JPH0117570B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a photoreceptor, and more particularly to a novel electrophotographic photoreceptor containing a hydrazone derivative as an active ingredient in a photosensitive layer. Conventionally, photoreceptors having a photosensitive layer containing as a main component an inorganic photoconductor such as selenium, zinc oxide, or cadmium sulfide have been widely used. However, selenium photoreceptors crystallize under high temperature conditions and deteriorate electrophotographic performance, zinc oxide photoreceptors and cadmium sulfide photoreceptors have poor moisture resistance and printing durability, and selenium and cadmium sulfide are toxic. It has various drawbacks, such as restrictions on manufacturing and handling due to the high amount of carbon dioxide. On the other hand, electrophotographic photoreceptors having a photosensitive layer containing an organic photoconductive compound as a main component are relatively easy to manufacture, are inexpensive, and generally have superior thermal stability compared to selenium photoreceptors. It has many uses, and has attracted a lot of attention in recent years.
Poly N-vinylcarbazole is the most well-known such organic photoconductive compound, and electrophotographic photoreceptors using it have been put into practical use, but it has poor sensitivity and printing durability. It's not completely satisfying. On the other hand, various low-molecular organic photoconductive compounds have been proposed; for example, US Pat. No. 3,189,447
2,5-bis(p-diethylaminophenyl)-1,3,4-oxadiazole described in the specification has poor compatibility with the binder and does not provide a homogeneous and stable photosensitive layer. It is difficult to
The diarylalkane derivatives described in No. 3820989 have good compatibility with binders, but
Since it has low stability against light, it has the disadvantage that the sensitivity of the photoreceptor gradually decreases with repeated use. Furthermore, various electrophotographic photoreceptors containing hydrazone derivatives as active ingredients have been proposed. For example, JP-A-54-81847, JP-A-54-150128.
Publication No. 1987-46760, Japanese Patent Publication No. 1983-46760
Publication No. 52063, Japanese Unexamined Patent Application Publication No. 55-52064, etc. are known. Some of these have already been put into practical use, but some have insufficient electrophotographic performance such as sensitivity and residual potential characteristics, and even if the initial characteristics are good, the sensitivity decreases with repeated use or the residual potential gradually decreases. Many of them have poor stability of properties when used repeatedly, such as accumulation, and are also unstable to ultraviolet light, so it has not been possible to find a material that fully satisfies the requirements for electrophotographic photoreceptors. This is the actual situation. An object of the present invention is to provide a photoreceptor containing a carrier transport material that has excellent compatibility with a binder and excellent carrier transport ability. Another objective is to have excellent charging characteristics, sensitivity characteristics, and image forming characteristics, and especially excellent discharge efficiency in the low electric field region (E ⁵⁰⁰ ₅₀ ), so-called sharp sensitivity characteristics, and no fogging. An object of the present invention is to provide an electrophotographic photoreceptor that can stably obtain clear copied images. Other objects of the invention will become apparent from the description. In order to achieve the above object, the present inventors, as a result of intensive research, have discovered that the object can be achieved by using a specific hydrazone derivative as a carrier transport substance, and have completed the present invention. . The above object is achieved by providing a photosensitive layer containing a hydrazone derivative represented by the following general formula [] on a conductive support. General formula [] In the formula, Ar ₁ and Ar ₂ represent substituted/unsubstituted aryl groups, and preferred aryl groups include phenyl group,
Naphthyl and anthryl groups, and preferred substituents thereof include alkyl groups having 1 to 5 carbon atoms, alkoxy groups having 1 to 5 carbon atoms, halogen atoms, hydroxyl groups, substituted amino groups,
R ₁ represents a substituted/unsubstituted alkyl group, a substituted/unsubstituted aralkyl group, or a substituted/unsubstituted aryl group, and preferred alkyl groups include an alkyl group having 1 to 8 carbon atoms, and a preferred aralkyl group. As a group, benzyl group, phenethyl group,
A preferred aryl group is a phenyl group, and preferred substituents thereof include an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a halogen atom, a hydroxyl group, and a substituted amino group. It is. R ₂ represents a hydrogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aryl group, and a preferable alkyl group is an alkyl group having 1 to 4 carbon atoms, and a preferable aryl group is phenyl. represents a group. Preferred substituents for the phenyl group include 1 to 4 carbon atoms.
