JP2001265031A - Electrophotographic photoreceptor, process cartridge and electrophotographic device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrophotographic photoreceptor having high performance and a long service life at a low cost by utilizing a new electron transferring material excellent in electron transferring ability, compatibility with a resin, chemical stability, etc. SOLUTION: The electrophotographic photoreceptor has a layer containing an N,N'-heterosubstituted aromatic tetracarboxylic acid diimide compound of the formula RN(CO)2X(CO)2NR' (where X is a tetravalent group having an optionally substituted aromatic cyclic structure, R and R' are mutually different hydrocarbon groups or heteroatom-containing hydrocarbon groups and these are groups independent of imido groups and π-electron conjugation).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an electrophotographic photosensitive member utilizing a novel electron transport material, a process cartridge using the same, and an electrophotographic apparatus.

[0002]

2. Description of the Related Art In recent years, electrophotographic technology has played a central role in various image output fields such as copying machines, printers, and facsimile machines because of its advantages such as high speed and high printing quality. . As a constituent material of the electrophotographic photoreceptor, which is the heart of electrophotographic technology,
Inorganic photoconductive materials such as selenium, selenium-tellurium alloy and selenium-arsenic alloy have been widely used. However, research and development of organic photoreceptors (electrophotographic photoreceptors using organic photoconductive materials), which are superior in cost, mass productivity, safety, etc., to inorganic photoreceptors using these, have been actively conducted. At present, it has surpassed the inorganic photoreceptor.

[0003] In particular, the introduction of a function separation design in which the photocharge generation and charge transport, which are the elementary processes of photoconduction, are carried out by different materials, respectively, increases the degree of freedom of material selection and the diversity of organic materials. A remarkable improvement in performance has been achieved, and today, a thin film charge generation layer that performs the charge generation function and a thick charge transport layer that performs the charge transfer function, chargeability, and mechanical strength are laminated on the conductive support. Function-separated and laminated organic photoconductors are the mainstream of electrophotographic photoconductors.

By the way, organic charge transporting materials include:
Most hole transport materials such as triphenylamine derivatives and hydrazone derivatives are used, and electron transport materials having practical-level performance are rare. Due to this material limitation and the above-mentioned structure composed of the conductive support / charge generation layer / charge transport layer, the organic photoreceptor has an operation polarity restriction that it generally operates only with negative charge.

[0005] Regarding the operating polarity, there is a preferred polarity depending on the subsystem used and the total system. In order to utilize the organic photoreceptor more widely and more efficiently,
In addition to the negative charging type, development of a positive charging type and further a bipolar charging type photoconductor is desired.

For example, if an inexpensive wire-discharge type charger such as a scorotron is used as a charging subsystem, there is a problem that harmful gases such as ozone and nitrogen oxides are generated during discharge. It is known that the order of generation of this harmful gas is about an order of magnitude smaller in the case of positive charging than in the case of negative charging even with the same charger, so that it is not possible to install a filter or the like for removing harmful gas. In a small electrophotographic apparatus, a positively charged photoconductor is desired.

On the other hand, in order to meet the demand for high image quality, when using the current developer, it is desirable to perform reversal development using a negatively charged photosensitive member. At this time, it is necessary to take measures such as using a filter of activated carbon or the like to remove toxic gas, or using a contact charging type charger that generates a small amount of harmful gas.

When the transfer is performed electrostatically by employing the reversal development method, the charge polarity at the time of transfer is opposite to the charge polarity at the time of forming a latent image. In principle, the charging at the time of transfer is performed via a transfer target such as paper or a primary transfer film. Therefore, the photoreceptor is not directly charged. The photoreceptor is charged to a polarity opposite to that of the latent image when the photoreceptor is formed between the photoreceptor and the like. In this case, the photoreceptor that operates only with a single polarity cannot optically erase the reverse polarity charge during transfer, so that the history may appear in the next copy or print depending on the capability of the charger. May occur.
This problem is fundamentally solved by using a bipolar charging type photoreceptor having a hole transporting property and an electron transporting property.

On the other hand, the function-separated laminated organic photoreceptor has the following drawbacks due to its laminated structure.
There is a long-felt need to develop a photoreceptor that can overcome these disadvantages. A first drawback caused by the laminated structure is that two or more layers must be formed as compared with a single-layer photoreceptor, so that the productivity is reduced and the cost is increased. The second drawback caused by the lamination structure is that when using the dip coating method, which is a film forming method that is generally widely used and has high mass productivity, it is necessary to prevent the lower layer from being eroded during the coating of the upper layer. Therefore, the lower layer material is required to have resistance to the upper layer coating solvent, and there is a problem associated therewith. That is, generally, the lower charge generation layer is composed of a pigment as a charge generation material and a binder resin having a film forming property, and a material that is not affected by a coating solvent of the upper charge transport layer as the binder resin. Must choose. Generally, the charge transport material is relatively low in polarity, and a relatively low polarity solvent such as toluene, chlorobenzene, tetrahydrofuran, dioxane, or dichloromethane is used as the coating solvent. Highly polar thermoplastic resins such as an acetal-modified vinyl alcohol resin having low solubility in a solvent and a vinyl chloride-vinyl acetate-maleic anhydride copolymer resin are employed.

[0010] However, it is known that the charge transporting property is reduced in a high-polarity resin, and the high-polarity resin has a high hygroscopicity, which may cause a change in photoelectric characteristics due to environmental changes. Further, since these high-polarity thermoplastic resins are not completely insoluble, it is difficult to avoid a slight roughening at the time of application of the upper layer, and may cause photoelectric characteristics and eventually in-plane unevenness of an image. In particular, improvements are desired in applications to electrophotographic devices that require full-color, high-quality images.

As a method for avoiding these problems, it has been proposed to use a thermosetting resin as the binder resin of the charge generation layer. However, the curing reaction proceeds with time in a coating solution to increase the viscosity.
There are problems such as pot life that gelation occurs, uncured sites remain during film formation and adversely affect photoelectric characteristics, and the like, and the problem has not yet been solved. In addition, since the charge generation material such as a pigment cannot be completely insoluble in the solvent for coating the charge transport layer, contamination of the charge transport layer coating tank due to elution of the charge generation material progresses as the number of coatings increases. , Causing problems with pot life restrictions.

The third disadvantage caused by the laminated structure is as follows.
When coherent light such as a laser is used as an exposure light source, there is a problem that image defects of a stump pattern generally called interference fringes are generated due to specular reflection at an interface between the charge generation layer and the charge transport layer.

As a method for avoiding this problem, the surface of the support is roughened or a rough surface film is provided between the support and the photosensitive layer in order to make the interface uneven so that light is scattered. Measures have been taken. However, these measures themselves increase the cost themselves, and also require manufacturing difficulties in that a thin charge generation layer must be uniformly formed on a rough surface.

By the way, as a means for eliminating the problem caused by the above-mentioned laminated structure, a single-layered electrophotographic photosensitive member (single-layer type photosensitive member) has been known for a long time. However, the conventional single-layer type photoreceptor has not been designed to have a sufficient function separation, and none of the conventional photoreceptors has characteristics that can withstand practical use. That is, the conventional single-layer photoreceptor simply contains a charge generating material and a charge transporting material in an insulating resin. It was necessary to increase the concentration of the generated material, and as a result, there were problems such as a large dark decay and a large change in the photoelectric characteristics due to repeated use. Problem is suppressed).

