JPH0311356A - Photosensitive body - Google Patents

Abstract

PURPOSE:To improve electrostatic characteristics, particularly the photosensitivity by incorporating a specific azo pigment into the photosensitive body. CONSTITUTION:This photosensitive body is formed with a photosensitive layer 4 formed by compounding a photoconductive material 3 and a charge transfer material 2 with a binder on a base body 1 and the photosensitive layer 4 contains the azo pigment expressed by formula I. In the formula, R1, R2, R1', R2' denote hydrogn, alkyl group, alkoxy group, halogen atom, cyano group, alkoxycarbonyl group; Cp1, Cp2 denote a residual coupler group having a pheno lic OH group. The photosensitive body which is excellent overall in the electro static characteristics and has the particularly excellent sensitivity is obtd. in this way.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a photoreceptor used in electrophotography, and more particularly, to a photoreceptor having a photosensitive layer containing a novel azo pigment.

BACKGROUND ART Conventionally, in photoconductors used in electrophotography and the like, inorganic photoconductive materials such as selenium, cadmium sulfide, and zinc oxide have been known as materials constituting photosensitive layers.

Although these inorganic photoconductive materials have many advantages, such as less charge dissipation in the dark or the ability to rapidly dissipate charge by light irradiation,
It has various drawbacks.

For example, selenium-based photoreceptors require difficult manufacturing conditions, are expensive to manufacture, and must be handled with care because they are susceptible to heat and mechanical shock. Furthermore, with zinc oxide photoreceptors and cadmium sulfide photoreceptors, stable sensitivity cannot be obtained in humid environments, and the dye added as a sensitizer causes charging deterioration due to corona charging and photofading due to exposure. For,
It has the disadvantage that it cannot provide stable characteristics over a long period of time.

On the other hand, the use of various organic photoconductive polymers including polyvinylcarbazole as materials constituting the photosensitive layer has also been considered. However, although these organic photoconductive polymers are superior to the above-mentioned inorganic photoconductive materials in terms of film formability and light weight, they still lack sufficient sensitivity, durability, and stability due to environmental changes. In this respect, it was inferior to inorganic photoconductive materials.

Therefore, in recent years, various research and development efforts have been carried out to solve the drawbacks and problems of these photoreceptors.
1! A laminated or dispersed functionally separated photoreceptor has been developed in which the charge generation function and the charge transport function are assigned to separate substances, respectively.

Such functionally separated photoreceptors have a wide range of materials to choose from, and can combine the best materials in terms of electrophotographic properties such as charging characteristics, sensitivity, residual potential, repeatability, and printing durability. This makes it possible to provide a high-performance photoreceptor. Furthermore, since it can be produced by coating, it is possible to provide a photoreceptor with extremely high productivity and at low cost, and furthermore, by appropriately selecting the charge generating material, the sensitive wavelength range can be freely controlled. For example, charge generating materials include phthalocyanine pigments, cyanine pigments, polycyclic quinone pigments, perylene pigments, perinone pigments, indigo dyes,
Organic pigments and dyes such as thioindigo dyes and squalium pigments, and inorganic materials such as selenium, selenium/arsenic, selenium/tellurium, cadmium sulfide, zinc oxide, and amorphous silicon can be used.

However, even with such functionally separated photoreceptors, it is still not easy to obtain one that satisfies overall electrostatic properties.
Sensitivity is still not sufficient, and a photoreceptor with even better sensitivity and better overall electrostatic properties has become desirable.

Problems to be Solved by the Invention This invention was made in view of the above circumstances, and its object is to provide a photoreceptor that has excellent electrostatic properties in general and sensitivity in particular.807 .

Means for Solving the Problems The present invention provides a photoreceptor characterized by having a photosensitive layer containing an azo pigment represented by the following general formula [I] on a conductive support; Indicates an alkoxycarbonyl group of Cl-C2.

R6 and R2 are preferably electron-withdrawing groups, particularly preferably cyano groups.

In general formula [1], Cpt, Cp! is a coupler residue having a phenolic OH group, for example, the following general formula [II]
Those represented by ~[XI] can be used, and the coupler components Cpl and Cpt may be the same or different.

