JP2016148766A - Electrophotographic photoreceptor, inspection method of the same, and image forming apparatus including electrophotographic photoreceptor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrophotographic photoreceptor capable of forming stable and high-quality images over a long period of time, and conditions for manufacturing the photoreceptor.SOLUTION: The electrophotographic photoreceptor comprises a multilayer photosensitive layer having a charge generating layer containing at least a charge generating substance and a charge transporting layer containing a charge transporting substance, layered in this order on a conductive substrate, or a monolayer photosensitive layer containing a charge generating substance and a charge transporting substance layered on a conductive substrate. The outermost surface layer of the electrophotographic photoreceptor contains at least polytetrafluoroethylene ethylene particles. The outermost surface layer contains high boiling point solvents having a boiling point of 100 to 160°C used as a sub-solvent in such a manner that, in the comparison of integral intensities by an analysis of a residual solvent amount in the outermost surface layer by use of thermal desorption gas chromatography, an integral intensity ratio of whole high boiling point solvents is 10 to 70% with respect to the integral intensity of tetrahydrofuran-containing 2,6-di-t-butyl-4-methylphenol used as a main solvent for the coating liquid to form the outermost surface layer.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an electrophotographic photosensitive member, an inspection method thereof, and an image forming apparatus including the electrophotographic photosensitive member. More specifically, in the present invention, the surface layer of the photoreceptor contains fine particles and a high-boiling solvent-containing dispersant as a dispersant thereof, and another high-boiling solvent as a sub-solvent of the surface layer coating liquid. The present invention relates to an electrophotographic photoreceptor produced using a coating for forming a surface layer, a manufacturing inspection method thereof, and an image forming apparatus provided with the electrophotographic photoreceptor.

  In 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, an image is formed 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 to form an image.

However, during the transfer operation by the transfer unit, the toner on the surface of the photoconductor is not transferred to the recording paper and transferred, 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, and the remaining electrostatic latent image is lost.

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 electrophotographic photoreceptors include inorganic photoconductive materials and organic photoconductive materials (hereinafter referred to as organic photoconductor (OPC)). Since the sensitivity and durability of the body have been improved, organic photoreceptors are often used at present.

  In recent years, the electrophotographic photosensitive member has been mainly composed of a laminated type photosensitive member in which the photosensitive layer is functionally separated into a charge generation layer containing a charge generation material and a charge transport layer containing a charge transport material. ing. In many cases, a charge transport layer in which a charge transport material having a charge transport ability 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.

  A drawback of organic photoreceptors is the wear of the surface associated with the slidable printing of cleaners and the like around the photoreceptor due to the nature of organic materials. As a means for overcoming this drawback, it has been attempted to improve the mechanical properties of the material of the photoreceptor surface.

  As efforts so far, a protective layer is provided on the outermost surface layer of the photoreceptor 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-1-172970: 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). Also, as a feature of fluorine-based particles, due to the high lubrication function derived from the material, fluorine-based particles not only improve the mechanical properties of the photoconductor as a filler, but also provide lubricity and contact during the photoconductor process. Reducing the frictional force with the member to be used also contributes to improving the printing durability of the surface of the photoreceptor.

  On the other hand, fluorine-based fine particles, for example, polytetrafluoroethylene (PTFE) fine particles have an excellent lubricating function as a material, while having no polarity, there is a disadvantage that the cohesive force of particles is very large and dispersibility is extremely poor. is there. Therefore, when dispersing PTFE fine particles for use in a photoreceptor, it has been proposed to use a dispersant (for example, JP 2011-1118054 A: Patent Document 4), but as a result, the electrical characteristics of the photoreceptor are deteriorated. I will let you.

JP-A-1-23259 JP-A-1-172970 Japanese Patent No. 3416310 JP 2011-118054 A

As described above, when fluorine fine particles are added to the photoreceptor surface layer, the use of a dispersant is unavoidable, and the electrical characteristics of the photoreceptor are deteriorated by the addition of the dispersant. Further, high-boiling solvents tend to remain in the system even after drying, while many of them have high affinity with the above-mentioned fine particle dispersant, and are effective in improving dispersibility and dispersion stability.
Accordingly, an object of the present invention is to provide an electrophotographic photosensitive member having stable photosensitive member electrical characteristics over a long period of time despite the inclusion of a dispersant that causes deterioration of electrical characteristics.

