Cleaning method, cleaning device, and coating device

Abstract

The invention provides a cleaning method, a cleaning device and a coating device, which can well discharge high-viscosity processing liquid from a degassing unit. When cleaning a degassing unit (16) for degassing a processing liquid having a high viscosity, first, a first diluent having a viscosity lower than that of the processing liquid is introduced into the degassing unit (16) (a first liquid introduction step). Then, after the first liquid introduction step, a second diluent having a lower viscosity than the first diluent is introduced into the degassing unit (16) (second liquid introduction step). As a result, it is possible to satisfactorily discharge the processing liquid from the degassing unit (16).

Description

Technical Field

[0001] The present invention relates to a cleaning technology of a degassing unit for degassing a high-viscosity processing liquid. Background Art

[0002] Conventionally, in the manufacturing process of polyimide films for flexible displays, a high-viscosity treatment liquid containing a polyimide precursor (polyamic acid) is applied to a carrier substrate, and a degassing unit is used to remove bubbles and dissolved gases in the treatment liquid.

[0003] A conventional coating device having a degassing unit is described in, for example, Patent Document 1. In the coating device of Patent Document 1, a hollow fiber degassing module is used as the degassing unit.

[0004] Patent Document 1: Japanese Patent Application Publication No. 2020-044465

[0005] In such a coating device, when the treatment liquid is replaced with another type of treatment liquid, when regular maintenance is performed, or when the treatment liquid is retained for a certain period of time, the degassing unit needs to be cleaned. As a method for cleaning the degassing unit, for example, it is conceivable to supply high-pressure air into the degassing unit to discharge most of the treatment liquid from the degassing unit, and then pass a solvent into the degassing unit to rinse away the treatment liquid remaining in the degassing unit.

[0006] However, since the treatment liquid has high viscosity, it is difficult to fully discharge the treatment liquid from the degassing unit in the above-mentioned cleaning method. In particular, when a hollow fiber degassing module is used as a degassing unit, a high-viscosity treatment liquid is retained in a plurality of fine tubular hollow fibers. In this case, it is difficult to evenly supply high-pressure air to a plurality of hollow fibers. Therefore, there is a problem that air and solvent are concentrated in the hollow fiber from which the treatment liquid is discharged first, and the treatment liquid cannot be discharged from other hollow fibers. Summary of the invention

[0007] The present invention has been made in view of such circumstances, and an object of the present invention is to provide a technology capable of properly discharging a high-viscosity processing liquid from a degassing unit.

[0008] To solve the above-mentioned problems, the first invention of the present application is a method for cleaning a degassing unit for degassing a high-viscosity treatment liquid, comprising: a first liquid passing process, in which a first diluent having a viscosity lower than that of the treatment liquid is passed into the degassing unit; and a second liquid passing process, in which, after the first liquid passing process, a second diluent having a viscosity lower than that of the first diluent is passed into the degassing unit.

[0009] The second invention of the present application is a cleaning method according to the first invention, which further includes: a first dilution process, before the first liquid passes into the process, diluting the treatment liquid with a solvent of the treatment liquid to generate the first diluted liquid; and a second dilution process, after the first liquid passes into the process and before the second liquid passes into the process, diluting the first diluted liquid with the solvent to generate the second diluted liquid.

[0010] The third invention of the present application is a cleaning method according to the second invention, wherein, in the first dilution process, the solvent is supplied to the treatment liquid stored in a dilution tank to generate the first dilution liquid, and the dilution tank is arranged in a circulation pipeline including the degassing unit; in the first liquid introduction process, the first dilution liquid is supplied from the dilution tank to the degassing unit; in the second dilution process, the solvent is supplied to the first dilution liquid returned from the degassing unit to the dilution tank to generate the second dilution liquid; in the second liquid introduction process, the second dilution liquid is supplied from the dilution tank to the degassing unit.

[0011] A fourth invention of the present application is the cleaning method according to the third invention, wherein in the first dilution step, the solvent is supplied to the treatment liquid stored in the dilution tank in an amount of 15 wt % or less of the treatment liquid stored in the dilution tank.

[0012] A fifth invention of the present application is the cleaning method according to the fourth invention, wherein in the first dilution step, the solvent is supplied to the treatment liquid stored in the dilution tank in an amount of 5 wt % or more of the treatment liquid stored in the dilution tank.

[0013] The sixth invention of the present application is the cleaning method according to any one of the first to fifth inventions, wherein the degassing unit has a plurality of hollow fibers through which the treatment liquid passes.

[0014] The seventh invention of the present application is a cleaning device for a degassing unit for degassing a high-viscosity treatment liquid, comprising: a circulation pipeline connected to the degassing unit; a dilution tank arranged in the circulation pipeline; a circulation pump between the dilution tank and the degassing unit to generate a liquid flow in the circulation pipeline; a solvent supply unit to supply a solvent of the treatment liquid to the dilution tank; and a control unit to control the circulation pump and the solvent supply unit. The control unit performs the following processes: a first dilution process, supplying the solvent from the solvent supply unit to the dilution tank to generate a first dilution liquid; a first liquid introduction process, after the first dilution process, introducing the first dilution liquid into the degassing unit by driving the circulation pump; a second dilution process, after the first liquid introduction process, supplying the solvent from the solvent supply unit to the dilution tank to generate a second dilution liquid; and a second liquid introduction process, after the second dilution process, introducing the second dilution liquid into the degassing unit by driving the circulation pump.

