JP5719886B2 - Electrophotographic photosensitive member and image forming apparatus using the same - Google Patents

Description

  The present invention relates to an electrophotographic photosensitive member and an image forming apparatus using the same. More specifically, the present invention relates to an electrophotographic photosensitive member in which the surface layer of the photosensitive member contains oxygen-containing fluorine-based fine particles and an image forming apparatus using the same.

  An electrophotographic image forming apparatus (hereinafter also referred to as an electrophotographic apparatus) used as a copying machine, a printer, a facsimile machine, or the like forms an image through the following electrophotographic process.

First, a photosensitive layer of an electrophotographic photoreceptor (hereinafter also simply referred to as a photoreceptor) provided in the apparatus is uniformly charged to a predetermined potential by a charger.
Next, exposure is performed by light such as laser light emitted from the exposure unit in accordance with image information to form an electrostatic latent image.
The developer is supplied from the developing means to the formed electrostatic latent image, and the electrostatic latent image is developed by attaching colored fine particles called toner, which is a component of the developer, to the surface of the photoreceptor. It is visualized as a toner image.
The formed toner image is transferred from the surface of the photoreceptor to a transfer material such as recording paper by a transfer unit, and fixed by a fixing unit.

  However, not all the toner on the surface of the photoconductor is transferred to the recording paper and transferred during the transfer operation by the transfer means, but a part of the toner remains on the surface of the photoconductor. Further, the paper dust of the recording paper that comes into contact with the photoconductor during transfer may remain attached to the surface of the photoconductor. Such foreign matters such as residual toner and adhering paper dust on the surface of the photosensitive member adversely affect the quality of the formed image and are removed by the cleaning device.

In recent years, cleaner-less technology has progressed, and there is also a method of removing the foreign matter by a so-called developing and cleaning system that collects residual toner by a cleaning function added to the developing unit without having an independent cleaning unit.
In this method, after the surface of the photosensitive member is cleaned, the surface of the photosensitive layer is neutralized by a static eliminator or the like so that the electrostatic latent image disappears.
An electrophotographic photoreceptor used in such an electrophotographic process is configured by laminating a photosensitive layer containing a photoconductive material on a conductive substrate made of a conductive material.

  Examples of the electrophotographic photoreceptor include a photoreceptor using an inorganic photoconductive material or an organic photoconductive material (hereinafter referred to as an organic photoconductor; abbreviated name: OPC). Research and development have improved the sensitivity and durability of organic photoreceptors, and organic photoreceptors are now widely used.

In recent years, the electrophotographic photosensitive member has been mainly composed of a multilayer photosensitive member in which a photosensitive layer is functionally separated into a charge generating layer containing a charge generating material and a charge transporting layer containing a charge transporting material. ing. In many cases, a charge transport layer in which a charge transport material having charge transport capability is dispersed in a molecular form in a binder resin is laminated on a charge generation layer in which a charge generation material is deposited or dispersed in a binder resin. It is a negatively charged photoreceptor. In addition, a single layer type photoreceptor in which a charge generation material and a charge transport material are uniformly dispersed and dissolved in the same binder resin has been proposed.
Further, in order to improve the print image quality, an undercoat layer is provided between the conductive substrate and the photosensitive layer.

  As a disadvantage of the organic photoreceptor, there is a surface wear caused by slid printing such as a cleaner around the photoreceptor due to the nature of the organic material. As a means for overcoming this drawback, it has been attempted to improve the mechanical properties of the material of the photoreceptor surface.

  As an effort, a protective layer is provided on the outermost surface layer of the photoconductor to impart lubricity (for example, JP-A-1-23259: Patent Document 1), and filler particles are contained in the protective layer (for example, JP-A-1-1). No. 172970: Patent Document 2) is known. Among them, studies have been made to add fluorine-based particles to the surface as a filler (for example, Patent 3416310: Patent Document 3). As a feature of fluorine-based particles, from the high lubrication function derived from the material, as a filler, it not only improves the mechanical properties of the photoconductor, but also provides lubricity, thereby friction with the member in contact with the photoconductor process Reducing the force also contributes to improving the printing durability of the photoreceptor surface.

  Fluorine-based fine particles, for example, polytetrafluoroethylene (PTFE) particles have an excellent lubricating function as a material, but the PTFE molecules forming the fine particles have no polarity, so the cohesive force of the fine particles becomes very large. , There is a drawback that the dispersibility is extremely poor when the dispersion liquid of the particles is prepared. Therefore, when dispersing PTFE fine particles for use in a photoreceptor, it is necessary to use a dispersant (for example, Japanese Patent No. 3186010: Patent Document 4), and as a result, the electrical characteristics of the photoreceptor are deteriorated.

JP-A-1-23259 JP-A-1-172970 Japanese Patent No. 3416310 Japanese Patent No. 3186010

As described above, when the fluorine-based fine particles are added to the surface layer of the photoreceptor, it is inevitable to use a dispersant, and the electrical characteristics of the photoreceptor deteriorate due to the addition of the dispersant. In addition, even with the addition of a dispersant, sufficient dispersion stability cannot be ensured at present.
Therefore, in the present invention, by adding oxygen-containing fluorine-based fine particles to the surface of the photoreceptor, not only excellent wear resistance and photoreceptor characteristics can be stably secured, but also dispersion stability as a photoreceptor coating liquid can be achieved. By improving, it is to ensure the production stability of the electrophotographic photosensitive member in which the oxygen-containing fluorine-based fine particles in the surface layer of the photosensitive member are uniformly dispersed.

  As a result of intensive studies to solve the above problems, the present inventors obtained an electrophotographic photosensitive member having a photosensitive layer formed on a conductive substrate by a specific technique on the outermost surface layer of the photosensitive member. It has been found that by containing oxygen-containing fluorine-based fine particles at a certain ratio, it is possible to provide a photoconductor that is excellent in dispersion stability as a photoconductor coating solution, has excellent wear resistance, and is electrically stable. It came to complete.

  Thus, according to the present invention, in an electrophotographic photosensitive member having a photosensitive layer formed on a conductive substrate, the surface layer contains oxygen-containing fluorine-based fine particles, and the oxygen-containing composition ratio in the fine particles. However, it is 0.9 to 3.0 atomic% of the whole fine particles in the composition analysis by fluorescent X-rays.

According to the present invention, the oxygen-containing fluorine-based fine particles are
Polytetrafluoroethylene fine particles are irradiated with γ-rays from cobalt 60 in the atmosphere, or
Using tetrafluoroethylene monomer as a raw material, the following steps:
(A) a step of polymerizing the tetrafluoroethylene monomer by irradiating a mixed solution of the tetrafluoroethylene monomer and acetone with ionizing radiation to make the mixed solution into an acetone dispersion of polytetrafluoroethylene in a gel state;
(B) cross-linking the polytetrafluoroethylene by irradiating the acetone dispersion of polytetrafluoroethylene with ionizing radiation to form a fine particle suspension; and optional (c) from the fine particle suspension. Isolating oxygen-containing fluorine-based fine particles by separation and drying;
The electrophotographic photosensitive member according to claim 1, which is obtained by the above.

  According to the present invention, the oxygen-containing fluorine-based fine particles contain oxygen having a composition ratio of 1.0 to 3.0 atomic%, and the oxygen-containing fluorine-based fine particles are primary particles of 0.1 to 2 μm. The electrophotographic photosensitive member having a median diameter (D50) of 5 mm is provided.

  In addition, according to the present invention, there is provided the electrophotographic photoreceptor, wherein the photoreceptor surface layer contains 1.0 to 40 wt% of oxygen-containing fluorine-based fine particles.

  Further, the electrophotographic photosensitive member, a charging unit for charging the electrophotographic photosensitive member, an exposure unit for exposing the charged electrophotographic photosensitive member to form an electrostatic latent image, and the electrostatic latent image An image forming apparatus comprising: a developing unit that develops a toner image by developing toner; a transfer unit that transfers the toner image onto a recording material; and a fixing unit that fixes the transferred toner image onto the recording material. Is provided.

