JPH0473782B2 - - 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 hydrazone 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 dyes such as rose bengal, but such sensitizing dyes cause charge deterioration due to corona charging and photobleaching due to exposure light, so it may take a long time. 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 to the aforementioned inorganic photoconductive materials in terms of film formability and light weight. However, it has been difficult to put them into practical use to date because they have not yet achieved sufficient film-forming properties, and they are inferior to inorganic photoconducting materials in terms of sensitivity, durability, and stability against environmental changes. It was because it was hot. In addition, triarylpyrazoline compounds described in U.S. Patent No. 3837851, etc., and U.S. Patent No. 4150987
The hydrazone compound described in the publication No. 51-
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 material for use in a photosensitive layer having a laminated structure of a charge generation layer and a charge transport layer. Such an object of the present invention is to satisfy the following general formula (1) or (2).
This is achieved by an electrophotographic photoreceptor having a layer containing a hydrazone compound represented by: general formula In the formula, R ₁ and R ₂ represent a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted aralkyl group, and X, together with the carbon atom and Y in the formula, represents a 4-membered ring, 5 Indicates a divalent group necessary to form a 4-membered ring and a 6-membered ring, and Y represents a divalent group necessary to form a 4-membered ring, a 5-membered ring, and a 6-membered ring together with the carbon atom and represents a group of 4 and Z together with the carbon atom in the formula.
Indicates a divalent group necessary to form a membered ring, a 5-membered ring, and a 6-membered ring. Furthermore, R, X, Y, and Z in this formula will be explained. In the formula, R ₁ and R ₂ are substituted or unsubstituted alkyl groups (e.g., methyl group, ethyl group, n-propyl group, iso-propyl group, n-butyl group, sec-
Butyl group, t-butyl group, n-amyl group, t-amyl group, n-octyl group, 2-ethylhexyl group, t-octyl group, 2-hydroxyethyl group,
3-hydroxypropyl group, 2-chloroethyl group, 3-chloropropyl group, 2-methoxyethyl group, 3-methoxypropyl group, etc.), substituted or unsubstituted aralkyl group (e.g. benzyl group,
phenethyl group, chlorobenzyl group, dichlorobenzyl group, methoxybenzyl group, α-naphthylmethyl group, β-naphthylmethyl group), substituted or unsubstituted aryl group (e.g. phenyl group, tolyl group, xylyl group, diphenyl group) , chlorophenyl group, dichlorophenyl group, trichlorophenyl group, methoxyphenyl group, dimethoxyphenyl group, cyanophenyl group, α-naphthyl group, β-naphthyl group, etc.). Specific examples of the 4-membered ring, 5-membered ring, and 6-membered ring containing X, Y, and Z in the formula include the following structural formulas.

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[Formula] The hydrogen atom in the above structural formula is an alkyl group such as a methyl group, an ethyl group, a propyl group, a butyl group, an acyl group, an octyl group, a halogen atom such as a chlorine atom, a bromine atom, an iodine atom, a methoxy group, Alkoxy groups such as ethoxy, propoxy, and butoxy groups, substituted amino groups such as dimethylamino, diethylamino, dipropylamino, dibutylamino, dibenzylamino, and diphenylamino groups, acetylamino, propionylamino, and butyrylamino It can also be substituted with a group, an acylamino group such as a benzoylamino group or a trioylamino group, a hydroxy group, or the like. Specific examples of the hydrazone compound represented by the general formula (1) or (2) are listed below. These hydrazone compounds represented by formula (1) or (2) can be produced by known methods. For example, general formula and (wherein X, Y and Z have the same meanings as above) and the general formula (In the formula, R ₁ and R ₂ have the same meanings as above)
It can be synthesized by a conventional method using a hydrazine compound represented by Next, the synthesis method for typical examples of hydrazone compounds used in the present invention will be shown below. Synthesis example (synthesis of the hydrazone compound H-1)
General formula (3) consists of the following structural formula 6.49g (0.03mol) of diketone and general formula (5) where R ₁ is phenyl group and R ₂ is α-
16.40g of hydrazine compound consisting of naphthyl group
(0.07 mol), 100 ml of ethanol, and 100 ml of acetic acid were mixed and stirred for 3 hours to react. After the reaction, this solution was poured into water, and the resulting precipitate was separated and dried. This solid content is recrystallized with alcohol and has a melting point of 194.
