JPH0586003A - Azo-based compound and diazonium salt - Google Patents

Abstract

PURPOSE:To obtain a new azo-based compound suitable as various photosensitive materials such as charge producing materials in electrophotographic photoreceptors, pigments, solar cells, etc., and a new diazonium salt as an intermediate suitable for its production. CONSTITUTION:An azo-based compound expressed by formula I (A is coupler residue), e.g. a compound expressed by formula III and a diazonium salt expressed by formula II (X is anion). The compound expressed by formula I, e.g. a compound expressed by formula Ia is obtained by dropping sodium nitrite or nitrous acid into an acidic aqueous solution of an amine-based compound expressed by formula IV at a low temperature while stirring the acidic aqueous solution, then adding an acid to be an origin of the anion (X), providing a crystallized new tetrazonium salt expressed by formula IIa, subsequently adding a prescribed amount of a coupler expressed by the formula HA to the resultant tetrazonium salt and carrying out coupling reaction. Since the structure of o-terphenyl known as a quencher is introduced into the molecule of the azo-based compound expressed by formula I, its sensitivity is high and surface potential can be prevented from deteriorating by repeated use. Light stability is further excellent.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to various photosensitive materials such as charge generating materials for electrophotographic photoreceptors, azo compounds suitable as pigments and solar cells, and diazonium as an intermediate suitable for their production. It is about salt.

[0002]

2. Description of the Related Art Inorganic photoconductors such as selenium and cadmium sulfide have hitherto been used as charge generating materials used in various photosensitive materials such as charge generating materials in electrophotographic photoreceptors, pigments and solar cells. As is known, they are toxic and undesirably costly to produce.

Therefore, in place of these inorganic substances, various organic substances which are excellent in workability and advantageous in terms of manufacturing cost and have a high degree of freedom in functional design have been proposed as charge generating materials. .. As the organic charge generation material, many compounds such as phthalocyanine compounds, perylene compounds, quinacridone compounds, anthanthrone compounds and azo compounds have been proposed. For example, as azo compounds, there are JP-A-47-37543 and JP
The one disclosed in JP-A-7-195767 is known.

[0004]

However, the above-mentioned conventional charge generating materials have problems that the photosensitive wavelength region is narrow and the sensitivity is low. In addition, the above-mentioned conventional charge generating material has also insufficient light stability. The present invention solves the above problems and has high sensitivity,
It is also an object of the present invention to provide a novel azo compound having excellent light stability and a diazonium salt as an intermediate suitable for the production of this azo compound.

[0005]

Means and Actions for Solving the Problems In order to solve the above-mentioned problems, the present inventors have
The present invention has been completed in consideration of improving the sensitivity and photostability by introducing the structure of o-terphenyl known as a quencher. That is, the azo compound of the present invention has the general formula (I):

[0006]

[Chemical 3]

[Wherein A represents a coupler residue]. Further, the diazonium salt of the present invention as an intermediate suitable for the production of the azo compound represented by the general formula (I) has the general formula (II):

[0008]

[Chemical 4]

[Wherein X represents an anion]. As described above, the azo compound represented by the general formula (I) has a structure of o-terphenyl, which is known as a quencher, in the molecule as described above. Can be prevented. Furthermore, it is possible to stably maintain a high sensitivity to long-time exposure or exposure at high temperature, and it is excellent in light stability.

The reason why the azo compound of the present invention has such high sensitivity and photostability is considered as follows. That is, the azo compound of the present invention is represented by, for example, the following general formula (III) shown in the above-mentioned JP-A-47-37543:

[0011]

[Chemical 5]

A conventional bisazo type compound represented by the formula: wherein A represents the same coupler residue as above and Y represents a hydrogen atom, a methyl group, a methoxy group, an ethoxy group, a hydroxyl group, a chlorine atom or a bromine atom. Compared to a compound or the like, the π-electron conjugated system formed by the o-terphenyl moiety and two azo groups has a larger spread, and thus planarization of the molecular structure of the compound is further promoted, It is presumed that this is because intermolecular interaction due to overlap between molecules is strengthened.

The azo compound of the present invention represented by the above general formula (I) basically contains a bisazo compound represented by the following general formula (Ia).

[0014]

[Chemical 6]

[Wherein A represents the same coupler residue as described above] Further, an intermediate suitable for the production of the bisazo compound is a tetrazonium salt (bisdiazonium salt) represented by the following general formula (IIa): ) Is given.

