Drying furnace

Abstract

Provided is a drying furnace capable of detecting the state of a coating film during drying and suppressing variations in the properties of a film obtained by drying the coating film. A drying furnace according to an embodiment of the present invention is provided with a furnace body, a heater, and a sensor. The furnace body allows a carrier sheet supporting the coating film to pass therethrough. The furnace body is provided with a light transmission part. The heater is capable of heating the coating film. The sensor is capable of optically detecting the state of the coating film heated by the heater via the light transmission part from the side opposite to the coating film with respect to the light transmission part.

Description

drying oven

[0001] The present invention relates to a drying oven.

[0002] Conventionally, it has been known to produce film products by drying a coating film. As a drying device for such a coating film, for example, a drying device has been proposed that includes a drying zone for drying a coating film formed by coating on a substrate and generates an air flow parallel to the conveying direction of the coating film (see, for example, Patent Document 1). In recent years, the uses of film products have become more diverse, and precise control of the properties of film products according to the use is desired. However, when a coating film is dried using the drying device described in Patent Document 1, it is difficult to check the state of the coating film during drying, resulting in a problem of variation in the properties of the produced film product.

[0003] Japanese Patent Application Laid-Open No. 2008-302297

[0004] A primary object of the present invention is to provide a drying oven that can detect the state of a coating film during drying and can suppress variations in the properties of the film obtained by drying the coating film.

[0005] [1] A drying oven according to an embodiment of the present invention includes a furnace body, a heater, and a sensor. A carrier sheet supporting a coating film can pass through the furnace body. The furnace body includes a light-transmitting section. The heater is capable of heating the coating film. The sensor is capable of optically detecting the state of the coating film heated by the heater through the light-transmitting section from the opposite side of the light-transmitting section to the coating film. [2] In the drying oven described in [1] above, the heater may be capable of changing its output based on the detection result of the sensor. [3] In the drying oven described in [1] or [2] above, the heater may be an infrared heater capable of emitting infrared rays. The infrared heater may be located on the opposite side of the light-transmitting section to the coating film. [4] The drying oven described in any of [1] to [3] above may further include an airflow generating section. The airflow generating section is configured to generate an airflow in the internal space of the furnace body. [5] In the drying furnace described in [4] above, the airflow generating unit may be capable of changing the direction and / or volume of the airflow based on the detection result of the sensor.

[0006] According to an embodiment of the present invention, it is possible to realize a drying oven that can detect the state of a coating film during drying and can suppress variations in the properties of a film obtained by drying the coating film.

[0007] Fig. 1 is a schematic perspective view of a drying oven according to one embodiment of the present invention. Fig. 2 is a schematic configuration diagram of a heater provided in the drying oven of Fig. 1. Fig. 3 is a cross-sectional view of the heater of Fig. 2 taken along line III-III'.

[0008] Hereinafter, embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited to these embodiments. In addition, in order to clarify the description, the drawings may show the width, thickness, shape, etc. of each part more schematically than in the embodiment, but these are merely examples and do not limit the interpretation of the present invention.

[0009] A. Overview of the Drying Oven FIG. 1 is a schematic diagram of a drying oven according to one embodiment of the present invention. The illustrated drying oven 100 includes a furnace body 1, a heater 2, and a sensor 3. The furnace body 1 typically has a hollow shape. A carrier sheet 6 supporting a coating film 71 can pass through the interior space of the furnace body 1. The furnace body 1 includes a light-transmitting section 12. The heater 2 is capable of heating the coating film 71. The sensor 3 can optically detect the state of the coating film 71 heated by the heater 2 through the light-transmitting section 12 from the opposite side of the coating film 71 relative to the light-transmitting section 12. In other words, the sensor 3 is located outside the furnace body 1. With this configuration, the coating film can be dried by the heater while the sensor located outside the furnace body optically detects the state of the coating film passing through the furnace body. This reduces variation in the properties of the film obtained by drying the coating film.

[0010] In one embodiment, the output of the heater 2 can be changed based on the detection result of the sensor 3. That is, the output of the heater can be adjusted according to the state of the coating film detected by the sensor. Therefore, the drying conditions of the coating film can be appropriately adjusted, and a film having the desired properties can be stably produced.

