JPH0324662B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an electrophotographic photoreceptor, and more particularly to an electrophotographic photoreceptor having a photosensitive layer containing a novel organic photoconductive substance comprising a triazole compound. Conventionally, inorganic photoconductive materials such as selenium, cadmium sulfide, and zinc oxide are known as photoconductive materials used in electrophotographic photoreceptors. These photoconductive materials have a number of advantages, such as being able to be charged to an appropriate potential in the dark, having little charge dissipation in the dark, or quickly dissipating the charge when irradiated with light. However, it also has various drawbacks. For example, selenium-based photoreceptors easily crystallize due to factors such as temperature, humidity, dust, and pressure. Especially when the ambient temperature exceeds 40°C, crystallization becomes significant, resulting in decreased charging performance and white spots on images. There is a drawback when this occurs. Furthermore, selenium-based photoreceptors and cadmium sulfide-based photoreceptors have the disadvantage that stable sensitivity and durability cannot be obtained when used under high humidity over time. In addition, zinc oxide photoreceptors require the sensitizing effect of sensitizing photodyes such as rose bengal, but such sensitizing dyes cause charging deterioration due to corona charging and photobleaching due to exposure light, so long-term sensitizing effects are required. It has the disadvantage that it cannot provide a stable image over a long period of time. On the other hand, various organic photoconductive polymers including polyvinylcarbazole have been proposed, but these polymers are superior in terms of film formability and lightness compared to the inorganic photoconductive materials mentioned above. However, it has been difficult to put them into practical use to date because sufficient film-forming properties have not yet been achieved, and inorganic photoconductive materials lack sensitivity, durability, and stability against environmental changes. This was because it was inferior compared to. In addition, triarylpyrazoline compounds described in U.S. Pat. No. 3,837,851, etc.,
9-styrylanthracene compounds described in JP-A No. 94828, JP-A-51-94829, etc.
Low molecular weight organic photoconductive materials such as the 4-chlorooxazole compound described in Japanese Patent No. 53278 have been proposed. Such low-molecular organic photoconductive materials are
By appropriately selecting the binder to be used, it has become possible to overcome the drawbacks of film-forming properties that had been a problem in the field of organic photoconductive polymers, but it is still insufficient in terms of sensitivity. do not have. An object of the present invention is to provide a new electrophotographic photoreceptor that eliminates the above-mentioned drawbacks or disadvantages. Another object of the invention is to provide new organic photoconductive materials. Another object of the present invention is to provide a compound suitable as a charge transport substance for use in a photosensitive layer having a laminated structure of a charge generation layer and a charge transport layer. This object of the present invention is achieved by an electrophotographic photoreceptor having a photosensitive layer containing a compound represented by the following general formula (1). General formula (1) In the formula, R ₁ is an aryl group (e.g., phenyl group,
naphthyl group, anthryl group) or heterocyclic group (e.g. pyridine, quinoline, carbazole,
A monovalent heterocyclic group derived from phenothiazine, phenoxazine, etc. The above-mentioned aryl group and heterocyclic group can have a substituent or an atom. Aryl groups include di-substituted amino groups (e.g., dimethylamino, diethylamino,
dipropylamino group, dibutylamino group, dibenzylamino group, diphenylamino group, ditolylamino group, dixylylamino group, etc.), cyclic amino group (for example, morpholino group, pyrrolidino group, piperidino group, etc.) or alkoxy group (methoxy group, ethoxy group, propoxy group, putoxy group, etc.) is preferable. In addition, aryl groups and heterocyclic groups include alkyl groups (e.g., methyl, ethyl, propyl,
iso-propyl group, butyl group, t-butyl group, amyl group, t-amyl group, etc.), or a halogen atom (for example, chlorine atom, bromine atom, iodine atom, etc.). R ₂ represents an atomic group necessary to form an aromatic hydrocarbon ring such as a benzene ring, a naphthalene ring, or anthracene ring. These aromatic hydrocarbon rings include, for example, alkyl groups (e.g., methyl group, ethyl group, propyl group, butyl group, amyl group, iso-propyl group, t-butyl group,
t-amyl group, 2-ethylhexyl group, etc.), alkoxy groups (e.g., methoxy group, ethoxy group,
propoxy group, butoxy group), di-substituted amino group (dimethylamino group, diethylamino group, dipropylamino group, dibutylamino group, dibenzylamino group, diphenylamino group, ditolylamino group, etc.), cyclic amino group (e.g. morpholino group), group, pyrrolidino group, piperidino group, etc.), or a halogen atom (eg, chlorine atom, bromine atom, iodine atom, etc.). Representative examples of the compound represented by the general formula (1) used in the present invention are listed below. These triazole compounds have the following general formula:
It can be easily obtained by oxidizing and ring-closing the compound represented by (2) using a conventional method. General formula (2) (In the formula, R ₁ and R ₂ are synonymous with the above.) Next, the triazole compound used in the present invention will be specifically explained using a synthesis example. Synthesis example (Synthesis of the above triazole compound T-1) 200
ml three-neck flask In the general formula (2), R ₁ is P-
8.00 g of dimethylaminophenyl group, a compound in which R ₂ is an atom group forming a benzene ring (3.33/100
mol) and 40 g of pyridine were added and dissolved. On the other hand, 10 g of copper sulfate was dissolved in 20 g of water, and this solution was added to the pyridine solution. Next, heat to 80℃ and while stirring.
