JPH0263571A - Thin film coater - Google Patents

Abstract

PURPOSE:To prevent the downward outflow of a coating liquid and to drastically decrease the volume of the coating liquid by providing an outside wall and bottom member to constitute a coating liquid storage part and a coating jig consisting of a sliding member having elasticity to a perpendicular coated film forming surface and pulling up a base body. CONSTITUTION:The coating jig 3 constituted of the outside wall and bottom members which face the perpendicular coated film forming surface of an object 1 to be coated apart a spacing and constitute the coating liquid storage part 7, the sliding member 5 which consists of an elastic material of a projecting shape slidable with the coated film forming surface 2 is mounted to the coated film forming surface. A coating liquid supplying device 9 is disposed to the upper part of the coating jig 3 and the coating liquid 8 supplied to the coating liquid storage part 7 is held by the above- mentioned sliding member 5 so as not to leak and flow out downward. The coating liquid 8 in the storage part 7 sticks to the coated film forming surface 2 to form the coated film when the coating jig 3 and the coated film forming surface 2 are moved opposite in the perpendicular direction. The coating liquid 8 is simultaneously shielded by the sliding member 5 and the coated film forming surface 2 so that the appearance defect by a liquid sag is obviated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a thin film coating device that forms a homogeneous thin film of uniform thickness on the surface of an object.

[Conventional technology]

In recent years, thin films with a thickness of micron order or less, such as surface protective films of magnetic recording media, photosensitive layers of electrophotographic photoreceptors, flux coating films on printed circuit boards, and resist coating films on IC boards, have been developed. The number of technical fields that require membranes with these functions is increasing.

Such a film is required to have uniform functionality, but since it is a thin film, a slight difference in film thickness will cause large variations in functionality. A thick film is desired. For this reason, conventional coating film formation methods such as brush coating and spray gun coating cannot be applied, and spin cord methods and dipping methods are used, which can obtain a coating film with a more uniform thickness. However, the spin code method requires a high-speed rotation drive system, and coating is difficult or impossible when the surface area of the object to be coated is large or the surface shape is complex. The law has been widely used.

In the dipping method, a functional material is dissolved or subdivided into an organic solvent, an adhesive, a plasticizer, etc. are added in some cases, and the coating liquid is filled into a coating liquid paddle. This is a simple method in which the object to be coated is immersed in the coating material, and then the object to be coated is pulled up and dried to form a coating film.It is also relatively easy to apply by adjusting the viscosity of the coating solution and the rate at which the object to be coated is lifted from the coating solution. A thin film can be obtained. However, this dipping coating method differs from brush coating or spray gun methods; first, an excess of the desired amount of coating liquid is applied onto the coating surface, and then the prescribed amount of coating liquid is applied by gravity. Since this is a coating method based on an application type (post-metering type) that reduces the excess amount to 100%, it requires one or more prescribed coating liquids. This amount of extra coating liquid increases in proportion to the coating area, and as the coating area increases, it is necessary to fill the coating liquid tank with the largest amount of extra coating liquid. In addition, when using an organic solvent with a relatively low boiling point such as tetrahydrofuran, benzene toluene, methyl ethyl ketone dichloromethane, etc., the viscosity of the coating solution changes due to evaporation of the solvent and the thickness of the coating film changes. In the case of a dispersion type coating liquid, a more uniform dispersed coating film cannot be obtained, so the coating liquid must be carefully controlled. Also, due to solvent evaporation during coating, when the object is immersed in the coating solution and then pulled up, the coating becomes thicker toward the bottom of the object.
In order to correct such non-uniformity in film thickness on the upper and lower sides, it is often necessary to turn the support upside down and apply the coating twice.

In the case of the dipping method, the thickness of the coating film obtained depends on the relative speed of the coating surface to the coating liquid surface when the object to be coated is pulled up from the coating liquid, and the slower the speed, the thinner the coating film becomes. Particularly when the amount of coating liquid is not that large compared to the volume of the object to be coated, when comparing objects to be coated with different volumes of parts immersed in the coating liquid, even if these objects are pulled up at the same speed, , the speed of the coating film forming surface relative to the liquid level is naturally not constant, so coating films of the same thickness cannot be obtained. In such cases, in order to obtain a coating film with a uniform thickness, the lifting speed should be controlled according to the volume of the part of the object to be coated that is being lifted, or the rate at which the liquid level decreases due to lifting of the object to be coated should not change. It is necessary to provide a coating liquid replenishment mechanism to compensate for this. It is a simple and effective method to reduce liquid level fluctuations and prevent their effects by adding much more coating liquid than the volume of the part of the object to be immersed, but it is easy to use a larger amount of coating liquid than necessary. This is not practical, especially when the object to be coated is large.