  As a result of intensive studies to solve the above problems, the present inventor added an electrophotographic photosensitive member having a photosensitive layer formed on a conductive substrate, particularly as a high-boiling solvent or a sub-solvent usually contained in a dispersant. By including the residual amount of the high boiling point solvent in the outermost surface layer of the photoreceptor after forming the photosensitive layer produced using the coating solution for forming the surface layer of the photoreceptor containing the high boiling point solvent, in a specific range, The inventors have found that it is possible to provide a photoconductor that is excellent in wear and is electrically stable, and has completed the present invention.

Thus, according to the present invention, on a conductive substrate, a charge generating layer containing at least a charge generating material and a charge transport layer containing a charge transport material are laminated in this order, or on a conductive substrate. An electrophotographic photosensitive member in which a single-layer type photosensitive layer containing a charge generation material and a charge transport material is laminated,
The outermost surface layer of the electrophotographic photosensitive member contains at least polytetrafluoroethyleneethylene particles, and the outermost surface layer is formed in an integrated intensity comparison by analyzing the amount of residual solvent using thermal desorption gas chromatography of the outermost surface layer. High boiling point solvent having a boiling point of 100 to 160 ° C. used as a secondary solvent with respect to the integrated strength of tetrahydrofuran-containing 2,6-di-t-butyl-4-methylphenol used as a main solvent in the coating liquid The electrophotographic photosensitive member is characterized by containing an integrated intensity ratio of 10 to 70%.

  Further, according to the present invention, there is provided the electrophotographic photosensitive member, wherein the analysis of the residual solvent amount by the thermal desorption gas chromatography is an analysis based on an integrated intensity comparison of the residual solvent amount at a thermal desorption temperature of 200 ° C. or less. .

  Further, according to the present invention, in the analysis of the amount of residual solvent by the thermal desorption gas chromatography, the electrophotographic photosensitive member, wherein the outermost surface layer includes an integrated intensity ratio of 10 to 40% including a high boiling point solvent. Provided.

  Further, according to the present invention, in the analysis of the residual solvent amount by the thermal desorption gas chromatography, the electrophotographic photosensitive member, wherein the outermost surface layer includes an integrated intensity ratio of 10 to 20% including a high-boiling solvent. Provided.

  According to the present invention, there is also provided a charge transport layer coating solution comprising a charge transport material, a binder resin, polytetrafluoroethylene particles, a dispersant, and a 0 to 45% by weight toluene-containing tetrahydrofuran solution. Provided.

  In addition, according to the present invention, a charge transport layer coating solution containing a charge transport material, a binder resin, polytetrafluoroethylene particles, a dispersant, and a 0 to 45% by weight toluene-containing tetrahydrofuran solution is used. There is provided a method for producing an electrophotographic photoreceptor containing the above-mentioned high-boiling solvent.

  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.

  The inventors of the present invention use the high-boiling point used as the high-boiling solvent and auxiliary solvent derived from the dispersing agent containing the specific polymer, in which the outermost surface layer of the electrophotographic photoreceptor according to the present invention contains specific fine particles and a high-boiling solvent. The total remaining amount of the solvent was 2,6-ditetrahydrofuran containing tetrahydrofuran as a main solvent in the coating solution for forming the outermost surface layer in the analysis of the remaining solvent amount using thermal desorption gas chromatography of the outermost surface layer. An electrophotographic photoreceptor having high wear resistance and being electrically stable over a long period of time by including in a specific range with respect to the integrated intensity of t-butyl-4-methylphenol, and image formation including the photoreceptor It became possible to provide a device.

1 is a schematic cross-sectional view showing a configuration of an electrophotographic photosensitive member according to Embodiment 1 of the present invention. FIG. 5 is a schematic cross-sectional view showing a configuration of an electrophotographic photosensitive member according to Embodiment 2 of the present invention. It is a schematic cross section which shows the structure of the electrophotographic photoreceptor which concerns on Embodiment 3 of this invention. FIG. 6 is a schematic cross-sectional view showing a configuration of an image forming apparatus according to Embodiment 4 of the present invention.

  In the electrophotographic photosensitive member of the present invention (hereinafter also referred to as a photosensitive member), the outermost surface layer of the electrophotographic photosensitive member in which a photosensitive layer is provided on a conductive substrate has specific fine particles, that is, polytetrafluoroethylene (PTFE) particles. And a specific polymer containing a high-boiling solvent, that is, a high-boiling solvent derived from a dispersant containing a fluorine-containing copolymer and the remaining amount of the other high-boiling solvent are residual solvents using the thermal desorption gas chromatography of the outermost surface layer. Included in a specific range with respect to the integrated intensity of tetrahydrofuran-containing 2,6-di-t-butyl-4-methylphenol used as a main solvent in the coating solution for forming the outermost surface layer in the analysis of the amount It is characterized by that.