an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a hydroxyl group, a halogen atom, and a substituted amino group. R ₃ is a hydrogen atom, a substituted or unsubstituted alkyl group,
Represents an alkoxy group, a hydroxyl group, a halogen atom, a substituted amino group, preferably a hydrogen atom, a methyl group, an ethyl group, a propyl group, a butyl group, a methoxy group, an ethoxy group, a propioxy group, a butoxy group,
They are hydroxyl group, chlorine atom, bromine atom, fluorine atom, and dialkylamino group. Specific examples of the hydrazone derivatives useful in the present invention represented by the above general formula [] include those having the following structural formula. The above hydrazone derivatives can be easily synthesized by known methods. For example, a hydrazone derivative represented by the general formula [] can be obtained by reacting hydrazine and a carbonyl compound represented by the following general formulas [] and [], respectively, in the presence of an acid catalyst in a solvent such as alcohol. . Here, Ar ₁ , Ar ₂ , R ₁ , R ₂ and R ₃ represent the same groups as in the general formula []. Next, a typical method for synthesizing the hydrazone derivative used in the present invention will be specifically explained. Synthesis example (synthesis of exemplified compound A-(3)) 29 g of 1-methyl-1-phenylhydrazine
(0.24mole) and N-anisylcarbazole-3-
60g (0.2mole) of carbaldehyde and ethanol
The mixture was dissolved in 800 ml, added with 50 ml of acetic acid, and heated under reflux for 1 hour. The precipitate that was left to cool was collected by filtration and recrystallized twice from a mixed solvent of methyl ethyl ketone and ethanol. Yield: 64.1g 79.1% Melting point: 147.5°C to 149.°C A molecular ion peak of m/e=405 was confirmed by FD-Mass, which confirmed that the target product was obtained. Since the hydrazone derivative used in the present invention does not have a film-forming ability by itself, it is used in combination with various binders to form a carrier transport layer constituting the photosensitive layer. Any binder can be used here, but it is preferable to use a film-forming polymer that is hydrophobic, has a high conductivity, and is electrically insulating. Examples of such high molecular weight polymers include the following, but the binder used in the present invention is not limited to these. B-(1) Polycarbonate B-(2) Polyester B-(3) Methacrylic resin B-(4) Acrylic resin B-(5) Polyvinyl chloride B-(6) Polyvinylidene chloride B-(7) Polystyrene B- (8) Polyvinyl acetate B-(9) Polyvinyl butyral B-(10) Vinylidene chloride-acrylonitrile copolymer B-(11) Vinyl chloride-vinyl acetate copolymer B-(12) Vinyl chloride-vinyl acetate-maleic anhydride Acid copolymer B-(13) Silicone resin B-(14) Silicone-alkyd resin B-(15) Phenol-formaldehyde resin B-(16) Styrene-alkyd resin B-(17) Styrene-butadiene copolymer B -(18) Poly-N-vinylcarbazole These binders can be used alone or in combination of two or more. The carrier transport layer as described above absorbs light and
By combining it with any carrier-generating substance selected from various carrier-generating substances, a laminated type or dispersion type photosensitive layer can be constructed. Examples of carrier generating substances that can be effectively used in the present invention include the following. C-(1) Selenium and selenium alloys C-(2) Inorganic photoconductors such as CdS, CdSe, CdSSe, HgS, etc. C-(3) Perylene dyes such as perylenic anhydride and perlenic acid diimide C-(4) Indigoid dye C-(5) Polycyclic quinones such as anthraquinones, pyrenequinones, flavanthrones, anthanthrones C-(6) Bisbenzimidazole dye C-(7) Quinacridone dye C-(8 ) Azo dyes such as monoazo dyes, bisazo dyes, and trisazo dyes C-(9) Indanthrone dyes C-(10) Squarylium dyes C-(11) Phthalocyanine dyes C such as metal-free phthalocyanine and metal phthalocyanine -(12) A charge transfer complex formed from an electron-donating substance such as poly-N-vinylcarbazole and an electron-accepting substance such as trinitrofluorenone.-(13) A charge transfer complex formed from a pyrylium salt or a thiapyrylium salt and a polycarbonate. These carrier-generating substances may be used not only as a single type but as a mixture of two or more types, and if a carrier-generating layer cannot be formed alone, they may be used by dispersing and mixing with a binder. , in this case the binder is
For example, any binder used for carrier transport layers may be selected. To explain the layer structure of the electrophotographic photoreceptor of the present invention, in the present invention, as shown in FIGS. and a carrier transport layer 3 containing the above-mentioned hydrazone derivative as a main component of the carrier transport substance. As shown in FIGS. 3 and 4, this photosensitive layer 4 may be provided on the conductive support 1 via an intermediate layer 5. When the photosensitive layer 4 has a two-layer structure in this manner, an electrophotographic photoreceptor having the best electrophotographic properties can be obtained. Further, in the present invention, as shown in FIGS. 5 and 6, a carrier generating substance 7 in the form of fine particles is dispersed in a layer 6 containing the carrier transport substance as a main component. The photosensitive layer 4 may be provided directly on the conductive