  According to the present invention, by containing fluorine-based fine particles polymerized by a specific preparation method in the uppermost layer of the electrophotographic photoreceptor, the dispersion stability as the photoreceptor coating liquid is high and the wear resistance is high. It has become possible to provide an electrophotographic photoreceptor that is electrically stable over a long period of time and an image forming apparatus including the photoreceptor.

1 is a schematic diagram (cross-sectional view) showing a configuration of an electrophotographic photosensitive member according to Embodiment 1 of the present invention. It is a schematic diagram (sectional view) showing the configuration of the electrophotographic photosensitive member according to the second embodiment of the present invention. It is a schematic diagram (cross-sectional view) showing the configuration of the electrophotographic photoreceptor according to the third exemplary embodiment of the present invention. It is a schematic diagram (side view) which shows the structure of the image forming apparatus which concerns on Embodiment 4 of this invention.

  The electrophotographic photoreceptor of the present invention is characterized in that the uppermost layer of the photosensitive layer provided on the conductive substrate contains a specific amount of oxygen-containing fluorine-based fine particles.

  The photoreceptor according to the present invention can be applied to either a single layer type or a laminated type. Moreover, you may have a charge transport layer as an outermost surface layer, and you may provide a protective layer as an outermost layer separately. Moreover, it is possible to further stabilize electrically by using an undercoat layer.

  In the embodiment of the present invention, the fluorine-based fine particles used have a specific oxygen composition ratio. That is, the composition ratio of oxygen contained in the fine particles is 0.9 to 3.0 atomic% (hereinafter also simply expressed as%) of the whole fine particles in the composition analysis by fluorescent X-rays, and more preferably 1.0 to 1.0. 3.0 atomic%.

  In order to keep the contained oxygen composition ratio within a desired range, structural modification of fluorine-based fine particles by radiation is essential. That is, as the radiation, γ-ray irradiation is preferable, and a desired oxygen composition ratio can be obtained by irradiating the fluorine-based fine particles while changing the dose of γ-ray.

Although details are not clear, as described in the following examples, oxygen is contained by taking in oxygen in the air, carbon dioxide, or oxygen derived from the solvent used, which is present in the vicinity of the PTFE fine particles irradiated with γ rays. Fluorine-based fine particles (also referred to as oxygen-containing crosslinked polytetrafluoroethylene (PTFE)) are considered to be formed.
In addition, similar oxygen introduction is possible by electron beam irradiation.

More preferably, the oxygen-containing fluorine-based fine particles in the present invention are those in which the oxygen-containing fluorine-based fine particles are those obtained by irradiating polytetrafluoroethylene fine particles with γ rays from cobalt 60 in the atmosphere, or tetrafluoroethylene monomer. The following process:
(A) a step of polymerizing the tetrafluoroethylene monomer by irradiating a mixed solution of the tetrafluoroethylene monomer and acetone with ionizing radiation to make the mixed solution into an acetone dispersion of polytetrafluoroethylene in a gel state;
(B) cross-linking the polytetrafluoroethylene by irradiating the acetone dispersion of polytetrafluoroethylene with ionizing radiation to form a fine particle suspension; and optional (c) from the fine particle suspension. Isolating oxygen-containing fluorine-based fine particles by separation and drying;
It may be derived from the fine particle suspension obtained by the above, or may be the separated oxygen-containing fluorine-based fine particles.

  The image forming apparatus of the present invention includes the electrophotographic photosensitive member, a charging unit that charges the electrophotographic photosensitive member, and an exposure unit that exposes the charged electrophotographic photosensitive member to form an electrostatic latent image. Developing means for developing the electrostatic latent image with toner to form a toner image; transfer means for transferring the toner image onto the recording material; and fixing the transferred toner image onto the recording material. The image forming apparatus further includes a fixing unit, and further includes a cleaning unit that removes and collects toner remaining on the electrophotographic photosensitive member, and a neutralizing unit that neutralizes surface charges remaining on the electrophotographic photosensitive member. Also good. The image forming apparatus of the present invention may be configured to include the electrophotographic photosensitive member, a charging unit, an exposure unit, a developing unit, and a transfer unit.

  Hereinafter, embodiments and examples of the present invention will be specifically described with reference to FIGS. Note that the embodiments and examples described below are merely specific examples of the present invention, and the present invention is not limited thereto.

Embodiment 1
FIG. 1 is a schematic diagram (cross-sectional view) showing a configuration of the electrophotographic photosensitive member according to the first exemplary embodiment of the present invention.
The electrophotographic photoreceptor 1 (hereinafter abbreviated as “photoreceptor”) according to Embodiment 1 contains an undercoat layer 15 and a charge generation material on a cylindrical conductive substrate 11 made of a conductive material. The photoconductive layer 14 is composed of a photosensitive layer 14 in which a charge generation layer 12 and a charge transport layer 13 containing a charge transport material are laminated in this order.

Conductive substrate (hereinafter also referred to as conductive support)
The conductive substrate 11 serves as an electrode of the photoreceptor 1 and also functions as a support member for the layers disposed thereon, that is, the undercoat layer 15 and the photosensitive layer 14.
In addition, although the shape of the electroconductive base | substrate 11 is cylindrical shape in this Embodiment 1, it is not limited to this, A column shape, a sheet form, or an endless belt shape etc. may be sufficient.

  Examples of the conductive material constituting the conductive substrate 11 include conductive metals such as aluminum, copper, brass, zinc, nickel, stainless steel, chromium, molybdenum, vanadium, indium, titanium, gold, and platinum; or aluminum alloys And metal oxides such as tin oxide and indium oxide can be used.

Also, without being limited to these metal materials, a polymer material such as polyethylene terephthalate, nylon, polyester, polyoxymethylene or polystyrene, a laminate of the metal foil on the surface of hard paper or glass; A vapor-deposited material or a material obtained by vapor-depositing or coating a conductive compound layer such as a conductive polymer, tin oxide, or indium oxide can also be used.
These conductive materials are used after being processed into a predetermined shape.

If necessary, the surface of the conductive substrate 11 is irregularly reflected within a range that does not affect the image quality, such as anodic oxide film treatment, surface treatment with chemicals or hot water, coloring treatment, or roughening the surface. Processing may be performed.
In an electrophotographic process using a laser as an exposure light source, the wavelengths of the laser light are uniform, so the laser light reflected on the surface of the photoconductor and the laser light reflected inside the photoconductor cause interference, and the interference due to this interference occurs. Stripes may appear on the image and cause image defects.
However, by performing the above-described treatment on the surface of the conductive substrate 11, image defects due to interference of laser light having the same wavelength can be prevented.

Undercoat layer (hereinafter also referred to as intermediate layer)
When the undercoat layer 15 is not provided between the conductive substrate 11 and the photosensitive layer 14, the chargeability is reduced in a minute region due to defects in the conductive substrate 11 or the photosensitive layer 14, and black spots or the like are caused. Image fogging may occur, resulting in significant image defects. By providing the undercoat layer, injection of charges from the conductive substrate 11 to the photosensitive layer 14 can be prevented.
Therefore, the provision of the undercoat layer 15 can prevent the chargeability of the photosensitive layer 14 from being lowered, suppress the reduction of the surface charge other than the portion to be erased by exposure, and cause defects such as fogging on the image. Can be prevented.

Further, by providing the undercoat layer 15, it is possible to cover the unevenness of the surface of the conductive substrate 11 to obtain a uniform surface, so that the film formability of the photosensitive layer 14 is improved and the conductive substrate 11 of the photosensitive layer 14 is improved. Can be prevented from being peeled off, and the adhesion between the conductive substrate 11 and the photosensitive layer 14 can be improved.
For the undercoat layer 15, a resin layer or an alumite layer made of various resin materials is used.

