JPH0214770A - Applicator - Google Patents

Abstract

PURPOSE:To form a uniform coating film by allowing an application soln. to overflow the upper edge of the side wall of an application tank for a specified time when a body is not coated to supply the application soln. into the application tank. CONSTITUTION:The body 4 to be coated is dipped in the application soln. 1 contained in the application tank 2, the application soln. 1 is discharged from the inside of the application tank 2, and the body 4 is coated with the application soln. 1. When the body 4 is not coated with the application soln. 1, the application soln. 1 is allowed to overflow the upper edge 2a of the side wall of the application tank for a specified time, and the application soln. 1 is supplied into the application tank 2. As a result, a uniform coating film can be formed, and the formation of dried solid matter on the side wall of the application tank, contamination of the application soln., and formation of a defective application layer due to foreign matter can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to a coating apparatus, for example, a dip coating apparatus for coating and forming a photosensitive layer of an electrophotographic photoreceptor.

Conventional technology In recent years, organic photoreceptors with higher sensitivity and greater durability have been developed, rather than having the carrier generation function and carrier transport function separately assigned to different substances in the photosensitive layer pressure of electrophotographic photoreceptors. Attempts are being made to do so. In such so-called function-separated type electrophotographic photoreceptors, substances that exhibit each function can be selected from a wide range of materials, so it is relatively easy to produce electrophotographic photoreceptors with arbitrary characteristics. Is possible.

When coating and forming the photosensitive layer of such an electrophotographic photoreceptor, it is necessary to form a thin, uniform layer with high precision in order to maintain good sensitivity characteristics and prevent image defects such as density unevenness, thereby exhibiting good performance as a photoreceptor. It is necessary to apply a layer.

Conventionally, various coating methods such as dip coating, spray coating, spinner coating, wire bar coating, blade coating, and roller coating have been known as coating methods for the photosensitive layer of electrophotographic photoreceptors, but dip coating and spray coating are the main methods. Coating is used.

Among these, dip coating is often used to form a uniform coating on a cylindrical object (such as a conductive substrate).

FIG. 9 shows a coating device used for dip coating.

A predetermined coating liquid 1 is contained in the coating tank 32 .

During dip coating, a cylindrical conductive substrate (hereinafter sometimes referred to as a substrate drum) 4 is immersed in the coating liquid 1 with the opening 4b facing downward, and then gripped by the handle 5a of the lid 5 and removed from the substrate drum. 4 at a predetermined speed. Base drum 4
When the base drum 4 is immersed, the coating liquid 1 is removed from the hollow part 4C due to the air filling the hollow part 4C, and the liquid level 1a is lowered. Along with this, the base drum 4
In the area sandwiched between the outer circumferential surface 4e of the coating tank 32 and the inner circumferential surface 32b of the side wall of the coating tank 32, the liquid level 1a rises, and the coating liquid is applied to the outer circumferential surface 4e of the base drum up to a predetermined position, forming a coating film. It turns out.

However, in such a coating method, when the base drum 4 is pulled up by motor drive, the base drum 4 vibrates,
The coating film became non-uniform due to the influence of this vibration, resulting in uneven coating.

In order to solve this problem, a coating device as shown in FIG. 10 has been proposed.

That is, the coating liquid discharge port 17 and the coating liquid supply lower are provided on the coating tank bottom wall 32c, and the base drum 4 is fixed at a predetermined position within the coating tank 32. Next, liquid sending pump (P engineering N) 10B
As a result, the coating liquid 1 in the tank 12 is supplied from the supply lower via the filter 3, and the coating liquid level 1a is raised from the position shown by the dashed line to the position shown by the solid line. Thereafter, the drain pump (PoUT) 10A is driven to discharge the coating liquid 1 from the discharge port 17 and flow into the tank 12.

As a result, a coating film is formed on the outer peripheral surface 4e of the base drum.

According to the coating apparatus shown in FIG. 10, since the coating liquid 1 is discharged by a metering pump to form a coating film, there is no problem such as vibration caused by lifting of the base drum, and a uniform coating film can be formed.

