JPH01167759A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To obtain the title photosensitive body which has a high sensitivity and excellent repetitive characteristics by providing a photosensitive layer contg. at least one kind among specific disazo compds. therein. CONSTITUTION:This photosensitive body is constituted by having the photosensitive layer contg. at least one kind among the disazo compds. expressed by the formula I. In the formula I, -D- denotes any of the structures expressed by the formulas II-IV; Cp denotes a residual coupler group. In the formulas II-IV, Y1-Y18 denote a hydrogen atom, cyano group, carbamoyl group, carboxyl group, ester group, acyl group, halogen atom, sulfonic acid group, alkyl group which may be substd., cycloalkyl group, alkenyl group, aryl group or arom. heterocyclic group; Ar denotes an arom. hydrocarbon group or arom. heterocyclic group which may be substituted. The photosensitive body having the high sensitivity and the excellent repetitive characteristics is thereby obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an electrophotographic photoreceptor, and more specifically, in a photosensitive layer formed on a conductive substrate, a compound represented by the general formula (I) is added. The present invention relates to an electrophotographic photoreceptor containing a disazo compound.

[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 disazo compounds, or dispersion of these organic photoconductive materials in a resin binder. Those that have been made are 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, poly-N-vinylcarbazole and 2.
4.7-'iJ nitrofluoren-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
3), and a photoreceptor whose main component is a eutectic complex consisting of a dye and a resin (described in JP-A-47-10735). Furthermore, many new azo compounds and perylene compounds have 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 including a photosensitive layer containing at least one type of disazo compound represented by the following general formula (r).

cp-N=N-D-N=N-Cp -(I) [In formula (I), -D- represents any of the following structures (II) to (IV), and Cp is Coupler residues are shown.

1(■) (Formula (II) ~ (I'l/) where Y, ~Y, . is a hydrogen atom, a cyano group, a carbamoyl group, a carboxyl group,
Ester group, acyl group, halogen atom, 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 Ar represents an optionally substituted aromatic hydrocarbon group or an aromatic heterocyclic group. )] Furthermore, it is preferable that the coupler residue Cp in the general Monna 1) has any of the following structures - Monna (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,
OR, or HNR2R, (R, Rz and R5 represent a hydrogen atom, an alkyl group, an optionally substituted aryl group or an aromatic heterocyclic group), x2 and Xs may each be substituted represents an alkyl group, an aryl group or an aromatic heterocyclic group, X3 and x6 are hydrogen atoms,
represents a cyano group, a carbamoyl group, a carboxyl group, an ester group, or an acyl group, and x4 represents a hydrogen atom, an optionally W-substituted alkyl group, a cycloalkyl group, an alkenyl group, an aryl group, or an aromatic heterocyclic group; ,X,
and Xs 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 XIO represents an optionally substituted aryl group or an aromatic heterocyclic group.

] [Function] There is no known example in which the disazo compound represented by the above-mentioned -Momona (I) 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. We have discovered that the use of a specific disazo compound represented by the above-mentioned pattern (I) 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 above-mentioned disazo compound (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 the above-mentioned -Momonena (I) thus obtained are as follows.

2 z
zII
II 11
z z
zII
II 11 The photoreceptor of the present invention contains the disazo compound represented by the above-mentioned pattern (I) in the photosensitive layer. Or the third
It can be used as shown in the figure.

FIGS. 1 to 3 are conceptual cross-sectional views of different embodiments of the photoreceptor of the present invention, where l 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 a photoreceptor with the layer configuration shown in Figure 2 is used for positive charging, there are currently no compatible charge transport materials. This is because it has not been found. 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 l functions 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 metal such as aluminum, stainless steel, or nickel. 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 disazo compound shown by the symbol (I) are dispersed in a resin binder, and receives light to generate charges. Occur. In addition, it is important that the charge generation efficiency is high and that the generated charges are injected into the charge transport layer 6 and the coating layer 7, 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, 5
It is also possible to use a mixture of inorganic materials such as i02 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 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.

