Drying device

Abstract

To provide a drying device capable of reducing energy consumption upon drying a coating film relative to a conventional one.SOLUTION: The drying device constituted of a first drying unit and a second drying unit disposed one after the other, each comprising a housing for a substrate with a coating film formed thereon to pass therethrough and a feeder feeding gas into the housing to heat and dry the coating film inside the housing. The second drying unit is disposed on a position where heating of the coating film is carried out prior to the first drying unit, the first drying unit is provided with a first heating source indirectly heating the coating film by heating the gas until the gas is fed from the feeder to the housing of the first drying unit as a heating source of the coating film, the second drying unit is provided with a second heating source directly heating the coating film present in the housing of the second drying unit as a heating source of the coating film, and the second heating source is configured to irradiate the coating film with a laser beam to heat the coating film.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a drying device that heats and dries a coating film formed on a substrate. [Background technology]

[0002] In lithium-ion batteries, a slurry of electrode material is applied to a sheet-like substrate, such as aluminum foil or copper foil, transported by a roll-to-roll machine to form a coating, and the coating is then dried to form the positive and negative electrodes. When forming the positive electrode, a slurry containing primarily NMP (N-methylpyrrolidone) is applied to the substrate. The coating is then dried by heating the coating to evaporate the solvents contained in the coating. When forming the positive electrode, the NMP solvent evaporates from the coating.

[0003] As an example of a drying device for drying a coating film, Patent Document 1 below discloses one that includes a housing having an internal space through which a substrate passes, a heat source for heating gas, and a nozzle for supplying the gas heated by the heat source into the housing. The drying device creates a high-temperature environment within the housing by supplying the gas heated by the heat source into the housing through the nozzle. By exposing the coating film on the substrate being transported to this high-temperature environment for a certain period of time, the solvent (NMP) contained in the slurry and the like are vaporized, thereby drying the coating film. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-097917 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the drying device has a problem in that it consumes a lot of energy when drying the coating film. That is, in the drying device, in order to prevent the concentration of NMP vaporized from the coating film when the coating film is heated in the housing from exceeding the standard value and becoming a hazardous substance, a large amount of gas is supplied into the housing to dilute the NMP so that the concentration of NMP in the housing does not exceed the standard value. Therefore, in order to maintain the temperature in the housing at a temperature necessary for drying the coating film, it was necessary to heat the large amount of gas supplied to the housing to dilute the NMP using a heat source, which resulted in a large amount of energy consumption.

[0006] The present invention has been made in consideration of the above problems, and aims to provide a drying device that can reduce the amount of energy consumed when drying a coating film compared to conventional devices. [Means for solving the problem]

[0007] The drying device of the present invention, which solves the above problems, has a housing section through which a substrate on which a coating film has been formed passes, and a supply section that supplies gas into the housing section, and is a drying device in which a first drying unit and a second drying unit are arranged side by side, each drying the coating film by heating it within the housing section, the second drying unit being positioned at a position where the coating film is heated before the first drying unit, the first drying unit being provided with a first heating source as a heating source for the coating film, which indirectly heats the coating film by heating the gas before it is supplied from the supply section to the housing section of the first drying unit, and the second drying unit being provided with a second heating source as a heating source for the coating film, which directly heats the coating film within the housing section of the second drying unit, and the second heating source is characterized in that it heats the coating film by irradiating it with a laser.

[0008] According to the drying device described above, the second drying unit, which directly heats the coating film by irradiating it with a laser from the second heating source, heats the coating film before the first drying unit, which indirectly heats the coating film via gas from the first heating source. Therefore, after the temperature of the coating film is rapidly increased by the second drying unit, the first drying unit can heat the coating film without causing temperature unevenness in the coating film. This shortens the time required to dry the coating film, thereby reducing the energy consumed in drying the coating film and preventing uneven drying in the coating film. Furthermore, because the coating film is heated by irradiating it with a laser from the second heating source, the entire coating film can be heated uniformly.

[0009] The second heat source may be configured to irradiate the laser over the entire width of the substrate.

[0010] According to this configuration, the second heat source irradiates the laser over the entire width of the substrate, so that the entire coating film can be heated uniformly.

[0011] The laser emitted by the second heat source may be an infrared laser.

[0012] This configuration allows the coating film to be heated from both the surface and the interior, so the temperature of the coating film can be increased rapidly, thereby shortening the time required to dry the coating film and further reducing the energy consumed when drying the coating film.

[0013] The second heating source may also have a first heating section that applies thermal energy to the coating film and a second heating section, and the second heating section may be configured to apply a smaller output of thermal energy to the coating film than the first heating section, and to apply thermal energy to the coating film after the first heating section.

[0014] According to this configuration, the coating film is first heated by the first heating section, and then heated by the second heating section, which is adjusted to apply a smaller amount of thermal energy to the coating film than the first heating section. This allows the temperature of the coating film to be rapidly increased while reducing the temperature difference between the surface and the interior of the coating film. This reduces the time required to dry the coating film while suppressing uneven drying of the coating film. Furthermore, because the coating film is heated by multiple heating sections, i.e., the first heating section and the second heating section, heat can penetrate more deeply into the coating film than when the coating film is heated by a single heating section, improving the heat retention of the coating film after heating.

[0015] In addition, the second heating section may be configured to apply heat energy to the coating film over a wider range than the first heating section in the drying process direction in which heat energy is applied to the coating film in the order from the first heating section to the second heating section.

[0016] According to this configuration, the second heating section can increase the time for heat to penetrate into the coating film, thereby further improving the heat retention of the coating film after heating.

[0017] Furthermore, a configuration may be adopted in which a plurality of the second heating sections are provided and are aligned along the drying processing direction.

[0018] According to this configuration, the second heating section can increase the time for heat to penetrate into the coating film, thereby further improving the heat retention of the coating film after heating.

[0019] In addition, the first drying unit may be provided with an exhaust section for exhausting gas from within the housing section, and a heat exchange section may be provided between the first drying unit and the second drying unit for performing heat exchange between the gas exhausted from within the housing section of the first drying unit by the exhaust section and the gas supplied to the housing section of the second drying unit by the supply section.

