JPH0513507B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD The present invention relates to a new electrophotographic photosensitive material, and more particularly to a highly sensitive electrophotographic photoreceptor containing a metallocene compound having a specific molecular structure in a photoconductive layer. BACKGROUND ART Conventionally, pigments and dyes exhibiting photoconductivity have been published in numerous publications. For example, RCA Review Vol.23. 413～419
(1962.9) published on the photoconductivity of phthalocyanine pigments, and an electrophotographic photoreceptor using this phthalocyanine pigment was patented in the United States.
This is disclosed in Publication No. 3397086, Publication No. 3816118, etc. In addition, examples of organic semiconductors used in electrophotographic photoreceptors include US Pat. No. 4,315,983;
Publication No. 4327169 and Research Disclosure 20517
(1981.5), methine squaritate dye shown in US Pat. No. 3,824,099, US Pat. No. 3,898,084,
Examples include disazo dyes disclosed in Publication No. 4251613 and the like. Such organic semiconductors are easier to synthesize than inorganic semiconductors, and can be synthesized as compounds that are highly photoconductive to light in the required wavelength range. The electrophotographic photoreceptor formed on a transparent substrate is
Although it has the advantage of improved color sensitivity, there are very few that can be put to practical use in terms of sensitivity and durability. Problems to be Solved by the Invention The present inventors have completed the present invention as a result of intensive research aimed at improving the various drawbacks of organic semiconductor materials and obtaining a photoconductive material with excellent electrophotographic properties. A first object of the present invention is to provide a novel organic semiconductor coating. The second object is to provide an electrophotographic photoreceptor that can be used in all existing electrophotographic processes, improves the conventional drawbacks, and provides higher electrophotographic response gain. Means for Solving the Problems and Effects The present invention provides an electrophotographic photoreceptor having a conductive substrate and a photoconductive layer, wherein the photoconductive layer has the general formula However, in the formula, m is an integer of 0.1 or 2, A represents a sulfur atom or an oxygen atom, and B represents a benzothirium ring, a benzoxothiylium ring, a naphthothiylium ring, or a naphthothiylium ring which may have a substituent. Indicates the residues necessary to form a ring,
Substituents include lower alkyl groups such as methyl, ethyl, propyl or butyl, methoxy, ethoxy,
lower alkoxy groups such as propoxy or butoxy,
Examples include halogen atoms such as fluorine, chlorine, bromine or iodine, and functional groups such as nitro groups. M represents a metal element selected from Ti, V, Cr, Fe, Co, Ni and Rn, and X ^- represents an anionic functional group, specific examples include Cl ^- , Br ^- , I ^- , BF ^- ₄ ,
^Cl0-4 _, PF ^- ₆ ,

