JPH10246969A - Coating device for electrophotographic photoreceptor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coating device for electrophotographic photoreceptor capable preventing the coating unevenness from occurring on the outer surface of a cylindrical substrate being dipped in a coating vessel by equalizing the flow of coating liquid in the coating vessel and preventing the increase of the over flowing quantity, the circulating flow quantity, or the like, in the coating device provided with a coating vessel of a large capacity. SOLUTION: In this coating device 1 provided with the coating liquid 2 containing the photoconductive material, a cylindrical substrate 6 is vertically immersed to form a photosensitive layer coating film. In this case, by vertically immersing a hollow body 5 of a cylindrical shape equipped with a plugging cap 5a provided with an outside diameter smaller than the inside diameter of the cylindrical substrate 6 on the bottom part while on the center part of the coating vessel 1, the quantity of the coating liquid 2 equivalent quantity to the immersion volume of the hollow body 5 can be reduced while the over flowing quantity, the circulate-flowing quantity and the quantity filling the coating vessel 1 of the coating liquid 2 can be reduced, hence the flowing state of the coating liquid 2 in the coating vessel 1 can be made gentle and the liquid can be easily rectified and uniformized, and thus the uniform photosensitive layer coating can be formed on the outer surface of the cylindrical substrate 6.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a coating apparatus for forming a photosensitive layer of an electrophotographic photosensitive member.

[0002]

2. Description of the Related Art A photoreceptor used in an electrophotographic application apparatus is generally formed by applying a coating solution containing a photoconductive material to an outer surface of a cylindrical substrate made of aluminum or the like to form a coating film of a photosensitive layer. It is manufactured by As the coating method, there are a dip coating method, a spray coating method, a ring coating method, etc., but an arbitrary film thickness can be obtained relatively uniformly.
In addition, a dip coating method with high productivity is generally adopted.

[0003] In the dip coating method, a photoconductive material is dissolved or dispersed in an organic solvent together with a binder resin, and in some cases, an inner layer is placed in a coating tank filled with a coating liquid prepared by adding an adhesive or a plasticizer. A series of coatings is formed by mounting a cylindrical base with its upper end sealed to an elevating mechanism to lower it vertically, immersing it, and then pulling it up to dry the coating liquid adhering to its outer surface in order to prevent the coating liquid from entering the surface. The photosensitive layer coating film was formed by sequentially repeating the steps in the order of lamination.

An outline of the configuration of a coating apparatus for an electrophotographic photosensitive member by a dip coating method will be described with reference to the drawings.
FIG. 5 is a cross-sectional view showing an example of a coating apparatus according to the related art, which shows a coating tank 1 filled with a coating liquid 2 for forming a photosensitive layer coating film on the outer surface of a cylindrical substrate 6, and a coating tank 1. A storage tank 3b for storing the liquid 2, a collection pipe 3a for collecting the coating liquid 2 overflowing from the upper edge of the coating tank 1 into the storage tank 3b, and a supply port from the storage tank 3b to the bottom of the coating tank 1. 1 includes a circulation mechanism 3 having a pressure feed pump 3c and a filter 3d for supplying the coating liquid 2 to 1a, and an elevating mechanism 7 for elevating and lowering the cylindrical substrate 6.

In the coating apparatus having the above structure, the coating liquid 2 stored in the storage tank 3b is pressure-fed from the storage tank 3b into the coating tank 1 through the supply port 1a at the bottom of the coating tank 1 by driving a pressure pump 3c. The coating liquid 2 is constantly overflowed from the upper edge of the coating tank 1 so that the liquid level of the coating tank 1 is maintained at a constant level, and the overflowing coating liquid 2 is collected in the storage tank 3b via the collection pipe 3a. The liquid 2 is circulating.

In the step of forming the photosensitive layer coating film, the cylindrical substrate 6 is mounted on the elevating mechanism 7, and the cylindrical substrate 6 is first lowered in the direction of arrow P and immersed in the coating tank 1. The same amount of the coating liquid as the immersion volume of 6 overflows from the coating tank 1 and is stored in the storage tank 3b through the collection pipe 3a. Then, the cylindrical substrate 6 is raised in the direction of arrow Q to remove the coating liquid from the inside of the coating tank 1. When the coating liquid is lifted, the same amount of the coating liquid as the lifting volume of the cylindrical substrate 6 is immediately supplied from the storage tank 3b into the coating tank 1 through the supply port 1a at the bottom of the coating tank 1 by the driving of the pressure pump 3c. The liquid level was kept constant.