[0016]

[Chemical 7]

[Wherein X represents the same anion as described above]
In the azo compound of the present invention represented by the general formulas (I) and (Ia), the coupler residue A is represented by the following general formulas (a) to
Examples are the groups represented by (g).

[0018]

[Chemical 8]

In each formula, R ⁴ is a hydroxyl group, a group represented by the following general formula: —NR ¹⁰ R ¹¹ (wherein R ¹⁰ and R ¹¹ are the same or different and represent a hydrogen atom or an alkyl group). Or a group represented by the following general formula: —NHSO ₂ R ¹² (in the formula, R ¹² represents a hydrogen atom, an alkyl group, an alkenyl group or an aryl group).

R ⁵ represents a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group, a carboxyl group, an alkoxycarbonyl group, a carbamoyl group, an aryl group or a sulfamoyl group, and the alkyl group or the alkoxy group represents a halogen atom, a phenyl group, It may have a substituent such as a naphthyl group, a nitro group and a cyano group. In addition, the carbamoyl group or the sulfamoyl group may have a substituent such as a halogen atom, a phenyl group, a naphthyl group, an alkyl group, an alkenyl group, a carbonyl group or a carboxyl group.

R ⁶ represents an atomic group necessary for forming an aromatic ring, an aliphatic ring or a hetero ring by being condensed with the benzene ring having R ⁴ and R ⁵ described above, and these rings are the same as those described above. May have a substituent. R ⁷ represents a hydrogen atom, an amino group, an N-substituted amino group, an alkyl group, an alkenyl group, a hydroxyl group, a carbamoyl group, a carboxyl group or an alkoxycarbonyl group, and the alkyl group, the alkenyl group and the carbamoyl group are the same as defined above. May have a substituent.

R ⁸ represents a hydrogen atom, an alkyl group or an aryl group, and the alkyl group or the aryl group may have a substituent similar to the above. R ⁹ represents a phenylene group or a naphthylene group. These phenylene groups or naphthylene groups may also have the same substituents as described above. Examples of the alkyl group include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, and a tert group.
A butyl group, a pentyl group, a hexyl group, etc., having 1 to 1 carbon atoms
And 6 lower alkyl groups.

As the aryl group, for example, a phenyl group,
Examples thereof include a tolyl group, a xylyl group, a biphenyl group, a naphthyl group, an anthryl group and a phenanthryl group. As the alkenyl group, for example, vinyl group, allyl group, 2-butenyl group, 3-butenyl group, 1-methylallyl group, 2-
Examples thereof include lower alkenyl groups having 2 to 6 carbon atoms such as pentenyl group and 2-hexenyl group.

Examples of the halogen atom include chlorine atom, bromine atom, iodine atom and fluorine atom. Examples of the alkoxy group include a lower alkoxy group having 1 to 6 carbon atoms in the alkoxy moiety, such as a methoxy group, an ethoxy group, a propoxy group, an isopropoxy group, a butoxy group, an isobutoxy group, a pentyloxy group and a hexyloxy group. Be done.

The alkoxycarbonyl group is, for example, an alkoxy moiety such as a methoxycarbonyl group, an ethoxycarbonyl group, a propoxycarbonyl group, an isopropoxycarbonyl group, a butoxycarbonyl group, an isobutoxycarbonyl group, a pentyloxycarbonyl group and a hexyloxycarbonyl group. And a lower alkoxycarbonyl group having 1 to 6 carbon atoms.

Examples of the acyl group include formyl group, acetyl group, propionyl group, butyryl group, isobutyryl group, valeryl group, isovaleryl group and hexamoyl group. In R ⁶ , the atomic group necessary for condensing with the benzene ring having R ⁴ and R ⁵ to form an aliphatic ring includes, for example, methylene group, ethylene group, propylene group, butylene group, and the like. 1-4 alkylene groups can be mentioned.

Further, in R ⁶ , the atomic group necessary for forming a heterocycle by being condensed with the benzene ring having R ⁴ and R ⁵ is, for example, a benzofuranyl group, a benzothiophenyl group, an indolyl group, 1H- Indolyl group, bezoxazolyl group, benzothiazolyl group, 1H-indazolyl group, benzimidazolyl group, chromenyl group, chromanyl group, isochromanyl group, quinolinyl group, isoquinolinyl group, cinnolinyl group, phthalazinyl group, quinazonilyl group, quinoxalinyl group, dibenzofuranyl group, carbazolyl group Group, xanthenyl group, acridinyl group, phenanthridinyl group, phenazinyl group, phenoxazinyl group,
Examples thereof include thianthrenyl group.

