JP2000221708A - Manufacturing method of electrophotographic photoreceptor - Google Patents

Abstract

(57) Abstract: An electrophotographic photoreceptor used in an electrophotographic image forming apparatus or the like by a dip coating method, which has a highly uniform film thickness and can form a good image. Is to provide a method of manufacturing the same. SOLUTION: In producing an electrophotographic photoreceptor by forming a functional resin layer on a substrate by a dip coating method, the substrate is immersed in a functional resin liquid, and then at a predetermined position from the immersion upper end of the substrate. After the primary immersion treatment of pulling up and immersing again, in the same manner as in the case of repeatedly performing the pulling-immersion operation, after performing the secondary immersion treatment of performing multiple immersions in which the raising width at the time of the lifting operation is reduced stepwise, the resin liquid This is a method for producing an electrophotographic photoreceptor, which comprises lifting a substrate from a substrate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an electrophotographic photoreceptor, and more particularly, to a method for manufacturing a photoreceptor obtained by forming a functional resin layer on a substrate by a dip coating method. The present invention relates to a method for manufacturing an electrophotographic photoconductor in which a high-quality image is formed by forming a uniform thickness.

[0002]

2. Description of the Related Art Conventionally, a drum type or belt type photoreceptor has been used in an electrophotographic image forming apparatus such as a copying machine, a printer and a facsimile. In order to manufacture these photoconductors, a photoconductor substrate having a conductive surface is usually immersed in a resin solution comprising a photoconductive material and a binder resin by a dip coating method, and a photoconductor layer is formed on the substrate surface. Is generally adopted. In the dip coating method, for example, a cylindrical drum-shaped substrate is immersed in the resin liquid, and then the substrate is pulled up at a predetermined speed in the axial direction, and the resin layer applied on the surface is dried and solidified. Then, a photosensitive layer is formed on the surface of the substrate to obtain a photoconductor for electrophotography. Usually, since a plurality of functional layers such as an undercoat layer, a charge generation layer, and a charge transport layer are formed by lamination,
In the dip coating described above, the coating is performed a plurality of times by immersing in the respective functional resin liquids.

[0003] Therefore, the uniformity of each coating film to be laminated and the uniform thickness of the coating film affect the quality of the photoreceptor, such as potential unevenness during charging and printing unevenness during development. In this dip coating method, how to form a coating film having a uniform thickness has conventionally been a very important manufacturing problem. That is, the resin is attached to the surface by immersing the substrate in a resin solution, and when the substrate is pulled up, the resin attached to the substrate surface is subjected to dip coating under the condition of dripping in the longitudinal direction. Has traditionally been
The film thickness applied to the substrate is thin at the top in the vertical direction during immersion,
It is difficult to prevent the lower portion from gradually becoming thicker. Therefore, it is generally very difficult to make the film thickness uniform by this dip coating method.

[0004] In view of the above, various methods for forming a uniform coating film have been conventionally proposed. For example, JP-A-59-80364 discloses a method in which a substrate is immersed in a coating material and then immersed in the coating. A dip coating method is described in which the base is pulled up at a predetermined speed, immersed again, and then pulled up at a predetermined speed. However, with this method,
In particular, as a solvent for the resin liquid, for example, a solvent having a high boiling point and a low evaporation rate, such as generally used tetrahydrofuran (THF), tends to cause uneven drying and solidification,
It tends to be difficult to form a uniform coating, and even when a high-viscosity solvent is used, it tends to be difficult to form a uniform coating similarly.

Japanese Patent Application Laid-Open No. Hei 2-21047 discloses that after a substrate is immersed in a resin solution, a part of the substrate is pulled up at a predetermined speed and immersed again before the coating film is dried. It is described how to go and then raise completely. This method is basically the same as the proposal described in the above-mentioned gazette, and particularly, in accordance with the performance of the developing unit of a copying machine, a printer, etc., which has been improved in performance and function as in recent years, the quality of the image is further improved. However, in order to sufficiently achieve the photoreceptor and the like, even the proposed method cannot achieve satisfactory coating uniformity for improving the photoreceptor quality.

