JPH0373959A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To obtain an electrophotographic sensitive body having satisfactory sensitivity and high durability by incorporating at least one kind of specified trisazo compd. into a photosensitive layer on an electrically conductive support. CONSTITUTION:At least one kind of trisazo compd. represented by formula I (where A is a residue of a coupler) as an electric charge generating material 2 is incorporated into a photosensitive layer 4 on an electrically conductive support 1. The photosensitive layer 4 may be formed on the support 1 by dispersing the electric charge generating material 2 and an electric charge transferring material 3 in a binder. An electrophotographic sensitive body having high sensitivity and superior performance is easily produced. The performance is not deteriorated even after repeated use.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a photoreceptor for electrophotography. More specifically, the present invention relates to an electrophotographic photoreceptor comprising a photosensitive layer on a conductive support containing a novel trisazo compound as a charge generating substance.

[Conventional technology]

Conventionally, inorganic photosensitive materials such as selenium, cadmium sulfide, and zinc oxide have been widely used as photosensitive materials for electrophotographic photoreceptors. However, photoreceptors using these photosensitive materials do not fully satisfy the performance requirements for electrophotographic photoreceptors such as sensitivity, photostability, moisture resistance, and durability. Photoreceptors using photoreceptors have excellent sensitivity, but they tend to crystallize due to heat or adhesion of dirt, resulting in deterioration of the photoreceptor characteristics.Furthermore, since they are manufactured by vacuum deposition, they are expensive and lack flexibility. Therefore, it also has many drawbacks such as difficulty in processing it into a belt shape. Photoreceptors using cadmium sulfide-based materials have problems in moisture resistance and durability, and photoreceptors using zinc oxide have problems in durability.

In order to overcome the drawbacks of photoreceptors using inorganic photosensitive materials, various photoreceptors using organic photosensitive materials have been studied.

For example, as an organic photosensitive material that has been partially put into practical use,
．． A combination of 7-trinitro-9-fluorenone and poly-N-vinylcarbazole is known. However, photoreceptors using this method had low sensitivity and were not satisfactory in terms of durability.

In recent years, among photoreceptors developed to improve the above-mentioned drawbacks, a functionally separated photoreceptor in which charge generation function and charge transport function are shared by separate substances has been attracting attention. In this functionally separated type photoreceptor, materials having respective functions can be selected from a wide range of materials and combined, so that it is possible to produce a highly sensitive and highly durable photoreceptor. Many materials have been proposed as charge generating materials for use in such functionally separated photoreceptors.

Among these, photoreceptors using organic dyes or organic pigments as charge-generating substances have attracted particular attention in recent years. For example, a photoreceptor using a disazo pigment having a styrylstilbene skeleton (
JP-A-53-133445), a photoreceptor using a disazo pigment having a carbazole skeleton (JP-A-53-950)
No. 33), a photoreceptor using a trisazo pigment having a triphenylamine skeleton (Japanese Patent Application Laid-open No. 132347/1983),
A photoreceptor using a disazo pigment having a distyrylcarbazole skeleton (Japanese Patent Application Laid-open No. 14967/1989), a photoreceptor using a disazo pigment having a bisstilbene skeleton (Japanese Patent Application Laid-open No. 17733/1987), etc. have been reported. . but,
These electrophotographic photoreceptors do not necessarily fully satisfy the required performance, and there has been a desire to develop an even better photoreceptor.

[Problem to be solved by the invention]

An object of the present invention is to provide an electrophotographic photoreceptor having sufficient sensitivity and good durability, and to provide a novel organic charge-generating substance for use therein.

[Means to solve the problem]

The present inventors have made extensive studies to solve the above problems, and
As a result, a new trisazo compound represented by the general formula (I) (wherein A represents a coupler residue) has superior properties such as high sensitivity and high durability compared to existing azo compounds. The present invention was based on the discovery that an electrophotographic photoreceptor having the following characteristics can be provided.