  In the photoreceptor according to the present invention, a photosensitive layer is provided on a conductive substrate, and the photosensitive layer can be 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 separately as an outermost surface layer. Furthermore, the charge transport layer may be composed of a first charge transport layer and a second charge transport layer, and the second charge transport layer may be the outermost surface layer. Moreover, it is possible to further stabilize electrically by using an undercoat layer.

The term “high boiling point solvent” used in the present invention is included in the dispersant for PTFE particles used in the charge transport layer coating solution or other solvent for the charge transport layer coating solution. It means a solvent having a boiling point between ° C.
Examples of such high-boiling solvents include methyl isobutyl ketone, n-butyl acetate, s-butyl acetate, pentyl acetate, isopentyl acetate, cyclohexanone, toluene, o-xylene, m-xylene and p-xylene, N, N -Dimethylformamide may be used alone or a mixed solvent thereof.

Moreover, a fluorine-containing copolymer is mentioned as a specific polymer which said dispersing agent for PTFE particles contains.
As the above-mentioned fluorine-containing copolymer, a fluorine-based graft polymer in which a matrix-compatible side chain is arranged on a fluorine-based main chain, for example, GF-400 manufactured by Toagosei Co., Ltd .; a fluorine-based segment and a compatible segment are alternately arranged A block copolymer type, for example, F-200 manufactured by NOF Corporation; an oligomer type in which a fluororesin is suspended as a pendant on a compatible resin, such as F-561 manufactured by Dainippon Ink, Inc., and the like.
Accordingly, the dispersant for PTFE particles contained in the outermost surface layer of the electrophotographic photoreceptor according to the present invention includes a dispersant containing any one of the above-mentioned fluorine-containing copolymer and the above-mentioned high boiling point solvent.

  The outermost surface layer of the electrophotographic photoreceptor according to the present invention is subjected to analysis by thermal desorption chromatography, and the residual amount of the high boiling point solvent contained in the dispersant for PTFE particles contained in the outermost surface layer is measured. . In this analysis, a section prepared by peeling and cutting off the outermost surface layer for the analysis is used as a sample.

  The outermost surface layer of the electrophotographic photosensitive member according to the present invention was prepared by using tetrahydrofuran (as the main solvent in the outermost surface layer coating solution) in the integrated intensity comparison of the residual solvent amount analysis by thermal desorption gas chromatography using the above-mentioned data. (THF) -containing 2,6-di-t-butyl-4-methylphenol (butylated hydroxytoluene: BHT) with respect to the integrated intensity, which includes an integrated intensity ratio of the high boiling point solvent of 10 to 70%. .

10-40% is preferable and, as for the ratio with respect to the said BHT integral intensity | strength of the said high boiling point solvent which the said outermost surface layer contains, 10-20% is more preferable.
A high temperature heat treatment or a long time heat treatment in which the total content of the high boiling point solvent with respect to BHT is less than 10% is used for the drying of the outermost surface layer of the electrophotographic photoreceptor according to the present invention. This is also not preferable because it causes deterioration of components.

  In addition, when the drying condition at the production of the outermost surface layer of the electrophotographic photosensitive member according to the present invention is such that the total content of the high-boiling solvent with respect to BHT exceeds 70%, the outermost layer of the photosensitive member is used. Insufficient drying of the surface layer, and the high boiling point solvent remains in the outermost surface layer, sufficient hardness of the outermost surface layer cannot be obtained, and trapping by the remaining high boiling point solvent occurs, resulting in good electrical characteristics. Since it cannot be obtained, it is not preferable.

By adding an appropriate amount of a dispersant of a solvent having a boiling point of 100 to 160 ° C. and a fluorine-containing graft copolymer to the coating solution for the surface layer of the photosensitive layer containing tetrahydrofuran as a main solvent, polytetrafluoro in the coating film is obtained. It is possible to maintain good electrical characteristics as a photoreceptor while maintaining the dispersibility of the ethylene particles.
An organic solvent having a boiling point of less than 100 ° C. is not suitable in terms of good solvent and storage stability of the dispersant, resulting in insufficient dispersibility of fine particles.
Therefore, using a solvent having a boiling point of 100 to 160 ° C. as a secondary solvent and a coating solution for the surface layer together with THF is excellent in the affinity between the dispersant and the high boiling point solvent, so that even better dispersibility is obtained. It is preferable to maintain.
In addition, when a solvent having a boiling point higher than 160 ° C. is used, since the boiling point is clearly higher than the actual photosensitive member drying temperature, the residual amount of the solvent after drying is greatly increased. The impact will be significantly worsened.

