JPH0235981B2 - - 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 an organic photoconductive substance made of a novel hydrazone compound. 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 2,5-bis(P -Diethylaminophenyl)-1,3,4-oxadiazole and other low-molecular organic photoconductive substances are known. As a result of research on low-molecular organic photoconductive materials, the present inventor found that by selecting an appropriate binder resin, it is possible to form a photosensitive layer in the form of a film with good film properties. , general formula (1) (R ₁ and R ₂ are lower alkyl group, lower alkoxy group, di-lower alkylamino group, A is methyl, phenyl,

[Formula]. Further, R ₃ is a lower alkyl group or a lower alkoxy group. The inventors have discovered that a photoreceptor extremely useful in electrophotography can be obtained by incorporating the compound represented by ) into the photosensitive layer, and have arrived at the present invention. The hydrazone compound represented by the general formula (1) has the general formula
(a) (wherein R ₁ and R ₂ have the same meanings as before) and the general formula (b) (wherein A has the same meanings as before). It can be easily synthesized by adding a hydrazone compound represented by the formula at a molar ratio of 1:1 and heating and refluxing the mixture in a suitable solvent (for example, ethanol). In particular, R ₁ and R ₂ were smaller than three times the Van der Waals radius of the benzene ring, and methyl and ethyl groups had particularly good electrophotographic properties. This is considered to be because the hydrazone compound does not act as a major inhibiting factor for the layered structure. 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 compound, and preferable types include (1) electron-donating A charge transfer complex formed by a combination of a magnetic substance and an electron-accepting substance. (2) Organic photoconductors sensitized by adding dyes and acidic compounds. (3) Pigment dispersed in a hole matrix.
(4) Functionally separated charge generation layer and charge transfer layer.
(5) Those whose main components are a eutectic complex of dye and resin and an organic photoconductor. (6) There are charge transfer substances containing organic or inorganic charge generating materials. Among these, types (3) to (6) are preferred. moreover
In the case of a photoconductor of type (4), a hydrazone compound represented by general formula (1) is used as a charge transfer material for the charge transfer layer of the photoconductor, which is functionally separated into two layers: a charge generation layer and a charge transfer layer. When used, the sensitivity of the photoreceptor is particularly improved and the residual potential is low. In addition, in this case, during repeated use,
A decrease in charging voltage, a decrease in sensitivity, and an increase in residual potential can also be suppressed to a practically negligible level. Therefore, the photoreceptor of type (4) will be explained. The layer structure requires a conductive layer, a charge generation layer, and a charge transfer layer, and the charge generation layer may be placed either above or below the charge transfer layer, but in an electrophotographic photoreceptor of the type that is used repeatedly, It is preferable to laminate a conductive layer, a charge generation layer, and a charge transfer layer in this order mainly from the viewpoint of mechanical strength of the surface of the photoreceptor and also from the viewpoint of chargeability. If necessary, it becomes necessary to provide an adhesive layer between the conductive layer and the charge generation layer for the purpose of improving adhesiveness. As the conductive layer, ion conductive quaternary ammonium salt,
Alternatively, organic compounds having ammonium sulfonate salts are also effective, but aluminum, which is generally electronically conductive, is inexpensive and has good conductivity. However, either type of compound can be used. As the material used for the adhesive layer, various conventionally used binders such as casein are used. The thinner the adhesive layer is, the better, but it is usually 0.1μ or more.
1.0μ is appropriate. 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 and selenium.
Tellurium, selenium-arsenic, selenium-tellurium-arsenic,
Inorganic substances such as amorphous silicon, thiopyrylium dyes, pyryllium dyes, triphenylmethane dyes, thiazine dyes, cyanine dyes, polymethine dyes, phthalocyanine pigments, perylene pigments, azo pigments, and quinophthalone pigments. , dioxazine pigments, quinacridone pigments, perinone pigments, threne pigments, indigo pigments, thioindigo pigments, and polycyclic quinone pigments. The charge generation layer is provided by means such as vacuum evaporation, sputtering or coating, depending on the type of charge generation substance used. When coating, the charge generating material may be provided binder-free, as a resin dispersion, or as a homogeneous solution of the binder and the charge generating material. When the charge generation layer is formed by applying a resin dispersion or solution of the charge generation material, a large amount of binder used will affect the sensitivity, so the proportion of the binder in the charge generation layer should be 80% or less, preferably 40%.
