JPH06138678A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To provide an electrophotographic sensitive body excellent in sensitivity and repetitive characteristics. CONSTITUTION:An electric charge transferring material represented by formula I or II is used in a photosensitive layer. In formula I, each of R1-R4 is H, halogen, alkyl or alkoxy and each of R5 and R6 is optionally substd. aryl. In formula II, each of R13-R16 is H, halogen, alkyl or alkoxy and each of R11, R12, R17, and R18 is optionally substd. aryl.

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, there is provided a photosensitive layer, which comprises a dithienylbenzene derivative represented by the following general formula (I):

[0007]

[Chemical 3]

(In the formula, R ₁ , R ₂ , R ₃ and R ₄ each represent a hydrogen atom, a halogen atom, an alkyl group or an alkoxy group, and R ₅ and R ₆ each represent a substituted or unsubstituted aryl group. According to the second invention, it is achieved by having a photosensitive layer, and the photosensitive layer contains a dithienylbenzene derivative represented by the following general formula (II).

[0009]

[Chemical 4]

(In the formula, R ₁₃ , R ₁₄ , R ₁₅ and R ₁₆ each represent a hydrogen atom, a halogen atom, an alkyl group or an alkoxy group, and R ₁₁ , R ₁₂ , R ₁₇ and R ₁₈ are substituted or unsubstituted. Represents the aryl group of.)

[0011]

There is no known example in which the dithienylbenzene derivative represented by the general formula (I) or (II) is used in the photosensitive layer. The present inventors have conducted various experiments on these dithienylbenzene derivatives while earnestly examining various organic materials in order to achieve the above object, and as a result, their technical elucidation has not yet been satisfactorily achieved. It was found that the use of a dithienylbenzene derivative having a specific structure represented by the general formula (I) or (II) as a charge transport material is extremely effective in improving electrophotographic characteristics, and it was repeated with high sensitivity. Thus, a photoconductor having excellent characteristics was obtained.

[0012]

EXAMPLES The dithienylbenzene derivative of the general formula (I) or (II) used in the present invention can be synthesized by a conventional method. That is, the following general formula (III
) Or (IV) and a reagent represented by the following general formula (V) are reacted in a suitable organic solvent (eg, dimethylformamide, dimethoxyethane, etc.) in the presence of an alkali to easily synthesize can do.

[0013]

[Chemical 5]

Specific examples of the dithienylbenzene derivative represented by the general formula (I) are shown below.

[0015]

[Chemical 6]

[0016]

[Chemical 7]

[0017]

[Chemical 8]

Specific examples of the dithienylbenzene derivative represented by the general formula (II) are shown below.

[0019]

[Chemical 9]

The photoreceptor of the present invention contains the above-mentioned dithienylbenzene derivative in the photosensitive layer.
Depending on the application of these dithienylbenzene derivatives, they can be used as shown in FIG. 1, FIG. 2 or FIG. 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 photoconductor according to the embodiment of the present invention, and FIG. 3 is an embodiment of the present invention. FIG. 3 is a cross-sectional view showing a positively-charged laminated type photoreceptor according to 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 in which a dithienylbenzene derivative which is a charge transporting substance 5 is dispersed in a resin binder (binder) (a structure usually referred to as a single-layer type photoreceptor) is provided. FIG. 2 shows a photosensitive layer 21 (including a charge generation layer 4 mainly composed of a charge generation substance 3 and a charge transport layer 6 containing a dithienylbenzene derivative which is a charge transport substance 5 on a conductive substrate 1 ( A structure generally referred to as a laminated type photoreceptor is provided.

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 layer structure of FIG. 2 which is usually used as a negative charging system is used in the positive charging system, a charge transporting material suitable for this is still found. This is because the layer structure shown in FIG. 3 is required at the present stage as a positive charging type photoreceptor.

