JPH0466905B2 - - Google Patents

Description

[Detailed description of the invention]

TECHNICAL FIELD The present invention relates to novel disazo compounds. Prior Art Conventionally, certain disazo compounds have been used in laminated photoreceptors, which are one form of electrophotographic photoreceptor.
It is known to be effective as a charge-generating pigment used in a charge-generating layer. The laminated photoreceptor here refers to a charge-generating pigment that has the ability to generate charge carriers when exposed to light on a conductive support.
A charge generation layer is formed as a thin layer by a suitable method such as vacuum evaporation, coating of a pigment solution, or coating of a dispersion of fine pigment particles in a resin solution, and the charge carriers generated in the charge generation layer are deposited thereon. It is a photoreceptor on which a charge transporting layer (generally, this charge transporting layer is composed of a charge transporting substance and a binder resin) is formed to which charge transporting material can be efficiently injected and the charge transporting material can be transferred. Conventionally, disazo compounds used in this type of photoreceptor include benzidine-based disazo compounds described in JP-A-47-37543 and JP-A-52-55643, and JP-A-52-55643. Stilbene-based disazo compounds described in Publication No. 52-8832 are known. However, conventional laminated photoreceptors using disazo compounds generally have low sensitivity, and
The photosensitive wavelength range in the visible range extends from approximately 450 to 700 nm, and the image reproducibility of red originals was poor due to the photosensitive wavelength characteristics. Therefore, when this photoreceptor is mounted, there is a disadvantage in the design of the copying machine because it is necessary to use a filter that cuts out red light. Purpose An object of the present invention is to provide a novel disazo compound that is effective in electrophotographic photoreceptors, particularly in the laminated type photoreceptor mentioned above.
The laminated photoreceptor using the disazo compound of the present invention has higher sensitivity than conventional photoreceptors using disazo compounds, and its sensitivity wavelength range is on the short wavelength side of the visible range (approximately 450 to 600 nm). Since it is only available in Japan, the reproduction of reproduced images of red originals is also excellent. Structure The present invention is a novel disazo compound represented by the general formula (). [In the formula, A is or (wherein, R represents an alkyl group such as methyl, ethyl, propyl, butyl, an alkoxy group, a nitro group, a halogen, a cyano group, or a halomethyl group, and n is 0, 1 or an integer, and n is 2
R may be the same or different groups. ). ] The disazo compound represented by the formula () of the present invention is useful as a charge-generating substance for a laminated electrophotographic photoreceptor as described above, but it is also possible to disperse a charge-generating substance and a charge-transporting substance in the resin. It is useful as a charge-generating material in an electrophotographic photoreceptor having a single-layer type photoreceptor, and as a photoconductive material in an electrophotographic photoreceptor having a photosensitive layer in which a photoconductive substance is dispersed in a resin. . The disazo compound of the present invention can be obtained by reducing 2,7-dinitroxanthone and then diazotizing it to obtain the disazo compound of the general formula () The diazotization can be carried out by using a tetrazonium salt represented by the formula (wherein, X represents an anionic functional group) and allowing this diazotization reaction solution to act on a coupler as it is. Alternatively, for example, hydroborofluoric acid or an aqueous sodium borofluoride solution may be added to the diazotization reaction solution to precipitate the tetrazonium salt of the above general formula (), the tetrazonium salt may be isolated, and the coupler may be reacted with the tetrazonium salt. It can also be obtained by In this reaction, a tetrazonium salt and a coupler are mixed and dissolved in an organic solvent such as N,N-dimethylformamide (DAF) or dimethyl sulfoxide (DMSO), and the mixture is heated at about -10°C to 40°C.
This is carried out by dropping an alkaline aqueous solution such as an aqueous sodium acetate solution at ℃. This reaction is complete in approximately 5 minutes to 3 hours. After completion of the reaction, the precipitated crystals are collected by filtration and purified by an appropriate method (for example, washing with water and/or an organic solvent, recrystallization method, etc.) to complete the production of the disazo compound of the present invention. The coupler used in the above production is a compound represented by the following general formula (), (), () or (). or A compound represented by (R and n have the same meanings as above). Note that the tetrazonium salt represented by the general formula (), which is a raw material for this production, can be obtained, for example, by reducing 2,7-dinitroxanthone and then diazotizing it. 2,7-dinitroxanthone and 2,7-diaminoxanthone are described, for example, in [AAColdberg and HAWalker,
Journal of Chemical Society, 1953, 1348
(1953)], xanthone is nitrated in fuming nitric acid to give 2,7-dinitroxanthone, which is reduced to 2,7-dinitroxanthone in hydrochloric acid using a reducing agent such as stannous chloride. 7-diaminoxanthone is obtained. This reduction reaction is 95-100
It is completed in about 3 hours at a temperature of ℃. Diazotization of 2,7-diaminoxatone is carried out, for example, by adding sodium nitrite in an inorganic acid such as hydrochloric acid or sulfuric acid at -10°C to 20°C. This diazotization reaction is completed in approximately 30 minutes to 3 hours. Further, by adding, for example, an aqueous sodium borofluoride solution to this diazotization reaction solution, a tetrazonium salt can be obtained. The novel disazo compound of the present invention is a colored crystal at room temperature, and specific examples thereof are shown in Table 1 below along with melting point, elemental analysis values, and infrared absorption spectrum data.
It was shown to.