The following are desirable. The binder used in the charge generation layer includes various conventionally used resins such as polycarbonate, polyester, polyvinyl butyral, and copolymer nylon. Although the film thickness is not constant depending on the charge generating material used, a thin film thickness of 1 μm or less is preferable overall. A charge transport layer is provided on the charge generation layer provided by any of the above methods. The charge transfer layer has a relatively thick film thickness from the viewpoint of potential retention, and preferably has a thickness of 5 to 30 .mu.m, preferably 7 to 18 .mu.m. The hydrazone compound used in the present invention itself has poor film-forming ability, and a charge transfer layer is formed by coating and drying a solution dissolved in a suitable organic solvent together with various binder resins using a method such as a wire bar. Examples of the hydrazone compound used in the present invention include the following compounds. Furthermore, as the binder resin, acrylic resin, methacrylic resin, vinyl acetate resin, styrene resin, polyphenylene oxide resin, noryl resin, vinyl chloride resin, arylate resin, diallyl phthalate resin, and polycarbonate resin may be used. Can be done. Among these, photoreceptors using arylate resins have particularly good dimensional stability, toner filming properties,
It had excellent weather resistance and heat resistance. The hydrazone compound used in the present invention has effective mobility for both holes and electrons, but holes tend to have slightly better charge transfer efficiency. For example, in the case of hole transfer, it is necessary to charge the surface of the charge transfer layer negatively, and when exposed to light, holes, which are mainly formed in the charge generation layer, are injected into the charge transfer layer, and then reach the surface and become negatively charged. Neutralization of charges causes attenuation of surface potential, creating electrostatic contrast with unexposed areas. Various conventional developing methods can be used to visualize the image. For photoreceptors other than type (4), conventional developing methods proposed so far can be similarly used. The electrophotographic photoreceptor of the present invention can be used not only for dry transfer copying machines, but also for laser printers,
CRT printer, light emitting diode printer,
It can also be widely used in electrophotographic application fields such as electrophotographic plate making systems. Next, a synthesis example of the hydrazone compound used in the present invention will be shown. Synthesis Example (Exemplary Compound 10) N,N-di(4-benzyl)amino-m-toluidine (melting point 57-58.5°C) was subjected to formyl reaction by Vils-Meyer reaction to synthesize a compound having the following structure. Ethanol was used as the recrystallization solvent. Melting point 108~110℃ Mass spectrometry value: M/l=344 When this compound and N,N-diphenylhydrazine are heated under reflux in equimolar ethanol for about 2 hours, a yellow-white powder is precipitated over the entire surface. When this is taken and further recrystallized with ethanol, the desired hydrazone compound is obtained with a yield of approximately 90 to 96%. Melting point: 146.0-147.5°C Other hydrazone compounds can also be easily synthesized according to the above synthesis example. Next, an electrophotographic photoreceptor using the hydrazone compound of the present invention will be specifically described based on the following examples. Example 1 A polyvinyl alcohol aqueous solution was applied onto a 100μ thick aluminum laminated film, dried, and the coating amount was
An adhesive layer of 0.8 g/m ² was formed. Next, a bisazo pigment having the following structure was dissolved in n-butylamine and applied onto the adhesive layer, with a coating amount of 0.20 g/m ² after drying. Next, 2 g of hydrazone compound of Exemplary Compound 10 and 2.5 g of polyarylate resin (manufactured by Unitika, U-100)
g was dissolved in 30 ml of chlorobenzene, and this was applied in a layered manner onto the azo pigment layer. The coating amount of the hydrazone-containing layer at this time was 10 g/m ² . The electrophotographic photoreceptor thus prepared was corona charged at 6.0 KV using an electrostatic copying paper tester SP-428 manufactured by Kawaguchi Electric Co., Ltd., and then placed in a dark place for 10 minutes.
After being held for a second, it was exposed to light at an illuminance of 51 ux and the charging characteristics were investigated. For comparison, a hydrazone compound in which R ₁ and R ₂ are substituted with chlor, which is an electron-accepting group, and A is a phenyl group, and a hydrazone compound in which R ₁ is substituted with chlor, and A is a phenyl group, are replaced with Exemplary Compound 10. An electrophotographic photoreceptor was produced in the same manner as above. These were used as Comparative Examples 1 and 2 and their electrophotographic properties were examined in the same manner. Hydrazone compound used in Comparative Example 1 Hydrazone compound used in Comparative Example 2 The initial potential is Vo (volt), the potential retention rate for 10 seconds in the dark is Rv (%), and the amount of exposure required to reduce the initial potential to half is E1/2 (lux・sec).
The electrophotographic characteristics of various types of photoreceptors were investigated, and the results are shown in Table 1 below.

[Table] From the above table, it can be seen that the influence of the R ₁ R ₂ substituent on the sensitivity E1/2 is large, and the hydrazone compound of the present invention substituted with an electron-donating group is greatly superior. Examples 2 to 6 Electrophotographic photoreceptors were prepared in exactly the same manner as in Example 1, except that each hydrazone compound shown in Table 2 below was used in place of the hydrazone compound used in Example 1. Furthermore, the electrophotographic characteristics of each of these photoreceptors were measured in the same manner as in Example 1. These results are shown in Table 2.

