JP2000189885A - Immersion coating method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the product acceptance percentage by preventing the generation of liquid scattering and reducing a washing residue. SOLUTION: A support member 25 is fitted to one opening of a cylindrical substrate 21 to close the substrate 21, the substrate 21 is immersed in a coating liquid 23 from the end part side of the other opening of the substrate 21. When the substrate 21 is removed from the liquid 23, immediately before the end part of the other opening of the substrate 21 being removed from the surface of the liquid 23, at a prescribed pressurization position apart from the ends part of the other opening of the substrate 21, the inside of the substrate 21 is pressurized by a prescribed pressurization force.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dip coating method, and more particularly, to a photosensitive material on an outer peripheral surface of a cylindrical substrate for an electrophotographic photosensitive member such as an OPC photosensitive drum used for a PPC copying machine, a laser beam planter, or the like. To a method for dip-coating a coating solution containing

[0002]

2. Description of the Related Art Conventionally, as a method of applying a photosensitive layer of an electrophotographic photosensitive member, there are known coating methods such as dip coating, spray coating, and nozzle coating. Among them, uniform coating is applied to a cylindrical object to be coated. A dip coating method is frequently used as a forming method. This dip coating method is to form a coating film on the outer peripheral surface of an object to be coated by immersing the object to be coated in a coating solution, and is generally widely used. However, since both ends are open, there is a problem in that the coating liquid penetrates into the inside of the base and a coating film is formed on the inner peripheral surface of the base. In order to solve this problem, a method has been proposed in which a lid is attached to the lower end of the base to prevent penetration of the coating liquid into the inside, or air is trapped inside the base to prevent the penetration of the coating liquid to the outside of the base by air pressure. I have. However, in the latter case, the volume of the air inside the base increases due to the evaporation of the solvent, and the air is released as bubbles to the outside of the base, and the bubbles burst on the surface of the coating liquid and disturb the coating surface. There is a problem of causing it. In order to prevent the generation of such bubbles, a method of extracting gas such as air trapped inside the substrate is disclosed in JP-B-62-4187 and JP-A-63-77567.
And methods for adjusting the pressure inside the substrate and the outside air pressure are disclosed in JP-A-1-123664 and JP-B-4-68989. JP-A-8-89879 relates to an improvement of a dip coating method in which a cylindrical substrate is pulled up from a coating solution. Most of the substrate is pulled up at a high speed, and the remaining portion is pulled up at a low speed. A method for manufacturing a cylindrical substrate having a coating film free from defects such as splashing from the coating liquid surface is disclosed. Further, JP-A-7-136576 discloses a method for forming a coating on the outer peripheral surface of a substrate by immersing a cylindrical substrate from a coating solution. A dip coating method is disclosed in which bath medium vapor of a coating liquid is blown to prevent generation of coating defects due to bubbles.

[0003]

FIG. 6 shows an outline of the steps of the conventional dip coating method. As shown in the figure, it is shown that a coating film is formed on the outer peripheral surface of the cylindrical substrate by following the steps of A → B → C → D → E. A in the figure shows a state in which the cylindrical substrate having the inside of the substrate hermetically sealed is immersed, and the coating liquid slightly penetrates into the inside of the substrate by the pressure of water pressure. B in the figure shows a state in which the base is being pulled up, and the intrusion of the liquid inside the base is reduced by a decrease in water pressure due to the pulling up of the base. C in FIG.
Shows a cylindrical substrate immediately before the lower end of the substrate reaches the coating liquid surface. In this state, the coating liquid has penetrated into the substrate by surface tension. D in the figure shows a state immediately after the cylindrical substrate has left the surface of the coating liquid. The coating liquid is pulled to the lower end of the substrate by surface tension, and a difference between the external pressure and the internal pressure is generated.
E in the figure shows a state in which the substrate is further pulled up, and the application liquid pulled in D in the figure separates from the substrate and is about to drop to the surface of the application liquid. Here, the state from D to E in FIG. 6 is shown in FIG. 7, and will be described in detail with reference to FIG. 7. FIG. 7A shows the state immediately after the cylindrical substrate has left the coating liquid surface. As can be seen from the figure, a liquid film is formed at the lower end of the substrate due to the coating liquid dripping from above the outer periphery of the substrate and the surface tension of the coating liquid surface. Then, as the base is pulled up, the space inside the base is pulled and the volume expands, so that when the inside of the base is in a closed state, the pressure inside the base decreases. As a result, a pressure difference is generated between the inside and the outside of the base, so that the coating liquid film is narrowed inward as shown in FIG. Further, when the base is lifted, FIG.
As shown in (c), the film of the coating liquid is broken and the liquid scatters inward and adheres to the inner peripheral surface of the substrate.

