JPH0895275A - Support for electrophotographic photoreceptor and electrophotographic photoreceptor using the support - Google Patents

Abstract

(57) [Summary] (Modified) [Purpose] An electrophotographic photoconductor in which a photosensitive layer formed on a support for an electrophotographic photoconductor has a uniform film thickness over the entire surface of the support by an extremely simple method. Provided is a support and an electrophotographic photosensitive member including the support. As a result, the size of the photoconductor can be reduced, and the size of the electrophotographic copying machine can be reduced. In a cylindrical electrophotographic photosensitive member support used for forming an electrophotographic photosensitive layer by a dip coating method, an outer diameter in the vicinity of an end of the support, which is above the dip coating direction, is It is characterized in that it gradually decreases from the center side of the support to the end side of the support. Further, in the cylindrical electrophotographic photosensitive member having an outer diameter on the end side deviating from the gradually decreasing region larger than the minimum outer diameter of the gradually decreasing region, until reaching a region having the minimum outer diameter of the gradually decreasing region of the support. Is covered with the electrophotographic photosensitive layer.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a support for an electrophotographic photosensitive member used for forming an electrophotographic photosensitive layer by a dip coating method, and an electrophotographic photosensitive layer on the support by a dip coating method. The present invention relates to the formed electrophotographic photosensitive member.

[0002]

2. Description of the Related Art Generally, an electrophotographic photosensitive member is formed by forming an inorganic photosensitive layer on a conductive support by means such as vapor deposition, or by coating an organic photosensitive layer forming liquid on the conductive support and drying it. Is manufactured by. In particular, organic electrophotographic photoreceptors have been widely used in recent years because of their advantages such as ease of production, and a method called a dip coating method has become the mainstream as a means for production. The dip coating method is to immerse a conductive support in a photosensitive layer forming liquid and then pull up the support.
Then, the electrophotographic photosensitive layer is formed on the support by removing the solvent of the photosensitive layer forming liquid by natural drying or forced drying. When such a dip coating method is carried out, liquid drop of the photosensitive layer forming liquid occurs at the upper end of the support of the electrophotographic photosensitive member support, which is located on the pulling up side of the support. When the sagging liquid spreads to the image forming portion of the electrophotographic photosensitive member, the film thickness of the photosensitive layer becomes thin in the sagging portion after the drying step. as a result,
A region where the thickness of the photosensitive layer is thin is different from the other regions in charging property, so that a desired image cannot be formed, and the commercial value is lost as an electrophotographic photoreceptor. Several methods have been proposed as means for solving the problems in the above-mentioned dip coating method. For example, JP-A-59-12049 and JP-A-59-1748.
No. 44 and JP-A-62-050836, the concentration of the solvent vapor in the upper part of the bath is reduced or the support is reduced during the step of dipping the electrophotographic photoreceptor support in the photosensitive layer forming liquid bath. It has been proposed that the film thickness of the photosensitive layer formed on the support be made uniform both in the upper part and the lower part by controlling the atmospheric temperature when the body is pulled up from the bath. Also,
For the same purpose, Japanese Patent Laid-Open No. 59-080364 proposes to coat the upper part of the electrophotographic photosensitive member support twice. However, such a conventional method inevitably increases the size and complexity of the device, leading to an increase in cost per product.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems and to provide a support for an electrophotographic photoreceptor by a very simple method without increasing the size and complexity of a coating tank. The photosensitive layer formed on the body provides an electrophotographic photoreceptor support having a uniform film thickness over the entire surface of the support. Another object of the present invention is to provide an electrophotographic photosensitive member including the support. By providing such a support for an electrophotographic photosensitive member and an electrophotographic photosensitive member, the photosensitive member can be downsized, and further, the electrophotographic copying machine can be downsized.

[0004]

