JPS63296055A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To enhance sensitivity in both positive and negative chargings, and repetition characteristics of a photosensitive body by incorporating one of trisazo compounds each having sexithiophene structures represented by a specified formula in a photosensitive layer. CONSTITUTION:The electrophotographic sensitive body is obtained by forming on a conductive substrate 1 the photosensitive layer 20 containing an electric charge transfer material 5 and as a charge generating material 3 at least one of the trisazo compounds each having sexithiophene structures represented by formula I in which each of R1-R13 is H, halogen atom., hydroxy, alkyl, alkoxy, allyl, aldehyde, acyl, carboxy, ester, carbamoyl, amino, alkylamino, arylamino, aryl, aralkyl, nitro, or cyano group, and Ar is an optionally substituted aromatic hydrocarbon or aromatic heterocyclic ring.

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 (I) is incorporated into a photosensitive layer formed on a conductive substrate. Contains compounds.

The present invention relates to an electrophotographic photoreceptor characterized by:

[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-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 surface charge in the dark, the function of receiving light and generating charge, and the function of receiving light and transporting charge, all of which can be achieved in one layer. A so-called single-layer photoreceptor with the following functions is laminated with functionally separated layers: a layer that mainly contributes to charge generation, and a layer that contributes to surface charge retention in the dark and charge transport during light reception. There is a so-called laminated 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 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 the latent image with toner, transferring the developed toner image to a support such as paper, and fixing it. After the toner image is transferred, the photoreceptor is charged, the 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 film-forming properties. For example, poly-N-vinylcarbazole and 2.
4.7-) Photoreceptor consisting of lystrofluoren-9-one (described in US Pat. No. 3,484,237), photoreceptor containing organic pigment as a main component JP-A-47-37543
(described in Japanese Unexamined Patent Publication No. 10735/1983), 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]

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 kind of trisazo compounds containing a sexithiophene structure represented by the following general formula (1). .

(In formula (1), R1+ Ran R1+ R4
1Ran R11+R1', Re, Rs, R+.

+ R111RI2 right and R13 are each a 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.

7 arylamide groups, aryl group, aralkyl group.

It represents a nitro group or a cyano group, and ^r represents a substituted or unsubstituted aromatic ring or aromatic heterocyclic group. ) [Function] There is no known example in which the trisazo compound represented by the general formula (1) is used in a photosensitive layer. In order to achieve the above objective, the present inventors conducted numerous experiments on these trisazo compounds while conducting intensive studies on various organic materials. We have 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 we have developed a photoreceptor with high sensitivity and excellent repeatability. I ended up getting it.

〔Example〕

The trisazo compound of the general formula (I) 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.

To the tris-ar of the general formula (1) thus obtained,
('l') Dimension i
d d d2
Sound
≧7■ B The photoreceptor of the present invention contains a trisazo compound represented by the general formula (I) in the photosensitive layer.
or as shown in FIG.

1 to 3 are conceptual cross-sectional views of different embodiments of the photoreceptor of the present invention, in which 1 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 a photosensitive layer 20 (usually called a single-layer photoreceptor) in which a trisazo compound as 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 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 of 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 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 then applying a charge-transporting substance and a resin binder thereon. It can be produced by applying a dissolved 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 1 serves as an electrode for the photoreceptor and at the same time serves as a support for other layers, and may be cylindrical, plate-shaped, or film-shaped, and may be made of metal such as aluminum, stainless steel, or nickel metal. Alternatively, it may be made of glass, resin, or the like and subjected to conductive treatment.

The charge generation layer 4 is formed by applying a material in which particles of the charge generation substance 3 made of a trisazo compound represented by the general formula (I) are dispersed in a resin binder, and generates charges by receiving light. do. In addition, the charge transport layer 6 and the coating layer 7 for the generated charges at the same time have a high charge generation efficiency.
It is important to have good injection properties even in low electric fields with little dependence on electric fields. 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. Resin binders include polycarbonate, polyester, polyamide, polyurethane, epoxy, and silicone resin.

Polymers and copolymers 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 and glass resin, 5i
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 (inorganic materials such as Si02, metals, metal oxides, etc. can also be formed by methods such as vapor deposition and sputtering.The coating material is As described above, it is desirable that the charge generating material be as transparent as possible in the wavelength region where the light absorption is maximum.

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 50 represented by the above compound Nc1.1
Polyester resin (Vylon: manufactured by Toyobo) 10 parts by weight
0 parts by weight and 1-phenyl-3-(p-diethylaminostyryl)-5-(vala-diethylaminophenyl)-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 then coated on an aluminum-deposited polyester film (AJ-PET), which is a conductive substrate, using a wire bar method. A photosensitive layer was formed 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. 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 by a wire bar method to form a charge transport layer so that the film thickness after drying was 15 μm.

The compound Mi is placed on the charge transport layer thus obtained.
3 with 50 parts by weight of the trisazo compound represented by ll, 50 parts by weight of polyester resin (trade name Byron 200: manufactured by Toyobo), 50 parts by weight of PMM A and THF solvent.
The coating solution was prepared by kneading with a time mixer, and applied using a wire bar method to form a charge generation layer so that the film thickness after drying was 0.5 μm, corresponding to the configuration shown in Figure 3. A photoreceptor 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-diethylaminophenyl)-1,3,4-oxadiazole, which is an oxadiazole compound, and the other conditions were as in Example 2. A charge transport layer was formed in the same manner as above, 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 V3 (volts) 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 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 find the half-attenuation exposure amount E+, □ (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 V (volt).

As shown in Table 1, the photoreceptor of Example 1, 2.3° and 4.5 has a surface potential V, and a half-attenuation exposure amount E I / 2
+Residual potential Vr were both good.

Example 6 A coating solution was prepared by kneading 100 parts by weight of each of the trisazo compounds represented by compounds 2 to klo 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 applying the mixture onto the body to a thickness of about 0.5 μm. 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, thereby producing a photoreceptor having the structure shown in FIG. 2.

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.
Calculate the time (seconds) it takes for V to be halved after irradiating the lux white light, and calculate the half-attenuation exposure amount E + zt (lux seconds)
And so. In addition, as shown in Table 2 when white light with an illumination intensity of 2 lux was irradiated for 10 seconds, the trisazo compound seeds 2 to 2
Also for the photoreceptor using Na 10, the half-attenuation exposure amount E
Both l/l and residual potential vr were good.

〔Effect of the invention〕

According to the present invention, since the trisazo compound represented by the general formula (I) is used as a charge-generating substance on a conductive substrate, the photoreceptor is highly sensitive even when positively charged and negatively charged, 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 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 material, 6. Charge transporting layer, 7. Covering layer, 20.21.22 Photosensitive layer. Figure 1 Figure 2 Figure 3

Claims (1)

[Scope of Claims] 1) An electrophotographic photoreceptor comprising a photosensitive layer containing at least one trisazo compound containing a sexithiophene 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, R_7, R_8, R_9, R_1_0,
R_1_1, R_1_2 and R_1_3 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, a carboxyl group, an ester group, a carbamoyl group, an amino group,
It represents an alkylamino group, an arylamino group, 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. )