JPH0524506B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to an electrophotographic photoreceptor, and more specifically, the present invention relates to an electrophotographic photoreceptor, and more specifically, a specific enamine compound is contained as a charge carrier transfer agent in a photoconductive photosensitive layer formed on a conductive substrate. This invention relates to an electrophotographic photoreceptor. (Prior Art) Conventionally, photoconductive materials for photoreceptors used in electrophotography include inorganic materials such as selenium, cadmium sulfide, and zinc oxide. The "electrophotographic method" referred to here is a general method in which the electrostatic charge is charged positively or negatively by corona discharge in a dark place, and then the charge in the exposed area is selectively erased by image exposure. Obtain a latent image, and in this latent image area,
By attaching positively or negatively charged colored particles,
This is an image forming method that develops and visualizes images. The characteristics required of a photoreceptor used in such an electrophotographic method are (1) to be able to be charged to a sufficient potential in a dark place, (2) to be able to maintain the charged potential for a sufficient time in a dark place, ( 3) It is required that the charge disappears quickly after being irradiated with light. In recent years, in order to compensate for these drawbacks, organic electrophotographic photoreceptors using various organic substances have been proposed. Organic electrophotographic photoreceptors are () lightweight, () easy to process, and can be processed into films, sheets, and drums; ()
It has the following characteristics: it is easy to design spectral sensitivity and sensitivity by selecting and combining materials, () non-toxic materials can be used, and users can handle and dispose of it themselves. Many of them are already in practical use. For example, poly-N-vinylcarbazole and 2,
4,7-trinitrofluoren-9-one (Japanese Patent Publication No. 50-10496), a photoreceptor made of poly-N-vinylcarbazole sensitized with pyrylium salt (US Patent No. 3141770), thiapyrylium Photoreceptors made of eutectic complexes of salt and triphenylmethane (Japanese Unexamined Patent Publication No. 47-10735) are known, and recently, charge generation and charge transfer are separated into separate functions, and multilayer structures have been developed. The development of organic photoreceptors is being actively carried out. The advantage of the functionally separated type is that the performance of the photoreceptor can be varied by selecting the charge generation layer and the charge transfer layer separately. for example,
High sensitivity and panchromaticity can be achieved by selecting the charge generation layer, and durability and flexibility can be achieved by selecting the charge transfer layer. Based on this idea, as something that has already entered the practical stage,
One in which dimethylperylimide is used as a charge generation layer and oxadiazole is used as a charge transfer layer [J.Appl.
Photo・Eng.・4 118 (1978)], a charge generation layer made of squarylium, chlorodiane blue, etc., and a pyrazoline charge transfer layer (Japanese Unexamined Patent Application Publication No. 1983-1993)
105536, JP-A-49-105537), etc. are known. All of them have excellent characteristics as photoreceptors for electrophotography, but the electrophotographic method has not only been applied to copying machines but also to various types of printers such as laser printers, LED printers, and liquid crystal printers. As the applications of photoreceptors become more diverse, such as colorization, the characteristics required of photoreceptors are also changing subtly. For this reason, many charge generation agents and charge transfer agents are currently being developed. (Problems to be Solved by the Invention) Although the above-mentioned inorganic substances have many characteristics that suit the various required characteristics described above, it is also true that they also have various drawbacks. be. For example, selenium, which is currently widely used, is difficult to produce, is expensive, is not flexible, is difficult to process into a belt, and its properties deteriorate due to heat and humidity. Therefore, sufficient care must be taken when handling it. The major disadvantage of selenium is its toxicity.
When handling photoreceptors, it is necessary to be careful about their toxicity. For this reason, general users are unable to dispose of used photoconductors, incinerate them, or otherwise dispose of them, which is a major obstacle to the widespread use of copiers and printers that utilize electrophotography. . In addition to selenium, cadmium sulfide and zinc oxide can also be dispersed in a binder as an inorganic substance and used as a photoreceptor. However, these materials have many drawbacks in mechanical properties such as hardness, friction resistance, and tensile strength, and they must be used with properties that remain unsolved or have many problems for long-term repeated use. (Means for Solving the Problems) The present invention aims to obtain a highly sensitive and highly durable charge transfer layer, and only a specific enamine compound described below has excellent sensitivity and resistance. In addition, the inventors discovered that they have excellent storage stability and stability against light irradiation, leading to the completion of the present invention. Many enamine compounds are known, and many pioneering examples of functionally separated photoreceptors with charge transfer layers have been proposed, but there are only a few examples of enamine compounds that have been put to practical use. For example, Journal of Imaging