[0006]

As described above, it is impossible to obtain a photosensitive member having a highly uniform coating thickness by the conventional dip coating method. Further, in particular, a resin solution using a solvent having a high boiling point and a high viscosity has not yet been provided with a method for sufficiently achieving the problem of uniform coating thickness.

Further, halogen solvents such as dichloromethane (MDC), which have been conventionally used as a good solvent for a resin solution, have been regarded as a problem due to their effects on the human body due to regression cycles of the environment and nature. As a substitute solvent, as described above, when a solvent having a high boiling point and not easily scattered into the atmosphere, for example, a solvent such as THF is used, the above-described various problems are caused by the conventional dip coating method. Is difficult to meet.

[0008] Under such circumstances, an object of the present invention is a dip coating method for solving the problem of uniformity of the above-mentioned problems, and in particular, there has been a demand for high performance and high functionality as in recent years. In copiers, printers, etc., it is possible to achieve good coating uniformity that can sufficiently achieve good image quality, etc., in addition to the performance of the developing section, and to use a resin solution that uses a high boiling point solvent. It is another object of the present invention to provide a method for producing a photoreceptor by a dip coating method which can sufficiently cope with the problem.

[0009]

Means for Solving the Problems In view of the above-mentioned problems, the present inventors have proposed an immersion coating method for producing an electrophotographic photoreceptor by immersing and lifting a substrate in a coating resin solution. Through further study, the present inventors have found an immersion-pull-up operation method for solving the above-mentioned problem relating to uniformity, and have completed the present invention.

That is, according to the present invention, when a functional resin layer is formed on a substrate by a dip coating method to manufacture an electrophotographic photosensitive member, the substrate is immersed in a functional resin solution, and then the upper end of the substrate is immersed. After the primary immersion treatment of pulling up to a predetermined position and immersing again, in the same manner, when repeatedly performing the pulling-immersion operation, a secondary immersion process of performing multiple immersion to gradually reduce the pulling width at the time of the lifting operation Thereafter, there is provided a method for producing an electrophotographic photoreceptor, wherein the substrate is lifted from the resin liquid.

According to the present invention, an example of a method for manufacturing a photoreceptor by the dip coating method includes a manufacturing process as shown in FIG. As is clear from the process conceptual diagram based on the block cross-sectional view, the process from the block is the above-described primary immersion process, and then the process from the block performs the pulling-immersion operation many times (or in multiple stages). 2
This is the next immersion process. In the present invention, when performing the latter secondary immersion treatment step, the withdrawal widths (H1, H2) to be performed many times are set as shown in FIG. The present invention is characterized in that the width (H0) is shorter than the width (H0 <H1 <H2 <H3}).

Thus, as is apparent from Example 1 (see the graph shown in FIG. 2) described later, the upper end in the immersion longitudinal direction, which is a drawback of this immersion coating method, which cannot be obtained by the conventional method, is thin. It can be clearly seen that the nonuniformity of the film thickness is eliminated. In addition, as is apparent from the graphs (a) and (b) shown in FIG. 1, as a function and effect based on the step of the secondary immersion treatment performed a number of times (or in multiple stages) of the present invention, it is formed on the substrate surface. It can be clearly seen that the film thickness is made uniform.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As described above, according to the present invention, in the dip coating method, the secondary dip treatment is performed in combination with the primary dip treatment, which has heretofore been a drawback of this method. Thus, it was possible to provide a method of manufacturing a photoreceptor capable of eliminating non-uniformity in film thickness caused in a longitudinal direction of immersion of a substrate immersed in a coating resin solution.

Hereinafter, an embodiment of a method of manufacturing a photoreceptor used for forming an electrophotographic image according to the present invention will be described with reference to FIGS.