  The resin material constituting the resin layer as the undercoat layer 15 includes polyethylene resin, polypropylene resin, polystyrene resin, acrylic resin, vinyl chloride resin, vinyl acetate resin, polyurethane resin, epoxy resin, polyester resin, melamine resin, and silicone resin. And resins such as polyvinyl butyral resin, polyvinyl pyrrolidone resin, polyacrylamide resin and polyamide resin, and copolymer resins containing two or more repeating units constituting these resins. Further, casein, gelatin, polyvinyl alcohol, cellulose, nitrocellulose, ethylcellulose and the like are also included.

Among these resins, it is preferable to use a polyamide resin, and it is particularly preferable to use an alcohol-soluble nylon resin.
Preferred alcohol-soluble nylon resins include so-called nylons such as 6-nylon, 6,6-nylon, 6,10-nylon, 11-nylon, 2-nylon and 12-nylon, and N-alkoxymethyl-modified nylon and Examples thereof include resins obtained by chemically modifying nylon such as N-alkoxyethyl-modified nylon.

  In order to give the undercoat layer a charge adjusting function, a filler which is metal oxide fine particles is added. Examples of such a filler include particles of titanium oxide, aluminum oxide, aluminum hydroxide, tin oxide and the like. The particle diameter of the metal oxide is suitably about 0.01 to 0.3 μm, preferably about 0.02 to 0.1 μm.

The undercoat layer 15 is formed by, for example, preparing an intermediate layer coating solution by dissolving or dispersing the above-described resin in a suitable solvent and coating the coating solution on the surface of the conductive substrate 11. .
When the undercoat layer 15 contains particles such as the metal oxide fine particles, the metal oxide fine particles such as titanium oxide are dispersed in a resin solution obtained by dissolving the resin in an appropriate solvent. The undercoat layer 15 can be formed by preparing an undercoat layer coating solution and applying the coating solution to the surface of the conductive substrate 11.

As the solvent for the coating solution for the undercoat layer, water, various organic solvents, or a mixed solvent thereof is used. For example, water or alcohol such as methanol, ethanol or butanol alone, or water and alcohol, a mixture of two or more alcohols, acetone or dioxolane and alcohol, halogen organic solvents such as dichloroethane, chloroform or trichloroethane and alcohol, etc. A mixed solvent is used.
Among these solvents, non-halogen organic solvents are preferably used in consideration of the global environment.

As a method for dispersing the particles in the resin solution, a general dispersion method using a ball mill, a sand mill, an attritor, a vibration mill, an ultrasonic disperser, a paint shaker, or the like can be used.
In addition, a more stable dispersion coating liquid can be produced by using a medialess type dispersion apparatus that uses a very strong shearing force generated by passing the dispersion liquid through a micro gap at an ultrahigh pressure. It becomes possible.

Examples of the coating method for the coating solution for the undercoat layer include a spray method, a bar coating method, a roll coating method, a blade method, a ring method, and a dip coating method.
Among these coating methods, in particular, the dip coating method is a method of forming a layer on the surface of the substrate by immersing the substrate in a coating tank filled with a coating solution and then pulling it up at a constant speed or a speed that changes sequentially. Since it is relatively simple and excellent in terms of productivity and cost, it is widely used in the production of electrophotographic photosensitive members. In addition, in order to stabilize the dispersibility of a coating liquid, the apparatus used for the dip coating method may be provided with a coating liquid dispersing apparatus represented by an ultrasonic generator.

The thickness of the undercoat layer 15 is preferably 0.01 μm to 20 μm, more preferably 0.05 μm to 10 μm.
If the thickness of the undercoat layer 15 is less than 0.01 μm, the unevenness of the conductive substrate 11 cannot be covered and uniform surface properties cannot be obtained. This is not preferable because the injection of charges from the photosensitive substrate 11 to the photosensitive layer 14 cannot be prevented and the chargeability of the photosensitive layer 14 is lowered.

On the other hand, if the thickness of the undercoat layer 15 is greater than 20 μm, it is difficult to form the undercoat layer 15 by the dip coating method, and the photosensitive layer 14 cannot be uniformly formed on the undercoat layer 15. This is not preferable because the sensitivity of is reduced.
Therefore, a preferable range of the thickness of the undercoat layer 15 is 0.01 to 20 μm.

Charge Generation Layer The charge generation layer 12 contains, as a main component, a charge generation substance that generates charges by absorbing light.
Examples of the charge generating substance include an organic photoconductive material containing an organic pigment and an inorganic photoconductive material containing an inorganic pigment.

  Examples of the organic photoconductive materials include azo pigments such as monoazo pigments, bisazo pigments and trisazo pigments, indigo pigments such as indigo and thioindigo, perylene pigments such as peryleneimide and perylene anhydride, anthraquinone and Examples include organic photoconductive materials such as polycyclic quinone pigments such as pyrenequinone, phthalocyanine pigments such as metal phthalocyanine and metal-free phthalocyanine, squarylium dyes, pyrylium salts and thiopyrylium salts, and triphenylmethane dyes.

  Examples of the inorganic photoconductive material include selenium and its alloys, arsenic-selenium, cadmium sulfide, zinc oxide, amorphous silicon, and other inorganic photoconductors.

  Charge generation materials include triphenylmethane dyes represented by methyl violet, crystal violet, knight blue and Victoria blue, erythrosine, rhodamine B, rhodamine 3R, acridine dyes represented by acridine orange and frapeosin, methylene blue and methylene It may be used in combination with sensitizing dyes such as thiazine dyes typified by green, oxazine dyes typified by capri blue and meldra blue, cyanine dyes, styryl dyes, pyrylium salt dyes or thiopyrylium salt dyes. .

As a method of forming the charge generation layer 12, the charge generation material is vacuum-deposited on the surface of the conductive substrate 11, or the charge generation layer is obtained by dispersing the charge generation material in a suitable solvent. A method of applying the liquid to the surface of the conductive substrate 11 is used.
Among these, in a binder resin solution obtained by mixing a binder resin as a binder in a solvent, a charge generating material is dispersed by a conventionally known method to prepare a coating solution for a charge generating layer, A method of applying the obtained coating solution to the surface of the conductive substrate 11 is preferably used. Hereinafter, this method will be described.

  Examples of the binder resin used for the charge generation layer 12 include polyester resin, polystyrene resin, polyurethane resin, phenol resin, alkyd resin, melamine resin, epoxy resin, silicone resin, acrylic resin, methacrylic resin, polycarbonate resin, and polyarylate resin. And resins such as phenoxy resin, polyvinyl butyral resin, polyvinyl chloride resin and polyvinyl formal resin, and copolymer resins containing two or more of the repeating units constituting these resins.

Specific examples of the copolymer resin include insulating resins such as vinyl chloride-vinyl acetate copolymer resin, vinyl chloride-vinyl acetate-maleic anhydride copolymer resin, and acrylonitrile-styrene copolymer resin. be able to.
The binder resin is not limited to these, and a commonly used resin can be used as the binder resin. One kind of these resins may be used alone, or two or more kinds thereof may be mixed and used.

  Examples of the solvent of the coating solution for the charge generation layer include halogenated hydrocarbons such as dichloromethane or dichloroethane, alcohols such as methanol and ethanol, ketones such as acetone, methyl ethyl ketone and cyclohexanone, esters such as ethyl acetate and butyl acetate, Ethers such as tetrahydrofuran or dioxane, alkyl ethers of ethylene glycol such as 1,2-dimethoxyethane, aromatic hydrocarbons such as benzene, toluene or xylene, or N, N-dimethylformamide or N, N-dimethylacetamide An aprotic polar solvent such as is used.

  Among the above solvents, non-halogen organic solvents are preferably used in consideration of the global environment. As for said solvent, 1 type may be used independently and may be used as 2 or more types of mixed solvents.