[0011] In one embodiment, the drying furnace 100 further includes an airflow generating unit 4. The airflow generating unit 4 is configured to generate an airflow in the internal space of the furnace body 1. This allows the coating film passing through the furnace body to dry more smoothly.

[0012] In one embodiment, the airflow generating unit 4 can change the direction and / or volume of the airflow based on the detection result of the sensor 3. That is, the direction and / or volume of the airflow in the furnace body can be adjusted depending on the state of the coating film detected by the sensor. This makes it possible to more appropriately adjust the drying conditions of the coating film, and more stably produce a film having the desired properties.

[0013] In one embodiment, the drying oven 100 further includes a control unit 5. Although not shown, the control unit 5 is electrically connected to the sensor 3 and the heater 2 and / or the airflow generation unit 4. The control unit 5 includes, for example, a central processing unit (CPU), a ROM, and a RAM. The control unit 5 can receive detection results from the sensor 3 and can transmit signals (typically electrical signals) based on the detection results to the heater 2 and / or the airflow generation unit 4. In this embodiment, the heater 2 is configured to change its output in response to the signal transmitted from the control unit 5. The airflow generation unit 4 is also configured to change the direction and / or volume of the airflow in response to the signal transmitted from the control unit 5.

[0014] Examples of the film 72 manufactured by such a drying furnace 100 include perovskite semiconductor films that can be used in photoelectric conversion elements, positive and negative electrodes of lithium ion batteries, various ceramic sensors, and high-performance films.

[0015] The configuration of the drying furnace 100 will be described in detail below.

[0016] B. Carrier Sheet The carrier sheet 6 typically has a long shape. In the illustrated example, the long carrier sheet 6 is movable from the unwinding roll 61 toward the winding roll 62. The carrier sheet 6 passes through the internal space of the furnace body 1 between the unwinding roll 61 and the winding roll 62.

[0017] In the unwinding roll 61, a long carrier sheet 6 is wound in a roll shape around a rotatable unwinding shaft 61a. After being pulled out from the unwinding roll 61, the carrier sheet 6 enters the furnace body 1. Before the carrier sheet 6 enters the furnace body 1, a coating liquid is applied to the carrier sheet 6 to form a coating film 71. The coating film 71 formed on the carrier sheet 6 passes through the internal space of the furnace body 1 as the carrier sheet 6 moves, and is heated and dried by the heater 2. The coating film 71 is then appropriately dried to form a film 72 (dried coating film). The film 72 is discharged from the furnace body 1 while supported by the carrier sheet 6. The carrier sheet 6 supporting the film 72 is wound into a roll shape around a winding shaft 62a, which rotates when a driving force is transmitted thereto, to form the winding roll 62.

[0018] In one embodiment, the drying furnace 100 further includes a coating unit 7. The coating unit 7 is located upstream of the furnace body 1 in the moving direction of the carrier sheet 6. The coating unit 7 is capable of applying a coating liquid onto the carrier sheet 6. The coating unit 7 may have any appropriate configuration.

[0019] The coating liquid contains material components of the film 72 to be produced and a solvent capable of dissolving and / or dispersing the material components. When the film 72 is a perovskite semiconductor film, the coating liquid contains a compound represented by the general formula (ABX ３ ) and a solvent capable of dissolving the compound.

[0020] General formula (ABX ３ Examples of A in the formula (I) include organic amino compounds and alkali metal cations.

[0021] Examples of the organic amino compound include alkylamines such as methylamine, ethylamine, n-butylamine, di-n-butylamine, di-n-hexylamine, trimethylamine, triethylamine, methyl-n-hexylamine, methyldiethylamine, tri-n-hexylamine, and tri-t-butylamine; imidazole; pyrrole; aziridine; carbazole; formamidine; guanidine; aniline; pyridine; 4-t-butylpyridine; phenethylamine; and 5-aminovaleric acid.

[0022] Alkali metal cations are monovalent cations. Examples of alkali metals include cesium, potassium, and rubidium.

[0023] Such A can be used alone or in combination. Among such A, a combination of an organic amino compound and an alkali metal cation is preferred, a combination of an alkylamine, formamidine and an alkali metal is more preferred, and a combination of methylamine (MA), formamidine (FA) and cesium (Cs) is even more preferred.

