JPS6310417B2 - - 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 consisting of a hydrazone compound. Conventionally, inorganic photoconductive materials such as selenium, cadmium sulfide, and zinc oxide have been 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 images. It has the disadvantage of causing spots. Furthermore, selenium-based photoreceptors and cadmium sulfide-based photoreceptors have the disadvantage that stable sensitivity and durability cannot be obtained when used over time under high humidity. In addition, zinc oxide photoreceptors require the sensitizing effect of sensitizing dyes such as rose bengal, but these sensitizing dyes cause charging deterioration due to corona charging and photobleaching due to exposure, so they cannot be used for a long period of 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 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, hydrazone compounds disclosed in U.S. Pat. No. 4,150,987, triarylpyrazoline compounds described in U.S. Pat. Low-molecular organic photoconductive materials have been proposed, such as the 9-styrylanthracene compound described above and the 4-chlorooxole compound described in JP-A-55-53278. By appropriately selecting the binder used, these low-molecular-weight organic photoconductive materials can overcome the film-forming problems that had been a problem in the field of organic photoconductive polymers. However, it cannot be said to be sufficient in terms of sensitivity. 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 layer containing a hydrazone compound represented by the following general formula (1). General formula (1) In the formula, X represents an atomic group necessary to complete a benzene ring or a naphthalene ring. These benzene rings and naphthalene rings are methyl groups, ethyl groups,
Alkyl groups such as propyl and butyl groups, aralkyl groups such as benzyl and phenethyl groups, alkoxy groups such as methoxy, ethoxy, propoxy and budoxy groups, dimethylamino, diethylamino, dipropylamino and dibutylamino dialkylamino groups such as dibenzylamino groups, dialkylamino groups such as diphenethylamino groups, diarylamino groups such as diphenylamino groups, ditolylamino groups, cyclic amino groups such as pyrrolidino groups, piperazino groups, morpholino groups, chlorine It can also be substituted with an atom, a halogen atom such as a bromine atom, an iodine atom, etc. _R1 , _R2
and R ₃ is a substituted or unsubstituted alkyl group (e.g., methyl group, ethyl group, propyl group, butyl group, 2-hydroxyethyl group, 2-chloroethyl group, 2-methoxyethyl group, 3-methoxypropyl group, 2-ethoxyethyl group, 3-ethoxypropyl group, etc.), substituted or unsubstituted aralkyl groups (e.g., benzyl group, phenethyl group, chlorobenzyl group, dichlorobenzyl group, trichlorobenzyl group, methylbenzyl group, methoxybenzyl group, dimethoxybenzyl group, dimethylaminobenzyl group, diethylaminobenzyl group, α-naphthylmethyl group, β-naphthylmethyl group) or substituted or unsubstituted aryl group (e.g.
Phenyl group, tolyl group, xylyl group, biphenyl group, methoxyphenyl group, dimethoxyphenyl group, ethoxyphenyl group, chlorophenyl group, dichlorophenyl group, trichlorophenyl group, dimethylaminophenyl group, diethylaminophenyl group , dipropylaminophenyl group, morpholinophenyl group, piperidinophenyl group, cyanophenyl group, hydroxyphenyl group, carboxyphenyl group, α-naphthyl group, β-naphthyl group, etc.). Specific examples of the hydrazone compound represented by the general formula (1) are listed below. Compound example These compounds can be used alone or in combination of two or more. These hydrazone compounds represented by the general formula (1) are represented by the general formula It can be synthesized by a conventional method using an aldehyde represented by the formula (wherein X, R ₁ , R ₂ and R ₃ have the same meanings as above) and hydrazine. Next, the hydrazone compound used in the present invention will be specifically explained using synthesis examples. Synthesis Example (Synthesis of the Exemplified Compound H-1) In a 300 ml three-necked flask, 1000 ml of an aldehyde in which X in general formula (2) is an atomic group necessary to complete a benzene ring, and R ₁ , R ₂ and R ₃ are each a methyl group is added.
g (0.050 mol), 100 ml of ethanol, and 20 ml of acetic acid were added and dissolved. Next, a solution obtained by diluting 1.57 g (0.025 mol) of hydrazine hydrate (80%) with 20 ml of ethanol was added dropwise to this solution, and the mixture was stirred at room temperature for 30 minutes to react. The reaction solution was poured into 3 water and neutralized with sodium carbonate. The obtained precipitate was dried separately and recrystallized repeatedly with acetone to give a melting point of 198.0 to 199.0.
