JPH0363744B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an electrophotographic photoreceptor, and more particularly to an electrophotographic photoreceptor that prevents deterioration of electrophotographic characteristics caused by ultraviolet irradiation. Until now, inorganic substances such as selenium, cadmium sulfide, and zinc sulfide have been known as photoconductive substances used in electrophotographic photoreceptors, but on the other hand, various organic photoconductive polymers such as polyvinyl carbazole and hydrazone compounds have been used. , pyrazoline compounds, oxadiazoles, indole compounds, carbazole compounds, anthracene, pyrene, and other organic photoconductive materials have been proposed. In general, organic photoconductive materials are superior to inorganic photoconductive materials in terms of light weight and coatability, but their sensitivity is not sufficient, so various sensitization methods have been proposed. . Among several sensitization methods, for example, as disclosed in U.S. Pat. The method of sensitization is one of the effective methods. In such a functionally separated photosensitive layer, charge carriers injected from the charge generation layer into the charge transport layer can be transported to the vicinity of the surface without being trapped in the charge transport layer in the presence of an electric field. is necessary. However, in reality, when this type of photosensitive layer is repeatedly charged and exposed to light, an increase in bright area potential appears to be caused by the accumulation of traps in the charge transport layer. The inventors of the present invention have repeatedly investigated the above-mentioned problems and found that the charge transport substance contained in the charge transport layer undergoes an irreversible chemical change, especially near the surface layer, due to the action of ultraviolet rays, and this irreversible reaction occurs. They have come to the conclusion that the component traps and accumulates the charge carriers injected from the charge generation layer, so that the bright area potential gradually increases when used repeatedly. Further, such a phenomenon also occurs when the above-mentioned photosensitive layer is exposed to an environment containing ultraviolet rays, for example. For example, the photoreceptor may be exposed to external ultraviolet light before use, that is, before it is installed in a copier, and then the photoreceptor is installed in the copier and subjected to a normal image forming process that includes repeated charging and exposure steps. Then, the bright area potential gradually increases,
The resulting image tends to gradually become an image with large capri. Therefore, an object of the present invention is to provide an electrophotographic photoreceptor that eliminates the above-mentioned drawbacks. Another object of the present invention is to provide an electrophotographic photoreceptor in which irreversible chemical reactions within the charge transport layer caused by the action of ultraviolet rays are prevented. Another object of the present invention is to provide a functionally separated electrophotographic photoreceptor that suppresses the increase in bright area potential that occurs during repeated use. The object of the present invention is to provide an electrophotographic photoreceptor having a charge generation layer and a charge transport layer, wherein the charge transport layer has the following general formula (1). {In the formula, R ₁ represents an aryl group substituted with one or more hydroxy groups or alkoxy groups, or a heterocyclic group optionally substituted with one or more hydroxy groups or alkoxy groups, and R ₂ is It represents a hydrogen atom, an alkyl group, an aralkyl group, an aryl group, or an alkoxy group, and R ₃ is a hydrogen atom, an acyl group, a nitrile group, a carboxyl group, or a -
COOR ₅ (R ₅ represents a hydrogen atom or an alkyl group.)
and R ₄ represents a hydrogen atom or an alkyl group. } This is achieved by an electrophotographic photoreceptor characterized by containing an acrylic compound represented by the following. In the formula, the alkoxy group of R ₁ is methoxy,
Examples include groups such as ethoxy, propoxy and butoxy; aryl groups include phenyl, tolyl, xylyl and naphthyl; heterocyclic groups include monovalent residues derived from indoline rings etc. . Examples of the alkyl group of R ₂ include groups such as methyl, ethyl, propyl, cyclopentyl and cyclohexyl, and examples of the aralkyl group include groups such as benzyl, phenethyl and 1-phenylethyl;
Aryl groups include phenyl, tolyl, xylyl and naphthyl, and alkoxy groups include methoxy, ethoxy and propoxy. The alkyl group for _R4 is methyl, ethyl, propyl, butyl, amyl,
Groups such as hexyl, 2-ethylhexyl, octyl, nonyl and decyl may be mentioned. The alkyl group for R ₅ is methyl, ethyl, propyl, butyl, amyl, hexyl, 2-ethylhexyl,
Groups such as octyl, nonyl and decyl may be mentioned. In particular, in the present invention, acrylonitrile compounds are preferred. Specific examples of the acrylic compound used in the present invention are:
It is as follows. These ultraviolet absorbers may be used alone or in combination of two or more, or may be used in combination with other ultraviolet absorbers. In addition, these compounds are contained in the charge transport layer in an amount of 50 to 0.1 wt%, preferably 35 to 1 wt%.
