreceptor,
Poor repetition characteristics. On the other hand, when the content of the electron transport material exceeds 80% by weight, the sensitivity of the obtained photoreceptor deteriorates. Preparation of the photoreceptor When the above layers are formed by a coating method, the above-described examples of the charge generation material, the charge transport material, the binder resin and the like, together with a suitable solvent, a known method, for example, a roll mill,
Disperse and mix using a ball mill, attritor, paint shaker or ultrasonic disperser to adjust the coating solution,
This may be applied and dried by known means.

As the solvent for preparing the coating solution, 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, aromatic hydrocarbons such as benzene, toluene and xylene, halogenated hydrocarbons such as dichloromethane, dichloroethane, carbon tetrachloride and chlorobenzene, dimethyl ether, diethyl ether and tetrahydrofuran And ethers such as ethylene glycol dimethyl ether and diethylene glycol dimethyl ether; ketones such as acetone, methyl ethyl ketone and cyclohexanone; esters such as ethyl acetate and methyl acetate; dimethyl formaldehyde, dimethyl formamide, and dimethyl sulfoxide. These solvents can be used alone or in combination of two or more.

Further, in order to improve the dispersibility of the charge transporting material and the charge generating material and the smoothness of the surface of the photosensitive layer, a surfactant, a leveling agent and the like may be used. Hereinafter, the present invention will be described in detail with reference to Examples and Comparative Examples.

[0062]

【Example】

Synthesis Example 1 3,5-diisopropyl-3 ^, -tertbutyl-5 ^, -
Synthesis of phenyl-4,4 ^, -diphenoquinone 500 equipped with oxygen gas inlet pipe, waste gas outlet pipe and stirrer
In a milliliter separable flask, 7.8 g of 2,6-diisopropylphenol, 2-tertbutyl-6-
9.94 g of phenylphenol, 0.18 of cuprous chloride
g, 0.414 g of tetramethylethylenediamine, and 100 ml of methanol, and the reaction was completed with vigorous stirring while flowing pure oxygen gas through the gas phase of the flask. The precipitated crystals were separated by filtration, washed with water and dried. Then
Separation by column chromatography packed with silica gel yielded the target compound represented by the following general formula (c). The yield of the desired product was 4.9 g (yield 27%).

[0063]

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Synthesis Example 2 Synthesis of 3,5-diisopropyl-3 ^, -(α, α, γ, γ-tetramethylbutyl) -5 ^, -phenyl-4,4 ^, -diphenoquinone The reaction was conducted in the same manner as in Synthesis Example 1 except that 2,6-diisopropylphenol and 2- (α, α, γ, γ-tetramethylbutyl) -6-phenylphenol were used. I got things. The yield of the desired product was 6.4 g (yield 32
%)Met.

[0065]

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Synthesis Example 3 3,5-di (secondary butyl) -3 ^, -tertbutyl-5 ^,
Synthesis of -Phenyl-4,4 ^, -diphenoquinone Same as Synthesis Example 1 except that 2,6-di (secondary butyl) phenol and 2-tertbutyl-6-phenylphenol were used as disubstituted phenols as raw materials. To obtain the target compound represented by the following general formula (b).

[0067]

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Examples 1 to 9 and Comparative Examples 1 to 7 5 parts by weight of a charge generating material, 40 parts by weight of an electron transporting material, 40 parts by weight of a hole transporting material, 100 parts by weight of a polycarbonate resin as a binder resin, and A fixed amount of dichloromethane was mixed and dispersed by a ball mill to prepare a single-layer type photosensitive layer coating solution. The prepared solution was applied on an aluminum sheet with a wire bar, and dried with hot air at 100 ° C. for 60 minutes to obtain an electrophotographic photoreceptor having a single-layer type photosensitive layer having a thickness of 15 to 20 μm.

The charge generating material used is a compound represented by the following (I): I: X-type metal-free phthalocyanine (IP = 5.38)
eV) The hole transport material used is a compound number of the following formulas (A) to (E).

[0070]

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[0071]

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The used electron transporting material is represented by the above formulas (a) to (a).
This is specifically shown in Table 2 using the compound number of (d). The following tests were performed on the electrophotographic photosensitive members of each of the above Examples and Comparative Examples, and the characteristics were evaluated. Electrical characteristics Electrostatic copying tester (Kawaguchi Electric Co., Ltd., EPA-810
0), by applying an applied voltage of ± 7 KV to the surface of the sheet-shaped electrophotographic photosensitive member prepared in each of Examples and Comparative Examples to positively or negatively charge the surface, the initial surface potential V1
(V) was measured. Thereafter, a halogen lamp as an exposure light source was used to irradiate white halogen light for an exposure time of 6 seconds to measure the half-life exposure amount. That is, the initial surface potential V1
The time until (V) became 1/2 was determined, and the half-life exposure amount (μJ / cm ² ) was determined. Further, the surface potential at the time when 3 seconds had elapsed since the start of exposure was determined as the initial residual potential V2 (V).

Table 2 shows the above results. The electrophotographic photoreceptor obtained in each of the above Examples and Comparative Examples was repeated ,
After each was pasted on an aluminum cylinder using an adhesive tape, it was mounted on an electrostatic copying machine DC-1656 (manufactured by Mita Kogyo Co., Ltd.).

Next, copying is repeated 1000 times, and the subsequent surface potential V1 '(V) and post-exposure potential V2'
(V) was measured using a surface electrometer, and the difference between the initial surface potential and the initial residual potential was calculated using the following equation. (However, the measurement was performed with positive charge.)

[0075]

(Equation 1)

[0076]

[Table 2]

As is clear from Table 2, the electrophotographic photosensitive members of the present invention shown in Examples 1 to 9 are excellent in the post-exposure potential, half-exposure amount and repetition characteristics. It can be seen that the photographic characteristics show high performance.
On the other hand, the electrophotographic photosensitive members of Comparative Examples 1 to 7 had high potential after exposure, had poor sensitivity, and had extremely poor repetition characteristics.

[0078]

According to the present invention, the diphenoquinone derivative represented by the general formula (1) as an electron transport material and the compound represented by the general formula (2) as a hole transport material are selected. An organic photoreceptor having excellent electrophotographic properties can be provided.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-3-256050 (JP, A) JP-A-3-144573 (JP, A) JP-A 64-82046 (JP, A) JP-A 61- 134767 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G03G 5/00-5/16

Claims (1)

(57) [Claims] 1. An electron transporting material having the following general formula (1) on a conductive substrate: (Wherein, R1, R2, R3 and R4 represent a hydrogen atom, an alkyl group which may have a substituent, an alkoxy group, or an aryl group. However, two of R1, R2, R3 and R4 are the same. And the same group and the other two are
Different groups . And a diphenoquinone compound represented by the following general formula (2) as a hole transport material: (Wherein, R 5, R 6, R 7 and R 8 represent a hydrogen atom, an alkyl group or an alkoxy group, each of which may be substituted plurally, and n represents an integer of 1-2 ). An electrophotographic photosensitive member comprising a photosensitive layer containing: