JP2615805B2 - Photoconductor - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a photoreceptor used for electrophotography and the like, and more particularly to a photoreceptor having a photosensitive layer containing a novel azo pigment.

[Prior art and its problems] Conventionally, in a photoreceptor used for electrophotography and the like, inorganic photoconductive materials such as selenium, cadmium sulfide, and zinc oxide are known as materials constituting a photosensitive layer.

These inorganic photoconductive materials have a number of advantages, for example, less charge dissipation in dark places, or the ability to quickly dissipate charge by light irradiation, but have various disadvantages. . For example, selenium-based photoreceptors require difficult handling due to difficult manufacturing conditions, high manufacturing costs, and are susceptible to heat and mechanical shock.
In addition, in the case of a zinc oxide photoreceptor or a cadmium sulfide photoreceptor, stable sensitivity cannot be obtained in a humid environment, and a dye added as a sensitizer causes charge deterioration due to corona charging and photobleaching due to exposure. Therefore, there is a disadvantage that stable characteristics cannot be provided for a long period of time.

On the other hand, the use of various organic photoconductive polymers including polyvinyl carbazole as a material for forming the photosensitive layer was also studied. However, these organic photoconductive polymers are superior to the inorganic photoconductive materials described above in terms of film formability and lightness, but still have sufficient sensitivity,
It was inferior to inorganic photoconductive materials in terms of durability and stability due to environmental changes.

In recent years, various research and development have been carried out to solve the drawbacks and problems of these photoconductors, and the charge generation function and the charge transport function of the photoconductive function are shared by different substances. Laminated or distributed type function-separated photoconductors have been developed.

Such a function-separated type photoreceptor has a wide selection range of various substances, and has charging characteristics, sensitivity, residual potential, repetition characteristics,
With regard to electrophotographic characteristics such as printing durability, it is possible to combine the best substances, thereby providing a high-performance photoreceptor. Further, since it can be produced by coating, extremely high productivity and an inexpensive photoreceptor can be provided, and the photosensitive wavelength range can be freely controlled by appropriately selecting the charge generating material. For example, as the charge generation material, organic pigments and dyes such as phthalocyanine pigments, cyanine pigments, polycyclic quinone pigments, perylene pigments, perinone pigments, indigo dyes, thioindigo dyes, squalium pigments, and selenium, selenium / arsenic, selenium / tellurium ,
Inorganic materials such as cadmium sulfide, zinc oxide, and amorphous silicon can be used.

However, even with such a function-separated type photoreceptor, one that still satisfies the general electrostatic characteristics is not easily obtained, and the sensitivity is still not sufficient. In general, an excellent photoconductor has been desired.

[Problem to be Solved by the Invention] The present invention has been made in view of the above circumstances,
It is an object of the present invention to provide a photoreceptor excellent in overall electrostatic characteristics and particularly excellent in sensitivity.

[Means for Solving the Problems] In the photoreceptor according to the present invention, a photosensitive layer containing an azo pigment represented by the following general formula [I] is provided on a conductive support.

[Wherein, R ₁ and R ₂ represent hydrogen, an alkyl group, an alkoxyl group, a halogen atom, or a cyano group. Cp indicates a coupler residue having a phenolic OH group. Here, the azo pigment represented by the general formula [I] of the present invention can be easily synthesized by a usual method.

That is, the following general formula [XII] [Wherein R ₁ and R ₂ have the same meanings as in the above [I]]. The diamino compound represented by the formula [II] is diazotized using sodium nitrite-hydrochloric acid, and the following general formula [II] ] - [either by suitable coupler component coupling represented by XI], or a diamino compound is diazotized, followed after isolation in the form of a salt by adding an acid such as HBF _4, by performing the coupling reaction Can be synthesized by The coupling is usually carried out in a water and / or an organic solvent such as N, N-dimethylformamide at a reaction temperature of 30 to 25 ° C. for 1 hour to 10 hours in accordance with a known method.

