JPS6123154A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To obtain an electrophotgraphic sensitive body high in solubility in a polymer binder and high in sensitivity and small in fatigue by forming a layer contg. a specified hydrazone compd. as an electrostatic charge transfer material. CONSTITUTION:A photosensitive layer 5 composed of a charge generating layer 3 composed essentially of a charge generating material 2, and a charge transfer layer 4 uniformly contg. a hydrazone compd. is formed on a conductive substrate 1. The hydrazone compd. is represented by formula I and prepared by reaching 2-methyl-4-dibenzylaminobenzaldehyde represented by formula II with 1,1-diphenylhydrazine or its mineral acid salt in a solvent, such as methanol or ethanol, at the reflux temp. of solvent, or lower. When needed, the small amt. of a tertiary amine, such a pyridine or triethylamine, an inorg. acid, or an org. acid, such as acetic acid, is used as a condensing agent, and the hydrazone compd. is used in the amt. of 10-90wt%, preferably, 30-90wt%.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to an electrophotographic photoreceptor, and more particularly, to an electrophotographic photoreceptor comprising a charge generation layer and a charge transport layer provided on a conductive support. , relates to an electrophotographic photoreceptor having a layer containing 2-methyl-4-dibenzylaminohensaldehyde)"-1,1-diphenylhydrazone represented by the following formula CI) as a charge transport layer. .

[Conventional technology]

In recent years, inorganic photoconductive substances that have been widely used as electrophotographic photoreceptor materials include selenium, cadmium sulfide, zinc oxide, etc., and organic photoconductive substances such as po+)N. -Various photoconductive polymers including vinylcarbazole and polyvinylanthracene, and low-molecular photoconductive substances such as A]K have been proposed.

Among them, photoconductive polymers such as P+)N-carbazole do not have sufficient film-forming properties and continuity, and have the disadvantage of cracking or peeling when left in the form of a film. occurs. Therefore, plasticizers, binders, etc. are added to compensate for these drawbacks, but while this improves flexibility, it also has the drawback of reducing electrophotographic properties such as sensitivity and residual potential. However, it was extremely difficult to obtain a practical photoreceptor. On the other hand, low-molecular organic photoconductive compounds do not have film-forming ability by themselves, but they can be used to form films by appropriately selecting a polymeric binder such as polyester resin, polyvinyl chloride resin, or polycarbonate resin. It is possible to obtain a photoreceptor with excellent film formability and flexibility.

However, in recent years, as seen in U.S. Pat. No. 3,791,826, methods have been developed in which the two functions of a photoconductive material, namely the generation of charge carriers and the transfer of the generated charges, are performed by separate organic compounds. It is widely proposed. Charge transport materials are often low-molecular organic photoconductive compounds, and are selected from a wide range of materials to meet the characteristics required for photoreceptors, i.e., high surface charge, high charge retention ability, and high photosensitivity. It has also become possible to select compounds with functions such as almost no residual potential. A large number of compounds have been introduced as charge transport materials, and one example is a hydrazone-based compound disclosed in Japanese Patent Application Laid-Open No. 54-59143. However, none of these known compounds has yet been found to have sufficiently satisfactory electrophotographic properties.

[Problem that the invention seeks to solve]

In other words, many of these known charge transport materials have problems with solubility in polymeric binders, and those with low solubility are difficult to obtain a uniform film, and even when dissolved, it is difficult to obtain a uniform film. If there is a phenomenon in which crystals precipitate over time, the performance of electrophotography is significantly reduced.

However, when a conventional electrophotographic photoreceptor having a functionally separated type photosensitive layer is used repeatedly according to an electrophotographic process, the ability to recover the original charging characteristics decreases, shortening the life of the photoreceptor. have. That is,
When the actual electrophotographic process of charging, dark decay, light decay, and cleaning is repeated many times, one of the following occurs: surface charge fluctuation after charging, decrease in charge retention ability, decrease in photosensitivity, increase in residual potential, etc. Alternatively, two or more optical fatigue phenomena may occur, significantly deteriorating the performance of electrophotography, which is a major problem in practical use.

Therefore, an object of the present invention is to provide an electrophotographic photosensitive material that has excellent solubility in a polymeric binder, high sensitivity, low residual potential, low optical fatigue even when used repeatedly according to an electrophotographic process, and excellent durability. Dedicated to donating your body.

[Means for Solving the Problems] ``In order to achieve the above object, the present inventors conducted intensive research on organic photoconductive materials and found that a specific hydrazone compound satisfies various requirements for electrophotography. They discovered this and completed the present invention.

That is, the present invention uses a hydrazone compound represented by the following formula (1) as a charge transporting material, which has high solubility in a polymeric binder and is capable of producing an electrophotographic photoreceptor with high sensitivity and low optical fatigue. An object of the present invention is to provide an electrophotographic photoreceptor having a layer containing it.

