JPH06161135A - Electrophotographic photosensitive body - Google Patents

Abstract

PURPOSE:To provide an organic photosensitive body in stability, durability and especially in potential stability at the time of repeated continuous use. CONSTITUTION:A photosensitive body is provided with a laminated photosensitive layer formed by laminating a charge generating layer and a charge transport layer in this order on a conductive base body through an under-coating layer. The charge generating layer is formed of binder resin containing charge generating material, and a charge transport layer is formed of binder resin containing a hydrazone compound expressed by a formula I as charge transport material and a benzidine compound expressed by a formula II. In the formula I, R1 represents an aryl group, R2 represents an alkyl group or the like of 1-3 in the number of hydrogen atoms or carbon atoms, and Ar represents condensed polycyclic aromatic hydrocarbon. In the formula II, Z1 represents an alkyl group of 1-2 in the number of hydrogen atoms or carbon atoms, and Z2 and Z3 represent either an alkyl group of 1-2 in the number of hydrogen atoms or carbon atoms, or a halogen atom.

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, and more particularly to an electrophotographic photosensitive member which is made of an organic material and is excellent in stability and durability, especially in stability of potential during repeated and continuous use.

[0002]

2. Description of the Related Art Conventionally, as an electrophotographic photoreceptor (hereinafter also simply referred to as a photoreceptor), an inorganic photoreceptor using an inorganic photoconductive substance such as selenium, a selenium alloy, zinc oxide or cadmium sulfide as a photosensitive material. Has been widely used. On the other hand, focusing on advantages such as flexibility, thermal stability, film forming property, and low price, an organic photoconductor made of an organic material using an organic photoconductive material has been developed and put into practical use. . For example, poly-N-vinylcarbazole and 2,4
A photoreceptor containing 7-trinitrofluoren-9-one (US Pat. No. 3,484,237), a photoreceptor containing an organic pigment as a main component (JP-A-47-37543), and a eutectic complex containing a dye and a resin are used. Photoreceptor containing main component (Japanese Patent Publication No. 47-
No. 10735). Such an organic photoreceptor is
Although it has many advantages, it has not been widely used because it is inferior to inorganic photoconductors in terms of sensitivity and durability, but in recent years, photoconductors with excellent chargeability and sensitivity have been developed and rapidly spread. I'm doing it.

[0003]

The photoconductor is repeatedly used in the electrophotographic image forming process, and is required to have stable photoconductor characteristics at all times. However, with respect to such stability and durability, the present situation is that organic photoreceptors have not yet fully met the demands of the market. That is, with repeated use, the potential drops, the residual potential rises,
There is a problem that the sensitivity of the image is changed, the quality of the output image and the print quality are deteriorated, and the image cannot be used.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems and to provide an organic photoreceptor having excellent stability and durability, especially stability of potential during repeated continuous use. .

[0005]

According to the present invention, at least one of the hydrazone compounds represented by the following general formula (I) and the benzidine compound represented by the following general formula (III) can be solved. The problem is solved by using a photoreceptor having a photosensitive layer containing at least one kind as a charge transport material.

Further, the above-mentioned problem is that at least one kind of hydrazone compounds represented by the following general formula (II) and at least one kind of benzidine compounds represented by the following general formula (III) are contained as charge transport substances. The problem can also be solved by using a photoreceptor having a photosensitive layer.

[0007]

[Chemical 4]

[0008]

[Chemical 5]

[In the formulas (I) and (II), R1 represents an aryl group which may have a substituent, and R2 represents a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, or a halogen atom. Represents either. R3, R4 and R5 are each a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxyl group, a hydroxy group, a nitro group or an allyl group, an aryl group which may have a substituent or an aralkyl group. It represents either, a _r represents a substituted condensed polycyclic aromatic hydrocarbon may have a substituent. ]

[0010]

[Chemical 6]

[In the formula (III), Z1 represents a hydrogen atom or an alkyl group having 1 to 2 carbon atoms. Z2 and Z3 each represent a hydrogen atom, an alkyl group having 1 to 2 carbon atoms, or a halogen atom. ]

[0012]

The hydrazone compound represented by the general formula (I) as a charge transport substance and the benzidine compound represented by the general formula (III) are mixed and used, or the hydrazine compound represented by the general formula (II) is used. By using the hydrazone compound represented by the above formula and the benzidine compound represented by the general formula (III) in a mixture, stability, durability, particularly in continuous use, can be improved as compared with the case where each compound is used alone. It is possible to obtain a photoreceptor having excellent potential stability.

