WO2014168229A1

WO2014168229A1 - Drying furnace

Info

Publication number: WO2014168229A1
Application number: PCT/JP2014/060455
Authority: WO
Inventors: 雄樹藤田; 良夫近藤
Original assignee: 日本碍子株式会社
Priority date: 2013-04-11
Filing date: 2014-04-11
Publication date: 2014-10-16
Also published as: TW201510451A

Abstract

A drying furnace (10) provided with: an infrared-ray heater (30); a selectively reflective layer (37) that is positioned, within a furnace body (12), between a filament (31) and a coating film (82), reflects at least part of an infrared ray having a wavelength of less than 2μm, and transmits at least part of an infrared ray having a wavelength of 2-4μm; and an infrared-ray absorbing plate (70) that is positioned within the furnace body (12) at the opposite side of the filament (31) to the selectively reflective layer (37), and can absorb at least part of an infrared ray having a wavelength of less than 2μm. The infrared-ray heater (30) includes a second outer tube (35) that transmits at least part of an infrared ray having a wavelength of 2-4μm, and surrounds the filament (31). At least one of the inner peripheral surface and the outer peripheral surface of the second outer tube (35) includes the selectively reflective layer (37) in a region containing the opposite side of the filament (31) to the infrared-ray absorbing plate (70).

Description

drying furnace

The present invention relates to a drying furnace.

Conventionally, a drying furnace for drying an object to be dried such as a coating film using an infrared heater is known. For example, Patent Literature 1 describes a drying furnace using an infrared heater including a heating element, and an inner tube and an outer tube surrounding the heating element. In this drying furnace, the inner tube and the outer tube of the infrared heater function as a filter that transmits infrared light having a wavelength of 3.5 μm or less and absorbs infrared light having a wavelength exceeding 3.5 μm. Infrared rays having a wavelength of 3.5 μm or less are said to be excellent in ability to break hydrogen bonds, and it is said that infrared rays having this wavelength can be radiated to an object to be dried to efficiently perform drying.

Japanese Patent No. 4790092

Incidentally, when drying is performed in a drying furnace using such an infrared heater, infrared rays having a wavelength of less than 2 μm may be emitted from the infrared heater. When infrared rays having a wavelength of less than 2 μm are emitted, the infrared rays may overheat the furnace body or the drying object of the drying furnace, and the drying object may be overheated. When the drying target is overheated, for example, a large amount of air for cooling is required, and the energy consumption during drying may increase.

The present invention has been made to solve such a problem, and has as its main object to further suppress overheating of an object to be dried by infrared rays having a wavelength of less than 2 μm from an infrared heater.

The drying furnace of the present invention is
A furnace body for drying the object to be dried;
An infrared heater having a heating element disposed in the furnace and emitting an electromagnetic wave including infrared;
Selective reflection that is disposed between the heating element and the object to be dried in the furnace, reflects at least part of infrared rays having a wavelength of less than 2 μm, and transmits at least part of infrared rays having a wavelength of 2 μm to 4 μm. Body,
An infrared absorber disposed in the furnace body on the side opposite to the selective reflector as viewed from the heating element and capable of absorbing at least part of infrared rays having a wavelength of less than 2 μm;
It is equipped with.

In the drying furnace of the present invention, when an electromagnetic wave including infrared rays is radiated from the heating element of the infrared heater, the infrared rays having a wavelength of less than 2 μm out of the electromagnetic waves are reflected by the selective reflector. Is done. Therefore, it can suppress that the infrared rays with a wavelength of less than 2 μm linearly reach the drying target side from the heating element. Moreover, the infrared light reflected by the selective reflector is radiated from the selective reflector toward the heating element, but this is absorbed by the infrared absorber. Therefore, it can also be suppressed that the infrared rays after being reflected by the selective reflector are further reflected by the furnace body and the like and reach the drying target side. As described above, it is possible to further suppress overheating of an object to be dried by infrared rays having a wavelength of less than 2 μm from the infrared heater. In addition, since the infrared rays having a wavelength of 2 μm to 4 μm emitted from the infrared heater can pass through the selective reflector and reach the drying target side, the infrared drying target can be dried. In this case, the selective reflector preferably transmits at least a part of infrared rays having a wavelength of 2 μm to 3.5 μm. Infrared rays having a wavelength of 3.5 μm or less are excellent in the ability to break hydrogen bonds in molecules such as water and solvents, so that the selective reflector can pass through this to dry the object to be dried more efficiently. . The selective reflector may be capable of reflecting not only infrared rays having a wavelength of less than 2 μm but also at least a part of electromagnetic waves having a wavelength shorter than 0.7 μm and shorter than infrared rays. In this case, the infrared absorber may be capable of absorbing at least a part of an electromagnetic wave with a wavelength shorter than 0.7 μm and shorter than 0.7 μm. The selective reflector and the infrared absorber may be in the form of a layer (film) formed on the surface of another member, or may be in the form of an independent member.