The hydrazone compound [I] used in the present invention has the following formula [
11) 2-methyl-4-dibenzylaminobenzaldehyde and 1,1-diphenylhydrazine or its mineral acid salt in a solvent such as methanol or ethanol,
It can be produced by reacting at the reflux temperature of the solvent or a temperature lower than that. In this reaction, a small amount of a tertiary amine such as pyridine or triethylamine, or an inorganic acid or an organic acid such as acetic acid may be used as a condensing agent, if necessary.

Next, a basic method for manufacturing the electrophotographic photoreceptor of the present invention will be described, but the present invention is not, of course, limited to this example.

An electrophotographic photoreceptor having a layer containing the hydrazone compound of the present invention can be manufactured in the shape shown in FIG. That is, a photosensitive layer (5) consisting of a charge generation layer (3) mainly containing a charge generation substance (2) and a charge transport layer (4) uniformly containing a hydrazone compound is formed on a conductive support (1). will be established. Here, the hydrazone compound is used as a charge transport material and forms a charge transport layer together with the binder.

'The light transmitted through the Lu charge transport layer reaches the charge generation substance dispersed in the charge generation layer and generates charges.

The charge transport layer receives this charge injection and transports it. In order to efficiently generate charge carriers in the charge generating substance and the hydrazone compound charge generating substance, it is necessary to transmit light to the surface of the charge generating substance. The hydrazone compound of the present invention exhibits almost no absorption in the visible region, and is characterized in that it functions particularly effectively as a charge transport material when combined with a charge generating material that generally absorbs light in the visible region and generates charges.

To prepare the photoreceptor shown in Figure 1, a charge-generating substance is vacuum-deposited onto a conductive support, or fine particles of a charge-generating substance are placed in a suitable bath medium in which a binder is dissolved as necessary. The dispersion obtained by dispersion is applied and dried, and if necessary, the surface is finished by a method such as puff polishing to adjust the film thickness, and then a hydrazone compound and a binder'f are applied thereon. : Obtained by applying and drying a solution of Application is carried out using conventional means, such as a doctor blade, wire bar, etc.

The thickness of the charge generation layer is 5μ or less, preferably 2μ or less, and the charge transport layer has a thickness of 3 to 50μ, preferably 5 to 5μ.
It is 20μ. The proportion of the hydrazone compound in the charge transport layer is 10 to 90 parts, preferably 30 to 90 parts.

As the conductive support, a metal plate or foil made of aluminum or the like, a plastic film on which a metal such as aluminum is vapor-deposited, or paper treated with conductivity is used. As the binder, polyester resin, polyvinyl chloride resin, acrylic resin, methacrylic resin, polystyrene resin, polycarbonate resin, etc. are used, and among them, polyester resin and polycarbonate resin are preferred.

Examples of charge-generating substances include inorganic materials such as selenium and cadmium sulfide, and examples of organic materials include CI Pigment Blue 25 (color index Cl21180).
), CI Pigment Red 41 (CI21200), C
I Acid Red 52 (CI45100), CI
Azo pigments such as Basic Red (CI 45210), CI Pigment Blue 16 (CI74100)
) and other phthalocyanine pigments, CI Bat Brown 5
(CI73410), CI Bat Die (CI73)
Indigo pigments such as 030'), Argo Scarlet R (Beyer t[), Indance Scarlet R]
Perylene pigments such as (manufactured by Bayer), as well as chlorodiane blue, i.e., 4,4'-((3,3'
-dichloro-4,4/-biphenylylene)bis(azo)
]-]bis]3-hydroxy-2-naphthalinidomethyl squalium, i.e. 2,4-bis-(2-methyl-
4-dimethylaminophenyl)-1,3-cyclobutadienediylium-1,3-diolate, hydroxysquarium, 2,4-bis-(2-hydroxy-
Organic pigments such as 4-dimethylaminophenyl)-1°3-cyclobutadienediilium-1,3-diolate are used.

〔Example〕

Next, the present invention will be explained with reference to synthesis examples, examples, and comparative examples.

Synthesis Example I N,N~Dibenzyl-m-)luidine Synthesis m-Toluidine 10.7 g-1 Sodium acetate 16.42, Iodine 0.2? A mixture of 107 g of toluene was heated to 95°C, and 25.3 P of benzyl chloride was added dropwise thereto over 1 hour. After reacting at 100°C for 7 hours, cool and add toluene 10
．． Add 7g-520φ caustic soda aqueous solution 409-
Separate the liquid, wash with water, concentrate, recrystallize from methanol, and
N-dibenzyl-m-toluidi 722.6 fI- was obtained. m975-6°C, theoretical yield 78.7%.

Synthesis of 2-Methyl-4-benzylaminobenzaldehyde 14.67 ml of dimethylformamide and 75 rfLl of 1,2-dichloroethane were added dropwise with 30.67 ml of phosphorus oxychloride at 5 to 10'C under stirring and cooling over 40 minutes. After stirring at room temperature for 1 hour, a solution of 50 grams of N,N-dibenzyl-m-)shiidine obtained above in 200 ml of 1,2-dichloroethane was added dropwise at 5 to 10° C. over 2.5 hours. After stirring at room temperature for 1 hour, the mixture was further stirred under reflux for 4 hours. - After standing overnight, the mixture was poured into a solution of 1002 sodium acetate and 500 ml of water, stirred at 70'C for 2 hours, extracted with dichloroethane, washed with water and concentrated to obtain crude crystals of 55z. Recrystallization from methanol gave 2-methyl-4-benzylaminobenzaldehyde 47ii1-. mp84-85℃,
Theoretical yield: 85.8 cm.

