JP2002221808A - Positively chargeable monolayer organic photoreceptor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a positively chargeable monolayer organic photoreceptor having a long service life and high sensitivity and less liable to cause image defects. SOLUTION: In the positively chargeable monolayer organic photoreceptor with a monolayer type photosensitive layer containing metal oxide fine particles based on titanium dioxide or tin oxide, the photosensitive layer contains the metal oxide fine particles having <=50 nm average primary particle diameter and an electron transporting material of formula (1) or (2).

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 used in an electrophotographic printer, a copying machine, and the like, and more particularly, to a positively charged single-layer organic photosensitive member having good image quality even in repeated use. Things.

[0002]

2. Description of the Related Art Conventionally, as an electrophotographic photoreceptor, an inorganic photoreceptor having an inorganic photoconductive material such as selenium or a selenium alloy, zinc oxide, cadmium sulfide or the like as a main photosensitive layer material has been widely used.

However, in recent years, various types of organic photoconductive materials can be used as a photosensitive layer material because it is possible to prevent pollution and environmental pollution, which are problems in inorganic photoreceptors, and to adopt a coating method which is advantageous in terms of manufacturing cost. Research and development of organic photoreceptors having them have been actively conducted and put to practical use.

[0004] Recently, in order to satisfy performances such as sensitivity and durability, a charge-generating layer containing a charge-generating substance and a charge-transporting layer containing a charge-transporting substance are laminated on a support in this order as a photosensitive layer. Separated and stacked photoreceptors are the mainstream, and among them, a layer in which an organic pigment is dispersed in a resin as a charge generating substance or a vapor-deposited layer of an organic pigment is used as a charge generating layer, and a charge transporting substance composed of an organic low-molecular compound is used as a resin. Many functionally separated organic photoreceptors using a layer dispersed therein as a charge transport layer have been proposed.

[0005] In such a laminated organic photoreceptor, since there is no high-performance charge transporting substance for transferring electrons, the charge transporting layer is placed on the upper side in consideration of durability as described above. The structure becomes a negative charging type. The negative charging type photoreceptor has a problem that a system for uniformly charging is required and a large amount of ozone is generated to deteriorate environmental conditions.

In order to solve this problem, various positively-chargeable organic photoconductors have been proposed. In the case of negative charging type,
From the well-known organic charge transporting materials having excellent hole transporting ability, the most suitable one can be adopted as appropriate, whereas in the case of the positive charging type, an organic material having excellent electron transporting ability is used. However, many of them have comparatively good performance and also have toxicity or carcinogenicity, and their practical use has been delayed.

As such an electron transporting substance, several organic compounds having a soluble group introduced into the electron accepting structure of a molecule have been proposed in recent years. Known documents that describe such an electron transport material include JP-A-Heisei 1-2063.
49, JP-A-3-290666, JP-A-4
-360148, JP-A-5-92936,
JP-A-5-279852, JP-A-7-17977
No. 5, JP-A-9-151157, JP-A-9-151157
Patent gazettes such as Japanese Patent Application Publication No. 0-73937 and the Journal of the Institute of Electrophotography, Vol. 30, No. 3, p.
4-281 (1991) and “Japan Hard
Copy '92' Papers July 6, 7 and 8, 1992 JA Hall (Otemachi, Tokyo) p173-17
6, “Japan Hard Copy '97”, July 9, 10 and 11, 1997 JA Hall (Otemachi, Tokyo) p21-24, or “Pan-
Pacific Imaging Conference
e / Japan HardCopy '98 ”Proceedings
July 15-17, 1998 JA HALL, To
General scientific and technical literature such as kyo, Japan p207-210 can be mentioned.

However, in any of the above compounds, sensitivity and electric characteristics are not sufficient in combination with an existing charge generating substance, and at present, it must be said that they have practical problems.

[0009] In order to separate the function of the positively charged photosensitive layer like the charge generation layer and the charge transport layer, there is no electron transporting material as described above. A charge transport layer containing a hole transport material must be provided, and a thin-film charge generation layer must be provided thereon. In this case, it is necessary to further cover with a surface protective layer in order to protect the charge generating layer of the thin film. However, the provision of a surface protective layer causes new problems such as a difficulty in designing a photosensitive layer because of a decrease in sensitivity characteristics, and an increase in the number of coatings due to an increase in the number of laminations, thereby increasing manufacturing costs. appear.

