JP3522436B2 - Electrophotographic photoreceptor - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photosensitive layer of an electrophotographic photoreceptor, and more particularly to a charge transport material used in the photosensitive layer.

[0002]

2. Description of the Related Art Conventionally, as a photosensitive material for an electrophotographic photoreceptor (hereinafter also referred to as a photoreceptor), an inorganic photoconductive substance such as selenium or a selenium alloy, or an organic photoconductive substance such as a phthalocyanine compound or a bisazo compound is used as a resin. Those dispersed in a binder or the like and those vacuum-deposited are used.

The photoconductor is required to have a function of holding a surface charge in a dark place, a function of receiving light to generate a charge, and a function of receiving light to transport a charge, but with one layer. A so-called single-layer type photoreceptor having these functions together,
There is a so-called laminated type photoreceptor in which functionally separated layers are laminated mainly on a layer that contributes to charge generation and a layer that contributes to holding surface charges in a dark place and transporting charges when receiving light. For example, the Carlson method is applied to the image formation by the electrophotographic method using these photoconductors. Image formation by this method is performed by corona discharge to a photoconductor in a dark place, formation of an electrostatic latent image such as characters and pictures of an original on the charged photoconductor surface,
The formed electrostatic latent image is developed with toner, and the developed toner image is fixed on a support such as paper, and the photoconductor after the toner image transfer is neutralized, residual toner is removed, and optical neutralization is performed. And then reused.

In recent years, many applications of photoconductive organic compounds having excellent charge transporting ability to photoconductors have been proposed due to advantages such as flexibility, thermal stability, and film forming property. For example, as an oxadiazole compound, US Pat.
No. 7, as a pyrazoline compound, Japanese Patent Publication No. 59-2
No. 023, and as a hydrazone compound, Japanese Patent Publication No.
Various charge transport materials are known from JP-A 5-42380, JP-A-57-101844 and JP-A-54-150128.

[0005]

As described above, the organic material has many advantages that the inorganic material does not have, but at the same time, an organic material sufficiently satisfying all the characteristics required for the electrophotographic photoreceptor can be obtained. However, there is a problem with the sensitivity and the characteristics during repeated continuous use. The present invention has been made in view of the above points, and its object is to use a new organic material which has never been used as a charge transporting material in a photosensitive layer, and thus has high sensitivity and excellent repeating characteristics. An object is to provide an electrophotographic photoreceptor for a copying machine and a printer.

[0006]

According to the first aspect of the present invention, the above object is achieved by having a photosensitive layer, and the photosensitive layer containing a thiophene derivative represented by the general formula (I) as a charge transporting substance. To be done.

[0007]

[Chemical 5]

[R in the formula (I)¹, R², R³, R^Four． R
^Five, R⁶ _,R⁷Are hydrogen atom, halogen atom,
It represents a alkyl group, an aryl group or an alkoxy group. R²
And R ⁷May form a ring. ] According to the second invention, it has a photosensitive layer, and the photosensitive layer is represented by the general formula
The thiophene derivative represented by (II) is used as a charge transport material.
It is achieved by including.

[0009]

[Chemical 6]

[In the formula (II), R ¹¹ , R ¹² , R ¹³ , R ^{14 ...} R
¹⁵ , R ¹⁶ _, R ¹⁷ , R ¹⁸ , R ¹⁹ _and R ²⁰ each represent a hydrogen atom, a halogen atom, an alkyl group, an aryl group or an alkoxy group. R ¹⁵ and R ²⁰ may form a ring. Further, according to the third invention, it has a photosensitive layer, and the photosensitive layer is achieved by containing a dithienylbenzene derivative represented by the general formula (VII) as a charge transporting substance.

[0011]

[Chemical 7]

[In the formula (VII), R ²¹ , R ²² , R ²³ , R ²⁴ .
R ²⁵ and R ²⁶ each represent a hydrogen atom, a halogen atom, an alkyl group, an aryl group or an alkoxy group. Further, according to the fourth aspect of the invention, the photosensitive layer has a photosensitive layer, and the photosensitive layer is achieved by containing a dithienylbenzene derivative represented by the general formula (VIII) as a charge transporting substance.

