JPS63287957A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To obtain a sensitive body having high sensitivity and superior repetitive characteristics by incorporating a specified trisazo compd. as an electric charge generating substance into a photosensitive layer on an electrically conductive substrate. CONSTITUTION:A trisazo compd. represented by the formula as an electric charge generating substance 3 is incorporated into a photosensitive layer 20 on an electrically conductive substrate 1. The layer 20 is formed by dispersing the compd. and an electric charge transferring substance 5 in a resin binder. In the formula, each of R1-R7 is H, halogen, hydroxy, alkyl, alkoxy, allyl or the like and Ar is an arom. ring or an arom. heterocyclic group. Since the trisazo compd. is used, a sensitive body having high sensitivity whether positively or negatively charged and also having superior repetitive characteristics can be obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an electrophotographic photoreceptor, and more specifically, the present invention relates to an electrophotographic photoreceptor, and more specifically, a trisazo compound represented by the general formula (1) is incorporated into a photosensitive layer formed on a conductive substrate. The present invention relates to an electrophotographic photoreceptor characterized by containing a compound.

[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-vinylcarbazole or polyvinylanthracene, organic photoconductive materials such as phthalocyanine compounds or bisazo compounds, or dispersion of these organic photoconductive materials in a resin binder. Those that have been made are used.

In addition, a photoreceptor must have the function of retaining a surface charge in the dark, the function of receiving light and generating a charge, and the same function (the function of receiving light and transporting a charge). A so-called single-layer photoreceptor that combines these functions is laminated with functionally separated layers: a layer that primarily contributes to charge generation, and a layer that contributes to surface charge retention in the dark and charge transport during light reception. There are so-called laminated type photoreceptors. For example, the Carlson method is applied to electrophotographic image formation using these photoreceptors. Image formation in this method involves corona discharge to the photoreceptor in a dark place. electrification, formation of an electrostatic latent image such as text or pictures on a document by exposure to light on the surface of the charged photoreceptor, development of the formed electrostatic latent image with toner, and support of the developed toner image on paper, etc. After the toner image has been transferred, the photoreceptor is charged with static electricity, residual toner is removed,
After photostatic charge removal, etc., it is reused.

In recent years, electrophotographic photoreceptors using organic materials have been put into practical use due to their advantages such as flexibility, thermal stability, and ll1j formation. For example, a photoreceptor consisting of poIJ N-vinylcarbazole and 2,4,7-dolinitrofluoren-9-one (described in US Pat. No. 3,484,237), a photoreceptor containing an organic pigment as a main component ( Japanese Unexamined Patent Publication 1973-
37543), and JP-A-47-10735 (a), which describes a photoreceptor whose main component is a eutectic complex consisting of a dye and a resin. Furthermore, many new hydrazone compounds have also been put into practical use.

[Problem that the invention seeks to solve]

As mentioned above, organic materials have many advantages that inorganic materials do not have, but at present, no material has yet been obtained that fully satisfies all the characteristics required of electrophotographic photoreceptors. In particular, there were problems with photosensitivity and characteristics during repeated and continuous use.

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 photoreceptor having a photosensitive layer containing at least one trisazo compound having a terthiophene structure represented by the following general formula (H).

(I) (In formula (1), R+, Rt, Rs, R+, Rs
, Ra and R7 are each a hydrogen atom, a halogen atom, a hydroxy group, an alkyl group, an alkoxy group, an allyl group, an aldehyde group, an acyl group, or a carboxyl group.

Ester group, carbamoyl group, ami7 group, alkylamino group, arylamino group, aryl group, aralkyl group,
represents a nitro group or a cyano group, and A represents a substituted or unsubstituted aromatic ring or aromatic heterocyclic group. The present inventors conducted numerous experiments on these trisazo compounds while conducting intensive studies on various organic materials to achieve the above objective, and found that the technical elucidation of these compounds has not yet been sufficiently elucidated. However, it has been discovered that the use of a specific trisazo compound represented by the above general formula (1) as a charge generating substance is extremely effective in improving electrophotographic properties, and it has been found that the use of a specific trisazo compound represented by the above general formula (1) is extremely effective in improving electrophotographic properties. This led to the creation of an excellent photoreceptor.

