JP2983733B2 - Electrophotographic photoreceptor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

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

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2. Description of the Related Art Conventionally, inorganic photoconductive materials such as selenium, cadmium sulfide, zinc oxide and silicon have been known for electrophotographic photoreceptors, and have been widely studied and put to practical use. . While these inorganic materials have many advantages, they also have various disadvantages. For example, selenium has drawbacks in that production conditions are difficult, and crystallization is easily caused by heat and mechanical shock, and cadmium sulfide and zinc oxide have poor moisture resistance and durability. It has been pointed out that silicon is insufficient in chargeability and difficult to manufacture. In addition, selenium and cadmium sulfide have toxicity problems.

On the other hand, organic photoconductive materials have good film-forming properties, excellent flexibility, are lightweight, have good transparency, and are sensitive to a wide wavelength range by an appropriate sensitization method. Due to its advantages such as easy design of the body, its practical use is gradually attracting attention.

Incidentally, the photoreceptor used in the electrophotographic technology is generally required to have the following basic properties. That is, (1) high chargeability against corona discharge in a dark place, (2) little leakage (dark decay) of the obtained charge in a dark place, and (3) charge charge by light irradiation. (4) The residual charge after light irradiation is small.

However, many studies have been made on photoconductive polymers such as polyvinyl carbazole as organic photoconductive substances to date, but these have not always had sufficient film-forming properties, flexibility and adhesiveness. Also, it is difficult to say that the above-mentioned basic properties of the photoreceptor are sufficiently provided.

On the other hand, as for the organic low-molecular-weight photoconductive compound, a photoreceptor having excellent mechanical strength such as film property, adhesion and flexibility can be obtained by selecting a binder or the like used for photoreceptor formation. Although it can be obtained, it is difficult to find a compound that is suitable for retaining high-sensitivity properties.

In order to improve such a point, the carrier generation function and the carrier transport function are shared by different substances,
Organic photoreceptors having higher sensitivity characteristics have been developed. The feature of such a photoreceptor, which is called a function-separated type, is that a material suitable for each function can be selected from a wide range. Has been advanced.

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As described above, various improvements have been made in the preparation of an electrophotographic photoreceptor, but the basic properties and high durability required for the above-mentioned photoreceptor have been proposed. The one that satisfies such requirements has not yet been obtained.

SUMMARY OF THE INVENTION An object of the present invention is to provide an electrophotographic photoreceptor having high sensitivity, high durability, high charging potential, and almost no reduction in sensitivity even when used repeatedly, and having a stable charging potential. To provide.

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Means for Solving the Problems The present inventors have studied a photoconductive substance having high sensitivity and high durability, and as a result, it has been found that the novel azo compound represented by Chemical Formula 1 or 2 is effective. And found the present invention.

In Chemical Formulas ¹ and 2, R ¹ , R ² and R ³ represent a hydrogen atom, a halogen atom, an alkyl group or an alkoxy group which may have a substituent, and A represents a coupler residue.

Here, specific examples of R ¹ , R ² and R ³ include:
Examples thereof include a halogen atom such as a hydrogen atom, a fluorine atom, a chlorine atom and a bromine atom, an alkyl group such as a methyl group, an ethyl group and a 2-methoxyethyl group, and an alkoxy group such as a methoxy group and an ethoxy group.

Specific examples of the coupler residue A include those shown in Tables 1 to 7.

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[Table 1]

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Specific examples of the azo pigments useful in the present invention represented by Chemical Formulas 1 and 2 include those having the following structural formulas.

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The azo pigments represented by Chemical Formulas 1 and 2 are
The diamine of the amine represented by Chemical formula 44 (wherein R ¹ , R ² , and R ³ are the same as Chemical formulas ¹ and ² ) is diazotized by a conventional method, and then, in the presence of a coupler and an alkali, It can be obtained by reacting.

