JP2909184B2 - Diphenylamine-based compound and electrophotographic photoreceptor containing the compound - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[Industrial Application Field] The present invention relates to a novel diphenylamine compound and an electrophotographic photoreceptor containing the compound. [Prior art] In general, in electrophotography, an electrostatic latent image is formed by charging and exposing the surface of a photosensitive layer of a photoreceptor, developing this with a developer, visualizing the latent image, and directly converting the visible image as it is. A direct method of fixing a photoreceptor to obtain a copy image, a powder image transfer method of transferring a visible image on a photoreceptor onto a transfer material such as paper, and fixing the transferred image to obtain a copy image, or a photosensitive method. 2. Related Art A latent image transfer method of transferring an electrostatic latent image on a body onto transfer paper, and developing and fixing the electrostatic latent image on the transfer paper is known. As a material constituting a photosensitive layer of a photoreceptor used in this type of electrophotography, conventionally, selenium, cadmium sulfide,
Inorganic photoconductive materials such as zinc oxide are known. [Problems to be Solved by the Invention] These photoconductive materials have a number of advantages, such as a small amount of charge dissipation in a dark place or an ability to quickly dissipate charge by light irradiation. On the other hand, it has various disadvantages. For example, in the case of a selenium-based photoconductor, manufacturing conditions are difficult, the manufacturing cost is high, and the selenium-based photoconductor is susceptible to heat and mechanical shock.
Cadmium sulfide photoreceptors and zinc oxide photoreceptors do not provide stable sensitivity in humid environments, and dyes added as sensitizers cause charge deterioration due to corona charging and photobleaching due to exposure, resulting in long-term However, there is a disadvantage that stable characteristics cannot be provided over a wide range. On the other hand, various organic photoconductive polymers such as polyvinyl carbazole have been proposed, but these polymers are superior to the above-mentioned inorganic photoconductive materials in terms of film-forming properties and lightness. However, they are still inferior to inorganic photoconductive materials in terms of sufficient sensitivity, durability and stability due to environmental changes. The low molecular weight organic photoconductive compound is preferable in that the physical properties or electrophotographic properties of the film can be controlled by selecting the type and composition ratio of the binder used in combination. , High compatibility with the binder is required. A photoreceptor in which these high and low molecular weight organic photoconductive compounds are dispersed in a binder resin has drawbacks such as a large residual potential and low sensitivity due to a large number of carrier traps. Therefore, it has been proposed to solve the above-mentioned drawbacks by blending a charge transport material with a photoconductive compound. Also, a function-separated type photoreceptor has been proposed in which the charge generation function and the charge transport function of the photoconductive function are shared by different substances. In such a function-separated type photoreceptor, many organic compounds are mentioned as the charge transporting material used for the charge transporting layer, but there are various problems in practice. For example, 2,5-bis (p-diethylaminophenyl) 1,3,4-oxadiazole described in U.S. Pat. No. 3,189,447 has low compatibility with a binder and tends to precipitate crystals. U.S. Patent 3,820,989
The diarylalkane derivative described in Japanese Patent Application Laid-Open Publication No. H08-27139 has good compatibility with a binder, but changes in sensitivity when used repeatedly. The hydrazone compounds described in JP-A-54-59143 have relatively good residual potential characteristics, but have the drawback of inferior chargeability and repetition characteristics. As described above, in reality, there is almost no low-molecular-weight organic compound having practically preferable characteristics in producing a photoreceptor. Also, Japanese Patent Application Laid-Open No. 57-11350 discloses the following formula (IV): [Wherein, R ¹ , R ² , R ³ and R ⁴ represent those