JP2009276448A - Electrophotographic photoreceptor and image forming apparatus using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrophotographic photoreceptor having a reduced diameter and adaptable to a process at a high peripheral speed, attaining high sensitivity and high responsiveness even in a long wavelength region, stabilizing reproducibility of initial potential and potential after repeated use at high speed, and forming an image of high quality regardless of use environment, and to provide an image forming apparatus using the same. <P>SOLUTION: This electrophotographic photoreceptor has a photosensitive layer containing at least a charge generating agent, a charge transport agent and binder resin on a support, wherein the charge generating agent is hydroxy gallium phthalocyanine, and the charge transport agent contains triphenylamine-based tristyryl compound. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to an electrophotographic photosensitive member containing hydroxygallium phthalocyanine having a specific crystal form as a charge generating agent and a specific compound as a charge transporting agent, and an image forming apparatus using the electrophotographic photosensitive member.

  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. Further, along with the miniaturization and speeding up of copying machines and printers, processes have been adopted in which the diameter of the photoreceptor is reduced and the peripheral speed is high. Therefore, the electrophotographic photosensitive member generally uses a charge generating agent having sensitivity in a long wavelength region. As such a charge generating agent, a phthalocyanine pigment is used. It is known that the sensitivity or stability of this phthalocyanine pigment varies depending on the added metal or crystal type. In addition, with the widespread use of personal computers, the usage environment of image forming apparatuses such as printers has also diversified, so that there is an increasing demand for stable images.

  Among the phthalocyanine-based pigments, hydroxygallium phthalocyanine is exemplified as a pigment having sensitivity in a long wavelength region and excellent in repetitive stability. Several crystal forms of hydroxygaliuphthalocyanine have been introduced. Among them, Bragg angles (2θ) 7.5 °, 9.9 °, 12.5 °, 16.3 °, 18.6 °, Those having diffraction peaks at 25.1 ° and 28.3 ° are said to be excellent in repeated stability. However, when this hydroxygallium phthalocyanine is used in a high-speed process, the potential characteristics of the photoreceptor after repeated use are deteriorated, resulting in fogging, black streaks, density unevenness and the like in the obtained image. When hydroxygallium phthalocyanine is used in a high-speed process, if the photoresponsiveness is not sufficient, a charge remains in the photosensitive layer, which may cause fogging, black streaks, density unevenness, etc. in the next electrophotographic process. Become. Moreover, as a charge transport agent, it is necessary to have a high charge transport capability, and the combination of a charge generation agent and a charge transport agent is important (for example, refer patent document 1).

  Therefore, an electrophotographic photosensitive member having sensitivity in a long wavelength region, high responsiveness, and stable reproducibility of electrophotographic characteristics, particularly initial potential and potential after repeated use, even when repeatedly used at high speed. It has been demanded. Even if a charge generating agent having high charge generation efficiency is used, sufficient sensitivity cannot be obtained if the compatibility with the charge transporting agent is poor, and it is also high in various usage environments from high temperature and high humidity to low temperature and low humidity. Quality image is not obtained. 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.

Japanese Patent Laid-Open No. 1-106069

  This invention is made | formed in view of this present condition, and makes it a subject to solve the said various problems in the past and to achieve the following objectives. That is, the present invention can cope with a process of reducing the diameter of an electrophotographic photosensitive member and a process having a high peripheral speed, is highly sensitive and responsive in a long wavelength region, and repeats with an initial potential even when used repeatedly at high speed. To provide an electrophotographic photoreceptor capable of forming a high-quality image without being restricted by the use environment, and an image forming apparatus using the electrophotographic photoreceptor, in which the potential reproducibility after use is stable. Objective.

  As a result of intensive studies to solve the above problems, the present inventors have used hydroxygallium phthalocyanine exhibiting a specific X-ray diffraction peak as a charge generating agent and combined with a specific charge transporting agent. However, it has been found that the conventional problems can be solved.

The present invention is based on the above findings by the present inventors, and means for solving the above problems are as follows.
<1> In an electrophotographic photoreceptor having a support and a photosensitive layer containing at least a charge generator, a charge transport agent, and a binder resin on the support,
The charge generating agent in the photosensitive layer is hydroxygallium phthalocyanine;
An electrophotographic photoreceptor, wherein the charge transfer agent contains a compound represented by the following general formula (I).
However, the general formula (I), R ¹ ~R ² has each independently a hydrogen atom, a halogen atom, an optionally substituted alkyl group having 1 to 6 carbon atoms, and the substituents Any one of the C1-C6 alkoxy groups which may be present.
<2> The electrophotographic photosensitive member according to <1>, wherein the charge transfer agent contains a compound represented by the following structural formula (Ia).
<3> The electrophotographic photosensitive member according to <1>, wherein the charge transfer agent contains a compound represented by the following structural formula (Ib).
<4> The electrophotographic photosensitive member according to <1>, wherein the charge transport agent contains a compound represented by the following structural formula (Ic).
<5> The electrophotographic photosensitive member according to <1>, wherein the charge transfer agent contains a compound represented by the following structural formula (Id).
<6> Hydroxygallium phthalocyanine is a Bragg angle (2θ ± 0.2 °) of 7.5 °, 9.9 °, 12.5 °, 16.3 ° in an X-ray diffraction spectrum using CuKα as a radiation source. The electrophotographic photosensitive member according to any one of <1> to <5>, which has diffraction peaks at 18.6 °, 25.1 °, and 28.3 °.
<7> The electrophotographic photosensitive member according to any one of <1> to <6>, wherein the photosensitive layer contains a hindered phenol-based antioxidant.
<8> The electrophotographic photosensitive member according to any one of <1> to <7>, wherein the photosensitive layer contains an amine-based antioxidant.
<9> The electrophotographic photosensitive member according to any one of <1> to <8>, wherein the photosensitive layer contains a sulfur-based antioxidant.
<10> The electrophotographic photosensitive member according to any one of <1> to <9>, wherein the photosensitive layer contains a benzotriazole ultraviolet absorber.
<11> An electrophotographic photosensitive member, charging means for charging the surface of the electrophotographic photosensitive member, exposure means for exposing the charged electrophotographic photosensitive member surface to form an electrostatic latent image, and the electrostatic latent image An image forming apparatus having at least developing means for developing a visible image by developing a toner and a transfer means for transferring the visible image to a recording medium,
An electrophotographic photosensitive member according to any one of <1> to <10>, wherein the electrophotographic photosensitive member is an image forming apparatus.

  According to the present invention, the conventional problems can be solved, the object can be achieved, the diameter of the electrophotographic photosensitive member can be reduced, and a process with a high peripheral speed can be achieved. An electrophotographic photosensitive member that is highly responsive and has stable reproducibility of the initial potential and potential after repeated use, even when used repeatedly at high speed, and can form high-quality images without being restricted by the use environment. And an image forming apparatus using the electrophotographic photosensitive member.

(Electrophotographic photoreceptor)
The electrophotographic photosensitive member of the present invention has a support and a photosensitive layer on the support, and further includes other layers as necessary.

<Support>
The support is not particularly limited as long as it exhibits conductivity, and can be appropriately selected according to the purpose. For example, aluminum, brass, stainless steel, nickel, chromium, titanium, gold, silver, copper , Simple metals such as tin, platinum, molybdenum, and indium, and processed bodies of these alloys.
The shape of the support is not particularly limited as long as it is a flexible shape, and can be appropriately selected according to the purpose, and examples thereof include a sheet shape, a film shape, and a belt shape. Either of these may be used.
There is no restriction | limiting in particular as a diameter of the said support body, Although it can select suitably according to the objective, 60 mm or less is preferable and 30 mm or less is more preferable.
The volume resistance of the support is not particularly limited as long as it is 10 ¹⁰ Ω · cm or less, and can be appropriately selected according to the purpose.

Among the above supports, aluminum alloys such as JIS 3000, JIS 5000, and JIS 6000 are preferable.
In addition, a support formed by a general method such as an EI (Extension Ironing) method, an ED (Extension Drawing) method, a DI (Drawing Ironing) method, or an II (Impact Ironing) method is preferable.
Further, the support may be a support obtained by subjecting the surface of the support to surface cutting processing such as diamond cutting, polishing, anodizing treatment, or the like, or support such as a non-cutting tube that does not perform such processing or processing. It may be the body.

When a resin is used as the substrate of the support, a conductive agent such as metal powder or conductive carbon can be contained in the resin, and a conductive resin can also be used as the substrate forming resin.
Furthermore, when glass is used as the substrate of the support, the surface of the glass may be coated with tin oxide, indium oxide, or aluminum iodide to provide conductivity.

  A resin layer may be formed on the support. The resin layer has an adhesion improving function, a barrier function for preventing an inflow current from the aluminum tube, a defect covering function on the surface of the aluminum tube, and the like. 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, and melamine resin are used for the resin layer. be able to. The resin layer may be composed of a single resin or a mixture of two or more resins. Moreover, a metal compound, carbon, silica, resin powder, and the like can be dispersed in the resin layer. Furthermore, various pigments, electron accepting substances, electron donating substances and the like may be included for improving the characteristics.

<Photosensitive layer>
The photosensitive layer contains at least a charge generator, a charge transport agent, and a binder resin, and further contains other components as necessary.

In the first embodiment, the photosensitive layer is a photosensitive layer having a single layer structure containing at least a charge generating agent, a charge transporting agent, and a binder resin (hereinafter also referred to as “single-layer type photosensitive layer”). And other layers as necessary.
In the second embodiment, a photosensitive layer having a structure in which a charge generating layer containing at least a charge generating agent and a charge transporting layer containing at least a charge transporting agent are laminated (hereinafter referred to as “laminated type (function separation type) photosensitivity”). It may also be referred to as a “layer”), and may further include other layers as necessary. In the second embodiment, the charge generation layer and the charge transport layer may be laminated in reverse.

-Layered photosensitive layer-
The laminated photosensitive layer includes a charge generation layer and a charge transport layer, and further includes other layers as necessary.

-Charge generation layer-
The charge generation layer includes at least a charge generation agent, a binder resin (binder resin), and further includes other components as necessary.

--- Charge generator ---
As the charge generating agent, hydroxygallium phthalocyanine is used.
The hydroxygallium phthalocyanine has Bragg angles (2θ ± 0.2 °) of 7.5 °, 9.9 °, 12.5 °, 16.3 °, 18.6 in an X-ray diffraction spectrum using CuKα as a radiation source. It is preferable to have strong diffraction peaks at °, 25.1 °, and 28.3 °.
The content of the hydroxygallium phthalocyanine in the charge generation layer is preferably 0.1 part by mass to 10 parts by mass, more preferably 0.5 part by mass to 5 parts by mass with respect to 1 part by mass of the binder resin. Part by mass to 4 parts by mass are particularly preferred. When the content of the hydroxygallium phthalocyanine in the charge generation layer is less than 0.1 parts by mass, the sensitivity may decrease and a sufficient image density may not be obtained. May decrease and stable quality may not be obtained. On the other hand, when the content of the hydroxygallium phthalocyanine in the charge generation layer is within the particularly preferable range, it is advantageous in terms of electrical characteristics and film formability.
The hydroxygallium phthalocyanine can be synthesized, for example, by the method shown in Synthesis Example 1 described later.

  In addition to the hydroxygallium phthalocyanine, phthalocyanines other than the hydroxygallium phthalocyanine, azo pigments, and the like can be mixed in the charge generation layer in order to obtain an appropriate photosensitivity wavelength and sensitizing action. These are desirable in terms of good sensitivity compatibility. Further, monoazo pigments, bisazo pigments, trisazo pigments, polyazo pigments, indigo pigments, selenium pigments, toluidine pigments, pyrazoline pigments, perylene pigments, quinacridone pigments, pyrylium salts, and the like can also be used.

--- Binder resin ---
The binder resin is not particularly limited and may be appropriately selected depending on the intended purpose. For example, 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, polyallylsulfone resin, silicone resin, ketone resin, polyvinyl butyral resin, polyether resin, phenol resin, EVA (ethylene / vinyl acetate) resin, ACS (active resin) Ronitoriru-chlorinated polyethylene-styrene) resin, ABS (acrylonitrile butadiene styrene) resin, and an epoxy arylate and the like. These may be used individually by 1 type and may use 2 or more types together. It is preferable to use a mixture of resins having different molecular weights in terms of improving hardness and wear resistance. In addition, the said resin can be used also for binder resin contained in the electric charge transport layer mentioned later.

  As the method for forming the charge generation layer, various methods can be used. For example, the hydroxygallium phthalocyanine is used as a charge generator, a binder resin, and, if necessary, a plasticizer, an antioxidant, and a leveling agent. An appropriate amount of an additive such as an agent can be added, and a coating solution dispersed or dissolved in an appropriate solvent can be applied on a support and dried as necessary.

  Examples of the solvent 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; Aromatic hydrocarbons such as toluene and xylene; Chlorine hydrocarbons such as dichloromethane, dichloroethane, chloroform and chlorobenzene; Ethers such as dimethyl ether, diethyl ether, tetrahydrofuran (THF) and methoxyethanol; Acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone Ketones such as ethyl formate, propyl formate, methyl acetate, ethyl acetate, propyl acetate, butyl acetate, methyl propionate, etc .; diethyl ether Dimethoxyethane, tetrahydrofuran, dioxolane, dioxane, ether solvents such as anisole; N, N-dimethylformamide, and dimethyl sulfoxide. These may be used individually by 1 type and may use 2 or more types together. Among these, ketone solvents, ester solvents, ether solvents and halogenated hydrocarbon solvents are preferable. In addition, the said solvent can be used also for the coating liquid of the charge transport layer mentioned later.

