JP5540956B2 - Electrophotographic photosensitive member and electrophotographic apparatus - Google Patents

Description

  The present invention relates to an electrophotographic photoreceptor containing a specific disazo pigment as a charge generating agent and a specific indoline compound as a charge transporting agent, as well as an electrophotographic apparatus, an electrophotographic method and an electron using the electrophotographic photoreceptor. The present invention relates to a process cartridge for a photographic apparatus.

  In recent years, long-wavelength light sources such as semiconductor lasers and LEDs have been mainly used as exposure light sources for non-impact printers that employ electrophotography. Furthermore, with the miniaturization and speeding up of copiers and printers, processes for reducing the diameter of electrophotographic photosensitive members and increasing the peripheral speed have been adopted. Therefore, the electrophotographic photosensitive member generally uses a charge generating agent having sensitivity in a long wavelength region. Conventionally, phthalocyanine pigments are often used as such materials. It is well known that the sensitivity of this phthalocyanine pigment varies depending on its crystal form. Further, with the recent power saving, there is an increasing demand for high sensitivity in the electrophotographic photosensitive member in order to suppress the output of the exposure light source of the electrophotographic apparatus such as a printer.

  Among the phthalocyanine pigments, oxytitanium phthalocyanine is mentioned as one having high sensitivity in a long wavelength region near 780 nm. Among them, the one showing the maximum diffraction peak at 27.2 ° is considered to have high sensitivity. However, when used in a high-speed process, the potential characteristics of the electrophotographic photosensitive member after repeated use deteriorate, and fog, black streaks, density unevenness and the like occur in the obtained image. In addition, due to the high sensitivity characteristics of oxytitanium phthalocyanine, the amount of generated charges is relatively large, so it usually has advantages such as high response, but when used in high-speed processes, charges remain in the photosensitive layer. It is considered that the memory remains on the electrophotographic photosensitive member and appears in the image as a memory phenomenon in the next electrophotographic process. Further, it has a negative factor that the charge in the photosensitive layer remains with respect to environmental conditions from low temperature and low humidity to high temperature and high humidity. Recently, attention has been focused on azo pigments having sensitivity in the vicinity of a wavelength of 650 nm. (For example, refer to Patent Documents 1 and 2.) However, the molecular skeleton of the azo pigment affects the charge generation efficiency, and the charge generation efficiency also changes in combination with the charge transport agent. There is also a relationship with the transport capability, and the combination of both is important as an electrophotographic photoreceptor.

  Therefore, an electrophotographic photosensitive member having high sensitivity and high photoresponsiveness in a long wavelength region and having stable reproducibility of electrophotographic characteristics, particularly initial potential and potential after repeated use, even when used repeatedly at high speed is desired. It has been. Even if a charge generating agent having a high charge generating efficiency is used, not only a sufficient sensitivity cannot be obtained if the charge transporting agent has a low transporting ability or is incompatible with the charge transporting agent, but also high temperature and high humidity. High-quality images cannot be obtained even in various usage environments from low temperature to low humidity. The compatibility between the charge generating agent and the charge transporting agent has been studied from various viewpoints, but it has not been clearly found at present.

  For example, in Patent Document 3 (Japanese Patent Application Laid-Open No. 3-75660), an electrophotographic photosensitive material using an indoline-based charge transporting substance having a specific structure (different from the indoline-based charge transporting agent in the present invention) for the charge transporting layer. The body is disclosed. Similarly, Patent Document 4 (Japanese Patent Laid-Open No. 5-6011) and Patent Document 5 (Japanese Patent Laid-Open No. 11-149170) disclose different charge transport agents that are close to the structure of the charge transport agent in the present invention. . However, the charge transfer agents disclosed in Patent Documents 3 to 5 cannot sufficiently satisfy various characteristics required for the above-described electrophotographic photosensitive member.

The present invention aims to solve the above-mentioned problems of the prior art, and is compatible with the process of reducing the diameter of the electrophotographic photosensitive member and increasing the peripheral speed as the electrophotographic apparatus such as a copying machine and a printer becomes smaller and faster. The present invention provides an electrophotographic photosensitive member that can be electrophotographic photosensitive member, has high sensitivity and high photoresponsiveness in a long wavelength region, has no deterioration in electrical characteristics even after repeated use, and has high stability. Objective.
Another object of the present invention is to provide an electrophotographic apparatus, an electrophotographic method, and a process cartridge for an electrophotographic apparatus using the electrophotographic photosensitive member.

As a result of intensive studies to solve the above problems, the present inventors have used an electrophotographic photoreceptor using a specific asymmetric disazo pigment as a charge generator and a specific indoline compound as a charge transport agent. Has been found to solve the problem, and the present invention has been completed.
That is, the said subject is solved by the following this invention.

(1): An electrophotographic photosensitive member having a conductive support and a photosensitive layer provided on the conductive support, wherein the photosensitive layer includes a binder resin, a charge generating agent, a charge The charge generating agent contains an asymmetric disazo pigment represented by the following general formula (I), and the charge transporting agent contains an indoline compound represented by the following general formula (II) An electrophotographic photosensitive member characterized in that:

(In the general formula (I), R ₁ and R ₂ each independently represents a substituted or unsubstituted alkyl group, alkoxy group, aryl group, or heterocyclic group, provided that R ₁ and R ₂ are the same as each other. Excluding those that are.)

(In the general formula (II), R _{3 to} R ₆ each independently represents a hydrogen atom, a halogen atom, an alkyl group having 1 to 6 carbon atoms which may have a substituent, or an alkoxy having 1 to 6 carbon atoms. Represents a group.)

(2) The electrophotographic photosensitive member according to the above (1), wherein the charge transfer agent contains an indoline compound represented by the following chemical formula (IIa).

(3) The electrophotographic photosensitive member according to (1), wherein the charge transfer agent contains an indoline compound represented by the following chemical formula (IIb).

(4) The electrophotographic photosensitive member according to (1) above, wherein the charge transport agent contains an indoline compound represented by the following chemical formula (IIc).

(5) The electrophotographic photosensitive member according to the above (1), wherein the charge transfer agent contains an indoline compound represented by the following chemical formula (IId).

(6) The electrophotographic photosensitive member according to (1) above, wherein the charge transport agent contains an indoline compound represented by the following chemical formula (IIe).

