JP2006084578A - Method for producing electrophotographic photoreceptor, electrophotographic photoreceptor, and image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing an electrophotographic photoreceptor in a process where a coating material composition for an electrophotographic photoreceptor is discharged from a discharge nozzle, so as to be applied, the composition can be stably discharged without generating the clogging of the discharge nozzle caused by drying, flocculation or the like, and can be applied to the surface of an electrically conductive substrate at a uniform thickness, to provide an electrophotographic photoreceptor produced by the production method, and to provide an image forming device using the electrophotographic photoreceptor. <P>SOLUTION: In the method for producing an electrophotographic photoreceptor where a coating material composition for an electrophotographic photoreceptor is discharged as droplets, so as to form an electric charge generation layer, the coating material composition for an electrophotographic photoreceptor comprises an electric charge generation substance, a binding resin and a solvent, the solvent comprises one or more kinds of high boiling point solvents having a boiling point of 120 to 260°C, the high boiling point solvent is comprised by 5 to 40 pts.wt. in 100 pts.wt. of the coating material composition for an electrophotographic photoreceptor, the volume of the droplets is 10 to 100 pl, and the electric charge generation layer is formed in such a manner that its film thickness reaches 0.01 to 1μm. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for producing an electrophotographic photosensitive member for forming a charge generation layer constituting an electrophotographic photosensitive member, an electrophotographic photosensitive member produced by the production method, and an image forming apparatus using the electrophotographic photosensitive member.

  Conventionally, an inorganic photoconductive material such as a selenium alloy, zinc oxide and cadmium sulfide has been used for an electrophotographic photoreceptor used in an electrophotographic apparatus to which the Carlson process is applied. Inorganic photoconductive materials are disadvantageous in that they are harmful to the human body, have poor film-forming properties, are heavy, and are expensive. Recently, organic photoconductive materials are less toxic than inorganic photoconductive materials, have superior film-forming properties and light weight, and are inexpensive. Development of electrophotographic photoreceptors using photoconductive materials has been actively conducted.

  As a general organic photoconductive material, for example, a bisazo compound can be exemplified. However, this type of organic photoconductive material exhibits good sensitivity to light in the short wavelength region or medium wavelength region, but has low sensitivity to light in the long wavelength region. For this reason, in the case of an electrophotographic apparatus using a semiconductor laser as a light source, practical application is difficult. In addition, methine squarylate dyes, indoline dyes, cyanine dyes and pyrylium dyes are known as organic photoconductive materials having relatively good sensitivity to light in the long wavelength range. Since it is subjected to stability against repeated use, it is difficult to put it to practical use. Accordingly, phthalocyanine compounds are known as organic photoconductive materials that have good sensitivity to light in the long wavelength region and relatively good stability to repeated use. In recent years, phthalocyanine compounds have been actively studied as organic photoconductive materials, and are widely used as charge generating materials in general digital electrophotographic apparatuses using laser exposure. Among them, it is known that titanyl phthalocyanine compounds such as oxo titanyl phthalocyanine are highly sensitive to light in a long wavelength region, and thus the charge generation layer can be made thin. In addition, since titanyl phthalocyanine compounds are very expensive, charge generation layers using titanyl phthalocyanine compounds are often used as thin films having a thickness of 1 μm or less.

  An organic electrophotographic photosensitive member using an organic photoconductive material is separated into a charge generation layer that receives light and generates charge carriers and a charge transport layer that transports the generated charge carriers. A so-called function-separated laminated type electrophotographic photosensitive member is known. Such a function-separated layered organic electrophotographic photosensitive member can be formed by using an optimum material for exhibiting its function in each layer, and by combining these layers, the sensitivity is greatly increased. The sensitivity of the wavelength can be increased according to the wavelength of light for exposure. Because of these advantages, the functionally separated laminated electrophotographic photosensitive member has become the mainstream of development and is being put to practical use and is used in electrophotographic apparatuses such as copying machines, printers and facsimile machines. ing.

  The function-separated stacked organic electrophotographic photoreceptor has a photosensitive layer including a charge generation layer and a charge transport layer. The photosensitive layer is generated by applying a coating composition for an electrophotographic photosensitive member in which an organic charge generating material and a binder resin are dispersed or dissolved in an organic solvent on a hollow cylindrical conductive substrate and drying it. It is manufactured by forming a charge transporting layer by applying a coating composition for an electrophotographic photoreceptor in which a charge transporting substance and a binder resin are dispersed or dissolved in an organic solvent and drying the layer. Is done. The photosensitive layer is required to have a uniform thickness. In particular, the charge generation layer using a titanyl phthalocyanine compound is required to be a thin layer. In other words, by applying the photosensitive layer with a thinner and uniform thickness, it is possible to achieve higher functionality of the electrophotographic photosensitive member, and a new coating method that can be applied at a lower cost. Development is under consideration.

  As a method for forming a photosensitive layer by applying a coating composition for an electrophotographic photosensitive member on a conductive substrate which is a photosensitive element tube, a dip coating method, a roll coating method, a blade coating method, a spray method, and the like have been conventionally used. Are known. However, there is a problem that a uniform coating film cannot be obtained and production efficiency is poor.

  In the dip coating method, one end of a conductive substrate that is a photosensitive element tube is held, and the surface on which the coating composition for the electrophotographic photosensitive member is applied is held perpendicular to the liquid surface of the coating composition for the electrophotographic photosensitive member. This is a method of immersing in a coating composition for an electrophotographic photoreceptor as it is, and then pulling it up from the coating composition for an electrophotographic photoreceptor, and is often used in the production of a photoreceptor. However, the film thickness of the layer obtained by the dip coating method depends on the speed at which the conductive substrate is pulled up from the electrophotographic photoreceptor coating composition, the viscosity of the electrophotographic photoreceptor coating composition, and the electrophotographic photoreceptor coating composition. Since it largely depends on the evaporation rate of the volatile components contained, these must be strictly controlled. Also, since the conductive substrate is pulled up and down from the electrophotographic photosensitive member coating composition, the coating composition for the electrophotographic photosensitive member hangs down on the conductive substrate due to the action of gravity, and the conductive substrate is pulled in the lifting direction. The lower film thickness becomes thicker than the upper film thickness, resulting in a difference in sensitivity between the upper and lower sides. The coating composition for the electrophotographic photosensitive member applied to the lower part is difficult to dry. If another coating composition for the electrophotographic photosensitive member is applied before it is completely dried, the coating composition for the electrophotographic photosensitive member is In some cases, the desired photosensitive layer may not be formed. Furthermore, there is a problem in that the coating composition for an electrophotographic photosensitive member wraps around an end portion that becomes a non-printing portion, and a masking and a coating composition removing step for the electrophotographic photosensitive member are required. In addition, since the conductive substrate is immersed, a minimum electrophotographic photoreceptor coating composition capable of immersing the conductive substrate is necessary, and the time for which the electrophotographic photoreceptor coating composition can be used. When (pot life) is passed, the electrophotographic photoreceptor coating composition must be discarded, and there is a problem that the use efficiency of the electrophotographic photoreceptor coating composition is poor.

