JPH0272370A - Electrophogoraphic sensitive body - Google Patents

Abstract

PURPOSE:To obtain the excellent photosensitive body which has high sensitivity and the stable characteristics at the time of repetitive use and has no toxicity by providing the photosensitive body contg. a specific compd. on a conductive base. CONSTITUTION:The photosensitive layer contg. the pyrazine deriv. expressed by formula I is provided. In formula I, Pz is expressed by formula II or formula III; R to R<4> denote alkyl group, aryl group all of R1 to R4 are preferably the same substituent. Such pyrazine compd. is used as the photoconductive material of the electrophotographic sensitive body and this pyrazine compd. is used a the carrier transfer material of the separated-function type electrophotographic sensitive body which executes carrier generation and transfer with respectively separate materials. The electrophotographic sensitive body which has excellent film properties, has excellent electrophotographic characteristics such as charge holding power, sensitivity and residual potential, has less fatigue deterioration when subjected to repetitive use and exhibits stable characteristics to heat or light as well is obtd. in this way.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to an electrophotographic photoreceptor, and more particularly to an electrophotographic photoreceptor having a photosensitive layer containing an organic photoconductive compound as a main component.

[Conventional technology]

Conventionally, electrophotographic photoreceptors (hereinafter sometimes simply referred to as photoreceptors) include selenium, zinc oxide, cadmium sulfide,
Inorganic photoreceptors having a photosensitive layer mainly composed of an inorganic photoconductive compound such as silicon have been widely used.

However, these are not necessarily satisfactory in terms of sensitivity, thermal stability, durability, etc.

For example, when selenium crystallizes, its properties as a photoreceptor deteriorate, making it difficult to manufacture.Also, selenium crystallizes due to heat, fingerprints, etc., and its performance as a photoreceptor deteriorates. In addition, cadmium sulfide has problems in moisture resistance and durability, and zinc oxide has problems in durability, etc.

In order to overcome these drawbacks of inorganic photoreceptors, research and development have been actively conducted in recent years on organic photoreceptors having photosensitive layers containing various organic photoconductive compounds as main components. For example, Japanese Patent Publication No. 50-10496 describes an organic photoreceptor having a photosensitive layer containing poly-N-vinyl rubazole and 2,4,7-trinitro-9-fluorenone. However, this photoreceptor is not necessarily satisfactory in sensitivity and durability. In order to improve these drawbacks, attempts have been made to develop organic photoreceptors with higher performance by assigning carrier generation and carrier transport functions to different substances. For such so-called functionally separated photoreceptors, each material can be selected from a wide range.
Many studies have been conducted since it is possible to relatively easily create a photoreceptor with arbitrary performance.

As a result, various azo compounds have been developed and put into practical use as carrier-generating substances. On the other hand, regarding carrier transport substances, for example, JP-A-51-94829, JP-A-52-
No. 72231, No. 53-27033, No. 55-520
A wide variety of substances have been proposed, as disclosed in No. 63, No. 58-65440, and the like.

[Problem that the invention seeks to solve]

Although some electrophotographic photoreceptors made using carrier transport materials such as those described above exhibit relatively excellent electrophotographic performance, their durability against light or electrical loads is weak, and their durability during repeated use is poor. It does not fully satisfy practical requirements because it causes instability and deterioration of performance.
There has been a desire to develop a carrier transport material that has even better carrier transport functionality and exhibits stable performance over long periods of use.

Furthermore, in recent years, gas lasers such as Ar lasers and He--Ne lasers and semiconductor lasers have begun to be used as light sources for photoreceptors. These lasers are characterized by time series ON/O
It is capable of FF and is particularly promising as a light source for copying machines and computer output printers that have image processing functions, including intelligent copiers. Among these, semiconductor lasers are attracting attention because their nature does not require electrical signal/optical signal conversion elements such as acoustic engineering elements, and they can be made smaller and lighter.

However, this semiconductor laser has a low output compared to a gas laser, and the oscillation wavelength is also long (approximately 780 nm or more), so the spectral sensitivity of conventional photoreceptors is too high on the short wavelength side. It is difficult to apply this method to devices that use lasers as light sources, and new improvements have been required for carrier transport materials.

The present invention has been made to solve these problems and provide an electrophotographic photoreceptor with extremely high durability.

