JP2628430B2 - Electrophotographic photoreceptor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel electrophotographic photosensitive member having a photosensitive layer containing a specific azo compound.

[0002]

2. Description of the Related Art In recent years, the use of electrophotography has become widespread not only in the field of copiers but also in the fields of printing plates, slide films, microfilms and the like, where photographic technology has been mainly used. Application to a high-speed printer using a laser or CRT as a light source is being studied. Against this background, quality requirements for electrophotographic photoreceptors have become stricter, and higher performance and diversification have been demanded.

[0003] Photoconductors used in conventional electrophotographic systems mainly include those mainly containing an inorganic conductive material such as amorphous selenium, cadmium sulfide, and zinc oxide. Recently, an electrophotographic photoreceptor using an organic substance has been developed to make up for the various disadvantages caused by the inorganic system, and has been put to practical use.

[0004]

Since the performance of an electrophotographic photosensitive member is largely controlled by a carrier generating function and a carrier transporting function, enhancing these functions is an important issue for quality improvement. However, at present, there is no organic substance-based photoreceptor known so far that sufficiently exhibits the above-mentioned functions.

The present inventors have conducted various studies on organic electrophotographic photoreceptors. As a result, when an azo compound containing an azo group bonded to a specific coupler residue in the molecule is used as a photosensitive layer, It has been confirmed that it has an excellent carrier generation function, exhibits high and stable electrophotographic performance, and has little fluctuation deterioration due to repeated use.

The present invention has been developed on the basis of such knowledge, and an object of the present invention is to provide a novel organic material-based electrophotographic photoreceptor which exhibits high electrophotographic performance, is stable in material, and can withstand repeated use. Is to do.

[0007]

According to the present invention, there is provided an electrophotographic photoreceptor having a photosensitive layer, wherein the photoreceptor has the following general formula: It is characterized by containing an azo compound having at least one azo group bonded to a coupler residue of the formula.

Wherein X is a group of atoms necessary for forming a substituted or unsubstituted aromatic hydrocarbon ring or aromatic heterocyclic ring by condensing with a benzene ring, R ₁ is hydrogen, and R ₂ is substituted -Represents an unsubstituted alkyl group, a substituted or unsubstituted aralkyl group, a substituted or unsubstituted aromatic hydrocarbon ring group or a substituted or unsubstituted aromatic heterocyclic group.

Among the azo compounds used in the present invention, particularly preferred are bisazo compounds represented by the following general formula:
It is a trisazo compound or a tetrakisazo compound.

Embedded image In Formula 2, n represents an integer of 1 to 4, and X, R ₁ , R
₂ is the same as in Chemical formula 1. A is an n-valent group, and (a)
A hydrocarbon group having at least one benzene ring,
(B) a nitrogen-containing hydrocarbon group having at least two benzene rings; and (c) a hydrocarbon group having at least two benzene rings and at least one heterocycle. The benzene ring in the groups (a) and (b) may be fused with another benzene ring to form a condensed ring, and the benzene ring in the group (C) may be one or more other benzene rings or heterocyclic groups. It may be fused with a ring to form a fused ring. Further, the hydrocarbon group, nitrogen-containing hydrocarbon group, benzene ring and heterocycle in the groups (a) to (c)
It can also be substituted by an organic residue such as a halogen atom, an alkyl group, an alkoxy group, an alkylamino group, an arylamino group, an acylamino group, a nitro group, a cyano group or a hydroxy group.

Further, each of the groups (a), (b) and (c) is specifically described as follows. First, examples of the group (a) include the following chemical formulas (3) to (10).

[0010]

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[Formula 10]

The groups (b) include the following chemical formulas (11) to (18).

[0012]

[Formula 11]

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Examples of the group (c) include the following chemical formulas (19) to (26).

[0014]

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Tables 1 to 10 specifically show examples of azo compounds useful for the purpose of the present invention shown in Chemical formula 2. However, the azo compounds targeted by the present invention are not limited to these.

[0016]

[Table 1]

[Table 2]

[Table 3]

[Table 4]

[Table 5]

[Table 6]

[Table 7]

[Table 8]

[Table 9]

[Table 10]

The above-mentioned azo compound can be synthesized by a known method. First, the amine as a starting material is diazotized by a conventional method, and the resulting diazonium salt is coupled with a corresponding coupler in the presence of an alkali, or the diazonium salt of the amine is stabilized in the form of a borofluoride salt or the like. Once, and then easily synthesized by coupling in an appropriate solvent such as N, N-dimethylformamide in the presence of a base.