  The roll coating method forms a film of a coating composition for an electrophotographic photosensitive member with a regulated film thickness on an application roll, and rotates a conductive substrate and an application roll arranged so as to be close to or in contact with the application roll, respectively. In this method, the coating composition is applied by transferring the coating composition for an electrophotographic photoreceptor from a coating roll onto a conductive substrate. However, after the coating, when the coating roll and the conductive substrate are separated from each other, a phenomenon in which excess coating composition for the electrophotographic photosensitive member adheres to the conductive substrate due to the surface tension of the coating composition for the electrophotographic photosensitive member, so-called There is a problem that a liquid drawing phenomenon is likely to occur, and a seam remains in the coating film due to the liquid drawing phenomenon, resulting in a non-uniform film thickness, resulting in image defects.

  In the blade coating method, a blade is disposed at a position close to the conductive substrate, the electrophotographic photoreceptor coating composition is supplied to the blade, and the electrophotographic photoreceptor coating composition is applied to the conductive substrate by the blade, This is a coating method in which the blade is retracted after one turn of the conductive substrate. In this method, high productivity can be obtained, but when the blade is retracted, a part of the coating film applied to the conductive substrate rises due to the surface tension of the coating composition for the electrophotographic photoreceptor, and the film thickness is increased. There is a problem of non-uniformity.

  In the spray method, the coating composition for an electrophotographic photosensitive member is ejected as fine particles from a spray nozzle and applied, so the appearance after coating is good, but the thickness of the layer formed by a single coating is thin Therefore, in order to obtain a desired film thickness, the application must be repeated a plurality of times. Further, when a large amount of the coating composition for an electrophotographic photosensitive member is applied at once, there is a problem that the coating composition for an electrophotographic photosensitive member drips and a coating layer having a non-uniform thickness is formed. Further, since the spray nozzle discharges in a cone shape, the coating accuracy is poor, and masking is necessary to prevent the coating composition for the electrophotographic photosensitive member from being wrapped around the end of the conductive substrate. In addition, the coating efficiency is poor, and an apparatus for collecting the uncoated electrophotographic photoreceptor coating composition is required. In order to reuse the collected electrophotographic photoreceptor coating composition, a processing apparatus is newly added. It becomes necessary, and processes other than coating increase, resulting in poor production efficiency.

  As a method other than the above, there is a method of applying a coating composition for an electrophotographic photoreceptor by an ink jet method. The method of applying a coating composition for an electrophotographic photosensitive member by an inkjet method is a method in which a coating composition for an electrophotographic photosensitive member is applied from a minute nozzle that is a discharge nozzle while moving an object to be coated and the discharge nozzle relatively. It is a method of ejecting as droplets and adhering to an object to be coated. Further, in the method of discharging droplets of the electrophotographic photosensitive member coating composition from the discharge nozzle, the electrophotographic photosensitive member coating composition is extruded by the vibration of the piezoelectric element (piezo element) and discharged as droplets. Piezo method, voltage applied to heater, bubble jet (registered trademark) method that generates bubbles in electrophotographic photosensitive member coating composition and ejects droplets of electrophotographic photosensitive member coating composition, and voltage is applied to heater There is a thermal ink jet method in which bubbles are generated in the coating composition for an electrophotographic photosensitive member, and the bubbles are ruptured to discharge droplets of the coating composition for the electrophotographic photosensitive member.

  A typical prior art is described in US Pat. The application method of the coating liquid (coating composition for electrophotographic photoreceptors) of Patent Document 1 is a method of applying the coating liquid by an ink jet method.

  As another conventional technique, a technique similar to the technique of Patent Document 1 is described in Patent Document 2. The method for producing an electrophotographic photosensitive member of Patent Document 2 is a method in which a coating material for forming an electrophotographic photosensitive member is continuously applied onto a streak from a plurality of minute openings by applying pressure.

Japanese Patent Laid-Open No. 11-19554 Japanese Patent No. 2644582

  In the ink jet system, the charge generation layer is formed by discharging the electrophotographic photoreceptor coating composition in droplets from a small discharge nozzle of several tens of μm. Therefore, it is important that the coating composition for an electrophotographic photosensitive member can be stably ejected without causing clogging due to drying and aggregation of the pigment, and further, the ejected liquid droplets may flow. Therefore, it is required that the formed charge generation layer has good uniformity in surface condition and film thickness.

  In general, the smaller the droplets ejected, the easier it is to ensure uniformity. However, since the surface area increases with respect to the volume, it becomes easy to dry. That is, clogging is likely to occur at the discharge nozzle, resulting in poor discharge performance. Also, the larger the droplets that are ejected, the easier it is to ensure the ejection properties, but the ejected droplets will drip, making it difficult to ensure uniformity.

  According to the coating liquid application method disclosed in Patent Document 1, since the coating liquid is applied by an ink jet method, the coating liquid can fly linearly and with very high accuracy as a droplet. Each discharge nozzle can be controlled. Therefore, since the coating liquid can be applied to a place where the coating liquid needs to be applied, it is not necessary to perform masking and the coating efficiency is very high. In addition, the coating liquid can be easily replaced simply by replacing the tank for storing the coating liquid, and the coating liquid can be used up and the production efficiency is very high. However, since the coating liquid uses a low-boiling point solvent such as tetrahydrofuran as the solvent, the coating liquid is rapidly volatilized and dries at the discharge nozzle, and the discharge nozzle becomes clogged.

  Unlike the case of using titanyl phthalocyanine compound, which is a very expensive charge generation material, an azo pigment is used as the charge generation material. The uniformity can be maintained by discharging a large amount of the coating liquid.

  The charge generation layer can be thinned by reducing the droplet size of the coating liquid. However, when the droplet is small, it becomes easy to dry, and the droplet is dried before the charge generation layer having a uniform surface state and film thickness is formed by the flow of the discharged droplet. End up. That is, it is difficult to form a thin charge generation layer while maintaining uniformity.

  According to the method for producing an electrophotographic photoreceptor disclosed in Patent Document 2, since a coating for forming an electrophotographic photoreceptor is applied from a plurality of micro openings by applying pressure, unlike the application method using an ink jet method, a wide range is provided. Can be applied. However, in this method, each minute opening cannot be controlled independently, and since a tube is connected between the pump that applies pressure and the minute opening, a time difference occurs between pressurization and discharge, Both accuracy and response are degraded.

  An object of the present invention is to discharge a coating composition for an electrophotographic photosensitive member from a discharge nozzle and apply it on a conductive substrate without causing clogging of the discharge nozzle due to drying and aggregation. It is an object to provide a method for producing an electrophotographic photosensitive member that can be applied with a uniform thickness, an electrophotographic photosensitive member produced by the production method, and an image forming apparatus using the electrophotographic photosensitive member.