As described above, in the above-mentioned conventional method, when the substrate is pulled up from the coating solution, the coating solution slightly entering the inside of the substrate falls onto the surface of the coating solution and splashes. Therefore, when such liquid splash occurs, a coating film is formed on the inner peripheral surface of the base, so that the area and location at the time of edge cleaning become large, the wiping work becomes complicated, and the entire cleaning takes time. There are problems such as. In addition, the coating liquid adhered to the inner peripheral surface of the substrate is difficult to dry, and cleaning scum (including the liquid) generated by edge cleaning adheres to a pallet for transporting the substrate, thereby causing a problem that the pallet is stained. There is also a problem. Further, since the coating liquid and the cleaning scum (including the liquid) adhere to the pallet, the pallet needs to be cleaned with a solvent, and the coating liquid adheres to the inner peripheral surface and the pallet. There is a problem.

[0005] Further, in the conventional method in which most of the cylindrical substrate is pulled up from the coating liquid at a high speed and the remaining portion is pulled up at a low speed, the latter half of the pulling-up step in which liquid splash is likely to occur as described above. Therefore, there is a problem that the possibility that the vapor inside the cylindrical substrate leaks to the outside of the substrate and splashes the liquid to disturb the coating film cannot be avoided. Furthermore, in the conventional method of blowing the bath medium vapor of the coating liquid into the inside of the substrate, it is necessary to stop at the liquid level when coating in multiple layers, and the layer already coated on the substrate is exposed to the vapor of the coating liquid. There is a problem that the occurrence of the dissolution phenomenon may disturb the coating film and cause uneven coating.

An object of the present invention is to solve these problems, and an object of the present invention is to provide a dip coating method capable of preventing generation of liquid splash and improving a non-defective product rate by reducing a cleaning residue. .

[0007]

In order to solve the above-mentioned problems, the present invention provides a dip coating method for forming a coating film on the outer peripheral surface of a cylindrical substrate by immersing the cylindrical substrate in a coating solution. Attach the support member to one opening of the base, close it, immerse it in the coating liquid from the end of the other opening of the cylindrical base, and pull up the cylindrical base when the end of the other opening of the cylindrical base is coated with the coating liquid. This is characterized in that the inside of the cylindrical substrate is pressurized with a predetermined pressing force at a predetermined pressing position from the end of the other opening of the cylindrical substrate immediately before leaving the liquid surface. Therefore, since the inside of the substrate is separated from the liquid surface in a pressurized state, it is possible to prevent the application liquid from entering the inside of the substrate, to prevent the liquid from splashing into the inner peripheral surface of the substrate, and to reduce the amount of cleaning residue. The rate can be improved.

[0008] The predetermined pressure is 9.8 × 10 ^{-7 to} 4.9 ×
By setting the pressure to 10 ⁻⁶ Pa, generation of liquid splash on the outer peripheral surface of the base can be prevented.

Further, the pressing position is determined as follows: upper limit of pressing position = (coating speed) × (coating coefficient) × 0.33, lower limit of pressing position =
(Coating rate) × (coating coefficient) × 0.21 ((coating coefficient) = {(radius of inner diameter of coating tank) ² − (radius of outer diameter of cylindrical base) ² } / (of cylindrical base By setting the radius within the range determined by the upper limit and the lower limit determined by ( ² )), splashing of the liquid on the inner peripheral surface and the outer peripheral surface can be prevented.

