JP2990981B2 - 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 an electrophotographic photoreceptor, and more particularly, to an electrophotographic photoreceptor made of an organic material and having excellent stability and durability, and in particular, excellent potential stability when used repeatedly and continuously.

[0002]

2. Description of the Related Art Conventionally, as an electrophotographic photoreceptor (hereinafter also simply referred to as a photoreceptor), an inorganic photoreceptor using an inorganic photoconductive material such as selenium, a selenium alloy, zinc oxide or cadmium sulfide as a photosensitive material. Has been widely used. On the other hand, an organic photoreceptor made of an organic material using an organic photoconductive substance has been developed and put to practical use, focusing on advantages such as flexibility, thermal stability, film forming property, and low cost. . For example, poly-N-vinylcarbazole and 2,4
A photoreceptor comprising 7-trinitrofluoren-9-one (U.S. Pat. No. 3,484,237), a photoreceptor containing an organic pigment as a main component (JP-A-47-37543), and a eutectic complex comprising a dye and a resin are used. Photoreceptor containing main component
No. 10735). Such an organic photoreceptor
Despite having many advantages, it was not widely used because of its inferior sensitivity and durability to inorganic photoreceptors, but in recent years, photoreceptors with excellent chargeability and sensitivity have been developed and rapidly spread. Have been doing.

[0003]

A photoreceptor is repeatedly used in an electrophotographic image forming process, and is required to always have stable photoreceptor characteristics. However, with respect to such stability and durability, at present, organic photoconductors have not yet sufficiently responded to market demands. That is, as it is repeatedly used, the potential decreases, the residual potential increases,
There is a problem that a change in sensitivity or the like occurs, the quality of an output image or printing deteriorates, and the image cannot be used.

An object of the present invention is to solve the above-mentioned problems and to provide an organic photoreceptor excellent in stability and durability, particularly in the stability of the potential when used repeatedly and continuously. .

[0005]

According to the present invention, at least one of the hydrazone compounds represented by the following general formula (I) and the benzidine compound represented by the following general formula (III) are provided. This problem can be solved by providing a photosensitive member having a photosensitive layer containing at least one kind as a charge transport material.

Further, the above-mentioned problem comprises at least one kind of a hydrazone compound represented by the following general formula (II) and at least one kind of a benzidine compound represented by the following general formula (III) as a charge transporting substance. The problem can also be solved by using a photoreceptor having a photosensitive layer.

[0007]

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[0008]

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[In the formulas (I) and (II), R1 represents an aryl group which may have a substituent, and R2 represents a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, or a halogen atom. Indicates either one. R3, R4 and R5 are each a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxyl group, a hydroxy group, a nitro group or an allyl group, an aryl group or an aralkyl group which may have a substituent. It represents either, a _r represents a substituted condensed polycyclic aromatic hydrocarbon may have a substituent. ]

[0010]

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[In the formula (III), Z1 represents a hydrogen atom or an alkyl group having 1 to 2 carbon atoms. Z2 and Z3 represent any of a hydrogen atom, an alkyl group having 1 to 2 carbon atoms, and a halogen atom. ]

[0012]

The hydrazone compound represented by the general formula (I) as the charge transport material and the benzidine compound represented by the general formula (III) are mixed and used, or the compound represented by the general formula (II) is used. By using a mixture of the hydrazone compound represented by the formula (1) and the benzidine compound represented by the general formula (III), the stability and durability, especially when used continuously, are higher than when each compound is used alone. It becomes possible to obtain a photosensitive member having excellent potential stability.

[0013]

EXAMPLES Specific examples of the hydrazone compounds represented by the above general formulas (I) and (II) are as follows.

[0014]

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[0015]

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[0016]

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Further, specific examples of the benzidine compound represented by the general formula (III) are as follows.

[0018]

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The photoreceptor of the present invention contains at least one kind of these hydrazone compounds and at least one kind of benzidine compound and contains them as a charge transport material in the photosensitive layer. Fig. 1
And two types shown in FIG.

