JPH07261436A - Electrophotographic photoreceptor - Google Patents

Abstract

PURPOSE:To provide a high sensitive electrophotographic photoreceptor widely used for a high speed copying machine, a printer, a facsimile or the like. CONSTITUTION:This electrophotorgraphic photoreceptor contains an imidazol perylene compound expressed by formula 1 or II, which is present in the photoreceptor in a crystalline state that the crystal has peaks at 6.3+ or -0.2 deg., 12.4+ or -0.2 deg., 25.3+ or -0.2 deg., 27.1+ or -0.2 deg. in X-ray diffraction spectrum to Cu-K alpha-ray, the peak intensity is max. at 12.4+ or -0.2 deg., the half-value width of the same peak is >=0.66 and the peak at 11.5+ or -0.2 deg. is not clearly shown, and is allowed to contain a compound expressed by formula III as a carrier transfer material. In the formula III, each of Ar1-Ar4 represents an aromatic hydrocarbon group, or a heterocyclic group, R2 represents either hydrogen atom or an aromatic hydrocarbon group or a heterocyclic group. n represents 1 or 2.

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, and more particularly to a high-sensitivity photosensitive member effective for printers, copying machines and the like.

[0002]

2. Description of the Related Art As a photoreceptor for an electrophotographic system, there are an inorganic photoreceptor containing an inorganic photoconductive substance such as selenium and cadmium sulfide as a main component and an organic photoreceptor containing various organic photoconductive compounds as a main component. It can be roughly divided. Conventionally, inorganic photoconductors with excellent sensitivity characteristics have been used for high-speed copying machines, but there are major restrictions due to the toxicity of manufacturing raw materials and product compounds, and in recent years it has become a harmless organic photoconductor from the viewpoint of environmental protection. The demand for replacement is becoming stronger. Based on such a trend, there is a strong demand for higher performance of organic photoconductors, and technical development for higher sensitivity has become an urgent issue.

The most general method used to improve the performance of the organic photoconductor is a function separation technique in which different substances are separately assigned the function of generating photocarriers and the function of transporting photocarriers. By allowing carriers to be generated and carriers to be transported by different substances, it is possible to select a substance suitable for each substance from a wide range. In particular, since organic photoconductors have a wide variety of compounds, they are advantageous in achieving high performance by such functional separation, and many carrier generating substances and carrier transporting substances have been proposed.

Examples of carrier-generating substances for organic photoreceptors include polycyclic quinone compounds typified by dibromoanthanthrone, phthalocyanine compounds such as metal-free phthalocyanine and titanyl phthalocyanine, bisazo compounds and trisazo compounds, thiapyrylium compounds and polycarbonates. The eutectic complex, squarerium compound, etc. have been put to practical use. Further, as the carrier transporting substance, for example, a pyrazoline compound, a polyarylalkane compound, a triphenylamine compound, a hydrazone compound, a tetraphenylbenzidine compound, a styryl compound and the like have been put into practical use.

Among them, the performance of the carrier-generating substance directly determines the sensitivity characteristics, but the basic function of absorbing the incident light to generate electron carriers depends on the molecular structure of the carrier-generating substance. Not only is it dependent, but it is also significantly affected by the aggregate morphology of those molecules. For example, many crystal polymorphs are known for the above-mentioned metal-free phthalocyanine and titanyl phthalocyanine, and even if the molecular structure is the same, the quantum efficiency of carrier generation is completely different when the crystal types are different, resulting in a large difference in electrophotographic sensitivity. Can be seen. The X-type crystal and τ-type crystal of metal-free phthalocyanine show a one-order higher sensitivity than the α-type crystal and the β-type crystal, and the Y-type crystal of titanyl phthalocyanine is A
It is well known that the sensitivity is 3 to 4 times higher than that of the B-type crystal and the B-type crystal. Similarly, in azo compounds and squarylium compounds, the sensitivity changes remarkably due to the difference in the molecular aggregation structure.

As described above, in the development of the carrier generating substance, the optimization of the crystal structure or the molecular aggregation structure is an essential element as well as the optimization of the chemical structure.

The imidazole perylene compound of the structural formula (1) or (2) which constitutes the present invention is disclosed in JP-B-61-8423.
No. 3 (US Pat. No. 3,972,717), a technique of using it as a carrier generating substance has been disclosed, and many electrophotographic photoreceptors using this compound as a carrier generating substance have been studied thereafter. Japanese Unexamined Patent Publication No. 59-59686 discloses a technique for producing a photoconductor by mainly coating the present compound in a dispersed manner.
848 (US Pat. No. 4,587,189), JP-A-63-180956,
JP 63-291061 A, JP 4-186363 A, JP 4-18636 A
No. 4 discloses a technique of using this compound in combination with a specific carrier-transporting substance. In addition, JP-A-64-56444
Japanese Unexamined Patent Publication No. 4-204850 discloses a technique for atomizing this compound by acid paste treatment.
No. 41054 discloses a technique in which a perylene-based compound containing this compound is used after being purified by sublimation.