However, in this method, after coating the base drum, until the next uncoated base drum is placed in a predetermined position in the coating tank 1, the liquid level of the coating liquid remains in a downward state as shown by the dashed line. It had been. For this reason, the coating tank side wall inner circumferential surface 32b
The coating liquid adhering to the surface is exposed to the outside air and dries, and this is deposited to form a dried substance 9. Furthermore, the dried matter 9 falls off and contaminates the coating liquid, causing foreign matter defects.

For this reason, the quality of the coating film deteriorated, and this caused the occurrence of defective products.

C1 Purpose of the Invention The purpose of the present invention is to provide a coating device that can form a uniform coating film and prevent the formation of dry solids on the side wall of the coating tank, contamination of the coating solution, and foreign matter defects. be.

29. Constitution of the Invention The present invention provides a method for discharging the coating liquid from the coating tank to the coating liquid while the coating liquid is immersed in the coating liquid stored in the coating tank. In the coating apparatus, the coating liquid overflows over the upper edge of the side wall of the coating tank for a predetermined period of time when the coating liquid is not applied to the object to be coated. The present invention will be described in detail in the following Examples.

Embodiment 1 FIGS. 1(a), 2, and 3 are schematic partial cross-sectional views showing the coating apparatus, and FIG. 1(b) corresponds to the progress of the coating process (described later). ) is the same figure (a
) is a sectional view taken along line Ib-Ib.

In this example, an outer wall 15 is provided concentrically at a constant interval around the outer periphery of the coating tank side wall 2d.
A coating liquid receiver portion 11 is provided in an area sandwiched between the outer wall 15 and the outer wall 15 .

Before the base drum 4 is immersed in the coating tank 2, it is in the state shown in FIG.

That is, the coating liquid 1 contained in the coating tank 2 uniformly passes over the upper edge 2a of the coating tank side wall in the outer circumferential direction, and flows down at a low speed while wetting the outer circumference 2e of the side wall and forming a thin film along the shape. do.

The coating liquid receiver part 11 is a coating liquid storage part that stores the coating liquid, that is, it also functions as a kind of coating liquid reservoir. It is accommodated in the lower part of section 11. Application liquid receiver is part 1
A discharge (supply) port 27A is provided at the bottom end of the coating liquid receptacle, and the coating liquid 1 once stored in the part 11 is discharged (supplied).
It is discharged from the port 27A, passes through the discharge pump IOB and the filter 3, and is supplied into the coating tank 2 from the supply (discharge) port 27B.

In this state, the base drum 4 is immersed into the coating liquid 1 to a predetermined position as shown in FIG. 1(a)K.

Next, as shown in Figure 3, stop the supply pump IOB,
Drive the discharge pump IOA. As a result, the coating liquid 1 is discharged from the supply (discharge) port 27B, and is supplied to the coating liquid receiver section 11 from the discharge (supply) port 27A via the pump IOA. As a result, the coating liquid level 1a is lowered, and a coating film is formed on the outer circumferential surface 4e of the base drum 4 up to a predetermined position.

Next, the coated base drum 4 is pulled up and discharged from the coating tank 2, and the supply pump IOB is driven 1M to supply the coating liquid 1 in the coating liquid receiver part 11 from the discharge (supply) port 27A. Discharge. Then, this coating liquid 1 is supplied (discharged) 027B via the supply pump IOB and filter 3.
The coating liquid is then supplied into the coating tank 2, and finally reaches the state shown in FIG. 2, completing one cycle of coating.

According to this example, the following effects are achieved.

(a) After lifting the base drum after coating.

Since the coating liquid is immediately supplied into the coating tank 2 to create the state shown in FIG. 2, drying of the coating liquid adhering to the inner circumferential surface 2b of the side wall of the coating tank is suppressed, and the formation of a dry substance is prevented. As a result, contamination of the coating liquid and occurrence of coating defects can be prevented.

(b) During the overflow state shown in FIGS. 1 and 2, the coating liquid that has passed through the supply pump IOB is filtered and cleaned by the filter 3, so that foreign matter does not fall into the coating liquid 1. However, since the coating liquid 1 is constantly being circulated and filtered at times other than when the coating liquid 1 is being discharged from the supply (discharge) port 27B, it is more effective in preventing foreign matter defects.