[0013]

[Chemical 8]

[In the formula ( VIII ), R ³¹ , R ³² ,
R ³³ , R ³⁴ , R ³⁵ , R ³⁶ , R ³⁷ , R ³⁸ , R
³⁹ is a hydrogen atom, a halogen atom, an alkyl group,
It represents an aryl group or an alkoxy group. ] General formula (I)
Specific examples of the thiophene dielectric material represented by (II) include the chemical formulas (I-1) to (I-11) and the chemical formulas (II).
-1) to chemical formula (II-12).

[0015]

[Chemical 9]

[0016]

[Chemical 10]

[0017]

[Chemical 11]

[0018]

[Chemical 12]

Specific examples of the dithienylbenzene dielectric represented by the general formula ( VII ) or (VIII) are represented by the chemical formula (VII-
1) to chemical formula (VII-16), chemical formula (VIII-1)
To the chemical formula (VIII-16).

[0020]

[Chemical 13]

[0021]

[Chemical 14]

[0022]

[Chemical 15]

[0023]

[Chemical 16]

No example is known in which a thiophene dielectric represented by the general formula (I) or (II) and a dithienylbenzene dielectric represented by the general formula (VII) or (VIII) are used in a photosensitive layer. The present inventors have conducted various experiments on these thiophene dielectrics or dithienylbenzene derivatives as a result of extensive studies on various organic substances in order to achieve the above-mentioned object, and as a result, their technical elucidation has not yet been sufficiently clarified. However, the formula (I) or (I
Use of a thiophene dielectric material having a specific structure shown in I) or a dithienylbenzene derivative having a specific structure shown in the general formula (VII) or (VIII) as a charge transport material improves electrophotographic properties. Therefore, they have found that they are extremely effective, and have obtained a photoreceptor having high sensitivity and excellent repeatability.

[0025]

BEST MODE FOR CARRYING OUT THE INVENTION The thiophene derivative used in the present invention can be synthesized by a usual method. That is, the compound represented by the general formula (I) is obtained by mixing the aldehyde represented by the following general formula (III) and the compound represented by the general formula (IV) in a suitable solvent (dimethylformamide, dimethoxyethane, etc.) in the presence of an alkali. Synthesize by reacting.

The compound represented by the general formula (II) is obtained by reacting the aldehyde represented by the following general formula (V) and the compound represented by the general formula (VI) with a suitable solvent (dimethylformamide, dimethoxyethane, etc.). ) And react to synthesize.

[0027]

[Chemical 17]

[0028]

[Chemical 18]

The dithienylbenzene derivative used in the present invention can be synthesized by a usual method. That is, the compound represented by the general formula (VII) is obtained by mixing the aldehyde represented by the following general formula (IX) and the compound represented by the general formula (X) in a suitable solvent (dimethylformamide, dimethoxyethane, etc.) in the presence of an alkali. Synthesize by reacting.

The compound represented by the general formula (VIII) is a compound represented by the general formula (XII) with an aldehyde represented by the following general formula (XI).
In the presence of an alkali, the compound shown in is reacted in a suitable solvent (dimethylformamide, dimethoxyethane, etc.) to synthesize.

[0031]

[Chemical 19]

[0032]

[Chemical 20]

FIG. 1 is a sectional view showing a single-layer type photoconductor according to an embodiment of the present invention. FIG. 2 is a sectional view showing a negatively-charged laminated type photoreceptor according to the embodiment of the present invention. FIG. 3 is a cross-sectional view showing a positively charged laminated type photoreceptor according to an embodiment of the present invention. 1 is a conductive substrate, 20, 21 and 22 are photosensitive layers,
3 is a charge generating substance, 4 is a charge generating layer, 5 is a charge transporting substance, 6 is a charge transporting layer, and 7 is a coating layer.

FIG. 1 shows a charge generation material 3 on a conductive substrate 1.
And a photosensitive layer 20 (referred to as a single-layer type photoreceptor) in which a thiophene dielectric that is a charge transport material 5 is dispersed in a resin binder (binder). FIG. 2 shows a charge generation layer 4 mainly composed of a charge generation substance 3 on a conductive substrate 1.
And a charge transport layer 6 containing a thiophene dielectric, which is a charge transport material 5, and a photosensitive layer 21 (referred to as a stacked type photoreceptor).