[0013]

EXAMPLES Specific examples of the hydrazone compounds represented by the general formulas (I) and (II) are shown below.

[0014]

[Chemical 7]

[0015]

[Chemical 8]

[0016]

[Chemical 9]

Specific examples of the benzidine compound represented by the general formula (III) are shown below.

[0018]

[Chemical 10]

The photoconductor of the present invention comprises a mixture of at least one of these hydrazone compounds and at least one of benzidine compounds as a charge transporting substance in the photosensitive layer. Figure 1
There are two types shown in FIG.

FIG. 1 is a conceptual cross-sectional view of an embodiment of the photoconductor of the present invention, in which a binder resin containing a charge generating substance 21 is formed on a conductive substrate 1 via an undercoat layer 3. Separate charge-generating layer 22, and a charge-transporting layer 24 made of a binder resin containing a hydrazone compound as a charge-transporting substance 23 and a benzidine compound are sequentially laminated. Is. The photoreceptor having this structure is usually used in a negative charging system.

FIG. 2 is a conceptual cross-sectional view of a different embodiment of the photoconductor of the present invention. Hydrazone as a charge generating substance 21 and a charge transporting substance 23 on a conductive substrate 1 via an undercoat layer 3. A single-layer type photoreceptor provided with a single-layer photosensitive layer 2b made of a binder resin containing a compound and a benzidine compound. The undercoat layer 3 in FIGS. 1 and 2
Is provided as necessary and may be omitted.

The conductive substrate 1 serves not only as an electrode of the photoconductor but also as a support for each of the other layers, such as aluminum, aluminum alloy, stainless steel, or the like, which has conductivity, or glass or resin. The surface of which is subjected to a conductive treatment is used. The subbing layer 3 is provided between the conductive substrate and the photosensitive layer and has a function of enhancing the barrier function and the adhesiveness of the carrier, and is provided as necessary. Casein, polyvinyl alcohol, polyvinyl methyl ether, It can be formed of poly-N-vinylimidazole, ethyl cellulose, ethylene-acrylic acid copolymer, phenol resin, polyamide, polyurethane, gelatin, aluminum oxide and the like. The thickness of the undercoat layer is preferably 0.05 μm to 20 μm, and particularly preferably 0.05 μm to 10 μm.

The charge generating layer 22 is prepared by dispersing the charge generating substance 21 in a solvent together with 0.3 to 2 times the amount of the binder resin by a method such as a homogenizer, ultrasonic wave, ball mill, sand mill, paint shaker. It is formed by applying the dispersion and drying. The film thickness is 0.01
The range of μm to 3 μm, particularly 0.05 μm to 1 μm is preferable. As the charge generating substance, metal-free phthalocyanine,
Phthalocyanine compounds such as titanyl phthalocyanine,
Pigments such as various azo, quinone and indigo, dyes such as cyanine, squarylium, azurenium and pyrylium compounds, selenium and selenium compounds are used, and a suitable substance is selected and used according to the wavelength region of exposure light. As the binder resin, polyvinyl butyral, polyarylate, polycarbonate, polyester, phenoxy resin, polyvinyl acetate, epoxy resin, acrylic resin, polyacrylamide resin, polyamide, polyvinyl pyridine, cellulose, urethane resin, casein, polyvinyl alcohol, polyvinyl Resins such as pyrrolidone may be mentioned. As the solvent, alcohols such as methanol, ethanol and isopropyl alcohol,
Acetone, methyl ethyl ketone, ketones such as cyclohexanone, N, N-dimethylformamide, N, N-
Amides such as dimethylacetamide, ethers such as tetrahydrofuran, dioxane, ethylene glycol dimethyl ether, dimethoxyethane and propylene oxide, esters such as methyl acetate, ethyl acetate and dimethyl carbonate, chloroform, dichloromethane,
Aliphatic hydrogen halides such as dichloroethylene and trichloroethylene, or aromatics such as benzene, toluene, xylene and monochlorobenzene can be used.