(7): The photosensitive layer according to (1), wherein the photosensitive layer includes a charge generation layer containing the charge generation agent and a charge transport layer containing the charge transfer agent. Is the body.

(8) The electrophotographic photosensitive member according to (7), wherein the charge transport layer contains a phenol-based antioxidant.

(9) The electrophotographic photosensitive member according to (7), wherein the charge transport layer contains an amine-based antioxidant.

(10) The electrophotographic photosensitive member according to (7), wherein the charge transport layer contains a sulfur-based antioxidant.

(11) The electrophotographic photosensitive member according to (7), wherein the charge transport layer contains a benzotriazole ultraviolet absorber.

(12): The electrophotographic photosensitive member according to any one of the above (1) to (11), charging means for charging the surface of the electrophotographic photosensitive member, and electrostatic charge on the surface of the charged electrophotographic photosensitive member. An electrophotographic process comprising: an exposure unit that forms a latent image; a developing unit that visualizes the electrostatic latent image with toner to form a toner image; and a transfer unit that transfers the toner image onto a recording medium. An electrophotographic apparatus is characterized in that it does not have a neutralizing means for neutralizing a photoreceptor.

(13) The electrophotographic apparatus according to (12), wherein the electrophotographic photosensitive member is a tandem type including a plurality of the electrophotographic photosensitive member, the charging unit, the developing unit, and the transfer unit.

(14): The developing unit forms one or more toner images, and the transfer unit includes a primary transfer unit, an intermediate transfer member, and a secondary transfer unit, and the primary transfer unit includes: The toner image on the electrophotographic photosensitive member is primarily transferred onto the intermediate transfer member, the secondary transfer unit secondarily transfers the toner image on the intermediate transfer member onto a recording medium, and the developing unit includes: When forming two or more toner images, the primary transfer unit performs primary transfer so that the two or more toner images are stacked on the intermediate transfer member, and the secondary transfer unit includes the secondary transfer unit on the recording medium. The electrophotographic apparatus according to (12) or (13), wherein two or more toner images stacked on the intermediate transfer member are secondarily transferred collectively.

(15): A charging step for charging the electrophotographic photosensitive member, an exposure step for forming an electrostatic latent image on the charged surface of the electrophotographic photosensitive member, and forming the toner image by visualizing the electrostatic latent image with toner. An electrophotographic method comprising: a developing step for transferring; and a transferring step for transferring the toner image onto a recording medium, wherein the electrophotographic photosensitive member is any one of (1) to (11) above. The electrophotographic method is characterized in that the time required from the exposure step to the development step is 100 milliseconds or less.

(16): One or more means selected from charging means, exposure means, developing means, cleaning means, and transfer means, and the electrophotographic photosensitive member according to any one of (1) to (11) above And a process cartridge for an electrophotographic apparatus.

  According to the present invention, the electrophotographic photosensitive member can be reduced in size and increased in speed with the reduction in diameter of the electrophotographic apparatus, and can be used in a process with a high peripheral speed, and has high sensitivity and high photoresponsiveness in a long wavelength range. An electrophotographic photosensitive member that does not deteriorate in electrical characteristics even after repeated use and has high stability, and an electrophotographic apparatus, an electrophotographic method, and a process cartridge for an electrophotographic apparatus using the electrophotographic photosensitive member are obtained.

1 is a cross-sectional view showing a configuration in an embodiment of an electrophotographic photosensitive member according to the present invention. 1 is a schematic configuration diagram showing a configuration in an embodiment of an electrophotographic apparatus according to the present invention.

  The electrophotographic photoreceptor according to the present invention is an electrophotographic photoreceptor having a conductive support and a photosensitive layer provided on the conductive support, and the photosensitive layer includes a binder resin, A charge generator, and a charge transport agent, the charge generator contains an asymmetric disazo pigment represented by the following general formula (I), and the charge transport agent is represented by the following general formula (II): It is characterized by containing an indoline compound.

(In the general formula (I), R ₁ and R ₂ each independently represents a substituted or unsubstituted alkyl group, alkoxy group, aryl group, or heterocyclic group, provided that R ₁ and R ₂ are the same as each other. Excluding those that are.)

(In the general formula (II), R _{3 to} R ₆ each independently represents a hydrogen atom, a halogen atom, an alkyl group having 1 to 6 carbon atoms which may have a substituent, or an alkoxy having 1 to 6 carbon atoms. Represents a group.)

  Next, a preferred embodiment of an electrophotographic photoreceptor according to the present invention (hereinafter sometimes simply referred to as a photoreceptor) will be described with reference to the drawings. Although the embodiments described below are preferred embodiments of the present invention, various technically preferable limitations are attached thereto, but the scope of the present invention is intended to limit the present invention in the following description. Unless otherwise described, the present invention is not limited to these embodiments.

  FIG. 1 is a cross-sectional view showing a structural example of the electrophotographic photosensitive member of the present invention. A function in which a charge generation layer (2) containing at least a charge generation agent is formed on a conductive support (1), and a charge transport layer (3) containing at least a charge transfer agent is formed thereon. A separation type electrophotographic photosensitive member is applied. In this case, the photosensitive layer (4) is formed by the charge generation layer (2) and the charge transport layer (3).

  Various methods can be used as a method for forming the charge generation layer (2). For example, an asymmetric disazo pigment represented by the general formula (I) is used as a charge generation agent and is appropriately used together with a binder resin. A coating solution dispersed or dissolved in a solvent can be formed on a conductive support (1) serving as a predetermined base and dried as necessary.

  The charge transport layer (3) has at least a charge transport agent which is an indoline compound represented by the general formula (II). The charge transport layer (3) can be formed, for example, by binding a charge transport agent on the charge generation layer (2) serving as the base using a binder resin.

  Various methods can be used as a method for forming the charge transport layer (3). In general, a coating liquid in which a charge transport agent is dispersed or dissolved in a suitable solvent together with a binder resin is used as a base. A method of coating on the charge generation layer (2) and drying can be used.

