JP2001296674A - Organic photoconductive material and electrophotographic photoreceptor using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily produce electrographic photoreceptor, having high sensitivity and to easily and stably produce various material of an electrophotographic photoreceptor, etc., by greatly enhancing the coating stability of a dispersion. SOLUTION: An asymmetric azo compound of general formula [I] is mixed with 0.1-15 wt.% symmetric azo compound of general formula [III] or [IV] to obtain the objective organic photoconductive material.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an organic photoconductive substance and an electrophotographic photosensitive member using the same.

[0002]

2. Description of the Related Art In recent years, the use of electrophotography has been extended to fields in which photographic technology was conventionally used, such as printing plates, slide films, microfilms, etc., in addition to the field of copying machines. Also, application to a high-speed printer using a CRT as a light source is being studied. Recently, the use of a photoconductive material for applications other than electrophotography, for example, an application for an electrostatic recording element, a sensor material, and the like has begun to be studied. Accordingly, demands for photoconductive materials and electrophotographic photoreceptors using the same are becoming higher and wider.

As an electrophotographic photoreceptor using a photoconductive material as a photosensitive material, inorganic photoconductive materials such as selenium compounds, cadmium sulfide, and zinc oxide have been conventionally used. However, these inorganic compounds generally have poor processability and are highly toxic, and many materials have problems in disposal.

[0004]

In order to improve the disadvantages of such inorganic materials, research on electrophotographic photoreceptors using an organic compound as a photoconductive substance has been widely conducted, and non-toxic photoreceptors have been developed. Many organic photoconductive materials have been put to practical use, taking advantage of ease of processing, light weight, flexibility and the like, and also because of easy molecular design.

As the organic photoconductive substance used for these applications, azo compounds, phthalocyanine compounds, azulenium salts, squarylium salts and other polycyclic compounds are known. Among them, azo compounds are relatively easy to synthesize and have advantages such as being able to have many structural variations. In recent years, many promising azo compounds have been proposed. .

The characteristics required for the electrophotographic photoreceptor include, in addition to the electrical properties such as chargeability, sensitivity, and durability, the dispersibility in preparing a dispersion for coating on a conductive substrate, or the dispersion. And the like. However, at present, an organic photoconductive material satisfying all these requirements has not been obtained. In recent years, the asymmetric azo compounds reported in Japanese Patent Application No. 5-163206 also have excellent electrophotographic properties, but leave some problems in the stability of the obtained paints, To meet the wide range of demands.

Various dispersion stabilizers (eg, sorbitan fatty acid esters, alkylimidazolines, alkylbenzenesulfonic acids) for improving the stability of the dispersion liquid
May be considered, but the addition of these dispersion stabilizers inevitably lowers the charge generation efficiency of the charge generating agent used, which is not preferred. There is also a method using a strong basic solvent such as n-butylamine or ethylenediamine as a solvent, but it is not practical in view of the toxicity.

[0008]

The present inventors have studied to improve the organic conductive substance disclosed in Japanese Patent Application No. 5-163206 and found that the following azo compounds represented by the following general formula [1] are included. It has been found that by incorporating 0.1 to 15% by weight of a symmetric azo compound represented by the general formula [3] or the following general formula [4], the stability of the coating material is significantly improved.
The present invention has been reached.

That is, the present invention provides asymmetric azo compounds represented by the following general formula [3] or [4] among asymmetric azo compounds represented by the following general formula [1]: 0.1 to 15% by weight of an organic photoconductive substance, an electrophotographic photoreceptor using the substance,
And an information recording device. (Where A is a coupler residue having a phenolic OH group, B is a coupler residue different from A and represented by the following general formula [2]. Y is an alkyl group, an alkoxy group, a halogen atom, It represents an integer group of l = 0-4 selected from a nitro group and a halogenated alkyl group.) (Wherein X is an atomic group necessary for forming a substituted / unsubstituted aromatic hydrocarbon ring or substituted / unsubstituted aromatic heterocyclic ring by condensing with a benzene ring, Z is an alkyl group, an alkoxy group, a halogen M selected from an atom and a halogenated alkyl group
R is an integer group of 0 to 4, and R represents an integer group of n = 1 or 2 selected from a substituted / unsubstituted aromatic hydrocarbon ring group and a substituted / unsubstituted aromatic heterocyclic group. )