I blew air into it for 10 hours. After cooling, the precipitate was separated, washed twice with water, and recrystallized with methyl ethyl ketone to give mp.177.5-178.5 yellow crystals, 2.89 g (yield 36%).
I got it. Elemental analysis Molecular formula C ₁₄ H ₁₄ N ₄ Calculated value Analytical value C 70.55% 70.53% H 5.93% 5.95% N 23.51% 23.52% Other triazole compounds used in the present invention can be synthesized in the same manner. The electrophotographic photoreceptor containing the triazole compound represented by the general formula (1) can be applied to any type of electrophotographic photoreceptor using an organic photoconductive substance, but the preferred type is 1. Electron-donating substance A charge transfer complex is formed by a combination of and an electron-accepting substance. 2 Organic photoconductor sensitized by adding dye. 3 Pigment dispersed in a hole matrix. 4 Functionally separated into charge generation layer and charge transport layer. 5. Those whose main components are a eutectic complex consisting of a dye and a resin and an organic photoconductor. 6 A charge transfer complex containing an organic or inorganic charge generating material. Among them, types 3) to 6) are desirable. Furthermore, in the case of a 4) type photoreceptor, that is, a triazole compound represented by general formula (1) is used as a charge transport material for the charge transport layer of a photoreceptor that is functionally separated into two layers: a charge generation layer and a charge transport layer. When used, the sensitivity of the photoreceptor is particularly improved and the residual potential is low. Further, in this case, a decrease in sensitivity and an increase in residual potential during repeated use can be suppressed to a practically negligible level. Therefore, the 4) type of photoreceptor will be described in detail. The layer structure requires a conductive layer, a charge generation layer, and a charge transport layer, and the charge generation layer may be placed either above or below the charge transport layer, but in an electrophotographic photoreceptor of the type that is used repeatedly, Mainly from the viewpoint of physical strength, and in some cases from the viewpoint of chargeability, it is preferable to laminate a conductive layer, a charge generation layer, and a charge transport layer in this order. An adhesive layer may be provided as necessary for the purpose of improving the adhesiveness between the conductive layer and the charge generation layer. The charge transport layer used in the present invention is preferably formed by applying a solution prepared by dissolving the triazole compound represented by the general formula (1) and a binder in an appropriate solvent and drying the solution. Examples of the binder used here include polysulfone, acrylic resin, methacrylic resin, vinyl chloride resin,
Examples include vinyl acetate resins, phenolic resins, epoxy resins, polyester resins, alkyd resins, polycarbonates, polyurethanes, and copolymer resins containing two or more repeating units of these resins, particularly polyester resins,
Polycarbonate is preferred. poly
Photoconductive polymers which themselves have charge transport capabilities, such as N-vinylcarpazole, can also be used as binders. The blending ratio of this binder and charge transport compound is
Preferably, the charge transport compound is contained in an amount of 10 to 500 parts by weight per 100 parts by weight of the binder. The thickness of this charge transport layer is between 2 and 100 microns, preferably between 5 and 30 microns. Further, as the coating method used when providing the charge transport layer, conventional methods such as blade coating method, Mayer bar coating method, spray coating method, dip coating method, bead coating method, air knife coating method, curtain coating method, etc. are used. be able to. Further, the solvent used in forming the charge transport layer of the present invention includes many useful organic solvents. Typical examples include aromatic hydrocarbons such as benzene, naphthalene, toluene, xylene, mesitylene, and chlorobenzene;
Ketones such as acetone and 2-butanone, halogenated aliphatic hydrocarbons such as methylene chloride, chloroform, and ethylene chloride, cyclic or linear ethers such as tetrahydrofuran and ethyl ether, or mixed solvents thereof. can be mentioned. The charge transport layer of the present invention can contain various additives. Such additives include diphenyl, diphenyl chloride, O-terphenyl,
P-terphenyl, dibutyl phthalate, dimethyl glycol phthalate, dioctyl phthalate, triphenyl phosphoric acid, methylnaphthalene, benzophenone, chlorinated paraffin, dilaurylthiopropionate, 3,5-dinitrosalicylic acid,
Various fluorocarbons, silicone oil, silicone rubber or dibutylhydroxytoluene,
2,2'-methylene-bis-(6-t-butyl-4
-methylphenol), α-tocopherol, 2
-t-octyl-5-chlorohydroquinone,
Examples include phenolic compounds such as 2,5-di-t-octylhydroquinone. As the charge generation material used in the charge generation layer, any material can be used as long as it absorbs light and generates charge carriers with extremely high efficiency. Preferred materials include selenium, selenium, etc.