An electrophotographic photoreceptor characterized by containing a metallocene compound of the formula: CH ₃ SO ^- ₃ , C ₂ H ₅ SO ^- ₃ , CH ₃ SO ^- ₄ and other anions. A general method for producing the metallocene compound of general formula (I) used in the present invention is as follows: Synthesized using methods such as Specific examples of the metallocene compounds used in the present invention are listed below. The above exemplified compounds do not limit the scope of the claims of the present invention. The film containing the metallocene compound described above exhibits photoconductivity and can be used in the photosensitive layer of the electrophotographic photoreceptor described below. That is, in a specific example of the present invention, the metallocene compound of the general formula (I) is formed as a film on a conductive substrate by vacuum evaporation, or is dispersed in a suitable binder to form a film, thereby producing an electrophotographic sensitizer. body can be created. In a preferred embodiment of the present invention, the photoconductive coating described above can be applied as a charge generation layer in an electrophotographic photoreceptor in which the photosensitive layer of the electrophotographic photoreceptor is functionally separated into a charge generation layer and a charge transport layer. The charge generation layer contains as much of the above-mentioned photoconductive compound as possible in order to obtain sufficient absorbance, and is a thin film layer, for example, 5μ or less, preferably in order to shorten the range of the generated charge carriers. 0.01〜
A thin film layer having a thickness of 1 μm is preferable.
This means that most of the incident light is absorbed by the charge generation layer, producing many charge carriers;
Furthermore, this is due to the fact that the generated charge carriers need to be injected into the charge transport layer without being deactivated by recombination or trapping. The charge generation layer can be formed by dispersing the above-mentioned compound in a suitable binder and coating it on a conductive substrate, or it can be obtained by forming a vapor deposited film using a vacuum vapor deposition apparatus. I can do it. Binders that can be used to form the charge generating layer by coating can be selected from a wide variety of insulating resins, and can also be selected from organic photoconductive polymers such as poly-N-vinylcarbazole, polyvinylanthracene, and polyvinylpyrene. . Preferably polyvinyl butyral, polyarylate (condensation polymer of bisphenol A and phthalic acid, etc.), polycarbonate, polyester, phenoxy resin, polyvinyl acetate, acrylic resin, polyacrylamide, polyamide, polyvinylpyridine, cellulose resin, urethane resin, Examples include insulating resins such as epoxy resin, casein, polyvinyl alcohol, and polyvinylpyrrolidone. The resin contained in the charge generation layer is 80% by weight.
Below, preferably 40% by weight or less is suitable. Solvents that dissolve these resins vary depending on the type of resin, and are preferably selected from those that do not dissolve the charge transport layer or undercoat layer described below. Specific organic solvents include alcohols such as methanol, ethanol and isopropanol, ketones such as acetone, methyl ethyl ketone and cyclohexanone, N,N-dimethylformamide,
Amides such as N,N-dimethylacetamide,
Sulfoxides such as dimethyl sulfoxide, ethers such as tetrahydrofuran, dioxane, and ethylene glycol monomethyl ether, esters such as methyl acetate and ethyl acetate, chloroform,
methylene chloride, dichloroethylene, carbon tetrachloride,
Aliphatic halogenated hydrocarbons such as trichloroethylene, aromatics such as benzene, toluene, xylene, ligroin, monochlorobenzene, dichlorobenzene, etc. can be used. Coating can be carried out using coating methods such as dip coating, spray coating, spinner coating, bead coating, Meyer bar coating, blade coating, roller coating, and carting coating. For drying, it is preferable to dry to the touch at room temperature and then heat dry. Heat drying at 30-200℃ for 5 minutes
It can be carried out stationary or under ventilation for a period of 2 hours. The charge transport layer is electrically connected to the charge generation layer described above, and has the function of receiving charge carriers injected from the charge generation layer in the presence of an electric field and transporting these charge carriers to the surface. ing. At this time, this charge transport layer may be laminated on or under the charge generation layer. The substance that transports charge carriers in the charge transport layer (hereinafter referred to as charge transport substance) is preferably substantially insensitive to the wavelength range of electromagnetic waves to which the charge generation layer is sensitive. The term "electromagnetic waves" as used herein includes a broad definition of "light rays" including gamma rays, X-rays, ultraviolet rays, visible light, near infrared rays, infrared rays, far infrared rays, and the like. When the photosensitive wavelength range of the charge transport layer coincides with or overlaps that of the charge generation layer, charge carriers generated in both layers capture each other, resulting in a decrease in sensitivity. Charge transport substances include electron transport substances and hole transport substances, and electron transport substances include chloranil, 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-tetranitroxanthone, 2,4,
Examples include electron-withdrawing substances such as 8-trinitrothioxanthone, and polymerization of these electron-withdrawing substances. As the hole transport substance, 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-ethylphenothiazine, N,
N-diphenylhydrazino-3-methylidene-10
-Ethylphenoxazine, P-diethylaminobenzaldehyde-N,N-diphenylhydrazone, P-diethylaminobenzaldehyde-N-
α-Naphthyl-N-phenylhydrazone, P-pyrrolidinobenzaldehyde-N,N-diphenylhydrazone, 1,3,3-trimethylindolenine-ω-aldehyde-N,N-diphenylhydrazone, P-diethylbenzaldehyde -Hydrazones such as 3-methylbenzthiazolinone-2-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-(-diethylaminophenyl)pyrazoline,
1-[pyridyl(3)]-3-(P-diethylaminostyryl)-5-(P-diethylaminophenyl)pyrazoline 1-[lepidyl(2)]-3-(-diethylaminostyryl)-5-(P- diethylaminophenyl)pyrazoline, 1-[pyridyl(2)]-3-(P-
diethylaminostyryl)-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-3-(α-benzyl-p-diethylaminostyryl)-5-(P-diethylaminophenyl)
Pyrazolines such as pyrazoline and spiropyrazoline, 2-(P-diethylaminostyryl)-6-diethylaminobenzoxazole, 2-(P-diethylaminophenyl)-4-(P-dimethylaminophenyl)-5-(2-chlorophenyl) ) Oxazole compounds such as 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, pyrivinylanthracene, polyvinylacridine, poly-9-vinylphenylanthracene, pyrene-formaldehyde resin, ethylcarbazole-formaldehyde resin etc. In addition to these organic charge transport materials, inorganic materials such as selenium, selenium-tellurium, amorphous silicon, and cadmium sulfide can also be used. Further, these charge transport substances can be used alone or in combination of two or more. When the charge transport material does not have film-forming properties,
A film can be formed by selecting an appropriate binder. Resins that can be used as binders are:
For example, insulating resins such as acrylic resin, polyarylate, polyester, polycarbonate, polystyrene, acrylonitrile-styrene copolymer, acrylonitrile-butadiene copolymer, polyvinyl butyral, polyvinyl formal, polysulfone, polyacrylamide, polyamide, chlorinated rubber, or poly-N-vinyl. Organic photoconductive polymers such as carbazole, polyvinylanthracene, polyvinylpyrene and the like may be mentioned. Since the charge transport layer has a limit in its ability to transport charge carriers, it cannot be made thicker than necessary. Generally it is 5 to 30μ, but the preferred range is 8 to 20μ. When forming the charge transport layer by coating, an appropriate coating method as described above can be used. 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. Examples of the substrate having a conductive layer include those whose substrate itself is conductive, such as aluminum, aluminum alloy, copper, zinc, stainless steel, vanadium, molybdenum, chromium, titanium, nickel,
