JPH0314338B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an electrophotographic photoreceptor, and more specifically, the present invention relates to an electrophotographic photoreceptor, and more specifically, an electrophotographic photoreceptor containing a hydrazone compound represented by the following general formula () or () in a photosensitive layer formed on a conductive support. It's about the body. (In the formula, R ₁ is an alkyl group, allyl group, propenyl group, phenyl group, benzyl group, R ₂ is hydrogen, alkyl group, halogen, alkoxy group, R ₃ is hydrogen,
Alkyl group, R ₄ is hydrogen, halogen, alkyl group,
Represents an alkoxy group. ) Conventionally, in electrophotographic technology, inorganic materials such as selenium, cadmium sulfide, amorphous silicon, and zinc oxide have been widely used in the photosensitive layer of electrophotographic photoreceptors, but in recent years organic photoconductive materials have been used. Many studies have been conducted on the use of electrophotographic photoreceptors. Here, the basic properties required for an electrophotographic photoreceptor are (1) High chargeability due to corona discharge in the dark. (2) The resulting corona charge has little attenuation in the dark. (3) Charge is quickly dissipated by light irradiation. (4) There is little residual charge after irradiation with light. etc. Selenium, a conventional inorganic material electrophotographic photoreceptor,
Cadmium sulfide and other materials meet the requirements for photoreceptors in terms of basic properties, but there are manufacturing problems such as high toxicity, difficulty in film formation, lack of flexibility, and high manufacturing costs. However, in the future, the use of inorganic substances will be more expensive, and in the future, the use of inorganic substances will be limited due to the depletion of resources. The use of photoreceptors of materials is desired. However, in view of these points, research on electrophotographic photoconductors made of organic materials has been actively conducted in recent years, and electrophotographic photoreceptors using various organic materials have been proposed and put into practical use. There is also. Generally speaking, organic materials have better transparency than inorganic materials, are lighter in weight, and are easier to form into films.
It has both positive and negative chargeability, and has advantages such as easy manufacture of photoreceptors. By the way, typical organic electrophotographic photoreceptors that have been proposed so far include polyvinyl carbazole and its derivatives, but these do not necessarily have sufficient film properties, flexibility, solubility, adhesive properties, etc. In addition, polyvinylcarbazole is sensitized with biryllium salt dye (Special Publication No. 1973-
25658) and polyvinylcarbazole and 2,4,7
- Although there are improved products such as those sensitized with trinitrofluorenone (U.S. Patent No. 3,484,237), they still satisfy the basic properties, mechanical strength, and high durability requirements of photoreceptors as listed above. I still don't get enough of what I want. As a result of research into photoconductive substances with high sensitivity and high durability, the present inventors found that the hydrazone compound represented by the above general formula () or general formula () is effective, and the present invention It came to this. The hydrazone compound of general formula () or general formula () according to the present invention is usually synthesized by the following synthesis process. That is, benzaldehyde represented by general formula (a) or a phenyl ketone derivative and a phenylhydrazine derivative represented by general formula (b) are mixed in a suitable solvent (e.g. alcohol) using sodium acetate (potash) or caustic soda (potash) as a catalyst. The mixture is heated under reflux to synthesize a hydrazone compound represented by general formula (c). Reaction formula; The thus obtained hydrazone compound (c) is heated between 50 and 150°C with an aryl halide represented by the general formula (d) or a propynyl halide represented by the general formula (e) using an alkali as a catalyst. The hydrazone compound of the present invention can be easily obtained by heating and stirring. CH ₂ ＝ _CH − _CH 2 This is usually carried out using aqueous dimethyl sulfoxide. Alternatively, hydrous dimethylformamide may be used.