FIG. 1 is a conceptual cross-sectional view of one embodiment of the photoreceptor of the present invention, in which a binder resin containing a charge generating substance 21 is formed on a conductive substrate 1 via an undercoat layer 3. Function-separated laminated photoreceptor provided with a laminated photosensitive layer 2a in which a charge transport layer 24 composed of a binder resin containing a hydrazone compound and a benzidine compound as a charge transport material 23 and a charge transport material 23 are sequentially laminated. It is. The photosensitive member having this configuration is generally used in a negative charging system.

FIG. 2 is a conceptual cross-sectional view of another embodiment of the photoreceptor of the present invention, in which a hydrazone as a charge generating substance 21 and a charge transporting substance 23 is provided on a conductive substrate 1 via an undercoat layer 3. This is a single-layer type photoconductor provided with a single-layer photosensitive layer 2b made of a binder resin containing a compound and a benzidine compound. In addition, the undercoat layer 3 in FIGS.
Is provided as needed and may not be provided.

The conductive substrate 1 serves as a photoreceptor electrode and at the same time serves as a support for the other layers, such as aluminum, an aluminum alloy, stainless steel or the like, or glass or resin. The surface of which is subjected to a conductive treatment is used. The undercoat layer 3 is provided between the conductive substrate and the photosensitive layer and has a function of increasing the barrier function and the adhesiveness of the carrier, if necessary, and includes casein, polyvinyl alcohol, polyvinyl methyl ether, It can be formed of poly-N-vinylimidazole, ethylcellulose, ethylene-acrylic acid copolymer, phenol resin, polyamide, polyurethane, gelatin, aluminum oxide, or the like. The thickness of the undercoat layer is preferably in the range of 0.05 μm to 20 μm, particularly preferably in the range of 0.05 μm to 10 μm.

The charge generating layer 22 is prepared by dispersing the charge generating substance 21 together with a binder resin in an amount of 0.3 to 2 times the amount thereof in a solvent using a homogenizer, an ultrasonic wave, a ball mill, a sand mill, a paint shaker, or the like. Is formed by coating and drying the dispersion. The film thickness is 0.01
The range of μm to 3 μm, particularly 0.05 μm to 1 μm is preferred. Metal-free phthalocyanine,
Phthalocyanine compounds such as titanyl phthalocyanine,
Various pigments such as azo, quinone and indigo, dyes such as cyanine, squarylium, azurenium and pyrylium compounds, selenium and selenium compounds are used, and a suitable substance is selected and used according to the wavelength region of exposure light. Examples of the binder resin include polyvinyl butyral, polyarylate, polycarbonate, polyester, phenoxy resin, polyvinyl acetate, epoxy resin, acrylic resin, polyacrylamide resin, polyamide, polyvinyl pyridine, cellulose, urethane resin, casein, polyvinyl alcohol, and polyvinyl. Resins such as pyrrolidone can be mentioned. Examples of the solvent include alcohols such as methanol, ethanol, and isopropyl alcohol;
Ketones such as acetone, methyl ethyl ketone and cyclohexanone, N, N-dimethylformamide, N, N-
Amides such as dimethylacetamide, ethers such as tetrahydrofuran, dioxane, ethylene glycol dimethyl ether, dimethoxyethane and propylene oxide, esters such as methyl acetate, ethyl acetate and dimethyl carbonate, chloroform, dichloromethane,
Aliphatic hydrogen halides such as dichloroethylene and trichloroethylene, or aromatics such as benzene, toluene, xylene and monochlorobenzene can be used.