In the charge generation layer 12 including the charge generation material and the binder resin, the ratio W1 / W2 between the weight W1 of the charge generation material and the weight W2 of the binder resin is 10/100 (10/100). It is preferable that it is 400/100 (400/100).
When the ratio W1 / W2 is less than 10/100, the sensitivity of the photoreceptor 1 is likely to be lowered.
On the other hand, when the ratio W1 / W2 exceeds 400/100, not only the film strength of the charge generation layer 12 decreases, but also the dispersibility of the charge generation material decreases and coarse particles increase. The surface charge other than the portion to be reduced is reduced, and the image defects, particularly the fogging of the image called black spots where the toner adheres to the white background and minute black spots are formed increases.
Therefore, a suitable range of the ratio W1 / W2 is 10/100 to 400/100.

The charge generation material may be pulverized in advance by a pulverizer before being dispersed in the binder resin solution.
Examples of the pulverizer used for the pulverization treatment include a ball mill, a sand mill, an attritor, a vibration mill, and an ultrasonic disperser.
In addition, examples of the disperser used when the charge generating substance is dispersed in the binder resin solution include a paint shaker, a ball mill, and a sand mill. As a dispersion condition at this time, an appropriate condition is selected so that impurities are not mixed due to wear of a container and a member constituting the disperser.

Examples of the coating method for the charge generation layer coating liquid include a spray method, a bar coating method, a roll coating method, a blade method, a ring method, and a dip coating method.
Among these application methods, an optimum method can be selected in consideration of the physical properties and productivity of the application.
Among these coating methods, the dip coating method described in the undercoat layer coating method is particularly preferable.

The film thickness of the charge generation layer 12 is preferably 0.05 μm to 5 μm, more preferably 0.1 μm to 1 μm.
When the thickness of the charge generation layer 12 is less than 0.05 μm, the charge generation efficiency due to light absorption decreases, and the sensitivity of the photoreceptor 1 decreases.
On the contrary, if the film thickness of the charge generation layer 12 exceeds 5 μm, the light absorption efficiency is lowered, and charge transfer within the charge generation layer 12 becomes a rate-limiting step in the process of erasing the surface charge of the photosensitive layer 14. As a result, the sensitivity of the photoreceptor 1 is lowered.
Therefore, a preferable range of the film thickness of the charge generation layer 12 is 0.05 μm to 5 μm.

Charge Transport Layer A charge transport layer 13 is provided on the charge generation layer 12. The charge transport layer 13 is configured to include a charge transport material that receives and transports a charge generated by the charge generation material contained in the charge generation layer 12, and a binder resin that binds the charge transport material.

The above charge transport materials include enamine derivatives, carbazole derivatives, oxazole derivatives, oxadiazole derivatives, thiazole derivatives, thiadiazole derivatives, triazole derivatives, imidazole derivatives, imidazolone derivatives, imidazolidine derivatives, bisimidazolidine derivatives, styryl compounds, hydrazones. Compound, polycyclic aromatic compound, indole derivative, pyrazoline derivative, oxazolone derivative, benzimidazole derivative, quinazoline derivative, benzofuran derivative, acridine derivative, phenazine derivative, aminostilbene derivative, triarylamine derivative, triarylmethane derivative, phenylenediamine derivative And stilbene derivatives and benzidine derivatives.
As the binder resin constituting the charge transport layer 13, a resin mainly composed of polycarbonate, which is well known in the art, is suitably selected for the reason of excellent transparency and printing durability.

  In addition, as the second component, for example, a vinyl polymer resin such as polymethyl methacrylate resin, polystyrene resin, and polyvinyl chloride resin, and a copolymer resin containing two or more of repeating units constituting these, and a polyester resin Polyester carbonate resin, polysulfone resin, phenoxy resin, epoxy resin, silicone resin, polyarylate resin, polyamide resin, polyether resin, polyurethane resin, polyacrylamide resin, and phenol resin. Moreover, the thermosetting resin which partially bridge | crosslinked these resin is also mentioned. These resins may be used alone, or a mixture of two or more kinds may be used.

  In addition, said main component means that weight% of polycarbonate resin occupies the highest ratio in the total binder resin which comprises a charge transport layer, More preferably, it is the range of 50 to 90 weight%. Means that.

The resin as the second component can be used in the range of 10 to 50% by weight in the total binder resin.
The ratio of the charge transport material and the binder resin in the charge transport layer is preferably in the range of 10/10 to 10/18 by weight ratio.

When the charge transport layer 13 is the outermost layer of the photoreceptor, filler particles can be added for the purpose of improving the wear resistance of the transport layer.
The filler particles are roughly classified into organic filler particles and inorganic filler particles centered on metal oxides.
From the viewpoint of mechanical properties for improving the wear resistance of the charge transport layer 13, it is often advantageous to use a metal oxide having a relatively high hardness as the filler particles.

However, when filler particles are added to the charge transport layer 13, the following requirements are required for the filler particles, such as not impairing the electrical characteristics of the charge transport layer 13.
That is, when filler particles having a relative dielectric constant in the charge transport layer 13 that is significantly larger than the average relative dielectric constant (εr) of the organic photoreceptor (εr> 10) (for example, εr> 10) are used, It is considered that the dielectric constant becomes non-uniform and the electrical characteristics are adversely affected.
Therefore, it is considered that filler particles having a relatively low relative dielectric constant can be suitably used for the charge transport layer without causing a great adverse effect on the electrical characteristics of the charge transport layer.
Accordingly, as filler particles added to the charge transport layer 13, organic filler particles are generally more advantageous than metal oxides having a high relative dielectric constant.
In addition, when the purpose is to impart lubricity to the outermost layer of the photoreceptor, selection of a material such as fluorine fine particles is advantageous.

  Further, in order to minimize the adverse effects on light scattering and electrical carriers in the charge transport layer 13, it is preferable to use a filler having a small particle diameter. Specifically, filler particles having a median diameter (D50) of primary particles of 0.1 to 2 μm are preferable from the viewpoint of dispersion stability of a coating liquid containing the filler particles.

The addition amount of the filler particles is 1 to 40 wt%, preferably 1.5 to 35 wt%, based on the total weight of the charge transport material and the binder resin (solid content of the charge transport layer).
When the added amount of the filler particles is less than 1 wt%, the function as a filler is not achieved and the printing durability is not improved.
On the other hand, if it exceeds 40 wt%, the electrical characteristics as a photoconductor deteriorate due to the addition of insulating filler fine particles, a sufficient image density cannot be obtained, image quality defects occur, and there is a problem in practical use. It becomes.

As a method for dispersing the filler particles, a general method using a ball mill, a sand mill, an attritor, a vibration mill, an ultrasonic disperser, a paint shaker, or the like can be used similarly to the oxide fine particles added to the undercoat layer. .
It is also possible to produce a more stable dispersion coating liquid by using a medialess type dispersion apparatus that uses a very strong shearing force generated by passing the dispersion liquid through a micro gap at an ultrahigh pressure. it can.

  Various additives may be added to the charge transport layer 13 as necessary. That is, a plasticizer or a leveling agent may be added to the charge transport layer 13 in order to improve the film formability, flexibility, or surface smoothness.

Examples of the plasticizer include dibasic acid esters such as phthalate esters, fatty acid esters, phosphate esters, chlorinated paraffins, and epoxy type plasticizers.
Moreover, as said leveling agent, a silicone type leveling agent etc. can be mentioned, for example.

  As in the case of forming the charge generation layer 12 by coating, the charge transport layer 13 includes, for example, a charge transport material, a binder resin, the filler particles, and, if necessary, the additive in a suitable solvent. The charge transport layer coating solution is prepared by dissolving or dispersing, and the resulting coating solution is applied onto the charge generation layer 12.