Among these hydrazone compounds represented by the general formula () or (), electrophotographic properties,
The following compounds were effective in terms of solubility in organic solvents, stability against light and heat, economic efficiency, ease of synthesis, etc. These compounds are only the best among the hydrazone compounds of the present invention, and it goes without saying that the present invention is not limited thereto. Next, synthetic examples of some of these hydrazone compounds will be described. Synthesis Example 1 (Synthesis of Exemplified Compound No. 6) 5.4 g of diethylaminobenzaldehyde-N-phenylhydrazone and 4.8 g of aryl bromide obtained by reacting equimolar amounts of N,N-diethylbenzaldehyde and phenylhydrazine in ethanol.
g was added to 5 c.c. of 5N caustic soda and 20 c.c. of dimethyl sulfoxide, and the mixture was stirred at room temperature for 2 hours.
After the reaction is complete, 50 c.c. of water is added and the precipitated solid is taken out and then washed with water. Recrystallization was performed from 50 c.c. of methanol to obtain 4.5 g of slightly yellowish needle-shaped crystals. The melting point of this compound is IR at 103.5-105.0℃
(KBr tablet), the absorption of -NH- at 3300 cm ^-1 disappeared. Synthesis Example 2 (Synthesis of Exemplified Compound No. 13) In the same manner as in Synthesis Example 1, 7.6 g of N,N-dibenzylaminobenzaldehyde-N-phenylhydrazone (melting point 186.0-188.0°C) and allyl bromide were added.
Add 4.8 g to 5 c.c. of 5N caustic soda and 30 c.c. of dimethyl sulfoxide, and stir at room temperature for 2 hours.
After the reaction is completed, 50 c.c. of water is added and the precipitated solid is taken out and then washed with water. Recrystallize from 240 c.c. of ethanol to obtain 7.2 g of pale yellow-white needle-shaped crystals.
IR (KBr tablet) at melting point of this compound 115℃~117℃
Therefore, the -NH- absorption at 3300 cm ^-1 disappeared. Synthesis Example 3 (Exemplary Compound 20) N,N-diarylaminobenzaldehyde and phenylhydrazine were added to methanol in an amount of 1.2 times the number of moles of phenylhydrazine relative to the aldehyde, and heated under reflux for about 2 hours to obtain diarylaminobenzaldehyde. Ruaminobenzaldehyde-N-phenylhydrazone (melting point 63.5-65.0°C) is obtained. 5.0 g of the obtained hydrazone and 4.8 g of aryl bromide were added to 5 c.c. of 5N caustic soda and 20 c.c. of dimethyl sulfoxide and stirred at room temperature for 2 hours. After the reaction is complete, water
50 c.c. and ethyl acetate were added to extract the organic layer, ethyl acetate, etc. were distilled off, and the residue was recrystallized from 150 c.c. of alcohol to obtain 3.8 g of pale yellow-white crystals. Melting point: 38.5 to 40.0° C. The electrophotographic photoreceptor according to the present invention is obtained by containing one or more of the compounds shown above, and has extremely excellent performance. Also, other hydrazone compounds (e.g. p-
N,N-diethylaminobenzaldehyde-N,
N-diphenylhydrazone) or oxadiazole compounds (e.g. 2,5-bis-(p-diethylaminophenyl)-1,3,4-oxadiazole), pyrazoline compounds (e.g. 1-p-diethylaminophenyl- A photoreceptor with extremely excellent performance can also be obtained by mixing it with a compound such as 3,5-diphenylpyrazoline. Various methods are known for using these hydrazone compounds as electrophotographic photoreceptors.
For example, a photosensitive material prepared by dissolving or dispersing the present hydrazone compound and a sensitizing dye in a binder, with the addition of a chemical sensitizer or an electron-withdrawing compound if necessary, on a conductive support. or on a carrier generating layer provided mainly with a sensitizing dye or pigment on a conductive support in the form of a layered structure consisting of a carrier generating layer with extremely high charge carrier generating efficiency and a carrier transport layer,
There are photoreceptors that have the present hydrazone compound dissolved or dispersed in a binder with the addition of a chemical sensitizer or an electron-withdrawing compound if necessary, as a carrier transport layer. It can also be applied to In preparing photoreceptors using the compounds of the present invention, the compounds of the present invention may be applied onto a support such as a metal plate, conductively treated paper, or conductively treated plastic film with the aid of a polymerizable film-forming binder. Borrow it and make it into a film. In this case, in order to further increase the sensitivity, it is desirable to add a sensitizer as described below or a substance that imparts plasticity to the polymerizable film-forming binder to form a uniform photosensitive layer film. Various polymeric film-forming binders can be used depending on the field of use. In other words, in the field of photoreceptors for copying, polystyrene resins, styrene-butadiene copolymer resins, polyvinyl acetal resins, diallyl phthalate resins, silicone resins, polysulfone resins, polycarbonate resins, acrylic resins, methacrylic resins,
Preferred are vinyl acetate resin, vinyl chloride-crotonic acid copolymer resin, polyphenylene oxide resin, polyester resin, alkyd resin, and the like. These can be used alone or in combination as a copolymer. Among them, resins such as polystyrene, polyphenylene oxide, and polycarbonate have a volume resistivity, and binders with a resistivity of 10 ¹² Ωcm or more have excellent film properties, potential properties, etc.
