JPH0229208B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an electrophotographic photoreceptor containing a novel chemically stable oxazole derivative. Conventionally, oxazole derivatives include 2-(4
-dipropylaminophenyl)-4-(4-dimethylaminophenyl)-5-(2-chlorophenyl)
-1,3-oxazole [compound ()], 2-
(4-diethylaminophenyl)-4-(4-dimethylaminophenyl)-5-(2-chlorophenyl)-1,3-oxazole [compound ()], 2
-(4-dimethylaminophenyl)-4-(4-dimethylaminophenyl)-5-(2-chlorophenyl)-1,3-oxazole [compound ()], etc. are known, and are used for copying machines and It is used as an electrophotographic material for laser beam printers (Japanese Patent Application Laid-open No. 123544/1983). However, this oxazole derivative is particularly easily decomposed by ultraviolet irradiation in a solution state, and the decomposition products are mainly 2-(4-dipropylaminophenyl)-6-dimethylaminophenanthro[9 ，
10-d] Since oxazole is generated and its properties are destroyed, care must be taken when handling it, and in particular, it has the disadvantage that its properties are easily destroyed during the production of electrophotographic photoreceptors. The present invention aims to solve these problems, and provides an electrophotographic photoreceptor containing an oxazole derivative, which is a novel compound and has properties that are stable against ultraviolet irradiation, and has excellent electrophotographic properties. In particular, it is an object of the present invention to provide an electrophotographic photoreceptor whose characteristics are not destroyed even during its manufacture. That is, the present invention provides the general formula () The present invention relates to an electrophotographic photoreceptor containing an oxazole derivative represented by the formula (wherein R ₁ , R ₂ , R ₃ and R ₄ represent an alkyl group, and may be the same or different). The compound represented by the above general formula () has an F atom instead of the Cl atom in the above compounds (), (), and (), and because of this, it has very high stability against ultraviolet rays. It does not decompose even when exposed to ultraviolet rays, and provides stable and excellent properties to electrophotographic photoreceptors. The oxazole derivative represented by the general formula () mainly functions as a charge transport substance. This compound can be used with other charge transporting substances, such as polymeric compounds such as poly-N-vinylcarbazole, halogenated poly-N-vinylcarbazole, polyvinylpyrene, polyvinylindoquinone xaline, polyvinylbenzothiophene, polyvinylanthracene, polyvinylacridine. , polyvinylpyrazoline, etc., and low molecular weight compounds such as fluorene, fluorenone, 2,7-dinitro-9-fluorenone, 2,4,7-trinitro-9-fluorenone, and 4H-indeno(1,2,6)thiophene. −
4-one, 3,7-dinitro-dibenzothiophene-5-oxide, 1-brompine, 2-phenylpyrene, carbazole, 3-phenylcarbazole, 2-phenylindole, 2-phenylnaphthalene, oxadiazole, triazole,
1-phenyl-3-(4-diethylaminostyryl)-5-(4-diethylaminophenyl)pyrazoline, 2-phenyl-4-(4-diethylaminophenyl)-5-phenyloxazole, triphenylamine, imidazole, It can be used in combination with chrysene, tetraphene, acridene, derivatives thereof, etc. The blending ratio of other charge transporting substances is preferably 1 part by weight or less per 1 part by weight of the oxazole derivative represented by the general formula () so as not to impair the improvement in electrophotographic properties. Particularly preferred is 0.25 part by weight or less. The electrophotographic photoreceptor according to the present invention can be constructed by forming a single layer containing a mixture of a charge transport material and a charge generation material as a photoconductor layer on a conductive support. It is also possible to form the charge-generating material and the charge-transporting material as separate layers, so that a so-called two-layer structure is constructed as a photoconductor layer on a conductive support. The above charge generating substances include Si, Se, AS ₂ S ₃ ,