Inorganic substances such as tellurium, selenium/arsenic, cadmium sulfide, amorphous silicon, pyrylium dyes, thiopyrylium dyes, triarylmethane dyes, thiazine dyes, cyanine dyes, phthalocyanine pigments, perylene pigments, indigo pigments , thioindigo pigments, quinacridone pigments, squaric acid pigments, azo pigments, and polycyclic quinone pigments. The thickness of the charge generation layer is preferably 5μ or less, preferably 0.05 to 3μ. Representative examples of charge generating substances that can be used in the present invention are shown below. Charge generating substances (1) Amorphous silicon (2) Selenium-tellurium (3) Selenium-arsenic cadmium sulfide These pigments can be used alone or in combination of two or more. Further, the crystal form of these pigments may be α type, β type or any other type, but β type is particularly preferred. In the present invention, when forming a charge generation layer using the above-mentioned compound, the above-mentioned compound is applied by vacuum evaporation, sputtering, glow discharge, etc.
A layer of the compound can be formed. Also,
A layer can be formed by dispersing the aforementioned compound in a suitable binder and applying this dispersion by a suitable coating method. In addition, when dispersing the above-mentioned compound in a binder-free manner, it can be dispersed by a known method using a ball mill, an attritor, etc., and the particle size is 5 microns or less, preferably 2 microns or less, and optimally 0.5 microns. The following is desirable. In addition, the aforementioned compounds were added to ethylenediamine, diethylenetriamine, tetraethylenepentamine, pentaethylenehexamine, diethylaminopropylamine, N-aminoethylpiperazine, benzyldimethylamine, α
- It can also be applied by dissolving it in an amine solvent such as methylpenzyldimethylamine or tridimethylaminomethylphenol. As a coating method, conventional methods such as a blade coating method, a Meyer bar coating method, a spray coating method, a dip coating method, a bead coating method, an air knife coating method, and a curtain coating method can be used. The thickness of the charge generation layer used in the present invention is suitably 5 microns or less, preferably 0.01 micron to 1 micron. Binders for dispersing the aforementioned compounds include polyvinyl butyral, polymethyl methacrylate, polyester, polyvinylidene chloride, polyamide, chlorinated rubber, polyvinyltoluene, polystyrene, polyvinyl chloride, ethyl cellulose,
Examples include polyvinylpyridine, styrene-maleic anhydride copolymer, and the like. The proportion of such a binder in the charge generation layer is preferably 80% by weight or less, preferably 50% by weight or less of the total weight of the charge generation layer. Furthermore, in the electrophotographic photoreceptor of the present invention, in order to uniformly inject carriers into the charge transport layer above the charge generation layer, the surface of the charge generation layer can be polished to a mirror finish, if necessary. . As the mirror finishing method, for example, the method disclosed in Japanese Patent Application Laid-Open No. 155356/1983 can be used. The conductive layer may be any type of conductive layer conventionally used as long as it is imparted with conductivity. As the material for the adhesive layer, various conventionally used binders such as casein, polyvinyl alcohol, nitrocellulose, hydroxypropylmethylcellulose, and polyamide can be used. The appropriate thickness of the adhesive layer is 0.1-5μ, preferably 0.5-3μ. The triazole compound used in the present invention has hole transport properties, and when using a photoreceptor in which a conductive layer, a charge generation layer, and a charge transport layer are laminated in this order, the surface of the charge transport layer must be negatively charged. When exposed to light, holes generated in the charge generation layer are injected into the charge transport layer in the exposed area, and then reach the surface and neutralize the negative charge, causing a decrease in surface potential and creating an electrostatic contrast between the exposed area and the unexposed area. occurs. Various conventionally used developing methods can be used for visualization. Regarding photoreceptors other than the (4) type, implementation modes are described in numerous patent publications and documents that have been proposed so far, so the description is omitted here, but the present invention applies to these types of photoreceptors as well. These triazole compounds are effective. The electrophotographic photoreceptor of the present invention can be used not only in electrophotographic copying machines but also in a wide range of electrophotographic application fields such as laser printers, CRT printers, and electrophotographic plate making systems. Next, examples of the present invention will be shown. Example 1 Ammonia aqueous solution of casein (11.2 g of casein, 1 g of 28% ammonia water, 222 ml of water) on an aluminum plate.