However, in these conventional techniques, since the crystal state of the present compound has not been examined, sufficient sensitivity characteristics cannot be obtained, and it has not been possible to meet the recent demand for higher sensitivity. .

Regarding the crystal form of the compound of structural formula (1) or (2), some X-ray diffraction spectra are disclosed in J. Imag. Sci., Vol.33, P151-159 (1989). . However, these are related to powder crystals, and in the study by the present inventors, when a photoconductor coating solution was prepared using these powders, the photoconductor coating was dependent on the conditions for preparing the coating solution and the chemical purity. The X-ray diffraction spectrum of the product changes,
At the same time, it became clear that the characteristics of the photoconductor also changed significantly.

From such a viewpoint, Japanese Patent Laid-Open Nos. Hei 5-249719 and Hei 5-281769 disclose techniques for controlling the crystalline state of the compound. These techniques control the crystal state by the dry crushing method, but such dry crushing has a strong local shearing force, which causes a problem in homogenizing the crushing and causes black spots in the electrophotographic image. It has the drawback of being prone to occur. Further, since dry pulverization has a large mechanical impact on the crystal powder, crystal defects are likely to be introduced, and as a result, the charge potential holding ability is lowered. Thus, the crystal control technology is still insufficient for this compound,
Its performance has not been brought out.

On the other hand, the carrier transporting material used in combination with such a carrier generating material is an important factor that determines the performance of the photoconductor. Not only the sensitivity performance but also the physical properties of the photosensitive layer required when it is used as an electrophotographic photoreceptor are greatly changed depending on the carrier transporting substance. Japanese Unexamined Patent Publication No. Hei 5-249719 and Japanese Unexamined Patent Publication No. Hei 5-281769 disclose a technique using a benzidine-based carrier transport material,
The photoreceptor prepared by containing this compound has a problem that microscopic cracks (called cracks) in the photosensitive layer are likely to occur and image defects due to the cracks are likely to appear.

[0012]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an electrophotographic photoreceptor having high sensitivity and excellent image stability, which can be widely used in high speed copying machines, printers, fax machines and the like.

[0013]

The object of the present invention is achieved by the following constitution.

[1] In a photoconductor containing at least the imidazole perylene compound represented by the structural formula (1) or (2), the imidazole perylene compound is Cu-Kα.
X-ray diffraction spectrum 6.3 ± 0.2 °, 12.4 ± 0.
A crystal having peaks at 2 °, 25.3 ± 0.2 °, and 27.1 ± 0.2 °, the peak intensity at 12.4 ± 0.2 ° is maximum, and at the same time, the half width of the peak is 0.65 ° or more, and 11.5 ±.
An electrophotographic photoreceptor characterized by being present in a state where it does not show a clear peak at 0.2 °,

[0015]

[Chemical 5]

Further, structural formulas (3), (4),
By using the compound represented by (5) or (6) as a carrier-transporting substance, a photoreceptor having excellent sensitivity characteristics and image stability can be obtained. Especially, when the carrier transporting material of the general formula (3) is used, particularly high sensitivity characteristics are obtained.

[0017]

[Chemical 6]

In the formula, Ar ₁ , Ar ₂ , Ar ₃ and Ar ₄ represent a substituted or unsubstituted aromatic hydrocarbon group or heterocyclic group,
R ₂ represents a hydrogen atom or a substituted or unsubstituted aromatic hydrocarbon group or heterocyclic group. n is 1 or 2. Preferred as the aromatic hydrocarbon group or heterocyclic group are benzene, naphthalene, anthracene, thiophene, pyridine and carbazole, and particularly preferred are benzene and naphthalene. Substituents on the aromatic hydrocarbon group or heterocyclic group include alkyl, aryl, alkoxy, aryloxy, acyl, acyloxy, halogen,
Amino, cyano and the like can be mentioned, but particularly preferred is
Alkyl having 1 to 6 carbons, alkoxy having 1 to 6 carbons,
Acyl, halogen, and amino having 1 to 6 carbon atoms. Further, Ar ₄ and R ₂ may be bonded to each other.

