JP2960135B2 - Azo compound and photoreceptor for electrophotography using the same - Google Patents

Description

The present invention relates to an azo compound useful as a charge generating substance in an electrophotographic photoreceptor required for copying information and recording information, and an electrophotography using the same. To a photoreceptor for use.

[Conventional technology]

The technology of using an azo compound in the charge generation layer of an electrophotographic photoreceptor is disclosed in JP-A-54-22834, JP-A-60-153050,
It is known in JP-A-60-163048 and JP-A-63-264762. However, the sensitivity was inferior to that of the photoreceptor using any of the azo compounds and the selenium-based photoreceptor.

[Problems to be solved by the invention]

An object of the present invention is to provide a highly sensitive electrophotographic photoconductor.

[Means for solving the problem]

The present inventors have conducted intensive studies in order to solve the above-mentioned problems, and as a result, have found that the following general formula (I) [In the formula (I), Ar ¹ represents the following formula (A-1) or (A-
Represents an aromatic linking group represented by 2), Y represents a hydrogen atom, an amino group, a substituted or unsubstituted alkylamino group, a substituted or unsubstituted arylamino group, a substituted or unsubstituted alkylaminocarbonylamino group, a substituted or unsubstituted arylaminocarbonylamino group, X
Represents an organic residue condensing with a benzene ring to form an aromatic hydrocarbon ring or an aromatic heterocyclic ring, R ¹ represents a hydrogen atom, a halogen atom, a hydroxyl group or -ONa, and n represents 2 or 4 It has been found that a photoreceptor using the azo compound represented by the formula (1) as a charge-generating substance exhibits good sensitivity, and the present invention has been completed.

Specific examples of X in the general formula (I) include a hydrocarbon ring such as a naphthalene ring and an anthracene ring fused to a benzene ring to which an azo group is bonded, an indole ring, a carbazole ring, a benzocarbazole ring, and a dibenzofuran ring. Those which form a heterocyclic ring can be exemplified, and a naphthalene ring is particularly preferred as the formed ring. X may have a substituent, and examples of the substituent include a halogen atom such as a chlorine atom and a bromine atom, and a hydrogen group. The azo compounds that can be preferably used in the present invention are specifically shown in Tables 1 to 3.

The azo compound of the present invention can be produced by a known method as follows.

The amine compound represented by the general formula (IV) Ar ¹ NH ₂ ) _n (III) wherein, in the formula (III), Ar ¹ and n have the same meaning as in the general formula (I) is diazotized, and then diazotized. The compound obtained is isolated as it is or as a borofluoride, and then represented by the general formula (IV) [In the formula (IV), R ¹ , X and Y have the same meanings as in the general formula (I)].

The electrophotographic photoreceptor of the present invention comprises at least one of the azo compounds represented by the general formula (I) as a charge generating substance in a photosensitive layer on a conductive support. A typical structure of such a photoreceptor is shown in FIG. 1 and FIG. FIG. 1 shows a photoreceptor in which a dispersion type photosensitive layer 4 in which a charge generating substance 2 and a charge transporting substance 3 are dispersed in a binder is provided on a conductive support 1, and is shown in FIG. What is different is that a photosensitive layer 4 'of a lamination type comprising a charge generating layer 6 in which a charge generating substance is dispersed in a binder and a charge transporting layer 5 in which a charge transporting substance is dispersed in a binder is provided on the conductive support 1. It is a photoconductor.

Other examples include those in which the charge generation layer and the charge transport layer are reversed, and those in which an intermediate layer is provided between the photosensitive layer and the conductive support.

In the photoreceptor of FIG. 2, the image-exposed light transmits through the charge transport layer, and the charge generating substance generates charges in the charge generating layer. The generated charges are injected into the charge transport layer, and the charge transport material transports the charge.

The electrophotographic photoreceptor of the present invention comprises, in addition to the azo compound of the general formula (I), a conductive support, a binder, a charge transport material, and the like. There is no particular limitation as long as it has a function as a component.

That is, as the conductive support used in the photoreceptor of the present invention, aluminum, copper, a metal plate such as zinc,
A material obtained by vapor-depositing a conductive material such as aluminum or SnO _{2 on} a plastic sheet or a plastic film of polyester or the like, or paper, resin or the like subjected to conductive treatment is used.

