JP2000147806A - Electrophotographic photoreceptor and electrophotographic apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a positively chargeable electrophotographic photoreceptor enhanced in sensitivity without causing a problem on stability and safety in repeated uses by using a specified compound for an electron transfer material and a specified compound for a hole transfer material. SOLUTION: The electron transfer material is a compound represented by formula I and the hole transfer material is represented by formula II and in formulae I and II, each of R1-R9 is an H or halogen atom or a 1-8C alkyl or alkoxy group or the like; A1 is an O atom or a CR10R11 group; each of R10 and R11 is a cyano or alkoxycarbonyl group; each of R30-R44 is, independently, an H atom or a 1-8C alkyl or alkoxy group; Ar is an aromatic hydrocarbon ring or hetero ring; (n) is 2, 3, or 4; (m) is an integer of 0-6; and (k) is 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 photoreceptor (hereinafter, also simply referred to as "photoreceptor") and an electrophotographic apparatus provided with the electrophotographic photoreceptor. The present invention relates to a suitable electrophotographic photoconductor and an electrophotographic apparatus provided with the electrophotographic photoconductor.

[0002]

2. Description of the Related Art Conventionally, an inorganic photoconductive material such as selenium or a selenium alloy has been used as a photosensitive layer of an electrophotographic photosensitive member.
A material in which an inorganic photoconductive substance such as zinc oxide or cadmium sulfide is dispersed in a resin binder (resin binder) has been used. In recent years, research on electrophotographic photoreceptors using an organic photoconductive substance has been advanced, and the photoreceptor has been put to practical use with improved sensitivity and durability.

A photoreceptor is required to have a function of retaining a surface charge in a dark place, a function of receiving light to generate a charge, and a function of receiving light and transporting a charge. A so-called single-layer type photoreceptor that combines these functions in layers, and a layer that separates functions into a layer that mainly contributes to charge generation and a layer that contributes to charge retention and surface charge retention in dark places and charge transport during photoreception. There is a so-called laminated type photoreceptor in which are laminated. For image formation by electrophotography using these photoconductors,
For example, the Carlson method is applied. Image formation in this method involves charging a photoreceptor by corona discharge in a dark place, forming an electrostatic latent image such as a character or picture of a document on the charged photoreceptor surface, and forming the formed electrostatic latent image. The image is developed with toner, and the developed toner image is fixed on a support such as paper.After transfer of the toner image, the photoreceptor is subjected to charge removal, removal of residual toner, light charge removal, etc. Provided.

[0004] Practically used organic photoreceptors have advantages such as flexibility, film forming property, low cost and safety as compared with inorganic photoreceptors. Improvements are underway. Most organic photoreceptors
This is a stacked type photoconductor in which functions are separated into a charge generation layer and a charge transport layer. In general, a laminated organic photoreceptor is obtained by sequentially forming a charge generation layer composed of a charge generation substance such as a pigment and a dye, and a charge transport layer composed of a charge transport substance such as hydrazone and triphenylamine on a conductive support. Due to the nature of the electron-transporting charge transporting substance, it becomes a hole-transfer type and has sensitivity when the surface of the photoreceptor is negatively charged. However, in the case of negative charging, corona discharge used during charging is more unstable than in the case of positive charging, and ozone and nitrogen oxides are generated and are likely to be physically and chemically deteriorated by being adsorbed on the surface of the photoreceptor. Is worse. From such a point, as the photosensitive member, a positive charging type photosensitive member having a greater degree of freedom of use conditions than the negative charging type photosensitive member has a wider application range and is advantageous.

Therefore, various photoconductors for use in positive charging have been proposed. For example, a method in which a charge generating substance and a charge transporting substance are simultaneously dispersed in a resin binder and used as a single photosensitive layer has been proposed and partially put to practical use. However, the sensitivity is not sufficient for application to a high-speed machine, and further improvement is required in terms of repetition characteristics and the like. Further, a method of forming a photoreceptor by stacking a charge generation layer on a charge transport layer to form a photoreceptor, and using it with positive charge may be considered for the purpose of increasing sensitivity. However, in this method, since a thin charge generation layer having a thickness of 1 μm or less is usually formed on the surface, there is a problem in stability during repeated use due to corona discharge, light irradiation, mechanical abrasion, and the like. In this case, it has been proposed to further provide a protective layer on the charge generation layer. However, although mechanical wear is improved, there is a problem that electrical characteristics such as sensitivity are lowered.