  In order to keep the amount of the high-boiling solvent contained in a desired range, it is necessary to control the drying conditions after the application of the coating liquid, or the amount of dispersant added in the first place. That is, the integral intensity ratio by the desired analysis is ensured by forming the photoreceptor coating film by drying at a relatively high temperature or by reducing the amount of the dispersant.

Although details are not clear, it is conceivable that the correlation between the regulation of the amount of the high boiling point solvent based on the present invention and the stability of the electrical characteristics of the photoreceptor can be obtained as follows.
That is, it is presumed that the high boiling point solvent detected (desorbed) at 200 ° C. or lower set during the analysis is contained in a certain cluster size in the photosensitive system.
On the other hand, in these solvents, it seems that there are also other solvent components that are completely dissolved in the system in a monomolecular form. Therefore, it is presumed that the desorbed solvent molecular weight defined by the present invention contributes to the electrical stability of the photoreceptor, not the amount originally added to the system.

  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 described in detail with reference to FIGS. The embodiments and examples described below are merely specific examples of the present invention, and the present invention is not limited to these.

Embodiment 1
FIG. 1 is a schematic cross-sectional view showing the configuration of the electrophotographic photoreceptor according to the first exemplary embodiment of the present invention.
The electrophotographic photoreceptor 1 according to the first embodiment (hereinafter also referred to as the photoreceptor 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 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; It is also possible to use a vapor-deposited material or a material obtained by vapor-depositing or applying a conductive compound layer such as a conductive polymer, tin oxide, or indium oxide.
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 15 (also referred to as an 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 15, 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 resin in an appropriate solvent and applying the coating solution to the surface of the conductive substrate 11. Is done.
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 this coating solution to the surface of the conductive substrate 11.

As the solvent for the undercoat layer coating solution, 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 undercoat 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 coating methods, the dip coating method, in particular, forms 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 sequentially changing speed. This method is relatively simple and excellent in terms of productivity and cost, and is therefore often used in the production of electrophotographic photoreceptors. In addition, in order to stabilize the dispersibility of a coating liquid, you may provide the coating liquid dispersion | distribution apparatus represented by the ultrasonic generator in the apparatus used for a dip coating method.

The thickness of the undercoat layer 15 is preferably 0.01 to 20 μm, more preferably 0.05 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 larger than 20 μm, it becomes 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 film thickness of the undercoat layer 15 is preferably 0.01 to 20 μm.

Charge generation layer 12
The charge generation layer 12 contains, as a main component, a charge generation material 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 They 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, a method of vacuum-depositing the charge generation material on the surface of the conductive substrate 11, or a charge generation layer coating obtained by dispersing the charge generation material in a suitable solvent. For example, a method of applying a working solution to the surface of the conductive substrate 11 is used.
Among these, a charge generation layer coating solution is prepared by dispersing a charge generation material by a conventionally known method in a binder resin solution obtained by mixing a binder resin as a binder in a solvent. A method of applying the obtained coating liquid 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 for the charge generation layer coating solution include halogenated hydrocarbons such as dichloromethane and dichloroethane, alcohols such as methanol and ethanol, ketones such as acetone, methyl ethyl ketone and cyclohexanone, and 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-dimethyl An aprotic polar solvent such as acetamide 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 configured to include 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 to 400/100. It is preferable.
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, the preferable range of the ratio W1 / W2 is preferably 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 to 5 μm, more preferably 0.1 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, the preferable range of the film thickness of the charge generation layer 12 is preferably 0.05 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.
Further, the ratio of the charge transport material and the binder resin in the charge transport layer is preferably in the range of 10/18 to 10/10 in 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 within 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.

  In addition, 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 is, for example, a charge transport material, a binder resin, the filler particles, and, if necessary, the additive in an appropriate solvent. It is formed by dissolving or dispersing to prepare a coating liquid for a charge transport layer, and applying the obtained coating liquid on the charge generation layer 12.

