JPH05289376A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To prevent the light fatigue of a photosensitive body by repeating use and the ascending of residual potential by combining a specific bisazo compound with an amine derivative. CONSTITUTION:A photosensitive layer containing the bisazo compound high in the generation efficiency of charge and expressed by a formula I as a charge generating agent and the diamine compound high in hole transfer efficiency and expressed by a formula II as a charge transfer agent is provided. In the formula I, X is hydrogen, a halogen atom, alkyl group and an alkoxyl group, Y is a group composed of -CONH-Ar, -CONHN-Ar, Ar is an aromatic carbon cyclic group or an aromatic heterocyclic group possible to have substituted group. In the formula II, X' is hydrogen, an alkyl group, alkoxyl group, each of R1-R4 is hydrogen, an alkyl group, alkoxyl group.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic photosensitive member provided with a photosensitive layer containing, as an essential component, two kinds of organic materials of a specific bisazo compound and a specific diamine derivative.

[0002]

2. Description of the Related Art Conventionally, inorganic materials such as selenium, selenium tellurium, diarsenic triselenide, cadmium sulfide, zinc oxide, and amorphous silicon have been generally used as photoconductive materials for electrophotographic photoreceptors. However, these photoconductors have drawbacks such as poor flexibility in practical use, being sensitive to heat and mechanical impact, and being high in manufacturing cost. In recent years, a photoreceptor using an organic material that eliminates these drawbacks has been proposed and put into practical use. This organic photoreceptor is a so-called function-separated type in which a charge generation layer and a charge transfer layer are generally laminated on a conductive support, and a photosensitive layer which also serves as the two layers is laminated on the conductive support. The function-combined type is widely known.

As the function-separated type, for example, a photosensitive layer in which a charge generation layer containing a cyanine pigment or the like as an active ingredient and a charge transfer layer containing an organic compound such as hydrazone type, pyrazoline type or oxadiazole type are laminated. The body is well known, and it is known that many compounds are effective as both the charge generating agent and the charge transfer agent.

In such a function-separated type photoreceptor, the charge generator absorbs light in the charge generation layer to generate carriers, and the generated carriers are injected into the charge transfer layer and move in the charge transfer layer. However, it is important to select a material that allows the charge generator to move to the surface without being trapped by impurities in the transfer layer. The electrophotographic characteristics of the above-mentioned function-separated type electrophotographic photosensitive member are greatly influenced by the combination of the charge generating agent and the charge transfer agent.

However, when many compounds are used as a photosensitive layer in combination with a charge generation layer and a charge transfer layer, it has been experimentally found that very few compounds satisfy the various characteristics and conditions of the photoreceptor required for practical use. Known as a result. In particular, there are few that satisfy the repeating characteristics of charging and exposure by the known electrophotographic process, and repeated charging and exposure causes an increase in residual potential, which is considered to be caused by accumulation of traps of charge generators in the charge transfer layer. Fogging is likely to occur in the image. It is assumed that these are due to light fatigue. The above-mentioned problems also occur in a single-layer photoconductor having a function and a function in which a phthalocyanine pigment, a bisazo pigment or the like is dispersed and coated on a binder resin.

[0006]

DISCLOSURE OF THE INVENTION The inventors of the present invention have earnestly studied and conducted experiments on a method for preventing light fatigue of a photoconductor due to repeated use and a rise in residual potential accompanying it. As a result, the compound of the general formula [I
It has been found that the combination of the specific diamine derivatives represented by V] has extremely excellent characteristics as a photoreceptor for electrophotography, and has solved the above-mentioned problems.

[0007]

The present invention is directed to a bisazo compound represented by the following general formula [I] having a high charge generation efficiency as a charge generating agent and a general formula [I] having a high hole transfer efficiency as a charge transfer agent. IV] is provided with a photosensitive layer containing a diamine derivative represented by IV as an essential component.

[Chemical 6] (In the formula, X represents a hydrogen atom, a halogen atom, an alkyl group or an alkoxy group. Y represents a group consisting of -CONH-Ar [II] -CONHN = CH-Ar [III], and Ar has a substituent. Which may be an aromatic carbocyclic group or an aromatic heterocyclic group)

[Chemical 7] (In the formula, X'is hydrogen, an alkyl group, an alkoxy group, R
_{1 to} R ₄ represent hydrogen, an alkyl group or an alkoxy group. )

That is, by containing the above two components, efficient generation of electric charges and migration of holes with respect to incident light occur, and it has been confirmed that the organic photoconductor has excellent characteristics, and it has been completed. Is.