3.69 g of yellow needle crystals (yield based on aldehyde
37%). Elemental analysis Molecular formula C ₂₆ H ₃₀ N ₄ Calculated value Analysis value C 78.34% 78.24% H 7.60% 7.66% N 14.06% 14.01% 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) 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. etc., among which types 3 to 6 are desirable. Furthermore, in the case of four types of photoreceptors, in other words, a hydrazone 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. In this case, the sensitivity of the photoreceptor is particularly improved and the residual potential is also 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 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. The charge transport layer used in the present invention is preferably formed by applying a solution of the hydrazone compound represented by the general formula (1) and a binder dissolved in a suitable solvent and drying the solution. Examples of the binder used here include polysulfone, acrylic resin, methacrylic resin, vinyl chloride resin,
Examples include vinyl acetate resin, phenol resin, epoxy resin, polyester resin, alkyd resin, polycarbonate, polyurethane, and copolymer resins containing two or more of the repeating units of these resins. In particular, polyester resin and polycarbonate are used. This is preferable. 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-tocopherol, 2-
t-octyl-5-chlorohydroquinone, 2,
Examples include phenolic compounds such as 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, perylene pigments, indigo pigments, thioindigo 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 5 microns or less, preferably 0.05 to 3 microns. 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 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 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 ball 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 benzyldimethylamine, α-methylbenzyldimethylamine, 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 pigments 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. In the electrophotographic photoreceptor of the present invention, an intermediate layer may be provided on a suitable support, the above-described charge generation layer may be formed thereon, and a charge transport layer may be formed thereon. This intermediate layer prevents the injection of free charges from the conductive support to the photosensitive layer when the photosensitive layer having a laminated structure is charged, and also serves as an adhesive that holds the photosensitive layer integrally bonded to the conductive support. It shows the action as a layer. This intermediate layer is made of metal oxide such as aluminum oxide, polyethylene, polypropylene, acrylic resin, methacrylic resin, vinyl chloride resin, phenol resin, epoxy resin, polyester resin, alkyd resin, polycarbonate, polyurethane, polyimide resin, vinylidene chloride resin, Vinyl chloride-vinyl acetate copolymer, casein, gelatin, polyvinyl alcohol, water-soluble ethylene-acrylic acid copolymer, nitrocellulose, etc. can be used. The thickness of this intermediate layer or adhesive layer is suitably 0.1 to 5 microns, preferably 0.5 to 3 microns. Furthermore, a laminated structure in which the charge generation layer is provided on the charge transport layer may be used, and in this case, an appropriate surface protection layer may be formed. Further, if necessary, the surface of the charge generation layer can be polished to a mirror finish in order to uniformly inject carriers into the charge transport layer above the charge generation layer. A charge transport layer can be provided on the charge generation layer provided in this manner. 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. In the exposed area where the charged light is exposed, holes generated in the charge generation layer are injected into the charge transport layer and then reach the surface, neutralizing the negative charge and attenuating the surface potential, creating an electrostatic contrast between it and the unexposed area. can be caused. Various conventionally used developing methods can be used for visualization. As another specific example of the electrophotographic photoreceptor of the present invention, for example, the above-mentioned hydrazone compound is used as a charge transport material, and an insulating binder (the binder itself is a charge transport material such as poly-N-vinylcarbazole) is used. A photosensitive layer may be formed on the conductive layer by dispersing the above-mentioned pigment in a charge transport medium (which may be present). The insulating binder and charge transport material used in this case include, for example,
The materials disclosed in Japanese Patent Application Laid-open No. 47-30328, Japanese Patent Application Laid-open No. 47-18545, etc. can be used. The support used in the electrophotographic photoreceptor of the present invention may be any type of conductive layer conventionally used as long as it is imparted with conductivity. Specifically, metal sheets or metals such as aluminum, vanadium, molybdenum, chromium, cadmium, titanium, nickel, copper, zinc, paldium, indium, tin, platinum, gold, stainless steel, and brass are vapor-deposited or laminated. Examples include plastic sheets. 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, the sensitivity is significantly higher than that of electrophotographic photoreceptors using conventional organic photoconductive materials, and moreover, repeated charging and exposure are not required.
There is no increase in bright area potential and no decrease in dark area potential even when the test is performed over 10,000 times. Hereinafter, the present invention will be explained according to examples. 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 1.0g/m ²
An adhesive layer was formed. Next, add 5g of disazo pigment having the following structure and After dispersing 22 g of tyral resin (butyralization degree 63 mol%) in 95 ml of ethanol,
A charge generation layer was formed by coating on the adhesive layer and having a coating weight of 0.2 g/m ² after drying. Next, 5 g of the hydrazone compound (H-1), 5 g of poly-4,4'-dioxydiphenyl group-2,2-propane carbonate (viscosity average molecular weight 30,000)
g dissolved in 150 ml of dichloromethane was applied onto the charge generation layer 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 5KV using an electrostatic copying paper tester 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 its charging properties. The charging characteristics of this photoreceptor are shown using the initial potential Vo (V), the potential retention rate for 10 seconds in the dark as Rv (%), and the half-attenuation exposure amount E _1/2 (lux·sec). Vo: 630V Rv: 93% E _1/2 : 5.1lux·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 (Vylon 200, Toyobo Co., Ltd.) and 5 g of the exemplified hydrazone compound in 150 ml of dichloromethane was applied onto the charge generation layer and dried, resulting in charge transport with a coating weight of 11 g/ ^m2. formed a layer. 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】

[Table] Example 11 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 electrophotographic photosensitive plate thus prepared was examined for charging characteristics in the same manner as in Example 1, and the results are shown below. Vo: 670V Rv: 91% E _1/2 : 3.2lux・sec Example 12 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 after dispersion,
It was applied onto the casein layer of the aluminum plate provided with the casein layer used in Example 1, and the coating amount after drying was 10.
g/ ^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: 550V Rv: 88% E _1/2 : 18.3lux·sec Example 13 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,
After turning off the high frequency power supply and waiting for the substrate 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 exactly the same manner as in Example 1. The photoreceptor thus obtained was placed in a charging 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. Immediately thereafter, a good toner image was obtained on the photoreceptor surface by 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 at least one compound represented by the following general formula (1). General formula (1) (In the formula, X represents an atomic group necessary to complete a substituted or unsubstituted benzene ring or a substituted or unsubstituted naphthalene ring. _{R 1} , R ₂ and R ₃ are
It represents a substituted or unsubstituted alkyl group, a substituted or unsubstituted aralkyl group, or a substituted or unsubstituted aryl group. )