[0020] According to this configuration, the heat exchanger exchanges heat between the gas discharged from the housing of the first drying unit by the discharge unit and the gas supplied to the housing of the second drying unit by the supply unit, thereby preventing the solvent vaporized from the coating film from being cooled and liquefied within the housing of the second drying unit. That is, the gas heated by the first heating source and used to heat the coating film within the housing of the first drying unit can heat the gas supplied to the housing of the second drying unit by the supply unit. Therefore, it is possible to maintain the temperature within the housing of the second drying unit at a temperature higher than room temperature without providing a first heating source in the second drying unit. This reduces the energy consumed when drying the coating film and prevents the solvent vaporized from the coating film from being cooled and liquefied within the housing of the second drying unit.

[0021] In addition, the first drying unit may be provided with an exhaust section that exhausts gas from within the housing section, and the supply section may be configured to supply the gas exhausted from within the housing section of the first drying unit by the exhaust section into the housing section of the second drying unit.

[0022] According to this configuration, the gas discharged from the housing of the first drying unit by the exhaust unit is supplied into the housing of the second drying unit by the supply unit, thereby preventing the solvent vaporized from the coating film from being cooled and liquefied in the housing of the second drying unit. In other words, the high-temperature gas heated by the first heating source and used to heat the coating film in the housing of the first drying unit is supplied into the housing of the second drying unit by the supply unit. Therefore, it is possible to maintain the temperature inside the housing of the second drying unit at a temperature higher than room temperature without providing a first heating source in the second drying unit. This reduces the energy consumed when drying the coating film and prevents the solvent vaporized from the coating film from being cooled and liquefied in the housing of the second drying unit.

[0023] The pressure inside the housing of the first drying unit may be set to be lower than the pressure inside the housing of the second drying unit.

[0024] With this configuration, the gas heated in the housing portion of the second drying unit can be supplied into the housing portion of the first drying unit, and the supplied gas can be used as part of the hot air to heat the coating film in the first drying unit.

[0025] Alternatively, a coating film may be formed on both sides of the substrate, and the second heating source may be provided so as to be able to heat each of the coating films formed on both sides of the substrate.

[0026] According to this configuration, even when coating films are formed on both sides of the substrate, the coating films formed on both sides of the substrate can be heated by the second drying unit. [Effects of the Invention]

[0027] According to the drying device of the present invention, the amount of energy consumed when drying a coating film can be reduced compared to conventional methods. [Brief explanation of the drawings]

[0028] [Figure 1] 1 is a diagram schematically illustrating a drying device according to an embodiment of the present invention. [Figure 2] 1A and 1B are diagrams for explaining a second drying unit provided in a drying device according to one embodiment of the present invention, where (a) shows a top view of the second heating source, and (b) shows a side view of the second heating source. [Figure 3] FIG. 2 is a diagram showing the relationship between the temperature of a coating film and the content of a solvent contained in the coating film in one embodiment of the present invention. [Figure 4] 2 is an enlarged view of FIG. 2, illustrating a second drying unit included in the drying device according to one embodiment of the present invention. FIG. [Figure 5]FIG. 10 is a diagram showing one variation of a drying device in one embodiment of the present invention. [Figure 6] FIG. 10 is a diagram showing one variation of a drying device in one embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0029] A drying device according to a first embodiment of the present invention will be described with reference to the drawings. In the following description, the three axes of a Cartesian coordinate system are designated as X, Y, and Z, the horizontal direction is referred to as the X-axis direction and the Y-axis direction, and the direction perpendicular to the XY plane (i.e., the vertical direction) is referred to as the Z-axis direction.

[0030] FIG. 1 is a diagram schematically illustrating a drying device 100 according to the present embodiment.

[0031] The drying apparatus 100 of the present invention is intended to dry a coating film 11 (see Figures 2(a) and 2(b)) formed on a substrate 1 by an application device not shown, and as shown in Figure 1, it is equipped with a first drying unit 2 that dries the coating film by heating it, and a second drying unit 3.

[0032] The coating device in this embodiment is for forming a coating film 11 on a substrate 1, and includes a conveying section (not shown) that conveys the strip-shaped substrate 1, and a coating section (not shown) that applies a slurry of an electrode material (hereinafter referred to as a coating liquid) to the conveyed substrate 1 to form the coating film 11. The coating device applies the coating liquid to the substrate 1 conveyed by the conveying section to form the coating film 11, and the drying device 100 heats and dries the coating film 11 formed on the substrate 1, thereby forming a positive electrode of a lithium-ion battery.

[0033] A metal foil such as an aluminum foil that will become a battery electrode plate for a lithium ion battery is used as the substrate 1. The substrate 1 is a strip-shaped sheet that is long in one direction, and is transported by a transport unit.

[0034] The coating liquid is, for example, a slurry in which an active material, a binder, and a conductive additive are mixed in a solvent such as NMP (N-methyl-pyrrolidone), and is used as a material for battery plates (so-called electrode material) for lithium-ion batteries. By applying this coating liquid onto the substrate 1 using an applicator, a coating film 11 is formed on the substrate 1.

[0035] The first drying unit 2 will be described below.

[0036] The first drying unit 2 is for heating and drying the coating film 11 formed on the substrate 1. In this embodiment, as shown in Fig. 1, three first drying units 2 having the same structure are provided, and the first drying unit 2a, the first drying unit 2b, and the first drying unit 2c are arranged in this order from the upstream side along the conveyance path of the substrate 1. In the following description, when there is no need to distinguish between the first drying unit 2a, the first drying unit 2b, and the first drying unit 2c, they will simply be referred to as the first drying unit 2.

[0037] 1, the first drying unit 2 includes a housing 21 having a space therein through which the substrate 1 passes, a first heating source 22 for heating gas supplied into the housing 21, a nozzle (not shown) for introducing the gas heated by the first heating source 22 into the housing 21, and a first exhaust unit 23 for exhausting the gas from the housing 21. The gas referred to here is air. The gas may be an inert gas such as N2 gas, He gas, or Ar gas.