〔Example〕

The trisazo compound of the general formula (+) used in the present invention has a corresponding diazonium salt and a coupler, respectively.
A suitable organic solvent such as N,N-dimethylformamide (
It can be synthesized by reacting with a base in DMF) to cause a coupling reaction.

Specific examples of the trisazo compound of the general formula (1) thus obtained are as follows.

Compound NαI Nα2 IJa6 1J+17 Company 8 Compound No. 9 Demon 10 The photoreceptor of the present invention contains a trisazo compound represented by the general formula (1) in the photosensitive layer. How to apply these trisazo compounds According to Fig. 1, Fig. 2
or as shown in FIG.

1 to 3 are conceptual cross-sectional views of different embodiments of the photoreceptor of the present invention, l is a conductive substrate, 20, 21.2
2 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.

In FIG. 1, a trisazo compound, which is a charge generator 'R3, and a charge transporting substance 5 are placed on a conductive substrate L using a resin binder (
A photosensitive layer 20 (Tachibana 11ii, which is usually referred to as a single-layer type photoreceptor) is provided, which is dispersed in a binder).

FIG. 2 shows a photosensitive layer 21 ( The structure is usually referred to as a laminated photoreceptor). A photoreceptor having this configuration is normally used in a negative charging system.

FIG. 3 shows a layer structure opposite to that in FIG. 2, and is normally used in a positive charging system. In this case, it is common to further provide a coating layer 7 to protect the charge generation layer 4.

The reason why the laminated photoreceptor has two types of layer configurations is that even if we try to use a photoreceptor with the layer configuration shown in Figure 2 with positive charging, no charge-transporting material compatible with this has yet been found. This is because they are not. At present, when applying a positive charging method to a laminated type photoreceptor, it is necessary to use a photoreceptor having the layer structure shown in FIG.

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 transporting substance and a resin binder and drying it, and then dispersing particles of a charge generating substance thereon in a solvent or a resin binder. The dispersion is applied and dried, and then a coating layer 7 is formed.
It can be manufactured by forming.

The conductive substrate l 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 (materials such as aluminum, stainless steel, nickel, etc.) It may also be made of metal, glass, resin, etc., 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 a trisazo compound represented by the general formula N) 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 transporting substance can also be added thereto. As a resin binder, polycarbonate, polyester, polyamide, polyurethane9
Epoxy, silicone resin, polymers and copolymers of methacrylic acid esters, 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 a resin binder, polycarbonate 1 polyester, polyamide, polyurethane, epoxy, silicone resin.

Polymers, copolymers, etc. of methacrylic acid esters can be used.

The coating layer 7 has the function of receiving and retaining charges of corona discharge in a dark place, and has the ability to transmit light to which the charge generation layer is sensitive, and transmits light to the charge generation layer upon exposure. 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, and Si
It is also possible to use a mixture of inorganic materials such as n, and materials that reduce electrical resistance such as metals and metal oxides.The coating material is not limited to organic insulating film-forming materials. (It is also possible to form inorganic materials such as 5i02, metals, metal oxides, etc. by methods such as vapor deposition and sputtering.As mentioned above, the coating material should be as transparent as possible in the wavelength region where the light absorption of the charge generating substance is maximum. It is desirable that

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 Trisazo compound 50fi1 represented by the compound fi1
1 part of polyester resin (Vylon; manufactured by Toyobo) 100
11 parts of hydrogen and 1-phenyl-3-(p-diethylaminostyryl)-5-, (baradiethylaminophenyl)-2
- A coating solution was prepared by kneading 100 parts by weight of pyrazoline (ASPP) and a tetrahydrofuran (THF) solvent in a mixer for 3 hours, and a wire was coated on an aluminum-deposited polyester film (person 1-PET), which was a conductive substrate. A photosensitive layer was formed by coating using a bar method so that the film thickness after drying was 15 μm, and a photosensitive member having the structure shown in FIG. 1 was prepared.

Example 2 First, a solution of 100 parts by weight of p-diethylaminobenzaldehyde-diphenylhydrazone (ABPH) dissolved in 700 parts by weight of tetrahydrofuran (THF) and 100 parts by weight of polycarbonate resin (Panlite L-1250) were mixed with THF and dichloromethane. vs l mixed solvent 70
A coating solution prepared by mixing 0 parts by weight of the solution was applied onto an aluminum-deposited polyester film substrate by a wire bar method to form a charge transport layer so that the film thickness after drying was 15 μm.