The aromatic heterocyclic group formed by condensing the benzene ring having R ⁴ and R ⁵ with R ⁶ is, for example, a thienyl group, a furyl group, a pyrrolyl group, an oxazolyl group, an isoxazolyl group or a thiazolyl group. , Isothiazolyl group, imidazolyl group, pyrazolyl group, triazolyl group, tetrazolyl group, pyridyl group and thiazolyl group. Further, it may be a heterocyclic group condensed with an aromatic ring (for example, a benzofuranyl group, a benzimidazolyl group, a benzoxazolyl group, a benzothiazolyl group, a quinolyl group).

Specific examples of the coupler residue A represented by the above general formulas (a) to (g) include the following groups.

[0030]

[Chemical 9]

In the diazonium salt of the present invention represented by the general formula (II) (IIa), the anion X is
Examples thereof include anions of hydrohalic acids such as hydrochloric acid, borofluoric acid, hydrobromic acid, sulfuric acid, nitric acid, perchloric acid and other acids. The azo compound of the present invention represented by the general formula (I) can be synthesized by various methods via the diazonium salt of the present invention represented by the general formula (II) as an intermediate. For example, taking the bisazo compound represented by the general formula (Ia) as an example, as shown in the following reaction formula, the general formula
By diazotizing each of the two amino groups in the amine compound represented by (1) to form a tetrazonium salt (IIa), and then coupling this with a predetermined coupler in an organic solvent, it is easy to It can be manufactured.

[0032]

[Chemical 10]

[In the formula, A and X are the same as above] In the diazotization, while stirring an acidic aqueous solution of the amine compound (1),
Sodium nitrite or nitrite at low temperature (usually -10
(About 5 ° C.), and then the acid as the source of the anion X is added to obtain a crystallized tetrazonium salt (IIa). Next, a bisazo compound (Ia) is obtained by adding a predetermined amount of coupler (2) to the tetrazonium salt (IIa) in an organic solvent to cause a coupling reaction.

As the organic solvent used in the above reaction,
Examples thereof include dimethylformamide and dimethyl sulfoxide. The azo compound of the present invention can be used in various fields such as various light-sensitive materials and pigments, solar cells, etc., in addition to the charge generating material in the electrophotographic photoreceptor described above.

[0035]

The present invention will be described in detail below with reference to examples. * Synthesis Example A of diazonium salt A 100 ml of saturated aqueous ammonia, 0.378 g of 2,2'-dibromo-o-terphenyl represented by the following formula (3)
(1 mmol) was added, and sodium amide (NaNH ₂ ) 0.192 g (2
Was added dropwise, and after the addition was completed, stirring was continued for 24 hours.

[0036]

[Chemical 11]

After 24 hours, 6 g of acetic acid was added to the reaction solution, and then the reaction solution was poured into 1 liter of water to stop the reaction. Then, an organic matter was extracted from the water with chloroform and recrystallized with benzene and cyclohexane to obtain 185 mg of crystals of 2,2'-diamino-o-terphenyl represented by the formula (1) (yield 71%). ) Got.

5.98 g (0.023 mol) of the above 2,2'-diamino-o-terphenyl was added to 115 m of 10% hydrochloric acid.
In addition to l, stir while cooling in an ice-water bath, and keep the liquid temperature at -1 ° C.
Kept on. Next, 4.58 sodium nitrite was added to this solution.
An aqueous solution prepared by dissolving g (0.066 mol) in 13 ml of water was added dropwise over 30 minutes while maintaining the liquid temperature at -2 to 1 ° C, and after the addition was completed, the mixture was stirred for 1 hour and left to cool.
Then add 26 ml of 42% borofluoric acid to it,
The crystals formed are filtered, washed with ethanol and dried,
Thus, 8.10 g (yield: 69.1%) of tetrazonium difluoroborate in which X in the general formula (IIa) was —BF ₄ was obtained.