[In the formula, X is oxygen, sulfur, a nitrogen atom which may have a substituent, Y is a divalent group of an aromatic hydrocarbon or a divalent group which forms a heterocycle together with a nitrogen atom. And Z are residues which are condensed with a benzene ring to form a polycyclic conjugated ring or a heterocyclic ring. R ₃ , R ₄ , R ₆ , R ₇ , R ₁₀ , R ₁₁ , R ₁₂ , R ₁₃ are hydrogen,
Or an alkyl group, an aralkyl group, an aryl group, or a heterocyclic group which may have a substituent, and each of which may form a ring together. R ₅ and R ₁₄ each represent an optionally substituted alkyl group, aralkyl group, aryl group or heterocyclic group. R ₈ and R ₉ each represent a hydrogen atom, a halogen atom, an alkyl group which may have a substituent, an aralkyl group, an acyl group, an alkoxycarbonyl group, an aryl group, a condensed polycyclic group or a heterocyclic group. R ₁₅ , R ₁₆ and R ₁₇ , R _{18 each} represent hydrogen, a halogen atom, an alkyl group, a nitro group, a substituted sulfone group, an N-optionally substituted carbomoyl group or a sulfamoyl group, or an optionally substituted C-acylamino A phthalimidyl group; R ₁₅ , R ₁₆
And R ₁₇ and R ₁₈ may together form a ring. In particular, the above general formulas [II], [IV], [VII], [VII
In the coupler components of [I] and [IX], R ₃ , R ₄ , R ₁₀ , R
₁₂ is hydrogen and R ₄ , R ₇ , R ₁₁ , R ₁₃ , R ₁₄ are of the following general formula: [Wherein, R ₁₉ is a substituent selected from a halogen, nitro, cyano, and trifluoromethyl group].

In addition, specific examples of the coupler component used in the present invention include those having the following chemical formulas [1] to [30], but are not particularly limited thereto.

Further, the diamino compound represented by the general formula [XII] can be prepared by a known method.

For example, first, as shown in the following reaction formula, the general formula [XI
The dinitro compound represented by the general formula [XV] is synthesized by condensing the dinitrofluorenone represented by the formula [II] and bis (trimethylsilyl) carbodiimide [XIV] using titanium tetrachloride as a catalyst.

The dinitro compound [XV] is reduced by a known method using zinc-calcium chloride, tin chloride-hydrochloric acid, etc., to obtain the diamino compound represented by the general formula [XII].

In the photoreceptor according to the present invention, when forming the photosensitive layer on the conductive support, one or two or more azo pigments represented by the general formula [I] produced as described above are formed on the photosensitive layer. It was made to contain.

As described above, when the photosensitive layer contains one or more azo pigments represented by the general formula [I], the azo pigment acts as a photoconductive substance, and absorbs light to form charge carriers with extremely high efficiency. Occurs, and the sensitivity of the photoreceptor is improved. Although the generated charge carriers can be transported using the azo pigment as a medium, transporting the charge transport material as a medium is more effective.

Here, as the conductive support used for the photoreceptor, a foil or plate of a metal or alloy such as copper, aluminum, silver, iron, nickel, or the like in the form of a sheet or a drum, or a metal such as a plastic Vacuum deposited on film, electroless plating, etc., or a layer of conductive compound such as conductive polymer, indium oxide, tin oxide, etc. is also formed on a support such as paper or plastic film by coating or vapor deposition Can be used.

Although various types of photoconductors are known, the photoconductor of the present invention may be any of those photoconductors.

For example, as shown in FIG. 1, a photoconductive material (2) and a charge transport material (3) are compounded together with a binder on a conductive support (1) as described above, and a photosensitive layer ( The photosensitive layer formed on the conductive support (1) as shown in FIG. 2 or a single-layer type photosensitive body on which the photosensitive layer (4) is formed is a charge generating layer containing a photoconductive material (2). (5) and a charge-transporting layer (6) containing a charge-transporting material (3) are sequentially laminated, and as shown in FIG.
The photosensitive layer formed on the conductive support (1) comprises a charge transport layer (6) containing a charge transport material (3) and a photoconductive material (2), contrary to the case of FIG. It may be a function-separated type photoconductor in which the charge generation layer (5) is sequentially laminated.

Further, as shown in FIG. 4, a photosensitive layer (4) having a surface protective layer (7) provided on the surface thereof, or as shown in FIG.
An intermediate layer (8) may be provided between the conductive support (1) and the photosensitive layer (4). When an intermediate layer is provided between the conductive support and the photosensitive layer as shown in FIG. 5, the adhesiveness and coatability between the conductive support and the photosensitive layer can be improved, It is possible to improve the protection of the conductive support and the injection of charges from the conductive support into the photosensitive layer. Further, such a surface protective layer and an intermediate layer can be provided on the function-separated type photoconductor.