That is, the present invention is characterized in that the photosensitive layer on the conductive support contains at least one trisazo compound represented by the general formula (I) (wherein A represents a coupler residue). This is a photoreceptor for electrophotography.

In general formula (I), A represents a coupler residue,
Examples of this residue include the following a) to d).

a) Coupler residue of general formula (n) (wherein, X is an optionally substituted hydrocarbon ring, an optionally substituted heterocycle, and Y is R1R4, where R+ is a good hydrocarbon ring group, an optionally substituted heterocyclic group, R1 is hydrogen, an optionally substituted alkyl group, an optionally substituted phenyl group, R1 is an optionally substituted hydrocarbon ring group , an optionally substituted heterocyclic group or an optionally substituted styryl group, R4 represents hydrogen, an alkyl group, or an optionally substituted phenyl group, and R5 and R1 represent a ring together with the carbon atoms bonded to them. ) In general formula (II), X may specifically be a hydrocarbon ring such as a naphthalene ring or anthracene ring condensed with a benzene ring to which a hydroxyl group and Y are bonded, or an indole ring; Examples include heterocycles such as a carbazole ring, benzocarbazole ring, and dibenzofuran ring.

In addition, when X has a substituent, the substituent is a chlorine atom,
Examples include halogen atoms such as bromine atoms and hydroxyl groups.

The ring group for R2 or R1 is a hydrocarbon ring group such as phenyl group, naphthyl group, anthryl group, pyrenyl group, or pyridyl group, thienyl group, furyl group, indolyl group, benzofuranyl group, carbazolyl group, dibenzofuranyl group. Examples of such heterocyclic groups include a fluorene ring and the like, and examples of the ring in which R1 and R1 are bonded together include a fluorene ring.

When R or R1 is a cyclic group having a substituent, the substituent includes an alkyl group such as a methyl group, an ethyl group, a propyl group, a butyl group, an alkoxy group such as a methoxy group, an ethoxy group, a propoxy group, a butoxy group, Examples include halogen atoms such as chlorine atoms and bromine atoms, halomethyl groups such as trifluoromethyl groups, dialkylamino groups such as dimethylamino groups and diethylamino groups, nitro groups, cyano groups, carboxyl groups, and esters thereof.

When R2 is an optionally substituted phenyl group, examples of the substituent include halogen atoms such as chlorine atom and bromine atom.

b) Coupler residue (III) of general formula (III) or (IV) (■) (In both formulas, R3 represents a substituted or unsubstituted hydrocarbon group.) Specifically, R2 is a methyl group. Examples include alkyl groups such as , ethyl group, propyl group, butyl group, and octyl group, and alkoxyalkyl groups such as methoxyethyl group and ethoxyethyl group.

C) Coupler residue 1 of general formula (V) (wherein R8 represents an alkyl group, carbamoyl group, carboxyl group, or an ester group thereof, and R7 represents an optionally substituted hydrocarbon ring group) R1 Specific examples include hydrocarbon ring groups such as phenyl group and naphthyl group, and when these groups have substituents, alkyl groups such as methyl group, ethyl group, propyl group, butyl group, etc. group, methoxy group, ethoxy group, propoxy group,
Alkoxy groups such as butoxy groups, dialkylamino groups such as dimethylamino groups and diethylamino groups, chlorine atoms,
Examples include halogen atoms such as bromine atoms, nitro groups, and cyano groups.