Further, the predetermined pressing force is determined as follows:
6.0 × 10 ^-9 × (radius of outer diameter of cylindrical substrate) ² , lower limit of pressing force = 3.0 × 10 ^-9 × (radius of outer diameter of cylindrical substrate) ² By setting it within the range determined by the lower limit, it is possible to appropriately prevent cylindrical substrates having different diameters from splashing the liquid on the inner peripheral surface and the outer peripheral surface.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In a dip coating method in which a cylindrical substrate is immersed in a coating solution to form a coating film on the outer peripheral surface of the cylindrical substrate, a supporting member is attached to one opening of the cylindrical substrate, and the cylindrical member is closed. When the cylindrical substrate is lifted up by dipping in the coating liquid from the end of the other opening of the cylindrical substrate and immediately before the end of the other opening of the cylindrical substrate separates from the liquid surface of the coating liquid and the other end of the cylindrical substrate The inside of the cylindrical substrate is pressurized with a predetermined pressing force at a predetermined pressing position from the end of the opening.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view showing a configuration of a dip coating apparatus according to one embodiment of the present invention. In the figure, the dip coating apparatus in this embodiment includes a cylindrical substrate 1, a coating tank lid 2, a receiving tray 3, a coating tank lid opening 4, a solvent vapor layer 5, a coating tank 6, a return pipe 7, a preliminary tank 8, Coating liquids 9 and 13;
Filter 11, supply port 12, return liquid 14, coating liquid level 1
5, including the side wall 16 and the support 17.
The coating liquid 13 is a coating liquid that overflows the upper edge of the side wall 16. More specifically, a predetermined coating liquid 9 is stored in the coating tank 6, and the tray 3 is provided around the side wall 16 of the coating tank 6. The coating liquid 9 is sent out from the preliminary tank 8 by the liquid feed pump 10 and supplied through the filter 11 from the supply port 12 into the coating tank 6 as shown by the arrow B, and further over the upper edge of the side wall 16. It overflows in the circumferential direction of the coating tank 6, is collected in the tray 3, and is returned to the return pipe 7.
It is further discharged to the preliminary tank 8. After the liquid supply pump 10 is stopped and the coating tank lid 2 is fully opened, the cylindrical substrate 1 starts immersion, passes through the vapor layer 5 and enters the coating liquid surface 15. Cylindrical substrate 1
After the lower end of the substrate enters the coating liquid 9, the substrate is immersed in the direction shown by the arrow A while changing the speed.

The cylindrical substrate in the electrophotographic photosensitive member used in the present invention has a volume resistance of 1.0 × 10 ¹⁰
It shows conductivity of Ωcm or less, for example, aluminum, nickel, chromium, copper, tin oxide, indium oxide or the like is vapor-deposited on a sheet-like or seamless belt-like plastic film and formed into an endless belt, nickel, iron, Seamless belts made of beryllium-copper alloy, aluminum, nickel-cobalt alloy, stainless steel, etc. I, I.I. I. Tubes that have been surface-treated by cutting, superfinishing, polishing, or the like after being formed into a tube by a method such as extrusion or drawing can be used, but the present invention is not limited thereto.

In the electrophotographic photoreceptor used in the present invention, an undercoat layer can be provided between the cylindrical conductive substrate and the photosensitive layer. The undercoat layer serves as an adhesive layer for preventing charge injection from the conductive substrate into the photosensitive layer in the photosensitive layer having a laminated structure during charging, and for integrally bonding and holding the photosensitive layer to the conductive substrate. It has an action or an action of preventing light reflected from the conductive support. The undercoat layer generally contains a resin as a main component, but considering that these resins are coated thereon with a photosensitive layer using a solvent,
It is desirable that the resin has high resistance to dissolution in general organic solvents. Such resins include polyvinyl alcohol, casein, water-soluble resins such as sodium polyacrylate, copolymerized nylon, alcohol-soluble resins such as methoxymethylated nylon, polyurethane, melamine resin, alkyd-melamine resin, epoxy resin, and the like. Examples include, but are not limited to, curable resins having a three-dimensional network structure.

Further, fine powder of a metal oxide exemplified by titanium oxide, silica, alumina, zirconium oxide, tin oxide, indium oxide or the like may be added to the undercoat layer in order to prevent moire and reduce residual potential. good. These undercoat layers can be formed using an appropriate solvent and a coating method as in the above-described photosensitive layer.

Further, as the undercoat layer of the present invention, a metal oxide layer formed by using a silane coupling agent, a titanium coupling agent, a chromium coupling agent or the like, for example, by a sol-gel method is also useful. In addition to this, the undercoat layer of the present invention is provided with Al ₂ O ₃ by anodic oxidation, an organic substance such as polyparaxylylene (parene), and Si.
Those provided with an inorganic substance such as O, SnO ₂ , TiO ₂ , ITO, CeO ₂ by a vacuum thin film manufacturing method can also be used favorably.
The thickness of the undercoat layer is suitably from 3 to 7 μm.