As the coating method, known methods such as dip coating, spray coating, bead coating, nozzle coating, spinner coating, and ring coating can be used. Further, drying after coating is performed by heating using an oven or the like. The drying temperature of the charge generation layer is preferably 50 ° C to 160 ° C, more preferably 80 ° C to 140 ° C.
The thickness of the charge generation layer is preferably 0.01 μm to 5 μm, and more preferably 0.1 μm to 2 μm.

-Charge transport layer-
The charge transport layer contains at least a charge transport agent and a binder resin, and further contains other components as necessary.

  The charge transport agent contains a compound represented by the following general formula (I). The charge transfer agent is capable of providing an electrophotographic photosensitive member having a good compatibility with the hydroxygallium phthalocyanine used as the charge generating agent and having high environmental resistance.

In the general formula (I), R ^{1 to} R ² each independently have a hydrogen atom, a halogen atom, an optionally substituted alkyl group having 1 to 6 carbon atoms, and a substituent. Or any one of C1-C6 alkoxy groups.
Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.
Examples of the alkyl group include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, and a hexyl group.
Examples of the alkoxy group include a methoxy group, an ethoxy group, a propoxy group, and a butoxy group.
Examples of the substituent include a halogen atom, a nitro group, a cyano group, an alkyl group such as a methyl group and an ethyl group, an alkoxy group such as a methoxy group and an ethoxy group, an aryloxy group such as a phenoxy group, a phenyl group and a naphthyl group. Aryl groups such as aralkyl groups such as benzyl group and phenethyl group.

As specific examples of the compound represented by the general formula (I), the compounds represented by the following structural formulas (Ia) to (Id) are preferable because of compatibility with the hydroxygallium phthalocyanine used in the present invention. In addition, specific compounds are not limited to these.

  The content of the compound represented by the general formula (I) in the charge transport layer is preferably 0.3 parts by mass to 2.0 parts by mass with respect to 1 part by mass of the binder resin. If the content of the compound represented by the general formula (I) is less than 0.3 parts by mass, the electrical characteristics may deteriorate such as an increase in residual potential. Mechanical properties such as wear may be reduced.

The charge transport agent may contain the compound represented by the general formula (I) and other charge transport agents. There is no restriction | limiting in particular as said other charge transport agent, According to the objective, it can select suitably, For example, a high molecular compound, a low molecular compound, etc. are mentioned.
Examples of the polymer compound include polyvinyl carbazole, halogenated polyvinyl carbazole, polyvinyl pyrene, polyvinyl indoloquinoxaline, polyvinyl benzothiophene, polyvinyl anthracene, polyvinyl acridine, polyvinyl pyrazoline, polyacetylene, polythiophene, polypyrrole, polyphenylene, polyphenylene vinylene, Conductive polymer compounds such as polyisothianaphthene, polyaniline, polydiacetylene, polyheptadiene, polypyridinediyl, polyquinoline, polyphenylene sulfide, polyferrocenylene, polyperinaphthylene, and polyphthalocyanine can be used.
Examples of the low molecular weight compound include trinitrofluorenone, tetracyanoethylene, tetracyanoquinodimethane, quinone, diphenoquinone, naphthoquinone, anthraquinone or derivatives thereof, anthracene, pyrene, phenanthrene, and other polycyclic aromatic compounds; indole, Nitrogen-containing heterocyclic compounds such as carbazole and imidazole; fluorenone, fluorene, oxadiazole, oxazole, pyrazoline, hydrazone, triphenylmethane, triphenylamine, enamine, stilbene and the like can be mentioned.
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 transfer complex formed of an electron donating compound typified by tetrathiafulvalene-tetracyanoquinodimethane and an electron accepting compound can also be used.
These may be used individually by 1 type and may use 2 or more types together.
When the compound represented by the general formula (I) and the other charge transport agent are mixed and used, the content ratio of the compound represented by the general formula (I) and the other charge transport agent is as follows. The compound represented by the general formula (I): other charge transfer agent = 50: 50 to 95: 5 is not particularly limited and may be appropriately selected depending on the intended purpose. A range of ˜95: 5 is preferred.

--- Binder resin ---
As the binder resin, the same binder resin as that contained in the charge generation layer described above can be used. The charge transport layer may also contain a copolymer of a crosslinkable binder resin and a crosslinkable charge transport agent.

As a method for forming the charge transport layer, various methods can be used. For example, the above-described charge transport agent, binder resin, and, if necessary, a plasticizer, an antioxidant, a leveling agent, and the like are added. It can be formed by adding an appropriate amount of an agent, applying a coating solution dissolved or dispersed in a suitable solvent, and drying it as necessary.
As the solvent used in the coating solution, the same coating solution as that used in the charge generation layer described above can be used.
As the coating method, known methods such as dip coating, spray coating, bead coating, nozzle coating, spinner coating, and ring coating can be used. Further, drying after coating is performed by heating using an oven or the like. The drying temperature of the charge transport layer is preferably 50 ° C to 160 ° C, more preferably 80 ° C to 140 ° C.
The thickness of the charge transport layer is preferably 5 μm to 100 μm, and more preferably 15 μm to 40 μm.

-Single layer type photosensitive layer-
The single-layer type photosensitive layer contains at least a charge generator, a charge transport agent, and a binder resin on the support,
The charge generating agent in the photosensitive layer is hydroxygallium phthalocyanine, and the hydroxygallium phthalocyanine has Bragg angles (2θ ± 0.2 °) of 7.5 ° and 9.9 ° in an X-ray diffraction spectrum using CuKα as a radiation source. Having strong diffraction peaks at 12.5 °, 16.3 °, 18.6 °, 25.1 ° and 28.3 °,
The charge transfer agent contains a compound represented by the above general formula (I).

As the charge generation agent and the charge transport agent, the materials mentioned in the charge generation layer and the charge transport layer can be used. Further, as the binder resin, the resins mentioned in the charge generation layer can be used. Examples of other components include plasticizers, fine particles, and various additives.
The content of the charge generating agent is preferably 0.002 parts by mass to 0.2 parts by mass, more preferably 0.005 parts by mass to 0.1 parts by mass, with respect to 1 part by mass of the binder resin. Part by mass to 0.04 part by mass is particularly preferable.
The content of the charge transfer agent is preferably 0.2 parts by weight to 4 parts by weight, more preferably 0.5 parts by weight to 2 parts by weight, with respect to 1 part by weight of the binder resin. Part by mass is particularly preferred.

In the single-layer type photosensitive layer, the charge generator, the binder resin, and the charge transport agent are dissolved or dispersed in a solvent such as tetrahydrofuran, dioxane, dichloroethane, cyclohexanone, toluene, methyl ethyl ketone, acetone, and the like. It can be formed by coating with a spray coat, bead coat, ring coat or the like. If necessary, various additives such as a plasticizer, a leveling agent, an antioxidant and a lubricant can be added.
The thickness of the single-layer type photosensitive layer is not particularly limited and can be appropriately selected according to the purpose, and is preferably 10 μm to 40 μm.