[0019]

[Chemical 7]

In the formula, R ₃ and R ₄ represent a substituted or unsubstituted aromatic hydrocarbon group, a heterocyclic group or an alkyl group, and R ₅ represents a hydrogen atom or a substituted or unsubstituted aromatic hydrocarbon group or a heterocyclic group. Represents a cyclic group or an alkyl group, and Ar ₅ represents a substituted or unsubstituted aromatic hydrocarbon group or heterocyclic group. m is 0 or 1. Preferred examples of R ₃ and R ₄ include a methyl group, an ethyl group, a phenyl group, a naphthyl group and a thienylmethyl group. R ₅ is preferably a hydrogen atom or a phenyl group. Ar ₅ is preferably benzene, naphthalene, pyrene, thiophene, pyridine or carbazole, and particularly preferably benzene, pyrene or carbazole. As the substituent for Ar ₅ , alkyl having 1 to 6 carbon atoms, dialkylamino and diarylamino are preferable.

[0021]

[Chemical 8]

In the formula, Y is substituted or unsubstituted benzene, naphthalene, pyrene, fluorene, carbazole, and 4,
Indicates a 4'-alkylidene diphenyl group. Ar ₆ and Ar ₇ represent a substituted or unsubstituted aromatic hydrocarbon group or heterocyclic group. l is an integer of 1 to 3.

The substituent on Y is preferably an alkyl group having 1 to 6 carbon atoms. Ar ₆ and Ar ₇ are preferably benzene, and the substituent is preferably alkyl having 1 to 6 carbons, aryl, alkoxy or aryloxy.

[0024]

[Chemical 9]

In the formula, Ar ₈ , Ar ₉ , Ar ₁₀ and Ar ₁₁ represent a substituted or unsubstituted aromatic hydrocarbon group or a heterocyclic group, but benzene is particularly preferable, and the substituent thereof is dialkylamine, Diarylamine is preferred.

The general formulas (3), (4), (5), and
Specific examples of the carrier transport substance represented by (6) are shown below.

[0027]

[Chemical 10]

[0028]

[Chemical 11]

[0029]

[Chemical 12]

[0030]

[Chemical 13]

[0031]

[Chemical 14]

[0032]

[Chemical 15]

[0033]

[Chemical 16]

[0034]

[Chemical 17]

[0035]

[Chemical 18]

[0036]

[Chemical 19]

Regarding the crystal form of the imidazole perylene compound used in the present invention, see J. Imag. Sci., Vol.33, P151-
159 (1989) discloses four types of X-ray diffraction spectra called α, γ, ε and ρ. Basically, α-type and ε-type have similar crystal structures, but it is clear that ρ-type is a completely different crystal. The crystalline state of the present invention is based on this ρ-type crystal. The change in state that occurs in the step of dispersing and atomizing the ρ-type crystal in an organic solvent significantly affects the sensitivity characteristics.

In general, in order to obtain high-sensitivity photoconductor characteristics, it is first necessary to obtain a uniform coating film in which carrier generating substances are atomized. That is, in the dispersion atomization step, the first important thing is to atomize the carrier generating substance.

When the crystallite size becomes smaller than a certain size due to the dispersion atomization, broadening of the diffraction peak and reduction of the peak intensity occur in the X-ray diffraction spectrum. The ρ-type crystal of the imidazole perylene compound is C
In the X-ray diffraction spectrum for u-Kα rays, 6.3 ±
The peaks at 0.2 °, 12.4 ± 0.2 °, 25.3 ± 0.2 °, and 27.1 ± 0.2 ° are characteristic, but there are other peculiar peaks at 11.5 ± 0.2 °. Broadening of the entire peak can be observed when the ρ-type crystal is dispersed and atomized, but it is particularly important in the present invention that the half value width of the peak at 12.4 ± 0.2 ° is 0.65 ° or more. , 11.5 ± 0.2 ° with a peak of 12.4 ± 0.2 ° thus broadened
It is necessary that the peak of 1 is buried and no peak is observed in the region of 11.5 ± 0.2 °. However, 12.4 ± 0.2
When the half-width of the ° peak exceeds 1.5 °, it cannot be said to be a ρ-type crystalline state.

The photoconductor characteristics of the imidazole perylene compound of the present invention depend on the crystalline state characterized by the relative intensity of peaks in the X-ray diffraction spectrum. The imidazole perylene compound was 6.3 at the stage of synthesis.
In many cases, the peak intensity around ° is maximum, and in the case of sublimation, the peak intensity between 25 and 28 ° is maximum.
The peak intensity at 12.4 ° may be maximum. However, when these are dispersed and atomized in an organic solvent, the relative intensity of each peak changes, and therefore the characteristics of the photoconductor change.
The crystal of the present invention can obtain particularly excellent sensitivity characteristics by maximizing the peak intensity of 12.4 ± 0.2 ° of the X-ray diffraction spectrum.