Further, the charge generation layer of the present invention is a layer containing a charge generation material as a main component. Inorganic and organic materials are used for the charge generation material, and as typical examples, monoazo pigments, disazo pigments, trisazo pigments, perylene pigments,
Perinone pigments, quinacridone pigments, quinone condensed polycyclic chemicals, squaric acid dyes, phthalocyanine pigments, naphthalocyanine pigments, azulhenium salt dyes,
Examples include, but are not limited to, selenium, selenium-tellurium, selenium-arsenic alloy, amorphous silicon, and the like.

The charge generation material of the present invention may be used alone or in combination of two or more. The charge generation layer is dispersed by a ball mill, an attritor, a sand mill, or the like using an appropriate solvent such as tetrahydrofuran, cyclohexanone, dioxane, 2-butanone, or dichloroethane, together with a binder resin appropriately using a charge generation material, and applying a dispersion. Can be formed. At this time, the charge generating substance has a volume average particle diameter of 5 μm or less, preferably 2 μm or less.
It is effective to set the particle size to not more than m, most preferably not more than 0.5 μm. The coating can be performed by a dip coating method, a spray coating method, a bead coating method, or the like. In addition, as a binder resin used as appropriate, polyamide, polyurethane, polyester, epoxy resin, polyketone, polycarbonate, silicone resin, acrylic resin, polyvinyl butyral, polyvinyl formal,
Examples thereof include polyvinyl ketone, polystyrene, and polyacrylamide. The amount of the binder resin appropriately used is 0 to 1 part by weight of the charge generating material.
2 parts by weight are suitable. The thickness of the charge generation layer used in the present invention is generally 0.1 to 5 μm or less, preferably 0.2 to 5 μm.
2 μm is appropriate.

Further, the charge transport layer in the electrophotographic photoreceptor of the present invention is formed by including a charge transport substance in a suitable binder. Oxazoazole derivatives such as 2,5-bis (p-diethylaminophenyl) -1,3,4-oxadiazole, 1,3,3
5-triphenyl-pyrazoline, 1- [pyridyl-
(2)]-3- (p-Diethylaminostyryl) -5-
Pyrazoline derivatives such as (p-diethylaminophenyl) pyrazoline; aromatic tertiary amino compounds such as triphenylamine, styryltriphenylamine and dibenzylaniline; N, N′-diphenyl-N, N′-bis (3- Methylphenyl) -1,1-biphenyl-4,
Aromatic tertiary diamino compounds such as 4'-diamine, 3
-(4'-dimethylaminophenyl) -5,6-di-
1,2,4-triazine derivatives such as (4′-methoxyphenyl) -1,2,4-triazine, hydrazone derivatives such as 4-diethylaminobenzaldehyde-1,1-diphenylhydrazone, 2-phenyl-4-styryl- Quinazoline derivatives such as quinzoline; benzofuran derivatives such as 6-hydroxy-2,3-di (p-methoxyphenyl) -benzofuran; α-stilbenes such as p- (2,2-diphenylvinyl) -N and N-diphenylaniline Derivative, “Journal of Imagin
g Science "29: 7-10 (1985), carbazole derivatives such as N-ethylcarbazole, poly-N-vinylcarbazole such as poly-N-vinylcarbazole and derivatives thereof, and poly-γ. -Carbazolylethyl glutanate and its derivatives, and also a known charge transporting substance such as pyrene, polyvinyl pyrene, polyvinyl anthracene, polyvinyl acridine, poly-9-biphenylanthracene, pyrene-formaldehyde resin, ethyl carbazole formaldehyde resin. But not limited to these. These charge transporting substances can be used alone or in combination of two or more.

As the binder resin in the charge transport layer, polycarbonate resin, polyester resin, methacrylic resin, acrylic resin, polyvinyl chloride resin, polyvinylidene chloride resin, polystyrene resin, polyvinyl acetate resin, butylene-butadiene copolymer , Vinylidene chloride-acrylonitrile copolymer, vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl acetate-maleic anhydride copolymer, silicone resin, silicone-alkyd resin, phenol-formaldehyde resin, styrene-alkyd resin, poly A known resin such as -N vinylcarbazole can be used, but is not limited thereto. These binder resins can be used alone or in combination of two or more.