The amount of these binders added to the organic photoconductor is 0.2 to 20 times the weight ratio, preferably 0.5
-5 times, if it is less than 0.5 times, there will be a disadvantage that the organic photoconductor will precipitate from the surface of the photosensitive layer, and if it is more than 5 times, it will cause a decrease in sensitivity. For use in lithography, particularly alkaline binders are required. An alkaline binder is an acidic group that is soluble in an aqueous or alcoholic alkaline solvent (including mixed systems), such as an acid anhydride group, a carboxyl group, a phenolic hydroxyl group, a sulfonic acid group, a sulfonamide group, or a sulfone group. It is a polymer substance with imide groups. The binder preferably has a high acid value, usually 100 or more. A binder resin with a high acid value easily dissolves or swells in an alkaline solvent. Examples of these binder resins include:
Styrene: maleic anhydride copolymer, vinyl acetate: maleic anhydride, vinyl acetate: crotonic acid, (meth)acrylic acid: (meth)acrylic acid ester, phenolic resin, (meth)acrylic acid: styrene: (meth)acrylic It is a copolymer of acid ester, etc. Further, the proportion of these resins added to the photoconductor may be approximately the same as in the case of a photoconductor for copying. Next, depending on the polymer film-forming binder used, the photosensitive layer may be rigid and weak in mechanical properties such as tension, bending, and compression, and a substance that imparts plasticity may be added to improve these properties. It is also necessary in some cases. These substances include phthalate esters (e.g. DOP, DBP, DIDP, etc.), phosphate esters (e.g. TCP, TOP, etc.), sebacate esters,
Examples include adipic acid ester, epoxidized soybean oil, nitrile rubber, and chlorinated hydrocarbons. In addition, the proportion of these plasticity-providing substances added to the polymerizable film-forming binder is determined by weight.
It is preferably between 0.1% and 20%; less than 0.1% is insufficient for improvement, and more than 20% deteriorates the potential characteristics. Next, the sensitizing dyes added to the photosensitive layer include triphenylmethane dyes such as methyl violet, crystal violet, ethyl violet, night blue, and Victoria blue, erythrosine, rhodamine B, and rhodamine.
3B, Acridine Red B, etc., acridine dyes such as Acridine Orange 2G, Acridine Orange R, Flaveosin, etc.; thiazine dyes such as methylene blue, methylene green, methyl violet, etc.; Examples include oxazine dyes such as Meldora Blue, other cyanine dyes, styryl dyes, pyrylium salts, and thiapyrylium salts. Photoconductive pigments that generate charge carriers with extremely high efficiency through light absorption in the photosensitive layer include phthalocyanine pigments such as metal phthalocyanine and metal-free phthalocyanine, perylene pigments such as perylene imide and perylene acid anhydride, and others. These include quinacridone pigments, azo pigments, and anthraquinone pigments. Further, the dye added to the photosensitive layer described above may be used as a charge carrier generating substance. Although these dyes may be used alone, they often generate charge carriers with even higher efficiency when used together with pigments. Furthermore, inorganic photoconductive materials include selenium, selenium-tellurium alloys, cadmium sulfide, zinc sulfide, and the like. In addition to the sensitizers listed above (spectral sensitizers), sensitizers (chemical sensitizers) are used to further increase sensitivity.