Further, there has been proposed a method of forming a photoreceptor by laminating a charge transporting layer having an electron transporting property on a charge generating layer. As an electron transporting material, 2,4,7-trinitro-
Although 9-fluorenone and the like are known, this substance is carcinogenic and has a safety problem. In addition, cyano compounds, quinone compounds and the like are disclosed in JP-A-50-131941.
JP-A-6-59483, JP-A-6-1223986
And JP-A No. 9-190003, but it is a fact that a compound having an electron transporting ability sufficient for practical use has not been obtained.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and has high sensitivity without causing any problem in stability and safety during repeated use. It is an object of the present invention to provide a positively chargeable electrophotographic photoconductor for machines and printers, and an electrophotographic apparatus using the electrophotographic photoconductor.

[0008]

In order to solve the above-mentioned problems, the present inventor has conducted intensive studies on various kinds of organic materials. Among them, it is possible to use a compound having a specific skeleton represented by the following general formula (I) or (II) in combination with a compound having a specific skeleton represented by the following general formula (III). The present inventors have found that a highly sensitive photoreceptor which can be used with positive charge and which can be used without causing the above-mentioned problems can be obtained, and the present invention has been completed.

That is, the electrophotographic photoreceptor of the present invention is an electrophotographic photoreceptor having a photosensitive layer containing a charge generating substance, a hole transporting substance, and an electron transporting substance on a conductive supporting substrate. At least one of the transport substances has the following general formula (I): (Wherein, R ^{1 to} R ⁹ are each a hydrogen atom, a halogen atom, an alkyl group having 1 to 8 carbon atoms, an alkoxy group, a halogenated alkyl group, a halogenated alkoxy group, or an aryl group which may have a substituent. And may be the same or different from each other, or two or more groups out of R ^{1 to} R ⁹ may combine to form a ring, and A ¹ is an oxygen atom or CR ¹⁰
R ¹¹ (R ¹⁰ and R ¹¹ each represent a cyano group or an alkoxycarbonyl group), wherein at least one of the hole transporting substances is represented by the following general formula (III): (Wherein, R ^{30 to} R ⁴⁴ each represent a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, or an alkoxy group, which may be the same or different, and Ar is an aromatic hydrocarbon or an aromatic heterocyclic ring, n is an integer of 2 to 4, m is an integer of 0 to 6, and k represents 1 or 2).

Another electrophotographic photoreceptor of the present invention is an electrophotographic photoreceptor having a photosensitive layer containing a charge generating substance, a hole transporting substance, and an electron transporting substance on a conductive support substrate. At least one of the transport substances has the following general formula (II): (Wherein, R ^{12 to} R ²⁹ each represent a hydrogen atom, a halogen atom, an alkyl group having 1 to 8 carbon atoms, an alkoxy group, a halogenated alkyl group, a halogenated alkoxy group, or an aryl group which may have a substituent. And may be the same or different from each other, or 2 of R ^{12 to} R ²⁹
One or more groups are joined to form a ring, and B ¹ and B ² are each an oxygen atom or CR ¹⁰ R ¹¹ (R ¹⁰ and R ¹¹
Represents a cyano group or an alkoxycarbonyl group, respectively), wherein at least one of the hole transporting substances is represented by the following general formula (III): (Wherein, R ^{30 to} R ⁴⁴ each represent a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, or an alkoxy group, which may be the same or different, Ar is an aromatic hydrocarbon or an aromatic heterocyclic ring, n is an integer of 2 to 4, m is an integer of 0 to 6, and k represents 1 or 2).

The electrophotographic photoreceptor of the present invention preferably has a single-layer type photosensitive layer.

Further, an electrophotographic apparatus according to the present invention is provided with the electrophotographic photosensitive member.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Specific examples of the compounds represented by formulas (I), (II) and (III) are shown below, but the present invention is not limited thereto.

[0014]

[0015]

[0016]

[0017]

[0018]

[0019]

[0020]

The compounds of the general formulas (I) and (II) used in the present invention can be synthesized by a usual method. For example, the compounds represented by the formulas (I-1) and (II-2) can be obtained by converting the compounds represented by the following structural formulas (1) and (2) to a suitable oxidizing agent, for example, potassium permanganate. For example, the compound can be easily synthesized by oxidation in an organic solvent such as chloroform.

[0022]

FIGS. 1 to 3 are schematic sectional views showing a single-layer type photosensitive member according to an embodiment of the present invention. In the figure, 1 is a conductive support substrate, 2 is an undercoat layer (intermediate layer), 3
Denotes a photosensitive layer, and 4 denotes a surface protective layer (coating layer).

