JP2019060505A - Drying method and dryer - Google Patents

Abstract

To efficiently dry a thin film formed on a substrate while containing an active substance, a solvent, and a binder, while preventing the binder present in the thin film from melting.SOLUTION: The drying method comprises an irradiation process of irradiating a thin film formed on a substrate while containing an active substance, a solvent, and a binder with far infrared light having a wavelength region, at which the infrared absorption rate of the solvent present in the thin film becomes maximum, and a cooling process of cooling the thin film to a temperature lower than the melting temperature of the binder in parallel with the irradiation process. Therefore, the binder present in the thin film can efficiently be dried while preventing the binder from melting.SELECTED DRAWING: Figure 6

Description

  The present invention relates to the drying technology of a coating film such as a chemical battery material formed on a substrate.

  In Patent Document 1, a slurry-like electrode material in which an active material and a solvent are mixed is coated on a belt-like base material to form a coating film, and the coating film is irradiated with far infrared rays from a heater to dry the coating film. An electrode manufacturing apparatus is shown. The said apparatus estimates the film thickness of the solvent in the coating film of an electrode material, and estimates the wavelength where the infrared absorptivity by a solvent becomes the largest with respect to the estimated film thickness. The device estimates the temperature of the heater for emitting infrared rays of the estimated wavelength, and whether the solvent boils with the combination of the estimated film thickness and the estimated heater temperature, the film thickness and the solvent boil Start based on the relationship between the temperature of the heater to start. If it is determined that the solvent does not boil, the device sets the heater temperature to the estimated temperature, while if it is determined that the solvent boils, the device has an infrared wavelength indicating the next highest absorption peak. Is newly estimated, the temperature of the heater emitting infrared light of the newly estimated wavelength is newly estimated, and it is again determined whether the solvent boils at the newly estimated temperature. The apparatus is intended to prevent boiling of the solvent by repeating the above process until the temperature of the heater at which the solvent does not boil is estimated.

JP, 2012-146848, A

  In the device of Patent Document 1, the boiling of the solvent can be suppressed by setting the heater to a temperature estimated not to cause the boiling of the solvent, but the radiant heat from the heater melts the binder in the electrode material. There is a problem that the performance of the manufactured electrode is degraded. Further, the apparatus also has a problem that the drying efficiency of the coating film is lowered without sufficient irradiation of far infrared rays of the wavelength having the highest absorption efficiency by the coating film.

  The present invention has been made to solve these problems, and a thin film formed on a substrate, containing an active material, a solvent and a binder, while suppressing the melting of the binder in the thin film. An object of the present invention is to provide a technology that can dry efficiently.

  In order to solve the above problems, the drying method according to the first aspect is a drying method for drying a thin film formed on a substrate, which contains an active material, a solvent and a binder, and it is based on the solvent An irradiation step of irradiating the thin film with far infrared rays having a wavelength range in which the absorptivity is maximum, and a cooling step of cooling the thin film to a temperature lower than the melting temperature of the binder in parallel with the irradiation step. Prepare.

  The drying apparatus according to the second aspect is a drying apparatus for drying a thin film formed on a substrate, containing an active material, a solvent, and a binder, and a wavelength range in which the absorption rate by the solvent is maximized The thin film according to the present invention includes: an irradiation unit which irradiates the thin film with far infrared rays, and a cooling unit which cools the thin film irradiated with the far infrared rays by the irradiation unit to a temperature lower than a temperature at which the binder melts.

  The drying device according to the third aspect is the drying device according to the second aspect, wherein the irradiation unit is disposed on the thin film side with respect to the base, and the cooling unit is with respect to the base It is arrange | positioned on the opposite side to the irradiation part.

  The drying device according to the fourth aspect is the drying device according to the second or third aspect, and further includes an irradiation unit cooling mechanism that cools the irradiation unit.

  The drying device according to the fifth aspect is the drying device according to any one of the second to fourth aspects, wherein the base material is in the form of a long strip, and the drying device is characterized in that It further comprises a moving unit for moving in the direction.