<Other layers>
The other layers are not particularly limited as long as the effects of the present invention are not impaired, and can be appropriately selected according to the purpose. Examples thereof include an undercoat layer and a protective layer.
-Undercoat layer-
In the electrophotographic photoreceptor of the present invention, an undercoat layer can be provided between the support and the photosensitive layer. The undercoat layer generally comprises a resin as a main component, but these resins are resins having a high solvent resistance with respect to a general organic solvent in consideration of applying a photosensitive layer thereon with a solvent. It is preferable. Examples of the resin include water-soluble resins such as polyvinyl alcohol, casein, and sodium polyacrylate, alcohol-soluble resins such as copolymer nylon and methoxymethylated nylon, polyurethane, melamine resin, phenol resin, alkyd-melamine resin, and epoxy. Examples thereof include a curable resin that forms a three-dimensional network structure such as a resin. In order to prevent moire and reduce residual potential, the undercoat layer is added with a fine powder pigment of a metal oxide such as titanium oxide, silica, alumina, zirconium oxide, tin oxide, or indium oxide. be able to.
For the undercoat layer, an anodized layer of Al ₂ O ₃ , an organic material such as polyparaxylylene (parylene), or an inorganic material such as SiO ₂ , SnO ₂ , TiO ₂ , ITO, or CeO ₂ is vacuumed. Those provided by the thin film manufacturing method can also be used favorably. In addition, known ones can be used.
The undercoat layer can be formed using an appropriate solvent and a coating method like the above-described photosensitive layer. Furthermore, a silane coupling agent, a titanium coupling agent, a chromium coupling agent, or the like can be used as the undercoat layer of the present invention.
There is no restriction | limiting in particular in the thickness of the said undercoat layer, According to the objective, it can select suitably, 5 micrometers or less are preferable.

-Protective layer-
In the electrophotographic photosensitive member of the present invention, a protective layer can be provided on the photosensitive layer for the purpose of improving the durability of the electrophotographic photosensitive member and improving other functions. The protective layer contains at least a binder resin and a filler, and further contains other components as necessary. The protective layer is made of an organic thin film such as polyvinyl formal resin, polycarbonate resin, fluororesin, polyurethane resin, or silicone resin, or a thin film made of a siloxane structure formed from a hydrolyzate of a silane coupling agent on the photosensitive layer. It can be provided by forming a film.

In the electrophotographic photoreceptor of the present invention, an antioxidant, an ultraviolet absorber, a radical, and the like are added to each layer such as a charge generation layer, a charge transport layer, an undercoat layer, a protective layer, and a single-layer type photosensitive layer as long as the characteristics are not impaired. A capturing agent, a softening agent, a curing agent, a crosslinking agent, and the like can be added to improve the characteristics, durability, and mechanical properties of the photoreceptor.
Among these, antioxidants and ultraviolet absorbers are particularly useful because they contribute to improving the durability of the photoreceptor when used alone or in combination. Among these, the photosensitive layer preferably contains at least one of a hindered phenol-based antioxidant, an amine-based antioxidant, a sulfur-based antioxidant, and a benzotriazole-based ultraviolet absorber.
Addition of dispersion stabilizers, anti-settling agents, anti-color separation agents, leveling agents, antifoaming agents, thickeners, matting agents, etc. can improve the finished appearance of the photoreceptor and the life of the coating solution. Can do.

  There is no restriction | limiting in particular as said antioxidant, According to the objective, it can select suitably, For example, a hindered phenolic antioxidant, an amine antioxidant, sulfur type antioxidant, etc. are mentioned. These may be used individually by 1 type and may use 2 or more types together.

  There is no restriction | limiting in particular as said hindered phenolic antioxidant, According to the objective, it can select suitably, For example, 2.6-di-tert- butylphenol, 2.6-di-tert-4-methoxy. Phenol, 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, β-tocopherol, n-octadecyl-3- (3′-5′-di-tert-butyl-4′-hydroxyphenyl) ) Monophenols such as propionate; 2.2'-methylenebis (6-tert-butyl-4- Tilphenol), 4.4'-butylidene-bis- (3-methyl-6-tert-butylphenol), 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) Examples thereof include polyphenols such as benzene and tetrakis [methylene-3 (3.5-di-tert-butyl-4-hydroxyphenyl) propionate] methane. These may be used individually by 1 type and may use 2 or more types together.

  The amine-based antioxidant is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include 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-dihydroquino Emissions, 2,2,4-trimethyl-1,2-dihydroquinoline, N- phenyl -β- naphthylamine, N, N'and di-2-naphthyl -p- phenylenediamine. These may be used individually by 1 type and may use 2 or more types together.

  There is no restriction | limiting in particular as said sulfur type antioxidant, According to the objective, it can select suitably, For example, dilauryl-3.3-thiodipropionate, ditridecyl-3.3-thiodipropionate, dimyristyl. -3.3-thiodipropionate, distearyl-3.3-thiodipropionate, laurylstearyl-3.3-thiopropionate, bis [2-methyl-4- (3-n-alkyl (C12 C14) thiopropionate) -5-t-butylphenyl] sulfide, pentaerythritol tetra (β-lauryl-thiopropionate) ester, 2-mercaptobenzimidazole, 2-mercapto-6-methylbenzimidazole, etc. Can be mentioned. These may be used individually by 1 type and may use 2 or more types together.

  The ultraviolet absorber is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof 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) benzotriazo And benzotriazole ultraviolet absorbers such as salicylate; salicylic acid ultraviolet absorbers such as phenyl salicylate, salicylic acid-p-tert-butylphenyl, and salicylic acid-p-octylphenyl. These may be used individually by 1 type and may use 2 or more types together. Among these, benzotriazole ultraviolet absorbers are particularly preferable.

  The amount of the hindered phenol-based antioxidant added is preferably 3% by mass to 20% by mass with respect to the binder resin. Moreover, the addition amount of the amine-based antioxidant is preferably 3% by mass to 20% by mass with respect to the binder resin. The addition amount of the sulfur-based antioxidant is preferably 0.5% by mass to 5% by mass with respect to the binder resin. The addition amount of the ultraviolet absorber is preferably 3% by mass to 20% by mass with respect to the binder resin.

(Image forming device)
The image forming apparatus of the present invention comprises at least an electrophotographic photosensitive member, a charging unit, an exposure unit, a developing unit, and a transfer unit, and a fixing unit, a cleaning unit, and further appropriately selected as necessary. The other means, for example, a static elimination means, a recycling means, a control means, etc. are provided. The charging unit and the exposure unit may be collectively referred to as an electrostatic latent image forming unit.
The image forming method used in the present invention includes at least a charging step, an exposure step, a development step, and a transfer step, and a fixing step, a cleaning step, and other steps appropriately selected as necessary. For example, it includes a static elimination process, a recycling process, a control process, and the like. The charging process and the exposure process may be collectively referred to as an electrostatic latent image forming process.