[0038] As shown in FIG. 1 , the housing 21 is a box-shaped body elongated in the conveyance direction of the substrate 1, and is provided on the conveyance path of the substrate 1 by the conveyance unit. This housing 21 has a space inside through which the substrate 1 passes, and an entrance and exit for the substrate 1 to enter and exit this space. This allows the substrate 1 conveyed by the conveyance unit to pass through the housing 21. The first drying unit 2a, the first drying unit 2b, and the first drying unit 2c are arranged so that each housing 21 is in communication with the conveyance path of the substrate 1. This allows the substrate 1 conveyed by the conveyance unit to pass through the housing 21 of each first drying unit 2 consecutively.

[0039] The first heating source 22 is for indirectly heating the coating film 11 by heating the gas supplied into the housing part 21. This first heating source 22 is a heater such as an electric heater or a heat medium heater, and is configured to heat the gas before it is introduced into the housing part 21 by the nozzle until it reaches a predetermined temperature (a temperature necessary to dry the coating film 11).

[0040] The gas heated by the first heating source 22 is then introduced into the housing 21 from a nozzle through the circulation path 51 (see FIG. 1). This creates a high-temperature environment inside the housing 21. As the substrate 1 transported by the transport unit passes through the housing 21, the coating film 11 on the substrate 1 is exposed to the high-temperature environment and heated, causing the solvent to evaporate from the coating film 11. In other words, the first heating source 22 heats the coating film 11 from the surface by applying thermal energy to the coating film 11 via the gas.

[0041] The first exhaust portion 23 is an opening for exhausting gas inside the housing portion 21 to the outside of the housing portion 11, and is formed in the wall portion of the housing portion 21. Then, gas containing the solvent vaporized from the coating film 11 is exhausted to the outside of the housing portion 21 from the first exhaust portion 23.

[0042] In addition, the first drying unit 2 is provided with a solvent recovery unit 4 that performs a solvent recovery process on the gas discharged from the first discharge section 23, as shown in Figure 1, and a circulation path 5 that circulates the gas between the housing section 21 and the solvent recovery unit 4.

[0043] The solvent recovery unit 4 is provided to liquefy and recover the solvent vaporized from the coating film 11 within the housing 21, and is attached to the housing 21. As shown in Fig. 1, the solvent recovery unit 4 in this embodiment has a cooling section 41 that cools the gas containing the solvent vaporized from the coating film 11, a recovery section 42 that stores the solvent liquefied by being cooled by the cooling section 41, and a recovery path 43 that connects the cooling section 41 and the recovery section 42.

[0044] The cooling unit 41 is for cooling a gas containing a solvent to liquefy the solvent. The cooling unit 41 is a cooler that uses a water-cooling system and has a main body 44 having a cavity through which gas flows, and a refrigerant flow path (not shown) through which water flows as a refrigerant.

[0045] The main body 44 is a housing having a cavity inside through which gas flows, and is connected to the housing 21 by the circulation path 5. As a result, gas containing the solvent vaporized from the coating film inside the housing 21 flows into the main body 44 via the circulation path 5.

[0046] The refrigerant flow path is a flow path through which the refrigerant flows, and is provided inside the main body 44. By flowing the refrigerant through this refrigerant flow path, the gas inside the main body 44 that has flowed from the housing 21 via the circulation path 5 is cooled. As a result, the solvent contained in the gas is liquefied.

[0047] The recovery section 42 recovers the solvent liquefied in the cooling section 41, and is connected to the cooling section 41 by a recovery path 43. A pump (not shown) is provided in the recovery path 43, and the solvent liquefied in the cooling section 41 is sent to the recovery section 42 via the recovery path 43 by this pump. In this way, the solvent is recovered in the recovery section 42. The gas from which the solvent has been recovered is discharged from the main body 44 of the cooling section 41 to the circulation path 5 as a low-concentration gas in which the concentration of the solvent contained therein has been reduced.

[0048] The circulation path 5 is for circulating gas between the first drying unit 2 and the solvent recovery unit 4. As shown in FIG. 1 , the circulation path 5 in this embodiment is composed of a circulation path 51 connected to send gas from the first heating source 22 to the housing 21, a circulation path 52 connected to send gas from the housing 21 to the cooling unit 41, and a circulation path 53 connected to send gas from the cooling unit 41 to the first heating source 22. Fans for circulating gas are provided at various locations in the circulation path 5. These fans circulate the gas via the circulation path 5 from the first heating source 22 to the housing 21, the cooling unit 41, and the first heating source 22.

[0049] The first drying unit 2 is also provided with a supply section 61 that supplies the gas circulated by the circulation path 5. The supply section 61 is a supply source for supplying the first drying unit 2 with a gas (hereinafter referred to as low-concentration gas) containing a solvent at a concentration lower than the concentration of the solvent contained in the gas after the solvent has been recovered by the solvent recovery unit 4.

[0050] 1, this supply unit 61 is connected to the circulation path 53 by a supply path 62 so that the supplied low-concentration gas can merge with the gas from which the solvent has been recovered by the solvent recovery unit 4, on the front side of the first heating source 22. A fan (not shown) is provided in the supply path 62, and the low-concentration gas is supplied from the supply unit 61 to the circulation path 5 via the supply path 62 by this fan. This makes it possible to reduce the concentration of the solvent contained in the gas circulated by the circulation path 5.

[0051] Furthermore, the supply unit 61 continues to supply an amount of gas capable of sufficiently diluting the solvent during operation of the drying device 100 to prevent the concentration of the solvent contained in the gas from exceeding a reference value and becoming a hazardous substance in each of the first drying unit 2, the solvent recovery unit 4, and the circulation path 5. The reference value is the limit value at which the solvent explodes.