The photoreceptor shown in FIG. 1 is provided with a photosensitive layer 3 formed by dispersing a charge generating substance and a charge transporting substance in a resin binder (binder) on a conductive support substrate 1. This is a configuration generally referred to as a single-layer type photoreceptor.
The photoreceptor shown in FIG. 2 has a similar photosensitive layer 3 provided on a conductive support base 1 via an undercoat layer 2. The photoreceptor shown in FIG. 3 is obtained by further providing a surface protective layer 4 on the photoreceptor shown in FIG. In addition, the undercoat layer 2 and the surface protection layer 4 are provided as needed.

In the photoreceptor shown in FIGS. 1 to 3, a charge generating substance is dispersed in a solution in which a charge transporting substance and a resin binder are dissolved, and this dispersion is placed on the conductive support base 1 or the conductive support. It can be produced by applying the undercoat layer 2 on the base 1 and applying the same. If necessary, a surface protective layer 4 is formed by coating.

The conductive support substrate 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. Metals such as steel, nickel, or the like, or those obtained by performing a conductive treatment on glass, resin, or the like can be used.

The undercoat layer 2 can be provided as needed, and is made of a layer mainly composed of a resin, an oxide film such as alumite, or the like, and transfers an unnecessary charge from the conductive support base 1 to the photosensitive layer 3. It is provided as necessary for the purpose of preventing injection, covering defects on the surface of the supporting substrate, improving the adhesiveness to the photosensitive layer 3, and the like. As the resin binder, polycarbonate resin,
Polyester resin, polyvinyl acetal resin, polyvinyl butyral 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, poly An arylate resin, a polysulfone resin, a polymer of methacrylic acid ester, a copolymer thereof, or the like can be used in an appropriate combination. In the resin binder, metal oxides such as silicon oxide (silica), titanium oxide, zinc oxide, calcium oxide, aluminum oxide (alumina), and zirconium oxide; metal sulfides such as barium sulfide and calcium sulfide; silicon nitride And fine particles of metal nitrides such as aluminum nitride and metal oxides.

In the case of the undercoat layer containing a resin as a main component, an electron transport material such as a quinone compound can be contained for the purpose of imparting electron transport properties and reducing charge traps.

The thickness of the undercoat layer 2 depends on the composition of the undercoat layer, but can be arbitrarily set within a range that does not cause adverse effects such as an increase in residual potential when used repeatedly and continuously.

The photosensitive layer 3 is mainly composed of a charge generating substance, an electron transporting substance, a hole transporting substance, and a resin binder, and an additive may be added as needed.

As the charge generating substance, phthalocyanine pigments, azo pigments, anthantrone pigments, perylene pigments, perinone pigments, squarylium pigments, thiapyrylium pigments, quinacridone pigments and the like can be used, and these pigments can be used in combination. Is also good. In particular, azo pigments include disazo pigments, trisazo pigments, and perylene pigments include N, N'-bis (3,5-dimethylphenyl) -3,4: 9,10-perylenebis (carboxyimide) and phthalocyanine pigments. Are preferably metal-free phthalocyanine, copper phthalocyanine, and titanyl phthalocyanine, and more preferably 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, CuKα described in Japanese Patent Application Laid-Open No. Hei 8-209023: Bragg angle 2θ in X-ray diffraction spectrum
Is preferably titanyl phthalocyanine having a maximum peak at 9.6 °.

As the electron transporting material, the above-mentioned general formula (I)
Or a compound represented by (II), but other than this, succinic anhydride, maleic anhydride, dibromosuccinic anhydride, phthalic anhydride, 3-nitrophthalic anhydride, 4-nitrophthalic anhydride, pyromellitic anhydride Acid, pyromellitic acid, trimellitic acid, trimellitic anhydride, phthalimide, 4-nitrophthalimide, tetracyanoethylene,
Tetracyanoquinodimethane, chloranil, bromanil,
o-nitrobenzoic acid, trinitrofluorenone, quinone, diphenoquinone, naphthoquinone, anthraquinone,
Electron-transporting substances such as benzoquinone, stilbenequinone and derivatives thereof can also be used in combination.

As the hole transport material, the above-mentioned general formula (II)
The triphenylamine compound represented by I) is used, but other hydrazone compounds, pyrazoline compounds,
A hole transport substance such as a pyrazolone compound, an oxadiazole compound, an oxazole compound, an arylamine compound, a benzidine compound, a stilbene compound, a styryl compound, polyvinyl carbazole, or polysilane may be used in combination. Examples of the electron transporting substance and the hole transporting substance which may be used in combination are shown below, but are not limited thereto.