Examples of the solvent for the charge transport layer coating solution include aromatic hydrocarbons such as benzene, toluene, xylene and monochlorobenzene, halogenated hydrocarbons such as dichloromethane and dichloroethane, ethers such as tetrahydrofuran, dioxane and dimethoxymethyl ether, and Examples include aprotic polar solvents such as N, N-dimethylformamide. These solvents may be used alone or in combination of two or more.
Further, if necessary, a solvent such as alcohols, acetonitrile or methyl ethyl ketone can be further added to the above solvent.
Among these solvents, non-halogen organic solvents are preferably used in consideration of the global environment.

  Examples of the coating method for the charge transport layer coating solution include a spray method, a bar coating method, a roll coating method, a blade method, a ring method, and a dip coating method. Among these coating methods, the dip coating method is particularly excellent in various respects as described above, and can be used when the charge transport layer 13 is formed.

The thickness of the charge transport layer 13 is preferably 5 μm to 40 μm, and more preferably 10 μm to 30 μm.
If the film thickness of the charge transport layer 13 is less than 5 μm, the charge retention ability is lowered and it becomes difficult to obtain a clear image, which is not preferable.
On the other hand, if the thickness of the charge transport layer 13 exceeds 40 μm, the resolution of the photoreceptor 1 is lowered.
Therefore, a preferable range of the thickness of the charge transport layer 13 is 5 μm to 40 μm.

  Each layer of the photosensitive layer 14 is added with one or more sensitizers such as an electron accepting substance and a dye in order to improve sensitivity and further suppress an increase in residual potential and fatigue due to repeated use. Also good.

  Examples of the electron acceptor include acid anhydrides such as succinic anhydride, maleic anhydride, phthalic anhydride, 4-chloronaphthalic anhydride, cyano compounds such as tetracyanoethylene and terephthalmalondinitrile, 4-nitrobenzaldehyde, and the like. Aldehydes, anthraquinones such as anthraquinone and 1-nitroanthraquinone, polycyclic or heterocyclic nitro compounds such as 2,4,7-trinitrofluorenone, 2,4,5,7-tetranitrofluorenone, and diphenoquinone compounds The electron-withdrawing material can be used. Moreover, what polymerized these electron-withdrawing materials can also be used.

  As the dye, for example, an organic photoconductive compound such as xanthene dye, thiazine dye, triphenylmethane dye, quinoline pigment or copper phthalocyanine can be used. These organic photoconductive compounds function as optical sensitizers.

  Further, an antioxidant or an ultraviolet absorber may be added to each of the layers 12 and 13 of the photosensitive layer 14. In particular, it is preferable to add an antioxidant or an ultraviolet absorber to the charge transport layer 13, and the stability of the coating liquid when each layer is formed by coating can be enhanced. Furthermore, it is particularly preferable to add an antioxidant to the charge transport layer 13. By adding this antioxidant to the charge transport layer, deterioration of the photosensitive layer with respect to an oxidizing gas such as ozone or nitrogen oxide can be reduced.

Examples of the antioxidant include phenol compounds, hydroquinone compounds, tocopherol compounds, and amine compounds. Among these, a hindered phenol derivative or a hindered amine derivative, or a mixture thereof is preferably used.
Moreover, a surface protective layer may be provided as needed.

Embodiment 2
In the first embodiment described above, the configuration of the laminated photosensitive layer in which the photosensitive layer 14 includes the charge generation layer 12 and the charge transport layer 13 has been described. However, as shown in FIG. Or a single-layer type photosensitive layer.
That is, the photoreceptor 1 is a cylindrical conductive substrate 11 made of a conductive material, and a layer laminated on the outer peripheral surface of the conductive substrate 11, and a photosensitive layer 14 containing a charge generating substance and a charge transporting substance. May be formed.

Embodiment 3
As shown in FIG. 3, the charge transport layer 13 may be formed of a plurality of layers.
That is, the charge transport layer is formed by laminating two different charge transport layers 13A and 13B, and oxygen-containing fluorine-based fine particles are added to the outermost charge transport layer 13B. That is, in FIG. 3, the charge transport layer 13 is composed of the first charge transport layer 13A and the second charge transport layer 13B, and the content of the charge transport material in the first charge transport layer 13A and the second charge transport layer 13B. The second charge transport layer 13 </ b> B is formed so as to have a different content from that of the filler particles.
Thus, when a plurality of layers are laminated to form the charge transport layer 13, filler particles may be contained in the layer on the surface side of the charge transport layer 13.

Embodiment 4
FIG. 4 is a schematic diagram (cross-sectional view) showing the configuration of the image forming apparatus according to the present invention.
An image forming apparatus 30 shown in FIG. 4 is a laser printer equipped with the photoreceptor 1 according to the first embodiment of the present invention.
Hereinafter, the configuration of the laser printer 30 and the image forming operation will be described with reference to FIG.
The laser printer 30 illustrated in FIG. 4 is an exemplification of the present invention, and the image forming apparatus of the present invention is not limited by the following description.

A laser printer 30 as an image forming apparatus includes a photosensitive member 1, a semiconductor laser 31, a rotary polygon mirror 32, an imaging lens 34, a mirror 35, a corona charger 36 as a charging unit, a developing unit 37 as a developing unit, and transfer paper. A cassette 38, a paper feed roller 39, a registration roller 40, a transfer charger 41 as a transfer means, a separation charger 42, a transport belt 43, a fixing device 44, a paper discharge tray 45, and a cleaner 46 as a cleaning means.
The semiconductor laser 31, the rotary polygon mirror 32, the imaging lens 34, and the mirror 35 constitute an exposure unit 49.

  The photoreceptor 1 is mounted on the laser printer 30 so as to be rotatable in the direction of an arrow 47 by a driving unit (not shown). A laser beam 33 emitted from the semiconductor laser 31 is repeatedly scanned in the longitudinal direction (main scanning direction) with respect to the surface of the photoreceptor 1 by the rotary polygon mirror 32. The imaging lens 34 has f-θ characteristics, and the laser beam 33 is reflected by the mirror 35 to form an image on the surface of the photosensitive member 1 for exposure. By scanning the laser beam 33 as described above to form an image while rotating the photoconductor 1, an electrostatic latent image corresponding to image information is formed on the surface of the photoconductor 1.

  The corona charger 36, the developing device 37, the transfer charger 41, the separation charger 42 and the cleaner 46 are provided in this order from the upstream side to the downstream side in the rotation direction of the photosensitive member 1 indicated by an arrow 47.

  The corona charger 36 is provided on the upstream side of the image forming point of the laser beam 33 in the rotation direction of the photoconductor 1 and uniformly charges the surface of the photoconductor 1. Therefore, the laser beam 33 exposes the surface of the photosensitive member 1 that is uniformly charged, and a difference occurs between the charged amount of the portion exposed by the laser beam 33 and the charged amount of the portion not exposed. Electrostatic latent image is formed.

  The developing device 37 is provided on the downstream side in the rotation direction of the photosensitive member 1 with respect to the image forming point of the laser beam 33, supplies toner to the electrostatic latent image formed on the surface of the photosensitive member 1, and converts the electrostatic latent image into toner. Develop as an image. The transfer paper 48 accommodated in the transfer paper cassette 38 is taken out one by one by the paper feed roller 39 and is given to the transfer charger 41 by the registration roller 40 in synchronism with the exposure of the photoreceptor 1. The toner image is transferred onto the transfer paper 48 by the transfer charger 41. A separation charger 42 provided in the vicinity of the transfer charger 41 discharges the transfer paper onto which the toner image has been transferred and separates it from the photoreceptor 1.

  The transfer paper 48 separated from the photoreceptor 1 is conveyed to the fixing device 44 by the conveying belt 43, and the toner image is fixed by the fixing device 44. The transfer paper 48 on which the image is formed in this manner is discharged toward the paper discharge tray 45. In addition, after the transfer paper 48 is separated by the separation charger 42, the photoreceptor 1 that continues to rotate further cleans foreign matters such as toner and paper dust remaining on the surface by the cleaner 46. The photoreceptor 1 whose surface has been cleaned by the cleaner 46 is neutralized by a static eliminator (static elimination lamp) 50 provided together with the cleaner 46, and is further rotated to start a series of image forming operations starting from the charging of the photoreceptor 1. Is repeated.