(C) When coating the base drum 4, the supply (discharge) port 27
Since the coating liquid is discharged from B by the discharge pump IOA, there is no problem of vibration caused by lifting the base drum.
A uniform coating film can be formed.

(d) Since the coating liquid flows down along the inner peripheral surface of the side wall of the coating tank, the flowing area is very large, and the coating liquid flows down while wetting the outer periphery of the side wall of the coating tank. Therefore, as a result, the falling speed of the coating liquid is very low, and the flowing down is carried out quietly, and there is no risk of entraining air bubbles.

What is particularly noteworthy is that even when the base drum is immersed, the flow rate can be reduced due to the size of the flow area, and the coating liquid can also flow down quietly.

Therefore, concave coating defects due to air bubbles do not occur, and a uniform coating film can be formed with high productivity.

(e) The coating liquid discharged from the discharge (supply) port 27A is supplied into the coating tank 2 from the supply port 27B without passing through the coating liquid storage tank (see tank 12 in FIG. 10). Therefore, there is no need to set up a separate tank, etc.
There is no need to take up extra space, and it is possible to downsize the device and reduce costs.

(f) The coating liquid receiver is provided concentrically on the outer periphery of the side wall of the coating tank, and since both are integrated, both can be controlled as one when performing temperature control, etc., which is advantageous.

(g) When non-uniform coating as described above occurs in the constituent layers of the electrophotographic photoreceptor, it appears as image unevenness, and foreign matter defects in the coating layer appear as image defects. Furthermore, if the concave defect b'-- as described in (d''l) above occurs due to air bubble entrainment, a defect occurs in which the black peta image becomes pale.

In this respect, the apparatus of this example prevents any such image defects.

Embodiment 2 FIG. 4 is a schematic partial sectional view showing a so-called overflow one-type coating device.

One car of a predetermined coating liquid is stored in the coating tank 32, and a tray 6b' is placed around the side wall 32d of the coating tank 32. The coating liquid 1 is sent out from the tank 12 by the supply pump IOB, is supplied into the coating tank 32 from the supply lower via the filter 3, and further passes over the upper edge 32a of the side wall 32d to the circumference of the coating tank 32. It overflows to the outside, is collected in a tray 5, and is discharged from a discharge port 8 into a tank 12.

In this state, the base drum 4 is immersed into the coating liquid 1 to a predetermined position.

Next, the supply pump IOB is stopped and the discharge pump 10A is driven. As a result, the coating liquid 1 is discharged from the discharge port 17 as shown by the dashed line.

It is supplied to tank 12 via discharge pump IOA. Along with this, the coating liquid level 1a decreases as shown by the dashed line, and a coating film is formed on the outer circumferential surface 48 of the base drum 4 up to a predetermined position.

Next, the base drum 4 that has been coated is pulled up and discharged from the coating tank 32, and the supply pump IOB is immediately driven. Thereby, the coating liquid 1 contained in the tank 12 is supplied into the coating tank 32 from the supply lower via the supply pump IOB and the filter 3 as shown by the arrow. and.

The button is pressed so that the coating liquid 1 overflows from the upper edge 32e of the side wall of the coating tank again, and one cycle of coating is completed.

According to the device of this example, the effects (a) to (C) and (g) above can be achieved.

Embodiment 3 FIG. 5 is a schematic partial sectional view showing still another coating device, which has almost the same configuration as the coating device in FIG. 4, and one omitted part is the same as the coating device in FIG. The same is true.

In this example, instead of separately providing the supply lower and the discharge port 17 shown in FIG. 4, a supply (discharge) port 27 that has the functions of both the lower and lower parts is provided in the bottom wall 32c of the coating tank. This further simplifies the structure of the coating device.

6 to 8 each show an example of an electrophotographic photoreceptor on which layers are formed by the coating apparatus of the present invention.