That is, in the present invention, 12.4 ± 0.2 of ρ-type crystal
The half-width of the ° peak is 0.65 ° or more, and 11.5 ± 0.
A state in which the peak intensity at 12.4 ± 0.2 ° is the maximum is used after atomizing to a state where no clear peak is shown at 2 °.

By using the carrier generating substance in such a state in combination with the carrier transporting substance specified in the present invention, excellent sensitivity effect and repeated stability can be obtained. The method for obtaining the crystalline state is not particularly limited, but the most excellent method for preventing the defect of the electrophotographic image as seen in the dry pulverization method is an acid paste using a sublimated imidazole perylene compound with sulfuric acid. It is subjected to a treatment (amorphization or low crystallization), and is gently dispersed in an organic solvent having a high affinity with a polymer binder interposed therebetween to grow a crystal into an intended crystal state. In this method, uniform atomization is achieved, and since mechanical impact is small, deterioration of characteristics due to the introduction of crystal defects can be avoided.

The imidazole perylene compound of the structural formula (1) or (2) can be synthesized by a dehydration condensation reaction of perylene-3,4,9,10-tetracarboxylic dianhydride and o-phenylenediamine.

The synthesized imidazole perylene compound is subjected to sublimation purification to remove impurities. The sublimation operation is repeated once to about 5 to 6 times, but it is desirable to repeat the sublimation operation twice or more. When the coating liquid is prepared without sublimation purification, it is difficult to obtain the crystalline state of the present invention. The imidazole perylene compound obtained by sublimation shows a sharp peak pattern in the X-ray diffraction spectrum, and it is confirmed that the crystallinity is high.

The high crystallinity imidazole perylene compound obtained by sublimation purification is converted to a low crystallinity state by performing an acid paste treatment using sulfuric acid. That is, after dissolving in concentrated sulfuric acid, the solution is poured into a poor solvent such as water or methanol to cause precipitation, which is filtered and dried to obtain a low crystalline fine particle powder.

The low crystalline powder after the acid paste treatment is subjected to a dispersion treatment in a solvent having a high affinity for the imidazole perylene compound using a suitable disperser. As a solvent having high affinity, a ketone solvent having 4 to 8 carbon atoms, a cyclic ether solvent having 4 to 7 carbon atoms or 2 carbon atoms
Halogenated hydrocarbon solvents of ~ 4 are useful. Among them, particularly preferable solvents include methyl ethyl ketone, methyl isopropyl ketone, methyl isobutyl ketone, cyclohexanone, tetrahydrofuran, dichloroethane and trichloroethane. Also, the presence of a suitable binder polymer can give good results in this dispersion process.

Particularly preferable binder polymers are polyvinyl acetal resins such as polyvinyl vicillal and polyvinyl formal, vinyl chloride-vinyl acetate resins, polyester resins, polycarbonate resins, acrylic resins and methacrylic resins, acrylic and methacrylic copolymer resins, silicone resins. , Silicone copolymer resin, polystyrene, styrene copolymer resin, phenoxy resin, phenol resin, urethane resin, epoxy resin and the like.

The specific crystal state of the present invention is realized in the dispersion coating liquid obtained by such a method. In this method, high purification by sublimation purification is important for adjusting the crystalline state during dispersion, and further it is made amorphous by acid paste treatment with sulfuric acid, and in the process of dispersion treatment, it is in an amorphous state (or low crystalline state). )
Therefore, the crystal is grown by a specific solvent effect, which makes it possible to stably obtain the specific crystal state of the present invention from a completely different viewpoint from the conventional one.

A photoreceptor is prepared using the obtained dispersion coating solution. Whether the crystalline state of the present invention is realized in the photoconductor can be confirmed by measuring the X-ray diffraction spectrum of the imidazole perylene compound peeled from the photoconductor. Further, since the crystal state does not change in the process of coating the photoreceptor, it can be confirmed by removing the solvent from the dispersion coating solution and measuring the X-ray diffraction spectrum.

These samples are measured by a powder X-ray diffraction measuring apparatus using Cu-Kα ray as an X-ray source, and a diffraction line intensity distribution is obtained as a function of Bragg angle 2θ. At this time, when the sample amount is sufficient, the relative intensity ratio between the peak intensities does not change depending on the sample amount, but when the sample amount decreases, the peak intensity on the low angle side relatively increases. Therefore, in the measurement, a sufficient amount of sample must be used so that the peak intensity ratio does not change with the sample amount.

