JP3130158B2 - 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 photosensitive member, and more particularly to an electrophotographic photosensitive member having a photosensitive layer containing a specific charge generating substance and a specific charge transporting substance.

[0002]

2. Description of the Related Art Conventionally, as an electrophotographic photosensitive member,
Those having a photosensitive layer mainly composed of an inorganic photoconductor such as selenium, cadmium sulfide, zinc oxide, and silicon have been widely known. However, they are not always satisfactory in sensitivity, thermal stability, moisture resistance, durability and the like, and in particular, selenium and cadmium sulfide have restrictions in production and handling due to their toxicity.

On the other hand, an electrophotographic photosensitive member having a photosensitive layer containing an organic photoconductive compound as a main component is relatively easy to manufacture, inexpensive, easy to handle, and generally selenium photosensitive. It has many advantages, such as better thermal stability than the body, and has attracted much attention in recent years.

[0004] Such organic photoconductive compounds include:
Poly-N-vinylcarbazole is well known, and has an electrophotographic photosensitive member having a photosensitive layer mainly composed of a charge transfer complex formed from the compound and a Lewis acid such as 2,4,7-trinitro-9-fluorenone. The body is Tokuboku 50-10496
No., published in Japanese Unexamined Patent Publication No. However, this photoreceptor was not always satisfactory in sensitivity, film formability, and durability.

On the other hand, an electrophotographic photosensitive material containing a low molecular weight organic photoconductor obtained by combining a charge transfer agent represented by triphenylamines, stilbenes and hydrazones with a charge generating agent such as phthalocyanine and azo pigments. The body has been proposed. Combine these with an appropriate binder,
Further, by combining a compound having a high charge generation ability and a compound having a high charge transfer ability as, for example, a laminated photoreceptor, there has been developed a compound having a sensitivity close to that of an inorganic photoreceptor such as selenium. As a result, photoconductors containing such an organic photoconductive compound as a main component have largely entered the field of copying machines and printers.

[0006] A layered or dispersed function-separated type photoreceptor in which the charge generation function and the charge transfer function are shared by separate substances, respectively, has a wide selection range of each material, and has a wide charging range, charging characteristics, sensitivity and durability. It has the advantage that an electrophotographic photoreceptor having any desired electrophotographic characteristics such as properties can be relatively easily prepared.

Conventionally, various types of charge generating substances or charge transfer substances have been proposed. For example, an electrophotographic photoreceptor having a photosensitive layer in which a charge generation layer made of amorphous selenium and a charge transfer layer containing poly-N-vinylcarbazole as a main component has been put to practical use. However, the charge generation layer made of amorphous selenium has a drawback of poor durability. Various uses of organic dyes and pigments as charge generating substances have been proposed. For example, as an electrophotographic photoreceptor containing a monoazo pigment or a disazo pigment in a photosensitive layer, JP-B-48-30513, JP-A-52-4241, JP-A-54-46558, and JP-B-56-11945 have already been known.

[0008] However, there are only a few practically usable photoreceptors of the function-separated type, and many required characteristics such as charging characteristics, sensitivity, residual potential, pre-exposure characteristics, and repeated use characteristics. It is difficult to say that we are satisfied with everything. It can be said that these properties largely depend on the performance of each of the charge generation material and the charge transfer material, but it is also known that the selection of a suitable combination thereof is important, and many proposals have been made. . The reason may be that such selection is not based on theoretical grounds, but is made by trial and error.

[0009]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a function-separated type electron-emitting device having a high sensitivity and a high charging potential. An object of the present invention is to provide a photoreceptor.

[0010]

As a result of various studies to achieve the above object, the present inventor has found that a phthalocyanine pigment is contained in an electrophotographic photoreceptor as a charge generating material, and a general formula is used as a charge transfer material. It has been found that it is effective to contain a stilbene compound represented by Chemical formula 1, and the present invention has been accomplished.

As the phthalocyanine pigment, metal-free phthalocyanine and various metal phthalocyanines are used, and particularly, metal-free phthalocyanine, oxytitanium phthalocyanine, copper phthalocyanine, and diphenoxygermanium phthalocyanine are preferable.