[0015] An eighth invention of the present application is the cleaning device according to the seventh invention, wherein in the first dilution step, the solvent is supplied to the treatment liquid stored in the dilution tank in an amount of 15 wt % or less of the treatment liquid stored in the dilution tank.

[0016] A ninth invention of the present application is the cleaning device according to the eighth invention, wherein in the first dilution step, the solvent is supplied to the treatment liquid stored in the dilution tank in an amount of 5 wt % or more of the treatment liquid stored in the dilution tank.

[0017] The tenth invention of the present application is the cleaning device according to any one of the seventh to ninth inventions, wherein the degassing unit includes a plurality of hollow fibers through which the treatment liquid passes.

[0018] The eleventh invention of the present application is a coating device for coating a high-viscosity processing liquid onto a substrate, comprising: a coating part for coating the processing liquid onto the substrate; and a liquid supply part for supplying the processing liquid to the coating part, wherein the liquid supply part comprises: the degassing unit; and the cleaning device described in any one of the seventh to tenth inventions.

[0019] According to the first to eleventh inventions of the present application, after the high-viscosity treatment liquid in the degassing unit is replaced with the first diluent having a lower viscosity than the treatment liquid, the high-viscosity treatment liquid in the degassing unit is replaced with the second diluent having a lower viscosity than the first diluent. Thus, the treatment liquid can be discharged well from the degassing unit.

[0020] In particular, according to the second invention of the present application, the degassing unit can be cleaned without mixing substances different from the solute and the solvent of the processing liquid.

[0021] In particular, according to the third invention of the present application, it is possible to circulate the liquid in the circulation line including the degassing unit and the dilution tank, and to repeat the dilution and the introduction of the liquid.

[0022] In particular, according to the fourth invention or the eighth invention of the present application, the processing liquid in the degassing unit can be replaced satisfactorily using the first diluent having a similar viscosity.

[0023] In particular, according to the fifth invention or the ninth invention of the present application, the number of repetitions of dilution and liquid introduction can be suppressed.

[0024] In particular, according to the sixth or tenth invention of the present application, the treatment liquid can be removed satisfactorily from the inside of the hollow fiber where the treatment liquid is likely to remain. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a diagram showing the structure of a coating device.

[0026] Figure 2 It is a perspective view of the coating part.

[0027] Figure 3 It is a control block diagram of the coating device.

[0028] Figure 4 It is a diagram showing the structure of a degassing unit.

[0029] Figure 5 It is a figure which shows the structure of a cleaning device.

[0030] Figure 6 This is a flowchart showing the procedure of the cleaning process of the degassing unit.

[0031] Figure 7 This is a diagram showing the results of cleaning the degassing unit using a cleaning device.

[0032] Description of Reference Numerals

[0033] 1Coating device

[0034] 9 substrates

[0035] 10Liquid supply unit

[0036] 11 Liquid supply tank

[0037] 12Liquid supply piping

[0038] 13 Main pump

[0039] 14 Auxiliary pump

[0040] 15 Filters

[0041] 16 Degassing unit

[0042] 20 coating department

[0043] 30 Control Department

[0044] 41 Cabinet

[0045] 42 Hollow Fiber

[0046] 43 Pressure relief mechanism

[0047] 50Cleaning device

[0048] 51 circulation pipeline

[0049] 52 dilution tank

[0050] 53 circulation pump

[0051] 54Solvent supply unit

[0052] 55 First three-way valve

[0053] 56 Second three-way valve

[0054] 57 Cleaning pipes

[0055] 58 Drainage Department DETAILED DESCRIPTION

[0056] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0057] <1. Regarding the structure of the coating device>

[0058] Figure 1 1 is a diagram showing the structure of a coating device 1 according to an embodiment of the present invention. The coating device 1 is used in a manufacturing process of a polyimide film as a substrate of a flexible display. In the manufacturing process of the polyimide film, first, in the coating device 1, a high-viscosity processing liquid (varnish) is applied to the upper surface of a glass carrier substrate 9 (hereinafter referred to as "substrate 9"). Then, in other devices, the processing liquid applied to the substrate 9 is subjected to treatments such as heating, decompression, and sintering. Thus, a thin-film polyimide film is manufactured.

[0059] like Figure 1 As shown, the coating device 1 of the present embodiment includes a liquid supply unit 10 , a coating unit 20 , and a control unit 30 .

[0060] The liquid supply unit 10 supplies a high-viscosity treatment liquid to the coating unit 20. Figure 1 As shown, the liquid supply unit 10 includes a plurality of liquid supply tanks 11 , a liquid supply pipe 12 , a main pump 13 , an auxiliary pump 14 , a filter 15 , and a degassing unit 16 .

[0061] The liquid supply tank 11 is a container for storing the treatment liquid before supply. The treatment liquid stored in the liquid supply tank 11 contains, for example, a polyimide precursor (polyamic acid) as a solute and NMP (N-methyl-2-pyrrolidone: N-Methyl-2-Pyrrolidone) as a solvent. The concentration of the solute in the treatment liquid is, for example, 15 to 20 wt%. The viscosity of the treatment liquid is, for example, 1000 to 10000 cP (1 to 10 Pa·s). In the following description, the so-called "high viscosity" means a viscosity of 1000 cP (1 Pa·s) or more.

[0062] In addition, Figure 1 In the example of FIG. 1 , the liquid supply unit 10 includes six liquid supply tanks 11. However, the number of liquid supply tanks 11 included in the liquid supply unit 10 may be one to five, or may be seven or more.

