JPH0449585B2 - - Google Patents

Description

[Detailed description of the invention]

TECHNICAL FIELD The present invention relates to a novel disazo compound and a method for producing the same. 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. A photoreceptor is formed with a charge transport layer (usually, this charge transport layer is composed of a charge transport substance and a binding resin) that can efficiently inject and transfer the charge transport material. Conventionally, as a disazo compound used in this type of photoreceptor, for example,
Benzidine-based disazo compounds described in JP-A-47-37543 and JP-A-52-55643, and stilbene-based disazo compounds described in JP-A-52-8832 are known. There is. However, conventional laminated photoreceptors using disazo compounds generally have low sensitivity, and the visible wavelength range extends from approximately 450 to 700 nm, which makes it difficult to reproduce images of red originals. It was a bad idea. 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, This type of photoreceptor 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 800 nm), so it is difficult to copy images of red originals. The reproducibility is also excellent. Another object of the present invention is to provide a method for producing the above-mentioned disazo compound. Structure: One of the aspects of the present invention is a novel disazo compound represented by the general formula (). (In the above formula, R ₁ and R ₂ are hydrogen atoms, lower alkyl groups, aralkyl groups, unsubstituted or aromatic hydrocarbon groups substituted with lower alkyl groups, lower alkoxy groups, nitro groups or chlorine atoms, (Represents a thienyl group or carbazolyl group substituted with a substituted or lower alkyl group, and R ₁ and R ₂ may be the same or different.) Specific examples of the aromatic hydrocarbon group represented by R ₁ and R ₂ in this general formula Examples include phenyl, naphthyl, anthryl and the like. Another aspect of the present invention is the formula () By diazotizing 2,7-diaminoanthraquinone represented by the general formula () (In the formula, Y represents an anionic functional group.) Then, this tetrazonium salt and the general formula () (In the above formula, R ₁ and R ₂ have the same meanings as above.) General formula () characterized by reacting with a coupler represented by (In the above formula, R ₁ and R ₂ have the same meanings as above.) This is a method for producing a disazo compound represented by the following. In this production method, 2,7-diaminoanthraquinone is diazotized by adding sodium sulfite in an inorganic acid such as hydrochloric acid or sulfuric acid at a temperature of -10°C to 50°C. This diazotization reaction takes approximately 30 minutes to 30 minutes.
It will be completed in time. Furthermore, it is desirable to add, for example, hydroborofluoric acid or an aqueous sodium borofluoride solution to the reaction mixture to precipitate the tetrazonium salt, and then use it in the next reaction after crystallizing it. Next, this tetrazonium salt is reacted with a coupler represented by the general formula () to cause a coupling reaction. In reality, this reaction is carried out by dissolving a tetrazonium salt and coupler in an organic solvent such as N,N-dimethylformamide (DMF) or dimethyl sulfoxide, and adding sodium acetate at about -10°C to 40°C. This is done by dropping an aqueous calcareous solution such as an aqueous solution. This reaction is complete in approximately 5 minutes to 3 hours. After completion of the reaction, the precipitated crystals are collected 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. Examples of the production of the disazo compound of the present invention produced in this manner are as follows. Production Example 4.76g of 2,7-diaminoanthraquinone was dissolved in 40ml of concentrated sulfuric acid under ice cooling. Add this solution to 100% cold water.
Further, a solution prepared by dissolving 30 gr of sodium sulfite in 10 ml of water was added dropwise to this mixture at 0 to 5°C over a period of about 20 minutes. The reaction mixture was stirred for a further 40 minutes at approximately 0°C, then washed with 400 ml of cold water.
After injecting into the solution and then separating a small amount of insoluble matter,
50 ml of 42% HBF ₄ was added to the solution. Collect the deposited precipitate, wash 100 ml with cold water, further wash with 100 ml of methanol, and then dry to obtain 7.16 g of light brown anthraquinone-2,7-bisdiazonium bistetrafluoroborate.
(82.1%). Infrared absorption spectrum (KBr tablet method) νN ₂ 2280cm ^-1 νco 1680cm ^-1 Elemental analysis value C ₁₄ H ₆ N ₄ O ₂ B ₂ F ₈ Actual value Calculated value N% 13.03 13.22 In addition, the infrared spectrum is shown in Figure 1. An absorption spectrum diagram is shown. Then, the tetrazonium salt obtained in this way
Dissolve 2.18gr (0.0050mol) and 0.01mol of Kappler represented by the general formula () in 300ml of DMF,
A solution of 1.64 gr of sodium acetate dissolved in 14 ml of water was added dropwise to this at room temperature over about 15 minutes. After the addition was completed, the mixture was further stirred at the same temperature for 2 hours, and then the precipitated crystals were collected. The obtained coarse crystal cake
After dispersing in 300 ml of DMF and stirring at 80°C for 2 hours, crystals were collected again, and this operation was repeated twice. Thereafter, the crystals were washed with water and dried to obtain the disazo compound of the present invention. Tables 1 to 3 show examples of the disazo compounds of the present invention synthesized according to the above production examples.