It is also possible to add. Examples of chemical sensitizers include p-chlorophenol, m-chlorophenol, p-nitrophenol, 4-chloro-m
-Cresol, p-chlorobenzoylacetanilide, N,N-diethylbarbituric acid, N,
N'-diethylthiobarbituric acid, 3-(β-oxyethyl)-2-phenylimino-thiazolidone, malonic acid dianilide, 3,5,3',5'-tetrachloromalonic acid dianilide, α-naphthol,
p-nitrobenzoic acid, etc. Further, certain electron-withdrawing compounds can be added as sensitizers that combine with the hydrazone compound of the present invention to form a charge transfer complex and further increase the sensitizing effect. Examples of the electron-withdrawing substance include 1-chloroanthraquinone, 1-nitroanthraquinone, 2,3-dichloro-naphthoquinone,
3,3'-Dinitrobenzophenone, 4-nitrobenzalmalononitrile, phthalic anhydride, 3-(α
-cyano-p-nitrobenzal) phthalide, 2,
4,7-trinitrofluorenone, 1-methyl-
4-nitrofluorenone, 2,7-dinitro-
Examples include 3,6-dimethylfluorenone. Other additives in the photoreceptor include antioxidants,
An anti-curl agent, etc. can be added as necessary. The hydrazone compound of the present invention is dissolved or dispersed in an appropriate solvent together with the various additives mentioned above depending on the form of the photoreceptor, the coating solution is applied onto the conductive support mentioned above, and then dried. A photoreceptor is manufactured. Coating solvents include aromatic hydrocarbons such as benzene, toluene, kyzylene, and monochlorobenzene, chlorinated hydrocarbons such as chloroform, dichloroedane, and trichlorethylene, ethers such as dioxane and tetrahydrofuran, and esters such as ethyl acetate and methyl cellosolve acetate. A single solvent or a mixture of two or more solvents such as
Further, if necessary, solvents such as alcohols, acetonitrile, N,N-dimethylformamide, and methyl ethyl ketone may be further added and used. EXAMPLES Next, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to these in any way. Example 1 Polyester film laminated with aluminum (Alpetsu 85 manufactured by Mitsubishi Plastics, film thickness
85μ, Al foil 10μ) as a support, and on top of that, the structural formula 1 bisazo pigment shown in n-butylamine
Apply the dissolved solution to a concentration of % by weight,
It was dried to form a film of charge generating material having a thickness of 0.2 μm. Next, a hydrazone compound shown by Exemplary Compound 1 and a polycarbonate resin (manufactured by Mitsubishi Gas Chemical Co., Ltd., Iupilon N-6) were blended at a weight ratio of 1:1.2,
A 10% by weight solution was prepared using dichloroethane as a solvent, and this solution was applied onto the film of the carrier generating substance using an air knife and dried to form a film with a thickness of 12 μm.
A carrier moving layer was formed. The laminated electrophotographic photoreceptor produced in this way was tested using an electrostatic recording paper tester (SP manufactured by Kawaguchi Electric Co., Ltd.).
-428) was used to evaluate the electrophotographic characteristics. Applied voltage -6KV, static -3 (turntable rotation speed mode; in this case 10m/min) As a result, the light half-reduction exposure sensitivity to white light during charging was 2.5 lux sec, which is a very high sensitivity value. Ta.
Furthermore, when we conducted a repeated characteristic evaluation using the same device, we found that even after repeating it more than ¹⁰ times,
No tendency to decrease in various electrophotographic properties including light half-life exposure sensitivity was observed. Examples 2 to 10 The hydrazone compounds shown in Table 1 were prepared in Example 1.
A laminated photoreceptor was prepared in the same manner as in Example 1, except that the hydrazone compound was used in place of the hydrazone compound used in Example 1, and the half-light exposure and initial potential (volts) were measured under the same measurement conditions as in Example 1. are shown in Table 1.
