JPH04214567A - Electrophotographic sensitive material - Google Patents

Abstract

PURPOSE:To obtain high sensitivity and small residual potential and to improve pre-exposure characteristics and characteristics for repeated use by providing a photosensitive layer containing a specified azo pigment on a conductive supporting body. CONSTITUTION:A photosensitive layer containing an azo pigment expressed by formula I is formed on a conductive supporting body. In the formula I, X is 1-4 valent org. residual group, n is an integer from 1 to 4, R1 is hydrogen atom, alkyl group, alkoxy group, aryl group, halogen atom, cyano group or nitro group, R2 is hydrogen atom, alkyl group or halogen atom, and l and m are integers from 1 to 4. Namely, the excellent carrier producing ability of an azo pigment is used as the carrier producing material for functional- separating type electrophotographic sensitive material in which each production and transfer of carrier is performed by the respective material different from the other.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to an electrophotographic photoreceptor, and more particularly, to an electrophotographic photoreceptor having a photosensitive layer containing a novel azo pigment. More specifically, the present invention relates to a highly durable electrophotographic photoreceptor that has high sensitivity and is suitable for repeated use.

[Prior art and its problems]

Conventionally, electrophotographic photoreceptors having a photosensitive layer containing an inorganic photoconductor such as selenium, zinc oxide, or cadmium sulfide as a main component have been widely known. However, these are not necessarily satisfactory in terms of sensitivity, thermal stability, moisture resistance, durability, etc. In particular, selenium and cadmium sulfide have limitations in manufacturing and handling due to their toxicity. . On the other hand, electrophotographic photoreceptors having a photosensitive layer containing an organic photoconductive compound as a main component are relatively easy to manufacture and generally have superior thermal stability compared to selenium photoreceptors. It has the following advantages and has attracted much attention in recent years. Such organic photoconductive compounds include poly-N-
Vinylcarbazole is well known, and this and 2,4
, 7-trinitro-9-fluorenone, and other Lewis acids, electrophotographic photoreceptors having a photosensitive layer containing a charge transfer complex as a main component are not necessarily satisfactory in terms of sensitivity and durability. On the other hand, in laminated or dispersed function-separated photoreceptors, in which the carrier generation function and the carrier movement function are assigned to separate substances, each material has a wide selection range, and the charging characteristics, sensitivity, and durability are improved. It has the advantage that an electrophotographic photoreceptor having arbitrary electrophotographic properties can be produced relatively easily. Conventionally, various carrier-generating substances or carrier-transferring substances have been proposed. For example, an electrophotographic photoreceptor has been put into practical use that has a photosensitive layer that combines a carrier generation layer made of amorphous selenium and a carrier transfer layer mainly composed of poly-N-vinylcarbazole. However, the carrier generation layer made of amorphous selenium has the disadvantage of poor durability. In addition, various proposals have been made to use organic dyes and pigments as carrier-generating substances. Showa 52-42
Publication No. 41, JP-A-54-46558, JP-A No. 5
6-11945 and the like are already known. However, these azo pigments are not necessarily satisfactory in characteristics such as sensitivity, residual potential, and stability upon repeated use.

[Purpose of the invention]

An object of the present invention is to provide an electrophotographic photoreceptor with high sensitivity, low residual potential, and excellent pre-exposure characteristics and repeated use characteristics.

[Structure of the invention]