  Therefore, according to the present invention, there is provided an image forming apparatus comprising the electrophotographic photosensitive member according to the present invention, a charging unit, an exposure unit, a developing unit, and a transfer unit.

The image forming apparatus of the present invention is not limited to the configuration of the image forming apparatus shown in FIG. 4, and any electrophotographic process can be used regardless of whether it is monochrome or color as long as it can use the above photoreceptor. It can be various printers, copiers, facsimiles, multifunction machines, and the like.
The image forming apparatus of the present invention is not limited to the above-described embodiment, and various modifications and changes can be made without departing from the spirit of the present invention. Other forms are described in this specification. And can be easily understood from the description of the drawings.

  EXAMPLES Hereinafter, although this invention is demonstrated further in detail using an Example, this invention is not limited to the following description content.

Example 1
Preparation of intermediate layer 3 parts by weight of titanium oxide (trade name: Tybak TTO-D-1, manufactured by Ishihara Sangyo Co., Ltd.) and 2 parts by weight of commercially available polyamide resin (trade name: Amilan CM8000, manufactured by Toray Industries, Inc.) In addition to 25 parts by weight, dispersion treatment was performed for 8 hours with a paint shaker to prepare 3 kg of an intermediate layer forming coating solution. The obtained coating solution for intermediate layer was filled in a coating tank, and an aluminum drum-shaped support having a diameter of 30 mm and a length of 357 mm was immersed as a conductive support and then pulled up to form an intermediate layer having a thickness of 1 μm.

Preparation of charge generation layer Next, 1 weight of titanyl phthalocyanine having an X-ray diffraction spectrum in which the Bragg angle (2θ ± 0.2 °) of CuKα1.541Å as a charge generation material exhibits a main peak at 27.3 ° 1 part by weight of butyral resin (trade name: ESREC BM-2, manufactured by Sekisui Chemical Co., Ltd.) as a binder resin and binder resin are mixed with 98 parts by weight of methyl ethyl ketone and dispersed for 8 hours with a paint shaker for forming a charge generation layer. 3 liters of coating solution was prepared.
The obtained coating solution for forming the charge generation layer is applied to the surface of the undercoat layer previously provided in the same manner as in the case of forming the undercoat layer, and naturally dried to form a charge generation layer having a thickness of 0.3 μm did.

Preparation of Charge Transport Layer Commercially available polytetrafluoroethylene (PTFE) particles, Lubron L-2 (manufactured by Daikin Industries, Ltd., primary particle size 200 to 300 nm) 200 g was sealed in a 1 L polypropylene container, and normal temperature and normal humidity ( Under 25 ° C./50%), γ rays from cobalt 60 were irradiated in the atmosphere at 150 kGy. When the oxygen composition ratio in the crosslinked PTFE fine particles after γ-ray irradiation was evaluated using a fluorescent X-ray apparatus (manufactured by Rigaku Denki Co., Ltd., ZSX-primAsII) under the condition of 30 kV-100 mA, the oxygen atom composition ratio was 1. It was found that oxygen-containing crosslinked PTFE fine particles of 05% (also referred to as oxygen-containing fluorine-based fine particles) were obtained.

The charge transport material is then represented by the following formula:

Compound (1) (T2269: manufactured by Tokyo Chemical Industry Co., Ltd.) 100 parts by weight, polycarbonate resin (TS2050: manufactured by Teijin Chemicals Co., Ltd.) 180 parts by weight, and 30 parts by weight of the crosslinked PTFE fine particles after γ-ray irradiation were mixed, and tetrahydrofuran was used as a solvent. After preparing a suspension having a solid content of 21% by weight, a wet-emulsifying and dispersing apparatus Microfluidizer M-110P apparatus was used, and a 5-pass operation was performed under the conditions of a set pressure: 100 MPa, and coating for forming a charge transport layer was performed. 3 kg of liquid was prepared. This charge transport layer forming coating solution was applied to the surface of the charge generation layer previously provided by an immersion method and dried at 120 ° C. for 1 hour to form a charge transport layer having a thickness of 28 μm. In this way, the multilayer photoreceptor shown in FIG. 1 was produced.

Example 2
In the same manner as in Example 1, an intermediate layer and a charge generation layer were prepared.
Thereafter, Example 2 was performed in the same manner as Example 1 except that oxygen-containing fluorine-based fine particles irradiated with 400 kGy by the same irradiation method as Example 1 were used as PTFE fine particles at the time of preparing the charge transport layer forming coating solution. A multilayer photoreceptor was prepared.
The oxygen atom composition ratio in the crosslinked PTFE fine particles after γ-ray irradiation was evaluated in the same manner as in Example 1. As a result, it was found that oxygen-containing crosslinked PTFE fine particles having an oxygen atom composition ratio of 1.55% were obtained.

Example 3
In the same manner as in Example 1, an intermediate layer and a charge generation layer were prepared.
Thereafter, the laminate of Example 3 was used in the same manner as in Example 1 except that the crosslinked PTFE fine particles irradiated with 700 kGy by the same γ-ray irradiation method as in Example 1 were used when preparing the coating liquid for forming the charge transport layer. A photoconductor was prepared.
As a result of evaluating the oxygen atom composition ratio in the crosslinked PTFE fine particles after γ-ray irradiation in the same manner as in Example 1, it was found that oxygen-containing crosslinked PTFE fine particles having an oxygen atom composition ratio of 2.28% were obtained.

Example 4
In the same manner as in Example 1, an intermediate layer and a charge generation layer were prepared.
Preparation of charge transport layer 30 ml of glass ampule was charged with 5 ml of acetone and 0.2 ml of tetrafluoroethylene monomer (TFE) (solidified once in a glass ampule with liquid nitrogen and measured by the volume of the liquid when dissolved), A mixed solution having a TFE of 4 vol% was prepared. The solution was cooled to −78 ° C. by immersing in a dry ice-methanol mixture, and the solution was irradiated with 60 kGy of gamma rays from cobalt 60 in a vacuum, then returned to room temperature, and polytetrafluoroethylene (PTFE) fine particles were collected. A dispersion was obtained. The dispersion was cooled again to −78 ° C. and again irradiated with γ rays, and the production of the crosslinked PTFE fine particle dispersion by concentrating acetone was repeated, whereby a 20 wt% crosslinked PTFE fine particle dispersion (0. 5 kg) was obtained.
The obtained particle diameter was 0.3 μm. The obtained crosslinked PTFE fine particle liquid was dried and the oxygen atom composition ratio was evaluated in the same manner as in Examples 1 to 3. As a result, oxygen-containing crosslinked PTFE fine particles having an oxygen atom composition ratio of 1.73% were obtained. I found out.

  Next, 100 parts by weight of the charge transport material (compound (1) (T2269: manufactured by Tokyo Chemical Industry Co., Ltd.)) used in Example 1 and 180 parts by weight of a polycarbonate resin (TS2050: manufactured by Teijin Chemicals) are obtained by the above method. After mixing 156 parts by weight of the crosslinked PTFE fine particle dispersion and preparing a suspension (1.5 kg) having a solid content of 21% by weight using tetrahydrofuran as a solvent, a multilayer photoreceptor was obtained in the same manner as in Example 1. .

Example 5
In the same manner as in Example 1, an intermediate layer and a charge generation layer were prepared.
Preparation of Charge Transport Layer A photoconductor was obtained in the same manner as in Example 4 except that 10 ml of acetone and 0.1 ml of TFE were added when the crosslinked PTFE dispersion was prepared. The obtained crosslinked PTFE fine particles had a particle size of 0.15 μm. Further, when the oxygen atom composition ratio in the particles was evaluated in the same manner as in Example 4, it was found that oxygen-containing crosslinked PTFE fine particles having an oxygen atom composition ratio of 1.7% were obtained.

