JP2009282186A - Electrophotographic photoreceptor and method for manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrophotographic photoreceptor which has wear resistance effectively increased with a limited addition amount of filler, and at the same time has residual potential suppressed in increase, and thereby maintaining both of a long life and excellent printing quality, and to provide a method for the same. <P>SOLUTION: In a process of applying and forming a charge transporting layer as the outermost layer of a multilayer organic photoreceptor by a nozzle coating method, the number of revolution of a conductive support is kept at a given value or more in at least either a coating or leveling step to thereby distribute a filler having a larger specific gravity only in a photoreceptor surface with a high density by the effect of centrifugal force. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic photosensitive member used in electrophotographic apparatuses and process cartridges such as copying machines, printers, and facsimiles, and a method for manufacturing the same, and in particular, printing by coating and forming on a conductive support by a nozzle coat coating method. The present invention relates to a long-life electrophotographic photosensitive member having excellent electrophotographic characteristics and low wear, and a method for producing the same.

  In recent years, the advantages of electrophotographic devices such as high speed, low noise, high image quality, and the ability to record on plain paper have attracted attention, and not only in copying machines but also in printers and facsimiles. It is becoming popular. Furthermore, as a recent trend, in the field of printers and facsimiles, usage forms have shifted from office use to personal use, and further miniaturization, cost reduction, and maintenance-free operation are required. On the other hand, with the improvement of image processing techniques such as colorization of documents, there is a need for image forming techniques with higher resolution and quality.

  As an electrophotographic photosensitive member (hereinafter, also referred to as a photosensitive member) used in such an electrophotographic apparatus, an organic photosensitive member made of an organic photoconductive material having an advantage such as being inexpensive and non-polluting. Has been actively developed and is currently installed in many devices. Although there are photosensitive layers with a single layer structure, most of the practically used photoreceptors are a conductive support and a charge generation layer containing a charge generation material and a charge transport layer containing a charge transport material sequentially. It is a laminated type photoreceptor whose function is separated by forming. Further, in order to improve the characteristics of the photosensitive member, a photosensitive member in which an undercoat layer is provided between the conductive support and the photosensitive layer has become the mainstream.

  On the other hand, since this organic photoreceptor has low hardness and poor wear resistance, durability becomes a problem when used for a long time. In order to improve the wear resistance, a hard material such as metal oxide is mixed as a filler, but increasing the amount of this filler improves the wear resistance, but the residual potential remains on the photoreceptor. There is a drawback that it is easy, so the amount of addition is limited, and the effect is limited.

  Known methods for producing a photoreceptor include a dip coating method, a ring coating method, a spray coating method, and a nozzle coat coating method.

  Among these, the dip coating method is to form a coating film by immersing a conductive support in a coating solution, and has the advantage that a coating film excellent in surface smoothness is obtained, but a large coating device is required. Therefore, there is a drawback that the replacement time and the paint loss at the time of changing the product are large.

  Also, in the ring coating method, a ring-shaped coating head discharges the coating liquid onto the outer peripheral surface of the cylindrical shaft core, and after applying the elastic member forming composition on the outer periphery of the shaft core, A conductive elastic layer is formed by curing the elastic member forming composition (see, for example, Patent Document 1). This ring coating method has an advantage that it can be produced with a small amount of coating liquid, but has a drawback that a slight variation in the gap between the ring and the support greatly affects the uniformity of the coating film.

  In the spray coating method, in order to apply the photosensitive layer, the conductive support is attached and rotated, and the coating liquid is ejected together with the carrier gas while scanning the spray gun with a scanning device to form the conductive support. This is performed by spraying (see, for example, Patent Document 2). This spray coating method can be prepared with a small amount of coating liquid, and can be switched and maintained relatively easily. There is a disadvantage that loss is large.

  Regarding the method for producing an undercoat layer by this spray coating method, the applicant of the present application is caused by coating film defects resulting from the precipitation of agglomerates during continuous coating, and adhesion of the coating liquid to the coating liquid discharge port. A method for manufacturing an electrophotographic photosensitive member has been proposed that improves film thickness unevenness and can provide stable and excellent print quality even during continuous coating (see Patent Document 3).

  The technique of this (patent document 3) is the functional fine powder about the functional fine powder (filler), binder resin, and organic solvent which are contained in the coating liquid in the coating formation of the undercoat layer by the spray coating method. The mixing ratio of (A) and binder resin (B) is 0.75 <A / B <2.5 in terms of weight, the primary particle size (X) of the functional fine powder (A) is 40 nm <X <250 nm, organic The boiling point of at least one of the system solvents is 150 ° C. or higher.

Next, another method for producing a photoreceptor will be described. In the nozzle coat coating method, the paint is sprayed and applied as a liquid at a short distance of 1 mm or less between the nozzle and the support to form a coating film. It is. In this respect, the spray coating method has a flight distance of several centimeters, and the coating is applied in the form of a mist with a carrier gas or the like. Because of these differences, the nozzle coat coating method can form a coating film in a limited range compared to the spray coat coating method. The coating can be performed with almost 100% adhesion and little paint loss.
JP 2006-335892 A Japanese Patent Laid-Open No. 8-15876 JP 2008-9001 A

  As described above, organic photoreceptors have low hardness and inferior wear resistance, so durability becomes a problem when used for a long time. For this reason, fillers are conventionally mixed for the purpose of improving wear resistance. However, when the amount of filler is increased, wear resistance is improved, but the residual potential tends to remain on the photoreceptor. . Therefore, the amount of filler added has been limited.

  According to the method for producing an electrophotographic photoreceptor of Patent Document 3, it is possible to improve coating film defects due to precipitation of aggregates during coating, film thickness unevenness due to adhesion of the coating liquid to the nozzle, and the like. Become.

  However, this technique has not been able to improve both the wear resistance and the residual potential. That is, if the abrasion resistance of the photosensitive layer or the charge transport layer is improved, a large residual potential remains, and if no residual potential is left, the wear resistance decreases. It was only to harmonize both characteristics, and basically left it to nature, and it was impossible to control both. There is a demand for a new technique that can suppress the amount of filler added, sufficiently ensure the wear resistance of the charge transport layer while maintaining a limited amount, and that does not leave a residual potential.

  The present invention effectively increases the wear resistance with a limited amount of filler added, and at the same time suppresses the increase in residual potential and maintains both long life and excellent print quality, and its production A method is provided.

  In order to solve such problems, the electrophotographic photosensitive member of the present invention comprises a cylindrical conductive support and a cylindrical photosensitive layer formed on the conductive support, and the photosensitive layer is a filler. And a coating solution in which a charge transport material is dispersed in a binder resin solution and sprayed onto a conductive support, and the filler has a heavier specific gravity than the charge transport material and the binder resin, and the photosensitive layer. The main feature is that it is distributed in large numbers on the surface side.

  In addition, the method for producing an electrophotographic photoreceptor of the present invention produces a coating liquid in which a charge transporting material and a filler having a specific gravity heavier than that of the binder resin are dispersed together with the charge transporting material in a binder resin solution. A conductive support is supported in the axial direction, rotated at a predetermined peripheral speed or more around the axis of the conductive support, a coating solution is sprayed onto the conductive support to form a photosensitive layer, and sprayed. After completion, the conductive support is rotated at a predetermined peripheral speed for a predetermined time to perform leveling, and the amount of filler distribution in the photosensitive layer is determined by the centrifugal force during at least one of rotation during coating and leveling. The main feature is to make it larger.

  According to the present invention, fillers such as metal oxide can be distributed in a high density on the surface layer of the photosensitive layer or charge transport layer that most affects the durability, and effective with a limited filler addition amount. In addition, the electrophotographic photosensitive member has a long-life electrophotographic photosensitive member that has an electrophotographic characteristic with excellent print quality and low wear, and at the same time, suppresses the increase in residual potential by reducing the amount of filler in the inner layer. A manufacturing method can be provided.

