JPH0348254A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To obtain the electrophotographic sensitive body having a sufficient sensitivity and good durability by incorporating a specific hydrazone compd. into the photosensitive layer on a conductive base. CONSTITUTION:The hydrazone compd. expressed by formula I is incorporated into the photosensitive layer 4 on the conductive base 1. In the formula I, R1, R2 are an aryl group which may be substd.; R1 and R2 may be combined directly or via a combination group with each other; R3 denotes a hydrogen atom, halogen atom, alkyl group or phenyl group which may be substd.; R4, R5 denote an alkyl group, aralkyl group or aryl group which may be substd.; at least one of which is an aryl group which may be substd. The electrophotographic sensitive body which has the high sensitivity, is not deteriorated in performance in spite of repetitive use and has the excellent performance is obtd. in this way.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a photoreceptor for electrophotography. More specifically, it relates to an electrophotographic photoreceptor characterized in that the photoreceptor layer on a conductive support contains a novel hydrazone compound as a charge transporting substance. [Prior Art] Conventionally, inorganic photosensitive materials such as selenium, cadmium sulfide, and zinc oxide have been widely used as photosensitive materials for electrophotographic photoreceptors. However, photoreceptors using these photosensitive materials do not fully satisfy the performance requirements for electrophotographic photoreceptors, such as sensitivity, photostability, moisture resistance, and durability. For example, a photoreceptor using a selenium-based material has excellent sensitivity, but it tends to crystallize due to heat or adhesion of dirt, and the characteristics of the photoreceptor deteriorate. In addition, it has many drawbacks, such as high cost because it is manufactured by vacuum evaporation, and difficulty in processing it into a belt shape because it is not flexible. Photoreceptors using cadmium sulfide-based materials had problems with moisture resistance and durability, and photoreceptors using zinc oxide had problems with durability. In order to overcome the drawbacks of photoreceptors using inorganic photosensitive materials, various photoreceptors using organic photosensitive materials have been investigated. In recent years, among photoreceptors developed to improve the above-mentioned drawbacks, functionally separated photoreceptors, in which the charge generation function and charge transport function are divided into separate materials, have been attracting attention. In this function-separated photoreceptor, materials with each function can be selected from a wide range of materials and combined, making it possible to produce a highly sensitive and highly durable photoreceptor. The electrophotographic properties required of a charge transport material are (I) a sufficiently high ability to accept the charge generated by the charge generation material, (2) the ability to rapidly transport the accepted charge, and (3) the ability to transport the charge even in a low electric field. These include ensuring sufficient charge transport and not leaving any residual charge. Furthermore, it is used as a photoreceptor for charging, exposing, and
It is required to be stable against light, heat, etc. during the repeated development and transfer processes, and to be durable enough to produce reproduced images that are faithful to the original. Various compounds have been proposed as charge transport materials. For example, poly-N-vinylcarbazole has long been known as a photoconductive material, and products using it as a charge transport material have been put into practical use, but it itself has poor flexibility, is brittle, and easily cracks. Therefore, it had poor durability against repeated use. Furthermore, when it is used in combination with a binder to improve flexibility, it has the disadvantage of poor electrophotographic properties. On the other hand, since low-molecular-weight compounds generally do not have film properties, they are usually mixed with a binder in an arbitrary composition to form a photosensitive layer. Many charge transport materials have been proposed as low molecular weight compounds. For example, hydrazone compounds have high sensitivity as charge transport substances, and