Next, synthesis methods of typical examples of the azo compound used in the present invention will be described. For example, the compounds in Table 1
The synthesis of (2) is performed as follows. 49.5 parts by weight of 3,3-dichlorobenzidine hydrochloride were dispersed in a hydrochloric acid solution prepared from 200 parts by weight of 35% concentrated hydrochloric acid and 240 parts by weight of water, and the mixture was cooled to 0 ° C. and then 18% by weight of nitrous acid. 145 parts by weight of the aqueous sodium solution is added dropwise for about 15 minutes while maintaining the liquid temperature at 3 ° C. About 30 at the same temperature
A minute amount of insoluble material was removed by filtration by stirring for minutes, and the concentration of the filtrate was 42%.
And 94 parts by weight of borohydrofluoric acid are added, followed by filtration, and the resulting precipitate is filtered off. The precipitate is washed with cold water and dried to yield 65.0 parts by weight (96% yield) of bisdiazonium salt. Then, the coupler component [compound of Table 1] was added to 450 parts by weight of N, N-dimethylformamide.
(1)] is dissolved in 8.4 parts by weight and 3.6 parts by weight of the above bisdiazonium salt. To this, 10 parts by weight of a 15% solution of triethanolamine in N, N-dimethylformamide is added dropwise at room temperature over 15 minutes, followed by stirring at the same temperature for 3 hours. The resulting precipitate was collected by filtration, washed with N, N-dimethylformamide, methanol and water in this order, and dried to obtain 8.7 parts by weight (yield: 85%) of the compound shown in Table 1.
The bisazo compound shown in (1) is obtained.

The physical composition of the electrophotographic photosensitive member according to the present invention may be any of known forms. That is, a carrier generating layer mainly composed of the above-mentioned azo compound as a carrier generating substance and a carrier transporting layer mainly composed of a carrier transporting substance are laminated on a conductive support. This corresponds to a form in which a photosensitive layer dispersed in a substance is provided, or a form in which these are formed via an intermediate layer such as a barrier layer or an adhesive layer. Specific layer forms include, for example, a support / carrier generation layer / carrier transport layer, a support / carrier transport layer / carrier generation layer, a support / carrier transport layer containing a carrier generation substance, a support / intermediate layer / carrier. A generation layer / carrier transport layer, a support / intermediate layer / carrier transport layer / carrier generation layer, a support / intermediate layer / carrier transport layer containing a carrier generation substance, and the like can be given. It should be noted that a thin layer for the purpose of surface protection can be formed on the photosensitive member having such a configuration. Further, the carrier transporting substance includes a substance that transports electrons and a substance that transports holes, and both of them can be used for the electrophotographic photosensitive member of the present invention.

The electrophotographic photoreceptor according to the present invention can be manufactured according to a conventionally known photoconductor manufacturing technique using an organic photoconductive substance. For example, the carrier generation layer forming the photosensitive layer having a two-layer structure is obtained by forming the azo compound into fine particles in an appropriate medium, adding a binder as necessary, and directly or via an intermediate layer on the conductive support. Or on the already formed carrier transport layer and dried. The fine particles in the medium must be dispersed with a particle size of 5 μm or less, preferably 3 μm or less, and optimally 1 μm or less. When a binder is used, there is no particular limitation, and various thermoplastic or thermosetting synthetic resins can be suitably used. In particular, it is hydrophobic and has a high dielectric constant,
It is desirable to apply a high molecular compound that can easily form an electrically insulating film. As will be readily understood, it is preferred that the medium has the ability to dissolve these binder components. The amount of the binder used is set in the range of 0.1 to 5 times the weight of the carrier-derived material. The thickness of the carrier generation layer is in the range of 0.01 to 20 μ, preferably 0.05 to 5 μ.

The carrier transporting layer can be formed by dispersing or dissolving a carrier transporting substance in a suitable medium, coating and drying. At this time, it is preferable to use a binder unless the carrier transporting substance uses a substance that itself plays a role of a binder such as poly-N-vinylcarbazole or polyglycidylcarbazole. As the binder, the same components as those of the carrier generation layer are used, and the amount of the binder is suitably in the range of 0.2 to 5 times the weight of the carrier transporting substance. The thickness of the carrier transport layer is in the range of 1 to 100 μm, preferably 5 to 100 μm.
50μ.