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) with a tetrahydrofuran (THF) solvent in a mixer for 3 hours, and then coated with a wire bar on an aluminum-deposited polyester film (Aj!-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 *F,p-diethylaminobenzaldehyde-diphenylhydrazone (A, BPH) 100 parts by weight dissolved in 700 parts by weight of tetrahydrofuran (THF) and polycarbonate resin (Panlite L-1250) 100 parts by weight were dissolved in THF and dichloromethane. 1:1 mixed solvent with 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.

On the charge transport layer thus obtained, the compound N
50 parts by weight of the disazo compound represented by a 1, 50 parts by weight of polyester resin (trade name: Vylon 200, manufactured by Toyobo), 50 parts by weight of PMMA, and a THF solvent were kneaded in a mixer for 3 hours to prepare a coating solution, and then applied to the wire bar method. A charge generation layer was formed so that the film thickness after drying was 0.5 μm, and a photoreceptor having the structure shown in FIG. 3 was prepared. 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 V, kuvolt of the photoreceptor is +6. Ok
This is the initial surface potential when corona discharge of V is performed for 10 seconds to positively charge the surface of the photoreceptor, and then the surface potential is V when held in the dark for 2 seconds with corona discharge stopped.
Measure a (volts), then irradiate the surface of the photoreceptor with white light with an illuminance of 2 lux, find the time (seconds) until V becomes half, and calculate the half-attenuation exposure amount Eke 2 (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 vr (volt).

As shown in Table 1, the photoreceptors of Examples 1, 2, and 3°4.5 had good surface potential v, half-attenuation exposure area El/2+residual potential Vr.

Example 6 100 parts of the disazo compounds represented by the above compounds Nα2 to Nα75 were mixed with 100 parts by weight of a polyester resin (trade name: Vylon 200) and a THF solvent.
A coating solution was prepared by kneading with a time mixer, and the coating solution was coated on an aluminum support to a thickness of about 0.5 μm to form a charge generation layer. 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.

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 maintained in the dark for 2 seconds with corona discharge stopped, and then white light with an illuminance of 2 lux was irradiated onto the surface of the photoreceptor. The time it takes for V to be halved (seconds)
was determined and set as the half-attenuation exposure amount E172 (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, (volts).

Table 2 (Part 1) Table 2 (Part 2) Table 2 (Part 3) Table 2 (Part II) As seen in Table 2, the compounds Na2 to Nα7
The photoreceptor using No. 5 also had a half-attenuation exposure amount of E+/2.

Both residual potential Vr is good.

〔Effect of the invention〕

According to the present invention, since the disazo compound represented by the above-mentioned pattern (I) is used as a charge generating substance on a conductive substrate, a photosensitive material with high sensitivity and excellent repeatability even in positive and negative charging can be obtained. You can get a body.

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 sectional views showing different embodiments of the photoreceptor of the present invention. l conductive substrate, 2a, 2b, ``lc photosensitive layer,
3: charge generating substance; 4: charge generating layer; 5: charge transporting substance; 6: charge transporting layer; 7: coating layer. Figure 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)
[In formula (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, Ar
represents an optionally substituted aromatic hydrocarbon group or aromatic heterocyclic group. )]2) The photoreceptor according to claim 1, characterized in that Cp in the general formula (I) is a disazo compound having a structure of any one of the following general formulas (V) to (VIII). A photoreceptor for electrophotography. ▲ 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) ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ ( 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,
is OR_1 or NR_2R_3(R_1, R_2
and R_3 represents a hydrogen atom, an alkyl group, an optionally substituted aryl group, or an aromatic heterocyclic group),
2 and X_5 each represent an optionally substituted alkyl group, aryl group or aromatic heterocyclic group, and X_3
and X_6 is a hydrogen atom, a cyano group, a carbamoyl group,
Represents a carboxyl group, ester group or acyl group, X
_4 represents a hydrogen atom, an optionally substituted alkyl group, cycloalkyl group, alkenyl group, aryl group, or aromatic heterocyclic group, and X_7 and X_8 each represent a hydrogen atom, a halogen atom, a nitro group, or a substituted represents an optionally alkyl group or alkoxy group, and X_9
represents an alkyl group, an aryl group, a carboxyl group, and
_1_0 represents an optionally substituted aryl group or aromatic heterocyclic group. ]