described in the above-mentioned publication]. JP-A-58-131954 discloses the following formula (V) [Wherein R ¹ , R ² , R ³ , and R ⁴ represent those described in the above publication]. Also, JP-A-2-210451 discloses the following formula (VI) [Wherein R ¹ , R ² , R ³ , Ar ¹ , Ar ² , Ar ³ , and Ar ⁴ represent those described in the above-mentioned publication]. However, the compounds of formulas (IV) and (V) have completely different structures from the compounds of the present application. Although the compounds of the formula (VI) have a structure similar to the compounds of the present application, they have a vinyl group [-CH = C = (Ar ³ , Ar ⁴ )] and a hydrazone group [-CH = NN = ( Ar ¹ , Ar ² )] are attached to the 4-position and 4′-position of diphenylamine, so that the affinity for the binder for forming the charge transport layer is poor, and the drying step after coating the charge transport layer or the photosensitive step During use, the charge transport layer is separated from the photoreceptor substrate. The present invention has been made in view of the above facts, and has a good compatibility with a binder, a good affinity, and a novel diphenylamine-based compound having an excellent charge transporting ability and a sensitivity containing the diphenylamine-based compound. It is an object of the present invention to provide a photoreceptor which is excellent, has less fatigue deterioration upon repeated use, and has stable electrophotographic characteristics. [Means for Solving the Problems] As a result of intensive studies to solve the above problems, the present inventors have found that the following general formula (I) [In the formula (I), Ar ¹ , Ar ² , Ar ³ and Ar ⁴ each independently represent a substituted or unsubstituted alkyl group, a substituted or unsubstituted aromatic hydrocarbon group, a substituted or unsubstituted aromatic heterocyclic ring Represents a group, Ar ¹
And Ar ² , and Ar ³ and Ar ⁴ may form a ring together. R
¹ , R ² , R ³ , R ⁴ , R ⁵ each independently represent a hydrogen atom, an alkyl group, an alkoxy group, a halogen atom, R ⁶ is a substituted or unsubstituted alkyl group, a substituted or unsubstituted aralkyl group, A substituted or unsubstituted aromatic hydrocarbon group or a substituted or unsubstituted aromatic heterocyclic group, and X represents a hydrogen atom or a halogen atom]. The inventor found that the body solved the problem, and reached the present invention. In the general formula (I), examples of the substituted or unsubstituted alkyl group represented by Ar ¹ , Ar ² , Ar ³ , Ar ⁴ and R ⁶ include a methyl group,
Examples of an ethyl group, a t-butyl group, a cyclohexyl group, a substituted or unsubstituted aromatic hydrocarbon group include a phenyl group,
Tolyl, ethylphenyl, dimethylphenyl, methoxyphenyl, ethoxyphenyl, dimethoxyphenyl, methylmethoxyphenyl, chlorophenyl, bromophenyl, fluorinated phenyl, trifluoromethylphenyl, methylthiophenyl , Naphthyl group, methylnaphthyl group, methylthionaphthyl group, methoxynaphthyl group, ethoxynaphthyl group and other unsubstituted or alkyl group, alkoxy group, alkylthio group, halogen atom-substituted phenyl group, naphthyl group and the like,
Examples of the substituted or unsubstituted aromatic heterocyclic group include a pyridyl group, a quinolyl group, an iso-quinolyl group, a pyrimidyl group,
Coumarinonyl group, thienyl group, thiazolyl group, oxazolyl group, benzothiazolyl group, benzooxazolyl group,
Examples thereof include a 5- or 6-membered ring such as a furyl group, an imidazolyl group, and an oxadiazolyl group and a condensed ring thereof, and alkyl, alkoxy, alkylthio, and halogenated products thereof. Examples of the alkyl group represented by R ¹ , R ² , R ³ , R ⁴ , and R ⁵ include a methyl group, an ethyl group, a t-butyl group, a trifluoromethyl group, a chloromethyl group, a methoxymethyl group, and the like. Examples of the alkoxy group include a methoxy group, an ethoxy group, a trifluoromethoxy group, and a methoxyethoxy group. Examples of the aralkyl group represented by R ⁶ include:
Examples include a benzyl group, a phenethyl group, a methoxybenzyl group, and a methylmethoxybenzyl group. Also, R ¹ , R ² ,
The halogen atom represented by R ³ , R ⁴ , R ⁵ and X includes a fluorine atom, a chlorine atom, a bromine atom and an iodine atom. Preferred specific examples of the diphenylamine-based compound represented by the general formula (I) of the present invention include those having the following structural formulas, but are not limited thereto. The compound represented by the general formula (I) of the present invention can be easily synthesized by a usual method. For example, the following formula (II) [In the formula (II), Ar ¹ , Ar ² , X, R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶
Has the same meaning as in formula (I). An aldehyde compound represented by the following formula (III): [In the formula (III), Ar ³ and Ar ⁴ represent the same meaning as in the formula (I). Can be synthesized by condensing a hydrazine compound represented by the formula: This condensation reaction is generally carried out in an aromatic solvent such as benzene, toluene, xylene, o-dichlorobenzene or an alcohol solvent such as methanol, ethanol, propanol or butanol. If necessary, a catalyst such as potassium acetate, ammonium acetate, p-toluenesulfonic acid, or acetic acid may be used. In addition, N, N-dimethylformamide (DM
The condensation reaction may be performed in an aprotic polar solvent such as F), N-methylpyrrolidone (NMP), N, N'-dimethyl-2-imidazolidinone (DMI). The electrophotographic photoreceptor of the invention has a photosensitive layer containing one or more diphenylamine-based compounds represented by the general formula (I). Various types of photoconductors are known as electrophotographic photoconductors, but the photoconductor of the present invention may be in any of these forms. For example, a charge-generating material and a single-layer photoreceptor having a photosensitive layer formed by dispersing a charge-transporting material in a binder resin or a binder resin, and a charge-generating material mainly composed of a support are provided on a support. There is a so-called laminated photoreceptor in which a charge generation layer is provided and a charge transport layer is provided thereon. Although the diphenylamine-based compound of the present invention is a photoconductive substance, it acts as a charge transporting material and can transport a charge carrier generated by absorbing light extremely efficiently. In order to produce a single-layer photoreceptor, fine particles of a charge generating material may be dispersed in a solution in which a charge transporting material and a resin are dissolved, and this may be coated on a conductive support and dried. In order to fabricate a laminated photoreceptor, a charge generation material is vacuum-deposited on a conductive support, or dissolved in a solvent such as an amine and applied, or the charge generation material needs an appropriate solvent or an appropriate solvent. For example, after a coating solution prepared by dispersing in a solution in which a binder resin is dissolved is applied and dried, a solution containing a charge transport material and a binder resin may be applied thereon and dried. FIGS. 1 and 2 show examples of the constitution of a photoreceptor using the diphenylamine compound of the present invention. FIG. 1 shows a single-layer type photoreceptor in which a photosensitive layer 4 in which a charge generating material 2 and a charge transporting material 3 are mixed with a binder resin is formed on a conductive support 1, and the diphenylamine of the present invention is used as the charge transporting material. System compounds are used. FIG. 2 shows a laminated photoreceptor having a charge generation layer 6 as a photosensitive layer and a charge transport layer 5. The charge transport layer 5 is formed on the surface of the charge generation layer 6. The charge transport layer 5 contains the diphenylamine compound of the present invention. In addition, the charge generation layer 6 and the charge transport layer 5 are reversed, the photosensitive layers 4, 4 'are provided with surface protective layers, and the intermediate layer is provided between the photosensitive layer and the conductive support. There are things. The optimum range of the thickness of the photosensitive layer differs depending on the type of the photoconductor. For example, in the case of the photoreceptor as shown in FIG. 1, it is preferably 3 to 50 μm, more preferably 5 to 30 μm.
m. In the photoreceptor as shown in FIG. 2, the thickness of the charge generation layer 6 is preferably 0.01 to 5 μm, more preferably 0.05 to 2 μm. If the thickness is less than 0.01 μm, the generation of electric charge is not sufficient, and if it exceeds 5 μm, the residual potential is high, which is not practically preferable. The thickness of the charge transport layer 5 is preferably 3 to 50 μm, more preferably 5 μm.