On the other hand, in order to form a dispersion type carrier generation-carrier transport layer, a carrier transport substance may be dissolved or dispersed in the above-described dispersion for forming a carrier generation layer and applied onto a conductive support. . The carrier transporting material can be arbitrarily selected, but it is generally preferable to add a binder except for the case where the carrier itself functions as a binder as described above. When an intermediate layer is provided between the photosensitive layer and the laminated or dispersed type, the intermediate layer is formed of one or a mixture of two or more of a carrier-generating substance, a carrier-transporting substance, a binder, and an additive. Usable materials can be used in a range that does not impair the function as. The thickness of the formed intermediate layer is 10 μm or less, preferably 1 μm or less.

The electrophotographic photoreceptor according to the present invention can employ other known techniques. For example, the photosensitive layer may include a sensitizer. Suitable sensitizers include Lewis acids and dye dyes that form a charge transfer complex with the organic photoconductive substance. In addition, the film formability and flexibility of the photosensitive layer,
Additives such as plasticizers, ultraviolet absorbers, antioxidants, lubricants, adhesion promoters, dispersants, etc. can be added as needed to improve mechanical strength and the like. A carrier generating layer or a carrier generating substance can be added within a range that does not impair the characteristics.

In the present invention, an ordinary coating method is applied to the formation of the carrier generation layer, the carrier transport layer, the intermediate layer or the surface layer.

[0025]

The present invention is characterized in that an azo compound having a specific composition represented by Chemical Formula 1 is used as a carrier-generating substance constituting a laminated or dispersed electrophotographic photosensitive member. The azo compound exhibits an excellent effect on carrier generation,
Improves various characteristics such as charging characteristics, charge holding power, sensitivity performance, image forming properties, residual potential, etc. when used as a lamination type or dispersion type electrophotographic photoreceptor. In addition, since the film characteristics are good, characteristics due to repeated use Less deterioration phenomenon, heat, temperature,
It functions effectively to exhibit stable performance against environmental changes such as light. Therefore, it is possible to supply a high-performance and long-lasting electrophotographic photosensitive member.

[0026]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to examples. In each example, "parts" means "parts by weight".

Example 1 1 part of the compound (1) shown in Table 1 and 1 part of a polyester resin ("Vylon 200", manufactured by Toyobo Co., Ltd.) were placed in a ball mill together with 50 parts of tetrahydrofuran and thoroughly stirred and dispersed. Thereafter, the dispersion was applied to an aluminum plate surface using a fire coater and dried with hot air at 120 ° C. for 30 minutes to form a carrier generating layer having a thickness of about 0.3 μm. Then, 5 parts of p-diethylaminobenzaldehyde-N, N-diphenylhydrazone and a polycarbonate resin [manufactured by Teijin Chemicals Ltd., "Vanlite L-12"
50 "], and a solution prepared by dissolving 5 parts in 70 parts of 1,2-dichloroethane was applied and dried for 3 hours with warm air at 60 ° C.
An 8 μm carrier transport layer was formed.

The photoreceptor produced in this way was
C. and RH (relative humidity) of 55%, and after adjusting the humidity, an electrostatic paper tester ["SP-4" manufactured by Kawaguchi Electric Works, Ltd.
28 "] and corona-charged at a voltage of -5 KV in a static mode, and kept in a dark place for 10 seconds. Subsequently, the sample was exposed to tungsten as a light source so that the illuminance of the sample surface became 5.0 lux. When the evaluation was performed, the following results were obtained, where V ₀ is the initial charging voltage, V _D10 was the potential holding ratio in a dark place for 10 seconds, and E was
_1/2 is the half-exposure amount (the same applies hereinafter). _{V 0: -750 (V) V} D10: 90 (%) E 1/2: 2.1 lux sec.

Example 2 A photoconductor was prepared under the same conditions as in Example 1 except that the compound (2) shown in Table 1 was used. When the characteristics of this photoreceptor were measured in the same manner as in Example 1, the following results were obtained. _{V 0: -690 (V) V} D10: 89 (%) E 1/2: 1.9 lux sec.

Example 3 1.5 parts of the compound (3) shown in Table 1 and 1 part of a polyester resin ("Vylon 200" manufactured by Toyobo Co., Ltd.) were placed in a ball mill together with 250 parts of 1,2-dichloroethane and stirred and dispersed. After that, the dispersion was applied to a polyester film surface on which aluminum was deposited, and dried with hot air at 120 ° C. for 30 minutes to form a carrier generating layer having a thickness of about 0.5 μm. On the obtained carrier generation layer, 9-ethylcarbazole-
A solution prepared by dissolving 10 parts of 3-carbaldehyde-N, N-diphenylhydrazone and 10 parts of a polyester resin in 100 parts of 1,2-dichloroethane is applied, dried with warm air at 60 ° C. for 3 hours, and dried to a thickness of 15 μm. A carrier transport layer was formed.