FIG. 3 shows a layer structure opposite to that of FIG.
In this case, it is general to further provide a coating layer 7 to protect the charge generation layer 4. The reason for using the two types of layer structures shown in FIGS. 2 and 3 is that even if the positive charging system is used in the layer structure of FIG. This is because the layer structure shown in FIG. 3 is required at the present stage as a positive charging type photoreceptor.

The photoconductor of FIG. 1 can be prepared by dispersing a charge generating substance in a solution in which a charge transporting substance and a resin binder are dissolved, and applying this dispersion on a conductive substrate. The photoreceptor of FIG. 2 is obtained by vacuum-depositing a charge-generating substance on a conductive substrate, or by applying a dispersion obtained by dispersing particles of the charge-generating substance in a solvent or a resin binder, and drying it. It can be prepared by applying and drying a solution in which a charge transport substance and a resin binder are dissolved.

In the photoconductor of FIG. 3, a solution in which a charge transporting substance and a resin binder are dissolved is applied onto a conductive substrate and dried, and then the charge generating substance is vacuum-deposited, or particles of the charge generating substance and It can be prepared by applying a dispersion obtained by dispersing a resin in a solvent, drying it, and then forming a coating layer. The conductive substrate 1 serves as an electrode of the photoconductor and at the same time serves as a support for each of the other layers.
It may be in the form of a plate or a film, and as the material thereof, a metal such as aluminum, stainless steel, or nickel, or a material obtained by subjecting glass, resin, or the like to a conductive treatment may be used.

The charge generation layer 4 is formed by coating a material in which particles of the charge generation substance 3 are dispersed in a resin binder as described above, or by a method such as vacuum deposition, and receives light to charge. To occur. In addition, it is important that the charge generation efficiency is high, and at the same time, the generated charge is injectable into the charge transport layer 6 and the coating layer 7, and the electric field dependence is small and it is desirable that the injection is good even in a low electric field. As the charge generating substance, phthalocyanine compounds such as metal-free phthalocyanine and titanyl phthalocyanine, dyes such as various azo, quinone, indigo pigments or cyanine, squarylium, azurenium and pyrylium compounds, selenium or selenium compounds, etc. are used for image formation. A suitable substance can be selected according to the light wavelength region of the exposure light source used. Since the charge generation layer only needs to have a charge generation function,
The film thickness is determined by the light absorption coefficient of the charge generating substance and is generally 5 μm or less, preferably 1 μm or less. The charge generation layer may be mainly composed of a charge generation substance and a charge transporting substance or the like may be added thereto. Resin binders include polycarbonate, polyester,
Polyamide, polyurethane, vinyl chloride, phenoxy resin, polyvinyl butyral, diallyl phthalate resin,
Polymers and copolymers of methacrylic acid ester can be appropriately combined and used.

The charge transport layer 6 is a resin binder containing an organic charge transporting substance represented by the general formula (I) or the general formula (I).
A thiophene dielectric represented by I) or the general formula (VII
) Or a dithienylbenzene derivative represented by the general formula (VIII) is dispersed, which holds the charge of the photoconductor as an insulating layer in a dark place and suppresses the charge injected from the charge generating layer at the time of receiving light. Demonstrate the function of transportation. Resin binders include polycarbonate, polyester,
Polymers and copolymers of polystyrene and methacrylic acid ester can be used.

The coating layer 7 has a function of receiving and holding a charge of corona discharge in a dark place, and also has a property of transmitting a light to which the charge generating layer is sensitive, and transmits a light at the time of exposure,
It is necessary to reach the charge generation layer and receive the injection of the generated charges to neutralize and eliminate the surface charges. As the coating material, an organic insulating film forming material such as polyester or polyamide can be applied. Further, these organic materials may be mixed and used with a glass resin, an inorganic material such as SiO _2, or a material such as a metal or a metal oxide that reduces electric resistance. As described above, it is desirable that the coating material be as transparent as possible in the wavelength region of the maximum light absorption of the charge generating substance.