Furthermore, even if the lifting speed of the object to be coated is slowed down in order to obtain a thin film, if the volume of the part of the object to be coated immersed in the coating liquid is larger than the volume of the coating liquid, the level of the coating liquid will drop when the object is pulled up. The fluctuations become too large (the relative speed of the coating film forming surface to the coating liquid level becomes faster, making it impossible to obtain a thin film with the desired thickness. In order to obtain a thin film with the required thickness, the amount of coating liquid must be increased. Or, it is necessary to further slow down the pulling speed.It is not desirable to increase the amount of coating liquid excessively, and slowing down the pulling speed makes it difficult to maintain a constant speed, and it takes a long time to coat. Therefore, there is a greater possibility that the film will be influenced by the environment, and variations in film thickness are more likely to occur.

In order to solve these problems, the present inventors have proposed that if the coating film forming surface of the object to be coated can be placed in a vertical state, the coating solution can be stored at intervals with respect to this vertical coating film forming surface. Place a 1I7ft coating jig with parallel surfaces facing each other,
Moreover, it was proposed that a coating device provided with a mechanism for moving the coating film forming surface and the coating jig relative to each other in the vertical direction would be effective (Japanese Patent Application No. 60174930). Furthermore, a coating device is provided in which 6 itf of a coating jig is provided, which has a planar coating liquid leakage prevention member (nurl) made of an elastic member protruding from the bottom of the coating film forming surface so as to be able to slide on the coating film forming surface. Proposed.

When such a coating device is used, the amount of coating liquid used can be significantly reduced compared to the dipping method, and it is also possible to form a thin film with a more uniform thickness.

[Problem to be solved by the invention]

However, the coating liquid reservoir in the former device described above is a gap with open upper and lower parts, and the coating liquid is distributed between the coating film forming surface,
The shear force between the parallel surfaces of the coating jig and the coating liquid and the surface tension of the coating liquid ensure that the coating liquid remains in the reservoir without flowing away from the bottom, and the higher the viscosity of the coating liquid, the higher the viscosity of the coating liquid. Easy to store. On the other hand, in order to reduce the thickness of the coating film, it is preferable that the viscosity of the coating solution is low; however, when the viscosity decreases, the coating solution tends to flow out from the lower part of the reservoir, resulting in poor appearance such as dripping on the coating film. This caused some inconvenience.

Furthermore, in the case of the latter device mentioned above, the thickness of the planar elastic material that forms the slidable bottom surface and the condition of the hardened surface may cause defects in appearance such as scratches and streaks on the coating surface. was there.

The present invention eliminates the above-mentioned drawbacks and makes it possible to form a thin film with good appearance and uniformity on the vertical coating surface of the object to be coated, even when the viscosity of the coating liquid is low. It is an object of the present invention to provide a thin film coating device that can simplify the coating process.

[Means to solve the problem]

In order to achieve the above object, according to the present invention, in a thin film coating device that applies a coating liquid to a vertical coating film forming surface of an object to be coated to form a thin film, A member constituting the other wall and bottom of the coating liquid storage part that faces each other and has this coating film forming surface as one wall, and the coating film forming surface provided on the surface of the bottom that faces the coating film forming surface, slides. A slide made of a convex elastic material with a smooth sliding part! The coating jig consisting of the J1 member is a thin film coating device having a mechanism for relatively moving the coating jig and the coating film forming surface in the vertical direction.

Polymer is preferably used as the elastic material constituting the sliding member.

[Effect]

By sliding the coating film forming surface onto the sliding member made of an elastic material of the coating jig and pulling it up, the coating liquid in the reservoir adheres to the coating film forming surface and forms a coating film, and the coating liquid slides. The paint film will not flow down due to being blocked by the member and the surface on which the paint film is formed, and the poor appearance of the paint film due to dripping will be eliminated. In addition, since the sliding member is made of an elastic material and the sliding portion in contact with the coating film forming surface has a smooth convex shape, the surface will not be damaged.
It is possible to eliminate appearance defects such as streaks and scratches.