In the present invention, the shape (or shape) of the substrate (or support) of the photoreceptor may be an endless belt shape,
Sheet-, web-, and cylindrical-drum types are not particularly limited, and can be appropriately subjected to the above-described dip coating method. Therefore, in the examples described later, a cylindrical conductive substrate made of aluminum is used, but the present invention is not particularly limited to this, and usually a cylindrical photoconductor is mainly used.

Therefore, as shown in FIG. 1, the step from the block is the step of the primary immersion treatment described above, and in the present invention, preferably, the substrate is completely immersed in the coating resin liquid in the primary immersion treatment step. In the primary immersion treatment step of (block) -pulling (block) operation, preferably, the following formula (1), H0≤L / 2------------(1) H0: the distance of the part where the substrate is pulled up from the coating resin liquid at the time of the primary immersion treatment, and L: the length of the substrate. Is preferably processed to satisfy the following. here,
The pulling width of H0 varies depending on the kind of the resin in the coating resin liquid and, in particular, the dripping condition of the resin liquid due to its viscosity. ) And it is preferable that the above expression (1) is satisfied.

Further, as shown in FIG. 1, after the above-mentioned primary immersion treatment step, as described above, the step from the block is performed a number of times (or in multiple stages) in the present invention.
Is a secondary immersion process step in which the operation of lifting and immersion is repeatedly performed. The example shown in FIG. 1 is an embodiment performed in two stages, and the pull-up widths H1 and H2 shown in the block (H1) and the block (H2) are sequentially shortened (H0 <H
1 <H2) It is repeated. In this process, the lifting width (H1) of the block is applied to cover the sagged portion that could not be covered by the block, and the lifting width (H2) of the block is applied to cover the sagged portion that could not be covered by the block. It is.

[0018] By carrying out in this manner, the coating film is uniformly applied, and the whole is pulled up by the block to form the coating film. Many pulls here-
The repetition operation of the immersion is performed while visually observing whether the dripping condition of the resin is uniform and the coating thickness is uniform, and furthermore, the pulling width is shortened and the treatment is performed in multiple stages. Therefore, in the present invention, the number of repetitions is preferably at least two or more.

Further, by the dip coating method according to the present invention as described above, as will be apparent from the examples described later,
As a film thickness to be formed on the substrate surface, 0.5 ~ 100μ
Within the range of m, a photoconductor having a uniform film thickness can be obtained.

In the present invention, a plurality of coating films such as at least a charge generation layer and a charge transport layer can be formed on the substrate surface by the dip coating method of the present invention described above. In addition, in addition to the photosensitive layer, an undercoat layer, a protective layer, a conductive layer, etc.
The dip coating method of the present invention can be appropriately used for forming these coating layers, since the layers are formed in combination as needed.

In the present invention, the solvent used for the coating resin liquid is not particularly limited to a kind thereof, but preferably, a solvent having a viscosity in the range of 50 to 1000 mPa · s is suitably used. It can be suitably used. If the viscosity is less than the lower limit, the viscosity of the coating resin liquid is too low, the resin sagging is too large, making it difficult to form a coating film, which is not preferable. And it is difficult to form a uniform coating film.

In the present invention, these solvents are replaced with halogen-based solvents such as dichloromethane (MDC) which have been generally used in the past. As a solvent which has a high boiling point and is not easily scattered in the air due to the influence on the human body or the like due to the regression cycle in nature, for example, a solvent such as THF can be suitably used.

Therefore, as the photoconductive material used for the above-mentioned charge generation layer, conventionally known phthalocyanine-based, quinacridone-based, azoxybenzene-based, cyanine-based, azo-based, pyrylium-based, indico-based, perylene-based, and the like.
Thiapyrylium-based, squaric-oxygen-based, polycyclic quinone-based and the like can be mentioned. Examples of the charge transport material used in the charge transport layer include conventionally known hydrazone compounds, poly-N-vinylcarbazole, fluorene, pyrazoline compounds, oxadiazole, indole compounds, carbazole compounds, and anthracene. . As binder resins used for these, polycarbonate, methacrylic resin, epoxy resin, polyamide, polyacrylamide, polyurethane,
Such as basic resins, butyral resins, polyvinyl chloride,
Examples thereof include acidic resins such as polyvinyl ketone, polystyrene, polyester, phenolic resin, and phenoxy resin. These resins have dispersion stability, viscosity, adhesiveness, hardness, and abrasion resistance as a coating resin liquid. It can be appropriately selected in consideration of electrical characteristics such as charging property and sensitivity of the photoreceptor.

