JP2868838B2 - Electrophotographic photoreceptor - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an electrophotographic photoreceptor, and more particularly, to a photosensitive layer formed on a conductive substrate, wherein a bisazo compound represented by the general formula (I) is contained in a photosensitive layer. The present invention relates to an electrophotographic photoreceptor characterized by containing.

[Conventional technology]

2. Description of the Related Art Photoreceptors for electrophotography (hereinafter also referred to as photoreceptors) are generally widely used in copiers, printers, and the like, and various materials have been studied and put into practical use since the invention of the Carlson method. For example, a photoreceptor using an inorganic photoconductive substance such as selenium, zinc oxide, and cadmium sulfide is well known. This photoreceptor has excellent light sensitivity, but has problems in moisture resistance and durability. , Selenium and cadmium sulfide have the disadvantage of being toxic. On the other hand, a photoreceptor using an organic photoconductive substance can separate functions into a charge generation material that generates charges by light irradiation and a charge transport material that transports the charges, so that any material can be easily obtained. In recent years, many photoconductors using organic materials have been proposed because they are inexpensive and excellent in hygiene, and have advantages such as flexibility, thermal stability, and film forming property. Particularly, the photoconductive organic compound having excellent charge generating ability is described in, for example, phthalocyanine described in U.S. Pat.No. 3,816,118, anthranthrone described in JP-B-60-60052, and JP-B-61-29496. The squarylium,
Azurenium and the like described in JP-A-59-133553 have been put to practical use.

[Problems to be solved by the invention]

As described above, organic materials have many advantages over inorganic materials, but at the same time, at the same time, those that sufficiently satisfy all the characteristics required for electrophotographic photoreceptors have not yet been obtained. In particular, there was a problem in light sensitivity and characteristics in repeated continuous use.

The present invention has been made in view of the above points, and has a red reproducibility and a high sensitivity by using a new organic material which has not been used as a charge generating material in the photosensitive layer. An object of the present invention is to provide an electrophotographic photoreceptor having excellent repetition characteristics and durability.

[Means for solving the problem]

According to the present invention, the above object is attained by providing an electrophotographic photosensitive member including a photosensitive layer containing at least one of the bisazo compounds represented by the following general formula (I).

As A (coupler residue) in the above general formula, one represented by the following general formulas (II) to (VII) is preferably used.

[In the formulas (II) to (VII), Z represents any one of residues that are condensed with a benzene ring to form an aromatic polycyclic or heterocyclic ring, and X ₁ represents a hydrogen atom, COOR ₁ , CONR ₂ R
₃ (R ₁ , R ₂ and R each represent a hydrogen atom, any of the following optionally substituted alkyl groups, aryl groups, and heterocyclic groups), and X ₂
And X ₅ each represents an alkyl group, an aryl group, or a heterocyclic group which may be substituted, and X ₃ and X ₆
It is a hydrogen atom, a cyano group, a carbamoyl group, a carboxyl group, an ester group, any of acyl group, X ₄
And X ₁₁ represent a hydrogen atom, any of the following alkyl groups, cycloalkyl groups, alkenyl groups, aralkyl groups, aryl groups and heterocyclic groups which may be substituted, and X ₇ and X ₈ represent a hydrogen atom , Halogen atom, nitro group,
X ₉ represents any of the following optionally substituted alkyl, aryl, carboxyl, and ester groups, and X ₉ represents any of the following optionally substituted alkyl, aryl, carboxyl, and ester groups: , X ₁₀ following each optionally substituted aryl group, any of the heterocyclic group, Y represents a residue forming an aromatic heterocyclic ring. The bisazo compound represented by the general formula (I) is obtained by subjecting a corresponding diamino compound to tetrazotization by a conventional method, and then using a corresponding coupler and a suitable solvent (for example, N, N dimethylformamide, dimethyl sulfoxide, etc.) in the presence of an alkali. ) Can be easily synthesized.

The diamino compound used in this reaction can be synthesized by the method described in Oshima, Mokai, Fukui-Daikokuho 16,237 (1968).

