JPH0469945B2 - - Google Patents

Description

[Detailed description of the invention]

(A) Industrial Application Field The present invention relates to an electrophotographic photoreceptor, and more specifically, a photosensitive layer formed on a conductive support contains a bisstilbene compound represented by the following general formula (). This invention relates to an electrophotographic photoreceptor. (In the formula, R ₁ and R ₂ are hydrogen, a substituted or unsubstituted lower alkyl group, a lower alkoxy group, or a halogen,
A represents an alkyl group, a substituted or unsubstituted aralkyl group, an aryl group, or an allyl group, and n represents an integer from 1 to 8. ) (B) Prior art and its problems Conventionally, inorganic materials such as selenium, cadmium sulfide, amorphous silicon, and zinc oxide have been widely used in the photosensitive layer of electrophotographic photoreceptors in electrophotographic technology. In recent years, much research has been conducted on the use of organic photoconductive materials as 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,
Although cadmium sulfide has the necessary basic properties to be used as a photoreceptor, there are manufacturing problems such as high toxicity and difficult film formation.
It has drawbacks such as lack of flexibility and high manufacturing costs, and in the future, it will be more likely to be caused by toxicity than by the use of these inorganic materials, which have limited production due to the depletion of resources. In terms of pollution, it is desired to use photoreceptors made of organic materials rather than inorganic materials. 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 are some things. Looking at the general formula, organic materials have better transparency than inorganic materials, are lighter in weight, are easier to form into films, have both positive and negative chargeability, and are easier to manufacture photoreceptors. It has advantages such as being easy to use. By the way, typical examples of organic electrophotographic photoreceptors that have been proposed so far include polyvinylcarbazole and its derivatives, but these do not necessarily have film properties, flexibility, solubility, adhesive properties, etc. In addition, polyvinylcarbazole was sensitized with pyrylium salt dye (Special Publication 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. (C) Purpose of the Invention As a result of research into photoconductive substances with high sensitivity and high durability, the present inventors found that the bisstilbene compound represented by the above general formula () is effective, and the present invention It came to this. (D) Specific Structure of the Invention The bisstilbene compound of general formula () according to the present invention is usually synthesized by the following synthesis process. (In the above reaction formula, R ₁ , R ₂ , A, and n have the same meanings as in the previous section.) Here, the synthesis process will be specifically described. First, the Ia synthesis process can be easily synthesized by the usual Wilsmeier reaction. In the synthesis process of Ib, a benzyl halide derivative and triethyl phosphite are first heated at 150 to 180°C in an oil bath.
The reaction is allowed to proceed for ~10 hours (benzene, toluene, etc. may be used as a solvent if necessary), and the generated haloethyl is distilled off, followed by distillation under reduced pressure to obtain a diethyl benzylphosphonate compound. The diethyl benzylphosphonate compound thus obtained and the bisaldehyde compound obtained in Ia can be easily reacted at a molar ratio of 2:1 in a solution of sodium dissolved in ethanol at room temperature for 2 to 3 hours. can be obtained. Moreover, caustic soda or caustic potash may be used as a catalyst instead of sodium. In some cases, it may be necessary to raise the reaction temperature to about 100°C. Specific examples of the bisstilbene compound useful in the present invention represented by the general formula () include those having the following structural formula.