  The present invention is not limited to this, and can also be applied to an inversely laminated electrophotographic photosensitive member in which the charge generation layer (2) and the charge transport layer (3) are laminated upside down. Furthermore, the present invention can also be applied to a single layer type electrophotographic photosensitive member containing a charge generating agent and a charge transporting agent in the same layer (single layer photosensitive layer (4)). If necessary, an undercoat layer (intermediate layer) may be provided between the conductive support (1) and the charge generation layer (2), or a protective layer may be provided on the photosensitive layer (4). good.

  Examples of the conductive support (1) that can be used in the present invention include simple metals such as aluminum, brass, stainless steel, nickel, chromium, titanium, gold, silver, copper, tin, platinum, molybdenum, indium, and the like. An alloy processed body may be mentioned. The shape may be a flexible shape such as a sheet shape, a film shape, or a belt shape, or may be an inflexible shape such as a drum shape, and may be endless or endless. The diameter of the conductive support (1) is particularly effective when it is 60 mm or less, preferably 30 mm or less.

  Among these, aluminum alloys such as JIS 3000, JIS 5000, and JIS 6000 are used, and general methods such as an EI (Extension Ironing) method, an ED (Extension Drawing) method, a DI (Drawing Ironing) method, and an II (Impact Ironing) method are used. A conductive support formed by a simple method is preferable, and the surface of the conductive support is further subjected to surface treatment such as diamond cutting or polishing, surface treatment such as anodizing treatment, or these treatments and treatments. Anything such as a non-cutting tube which is not performed may be used.

  When using a resin as the conductive support (1), a conductive agent such as metal powder or conductive carbon may be contained in the resin, or a conductive resin may be used as the conductive support forming resin. it can.

  Furthermore, when glass is used for the conductive support (1), the surface thereof may be coated with tin oxide, indium oxide, or aluminum iodide to provide conductivity.

  Further, an undercoat layer may be formed on the conductive support (1). This undercoat layer has a function of improving adhesion, a barrier function for preventing an inflow current from the aluminum tube, a defect covering function for the surface of the aluminum tube, and the like. This undercoat layer is made of various resins such as polyethylene resin, acrylic resin, epoxy resin, polycarbonate resin, polyurethane resin, vinyl chloride resin, vinyl acetate resin, polyvinyl butyral resin, polyamide resin, nylon resin, alkyd resin, melamine resin, etc. The undercoat layer may be composed of a single resin selected from these, or may be composed of a mixture of two or more resins. Moreover, a metal compound, carbon, silica, resin powder, etc. can be dispersed in the undercoat layer. Further, various pigments, electron accepting substances, electron donating substances and the like can be contained in the undercoat layer for improving the characteristics.

  These undercoat layers can be formed by using an appropriate solvent, dispersion, and coating method in the same manner as the photosensitive layer (4). The film thickness of the undercoat layer is 0.1 μm to 50 μm, preferably 0.5 μm to 20 μm.

As the charge generating agent, an asymmetric disazo pigment represented by the general formula (I) is used. Specific examples of the asymmetric disazo pigment used are shown in Table 1 below. R ₁ and R ₂ are not the same at the same time.

  In the photosensitive layer (4), in addition to the asymmetric disazo pigment represented by the general formula (1), other azo pigments such as monoazo pigments, bisazotones are used in order to obtain an appropriate photosensitivity wavelength and sensitizing action. Pigments, trisazo pigments, polyazo pigments, indigo pigments, selenium pigments, toluidine pigments, pyrazoline pigments, perylene pigments, quinacridone pigments, pyrylium salts, and the like can be used. In addition, phthalocyanine pigments, perylene pigments, and the like can also be mixed. These are desirable in terms of good sensitivity compatibility.

  The binder resin for forming the photosensitive layer (4) includes polycarbonate resin, styrene resin, acrylic resin, styrene-acrylic resin, ethylene-vinyl acetate resin, polypropylene resin, vinyl chloride resin, chlorinated polyether, vinyl chloride. -Vinyl acetate resin, polyester resin, furan resin, nitrile resin, alkyd resin, polyacetal resin, polymethylpentene resin, polyamide resin, polyurethane resin, epoxy resin, polyarylate resin, diarylate resin, polysulfone resin, polyethersulfone resin, poly Allyl sulfone resin, silicone resin, ketone resin, polyvinyl butyral resin, polyether resin, phenol resin, EVA (ethylene / vinyl acetate) resin, ACS (acrylonitrile / chlorinated polyethylene / styrene) Resins, ABS (acrylonitrile butadiene styrene) include resins and epoxy polyarylate resin.

  They may be used alone or in combination of two or more. It is preferable to use a mixture of resins having different molecular weights because the hardness and wear resistance can be improved.

  In the case where the photosensitive layer (4) comprises the charge generation layer (2) and the charge transport layer (3), the resin can be applied to either layer.

  The amount of the binder resin is 10 to 500 parts by weight, preferably 25 to 300 parts by weight with respect to 100 parts by weight of the charge generating agent.

  The film thickness of the charge generation layer (2) is 0.01 to 5 μm, preferably 0.1 to 2 μm.

  As a coating method of the coating solution, methods such as dip coating, spray coating, ring coating, bar coating spinner coating and the like can be used. In addition, about the coating method of this coating liquid, the charge transport layer (3) mentioned later can use the same method.

  Solvents used in the coating solution include alcohols such as methanol, ethanol, n-propanol, i-propanol and butanol, saturated aliphatic hydrocarbons such as pentane, hexane, heptane, octane, cyclohexane and cycloheptane, toluene and xylene. Aromatic hydrocarbons such as dichloromethane, chlorinated hydrocarbons such as dichloromethane, dichloroethane, chloroform, chlorobenzene, ethers such as dimethyl ether, diethyl ether, tetrahydrofuran (THF), methoxyethanol, ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone , Esters such as ethyl formate, propyl formate, methyl acetate, ethyl acetate, propyl acetate, butyl acetate, methyl propionate, diethyl ether, dimethoxyethane, tetrahydride Furan, dioxolane, dioxane or ether solvents such as anisole,, N, N-dimethylformamide, there are dimethyl sulfoxide and the like. Among these, ketone solvents, ester solvents, ether solvents, or halogenated hydrocarbon solvents are preferable, and these can be used alone or as a mixed solvent of two or more. In addition, about the solvent used for a coating liquid, the same solvent can be used also for the electric charge transport layer (3) mentioned later.

