JP2883703B2 - Electrophotographic photoreceptor - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic photosensitive member necessary for copying information and recording information.

[Conventional technology]

Techniques of using an azo compound in the charge generation layer of an electrophotographic photoreceptor are known in JP-A-54-22834, JP-A-60-153050, JP-A-60-163048 and JP-A-63-264762.
However, the photoreceptors using any of the azo compounds were inferior in sensitivity as compared with the selenium-based photoreceptors.

[Problems to be solved by the invention]

An object of the present invention is to produce a highly sensitive electrophotographic photosensitive member.

[Means for solving the problem]

The present inventors have conducted intensive studies in order to solve the above-mentioned problems, and found that when sodium acetate was added to the charge generation layer in the laminated electrophotographic photoreceptor, the sensitivity was significantly improved, and the present invention was found. It has arrived.

That is, the present invention relates to a laminated electrophotographic photoreceptor comprising a charge generation layer and a charge transport layer, wherein the charge generation layer contains an azo compound and sodium acetate.

The electrophotographic photoreceptor of the present invention comprises an azo compound, particularly a compound represented by the following general formula (I): [Wherein, Ar ¹ represents a divalent to tetravalent aromatic linking group, and Y represents a hydrogen atom, a hydroxy group, an amino group, an aromatic amino group, a carbamoylamino group, an aromatic aminocarbonylamino group, or an aliphatic amino group. Wherein X represents an organic residue condensed with a benzene ring to form an aromatic hydrocarbon ring or an aromatic heterocyclic ring, R represents a hydrogen atom, a halogen atom, or a hydroxyl group, and n is an integer of 2 to 4. 10,000 parts by weight of an azo compound represented by
000 parts by weight and 5,000 to 20,000 parts by weight of a resin are mixed in an appropriate dispersion solvent, and a coating solution obtained by atomization and dispersion is applied to a conductive support to form a charge generation layer. It is manufactured by applying a coating solution in which a charge transport material and a resin are dissolved to form a charge transport layer.

FIG. 1 shows a typical configuration of such a photoreceptor.
That is, a photosensitive layer 4 of a laminated type comprising a charge generating layer 2 in which a charge generating substance is dispersed in a binder and a charge transporting layer 3 in which a charge transporting substance is dispersed in a binder.
Is a photoconductor for electrophotography provided with.

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. 1, the image-exposed light passes 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.

In the present invention, as the azo compound contained in the charge generation layer, a known azo compound can be used, and the azo compound of the general formula (I) is particularly preferable.

In the general formula (I), the divalent to tetravalent aromatic linking group represented by Ar ^{1 represents a} substituted or unsubstituted aromatic hydrocarbon ring or an aromatic heterocyclic ring which may be bonded through a bonding group. However, as the aromatic hydrocarbon ring, benzene, naphthalene, anthracene, pyrene, phenanthrene, fluorene, anthraquinone, fluorenone, benzuanthrone and the like, as the aromatic heterocyclic ring, thiophene, dibenzothiophene, pyridine, carbazole, benzoxazole, Benzothiazole and the like. When the compound has a substituent, examples of the substituent include an alkyl group such as a methyl group, an ethyl group, a propyl group and a butyl group, an alkoxy group such as a methoxy group, an aryl group such as a phenyl group and a naphthyl group, a diethylamino group, and a diphenyl group. Examples include a substituted amino group such as an amino group, a halogen atom such as a fluorine atom, a chlorine atom, and a bromine atom, a hydroxyl group, a nitro group, and a cyano group. Further, the aromatic hydrocarbon ring and the aromatic heterocyclic ring may be engaged via a bonding group, and the bonding group includes -O-, -S-, -CO-, and -CH = CO-. , And the like.

Ar ¹ which can be preferably used in the present invention is specifically exemplified below.

X in the general formula (I) is specifically condensed with a benzene ring to which an azo group is bonded to form a hydrocarbon ring such as a naphthalene ring or an anthracene ring, an indole ring, a carbazole ring, a benzocarbazole ring, a dibenzofuran ring, or the like. Can be exemplified, and a naphthalene ring is particularly preferable 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 hydroxyl group. The azo compounds that can be preferably used in the present invention are specifically shown in Tables 1 to 3.
In Table ¹ , (A-1) to (A-15) in Ar ¹ are the structural formulas described above.

In the present invention, particularly preferred azo compounds include compounds represented by the general formula (II) [In the formula (II), Y has the same meaning as in the general formula (I)].

The azo compound that can be used in the present invention can be synthesized by a known method as follows.