Science Vol 29, No. 1, P7, Jan./Feb. (1985)
In the case of , the typical enamine compound is N-[2,2-Bis(4-Methoxyphenyl)
ethenyl]-4-Methoxy-N-(4-
Methoxyphenyl)-Benzenamine N-[2,2-Bis(4-Ethoxyphenyl)
ethenyl]-4-Methoxy-N-(4-
An example using a charge transfer layer such as methoxyphenyl)-benzenamine is described. However, the general formula () such as the compound of the present invention
There are no examples disclosed in which an enamine structure in which R ₂ shown in the formula is substituted with an alkyl group such as a methyl group by a phenyl ring is disclosed. Furthermore, it is pointed out that the enamine compound charge transport layer in the report requires further improvement in terms of sensitivity, repeated use characteristics, and light resistance. In view of the above circumstances, the present inventors have carried out intensive research and have found that by using a specified enamine compound represented by the following general formula () in the charge transfer layer, the enamine compound known up to now can be It has been found that a photoreceptor which is significantly improved compared to the above method can be obtained. (However, R ₁ is a methyl group or ethyl group, R ₂
represents a methyl group substituted at the para- or meta-position, or a hydrogen atom. ) The specified enamine compound used in the present invention is _2,2- (4,4'-
an aldehyde compound such as dimethoxyphenyl)acetaldehyde or 2,2-(4,4'-diethoxyphenyl)acetaldehyde and p,p'-ditolylamine or m,m'-ditolylamine,
It can be obtained by dehydrating an aromatic amine such as diphenylamine in a reaction solvent such as benzene or toluene in the presence of p-toluenesulfonic acid by a known method. That is, it is the following enamine compound. N-[2,2-Bis(4-Methoxyphenyl)
ethenyl]-4-Methyl-N-(4-
Methylphenyl)-Benzenamine N-[2,2-Bis(4-Methoxyphenyl)
ethenyl]-3-Methyl-N-(3-
Methylphenyl)-Benzenamine N-[2,2-Bis(4-Methoxyphenyl)
ethenyl]-N-Phenyl-Benzenamine N-[2,2-Bis(4-Ethoxyphenyl)
ethenyl]-4-Methyl-N-(4-
Methylphenyl)-Benzenamine N-[2,2-Bis(4-Ethoxyphenyl)
ethenyl]-3-Methyl-N-(3-
Methylphenyl)-Benzenamine N-[2,2-Bis(4-Ethoxyphenyl)
ethenyl]-N-phenyl-Benzenamine Furthermore, in the enamine compound that can be expected from the general formula (), a propyl group or a butyl group in which R ₁ has 3 or more carbon atoms can be introduced. On the other hand, R ₂ has
Although a methyl group is used in the present invention, an enamine structure in which an ethyl group, propyl group, or butyl group is introduced at the Para position or metha position is also expected. For example, N-[2,2-Bis(4-Methoxyphenyl)
ethenyl]-4-Propyl-N-(4-
Propylphenyl)-Benzenamine N-[2,2-Bis(4-Ethoxyphenyl)
ethenyl]-3-Proprl-N-(3-
Propylphenyl)-Benzenamine N-[2,2-Bis(4-Methoxyphenyl)
ethenyl〕-4-Butyl-N-(4-Butylphenyl)
-Benzenamine N- [2,2-Bis(4-Ethoxyphenyl)
ethenyl〕-3-Butyl-N-(3-Butylphenyl)
-Benzenamine N- [2,2-Bis(4-Propoxyphenyl)
ethenyl]-4-Propyl-N-(4-
Propylphenyl)-benzenamine, etc. As mentioned above, the enamine compound used in the present invention is
Uses conventionally used for charge transfer agents, such as photoreceptors in which sensitizing dyes, sensitizing pigments, or charge generation agents are dispersed or added together with a binder, or adjacent to a charge generation layer, together with a binder. It can be made as a laminated photoreceptor. In the present invention, when the enamine compound described above is used as a charge transfer layer of a functionally separated photoreceptor, it is possible to obtain a photoreceptor with particularly high sensitivity, less electrical fatigue during repeated use, and excellent light resistance. . As the layer structure of a functionally separated photoreceptor, a conductive layer, a charge generation layer, and a charge transfer layer are essential, and a barrier layer and a protective layer can be provided as necessary. The conductive layer, charge generation layer, and charge transfer layer may be stacked in any order, but the charge generation layer and charge transfer layer must be adjacent to each other. As the conductive layer, conventionally used conductive materials such as aluminum plates, aluminum-deposited plastics, metal plates coated with conductive paint, plastic materials, etc. can be used. As the charge generation material used in the charge generation layer, any material can be used as long as it absorbs light and generates charge carriers with high efficiency. Preferred materials include selenium, selenium, etc.
