JPH01150147A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To enhance photosensitivity of a photosensitive body by incorporating a specified azo compound. CONSTITUTION:The photosensitive layer 2B of the photosensitive body contains as an electric charge generating material at least one of the azo compounds represented by formula I in which each of R1-R4 is H, halogen, alkyl, or the like, and A is a coupler residue. The layer 2B is formed by coating a conductive substrate 1 with a liquid dispersion containing said azo compound, such as a compound of formula II to form an electric charge generating layer 3, and coating the layer 4 with a solution containing a charge transfer material to form a charge transfer layer 6, or reversing the lamination order of the layer 4 and the layer 6, and the photosensitive layer may have a single layer structure.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to an electrophotographic photoreceptor, and particularly to a photosensitive layer formed on a conductive substrate.

[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. Dispersed, Po I
Organic photoconductive substances such as J-N-vinyl carbazole or polyvinyl anthracene, organic photoconductive substances such as phthalocyanine compounds or bisazo compounds dispersed in a resin binder or vacuum-deposited are used. has been done.

The photoreceptor also has the ability to retain surface charge in the dark.

It is necessary to have the function of receiving light and generating charge, and also the function of receiving light and transporting charge, and so-called single-layer photoreceptors that have both of these functions in one layer, There is a so-called laminated photoreceptor in which functionally separated layers are laminated, including a layer that mainly contributes to charge generation, a layer that contributes to surface charge retention in the dark, and a layer that contributes to charge transport during light reception. 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 electrostatic latent images such as letters and pictures on the document by exposing the surface of the charged photoconductor, and This is done by developing a latent image with toner and fixing the developed toner image on a support such as paper. After the toner image is transferred, the photoreceptor is subjected to static neutralization, residual toner removal, photostatic static elimination, etc., and then it is reused. served.

In recent years, electrophotographic photoreceptors using organic materials have been put into practical use due to their advantages such as flexibility, thermal stability, and film-forming properties. For example, poly-N-vinyl carbazole and 2
．． 4.7-)! Photoreceptor consisting of I nitrofluorene-9-one (described in U.S. Pat. No. 3,484,237)
, a photoreceptor whose main component is an organic pigment (Japanese Patent Application Laid-Open No. 47-375
43 (described in Japanese Patent Application Laid-Open No. 1987-10735), and a photoreceptor whose main component is a eutectic complex consisting of a dye and a resin (described in Japanese Patent Application Laid-open No. 10735/1983).

Furthermore, many new azo compounds and perylene compounds have been put into practical use.

[Problems to be Solved by the Invention] As mentioned above, organic materials have many advantages that inorganic materials do not have, but there is no material that fully satisfies all the characteristics required of electrophotographic photoreceptors. The current situation is that we haven't gotten it yet, especially light.

There were problems with sensitivity and characteristics during repeated and continuous use.

The present invention has been made in view of the above-mentioned points, and by using a new organic material that has never been used as a charge generating substance in the photosensitive layer, it can be used in copiers and printers with excellent photosensitivity. The purpose of the present invention is to provide an electrophotographic photoreceptor for use in electrophotography.

[Means for solving problems]

According to the present invention, the above object is achieved by the following formula:
This is achieved by providing a photosensitive layer containing at least one type of azo compound represented by an allyl group, an aryl group, an aralkyl group, a carboxyl group, or an ester group, where A is a coupler residue.

The azo compound of the general formula used in the present invention is synthesized by coupling the corresponding diazonium salt and coupler in a suitable organic solvent such as N,N-dimethylformamide (DMF) by reacting with a base. can do. Specific examples of the azo compound of the general formula thus obtained are as follows.

II II
III II
III II
II2
2 zz
z
zII II
III
II 11? &22
0H, The photoreceptor of the present invention contains an azo compound represented by the above general formula in the photosensitive layer. It can be used as shown in

1 to 3 are conceptual cross-sectional views of the photoreceptor of the present invention.
2A, 2B, and 2C 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 photosensitive layer 2A (commonly referred to as a single-layer photoreceptor) in which an azo compound serving as a charge generating substance 3 and a charge transporting substance 5 are dispersed in a resin binder is provided on a conductive substrate 1. It is something.

FIG. 2 shows a photosensitive layer 2B (usually The structure is called a laminated photoreceptor).

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

The reason for the layer structure shown in FIGS. 2 and 3 is as follows.
The layer structure shown in FIG. 2 is usually used as a negative charging method. Even if an attempt is made to use the layer structure shown in FIG. 2 in a positive charging system, the current situation is that no charge transport material compatible with this has been found. Therefore, as already proposed by the present inventors as a positive charging type photoreceptor, the layer structure shown in FIG. 3 can be used.

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

The photoreceptor shown in Fig. 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 pine or goo, and drying it, and then applying a charge-transporting substance and a resin binder on top of the dispersion. It can be produced by applying a dissolved solution and drying it.

The photoreceptor shown in Figure 3 is a dispersion obtained by coating a solution containing a charge transporting substance and a resin binder on a conductive substrate and drying it, and then dispersing particles of a charge generating substance thereon in a solvent or a resin binder. It can be produced by applying a liquid and drying it.

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 also be made of metal, glass, resin, or the like, which has been subjected to conductive treatment.

The charge generation layer 4 is formed by applying a material in which 30 particles of a charge generation substance made of an azo compound represented by the general formula are dispersed in a resin binder, and generates charges by receiving light. 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 charge is less dependent on the electric field and can be easily injected even in a low electric field. The charge generation layer is mainly composed of a charge generation substance, and a charge transport substance or the like may 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 coating a resin binder with 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 transport substance. 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 a resin binder, polycarbonate, polyester, polyamide,
Polyurethane, epoxy, silicone resin.