  The electrophotographic photoreceptor of the present invention contains an indoline compound represented by the following general formula (II) as a charge transport agent.

In the general formula (II), R _{3 to} R ₆ are each independently a hydrogen atom, a halogen atom, an optionally substituted alkyl group having 1 to 6 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms. Represents. Moreover, in said general formula (II), R < ₃ > -R < ₆ > is respectively independently a hydrogen atom, a halogen atom, the C1-C4 alkyl group which may have a substituent, or C1-C4. More preferably, it represents an alkoxy group. Specific examples of R _{3 to} R ₆ are not limited to these, but examples include a methyl group, an ethyl group, an n-butyl group, a methoxy group, and an ethoxy group.

  The charge transfer agent represented by the general formula (II) has high photoresponsiveness, has good compatibility with the asymmetric disazo pigment represented by the general formula (I), and has high environmental resistance. It can provide a body.

  Among the indoline compounds represented by the general formula (II), indoline compounds represented by the following chemical formulas (IIa) to (IIe) are particularly preferable because they have good compatibility with the asymmetric disazo pigment represented by the above general formula (I).

  Specific compounds are shown below, but the present invention is not limited to them.

  In this case, the content of the compound represented by the general formula (II) in the charge transport layer (3) is preferably 0.3 to 2.0 parts by weight with respect to 1 part by weight of the binder resin. . If the content of this compound is less than 0.3 parts by weight, the electrical characteristics deteriorate, for example, the residual potential increases. On the other hand, when the amount is more than 2.0 parts by weight, mechanical properties such as wear resistance are deteriorated.

  Furthermore, the compound represented by the general formula (II) and other charge transporting agents can be mixed and used. In this case, the content ratio of the compound represented by the general formula (II) and the other compound is the compound represented by the general formula (II): other compound = 50: 50 to 95: 5, preferably 70:30. A range of ~ 95: 5 is preferred.

  The film thickness of the charge transport layer (3) is 3 to 50 μm, preferably 10 to 40 μm.

  Other charge transport agents include polyvinyl carbazole, halogenated polyvinyl carbazole, polyvinyl pyrene, polyvinyl indoloquinoxaline, polyvinyl benzothiophene, polyvinyl anthracene, polyvinyl acridine, polyvinyl pyrazoline, polyacetylene, polythiophene, polypyrrole, polyphenylene, polyphenylene vinylene, poly Conductive polymer compounds such as isothianaphthene, polyaniline, polydiacetylene, polyheptadiene, polypyridinediyl, polyquinoline, polyphenylene sulfide, polyferrocenylene, polyperinaphthylene, and polyphthalocyanine can be used. Further, as a low molecular compound, trinitrofluorenone, tetracyanoethylene, tetracyanoquinodimethane, quinone, diphenoquinone, naphthoquinone, anthraquinone and derivatives thereof, polycyclic aromatic compounds such as anthracene, pyrene, phenanthrene, indole, carbazole, Nitrogen-containing heterocyclic compounds such as imidazole, fluorenone, fluorene, oxadiazole, oxazole, pyrazoline, hydrazone, triphenylmethane, triphenylamine, enamine, stilbene and the like can be used. Further, a polymer solid electrolyte in which a polymer compound such as polyethylene oxide, polypropylene oxide, polyacrylonitrile, polymethacrylic acid or the like is doped with a metal ion such as Li ion can also be used. Furthermore, an organic charge transport complex formed of an electron donating compound typified by tetrathiafulvalene-tetracyanoquinodimethane and an electron accepting compound can also be used. Desired photoreceptor characteristics can be obtained by mixing and adding the above compounds.

  In the coating solution for producing the electrophotographic photosensitive member of the present invention, an antioxidant, an ultraviolet absorber, a radical scavenger, a softener, a curing agent, a crosslinking agent, etc. are added as long as the characteristics are not impaired. The characteristics, durability, and mechanical properties of the electrophotographic photosensitive member can be improved. In particular, the antioxidant is useful because it contributes to improving the durability of the electrophotographic photoreceptor.

  The antioxidant added to the photosensitive layer (4) is preferably an amine-based antioxidant, for example, α, α ′ (tetrabenzyl) diamino-P-xylene, N-phenyl-1-naphthylamine, N-phenyl- N'-isopropyl-p-phenylenediamine, N, N-diethyl-p-phenylenediamine, N-phenyl-N'-ethyl-2-methyl-p-phenylenediamine, N-ethyl-N-hydroxyethyl-p- Phenylenediamine, alkylated diphenylamine, N, N′-diphenyl-p-phenylenediamine, N, N′-diallyl-p-phenylenediamine, N-phenyl-1,3-dimethylbutyl-p-phenylenediamine, 4,4 '-Dioctyl-diphenylamine, 4,4'-dioctyl-diphenylamine, 6-ethoxy-2,2, 4-trimethyl-1,2-dihydroquinoline, 2,2,4-trimethyl-1,2-dihydroquinoline, N-phenyl-β-naphthylamine, N, N′-di-2-naphthyl-p-phenylenediamine, etc. Can be mentioned.

  Phenol antioxidants include 2,6-di-tert-butylphenol, 2,6-di-tert-4-methoxyphenol, 2-tert-butyl-4-methoxyphenol, 2,4-dimethyl-6-tert. -Butylphenol, 2,6-di-tert-butyl-4-methylphenol, butylated hydroxyanisole, stearyl-propionate-β- (3,5-di-tert-butyl-4-hydroxyphenyl), α-tocopherol, monophenols such as β-tocopherol, n-octadecyl-3- (3′-5′-di-tert-butyl-4′-hydroxyphenyl) propionate, 2,2′-methylenebis (6-tert-butyl-4) -Methylphenol), 4.4'-butylidene-bis- (3-methyl-6-tert-butyl) Enol), 4,4′-thiobis (6-tert-butyl-3-methylphenol), 1,1,3-tris (2-methyl-4-hydroxy-5-tert-butylphenyl) butane, 1,3 , 5-trimethyl-2,4,6-tris (3,5-di-tert-butyl-4-hydroxybenzyl) benzene, tetrakis [methylene-3 (3,5-di-tert-butyl-4-hydroxyphenyl) ) Propionate] Polyphenols such as methane are preferred.