Indium, gold, platinum, etc. can be used,
In addition, plastics having a layer formed by vacuum evaporation of aluminum, aluminum alloy, indium oxide, tin oxide, indium oxide-tin oxide alloy, etc., such as polyethylene, polypropylene, polyvinyl chloride, polyethylene terephthalate, acrylic resin, (polyfluorinated ethylene, etc.), a substrate made of plastic coated with conductive particles (e.g. carbon black, 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. It can be formed by The appropriate thickness of the undercoat layer is 0.1 to 5 microns, preferably 0.5 to 3 microns. When using a photoreceptor in which a conductive layer, a charge generation layer, and a charge transport layer are laminated in this order, and the charge transport material is an electron transport material, the surface of the charge transport layer must be positively charged, and exposure after charging is required. Then, in the exposed area, electrons generated in the charge generation layer are injected into the charge transport layer, and then reach the surface and neutralize the positive charges, causing attenuation of the surface potential and creating an electrostatic contrast with the unexposed area. A visible image is obtained by developing the electrostatic latent image thus formed with a negatively charged toner. This can be directly fixed, or the toner image can be transferred to paper, plastic film, etc. and then developed and fixed. Alternatively, a method may be used in which the electrostatic latent image on the photoreceptor is transferred onto an insulating layer of transfer paper, then developed and fixed. The type of developer, developing method, and fixing method may be any known developer or known method, and are not limited to a specific one. On the other hand, when the charge transport material consists of a hole transport material, the surface of the charge transport layer must be negatively charged.
After charging, when exposed to light, holes generated in the charge generation layer in the exposed area are injected into the charge transport layer, and then reach the surface and neutralize the negative charge, causing a decrease in surface potential and static electricity between the exposed area and the unexposed area. Electrocontrast occurs. During development, it is necessary to use a positively charged toner, contrary to the case where an electron transport material is used. When using a photoreceptor in which a conductive layer, a charge transport layer, and a charge generation layer are laminated in this order, and the charge transport material is made of an electron transport material, the charge generation layer must be negatively charged, and when exposed after being charged, it is exposed to light. In this case, electrons generated in the charge generation layer are injected into the charge transport layer and then reach the substrate. On the other hand, holes generated in the charge generation layer reach the surface and the surface potential is attenuated, creating an electrostatic contrast with the unexposed area. A visible image is obtained by developing the electrostatic latent image thus formed with a positively charged toner. This can be directly fixed, or the toner image can be transferred to paper, plastic film, etc. and then developed and fixed. Alternatively, a method may be used in which the electrostatic latent image on the photoreceptor is transferred onto an insulating layer of transfer paper, then developed and fixed. The type of developer, the developing method, and the fixing method may be any known ones or methods, and are not limited to specific ones. On the other hand, when the charge transport material is a hole transport material, it is necessary to positively charge the surface of the charge generation layer, and when exposed to light after charging, the holes generated in the charge generation layer are injected into the charge transport layer in the exposed area. Then it reaches the substrate. On the other hand, electrons generated in the charge generation layer reach the surface, causing attenuation of the surface potential and creating an electrostatic contrast with the unexposed area. During development, it is necessary to use a negatively charged toner, contrary to the case where an electron transporting substance is used. In another specific example of the present invention, organic photoconductive materials such as the aforementioned hydrazones, pyrazolines, oxazoles, thiazoles, triarylmethanes, polyarylalkanes, triphenylamines, poly-N-vinylcarbazoles, etc. sexual substances and zinc oxide,
The photosensitive coating may contain the metallocene compound described above as a sensitizer for inorganic photoconductive substances such as cadmium sulfide and selenium. This photosensitive film is formed by coating these photoconductive substances and the above-mentioned metallocene compound together with a binder. Another specific example of the present invention is disclosed in Japanese Unexamined Patent Application Publication No. 1986-
It can also be used as a type of photoreceptor in which a charge generating material is added to a charge transfer complex as disclosed in Japanese Patent No. 916483 (photoconductive member). Each of the photoreceptors contains at least one metallocene compound selected from the compounds represented by the general formula (I) of the present invention, and is optionally combined with other photoconductive pigments or dyes having different light absorption properties. By using this, the sensitivity of this photoreceptor can be increased or it can be made into a panchromatic photoreceptor. The electrophotographic photoreceptor of the present invention can be used not only for electrophotographic copying machines, but also for laser printers and CRTs.
It can also be widely used in electrophotographic applications such as printers. The present invention will be explained below using examples. Examples 1 to 15 An ammonia aqueous solution of casein (11.2 g of casein, 1 g of 28% ammonia water, 222 ml of water) was applied onto an aluminum plate using a Mayer bar so that the film thickness after drying was 1.0 μm, and dried. Next, 5 g of the 15 metallocene compounds listed as specific examples were added to a solution of 2 g of butyral resin (degree of butyralization: 63 mol %) dissolved in 95 ml of isopropyl alcohol to prepare 15 types of coating liquids. After each coating solution was dispersed in a sand mill, it was applied onto the casein subbing layer described above using a Mayer bar so that the film thickness after drying was 0.1 μm, and dried to form a charge generation layer. Then, P-diethylaminobenzaldehyde-N-α-naphthyl-N-phenylhydrazone was added.
5g and polymethyl methacrylate (number average molecular weight
100,000) was dissolved in 70 ml of benzene, and this was applied onto the charge generation layer using a Mayer bar so that the film thickness after drying was 12μ, and dried to form a charge transport layer. The 15 types of electrophotographic photoreceptors created in this way were tested using an electrostatic copying paper tester Model SP- manufactured by Kawaguchi Electric Co., Ltd.
428 using the dynamic method at -5KV, held in a dark place for 1 second, and then charged at 4KV with an illuminance of 5lux.
It was exposed to light for a second and the charging characteristics were examined. The charging characteristics are the initial charging potential (Vo) and 1
The amount of exposure (E1/2) required to attenuate the potential to 1/2 when dark decaying for a second was measured. Also 20lux,
The residual potential after sec exposure was expressed as _VR . The results are shown in Table 1.