The film thickness of the coating layer itself depends on the compounding composition of the coating layer, but can be arbitrarily set within a range that does not cause adverse effects such as increase in residual potential when repeatedly and continuously used.

[0042]

【Example】

Example 1 40 parts by weight of x-type metal-free phthalocyanine (H ₂ Pc) and 100 parts by weight of the thiophene dielectric material represented by the chemical formula I-3 were added to 100 parts by weight of a polyester resin (trade name: Byron 200: Toyobo) and tetrahydrofuran (THF). ) Kneading with a solvent for 3 hours with a mixer to prepare a coating liquid,
Aluminum vapor-deposited polyester film (A
1-PET) was coated by the wire bar method to prepare a photoconductor so that the film thickness after drying would be 15 μm. Example 2 100 parts by weight of the thiophene dielectric material represented by the chemical formula I-5 and a polycarbonate resin (trade name: Panlite L-1)
225: manufactured by Teijin Chemicals Ltd.) A coating solution prepared by dissolving 100 parts by weight of methylene chloride in a methylene chloride is applied onto a substrate of aluminum vapor-deposited polyester film with a wire bar, and the film thickness after drying is 15 μm.
The charge transport layer was formed so as to have m.

On the charge transport layer thus obtained,
T: 50 parts by weight of titanyl phthalocyanine (TiOPc) crushed by a ball mill for 150 hours and 50 parts by weight of a polyester resin (trade name: Byron 200: Toyobo)
Knead with a HF solvent for 3 hours with a mixer to prepare a coating solution, apply with a wire bar, and dry to a film thickness of 1μ.
The charge generation layer was formed so as to have a thickness of m.

Further, 200 parts by weight of metal alkoxide (trade name Atron NSi-310: Nippon Soda), 10 parts by weight of modified polyamide (trade name CM-8000: Toray), 10 parts by weight of polyurethane resin (trade name Nippon Polyurethane Industry Co., Ltd.) Was dried with 90 parts by weight of ethanol for 1 hour and then polyisocyanate resin (trade name Takenate D1
65N90CX: Takeda Pharmaceutical Co., Ltd.) 2 parts by weight are added and mixed for 30 minutes to prepare a coating solution for the coating layer, and the coating layer is formed on the charge generation layer by the dip method so that the dry film thickness is 1 μm. did. Example 3 The thiophene dielectric material represented by the chemical formula I-5 of Example 2 was replaced with the thiophene dielectric material represented by the chemical formula II-5 as a charge transport material, and TiOPc was replaced with chlorodiazine blue as a charge generation material. A photoconductor was prepared in the same manner as in Example 2 except that it was used.

The electrophotographic characteristics of the photoconductor thus obtained were measured by the electrostatic recording paper testing apparatus "SP-428" manufactured by Kawaguchi Electric Co., Ltd.
Was measured using. The surface potential Vs (V) of the photoconductor is the initial surface potential when the photoconductor surface is positively charged by a corona discharge of +6.0 kV in a dark place, and then the photoconductor surface is irradiated with white light with an illuminance of 2 lx. Then, the time (s: seconds) until the surface potential becomes half is obtained and the half-attenuation exposure amount E
_{It was set to 1/2} (lx · s). Moreover, Example 1 and Example
2 can expect high sensitivity for long-wavelength light, the wavelength is 780
The electrophotographic characteristics when monochromatic light of nm was used were also measured. That is, instead of white light, 1 μW monochromatic light (780
nm) and a half-attenuation exposure amount E _1/2 (μJ / c
m ² ) was calculated. The results are shown in Table 1.

[0046]

[Table 1]

As can be seen in Table 1, Examples 1, 2, 3
Shows that the half-attenuation exposure amount and the residual potential are not inferior to each other and shows good characteristics. Further, in Examples 1 and 2, the wavelength 78
It shows high sensitivity even with long wavelength light of 0 nm, and it can be seen that it can be sufficiently used for semiconductor laser printers. Again 1
Even when the test was repeated 000 times, the change in the surface potential Vs was 50 V or less, and the half-attenuated exposure amount E _1/2 was also unchanged and stable. Example 4 50 parts by weight of metal-free phthalocyanine (H ₂ Pc) and 50 parts by weight of vinyl chloride copolymer (trade name MR-110: manufactured by Nippon Zeon Co., Ltd.) were kneaded together with methylene chloride for 3 hours in a mixer for 1 μm on an aluminum substrate. Was applied to form a charge generation layer.