Coated with Meyer bar and dried, coating amount 1.1g/m ²
An adhesive layer was formed. Next, 5 g of a disazo pigment having the following structure and Butyral resin (degree of butyralization 63 mol%) 2g
After dispersing it with a solution dissolved in 95 ml of ethanol, it was coated on the adhesive layer and the coating amount after drying was 0.2 g/
A charge generation layer of m ² was formed. Next, the triazole compound (T-1) 5
g, poly-4,4'-dioxydiphenyl-2,
2′-propane carbonate (viscosity average molecular weight
30000) dissolved in 150 ml of dichloromethane is applied onto the charge generation layer and dried to give a coating amount of 10 g/m ²
A charge transport layer was formed. The electrophotographic photoreceptor thus prepared was statically charged with corona at 5 KV using an electrostatic copying paper testing device Model SP-428 manufactured by Kawaguchi Electric Co., Ltd.
After holding it in a dark place for 10 seconds, it was exposed to light at an illuminance of 5 lux to examine the charging characteristics. Initial potential Vo (V), potential retention rate for 10 seconds in the dark Rv (%), half-attenuation exposure amount E1/2 (lux.sec)
The charging characteristics of this photoreceptor are shown below. Vo: 550V Rv: 91% E1/2: 10.8lux.sec Examples 2 to 10 The following pigments were vacuum deposited on an aluminum plate with a thickness of 100μ to form a charge generation layer with a thickness of 0.15μ. Next, a solution prepared by dissolving 5 g of polyester resin (Pylon 200, Toyobo Co., Ltd.) and 5 g of the above-mentioned exemplified triazole compound shown in Table 1 in 150 ml of dichloromethane was applied onto the charge generation layer and dried, resulting in a coating amount of 11
A charge transport layer of g/m ² was formed. The charging characteristics of the electrophotographic photoreceptor thus prepared were examined in the same manner as in Example 1, and the results are shown in Table 1.
It was shown to.

[Table] Example 12 Selenium/tellurium (10% tellurium) was vacuum deposited on an aluminum plate to form a charge generation layer with a thickness of 0.8 μm. Next, the same charge transport layer as used in Example 1 was coated and dried to give a coating weight of 11 g/m ² . The charging characteristics of the electrophotographic photoreceptor thus prepared were examined in the same manner as in Example 1, and the results are shown below. Vo: 610V Rv: 89% E1/2: 6.3lux.sec Example 13 Triazole compound (T-
1) 1.0 g of β-type copper phthalocyanine was added to a solution of 5 g of poly-N-vinylcarbazole (molecular weight: 300,000) dissolved in 150 ml of dichloromethane, and after dispersion, the aluminum plate with the casein layer used in Example 1 was prepared. on top of the casein layer and adjust the coating amount after drying.
It was set to 10g/ ^m2 . Charge measurement of the photoreceptor thus prepared was carried out in the same manner as in Example 1, and the results are shown below.
However, the charging polarity was determined. Vo: 480V Rv: 86% E1/2: 19.4lux.sec Example 14 A 0.2 mm thick molybdenum plate (substrate) whose surface was cleaned was fixed at a predetermined position in a glow discharge deposition tank. Next, the inside of the tank was evacuated to a vacuum level of approximately 5×10 ^-6 torr. After that, the input voltage of the heater was increased to stabilize the molybdenum substrate temperature at 150℃. After that, hydrogen gas and silane gas (15% by volume relative to hydrogen gas) were introduced into the tank and stabilized at 0.5 torr by adjusting the gas flow rate and the main valve of the deposition tank. Next, 5MHz high-frequency power was applied to the induction coil to generate glow discharge inside the coil in the tank, resulting in an input power of 30W. An amorphous silicon film was grown on the substrate under the above conditions, and the same conditions were maintained until the film thickness reached 2 μm, after which glow discharge was discontinued. Then the heating heater,
Turn off the high frequency power supply, wait for the substrate temperature to reach 100℃, close the hydrogen gas and silane gas outflow valves, and once the temperature inside the tank is below 10 ^-5 torr,
The pressure was returned to atmospheric pressure and the board was taken out. Next, a charge transport layer was formed on this amorphous silicon layer in exactly the same manner as in Example 1. The photoreceptor thus obtained was placed in a charging and exposure experimental device, charged with corona at 6 KV, and immediately irradiated with a light image. The light image was illuminated through a transmission test chart using a tungsten lamp light source. Thereafter, a good toner image was obtained on the photoreceptor surface by immediately cascading a charged developer (including toner and carrier) onto the photoreceptor surface.

Claims (1)

[Scope of Claims] 1. An electrophotographic photoreceptor comprising a photosensitive layer containing a compound represented by the following general formula (1). General formula (1) (In the formula, R ₁ represents a substituted or unsubstituted aryl group or a substituted or unsubstituted heterocyclic group.
R ₂ represents an atomic group necessary to form a substituted or unsubstituted aromatic hydrocarbon ring. )