The present invention is a method for producing an electrophotographic photoreceptor, in which a charge generation layer is formed by discharging a coating composition for an electrophotographic photoreceptor as droplets,
The electrophotographic photoreceptor coating composition includes a charge generating material, a binder resin, and a solvent,
The solvent includes one or more high-boiling solvents having a boiling point of 120 ° C. or higher and 260 ° C. or lower,
The high boiling point solvent contains 5 parts by weight or more and 40 parts by weight or less in 100 parts by weight of the coating composition for an electrophotographic photosensitive member,
The volume of the droplet is 10 pl or more and 100 pl or less,
An electrophotographic photoreceptor manufacturing method is characterized in that the charge generation layer is formed so that the film thickness d of the charge generation layer is 0.01 μm <d <1 μm.

  According to the present invention, the charge generating substance is a titanyl phthalocyanine compound.

  In the present invention, the high-boiling solvent is one or more high-boiling solvents selected from cyclohexanone, pyrrolidone, n-methylpyrrolidone and p-xylene.

  Further, the invention is characterized in that the solvent includes a low boiling point solvent having a boiling point of 30 ° C. or higher and lower than 120 ° C.

  In the present invention, the low-boiling point solvent has a boiling point difference of 70 ° C. or more with respect to the high-boiling point solvent.

Further, the present invention is an electrophotographic photosensitive member produced by the above-described method for producing an electrophotographic photosensitive member.
The present invention also provides an image forming apparatus using the electrophotographic photosensitive member.

  According to the present invention, a coating composition for an electrophotographic photoreceptor containing a charge generating material, a binder resin and a solvent is ejected as droplets having a volume of 10 pl to 100 pl. By doing so, the amount of liquid droplets to be ejected is preferable, and the amount can be strictly controlled, so that a thin charge generation layer with high uniformity in film thickness and surface state can be formed. Furthermore, since it does not take much time to form the charge generation layer having a desired film thickness, the coating efficiency is high.

  The coating composition for an electrophotographic photoreceptor contains one or more high-boiling solvents having a boiling point of 120 ° C. or more and 260 ° C. or less as a solvent, and the high-boiling solvent is used for an electrophotographic photoreceptor. 5 parts by weight or more and 40 parts by weight or less are included in 100 parts by weight of the coating composition. By using such a coating composition for an electrophotographic photosensitive member, drying and aggregation due to volatilization of the solvent of the coating composition for an electrophotographic photosensitive member are less likely to occur, and clogging of the discharge nozzle is less likely to occur. . Furthermore, since the high boiling point solvent can enhance the effect of making the film thickness and surface state of the charge generation layer uniform, a charge generation layer having a more uniform film thickness and surface state can be formed.

  Further, the charge generation layer is formed so that the film thickness d of the charge generation layer satisfies 0.01 μm <d <1 μm. By doing so, it is possible to reduce the amount of expensive charge generation material used while having sufficient performance as a charge generation layer, which is excellent in terms of cost.

  According to the present invention, since the charge generation material is a titanyl phthalocyanine compound, a charge generation layer with better sensitivity to light in a long wavelength region can be formed.

  According to the invention, the high boiling point solvent is one or more high boiling point solvents selected from cyclohexanone, pyrrolidone, n-methylpyrrolidone and p-xylene. By doing so, the volatility of the electrophotographic photoreceptor coating composition becomes appropriate and can be discharged more stably, so that a charge generation layer with higher uniformity can be formed.

  Further, according to the present invention, since the solvent contains a low boiling point solvent having a boiling point of 30 ° C. or higher and lower than 120 ° C., the discharged electrophotographic photosensitive member coating composition is appropriately dried and is uniform. A higher charge generation layer can be formed.

  According to the present invention, since the low boiling point solvent has a boiling point of 70 ° C. or more lower than that of the high boiling point solvent, the electrophotographic photosensitive member coating composition is prevented from drying at the time of discharge, and the electrophotographic photosensitive member coating composition after coating is applied. Thus, a more uniform charge generation layer can be formed.

  According to the present invention, since the electrophotographic photosensitive member is produced by the above-described method for producing an electrophotographic photosensitive member, the electrophotographic photosensitive member has a charge generation layer, and the charge generation layer has an appropriate thickness. The charge generation layer has high uniformity such as the film thickness and surface state of the charge generation layer.

  Further, according to the present invention, since the image forming apparatus uses the above-described electrophotographic photosensitive member, it is possible to obtain an image having excellent image quality without blurring or fogging.

[Method for producing electrophotographic photosensitive member]
As a first embodiment of the present invention, a method for producing an electrophotographic photoreceptor will be described.

  The method for producing an electrophotographic photosensitive member includes an undercoat layer forming step, a charge generation layer forming step, and a charge transport layer forming step. Each step will be described.

(Undercoat layer forming process)
First, a coating composition for an electrophotographic photosensitive member for an undercoat layer is prepared by dispersing an oxide, a binder resin, a solvent, and the like with a disperser.

  As the oxide, a known oxide can be used, and examples thereof include titanium oxide, tin oxide, and aluminum oxide. As the binder resin, known resins can be used, and examples thereof include polyamide, polyurethane, cellulose, nitrocellulose, polyvinyl alcohol, polyvinyl pyrrolidone, polyacrylamide, gelatin, starch, casein, and N-methoxymethylated nylon. it can. As the solvent, a known solvent can be used, and examples thereof include methyl alcohol and 1,2-dichloroethane. A known disperser can be used as the disperser, and examples thereof include a paint shaker.

  Next, an undercoat layer is formed by applying the prepared coating composition for an electrophotographic photosensitive member to a photosensitive element tube which is a conductive substrate by a dip coating method.

The conductive substrate serves as an electrode for the photoreceptor and also serves as a support for other layers. The shape may be any of a cylindrical shape, a plate shape, a film shape, and a belt shape. The material may be any conductive material, such as aluminum, stainless steel, copper and nickel, and a polyester film provided with a conductive layer such as aluminum, copper, palladium, tin oxide and indium oxide on the surface. Insulating materials such as phenolic resin pipes and paper tubes. Those having a volume resistance of 10 ¹⁰ Ω · cm or less are preferred, and the surface may be oxidized to adjust the volume resistance.

(Charge generation layer forming process)
First, a charge generating material, a binder resin, an additive, and the like are added to a solvent and then dispersed by a disperser to prepare an electrophotographic photosensitive member coating composition for a charge generating layer. A coating composition for an electrophotographic photosensitive member for a charge generation layer includes a charge generation substance, a binder resin, a solvent, and the like, and forms a charge generation layer by discharging the droplet from a discharge nozzle. be able to. The charge generation substance and the binder resin are materials for forming the charge generation layer, and need to exhibit a function as the charge generation layer. Further, the discharge property, volatility, leveling property after coating, and the like of the coating composition for an electrophotographic photosensitive member are adjusted by a solvent.