support 1 or via an intermediate layer 5. When the photosensitive layer 4 has a two-layer structure, which of the carrier generation layer 2 and the carrier transport layer 3 is to be the upper layer is determined depending on whether the charging polarity is positive or negative. That is, in the case of negative charging, it is advantageous to use the carrier transport layer 3 as an upper layer because the hydrazone derivative of the present invention is a substance having a high transport ability for holes. The carrier generation layer 2 constituting the two-layered photosensitive layer 4 can be applied directly to the conductive support 1 or the carrier transport layer 3, or by providing an intermediate layer such as an adhesive layer or a barrier layer as necessary. can be formed by the following method. D-(1) Vacuum evaporation method D-(2) Method of applying a solution of a carrier-generating substance dissolved in a suitable solvent D-(3) Forming the carrier-generating substance into fine particles in a dispersion medium using a ball mill, homogenizer, etc. The carrier generation layer 2 formed in this way preferably has a thickness of 0.01 to 5 microns. , more preferably 0.05 micron to 3 micron. The thickness of the carrier transport layer 3 can be changed as necessary, but it is usually preferably 5 microns to 30 microns. The composition ratio of the carrier transport material and the binder in the carrier transport layer 3 is preferably 0.8 to 4 parts by weight of the binder per 1 part by weight of the carrier transport material 1. When forming the photosensitive layer 4 in which the generating substance is dispersed, it is preferable to use the binder in an amount of 10 parts by weight or less per 1 part by weight of the carrier generating substance. When the carrier generating layer 2 is formed by dispersing and mixing a binder, it is preferable to use the binder in an amount of 5 parts by weight or less per 1 part by weight of the carrier generating substance. The conductive support 1 used in the construction of the electrophotographic photoreceptor of the present invention may be a metal plate such as an aluminum plate or a stainless steel plate, or a support such as paper or plastic film.
A thin layer of a metal such as palladium or gold provided by lamination or vapor deposition, or a layer of a conductive compound such as a conductive polymer, indium oxide, or tin oxide, coated on a support such as paper or plastic film. Alternatively, those provided by vapor deposition may be used. As the intermediate layer 5 such as an adhesive layer or a barrier layer, in addition to the high molecular weight polymer used as a binder for the photosensitive layer, aluminum oxide or the like is used. The electrophotographic photoreceptor of the present invention has the above-described structure, and as is clear from the examples described later, it has excellent charging characteristics, sensitivity characteristics, and image forming characteristics, and is particularly excellent in discharge characteristics in a low electric field region. It has excellent efficiency and so-called sharp sensitivity characteristics, and can stably obtain clear copied images without fogging even after repeated use. Example 1 Vinyl chloride-vinyl acetate-maleic anhydride copolymer ``Eslec MF-'' was deposited on a conductive support made by vapor-depositing aluminum on a polyester film.
10" (manufactured by Sekisui Chemical Co., Ltd.) with a thickness of 0.05 microns, and on top of that is a dibromoanthrone "Monolite Red 2Y" (manufactured by ICI, CI No. 10).
59300) to form a carrier generation layer with a thickness of 0.5 microns. Furthermore, exemplified compound A-
(21) 2 parts by weight and 3 parts by weight of polycarbonate "Panlite L-1250" (manufactured by Teijin Chemicals), 1,
A carrier transport layer was formed by coating a solution dissolved in 30 parts by weight of 2-dichloroethane so that the film thickness after drying was 12 microns, thereby producing an electrophotographic photoreceptor of the present invention. The electrophotographic properties of this electrophotographic photoreceptor were measured by a dynamic method using an electrostatic copying paper testing device "Model Sp-428" (manufactured by Kawaguchi Electric Seisakusho). That is, the surface of the photosensitive layer of the photoreceptor is charged with a -
Surface potential VA when charged at 6.0kV for 5 secondsNext, light from a tungsten lamp is applied to the photoreceptor surface so that the illumination intensity is 35lux, and it is necessary to attenuate the surface potential from -500V to -250V. The exposure amount (half-reduced exposure amount) E ⁵⁰⁰ ₂₅₀ (lux·sec) and the exposure amount E ⁵⁰⁰ ₅₀ (lux·sec) required to attenuate the surface potential from −500 V to −50 V were determined. Further, similar measurements were repeated 50 times. The results are shown in Table 1. Comparative Example 1 Except that a hydrazone derivative represented by the following structural formula was used instead of Exemplified Compound (21) as a carrier transport substance. A comparative electrophotographic photoreceptor was prepared in the same manner as in Example 1, and the same measurements as in Example 1 were carried out. The results are shown in Table 1.

