JPH0247741B2 - DENSHISHASHINYOKANKOTAI - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a photoreceptor for electrophotography. Specifically, the present invention relates to an electrophotographic photoreceptor having a photosensitive layer containing a specific hydrazone compound on a conductive support. Conventionally, inorganic photoconductive substances such as selenium, cadmium sulfide, and zinc oxide have been widely used in the photosensitive layer of electrophotographic photoreceptors. In recent years, research on organic photoconductive materials has progressed, and some have been put into practical use as electrophotographic photoreceptors. Organic photoconductive materials have advantages over inorganic materials in that they are lighter in weight, easier to form into films, and easier to manufacture photoreceptors. Many studies have been conducted on photoconductive polymers such as polyvinyl cabazole as organic photoconductive materials, but these polymers alone have poor film properties, flexibility, and adhesion, and it is difficult to overcome these drawbacks. Plasticizers, binders, etc. are added to improve this, but this tends to cause other problems such as a decrease in sensitivity and an increase in residual potential, making it extremely difficult to put it into practical use. On the other hand, with organic low-molecular photoconductive compounds, if a polymer with excellent film properties, flexibility, and adhesive properties is selected as a binder, it is possible to easily obtain a photoreceptor with excellent mechanical properties. It has been difficult to find compounds suitable for making sensitive photoreceptors. Therefore, the present inventors conducted intensive research on organic low-molecular photoconductive compounds that provide electrophotographic photoreceptors with high sensitivity and high durability, and found that a specific hydrazone compound is suitable. reached. That is, the gist of the present invention is the general formula () (In the formula,

[Formula] represents a hydrocarbon cyclic group that may have a substituent, and R ₁ and R ₂ are each independently selected from the group consisting of a hydrogen atom, a hydrocarbon group that may have a substituent, and a heterocyclic group. It represents a selected group, and R ₁ and R ₂ may be taken together to form a ring. ) An electrophotographic photoreceptor characterized by having a photosensitive layer containing a hydrazone compound represented by the following. In the above general formula ()

[Formula] is an example For example

【formula】 【formula】

【formula】

【formula】 【formula】

[Formula] etc. divalent hydrocarbon ring residue;

【formula】

Represents a divalent fused aromatic hydrocarbon ring residue such as [Formula]. R ₁ and R ₂ are, for example, a hydrogen atom; an alkyl group such as a methoxy group or an ethyl group; an aromatic hydrocarbon group derived from benzene, naphthalene, anthracene, pyrene, acenaphthene, fluorene, etc.; pyridine, pyrrole, pyrazole, dibenzofuran represents an aromatic heterocyclic group derived from , carbazole, etc., and R ₁ and R ₂ may be combined with each other to form a ring. Said

[Formula] R ₁ and R ₂ each may have a substituent, and examples of the substituent include an alkyl group such as a methyl group and an ethyl group; an alkylene group such as a methylene group and an ethylene group; a chlorine atom, a bromine atom Halogen atoms such as; alkoxy groups such as methoxy groups and ethoxy groups; aryloxy groups such as phenoxy groups; amino groups such as dimethylamino groups, diethylamino groups, phenylamino groups, and aminophenylamino groups; methylthio groups, ethylthio groups, etc. alkylthio group; nitro group; alkyl ester group such as methyl ester group, ethyl ester group; amide group such as phenylamide group, dimethoxyphenylamide group, chlorophenylamide group; hydroxyl group; oxo group; phenyl group, methoxyphenyl group , methylphenyl group, dinitrophenyl group, and other aromatic hydrocarbon groups; and aromatic heterocyclic groups such as benzimidazolyl group. The hydrazone compound of the general formula () described in the present invention can be produced by a known method. For example, the expression