When the thickness is less than 3 μm, the charge amount is insufficient, and when the thickness exceeds 50 μm, the residual potential is high, which is not preferable for practical use. The content of the charge generating material in the photosensitive layer is preferably 50% by weight or less, more preferably 20% by weight or less in the photosensitive layer 4 of the photosensitive member as shown in FIG. The charge transporting material is preferably contained in this layer in an amount of 10 to 95% by weight,
~ 90% by weight is more preferred. In the photoreceptor as shown in FIG. 2, the proportion of the charge generation material in the charge generation layer 6 is at least 30% by weight, more preferably at least 50% by weight. The charge transport layer 5 contains 10 to 95% by weight of a charge transport material,
Preferably, it is contained at 30 to 90% by weight. If the amount of the charge transporting material in this layer is less than 10% by weight, the charge is hardly transported, and if it exceeds 95% by weight, the mechanical strength of the photoconductor is poor, which is not practically preferable. As the binder used in the present invention, polystyrene, polyacryl ad, vinyl polymer such as poly-N-vinyl carbazole or polyamide resin, polyester resin, epoxy resin, phenoxy resin, condensed resin such as polycarbonate resin and the like are used. However, any resin that is insulative and adheres to the support can be used. In the photoreceptor of the present invention, in addition to the binder resin, a halogenated paraffin, polychlorinated biphenyl, dimethylnaphthalene, dibutylphthalate, a plasticizer such as o-terphenyl, chloranil, tetracyanoethylene, 2,4,7-trinitrofluorenone, 5,6-dicyanobenzoquinone, tetracyanoquinodimethane, tetrachlorophthalic anhydride,
Electron-withdrawing sensitizers such as 3,5-dinitrobenzoic acid and other types of sensitizers such as methyl violet, rhodamine B, cyanine dyes, pyrylium salts and thiapyrylium salts may be used. Further, an antioxidant, an ultraviolet absorber, a dispersing aid, an anti-settling agent, and the like may be appropriately used. As the charge generating material, bisazo pigments, triarylmethane dyes, thiazine dyes, oxazine dyes,
Xanthene dyes, cyanine dyes, styryl dyes,
Pyrylium dyes, azo pigments, quinacridone pigments,
Indigo pigments, perylene pigments, polycyclic quinone pigments,
Bisbenzimidazole pigments, indathrone pigments,
Organic substances such as squarium salt pigments, azulene pigments, phthalocyanine pigments, and inorganic substances such as selenium, selenium alloys such as selenium, tellurium, selenium and arsenic, cadmium sulfide, cadmium selenide, zinc oxide, and amorphous silicon. Can be Any other material that absorbs light and generates charge carriers with a very high probability can be used. As the conductive support used in the photoreceptor of the present invention,
Sheets or drums of metals or alloys such as copper, aluminum, silver, iron, zinc, nickel, etc. are used in the form of sheets or drums, or these metals are vacuum-deposited or electroless-plated such as plastic films Alternatively, a layer obtained by applying or depositing a layer of a conductive compound such as a conductive polymer, indium oxide, or tin oxide on a support such as paper or a plastic film is also used. As a material used for the surface protective layer, a polymer such as an acrylic resin, a polyaryl resin, a polycarbonate resin, or a urethane resin as it is, or a material in which a low-resistance compound such as tin oxide or indium oxide is dispersed is suitable. As a material used for the intermediate layer, polyimide, polyamide, nitrocellulose, polyvinyl butyral, a polymer such as polyvinyl alcohol as it is, or a dispersion of a low-resistance compound such as tin oxide or indium oxide, aluminum oxide, zinc oxide, A deposited film of silicon oxide or the like is suitable. The thickness of the intermediate layer is desirably 1 μm or less. Examples Hereinafter, the present invention will be described in more detail with reference to Examples,