【table】

【table】

[Table] Comparative examples 1 to 5 A photoreceptor was prepared in the same manner as in Example 1 except that the metallocene compound of Example 1 was used as the comparative compound, and the characteristics were investigated. The results are shown in Table 2.

[Table] All of the comparative examples have lower sensitivity and larger residual potential than the examples of the present invention. Furthermore, using the charge measuring device used in Example 1,
The same charging and exposing operation as in Example 1 was repeated 5000 times using a dynamic method, and the changes in the initial charging potential Vo and the residual potential _VR after exposure were investigated and are shown in Table 3. Note that the same measurements were performed on the photoreceptors of Examples 3, 9, and 11.

[Table] Although the photoreceptors of the comparative examples all have high initial residual potentials, the residual potentials during repeated use are extremely high, and this pushes up the V _p as well, which is a major problem due to lack of stability in practical use. On the contrary, it is clear that the examples of the present invention are extremely stable even after repeated use and have excellent properties in practical use. Examples 16 to 18 A casein subbing layer was coated on an aluminum plate in the same manner as in Example 1. Next, a charge transport layer containing the hydrazone compound used in Example 1 as a charge transport substance had a film thickness of 12 μm after drying.
It was coated with a Mayer bar to give the following properties and dried to form a charge transport layer. Next, the three coating solutions of Examples 3, 9, and 11 were applied onto the charge transport layer using a Mayer bar so that the film thickness after drying was 0.1 μm, and dried to form a charge generation layer. The charging characteristics of the three types of electrophotographic photoreceptors thus prepared were examined in the same manner as in Example 1.
This +5KV caused a corona charge. This result is the fourth
Shown in the table.