  As the disperser, known ones can be used, and examples thereof include a ball mill, a sand grinder, a paint shaker, and an ultrasonic disperser.

  As the charge generation material, a known charge generation material can be used as long as it absorbs visible light and generates a charge, and examples thereof include inorganic pigments, organic pigments, and organic dyes. Examples of inorganic pigments include selenium, selenium alloys, arsenic-selenium, cadmium sulfide, zinc oxide, and amorphous silicon. Examples of organic pigments include phthalocyanine compounds, azo compounds, quinacridone compounds, polycyclic quinone compounds, and perylene compounds. Examples of organic dyes include thiapyrylium salts and squarylium salts. Among these, phthalocyanine compounds are preferable, and titanyl phthalocyanine compounds such as oxotitanyl phthalocyanine compounds are more preferably used. Since the titanyl phthalocyanine compound has very good sensitivity to light in a long wavelength region, even if the charge generation layer is a thin film, the function as the charge generation layer can be sufficiently exhibited.

  As the binder resin, known resins can be used, and examples thereof include polyarylate, polyvinyl butyral, polycarbonate, polyester, polystyrene, polyvinyl chloride, phenoxy resin, epoxy resin, silicone, and polyacrylate.

  The solvent includes a high boiling point solvent and a low boiling point solvent. By including the high boiling point solvent and the low boiling point solvent, the volatility of the coating composition for an electrophotographic photosensitive member can be adjusted, and further, since the high boiling point solvent is included, the leveling property after coating can be enhanced.

  The boiling point of the high boiling point solvent is preferably 120 ° C. or higher and 260 ° C. or lower, and more preferably 150 ° C. or higher and 260 ° C. or lower. A known solvent can be used as the high boiling point solvent. For example, cyclohexanone, pyrrolidone, n-methylpyrrolidone and p-xylene can be mentioned, and cyclohexanone, pyrrolidone and n-methylpyrrolidone are more preferable. Two or more high boiling solvents may also be included. The content of the high boiling point solvent in the present invention is 5 parts by weight or more and 40 parts by weight or less with respect to 100 parts by weight of the electrophotographic coating composition. When the amount is less than 5 parts by weight, the discharge property from the discharge nozzle and the leveling property after coating are deteriorated. When the amount is more than 40 parts by weight, the coating composition for electrophotographic photoreceptors after coating becomes difficult to dry. The film thickness of the charge generation layer cannot be made uniform. On the other hand, when the boiling point of the high-boiling solvent exceeds 260 ° C., the solvent is not dried and the film thickness of the charge generation layer cannot be made uniform.

  The boiling point of the low boiling point solvent is preferably 30 ° C or higher and lower than 120 ° C. Further, the low boiling point solvent preferably has a difference in boiling point from the high boiling point solvent of 70 ° C. or higher, more preferably 80 ° C. or higher. By doing so, it is possible to balance the prevention of drying of the coating composition for electrophotographic photosensitive member at the time of ejection and the drying of the coating composition for electrophotographic photosensitive member after application. As the low boiling point solvent, known solvents can be used, and examples thereof include isopropyl alcohol, toluene, acetone, ethyl methyl ketone, ethyl cellosolve, ethyl acetate, methyl acetate, dichloromethane, dichloroethane, chlorobenzene, and ethylene glycol dimethyl ether. .

  The electrophotographic photoreceptor coating composition for the charge generation layer may comprise an additive such as a chemical sensitizer, an optical sensitizer, a plasticizer, a leveling agent, an antioxidant, and an ultraviolet absorber. .

  Chemical sensitizers or optical sensitizers may be included to improve sensitivity and to prevent increased residual potential and layer fatigue after repeated use. Known electron accepting materials can be used as chemical sensitizers, including acid anhydrides such as succinic anhydride, maleic anhydride, phthalic anhydride and 4-chloronaphthalic anhydride, tetracyanoethylene, terephthalmalondinitrile. And cyano compounds such as 7,7,8,8-tetracyanoquinodimethane, aldehydes such as 4-nitrobenzaldehyde, quinones such as anthraquinone, 1-nitroanthraquinone and p-benzoquinone, 2,4,7-tri And polycyclic or heterocyclic nitro compounds such as nitrofluorenone and 2,4,5,7-tetranitrofluorenone. As the optical sensitizer, known dyes can be used, and examples thereof include xanthene dyes, thiazine dyes, triphenylmethane dyes, quinoline pigments, and copper phthalocyanine.

  A plasticizer may be included in order to improve the moldability, flexibility and mechanical strength of the formed layer. Known plasticizers can be used, and examples thereof include dibasic acid esters, fatty acid esters, phosphate esters, phthalate esters, chlorinated paraffins, and epoxy type plasticizers.

  A leveling agent may be included in order to prevent the skin of the layer to be formed. As a leveling agent, a well-known thing can be used and polysiloxane etc. are mentioned.

  In order to improve the durability of the formed layer, an antioxidant and a UV absorber may be included. As the antioxidant, known compounds can be used, and examples thereof include phenolic compounds, hydroquinone compounds, tocopherol compounds, and amine compounds. A well-known thing can be used as a ultraviolet absorber.

  The above-described coating composition for an electrophotographic photosensitive member for a charge generation layer is discharged as a droplet from a discharge nozzle onto a photosensitive element tube on which an undercoat layer is formed, applied, dried, and solidified to obtain a charge. A generation layer is formed. In that case, the volume of the droplet is preferably 10 pl or more and 100 pl or less, and more preferably 30 pl or more and 80 pl or less. If the volume of the droplet is smaller than 10 pl, it is difficult to control the droplet with high accuracy, and it takes too much time to secure a desired film thickness, resulting in low coating efficiency. In addition, if the volume of the droplet is larger than 100 pl, the amount of the droplet discharged at one time becomes too large, the surface of the formed charge generation layer becomes rough, and a highly uniform charge generation layer is formed. Cannot be formed. The charge generation layer is preferably formed so that the film thickness d of the charge generation layer is 0.01 μm <d <1 μm. More preferably, the charge generation layer is formed to satisfy 0.1 μm <d <0.8 μm. In order to reduce the film thickness d to 0.01 μm or less, it is necessary to discharge very small droplets with high accuracy, and it is also necessary to use a coating composition for an electrophotographic photosensitive member in which a charge generating substance is further dispersed. In addition, when the film thickness d is set to 1 μm or more, the discharged coating composition for an electrophotographic photosensitive member becomes difficult to dry and drips, so that the film is biased and a charge generation layer having high leveling properties is formed. Cannot be formed. There is a coating method using an ink jet method as a method of discharging a coating composition for an electrophotographic photosensitive member as droplets having a volume of 10 pl to 100 pl from a discharge nozzle onto a photosensitive element tube having an undercoat layer formed thereon. . FIG. 1 is a schematic view showing an ink jet coating apparatus used in the present invention. In the coating method using the inkjet method, droplets of the coating composition for an electrophotographic photosensitive member are ejected using the inkjet coating apparatus shown in FIG. The conductive substrate 1 is held horizontally by the rotating shaft 2 and can be rotated at a predetermined speed. The discharge part 4 can be moved in parallel with the rotating shaft 2 while keeping a certain distance from the conductive substrate 1 by the guide rail 3. The electrophotographic photoreceptor coating composition is supplied from the storage tank 6 through the conveyance path 5. A piezoelectric element is installed in the discharge unit 4. A voltage is applied to the discharge unit 4, and the volume in the discharge unit 4 is changed by expansion and contraction of the piezoelectric element to discharge the electrophotographic photosensitive member coating composition droplet 7. be able to. By doing so, it is possible to form a charge generation layer that is thin and has a high leveling property that is uniform in film thickness, surface condition, and the like.