An amine represented by the general formula (IV) Ar ¹ NH ₂ ) _n (IV) wherein Ar ¹ and n have the same meaning as in the general formula (I) is diazotized, and then the diazotized compound is used as it is. Alternatively, after isolation as a borofluoride, the compound represented by the general formula (V) [Wherein, R, X and Y have the same meaning as in the general formula (I)], and can be easily produced by coupling with a coupler compound represented by the following formula:

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-diphenylaminostilbenzene, 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-diethylaminophenol) pyrazolin, 1-phenyl-3- (4-dimethylaminostyryl) -5- (4-dimethylaminophenyl) pyrazolin 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, a compound represented by general formula (III) [In the formula (III), Ar ² , Ar ³ , and Ar ^{4 each} represent an alkyl group, an aromatic hydrocarbon group, or an aromatic heterocyclic group, and m represents an integer of 1 to ^3.]

The electrophotographic photoreceptor of the present invention comprises an azo compound, particularly an azo compound of the general formula (I), sodium acetate and a charge transporting substance, a binder, a conductive support, and the like. There is no particular limitation as long as it has a function as a component of the photoconductor.

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.

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, an azo compound and sodium acetate fine particles 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 coating and drying. Other methods can be used to form the charge generation layer. For example, there is a method in which sodium acetate is added to a solution of an azo compound, followed by coating and drying. Is preferred. 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.

In the photoreceptor as shown in FIG. 1, the thickness of the charge generation layer 2 is preferably 0.01 to 5 μm, more preferably 0.05 to 5 μm.
2 μm. If the thickness is less than 0.01 μm, the generation of electric charge is not sufficient, and if it exceeds 5 μm, the residual potential is high, which is not practically preferable.

The thickness of the charge transport layer 3 is preferably 3 to 50 μm, and more preferably 5 to 30 μm. If the thickness is less than 3 μm, the charge amount is insufficient.

Although the content of the azo compound represented by the general formula (I) in the photosensitive layer varies depending on the type of the photoreceptor, in the photoreceptor as shown in FIG. 1, the ratio of the azo compound in the charge generation layer 2 is preferable. Is at least 30% by weight, more preferably at least 50% by weight. The amount of sodium acetate used is 5 to 1000 parts by weight based on 10,000 parts by weight of the azo compound. The charge transport layer 3 contains a charge transport material in an amount of 10 to 95% by weight, preferably 30 to 90% by weight. If the amount of the charge transporting substance in this layer is less than 10% by weight, the charge is hardly transported, and if it exceeds 95% by weight, the mechanical strength of the photoconductor is poor, which is not practically preferable.

〔The invention's effect〕

In the present invention, by adding sodium acetate to the charge generation layer containing the azo compound, 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. 3 in Table 1 shown by
Parts, polyester resin (trade name: Byron 200, manufactured by Toyobo), 200 parts, sodium acetate 0.5 part, cyclohexanone 6000 parts, and glass beads 1000 parts were shaken with a shaking machine. Thereafter, the glass beads were removed to obtain a coating liquid.

The coating solution was applied to an aluminum plate and dried. The thickness of the obtained charge generation layer was 0.7 μm.

Next, the following formula (B) Are dissolved in chloroform, and 100 parts of a polycarbonate resin (trade name “Panlite K-1300” manufactured by Teijin Chemicals Ltd.) is dissolved in chloroform, and laminated on the charge generation layer on the aluminum plate. The thickness of the charge transport layer was 20 μm.

Thus, an electrophotographic photosensitive member as shown in FIG. 1 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 1 ux · 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-hydroxy- in 200 ml of N, N-dimethylformamide
2.0 g of 3-formylnaphthalene was dissolved and cooled to 0 to 5 ° C. 2.0 g of the diazonium borofluoride was added and stirred 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,
Stirred for 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. 270 melting point
° C or higher.

The obtained compound was confirmed to be Exemplified Compound No. 3 from the elemental analysis value and the infrared absorption spectrum.

Elemental analysis value CHN Calculated value (%) 72.92 3.47 9.72 Observed value (%) 72.47 3.36 9.54 The infrared absorption spectrum (KBr method) of this compound was compared with that of the second.
Shown in the figure.

