JP7202132B2 - Deaerator and coating device - Google Patents

Description

The present invention relates to a defoaming device for removing gases such as gas dissolved in a liquid and microbubbles, and a coating apparatus equipped with this defoaming device.

Polyimide films are used as substrates for flexible displays. A polyimide film is formed by thinly applying a liquid polyimide material (polyimide varnish) onto a glass substrate using a coating device (slit coater), followed by drying and baking. If many air bubbles are mixed in the polyimide film, the product will be defective, so it is important to prevent the generation of air bubbles during film formation. Conventionally, gases such as dissolved gases and microbubbles contained in the polyimide material are removed before the liquid polyimide material is applied onto the glass substrate. For this purpose, a stirring deaerator is used. Patent Literature 1 discloses a stirring-type defoaming device that agitates a liquid in a tank with a blade to float and remove gas contained in the liquid.

Japanese Patent Application Laid-Open No. 2003-103110

In the case of the stirring type defoaming device disclosed in Patent Document 1, it takes a long time to complete the removal of the gas in the liquid (completion of defoaming). This is particularly noticeable when the liquid to be defoamed is a highly viscous polyimide material (for example, a 3000 cp liquid). For example, it takes about 4 hours to complete the defoaming of 3 to 4 liters of polyimide material. In the case of the applicator used for manufacturing the flexible display as described above, the necessary amount of liquid to be stored in the tank may be, for example, 20 to 40 liters. In order to complete defoaming of such a large amount of liquid before application, it takes too much time with a conventional defoaming apparatus, resulting in poor production efficiency.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to remove gas contained in a liquid in a short period of time.

The present invention comprises a supply channel through which a liquid flows, a fine channel element provided downstream of the supply channel and having a plurality of fine channel holes having a channel area smaller than that of the supply channel, and an enlarged space inside. and a tank for storing the liquid that has passed through the micro-channel hole, and a decompression mechanism for decompressing the expanded space. According to this defoaming device, the expanded space of the tank is depressurized, so that the liquid in the supply channel passes through the fine channel holes and flows into the tank. Since the expanded space is depressurized, the gas contained in the liquid that has passed through the micro-channel holes is foamed, and the liquid is decompressed by the orifice action after passing through the micro-channel holes, promoting foaming. be. Therefore, the gas contained in the liquid is removed in a short time.

Further, preferably, the tank has a guide path for guiding the liquid in a roundabout way from the fine channel element toward the bottom side of the tank. According to this guide path, even if bubbles adhere to the surface of the liquid that has passed through the fine channel element, the bubbles can be easily extinguished while the liquid is flowing along the guide path.

Further, preferably, a liquid reservoir space, which has a channel area larger than that of the supply channel and stores the liquid, is provided on the upstream side of the fine channel element. According to this configuration, the liquid that has flowed through the supply channel once enters the liquid reservoir space. The liquid that has entered the liquid reservoir space flows out from a plurality of fine channel holes that are widely distributed throughout the fine channel element. As a result, the surface area of the liquid exposed to the expanded space inside the tank is increased, further promoting foaming.

The present invention comprises a stage on which a member to be coated is placed, an applicator having a slit for discharging liquid onto the member to be coated, and one of the member to be coated on the stage and the applicator to the other. and a liquid-sending mechanism for supplying the liquid to the applicator, wherein the liquid-sending mechanism has the defoaming device. According to this coating device, the liquid defoamed by the defoaming device is supplied to the applicator, the liquid is discharged from the applicator onto the member to be coated, and a thin film is formed on the member to be coated. The defoaming device prevents the generation of air bubbles during the formation of the thin film. Furthermore, since the gas contained in the liquid is removed in a short time, production efficiency is good.

According to the defoaming device of the present invention, it is possible to remove the gas contained in the liquid in a short period of time.
According to the coating apparatus of the present invention, since the gas contained in the liquid is removed in a short time, production efficiency is good.

It is a schematic block diagram of a coating device. It is a sectional view showing a schematic structure of a defoamer. It is a figure explaining an orifice action. FIG. 11 is a front view showing a modification of the fine channel element; It is a sectional view showing a schematic structure of a deaeration device which has other forms. 1 is a perspective view of a microchannel element; FIG.

