JPS63206758A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To increase the sensitivity and durability of a sensitive body by incorporating a specified hydrazone compd. as an electric charge transferring substance into the photosensitive layer. CONSTITUTION:An electric charge generating layer 6 contg. an electric charge generating substance 2 and an electric charge transferring layer 5 contg. a hydrazone compd. represented by formula I as an electric charge transferring substance 3 are successively laminated on an electrically conductive supporting body 1. The layer 5 is formed by dissolving the substance 3 and a binder such as polyester in an org. solvent such as chloroform and by applying the resulting soln. to the surface of the layer 6. The layers 6, 5 may be laminated in the reverse order and a single layer type photosensitive layer contg. the dispersed substances 2, 3 may be formed in place of the layers 5, 6. In the formula I, each of R1 and R2 is (substd.)alkyl, aralkyl or aryl but at least one of them is (substd.)aryl.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a photoreceptor for electrophotography. More specifically, the present invention 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 have low sensitivity. For example, photoreceptors using selenium-based materials have excellent sensitivity, but they do not fully satisfy the performance requirements of electrophotographic photoreceptors such as photostability, moisture resistance, and durability. Otherwise, the characteristics of the photoreceptor tend to deteriorate due to crystallization due to the adhesion of dirt, etc. Also, since it is manufactured by vacuum evaporation, it is expensive (and it is difficult to process into a belt shape because it is not flexible). Photoreceptors using cadmium sulfide-based materials have problems in moisture resistance and durability, and photoreceptors using zinc oxide have problems in durability.

In order to overcome the drawbacks of photoreceptors using these Ma-based photosensitive materials, various studies have been made on photoreceptors using photosensitive materials.

In recent years, among photoreceptors developed to improve the above-mentioned drawbacks, a functionally separated photoreceptor in which charge generation function and charge transport function are shared by separate substances has been attracting attention. In this functionally separated type photoreceptor, materials having respective functions can be selected from a wide range of materials and combined, so that it is possible to produce a highly sensitive and highly durable photoreceptor.

Electrophotographic properties required for charge transport materials include (I)
The ability of the receiver to accept the charge generated by the charge-generating material is sufficiently high; (2) the receiver must transport the introduced charge quickly; and (3) the charge must be sufficiently transported even in low electric fields and the charge may remain. In addition, as a photoreceptor, it is stable against charging, exposure, and phenomena during copying, and against light and heat received during the repeated transfer process, and produces reproduced images that are faithful to the original. Durability is required.

Various compounds have been proposed as charge transport materials.For example, poly-N-vinylcarbazole has been known as a photoconductive material for a long time, and products using this as a charge transport material have been put into practical use. However, it itself lacks flexibility, is brittle, and is prone to cracking, resulting in 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 any desired composition to form a photosensitive layer. Many charge transport substances have been proposed as low molecular weight compounds. For example, hydrazone compounds have high sensitivity as charge transport substances, and are disclosed in Japanese Patent Application Laid-Open No. 55-4676.
No. 1, JP-A-55-52064, JP-A-57-581
No. 56, JP-A No. 58-58157, 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. The resulting image had reduced contrast or had a lot of fog.

Although many other charge transport materials have been proposed, the current situation is that none of them practically satisfies the required performance as an electrophotographic photoreceptor, and the development of an even better photoreceptor has been desired.

[Problem that the invention seeks to solve]

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.

[Means to solve the problem]

The present inventors have made extensive studies to solve the above problems, and
As a result, the general formula (I,) (wherein R5 and Ro are an alkyl group, an aralkyl group, or an aryl group that may have a substituent, and at least one of them is an aryl group that may be substituted) show,)
The present inventors have discovered that a novel hydrazone compound represented by the formula can provide an electrophotographic photoreceptor having excellent properties such as high sensitivity and high durability, and have thus arrived at the present invention.

