JPS63264165A - Film coating equipment - Google Patents

Abstract

PURPOSE:To form a thin film having a uniform thickness even in coating solution low in viscosity by lifting a solution relief part under the parallel surface of a coating jig in an equipment having a mechanism moving a coating jig and a coat forming surface relatively in the vertical direction. CONSTITUTION:In an equipment to prepare a film by spreading coating solution on a vertical coat-forming surface 2 of a body 1 to be coated is arranged a coating jig 3 having a parallel surface facing the coat-forming surface 2 through a space to store coating solution 9. There is provided a mechanism to relatively move the coating jig 3 and the coat-forming surface 2 in the vertical direction and the slit-type solution relief part 16 is arranged under the parallel surface of the coating jig 3. As a result, even when the coating solution is low in viscosity, it is possible to provide a film having a good appearance and a uniform thickness on a vertical coat-forming surface of the body to be coated and simplify the coating process.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a thin film coating device for forming a thin film 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, flag 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, functional materials are dissolved or dispersed in an organic solvent, and in some cases, adhesives, plasticizers, etc. are added to the coating solution, which is then filled into a coating solution tank. This is a simple method in which the object to be coated is immersed in the paint, and then the object to be coated is pulled up and dried to form a coating film.
Moreover, by adjusting the viscosity of the coating liquid and the rate at which the object to be coated is pulled up from the coating liquid, a thin film can be obtained relatively easily. However, this dipping method differs from brushing or spray gun methods; first, an excess of the desired amount of coating liquid is applied onto the coating surface, and then the specified amount of coating liquid is applied by gravity. Since this is a coating method based on excess application (post-metering type) that reduces the amount of liquid to 100%, it requires a coating liquid in an amount greater than the specified amount.

The amount of this extra coating liquid increases in proportion to the coating area, and as the coating area increases, it is necessary to fill a coating liquid tank with a large amount of excess coating liquid and wipe it off. Also, examples of organic solvents include tetrahydrofuran and benzene.

When using a substance with a relatively low boiling point such as toluene, methyl ethyl ketone, 1.2'; Since a uniformly dispersed coating film cannot be obtained with the liquid, sufficient control of the coating liquid is required. 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 to be coated. It is often necessary to apply the product twice by turning it upside down.

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 making the volume of the coating liquid much larger than the volume of the part of the object being immersed. This is not practical, especially when the object to be coated is large.

Furthermore, even if the pulling speed of the object to be coated is slowed to obtain a thin film, if the volume of the part of the object to be coated immersed in the coating liquid is large compared to the amount of the coating liquid, the surface of the coating liquid at the time of pulling up may be As the downward fluctuation increases, the relative speed of the coating film forming surface to the coating liquid level increases, making it impossible to obtain a thin film with the desired thickness. In order to obtain a thin film of the required thickness, it is necessary to further increase the amount of coating liquid or to further slow down the pulling speed. It is undesirable to apply an excessive amount of liquid, and if the pulling speed is slowed down, it will be difficult to maintain a constant speed, and it will take a long time to apply, increasing the risk of being affected by the environment. , variations in film thickness are 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. We would like to propose that a coating device equipped with a coating jig having parallel surfaces facing each other via a coating device and a mechanism for moving the coating film forming surface and the coating jig relative to each other in the vertical direction is effective. (Japanese Patent Application No. 60-174930"). Using such a coating device, the gap between the coating film forming surface and the parallel surface of the coating jig facing the same can be used as the coating liquid reservoir instead of the coating liquid tank in the dipping method. The coating solution is stored in this gap, and the coating film formation surface and the coating jig are moved relative to each other in the vertical direction to form a coating film from top to bottom on the coating film formation surface. By using the reservoir, 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 that the invention seeks to solve]

However, the coating liquid storage section of the above-mentioned device is located at the top.