The photoreceptor 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 coating the 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 photoreceptor of FIG. 3, a solution in which a charge transport material and a resin binder are dissolved is applied onto a conductive substrate and dried, and the charge generating material is vacuum-deposited on the conductive material, or particles of the charge generating material are formed. It can be prepared by coating a dispersion obtained by dispersing in a solvent or a resin binder, drying, and then forming a coating layer. The conductive substrate 1 serves not only as an electrode of the photoconductor but also as a support for each of the other layers, and may be cylindrical, plate-shaped, or film-shaped, and made of aluminum, stainless steel, nickel, or the like. A metal, glass, resin, or the like that has been subjected to a conductive treatment can 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 generate a 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 coating film in which the dithienylbenzene derivative represented by the general formula (I) or (II) is dispersed as an organic charge transport substance in a resin binder, and as a dielectric layer in a dark place. It retains the charge of the photoconductor and exhibits the function of transporting the charge injected from the charge generation layer when receiving light. As the resin binder, polymers, copolymers of polycarbonate, polyester, polystyrene, methacrylic acid ester and the like 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 the light to which the charge generation layer is sensitive, and transmits the 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 such that the residual potential does not increase when repeatedly used continuously. Example 1 50 parts by weight of x-type metal-free phthalocyanine (H ₂ Pc) and the dithienylbenzene derivative 1 represented by the chemical formula I-1.
00 parts by weight of 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 by a wire-bar method onto an aluminum vapor-deposited polyester film (Al-PET) which is a conductive substrate, and a film thickness after drying. A photoconductor was prepared so that Example 2 100 parts by weight of the dithienylbenzene derivative represented by the chemical formula I-2 and 100 parts by weight of a polycarbonate resin (trade name Panlite L-1225: manufactured by Teijin Chemicals) were dissolved in methylene chloride. The coating liquid was applied on a aluminum vapor-deposited polyester film substrate with a wire bar to form a charge transport layer so that the film thickness after drying was 15 μm. On the charge transport layer thus obtained, 1
Titanyl phthalocyanine (TiOP
c) 50 parts by weight of polyester resin (trade name: Byron 2
(00: Toyobo) 50 parts by weight together with THF solvent for 3 hours
A coating solution was prepared by kneading with a mixer and applied with a wire bar to form a charge generation layer so that the film thickness after drying was 1 μm. Example 3 In Example 2, the following structural formula (V
A photoconductor was prepared in the same manner as in Example 2 except that the squarylium compound represented by the formula (I) was used and the charge transport material was replaced by the dithienylbenzene derivative represented by the chemical formula II-1.

[0029]

[Chemical 10]

Example 4 In Example 2, TiOPc was replaced with, for example, a bisazo pigment, chlorodiamble, and the charge transporting material was replaced with the dithienylbenzene derivative represented by the chemical formula I-4. Similarly, a photoconductor was prepared. 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 potential V _S (V) of the photoconductor is + in the dark.
It is the initial surface potential when the surface of the photoconductor is positively charged by corona discharge of 6.0 kV, and then the time until the surface potential is halved by irradiating the surface of the photoconductor with white light with an illuminance of 2 lx (s ) Is obtained, and the half-attenuation exposure amount E _1/2 (lx · s)
And Further, the surface potential when white light having an illuminance of 2 lx was irradiated for 10 s was defined as the residual potential V _r (V). Further, in Examples 1 to 3, since high sensitivity for long-wavelength light can be expected, electrophotographic characteristics when using monochromatic light having a wavelength of 780 nm were also measured. That is, instead of white light, 1 μW monochromatic light (780 nm) is irradiated to obtain a half-attenuated exposure amount (μJ / cm ² ), and the residual potential V _r ( V) was measured.
The measurement results are shown in Table 1.