That is, the present invention provides a photosensitive layer on a conductive support having the general formula (I) (wherein R1 and R2 are an alkyl group, an aralkyl group, or an aryl group which may have a substituent, and at least one of them is indicates an optionally substituted aryl group)
This is an electrophotographic photoreceptor characterized by containing a hydrazone compound represented by:

Examples of the alkyl group in R and R in the general formula (I) include a methyl group, an ethyl group, a linear or branched propyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, etc. Examples of the aralkyl group include a benzyl group, a phenethyl group, a cinnamyl group, and a naphthylmethyl group. Examples of aryl groups include phenyl, naphthyl, anthryl, etc. Substituents for aryl include alkyl groups such as methyl and ethyl groups, alkoxy groups such as methoxy and ethoxy groups, and chlorine atoms. , a halogen atom such as a bromine atom, and a dialkylamino group such as a dimethylamino group or a diethylamino 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 to these.

The hydrazone compound represented by the general formula (T) can be synthesized by a conventional method.
F R1 (II) (In the formula, R1 and R2 are the same as in general formula (J).)
A hydrazine compound represented by or a mineral acid salt thereof in a suitable solvent (for example, methanol, ethanol, 1.
It can be easily obtained by reacting with (4-dioxane, tetrahydrofuran, N,N-dimethylformamide, acetic acid).

The hydrazone compound of the present invention is used as a charge transporting material in combination with a charge generating material to form 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, azo-based dyes and pigments.

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, but
Examples include polystyrene, polyacrylamide, polyvinyl chloride, polyester resin, polycarbonate resin, epoxy resin, phenoxy resin, and polyamide resin.

In particular, polyester resins and polycarbonate resins can be suitably used. Poly-N-vinylcarbazole, which itself has charge transport capabilities, can also be used as a binder.

As shown in Figure 1, the photoreceptor has a structure in which a charge generating substance and a charge transporting substance are contained in the same layer on a conductive support, and as shown in Figure 2, a charge generating substance and a charge transport substance are contained in the same layer on a conductive support. There are those in which a charge generation layer containing a charge generation substance is formed 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 photoreceptors having the above configurations are effective in the present invention, the laminated type photoreceptor shown in FIG. 2 is preferred since it provides excellent electrophotographic properties.

The structure of the photoreceptor will be explained in more detail using the second rgJ as an example.

As the conductive support, a metal plate made of aluminum, copper, zinc, etc., a plastic sheet or plastic film made of polyester, etc., on which a conductive material such as aluminum, SnO□, etc. is vapor-deposited, or conductively treated paper, 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 formed by selecting a charge generation material by any method. 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 will not be sufficient, and if it exceeds 5 μm, the residual potential will be high and it is not practical.

The charge transport layer is formed by mixing and dissolving the hydrazone compound of the present invention and the binder in an appropriate organic solvent, coating and drying. The charge transport layer contains 10 to 95% by weight of a charge transport substance,
It is preferably contained in an amount of 30 to 90% by weight. If the amount of the charge transport material is less than 10% by weight, charge transport will hardly occur, and if it exceeds 95% by weight, the mechanical strength of the photoreceptor will be poor, which is not preferred in practice.

The thickness of the charge transport layer is preferably 3 to 50μ, more preferably 5 to 30μ, and this thickness is 3g.
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 preferred in practice.

Further, an intermediate layer can be provided between the photosensitive layer and the conductive support, and the material thereof is suitably polyamide, nitrocellulose, casein, polyvinyl alcohol, etc., and the film thickness is preferably 1 μm or less.

As described above, the electrophotographic photoreceptor of the present invention has the formula -i (
In addition to the hydrazone compound of I), the photoreceptor contains the conductive support, charge generating substance, binder, etc., but the other components of the photoreceptor may function as components of the photoreceptor. It is not particularly limited.

[Action and effect]

The electrophotographic photoreceptor of the present invention has high sensitivity by using a hydrazone compound represented by the general formula (I) as a charge transport material, and has excellent performance that does not deteriorate with repeated use.