  The invention of claim 1 of the present invention comprises a cylindrical conductive support, and a cylindrical photosensitive layer formed on the conductive support, wherein the photosensitive layer comprises a binder resin and a charge transport material. An electrophotographic photosensitive member having a structure in which a coating solution dispersed in a dissolving solution is sprayed onto a conductive support and has a specific gravity greater than that of a charge transport material and a binder resin, and the surface of the photosensitive layer The electrophotographic photosensitive member is characterized by being distributed a lot on the side.

  With this configuration, the coating material applied to the surface of the conductive support rotates during application and leveling, and therefore the filler in the coating material is distributed more biased toward the surface layer than the inner layer due to centrifugal force. As a result, there are many fillers that have an effect on wear resistance near the surface of the photosensitive layer, and the amount of filler on the inner layer side is reduced, so that the increase in residual potential can be suppressed to a small amount. It is possible to manufacture an electrophotographic photosensitive member that can simultaneously realize improvement of image quality and prevention of image quality degradation.

  A second aspect of the present invention includes a cylindrical conductive support, a charge generation layer stacked on the conductive support, and a charge transport layer stacked on the charge generation layer. The transport layer is an electrophotographic photosensitive member having a structure in which a coating liquid in which a filler and a charge transport material are dispersed in a binder resin solution is sprayed onto a conductive support, and the filler is formed of a charge transport material and An electrophotographic photosensitive member having a specific gravity heavier than that of a binder resin and being distributed more on the surface side of the charge transport layer.

  With this configuration, the coating applied to the charge generation layer rotates during coating and leveling, and therefore the filler in the coating is distributed more unevenly from the inner layer to the surface layer due to centrifugal force. As a result, there are many fillers that have an effect on wear resistance near the surface of the photosensitive layer, and the amount of filler on the inner layer side is reduced, so that the increase in residual potential can be suppressed to a small amount. It is possible to manufacture an electrophotographic photosensitive member that can simultaneously realize improvement of image quality and prevention of image quality degradation.

  The invention of claim 3 of the present invention is a form dependent on the invention of claim 1 or claim 2, wherein the weight ratio of the filler is 5% or more and 20% or less with respect to the nonvolatile component. An electrophotographic photoreceptor.

  With this configuration, the filler in the paint moves with a smooth and stable quality by centrifugal force and is distributed unevenly in the surface layer. Thereby, it is possible to produce an electrophotographic photosensitive member having an electrophotographic characteristic excellent in print quality and having little wear.

  The invention of claim 4 of the present invention is a form subordinate to the invention of claim 1 or claim 2, wherein the specific gravity of the filler is 2 to 4 times the binder resin. An electrophotographic photoreceptor.

  With this configuration, the centrifugal force that moves the filler in the paint with a smooth and stable quality acts, and is distributed unevenly in the surface layer. Thereby, it is possible to produce an electrophotographic photosensitive member having an electrophotographic characteristic excellent in print quality and having little wear.

  The invention according to claim 5 of the present invention is a form dependent on the invention of claim 2, wherein the filler distribution amount is 50% or more in a range of 1/3 depth from the surface of the charge transport layer. An electrophotographic photosensitive member is characterized.

  With this configuration, the surface layer of the photosensitive layer can be imparted with wear resistance, and the amount of filler can be reduced on the inner layer side to suppress the increase in residual potential to a slight amount.

  According to a sixth aspect of the present invention, there is provided a cylindrical conductive support and a cylindrical photosensitive layer formed on the conductive support, wherein the photosensitive layer comprises a binder resin and a charge transport material. An electrophotographic photosensitive member having a structure in which a coating solution dispersed in a dissolving solution is sprayed onto a conductive support and has a specific gravity greater than that of a charge transport material and a binder resin, and the surface of the photosensitive layer An electron having a weight ratio of filler of 5% or more and 20% or less of the non-volatile component, and a filler specific gravity of 2 to 4 times that of the binder resin. It is a photographic photoreceptor.

  With this configuration, the coating material applied to the surface of the conductive support rotates during application and leveling, and therefore the filler in the coating material is distributed more biased toward the surface layer than the inner layer due to centrifugal force. As a result, there are many fillers that have an effect on wear resistance near the surface of the photosensitive layer, and the amount of filler on the inner layer side is reduced, so that the increase in residual potential can be suppressed to a small amount. It is possible to manufacture an electrophotographic photosensitive member that can simultaneously realize improvement of image quality and prevention of image quality degradation. Furthermore, the weight ratio of the filler is 5% or more and 20% or less with respect to the non-volatile component, and the specific gravity of the filler is 2 times or more and 4 times or less with respect to the binder resin. And a long-life electrophotographic photoreceptor with little wear.

  A seventh aspect of the present invention includes a cylindrical conductive support, a charge generation layer laminated on the conductive support, and a charge transport layer laminated on the charge generation layer, The transport layer is an electrophotographic photosensitive member having a structure in which a coating liquid in which a filler and a charge transport material are dispersed in a binder resin solution is sprayed onto a conductive support, and the filler is formed of a charge transport material and a charge transport material. It has a heavier specific gravity than the binder resin, is distributed more on the surface side of the charge transport layer, the filler weight ratio is 5% or more and 20% or less with respect to the non-volatile component, and the filler specific gravity is more than twice that of the binder resin. And an amount of filler distribution is 50% or more in a depth range of 1/3 from the surface of the charge transport layer.

  With this configuration, the coating applied to the charge generation layer rotates during coating and leveling, and therefore the filler in the coating is distributed more unevenly from the inner layer to the surface layer due to centrifugal force. As a result, there are many fillers that have an effect on wear resistance near the surface of the photosensitive layer, and the amount of filler on the inner layer side is reduced, so that the increase in residual potential can be suppressed to a small amount. It is possible to manufacture an electrophotographic photosensitive member that can simultaneously realize improvement of image quality and prevention of image quality degradation. Furthermore, the weight ratio of the filler is 5% or more and 20% or less with respect to the non-volatile component, and the specific gravity of the filler is 2 times or more and 4 times or less with respect to the binder resin. And a long-life electrophotographic photoreceptor with little wear. Further, the distribution amount of the filler is 50% or more in the range of 1/3 depth from the surface of the charge transporting layer, so that the surface layer of the photosensitive layer is imparted with an abrasion resistance property, and the filler is formed on the inner layer side. Therefore, the increase in the residual potential can be suppressed to a slight amount.

  The invention according to claim 8 of the present invention is to provide a coating liquid in which a charge transport material and a filler having a specific gravity heavier than that of the binder resin are dispersed together with the charge transport material in a solution of the binder resin, thereby forming a cylindrical conductive support. The body is supported in the axial direction, rotated about the axis of the conductive support at a predetermined peripheral speed or more, and a coating solution is sprayed onto the conductive support to form a photosensitive layer. The photosensitive support is rotated at a predetermined peripheral speed or higher for a predetermined time to perform leveling, and the amount of filler distribution in the photosensitive layer is increased on the surface side of the photosensitive layer by centrifugal force during at least one of rotation during coating and leveling. This is a method for producing an electrophotographic photosensitive member.

  With this configuration, the paint applied to the surface of the conductive support rotates during rotation of at least one of application and leveling, so the filler in the paint is distributed more unevenly from the inner layer to the surface layer side due to centrifugal force. To do. As a result, there are many fillers that have an effect on wear resistance near the surface of the photosensitive layer, and the amount of filler on the inner layer side is reduced, so that the increase in residual potential can be suppressed to a small amount. It is possible to manufacture an electrophotographic photosensitive member that can simultaneously realize improvement of image quality and prevention of image quality degradation.

