JPH02247657A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To enhance sensitivity and repetition characteristics of a photosensitive body by incorporating a specified bisazo compound in a photosensitive layer. CONSTITUTION:The photosensitive layer of this photosensitive body contains as an electric charge generating material at least one of the bisazo compounds represented by formula I or II in which Yi is H, halogen, or the like; A is a group of formula III, IV, or the like; Z is a polycyclic aromatic group or a heterocyclic group; X1 is OR1 or NR2R3; each of R1, R2, and R3 is alkyl, or the like; X2 is alkyl, aryl, or the like; X3 is H, cyano, or the like; and X4 is H, alkyl, or the like. The photosensitive layer may be of a single layer structure or laminated layer structure, and hydrazone compounds and the like can be used for a charge transfer material.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an electrophotographic photoreceptor, and more particularly to an electrophotographic photoreceptor that utilizes a novel charge-generating substance.

[Conventional technology]

Conventionally, photosensitive materials for electrophotographic photoreceptors (hereinafter also referred to as photoreceptors) include inorganic photoconductive substances such as selenium or selenium alloys, and inorganic photoconductive substances such as zinc oxide or cadmium sulfide in resin binders. organic photoconductive substances such as poly-N-vinylcarbazole or polyvinylanthracene, organic photoconductive substances such as phthalocyanine compounds or bisazo compounds dispersed in a resin binder or vacuum-deposited. and other items are being used.

The photoreceptor also needs to 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 three layers. The so-called single-layer type photoreceptor has both a so-called single-layer type photoreceptor, and the so-called laminated type photoreceptor that has two functionally separated layers: a layer that mainly contributes to charge generation, a layer that contributes to surface charge in the dark, and a layer that contributes to charge transport during light reception. I have a body. 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 such as text or pictures on the original on the surface of the charged photoconductor, and forming an electrostatic latent image on the surface of the charged photoconductor. After the toner image has been transferred, the photoreceptor is subjected to static electricity removal, removal of residual toner, photostatic static removal, etc. before being reused. be done.

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-dolinitrofluorene-9-one (described in U.S. Pat. No. 3,484,237), a photoreceptor containing organic i1 material as a main component (JP-A-47-3754)
3), and a photoreceptor whose main component is a eutectic complex consisting of a dye and a resin (described in JP-A-47-10785). Furthermore, many new azo compounds and perylene compounds have been put into practical use.

[Problem to be solved by the invention]

However, although organic materials have many advantages that inorganic materials do not have, the current situation is that organic materials that fully satisfy all the characteristics required of electrophotographic photoreceptors have not been obtained.

The present invention has been made in view of the above-mentioned points, and its object is to provide an electrophotographic photoreceptor having high sensitivity and excellent repeatability by using a novel charge-generating substance in the photosensitive layer.

[Means to solve the problem]

According to the present invention, the above object is achieved by providing a photosensitive layer 20.21.22 containing at least one type of bisazo compound represented by the general formula (1-a) or (1-b).
a> [2N-a) and (1-b), YN means Y, Y, and Y, each of Y, Yt, and Y is a hydrogen atom, a halogen atom, a cyano group, or an alkyl group. , represents an alkoxy group or an aryl group, and A is the general formula (n)
It is a coupler residue represented by ~(V).

In formulas (1m) to (V), 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 NR, R, (R,, R, and R5 each represent a hydrogen atom, an optionally substituted alkyl group, an aryl group, or an aromatic heterocyclic group), x2 and X,
each represents an optionally substituted alkyl group, aryl group or aromatic heterocyclic group, and x3 and X are a hydrogen atom and a cyano group.

represents a carbamoyl group, carboxyl group, ester group, or acyl group; X represents a hydrogen atom, an optionally N-substituted alkyl group, a cycloalkyl group, an alkenyl group, an aryl group, or an aromatic heterocyclic group; , X, and
each represents a hydrogen atom, a halogen atom, a nitro group, or an optionally substituted alkyl group or alkoxy group, and Xs represents an alkyl group, an aryl group, a carboxyl group,
represents an ester group, and Xlo represents an optionally substituted aryl group or an aromatic heterocyclic group. ] is achieved.

The general formula (J-a) or (1-) used in the present invention
The bisazo compound b) is prepared by adding the corresponding diamine to the bisazo compound using a conventional method. Tetrazotized by 1'flI,
The resulting tetrazonium salt and coupler can be synthesized by reacting with a base (such as acetic acid) in a suitable organic solvent such as N,N-dimethylformamide (DMF) to cause a coupling reaction.