[0063] The liquid supply pipe 12 connects the liquid supply tank 11 and the coating unit 20. The upstream end of the liquid supply pipe 12 is connected to the liquid supply tank 11 via the on-off valve 17. The downstream end of the liquid supply pipe 12 is connected to the nozzle 22 of the coating unit 20, which will be described later. In addition, a filter 15, an auxiliary pump 14, a degassing unit 16, and a main pump 13 are provided on the path of the liquid supply pipe 12.

[0064] The main pump 13 is used to deliver the treatment liquid from the liquid supply pipe 12 to the nozzle 22. The main pump 13 is provided in the liquid supply pipe 12 at a position downstream of the degassing unit 16. For example, a tubular vane pump such as a CT (Coaxial Tubephragm) pump or a quantitative ejection PT (Parallel Tubephragm) pump can be used as the main pump 13.

[0065] The auxiliary pump 14 is used to transport the treatment liquid in the liquid supply pipe 12 to the downstream side, similarly to the main pump 13. The auxiliary pump 14 is provided in the liquid supply pipe 12 at a position downstream of the filter 15 and upstream of the degassing unit 16. The auxiliary pump 14 can use a tubular vane pump such as a CT (Coaxial Tubephragm) pump or a quantitative ejection PT (Parallel Tubephragm) pump.

[0066] When the on-off valve 17 is opened and the main pump 13 and the auxiliary pump 14 are operated, a flow of the treatment liquid from the liquid supply tank 11 to the coating unit 20 can be formed in the liquid supply pipe 12. Thus, the treatment liquid is supplied from the liquid supply tank 11 to the coating unit 20. In addition, the liquid supply unit 10 may further include a pressurizing mechanism for supplying gas to the liquid supply tank 11 and pressing out the treatment liquid from the liquid supply tank 11.

[0067] The filter 15 is a unit for filtering the treatment liquid. The filter 15 is provided at a position upstream of the auxiliary pump 14 in the liquid supply pipe 12. The treatment liquid is filtered by the filter 15. Thus, fine dust contained in the treatment liquid is captured and removed by the filter 15. Figure 1 In the example of FIG. 1 , the liquid supply unit 10 has one filter 15, but the liquid supply unit 10 may also have a plurality of filters 15. In this case, the plurality of filters 15 may be connected in parallel to the path of the liquid supply pipe 12. In addition, another filter 15 may be provided at a position downstream of the auxiliary pump 14 in the liquid supply pipe 12.

[0068] The degassing unit 16 is a unit for reducing the amount of dissolved gas in the treatment liquid. The degassing unit 16 is provided in the liquid supply pipe 12 at a position downstream of the auxiliary pump 14 and upstream of the main pump 13. The degassing unit 16 can use a hollow fiber degassing module. The coating device 1 removes bubbles in the treatment liquid or dissolved gas contained in the treatment liquid through the degassing unit 16. Thus, when the treatment liquid applied to the substrate 9 is heated, depressurized, and sintered in the subsequent process, bubbles can be prevented from being generated in the treatment liquid.

[0069] The coating unit 20 is a unit that applies the processing liquid supplied by the liquid supply unit 10 to the substrate 9 . Figure 2 2 is a three-dimensional diagram of the coating unit 20. Figure 1 and Figure 2 As shown, the coating unit 20 includes a stage 21, a nozzle 22, a nozzle holding unit 23, and a moving mechanism 24. In addition, hereinafter, for the sake of convenience, the moving direction of the nozzle 22 in the coating unit 20 is referred to as the "front-rear direction D1", and the horizontal direction orthogonal to the front-rear direction D1 is referred to as the "left-right direction D2".

[0070] The stage 21 is a roughly rectangular holding platform that carries and holds the substrate 9. The stage 21 is formed, for example, of a single piece of stone. The upper surface of the stage 21 is a flat substrate holding surface 211. The substrate holding surface 211 is provided with a plurality of vacuum adsorption holes (not shown in the figure). If the substrate 9 is placed on the substrate holding surface 211, the lower surface of the substrate 9 is adsorbed to the substrate holding surface 211 by the suction force of the vacuum adsorption holes. Thus, the substrate 9 is fixed on the stage 21 in a horizontal position. In addition, a plurality of lifting pins (not shown in the figure) are provided inside the stage 21. When the substrate 9 is moved out of the stage 21, the plurality of lifting pins protrude above the substrate holding surface 211. Thus, the substrate 9 is separated from the substrate holding surface 211.

[0071] The nozzle 22 is disposed above the stage 21. The nozzle 22 has a nozzle body 221 extending in the left-right direction D2. A slit-shaped ejection port 223 extending in the left-right direction D2 is provided at the lower end of the nozzle body 221. The ejection port 223 faces the upper surface of the substrate 9 placed on the stage 21. The processing liquid supplied by the liquid supply unit 10 is stored in the nozzle 22. And the processing liquid is ejected from the ejection port 223 onto the upper surface of the substrate 9.

[0072] The nozzle holding part 23 is a mechanism for holding the nozzle 22 above the substrate holding surface 211. The nozzle holding part 23 includes: a bridge part 231 extending in the left-right direction D2 above the stage 21; and a pair of support parts 232 supporting both ends of the bridge part 231. The nozzle 22 is fixed to the lower surface of the bridge part 231. In addition, the nozzle holding part 23 includes a lifting mechanism 233 for adjusting the height of both ends of the bridge part 231.