The charge transport layer 24 is formed by dissolving the above-mentioned hydrazone compound and benzidine compound as the charge transport substance 23 in a solvent together with a suitable binder resin as necessary, applying the solution and drying. To be done.
The film thickness is preferably 10 μm to 50 μm, and particularly preferably 15 μm to 40 μm. The total amount of the hydrazone compound and the benzidine compound in the charge transport layer is 30% by weight to 70% by weight, particularly 40% by weight to 60% by weight based on the total solid content in the charge transport layer.
A weight% range is preferred. The mixing ratio of the hydrazone compound and the benzidine compound is 5: 95-9 by weight.
It is 5: 5, preferably 60:40 to 20:80. Examples of the binder resin that can be used include acrylic resin, polyarylate, polyester, polycarbonate, polystyrene, acrylonitrile-styrene copolymer, polyvinyl butyral, polyvinyl formal, polyacrylamide, and polyamide. The solvent used may be the same as that used for the charge generation layer.

The single-layer photosensitive layer 2b shown in FIG.
1 and a mixture of a hydrazone compound and a benzidine compound as the charge transport material 23 in an amount of 1 to 2 to 10 times the amount thereof are dissolved and dispersed in a suitable solvent together with a suitable binder resin,
It is formed by applying the liquid and drying. The film thickness is preferably 10 μm to 40 μm, and particularly preferably 15 μm to 25 μm.

Specific examples of the present invention will be described below, but the present invention is not limited to the following examples. The parts in the examples are parts by weight. Example 1 30 mm long, 30 mm wide, and 1 mm thick as a conductive substrate
The aluminum plate of was prepared. A coating solution prepared by dissolving 4.5 parts of polyamide (Amylan CM8000, manufactured by Toray Industries, Inc.) in 150 parts of methanol was dip-coated on this plate and dried at a temperature of 90 ° C. for 20 minutes to obtain a film thickness of 0.2 μm. A pulling layer was provided.

Next, 2 parts of a disazo pigment represented by the following structural formula as a charge generating substance, 2 parts of a polyester resin (manufactured by Toyobo Co., Ltd .; Byron 200), and cyclohexanone 9 are used.
0 parts were mixed and dispersed with a sand grinder for 6 hours.
60 parts of tetrahydrofuran was added to this dispersion to dilute it to obtain a coating solution, which was then dip coated on the undercoat layer and dried at a temperature of 90 ° C. for 20 minutes to form a charge generation layer having a thickness of 0.4 μm. .

[0028]

[Chemical 11]

Subsequently, the above compound No. as a charge transporting substance was used. 5 parts of the hydrazone compound 5 and the compound N
o. 17 parts of benzidine compound of 17 together with 3 parts of bisphenol Z type polycarbonate resin (number average molecular weight of 50,000) was dissolved in 30 parts of tetrahydrofuran to prepare a coating solution, and the solution was coated on the charge generation layer with a wire bar. It was dried at a temperature of 100 ° C. for 20 minutes to form a charge transport layer having a film thickness of 20 μm, and a laminated type photoreceptor having the structure shown in FIG. 1 was produced.

Example 2 In Example 1, the compound N as a charge transport material was used.
o. Compound No. 5 instead of the hydrazone compound of No.
Example 1 except that the 11 hydrazone compound was used.
A photoconductor was prepared in the same manner as in. Example 3 In Example 1, the compound N as a charge transport material is used.
o. Instead of the benzidine compound of 17, the compound N
o. A photoconductor was produced in the same manner as in Example 1 except that 20 of the benzidine compounds was used.

Example 4 In Example 1, the compound N as a charge transport material was used.
o. Compound No. 5 instead of the hydrazone compound of No.
The hydrazone compound of No. 11 was used as the compound No. Compound No. 17 instead of the benzidine compound of No. 17 A photoconductor was produced in the same manner as in Example 1 except that 20 of the benzidine compounds was used.