[0024]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited thereto.

Example 1 A charge transport material and a polycarbonate resin dissolved in THF having a viscosity of 200 mPa · s
Was prepared. A cylindrical substrate made of aluminum and having a diameter of 30 mm and a length (L) of 340 mm is immersed in this resin liquid, and then, as a primary immersion treatment, the substrate is pulled up so that its upper pulling width (H0) becomes 100 mm. Then, it was immersed again. Next, as a secondary immersion treatment, the upper pull-up width (H1) is raised to 60 mm, and then dipped again. Subsequently, the upper pull-up width (H2) is further raised to 20 mm.
Multiple treatments were performed in two stages of immersion again. Next, the substrate is completely lifted from the resin solution and dried sufficiently.
The film thickness of the solidified resin-coated substrate was measured by an eddy current film thickness meter manufactured by Fischer, and the results are shown in FIG. 2 (graphs in the figure). The graph shown in FIG.
The horizontal axis represents the film thickness (μm) of the photoconductor at that position with respect to the distance [W (mm)] from the upper end in the vertical direction of the substrate during dip coating.

As is apparent from FIG.
The photoreceptor obtained by performing the next immersion processing step and the second immersion processing step, by combining these steps,
It can be seen that a good photoreceptor having a uniform film thickness can be obtained. In addition, even if the solvent of the resin liquid has a high boiling point, such as THF, and easily causes resin sagging during dip coating, it can be seen that the coating is performed uniformly.

(Reference Example) In the dip coating method of the present invention carried out in Example 1, in order to clarify the effect of the present invention of multiple treatments by the secondary immersion step, the primary immersion step was performed as follows.
When the base is pulled up so that the upper pulling width (H0) becomes 100 mm width and then immersed again,
In order to perform one secondary immersion step, the upper lifting width (H
1) The resin-coated substrate was prepared in the same manner as in Example 1 except that the substrate was pulled up to 60 mm and then immersed again, and the film thickness was measured in the same manner. The results are shown in graph (a) and graph (b) of FIG.
Here, in Example 1, as a comparative example, after the substrate was immersed in the resin solution, the substrate was pulled up as it was without performing the primary immersion step of the present invention, and the substrate was sufficiently dried and solidified. The film thickness was measured, and the result was compared with Comparative Example 1.
FIG. 2 (the graph with a square in the figure). Thus, as is clear from FIG. 2, the effect of making the film thickness uniform by performing the secondary immersion step according to the present invention many times (or in multiple steps) can be clearly understood.

Example 2 Example 1 was repeated except that a charge transport material and a polycarbonate resin were dissolved in THF to obtain a coating resin liquid having a viscosity of 50 mPa · s. The thickness of the resin-coated substrate obtained by performing the same primary immersion step and the secondary immersion step was measured in the same manner, and the results are shown in Table 1 as Example 2. Here, Table 1 shows the results of processing performed in the same manner as in Comparative Example 1 as Comparative Example 2. Thus, as is clear from Table 1, even in the case of a low-viscosity solvent, if the film thickness is 0.5 μm or more, the part to be pulled up in the primary immersion treatment step is the above formula (1) (H0 ≦ L / 2). It can be seen that the film becomes uniform by performing the immersion many times (or in multiple stages) in the secondary immersion step.