The peak intensity here is, as shown in FIG. 2, the intersection point d of the line segment connecting the rising points a and b from the baseline level containing noise and the perpendicular line drawn from the vertex c.
It is defined by the height to the vertex c (the length of the line segment cd) when the origin is. The full width at half maximum of the peak is defined as the peak width at the height of cd / 2 with the point d as the starting point.

The structure of the photoconductor can take various forms. Typically, the configuration is as shown in FIGS. In the case of FIG. 1A, the carrier generation layer 2 is formed on the conductive support 1, and the carrier transport layer 3 is laminated on the carrier generation layer 2 to form the photosensitive layer 4, and FIG. 1B shows the carrier. A photosensitive layer 4'in which the generation layer 2 and the carrier transport layer 3 are reversed is formed. 1C shows an intermediate layer 5 provided between the photosensitive layer 4 and the conductive support 1 in the layer structure of FIG. 1A, and FIG. 1D shows a photosensitive layer in the layer structure of FIG. An intermediate layer 5 is provided between 4'and the conductive support 1. FIG. 3E shows a photosensitive layer 4 ″ containing a carrier generating substance 6 and a carrier transporting substance 7, and FIG. 3F shows such a photosensitive layer 4 ″ and a conductive support 1. The intermediate layer 5 is provided between them. 1 (a)-(f)
In the above constitution, a protective layer can be further provided on the outermost layer.

The carrier generating layer can be formed by a bar coating method, a spin coating method, an applicator coating, a spray coating, a dip coating or the like, using the dispersion coating solution whose crystal state is adjusted as described above. An ultrasonic disperser as a device useful for dispersing the carrier-generating substance,
A ball mill, sand mill, homomixer, paint shaker or the like can be used. It is useful to use a binder for forming the carrier generation layer.

The carrier transporting layer can be formed by using a liquid in which a carrier transporting substance is dissolved in a solvent and by the same coating method as described for the carrier generating layer.
A polymer binder is preferably used in order to improve the mechanical properties of the photosensitive layer film, and it is used by dissolving it in a solvent together with a carrier transporting substance.

The ratio of the carrier transport material to the binder is set to 10 to 500% by weight, preferably 20 to 150% by weight. The thickness of the carrier generation layer is 0.01 to 20 μm, more preferably 0.05 to 5 μm. The thickness of the carrier transport layer is set to 1 to 100 μm, more preferably 5 to 50 μm.

Polymers useful as a binder for the carrier transport layer and the intermediate layer include, for example, polycarbonate, acrylic resin, methacrylic resin, polyvinyl chloride,
Vinyl chloride copolymer resin, polyvinylidene chloride, polystyrene, styrene copolymer, polyvinyl acetate, polyvinyl formal, polyvinyl butyral, polyvinyl acetal, polyvinyl carbazole, silicone resin, silicone copolymer resin, polyester, phenoxy resin, phenol resin, polyurethane , Epoxy resin, and the like.

As the conductive support, a metal plate or a metal drum may be used, and a conductive polymer, a conductive compound such as indium oxide, or a thin layer of a metal such as aluminum or palladium may be applied, vapor deposition, lamination, or the like. What is provided on a substrate such as paper or plastic film can be used.

The above-mentioned photosensitive layer may contain an electron-accepting substance for the purpose of improving sensitivity, reducing residual potential, or reducing fatigue during repeated use. Examples of such an electron accepting substance include succinic anhydride, maleic anhydride, dibromosuccinic anhydride, phthalic anhydride, tetrachlorophthalic anhydride, tetrabromophthalic anhydride, 3-nitrophthalic anhydride and 4-nitrophthalic anhydride. Acid, pyromellitic dianhydride, mellitic dianhydride, tetracyanoethylene, tetracyanoquinodimethane, o-dinitrobenzene, m-dinitrobenzene, 1,3,5-trinitrobenzene, p-nitrobenzonitrile, vicryl chloride, Quinone chlorimide, chloranil, bromanil, dichlordicyano-p-benzonequinone, anthraquinone, dinitroanthraquinone, 9-
Fluorenylidene malonodinitrile, polynitro-9-fluorenylidene malonodinitrile, picric acid, o-nitrobenzoic acid, p-nitrobenzoic acid, 3,5-dinitrobenzoic acid, pentafluorobenzoic acid, 5-nitrosalicylic acid , 3,
Examples thereof include 5-dinitrosalicylic acid, phthalic acid, mellitic acid, and other compounds having a high electron affinity. Addition ratio of electron-accepting substance is 100 weight of carrier generating substance
However, 0.01 to 200 is preferable, and 0.1 to 100 is more preferable.

