JPH06202356A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To obtain a photosensitive body having high sensitivity and excellent characteristics for repeated use by using a specified dipyridophenanthroline bisazo compd. in a photosensitive layer. CONSTITUTION:The photosensitive body has a photosensitive layer containing at least one kind of dipyridophenanthroline bisazo compd. expressed by formulae I-III as an electric change producing material. Namely, a photosensitive layer 20 (for a constitution of single-layer photosensitive body) consisting of at least one compd. expressed by formulae I to III and a charge transfer material 5 dispersed in a resin binder on a conductive base body 1. The conductive base body 1 acts as an electrode for the photosensitive body and as a supporting body for other layers. For the base body, a metal such as aluminum, stainless steel, and nickel, or a glass or resin treated to have conductivity may be used. The proportion of the electric change producing material dispersed in the resin binder is 5-95%, and preferably 50-85%.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a charge generating substance used in a photosensitive layer of an electrophotographic photoreceptor.

[0002]

2. Description of the Related Art Conventionally, as a photosensitive material for an electrophotographic photoreceptor (hereinafter also referred to as a photoreceptor), an inorganic photoconductive substance such as selenium or a selenium alloy, or an inorganic photoconductive substance such as zinc oxide or cadmium sulfide is used as a resin. Those dispersed in a binder, organic photoconductive substances such as poly-N-vinylcarbazole or polyvinylanthracene, and organic photoconductive substances such as phthalocyanine compounds or bisazo compounds dispersed in a resin binder And those that are vacuum-deposited are used.

Further, the photoreceptor is required to have a function of retaining surface charges in a dark place, a function of receiving light to generate charges, and a function of receiving light to transport charges as well. Then, a so-called single-layer type photoconductor having these functions together, and a layer having a function separated mainly into a layer that contributes to charge generation and a layer that contributes to retention of surface charge in a dark place and charge transport during light reception. There is a so-called laminated type photoreceptor in which the layers are laminated. For example, the Carlson method is applied to the image formation by the electrophotographic method using these photoconductors. Image formation by this method is charging by corona discharge to a photoconductor in a dark place, formation of an electrostatic latent image such as characters and pictures of an original on the charged surface of the photoconductor, electrostatic latent image formed The toner is used for development, and the developed toner image is fixed on a support such as paper. After the toner image is transferred, the photosensitive member is subjected to static elimination, residual toner removal, and the like, and then reused.

In recent years, a photoconductive organic dye excellent in charge generating ability due to its advantages such as flexibility, thermal stability and film forming property,
Many photoreceptors using pigments have been proposed, for example, U.S. Pat. No. 3,484,237, Japanese Patent Publication No. 60-456.
Various azo compounds are known from JP-A-64, JP-A-60-5941 and the like.

[0005]

As described above, the organic material has many advantages that the inorganic material does not have, but at the same time, an organic material sufficiently satisfying all the characteristics required for the electrophotographic photoreceptor can be obtained. However, there is a problem with the sensitivity and the characteristics during repeated 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 a photosensitive layer, a copy having high sensitivity and excellent repeatability can be obtained. An object is to provide an electrophotographic photoreceptor for machines and printers.

[0006]

In order to achieve the above object, according to the present invention, at least one of the dipyridophenanthroline bisazo compounds represented by the following general formulas (I) to (III) is used as a charge generating substance. An electrophotographic photoreceptor having a photosensitive layer containing the same.

[0007]

[Chemical 5]

[0008]

[Chemical 6]

[0009]

[Chemical 7]

[In the formulas (I) to (III), A represents a coupler group, and R ¹ and R ² represent a hydrogen atom, a halogen atom, an alkyl group or an aryl group. ]

[0011]

There is no known example in which the dipyridophenanthroline bisazo compounds represented by the general formulas (I) to (III) are used in the photosensitive layer. These inventors have conducted various experiments on these bisazo compounds in earnestly examining various organic materials in order to achieve the above-mentioned object, and as a result, their technical elucidation has not been sufficiently conducted. It has been found that the use of a specific bisazo compound represented by any of the general formulas (I) to (III) as a charge generating substance is extremely effective in improving electrophotographic characteristics, and a photoreceptor having high sensitivity and excellent repeating characteristics. Has come to obtain.

[0012]

EXAMPLE The general formula (I) used in the present invention
The dipyridophenanthroline bisazo compound represented by (III) can be synthesized by a usual method. Specific examples of the dipyridophenanthroline bisazo compounds represented by the general formulas (I) to (III) thus obtained are as follows.