As the binder, a vinyl polymer such as polystyrene, polyacrylamide, or poly-N-vinylcarbazole, or a condensation resin such as a polyamide resin, a polyester resin, an epoxy resin, a phenoxy resin, or a polycarbonate resin is used. Any resin having adhesiveness to the body can be used.

Charge transport materials are generally classified into two types, a hole transport material and an electron transport material, and both can be used in the photoreceptor of the present invention. Examples of the hole transport material include an electron-accepting material such as trinitrofluorenone or tetranitrofluorenone that easily transports electrons, and poly-N-.
Polymer containing heterocyclic compound represented by vinylcarbazole, triazole derivative, oxadiazole derivative, imidazole derivative, pyrazoline derivative, polyarylalkane derivative, phenylenediamine derivative, hydrazone derivative, amino-substituted chalcone derivative, triaryl An electron-donating substance that easily transports holes, such as an amine derivative, a carbazole derivative, and a stilbene derivative, may be used.

For example, 9-ethylcarbazole-3-aldehyde-1-methyl-1-phenylhydrazone, 9-ethylcarbazole-3-aldehyde-1-benzyl-1-phenylhydrazone, 9-ethylcarbazole-3-aldehyde-1,1 -Diphenylhydrazone, 4 '-(4 "-diphenylamino-α-phenylstyryl) aldehyde-
1,1-diphenylhydrazone, 4-diethylaminostyrene-β-aldehyde-1-methyl-1-phenylhydrazone, 4-methoxynaphthalene-1-aldehyde-1
-Benzyl-1-phenylhydrazone, 4-methoxybenzaldehyde-1-methyl-1-phenylhydrazone, 2,4-dimethoxybenzaldehyde-1-benzyl-1-phenylhydrazone, 4-diethylaminobenzaldehyde-1,1-diphenylhydrazone, 4-methoxybenzaldehyde-1-benzyl-1- (4-methoxy) phenylhydrazone, 4-diphenylaminobenzaldehyde-1-benzyl-1-phenylhydrazone,
4-dibenzylaminobenzaldehyde-1,1-diphenylhydrazone, 1,1-bis (4-dibenzylaminophenyl) propane, tris (4-diethylaminophenyl) methane, 1,1-bis (4-dibenzylaminophenyl) ) Propane, 2,2'-dimethyl-4,4'-bis (diethylamino) -triphenylmethane, 9- (4-diethylaminostyryl) anthracene, 9-bromo-10- (4
-Diethylaminostyryl) anthracene, 9- (4-
Dimethylaminobenzylidene) fluorene, 3- (9
-Fluorenylidene) -9-ethylcarbazole, 1,2
-Bis (4-diethylaminostyryl) benzene, 1,2
-Bis (2,4-dimethoxystyryl) benzene, 3-styryl-9-ethylcarbazole, 3- (4-methoxystyryl) -9-ethylcarbazole, 4-diphenylaminostilbene, 4-dibenzylaminostilbene,
4-ditolylaminostilbene, 1- (4-diphenylaminostyryl) naphthalene, 1- (4-diethylaminostyryl) naphthalene, 4'-diphenylamino-α
-Phenylstilbene, 4'-methylphenylamino-
α-phenylstilbene, 1-phenyl-3- (4-diethylaminostyryl) -5- (4-diethylaminophenyl) pyrazoline, 1-phenyl-3- (4-dimethylaminostyryl) -5- (4-dimethylaminophenyl ) Pyrazoline and the like.

Other hole transporting substances include, for example, 2,5-bis (4-diethylaminophenyl) -1,3,4-oxadiazole, 2,5-bis [4- (4-diethylaminostyryl) phenyl] -1,3,4-oxadiazole, 2-
(9-ethylcarbazol-3-yl) -5- (4-diethylaminophenyl) -1,3,4-oxadiazole,
2-vinyl-4- (2-chlorophenyl) -5- (4-
Diethylaminophenyl) oxazole, 2- (4-diethylaminophenyl) -4-phenyloxazole,
9- [3- (4-diethylaminophenyl) -2-propenylidene] -9H-xanthene, poly-N-vinylcarbazole, halogenated poly-N-vinylcarbazole,
Polyvinyl pyrene, polyvinyl anthracene, pyrene formaldehyde resin, ethyl carbazole formaldehyde resin and the like can be mentioned.