Inorganic materials such as tellurium and cadmium sulfide, and organic materials such as pyrylium salts, squarylium salts, azo pigments, cyanine pigments, quinone pigments, and phthalocyanine pigments can be used. These materials are formed into a charge generating layer by vapor deposition or coating from a dispersion. The thickness of this charge generation layer can range from 0.01 to 5μ. A charge transport layer is provided on the charge generation layer provided by any of the above methods.The enamine compound of the present invention is dissolved in an organic solvent together with a suitable binder, then applied and dried to form the charge transport layer. shall be. As the binder, acrylic resin, polycarbonate resin, polyester resin, polysulfone resin, etc. can be used. The ratio of the enamine compound of the present invention to the binder can be in the range of 2 parts by weight to 0.5 parts by weight per 1 part by weight of enamine. The thickness of the charge transfer layer may range from 5 to 30 microns. (Action of the invention) The electrophotographic photoreceptor thus obtained is
It can be applied to many fields such as electrophotographic copying machines, laser printers, LED printers, LCD printers, electrophotographic master plates, and electrophotographic microfilm. The photosensitive characteristics of the obtained photoconductor were as follows: Kawaguchi Electric SP
It is evaluated using the −428 type testing machine as follows. First, the photoreceptor is charged with -5.6KV corona discharge, left in a dark place until a constant voltage is reached, and then a tungsten lamp is used to irradiate the photoreceptor surface with light that produces 20 lux to increase the surface potential. Measure the time until it becomes 1/2 of the value before irradiation, and calculate the product with the illuminance:
Sensitivity is expressed in lux and seconds. In addition, spectral sensitivity is the product of the energy intensity μW/cm ³ of the photoreceptor surface of the spectral light and the time it takes for the surface potential to decrease to 1/2, which is the halved exposure energy μJule/cm ³
The reciprocal of this is called the spectral sensitivity. Fatigue characteristics during repeated use were similarly measured using Kawaguchi Electric's SP-428 type testing machine at -5.6KV.
The surface of the photoreceptor is charged by corona discharge at a corona linear velocity of 20 m/mm, left for 0.5 seconds, and the charged potential V _O at that time is measured. Subsequently, light with a surface illuminance of 500 lux is irradiated onto the surface of the photoreceptor for 0.5 seconds. Repeat this operation for 2.5 seconds/cycle. Such operations are repeated, and changes in chargeability (V _O ) and residual potential (V _R ) due to repetition are observed to evaluate fatigue characteristics as cyclic characteristics. It has been found that the electrophotographic photoreceptor according to the present invention has superior sensitivity and repeatability characteristics compared to conventional photoreceptors. (Example) Hereinafter, the details of the present invention will be explained with reference to Examples, Comparative Examples, and Synthesis Examples. In these Examples, Comparative Examples, and Synthesis Examples, parts represent parts by weight, and % represents weight %. Synthesis Example 1 Synthesis of enamine compound 2,2-(4,4'-
dimethoxydiphenyl)acetaldehyde 2.66g
After adding 50 ml of the reaction solvent toluene and dissolving with stirring, 1.77 g of 4,4'-ditolylamine was added, and further 0.1 g of para-toluenesulfonic acid was added, and the mixture was heated under the boiling point of toluene for 2 hours while stirring. After the reaction is completed, the reaction solution is cooled, washed with water, dehydrated, and toluene removed, followed by column separation (solvent: toluene, packing material Wako Gel C-200),
After recrystallization, white crystals are obtained with a content of 83 mol%. The structure of the obtained crystals will be confirmed by NMR analysis and elemental analysis. ○B NMR analysis (CDCL ₃ ) Peak position 2.21 (S, 6H), 3.75 (D,
6H), (ppm) 6.55-7.2 (M, 17H) ○B Melting point 124.0℃ ○C Elemental analysis value Carbon% Hydrogen% Nitrogen% Theoretical value 82.76 6.67 3.21 Measured value 82.69 6.57 3.25 Synthesis examples 2, 3 Same as synthesis example 1 An enamine compound is synthesized by the following reaction procedure. However, it is synthesized by reacting the following amine compound. Synthesis Example 2 1.77 g of 3,3'-ditolylamine was added and the same procedure was carried out, resulting in a yield of 67 mol%. Synthesis Example 3 1.52 g of diphenylamine was added and the same procedure was carried out, resulting in a yield of 85 mol%. Synthesis Example 4 An enamine compound is synthesized using the same reaction procedure as in Synthesis Example 1. However, aldehyde compounds are 2,2-
The amine compound is synthesized by reacting 1.76 g of (4,4'-diethoxydiphenyl)acetaldehyde with 1.17 g of 4,4'-ditolylamine. Yield 72 mol%
It is. Synthesis Example 5 An enamine compound is synthesized using the same procedure as in Synthesis Example 4, but the amine compound is 3,3'-ditolylamine.
It was synthesized by reacting with 1.17g. The yield is 62 mol%. Synthesis Example 6 An enamine compound was synthesized in the same manner as in Synthesis Example 4, but the amine compound was synthesized by reacting with 1.01 g of diphenylamine. The yield is 71 mol%. Synthesis Examples 2 to 6 are summarized above, and the results of NMR analysis and elemental analysis are shown in Table 1.