(Hereinafter, blank spaces) In formula 1, R1, R2, R, l, RlI represent hydrogen, an alkyl group, an alkoxyl group, a halogen atom, a cyano group, an alkoxycarbonyl group; C1) t, Cp are phenolic OH groups may be different. ] Regarding.

General formula], R11Rz, R, □, R2'' are each a hydrogen atom, a C1-C2 alkyl group, a C1-C2 alkoxy group, a halogen atom (fluorine, chlorine, one unit [II[] [■] [ II] [IV] [V] ・2・ [VI] [■] [X] [I[] [Wherein, X is oxygen, sulfur, or a nitrogen atom that may have a substituent; Y is aromatic A divalent group of a hydrocarbon or a divalent group that forms a heterocycle together with a nitrogen atom; 2
is a residue that is fused with a benzene ring to form a polycyclic conjugated ring or a heterocycle; R1, R@, R7, R, , R
,,1R,! , R13 is hydrogen or an alkyl group which may have a substituent.

an aralkyl group, an aryl group, or a heterocyclic group, each of which may be taken together to form a ring; Represents a cyclic group; R, R9 represents hydrogen, a halogen atom, an alkyl group that may have a substituent, an aralkyl group, an anlu group, an alkoxycarbonyl group, an aryl group, a fused polycyclic group, or a hetero Represents a ring group; RISxR1@ and RI7, R11 are hydrogen, halogen atom, alkyl group, nitro group, substituted sulfone group, N
- Represents an optionally substituted carbamoyl group or sulfamoyl group, or an optionally substituted C-acylamino group or phthalimidyl group % RIS, R14 and RI7 to R1 may be combined to form a ring. In particular, the above general formula 口口, [IV], [■], [■], [
In the coupler component of [II], R3, R1゜,
R1□ is hydrogen, R7, Ro, Rlm, R14
is preferably a substituted phenyl represented by the following general formula: [wherein R1 is a substituent selected from halogen, nitro, cyano, and trifluoromethyl group].

The coupler components used in this invention include:
Specifically, those having chemical formulas [11 to [30]σ shown below may be mentioned, but are not particularly limited to these.

[1F [2] [3] [4] [7] [9] [161 [18] [8] [10F [17] [191 [11] [12] [131 [14] O [15] [221 [ 23] [241 [25] [26] [27] [28] [29] Here, the azo pigment represented by the above general formula [I] of the present invention can be easily synthesized by a conventional method.

That is, a diamino compound represented by the following general formula [XI[] [wherein R,, R,, R, l, and R3' have the same meanings as in the case of [I] above 1] was prepared using sodium nitrite-hydrochloric acid. diazotization using the above general formula [
11] to [XI], or diazotize the diamino compound, add an acid such as HBF, isolate it in the form of a salt, and then perform the coupling reaction. It can be synthesized by doing the following. Incidentally, the coupling is usually carried out according to a known method.
The reaction is carried out in water and/or an organic solvent such as N,N-dimethylformamide at a reaction temperature of 30 to 25° C. for 1 to 10 hours.

Further, the diaminated metal represented by the general formula [I[] can be prepared by a known method.

For example, first, as shown in the general formula below, the general formula [XI
The dinitronaphthalic anhydride represented by [I] and the 1,2-diaminoethylene compound represented by the general formula [XrV] are dehydrated and condensed using a catalyst such as acetic acid to form a compound represented by the general formula [XV]. Synthesize the dinitro compounds shown.

[XV] Then, this dinitro compound [XV] is reduced by a known method by zinc-calcium chloride, tin chloride-hydrochloric acid, acetic acid-iron, sodium hydrosulfide, sodium sulfide, hydrazine, etc., or by hydrogenation to obtain the general formula A diamino compound represented by [Xn] is obtained.

[XV] [XII] In the photoreceptor according to the present invention, when forming the photosensitive layer on the conductive support, the azo pigment represented by the general formula [11] prepared as described above is added to the photosensitive layer. 1
Or contain two or more types.

■ In this way, when the photosensitive layer contains one or more azo pigments represented by the general formula [I], this azo pigment acts as a photoconductive substance, and when it absorbs light, it becomes a charge carrier with extremely high efficiency. As a result, the sensitivity of the photoreceptor is improved.

Although the generated charge carriers can be transported using this azo pigment as a medium, it is more effective to transport them using a charge transporting material as a medium.