[0007] Conventional photoconductors are mainly mounted on an electrophotographic apparatus in the field of low- and medium-speed machines in which the paper is A3 size or smaller, so that the outer diameter is 24 mm to 80 mm and the length is 230 m.
Cylindrical substrates in the range of m to 400 mm have been commonly used. Therefore, as a coating apparatus for manufacturing a photoreceptor of a conventional size, a relatively small one having an overflow amount of about 2 liters or less and a coating tank capacity of about 20 to 30 liters has been used.

[0008]

With the recent advances in electrophotographic technology and organic material technology, there has been a rapid increase in the demand for paper that can handle A0 size paper and that can be applied to high-speed machines. 160mm, maximum length 11
A large-sized coating tank capable of coating a cylindrical substrate with a spill amount of 10 times or more as compared with the largest conventional coating apparatus, since a cylindrical substrate of 00 mm is required. Is required, and the circulating flow rate of the coating liquid is also increased, which results in an increase in the size of the coating apparatus.

According to the prior art, when a large cylindrical substrate is immersed in a large-volume coating tank and pulled up, the amount of the coating liquid overflowing from the coating tank increases and the coating liquid supplied to the coating tank is increased. The supply rate of the coating liquid also increases, causing the flow state of the coating liquid in the coating tank to change rapidly, causing the flow of the coating liquid to become non-uniform. As a result, there is a quality problem that the non-defective rate of the photosensitive member is reduced. If a photoreceptor having coating unevenness on the surface is erroneously mounted on the electrophotographic apparatus, it causes a non-uniformity of the electric characteristics and causes a serious defect for the electrophotographic apparatus that image density unevenness occurs. There were concerns.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a coating apparatus using a large-volume coating tank, while suppressing the overflow of the coating liquid and the increase in the circulating flow rate, Uniform flow of the coating solution in the tank,
An object of the present invention is to provide an electrophotographic photoreceptor coating apparatus capable of avoiding coating unevenness occurring on the outer surface of a cylindrical substrate immersed therein.

[0011]

SUMMARY OF THE INVENTION According to the present invention, there is provided the above-mentioned object, in which a cylindrical substrate is vertically immersed in a coating tank having a coating solution containing a photoconductive substance, and a photosensitive layer is coated on the outer surface thereof. In an electrophotographic photoreceptor coating apparatus for forming a film, a cylindrical hollow body having an outer diameter smaller than the inner diameter of a cylindrical substrate and having a lid provided at a lower end is provided at the center of the coating tank. Achieved by the vertical arrangement. Then, the hollow body is set so that the open upper end is located at a position higher than the upper edge of the coating tank, or the upper end is closed with an upper lid, and the mounting attached to the lower part in the coating tank is attached. It is preferable to be fixed via a tool, and it is preferable that the mounting tool is provided with a guide piece for rectifying the coating liquid flowing into the coating tank.

According to the above configuration, the amount of the coating liquid overflowing from the coating tank becomes an overflow amount obtained by subtracting the immersion volume of the hollow body provided in the coating tank, and is supplied into the coating tank accordingly. Since the supply amount is also reduced, the circulation flow rate of the coating liquid can be reduced, and the flow state of the coating liquid in the coating tank can be moderated. By arranging the guide pieces and the like, rectification and uniformization can be easily performed, and a uniform photosensitive layer coating film can be formed on the outer surface of the cylindrical substrate immersed therein.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A coating apparatus for an electrophotographic photosensitive member according to the present invention will be described with reference to FIGS. 1, 2, 3 and 4. FIG. FIG. 1 is a sectional view of a coating apparatus according to a first embodiment of the present invention, which shows a coating tank 1 filled with a coating liquid 2 containing a photoconductive substance and a storage tank for storing the coating liquid 2. A tank 3b, a recovery pipe 3a for collecting the coating liquid 2 overflowing from the upper edge of the coating tank 1 into a storage tank 3b, and supplying the coating liquid 2 from the storage tank 3b to a supply port 1a at the bottom of the coating tank 1. Circulating mechanism 3 having a pressure pump 3c and a filter 3d, and an elevating mechanism 7 for elevating and lowering the cylindrical substrate 6, and having an outer diameter smaller than the inner diameter of the cylindrical substrate 6 and a lower end portion. A cylindrical hollow body 5 provided with a lid 5a is vertically fixed to the center of the coating tank 1 via a fixture 8.