To solve this problem, a single-layer type photoreceptor in which an insulating resin contains a charge generating material, a hole transporting material, and an electron transporting material has recently been proposed, and a remarkable improvement in performance has been achieved. (Journal of the Society of Electrophotography, Vol. 3
0, pp. 274-281, 1991). That is, by adding both a hole transporting material and an electron transporting material as a charge transporting material, not only one as in the conventional case, there is no restriction on the polarity of the transported charge, and charges are generated inside the photosensitive layer of the electrophotographic photosensitive member. However, since both charges are transported to the opposite electrode by the respective transport materials, the amount of the charge generating material added can be significantly reduced, and the above-mentioned problem has been solved.

However, although many hole transport materials having both high resin compatibility and high charge mobility are known, electron transport materials having both high resin compatibility and high charge mobility are rare. In order to put a function-separated single-layer type photoreceptor made of a charge generation material, a hole transport material, and an electron transport material into practical use, it is essential to develop an electron transport material having both high resin compatibility and high charge mobility.

In order to exhibit an electron transporting property, it is essential to be able to take a stable anion radical state.
Most electron transport materials have a π having an electron-withdrawing group.
It is a conjugated compound.

However, a π-conjugated compound having an electron-withdrawing group is a compound having a planar structure having a high polarity and necessarily having high crystallinity, and having a fate of poor compatibility with a resin. become. As a method of improving this problem, there are measures such as reducing the polarity of the whole molecule by introducing an electron-withdrawing group symmetrically, and reducing cohesion by introducing a bulky non-polar substituent. It has been found to be effective.

Furthermore, as for a method for introducing a bulky non-polar substituent, it has been reported that the effect is particularly remarkable by introducing a bulky non-polar substituent asymmetrically in a diphenoquinone-based electron transport material. ing. However, diphenoquinone-based electron transport materials are
There are problems such as low chemical stability and the necessity of using harmful oxidizing agents such as potassium permanganate for the synthesis.

[0020]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned conventional problems and achieve the following objects. That is, the present invention provides a high-performance and long-life electrophotographic photoreceptor at low cost by utilizing a novel electron transporting material having excellent electron transporting properties, compatibility with a resin, and chemical stability. The purpose is to do. Specifically, a first object of the present invention is to provide an electrophotographic photosensitive member that can be charged to a positive polarity or a bipolar polarity. A second object of the present invention is to provide a high-quality and highly durable process cartridge and an electrophotographic apparatus using the electrophotographic photoreceptor having the above excellent characteristics.

[0021]

Means for solving the above problems are as follows. That is, <1> an electrophotographic photoreceptor having a layer containing an N, N 'heterosubstituted aromatic tetracarboxylic diimide compound represented by the following general formula (1). RN (CO) ₂ X (CO) ₂ NR ′ ... General formula (1) In general formula (1), X represents a tetravalent group having a substituted or unsubstituted aromatic ring structure. R and R 'represent different hydrocarbon groups or heteroatom-containing hydrocarbon groups, and these groups are not based on imide groups and π-electron conjugation.

In the general formula (1), X is preferably a benzene structure or a naphthalene structure, and at least one of R and R 'preferably has a branched structure or a ring structure. The electrophotographic photoreceptor is simultaneously formed with an N, N ′ heterosubstituted aromatic tetracarboxylic diimide compound (electron transport material) represented by the general formula (1):
It preferably contains a hole transport material. Further, it is preferable that the electrophotographic photosensitive member has a function-separated single-layer structure.

<2> A process cartridge detachable from an electrophotographic apparatus, comprising the electrophotographic photosensitive member according to <1>. <3> An electrophotographic apparatus including the electrophotographic photosensitive member according to <1> or the process cartridge according to <2>. In the electrophotographic apparatus, when the electrophotographic photoreceptor is an electrophotographic photoreceptor having a function-separated single-layer configuration, the charging unit is a charging unit for negatively charging the electrophotographic photoreceptor, and the developing unit is It is preferable that the developing means be a reversal developing system.

[0024]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail. A: Overall Configuration of Photosensitive Layer of Electrophotographic Photoreceptor of the Present Invention The photosensitive layer of the electrophotographic photoreceptor of the present invention is shown in FIG.
To FIG. 3. Here, FIG.
3 are schematic cross-sectional views showing the cross section of the electrophotographic photoreceptor of the present invention.

In FIG. 1, on the surface of the conductive support 1,
The charge generation layer 2 is provided, and the charge transport layer 3 is provided thereon. In FIG. 2, on the surface of the conductive support 1,
The charge transport layer 3 is provided, and the charge generation layer 2 is provided thereon. In FIG. 3, on the surface of the conductive support 1,
A charge transport layer 3 is provided, in which fine particles 4 made of a charge generating material are dispersed. These electrophotographic photoreceptors can be further provided with an undercoat layer, an intermediate layer, a protective layer, and the like, if desired.

Among the constitutions of the photosensitive layers in the electrophotographic photosensitive member of the present invention, the function-separating single-layer constitution shown in FIG. 3 in which the charge transporting layer contains a charge generating material remarkably exerts the advantageous effects of the present invention. Demonstrate. That is, it has a manufacturing advantage such as low manufacturing cost and high productivity due to a single layer, and a special surface of the conductive support which is indispensable for avoiding the problem of interference fringes in the above-mentioned laminated photoreceptor. There is no need to process or provide an undercoat layer, and there is no problem due to the thin-film charge generation layer. In this regard, reduction in manufacturing cost and reduction in in-plane unevenness can be realized.

In addition, both holes and electrons generated in the charge generating material are separated and transported by the hole transporting material and the electron transporting material, respectively.
High charge separation efficiency (that is, charge generation efficiency) is achieved, and excellent repetition stability is realized. Furthermore, since it has an excellent ambipolar charge transporting ability, the amount of the charge generating material to be added is also required to be a minimum, the deterioration of the transport characteristics due to the charge generating material is suppressed, and the decrease in mechanical strength is also suppressed. It has an outstanding effect. In addition, since the charge generation material and both charge transport materials coexist and the photoexcited state is quickly deactivated by charge transfer, the photochemical properties of the electrophotographic photoreceptor by light exposure as seen with ordinary laminated photoreceptors There is also an advantage that significant deterioration is suppressed. And since it is a single-layer electrophotographic photoreceptor, it is easy to collect and recycle electrophotographic photoreceptor materials from used electrophotographic photoreceptors, to effectively use resources by recycling, reduce waste, Enables cost reduction.

B: Electrophotographic Photoreceptor of the Present Invention The electrophotographic photoreceptor of the present invention contains an N, N ′ heterosubstituted aromatic tetracarboxylic acid diimide compound represented by the following general formula (1), and if necessary, And a layer containing other components. RN (CO) ₂ X (CO) ₂ NR ′ ... General formula (1) In general formula (1), X represents a tetravalent group having a substituted or unsubstituted aromatic ring structure. R and R 'represent different hydrocarbon groups or heteroatom-containing hydrocarbon groups, and these groups are not based on imide groups and π-electron conjugation.

[Charge Transport Layer] -Charge Transport Layer in Single Function Separation Layer Structure- When the electrophotographic photosensitive member of the present invention is an electrophotographic photosensitive member having a single function layer structure as shown in FIG. The reason for containing the N, N 'heterosubstituted aromatic tetracarboxylic diimide compound represented by (1) is as follows.