When the characteristics of the photoreceptor thus manufactured were measured in the same manner as in Example 1, the following results were obtained. _{V 0: -830 (V) V} D10: 97 (%) E 1/2: 4.0 lux sec.

Example 4 2 parts of the compound (2) shown in Table 1 and 1 part of a polyester resin (manufactured by Toyobo Co., Ltd., "Vylon 200") were placed in a ball mill together with 100 parts of tetrahydrofuran, stirred and dispersed, and then dispersed. Was applied to a polyester film surface on which aluminum was deposited, and dried with hot air at 120 ° C. for 30 minutes to form a carrier generating layer having a thickness of about 0.5 μm. Next, the hydrazone compound 10 shown in Chemical formula 27 is formed on the carrier generation layer.
Section and polycarbonate resin [L-12 made by Teijin Chemicals Ltd.
50 ″] A solution prepared by dissolving 10 parts in 100 parts of 1,2-dichloroethane was applied and dried with warm air at 60 ° C. for 3 hours to form a carrier transport layer having a thickness of 15 μm.

[0033]

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The photoreceptor thus produced was used in Example 1.
When the characteristics were measured in the same manner as in the above, the following results were obtained. _{V 0: -710 (V) V} D10: 90 (%) E 1/2: 1.8 lux sec.

Examples 5 to 25 In place of compound (2) of Example 4, compounds of Table 11 selected from the group of compounds shown in Tables 1 to 10 were used, and the other conditions were the same as in Example 4. The body was made. Table 11 shows the characteristics of the obtained photoconductors.

[0036]

[Table 11]

Example 26 With respect to the photoreceptor prepared in Example 1, a change in characteristics was measured by repeating a charge-discharge cycle 10,000 times. In this case, the characteristics at the 1000th and 10000th time are as shown in Table 12, and showed excellent stability.

[0038]

[Table 12]

A mirror-finished aluminum drum was dip-coated on the pigment dispersion prepared in Example 1 and dried with hot air at 110 ° C. for 30 minutes to form a 0.3 μm charge generation layer. The charge transfer material solution prepared in Example 1 was dip-coated thereon and dried with warm air at 80 ° C. for 3 hours to form a charge transfer layer having a thickness of 20 μm. The obtained photoreceptor was mounted on a commercially available copying machine and tested for image characteristics. The surface potential was adjusted to -700 V by corona charging, and after image exposure, development, transfer, blade cleaning, and light removal were performed. As a result, an image with sufficient contrast and excellent gradation was obtained. This copy test was repeated 1000 times, and no change in the image was observed.

[0040]

As described above, according to the present invention, by using an azo compound having a specific composition as a carrier-generating substance, various characteristics such as charging characteristics, charge holding power, sensitivity performance, image forming properties, and residual potential are excellent. In addition, an electrophotographic photoreceptor that exhibits stable performance with no characteristic fluctuation even after long-term repeated use can be obtained. Therefore, it is possible to provide a high-performance and durable laminated or dispersed electrophotographic photosensitive member.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Masaru Hasegawa 5-52-12 Yoyogi, Shibuya-ku, Tokyo (56) References JP-A 1-177041 (JP, A) JP-A 4-245256 (JP, A )

Claims (2)

(57) [Claims] 1. An electrophotographic photoreceptor having a photosensitive layer, wherein the photoreceptor contains an azo compound having at least one azo group bonded to a coupler residue represented by the following general formula in the molecule. An electrophotographic photosensitive member characterized by the following. Embedded image Wherein X is a group of atoms necessary for forming a substituted or unsubstituted aromatic hydrocarbon ring or aromatic heterocyclic ring by condensing with a benzene ring, R ₁ is hydrogen, and R ₂ is substituted or unsubstituted. It represents an alkyl group, a substituted / unsubstituted aralkyl group, a substituted / unsubstituted aromatic hydrocarbon ring group or a substituted / unsubstituted aromatic heterocyclic group. 2. The photosensitive layer contains a carrier-generating substance and a carrier-transporting substance, wherein the carrier-generating substance is an azo compound having at least one azo group bonded to a coupler residue represented by the general formula: The electrophotographic photosensitive member according to claim 1.