[0052] The gas from which the solvent has been recovered by the solvent recovery unit 4 and the low-concentration gas supplied by the supply unit 61 are combined and circulated through the circulation path 5. The resulting gas is heated by the first heating source 22 and introduced into the housing 21 through a nozzle. That is, the gas for diluting the solvent is heated by the first heating source 22 and supplied into the housing 21 as the gas for heating the coating film 11. This makes it possible to heat the coating film 11 within the housing 21 while preventing the solvent from becoming a hazardous substance within the housing 21.

[0053] The first drying unit 2 is also provided with an exhaust section 71 for exhausting a portion of the gas circulated through the circulation path 5 to the outside of the apparatus. As shown in FIG. 1 , the exhaust section 71 is connected to an exhaust path 72 on the side of the circulation path 53, which sends gas from the cooling section 41 to the first heating source 22, before the position where the low-concentration gas is supplied by the supply section 61. The exhaust path 72 is provided with a fan (not shown), and the gas flowing through the circulation path 53 is exhausted to the outside of the apparatus from the exhaust section 71 via the exhaust path 72 while adjusting the exhaust amount with the fan. As a result, a portion of the gas after the solvent has been recovered by the solvent recovery unit 4 is exhausted to the outside of the apparatus.

[0054] The amount of gas exhausted from exhaust unit 71 is adjusted by the fan so that it is at least greater than the amount supplied by supply unit 61. This makes it possible to create a negative pressure inside housing unit 21 relative to the outside of housing unit 21, thereby preventing gas from leaking out of housing unit 21.

[0055] The following describes the second drying unit 3. Note that detailed description of the same configuration as the first drying unit 2 will be omitted.

[0056] The second drying unit 3 is for heating and drying the coating film 11 formed on the substrate 1. As shown in Fig. 1, the second drying unit 3 in this embodiment has a housing 31 through which the substrate 1 passes, a second heating source 32 that heats the coating film 11 within the housing 31, and a second discharge section 33. Note that the housing 31 and the second discharge section 33 have the same configuration as the housing 21 and the first discharge section 23 of the first drying unit 2, and therefore detailed description thereof will be omitted.

[0057] The second heating source 32 is for directly heating the coating film 11 inside the housing 31. The second heating source 32 is a laser light source that irradiates a laser 34 such as an infrared laser (see FIGS. 2(a) and 2(b)).

[0058] 1, a plurality of second heating sources 32 are attached to the upper wall of the housing 31 within the housing 31, and the plurality of second heating sources 32 are arranged at predetermined intervals along the transport path of the substrate 1. Each second heating source 32 irradiates a laser 34 vertically downward as shown in FIG. 2(b).

[0059] Each second heating source 32 has an oscillator (not shown) that irradiates a laser beam 34 and a lens (not shown) that shapes the laser beam 34 into a predetermined shape. The oscillator irradiates the lens with the laser beam 34, so that the laser beam 34 shaped into a predetermined shape is irradiated onto the coating film 11. The predetermined shape here refers to a shape that allows the laser beam 34 to be irradiated across the entire width of the substrate 1, as shown in FIG. 2(a). As a result, each second heating source 32 irradiates the laser beam 34 across the entire width of the substrate 1. The substrate 1 is transported at a constant speed by the transport unit under the laser beam 34 irradiated across the entire width of the substrate 1 by each heating source 32, so that the entire coating film 11 is uniformly heated.

[0060] In this way, the second heating source 32 heats the coating film 11 directly without using a gas by irradiating the coating film 11 with the laser 34, and can therefore transfer more thermal energy to the coating film 11 than the first heating source 22, which transfers thermal energy to the coating film 11 via a gas. This allows the second heating source 32 to increase the temperature of the coating film 11 more rapidly than when the first heating source 22 heats the coating film 11.

[0061] Furthermore, the laser 34 irradiated by the second heating source 32 penetrates and passes through the interior of the coating film 11, where it is absorbed by the coating film 11 and converted into thermal energy. In other words, the second heating source 32 can heat the coating film 11 from the inside. As a result, the second heating source 32 can heat the coating film 11 from the inside, and therefore can increase the temperature of the coating film 11 more rapidly than when the first heating source 22 heats the coating film 11 from the surface.

[0062] Furthermore, since the second heating source 32 can directly heat the coating film 11 without using a gas, it is possible to heat the coating film 11 without heating a gas used to dilute the solvent vaporized from the coating film 11, as is done by the first heating source 22. As a result, the energy consumed when heating the coating film 11 with the second heating source 32 is less than the energy consumed when heating the coating film 11 with the first heating source 22.

[0063] On the other hand, the first heating source 22 heats a gas, which creates a high-temperature environment inside the housing 21 and heats the coating film 11, so that the coating film 11 can be heated from multiple directions. That is, the coating film 11 can also be heated from the back side of the substrate 1. Therefore, even if the substrate 1 bends or shifts in position while being transported by the transport mechanism, thermal energy can be applied to the coating film 11 from multiple directions. As a result, heating the coating film 11 with the first heating source 22 is less likely to cause unevenness in the temperature of the coating film 11 than heating the coating film 11 from one direction, as with the second heating source 32.

[0064] The second drying unit 3 is also provided with a supply unit 81 that supplies gas into the housing 31. The supply unit 81 is a supply source for supplying gas, and is connected to the housing 31 by a supply path 82 as shown in Fig. 1. A fan (not shown) is provided in the supply path 82, and the fan supplies gas from the supply unit 81 into the housing 31 via the supply path 82.

[0065] 1, the drying device 100 is provided with a heat exchange section 83 that performs heat exchange between gas discharged from the housing section 21 of the first drying unit 2 by the first discharge section 23 and gas supplied to the housing section 31 of the second drying unit 3 by the supply section 81. In this embodiment, the circulation path 52 and the supply path 82 intersect within the heat exchange section 83, and heat exchange is performed between the gas discharged from the housing section 21 of the first drying unit 2 by the first discharge section 23 and flowing through the circulation path 52 and the gas flowing through the supply path 82.