[0010] (However, in the general formula [3] or [4], A, B,
Y and 1 are the same as those shown in the general formula [1]. )

According to the present invention, not only high sensitivity, but also excellent electrophotographic characteristics such as charging characteristics, potential holding power and residual potential, good film characteristics, little deterioration due to repeated use, heat and temperature Organic photoconductive that can be used for sensor materials or electrostatic recording elements in addition to electrophotographic photoreceptors that can exhibit stable performance without changing various properties against light Sexual substances can be provided.

[0012]

Next, the present invention will be described in more detail with reference to preferred embodiments. Specific examples of the azo-based compound useful in the present invention represented by the general formula [1] include, for example, those having the following structural formulas, which do not limit the azo-based compound of the present invention. Absent. In the following specific examples, the left coupler residue in the structural formula represents A in the general formula [1], and the right coupler residue represents B in the general formula [1].

[0013]

[0014]

[0015]

[0016]

The above-mentioned azo compound is disclosed in JP-A-6-348.
No. 047 can be synthesized by a known method. In the present invention, there are two types of symmetric azo compounds to be mixed with the asymmetric azo compound represented by the general formula [1], those represented by the general formula [3] and those represented by the general formula [4]. , Or both of them can be mixed at the same time to obtain a predetermined effect. In the present invention, examples of the symmetric azo pigments used by being mixed with the above-mentioned asymmetric azo pigments will be described below with respect to the case of the exemplified compounds (1), (3) and (5).

Examples of symmetric azo compounds

[0019]

[0020]

In order to mix a symmetric azo compound,
There are two methods, a method of adding after the synthesis of the asymmetric azo compound, and a method of mixing and coupling two types of couplers at a predetermined ratio during the synthesis of the asymmetric azo compound, either of which may be used. .

In the electrophotographic photoreceptor of the present invention, another charge generating substance may be used in combination with the azo compound of the present invention as a charge generating substance. Examples of the charge generating substance that can be used in combination include a perylene compound, a perinone compound, a polycyclic compound, an anthraquinone compound, a dioxazine compound, an azurenium salt compound, a squarylium salt compound, and a pyrrolopyrrole compound.

In order to form the photosensitive layer of the electrophotographic photosensitive member according to the present invention, a resin binder dispersion of the above-mentioned azo compound is coated on a known conductive support and then dried to form a film. . Any binder can be used as long as it has a film-forming property, but a polymer compound having a high dielectric constant and good electric insulation is particularly desirable. Examples of the polymer compound include methacrylic resin, acrylic resin, polyester resin, polyvinyl chloride resin, polycarbonate resin,
Polyvinyl formal resin, polyvinyl butyral resin, polystyrene resin, polyvinyl acetate resin, polyvinyl carbazole resin, polyvinyl alcohol resin, melamine resin, alkyd resin, polyamide resin, polyurethane resin, styrene-maleic anhydride copolymer, vinyl chloride-vinyl acetate Copolymers, styrene-butadiene copolymers and the like can be mentioned.

The formation of the photosensitive layer is carried out by applying the above-mentioned dispersion onto a conductive support using a bar coater, applicator, doctor blade, roll coater, dipping, spray coater, spin coater or the like. be able to.

The structure of the electrophotographic photoreceptor of the present invention includes:
Both a single-layer type and a laminated type can be used. Further, in addition to the above-mentioned layers, an intermediate layer may be provided on the conductive support, or a surface protective layer may be provided on the uppermost part.