Example 6
A laminated photoreceptor was obtained in the same manner as in Example 1 except that KTL-1N (manufactured by Kitamura Co., Ltd., primary particle diameter: 2 μm) was used as the PTFE fine particles to be contained in the charge transport layer.
The oxygen atom composition ratio of the crosslinked PTFE fine particles after γ-ray irradiation used at that time was evaluated in the same manner as in Example 4. As a result, oxygen-containing crosslinked PTFE fine particles having an oxygen atom composition ratio of 1.1% were obtained. I understood.

Example 7
Except that the PTFE fine particles used in the examples were previously pulverized (primary particle size: 0.8 μm) using a high-speed dry pulverizer: NanoJet Mizer, Aisin Nanotechnology Co., Ltd. A photoconductor was obtained in the same manner.
When the oxygen atom composition ratio of the crosslinked PTFE fine particles after γ-ray irradiation used at that time was evaluated in the same manner as in Example 4, oxygen-containing crosslinked PTFE fine particles having an oxygen atom composition ratio of 1.4% were obtained. I understood.

Example 8
In the same manner as in Example 4, after preparing the intermediate layer and the charge generation layer, a crosslinked PTFE fine particle suspension was obtained.
Next, 100 parts by weight of the charge transport material (compound (1) (T2269: manufactured by Tokyo Chemical Industry Co., Ltd.)) used in Example 4 and 180 parts by weight of a polycarbonate resin (TS2050: manufactured by Teijin Chemicals Limited) were obtained by the above method. After mixing 21.5 parts by weight of the crosslinked PTFE fine particle dispersion and preparing a suspension (1.5 kg) having a solid content of 21% by weight using tetrahydrofuran as a solvent, a laminated photoreceptor is prepared in the same manner as in Example 4. Obtained.

Example 9
In the same manner as in Example 4, after preparing the intermediate layer and the charge generation layer, a crosslinked PTFE fine particle suspension was obtained.
Next, 100 parts by weight of the charge transport material (compound (1) (T2269: manufactured by Tokyo Chemical Industry Co., Ltd.)) used in Example 4 and 180 parts by weight of a polycarbonate resin (TS2050: manufactured by Teijin Chemicals Limited) were obtained by the above method. After mixing 106 parts by weight of the crosslinked PTFE fine particle dispersion and preparing a suspension (1.5 kg) having a solid content of 21% by weight using tetrahydrofuran as a solvent, a multilayer photoreceptor was obtained in the same manner as in Example 4. .

Example 10
In the same manner as in Example 4, after preparing the intermediate layer and the charge generation layer, a crosslinked PTFE fine particle suspension was obtained.
Next, 100 parts by weight of the charge transport material (compound (1) (T2269: manufactured by Tokyo Chemical Industry Co., Ltd.)) used in Example 4 and 1800 parts by weight of a polycarbonate resin (TS2050: manufactured by Teijin Chemicals Limited) were obtained by the above method. After mixing 230 parts by weight of the crosslinked PTFE fine particle dispersion and preparing a suspension (1.5 kg) having a solid content of 21% by weight using tetrahydrofuran as a solvent, a laminated photoreceptor was obtained in the same manner as in Example 4. .

Example 11
In the same manner as in Example 2, an intermediate layer and a charge generation layer were prepared.
Thereafter, oxygen-containing fluorine-based fine particles irradiated with 400 kGy by the same irradiation method as in Example 2 were used as PTFE fine particles at the time of preparing the charge transport layer forming coating solution, and then the compound (1) 100 wt. Part (T2269: manufactured by Tokyo Chemical Industry Co., Ltd.), 180 parts by weight of polycarbonate resin (TS2050: manufactured by Teijin Chemicals Co., Ltd.) and 61.5 parts by weight of the above-mentioned γ-irradiated PTFE fine particles were mixed and laminated type in the same manner as in Example 2. A photoreceptor was obtained.

Example 12
In the same manner as in Example 2, an intermediate layer and a charge generation layer were prepared.
Thereafter, oxygen-containing fluorine-based fine particles irradiated with 400 kGy by the same irradiation method as in Example 2 were used as PTFE fine particles at the time of preparing the charge transport layer forming coating solution, and then the compound (1) (T2269) as the charge transport material. : Tokyo Chemical Industry Co., Ltd.) 100 parts by weight, polycarbonate resin (TS2050: manufactured by Teijin Chemicals Co., Ltd.) 180 parts by weight, and 104 parts by weight of the above-mentioned γ-irradiated PTFE fine particles were mixed. Got.

Example 13
A 15 μm first charge transport layer was prepared in the same manner as in Example 1 except that the PTFE fine particles were not added to the charge transport layer. Thereafter, as the second charge transport layer, a 10 μm second charge transport layer having the same component ratio as in Comparative Example 7 was applied and dried at 120 ° C. to form a photoreceptor.

Comparative Example 1
A photoreceptor was prepared in the same manner as in Example 1 except that PTFE fine particles were not added to the charge transport layer.

Comparative Example 2
A photoconductor was prepared in the same manner as in Example 1 except that the same PTFE fine particles as in Example 1 were used and γ-ray irradiation was not performed.
The evaluation result of the oxygen atom composition ratio in the particles used at that time was 0.55%, but the value of 0.55% obtained here is the value of white X-rays measured by fluorescent X-rays. It was a background level, and it was actually judged that oxygen was not contained.

Comparative Example 3
A photoconductor in the same manner as in Example 1 except that the same PTFE fine particles as in Example 1 were used (no γ-irradiation) and 1 part by weight of GF-400 (manufactured by Toagosei Co., Ltd.) was added as a fine particle dispersant. It was created.

Comparative Example 4
A photoconductor was prepared in the same manner as in Example 1 except that the same PTFE fine particles as in Example 1 were irradiated with 1000 kGy of γ rays.
The oxygen atom composition ratio of the crosslinked PTFE fine particles after γ-ray irradiation used at that time was evaluated in the same manner as in Example 4. As a result, oxygen-containing crosslinked PTFE fine particles having an oxygen atom composition ratio of 3.31% were obtained. I found out.

Comparative Example 5
A photoconductor was prepared in the same manner as in Comparative Example 3 except that tetrafluoroethylene perfluoroalkyl (PFA) MP101 (Mitsui DuPont Fluorochemical Co., Ltd.) was used as the fluorine-based fine particles.
The evaluation result of the oxygen atom composition ratio in the PFA particles used at that time was 0.70%, and the value of 0.70% obtained here is white X-ray at the time of measurement by fluorescent X-rays. It was determined that there was actually no oxygen content.

Comparative Example 6
In the same manner as in Example 4, after preparing the intermediate layer and the charge generation layer, a crosslinked PTFE fine particle suspension was obtained.
Next, 100 parts by weight of the charge transport material (compound (1) (T2269: manufactured by Tokyo Chemical Industry Co., Ltd.)) used in Example 4 and 180 parts by weight of a polycarbonate resin (TS2050: manufactured by Teijin Chemicals Limited) were obtained by the above method. After mixing 8 parts by weight of the crosslinked PTFE fine particle dispersion and preparing a suspension having a solid content of 21% by weight using tetrahydrofuran as a solvent, a multilayer photoreceptor was obtained in the same manner as in Example 4.

Comparative Example 7
In the same manner as in Example 2, an intermediate layer and a charge generation layer were prepared.
Thereafter, oxygen-containing fluorine-based fine particles irradiated with 400 kGy by the same irradiation method as in Example 2 were used as PTFE fine particles at the time of preparing the charge transport layer forming coating solution, and then the compound (1) 100 wt. Parts (T2269: manufactured by Tokyo Chemical Industry Co., Ltd.), polycarbonate resin (TS2050: manufactured by Teijin Chemicals Co., Ltd.), 180 parts by weight, and 151 parts by weight of the above-mentioned γ-irradiated PTFE fine particles were mixed. Got.