[0073] The travel mechanism 24 is used to move the nozzle 22 along the front-to-back direction D1. The travel mechanism 24 has a pair of rails 241 and a pair of linear motors 242. The pair of rails 241 extends along the front-to-back direction D1 near the left and right sides of the stage 21. The pair of rails 241 respectively support a pair of support parts 232 and guide each support part 232 along the front-to-back direction D1. The pair of linear motors 242 move the pair of support parts 232 along the rails 241 along the front-to-back direction D1 through magnetic power. As a result, the nozzle 22 moves along the front-to-back direction D1 together with the nozzle holding part 23.

[0074] When performing the coating process, the coating unit 20 moves the nozzle 22 in the front-rear direction D1 above the substrate 9 and discharges the processing liquid from the discharge port 223. Thus, the processing liquid is applied to the upper surface of the substrate 9.

[0075] The control unit 30 is a means for controlling the operation of each unit in the coating device 1 . Figure 3 1 is a control block diagram of the coating device 1. The control unit 30 is implemented by a computer, for example. Figure 3 As conceptually shown in FIG. 1 , the control unit 30 includes a processor 31 such as a CPU, a memory 32 such as a RAM, and a storage unit 33 such as a hard disk drive. The storage unit 33 stores a computer program P for operating the coating device 1. The computer program P can be read from a computer-readable storage medium such as a CD or a DVD and stored in the storage unit 33. However, the computer program P can also be downloaded to the control unit 30 via a network.

[0076] like Figure 3As shown, the control unit 30 is electrically connected to the above-mentioned on-off valve 17, the main pump 13, the auxiliary pump 14 and the linear motor 242. In addition, the control unit 30 is also electrically connected to the pressure reducing pump 432, the first three-way valve 55, the second three-way valve 56, the blade 521, the circulation pump 53, the on-off valve 543 and the on-off valve 582 described later. The control unit 30 temporarily reads the computer program P and data stored in the storage unit 33 to the memory 32, and the processor 31 performs calculation processing according to the computer program P and the data, thereby controlling the operation of each part in the coating device 1. Thus, the substrate 9 is subjected to coating processing.

[0077] <2. About the degassing unit>

[0078] Next, the degassing unit 16 will be described in more detail. Figure 4 It is a diagram showing the structure of the degassing unit 16 . Figure 4 The degassing unit 16 is a hollow fiber degassing module. Compared with the case of using a degassing tank, the use of a hollow fiber degassing module can realize space saving of the degassing structure.

[0079] like Figure 4 As shown, the degassing unit 16 includes a housing 41 , a plurality of hollow fibers 42 , and a pressure reducing mechanism 43 .

[0080] The housing 41 is a cylindrical frame. The housing 41 has an inlet 411, an outlet 412 and two exhaust ports 413. The inlet 411 is provided at one end of the housing 41. The inlet 411 is fluidically connected to the downstream end of the portion of the liquid supply piping 12 that is closer to the upstream side than the degassing unit 16. The outlet 412 is provided at the other end of the housing 41. The outlet 412 is fluidically connected to the upstream end of the portion of the liquid supply piping 12 that is closer to the downstream side than the degassing unit 16. Two exhaust ports 413 are provided on the side of the housing 41. The exhaust port 413 is connected to the pressure reducing mechanism 43.

[0081] The hollow fiber 42 is a thin and long tubular membrane. The hollow fiber 42 is formed by a gas permeable membrane, and the gas permeable membrane can only pass through the gas in the liquid and the gas. The inner diameter of the hollow fiber 42 is sufficiently smaller than the inner diameter of the liquid supply pipe 12. The inner diameter of the hollow fiber 42 is, for example, 0.5 mm to 3 mm. A plurality of hollow fibers 42 are accommodated in the interior of the housing 41 in a bundled state. The number of hollow fibers 42 accommodated in the housing 41 is, for example, 100 to 1000. However, the inner diameter of the hollow fiber 42 and the number of the hollow fibers 42 can be appropriately changed according to the type and viscosity of the treatment liquid.

[0082] One end of all hollow fibers 42 is connected to a portion of the liquid supply pipe 12 upstream of the degassing unit 16 through the inlet 411. The other end of all hollow fibers 42 is connected to a portion of the liquid supply pipe 12 downstream of the degassing unit 16 through the outlet 412. When a flow of the treatment liquid is formed in the liquid supply pipe 12, the treatment liquid flows from the inlet 411 through the interior of each hollow fiber 42 to the outlet 412.

[0083] The decompression mechanism 43 is used to decompress the internal space of the box body 41. The decompression mechanism 43 includes a decompression pipe 431 and a decompression pump 432. One end of the decompression pipe 431 is connected to the two exhaust ports 413 of the box body 41. The other end of the decompression pipe 431 is connected to the decompression pump 432. When the decompression pump 432 is driven, the gas in the box body 41 is discharged to the outside through the decompression pipe 431. As a result, the air pressure in the box body 41 is reduced.

[0084] Furthermore, when the air pressure in the housing 41 decreases, bubbles contained in the treatment liquid in the hollow fibers 42 and gas dissolved in the treatment liquid in the hollow fibers 42 are discharged to the outside of the hollow fibers 42. Thus, the treatment liquid flowing through the hollow fibers 42 can be degassed.

[0085] <3. Cleaning device for degassing unit>

[0086] In the coating device 1 , the degassing unit 16 needs to be cleaned when the treatment liquid is changed to another type of treatment liquid, during regular maintenance, or when the treatment liquid is retained for a certain period of time.

[0087] Figure 5 is a diagram showing the structure of the cleaning device 50. Figure 5 As shown, the cleaning device 50 includes a circulation line 51, a dilution tank 52, a circulation pump 53, a solvent supply unit 54, and a liquid discharge unit 58. The control unit 30 also functions as a control unit for controlling each unit of the cleaning device 50.