[0066] That is, the gas supplied to the housing 31 of the second drying unit 3 by the supply unit 81 is heated by the gas that has been heated by the first heating source 22 and that has heated the coating film 11 in the housing 21 of the first drying unit 2 through the heat exchanger 83. This makes it possible to maintain the temperature inside the housing 31 of the second drying unit 3 at a temperature higher than room temperature without providing the first heating source 21 in the second drying unit 3. This reduces the energy consumed when drying the coating film 11 and also prevents the solvent vaporized from the coating film 11 in the housing 31 of the second drying unit 3 from being cooled and liquefied. Note that a temperature higher than room temperature here refers to, for example, a temperature of about 40 to 60°C.

[0067] The second drying unit 3 is also provided with an exhaust section 91 that exhausts some of the gas within the housing section 31 to the outside of the apparatus. This exhaust section 91 is connected to a second exhaust section 33 of the housing section 31 by an exhaust path 92, as shown in FIG. 1. A fan (not shown) is provided in the exhaust path 92, and the gas within the housing section 31 is exhausted from the exhaust section 91 to the outside of the apparatus via the exhaust path 92 while the exhaust volume is adjusted by this fan. This allows the solvent vaporized from the coating film 11 within the housing section 31 to be exhausted to the outside of the apparatus together with the gas, thereby preventing the solvent vaporized from the coating film 11 from accumulating within the housing section 31.

[0068] The amount of gas exhausted from exhaust unit 91 is adjusted by the fan so that it is at least greater than the amount supplied by supply unit 81. This makes it possible to create a negative pressure inside housing unit 31 relative to the outside of housing unit 31, thereby preventing gas from leaking out of housing unit 31.

[0069] In addition, in order to control the progress of drying of the coating film 11, the drying device 100 divides the drying process of the coating film 11 by the first drying unit 2 and the second drying unit 3 into an early drying period, a middle drying period, and a late drying period, and controls the temperature of the coating film 11 for each region.

[0070] In this embodiment, the second drying unit 3 dries the coating film 11 in the early stage of drying. That is, as shown in Fig. 1, the second drying unit 3 is located upstream of the first drying unit 2, and the housing 31 of the second drying unit 3 is in communication with the housing 21 of the first drying unit 2a, and heats the coating film 11 before the first drying unit 2. The first drying unit 2 dries the coating film 11 in the middle and late stages of drying.

[0071] This will be explained in detail using Figure 3. Figure 3 is a diagram showing the relationship between the temperature of the coating film 11 and the content of the solvent in the coating film 11 in this embodiment, with solid lines A and B showing the case where the coating film 11 is heated by the drying apparatus 100 in this embodiment, and chain lines C and D showing the case where the coating film 11 is heated only by the first drying unit 2 as in a conventional drying apparatus.

[0072] The initial stage of drying is a region in which the temperature of the coating film 11 is preheated from room temperature to a predetermined temperature, and the solvent content in the coating film 11 remains almost constant, as shown by the solid line B in Figure 3. In other words, the initial stage of drying is a region in which almost no solvent evaporates from the coating film 11.

[0073] In this embodiment, the coating film 11 is heated in the early stage of drying by the second drying unit 3. That is, in the early stage of drying, the coating film 11 is heated by the second heating source 32, which can increase the temperature of the coating film 11 more rapidly than the first heating source 22. As shown by the solid line A and the chain line C in Figure 3, the temperature of the coating film 11 can be increased more rapidly than in the past, and the time required to heat the coating film 11 to a predetermined temperature can be shortened.

[0074] Furthermore, because the solvent hardly evaporates from the coating film 11 in the early stages of drying, there is no need to supply a large amount of gas to dilute the solvent into the housing 31 of the second drying unit 3, which heats the coating film 11 in the early stages of drying. Furthermore, because the second drying unit 3 can directly heat the coating film 11 using the second heat source 32, there is no need to supply gas to the housing 31 to heat the coating film 11, as in the first drying unit 2. Therefore, in this embodiment, only a small amount of gas used to ventilate the interior of the housing 31 of the second drying unit 3 is required from the supply unit 81, allowing for a significant reduction in the amount of gas used to dry the coating film 11 compared to conventional drying devices. This allows for a reduction in the energy consumed when drying the coating film 11 compared to conventional drying devices.

[0075] The middle drying stage is a period in which the temperature of the coating film 11 is maintained at a substantially constant temperature or gradually increased to allow the coating film 11 to dry. In this embodiment, the coating film 11 is heated by the first drying unit 2 during the middle drying stage. Specifically, the coating film 11 is heated by the first heating source 22, which is more effective at preventing unevenness in the temperature of the coating film 11 than the second heating source 32 during the middle drying stage. This makes it easier to maintain the temperature of the coating film 11 at a substantially constant temperature, as shown by the solid line A in Figure 3 . This allows the solvent content of the coating film 11 to evaporate from the coating film 11 at a constant rate, from content b to content c, as shown by the solid line B in Figure 3 . This allows the drying of the coating film 11 to proceed while controlling the coating film 11 to prevent it from drying too much.

[0076] The latter stage of drying is a region in which the temperature of the coating film 11 is again increased to dry the coating film 11. Here, in this embodiment, the first drying unit 2 heats the coating film 11 during the middle stage of drying. That is, during the latter stage of drying, the coating film 11 is heated by the first heating source 22, which can suppress unevenness in the temperature of the coating film 11 more effectively than the second heating source 32. Therefore, the solvent is evaporated from the coating film 11 at a constant rate, such as the content of the coating film 11 changing from content c to content d, as shown by the solid line B in FIG. 3 , and the coating film 11 can be heated while adjusting the temperature of the coating film 11 so as not to dry the coating film 11 too much. This allows the coating film 11 to dry without causing unevenness in the drying of the coating film 11.