  The image forming method used in the present invention can be preferably implemented by the image forming apparatus of the present invention, the charging step can be performed by the charging unit, and the exposure step can be performed by the exposing unit. The developing step can be performed by the developing unit, the transferring step can be performed by the transferring unit, the fixing step can be performed by the fixing unit, and the cleaning step can be performed by the cleaning unit. The other steps can be performed by the other means.

-Electrophotographic photoreceptor-
As the electrophotographic photosensitive member, the electrophotographic photosensitive member of the present invention can be used.

-Charging step and charging means-
The charging step is a step of charging the surface of the electrophotographic photosensitive member, and is performed by a charging unit.
The charging means is not particularly limited and may be appropriately selected depending on the purpose.For example, a contact-type charger including a conductive or semiconductive roll, brush, film, rubber blade, Non-contact type chargers using corona discharge such as corotron and scorotron. Further, the charged charge may be positive or negative.

-Exposure process and exposure means-
The exposure (writing) can be performed, for example, by exposing the surface of the electrophotographic photosensitive member imagewise using the exposure unit.
The exposure unit is not particularly limited as long as the surface of the electrophotographic photosensitive member charged by the charging unit can be exposed like an image to be formed, and can be appropriately selected according to the purpose. However, there are various exposure devices such as a copying optical system, a rod lens array system, a laser optical system, a liquid crystal shutter optical system, and an LED optical system.
In the present invention, an optical backside system that performs imagewise exposure from the backside of the electrophotographic photosensitive member may be employed.
As the light source, for example, a light source capable of ensuring high luminance such as a light emitting diode (LED), a semiconductor laser (LD), and electroluminescence (EL) is used.

-Development process and development means-
The developing step is a step of developing the electrostatic latent image with toner to form a visible image.
The visible image can be formed, for example, by developing the electrostatic latent image using toner, and can be performed by the developing unit.
The developing unit is not particularly limited as long as it can be developed using, for example, the toner or the developer, and can be appropriately selected from known ones. For example, the developer is accommodated and the static It is preferable to have at least a developing unit capable of applying the developer to the electrostatic latent image in a contact or non-contact manner.

The developing unit may be a dry developing type, a wet developing type, a single color developing unit, or a multi-color developing unit. For example, a developer having a stirrer for charging the developer by frictional stirring and a rotatable magnet roller is preferable.
The developing method may be any of two components, one component, and magnetic / nonmagnetic.

  In the developing device, for example, the toner and the carrier are mixed and agitated, and the toner is charged by friction at that time, and held on the surface of the rotating magnet roller in a raised state to form a magnetic brush. . Since the magnet roller is disposed in the vicinity of the electrophotographic photosensitive member, a part of the toner constituting the magnetic brush formed on the surface of the magnet roller is electrically attracted to the electrophotographic photosensitive member. Move to the surface of the body. As a result, the electrostatic latent image is developed with the toner, and a visible image is formed with the toner on the surface of the electrophotographic photosensitive member.

-Transfer process and transfer means-
The transfer means is a means for transferring the visible image onto a recording medium. The transfer means can be transferred onto the intermediate transfer body using a method of directly transferring the visible image from the surface of the photoreceptor to the recording medium and an intermediate transfer body. There is a method in which a visual image is first transferred, and then the visible image is secondarily transferred onto the recording medium, and either aspect can be used favorably.
The transfer can be performed, for example, by charging the electrophotographic photosensitive member with the transfer charger using the visible image, and can be performed by the transfer unit. The transfer unit is not particularly limited and can be appropriately selected from known transfer units according to the purpose. For example, a transfer conveyance belt that can simultaneously convey a recording medium can be preferably used. .
The transfer means (the primary transfer means and the secondary transfer means) has at least a transfer charger that peels and charges the visible image formed on the electrophotographic photosensitive member to the recording medium side. Is preferred. There may be one transfer means or two or more transfer means. Examples of the transfer charger include a corona transfer device using corona discharge, a transfer belt, a transfer roller, a pressure transfer roller, and an adhesive transfer device. The recording medium is not particularly limited and can be appropriately selected from known recording media (recording paper).
The transfer charger may be a transfer belt or a transfer roller, but it is preferable to use a contact type such as a transfer belt or transfer roller that generates less ozone. As a voltage / current application method at the time of transfer, either a constant voltage method or a constant current method can be used, but the transfer charge amount can be kept constant, and a constant voltage with excellent stability can be used. The current method is more preferable. As such a transfer unit, a known unit can be used as long as the configuration of the present invention can be satisfied.

-Fixing process and fixing means-
The fixing may be performed each time the visible image transferred to the recording medium is fixed by using a fixing device and transferred to the recording medium for each color toner, or the toner is stacked on each color toner. May be performed simultaneously at the same time.
There is no restriction | limiting in particular as said fixing device, Although it can select suitably according to the objective, A well-known heating-pressing means is suitable. Examples of the heating and pressing means include a combination of a heating roller and a pressure roller, a combination of a heating roller, a pressure roller, and an endless belt. The heating in the heating and pressing means is usually preferably 80 ° C to 200 ° C. In the present invention, for example, a known optical fixing device may be used together with or in place of the fixing step and the fixing unit depending on the purpose.

-Cleaning process and cleaning means-
The cleaning means is not particularly limited as long as it can remove the toner remaining on the electrophotographic photosensitive member, and can be appropriately selected from known cleaners. For example, a magnetic brush cleaner, a static cleaner Preferred examples include an electric brush cleaner, a magnetic roller cleaner, a blade cleaner, a brush cleaner, and a web cleaner.

--- Static elimination process and static elimination means-
The neutralizing means is not particularly limited as long as it can neutralize the electrophotographic photosensitive member, and can be appropriately selected from known neutralizers. For example, fluorescent materials such as a fluorescent lamp, a tungsten lamp, a halogen lamp, a mercury lamp, a sodium lamp, a light emitting diode (LED), a semiconductor laser (LD), and an electroluminescence (EL) can be used. Various types of filters such as a sharp cut filter, a band pass filter, a near infrared cut filter, a dichroic filter, an interference filter, and a color temperature conversion filter can be used to irradiate only light in a desired wavelength range.

--Recycling process and recycling means--
The recycling unit is a step of recycling the toner removed by the cleaning unit to the developing unit, and examples thereof include a known conveying unit.

-Control process and control means-
The control step is a step of controlling each of the steps, and can be suitably performed by a control unit.
The control means is not particularly limited as long as the movement of each means can be controlled, and can be appropriately selected according to the purpose. Examples thereof include devices such as a sequencer and a computer.