[0088] The circulation line 51 is a ring-shaped pipe. In the present embodiment, a first three-way valve 55 is provided on the liquid supply pipe 12 on the upstream side of the degassing unit 16, and a second three-way valve 56 is provided on the liquid supply pipe 12 on the downstream side of the degassing unit 16. In addition, one end of a cleaning pipe 57 independent of the liquid supply pipe 12 is connected to the first three-way valve 55, and the other end of the cleaning pipe 57 is connected to the second three-way valve 56.

[0089] The first three-way valve 55 has an upstream port 551 connected to the liquid supply pipe 12 on the upstream side, a downstream port 552 connected to the liquid supply pipe 12 on the downstream side, and a cleaning port 553 connected to the cleaning pipe 57. The first three-way valve 55 can be switched between a "first state" and a "second state". In the "first state", the upstream port 551 and the downstream port 552 are open, and the cleaning port 553 is closed; in the "second state", the upstream port 551 is closed, and the downstream port 552 and the cleaning port 553 are open.

[0090] The second three-way valve 56 has an upstream port 561 connected to the liquid supply pipe 12 on the upstream side, a downstream port 562 connected to the liquid supply pipe 12 on the downstream side, and a cleaning port 563 connected to the cleaning pipe 57. The second three-way valve 56 can be switched between a "third state" and a "fourth state". In the "third state", the upstream port 561 and the downstream port 562 are opened, and the cleaning port 563 is closed; in the "fourth state", the downstream port 562 is closed, and the upstream port 561 and the cleaning port 553 are opened.

[0091] In normal use of supplying the treatment liquid to the coating unit 20, the first three-way valve 55 is set to the "first state" and the second three-way valve 56 is set to the "third state". However, when cleaning the degassing unit 16, the first three-way valve 55 is set to the "second state" and the second three-way valve 56 is set to the "fourth state", thereby forming a ring-shaped circulation pipeline 51 including the degassing unit 16 and the cleaning pipe 57.

[0092] The dilution tank 52 is a container for storing a dilution liquid for cleaning the degassing unit 16. The dilution tank 52 is provided in the cleaning pipe 57 of the circulation line 51. The dilution tank 52 has a blade 521 for stirring inside. When the blade 521 rotates, the liquid stored in the dilution tank 52 is stirred.

[0093] The circulation pump 53 is a pump that generates a liquid flow in the circulation line 51. The circulation pump 53 is provided in the cleaning pipe 57 of the circulation line 51. When the first three-way valve 55 is switched to the above-mentioned "second state" and the second three-way valve 56 is switched to the above-mentioned "fourth state", if the circulation pump 53 is operated, a liquid flow is formed in the circulation line 51, which flows from the dilution tank 52 to the degassing unit 16 through the first three-way valve 55 and a liquid flow flows from the degassing unit 16 back to the dilution tank 52 through the second three-way valve 56.

[0094] The solvent supply unit 54 includes a solvent supply source 541 and a solvent supply pipe 542. The solvent supply source 541 stores a solvent for the treatment liquid. The solvent is, for example, NMP (N-methyl-2-pyrrolidone). The end of the solvent supply pipe 542 on the upstream side is connected to the solvent supply source 541. The end of the solvent supply pipe 542 on the downstream side is connected to the dilution tank 52. In addition, an on-off valve 543 is provided on the solvent supply pipe 542. When the on-off valve 543 is opened, the solvent is supplied from the solvent supply source 541 to the dilution tank 52 through the solvent supply pipe 542.

[0095] The drain section 58 includes a drain pipe 581. The drain pipe 581 is connected to the cleaning pipe 57 at a position downstream of the circulation pump 53. The drain pipe 581 is provided with an on-off valve 582. When the on-off valve 582 is opened, the diluent is discharged from the circulation line 51 through the drain pipe 581 to the outside.

[0096] <4. Cleaning of degassing unit>

[0097] Next, a cleaning process of the degassing unit 16 using the above-mentioned cleaning device 50 will be described. Figure 6 This is a flowchart showing the procedure of the cleaning process. Figure 6 The processing is performed by the control unit 30 controlling the operations of the first three-way valve 55, the second three-way valve 56, the vane 521, the circulation pump 53, the on-off valve 543 and the on-off valve 582 according to the computer program P.

[0098] When cleaning the degassing unit 16, first, the treatment liquid is stored in the dilution tank 52 (step S1). Specifically, the first three-way valve 55 is set to the above-mentioned "first state", and the second three-way valve 56 is set to the above-mentioned "fourth state". In addition, the auxiliary pump 14 is operated. Thus, the treatment liquid is supplied to the degassing unit 16, and the treatment liquid discharged from the degassing unit 16 flows into the cleaning pipe 57. Thus, the treatment liquid is stored in the dilution tank 52.

[0099] When the treatment liquid is stored in the dilution tank 52, the first three-way valve 55 is then switched from the "first state" to the "second state". That is, the first three-way valve 55 is set to the "second state", and the second three-way valve 56 is set to the "fourth state". Thus, a loop-shaped circulation line 51 including the degassing unit 16 and the dilution tank 52 is formed (step S2).

[0100] Next, the treatment liquid stored in the dilution tank 52 is diluted with a solvent (step S3: first dilution process). Specifically, by opening the on-off valve 543 of the solvent supply unit 54, the solvent is supplied from the solvent supply source 541 to the dilution tank 52 via the solvent supply pipe 542. When a predetermined amount of solvent is supplied, the on-off valve 543 is closed to stop supplying the solvent. Then, the blade 521 in the dilution tank 52 is rotated to stir the treatment liquid and the solvent. Thus, a first dilution liquid having a lower viscosity than the treatment liquid is generated in the dilution tank 52.