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

[Action] There is no known example of using the bisazo compound represented by the general formula (I) in a photosensitive layer. The present inventors have conducted intensive studies on various organic materials in order to solve the above-described problems, and as a result of conducting a number of experiments on these azo compounds, the technical elucidation has not been sufficiently performed.
It has been found that the use of such a specific bisazo compound represented by the general formula (I) as a charge generating substance is extremely effective for improving electrophotographic properties. As a result, a photoreceptor having red reproducibility, high sensitivity, excellent repetition characteristics and durability, and excellent pigment dispersibility was obtained.

〔Example〕

The photoreceptor of the present invention contains the compound represented by the above general formula (I) in the photosensitive layer. Depending on how these compounds are applied, the photoreceptor shown in FIG. 1, FIG. 2 or FIG. Can be used as if.

1 to 3 are conceptual cross-sectional views of a photoreceptor of the present invention, wherein 1 is a conductive substrate, 20, 21, and 22 are photosensitive layers, 3 is a charge generating material, 4 is a charge generating layer, and 5 is a charge generating layer. A transport material, 6 is a charge transport layer, and 7 is a coating layer.

FIG. 1 shows a photosensitive layer 20 (usually referred to as a single-layer type photoreceptor) in which a compound of the general formula (I), which is a charge generating substance 3, and a charge transporting substance 5 are dispersed in a resin binder on a conductive substrate 1. Configuration) is provided.

FIG. 2 shows a laminate of a charge generation layer 4 containing a compound of the general formula (I), which is a charge generation substance 3, on a conductive substrate 1 and a charge transport layer 6 mainly composed of a charge transport substance 5. (Usually referred to as a laminated photoconductor).

FIG. 3 shows a case where a photosensitive layer 22 having a layer structure opposite to that of FIG. 2 is provided. In this case, it is general to further provide a coating layer 7 to protect the charge generation layer 4.

The reason why the two-layer structure shown in FIGS. 2 and 3 is adopted as the laminated photoreceptor is that even if an attempt is made to use the layer structure shown in FIG. No charge transport material has been found, and therefore, the layer configuration shown in FIG. 3 is required at this stage as a positively charged photosensitive member.

The photoreceptor shown in FIG. 1 can be produced 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 of FIG. 2, a dispersion obtained by dispersing particles of a charge generating substance in a solvent or a resin binder on a conductive substrate was applied and dried, and the charge transporting substance and the resin binder were dissolved thereon. It can be produced by applying and drying a solution.

The photoreceptor shown in FIG. 3 is obtained by applying a solution in which a charge transporting substance and a resin binder are dissolved on a conductive substrate, drying the solution, and then dispersing the particles of the charge generating substance in a solvent or a resin binder. It can be produced by applying a liquid, drying and further forming a coating layer.

The conductive substrate 1 serves as an electrode of the photoreceptor and also serves as a support for the other layers, and may be cylindrical, plate-like, film-like, or made of aluminum, stainless steel, nickel, or the like. A conductive material may be applied to the above-mentioned metal, glass, resin, or the like.

The charge generation layer 4 is formed by applying a material in which particles of the charge generation material 3 represented by the compound represented by the general formula (I) are dispersed in a resin binder, and generates light by receiving light. In addition, the charge generation efficiency is high, and at the same time, the injected property of the generated charge into the charge transport layer 6 and the coating layer 7 is important. 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, vinyl chloride, epoxy, silicone resin, diallyl phthalate resin, butyral resin, methacrylic acid ester polymer and copolymer can be used in appropriate combination. As a solvent for dispersing the resin binder, ethyl acetate, methyl ethyl ketone, tetrahydrofuran, dichloromethane, dichloroethane, N, N dimethylformamide, and the like can be used. The ratio of dispersing the charge generating material in the resin binder is 5% to 95%, preferably 50%.
~ 85%.

The charge transport layer 6 is formed by applying a material in which a hydrazone compound, a pyrazoline compound, a stilbene compound, a triphenylamine compound, an oxazole compound, an oxadiazole compound, or the like is dissolved and dispersed as an organic charge transport material in a resin binder. In a dark place, the layer functions as an insulator layer to retain the charge of the photoreceptor, and at the time of receiving light, functions to transport the charge injected from the charge generation layer. Polymers and copolymers of polycarbonate, polyester, and methacrylate can be used as the resin binder.