The above object of the present invention is to provide the following general formula [
This was achieved by an electrophotographic photoreceptor characterized by having a photosensitive layer containing an azo pigment represented by [I]. General formula [I] [wherein, R2: represents a hydrogen atom, an alkyl group, or a halogen atom; 1 and m: represent an integer of 1 to 4; ] That is, in the present invention, by using the azo pigment represented by the general formula [I] as a photoconductive substance constituting the photosensitive layer of an electrophotographic photoreceptor, it is also possible to obtain an excellent carrier for the azo pigment of the present invention. By utilizing only the generation ability and using it as a carrier generation material in a so-called function-separated electrophotographic photoreceptor in which carrier generation and transfer are performed using separate substances, the film has excellent physical properties, such as charge retention, sensitivity, and An electrophotographic photosensitive material that has excellent electrophotographic properties such as residual potential, has little fatigue deterioration even after repeated use, and exhibits stable properties without changing the above-mentioned properties even when exposed to heat or light. It is possible to create a body. In the general formula [I], X is benzene, naphthalene, fluorene, anthracene, anthraquinone,
Hydrocarbon aromatic rings such as fluorenone, pyrene, and phenanthrene; heteroaromatic rings such as furan, thiophene, pyridine, indole, benzothiazole, carbazole, pyrazole, and dibenzothiophene; Those bonded with family groups, such as triphenylamine, biphenyl, terphenyl, binaphthyl, diphenyloxadiazole,
Examples include diphenyl sulfone, diphenylmethane, diphenyl ether, stilbene, distyrylbenzene, distyrylcarbazole, and distyrylanthracene. Specific examples of R1 in general formula [I] include a hydrogen atom, an alkyl group such as methyl, ethyl, and isopropyl, an alkoxy group such as methoxy and ethoxy, an aryl group such as phenyl, tolyl, chlorophenyl, and methoxyphenyl; Specific examples of R2 include a hydrogen atom, an alkyl group such as methyl, ethyl, isopropyl, or a halogen atom such as chloro, brome, etc. Specific examples of the azo pigment useful in the present invention represented by the above general formula include those having the following structural formula. (A) When n=1 (monoazo compound) (B) When n=2 (
(D) In the case of n = 4 (tetrakis azo compound) The azo pigment represented by the above general formula [I] is represented by the following general formula [II] (wherein X and n are the general formula [I]) The amine represented by the formula [III] is diazotized by a conventional method, and then the coupler represented by the following general formula [III] (wherein R1 and R2, and l and m are the same as in the general formula [I]) and an alkali are diazotized. or once the diazonium salt of the amine of general formula [II] is isolated in the form of borofluoride salt or zinc chloride double salt, etc., in the presence of a suitable solvent (for example, N,N-dimethyl It can be easily synthesized by coupling reaction with a coupler of general formula [III] in the presence of an organic or inorganic alkali in formamide, dimethyl sulfoxide, ethanol, dioxane). Next, a method for synthesizing a representative example of the azo pigment used in the present invention will be shown. Synthesis Example (Exemplified Compound 58) (a) Synthesis of 6-hydroxyisoquino[2,1-a]perimidine Homophthalic anhydride obtained from homophthalic acid [O. S.
Coll. Vol. 3,450], 5.1 g of 1,8-naphthalenediamine, and 15 ml of acetic acid are heated and stirred at 120° C. for 3.5 hours in 60 ml of nitrobenzene. After returning the temperature to room temperature, the precipitated crystals were collected by filtration, washed with a small amount of nitrobenzene, further washed with methanol, and dried by heating under reduced pressure to obtain crystal 7. (a).
Obtain 79g. Melting point: 318-320°C, yield: 89%. (b) Synthesis of Exemplified Compound 58 252 mg of 2,5-bis(4-aminophenyl)-1,3,4-oxadiazole was dissolved in 20 cc of DMF, and 2.2 cc of 2N hydrochloric acid was added thereto while stirring. A solution of 145 mg of sodium nitrite dissolved in 1 cc of water was added dropwise at ℃, and the mixture was reacted for 30 minutes to obtain a tetrazonium salt. The thus obtained tetrazonium salt solution was mixed with 569 mg of the crystals of (a) and 18 cc of triethanolamine in DM.