In order to solve these problems, a single-layer type organic photoreceptor in which a charge generating substance and a charge transporting substance are dispersed in a single film, and a composite type in which a charge transporting layer is further provided under the single-layer type organic photoreceptor. Has been proposed. However, such a positively charged organic photoreceptor is not always at a level that sufficiently satisfies the required characteristics required for the photoreceptor.

In recent years, with the networking and the increase in the amount of information in office printers, there is an increasing demand for extending the life of photoconductors. To cope with this, it is necessary to further reduce the thickness reduction of the photoreceptor, but the conventional constituent materials have limitations and measures have been desired.

For example, as one means for improving the electron transport ability and printing durability, there is a method in which an n-type semiconductor such as titanium oxide is dispersed in a photosensitive layer. This is disclosed in Japanese Unexamined Patent Publication No. 7-2
No. 61413.

However, the electron transport ability of titanium oxide fine particles as an n-type semiconductor cannot be said to be at a practical level necessary and sufficient in a single-layer type photosensitive layer. In addition, in the production technology of the photosensitive layer, particularly when the particle size of titanium oxide is large, there is a problem that the dispersion in the coating solution is not stable and the fine particles settle if left for a long period of time. Further, even if the primary particle size of the particles in the actual photosensitive layer is so small as to be invisible, the particles are aggregated in the coating solution and the particle size grows so that the particles can be visually observed (particle size of 0.1 mm or more). Sometimes.
When a photosensitive layer containing these agglomerated particles is formed by coating, a problem often occurs that the agglomerated particles are peeled off from the photosensitive layer and the fallen particles damage the photosensitive layer. In particular, in the case of a single-layer type photoreceptor, since the charge generation region is on the photosensitive layer surface side, the effect of the image due to surface defects is greater than that of the stacked type in which the charge generation region is on the lower side, which is a major obstacle in practical use. ing.

[0014]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to provide a positively charged single-layer type photoreceptor having a long life, high sensitivity, and few image defects. An object of the present invention is to provide a charged single-layer organic photoreceptor.

[0015]

According to the first aspect of the present invention, there is provided a positively-charged photosensitive layer having a single-layer type photosensitive layer containing metal oxide fine particles containing titanium oxide or tin oxide as a main component. In the organic photoreceptor, the photosensitive layer is a positively charged single-layer type containing the metal oxide fine particles having an average primary particle diameter of 50 nm or less and an electron transport material represented by the following chemical structural formula (1) or (2). By using an organic photoreceptor,
Achieved. (A and B are each an atomic group that satisfies the valency shown in the following chemical structural formula, and formula (2) includes the case where there is no B. R ¹ to R ⁶ are each an H atom or the number of C (carbon). Is an alkyl group of 1 to 4, X ¹ to X ³
Represents an H atom or a halogen atom, respectively. )

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According to the second aspect of the present invention, the metal oxide fine particles are desirably titanium oxide.

According to the third aspect of the invention, the metal oxide fine particles are preferably made of indium tin oxide (ITO).

According to the fourth aspect of the present invention, the metal oxide fine particles are preferably made of antimony tin oxide (ATO).

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An overall embodiment of a positively charged single-layer type organic photoreceptor of the present invention will be described with reference to the drawings.

(Layer Structure) FIG. 1 is a conceptual sectional view showing an embodiment of a positively charged single-layer type organic photoreceptor according to the present invention, wherein 1 is a conductive support, 2 is an intermediate layer, 3 is a photosensitive layer, Reference numeral 4 denotes a protective layer, and an intermediate layer and a protective layer are provided as needed. The photosensitive layer 3 has a charge generation function and a charge transport function, and is a single-layer photosensitive layer having both functions in one layer. The metal oxide fine particles according to the present invention are uniformly dispersed in the photosensitive layer 3.

(Conductive Support) The conductive support 1 serves as an electrode of the photoreceptor and serves as a support for the other layers, and may be any of a cylinder, a plate, and a film.
Aluminum is the most commonly used material,
Metals such as stainless steel and nickel, or glass,
A conductive material may be applied to a resin or the like.

(Intermediate Layer) The intermediate layer 2 is made of a layer mainly composed of a resin or an oxide film such as alumite, prevents injection of unnecessary charges from the conductive support to the photosensitive layer, and covers defects on the surface of the support. It is provided as needed for the purpose of improving the adhesiveness between the conductive support and the photosensitive layer.