Sulfuric antioxidants are dilauryl-3,3-thiodipropionate, ditridecyl-3,3-thiodipropionate, dimyristyl-3,3-thiodipropionate, distearyl-3,3-thiodipropioate. Lauryl stearyl-3,3-thiopropionate, bis [2-methyl-4- (3-n-alkylC12-C14) thiopropionate) -5-t-butylphenyl] sulfide, pentaerythritol tetra (Β-lauryl-thiopropionate) ester, 2-mercaptobenzimidazole, 2-mercapto-6-methylbenzimidazole and the like can be mentioned.
One or two or more antioxidants can be simultaneously contained in the photosensitive layer (4).

  Ultraviolet absorbers include 2- (5-methyl-2-hydroxyphenyl) benzotriazole, 2- [2-hydroxy-3,5-bis (α, α-dimethylbenzyl) phenyl] -2H-benzotriazole, 2- (3,5-di-tert-butyl-2-hydroxyphenyl) benzotriazole, 2- (3-tert-butyl-5-methyl-2-hydroxyphenyl) -5-chlorobenzotriazole, 2- (3,5 -Di-tert-butyl-2-hydroxyphenyl) -5-chlorobenzotriazole, 2- (3,5-di-tert-amyl-2-hydroxyphenyl) benzotriazole, 2- (2'-hydroxy-5 ' -Tert-octylphenyl) benzotriazoles such as benzotriazole, phenyl salicylate, salicylic acid-p-te Salicylic acid series such as rt-butylphenyl and salicylic acid-p-octylphenyl are preferred, and benzotriazole ultraviolet absorbers are particularly preferred. One or more ultraviolet absorbers can be simultaneously contained in the photosensitive layer.

  The addition amount of the amine-based antioxidant, phenol-based antioxidant, and sulfur-based antioxidant added to the electrophotographic photoreceptor of the present invention is the same as that of the binder resin for the amine-based antioxidant and the phenol-based antioxidant. It is preferable that the amount is 1 to 20% by weight and 0.1 to 5% by weight for sulfur-based antioxidants. On the other hand, the addition amount of the ultraviolet absorber is also preferably 1 to 20% by weight with respect to the binder resin.

  In addition, the photosensitive layer (4) is composed of an organic thin film such as polyvinyl formal resin, polycarbonate resin, fluorine resin, polyurethane resin, silicone resin, or a siloxane structure formed from a hydrolyzate of a silane coupling agent. A surface protective layer (protective layer) may be provided by forming a thin film. In that case, the durability of the electrophotographic photosensitive member is improved, which is preferable. This surface protective layer may be provided in order to improve functions other than the durability improvement. The film thickness of the surface protective layer is suitably from 0.1 to 20 μm.

<Electrophotographic device>
An electrophotographic apparatus on which the electrophotographic photosensitive member of the present invention is mounted performs image formation by at least a commonly used method such as a charging step, an exposure step, a development step, and a transfer step, and realizes these steps. Have means for.
Specifically, the charging method may be any of a contact type such as a brush or a roller, or a non-contact type such as a scorotron or a corotron, and may be a positive or negative charged charge.
The exposure method may be either LED or LD.
The development method may be two-component, one-component, or magnetic / non-magnetic.
The transfer system may be a roller, a belt, or the like.
As the cleaning method, blade cleaning, brush cleaning, a charging unit or a developing unit may be used as a cleaning process.
Further, a method in which the cleaning process and the charge removal process are omitted may be used.

Next, the electrophotographic apparatus of the present invention will be described. FIG. 2 is a schematic configuration diagram of the electrophotographic apparatus of the present invention.
Reference numeral 11 denotes an electrophotographic photosensitive member rotated in the direction of an arrow in the figure, and a charging member 12 serving as a charging unit is provided in contact with the electrophotographic photosensitive member 11.
The charging member 12 is supplied with a voltage from a power source 13 and uniformly charges the surface of the electrophotographic photosensitive member 11 to a predetermined potential.

  Around the electrophotographic photosensitive member 11, an exposure device 14 as an exposure unit, a developing device 15 as a developing unit, a transfer device 16 as a transfer unit, and a cleaning device are sequentially arranged along the rotation direction of the electrophotographic photosensitive member 11. 17 is arranged. In addition, a fixing device 19 is disposed downstream of the transfer device 16 and the electrophotographic photosensitive member 11 in the conveying direction of the recording medium (recording paper). Note that a static eliminator is not provided.

The exposure device 14 forms an electrostatic latent image by exposing the surface of the electrophotographic photosensitive member 11 uniformly charged by the charging device 12 imagewise.
The electrostatic latent image is carried on the surface of the electrophotographic photosensitive member 11 and moves to a position facing the developing device 15 and is visualized by toner stored in the developing device 15, and the toner image is visualized by the toner. 11 is formed.
This toner image is carried on the surface of the electrophotographic photosensitive member 11 while moving to a position facing the transfer device 16, and is recorded on a recording paper that is a recording medium sandwiched between the electrophotographic photosensitive member 11 and the transfer device 16. Transcribed.
The recording paper having the transferred toner image is conveyed to the fixing device 19, and the toner image is fixed on the recording paper by heat and pressure.
In addition, the electrophotographic photosensitive member 11 after the toner image has been transferred is subjected to a series of electrophotographic image forming processes after the transfer residual toner and the like are removed by the cleaning device 17.
In the case of repeatedly forming an image, an image forming process of an electrophotographic method starting from a charging step by the charging device 12 is performed again.

  At this time, it is preferable that the time required from the start of exposure of the surface of the electrophotographic photoreceptor 11 by the exposure device 14 to the end of the toner image formation by the developing device 15 is 100 milliseconds or less. That is, the electrophotographic photosensitive member on the line connecting the center of the developing roller of the developing device 15 and the center of the electrophotographic photosensitive member 11 in FIG. 2 from the position where the light emitted from the exposure device 14 reaches the electrophotographic photosensitive member 11. The time required for the electrophotographic photosensitive member 11 to rotate to the developing position which is the surface of the body 11 is preferably 100 milliseconds or less. By being 100 ms or less, it is possible to cope with a process in which the diameter of the electrophotographic photosensitive member is reduced and the peripheral speed is increased along with the downsizing and speeding up of the electrophotographic apparatus.