The N, N ′ hetero-substituted aromatic tetracarboxylic diimide compound represented by the general formula (1) is a material having both excellent charge transferability and resin compatibility, which has not been available as an electron transport material. . Also, conventionally, many hole transport materials having high resin compatibility and charge transferability have been known. Therefore, by using these electron transporting material and hole transporting material together, a low concentration of the charge generating material is sufficient, and problems such as dark decay and fluctuation of photoelectric characteristics due to repeated use do not occur. It is possible to easily provide an electrophotographic photoreceptor having a single-layer structure with a useful function and a high practicality.

Therefore, when the electrophotographic photoreceptor of the present invention has a function-separated single-layer structure, the charge transport layer has the general formula (1)
It is preferable to contain an N, N 'heterosubstituted aromatic tetracarboxylic acid diimide compound (electron transporting material), a hole transporting material, and a charge generating material, and to contain an insulating resin or the like as necessary.

The N, N 'heterosubstituted aromatic tetracarboxylic acid diimide compound is not particularly limited as long as it has the structure represented by the general formula (1). For example, the compound represented by the general formula (1) In addition to low molecular weight compounds, high molecular weight compounds having a structure represented by the general formula (1) in a part or all of the repeating units may be mentioned.

In the general formula (1), R and R 'are required to be different from each other for the following reason. Conventionally, N, N'-substituted aromatic tetracarboxylic diimide compounds in which R and R 'are the same are described in, for example, JP-A-56-95241, JP-A-5-117274, JP-A-5-125043, Each publication of JP-A-5-297614, Phys. Stat. Sol. (B) Vol. 1
90, pp. 555-563, 1995, etc., and has long been known as a group of electron transporting compounds. However, when R and R 'are the same, the molecule has a symmetrical structure and high crystallinity, so that the solubility in a solvent, the compatibility with a resin, and the like are particularly low, and There were problems such as precipitation of crystals during production. Further, even if an electrophotographic photoreceptor can be produced by suppressing crystal precipitation, crystallization occurs due to repeated use, resulting in non-uniformity of photoelectric characteristics, and there is a problem that image unevenness occurs.

On the other hand, in the N, N ′ heterosubstituted aromatic tetracarboxylic diimide compound represented by the general formula (1) used in the electrophotographic photoreceptor of the present invention, the substitution introduced at the N, N ′ position Since the groups R and R 'are different from each other, they have an asymmetric molecular structure. For this reason, remarkably improved solubility and compatibility with the resin are achieved as compared with the conventional N, N′-substituted aromatic tetracarboxylic acid diimide compound having a symmetric structure, and the above-mentioned problems do not occur. . As a result, a long-life electrophotographic photosensitive member can be easily manufactured at low cost.

In the general formula (1), R and R 'need to be groups not depending on imide groups and π-electron conjugation for the following reasons. In recent years, as an electron transporting material, an N, N ′ heterosubstituted aromatic tetracarboxylic diimide compound represented by the following structural formula (1) has been reported (Jpn. J. Appl. Phys. Vol. 3).
5, pp. 5384-5388, 1996).

[0036]

Embedded image

However, since this compound is in a π-electron conjugated system in which an electron-donating triphenylamine structure and an electron-withdrawing imide structure are directly bonded, charge transfer absorption (visible to near infrared) is obtained. (Charge transfer interaction). Further, it is known that such charge transfer interaction generally lowers the charge transporting property, and there is a concern that the charge transporting property may also be lowered.

On the other hand, in the N, N 'heterosubstituted aromatic tetracarboxylic acid diimide compound of the present invention represented by the general formula (1), R and R' are groups not depending on imide groups and π-electron conjugation. Therefore, the above problem does not occur.

In the general formula (1), the carbon number of R and R 'is preferably 1 to 20, more preferably 2 to 10, and further preferably at least one of the carbon atoms is 3 or more. When the number of carbon atoms exceeds 20, the proportion of electron transport active sites in the molecule is reduced,
While the electron transport property may be insufficient, if the carbon number is small, sufficient solubility and compatibility may not be exhibited.

In the general formula (1), examples of the hydrocarbon group represented by R and R ′ (including a hydrocarbon group containing a hetero atom) include an alkyl group, an arylalkyl group, an alkoxyalkyl group, an aryloxyalkyl Group, a halogenated alkyl group, etc., and particularly, an alkyl group is preferable in terms of electron transportability, and further, in view of low crystallinity, an alkyl group having at least one of a branched structure or a ring structure is preferred. More preferred. When the hydrocarbon group is substituted, the substituent is preferably an alkyl group, an alkoxy group, an aryl group, a halogen atom, or the like. Table 1 shows specific examples of preferable combinations of R and R '.
Shown in

[0041]

[Table 1]

In the general formula (1), X has the following structure, for example. Among these, a benzene structure of Y1 and a naphthalene structure of Y2 are particularly preferable in terms of electron transport ability and electron injection property from a charge generation material. When X is substituted,
As the substituent, an alkyl group, an alkoxy group, an aryl group, a halogen atom and the like are preferable.

[0043]

Embedded image

In general, the method for synthesizing the aromatic tetracarboxylic diimide compound is not particularly limited, and any known synthesis method can be used. However, from the viewpoint of simplicity, the corresponding aromatic tetracarboxylic acid diimide compound is synthesized. A synthesis method in which an anhydride and an amino compound are dehydrated and condensed is preferable. In order to obtain the N, N ′ heterosubstituted aromatic tetracarboxylic diimide compound represented by the general formula (1) used in the present invention, first, the corresponding aromatic tetracarboxylic dianhydride and RNH ₂ are combined. It reacted, followed by a method of reacting R'NH _2,
A method of simultaneously reacting an aromatic tetracarboxylic dianhydride with RNH ₂ and R′NH ₂ to separate an RR form and an R′R ′ form which are by-produced from a target RR ′ form can be used.

N, N 'having a polymerizable group at both ends
By synthesizing the heterosubstituted aromatic tetracarboxylic diimide compound in advance and homopolymerizing or copolymerizing it, a polymer compound having an N, N ′ heterosubstituted aromatic tetracarboxylic diimide structure in a repeating unit can be obtained. it can. Furthermore, a polymer compound having an N, N ′ heterosubstituted aromatic tetracarboxylic diimide structure as a repeating unit is obtained by polycondensing an aromatic tetracarboxylic acid and a diamine having an asymmetric structure via a polyamic acid. Obtainable. The imide compound is generally very stable, and the N, N ′ heterosubstituted aromatic tetracarboxylic diimide compound represented by the general formula (1) also has very high stability.

The hole transporting material is not particularly limited as long as it has a hole transporting property, and is a substituted or unsubstituted triarylamine structure in terms of hole transporting ability, chemical stability, amorphousness and the like. (Low molecular weight compounds, high molecular weight compounds) are preferred. Compounds having a triarylamine structure include triphenylamine,
Tetraphenylphenylenediamine, tetraphenylbenzidine, bis (diphenylamino) terphenyl, etc.
And a polymer compound containing these in a repeating structure. When the compound having a triarylamine structure has a substituent, examples of the substituent include an alkyl group, an aryl group, a halogen atom, and an alkoxy group.
Among these compounds having a triarylamine structure, as described above, in an electrophotographic photoreceptor having a function-separated single-layer structure, when used as a hole transport material, there is no need to use a resin component separately. It is preferable that the polymer compound is a polymer compound, and in particular, a polymer compound having a triarylamine structure represented by the following general formula (2) in the main chain in terms of mechanical strength, chemical stability, hole transportability, and the like. preferable.