(Charge transport layer forming step)
First, a coating composition for an electrophotographic photoreceptor for a charge transport layer is prepared by dispersing a charge transport material, a binder resin, a solvent, and the like with a disperser.

As the charge transport material, a known charge transport material can be used, and examples thereof include hydrazone compounds such as 4-dibenzylamino-2-methylbenzaldehyde-1,1-diphenylhydrazone. The binder resin only needs to be compatible with the charge transport material, for example, polycarbonate, copolymer polycarbonate, polyarylate, polyvinyl butyral, polyamide, polyester, epoxy resin, polyurethane, polyketone, polyvinyl ketone, polystyrene, polyacrylamide, phenol. Examples thereof include resins, phenoxy resins and polystyrene resins, and copolymer resins thereof. You may use these resin individually or in mixture of 2 or more types. Among them, polystyrene, polycarbonate, copolymer polycarbonate, polyarylate and polyester resin are preferable because they have a volume resistance of 10 ¹³ Ω or more and are excellent in film formability and potential characteristics. As the solvent, known solvents can be used, such as alcohols such as methanol and ethanol, ketones such as acetone, ethyl methyl ketone and cyclo, ethers such as ethyl ether, tetrahydrofuran, dioxane and dioxolane, chloroform, dichloromethane and Aliphatic halogenated hydrocarbons such as dichloroethane, aromatics such as benzene, chlorobenzene and toluene. Note that the charge transport layer is very thick, such as 10 μm or more and 50 μm or less, and it is necessary to repeatedly apply the ink by an inkjet method. Therefore, a method such as dip coating or spray coating may be used. Furthermore, an additive similar to the coating composition for an electrophotographic photosensitive member for the charge generation layer may be included.

  Next, a charge transport layer is formed by applying the prepared coating composition for an electrophotographic photoreceptor to the photoreceptor element tube on which the charge generation layer is formed by a dip coating method.

[Electrophotographic photoreceptor]
An electrophotographic photoreceptor will be described as a second embodiment of the present invention.

  FIG. 2 is a schematic cross-sectional view showing an electrophotographic photosensitive member 10 according to an embodiment of the present invention. The electrophotographic photosensitive member 10 is an electrophotographic photosensitive member manufactured by the above-described method for manufacturing an electrophotographic photosensitive member, and an undercoat layer 15 is provided on a conductive substrate 11, and a photosensitive layer 14 is further formed thereon. It has a provided structure. Further, since the photosensitive layer 14 is formed by laminating the charge generation layer 12 mainly containing the charge generation material and the charge transport layer 13 mainly containing the charge transport material, the electrophotographic photosensitive member 10 has the function separation. It is a laminated photoreceptor. When the surface of the photoreceptor provided with such a photosensitive layer 14 is negatively charged with a charger or the like and irradiated with light having a wavelength that is absorbed by the charge generation layer 12, electrons and holes are charged in the charge generation layer 12. appear. The holes are transferred to the surface of the photoreceptor by the charge transport material contained in the charge transport layer 13 to neutralize the negative charge on the surface, and the electrons in the charge generation layer 12 are the conductive support in which a positive charge is induced. The function-separated laminated type photoreceptor functions by moving to the 11 side and neutralizing the positive charge.

  The undercoat layer 15 is a layer formed by the above-described undercoat layer forming step, and serves as an adhesive layer between the conductive substrate 11 and the photosensitive layer 14, and charges flow from the conductive substrate 11 to the photosensitive layer 14. It serves as a barrier layer that suppresses the above. In this way, the undercoat layer 15 maintains the charging characteristics of the photoreceptor, so that the photoreceptor can be maintained for a long time. In order to exhibit the function, the film thickness is preferably 0.1 μm or more and 10 μm or less.

  The charge generation layer 12 is a layer formed by the above-described charge generation layer formation step, and is a layer that generates charges by visible light. The film thickness of the charge generation layer 12 is preferably 0.01 μm or more and 1 μm or less. By doing so, while having sufficient performance as a charge generation layer, the amount of expensive charge generation material used can be reduced, which is excellent in terms of cost.

  The charge transport layer 13 is a layer formed by the above-described charge transport layer forming step, and is a layer that transports the charge generated in the charge generation layer 12 to the surface of the photoreceptor. In order to exhibit the function, the ratio of the charge transport material in the charge transport layer is preferably 30% by weight or more and 80% by weight or less. The film thickness is preferably 10 μm or more and 50 μm or less, and more preferably 15 μm or more and 40 μm or less.

[Image forming apparatus]
An image forming apparatus will be described as a third embodiment of the present invention. The image forming apparatus according to the present invention is not limited to the following description.

  FIG. 3 is a configuration diagram showing a simplified configuration of the image forming apparatus 21 according to the present invention. An image forming apparatus 21 shown in FIG. 3 is mounted with the above-described electrophotographic photosensitive member which is the second embodiment of the present invention. The configuration of the image forming apparatus 21 and the image forming operation will be described below with reference to FIG.

  The image forming apparatus 21 includes an electrophotographic photosensitive member 22, a charger 23, a developing device 24, a transfer charger 25, a cleaner 26, a fixing device 27, and the like. The electrophotographic photosensitive member 22 has a cylindrical shape, and is driven to rotate at a predetermined peripheral speed in the direction of an arrow 31 by a driving unit (not shown). Around the electrophotographic photosensitive member 22, a charger 23, a semiconductor laser (not shown), a developing device 24, a transfer charger 25, and a cleaner 26 are provided in this order along the rotation direction of the electrophotographic photosensitive member 22. . A fixing device 27 is provided in the traveling direction of the recording medium 33.

