JPH0513501B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to an electrophotographic photoreceptor, and more particularly to an electrophotographic photoreceptor having a photosensitive layer containing a hydrazone compound as an organic photoconductive substance. [Prior art] Conventional electrophotographic photoreceptors include those using inorganic photoconductive substances such as selenium, cadmium sulfide, and zinc oxide, photoconductive polymers typified by poly-N-vinylcarbazole, and 1-phenyl- 3-(p
-Diethylaminostyryl)-5-(p-diethylaminophenyl)pyrazoline and other low-molecular organic photoconductive substances are known. [Problems to be Solved by the Invention] The present inventors have discovered that in the case of a low-molecular organic photoconductive substance, it is possible to form a photosensitive layer with good film formability by combining it with an appropriate binder resin. As a result of intensive research into low-molecular organic photoconductive substances, the present inventors discovered that a photoreceptor with excellent electrophotographic properties could be obtained by using a hydrazone compound represented by the general formula () below in the photosensitive layer, and the present invention was achieved. It is something. [Means for Solving the Problems] According to the present invention, an electrophotographic photoreceptor having a photosensitive layer containing at least one hydrazone compound represented by the following general formula () as a photoconductive substance: (In the formula, R ₁ and R ₂ each represent a hydrogen atom, a substituted or unsubstituted aryl group, or a substituted or unsubstituted heterocyclic group, except when R ₁ and R ₂ are both hydrogen atoms, R ₃ , R ₄ , R ₅ and R ₆ each represent a hydrogen atom or a substituted or unsubstituted alkyl group). In the above general formula, the aryl group in the definition of R ₁ and R ₂ is, for example, a phenyl group, a naphthyl group, an anthryl group, and the heterocyclic group is, for example, a monovalent group derived from pyridine, quinoline, carbazole, phenothiazine, or phenoxazine. It is a heterocyclic group. The above aryl group and heterocyclic group can have a substituent or an atom. Examples of substituents for the aryl group include di-substituted amino groups (e.g., dimethylamino, diethylamino, dipropylamino, dibutylamino, dibenzylamino, diphenylamino, ditolylamino, dixylylamino), cyclic amino groups (e.g., morpholino,
pyrrolidino, piperidino) or alkoxy groups (eg, methoxy, ethoxy, propoxy, butoxy). Furthermore, aryl and heterocyclic groups can be grouped by alkyl groups (e.g. methyl, ethyl, n-propyl, isopropyl, n-butyl, t-butyl, amyl, t-amyl), halogen atoms (e.g. chlorine, bromine, iodine). It can also be replaced. Further, in the definitions of R ₃ , R ₄ , R ₅ and R ₆ , examples of the substituent for the alkyl group include a halogen atom, a hydroxyl group, and an alkoxy group. Specifically, substituted or unsubstituted alkyl groups include methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, t-butyl, n
-amyl, t-amyl, n-octyl, 2-ethylhexyl, t-octyl, 2-hydroxyethyl, 3-hydroxypropyl, 2-chloroethyl, 3-chloropropyl, 2-methoxyethyl,
Examples include 3-methoxypropyl. Specific examples of the hydrazone compound represented by general formula (1) are shown below. Compound example The hydrazone compound represented by the general formula (1) used in the present invention is represented by the general formula (2). (In the formula, R ₃ , R ₄ , R ₅ and R ₆ have the above definitions) and a salt thereof and the general formula (3) (where R ₁ and R ₂ are as described above) can be obtained by a condensation reaction in alcohol in the presence of a small amount of glacial acetic acid or acetic acid added as necessary. can. Synthesis example (synthesis of the hydrazone compound H-1): In general formula (2), R ₃ is a hydrogen atom; R ₄ , R ₅ , R ₆
12.05g of hydrazine, each consisting of a methyl group
(0.064 mol), 11.35 g (0.064 mol) of a carbonyl compound consisting of general formula (3) in which R ₁ is a P-diethylaminophenyl group and R ₂ is a hydrogen atom, 100 ml of ethanol, and 100 ml of acetic acid were mixed, and the mixture was heated at room temperature for 1 hour. The mixture was stirred and reacted. After the reaction, this solution was poured into water, and the resulting precipitate was dried separately. This solid was purified by recrystallization using MEK to obtain 7.56 g (yield: 34%) of crystals. Elemental analysis Molecular formula C ₂₃ H ₂₉ N ₃ Calculated value Analytical value C 79.50% 79.47 H 8.41% 8.43 N 12.09 12.10 Other hydrazone compounds used in the present invention can be synthesized in the