  Here, an aspect of the image forming apparatus of the present invention will be described with reference to the drawings. FIG. 4 is a schematic configuration diagram showing an example of the image forming apparatus of the present invention. Reference numeral 11 denotes an electrophotographic photosensitive member, and a charging member 12 is provided in contact therewith. The charging member 12 is supplied with a voltage from a power source 13. Around the electrophotographic photosensitive member 11, an exposure device 14, a developing device 15, a transfer device 16, a cleaning device 17, and a static eliminator 18 are provided. Reference numeral 19 denotes a fixing device. FIG. 5 is an eraseless type image forming apparatus as an example of the image forming apparatus of the present invention, and has the same structure except that the static eliminator 18 in the image forming apparatus of FIG. 4 is not provided. The same reference numerals are given and description thereof is omitted.

4 and 5, the electrophotographic photoreceptor 11 has a photosensitive layer containing at least a charge generator, a charge transport agent, and a binder resin on a support, and the charge generator is hydroxygallium phthalocyanine. In the X-ray diffraction spectrum in which the hydroxygallium phthalocyanine uses CuKα as a radiation source, Bragg angles (2θ ± 0.2 °) of 7.5 °, 9.9 °, 12.5 °, 16.3 °, 18. It has strong diffraction peaks at 6 °, 25.1 ° and 28.3 °, and the charge transfer agent contains a compound represented by the following general formula (I).
However, the general formula (I), R ¹ ~R ² has each independently a hydrogen atom, a halogen atom, an optionally substituted alkyl group having 1 to 6 carbon atoms, and the substituents Any one of the C1-C6 alkoxy groups which may be present.
The electrophotographic photosensitive member 11 has a drum shape, but may be a sheet shape or an endless belt shape.

The charging member 12 is a non-contact roller-shaped charger. By this charger, the photosensitive member is charged.
For the exposure device 14, a light source capable of ensuring high luminance such as a light emitting diode (LED), a semiconductor laser (LD), or electroluminescence (EL) is used. Among these light sources, light emitting diodes and semiconductor lasers have high irradiation energy and are used favorably.
The developing device 15 has at least one developing sleeve. In the developing device 15, toner is used to develop the electrostatic latent image. There are two methods, a one-component method in which development is performed with toner alone and a two-component method in which a two-component developer comprising a toner and a carrier is used. Either method can be used favorably.

The transfer device 16 can be a transfer belt or a transfer roller. The toner image formed on the photoconductor is transferred onto the transfer paper to become an image on the transfer paper.
The light source such as the static elimination lamp 18 is not limited as long as it can neutralize the electrophotographic photosensitive member, and can be appropriately selected from known static eliminators. For example, a semiconductor laser (LD), electroluminescence (EL ) Etc. are mentioned suitably.
In addition to the semiconductor laser (LD) and electroluminescence (EL), a fluorescent lamp, a tungsten lamp, a halogen lamp, a mercury lamp, a sodium lamp, a xenon lamp, or the like can be used. In order to specify the wavelength, various filters such as a sharp cut filter, a band pass filter, a near infrared cut filter, a dichroic filter, an interference filter, and a color temperature conversion filter can be used in combination with the light source.
The toner developed on the electrophotographic photosensitive member 11 by the developing device 15 is transferred to a transfer sheet. However, when toner remaining on the electrophotographic photosensitive member 11 is generated, the electrophotographic photosensitive member 11 is electrophotographic with a fur brush and a blade. It is removed from the photoreceptor. Cleaning may be performed only with a cleaning brush, and a known brush such as a fur brush or a mag fur brush is used as the cleaning brush.

  The image forming means described above may be fixedly incorporated in a copying apparatus, facsimile, or printer, but may be detachably incorporated in the image forming apparatus main body in the form of a process cartridge described below. .

<Process cartridge>
The process cartridge used in the present invention comprises an electrophotographic photosensitive member and at least one means selected from a charging means, an exposure means, a developing means, a cleaning means, and a static elimination means, and further if necessary. It has other means.
The electrophotographic photoreceptor of the present invention is used as the electrophotographic photoreceptor.

The developing means includes at least a developer container that contains the toner or the developer, and a developer carrier that carries and transports the toner or developer contained in the developer container. In addition, a layer thickness regulating member for regulating the thickness of the toner layer carried on the developer carrying member may be provided.
Further, as the charging unit, the exposure unit, the transfer unit, the cleaning unit, and the charge removal unit, the same ones as those of the above-described image forming apparatus can be appropriately selected and used.
The process cartridge can be detachably provided in various electrophotographic image forming apparatuses, facsimile machines, and printers, and it is particularly preferable that the process cartridge is detachably provided in the image forming apparatus of the present invention.

Here, for example, as shown in FIG. 6, the process cartridge includes an electrophotographic photosensitive member 101, and includes a charging unit 102, a developing unit 104, a transfer unit 108, and a cleaning unit 107. It has the means of. In FIG. 6, reference numeral 103 denotes exposure by exposure means, and 105 denotes a recording medium.
Next, an image forming process using the process cartridge shown in FIG. 6 will be described. The electrophotographic photosensitive member 101 has its surface formed by charging by the charging unit 102 and exposure 103 by the exposure unit (not shown) while rotating in the direction of the arrow. Then, an electrostatic latent image corresponding to the exposure image is formed. The electrostatic latent image is developed by the developing unit 104, and the obtained visible image is transferred to the recording medium 105 by the transfer unit 108 and printed out. Next, the surface of the electrophotographic photosensitive member after the image transfer is cleaned by the cleaning unit 107 and further neutralized by a neutralizing unit (not shown), and the above operation is repeated again.

  The image forming apparatus of the present invention can cope with a process of reducing the diameter of an electrophotographic photosensitive member and a process having a high peripheral speed, is highly sensitive and responsive in a long wavelength region, and has an initial potential even when repeatedly used at a high speed. The reproducibility of the potential after repeated use is stable, and the electrophotographic photosensitive member of the present invention that can form a high-quality image without being restricted by the use environment is used. It is suitable for digital copiers, full color copiers, full color laser printers and the like.

  Examples of the present invention will be described below, but the present invention is not limited to these examples.

(Synthesis Example 1)
-Synthesis of hydroxygallium phthalocyanine and preparation of crystal for X-ray diffraction-
30 parts by mass of 1,3-diiminoisoindoline and 9.1 parts by mass of gallium trichloride were added to 230 parts by mass of quinoline and reacted at 200 ° C. for 3 hours, and then the product was filtered off. Subsequently, it was washed with acetone and methanol, and the wet cake was dried to obtain 28 parts by mass of chlorogallium phthalocyanine crystals.
Next, 3 parts by mass of the chlorogallium phthalocyanine crystal was dissolved in 60 parts by mass of concentrated sulfuric acid at 0 ° C., and then this solution was dropped into 450 parts by mass of distilled water at 5 ° C. to precipitate a crystal. After washing with distilled water and dilute ammonia water, it was dried to obtain 2.5 parts by mass of hydroxygallium phthalocyanine crystals.
Further, 0.5 parts by mass of the hydroxygallium phthalocyanine crystal was milled for 24 hours together with 15 parts by mass of dimethylformamide and 30 parts of glass beads having a diameter of 1 mm, and then the crystals were separated.
Next, the separated crystal was washed with methanol and dried to obtain a target hydroxygallium phthalocyanine crystal.