[0013]

[Chemical 8]

[0014]

[Chemical 9]

[0015]

[Chemical 10]

The compounds represented by the above general formulas (I) to (III) are prepared by tetrazotizing the corresponding diamino compounds by a conventional method, and then reacting with the corresponding couplers and a suitable solvent (eg, N, N) in the presence of an alkali. It can be easily synthesized by a coupling reaction in dimethylformamide, dimethylsulfoxide, etc.). The photoreceptor of the present invention contains the compounds represented by the general formulas (I) to (III) in the photosensitive layer. It can be used as shown.

FIG. 1 is a sectional view showing a single-layer type photosensitive member according to an embodiment of the present invention, FIG. 2 is a sectional view showing a negatively charged laminated type photosensitive member according to an embodiment of the present invention, and FIG. FIG. 3 is a cross-sectional view showing a positively charged layered type photoreceptor according to the example of FIG. 1 is a conductive substrate, 20, 21 and 22 are photosensitive layers, 3 is a charge generating substance, 4 is a charge generating layer, 5 is a charge transporting substance, 6
Is a charge transport layer, and 7 is a coating layer. FIG. 1 shows the above general formulas (I) to (III) in which a charge generating substance 3 is formed on a conductive substrate 1.
And a charge transporting material 5 dispersed in a resin binder (binder). A photosensitive layer 20 (a structure usually called a single layer type photoreceptor) is provided. . FIG. 2 shows a charge generation layer 4 on a conductive substrate 1 containing at least one of the compounds represented by the general formulas (I) to (III), which is a charge generation substance 3.
And a charge-transporting layer 6 containing a charge-transporting substance 5 are laminated to form a photosensitive layer 21 (which is usually referred to as a laminated photoreceptor). FIG. 3 shows a layer structure opposite to that of FIG. 2. In this case, it is general to further provide a coating layer 7 to protect the charge generation layer 4.

The reason why the two kinds of layer structures shown in FIGS. 2 and 3 are used is that even if the layer structure shown in FIG. 2, which is usually used as a negative charging system, is used in the positive charging system, a charge transporting material suitable for this is used. This is because the layer structure shown in FIG. 3 is required at the present stage as a positive charging type photosensitive member. The photoreceptor of FIG. 1 can be prepared by dispersing a charge generating substance in a solution in which a charge transporting substance and a resin binder are dissolved, and applying this dispersion liquid onto a conductive substrate.

In the photoreceptor of FIG. 2, a dispersion liquid obtained by dispersing particles of a charge generating substance in a solvent or a resin binder is coated on a conductive substrate, dried and the charge transporting substance and the resin binder are dissolved thereon. It can be prepared by applying and drying the prepared solution. The photoreceptor of FIG. 3 is a dispersion obtained by applying a solution in which a charge transporting substance and a resin binder are dissolved onto a conductive substrate, drying the solution, and then dispersing the particles of the charge generating substance onto the solvent or the resin binder. Can be prepared by coating, drying and further forming a coating layer.

The conductive substrate 1 serves not only as an electrode of the photosensitive member but also as a support for each of the other layers, and may be cylindrical, plate-shaped or film-shaped, and is made of aluminum or stainless steel. A metal such as nickel, glass, resin, or the like that has been subjected to a conductive treatment may be used. The charge generation layer 4 is formed by applying a material in which particles of the charge generation substance 3 selected from at least one kind of compounds represented by the general formulas (I) to (III) are dispersed in a resin binder. , Receives light and generates electric charge.
In addition, it is important that the charge generation efficiency is high, and at the same time that the generated charges are injectable into the charge transport layer 6 and the coating layer 7, and that the electric field dependency is small and the injection is good even in a low electric field. The charge generation layer may be mainly composed of a charge generation material and a charge transport material may be added to the charge generation layer. As the resin binder, it is possible to use polycarbonate, polyester, polyamide, polyurethane polyvinyl butyral, epoxy resin, a polymer or copolymer of methacrylic acid ester in an appropriate combination. As a dispersion solvent for the resin binder, ethyl acetate, methyl ethyl ketone, tetrahydrofuran, dichloromethane, dichloroethane, N, N dimethylformamide and the like can be used. The ratio of the charge generation substance dispersed in the resin binder is 5 to 95%, preferably 50 to 95%.
85%.

The charge transport layer 6 is a resin binder containing an organic charge transport material, a hydrazone compound, a pyrazoline compound,
It is formed by applying a material in which a stilbene compound, a triphenylamine compound, an oxazole compound, or an oxadiazole compound is dissolved / dispersed. It retains the electric charge of the photoconductor as an insulating layer in a dark place, and a charge generating layer when receiving light. It exerts the function of transporting electric charges injected from. As the resin binder, polymers, copolymers, etc. of polycarbonate, polyester, polystyrene, methacrylic acid ester and the like can be used.