[0077] As described above, in the drying apparatus 100 of this embodiment, the coating film 11 is heated by the second heat source 32 in the early stage of drying. This shortens the time required to heat the coating film 11 to a predetermined temperature compared to conventional drying apparatuses, as shown by the solid lines A and chain lines C in FIG. 3, and also shortens the time required to dry the coating film 11, as shown by the solid lines B and chain lines D in FIG. 3. This allows for a reduction in the energy consumed in drying the coating film 11 compared to conventional drying apparatuses. Furthermore, the coating film 11 is heated by the first heat source 22 in the middle and late stages of drying, which suppresses segregation of the binder in the coating film 11 during heating and prevents deformation of the coating film 11. In other words, the drying apparatus 100 of this embodiment shortens the time required to dry the coating film 11 while preventing deformation of the coating film 11.

[0078] Here, the second drying unit 3 in this embodiment is intentionally not provided with a solvent recovery unit 4. Specifically, the second drying unit 3 in this embodiment heats the coating film 11 in the early stages of drying when the solvent is unlikely to evaporate from the coating film 11 and solvent recovery is not necessary. For this reason, the second drying unit 3 is not provided with a solvent recovery unit 4. This reduces the cost of installing the equipment and the running cost of operating the equipment compared to when both the first drying unit 2 and the second drying unit 3 are provided with solvent recovery units 4.

[0079] 4, the second heating source 32 has a first heating section 32a that irradiates the coating film 11 with a laser 34 and a second heating section 32b that irradiates the coating film 11 with a laser 34 that is adjusted to have a lower output than the first heating section 32a. In this embodiment, of the multiple second heating sources 32, the second heating source 32 that first heats the coating film 11 is designated as the first heating section 32a, and the second heating source 32 that is arranged along the conveyance direction of the substrate 1 so as to heat the coating film 11 after the first heating section 32a is designated as the second heating section 32b. That is, in the second drying unit 3 in this embodiment, the coating film 11 is first heated by the first heating section 32a, which is adjusted to have a higher output of the laser 34 irradiated than the second heating section 32b, and then the coating film 11 is heated by the second heating section 32b, which is adjusted to have a lower output of the laser 34 irradiated than the first heating section 32a. This makes it possible to reduce the time required for drying the coating film 11 while suppressing unevenness in drying of the coating film 11.

[0080] A more specific explanation will be given below. If the second drying unit 3 only had a first heating section 32a in which the output of the irradiating laser 34 was adjusted to be high, and a plurality of these first heating sections 32a were arranged along the conveyance direction of the substrate 1 and each of the first heating sections 32a heated the coating film 11, the temperature of the coating film 11 could be rapidly increased to shorten the time required to dry the coating film 11, but the temperature of the surface of the coating film 11 would rise more rapidly than the temperature inside the coating film 11, resulting in a large temperature difference between the surface and inside of the coating film 11, which could result in uneven drying of the coating film 11.

[0081] In contrast, in the second drying unit 3 of this embodiment, the coating film 11 is first heated by the first heating section 32a, and then heated by the second heating section 32b, which has a laser 34 that is adjusted to have a lower output than the first heating section 32a. This allows the temperature of the surface of the coating film 11 to be raised more gradually than when the coating film 11 is heated only by the first heating section 32a. This allows the temperature of the coating film 11 to be raised more rapidly while reducing the temperature difference between the surface and the interior of the coating film 11. This therefore reduces uneven drying of the coating film 11 and shortens the time required to dry the coating film 11.

[0082] Furthermore, in the second drying unit 3, the coating film 11 is continuously heated by multiple second heating sources 32, i.e., the first heating section 32a and the second heating section 32b, thereby further shortening the time required to dry the coating film 11. Specifically, the temperature inside the housing section 31 does not rise significantly outside the range irradiated with the laser 34 from the second heating source 32, so the temperature of the coating film 11 may drop between the range irradiated with the laser 34 from the second heating source 32 in the housing section 31 and the time the coating film 11 is heated in the next housing section 21. In contrast, in the drying unit 3 of this embodiment, the coating film 11 is continuously heated by the first heating section 32a and the second heating section 32b, so heat can penetrate into the interior of the coating film 11, improving the heat retention of the coating film 11 after heating. This prevents the temperature of the coating film 11 from decreasing between when the coating film 11 is heated by the second drying unit 3 and when the coating film 11 is heated by the first drying unit 2, thereby further shortening the time required to dry the coating film 11.

[0083] Furthermore, the second heating section 32b in this embodiment is configured to irradiate the laser 34 over a wider irradiation range than the first heating section 32a in the conveyance direction of the substrate 1. In this embodiment, as shown in Fig. 4, more second heating sections 32b are provided than first heating sections 32a, and the second heating sections 32b are arranged along the conveyance direction of the substrate 1, thereby making the irradiation range of the laser 34 irradiated by the second heating sections 32b wider than that of the first heating sections 32a in the conveyance direction of the substrate 1. In this way, by widening the irradiation range of the laser 34 irradiated by the second heating sections 32b, the time for heat to penetrate into the coating film 11 by the second heating sections 32b can be increased, thereby further improving the heat retention of the coating film 11 after heating.

[0084] Furthermore, in the second drying unit 3 in this embodiment, the first heating section 32a and the second heating section 32b are arranged so that there is no gap between the lasers 34 irradiated by the first heating section 32a and the second heating section 32b in the conveyance direction of the substrate 1. This makes it possible to improve the heat retention of the coating film 11 after heating, compared to when a gap is left between the lasers 34 irradiated by the first heating section 32a and the second heating section 32b, and the lasers 34 are irradiated by each of the first heating section 32a and the second heating section 32b.

[0085] Furthermore, of the multiple second heating sections 32b, the second heating section 32b that heats the coating film 11 last is provided so that it can irradiate the laser 34 onto the coating film 11 located near the side wall on the exit side of the housing section 31, and it is preferable to irradiate the laser 34 so that the distance between the end of the irradiation range of the laser 34 by the second heating section 32b and the side wall on the exit side of the housing section 31 is as short as possible within a range where the laser 34 irradiated by the second heating section 32b does not irradiate the inner wall of the housing section 31. This shortens the time from when the coating film 11 is heated by the second drying unit 3 to when the coating film 11 is heated by the first drying unit 2, making it easier to prevent the temperature of the coating film 11 from decreasing between when the coating film 11 is heated by the second drying unit 3 and when the coating film 11 is heated by the first drying unit 2.