In the present invention, the binder resin used for the intermediate layer may be a copolymer of vinyl chloride, vinyl acetate and other resin components, or a polycarbonate resin, a polyester resin, a polyvinyl acetal resin, a polyvinyl butyral resin, a polyvinyl alcohol. Resin, vinyl chloride resin, vinyl acetate resin, polyethylene, polypropylene, polystyrene, acrylic resin, polyurethane resin,
Epoxy resin, melamine resin, silicone resin, polyamide resin, polystyrene resin, polyacetal resin, polyarylate resin, polysulfone resin, methacrylic acid ester polymer and their copolymers are used singly or in combination of two or more. It is possible to

Further, the intermediate layer in the present invention may contain titanium oxide as metal oxide fine particles, and may include silicon oxide (silica), zinc oxide, calcium oxide, aluminum oxide (alumina), and zirconium oxide. And metal sulfates such as barium sulfate and calcium sulfate, and fine particles of metal nitride such as silicon nitride and aluminum nitride. These contents can be arbitrarily set as long as a layer can be formed.

In the case of an intermediate layer containing a binder resin as a main component, for the purpose of imparting hole transporting ability and reducing charge trapping,
A hole transport material can be included. The content of the hole transport material is 0.1 to 60% by weight, preferably 5 to 40% by weight, based on the solid content of the intermediate layer.

Further, if necessary, other known additives can be contained as long as the electrophotographic properties are not significantly impaired.

These intermediate layers may be used as a single layer, but two or more layers of different types may be laminated and used.

Although the thickness of the intermediate layer depends on the material composition of the intermediate layer, it can be arbitrarily set within a range where adverse effects such as an increase in residual potential do not occur when used repeatedly and continuously.

(Photosensitive Layer) The photosensitive layer 3 has a single-layer structure mainly composed of a charge generating substance, a hole transporting substance, an electron transporting substance (acceptor compound), and a binder resin.

The charge-generating substance is not particularly limited. For example, phthalocyanine pigments, azo pigments, anthantrone pigments, perylene pigments, perinone pigments, polycyclic quinone pigments, squarylium pigments, thiapyrylium pigments, quinacridone pigments and the like are used. These charge generating substances can be used alone or in combination of two or more. Particularly, in the positively charged single-layer type organic photoreceptor of the present invention, disazo pigments, trisazo pigments and N, N'-bis (3,5
-Dimethylphenyl) -3,4,9,10-perylene-
As bis (carboximide) and phthalocyanine pigments, metal-free phthalocyanine, copper phthalocyanine, and titanyl phthalocyanine are preferable, and further, X-type metal-free phthalocyanine, τ-type metal-free phthalocyanine, ε-type copper phthalocyanine, α-type titanyl phthalocyanine, β -Type titanyl phthalocyanine, Y-type titanyl phthalocyanine, amorphous titanyl phthalocyanine, JP-A-8-209
The use of titanyl phthalocyanine having a Bragg angle 2θ of 9.6 ° as the maximum peak in the CuKα: X-ray diffraction spectrum described in Japanese Patent No. 023 shows a markedly improved effect in terms of sensitivity, durability and image quality. The content of the charge generating substance is 0.1 to 20% by weight based on the solid content of the photosensitive layer.
Preferably, it is 0.5 to 10% by weight.

The hole transporting substance is not particularly restricted but includes, for example, hydrazone compounds, pyrazoline compounds, pyrazolone compounds, oxadiazole compounds, oxazole compounds, arylamine compounds, benzidine compounds, stilbene compounds, styryl compounds, poly-N -Vinyl carbazole, polysilane and the like can be used, and these hole transport substances can be used alone or in combination of two or more. As the hole transporting substance used in the present invention, those having excellent transporting ability of holes generated upon light irradiation and suitable for combination with a charge generating substance are preferable. The content of the hole transporting substance is 5 to 80% by weight, preferably 10 to 6% by weight, based on the solid content of the photosensitive layer.
0% by weight.

Specific examples of the electron transporting substance belonging to the chemical structural formulas (1) and (2) according to the present invention are shown below.