[Table] Example 7 Copper-phthalocyanine pigment prepared for electrophotography (Rioconductor ERPC manufactured by Toyo Ink Co., Ltd.) 1
g and polyarylate resin (Unitika U-
100) 1 g was added to 100 g of dichloroethane, dispersed with a sand grinder, and then applied to the aluminum surface of an aluminum foil laminated polyester film so that the coating amount after drying was 0.1 g/m ² to form a charge generation layer. . On this charge generation layer, 2 g of the hydrazone compound of Exemplary Compound 7, 2 g of polyphenylene oxide (PPO, manufactured by GE), and 1.5 g of polyarylate resin (U-100, manufactured by Unitika) were dissolved in 20 g of monochlorobenzene. Coating was carried out to form a charge transfer layer with a film thickness of 12 g/m ² . The characteristics of the electrophotographic photoreceptor thus obtained were as follows. Vo=1010 (volt) Rv=78 (%) E1/2=2.5 (lux・sec) Example 8 The 780 nm spectral sensitivity of the photoreceptor obtained in Example 7 was measured with a monochromator E1/2= 5.0 (erg/cm ² ), the photoreceptor was excellent as a photoreceptor for semiconductor lasers. Example 9 Copper-phthalocyanine pigment (Lioconductor
ERPC), 4 g of polyarylate resin, and 3.5 g of hydrazine compound of Exemplary Compound 10 were added to 30 g of tetrahydrofuran, and thoroughly milled using a ball mill. The resulting solution was a viscous, bluish solution in which the phthalocyanine pigment was dispersed.
Example 1 This solution was prepared using a doctor blade method.
A single-layer type photoreceptor with a coating weight of 8.0 g/m ² was prepared by coating it on the aluminum laminated film used in . The characteristics of the electrophotographic photoreceptor thus obtained were as follows. Applied voltage 6.0KV Vo=870 (volt) Rv=88 (%) E1/2=7.5 (lux・sec) Furthermore, the spectral sensitivity at 780nm is E1/2=18
(erg/cm ² ) The spectral sensitivity at 670 nm was E1/2=9 (erg/m ² ). Example 10 Alcohol-soluble nylon (Toyo Rayon Co., Ltd.) was coated on a 90μ thick aluminum-deposited polyester film.
CM-8000) 1g and polymethine dye with the following structure
0.15 g was dissolved in 40 g of ethanol, and a charge generation layer having a thickness of 0.2 g/m ² after drying was prepared by the doctor blade method. On this charge generation layer, 1 g of the hydrazine compound of Exemplary Compound 14 was applied by dissolving 1 g of vinyl acetate:vinyl chloride copolymer in 10 g of butyl acetate to prepare a charge transport layer having a thickness of 8 g/m ² . The E1/2 of the photoreceptor thus obtained was 3.5 lux·sec (white light source). Also, the spectral sensitivity (E1/2) of this photoreceptor at 820nm is
5.0erg/cm ² , making it an excellent photoreceptor for semiconductor lasers. Example 11 Regarding the repetition characteristics of each photoreceptor of Examples 1 to 7 and 9 - 6.0KV corona charging, immediately remove static electricity by irradiating 400lux white light for 1 second, and repeat the same process 500 times, with this as one cycle. The degree of attenuation of the initial potential Vo was investigated. The results are shown in Table 3.

【table】

[Table] There is also a tendency for the E1/2 of each photoreceptor to improve,
No decrease phenomenon was observed. These results reveal that the photoreceptor using the hydrazone compound of the present invention exhibits no deterioration phenomena due to corona charging or light irradiation, and at the same time can sufficiently withstand continuous use.

Claims (1)

[Scope of Claims] 1. An electrophotographic photoreceptor comprising a photosensitive layer containing a hydrazone compound represented by the following general formula () on a conductive support. (R ₁ and R ₂ are a lower alkyl group, a lower alkoxy group, or a di-lower alkylamino group, and A is methyl, phenyl, or [Formula]. Furthermore, R ₃ is a lower alkyl group or a lower alkoxy group.) 2. The electrophotographic photoreceptor according to claim 1, wherein the photosensitive layer contains a carrier transfer substance and a carrier generation substance, and the carrier transfer substance is a hydrazone compound represented by the general formula (). 3. The electrophotographic photoreceptor according to claim 1, wherein R ₁ and R ₂ are a methyl group or an ethyl group. 4. The electrophotographic photoreceptor according to claim 1, wherein a polyarylate resin is used as the binder resin. 5. The electrophotographic photoreceptor according to claim 2, wherein the carrier generating substance is copper-phthalocyanine.