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[Table] These new disazo compounds are red to reddish-purple powders at room temperature. Figures 2 to 18 show infrared absorption spectra (KBr tablet method) of typical disazo compounds of the present invention. Figure 2... Compound No. 1 Figure 3... Compound No. 2 Figure 4... Compound No. 3 Figure 5... Compound No. 4 Figure 6... Compound No. 5 Figure 7... Compound No. 6 Figure 8... Compound No. 7 Figure 9... Compound No. 8 Figure 10... Compound No. 9 Figure 11... Compound No.
10 Figure 12... Compound No. 11 Figure 13... Compound No.
12 Figure 14... Compound No. 13 Figure 15... Compound No.
14 Figure 16... Compound No. 22 Figure 17... Compound No.
23 Figure 18... Compound No. 24 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, and this point will be clarified. For this purpose, specific usage examples are shown below.
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. 12 of the present invention, a tetrahydrofuran solution (solid content concentration 2) of polyester resin (Vylon 200, manufactured by Toyobo Co., Ltd.)
%) 1260 parts by weight, and tetrahydrofuran 3700
The weight parts 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 to a thickness of approximately 1 μm.
A charge generation layer was formed. On the other hand, 2 parts by weight of 9-ethylcarbazole-3-aldehyde-1-methyl-1-phenylhydrazone, polycarbonate resin (Panlinet K1300, manufactured by Teijin Kasei Ltd.)
After mixing and dissolving 2 parts by weight and 16 parts by weight of tetrahydrofuran to form a solution, this was applied onto the charge generation layer using a doctor blade and heated at 80°C for 2 minutes.
Then, the mixture was dried at 100° C. for 5 minutes to form a charge transport layer having a thickness of about 20 μm, thereby producing a laminated photoreceptor (A) shown in FIG. 19. 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(, a stilbene-based disazo compound described in JP-A-52-8832). Each photoreceptor was prepared in the same manner except that 2-hydroxy-3-phenylcarbamoyl-1-naphthylazo)stilbene was used.
(B) and photoreceptor (C) were prepared. 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 surface potential was then dark decayed for 20 seconds in a dark place, and the surface potential was measured and expressed as Vpo (volts). Then,
The photosensitive layer is irradiated with light from a tungsten lamp so that the surface has an illuminance of 4.5 lux, and the time (seconds) until the surface potential becomes 1/2 of Vpo is determined, and the exposure amount E1/2 (lux seconds). Similarly, find the time (seconds) until it becomes 1/5 and 1/10 of Vpo, and calculate the exposure amount E1/5 (lux seconds) and E1/10.
(Lutux seconds) was calculated. The results are shown in Table 4.

[Table] As is clear from the results in Table 4, the photoreceptor (A) using the disazo compound of the present invention has higher sensitivity than the photoreceptors (B) and (C) using the conventional disazo compound. It turns out that it is expensive. From what has been described above, it can be understood that the disazo compound of the present invention is an extremely effective material. Further, the disazo compound of the present invention can be used as a charge generating substance in an electrophotographic photoreceptor having a single-layer type photosensitive layer in which a charge generating substance and a charge transporting substance are dispersed in the resin, and also as a photoconductive substance in the resin. It is also useful as a photoconductive material in an electrophotographic photoreceptor having a photosensitive layer in which a substance is dispersed.

[Brief explanation of the drawing]

Figure 1 is an infrared absorption spectrum diagram (KBr tablet method) of the tetrazonium salt according to the present invention, and Figures 2 to 18 are infrared absorption spectrum diagrams (KBr tablet method) of typical disazo compounds of the present invention. . FIG. 19 is an enlarged sectional view of an electrophotographic photoreceptor according to the present invention, in which 11 is a polyester base, 2 is a
2 is an aluminum vapor deposited film, 33 is a charge generation layer, 4
4 represents a charge transport layer.

Claims (1)

[Claims] 1 General formula () (In the above formula, R ₁ and R ₂ are hydrogen atoms, lower alkyl groups, aralkyl groups, unsubstituted or lower alkyl groups, lower alkoxy groups, nitro groups, or aromatic hydrocarbon groups substituted with chlorine atoms, unsubstituted or a thienyl group or carbazolyl group substituted with a lower alkyl group, and R ₁ and R ₂ may be the same or different. 2 formula () 2,7-diaminoanthraquinone represented by is disazotized to form the general formula () (In the formula, Y represents an anionic functional group.) Then, this tetrazonium salt and the general formula () (In the above formula, R ₁ and R ₂ are hydrogen atoms, lower alkyl groups, aralkyl groups, unsubstituted or lower alkyl groups, lower alkoxy groups, nitro groups, or aromatic hydrocarbon groups substituted with chlorine atoms, unsubstituted or a thienyl group or carbazolyl group substituted with a lower alkyl group, and R ₁ and R ₂ may be the same or different.) (In the above formula, R ₁ and R ₂ have the same meanings as above.) A method for producing a disazo compound represented by the following.