JPS63158563A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To obtain a photosensitive body high in sensitivity and superior in characteristics resisting to repeated uses by using a specified azo compound as an electric charge generating material. CONSTITUTION:The photosensitive layer contains as the charge generating material at least one of the azo compounds containing bithiophene structure represented by formulae I and II in which each of R1-R10 is H, halogen atom, OH, alkyl, alkoxy, allyl, aldehyde, acyl, carboxy, ester, carbamoyl, amino, alkylamino, arylamino, aryl, aralkyl, nitro, or cyano group; and N=N-A1 is an azo residue, and N=N-A2-N=N is a disazo residue, thus permitting the obtained photosensitive body to be high in sensitivity even in the case of positive and negative charging, and superior in repeated use characteristics.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an electrophotographic photoreceptor, and more specifically, in a photosensitive layer formed on a conductive substrate, compounds of the general formulas (I)i and (II) are incorporated. ) The present invention relates to an electrophotographic photoreceptor characterized by containing an azo compound represented by the following.

[Conventional technology]

Conventionally, photosensitive materials for electrophotographic photoreceptors (hereinafter also referred to as photoreceptors) include inorganic photoconductive substances such as selenium or selenium alloys, or inorganic photoconductive substances such as zinc oxide or cadmium sulfide in a resin binder. dispersion, organic photoconductive materials such as poly-N-vinyl carbazole or polyvinyl anthracene, organic photoconductive materials such as phthalocyanine compounds or bisazo compounds, or dispersion of these photoconductive materials in a resin binder. Those that have been made are used.

In addition, a photoreceptor must have the function of retaining surface charge in the dark, the function of receiving light and generating charge, and the function of receiving light and transporting charge, but these functions can be achieved in one layer. A so-called single-layer type photoreceptor that has both functions, and a so-called laminated type that has two functionally separated layers: a layer that mainly contributes to charge generation, a layer that contributes to surface charge in the dark, and a layer that contributes to charge transport during light reception. There is a photoreceptor. For example, the Carlson method is applied to image formation by electrophotography using these photoreceptors. Image formation in this method involves charging the photoconductor in a dark place by corona discharge, forming an electrostatic latent image such as text or pictures on the original on the surface of the charged photoconductor, and forming an electrostatic latent image on the surface of the charged photoconductor. After the toner image has been transferred, the photoreceptor is subjected to static electricity removal, removal of residual toner, photostatic static removal, etc. before being reused. be done.

In recent years, due to its advantages such as flexibility, thermal stability, and film-forming properties,
Electrophotographic photoreceptors using organic materials are being put into practical use. For example, Po'JN-vinylcarbazole and 2.
4.7-)! j nitrofluoren-9-one (described in US Pat. No. 3,484,237),
Photoreceptor containing organic pigment as main component (Japanese Patent Application Laid-Open No. 47-3754
3), and a photoreceptor whose main component is a eutectic complex consisting of a dye and a resin (described in JP-A-47-10735). Furthermore, many new hydrazone compounds have also been put into practical use.

[Problem that the invention seeks to solve]

However, although organic materials have many advantages that inorganic materials do not have, it is currently not possible to obtain a material that satisfactorily satisfies all the characteristics required of an electrophotographic photoreceptor, especially in terms of photosensitivity and There were problems with the characteristics when used repeatedly and continuously.

The present invention has been made in view of the above points, and by using a new organic material that has never been used as a charge generating substance in the photosensitive layer, electrophotography with high sensitivity and excellent repeatability can be achieved. The purpose of the present invention is to provide a photoreceptor for use.

[Means for solving problems]

In order to achieve the above object, the present invention provides an electrophotographic photosensitive layer having a photosensitive layer containing at least one kind of azo compounds containing a bithiophene structure represented by the following general formula (I) or (II). body.

(In formulas (I) and (II), R1, R2, R3, R4
゜Rs, Rs, R7, Ra, Ra and R
3° is a hydrogen atom, a halogen atom, a hydroquine group, an alkyl group, an alkoxy group, an allyl group, and an aldehyde group, respectively.