The charge transport layer 24 is formed by dissolving the above-mentioned hydrazone compound and benzidine compound as the charge transport substance 23 together with a suitable binder resin in a solvent, if necessary, applying the solution and drying. Is done.
The film thickness is preferably in the range of 10 μm to 50 μm, particularly preferably 15 μm to 40 μm. The total amount of the hydrazone compound and the benzidine compound in the charge transport layer is from 30% by weight to 70% by weight, especially from 40% by weight to 60% by weight, based on the total solid content in the charge transport layer.
A range of weight% is preferred. The mixing ratio of the hydrazone compound to the benzidine compound is 5:95 to 9 by weight.
5: 5, preferably 60:40 to 20:80. As the binder resin, for example, acrylic resin, polyarylate, polyester, polycarbonate, polystyrene, acrylonitrile-styrene copolymer, polyvinyl butyral, polyvinyl formal, polyacrylamide, polyamide and the like can be used. Further, the same solvent as that used for the charge generation layer can be used.

The single-layer photosensitive layer 2b shown in FIG.
A mixture of a hydrazone compound and a benzidine compound as the charge transport material 23 in an amount of 1 and 2 to 10 times the amount thereof is dissolved and dispersed in a suitable solvent together with a suitable binder resin,
It is formed by applying and drying the liquid. The film thickness is preferably in the range of 10 μm to 40 μm, particularly preferably 15 μm to 25 μm.

Hereinafter, specific embodiments of the present invention will be described, but the present invention is not limited to the following embodiments. Parts in Examples are parts by weight. Example 1 A conductive substrate had a length of 30 mm, a width of 30 mm, and a thickness of 1 mm.
Was prepared. A coating solution of 4.5 parts of polyamide (Amilan CM8000, manufactured by Toray Industries, Inc.) dissolved in 150 parts of methanol was dip-coated on this plate, dried at 90 ° C. for 20 minutes, and dried under a thickness of 0.2 μm. A pull layer was provided.

Next, 2 parts of a disazo pigment represented by the following structural formula as a charge generating substance, 2 parts of a polyester resin (manufactured by Toyobo Co., Ltd .; Byron 200), and 9 parts of cyclohexanone 9
0 parts were mixed and dispersed with a sand grinder for 6 hours.
60 parts of tetrahydrofuran was added to this dispersion to dilute it to form a coating solution. This solution was dip-coated on the undercoat layer, and dried at 90 ° C. for 20 minutes to form a 0.4 μm-thick charge generating layer. .

[0028]

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Subsequently, the compound No. 1 as a charge transport material was used. 1.5 parts of the hydrazone compound of Compound 5 and the compound N
o. 1.5 parts of the benzidine compound of No. 17 was dissolved in 30 parts of tetrahydrofuran together with 3 parts of a bisphenol Z-type polycarbonate resin (number average molecular weight: 50,000) to form a coating solution, and this solution was coated on the charge generating layer with a wire bar. The resultant was dried at a temperature of 100 ° C. for 20 minutes to form a charge transport layer having a thickness of 20 μm. Thus, a laminated photoconductor having the configuration shown in FIG. 1 was produced.

Example 2 In Example 1, the compound N was used as a charge transport material.
o. Compound No. 5 in place of the hydrazone compound of No. 5
Example 1 except that 11 hydrazone compounds were used.
A photoreceptor was produced in the same manner as described above. Example 3 In Example 1, the compound N as the charge transport material was used.
o. 17 in place of the benzidine compound 17
o. A photoconductor was prepared by the same way as that of Example 1 except that 20 benzidine compound was used.

Example 4 In Example 1, the compound N was used as a charge transport material.
o. Compound No. 5 in place of the hydrazone compound of No. 5
The hydrazone compound of No. 11 was replaced with the aforementioned compound No. Compound No. 17 was replaced with Compound No. 17 A photoconductor was prepared by the same way as that of Example 1 except that 20 benzidine compound was used.

Comparative Example 1 In Example 1, the compound N was used as the charge transport material.
o. 5 and 1.5 parts of the hydrazone compound of Compound No. 5
No. 17 instead of using 1.5 parts of the benzidine compound. A photoconductor was prepared by the same way as that of Example 1 except that 3 parts of only hydrazone compound of No. 5 was used.