61, JP-A-55-52064, JP-A-57-581
No. 56, JP-A No. 57-58157, etc. However, there are problems with decomposition due to ozone generated during corona charging, and stability against light and heat.Although the initial performance is excellent, repeated use causes a decrease in charge retention ability or accumulation of residual potential, resulting in contrast The result was an image with a decrease in color or a lot of fog. Although many other charge transport materials have been proposed, the current situation is that none of them sufficiently satisfies the required performance as a photoreceptor for electrophotography in practice, and the development of an even better photoreceptor has been desired. ．． [Problems to be Solved by the Invention] An object of the present invention is to provide an electrophotographic photoreceptor having sufficient sensitivity and good durability, and to provide a novel charge transport material for use therein. That's true. [Means for Solving the Problems] In order to solve the above problems, the present inventors have made extensive studies and as a result, the general formula (I) (I) (wherein R1 and R! are diconverted and R, and R2 may be bonded directly or through a linking group, and R is a hydrogen atom, a halogen atom, an alkyl group, or an optionally substituted phenyl group.
R4 and R are an alkyl group, an aralkyl group, or an optionally substituted aryl group, and at least one of them is an optionally substituted aryl group. The present inventors have discovered that a novel hydrazone compound represented by the following formula provides an electrophotographic photoreceptor having excellent properties such as high sensitivity and high durability, leading to the present invention. That is, the present invention
The photosensitive layer on the conductive support has the general formula (I) (I) (wherein R. and R8 are optionally substituted aryl groups, and R. and R8 are bonded directly or through a linking group). and R is a hydrogen atom, a halogen atom, an alkyl group or an optionally substituted phenyl group,
R4 and R are an alkyl group, an aralkyl group, or an optionally substituted aryl group, and at least one of them is an optionally substituted aryl group. ) This is an electrophotographic photoreceptor characterized by containing a hydrazone compound represented by: R1 and R! of the general formula (I) above! Examples of the aryl group include a phenyl group and a naphthyl group, and when the aryl group has two substituents, the substituents include an alkyl group such as a methyl group and an ethyl group, an alkoxy group such as a methoxy group and an ethoxy group, Examples include halogen atoms such as chlorine and bromine atoms, and dialkylamino groups such as dimethylamino and diethylamino groups. R1 and tri are directly or via a linking group R. and R! Examples of the aromatic ring formed with the carbon atom to which m is bonded include fluorene, ananthene, thioxanthene, etc. Examples of the halogen atom of R3 include chlorine atom and bromine atom, and examples of the alkyl group include methyl group and ethyl group. Examples include linear or branched probyl groups, butyl groups, octyl groups, etc., and when R is a phenyl group having a substituent, the substituents include an alkyl group such as a methyl group or an ethyl group, a methoxy group, Examples include alkoxy groups such as ethoxy groups, halogen atoms such as chlorine atoms and bromine atoms, and dialkylamino groups such as dimethylamino and jetylamino groups. R
In 4 and R, the alkyl group includes a methyl group, ethyl group, a linear or branched probyl group, a pentyl group,
Examples of the aralkyl group include a hexyl group and an octyl group; examples of the aralkyl group include a benzyl group, phenethyl group, and naphthylmethyl group; examples of the aryl group include a phenyl group and a naphthyl group; In the case of an aryl group, the substituent is an alkyl group such as a methyl group or an ethyl group, an alkoxy group such as a methoxy group or an ethoxy group, a halogen atom such as a chlorine atom or a bromine atom, or a dialkyl group such as a dimethylamino group or a diethylamino group. An example is an amino group. More specific compounds that can be used in the present invention are shown in Table 1, but the compounds that can be used in the present invention are not limited thereto.