Table 1 shows the initial potential (volt) and half-light exposure sensitivity after performing the same operation for 1000 cycles, with 1 cycle of static electricity application and static neutralization (static neutralization light: white light irradiated at 400 lux for 1 second). Indicated. It can be seen from Table 1 that the photoreceptor using the hydrazone compound of the present invention has excellent sensitivity and repeatability.

[Table] Example 11 A laminated photoreceptor was prepared in the same manner as in Example 1 except that a trisazo pigment having the following structural formula was used instead of the bisazo pigment used in Example 1. (however

[Formula]) The 633nm (He−
The energy required to halve the given potential when measuring the spectral sensitivity at 680 nm (Ne laser) and 680 nm (light emitting diode) using a monochrome meter is 3.5 erg/cm ²
(633nm) and 3.2erg/cm ² (680nm), making it an extremely sensitive photoreceptor. Examples 12 to 20 0.2 g of the trisazo pigment used in Example 11 was added to 30 ml of a dichloromethane solution in which 0.1 g of polyarylate resin (V-100 manufactured by Unitika) was dissolved, and the mixture was mixed in a paint conditioner (manufactured by Red Rebel Co., Ltd.). Dispersion was carried out for about 20 minutes, and a charge generation layer was formed on Arpet 85 by the doctor blade method so that the film thickness after drying was 0.4 μm. A charge transfer layer containing the hydrazone compound of Examples 2 to 10 was laminated on the charge generation layer to prepare a photoreceptor. The spectral sensitivities of these photoreceptors at 633 nm and 680 nm were measured in the same manner as in Example 11, and the energy required to reduce the potential by half is listed in Table 2.

[Table] It can be seen that the spectral sensitivities of all photoreceptors at both 630 nm and 680 nm are less than 5.0 erg/cm ² , which is an excellent performance. Also, the energy that makes the residual potential at 630nm and 680nm 0 is different for any photoreceptor.
None exceeded 20erg/ ^cm2 . Example 21 0.3 g of the trisazo pigment used in Example 11 and 0.05 g of the polymethine dye shown in the structure below were dispersed in dichloroethane (the polymethine dye was completely dissolved), and then a 10% polyarylate resin solution was added to this dispersion. was added to the solution to give a total solids concentration of 3%, and further dispersed again in a paint conditioner for about 1 hour. The film thickness after drying the liquid prepared in this way is
It was applied onto Arpet 85 to a thickness of 0.3μ. Next, the hydrazone compound solution used in Example 11 was applied in a layered manner onto the carrier generation layer using a doctor blade method to form a carrier transfer layer with a thickness of about 13μ. The electrophotographic photoreceptor produced in this way
When the spectral sensitivities at 780nm, 800nm, and 830nm were measured in the same manner as in Example 11, they were 3.7erg/cm ² , 3.4erg/cm ² ,
It was found that the photoreceptor has a high sensitivity of 3.2erg/cm ² even in near-infrared light. Example 22 Styrene:maleic anhydride copolymer (styrene content 50 mol%) and Exemplary Compound 12 were blended at a weight ratio of 1.5:1 on an Al plate with a grained surface oxidation.
5×
10 ^-3 and dioxane as a solvent.
% by weight solution, apply this solution with an S-doctor (wire bar) and dry it to a film thickness of about 5 μm.
A single-layer photoreceptor was created. The electrophotographic characteristics of the thus prepared photoreceptor were evaluated using the electrostatic recording paper tester described above. Evaluation conditions: applied voltage -6KV, static -3
The initial potential was -480V, and the light half-light exposure was 5.3lux·sec. In addition, this photoreceptor is visualized with a developer (toner), and then an alkaline processing solution (for example, 3% triethanolamine, 10% ammonium carbonate, and 20% polyethylene glycol with an average molecular weight of 190 to 210) is applied.
When treated with water, the toner-free areas were easily eluted, and by washing with water containing sodium silicate, a printing original plate could be easily prepared.
When offset printing is performed using this original plate, approximately 10
It was found that it can withstand printing of 10,000 copies. The optimum exposure amount (light source: halogen lamp) for obtaining a visible toner image was 50 lux and 0.3 seconds.