d) Coupler residue (■) of general formula (V1) or (■)
(■) (In both formulas, Z represents an optionally substituted divalent group of a hydrocarbon ring or a divalent group of an optionally substituted heterocyclic ring.) Specifically, Z is 0. - Divalent groups of monocyclic aromatic hydrocarbons such as fluorene rings, 0-naphthylene groups, per
+-Naphthylene group, 1,2-anthraquinonylene L
A divalent group of a fused polycyclic aromatic hydrocarbon such as a 9,10-phenanthrylene group, or a 3.4 pyrazolediyl group,
Heterocyclic divalent groups such as 2,3-pyridinediyl group, 4,5-pyrimidinediyl group, 6,7-ydazolediyl group, 5,6-penzidazolediyl group, 6,7-quinolinediyl group, etc. I can give an example. When these ring groups have a substituent, examples of the substituent include alkyl groups such as methyl, ethyl, propyl, and butyl, alkoxy groups such as methoxy, ethoxy, propoxy, and butoxy, and dimethyl. Examples include dialkylamino groups such as amino groups and diethylamino groups, halogen atoms such as chlorine atoms and bromine atoms, nitro groups, and cyano groups.

Among the above-exemplified Kambler residues, the photosensitivity is high;
The coupler residue represented by the general formula (It) is most preferred because intermediate raw materials are easily available and it can be produced at low cost.

More specific examples of the trisazo compound used in the present invention include those represented by the following structural formula.

In addition, the structural formula is shown only by the camplar residue portion in general formula (I).

H3 Song F H3 The compound used in the present invention can be produced using the following method.

It can be easily produced by diazotizing the amine compound represented by formula (■), then isolating the diazotized compound as it is or as a borofluoride salt, and then coupling it with the coupler compound.

The electrophotographic photoreceptor of the present invention contains at least one trisazo compound represented by the general formula (I) as a charge generating substance in a photosensitive layer on a conductive support.

Typical configurations of such photoreceptors are shown in FIGS. 3 and 4. What is shown in FIG. 3 is 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. The photosensitive N4 is a laminated type photosensitive material consisting of a charge generation layer 6 in which a charge generation substance is dispersed in a binder and a charge transport layer 5 in which a charge transport substance is dispersed in a binder on a conductive support 1.
It is a photoreceptor equipped with

Other examples include those in which the charge generation layer and 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 shown in FIG. 4, imagewise exposed light passes through the charge transport layer, and a charge generation substance generates charges in the charge generation layer. The charged charges are injected into the charge transport layer, and the charge transport material transports the charges.

The electrophotographic photoreceptor of the present invention contains, in addition to the trisazo compound of general formula (I), a conductive support, a binder, a charge transport material, etc., and other components of the photoreceptor include the photoreceptor. It is not particularly limited as long as it functions as a component of.

That is, the conductive support used in the photoreceptor of the present invention includes a metal plate made of aluminum, copper, zinc, etc., a plastic sheet or plastic film made of polyester, etc., on which a conductive material such as aluminum or Snow is deposited, or Conductive treated paper, resin, etc. are used.

As binders, vinyl polymers such as polystyrene, polyacrylamide, and poly-N-vinylcarbazole, and condensation resins such as polyamide resins, polyester resins, epoxy resins, phenoxy resins, and polycarbonate resins are used. Any resin that is adhesive to the body can be used.

Charge transport materials are generally classified into two types: charge transport materials and electron transport materials, and both can be used in the photoreceptor of the present invention. In addition to electron-accepting substances that easily transport electrons, such as trinitrofluorenone or tetranitrofluorenone, poly-N-
Polymers containing heterocyclic compounds such as vinyl carbazole, triazole derivatives, oxadiazole derivatives, imidazole derivatives, birapurine derivatives,
Examples include electron-donating substances that easily transport holes, such as polyarylalkane derivatives, phenylenediamine derivatives, hydrazone derivatives, amino-substituted chalcone derivatives, triarylachaene derivatives, carbazole derivatives, and stilbene derivatives.