[About coating equipment]
FIG. 1 is a schematic configuration diagram of a coating device. The coating device 10 includes a stage 12 on which a substrate (member to be coated) 7 such as glass is placed, an applicator 14 , a driving mechanism 16 and a liquid feeding mechanism 18 . Applicator 14 has slit 20 . A liquid 9 is discharged from the slit 15 onto the substrate 7 on the stage 12 . A drive mechanism 16 moves one of the substrate 7 on the stage 12 and the applicator 14 with respect to the other. The drive mechanism 16 of this embodiment moves the applicator 14 with respect to the stage 12 in a fixed state. For this purpose, the drive mechanism 16 comprises an actuator (not shown) for moving the applicator 14 horizontally. The liquid sending mechanism 18 supplies the liquid 9 to the applicator 14 .

The applicator 14 is long in a direction perpendicular to the direction of movement of the applicator 14 . In the applicator 14, in addition to the slit 20, an enlarged liquid reservoir (manifold) 22 connected to the slit 20 is formed. The slit 15 and the enlarged liquid reservoir 22 are elongated along the longitudinal direction of the applicator 14 . The liquid feeding mechanism 18 has a main tank 24 that stores the liquid 9, a pump 26 that feeds the liquid 9 in the main tank 24, and a pipe 28 that connects the pump 26 and the applicator 14 (enlarged liquid reservoir 22). The liquid-sending mechanism 18 further has a defoaming device 30 for removing gas dissolved in the liquid 9 and gases such as microbubbles. In the form shown in FIG. 1 , the liquid 9 defoamed by the defoamer 30 is supplied to the main tank 24 . The liquid 9 in the main tank 24 is supplied to the applicator 14 by driving the pump 26 . The liquid 9 supplied to the expanded liquid reservoir 22 of the applicator 14 is discharged through the slit 15 . Along with this ejection, the drive mechanism 16 moves the applicator 14 in the horizontal direction. As a result, a thin film of the liquid 9 is formed on the substrate 7 .

[About liquid 9]
The liquid 9 of the present embodiment is a liquid polyimide material (polyimide varnish). The coating device 10 coats the substrate 7 with a polyimide material as the liquid 9 . After application, the liquid 9 is dried and baked to form a polyimide film on the substrate 7 . Polyimide materials are relatively high viscosity liquids. Its viscosity is high, for example 1000 cp or more. The coating device 10 and the defoaming device 30 of the present embodiment are suitable for the high-viscosity liquid 9 of 1000 cp or more (7000 cp or less), and particularly suitable for the liquid 9 of 3000 cp or more. Note that the liquid 9 may be a material other than polyimide, and may be, for example, a varnish containing another resin. Further, the liquid to be defoamed by the defoaming device 30 may be a liquid other than a liquid containing a resin, or may be a liquid used in various fields. Further, the liquid to be defoamed by the defoaming device 30 may be other than the high-viscosity liquid (that is, it may be a liquid of less than 1000 cp).

[Regarding the defoaming device 30]
FIG. 2 is a cross-sectional view showing a schematic configuration of the defoaming device 30. As shown in FIG. The defoaming device 30 includes a supply channel 32 through which the highly viscous liquid 9 flows, a fine channel element 34 provided downstream of the supply channel 32, a tank 38 having an expanded space 40 therein, and a decompression mechanism 42 for decompressing the expanded space 40 (to make it a vacuum pressure). The defoaming device 30 further comprises a container 44 containing the liquid 9 . Hereinafter, the tank 38 is referred to as a "sub-tank 38 (for defoaming)".

The supply channel 32 is configured by piping. One end 33 a side of the supply channel 32 is in the liquid 9 in the container 44 . The other end 33 b side of the supply channel 32 is connected to the wall portion 39 of the sub-tank 38 . An opening/closing valve 46 is provided in the middle of the supply channel 32 . The liquid 9 can flow through the supply channel 32 when the on-off valve 46 is open. The channel diameter (inner diameter) of the supply channel 32 is, for example, 10 mm or more and 19 mm or less. Note that this channel diameter is the minimum value in the supply channel 32 .