〔Example〕

FIG. 1 shows an embodiment of the present invention, and is a conceptual cross-sectional view of an apparatus for applying a thin film to a cylindrical substrate &[H, such as a photosensitive drum for electrophotography. 1
is surrounded by a ring-shaped application jig 3. Application jig 3
The sliding member 5 is made of an elastic material and has a convex sliding portion that is slidable and in contact with the coating film forming surface 2 formed by vertically positioning the outer surface of the base, and a metal member 2 to which the sliding member 5 is attached. For example, it consists of an outer wall and a bottom part 4 made of stainless steel, and the upper end of the coating jig 3 serves as a coating liquid reservoir 7 that receives a coating liquid 8 supplied from a coating liquid supply device 9. The coating liquid 8 supplied to the storage section 7 is held by a sliding member 5 provided on the inner peripheral side of the coating liquid storage part so as to be able to slide on the surface of the base so as not to flow downward.

Although not shown in Fig. 1, this coating device has a mechanism that pulls up the substrate 1 in the vertical direction shown by the arrow in Fig. 1 along a concentric axis with the coating jig 3, or moves the coating jig 3 in the opposite direction to the arrow. A coating film can be formed on the coating film forming surface 2 of the substrate by providing a mechanism for lowering the coating film in the direction.

The sliding member 5 is made of a rubber or plastic sheet and processed into an OIJ song shape, and is installed to be able to slide in contact with the surface of the base as shown in Fig. 1, and the side opposite to the side that contacts the base is the outer wall/bottom. It is tightly fixed to the bottom of 4,
To store a coating liquid 8 without leaking it downward.

Figure 2 shows the structure of the sliding member, and Figure 2 (a)
In this method, a convex elastic material is closely fixed to a metal member, and when in use, air is sent from the air blowing part 6 to inflate the convex elastic material, and the air is evacuated after use. A method that utilizes elasticity while keeping only the convex elastic material tightly fixed.
FIG. 2(C) shows a structure in which the tip is circular like an OIJ song, and the other parts may have a planar structure.

The convex elastic material is selected from a material that is not easily affected by organic solvents. For example, silicone-based, fluorine-based, chloroprene-based, nitrile-based, or polypropylene-based rubbers, or silicone-based, fluorine-based polyethylene-based, or polypropylene-based resins can be used. In addition, the thickness of the elastic material must have enough strength and elasticity to not damage the base surface when sliding.
It is also necessary that the thickness is strong enough to prevent the coating liquid from leaking.

The thickness of the coating film is determined by the relative moving speed between the substrate 1 and coating jig 3 shown in FIG. 1 and the viscosity of the coating liquid. In order to obtain a thin film, it is necessary to slow down this moving speed or to reduce the viscosity of the coating liquid.

In conventional coating apparatuses, when the viscosity of the coating liquid is lowered in an attempt to form a thin film, the coating liquid leaks. Also,
In the case of the sole method, there is no restriction on the viscosity of the coating liquid, but there is a drawback that the coating film forming surface 2 is often damaged due to the hardness, thickness, and finish condition of the planar sole. By providing a convex sliding member made of an elastic material, the coating film forming surface 2 is not damaged, and even a thin film with a thickness of 1 μm or less can be coated uniformly and with good workability.

Reference numeral 9 in FIG. 1 is a coating liquid supply device, which is configured so that ultrasonic vibrations are applied by a shaft 14 to the coating liquid 8 in the coating liquid storage tank 10, which is sealed by a lid 13, so that ultrasonic waves can be dispersed at all times. This allows the coating solution to remain homogeneous for a long time. During coating, this homogeneous coating liquid 8 is sequentially supplied to the coating liquid storage section 7 of the coating jig 3 by adjusting the valve 12 via the supply pipe 11. Therefore, by using such a coating liquid supply device, a coating film is always formed with a coating liquid that is homogeneous and has a constant viscosity, and a thin film that is more homogeneous and has a uniform thickness can be obtained.

Hereinafter, specific examples will be described.

Example 1 A coating solution was prepared by kneading 50 parts of X-type phthalocyanine with a polyester resin (product: Byron 200: Toyobo I> too heavy parts) and a tetrahydrofuran (THF) solvent for 3 hours in a kneading machine. Diameter 60mm,
The first surface of the aluminum cylindrical substrate with a length of 320 mm was
Using the coating device shown in the figure, the cylindrical substrate was coated while being pulled up at a speed of 20 mm/sec, and a uniform coating film of 0.3 μm 120% over the entire length of 320 mm was obtained, with a clean appearance and no drips or scratches. Obtained.

Example 2 Coating was carried out in the same manner as in Example 1, except that the coating jig in Example I was changed to one having a sliding member as shown in FIG. 2 (5).