Here, the conductive support used for this photoreceptor may be a sheet or drum-shaped foil or plate of metal or alloy such as copper, aluminum, silver, iron, or nickel;
These metals are attached to a plastic film by vacuum deposition, electroless plating, etc., or a layer of a conductive compound such as a conductive polymer, indium oxide, or tin oxide is attached to a support such as paper or a plastic film. A material formed by coating or vapor deposition can be used.

Further, various types of photoreceptors are known, and the photoreceptor of the present invention may be any of them.

For example, as shown in FIG. 1, a photoconductive material (3) and a charge transport material (2
) with a binder to form a photosensitive layer (4), or as shown in FIG. 2, a photosensitive layer formed on a conductive support (1), A functionally separated laminated photoreceptor in which a charge generation layer (6) containing a photoconductive material (3) and a charge transport layer (5) containing a charge transport material (2) are laminated in order; As shown in FIG. 3, the photosensitive layer formed on the conductive support (1) is connected to the charge transport layer (5) containing the charge transport material (2), contrary to the case shown in FIG. It may be a functionally separated layered photoreceptor in which a charge generation layer (6) containing a conductive material (3) is laminated one after another.

Furthermore, as shown in FIG. 4, a surface protective layer (7) is provided on the surface of the photosensitive layer (4), and as shown in FIG. ) and the middle class (8
) may be provided. In addition, if an intermediate layer is provided between the conductive support and the photosensitive layer as shown in Figure t$5, it is possible to improve the adhesion and coating properties between the conductive support and the photosensitive layer. , it becomes possible to improve the protection of the conductive support and the injection of charge from the conductive support to the photosensitive layer. Further, such a surface protective layer and an intermediate layer can also be provided in the functionally separated type laminated photoreceptor described above.

First, a case will be described in which a single-layer type photoreceptor as shown in FIG. 1 is manufactured as a photoreceptor according to the present invention.

In this case, fine particles of the azo pigment represented by the above general formula [13] are dispersed in a resin solution or a solution containing a charge transport compound and a resin, coated on a conductive support, and dried. Let them do it. At this time, the thickness of the photosensitive layer is set to 3 to 30 microns, preferably 5 to 20 microns. Furthermore, if the amount of the azo pigment used is too small, the sensitivity will be poor, and if it is too large, the charging property will be poor and the mechanical strength of the photosensitive layer will be weakened. 0.01 to 2 parts by weight,
The amount is preferably in the range of 0.2 to 1.2 parts by weight. In addition, when using a charge transporting material which itself can be used as a binder, such as polyvinyl carbazole, the amount of the azo pigment added is 0°O1 to 0.5% by weight per 1 part by weight of the charge transporting material. It is preferable that the

Next, as a photoreceptor according to the present invention, a case will be described in which a laminated type photoreceptor as shown in FIG. 2 is manufactured.

In this case, the above-mentioned azo pigment is vacuum-deposited on the conductive support, dissolved in a solvent such as amine, or applied in a suitable solvent or a solution in which a binder resin is dissolved as necessary. A coating liquid in which the above azo pigment is dispersed is applied onto a conductive support and dried to form a charge generation layer on the conductive support. In this case, the thickness of this charge generation layer is set to be 4 μm or less, preferably 2 μm or less.

Then, a solution containing a charge transport material and a binder is applied onto the charge generation layer thus formed and dried to form a charge transport layer.

In this case, the thickness of the charge transport layer is 3 to 50 μm, preferably 5 to 30 μm. The proportion of the charge transport material is 0.2 to 2 parts by weight, preferably 0.3 to 1.3 parts by weight, based on 1 part by weight of the binder resin. Note that if the charge transport material is a polymeric charge transport material that itself can be used as a binder, no other binder resin may be used.