[0086] As described above, according to the drying device 100 of the above embodiment, the second heat source 32 can directly heat the coating film 11 formed on the substrate 1 passing through the housing 31 of the second drying unit 3, making it possible to heat the coating film 11 without heating the gas supplied into the housing 11 to dilute the solvent vaporized from the coating film 11. This makes it possible to reduce the energy consumed when drying the coating film 11 compared to conventional methods.

[0087] Furthermore, the second drying unit 3 heats the coating film 11 before the first drying unit 2, and therefore the coating film 11 can be directly heated by the second heating source 32 at a position where the solvent is less likely to evaporate from the coating film 11. Therefore, the second drying unit 3 can heat the coating film 11 while reducing the amount of gas supplied into the housing 31 to dilute the solvent that has evaporated from the coating film 11. This allows for further reduction in the energy consumed when drying the coating film 11.

[0088] Although the embodiments of the present invention have been described above in detail with reference to the drawings, the configurations and combinations thereof in each embodiment are merely examples, and additions, omissions, substitutions, and other modifications of the configurations are possible without departing from the spirit of the present invention. For example, in the above embodiment, the second heating source 32 heats the coating film 11 by irradiating it with a laser. However, this is not limited to this, as long as it can directly heat the coating film 11 by applying thermal energy to the coating film 11. For example, the second heating source 32 may heat the coating film 11 by irradiating it with microwaves, or the second heating source 32 may heat the coating film 11 by an infrared heater, an infrared lamp, induction heating, or dielectric heating.

[0089] Furthermore, in the above embodiment, an example has been described in which the second drying unit 3 heats the coating film 11 in the early stages of drying, but heating may also be performed in other regions. In this case, it is necessary to provide the second drying unit 3 with a solvent recovery unit 4 to recover the solvent vaporized from the coating film 11. Even when the second drying unit 3 is provided with the solvent recovery unit 4, the second drying unit 3 can directly heat the coating film 11 using the second heat source 32 without heating the gas circulating through the circulation path 5 as in the first drying unit 2, and therefore the energy consumed when heating the coating film 11 can be reduced compared to conventional methods.

[0090] 4 illustrates an example in which the second heating source 32 includes one first heating unit 32a and four second heating units 32b, but this is not limiting. In the above embodiment, the number of second heating units 32b is greater than the number of first heating units 32a, and the second heating units 32b are arranged along the transport direction of the substrate 1, thereby widening the irradiation range of the laser 34 emitted by the second heating units 32b compared to the first heating units 32a in the transport direction of the substrate 1. However, this is not limiting. For example, as illustrated in FIG. 5, the second heating units 32b may be configured to irradiate the laser 34 in such a manner that the irradiation range of the laser 34 emitted by each second heating unit 32b is wider than the irradiation range of the laser 34 emitted by the first heating unit 32a in the transport direction of the substrate 1. In this case, even if the second heating source 32 has the same number of first heating sections 32a and second heating sections 32b, the irradiation range of the laser 34 irradiated by the second heating section 32b can be wider than that of the first heating section 32a in the conveying direction of the substrate 1, as in the above embodiment.

[0091] In the above embodiment, the second heating source 32 has the first heating section 32a and the second heating section 32b, but the present invention is not limited to this. For example, the second heating sources 32 may be arranged along the transport direction of the substrate 1 to heat the coating film 11, with the output of the irradiated laser 34 adjusted to an extent that does not cause uneven drying of the coating film 11.

[0092] Furthermore, in the above embodiment, an example in which the second drying unit 3 includes the housing 31 has been described; however, the housing 31 need not be included. Alternatively, a gas containing a solvent heated by the second drying unit 3 and vaporized from the coating film 11 may be supplied from the inlet of the housing 21 located closest to the second drying unit 3. Specifically, when the second drying unit 3 includes the housing 31, the pressure inside the housing 21 is set lower than the pressure inside the housing 31, thereby supplying the gas inside the housing 21 to the housing 21. When the second drying unit 3 does not include the housing 31, the pressure inside the housing 21 is set lower than the pressure outside the housing 21 near the inlet of the housing 21, thereby supplying the gas present near the inlet of the housing 31 to the housing 21. In this way, the gas whose temperature has increased when the coating film 11 is heated by the second drying unit 3 can be supplied into the housing 21 and used to heat the coating film 11 inside the housing 21. Furthermore, the solvent heated by the second drying unit 3 and vaporized from the coating film 11 can be supplied from inside the housing 31 to inside the housing 21, thereby preventing the concentration of the solvent from increasing inside the housing 31. This makes it easier to prevent the solvent remaining inside the housing 31 from interfering with the heating of the coating film 11 by the second heating source 32.

[0093] In the above embodiment, an example in which only the second heating source 32 is provided in the second drying unit 3 has been described, but the first heating source 22 and the second heating source 32 may also be provided.

[0094] Furthermore, in the above embodiment, an example has been described in which the drying device 100 includes only one second drying unit 3, but it may include a plurality of second drying units.

[0095] In the above embodiment, the second heating source 32 has a plurality of second heating sources 32, but the second heating source 32 may have only one second heating source 32. In this case, the coating film 11 is heated by increasing the output of the laser irradiated by the second heating source 32.

[0096] Furthermore, in the above embodiment, an example has been described in which the applicator unit forms one coating film 11 in the width direction of the substrate 1, but multiple coating films 11 may be formed by the applicator unit along the width direction of the substrate 1 with a fixed interval between each coating film 11. Even in this case, the drying apparatus 100 in the above embodiment is configured to heat multiple coating films 11 by irradiating the entire width direction of the substrate 1 with a laser 34 using the second heating source 32. Note that it is also possible to provide the same number of second heating sources 32 as the number of coating films 11 formed on the substrate 1 and arrange them along the width direction of the substrate 1, and to heat each coating film 11 individually using each second heating source 32.