  The drying device according to a sixth aspect is the drying device according to the fifth aspect, wherein a plurality of the irradiation units are disposed along the moving direction of the base material by the moving unit, and among the plurality of irradiation units The cooling unit is disposed between the irradiation units adjacent to each other.

  According to the invention of the first aspect, the thin film is irradiated with far infrared rays having a wavelength range in which the absorption rate by the solvent is maximum in the irradiation step, and in the cooling step, the binder is melted in parallel with the irradiation step. The thin film is cooled below the Therefore, the thin film can be efficiently dried while suppressing the melting of the binder in the thin film.

  According to the invention of the second aspect, the irradiating unit irradiates the thin film with far infrared rays having a wavelength range in which the absorptance by the solvent is maximum, and the cooling unit is a thin film irradiated with far infrared rays by the irradiating unit. Is cooled below the temperature at which the binder melts. Therefore, the thin film can be efficiently dried while suppressing the melting of the binder in the thin film.

  According to the invention of the third aspect, the irradiation unit is disposed on the thin film side with respect to the substrate, and the cooling unit is disposed on the side opposite to the irradiation unit with respect to the substrate. It is possible to reduce the area required for the installation of the irradiation unit and the cooling unit in vision.

  According to the invention of the fourth aspect, since the irradiation part cooling mechanism cools the irradiation part, it is possible to suppress the radiant heat from the irradiation part.

  According to the invention of the fifth aspect, since the base material has a long strip shape and the moving part moves the base material in its longitudinal direction, the moving part is, for example, the unwinding roller of the base material and the winding roller And the drying device can be miniaturized.

  According to the invention of the sixth aspect, a plurality of irradiation units are disposed along the moving direction of the base material by the moving unit, and the cooling unit is disposed between the adjacent irradiation units among the plurality of irradiation units. The drying efficiency of the substrate can be improved.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows the whole structure of the coating-film formation system incorporating the drying apparatus which concerns on embodiment of this invention. It is a side schematic diagram which shows the structural example of the drying part of FIG. It is a side schematic diagram which shows the structural example of the infrared irradiation unit of FIG. 2, and a coating-film cooling unit. It is a figure which shows the absorptivity of the infrared rays by the solvent in a coating film in graphical form. FIG. 5 is a graphical representation of the radiation emittance of a black body. It is a flowchart which shows an example of operation | movement of a coating-film formation system. It is a flowchart which shows an example of operation | movement of a coating-film formation system.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

<1. Overall configuration of coating film forming system>
FIG. 1 is a view showing the overall configuration of a coating film forming system 1 incorporating a drying device according to the present invention. In FIG. 1 and the subsequent drawings, the dimensions and the numbers of the respective parts are exaggerated or simplified as necessary for easy understanding.

  The coating film forming system 1 applies a coating solution of an active material which is an electrode material on a metal foil as the substrate 5, and performs a drying process of the coating solution to form an electrode of a lithium ion secondary battery. It is an apparatus for manufacturing. The coating film forming system 1 includes a coating device 10, a drying unit 70, and a transport mechanism 80. The drying unit 70 and the transport mechanism 80 also operate as the drying device 150. Moreover, the coating-film formation system 1 is provided with the control part 90 which manages the whole system. Moreover, the coating-film formation system 1 is provided with the pump unit 15 which feeds the coating liquid of an electrode material to the coating apparatus 10, and the electrically equipped box (not shown) which accommodates a power supply etc. FIG.

  The substrate 5 is a metal foil that functions as a current collector of a lithium ion secondary battery. When manufacturing the positive electrode of a lithium ion secondary battery by the coating-film formation system 1, aluminum foil (Al) can be used as the base material 5, for example. Moreover, when manufacturing a negative electrode with the coating-film formation system 1, copper foil (Cu) can be used as the base material 5, for example. The base material 5 is a long sheet-like (long strip-like) metal foil, and the width and thickness thereof are not particularly limited. For example, the width is 600 mm to 700 mm, and the thickness is 10 μm to 20 μm. Can.