[0101] If the amount of solvent supplied to the treatment liquid is too much, the viscosity of the first dilution liquid is excessively reduced. In this case, it is difficult to replace the treatment liquid in the hollow fiber 42 well in the next step S4. Therefore, in step S3, it is preferred that the amount of solvent supplied from the solvent supply unit 54 to the dilution tank 52 is less than 15wt% of the treatment liquid stored in the dilution tank 52. However, if the amount of solvent supplied to the treatment liquid is too small, excessive repeated dilution is required. Therefore, in step S3, it is preferred that the amount of solvent supplied from the solvent supply unit 54 to the dilution tank 52 is more than 5wt% of the treatment liquid stored in the dilution tank 52.

[0102] In addition, the amount of the first dilution liquid generated in step S3 is preferably equal to or greater than the amount of the treatment liquid in the degassing unit 16 .

[0103] If the generation of the first dilution liquid is completed, the circulation pump 53 is then driven. Thus, the first dilution liquid is supplied from the dilution tank 52 to the degassing unit 16. Then, the first dilution liquid is passed into the plurality of hollow fibers 42 of the degassing unit 16 (step S4: first liquid passing process). Thus, the treatment liquid in the hollow fiber 42 is replaced with the first dilution liquid. The viscosity of the first dilution liquid is not as low as that of a 100% solvent, and its viscosity is slightly lower than that of the treatment liquid. Therefore, the first dilution liquid can be used to press out and replace the treatment liquid in the hollow fiber 42.

[0104] After the first diluent is circulated in the circulation line 51 for a predetermined time, the circulation pump 53 is stopped. Then, the first diluent (strictly speaking, a mixed liquid of the first diluent and the treatment liquid) stored in the dilution tank 52 is diluted with a solvent (step S5: a second dilution process). Specifically, by opening the on-off valve 543 of the solvent supply unit 54, the solvent is supplied from the solvent supply source 541 to the dilution tank 52 via the solvent supply pipe 542. When a predetermined amount of solvent is supplied, the on-off valve 543 is closed to stop supplying the solvent. Then, the blade 521 in the dilution tank 52 is rotated to stir the first dilution and the solvent. As a result, a second dilution having a lower viscosity than the first dilution is generated in the dilution tank 52.

[0105] In step S5, for example, the same amount of solvent as in step S3 is supplied from the solvent supply unit 54 to the dilution tank 52. However, the amount of solvent supplied in step S5 may be different from the amount of solvent supplied in step S3.

[0106] If the generation of the second diluent is completed, the circulation pump 53 is then driven. Thus, the second diluent is supplied from the dilution tank 52 to the degassing unit 16. Then, the second diluent is passed into the plurality of hollow fibers 42 of the degassing unit 16 (step S6: second liquid passing process). Thus, the first diluent in the hollow fiber 42 is replaced with the second diluent. The viscosity of the second diluent is not as low as that of a 100% solvent, and its viscosity is slightly lower than that of the first diluent. Therefore, the first diluent in the hollow fiber 42 can be pressed out and replaced well by the second diluent.

[0107] After the second diluent is circulated in the circulation line 51 for a predetermined time, the circulation pump 53 is stopped. Then, the second diluent (strictly speaking, a mixed liquid of the first diluent and the second diluent) stored in the dilution tank 52 is diluted with a solvent (step S7: a third dilution process). Specifically, by opening the on-off valve 543 of the solvent supply unit 54, the solvent is supplied to the dilution tank 52 from the solvent supply source 541 via the solvent supply pipe 542. When a predetermined amount of solvent is supplied, the on-off valve 543 is closed to stop supplying the solvent. Then, the blade 521 in the dilution tank 52 is rotated to stir the second dilution and the solvent. As a result, a third dilution having a lower viscosity than the second dilution is generated in the dilution tank 52.

[0108] In step S7, the same amount of solvent as in step S3 or step S5 is supplied from the solvent supply unit 54 to the dilution tank 52. However, the amount of solvent supplied in step S7 may be different from the amount of solvent supplied in step S3 or step S5.

[0109] If the generation of the third dilution liquid is completed, the circulation pump 53 is then driven. Thus, the third dilution liquid is supplied from the dilution tank 52 to the degassing unit 16. Then, the third dilution liquid is passed into the plurality of hollow fibers 42 of the degassing unit 16 (step S8: third liquid passing process). Thus, the second dilution liquid in the hollow fiber 42 is replaced by the third dilution liquid. The viscosity of the third dilution liquid is not as low as that of a 100% solvent, and its viscosity is slightly lower than that of the second dilution liquid. Therefore, the third dilution liquid can be well pressed out and replaced in the hollow fiber 42.

[0110] After the third diluent is circulated in the circulation line 51 for a predetermined time, the first three-way valve 55 is switched from the "second state" to the "first state", and the on-off valve 582 of the discharge portion 58 is opened. Thus, the third diluent is discharged from the circulation line 51 to the outside through the discharge pipe 581 (step S9). When the discharge of the third diluent is completed, the circulation pump 53 is stopped, and the on-off valve 582 of the discharge portion 58 is closed again.

[0111] Then, 100% of the solvent is stored in the dilution tank 52 (step S10). Specifically, by opening the on-off valve 543 of the solvent supply unit 54, the solvent is supplied from the solvent supply source 541 to the dilution tank 52 via the solvent supply pipe 542. Thus, the solvent is stored in the dilution tank 52, and the amount of the solvent is equal to or greater than the capacity of the degassing unit 16.