[0033]

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[0034]

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In addition, succinic anhydride, maleic anhydride,
Dibromo succinic anhydride, phthalic anhydride, 3-nitrophthalic anhydride, 4-nitrophthalic anhydride, pyromellitic anhydride, pyromellitic acid, trimellitic acid, trimellitic anhydride, phthalimide, 4-nitrophthalimide, tetracyano Ethylene, tetracyanoquinodimethane, chloranil, bromanyl, o-nitrobenzoic acid, malononitrile, trinitrofluorenone, trinitrothioxanthone, dinitrobenzene, dinitroanthracene, dinitroacridine, nitroanthraquinone, dinitroanthraquinone, thiopyran-based compounds, quinone-based compounds Electron transport materials (acceptor compounds) such as benzoquinone compounds, diphenoquinone compounds, naphthoquinone compounds, anthraquinone compounds, stilbenequinone compounds, and azoquinone compounds Combination can be used. The content of the electron transporting substance is 1 to 50% by weight, preferably 5 to 40% by weight based on the solid content of the photosensitive layer.
It is.

As the binder resin, a polycarbonate resin alone or a polyester resin, polyvinyl acetal resin, polyvinyl butyral resin, polyvinyl alcohol resin, vinyl chloride resin, vinyl acetate resin, polyethylene, polypropylene, polystyrene, acrylic resin, polyurethane resin , Epoxy resin, melamine resin,
Silicone resin, polyamide resin, polystyrene resin,
It can be used in combination with a resin such as a polyacetal resin, a polyarylate resin, a polysulfone resin, a polymer of methacrylic acid ester, and a copolymer thereof. Further, resins of the same type having different molecular weights may be mixed and used. The content of the binder resin is 10 to 90% by weight, and preferably 20 to 80% by weight, based on the solid content of the photosensitive layer, and the proportion of the polycarbonate resin in the binder resin is 1% by weight. To 100% by weight, more preferably 20% to 80% by weight.

Furthermore, in addition to the metal oxide fine particles of the present invention, silicon oxide (silica), zinc oxide, calcium oxide, aluminum oxide (alumina), zirconium oxide, etc. Metal oxides such as barium sulfate, calcium sulfate and the like, metal nitride fine particles such as silicon nitride and aluminum nitride, or fluorine resin particles such as tetrafluoroethylene resin, and fluorine-based comb-type graft polymer resin And the like.

The thickness of the photosensitive layer is preferably in the range of 3 to 100 μm, more preferably 10 to 50 μm, in order to maintain a practically effective surface potential.

For the purpose of improving environmental resistance and stability against harmful light, these photosensitive layers may contain a deterioration inhibitor such as an antioxidant or a light stabilizer. Compounds used for such purposes include chromanol derivatives and esterified compounds such as tocopherol, polyarylalkane compounds, hydroquinone derivatives, etherified compounds, dietherified compounds, benzophenone derivatives, benzotriazole derivatives, thioether compounds, phenylenediamine derivatives , Phosphonate esters, phosphite esters, phenol compounds, hindered phenol compounds, linear amine compounds, cyclic amine compounds, hindered amine compounds, and the like.

The photosensitive layer may contain a leveling agent such as silicone oil or fluorine-based oil for the purpose of improving the leveling property of the formed film and imparting lubricity.

Further, if necessary, other known additives can be contained within a range that does not significantly impair the electrophotographic properties.

In the present invention, the purpose of containing the metal oxide fine particles in the photosensitive layer is to suppress the film loss of the photosensitive layer by containing the metal oxide fine particles having high hardness, and at the same time, to use the metal oxide fine particles. Has no n-type semiconductor characteristics, so that it does not trap charges, and in particular, when combined with a quinone-based electron transporting agent, a remarkable improvement in sensitivity is observed. However, as described above, the fine particles themselves have no practical electron transporting ability, and coexistence of a specific electron transporting material is indispensable for the present invention.

The metal oxide fine particles are not only transparent to light near a wavelength of 800 nm of a laser diode usually used for a laser printer, but also
The average primary particle size is 50 nm or less, and the
Since it is much smaller than 0 nm, there is no scattering of light, and the use efficiency of incident light is not reduced.