  The long base material 5 is delivered from the unwinding roller 81 and taken up by the take-up roller 82, whereby the coating device 10 and the drying unit 70 are conveyed in order. The transport mechanism 80 is configured to include the unwinding roller 81, the winding roller 82, and a plurality of auxiliary rollers 83. The number and the arrangement position of the auxiliary rollers 83 are not limited to the example shown in FIG. 1 and can be appropriately increased or decreased as needed. The transport mechanism 80 moves the substrate 5 along its longitudinal direction.

  The drying unit 70 performs a drying process on the coating film 7 of the coating liquid formed on the substrate 5 by the coating apparatus 10. The drying unit 70 heats the substrate 5 transported by the transport mechanism 80 to evaporate the solvent from the coating liquid and perform the drying process. The coating film forming system 1 is, for example, the downstream side of the coating device 10 in the transport direction of the substrate 5 and the upstream side of the drying unit 70 in the transport direction, and the coating film is applied. Even if it has a preheating part that raises the temperature gently, and an annealing part etc. that heats the coating film to a higher temperature on the downstream side of the transport direction with respect to the drying part 70 to remove distortion and residual stress in the film. Good.

The coating apparatus 10 includes a coating nozzle 11 and a backup roller 12. The coating nozzle 11 is supplied with a solution of an active material which is an electrode material from a pump unit 15. The coating nozzle 11 applies the solution to the surface of the base material 5 traveling in a state of being pressed and supported by the backup roller 12. When the positive electrode is manufactured by the coating film forming system 1, for example, lithium cobaltate (LiCoO ₂ ), which is a positive electrode active material, carbon (a conductive aid) is used as a coating liquid for the positive electrode material from the coating nozzle 11 C) A mixture of polyvinylidene fluoride (PVDF) as a binder and N-methyl-2-pyrrolidone (NMP) as a solvent is applied to the substrate 5. Instead of lithium cobaltate, lithium nickelate (LiNiO ₂ ), lithium manganate (LiMn ₂ O ₄ ), lithium iron phosphate (LiFePO ₄ ) or the like can also be used as a positive electrode active material.

On the other hand, when the negative electrode is manufactured by the coating film forming system 1, as a coating liquid for the negative electrode material from the coating nozzle 11, for example, graphite (graphite) which is a negative electrode active material, PVDF which is a binder, solvent The mixture solution of NMP, which is Instead of graphite, hard carbon, lithium titanate (Li ₄ Ti ₅ O ₁₂ ), silicon alloy, tin alloy, or the like can be used as the negative electrode active material. The coating liquid of these positive electrode material and negative electrode material is a slurry in which solid (fine particles) are dispersed.

  As the coating nozzle 11, the slit nozzle which provided the slit-like discharge outlet along the width direction of the base material 5 can be used. The coating nozzle 11 discharges the coating liquid of the electrode material supplied from the pump unit 15 from the discharge port 11 a and applies it to the traveling base material 5, and forms a coating film of the electrode material on the surface of the base material 5. Do. The pump unit 15 includes a supply valve (not shown) that is opened and closed under the control of the control unit 90. The supply valve repeatedly switches between delivery / stop from the pump unit 15 to the coating nozzle 11. The timing of the opening and closing of the supply valve is appropriately controlled by the control unit 90. The coating liquid is intermittently applied to a predetermined position of the substrate 5 with a predetermined width by repeating the switching between the opening and closing of the supply valve.

  The thickness of the coating film of the electrode material formed on the surface of the substrate 5 in the coating apparatus 10 is, for example, 100 μm to 200 μm in the state before drying, and usually 10 times or more the thickness of the substrate 5 It is. Even if such a relatively thick coating film is formed, since the electrode material is a high viscosity slurry having a viscosity of 1 Pa · s (pascal second) or more, no dripping or the like occurs immediately. The substrate 5 on which the coating film of the electrode material is formed by the coating apparatus 10 is transported to the drying unit 70 by the transport mechanism 80, and the coating film is subjected to the drying process.