same manner. As the electrophotographic photoreceptor containing the hydrazone compound represented by the general formula (1), any type of electrophotographic photoreceptor using an organic photoconductive substance can be applied, but preferred types include (1) A charge-transfer complex is formed by combining an electron-donating substance and an electron-accepting substance, (2) an organic photoconductor sensitized by adding a dye, and (3) a pigment dispersed in a hole matrix. , (4) those whose functions are separated into a charge generation layer and a charge transport layer, (5) those whose main components are a eutectic complex consisting of a dye and a resin and an organic photoconductor, and (6) those whose main components are an organic photoconductor in a charge transfer complex. There are also types to which an inorganic charge-generating material is added, among which types (3) to (6) are preferable. Furthermore, when using a photoreceptor of type (4),
In other words, when a hydrazone compound represented by the general formula (1) is used as a charge transport material for the charge transport layer of a photoreceptor that has two functionally separated layers: a charge generation layer and a charge transport layer, the sensitivity of the photoreceptor is particularly good. 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 (4) type photoreceptor will be explained. As for the layer structure, a conductive layer, a charge generation layer, and a charge transport layer are essential, and the charge generation layer may be either above or below the charge transport layer. 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 can be provided on the conductive layer for the purpose of improving the adhesion between the conductive layer and the charge generation layer. 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 are used. The appropriate thickness of the adhesive layer is 0.1 to 5μ, preferably 0.5 to 3μ. 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. The charge generation layer is provided by means such as vacuum deposition, sputtering, glow discharge or coating depending on the type of charge generation material used. When coating,
When the charge generating material is provided without a binder,
It may be provided as a resin dispersion or as a homogeneous solution of a binder and a charge generating material. When the charge generation layer is formed by applying a resin dispersion or solution of the charge generation material, the ratio of the binder in the charge generation layer is preferably 80% or less, since a large amount of binder used will affect the sensitivity.
40% or less is desirable. As the binder used in the charge generation layer, various conventionally used resins such as polyvinyl butyral can be used. A charge transport layer is provided on the charge generation layer provided by any of the above methods. The thickness of the charge transport layer is 5~
30μ, preferably 8-20μ. Since the hydrazone compound used in the present invention does not have a film-forming ability by itself, a solution dissolved in a suitable organic solvent together with various binder resins is applied by a conventional method and dried to form a charge transport layer. As the binder, various conventionally used binders such as acrylic resin and polycarbonate resin can be used. It is also possible to use photoconductive polymers which themselves have charge transport capabilities, such as poly-N-vinylcarbazole, as binders. 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 and neutralize the negative charge, causing the surface potential to attenuate and create an electrostatic charge between the exposed area and the unexposed area. A contest test occurs. Various conventionally used developing methods can be used for visualization. The purpose of the photoconductor of the present invention is to prevent deterioration caused by ultraviolet rays, ozone, etc., contamination by oil, damage caused by metal cutting powder, or damage or scraping caused by photoconductor contact members such as developing members, transfer members, and cleaning members. A protective layer may be further provided on the charge transport layer. In order to form an electrostatic latent image on this protective layer, it is desirable that the surface resistivity is 10 ¹¹ Ω or more. Such protective layers include polyvinyl butyral, polyester, polycarbonate, acrylic resin,
Methacrylic resin, nylon, polyimide, polyarylate, polyurethane, styrene-butadiene copolymer, styrene-acrylic acid copolymer,
A solution prepared by dissolving a resin such as styrene-acronitrile copolymer in an organic solvent is applied onto the photosensitive layer.