In the description of the defoaming device 30, the "upstream side" and the "downstream side" are based on the direction in which the liquid 9 flows. That is, the one end 33a side of the supply channel 32 in the container 44 containing the liquid 9 is the upstream side, and the bottom portion 49 side of the sub-tank 38 from which the liquid 9 is discharged is the downstream side.

The fine channel element 34 of this embodiment is configured by a plate-like member. A plurality (a large number) of micro-channel holes 36 are formed in this plate-like member. The micro-channel hole 36 is formed by a hole penetrating a plate-like member in its thickness direction. Each fine channel hole 36 has a channel area smaller than that of the supply channel 32 . The diameter of the fine channel hole 36 is, for example, 0.1 mm or more and 1.0 mm or less. The liquid 9 can pass through the fine channel holes 36 . Thus, the fine channel element 34 is provided downstream of the supply channel 32 and has a plurality of fine channel holes 36 having a channel area smaller than that of the supply channel 32 . The microchannel element 34 is attached to the wall 39 on the upper side of the sub-tank 38 .

The sub-tank 38 is provided on the downstream side of the fine channel element 34 (opposite side of the supply channel 32). The sub-tank 38 stores the liquid 9 that has passed through the micro-channel holes 36 . The expanded space 40 of the sub-tank 38 is a space expanded from the fine channel hole 36 . The sub-tank 38 becomes a closed container. A decompression mechanism 42 is connected through a first pipe 50 to another wall portion 48 of the sub-tank 38 . A second pipe 52 is connected to a bottom portion (bottom wall portion) 49 of the sub-tank 38 . An on-off valve 54 is provided on the second pipe 52 . When the open/close valve 54 is open, the liquid 9 in the sub-tank 38 can be discharged to the outside. The discharged liquid 9 flows to an external device (main tank 24 in the embodiment of FIG. 1).

A configuration of the wall portion 39 will be described. A hole is provided in a part of the wall of the sub-tank 38, and a plate-like fine channel element 34 is provided so as to block the hole. A lid member 56 is attached so as to cover the fine channel element 34 . A seal member (O-ring) 37 is provided around (edge) of the fine channel element 34 . The supply channel 32 is connected to the cover member 56 . The lid member 56 faces the fine channel element 34 and is provided with a space therebetween, whereby a liquid reservoir space 58 is provided between the lid member 56 and the fine channel element 34 . That is, the liquid reservoir space 58 is provided on the upstream side (immediately upstream side) of the fine channel element 34 . The liquid reservoir space 58 is a space having a channel area larger than that of the supply channel 32 , and can store the liquid 9 that has flowed through the supply channel 32 .

The sub-tank 38 has a guideway 60 inside. The guide path 60 guides the liquid 9 in a roundabout way (detour) from the fine channel element 34 toward the bottom 49 side of the sub-tank 38 . The above-mentioned “detour” means having a longer route than the shortest distance from the fine channel element 34 to the liquid surface of the liquid 9 stored in the sub-tank 38 . The liquid 9 that has passed through the fine channel holes 36 flows downward and reaches the upper portion 62 of the guide path 60 . The liquid 9 that has reached the upper portion 62 flows along the guide path 60 toward the bottom portion 49 side of the sub-tank 38 . The guide path 60 is, for example, a member having a groove along which the liquid 9 flows. It should be noted that the guiding path 60 may have a structure other than having a groove. The guideway 60 shown in FIG. 2 includes a plurality of guide members 64a, 64b. Between one guide member 64a and another guide member 64b, a folded portion 65 is provided in which the direction of flow of the liquid 9 changes. The guide path 60 is provided extending from the upper portion 62 to the liquid 9 (at or near the liquid surface) stored in the sub-tank 38 . The guideway 60 may have a form other than that shown. For example, the guideway 60 may have a helical guide member (not shown). By making it spiral, it is possible to realize a "detour" compactly.