<2. Infrared irradiation unit 51>
FIG. 2 is a schematic side view showing a configuration example of the drying unit 70 of the drying device 150. As shown in FIG. The drying device 150 dries the coating 7 formed on the substrate 5 including the active material, the solvent, and the binder.

  FIG. 3 is a schematic side view showing a configuration example of the infrared irradiation unit 51 and the coating film cooling unit 52. As shown in FIG.

  As shown in FIG. 2, the drying unit 70 includes a plurality of (two in FIG. 2) infrared irradiation units 51. The plurality of infrared irradiation units 51 are disposed along the moving direction of the substrate 5 by the transport mechanism 80. Further, the infrared irradiation unit 51 is disposed on the side of the coating film 7 with respect to the substrate 5.

  The infrared irradiation unit 51 shown in FIG. 3 includes a far-infrared heater 60. The far-infrared heater 60 is housed in a box-like housing 64. The surface 64 a of the housing 64 facing the coating film 7 is made of, for example, quartz glass or the like. Thereby, the attenuation of the far infrared radiation energy emitted by the far infrared heater 60 can be suppressed.

  The far infrared heater 60 is a plate type far infrared heater. The far infrared heater 60 includes, for example, a plate-like member 61 made of aluminum and a rod-like heater 62 embedded in the plate-like member 61. A far infrared radiation plate 63 made of metal oxide ceramic or the like is attached to one surface of the plate member 61 by melting or the like. The rod-shaped heater 62 has, for example, a rod shape having a circular cross section, and penetrates the plate-like member 61 along the width direction of the substrate 5. Both ends of the rod-like heater 62 are exposed from the plate-like member 61 respectively.

  The rod-shaped heater 62 includes, for example, a metal outer cylinder (not shown), a heating element (not shown), a connection terminal (not shown) connected to the heating element, and the like. The heating element is spirally swirled and extends in the longitudinal direction of the rod-shaped heater 62. The heating element is supported in the outer cylinder of the rod-like heater 62 in an electrically insulated state from the outer cylinder by insulating powder such as magnesium oxide. When the rod-like heater 62 is energized to generate heat, the far infrared radiation plate 63 is also heated. As a result, infrared rays are emitted from the heated far infrared radiation plate 63. The coating 7 is heated by the infrared light. A rod type may be employed as the far infrared heater 60.

  The infrared irradiation unit 51 further includes an irradiation unit cooling mechanism 53. The irradiation part cooling mechanism 53 cools the infrared irradiation unit 51, more specifically, the far infrared heater 60 of the infrared irradiation unit 51.

  The irradiation part cooling mechanism 53 includes a cold air blower 65, and a pipe 66 connecting the inside of the housing 64 and the cold air blower 65 in communication. The cold air blowing unit 65 feeds dry air at normal temperature into the housing 64 through the pipe 66. The dry air supplied into the housing 64 flows along the periphery of the far-infrared heater 60 to cool the far-infrared heater 60. The dry air that has cooled the far infrared heater 60 is discharged to the outside of the housing 64 from the pipe 67 connected to the housing 64 in communication.

  Although the drying unit 70 of the drying apparatus 150 includes the plurality of infrared irradiation units 51 in the example of FIG. 2, the drying unit 70 may include one infrared irradiation unit 51. Moreover, in the example of FIG. 3, although the infrared irradiation unit 51 is equipped with the irradiation part cooling mechanism 53, the infrared irradiation unit 51 does not need to be equipped with the irradiation part cooling mechanism 53. FIG.