Example 3 Example 1 was the same as Example 1 except that a charge transport material and a polycarbonate resin were dissolved in THF and the viscosity was 1000 mPa · s. The thickness of the resin-coated substrate obtained by performing the same primary immersion step and secondary immersion step was measured in the same manner, and the results are shown in Table 1 as Example 3. Here, the result treated in the same manner as in Comparative Example 1 was shown in Table 1 as Comparative Example 3. Thus, as is clear from Table 1, even in the case of a high-viscosity solvent, if the film thickness is 100 μm or less, the part to be pulled up in the primary immersion step is the above formula (1) (H0
≦ L / 2), and the film is made uniform by performing the immersion many times (or in multiple stages) in the secondary immersion step.

[0030]

[Table 1]

[0031]

According to the present invention, in the dip coating method,
By performing the secondary immersion treatment in combination with the primary immersion treatment, the non-uniformity of the film thickness occurring in the longitudinal direction of immersion of the substrate immersed in the coating resin liquid, which has been a drawback of this method, is conventionally effective. Thus, it is possible to provide a method for manufacturing a photoconductor in which a photoconductor having a uniform thickness can be obtained.
In addition, by performing the pulling-dipping operation in the secondary immersion process multiple times (multi-stage), and by repeatedly repeating the pulling width in a short time, the film thickness can be made highly uniform, and Since the film thickness at the end can be made uniform, the upper end in the vertical direction during immersion does not become a dead space (a surplus surface that does not need to be used) as in the past,
As a result, the photoreceptor can be made more compact and cost can be reduced as compared with the conventional method.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram illustrating a manufacturing process of an electrophotographic photosensitive member by a dip coating method according to the present invention. In the figures, L: the length of the substrate in the axial direction; H0: the width of pulling up the substrate in the primary immersion process; and H1, H2: the respective substrates during multiple immersion in the secondary immersion process. Indicates the width of the pull-up.

FIG. 2 is a graph showing a film thickness distribution (film thickness uniformity) of a functional resin layer formed on a substrate surface of a photoreceptor manufactured in an example of the present invention, and the horizontal axis represents the time of dip coating Is the distance [W (mm)] from the upper end in the vertical direction of the substrate, and the vertical axis represents the film thickness (μm) at that portion of the photoconductor. In the drawings, the symbol ◆ indicates an example, and the symbol □ indicates a comparative example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Immersion coating tank 2 Coating resin liquid 3 Substrate 4 Substrate support jig

Claims (7)

[Claims] In producing a photoreceptor for electrophotography by forming a functional resin layer on a substrate by a dip coating method, the substrate is immersed in a functional resin solution, and then a predetermined amount is immersed from the immersion upper end of the substrate. After the primary immersion treatment in which the position is pulled up and immersed again, after the same immersion operation is repeated, the secondary immersion treatment in which the immersion operation is repeated multiple times to gradually reduce the lifting width during the lifting operation is performed. A method for manufacturing an electrophotographic photoreceptor, wherein a substrate is pulled up from the resin liquid. 2. The method according to claim 1, wherein said substrate is a cylindrical conductive support. 3. A method for producing an electrophotographic photoreceptor in which at least a charge generation layer and a charge transport layer are laminated on the substrate, wherein a charge transport layer is formed on the substrate on which the charge generation layer has been formed in advance. 2. The method according to claim 1, wherein the resin liquid is a resin liquid for forming the charge transport layer. 4. In the primary immersion treatment, a part to be pulled up is determined by the following formula (1): H0 ≦ L / 2 (1) where H0 is a resin at the time of the primary immersion treatment. It is the distance of the part where the substrate is pulled up from the liquid, and L is the length of the substrate. The method for producing an electrophotographic photoreceptor according to claim 1, wherein the relationship represented by the following formula is satisfied. 5. The method for producing an electrophotographic photoreceptor according to claim 1, wherein a film thickness of the resin formed by a dip coating method is in a range of 0.5 to 100 μm. 6. The viscosity of a solvent used for the resin liquid is as follows:
2. The method for producing an electrophotographic photosensitive member according to claim 1, wherein the pressure is 50 to 1000 mPa · s. 7. The method according to claim 1, wherein the solvent used in the resin liquid is tetrahydrofuran or an organic solvent containing tetrahydrofuran.