In the present invention, a plasticizer or a leveling agent may be added to the charge transport layer. As the plasticizer, those used as general plasticizers for general resins such as dibutyl phthalate and dioctyl phthalate can be used as they are, and the amount of the plasticizer is suitably about 0 to 30% by weight based on the binder resin. As the revaging agent, silicone oils such as dimethyl silicone oil and methyl phenyl silicone oil, and polymers or oligomers having a perfluoroalkyl group in the side chain are used in an amount of 0 to 1% by weight based on the binder resin. Is appropriate.

Further, if necessary, a protective layer may be provided on the charge transport layer. This protective layer is used to prevent the charge transport layer from being chemically altered during charging of the photosensitive layer having a laminated structure, and to improve the mechanical strength of the photosensitive layer.
Further, the above-described charge transporting material may be added to the protective layer. As the binder resin used for the protective layer, known resins such as polyamide resin, polyurethane resin polyester resin, epoxy resin, polyketone resin, polycarbonate, polyvinyl ketone resin, polystyrene, and polyacrylamide resin can be used. It is not limited to these.

Further, the protective layer must be configured so as not to substantially hinder the passage of light used for image exposure.
Materials used for this include ABC resin, ACS resin, olefin-vinyl monomer copolymer, chlorinated polyether, allyl resin, phenolic resin, polyacetal, polyamide, polyamideimide, polyacrylate, polyallyl sulfone, polybutylene, Polybutylene terephthalate, polyimide, acrylic resin, polymethylpentene, polypropylene, polyphenylene oxide, polysulfone, AS resin, AB resin, BS resin, polyurethane, polyvinyl chloride, polyvinyl chloride, polyvinylidene chloride, polyvinylidene chloride, epoxy resin, etc. Resins. In the protective layer, for the purpose of improving the abrasion resistance, a fluororesin such as polytetrafluoroethylene, a silicone resin and titanium oxide to these resins,
A dispersion of an inorganic material such as tin oxide and potassium titanate can be added. As a method for forming the protective layer, a normal coating method is employed. The thickness of the protective layer used in the present invention is 0.5 to 20 μm, preferably 1 to 10 μm.
μm is appropriate. In addition to the above, known materials such as iC and a-SiC formed by a vacuum thin film manufacturing method can be used as the protective layer.

Further, in the present invention, another intermediate layer can be provided between the photosensitive layer and the protective layer. The intermediate layer generally uses a binder resin as a main component. Examples of these resins include polyamide, alcohol-soluble nylon, water-soluble polyvinyl butyral, polyvinyl butyral, and polyvinyl alcohol. As a method for forming the intermediate layer, a normal coating method is employed as described above. The thickness of the intermediate layer is suitably about 0.05 to 2 μm.

FIG. 2 is a view schematically showing a coating step in the dip coating method according to the present invention. This shows that a coating film is formed on the outer peripheral surface of the cylindrical substrate by following the steps of A → B → C → D → E. In the figure, 21 is a cylindrical substrate, 22 is a coating tank, 23 is a coating liquid, 24 is a support member, and 25 is an air supply pipe. A in the figure shows a state in which the cylindrical substrate 21 is immersed in the coating tank 22 as shown in FIG. 1, and at this time, the coating liquid 23 has slightly penetrated into the substrate by water pressure. B in the same figure shows a state in which the base is pulled up. C in the figure shows the state of the cylindrical substrate 21 immediately before the lower end of the substrate reaches the coating liquid level. At this time, air is blown into the internal space of the cylindrical substrate 21 from the air supply pipe 25 to pressurize the inside of the substrate. This prevents the liquid film generated when the substrate comes out of the coating liquid surface from being drawn inward. D in the figure shows a state at the moment when the cylindrical substrate 21 has left the coating liquid surface. Since air is supplied from the air supply pipe 25 to the inside of the substrate, even if the coating liquid film ruptures, the substrate is scattered and scattered. It does not adhere inside. After the substrate comes out of the coating solution 23, the supply of air to the inside of the substrate is stopped, as shown at E in FIG. In addition, in the dip coating apparatus of FIG. 1, the liquid feed pump 10 starts operating again, and the circulation of the coating liquid starts,
The coating tank lid 2 closes and seals the coating tank 6.