<X-ray diffraction>
The hydroxygallium phthalocyanine crystal produced as described above was measured by a powder method, and was measured under the following conditions using CuKα (wavelength 1.542Å) as an X-ray source.
X-ray diffractometer: X'Pert manufactured by Frips
Measurement conditions: X-ray tube Cu
Tube voltage 50kV
Tube current 30mA
Scanning speed: 2 ° / min
Scanning range 3 ° ~ 40 °
Time constant: 2 seconds
Step angle 0.01 degree
Counting time 20 seconds
Receiving slit, divergent slit, variable type
Irradiation width 20mm

  An X-ray diffraction pattern of the hydroxygallium phthalocyanine crystal is shown in FIG. According to FIG. 1, the hydroxygallium phthalocyanine crystal has a Bragg angle (2θ ± 0.2 °) of 7.5 °, 9.9 °, 12.5 °, 16.3 °, 18.6 °, 25. It was found to have strong diffraction peaks at 1 ° and 28.3 °.

Example 1
-Production of electrophotographic photoreceptor-
65:35 polymerization ratio of alkyd resin (Beckolite M-6401-50, manufactured by Dainippon Ink & Chemicals, Inc.) and amino resin (Super Becamine G-821-60, manufactured by Dainippon Ink & Chemicals, Inc.) The mixed resin and titanium oxide (CR-EL Ishihara Sangyo Co., Ltd.) were mixed at a ratio of 1: 3 and dissolved in methyl ethyl ketone to prepare an undercoat layer coating solution.
Next, as a support, a cylindrical drum made of uncut aluminum having a diameter of 24 mm was dip-coated in the undercoat layer coating solution and dried at 130 ° C. for 20 minutes to form an undercoat layer having a thickness of 1.5 μm. .

  Next, 10 g of the hydroxygallium phthalocyanine powder obtained in Synthesis Example 1 is added to a solution obtained by dissolving 10 g of polyvinyl butyral resin (BM-1, manufactured by Sekisui Chemical Co., Ltd.) in 500 ml of glass beads and 1,3 dioxolane. And the resulting dispersion was filtered to remove the glass beads to prepare a charge generation layer coating solution. This was dip-coated on the undercoat layer and dried to form a charge generation layer having a thickness of 0.2 μm.

Next, polycarbonate resin (Z400, manufactured by Mitsubishi Gas Chemical Co., Inc.) as a binder resin, a compound represented by the following structural formula (Ia) as a charge transport agent, and 2.6-di-oxide as a hindered phenol-based antioxidant. -Tert-butyl-4-methylphenol and 2- (2-hydroxy-5-methylphenyl) benzotriazole (Tinvin-P, manufactured by Geigy) as a benzotriazole-based ultraviolet absorber at a mass ratio of 1.0: Prepared at 1.0: 0.05: 0.05 and dissolved in tetrahydrofuran to prepare a charge transport layer coating solution.

  Next, the support having the charge generation layer formed thereon was 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. Thus, the electrophotographic photosensitive member of Example 1 was produced.

(Example 2)
-Production of electrophotographic photoreceptor-
In Example 1, Example 2 was carried out in the same manner as in Example 1 except that the compound represented by the structural formula (Ia) as the charge transfer agent was replaced with the compound represented by the following structural formula (Ib). An electrophotographic photoreceptor was prepared.

(Example 3)
-Production of electrophotographic photoreceptor-
In Example 1, Example 3 was carried out in the same manner as Example 1, except that the compound represented by the structural formula (Ia) as the charge transfer agent was replaced with the compound represented by the following structural formula (Ic). An electrophotographic photoreceptor was prepared.

Example 4
-Production of electrophotographic photoreceptor-
In Example 1, Example 4 was performed in the same manner as in Example 1 except that the compound represented by the structural formula (Ia) as the charge transporting agent was replaced with the compound represented by the following structural formula (Id). An electrophotographic photoreceptor was prepared.

(Example 5)
-Production of electrophotographic photoreceptor-
In the same manner as in Example 1, an undercoat layer and a charge generation layer were formed on a support.
Next, a polycarbonate resin (Z400, manufactured by Mitsubishi Gas Chemical Co., Inc.) as a binder resin, a compound represented by the structural formula (Ia) as a charge transport agent, and 2.6-di-oxide as a hindered phenol-based antioxidant. -Tert-butyl-4-methylphenol, N-phenyl-1-naphthylamine as an amine-based antioxidant, distearyl-3--3-thiodipropionate (Sumilyzer TPS, Sumitomo Chemical Co., Ltd.) as a sulfur-based antioxidant Company) and 2- (5-methyl-2-hydroxyphenyl) benzotriazole (Tinuvin-P, manufactured by Geigy) as a benzotriazole-based ultraviolet absorber at a mass ratio of 1.0: 1.0: 0. Prepared at 05: 0.05: 0.01: 0.05 and dissolved in tetrahydrofuran to prepare a charge transport layer coating solution It was.
Next, the support having the charge generation layer formed thereon was 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. Thus, an electrophotographic photosensitive member of Example 5 was produced.

(Comparative Example 1)
-Production of electrophotographic photoreceptor-
Comparative Example 1 was carried out in the same manner as in Example 1 except that the compound represented by the structural formula (Ia) as the charge transfer agent in Example 1 was replaced with the compound represented by the following structural formula (A). An electrophotographic photoreceptor was prepared.
<Structural Formula (A)>

(Comparative Example 2)
-Production of electrophotographic photoreceptor-
Comparative Example 2 was carried out in the same manner as in Example 1 except that the compound represented by Structural Formula (Ia) as the charge transfer agent in Example 1 was replaced with the compound represented by the following Structural Formula (B). An electrophotographic photoreceptor was prepared.
<Structural formula (B)>

(Comparative Example 3)
-Production of electrophotographic photoreceptor-
In Example 1, the electrophotographic photosensitive member of Comparative Example 3 was obtained in the same manner as in Example 1 except that the hydroxygallium phthalocyanine shown in FIG. 1 as the charge generating agent was replaced with Y-type oxytitanium phthalocyanine shown in FIG. Was made.
The Y-type oxytitanium phthalocyanine shown in FIG. 2 exhibits a characteristic diffraction peak at a Bragg angle (2θ ± 0.2 °) of 27.2 °, and is 9.7 °, 14.2 °, 18.0 °. And also has a diffraction peak at 24.2 °.

(Comparative Example 4)
-Production of electrophotographic photoreceptor-
In Example 1, the electrophotographic photosensitive member of Comparative Example 4 was prepared in the same manner as in Example 1 except that the hydroxygallium phthalocyanine shown in FIG. 1 as the charge generating agent was replaced with β-type oxytitanium phthalocyanine shown in FIG. Was made.
The β-type oxytitanium phthalocyanine shown in FIG. 3 exhibits characteristic diffraction peaks at a Bragg angle (2θ ± 0.2 °) of 26.2 °, 10.5 °, 13.1 °, 15.1 °. And also has a diffraction peak at 20.7 °.