In the step of forming a photosensitive layer coating film using the coating apparatus having the structure shown in FIG. 1, the cylindrical body 6 mounted on the elevating mechanism 7 is lowered in the direction of arrow P so that the hollow body 5 is When immersed in the coating tank 1 so as to be inserted into the inside of the cylinder, the product of the annular area sandwiched between the outer periphery of the cylindrical body 6 and the outer periphery of the hollow body 5 and the immersion depth of the cylindrical body 6 is obtained. The same amount of the coating liquid as the volume determined by the formula (1) overflows from the coating tank 1 and is stored in the storage tank 3b. Then, the cylindrical base 6 is raised in the direction of arrow Q and pulled up from the inside of the coating tank 1. The same amount of coating liquid as the volume determined by the product of the annular area sandwiched between the outer circumference of the hollow body 5 and the outer circumference of the hollow body 5 and the pull-up length of the cylindrical base 6 is driven through the circulation mechanism 3 by driving the pump 3c. Is supplied from the supply port 1a at the bottom of the coating tank 1 into the coating tank 1 for coating. 1 of the liquid surface is kept constant.

By providing the hollow body 5 as described above, it is possible to reduce the overflow amount and the circulation flow rate of the coating liquid equivalent to the immersion volume of the hollow body 5 and to apply the coating liquid for filling the coating tank 1. Similarly, since the flow rate of the coating liquid 2 in the coating tank 1 becomes gentle and can be easily adjusted, the flow can be made uniform by the rectifying means.

FIG. 2 is a perspective sectional view of a coating tank showing a second embodiment according to the present invention. The coating tank has an outer diameter smaller than the inner diameter of the cylindrical base 6 and is provided with a lid 5a at the lower end. The coating tank 1 is attached via a fixture 8 attached to the lower part of the coating tank 1 such that the upper end opening the hollow cylindrical body 5 is higher than the upper edge of the coating tank 1. The structure is fixed vertically to the center.

According to the configuration shown in FIG. 2, the structure of the hollow body 5 is relatively simple, and the upper end of the hollow body 5 is always above the upper edge of the coating tank 1, that is, the level of the overflowing liquid of the coating liquid 2. Because there is
Even if the upper end is open, the hollow state can be maintained, and the positioning operation when the cylindrical base 6 is lowered and raised in the directions of arrows P and Q can be easily performed. FIG.
FIG. 5 is a perspective sectional view of a coating tank according to a third embodiment of the present invention, which has an outer diameter smaller than the inner diameter of the cylindrical base body 6, has a lower end provided with a cover 5 a, and has an upper end provided with an upper cover. The cylindrical hollow body 5 sealed by 5b is vertically fixed to the center of the coating tank 1 via a fixture 8 attached to a lower part in the coating tank 1.

According to the structure shown in FIG. 3, the upper end of the closed hollow body 5 provided with the upper lid 5b is located at the upper edge of the coating tank 1, that is, above or below the overflowing surface of the coating liquid 2. Can maintain a hollow state. FIG. 4 is a perspective view of a mounting member for a hollow body showing a fourth embodiment according to the present invention, in which a plurality of guide pieces 4a for rectifying the coating liquid are radially formed on the lower outer surface of the hollow body 5. It is possible to position the hollow body 5 at the center of the coating tank by disposing, fixing the outer end of each guide piece 4a to the annular support 4b, and fixing the support 4b to the inner wall at the lower part of the coating tank. This is a possible configuration.