For example, 9-ethylcarbazole-3-aldehyde-
1-Methyl-1-phenylhydrazone, 9-ethylcarbazole-3-aldehyde-1benzyl-phenylhydrazone, 9-ethylcarbazole-3-aldehyde-1
, 1-diphenylhydrazone, 4-diethylaminostyrene-β-aldehyde-1-methyl-1-phenylhydrazone, 4-methoxynaphthalene-1-aldehyde-1
Benzyl-phenylhydrazone, 4-methoxybenzaldehyde-1-methyl-1-phenylhydrazone, 2.
4-Dimethoxybenzaldehyde-1-benzyl-phenylhydrazone, 4-diethylagonobenzaldehyde 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-diethylaminophenyl)propane, tris(4-diethylachnophenyl)
Methane, 2.2'-dimethyl-4,4'-bis(diethylamino)-triphenylmethane, 9-(4-diethylaminostyryl)anthracene, 9-bromo-10-
(4-diethylaminostyryl)anthracene, 9-(
4-dimethylaminobenzylidene) fluorene, 1-(
9-fluorenylidene)-9-ethylcarbazole, l
, 2-bis(4-diethylaminostyryl)benzene,
1.2-bis(2,4-dimethoxystyryl)benzene, 3-styryl-9-ethylcarbazole, 3-(4-
methoxystyryl)-9-ethylcarbazole, 4-diphenylagonostilbene, 4-dibenzylaminostilbene, 4-ditolylaminostilbene, 1-(4-diethylaminostyryl)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 transport 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-oxazole, 2-vinyl-4-(2-chlorophenyl)-5
-(4-diethylaminophenyl)oxazole, 2(
4-diethylaminophenyl)-4-phenyloxazole, 9-(3-(4-diethylaminophenyl)-
2-probenyritin)-9H-xanthine, poly-N-
Vinyl carbazole, halogenated poly-N-vinyl carbazole, polyvinylpyrene, polyvinylanthracene, pyrene formaldehyde resin, ethyl carbazole formaldehyde resin, and the like.

Examples of the electron transport substance include chloranil, bromoanil, tetracyanoethylene, tetracyanoquinodimethane, 2.4.7-) dinitro-9-fluorenone, 2,4,5.7-tetranitro-9-fluorene, 2.
, 4.5.7-tetranitroxanthone, 2.4.8-
1-linitrothioxanthone, 2.6.8-trinitro-4H-indeno(I,2-b)thiophen-4-one, 1,3.7-)linitrodibenzothiophene-5,
Examples include 5-dioxide.

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

An intermediate layer can be provided between the photosensitive layer and the conductive support if necessary, and suitable materials include polyamide, nitrocellulose, casein, polyvinyl alcohol, etc., and the film thickness is preferably 111 m or less.

Conventionally known methods can be used to manufacture the photoreceptor. For example, in a laminated photoreceptor, fine particles of an azo compound are dispersed in a solution containing a binder, coated on a conductive support, and dried to obtain a charge generation layer. A charge transport layer can be created by coating and drying. Other methods can also be used to make the charge generating layer. For example, there is a method of vacuum-depositing azo pigments, or a method of applying and drying a solution of azo pigments, but the former is expensive, and the latter is generally difficult to handle with organic amines such as ethylenediamine, n-
Since there are some disadvantages in production, such as the use of -butylamine, etc., a coating method using a fine particle dispersion of an azo compound is preferred.

The application method is the usual means, for example, doctor blade,
Perform with dipping, wire bar, etc. The optimal range of the thickness of the photosensitive layer differs depending on the type of photoreceptor.

For example, in the photoreceptor shown in FIG. 3, the thickness is preferably 3 to 50 μm, more preferably 5 to 30 μm.

Further, in the photoreceptor shown in FIG. 4, the charge generation layer 6
The thickness is preferably 0.01 to 5 μm, more preferably 0.05 to 2 μm. If the thickness is less than 0.01 μm, charge generation will not be sufficient, and if it exceeds 5 μm, the residual potential will be high and it is not preferred for practical use. The thickness of the charge transport layer 5 is preferably 3 to 50 um, more preferably 5 to 30 um. If the thickness is less than 3 um, the amount of charge will be insufficient, and if it exceeds 50 um, the residual potential will be too high to be practical. is not desirable.