7.79 g of crystals (yield: 40%) were obtained at -197°C. Elemental analysis Composition formula C ₄₆ H ₄₀ N ₄ = 648.90 Calculated value Analyzed value C 85.13% 85.20% H 6.23% 6.20% N 8.64% 8.60% Other hydrazone compounds used in the present invention can be synthesized in the same manner. . The electrophotographic photoreceptor containing the hydrazone compound represented by the general formula (1) or (2) can be applied to any type of electrophotographic photoreceptor using an organic photoconductive substance, but the preferred type is 1. A charge transfer complex formed by a combination of an electron-donating substance and an electron-accepting substance. 2 Organic photoconductor sensitized by adding dye. 3 A 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. etc., among which types 3 to 6 are desirable. Furthermore, in the case of four types of photoreceptors, that is, the charge transport material used in the charge transport layer of a photoreceptor that is functionally separated into two layers, a charge generation layer and a charge transport layer, is represented by general formula (1) or (2). When a hydrazone compound is 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 four types of photoreceptors 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 either above or below the charge transport layer, but in electrophotographic photoreceptors of the type that are used repeatedly, it is mainly From the viewpoint of physical strength and, in some cases, 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 can be formed by applying a solution in which a hydrazone compound represented by the general formula (1) or (2) and a binder are dissolved in an appropriate solvent and drying the solution. is preferred.
Examples of the binder used here include polysulfone, acrylic resin, methacrylic resin, vinyl chloride resin, vinyl acetate resin, phenol resin, epoxy resin, polyester resin, alkyd resin, polycarbonate, polyurethane, or repeating units of these resins. Examples include copolymer resins containing two or more of them, with polyester resins and polycarbonates being particularly preferred.
Additionally, photoconductive polymers that themselves have charge transport capabilities, such as poly-N-vinylcarbazole, 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-tocophenol, 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/tellurium, Inorganic substances such as selenium, arsenic cadmium sulfide, amorphous silicon, pyrylium dyes, thiopyrylium dyes, triarylmethane dyes, thiazine dyes, cyanine dyes, phthalocyanine pigments, berylene pigments, isidigo pigments, and thioindigo dyes. Pigments, quinacridone pigments,
Examples include organic substances such as 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 (4) Cadmium sulfide

【formula】

(62) Methyl squarate dye (63) Indigo dye (C, 1, No. 78000) (64) Thioindigo dye (C, 1, No. 78800) (65) Copper phthalocyanine These pigments may be one or two types. More than one species can be used in combination. Further, the crystal type of these pigments may be α, β or any other type, but the β type is particularly preferred. In the present invention, when forming a charge generation layer using the above-mentioned pigment, the pigment layer can be formed by vacuum evaporation, sputtering, glow discharge, etc. of the above-mentioned pigment. Alternatively, a layer can be formed by dispersing the above-mentioned pigment in a suitable binder and applying this dispersion using a suitable coating method. In addition, the above-mentioned pigment layer can also be formed in a binder-free manner. When dispersing the above-mentioned pigment, it can be dispersed by a known method using a pole mill, an attritor, etc., and it is desirable that the particle size is 5 microns or less, preferably 2 microns or less, and optimally 0.5 microns or less. In addition, the above-mentioned pigments can be added to ethylenediamine, diethylenetriamine, tetraethylenepentamine, pentaethylenehexamine, diethylaminopropylamine, N-aminoethylpiperazine,
It can also be applied by dissolving it in an amine solvent such as penzyldimethylamine, α-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. 155356/1984 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, hydroxymethyl cellulose, and polyamide can be used. The thickness of the adhesive layer is 0.1-5μ, preferably 0.5-3μ