The present invention relates to a cylindrical support for an electrophotographic photosensitive member, which is used for forming an electrophotographic photosensitive layer by a dip coating method, and is located above the dip coating direction. The outer diameter in the vicinity of the end portion of the support gradually decreases from the support center side toward the support end portion side, or the outer diameter on the end side deviating from the gradually decreasing region is smaller than the minimum outer diameter of the gradually decreasing region. The support for an electrophotographic photosensitive member is also characterized by being large. Further, the outer diameter in the vicinity of the end of the support, which is on the upper side with respect to the dip coating direction, has a region that gradually decreases from the support center side toward the support end part side, and from the gradually decreasing region. In an electrophotographic photosensitive member having an electrophotographic photosensitive layer provided on a cylindrical support for an electrophotographic photosensitive member, the outer diameter of the detached end side is larger than the minimum outer diameter of the gradually decreasing region, the minimum of the gradually decreasing region of the support. The electrophotographic photosensitive member is characterized in that a portion up to a region having an outer diameter is covered with the electrophotographic photosensitive layer. The material of the electrophotographic photosensitive member support used in the present invention is generally aluminum, an aluminum alloy or the like, and the shape thereof is generally a cylindrical shape such as a cylinder. The surface of the support is subjected to surface processing by cutting or grinding to smooth the surface, or to improve the adhesiveness between the photosensitive layer and the support, and to prevent moire fringes by exposure to laser light, so that the surface is appropriately roughened. When this support is used as it is, it is dipped in a coating tank of a photosensitive layer forming liquid so that the axial direction of the support cylinder is vertical, and coating is performed, whereby a photosensitive layer is formed near the upper end of the support cylinder. Sagging of the liquid will occur. This sagging occurs remarkably when the amount of the photosensitive layer forming liquid is to be increased, for example, when the charge transport layer of the laminated organic electrophotographic photosensitive member having a large amount of adhesion is formed.

When the sagging during dip coating reaches the planned image area of the support, the film thickness of the photosensitive layer formed in that area becomes thin, and the potential due to charging does not reach the desired level. However, the obtained image is not satisfactory such as background stain. In order to solve this, a slightly larger support cylinder may be used for sagging, but
With such a support, the photoconductor naturally becomes large, and as a result, the copying apparatus also becomes large. On the other hand, using the electrophotographic photoreceptor support of the present invention, the support is immersed in a coating tank of the photosensitive layer forming liquid so that the axial direction of the support cylinder is vertical, and the end of the support is The outer diameter of the region is soaked with the region gradually decreasing from the support center side toward the support end side as the upper side, and then the support is pulled up to apply the photosensitive layer forming liquid, Since the coating liquid is held obliquely as compared with the upper end portion of the conventional support, the influence of gravity is reduced, and the sagging of the liquid can be suppressed. The region where the outer diameter is gradually reduced near the end of the support is a non-image forming region in the copying process.

The area of the electrophotographic photosensitive member support of the present invention which is provided in the vicinity of the end portion and has a gradually decreasing outer diameter may be formed by simultaneously performing the surface processing on the surface of the support described above. A portion where the outer diameter on the end side deviating from the gradually decreasing area is larger than the minimum outer diameter of the gradually decreasing area, that is, the formation of the protrusion is surface-treated in the same manner as above, or is made of a material different from the material of the support, It is also possible to form the protruding portion by using a material that does not dissolve in the solvent of the photosensitive layer forming liquid in the coating tank as the protruding portion forming member and adhering this member so as to be integrated with the support body. If the height of the protruding portion that is set is such that there is a problem in handling the photoconductor after the photoconductor layer is formed on the support or a problem when the photoconductor is loaded into the copying machine, I won't.

Next, the specific shape of the electrophotographic photosensitive member support of the present invention will be described with reference to FIGS. 1, 2 and 3.
FIG. 1 shows the electrophotographic photosensitive member support of the present invention in which the outer diameter of the support corresponding to the non-image forming region gradually decreases from the center of the support toward the end of the support. Is decreasing linearly, and B is decreasing exponentially. In the present invention, the shape of the gradually decreasing region is not limited to these two examples. 2 and 3, the relationship between the outer diameter d1 of the support corresponding to the non-coating portion and the minimum outer diameter d2 of the outer diameters of the support corresponding to the non-image forming area is d1> d2, and The outer diameter of the support corresponding to the image forming region is gradually reduced from the center side of the support toward the end side of the support to show the support for an electrophotographic photoreceptor of the present invention. In the case of the support as shown in FIG. 2, the shorter the non-coating portion, that is, the portion of a1, the shorter the non-image forming area (corresponding to a and b in the figure) can be. This is a preferable configuration for downsizing a machine such as a machine. In addition, the non-coating portion, that is, the portion a1 is provided with an abutting member such as a roller for keeping the gap between the photoconductor and the developing sleeve constant when the photoconductor is mounted on a copying machine or a printer. Although it abuts on both ends, it can also be used as a receiving portion for this butting member.

