JPH0524184B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a novel disazo compound and a method for producing the same. It has been known that certain disazo compounds are effective as charge-generating pigments used in charge-generating layers of laminated photoreceptors, which are one form of electrophotographic photoreceptors. The laminated photoreceptor referred to herein means that a charge-generating pigment having the ability to generate charge carriers by light is applied onto a conductive support by an appropriate method such as vacuum evaporation, coating of a pigment solution, or resin solution. A charge generation layer is formed as a thin layer by applying a dispersion liquid containing fine pigment particles dispersed thereon, and the charge carriers generated in the charge generation layer can be efficiently injected onto the layer, and the charge carriers can be transferred. It is a photoreceptor on which a charge transport layer (usually this charge transport layer consists of a charge transport substance and a binder resin) is formed. Conventionally, as a disazo compound used in this type of photoreceptor, for example, JP-A-47
Benzidine-based disazo compounds described in JP-A-37543 and JP-A-52-55643, and stilbene-based disazo compounds described in JP-A-52-8832 are known. 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. 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,
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. Another object of the present invention is to provide a method for producing the above-mentioned disazo compound. One aspect of the present invention is a novel disazo compound represented by the general formula (). General formula () [In the formula, A is

[Formula] (In the formula, R ₁ to _{R 4} are as follows, and when R ₂ is OCH ₃ , R ₁ , R ₃ , and R ₄ are H;
When R ₂ is CH ₃ R ₁ , R ₃ , R ₄ are H; When R ₃ is CH ₃
R ₁ , R ₂ , R ₄ are H; when R ₁ is Cl, R ₂ , R ₃ , R ₄ are H;
When R ₂ is Cl, R ₁ , R ₃ , R ₄ are H; When R ₁ is Br, R ₂ ,
R ₃ and R ₄ are H; when R ₂ is Br, R ₁ , R ₃ and R ₄ are H; R ₃
When is Br, R ₁ , R ₂ , R ₄ are H; When R ₂ is F, R ₁ , R ₃ ,
R ₄ is H; when R ₂ is I, R ₁ , R ₃ , R ₄ are H; R ₂ is CF ₃
When R ₁ , R ₃ , R ₄ are H; When R ₁ is NO ₂ , R ₂ , R ₃ , R ₄
is H; when R ₂ is NO ₂ , R ₁ , R ₃ and R ₄ are H; R ₂ is CN
When R ₁ , R ₃ and R ₄ are H; When R ₁ and R ₄ are Cl, R ₂ and R ₃ are H; When R ₁ is CH ₃ and R ₄ is Cl, R ₂ and R ₃ are H. show. ) or

[Formula] is shown. ] It is expressed as . 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.) (In the formula, R ₁ , R ₂ , R ₃ , and R ₄ are the same as above) or

General formula () characterized by reacting with [Formula] This is a method for producing a disazo compound represented by the formula (where A is the same as above). The tetrazonium salt compound represented by the formula () is a useful intermediate for disazo compounds, and when combined with a suitable coupler, it has an anthoquinone skeleton and its 2
A wide variety of disazo compounds having azo groups at the 7- and 7-positions can be synthesized. This disazo compound is expected to be used as a photoconductive material for electrophotographic photoreceptors, particularly as a charge generating material. Typical examples of anionic functional groups in the tetrazonium salt compound of general formula () are Cl, Br,
I, OBF ₄ , PF ₆ ,

[Formula] ClO ₄ OSO ₄ 2 ,

[Formula] Examples include AsF ₆ and SbF ₆ , with BF ₄ being preferred. 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 useful as a charge-generating substance and a charge-transporting substance dispersed in the resin. It is useful as a charge-generating material in an electrophotographic photoreceptor having a single-layer type photosensitive layer, and as a photoconductive material in an electrophotographic photoreceptor having a photosensitive layer in which a photoconductive substance is dispersed in a resin. The tetrazonium salt of the general formula () is a new compound, ethyl, and its production method is to diazotize 2,7-diaminoanthraquinone, for example, by diazotizing it with sodium nitrite in an inorganic acid such as hydrochloric acid or sulfuric acid at -10°C to 20°C. This is done by adding at ℃. This diazotization reaction takes approximately 30 minutes to 30 minutes.
It will be completed in time. Furthermore, in this diazotization reaction solution,
For example, a tetrazonium salt can be obtained by adding hydroborofluoric acid or an aqueous sodium borofluoride solution. The production of the disazo compound of the general formula () is as follows:
The above diazotization reaction solution can be directly applied to a coupler, or it can be carried out by adding, for example, hydroborofluoric acid or an aqueous sodium borofluoride solution to the diazotization reaction solution to form the general formula (). It can also be obtained by isolating the tetrazonium salt by precipitating it as a tetrazonium salt and then reacting it with a coupler of general formula ().
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 then heating the mixture at a temperature of about -10°C to 40°C.
This is done by dropping an aqueous alkaline solution such as an aqueous sodium acetate solution into the solution. This reaction is complete in approximately 5 minutes to 3 hours. After the reaction is complete,
The production of the disazo compound is completed by collecting the precipitated crystals and purifying them by an appropriate method (for example, washing with water and/or an organic solvent, recrystallization method, etc.). Examples of the production of the tetrazonium salt and 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.
ml, and then add a solution of 3.0 gr of atrium nitrite dissolved in 10 ml of water to this mixture at 0-5℃.
It took about 20 minutes to add the solution dropwise. The reaction mixture was stirred for an additional 40 minutes at approximately 0°C, then cooled to 400°C with cold water.
After a small amount of insoluble material was removed, 50 ml of 42% HBF ₄ was added to the solution. After removing the precipitate and washing it with 100ml of cold water,
Further washing was performed with 100ml of methanol, and then,
Dried, pale brown anthraquinone-2,7-bisdiazonium bistetrafluoroborate 7.16
g (82.1%). Infrared absorption spectrum (KBr tablet method) νH ₂ 2280cm ^-1 νco 1680cm ^-1 Elemental analysis value C ₁₄ H ₆ N ₄ O ₂ B ₂ F As ₈ Actual value Calculated value N% 13.03 13.22 In addition, Fig. 1 shows the infrared absorption spectrum. A diagram was shown. Then, the tetrazonium salt obtained in this way
2.18gr (0.005mol) and 0.01mol of the coupler represented by the general formula () were dissolved in 300ml of DMF, and a solution of 1.64gr of sodium acetate dissolved in 14ml of water was added dropwise thereto over about 15 minutes at room temperature. After the dripping is finished,
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. Tables 1 and 2 show examples of the disazo compounds of the present invention synthesized according to the above production examples.