Next, 100 parts by weight of the thiophene derivative represented by the chemical formula (I-8), 100 parts by weight of a polycarbonate resin (Panlite L-1225), and silicon oil 0,
1 part by weight is mixed with methylene chloride to form 1 on the charge generation layer.
The charge transport layer was formed by coating so as to have a thickness of 5 μm.
The electrophotographic characteristics of the photoconductor thus obtained were measured by using an electrostatic recording paper test device “SP-428” manufactured by Kawaguchi Electric.

The surface of the photosensitive member was negatively charged by corona discharge of -6.0 kV, and the electrophotographic characteristics were measured using monochromatic light having a wavelength of 780 nm. Initial surface potential Vs is -75
A good result was obtained with 0 V and a half-attenuation exposure amount E _1/2 of 1.5 μJ / cm ² . Example 5 In Example 4, the metal-free phthalocyanine (H ₂ Pc) was replaced with the bisazo pigment represented by the following chemical formula, and the thiophene derivative represented by the chemical formula (I-8) was replaced with the chemical formula (II-5). A photoreceptor was prepared in the same manner as in Example 4 except that the thiophene derivative shown was used.

The obtained photoreceptor was measured by changing the monochromatic light to white light. Vs is -740V, half-attenuation exposure amount E _1/2
Is 1.4 lx · s, which is a good result.

[0051]

[Chemical 21]

Example 6 In Example 4, the metal-free phthalocyanine (H ₂ Pc) was replaced by the bisazo pigment represented by the following chemical formula, and the thiophene derivative represented by the chemical formula (I-8) was replaced by the chemical formula (II- A photoconductor was produced in the same manner as in Example 4 except that the thiophene derivative shown in 7) was used.

The obtained photoreceptor was measured by changing the monochromatic light to white light. Vs is -750V, half-attenuation exposure amount E _1/2
Is 1.5 lx · s, which is a good result.

[0054]

[Chemical formula 22]

Example 7 In Example 4, a metal-free phthalocyanine (H ₂ Pc) was replaced with a squarylium compound represented by the following chemical formula, and a thiophene derivative represented by the chemical formula (I-8) was replaced with the chemical formula (II- A photoconductor was produced in the same manner as in Example 4 except that the thiophene derivative shown in 7) was used.

The obtained photoreceptor was measured by changing the monochromatic light to white light. Vs is -740V, half-attenuation exposure amount E _1/2
Is 1.3 lx · s, which is a good result.

[0057]

[Chemical formula 23]

Example 8 50 parts by weight of x-type metal-free phthalocyanine (H ₂ Pc) and 100 parts by weight of the dithienylbenzene dielectric represented by the above chemical formula VII-3 were added to a polyester resin (trade name: Byron 20).
0: 100 parts by weight of Toyobo and tetrahydrofuran (T
HF) Kneading with a solvent for 3 hours with a mixer to prepare a coating solution, which is applied onto an aluminum vapor-deposited polyester film (Al-PET) which is a conductive substrate by a wire-bar method, and a film after drying. A photoreceptor was prepared so that the thickness was 15 μm. Example 9 100 parts by weight of the dithienylbenzene dielectric represented by the chemical formula VII-4 and 100 parts by weight of a polycarbonate resin (trade name Panlite L-1225: manufactured by Teijin Kasei) were dissolved in methylene chloride. The coating solution was applied onto an aluminum-deposited polyester film substrate with a wire bar to form a charge transport layer so that the film thickness after drying was 20 μm. On the charge transport layer thus obtained, titanyl phthalocyanine (Ti) pulverized by a ball mill for 150 hours was processed.
OPc) 50 parts by weight and polyester resin (trade name Byron 200: manufactured by Toyobo) 50 parts by weight are kneaded with a THF solvent for 3 hours by a mixer to prepare a coating solution, which is applied with a wire bar and dried to obtain a film thickness. The charge generation layer was formed to have a thickness of 1 μm. Example 10 The dithienylbenzene dielectric represented by the chemical formula VII-4 in Example 9 was replaced with the dithienylbenzene dielectric represented by the chemical formula VIII-7 as a charge transport material, and TiOPc
A photosensitive member was prepared in the same manner as in Example 9 except that the squarylium compound represented by the following chemical formula was used as the charge generating substance.