is appropriate. The hydrazone 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 charged and 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 to neutralize the negative charge, resulting in attenuation of the surface potential and an electrostatic contrast between the exposed area and the unexposed area. occurs. Various conventionally used developing methods can be used for visualization. Regarding photoconductors other than the (4) type, implementation modes are described in numerous patent publications and documents that have been proposed so far, so a detailed explanation will be omitted here. The hydrazone compounds of the present invention 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 applications such as laser printers, CRT printers, and electrophotographic plate making systems. Next, examples of the present invention will be shown. Example 1 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 and dried to form an adhesive layer with a coating weight of 1.0 g/m ² . Next, 5 g of a disazo pigment having the following structure and 2 g of butyral resin (butyralization degree 63 mol%) were dispersed together with a solution dissolved in 95 ml of ethanol, and the coating amount after drying was coated on the adhesive layer to be 0.2 g/ A charge generation layer of m ² was formed. Next, a solution prepared by dissolving 5 g of the hydrazone compound (H-1) and 5 g of poly-4,4'-dioxydiphenyl-2,2-propane carbonate (viscosity average molecular weight 30,000) in 150 ml of dichloromethane was placed on the charge generation layer. The coating was applied and dried to form a charge transport layer with a coating weight of 10 g/m ² . The electrophotographic photoreceptor thus prepared was statically charged with corona at 5 kV using an electrostatic copying tester Model SP-428 manufactured by Kawaguchi Electric Co., Ltd., and after being held in a dark place for 10 seconds, the photoreceptor was charged with an illuminance of 5 lux. It was exposed to light and its charging characteristics were investigated. Initial potential V ₀ (V), potential retention rate for 10 seconds in the dark R _V (%), half-decay exposure amount E1/2 (lux-sec)
The charging characteristics of this photoreceptor are shown below. V ₀ : 550 (V) R _V : 94 (%) E _1/2 : 6.8 (lux・sec) Examples 2 to 18 The following pigments are vacuum deposited on a 100 μ thick aluminum plate and a charge is applied to a thickness of 0.15 μ. A generation layer was formed. Next, 5 g of polyester resin (Vylon 200, Toyobo Co., Ltd.) and the above-mentioned hydrazone compound H-2
~ A solution of 5 g of H-18 dissolved in 150 ml of dichloromethane was applied onto the charge generation layer and dried, resulting in a coating amount of 11 g/
A charge transport layer of m ² was formed. Example 19 An electrophotographic photoreceptor was prepared in the same manner as in Examples 2 to 18 except that 2.5 g of H-1 and 2.5 g of H-12 were used as the exemplary hydrazone compounds. 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 20 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 photosensitive plate thus prepared were examined in the same manner as in Example 1, and the results are shown below. V ₀ : 550V R _V : 90 (%) E _1/2 : 7.0lux・sec Example 21 The hydrazone compound (H-
1) Add 1.0 g of β-type copper phthalocyanine to a solution of 5 g of poly-N-vinylcarbazole (molecular weight: 300,000) dissolved in 150 ml of dichloromethane, and then disperse the aluminum plate with the casein layer used in Example 1. Apply on top of the casein layer and apply 10g/after drying.
^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. V ₀ : 530V R _V : 79% E _1/2 : 9.0lux·sec Example 22 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 a 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. After that, turn off the heater and high frequency power supply, and the board temperature will rise.
After waiting for the temperature to reach 100°C, the hydrogen gas and silane gas outflow valves were closed, and after the inside of the tank was once lowered to below 10 ^-5 torr, the pressure was returned to atmospheric pressure and the substrate was taken out. Next, a charge transport layer was formed on this amorphous silicon layer in 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 layer containing a hydrazone compound represented by the following general formula (1) or (2). (In the formula, R ₁ and R ₂ are substituted or unsubstituted alkyl groups, substituted or unsubstituted aryl groups,
represents a substituted or unsubstituted aralkyl group; Indicates a divalent group necessary to form a 4-membered ring, a 5-membered ring, and a 6-membered ring together with a carbon atom and X, and Z together with a carbon atom in the formula
Indicates a divalent group necessary to form a membered ring, a 5-membered ring, and a 6-membered ring. )