The lower part is an open gap, and the coating liquid is stored without flowing away from the lower part due to the shear force between the coating film formation surface, the parallel surface of the coating jig, and the coating liquid and the surface tension of the coating liquid. This is to ensure that the coating liquid remains within the body, and the higher the viscosity of the coating liquid, the easier it is to accumulate. On the other hand, in order to reduce the thickness of the coating film, it is preferable that the viscosity of the coating liquid is low;
When the viscosity decreases, the coating liquid tends to flow out from the lower part of the reservoir, causing problems such as dripping and other appearance defects on the coating film.

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

[Means for solving problems]

In order to achieve the above object, the present invention provides a thin film coating device that applies a coating liquid to a vertical coating film forming surface of an object to form a thin film. a coating jig having parallel surfaces facing each other with a spacing therebetween, and a mechanism for moving the coating jig and the coating film forming surface relative to each other in the vertical direction; A liquid escape part is provided in the lower part of the container.

[Effect]

In this way, a liquid escape part is provided at the lower part of the parallel plane that faces the vertical coating film forming surface and forms the coating liquid storage part, so that the liquid escapes downward from the opening at the bottom of the storage part when the coating film is formed. By guiding the coating liquid to be applied to this liquid escape part using capillarity and surface tension, it is possible to prevent the coating liquid from flowing out and to eliminate the occurrence of poor appearance of the coating film due to dripping.

〔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 the surface of a cylindrical substrate, such as a photosensitive drum for electrophotography. A ring-shaped application jig 3 surrounds it. The coating jig 3 is
A ring-shaped polymer member 1, for example, a ring-shaped Teflon member 7, which has a coating film forming surface 2 formed by vertically positioning the outer surface of the base body, and a parallel surface 4 facing each other at a required constant distance A.
, a ring-shaped metal member 9, such as the ring-shaped stainless steel member 6, to which it is attached, and a ring-shaped polymer member 1, such as the ring-shaped Teflon member 15, attached to the lower surface of these members 6.7. The ring inner surface of the member 15 forms the same parallel surface as the parallel surface 4, and the member 15
The surface facing the members 6 and 7 is provided with a ring-shaped minute step reaching the inner surface of the ring, and the step is
．． 7, and the slit opens to the coating film forming surface 4 at the lower end of the parallel surface 4, forming a slit-like liquid escape section 16. . The upper end of the coating jig 3 is a receiving part 8 having a structure that easily receives the coating liquid 9 supplied from the coating liquid supply device 10. The coating liquid 9 supplied to the receiving part 8 has a width A. , height B
The liquid flows into the coating liquid reservoir 5 which is a ring-shaped gap. Although not shown in FIG. 1, this coating device has a mechanism for lifting the substrate l along a concentric axis with the coating jig 3 in the vertical direction shown by the arrow in FIG. 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 order to store the coating liquid 9 in the coating liquid reservoir 5, which is a gap with open upper and lower parts, it is necessary to It is necessary to increase the shearing force between the coating liquid 9 and the gap and to use the surface tension of the coating liquid 9 to prevent the coating liquid 9 from flowing out from the bottom of the gap.The width of the gap must be adjusted depending on the characteristics of the coating liquid. It is necessary to choose the values of A and height B appropriately. In the case of a commonly used coating liquid, it is desirable that the width A of this gap is 0.1 m+a or more and 5 cI or less, and the height B of this gap is 5ff111 or more and 10 cI or less.

The thickness of the coating film is determined by the relative moving speed between the substrate 1 and the coating jig 3 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. If the moving speed is slowed down, it will be difficult to maintain a constant speed, and it will take longer to form the film, so it is not practical to slow it down too much.Moreover, there will be more chances for it to be influenced by the environment, and there is a risk of variations in film thickness. This is not preferable because it increases the size. When the viscosity of the coating liquid is reduced, the coating liquid tends to flow out from the opening below the coating liquid storage section 5. To prevent such spillage, a liquid escape part 1 is provided in the coating jig.
6 will be provided. By using capillarity and surface tension in the liquid escape portion 16 to guide the coating liquid that is about to flow out from the lower part of the gap, it is possible to prevent the coating liquid from flowing out from the opening below the coating liquid reservoir. can.