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Next, a synthesis example will be specifically described. Synthesis Example 1 (Synthesis of Exemplified Compound 15 (A = A-31)) Diamine obtained by reducing a condensate of 4-nitrophthalic anhydride and 4-amino-4'-nitrostilbene (melting point: 252.3) 0.325 g in DMF
(50 ml) and concentrated hydrochloric acid (0.37 ml) is added. To this, at about 5 ° C, sodium nitrite (0.1
5 g) of an aqueous solution (0.5 ml) was added. 20 at the same temperature
After further stirring at room temperature for 10 minutes,
DM of 3-hydroxy-2-naphthoic acid 4-chloroanilide (0.60 g) and triethanolamine (1 g)
The solution was added dropwise to the F (50 ml) solution at 5 to 10 ° C over 10 minutes. After stirring at the same temperature for 2 hours and further at room temperature for 2 hours, the precipitate was collected by filtration, and 100 ml each of DMF, acetone and water.
l. Yield 0.52g Yield 54% Melting point 250 ° C or more

Synthesis Example 2 (Example Compound 27 (A = A-2)
Synthesis of 1) 0.41 g of a diamine (melting point: 250 ° C. or higher) obtained by reducing a condensate of 3-nitronaphthalic anhydride and 4-amino-4′-nitrostilbene was added to DMF.
(50 ml) and concentrated hydrochloric acid (0.37 ml) is added. To this, at about 5 ° C, sodium nitrite (0.1
5 g) of an aqueous solution (0.5 ml) was added. 20 at the same temperature
After further stirring at room temperature for 10 minutes,
DM of 3-hydroxy-2-naphthoic acid 2-chloroanilide (0.60 g) and triethanolamine (1 g)
The solution was added dropwise to the F (20 ml) solution at 5 to 10 ° C over 10 minutes. After stirring at the same temperature for 2 hours and further at room temperature for 2 hours, the precipitate was collected by filtration, and 100 ml each of DMF, acetone and water.
l. Yield 0.78g Yield 76% Melting point 250 ° C or more

The electrophotographic photoreceptor of the present invention can be obtained by containing one or more azo compounds represented by Chemical Formulas 1 and 2. Various types of photoconductors are known, and any of them can be used. For example, there is a conductive support in which a photosensitive layer containing an azo compound, a known charge transport material, and a film-forming binder resin is provided. In addition, a laminated photoreceptor in which a charge generation layer containing an azo compound and a binder resin and a charge transport layer containing a charge transport substance and a binder resin are provided on a conductive support is also known. Either of the charge generation layer and the charge transport layer may be an upper layer. As a support for preparing a photoreceptor using the compound of the present invention, a metal drum, a metal plate, a paper subjected to conductive processing, a sheet of a plastic film, a drum or a belt, and the like are used. .

The film-forming binder resin used for forming the photosensitive layer on the support may be of various types depending on the field of use. For example, the use of a photoreceptor for copying includes polystyrene resin, polyvinyl acetal resin, polysulfone resin, polycarbonate resin, polyester resin, polyphenylene oxide resin, polyarylate resin, acrylic resin, methacrylic resin, and phenoxy resin. Among these, polystyrene resin, polyvinyl acetal resin, polycarbonate resin, polyester resin, polyarylate resin, and the like are excellent in potential characteristics as a photoconductor. These resins can be used alone or as a mixture of two or more of them as a copolymer.

The content of these resins contained in the photosensitive layer is preferably from 10 to 500% by weight based on the azo pigment, and from 50 to 1% by weight.
50% by weight is more preferred. If the ratio of the resin is too high, the charge generation efficiency is lowered, and if the ratio of the resin is too low, there is a problem in film formability.

Some of these resins include tension, bending,
Some have weak mechanical strength such as compression. To improve this property, substances which impart plasticity can be added. Specifically, phthalic acid esters (eg, DOP, DOP
BP, etc.), phosphate esters (eg, TCP, TOP
Etc.), sebacic esters, adipic esters, nitrile rubbers, chlorinated hydrocarbons and the like. If these substances are added unnecessarily, they adversely affect the electrophotographic properties. Therefore, the ratio is preferably 20% or less based on the binder resin.