The analysis results of the obtained tetrazonium difluoroborate are shown below. Elemental analysis result Calculated as C ₁₈ H ₁₂ N ₄ B ₂ F ₈ (%): C: 47.22 H: 2.64 N: 12.24 Measured value (%): C: 47.20 H: 2.70 N: 12.22 Mass spectrometry result m / e = 457 (calculated value 457.9) * Synthesis of azo compound Example 1 Represented by the formula (A1) and 0.91 g (0.002 mol) of tetrazonium difluoroborate obtained in Example A above. 1.59 g (0.0) of couplers with coupler residues
06 mol) and N, N-dimethylformamide 150 m
It is dissolved in 1, and 0.54 g (0.00
(66 mol) dissolved in 7.5 ml of water at 17 to 22 ° C.
It was added dropwise over 5 minutes while maintaining After further stirring for 3 hours, the formed precipitate was filtered and washed with 200 ml of N, N-dimethylformamide 5 times. Next, it was washed twice with water and dried under reduced pressure to obtain 1.34 g (yield 81.0%) of a bisazo compound represented by the following formula (IV).

[0040]

[Chemical formula 12]

The analysis results of the obtained bisazo compound are shown below. Elemental analysis results Calculated as C ₅₄ H ₃₆ N ₆ O ₄ (%): C: 77.9 H: 4.36 N: 10.09 Measured value (%): C: 77.7 H: 4.20 N: 10.00 Mass spectrometry result m / e = 832 (Calculated value 832.9) IR 1675 cm ^-1 (Coupler C = O) Example 2 0.91 g (0.002 mol) of tetrazonium difluoroborate obtained in Example A above and the above formula (A2) 0.50 g (0.
Was used in the same manner as in Example 1 to synthesize 0.884 g (yield 88.8%) of a bisazo compound.

The analysis results of the obtained bisazo compound are shown below. Elemental analysis result Calculated value as C ₃₂ H ₂₆ N ₄ O ₂ (%): C: 77.08 H: 5.26 N: 11.24 Measured value (%): C: 76.86 H: 5.14 N: 11.20 Mass spectrometry result m / e = 498 (Calculated value 498.6) IR 3580 cm ^-1 (Coupler OH) Example 3 Represented by 0.91 g (0.002 mol) of tetrazonium difluoroborate obtained in the above Example A and the above formula (A3). 0.56 g (0.
Was used to synthesize 0.93 g of bisazo compound (yield 83.0%) in the same manner as in Example 1.

The analysis results of the obtained bisazo compound are shown below. Elemental analysis result Calculated value as C ₃₄ H ₃₈ N ₆ O ₂ (%): C: 72.57 H: 6.80 N: 14.93 Measured value (%): C: 72.49 H: 6.66 N: 14.89 Mass spectrometry result m / e = 562 (Calculated value 562.7) IR 3500 cm ^-1 (Coupler OH) Example 4 0.91 g (0.002 mol) of tetrazonium difluoroborate obtained in the above Example A and the above formula (A4) 0.43 g (0.
Was used to synthesize 0.79 g (yield 79.6%) of a bisazo compound in the same manner as in Example 1.

The analysis results of the obtained bisazo compound are shown below. Elemental analysis result Calculated value as C ₃₂ H ₂₈ N ₆ (%): C: 77.39 H: 5.68 N: 16.92 Measured value (%): C: 77.32 H: 5.62 N: 16.88 Mass spectrometry result m / e = 496 (calculated Value 496.6) IR 3580 cm ^-1 (Coupler NH) Example 5 0.91 g (0.002 mol) of tetrazonium difluoroborate obtained in Example A above and a coupler represented by the above formula (A5). 0.28 g (0.
Was used in the same manner as in Example 1 to synthesize 0.73 g of bisazo compound (yield 81.2%).

The analysis results of the obtained bisazo compound are shown below. Elemental analysis result Calculated value as C ₂₆ H ₂₂ N ₆ O ₂ (%): C: 69.32 H: 4.92 N: 18.65 Measured value (%): C: 69.22 H: 4.88 N: 18.63 Mass spectrometry result m / e = 450 (Calculated value 450.5) IR 1470 cm ^-1 (Coupler NH) Example 6 0.91 g (0.002 mol) of tetrazonium difluoroborate obtained in Example A above and the formula (A6) 0.91 g (0.
Was used to synthesize 1.23 g of bisazo compound (yield 83.2%) in the same manner as in Example 1.

The analysis results of the obtained bisazo compound are shown below. Calculated elemental analysis _{C 44 H 28 N 6 O 6} (%): C: 71.73 H: 3.83 N: 11.41 Found (%): C: 71.68 H : 3.77 N: 11.46 Mass analysis m / e = 736 (Calculated value 736.8) IR 1710 cm ^-1 (Coupler C = O) Example 7 With 0.91 g (0.002 mol) of tetrazonium difluoroborate obtained in the above Example A, the above formula (A7) was used. 10.8 g of a coupler having the coupler residue represented (0.
Was used in the same manner as in Example 1 to synthesize 1.30 g of bisazo compound (yield 78.9%).

