JPH04128767A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To enhance sensitivity and to improve repetitive characteristics by incorporating at least one kind among specific bisazo compds. as a charge generating material into the photosensitive layer on a conductive base. CONSTITUTION:The bisazo compds. expressed by formula I are incorporated as the charge generating material into the photosensitive layer 20 on the conductive base body 1. In the formula I, A denotes a residual coupler group. The bisazo compds. are easily synthesized by converting an amino compd. to diazo and bringing the diazo into coupling reaction with respectively corresponding couplers in a suitable solvent in the presence of an alkali. The photosensitive layer 20 is formed by dispersing the charge generating material 3 into a soln. dissolved with a charge transfer material 5 and a resin binder and applying this dispersion on the conductive base body 1. The sensitivity is enhanced in this way and the repetitive characteristics are improved.

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 photoreceptor of the general formula <1) or (II) is contained in a photoreceptor layer formed on a conductive substrate. The present invention relates to an electrophotographic photoreceptor containing the bisazo compound shown below.

[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 substances such as poly-N-vinylcarbazole or polyvinylanthracene, organic photoconductive substances such as phthalocyanine compounds or bisazo compounds, and dispersion of these organic photoconductive substances in a resin binder. 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. A so-called single-layer type photoreceptor with a combination of two types of photoreceptors, and a so-called laminated photoreceptor 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 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 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 and fixing the developed toner image to a support such as paper, and removing static electricity from the photoreceptor after the toner image is transferred.

After residual toner is removed and static electricity is removed, it is reused.

In recent years, photoconductive organic dyes with excellent charge generation ability have been developed.

Many photoreceptors using pigments have been proposed, for example, JP-A-47-37543 and JP-A-56-11603.
9, JP-A-57-176055, JP-A-6
Various azo compounds are known from Japanese Patent Publication No. 0-5941, Japanese Patent Publication No. 60-45664, etc.

[Problem to be solved by the invention]

Organic materials have many advantages that inorganic materials do not have, such as flexibility and film-forming properties, but at the same time, there is currently no material that fully satisfies all the characteristics required for electrophotographic photoreceptors. In particular, there are problems with photosensitivity and characteristics during repeated and continuous use.

This invention was made in view of the above points, and
The problem to be solved is to provide an electrophotographic photoreceptor for copying machines that has high sensitivity and excellent repeatability by using a new organic material that has never been used as a charge-generating substance in the photosensitive layer. shall be.

[Means to solve the problem]

In order to solve the above problems, according to the present invention, there is provided an electrophotographic photoreceptor including a photosensitive layer containing at least one type of bisazo compound represented by the following general formula (I) or (U).

(In formula (I) or (II), A represents a coupler residue.) A (coupler residue) in the above general formula (I) or ([[) is represented by the following general formula ([[) or ■ ) is suitable.

×4 In Kari [Formula (III) or ■], Z is a residue that is fused with a benzene ring to form an aromatic polycycle or a heterocycle,
Xll;! OR also L<haNR,, R2 (R, R, and R2 each represent a hydrogen atom, each of the following optionally substituted alkyl groups, aryl groups, and heterocyclic groups), X2 and X represents any of the following optionally substituted alkyl groups, aryl groups, and complex sll groups, Xz and x6 are hydrogen atoms,
Represents any one of a cyano group, a carbamoyl group, a carboxyl group, an ester group, and an acyl group, and X or X1
1 is a hydrogen atom.

The following alkyl groups, cycloalkyl groups, alkenyl groups, and aralkyl groups, each of which may be substituted.

Represents either an aryl group or a complex siI group, x7
and x8 is a hydrogen atom, a halogen atom, a nitro group, and each of the following alkyl groups may be substituted.

represents any of the alkoxy groups, X represents any of the following optionally substituted alkyl groups, aryl groups, carboxyl groups, and ester groups,
+ o represents an optionally substituted aryl group or a heterocyclic group, and Y represents a residue forming a heterocycle. ] The photosensitive layer described above may be a single layer containing a charge generating substance and a charge transporting substance, or a laminated layer comprising a charge generating layer containing a charge generating substance and a charge transporting layer containing a charge transporting substance formed thereon. , a charge transport layer containing a charge transport material and a charge generation layer containing a charge generation material formed thereon.