Sb ₂ S ₃ , Sb ₂ Se ₃ , CdS, CdSe, CdTe, ZnO, α
metal-free phthalocyanine pigments of various crystal types such as type and β type, metal phthalocyanine pigments such as copper phthalocyanine, aluminum phthalocyanine, zinc phthalocyanine, and cobalt phthalocyanine, azo pigments,
Examples include anthraquinone pigments, indigoid pigments, quinacridone pigments, berylene pigments, polycyclic quinone pigments, and methine squaritate pigments. As the pigment, for example, JP-A-47-37453, JP-A-47-37544, JP-A-47-18543,
JP-A-47-18544, JP-A-48-43942, JP-A-48-70538, JP-A-49-1231, JP-A-49-105536, JP-A-50-
Some of these are disclosed in JP-A No. 75214, JP-A-50-92738, and the like. Known additives such as binders, plasticizers, flow agents, pinhole inhibitors, etc. can be used in the photoconductor layer. As the binder, linear saturated polyester resin, polycarbonate resin, acrylic resin, butyral resin, polyketone resin, polyurethane resin, resin-N-vinylcarbazole,
Poly-(p-vinylphenyl)anthracene, silicone resin, polyamide resin, epoxy resin,
Selected from polystyrene resin, etc. Furthermore, thermosetting and photocuring resins that are crosslinked by heat and/or light can also be used. In any case, there is no particular limitation as long as the resin is insulating and has film-forming ability in a normal state, and/or resin that can be cured by light to form a film. Examples of the plasticizer include halogenated paraffin, dimethylnaphthalene, and dibutyl phthalate. Examples of fluidity imparting agents include Modaflow (manufactured by Monsanto Chemical Company) and Acronal 4F (manufactured by Basf Corporation), and examples of pinhole inhibitors include benzoin and dimethyl terephthalate. These may be selected and used as appropriate, and the amount thereof may be determined as appropriate. When adopting a single layer structure, the amount of the charge transport material to be mixed with the charge generation material is 1 part by weight of the former,
The latter is generally used in an amount of 1 to 10 parts by weight. Preferably, the amount of the latter is 1 to 5 parts by weight per 1 part by weight of the former. The amount of binder used is 1 to 3 parts by weight per 1 part by weight of the charge generating material, and if it exceeds 3 parts by weight, the electrophotographic properties will deteriorate. In addition, the above-mentioned plasticizers and additives are appropriately used in an amount of several percent by weight or less based on the charge generating substance. In addition, the thickness of the entire photoconductor layer is 5~
Generally, the thickness is 100 μm. However, in the end, it is desirable to make a decision so that the photosensitivity, that is, the charging characteristics are not impaired. On the other hand, when a two-layer structure is adopted, the charge generation layer is formed to a thickness of 1 to 20 μm on the conductive support by vacuum evaporation or the like in the case of the above-mentioned Si or Se. Also, Si,
When using an inorganic substance other than Se, an organometallic pigment, or an organic pigment as a charge generating substance, it is necessary to use the above-mentioned binder to form a film, and the amount used is 1 part by weight of the charge generating substance. The amount is 3 parts by weight, and if it exceeds 3 parts by weight, the electrophotographic properties deteriorate. In addition, the above-mentioned plasticizers and additives are appropriately used in an amount of several percent by weight or less based on the charge generating substance. Further, when the charge transporting layer uses an oxazole derivative represented by the general formula () alone as a charge transporting substance, it is common to use 1 to 3 parts by weight of the above-mentioned binder per 1 part by weight of the charge transporting substance. It is.