[0034]

[0035]

[0036]

[0037]

[0038]

[0039]

[0040]

[0041]

[0042]

As the resin binder, polycarbonate resin, polyester resin, polyvinyl acetal resin, polyvinyl butyral resin, vinyl chloride resin, vinyl acetate resin, polyethylene, polypropylene, polystyrene, acrylic resin, polyurethane resin, epoxy resin, melamine resin, silicone resin , Polyamide resin,
A polystyrene resin, a polyacetal resin, a polyarylate resin, a polysulfone resin, a polymer of methacrylic acid ester, a copolymer thereof, and the like can be appropriately used in combination. Particularly, a polycarbonate resin or a polyester resin having one or more structural units (V-1) to (V-7) shown below is suitable, and a mixture of two or more of these resins is used. You may.

[0044]

The thickness of the photosensitive layer 3 is preferably in the range of 3 to 50 μm, more preferably 10 to 40 μm, in order to maintain a practically effective surface potential.

The photosensitive layer 3 may contain a deterioration inhibitor such as an antioxidant or a light stabilizer for the purpose of improving environmental resistance and stability against harmful light. Compounds used for such purposes include chromanol derivatives such as tocopherol, esterified compounds, polyarylalkane compounds, hydroquinone derivatives, etherified compounds, dietherified compounds, benzophenone derivatives,
Examples include benzotriazole derivatives, thioether compounds, phenylenediamine derivatives, phosphonic acid esters, phosphite esters, phenol compounds, hindered phenol compounds, linear amine compounds, cyclic amine compounds, hindered amine compounds, and the like.

Further, the photosensitive layer 3 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.

The protective layer 4 can be provided as needed for the purpose of improving printing durability and the like, and is made of a layer mainly composed of a resin binder or an inorganic thin film such as amorphous carbon. Also, in the resin binder, silicon oxide (silica), titanium oxide, zinc oxide, calcium oxide, aluminum oxide (alumina), oxide Metal oxides such as zirconium, metal sulfides such as barium sulfate and calcium sulfate, metal nitrides such as silicon nitride and aluminum nitride, fine particles of metal oxides, fluorine-based resins such as ethylene tetrafluoride resin, and fluorine-based resin Particles such as a type graft polymerization resin may be contained.

For the purpose of imparting charge transport properties to the protective layer 4, the charge transporting substance and electron accepting substance used in the above-described photosensitive layer and the compound according to the present invention are contained, and the leveling property of the formed film is determined. For the purpose of improving the lubrication and imparting lubricity, a leveling agent such as silicone oil or fluorine-based oil may be contained.

The film thickness of the protective layer 4 itself depends on the composition of the protective layer, but can be arbitrarily set within a range that does not cause adverse effects such as an increase in residual potential when used repeatedly and continuously.

[0051]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to embodiments. Example 1 Dip coating was performed on a 30 mmφ aluminum base tube using a coating solution prepared by dissolving 3 parts by weight of soluble nylon (Amilan CM8000: manufactured by Toray Industries, Inc.) in a mixed solution of 50 parts by weight of methanol and 50 parts by weight of methylene chloride. And then 10
After drying at 0 ° C. for 60 minutes, an undercoat layer of about 0.3 μm was formed.

Next, an X-type metal-free phthalocyanine (H ₂
0.3 parts by weight of Pc) and the above-mentioned formula (I)
-3), 2 parts by weight of the compound represented by the above formula (III-2) as a hole transport material, and a bisphenol Z-type polycarbonate resin (Panlite T
S2050: Teijin Chemicals Ltd. (10 parts by weight) and methylene chloride (100 parts by weight) were kneaded with a mixer for 3 hours to prepare a coating solution, and dip-coated on the undercoating layer.
Dried at 60 ° C. for 60 minutes to form a photosensitive layer of about 25 μm,
A single-layer photoreceptor was prepared.

Example 2 The compound (I-3) used in Example 1 was replaced with the compound (II-
A photoconductor was prepared in the same manner as in Example 1, except that 2) was used instead.

Example 3 The compound (III-2) used in Example 1 was replaced with the compound (III-
A photoconductor was prepared by the same way as that of Example 1 except for changing to 4).

Example 4 The compound (I-3) used in Example 1 was replaced with the compound (II-
A photoconductor was prepared by the same way as that of Example 1 except that compound (III-2) was changed to compound (III-4) in 2).

Comparative Example 1 The compound (I-3) used in Example 1 was replaced with the compound (IV-5)
A photoconductor was prepared by the same way as that of Example 1 except that 6) was used instead.