The compound represented by the general formula (I) or (II) is
An amine compound represented by the following formula (I) or (2) is diazotized by a conventional method, and a corresponding cuff blur is obtained,
It can be easily synthesized by carrying out a coupling reaction in an appropriate solvent (for example, N2N dimethylformamide, dimethylformoquinde, etc.) in the presence of an alkali.

Specific examples of the bisazo compound represented by the general formula (I) thus obtained are as follows.

Further, specific examples of the bisazo compound represented by the general formula (It) are as follows.

[Effect]

There is no known example of using a bisazo compound represented by the general formula (I) or (old) in a photosensitive layer.
While conducting intensive studies on various organic materials to solve the above-mentioned problems, we conducted numerous experiments on these bisazo compounds, and found that although their technical clarification has not yet been fully elucidated, the above-mentioned general formula (I ) or (n)
It was discovered that the use of a specific bisazo 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 photoreceptor of the present invention contains a compound represented by the general formula (I) or (II) in the photosensitive layer as a charge generating substance. The configuration shown in FIG. 2 or 3 can be used.

1 to 3 are conceptual cross-sectional views of the photoreceptor of the present invention, in which 1 is a conductive substrate, 20, 21, and 22 are photosensitive layers, 3 is a charge generation material, 4 is a charge generation layer, and 5 is a charge Transport substance, 6
is a charge transport layer, and 7 is a coating layer.

FIG. 1 shows a compound of general formula (I) or (II) as a charge generating substance 3 and a charge transporting substance 5 on a conductive substrate 1.
The photosensitive layer 20 (
The structure is usually referred to as a single-layer photoreceptor).

FIG. 2 shows a charge generation layer 4 containing a compound of general formula CI) or (II) as a charge generation substance 3 and a charge transport layer 6 mainly composed of a charge transport substance 5 on a conductive substrate 1. A photosensitive layer 21 (commonly referred to as a laminated photoreceptor) consisting of a laminated layer is provided.

In FIG. 3, a photosensitive layer 22 having a layer structure opposite to that in FIG. 2 is provided. In this case, it is common to further provide a coating layer 7 to protect the charge generation layer 4.

The reason for the two types of layer configurations shown in Figures 2 and 3 is that even if the layer configuration shown in Figure 2, which is normally used for a negative charging system, is intended to be used for a positive charging system, there is no compatible charge transport material. This is because the layer structure shown in FIG. 3 is required at the current stage as a positive charging type photoreceptor.

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. 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 liquid, drying it, and further forming a coating layer.

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 in the form of a cylindrical plate or a film, 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 a compound represented by the general formula (I) or formula (I) are dispersed in a resin binder, and receives light to generate charges. Occur. 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 transport substance or the like may be added thereto. Resin binders include polycarbonate, polyester, and polyamide.

Polyurethane, vinyl chloride, Evokin, silicone resin,
Diaryl phthalate resin, butyral resin.

Polymers and copolymers of methacrylic acid esters can be used in appropriate combinations.

The proportion of the compound represented by general formula (I) or (II) is 30% to 95% by weight based on the resin binder, and the dispersion solvent is dichloromethane, dichloroethane,
Examples include ethyl acetate, methyl ethyl ketone, and tetrahydrofuran.

The charge transport layer 6 is formed by applying a material in which a hydrazone compound, a pyrazoline compound, a stilbene compound, a triphenylamine compound, an oxazole compound, an oxadiazole compound, etc. are dissolved and dispersed as an organic charge transport 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, methacrylic acid ester polymers and copolymers, etc. can be used.

The covering layer 7 receives charges of corona discharge in a dark place.

It also has the ability to transmit the light that the charge generation layer is sensitive to, allowing the light to pass through during exposure, reach the charge generation layer, and receive the generated charge and release the surface charge. It is necessary to neutralize and eliminate it.