[0047]

Embedded image In the general formula (2), Ar ¹ and Ar ² each independently represent a substituted or unsubstituted aryl group. X
¹ is a substituted or unsubstituted 2 having an aromatic ring structure
Represents a monovalent hydrocarbon group or a heteroatom-containing hydrocarbon group.
X ² and X ³ each independently represent a substituted or unsubstituted arylene group. L represents a divalent hydrocarbon group or a hetero atom-containing hydrocarbon group which may have a branched or ring structure. m is either 0 or 1.

In the general formula (2), examples of the aryl group represented by Ar ¹ and Ar ² include a phenyl group, a naphthyl group and a pyrenyl group. When the aryl group represented by Ar ¹ and Ar ² has a substituent, examples of the substituent include a methyl group, a methoxy group, a phenyl group, and a halogen atom.

In the general formula (2), examples of the hydrocarbon group represented by X ¹ include a phenylene group, a biphenylene group, a terphenylene group, a methylenebisphenyl group, a cyclohexylidenebisphenyl group and an oxybisphenyl group. No. When the hydrocarbon group represented by X ¹ has a substituent, examples of the substituent include a methyl group, a methoxy group, and a halogen atom. X ¹ is preferably a 3-methyl-m-phenylene group, a 3,3′-dimethyl-1,1′-biphenylene group or a terphenylene group in view of hole transportability, chemical stability and the like. Are preferred. In the general formula (2), examples of the arylene group represented by X ² and X ³ include a phenylene group. When the arylene group represented by X ² or X ³ has a substituent, examples of the substituent include a methyl group, a methoxy group, a phenyl group, and a halogen atom.

In the general formula (2), L is preferably a hydrocarbon group having 1 to 25 carbon atoms or a heteroatom-containing hydrocarbon group. Particularly, in view of mechanical strength and flexibility, an ester bond, A hetero atom-containing hydrocarbon group having an ether bond or a carbonate bond in the main chain is more preferable. Specific examples of the hole transporting polymer compound represented by the general formula (2) include JP-A-5-249706, JP-A-8-253568, JP-A-9-59361, and JP-A-10-182760. And the like.

In an electrophotographic photoreceptor having a function-separated single-layer structure, an N, N 'heterosubstituted aromatic tetracarboxylic diimide compound represented by the general formula (1) (electron transport material)
And the content of the hole transport material, respectively,
It is preferably from 15 to 85% by weight, more preferably from 20 to 75% by weight. If the content is less than the numerical range,
On the other hand, the charge transportability may be insufficient, and when both (electron and hole) transport materials are low molecular compounds, the mechanical strength may be insufficient if the value exceeds the above range.

The compounding ratio (weight ratio) of the N, N ′ heterosubstituted aromatic tetracarboxylic diimide compound (electron transporting material) represented by the general formula (1) and the hole transporting material is determined by the required electron transporting property. Although it cannot be said unconditionally because it is set by the hole transporting property and the transporting ability of each transporting material, generally, the weight ratio (N, N ′ heterosubstituted aromatic tetracarboxylic diimide compound (electron transporting material) ) / Hole transport material) = 2/8 to 8/2, more preferably 3/7 to 7/3.

The charge generating material is not particularly limited as long as it has a charge generating ability. For example, amorphous selenium, hexagonal selenium, selenium-tellurium alloy, selenium-arsenic alloy, other selenium compounds and selenium Inorganic photoconductive materials such as alloys, zinc oxide, titanium oxide, a-silicon, a-silicon carbide; phthalocyanine, squarium, anthantrone, perylene, azo,
Organic pigments and dyes such as polycyclic quinones, pyrenes, pyrrolopyrroles, pyrylium salts, and thiapyrylium salts are exemplified. These charge generating materials may be used alone or in combination of two or more.

Among these charge generation materials, organic pigments are preferable in terms of safety, fastness and the like. In particular, phthalocyanine pigments are widely used as light sources in digital electrophotographic apparatuses. Since it has excellent photosensitivity at 600 to 850 nm, which is the transmission wavelength of a laser diode, it is particularly preferable as the charge generation material in the present invention.

As the phthalocyanine pigment, metal-free phthalocyanines, metal phthalocyanines, and derivatives thereof can be used. As the central metal of the metal phthalocyanines, Cu, Ni, Zn, Co, Fe, V, Si,
Al, Sn, Ge, Ti, In, Ga, Mg, Pb, L
i and the like, and oxides, hydroxides, halides, alkylated compounds and alkoxylated derivatives of these central metals are also effective. Specifically, titanyl phthalocyanine, chlorogallium phthalocyanine, hydroxygallium phthalocyanine, vanadyl phthalocyanine, chloroindium phthalocyanine, dichlorotin phthalocyanine,
And dimethoxysilicon phthalocyanine. Also,
A substituted phthalocyanine having an arbitrary substituent introduced into a phthalocyanine ring is also included. Further, azaphthalocyanines in which an arbitrary carbon atom in the phthalocyanine ring is substituted with a nitrogen atom are also effective.

As the form of these phthalocyanine pigments, amorphous or all crystalline forms can be used as long as they have a charge generating ability. Among these phthalocyanine pigments, metal-free phthalocyanine, titanyl phthalocyanine, chlorogallium phthalocyanine,
Hydroxygallium phthalocyanine and dichlorotin phthalocyanine have particularly excellent photosensitivity and are particularly preferred as the charge generating material used in the present invention.

Further, azo pigments, polycyclic quinone pigments and perylene pigments are also preferred as charge generation materials because of their excellent charge generation efficiency. Since the beam diameter of the laser beam can be reduced as the transmission wavelength becomes shorter, studies are being made on shortening the wavelength of the exposure laser with the aim of further improving image quality.However, these pigments are visible from the ultraviolet region. Since it has high photosensitivity in the region, it is particularly suitable as a charge generation material for a short wavelength laser.

In the electrophotographic photosensitive member having the function-separated single-layer structure, the content of the charge generating material is 0.05
-30% by weight is preferred, 0.1-10% by weight is more preferred, and 0.3-5% by weight is even more preferred. When the content is less than the above numerical range, the absorbance of the photosensitive layer is insufficient, the photosensitivity is insufficient, or a support that uses coherent light such as a laser as an exposure light source and has not been subjected to a scattering treatment. If used, interference fringe problems may occur. On the other hand, when the content exceeds the numerical range,
Detrimental effects such as an increase in dark charge, a decrease in repetition stability, and a decrease in mechanical strength may be significant.

When a low-molecular compound is used as the charge transporting material (which may be any of an electron transporting material and a hole transporting material), an insulating material may be used to improve film-forming properties and mechanical strength. It is necessary to use a conductive resin in combination. As the insulating resin, a known resin such as a carbonate resin, an ester resin, an acrylic resin, a styrene resin, and a cyclic olefin resin is used. Further, a hole transporting material can be contained in the charge transporting layer, and a hole transporting resin may be used instead of the insulating resin. When the insulating resin is used, its content is preferably 15 to 70% by weight in terms of mechanical strength.
Is preferable, and 30 to 60% by weight is more preferable. on the other hand,
When a polymer compound is used as the charge transport material, the insulating resin does not need to be used, and the content of the charge transport material (electron transport material and hole transport material) can be relatively increased. It is advantageous in the point.

The method of forming the charge transport layer is not particularly limited, but is preferably a dip coating method, a blade coating method, a wire bar coating method, a spray coating method, in view of cost, simplicity of equipment, mass productivity, and the like. A wet coating method such as a bead coating method, an air knife coating method, a curtain coating method, and a ring coating method is preferably exemplified.