Among the compounds exemplified in Table 1, the exemplified compounds Hiroshi 1, Ai 2, N
115, 13, etc. are preferred.

In addition, an alkyl group, an alkoxy group,
Compounds having substituents such as halogen atoms also have good performance as charge transport materials, but are not industrially advantageous in terms of cost.

Table 1 (Continued) The hydrazone compounds represented by the general formula (I) can be combined as follows, for example. General formula (It) (wherein, R
1.R. and R are the same as R, R8 and R in general formula (I). ) and a hydrazine compound represented by the general formula (III) R4 (wherein, R4 and R are the same as R4 and t's in the general formula (I)) in a suitable solvent. It can be easily obtained by reacting in The hydrazine compound of general formula (III) is used in equimolar or slightly excess amount relative to the aldehyde, preferably from 1.0 to
Use a molar ratio of 1.2. Hydrazine compounds can also be used in the form of mineral acid salts such as hydrochloride. Solvents used include alcohols such as methanol, ethanol, methylcellosolve, and ethylcellosolve;
Examples include ethers such as tetrahydrofuran and 1,4-dioxane, glycols such as ethylene glycol and propylene glycol, N,N-dimethylformamide, dimethyl sulfoxide, and acetic acid. There is no particular restriction on the amount used, and the reaction proceeds whether the reaction system is in a completely dissolved state or in a suspended state. The reaction proceeds satisfactorily at room temperature without heating, but heating may be used to accelerate the reaction. Additionally, the reaction can be accelerated by adding an acid catalyst to the reaction system. Examples of acids include hydrochloric acid, sulfuric acid, and other hydrochloric acids, and acetic acid and other organic acids. The progress of the reaction can be monitored by thin layer chromatography and high performance liquid chromatography. After the reaction is complete, the desired product can be removed by filtering the precipitated crystals or, if no crystals are precipitated, by diluting with water and filtering the resulting precipitate. The compound of the present invention with even higher purity can then be obtained by recrystallization or column chromatography. The hydrazone compound of the present invention is used as a charge transporting material in combination with a charge generating material to constitute an electrophotographic photoreceptor. As the charge-generating substance, any substance that has charge-generating ability can be used, but inorganic materials such as selenium, selenium alloys, amorphous silicon, cadmium sulfide, phthalocyanine-based, perylene-based, perinone-based, indigo-based,
Examples include anthraquinone-based, cyanine-based, and azo-based organic dyes and pigments. In particular, azo compounds can be suitably used. Since the hydrazone compound of the present invention does not have film-forming ability by itself, it is used in combination with a binder to form a photosensitive layer. An insulating polymer is used as the binder, and examples thereof include polystyrene, polyacrylic acid, polyvinyl chloride, polyester resin, polycarbonate resin, epoxy resin, phenoxy resin, and boria ξ resin. can. In particular, polyester resins and polycarbonate resins can be suitably used. Poly N-vinylcarbazoles, which themselves have charge transport capabilities, can also be used as binders.

The structure of the photoreceptor is one in which a charge generating substance and a charge transport substance are contained in the same layer on a conductive support, as shown in Fig. 1, and one in which a charge generating substance and a charge transport substance are contained in the same layer on a conductive support, as shown in Fig. These include those in which a charge generation layer containing a charge generation substance is laminated on top of a charge generation layer containing a charge generation substance, and a charge transport layer containing a charge transport substance is laminated thereon, and those in which a charge generation layer and a charge transport layer are laminated in reverse.
Although any of the above-mentioned photoreceptors are effective in the present invention, the laminated photoreceptor shown in Section 2U; II is preferred because it provides excellent electrophotographic properties. The structure of the photoreceptor will be explained in more detail using the second example as an example. Examples of the conductive support include a metal plate made of aluminum, copper, zinc, etc., a plastic sheet or plastic film made of poly, ester, etc., on which a conductive material such as aluminum or SnOm is vapor-deposited, or paper treated with conductivity. Resin etc. are used. The charge generation layer can be formed by various methods such as vacuum deposition of a charge generation substance on a conductive support, coating and drying a solution of a charge generation substance, and coating and drying a fine particle dispersion of a charge generation substance. The charge generation layer can be shaped by selecting any method for the charge generation material. The thickness of the charge generation layer is preferably 0.01 to 5μ, more preferably 0.0μ.
It is 5 to 2μ. If the thickness is less than 0.01 μm, charge generation is not sufficient, and if it exceeds 5 μm, the residual potential is high and is not practical. The charge transport layer is formed by mixing and dissolving at least one hydrazone compound of the present invention and the binder in a suitable organic solvent, coating and drying. A charge transport substance other than the hydrazone compound of the present invention may be added to the charge transport layer and used in combination with the compound of the present invention. The charge transport layer contains a charge transport material in an amount of 10 to 95% by weight, preferably 30 to 90% by weight. If the content of the charge transport material is less than 10% by weight, almost no charge transport will occur, and if it exceeds 95% by weight, the mechanical strength of the photoreceptor will be poor and this is not practical. is 3 to 50μ, more preferably 5 to 30μ, and this thickness is 3μ
If it is less than 50μ, the amount of charge will be insufficient, and if it exceeds 50μ, the residual potential will be high, which is not practical. Further, an intermediate layer can be provided between the photosensitive layer and the conductive support, and suitable materials include boria oxide, nitrocellulose, casein, polyvinyl alcohol, etc., and the thickness of the layer is preferably 1 μm or less.