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

In this case, the fine particles of the azo pigment represented by the general formula [I] are dispersed in a resin solution or a solution in which a charge transport compound and a resin are dissolved, and the resultant is coated on a conductive support. Allow to dry. At this time, the thickness of the photosensitive layer is 3 to 30 μm, preferably 5 to 20 μm. If the amount of the azo pigment used is too small, the sensitivity is poor, and if the amount is too large, the chargeability is deteriorated and the mechanical strength of the photosensitive layer is reduced. The amount is 0.01 to 2 parts by weight, preferably 0.2 to 1.2 parts by weight based on parts by weight. When a charge transporting material that can be used as a binder itself, such as polyvinyl carbazole, is used, the amount of the azo pigment added is 0.
It is preferable that the amount be from 01 to 0.5 parts by weight.

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

In this case, the azo pigment is vacuum-deposited on a conductive support, or is dissolved in a solvent such as an amine and applied.
Alternatively, a coating solution in which the azo pigment is dispersed in an appropriate solvent or a solution in which a binder resin is dissolved as necessary is coated on a conductive support and dried to generate a charge on the conductive support. Form a layer. In this case, the thickness of the charge generation layer is set to 4 μm or less, preferably 2 μm or less.

Then, a solution containing a charge transport material and a binder is applied on 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 set to 3 to 50 μm, preferably 5 to 30 μm. The charge transporting material is used in an amount of 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. When the charge transporting material is a polymer charge transporting material that can be used as a binder itself, another binder resin may not be used.

Here, the binder resin used in the manufacture of each photoconductor as described above is electrically insulating and uses a thermoplastic resin, a thermosetting resin, a photocurable resin, a photoconductive resin, or the like known per se. it can. Suitable binder resins are not particularly limited to these, but include, for example, saturated polyester resins, polyamide resins, acrylic resins,
Thermoplastic agents such as ethylene-vinyl acetate copolymer, ion-crosslinked olefin copolymer (ionomer), styrene-butadiene block photopolymer, polycarbonate, vinyl chloride-vinyl acetate copolymer, cellulose ester, polyimide, and styrene resin; Epoxy resin, urethane resin, silicone resin, phenol resin, melamine resin,
Examples include thermosetting resins such as xylene resin, alkyd resin, and thermosetting acrylic resin, photocurable resins, and photoconductive resins such as polyvinylcarbazole, polyvinylpyrene, polyvinylanthracene, and polyvinylpyrrole. These binder resins can be used alone or in combination, and it is desirable that their electrical insulating properties have a volume resistivity of 1 × 10 ¹² Ω · cm or more when measured alone.

In the photoreceptor of the present invention, a plasticizer such as halogenated paraffin, polychlorinated biphenyl, dimethylnaphthalene, dibutyl phthalate, 0-terphenyl, chloranil, tetracyanoethylene, 2, 4,7-trinitrofluorenone,
Electron-withdrawing sensitizers such as 5,6-dicyanobenzoquinone, tetracyanoquinodimethane, tetrachlorophthalic anhydride, 3,5-dinitrobenzoic acid, methyl violet, rhodamine B, cyanine dyes, pyrylium salts, thiapyrylium salts, etc. May be used.

Further, as the charge transporting material used in the above photoreceptor, a hydrazone compound, a pyrazoline compound,
Various compounds such as styryl compounds, triphenylmethane compounds, oxadiazole compounds, carbazole compounds, stilbene compounds, enamine compounds, oxazole compounds, triphenylamine 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) resorcinol, 2-p-anisoleaminofluorene, p-diethylaminoazobenzene, cadion, N, N-dimethyl-p
-Phenylazoaniline, p- (dimethylamino) stilbene, 1,4-bis (2-methylstyryl) benzene,
9- (4-diethylaminostyryl) anthracene, 2,
5-bis (4-diethylaminophenyl) -1,3,5-oxadiazole, 1-phenyl-3- (p-diethylaminostyryl) -5- (p-diethylaminophenyl) pyrazoline, 1-phenyl-3-phenyl -5-pyrazolo, 2- (m-naphthyl) -3-phenyloxazole, 2- (p-diethylaminostyryl) -6-diethylaminobenzoxazole, 2- (p-diethylaminostyryl) -6-diethylaminobenzothiazole,
Bis (4-diethylamino-2-methylphenyl) phenylmethane, 1,1-bis (4-N, N-diethylamino-2
-Ethylphenyl) heptane, N, N-diphenylhydrazino-3-methylidene-10-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-N
-Methyl-N-phenylhydrazone, p-diethylaminobenzaldehyde-N-α-naphthyl-N-phenylhydrazone, p-diethylaminobenzaldehyde-3
-Methylbenzthiazolinone-2-hydrazone, 2-methyl-4-N, N-diphenylamino-β-phenylstilbene, α-phenyl-4-N, N-diphenylaminostilbene, 1,1-bis (P -Diethylaminophenyl)
A charge transport material such as -4,4-diphenyl-1,3-butadiene is used alone or in combination of two or more.