Comparative Example 2 In Example 1, the compound N was used as the charge transport material.
o. 5 and 1.5 parts of the hydrazone compound of Compound No. 5
No. 17 instead of using 1.5 parts of the benzidine compound. A photoconductor was prepared by the same way as that of Example 1 except that 3 parts of benzidine compound 17 alone was used.

With respect to the photoreceptor thus manufactured,
The sensitivity was evaluated, and as the repetition characteristics, changes in the charged potential and the residual potential when charging, exposure, and static elimination were repeatedly performed were examined. For these measurements, an electrostatic charging tester EPA8100 manufactured by Kawaguchi Electric Works was used. The surface of the photoreceptor is charged by performing a corona discharge at -6 kV for 10 seconds in a dark place, and then exposed with white light having an illuminance of 2 lux to obtain a half-attenuation which is an exposure amount necessary for the surface potential to be reduced to half of the initial value. The sensitivity was evaluated by _{calculating the} exposure amount E _1/2 (E _1/2
The smaller the value, the better the sensitivity). Next, a repetition process in which charging, exposure, and static elimination were defined as one cycle was repeated 5000 cycles, and the charged potential and residual potential before and after that were measured. As the residual potential, the surface potential after irradiating white light with an illuminance of 2 lux for 10 seconds was defined as the residual potential. Table 1 shows the measurement results.

[0035]

[Table 1]

As shown in Table 1, the charge transporting material of the charge transporting layer in the function-separated type photoreceptor was
The photoreceptor of Comparative Example 1 using the hydrazone compound alone showed a large increase in the residual potential due to repetition, and the photoreceptor of Comparative Example 2 using the benzidine compound alone showed a large decrease in the charged potential due to the repetition. In the photoreceptors of Examples 1 to 4 using a mixture of benzene and a benzidine compound, the charge potential and the residual potential by repetition are stable, and the effect of using the mixture as a charge transport material is apparent. It is.

Example 5 A conductive substrate was 30 mm long and 30 mm wide in the same manner as in Example 1.
An aluminum plate having a thickness of 1 mm and a thickness of 1 mm was prepared. On top of this, polyamide (manufactured by Teijin Chemicals Limited; Toresin MF-
30) A solution obtained by dissolving 4.5 parts in 150 parts of methanol is dip-coated, dried at 90 ° C. for 20 minutes, and dried to a thickness of 0.2 μ
m undercoat layer was provided. Next, the compound No. 1 as a charge transport material was used. No. 2 hydrazone compound and 1.5 parts of the compound No. 1.5 parts of the benzidine compound of No. 18 were dissolved in 60 parts of dichloromethane together with 4.5 parts of a polyvinyl butyral resin (manufactured by Sekisui Chemical Co., Ltd .; Eslec BX-2) as a binder resin, and this was used as a charge generating substance. Was added and dispersed in a ball mill for 20 hours. This dispersion was coated on the undercoat layer with a wire bar and dried at a temperature of 100 ° C. for 20 minutes to form a photosensitive layer having a thickness of 20 μm. The body was made.

Example 6 In Example 5, the compound N was used as a charge transport material.
o. In place of the hydrazone compound of Compound 2,
A photoconductor was prepared by the same way as that of Example 5 except that hydrazone compound of No. 9 was used. Example 7 In Example 5, the compound N was used as a charge transport material.
o. The compound N instead of the benzidine compound 18
o. A photoconductor was prepared by the same way as that of Example 5 except that the benzidine compound of No. 19 was used.

Example 8 In Example 5, the compound N was used as a charge transport material.
o. In place of the hydrazone compound of Compound 2,
Compound No. 9 was obtained using the hydrazone compound of No. 9. In place of the benzidine compound No. 18, the aforementioned compound No. A photoconductor was prepared by the same way as that of Example 5 except that the benzidine compound of No. 19 was used.