The charge generation layer used in the present invention has a first characteristic in that it contains a bisazo pigment represented by the following general formula [I].

[Chemical 8] (In the formula, X represents a hydrogen atom, a halogen atom, an alkyl group, or an alkoxy group. Y represents a group consisting of -CONH-Ar [II] -CONHN = CH-Ar [III], and Ar has a substituent. Which may be an aromatic carbocyclic group or an aromatic heterocyclic group)

Specific examples of the bisazo compound used in the present invention are shown in Table 1.

[Table 1]

This charge generation layer can be formed by means of coating or the like with a dispersion liquid in which the aforementioned pigment is dispersed in a binder solution. As the binder, for example, polyvinyl butyral, polyvinyl acetal, polyester, polycarbonate, polyamide, polyurethane, phenol resin or the like can be used. The resin forming these binders accounts for 8% in the charge generation layer.
It is preferably 0% or less, preferably 50% or less, and particularly preferably 40% or less. As the solvent, alcohols, ethers such as dioxane, cyclohexanone and tetrahydrofuran, ketones such as acetone and methyl ethyl ketone, and chlorine hydrocarbons such as dichloromethane, chloroform and carbon tetrachloride can be used. The solid content concentration of the bisazo compound and the binder in the solvent is preferably 0.5 to 5%, more preferably 1 to 3%. Further, the ratio of the bisazo compound and the binder is 0.5 / 1 to 5/1,
Desirably, 1/1 to 3/1 is preferable.

When the above-mentioned pigment is dispersed, the bisazo compound and the binder are dried, kneaded and pulverized by a known method using a ball mill, an attritor or the like, and then continuously mixed with a solvent by using a dispersing device such as a sand mill. It is obtained by dispersing. As the dispersion method in which the pigment is dispersed in this way and the coating method used when the charge transfer layer described below is provided,
It is applied by a coating method such as a blade coating method, a Meyer bar coating method, a spray coating method, a dip coating method, a curtain coating method or a bead coating method. The film thickness of the charge generation layer is 5 μm or less, preferably 0.1 to 2 μ.

Another feature of the present invention is to use a charge transfer layer containing a specific diamine derivative, that is, a diamine derivative represented by the following general formula [IV], for a charge generation layer using a bisazo pigment. is there.

[Chemical 9] (In the formula, X'is hydrogen, an alkyl group, an alkoxy group, R
_{1 to} R ₄ represent hydrogen, an alkyl group or an alkoxy group. )

Specific examples of the diamine derivative represented by the general formula [IV] used in the present invention are shown in Table 2 below.

[Table 2]

The charge transfer layer used in the present invention has the general formula [I
V] is preferably formed by coating a solution prepared by dissolving a diamine derivative represented by V] and a binder in an appropriate solvent and drying.

The binder and the solvent can be selected in the same manner as the above-mentioned coating liquid of the bisazo compound. The ratio of the diamine derivative to the binder in the solvent is 0.3 / 1 to 2/1, preferably 0.5 / 1 to 1.5 / 1. The thickness of the charge transfer layer is 5 to 30 μm, preferably 15 to 25 μm.
Is desirable.

The charge transfer layer of the present invention may contain various additives. For example, 2-tert-butyl-4-methoxyphenol, 2,6-di-tert-
Butylphenol, 2,6-di-tert-butyl-4
-Methylphenol, 2,6-di-tert-butyl-
Examples include phenolic antioxidants such as 4-ethylphenol and 2,6-di-tert-butyl-4-butylphenol. These phenolic antioxidants suppress the occurrence of cracks due to the adhesion of oil, fingerprints, etc. to the surface of the photoconductor without impairing the basic properties of the photoconductor, and have ozone resistance and stability of the coating liquid. Along with the improvement, the repeating characteristics and light fatigue characteristics of the electrophotographic photosensitive member are improved. In particular, a phenolic antioxidant having a molecular weight of 200 to 1000 is effective, and is effective against 1 of the diamine derivative in the coating liquid.
It is desirable to dissolve ~ 20 wt% antioxidant.
When the content is 1% by weight or less, cracks occur, and when the content is 20% by weight or more, the residual potential increases.