This does not limit the embodiments of the present invention. Synthesis Example (Synthesis of Exemplified Compound [2]) Aldehyde compound represented by the following formula 4.05 parts by weight and 1,1-diphenylhydrazine hydrochloride
2.21 parts by weight were put in 200 ml of ethanol, and heated and refluxed with a small amount of acetic acid to cause a reaction. After the reaction, water was poured to precipitate crystals. Thereafter, the precipitate was filtered, washed with n-hexane, and purified by recrystallization with acetonitrile to obtain 4.6 parts by weight of pale yellow crystals of Exemplified Compound [2]. (81% yield). The elemental analysis is as follows. C% H% N% Theoretical 87.49 5.71 6.80 Analytical 87.31 5.79 6.90 Example 1 Bisazo compound represented by the following general formula [A] 0.45 parts of a polyester resin (Vylon 200; manufactured by Toyobo Co., Ltd.) and 0.45 parts of cyclohexanone were dispersed by a sand grinder together with 50 parts. The obtained dispersion of the bisazo compound was applied on a 100-μm-thick aluminized mylar using a film applicator so that the dry film thickness became 0.5 μm, and then dried. A solution prepared by dissolving 70 parts of the exemplified compound [4] and 70 parts of a polycarbonate resin (K-1300; manufactured by Teijin Chemicals Ltd.) in 400 parts of 1,4-dioxane was obtained on the charge generation layer thus obtained. Coating was performed so that the thickness became 16 μm to form a charge transport layer. In this way, 2
An electrophotographic photoreceptor having a photosensitive layer composed of two layers was obtained. Using a commercially available electrostatic copying paper tester (Model EPA-8100, manufactured by Kawaguchi Electric Machinery Co., Ltd.), the obtained photoreceptor was charged by leaving the photoreceptor in a corona at an applied voltage of -6 KV.
Measuring the surface potential V ₀ at that time, then 2 seconds to discharge in the dark, to measure the surface potential V ₂ at this time, followed by a halogen in a state that the surface illuminance of the photosensitive member is 5 lux lamp (color temperature 285
The half-exposure amount E _1/2 (lux · sec) was calculated by measuring the time when the surface potential was reduced to half of V ₂ by irradiating light from 6 ° K).
The surface potential V ₁₂ after 10 seconds of light irradiation, that is, the residual potential was measured. Examples 2 to 4 Exemplified compounds [5], [8], having the same constitution as in Example 1, except that Exemplified compound [4] used in Example 1 was used.

Photoconductors each using [9] were prepared. V ₀ , V ₂ , V ₁₂ , and E _1/2 of the photoreceptor thus obtained were measured in the same manner as in Example 1. Example 5 Bisazo compound represented by the following general formula [B] 0.45 part and 0.45 part of a polystyrene resin (molecular weight: 40,000) were dispersed together with 50 parts of cyclohexanone by a sand grinder. Thick the obtained dispersion liquid of the bisazo compound.
It was applied on a 100 μm aluminized mylar using a film applicator to a dry film thickness of 0.5 μm, and then dried. On the charge generation layer thus obtained, 70 parts of the exemplified compound [10] and a polyarylate resin (U-
A solution prepared by dissolving 70 parts of 100 (manufactured by Unitika) in 400 parts of 1,4-dioxane was applied to a dry film thickness of 16 μm to form a charge transport layer. Thus, an electrophotographic photoreceptor having two photosensitive layers was obtained. Examples 6 to 8 In the same manner as in Example 5, having the same constitution, except that Exemplified compound [1] was used instead of Exemplified compound [10] used in Example 5.
Photoreceptors using [1], [12] and [13] were prepared.
