JPS63163369A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To enhance sensitivity and characteristics against repeated uses by using a specified azo compound as the electric charge generating material of a photosensitive layer to be formed on a conductive substrate. CONSTITUTION:The photosensitive layer contains at least one of the azo compounds having diphenylthiophene structure represented by formula I and II in which each of R1-R22 is H, halogen atom, OH, alkyl, alkoxy, allyl, aldehyde, acyl, carbonyl, ester, carbamoyl, amino, alkylamino, arylamino, aryl, aralkyl, nitro, or cyano group; 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 and superior in characteristics against repeated uses.

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, in a photosensitive layer formed on an electrically conductive substrate, compounds of the general formulas (I) and (I[ ) 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) have been made using 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 a conductive material containing these in a resin binder. Dispersed materials 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 layer with functionally separated layers: 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. There is a laminated type 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 of text, pictures, etc. on the document by exposing the surface of the charged photoconductor to light, and This is done by developing an electrostatic latent image with toner and fixing the developed toner image onto a support such as paper. , subject to reuse.

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, PoIJ-N~vinyl carbasol and 2
．． 4.7-t! J nitrofluoren-9-one (described in U.S. Pat. No. 3,484,237)
, Photoreceptor containing organic pigment as main component JP-A-47-375
43 (described in Japanese Patent Application Laid-Open No. 47-10735), 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 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 fully satisfies all the characteristics required of an electrophotographic photoreceptor, especially in terms of photosensitivity and repeatability. There were problems with the characteristics during 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.

[Failure to solve the problem]

In order to achieve the above object, the present invention provides an electrophotographic material having a photosensitive layer containing at least one kind of azo compounds containing a diphenylthiophene structure represented by the following general formula (1) or (It). Use as a photoreceptor.

(In formulas (1) and (II), R and Raa are each a hydrogen atom, a halogen atom, a hydroxy group, an alkyl group, an alkoxy group, an allyl group, and an aldehyde group.

Represents an acyl group, carbonyl group, ester group, carbamoyl group, amine group, alkylamino group, arylamino group, aryl group, aralkyl group, nitro group or cyano group, N=NA represents an azo residue, N=NA, -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 (n) 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 materials. Such general formula (1) or (II)
It was discovered that the use of a specific azo compound represented by the following 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 (n) 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 (1) and (I[) thus obtained are as follows.

Compound Nαl No, 2 No, 3, Nα4 No, 6 No, 7 Compound Nα8 No, 9 No, 1 O CLII Nα12 No, 13 No, 14 Compound No, l 5 No, l 6 No, 17 t1α18 No, 19 No , 2 O No, 21 Compound No, 22 Nα23 No, 24 N(L26 No, 27 No, 28 Compound Nα29 Nα31 No, 32 No, 33 No, 35 The photoreceptor of the present invention has the general formula (I) and (n ) contains an azo compound shown in the photosensitive layer,
Depending on how these azo compounds are applied,
or as shown in FIG.

1 to 3 are conceptual cross-sectional views of different embodiments of the photoreceptor of the present invention, where ■ 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.

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 (a photosensitive layer 21 (
The structure is usually referred to as a laminated photoreceptor).

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

In this case, a coating layer 7 is generally provided to protect the charge generation layer 4, and the photosensitive layer 22 is a charge transport layer 6.
．． Charge generation layer 4. It is composed of a covering layer 7.

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 given.

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 coating this dispersion on 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. It can be produced by applying a dispersion, drying it, and further forming a coating layer thereon.

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 formulas (1) and (I[) 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 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 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 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. In addition, these organic materials and glass resin, 81
It is also possible to use a mixture of inorganic materials such as 02 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 using inorganic materials such as 810□, 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 of the azo compound represented by the compound Nα1 was mixed with 100 parts of polyester resin (Pylon: manufactured by Toyobo) and 1-phenyl-5-(P-diethylaminostyryl)-
100 parts by weight of 5-(paradiethylaminophenyl)-2-pyrazoline (ASPP) and tetrahydrofuran (T
HF') solvent for 3 hours using a layer mixer to prepare a coating solution, and coated onto an aluminum-deposited polyester film (Al-PET), which is a conductive substrate, using a wire bar method. After drying, the coating solution was prepared. A photosensitive layer was formed to have a thickness of 15 μm to produce a photoreceptor.

Example 2 First, a solution of 100 parts by weight of P-diethylaminobenzaldehyde-diphenylhydrazone (ABPH) dissolved in tetrahydrofuran (THF>700 parts by weight) and 100 parts by weight of polycarbonate resin (Panlite L-1250) were mixed with THF and dichloromethane. 1:1 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 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 Vylon 200: manufactured by Toyobo Co., Ltd.), P
A coating solution was prepared by kneading 50 parts by weight of M M A and a THF solvent in a layer mixer for 3 hours, and coating with a wire bar to form a charge generation layer so that the film thickness after drying was 0.5 μm, and then photosensitive. The body was created.

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

Example 5 In Example 2, the charge transport substance was changed to ABPH, and 2゜5-bis(, which is an oxadiazole compound) was used instead of ABPH.
Using p-diethylaminophenyl)-1°3,4-oxadiazole, a charge transport layer was formed in the same manner as in Example 2, and a charge generation layer was further formed to prepare 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 (voltage) of the photoreceptor is +6.
This is the initial surface potential when corona discharge of OkV is performed for 10 seconds to positively charge the surface of the photoreceptor, and then the surface potential Vd (volts) is when the corona discharge is stopped and the surface is held in the dark for 2 seconds. Then, the surface of the photoreceptor was irradiated with white light with an illuminance of 2 lux, and the time (seconds) until Vd was halved was determined to be the half-attenuation exposure amount El/2 (lux seconds). White light with an illuminance of 2 lux and 10
The surface potential when irradiated for seconds is the residual potential V, (volt)
And so.

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 Nα35
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. A coating solution of ΔSPP obtained in the same manner as in Example 2 was applied onto this 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 -6.0 kV 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 then the surface potential v is when the corona discharge is stopped and the surface is held in the dark for 2 seconds.
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) until yd is halved, and calculate the half-attenuation exposure amount El/2 (lux seconds). And so. Further, the surface potential when white light with an illuminance of 2 lux was irradiated for 10 seconds was defined as the residual potential Vr (volt).

As seen in Table 2, compounds No. 2-Nα35
Even in the photoconductor using the above method, both the half-attenuation exposure amount and the residual potential were good.

Table 2 (Part 1) Table 2 (Part 2) Table 2 (Part 3) [Effects of the Invention] According to the present invention, as the charge generating substance of the photosensitive layer provided on the conductive substrate, the general formula (1) Since the azo compounds represented by ) and (II) are used, it is possible to obtain a photoreceptor with high sensitivity and excellent repeatability even in positive and negative charging.

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

[Brief explanation of the drawing]

Figures 1, 't, 2 and 13 are conceptual sectional views showing different embodiments of the photoreceptor of the present invention.

Claims (1)

[Scope of Claims] 1) A photosensitive material for electrophotography, characterized by having a photosensitive layer containing at least one type of azo compound containing a diphenylthiophene structure represented by the following general formula (I) or (II). body. ▲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 to R_2_2 are each a hydrogen atom , halogen atom, hydroxy group, alkyl group, alkoxy group, allyl group, aldehyde group, acyl group, carbonyl group, ester group, carbamoyl group, amino group, alkylamino group, arylamino group, aryl group, aralkyl group, nitro group or represents a cyano group,
N=N-A_1 represents an azo residue, N=N-A_2-N
=N represents a disazo residue. )