The compound Pk is placed on the charge transport layer thus obtained.
50 parts by weight of a trisazo compound represented by Ll, 50 parts by weight of a polyester resin (trade name: Vylon 200, manufactured by Toyobo), 50 parts by weight of PMMA and a THF solvent were kneaded in a mixer for 3 hours to prepare a coating solution, and then a coating solution was prepared using a wire bar method. A charge generation layer was formed so that the film thickness after drying was 0.5 μm, and a photoreceptor corresponding to the structure shown in FIG. 3 was produced. However, a coating layer not directly related to the present invention was not provided.

Example 3 A charge transport layer was formed in the same manner as in Example 2, except that the charge transport material in Example 2 was changed from ABPH to α-phenyl-4''-N,N-dimethylaminostilbene, which is a styryl compound. Then, a charge generation layer was further formed to produce a photoreceptor.

Example 4 A charge transport layer was formed in the same manner as in Example 2, except that the charge transport material in Example 2 was changed from ABPH to tri(p-tolyl)amine, which is a triphenylamine compound. A layer was formed to produce a photoreceptor.

Example 5 The charge transport substance in Example 2 was changed from ABPH to 2,5-bis(p-diethylaminephenyl)-1,3,4-oxadiazole, which is an oxadiazole compound, and the rest was the same as in Example 2. A charge transport layer was formed in the same manner as in 2, and a charge generation layer was further 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 V (volts) of the photoreceptor is +6. Ok
This is the initial surface potential when corona discharge of V is performed for 10 seconds to positively charge the surface of the photoreceptor, and then the surface potential is V when held in the dark for 2 seconds with corona discharge stopped.
Measure d (volts), and then irradiate the surface of the photoreceptor with white light with an illuminance of 2 lux to find the time (seconds) it takes for V to be halved, and calculate the half-attenuation exposure amount E1/2 (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, the photoreceptors of Examples 1, 2, and 3°4.5 had a surface potential v, half-attenuation exposure amount E l/21
Both the residual potential V and the residual potential were good. .

Example 6 A coating solution was prepared by kneading 100 parts by weight of the trisazo compounds represented by the above compounds) & 12 to 10 with 100 parts by weight of a polyester resin (trade name: Vylon 200) and a THF solvent for 3 hours in a mixer. Each charge generation layer was formed by coating the support to a thickness of about 0.5 μm. On top of this, apply approximately 15μ of the ASPP coating solution obtained in the same manner as in Example 2.
A photoreceptor having the structure shown in FIG.

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.

The surface potential V (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 negatively charge the surface of the photoreceptor, and the surface potential Vd is then maintained in the dark for 2 seconds with corona discharge stopped.
(volts), and then the illuminance 2 on the photoreceptor surface.
Find the time (seconds) it takes for V- to be halved after irradiating the lux white light and calculate the half-attenuation exposure amount E 1/2 (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 2, the trisazo compound Nci
The photoconductor using 2 to 1 JqlO also had good half-attenuation exposure 11E1yx and residual potential vr.

〔Effect of the invention〕

According to the present invention, since the trisazo compound represented by the general formula (1) is used as a charge generating substance on a conductive substrate, the photoreceptor is highly sensitive even when charged positively and negatively and has 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 drawings]

1.2 and 31! FIG. 1 is a conceptual cross-sectional view showing different embodiments of the photoreceptor of the present invention. 1 Conductive substrate, 311! charge-generating substance, 4 charge-generating layer, 5 charge-transporting substance, 6 charge-transporting layer, 7 coating layer,
20.21.22 Photosensitive layer.

Claims (1)

[Scope of Claims] 1) An electrophotographic photoreceptor comprising a photosensitive layer containing at least one trisazo compound containing a terthiophene structure represented by the following general formula (I). ▲There are mathematical formulas, chemical formulas, tables, etc.▼………………(I) (In formula (I), R_1, R_2, R_3, R_4, R
_5, R_6 and R_7 are each hydrogen atom, halogen atom, hydroxy group, alkyl group, alkoxy group, allyl group, aldehyde group, 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 a cyano group, and Ar represents a substituted or unsubstituted aromatic ring or aromatic heterocyclic group. )