JP3006329B2 - 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 for the photosensitive layer.

[0002]

2. Description of the Related Art Conventionally, photosensitive materials for electrophotographic photoreceptors (hereinafter also referred to as photoreceptors) include inorganic photoconductive substances such as selenium or selenium alloy, and inorganic photoconductive substances such as zinc oxide or cadmium sulfide. An organic photoconductive material such as poly-N-vinylcarbazole or polyvinylanthracene, an organic photoconductive material such as a phthalocyanine compound or a bisazo compound dispersed in a binder, dispersed in a binder. And vacuum-deposited ones are used.

A photoreceptor is required to have a function of retaining a surface charge in a dark place, a function of receiving light to generate a charge, and a function of receiving light and transporting a charge. A so-called single-layer type photoreceptor that combines these functions and a layer that separates functions into a layer that mainly contributes to charge generation and a layer that contributes to charge retention and surface transport in dark places and charge transport during photoreception. There is a so-called laminated type photoreceptor which is laminated. For image formation by electrophotography using these photoconductors, for example, the Carlson method is applied. Image formation by this method involves charging a photoreceptor by corona discharge in a dark place, forming an electrostatic latent image such as a character or picture of an original on the charged photoreceptor surface, and forming the electrostatic latent image Is performed by fixing the developed toner image to a support such as paper, and the photoreceptor after the transfer of the toner image is subjected to charge elimination, removal of residual toner, and the like, and then reused.

In recent years, many applications of photoconductive organic compounds having excellent charge transporting ability to photoreceptors have been proposed due to their advantages such as flexibility, thermal stability, and film forming properties. For example, oxadiazole compounds include US Pat.
No. 7, as the pyrazoline compound,
No. 2023 and hydrazone compounds described in JP-B-55-42380 and JP-A-57-101844.
Various charge transport materials are known from Japanese Patent Application Laid-Open No. Sho 54-150128 and Japanese Patent Application Laid-Open No. Sho 54-150128.

[0005]

As described above, an organic material has many advantages that an inorganic material does not have, but at the same time, a material that sufficiently satisfies all the characteristics required for an electrophotographic photosensitive member can be obtained. At present, there is a problem in sensitivity and characteristics in repeated continuous use. The present invention has been made in view of the above points, and uses a new organic material that has never been used as a charge transporting material in the photosensitive layer to provide a copy having high sensitivity and excellent repetition characteristics. An object of the present invention is to provide an electrophotographic photoconductor for a machine and a printer.

[0006]

According to a first aspect of the present invention, there is provided a photosensitive layer having at least one compound represented by the following general formula (I):

[0007]

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[Wherein X represents an oxygen atom or a sulfur atom, R ₁ and R ₂ each represent a hydrogen atom, a substituted or unsubstituted alkyl group, an aryl group or a heterocyclic group;
r ₁ and Ar ₂ each represent a substituted or unsubstituted aryl group or heterocyclic group. According to the second aspect of the present invention, there is provided a photosensitive layer having at least one compound represented by the following general formula (II).

[0009]

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[Wherein X represents an oxygen atom or a sulfur atom, R ₃ and R ₄ each represent a hydrogen atom, an alkyl group or a substituted or unsubstituted aryl group, and Ar ₃ represents a substituted or unsubstituted aryl group or Represents a heterocyclic group. ]

[0011]

The use of a styryl compound represented by formula (I) or (II) in a photosensitive layer has not been known. While these inventors have intensively studied various organic materials in order to achieve the above-mentioned object, as a result of conducting numerous experiments on these compounds, their technical elucidation has not yet been sufficiently completed. Formula (I) or (I
It has been found that the use of a compound having a specific skeleton represented by I) as a charge transport material is extremely effective in improving electrophotographic properties, and has resulted in a photoconductor having high sensitivity and excellent repetition properties. It is.

[0012]

The synthesis of the compound represented by formula (I) or (II) used in the present invention can be easily obtained by carrying out a known Wittig reaction. For example, specific examples I-3 and II-12 of the compounds described below are obtained by synthesizing the compounds (a) and (b), and the compounds (c) and (d) shown in the following reaction formulas, respectively.

[0013]

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Specific examples of the compound represented by the above general formula (I) are as follows.

[0015]

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[0016]

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Specific examples of the compound represented by the general formula (II) are as follows.