When an insoluble substance such as a pigment is used as the charge generating material, a uniform and stable coating solution can be obtained by a ball mill method, a paint shake method, an attritor method, a sand mill method, an ultrasonic method or the like. It is preferable to prepare a coating solution by treating with a pulverization / dispersion method.

Solvents used for preparing the coating solution include toluene, xylene, chlorobenzene, dichlorobenzene,
Aromatic solvents such as cresol; cyclic ether solvents such as tetrahydrofuran and dioxane; halogen solvents such as dichloromethane and dichloroethane; ketone solvents such as methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone; ester solvents such as butyl acetate and ethyl acetate. And alcohol solvents such as cyclohexanol and butanol, and amide solvents such as dimethylformamide and dimethylacetamide. These solvents may be used alone or in combination of two or more.

The amount of the solvent in the coating solution cannot be specified unconditionally, but it is desirable that the total solid component in the coating solution be in the range of 5 to 50% by weight depending on the coating suitability.

The thickness of the charge transport layer is 5 to 10
0 μm is preferable, 10 to 50 μm is more preferable, and 1
5-35 μm is more preferred.

-Charge transport layer in case of function-separated laminated structure- In the case where the electrophotographic photosensitive member of the present invention is an electrophotographic photosensitive member having a function-separated laminated structure as shown in FIG. 1 or FIG. The reason for containing the N, N 'heterosubstituted aromatic tetracarboxylic diimide compound represented by the formula (1) is as follows.

The N, N′-heterosubstituted aromatic tetracarboxylic diimide compound represented by the general formula (1) provides an electron transport layer having sufficient electron transport properties and stability. Therefore, by including the N, N 'heterosubstituted aromatic tetracarboxylic diimide compound represented by the general formula (1) in the charge transporting layer, an inexpensive corotron-type charger can be easily used in a positive electrode having an extremely small ozone generation amount. An electrophotographic photoreceptor having a function-separated laminated structure that can be used for charging can be obtained.

In the case where the electrophotographic photoreceptor of the present invention is the electrophotographic photoreceptor having the function-separated laminated structure, similarly to the electrophotographic photoreceptor having the function-separated single-layer structure, holes are formed in the charge transport layer. It is preferable that a transport material is contained and other components are contained as necessary. The N, N ′ heterosubstituted aromatic tetracarboxylic acid diimide compound represented by the general formula (1) and the hole transporting material are the same as those already described in the section of “Charge transporting layer in function-separated single layer configuration”. Can be suitably used.

The charge transport layer may be formed by dissolving the N, N ′ heterosubstituted aromatic tetracarboxylic diimide compound represented by the general formula (1) in a suitable insulating resin, or , N, represented by the general formula (1)
When the N ′ heterosubstituted aromatic tetracarboxylic diimide compound is a polymer compound, it may be formed alone without using an insulating resin. Preferred examples of the insulating resin include the insulating resins described in the section “Charge transport layer in function-separated single-layer structure”.

When the charge transport layer contains the insulating resin, the compounding ratio of the N, N ′ heterosubstituted aromatic tetracarboxylic diimide compound represented by the general formula (1) to the insulating resin ( (Weight ratio), N / N ′ heterosubstituted aromatic tetracarboxylic acid diimide compound / insulating resin represented by the general formula (1) = 7/3 to 2/8, preferably 5/5
/ 5 to 3/7 are more preferred. When the compounding ratio of the N, N ′ hetero-substituted aromatic tetracarboxylic diimide compound represented by the general formula (1) to the insulating resin exceeds the above numerical range, the strength of the charge transport layer may be significantly reduced. On the other hand, when the value is less than the above numerical range, troubles such as a decrease in photosensitivity and an increase in residual potential may be significant. Generally, the thickness of the charge transport layer is suitably about 5 to 50 μm, and preferably 10 to 35 μm.

The charge transport layer may be formed by a conventional wet method such as a blade coating method, a wire bar coating method, a spray coating method, a dip coating method, a bead coating method, an air knife coating method, a curtain coating method, and a ring coating method. An application method and the like can be mentioned.

[Charge Generating Layer] When the electrophotographic photosensitive member of the present invention has a function-separated laminated structure as shown in FIG. 1 or FIG. 2, the electrophotographic photosensitive member requires a charge generating layer. The charge generation layer contains a charge generation material and, if necessary, other components such as a binder resin. Suitable examples of the charge generation material include the charge generation materials already described in the section of “Charge transport layer in function-separated single-layer structure”.

The charge generation layer may be formed by a dry method in which the charge generation material is directly formed into a film by a vacuum evaporation method or the like, or a coating solution in which the charge generation material and a binder resin are dispersed and dissolved in an appropriate solvent. For example, a wet coating method of coating and drying the same can be used. Among them, the wet coating method is preferable in terms of cost, simplicity of equipment, mass productivity, etc., for example, dip coating method, blade coating method, wire bar cloth method,
Spray coating method, bead coating method, air knife coating method,
Suitable examples include a wet coating method such as a curtain coating method and a ring coating method. The thickness of the charge generation layer is usually 0.05 to 5 μm, and preferably 0.1 to 2.0 μm.
m is preferred.

When a binder resin is used for forming the charge generation layer, the kind of the binder resin is not particularly limited. For example, vinyl butyral resin, vinyl formal resin, partially modified vinyl acetal resin, carbonate resin, ester resin, Examples include acrylic resin, vinyl chloride resin, styrene resin, vinyl acetate resin, vinyl acetate resin, silicone resin, phenol resin, and vinyl carbazole resin. These binder resins may be block, random or alternating copolymers. These binder resins may be used alone or in combination of two or more.

When a binder resin is used for forming the charge generation layer, the mixing ratio (weight ratio) of the charge generation material to the binder resin is preferably 10/1 to 1/10, and more preferably 5/1.
１／1/1 is more preferable. If the compounding ratio of the charge generation material to the binder resin exceeds the above range, dark decay increases, and when a layer is formed by a wet coating method, it may be difficult to obtain a uniform film. On the other hand, when the value is less than the above numerical range, troubles such as a decrease in photosensitivity and an increase in residual potential may be significant. Further, the charge generation layer has a general formula (1)
By containing the N, N 'heterosubstituted aromatic tetracarboxylic acid diimide compound represented by the formula (1), favorable effects such as improvement in charge generation efficiency can be obtained.

[Conductive Support] The material of the conductive support used in the electrophotographic photoreceptor of the present invention is not particularly limited, and may be any material that can be used as a conductive support used in the art for an electrophotographic photoreceptor. Can be appropriately selected from the following types. Further, the conductive support may be transparent or opaque.

Examples of the material of the conductive support include metals such as aluminum, nickel, and stainless steel; aluminum, titanium, nickel, chromium, stainless steel, gold, platinum, zirconium, vanadium, tin oxide, and indium oxide. , Glass, ceramics and the like provided with a thin film of ITO, etc .; paper, plastic, glass and ceramics coated or impregnated with a conductivity-imparting agent. Examples of the shape of these conductive supports include appropriate shapes such as a drum shape, a sheet shape, a plate shape, and a belt shape. Various treatments can be applied to the surface of the conductive support as needed. Examples include electrolytic oxidation treatment; chemical treatment; mechanical surface roughening treatment such as graining, rough cutting, and honing; and mechanical mirroring treatment such as cutting and polishing.

[Other Configurations in Electrophotographic Photoreceptor of the Present Invention] -Undercoat Layer- In the present invention, the purpose of preventing electric charge from leaking from the conductive support to the photosensitive layer and / or to provide a photosensitive layer. An undercoat layer may be provided between the conductive support and the photosensitive layer for the purpose of integrally bonding and holding the conductive support.