[0097] Furthermore, in the above embodiment, an example has been described in which the coating film 11 is formed on one side of the substrate 1 by the coating unit, but the coating film 11 may also be formed on both sides of the substrate 1 by the coating unit. In this case, the second drying unit 3 is configured to heat the coating film 11 formed on both sides of the substrate 1. That is, the second heating source 32 is provided so as to irradiate the laser 34 onto each of the coating films 11 formed on both sides of the substrate 1. For example, the second heating source 32 may be attached to each of the upper and lower walls of the housing 31 within the housing 31.

[0098] In the above embodiment, the heat exchanger 83 is used to maintain the temperature inside the housing 31 of the second drying unit 3 at or above room temperature. However, the present invention is not limited to this. For example, as shown in FIG. 6 , the supply unit 81 may supply the gas discharged from the housing 21 of the first drying unit 2 by the first discharge unit 23 into the housing 31 of the second drying unit 3. Specifically, as shown in FIG. 6 , the supply unit 81 is connected to the exhaust path 72, and the low-concentration gas is heated by the first heating source 22 in the first drying unit 2, heats the coating film 11 inside the housing 21, and then discharged from the housing 21 by the first discharge unit 23. The low-concentration gas from which the solvent has been recovered by the solvent recovery unit 4 is supplied into the housing 31 through the exhaust path 72, the supply unit 81, and the supply path 82.

[0099] That is, since the high-temperature gas after heating the coating film 11 in the housing portion 21 by the first heating source 22 is supplied to the housing portion 31 by the supply portion 81, it is possible to keep the temperature inside the housing portion 31 of the second drying unit 3 higher than the normal temperature without providing the first heating source 12 in the second drying unit 3. As a result, while suppressing the energy consumed when drying the coating film 11, it is possible to suppress the solvent vaporized from the coating film 11 from being cooled and liquefied inside the housing portion 31 of the second drying unit 3. When the concentration of the solvent contained in the gas is below the reference value inside the housing portion 21 of the first drying unit 2 that discharges the gas supplied to the housing portion 31 of the second drying unit 3 by the supply portion 81, the solvent may not be recovered by the solvent recovery unit 4. That is, the gas discharged from the inside of the housing portion 21 of the first drying unit 2 by the first discharge portion 23 may be directly supplied into the housing portion 31 of the second drying unit 3.

[0100] Also, the heat exchange portion 83 may not be provided. In this case, for example, the gas in the atmosphere may be directly supplied into the housing portion 31 of the second drying unit 3. That is, a gas at normal temperature may be supplied into the housing portion 31 of the second drying unit 3.

[0101] In the above embodiment, an example where the solvent contained in the coating liquid is NMP has been described, but it may be water.

Explanation of Signs

[0102] 100 Drying apparatus 1 Substrate 11 Coating film 2 First drying unit 2a First drying unit 2b First drying unit 2c First drying unit 21 Housing portion 22 First heating source 23 First discharge portion 3 Second drying unit 31 Housing portion 32 Second heating source 32a First heating portion 32b Second heating section 33 Second discharge section 34 Laser 4 Solvent Recovery Unit 41 Cooling section 42 Recovery Department 43 Recovery Route 44 Main body 5 Circulation path 51 Circulation route 52 Circulation path 53 Circulation path 61 Supply section 62 Supply route 71 Exhaust section 72 Exhaust duct 81 Supply section 82 Supply route 83 Heat exchange section 91 Exhaust section 92 Exhaust duct

Claims

1. A drying device including a housing portion through which a substrate having a coating film formed thereon passes, and a supply portion that supplies gas into the housing portion, and in which a first drying unit and a second drying unit that heat and dry the coating film within the housing portion are arranged side by side, the second drying unit is disposed at a position where the coating film is heated before the first drying unit; the first drying unit is provided with a first heating source as a heating source for the coating film, which indirectly heats the coating film by heating the gas to a temperature required to dry the coating film before it is supplied from the supply section to the housing section of the first drying unit; the second drying unit is provided with a second heating source as a heating source for the coating film, the second heating source directly heating the coating film in the housing of the second drying unit; The drying device is characterized in that the second heat source heats the coating film by irradiating the coating film with a laser.

2. 2. The drying device according to claim 1, wherein the second heat source irradiates the substrate with a laser beam over the entire width of the substrate.

3. 3. The drying device according to claim 1, wherein the laser emitted by the second heat source is an infrared laser.

4. the second heating source has a first heating section and a second heating section that apply thermal energy to the coating film, The drying device described in claim 1 or claim 2, characterized in that the second heating section is adjusted to have a smaller output of heat energy applied to the coating film than the first heating section, and heat energy is applied to the coating film after the first heating section.

5. The drying device described in claim 4, characterized in that the second heating section is set to have a wider range of heat energy applied to the coating film than the first heating section in the drying process direction in which heat energy is applied to the coating film in the order from the first heating section to the second heating section.

6. 6. The drying device according to claim 5, wherein a plurality of the second heating sections are provided, and the second heating sections are arranged in the drying processing direction.

7. the first drying unit is provided with an exhaust section that exhausts gas from within the housing section, A drying device as described in claim 1 or claim 2, characterized in that a heat exchange section is provided between the first drying unit and the second drying unit, which performs heat exchange between gas discharged from the housing section of the first drying unit by the exhaust section and gas supplied to the housing section of the second drying unit by the supply section.

8. the first drying unit is provided with an exhaust section that exhausts gas from within the housing section, 3. The drying device according to claim 1, wherein the supply unit supplies the gas discharged from the housing of the first drying unit by the discharge unit into the housing of the second drying unit.

9. 3. The drying device according to claim 1, wherein the pressure inside the housing of the first drying unit is set to be lower than the pressure inside the housing of the second drying unit.

10. The coating is formed on both sides of the substrate, 3. The drying device according to claim 1, wherein the second heat source is provided so as to be able to heat each of the coating films formed on both sides of the substrate.

Images