The charge transporting substance which can be used in the electrophotographic photoreceptor of the present invention includes a hydrazone compound,
Examples include tetraarylbutadiene-based compounds, oxazole-based compounds, thiazole-based compounds, oxadiazole-based compounds, oxathiadiazole-based compounds, stilbene-based compounds, pyrazoline-based compounds, triarylamine-based compounds, and benzidine-based compounds. Among these compounds, those having an aromatic ring may have a condensed polycyclic structure at the portion. It is also possible to use a mixture of two or more of these.

The preferred amount of the symmetric azo compound in the organic photoconductive material of the present invention increases the stability of the resin dispersion without impairing the excellent electrical characteristics of the original asymmetric azo compound. Considering the purpose, 0.1 to 15%, more preferably 0.1 to 15% of the total amount of the organic photoconductive substance.
1 to 5%.

Further, in the electrophotographic photoreceptor of the present invention, various additives can be added for the purpose of improving various physical properties. The addition amount is preferably from 0.1 to 20 parts by weight based on 100 parts by weight of the whole organic photoconductive material as the charge generating substance.

It was confirmed that the photoreceptor using the azo compound represented by the general formula [1] of the present invention had excellent electric properties. Further, the electrophotographic photoreceptor of the present invention can be applied not only to a plain paper copying machine but also to the production of an electroplate, a sensor material or a printed circuit board employing an electrophotographic method. Specifically, the following examples will be described.

[0030]

The contents of the present invention will be further described by the following examples.
explain in detail. "%" In the text indicates% by weight. In addition,
Electrophotographic characteristics of the photoreceptor
The measurement was performed using a copying paper test apparatus SP428. Measurement is -5
Charge the photoreceptor surface by performing a corona discharge of kV for 3 seconds.
And leave it in a dark place for 10 seconds, then illuminate it with a halogen lamp.
Irradiation energy required to halve the surface potential
Amount, ie, half-exposure dose (E _1/2) And the surface potential is -50 V
Energy required to become (E₅₀), Seek
I went in a cycle called.

<Example 1> In a 200 ml poly bottle, 990 mg of the above-mentioned exemplified compound (1), 10 mg of a symmetric azo pigment of the general formula [3], 1.0 g of a polyester resin (trade name: Byron 200 manufactured by Toyobo), and cyclohexanone 24
g, methyl ethyl ketone 56 g and glass beads 70 g
Was dispersed by a paint shaker for 60 minutes, and applied on an aluminum substrate by a wire coater so as to have a dry film thickness of 0.5 μm to form a charge generation layer.

On the other hand, a solution prepared by dissolving 10 g of a polycarbonate resin (trade name: Panlite K1300 manufactured by Teijin Chemicals Co., Ltd.) and 10 parts of a hydrazone derivative (trade name: T215 manufactured by Annan Co., Ltd.) in 80 parts of dichloromethane is charged with a wedge bar using the above-mentioned charge generation layer. A charge transport layer was formed thereon by coating so as to have a dry film thickness of 20 μm, thereby producing an electrophotographic photoreceptor.

When the electrophotographic characteristics of the obtained photoreceptor were measured by the above-mentioned method, the initial charging potential was -720 V, the potential holding ratio was 98%, E _1/2 was 1.00 Lux · sec,
E ₅₀ is 3.50Lux · sec residual potential was -5V. The obtained pigment / resin dispersion liquid did not gel even after 60 days from the preparation, and the viscosity of the paint remained unchanged from the initial preparation.

Example 2 A photoconductor was prepared in the same manner as in Example 1, except that 990 mg of the above-mentioned exemplified compound (1) and 10 mg of a symmetric azo pigment of the general formula [4] were used as charge generating substances. When the electrophotographic characteristics of the obtained photoreceptor were measured by the method described above, the initial charging potential was -710.
V, potential holding rate is 97%, E _1/2 is 1.00 Lux · s
ec, E ₅₀ is 3.50 Lux · sec, and the residual potential is −3.
V. In addition, after the obtained pigment / resin dispersion liquid is prepared,
Gelling did not occur even after 60 days, and the viscosity of the paint remained unchanged from that at the time of preparation.