It can be included in a proportion of The charge transport layer of the present invention includes chlorallyl, bromoanil, tetracyanoethylene, tetracyanoquinodimethane, 2,4,7-trinitro-9-fluorenone, 2,4,5,7-tetranitro-9-
Fluorenone, 2,4,7-trinitro-9-dicyanomethylenefluorenone, 2,4,5,7-
Electron-withdrawing substances such as tetranitroxanthone, 2,4,8-trinitrothioxanthone, polymerized products of these electron-withdrawing substances, or pyrene, N-ethylcarbazole, N-isopropylcarbazole, N-methyl-N- Phenylhydrazino-3-methylidene-9-ethylcarbazole, N,N-diphenylhydrazino-3-methylidene-9-ethylcarbazole, N,N-diphenylhydrazino-3-methylidene-10-ethylphenol Thiazine, N,N-diphenylhydrazino-
3-methylidene-10-ethylphenoxazine, P
-Diethylaminobenzaldehyde-N,N-diphenylhydrazone, P-diethylaminobenzaldehyde-N-α-naphthyl-N-phenylhydrazone, P-pyrrolidinopenzaldehyde-
N,N-diphenylhydrazone, 1,3,3-trimethylindolenine-ω-aldehyde-N,N
-diphenylhydrazone, P-diethylbenzaldehyde-3-methylbenzthiazolinone-2-
Hydrazones such as hydrazone, 2,5-bis(P
-diethylaminophenyl)-1,3,4-oxadiazole, 1-phenyl-3-(P-diethylaminostyryl)-5-(P-diethylaminophenyl)pyrazoline, 1-[quinolyl(2)]-3
-(P-diethylaminostyryl)-5-(P-diethylaminophenyl)pyrazoline, 1-[pyridyl(2)]-3-(P-diethylaminostyryl)
-5-(P-diethylaminophenyl)pyrazoline, 1-[6-methoxy-pyridyl (2)]-3-
(P-diethylaminostyryl)-5-(P-diethylaminophenyl)pyrazoline, 1-[pyridyl(3)]-3-(P-diethylaminostyryl)-
5-(P-diethylaminophenyl)pyrazoline,
1-[Lepidyl (2)]-3-(P-diethylaminostyryl)-5-(P-diethylaminophenyl)
Pyrazoline, 1-[pyridyl(2)]-3-(P-diethylaminostyl)-4-methyl-5-(P-diethylaminophenyl)pyrazoline, 1-[pyridyl(2)]-3-(α-methyl -P-diethylaminostyryl)-5-(P-diethylaminophenyl)pyrazoline, 1-phenyl-3-(P-diethylaminostyryl)-4-methyl-5-(P-diethylaminophenyl)pyrazoline, 1-phenyl- Pyrazolines such as 3-(α-benzyl-P-diethylaminostyryl)-5-(P-diethylaminophenyl)pyrazoline and spiropyrazoline, 2-(P-diethylaminostyryl)-6-diethylaminobenzoxazole, 2-(P- oxazole compounds such as diethylaminophenyl)-4-(P-dimethylaminophenyl)-5-(2-chlorophenyl)oxazole, thiazole compounds such as 2-(P-diethylaminostyryl)-6-diethylaminobenzothiazole, triarylmethane compounds such as bis(4-diethylamino-2-methylphenyl)-phenylmethane,
1,1-bis(4-N,N-diethylamino-2
-methylphenyl)heptane, 1,1,2,2-
Tetrakis (4-N,N-dimethylamino-2-
Polyarylalkanes such as methylphenyl)ethane, triphenylamine, poly N-vinylcarbazole, polyvinylpyrene, polyvinylanthracene, polyvinylacridine, poly-9-vinylphenylanthracene, pyrene-formaldehyde resin, ethylcarbazole formaldehyde resin, etc. It can contain a pore-transporting substance. Particularly, the compound of the present invention is effective when a hydrazone compound having a large absorption coefficient for ultraviolet rays is used as a charge transport material. The charge transport layer can be formed by applying a solution prepared by dissolving the above-mentioned charge transport substance and acrylic compound together with a binder resin in a suitable solvent and drying the solution. At this time, the acrylic compound may be contained in the binder resin in advance, or the coated film may be immersed in a solution of the acrylic compound and the acrylic compound may be added only near the surface of the film, especially near the surface of about 5 μm. You may let them. As the binder resin used for the charge transport layer,
Polyarylate resin, polysulfone resin, polyamide resin, acrylic resin, acrylonitrile resin, methacrylic resin, vinyl chloride resin, vinyl acetate resin, phenol resin, epoxy resin, polyester resin, alkyd resin, polycarbonate,