As a structure of a coating jig having such a liquid escape part, the structure shown in FIGS. 2(a) to 2(a) yields particularly good results.

FIG. 2(a) shows a structure in which, as shown in FIG. 1, a ring-shaped member 15 having a step is attached to the lower surface of the member 6.7, and a slit-like liquid escape portion 16 is formed. This step difference, that is, the slit interval, does not need to be particularly limited, and may be any interval that allows the capillary phenomenon to be utilized, and can be appropriately selected depending on the coating liquid.

2(c), 2(c), and 2(d) do not require the use of the member 15 (see FIG. 2). (C) is a square slit, Figure 2 (C) is a rounded slit,
Figure (d) shows a slit with a threaded structure, and both have a structure in which a parallel surface is secured below the slit.

The number of slits is determined by the number that can be processed into parallel surfaces, and it is sufficient if - or more slits are formed. Further, the width, depth, etc. of the slit do not need to be particularly limited, and can be appropriately selected depending on the coating liquid.

As a member of the coating jig, when the substrate or coating jig is moved to form a coating film, the coating surface of the substrate may be damaged by dents or scratches due to contact between the coating surface of the substrate and the coating jig due to machine vibrations, etc. Therefore, it is desirable to use a flexible, water-repellent polymer material. In terms of water repellency, it is desirable to use a fluorine-containing polymer, such as Teflon, as the polymer.

A metal material coated with a polymer may be used as the member 7.15, in which case the amount of polymer used can be reduced and the coating jig can be made inexpensive. member 6 and member 7
Furthermore, by making the member 15 detachable, the jig can be easily cleaned at the end of coating or after each coating. Moreover, even if the outer diameter of the cylindrical base changes, if members 7 with different thicknesses and members 15 with different ring inner diameters are prepared, the application jig can be changed without changing the entire application jig. Furthermore, there is an advantage that the problem can be handled to some extent by replacing the member 15.

However, it is not always necessary to make the member 7 and the member 15 a polymer, and they may also be made of metal, for example stainless steel. Especially when the width A can be increased, metal can be used without any problem and the parallel surfaces 4 can be made of a polymer. It also has the advantage that the surface can be easily processed to be smooth, and in some cases, the member 6 and member 7 can be integrated to simplify the structure of the coating jig.

Coating solution supply bag! 10 is a storage tank 11 for coating liquid. A supply pipe 12 for supplying the coating liquid to the coating liquid storage section 5. Valve 13 for controlling the supply amount of coating liquid. It is constituted by an airtight lid 14 for preventing changes in the viscosity of the coating liquid 9 stored in the container. Although such a coating liquid supply device 1O is not necessarily required, in the present invention, since the volume of the coating liquid storage section 5 is small and the amount of stored coating liquid is small, the coating liquid is not applied to the coating film forming surface during the coating operation. decrease (coating liquid storage part 5
Since the coating liquid must be frequently replenished, it is desirable to provide such a coating liquid supply device 10. Furthermore, since the upper and lower surfaces of the coating liquid storage section 5 are completely open to the atmosphere, the solvent from the coating liquid there is likely to evaporate and the viscosity of the liquid changes, but the coating liquid in the storage tank 11 maintains a constant viscosity. It is very effective to constantly replenish the coating liquid by the amount consumed. This eliminates changes in the viscosity of the coating liquid at the time of coating. From this point of view, it is preferable that the volume of the receiving part 8 at the upper end of the application jig 3 is as small as possible, and if possible, it is better not to provide it. Further, although FIG. 1 shows one set of the coating liquid supply device 10,
Although the coating device becomes complicated, providing a plurality of sets is more suitable in terms of preventing the above-mentioned change in the viscosity of the coating liquid.