  An image forming operation by the image forming apparatus 21 will be described. First, the electrophotographic photoreceptor 22 is uniformly charged with a predetermined positive or negative potential on the surface facing the charger 23 by a contact or non-contact charger 23. Next, a laser beam 34 is irradiated from a semiconductor laser (not shown), and the surface of the electrophotographic photosensitive member 22 is exposed. The laser beam 34 is repeatedly scanned in the longitudinal direction of the electrophotographic photosensitive member 22 which is the main scanning direction, and accordingly, electrostatic latent images are sequentially formed on the surface of the electrophotographic photosensitive member 22. The formed electrostatic latent image is developed as a toner image by the developing device 24 provided on the downstream side in the rotation direction from the image forming point of the laser beam 34.

  In synchronism with the exposure to the electrophotographic photosensitive member 22, the recording medium 33 is fed from the direction of the arrow 32 to the transfer charger 25 provided on the downstream side in the rotation direction of the developing device 24.

  The toner image formed on the surface of the electrophotographic photosensitive member 22 in the developing unit 24 is transferred onto the surface of the recording medium 33 by the transfer charger 25. The recording medium 33 to which the toner image has been transferred is conveyed to a fixing device 27 by a conveying belt (not shown), and the fixing device 27 fixes the toner image to the recording medium 33 to form a part of the image.

  The toner remaining on the surface of the electrophotographic photosensitive member 22 is removed by a cleaner 26 provided with a neutralizing lamp (not shown) further downstream in the rotation direction of the transfer charger 25 and upstream in the rotation direction of the charger 23. The By further rotating the electrophotographic photosensitive member 22, the above operation is repeated and an image is formed on the recording medium 33. The recording medium 33 on which the image is formed in this manner is discharged outside the image forming apparatus 21.

  Hereinafter, the present invention will be specifically described with reference to examples and comparative examples, but the present invention is not limited to the examples as long as the gist thereof is not exceeded.

[Example 1]
(Coating composition for electrophotographic photoreceptor for undercoat layer)
4 parts by weight of titanium oxide (TiO ₂ : surface-coated needle-shaped rutile type) and 6 parts by weight of copolymer nylon resin (manufactured by Toray Industries, Inc .: CM8000) as a binder resin, 35 parts by weight of methyl alcohol and 65 parts by weight of 1,2-dichloroethane After being added to a part of the mixed solvent, it was dispersed with a paint shaker for 8 hours to prepare a coating composition for an electrophotographic photoreceptor for an undercoat layer.

(Coating composition for electrophotographic photoreceptor for charge generation layer)
Mixing 1 part by weight of titanyl phthalocyanine pigment and 1 part by weight of polyvinyl butyral resin (manufactured by Denki Kagaku Kogyo Co., Ltd .: # 6000-C) with 83 parts by weight of tetrahydrofuran (boiling point: 66 ° C.) and 15 parts by weight of cyclohexanone (boiling point: 155 ° C.) After adding to the solvent, it was dispersed for 12 hours with a paint shaker to prepare a coating composition for an electrophotographic photoreceptor for a charge generation layer.

(Coating composition for electrophotographic photoreceptor for charge transport layer)
As a hydrazone-based charge transport material, 4-dibenzylamino-2-methylbenzaldehyde-1,1-diphenylhydrazone 9 parts by weight, bisphenol Z type polycarbonate resin (Mitsubishi Gas Chemical Co., Ltd .: Z-400) 14 parts by weight and silicone A coating composition for an electrophotographic photoreceptor for a charge transport layer was prepared by adding 0.02 part by weight of a system leveling agent (manufactured by Shin-Etsu Chemical Co., Ltd .: KF-96) to 76 parts by weight of tetrahydrofuran and mixing. .

(Undercoat layer forming process)
An aluminum non-cutting cylindrical tube formed by an ED method having a diameter of 30 mm and a length of 360 mm was used as a photosensitive element tube which is a conductive substrate. The coating composition for the electrophotographic photoreceptor for the undercoat layer was applied to the above-described photoreceptor element tube by a dip coating method and naturally dried to form an undercoat layer having a thickness of 1.0 μm.

(Charge generation layer forming process)
A coating composition for an electrophotographic photosensitive member for a charge generation layer is formed on a photosensitive element tube rotating at 60 rpm from a discharge nozzle of a remodeling machine (modified to a piezo method) of an inkjet printing apparatus (manufactured by Sharp Corporation: AJ-2000). The charge generation layer having a thickness of 0.2 μm was formed on the undercoat layer by applying the ink by discharging it onto the undercoat layer so that the volume of the droplet was 30 pl, followed by natural drying.

(Charge transport layer forming step)
The electrophotographic photoreceptor coating composition for the charge transport layer is applied by dip coating to the photoreceptor tube provided with the charge generation layer formed as described above, dried at 140 ° C. for 1 hour, A charge transport layer having a thickness of 25 μm was formed to produce a function-separated laminated type photoreceptor.

[Example 2]
In the electrophotographic photoreceptor coating composition for the charge generation layer, the same as Example 1 except that pyrrolidone (boiling point: 245 ° C.) is used instead of cyclohexanone.

[Example 3]
In the coating composition for an electrophotographic photoreceptor for the charge generation layer, the same as Example 1 except that n-methylpyrrolidone (boiling point: 200 ° C.) is used instead of cyclohexanone.

[Example 4]
In the coating composition for an electrophotographic photosensitive member for the charge generation layer, the same as Example 1 except that p-xylene (boiling point: 138.4 ° C.) is used instead of cyclohexanone.

[Example 5]
In the coating composition for an electrophotographic photosensitive member for the charge generation layer, the same procedure as in Example 1 was carried out except that 63 parts by weight of tetrahydrofuran and 35 parts by weight of cyclohexanone were used instead of 83 parts by weight of tetrahydrofuran and 15 parts by weight of cyclohexanone.

[Example 6]
In the electrophotographic photoreceptor coating composition for the charge generation layer, Example 1 was used except that 58 parts by weight of tetrahydrofuran, 10 parts by weight of cyclohexanone and 10 parts by weight of pyrrolidone were used instead of 83 parts by weight of tetrahydrofuran and 15 parts by weight of cyclohexanone. It is the same.

[Example 7]
In the charge generation layer forming step, instead of discharging the electrophotographic photosensitive member coating composition for the charge generation layer from the discharge nozzle so that the volume of the droplet is 30 pl, it is discharged so that the volume of the droplet is 80 pl. Example 1 is the same as Example 1.

[Example 8]
The charge generation layer forming step is the same as that of Example 1 except that the charge generation layer is formed to have a thickness of 0.8 μm instead of forming the charge generation layer to have a thickness of 0.2 μm. .

[Comparative Example 1]
In the charge generation layer forming step, instead of discharging the electrophotographic photosensitive member coating composition for the charge generation layer from the discharge nozzle so that the volume of the droplet is 30 pl, the discharge is performed so that the volume of the droplet is 300 pl. Example 1 is the same as Example 1.