【table】

【table】

[Table] These new disazo compounds are red to reddish-purple powders at room temperature. Figures 2 to 13 show infrared absorption spectra (KBr tablet method) of typical disazo compounds of the present invention. Figure 2… Compound No. 3 Figure 3… Compound No. 6 Figure 4… Compound No. 7 Figure 5… Compound No. 8 Figure 6… Compound No. 9 Figure 7… Compound No. 11 Figure 8 Figure… Compound No. 12 Figure 9… Compound No. 14 Figure 10… Compound No. 16 Figure 11… Compound No. 17 Figure 12… Compound No. 18 Figure 13… Compound No. 20 Disazo of the present invention As mentioned above, the compound is effective as a photosensitive material for electrophotographic photoreceptors, particularly as a charge-generating material for laminated photoreceptors, and in order to clarify this point, 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, 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 heated at 100°C.
A charge transport layer with a thickness of about 20 μm was formed by drying at ℃ for 5 minutes, and the laminated photoreceptor (A) shown in Figure 20 was formed.
It was created. 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'- which is a stilbene-based disazo compound described in JP-A-52-8832.
Each photoreceptor was prepared in the same manner except that bis(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 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, find the time (seconds) until it becomes 1/5 and 1/10 of Vpo, and calculate the exposure amount E1/5 (lux seconds) and E1/1.
0 (lux seconds) 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 ² ) 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・cm ²・
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, 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. 15, 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 a tetrazonium salt compound of a production example.
Figures 2 to 13 are infrared absorption spectra of typical disazo compounds of the present invention (KBr tablet method).
It is. FIG. 14 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. 15 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 [Formula] (In the formula, R ₁ to ^{R 4} are as follows, and when R ₂ is OCH ₃ , R ₁ ,
R ₃ and R ₄ are H; when R ₂ is CH ₃ , R ₁ , R ₃ and R ₄ are H; R ₃
When is CH ₃ , R ₁ , R ₂ , R ₄ are H; When R ₁ is Cl, R ₂ ,
R ₃ and R ₄ are H; when R ₂ is Cl, R ₁ , R ₃ and R ₄ are H; R ₁ is
When R 2 is Br, R ₂ , R ₃ , R ₄ are H; when R ₂ is Br, R ₁ , R ₃ ,
R ₄ is H; when R ₃ is Br, R ₁ , R ₂ , R ₄ are H; R ₂ is F
When R ₁ , R ₃ and R ₄ are H; When R ₂ is I, R ₁ , R ₃ and R ₄ are H; When R ₂ is CF ₃ , R ₁ , R ₃ and R ₄ are H; R ₁ When is NO ₂ , R ₂ , R ₃ and R ₄ are H; When R ₂ is NO ₂ , R ₁ , R ₃ and R ₄ are H; When R ₂ is CN, R ₁ , R ₃ and R ₄ are H. ;R ₁ and R ₄ are Cl
When R ₂ and R ₃ are H; when R ₁ is CH ₃ and R ₄ is Cl, R ₂ and R ₃
indicates H. ) or [formula]. ] A disazo compound represented by 2 formula () By diazotizing 2,7-diaminoanthraquinone represented by the general formula () (in the formula, Y represents an anionic functional group), and then this tetrazonium salt and In the formula, R ₁ to _{R 4} are as follows, and when R ₂ is OCH ₃ , R ₁ ,
R ₃ and R ₄ are H; when R ₂ is CH ₃ , R ₁ , R ₃ and R ₄ are H; R ₃
When is CH ₃ , R ₁ , R ₂ , R ₄ are H; When R ₁ is Cl, R ₂ ,
R ₃ and R ₄ are H; when R ₂ is Cl, R ₁ , R ₃ and R ₄ are H; R ₁ is
When R 2 is Br, R ₂ , R ₃ , R ₄ are H; when R ₂ is Br, R ₁ , R ₃ ,
R ₄ is H; when R ₃ is Br, R ₁ , R ₂ , R ₄ are H; R ₂ is F
When R ₁ , R ₃ and R ₄ are H; When R ₂ is I, R ₁ , R ₃ and R ₄ are H; When R ₂ is CF ₃ , R ₁ , R ₃ and R ₄ are H; R ₁ When is NO ₂ , R ₂ , R ₃ and R ₄ are H; When R ₂ is NO ₂ , R ₁ , R ₃ and R ₄ are H; When R ₂ is CN, R ₁ , R ₃ and R ₄ are H. ;R ₁ and R ₄ are Cl
When R ₂ and R ₃ are H; when R ₁ is CH ₃ and R ₄ is Cl, R ₂ and R ₃
indicates H. ) or a general formula () characterized by reacting with a coupler of [formula] [In the formula, A is [Formula] or [Formula] (wherein R ₁ , R ₂ , R ₃ , and R ₄ are the same as above)] A method for producing a disazo compound.