Examples of the electron transporting substance include chloranil, bromanil, tetracyanoethylene, tetracyanoquinodimethane, 2,4,7-trinitro-9-fluorenone,
4,5,7-tetranitro-9-fluorene, 2,4,5,7-tetranitroxanthone, 2,4,8-trinitrothioxanthone, 2,6,8-trinitro-4H-indeno [1,2- b] Thiophene-4-one, 1,3,7-trinitrodibenzothiophene-5,5-dioxide and the like.

These charge transport materials may be used alone or in combination of two or more.

As the charge transporting material used in the present invention, the compound represented by the general formula (II) [In the formula (II), Ar ² , Ar ³ , and Ar ⁴ each independently represent a substituted or unsubstituted aromatic hydrocarbon, aromatic heterocycle, aralkyl group,
Represents an alkyl group, B represents a hydrogen atom, an alkyl group, an alkoxy group, or an alkyl group, an alkoxy group, or (Wherein Ar ⁵ and Ar ⁶ represent a substituted or unsubstituted aromatic hydrocarbon or aromatic heterocycle), and R ² represents an alkyl group or an alkoxy group.)
Are preferred.

An intermediate layer can be provided between the photosensitive layer and the conductive support, if necessary. As the material, polyamide, nitrocellulose, casein, polyvinyl alcohol, and the like are suitable, and the film thickness is preferably 1 μm or less.

A conventionally known method can be used for manufacturing the photoconductor. For example, in the case of a laminated photoreceptor, fine particles of an azo compound are dispersed in a solution in which a binder is dissolved, coated on a conductive support, and dried to obtain a charge generation layer.
A charge transport layer can be prepared by applying and drying a solution in which a charge transport material and a binder are dissolved. Other methods can be used to form the charge generation layer. For example, there is a method of vacuum-depositing an azo compound, or a method of applying and drying a solution of an azo compound. The former is expensive, and the latter uses an organic amine that is generally inconvenient to handle, such as ethylenediamine, n-butylamine, and the like. A coating method of a fine particle dispersion of an azo compound is preferable because of a manufacturing defect. The coating method is performed by usual means, for example, doctor blade, dipping, wire bar and the like. The optimum range of the thickness of the photosensitive layer differs depending on the type of the photoconductor. For example, in the case of the photoreceptor as shown in FIG. 1, the thickness is preferably 3 to 50 μm, more preferably 5 to 30 μm.

In the photoreceptor as shown in FIG. 2, the thickness of the charge generation layer 6 is preferably 0.01 to 5 μm, more preferably 0.05 to 2 μm. When the thickness is less than 0.01 μm, the generation of electric charges is not sufficient, and when the thickness exceeds 5 μm, the residual potential becomes high, which is not practically preferable. The thickness of the charge transport layer 5 is preferably 3 to 50 μm, more preferably 5 μm.
When the thickness is less than 3 μm, the charge amount is insufficient, and when the thickness exceeds 50 μm, the residual potential is high and is not practically preferable.

Although the content of the azo compound represented by the general formula (I) in the photosensitive layer varies depending on the type of the photosensitive member, in the photosensitive member as shown in FIG. ,
More preferably, it is at most 20% by weight. Further, this layer contains a charge transporting substance preferably in an amount of 10 to 95% by weight, more preferably 30 to 90% by weight.

In the photoreceptor as shown in FIG. 2, the proportion of the azo compound in the charge generation layer 6 is preferably at least 30% by weight, more preferably at least 50% by weight. In addition, during charge transport 5
Contains 10 to 95% by weight, preferably 30 to 90% by weight of a charge transport material. If the amount of the charge transporting substance is less than 10% by weight in this layer, almost no charge is transported, and
If the content is more than 10% by weight, the photoreceptor has poor mechanical strength and is not practically preferable.

〔The invention's effect〕

In the present invention, by using an azo compound in which the coupler component of the azo compound is a sodium salt as the charge generating substance, it is possible to provide an electrophotographic photoreceptor having high sensitivity and low residual potential.