In the photoreceptor shown in FIG. 6, a first
A carrier generation layer 42 is provided as a layer, and a carrier transport layer 43 is provided as a second layer on the carrier generation layer 42. The photoreceptor shown in FIG. 7 has a carrier transport layer 43 as a first layer and a carrier generation layer 42 as a second layer stacked in this order when viewed from the conductive substrate 41 side. The photoreceptor shown in FIG. 8 has a photosensitive layer 44 having a single-layer structure containing both a carrier-generating substance and a carrier-transporting substance as a first layer.

Of course, the number and types of coating layers coated and formed by the coating apparatus of the present invention are not limited to the examples shown in FIGS. can be set freely according to the design intention.

For example, when viewed from the conductive substrate side, the first layer and the second layer are an undercoat layer and a photosensitive layer with a single layer structure, the photosensitive layer with a single layer structure, and a protective layer. The second layer and the third layer are an undercoat layer, a carrier transport layer, and a carrier generation layer, respectively.

Examples include those in which the second layer, third layer, and fourth layer are an undercoat layer, a carrier generation layer, a carrier transport layer, and a protective layer, respectively, or those in which the undercoat layer, a carrier transport layer, a carrier generation layer, and a protective layer are used. It will be done.

The undercoat layer is acrylic, methacrylic, vinyl chloride, vinyl acetate, epoxy, polyurethane, phenol, polyester, alkyd, polycarbonate, silicone, melamine, vinyl chloride/vinyl acetate copolymer. It can be formed by combining various resins such as vinyl chloride, vinyl acetate, and maleic anhydride copolymers.

The carrier generation layer is made of, for example, a monoazo dye, a disazo dye,
Azo dyes such as trisazo dyes, perylenic anhydride,
Perylene dyes such as perylenic acid imide, indigo dyes such as indigo and thioindigo, polycyclic quinones such as anthraquinone, pyrenequinone, and furapanthrones, quinacridone dyes, bisbenzimidazole dyes, indathrone dyes, and squarelillium dyes. Various known carrier-generating substances such as dyes, phthalocyanine pigments such as metal phthalocyanine and metal-free phthalocyanine, biryllium salt dyes, and eutectic complexes formed from thiapyrylium salt dyes and polycarbonate are combined with a suitable binder resin and, if necessary, a carrier transport substance. It can be formed by dissolving or dispersing it in a solvent and applying it.

The carrier transport layer may be made of an electron-accepting substance that easily transports electrons such as trinitrofluorenone or tetranitrofluorenone, or a polymer having a side chain of a heterocyclic compound such as BoIJ-N-vinylcarbazole. Various known holes such as triazole derivatives, oxadiazole derivatives, imidazole derivatives, pyrazoline derivatives, polyarylalkane derivatives, phenylenediamine derivatives, hydrazone derivatives, amino-substituted chalcone derivatives, triarylamine derivatives, carbazole derivatives, stilbene derivatives, phenothiazine derivatives, etc. It can be formed by dissolving a carrier transport material that is easy to transport in a solvent together with a suitable binder resin, coating, and drying.

Further, a photosensitive layer having a single layer structure can be formed by dissolving or dispersing the carrier generating substance as described above in a solvent together with a suitable carrier transporting substance and a binder resin, and coating the solution.

Examples of the binder resin include polycarbonate, polyester, methacrylic resin, acrylic resin, polyvinyl chloride, polyvinylidene chloride, polystyrene, polyvinyl acetate, and styrene copolymer resins (e.g., styrene-butadiene copolymer, styrene-methyl methacrylate). copolymer), acrylonitrile copolymer resin (e.g. vinylidene chloride-acrylonitrile copolymer, etc.),
Vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl acetate-maleic anhydride copolymer, silicone resin, silicone-alkyd resin, phenol resin (e.g. phenol-formaldehyde resin, m-cresol-formaldehyde resin, etc.), styrene - Film-forming polymers such as alkyd resins, poly-N-vinylcarbazole, polyvinyl butyral, and polyvinyl formal are preferred.

The protective layer contains polyurethane, polyethylene, polypropylene, etc. as the carrier transporting substance and binder resin.
Acrylic resin, methacrylic resin, vinyl chloride resin, vinyl acetate resin, epoxy resin.