In addition, when using other charge transporting substances in combination, if the charge transporting substance is a polymer compound, it is not necessary to use a binder, but the amount of binder is not more than 3 parts by weight per 1 part by weight of the polymer compound. May be used in 3
If the amount exceeds parts by weight, the electrophotographic properties will deteriorate. Further, when a low molecular weight compound is used together as the charge transporting substance, the binder is used in an amount of 0.3 to 3 parts by weight per 1 part by weight of the oxazole derivative of the general formula () and the low molecular weight compound. If it is less than 0.3 parts by weight, it will be difficult to form a charge transport layer, and if it exceeds 3 parts by weight, electrophotographic properties will deteriorate. The other plasticizers and additives mentioned above are appropriately used in an amount of 0.05 part by weight or less per 1 part by weight of the charge transporting substance. The thickness of the charge generation layer is preferably 0.01 to 10 μm, preferably 0.2 to 5 μm. If it is less than 0.01 μm, it will be difficult to uniformly form a charge generation layer, and if it exceeds 10 μm, the electrophotographic properties will deteriorate. Further, the thickness of the charge transport layer is 5 to 50 μm, preferably 8 to 25 μm. 5μm
If it is less than 50 μm, the initial potential will decrease, and if it exceeds 50 μm, the sensitivity will decrease. However, in any case, it is desirable that the final determination be made with consideration given to not impairing the photosensitivity, that is, the charging characteristics. Care must be taken because if the thickness of the photoconductive layer becomes too thick, the flexibility of the layer itself may decrease. When the electrophotographic photoreceptor of the present invention has a two-layer structure having a charge-generating substance and a charge-transporting layer, a charge-generating layer is formed on a conductive support, and a charge-transporting layer is formed thereon. Although preferred from the viewpoint of electrophotographic properties, the charge generation layer and the charge transport layer may be reversed. Aluminum, brass, copper, gold, etc. are used for the conductive support. To form a single layer containing a charge-generating substance and a charge-transporting substance on a conductive support, and a double layer consisting of a charge-generating layer and a charge-transporting layer, the components of each layer may be mixed with acetone, a ketone solvent such as methyl ethyl ketone, or tetrahydrofuran. After being uniformly dissolved or dispersed in a solvent such as ether solvents such as ethereal solvents, aromatic solvents such as toluene, xylene, etc., it can be applied and dried on a conductive support. Of these, after the charge generation layer or the charge transport layer is formed, the charge transport layer or the charge generation layer can be similarly applied thereon and dried to form a two-layer structure. For coating and drying, for example, use a doctor blade to coat the film to a specified thickness, let it air dry for 15 minutes, and then
This can be done by drying at 80-110°C for 40 minutes. The electrophotographic photoreceptor according to the present invention may further have a thin adhesive layer or barrier layer immediately above the conductive support. Further, a protective layer such as silicon can be provided on the surface. In the copying method using the electrophotographic photoreceptor of the present invention, as in the conventional method, the surface is charged and exposed, then developed, and the image is transferred and fixed onto plain paper. The electrophotographic photoreceptor of the present invention has excellent advantages such as high sensitivity, low dark decay, and little optical fatigue. As the oxazole derivative represented by the general formula (), 2-(4-dipropylaminophenyl)
-4-(4-dimethylaminophenyl)-5-(2
-fluorophenyl)-1,3-oxazole,
2-(4-diethylaminophenyl)-4-(4-
dimethylaminophenyl)-5-(2-fluorophenyl)-1,3-oxazole, 2-(4-dimethylaminophenyl)-4-(4-dimethylaminophenyl)-5-(2-fluor orphenyls)-1,
3-oxazole, 2-(4-dipropylaminophenyl)-4-(4-diethylaminophenyl)
-5-(2-fluorophenyl)-1,3-oxazole, 2-(4-diethylaminophenyl)-4
-(4-diethylaminophenyl)-5-(2-fluorophenyl)-1,3-oxazole, 2-
(4-dimethylaminophenyl)-4-(4-diethylaminophenyl)-5-(2-fluorophenyl)-1,3-oxazole, 2-(4-dimethylaminophenyl)-4-(4 -dipropylaminophenyl)-5-(2-fluorophenyl)-1,3
-Oxazole, etc. The oxazole derivative represented by the general formula () is (However, in the formula, R ₁ and R ₂ represent an alkyl group such as a methyl group, an ethyl group, or a propyl group, and these may be the same or different.) and a compound represented by the general formula (B) (However, in the formula, R ₃ and R ₄ represent an alkyl group such as a methyl group, an ethyl group, or a propyl group, and these may be the same or different.) Obtainable. For example, the compound represented by formula (A) contains 1 mol each of 4-dimethylaminobenzaldehyde, 2-fluorobenzaldehyde, and KCN;
