JPH0447714B2 - - 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. 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, 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 the above-mentioned laminated type photoreceptor. 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 lower alkyl groups,
Represents an aralkyl group or a phenyl group. ) Specific examples of aromatic rings and heterocycles in this general formula include benzene ring, naphthalene ring, anthracene ring, pyrene ring, thiophene ring, carbazole ring, etc. Substituents for these rings include lower alkyl groups, lower Examples include alkoxy groups, halogens, and nitro groups. Another aspect of the present invention is the formula () 2,6-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 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 cis-sazo compound represented by the following. In this production method, the diazotization of 2,6-diaminoanthraquinone is carried out by adding sodium nitrite to it in an inorganic acid such as hydrochloric acid or sulfuric acid at -10°C to 50°C. . This diazotization reaction is completed in approximately 30 minutes to 3 hours. 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 mixture of tetrazonium salt and coupler in an organic solvent such as N,N-dimethylformamide (DMF) or dimethyl sulfoxide, and adding sodium acetate to the solution at about -10°C to 40°C. This is done by dropping an alkaline aqueous 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 purified in this manner are as follows. Production example 2,6-diaminoanthraquinone [Aldrich Chemical Company
Co., MilwaKee)] 14.3g (0.06mol) and 36%
9.0 g of sodium nitrite in a mixture with 155 ml of hydrochloric acid
A solution prepared by dissolving this in 30 ml of water was added dropwise at -5°C to 0°C over about 20 minutes. After the dropwise addition was completed, the mixture was stirred for another 2 hours at the same temperature, poured into cold water from step 3, filtered to remove a small amount of insoluble matter, and 40 ml of 42% hydroborofluoric acid was added to the liquid. The precipitated crystals were collected, washed with about 50 ml of methanol, and dried to produce anthraquinone as pale brown crystals.
22.6 g (86.3%) of 2,6-bisdiazonium bistetrafluoroborate was obtained. Infrared absorption spectrum (KBr tablet method) νN ₂ 2310cm ^-1 νCO 1695cm ^-1 Then, the tetrazonium salt obtained in this way
2.18 g (0.05 mol) and 0.01 mol of the coupler represented by the general formula () were dissolved in 300 ml of DMF, and a solution of 1.64 g of sodium acetate dissolved in 14 ml of water was added dropwise thereto over about 15 minutes at room temperature. After finishing dropping,
After further stirring at the same temperature for 2 hours, 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. Table 1 shows the disazo compounds of the present invention synthesized according to the above production examples.

[Table] These new disazo compounds are red to reddish-purple powders at room temperature. 1 to 3 show infrared absorption spectra (KBr tablet method) of typical disazo compounds of the present invention. Figure 1: Compound No. 1 Figure 2: Compound No. 2 Figure 3: Compound No. 3 Effects As mentioned above, the disazo compound of the present invention can be used as a photosensitive material for electrophotographic photoreceptors, especially for laminated type photoreceptors. It is effective as a charge-generating material in the body, and a laminated photoreceptor using this material has higher sensitivity than a photoreceptor using conventional disazo compounds, and its sensitivity wavelength range is on the short wavelength side of the visible range. (approximately 450-600nm)
Therefore, the reproducibility of copied images of red originals is also excellent. To clarify this point, specific application 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. 2 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
Parts by weight 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, air-dried, and a powder with a thickness of about 1 μm was applied. A charge generation layer was formed. Meanwhile, 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 tetrahydrafuran were mixed and dissolved. This was applied onto the charge generation layer using a doctor blade and dried at 80°C for 2 minutes and then at 100°C for 5 minutes to form a charge transport layer with a thickness of about 20 μm. A laminated type photoreceptor A shown in FIG. 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. Photoconductor B and photoconductor 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, the surface is illuminated by a tungsten lamp.
The photosensitive layer is irradiated with light so that it becomes 4.5 lux,
Time (seconds) until the surface potential becomes 1/2 of Vpo
was determined and set as the exposure amount E1/2 (lux seconds).
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. Table this result.
Shown in 2.

[Table] As is clear from the results in Table 2, photoreceptor A using the disazo compound of the present invention has higher sensitivity than photoreceptors B and C using conventional disazo compounds. From what has been described above, it will 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]

Figures 1 to 3 are infrared absorption spectra of typical disazo compounds of the present invention (KBr tablet method).
It is. FIG. 4 is an enlarged cross-sectional view of the electrophotographic photoreceptor according to the present invention, in which 11 is a polyester base;
22 is an aluminum vapor deposited film, 33 is a charge generation layer,
44 represents a charge transport layer.

Claims (1)

[Claims] 1 General formula () (In the above formula, R ₁ and R ₂ are lower alkyl groups,
Represents an aralkyl group or a phenyl group. ) A disazo compound represented by 2 formula () 2,6-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 lower alkyl groups,
Represents an aralkyl group or a phenyl group. ) A 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.) A method for producing a cis-sazo compound represented by the following.