In addition, an antioxidant, an anti-curl agent and the like can be added as necessary to the photoreceptor.

The charge transport material includes a hole transport material and an electron transport material. An example of the former is, for example, Japanese Patent Publication No. 34-5
Oxadiazoles disclosed in JP-B-466-466, triphenylmethanes disclosed in JP-B-45-555, pyrazolines described in JP-B-52-4188, and JP-B-55-42380. And oxadiazoles described in JP-A-56-123544, and JP-B-58-3237.
And the stilbenes disclosed in JP-A-58-198043. On the other hand, as the electron transporting substance, for example, chloranil, tetracyanoethylene, 2,2
4,7-trinitro-9-fluorenone, 2,4,5
Examples include 7-tetranitroxanthone, 1,3,7-trinitrodibenzothiophene, and the like. These charge transport materials can be used alone or in combination of two or more.

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EXAMPLES Next, the present invention will be described in more detail with reference to Examples, but the present invention is not limited thereto.

Example 1 1 part by weight of Exemplified Compound 15 (A = A-21) and 1 part by weight of a polyester resin (Vylon 200 manufactured by Toyobo) were mixed with 100 parts by weight of tetrahydrofuran, and mixed with glass beads using a paint conditioner. Time dispersed. The dispersion thus obtained was applied on an aluminum-evaporated polyester using an applicator to form a charge generation layer having a thickness of about 0.2 μm. Next, p-dibenzylaminobenzaldehyde = diphenylhydrazone was mixed with a polyarylate resin (U-polymer manufactured by Unitika) at a weight ratio of 1: 1 to form a 10% solution using dichloroethane as a solvent.
The above charge generation layer was coated with an applicator to form a charge transport layer having a film pressure of about 20 μm.

The laminated type photoreceptor thus prepared is
Electrophotographic characteristics were evaluated using an electrostatic recording tester (SP-428, manufactured by Kawaguchi Electric Co., Ltd.). Measurement conditions: applied voltage -6k
V, Static No. 3 (turntable rotation speed mode: 10 m / min). As a result, the half-life exposure amount was 2.2 lux · sec, which was a high sensitivity value.

Further, the same apparatus was used to evaluate characteristics for repeated use in which charge-discharge (static light: irradiation with white light, 400 lux × 1 second irradiation) was performed in one cycle. 1000
The change in the charged potential due to the repetition of
The initial potential at the 1000th time was −600 V, compared to the initial potential at −620 V at the time of the experiment, and it was found that the potential was not reduced by repetition and was stable.

Examples 2 to 9 A laminated photoreceptor was prepared in the same manner as in Example 1 except that the azo compounds shown in Table 8 were used instead of the azo compounds used in Example 1. Using this photoreceptor, under the same conditions as in Example 1, the light half-life exposure amount E1 / 2 (lux · second) and the initial potential Vo after the first and 1000 repetitions were repeated.
(V) was measured. The results are shown in Table 8.

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[Table 8]

Comparative Examples 1 to 7 A photoconductor was prepared in the same manner as in Example 1 except that the following comparative compounds 45 to 48 were used instead of the compounds used in Example 1, and the characteristics were evaluated. . Table 9 shows the results.

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[Table 9] *: (Looks and seconds)

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As is apparent from the above, according to the present invention, an electrophotographic photosensitive member having high sensitivity and high durability can be provided.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-63-66561 (JP, A) JP-A-63-64053 (JP, A) JP-A-63-37354 (JP, A) JP-A-1- 252966 (JP, A) JP-A-4-361267 (JP, A) JP-A-4-362652 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) G03G 5/06 340- 369 CA (STN) REGISTRY (STN)

Claims (1)

(57) [Claims] An electrophotographic photoreceptor comprising an azo compound represented by the following formula 1 or 2 on a conductive support. Embedded image Embedded image (In Chemical Formulas ¹ and 2, R ¹ , R ² , and R ³ represent a hydrogen atom, a halogen atom, an alkyl group or an alkoxy group which may have a substituent, and A represents a coupler residue.)