The analysis results of the obtained bisazo compound are shown below. Elemental analysis result Calculated as C ₅₄ H ₃₀ N ₆ O ₄ (%): C: 78.44 H: 3.66 N: 10.16 Measured value (%): C: 78.52 H: 3.62 N: 10.20 Mass spectrometry result m / e = 826 (Calculated value 826.9) IR 1700 cm ^-1 (Coupler C = O) Comparative Examples 1 to 3 Bisazo compounds represented by the following formulas (i) to (iii) were designated as Comparative Examples 1 to 3, respectively.

Comparative Example 1:

[0049]

[Chemical 13]

Comparative Example 2:

[0051]

[Chemical 14]

Comparative Example 3:

[0053]

[Chemical 15]

The following tests were carried out on the bisazo compounds of the above Examples and Comparative Examples to evaluate their properties. Measurement of Charge Generation Efficiency The bisazo compound of each Example and Comparative Example and the polyester resin as the binder resin were mixed in an appropriate solvent so that the amount ratio of the bisazo compound was 10% by weight, A coating liquid was prepared by uniformly dispersing. Then, as shown in FIG. 1, this coating solution is applied to the ITO electrode layer 102 of the transparent sheet 101 having the ITO electrode layer 102 formed on one surface thereof.
Apply to the surface of the side where the
The resin dispersion layer 103 was formed. Then, a gold electrode layer 104 was laminated on the back surface of the pigment / resin dispersion layer 103 to prepare a sample.

Next, the ITO electrode layer 10 of the above sample was prepared.
2 and the gold electrode layer 104 were connected to the measurement circuit as shown in the figure. As shown in FIG. 2, the measurement circuit considers the sample equivalently as one capacitor, and forms a bridge circuit with this sample CS, one variable capacitor C1, and two fixed capacitors C2 and C3. Is.

Next, the power supply device 1 is connected to the bridge circuit.
While applying a voltage from 06, the sample pigment / resin dispersion layer 103 is irradiated with laser pulse light as excitation light from the transparent sheet 101 side to obtain the sample CS from the equilibrium state (light non-irradiation state). The amount of voltage displacement (voltage drop ΔV, unit mV) was measured by the storage scope 107 connected to the bridge circuit. As the light source for irradiating the sample CS with the laser pulse light, the nitrogen gas laser NL connected to the power supply device 106 via the switch SW and the laser light from the nitrogen gas laser NL are irradiated. , Sample CS
A dye laser DL for irradiating the laser pulse light to the laser beam, and a monitor device 108 for monitoring the light energy of the laser pulse light emitted from the dye laser DL via a half mirror HM provided in the optical path of the laser pulse light. Was used.

Then, the charge generation efficiency (η) was obtained from the measured displacement amount (ΔV) of the voltage of the sample CS by the following formula. Charge generation efficiency η = (C · ΔV / eNφ) · [1 / fv · f (ε1, ε2)] However, each symbol in the above formula is as follows. C: capacitance of sample (= 4.8 × 10 ⁻¹⁰ , dielectric constant of sample = 2.71) e: elementary charge Nφ: number of absorbed photons (= 5 × 10 ⁻¹⁰ , monitor device) Calculated from the light energy of the laser pulse light monitored by 108) fv: Volume fraction of pigment (= 7.25, volume fraction when the amount ratio of bisazo compound is 10% by weight) ε1: Dielectric of bisazo compound Ratios (all have been set to 4.45 because there are few structural differences) ε2: Dielectric constant of polyester resin (= 2.60) f (ε1, ε2): Correction function, calculated by the following formula.

F (ε1, ε2) = ε2 / [ε1 + 2ε2-fv · (ε1-ε2)] The electric field strength between both electrodes was 3 × 10 ⁷ V / m. Table 1 shows the amount of voltage displacement (ΔV) and the charge generation efficiency (η) calculated by the above formula in the samples using the bisazo compounds of the respective Examples and Comparative Examples. Light Stability Test Using the bisazo compounds of the above Examples and Comparative Examples as charge generating materials, single-layer type and laminated type photoconductors were prepared by the following procedure.