[0112] If the solvent is stored in the dilution tank 52, the first three-way valve 55 is switched from the "first state" to the "second state" again, and the circulation pump 53 is driven. Thus, the solvent is supplied from the dilution tank 52 to the degassing unit 16. Then, the solvent is passed into the plurality of hollow fibers 42 of the degassing unit 16 (step S11: solvent passing process). Thus, the third dilution liquid in the hollow fiber 42 is replaced with the solvent. At this time, the hollow fiber 42 is not filled with the treatment liquid, but with the third dilution liquid having a lower viscosity than the treatment liquid. Therefore, the interior of the hollow fiber 42 can be well replaced by the solvent.

[0113] After the solvent circulates in the circulation line 51 for a predetermined time, the first three-way valve 55 is switched from the "second state" to the "first state" again, and the on-off valve 582 of the drain section 58 is opened. Thus, the solvent is discharged from the circulation line 51 to the outside through the drain pipe 581 (step S12).

[0114] As described above, in the cleaning device 50, after the high-viscosity treatment liquid in the degassing unit 16 is replaced with the first diluent having a lower viscosity than the treatment liquid, it is replaced with the second diluent having a lower viscosity than the first diluent. In this way, the liquid in the degassing unit 16 is repeatedly replaced with the diluent having a slightly lower viscosity. Thus, the liquid in the degassing unit 16 can be replaced well. Therefore, the treatment liquid can be discharged well from the degassing unit 16. In particular, the high-viscosity treatment liquid can be well removed from the inside of the hollow fiber 42 where the treatment liquid is likely to remain.

[0115] In addition, in the cleaning device 50, a circulation line 51 including the degassing unit 16 and the dilution tank 52 is provided, and a dilution liquid for cleaning is generated by supplying a solvent to the treatment liquid in the dilution tank 52. In this way, the liquid can be circulated in the circulation line 51, and dilution and liquid feeding can be repeated. In addition, the degassing unit 16 can be cleaned without mixing a substance different from the solute and solvent of the treatment liquid.

[0116] If the treatment liquid is removed well from the degassing unit 16, when the treatment liquid is changed to another type of treatment liquid, mixing of the treatment liquid before the change and the treatment liquid after the change can be suppressed. In addition, the treatment liquid can be suppressed from solidifying and adhering in the degassing unit 16. In addition, the generation of particles due to the solidification of the treatment liquid can be suppressed.

[0117] <5. Experimental results>

[0118] Figure 7 1 is a diagram showing the results of cleaning the degassing unit 16 using a cleaning device 50 equivalent to the above. Figure 7 In the experiment, after the degassing unit 16 as the hollow fiber degassing module was filled with the treatment liquid, the degassing unit 16 was cleaned in the same order as above. As the treatment liquid, a high-viscosity liquid containing a polyimide precursor (polyamic acid) as a solute and NMP (N-methyl-2-pyrrolidone) as a solvent was used. The amount of the treatment liquid initially stored in the dilution tank 52 was set to 1200 g.

[0119] The amount of solvent supplied to the dilution tank 52 in the primary dilution step is Figure 7 In Example 1, it is 1200 g (100 wt%), in Example 2, it is 240 g (20 wt%), and in Example 3, it is 120 g (10 wt%). In addition, as in the above steps S3 to S8, the dilution process and the liquid introduction process are repeated three times to evaluate the cleaning result of the degassing unit 16. In addition, Figure 7 In the comparative example shown, the above-mentioned diluent was not used, and the degassing unit 16 was cleaned only with a solvent.

[0120] according to Figure 7 The results show that the amount of the treated liquid remaining in the plurality of hollow fibers 42 of the degassing unit 16 in Examples 1 to 3 is reduced compared to the comparative example. It can be seen that by repeatedly replacing the liquid in the degassing unit 16 with a diluent having a slightly lower viscosity, the treated liquid can be discharged from the degassing unit well.

[0121] In particular, compared to Examples 1 and 2, in Example 3, the treatment liquid can be almost completely discharged from the plurality of hollow fibers 42 of the degassing unit 16. It can be seen that when the amount of the solvent supplied in the primary dilution process is set to 10 wt % of the treatment liquid, the cleaning performance is significantly improved. From this result, it can be seen that it is preferable to set the amount of the solvent supplied in the primary dilution process to, for example, 5 wt % or more and 15 wt % or less of the amount of the treatment liquid.

[0122] <6. Modifications>

[0123] As mentioned above, although one embodiment of the present invention has been described, the present invention is not limited to the above embodiment.

[0124] In the above embodiment, the dilution process in the dilution tank 52 is repeated three times. However, the dilution process in the dilution tank 52 may be repeated twice, or may be repeated four times or more.

[0125] In the above-described embodiment, the cleaning device 50 includes the solvent supply unit 54 that automatically supplies the solvent to the dilution tank 52. However, the solvent may be supplied to the dilution tank 52 manually by an operator.

[0126] In addition, in the above embodiment, the direction in which the diluent is introduced into the degassing unit 16 is the same as the direction in which the treatment liquid is usually introduced into the degassing unit 16. However, the direction in which the diluent is introduced into the degassing unit 16 may be opposite to the direction in which the treatment liquid is usually introduced into the degassing unit 16. That is, the direction of circulation in the circulation line 51 may also be opposite to that in the above embodiment.

