JPS63183451A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To improve the sensitivity and repetitive characteristics of a sensitive body by using an azo compd. contg. a trithienylamine structure as an electric charge generating substance. CONSTITUTION:An electric charge generating layer 4 contg. one or more kinds of azo compds. each contg. a trithienylamine structure represented by formula I, II or III as an electric charge generating substance and an electric charge transferring layer 6 contg. a hydrazone compd. or the like are successively laminated on an electrically conductive substrate 1. In the formulae I-III, each of R1-R14 is H, halogen or the like, A is a coupler residue and each of (l), (m) and (n) is 0-6. The layers 6, 4 and a coating layer 7 may be successively laminated on the substrate 1. A single layer may be formed as a photosensitive layer in place of a laminate type photosensitive layer 21, 22. A sensitive body having high sensitivity whether positively or negatively charged and also having superior repetitive characteristics is obtd. by using the azo compds.

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 having the general formula (1),
The present invention relates to an electrophotographic photoreceptor containing an azo compound represented by (I[) or (III).

[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-vinyl carbazole or polyvinyl anthracene, phthalocyanine compounds or bisazo compounds, or these organic photoconductive materials in a resin binder. Dispersed materials are used.

In addition, a photoreceptor must 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 one layer. A so-called single-layer type photoreceptor that has both functions, and a so-called laminated layer 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 laminated 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 the latent image with toner, transferring the developed toner image to a support such as paper, and fixing it. After the toner image is transferred, the photoreceptor is charged, the residual toner is removed,
After photostatic charge removal, etc., it is reused.

In recent years, due to its advantages such as flexibility, thermal stability, and film-forming properties,
Electrophotographic photoreceptors using organic materials are being put into practical use. For example, poly-N-vinyl carbazole 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 hydrazone compounds have also been put into practical use.

[Problem that the invention seeks to solve]

However, although organic materials have many advantages that inorganic materials do not have, it is currently not possible to obtain a material that satisfactorily satisfies all the characteristics required of an electrophotographic photoreceptor, especially in terms of photosensitivity and There were problems with the characteristics when used repeatedly and continuously.

The present invention has been made in view of two points,
An object of the present invention is to provide an electrophotographic photoreceptor with 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.

[Failure to solve the problem]

According to the present invention, at least one azo compound containing a trichenylamine structure represented by the following general formula (I), (II) or (III) is For electrophotography having a photosensitive layer containing (formula (I)
), (II) and (III), R1 to RI4 are each a hydrogen atom, a halogen atom, or a hydroxy group.

Alkyl group, alkoxy group, allyl group, aldehyde group,
Acyl group, carboxyl group, ester group.

Carbamoyl group, amine group, alkylamino group.

Arylamino group, aryl group, aralkyl group.

It represents a nitro group or a cyano group, and A represents a coupler residue. Also, β1m and n are 0°1.2, 3, respectively.
Represents an integer value of 4.5 or 6. ) [Function] There is no known example in which an azo compound represented by the above general formula (1), (II) or (III) is used in a photosensitive layer.

In order to achieve the above object, the present inventors have carried out numerous experiments on these azo compounds while conducting intensive studies on various organic materials, and have found that, although their technical clarification has not yet been fully elucidated, It has been discovered that the use of a specific azo compound represented by the above-mentioned general formula (1), (II) or (III) as a charge generating substance is extremely effective in improving electrophotographic properties. As a result, we were able to obtain a photoreceptor with excellent repeatability.

〔Example〕

The azo compounds of the general formulas (I), (n) and (I[[) used in the present invention are prepared by combining the corresponding diazonium salt and coupler in a suitable organic solvent such as N.

It can be synthesized by reacting with a base in N-dimethylformamide (DMF) to cause a coupling reaction.

Specific examples of the azo compounds of the general formulas (1), (II) and (II) thus obtained are as follows. The values of β1m and n are shown in Tables 2 and 3, respectively.
Table 4 shows the results.

Compound No. 8-14 No. 15-21 No. 22-28 Compound No. 29-35 No. 36-42 No. 43-49 Compound No. 50-56 No. 57-63 Compound No. 71-77 No. 78 -84 Compound No, 92-98 No, 99-105 No, 106-112 Compound No, 113-119 No, 120-126 Compound Nα134-14O Nα141-147 No, 148-154 Compound No, 155-161 Compound No, 197-203 Compound No. 239-245 No. 274-280 The photoreceptor of the present invention contains an azo compound represented by the general formula (I), (II) or (III) in the photosensitive layer. However, depending on the application of these azo compounds, they can be used as shown in FIG. 1, FIG. 2, or FIG. 3.

1 to 3 are conceptual cross-sectional views of different embodiments of the photoreceptor of the present invention, where ■ is a conductive substrate, 20, 21.2
2 is a photosensitive layer, 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 an azo compound as a charge-generating substance 3 and a charge-transporting substance 5 on a conductive substrate 1 using a resin binder (binder).
A photosensitive layer 20 (commonly referred to as a single-layer photoreceptor) is provided therein.