It can be formed using polyester resins, phenol resins, polycarbonate resins, silicone resins, melamine resins, etc., and copolymer resins containing two or more repeating units of these resins.

Solvents used in coating and forming the carrier transport layer, carrier generation layer, etc. include acetone, methyl ethyl ketone, cyclohexanone, benzene, toluene, chlorine, chloroform, dichloromethane, 1,2-dichloroethane, and 1,1.2-) dichloroethane. , 1, 1, 2.2
-Tetrachlorxp7. I H1+ 2-trichloropropane, 1゜1.2.2-tetrachloropropane, 1
, 2.3-1- IJ dichloropane, 1.1.2-)
Dichlorobutane, 1,2.3.4-tetrachlorobutane, tetrahydrofuran, monochlorobenzene, dicumylbenzene, dioxane, methanol, ethanol, isopropanol, ethyl acetate, butyl acetate, dimethyl sulfoxide, methylcellosolve acetate, n-butylamine, diethylamine , ethylenediamine, impropaturamine, triethanolamine, triethylenediamine.

Examples include N,N-dimethylformamide and the like.

Further, as a solvent for dissolving the carrier transport substance and binder resin to form a coating liquid, a solvent that can uniformly dissolve these is selected, but a solvent with a boiling point (bp) of 80% is selected.
'C~150'C is preferable 90'C~120
℃ is more preferable. If the boiling point is less than 80° C., drying is too fast, resulting in dew condensation, which tends to cause brushing, and drying is too fast, making it impossible to level, making it difficult to obtain a smooth photosensitive layer. Furthermore, if the temperature exceeds 150'C, dripping and uneven coating are likely to occur. The specific pressure is dichloromethane, 1,
2-dichloroethane (bp = 83.5°C)% 1.
1.2-) dichloroethane (bp = 113.5°C)
, 1,4-dioxane (bp=101.3℃), Bear Zea (bp=80.1”C), Toniko7(1)p=
110.6 °C), O, m, p-xylene (bp =
(138-144°C), tetrahydrofuran, dioxane, monochlorobenzene, etc. Also, the boiling point is 80
Even if the temperature of the solvent is not in the range of .degree. C. to 150.degree. C., the boiling point can be adjusted by mixing a high boiling point solvent and a low boiling point solvent.

Further, as a solvent for forming a carrier generation layer and a photosensitive layer having a single layer structure, it is necessary to dissolve the binder resin and the carrier transport substance contained if necessary, and to transfer the carrier generation substance to a particle size of preferably 2 μm or less, more preferably 1 μm or less. A material that can be dispersed in the form of fine particles and provide a stable dispersion, and that does not unduly dissolve or swell the underlying carrier transport layer, undercoat layer, etc., if present, is selected. In particular, among the above, toluene and chloroform.

Dichloromethane, 1.2-dichloroethane, 1°1.2
-) Lichloroethane, 1.1.2.2-tetrachloroethane, tetrahydrofuran, monochlorobenzene, and dioxane are preferred solvents for both the carrier generation layer and the Φ carrier transport layer.

The coating liquid used in the present invention may contain other substances in addition to those mentioned above. For example, the inclusion of a siloxane compound has the effect of smoothing the coating surface. Examples of the siloxane compounds include dimethylpolycloxane and methylphenylvoriclogisane.

The amount added is preferably 1 to 1000011111 $m, more preferably 10 to 1000111 $m, based on the total amount of the coating liquid.

In addition, it is also possible to form a photoreceptor using the same binder resin and the same solvent, especially in the coating liquid for the carrier transport layer and the coating liquid for the carrier generation layer. In that case, the productivity and performance of the photoreceptor may be improved. This has the advantage of further improving the performance. That is,
If the same binder resin can be used, the barrier between the carrier generation layer and the carrier transport layer will be reduced, and the carriers generated during light irradiation will be smoothly injected and transported to the Φ carrier transport layer, which will improve the sensitivity characteristics, residual potential, and memory characteristics of the photoreceptor. etc. will also be improved.

Furthermore, if the same binder resin, solvent, etc. can be used in common, there is an advantage that the coating process becomes easier, more accurate, and faster.