<Example 3> Examples 980 mg of the exemplified compound (1), 10 mg of the symmetric azo pigment of the general formula [3] and 10 mg of the symmetric azo pigment of the general formula [4] were used as the charge generating material. A photosensitive member was prepared in the same manner as in Example 1. When the electrophotographic characteristics of the obtained photoreceptor were measured by the above-described method, the initial charging potential was −720 V, the potential holding ratio was 98%, E _1/2 was 1.05 Lux · sec, and E _50.
Was 3.60 Lux · sec, and the residual potential was −3 V. The obtained pigment / resin dispersion liquid did not gel even after 60 days from the preparation, and the viscosity of the paint remained unchanged from the initial preparation.

<Comparative Example 1> A photoconductor was prepared in the same manner as in Example 1, except that 1.0 g of the exemplified compound (1) was used as a charge generating substance. When the electrophotographic characteristics of the obtained photoreceptor were measured by the above method, the initial charging potential was -73.
0 V, potential holding rate 98%, E _1/2 1.00 Lux
sec, E ₅₀ is 3.45Lux · sec, residual potential -
It was 4V. In addition, the obtained pigment / resin dispersion liquid was remarkably thickened and gelled 10 days after the preparation, and it was difficult to apply the dispersion liquid on a conductive substrate using the dispersion liquid.

<Example 4> [0037] Except that 980 mg of the exemplified compound (3), 10 mg of the general formula [3] type symmetric azo pigment and 10 mg of the general formula [4] type symmetric azo pigment were used as the charge generating material. A photosensitive member was prepared in the same manner as in Example 1. When the electrophotographic characteristics of the obtained photoreceptor were measured by the above-mentioned method, the initial charging potential was −680 V, the potential holding ratio was 97%, E _1/2 was 1.00 Lux · sec, E
₅₀ was 3.70 Lux · sec, and the residual potential was −3 V. The obtained pigment / resin dispersion liquid did not gel even after 60 days from the preparation, and the viscosity of the paint remained unchanged from the initial preparation.

Example 5 980 mg of the exemplified compound (3), 5 mg of the general formula [3] type symmetric azo pigment and 5 mg of the general formula [4] type symmetric azo pigment 1 as the charge generating material
A photoconductor was prepared in the same manner as in Example 1, except that 5 mg was used. When the electrophotographic characteristics of the obtained photoreceptor were measured by the above-mentioned method, the initial charging potential was -670 V, the potential holding ratio was 96%, E _1/2 was 0.95 Lux · sec, and E _50.
Was 3.55 Lux · sec, and the residual potential was −2 V. The obtained pigment / resin dispersion liquid did not gel even after 60 days from the preparation, and the viscosity of the paint remained unchanged from the initial preparation.

Comparative Example 2 A photoconductor was prepared in the same manner as in Example 1, except that 1.0 g of the exemplified compound (3) was used as a charge generating substance. When the electrophotographic characteristics of the obtained photoreceptor were measured by the method described above, the initial charging potential was -6.
90V, 98% potential holding ratio, 0.95 Lux E _1/2
· Sec, E ₅₀ is 3.55Lux · sec, residual potential was -2 V. Incidentally, the pigment / resin dispersion obtained was remarkably thickened and gelled after 15 days from the preparation, and it was difficult to apply the dispersion on a conductive substrate using this dispersion.

Example 6 A photoconductor was prepared by the same way as that of Example 1 except that 990 mg of the above-mentioned exemplified compound (13) and 10 mg of a symmetric azo pigment of the general formula [4] were used as charge generating substances. When the electrophotographic characteristics of the obtained photoreceptor were measured by the method described above, the initial charging potential was -75.
0 V, potential holding ratio is 96%, E _1/2 is 0.90 Lux ·
sec, E _{5 0} is 3.30Lux · sec, the residual potential -
It was 1V. The obtained pigment / resin dispersion liquid did not gel even after 60 days from the preparation, and the viscosity of the paint remained unchanged from the initial preparation.