【table】

【table】

【table】

[Table] 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, hydrazone compounds (e.g. P-N,N-diethylaminobenzaldehyde-N,N-diphenylhydrazone) or oxadiazole compounds (e.g. 2,5-bis-(p-diethylaminophenyl)-1,3,4- A photoreceptor with extremely excellent performance can also be obtained by mixing a compound such as oxadiazole) pyrazoline compound (for example, 1-p-diethylaminophenyl-3,5-diphenylpyrazoline). Various methods are known for using these bisstilbene compounds as electrophotographic photoreceptors. A conductive support in the form of a photoreceptor formed by dissolving or dispersing it in a binder on a conductive support, or in the form of a laminated structure consisting of a carrier generation layer and a carrier transfer layer with extremely high charge carrier generation efficiency. This hydrazone compound is dissolved or dispersed in a binder with the addition of a chemical sensitizer or an electron-withdrawing compound if necessary, on a carrier-generating layer mainly composed of a sensitizing dye or pigment. There is a photoreceptor in which a carrier transport layer is provided with a carrier transfer layer, but it can be applied to any case. When producing a photoreceptor using the compound of the present invention, a polymer film is formed on a support such as a metal cylinder, a metal plate, a conductive treated paper, or a conductive treated plastic film. Form into a film with the help of a binder. In this case, in order to further increase the sensitivity, it is desirable to add a substance imparting plasticity to the sensitizer or polymerizable film-forming binder as described below to form a uniform photosensitive layer film. Various types of polymer film-forming binders can be used depending on the field of use. In other words, in the field of photoreceptors for copying, polystyrene resins, polyvinyl acetal resins, polysulfone resins, polycarbonate resins, vinyl acetate:crotonic acid copolymer resins, polyphenylene oxide resins, polyester resins, alkyd resins, polyarylate resins, etc. preferable. These can be used alone or as copolymers.
It can be used as a species or as a mixture of two or more kinds. Among them, polystyrene, polyphenylene oxide,
Resins such as polycarbonate and polyarylate resins have a volume resistivity of 10 ¹³ Ω or more and excellent film characteristics, potential characteristics, and the like. The amount of these binders added to the organic photoguide is 0.2 to 20 times the weight ratio, preferably 0.5 to 20 times.
If it is less than 0.5 within a 5-fold range, there will be a drawback that the organic photoconductor will precipitate from the surface of the photosensitive layer.
Moreover, if it becomes 5 times or more, sensitivity decreases. Especially alkaline binders are required for use in lithography. An alkaline binder refers to an acidic group that is soluble in water or an 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 sulfonimide group. It is a polymer substance with 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. These binder resins include, for example, styrene:
Maleic anhydride copolymer, vinyl acetate: maleic anhydride, vinyl acetate: crotonic acid, (meth)acrylic acid: (meth)acrylic ester, phenolic resin, (meth)acrylic acid: styrene: (meth)acrylic ester It is a copolymer of Further, the proportion of these resins added to the photoconductor may be approximately the same as in the case of a photoconductor for copying. In the polymer film-forming binder used next, the photosensitive layer is hard and weak in mechanical properties such as tension, bending, and compression, so it is necessary to add a substance that imparts plasticity to improve these properties. becomes. These substances include phthalates (e.g. DOP, DBP, DIDP, etc.), phosphates (e.g. TCP, TOP, etc.), sebacates,
Examples include adipic acid ester, epoxidized soybean oil, nitrile rubber, and chlorinated hydrocarbons. or,
The weight ratio of these substances imparting plasticity to the polymerizable film-forming binder is 0.1.
It is preferably between % and 20%, and below 0.1%,
This is insufficient for improvement, and if it exceeds 20%, the potential characteristics will deteriorate. 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, and Flaveosin; thiazine dyes such as Methylene Blue, Methylene Green, and Methyl Violet; Capri Blue; Examples include oxazine dyes such as Meldora Blue, other cyanine dyes, styryl dyes, pyrylium salts, and thiapyrylium salts. In the photosensitive layer, photoconductive pigments that generate electrolytic carriers with extremely high efficiency through light absorption include phthalocyanine pigments such as metal phthalocyanine and metal-free phthalocyanine, and perylene pigments such as perylene imide and perylene acid anhydride. pigment,