[Means for solving problems]

The above problem can be solved by using an electrophotographic photoreceptor characterized in that the conductive support has a photosensitive layer containing a pyrazine derivative represented by the following general formula [I].

General formula [I] R, , R, , R and R6 represent an alkyl group or an aryl group.

Further, R, , R2, R, and R4 in the above general formula [1] are all the same substituent. It is preferable.

〔Effect of the invention〕

In the present invention, by using a pyrazine derivative represented by the general formula (I) as a photoconductive substance of an electrophotographic photoreceptor, this can be used for functionally separated electrophotography in which carrier generation and transport are performed using separate substances, respectively. By using it as a carrier transport material in the body, it has excellent film physical properties and excellent electrophotographic properties such as charge retention, sensitivity, and residual potential, and has little fatigue deterioration even after repeated use, and is resistant to heat or light. However, it is possible to create an electrophotographic photoreceptor that can exhibit stable characteristics.

Furthermore, the pyrazine derivative used in the present invention has the general formula [I
The pyrazine derivatives shown in ] can be used alone or in combination of two or more, and may also be used in combination with other photoconductive substances.

Specific examples of the pyrazine derivatives indicated by the maximum [■] above that are effective in the present invention include those having the following structural formula, but the compounds according to the present invention are not limited thereto.

Exemplified Compound (1) Among the compounds represented by general formula CI), those having the maximum structure [11] General formula (n) Exemplary Compound (2) Among the compounds represented by general formula [I], the maximum structure A compound having the general formula (III) (III) Although the compound of the present invention as described above has almost no photosensitivity to visible light as such, it can be sensitive to visible light by applying a certain sensitization method. It imparts electrical conductivity and can be used alone to form a photoreceptor. The first method is to add an organic dye and perform spectral sensitization (dye sensitization).

The second method is to form a charge transfer complex and sensitize it. Examples of dyes used for spectral sensitization include the following.

(1) Methyl violet, crystal violet,
Triphenylmethane dyes such as malachite green (2) Xanthine dyes such as erythrosine and rose bengal (3) Thiazine dyes such as methyl blue and methylene green (4) Oxazine dyes such as Cabri Blue and Melt Lab (5) Cyanine dyes such as thiacyanine and oxacyanine (6) Styryl dyes such as p-dimethylaminostyrylquinoline (7) Pyrylium salt dyes such as pyrylium salt, thiapyrylium salt, and benzopyrylium salt (8) 3.3'
-Dicarbazolylmethane dyes or electron-accepting substances that can be formed with the compound of the present invention and a charge transfer complex include 2.4
．． Lewis acids such as 7-trinitrofluorenone, 2,4,5.7-titranitrofluorenone, chloranil, and tetracyanoquinodimethane are used.

However, the compound of the present invention utilizes only its carrier transport ability and can be combined with other carrier-generating substances such as organic dyes, pigments, or inorganic photoconductors that have a carrier-generating ability.
The most favorable effect can be obtained when a functionally separated photoreceptor is used.

The dyes shown in (1) to (8) above are also useful as carrier-generating substances, and examples include those such as Saku.

(1) Azo dyes such as monoazo dyes, disazo dyes, and trisazo dyes (2) Perylene dyes such as perylenic anhydride and perylenic acid imide (3) Indigo dyes such as indigo and thioindigo (4) Anthraquinone and pyrenequinone and polycyclic quinones such as flavanfluorones (5) quinacridone dyes (6) bisbenzimidazole dyes (7) induthrone dyes (8) squarelylium dyes (9) metal phthalonanine, metal-free phthalonanine, etc. Lycyanine dye (10) Selenium, selenium alloy (H) CdS, CdSe, amorphous silicon inorganic photoconductor (12) Pyrylium salt dye, eutectic complex formed from thiapyrylium salt dye and polycarbonate In the present invention Since the triphenylamine derivative used does not have the ability to form a coating by itself, a photosensitive layer is formed by combining various binders.

Although any binder can be used here, it is preferable to use a hydrophobic, high dielectric constant, electrically insulating film-forming polymer. Examples of such high molecular weight polymers include, but are not limited to, the following.

