JPH01183664A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To improve the sensitivity and repetitive characteristic of a photosensitive body by providing a photosensitive layer contg. specific disazo compds. CONSTITUTION:One on more than one kinds of the compds. expressed by formula I are incorporated as a charge generating material into the photosensitive layer. In formula I, -D- denotes any group among formulas II-IV; Cp denotes a residual coupler group (e.g.: the group expressed by formula V, Y1-Y18 in formulas II-IV denote H, cyano, carbamoyl, etc.; A1, A2 denote H, cyano, aralkyl, etc.; Z in formula V denotes a residual group forming a polycyclic arom. ring or heterocycle; X1 denotes OR1, NR2R3 (R1-R3 denote H, alkyl, etc.). The formation of the photosensitive layer into the constitution laminated with the charge generating layer and charge transfer layer is also possible and the constitution thereof in a single layer is possible as well.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to an electrophotographic photoreceptor, and more specifically, a disazo compound represented by the formula (IJ) is incorporated into a photosensitive layer formed on a conductive substrate. The present invention relates to an electrophotographic photoreceptor characterized by containing the following.

[Prior Art] Conventionally, photosensitive materials for electrophotographic photoreceptors (hereinafter also referred to as photoreceptors) have been made of inorganic photoconductive substances such as selenium or selenium alloys, or resins containing inorganic photoconductive substances such as zinc oxide or cadmium sulfide. Dispersed in binder, BoI
Organic photoconductive substances such as J-N-vinylcarbazole or polyvinylanthracene, organic photoconductive substances such as phthalocyanine compounds or disazo compounds, or these organic photoconductive substances dispersed in a resin binder, etc. It's being used.

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 a charge, as well as the function of receiving light and transporting a charge. There is a so-called laminated photoreceptor in which functionally separated layers are laminated, including a layer that 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, transferring the developed toner image to a support such as paper, and fixing it. After the toner image has been transferred, the photoreceptor is subjected to static neutralization, removal of residual toner, photostatic static elimination, etc. , subject to reuse.

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, po'J-N-vinylcarbazole and 2
．． 4.7-) dinitrofluoren-9-one (described in U.S. Pat. No. 3,484,237),
Photoreceptor containing organic pigment as main component (Japanese Patent Application Laid-Open No. 47-3754
(described in Japanese Patent Application Laid-Open No. 10735/1983), and photoreceptors whose main component is a eutectic complex consisting of a dye and a resin). Furthermore, there are many new azo compounds and perylene compounds.As mentioned above, organic materials have many advantages that inorganic materials do not have. At present, it has not yet been obtained, and there have been problems in particular with respect to 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. In order to achieve the above purpose,
According to the invention.

A photoreceptor for electrophotography is provided with a photosensitive layer containing at least one type of disazo compound represented by the following formula (I).

Cp-N=N-D-N=N-Cp -(I) [In formula (I), -D- represents one of the following formulas (II) to (IV), and Cp is a coupler residue. Indicates the group.

1A2 AI Al A, A2 (Formula (II) to (rV)) In which, Y1 to Y18 are a hydrogen atom, a cyano group, a carbamoyl group, a carboxyl group, an ester group, an acyl group, a halogen atom, and a sulfonic acid group.

an optionally substituted alkyl group, a cycloalkyl group,
It represents an alkenyl group, an aryl group, or an aromatic heterocyclic group, and AI and A2 are hydrogen atoms and cyan groups.

Indicates an optionally substituted aralkyl group, an optionally substituted aromatic hydrocarbon group, or an aromatic heterocyclic group. )] Furthermore, it is preferable that the coupler residue Cp in formula (I) has a structure of any one of the following formulas (V) to (■).

[In formulas (V) to (■), Z is a residue that is fused with a benzene ring to form a polycyclic aromatic ring or a heterocycle, and Xl is O
R+ or N R2R3 (R1, R2 and R5 represent a hydrogen atom, an alkyl group, an optionally substituted aryl group or an aromatic heterocyclic group), x2 and X5 are an optionally substituted alkyl group, aryl group or aromatic heterocyclic group, X3 and x6 are hydrogen atoms,
It represents a cyano group, a carbamoyl group, a carboxyl group, an ester group, or an acyl group, and X4 is a hydrogen atom, an optionally substituted alkyl group, a cycloalkyl group, or an alkenyl group.