In this case, it is preferable that the selective reflector has a higher transmittance of infrared light having a wavelength of 2 to 4 μm than that of infrared light having a wavelength of less than 2 μm. “The transmittance of infrared light having a wavelength of 2 to 4 μm is higher than the transmittance of infrared light having a wavelength of less than 2 μm” means that the total transmittance of infrared light having a wavelength of 2 to 4 μm is larger than the total transmittance of infrared light having a wavelength of less than 2 μm. In addition to the case where the rate is high, the case where the wavelength range in which the transmittance is higher than the total transmittance of infrared rays having a wavelength of less than 2 μm exists in the range of 2 to 4 μm is also included. For example, the selective reflector may have a total transmittance of infrared light having a wavelength of less than 2 μm of 20% or less and a total transmittance of infrared light having a wavelength of 2 to 4 μm of 80% or more. The selective reflector may have a total transmittance of infrared rays having a wavelength of 2 to 3.5 μm of 80% or more.

In the drying furnace of the present invention, the infrared heater includes a tubular member that transmits at least a part of infrared rays having a wavelength of 2 μm to 4 μm and surrounds the heating element. The tubular member has an inner peripheral surface and an outer peripheral surface. The selective reflector may be provided in a region including the side opposite to the infrared absorber as viewed from the heating element. In this case, it is possible to further suppress overheating of the drying target due to infrared rays having a wavelength of less than 2 μm from the infrared heater without arranging the selective reflector as a member different from the infrared heater in the furnace.

In this case, the infrared heater transmits a first tube that transmits at least part of infrared rays having a wavelength of 2 μm to 4 μm and surrounds the heating element, and a second tube that is the tubular member surrounding the heating element and the first tube. The first tube has an infrared ray having a wavelength of 2 μm to 4 μm in a region including at least one of an inner peripheral surface and an outer peripheral surface including a side opposite to the drying target when viewed from the heating element. You may have the reflection layer which reflects at least one part. In this way, among the electromagnetic waves radiated from the heating element of the infrared heater in the direction opposite to the object to be dried, infrared rays having a wavelength of 2 μm to 4 μm are reflected by the reflective layer. Therefore, infrared rays having this wavelength can be efficiently irradiated onto the object to be dried, and the drying efficiency is improved.

The drying furnace of the present invention comprises a partition that partitions the space in which the infrared heater is disposed and the space in which the drying object is disposed in the furnace body, and transmits at least part of infrared rays having a wavelength of 2 μm to 4 μm. The partition may have the selective reflector. In this way, the space in which the infrared heater is disposed and the space in which the drying target is disposed are partitioned, so that the former space, objects in the space, furnace bodies facing the space, etc. are less than 2 μm in wavelength. Even when heated by infrared rays, the object to be dried is not easily heated. Therefore, it is possible to further suppress overheating of the drying target due to infrared rays having a wavelength of less than 2 μm from the infrared heater. Here, “the partition has the selective reflector” means that the entire partition is a selective reflector. The partition may have a selective reflector on the entire surface.

In the drying furnace of the present invention having the above-described partition, the furnace body may have the infrared absorber on the inner peripheral surface. If it carries out like this, the infrared rays reflected by the selective reflector can be absorbed with an infrared absorber, without arrange | positioning an infrared absorber as an independent member in a furnace body.