Other examples include quinacridone pigments, azo pigments, and anthquinone pigments. In particular, those using trisazo pigments, bisazo pigments, and phthalocyanine pigments as charge carrier generating pigments provide high altitude and provide excellent electrophotographic photoreceptors. 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 higher efficiency when used together with pigments. Furthermore, as inorganic photoconductive substances, selenium,
Examples include selenium tellurium alloy, cadmium sulfide, and zinc sulfide. 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,
Examples include 3,5,3',5'-tetrachloromalonic acid dianilide, α-naphthol, and p-nitrobenzoic acid. Further, certain electron-withdrawing compounds can be added as sensitizers that combine with the bisstilbene compound of the present invention to form a charge transfer complex and further increase the sensitizing effect. Examples of this electron-withdrawing substance include 1-chloroanthraquinone, 1-nitroanthraquinone,
2,3-dichloro-naphthoquinone, 3,3-dinitrobenzophenone, 4-nitrobenzalmalonenitrile, phthalic anhydride, 3-(α-cyano-p-
Examples include nitrobenzal) phthalide, 2,4,7-trinitrofluorenone, 1-methyl-4-nitrofluorenone, and 2,7-dinitro-3,6-dimethylfluorenone. Other additives in photoreceptors for antioxidant purposes,
An anti-curl agent or the like can be added as necessary. The bisstilbene 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, and the coating solution is applied onto the conductive support described above and dried. A photoreceptor is manufactured. Coating solvents include benzene, toluene, xylene, monochlorobenzene, etc., aromatic hydrocarbons, dioxane, methyl cellosolve acetate, etc. alone or in combination of two or more, and if necessary, alcohols, acetonitrile, N,
A solvent such as N-dimethylformamide or methyl ethyl ketone may be further added. EXAMPLES Next, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited by these in any way. Example 1 Polyester film laminated with aluminum (Alpetsu 85 manufactured by Mitsubishi Plastics, film thickness
85μ, aluminum film thickness 10μ) as a support and the following structural formula is placed on it. 1 bisazo pigment shown in n-butylamine
A solution dissolved at a concentration of % by weight was applied and dried to form a film of the charge generating substance with a thickness of 0.2 μm. Next, the bisstilbene compound shown in Exemplary Compound No. 5 and polyarylate resin (Unitika U-Polymer) were blended at a weight ratio of 1:1.2, and a 10% solution was prepared using dichloroethane as a solvent. This solution was applied onto the film using an applicator to form a carrier transfer layer with a dry film thickness of 19 μm. The electrophotographic properties of the thus produced laminated electrophotographic material were evaluated using an electrostatic recording paper tester (SP-428 manufactured by Kawaguchi Electric Co., Ltd.). Measurement conditions: Applied voltage -6 KV, Statute No. 3 As a result, the light half-reduction exposure sensitivity to white light during charging was 2.0 lux·sec, a very high sensitivity value. Furthermore, when repeated characteristic evaluations were conducted using the same apparatus, no tendency for electrophotographic characteristics to deteriorate, including light half-reduction exposure sensitivity, was observed even after repeating the evaluation ¹⁰³ times or more. Examples 2 to 6 Laminated photoreceptors were prepared in the same manner as in Example 1, except that the bisstilbene compounds shown in Table 1 were used in place of the bisstilbene compounds used in Example 1, and Under similar measurement conditions, the optical half-reduction exposure E1/2 (lux seconds) and the initial potential Vo (volts) were measured, and the values are shown in Table 1. Furthermore, the initial potential Vo (volts) 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)
Table 1 shows the light half-decrease exposure sensitivity E1/2 (lux seconds). It can be seen from Table 1 that the photoreceptor using the bisstilbene compound of the present invention has excellent sensitivity and repeatability.