The coating layer 7 has a function of receiving and holding a charge of corona discharge in a dark place, and also has a property of transmitting the light to which the charge generating layer is sensitive, and transmits the light at the time of exposure,
It is necessary to reach the charge generation layer and receive the injection of the generated charges to neutralize and eliminate the surface charges. As the coating material, an organic insulating film forming material such as polyester or polyamide can be applied. It is also possible to use a mixture of these organic materials with an inorganic material such as glass resin and SiO ₂ , a metal alkoxy compound having a film forming ability, and a material such as a metal and a metal oxide for reducing electric resistance. The coating material is not limited to the organic insulating film forming material, but an inorganic material such as SiO ₂ or a metal,
It is also possible to form a metal oxide or the like by a method such as vapor deposition or sputtering. As described above, it is desirable that the coating material be as transparent as possible in the wavelength region of the maximum light absorption of the charge generating substance. The film thickness of the coating layer itself depends on the mixed composition of the coating layer, but can be arbitrarily set within a range in which there is no adverse effect such as an increase in residual potential when repeatedly and continuously used. Example 1 The compound No. 50 parts by weight of the compound represented by 1 is used as a polyester resin (trade name: Byron 200: manufactured by Toyobo) 10
0 parts by weight and 1-phenyl-3- (p-diethylaminostyryl) -5- (p-diethylaminophenyl) -2-
100 parts by weight of pyrazoline (ASPP) and a solvent of tetrahydrofuran (THF) are kneaded with a mixer for 3 hours to prepare a coating solution, which is coated on an aluminum vapor-deposited polyester film (AL-PET) which is a conductive substrate by a wire bar method. A photoreceptor was prepared so that the film thickness after coating and drying was 20 μm. Example 2 The compound No. 50 parts by weight of the compound shown by 2, polyester resin (trade name: Byron 200: manufactured by Toyobo) 50
The coating solution was prepared by kneading the parts by weight and a THF solvent with a mixer for 3 hours to form a charge generation layer so that the film thickness after drying was 0.5 μm. On the charge generation layer thus obtained, 100 parts by weight of P-diethylaminobenzaldehyde-diphenylhydrazone (ABPH) and 100 parts by weight of a polycarbonate resin (trade name Panlite L-1250: Teijin Chemicals) were dissolved in methylene chloride. The coating solution thus obtained was applied onto an aluminum vapor-deposited polyester film base by a wire bar method to form a charge transport layer so that the film thickness after drying was 20 μm. Example 3 In Example 2, the charge transport material was changed to ABPH,
Using tri (p-tolyl) amine, which is a triphenylamine compound, a charge generation layer was formed in the same manner as in Example 2, and a charge transport layer was further formed to prepare a photoreceptor. Example 4 The compound No. 100 parts by weight of the compound represented by 3 is a polyester resin (trade name: Byron 200: manufactured by Toyobo) 1
A coating solution was prepared by kneading with 100 parts by weight of MEK solvent for 3 hours with a mixer to prepare a coating solution on an aluminum support of about 0.
The charge generation layer was formed by coating so as to have a thickness of 5 μm. On top of this, a stilbene compound, α-phenyl-4 ^, -
100 parts by weight of N, N-diphenylaminostilbene and a polycarbonate resin (trade name: Panlite L-1250:
A coating liquid prepared by dissolving 100 parts by weight of Teijin Chemicals Co., Ltd. in methylene chloride was applied by a wire bar method to form a charge transport layer, thereby preparing a photoreceptor. Example 5 In the same manner as in Example 4, except that the charge transport material in Example 4 was replaced with 2,5-bis (p-diethylaminophenyl) -1,3,4-oxadiazole, which is an oxadiazole compound. A charge generating layer was formed, and then a charge transporting layer was formed to prepare a photoreceptor. Comparative Example 1 In Example 1, the compound No. A photoconductor was prepared in the same manner as in Example 1 except that ε-type copper phthalocyanine was used instead of the bisazo compound of Example 1. Comparative Example 2 In Example 2, the compound No. A photoconductor was prepared in the same manner as in Example 2 except that Chlorodian Blue was used instead of the bisazo compound of Example 2.