Next, the steps of forming each layer will be described, and the steps will be described in accordance with the present embodiment.

1. Formation of Undercoat Layer The following materials were dissolved to prepare an undercoat layer coating solution. Soluble nylon 5 parts by weight (Alamine CM-8000, manufactured by Toray) Methanol 95 parts by weight The undercoat layer coating solution prepared as described above is dip-coated on a nickel cylindrical substrate having an outer diameter of 80 mm and a length of 410 mm. After drying at 100 ° C. for 10 minutes, an undercoat layer having a thickness of 0.3 μm was formed.

2. Formation of charge generation layer Charge generation agent represented by the following structural formula 1 10 parts by weight Polyvinyl butyral 7 parts by weight Tetrahydrolan 145 parts by weight

Each of these solutions was placed in a ball mill and milled for 72 hours. Further, 200 parts by weight of cyclohexanone was added and dispersed for 1 hour. The liquid after completion of the dispersion was further diluted and adjusted with cyclohexanone to obtain a charge generating layer coating liquid. The nickel cylindrical substrate having the undercoat layer formed thereon was applied by dip coating under the following conditions, and dried at 100 ° C. for 10 minutes to form a 0.1 μm-thick charge generating layer.

[0030]

Embedded image

3. Coating of charge transport layer Nickel cylindrical substrate coated with undercoat layer as described in 1 above
The body is immersed in the coating solution of the above 2 at a speed of 30 mm / s.
Pickled. After standing still for 15 seconds, at a speed of 3.89 mm / s
Raised. Immediately before the lower edge of the substrate leaves the coating liquid level,
Air was sent inside and pressurized. The pressurized air pressure is
4.9 × 10^-6Pa was applied to 10 coats. Coating
The liquid splash condition on the inner and outer peripheral surfaces of the sample
At this time, no liquid splash was generated in all 10 tubes. Therefore, appropriate
The range of the applied pressure is 9.8 × 10^-7 ~ 4.9 × 10^-6P
a. Note that the lower limit is not guaranteed due to the limitations of the machine.
The value is within the recognized range. With these results
The theoretical expression of the preferred pressure is given by the following equation.
Can be expressed as

Upper limit of applied pressure = 6.0 × 10 ⁻⁹ × (radius of outer diameter of cylindrical base) ² Lower limit of applied pressure = 3.0 × 10 ⁻⁹ × (radius of outer diameter of cylindrical base) ^Two

Next, an example according to the present invention and a comparative example not according to the present invention will be described. As a comparative example 1, a nickel cylindrical substrate coated with an undercoat layer is removed until the lower end of the substrate leaves the coating liquid surface. It was pulled up at a speed of .89 mm / s as it was and 10 pieces were applied. As described above, according to Comparative Example 1 not according to the present invention, the state of liquid splashing on the inner and outer peripheral surfaces of the applied sample was confirmed. Has occurred.

Next, in the coating and dipping method of the present invention,
Sends air into the base just before the lower end leaves the coating liquid surface
Considering the magnitude of the applied pressure,
3A, the lower end of the substrate may be at the coating liquid level as shown in FIG.
The liquid inside the substrate is released to the outside before leaving
The air blows out and liquid splash is generated on the outer peripheral surface. one
On the other hand, when the pressing force is small, as shown in FIG.
The coating liquid remains inside the substrate even when the
The conventional problem cannot be solved, that is, the liquid
Splashes occur. For example, the pressure to pressurize as Comparative Example 2
Is 4.9 × 10^-Five When applying 10 pieces as Pa, apply
Check the liquid splash condition on the inner and outer peripheral surfaces of the sample
As a result, no liquid splash was observed on the inner peripheral surface,
The liquid splash on the outer peripheral surface was generated in all ten tubes.

Considering the pressure application position, if the pressure application start position is early as shown in FIG. 3C, the lower end of the base may be separated from the coating liquid surface as shown in FIG. 3D. The liquid remains inside the substrate, and liquid splashes are generated on the inner peripheral surface.