As described above, the electrophotographic photoreceptor of the present invention has the general formula (
In addition to the hydrazone compound (I), the photoreceptor may contain the conductive support, charge generating substance, binder, etc., and other structural elements of the photoreceptor function as structural elements of the photoreceptor. There are no particular restrictions as long as it is a thing. [Functions and Effects] The electrophotographic photoreceptor of the present invention has high sensitivity and excellent performance that does not deteriorate with repeated use by using the hydrazone compound represented by the general formula (I) as a charge transport material. have. [Examples] Hereinafter, the present invention will be specifically explained with reference to Examples, but the embodiments of the present invention are not limited thereto. Production Example 1 Disperse 28.7 g of a triphenylamine compound represented by the following formula in 200 d of N,N-dimethylformamide,
15.6 g of phosphorus oxychloride was added dropwise at 0 to 5°C.
After stirring at the same temperature for 1 hour, the temperature was raised to 70-75°C and stirred for 3 hours. After cooling to room temperature, the reaction solution was poured into 800 d of ice water, and aqueous sodium hydroxide solution was added to make it alkaline. After further stirring at room temperature for 1 hour, the precipitate was collected by filtration and dried. Recrystallization from aqueous ethanol gave 2.05 g of yellow crystals (sintered at 65°C) of an aldehyde compound represented by the following structural formula. 2.7 g of this aldehyde compound and 1.5 g of 1.1-diphenylhydrazine hydrochloride were mixed and dissolved in 5M N,N-dimethylformamide, and the mixture was stirred at room temperature for 3 hours. After confirming the disappearance of the raw material aldehyde compound, 50 ml of water was added, and the resulting precipitate was filtered and dried. The crude raw material was dissolved in a small amount of ethyl acetate, ethanol was added, and the resulting precipitate was filtered off and dried to obtain a yellow powder (sintered at 92°C). This compound was confirmed to be exemplified compound Nllll by elemental analysis. Elemental analysis value C HN Calculated value (X) 87.52 5.67 6.81
Actual value (χ) 87.68 5,54 6.77
Production Example 2 165 g of triphenylamine was added to 700 d of exemplified compound Na5 in dichloromethane.
After charging 91.4 g of zinc chloride, 155 g of diphenylacetyl chloride was added dropwise at room temperature while stirring.
After heating under reflux for 12 hours, it was left to stand. The reaction solution was poured into 1N ice water acidified with hydrochloric acid, the organic layer was separated using a separating funnel, and dichloromethane was distilled off. Purified by column chromatography (silica gel-benzene/hexane),
138 g of a compound represented by the following structural formula of pale yellow crystals (sintered from a melting point of 55°C) was obtained. 44 g of this compound was mixed with 20 g of N.N-dimethylformamide.
23 g of phosphorus oxychloride was added dropwise at 0°C. After keeping warm at 0°C for 2 hours, it was kept warm at 85°C for 4 hours. The reaction solution was poured into 3 liters of ice water and made alkaline with an aqueous solution of caustic soda. The precipitate was collected by filtration, dried, and purified by column chromatography (silica gel-benzene) to obtain 18 g of an aldehyde compound represented by the following structural formula as pale yellow crystals (melting point: 146.7-14B.3°C). 4.7 g of the above aldehyde compound and 2.4 g of 1,1-diphenylhydrazine hydrochloride were mixed with N,N-dimethylformamide 100-
(dissolved in water) and stirred at room temperature for 5 hours.
was added, and the resulting precipitate was separated by filtration, washed with water, and washed with methanol.
It was dry. Recrystallization from chloroform-ethanol gave 5.7 g of pale yellow crystals (melting point 191-192.5°C). This compound was confirmed to be Exemplified Compound 5 by elemental analysis. Elemental analysis value C H N Cl calculated value (χ) 87.89 5.22 6.45
5.45 Actual value (χ) 82.54 5.03
6.32 5.62 Production Example 3 A triphenylamine compound represented by the following formula (melting point 149-151.5
℃) was dispersed, and 6.4 g of phosphorus oxychloride was added dropwise at 0 to 5℃. After stirring at the same temperature for 1 hour,
The temperature was raised to ~75°C and incubated for 3 hours. After cooling the reaction solution to room temperature, it was poured into 40 ml of ice water, and an aqueous sodium hydroxide solution was added to make it alkaline. After further stirring for 1 hour, the precipitate was collected by filtration. The filtered mass was dissolved in 200 ml of benzene, After washing with dilute aqueous sodium hydroxide solution and water,