  As the solvent for the coating solution for the charge transport layer, generally, for example, aromatic hydrocarbons such as benzene, toluene, xylene and monochlorobenzene, halogenated hydrocarbons such as dichloromethane and dichloroethane, tetrahydrofuran, dioxane and dimethoxymethyl ether And aprotic polar solvents such as N, N-dimethylformamide. These solvents may be used alone or in combination of two or more.

In addition, a solvent such as alcohols, acetonitrile or methyl ethyl ketone may be further added to the above solvent as necessary.
Among these solvents, non-halogen organic solvents are preferably used in consideration of the global environment.

  Among them, in the present invention, tetrahydrofuran (THF) is used as the main solvent of the charge transport layer coating solution. However, THF contains 0.05 wt% of 2,6-di-tert-butyl-4-methylphenol (BHT) as an antioxidant in the solvent, and this BHT is thermally desorbed after formation of the charge transport layer. It becomes an internal standard substance when measuring the residual amount of the high boiling point solvent after the formation of the photosensitive layer as defined by gas chromatography.

  In the present invention, the main solvent of the charge transport layer coating solution is preferably a 0 to 45% by weight toluene-containing tetrahydrofuran solution from the viewpoint of the temporal dispersion stability of the coating solution.

  Thermal desorption gas chromatography is generally a widely used method for extracting and separating volatile and semi-volatile compounds from various matrices. In the present invention, it is used to selectively extract a high boiling point solvent component that leads to deterioration of characteristics from a matrix called a photoreceptor layer.

  Examples of the coating method for the charge transport 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 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.

Each of the charge transport layers 13 preferably has a thickness of 5 to 40 μm, more preferably 10 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 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 forming each layer by coating can be improved. 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 illustrated in FIG. It may be in the form of a single layer including both the generating substance and the charge transport layer, that is, 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 layers consisting of different charge transport layers 13A and 13B, and polytetrafluoroethylene particles are added to the outermost charge transport layer 13B. That is, in FIG. 3, the charge transport layer 13 includes a first charge transport layer 13A and a 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 form in which the second charge transport layer 13B contains polytetrafluoroethylene particles is shown in such a way that the content of the second charge transport layer 13B is different.
As described above, when the charge transport layer 13 is configured by laminating a plurality of layers, it is preferable that polytetrafluoroethylene particles are contained in the layer on the surface side of the charge transport layer 13.

Embodiment 4
FIG. 4 is a schematic cross-sectional view showing the configuration of the image forming apparatus 30 according to the present invention.
The image forming apparatus according to the present invention is not limited to the configuration of the image forming apparatus shown in FIG. 4, and can be electrophotographic regardless of monochrome or color as long as the photoconductor according to the present invention can be used. It can be a variety of printers, copiers, facsimiles, multifunction machines, etc. that utilize the process.
Hereinafter, the configuration and image forming operation of the laser printer 30 on which the photoreceptor 1 according to the first embodiment of the present invention is mounted will be described with reference to FIG.
The laser printer 30 illustrated in FIG. 4 is an example of the image forming apparatus 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, when the laser beam 33 exposes the surface of the photosensitive member 1 that is uniformly charged, a difference occurs between the charge amount of the portion exposed by the laser beam 33 and the charge amount of the portion that is not exposed. An 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 from the transfer paper cassette one by one by the paper feed roller 39 and is given to the transfer charger 41 in synchronism with the exposure to the photosensitive member 1 by the registration roller 40. 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 photosensitive member 1 whose surface has been cleaned by the cleaner 46 is neutralized by a neutralizing lamp (not shown) provided together with the cleaner 46 and then further rotated, and a series of image forming operations starting from the charging of the photosensitive member 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 30 according to 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. 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.

Production of Charge Generation Layer Next, titanyl phthalocyanine 1 having an X-ray diffraction spectrum in which a Bragg angle (2θ ± 0.2 °) with respect to X-ray of CuKα 1.541５４ as a charge generation material shows 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 98 parts by weight of methyl ethyl ketone are mixed and dispersed in a paint shaker for 8 hours to form a charge generation layer. 3 liters of coating solution was prepared.
The obtained coating solution for forming a charge generation layer is applied to the surface of the undercoat layer previously provided in the same manner as in the formation of the undercoat layer, and naturally dried to form a charge generation layer having a thickness of 0.3 μm. Formed.