As the coating material, organic insulating film-forming materials such as polyester and polyamide can be used. Further, these organic materials can be used in combination with inorganic materials such as glass resins and Sin, metal alkoxy compounds having film-forming ability, and materials that reduce electrical resistance such as metals and metal oxides.

The coating material is not limited to organic insulating film forming materials, but may also be formed using inorganic materials such as 5i02, 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.

Examples of the present invention will be described below.

Example 1 50 parts by weight of the compound represented by the compound NαI-1 was added to a polyester resin (trade name: Vylon 200, manufactured by Toyobo) 1
00 parts by weight and 1-phenyl-3-(p-diethylaminostyryl)-5-(p-diethylaminophenyl)-2
- A coating solution was prepared by kneading 100 parts by weight of pyrazoline (A S P P) and a tetrahydrofuran (THF) solvent in a mixer for 3 hours, and then coated with a wire bar on an aluminum-deposited polyester film (Aff-PET), which is a conductive substrate. A photoreceptor was prepared by coating the photoreceptor by coating the photoreceptor to form a photoreceptor layer having a thickness of 15 μm after drying. .

Example 2 100 parts by weight of tf, p-diethylaminobenzaldehyde diphenylhydrazone (ABPH) and 100 parts by weight of polycarbonate resin (trade name Panlite L-1250, manufactured by Konjin Kasei) were dissolved in methylene chloride. The coating liquid was applied onto an aluminum vapor-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. On the thus obtained charge transport layer, 50 parts by weight of the compound represented by the compound N
A coating solution is prepared by kneading with a time mixer and applied by a wire bar method to form a charge generation layer so that the film thickness after drying is 0.5 μm, and further a coating layer is formed on the charge generation layer.
A photoreceptor was produced.

Example 3 A photoreceptor was produced in the same manner as in Example 2 except that the charge transport material was changed from ABPH to tri(p-tolyl)amine, which is a triphenylamine compound.

Example 4 A coating solution was prepared by kneading 100 parts by weight of the compound represented by Compound No. I-3 with 100 parts by weight of a polyester resin (trade name: Vylon 200, manufactured by Toyobo Co., Ltd.) and MEK solvent for 3 hours using a mixer. It was coated on an aluminum support to a thickness of about 0.5 μm to form a charge generation layer. On top of this, 100 parts by weight of a stilbene compound, α-phenyl-4°-NN-diphenylaminostilbene, and a polycarbonate resin (trade name Panrye) L −
A coating liquid prepared by dissolving 100 parts by weight of 1250) in methylene chloride was applied by a wire bar method to form a charge transport layer, thereby producing a photoreceptor.

Example 5 The charge transport substance in Example 4 was changed to 2,5-bis(p-diethylaminophenyl)-1,3,4-oxadiazole, which is an oxadiazole compound, and the other conditions were the same as in Example 4. A photoreceptor was produced.

The electrophotographic properties of the photoreceptor thus obtained were measured using an electrostatic recording paper tester RSP-428J manufactured by Kawaguchi Electric. The measurement results are shown in Table 1.

The surface potential VS (volt) of the photoreceptor is + or -6 in the dark.
The initial surface potential was obtained when corona discharge of ν was performed for 10 seconds and the surface of the photoreceptor was positively charged in Examples 4 and 3, and negatively charged in Example 4.5, and then the state in which corona discharge was stopped. Measure the surface potential V, (volts) when held in the dark for 2 seconds at
was determined and the half-attenuation exposure amount E, 2 (lux/sec) was determined. 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 1 As seen in Table 1, Examples 1.2.3.4.5 had good half-attenuation exposure and residual potential.

Example 6 100 parts by weight of the compounds represented by the above compounds No. I-4 to No. I-22 and No. If-1 to Nα■-10 were each added to 100 parts by weight of a polyester resin (trade name: Vylon 200, manufactured by Toyobo Co., Ltd.) and a THF solvent for 3 hours to prepare a coating solution.
Each charge generation layer was formed by coating on an aluminum support to a thickness of about 0.5 μm. On top of this, Example 2
A photoreceptor was prepared by applying an ABPH coating solution obtained in the same manner as in the above to a thickness of about 15 μm to form a charge transport layer.