  According to a ninth aspect of the present invention, there is provided a coating liquid in which a charge transport material and a filler having a specific gravity heavier than that of the binder resin are dispersed together with the charge transport material in a binder resin solution, and the charge generation layer is formed on the surface. The formed cylindrical conductive support is supported in the axial direction, rotated around the axis of the conductive support at a predetermined peripheral speed or more, and the coating liquid is sprayed onto the conductive support to charge A transport layer is formed, and after spraying, the conductive support is rotated for a predetermined time at a predetermined peripheral speed or higher for leveling, and at least one of rotation during coating and leveling is performed by centrifugal force during the rotation of the filler in the charge transport layer. An electrophotographic photoreceptor manufacturing method is characterized in that the distribution amount is increased on the surface side of the charge transport layer.

  With this configuration, the coating material applied to the charge generation layer rotates during rotation of at least one of application and leveling, and therefore the filler in the coating is distributed more unevenly from the inner layer to the surface layer side due to centrifugal force. As a result, there are many fillers that have an effect on wear resistance near the surface of the photosensitive layer, and the amount of filler on the inner layer side is reduced, so that the increase in residual potential can be suppressed to a small amount. It is possible to manufacture an electrophotographic photosensitive member that can simultaneously realize improvement of image quality and prevention of image quality degradation.

  The invention of claim 10 of the present invention is a form dependent on the invention of claim 8 or claim 9, wherein the peripheral speed of the conductive support after spraying is set to 200 mm / s or more and 350 mm / s or less. This is a method for producing an electrophotographic photosensitive member.

  With this configuration, the centrifugal force that moves the filler in the paint with a smooth and stable quality acts, and is distributed unevenly in the surface layer. Thereby, it is possible to produce an electrophotographic photosensitive member having an electrophotographic characteristic excellent in print quality and having little wear.

  An eleventh aspect of the present invention is an embodiment dependent on the eighth or ninth aspect of the invention, wherein the electroconductive support is further rotated for 120 seconds or more after the spraying is completed. This is a method for producing a photoreceptor.

  With this configuration, during leveling, the filler in the paint is distributed more than a predetermined ratio by centrifugal force more biased toward the surface layer than the inner layer. As a result, there are many fillers that are effective in wear resistance near the surface of the photosensitive layer, and the amount of filler on the inner layer side is reduced, and the increase in residual potential can be suppressed to a slight amount.

  The invention of claim 12 of the present invention is a form dependent on the invention of claim 8 or claim 9, wherein the weight ratio of the filler is 5% or more and 20% or less with respect to the nonvolatile component. This is a method for producing an electrophotographic photoreceptor.

  With this configuration, the filler in the paint moves with a smooth and stable quality by centrifugal force and is distributed unevenly in the surface layer. Thereby, it is possible to produce an electrophotographic photosensitive member having an electrophotographic characteristic excellent in print quality and having little wear.

  The invention according to claim 13 of the present invention is a form dependent on the invention of claim 8 or claim 9, wherein the specific gravity of the filler is not less than 2 times and not more than 4 times that of the binder resin. This is a method for producing an electrophotographic photoreceptor.

  With this configuration, the centrifugal force that moves the filler in the paint with a smooth and stable quality acts, and is distributed unevenly in the surface layer. Thereby, it is possible to produce an electrophotographic photosensitive member having an electrophotographic characteristic excellent in print quality and having little wear.

  The invention according to claim 14 of the present invention is a form dependent on the invention according to claim 9, wherein the filler distribution is 50% or more in a range of 1/3 depth from the surface of the charge transport layer. And an electrophotographic photosensitive member manufacturing method.

  With this configuration, the surface layer of the photosensitive layer can be imparted with wear resistance, and the amount of filler can be reduced on the inner layer side to suppress the increase in residual potential to a slight amount.

  According to the fifteenth aspect of the present invention, there is provided a coating liquid in which a charge transport material and a filler having a specific gravity heavier than that of the binder resin are dispersed together with the charge transport material in a binder resin solution, thereby forming a cylindrical conductive support. The body is supported in the axial direction, rotated about the axis of the conductive support at a predetermined peripheral speed or more, and a coating solution is sprayed onto the conductive support to form a photosensitive layer. The photosensitive support is rotated at a predetermined peripheral speed or higher for a predetermined time to perform leveling, and the amount of filler distribution in the photosensitive layer is increased on the surface side of the photosensitive layer by centrifugal force during at least one of rotation during coating and leveling. A method for producing an electrophotographic photoreceptor, wherein when a coating solution is produced, the weight ratio of the filler is 5% or more and 20% or less with respect to the nonvolatile component, and the specific gravity of the filler is a binder resin. In contrast, the peripheral speed of the conductive support after the completion of spraying is set to 200 mm / s or more and 350 mm / s or less after the spraying is completed, and the conductive support is rotated for 120 seconds or more after the spraying is completed. An electrophotographic photosensitive member manufacturing method characterized by comprising:

  With this configuration, the paint applied to the surface of the conductive support rotates during rotation of at least one of application and leveling, so the filler in the paint is distributed more unevenly from the inner layer to the surface layer side due to centrifugal force. To do. As a result, there are many fillers that have an effect on wear resistance near the surface of the photosensitive layer, and the amount of filler on the inner layer side is reduced, so that the increase in residual potential can be suppressed to a small amount. It is possible to manufacture an electrophotographic photosensitive member that can simultaneously realize improvement of image quality and prevention of image quality degradation. Furthermore, the peripheral speed of the conductive support after the spraying is set to 200 mm / s or more and 350 mm / s or less, and the weight ratio of the filler is set to 5% or more and 20% or less with respect to the nonvolatile component, and the specific gravity of the filler is By making it 2 times or more and 4 times or less with respect to the binder resin, centrifugal force that moves the filler in the paint with a smooth and stable quality acts, and has electrophotographic characteristics with excellent printing quality, In addition, a long-life electrophotographic photosensitive member with little wear can be produced. In addition, since the conductive support was further rotated for 120 seconds or more after the spraying was completed, there were many fillers effective in abrasion resistance near the surface of the photosensitive layer, and the amount of filler on the inner layer side was small. Thus, the increase in the residual potential can be suppressed to a slight amount.

  According to a sixteenth aspect of the present invention, there is provided an electrophotographic photosensitive member according to the fifteenth aspect, wherein the weight concentration of the non-volatile component to the organic solvent is 9% to 12%. It is a manufacturing method.

  With this configuration, moderate drying occurs, the filler particles can be distributed unevenly to the surface layer side, the leveling time after coating is short, the surface after coating does not become uneven, and the photoreceptor characteristics Will improve.

  According to a seventeenth aspect of the present invention, there is provided a coating liquid in which a charge transporting substance and a filler having a specific gravity heavier than that of the binder resin are dispersed together with the charge transporting substance in a binder resin solution, and the charge generation layer is formed on the surface. The formed cylindrical conductive support is supported in the axial direction, rotated around the axis of the conductive support at a predetermined peripheral speed or more, and the coating liquid is sprayed onto the conductive support to charge A transport layer is formed, and after spraying, the conductive support is rotated for a predetermined time at a predetermined peripheral speed or higher for leveling, and at least one of rotation during coating and leveling is performed by centrifugal force during the rotation of the filler in the charge transport layer. A method for producing an electrophotographic photoreceptor in which the distribution amount is increased on the surface side of the charge transport layer, and when the coating liquid is produced, if the weight ratio of the filler is 5% or more and 20% or less with respect to the nonvolatile component In addition, after the filler has a specific gravity of 2 to 4 times that of the binder resin, and the peripheral speed of the conductive support after the spraying is 200 mm / s or more and 350 mm / s or less, and after the spraying is finished An electrophotographic photosensitive member production method, wherein the conductive support is rotated for 120 seconds or more.