[0059]

EXAMPLES Next, the present invention will be specifically described with reference to Examples.

In this example, "parts" means "parts by weight" unless otherwise specified.

(Synthesis Example) Perylene-3,4,9,10-tetracarboxylic dianhydride 39.2 g, o-phenylenediamine 32.4 g,
800 ml of α-chlornaphthalene was mixed and reacted at 260 ° C for 6 hours. After cooling, the precipitated crystals were collected by filtration and repeatedly washed with methanol. After heating and drying, 51.1 g of an imidazole perylene compound as a mixture of structural formulas (1) and (2) was obtained. The thus obtained product is called a synthetic product, and its X-ray diffraction spectrum is shown in FIG.

(Sublimation Example) The imidazole perylene compound obtained in the Synthesis Example was subjected to a pressure of 5 × 10 ^{−4 to} 5 × 10 ⁻³ torr.
Sublimation purification was performed under heating conditions of 500 ° C. Volatile impurities were removed using a shutter. The obtained purified crystals were subjected to the same sublimation treatment once more to be further purified.
The product that has undergone the two sublimation operations in this way is called a sublimation product, and its X-ray diffraction spectrum is shown in FIG.

(Example of Acid Paste Treatment) A solution prepared by dissolving 20 g of a sublimated imidazole perylene compound in 600 ml of concentrated sulfuric acid was filtered through a glass filter and then dropped into 1200 ml of pure water for precipitation. This was collected by filtration, washed thoroughly with pure water, and then dried. The thus obtained product is called an AP product (acid paste treated product), and its X-ray diffraction spectrum is shown in FIG.

Example 1 An imidazole perylene compound AP product 7 was placed in a sand mill device filled with glass beads.
g, Polyvinyl butyral resin "ESREC BLS"
(Sekisui Chemical Co., Ltd.) 1.5 g, methyl ethyl ketone 250 ml
Was put in and dispersed for 15 hours. A part of the thus obtained dispersion was concentrated to dryness and the X-ray diffraction spectrum was measured. Results are shown in FIG. The peak intensity at 12.4 ± 0.2 ° was the maximum, and the full width at half maximum was 0.86 °. Also 11.5 ± 0.2 °
No clear peak was observed.

The obtained dispersion is applied on a polyester base on which aluminum is vapor-deposited using a wire bar,
A carrier generation layer having a thickness of 0.3 μm was formed. Next, 1 part of carrier transporting material B-23; polycarbonate "Z-20"
0] (manufactured by Mitsubishi Gas Chemical Co., Inc.) was dissolved in 10 parts of 1,2-dichloroethane using a blade coating machine and dried, and then a carrier transport layer having a thickness of 25 μm was formed. The photoconductor thus obtained is referred to as Sample 1.

Example 2 Dispersion treatment was carried out in the same manner as in Example 1 except that 250 ml of 1,2-dichloroethane was used instead of methyl ethyl ketone, and the X-ray diffraction spectrum of the resulting dispersion was measured. It is shown in FIG. 12.4 ± 0.2 °
Had the maximum peak intensity, and the half-width was 0.94 °.
No clear peak was observed at 11.5 ± 0.2 °. Further, using this dispersion, a photoreceptor was prepared in the same manner as in Example 1. This is sample 2.

Example 3 Dispersion treatment was performed in the same manner as in Example 1 except that 250 ml of tetrahydrofuran was used instead of methyl ethyl ketone, and the X-ray diffraction spectrum of the resulting dispersion was measured. It is shown in FIG. 12.4 ± 0.2 °
Had the maximum peak intensity and a half-width of 0.68 °.
No clear peak was observed at 11.5 ± 0.2 °. Further, using this dispersion, a photoreceptor was prepared in the same manner as in Example 1. This is sample 3. (Comparative Example 1) A dispersion liquid was obtained in the same manner as in Example 1 except that an ultrasonic disperser was used instead of the sand mill disperser for 5 hours. The result of measuring the X-ray diffraction spectrum of the obtained dispersion liquid is shown in FIG. The crystal growth became excessive and the full width at half maximum of the peak at 12.4 ± 0.2 ° was 0.60 °. A peak was observed at 11.5 ± 0.2 °. Further, using this dispersion, a photoconductor was prepared in the same manner as in Example 1.
This is designated as Comparative Sample (1).