〔Example〕

Hereinafter, the present invention will be described specifically with reference to Examples, but the embodiments of the present invention are not limited thereto.

Example 1 The following formula (A) The azo compound 200 of Exemplified Compound No. 2 shown in Table 1
Parts, polyester resin (trade name “Byron 200” manufactured by Toyobo) 200 parts, cyclohexanone 6000 parts and glass beads 100
Part 0 was shaken with a shaker. Thereafter, the glass beads were removed to obtain a coating liquid.

This coating solution was applied to an aluminum plate and dried to form a charge generation layer. The thickness was 0.7 μm.

Next, the following formula (B) Was dissolved in chloroform, and the solution was coated and dried on the charge generation layer to form a charge transport layer. Its film thickness was 20 μm.

Thus, an electrophotographic photoreceptor as shown in FIG. 2 was produced.

The electrophotographic photoreceptor was charged by corona discharge at an applied voltage of −6 KV using an electrostatic copying paper tester (Model EPA-8100 manufactured by Kawaguchi Electric Works), and the surface potential V ₀ at that time was measured. and left at the next two seconds dark was measured the surface potential V ₂ at that time. Then, a halogen lamp (color temperature 2856 ゜ K) with the surface illuminance of the photoconductor at 51ux
The half-exposure amount E 1/2 (1 ux · see) was calculated by measuring the time when the surface potential becomes 1/2 of V ₂ by irradiating light. The surface potential V ₁₂ after 10 seconds of light irradiation, that is, the residual potential was measured. As a result, the sensitivity was E 1/2 = 1.1 lux · sec V ₁₂ = 5 V.

Production Example 1 [Production of compound of formula (A)] 1.4 g of 2,7-diaminofluorenone was suspended in 3.5 ml of 35% hydrochloric acid and 45 ml of water, kept at 60 ° C. for 30 minutes, and then heated at 0 ° C. with sodium nitrite 1.4 g. g in 6 ml of water was added dropwise. 0
After stirring at 1 ° C. for 1 hour, insolubles were removed and 15 ml of 42% borofluoric acid was added. The precipitated crystals are filtered and dried,
2.4 g of diazonium borofluoride was obtained.

2.0 g of 2-sodiumoxy-3-formylnaphthalene was dissolved in 200 ml of N, N-dimethylformamide and cooled to 0 to 5 ° C. 2.0 g of the diazonium borofluoride was added,
Stir for 5 minutes. A solution of 1.6 g of sodium acetate dissolved in 30 ml of water was added dropwise at 0 to 5 ° C. After stirring at the same temperature for 30 minutes, the mixture was stirred at room temperature for 4 hours. The resulting precipitate was filtered and washed with N, N-dimethylformamide, acetone, methanol, and water in this order. After drying, 1.7 g of a black powder was obtained. Melting point
It was 270 ° C or higher.

The obtained compound was confirmed to be a compound of Formula (A) (Exemplary Compound No. 2) by elemental analysis.

Elemental analysis value CHN Calculated value (%) 67.75 2.92 9.03 Actual value (%) 67.61 2.87 8.97 The amount of sodium was analyzed by atomic absorption spectrometry.
20%. (Calculated value 7.41%) In addition, 2-sodiumoxy-3-formylnaphthalene was synthesized as follows. 2-Hydroxy-3-formylnaphthalene was dissolved in 150 ml of benzene, 3 g of sodium methoxide was added, and the precipitated crystals were separated by filtration and dried to obtain the desired product.

Comparative Example 1 0.5 part of a polyester resin (trade name “Vylon 200” manufactured by Toyobo), 0.5 part of the compound of the formula (C) and 50 parts of cyclohexanone were pulverized and mixed by a ball mill, and the obtained dispersion was placed on an aluminum plate by a wire bar. Coating using, 20 at 80 ℃
After drying for a minute, a 0.7 μm charge generation layer was formed. A charge transport layer was formed on this charge generation layer in the same manner as in Example 1.

The sensitivity of this electrophotographic photoreceptor was E 1/2 = 3lux · sec V ₁₂ = 20V.