Although the shape, material, etc. of the conductive substrate are not particularly limited, a cylindrical shape is preferably used. In addition, the materials include metal plates, metal drums, conductive polymers,
Applying a conductive thin layer made of a conductive compound such as indium oxide or a metal such as aluminum, palladium, or gold,
Those provided on a substrate such as paper or plastic film by means of vapor deposition, lamination, etc. are used.

More specifically, the following method is selected for forming the carrier generation layer and the photosensitive layer having a single layer structure.

(a) A method of applying a solution in which a carrier-generating substance is dissolved in a suitable solvent, or a solution in which a binder is added and mixed and dissolved.

(b) The carrier-generating substance is made into fine particles in a dispersion medium using a ball mill, a homomixer, etc.

A method in which a binder is added as necessary and a dispersion obtained by mixing and dispersing is applied.

In these methods, particle dispersion under the action of ultrasound allows uniform dispersion.

The coating liquid for forming photoreceptor constituent layers such as the photosensitive layer, undercoat layer, and protective layer preferably has a viscosity within the range of 5 to 500 cp (centivoise) in order to better achieve the effects of the present invention. More preferably, it is within the range of 10 to 300 cp. If the viscosity is lower than the above range, the coating film is likely to sag,
There is a tendency for the film to be thicker in the lower part than in the upper part of the drum, and if it is larger than the above range, the viscosity of the coating liquid in the coating tank tends to become non-uniform, which tends to cause uneven film thickness in the coating film.

The thickness of the carrier transport layer after coating and drying is preferably in the range of 5 to 50 μm. Further, the carrier generation layer after coating and drying usually has a thickness of 0.05 to 10 μm. In the case of a single-layer photosensitive layer, the layer thickness after coating and drying is 10~
Preferably, it is 50 μm.

The thickness of the protective layer provided on the surface of the photoreceptor is 0.01 to 1μ
b'-preferably within the range of m. Further, the thickness of the undercoat layer (or intermediate layer, barrier layer, adhesive layer, etc.) provided between the photosensitive layer and the conductive substrate is preferably within the range of 0.901 to 2 μm.

In coating and forming each photoreceptor constituent layer, coating methods such as plate coating, spray coating, spiral coating, etc. may be used in combination.

Experimental Examples Specific experimental examples will be explained below, but the present invention is not limited thereto.

<Adjustment of coating liquid> First, a coating liquid was prepared as follows.

1.2-dichloroethane (Kanto Kagakusha j!!ri 4000
During the treatment, polycarbonate (Panlite L-1250, manufactured by Kinjin Kasei Co., Ltd.) 4809 was dissolved as a binder resin, and 1.1-bis(4-N) was dissolved as a carrier transport substance.
, N-dibenzylamino-2-methylphenyl) normal butane 4809 was dissolved to prepare a coating solution for forming a carrier transport layer.

<Coating experiment> An inner diameter of 15 mm was placed around the coating tank between the example inner diameter of 120 strokes and depth of 320 mm.
An outer wall with a diameter of 0 mm and a depth of 350 mm was installed to serve as a coating tank holder, and the coating apparatus shown in FIG. 1 was obtained.

The carrier transport layer forming coating solution is stored in the coating tank, and a circulation pump (gear pump, diaphragm pump, etc.)
was used to circulate at 2000 cc/min. An aluminum cylindrical conductive base drum (cylinder) with an outer diameter of 80 mmφ and a length of 300 mm is immersed in this device, and then the coating liquid is drawn out from the bottom of the coating tank using a metering pump (gear pump, diaphragm pump, etc.). , and supplied to the coating liquid receiver. At this time, apply 300ml/
The substrate drum was kept fixed in the coating tank. and.

When the base drum that has been coated is pulled up from the coating tank,
Immediately, the coating tank was filled with the coating liquid using the supply pump, and the tank was again circulated at 2000 cc/min.

The above operation was repeated 100 times to coat 100 base drums.

As a result, two base drums were found to have coating defects due to adhesion of foreign matter. Further, the coating film of the gear transport layer formed by coating was uniform, and no concave defects caused by entrainment of air bubbles were observed.