In order to prepare a photoconductor using the electrophotographic photoconductor support of the present invention, an area in which the outer diameter of the support cylinder is gradually reduced is provided in a coating tank filled with a photosensitive layer forming liquid. The support is inserted into the coating tank with the end of the support facing upward, and the support is immersed in the liquid until the above-mentioned gradually decreasing region of the support is immersed. Then, the photosensitive layer forming liquid is applied by pulling the support upward, and the final electrophotographic photosensitive member can be obtained through the drying step which is the next step. Of the electrophotographic photosensitive member support of the present invention, in particular, a support having a portion where the outer diameter on the end side outside the region where the outer diameter is gradually reduced is larger than the minimum outer diameter of the gradually reduced region, that is, a support having a protruding portion. For the body,
When the support is dipped so as to be in contact with the coating liquid up to the peaks of the protrusions during dip coating, the contact area between the liquid and the support is larger than that of the support of the present invention having no protrusions, resulting in less sagging of the liquid. . The electrophotographic photosensitive member using this support is in a state where the protruding portion of the support and the photosensitive layer are in contact with each other, and it is ensured that the effective area of the coated photosensitive layer is maximized. You can control.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples.

【Example】

Example 1 One end of an aluminum cylinder having an outer diameter of 80 mm, a length of 360 mm and a thickness of 3 mm was surface-treated by cutting as shown in FIG. (D1 = 80 mm, d2 = 76 mm, a
1 = 15 mm) In this case, 20 mm from the machined end of the cylinder is the non-image forming area. Next, 9 parts by weight of a charge transport material having the following structural formula, 10 parts by weight of a polycarbonate resin Iupilon Z200 (manufactured by Mitsubishi Gas Chemical Co., Ltd.), and a silicone oil KF-50 (manufactured by Shin-Etsu Chemical Co., Ltd.)
0.002 parts by weight is dissolved in 88 parts by weight of methylene chloride,
A charge transport layer forming coating solution was prepared. The prepared charge transport layer forming coating solution is filled in a coating tank having an inner diameter of 105 mm, and the aluminum cylinder is immersed in the layer forming coating solution in the coating tank so that the cylinder axis is vertical. At this time, the aluminum cylinder is immersed while leaving the upper end 2 mm. Dip until the coating liquid comes into contact with the peaks of the protrusions located above. Then, the aluminum cylinder was pulled up to complete the coating process, and the coated surface of the drum was dried at 120 ° C. for 20 minutes. The film thickness of the charge transport layer obtained through the drying step was measured with an eddy current film thickness meter (manufactured by Fisher). 20mm and 180m from the upper end of dip coating
m, and the thickness of each film is 20 mm.
The points at μm and 180 mm were 25 μm. From this result, it was confirmed that the photosensitive layer was formed in a relatively uniform film thickness without the influence of sagging at the edge of the image forming area of the photosensitive layer.

[0010]

[Chemical 1]

Comparative Example 1 A charge transport layer was formed on an aluminum cylinder in the same manner as in Example 1 except that the end portion of the aluminum cylinder was not surface-treated as in Example 1. When the film thickness of the formed charge transport layer was measured in the same manner as in Example 1, it was 15 μm at a position 20 mm from the upper end of the dip coating, and the same 180
The mm portion was 25 μm, and the difference in film thickness was large.

Example 2 One end of an aluminum cylinder having an outer diameter of 80 mm, a length of 360 mm and a thickness of 3 mm was surface-treated by cutting as shown in FIG. (D1 = 80 mm, d2 = 76 mm, a
2 = 2 mm, b2 = 15 mm) A charge transport layer was formed on an aluminum cylinder in the same manner as in Example 1 except that the above shape was processed. When the film thickness of the formed charge transport layer was measured in the same manner as in Example 1, it was found that a portion 20 mm from the upper end of the dip coating was 24 μm and a portion 180 mm from the same was 25 μm, showing that a uniform film thickness was formed. confirmed. At this time, the minimum outer diameter part d
The second part was covered with the charge transport layer.

Example 3 Butyral resin S-REC BLS [Sekisui Chemical Co., Ltd.]
Preparation] 10 parts by weight is dissolved in 150 parts by weight of cyclohexanone, 1.2 parts by weight of a trisazo pigment having the following structural formula, which is a charge-generating substance, is added, and the mixture is dispersed for 48 hours in a ball mill, and 210 parts by weight of cyclohexanone is added. Dispersion was performed for 3 hours. This was taken out of the container and the solid content was 1.
The mixture was diluted with cyclohexanone with stirring so that the concentration became 0% by weight. The thus-obtained coating liquid for forming a charge generation layer was applied onto the charge transport layer on the aluminum drum prepared in Example 1 by spray coating and then at 120 ° C. for 1
By drying under the condition of 0 minutes, a charge generating layer having a thickness of 3 μm was formed and an electrophotographic photosensitive member was prepared.