Compound of formula (C) Example 2 The following formula (D) Of 200 parts of an azo compound of Exemplified Compound No. 6, 200 parts of a polyester resin (trade name “Vylon 200” manufactured by Toyobo), and 20,000 parts of tetrahydrofuran are crushed and mixed by a ball mill, and the obtained dispersion liquid is wire-bonded to an aluminum plate. The coating was dried using a bar to form a charge generation layer of about 1 μm. A solution prepared by dissolving 1 part of the compound of the formula (B) and 1 part of a polycarbonate resin (trade name “Panlite K-1300” manufactured by Teijin Chemicals) in 10 parts of chloroform is applied to the charge generation layer using a wire bar. Dry at ℃ 30 minutes, about 18μ thick
m of the charge transport layer was formed to produce a laminated electrophotographic photoreceptor shown in FIG.

The sensitivity of this photoreceptor was E 1/2 = 0.6 lux · sec V ₁₂ = 1V.

Production Example 2 [Production of Compound of Formula (D)] 2-Hydroxy-3-naphthalenecarboxylic acid chloride
9.0 g, 5.2 g of 4-methyl-7-amino-coumarin, 50 ml of toluene and 40 ml of THF were mixed, and 3.63 g of dimethylaniline was added dropwise with stirring. After reacting at 80 ~ 90 ゜ for 3 hours,
Add 20 ml of dimethylimidazolidinone (DMI) and add 80-90
The reaction was performed for 8 hours. After cooling to room temperature, 30 ml of water were added. After filtration, washing with methanol and drying, 6.1 g of a compound of the following formula (E) was obtained.

6.1 g of the compound of formula (E) is treated with N, N'-dimethylformamide 5
The crystals were dissolved in 0 ml, 50 g of a 5% aqueous sodium hydroxide solution was added, and the precipitated crystals were separated by filtration and dried to obtain 5 g of a sodium salt represented by the following formula (F).

5.0 g of this coupler compound (F) was dissolved in 300 ml of N, N-dimethylformamide to give a coupler solution.

2,7-Diaminofluorenone (1.4 g) was suspended in 35% hydrochloric acid (3.5 ml) and water (45 ml), kept at 60 ° C. for 30 minutes, and added dropwise with a solution of 1.4 g of sodium nitrite in 6 ml of water at 0 ° C. 0
After stirring at 1 ° C. for 1 hour, insolubles were removed and 15 ml of 42% borofluoric acid was added. The precipitated crystals are filtered and dried,
2.4 g of diazonium borofluoride was obtained.

2.4 g of the obtained diazonium borofluoride was added to the above coupler liquid at 5 ° C. or lower, and the mixture was stirred for 10 minutes. Next, a solution in which 1.9 g of sodium acetate was dissolved in 20 ml of water was added at 10 ° C. or lower, and the mixture was stirred for 30 minutes, returned to room temperature, and stirred for 3 hours. The resulting precipitate was filtered and washed with N, N-dimethylformamide, acetone, methanol, and water in this order. Dry black powder
3.6 g (melting point 270 ° C. or higher) were obtained. The obtained compound was confirmed to be a compound of the formula (D) (exemplified compound No. 6) by elemental analysis.

Elemental analysis value Calculated value for CHN (%) 68.31 3.35 8.69 Actual value (%) 68.32 3.10 8.65 The sodium content was 4.90% as measured by atomic absorption spectrophotometry. (Calculated value: 4.76%) Example 3 0.5 part of butyral resin (trade name: Slek BM-2, manufactured by Sekisui Chemical Co., Ltd.), 0.5 part of Exemplified Compound (No. 9), and 25 parts of cyclohexanone were pulverized and mixed by a ball mill, and obtained. Apply the dispersion on an aluminum plate using a doctor,
After drying for a minute, a charge generation layer having a thickness of 0.5 μm was formed. A charge transport layer using the compound of the formula (B) was formed on the charge generation layer in the same manner as in Example 1 to produce a laminated electrophotographic photoconductor. The sensitivity of this photoreceptor was E 1/2 = 0.7 lux · sec V ₁₂ = 1V.