A solution dissolved in 170 cc of F was added dropwise to the cooling and stirring medium, and after stirring for about 2 hours, the formed crystals were collected by filtration.
After washing with DMF, water, and acetone, 237 mg of target Exemplary Compound 58 crystals were obtained. Melting point: 330°C or higher, yield: 28%. Other azo pigments of the present invention can also be obtained according to the above synthesis example. The electrophotographic photoreceptor of the present invention contains the azo pigment in the photosensitive layer, and the azo pigment can be used in various embodiments. For example, azo pigment is used as a binder.
It can be used as a photoconductive layer by coating the dispersion on a conductive support. Alternatively, a photosensitive layer can be formed by dispersing an azo pigment as a charge generating agent in a charge transporting material and coating this dispersed mixture on a conductive support. In yet another embodiment, it can be used as a laminated photoreceptor in which a charge generation layer containing an azo pigment as a charge generation agent is provided on a conductive support, and a charge transport layer is provided thereon. In this case, the charge generation layer may be formed by depositing an azo pigment on the conductive support, or by dispersing the azo pigment in a binder resin and coating the dispersion. . Examples of the binder resin used for dispersing the charge generating agent in the above embodiment include polyester resin, acrylic resin, styrene resin, silicone resin, alkyd resin, vinyl chloride-vinyl acetate copolymer resin, and styrene-butadiene copolymer resin. Polyvinyl acetal resin, diallyl phthalate resin, polysulfone resin, polycarbonate resin, acetic acid-bi-crotonic acid copolymer resin, polyarylate resin, butyral resin, styrene-maleic anhydride copolymer resin, rosin-phenol modified resin, casein, etc. can be,
These can be used alone or in combination as a copolymer. The amount of these binders to be used is 0.1 to 5 times the weight of the azo pigment, preferably 0.2 to 3 times. In addition, as the charge transport material forming the charge transport layer,
Known conductive compounds can be used. For example, hole transport materials include polyvinylcarbazole, phenanthrene, N-ethylcarbazole, 2,5-diphenyl-1,3,4-oxadiazole, 2,5-bis(4
-diethylaminophenyl)-1,3,4-oxadiazole, 4,4'-bis(diethylamino)-2,2'
-dimethyltriphenylmethane, 2,4,5-tris(
p-diethylaminophenyl)oxazole, 2,5-
Bis(p-diethylaminophenyl)-1,3,4-triazole, 1-phenyl-3-(p-diethylaminostyryl)-5-(p-diethylaminophenyl)-2
-Pyrazoline, p-diethylaminobenzaldehyde=
diphenylhydrazone, N-ethylcarbazole-3-
Examples include carbaldehyde = diphenylhydrazone, and examples of electron transport substances include 2-nitro-9-fluorenone, 2,7-dinitro-9-fluorenone, 2,4,
Examples include 7-trinitro-9-fluorenone, 2-nitrobenzothiophene, dinitroanthracene, dinitroacridine, dinitroanthraquinone, and the like. These charge transport substances can be used by being dispersed or dissolved in a binder resin, and the resins mentioned above can be used as the binder resin. The binder is added in an amount of 0.1 to 10 times the weight of the charge transport material, preferably 0.2 to 5 times the weight of the charge transport material. Examples of the conductive support used for producing the photoreceptor of the present invention include a metal plate, conductive paper, conductive processed plastic film, metallized film, metal cylinder, and plastic cylinder treated with metallization or metal foil. There is. Examples of solvents used for coating these supports by dispersing or dissolving azo pigments and charge transport substances together with binders include toluene, xylene, monochlorobenzene, chloroform, dichloroethane, trichloroethylene, methylene chloride, Dioxane, tetrahydrofuran, ethyl acetate, butyl acetate, methyl cellosolve,
Methyl cellosolve acetate, cyclohexanone, methyl ethyl ketone, dimethyl formamide, dimethyl sulfoxide, ethyl alcohol, propyl alcohol,
Butyl alcohol etc.