[0059]

[Chemical formula 24]

Example 11 The dithienylbenzene dielectric represented by the chemical formula VII-4 in Example 9 was replaced with the dithienylbenzene dielectric represented by the chemical formula VIII-12 as a charge transport material, and TiOP was used.
A photoconductor was prepared in the same manner as in Example 9 except that chlorodian blue was used as the charge generating substance instead of c.

The electrophotographic characteristics of the thus obtained photoconductor were measured by the electrostatic recording paper testing apparatus "SP-428" manufactured by Kawaguchi Denki Co., Ltd.
Was measured using. The surface potential V _S (V) of the photoconductor is the initial surface potential when the surface of the photoconductor is positively charged by a corona discharge of +6.0 kV in a dark place, and then white light with an illuminance of 2 lx is applied to the surface of the photoconductor. The time (s: seconds) until the surface potential becomes half after irradiation is calculated and the half-attenuation exposure amount E _1/2 (lx
・ S). Further, in Examples 8 to 10, high sensitivity for long-wavelength light can be expected, and therefore, electrophotographic characteristics when monochromatic light having a wavelength of 780 nm was used were also measured. That is, 1 μW of monochromatic light (780 nm) was irradiated instead of white light to determine the half-attenuated exposure amount E _1/2 (μJ / cm ² ). The results are shown in Table 2.

[0062]

[Table 2]

As seen in Table 2, Examples 8, 9, 1
Nos. 0 and 11 show no difference in half-exposure exposure amount and residual potential and show good characteristics. In addition, in Examples 8 to 10, high sensitivity is exhibited even with long-wavelength light having a wavelength of 780 nm, and it can be seen that it can be sufficiently used for a semiconductor laser printer. Also, in the 1000-time repeated test, the change of the surface potential Vs was 60 V or less, and the half-attenuated exposure amount E _1/2 was also unchanged and stable. Example 12 50 parts by weight of metal-free phthalocyanine (H ₂ Pc) and 50 parts by weight of vinyl chloride copolymer (trade name MR-110: manufactured by Nippon Zeon) were kneaded together with methylene chloride for 3 hours in a mixer for 1 μm on an aluminum substrate. Was applied to form a charge generation layer.

Next, 100 parts by weight of the dithienylbenzene derivative represented by the chemical formula (VII-13), 100 parts by weight of a polycarbonate resin (trade name BP-PC: manufactured by Idemitsu Kosan),
Mix 0.1 part by weight of silicone oil with methylene chloride,
A 20 μm thick coating was applied on the charge generation layer to form a charge transport layer. The charge of the photoreceptor thus obtained is
The characteristics of the sub-picture can be measured by Kawaguchi Denki's electrostatic recording paper testing device "SP-4.
28 ". -6.0kV on the surface of photoconductor
Negatively charged by the corona discharge of
The electrophotographic properties were measured using colored light. Initial surface potential Vs is -700 V, half-attenuation exposure amount E _1/2 is 1.5 μJ.
/ Cm ² , which was a good result. In addition, the change of the surface potential Vs was 40 V even in the repeated test of 1000 times.
The following were good. Example 13 Metal-free phthalocyanine (H ₂ Pc) in Example 12
In the same manner as in Example 12 except that the bisazo pigment represented by the following chemical formula is used instead of the dithienylbenzene derivative represented by the chemical formula (VII-13) and the dithienylbenzene derivative represented by the chemical formula (VII-14) is used instead of the dithienylbenzene derivative represented by the chemical formula (VII-13). Then, a photoconductor was prepared.

The obtained photoreceptor was changed from monochromatic light to white light.
The measurement was performed. The initial surface potential Vs was −750 V and the half-attenuated exposure dose E _1/2 was 1.3 lx · s, which was a good result. In addition, the change in the surface potential Vs was good at 40 V or less even in the 1000-time repeated test.