Acyl group, carboxyl group, ester group, carbamoyl group, amino group, alkylamino group, arylamino group,
represents an aryl group, an aralkyl group, a nitro group or an ano group, N=N-A, represents an azo residue, N=N-A
2-N=N represents a disazo residue. ) [Function] There is no known example of using an azo compound represented by the above general formula (I) or (If) in a photosensitive layer. The inventors
While conducting intensive studies on various organic materials to achieve the above objective, we conducted numerous experiments on these azo compounds, and found that although their technical clarification has not yet been fully elucidated, the general formula ( I) or (It
It was discovered that the use of a specific azo compound shown in ) as a charge-generating substance is extremely effective in improving electrophotographic properties, and a photoreceptor with high sensitivity and excellent repeatability was obtained.

〔Example〕

The azo compounds of the general formulas (I) and (II) used in the present invention can be obtained by reacting the corresponding diazonium salts and couplers with a base in an appropriate organic solvent such as N,N-dimethylformamide (DMF). , can be synthesized by coupling reaction.

Specific examples of the azo compounds of the general formulas (I) and (II) thus obtained are as follows.

)+zNcOff-N OCH3N(Ll 1H2N-
f'; υ N-NC and CI Nα12QcHz4+
i-+y()-ci Nα1602ullυ>N
-N-(I)-0CH3Nα17N, gN-NQo+t
No, 18C1υΔN-NCdiONα19 H3 (J'T%JA state ■Nα20 The photoreceptor of the present invention contains an azo compound represented by the above general formulas (I) and (II) in the photosensitive layer. However, depending on the application of these azo compounds, they can be used as shown in FIG. 1, FIG. 2, or FIG. 3.

1st vf! 3 are conceptual cross-sectional views of different embodiments of the photoreceptor of the present invention, in which 1 is a conductive substrate, 20, 2 are
1.22 is a photosensitive layer, 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 an azo compound as a charge-generating substance 3 and a charge-transporting substance 5 on a conductive substrate 1 using a resin binder (binder).
A photosensitive layer 20 (commonly referred to as a single-layer photoreceptor) is provided therein.

FIG. 2 shows a photosensitive layer 21 consisting of a conductive substrate 1 and a charge generating layer 4 containing an azo compound as a charge generating substance 3, and a charge transporting layer 6 mainly containing a charge transporting substance 5.
The structure is usually referred to as a laminated photoreceptor).

FIG. 3 shows an inverse layer configuration to that in FIG.

In this case, a covering layer 7 is generally provided to protect the charge generation layer 4.

The reason for the two types of layer configurations shown in FIGS. 2 and 3 is that the photoreceptor is used in a positive charging system or a negative charging system, and the layer configuration shown in FIG. 2 is usually used in a negative charging system. Even if you try to use the positive charging method with the layer configuration shown in Figure 2,
At present, no charge-transporting substance has been found that meets this requirement. Therefore, as the present inventors have already proposed, the layer structure shown in Figure 3 is considered to be effective as a positive charging type photoreceptor. It can be mentioned.

The photoreceptor shown in FIG. 1 can be produced by dispersing a charge generating substance in a solution containing a charge transporting substance and a resin binder, and applying this dispersion onto a conductive substrate.

The photoreceptor shown in Figure 2 is produced by coating a conductive substrate with a dispersion obtained by dispersing particles of a charge-generating substance in a solvent or resin binder, and drying the dispersion, and dissolving a charge-transporting substance and a resin binder thereon. It can be produced by applying a solution and drying it.

The photoreceptor shown in Figure 3 was obtained by coating a conductive substrate with a solution containing a charge generating substance and a resin binder and drying it, and then dispersing particles of the charge generating substance in a solvent or a resin binder. It can be produced by applying a dispersion liquid, drying it, and further forming a coating layer 7.

The conductive substrate 1 serves as an electrode for the photoreceptor and at the same time serves as a support for the other layers, and may be cylindrical, plate-shaped, or film-shaped, and may be made of aluminum, stainless steel, nickel, etc. It may be made of metal, glass, resin, or the like and subjected to 4TL treatment.

The charge generation layer 4 is formed by applying a material in which particles of the charge generation substance 3 made of an azo compound represented by the general formulas (I) and (II) are dispersed in a resin binder.
It receives light and generates an electric charge. In addition to the high charge generation efficiency, the ability to inject the generated charges into the charge transport layer 6 and the coating layer 7 is also important, and it is desirable that the electric field value σ is small and the injection is good even at a low electric field. The charge generation layer is mainly composed of a charge generation substance, and a charge transporting substance can also be added thereto. As the resin binder, polycarbonate, polyester, polyamide, polyurethane, epoxy, silicone resin, polymers and copolymers of methacrylic acid ester, etc. can be used in appropriate combinations.