  With this configuration, the paint applied to the surface of the conductive support rotates during rotation of at least one of application and leveling, so the filler in the paint is distributed more unevenly from the inner layer to the surface layer side due to centrifugal force. To do. As a result, there are many fillers that have an effect on wear resistance near the surface of the photosensitive layer, and the amount of filler on the inner layer side is reduced, so that the increase in residual potential can be suppressed to a small amount. It is possible to manufacture an electrophotographic photosensitive member that can simultaneously realize improvement of image quality and prevention of image quality degradation. Furthermore, the peripheral speed of the conductive support after the spraying is set to 200 mm / s or more and 350 mm / s or less, and the weight ratio of the filler is set to 5% or more and 20% or less with respect to the nonvolatile component, and the specific gravity of the filler is By making it 2 times or more and 4 times or less with respect to the binder resin, centrifugal force that moves the filler in the paint with a smooth and stable quality acts, and has electrophotographic characteristics with excellent printing quality, In addition, a long-life electrophotographic photosensitive member with little wear can be produced. In addition, since the conductive support was further rotated for 120 seconds or more after the spraying was completed, there were many fillers effective in abrasion resistance near the surface of the photosensitive layer, and the amount of filler on the inner layer side was small. Thus, the increase in the residual potential can be suppressed to a slight amount. Further, by setting the filler distribution to 50% or more in the range of 1/3 depth from the surface of the charge transport layer, the surface layer of the photosensitive layer is imparted with an abrasion resistance property, and the filler layer is formed on the inner layer side. The increase in residual potential can be suppressed to a slight amount by reducing the amount.

  According to an eighteenth aspect of the present invention, there is provided an electrophotographic photosensitive member according to the seventeenth aspect, wherein the weight concentration of the non-volatile component to the organic solvent is 9% to 12%. It is a manufacturing method.

  With this configuration, due to this configuration, moderate drying occurs, the filler particles can be distributed unevenly toward the surface layer side, the leveling time after coating is short, and the surface after coating does not become uneven. The photoreceptor characteristics are improved.

(Embodiment 1)
The electrophotographic photoreceptor and the manufacturing method thereof according to Embodiment 1 of the present invention will be described. FIG. 1 is a cross-sectional view schematically showing a configuration of an electrophotographic photosensitive member according to Embodiment 1 of the present invention, and FIG. 2 is a spray coating apparatus used in the manufacturing method of the electrophotographic photosensitive member according to Embodiment 1 of the present invention. FIG. 3 is a schematic diagram showing the configuration of a dip coating apparatus for forming a charge generation layer used in the method for producing an electrophotographic photosensitive member according to Embodiment 1 of the present invention, and FIG. 4 is a schematic diagram showing the configuration of the present invention. FIG. 5 is a schematic diagram showing the configuration of a nozzle coat coating apparatus for forming a charge transport layer used in the method for producing an electrophotographic photoreceptor in Embodiment 1, and FIG. 5 is a tomogram of the electrophotographic photoreceptor in Embodiment 1 of the present invention. It is a figure which shows a photograph.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  In FIG. 1, an electrophotographic photoreceptor 10 is formed by laminating an undercoat layer 12, a charge generation layer 13, and a charge transport layer 14 in this order on a conductive support 11. In the charge transport layer 14, the filler 14a in the binder resin 14b is distributed in a large amount on the surface layer side.

  In addition, as the electrophotographic photoreceptor 10, the undercoat layer 12, the charge generation layer 13, and the charge transport layer 14 are not formed in this order on the conductive support 11, but a photosensitive layer of an organic photoconductor material is formed as a single layer. When the structure is formed on the conductive support 11, the following description is basically the same. That is, instead of forming the undercoat layer 12, the charge generation layer 13, and the charge transport layer 14, only one photosensitive layer is formed on the conductive support 11. Although it is a single layer, since it is the same as that described in the charge transport layer 14 described later, the case of this single layer structure is not specifically described as another form.

  First, the conductive support 11 will be described. The conductive support 11 may be any material as long as it has a conventionally known conductivity. For example, the conductive support 11 may be a metal material such as aluminum, a metal material deposited on plastic or paper, or provided with conductivity by a conductive paint, or a molded conductive plastic. Used.

  Among them, a tube obtained by machining an aluminum alloy or a sheet obtained by evaporating aluminum on a polyethylene terephthalate film is often used as the conductive support 11. In the case where an aluminum tube is used as the conductive support 11, cleaning with a surfactant or an organic solvent is required before the undercoat layer 12 is formed. This is because inadequate cleaning of the aluminum tube may cause an image defect or a decrease in adhesion due to an electrical failure due to the attached metal cutting.

  Next, the undercoat layer 12 formed on the conductive support 11 will be described. The undercoat layer 12 is formed by spraying the coating liquid onto the conductive support 11 from a position several cm away from the spray gun by a spray coating method. The coating liquid used when forming the undercoat layer 12 by a spray coating method consists of a filler, a binder resin, and an organic solvent. As the filler, for example, titanium oxide, zinc oxide, aluminum oxide (alumina), or the like is used. Preferably, titanium oxide is used in particular. Examples of the binder resin include polyamide resin, butyral resin, alkyd resin, melamine resin, polyester resin, and phenol resin. Preferably, a polyamide resin is particularly used. The filler (A) and the binder resin (B) have a weight ratio (A / B) in the range of 0.75 <A / B <2.5. The filler has a primary particle diameter (X) in the range of 40 nm <X <250 nm. For example, a filler having a primary particle diameter of 70 nm, 120 nm, 210 nm, or the like is used.

  Examples of the organic solvent include (1) alcohols having 3 or less carbon atoms such as methanol, ethanol, n-propanol and isopropanol having a relatively high vapor pressure, and (2) n- having a relatively low vapor pressure. Alcohols having 4 or more carbon atoms such as butanol, n-pentanol, n-hexanol, (3) benzyl alcohol, isophorone, alcohols having a boiling point of cyclohexanone of 150 ° C. or higher, (4) acetone, cyclohexanone, methyl ethyl ketone, methyl Ketones such as isobutyl ketone; (5) ethers such as tetrahydrofuran, 1,3-dioxolane and 1,4-dioxane; (6) esters such as methyl acetate and ethyl acetate; (7) benzene, toluene and xylene. And aromatics.

  One or a mixture of two or more organic solvents can be used. Moreover, in order to make the undercoat layer 12 into a desired film thickness, for example, the organic solvent adjusts the concentration of the non-volatile components (filler and binder resin) in the paint for the undercoat layer in the range of 3 to 30% by weight. Use. Preferably, a ternary system of methanol, butanol, and benzyl alcohol is used as the organic solvent.

  The spray coating apparatus for forming the undercoat layer 12 may be any apparatus as long as the coating liquid having the above configuration can be uniformly formed on the entire conductive support 11. When the conductive support 11 is an aluminum tube, for example, a spray coating apparatus as shown in FIG. 2 is used.

  FIG. 2 shows the configuration of a spray coating apparatus for forming the undercoat layer 12 used in the method of manufacturing the electrophotographic photosensitive member of the first embodiment. The spray gun used at this time may be any one of an air spray gun, an airless spray gun, and an electrostatic spray gun, for example.

  In the spray coating apparatus 20 shown in FIG. 2, the conductive support 11 is vertically held by one support fixing jig 21 and tilted by 90 degrees, and then the conductive support is supported by the other support fixing jig 22. The body 11 is fixed. In this state, the rotation of the conductive support 11 is started, the coating liquid 24 is sprayed from the spray gun 23, and the spray gun 23 is scanned in the axial direction of the conductive support 11, or the spray gun 23 is fixed. Then, the undercoat layer 12 is formed by moving the conductive support 11 in the axial direction.

  At this time, by continuously rotating the conductive support 11 even after the completion of coating, for example, for 5 seconds or more, the volatilization promotion of the solvent and the leveling effect can be exhibited simultaneously. After the coating liquid sprayed in a mist form by the spray gun reaches the conductive support 11, a smooth surface coating film is formed by the leveling action and the volatilization action. After passing through this step, if the conductive support 11 is returned to the vertical direction again, a coating film of the undercoat layer 12 having no film defect can be formed.