(1) Polycarbonate (2) Polyester (3) Methacrylic resin (4) Acrylic resin (5) Polyvinyl chloride (6) Polyvinylidene chloride (7) Polystyrene (8) Polyvinyl acetate (9) Styrenic copolymer resin (e.g. styrene butadiene copolymer, styrene methyl methacrylate copolymer) (10) Acrylonitrile copolymer resin (e.g. vinylidene chloride-acrylonitrile copolymer, etc.) (11)
Vinyl chloride-vinyl acetate copolymer (12) Vinyl chloride-
Vinyl acetate-maleic anhydride copolymer (13) Silicone resin (14) Silicone resin-alkyd resin (15)
Phenol resin (e.g. phenol-formaldevit resin, m-cresol-formaldevit resin, etc.) (16) Styrene-alkyd resin (17) Poly-
N-Vinylcarbazole (18) Polyvinylbutyrol (19) Polyvinyl formal These binders can be used alone or as a mixture of two or more.

As shown in FIGS. 1 and 2, the photoreceptor of the present invention comprises a carrier-generating layer 2 containing a carrier-generating substance as a main component and a styryltriphenylamine derivative of the present invention on a conductive support l for carrier transport. A photosensitive layer 4 made of a laminate with a carrier transport layer 3 containing a substance as a main component is provided. Third
As shown in the drawings and FIG. 4, this photosensitive layer 4 may be provided through an intermediate layer 5 provided on a conductive support l. When the photosensitive layer 4 has a two-layer structure in this manner, an electrophotographic photoreceptor having the most excellent electrophotographic properties can be obtained.

Further, in the present invention, as shown in FIGS. 5 and 6, a photosensitive layer 4 formed by dispersing a fine particulate carrier generating substance 7 in a layer 6 containing the carrier transporting substance as a main component is used as a conductive support. It may be provided directly on the layer 1 or via an intermediate layer 5.

Preferable results can also be obtained by adding a sensitizing dye or a Lewis acid to a carrier transporting material and forming a single photosensitive layer 4 as shown in FIGS. 5 and 6, without using a carrier-generating material.

Here, when the photosensitive layer 4 is composed of two layers, the carrier generation layer 2
Which of the carrier transport layer 3 and the carrier transport layer 3 should be the upper layer is determined by whether the charging polarity is positive or negative. That is, in the case of a negatively charged photosensitive layer, the carrier transport layer 3
It is advantageous to use the carrier transport layer 3 as the upper layer because the styryltriphenylamine derivative in the carrier transport layer 3 is a substance that has a high transport ability for holes.

Further, the carrier generation layer 2 constituting the photosensitive layer 4 having a two-layer structure is
It can be formed directly on the conductive support 1 or the carrier transport layer 3, or after providing an intermediate layer such as an adhesive layer or a barrier layer as necessary, by the following method.

(1) Vacuum evaporation method (2) A method in which a solution of a carrier-generating substance dissolved in a suitable solvent is applied.

(3) A method in which a carrier-generating substance is made into fine particles in a dispersion medium using a ball mill, a homomixer, etc., and a dispersion obtained by mixing and dispersing with a binder as necessary is applied.

The thickness of the carrier generation layer 2 formed in this way is
0. It is preferably 01 to 5 μl, more preferably 0.05 to 3 μm.

Further, the thickness of the carrier transport layer 3 can be changed as necessary, but it is usually preferably 5 to 30 μm.

The composition ratio in this carrier transport layer 3 is preferably 0.8 to IO parts by weight of the binder to 1 part by weight of the carrier transport material whose main component is the styryltriphenylamine derivative of the present invention. When forming the photosensitive layer 4 in which a fine powder carrier-generating substance is dispersed, it is preferable to use the binder in an amount of 51 L parts or less per 1 part by weight of the carrier-generating substance.

Further, when the carrier generation layer 2 is configured as a dispersed layer using a binder, it is preferable to use the binder in an amount of 5 parts by weight or less per 1 part by weight of the carrier generating substance.

As the conductive support l used in the construction of the electrophotographic photoreceptor of the present invention, the following are mainly used, but the invention is not limited thereto.

l) Metal plates such as aluminum plates and stainless steel plates.

2) A thin layer of metal such as aluminum, palladium, or gold is provided on a support such as paper or plastic film by lamination or vapor deposition.