Specific examples will be described below.

Example 1 First, α-type metal-free phthalocyanine is used as a starting material, and between two linear motors placed opposite to each other, α-type metal-free phthalocyanine and a non-magnetic object containing a Teflon piece as a working piece are placed and crushed. L I M M
A C (Linear Induction M
otor Mix-ing and Crashin
g: manufactured by Fuji Electric) was processed for 20 minutes to form a fine powder.

1 part by weight of this finely powdered sample and DMF (N, N-
50 parts by weight of dimethylformamide) solvent was subjected to ultrasonic dispersion treatment. Thereafter, the sample and DMF were separated, filtered, and dried to process metal-free phthalocyanine.

A coating solution was prepared by kneading 50 parts by weight of this metal-free phthalocyanine with 100 parts by weight of a polyester resin (trade name: Vylon 200, manufactured by Toyobo Co., Ltd.) and a tetrahydrofuran (T) IP) solvent.

The above coating liquid was applied to the outer surface of an aluminum cylindrical substrate with an outer diameter of 60mm and a length of 320mm using the coating device shown in Fig. 1, the dimensions of the coating liquid storage part were set to 0.3mm, B was 40+nm, and the cylindrical substrate was coated. When the coating was applied while pulling at a speed of 20 mm/sec, a uniform coating of 0.5 μm±20% over the entire length of 320 mm and a clean appearance without dripping was obtained.

Example 2 Coating was carried out in the same manner as in Example 1, except that the coating jig used in Example 1 was changed to the one shown in FIG. 2(c). The number of slits in the coating jig shown in FIG. 2 (c) was varied in the range of 1 to 4. In all cases, coated films with good appearance were obtained.

Example 3 In addition, on each of the outer surfaces of the cylindrical substrates on which the coating films were formed in Examples 1 and 2, A coating solution is prepared by dissolving 10 parts by weight of pyrazoline (ASPP: manufactured by Anan Kogyo Co., Ltd.) and 10 parts by weight of polymethyl methacrylate resin (PMMA: manufactured by Tokyo Kasei Co., Ltd.) in 15,050 parts by weight of THF (tetrahydrofuran) solvent. Using a coating device, A is 0.5 mm,
When B was set to 30 m and the cylindrical substrate was coated while being pulled up at a speed of 5+ nm/sec, a coating film with a uniform thickness of 15 μm±0.5 μm over the entire length of 320 mm was obtained.

When the product produced in this manner was used as a photoreceptor for electrophotography, it was found to be sufficiently usable for practical use.

Comparative Example 1 When coating was performed according to Example 1 using an aluminum member instead of the Teflon member 7 of the coating jig (Fig. 1) of Example 1, the coating liquid flowed out and the appearance showed dripping. Only defective films were obtained.

Example 4 Pigment (Lionol Blue SM manufactured by Toyo Ink)
10 parts by weight and negative type photopolymer (Tokyo Ohka T)
A coating liquid was prepared by mixing with 50 parts by weight of PRIO resin.

This coating liquid is applied using the coating device shown in Fig. 1 and the coating jig shown in Fig. 2 (a).
) to Fig. 2 (C), the outer diameter is 60 m.
It was coated on the outer surface of an aluminum cylindrical substrate with a length of 60 m. The number of slits in the applicator was varied from 1 to 3. In the coating apparatus shown in FIG. 1, the dimension A of the coating liquid reservoir is set to 0.
3m+a, B is 40mm, and the base is 3InII/
When the coating was applied while being pulled up at a speed of 2 seconds, a coating film having a uniform thickness of 2 μm±20% over the entire axial length was obtained in each case.