[0018]

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[0019]

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The photoreceptor of the present invention contains the above-mentioned styryl compound in the photosensitive layer. Depending on the method of applying these derivatives, the photoreceptor shown in FIG. 1, FIG. 2 or FIG.
Can be used as shown in FIG. FIG. 1 is a sectional view showing a single-layer photosensitive member according to an embodiment of the present invention, FIG. 2 is a sectional view showing a negatively charged laminated photosensitive member according to an embodiment of the present invention, and FIG. 3 is an embodiment of the present invention. 1 is a cross-sectional view illustrating a positively-charged laminated photoconductor according to the first embodiment. 1 is a conductive substrate, 20, 2
Reference numerals 1 and 22 are photosensitive layers, 3 is a charge generating material, 4 is a charge generating layer, 5 is a charge transporting material, 6 is a charge transporting layer, and 7 is a coating layer. FIG. 1 shows a configuration in which a photosensitive layer 20 (usually referred to as a single-layer type photosensitive member) in which a charge generating substance 3 and a charge transporting substance 5 are dispersed in a resin binder (binder) is provided on a conductive substrate 1. It is. FIG. 2 shows a photosensitive layer 21 (usually referred to as a laminated photoreceptor) formed by laminating a charge generation layer 4 mainly composed of a charge generation substance 3 and a charge transport layer 6 containing a charge transport substance 5 on a conductive substrate 1. Is provided. FIG. 3 shows the reverse layer configuration of FIG. 2. In this case, it is general that a cover layer 7 is further provided to protect the charge generation layer 4.

The reason why the two kinds of layer constitutions shown in FIGS. 2 and 3 are adopted is that even if an attempt is made to use the layer constitution shown in FIG. This is because it has not been found yet, and it is necessary at this stage to have the layer configuration shown in FIG. 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 applying this dispersion on a conductive substrate.

In the photoreceptor shown in FIG. 2, a charge-generating substance is vacuum-deposited on a conductive substrate, or a dispersion obtained by dispersing particles of the charge-generating substance in a solvent or a resin binder is coated and dried. It can be prepared by applying and drying a solution in which a charge transport material and a resin binder are dissolved.
The photoreceptor in FIG. 3 is prepared by applying a solution in which a charge transporting substance and a resin binder are dissolved on a conductive substrate and drying the solution, and then vacuum-depositing the charge generating substance on the conductive base material, or dissolving the charge generating substance particles in a solvent or resin. It can be prepared by applying and drying a dispersion obtained by dispersing in a binder, and then forming a coating layer.

The conductive substrate 1 serves as a support for the other layers at the same time as serving as an electrode of the photoreceptor, and may be cylindrical, plate-like, or film-like. , A metal such as nickel, or a material obtained by conducting a conductive treatment on glass, resin, or the like. The charge generation layer 4 is formed by applying a material in which particles of the charge generation substance 3 are dispersed in a resin binder as described above,
Alternatively, it is formed by a method such as vacuum evaporation, and receives light to generate charges. In addition, the charge generation efficiency is high, and at the same time, it is important to inject the generated charges into the charge transport layer 6 and the coating layer 7, and it is desirable that the electric field is less dependent on the electric field and the injection is good even at a low electric field. As the charge generating substance, metal-free phthalocyanines, phthalocyanine compounds such as titanyl phthalocyanine, various azo, quinone, indigo pigments or dyes such as cyanine, squarylium, azurenium, pyrylium compounds, selenium or selenium compounds, and the like are used for image formation. A suitable substance can be selected according to the light wavelength range of the exposure light source to be used. Since the charge generation layer only needs to have a charge generation function, its thickness is determined by the light absorption coefficient of the charge generation 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, to which a charge transport substance or the like is added. As the resin binder, polycarbonate, polyester, polyamide, polyurethane, epoxy, silicone resin, methacrylate polymer and copolymer, and the like can be used.

The charge transport layer 6 is a coating film in which the compound represented by the above general formula (I) or (II) is dispersed as an organic charge transport material in a resin binder. It has the function of retaining charge and transporting charge injected from the charge generation layer during photoreception. As the resin binder, polymers and copolymers such as polycarbonate and polyester can be used in appropriate combination.

The coating layer 7 has a function of receiving and holding the charge of corona discharge in a dark place, and has a performance of transmitting light which the charge generation layer responds to.
It is necessary to reach the charge generation layer and neutralize the surface charge by injection of the generated charge. As the coating material, an organic insulating film forming material such as polyester and polyamide can be applied. In addition, these organic materials and SiO
It is also possible to use a mixture of an inorganic material such as ₂ and a material such as a metal or a metal oxide which reduces the electric resistance. The coating material is not limited to an organic insulating film-forming material, but may be an inorganic material such as SiO ₂ or even a metal,
A metal oxide or the like can be formed by a method such as evaporation or sputtering. As described above, it is desirable that the coating material is as transparent as possible in the wavelength region where the light absorption of the charge generating substance is maximum.