In the drying furnace of the present invention, the infrared absorber may have a refrigerant flow path through which a refrigerant can flow. In this way, since the infrared absorber can be cooled with the refrigerant, the infrared absorber can further suppress overheating by absorbing infrared rays, and the overheating of the infrared absorber has an adverse effect on the drying target (for example, overheating of the drying target). Giving more control.

1 is a longitudinal sectional view of a drying furnace 10. FIG. FIG. 2 is an AA cross-sectional view showing a cross section of the infrared heater 30 and the infrared absorption plate 70 of FIG. 1. It is explanatory drawing which shows an example of the wavelength characteristic of the infrared rays radiated | emitted from the infrared heater. It is a longitudinal cross-sectional view of the drying furnace 110 of the modification.

Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a longitudinal sectional view of a drying furnace 10 according to an embodiment of the present invention. The drying furnace 10 uses an infrared ray to dry the coating film 82 applied on the sheet 80 as an object to be dried, and the furnace body 12, the air supply device 20, the exhaust device 25, and the infrared heater 30. And an infrared absorption plate 70 and a controller 90. Moreover, the drying furnace 10 includes a roll 17 provided in front of the furnace body 12 (left side in FIG. 1) and a roll 18 provided in the rear of the furnace body 12 (right side in FIG. 1). The drying furnace 10 is configured as a roll-to-roll type drying furnace in which a sheet 80 having a coating film 82 formed on its upper surface is continuously conveyed by

rolls

17 and 18 and dried.

The furnace body 12 is for drying the coating film 82. The furnace body 12 is a heat insulating structure formed in a substantially rectangular parallelepiped, and is formed in the space 12a that is an internal space, and the front end face 13 and the rear end face 14 of the furnace body, and openings that serve as entrances to the space 12a from the outside. 15 and 16. The furnace body 12 has a length from the front end face 13 to the rear end face 14 of, for example, 2 to 10 m. The furnace body 12 includes a transfer passage 19 that is a passage from the opening 17 to the opening 18. The conveyance passage 19 penetrates the furnace body 12 in the horizontal direction. The sheet 80 on which the coating film 82 is applied on one side passes through the conveyance path 19.

The air supply device 20 is a device that supplies (blows) fluid to the surface side of the sheet 80 and cools the coating film 82 and the sheet 80 that pass through the furnace body 12. The air supply device 20 includes an air supply fan 21, a pipe structure 22, and an air supply port 23. The air supply fan 21 is attached to the pipe structure 22 and supplies fluid to the inside of the pipe structure 22. The fluid is cold air that can cool the sheet 80, and is, for example, room temperature or air of 50 ° C. or lower. The air supply fan 21 can adjust the flow rate and temperature of the fluid. The pipe structure 22 serves as a fluid passage from the air supply fan 21. The pipe structure 22 forms a passage from the air supply fan 21 through the ceiling of the furnace body 12 to the inside of the furnace body 12. The air supply port 23 serves as a supply port of the fluid from the air supply fan 21 to the furnace body 12. The air supply port 23 is provided at an end of the furnace body 12 on the opening 16 side that is the carry-out side of the sheet 80, and opens horizontally toward the opening 15 side that is the carry-in side. Thereby, the air supply device 20 supplies the fluid in the direction opposite to the conveying direction of the sheet 80 (in the left direction in FIG. 1).

The exhaust device 25 is a device that discharges the atmospheric gas in the furnace body 12. The exhaust device 25 includes an exhaust fan 26, a pipe structure 27, and an exhaust port 28. The exhaust port 28 is provided at an end of the furnace body 12 on the opening 15 side that is the carry-in side of the sheet 80, and opens horizontally toward the opening 16 side that is the carry-out side. The exhaust port 28 is attached to the pipe structure 27, and sucks in atmospheric gas in the furnace body 12 (mainly air blown from the air supply device 20 after flowing along the surface of the coating film 82). Guide into the body 27. The pipe structure 27 serves as a flow path for the atmospheric gas from the exhaust port 28 to the exhaust fan 26. The pipe structure 27 forms a passage from the exhaust port 28 through the ceiling of the furnace body 12 to the exhaust fan 26. The exhaust fan 26 is attached to the pipe structure 27 and exhausts the atmospheric gas inside the pipe structure 27.