Comparative Example 1 0.5 parts of polyester resin (trade name “Vylon 200” manufactured by Toyobo), 0.5 parts of compound (A) and cyclohexanone
50 parts were pulverized and mixed by a ball mill, and the obtained dispersion was applied to an aluminum plate using a wire bar, and dried at 80 ° C. for 20 minutes to form a 0.7 μm charge generation layer. 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 = 31 ux · sec V ₁₂ = 20 V Example 2 The following formula (C) In a ball mill, 200 parts of the compound of Exemplified Compound No. 18, 5 parts of sodium acetate, 200 parts of a polyester resin (trade name “Vylon 200” manufactured by Toyobo) and 20,000 parts of tetrahydrofuran are mixed by grinding with a ball mill. The plate was coated with a wire bar and dried to form a charge generation layer of about 1 μm. 1 part of the compound of the formula (B) is formed on the charge generation layer,
Polycarbonate resin (trade name “Panlite K-1300”
A solution prepared by dissolving 1 part of Teijin Chemical Co., Ltd. in 10 parts of chloroform was applied using a wire bar and dried at 80 ° C. for 30 minutes to form a charge transport layer having a thickness of about 18 μm, as shown in FIG. A laminated electrophotographic photoreceptor was prepared.

The sensitivity of this photoreceptor was E 1/2 = 0.61 ux · sec V ₁₂ = 1 V.

Production Example 2 [Production of Compound of Formula (C)] 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,
20 ml of 1,3-dimethyl-2-imidazolidinone (DMI) was added and reacted at 80 to 90 ° C. for 8 hours. After cooling to room temperature, water
30 ml was added. After filtration, washing with methanol and drying, 6.1 g of a compound of the following formula was obtained.

5.0 g of this coupler compound 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 solution 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. Acetic acid
10 ml was added, followed by filtration, washing with N, N-dimethylformamide, acetone, methanol and water in this order. Drying yielded 3.6 g of a black powder (melting point 270 ° C. or higher). This was confirmed to be Exemplified Compound No. 18 by elemental analysis and infrared absorption spectrum.

Elemental analysis value CHN calculated value (%) 71.59 3.71 9.11 observed value (%) 71.20 3.62 9.08 The infrared absorption spectrum (KBr method) of this compound was measured for 3rd.
Shown in the figure.

Comparative Example 2 0.5 part of a polyester resin (“Vylon 200”), 0.5 part of the compound (C) and 50 parts of tetrahydrofuran were pulverized and mixed by a ball mill, and the obtained dispersion was applied to an aluminum plate using a wire bar at 80 ° C. And dry for 20 minutes.
A μm charge generation layer was formed. A charge transport layer was formed on this charge generation layer in the same manner as in Example 2. The sensitivity of the obtained photoreceptor was E 1/2 = 1.51 ux · sec V ₁₂ = 20 V.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a configuration example of an electrophotographic photosensitive member. In FIG. 1, each symbol is as follows. DESCRIPTION OF SYMBOLS 1 ... Conductive support 2 ... Charge generation layer 3 ... Charge transport layer 4 ... Photosensitive layer Fig. 2 shows the infrared absorption spectrum (KBr) of Exemplified Compound No. 3
Method). FIG. 3 shows the infrared absorption spectrum (KBr) of Exemplified Compound No. 18.
Method).

Claims (5)

(57) [Claims] An electrophotographic photoreceptor of a stacked type comprising a charge generation layer and a charge transport layer, wherein the charge generation layer contains an azo compound and sodium acetate. 2. The azo compound contained in the charge generation layer is represented by the following general formula (I): [In the formula (I), Ar ¹ represents a divalent to tetravalent aromatic linking group, and Y represents a hydrogen atom, a hydroxy group, an amino group, a carbamoylamino group, an aliphatic amino group, an aromatic amino group, an aromatic amino group. X represents an organic residue condensed with a benzene ring to form an aromatic hydrocarbon ring or an aromatic heterocyclic ring; R represents a hydrogen atom, a halogen atom or a hydroxyl group; The electrophotographic photosensitive member according to claim 1, which is a compound represented by the following formula: 3. The azo compound contained in the charge generation layer has the following general formula (II): [In the formula (II), Y represents a hydrogen atom, a hydroxy group, an amino group, a carbamoylamino group, an aliphatic amino group, an aromatic amino group, or an aromatic aminocarbonylamino group]. The photoconductor for electrophotography according to the above. 4. The electrophotographic photoconductor according to claim 1, wherein the ratio of the azo compound and sodium acetate contained in the charge generation layer is 10,000 to (5 to 1,000) by weight. 5. The charge transport material contained in the charge transport layer is represented by the following general formula (III): [In the formula (III), Ar ² , Ar ³ , and Ar ⁴ represent an alkyl group, an aromatic hydrocarbon group, or an aromatic heterocyclic group, and m represents an integer of 1 to ^3. ] Item 6. An electrophotographic photosensitive member according to Item 3.