3) A layer of a conductive compound such as a conductive polymer, indium oxide, or tin oxide is provided on a support such as paper or a plastic film by coating or vapor deposition.

For the intermediate layer 5 such as an adhesive layer or a barrier layer, in addition to the high molecular weight polymer used as the binder, gelatin,
casein, starch, polyvinyl alcohol, vinyl acetate,
Organic polymer substances such as ethyl cellulose and carboxymethyl cellulose, or aluminum oxide are used.

The photoreceptor of the present invention has the above-mentioned structure, and as is clear from the examples described later, it has excellent charging characteristics, sensitivity characteristics, and image forming characteristics.

〔Example〕

The present invention will be specifically explained below using Examples, but the embodiments of the present invention are not limited thereto.

Synthesis Example 1 Synthesis of Compound Example A-2 The bisazo compound represented by the general formula [I] of the present invention can be easily synthesized by a known method.

J., L., Leiserson, A., Weisberg.
er, Org, 5ynth,.

Co11. 4-chloroacetylacetanilide was synthesized according to the method described in VolI[I, 183 (1955), and a pyrazine compound was synthesized from it as described below with reference to JP-A-62-270623.

160g of p-chloroacetylacetanilide to 1.5
12 in dimethylacetoacide and cooled to 0°C. The above solution was saturated with dry ammonia, heated to room temperature for 2 hours, then heated to 68-70'O for 2 hours, and then heated to reflux conditions for 12 hours. While the reaction solution was still hot, 300 aα of water was added thereto, cooled to room temperature, and the formed crystals were separated by filtration. Yield was 350g.

This crystal is 2,5-bis(4-acetoacidophenyl)
It is pyrazine. When 1.2 ff of water was further added to the filtrate of the reaction solution, further crystals were precipitated. This is DMAC/Water-X
Recrystallization was performed using a mixed solvent of 27.6 g of crystals. This is 2,6-bis(4-acetoacidophenyl)pyrazine. 10.38 g (0.03 mol) of the 2,6-bis(4-acetoacidophenyl)pyrazine obtained here was dispersed in concentrated hydrochloric acid 120+I2 and heated under reflux for 4 hours. After cooling, the precipitated solid was separated by filtration. , dispersed in 200 m12 of water.

Solid caustic soda was added to make the mixture strongly alkaline, and the product was filtered off. The product was recrystallized from DMAC/water. Yield is 7.65g. This product is 2,5-,bis(
4-aminophenyl) pyrazine.

5.24 g (0.02 mol) of 2,5-bis(4-aminophenyl)pyrazine obtained above was added to 20 ml of ethanol.
12, 6.24 g of ethyl iodide was added dropwise, and the mixture was refluxed for 3 hours.

After reaching room temperature, add 10% sodium hydroxide solution to 10%
Add 0ml and stir for 1 hour. After that, extract with toluene,
After washing with water and distilling off the solvent, purification was performed using silica gel chromatography.

The yield of the target product obtained was 3.54 g.

The target product, 2,5-bis(4-diethylphenyl)pyrazine, was confirmed by FD mass spectroscopy.
The target was confirmed.

Example 1 Selenium was evaporated onto a conductive support consisting of a polyester film laminated with aluminum foil to a thickness of 0.5
A carrier generation layer of μm was formed.

On top of that, 2.6 parts by weight of Exemplified Compound A and 10 parts by weight of polycarbonate "Panlite L-12504 (manufactured by Kijin Kasei Co., Ltd.) were dissolved in 90 parts by weight of 1,2-dichloroethane, and this solution was dried. A carrier transport layer was formed by coating to a film thickness of 11 pm+, and an electrophotographic photoreceptor of the present invention was prepared.

Regarding this electrophotographic photoreceptor, electrostatic copying paper tester r
The electrophotographic properties were measured using a dynamic method using EPA-5100 Model J (manufactured by Kawaguchi Electric Seisakusho Co., Ltd.). That is, when the surface of the photosensitive layer of the photoreceptor is charged with a charging voltage of -6 KV for 5 seconds, the surface potential VA1 is then irradiated with light from a tungsten lamp so that the illumination intensity on the photoreceptor surface is 35f2ux, and the surface potential vA is reduced by half. Exposure amount required to attenuate (half-reduced exposure amount) E 'A (Qux
The surface potential (residual potential) Vi+ after irradiation with an exposure dose of -sec) and 30 (lux-sec) was determined.The same measurement was repeated 100 times.