Specific examples of the bisazo compound of the general formula (1-a) or (I-b) that can be obtained in this manner (!1) are as follows.

(Published by I-a) The contents of Y, Y, Y, and the coupler residue Δ are shown in Table 1. Each compound from kl to seed 20 is f6
It may be any of the 111 isomers.

Table 1 (Part 1) (Part 2) Table 1 (Part 1) The structures of the coupler residues (Cp-1 to Cp-20) are shown in Table 2.

(Part 2) The photoreceptor of the present invention has the general formula (1-a) or (I-b)
) is contained in the photosensitive layer, and depending on the application of these bisazo compounds, they can be used as shown in FIG. 1, FIG. 2, or FIG. 3.

1 to 3 are conceptual cross-sectional views of the photoreceptor of the present invention.
20, 21 and 22 are a conductive substrate, 20, 21 and 22 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 20 (commonly referred to as a single-layer photoreceptor) in which a bisazo compound as a charge generating substance 3 and a charge transporting substance 5 are dispersed in a resin binder on a conductive substrate l.
is provided.

FIG. 2 shows a charge generation layer 4 containing a bisazo compound as a charge generation substance 3 and a charge transport substance 5 on a conductive substrate l.
A photosensitive layer 21 consisting of a laminated layer with a charge transport layer 6 mainly composed of
(a configuration commonly referred to as a laminated photoreceptor).

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

The reason for the Jl configuration shown in Figures 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 Figure 2 is made by coating a conductive substrate with a dispersion obtained by dispersing particles of a charge-generating substance in a solvent or a resin binder, drying it, and then dissolving a charge-transporting substance and a resin binder thereon. Apply solution.

It can be produced by drying.

The photoreceptor shown in Figure 3 is made by coating a conductive substrate with a solution containing a charge transport substance and a resin binder.

After drying, a dispersion obtained by dispersing charge-generating substance particles in a solvent or resin binder is applied on top.

It can be produced by drying.

The conductive substrate 1 serves as an electrode for the photoreceptor and at the same time serves as a support for other layers, and has a cylindrical or plate shape.

It may be in the form of a film, and the material may be a metal such as aluminum, stainless steel, or nickel, or a material made of glass, No. 11 resin, etc., which has been subjected to a conductive treatment.

The charge generation layer 4 includes a charge generation substance 3 made of a bisazo compound represented by the general formula (1-a) or (I-b).
It is formed by applying a material in which particles are dispersed in a resin binder, and it receives light and generates an electric charge. In addition to its high charge generation efficiency, the ability to inject the generated charges into the charge transport layer 6 and coating layer 7 is also important, and it is desirable that the charge generation layer has little dependence on electric fields (good injection even in low electric fields is desirable). It is also possible to use a charge-generating substance as the main ingredient, and add a charge-transporting substance to it.As a resin binder, polycarbonate or polyester is used.

polyamide, polyurethane, epoxy, silicone resin,
It is possible to use a suitable combination of polymers, copolymers, etc. of methacrylic acid esters.

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 resin, silicone resin, methacrylic acid ester polymers and copolymers, 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, S
It is also possible to use a mixture of ma materials such as +Oz 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.

[Effect]

There is no known example in which a bisazo compound represented by the general formula (1-a) or (I-b) is used in a photosensitive layer.

In order to achieve the above objective, the present inventors conducted numerous experiments on these bisazo compounds while conducting intensive studies on various organic materials. The above general formula (1
- It has been discovered that the use of a specific bisazo compound represented by (a) or (1-b) as a charge-generating substance is extremely effective in improving electrophotographic properties, and the present invention provides a photoreceptor with high sensitivity and repeatable properties. I was able to obtain this.

〔Example〕

Examples of the present invention will be described below.

Example 1 50 parts by weight of the bisazo compound represented by Compound 1 was added to a polyester resin (trade name: Vylon 200, manufactured by Toyobo Co., Ltd.)
100 parts by weight and 1-phenyl-3-(p-diethylaminostyryl)-5-(p-diethylaminophenyl)-
A coating solution was prepared by kneading 100 parts by weight of 2-pyrazoline (A S P P) and a tetrahydrofuran (THF) solvent in a mixer for 3 hours, and the coating solution was applied onto an aluminum-deposited polyester film (^/-PET), which is a conductive substrate. A photoreceptor was prepared by applying the film using a wire bar method so that the film thickness after drying was 15 μm.