Comparative Example 3 In Example 5, the compound N was used as a charge transport material.
o. No. 2 hydrazone compound and 1.5 parts of the compound No.
Compound No. 18 was replaced with 1.5 parts of the benzidine compound. A photoconductor was prepared by the same way as that of Example 5 except that only 3 parts of hydrazone compound of No. 2 were used.

Comparative Example 4 In Example 5, the compound N was used as a charge transport material.
o. No. 2 hydrazone compound and 1.5 parts of the compound No.
Compound No. 18 was replaced with 1.5 parts of the benzidine compound. A photoconductor was prepared by the same way as that of Example 5 except that only 3 parts of 18 benzidine compound were used.

With respect to the photoreceptor thus obtained,
The sensitivity was evaluated in the same manner as in Example 1 except that the voltage of the corona discharge was changed to +6 kV, and the repetition characteristics were as follows: charge potential, residual potential, and charge potential when charge, exposure, and charge removal were repeatedly performed. The variation was examined. Table 2 shows the results.

[0043]

[Table 2]

As can be seen from Table 2, even in the single-layer type photoreceptor, in the photoreceptor of Comparative Example 3 in which the hydrazone compound was used alone as the charge transport material of the photosensitive layer, the residual potential increased due to repetition. In the photoreceptor of Comparative Example 4 in which the benzidine compound was used alone, the charge position was significantly reduced by repetition. However, in the photoreceptors of Examples 5 to 8 in which the hydrazone compound and the benzidine compound were used in combination, The charge position and the residual potential by repetition are stable, and the effect of mixing and using both as the charge transport material is apparent.

[0045]

According to the present invention, at least one of the hydrazone compounds represented by the general formula (I) and at least one of the benzidine compounds represented by the general formula (III) are used as charge transporting substances. A photosensitive member provided with a photosensitive layer comprising the same. Alternatively, a photosensitive layer having a photosensitive layer containing at least one of the hydrazone compounds represented by the general formula (II) and at least one of the benzidine compounds represented by the general formula (III) as a charge transporting substance. Body. In this way, by using a mixture of the two as the charge transporting material, it is possible to obtain a photoreceptor having a stable and durable, particularly stable potential when used repeatedly and continuously.

[Brief description of the drawings]

FIG. 1 is a conceptual sectional view of one embodiment of a photoreceptor of the present invention.

FIG. 2 is a conceptual sectional view of a different embodiment of the photoreceptor of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 conductive substrate 2 a laminated photosensitive layer 2 b single-layer photosensitive layer 3 undercoat layer 21 charge generating substance 22 charge generating layer 23 charge transporting substance 24 charge transporting layer

Claims (2)

(57) [Claims] 1. A photosensitive layer comprising, as a charge transporting material, at least one kind of a hydrazone compound represented by the following general formula (I) and at least one kind of a benzidine compound represented by the following general formula (III). An electrophotographic photoreceptor, comprising: 2. A photosensitive layer comprising at least one hydrazone compound represented by the following general formula (II) and at least one benzidine compound represented by the following general formula (III) as a charge transporting substance: An electrophotographic photoreceptor, comprising: Embedded image Embedded image [In the formulas (I) and (II), R1 represents an aryl group which may have a substituent, R2 represents a hydrogen atom, and has 1 to 3 carbon atoms.
Represents an alkyl group or a halogen atom. R3, R4 and R5 are each a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxyl group, a hydroxy group, a nitro group or an allyl group, an aryl group or an aralkyl group which may have a substituent. Represents one of
A _r represents a substituted condensed polycyclic aromatic hydrocarbon may have a substituent. ] [In the formula (III), Z1 represents a hydrogen atom or a carbon atom 1
Represents 2 to 2 alkyl groups. Z2 and Z3 represent any of a hydrogen atom, an alkyl group having 1 to 2 carbon atoms, and a halogen atom. ]