A coated film with a beautiful appearance was also obtained using this coating device.

Example 3 1-phenyl-3<p-diethylaminestyryl)-5-(p-diethylaminophenyl)- was added to each outer surface of the cylindrical substrate on which the coating film was formed in Example 1.2.
10 parts by weight of 2-pyrazoline (ΔSPP manufactured by Anan Koyo Co., Ltd.) and polymethyl methacrylate resin (PMMΔ: N0 parts by weight manufactured by Tokyo Kasei Co., Ltd.) were mixed with 15 parts by weight of THF (tetrahydrofuran) solvent.
When the cylindrical substrate was pulled up at a speed of 5 mm/sec and coated with this coating liquid using the coating device shown in Fig. 1, a uniform coating of 18 μm ± 0.5 μm was obtained over the entire length of 320 mm. A thick coating film was obtained.

When the product thus produced was used as a photoreceptor for electrophotography, it was obtained that could be used satisfactorily for practical use.

Comparative Example 1 When the coating jig of Example 1 was replaced by a coating jig with parallel surfaces and coating was performed according to Example 1, the coating liquid leaked out and a film with poor appearance and dripping was produced. I could only get it.

Embodiment 4 FIG. 3 is a sectional view showing another embodiment of the present invention,
An example in which the inner wall surface of a cylindrical substrate is used as a coating film formation surface will be conceptually shown. Components corresponding to those in FIG. 1 are given the same reference numerals.

Using an inner wall coating jig corresponding to the coating jig having a sliding member shown in Fig. 2 fa), apply a large sunlight selective absorption film to a thin film with a thickness of 0.5 μm on the inner wall of a cylindrical glass tube with an inner diameter of 80 mm. was completed.

Comparative Example 2 Coating was carried out in the same manner as in Example 4, except that the coating jig used in Example 4 was changed to a flat rubber-type coating jig. When the film thickness is 1 μm or more, it can be coated uniformly, but when it is less than 1 μm, many small scratches occur and a clean coating cannot be obtained.

In the above embodiments, the shape of the coating film forming surface of the substrate is cylindrical, but the shape is not limited to a cylindrical shape, and the present invention is effective as long as it is a flat or curved surface, as long as it is a vertical surface. That is, it goes without saying that even if the horizontal cross-sectional shape of the coating film formation surface is complicatedly uneven or curved, coating according to the present invention is possible as long as the coating film formation surface is vertical.

〔Effect of the invention〕

According to the coating device of the present invention, the large amount of extra coating liquid required in the conventional dippinching method is no longer required, and the amount of coating liquid used can be significantly reduced. Further, the workability is good because the coating film formation can be completed by just applying the coating liquid once.

Furthermore, when applying the coating liquid, the application jig 1i:
Since the IJr member and the coating surface of the object to be coated come into contact with each other and move relative to each other in the vertical direction, the coating liquid does not flow downward, and there is no restriction on the viscosity of the coating liquid. By freely and appropriately selecting the viscosity and the relative lifting speed of the object to be coated, it is possible to form a coating film of the required thickness uniformly and accurately.The sliding member is made of an elastic material. Since the sliding portion that contacts the coating film forming surface has a smooth convex shape, the coating film forming surface is not damaged during sliding, and a coating film with a good appearance can be formed.

[Brief explanation of the drawing]

FIG. 1 is a conceptual cross-sectional view of an embodiment of the coating device of the present invention, FIG. 2(a), FIG. 2, etc.), and FIG. FIG. 3 is a conceptual sectional view showing different embodiments of the coating apparatus of the present invention. 1 Base, 2 Coating film forming surface, 3 Coating jig, 4 Outer wall/bottom, 5 Sliding member, 7 Coating liquid reservoir, 8 Coating liquid, 9
Coating liquid supply device. Figure 1 Figure 2

Claims (1)

[Claims] 1) In a thin film coating device that applies a coating solution to a vertical coating film forming surface of an object to be coated to form a thin film, the device faces the coating film forming surface at a distance and uses this coating film forming surface as one wall. A member constituting the other wall and bottom of the coating liquid reservoir, and a convex elastic member with a smooth sliding portion that can slide on the coating film forming surface provided on the surface of the bottom portion facing the coating film forming surface. 1. A thin film coating apparatus comprising a coating jig comprising a sliding member made of a material, and a mechanism for relatively moving the coating jig and the coating film forming surface in the vertical direction.