[Table] As is clear from the above results, the electrophotographic photoreceptor of the present invention has higher sensitivity than the comparative electrophotographic photoreceptor, and is particularly excellent in sensitivity at E ⁵⁰⁰ ₅₀ . Examples 2 to 6 Same as Example 1 except that Exemplified Compounds (22), (23), (24), (25) and (26) were used instead of Exemplified Compound 1 as carrier transport substances. An electrophotographic photoreceptor of the present invention was prepared. Measurements were carried out on these electrophotographic photoreceptors in the same manner as in Example 1, and the results shown in Table 2 were obtained.

[Table] Example 7 An intermediate layer of 0.1 micron thick made of polyester "Vylon 200" (manufactured by Toyobo Co., Ltd.) was provided on a conductive support made of laminated aluminum foil, and then the structure represented by the following structural formula was formed. Dissolve 1 part by weight of bisazo dye in 120 parts by weight of a mixture of ethylenediamine, n-butylamine, and tetrahydrofuran at weight ratios of 1.2:1.0:2.2. A carrier generation layer was formed by applying the solution so that the amount of adhesion after drying was 0.2 g/m ² . Furthermore, a solution obtained by dissolving 12 parts by weight of the exemplified compound as a carrier transport substance and 3 parts by weight of polycarbonate "Panlite L-1250" (manufactured by Teijin Kasei) in 30 parts by weight of 1,2-dichloroethane was added. A carrier transport layer was formed by coating to a film thickness of 15 microns after drying, thereby producing an electrophotographic photoreceptor of the present invention. When this electrophotographic photoreceptor was measured in the same manner as in Example 1, the results shown in Table 3 were obtained. This electrophotographic photoreceptor was also used in an electrophotographic copying machine "U".
−Bix2000R” (manufactured by Konishiroku Photo Industry Co., Ltd.),
In order to investigate the degree of electronic fatigue deterioration (sensitivity change due to repeated use) by repeating a quasi-process consisting of charging, exposure, and cleaning steps, we applied an exposure amount of 6 lux sec to the surface of the photosensitive layer during exposure. When we investigated how the surface potential of the photoreceptor changes by repeating the above-mentioned quasi-process, we obtained the results shown in FIG. (Curve 1) Comparative Example 2 Same as Example 7 except that a hydrazone derivative represented by the following structural formula was used as a carrier transport substance. A comparative electrophotographic photoreceptor was prepared in the same manner. This comparative electrophotographic photoreceptor was measured in the same manner as in Example 7, and the results shown in Table 3 and FIG. 7 (curve 2) were obtained.