Further, by limiting the average primary particle size to 50 nm or less, even if the particles are agglomerated in the coating solution, the particles do not grow to a size that accelerates the sedimentation. The performance is greatly improved. Conventionally, particles may grow to a size of 0.1 mm or more due to agglomeration of the particles. In such a case, large particles of 0.1 mm or more that are separated from the photosensitive layer after the formation of the photosensitive layer may damage the photosensitive layer. However, in the present invention, as described above, since the crystal does not grow to a size of 0.1 mm or more, even if there is a scratch on the photoreceptor surface, it is minimized. In practice, this problem has been solved.

(Protective Layer) The protective layer 4 can be provided as needed for the purpose of improving printing durability and the like. The protective layer 4 is made of a layer mainly composed of a binder resin or an inorganic thin film such as amorphous carbon. Become. In the binder resin, silicon oxide (silica), titanium oxide, zinc oxide, calcium oxide, aluminum oxide (alumina), oxide Metal oxides such as zirconium, metal sulfates such as barium sulfate and calcium sulfate, metal nitride fine particles such as silicon nitride and aluminum nitride, or fluorine-based resin particles such as tetrafluoroethylene resin, fluorine-based comb-type graft polymerization It may contain a resin or the like.

For the purpose of imparting charge transporting ability, the photosensitive layer may contain a hole transporting substance and an electron transporting substance, and may be formed to improve the leveling property and impart lubricity of the formed film. A leveling agent such as silicone oil or fluorine-based oil may be contained.

Further, if necessary, other known additives can be contained within a range that does not significantly impair the electrophotographic properties.

(Forming method) When each layer of the photoreceptor is formed by coating, the above constituent materials are added together with a suitable solvent.
Dissolve and disperse by known methods such as paint shaker, ball mill, ultrasonic dispersion and the like to prepare a coating solution, and a known coating method such as dip coating, spray coating, blade coating, roll coating, spiral coating, slide hopper coating, etc. And then dried.

As a solvent for preparing the coating solution, various organic solvents can be used. The organic solvent used in the intermediate layer coating solution is not particularly limited, but is generally dimethyl ether, diethyl ether, 1,4-dioxane, tetrahydrofuran, tetrahydropyran, ethylene glycol dimethyl ether, ether solvents such as diethylene glycol dimethyl ether, It is effective to use a ketone solvent such as acetone, methyl ethyl ketone, cyclohexanone, methyl isobutyl ketone, and methyl isopropyl ketone singly or as a mixture of two or more, and it is also possible to mix with another organic solvent.

As the organic solvent used for the photosensitive layer coating solution, those which have low solubility in the intermediate layer and dissolve the material used for the photosensitive layer are preferable. In particular, it is effective to use halogenated hydrocarbons such as dichloromethane, dichloroethane, trichloroethane, chloroform, chlorobenzene and the like singly or in an appropriate combination, and it is also possible to mix with other organic solvents.

The organic solvent used in the coating solution for the protective layer is not particularly limited, but may be any as long as it does not dissolve the photosensitive layer but dissolves the organic material used for the protective layer.

In the present invention, the positively charged single-layer type organic photoreceptor is a semiconductor laser (780 nm, 680 nm, etc.), L
Exposure light sources such as ED, non-contact charging methods such as corotron and scorotron, and contact charging methods such as rollers and brushes,
Furthermore, the present invention is applied to various copiers, printers, and facsimile machines having a magnetic one-component, non-magnetic one-component, and two-component developing system, and a remarkable effect can be obtained.

[0053]

EXAMPLES The present invention will be described below in detail with reference to examples, but embodiments of the present invention are not limited to these examples. still,
In the text, “parts” represents “parts by weight” and “%” represents “% by weight”.

(Example 1) An intermediate layer and a photosensitive layer having the following compositions were sequentially formed on an aluminum cylindrical conductive support using a dip coater.

(Intermediate Layer) A film was formed using a coating solution prepared by sufficiently stirring and dissolving the following materials, and dried at 100 ° C. for 30 minutes to form an intermediate layer having a thickness of 0.2 μm. Vinyl chloride-vinyl acetate-vinyl alcohol copolymer (SOLBIN A: Nissin Chemical) (vinyl chloride 92% -vinyl acetate 3% -vinyl alcohol 5%) 50 parts Methyl ethyl ketone 950 parts