<3. About the wavelength of far infrared rays emitted by the far infrared heater 60>
FIG. 4 is a graph showing the infrared absorptivity of the solvent in the coating film 7. FIG. 4 shows the relationship between the wavelength of infrared rays and the absorptivity of infrared rays by the solvent in the coating 7 by changing the film thickness of the coating 7 to two values of 10 μm and 200 μm, and a graph showing the measurement results It is. NMP is employed as the solvent. In the graph of FIG. 4, the measurement result in the case where the wavelength is 3 μm or less is disturbed by the measurement error. The film thickness of the coating 7 formed on the substrate 5 is often 100 μm to 200 μm or less.

  FIG. 5 is a graphical representation of the spectral radiance of a black body. The graph of the spectral radiation emittance of the far-infrared heater 60 has substantially the same shape as the graph of FIG. 5 and has a slightly smaller value than the graph of FIG. 5, but the peak wavelengths of these graphs are approximately the same Therefore, the wavelength of the far infrared radiation emitted by the far infrared heater 60 will be examined based on FIG.

  As shown in FIG. 5, as the temperature of the far-infrared heater 60 increases, the radiant energy increases as a whole. The peak value of the radiant energy moves to the short wavelength side as the temperature of the far-infrared heater 60 rises.

  In order to dry the coating 7 efficiently, the absorption of the far infrared by the solvent in the coating 7 is substantially uniform at each position in the thickness direction of the coating 7 as the wavelength of the far infrared radiation, Moreover, it is desirable that the energy of infrared rays be as high as possible.

  As shown in FIG. 4, peaks of infrared absorptivity by NMP exist at wavelengths of 3.5 μm, 6 μm, and 9 μm.

  In the case where the wavelength is 6 μm, when the infrared rays reach a film thickness of 10 μm from the surface of the coating 7, almost all of the infrared rays are absorbed by the coating 7 and the infrared rays do not reach deeper than 10 μm. For this reason, it is not preferable to use far infrared light having a wavelength of 6 μm.

  When the wavelength is 9 μm, 50% of the infrared light is absorbed when it reaches a depth of 10 μm from the surface of the coating film 7 and about 100% is absorbed when it reaches a depth of 200 μm. From this, the absorptivity at each depth is improved as compared to the case where the wavelength is 6 μm. However, as shown in the graph of FIG. 5, when the wavelength is 9 μm, the energy of infrared rays is small, so that the drying efficiency of the solvent is deteriorated. For this reason, it is not preferable to use far-infrared light having a wavelength of 9 μm.

  When the wavelength is 3.5 μm, about 30% is absorbed when the infrared ray reaches a depth of 10 μm from the surface of the coating 7 and about 100% is absorbed when the depth reaches 200 μm. From this, the uniformity of the absorptivity at each depth is improved as compared to the case where the wavelength is 9 μm.

  Further, as shown in the graph of FIG. 5, when the wavelength is 3.5 μm, the infrared radiation energy is also close to the maximum value.

  Therefore, in order to efficiently dry the coating film 7 containing NMP as a solvent, it is preferable to set the wavelength of far infrared radiation irradiated by the far infrared heater 60 to about 3.5 μm, for example, 3 μm to 4 μm. Thereby, the infrared irradiation unit 51 irradiates the coating film 7 with far infrared light having a wavelength range (3 μm to 4 μm) at which the absorptivity by NMP as a solvent is maximum.

<4. Measures for deterioration of binder>
As shown in the graph of FIG. 5, assuming that the temperature of the far infrared heater 60 is, for example, about 400 ° C. to 500 ° C., the radiant energy in the wavelength range of 3 μm to 4 μm approaches the peak value of the radiant energy. Its absolute value is also large enough.

  From this, from the viewpoint of improving the drying efficiency of the coating film 7, the temperature of the far-infrared heater 60 is, for example, 400 to set the wavelength of the infrared (far-infrared) emitted by the far-infrared heater 60 to 3 .mu.m to 4 .mu.m. It turns out that it is preferable to set it as about -500 degreeC.

  However, when the far-infrared heater 60 is heated to such a high temperature, the melting point of PVDF which is a binder contained in the coating 7 is, for example, 140 ° C. to 180 ° C. The radiant heat may heat the PVDF in the coating 7 and melt it beyond the melting point.