Although the thickness of the coating layer itself depends on the mixed composition of the coating layer, it can be arbitrarily set within a range where adverse effects such as an increase in residual potential when used repeatedly and continuously are not caused. _. Example 1 x type metal-free phthalocyanine (H ₂ Pc) wherein 50 parts by weight Compound No compound 100 parts by weight of the polyester resin represented by I-1 (trade name VYLON 200, manufactured by Toyobo)
100 parts by weight and a tetrahydrofuran (THF) solvent were kneaded with a mixer for 3 hours to prepare a coating solution, and an aluminum-evaporated polyester film (Al-
A photoreceptor was prepared by coating the film on PET (PET) by a wire bar method so that the film thickness after drying was 20 μm. Example 2 The compound _No. Compound 80 parts by weight of a polycarbonate resin represented by I-2 (tradename Panlite L-122
5: Teijin Chemicals Ltd.) A coating solution prepared by dissolving 100 parts by weight of methylene chloride on an aluminum-evaporated polyester film substrate was applied by a wire bar method, and the film thickness after drying was 20.
A charge transport layer was formed to a thickness of μm. On the thus obtained charge transport layer, titanyl phthalocyanine (TiOPc) pulverized by a ball mill for 150 hours
50 parts by weight, polyester resin (trade name Byron 20)
0: manufactured by Toyobo Co., Ltd.), a coating solution was prepared by kneading with a mixer for 3 hours together with 50 parts by weight of a THF solvent, coating was performed by a wire bar method, and the charge generation layer was dried to a thickness of 1 μm. Formed. Example 3 In Example 2, the following structural formula (II) was used instead of TiOPc.
Using squarylium compound represented by I), optionally in a charge transport material to prepare the compound _No. Implementation instead to the compound represented by I-3 Example 2 Similarly photoreceptor.

[0027]

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Embodiment 4 In the embodiment 2, in place of TiOPc, for example,
With chloro Diane Blue is a bisazo pigment as shown in 7-37543 discloses a charge transport material the compound _No. Implementation instead to the compound represented by II-1 Example 2
A photoreceptor was prepared in the same manner as described above.

The electrophotographic characteristics of the photoreceptor thus obtained were evaluated by using an electrostatic recording paper tester "SP-428" manufactured by Kawaguchi Electric.
It measured using. The surface potential Vs (V) of the photoreceptor is an initial surface potential when the surface of the photoreceptor is positively charged by performing a corona discharge of +6.0 kV for 10 seconds in a dark place, and in a state where the corona discharge is subsequently stopped. The surface potential Vd (V) when kept in a dark place for 2 seconds is measured, and the time (s) until Vd is reduced to half by irradiating the surface of the photoreceptor with 2lx illuminance is determined to obtain a half-attenuated exposure amount E _1/2 (lx · s). Further, the surface potential when white light having an illuminance of 2 lx was irradiated for 10 seconds was defined as a residual potential Vr (V). Examples 1 to
With regard to No. 3, since high sensitivity with long wavelength light can be expected, the electrophotographic characteristics when monochromatic light having a wavelength of 780 nm was used were also measured. That is, measurement is performed in the same manner up to Vd, and then a 1 μW monochromatic light (780 nm) is irradiated instead of white light to obtain a half-attenuated exposure amount (μJ / cm ² ), and this light is irradiated on the surface of the photoreceptor for 10 seconds. Potential Vr
(V) was measured. Table 1 shows the measurement results.

[0030]

[Table 1] As can be seen in Table 1, Examples 1-4 have a half-attenuated exposure,
The residual potential is not inferior, and shows good characteristics even at the surface potential. In Examples 1 to 3, the wavelength is 780 n.
It shows high sensitivity even with long-wavelength light of m, indicating that it can be sufficiently used for a semiconductor laser printer. Example 5 Selenium was applied to a 500 μm-thick aluminum plate.
Vacuum deposition to 5 μm to form a charge generation layer,
o. 100 parts by weight of the compound represented by II-2 and polycarbonate resin (trade name PCZ200: manufactured by Mitsubishi Gas Chemical) 1
A coating solution prepared by dissolving 00 parts by weight in methylene chloride was applied using a wire bar, and a charge transport layer was formed so that the thickness after drying was 20 μm. In this photoreceptor, under white light, Vs = −740 V, Vr = −12 V, E _1/2 =
A good result of 1.0 lx · s was obtained. Example 6 In the same manner as in Example 5, 50 parts by weight of an x-type metal-free phthalocyanine and 50 parts by weight of a vinyl chloride copolymer (trade name: MR-110, manufactured by Zeon Corporation) were kneaded with methylene chloride by a mixer for 3 hours and applied. The solution was prepared and applied on an aluminum support to a thickness of about 1 μm to form a charge generation layer.