Comparative Example 1 In Example 1, the above compound N was used as the charge transport material.
o. 5 parts of the hydrazone compound of 5 and the compound No.
Instead of using 1.5 parts of the benzidine compound of No. 17, the compound No. A photoconductor was prepared in the same manner as in Example 1 except that 3 parts of the hydrazone compound of 5 was used.

Comparative Example 2 In Example 1, the compound N was used as the charge transport material.
o. 5 parts of the hydrazone compound of 5 and the compound No.
Instead of using 1.5 parts of the benzidine compound of No. 17, the compound No. A photoconductor was prepared in the same manner as in Example 1 except that 3 parts of the benzidine compound of 17 was used.

Regarding the photoconductor thus produced,
The sensitivity was evaluated, and further, as the repetitive characteristics, changes in the charged potential and the residual potential when the charging, the exposure and the static elimination were repeated were examined. For these measurements, an electrostatic charging test device EPA8100 manufactured by Kawaguchi Electric Co., Ltd. was used. In the dark place, the surface of the photoconductor is charged by corona discharge at −6 kV for 10 seconds, then exposed by white light with an illuminance of 2lux, and the surface potential is attenuated to half of the initial level, which is the half-attenuation. The sensitivity was evaluated by _{obtaining the} exposure dose E _1/2 (E _1/2
The smaller the value of, the better the sensitivity). Next, a repeating process in which charging, exposure, and static elimination were set as one cycle was repeated 5000 cycles, and the charged potential and the residual potential before and after that were measured. As the residual potential, the surface potential after irradiation of white light with an illuminance of 2lux for 10 seconds was defined as the residual potential. The results of these measurements are shown in Table 1.

[0035]

[Table 1]

As can be seen from Table 1, in the function-separated layered type photoreceptor, as the charge transport material of the charge transport layer,
The photoconductor of Comparative Example 1 using the hydrazone compound alone showed a large increase in the residual potential by repetition, and the photoconductor of Comparative Example 2 using the benzidine compound alone showed a large decrease in the charged position by the repetition. In each of the photoconductors of Examples 1 to 4 in which the benzidine compound and the benzidine compound were used as a mixture, the charge potential and the residual potential due to the repetition were stable, and the effect of mixing the two as a charge transport material is clear. Is.

Example 5 As a conductive substrate, as in Example 1, the length is 30 mm and the width is 30.
An aluminum plate having a thickness of 1 mm and a thickness of 1 mm was prepared. On top of this, polyamide (manufactured by Teijin Chemical Co., Ltd .; Toresin MF-
30) A solution prepared by dissolving 4.5 parts in 150 parts of methanol is applied by dipping and dried at a temperature of 90 ° C. for 20 minutes to give a film thickness of 0.2 μm.
m undercoat layer was provided. Next, the compound No. as a charge transporting substance. 2 parts of the hydrazone compound of No. 2 and the compound No. 18 parts of benzidine compound (1.5 parts) and 4.5 parts of polyvinyl butyral resin (manufactured by Sekisui Chemical Co., Ltd .; Eslec BX-2) as a binder resin were dissolved in 60 parts of dichloromethane and used as a charge generating substance. 0.5 part of X-type metal-free phthalocyanine was added and dispersed in a ball mill for 20 hours. This dispersion is applied onto the above-mentioned undercoat layer with a wire bar and dried at a temperature of 100 ° C. for 20 minutes to form a photosensitive layer having a film thickness of 20 μm, and a single-layer type photosensitive film having the structure shown in FIG. 2 is formed. The body was made.

Example 6 In Example 5, the compound N as a charge transport material was used.
o. Compound No. 2 instead of the hydrazone compound of No. 2
A photoconductor was produced in the same manner as in Example 5 except that the hydrazone compound of 9 was used. Example 7 In Example 5, the compound N as a charge transport material is used.
o. Instead of the benzidine compound of 18, the compound N
o. A photoconductor was produced in the same manner as in Example 5 except that the benzidine compound of 19 was used.