[Comparative Example 2]
The charge generation layer forming step is the same as that of Example 1 except that the charge generation layer is formed to have a thickness of 1.5 μm instead of forming the charge generation layer to have a thickness of 0.2 μm. .

[Comparative Example 3]
The charge generation layer forming step is the same as Comparative Example 1 except that the charge generation layer is formed to have a thickness of 1.5 μm instead of forming the charge generation layer to have a thickness of 0.2 μm. .

[Comparative Example 4]
In the coating composition for an electrophotographic photosensitive member for the charge generation layer, the same as Example 1 except that 98 parts by weight of tetrahydrofuran was used instead of 83 parts by weight of tetrahydrofuran and 15 parts by weight of cyclohexanone.

[Comparative Example 5]
In the charge generation layer forming step, instead of discharging the electrophotographic photosensitive member coating composition for the charge generation layer from the discharge nozzle so that the volume of the droplet is 30 pl, the discharge is performed so that the volume of the droplet is 300 pl. The same as Comparative Example 4 except that.

[Comparative Example 6]
The charge generation layer forming step is the same as Comparative Example 4 except that the charge generation layer is formed to have a thickness of 1.5 μm instead of forming the charge generation layer to have a thickness of 0.2 μm. .

[Comparative Example 7]
In the coating composition for an electrophotographic photosensitive member for the charge generation layer, the same procedure as in Example 1 was performed except that 45 parts by weight of cyclohexanone and 53 parts by weight of tetrahydrofuran were used instead of 83 parts by weight of tetrahydrofuran and 15 parts by weight of cyclohexanone.

[Comparative Example 8]
In the charge generation layer forming step, instead of discharging the electrophotographic photosensitive member coating composition for the charge generation layer from the discharge nozzle so that the volume of the droplet is 30 pl, it is discharged so that the volume of the droplet is 5 pl. Example 1 is the same as Example 1.

[Comparative Example 9]
In the charge generation layer forming step, instead of discharging the electrophotographic photosensitive member coating composition for the charge generation layer from the discharge nozzle so that the volume of the droplet is 30 pl, it is discharged so that the volume of the droplet is 120 pl. Example 1 is the same as Example 1.

[Comparative Example 10]
The charge generation layer forming step is the same as that of Example 1 except that the charge generation layer is formed to have a thickness of 1.2 μm instead of forming the charge generation layer to have a thickness of 0.2 μm. .

[Evaluation]
About Examples 1-8 and Comparative Examples 1-10, ejection property evaluation, external appearance evaluation, image reproducibility evaluation, image defect evaluation, productivity evaluation, and cost evaluation were performed as follows. The electrophotographic photosensitive member produced by the above method was evaluated by the following evaluation method, and the results are shown in Table 1.

  Note that symbols such as “◯”, “Δ”, and “x” described in the description of each evaluation item are symbols indicating evaluation results used in Table 1. “◯” indicates that it is very excellent, “Δ” indicates that it is practical, and “×” indicates that practical use is difficult.

  Image reproducibility evaluation and image defect evaluation are performed at normal temperature using a device in which the electrophotographic photosensitive member manufactured by the above method is attached to a full-color copying machine (manufactured by Sharp Corporation: AR-C260) using a tandem image forming method. Printing was performed under humidity (25 ° C., 50%) and evaluated.

(Ejection evaluation)
In the charge generation evaluation, the charge generation layer was formed based on the following criteria after the charge generation layer was formed.
○: The discharge nozzle is not clogged.
X: The discharge nozzle is clogged.

(Appearance evaluation)
Appearance evaluation evaluated the formed charge generation layer based on the following reference | standard.
○: The surface is uniform.
Δ: Uneven portions are observed on the surface.
X: The surface is non-uniform.

(Image reproducibility evaluation)
A test chart was printed on the recording medium by the above method and evaluated based on the following criteria.
○: It is clear without blurring or blurring.
Δ: Slight blurring or blurring occurs.
X: Bleeding or blurring occurs.

(Image defect evaluation)
A test chart was printed on the recording medium and evaluated based on the following criteria.
○: Image defects such as fog and black spots do not occur.
Δ: Slight image defects such as fog and black spots occur.
X: Image defects such as fogging and black spots occur.

(Productivity evaluation)
Productivity evaluation was performed based on the following criteria.
○: Repetitive application is small and productivity is high.
(Triangle | delta): Many repeated application | coating and productivity are low.
X: The number of repeated coatings is very high, and the productivity is extremely low.

(Cost evaluation)
Cost evaluation was performed based on the following criteria.
○: Cost is low because the film thickness is thin or productivity is high.
(Triangle | delta): Since film thickness is thick or productivity is low, cost is high.
X: Since the film thickness is very thick or the productivity is very low, the cost is very high.

  About Examples 1-8 and Comparative Examples 1-10, comparative evaluation was carried out according to said method. The results are shown in Table 1.

  As can be seen from Table 1, Examples 1 to 8, which are the present invention, were able to produce an electrophotographic photosensitive member having a charge generation layer with excellent ejection properties and excellent appearance. Further, when the electrophotographic photosensitive member was used, an image having excellent image reproducibility and an image having no image defect could be printed. Furthermore, it was excellent in productivity and cost.

  In the charge generation layer forming step, when the electrophotographic photosensitive member coating composition for the charge generation layer is discharged from the discharge nozzle so that the volume of the droplet is 300 pl (Comparative Example 1), the discharge property remains excellent. However, since the droplets become large, fine unevenness occurs in the formed charge generation layer, and an electrophotographic photosensitive member having a charge generation layer having an excellent appearance cannot be produced. When an image was formed using this electrophotographic photosensitive member, unevenness of the charge generation layer appeared in the image, the image reproducibility was inferior, and an image having an image defect was produced. It was excellent in terms of productivity and cost.

  When the film thickness of the charge generation layer was increased (Comparative Examples 2 and 3), the discharge performance remained excellent, but the surface had a non-uniform charge generation layer, and the charge generation layer had an excellent appearance. An electrophotographic photoreceptor could not be produced. This is presumably because the amount of the high-boiling solvent is so large that it is difficult to volatilize and the applied electrophotographic photoreceptor coating composition is difficult to dry and drips. When an image was formed using this electrophotographic photosensitive member, the image reproducibility was inferior and an image having an image defect was obtained. Further, since the thickness of the charge generation layer is thick, the cost is inferior, and in the case of Comparative Example 2, the productivity is poor because the amount of ejected droplets is small.