It represents an aryl group or an aromatic heterocyclic group, and Xl and X are a hydrogen atom and a halogen atom, respectively.

Represents a nitro group, or an optionally substituted alkyl group or alkoxy group, and X is an alkyl group.

It represents an aryl group or a carboxyl group, and X+o represents an optionally substituted aryl group or an aromatic heterocyclic group.

] [Function] There is no known example in which the disazo compound represented by formula (I) above is used in a photosensitive layer. In order to achieve the above object, the present inventors conducted a number of experiments on these disazo compounds while conducting intensive studies on various organic materials. It has been found that the use of a specific disazo compound represented by formula (I) as a charge generating substance is extremely effective in improving electrophotographic properties, and a photoreceptor with high sensitivity and excellent repeatability is obtained. It has come to this.

〔Example〕

The disazo compound of 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.

Specific examples of the disazo compound of formula (I) thus obtained are as follows.

I+I uCH3CHI N937 N941 N953 compound tooth 55 56 ce ce CH3CH.

CH3CH3N! ? 64 CH3LH3 The photoreceptor of the present invention contains a disazo compound represented by the above formula (I) in the photosensitive layer.
Alternatively, it can be used 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, 2a, 2b,
2c is a photosensitive layer, 3 is a charge generating substance, 4 is a charge generating layer,
5 is a charge transport material, 6 is a charge transport layer, and 7 is a coating layer.

Figure 1 shows a photosensitive layer 2a (usually called a single-layer photoreceptor) in which a disazo compound as a charge generating substance 3 and a charge transporting substance 5 are dispersed in a resin binder on a conductive substrate l. configuration) is provided.

FIG. 2 shows a photosensitive layer 2 consisting of a conductive substrate 1 and a charge generating layer 4 containing a disazo compound as a charge generating substance 3, and a charge transporting layer 6 mainly composed of a charge transporting substance 5.
b (a configuration commonly 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 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 particles of the charge generation substance 3 made of a disazo compound represented by formula (I) are dispersed in a resin binder, and generates charges by receiving light. do. 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. Resin binders include polycarbonate, polyester, and polyamide.

Polyurethane, 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. 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 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, S
It is also possible to use a mixture of inorganic materials such as iO□ 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 inorganic materials such as Sin, metals, metal oxides, etc. can also be formed 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 disazo compound represented by the compound Nα1 was mixed with 100 parts by weight of a polyester resin (Vylon manufactured by Toyobo) and 1-phenyl-3-(p-diethylaminostyryl)-5-(p-diethylaminophenyl)- A coating solution was prepared by kneading 100 parts by weight of 2-pyrazoline (ASPP) and a tetrahydrofuran (THF) solvent in a mixer for 3 hours, and then coated with a wire bar on an aluminum-deposited polyester film (^β-PET), which is a conductive substrate. A photoreceptor having the structure shown in FIG. 1 was prepared by applying the photoreceptor using a method such that the photoreceptor layer had a thickness of 15 μm after drying.

Example 2 tf, p-diethylaminobenzaldehyde-diphenylhydrazone (ABPF (>100 weight 1ifl'lS) dissolved in 700 parts by weight of tetrahydrofuran (THF) and polycarbonate resin (Panlite L-1250)
A coating solution prepared by mixing 100 parts by weight with 700 parts by weight of a 1:1 mixed solvent of THF and dichloromethane was applied onto an aluminum vapor-deposited polyester film substrate using a wire bar method, and the film was dried. A charge transport layer was formed to have a thickness of 15 μm. On the thus obtained charge transport layer, 50 parts by weight of a disazo compound represented by the compound Nα1 and a polyester resin (trade name Vylon 20) were added.
0: Made by Toyo*>50 parts by weight, 50 parts by weight of PMMA TH
A coating solution was prepared by kneading with F solvent in a mixer for 3 hours, and the coating solution was applied using a wire bar method, resulting in a film thickness of 0.5 after drying.
A charge generation layer was formed to have a thickness of .mu.m, and a photoreceptor having the structure shown in FIG. 3 was manufactured. 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 an oxadiazole compound) 2) 5-bis(p-diethylaminophenyl)-1,3,4-oxadiazole, and the rest was carried out A charge transport layer was formed in the same manner as in Example 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, (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 vd.
(volts), and then the illuminance 2 on the photoreceptor surface.
Calculate the time (seconds) it takes for VD to be halved after irradiating the white light of Lux.Half-attenuation exposure amount E172 (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 seen in Table 1, the photoreceptors of Examples 1.2, 3 and 4.5 had a surface potential Vs and a half-attenuation exposure E+/21.
Both residual potential Vr were good.