Here, the binder resin used to manufacture each photoreceptor as described above is electrically insulating, and may be a known thermoplastic resin, thermosetting resin, photocurable resin, photoconductive resin, etc. can. Suitable binder resins include, but are not particularly limited to, saturated polyester resins, polyamide resins, acrylic resins, ethylene-vinyl acetate copolymers, ionically crosslinked olefin copolymers (ionomers), Thermoplastic agents such as styrene-butadiene block copolymer, polycarbonate, vinyl chloride vinyl acetate copolymer, cellulose ester, polyimide, styrene resin, epoxy resin, urethane resin,
Thermosetting resins such as silicone resins, phenolic resins, melamine resins, xylene resins, alkyd resins, thermosetting acrylic resins, photocurable resins, polyvinyl carbazole,
Examples include photoconductive resins such as polyvinylpyrene, polyvinylanthracene, and polyvinylpyrrole. Note that these binder resins can be used alone or in combination. It is desirable that these electrical insulation properties have a volume resistivity of lXlO12Ω·6111 or more when measured alone.

In addition, in the photoreceptor of the present invention, in addition to the binder stmh as described above, a plasticizer such as halogenated paraffin, polychlorinated biphenyl, dimethylnaphthalene, dibutyl heptatarate, 〇-terphenyl, etc., chloranil, tetracyanoethylene, Electron-withdrawing sensitizers such as 4.7-dolinitrofluorenone, 5.6-dicyazbenzoquinone, tetracyanoquinodimethane, tetrachlorophthalic anhydride, 3.5-dinitrobenzoic acid, methyl violet, rhodamine B1 Sensitizers such as cyanine dyes, pyrylium salts, thiapyrylium salts, etc. may also be used.

In addition, charge transport materials used in the above photoreceptor include hydrazone compounds, pyrazoline compounds, styryl compounds, triphenylmethane compounds, oxadiazole compounds, carbazole compounds, stilbene compounds, enamine compounds, oxazole compounds, and triphenyl compounds. Various compounds such as amine compounds, tetraphenylbenzidine compounds, and azine compounds can be used. Specifically, for example, carbazole, N-ethylcarbazole,
N-vinylcarbazole, N-phenylcarbazole,
Tetracene, chrysene, pyrene, perylene, 2-phenylnaphthalene, azapyrene, 2゜3-benzochrysene,
3.4-benzopyrene, fluorene, 1.2-benzofluorene, 4-(2-fluorenylazo)resolunol, 2p-anisoleaminofluorene, p-diethylaminoazobenzene, cation, N,N-dimethyl-p
-7enylazoaniline, p-(dimethylamino)stilbene, 1,4-bis(2-methylstyryl)benzene, 9-(4-diethylaminostyryl)anthracene,
2.5-bis(4-diethylaminophenyl)-1,3
,5-oxadiazole, l-7enyl-3-(p-diethylaminostyryl)-5-(p-diethylaminophenyl)pyrazoline, I'uni-3-phenyl-5-pyrazolone, 2-(m-s7tyl)- 3-Phenyloxasheet 2-(p-diethylaminostyryl)-
6-Dinithylaminobenzoxazole, 2-(p-diethylaminostyryl)-6-dinithylaminobenzothiazole, bis(4-diethylamino-2-methylphenyl)phenylmethane, 1.1-bis(4-N,N -diethylamino-2-ethylphenyl)hebutane, NlN
-diphenylhydrazino-3-methylidene-1O-ethylphenoxazine, N,N-diphenylhydrazino-3
-Methylidene-10-ethylphenothiazine, 1.1.
2.2-tetrakis-(4-N.

N-diethylamino-2-ethylphenyl)ethane, p
-diethylaminobenzaldehyde-N,N-diphenylhydrazone, p-diphenylaminobenzaldehyde-N, N-diphenylhydrazone, N-ethylcarbazole- phenylhydrazone, p-'; ethylaminobenzaldehyde F-N-σ-su7thi-N -7 enylhydrazone,
p-diethylaminobenzaldehyde-3-methylbenzthiazolinone-2-hydrazone, 2-methyl-4-N
, N-diphenylamino-β-7enylstilbene, α
-7enyl-4-N,N-diphenylaminostilbene, 1. t-bis(P-diethylaminophenyl)-4,
Charge transport substances such as 4-diphenyl-1,3-butadiene are used alone or in combination of two or more.

In addition, when providing a surface protective layer as shown in Figure 4, the material may be a polymer such as acrylic resin, polyaryl resin, polycarbonate resin, or urethane resin, or a low-resistance compound such as tin oxide or indium oxide. A dispersed material is suitable, and an organic plasma polymerized film can also be used, and if necessary, oxygen,
It is also possible to include nitrogen, halogen, and atoms of Group I and Group V of the periodic table. The thickness of the surface protective layer is 5 μm.
m or less is desirable.