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[Table] Production example 1 (Production of tetrazonium salt) Into hydrochloric acid consisting of 224 ml of water and 224 ml of concentrated hydrochloric acid,
Add 29.18g of 7-diaminoxanthone and heat to approximately 60°C.
After heating for 1 hour, cool to -3℃,
Next, add 18.7g of sodium nitrite to this and 90ml of water.
was added dropwise over 50 minutes at a temperature of -3°C to 0°C. After stirring at the same temperature for 30 minutes, 150 ml of 42% borofluoric acid was added to the reaction solution, and the precipitated crystals were separated, washed with water, and dried.
47.13 g (yield 86.1%) of pale yellow crystals of tetrazonium difluoroborate were obtained. Decomposition point 145℃
As described above, the infrared absorption spectrum (KBr tablet method) is as shown in FIG. 1, and an absorption band based on N ₂ was observed at 2280 cm ^-1 and an absorption band based on C=O was observed at 1685 cm ^-1 . Production Example 2 (Production of Disazo Compound No. 1) 5.0 g of the tetrazonium salt obtained in Production Example 1 and 6.25 g of 2-hydroxy-3-naphthoic acid anilide (twice the mole of the tetrazonium salt) as a coupling component were cooled. Dissolved in 700 ml of N,N-dimethylformamide and added 4.0 g of sodium acetate.
and 35 ml of water at a temperature of 5 to 10°C for 20
The mixture was added dropwise over a period of minutes, and after cooling was discontinued, the mixture was further stirred at room temperature for 3 hours. Thereafter, the formed precipitate was collected, washed three times with 700 ml of N,N-dimethylformamide heated to 80°C, then washed twice with 700 ml of water, dried at 80°C under a reduced pressure of 2 mmHg, and then Compound No. 1 disazo compound 8.2g (yield
90.0%). The appearance of this disazo compound is a red powder, and the infrared absorption spectrum (KBr
Tablet method) is shown in Figure 2. Production Examples 3 to 40 (Production of Disazo Compounds No. 2 to 39) In the production of the disazo compound of Compound No. 1 of Production Example 2, the same method as Production Example 2 was used except that the compounds in Table 2 below were used as coupling components. Disazo compounds of Compound Nos. 2 to 39 shown in Table 1 were produced. In addition, among the disazo compounds of the present invention, the infrared absorption spectra of typical ones are
It is shown in Figure 9. Figure 3... Compound No. 13 Figure 4... Compound No. 16 Figure 5... Compound No. 31 Figure 6... Compound No. 32 Figure 7... Compound No. 33 Figure 8... Compound No. 34 Figure 9 Figure…Compound No.35