V ₀ , V ₂ , V ₁₂ , and E _1/2 of the photoreceptor thus obtained were measured in the same manner as in Example 1. Example 9 Copper phthalocyanine (50 parts) and tetranitro copper phthalocyanine (0.2 parts) were dissolved in 98% concentrated sulfuric acid (500 parts) with sufficient stirring and dissolved in water (5,000 parts) to prepare a photoconductive material composition of copper phthalocyanine and tetranitro copper phthalocyanine. After the precipitation, the precipitate was filtered, washed with water, and dried at 120 ° C. under reduced pressure. 10 parts of the photoconductive composition thus obtained was mixed with a thermosetting acrylic resin (Acrydik A405; manufactured by Dainippon Ink) 22.5
Parts, melamine resin (Super Beckamine J820; manufactured by Dai Nippon Ink Co., Ltd.) 7.5 parts, 15 parts of the exemplified compound [14] described above,
100 parts of a mixed solvent in which methyl ethyl ketone and xylene were mixed in the same amount was put into a ball mill pot and dispersed for 48 hours to prepare a photosensitive coating solution. The coating solution was applied on an aluminum substrate, and dried to form a photosensitive layer having a thickness of 15 μm. Was formed to produce a photoreceptor. The photosensitive member thus obtained was subjected to corona charging at +6 KV in the same manner as in Example 1, except that V ₀ , V ₂ , V
₁₂ , E _1/2 was measured. Examples 10 to 12 In the same manner as in Example 9, one having the same constitution, except that Exemplified Compounds [1], [2] and [15] were used instead of Exemplified Compound [14] used in Example 9 A photoreceptor to be used was produced. V ₀ , V ₂ , V ₁₂ and E _1/2 of the photoreceptor thus obtained were measured in the same manner as in Example 9. Comparative Examples 1 to 4 In the same manner as in Example 9, but having the same constitution, except that the exemplified compound [14] used in Example 9 was replaced by the following compound [C], [D], [E], [F ], Except that each was used, to produce a photoreceptor. V ₀ , V ₂ , V ₁₂ and E _1/2 of the photoreceptor thus obtained were measured in the same manner as in Example 9. Comparative Examples 5-9 The same hydrazone compounds [G], [H], [I], [I] having the same constitution as in Example 1 except that the exemplified compound [4] used in Example 1 was used. A photoconductor was prepared in the same manner as in Example 1 except that J] and [K] were used. V ₀ , V ₂ , V ₁₂ , and E _1/2 of the photoreceptor thus obtained were measured in the same manner as in Example 1. V _{0 of} the photoreceptors obtained in Examples 1 to 12 and Comparative Examples 1 to 9,
The measurement results of V _2, V _12, E _1/2 are shown in Table 1. As can be seen from Table 1, the photoreceptor of the present invention has a sufficient charge retention ability in both a lamination type and a single layer type, has a small dark decay so as to be sufficiently usable as a photoreceptor, and has an excellent sensitivity. ing. Effects of the Invention The present invention provides a photoconductive compound useful for an electrophotographic photoreceptor. The photoconductive compound of the present invention is particularly useful as a charge transport material. The photoreceptor having the diphenylamine-based compound of the present invention is excellent in photoreceptor characteristics such as sensitivity, charge transport property, initial surface potential, and dark decay rate, and has less light fatigue upon repeated use.

[Brief description of the drawings]

1 and 2 are cross-sectional views showing an example of the configuration of an electrophotographic photosensitive member. In addition, each symbol in FIG. 1 and FIG. 2 is as follows. DESCRIPTION OF SYMBOLS 1 ... Conductive support, 2 ... Charge generating material 3 ... Charge transport material, 4,4 '... Photosensitive layer 5 ... Charge transport layer, 6 ... Charge generating layer

Continuation of the front page (58) Field surveyed (Int. Cl. ⁶ , DB name) C07C 251/86 C07D 215/58 C07D 209/82 C09K 9/02 G03G 5/06 CA (STN)

Claims (2)

(57) [Claims] 1. A compound represented by the following general formula (I) [In the formula (I), Ar ¹ , Ar ² , Ar ³ and Ar ⁴ each independently represent a substituted or unsubstituted alkyl group, a substituted or unsubstituted aromatic hydrocarbon group, a substituted or unsubstituted aromatic heterocyclic ring Represents a group. still,
Ar ¹ and Ar ² or Ar ³ and Ar ⁴ may form a ring together. R ¹ , R ² , R ³ , R ⁴ and R ⁵ each independently represent a hydrogen atom, an alkyl group, an alkoxy group, or a halogen atom, and R ⁶ is a substituted or unsubstituted alkyl group, a substituted or unsubstituted aralkyl group , A substituted or unsubstituted aromatic hydrocarbon group or a substituted or unsubstituted aromatic heterocyclic group, and X represents a hydrogen atom or a halogen atom. 2. An electrophotographic photoconductor containing the diphenylamine compound according to claim 1.