Further, the results of experiments on the state of generation of liquid splashes when the pressure and the coating speed are varied are shown below. In the experiment, a nickel cylindrical substrate having an outer diameter of 80 mm was immersed and coated in a coating tank having an inner diameter of 120 mm at a different coating speed, the pressure position was fixed at 1.3 mm, and the pressure was 2.0.
The dip coating according to the present invention was performed at a coating speed of 3 to 15 mm / s at a level of × 10 ^-6 , 3.9 × 10 ^-6 , 5.9 × 10 ^-6 Pa. FIG. 4 shows the results. In the figure, ○ indicates that liquid splash did not occur, X indicates that liquid splash occurred and affected the outer peripheral surface of the cylindrical base, and Δ indicates that liquid splash occurred and the cylinder did not. It indicates that the influence has been exerted on the inner peripheral surface of the substrate. As can be seen from the results shown in FIG. 4, when the pressure was 2.0 × 10 ⁻⁶ Pa, the liquid did not splash only when the coating speed was 5 mm / s, 7 mm / s, and 9 mm / s. . Further, the pressing force is 3.9 × 10 ^−6.
When Pa, the coating speed is 7 mm / s, 9 mm / s, 1
Liquid splash did not occur only at 1 mm / s. Further, when the pressing force is 5.9 × 10 ⁻⁶ Pa, the coating speed is 9 mm.
No liquid splash was generated only at the speeds of / mm and 11 mm / s. The same applies to the overflow-type dip coating method, since only the coating speed is different. After all, it was found that the coating speed of 9 mm / s was the most appropriate at the three pressing forces. With such a result, a preferable pressing position can be theoretically expressed by the following equation.

Upper limit of pressing position = (coating speed) × 0.18 Lower limit of pressing position = (coating speed) × 0.12

The coating speed has a margin of ± 2 mm / s.

Next, FIG. 5 shows the results of an experiment on the state of occurrence of liquid splashing when the coating speed and the pressing position were changed by various types. Note that the pressure is 3.9 × 10 ⁻⁶ Pa. In the experiment, a nickel cylindrical substrate with an outer diameter of 80 mm was
Was subjected to dip coating at a different coating speed.

As can be seen from the figure, the coating speed is 13 m
At m / s, liquid splash did not occur on the inner peripheral surface and the outer peripheral surface when B and C, that is, when the pressing position was 1.8 mm and 2.3 mm. In addition, when the pressing position was 1.3 mm or less, which is the condition of A, liquid splash occurred on the inner peripheral surface. When the coating speed is 7 mm / s, D, that is, the pressing position is 1.3 mm
No liquid splash was generated on the inner and outer peripheral surfaces.
That is, when the pressing position was 1.8 or more, liquid splash occurred on the outer peripheral surface. From the pressure positions under the conditions B, C, and D, which are the results of these experiments, a preferable pressure position range can be theoretically expressed by the following equation.

Upper limit of pressing position = (coating speed) × (coating coefficient) × 0.33 Lower limit of pressing position = (coating speed) × (coating coefficient) × 0.2
1

The coating coefficient is {(radius of inner diameter of coating tank) ² − (radius of outer diameter of cylindrical substrate) ² } / (radius of outer diameter of cylindrical substrate) ² .

Therefore, the preferable pressing position range at a coating speed of 13 mm / s is 1.5 to 2.4 mm, and the preferable pressing position range at a coating speed of 7 mm / s is 0.8 to 2.4 mm.
It was found to be 1.3 mm.

It should be noted that the present invention is not limited to the above-described embodiment, and various modifications and substitutions can be made within the scope of the claims.

[0045]

As described above, according to the present invention,
In a dip coating method for immersing a cylindrical substrate in a coating solution to form a coating film on the outer peripheral surface of the cylindrical substrate, a support member is attached to one opening of the cylindrical substrate, closed, and the other opening of the cylindrical substrate is closed. Immersed in the coating liquid from the end side, and when the cylindrical substrate is pulled up, just before the end of the other opening of the cylindrical substrate separates from the liquid surface of the coating liquid and from the end of the other opening of the cylindrical substrate It is characterized in that the inside of the cylindrical substrate is pressurized with a predetermined pressing force at the predetermined pressing position. Therefore, since the inside of the substrate is separated from the liquid surface in a pressurized state, it is possible to prevent the application liquid from entering the inside of the substrate, to prevent the liquid from splashing into the inner peripheral surface of the substrate, and to reduce the amount of cleaning residue. The rate can be improved.

The predetermined pressure is 9.8 × 10 ^{−7 to} 4.9 ×.
By setting the pressure to 10 ⁻⁶ Pa, generation of liquid splash on the outer peripheral surface of the base can be prevented.