Production Example 3 [Production of Exemplified Compound No. 9] The following formula (H) 11 g of a compound represented by N, N'-dimethylformamide 10
0 ml, followed by addition of 50 g of 5% caustic soda water, and the precipitated crystals were separated by filtration, dried and 7.3 g of a coupler of the following formula (J).
I got

In a 100 ml beaker, the following formula (L) Of amine, 50 ml of water and 4 g of 35% hydrochloric acid were added and mixed for 1 hour. After adding 5 g of a 20% aqueous sodium nitrite solution and stirring at 0 ° C. for 1 hour, the insoluble matter was filtered off, 15 ml of 42% borofluoric acid was added to the filtrate, and the precipitated crystals were filtered and dried to obtain diazonium and borofluoride. I got

To 200 ml of N, N'-dimethylformamide was added 3.3 g of a coupler (J), followed by 2.0 g of the above diazonium borofluoride at 0 to 5 ° C., followed by stirring for 5 minutes. 32 g of a 5% sodium acetate aqueous solution is added at 0 to 5 ° C., and at the same temperature for 30 minutes,
Stirred at room temperature for 4 hours.

The precipitated crystals are separated by filtration, washed with N, N'-dimethylformamide, acetone, methanol and water in this order, and dried.
Exemplary compound No. 9 was obtained. The elemental analysis values of the obtained compound were as follows.

Elemental analysis value CHNS Cl Calculated value (%) 63.94 3.13 9.32 1.78 7.86 Observed value (%) 63.81 3.03 9.28 1.75 7.68 The sodium content was 5.02 by atomic absorption spectrophotometry.
%Met. (Calculated value: 5.10%) Comparative Example 3 In Example Compound No. 9, -ONa
In the same manner as in Example 3, except that an azo compound having -OH was used instead, a multilayer electrophotographic photosensitive member was produced.

The sensitivity of this photoreceptor was E 1/2 = 1.5 lux · sec V ₁₂ = 30 V.

BRIEF DESCRIPTION OF THE DRAWINGS FIGS. 1 and 2 are cross-sectional views showing a configuration example of an electrophotographic photosensitive member. In FIG. 1 and FIG. 2, reference numerals are as follows. DESCRIPTION OF SYMBOLS 1 ... Conductive support, 4,4 '... Photosensitive layer 2 ... Charge generation layer, 5 ... Charge transport layer 3 ... Charge transport layer, 6 ... Charge generation layer

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-2-210451 (JP, A) JP-A-54-59143 (JP, A) JP-A-2-179647 (JP, A) JP-A 49-59 81439 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) G03G 5/06 C09B 35/00 CA (STN) CAOLD (STN) REGISTRY (STN)

Claims (3)

(57) [Claims] 1. A compound represented by the following general formula (I) [In the formula (I), Ar ¹ represents the following formula (A-1) or (A-
Represents an aromatic linking group represented by 2), Y represents a hydrogen atom, an amino group, a substituted or unsubstituted alkylamino group, a substituted or unsubstituted arylamino group, a substituted or unsubstituted alkylaminocarbonylamino group, a substituted or unsubstituted arylaminocarbonylamino group, X
Represents an organic residue condensing with a benzene ring to form an aromatic hydrocarbon ring or an aromatic heterocyclic ring, R ¹ represents a hydrogen atom, a halogen atom, a hydroxyl group or -ONa, and n represents 2 or 4 ] A photoreceptor for electrophotography, comprising an azo compound represented by the formula (1) as a charge generating substance. 2. A laminated electrophotographic photoconductor according to claim 1, wherein the electrophotographic photoconductor comprises a charge transport layer and a charge generation layer. 3. The laminated electrophotographic photoreceptor according to claim 2, wherein the charge transport layer has the following general formula (II): [In the formula (II), Ar ² , Ar ³ , and Ar ⁴ each independently represent a substituted or unsubstituted aromatic hydrocarbon, aromatic heterocycle, aralkyl group,
Represents an alkyl group, B represents a hydrogen atom, an alkyl group, an alkoxy group, or (Wherein Ar ⁵ and Ar ⁶ represent a substituted or unsubstituted aromatic hydrocarbon or an aromatic heterocyclic ring), and R ² represents an alkyl group or an alkoxy group.) Photoconductor for electrophotography.