Regarding the uniformity of the coating film and the presence or absence of concave defects.

It was inspected by a sensory test using a visual button.

Comparative Example A coating experiment was conducted using the coating apparatus shown in FIG. 10, with the dimensions of the coating tank the same as in the Examples, and under the same conditions as described in the Examples.

However, after the base drum is lifted from the coating tank.

The carrier transport layer forming coating liquid was left to be discharged from the coating tank, and then the uncoated base drum was placed and fixed in the coating tank, and then the coating liquid was supplied into the coating tank.

As a result, 15 base drums were found to have coating defects due to adhesion of foreign matter.

Modifications Although the present invention has been illustrated above, the embodiments of the present invention are not limited to those described above, and various modifications can be made based on the technical idea of the present invention.

For example, the coating liquid receiver does not need to be provided concentrically around the outer circumference of the side wall of the coating tank as shown in Fig. 1;
The shape etc. can be changed in various ways. For example, as shown in FIG. 1(b), the shape may be made larger (bulged) in a certain direction, and the swollen portion may mainly have a function as a coating liquid storage section.

In addition, there are no special restrictions on the size, shape, material, etc. of the coating tank.

When lifting the coated object from the coating tank after coating,
The coating liquid may be supplied into the coating tank at the same time as the object to be coated is pulled up.

Number of feed pumps, discharge pumps, and filters.

Abilities etc. can be changed in various ways. In the example shown in FIG. 1, it is possible to provide a tank for accommodating the coating liquid discharged from the coating tank separately from the coating liquid receiver.The present invention can be applied to various coating apparatuses.

According to the coating apparatus of the present invention, when the coating liquid is not applied to the object to be coated, the coating liquid is applied by overflowing over the upper edge of the side wall of the coating tank for a predetermined period of time. Since the liquid is supplied into the coating tank, drying of the coating liquid adhering to the side wall of the coating tank can be prevented, and formation of dry matter of the coating liquid, contamination of the coating liquid, and foreign matter defects in the coating layer can be prevented.

Further, since the coating liquid is applied to the object to be coated by discharging the coating liquid from the coating tank, there is no need to pull up the object to be coated during coating. Therefore.

It is possible to eliminate the influence of vibrations associated with lifting the object to be coated, and it is possible to form a uniform coating layer.

[Brief explanation of the drawing]

Figures 1 to 8 show examples, and Figure 1 (
a) is a schematic partial sectional view showing the coating device; The figure (b) is a sectional view taken along the line Ib-Ib of the figure (a). FIG. 2 is a schematic partial sectional view showing the state before the base drum is immersed in the coating device. FIG. 3 is a schematic partial sectional view showing a state where the coating liquid is being discharged from the coating tank, and FIG. 4 is a schematic partial sectional view showing another coating device. FIG. 5 is a schematic partial cross-sectional view showing another coating apparatus, and FIGS. 6, 7, and 8 are partial cross-sectional views each showing an example of an electrophotographic photoreceptor manufactured by the coating apparatus of the present invention. It is. FIG. 9 is a partial sectional view showing a conventional coating device. FIG. 10 is a schematic partial sectional view showing another conventional coating device. In addition, in the reference numerals shown in the drawings. 1...Coating liquid 2.32...Coating tank 2a, 32a...Coating tank side wall upper part 3.
......Filter 4...Cylindrical conductive base drum 7...
......Coating liquid outlet 10A...Discharge pump 10B...Supply pump 11...Coating liquid receiver 15... ......Coating device outer wall 17...Coating liquid supply port 27A...Coating liquid discharge port (supply port) 27
B: Coating liquid supply port (discharge port).

Claims (1)

[Claims] 1. A coating device that applies the coating liquid to the object by discharging the coating liquid from the coating tank while the object is immersed in the coating liquid stored in the coating tank, When the coating liquid is not applied to the object to be coated, the coating liquid is supplied into the coating tank in such a manner that the coating liquid overflows over the upper edge of the side wall of the coating tank for a predetermined period of time. A coating device characterized in that it is configured to