In the chemical formula 1, Ar represents an aryl group which may have a substituent, and R ₁ and R ₂ represent an alkyl group, an aralkyl group, an aryl group and a heterocyclic group which may have a substituent. R ₃ represents a hydrogen atom or a lower alkyl group;
R ₄ , R ₅ , and R _{6 each} represent a hydrogen atom or an optionally substituted alkyl group, aryl group, or heterocyclic group;
₇ , R ₈ and R ₉ represent a hydrogen atom, a halogen atom, or a lower alkyl group.

Here, specific examples of Ar include aryl groups such as phenyl group, methoxyphenyl group, tolyl group, chlorophenyl group, and naphthyl group. Specific examples of R ₁ and R ₂ include methyl group, Butyl group, alkyl group such as 3-methyloctyl group, benzyl group, 4-methylbenzyl group, aralkyl group such as 2-chlorophenethyl group, phenyl group, tolyl group, chlorophenyl group, aryl group such as naphthyl group, or A heterocyclic group such as a pyridyl group or an indolyl group, and specific examples of R ₃ include a hydrogen atom,
Alternatively, a lower alkyl group such as a methyl group, an ethyl group, or a propyl group, and specific examples of R ₄ , R ₅ , and R ₆ include a hydrogen atom, a methyl group, a butyl group, and a 2-methylhexyl group. Alkyl group such as phenyl group, methoxyphenyl group, tolyl group, chlorophenyl group, aryl group such as naphthyl group, or heterocyclic group such as pyridyl group, indolyl group, or R ₇ , R ₈ , and R ₉ Specific examples include a hydrogen atom, a halogen atom such as fluorine, chlorine, and bromine, and a lower alkyl group such as a methyl group and an ethyl group.

The compounds represented by Chemical Formula 1 can be produced by the methods of the following synthetic examples. Synthesis Example (Synthesis of Exemplified Compound 3)

[0015]

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The aldehyde compound of the formula (10.0 g) and 4
-To a DMF solution (250 ml) of styrylbenzyltriphenylphosphonium bromide (14.2 g)
After adding potassium t-butoxide (4.47 g) and stirring at room temperature overnight (about 14 hours), the reaction solution was poured into 1000 ml of ice water, and the precipitated crystals were collected by filtration. This was washed with water, dried, and purified by column chromatography to obtain 8.2 g of a crystal of Exemplified Compound 3.

Melting point: 154.0 to 156.0 ° C., yield: 60
%. NMR (δ, ppm, CDCl ₃ ) 7.2-7.6 (m, 16H), 6.8-7.2 (m,
16H), 6.71 (d, 1H)

Next, stilbene compounds according to the present invention will be exemplified, but the present invention is not limited thereto.

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The electrophotographic photoreceptor according to the present invention is obtained by containing a phthalocyanine pigment as a charge generating substance and a stilbene compound as described above as a charge transfer substance, and has excellent performance.

Hereinafter, each component of the present invention will be described in detail. First, as the conductive support on which the photosensitive layer of the photoreceptor is formed, any of those used for a well-known electrophotographic photoreceptor can be used. Specifically, for example, gold, silver,
Drums, sheets and belts of platinum, titanium, aluminum, copper, zinc, iron, metal oxides and the like subjected to conductive treatment, and laminates and vapor-deposits of these thin films.

Further, metal powder, metal oxide, carbon black, carbon fiber, copper iodide, charge transfer complex, inorganic salt,
Drums, sheets, belts, etc. made of plastics, ceramics, papers, etc., which have been coated with a conductive material such as an ion-conductive polymer electrolyte together with a suitable binder and embedded in a polymer matrix and have been subjected to a conductive treatment. Drums, sheets, belts, and the like of plastics, ceramics, paper, and the like that contain conductive materials and are made conductive.

The photosensitive layer is of a single layer type in which a charge generating substance and a charge transporting substance are dispersed and mixed and confined in a binder, and a laminated type in which the charge generating substance and the charge transporting substance are separated and sealed in a binder. Although the present invention can be applied to any system, it is preferably used in a system of a function-separated type laminated photoreceptor in which the performance of the charge generation material and the charge transfer material is easily maximized.

A blocking layer may be provided between the photosensitive layer and the conductive support to control the injection of electric charge from the photosensitive layer to the conductive support. A surface layer may be provided in order to improve the density.

In the layered photoreceptor of the function-separated type, the charge generation layer is composed of at least a mixed system of a phthalocyanine pigment and a binder resin as a charge generation substance, or a vapor deposition film of a phthalocyanine pigment by a vacuum vapor deposition apparatus. Polymers and copolymers of vinyl compounds such as styrene, vinyl acetate, acrylates, methacrylates, silicone resins, phenoxy resins, butyral resins, butyral resins, formal resins, phenol resins, polycarbonates, polyarylates, and polyamides as binder resins ,
Examples thereof include thermosetting resins such as polyimide, epoxy resin, and urethane resin, and photocurable resins. The binder is used in an amount of 1 to 1000 parts by weight, preferably 1 to 400 parts by weight, based on 100 parts by weight of the charge generating substance (phthalocyanine pigment). The thickness of the charge generation layer is preferably from 0.1 to 20 μm.

The stilbene compound represented by the general formula 1 is used as a charge transfer material in the present electrophotographic photoreceptor. For example, it is contained in the charge transfer layer in a laminated electrophotographic photosensitive member. In this case, the charge transfer layer comprises at least a stilbene compound represented by the general formula 1 and a binder.

Examples of the binder resin used for the charge transfer layer include acrylic resins represented by polystyrene and polymethyl methacrylate, polycarbonate having bisphenol A and Z skeleton, polyarylate, polyphenylene ether, polyether sulfone, polyamide, polyimide, and the like. A polyester resin or the like can be used.

In the charge transfer layer, 100 parts by weight of the charge transfer material (the stilbene compound) is used, and
To 400 parts by weight. The thickness of the charge transfer layer is preferably from 5 to 100 μm.

In the electrophotographic photoreceptor of the present invention, a well-known plasticizer may be used in order to improve the film-forming property, flexibility and mechanical strength.

Further, in the electrophotographic photoreceptor of the present invention, when the phthalocyanine pigment is used in a mixture with a binder, the phthalocyanine pigment is dispersed in a solvent, and the binder and the charge transfer material (the stilbene compound) are dissolved and used. Solvents used are halogenated hydrocarbons such as chloroform, dichloromethane, dichloroethane, trichloroethane, and trichloroethylene; aromatic hydrocarbons such as benzene, toluene, and xylene; ethers such as dioxane, tetrahydrofuran, and dimethoxyethane; acetone, methyl ethyl ketone, and methyl. Solvents such as ketones such as isobutyl ketone, and cellosolves such as methyl cellosolve, dimethyl cellosolve, and methyl cellosolve acetate, or a mixture of two or more solvents, or N is an alcohol, acetonitrile, N, N-dimethylformamide, if necessary. Such a solvent can be further used. When coating on the drum, a dipping coating method or the like is used.

[0064]

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

Example 1 Metal-free phthalocyanine (Fastage manufactured by Dainippon Ink and Chemicals, Inc.)
n Blue 8120) and 1 part by weight of a polyester resin (Vylon 220 manufactured by Toyobo) were mixed with 100 parts by weight of cyclohexanone, and dispersed together with glass beads for 2 hours using a paint conditioner. The pigment dispersion thus obtained is applied on an aluminum-evaporated polyester film by an applicator and dried to obtain a film having a thickness of about 0.1.
A 2 μm charge generating material coating was formed.

Next, a stilbene compound represented by Exemplified Compound 3 is mixed with a polycarbonate resin (Panlite C-1400 manufactured by Teijin Chemicals) at a weight ratio of 1: 1 to prepare a 10% solution using dichloromethane as a solvent. This solution was applied on the above-mentioned film of the charge generating substance by an applicator to form a charge transport layer having a dry film thickness of 20 μm, thereby preparing a photoreceptor.

The laminated electrophotographic photoreceptor thus prepared is stored in a dark place at room temperature for 24 hours, and then is stuck on a drum drum made of aluminum, and a drum photoreceptor evaluation apparatus (Cynthia 90 manufactured by GenTech Co., Ltd.) Was used to evaluate the sensitivity characteristics. The measurement was performed under the conditions of a corona applied voltage of -5.2 kV, an irradiation light wavelength of 750 nm, and a power of 2.0 μW / cm ² , and the exposure was performed 5 seconds after charging. As a result, a half-exposure dose of 0.62 μJ / cm ^2, which was a very high sensitivity value, was exhibited.

Next, the same apparatus was used to evaluate the repetition characteristics of charging exposure. The measurement was performed with a corona applied voltage of -5.2 kV,
The charging and the light elimination were repeated 5000 times at a process speed of 160 mm / sec. Light elimination was performed using a tungsten lamp array. As a result, the first charging potential was −714 V, while the 5000th charging potential was −702.
V, and it was found that the electric potential was stable with little decrease in potential due to repetition. After 5,000 repetitions, the sensitivity characteristics were evaluated in the same manner as described above.
It was 1 μJ / cm ² , showing excellent characteristics without a decrease in sensitivity.

Examples 2 to 4 and Comparative Examples 1 to 4 In place of the exemplified stilbene compound 3 as the charge transfer material, the exemplified compounds shown in Table 1 and the comparative compound 37,
A laminated photoreceptor was prepared in the same manner as in Example 1 except that Chemical Formulas 38, 39 and 40 were used, and under the same measurement conditions as in Example 1,
The repetition characteristics of the photoreceptor and the sensitivity characteristics before and after that were evaluated. Table 2 shows the results.

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[Table 1]

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[Table 2]

Examples 5 to 7 and Comparative Examples 5 to 8 Examples of charge generation materials using oxytitanium phthalocyanine instead of metal-free phthalocyanine, and examples of charge transfer materials Instead of stilbene compound 3, the examples shown in Table 3 are used. Compounds and Comparative Compounds 37, 38, 3
A laminated photoreceptor was prepared in the same manner as in Example 1 except that Chemical Formulas 9 and 40 were used, and the repetition characteristics of the photoreceptor and the sensitivity characteristics before and after the same were evaluated under the same measurement conditions as in Example 1. Table 4 shows the results.

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[Table 3]

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[Table 4]

Examples 8 to 10 and Comparative Examples 9 to 12 Instead of metal-free phthalocyanine as a charge-generating material, copper phthalocyanine was used. , And Comparative Compounds 37, 38, 39, and 40, except that a laminated photoreceptor was prepared in the same manner as in Example 1 and the irradiation light wavelength at the time of measuring the sensitivity characteristics was 700 nm.
Under the same measurement conditions as in Example 1, the repetition characteristics of the photoconductor and the sensitivity characteristics before and after the evaluation were evaluated. Table 6 shows the results.

[0080]

[Table 5]

[0081]

[Table 6]

Examples 11 to 13 and Comparative Examples 13 to 16 As a charge generating substance, diphenoxygermanium phthalocyanine was used in place of metal-free phthalocyanine. A laminated photoreceptor was prepared in the same manner as in Example 1 except that Exemplified Compound and Comparative Compounds 37, 38, 39, and 40 were used.
Except for 25 nm, under the same measurement conditions as in Example 1,
The repetition characteristics of the photoreceptor and the sensitivity characteristics before and after that were evaluated. Table 8 shows the results.

[0083]

[Table 7]

[0084]

[Table 8]

[0085]

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

Claims (1)

(57) [Claims] 1. An electrophotographic photoreceptor comprising a photosensitive layer provided on a conductive support, wherein the photosensitive layer contains a phthalocyanine pigment as a charge generating substance and is represented by the following general formula 1 as a charge transfer substance. An electrophotographic photoreceptor comprising a stilbene compound. Embedded image (In the formula 1, Ar represents an aryl group which may have a substituent, and R ₁ and R ₂ each represent an alkyl group, an aralkyl group, an aryl group or a heterocyclic group which may have a substituent. , R
₃ represents a hydrogen atom or a lower alkyl group, and R ₄ , R ₅ ,
And R ₆ represent a hydrogen atom or an optionally substituted alkyl group, an aryl group, or a heterocyclic group, and R ₇ , R ₈ , and R ₉ represent a hydrogen atom, a halogen atom, or a lower alkyl group . )