【Example】

Next, examples of the present invention will be shown. Example 1 Exemplary pigment 58 according to the present invention and the following pigments R-1, R-2, R-3 and R-4 of the structural formulas for comparison were each given as 1.
Part by weight, polyarylate resin (Unitika U-100)
1 part by weight was mixed with 100 parts by weight of dichloroethane and dispersed together with glass beads for 2 hours using a paint conditioner device. The pigment dispersion thus obtained was applied to an aluminum support for PS plate (anodized one) using a wire bar.
(manufactured by Agfa), each with a film thickness of approximately 0.2 to 0.
．． A 3 micron charge generation layer was provided. Next, a coating solution prepared by dissolving 1 part by weight of p-dibenzylaminobenzaldehyde=diphenylhydrazone and 1 part by weight of polyarylate resin in 10 parts by weight of dichloroethane as a charge transport material was applied onto the charge generation layer using a wire bar. A laminated photoreceptor having a charge transport layer with a thickness of 15 microns was prepared. Regarding this photoreceptor, an electrostatic recording tester (SP- manufactured by Kawaguchi Denki) was used.
428), the following characteristic tests were conducted. That is, a voltage of -6 KV is applied to the charger to charge the photosensitive layer by corona discharge for 5 seconds, and the potential Vo (V) at that time is
, find the potential Vd (V) after standing for 10 seconds, DD=Vd
/Vo×100 (%) was measured. In addition, the exposure amount E1/2 (lux seconds) required to attenuate the surface potential of the photosensitive layer by 1/2 was determined by irradiating light from a halogen lamp with the illumination intensity at the photosensitive layer being 30 lux. . Next, this photoreceptor was exposed to the light of a fluorescent lamp with an illuminance of 5000 lux for 5 minutes, left in a dark place for 30 seconds, and then subjected to the same characteristic test as above to determine the charging potential Vo (V), E1/2 (lu
x seconds) DD (%) was determined. The results are shown in Table 1. The upper row of Table 1 shows the initial characteristics, and the lower row shows the characteristics after light irradiation. From the results in Table 1, it can be seen that the photoreceptor using the azo pigment 58 of the present invention has very good charging potential Vo, sensitivity, and pre-exposure characteristics. Next, the surface potential after exposing these photoreceptors at an exposure amount of 50 lux·sec, that is, the residual potential E50 (V) was determined. Similar measurements were repeated 500 times. Further, irradiation exposure was performed for 0.3 seconds at 300 lux using a tungsten lamp as a light source to eliminate residual potential, so that the residual potential was completely reduced to zero. The results are shown in Table 2. From the results in Table 2, it can be seen that the photoreceptor using Azo Pigment 58 of the present invention has excellent repeated use characteristics. Example 2 Exemplary pigments 40, 45 and 56 of the present invention as described above,
For comparison, 2 parts by weight of each of the following pigments R-5, R-6, and R-7 (hereinafter referred to as margins), 1 part by weight of polycarbonate resin (Teijin Kasei Panlite-1250), and 50 parts by weight of dichloroethane were added.
In addition to parts by weight, it was dispersed in paint conditioner for 2 hours. This dispersion was applied onto the surface of an aluminum cylinder having an outer diameter of 60 mm by a cylindrical pull-up coating method. The film thickness was about 0.5 micron. On this charge generation layer, 1 part by weight of 1-phenyl-3-(p-diethylaminostyryl)-5-(p-diethylaminophenyl)pyrazoline, 2 parts by weight of polyester resin (Vylon-200) and 25 parts by weight of dichloroethane were added. A charge transport layer having a thickness of 15 microns was formed by applying the dissolved solution to produce a cylindrical photoreceptor. The charging potential Vo (V) and the general sensitivity E1/2 (lux sec) were determined for this photoreceptor in the same manner as in Example 1, and the initial charging potential after 10,000 repetitions of charging and exposure was determined. The difference ΔVo from the potential Vo was determined. The results are shown in Table 3. From the above results, it was confirmed that all of the photoreceptors of the present invention have higher general sensitivity than the comparative photoreceptors, and have excellent characteristics for repeated use. Example 3 Exemplary pigments 12, 60, 90, 188 according to the present invention
, and 199, and for comparison, 1 part by weight of the following pigment R-8 (hereinafter referred to as the margin), polyarylate resin (Unitika U-
100) was mixed with 100 parts by weight of dichloroethane and dispersed in the same manner as in Example (1) above to obtain a coating dispersion. An aluminum support for PS plates (anodized, manufactured by Agfa) was coated in the same manner as a support, and a charge generation layer of about 0.2 to 0.3 microns in thickness was provided on each. A coating solution prepared by dissolving 1 part by weight of p-dibenzylaminobenzaldehyde=diphenylhydrazone and 1 part by weight of polyarylate resin in 10 parts by weight of dichloroethane as a transport material was similarly applied onto the charge generation layer to form a charge film with a thickness of 15 microns. A laminated photoreceptor with a transport layer was produced. The white light sensitivity of this photoconductor was measured in the same manner as in Example 2, and the charging potential after repeated charging exposure 10,000 times was as follows:
The difference ΔVo from Vo and the residual potential ΔVr after static elimination were measured. The results are shown in Table 4. (The following is a blank space) From the above results, the photoreceptors of the present invention have excellent characteristics such as higher general sensitivity, better repeatability, and lower residual potential than those of comparative photoreceptors. confirmed.

【Effect of the invention】

As is clear from the above, the method of the present invention provides high sensitivity,
It is possible to obtain an electrophotographic photoreceptor having a low residual potential and excellent pre-exposure characteristics and repeated use characteristics.

Claims (1)

[Claims] 1. An electrophotographic photoreceptor comprising a photosensitive layer containing an azo pigment represented by the following general formula [I] on a conductive support. General formula [I] [wherein, R2: represents a hydrogen atom, an alkyl group, or a halogen atom; 1 and m: represent an integer of 1 to 4; ]