  Next, the charge generation layer 13 will be described. After the undercoat layer 12 is formed on the conductive support 11, a charge generation layer 13 made of a charge generation material and a binder resin is used using a charge generation layer coating material made of a charge generation material, a binder resin, and an organic solvent. Is laminated on the undercoat layer 12 by a dip coating method or the like.

  Here, as the charge generation material, for example, phthalocyanine pigments, perylene pigments, anthraquinone pigments, squarylium pigments, and the like can be used. Of these, phthalocyanine pigments are suitable, and oxotitanium phthalocyanine is particularly preferred.

  In addition, as the binder resin of the charge generation layer 13, for example, resins such as polyvinyl butyral, polyvinyl acetal, and polyester can be used. However, coating film formability, solubility in a coating solvent, and stability as a coating material can be used. In view of the properties, polyvinyl butyral is particularly preferable.

  The constituent ratio of the charge generation material and the binder resin is, for example, in a weight ratio in which the binder resin is 1 and the charge generation material is in the range of 0.5 to 5.

  Furthermore, it is desirable to select an organic solvent for dissolving the binder resin to disperse the charge generation material and forming the charge generation layer coating material from those that do not dissolve the lower layer. Specific examples of organic solvents include alcohols such as methanol, butanol, and benzyl alcohol; ketones such as acetone, cyclohexanone, methyl ethyl ketone, and methyl isobutyl ketone; tetrahydrofuran, 1,3-dioxolane, 1,4-dioxane, and the like. Ethers, esters such as methyl acetate and ethyl acetate, and aromatics such as benzene, toluene and xylene. These organic solvents can be used alone or in combination of two or more. In addition, this organic solvent has a non-volatile component (charge generation material and binder resin) concentration of 1 wt% to 15 wt% in the charge generation layer coating material, for example, in order to make the charge generation layer 13 a desired film thickness. Adjust and use within the range.

  Using the charge generation layer coating material thus adjusted, for example, the charge generation layer 13 is formed by the dip coating apparatus 30 shown in FIG. Specifically, an aluminum tube 31 with an undercoat layer 12 formed on a conductive support 11 is attached to a movable part 32 equipped with a fixing jig, and immersed in a pot 34 containing a charge generation layer coating material 33. Thereafter, the charge generation layer 13 is formed by pulling up at a predetermined speed.

  A circulation pump 35 and a filter unit 36 are piped to the pot 34. After the dip coating, the charge generation layer 13 having a thickness in the range of about 0.05 μm to 1 μm is formed by evaporating the solvent by natural drying or heat drying. In FIG. 3, reference numeral “37” is a ball screw for moving the movable part 32 up and down, and reference numeral “38” is a motor for rotating the ball screw 37.

  Next, the charge transport layer 14 will be described. After forming the undercoat layer 12 and the charge generation layer 13 on the conductive support 11, a charge transport material, a charge transport material comprising a charge transport material, a filler 14a, a binder resin 14b, and an organic solvent, The charge transport layer 14 composed of the filler 14a and the binder resin 14b is laminated on the charge generation layer 13 by a coating method such as a nozzle coat coating method and a coating apparatus.

  Here, as the charge transport material, for example, an electron donating oxazole compound, oxadiazole compound, pyrazoline compound, hydrazone compound, stilbene compound, tetraphenylbutadiene compound, biphenyl compound, and derivatives of these compounds should be used. Can do.

  As the filler 14a, in addition to aluminum oxide (alumina), a hexagonal close-packed material having the same crystal structure as that of alumina, such as beryllium oxide, high-temperature type quartz, zinc oxide, and w-boron nitride, silica, and the like are used. .

  In addition, as the binder resin 14b, for example, a resin such as polycarbonate, polyester, polysulfone, polyarylate, polymethyl methacrylate, etc. can be used, but compatibility with the charge transporting material, film strength, solubility in the coating solvent. Polycarbonate is particularly preferable from the viewpoint of stability as a coating material.

  The composition ratio of the charge transport material, filler 14a and binder resin 14b is, for example, a weight ratio in which the binder resin is 1 and the filler 14a is 0.1 to 2 and the charge transport material is 0.25 to 3. Used. Further, the weight ratio of the filler 14a to the non-volatile components (charge transporting material and binder resin 14b) in the coating for the charge transport layer is 5% or more and 20% or less.

  In addition to the charge transport material, the filler 14a, and the binder resin 14b, for example, an antioxidant or an ultraviolet absorber may be added for the purpose of preventing the deterioration of these materials. Furthermore, for example, silicone oil or fluororesin can be added for the purpose of improving the lubricity of the surface of the charge transport layer.

  Furthermore, examples of the organic solvent for dissolving the charge transport material and the binder resin 14b to form a charge transport layer coating include chlorinated hydrocarbons such as dichloromethane and chloroform, tetrahydrofuran, 1,3-dioxolane, 1 Ethers such as 1,4-dioxane and aromatics such as benzene, toluene and xylene can be used. These organic solvents can be used alone or in combination of two or more. Further, this organic solvent is used, for example, by adjusting the concentration of the nonvolatile component in the charge transport layer coating material in the range of 9% by weight to 12% by weight in order to make the charge transport layer 14 have a desired film thickness.

  The charge transport layer 14 is formed by the nozzle coat coating apparatus 40 shown in FIG. 4 using the charge transport layer coating material thus adjusted. Specifically, the aluminum tube 41 in which the charge generation layer 13 is formed on the aluminum tube 31 is mounted on the rotating unit 43 in a form supported by the rotation-free holding tool 42 and driven by the motor 44 to make a constant rotation. Rotate at several speeds. The rotation speed in this case is the coating rotation speed. The paint discharge nozzle 45 is moved in the longitudinal direction of the aluminum tube 41 by a ball screw 47 driven by a motor 46 while maintaining the same distance (1 mm or less) as the surface of the aluminum tube 41. The paint is quantitatively discharged from the pump 48 and discharged from the discharge nozzle 45 via the tube 49. The paint flies in a liquid state and reaches the surface of the aluminum tube 41, and the paint having a certain film thickness is applied to the surface of the rotating aluminum tube 41. After that, leveling is performed at a predetermined leveling rotational speed, and the process ends. The ball screw 50 is driven by a motor 51 and serves as a drive source for the pump 48. After the coating is completed, the paint is replenished to the pump 48 by switching the valve 52 and rotating the motor 51 in the reverse direction.

  Here, conditions required for the filler 14a and the binder resin 14b when manufacturing the electrophotographic photosensitive member will be described. Since centrifugal force is used in the present invention, the filler 14a must have a specific gravity heavier than that of the charge transport material in the coating material and the binder resin 14b. When the conductive support 11 is rotated at a predetermined peripheral speed or higher, a centrifugal force acts on the particles of each filler 14a, and a predetermined force or more acts outwardly in the charge transport material and the binder resin 14b. Each particle tries to move in the radial direction.

  However, since the binder resin 14b containing the charge transport material has a viscosity, the filler 14a acts as a resistance against movement. For this reason, the movement of the filler 14a does not proceed smoothly but moves while receiving resistance, and the density of the filler 14a inside the coating film gradually increases with the passage of coating time and leveling time on the surface layer side (outer periphery). Increases at the inner layer side (conductive support 11 side), and the distribution amount is biased in the thickness direction of the coating film.

  Thereby, even if the total amount of the whole filler 14a is small, since the density of the filler 14a is high on the surface layer, this high density portion is even in a state where the total amount is large and centrifugal force does not act. If the density is the same as the density of the filler 14a when distributed, the filler 14a in this portion has a sufficient wear resistance effect. That is, in terms of the total amount, even if the filler 14a is contained in a smaller amount than the amount of the conventional filler 14a, only the surface layer has a high density of the filler 14a effective in wear resistance. In addition, the amount of filler 14a is reduced on the inner layer side (conductive support 11 side) by the amount of uneven distribution. Thereby, an increase in residual potential can be suppressed. In this way, by applying a centrifugal force to the conductive support 11, it is possible to improve durability and prevent deterioration of image quality.