Further, the charge transfer layer of the present invention may contain one or more electron-accepting substances. Examples of the electron accepting substance include compounds of the following formulas [V]-(1) to [V]-(3).

[Chemical 10] (In the formula, X ₁ and Y ₁ represent an alkyl group, an alkoxy group or an alkylamino group.)

[Chemical 11] (In the formula, X ₂ and Y ₂ represent an alkyl group or an alkoxy group.)

[Chemical 12] (In the formula, X ₃ and Y ₃ represent an alkyl group or an alkoxy group.) The amount of the electron-accepting substance is 3% by weight or less, preferably 0.2 to 2% by weight based on the charge transfer agent in the charge transfer layer. %.

Various forms of the laminated structure of the electrophotographic photosensitive member are known, and the electrophotographic photosensitive member of the present invention can take any of these forms. 1, 2 and 3 are cross-sectional views of an electrophotographic photoreceptor applied to the present invention. FIG. 1 shows the electroconductive support 1 side with the above-mentioned bisazo compound. FIG. 2 shows a negative charge type function separation type two-layer structure in which a charge generation layer 2 containing a main component and a charge transfer layer 3 containing a diamine derivative as a main component are formed on the charge generation layer 2.
3 shows a positively charged function-separated two-layer structure having an inverse layer structure of FIG. 1, and FIG. 3 shows a bipolar single layer having a photosensitive layer 6 in which a charge generating agent 4 and a charge transfer agent 5 are mixed and dispersed. It shows the structure.

In the photoreceptor of the present invention, further, the charge of the photosensitive layer is prevented from being injected into the photosensitive layer from the conductive support when the photosensitive layer is charged, and the photosensitive layer is integrally bonded to the conductive support. To obtain the function as an adhesive layer to hold it,
If necessary, an intermediate layer 7 may be provided on the conductive support as shown in FIGS. This intermediate layer is made of aluminum oxide, indium oxide, tin oxide, polyethylene,
Acrylic resin, epoxy resin, polycarbonate, polyurethane, vinyl chloride resin, vinyl acetate resin, polyvinyl alcohol, polyamide resin and the like can be used alone or in combination. The thickness of the intermediate layer or the adhesive layer is 0.1 to 5 μm, preferably 0.5 to 3 μm.

The support used in the electrophotographic photosensitive member of the present invention may be any support as long as it has conductivity. Specific examples include metals such as aluminum, copper, stainless steel and brass, and plastics obtained by vapor deposition or lamination of tin oxide and the like. The shape thereof may be a sheet shape, a belt shape, a drum shape, or any other shape.

[0022]

The present invention will be described in more detail by way of examples, which should not be construed as limiting the invention.

Example 1 A bisazo compound [I]-(3) exemplified in Table 1 and polyvinyl butyral were dry-kneaded at a ratio of 2/1 on an aluminum drum substrate, and then dioxane and acetone 8/2 were mixed in a sand mill. Was used as a solvent and was dispersed at a solid content of 10% for 10 hours to obtain a coating liquid A, which was applied by a dip coating method and dried to form a charge generation layer. The film thickness at this time was 0.3 μm. Next, the diamine derivative [IV]-(1) exemplified in Table 2 above.
And polycarbonate are dissolved in dichloromethane at a ratio of 1/1 to obtain a solid content of 25%, and an antioxidant 2,6-di-tert. 10 wt% of -butyl-4-methylphenol was dissolved in each diamine derivative, and the solution was applied as a coating liquid B on the charge generation layer by a dip coating method and dried to form a charge transfer layer. The film thickness at this time was 21 μm.

The photoreceptor thus produced was subjected to corona discharge of -5 kv. The surface potential at this time was measured (initial potential V ₀ ). Further, the surface potential of this photosensitive member after being left for 10 seconds in a dark place was measured, and (V ₁₀ ) V ₁₀ / V ₀ was obtained, which was defined as dark decay DDR. The sensitivity was evaluated by measuring the exposure amount (T / 2, lux · sec) required to attenuate the surface potential −700V to ½. At this time, a halogen lamp (wavelength 780 nm) was used as a light source. The results are shown in Table 3.