Example 8 In Example 5, the compound N as the charge transport material was used.
o. Compound No. 2 instead of the hydrazone compound of No. 2
The hydrazone compound of No. 9 was used, and the compound No. 18 instead of the benzidine compound of No. 18 A photoconductor was produced in the same manner as in Example 5 except that the benzidine compound of 19 was used.

Comparative Example 3 In Example 5, the compound N was used as the charge transport material.
o. 2 parts of the hydrazone compound of No. 2 and the compound No.
18 instead of using 1.5 parts of the benzidine compound. A photoconductor was prepared in the same manner as in Example 5, except that 3 parts of the hydrazone compound of 2 was used.

Comparative Example 4 In Example 5, the above compound N was used as the charge transport material.
o. 2 parts of the hydrazone compound of No. 2 and the compound No.
18 instead of using 1.5 parts of the benzidine compound. A photoconductor was prepared in the same manner as in Example 5, except that 3 parts of the benzidine compound of 18 was used.

With respect to the photoconductor thus obtained,
The sensitivity was evaluated in the same manner as in Example 1 except that the corona discharge voltage was changed to +6 kV, and the repetitive characteristics were the charge potential and residual potential when charging, exposure, and charge elimination were repeated. I examined the fluctuations. The results are shown in Table 2.

[0043]

[Table 2]

As shown in Table 2, even in the single-layer type photoconductor, in the photoconductor of Comparative Example 3 in which the hydrazone compound was used alone as the charge transport material of the photoconductor layer, the residual potential was increased by repetition. In the photoconductor of Comparative Example 4 in which the benzidine compound was used alone, the charge position was largely decreased by repetition, but in the photoconductors of Examples 5 to 8 in which the hydrazone compound and the benzidine compound were mixed, The charge potential and residual potential are stable due to repetition, and the effect of using both as a charge transport material in a mixture is clear.

[0045]

According to the present invention, at least one kind of the hydrazone compounds represented by the general formula (I) and at least one kind of the benzidine compounds represented by the general formula (III) are used as the charge transport material. A photoconductor having a photosensitive layer containing. Alternatively, a photosensitive layer provided with a photosensitive layer containing at least one kind of the hydrazone compound represented by the general formula (II) and at least one kind of the benzidine compound represented by the general formula (III) as a charge transport substance. The body. In this way, by using both of them as the charge transporting material, it is possible to obtain a photosensitive member having stability and durability, especially stable potential during repeated and continuous use.

[Brief description of drawings]

FIG. 1 is a conceptual sectional view of an embodiment of a photoconductor of the present invention.

FIG. 2 is a conceptual sectional view of a different embodiment of the photoconductor of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Conductive substrate 2a Laminated photosensitive layer 2b Single photosensitive layer 3 Undercoat layer 21 Charge generating substance 22 Charge generating layer 23 Charge transporting substance 24 Charge transporting layer

Claims (2)

[Claims] 1. A photosensitive layer comprising, as a charge-transporting substance, at least one kind of hydrazone compounds represented by the following general formula (I) and at least one kind of benzidine compounds represented by the following general formula (III). An electrophotographic photoreceptor characterized by being provided. 2. A photosensitive layer comprising, as a charge-transporting substance, at least one kind of hydrazone compounds represented by the following general formula (II) and at least one kind of benzidine compounds represented by the following general formula (III). An electrophotographic photoreceptor characterized by being provided. [Chemical 1] [Chemical 2] [In the formulas (I) and (II), R1 represents an aryl group which may have a substituent, and R2 represents a hydrogen atom or a carbon atom number of 1 to 3.
Represents an alkyl group or a halogen atom. R3, R4 and R5 are each a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxyl group, a hydroxy group, a nitro group or an allyl group, an aryl group which may have a substituent or an aralkyl group. Represents either
A _r represents a condensed polycyclic aromatic hydrocarbon which may have a substituent. ] [Chemical 3] [In Formula (III), Z1 represents a hydrogen atom or a carbon atom of 1
~ Represents 2 alkyl groups. Z2 and Z3 each represent a hydrogen atom, an alkyl group having 1 to 2 carbon atoms, or a halogen atom. ]