[0024] General formula (ABX ３ When A in the formula (I) is a combination of an alkylamine (methylamine), formamidine, and an alkali metal (cesium), the molar ratio of the alkylamine to 1 mole of the alkali metal is, for example, 1 to 5, and the molar ratio of the formamidine to 1 mole of the alkali metal is, for example, 14 to 18.

[0025] General formula (ABX ３ ) Examples of B include divalent metal cations, and preferably cations of Group 14 elements (metal elements classified as Group 14 in the periodic table defined by IUPAC in 2019) such as lead and tin.

[0026] Such B can be used alone or in combination. In addition to the divalent metal cations described above, B can also be mixed with a small amount of a trivalent cation such as indium or antimony. Among these B, preferred are cations of Group 14 elements, and more preferred is lead (Pb).

[0027] General formula (ABX ３ In the formula (I), X may be, for example, a halogen atom or an anion source, and preferably a halogen atom. Specific examples of the halogen atom include chlorine, bromine, and iodine.

[0028] Such X can be used alone or in combination. Among these X, a halogen atom is preferable, and a combination of bromine (Br) and iodine (I) is more preferable.

[0029] General formula (ABX ３ ) is particularly preferably Cs ０．０５ FA ０．８０ MA ０．１５ PdI ２．６８ Br ０．３２ and a perovskite compound having a composition of Cs ０．０５ FA ０．８０ MA ０．１５ PdI ２．７５ Br ０．２５ Examples of perovskite compounds include those having the following composition:

[0030] The general formula (ABX ３ Examples of solvents capable of dissolving the compound represented by the formula (I) include organic solvents, and preferred examples include N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), and 2-methoxyethanol. The solvents can be used alone or in combination.

[0031] C. Furnace Body The furnace body 1 typically includes a main body portion 11 and a light-transmitting portion 12. The main body portion 11 is the portion of the furnace body 1 other than the light-transmitting portion 12. The material of the main body portion 11 can be any appropriate heat-resistant material. In one embodiment, the main body portion 11 has a sensor opening 11a. The sensor opening 11a is provided in a portion facing the coating film 71 that passes through the interior of the furnace body 1. The main body portion 11 may have one sensor opening 11a or multiple sensor openings 11a. In the illustrated example, the main body portion 11 has two sensor openings 11a.

[0032] In one embodiment, the light transmitting portion 12 is supported by the main body 11 so as to cover the sensor opening 11 a. As a result, the light transmitting portion 12 faces the coating film 71 passing through the inside of the furnace body 1 with a gap in the thickness direction of the coating film 71.

[0033] The light-transmitting portion 12 is typically capable of transmitting light (electromagnetic waves) with wavelengths of 200 nm to 4000 nm. The total light transmittance of the light-transmitting portion 12 for light with wavelengths of 200 nm to 3500 nm is, for example, 10% to 100%. If the light-transmitting portion 12 is capable of transmitting visible light with wavelengths of 360 nm to 830 nm, the sensor 3 can detect visible changes in the coating film 71 through the light-transmitting portion 12. Furthermore, if the light-transmitting portion 12 is capable of transmitting infrared rays with wavelengths of 1.0 μm to 4.0 μm, as described in detail below, by employing an infrared heater as the heater 2, infrared rays can be irradiated from outside the furnace body 1 through the light-transmitting portion 12 onto the coating film 71 passing through the furnace body 1, thereby drying the coating film 71.

[0034] The light-transmitting portion 12 is preferably made of a material that transmits electromagnetic waves in the infrared region, typically quartz glass. Other possible materials include sapphire and calcium fluoride. The thickness of the light-transmitting portion 12 can be set arbitrarily and appropriately.

[0035] D. Sensor The sensor 3 is located in the external space of the furnace body 1. The sensor 3 is located on the opposite side of the light transmitting section 12 from the coating film 71 that passes through the inside of the furnace body 1. There is no particular limitation on the number of sensors 3. One sensor 3 may be provided for one light transmitting section 12, or multiple sensors 3 may be provided for one light transmitting section 12.

[0036] The sensor 3 may have any appropriate configuration as long as it can optically detect the state of the coating film 71 passing through the interior of the furnace body 1 via the light transmitting portion 12. Examples of the state of the coating film that can be detected by the sensor include the color of the coating film, the surface temperature of the coating film, and the smoothness of the surface of the coating film. In one embodiment, the sensor 3 is capable of detecting the color of the coating film.