Table 1 As is clear from this table, the electrophotographic photoreceptor of the present invention has sufficient charge retention ability, has high sensitivity, has a small residual potential, and maintains good characteristics even after repeated use. It has excellent physical properties.

Comparative Example 1 A comparative photoreceptor was prepared in the same manner as in Example 1 except for using Compound T-1 below instead of Exemplified Compound A-2 as a carrier transport material.

CH.

When this photoreceptor was measured in the same manner as in Example 1, the results shown in Table 2 were obtained.

As is clear from the results in Table 2 and above, the comparative photoreceptor was significantly inferior in stability during repeated use compared to the photoreceptor of the present invention of Example 1.

Examples 2 to 4 The electrophotographic photosensitive material of the present invention was produced in the same manner as in Example 1 except that exemplified compounds A-4, A-10, and A-12 were used as carrier generating substances in place of exemplified compound A-2. Created a body.

Electrophotographic photoreceptors of the present invention were prepared using these photoreceptors in the same manner as in Example I.

The initial characteristics of these photoreceptors were measured in the same manner as in Example 1, and the results shown in Table 3 were obtained.

Example 5 A 0.05 μm thick film made of vinyl chloride-vinyl acetate-maleic anhydride copolymer [S-LEC MF-104 (manufactured by Tsukisui Kagaku Co., Ltd.)] was deposited on a conductive support having aluminum deposited on a polyester film. An intermediate layer is provided, and on top of that, Dibrom Ansu Anthrone ``Monolite Red 2 YJ
(C, 1, NO, 59300 manufactured by IC1) was added to 30 parts by weight of 1,2-dichloroethane and dispersed in a ball mill. Polycarbonate "Panlite L-1250J (manufactured by Kijin Kasei Co., Ltd.) was added to the resulting dispersion. A carrier-generating layer was formed by dissolving 1.5 parts by weight of a coating solution and thoroughly mixing the coating solution so that the film thickness after drying was 2 μI.

On top of that, a solution of 10.6 parts by weight of Exemplary Compound A and 10 parts by weight of polyester "Vylon 200J (manufactured by Toyobo Co., Ltd.) dissolved in 90 parts by weight of 1,2-dichloroethane was dried to give a film thickness of 11 μm. The electrophotographic photoreceptor of the present invention was prepared by applying the following coating to form a gear transport layer.

Measurements were carried out on this photoreceptor in the same manner as in Example 1, and the results shown in Table 4 were obtained.

Comparative Example 2 A comparative photoreceptor was prepared in the same manner as in Example 5, except that Compound T-2 below was used instead of Exemplary Compound A-10 as a carrier transport material.

When this comparative photoreceptor was measured in the same manner as in Example 1, the results shown in Table 5 were obtained.

As is clear from the results in Table 5 and above, the comparative photoreceptor was significantly inferior in sensitivity and repeated stability compared to the compound of the invention.

Example 6 Polyester “Vylon 200J” was placed on a conductive support made by laminating aluminum foil on a polyester film.
(manufactured by Toyo Boseki Co., Ltd.) with a thickness of 0.1 μm was provided.

As a carrier generating substance, a solution prepared by dispersing 1 part by weight of an azo pigment represented by the following structural formula in 60 parts by weight of 1,2-dichloroethane was applied on top of the carrier-generating substance so that the film thickness after drying was 0.3 μm. A carrier generation layer was formed.

Furthermore, 13.6 parts by weight of Exemplified Compound A-1 and 10 parts by weight of polycarbonate resin rZ-200J (manufactured by Mitsubishi Gas Chemical Co., Ltd.)
parts by weight were dissolved in 90 parts by weight of 1,2-dichloroethane, and the solution was applied so that the film thickness after drying was 20 μm to form a carrier transport layer, thereby producing an electrophotographic photoreceptor of the present invention. . The initial characteristics of this photoreceptor were measured in the same manner as in Example 1, and found to be VA-1280v.
E'A -3,3ffux-sea and V m =
It was Ov.

Example 7 An electrophotographic photoreceptor of the present invention was prepared in the same manner as in Example 6 except that the following compound was used as a carrier generating substance.