  The material and distribution of the filler 14a present in the surface layer is determined by the time during which the surface can be smoothed without film defects, the drying speed, the time until the coating is dried (until the volatilization is completed) Time). So leveling time is important. In addition to this, the peripheral speed that determines the magnitude of the centrifugal force, the added amount of filler 14a as the initial value of the distribution and its specific gravity (in other words, the type of substance), the binder resin 14b, the organic solvent, and the charge transport material It is necessary to consider resistance to movement (ie, the type of material, viscosity, etc.).

  If the leveling time is short, unevenness remains in the coating film, and if it is too long, the cost is high and drying is finished during leveling. If the drying rate is too high, drying will be completed in a short time. If it is too low, the formation of the coating film becomes difficult and it takes time to form the coating film. Further, if the rotation speed (rpm) is lower than a predetermined value, the followability of the filler 14a is poor, and the movement in the surface direction does not occur or even if it occurs, no distribution is formed before drying. If the number of rotations is higher than another predetermined value, the coating material is scattered by centrifugal force at the time of leveling and at least one of the rotations during coating, and the coating film cannot be formed or leveled. Furthermore, if the specific gravity of the filler 14a is smaller than that of the binder resin 14b and the charge transport material, the distribution cannot be formed by using centrifugal force. If the addition amount is less than the predetermined range, the amount of filler 14a necessary for the coating film is small. The body is not enough.

  Furthermore, the material, specific gravity, and addition amount of the filler 14a must not affect the residual potential. If the amount added is too much above the predetermined range, the increase in residual potential cannot be suppressed, and the effect of the conventional filler 14a having no distribution is not so different. Also, regarding the binder resin 14b, the organic solvent, and the charge transport material, if the type is a highly viscous material that resists the movement of the filler 14a, the filler 14a is dried before forming a distribution by centrifugal force. End up.

  Therefore, the material of the filler 14a, the leveling time, the drying speed, the peripheral speed, the specific gravity ratio of the filler 14a and the binder resin 14b, the addition amount, the binder resin 14b and the organic solvent, the kind of the charge transport material, and the like are influenced and are subtle. The applicability of coating and the distribution of the filler 14a are determined on balance. Therefore, if the distribution of the filler 14a inside the coating film is determined, the candidates for the material of the filler 14a and the material of the binder resin 14b are determined accordingly, and the leveling time, peripheral speed, specific gravity ratio The preferable range of the filler addition amount is determined. FIG. 5 is a tomographic image of the charge generation layer and the charge transport layer of the electrophotographic photosensitive member actually formed by applying centrifugal force. The filler is present at a high density on the surface layer side, and the density is low on the inner side. It can be seen that a clearly biased distribution is formed by the centrifugal force.

  As described above, the filler 14a includes alumina, beryllium oxide, zinc oxide, silica, and others, and the binder resin 14b includes resins such as polycarbonate, polyester, polysulfone, polyarylate, polymethyl methacrylate, and charge transport. As candidates, electron-donating oxazole compounds, oxadiazole compounds, pyrazoline compounds, hydrazone compounds, stilbene compounds, tetraphenylbutadiene compounds, biphenyl compounds, derivatives of these compounds, and the like are preferable. The charge transport material, the filler 14a, and the binder resin 14b are respectively selected from the above, and the composition ratio is 0.1 to 2 for the binder resin 14b, 0.1 to 2, and 0.1 for the charge transport material. 25-3 It may be selected so as to enclose. The combination of the filler 14a and the binder resin 14b such that the specific gravity ratio of the filler 14a with respect to the binder resin 14b is 2 to 4 provides an appropriate centrifugal force, thus realizing the followability of the filler 14a, resulting in wear resistance. It is possible to form an excellent coating film with respect to the property and residual potential.

  In addition, one or two or more of chlorinated hydrocarbons such as dichloromethane and chloroform, ethers such as tetrahydrofuran, aromatics such as benzene, toluene, and xylene are mixed to form an organic solvent, and a non-volatile component ( The weight concentration of the charge transport material and the binder resin 14b) with respect to the organic solvent is 12% or less. If this is higher than 12%, the drying is rapid, the particles of the filler 14a are not biased toward the surface layer side, and no distribution is formed. Further, the surface after coating becomes uneven, and the photoreceptor characteristics are deteriorated. However, if the concentration is lower than 9%, the ratio of the organic solvent is too high and it becomes difficult to dry, and leveling time after coating takes more than necessary. Therefore, the weight concentration of the non-volatile component with respect to the organic solvent is preferably 12% or less, and preferably 9% to 12% if possible. At this time, the followability of the filler 14a becomes excellent, a leveling time of 120 seconds or more necessary for forming a smooth coating film can be secured, and an appropriate drying speed can be obtained.

  And it is set as the combination of such a load transport material, the filler 14a and the binder resin 14b, and an organic solvent, and the peripheral speed at the time of leveling (peripheral speed of the conductive support after the spraying of the present invention) is 200 mm / s to 350 mm. / S, the movement of the filler 14a to the surface layer side can be realized with a favorable centrifugal force with good followability, and the distribution of the filler 14a on the surface layer is set to 50% or more in the region of 1/3 of the film thickness. be able to. In addition, if the peripheral speed is lower than 200 mm / s, the distribution of the filler 14a is not formed, and if the peripheral speed is higher than 350 mm / s, the paint is scattered by centrifugal force at the time of leveling and at least one rotation during application, A coating film cannot be formed. Further, the coating rotation speed and the peripheral speed during coating are most preferably about 150 mm / s to 225 mm / s (120 rpm to 180 rpm) in accordance with the leveling rotation speed and leveling peripheral speed during leveling.

  As described above, the electrophotographic photoreceptor according to the first exemplary embodiment of the present invention selects a combination of the filler 14a, the binder resin 14b, the charge transporting material, and the organic solvent that can form an appropriate centrifugal force and a high-quality coating film, and has a concentration. By adjusting, the leveling time and the peripheral speed are appropriately selected, and the distribution of the filler 14a is formed with an appropriate centrifugal force and resistance force, so that improvement in wear resistance and suppression of increase in residual potential can be realized at the same time. is there.

  Hereinafter, this invention is further demonstrated by Example 1 and Comparative Examples 1-8.

Example 1
<Conductive support>
As an electroconductive support, an aluminum (aluminum-magnesium-silicon alloy) cutting tube having an outer diameter of 24 mm, an inner diameter of 22.5 mm, and a length of 246 mm was removed with a degreasing detergent (Clean Through LC870 manufactured by Kao Corporation) and ion-exchanged water. What was washed was prepared.

<Undercoat layer>
First, polyamide resin with respect to a mixed solvent of 50 parts by weight of methanol (manufactured by Wako Pure Chemical Industries, Ltd.), 35 parts by weight of butanol (manufactured by Wako Pure Chemical Industries, Ltd.), and 15 parts by weight of benzyl alcohol (manufactured by Wako Pure Chemical Industries, Ltd.). (Toray Industries, Inc. CM-8000) A solution containing 5 parts by weight of titanium oxide (Ishihara Sangyo Co., Ltd. PT-401M, 70 nm) containing 5 parts by weight, and then adjusting the dispersion using a paint shaker did. This dispersion is spray coated on the conductive support mounted on the spray coating apparatus of FIG. 2 under the following conditions to form an undercoat layer 12 having a thickness of 1.0 μm at a drying temperature of 150 ° C. and a drying time of 30 minutes. did.

conditions:
・ Fine spray gun (manufactured by Nordson Co., Ltd.)
・ Rotation time after application is 10 seconds ・ Work speed 200Hz
・ Gun movement speed 12mm / sec ・ Gun-work distance 50mm
・ Atomization air pressure 0.15 MPa / cm ²
<Charge generation layer>
Next, after adding 1.2 parts by weight of titanyl phthalocyanine to a solution obtained by adding 0.8 parts by weight of butyral resin (Eslek BM-1 manufactured by Sekisui Chemical Co., Ltd.) to 98 parts by weight of 1,3-dioxolane The dispersion was adjusted using a paint shaker. This dispersion is dip-coated on the conductive support on which the undercoat layer is formed using the dip coating apparatus shown in FIG. 3, and a charge of 0.2 μm is generated at a drying temperature of 100 ° C. and a drying time of 20 minutes. Layer 13 was formed.