Example 7 Example 7 was repeated except that 980 mg of the exemplified compound (13), 15 mg of the symmetric azo pigment of the general formula [3] and 5 mg of the symmetric azo pigment of the general formula [4] were used as the charge generating material. A photosensitive member was prepared in the same manner as in Example 1. When the electrophotographic characteristics of the obtained photoreceptor were measured by the above-mentioned method, the initial charging potential was -750 V, the potential holding ratio was 98%, E _1/2 was 0.95 Lux · sec, and E
₅₀ was 3.45 Lux · sec, and the residual potential was −3 V. The obtained pigment / resin dispersion liquid did not gel even after 60 days from the preparation, and the viscosity of the paint remained unchanged from the initial preparation.

Comparative Example 3 A photoconductor was prepared in the same manner as in Example 1, except that 1.0 g of the exemplified compound (13) was used as a charge generating substance. When the electrophotographic characteristics of the obtained photoreceptor were measured by the above method, the initial charging potential was-
760 V, potential holding rate of 98%, E _1/2 of 0.90 Lu
x · sec, E ₅₀ were 3.30 Lux · sec, and the residual potential was −1 V. The resulting pigment / resin dispersion liquid did not gel after 15 days from its preparation, but was significantly thickened, and it was difficult to apply the dispersion liquid on a conductive substrate.

[0043]

As described above, an electrophotographic photosensitive member having high sensitivity can be easily manufactured by using an organic photoconductive substance according to the present invention. Furthermore,
The present invention significantly improves the paint stability of the dispersion, thereby facilitating various materials including electrophotographic photoreceptors,
And it enables stable production.

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Shiro Yamamiya 1-7-6 Nihombashi Bakurocho, Chuo-ku, Tokyo Inside Dainichi Seika Kogyo Co., Ltd. (72) Inventor Tetsuo Fukuda 1-7 Nihonbashi Bakurocho, Chuo-ku, Tokyo No. 6 Inside Dainichi Seika Kogyo Co., Ltd. (72) Inventor Yoshio Abe 1-7-6 Bakumacho, Nihonbashi, Chuo-ku, Tokyo F-term inside Dainichi Seika Kogyo Co., Ltd. 2H068 AA19 AA32 BA44 BA53 FA13

Claims (4)

[Claims] 1. An asymmetric azo compound represented by the following general formula [1], wherein a symmetric azo compound represented by the following general formula [3] or [4] is 0.1 to An organic photoconductive substance characterized by being mixed at 15% by weight. (Where A is a coupler residue having a phenolic OH group, B is a coupler residue different from A and represented by the following general formula [2]. Y is an alkyl group, an alkoxy group, a halogen atom, It represents an integer group of l = 0-4 selected from a nitro group and a halogenated alkyl group.) (Wherein X is an atomic group necessary for forming a substituted / unsubstituted aromatic hydrocarbon ring or substituted / unsubstituted aromatic heterocyclic ring by condensing with a benzene ring, Z is an alkyl group, an alkoxy group, a halogen M selected from an atom and a halogenated alkyl group
R is an integer group of 0 to 4, and R represents an integer group of n = 1 or 2 selected from a substituted / unsubstituted aromatic hydrocarbon ring group and a substituted / unsubstituted aromatic heterocyclic group. ) (However, in the general formula [3] or [4], A, B,
Y and 1 are the same as those shown in the general formula [1]. ) 2. An electrophotographic photosensitive member comprising a photosensitive layer provided on a conductive support, wherein the photosensitive layer contains the organic photoconductive substance according to claim 1. 3. The electrophotograph according to claim 2, wherein the photosensitive layer contains a charge generating substance and a charge transporting substance, and the charge generating substance is the organic photoconductive substance according to claim 1 or 2. Photoconductor. 4. A printing plate material, a sensor material, an electrostatic recording element, a printed circuit board, or an information recording device to which photoconductive properties are applied, wherein the photosensitive member according to claim 2 or 3 is used.