The material of the undercoat layer is not particularly limited and can be appropriately selected from known materials. Examples thereof include ethylene resin, acrylic resin, methacrylic resin, amide resin, vinyl chloride resin, vinyl acetate resin, and phenol. Resin, urethane resin, imide resin, vinylidene chloride resin,
Vinyl acetal resin, vinyl alcohol resin, water-soluble ester resin, alcohol-soluble nylon resin, nitrocellulose resin, acrylic resin, acrylamide resin and other resins and copolymers thereof, or zirconium alkoxide compounds, titanium alkoxide compounds,
A curable metal organic compound such as a silane coupling agent may be used. These may be used alone or in combination of two or more. Further, a material capable of transporting only charges having the same polarity as the charged polarity is also effective as the undercoat layer.

The method for forming the undercoat layer may be a coating method using a blade coating method, a wire bar coating method, a spray coating method, a dip coating method, a bead coating method, an air knife coating method, a curtain coating method, a ring coating method, or the like. An ordinary wet coating method in which the composition is applied and dried to form a coating can be used. Such a coating solution can be prepared by dissolving and dispersing the components of the undercoat layer in an appropriate solvent. The thickness of the undercoat layer is preferably 0.005 to 10 μm,
01 to 5 μm is more preferable.

-Surface Charge Transporting Layer- When the electrophotographic photoreceptor of the present invention has a function-separated single-layer structure shown in FIG. , A monopolar or bipolar surface charge transport layer can be provided. The unipolar surface charge transport layer is not particularly limited, and the configuration of a conventionally known charge transport layer can be applied as it is. As the amphoteric surface charge transport layer, the amphoteric charge transport layer in the present invention is particularly preferably exemplified. As a method of forming these surface charge transport layers, dip coating, blade coating, wire bar coating, spray coating,
Bead coating method, air knife coating method, curtain coating method,
An ordinary wet coating method in which a coating liquid is applied by a ring coating method or the like and dried to form a coating liquid can be used. Such a coating solution can be prepared by dissolving and dispersing each component of the surface charge transport layer in an appropriate solvent. The thickness of the surface charge transport layer is preferably from 0.5 to 10 μm.

-Protective Layer- In the electrophotographic photoreceptor of the present invention, ozone and oxidizing gas generated from the charging member, and chemical stress such as ultraviolet light, or developer, paper, cleaning member, etc. With the aim of protecting the photosensitive layer from mechanical stress caused by contact of the photosensitive layer and improving the substantial life of the photosensitive layer,
If desired, a protective layer can be provided on the photosensitive layer.

The protective layer is formed by including a conductive material in a suitable binder resin. As the conductive material,
Metallocene compounds such as dimethylferrocene, antimony oxide, tin oxide, titanium oxide, indium oxide, ITO
And the like, but are not limited thereto.

Examples of the binder resin that can be used for forming the protective layer include known amide resins, urethane resins, ester resins, carbonate resins, styrene resins, acrylamide resins, silicone resins, melamine resins, phenol resins, and epoxy resins. Resins. Also,
A charge transport material may be added to the protective layer for the purpose of reducing the residual potential and the like.

The protective layer may be formed by dip coating, blade coating, wire bar coating, spray coating, bead coating, air knife coating, curtain coating, ring coating, or the like. A wet coating method in which the composition is applied and dried to form a coating is used. Such a coating solution can be prepared by dissolving and dispersing the components of the protective layer in an appropriate solvent. The thickness of the protective layer is 0.1
To 20 μm is preferable, and 0.5 to 10 μm is more preferable. The protective layer also functions as a charge injection layer when used in combination with a charge injection type charger, so that stable charging by the charge injection type charger becomes possible.

When a protective layer is provided, if desired,
Between the photosensitive layer and the protective layer, a blocking layer for preventing leakage of electric charge from the protective layer to the photosensitive layer can be provided.
As the blocking layer, a known layer can be used as in the case of the protective layer.

The electrophotographic photoreceptor of the present invention described above is
An antioxidant, a light stabilizer, a heat stabilizer, and the like can be appropriately added to an arbitrary layer, if desired, for the purpose of preventing deterioration of the photoreceptor due to ozone, an oxidizing gas, light, or heat.

Examples of the antioxidant include known ones, such as hindered phenol, hindered amine, paraphenylenediamine, hydroquinone, spirochroman, spiroidanone and derivatives thereof,
Organic sulfur compounds, organic phosphorus compounds and the like can be mentioned. Examples of the light stabilizer include known ones, for example, benzophenone, benzotriazole, dithiocarbamate, derivatives such as tetramethylpiperidine, and electron-withdrawing compounds that can deactivate the photoexcited state by energy transfer or charge transfer. Or an electron donating compound. As the heat stabilizer, a known heat stabilizer may be used. In addition, the surface layer (protective layer,
Fine particles such as a fluororesin and silica may be dispersed in the photosensitive layer or the surface charge transporting layer.

As described above, the electrophotographic photoreceptor of the present invention utilizes a novel electron transporting material having excellent electron transporting properties, compatibility with resins, chemical stability, and the like. It is a long-life electrophotographic photosensitive member, can be charged to a positive polarity or a bipolar polarity, and by using this, it is possible to provide a process cartridge and an electrophotographic apparatus having high image quality and high durability. Also,
N, N ′ represented by the general formula (1) used in the present invention
Heterosubstituted aromatic tetracarboxylic diimide compounds have high electron transportability, high amorphousness, and high chemical stability, and therefore, in addition to the electrophotographic photoreceptor provided in the present invention, organic electroluminescent elements, organic It can also be used for various organic electronic devices such as photorefractive elements, organic light sensors, and organic solar cells.

C: Process Cartridge of the Present Invention The process cartridge is intended to replace some consumable parts of the electrophotographic apparatus in a timely manner so that some of the components of the electrophotographic apparatus are incorporated into the cartridge so that the replacement operation can be easily performed. It was done. The process cartridge is traded in a state of being mounted in the electrophotographic apparatus, and is also traded alone as a replacement part or a repair part.

The components that can be incorporated in the process cartridge generally include a charging unit, a developing unit, an exposing unit, a cleaning unit, and the like, and these can be arbitrarily combined according to the purpose.

The process cartridge of the present invention has the electrophotographic photosensitive member of the present invention. The components other than the electrophotographic photosensitive member that can be incorporated in the process cartridge of the present invention are not particularly limited, and conventionally known means as described above can be employed without any problem. Since the process cartridge of the present invention described above incorporates the electrophotographic photoreceptor of the present invention, a high-quality image can be formed and the durability is high.

D: Electrophotographic Device of the Present Invention The electrophotographic device on which the electrophotographic photosensitive member of the present invention is mounted may be any device as long as it uses an electrophotographic method. An electrophotographic apparatus that performs exposure based on a signal is preferable. An electrophotographic apparatus that performs exposure based on a digitally processed image signal is an electrophotography that performs exposure in accordance with a multilevel signal by performing binarization or pulse width modulation or intensity modulation using a light source such as a laser or LED. The apparatus is, for example, an LED printer, a laser printer, a laser exposure digital copier, or the like. As the electrophotographic apparatus of the present invention,
In the case of an electrophotographic photosensitive member having a function-separated single-layer structure, a device provided with a charger for negatively charging the surface of the electrophotographic photosensitive member and a developing device of a reversal developing system is particularly preferable in terms of image quality and the like.