<Charge transport layer>
Subsequently, 40 parts by weight of the charge transport material and 60 parts by weight of the Z-type polycarbonate resin were dissolved in a mixed solvent of 380 parts by weight of tetrahydrofuran (manufactured by Wako Pure Chemical Industries, Ltd.) and 40 parts by weight of anisole (manufactured by Wako Pure Chemical Industries, Ltd.). 11 parts by weight of alumina is dispersed in the paint, and coating is performed with the nozzle coat coating apparatus of FIG. 4 under the conditions of a coating rotational speed of 120 rpm, a leveling rotational speed of 180 rpm (circumferential speed of 225 mm / s), and a leveling time of 120 s. The charge transport layer 14 having a thickness of 25 μm was formed at a drying temperature of 150 ° C. and a drying time of 40 minutes to complete the photoreceptor 10. The specific gravity of the filler 14a at this time is 3.25 with respect to the binder resin 14b.

conditions:
・ Discharge nozzle diameter 2.27mm
・ Nozzle to aluminum distance 0.24mm
・ Nozzle moving speed 272mm / min ・ Paint discharge rate 4.34CC / min <Evaluation>
Then, the obtained photoreceptor is mounted on a process cartridge of a printer DP-CL22 manufactured by Panasonic Communications Co., Ltd., and the filler distribution ratio in the 1/3 region from the surface of the film thickness, the surface potential after exposure, the halftone density evaluation, and the film The thickness reduction amount was evaluated. The results are shown in (Table 1). The filler distribution ratio in the 1/3 region from the surface of the film thickness is 55%, the surface potential after exposure is 149 V, the halftone density evaluation is normal, and the film scraping amount is 0.8 μm / 10k sheets (target 1 μm / 10k sheets or less) The printing durability was good.

(Comparative Example 1)
In Comparative Example 1, a photoconductor was prepared and evaluated in the same manner as in Example 1 except that the amount of alumina added in Example 1 was 0 part by weight. The results are shown in (Table 1). In this case, the film scraping amount showed a large value, and the printing durability was lowered because the distribution of alumina near the surface of the charge transport layer disappeared.

(Comparative Example 2)
In Comparative Example 2, a photoconductor was prepared and evaluated in the same manner as in Example 1 except that the leveling rotation speed in Example 1 was 120 rpm (circumferential speed 150 mm / s). The results are shown in (Table 1). Here, the filler distribution ratio in the 1/3 region from the surface of the film thickness was only 33%, the deviation of the alumina distribution was reduced, and the film scraping amount showed a large value. Since the leveling rotation speed has decreased, the centrifugal force effect is insufficient, the distribution of alumina in the vicinity of the surface of the charge transport layer is decreased, and the film scraping amount is considered to be increased.

(Comparative Example 3)
In Comparative Example 3, a photoconductor was prepared and evaluated in the same manner as in Example 1 except that the leveling rotation speed in Example 1 was 300 rpm (circumferential speed 375 mm / s). The results are shown in (Table 1). In this case, the paint was scattered and could not be applied.

(Comparative Example 4)
In Comparative Example 4, a photoconductor was prepared and evaluated in the same manner as in Example 1 except that the leveling time in Example 1 was 60 seconds. As shown in Table 1, the filler distribution ratio in the 1/3 region from the surface of the film thickness was 40%, the distribution amount of alumina was reduced, and the film scraping amount showed a large value. It is considered that since the leveling time is reduced, the time during which the centrifugal force acts is reduced, the distribution of alumina near the surface of the charge transport layer is reduced, and the amount of film scraping is increased.

(Comparative Example 5)
In Comparative Example 5, a photoconductor was prepared and evaluated in the same manner as in Example 1 except that the amount of alumina added was 3 parts by weight. As shown in (Table 1), the filler distribution ratio in the 1/3 region from the surface of the film thickness was only 33%, the distribution amount of alumina decreased, and the film scraping amount showed a large value. It is considered that since the amount of alumina added as a total amount decreased, the amount of alumina near the surface of the charge transport layer decreased and the amount of film scraping increased.

(Comparative Example 6)
In Comparative Example 6, a photoconductor was prepared in the same manner as in Example 1 except that the amount of alumina added was 22 parts by weight. As shown in (Table 1), the filler distribution ratio in the 1/3 region from the surface of the film thickness is 50%, and the distribution amount of alumina is suitable, but the surface potential after exposure increases considerably and the halftone density decreases. did. It is considered that since the amount of alumina added is too large, the surface potential after exposure deteriorates and the halftone density decreases.

  Subsequently, a photoconductor was prepared and evaluated in the same manner as in Example 1 except that the type of filler in Example 1 and thus the specific gravity ratio was changed. The results are shown in (Table 2).

(Comparative Example 7)
In Comparative Example 7, a photoconductor was prepared in the same manner as in Example 1 except that the filler alumina in Example 1 was changed to silica. In this case, the specific gravity ratio was 2, and the centrifugal force was slightly smaller than that of Example 1, but the filler distribution ratio in the 1/3 region from the surface of the film thickness could be 50%.

(Comparative Example 8)
In Comparative Example 7, a photoconductor was prepared in the same manner as in Example 1 except that the filler alumina in Example 1 was changed to zinc oxide. In this case, the specific gravity ratio was 4, the centrifugal force was larger than in Example 1 and Comparative Example 7, and the filler distribution ratio in the 1/3 region from the surface of the film thickness could be 60%.

  As described above, the electrophotographic photosensitive member of the first embodiment is adjusted to a proper level by adjusting the leveling time and the peripheral speed by adjusting the concentration and the rotation speed by combining the filler, the binder resin, the charge transport material, and the organic solvent, and adjusting the rotation speed. A distribution is formed in the filler in the coating film by force and resistance, and improvement of wear resistance and suppression of residual potential can be realized at the same time.

  The present invention improves the wear resistance of the photoreceptor of the electrophotographic apparatus without degrading the image quality, thereby achieving a long life, thereby extending the replacement interval of the photoreceptor or process cartridge as a consumable, It is useful as an electrophotographic photosensitive member capable of obtaining the effect of reducing running costs and a method for producing the same.