[Table] Example 19 1 g of poly-N-vinylcarbazole and 5 g of the above-mentioned exemplified metallocene compound No. 3 were added to 10 g of 1,2-dichloroethane, and then thoroughly stirred. The coating solution thus prepared was applied onto a polyethylene terephthalate film on which aluminum was vapor-deposited using a doctor blade so that the dry film thickness was 15 μm. The charging characteristics of this photoreceptor were measured in the same manner as in Example 1. However, the charging polarity was set to be positive. As a result, V _p is +585, and E1/2 is 3.1lux, sec
It was hot. Example 20 A photoreceptor was prepared in exactly the same manner as in Example 19, except that the exemplified metallocene compound No. 9 was used in place of the exemplified metallocene compound No. 3 used in the preparation of the electrophotographic photoreceptor in Example 19. After that, the charging characteristics of this photoreceptor were measured. However, the charging polarity was set as positive. This result shows that V _p is +570V, E1/2 is 3.1lux,
It was hot in sec. Example 21 10 g of fine particle zinc oxide (Sazex2000 manufactured by Sakai Chemical Co., Ltd.),
Acrylic resin (Dyanal manufactured by Mitsubishi Rayon Co., Ltd.)
4g of LR009), 10g of toluene, and 10mg of the above-mentioned exemplified metallocene compound No. 8 were thoroughly mixed in a ball mill, and the resulting coating solution was applied to a polyethylene terephthalate film coated with aluminum using a doctor blade to a dry film thickness of 21μ. An electrophotographic photoreceptor was prepared by coating the film and drying it. When the spectral sensitivity of this electrophotographic photoreceptor was measured using spectrophotography using electrophotography, it was found that the photoreceptor of this example was more sensitive on the long wavelength side than the zinc oxide coating that did not contain the metallocene compound mentioned above. It was found that it has. Example 22 An ammonia aqueous solution of casein was coated on an aluminum plate with a thickness of 100 μm and dried to form a subbing layer with a thickness of 1.1 μm. Next, 5 g of 2,4,7-trinitro-9-fluorenone and 5 g of poly-N-vinylcarbazole (number average molecular weight: 300,000) were dissolved in 70 ml of tetrahydrofuran to form a charge transfer complex compound. This charge transfer complex compound and the above-mentioned exemplified metallocene compound No. 15
1g of polyester (Byron, manufactured by Toyobo Co., Ltd.)
It was added to a solution in which 5 g was dissolved in 70 ml of tetrahydrofuran and dispersed. This dispersion was applied onto the undercoat layer so that the film thickness after drying was 12μ, and dried. The charging characteristics of the photoreceptor thus prepared were measured in the same manner as in Example 1. However, the charging polarity was set to be positive. This result shows that V _p is +560V, E1/2 is 5.0lux,
It showed sec. Example 23 A polyvinyl alcohol film having a thickness of 1.1 μm was formed on the aluminum surface of an aluminum vapor-deposited polyethylene terephthalate film. Next, the above-mentioned dispersion of metallocene compound No. 4 used in Example 4 was placed on the polyvinyl alcohol layer formed earlier so that the film thickness after drying was
It was coated with a Mayer bar to a thickness of 0.5μ and dried to form a charge generation layer. Next, 5 g of 1-[pyridyl(2)]-3-(P-diethylaminostyryl)-5-(P-diethylaminophenyl)pyrazoline and polyarylate (condensation polymer of bisphenol A and terephthalic acid-isophthalic acid) A solution obtained by dissolving 5 g in 70 ml of tetrahydrofuran was applied onto the charge generation layer so that the film thickness after drying was 10 μm, and dried to form a charge transport layer. The charging characteristics of the electrophotographic photoreceptor thus prepared were measured in the same manner as in Example 1. The results were as follows. V _p : -605V, E1/2: 3.4lux, sec Effects of the Invention As is clear from the above, the present invention has high sensitivity and good repeatability by using the specific metallocene compound. It was possible to obtain an electrophotographic photoreceptor that can be used even in charging mode.

Claims (1)

[Scope of Claims] 1. An electrophotographic photoreceptor having a conductive substrate and a photoconductive layer, wherein the photoconductive layer has the general formula However, in the formula, m is an integer of 0.1 or 2, A represents a sulfur atom or an oxygen atom, and B represents a benzothirium ring, a benzoxothiylium ring, a naphthothiylium ring, or a naphthothiylium ring which may have a substituent. Indicates the residues necessary to form a ring,
An electrophotographic photoreceptor comprising a metallocene compound, wherein M represents a metal element selected from Ti, V, Cr, Fe, Co, Ni, and Rn, and X ^- represents an anionic functional group.