When a surface protective layer is provided as shown in FIG. 4, the material may be a polymer such as an acrylic resin, a polyaryl resin, a polycarbonate resin, a urethane resin, or a low-resistance compound such as tin oxide or indium oxide. Dispersed ones are suitable, and an organic plasma polymerized film can also be used. The organic plasma polymerized film should contain oxygen, nitrogen, halogen, Group III and Group V atoms of the periodic table as necessary. Is also possible. The thickness of the surface protective layer is desirably 5 μm or less.

When an intermediate layer is provided as shown in FIG. 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. A dispersion material, a vapor-deposited film of aluminum oxide, zinc oxide, silicon oxide, or the like is suitable. In this case, the thickness of the intermediate layer is desirably 1 μm or less.

In addition, the azo pigment represented by the general formula [I] particularly effectively functions as a charge generation material of the above-mentioned laminated photoreceptor.

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

First, the case of synthesizing the azo pigment represented by the general formula [I] used in the present invention will be specifically described.

Synthesis Example In this synthesis example, a case will be described in which R ₁ and R ₂ in the general formula [I] are hydrogen, and an azo pigment having a coupler component Cp represented by the chemical formula [1] is synthesized.

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

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

Then, 2.34 g (0.01 mol) of the compound (a) was dispersed in 100 ml of 2N hydrochloric acid, and the dispersion was cooled to 5 ° C. while stirring, and 1.4 g of sodium nitrite was dissolved in 20 ml of water. The resulting aqueous solution was added dropwise, and after completion of the addition, stirring was further performed for 1 hour under cooling. Thereafter, this was filtered, 10 g of borofluoric acid was added to the obtained filtrate, and the generated crystal was collected by filtration to obtain N-cyanofluorenimine tetrafluoroborate.

Next, 3.16 g of the diazonium salt obtained as described above
(0.01 mol) was dissolved in 300 ml of N-methylpyrrolidone together with 6.98 g of the coupling agent represented by the chemical formula [1]. Then, a solution prepared by dissolving 5 g of sodium acetate in 100 ml of water was added dropwise at 10 to 20 ° C. in about 30 minutes, and after completion of the addition, the mixture was further stirred at room temperature for 3 hours. Was collected by filtration.

Then, the obtained crude crystal was dispersed in DMF11, and the mixture was stirred at room temperature for 3 hours. Then, the crystal was collected by filtration again, and this operation was further repeated twice. Thereafter, the crystals were washed with water and dried to obtain 6.7 g of a bisazo pigment (yield: 88.9%).

The bisazo pigment thus obtained was a purple crystal.

The bisazo pigment was subjected to elemental analysis, and the measured value and calculated value of each element were compared. This result is described in the first section below.
As shown in the table.

Next, specific examples in which a photoreceptor is manufactured using each of the azo pigments obtained as described above will be described.

Example 1 In this example, as an azo compound represented by the general formula [I], the R ₁ and R ₂ components are each hydrogen and the coupler component Cp is composed of a compound represented by the aforementioned chemical formula [2]. Was used.

Then, 0.45 parts by weight of the azo compound and 0.45 parts by weight of a polyester resin (byron 200 manufactured by Toyobo Co., Ltd.)
The dispersion was dispersed with a sand glider together with 50 parts by weight of cyclohexanone, and this dispersion was applied to a 100 μm-thick aluminized mylar using a film applicator, and dried to form a charge generation layer having a thickness of 0.3 g / m ^2. Formed.

Next, on the charge generation layer thus obtained,
7 parts by weight of 1,1-bis (p-diethylaminophenyl) -4,4-diphenyl-1,3-butadiene and 7 parts by weight of a polycarbonate resin (manufactured by K-1300 Teijin Chemicals Ltd.) are mixed with 1,4
-A solution dissolved in 50 parts by weight of dioxane was applied and dried to form a charge transport layer having a thickness of 20 µm.