  In this case, the coating film 7 is then cooled to deteriorate the performance of the generated electrode. As a cause of this, for example, it is considered that the uniformity of the active material in the coating film 7 is deteriorated due to the melting of the PVDF.

  Therefore, in the drying device 150, as shown in FIG. 2, the drying unit 70 includes a plurality of (six in FIG. 2) coating film cooling units 52.

<5. Coating film cooling unit 52>
The drying unit 70 further includes a plurality of (6 in the example of FIG. 2) coating film cooling units 52. The coating film cooling unit 52 cools the coating film 7 irradiated with far infrared rays by the infrared irradiation unit 51 to a temperature at which the binder (specifically, for example, PVDF) melts.

  As shown in FIG. 3, the coating film cooling unit 52 is connected in communication with a cold air blower 71 for supplying dry air at normal temperature, a pipe 72 for guiding the dry air supplied by the cold air blower 71, and the pipe 72 to communicate the dry air. It has a box-like cold air blowing portion 73 introduced into the inside from the pipe 72. A plurality of injection holes (not shown) are formed on the surface of the cold air blowout portion 73 on the side of the base material 5. The dry air introduced into the cold air blowout unit 73 is jetted from the plurality of jet holes to the substrate 5 side.

  In the example of FIG. 2, two coating film cooling units 52 are disposed on the side of the coating film 7 with respect to the substrate 5, that is, on the infrared irradiation unit 51 side. Each of the two coating film cooling units 52 is disposed between adjacent coating film cooling units 52 among the plurality of coating film cooling units 52. In the two coating film cooling units 52, the cold air blowing unit 73 directly jets dry air (cold air) onto the coating film 7 on the substrate 5 to cool the coating film 7.

  Further, among the six coating film cooling units 52, the four coating film cooling units 52 are disposed on the opposite side of the substrate 5 to the infrared irradiation unit 51. In the four coating film cooling units 52, the cold air blowing unit 73 directly jets dry air to the substrate 5. The cold air blowing portion 73 indirectly cools the coating film 7 formed on the side opposite to the coating film cooling unit 52 with respect to the base material 5 via the base material 5.

  In the example of FIG. 2, the drying unit 70 includes a plurality of coating film cooling units 52, but the drying unit 70 may include one coating film cooling unit 52. Moreover, in the example of FIG. 2, although the drying part 70 is equipped with the coating film cooling unit 52 in the both sides of the base material 5, you may equip the coating film cooling unit 52 only in any one side.

<6. Operation of Coating Film Forming System 1 (Drying Device 150)>
FIG. 6, FIG. 7 is a flowchart which shows an example of operation | movement of the coating-film formation system 1 (drying apparatus 150).

  Hereinafter, the operation of the coating film forming system 1 (drying apparatus 150) will be described according to the flowcharts of FIGS. 6 and 7.

  In step S10 of FIG. 6, the transport mechanism 80 rotates the unwinding roller 81 and the winding roller 82 to supply the base material 5 wound around the unwinding roller 81 to the winding roller 82 side. Thereby, the transport mechanism 80 starts transport of the substrate 5 along a predetermined transport path.

  In step S <b> 20, the coating film forming system 1 discharges the coating liquid from the coating nozzle 11 onto one surface of the substrate 5 to start the formation of the coating film 7 on the substrate 5. As described above, the coating nozzle 11 intermittently discharges the coating liquid.