Polymers and copolymers of methacrylic acid esters can be used.

The coating layer 7 has the function of receiving and retaining the charge 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. Furthermore, these organic materials can be mixed with inorganic materials such as glass resin and silicon dioxide, 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 silicon dioxide, 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.

[Effect]

There is no known example of using an azo compound represented by the above general formula in a photosensitive layer. In order to achieve the above object, the present inventors conducted a number of experiments on these azo compounds while conducting intensive studies on various organic materials. We have discovered that the use of an azo compound represented by the above general formula as a charge-generating substance in the photosensitive layer of a single-layer or laminated photoreceptor is extremely effective in improving electrophotographic properties, and we have developed an azo compound with excellent photosensitivity. This led to the creation of a photoreceptor.

〔Example〕

Examples of the present invention will be described below.

Example 1 50 parts by weight of the azo compound represented by the compound Nα1,
100 parts by weight of polyester resin and 1-phenyl-5-(
p-diethylaminostyryl)-5-(p-diethylaminophenyl)-2-pyrazoline (ASPP > 100 parts by weight) and a tetrahydrofuran (THF) solvent were kneaded in a mixer for 3 hours to prepare a coating solution, and a conductive substrate was prepared. A photoreceptor was prepared by coating an aluminum vapor-deposited polyester film using a wire bar method to form a photosensitive layer having a thickness of 15 μm after drying.

Example 2 A solution in which 100!1 parts of t'f, p-diethylaminobenzaldehyde-diphenylhydrazone (ABPH) was dissolved in 700 parts by weight of tetrahydrofuran (THF) and 100 parts by weight of polycarbonate resin were mixed in a 1:1 mixed solvent of THE and dichloromethane. A coating solution prepared by mixing 700 parts by weight of the solution was applied onto an aluminum-deposited polyester film substrate using a wire bar method, and the film thickness after drying was 15 μm.
A charge transport layer was formed to have a thickness of m. On the thus obtained charge transport layer, 50 parts by weight of the azo compound represented by the compound Nl11 and 50 parts by weight of the polyester resin were placed.

A coating solution was prepared by kneading 50 parts by weight of PMMA and a THF solvent in a mixer for 3 hours, and coating by wire bar method to form a charge generation layer so that the film thickness after drying was 0.5 μm. The photoreceptor shown in the figure was manufactured.

Example 3 In Example 2, the charge transport material was changed to ABPH,
A charge transport layer was formed in the same manner as in Example 2 using α-phenyl-4°-N,N-dimethylaminostilbene, which is a styryl compound, and a charge generation layer was further formed to prepare a photoreceptor.

Example 4 In Example 2, a charge transport layer was formed in the same manner as in Example 2 using tri(p-tolyl)amine, which is a triphenylamine compound, instead of ABPH as the charge transport substance, and a charge generation layer was further formed. A photoreceptor was prepared.

Example 5 In Example 2, the charge transport material was changed to ABPH,
A charge transport layer was formed using the oxadiazole compound 2,5-bis(p-diethylaminophenyl)-1,3゜4-oxadiazole in the same manner as in Example 2, and a charge generation layer was further formed and photosensitive. The body was created.

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

The surface potential V (volts) of the photoreceptor is +6. OkV
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 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.
The time (seconds) required for V to be halved after irradiation with lux white light was determined and defined as half-attenuation exposure fiE1/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 and 3°4.5 had good half-attenuation exposure and residual potential.

Example 6 Azo compound 1 represented by the above compounds Nα2 to Nα30
A coating solution was prepared by kneading 00 parts by weight of each of these with 1 part by weight of a polyester resin and 1 part by weight of a THF solvent for 3 hours in a mixer, and the coating solution was coated on an aluminum support to a thickness of approximately 0.5 μm to form a charge generation layer. did. On top of this, ASPP obtained by the same method as produced in Example 2
A photoreceptor was prepared by applying a coating liquid having a charge transport layer of about 15 μm.

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 2.

A corona discharge of -6,QkV was applied to the surface of the photoconductor in a dark place for 10 minutes.
The photoreceptor surface was charged negatively for 2 seconds, then held in the dark for 2 seconds with corona discharge stopped, the surface potential (volts) was measured, and the surface of the photoreceptor was then irradiated with white light at an intensity of 2 lux. The time it takes for V to be halved (seconds)
was determined and defined as half-attenuation exposure 'ILE+/x (lux/second). Further, the surface potential when white light with an illumination intensity of 2 lux was irradiated for 10 seconds was defined as the residual potential V (volt). Both half-attenuation exposure and residual potential are good.

Table 2 (Part 1) Table 2 (Part 2) [Effects of the Invention] According to the present invention, since an azo compound represented by the above general formula is used as a charge generating substance on a conductive substrate, positively charged Moreover, an excellent photoreceptor with high sensitivity can be obtained even when negatively charged. Furthermore, if necessary, a coating layer can be provided on the surface to improve durability.

FIG. 2 is a conceptual cross-sectional view showing an example.

DESCRIPTION OF SYMBOLS 1... Conductive substrate, 2A, 2B, 2C... Photosensitive layer, 3...- Charge generating substance, 4... Charge generating layer,
5...-charge transport material, 6...charge transport layer, 7
...Covering layer.

Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] 1) General formula ▲ Numerical formula, chemical formula, table, etc. group, aralkyl group, carboxyl group or ester group, A is a coupler residue)
1. A photoreceptor for electrophotography, comprising a photosensitive layer containing at least one type of azo compound represented by: