JPH0659462A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To ensure excellent stability to temp. and humidity and high electrification ability and to prevent the lowering of photosensitivity even after repeated use by incorporating fine silicon oxide particles into an electric charge generating layer. CONSTITUTION:An electric charge generating layer contg. fine silicon oxide particles and an electric charge transferring layer are laminated on an electric conductive substrate. The compsn. of the silicon oxide is SiO2, the crystal system may be any crystal system and the silicon oxide may be amorphous. Silicon oxide subjected to various treatments so as to improve compatibility with an electric charge generating material, a binder and a solvent may be used. The particle diameter of the silicon oxide is preferably regulated to <=1mum average particle diameter in consideration of film forming property, dispersibility and influence on image quality. The pref. amt. of the fine silicon oxide particles added is 1-100wt.% of the amt. of the electric charge generating material.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a function-separated type electrophotographic photoreceptor in which a charge generation layer and a charge transport layer are laminated on a conductive support.

[0002]

2. Description of the Related Art Conventionally, in electrophotographic technology, inorganic materials such as selenium, cadmium sulfide, amorphous silicon, and zinc oxide have been widely used in the photosensitive layer of electrophotographic photoreceptors. Many studies have been conducted on the use of a conductive material as an electrophotographic photoreceptor.

Here, the basic properties required for an electrophotographic photoreceptor are as follows: 1) High chargeability due to corona discharge in a dark place. 2) The obtained electric charge due to corona discharge is less attenuated in a dark place. 3) Charge should be rapidly dissipated by light irradiation. 4) The residual charge after light irradiation is small. 5) Increase in residual potential and decrease in initial potential due to repeated use should not occur. 6) There are few changes in electrophotographic characteristics due to temperature and humidity.

Although the conventional inorganic electrophotographic photoreceptors such as selenium and cadmium sulfide have the requirements as a photoreceptor in terms of basic properties, they are problematic in production, for example, have strong toxicity and film formability. Is difficult, there is not much plasticity,
It has drawbacks such as high manufacturing cost. Further, in the future, due to exhaustion of resources, it is desired to use a photoconductor made of an inorganic substance instead of an organic substance instead of these inorganic substances which are limited in production and in terms of pollution due to toxicity.

In view of these points, research on electrophotographic photoreceptors made of organic substances has been actively conducted in recent years, and as a result, electrophotographic photoreceptors using various organic substances have been proposed and put to practical use. Some have. In particular, from a layer containing a substance (charge generating layer) that generates a charge carrier when irradiated with light in recent years, and a layer (charge transporting layer) containing a substance that receives the charge carrier generated by the charge generating layer and transports it. Since the proposed function-separated photoconductor for electrophotography has been shown to have excellent sensitization property and variety of material selection, research on various charge generating substances and charge transporting substances has been actively conducted. . As a result, the photosensitivity of the electrophotographic photoconductor using the organic substance has been dramatically improved, and at present, several electrophotographic photoconductors using inorganic substances have been proposed.

However, the durability of the electrophotographic photosensitive member made of an organic material having many advantages is also high in the durability of the electrophotographic photosensitive member (a-Si, As ₂ S) made of an inorganic material.
Compared with e ₂ ), no one satisfying sufficient characteristics has yet been obtained, and further higher durability is required.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide an electrophotographic photoreceptor having high sensitivity and high durability. In particular, it is an object of the present invention to provide a photoreceptor having excellent stability against temperature and humidity, high chargeability, and almost no deterioration in photosensitivity even after repeated use.

[0008]

The inventors of the present invention have conducted earnest research on a high-sensitivity and high-durability electrophotographic photoreceptor from the above viewpoints, and as a result, contain silicon oxide fine particles in the charge generation layer. As a result, they have found that they are effective in preventing the decrease in photosensitivity due to repeated use without lowering the high sensitivity, and have reached the present invention.

The composition of silicon oxide used in the present invention is SiO 2.
₂ , the crystal system thereof may be any of crystal systems such as quartz type, tridymite type, cristovite type, stishovite, silica C and silica K, and further, amorphous (amorphous) type. I don't care. Further, in consideration of compatibility with the charge generating substance, the binder and the solvent, silicon oxide which is provided with a hydrophilic or hydrophobic surface coating or subjected to various treatments is also included. Regarding the particle diameter, it is necessary to set the average particle diameter to 1 μm or less, preferably 0.2 μm or less as a result of studying the influence on the film forming property, dispersibility and image quality. The amount of the silicon oxide fine particles added is preferably in the range of 1% by weight to 100% by weight with respect to the charge generating substance, and when the amount is 1% by weight or less, the addition effect does not appear. Deterioration of electrophotographic characteristics such as charging property is remarkable.

As a method of adding to the charge generating layer, there are a method of dispersing the silicon oxide fine particles, the charge generating substance and, if necessary, a binder resin in a solvent. The resulting dispersion is applied and dried. As a result, the charge generation layer according to the present invention is obtained. Examples of the charge generating substance used here include phthalocyanine-based pigments such as various metal phthalocyanines, metal-free phthalocyanines, and halogen-free metal-free phthalocyanines, perylene-based pigments such as perylene imide and perylene anhydride, bisazo-based pigments, and azo such as trisazo-based pigments. -Based pigments, other quinacridone-based pigments, anthraquinone-based pigments, and triphenylmethane-based dyes represented by methyl violet, crystal violet, night blue, Victoria blue, etc., represented by erythrosine, rhodamine B, rhodamine 3R, acridine orange, frapeocine, etc. Acridine dyes, thiazine dyes represented by methylene blue, methylene green, etc., oxazine dyes represented by capri blue, Meldola blue, etc.
Other examples include cyanine dyes, styryl dyes, pyrylium salt dyes, and thiopyrylium salt dyes. These may be used alone or in combination of two or more, if necessary.

As the binder resin, polystyrene resin, polyvinyl acetal resin, polysulfone resin, polycarbonate resin, polyphenylene oxide resin, polyester resin, alkyd resin, polyarylate resin, acrylic resin, silicone resin, polyamide resin and the like are preferable. You may use these individually or in mixture of 2 or more types.

The charge transport layer is electrically connected to the charge generation layer and has a function of transporting charge carriers injected from the charge generation layer in the presence of an electric field. Materials for such a charge transport layer are generally classified into substances that transport electrons and substances that transport holes, but both can be used in the photosensitive layer of the present invention, and a mixture thereof can also be used. You can As a substance that transports electrons,
Substances having an electron-withdrawing group such as nitro group and cyano group, for example, 2,4,7-trinitro-9-fluorenone,
Examples include nitrated fluorenone such as 2,4,5,7-tetranitro-9-fluorenone and trinitrotoluene. In addition, as a substance that transports holes, an electron-donating substance, for example, a heterocyclic compound such as carbazole, oxazole, thiazole, oxadiazole, imidazole, or pyrazoline, or a low-molecular compound such as an aniline derivative, an arylamine derivative, or a hydrazone derivative is used. Molecular charge transport materials, poly-N-vinylcarbazole, halogenated poly-
Polymeric charge transport substances such as N-vinylcarbazole, polyvinylpyrene, polyvinylanthracene and the like can be used. However, the charge transport material used in the present invention is not limited to these. The charge transport material may be used alone or in combination of two or more.

When a low molecular weight charge transporting substance is used, a film can be formed by selecting an appropriate binder resin, but a polymer charge transporting substance having film forming property can also be used. Moreover, you may mix the said polymeric charge transport material in a binder resin. The binder resin used here may be the same as that used for the charge generation layer.

The electrophotographic photoreceptor of the present invention can be obtained by applying the dispersion / solution of the charge-generating layer and the charge-transporting layer described above onto a conductive support and drying. The conductive support, the base itself has conductivity,
For example, aluminum, aluminum alloys, copper, zinc,
In addition to stainless steel, nickel, chrome, titanium, etc., other materials such as aluminum, aluminum alloy, indium oxide, tin oxide, etc., which have a layer formed by vacuum deposition, and conductive particles are impregnated in plastic, paper, etc. A substrate, a plastic having a conductive polymer, or the like can be used.

As the coating solvent, benzene, toluene,
Aromatic hydrocarbons such as xylene and monochlorobenzene,
Solvents such as dioxane, dimethoxymethyl ether, dimethylformamide and the like, or a mixed solvent of two or more kinds thereof, or, if necessary, solvents such as alcohols, acetonitrile and methyl ethyl ketone can be further used.

Further, the photosensitive layer of the electrophotographic photosensitive member of the present invention comprises one or more electron-accepting substances for the purpose of improving sensitivity, suppressing increase in residual potential during repeated use and suppressing fatigue. Or a pigment may be contained. Examples of the electron-accepting substance used here include acid anhydrides such as succinic anhydride, maleic anhydride, phthalic anhydride, and 4-chloronaphthalic anhydride, and cyano compounds such as tetracyanoethylene and terephthalmalondinitrile. -Aldehydes such as nitrobenzaldehyde, anthraquinones, anthraquinones such as 1-nitroanthraquinone, 2,4,7-
A polycyclic or heterocyclic nitro compound such as trinitrofluorenone and 2,4,5,7-tetranitrofluorenone can be used as the chemical sensitizer.

As the dye, for example, an organic photoconductive compound such as a xanthene-based dye, a thiazine dye, a triphenylmethane dye, a quinoline-based pigment or a copper phthalocyanine pigment can be used as an optical sensitizer. Further, the photosensitive layer of the electrophotographic photosensitive member of the present invention may contain a known plasticizer in order to improve moldability, flexibility and mechanical strength. Examples of the plasticizer include dibasic acid ester, fatty acid ester, phosphoric acid ester, phthalic acid ester, chlorinated paraffin, and epoxy type plasticizer. Moreover, you may contain a leveling agent, antioxidant, a ultraviolet absorber, etc. as needed.

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

[0019]

【Example】

Example 1 An aluminum vapor-deposited polyester film (having a thickness of 80 μm) was used as a conductive support, and the following structural formula (I) was provided thereon.

[0020]

[Chemical 1]

1 part by weight of the bisazo pigment represented by the formula, 0.25 part by weight of amorphous silicon oxide fine particles having an average particle size of 0.01 to 0.02 μm, and 1 part by weight of polyvinyl butyral resin (manufactured by Nissin Chemical Industry Co., Ltd., S-REC B). Part and THF9
8 parts by weight were dispersed together with glass beads having a diameter of 1.5 mm in a paint shaker (manufactured by Red Revel Co.) for about 2 hours, coated with a baker applicator and dried. The film thickness after drying was 0.2 μm.

On the charge generation layer, the following structural formula (II)

[0023]

[Chemical 2]

1 part by weight of a hydrazone compound represented by
1 part by weight of polyarylate resin and 8 parts by weight of methylene chloride were mixed, stirred and dissolved, and applied by a baker applicator and dried by heating to form a charge transport layer having a thickness of 20 μm. The laminated electrophotographic photosensitive member thus prepared was used as an electrostatic recording paper tester (Kawaguchi Denki; SP-42).
The electrophotographic characteristics were evaluated according to 8).

The measurement conditions were as follows: applied voltage: -6 kV, static: No. 3 is white light irradiation (irradiation light: 5lux)
The exposure amount E ₁₀₀ (lux seconds) required to attenuate from −700 V to −100 V and the initial potential V ₀ (−volt) were measured, and the values are shown in Table 1. Further, using the same device, the initial potential V ₀ (−volt) and E after performing the same operation 10,000 times with charge-elimination (charge elimination light: irradiation with white light at 40 lux for 1 second) as one cycle ₁₀₀ (lux · sec) was measured, and changes in V ₀ and E ₁₀₀ were examined. The results are shown in Table 1.

Examples 2, 3, 4, 5 In Example 1, instead of the amorphous silicon oxide fine particles, quartz type silicon oxide fine particles (average particle size 0.1 to 0.
2 μm) 0.5 part by weight, or tridymite type silicon oxide fine particles (average particle size 0.05 to 0.1 μm) 0.1 part by weight, or critobalite type silicon oxide fine particles (average particle size 0.02 to 0.05 μm) Example 2 was repeated in the same manner as Example 1 except that 0.25 part by weight or 0.5 part by weight of silica K (average particle size 0.1 to 0.2 μm) was used.
Tables 1 and 3 show the results of the measurement of the electrophotographic photosensitive members 3, 4, and 5 prepared.

Comparative Examples 1 and 2 For electrophotography of Comparative Examples 1 and 2 in the same manner as in Example 1 except that amorphous silicon oxide was not used or the addition amount was increased to 2 parts by weight. Table 1 shows the results of measurement and measurement of the photoconductor.

[0028]

[Table 1]

Examples 6 and 7 In Example 1, the following structural formula (III) was used instead of the azo pigment represented by the structural formula (I).

[0030]

[Chemical 3]

The polycyclic quinone pigment shown by or the following structural formula (IV)

[0032]

[Chemical 4]

Electrophotographic photoconductors of Examples 6 and 7 were prepared in the same manner as in Example 1 except that the phthalocyanine pigment shown in was used. The electrophotographic characteristics were measured in the same manner as in Example 1, and the results are shown in Table 2.

Comparative Examples 3 and 4 Electrophotographic photosensitive members of Comparative Examples 3 and 4 were prepared and measured in the same manner as in Example 1 except that amorphous silicon oxide was not used. The results are shown in Table 2.

Comparative Example 5 An electrophotographic photoreceptor was prepared in the same manner as in Example 1 except that the amorphous silicon oxide fine particles had an average particle size of 1 μm to 2 μm. Since the dispersibility was very poor and the charge generation layer had a rough surface, the image quality was evaluated by mounting it on an actual copying machine and found an image with remarkable roughness.

[0036]

[Table 2]

From the results shown in Tables 1 and 2, it was found that the electrophotographic photosensitive member according to the present invention showed almost no deterioration in sensitivity due to repeated use and was extremely excellent in durability.

[0038]

INDUSTRIAL APPLICABILITY In the present invention, the inclusion of silicon oxide fine particles in the charge generation layer has no adverse effect on the film-forming property, film strength, image quality and electrophotographic properties of the function-separated electrophotographic photoreceptor. Therefore, it is possible to prevent the deterioration of the photosensitivity when it is repeatedly used, and it is possible to obtain the electrophotographic photoreceptor having high sensitivity and high durability.

Front page continued (72) Inventor Kazumi Morita 22-22 Nagaike-cho, Abeno-ku, Osaka-shi, Osaka Within Sharp Corporation (72) Inventor Satoshi Nishigaki 22-22 Nagaike-cho, Abeno-ku, Osaka, Osaka Sharp, Inc. (72) Inventor Kazuhiro Enomoto 22-22 Nagaike-cho, Abeno-ku, Osaka-shi, Osaka Prefecture

Claims (3)

[Claims] 1. A function-separated electrophotographic photosensitive member comprising a conductive support and a charge generation layer and a charge transport layer laminated on the conductive support, wherein the charge generation layer contains fine particles of silicon oxide. Electrophotographic photoreceptor. 2. The average particle diameter of the silicon oxide fine particles is 1
The electrophotographic photosensitive member according to claim 1, wherein the electrophotographic photosensitive member has a thickness of not more than μm. 3. The electrophotographic photoreceptor according to claim 1, wherein the content of the silicon oxide fine particles is 1% by weight to 100% by weight based on the charge generating substance.