The electrophotographic properties of the photoreceptor thus obtained were measured in the same manner as in Example 4 using an electrostatic recording paper tester rSP-428j manufactured by Kawaguchi Electric. The measurement results for the half-attenuation exposure amount E,/2 are shown in Table 2.

Table 2 (Part 1) Table 2 (Part 2) Table 2 (Part 3) As seen in Table 2, the bisazo compound No.
I-4 to N (LT-22 and No, ll-1
Or N.

(2) Also for the photoreceptor using -10 as a charge generating material, the half-attenuation exposure amount El/. was in good condition.

〔Effect of the invention〕

According to the present invention, since a compound represented by the general formula (I) or (formerly) is used as a charge generating substance on a conductive substrate, a photoreceptor having a photosensitive layer having either a single layer or a laminated structure can be used. It is also possible to obtain a photoreceptor that is positively or negatively charged, has high sensitivity, and has excellent repeatability.Furthermore, if necessary, a coating layer can be provided on the surface to improve durability.

[Brief explanation of the drawing]

FIGS. 1, 2, and 3 are conceptual cross-sectional views showing different embodiments of the photoreceptor of the present invention. 1 conductive substrate, 3 charge generation substance, 4 charge generation layer,
5 charge transport material, 6 charge transport layer, 7 coating layer, 20
．． 21.22-g Photolayer.

Claims (1)

[Scope of Claims] 1) In an electrophotographic photoreceptor comprising a photosensitive layer on a conductive substrate, the photosensitive layer has a charge-generating substance formed by the following general formula (
An electrophotographic photoreceptor comprising at least one of the bisazo compounds represented by I). ▲There are mathematical formulas, chemical formulas, tables, etc.▼...(I) (In formula (I), A represents a coupler residue.) 2) Electrophotographic photoreceptor comprising a photosensitive layer on a conductive substrate A photoreceptor for electrophotography, wherein the photoreceptor layer contains at least one bisazo compound represented by the following general formula (II) as a charge generating substance. ▲There are mathematical formulas, chemical formulas, tables, etc.▼...(II) (In formula (II), A represents a coupler residue.) 3) A (coupler residue) in the above general formula (I) is the following general The electrophotographic photoreceptor according to claim 1, characterized in that it has one of formulas (III) to (VIII). ▲ 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) ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ ( VI) ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ or ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (VII) ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (VIII) [In formulas (III) to (VIII), Z is a residue that is fused with a benzene ring to form an aromatic polycycle or a heterocycle;
X_1 is OR or NR_1, R_2 (R, R_1 and R_2 each represent a hydrogen atom, each of the following optionally substituted alkyl groups, aryl groups, and heterocyclic groups), X_2 and X_5 are the following: represents any one of an optionally substituted alkyl group, aryl group, or heterocyclic group, and X_3 and X_6 are hydrogen atoms, cyano groups, carbamoyl groups, carboxyl groups, ester groups, or acyl groups. , X_4 or X_1_1 is a hydrogen atom, each of the following optionally substituted alkyl groups, cycloalkyl groups, alkenyl groups,
Represents any one of an aralkyl group, an aryl group, and a heterocyclic group; , X_9 represents any of the following optionally substituted alkyl group, aryl group, carboxyl group, or ester group, X_1_0 represents an optionally substituted aryl group or heterocyclic group, and Y is a heterocyclic group. Represents the residues forming the . 4) The electrophotographic photosensitive material according to claim 2, wherein A (coupler residue) in the general formula (B) is one of the general formulas (III) to (VIII). body. 5) The electrophotographic photoreceptor according to any one of claims 1 to 4, wherein the photosensitive layer is a single layer containing a charge-generating substance and a charge-transporting substance. 6) Claims 1 to 4, characterized in that the photosensitive layer comprises a charge generation layer containing a charge generation substance and a charge transport layer containing a charge transport substance laminated thereon. The electrophotographic photoreceptor according to any one of the above. 7) The photosensitive layer comprises a charge transport layer containing a charge transport substance and a charge generation layer containing a charge generation substance laminated thereon. The electrophotographic photoreceptor according to any one of the above.