(Photosensitive layer) Among the following materials, those other than the binder resin were dispersed for 1 hour using a paint shaker, and then the binder resin was added, and the mixture was sufficiently stirred and dissolved, and further dispersed for 1 hour. A film is formed using a coating solution,
After drying for a minute, a single-layer photosensitive layer having a thickness of 25 μm was formed. Charge generating substance: X-type metal-free phthalocyanine 2 parts Hole transporting substance: 65 parts of hole transporting substance (HTM-1 below) Electron transporting substance: 28 parts of electron transporting substance (ET1-3) 28 parts Titanium oxide: P-25 ( Nippon Aerosil) (Average primary particle diameter 21 nm) 5 parts Silicone oil: KF-54 (Shin-Etsu Chemical Co., Ltd.) 0.1 parts Binder resin: Panlite TS2020: (Teijin Kasei) (the following bisphenol Z-type polycarbonate resin) 100 parts THF (Tetrahydrofuran) 1000 parts

[0057]

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Embedded image As described above, a positively charged single-layer type organic photoreceptor was prepared.

Example 2 A photoconductor was prepared in the same manner as in Example 1, except that the composition of the photosensitive layer in Example 1 was changed as follows. Charge generating substance: X-type metal-free phthalocyanine 2 parts Hole transporting substance: 65 parts of hole transporting substance (HTM-1) Electron transporting substance: 28 parts of electron transporting substance (ET1-3) 28 parts Titanium oxide: P-25 ( Nippon Aerosil) (Average primary particle size: 21 nm) 20 parts Silicone oil: KF-54 (Shin-Etsu Chemical Co., Ltd.) 0.1 parts Binder resin: Panlite TS2020: (Teijin Kasei) (The bisphenol Z-type polycarbonate resin) 85 parts THF (Tetrahydrofuran) 1000 parts

Example 3 A photoconductor was prepared in the same manner as in Example 1, except that the composition of the photosensitive layer in Example 1 was changed as follows. Charge generating substance: X-type metal-free phthalocyanine 2 parts Hole transporting substance: 65 parts of hole transporting substance (HTM-1) Electron transporting substance: 28 parts of electron transporting substance (ET2-1) 28 parts Titanium oxide: P-25 ( Nippon Aerosil) (Average primary particle size: 21 nm) 20 parts Silicone oil: KF-54 (Shin-Etsu Chemical Co., Ltd.) 0.1 parts Binder resin: Panlite TS2020: (Teijin Kasei) (The bisphenol Z-type polycarbonate resin) 85 parts THF (Tetrahydrofuran) 1000 parts

Example 4 A photoconductor was prepared in the same manner as in Example 1, except that the composition of the photosensitive layer in Example 1 was changed as follows. Charge generating substance: X-type metal-free phthalocyanine 2 parts Hole transporting substance: 65 parts of hole transporting substance (HTM-1) Electron transporting substance: 28 parts of electron transporting substance (ET1-3) 28 parts Titanium oxide: P-25 ( (Nippon Aerosil) (Average primary particle size: 21 nm) 28 parts Silicone oil: KF-54 (Shin-Etsu Chemical Co., Ltd.) 0.1 part Binder resin: Panlite TS2020: (Teijin Chemical) (The bisphenol Z-type polycarbonate resin) 77 parts THF (Tetrahydrofuran) 1000 parts

Example 5 A photoconductor was prepared in the same manner as in Example 1, except that the composition of the photosensitive layer in Example 1 was changed as follows. Charge generating substance: X-type metal-free phthalocyanine 2 parts Hole transporting substance: 65 parts of hole transporting substance (HTM-1) Electron transporting substance: 28 parts of electron transporting substance (ET1-3) 28 parts Titanium oxide: OX-50 ( Nippon Aerosil) (Average primary particle size 40 nm) 20 parts Silicone oil: KF-54 (Shin-Etsu Chemical Co., Ltd.) 0.1 parts Binder resin: Panlite TS2020: (Teijin Kasei) (The bisphenol Z-type polycarbonate resin) 85 parts THF (Tetrahydrofuran) 1000 parts

Example 6 A photoconductor was prepared in the same manner as in Example 1, except that the composition of the photosensitive layer in Example 1 was changed as follows. Charge generating substance: X-type metal-free phthalocyanine 2 parts Hole transporting substance: 65 parts of hole transporting substance (HTM-1) Electron transporting substance: 28 parts of electron transporting substance (ET1-3) 28 parts Antimony / tin oxide: ATO (Mitsui Metals) Average primary particle size (20 nm) 20 parts Silicone oil: KF-54 (Shin-Etsu Chemical Co., Ltd.) 0.1 parts Binder resin: Panlite TS2020: (Teijin Chemical) (Bisphenol Z-type polycarbonate resin) 85 parts 1000 parts of THF (tetrahydrofuran)