[0037] E. Heater The heater 2 may have any appropriate configuration as long as it is capable of heating the coating film 71 passing through the interior of the furnace body 1. Examples of the heater 2 include an electric heater, an infrared heater, and an ultraviolet lamp. The heater 2 may be disposed inside the furnace body 1 or outside the furnace body 1. The number of heaters 2 is not particularly limited and may be, for example, one or more, preferably two or more.

[0038] In the illustrated example, the heater 2 is an infrared heater 2a capable of emitting infrared rays. The infrared heater 2a is arranged on the opposite side of the light-transmitting section 12 from the coating film 71 passing through the interior of the furnace body 1. In other words, the infrared heater 2a is arranged outside the furnace body 1. Therefore, compared to when an infrared heater is arranged inside the furnace body, the influence of heat on the infrared heater can be reduced, and the life of the infrared heater can be extended. Furthermore, the infrared heater 2a can irradiate infrared rays through the light-transmitting section 12 onto the coating film 71 passing through the furnace body 1, thereby drying the coating film 71.

[0039] In one embodiment, the infrared heater 2 a is configured as a wavelength-controlled heater capable of emitting infrared rays with a controlled wavelength. The peak wavelength of the infrared rays emitted by the infrared heater 2 a can be arbitrarily and appropriately adjusted depending on the absorption wavelength of the solvent contained in the coating film. By emitting infrared rays corresponding to the absorption wavelength of the solvent, the infrared heater can smoothly dry the coating film.

[0040] The peak wavelength of the infrared ray is, for example, 0.5 μm to 4.0 μm, preferably 1.0 μm to 3.0 μm, and the spectral half width of the infrared ray is, for example, 3.0 μm or less, preferably 1.0 μm or less.

[0041] As shown in FIG. 2, the infrared heater 2 a configured as a wavelength control heater includes, for example, a filament 23 , a first tube 21 , and a second tube 22 .

[0042] The filament 23 is capable of emitting infrared rays when a voltage is applied to it. In the illustrated example, the filament 23 is disposed in the center of the internal space of the first tube 21.

[0043] The first tube 21 is disposed in the internal space of the second tube 22. The first tube 21 and the second tube 22 are disposed concentrically and share a central axis. The first tube 21 and the second tube 22 function as low-pass filters that absorb infrared rays exceeding the peak wavelength described above. Therefore, the first tube 21 and the second tube 22 selectively transmit infrared rays having the peak wavelength described above among the electromagnetic waves emitted from the filament 23.

[0044] The space between the first tube 21 and the second tube 22 is defined as a flow path 24. A cooling medium such as air or an inert gas can pass through the flow path 24. This prevents heat generated by the filament from being released to the outside of the irradiation unit. As shown in Fig. 3 , the cooling medium flows into the flow path 24 through an inlet 25 provided in the second tube 22, passes through the flow path 24, and is discharged from an outlet 26 provided in the second tube 22.

[0045] In one embodiment, the infrared heater 2a can change its output based on the detection result of the sensor 3. Typically, the infrared heater 2a receives a signal based on the detection result of the sensor 3 from the control unit 5, and varies the voltage applied to the filament 23 in response to the signal. This makes it possible to change the output of the infrared rays emitted.

[0046] 1, the drying oven 100 may include one airflow generation unit 4 or multiple airflow generation units 4. In the illustrated example, the drying oven 100 includes three airflow generation units 4. Hereinafter, the three airflow generation units 4 may be distinguished as a first airflow generation unit 41, a second airflow generation unit 42, and a third airflow generation unit 43.

[0047] In one embodiment, the airflow generating unit 4 includes a first line 44, a second line 45, and a first blower 47. Each of the first line 44 and the second line 45 is typically a pipe through which gas can pass. In the illustrated example, a first end of the first line 44 is located inside the furnace body. The first ends of the first lines 44 included in the first airflow generating unit 41 and the second airflow generating unit 42 are located between the coating film 71 passing through the furnace body 1 and the light transmitting unit 12. The first end of the first line 44 included in the third airflow generating unit 43 is located on the opposite side of the coating film 71 with respect to the carrier sheet 6. The second end of the first line 44 is connected to the first blower 47 outside the furnace body.

