JP3477897B2 - Electrophotographic photoreceptor coating equipment - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coating device for forming a photosensitive layer of an electrophotographic photoreceptor, and more particularly to a structure for purifying a coating liquid in a coating tank which constitutes a part of the coating device.

[0002]

2. Description of the Related Art FIG. 3 is a cross-sectional view of an essential part showing a layer structure of an electrophotographic photosensitive member. A cylindrical conductive substrate having a stabilizing treatment layer 7b formed on the surface of a raw tube 7a made of aluminum or the like. 7, a charge generation layer 11a and a charge transport layer 11 made of a photoconductive material are formed on the surface of the cylindrical conductive substrate 7.
b is formed in layers to form the photosensitive layer 11.

In recent years, with the development of printing apparatuses having high image quality functions, even a slight variation in film thickness, which has not been a problem in the conventional photosensitive layer, leads to a drastic decrease in the function thereof. The dipping method that can form a film and can obtain a more uniform film thickness is widely adopted as a simple method. In the dipping method, a photoconductive material is dissolved or dispersed in an organic solvent together with a binder resin, and if necessary, an adhesive or a plasticizer is further added to prepare a coating solution, and the coating solution is filled into a cylindrical conductive solution. The base material is dipped, then the base material is pulled up and the coating liquid adhering to the surface of the base material is dried to form a thin film layer.

FIG. 4 is a cross-sectional view showing the structure of a coating apparatus according to the prior art, which is a coating tank 1, a storage tank 2, a pipe 3,
3 a, 3 b, 3 c, a circulation pump 5, a filter 6 and the like, the coating tank 1 is filled with the coating solution 8, and the coating solution 8 overflowing from the coating tank 1 has a donut shape surrounding the outer periphery of the coating tank 1. From the saucer 1a, it is made to flow from the upper part into the storage tank 2 through the pipe 3 connected to the saucer 1a. Further, the circulation pump 5 and the filter 6 are connected via the pipe 3b between the pipe 3a provided in the lower part of the storage tank 2 and the pipe 3c provided in the lower part of the coating tank 1, and the storage tank 2
And the coating tank 1 are connected to each other, the coating liquid 8 in the storage tank 2 is transferred by driving the circulation pump 5, and a supply port is opened at the end of the pipe 3c without any step with the inner surface of the bottom plate 1b of the coating tank 1. The coating liquid 8 is made to flow into the coating tank 1 from 9 and constantly circulated so that the coating liquid 8 overflows from the upper part of the coating tank 1 to keep the liquid level of the coating tank 1 constant. Further, a cover 4 having a hole 4a into which the cylindrical conductive substrate 7 can be inserted is detachably attached to the opening of the tray 1a, and the cylindrical conductive substrate 7 is inserted through the hole 4a in the direction of arrow P. An elevating device (not shown) is provided on the lateral side of the coating tank 1 for lowering it to immerse it in the coating liquid 8 and then raising it in the direction of arrow Q.

On the other hand, in the above-mentioned coating apparatus, as shown in the partially cutaway perspective view of the cylindrical conductive substrate of FIG. 5, a sealing lid 12 is attached to the upper part of the cylindrical conductive substrate 7 so that the coating liquid is almost completely contained inside the substrate. The cylindrical conductive substrate 7 is immersed in the coating liquid 8 so as not to enter. Then, when pulled up and dried, the coating liquid slightly entering and adhering to the inner surface of the lower end of the cylindrical conductive substrate 7 remains as dry powder 13. In order to remove the dry powder 13, as shown in the cross-sectional view of the cylindrical conductive substrate in a wiped state of FIG.
5 is provided with a device for wiping off the dry powder 13 by spraying the solvent droplets 16 while rotating the wiping bobbin 14 having the liquid supply nozzle 15a and the liquid supply nozzle 15a. Further, during the coating process, before and after the above-mentioned dip coating, the cylindrical conductive substrate 7 is temporarily fixed using the mounting bobbin 17 having a truncated cone shape as shown in the sectional view of the mounting state of the cylindrical conductive substrate of FIG. Often placed. Regarding the mounting bobbin 17, in particular, a perspective view of FIGS. 8 and 9 has a shape in which the contact point between the inner surface of the lower end of the cylindrical conductive substrate 7 and the surface of the mounting bobbin 17 is reduced to suppress the generation of dust due to the contact. There is a round mounting bobbin 17a and a star mounting bobbin 17b respectively shown in FIG.