  The example shown in FIG. 2 is a mode including a single electrophotographic photosensitive member, a charging unit, a developing unit, and a transfer unit. However, the present invention is not limited to such a mode. Correspondingly, a so-called tandem type color electrophotographic apparatus provided with four each may be used.

The example shown in FIG. 2 is a transfer system in which a toner image is directly transferred from the electrophotographic photoreceptor 11 to a recording medium. However, the present invention is not limited to such a transfer system, and an intermediate transfer using an intermediate transfer body. It may be a method.
In other words, the transfer means for transferring the toner image carried on the electrophotographic photosensitive member to the recording medium may include a primary transfer portion, an intermediate transfer member, and a secondary transfer portion.

The intermediate transfer method will be described in more detail. For example, when the above-described developing unit forms one toner image, the toner image carried on the electrophotographic photosensitive member is conveyed to a position facing the primary transfer unit. Then, the image is primarily transferred to an intermediate transfer member of a well-known and conventional form such as a belt shape. Next, the toner image primarily transferred onto the intermediate transfer member is conveyed to a position facing the secondary transfer portion while being carried on the surface of the intermediate transfer member, and then secondarily transferred onto the recording medium. Here, both the primary transfer portion and the secondary transfer portion can adopt a well-known and commonly used transfer method. For example, a toner image can be transferred by arranging a transfer roller and applying a predetermined transfer bias. it can.
Further, at this time, when the developing means forms four color toner images corresponding to each of YMCK as in the above-described tandem type color electrophotographic apparatus, the predetermined position on the intermediate transfer member. In addition, primary transfer is performed for each color so that toner images of four colors are stacked. Next, the four-color toner images that are primarily transferred and laminated on the intermediate transfer member are conveyed to a position facing the secondary transfer unit while being supported on the surface of the intermediate transfer member, and then are recorded on the recording medium. Secondary transfer is performed at once.

<Process cartridge for electrophotographic apparatus>
An electrophotographic process cartridge comprising one or more means selected from the above-described charging means, exposure means, developing means, cleaning means, and transfer means, and an electrophotographic photosensitive member is provided. It can be attached / removed integrally with the apparatus, and the exchange operation can be simplified.

  Hereinafter, examples of the electrophotographic photosensitive member according to the present invention will be described in detail together with experimental examples and comparative examples.

Example 1
As a conductive support, on a cylindrical drum made of aluminum with a diameter of 30 mm, an alkyd resin (Beckolite M-6401-50 manufactured by Dainippon Ink and Chemicals) and an amino resin (Super Becamine G-821-60 Dainippon Ink) (Chemical Industry Co., Ltd.) was mixed at a weight ratio of 65:35 to prepare a mixed resin. Further, the mixed resin and titanium oxide (CR-EL Ishihara Sangyo Co., Ltd.) were mixed at a weight ratio of 1: 3 and dissolved in methyl ethyl ketone to form an undercoat layer having a thickness of 1.5 μm as a coating solution.

  Next, 30 g of the disazo pigment powder represented by the following chemical formula (Ia) is added to a solution obtained by dissolving 10 g of polyvinyl butyral resin (BH-5 Sekisui Chemical Co., Ltd.) in 500 ml of glass beads and methyl ethyl ketone, and 20 times with a sand mill disperser. After time dispersion, the resulting dispersion was filtered to remove the glass beads, and a charge generation layer coating solution was prepared. This was dip-coated on the undercoat layer and dried to form a charge generation layer having a thickness of 0.2 μm.

  Next, a polycarbonate resin (Panlite TS2050 manufactured by Teijin Chemicals Ltd.) as a binder resin, a compound represented by the chemical formula (IIc) (described in paragraph [0069]), and a phenolic antioxidant as a charge transport agent 2.6-di-t-4 methylphenol was prepared at a weight ratio of 1.0: 1.0: 0.05 and dissolved in tetrahydrofuran to prepare a charge transport layer coating solution. The electroconductive support having the charge generation layer formed thereon is dip-coated in the charge transport layer coating solution and dried at 120 ° C. for 60 minutes to form a charge transport layer having a thickness of 25.0 μm. Produced.

(Example 2)
An electrophotographic photosensitive member was produced in the same manner as in Example 1 except that the charge transfer agent used in Example 1 was replaced with the charge transfer agent represented by the chemical formula (IIa) (described in paragraph [0067]). did.

(Example 3)
An electrophotographic photosensitive member was produced in the same manner as in Example 1 except that the charge transfer agent used in Example 1 was replaced with the charge transfer agent represented by the chemical formula (IIb) (described in paragraph [0068]). did.

Example 4
An electrophotographic photosensitive member was produced in the same manner as in Example 1 except that the charge transfer agent used in Example 1 was replaced with the charge transfer agent represented by the chemical formula (IId) (described in paragraph [0070]). did.

(Example 5)
An electrophotographic photosensitive member was produced in the same manner as in Example 1 except that the charge transfer agent used in Example 1 was replaced with the charge transfer agent represented by the chemical formula (IIe) (described in paragraph [0071]). did.

(Example 6)
An electrophotographic photosensitive member was produced in the same manner as in Example 1 except that the disazo pigment used in Example 1 was replaced with a disazo pigment represented by the following chemical formula (Ib).

(Example 7)
An electrophotographic photosensitive member was produced in the same manner as in Example 1 except that the disazo pigment used in Example 1 was replaced with a disazo pigment represented by the following chemical formula (Ic).

(Example 8)
Instead of the phenolic antioxidant 2.6-di-tert-butyl-4-methylphenol used in Example 1, the sulfur-based antioxidant distearyl 3,3′thiodipropionate (Semilyzer TPS Electrophotographic photosensitive member in the same manner as in Example 1 except that the ratio (weight ratio) of binder resin: charge transfer agent: sulfur-based antioxidant was changed to 1: 1: 0.01. Was made.

Example 9
Instead of the phenolic antioxidant 2.6-di-tert-butyl-4-methylphenol used in Example 1, the ultraviolet absorber 2- (2-hydroxy-5-methylphenyl) benzotriazole (Tinuvin) -P Geigy) was used to produce an electrophotographic photosensitive member in the same manner as in Example 1.