[0032]

[Table 1] As can be seen from Table 1, Examples 1, 2, 3, and 4 show comparable characteristics with respect to the half-attenuation exposure amount and the residual potential, and the surface potential shows good characteristics. In addition, in Examples 1 to 3, high sensitivity is exhibited even with long-wavelength light having a wavelength of 780 nm, and it can be seen that the present invention can be sufficiently used for semiconductor laser printers. Example 5 As in Example 2, 50 parts by weight of x-type metal-free phthalocyanine and 50 parts by weight of vinyl chloride copolymer (trade name MR-110: manufactured by Zeon Corporation) were kneaded together with methylene chloride in a mixer for 3 hours to obtain a coating solution. Was prepared and coated on an aluminum support to a thickness of about 1 μm to form a charge generation layer. Next, 100 parts by weight of the dithienylbenzene derivative represented by the chemical formula I-6, 100 parts by weight of a polycarbonate resin (Panlite L-1250), and silicon oil 0.1.
1 part by weight is mixed with methylene chloride, and about 1 is added on the charge generation layer.
The charge transport layer was formed by coating so as to have a thickness of 5 μm.

The photosensitive member thus obtained had good results such as Vs = -780 V and E _1/2 = 2.2 lxs. Example 6 In Example 5, the metal-free phthalocyanine was replaced with a bisazo pigment represented by the following structural formula (VII), and the charge transport material was replaced with the dithienylbenzene derivative represented by the chemical formula II-2. A photoconductor was prepared in the same manner as in.

The photosensitive member thus obtained had good results such as Vs = -680V and E _1/2 = 3.0 lx · s.

[0035]

[Chemical 11]

[0036]

According to the present invention, since the dithienylbenzene derivative represented by the above general formula (I) or (II) is used as the charge transporting material on the conductive substrate, it is highly sensitive even in positive charging and negative charging. Moreover, a photoreceptor having excellent repeating characteristics can be obtained. 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 Generating Material 4 Charge Generating Layer 5 Charge Transporting Material 6 Charge Transporting Layer 7 Covering Layer 20 Photosensitive Layer 21 Photosensitive Layer 22 Photosensitive Layer

Claims (7)

[Claims] 1. A photosensitive layer, which has the following general formula (I):
A photoconductor for electrophotography, comprising the dithienylbenzene derivative represented by as a charge transporting substance. [Chemical 1] (In the formula, R ₁ , R ₂ , R ₃ and R ₄ each represent a hydrogen atom, a halogen atom, an alkyl group or an alkoxy group, and R ₅ and R ₆ each represent a substituted or unsubstituted aryl group.) 2. A photosensitive layer, which has the following general formula (II):
A photoconductor for electrophotography, comprising the dithienylbenzene derivative represented by as a charge transporting substance. [Chemical 2] (In the formula, R ₁₃ , R ₁₄ , R ₁₅ and R ₁₆ each represent a hydrogen atom, a halogen atom, an alkyl group or an alkoxy group,
R ₁₁ , R ₁₂ , R ₁₇ and R ₁₈ each represent a substituted or unsubstituted aryl group. ) 3. The electrophotographic photoreceptor according to claim 1, wherein the photosensitive layer is a laminate of a charge generation layer and a charge transport layer. 4. The electrophotographic photoreceptor according to claim 1, wherein R _{1 of the} dithienylbenzene derivative is a methyl group,
A photoreceptor for electrophotography, wherein R ₂ , R ₃ and R ₄ are each a hydrogen atom, and R ₅ and R ₆ are each a p-tolyl group. 5. The electrophotographic photoconductor according to claim 1.
The dithienylbenzene derivative is R₁, R_FourIs methyl
Group, R₂, R₃, Are hydrogen atoms, R respectively_Five, R ₆Gazo
Electrophotographic feeling characterized by phenyl groups
Light body. 6. The electrophotographic photosensitive member according to claim 2, wherein the dithienylbenzene derivative is R ₁₁ , R ₁₂ , R ₁₇ or R.
_A photoreceptor for electrophotography, wherein ₁₈ is a phenyl group, R ₁₃ and R ₁₆ are methyl groups, and R ₁₄ and R ₁₅ are hydrogen atoms. 7. The electrophotographic photosensitive member according to claim 2, wherein the dithienylbenzene derivative has R ₁₁ and R ₁₈ each being a phenyl group, and R ₁₂ and R ₁₇ each being a p-tolyl group,
A photoreceptor for electrophotography, wherein R ₁₃ and R ₁₆ are each a hydrogen atom, and R ₁₄ and R ₁₅ are each a methyl group.