[0048] The first ends of the second lines 45 are located within the furnace body. The first ends of the second lines 45 provided in the first airflow generating unit 41 and the second airflow generating unit 42 are located between the coating film 71 passing through the furnace body 1 and the light transmitting unit 12. The first ends of the first lines 44 and the second lines 45 face each other with a gap in the moving direction of the carrier sheet 6. When the first ends of the first lines 44 and the second lines 45 are arranged facing each other with a gap in the moving direction of the carrier sheet 6, the airflow generating unit 4 can generate an airflow along the moving direction of the carrier sheet 6. The first end of the second line 45 provided in the third airflow generating unit 43 is connected to the furnace body 1 so as to communicate with an opening provided in the furnace body 1.

[0049] The first blower 47 is typically capable of discharging a gas (typically air) and may have any suitable configuration.

[0050] Furthermore, the airflow generating unit 4 may further include a second blower 48. When the airflow generating unit includes a second blower, the airflow can be generated more stably inside the furnace body. In the illustrated example, the second airflow generating unit 42 and the third airflow generating unit 43 include the second blower 48. The second end of the second line 45 is connected to the second blower 48. The second blower 48 can be described in the same manner as the first blower 47.

[0051] Furthermore, the airflow generating unit 4 may further include a heating element 46. If the airflow generating unit includes a heating element, the temperature of the airflow generated within the furnace body can be increased. This makes it possible to appropriately adjust the drying environment for the coating film. In the illustrated example, the second airflow generating unit 42 and the third airflow generating unit 43 include a heating element 46. The heating element 46 is provided in the first line 44. The heating element 46 is capable of heating the gas passing through the first line 44. The heating element 46 may have any appropriate configuration.

[0052] Furthermore, the airflow generation unit 4 may further include a blowing unit 49 having a plurality of blowing ports. In the illustrated example, the third airflow generation unit 43 includes the blowing unit 49. A first end of the first line 44 is connected to the blowing unit 49. In the blowing unit 49, the gas supplied from the first line 44 passes through the plurality of blowing ports, and is thereby divided into a plurality of airflows. The blowing unit 49 may have any appropriate configuration.

[0053] In one embodiment, the airflow generating unit 4 can change the direction and / or volume of the airflow based on the detection result of the sensor 3. When changing the volume of the airflow, the airflow generating unit 4 typically receives a signal based on the detection result of the sensor 3 from the control unit 5, and varies the output of the first blower 47 and / or the second blower 48 in response to the signal. This makes it possible to appropriately adjust the volume of the airflow generated inside the furnace body.

[0054] Details of the airflow generating unit 4 capable of changing the direction of the airflow are described in, for example, International Publication No. 2013 / 111647 and Japanese Patent No. 6704764. The entire disclosures of these publications are incorporated herein by reference. When changing the direction of the airflow, the airflow generating unit 4 typically receives a signal from the control unit 5 based on the detection result of the sensor 3, and appropriately adjusts the direction of the airflow generated in the furnace body in response to the signal. More specifically, the first airflow generating unit 41 and the second airflow generating unit 42 generate an airflow in the same direction as the movement direction of the carrier sheet 6 (parallel flow) or an airflow in the opposite direction to the movement direction of the carrier sheet 6 (counterflow) in response to the signal.

[0055] The drying oven according to the embodiment of the present invention can be suitably used to produce films that can be used for various industrial products.

[0056] REFERENCE SIGNS LIST 1 Furnace body 2 Heater 3 Sensor 4 Air flow generating section 6 Carrier sheet 71 Coating film 100 Drying furnace

Claims

1. A drying furnace comprising: a furnace body through which a carrier sheet supporting a coating film can pass, the furnace body having a light-transmitting section; a heater capable of heating the coating film; and a sensor capable of optically detecting the state of the coating film heated by the heater, through the light-transmitting section, from the opposite side of the coating film with respect to the light-transmitting section.

2. The drying furnace according to claim 1, wherein the heater is capable of changing its output based on the detection result of the sensor.

3. A drying furnace as described in claim 1 or 2, wherein the heater is an infrared heater capable of emitting infrared rays and is arranged on the opposite side of the light-transmitting portion to the coating film.

4. The drying furnace according to claim 1 or 2, further comprising an airflow generating unit configured to generate an airflow in the internal space of the furnace body.

5. A drying furnace as described in claim 4, wherein the airflow generating unit is capable of changing the direction and / or volume of the airflow based on the detection results of the sensor.

Images