Thus, in this example, a function-separated laminated photoreceptor having a photosensitive layer composed of two layers, the charge generation layer containing the azo compound as described above and the charge transport layer, was obtained.

Examples 2 to 10 In these examples, as the azo compound contained in the charge generation layer, R ₁ , R ₂ and a coupler component C were used.
Those having p as shown in Table 2 below were used. Otherwise, in the same manner as in Example 1 above, a laminated photoreceptor having a photosensitive layer composed of two layers, a charge generation layer and a charge transport layer, was obtained.

In Table ₂ , the numbers shown before the elements R ₁ and R ₂ indicate the positions in the fluorene ring, and the Cp component is represented by using the numbers of the chemical formulas [1] to [30]. Indicated.

Examples 11 to 15 In these examples, as the azo compound to be contained in the charge generation layer, its R ₁ , R ₂ and coupler component C
p is used as shown in Table 3 below, and 1,1-bis (p-diethylaminophenyl) -4,4-ditolyl-1,3-diene and an aryl resin are used as a charge transport material for the charge transport layer. (U-Polymer Unitika Ltd.) was used.

Except for these, in the same manner as in Example 1 above, a laminated photoreceptor having a photosensitive layer composed of two layers, a charge generation layer and a charge transport layer, was obtained.

Also in Table 3, the numbers before the elements R ₁ and R ₂ indicate the positions in the fluorene ring, and the Cp components are indicated using the numbers of the chemical formulas [1] to [30]. .

Comparative Example 1 In this comparative example, a charge-generating material represented by the following chemical formula (b) was used.
In the same manner as in Example 1, a laminated photoreceptor having a photosensitive layer composed 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 was used as shown in the following chemical formula (c). Otherwise, the charge generating layer and the charge transporting were performed in the same manner as in Example 1. Thus, a laminated photoreceptor having a photosensitive layer composed of two layers was obtained.

Comparative Example 3 In this comparative example, a charge generating material and a charge transporting layer were used in the same manner as in Example 1 except that a charge generating material represented by the following chemical formula (d) was used. To obtain a laminated photoreceptor having a two-layer photosensitive layer.

COMPARATIVE EXAMPLE 4 In this comparative example, a charge generating material represented by the following chemical formula (e) was used, and otherwise, the charge generating layer and the charge transport were performed in the same manner as in Example 1. Thus, a laminated photoreceptor having a photosensitive layer composed of two layers was obtained.

Then, in order to compare the sensitivities of the photoconductors of Examples 1 to 15 and Comparative Examples 1 to 4 manufactured as described above, the half-exposure amount E _1/2 of each photoconductor was measured. In addition,
In the measurement of the half-life exposure amount E1 _{/ 2} , each of the above-mentioned photoconductors was first charged in a dark place by corona discharge of -6.5 KV, and then these photoconductors were exposed to white light having an illuminance of 5 lux to obtain a surface potential. The amount of exposure (lux · sec) required for decay to half of the initial surface potential was measured.

 The measurement results are as shown in Table 4 below.

As described above, the photoreceptors according to the examples of the present invention have remarkably low half-exposure amounts E _{1/2 as} compared with the respective photoreceptors of the comparative example, and are excellent in electrophotographic characteristics, particularly in terms of sensitivity. I was

[Effects of the Invention] As described above in detail, in the photoreceptor according to the present invention, as a material to be contained in the photosensitive layer, a novel azo pigment represented by the general formula [I] is contained. It has become possible to obtain a photoreceptor excellent in overall electrophotographic properties, particularly in sensitivity and repetition stability.

[Brief description of the drawings]

1 to 5 are schematic cross-sectional views of a photoreceptor according to the present invention. FIGS. 1, 4 and 5 show a photoconductor on a conductive support.
2 and 3 show a function-separated type photoconductor in which a charge generation layer and a charge transport layer are laminated on a conductive support. Is shown. (1) ... conductive support, (2) ... photoconductive material (3) ... charge transport material, (4) ... photosensitive layer (5) ... charge generation layer, (6) ... charge Transport layer (7): Surface protection layer, (8): Intermediate layer

Claims (1)

(57) [Claims] 1. A photoreceptor comprising a photosensitive layer containing an azo pigment represented by the following general formula [I] on a conductive support. [Wherein, R ₁ and R ₂ represent hydrogen, an alkyl group, an alkoxyl group, a halogen atom, or a cyano group. Cp indicates a coupler residue having a phenolic OH group. ]