  In step S30, the infrared irradiation unit 51 of the drying unit 70 starts irradiation of far infrared radiation. As described above, the infrared irradiation unit 51 irradiates the far-infrared ray having a wavelength range in which the absorptivity of the solvent in the coating film 7 is maximum, to the coating film 7 conveyed to the drying unit 70. Specifically, the far-infrared heater 60 (far-infrared radiation plate 63) is set to a preset temperature (for example, a temperature of 400 ° C. to 500 ° C.), and the absorptivity by the solvent in the coating film 7 is maximized Irradiate infrared rays (far infrared rays) having a wavelength range (for example, 3 μm to 4 μm). The control unit 90 stores in advance the relationship between the amount of energization of the rod heater 62 of the far infrared heater 60 and the temperature of the far infrared radiation plate 63 in the internal storage device, and based on the relationship, the far infrared radiation The temperature of the radiation plate 63 is controlled. 4. The wavelength at which the absorptivity by the solvent in the coating film 7 is maximum (for example, 3.5 μm) and the wavelength giving the peak of the radiation energy emitted by the far infrared heater 60 (for example, at 400 ° C. for black body radiation) It is preferable that the temperature of the far-infrared heater 60 (far-infrared radiation plate 63) be controlled so that the difference with 3 μm is preferably not more than 1 μm.

  In addition, the drying device 150 may cool the far-infrared heater 60 in the housing 64 by starting the supply of the dry air from the irradiation unit cooling mechanism 53 in parallel with the energization of the far-infrared heater 60.

  In step S40, the coating film cooling unit 52 starts to jet cold air to start cooling the coating film 7 formed on the substrate 5. The film cooling unit 52 cools the film 7 below the temperature at which the binder contained in the film 7 melts.

  When the process of step S40 is started, the process is transferred to step S110 of FIG.

  In step S110, for example, the control unit 90 acquires a setting parameter for setting an air volume of dry air at normal temperature, which is cold air, based on recipe information and the like. The said recipe information etc. are previously input into the control part 90, and are memorize | stored in the memory | storage device in the control part 90. FIG. The setting parameters are, for example, the temperature of the far-infrared heater 60 (far-infrared radiation plate 63), the film thickness of the coating 7, the transport speed of the coating 7, and the like.

  In step S120, the control unit 90 sets the air volume of dry air (cold air) at normal temperature supplied from the coating film cooling unit 52 based on the setting parameter acquired in step S110. The air volume is set to an air volume that can cool the coating film 7 below the temperature at which the binder in the coating film 7 melts. The relationship between the air volume of the dry air supplied by the coating film cooling unit 52 and the temperature of the coating film 7 (binder) under the set parameters is acquired in advance and stored in the storage device in the control unit 90. There is. The control unit 90 sets the flow rate of dry air with reference to this relationship.

  When the solvent is NMP and the binder is PVDF, the temperature of the coating 7 is preferably 100 ° C. or more and less than 140 ° C. (an example of the melting point of PVDF). The temperature of the coating 7 is preferably below the melting point of the binder and as close as possible to the melting point.

  In step S130, the control unit 90 controls the cold air blowing unit 71 to start the supply of dry air from the coating film cooling unit 52 with the air volume set in step S120. Thus, the process proceeds to step S50 of FIG.

  In step S50, when the formation of the coating film 7 according to the recipe is completed, the coating film forming system 1 ends the formation of the coating film 7 on the substrate 5 according to the control of the control unit 90.

  In step S60, the infrared irradiation unit 51 stops the energization of the rod heater 62 of the far-infrared heater 60, and ends the irradiation of the far-infrared radiation from the far-infrared radiation plate 63.

  In step S <b> 70, the coating film cooling unit 52 stops the injection of the dry air to complete the cooling of the coating film 7.

  In step S80, the transport mechanism 80 stops the unwinding roller 81 and the winding roller 82, and terminates the transport of the base material 5. This completes the operation of FIG.

  According to the drying method according to the present embodiment as described above, far infrared rays having a wavelength range in which the absorptivity by the solvent is maximum are irradiated to the coating film 7 in the irradiation step, and parallel to the irradiation step in the cooling step. The coating film 7 is cooled below the temperature at which the binder melts. Therefore, the coating film 7 can be efficiently dried while suppressing the melting of the binder in the coating film 7.