It can be produced by adding 1 mol and 0.1 to 1.5 mol to a 50% aqueous ethanol solution and heating under reflux for 1.5 to 4 hours. The compound represented by the general formula (B) can be synthesized, for example, by the reaction route represented by the following formula (X). That is, 1 mole of aniline and the general formula (C) (RO) ₃ PO (C) (wherein R represents an alkyl group such as a methyl group, ethyl group, or propyl group, and the three R's may be the same or different. 0.67 mol of a compound represented by the following formula is heated under reflux for 2 hours to react, and distilled under reduced pressure to obtain dialkylaniline (here, the alkyl group includes methyl, ethyl group, propyl group, etc.; the same applies hereinafter). . Subsequently, 0.3 to 0.4 mole of dialkylaniline is added dropwise to 1 mole of N,N-dimethylformamide at 19 to 22°C, and after completion of the dropwise addition, the mixture is reacted at 90 to 95°C for 2 hours and distilled under reduced pressure to obtain dialkylaminobenzaldehyde. Hydroxyamine hydrochloride 1.0 per mole of dialkylaminobenzaldehyde
~1.3 mol % is reacted at room temperature for 20 minutes, and the reaction solution is left in the refrigerator to precipitate dialkylaminobenzaldehyde oxime. Finally, 2 to 3 moles of acetic anhydride are heated under reflux for 20 minutes per mole of dialkylaminobenzaldehyde oxime to cause a dehydration reaction, thereby producing a compound represented by general formula (B). In the above, production of dialkylaminobenznitrile from dialkylaminobenzaldehyde can also be carried out by the route of the following formula (Y). That is, 1.15 mol of NH ₂ OH・HCl per 1 mol of dialkylaminobenzaldehyde,
Mix a large excess of HCOONa and about 1500 c.c. of formic acid,
The reaction was carried out under reflux for 1 hour, and then the reaction solution was immediately added to water to precipitate dialkylaminobenzonitrile. This precipitate may be recrystallized with water. The compound represented by the general formula () can be obtained by dissolving the compounds represented by the formula (A) and the general formula (B) in concentrated sulfuric acid and reacting in a dark place. The reaction temperature is preferably 20 to 70°C. Reaction temperature 50~70℃
The reaction will complete in 0.5 to 2 hours. Purification of the reactant can be carried out by recrystallization with methanol. The compounds represented by general formula (A) and general formula (B) are preferably mixed in advance before the reaction. If the compound of general formula (A) is added alone to concentrated sulfuric acid, it will undergo a dehydration reaction before reacting with the compound represented by general formula (B) by the concentrated sulfuric acid. Examples of the present invention are shown below. Examples 1 to 3 α-type metal-free phthalocyanine (BASF Corporation, trade name
Heliogen Blue 7560) 1 part by weight and 6.7 parts by weight of silicone resin (Shin-Etsu Chemical Co., Ltd. trade name, KR255) were made into a 5% by weight solution using tetrahydrofuran as a solvent. ) for 5 hours. The obtained pigment dispersion was applied onto an aluminum plate (conductor) using an applicator and dried at 90° C. for 40 minutes to form a charge generation layer with a thickness of 1 μm. Next, oxazole derivative 1 shown in Table 1 below
Weight parts and polyester resin (Toyobo Co., Ltd. product name,
2.4 parts by weight of Vylon 200) and 0.6 parts by weight of styrene resin (manufactured by Etsuo, Picotex 100) were made into a 27% by weight solution using tetrahydrofuran as a solvent,
Coat on the above charge generation layer with an applicator.
The mixture was dried at 90° C. for 40 minutes to form a charge transport layer with a thickness of 30 μm to obtain an electrophotographic photoreceptor. The electrostatic recording paper testing device (Kawaguchi Electric Co., Ltd. product name SP) was used for the electrophotographic photoreceptor produced in this way.
-428) to measure electrophotographic properties. In this case, conduct a negative 5KV corona discharge for 10 seconds to charge it (the surface potential V ₀ () immediately after charging for 10 seconds is the initial potential), and leave it in a dark place for 30 seconds (at this time, the surface potential of the nucleus is Expressed as V ₃₀ (), V ₃₀ /V ₀ ×100
is the dark attenuation (%)), the surface is exposed to 2 lux using a tungsten lamp, the attenuation of the surface potential at this time and the time are recorded, and the time t until V ₃₀ becomes 1/2 is recorded. Sensitivity (half-reduced exposure E ₅₀ , in lux/second units) was expressed as the product of (seconds) and illuminance (lux). These results are shown in Table 1 below. Examples 4 to 6 1 part by weight of β-type copper phthalocyanine (manufactured by Dainippon Ink Co., Ltd., Cyanine Plu-LC) and 6.7 parts by weight of silicone resin (trade name, KR255, manufactured by Shin-Etsu Chemical Co., Ltd.) were mixed with 5% by weight of tetrahydrofuran as a solvent. Make a solution using a ball mill (manufactured by Nihon Kagaku Togyo Co., Ltd.).