Next, 100 parts by weight of the compound represented by Compound No. II-3, 100 parts by weight of a polycarbonate resin (trade name: Panlite L-1250, manufactured by Teijin Chemicals), and 0.1 part by weight of silicone oil were mixed with methylene chloride. Then, the resultant was coated on the charge generation layer to a thickness of about 20 μm to form a charge transport layer. In the photoreceptor thus obtained, under white light, Vs = −715 V, Vr = −20 V, E _1/2 =
A good result of 1.2 lx · s was obtained. Example 7 In Example 6, a bisazo pigment represented by the following structural formula (IV) was used in place of the metal-free phthalocyanine, and the charge transporting substance was replaced with the compound represented by compound No. II-4. Similarly, a photoreceptor was prepared. In the photoreceptor thus obtained, Vs = −722 under white light.
Good results were obtained with V, Vr = −10 V, and E _1/2 = 1.4 lx · s.

[0032]

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Example 8 Compound Nos. I-4 to I-12 and Compound No. II-
Photoreceptors were prepared in the same manner as in Example 4 for each of Nos. 5 to II-12, and the results of measurement using "SP-428" are shown in Table 2. 10-6.0 kV corona discharge in dark place
The exposure was expressed in terms of a half-attenuated exposure amount E _1/2 (lx · s) when white light having an illuminance of ₂ lx was irradiated for 2 seconds.

As shown in Table 2, the compound No. I
The photoreceptors using -4 to I-12 and Compound Nos. II-5 to II-12 as the charge transporting materials also exhibited good half-attenuated exposure E1 _{/ 2} .

[0035]

[Table 2]

[0036]

According to the present invention, since the styryl compound represented by the general formula (I) or (II) is used as a charge transporting substance on a conductive substrate, high charge can be obtained even in positive charge and negative charge. A photosensitive member having high sensitivity and excellent repetition characteristics can be obtained. In addition, a suitable substance can be selected as the charge generating substance according to the type of the exposure light source,
For example, if a phthalocyanine compound, a squarylium compound, or a certain bisazo compound is used, a photoconductor usable for a semiconductor laser printer can be obtained. Further, it is possible to improve the durability by providing a coating layer on the surface as required.

[Brief description of the drawings]

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

FIG. 2 is a sectional view showing a negatively-charged laminated photoconductor according to the embodiment of the present invention;

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

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 conductive substrate 3 charge generating material 4 charge generating layer 5 charge transporting material 6 charge transporting layer 7 coating layer 20 photosensitive layer 21 photosensitive layer 22 photosensitive layer

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G03G 5/06 315

Claims (3)

(57) [Claims] An electrophotographic device comprising a conductive substrate having a photosensitive layer laminated thereon, wherein the photosensitive layer contains at least one styryl compound represented by the following general formula (I) as a charge transporting substance. Photoconductor. Embedded image [Wherein X represents an oxygen atom or a sulfur atom, and R ₁ , R ₂
Represents a hydrogen atom, a substituted or unsubstituted alkyl group, an aryl group or a heterocyclic group, respectively, and Ar ₁ and Ar ₂ represent a substituted or unsubstituted aryl group or a heterocyclic group, respectively. ] 2. An electrophotographic device comprising a conductive substrate having a photosensitive layer laminated thereon, wherein the photosensitive layer contains at least one styryl compound represented by the following general formula (II) as a charge transport material. Photoconductor. Embedded image [Wherein X represents an oxygen atom or a sulfur atom, and R ₃ and R ₄
Represents a hydrogen atom, an alkyl group or a substituted or unsubstituted aryl group, respectively, and Ar ₃ represents a substituted or unsubstituted aryl group or a heterocyclic group. ] 3. The electrophotographic photoconductor according to claim 1, wherein the photoconductive layer is formed by laminating a charge generation layer and a charge transport layer.