Sectional drawing which shows typically the structure of the electrophotographic photoreceptor in Embodiment 1 of this invention. Schematic which shows the structure of the spray coating apparatus used with the manufacturing method of the electrophotographic photoreceptor in Embodiment 1 of this invention. Schematic which shows the structure of the dip coating apparatus for charge generation layer formation used with the manufacturing method of the electrophotographic photoreceptor in Embodiment 1 of this invention. Schematic which shows the structure of the nozzle coat coating apparatus for charge transport layer formation used with the manufacturing method of the electrophotographic photoreceptor in Embodiment 1 of this invention. The figure which shows the tomogram of the electrophotographic photoreceptor in Embodiment 1 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Electrophotographic photoreceptor 11 Conductive support body 12 Undercoat layer 13 Charge generation layer 14 Charge transport layer 14a Filler 14b Binder resin 20 Spray coating apparatus 21, 22 Support fixing jig 23 Spray gun 24 Coating liquid 30 Charge generation layer formation Immersion coating device 31 Aluminum tube 32 Movable part with fixed jig 33 Charge generation layer coating 34 Pot 35 Circulation pump 36 Filter unit 37 Ball screw 38 Motor 40 Charge transport layer forming nozzle coat coating device 41 Aluminum tube 42 Holding Tool 43 Rotating Unit 44 Motor 45 Discharge Nozzle 46 Motor 47 Mold Screw 48 Pump 49 Tube 50 Ball Screw 51 Motor 52 Valve 53 Pot

Claims (18)

A cylindrical conductive support; and a cylindrical photosensitive layer formed on the conductive support. The photosensitive layer is a coating in which a filler and a charge transport material are dispersed in a binder resin solution. An electrophotographic photosensitive member having a structure in which a working solution is applied by spraying onto the conductive support,
The electrophotographic photoreceptor, wherein the filler has a specific gravity heavier than that of the charge transport material and the binder resin, and is distributed more on the surface side of the photosensitive layer. A cylindrical conductive support, a charge generation layer stacked on the conductive support, and a charge transport layer stacked on the charge generation layer, the charge transport layer transporting a filler and a charge An electrophotographic photosensitive member having a structure in which a coating liquid in which a substance is dispersed in a binder resin solution is sprayed onto the conductive support and applied.
The electrophotographic photoreceptor, wherein the filler has a specific gravity heavier than that of the charge transport material and the binder resin, and is distributed more on the surface side of the charge transport layer. The electrophotographic photosensitive member according to claim 1, wherein a weight ratio of the filler is 5% or more and 20% or less with respect to the nonvolatile component. The electrophotographic photosensitive member according to claim 1, wherein the specific gravity of the filler is 2 to 4 times that of the binder resin. 3. The electrophotographic photosensitive member according to claim 2, wherein a distribution amount of the filler is 50% or more in a range of 1/3 depth from the surface of the charge transport layer. A cylindrical conductive support; and a cylindrical photosensitive layer formed on the conductive support. The photosensitive layer is a coating in which a filler and a charge transport material are dispersed in a binder resin solution. An electrophotographic photosensitive member having a structure in which a working solution is applied by spraying onto the conductive support,
The filler has a specific gravity heavier than that of the charge transport material and the binder resin, and is distributed more on the surface side of the photosensitive layer, and the weight ratio of the filler is 5% or more and 20% or less with respect to the nonvolatile component, The electrophotographic photosensitive member is characterized in that the filler has a specific gravity of 2 to 4 times that of the binder resin. A cylindrical conductive support, a charge generation layer stacked on the conductive support, and a charge transport layer stacked on the charge generation layer, the charge transport layer transporting a filler and a charge An electrophotographic photosensitive member having a structure in which a coating liquid in which a substance is dispersed in a binder resin solution is sprayed onto the conductive support and applied.
The filler has a specific gravity heavier than that of the charge transport material and the binder resin, and is distributed more on the surface side of the charge transport layer, and the weight ratio of the filler is 5% or more and 20% or less with respect to the nonvolatile component. The filler has a specific gravity of not less than 2 and not more than 4 times that of the binder resin, and the distribution amount of the filler is not less than 50% within a depth of 1/3 of the surface of the charge transport layer. An electrophotographic photoreceptor characterized by the above. A charge transport material and a filler having a specific gravity heavier than that of the binder resin are made together with the charge transport material to form a coating solution in which the binder resin is dissolved, and a cylindrical conductive support is supported in the axial direction. The conductive support is rotated at a predetermined peripheral speed or more around the axis of the conductive support, and the coating liquid is sprayed onto the conductive support to form a photosensitive layer. After the spraying is completed, the conductive support is The leveling is performed by rotating at a peripheral speed or higher, and the distribution amount of the filler in the photosensitive layer is increased on the surface side of the photosensitive layer by centrifugal force during at least one of rotation during coating and leveling. A method for producing an electrophotographic photoreceptor. A cylindrical conductive support with a charge generation layer formed on the surface of a charge transport material and a filler having a specific gravity heavier than that of the binder resin, together with the charge transport material, is dispersed in the binder resin solution. The body is supported in the axial direction, rotated about a shaft of the conductive support at a predetermined peripheral speed or more, and the coating liquid is sprayed onto the conductive support to form a charge transport layer and sprayed. After completion, the conductive support is rotated at a predetermined peripheral speed or higher to perform leveling, and the amount of the filler in the charge transport layer is distributed by the centrifugal force during the rotation of at least one of coating and leveling. A method for producing an electrophotographic photoreceptor, wherein the size is increased on the surface side of the layer. 10. The method for producing an electrophotographic photosensitive member according to claim 8, wherein a peripheral speed of the conductive support after the spraying is set to 200 mm / s or more and 350 mm / s or less. 10. The method for producing an electrophotographic photosensitive member according to claim 8, wherein the conductive support is further rotated for 120 seconds or more after the spraying is completed. 10. The method for producing an electrophotographic photosensitive member according to claim 8, wherein a weight ratio of the filler is 5% or more and 20% or less with respect to the nonvolatile component. 10. The method for producing an electrophotographic photosensitive member according to claim 8, wherein the specific gravity of the filler is 2 to 4 times that of the binder resin. 10. The method for producing an electrophotographic photosensitive member according to claim 9, wherein the distribution of the filler is 50% or more in a depth range of 1/3 from the surface of the charge transport layer. A charge transport material and a filler having a specific gravity heavier than that of the binder resin are made together with the charge transport material to form a coating solution in which the binder resin is dissolved, and a cylindrical conductive support is supported in the axial direction. The conductive support is rotated at a predetermined peripheral speed or more around the axis of the conductive support, and the coating liquid is sprayed onto the conductive support to form a photosensitive layer. After the spraying is completed, the conductive support is Electrophotographic photosensitivity in which leveling is performed by rotating at a peripheral speed or higher for a predetermined time, and the distribution amount of the filler in the photosensitive layer is increased on the surface side of the photosensitive layer by centrifugal force when rotating at least one of coating and leveling. A method for manufacturing a body,
When making the coating liquid, the filler weight ratio is 5% or more and 20% or less with respect to the non-volatile component, and the specific gravity of the filler is 2 times or more and 4 times or less with respect to the binder resin, The peripheral speed of the conductive support after the spraying is finished is set to 200 mm / s or more and 350 mm / s or less, and the conductive support is rotated for 120 seconds or more after the spraying is finished. A method for producing a photographic photoreceptor. 16. The method for producing an electrophotographic photosensitive member according to claim 15, wherein the weight concentration of the non-volatile component to the organic solvent is 9% to 12%. A cylindrical conductive support with a charge generation layer formed on the surface of a charge transport material and a filler having a specific gravity heavier than that of the binder resin, together with the charge transport material, is dispersed in the binder resin solution. The body is supported in the axial direction, rotated about a shaft of the conductive support at a predetermined peripheral speed or more, and the coating liquid is sprayed onto the conductive support to form a charge transport layer and sprayed. After completion, the conductive support is rotated for a predetermined time at a predetermined peripheral speed or more to perform leveling, and the distribution amount of the filler in the charge transport layer is determined by centrifugal force during at least one of rotation during coating and leveling. A method for producing an electrophotographic photoreceptor that is enlarged on the surface side of a charge transport layer,
When making the coating liquid, the filler weight ratio is 5% or more and 20% or less with respect to the non-volatile component, and the specific gravity of the filler is 2 times or more and 4 times or less with respect to the binder resin, The peripheral speed of the conductive support after the spraying is finished is set to 200 mm / s or more and 350 mm / s or less, and the conductive support is rotated for 120 seconds or more after the spraying is finished. A method for producing a photographic photoreceptor. 18. The method for producing an electrophotographic photosensitive member according to claim 17, wherein the weight concentration of the non-volatile component to the organic solvent is 9% to 12%.