3-inch pot mill) for 5 hours, and the resulting dispersion was applied and dried in the same manner as in Examples 1 to 3.
A charge generation layer with a thickness of 1 μm was formed. Next, oxazole derivative 1 shown in Table 2 below
Weight parts and polyester resin (Toyobo Co., Ltd. product name,
2.4 parts by weight of Vylon 200) and 0.6 parts by weight of styrene resin (manufactured by Etsuo, Picotex 100) were made into a 27% by weight solution using tetrahydrofuran as a solvent,
Coat on the above charge generation layer with an applicator.
The mixture was dried at 90° C. for 40 minutes to form a charge transport layer with a thickness of 15 μm, thereby obtaining an electrophotographic photoreceptor. The characteristics of the electrophotographic photoreceptor thus prepared were measured in the same manner as in Examples 1 to 3, and the results are shown in Table 2.

【table】

[Production of 4-dimethylamino-2'-fluorobenzoin]

Dimethylaminobenzaldehyde 14.9g, 2-
12.4 g of fluorobenzaldehyde and 8.0 g of potassium cyanide were dissolved in 150 ml of a 50% ethanol solution and heated under reflux for 2 hours and 30 minutes. After heating to reflux, the mixture was allowed to cool, and the precipitated pale yellow crystals were filtered and dried at 80°C.
Recrystallize the crystals with 500ml of methanol to obtain a melting point of 168~
4-dimethylamino-2'-fluorobenzoin (yield 45%) was obtained at 170°C. Production example 2 [Production of 4-dipropylaminobenzonitrile] 62 g of aniline and 100 g of n-propyl phosphate
After heating under reflux for 2 hours, the solution was cooled until the solution temperature reached 55
When the temperature dropped to ~60°C, an aqueous sodium hydroxide solution (56.3 g/225 ml) was added, and the mixture was heated under reflux for 1 hour.
Immediately after heating and refluxing, the reaction solution was transferred to a 1-beaker and left to stand. The reaction solution was separated into two layers, the upper layer was yellow and the lower layer was a white solid. The white solid was extracted three times with 100 ml of ether, and the upper layer and extract were dried over anhydrous sodium sulfate. After distilling off the ether, the same volume of acetic anhydride was added and left overnight. Add aqueous hydrochloric acid solution (45 ml/67.5 ml) to the reaction solution and leave to cool.
When 25% sodium hydroxide solution was added, the mixture was separated into an oil layer and an aqueous layer. The aqueous layer was extracted three times with 100 ml of ether and dried together with the oil layer over anhydrous sodium sulfate. After distilling off the ether, vacuum distillation (b.p130~
(140°C/18mmHg) to obtain dipropylaniline (yield 69%). Next, add 54 g of N,N-dimethylformamide to 20
While maintaining the temperature below 0.degree. C., 44.5 g of phosphorus oxychloride was added dropwise over 30 minutes. 35 g of dipropylaniline obtained above was added dropwise over 1 hour. After the dropwise addition was completed, the mixture was heated and stirred at 90 to 95°C for 2 hours. After that, the reaction solution was added to ice water and neutralized with saturated sodium acetate solution. 5 with 100ml of ether
The extract was extracted twice and dried over anhydrous sodium sulfate. After distilling off the ether, vacuum distillation (bp155-163℃/3mm
Hg) to obtain dipropylaminobenzaldehyde (yield 46%). 11.6g of this dipropylaminobenzaldehyde
was dissolved in 23 ml of 95% ethanol, an aqueous hydroxyamine hydrochloride solution (4.7 g/5.7 ml) was added thereto, and the mixture was stirred for 20 minutes. An aqueous sodium hydroxide solution (3.4 g/4.5 ml) was added to the reaction solution, and the mixture was left at room temperature for 2 hours and 30 minutes. After adding 29 g of ice and replacing the inside of the reaction system with CO ₂ gas, it was left in a refrigerator overnight. The precipitated white crystals were suction filtered, washed with water, and then dried. 12.4 g of acetic anhydride was added to the obtained compound, and the mixture was heated under reflux for 20 minutes. After this, the reaction solution was added to 35 ml of cold water and neutralized with sodium hydroxide solution. ether 40ml
The extract was extracted three times with water and dried over anhydrous sodium sulfate. Distillation under reduced pressure after ether distillation (b.p180℃/4
mmHg) to obtain 4-dipropylaminobenzonitrile (yield 79%). When this was left to stand, it crystallized into yellow crystals with a melting point of 39-41°C. Production Example 3 [Production of 4-dimethylaminobenzonitrile] 29.8 g of dimethylaminobenzaldehyde synthesized according to the procedure of Production Example 2, 15.9 g of hydroxyamine hydrochloride, 25 g of sodium formate, and 333 ml of formic acid.