Example 2 First, a solution obtained by dissolving 100 parts by weight of p-diethylaminobenzaldehyde-diphenylhydrazone (8BPH) in 700 parts by weight of tetrahydrofuran (THF) and 100 parts by weight of polycarbonate resin (trade name Panlite-1250, manufactured by Teijin) were mixed. A coating solution prepared by mixing 700 parts by weight of a 1:1 mixed solvent of THF and dichloromethane was applied onto an aluminum-deposited polyester film substrate using a wire bar method, and the film thickness after drying was 15 μm. The charge transport layer was formed so as to have the following properties. On the thus obtained charge transport layer, 50 parts by weight of a bisazo compound represented by the compound Nnl and a polyester resin (trade name: Vylon 200
: Toyobo) 50 parts by weight, PMM 85 parts by weight and T H
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 μm.

Example 3 Similar to Example 2, the charge transport substance was changed to ABPH, and α-phenyl 4'-N, which is a 1) λν compound,
A charge transport layer was formed using 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 changed to ABPH, and a triphenylamine compound, tIJ(p-)
A charge transport layer was formed using IJ 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 replaced with 8BPH and an oxadiazole compound, 2°5-bis(p-
A charge transport layer was formed using (diethylaminophenyl)-1,3°4-oxadiazole 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 3.

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 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.
The time (seconds) required for Vd to be halved after irradiation with lux white light was determined as half-attenuation exposure IIE-y2<lux seconds. 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, (volts).

As seen in Table 3, Example 1. 2. 3゜4,
and 5 is half attenuation exposure 1. Both residual potentials were good.

Example 6 Bisazo compound 1 represented by 20 from the compound seed 2
A coating solution was prepared by kneading 00 parts by weight of each polyester resin (trade name: VYLON 200: TOYOBO'llN0O by weight) and a THF solvent for 3 hours in a mixer, and coated on an aluminum support to a thickness of about 0.5 μm. Then, a charge generation layer was formed.

A coating liquid containing ASPP as a charge transport substance obtained by the same method as in Example 2 was applied onto this to a thickness of about 15 μm 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.

Apply a corona discharge of -6, OkV to the surface of the photoreceptor for 10 minutes in the dark.
The surface potential Vd (volts) was measured when the photoreceptor surface was negatively charged for 2 seconds, then held in the dark for 2 seconds with corona discharge stopped, and then white light with an illumination intensity of 2 lux was irradiated onto the photoreceptor surface. time (seconds) until vd is halved
was determined and set as half-attenuation exposure ff1E17□ (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). The results are shown in Table 4.

Table 4 (Part 1) Table 4 (Part 2) Generation layer, 5 Charge transport material, 6 Covering layer, 20.21.22 Photosensitive layer.

Charge Transport Layer [Effects of the Invention] According to the present invention, since the bisazo compound represented by the general formula (1-a) or (I-b) is used as a charge generating substance on a conductive substrate, positive It is possible to obtain a photoreceptor with high sensitivity and excellent repeatability even when charged and negatively charged. Furthermore, if necessary, a coating layer can be provided on the surface to improve durability.

[Brief explanation of drawings]

FIGS. 1, 2, and 3 are conceptual cross-sectional views showing different embodiments of the photoreceptor of the present invention.

Claims (1)

[Claims] (1) An electrophotographic photoreceptor comprising a photosensitive layer containing at least one bisazo compound represented by the general formula (I-a) or (I-b). ▲There are mathematical formulas, chemical formulas, tables, etc.▼( I -a) ▲There are mathematical formulas, chemical formulas, tables, etc.▼( I -b) [Yi in formulas (I -a) and (I -b) is Y_1, Y
_2 and Y_3, each of Y_1, Y_2, and Y_3 represents a hydrogen atom, a halogen atom, a cyano group, an alkyl group, an alkoxy group, or an aryl group, and A is represented by general formulas (II) to (V). It is 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) ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ ( V) In formulas (II) to (V), Z is a residue that is fused with a benzene ring to form a polycyclic aromatic ring or a heterocycle, and X_1 is O
R_1 or NR_2R_3 (R_1, R_2 and R_3 each represent a hydrogen atom, an optionally substituted alkyl group, an 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,
3 and X_6 represent a hydrogen atom, a cyano group, a carbamoyl group, a carboxyl group, an ester group or an acyl group,
X_4 is a hydrogen atom, an optionally substituted alkyl group,
It represents a cycloalkyl group, an alkenyl group, an aryl group, or an aromatic heterocyclic group, X_7 and X_8 each represent a hydrogen atom, a halogen atom, a nitro group, or an optionally substituted alkyl group or an alkoxy group, and X_9
represents an alkyl group, an aryl group, a carboxyl group, or an ester group, and X_1_0 represents an optionally substituted aryl group or an aromatic heterocyclic group. ]