The content of the trisazo compound represented by general formula (I) in the photosensitive layer varies depending on the type of photoreceptor, but in the photoreceptor shown in FIG. 3, it is preferably 50% by weight in the photosensitive layer 4.
The content is preferably 20% by weight or less. Further, the charge transport material in this layer is preferably 10 to 95% by weight,
More preferably, it is contained in a proportion of 30 to 90% by weight. Further, in the photoreceptor shown in FIG. 4, the proportion of the trisazo compound in the charge generation layer 6 is preferably 30% by weight, more preferably 50% by weight or more. Further, the charge transport layer 5 contains a charge transport substance in an amount of 10 to 95% by weight, preferably 30 to 90% by weight. It should be noted that if the amount of the charge transport material in this layer is less than 10% by weight, hardly any charge will be transported, and if it exceeds 95% by weight, the mechanical strength of the photoreceptor will be poor, which is not preferred in practice.

[Action and effect]

The electrophotographic photoreceptor of the present invention is easy to manufacture by using a trisazo compound represented by the general formula (N) as a charge generating substance, has high sensitivity, and has excellent performance that does not deteriorate with repeated use. .

〔Example〕

EXAMPLES Hereinafter, the present invention will be specifically explained with reference to Examples, but the embodiments of the present invention are not limited thereby.

Production Example 1 4.0 g of the amine compound represented by the formula (■) above was added to 35
% hydrochloric acid and 80 d of water, and stirred at room temperature for 2 hours. After cooling to 0°C, a solution of 4.2 g of sodium nitrite dissolved in 20 rttl of water was added dropwise, and the mixture was stirred at the same temperature for 1 hour. After removing some insoluble materials, 20 d of 42% borofluoric acid was added, and the precipitated crystals were collected by filtration and dried to give 7.5 g of hexazonium borofluoride salt.
I got it.

N,N-dimethylformamide 40011! 7.2 g of a coupler compound represented by the following structural formula was dissolved in 0 to 5
Cooled to 'C. To this, 4.0 g of the above-mentioned hexazonium borofluoride salt was added and dissolved. Next, a solution of 3.3 g of sodium acetate dissolved in 50 °C of water was added dropwise at 0 to 5°C, stirred at the same temperature for 30 minutes, and then stirred at room temperature for 3 hours. The deposited precipitate was collected by filtration, loosened in N,N dimethylformamide 2QM (Sranodj operation), and then filtered. After repeating this sludge operation three times, washing with water and drying, 7.3 g of the trisazo compound of the exemplified metal A-9 (
A yield of 88.7%) was obtained. The obtained powder exhibited a spicy black color and did not melt at temperatures below 300'C.

It was confirmed by elemental analysis and infrared absorption spectrum (KBr method) that it was the desired product.

Elemental analysis value: CI (N C1 actual value (%)
69.78 3.46 10.22 8.56 Calculated value (%) 69.5B 3.59 10.29 8
．． 70 Infrared absorption spectrum i> Absorption 1 based on C=O
670c+o-' infrared absorption spectrum (KBr method) is shown in FIG.

Production Example 2 9.2 g of a coupler compound represented by the following structural formula was hot-dissolved in 600 d of N,N-dimethylformamide. A solution of 2.5 g of sodium acetate dissolved in 35 d of water was added at 90°C, and then cooled to 0-5°C. 3.0 g of the hexazonium borofluoride salt produced in Production Example 1 was gradually added at 0 to 5°C, stirred at the same temperature for 30 minutes, and then stirred at room temperature for 4 hours to complete the reaction. It was taken out in the same manner as in Production Example 1 to obtain 8 g (yield: 82.9%) of Exemplary Compound A-1536. The obtained powder exhibited a black color and did not melt at temperatures below 300°C.

It was confirmed by elemental analysis and infrared absorption spectrum (KBr method) that it was the desired product.