As a charge transport material, the following formula:

100 parts by weight of a compound 1 (T2269: manufactured by Tokyo Chemical Industry Co., Ltd.), 180 parts by weight of a polycarbonate resin (TS2050: manufactured by Teijin Chemicals), Lubron L-2 (Daikin Industries, Ltd.) which is polytetrafluoroethylene (PTFE) particles GF-400 (manufactured by Toa Gosei Co., Ltd., solid content: 25% fluorine-based graft polymer, 57% methyl isobutyl ketone and n-acetate) Butyl 18%) is mixed in 2.4 parts by weight, and dispersed as a solvent in tetrahydrofuran 817 parts by weight and toluene 350 parts by weight, that is, 30% by weight toluene-containing tetrahydrofuran solution. After preparation, wet emulsifying and dispersing device Microfluidizer M-110 Microfluidi Using s manufactured device, and 5pass operations carried out under conditions of set pressure 100 MPa, the solid concentration of 21 wt% of the charge transport layer coating liquid 3Kg of surface layer coating for suspension were 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 130 ° 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.

  Hereinafter, the solid content concentration of the suspension liquid for surface layer coating in Examples and Comparative Examples is unified to 21 wt% as in Example 1. Thereby, when it coats with the same film thickness, in this example, the amount of residual THF and the amount of 2,6-di-t-butyl-4-methylphenol (BHT) contained immediately after coating film formation are It was assumed that the value was constant.

Example 2
In the same manner as in Example 1, an intermediate layer and a charge generation layer were prepared. Thereafter, the same procedure as in Example 1 was carried out except that 934 parts by weight of tetrahydrofuran and 233 parts by weight of toluene, that is, 24% by weight of a toluene-containing tetrahydrofuran solution were used as the solvent for the coating liquid for forming the charge transport layer. The photoreceptor of Example 2 was prepared.

Example 3
In the same manner as in Example 1, an intermediate layer and a charge generation layer were prepared. Thereafter, the same procedure as in Example 1 was carried out except that 1050 parts by weight of tetrahydrofuran and 117 parts by weight of toluene, that is, 11% by weight of a toluene-containing tetrahydrofuran solution were used as the solvent for the coating liquid for forming the charge transport layer. The photoreceptor of Example 3 was prepared.

Example 4
In the same manner as in Example 1, an intermediate layer and a charge generation layer were prepared. Thereafter, a photoconductor of Example 4 was prepared in the same manner as in Example 1 except that only 1167 parts by weight of tetrahydrofuran was used as the solvent for the charge transport layer forming coating solution.

Example 5
In the same manner as in Example 1, an intermediate layer and a charge generation layer were prepared. Thereafter, the same procedure as in Example 1 was performed except that 1120 parts by weight of tetrahydrofuran and 47 parts by weight of toluene, that is, a 4% by weight toluene-containing tetrahydrofuran solution were used as the solvent for the coating liquid for forming the charge transport layer. The photoreceptor of Example 5 was prepared.

Example 6
In the same manner as in Example 1, an intermediate layer and a charge generation layer were prepared. Thereafter, the same procedure as in Example 1 was performed except that 700 parts by weight of tetrahydrofuran and 467 parts by weight of toluene, that is, 40% by weight of a toluene-containing tetrahydrofuran solution were used as the solvent for the coating liquid for forming the charge transport layer. The photoreceptor of Example 6 was prepared.

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

Comparative Example 2
In the same manner as in Example 1, an intermediate layer and a charge generation layer were prepared. Thereafter, a photoreceptor of Comparative Example 2 was prepared in the same manner as in Example 1 except that 584 parts by weight of tetrahydrofuran and 583 parts by weight of toluene were used as the solvent for the coating liquid for forming the charge transport layer.

Comparative Example 3
In the same manner as in Example 1, an intermediate layer and a charge generation layer were prepared. Thereafter, the 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 110 ° C. for 1 hour to form a charge transport layer having a thickness of 28 μm.

Comparative Example 4
In the same manner as in Example 1, an intermediate layer and a charge generation layer were prepared. Thereafter, the 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 150 ° C. for 1 hour to form a charge transport layer having a thickness of 28 μm.

Comparative Example 5
In the same manner as in Example 4, an intermediate layer and a charge generation layer were prepared. Thereafter, the 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 150 ° C. for 1 hour to form a charge transport layer having a thickness of 28 μm.