FIG. 2 shows a photosensitive layer 21 consisting of a stack of a charge-generating layer 4 containing an azo compound as a charge-generating substance 3 and a charge-transporting layer 6 mainly composed of a charge-transporting substance 5 on a conductive substrate l.
(a configuration commonly referred to as a laminated photoreceptor).

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

In this case, a coating layer 7 is generally provided to protect the charge generation layer 4, and the photosensitive layer 22 is a charge transport layer 6.
．． Charge generation layer 4. It is composed of a covering layer 7.

The reason for the two types of layer configurations shown in FIGS. 2 and 3 is that the photoreceptor is used in a positive charging system or a negative charging system, and the layer configuration shown in FIG. 2 is usually used in a negative charging system. Even if you try to use the positive charging method with the layer configuration shown in Figure 2,
At present, no charge-transporting substance has been found that meets this requirement. Therefore, as the present inventors have already proposed, the layer structure shown in Figure 3 is considered to be effective as a positive charging type photoreceptor. It can be mentioned.

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. It can be produced by applying a dispersion, drying it, and further forming a coating layer thereon.

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 has general formulas (I), (II) and (I
It is formed by applying a material in which particles of a charge generating substance 3 made of an azo compound represented by II> are dispersed in a resin binder, and generates charges by receiving light. 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. As the resin binder, polycarbonate, polyester, polyamide, polyurethane, epoxy, silicone resin, polymers and copolymers of methacrylic acid ester, etc. can be used in appropriate combinations.

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 the resin binder, polycarbonate, polyester, polyamide, polyurethane, epoxy, silicone resin, polymers and copolymers of methacrylic acid ester, 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, 81
It is also possible to use a mixture of inorganic materials such as 02 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 SiO□, 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 azo compound represented by Compound No. 1 was mixed with 100 parts by weight of a polyester resin (Vylon manufactured by Toyobo) and 1-phenyl-3-(P-diethylaminostyryl)-5-(para-diethylaminophenyl)- 2-pyrazoline (ASPP>100 parts by weight and tetrahydrofuran (
A coating solution was prepared by kneading with a THF) solvent in a mixer for 3 hours, and the coating solution was coated on an aluminum-deposited polyester film (8β-PET), which is a conductive substrate, using a wire bar method, and the film thickness after drying was determined. A photosensitive layer was formed to have a thickness of 15 μm, and a photosensitive member having the structure shown in FIG. 1 was produced.

Example 2.3 In Example 1, the azo compounds represented by Compound No. 1 and Compound No. 99. No,
197, and the rest was the same as Example 1.
Photoreceptors of Examples 2 and 3 were produced in the same manner as described above.

Example 4 First, a solution of P-diethylaminobenzaldehyde-diphenylhydrazone (ABPH>100 parts by weight dissolved in 700 parts by weight of tetrahydrofuran (THF) and 100 parts by weight of polycarbonate resin (Panlite L-1250) was mixed with THF and dichloromethane. 1:1 mixed solvent 70
A coating solution prepared by mixing 0 parts by weight of the solution was applied onto an aluminum-deposited polyester film substrate using a wire bar to form a charge transport layer so that the film thickness after drying was 15 μm.

The above compound No.
, 50 parts by weight of an azo compound represented by I, 50 parts by weight of polyester resin (trade name Byron 200; manufactured by Toyobo),
A coating solution was prepared by kneading 50 parts by weight of PMMA and a THF solvent in a mixer for 3 hours, and coating with a wire bar to form a charge generation layer so that the film thickness after drying was 0.5 μm. A photoreceptor corresponding to the configuration shown in was fabricated. However, a coating layer not directly related to the present invention was not provided.

Example 5.6 In Example 4, the azo compounds represented by Compound No. 1 were replaced with Compound No. 99, .
Photoreceptors of Examples 5 and 6 were produced in the same manner as in Example 4 except that the azo compound shown by No. 197 was used.

Examples 7, 8.9 In Example 4.5.6, the charge transporting substance was ABP.
Instead of H, a styryl compound, α-phenyl-4
Photoreceptors of Examples 7 and 8.9 were prepared in the same manner as in Examples 4 and 5.6 except that ``-N,N-dimethylaminostilbene was used.

Example 10.11.12 In Examples 4 and 5.6, the charge transport substance was ABP
Instead of H, a triphenylamine compound,
(p-tolyl)amine was used, and the rest was as in Examples 4 and 5.
Example 10.11°12 photoreceptors were prepared in the same manner as in Example 6.

Example 13.14.15 In Examples 4 and 5.6, the charge transporting substance was ABP
Instead of H, 2.5- which is an oxadiazole compound
Photoreceptors of Examples 13, 14 and 15 were prepared in the same manner as in Examples 4 and 5.6 except that bis(p-diethylaminophenyl)-1,3,4-oxadiazole was used.

The electrophotographic properties of the photoreceptor thus obtained were measured using an electrostatic recording paper tester RSP-428J manufactured by Kawaguchi Electric.

The surface potential V, (volt) of the photoreceptor is +6, OkV 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 Vd is then maintained in the dark for 2 seconds with corona discharge stopped.
(volts), and then the illuminance 2 on the photoreceptor surface.
Calculate the time (seconds) it takes for V to be halved after irradiating the lux white light, and find the half-attenuation exposure amount E1/2 (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 V (volt).