Comparative Example 2 The sublimation product of the imidazole perylene compound was used in place of the AP product, and the same dispersion treatment as in Example 1 was performed, and the X-ray diffraction spectrum of the obtained dispersion liquid was measured. The results are shown in Fig. 10. The full width at half maximum of the peak at 12.4 ± 0.2 ° is 0.68 °, which is 27.
The peak intensity at 1 ± 0.2 ° is greater. Further, using this dispersion, a photoreceptor was prepared in the same manner as in Example 1. This is designated as Comparative Sample (2).

(Comparative Example 3) A sublimation product was used instead of the AP product of the imidazole perylene compound, and a polycarbonate resin "Panlite L" was used instead of the polyvinyl butyral resin.
1250 ”(manufactured by Teijin Chemicals Ltd.) was used, and dispersion treatment was performed in the same manner as in Example 1 except that toluene was used instead of methyl ethyl ketone, and the X-ray diffraction spectrum of the obtained dispersion liquid was measured. It is shown in FIG. The full width at half maximum of the peak at 12.4 ± 0.2 ° is 0.52 °, and the peak intensity at 27.1 ± 0.2 ° is larger than the peak at 12.4 ± 0.2 °. Also 11.5 ±
A peak was observed at 0.2 °. Further, using this dispersion, a photoreceptor was prepared in the same manner as in Example 1. This is designated as Comparative Sample (3).

(Evaluation 1) The samples obtained as described above were evaluated as follows using a paper analyzer EPA-8100 (manufactured by Kawaguchi Electric Co., Ltd.). First, corona charging was performed for 5 seconds under the condition of -6 KV, and the surface potential Va immediately after charging was measured.
Then, the surface potential Vi after standing for 5 seconds is obtained, and then exposure is performed so that the surface illuminance becomes 2 (lux), and the surface potential is set to −6.
Exposure required to reduce from 00V to -100V E600 /
I asked for 100. Further, the dark decay rate D was obtained from the equation of D = 100 (Va-Vi) / Va (%). The results are shown in Table 1.

[0071]

[Table 1]

(Examples 4 to 13) The carrier transport material was B-
23 to B-21, B-8, B-13, B-43, B-46, C-
A photoconductor was prepared in the same manner as in Example 1 except that 5, C-9, D-4, D-15 and E-7 were used. This is sample 4
~ Sample 13

(Comparative Examples 4 to 7) The carrier transporting material was B-
A photoconductor was produced in the same manner as in Example 1 except that the following structural formulas Z-1, Z-2, Z-3, and Z-4 were changed from 23. These are designated as Comparative Sample (4) to Comparative Sample (7).

Comparative Example 8 A dry pulverized product obtained by dry pulverizing a sublimated product for 72 hours in a ball mill instead of the AP product of the imidazole perylene compound was used, and Z- was used instead of the carrier transporting material B-23. Example 1 except that one compound was used
A photoconductor was prepared in the same manner as in. This is designated as Comparative Sample (8). As a result of measuring the X-ray diffraction spectrum of the dispersion liquid, the peak intensity at 12.4 ± 0.2 ° was the maximum and the half value width was 0.67 °. No clear peak was observed at 11.5 ± 0.2 °.

[0075]

[Chemical 20]

(Evaluation 2) The obtained sample was evaluated in the same manner as in Evaluation 1, and then mounted on a copier "U-BIX 3035" remodeling machine (manufactured by Konica Corporation) and repeatedly tested 10,000 times. The image was evaluated by. The results are shown in Table 2.

[0077]

[Table 2]

In the above Examples and Comparative Examples, it was confirmed that the X-ray diffraction spectrum of the imidazole perylene compound collected from the photoconductor samples and measured was in agreement with the X-ray diffraction spectrum of the sample obtained by drying the corresponding dispersion. confirmed. As described above, the imidazole perylene compound exhibits particularly excellent sensitivity characteristics when present in the photosensitive layer in the specific crystalline state in the present invention.

[0079]

According to the present invention, it is possible to provide a highly sensitive electrophotographic photosensitive member which can be widely used in high speed copying machines, printers, fax machines and the like.

[Brief description of drawings]

FIG. 1 is a layer configuration diagram of a photoconductor according to the present invention.

FIG. 2 is a diagram showing the definitions of peak intensity and half width in an X-ray diffraction peak.

FIG. 3 is an X-ray diffraction spectrum of an imidazole perylene compound (synthetic product).

FIG. 4 is an X-ray diffraction spectrum of an imidazole perylene compound (sublimation product).

FIG. 5 is an X-ray diffraction spectrum of an imidazole perylene compound (treated with an acid paste).

FIG. 6 is an X-ray diffraction spectrum of imidazole perylene compound Example 1.