Evaluation 1. Evaluation of residual amount of high boiling point solvent In the thermal desorption gas chromatography of the present invention, the thermal desorption conditions were selected to be not higher than the boiling point of BHT serving as a reference substance and not lower than the boiling point of the high boiling point solvent. That is, the surface layer peeled off from the photosensitive layer was used as a sample, the temperature was raised to 180 ° C. to 200 ° C. using EGA-PY 3030D manufactured by Frontier Lab, and the liquid nitrogen temperature (− The residual high boiling point solvent and BHT were detected and analyzed using a 7890A GC system and a 5975C mass detection system manufactured by Agilent Technologies Inc., which were set at a temperature rising condition of 40 ° C. to 180 ° C. disposed at the subsequent stage.

2. Electrical characteristics evaluation For the obtained photoconductor, the photocopier created in Example / Comparative Example is mounted on a test copier modified from a digital copier (trade name: MX-2600, manufactured by Sharp Corporation). A surface potential meter (model 344, manufactured by TRECJAPAN) was provided so that the surface potential of the photoconductor in the image forming process could be measured, and the electrical characteristics and image quality of each photoconductor were evaluated. Note that a laser beam having a wavelength of 780 nm was used as the light source.

  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 in the black background during exposure was measured in order to see 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.

The measurement result of the surface potential was evaluated according to the following criteria.
VG: The initial VL is −100V or more, and the fluctuation range ΔVL after 100k actual shooting is 20V or less.
G: Initial VL is −100V or more, and fluctuation width ΔVL after 100k actual shooting is larger than 20V and 40V or less.
NB: The initial VL is −100V or more, and the fluctuation range ΔVL after 100k actual shooting is larger than 40V and 70V or less.
B: The initial VL is less than −100, or the fluctuation range ΔVL after 100k actual shooting is greater than 70V.

3. Image Evaluation After taking 100k of the photoconductor, print 10 plain images, and the periodicity of black spots per hard copy A3 plate matches the cycle of the photoconductor, and the visible diameter is 0. The number of black spots of 4 mm or more was measured, and the result was judged according to the following criteria.
VG: All hard copies have a good image defect occurrence frequency of 3 / sheet or less.
G: The frequency of occurrence of image defects in all hard copies is 4 to 7 / sheet, but there is no practical problem.
NB: The frequency of occurrence of image defects in all hard copies is 8 to 10 / sheet, but at a practical level.
B: There is one or more hard copies having an image defect occurrence frequency of 11 / sheet or more, which is problematic in practical use.

4). 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. Evaluated in terms of quantity.
VG: Very good improvement level (film slippage is less than 0.5μm / 100k rotation)
G: Improvement level is good (slip amount is 0.5 or more and less than 0.8μm / 100k rotation)
NB: Improvement is seen (film slippage is 0.8 or more and less than 1.0μm / 100k times)
B: No improvement is seen (film slippage is 1.0 μm or more)

5. Coating liquid dispersion stability evaluation For Examples 1 to 6 and Comparative Examples 2 to 5, the dispersion stability (dispersion stability) of the tetrafluoroethylene resin particles in the coating liquid for the charge transport layer used was Evaluation was performed using a laser diffraction particle size distribution measuring apparatus (Microtrac MT-3000II, manufactured by Nikkiso Co., Ltd.).
Specifically, after the dispersion of each coating solution, 40 ml is immediately transferred into a sample tube (50 ml), and the aggregated particle diameter (median diameter) of the aggregated particles after standing still in a constant temperature storage (20 ° C.) for 3 months. D50) was measured.

Then, the dispersion stability was evaluated as follows using the aggregated particle size (particle size after stirring) measured here.
VG: very good (aggregated particle size <0.8 μm).
G: Good (0.8 ≦ aggregated particle diameter <1.5 μm).
NB: At a practically usable level (1.5 ≦ aggregated particle size <4.0 μm).
B: Actual use is not possible (4.0 μm ≦ aggregated particle diameter).

6). Comprehensive evaluation The above items "2" to "4" were comprehensively evaluated and classified as follows.
VG: Even if each item is bad, it is G, and it is very good without any problem in actual use.
G: Even if the item is bad, it is NB, and there is no problem in actual use.
NB: There are two or more NBs, but there is no B and can be used.
B: There are B of more than 1 item, and it is difficult to actually use.

From the above results, all of the photoreceptors obtained in Examples 1 to 6 are superior in electrical characteristics and comprehensive judgment than the photoreceptors obtained in Comparative Examples 1 to 5, It was found that the characteristics were stable and the surface of the photoconductor was also excellent in abrasion.
That is, the photoconductors obtained in Examples 1 to 6 in which the integrated intensity ratio of the high boiling point solvents with respect to BHT in the thermal desorption chromatography is in the range of 10 to 70% is a transition of stable electrical characteristics in the evaluation test. showed that. Among them, Example 2 in which the integrated intensity ratio with respect to BHT is 40% or less, and Example 3 in which the integrated intensity ratio is 20% or less showed a more stable transition.