Measurement Table 1 As seen in Table 1, the compounds No. 1,
N.

The photoreceptors of Examples 1 to 15 in which the azo compound represented by No. 99 or No. 197 was used as a charge generating substance had a surface potential Vs, a half-attenuation exposure amount E l/2 + a residual potential Vr.
Both were good.

Example 16 100 parts by weight of the azo compounds represented by Compounds No. 2 to No. 98 were kneaded together with 100 parts by weight of polyester resin (trade name: Vylon 200) and a THF solvent for 3 hours in a mixer to prepare a coating solution. , and were coated on an aluminum support to a thickness of about 0.5 μm to form a charge generation layer. On top of this, apply approximately 15μ of the ASPP coating solution obtained in the same manner as in Example 4.
A photoreceptor having the structure shown in FIG.

The electrophotographic properties of the photoreceptor thus obtained were measured using an electrostatic recording paper tester RSP-428J manufactured by Kawaguchi Electric. Among the results, the half-attenuation exposure amount and residual potential are shown in Table 2.

The surface potential vS (volt) of the photoreceptor is -6, OkV in the dark.
This is the initial surface potential when corona discharge is performed for 10 seconds to negatively charge the surface of the photoreceptor, and then the surface potential is V when the corona discharge is stopped and the surface is held in the dark for 2 seconds.
Measure d (volts), and then irradiate the surface of the photoreceptor with white light with an illuminance of 2 lux to find the time (seconds) until Vd is halved, which is the half-attenuation exposure amount El/2 (lux seconds). 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 (volts).

Table 2 (Part 1) Table 2 (Part 2) Table 2 (Part 3) Table 2 (Part 4) Table 2 (Part 5) Table 2 (Part 6) Table 2 (Part 7) As seen in Table 2, said compounds No. 2-N.

The photoreceptor of Example 16 using the azo compound represented by 98 as the charge generating substance had a half-attenuation exposure amount E, 2. Both residual potential vr were good.

Example 17 In Example 16, the compounds No. 2 to No. 9
The azo compounds represented by No. 8 and No. 1 are respectively
A photoreceptor was prepared in the same manner as in Example 16 except that the azo compounds represented by 00 to Nα196 were used, and the electrophotographic characteristics were measured. Among them, the measurement results of the half-attenuation exposure amount and residual potential are shown in Table 3.

Table 3 (Part 1) Table 3 (Part 2) Table 3 (Part 3) Table 3 (Part 4) Table 3 (Part 5) Table 3 (Part 6) As seen in Table 3 , said compound No. 100~N
The photoreceptor of Example 17 using the azo compound represented by o, 196 as the charge generating substance also had a half-attenuation exposure amount Bl/2.
+residual potential Vr were both good.

Example 1B In Example 16, the compounds No. 2 to No. 9
The azo compounds represented by No. 8 and No. 1 are respectively
Photoreceptors were prepared in the same manner as in Example 16, except that the azo compounds represented by No. 98 to No. 294 were used, and the electrophotographic properties were measured. Table 4 shows the measurement results for half-attenuation exposure and residual potential.

Table 4 (Part 1) Table 4 (Part 2) Table 4 (Part 3) Table 4 (Part 4) Table 4 (Part 5) Table 4 (Part 6) Table 4 (Part 7) As seen in Table 4, the compounds No. 198-
The photoreceptor of Example 18 in which the azo compound shown by No. 294 was used as a charge generating substance also had a half-attenuation exposure amount B+/
2+ residual potential Vr were both good.

〔Effect of the invention〕

According to the present invention, the general formula (I), (II) or (D
Since the azo compound represented by I) is used, it is possible to obtain a photoreceptor with high sensitivity and excellent repeatability even in positive and negative charging. Furthermore, if necessary, it is possible to provide a coating layer on the surface to improve durability.

[Brief explanation of the drawing]

1.2 and 3 are conceptual 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 substance, 6 charge transport layer, 7 coating layer, 2
0.21.22 Photosensitive layer. Figure 1 ? Figure Conductive/Semi-substrate Figure 3

Claims (1)

[Scope of Claims] 1) It is characterized by having a photosensitive layer containing at least one type of azo compound containing a trithienylamine structure represented by the following general formula (I), (II) or (III). A photoreceptor for electrophotography. ▲There are mathematical formulas, chemical formulas, tables, etc.▼………………(I) ▲There are mathematical formulas, chemical formulas, tables, etc.▼……………………(II) ▲There are mathematical formulas, chemical formulas, tables, etc.▼………… ...(III) (In formulas (I), (II) and (III), R_1 to R_
1_4 are hydrogen atoms, halogen atoms, hydroxy groups, alkyl groups, alkoxy groups, allyl groups, aldehyde groups, acyl groups, carboxyl groups, ester groups, carbamoyl groups, amino groups, alkylamino groups, arylamino groups, aryl groups, respectively. It represents an aralkyl group, a nitro group or a cyano group, and A represents a coupler residue. Further, l, m and n each represent an integer value of 0, 1, 2, 3, 4, 5 or 6. )