By disposing the fixture shown in FIG. 4, the coating liquid supplied from the supply port at the bottom of the coating tank rises while spreading along the surface of the lid 5a provided at the lower end of the hollow body 5. Then, since the flow is regulated when the air flows at a low speed and passes between the guide pieces 4a, the flow becomes uniform on the outer surface of the cylindrical base body immersed on the outflow side (upper side) of the guide piece 4a. A coating liquid can be supplied. (Example 1) A closed hollow body was prepared in which an upper lid having a thickness of 10 mm was attached to the upper end of a cylinder having an outer diameter of 90 mm and an effective length of 1100 mm, and a lower lid having a substantially spherical outer shape having a depth of 30 mm. , 3 on the lower outer surface of this hollow body
Six guide pieces are evenly arranged radially, and the outer end of each guide piece is fixed to an annular support having an outer diameter of 180 mm and a width of 20 mm to form a fixture.
A support having a height of 80 mm and an effective depth of 1100 mm is prepared. The support is positioned so that the hollow body is disposed vertically in the center of the coating tank, and the outer surface of the support is fixed to the inner wall at the bottom of the coating tank. did.

In the coating apparatus having the above-mentioned coating tank,
A cylindrical substrate having an outer diameter of 100 mm, a thickness of 3 mm, and a length of 1000 mm was subjected to dip coating to visually inspect the state of formation of the photosensitive layer coating film. As a result, it was confirmed that application unevenness did not occur. Example 2 Example 2 was the same as Example 1 except that the outer diameter of the cylindrical substrate was 160 mm.

As a result, it was confirmed that no coating unevenness occurred. (Comparative Example) A coating tank for dip coating having an inner diameter of 180 mm and an effective depth of 1100 mm was prepared in the same manner as in Example 1, and the same cylindrical shape as in Example 1 was used in a conventional coating apparatus equipped with this coating tank. The substrate was subjected to dip coating to visually inspect the state of formation of the photosensitive layer coating film.

As a result, it was confirmed that uneven coating occurred on the lower portion of the cylindrical substrate.

[0023]

According to the present invention, an electrophotographic method for forming a photosensitive layer coating film on the outer surface by vertically immersing a cylindrical substrate in a coating tank having a coating solution containing a photoconductive substance is provided. In the photoreceptor coating device, by having a cylindrical hollow body having an outer diameter smaller than the inner diameter of the cylindrical base and having a lid provided at the lower end vertically disposed in the center of the coating tank, Since the amount of the coating solution overflowing and the circulation amount equal to the immersion volume of the hollow body can be reduced, and the amount of the coating solution for filling the coating tank can also be reduced, the flow state of the coating solution in the coating tank is moderate. Therefore, the flow can be made uniform because the rectifying means becomes easy. As a result, it is possible to avoid the occurrence of coating unevenness on the outer surface of the cylindrical substrate immersed therein, and it is also possible to reduce the size of the coating device.

[Brief description of the drawings]

FIG. 1 is a sectional view of a coating apparatus showing a first embodiment according to the present invention.

FIG. 2 is a perspective sectional view of a coating tank showing a second embodiment according to the present invention.

FIG. 3 is a perspective sectional view of a coating tank showing a third embodiment according to the present invention.

FIG. 4 is a perspective view of a fixture for a hollow body showing a fourth embodiment according to the present invention.

FIG. 5 is a sectional view showing an example of a coating apparatus according to a conventional technique.

[Explanation of symbols]

 1 ... coating tank 2 ... coating liquid 4a ... guide piece 5 ... hollow body 5a ... closing lid 5b ... top lid 6 ... ..... cylindrical substrate 8 .....

Claims (4)

[Claims] An electrophotographic photoreceptor coating apparatus for vertically immersing a cylindrical substrate in a coating tank having a coating solution containing a photoconductive substance to form a photosensitive layer coating on its outer surface. The electrophotographic apparatus according to claim 1, wherein a cylindrical hollow body having an outer diameter smaller than the inner diameter of the cylindrical substrate and having a lid provided at a lower end portion is disposed vertically in the center of the coating tank. Coating device for photoreceptors. 2. The hollow body is fixed via a fixture attached to a lower portion of the coating tank such that an open upper end is positioned higher than an upper edge of the coating tank. The coating apparatus for an electrophotographic photoreceptor according to claim 1, wherein: 3. The electrophotographic apparatus according to claim 1, wherein the hollow body is sealed at its upper end with an upper lid and fixed via a fixture attached to a lower portion in the coating tank. Photoconductor coating device. 4. A coating apparatus for an electrophotographic photoreceptor according to claim 2, wherein said fixture has a guide piece for rectifying the coating liquid flowing into said coating tank. .