(Example 10)
Instead of the phenolic antioxidant 2.6-di-tert-butyl-4-methylphenol used in Example 1, an amine antioxidant α, α ′-(tetrabenzyl) diamino-P-xylene Otherwise, an electrophotographic photosensitive member was produced in the same manner as in Example 1.

(Example 11)
In addition to the composition of the charge transport layer used in Example 1, sulfur-based antioxidant distearyl 3,3′thiodipropionate and ultraviolet absorber 2- (2-hydroxy-5-methylphenyl) benzotriazole In addition, the ratio (weight ratio) of binder resin: charge transport agent: phenolic antioxidant: sulfuric antioxidant: UV absorber is 1: 1: 0.05: 0.01: 0.05. A photoconductor was prepared.

(Comparative Example 1)
An electrophotographic photosensitive member was produced in the same manner as in Example 1 except that a charge transporting agent represented by the following chemical formula (A) was used instead of the charge transporting agent used in Example 1.

(Comparative Example 2)
An electrophotographic photosensitive member was produced in the same manner as in Example 1 except that a charge transporting agent represented by the following chemical formula (B) was used instead of the charge transporting agent used in Example 1.

(Comparative Example 3)
An electrophotographic photosensitive member was produced in the same manner as in Example 1 except that a charge transporting agent represented by the following chemical formula (C) was used instead of the charge transporting agent used in Example 1.

(Comparative Example 4)
An electrophotographic photosensitive member was produced in the same manner as in Example 1 except that instead of the disazo pigment used in Example 1, the perylene pigment represented by the following chemical formula (D) was used.

(Comparative Example 5)
An electrophotographic photosensitive member was produced in the same manner as in Example 1 except that instead of the disazo pigment used in Example 1, the disazo pigment represented by the following chemical formula (E) was used.

(Experimental example 1)
An electrophotographic photosensitive member was produced in the same manner as in Example 1 except that the phenolic antioxidant used in Example 1 was not added.

Electrophotographic photoreceptor evaluation <Evaluation of electrical characteristics with a simple measuring instrument>
Using the photosensitive drum evaluation device (dynamic mode measurement) for the function-separated electrophotographic photosensitive member produced in Examples 1 to 11 and Comparative Examples 1 to 5 and Experimental Example 1, the electrophotographic characteristics were evaluated under the following conditions. did.

Using an electrophotographic photosensitive member evaluation apparatus (manufactured by Yamanashi Denshi Kogyo Co., Ltd.), the electrophotographic photosensitive member produced in Examples 1 to 11, Comparative Examples 1 to 5, and Experimental Example 1 is an environment having a temperature of 23 ° C. and humidity of 50% Below (N / N), the surface potential (V0) of the electrophotographic photosensitive member when a discharge current of 25 μA is applied to the electrophotographic photosensitive member by the scorotron method is measured. Thereafter, the discharge current is adjusted so that the surface potential becomes −700 V, and the exposure energy amount when the surface potential is attenuated to ½ (−350 V) by irradiation with a semiconductor laser having a wavelength of 650 nm: the half exposure energy amount (E1 / 2) was measured. Further, the surface potential of the electrophotographic photoreceptor when irradiated with an exposure energy of 1.0 μJ / cm ^{2 was} defined as a residual potential (VL).

The temperature and humidity conditions of the above measurement conditions are changed to an environment with a temperature of 10 ° C. and a humidity of 10% (L / L), and an environment with a temperature of 30 ° C. and a humidity of 80% (H / H). The characteristics were evaluated, and the surface potential (V0), exposure energy (E1 / 2), and residual potential (VL) were measured. Further, as an endurance test, the electrophotographic photosensitive member was charged, exposed, and neutralized in an N / N environment, and 10,000 cycles were repeated. The surface potential (VO), half-exposure energy (E1 / 2), and residual potential (VL) of the electrophotographic photoreceptor after one cycle and 10,000 cycles were measured. For neutralization, an LED (20 μW) having a wavelength of 660 nm was used. The drum rotation speed of the electrophotographic photosensitive member was 100 rpm, and the time from when the laser beam was irradiated until the potential was measured (movement time from the exposure position to the measurement position) was 0.06 seconds. The potential measurement position coincides with the development position in the electrophotographic apparatus. For example, in the case of an electrophotographic apparatus as shown in FIG. 2, the center of the electrophotographic photoreceptor 11 and the center of the developing roller of the developing apparatus 15 are provided. The surface of the electrophotographic photosensitive member 11 on the line connecting the two is the development position.
The results are shown in Table 2.

<Photoresponsiveness evaluation>
Using an electrophotographic photosensitive member evaluation apparatus (manufactured by Yamanashi Denshi Kogyo Co., Ltd.), the electrophotographic photosensitive member produced by the experimental examples, examples, and comparative examples is irradiated with a light amount 5 times the half-exposure amount. The surface potential at the development position when the time to reach the temperature was changed to 100 ms, 50 ms, and 30 ms was evaluated as photoresponsiveness (−V). The results are shown in Table 3. The development position (potential measurement position) is the same as in the above-described electrical characteristic evaluation.

<Image evaluation>
The image was confirmed by changing the transfer current using a Ricoh CX-411 color printer. A solid black image was printed in the first cycle, and the afterimage (ghost) appearing on the subsequent halftone was evaluated in an environment of 23 ° C. and 50% RH. However, the erase exposure equipment equipped in the process was excluded and evaluated. The results are shown in Table 4. Note that no afterimage generation was indicated by ○, afterimage generation was indicated by Δ, and strong afterimage generation was indicated by ×.

The electrophotographic photosensitive member is preferably as the charging property is higher, and the smaller the E1 / 2 is, the higher the photosensitive member is, and as a practical level, E1 / 2 is preferably 0.15 μJ / cm ² or less. VL is 100 V or less as a practical range, and if it is more than that, it causes a problem that the image density is lowered. The results of this evaluation are discussed below.