Further, the pressing position is determined as follows: pressing position upper limit = (coating speed) × (coating coefficient) × 0.33, pressing position lower limit =
(Coating rate) × (coating coefficient) × 0.21 ((coating coefficient) = {(radius of inner diameter of coating tank) ² − (radius of outer diameter of cylindrical base) ² } / (of cylindrical base By setting the radius within the range determined by the upper limit and the lower limit determined by ( ² )), splashing of the liquid on the inner peripheral surface and the outer peripheral surface can be prevented.

The predetermined pressing force is determined by the following equation:
6.0 × 10 ^-9 × (radius of outer diameter of cylindrical substrate) ² , lower limit of pressing force = 3.0 × 10 ^-9 × (radius of outer diameter of cylindrical substrate) ² By setting it within the range determined by the lower limit, it is possible to appropriately prevent cylindrical substrates having different diameters from splashing the liquid on the inner peripheral surface and the outer peripheral surface.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a configuration of a dip coating apparatus according to the present invention.

FIG. 2 is a view showing a state of a process of a dip coating method according to one embodiment of the present invention.

FIG. 3 is a diagram illustrating a state in which the pressure is large and the pressing start position is fast in the coating and dipping method of the present embodiment.

FIG. 4 is a view showing an experimental result of a state of generation of liquid splash when a pressing force and a coating speed are changed in the present embodiment.

FIG. 5 is a diagram showing an experimental result of a state of occurrence of liquid splash when a coating speed and a pressing position are changed in the present embodiment.

FIG. 6 is a view showing a state of a process according to a conventional dip coating method.

FIG. 7 is a view showing a state of a phenomenon of generation of a conventional liquid splash.

[Explanation of symbols]

 1, 21 Cylindrical substrate 2 Coating tank lid 3 Receiving tray 4 Coating tank lid opening 5 Solvent vapor layer 6, 22 Coating tank 7 Return pipe 8 Preliminary tank 9, 13, 23 Coating liquid 10 Liquid feed pump 11 Filter 12 Supply port 14 Return liquid 15 Application liquid surface 16 Side wall 24 Support member 25 Air supply pipe

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Hisayoshi Goto 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd. (72) Inventor Kenichi Usami 1-3-6 Nakamagome, Ota-ku, Tokyo F-term in Ricoh Co., Ltd. (reference) 2H068 EA16 4D075 AB37 AB55 AB56 CA48 DA15 DC27 EA45

Claims (4)

[Claims] 1. A dip coating method in which a cylindrical substrate is immersed in a coating solution to form a coating film on an outer peripheral surface of the cylindrical substrate, wherein a support member is attached to one opening of the cylindrical substrate and closed. The cylindrical substrate is immersed in the coating liquid from the end of the other opening of the cylindrical substrate, and when the cylindrical substrate is pulled up, immediately before the end of the other opening of the cylindrical substrate separates from the liquid surface of the coating liquid. A dip coating method, wherein the inside of the cylindrical substrate is pressurized with a predetermined pressing force at a predetermined pressing position from an end of the other opening of the cylindrical substrate. 2. The method according to claim 1, wherein the predetermined pressure is 9.8 × 10 ⁻⁷ or more.
2. The dip coating method according to claim 1, wherein the pressure is 4.9 × 10 ⁻⁶ Pa. 3. The pressurizing position is: pressurizing position upper limit = (coating speed) × (coating coefficient) × 0.3
3 Pressing position lower limit value = (coating speed) x (coating coefficient) x 0.2
1 ((Coating coefficient) = ｛(radius of inner diameter of coating tank) ² −
3. The dip coating according to claim 1, wherein the value is within a range determined by an upper limit value and a lower limit value determined by (radius of outer diameter of cylindrical substrate) ² ｝ / (radius of outer diameter of cylindrical substrate) ² ). Method. 4. The predetermined pressure is as follows: upper limit of pressurizing force = 6.0 × 10 ⁻⁹ × (radius of outer diameter of cylindrical base) ² lower limit of pressurizing force = 3.0 × 10 ⁻⁹ × ( 4. The dip coating method according to claim 1, wherein the value is within a range determined by an upper limit value and a lower limit value obtained from ( ² ) a radius of an outer diameter of the cylindrical substrate.