[0066]

[Chemical 25]

Example 14 Metal-free phthalocyanine (H ₂ Pc) in Example 12
In the same manner as in Example 12 except that the bisazo pigment represented by the following chemical formula is used instead of the dithienylbenzene derivative represented by the chemical formula (VII-13) and the dithienylbenzene derivative represented by the chemical formula (VIII-6) is used. Then, a photoconductor was prepared.

The obtained photoreceptor was changed from monochromatic light to white light.
The measurement was performed. The initial surface potential Vs was −750 V and the half-attenuation exposure amount E _1/2 was 1.6 lx · s, which was a good result. In addition, the change in the surface potential Vs was good at 40 V or less even in the 1000-time repeated test.

[0069]

[Chemical formula 26]

[0070]

According to the present invention, a photosensitive layer is provided, and the photosensitive layer is a thiophene derivative represented by the general formula (I) or (II) or a dithienylbenzene represented by the general formula (VII) or (VIII). Since the dielectric is used as the charge transport material, it is possible to obtain a photoreceptor having high sensitivity even in positive charging and negative charging and excellent in repeating characteristics. Further, as the charge generating substance, a suitable substance can be selected according to the type of the exposure light source. For example, a phthalocyanine compound, a squarylium compound and a certain bisazo compound can be used as a photoconductor which can be used as a semiconductor laser printer. Can be obtained. Further, if necessary, a coating layer may be provided on the surface to improve durability.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a single-layer type photoconductor according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a negatively charged layered photoconductor according to an embodiment of the present invention.

FIG. 3 is a cross-sectional view showing a positively charged laminated type photoreceptor according to an embodiment of the present invention.

[Simple explanation of symbols]

1 Conductive substrate 3 Charge generation material 4 Charge generation layer 5 Charge transport materials 6 Charge transport layer 7 coating layer 20 Photosensitive layer 21 Photosensitive layer 22 Photosensitive layer

─────────────────────────────────────────────────── ─── Continuation of front page (56) Reference JP-A-6-138678 (JP, A) JP-A-7-56368 (JP, A) JP-A-4-136949 (JP, A) JP-A-58- 123542 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G03G 5/00-5/16 CAPLUS (STN) REGISTRY (STN)

Claims (4)

(57) [Claims] 1. A photosensitive layer having a photosensitive layer represented by the general formula (I).
Thiophene derivative as a charge transport material
A photoconductor for electrophotography, which is characterized by: [Chemical 1] [R in Formula (I)¹, R², R³, R^Four． R^Five, R⁶ _,R
⁷Are hydrogen atom, halogen atom, alkyl group, and
Represents a reel group or an alkoxy group. R²And R ⁷Is a ring
You may form. ] 2. An electrophotographic photoreceptor having a photosensitive layer, wherein the photosensitive layer contains a thiophene derivative represented by the general formula (II) as a charge transporting substance. [Chemical 2] [R ¹¹ , R ¹² , R ¹³ , R ^{14 in} Formula (II). R ¹⁵ , R ¹⁶ _, R
¹⁷ , R ¹⁸ , R ¹⁹ _and R ²⁰ each represent a hydrogen atom, a halogen atom, an alkyl group, an aryl group or an alkoxy group. R ¹⁵ and R ²⁰ may form a ring. ] 3. A photoreceptor for electrophotography, comprising a photosensitive layer, wherein the photosensitive layer contains a dithienylbenzene derivative represented by the general formula (VII) as a charge transporting substance. [Chemical 3] [In the formula (VII), R ²¹ , R ²² , R ²³ , R ²⁴ . R ²⁵ and R ²⁶ each represent a hydrogen atom, a halogen atom, an alkyl group, an aryl group or an alkoxy group. ] 4. An electrophotographic photoreceptor having a photosensitive layer, which contains a dithienylbenzene derivative represented by the general formula ( VIII ) as a charge transporting substance. [Chemical 4] [In Formula ( VIII ), R ³¹ , R ³² , R ³³ , R ³⁴ , R
³⁵ , R ³⁶ , R ³⁷ , R ³⁸ and R ³⁹ each represent a hydrogen atom, a halogen atom, an alkyl group, an aryl group or an alkoxy group. ]