(Margins below) [Examples] The present invention will be specifically described below with reference to Examples, but the embodiments of the present invention are not limited thereto.

Production Example Synthesis of Exemplified Compound-1 4. 3 g of 4'-diformyltriphenylamine and N
-Methyl-N-phenylhydrazine 2.7g N,N-
Mix and dissolve in 1001 dl of dimethylformamide, IN
- 2 td of hydrochloric acid was added and stirred at room temperature for 8 hours. water 100
-, the resulting precipitate was collected by filtration, dried, and recrystallized from ethyl acetate and a small amount of ethanol.
4-195℃, λwax (COCl2) 393m5+
) 2.5g was obtained. This product was confirmed to be Exemplified Compound-1 by elemental analysis.

Actual value CB3.01 B 5.97 N 1
1.09 Example 1 Polyester resin (manufactured by Toyobo, trade name "Byron 200")
J) 0.5g, 0.5g of a disazo dye represented by the following structural formula, and 50g of tetrahydrofuran were ground and mixed in a ball mill, the resulting dispersion was applied to an aluminum plate using a wire bar, and dried at 80°C for 20 minutes. A charge generation layer having a thickness of about 0.5 μm was formed.

A solution prepared by dissolving 11 g of the exemplified compound and 1 g of polyester resin (trade name "Vylon 200" manufactured by Toyobo Co., Ltd.) in 10 g of chloroform was applied onto this charge generation layer using a wire bar, and dried at 80°C for 30 minutes to a thickness of approx. A charge transport layer having a thickness of 18 μm was formed to produce a laminated photoreceptor shown in FIG. 2.

Electrostatic copying paper testing device (Model EP manufactured by El River Electric Manufacturing Co., Ltd.)
A-8100) was used to charge the photoreceptor by corona discharge at an applied voltage of -6 KV, and the surface potential V at that time.

Measure the surface potential v2 after leaving it in the dark for 2 seconds.
Then, with the surface illuminance of the photoconductor at 51ux, light from a halogen lamp (color temperature 2856°K) is irradiated to measure the time for the surface potential to reach v2 of 2, and the half-reduction exposure amount E' A (lux-sec) was calculated. Furthermore, the surface potential V+Z, that is, the residual potential, was measured after 10 seconds of light irradiation. Furthermore, the charging exposure operation was repeated 1000 times.

Example 2 A photoreceptor was prepared in the same manner as in Example 1, except that a disazo dye represented by the following structural formula was used as a charge generating substance, and the same measurements were carried out.

Example 3 A photoreceptor was prepared in the same manner as in Example 1, except that a disazo dye Cσ represented by the following structural formula was used as a charge generating substance, and the same measurements were carried out.

Comparative Example-1 A disazo dye represented by the following structural formula was used as a charge generating substance, and 2.
5-bis(4-diethylaminophenyl)-1,3,4
A photoreceptor was prepared in the same manner as in Example 1 except that -oxadiazole was used, and the charging and exposure operation was repeated 1000 times.

The measurement results of Examples 1 to 3 and Comparative Example 1 are shown in Table 2.

Example 4 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 without fogging that were faithful to the original images were obtained.

(The following is a blank space) Table 2 As shown above, the electrophotographic photoreceptor using the hydrazone compound of the present invention has high sensitivity and stable performance even after repeated use, and is also excellent in durability. I can say that.

[Brief explanation of the drawing]

FIGS. 1 and 2 are cross-sectional views showing an example of the structure of an electrophotographic window light body. In FIGS. 1 and 2, the respective symbols are as follows. 1-111 conductive support 4.4'-m-photosensitive layer 2-
---Charge generating substance 5--Charge transport layer 3-
--- Charge transport material 6 --- Charge generation layer Patent applicant Mitsui Toatsu Chemical Co., Ltd. Figure 1 Figure 2

Claims (1)

[Claims] 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 alkyl, aralkyl or an aryl group, at least one of which is an optionally substituted aryl group).