The decompression mechanism 42 includes a vacuum pump. The decompression mechanism 42 sucks the gas in the sub-tank 38 through the first pipe 50 and decompresses the expanded space 40 (makes the expanded space 40 a vacuum pressure). The outside of the sub-tank 38 is at atmospheric pressure, and the inside of the container 44 is also at atmospheric pressure. When the expansion space 40 is decompressed from the atmospheric pressure by the decompression mechanism 42, the differential pressure between the inside and outside of the sub-tank 38 causes the liquid 9 in the container 44 to flow through the supply channel 32 toward the sub-tank 38, and further The liquid 9 passes through the fine channel holes 36 and reaches the enlarged space 40 .

According to the defoaming device 30 having the above configuration, the expanded space 40 of the sub-tank 38 is depressurized, so that the liquid 9 in the supply channel 32 passes through the micro-channel holes 36 and flows into the sub-tank 38 . Since the expanded space 40 is decompressed, gases such as dissolved gas and microbubbles contained in the liquid 9 that has passed through the micro-channel holes 36 are foamed. Furthermore, when the liquid 9 passes through the micro-channel holes 36, the pressure is rapidly depressurized by the orifice action, promoting foaming. FIG. 3 is a diagram for explaining the orifice action. When the liquid 9 passes through the micro-channel holes 36, the pressure of the liquid 9 decreases from Q1 (pa: pascal) to Q2 (pa: pascal) as shown in the upper diagram of FIG. That is, the micro-channel hole 36 functions as an orifice. In the present embodiment, when the liquid 9 is sucked out through the micro-channel holes 36 to the decompressed expanded space 40 (enlarged space 40 under vacuum pressure), the expanded space 40 is under vacuum pressure. , and the synergistic effect of the orifice action causes the pressure of the liquid 9 to drop abruptly. Therefore, the dissolved gas and microbubbles in the liquid 9 become bubbles 8 and precipitate in the expanded space 40 . Thereby, dissolved gas and microbubbles in the liquid 9 are removed from the liquid 9 . The generated air bubbles 8 are crushed in the sub-tank 38. - 特許庁

FIG. 4 is a front view showing a modification of the microchannel element 34. FIG. The fine channel element 34 may be a disk-shaped member having a large number of fine channel holes 36 within a circular range. However, as shown in FIG. It may be an elongated plate member that is long in one direction (rectangular plate member when viewed from the front). More microchannel holes 36 are provided side by side in the one direction than in the direction perpendicular to the one direction (the other direction). And it is provided in the sub-tank 38 with the one direction being the horizontal direction. The micro-channel holes 36 arranged in the lower stage and the micro-channel holes 36 arranged in the upper stage differ in position along the one direction. That is, in the fine channel element 34, the fine channel holes 36 are arranged in a zigzag arrangement. In the case of the form (disc shape) shown in FIG. It is likely to be covered with the liquid 9 that has passed through the fine channel holes 36 in the upper portion. For this reason, bubbles degassed from the liquid 9 that has passed through the micro-channel holes 36 on the lower side are likely to be involved in much of the liquid 9 that has passed through the micro-channel holes 36 on the upper side. In contrast, in the case of the form shown in FIG. 4, the amount of the liquid 9 flowing from the top to the bottom of the fine flow channel element 34 is reduced, so that entrainment of defoamed bubbles is reduced. In other words, it is preferable that more micro-channel holes 36 are arranged and distributed in the horizontal direction than in the vertical direction.

In FIG. 2, defoaming of the liquid 9 stored in the sub-tank 38 has been completed. The liquid 9 is supplied from the bottom 49 of the sub-tank 38 to the external device (the main tank 24 in the form of FIG. 1) through the second pipe 52 . During this supply, the operation of reducing the pressure in the sub-tank 38 by the pressure reducing mechanism 42 is stopped. The expanded space 40 of the sub-tank 38 is opened to the atmosphere (atmospheric pressure), and the liquid 9 in the sub-tank 38 is discharged. 2 may also be used as the main tank 24 (see FIG. 1). good.