The charge transport layer 6 is formed by applying a material in which a hydrazone compound, a pyrazoline compound, a styryl compound, a triphenylamine compound, an oxazole compound, an oxadiazole compound, etc. are dissolved and dispersed as an organic charge transporting substance in a resin binder. In the dark, it functions as an insulating layer to hold the charge on the photoreceptor, and when receiving light, it functions to transport the charge injected from the charge generation layer. As the resin binder, polycarbonate, polyester, polyamide, polyurethane, epoxy, silicone resin, polymers and copolymers of methacrylic acid ester, etc. can be used.

The coating layer 7 has the function of receiving and retaining the charges of corona discharge in a dark place, and has the ability to transmit the light to which the charge generation layer is sensitive, and transmits the light upon exposure, and the charge generation layer It is necessary for the surface charge to be neutralized and annihilated by the injection of the generated charge. As the coating material, organic insulating film-forming materials such as polyester and polyamide can be used. In addition, these organic materials, glass resin, Si
It is also possible to use a mixture of inorganic materials such as O□ and materials that reduce electrical resistance such as metals and metal oxides. The coating material is not limited to organic insulating film-forming materials, and may also be formed of inorganic materials such as Si, metals, metal oxides, etc. by methods such as vapor deposition and sputtering. As mentioned above, it is desirable that the coating material be as transparent as possible in the wavelength region where the charge generating substance absorbs maximum light.

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

Hereinafter, specific examples of the present invention will be described.

Example 1 50 parts by weight of the azo compound represented by the compound Nα1 was mixed with 100 parts by weight of polyester resin (Vylon: manufactured by Toyobo Co., Ltd.) and 1-phenyl-3-(P-diethylaminostyryl)-
100 parts by weight of 5-(paradiethylaminophenyl)-2-pyrazoline (ASPP) and tetrahydrofuran (TH
F) Prepare a coating solution by kneading with a solvent in a mixer for 3 hours, and apply it on an aluminum-deposited polyester film (81-PET), which is a conductive substrate, using a wire bar method to determine the film thickness after drying. A photoreceptor was prepared by forming a photosensitive layer so that the thickness of the photoreceptor was 15 μm.

Example 2 First, a solution in which 100 parts by weight of P-diethylaminobenzaldehyde-diphenylhydrazone (ABPH) was dissolved in 700 parts by weight of tetrahydrofuran (T'HF) and a polycarbonate resin (Panlite L-1250) 100 parts by weight
[7 parts of a 1:1 mixed solvent of THF and dichloromethane]
A coating solution prepared by mixing the solution dissolved in the 00 M storage section was applied onto an aluminum vapor-deposited polyester film substrate using a wire bar to form a charge transport layer so that the film thickness after drying was 15 μm.

The compound Nα is placed on the charge transport layer thus obtained.
50 parts by weight of the azo compound represented by 1, 50 parts by weight of polyester resin (trade name Byron 200: manufactured by Toyobo), PM
A photoreceptor was prepared by kneading 50 parts by weight of MA and a THF solvent in a mixer for 3 hours to prepare a coating solution and applying it with a wire bar to form a charge generation layer so that the film thickness after drying was 0.5 μm. did.

Example 3 In Example 2, the charge transport substance was replaced with ABPH, and a styryl compound α-phenyl-4'-N,
A charge transport layer was formed using N-dimethylaminostilbene in the same manner as in Example 2, and a charge generation layer was further formed to produce a photoreceptor.

Example 4 In Example 2, the charge transporting substance was changed to 8BPH, and the charge transport substance was replaced with a triphenylamine compound, )IJ(p-).
A charge transport layer was formed in the same manner as in Example 2 using Rylamine, and a charge generation layer was further formed to produce a photoreceptor.

Example 5 In Example 2, the charge transporting substance was replaced with 8BPH and an oxadiazole compound, 2°5-bis(p
-diethylaminophenyl)-1°3.4-oxadiazole to form a charge transport layer in the same manner as in Example 2,
Furthermore, a charge generation layer was formed to produce a photoreceptor.