2-Methyl-4-dibenzylaminobenzaldehyde
4.77 g of 2-methyl-4-benzylaminobenzaldehyde obtained in the synthesis of 1,1-diphenylhydrazone, 3.3 g of 1,1-diphenylhydrazine hydrochloride, 20 M ethanol, and 1.6 t of pyridine were stirred under reflux for 5 hours. . After cooling, the formed crystals 7.7f'<fI5 were collected and recrystallized from ethyl acetate to give 2-methyl-4-dibenzylaminobenzaldehyde-1,1-diphenylhydrazone6.
Obtained 9 g.

mp 148°C, theoretical yield 94%.

Example 1 Chlordiane Blue 0.2! 2-, polycarbonate resin (Mitsubishi Gas Chemical Co., Ltd. “Nipilon S-2
000J) is mixed with a dichloroethane solution 4z containing 5g, 20g of dichloroethane is added, and the mixture is ground to 1μ or less using a vibrating mill to create a dispersion of the charge carrier generating pigment, which is then mixed into a polyester film on which aluminum is vapor-deposited. A charge carrier generation layer was applied on top using a wire bar and dried at 45° C. to a thickness of about 1 μm. on the other hand,
0 of 2-methyl-4-dibenzylaminobenzaldehyde-1,1-diphenylhydrazone prepared in Synthesis Example 1
．． A charge transport layer forming liquid was prepared by dissolving 1y- in a dichloroethane solution 29- containing 5 parts of the above polycarbonate resin. This was applied onto the charge carrier generation layer using a doctor blade so that the dry film thickness was 15 μm, and dried at 45° C. to prepare a photoreceptor. The static photographic properties of this photoreceptor were measured using an electrostatic copying paper tester model rSP-428 (manufactured by Kawaguchi Denki Seisakusho). That is, the photoreceptor was heated to -6KV.
A corona discharge of 5 seconds is performed to charge the surface, and the surface potential is V.

(unit, volt), hold it in a dark place for 5 seconds, and then irradiate it with light with an illuminance of 5 lux using a tungsten lamp, and the amount of exposure necessary to attenuate the surface potential by 1/2 and 1/6. , that is, half-reduced exposure iE1/2 (lux/second) and E115 (lux/second), surface residual potential vR (volt) after irradiation with light with an illuminance of 5 lux for 20 seconds.
As a result, Vo is 1620 volts, E1/2 is 5.5 lux seconds, and El/6 is 14.0 lux seconds.
The %VR in seconds was 0 volts.

Example 2 The photoconductor obtained in Example 1 was further heated to 10,000 lux.
The residual potential was removed by irradiating it with light for 3 seconds, and this material was charged again by performing -6KV corona discharge for 5 seconds.
Each characteristic value was determined again. Table 1 shows the results of repeating this cycle.

Table 1 Comparative Example 1 Example 1. 2-methyl-4-dibenzylaminobenzaldehyde-1,1-diphenylhydrazone 0.1y- of the compound of the present invention in JP-A-54-591
Known hydrazone compounds disclosed in Publication No. 43,
That is, 4-diethylaminobenzaldehyde-1,1-diphenylhydrazone 0.
A photoreceptor was produced in the same manner as in Example 1 except that 1 fF was used.

The electrophotographic X characteristics of this photoreceptor were measured in the same manner as in Examples 1 and 2, and the results are shown in Table 2.

From Table 2 onwards, comparing the results of Examples 1 and 2 and Comparative Example,
The electrophotographic photoreceptor of the present invention has almost the same characteristic values at the first time, but when repeated, there is little variation in surface charge, photosensitivity, residual potential, etc., and it clearly has excellent durability. I understand.

〔Effect of the invention〕

The photoreceptor of the present invention obtained as described above has excellent features such as extremely high sensitivity, high flexibility, no change in characteristics due to charging exposure, and high durability.

[Brief explanation of the drawing]

FIG. 1 shows a sectional view of one example of the electrophotographic photoreceptor of the present invention. 1... Conductive support 2... Charge generating substance 3...
・Charge generation layer 4...Charge transport layer 5 containing 2-methyl-4-dibenzylaminobenzaldehyde-1,1-diphenylhydrazone...Photosensitive layer or higher

Claims (1)

[Claims] 1. In an electrophotographic photoreceptor in which a charge generation layer and a charge transport layer are provided on a conductive support, the charge transport layer has the following formula [I] ▲ Numerical formula, chemical formula, table, etc. An electrophotographic photoreceptor comprising a layer containing 2-methyl-4-dibenzylaminobenzaldehyde-1,1-diphenylhydrazone represented by ▼ [I].