As is apparent from Table 2, when Examples 1 to 11 and Experimental Example 1 in which the charge generating agent and the charge transporting agent contained in the electrophotographic photosensitive member of the present invention are combined are compared with Comparative Examples 1 to 5, It can be seen that there is little fluctuation in charging (V0) and E1 / 2 residual potential (VL) with respect to environmental fluctuations, and high environmental stability.
Examples 1 to 11 in combination with an aromatic amine-based antioxidant, a phenol-based antioxidant, a sulfur-based antioxidant, and a benzotriazole-based UV absorber, and Experimental Example 1 (the patented charge generator and charge) The combination of the transport agent and the combination containing no additive) was compared with Examples 1 to 11 in which the additive was combined. The decrease in the surface potential (V0) after repeated cycle fatigue (after 10,000 cycles) was within 10V. As can be seen from the graph, the increase in VL is within 20 V, indicating that the durability is better.
It can be seen that the electrophotographic photosensitive member within the scope of the present invention has little environmental fluctuation and excellent durability.

  From Table 3, when Examples 1 to 11 and Experimental Example 1 in which the charge generating agent and the charge transporting agent contained in the electrophotographic photosensitive member of the present invention are combined are compared with Comparative Examples 1 to 5, the present invention clearly becomes clear. It can be seen that the electrophotographic photosensitive member belonging to the range is excellent in light responsiveness with little fluctuation even if the time until reaching the developing unit position after exposure is shortened.

  As is apparent from Table 4, Examples 1 to 11 and Experimental Example 1 were electrophotographic photoreceptors having good afterimages. On the other hand, in Comparative Example 1, a slight afterimage was generated in a strong transfer current, and in Comparative Examples 3 to 5, afterimages were generated and the electrophotographic photosensitive member characteristics were not satisfactory.

  In summary, according to the present invention, an electrophotographic photosensitive member that has little environmental fluctuation, high durability, high photoresponsiveness, and is compatible with a high-speed electrophotographic process, and an electrophotographic apparatus and an electrophotographic method using the same. And a process cartridge for an electrophotographic apparatus.

DESCRIPTION OF SYMBOLS 1 Conductive support body 2 Charge generation layer 3 Charge transport layer 4 Photosensitive layer 11 Electrophotographic photoreceptor 12 Charging member 13 Power supply 14 Exposure device 15 Development device 16 Transfer device 17 Cleaning device 19 Fixing device

JP-A-7-70456 JP 2000-147807 A JP-A-3-75660 Japanese Patent Laid-Open No. 5-6011 JP 11-149170 A

Claims (16)

An electrophotographic photoreceptor having a conductive support and a photosensitive layer provided on the conductive support,
The photosensitive layer includes a binder resin, a charge generator, and a charge transport agent,
The charge generator contains an asymmetric disazo pigment represented by the following general formula (I):
The electrophotographic photoreceptor, wherein the charge transfer agent contains an indoline compound represented by the following general formula (II).

(In the general formula (I), R ₁ and R ₂ each independently represents a substituted or unsubstituted alkyl group, alkoxy group, aryl group, or heterocyclic group, provided that R ₁ and R ₂ are the same as each other. Excluding those that are.)

(In the general formula (II), R _{3 to} R ₆ each independently represents a hydrogen atom, a halogen atom, an alkyl group having 1 to 6 carbon atoms which may have a substituent, or an alkoxy having 1 to 6 carbon atoms. Represents a group.) The electrophotographic photoreceptor according to claim 1, wherein the charge transfer agent contains an indoline compound represented by the following chemical formula (IIa).

The electrophotographic photoreceptor according to claim 1, wherein the charge transfer agent contains an indoline compound represented by the following chemical formula (IIb).

The electrophotographic photoreceptor according to claim 1, wherein the charge transfer agent contains an indoline compound represented by the following chemical formula (IIc).

The electrophotographic photoreceptor according to claim 1, wherein the charge transfer agent contains an indoline compound represented by the following chemical formula (IId).

The electrophotographic photosensitive member according to claim 1, wherein the charge transfer agent contains an indoline compound represented by the following chemical formula (IIe).

  The electrophotographic photoreceptor according to claim 1, wherein the photosensitive layer comprises a charge generation layer containing the charge generation agent and a charge transport layer containing the charge transfer agent.   The electrophotographic photosensitive member according to claim 7, wherein the charge transport layer contains a phenol-based antioxidant.   The electrophotographic photosensitive member according to claim 7, wherein the charge transport layer contains an amine-based antioxidant.   The electrophotographic photosensitive member according to claim 7, wherein the charge transport layer contains a sulfur-based antioxidant.   The electrophotographic photosensitive member according to claim 7, wherein the charge transport layer contains a benzotriazole-based ultraviolet absorber. An electrophotographic photoreceptor according to any one of claims 1 to 11,
Charging means for charging the surface of the electrophotographic photosensitive member;
Exposure means for forming an electrostatic latent image on the surface of the charged electrophotographic photosensitive member;
Developing means for visualizing the electrostatic latent image with toner to form a toner image;
Transfer means for transferring the toner image onto a recording medium,
An electrophotographic apparatus characterized by having no static eliminating means for neutralizing the electrophotographic photosensitive member.   13. The electrophotographic apparatus according to claim 12, wherein the electrophotographic apparatus is a tandem type having a plurality of the electrophotographic photosensitive member, the charging unit, the developing unit, and the transfer unit. The developing unit forms one or more toner images;
The transfer means includes a primary transfer portion, an intermediate transfer member, and a secondary transfer portion,
The primary transfer unit primarily transfers the toner image on the electrophotographic photosensitive member onto the intermediate transfer member,
The secondary transfer unit secondarily transfers the toner image on the intermediate transfer member onto a recording medium,
When the developing unit forms two or more toner images,
The primary transfer unit performs primary transfer so that the two or more toner images are stacked on the intermediate transfer member,
14. The electrophotographic apparatus according to claim 12, wherein the secondary transfer unit collectively transfers two or more toner images stacked on the intermediate transfer member onto the recording medium. A charging step for charging the electrophotographic photosensitive member;
An exposure step of forming an electrostatic latent image on the surface of the charged electrophotographic photosensitive member;
A developing step of visualizing the electrostatic latent image with toner to form a toner image;
A transfer step of transferring the toner image onto a recording medium,
The electrophotographic photoreceptor is the electrophotographic photoreceptor according to any one of claims 1 to 11,
An electrophotographic method, wherein a time required from the exposure step to the development step is 100 milliseconds or less. One or more means selected from charging means, exposure means, developing means, cleaning means, and transfer means;
An electrophotographic photosensitive member according to any one of claims 1 to 11, comprising a process cartridge for an electrophotographic apparatus.

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