Example 2 Instead of the bisazo compound [I] formula- (1) used in Example 1, [I]-(2) shown in Table 1 was used.
A photoconductor was prepared in the same manner as in Example 1 except that the above was used, and the photographic characteristics were measured in the same manner as in Example 1.

Example 3 Except that the diamine derivative [IV]-(1) shown in Table 2 was used in place of the diamine derivative [IV]-(1) shown above used in Example 1, there was no difference. A photoconductor was prepared by the same method, and the photographic characteristics were measured by the same method as in Example 1.

Example 4 On the aluminum drum substrate, 5 of the following polyamide resin (Torayzin F30 manufactured by Teikoku Kagaku Sangyo) was used.
After coating by the μm dip coating method to provide an intermediate layer, a photoreceptor was prepared by the same method as in Example 1, and photographic characteristics were measured by the same method as in Example 1.

[Chemical 13]

Example 5 In the diamine derivative [IV]-(1) exemplified above used in Example 1, X ₂ in the formula [V]-(2) was tert. A photoconductor was prepared by the same method except that 1% of an electron-accepting substance having a butyl group and Y ₂ being a methyl group was added, and the photographic characteristics were measured by the same method as in Example 1.

Comparative Example 1 In place of the diamine derivative [IV]-(1) used in Example 1, the known charge transfer agent compound NO. A photoconductor was prepared in exactly the same manner except that 1 was used.

Comparative Example 2 In place of the diamine derivative [IV]-(1) used in Example 1, a known charge transfer agent compound NO. A photoconductor was prepared by the same method except that No. 3 was used.

Comparative Example 3 In place of the diamine derivative [IV]-(1) used in Example 1, the known charge transfer agent compound NO. A photoconductor was prepared in exactly the same manner except that 5 was used.

Comparative Example 4 In place of the diamine derivative [IV]-(1) used in Example 1, the known charge transfer agent compound NO. A photoconductor was prepared in exactly the same manner except that No. 7 was used.

Comparative Example 5 Additive 2 used in Example 1
6-di-tert. A photoconductor was prepared in exactly the same manner except that -butyl-4-methylphenol was removed.
The photographic characteristics of Examples 1 to 5 and Comparative Examples 1 to 5 are shown in Table 3 above.

[0034]

[Table 3] V ₀ : Surface potential (−5 kv) DDR: Dark decay (surface potential measurement value after the photoconductor is left in the dark for 10 seconds.) VR: Residual potential (charging / erasing is repeated while irradiating white light of 300 Lux, 100 cycles). T / 2: Half-exposure amount (exposure amount necessary for attenuating surface potential -700V to 1/2.) Crack: Oil, fingerprints, etc. adhered to the surface of the photoreceptor, 48
Visually observe after a lapse of time. )

[0035]

[Table 4]

[0036]

[Table 5]

[0037]

As shown in Table 3, the electrophotographic photoconductors of Comparative Examples 1 to 5 have low sensitivity and high residual potential, whereas the electrophotographic photoconductors of Examples 1 to 5 have high sensitivity. The body is
It was found that all of them had high sensitivity and low residual potential.
In addition, the photoreceptor provided with the intermediate layer of Example 4 has an effect of eliminating image defects such as fog and black spots in the reversal phenomenon and improving image quality. In addition, the photoconductor in which the electron-accepting substance is added to the charge transfer layer of Example 5 has a characteristic that light fatigue does not occur without lowering the sensitivity.

The high sensitivity of the electrophotographic photosensitive members of Examples 1 to 5 is considered to be due to the following reasons. Generally, when the organic electrophotographic photosensitive member is divided, it can be classified into a single layer type and a laminated type as described above, but in the case of the single layer type, light is absorbed in the entire photosensitive layer to generate a carrier pair (hole and electron), The charge is attenuated by reaching the separated and opposing electrodes under an electric field. In the case of the laminated type of this embodiment, the functions of the charge generation layer and the charge transfer layer are separated. When light is absorbed in the charge generation layer, a carrier pair is generated, and under negative electric charge, holes are injected into the charge transfer layer in the case of negative charging and move in the charge transfer layer to attenuate the charge. Therefore, it is considered that the interface (energy barrier) with the charge generation layer when holes are injected into the charge transfer agent [IV] of Examples 1 to 5 is extremely small, and therefore the hole injection efficiency is good. ..