On the other hand, Comparative Examples 2 and 3 in which the sum of the integral strength ratios of the solvents was more than 70% showed a marked deterioration in electrical characteristics. Further, Comparative Examples 4 and 5 in which the total integrated strength of the solvent was less than 10% in terms of BHT ratio caused thermal deterioration of the components due to the influence of the high drying temperature, and already deteriorated the electrical characteristics in the initial stage.
Further, paying attention to the dispersion stability as the coating liquid, it was confirmed that the dispersed particles can maintain a relatively stable small particle size depending on the amount of the high boiling point solvent added.

  The outermost surface layer of the electrophotographic photoreceptor according to the present invention contains the residual amount of the high boiling point solvent derived from the dispersant containing the specific fine particles and the high boiling point solvent and containing the specific polymer in a specific range, thereby providing abrasion resistance. It is possible to provide an electrophotographic photosensitive member that is high in electrical stability over a long period of time and an image forming apparatus including the photosensitive member.

DESCRIPTION OF SYMBOLS 1 Electrophotographic photoreceptor 11 Conductive 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 34 Imaging lens 35 Mirror 36 Corona charger 37 Developing device 38 Transfer paper cassette 39 Paper feed roller 40 Registration roller 41 Transfer charger 42 Separation charger 43 Conveyor belt 44 Fixing device 45 Paper discharge tray 46 Cleaner 47 Arrow 48 Transfer paper 49 Exposure means 50 Static eliminator

Claims (7)

A laminated photosensitive layer in which a charge generation layer containing at least a charge generation material and a charge transport layer containing a charge transport material are laminated in this order on a conductive substrate, or a charge generation material and a charge transport material on a conductive substrate. An electrophotographic photosensitive member in which a single-layer type photosensitive layer is laminated,
The outermost surface layer of the electrophotographic photosensitive member contains at least polytetrafluoroethylene ethylene particles, and the outermost surface layer of the outermost surface layer is compared with the integrated intensity by analysis of the residual solvent amount using thermal desorption gas chromatography. High boiling point having a boiling point of 100-160 ° C. used as a secondary solvent with respect to the integrated strength of tetrahydrofuran-containing 2,6-di-tert-butyl-4-methylphenol used as a main solvent in the coating liquid to form An electrophotographic photosensitive member comprising 10 to 70% of an integrated intensity ratio combined with a solvent.   2. The electrophotographic photosensitive member according to claim 1, wherein the analysis of the residual solvent amount by the thermal desorption gas chromatography is an analysis based on an integrated intensity comparison of the residual solvent amount at a thermal desorption temperature of 200 ° C. or less.   3. The electrophotographic photosensitive member according to claim 1, wherein, in the analysis of the residual solvent amount by the thermal desorption gas chromatography, the outermost surface layer includes an integrated intensity ratio of 10 to 40% including a high boiling point solvent.   In the analysis of the residual solvent amount by the said thermal desorption gas chromatography, the said outermost surface layer contains the integrated intensity ratio 10-20% which match | combined the high boiling point solvent, The electrophotography as described in any one of Claims 1-3 Photoconductor.   The high boiling point according to any one of claims 1 to 4, comprising a charge transport material, a binder resin, polytetrafluoroethylene particles, a dispersant, and a 0 to 45 wt% toluene-containing tetrahydrofuran solution. A charge transport layer coating solution for producing an electrophotographic photoreceptor containing a solvent.   5. The charge transport layer coating solution comprising a charge transport material, a binder resin, polytetrafluoroethylene particles, a dispersant, and a 0 to 45 wt% toluene-containing tetrahydrofuran solution, wherein the charge transport layer coating solution is used. A method for producing an electrophotographic photosensitive member containing the high boiling point solvent according to any one of the above.   An electrophotographic photosensitive member according to any one of claims 1 to 4, a charging means for charging the electrophotographic photosensitive member, and an electrostatic latent image is formed by exposing the charged electrophotographic photosensitive member. Exposure means for developing, developing means for developing the electrostatic latent image with toner to form a toner image, transfer means for transferring the toner image onto a recording material, and the transferred toner image on the recording material An image forming apparatus comprising fixing means for fixing to an image.

Images