Example 7 A photoconductor was prepared in the same manner as in Example 1, except that the composition of the photosensitive layer in Example 1 was changed as follows. Charge generating substance: X-type metal-free phthalocyanine 2 parts Hole transporting substance: 65 parts of hole transporting substance (HTM-1) Electron transporting substance: 28 parts of electron transporting substance (ET1-3) 28 parts Indium / tin oxide: ITO (Mitsui Metals) Average primary particle size (20 nm) 20 parts Silicone oil: KF-54 (Shin-Etsu Chemical Co., Ltd.) 0.1 parts Binder resin: Panlite TS2020: (Teijin Chemical) (Bisphenol Z-type polycarbonate resin) 85 parts 1000 parts of THF (tetrahydrofuran)

Comparative Example 1 A photoconductor was prepared in the same manner as in Example 1, except that the composition of the photosensitive layer in Example 1 was changed as follows. Charge generating substance: X-type metal-free phthalocyanine 2 parts Hole transporting substance: 65 parts of hole transporting substance (HTM-1) Electron transporting substance: 28 parts of electron transporting substance (ET1-3) 28 parts Silicone oil: KF-54 ( Shin-Etsu Chemical Co., Ltd. 0.1 part Binder resin: Panlite TS2020: (Teijin Chemical) (bisphenol Z-type polycarbonate resin) 105 parts THF (tetrahydrofuran) 1000 parts

Comparative Example 2 A photoconductor was prepared in the same manner as in Example 1, except that the composition of the photosensitive layer in Example 1 was changed as follows. Charge generating substance: X-type metal-free phthalocyanine 2 parts Hole transporting substance: 65 parts of hole transporting substance (HTM-1) Titanium oxide: P-25 (Nippon Aerosil) (average primary particle size 21 nm) 28 parts Silicone oil: KF-54 (Shin-Etsu Chemical Co., Ltd.) 0.1 part Binder resin: Panlite TS2020: (Teijin Chemical) (the bisphenol Z-type polycarbonate resin) 105 parts THF (tetrahydrofuran) 1000 parts

Comparative Example 3 A photoconductor was prepared in the same manner as in Example 1, except that the composition of the photosensitive layer in Example 1 was changed as follows. Charge generating substance: X-type metal-free phthalocyanine 2 parts Hole transporting substance: 65 parts of hole transporting substance (HTM-1) Electron transporting substance: 28 parts of electron transporting substance (ETM-3 below) 28 parts Titanium oxide: P-25 ( Nippon Aerosil) (Average primary particle size: 21 nm) 20 parts Silicone oil: KF-54 (Shin-Etsu Chemical Co., Ltd.) 0.1 parts Binder resin: Panlite TS2020: (Teijin Chemical) (Bisphenol Z-type polycarbonate resin) 73 parts THF (Tetrahydrofuran) 1000 parts

[0067]

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Comparative Example 4 A photoconductor was prepared in the same manner as in Example 1, except that the composition of the photosensitive layer in Example 1 was changed as follows. Charge generating substance: X-type metal-free phthalocyanine 2 parts Hole transporting substance: 65 parts of hole transporting substance (HTM-1) Electron transporting substance: 28 parts of electron transporting substance (ETM-3) 28 parts Silicone oil: KF-54 ( Shin-Etsu Chemical Co., Ltd. 0.1 part Binder resin: Panlite TS2020: (Teijin Chemical) (bisphenol Z-type polycarbonate resin) 105 parts THF (tetrahydrofuran) 1000 parts

Comparative Example 5 A photoconductor was prepared in the same manner as in Example 1, except that the composition of the photosensitive layer in Example 1 was changed as follows. Charge generating substance: X-type metal-free phthalocyanine 2 parts Hole transporting substance: 65 parts of hole transporting substance (the above HTM-1) Electron transporting substance: 28 parts of electron transporting substance (the above ET1-3) Titanium oxide: TA300 (Fuji Titanium) ) (Average particle diameter 300 nm) 20 parts Silicone oil: KF-54 (Shin-Etsu Chemical Co., Ltd.) 0.1 part Binder resin: Panlite TS2020: (Teijin Kasei) (the bisphenol Z-type polycarbonate resin) 85 parts THF (tetrahydrofuran) 1000 copies

(Evaluation Method) (Sensitivity Characteristics) After charging the sample to 600 V by corona discharge, sensitivity was measured by continuously irradiating light having a wavelength of 780 nm and 1 μW / cm ² to attenuate the light. As a sensitivity value, a light amount (μJ / cm ² ) required for the surface potential to attenuate from 600 V to 300 V was measured.