Ketone represented by [formula] compounds and formulas

It can be obtained by reacting a hydrazine compound represented by the formula in ethyl alcohol in the presence of a catalytic amount of acetic anhydride at reflux temperature. Specific compounds corresponding to the general formula () are listed in Table 1. The electrophotographic photoreceptor of the present invention has the general formula ()
It has a photosensitive layer containing one or more hydrazone compounds represented by: There are various forms of the photosensitive layer of the electrophotographic photoreceptor, and the photosensitive layer of the electrophotographic photoreceptor of the present invention may be any of them. As examples, the photoreceptors shown in FIGS. 1 to 4 are shown. The photoreceptor shown in FIG. 1 has a conductive support 1 provided with a photosensitive layer 2 comprising a hydrazone compound 2a, a binder 2b, and a sensitizing dye or an electron-withdrawing compound added as necessary. The photoreceptor shown in FIG. 2 has a photosensitive layer 2' provided on a conductive support 1, in which a charge carrier generating substance 3 is dispersed in a charge transfer medium 4 consisting of a hydrazone compound 2a and a binder 2b. The photoreceptor shown in FIG. 3 has a photosensitive layer 2'' consisting of a charge carrier generation layer 5 and a charge transfer layer 6 on a conductive support 1, and the layer 5 is composed of a charge carrier generation substance 3 and a binder 2b. The layer 6 is composed of a hydrazone compound 2a and a binder.The photoreceptor shown in FIG. 2″,
Layer 7 is a deposited film of charge carrier generating substance 3. In the photoreceptor shown in Figure 1, hydrazone compound 2
a acts as a photoconductive substance, and the generation and transfer of charge carriers necessary for photoattenuation are carried out by the hydrazone compound 2
This is done via a. Many hydrazone compounds 2
Since the absorption of a is in the low wavelength range from ultraviolet to visible range,
In order to form an image with visible light, it is necessary to add a sensitizing dye that absorbs in the visible region or to add an electron-withdrawing compound to form a charge transfer complex and sensitize it. In the photoreceptor shown in FIGS. 2 to 4, the charge carrier generating substance 3 generates charge carriers by exposure to light, and the charge carriers are generated by the charge transport medium 4 or the charge transport layer 6 (mainly in which the hydrazone compound 2a of the present invention acts). A move is made. The photoreceptor shown in Fig. 1 is prepared by dissolving a hydrazone compound 2a together with a binder 2b in a solvent, adding a sensitizing dye or an electron-withdrawing compound if necessary, coating it on a conductive support 1, and drying it. Ru. The photoreceptor shown in FIG. 2 is produced by dispersing fine particles of charge carrier generating substance 3 in a solution containing a hydrazone compound 2a and a binder 2b, coating the dispersed particles on a conductive support 1, and drying the dispersed particles.
The photoreceptor shown in FIG. 3 is prepared by coating a conductive support 1 with a dispersion obtained by dispersing fine particles of a charge carrier generating substance 3 in a solvent in which a binder 2b is dissolved, and drying the dispersion. and binder 2b
It is made by applying a solution containing and drying it. The photoreceptor shown in FIG. 4 is produced by providing a vapor-deposited film of a charge carrier generating substance 3 on a conductive support 1, applying a solution containing a hydrazone 2a and a binder 2b thereon, and drying. For application, a roll coater, wire bar, doctor blade, etc. are usually used. The thickness of the photosensitive layer is as shown in FIGS. 1 and 2.
It is 3-50μ, preferably 5-20μ. Also the third
In the case of the figure, the thickness of the charge carrier generation layer is 0.5 to 5μ,
The thickness of the charge transfer layer is preferably 3 to 50 microns, preferably 5 to 20 microns. Also the first
In the photoreceptor shown in the figure, the proportion of the hydrazone compound in the photosensitive layer is 10 to 70% by weight, preferably 30 to 50% by weight, based on the photosensitive layer. Furthermore, the sensitizing dye used to impart photosensitivity in the visible region is 0.1 to 5% by weight, preferably 0.5 to 3% by weight, based on the photosensitive layer.
It is. The electron-withdrawing compound is added in an amount of 0.1 to 50% by weight, preferably 5 to 30% by weight, based on the photosensitive layer. In the photoreceptor shown in Figure 2, the proportion of the hydrazone compound in the photosensitive layer is 10 to 90% by weight, preferably 10% by weight.