The coating layer 7 has a function of receiving and holding the charge of the corona discharge in a dark place, and has a performance of transmitting light which the charge generation layer responds to. It is necessary to neutralize and eliminate the surface charge by receiving 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 can be used in combination with an inorganic material such as glass resin and SiO ₂ , a metal alkoxy compound having a film forming ability, and further a material such as a metal or a metal oxide which reduces electric resistance. The coating material is not limited to organic insulating film forming material, but is
It is also possible to form an inorganic material such as O ₂ , a metal, a metal oxide or the like by a method such as vapor deposition 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 composition of the coating layer, it can be set arbitrarily within a range where adverse effects such as an increase in residual potential do not occur when repeatedly used continuously.

 Hereinafter, embodiments of the present invention will be described.

Example 1 10 parts by weight of the compound represented by the compound No. 1 was mixed with 100 parts by weight of a polyester resin (trade name: Byron 200: manufactured by Toyobo) and 1-phenyl-3- (p-diethylaminostyryl)-
100 parts by weight of 5- (p-diethylaminophenyl) -2-pyrazoline (ASPP) and a solvent of tetrahydrofuran (THF) were kneaded with a mixer for 3 hours to prepare a coating solution, and an aluminum-evaporated polyester film (Al −
PET) on a wire bar method, and the film thickness after drying is 1
A photosensitive layer having a thickness of 5 μm was formed, and a photosensitive member having the structure shown in FIG. 1 was prepared.

Example 2 First, 100 parts by weight of P-diethylaminobenzaldehyde-diphenylhydrazone (ABPH) and 100 parts by weight of a polycarbonate resin (trade name: Panlite L-1250: manufactured by Teijin Chemicals Co., Ltd.) were dissolved in methylene chloride to deposit a coating liquid on aluminum. It was applied on a polyester film substrate by a wire bar method, and a charge transport layer was formed so that the film thickness after drying was 15 μm. On the thus obtained charge transport layer, the compound
A coating liquid was prepared by kneading 50 parts by weight of the compound represented by No. I-2 with 50 parts by weight of a polyester resin (trade name: Byron 200: manufactured by Toyobo) and a THF solvent by a mixer for 3 hours.
A photoreceptor having the configuration shown in FIG. 3 was prepared by applying a wire bar method, forming a charge generation layer such that the film thickness after drying became 0.5 μm, and further forming a coating layer thereon.

Example 3 A photoconductor was prepared by the same way as that of Example 2 except that the charge transporting substance, ABPH, was changed to α-phenyl-4′-N, N-dimethylaminostilbene, which is a stilbene compound.

Example 4 A photoconductor was prepared by the same way as that of Example 2 except that the charge transport material ABPH was changed to tri (p-tolyl) amine, which was a triphenylamine compound.

Example 5 In Example 2, the charge transport material ABPH was changed to 2,5-bis (p-diethylaminophenyl) -1,3,4-oxadiazole, which is an oxadiazole compound. A photoreceptor was produced in the same manner as described above.

The electrophotographic characteristics of the photoreceptor thus obtained were measured using an electrostatic recording paper tester “SP-428” manufactured by Kawaguchi Electric. Table 1 shows the results.

The photoconductor surface potential V _s (volts) is the initial surface potential when the photoconductor surface is positively charged by performing +6.0 kV corona discharge in a dark place for 10 seconds, and then the corona discharge is stopped. Surface potential V _d (volts) when kept in the dark for 2 seconds at
And then irradiating the surface of the photoreceptor with white light having an illuminance of 2 lux to determine a time (second) until _Vd is reduced to half, thereby obtaining a half-attenuated exposure amount E _1/2 (lux second). . Also,
The surface potential when white light having an illuminance of 2 lux was irradiated for 10 seconds was defined as a residual potential V _r (volt).

As can be seen from Table 1, Examples 1 to 5 had good half-attenuated exposure and residual potential.