Formed by drying. Moreover, additives such as ultraviolet absorbers can be added to the resin liquid. The thickness of the protective layer is generally 0.05 to 20 microns, especially 0.2 to 5 microns.
Microns are preferred. Regarding photoreceptors other than the above-mentioned type (4), detailed explanations are omitted here because they are well known in numerous documents published so far. 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 An ammonia aqueous solution of casein (11.2 g of casein, 1 g of 28% ammonia water, 222 g of water) was placed on an aluminum plate.
ml) with a Mayer bar and dry, coating amount 1.0
An adhesive layer of g/m ² was formed. Next, 5 g of a disazo pigment having the following structure and 2 g of butyral resin (degree of butyralization: 63 mol%) were dissolved in 95 ml of ethanol. After being dispersed with the liquid, it was coated on the adhesive layer to form a charge generation layer having a coating weight of 0.2 g/m ² after drying. Next, 5 g of exemplified hydrazone compound H-1 and 5 g of poly-4,4'-dioxydiphenyl-2,2-propane carbonate (viscosity average molecular weight 30,000) were added.
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 tested using an electrostatic copying paper tester manufactured by Kawaguchi Electric Co., Ltd.
5kV statically using ModelSP-428
After corona charging and holding in the dark for 10 seconds, the illuminance
The charging characteristics were investigated by exposure at 5 lux. The initial potential is Vo (V), the potential retention rate for 10 seconds in the dark is Rv (%), and the half-decay exposure amount is E1/2 (lux.sec).
The charging characteristics of this photoreceptor are shown below. Vo-620V, Rv 99%, E1/2 9.7lux.sec Examples 2 to 10 A pigment having the following structure was vacuum deposited on an aluminum plate with a thickness of 100μ to form a charge generation layer with a thickness of 0.15μ. Next, 5 g of polyester resin (Vylon 200, Toyobo Co., Ltd.) and the above-mentioned hydrazone compound H-2
A solution prepared by dissolving 5 g of ~H-10 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 produced electrophotographic photoreceptor were examined in the same manner as in Example 1. The results are shown in the table below.

[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 applied and dried to give a coating weight of 11 g/m ² . The charging characteristics of the produced electrophotographic photoreceptor were examined in the same manner as in Example 1. Vo-575V, Rv 97%, E1/2 7.4lux.sec Example 12 5g of the hydrazone compound H-1 used in Example 1 and poly-N-vinylcarbazole (molecular weight 30
1.0g of β-type copper phthalocyanine was added to a solution of 5g) dissolved in 150ml of dichloromethane, and after dispersion,
It was applied and dried on the casein layer of the aluminum plate provided with the casein layer used in Example 1, and the coating amount was 10 g/m ²
And so. Example 1: Charging measurement of the produced electrophotographic photoreceptor
The following characteristic values were obtained in the same manner as above. However, the charging polarity was set to +. Vo+485V, Rv 87%, E1/2 22.8lux.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 the gas flow rate and the main valve of the deposition tank were adjusted to stabilize the temperature at 0.5 torr. 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 temperature inside the tank was reduced 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 positively charged developer (including toner and carrier) was cascaded onto the photoreceptor surface to obtain a good toner image on the photoreceptor surface.

Claims (1)

[Scope of Claims] 1. An electrophotographic photoreceptor having a photosensitive layer containing at least one hydrazone compound represented by the following general formula () as a photoconductive substance: (In the formula, R ₁ and R ₂ each represent a hydrogen atom, a substituted or unsubstituted aryl group, or a substituted or unsubstituted heterocyclic group, except when R ₁ and R ₂ are both hydrogen atoms, R ₃ , R ₄ , R ₅ and R ₆ each represent a hydrogen atom or a substituted or unsubstituted alkyl group)