[Table] Example 7 A laminated photoreceptor was prepared in the same manner as in Example 1 except that a triazo pigment having the following structural formula was used in place of the bisazo pigment used in Example 1. however The 633nm (He
-Ne laser) and 670nm (light emitting diode)
When the spectral sensitivity was measured using a monochromator, the energy required to reduce the potential by half was
It was a photoreceptor with extremely high sensitivity of 5.4erg/cm ² (633nm) and 4.7erg/cm ² (670nm). Furthermore, the initial potential is
It was 830 (volts). Examples 8 to 12 0.2 g of the trisazo pigment used in Example 7 was added to 30 ml of a dichloromethane solution in which 0.1 g of polyarylate resin (U-100 manufactured by Unitika) was dissolved, and the mixture was mixed in a paint conditioner (manufactured by Red Level Co., Ltd.) for about 20 g. Dispersion was carried out for several 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 bisstilbene compounds of Examples 2 to 6 was laminated on this charge generation layer to prepare a photoreceptor. The spectral sensitivities of these photoreceptors at 633 nm and 670 nm were measured in the same manner as in Example 9, and the energy required to reduce the potential by half is listed in Table 2.

[Table] Example 13 Copolymer nylon (Toyo Rayon CM-
8000) Add to 30ml of 5% by weight solution to make a homogeneous solution. The film thickness after drying the solution prepared in this way is
It was coated onto an aluminum vapor-deposited film to a thickness of 0.2μ. Next, Exemplified Compound No. 32, Bisstilbene Compound 2
Dissolve 1.5 g of styrene resin (Mitsubishi Monsanto Styron-85) and 0.8 g of poly n-butyl acrylate resin (manufactured in-house) in 20 ml of toluene, and apply this solution in a layered manner on the carrier generation layer using the doctor blade method. A carrier transport layer of about 10 μm was formed. 780n of electrophotographic photoreceptor made in this way
When the spectral sensitivities at m, 820nm, and 840nm were measured in the same manner as in the example, they were 12erg/cm ² (780nm) and 10erg/cm 2 (780nm).
cm ² (820 nm) and 8 erg/cm ² (840 nm), indicating that it is a highly sensitive photoreceptor even in near-infrared light. Example 14 Styrene on Al plate with grained surface oxidation:
Ethyl methacrylate: methacrylic acid (styrene: ethyl methacrylate = 3:1 weight ratio, acid value
185) and Exemplified Compound No. 19 at a weight ratio of 1.5:1, 4-(p-diethylaminophenyl)-2,6
-di-p-tolylthiapyrylium perchlorate (thiapyrylium salt dye) in 5×
10 ^-3 and dioxane as a solvent to make a 10% solution by weight, apply this solution with a squeegee doctor and dry it to a film thickness of approx.
A 5μ 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 410 (volts) and the half-light exposure was 7.5 (lux seconds). In addition, when this photoreceptor is visualized with a developer (toner) and then treated with an alkaline processing solution (for example, 3% triethanolamine, 10% ammonium carbonate, and 20% polyethylene glycol with an average molecular weight of 190 to 210), the toner The non-adherent 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
It was found that it could withstand printing of 100,000 sheets. The optimum exposure amount (light source: halogen lamp) for obtaining a visible toner image was 50 lux and 1 second. In addition, when creating a printing original plate, it was performed by direct plate making without using a base material. Example 15 Instead of the thiapyrylium salt dye used in Example 14, ε-type copper phthalocyanine was added at a weight ratio of 10% of the hydrazone compound of the exemplary compound, the phthalocyanine was sufficiently dispersed in a ball mill, and the film thickness was determined in the same manner as in Example 18. A single-layer photoreceptor with a thickness of about 4μ was created. Looking at the electrophotographic characteristics of this photoreceptor, the initial potential is
380 (volts), half-light exposure 8.2 (lux seconds)
It was hot. The photoreceptor thus obtained was exposed, developed, alkaline treated and washed with water in the same manner, and the printing original plate obtained was found to be able to withstand printing of about 100,000 sheets as in the example. For exposure, monochromatic light of 633 nm was used, and the optimum irradiation energy was about 120 erg.

Claims (1)

[Scope of Claims] 1. An electrophotographic photoreceptor characterized by containing a bisstilbene compound represented by the following general formula () in a photosensitive layer formed on a conductive support. (In the formula, R ₁ and R ₂ are hydrogen, a substituted or unsubstituted lower alkyl group, a lower alkoxy group, or a halogen,
A is an alkyl group, a substituted or unsubstituted aralkyl group,
represents an aryl group or an allyl group, n is 1 to 8
Represents an integer up to. ) 2 The electrophotographic photoreceptor according to claim 1, wherein the bisstilbene compound represented by the general formula () is a compound represented by the following structural formula. (In the formula, R ₂ has the same meaning as in paragraph 1.) 3. The electrophotographic photoreceptor according to claim 1, wherein the bisstilbene compound represented by the general formula () is a compound represented by the following structural formula. . (In the formula, m is an integer from 0 to 3, and R ₂ has the same meaning as in the first term.) 4. The bisstilbene compound represented by the general formula () is a compound represented by the following structural formula. The electrophotographic photoreceptor according to scope 1. (In the formula, R ₂ has the same meaning as in paragraph 1.) 5. A patent in which the photoreceptor contains a carrier transfer substance and a carrier generation substance, and the carrier transfer substance is a bisstilbene compound represented by the general formula (). An electrophotographic photoreceptor according to claim 1. 6. The electrophotographic photoreceptor according to claim 5, wherein the carrier generating substance is a trisazo pigment. 7. The electrophotographic photoreceptor according to claim 5, wherein the carrier generating substance is a bisazo pigment. 8. The electrophotographic photoreceptor according to claim 5, wherein the carrier generating substance is a phthalocyanine pigment.