Elemental analysis value: CHN C1 actual value (%) 6
5.60 3.00 13.05 6.24 Calculated value (%
) 65.66 3.07 12.91 6.55 Infrared absorption spectrum; Absorption based on >C=O 1670
c++-' infrared absorption spectrum (KBr method) is shown in FIG.

Example 1 0.5 parts of polyester resin (trade name "Vylon 200" manufactured by Toyobo), 0.5 parts of Exemplary Compound A-9, and 50 parts of tetrahydrofuran were ground and mixed in a ball mill, and the resulting dispersion was placed on an aluminum plate. Apply using a wire bar,
It was dried at 80° C. for 20 minutes to form a charge generation layer with a thickness of about 1 μm. On this charge generation layer, 1 part of a hydrazone compound represented by the following structural formula, a polycarbonate resin (trade name "Panlite ni-1300," manufactured by Kijin Kasei Co., Ltd.)
A solution of 1 part dissolved in 10 parts of chloroform was applied using a wire bar and dried at 80"C for 30 minutes to a thickness of about 1.
A charge transport layer having a thickness of 8 μm was formed, and a laminated photoreceptor shown in FIG. 4 was produced.

Electrostatic copying paper test equipment W, (Kawaguchi Electric Seisakusho model EP
A-8100>, the photoreceptor is charged by corona discharge with an applied voltage of -6 KV, the surface potential vo at that time is measured, and then the surface potential at that time is measured by leaving it in a dark place for 2 seconds.
Then, with the surface illuminance of the photoconductor at 5 lux, irradiate it with light from a halogen lamp (color temperature 2856°K), measure the time for the surface potential to reach 172 of Vt, and calculate the half-reduced exposure amount. E1/2 (lux-sec) was calculated. Furthermore, the surface potential v1□, ie, the residual potential, was measured after 10 seconds of light irradiation.

Examples 2 to 10 Photoreceptors were prepared in the same manner as in Example 1 using the compound of the present invention as a charge generating substance and the compound represented by the following structural formula as a charge transporting substance, and E1/2 was determined. .

The charge generating substance, charge transporting substance and El/2 used are shown in Table 1 together with Example 1.

(CT-2> (CT-3) Comparative Example 1 Photosensitivity was carried out in the same manner as in Example 1 except that a disazo compound represented by the following structural formula described in Japanese Patent Publication No. 55-42380 was used as the charge generating substance. The body was created.

E 1/2 was 12.0 (Iux-see).

Example 11 The photoreceptor produced in Example 7 was attached to a commercially available electrophotographic copying machine to make copies, and even on the 10,000th copy, a clear image faithful to the original and free from fogging was obtained.

As described above, it can be said that the electrophotographic photoreceptor using the trisazo compound of the present invention has high sensitivity and stable performance upon repeated use, and is also excellent in durability.

The photoreceptor of the present invention can be used not only in electrophotographic copying machines, but also in various printers, electrophotographic engraving systems, etc. that apply electrophotographic copying principles.

[Brief explanation of drawings]

Figures 1 and 2 show exemplary compounds A-9 and A-15, respectively.
3 is a diagram showing the infrared absorption spectrum (KBr method) of No. 3. FIGS. 3 and 4 are cross-sectional views showing an example of the structure of an electrophotographic photoreceptor. Note that in FIGS. 3 and 4, the respective symbols are as follows. DESCRIPTION OF SYMBOLS 1...Electroconductive support 4...Photosensitive layer 2...Charge generating substance 5...Charge transport layer 3...Charge transport substance 6
...indicates a charge generation layer. Transmittance (%)

Claims (1)

[Claims] 1) The photosensitive layer on the conductive support has the general formula (I)▲mathematical formula,
There are chemical formulas, tables, etc. ▼(I) (In the formula, A represents a coupler residue.) An electrophotographic photoreceptor characterized by containing at least one trisazo compound represented by the following.