[Other forms of defoamer]
FIG. 5 is a cross-sectional view showing a schematic configuration of a defoaming device 30 having another form. Hereinafter, the defoaming device 30 shown in FIG. 5 will be referred to as "second form". As much as possible, the same symbols (reference numbers) are given to the same constituent elements as those of the defoaming device 30 shown in FIG. 2, and overlapping explanations are omitted. In the second embodiment, as shown in FIG. 6, the fine channel element 34 is formed by an annular member, and the fine channel hole 36 is provided in this annular member. The micro-channel holes 36 are arranged in a staggered pattern. In addition, more micro-channel holes 36 are arranged and distributed in the horizontal direction than in the vertical direction.

As shown in FIG. 5 , the fine channel element 34 is sandwiched between an upper member 66 and a lower member 67 and provided above the sub-tank 38 . The upper member 66 and the lower member 67 are disk-shaped members. The supply channel 32 is connected to the sub-tank 38 through the center of the upper member 66 . A region between the upper member 66 and the lower member 67 and on the inner peripheral side of the annular microchannel element 34 serves as the liquid reservoir space 58 . The liquid 9 once stored in the liquid storage space 58 passes through the fine channel holes 36 and flows into the expanded space 40 of the sub-tank 38 . A sealing member (O-ring) 68 is provided between each of the upper member 66 and the lower member 67 and the microchannel element 34 . In a second configuration, the upper portion 62 of the guideway 60 is attached to the lower member 67 . The guide path 60 is configured by a cylindrical member. The guide path 60 has a tapered cylindrical portion 69 in order to guide the liquid 9 in a roundabout way from the fine channel element 34 toward the bottom portion 49 side of the sub-tank 38 .

In each of the embodiments described above, the number of fine channel holes 36 should be increased in order to increase the amount (flow rate) of the liquid 9 that flows into the sub-tank 38 through the fine channel element 34 . According to the second form, many micro-channel holes 36 are provided in a space-saving manner. Furthermore, according to the second embodiment, as with the fine channel element 34 shown in FIG. 4, the amount of the liquid 9 flowing from the top to the bottom of the fine channel element 34 is reduced, so the entrainment of defoamed bubbles is reduced. (that is, the efficiency of defoaming is good).

In the case of the second form, as described above, it is easy to increase the number of fine flow channel holes 36, and a large amount of liquid 9 can be defoamed. Therefore, it is possible to defoam a large amount of the liquid 9 in a short time. Therefore, by increasing (increasing) the storage capacity (capacity) of the liquid 9 of the sub-tank 38, the sub-tank 38 can also serve as the main tank 24 shown in FIG. That is, the main tank 24 can be omitted. In this case, the expanded space 40 of the sub-tank 38 is opened to the atmosphere (atmospheric pressure), and the liquid 9 in the sub-tank 38 is supplied to the applicator 14 (see FIG. 1). In addition, the defoaming device 30 of the second embodiment may be applied to the coating device 10 shown in FIG. It may be configured such that the liquid 9 is sent from the tank 24 to the applicator 14 .

[About the defoaming device 30 of each form]
As described above, the defoaming device 30 of each of the above embodiments includes the supply channel 32, the fine channel element 34, the sub-tank 38, and the decompression mechanism . According to this defoaming device 30 , the expanded space 40 of the sub-tank 38 is decompressed by the decompression mechanism 42 , so that the liquid 9 in the supply channel 32 flows through the micro-channel holes 36 into the sub-tank 38 . Since the expanded space 40 is decompressed, gas such as dissolved gas and microbubbles contained in the liquid 9 that has passed through the micro-channel holes 36 is foamed, and further, the liquid 9 passes through the micro-channel holes 36. After passing through the orifice, the pressure is rapidly depressurized, promoting foaming. Therefore, the gas contained in the liquid 9 in the container 44 is removed in a short time.

Therefore, according to the coating apparatus 10 including the defoaming device 30 of each of the above embodiments, the defoamed liquid 9 is supplied to the applicator 14, the liquid 9 is discharged from the applicator 14 onto the substrate 7, A thin film is formed on the substrate 7 . The defoaming device 30 prevents the generation of air bubbles during the thin film formation. Furthermore, since the gas contained in the liquid 9 is removed in a short time, production efficiency is good. The coating device 10 may include a plurality of defoaming devices 30, and the plurality of defoaming devices 30 are alternately connected to the main tank 24 (or the applicator 14) to discharge the liquid 9. good too. In this case, while defoaming is performed in one defoaming device 30, the defoamed liquid 9 is supplied from the other defoaming device 30 to the main tank 24 (or applicator 14). Then, while defoaming is being performed in the other defoaming device 30, the defoamed liquid 9 is supplied from the one defoaming device 30 to the main tank 24 (or the applicator 14). In this manner, the coating apparatus 10 includes a plurality of defoaming devices 30, and the plurality of defoaming devices 30 may be switched for use.