The electrophotographic properties of the photoreceptor thus obtained were measured using an electrostatic recording paper tester RSP-428J manufactured by Kawaguchi Electric. The results are shown in Table 1.

The surface potential VS (volt) of the photoreceptor is +6.0kV in the dark.
This is the initial surface potential when corona discharge is performed for 10 seconds to positively charge the surface of the photoreceptor, and the surface potential when the photoconductor surface is then held in the dark for 2 seconds with corona discharge stopped is v,
(volts), and then the illuminance 2 on the photoreceptor surface.
The time (seconds) required for Vd to be halved after irradiation with lux white light was determined as the half-attenuation exposure amount E+/z (lux seconds). Further, the surface potential when white light with an illuminance of 2 lux was irradiated for 10 seconds was defined as the residual potential V (volt).

As seen in Table 1, Examples 1.2.3.4.5 had good half-attenuation exposure and residual potential.

Example 6 Azo compound 1 represented by the above compounds Nα2 to Na89
00 parts by weight of each polyester resin (trade name: Vylon 200) and 100 parts by weight of THF solvent were kneaded in a mixer for 3 hours to prepare a coating solution, which was coated on an aluminum support to a thickness of about 0.5 μm and charged. A generation layer was formed respectively. On top of this, an ASPP coating solution obtained in the same manner as in Example 2 was applied to a thickness of about 15 μm to produce a photoreceptor.

The electrophotographic properties of the photoreceptor thus obtained were measured using an electrostatic recording paper tester R SP-428J manufactured by Kawaguchi Electric. The results are shown in Table 2.

The surface potential v, (volt) of the photoreceptor is -6, OkV in the dark.
This is the initial surface potential when corona discharge is performed for 10 seconds to negatively charge the surface of the photoreceptor, and the surface potential V is the surface potential when the photoreceptor surface is then held in the dark for 2 seconds with corona discharge stopped.
(volts), and then the illuminance 2 on the photoreceptor surface.
Calculate the time (seconds) it takes for V to be halved after irradiating the lux white light and perform half-attenuation exposure ff1E1. It was set as 'a (looks/second). Further, the surface potential when white light with an illuminance of 2 lux was irradiated for 10 seconds was defined as the residual potential V (volt).

As seen in Table 2, these compounds N112~Nα
The photoreceptor using No. 89 also had good half-attenuation exposure and residual potential.

Table 2 (Part 1) Table 2 (Part 2) Table 2 (Part 3) Table 2 (Part 4) Table 2 (Part 5) Table 2 (Part 6) [Effects of the invention] In the present invention According to the above, since the azo compounds represented by the general formulas (I) and (II) are used as charge generating substances in the photosensitive layer provided on the conductive substrate, the photosensitive layer is highly sensitive to both positive and negative charges. A photoreceptor with excellent repeatability can be obtained.

Furthermore, if necessary, it is possible to provide a coating layer on the surface to improve durability.

[Brief explanation of the drawing]

1.2 and 3 are conceptual sectional views showing different embodiments of the photoreceptor of the present invention. 1 Conductive substrate, 3 Charge generating substance, 4 Charge generating layer, 5 Charge transporting substance, 6 Charge transporting layer, 7 Covering layer,
20.21.22 Photosensitive layer.

Claims (1)

[Scope of Claims] 1) An electrophotographic photoreceptor having a photosensitive layer containing at least one kind of azo compounds containing a bithiophene structure represented by the following general formula (I) or (II). . ▲There are mathematical formulas, chemical formulas, tables, etc.▼...(I) ▲There are mathematical formulas, chemical formulas, tables, etc.▼...(II) (In formulas (I) and (II), R_1, R_2, R_3
, R_4, R_5, R_6, R_7, R_8, R_9 and R_1_0 are a hydrogen atom, a halogen atom,
Hydroxy group, alkyl group, alkoxy group, allyl group,
Represents an aldehyde group, acyl group, carboxyl group, ester group, carbamoyl group, amino group, alkylamino group, arylamino group, aryl group, aralkyl group, nitro group, or cyano group, and N=N-A_1 represents an azo residue. where N=N-A_2-N=N represents a disazo residue. )