Example 5: On the outer surface of the cylindrical substrate on which the coating film was formed in Example 4, 50 parts of tetraethyl silicate, 1 alS, and 10 parts of ethyl acetate were added.
A coating liquid dissolved in 0 parts by weight was applied using the coating apparatus shown in FIG. 1 except that the coating jig was changed from FIG. 2(a) to FIG. 2(d). The threaded part of the application jig has 3 threads. The lengths of the upper and lower parallel surfaces were 5III11. The coating film is 0.
It had a clear appearance of 5 μm±20%.

When a printing plate was prepared using the substrate on which the coating film was formed in this way, a good printing plate could be obtained.

Comparative Example 2 When the coating liquids of Examples 3 and 5 were used in the coating apparatus shown in FIG. 1 with the member 15 removed and the liquid escape part 16 removed, coating of Example 3 resulted in a thick film. Although the liquid could be applied uniformly, in the case of the coating liquid of Example 5, which had a thin film thickness, the coating liquid flowed out and dripped, and a uniform film could not be obtained.

Embodiment 6 FIG. 3 is a sectional view showing another embodiment of the present invention, conceptually showing an example in which the inner wall surface of a cylindrical substrate is used as the coating film forming surface. Components corresponding to those in FIG. 1 are given the same reference numerals.

Using an inner wall coating jig corresponding to the coating jig shown in Fig. 2(a), it is possible to apply a sunlight selective absorption film to a thickness of 0.5 μm on the inner wall of a cylindrical glass tube with an inner diameter of 80 m+. Ta.

Comparative Example 3 Coating was carried out in accordance with Example 6, except that the member 15 was removed from the coating jig of Example 6 and the jig was changed to a jig without the liquid escape part 16. When the film thickness is 1 μm or more, it can be applied uniformly, but when it is less than 1 μm, liquid leakage occurs and a clean coating film 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 the 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-section of the surface on which the coating film is formed has complex irregularities or a curved surface, coating according to the present invention is possible as long as the surface on which the coating film is formed is vertical.

〔Effect of the invention〕

According to the present invention, instead of the coating liquid tank used in the conventional dipping method, the gap between the coating film forming surface of the object to be coated and the parallel surface of the coating jig facing this is used as the coating liquid reservoir. The coating liquid is stored in this gap, and the object to be coated and the coating jig are moved relative to each other in the vertical direction to form a coating film on the coating surface. At this time, the coating liquid tends to flow out from the lower opening of the gap, and tends to flow out particularly when the viscosity of the coating liquid is low. However, by providing a liquid escape part on the parallel surface of the coating jig, it will flow out from the lower part. The coating liquid can be guided to the liquid escape part using capillary phenomenon or the like to prevent the liquid from flowing out.

In addition, the dipping method requires two steps in two directions: immersing the object to be coated in a coating liquid tank and then pulling it up.
The present invention has the advantage of simplifying the coating process because it only requires one step of moving in one direction.

[Brief explanation of the drawing]

FIG. 1 is a conceptual sectional view showing one embodiment of the present invention, and FIGS. 2(a), (c), (C), and (d) are four different embodiments of the coating jig of the present invention. FIG. 3 is a conceptual cross-sectional view showing another embodiment of the present invention. 1. Object to be coated, 2--Coating film forming surface, 3-- Coating jig, 4--Parallel surface, 5--Coating liquid reservoir, 10 Coating liquid 10 and 4 f11 Figure 1 Figure 2 Figure 3

Claims (1)

[Scope of Claims] 1) A thin film coating device that forms a thin film by applying a coating liquid to a vertical coating film forming surface of an object to be coated, in which a coating liquid is stored with respect to the coating film forming surface through an interval. a coating jig having parallel surfaces facing each other, and a mechanism for moving the coating jig and the coating film forming surface relative to each other in the vertical direction; A thin film coating device characterized in that a thin film coating device is provided with a section. 2) A thin film coating device according to claim 1, characterized in that it has a coating liquid supply device. 3) A thin film coating apparatus according to claim 1, wherein the material forming the parallel surface having a liquid escape part of the coating jig facing the coating film forming surface is a polymer.