FIG. 7: X-ray diffraction spectrum of imidazole perylene compound Example 2.

FIG. 8 is an X-ray diffraction spectrum of the imidazole perylene compound Example 3.

FIG. 9 is an X-ray diffraction spectrum of an imidazole perylene compound comparative example 1.

FIG. 10 is an X-ray diffraction spectrum of an imidazole perylene compound comparative example 2.

FIG. 11 is an X-ray diffraction spectrum of an imidazole perylene compound comparative example 3.

[Explanation of symbols]

 1 Chargeable Support 2 Carrier Generation Layer 3 Carrier Transport Layer 4, 4 ', 4 "Photosensitive Layer 5 Intermediate Layer 6 Carrier Generation Material 7 Carrier Transport Material

Claims (4)

[Claims] 1. A photoreceptor containing at least an imidazole perylene compound of structural formula (1) or (2), wherein the imidazole perylene compound is 6.3 ± 0.2 ° or 12.4 ± 0.2 ° in an X-ray diffraction spectrum with respect to Cu-Kα radiation. , 2
A crystal having peaks at 5.3 ± 0.2 ° and 27.1 ± 0.2 °, the peak intensity at 12.4 ± 0.2 ° is the maximum, and the half width of the peak is 0.65 ° or more, and 11.5 ± 0.2 °.
And a compound of the structural formula (3) as a carrier-transporting substance. [Chemical 1] In the formula, Ar ₁ , Ar ₂ , Ar ₃ and Ar ₄ represent a substituted or unsubstituted aromatic hydrocarbon group or heterocyclic group, and R ₂ represents a hydrogen atom or a substituted or unsubstituted aromatic hydrocarbon group or heterocyclic group. Represents a ring group. n is 1 or 2. Ar ₄ and R ₂ may be bonded to each other. 2. A photoreceptor containing at least an imidazole perylene compound of structural formula (1) or (2), wherein the imidazole perylene compound is 6.3 ± 0.2 ° or 12.4 ± 0.2 ° in an X-ray diffraction spectrum with respect to Cu-Kα radiation. , 2
A crystal having peaks at 5.3 ± 0.2 ° and 27.1 ± 0.2 °, the peak intensity at 12.4 ± 0.2 ° is maximum, and the half-width of the peak is 0.65 ° or more, and 11.5 ± 0.2 °.
And a compound of structural formula (4) as a carrier-transporting substance. [Chemical 2] In the formula, R ₃ and R ₄ represent a substituted or unsubstituted aromatic hydrocarbon group, heterocyclic group or alkyl group, and may be linked to each other. R ₅ represents a hydrogen atom or a substituted or unsubstituted aromatic hydrocarbon group, heterocyclic group or alkyl group, and Ar ₅ represents a substituted or unsubstituted aromatic hydrocarbon group or heterocyclic group.
m is 0 or 1. 3. A photoreceptor containing at least an imidazole perylene compound of structural formula (1) or (2), wherein the imidazole perylene compound is 6.3 ± 0.2 ° or 12.4 ± 0.2 ° in an X-ray diffraction spectrum with respect to Cu-Kα radiation. , 2
A crystal having peaks at 5.3 ± 0.2 ° and 27.1 ± 0.2 °, the peak intensity at 12.4 ± 0.2 ° is maximum, and the half-width of the peak is 0.65 ° or more, and 11.5 ± 0.2 °.
And an electrophotographic photoreceptor containing the compound of structural formula (5) as a carrier-transporting substance. [Chemical 3] In the formula, Y represents a substituted or unsubstituted benzene, naphthalene, pyrene, fluorene, carbazole or 4,4′-alkylidene diphenyl group, and Ar ₆ and Ar ₇ are substituted or unsubstituted aromatic hydrocarbon groups or heterocycles. Represents a group. l is an integer of 1 to 3. 4. A photoreceptor containing at least an imidazole perylene compound represented by the structural formula (1) or (2), wherein the imidazole perylene compound is 6.3 ± 0.2 ° or 12.4 ± 0.2 ° in an X-ray diffraction spectrum with respect to Cu-Kα rays. , 2
A crystal having peaks at 5.3 ± 0.2 ° and 27.1 ± 0.2 °, the peak intensity at 12.4 ± 0.2 ° is maximum, and the half-width of the peak is 0.65 ° or more, and 11.5 ± 0.2 °.
And a compound of the structural formula (6) as a carrier-transporting substance. [Chemical 4] In the formula, Ar ₈ , Ar ₉ , Ar ₁₀ and Ar ₁₁ represent a substituted or unsubstituted aromatic hydrocarbon group or heterocyclic group.