  Moreover, according to the drying apparatus concerning this embodiment comprised as mentioned above, the infrared irradiation unit 51 irradiates the far infrared rays which have a wavelength range where the absorption factor by a solvent becomes the largest to the coating film 7, The cooling unit 52 cools the coating film 7 irradiated with far infrared rays by the infrared irradiation unit 51 to a temperature lower than the temperature at which the binder melts. Therefore, the coating film 7 can be efficiently dried while suppressing the melting of the binder in the coating film 7.

  Further, according to the drying device according to the present embodiment, the infrared irradiation unit 51 is disposed on the side of the coating film 7 with respect to the substrate 5, and the coating film cooling unit 52 is the same as the infrared irradiation unit 51 relative to the substrate 5. Since it arrange | positions on the opposite side, the area | region required for installation of the infrared irradiation unit 51 and the coating-film cooling unit 52 in planar view of the base material 5 can be made small.

  Further, according to the drying device according to the present embodiment, since the irradiation part cooling mechanism 53 cools the infrared irradiation unit 51, the radiant heat from the infrared irradiation unit 51 can be suppressed.

  Further, according to the drying device according to the present embodiment, since the base material 5 has a long strip shape and the transport mechanism 80 moves the base material 5 in the longitudinal direction, the transport mechanism 80 is, for example, of the base material 5 By providing the unwinding roller 81 and the winding roller 82, the drying device can be miniaturized.

  Further, according to the drying device according to the present embodiment, a plurality of infrared irradiation units 51 are disposed along the moving direction of the base material 5 by the transport mechanism 80, and the infrared irradiation units 51 adjacent to each other among the plurality of infrared irradiation units 51. Since the coating film cooling unit 52 is disposed between them, the drying efficiency of the substrate 5 can be improved.

  Although the present invention has been shown and described in detail, the above description is illustrative and not restrictive in all aspects. Therefore, in the present invention, within the scope of the invention, the embodiment can be appropriately modified or omitted.

DESCRIPTION OF SYMBOLS 1 coating-film formation system 10 coating apparatus 11 coating nozzle 11a discharge outlet 12 backup roller 5 base material 51 infrared irradiation unit (irradiation part)
52 Coating film cooling unit (cooling unit)
53 Irradiated part cooling mechanism 60 Far infrared heater 62 Bar heater 63 Far infrared radiation plate 65, 71 Cold air blower 7 Coating film (thin film)
70 drying unit 73 cold air blowing unit 80 transport mechanism (moving unit)
81 Take-out roller 82 Take-up roller 83 Auxiliary roller 90 Control unit

Claims (6)

A drying method for drying a thin film formed on a substrate, comprising an active material, a solvent and a binder,
Irradiating the thin film with far infrared rays having a wavelength range in which the absorption rate by the solvent is maximized;
In parallel to the irradiation step, a cooling step of cooling the thin film to a temperature lower than the melting temperature of the binder;
And drying method. A drying apparatus for drying a thin film formed on a substrate, comprising an active material, a solvent and a binder,
An irradiation unit which irradiates the thin film with far infrared rays having a wavelength range in which the absorption rate by the solvent is maximized;
A cooling unit configured to cool the thin film irradiated with far infrared rays by the irradiation unit to a temperature lower than a melting temperature of the binder;
A dryer comprising: The drying apparatus according to claim 2, wherein
The irradiation unit is disposed on the thin film side with respect to the base material,
The drying device, wherein the cooling unit is disposed on the side opposite to the irradiation unit with respect to the base material. The drying apparatus according to claim 2 or 3, wherein
The drying device, further comprising: an irradiation unit cooling mechanism that cools the irradiation unit. The drying apparatus according to any one of claims 2 to 4, wherein
The base material is a long strip,
The drying device
The drying device, further comprising a moving unit that moves the substrate in its longitudinal direction. The drying apparatus according to claim 5, wherein
A plurality of the irradiation units are disposed along the moving direction of the base material by the moving unit;
The drying device, wherein the cooling unit is disposed between irradiation units adjacent to each other among the plurality of irradiation units.

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