  Next, in Examples 1-5 and Comparative Examples 1-4, various characteristics were evaluated as follows. The results are shown in Tables 1 and 2.

<Evaluation of electrophotographic photosensitive member 1: electrostatic characteristics>
Using an electrophotographic photosensitive member evaluation apparatus (manufactured by Yamanashi Electronics Co., Ltd.), the electrophotographic photosensitive member produced in Examples 1 to 5 and Comparative Examples 1 to 4 is charged, exposed, developed, and transferred as one cycle. The initial potential was the cycle potential, and the surface potential (V0) after 10,000 cycles, the residual potential (VL), the electrostatic characteristics of the exposure amount 0.6 μJ / cm ² were measured, and the change amount was obtained for evaluation. . The results are shown in Table 1.

As is apparent from Table 1, in Examples 1 to 5, the initial charging potential, the residual potential, the charging potential after 10,000 cycles, and the residual potential are greatly changed by the combination of the charge generating agent and the charge transporting agent of the present invention. The photoconductor characteristics were good.
On the other hand, in Comparative Examples 1 and 2, the residual potential after 10,000 cycles greatly changes due to the combination of the charge generating agent of the present invention and the charge transporting agent other than the present invention, which is satisfactory as the photoreceptor characteristics. There wasn't. Further, in Comparative Examples 3 and 4, the residual potential after 10,000 cycles was greatly changed by the combination of the charge generating agent other than the present invention and the charge transporting agent of the present invention, and the photoreceptor characteristics were not satisfactory.

<Evaluation of electrophotographic photoreceptor 2: photoresponsiveness>
Using an electrophotographic photoreceptor evaluation apparatus (manufactured by Yamanashi Electronics Co., Ltd.), each electrophotographic photoreceptor produced in Examples 1 to 5 and Comparative Examples 1 to 4 is irradiated with a light amount 5 times the half exposure amount. The surface potential of the electrophotographic photosensitive member at the position of the developing device when the time from exposure to the developing device was changed was evaluated as photoresponsiveness (-V). The results are shown in Table 2. The drum peripheral speed increases as the time between the exposure and the developing device is shorter. Therefore, it is necessary to shorten this time as much as possible to improve productivity.

  As is apparent from Table 2, in Examples 1 to 5, when the time until reaching the post-exposure developer position was long, the surface potential was low regardless of whether it was short, and had excellent photoreceptor characteristics. . On the other hand, in Comparative Examples 1 to 4, when the arrival time is shortened, the surface potential is remarkably increased, which is not satisfactory as the photoreceptor characteristics.

  In addition, according to the present invention, it is possible to provide a good photoconductor that is excellent in dielectric breakdown resistance against contact charging and does not increase in residual potential.

  The electrophotographic photosensitive member of the present invention is an electrophotographic photosensitive member that can cope with the process of reducing the diameter of the electrophotographic photosensitive member and increasing the peripheral speed in accordance with the downsizing and speeding up of the copying machine and the printer device. High sensitivity and responsiveness even in the wavelength range, and the reproducibility of the initial potential and the potential after repeated use is stable even when used repeatedly at high speed, and forms high-quality images regardless of the usage environment. The residual potential is extremely low, and even when used in an erase-less electrophotographic apparatus, it has excellent electrophotographic characteristics that do not cause an afterimage and can meet high market demands. It is suitable for laser printers, digital copiers, full color copiers, full color laser printers, and the like.

1 is an X-ray diffraction pattern of hydroxygallium phthalocyanine used in Example 1. FIG. FIG. 2 is an X-ray diffraction pattern of Y-type oxytitanium phthalocyanine used in Comparative Example 3. FIG. 3 is an X-ray diffraction pattern of β-type oxytitanium phthalocyanine used in Comparative Example 4. FIG. 4 is a schematic view showing an example of the image forming apparatus of the present invention. FIG. 5 is a schematic view showing another example of the image forming apparatus of the present invention. FIG. 6 is a schematic view showing an example of a process cartridge used in the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Electrophotographic photosensitive member 12 Charging member 13 Power supply 14 Exposure device 15 Developing device 16 Transfer device 17 Cleaning device 18 Electric discharger 19 Fixing device 101 Electrophotographic photosensitive member 102 Charging means 103 Exposure by exposure means 104 Developing means 105 Recording medium 107 Cleaning means 108 Transfer means

Claims (11)

In an electrophotographic photosensitive member having a support and a photosensitive layer containing at least a charge generator, a charge transport agent, and a binder resin on the support,
The charge generating agent in the photosensitive layer is hydroxygallium phthalocyanine;
The electrophotographic photoreceptor, wherein the charge transport agent contains a compound represented by the following general formula (I).
However, the general formula (I), R ¹ ~R ² has each independently a hydrogen atom, a halogen atom, an optionally substituted alkyl group having 1 to 6 carbon atoms, and the substituents Any one of the C1-C6 alkoxy groups which may be present. The electrophotographic photoreceptor according to claim 1, wherein the charge transport agent contains a compound represented by the following structural formula (Ia).
The electrophotographic photosensitive member according to claim 1, wherein the charge transfer agent contains a compound represented by the following structural formula (Ib).
The electrophotographic photosensitive member according to claim 1, wherein the charge transport agent contains a compound represented by the following structural formula (Ic).
The electrophotographic photoreceptor according to claim 1, wherein the charge transport agent contains a compound represented by the following structural formula (Id).
  Hydroxygallium phthalocyanine has a Bragg angle (2θ ± 0.2 °) of 7.5 °, 9.9 °, 12.5 °, 16.3 °, 18.6 in an X-ray diffraction spectrum using CuKα as a radiation source. The electrophotographic photosensitive member according to claim 1, which has diffraction peaks at °, 25.1 °, and 28.3 °.   The electrophotographic photosensitive member according to claim 1, wherein the photosensitive layer contains a hindered phenol-based antioxidant.   The electrophotographic photosensitive member according to claim 1, wherein the photosensitive layer contains an amine-based antioxidant.   The electrophotographic photosensitive member according to claim 1, wherein the photosensitive layer contains a sulfur-based antioxidant.   The electrophotographic photosensitive member according to claim 1, wherein the photosensitive layer contains a benzotriazole-based ultraviolet absorber. An electrophotographic photosensitive member; a charging unit that charges the surface of the electrophotographic photosensitive member; an exposing unit that exposes the surface of the charged electrophotographic photosensitive member to form an electrostatic latent image; and An image forming apparatus having at least developing means for developing a visible image by using the developing means and transfer means for transferring the visible image to a recording medium,
An image forming apparatus, wherein the electrophotographic photosensitive member is the electrophotographic photosensitive member according to claim 1.