Example 6 100 parts by weight of the compounds represented by the compounds No. 3 to No. 66 were kneaded with 100 parts by weight of a polyester resin (trade name: Byron 200, manufactured by Toyobo Co., Ltd.) and a THF solvent by a mixer for 3 hours to prepare a coating solution. Prepared, about 0.5 on aluminum support
It was applied to a thickness of μm to form charge generation layers. On this, an ABPH coating solution obtained by the same method as that prepared in Example 2 was applied to a thickness of about 15 μm to form a charge transport layer, and a photoreceptor having the structure shown in FIG. 2 was obtained. Produced.

The electrophotographic characteristics of the photoreceptor thus obtained were measured using Kawaguchi Denki's electrostatic recording paper tester "SP-428", the corona discharge voltage was changed to -6.0 kV, and the others were as in Examples 1 to 5. The measurement was performed in the same manner as described above. Table 2 shows the results.

As can be seen from Table 2, the photoreceptors using the above-mentioned compounds No. 3 to No. 66 as the charge generating materials also exhibited good half-attenuation exposure amounts E1 _{/ 2} .

〔The invention's effect〕

According to the present invention, the compound represented by the general formula (I) is used as the charge generating substance in the photosensitive layer formed on the conductive substrate, so that the red reproducibility is good, and the positive charge and the negative charge are high. It is possible to obtain a good photoreceptor excellent in sensitivity and repetition characteristics and without image unevenness. Further, it is possible to improve durability by providing a coating layer on the surface as needed.

[Brief description of the drawings]

FIGS. 1, 2 and 3 are conceptual sectional views showing different embodiments of the photoreceptor of the present invention. 1: conductive substrate, 3: charge generation material, 4: charge generation layer, 5: charge transport material, 6: charge transport layer, 7: coating layer, 20, 21, 22: photosensitive layer.

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Noboru Furusho 1-1-1, Tanabe-Nitta, Kawasaki-ku, Kawasaki-shi, Kanagawa Prefecture Inside Fuji Electric Co., Ltd. (72) Koichi Hasebe 4--10 Nakai, Kokurakita-ku, Kitakyushu-shi, Fukuoka Prefecture ― 3 (72) Inventor Hiroshi Miyazaki 2--4-4-2 Nakai, Kokurakita-ku, Kitakyushu-shi, Fukuoka (72) Inventor Masafumi Furumoto 2- 13-3 Nakai, Kokurakita-ku, Kitakyushu-shi, Fukuoka (56) References JP-A-54-21728 (JP, A) JP-A-64-21456 (JP, A) JP-A-3-37657 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) G03G5 / 00-5/16

Claims (2)

(57) [Claims] 1. An electrophotographic photosensitive member comprising a photosensitive layer containing at least one of the bisazo compounds represented by the following general formula (I). [In (I), A represents a coupler residue. ] 2. The photoreceptor according to claim 1, wherein A (coupler residue) in the general formula (I) is represented by the following general formulas (II to VII): Photoreceptor. [In the formulas (II to VII), Z represents any of residues that are condensed with a benzene ring to form an aromatic polycyclic or heterocyclic ring, and X ₁ represents a hydrogen atom, COOR ₁ , CONR ₂ R ₃ (Wherein R ₁ , R ₂ and R ₃ each represent a hydrogen atom, an alkyl group, an aryl group or a heterocyclic group which may be substituted each of the following), and X ₂ And X ₅ each represents an optionally substituted alkyl group, an aryl group, or a heterocyclic group; X ₃ and X ₆ represent a hydrogen atom;
Represents any of a cyano group, a carbamoyl group, a carboxyl group, an ester group, and an acyl group, and X ₄ and X ₁₁ are a hydrogen atom, an alkyl group, a cycloalkyl group, an alkenyl group, an aralkyl Base,
X ₇ and X ₈ represent any of a hydrogen atom, a halogen atom, a nitro group, an alkyl group optionally substituted below, and an alkoxy group, X ₉ represents any of the following optionally substituted alkyl groups, aryl groups, carboxyl groups, and ester groups, and X ₁₀ represents the following optionally substituted aryl groups and heterocyclic groups: Y represents a residue forming an aromatic heterocyclic ring. ]