In the defoaming device 30 of each form (FIGS. 2 and 5), the sub-tank 38 has a guide path 60, and the guide path 60 extends from the micro-channel element 34 to the bottom 49 side of the sub-tank 38. It guides the liquid 9 in a roundabout way (bypassing). According to the guiding path 60 , even if bubbles adhere to the surface of the liquid 9 that has passed through the fine channel element 34 , the bubbles can be extinguished while the liquid 9 flows along the guiding path 60 . Even if bubbles remain, the bubbles remain on the surface layer of the liquid 9 that is stored. Since the liquid 9 is discharged to the outside from the bottom 49 of the sub-tank 38, foam is not supplied to the main tank 24 (shown in FIG. 1) and the applicator 14 which are external devices.

In the defoamer 30 of each of the above-described forms (FIGS. 2 and 5), a liquid reservoir space 58 is provided upstream of the fine channel element 34 . The liquid reservoir space 58 has a channel area larger than that of the supply channel 32 and stores the liquid 9 immediately before the fine channel element 34 . Therefore, the liquid 9 that has flowed through the supply channel 32 once enters the liquid reservoir space 58 . Then, the liquid 9 that has entered the liquid reservoir space 58 can flow out from many fine channel holes 36 that are widely distributed throughout the fine channel element 34 . As a result, the surface area of the liquid 9 exposed to the expanded space 40 in the sub-tank 38 is increased, further promoting bubbling.

〔others〕
The embodiments disclosed this time are illustrative in all respects and are not restrictive. The scope of rights of the present invention is not limited to the above-described embodiments, but includes all modifications within the scope of equivalents to the configurations described in the scope of claims. In the micro-channel element 34 shown in FIGS. 4 and 6, the case where the micro-channel holes 36 are provided in two upper and lower rows has been described, but the number of rows (number of stages) can be changed, and may be three or more. may Also, the shape of the fine channel element 34 may be other than the illustrated shape. The installation position, installation posture, etc. of the fine channel element 34 in the sub-tank 38 may be other than those shown in the drawings.

7: Substrate (member to be coated) 9: Liquid 10: Coating device 12: Stage 14: Coating device 15: Slit 16: Driving mechanism 18: Liquid sending mechanism 30: Defoaming device 32: Supply channel 34: Fine channel element 36: Fine channel hole 38: Sub-tank (tank) 40: Expansion space 42: Decompression mechanism 49: Bottom 58: Liquid reservoir space 60: Guidance

Claims (3)

a supply channel through which liquid flows;
a fine channel element provided downstream of the supply channel and having a plurality of fine channel holes having a smaller channel area than the supply channel;
a tank that has an enlarged space inside and stores the liquid that has passed through the fine channel hole;
a decompression mechanism for decompressing the expanded space;
a guideway provided inside the tank along which the liquid flows;
with
The plurality of fine channel holes are open in the upper part of the surface of the fine channel element that extends in the height direction and in the lower part that is lower than the upper part,
The liquid that has passed through the fine channel holes flows downward along the surface that is open in the fine channel holes and spreads in the height direction. flowing along said guideway to
Deaerator. 2. The defoaming device according to claim 1 , wherein a liquid reservoir space, which has a channel area larger than that of said supply channel and stores said liquid, is provided on the upstream side of said fine channel element. One of a stage on which a member to be coated is placed, an applicator having a slit for discharging liquid to the member to be coated, and the member to be coated on the stage and the applicator is moved with respect to the other. A driving mechanism and a liquid feeding mechanism for supplying the liquid to the applicator,
A coating device, wherein the liquid feeding mechanism includes the defoaming device according to claim 1 .

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