When providing an intermediate layer as shown in Figure 5, the material may be a polymer such as polyimide, polyamide, nitrocellulose, polyvinyl butyral, or polyvinyl alcohol, or a low-resistance compound such as tin oxide or indium oxide. Dispersed materials, vapor-deposited films of aluminum oxide, zinc oxide, silicon oxide, etc. are suitable. In this case, the thickness of the intermediate layer is preferably 1p11 or less.

In addition, the azo pigment represented by the general formula [I] is particularly
It effectively acts as a charge-generating material for the laminated photoreceptor as described above.

[Example] Next, specific examples of the present invention will be described, and comparative examples will be given to clarify that the photoreceptor according to the example of the present invention is excellent.

Synthesis Example R in the above general formula [I] is a cyano group, R1
A case in which an azo pigment in which ', R, and l are hydrogen and the coupler component is represented by the chemical formula [11] is synthesized will be specifically described.

Note that other azo pigments represented by the general formula [I] can also be synthesized in substantially the same manner.

Here, in this synthesis example, a compound represented by the following chemical formula (a) was used.

3.0 g (0.01 mol) of the above compound (a) was dispersed in 100 mff of 18N hydrochloric acid, and this dispersion was cooled to a temperature of 5°C with stirring, and 1.4 g (0.01 mol) of the above compound (a) was added to
Add dropwise an aqueous solution of g dissolved in 20 mQ of water,
After the dropwise addition was completed, stirring was continued for an additional hour under cooling. Thereafter, this was filtered, and 50 l of hydrofluoroboric acid was added to the obtained filtrate, and the formed crystals were collected by filtration to obtain a diazonium salt, tetrafluoroborate.

Then, as above, the obtained t; diazonium salt 5°09
(0.01 mol) was dissolved in 300 ma+ of dimethyl sulfoxide along with 6.31 g (0.24 mol) of the coupling agent shown in the chemical formula [11]. Then, a solution of 5 g of sodium acetate dissolved in 30 mm of water was added dropwise at room temperature over about 30 minutes. After the addition was completed, the mixture was stirred for another 3 hours at room temperature, and the precipitated crystals were filtered. I took it.

Then, the obtained crude crystals were dispersed in deionized water IQ and stirred at room temperature for 3 hours, and then the crystals were filtered again, further dispersed in DMF IQ, and stirred at room temperature for 3 hours. Filter the crystals again and disperse them in DMF IQ.
After stirring at room temperature for 3 hours, the crystals were filtered again. D
The MF wash was repeated two more times. Thereafter, the crystals were washed with water and dried to obtain bisazo pigment 6.09 (yield 70.8%).

The bisazo pigment thus obtained was a reddish-purple crystal.

In addition, elemental analysis of this bisazo pigment was performed, and the measured values and calculated values of each element were compared. The results were as shown in Table 1 below.

Table 1 Next, specific examples in which photoreceptors were produced using each azo pigment obtained as described above will be described.

Example 1 In this example, as an azo compound represented by the general formula [rl, the R1 and R1 components are each a cyano group, R1'' and R2'' are each hydrogen, and the coupler components Cp+ and Cpz are A compound represented by chemical formula [2] was used.

Then, 0.45 parts by weight of this azo compound and 0.45 parts by weight of polyester resin (Vylon 200, manufactured by Toyobo Co., Ltd.) were dispersed together with 50 parts by weight of cyclohexanone using a sand glider. 100μm
The charge generation layer was applied onto aluminized mylar using a film applicator and dried to form a charge generation layer having a thickness of 0.3 g/m'.

Next, on the charge generation layer obtained in this way, l,
7 parts by weight of l-bis(p-diethylaminophenyl)-4,4-diphenyl-1,3-butadiene and 7 parts by weight of polycarbonate resin (K-1300: manufactured by Ondai Kasei Co., Ltd.) were mixed with 50 parts by weight of 1,4-dioxane. A solution dissolved in parts by weight was coated and dried to form a 20 μm thick electrotransport layer.