The electrophotographic characteristics of the photoconductor thus obtained were measured by the electrostatic recording paper testing apparatus "SP-428" manufactured by Kawaguchi Electric Co., Ltd.
Was measured using. Regarding the surface potential Vs (V) of the photoconductor, in Example 1 and Comparative Example 1, the initial surface potential when the photoconductor surface was positively charged by performing corona discharge of +6.0 kV for 10 seconds in the dark was used. In Examples 2 to 5, Comparative Example 2 and Example 6 described later, the initial surface potential when the surface of the photoreceptor was negatively charged by performing corona discharge of -6.0 kV for 10 seconds in the dark was measured. Is. Then, the surface potential Vd (V) when the corona discharge was stopped and kept in the dark for 2 seconds was measured, and the time until Vd became half by irradiating the photoconductor surface with white light with an illuminance of 2 lx ( s) was obtained and set as a half-attenuated exposure amount E _1/2 (lx · s).
The surface potential when white light with an illuminance of 2 lx was applied for 10 seconds was defined as the residual potential Vr (V). The measurement results are shown in Table 1.

[0024]

[Table 1] As can be seen in Table 1, Examples 1-5 have half-attenuated exposure doses,
The residual potential is good. Example 6 The compound No. 100 parts by weight of the compound represented by 4 to 27 is respectively added to a polyester resin (trade name: Byron 20
0: Toyobo Co., Ltd.) and a THF solvent were kneaded for 3 hours with a mixer to prepare a coating solution, and a charge generation layer was formed so that the film thickness after drying was 0.5 μm. ABP obtained on this by the same method as produced in Example 2
A coating solution of H was applied to a thickness of about 20 μm to prepare a photoconductor.

The electrophotographic characteristics of the photoconductor thus obtained were measured by the electrostatic recording paper testing apparatus "SP-428" manufactured by Kawaguchi Electric Co., Ltd.
Was measured using. The results are shown in Table 2.

[0026]

[Table 2] As seen in Table 2, bisazo compound No. 4-27
The half-attenuated exposure amount and the residual potential are also good for the photoconductor in which is used as the charge generating substance.

[0027]

According to the present invention, since the compounds represented by the general formulas (I) to (III) are used as the charge generating substance on the conductive substrate, the photoreceptor having high sensitivity and excellent repetitive characteristics is obtained. Can be obtained. Further, if necessary, a coating layer may be provided on the surface to improve durability.

[Brief description of drawings]

FIG. 1 is a sectional view showing a single-layer type photoconductor according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a negatively charged laminated type photoreceptor according to an embodiment of the present invention.

FIG. 3 is a cross-sectional view showing a positively charged laminated type photoreceptor according to an embodiment of the present invention.

[Explanation of symbols]

 1 Conductive Substrate 3 Charge Generating Material 4 Charge Generating Layer 5 Charge Transporting Material 6 Charge Transporting Layer 7 Covering Layer 20 Photosensitive Layer 21 Photosensitive Layer 22 Photosensitive Layer

Claims (2)

[Claims] 1. A photosensitive layer is provided on a conductive substrate, and the photosensitive layer contains at least one of the dipyridophenanthroline bisazo compounds represented by the following general formulas (I) to (III) as a charge generating substance. A photoconductor for electrophotography, which is characterized by: [Chemical 1] [Chemical 2] [Chemical 3] [In the formulas (I) to (III), A represents a coupler group, and R ¹ ,
R ² represents a hydrogen atom, a halogen atom, an alkyl group or an aryl group. ] 2. The electrophotographic photoconductor according to claim 1.
And A (coupler residue) of the general formula (I) is
Electrophotography characterized by being represented by general formulas (IV to IX)
Photoconductor. [Chemical 4][In the formulas (IV to IX), Z is condensed with a benzene ring.
A residue forming an aromatic polycycle or a heterocycle, X¹Is hydrogen
Atom or COOR^', CONR^', R^"(R, R^'
And R^"Are a hydrogen atom and an optionally substituted
A alkyl group, an aryl group, or a heterocyclic group), X²Oh
And X^FiveIs an optionally substituted alkyl group, ari
Group or heterocyclic group, X³And X⁶Is hydrogen
Child, cyano group, carbamoyl group, carboxyl group, S
Represents a ter group or an acyl group, X ^FourOr X¹¹Is hydrogen
Child, optionally substituted alkyl group, cycloalkyl group,
Alkenyl, aralkyl, aryl or heterocycle
Represents a group, X⁷And X⁸Are hydrogen atom and halogen
Atom, nitro group, optionally substituted alkyl group or
Represents an alkoxy group, X⁹Is an optionally substituted alkyl
Represents a group, an aryl group, a carboxyl group, an ester group,
X^TenRepresents an optionally substituted aryl group or heterocyclic group.
Y represents a residue forming a heterocycle. ]