FIG. 4 schematically shows an example of the electrophotographic apparatus of the present invention. The electrophotographic apparatus shown in FIG. 4 is a laser printer, and a cylindrical photosensitive drum 1 which is an electrophotographic photosensitive member.
Around the LED 1, a charge removing LED 12 serving as a charge removing light source, a charging scorotron 13 serving as a charging unit, an exposure laser optical system 14 serving as an image exposing unit, a developing unit 15, a transfer contact charging roll 16, and a cleaning unit. Certain cleaning blades 17 are arranged in this order. The exposure laser optical system 14 includes, for example, an exposure laser diode having a transmission wavelength of 780 nm, and emits light based on digitally processed image signals. Laser light emitted 1
4a is configured to expose the surface of the electrophotographic photosensitive member while being scanned by a polygon mirror, a plurality of lenses, and a mirror. Reference numeral 18 denotes a sheet.

In the electrophotographic apparatus of the present invention, the photoconductor drum 11 is the electrophotographic photoconductor of the present invention. Of course,
The electrophotographic photoreceptor may include a photoreceptor drum 11 and any combination of other components, and the electrophotographic photoreceptor may include a process cartridge that is the electrophotographic photoreceptor of the present invention.

As described above, the electrophotographic apparatus of the present invention has been described with reference to the drawings. However, the present invention is not limited to such a configuration, and the components other than the electrophotographic photosensitive member are not particularly limited. Conventionally known ones can be adopted without any problem.

[0096]

The present invention will be specifically described below with reference to examples. However, the present invention is not limited to the following Examples, and those skilled in the art can make modifications to the following Examples based on known knowledge of chemical technology and electrophotographic technology.

[Examples and Comparative Examples of the First Present Invention] <Synthesis Example 1> An equimolar mixture of 1,4,5,8-naphthalenetetracarboxylic dianhydride and hexylamine was added to 4
-Refluxed in picoline with stirring for 5 hours. After cooling, the reaction mixture was poured into dilute hydrochloric acid, the solid was collected by filtration, and dried under reduced pressure under heating to obtain a solid. The obtained solid is washed with methylene chloride to remove by-produced N, N'-dihexylnaphthalenetetracarboxylic acid diimide, and then extracted with boiling acetone to give unreacted naphthalenetetracarboxylic acid diimide as a residue. The anhydride is separated by filtration, acetone is distilled off from the acetone solution, and dried to obtain the following structural formula (2)
Was obtained.

[0098]

Embedded image

A mixture of the obtained monoimide compound and a 5-fold molar amount of cyclohexylamine was refluxed in 4-picoline with stirring for 5 hours. After cooling, the reaction mixture was poured into dilute hydrochloric acid, the solid was collected by filtration, and dried under reduced pressure under heating to obtain a solid. The obtained solid was purified by column chromatography using silica gel / toluene, followed by recrystallization from acetonitrile to obtain the desired N-hexyl-N′-cyclohexyl-1,4,5,8. -Naphthalenetetracarboxylic diimide (an N, N 'heterosubstituted aromatic tetracarboxylic diimide compound represented by the general formula (1)) was obtained.

Synthesis Example 2 A mixture of 1 mol of 1,2,4,5-benzenetetracarboxylic dianhydride, 5 mol of 4-chlorobutylamine and 5 mol of (1,2-dimethylpropyl) amine was Reflux in 4-picoline with stirring for 5 hours. After cooling, the mixture was poured into diluted hydrochloric acid, the solid substance was collected by filtration, and this was dried under reduced pressure under heating to obtain a solid substance. The obtained solid was purified by column chromatography using silica gel / chloroform, followed by recrystallization from acetonitrile to obtain the desired N- (4-chlorobutyl) -N ′-(1,2- Dimethylpropyl) -1,2,2
4,5-benzenetetracarboxylic diimide (an N, N ′ heterosubstituted aromatic tetracarboxylic diimide compound represented by the general formula (1)) was obtained.

Example 1 Preparation of Electrophotographic Photoreceptor At least a Bragg angle (2θ ± 0.2 °) in an X-ray diffraction spectrum using CuKα as 7.4 °
Chlorogallium phthalocyanine microcrystal 3 having strong diffraction peaks at 16.6 °, 25.5 °, and 28.3 °
Parts by weight, 80 parts by weight of cyclohexanone, and 1,2-
After mixing 320 parts by weight of dichloroethane and dispersing for 5 hours by a paint shake method with SUS beads,
Electron transporting N-hexyl- obtained in Synthesis Example 1
30 parts by weight of N'-cyclohexyl-1,4,5,8-naphthalenetetracarboxylic acid diimide, 20 parts by weight of a hole-transporting low-molecular compound represented by the following structural formula (3),
Bisphenol Z type polycarbonate (PC-Z,
47 parts by weight (manufactured by Mitsubishi Gas Chemical Co., Ltd.) and further subjected to dissolution dispersion treatment by a ball mill method for 2 hours to prepare a coating liquid for a function-separated single-layer type photoreceptor.

[0102]

Embedded image

The obtained coating solution for functionally separated single-layer type photoreceptor was applied by dip coating to the surface of a 30 mm-diameter aluminum drum (conductive support) whose surface was mirror-finished.
It was dried by heating at 15 ° C. for 60 minutes to produce an electrophotographic photoreceptor having a function-separated single layer structure shown in FIG. Incidentally, the thickness of the photosensitive layer was 15 μm.

-Evaluation (Evaluation of Image Quality and Durability)-The obtained electrophotographic photosensitive member was mounted on a commercially available laser printer (Laser Press 4150, manufactured by Fuji Xerox Co., Ltd.) and subjected to a normal temperature and normal humidity environment (20 ° C., 50% RH). ) Below, printing was performed continuously for 5000 sheets in the A4 horizontal direction, and a print test was performed. The image quality and the durability were evaluated by visually observing the first and the print samples after continuous printing of 5000 sheets. Table 2 shows the results. The laser printer used for evaluation has the configuration shown in FIG. 4 and includes a charger for negative charging and a developing device of a reversal developing system.

Example 2 In Example 1, N-hexyl-N′-cyclohexyl-1,4,5,8-naphthalenetetracarboxylic diimide was replaced with N-hexyl-N′-cyclohexyl-1,4,5,8-naphthalenetetracarboxylic diimide. -(4-chlorobutyl) -N'-
An electrophotographic photoreceptor was prepared in the same manner as in Example 1 except that (1,2-dimethylpropyl) -1,2,4,5-benzenetetracarboxylic diimide was used. An evaluation was performed. Table 2 shows the results.

Example 3 In Example 1, the surface of the aluminum drum (conductive support) was roughened by wet honing treatment with alumina particles (arithmetic average roughness: Ra = 0.20 μm). An electrophotographic photoreceptor was prepared in the same manner as in Example 1 except that an aluminum drum was used, and evaluation was performed in the same manner as in Example 1. Table 2 shows the results.

Example 4 In Example 1, 20 parts by weight of the hole transporting low molecular weight compound represented by the above structural formula (3) was replaced with 55 parts by weight of the hole transporting high molecular weight compound shown by the following structural formula (4). Alternatively, the electron transporting N-hexyl-
The addition amount of 30 parts by weight of N'-cyclohexyl-1,4,5,8-naphthalenetetracarboxylic diimide was changed to 42 parts by weight, and bisphenol Z type polycarbonate (PC-Z, manufactured by Mitsubishi Gas Chemical Company) was added. An electrophotographic photoreceptor was prepared in the same manner as in Example 1 except that the evaluation was not performed, and the evaluation was performed in the same manner as in Example 1. Table 2 shows the results.