Example 6 100 parts by weight of the disazo compounds represented by the compounds Nα2 to Nα75 were mixed together with 100 parts by weight of a polyester resin (trade name Vylon 20 [1) and a THF solvent for 3 hours using a mixer to prepare a coating solution, Each charge generation layer was formed by coating the aluminum support with a thickness of about 0.5 μm. On top of this, a coating solution for a charge transport layer obtained in the same manner as in Example 2 except that the charge transport substance in Example 2 was changed from ABPH to ASPP was applied to a thickness of about 15 μm to form a charge transport layer. A photoreceptor was fabricated.

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 surface potential Vt (volts) was measured when the photoreceptor surface was negatively charged for 2 seconds, then kept in the dark for 2 seconds with corona discharge stopped, and then white light with an illuminance of 2 lux was irradiated onto the photoreceptor surface. time until Vd becomes half (seconds)
was determined and set as the half-attenuation exposure amount E172 (lux/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).

Table 2 (Part 2) Table 2 (Part 3) Table 2 (Part 4) Table 2 (Part 5) As seen in Table 2, the disazo compounds Nα2~
Even in the photoreceptor using Nα75, the half-attenuation exposure amount E
Both l/2 + and residual potential V are good.

〔Effect of the invention〕

According to the present invention, since the disazo compound represented by formula (I) is used as a charge generating substance on a conductive substrate, a photoreceptor with high sensitivity and excellent repeatability even in positive and negative charging can be obtained. can be obtained.

Furthermore, it is possible to improve durability by providing a coating layer on the surface as necessary.

BRIEF DESCRIPTION OF THE DRAWINGS FIGS. 1, 2, and 3 are conceptual sectional views showing different embodiments of the photoreceptor of the present invention. 1 Conductive substrate, 2a, 2b, 2cm photosensitive layer, 3
Charge generating material, 4 Charge generating layer, 5 Charge generating material 3 Charge generating material No. 1 Figure 2 Figure 3

Claims (1)

[Scope of Claims] 1) An electrophotographic photoreceptor comprising a photosensitive layer containing at least one disazo compound represented by the following general formula (I). Cp-N=N-D-N=N-Cp...(I) [Formula (
In I), -D- represents a structure of any of the following general formulas (II) to (IV), and Cp represents a coupler residue. ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (II) ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (III) ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (IV) (In formulas (II) to (IV), Y_1 to Y_1_8 are hydrogen atoms, cyano groups, carbamoyl groups, carboxyl groups, ester groups, acyl groups, halogen atoms, sulfonic acid groups, optionally substituted alkyl groups, cycloalkyl groups, alkenyl groups, aryl groups, or aromatic groups Indicates a heterocyclic group, A_
1, A_2 represents a hydrogen atom, a cyano group, an optionally substituted aralkyl group, an optionally substituted aromatic hydrocarbon group, or an aromatic heterocyclic group. )] 2) In the photoreceptor according to claim 1, Cp in the general formula (I) is represented by the following general formulas (V) to (VIII).
An electrophotographic photoreceptor characterized by being a disazo compound having one of the following structures. ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (V), ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (VI) ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (VII), ▲ Mathematical formulas,
Chemical formulas, tables, etc. are available▼(VIII) [In formulas (V) to (VIII), Z is a residue that is fused with a benzene ring to form a polycyclic aromatic ring or a heterocycle, X_1
is OR_1 or NR_2R_3 (R_1, R_2 and R_3 represent a hydrogen atom, an alkyl group, an optionally substituted aryl group or an aromatic heterocyclic group), X_2
and X_5 each represent an optionally substituted alkyl group, aryl group, or aromatic heterocyclic group; X_3 and X_6 represent a hydrogen atom, a cyano group, a carbamoyl group, a carboxyl group, an ester group, or an acyl group;
4 represents a hydrogen atom, an optionally substituted alkyl group, a cycloalkyl group, an alkenyl group, an aryl group, or an aromatic heterocyclic group, and X_7 and X_8 are each a hydrogen atom, a halogen atom, a nitro group, or a substituted X_9 represents an alkyl group, an aryl group, or a carboxyl group;
1_0 represents an optionally substituted aryl group or aromatic heterocyclic group. ]