【table】

[Table] Example 1 Creation of a charge generation layer in the production of a functionally separated photoreceptor A 1% methanol solution of Toray's soluble polyamide (CM4001) was coated on a 100μ thick aluminum plate and dried, forming a barrier layer with a thickness of 0.05μ. Layers were provided. A charge generation layer as described below was provided on this barrier layer. 1% of chlordian blue represented by the above formula was added to tetrachloroethane, and 0.5% of butyral resin was added and dispersed in a ball mill. This dispersion was coated on the aluminum plate provided with the barrier layer and dried to form a charge generation layer with a thickness of 0.2 μm. (b) 1 g of squarylium with the following structure is 30
ml of tetrahydrofuran and dispersed in a ball mill to create a dispersion. It was coated and dried in the same manner as in (a) to create a charge generation layer with a thickness of 0.01 μm. (c) Vanadyl phthalocyanine was evaporated to a thickness of 1000 Å on the aluminum substrate on which the barrier layer was provided to create a charge generation layer. (d) Chloraluminum phthalocyanine chloride was deposited to a thickness of 500 Å on the aluminum plate provided with the barrier layer. This vapor-deposited film is
A charge generation layer was created by immersing it in 50 ml of toluene containing 500 ppm of water and leaving it at room temperature for 30 minutes. (e) 1 part of copper phthalocyanine (manufactured by Toyo Ink Co., Ltd., Lionol ES), 0.5 part of acrylic resin (manufactured by Dainippon Ink Co., Ltd., Acrydik A-801) 1.2 parts
- Add to dichloroethane to make 5%,
Thoroughly disperse in a ball mill. Dilute the milling solution with 1,2-dichloroethane to a solids concentration of 0.75%. This dispersion was coated on an aluminum plate with a barrier layer and dried to a thickness of 1000 Å.
A charge generation layer was prepared. Example 2 Preparation of coating liquid for charge transfer layer The enamines prepared in Synthesis Examples 1 to 6 were combined with the following binders at a ratio of 1 part to 1 part, mixed together, and dissolved in 10 parts of 1,2-dichloroethane. A coating solution for charge transfer layer was prepared. () Methyl methacrylate resin (Asahi Kasei Delpet) () Polycarbonate resin (Mitsubishi Gas Chemical Iupilon E-2000) () Styrene acrylic resin (Nippon Steel Chemical MS
-600) Examples 3 to 92 The coating solution prepared in Example 2 was applied at 70°C onto the charge generation layer prepared in (a) to (e) of Example 1,
After removing the solvent and pre-drying, it was further dried at 80℃ for 60 minutes.
Let dry for a minute. Under these conditions, a photoreceptor with a film thickness of about 15 μm was produced. Examples of photoreceptor preparation are shown in Table 2.

【table】

【table】

【table】

[Table] Comparative Examples 1 to 5 As a comparative example, a coating liquid was prepared in the same manner as in Example 6 using a hydrazone compound (formula) having the structure shown below. Photoreceptors prepared by combining this coating liquid and the charge generation layer of Example 5 were prepared in Comparative Examples 1 to 3.
5. Hydradone compound (comparative example) Coating liquid: 1 part of hydrazone compound, 1 part of polycarbonate (Iupilon E-2000 manufactured by Mitsubishi Gas Chemical)
Dissolve in 10 parts of 1,2-dichloroethane.

[Table] Performance of Examples and Comparative Examples The performance of each photoreceptor of Examples and Comparative Examples was measured using the measuring device described above (measurement using white light). The results are shown in Table 3.

【table】

[Table] Further, using a 790 nm spectral light source, measurements were made for each of the photoreceptors of Examples and Comparative Examples. The results are shown in Table 4.

【table】

[Table] (Effects of the Invention) The enamine compound represented by the general formula () of the present invention is a novel photoreceptor that has not existed before, and as specifically shown in the examples, its performance is the same as the initial performance. It was found that the photoreceptor not only had excellent performance after repeated use, but also had excellent sensitivity and repeated durability.

Claims (1)

[Claims] 1. In the photosensitive layer formed on the conductive support,
An electrophotographic photoreceptor comprising an enamine compound represented by the following general formula () as a charge carrier transfer agent. (However, R ₁ represents a methyl or ethyl group, and R ₂ represents a methyl group substituted at the para or meta position, or a hydrogen atom.)