Examples of polyurethane or copolymer resins containing two or more repeating units of these resins include styrene-butadiene copolymer, styrene-acrylonitrile copolymer, and styrene-maleic acid copolymer. In addition to such insulating polymers, organic photoconductive polymers such as polyvinylcarbazole, polyvinylanthracene, and polyvinylpyrene can also be used. Since the charge transport layer has a limit in the distance over which charge carriers can be transported, it is impossible to make the film thicker than necessary. Typically it is between 5 microns and 30 microns, with a preferred range between 8 microns and 20 microns. When forming a charge transport layer by coating, coating methods such as dip coating method, spray coating method, spinner coating method, bead coating method, Meyer bar coating method, blade coating method, roller coating method, curtain coating method, etc. This can be done using the law. The charge transport layer of the present invention can contain various additives. Such additives include diphenyl, dienyl chloride, O-terphenyl,
P-terphenyl, dibutyl phthalate, dimethyl glycol phthalate, dioctyl phthalate, triphenyl phosphoric acid, matylnaphthalene, benzophenone, chlorinated paraffin, dilaurylthiopropionate, 3,5-dinitrosalicylic acid,
Examples include various fluorocarbons. The charge generation layer used in the present invention includes selenium, selenium-tellurium, pyrylium, thiopyrylium dyes,
Phthalocyanine pigments anthorone pigments, dibenzpyrenequinone pigments, pyranthrone pigments, trisazo pigments, disazo pigments, azo pigments, indigo pigments, quinacridone pigments, asymmetric quinocyanine, quinocyanine, or amorphous as described in JP-A-54-143645. Separate deposited layers or resin dispersion layers of charge generating materials such as silicon can be used. The charge generation layer contains as much of the organic photoconductor as possible in order to obtain sufficient absorbance and is preferably a thin film layer, for example less than 5 microns, in order to shorten the range of the generated charge carriers. teeth
A thin film layer having a thickness of 0.01 micron to 1 micron is preferable. This means that most of the incident light is absorbed by the charge generation layer and generates a large number of charge carriers, and that the generated charge carriers are not deactivated by recombination or trapping, and the charge transport layer This is due to the need to inject. Further, although this charge generation layer is provided between the charge transport layer and the conductive layer, it may be provided on the charge transport layer. A photosensitive layer having such a laminated structure of a charge generation layer and a charge transport layer is provided on a substrate having a conductive layer. As the substrate having the conductive layer, materials that are themselves conductive can be used, such as aluminum, aluminum composite, copper, zinc, stainless steel, vanadium, molybdenum, chromium, titanium, nickel, indium, gold, and platinum. In addition, plastics (e.g., polyethylene, polypropylene, polyvinyl chloride, polyethylene terephthalate, acrylic resin) have a layer formed by vacuum deposition of aluminum, aluminum alloy, indium oxide, tin oxide, indium oxide, tin monoxide alloy, etc. , polyethylene fluoride, etc.), conductive particles (e.g., carbon black,
A substrate made of plastic coated with silver particles (silver particles, etc.) together with a suitable binder, a substrate made of plastic or paper impregnated with conductive particles, a plastic containing a conductive polymer, etc. can be used. A subbing layer having barrier and adhesive functions can also be provided between the conductive layer and the photosensitive layer. The undercoat layer is made of casein, polyvinyl alcohol, nitrocellulose, ethylene-acrylic acid copolymer, polyamide (nylon 6, nylon 66, nylon
610, copolymerized nylon, alkoxymethylated nylon, etc.), polyurethane, gelatin, aluminum oxide, etc. The thickness of the undercoat layer is 0.1 micron to 5 micron.