[0014]

[Chemical 2]

Next, the photoconductor thus prepared was loaded into a commercially available electrophotographic copying machine Imagio 320 (manufactured by Ricoh Co., Ltd.) which was modified, and the charging characteristics of the photoconductor were evaluated. In the modified part of the copying machine, the polarity of the charger was reversed, and the charger, quenching lamp, and laser writing optical system were activated without paper passing. Is attached. The electrophotographic copying machine was used to perform the copying process, and the charging characteristics of the photoconductor were measured.The following results were obtained, and the charging characteristics at the edges of the photoconductor did not differ from other areas. It was confirmed to be acceptable.

Comparative Example 2 An electron was prepared in the same manner as in Example 3 except that the charge transport layer of Example 1 used in Example 3 was replaced by the charge transport layer obtained in Comparative Example 1 and the support. A photographic photoreceptor was created. This electrophotographic photosensitive member was loaded in a copying machine in the same manner as in Example 3, and the charging characteristics of the photosensitive member were measured.
The following results were obtained, and it was confirmed that the charging characteristics at the end portion of the photoconductor largely differ from those of other regions, and are unacceptable as a photoconductor.

Example 4 An electron was prepared in the same manner as in Example 3 except that the charge transport layer of Example 1 used in Example 3 was replaced by the charge transport layer obtained in Example 2 and the support. A photographic photoreceptor was created. Then, when the charging characteristics of the photoconductor were measured,
The following results were obtained, and it was confirmed that there was no difference in the charging characteristics at the edge portion of the photoconductor from other regions, and the photoconductor had no problem in use.

[0018]

INDUSTRIAL APPLICABILITY According to the present invention, an electrophotographic photosensitive member is obtained in which the photosensitive layer formed by dip coating on the electrophotographic photosensitive member support has a uniform film thickness over the entire surface of the support. It is apparent that the support and the electrophotographic photosensitive member including the support can be manufactured, and as a result, the charging characteristics of the photosensitive member are sufficiently and at the same level over the entire area of the formed photosensitive layer. The electrophotographic photosensitive member support and the electrophotographic photosensitive member can reduce the size of the photosensitive member and further reduce the size of the electrophotographic copying machine.

[0019]

[Brief description of drawings]

FIG. 1 is a cross-sectional view of an example of an electrophotographic photosensitive member support of the present invention.

FIG. 2 is a cross-sectional view of an example of the electrophotographic photosensitive member support of the present invention.

FIG. 3 is a cross-sectional view of an example of the electrophotographic photosensitive member support of the present invention.

[Explanation of symbols]

a1 non-image forming area, b1 image forming area, a2 non-coating portion, b2 non-image forming area, c2 image forming area,
d1 outer diameter, d2 outer diameter

Claims (3)

[Claims] 1. A cylindrical support for an electrophotographic photosensitive member used for forming an electrophotographic photosensitive layer by a dip coating method, wherein an outer portion near an end of the support which is located above the dip coating direction. A support for an electrophotographic photosensitive member, wherein the diameter gradually decreases from the center side of the support to the end side of the support. 2. A cylindrical electrophotographic image having a region in which the outer diameter near the end of the support, which is above the dip coating direction, gradually decreases from the center of the support toward the end of the support. A support for an electrophotographic photosensitive member, wherein an outer diameter of an end portion side of the support for the photosensitive member which is deviated from the gradually decreasing region is larger than a minimum outer diameter of the gradually decreasing region. 3. An outer diameter in the vicinity of the end of the support, which is on the upper side with respect to the dip coating direction, has a region in which it gradually decreases from the center of the support toward the end of the support, and In an electrophotographic photosensitive member having an electrophotographic photosensitive layer provided on a cylindrical support for an electrophotographic photosensitive member, the outer diameter of the end side deviating from the gradually decreasing region is larger than the minimum outer diameter of the gradually decreasing region. An electrophotographic photosensitive member, characterized in that a part up to a region having a minimum outer diameter is covered with an electrophotographic photosensitive layer.