The mixture was heated under reflux for 1 hour. When the reaction solution was added dropwise to 800 ml of water with stirring, pale green crystals were precipitated. After filtration, dry and recrystallize with acetone, melting point 67-69℃
of 4-dimethylaminobenzonitrile (yield 50
%) was obtained. Production Example 4 [Production of 4-diethylaminobenzonitrile] 25 g of diethylaminobenzaldehyde synthesized according to the procedure of Production Example 2, hydroxyamine hydrochloride
10.5g, sodium formate 16.5g and formic acid 220ml
The mixture was heated under reflux for 1 hour. When the reaction solution was added to 400 ml of water with stirring, white crystals were precipitated. After filtration, dry and recrystallize from water-acetone, melting point 66-67℃.
of 4-diethylaminobenzonitrile (yield 50
%) was obtained. Production Example 5 [Production of Compound ()] 35 g of concentrated sulfuric acid was kept at 60°C in a dark place, and 2.4 g of 4-dimethylamino-2'-fluorobenzoin obtained in Production Example 1 and 2.4 g of 4-dimethylamino-2'-fluorobenzoin obtained in Production Example 2 were added to it. A mixture of 2.1 g of 4-dipropylaminobenzonitrile was added and stirred for 1 hour. When the reaction solution was added to 900 ml of water, a yellow-green precipitate was deposited. After filtration, the filtrate was made alkaline with 3N sodium hydroxide solution to precipitate pale yellow crystals. This was filtered by absorption and air-dried. Recrystallization from methanol gave 1.73 g (yield 43%) of a pale yellow solid. From the analysis results below, this pale yellow solid is 2-
It was confirmed that it was (4-dipropylaminophenyl)-4-(4-dimethylaminophenyl)-5-(2-fluorophenyl)-1,3-oxazole (compound). (1) Melting point: 134-135℃ (2) Elemental analysis value: C ₂₉ H ₃₂ N ₃ OF C H N Calculated value (%) 76.15 7.00 9.19 Actual value (%) 76.07 7.11 9.15 Production example 6 [Compound () Production] 35 g of concentrated sulfuric acid was kept at 60°C in a dark place, and 2.4 g of 4-dimethylamino-2'-fluorobenzoin obtained in Production Example 1 and 1.5 g of 4-dimethylaminobenzonitrile obtained in Production Example 3 were added to it. g mixture was added and stirred for 30 minutes. When the reaction solution was added to 900 ml of water, a yellow-green precipitate was deposited. When the filtered solution was made alkaline with 3N sodium hydroxide solution, pale yellow crystals were precipitated. This was filtered by absorption and air-dried. Recrystallization from methanol gave pale yellow solid 1.56 (yield 44%).