60% by weight, and the proportion of charge carrier generating material is 1 to 50% by weight, preferably 3 to 20% by weight. The proportion of the hydrazone compound in the charge transfer layer in the photoreceptor of FIG. 3 is 10 to 95% by weight, preferably
It is 10-60% by weight. In addition, in producing any of the photoreceptors shown in FIGS. 1 to 3, a plasticizer and a sensitizer can be used together with a binder. As the conductive support of the photoreceptor of the present invention, for example, a metal plate or foil made of aluminum or the like, a plastic film on which a metal such as aluminum is vapor-deposited, or paper subjected to conductive treatment is used. As binders, vinyl polymers such as polystyrene, polyacrylamide, and poly-N-vinylcarbazole, and condensation resins such as polyamide resins, polyester resins, epoxy resins, phenoxy resins, and polycarbonate resins are used. Any resin that is adhesive to the body can be used. As the sensitizing dye, electron-withdrawing compound, and charge carrier generating substance used in the photosensitive layer, well-known ones can be used. Examples of the sensitizing dye include triphenylmethane dyes such as methyl violet, brilliant green, and crystal violet, thiazine dyes such as methylene blue, cyanine dyes, and pyrylium dyes. Examples of electron-withdrawing compounds include quinones such as chloranil, 1-nitroanthraquinone, and 2-chloroanthraquinone; aldehydes such as 2-chlorobenzaldehyde and 4-nitrobenzaldehyde; 3,5-dinitrobenzophenone;
4,7-trinitrofluorenone, 2,4,5,
Examples include ketones such as 7-tetranitrofluorenone, acid anhydrides such as phthalic anhydride, and cyano compounds. Charge carrier generating substances include selenium, selenium-tellurium alloys, selenium-arsenic alloys, inorganic photoconductive substances such as cadmium sulfide, copper phthalocyanine, azo pigments, disazo pigments, trisazo pigments, cyanine pigments, and anthraquinone pigments. Examples include organic photoconductive substances such as pigments, perylene pigments, anthraquinone pigments, pyrylium salts, thioindigo, and quinacridone. Furthermore, a well-known plasticizer may be contained in order to improve the film formability, flexibility, and mechanical strength of the photoreceptor.
Examples of plasticizers include aromatic compounds such as phthalic esters, phosphoric esters, halogenated paraffins, and methylnaphthalene. The photoreceptor obtained as described above can be provided with an adhesive layer or a barrier layer, as required, between the conductive support and the photosensitive layer. Materials for these layers include polyamide, nitrocellulose, aluminum oxide, etc., and the film thickness is preferably 1 μm or less. The photoreceptor of the present invention has excellent advantages such as very high sensitivity, small accumulation of residual potential and small fluctuations in surface potential and sensitivity due to repeated use, excellent durability, and high flexibility. Examples are shown below. In the following examples, all parts are by weight. Example 1 2,6-(diphenyl)-4-(4-dimethylaminophenyl)-pyrylium fluoroborate 2-part phenoxy resin (trade name "PKHH",
(manufactured by UNION CARBIDE) 1 part dioxane 97 parts The above components were ground and mixed in a ball mill to obtain a charge carrier generating substance dispersion. This was applied with a wire bar onto a polyester film on which aluminum was deposited and dried to form a charge carrier generation layer with a thickness of 1 μm. On this charge carrier generation layer, 10 parts of a hydrazone compound of structural formula No. 10 shown in Table 1 and 10 parts of polycarbonate resin (trade name "Panlite L", manufactured by Teijin) were dissolved in 80 parts of tetrahydrofuran. A charge transfer layer was formed by applying the coating liquid to a thickness of 15 μm after drying, and photoreceptor No. 1 was prepared. Using an electrostatic copying paper tester (trade name "SP428" manufactured by Kawaguchi Electric Seisakusho Co., Ltd.), the photoreceptor was first charged in a dark place by -6kV corona discharge, then exposed to white light, and the surface Time (seconds) until the potential decreases to half of the initial surface potential