(Repeating Characteristics and Image Evaluation) Using a laser printer HL-1060 (manufactured by Brother Industries, Ltd.),
In an environment of a temperature of 48 ° C. and a humidity of 48%, 10,000 images with a printing rate of about 5% were continuously printed, and the change in film thickness and the image evaluation were performed.

(Lifetime of Coating Solution) The coating solution prepared by the method shown in the example was placed in a sealed glass container, left at room temperature for one month in the dark, and then visually checked for sedimentation. The sedimentation state was determined by the presence or absence of a supernatant portion above the liquid. Table 1 also shows these evaluation results.

(Evaluation results)

[Table 1]

From the above results, in Comparative Example 5 in which the primary particle diameter of the titanium oxide fine particles was beyond the range of the present invention, sedimentation of the titanium oxide particles was observed in the coating solution. ) Was applied to the photosensitive layer. Using the photoreceptor manufactured by this process, continuous printing of 10,000 sheets was performed under the above-described conditions, and the image was evaluated thereafter. As a result, streak-like defects appeared on the image. Also, streak-like scratches were observed on the corresponding photoconductor surface. Upon examination, it was found that the large-diameter aggregated particles contained in the supernatant liquid entered the photosensitive layer once, and then the aggregated particles separated from the photosensitive layer came into contact with the rotating photoreceptor and caused a streak-like scratch. Turned out to be.

Regarding the change in the thickness of the photosensitive layer after continuous printing of 10,000 sheets, in Example 1 in which the titanium oxide fine particles were added, the decrease in the film thickness was 3.0 μm, whereas in Comparative Example which did not include titanium oxide. 5.5 μm and 5.6 for 1, 4 respectively
It can be seen that it is as large as μm. From Examples 1 to 7, the addition of metal oxide fine particles such as titanium oxide reduced the amount of film reduction to about half or less, and from the comparison with Comparative Example 1, a slight improvement in sensitivity was observed. However, Comparative Example 2
It is shown that the sensitivity is remarkably reduced when the electron transporting material according to the present invention is not used as shown in FIGS.

[0076]

As described above, according to the present invention,
In a positively charged organic photoreceptor provided with a single-layer type photosensitive layer containing metal oxide fine particles containing titanium oxide or tin oxide as a main component, the photosensitive layer has an average primary particle diameter of 50 nm or less. And a positively charged monolayer type organic photoreceptor containing an electron transporting substance represented by the chemical structural formula (1) or (2), so that a positively charged monolayer having a long life, high sensitivity and few image defects. Type organic photoreceptor can be provided.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of a positively charged single-layer type organic photoreceptor according to one embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Conductive support 2 Intermediate layer 3 Photosensitive layer 4 Protective layer

Claims (4)

[Claims] 1. In a positively charged organic photoreceptor having a single-layer type photosensitive layer containing metal oxide fine particles containing titanium oxide or tin oxide as a main component, the photosensitive layer has an average primary particle size of 50 nm or less. A positively-charged single-layer type organic photoreceptor comprising the metal oxide fine particles and an electron transporting substance represented by the following chemical structural formula (1) or (2).
(A and B are each an atomic group that satisfies the valency shown in the following chemical structural formula, and formula (2) includes the case without B. R ¹ to R ⁶ are each an H atom or C (carbon).
The alkyl group of 1 to 4 and X ¹ to X ³ each represent an H atom or a halogen atom, respectively. ) Embedded image 2. The positively charged single-layer type organic photoconductor according to claim 1, wherein the metal oxide fine particles are titanium oxide. 3. The positively charged single-layer organic photoconductor according to claim 1, wherein the metal oxide fine particles are indium tin oxide (ITO). 4. The positively charged single-layer organic photoconductor according to claim 1, wherein the metal oxide fine particles are antimony tin oxide (ATO).