Also, this photoreceptor is used in an electrophotographic copying machine r U-B ix15
50MRJ (manufactured by Konica Corporation) and a live copy test was carried out, and a clear copy image was obtained that was faithful to the original image, had high contrast, excellent gradation, and quality. Even after repeating this process 5,000 times, a copy image as good as the initial one was obtained.

The initial characteristics of this photoreceptor are ■I-1230V, EIA
-3 (iQux-see, V * = 10v.
A photocopying test was carried out by attaching the copying machine to an M RJ (manufactured by Konica Corporation), and even after repeating it 5000 times, a copy image as good as the initial copy was obtained.

Example 8 The pyrazine derivative according to the present invention has particularly excellent performance as a carrier transport material for a photoreceptor for a semiconductor laser printer. In fact, we produced a photoreceptor for a semiconductor laser as shown below and obtained good results.

On an aluminum drum with an outer diameter of 10 cm as a conductive support, a 0.0 mm thick film made of vinyl chloride-vinyl acetate-maleic anhydride copolymer "S-LEC MF-IU (manufactured by I-Sui Kagaku Co., Ltd.)" was placed on an aluminum drum with an outer diameter of 10 cm as a conductive support.
05 μl of intermediate layer was provided, and 2 g of the above compound (chlordian blue) was added on top of 110 μl of 1,2-dichloroethane.
A carrier-generating layer was formed by coating a dispersion solution mixed with +a(l) and dispersed in 24 μl using a ball mill so that the film thickness after drying was 0.1 μm.On this carrier-generating layer, Exemplary compound B-4.6g and methacrylic resin "Acrivet" (manufactured by Mitsubishi Rayon Co., Ltd.) log is 1.2
- A solution dissolved in dichloroethane 70jnQ was applied so that the film thickness after drying was 18 μm to form a carrier transport layer, thereby producing an electrophotographic photoreceptor of the present invention.

The laser beam intensity on the surface of the photoreceptor of the present invention is 0-85 m.
A live photo test was conducted using an experimental machine equipped with a W semiconductor laser (790 nm).

After the surface of the photoreceptor was charged to -6 KV, it was exposed to laser light and reverse development was performed at a bias voltage of -250 V, and a good image without fog was obtained.

Comparative Example 3 A comparative photoreceptor was obtained in the same manner as in Example 8, except that the following Exemplified Compound T-3 was used in place of Exemplified Compound B-4.

Using this comparative photoreceptor, a photo-taking test using a semiconductor laser was conducted in the same manner as in Example 8, but there was a lot of fog and good images could not be obtained.

〔Effect of the invention〕

According to the present invention, it is possible to obtain an excellent photoreceptor that has high sensitivity, extremely stable characteristics during repeated use, and has no toxicity problem.

[Brief explanation of the drawing]

1 to 6 are sectional views showing examples of the mechanical structure of the electrophotographic photoreceptor of the present invention, respectively. ■... Conductive support 2... Carrier generation layer 3... Carrier transport layer 4... Photosensitive layer 5... Intermediate layer 6... Layer containing carrier transport substance 7... Carrier Generated substances Figure 1 Figure 2 Figure 5 Figure 6

Claims (4)

[Claims] (1) An electrophotographic photoreceptor characterized by having a photosensitive layer containing a compound represented by the following general formula [I] on a conductive support. General formula [I] ▲There are mathematical formulas, chemical formulas, tables, etc.▼ [In the formula, Pz represents ▲There are mathematical formulas, chemical formulas, tables, etc.▼ or ▲There are mathematical formulas, chemical formulas, tables, etc.▼. R_1, R_2, R_3 and R_4 represent an alkyl group or an aryl group which may have a substituent. ] (2) R_1, R_2, R_3 in the above general formula [I]
The electrophotographic photoreceptor according to claim 1, wherein all of R_4 and R_4 are the same substituent. (3) The photosensitive layer contains a carrier-generating substance and a carrier-transporting substance, and the carrier-transporting substance has the general formula [
The electrophotographic photoreceptor according to claim 1 or 2, which uses a compound represented by I]. (4) The electrophotographic photoreceptor according to claim 1, wherein the photosensitive layer has a laminated structure of a carrier generation layer containing a carrier generation substance and a carrier transport layer containing a carrier transport substance.