Comparative Example 2 The compound (III-2) used in Example 1 was replaced with the compound (IV-
A photoconductor was prepared by the same way as that of Example 1 except for changing to 14).

Comparative Example 3 The compound (I-3) used in Example 1 was replaced with the compound (IV-5)
A photoconductor was prepared by the same way as that of Example 1 except that compound (III-2) was replaced by compound (IV-14) in 6).

In Examples 1-4 and Comparative Examples 1-3, in an environment at a temperature of 23 ° C. and a humidity of 50%, the surface potential was charged to about +600 V in a dark place, and then 5 seconds until exposure. Of the surface potential was determined by the following equation. Retention Vk5 (%) = V5 / V0 × 100 V0: Surface potential immediately after charging V5: Surface potential after 5 seconds (at the start of exposure)

Next, monochromatic light of 1.0 μW / cm ² , which is obtained by dividing the light of a halogen lamp with a filter to 780 nm, is exposed for 5 seconds, and the exposure amount required to reduce the surface potential to half (+300 V) is determined by the sensitivity E. calculated as _{1/2 (μJ} / cm ^2), it was determined and the surface potential of 5 seconds after exposure as residual potential Vr (V). The results obtained are shown in Table 1 below.

[0061]

[Table 1]

[0062]

As described above, according to the present invention, a combination of an electron transporting substance having a specific skeleton and a hole transporting substance having a specific skeleton is contained in a photosensitive layer of an electrophotographic photosensitive member. As a result, an electrophotographic photosensitive member having excellent electrical characteristics, particularly excellent sensitivity and residual potential, can be obtained, and is particularly useful for a printer, a copying machine, a facsimile, etc. using a positive charging type electrophotographic method.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view of a single-layer type electrophotographic photoconductor according to the present invention.

FIG. 2 is a schematic sectional view of another single-layer type electrophotographic photoconductor according to the present invention.

FIG. 3 is a schematic sectional view of still another single-layer type electrophotographic photoreceptor according to the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 conductive substrate 2 undercoat layer 3 photosensitive layer 4 protective layer

Claims (4)

[Claims] 1. An electrophotographic photoreceptor having a photosensitive layer containing a charge generating substance, a hole transporting substance and an electron transporting substance on a conductive support substrate, wherein at least one of the electron transporting substances has the following general formula: (I), (Wherein, R ^{1 to} R ⁹ are each a hydrogen atom, a halogen atom, an alkyl group having 1 to 8 carbon atoms, an alkoxy group, a halogenated alkyl group, a halogenated alkoxy group, or an aryl group which may have a substituent. And may be the same or different from each other, or two or more groups out of R ^{1 to} R ⁹ may combine to form a ring, and A ¹ is an oxygen atom or CR ¹⁰
R ¹¹ (R ¹⁰ and R ¹¹ each represent a cyano group or an alkoxycarbonyl group), wherein at least one of the hole transporting substances is represented by the following general formula (III): (Wherein, R ^{30 to} R ⁴⁴ each represent a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, or an alkoxy group, which may be the same or different, and Ar is an aromatic hydrocarbon or an aromatic heterocyclic ring, n is an integer of 2 to 4, m is an integer of 0 to 6, and k represents 1 or 2.) 2. An electrophotographic photoreceptor having a photosensitive layer containing a charge generating substance, a hole transporting substance and an electron transporting substance on a conductive support substrate, wherein at least one of the electron transporting substances has the following general formula: (I
I), (Wherein, R ^{12 to} R ²⁹ each represent a hydrogen atom, a halogen atom, an alkyl group having 1 to 8 carbon atoms, an alkoxy group, a halogenated alkyl group, a halogenated alkoxy group, or an aryl group which may have a substituent. And may be the same or different from each other, or 2 of R ^{12 to} R ²⁹
One or more groups are joined to form a ring, and B ¹ and B ² are each an oxygen atom or CR ¹⁰ R ¹¹ (R ¹⁰ and R ¹¹
Represents a cyano group or an alkoxycarbonyl group, respectively), wherein at least one of the hole transporting substances is represented by the following general formula (III): (Wherein, R ^{30 to} R ⁴⁴ each represent a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, or an alkoxy group, which may be the same or different, and Ar is an aromatic hydrocarbon or an aromatic heterocyclic ring, n is an integer of 2 to 4, m is an integer of 0 to 6, and k represents 1 or 2.) 3. An electrophotographic photoconductor according to claim 1, wherein said photosensitive layer is a single-layer type photosensitive layer. 4. An electrophotographic apparatus comprising the electrophotographic photoreceptor according to claim 1.