It was dried with anhydrous magnesium sulfate. After removing the desiccant, column chromatography (silica gel-benzene)
The effluent was concentrated to obtain 7.0 g of an aldehyde compound represented by the following structural formula in the form of a brown oil (solidified after standing; sintered at 93°C). The above aldehyde compound 5
．． 2g and 2.8g of 1,1-diphenylhydrazine hydrochloride
The synthesis was carried out in the same manner as in Production Example 2 using as a raw material, and 5.9 g of yellow crystals (melting point 163-165.5°C) were obtained. This compound was confirmed to be exemplified compound kl3 by elemental analysis. Elemental analysis value C HN Calculated value (X) 87.81 5.37 6.83
Actual value (X) 87.84 5.31 6.71
Example 1 Polyester resin (manufactured by Toyobo, trade name: Byron 200)
J) 0.5g, and 0.5g of tetrakisazo dye (CG-1) represented by the following structural formula. ) and 50 g of tetrahydrofuran were pulverized and mixed in a ball ξ mill, the resulting dispersion was applied to an aluminum plate using a wire bar, and dried at 80° C. for 20 minutes to form a charge generation layer of about 0.5 μm. ．． Exemplary compound Nnl. 1 g, polycarbonate resin (product name "Panrai" K-1300J
A solution of Ig (manufactured by Teijin Chemical Co., Ltd.) dissolved in 10 g of chloroform was applied using a wire bar, and dried at 80"C for 30 minutes to form a charge transport layer with a thickness of about 18 μm, as shown in Figure 2. A laminated photoreceptor was fabricated. An electrostatic copying paper tester (■Model EP manufactured by Kawanichi Denki Seisakusho)
-8100), the photoreceptor was charged by corona discharge with an applied voltage of -6κV, the surface potential v0 at that time was measured, the photoreceptor was left in a dark place for 2 seconds, the surface potential V, at that time was measured, and then the photoreceptor With the surface illuminance at 51 u×, we irradiated it with light from a halogen lamp (color temperature 2856°κ) and measured the time for the surface potential to reach A of V, and the half M exposure amount E
′A(lux −sec) was calculated. Also, the surface potential v1 after 10 seconds of light irradiation! That is, the residual potential was measured.
Furthermore, the charging exposure operation was repeated 1000 times. Examples 2 to 25 The tetrakisazo dye (CG-
1) and the following structural formula 9. ). ) r1 (CC 4). ) (CG 5). ) Disazo dyes (CG-2), (cc-3),
(CG-4), (cc-5) and τ-phthalocyanine (
A photoreceptor was prepared in the same manner as in Example 1 using CG-6) in combination with the shidrazone compound of the present invention, and the same measurements were carried out. The charge generating material used, the charge transporting material, and the measurement results are shown in Table 2 together with Example 1. Comparative Example 1 The disazo dye (CG-3) was used as a charge generating substance, and 2.5-bis(4-diethylanξnophenyl)-1.3.4-oxadiazole (CT-1) was used as a charge transporting substance.
) A photoreceptor was produced in the same manner as in Example 1, except that
Similar measurements were made. The measurement results are shown in Table 2. Example 26 The photoreceptor produced in Example 1 was attached to a commercially available electrophotographic copying machine to make copies, and even on the 10,000th copy, clear images with no fogging that were faithful to the original images were obtained. As described above, it can be said that the electrophotographic photoreceptor using the hydrazone compound of the present invention has high sensitivity, stable performance even after repeated use, and excellent durability. The photoreceptor of the present invention can be used not only in electrophotographic copying machines, but also in various printers, electrophotographic engraving systems, etc. that apply electrophotographic copying principles.

[Brief explanation of drawings]

Figures 1 and 2 are cross-sectional views showing examples of the structure of electrophotographic photoreceptors. The respective symbols in Figures 1 and 2 are as follows.

Claims (1)

[Claims] 1) The photosensitive layer on the conductive support has the general formula (I) ▲mathematical formula, chemical formula, table, etc.▼(I) (in the formula, R_1 and R_2 are optionally substituted aryl groups) , R_1 and R_2 may be bonded directly or through a linking group, R_3 is a hydrogen atom, a halogen atom, an alkyl group, or an optionally substituted phenyl group, and R_4 and R_5 are an alkyl group, an aralkyl group. or an optionally substituted aryl group, at least one of which is an optionally substituted aryl group.