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[Table] Effects As mentioned above, the disazo compound of the present invention is effective as a photosensitive material for electrophotographic photoreceptors, especially as a charge-generating material for laminated photoreceptors. A specific usage example is shown.
Furthermore, in order to clarify the inventive step of the present invention, a comparison with conventional disazo compounds is also shown. Application example: 76 parts by weight of disazo compound No. 13 of the present invention, polyester resin (Vylon 200 manufactured by Toyobo Co., Ltd.)
Tetrahydrofuran solution (solid content concentration 2%)
1,260 parts by weight and 3,700 parts by weight of tetrahydrofuran were pulverized and mixed in a ball mill, and the resulting dispersion was applied onto the aluminum surface of an aluminum-deposited polyester base (conductive support) using a doctor blade, and air-dried. A charge generation layer with a thickness of about 1 μm was formed. Separately, 2 parts by weight of 9-ethylcarbazole-3-aldehyde 1-methyl-1-phenylhydrazone, 2 parts by weight of polycarbonate resin (Panlite K1300, manufactured by Teijin Kasei Ltd.) and 16 parts by weight of tetrahydrofuran were mixed and dissolved. After that, this was applied onto the charge generation layer using a doctor blade and heated at 80°C for 2 minutes and then at 105°C.
The mixture was dried for 5 minutes at 0.degree. C. to form a charge transport layer with a thickness of about 20 .mu.m, thereby producing a laminated photoreceptor (A) shown in No. 10. For comparison, in accordance with the above procedure for producing the photoreceptor, instead of the disazo compound of the present invention, the benzidine-based disazo compound disclosed in JP-A-45-37543 and JP-A-52-55643 was used. The compound 4,4'-bis(2-
Hydroxy-3-phenylcarbamoyl-1-
naphthylazo)-3,3'-dichlorodiphenyl and 4,4'-bis(2-hydroxy-3-phenylcarbamoyl-), which is a stilbene-based disazo compound described in JP-A-52-8832. A photoreceptor (B) and a photoreceptor (C) were prepared in exactly the same manner except that 1-naphthylazo)stilbene was used. Photoreceptors (A), (B) and (C) created in this way
The electrostatic properties were measured using a commercially available electrostatic copying paper testing device (manufactured by Kawaguchi Electric Seisakusho, Model SP-428). That is, first, a -6KV corona discharge is applied to the photoreceptor for 20 seconds to negatively charge it, and the surface potential at that time is measured to find Vdo (volts).
The sample was left in the dark for 20 seconds to allow it to decay in the dark, and the surface potential at that time was measured and expressed as Vpo (volts). Then, from the tungsten lamp, the surface is illuminated with an illuminance of 20
The photosensitive layer was irradiated with light so that the surface potential became 1/2 of Vpo, and the time (seconds) until the surface potential became 1/2 of Vpo was determined, and the exposure amount E1/2 (lux/second) was determined.
Similarly, the time (seconds) until it becomes 1/5 and 1/10 of Vpo
Find the exposure amount E1/5 (lux seconds) and E
1/10 (lux/second) was calculated. This result is shown in Table 3.
It was shown to.

[Table] In order to investigate the sensitive wavelength range of the photoreceptor (A) according to the present invention, the spectral sensitivity was measured by the following measurement procedure. First, the photoreceptor is charged to a surface potential of -800 volts or more by corona discharge in a dark place, dark decayed until the surface potential reaches -800 volts, and when the surface potential reaches -800 volts, the monochromator The photoreceptor was irradiated with monochromatic light of 1 μW/cm ² that was spectrally separated using a photoreceptor. Then, the time (seconds) until the surface potential attenuated to -400V was determined, and the half-reduced exposure amount (μW·sec/cm ³ ) was calculated. On the other hand, the potential difference actually obtained by exposure is determined by subtracting the potential attenuation due to dark decay from the apparent potential difference of 400 volts obtained by exposure, and the light decay rate is calculated from this potential difference and the above-mentioned halved exposure amount. (Volt・^cm2・
μW ^-1・sec ^-1 ) was calculated and defined as the sensitivity. This spectral sensitivity curve is shown in FIG. As is clear from the results in Table 3, the photoreceptor (A) using the disazo compound of the present invention has extremely high sensitivity compared to photoreceptors (B) and (C) using conventional disazo compounds. I understand. Moreover, from FIG. 11, the photoreceptor (A) using the disazo compound of the present invention has a photosensitive wavelength range of approximately
It turns out that it is 450 to 600 nm, and from this,
It can be seen that the image reproducibility of red originals is good.

[Brief explanation of drawings]

FIG. 1 is an infrared absorption spectrum diagram (KBr tablet method) of the tetrazonium salt compound of Example.
Figures 2 to 9 are infrared absorption spectra of typical disazo compounds of the present invention (KBr tablet method).
It is. FIG. 10 is an enlarged sectional view of an electrophotographic photoreceptor according to the present invention, in which 11 represents a polyester base, 22 represents an aluminum vapor deposited film, 33 represents a charge generation layer, and 44 represents a charge transport layer. FIG. 11 is a spectral sensitivity curve of the electrophotographic photoreceptor according to the present invention.

Claims (1)

[Claims] 1 General formula () [In the formula, A is or (However, R represents an alkyl group, an alkoxy group, a nitro group, a halogen, a cyano group, or a halomethyl group, and n is an integer of 0, 1 or 2, and when n is an integer of 2, R may be the same or different groups.)
represents. ] A novel disazo compound represented by