The above-mentioned coating process is sequentially repeated with different coating devices corresponding to the number of laminated layers to form a laminated photosensitive layer on the cylindrical conductive substrate.

[0007]

However, according to the above-mentioned coating apparatus, the cylindrical conductive substrate is dipped by the dipping method,
Then, in the process of pulling up to form a photosensitive layer on the surface of this substrate, dry powder and the like formed on the inner surface of the lower end of the cylindrical conductive substrate, abrasion powder generated from the mounting bobbin and equipment used, and other dust in the air. Dust such as may mix in the coating liquid. The dust floating in the coating liquid is trapped by the filter installed in the circulation passage if it flows out into the circulation passage due to the overflow of the coating liquid. It is easily stirred in the vicinity of the supply port due to the inflow of the coating solution and repeatedly floats and sinks, so that it is likely to remain in the coating tank, and the amount of residual dust increases. The residual dust reattaches to the surface of the cylindrical conductive substrate to cause coating unevenness, which results in unevenness in the electrical characteristics of the photoconductor. If this photoconductor is used in an electrophotographic apparatus, image density unevenness or the like is caused, which causes printing defects.

The present invention has been made in view of the above problems, and an object thereof is to prevent dusts remaining in the coating liquid from adhering to the surface of a cylindrical conductive substrate in order to eliminate coating unevenness which causes defective printing. It is an object of the present invention to provide an electrophotographic photoconductor coating device that can obtain good printing quality by suppressing the suppression.

[0009]

According to the present invention, the aforementioned object is to provide a coating tank having a coating solution for forming a photosensitive layer coating film on the outer surface of a cylindrical conductive substrate by a dipping method, and the coating tank. In the coating apparatus of the electrophotographic photoreceptor, the coating liquid is supplied from the supply port provided at the bottom of the tank, and the coating liquid circulating mechanism that re-supplies the coating liquid overflowing from the upper part is applied. Provided at the bottom of the tank and almost vertically above
The opening surface of the supply port opening toward the upper side is higher than the deepest part of the coating tank, and sedimentation dust is accumulated at the bottom of the coating tank.
This is achieved by using a coating device having a distillate .

[0010]

In summary, the present invention provides the coating liquid supply port at a position higher than the deepest part of the coating tank so that the residual dust in the coating tank will settle to a position lower than the coating liquid supply port. This is to make the residual dust that has settled less likely to float by being retained at the bottom of the coating tank by making it less likely to be affected by the stirring action due to the inflow of the. As a result, the coating liquid in the coating tank is purified and the adhesion of dust to the surface of the cylindrical conductive substrate can be suppressed, so that uneven coating is less likely to occur.

[0011]

EXAMPLE FIG. 1 shows a sectional view of a photosensitive layer coating apparatus for an electrophotographic photosensitive member according to Example 1, and FIG. 2 shows another example 2 in which the circled portion R in FIG. 1 is replaced. The sectional view of a tank is shown. Hereinafter, description will be given with reference to FIG. The structure of this coating apparatus is as follows: coating tank 1, storage tank 2, pipes 3, 3a, 3
b, 3c, a circulation pump 5, a filter 6, etc., and a position where the opening surface of the supply port 9 for the coating liquid 8 is higher than the deepest part of the coating tank 1 in the configuration of the conventional example shown in FIG. The configuration is similar to that of the conventional coating device shown in FIG. 4, except that the settling dust 10 accumulates at the bottom of the coating tank 1 to form a retention reservoir 10a. (Example 1) Diameter 80 mm as the cylindrical conductive substrate 7
× Aluminum tube with a length of 350 mmL (JIS606
Prepared after 3) degreasing / cleaning treatment, anodizing treatment (15% sulfuric acid at temperature 20 ° C for 24 minutes) and sealing treatment (using nickel acetate, temperature 60 ° C for 8.5 minutes). In the coating apparatus shown in FIG. 1, the coating tank 1 has a cylindrical shape with a diameter of 120 mm and an effective depth of 470 mmL, and its bottom is formed into a bowl shape.
A circular tube with a diameter of 20 mm is 50 m in the center of the
After the coating solution flow rate is set to 25 l / min, the coating solution supply port 9 projecting from m is used, and after performing a normal coating process on about 10,000 cylindrical conductive substrates,
A print inspection and an appearance inspection were performed on all the pieces to confirm the defect occurrence rate, and the round mounting bobbin 17a and the star mounting bobbin 17b used in the coating process were observed for the contact portion with the cylindrical conductive substrate. The dust adhesion status was confirmed. (Example 2) In the coating apparatus described in Example 1, the defect occurrence rate was examined and confirmed in the same manner as in Example 1 except that the vertical cross-sectional shape of the bottom plate 1b was replaced with a coating tank having the bottom plate 1c shown in FIG. (Comparative Example) The defect occurrence rate was checked and confirmed in the same manner as in Example 1 using the coating apparatus shown in FIG. 4 in which the bottom plate 1b is flat and the supply port 9 does not project.