This pale yellow solid is 2-(4-
dimethylaminophenyl)-4-(4-dimethylaminophenyl)-5-(2-fluorophenyl)-
It was confirmed that it was a 1,3 oxazole (compound). (1) Melting point: 172-173℃ (2) Elemental analysis value: C ₂₅ H ₂₄ N ₃ OF C H N Calculated value (%) 74.79 6.03 10.47 Actual value (%) 74.53 6.04 10.47 Production example 7 [Compound () Production] 32 g of concentrated sulfuric acid was kept at 60°C in a dark place, and 2.2 g of 4-dimethylamino-2'-fluorobenzoin obtained in Production Example 1 and 1.64 g of 4-diethylaminobenzonitrile obtained in Production Example 4 were added to it. The mixture was added and stirred for 1 hour. When the reaction solution was added to 800 ml of water, a yellow-green precipitate was deposited. When the filtered solution was made alkaline with 3N sodium hydroxide solution, pale yellow crystals were precipitated. This was filtered by absorption and air-dried. Recrystallization from methanol gave 1.39 g (yield 40%) of a pale yellow solid. From the analysis results below, this pale yellow solid is 2-
It was confirmed that it was (4-diethylaminophenyl)-4-(4-dimethylaminophenyl)-5-(2-fluorophenyl)-1,3-oxazole (compound). (1) Melting point: 102-105°C (2) Elemental analysis value: C ₂₇ H ₂₃ N ₃ OF CH N Calculated value (%) 75.35 6.51 9.77 Actual value (%) 75.25 6.53 9.72 Used in Examples 1 to 3 Oxazole derivatives [(), () and ()] and 2-
The stability test of (4-diethylaminophenyl)-4-(4-dimethylaminophenyl)-5-(2-chlorophenyl)-1,3-oxazole () against ultraviolet irradiation was conducted as follows. Ta. Compounds (), () and () separately 2x
Nitrogen gas was bubbled through each acetonitrile solution at a concentration of 10 ^-4 mol/l for 1 hour, and then irradiated with a 150W high-pressure mercury lamp while blowing nitrogen gas. Samples are taken at 5 minute intervals after the start of irradiation, diluted at a constant rate with an acetonitrile solution, and then changes in the absorption spectrum are examined using an ultraviolet spectrophotometer. The compound () used for comparison showed an initial absorption spectrum (λmax=
363.0nm ε=4.8×10 ⁴ l/mol・cm, 310nm
Absorption spectrum different from shoulder (λmax=
370.0nm, 258.0nm, 245.0nm).
The absorption spectrum of the latter is 2-(4-diethylaminophenyl)-6 produced by decomposition of compound ().
-dimethylaminophenanthro[9,10-d]oxazole. The decomposition rate of the compound () used for comparison was determined from the concentration of decomposed products produced using the Lambart-Beer method from the measurement of the absorbance at 258.0 nm, which appears due to the decomposition of the absorption spectrum at each time. The charge transport materials (), () and () used in the electrophotographic photoreceptor of the present invention have an initial spectrum (V:λmax=363.0nm ε) even after 60 minutes of irradiation.
=4.9× ¹⁰⁴ l/mol・cm, 310.0nm shoulder:：
λmax=359.0nm ε=4.5×10 ⁴ l/mol・cm,
310.0nm shoulder: :λmax=363.0nm ε=
4.5×10 ⁴ l/mol・cm, 310.0 nm shoulder), and the absorption spectrum pattern remains unchanged. The decomposition rate of these compounds was evaluated from the ratio (A _310.0 /Aλmax) of the absorbance at 310.0 nm of the absorption spectrum (A _310.0 ) and the absorbance at λmax (Aλmax) at each time. FIG. 1 shows the time course of the photodecomposition rate of compounds (), (), (), and () when acetonitrile solutions were irradiated with a high-pressure mercury lamp. Curve 1 in Figure 1 is
Curve 2 shows the decomposition rate of compound (), Curve 3 shows the decomposition rate of compound ()
and curve 4 shows the decomposition rate of compound (). As is clear from the above, the electrophotographic photoreceptor according to the present invention is stable against ultraviolet irradiation and has good electrophotographic properties.

[Brief explanation of drawings]

FIG. 1 shows the change over time in the decomposition rate of an acetonitrile solution of compounds (), (), (), and () by irradiation with a high-pressure mercury lamp. Explanation of symbols 1...Curve showing the decomposition rate of the oxazole derivative () used in Example 1, 2...Curve showing the decomposition rate of the oxazole derivative () used in Example 2, 3...Oxazole used in Example 3 Curve showing the decomposition rate of the derivative (2), 4...Curve showing the decomposition rate of the oxazole derivative (2) used for comparison.

Claims (1)

[Claims] 1 General formula () An electrophotographic photoreceptor comprising an oxazole derivative represented by the formula (wherein R ₁ , R ₂ , R ₃ and R ₄ represent an alkyl group and may be the same or different). 2 A conductive support contains a charge generating substance and a charge transporting substance, and the charge transporting substance has the above general formula ().
The electrophotographic photoreceptor according to claim 1, which is an oxazole derivative represented by: 3. The electrophotographic photoreceptor according to claim 2, wherein the charge generating material and the charge transporting material are each contained in separate layers.