  When a coating composition for an electrophotographic photoreceptor not containing a high-boiling solvent was used (Comparative Example 4), the dischargeability was poor and the appearance of the formed charge generation layer was not good. When the high-boiling solvent is not included, the drying is quick, so that when the electrophotographic photoreceptor coating composition is ejected, it becomes easy to dry with the head and cannot be stably ejected. Also, the applied electrophotographic photoreceptor coating composition is It seems that the appearance deteriorated because it dried before flowing sufficiently. When an electrophotographic photosensitive member is produced using such a coating composition for an electrophotographic photosensitive member, when a charge generation layer is formed, a coating failure occurs, and a charge generation layer having a desired uniformity is formed. I couldn't. When an image was formed using this electrophotographic photosensitive member, the image reproducibility was inferior and an image having an image defect was obtained.

  A coating composition for an electrophotographic photosensitive member that does not contain a high boiling point solvent is used, and in the charge generation layer forming step, the coating composition for an electrophotographic photosensitive member for the charge generation layer is made to have a droplet volume of 300 pl from the discharge nozzle. (Comparative Example 5), even when a coating composition for an electrophotographic photosensitive member not containing a high-boiling solvent was used, the discharge property could be secured, but the appearance of the formed charge generation layer was good There wasn't. When discharging by increasing the size of the droplet, it becomes difficult to dry with the head, and it is possible to discharge stably. However, it is thought that the appearance deteriorated because the applied electrophotographic photosensitive material coating composition dries before it sufficiently flows. When an electrophotographic photosensitive member is produced using such a coating composition for an electrophotographic photosensitive member, when a charge generation layer is formed, a coating failure occurs, and a charge generation layer having a desired uniformity is formed. I couldn't. When an image was formed using this electrophotographic photosensitive member, the image reproducibility was inferior and an image having an image defect was obtained. It was excellent in terms of productivity and cost.

  When a coating composition for an electrophotographic photosensitive member that does not contain a high-boiling solvent is used to make the charge generation layer thick (Comparative Example 6), the discharge property is poor and the appearance of the formed charge generation layer is also good. There wasn't. When high-boiling solvents are not included, drying is fast, so it is easy to dry with the head when discharging the electrophotographic photosensitive material coating composition, and it becomes impossible to discharge stably. This is probably because the electrophotographic photoreceptor coating composition does not flow sufficiently. When an electrophotographic photosensitive member is produced using such a coating composition for an electrophotographic photosensitive member, when a charge generation layer is formed, a coating failure occurs, and a charge generation layer having a desired uniformity is formed. I couldn't. When an image was formed using this electrophotographic photosensitive member, the image reproducibility was inferior and an image having an image defect was obtained. Since the droplets are small, it takes time to secure a desired film thickness, resulting in poor productivity, and a high film thickness because the film thickness is thick.

  The electrophotographic photosensitive member coating composition containing a high boiling point solvent in an amount of more than 40 parts by weight (Comparative Example 7) was excellent in dischargeability, but such an electrophotographic photosensitive member coating composition was used. Thus, when an electrophotographic photosensitive member was produced, the surface had a non-uniform charge generation layer. This is considered to be because the high boiling point solvent is difficult to volatilize and the applied electrophotographic photoreceptor coating composition is difficult to dry and droops. When an image was formed using this electrophotographic photosensitive member, the image reproducibility was inferior and an image having an image defect was obtained.

  In the charge generation layer forming step, when the electrophotographic photosensitive member coating composition for the charge generation layer is discharged from the discharge nozzle so that the volume of the droplet is 5 pl (Comparative Example 8), the charge generation layer having an excellent appearance An electrophotographic photoreceptor having the following can be produced. Furthermore, when the electrophotographic photosensitive member was used, an image having excellent image reproducibility and no image defects could be printed. However, the appropriate amount of the liquid was small, and it took too much time for coating, and the productivity was greatly reduced.

  In the charge generation layer forming step, when the electrophotographic photoreceptor coating composition for the charge generation layer is discharged from the discharge nozzle so that the volume of the droplet is 120 pl (Comparative Example 9), the droplet becomes large. As a result, fine unevenness occurred in the formed charge generation layer. When an image was formed using this electrophotographic photosensitive member, unevenness of the charge generation layer appeared in the image, the image reproducibility was inferior, and an image having an image defect was produced.

  When the thickness of the charge generation layer was increased (Comparative Example 10), the charge generation layer had a nonuniform surface. This is presumably because the amount of the high-boiling solvent is so large that it is difficult to volatilize and the applied electrophotographic photoreceptor coating composition is difficult to dry and drips. When an image was formed using this electrophotographic photosensitive member, the image reproducibility was inferior and an image having an image defect was obtained.

It is the schematic which shows the inkjet coating apparatus used by this invention. 1 is a schematic cross-sectional view showing an electrophotographic photosensitive member 10 according to an embodiment of the present invention. 1 is a configuration diagram showing a simplified configuration of an image forming apparatus 21 according to the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Conductive base | substrate 2 Rotating shaft 3 Guide rail 4 Discharge part 5 Conveyance path 6 Storage tank 7 Coating composition liquid droplet for electrophotographic photoreceptors 10, 22 Electrophotographic photoreceptor 11 Conductive support body 12 Charge generation layer 13 Charge transport layer DESCRIPTION OF SYMBOLS 14 Photosensitive layer 15 Undercoat layer 21 Image forming apparatus 23 Charging device 24 Developing device 25 Transfer charging device 26 Cleaner 27 Fixing device 31, 32 Arrow 33 Recording medium 34 Laser beam

Claims (7)

A method for producing an electrophotographic photoreceptor in which a charge generation layer is formed by discharging a coating composition for an electrophotographic photoreceptor as droplets,
The electrophotographic photoreceptor coating composition includes a charge generating material, a binder resin, and a solvent,
The solvent includes one or more high-boiling solvents having a boiling point of 120 ° C. or higher and 260 ° C. or lower,
The high boiling point solvent contains 5 parts by weight or more and 40 parts by weight or less in 100 parts by weight of the coating composition for an electrophotographic photosensitive member,
The volume of the droplet is 10 pl or more and 100 pl or less,
A method for producing an electrophotographic photosensitive member, comprising forming a charge generation layer so that a film thickness d of the charge generation layer is 0.01 μm <d <1 μm.   2. The method for producing an electrophotographic photosensitive member according to claim 1, wherein the charge generation material is a titanyl phthalocyanine compound.   3. The electrophotographic photosensitive member according to claim 1, wherein the high-boiling solvent is one or more high-boiling solvents selected from cyclohexanone, pyrrolidone, n-methylpyrrolidone and p-xylene. Method.   The method for producing an electrophotographic photosensitive member according to claim 1, wherein the solvent includes a low boiling point solvent having a boiling point of 30 ° C. or higher and lower than 120 ° C. 5.   The method for producing an electrophotographic photosensitive member according to claim 4, wherein the low boiling point solvent has a difference in boiling point from the high boiling point solvent of 70 ° C. or more.   An electrophotographic photosensitive member produced by the method for producing an electrophotographic photosensitive member according to claim 1.   An image forming apparatus using the electrophotographic photosensitive member according to claim 6.

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