(Production of Single Layer Type Photoreceptor) 8 weight of bisazo compound as charge generating material and 3,3'-dimethyl-N, N, N ', N'-tetrakis-4- as charge transporting material. Methylphenyl- (1,1'-biphenyl)-
100 parts by weight of 4,4′-diamine and 100 parts by weight of a polyester resin as a binder resin are mixed and dispersed with a predetermined amount of tetrahydrofuran by using a ball mill,
A single layer type photosensitive layer coating solution was prepared.

This coating solution was prepared by applying a diameter of 80 mm and a length of 350 mm.
After being applied to the surface of the aluminum base tube by a dipping method, it is heated and dried at 100 ° C. for 30 minutes in a dark place to prepare a drum type electrophotographic photosensitive member having a single-layer type photosensitive layer having a film thickness of 24 μm. did. (Production of Laminated Photoreceptor) 100 parts by weight of polyvinyl butyral as a binder resin, 100 parts by weight of a bisazo compound as a charge generating material, and a predetermined amount of tetrahydrofuran were charged in a ball mill and mixed with stirring for 24 hours, A charge generation layer coating solution was prepared.

This coating solution was prepared by applying a diameter of 80 mm and a length of 350 mm.
After being applied on the surface of the aluminum base tube by the dipping method, it was dried in a dark place with hot air at 110 ° C. for 30 minutes to be cured to form a charge generation layer having a thickness of 0.5 μm. Next, 100 parts by weight of polycarbonate as a binder resin and 3,3'-dimethyl-N as a charge transport material,
N, N ', N'-tetrakis-4-methylphenyl-
(1,1'-biphenyl) -4,4'-diamine 100
By weight and a predetermined amount of toluene were stirred and mixed with a homomixer to prepare a charge transport layer coating liquid.

This coating solution was applied onto the charge generation layer previously formed on the surface of the raw tube by the dipping method, and the coating was performed at 90 ° C. for 30 minutes.
A drum type electrophotographic photoreceptor having a laminated photosensitive layer was formed by forming a charge transport layer having a film thickness of about 20 μm by drying with hot air for a minute. (Measurement of Light Stability) First, the single-layer type and laminated type photoconductors manufactured as described above were first subjected to an electrostatic copying tester (Gentec Cynthia 30M, trade name, manufactured by Gentech).
After charging the surface of the electrophotographic photosensitive member positively or negatively, the charged electrophotographic photosensitive member is exposed to an exposure intensity of 1 using a halogen lamp which is an exposure light source of an electrostatic copying test apparatus.
The surface potential was measured after 0.15 seconds had elapsed after the exposure was started under the condition of 0 lux and the residual potential V1r.p.
(V).

Next, the above photoreceptor was loaded in an electrostatic copying machine (Model No. DC-111 manufactured by Mita Kogyo Co., Ltd.) to continuously copy 1000 sheets, and after repeated exposure in the same manner as above. The residual potential V2r.p. Then, the difference ΔVr.p. (V) between the residual potentials V1r.p. and V2r.p. The results are shown in Table 1.

[0064]

[Table 1]

From the results of Table 1 above, the bisazo compounds of Examples 1 to 7, which are the azo compounds of the present invention, have higher charge generation efficiency and higher sensitivity than Comparative Examples 1 to 3. I knew it was. Further, the photoconductors using the bisazo compounds of Examples 1 to 7 have a smaller residual potential change amount due to repeated exposure than the photoconductors of Comparative Examples 1 to 3, and therefore, It was found that the bisazo compounds of Examples 1 to 7 were also excellent in light stability.

[0066]

INDUSTRIAL APPLICABILITY As described above, the azo compound of the present invention has high sensitivity and excellent light stability. It can be suitably used for solar cells and the like.
Further, the diazonium salt of the present invention is an intermediate suitable for the production of the azo compound.

[Brief description of drawings]

FIG. 1 is a block diagram showing an outline of an apparatus used for measuring charge generation efficiency in an example.

FIG. 2 is a circuit diagram showing more detailed contents of the device.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI Technical display location G03G 5/06 347 B 8305-2H (72) Inventor Yoichiro Watanabe 1-chome Tamatsukuri, Chuo-ku, Osaka City, Osaka No. 2 28 Mita Industry Co., Ltd.

Claims (2)

[Claims] 1. General formula (I): An azo compound represented by the formula: wherein A represents a coupler residue. 2. General formula (II): A diazonium salt represented by [wherein X represents an anion].