[Evaluation]
1. Evaluation of primary particle diameter of filler particles The primary particle diameter of the filler was measured using a scanning electron microscope (manufactured by Hitachi, Ltd., S4800).

2. Particle size evaluation of charge transport layer coating solution In Examples 1 to 13 and Comparative Examples 2 to 7, the stability of the filler dispersion state in the charge transport layer coating solution used was measured using a laser diffraction particle size distribution measuring device (Microtrac MT). -3000II, manufactured by Nikkiso Co., Ltd.).
Immediately after the dispersion, 40 cc of each coating solution was transferred into a sample tube (50 cc), and the particle size distribution (D50) after stirring with a stirrer (100 rpm, 15 h) was measured and compared.
VG (very good): very good (D50 <1.0 μm)
G (good): Good (1.0 ≦ D50 <3.0 μm)
NB (not bad): Level at which actual use is possible (3.0 ≦ D50 <6.0 μm)
B (bad): Unusable (6.0μm <D50)

  An image forming process is carried out by mounting the photoconductor produced in the example / comparative example on a test copier modified from a digital copier (trade name: MX-2600, manufactured by Sharp Corporation) for the obtained photoconductor. A surface potential meter (manufactured by TREC JAPAN, model 344) was provided so as to measure the surface potential of the photoconductors of the photoconductors, and the electrical characteristics and image quality of each photoconductor were evaluated. The light source used was a laser beam having a wavelength of 780 nm.

3. Electrical Evaluation First, using the copying machine, the surface potential of the photosensitive member at the developing portion, specifically, the surface potential VL of the photosensitive member at the black background during exposure was measured in order to check the sensitivity of the photosensitive member. These surface potentials VL were measured in the normal temperature / normal humidity (abbreviated as “N / N”) environment of 25 ° C./50% RH (relative humidity) at the initial stage and immediately after 100 k-sequential repeated copying.

4). Image Evaluation After the photoconductor is mounted on the photocopier, 10 plain images are printed, and the black dot generation periodicity per hard copy (A3 version) matches the cycle of the photoconductor. The number of poti (0.4 mm or more in diameter) was counted, and the result was judged according to the following criteria.
VG: The occurrence frequency of image defects is 3 or less per image in all hard copies. G: The occurrence frequency of image defects is 4 to 7 per image in all hard copies, but there is no practical problem. NB: All Hard copy has an image defect occurrence frequency of 8 to 10 / sheet, but at a practical level

B: There are one or more hard copies with an image defect occurrence frequency of 11 / sheet or more, which is problematic in practice.

5). Film slick evaluation Changes in the film thickness of the photoconductor before and after the actual shooting of 100k sheets were measured using an eddy current film thickness meter (Fischer), and film slicking per 100k rotation of the photoconductor on the copying machine. In terms of the amount (Δ), the evaluation was based on the relative level compared with the photoreceptor without filler.
VG: Very good improvement level (Δ <0.5 μm / 100 k rotation)
G: Good level of improvement (less than 0.5 ≦ Δ <1.0 μm / 100k rotation)
NB: Improvement is seen (1.0 ≦ Δ <2.0 μm / less than 100k times)
B: No improvement is observed (2.0 μm ≦ Δ)

For the photoconductor of Comparative Example 2, the image quality deterioration due to the aggregation of fluorine fine particles in the film was remarkable from the beginning, and the film slippage amount (Δ) could not be determined after 100k sheets were actually captured.
The results obtained by the above evaluation are shown in Table 1 together with the primary particle diameter (μm) of the filler particles, the oxygen composition ratio in the filler particles, the amount of filler added, and the like.

Comprehensive evaluation The evaluation in the above evaluation items 1 to 5 was comprehensively evaluated based on the following criteria.
VG: Good for each item, very good level with no problem in actual use.
G: Although deterioration of 1-2 items is seen, it is a satisfactory level without problems in actual use.
NB: Deterioration of 3 or more items, but no significant deterioration, practically usable level.
B: There are a plurality of markedly deteriorated items, and it is difficult to actually use.

  From the above table, the surface layer of the electrophotographic photosensitive member contains oxygen-containing fluorine-based fine particles, and the oxygen-containing composition ratio in the fine particles is 0.9- 3.0 atomic%, and the oxygen-containing fluorine-based fine particles have a median diameter (D50) of primary particles of 0.1 to 2 μm, and the content of the oxygen-containing fluorine-based fine particles is 1.0 to 40. % Of the photoreceptors of Examples 1 to 13 were superior to the photoreceptors of Comparative Examples 1 to 7 in all evaluation items.

  According to the present invention, by containing fluorine-based fine particles polymerized by a specific preparation method in the uppermost layer of the electrophotographic photoreceptor, the dispersion stability as the photoreceptor coating liquid is high and the wear resistance is high. An electrophotographic photoreceptor that is electrically stable for a long period of time and an image forming apparatus provided with the photoreceptor are provided.

DESCRIPTION OF SYMBOLS 1, 2 Electrophotographic photoreceptor 11 Conductive base | substrate 12 Charge generation layer 13, 13A, 13B Charge transport layer 14 Photosensitive layer 15 Undercoat layer (intermediate layer)
30 Laser printer (image forming device)
DESCRIPTION OF SYMBOLS 31 Semiconductor laser 32 Rotating polygon mirror 33 Laser beam 34 Imaging lens 35 Mirror 36 Corona charger 37 Developer 38 Transfer paper cassette 39 Paper feed roller 40 Registration roller 41 Transfer charger 42 Separation charger 43 Conveyor belt 44 Fixer 45 Exhaust Paper tray 46 Cleaner 47 Arrow 48 Transfer paper 49 Exposure means 50 Static eliminator

Claims (5)

  In an electrophotographic photoreceptor having a photosensitive layer formed on a conductive substrate, the surface layer contains oxygen-containing fluorine-based fine particles, and the oxygen-containing composition ratio in the fine particles is a composition analysis by fluorescent X-rays. The electrophotographic photosensitive member according to claim 1, wherein the proportion is 0.9 to 3.0 atomic% of the whole fine particles. The oxygen-containing fluorine-based fine particles are those obtained by irradiating polytetrafluoroethylene fine particles with γ rays from cobalt 60 in the atmosphere, or using tetrafluoroethylene monomer as a raw material, and the following steps:
(A) a step of polymerizing the tetrafluoroethylene monomer by irradiating a mixed solution of the tetrafluoroethylene monomer and acetone with ionizing radiation to make the mixed solution into an acetone dispersion of polytetrafluoroethylene in a gel state;
(B) cross-linking the polytetrafluoroethylene by irradiating the acetone dispersion of polytetrafluoroethylene with ionizing radiation to form a fine particle suspension; and optional (c) from the fine particle suspension. Isolating oxygen-containing fluorine-based fine particles by separation and drying;
The electrophotographic photosensitive member according to claim 1, which is obtained by:   The electrophotographic photosensitive member according to claim 1, wherein the oxygen-containing fluorine-based fine particles contain oxygen having a composition ratio of 1.0 to 3.0 atomic%.   The electrophotographic photosensitive member according to claim 1, wherein the oxygen-containing fluorine-based fine particles have a median diameter (D50) of primary particles of 0.1 to 2 μm.   5. The electrophotographic photosensitive member according to claim 1, charging means for charging the electrophotographic photosensitive member, and exposure of the charged electrophotographic photosensitive member to form an electrostatic latent image. An exposure unit; a developing unit that develops the electrostatic latent image with toner to form a toner image; a transfer unit that transfers the toner image onto a recording material; and the transferred toner image on the recording material. An image forming apparatus comprising a fixing unit for fixing.