The electrophotographic photosensitive member of the present invention has the above-mentioned constitution, and as is apparent from the above-mentioned embodiments, it effectively suppresses light fatigue, has stable repeating characteristics, and has a high photosensitivity. It is expensive. That is, charging characteristics, sensitivity characteristics,
It can be said that the present invention is extremely useful because it has excellent image characteristics, has little fatigue deterioration even after repeated use, and has excellent durability.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an example of an electrophotographic photosensitive member applied to the present invention, showing a negative charging type function separation type two-layer structure.

FIG. 2 is a cross-sectional view showing another example of a photoconductor for electrophotography applied to the present invention, showing a positive charging type function separation type two-layer structure.

FIG. 3 is a cross-sectional view showing another example of an electrophotographic photoreceptor applied to the present invention, which shows a bipolar single-layer structure.

FIG. 4 is a cross-sectional view of another example of an electrophotographic photoreceptor applied to the present invention, in which an intermediate layer is provided between the structure shown in FIG. 1 and a conductive support.

FIG. 5 is a cross-sectional view of another example of the electrophotographic photoreceptor applied to the present invention, in which an intermediate layer is provided between the structure shown in FIG. 2 and the conductive support.

FIG. 6 is a cross-sectional view of another example of the electrophotographic photoreceptor applied to the present invention, in which an intermediate layer is provided between the structure shown in FIG. 3 and the conductive support.

[Explanation of symbols]

 1. Conductive support 2. Charge generation layer 3. Charge transfer layer 4. Charge generating agent 5. Charge transfer agent 6. Photosensitive layer (photoconductive layer)

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Internal reference number FI Technical indication location G03G 5/14 101 D 6956-2H E 6956-2H (72) Inventor Watanabe Yoichi Yamanashi Higashiyatsushiro 287 Terao, Sakaigawa Village

Claims (6)

[Claims] 1. An organic electrophotographic photoreceptor having a photosensitive layer provided on a conductive support, is exposed to a bisazo compound represented by the following general formula [I] and a diamine derivative represented by the following general formula [IV]. An electrophotographic photoreceptor, which is contained in a layer. [Chemical 1] (In the formula, X represents a hydrogen atom, a halogen atom, an alkyl group, or an alkoxy group. Y represents a group consisting of -CONH-Ar [II] -CONHN = CH-Ar [III], and Ar has a substituent. And optionally represents an aromatic carbocyclic group or an aromatic heterocyclic group.) (In the formula, X'is hydrogen, an alkyl group, an alkoxy group, R
_{1 to} R ₄ represent hydrogen, an alkyl group or an alkoxy group. ) 2. The electrophotographic photoreceptor according to claim 1, wherein the photosensitive layer contains 1 to 20% by weight of a phenolic antioxidant based on the diamine derivative represented by the general formula [IV]. 3. The electrophotographic photosensitive member according to claim 1, which has an intermediate layer between the conductive support and the photosensitive layer. 4. The intermediate layer is selected from the group consisting of aluminum oxide, indium oxide, tin oxide, polyethylene, acrylic resin, epoxy resin, polycarbonate, polyurethane, vinyl chloride resin, vinyl acetate resin, polyvinyl alcohol and polyamide resin. The electrophotographic photosensitive member according to claim 3, which contains one or more compounds. 5. The photosensitive layer contains a charge transfer agent and an electron accepting substance, and the content of the electron accepting substance is 3 with respect to the charge transferring agent.
The electrophotographic photosensitive member according to claim 1, wherein the electrophotographic photosensitive member is less than or equal to wt%. 6. The electron-accepting substance is represented by the following general formula [V] -1.
6. The electrophotographic photosensitive member according to claim 5, which is one or more compounds selected from the group consisting of [V] -3. [Chemical 3] (In the formula, X ₁ and Y ₁ represent an alkyl group, an alkoxy group or an alkylamino group.) (In the formula, X ₂ and Y ₂ represent an alkyl group or an alkoxy group.) (In the formula, X ₃ and Y ₃ represent an alkyl group or an alkoxy group.)