[Table] As is clear from the above results, the electrophotographic photoreceptor of the present invention has superior sensitivity characteristics compared to comparative electrophotographic photoreceptors, and has extremely stable characteristics with little fatigue deterioration even after repeated use. have. Examples 8 to 12 Exemplary compounds (2), (3), as carrier transport substances
An electrophotographic photoreceptor of the present invention was prepared in the same manner as in Example 7 except that (5), (10), and (16) were used. The same measurements as in Example 1 were carried out on these electrophotographic photoreceptors, and the results shown in Table 4 were obtained.

[Table] Example 13 A 0.1 micron thick intermediate layer made of vinyl chloride, vinyl acetate, and maleic anhydride copolymer "Elex MF-10" (manufactured by Sekisui Chemical Co., Ltd.) on a conductive support coated with aluminum. 2 parts by weight of bisazo dye represented by the following structural formula and 1 part by weight of polycarbonate "Iupilon S-1000" (manufactured by Mitsubishi Gas Chemical Co., Ltd.) were added thereto in 1,2-dichloroethane.
150 parts by weight The mixture was well dispersed and mixed and coated to a dry film thickness of 0.5 microns to form a carrier generation layer. Furthermore, on top of that, a solution prepared by dissolving 2 parts by weight of Exemplified Compound (16) and 3 parts by weight of polymethyl methacrylate "Acripet" (manufactured by Mitsubishi Rayon Co., Ltd.) in 30 parts by weight of 1,2-dichloroethane was added to the film with a film thickness of 12 parts by weight after drying. The electrophotographic photoreceptor of the present invention was prepared by applying the resin in a micron thickness. This electrophotographic photoreceptor was measured in the same manner as in Example 1.
Obtained the results in the table. Comparative Example 3 A comparative electrophotographic photoreceptor was prepared in the same manner as in Example 13, except that a hydrazone derivative represented by the following structural formula was used as a carrier transport material. When this comparative electrophotographic photoreceptor was measured in the same manner as in Example 1, the results shown in Table 5 were obtained.

[Table] As is clear from the above results, the electrophotographic photoreceptor of the present invention has superior sensitivity characteristics compared to the comparative electrophotographic photoreceptor, and is particularly excellent at E ⁵⁰⁰ ₅₀ , producing clear copied images without fog. You can expect to get it. Example 14 When the electrophotographic photoreceptor of the present invention prepared in Example 13 was installed in an electrophotographic copying machine "U-Bix2000R" (manufactured by Konishiroku Photo Industry Co., Ltd.) and an image was copied, it was found that it was faithful to the original image. A clear copy image with excellent contrast and gradation and no fogging was obtained. this is
Even after repeating the process 20,000 times, we were able to obtain images as good as the initial one.

[Brief explanation of drawings]

1 to 6 are sectional views showing examples of the mechanical structure of the electrophotographic photoreceptor of the present invention, respectively. 1... Conductive support, 2... Carrier generation layer,
3... Carrier transport layer, 4... Photosensitive layer, 5... Intermediate layer, 6... Layer containing a carrier transport substance, 7
...Carrier generating substance FIG. 7 shows the results of Example 7 and Comparative Example 2.

Claims (1)

[Scope of Claims] 1. A photoreceptor comprising a photosensitive layer containing a carrier-generating substance and a carrier-transporting substance on a conductive support, wherein the carrier-transporting substance is a hydrazone derivative represented by the following general formula []. A photoreceptor characterized by: General formula [] However, in the formula, Ar ₁ and Ar ₂ are substituted/unsubstituted aryl groups, R ₁ is substituted/unsubstituted alkyl groups,
Substituted/unsubstituted aralkyl group, substituted/unsubstituted aryl group, R ₂ is a hydrogen atom, substituted/unsubstituted alkyl group, substituted/unsubstituted aryl group, R ₃ is
Represents a hydrogen atom, a substituted or unsubstituted alkyl group, an alkoxy group, a hydroxyl group, a halogen atom, or a substituted amino group. 2. Claim 1, wherein the photosensitive layer is constituted by a laminate of a carrier-generating layer containing a carrier-generating substance as a main component and a carrier-transporting layer containing a carrier-transporting substance as a main component.
Photoreceptor described in section.