In addition, when creating the original printing plate, it was done by direct plate making without using any printing material. Example 23 Instead of the thiapyrilliium salt dye used in Example 22, ε-type copper phthalocyanine was added at a ratio of 10 ^-1 of the hydrazone compound of the exemplary compound, the phthalocyanine was sufficiently dispersed in a ball mill, and the film thickness was adjusted in the same manner as in Example 22. A single-layer photoreceptor with a thickness of about 4μ was created. When looking at the electrophotographic characteristics of this photoreceptor, it was found that the initial potential was +380V and the light exposure was 6.2lux·sec. The photoreceptor thus obtained was exposed in the same manner.
It was found that the printing original plate obtained by development, alkaline treatment, and water washing was able to withstand printing of about 100,000 sheets as in Example 22. For exposure, monochromatic light of 633 nm was used, and the optimum irradiation energy was about 80 erg/cm ² .

Claims (1)

[Scope of Claims] 1. A photoreceptor for electrophotography, characterized in that a hydrazone compound represented by the following general formula () or () is contained in a photosensitive layer formed on a conductive support. (In the formula, R ₁ is an alkyl group, allyl group, propenyl group, phenyl group, benzyl group, R ₂ is hydrogen, alkyl group, halogen, alkoxy group, R ₃ is hydrogen,
Alkyl group, R ₄ is hydrogen, halogen, alkyl group,
Represents an alkoxy group. ) 2. The electrophotographic photosensitive layer 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 () or (). body. 3. The electrophotographic photoreceptor according to claim 1, wherein the hydrazone compound represented by the general formula () is a compound represented by the following structural formula. (In the formula, n is 1 to 4, and R ₂ , R ₃ , and R ₄ have the same meanings as in Item 1.) 4. The hydrazone compound represented by the general formula () is a compound represented by the following structural formula. The electrophotographic photoreceptor according to item 1. (In the formula, n, R ₂ , R ₃ , and R ₄ have the same meanings as in Item 3.) 5. Claim 1, wherein the hydrazone compound represented by the general formula () is a compound represented by the following structural formula. Photoreceptor for electrophotography. (In the formula, R ₂ , R ₃ , and R ₄ have the same meanings as in paragraph 1.) 6. An electrophotographic photograph according to claim 1, wherein the hydrazone compound represented by the general formula () is a compound represented by the following structural formula. Photoreceptor for use. (In the formula, R ₂ , R ₃ , and R ₄ have the same meanings as in item 1.) 7. An electrophotographic photograph according to claim 1, wherein the hydrazone compound represented by the general formula () is a compound represented by the following structural formula. Photoreceptor for use. (In the formula, R ₂ , R ₃ , and R ₄ have the same meanings as in Item 1.) 8. An electrophotographic photograph according to Claim 1, wherein the hydrazone compound represented by the general formula () is a compound represented by the following structural formula. Photoreceptor for use. (In the formula, R ₂ , R ₃ , and R ₄ have the same meanings as in Item 1.) 9. An electrophotographic photograph according to Claim 1, wherein the hydrazone compound represented by the general formula () is a compound represented by the following structural formula. Photoreceptor for use. _10. The electrophotographic photoreceptor according to claim 1, wherein the hydrazone compound represented by the general formula () is a compound represented by the following structural formula. _11. The electrophotographic photoreceptor according to claim 1, wherein the hydrazone compound represented by the general formula () is a compound represented by the following structural formula. (In the formula, R ₂ , R ₃ , and R ₄ have the same meanings as in item 1.) 12. The electrophotography according to claim 1, wherein the hydrazone compound represented by the general formula () is a compound represented by the following structural formula. Photoreceptor for use. (In the formula, R ₂ , R ₃ , and R ₄ have the same meanings as in claim 1.) 13. The electrophotographic photoreceptor according to claim 2, wherein the carrier generating substance is a trisazo pigment. 14. The electrophotographic photoreceptor according to claim 2, wherein the carrier generating substance is a bisazo pigment. 15. The electrophotographic photoreceptor according to claim 2, wherein the carrier generating substance is a phthalocyanine pigment.