In this way, in this example, a functionally separated laminated photoreceptor having a photosensitive layer consisting of two layers, a charge generation layer containing an azo compound as described above and a charge transport layer, was obtained.

Examples 2 to 10 In these Examples, the azo compounds contained in the charge generation layer include R,, R,, R1', R2''.
The coupler components Cpr and Cpz shown in Table 2 below were used. A laminated photoreceptor having a photosensitive layer consisting of two layers, a charge generation layer and a charge transport layer, was obtained in the same manner as in Example 1 except for the above.

In addition, in this Table 2, the Cp acid components are shown using the numbers of the chemical formulas [1] to [30].

(Hereinafter, blank spaces) Examples If to 15 In these examples, R1, R2, R,', R2' are used as the azo compounds to be contained in the charge generation layer.
The coupler components Cp+ and cp2 shown in Table 3 below are used, and the charge transport material used in the charge transport layer is 1.1-bis(p-diethylaminophenyl)-
4,4-ditolyl-1,3-butadiene and an aryl resin (U-polymer: manufactured by Unitika) were used.

Other than these, a laminated photoreceptor having a photosensitive layer consisting of two layers, a charge generation layer and a charge transport layer, was obtained in the same manner as in Example I above.

Note that the Cp acid component is shown using the numbers from chemical formula [11 to [301].

(Hereinafter, blank space) Comparative Example 1 In this comparative example, a charge-generating material shown in the chemical formula (b) below was used, and the charge-generating layer was formed in the same manner as in Example 1 except for the following: A laminated photoreceptor having a photosensitive layer consisting of two layers, ie, a chamber transport layer and a chamber transport layer, was obtained.

In this comparative example, the charge-generating material shown in chemical formula (d) below was used, and other than that,
In the same manner as in Example 1, a laminated photoreceptor having a photosensitive layer consisting of two layers, a charge generation layer and a charge transport layer, was obtained.

Comparative Example 2 In this comparative example, a charge generating material represented by the chemical formula (c) below was used, and the charge generating layer and charge transport layer were otherwise treated in the same manner as in Example 1. A laminated photoreceptor having a photosensitive layer consisting of two layers was obtained.

Comparative Example 4 In this comparative example, a charge generating material represented by the chemical formula (e) below was used, and the charge generating layer and charge transport layer were otherwise treated in the same manner as in Example 1. A laminated photoreceptor having a photosensitive layer consisting of two layers was obtained.

Comparative Example 3 In order to compare the sensitivities of the photoreceptors of Examples 1 to 15 and Comparative Examples 1 to 4 produced as described above, the half-decrease exposure amount E+/ of each photoreceptor was measured. In addition, in measuring the half-life exposure amount E1/2, each of the above-mentioned photoreceptors was first charged by -6.5 KV corona discharge in a dark place, and then these photoreceptors were exposed to white light with an illuminance of 5 lux. , the exposure amount (lux-sec) required for the surface potential to attenuate to half of the initial surface potential was measured.

The measurement results are as shown in Table 4 below.

Table 4 Effects of the Invention The photoreceptor containing the bisazo pigment represented by the general formula [1] of the present invention has excellent electrostatic properties, particularly sensitivity.

[Brief explanation of the drawing]

1 to 5 are schematic diagrams of photoreceptors according to the present invention, and FIGS. 1, 4, and 5 show dispersion type photoreceptors in which a photosensitive layer is laminated on a conductive support. Figures 2 and 3 show the structure of
The figure shows the structure of a functionally separated photoreceptor in which a charge generation layer and a charge transport layer are laminated on a conductive support. l... Conductive support, 2... Charge transport material, 3
... Photoconductive material, 4... Photosensitive layer, 5... Charge transport layer, 6... Charge generation layer, 7... Surface protective layer, 8... Intermediate layer.

Claims (1)

[Claims] 1. A photoreceptor characterized by having a photosensitive layer containing an azo pigment represented by the following general formula [I] on a conductive support; ▲Includes mathematical formulas, chemical formulas, tables, etc. ▼[I] [In the formula, R_1, R_2, R_1', R_2' are hydrogen,
Indicates an alkyl group, alkoxyl group, halogen atom, cyano group, alkoxycarbonyl group; Cp_1, Cp_2
represents a coupler residue having a phenolic OH group and may be different. ]