Preferably, 0.5 micron to 3 micron is appropriate. The electrophotographic photoreceptor of the present invention can be used not only for electrophotographic copying machines, but also for laser printers,
It can also be widely used in electrophotographic applications such as CRT printers and electrophotographic plate making systems. According to the present invention, it is possible to effectively prevent various defects that occur when an electrophotographic photoreceptor is exposed to light rays containing ultraviolet rays, and it is possible to effectively prevent copying using an optical system that emits rays containing ultraviolet rays. The machine can also prevent various defects that occur when repeatedly charging and exposing to light. These effects and examples according to the present invention will be clarified below. Example 1 An ammonia aqueous solution of casein (11.2 g of casein, 1 g of 28% ammonia water, 222 g of water) was placed on an aluminum sheet.
ml) was applied with a Mayer bar so that the film thickness after drying was 1.0 microns, and dried. Then the structural formula 5 g of the disazo pigment was added to a solution prepared by dissolving 2 g of butyral resin (degree of butyralization: 63 mol %) in 95 ml of ethanol, and dispersed with an attritor for 2 hours. This dispersion was applied onto the previously formed casein layer using a Mayer bar so that the film thickness after drying was 0.2 microns, and dried to form a charge generation layer. Then, the structural formula 5 g of the hydrazone compound, 2 g of the acrylic compound (1) shown above, and 5 g of polymethyl methacrylate resin (number average molecular weight 100,000) were mixed with 70 ml of benzene.
and apply it onto the charge generation layer using a Mayer bar so that the film thickness after drying is 12 microns.
A dried charge transport layer was formed. The electrophotographic photoreceptor thus prepared was left in a room under fluorescent lamp illumination for 15 minutes, and then the fluctuations in bright area potential and dark area potential were measured when the photoreceptor was used repeatedly. For this measurement, an electrophotographic copying machine equipped with a -5.6 KV corona charger, an exposure optical system with an exposure amount of 15 lux-sec, a developer, a transfer charger, a static elimination exposure optical system, and a cleaner was used. The photoreceptor of this example was attached to the cylinder. This copying machine is configured to produce an image on transfer paper as the cylinder is driven. Using this copying machine, we measured the initial bright area potential (V _L ) and dark area potential (V _D ) of the photoreceptor of this example, and further measured the bright area potential (V _L ) when this photoreceptor was used 2000 times. ) and dark potential (V _D ) were measured. The results are shown in Table 1. On the other hand, as a comparative test, a comparative photoreceptor was created in exactly the same manner, except that the use of the acrylic compound used when creating the photoreceptor described above was omitted, and then used repeatedly in the same manner as described above. The fluctuations in the bright and dark potentials were measured at the same time. The results are also shown in Table 1.

[Table] Examples 2 to 6 Instead of the acrylic compound (1) used in Example 1, the acrylic compounds (4), (5), (8),
Five types of photoreceptors were prepared in the same manner as in Example 1, except that (9) and (10) were used, respectively. After leaving these photoreceptors in a room under fluorescent light illumination for 15 minutes, the same method as in Example 1 was carried out.
After 2000 cycles, changes in bright and dark potential were measured. These results are shown in Table 2.

[Table] Examples 7 to 9 N,N-diphenylhydrazino-3-methylidene-9-ethylcarbazole (Example 7), P -Diethylaminobenzaldehyde-N,N-diphenylhydrazone (Example 8)
and P-pyrrolidinobenzaldehyde-N,N
- Diphenylhydrazone (Example 9) was used in each case, but in the same manner as in Example 1.
A seed photoreceptor was created. After leaving these photoreceptors in a room under fluorescent light illumination for 15 minutes, the same method as in Example 1 was carried out.
After 2000 cycles, changes in bright and dark potential were measured. These results are shown in Table 3.

【table】

Claims (1)

[Scope of Claims] 1. In an electrophotographic photoreceptor having a charge generation layer and a charge transport layer, the charge transport layer has the following general formula (1). {In the formula, R ₁ represents an aryl group substituted with one or more hydroxy groups or alkoxy groups, or a heterocyclic group optionally substituted with one or more hydroxy groups or alkoxy groups, and R ₂ is It represents a hydrogen atom, an alkyl group, an aralkyl group, an aryl group, or an alkoxy group, and R ₃ is a hydrogen atom, an acyl group, a nitrile group, a carboxyl group, or a -
COOR ₅ (R ₅ represents a hydrogen atom or an alkyl group.)
and R ₄ represents a hydrogen atom or an alkyl group. } An electrophotographic photoreceptor comprising an acrylic compound represented by the following.