[0127] In the above embodiment, the diluent or solvent after cleaning is discharged to the drain pipe 581 connected to the circulation line 51. However, the diluent or solvent after cleaning may be discharged to the outside through the liquid supply pipe 12 and the nozzle 22.

[0128] In the above embodiment, the liquid supply unit 10 has one degassing unit 16. However, the liquid supply unit 10 may have a plurality of degassing units 16. In this case, one cleaning device 50 may be provided for the plurality of degassing units 16, or a cleaning device 50 may be provided for each degassing unit 16.

[0129] In the above embodiment, the cleaning device 50 is assembled in the liquid supply part 10 of the coating device 1. However, the cleaning device 50 may be a device independent of the liquid supply part 10 of the coating device 1. In this case, the degassing unit 16 is taken out from the liquid supply part 10, installed in the cleaning device 50, and the cleaning process is performed.

[0130] In addition, although the coating device 1 described above is used in the process of manufacturing the substrate itself of the flexible device, the coating device of the present invention can also be used in the process of forming a protective film on the surface of the substrate after the device is formed. In addition, the coating device of the present invention can also be used in the process of applying an adhesive when bonding substrates to substrates. In addition, the coating device of the present invention can also be used in the manufacturing process of a liquid crystal display device or a semiconductor substrate other than a flexible device. In addition, the coating device of the present invention can also be used in the manufacturing process of batteries such as lithium-ion secondary batteries or fuel cells.

[0131] In the above embodiment, a hollow fiber degassing module is used as the degassing unit 16. However, in the present invention, the degassing unit to be cleaned is not limited to the hollow fiber degassing module. For example, a degassing unit that performs degassing by storing a treatment liquid in a degassing tank and reducing the pressure in the tank may be subjected to the same cleaning treatment as described above.

[0132] In addition, the details of the cleaning device and the coating device may be different from the structures shown in the various figures of the present application. In addition, the various elements mentioned in the above-mentioned embodiment or modified example may be appropriately combined within the range that no contradiction occurs.

Claims

1. A cleaning method for cleaning a degassing unit for degassing a high-viscosity processing liquid, wherein: include: a first liquid introduction step of introducing a first diluent having a viscosity lower than that of the treatment liquid into the degassing unit; as well as A second liquid introducing step, after the first liquid introducing step, introducing a second diluent having a lower viscosity than the first diluent into the degassing unit.

2. The cleaning method according to claim 1, wherein: Also includes: a first dilution step of diluting the treatment liquid with a solvent of the treatment liquid before the first liquid passing step, thereby generating the first diluted liquid; and The second dilution step is to dilute the first diluted liquid with the solvent after the first liquid passing step and before the second liquid passing step, thereby generating the second diluted liquid.

3. The cleaning method according to claim 2, wherein: In the first dilution step, the first dilution liquid is generated by supplying the solvent to the treatment liquid stored in a dilution tank, wherein the dilution tank is provided in a circulation line including the degassing unit. In the first liquid introduction step, the first diluent is supplied from the dilution tank to the degassing unit. In the second dilution step, the second dilution liquid is generated by supplying the solvent to the first dilution liquid returned from the degassing unit to the dilution tank. In the second liquid passing step, the second dilution liquid is supplied from the dilution tank to the degassing unit.

4. The cleaning method according to claim 3, wherein: In the first dilution step, the solvent is supplied to the treatment liquid stored in the dilution tank in an amount of 15 wt % or less of the treatment liquid stored in the dilution tank.

5. The cleaning method according to claim 4, wherein: In the first dilution step, the solvent is supplied to the treatment liquid stored in the dilution tank in an amount of 5 wt % or more of the treatment liquid stored in the dilution tank.

6. The cleaning method according to any one of claims 1 to 5, wherein: The degassing unit has a plurality of hollow fibers through which the treatment liquid is passed.

7. A cleaning device for cleaning a degassing unit for degassing a high-viscosity processing liquid, wherein: have: A circulation pipeline connected to the degassing unit; A dilution tank, arranged in the circulation pipeline; a circulation pump, between the dilution tank and the degassing unit, causing the circulation line to generate a liquid flow; a solvent supply unit that supplies the solvent of the treatment liquid to the dilution tank; and a control unit, controlling the circulation pump and the solvent supply unit, The control unit performs the following steps: a first dilution step of supplying the solvent from the solvent supply unit to the dilution tank to generate a first dilution liquid; a first liquid introduction step, after the first dilution step, introducing the first dilution liquid into the degassing unit by driving the circulation pump; a second dilution step of supplying the solvent from the solvent supply unit to the dilution tank after the first liquid introduction step, thereby generating a second dilution liquid; as well as A second liquid introduction step, after the second dilution step, introducing the second dilution liquid into the degassing unit by driving the circulation pump.

8. The cleaning device according to claim 7, wherein: In the first dilution step, the solvent is supplied to the treatment liquid stored in the dilution tank in an amount of 15 wt % or less of the treatment liquid stored in the dilution tank.

9. The cleaning device according to claim 8, wherein: In the first dilution step, the solvent is supplied to the treatment liquid stored in the dilution tank in an amount of 5 wt % or more of the treatment liquid stored in the dilution tank.

10. The cleaning device according to any one of claims 7 to 9, wherein: The degassing unit has a plurality of hollow fibers through which the treatment liquid is passed.

11. A coating device for coating a high-viscosity processing liquid onto a substrate, wherein: have: a coating unit for coating the processing liquid onto the substrate; and a liquid supply unit for supplying the treatment liquid to the coating unit, The liquid supply part comprises: The degassing unit; and The cleaning device according to any one of claims 7 to 9.

Images