was determined, and the photosensitivity E1/2 lux seconds was determined. The sensitivity of this photoreceptor was E1/2 = 4 lux seconds. Example 2 β-type copper phthalocyanine 2 parts Phenoxy resin (PKHH) 1 part Dioxane 97 parts The above components were ground and mixed in a ball mill to obtain a charge carrier generating substance dispersion. This was applied with a wire bar onto a polyester film on which aluminum was deposited and dried to form a charge carrier generation layer with a thickness of 1 μm. A coating solution prepared by dissolving 10 parts of the hydrazone compound of structural formula No. 10 shown in Table 1 and 10 parts of polycarbonate resin ("Panlite L") in 80 parts of tetrahydrofuran was applied onto this charge carrier generation layer, and then the film was dried. A charge transfer layer was formed by coating to a thickness of 15 μm, and photoreceptor No. 2 was prepared. The sensitivity of this photoreceptor was measured in the same manner as in Example 1 and found to be E1/2.
= 4.4 lux seconds. Example 3 Perylene pigment (trade name “NOVOPERM”)
RED BL (manufactured by Hoechst) 2 parts phenoxy resin (PKHH) 1 part dioxane 97 parts The above components were ground and mixed in a ball mill to obtain a charge carrier generating substance dispersion. This was applied with a wire bar onto a polyester film on which aluminum was deposited and dried to form a charge carrier generation layer with a thickness of 1 μm. On this charge carrier generation layer, 10 parts of a hydrazone compound of structural formula No. 10 shown in Table 1 and 10 parts of polycarbonate resin (trade name "Panlite L", manufactured by Daijin Co., Ltd.) were dissolved in 80 parts of tetrahydrofuran. The coating liquid was coated to a dry thickness of 15 μm and dried to form a charge transfer layer, thereby producing photoreceptor No. 3. The sensitivity of this photoreceptor was measured in the same manner as in Example 1 and found to be E1/2 = 8 lux seconds. Examples 4 to 5 In Example 1, except that the hydrazone compounds of Structural Formulas No. 6 and No. 8 of Table 1 were used instead of the hydrazone compound of Structural Formula No. 10 of Table 1 as charge transfer substances. Similarly, photoreceptors No. 4 and No. 5
was created. When the sensitivity was measured in the same manner as in Example 1, E1/2 was 5 lux seconds for photoreceptor No. 4, and E1/2 was 6.8 lux seconds for photoreceptor No. 5. Examples 6 to 7 The hydrazone compounds of Structural Formula No. 6 and No. 8 of Table 1 were used instead of the hydrazone compound of Structural Formula No. 10 of Table 1 as the charge transfer substance in Example 2. Photoreceptors No. 6 and No. 7 were produced in the same manner. When the sensitivity was measured in the same manner as in Example 1, E1/2 = 8 lux seconds for photoreceptor No. 6,
For photoreceptor No. 7, E1/2 was 6.8 lux seconds. Examples 8 to 9 The hydrazone compounds of Structural Formula No. 6 and No. 8 of Table 1 were used instead of the hydrazone compound of Structural Formula No. 10 of Table 1 as the charge transfer substance in Example 3. Photoreceptors No. 8 and No. 9 were produced in the same manner. When the sensitivity was measured in the same manner as in Example 1, E1/2 = 14 lux seconds for photoreceptor No. 8,
For photoreceptor No. 9, E1/2 was 16 lux seconds. Example 10 Hydrazone compound of structural formula No. 10 in Table 1 1 part 2,6-(diphenyl)-4-(4-dimethylaminophenyl)-pyrylium fluoroborate 1 part polycarbonate resin (trade name "Panlite") 1 part dioxane 22 parts The above components were ground and mixed in a ball mill to obtain a dispersion. This is applied with a wire bar onto a polyester film coated with aluminum, dried,
A photosensitive layer with a thickness of 30 μm was formed. When the sensitivity of this photosensitive plate was measured in the same manner as in Example 1, it was found that E
1/2 = 5.2 lux seconds.

[Brief explanation of drawings]

FIG. 1 is a partial cross-sectional view showing the configuration of the electrophotographic photoreceptor of the present invention, and FIGS. 2, 3, and 4 are partial cross-sectional views showing other configurations of the electrophotographic photoreceptor of the present invention, respectively. . DESCRIPTION OF SYMBOLS 1... Conductive support, 2, 2', 2'', 2... Photosensitive layer, 2a... Hydrazone compound, 2b... Binder, 3... Charge carrier generating substance, 4... Charge transport medium,
5, 7... Charge carrier generation layer, 6... Charge transfer layer.

Claims (1)

[Scope of Claims] 1. A photoreceptor for electrophotography, characterized in that the photosensitive layer contains a hydrazone compound represented by the following general formula (). (In the formula, [Formula] represents a hydrocarbon ring group that may have a substituent, and R ₁ and R ₂ each independently represent a hydrogen atom, a hydrocarbon group that may have a substituent, and a heterocyclic group that may have a substituent.) (Represents a group selected from the group consisting of ring groups, and R ₁ and R ₂ may be combined with each other to form a ring.)