The results are shown in Table 1.

[0013]

[Table 1] As can be seen from Table 1, in Examples 1 and 2 in which the opening surface of the coating liquid supply port 9 was provided at a position higher than the deepest part of the coating tank, the printing and appearance defect occurrence rates were significantly higher than those of Comparative Examples. Has been reduced and improved.

Regarding the shape of the bottom plate of the coating tank, the bottom plate 1c shown in FIG. 2 is more effective in reducing the defect occurrence rate than the bottom plate 1b shown in FIG.

[0015]

According to the present invention, a coating tank having a coating liquid for forming a photosensitive layer coating film on the outer surface of a cylindrical conductive substrate by the dipping method, and a supply provided at the bottom of the coating tank. In a coating device for an electrophotographic photosensitive member, which is provided with a coating liquid circulating mechanism that supplies the coating liquid from a mouth and reflows the coating liquid that overflows from the upper part from the supply port, a substantially vertical upper portion provided at the bottom of the coating tank. Supply port opening toward
The opening surface of is higher than the deepest part of the coating tank, and the bottom of the coating tank
By having a retention pool in which the settling dust accumulates , the residual dust in the coating tank settles and stays at the bottom of the coating tank to make it difficult to float, and the coating liquid in the coating tank is purified to make a cylindrical conductive substrate. Since it is possible to suppress the adhesion of dust to the surface of the electrophotographic photosensitive member, it is possible to manufacture an electrophotographic photosensitive member having a uniform film thickness and no image density unevenness. It becomes possible to provide a photoreceptor.

[Brief description of drawings]

FIG. 1 is a sectional view of a photosensitive layer coating apparatus for an electrophotographic photosensitive member according to this embodiment.

FIG. 2 is a sectional view of a coating tank according to another embodiment.

FIG. 3 is a sectional view of an essential part showing the layer structure of an electrophotographic photoreceptor.

FIG. 4 is a sectional view of a coating device according to a conventional example.

FIG. 5 is a partially cutaway perspective view of a cylindrical conductive substrate.

FIG. 6 is a cross-sectional view showing a state of wiping the inner surface of a cylindrical conductive substrate.

FIG. 7 is a sectional view showing a mounted state of a cylindrical conductive substrate.

FIG. 8 is a perspective view of a round mounting bobbin.

FIG. 9 is a perspective view of a star-mounted bobbin.

[Explanation of symbols]

1 coating tank 1b Bottom plate 1c bottom plate 3c piping 7 Cylindrical conductive substrate 8 coating liquid 9 supply port 10 Settling dust 10a Retention reservoir

Front page continuation (58) Fields surveyed (Int.Cl. ⁷ , DB name) B05C 3/02-3/09 B05C 11/10 G03G 5/05 102

Claims (2)

(57) [Claims] 1. A coating tank having a coating liquid for forming a photosensitive layer coating film on the outer surface of a cylindrical conductive substrate by a dipping method,
In a coating device for an electrophotographic photoreceptor, which is provided with a coating liquid circulating mechanism for supplying the coating liquid from a supply port provided at the bottom of the coating tank and re-supplying the coating liquid overflowing from the upper part from the supply port. , Provided with lead on the bottom of the coating tank
The opening surface of the supply port that opens directly above is higher than the deepest part of the coating tank, and settling dust accumulates at the bottom of the coating tank.
An electrophotographic photoconductor coating apparatus having a retention pool . 2. The coating device for an electrophotographic photosensitive member according to claim 1, wherein the opening surface of the supply port provided at the bottom of the coating tank is 50 mm or more higher than the deepest portion of the coating tank.