[0108]

Embedded image The weight average molecular weight of the used hole transporting polymer compound was 60,000.

Example 5 Preparation of Electrophotographic Photoreceptor Electrophotography was performed in the same manner as in Example 4 except that the diameter of the aluminum drum (conductive support) was changed to a diameter of 84 mm. A photoreceptor was produced.

-Evaluation (Evaluation of image quality and durability)-The obtained photoreceptor was commercialized using a full-color laser copying machine (A
-Color 935, manufactured by Fuji Xerox Co., Ltd.), and printing was performed continuously for 1000 sheets in the A4 horizontal direction in a normal temperature and normal humidity environment (20 ° C., 50% RH), and a copy test was performed. 1
The image quality and durability were evaluated by visually observing the print sample after the 1000th print and the 1000th continuous print. Table 2 shows the results. The laser copying machine used for evaluation was provided with a charger for negative charging and a developing device of a reversal developing system.

Comparative Example 1 In Example 1, the electron-transporting N-hexyl-N′-cyclohexyl-1,
Except that 4,5,8-naphthalenetetracarboxylic acid diimide was not used, and the addition amount of the hole transporting low molecular weight compound represented by the above structural formula (3) was changed to 50 parts by weight, the same as Example 1 was carried out. An electrophotographic photoreceptor was prepared and evaluated in the same manner as in Example 1. Table 2 shows the results.

Comparative Example 2 Preparation of Electrophotographic Photoreceptor In an X-ray diffraction spectrum using CuKα as a radiation source, at least a Bragg angle (2θ ± 0.2 °) was 7.4.
3 parts by weight of chlorogallium phthalocyanine microcrystals having strong diffraction peaks at 0 °, 16.6 °, 25.5 °, and 28.3 ° were mixed with a vinyl chloride-vinyl acetate-maleic anhydride copolymer (VMCH, Union Carbide). 3 parts by weight), 60 parts by weight of xylene, and 40 parts by weight of butyl acetate. The mixture was dispersed with SUS beads by a paint shake method for 5 hours, and the resulting dispersion was mirror-finished. It was applied to the surface of an aluminum drum (conductive support) having a diameter of 30 mm by a dip coating method, and dried by heating at 115 ° C. for 5 minutes to form a 0.2 μm-thick charge generation layer.

Next, 50 parts by weight of the hole transporting low molecular weight compound represented by the structural formula (3), bisphenol Z type polycarbonate (PC-Z, manufactured by Mitsubishi Gas Chemical Company) 5
0 parts by weight, 40 parts by weight of cyclohexanone, and 1,2
-Dichloroethane (360 parts by weight) was mixed to prepare a coating solution for forming a charge transport layer. The obtained coating solution is applied on the charge generation layer by a dip coating method,
After heating and drying for 15 minutes, a monopolar charge transport layer having a thickness of 15 μm was formed, and an electrophotographic photosensitive member having a function-separated laminated structure was manufactured.

-Evaluation (Evaluation of Image Quality and Durability)-The obtained electrophotographic photosensitive member was evaluated in the same manner as in Example 1. Table 2 shows the results.

Comparative Example 3 In Comparative Example 2, the surface was roughened (arithmetic average roughness: Ra = 0.20 μm) by a wet honing treatment using alumina particles as an aluminum drum (conductive support). An electrophotographic photosensitive member was prepared in the same manner as in Comparative Example 2 except that an aluminum drum having a diameter of 30 mm was used, and evaluation was performed in the same manner as in Example 1. Table 2 shows the results.

Comparative Example 4 In Example 1, N, N'-cyclohexyl-1,4,5,8-naphthalenetetracarboxylic diimide was replaced with N, N'-cyclohexyl-N'-cyclohexyl-1,4,5,8-naphthalenetetracarboxylic diimide.
Except that dihexyl-1,4,5,8-naphthalenetetracarboxylic acid diimide was used, an electrophotographic photoreceptor was prepared and evaluated in the same manner as in Example 1. Crystals were remarkably precipitated during heating and drying. The evaluation could not be performed. It is shown in Table 2.

(Comparative Example 5) In Example 1, instead of N-hexyl-N'-cyclohexyl-1,4,5,8-naphthalenetetracarboxylic diimide, N, N'-
An electrophotographic photoreceptor was prepared and evaluated in the same manner as in Example 1 except that dicyclohexyl-1,4,5,8-naphthalenetetracarboxylic acid diimide was used. The evaluation could not be performed. It is shown in Table 2.

[0118]

[Table 2]

As described above, the electrophotographic photoreceptor of the present invention has excellent effects of high performance and long life. As a result, it can be seen that the electrophotographic apparatus provided with the electrophotographic photosensitive member of the present invention has high repetition stability and provides stable high image quality for a long period of time. Also, regardless of the surface properties of the conductive support, there is no occurrence of interference fringes,
Furthermore, since it has an excellent property that image quality defects such as density unevenness do not occur even if a rough conductive support is used and an undercoat layer is not used, a problem in a conventional electrophotographic photosensitive member having a function-separated laminated structure. It can be seen that has been dispelled. In addition, it can be seen that the asymmetrically substituted diimide-based electron transporting compound of the present invention has significantly higher amorphousness than the conventional symmetrical structure due to its asymmetric structure.

[0120]

According to the present invention, an electron transporting property,
By utilizing a novel electron transport material having excellent compatibility with a resin, chemical stability, and the like, an electrophotographic photosensitive member having high performance and long life can be provided at low cost. Specifically, it is possible to provide an electrophotographic photoreceptor capable of being charged to a positive polarity and a bipolar polarity, and to use an electrophotographic photoreceptor having the above-described excellent characteristics, to provide a high-quality and highly durable process cartridge, and An electrophotographic device can be provided.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view showing a part of an electrophotographic photoconductor as an example of the present invention.

FIG. 2 is a schematic cross-sectional view showing a part of an electrophotographic photoconductor as another example of the present invention.

FIG. 3 is a schematic cross-sectional view showing a part of an electrophotographic photoconductor as another example of the present invention.

FIG. 4 is a schematic configuration diagram illustrating an example of the electrophotographic apparatus of the present invention.

[Explanation of symbols]

 1: conductive support 2: charge generation layer 3: charge transport layer 4: fine particles made of a charge generation material 11: photoconductor drum (electrophotographic photoconductor) 12: static elimination LED (static elimination light source) 13: charging scorotron (Charging unit) 14: Laser optical system for exposure (image exposure unit) 15: Developing unit 16: Contact charging roll for transfer 17: Cleaning blade (Cleaning unit) 18: Paper

Claims (3)

[Claims] 1. An electrophotographic photoreceptor comprising a layer containing an N, N ′ heterosubstituted aromatic tetracarboxylic diimide compound represented by the following general formula (1). RN (CO) ₂ X (CO) ₂ NR ′ ... General formula (1) In general formula (1), X represents a tetravalent group having a substituted or unsubstituted aromatic ring structure. R and R 'represent different hydrocarbon groups or heteroatom-containing hydrocarbon groups, and these groups are not based on imide groups and π-electron conjugation. 2. A process cartridge having the electrophotographic photosensitive member according to claim 1, which is detachable from an electrophotographic apparatus. 3. An electrophotographic apparatus comprising the electrophotographic photosensitive member according to claim 1 or the process cartridge according to claim 2.