The infrared heater 30 is a device that irradiates the coating film 82 passing through the furnace body 12 with infrared rays, and a plurality of infrared heaters 30 are attached near the ceiling of the space 12 a in the furnace body 12. In the present embodiment, a plurality of infrared heaters 30 (six in this embodiment) are arranged substantially uniformly from the front end face 13 side to the rear end face 14 side. The plurality of infrared heaters 30 have the same configuration, and are attached so that the longitudinal direction thereof and the conveying direction of the coating film 82 are orthogonal to each other. Hereinafter, the configuration of one infrared heater 30 will be described.

FIG. 2 is an AA cross-sectional view showing a cross section of the infrared heater 30 and the infrared absorbing plate 70 of FIG. The cross section shown in FIG. 2 is a surface cut so as to pass through the center line of the heater body 33. As shown in FIGS. 1 and 2, the infrared heater 30 includes a heater body 33 formed so that a tungsten filament 31 is surrounded by an inner tube 32, and an inner tube 32 provided outside the heater body 33. A first outer tube 34 formed as described above, and a second outer tube 35 provided outside the first outer tube 34 so as to surround the first outer tube 34, and at both ends thereof Is fitted with a cap 40 (FIG. 2). A space between the first outer pipe 34 and the second outer pipe 35 is a refrigerant flow path 39 through which a refrigerant (for example, air) can flow. The infrared heater 30 includes a temperature sensor 49 that detects the surface temperature of the second outer tube 35 (see FIG. 2). In the present embodiment, the temperature sensor 49 is disposed on the coating film 82 side (the lower side of FIGS. 1 and 2) of the second outer tube 35 as shown in FIG. The inner tube 32, the first outer tube 34, and the second outer tube 35 are arranged concentrically, and the filament 31 is positioned at the center of the circle.

The heater body 33 is supported at both ends by holders 45 arranged inside the cap 40. In the heater body 33, power is supplied to the filament 31 from a power supply source 50 (see FIG. 2) arranged outside the furnace body 12, and the filament 31 is heated to a predetermined temperature (eg, 1200 to 1700 ° C.). And radiates electromagnetic waves including infrared rays. The electromagnetic wave radiated by the filament 31 is not particularly limited. For example, the peak wavelength is in the infrared region (the wavelength is 0.7 μm to 8 μm) or the near infrared region (the wavelength is 0.7 μm to 3.5 μm). ). In this embodiment, an electromagnetic wave having a peak wavelength of around 3.5 μm is emitted. The inner tube 32 is a tube having a circular cross section surrounding the filament 31, and is formed of an infrared transmitting material that absorbs part of the electromagnetic waves radiated from the filament 31 and transmits infrared rays. Examples of such an infrared transmitting material used for the inner tube 32 include germanium, silicon, sapphire, calcium fluoride, barium fluoride, zinc selenide, zinc sulfide, chalcogenide glass, transparent alumina ceramics, and infrared rays. Examples include transmissive quartz glass. In the present embodiment, the inner tube 32 is formed of quartz glass that absorbs infrared light having a wavelength exceeding 4 μm and transmits infrared light having a wavelength of 4 μm or less as a part of the electromagnetic wave among the above-described infrared transmitting materials. It was. Further, the inside of the inner tube 32 is in a vacuum atmosphere or a halogen atmosphere. The electric wiring 31 a connected to the filament 31 is drawn out to the outside airtightly through a wiring drawing portion 47 provided in the cap 40, and is connected to the power supply source 50. As shown in FIG. 2, the cap 40 is formed by integrally molding a disc-shaped lid 44 and cylindrical portions 42 and 43 erected on the lid 44. The left and right ends of the first outer tube 34 and the second outer tube 35 are fixed to cylindrical portions 42 and 43, respectively.

The first outer tube 34 and the second outer tube 35 are tubes formed of the above-described infrared transmitting material. In the present embodiment, like the inner tube 32, the first outer tube 34 and the second outer tube 35 are formed of a quartz glass material that absorbs infrared light having a wavelength exceeding 4 μm and transmits infrared light having a wavelength of 4 μm or less. It was supposed to be. Note that the first outer tube 34 and the second outer tube 35 can be cooled to, for example, 200 ° C. or less by the refrigerant flowing through the refrigerant flow path 39.

A reflective layer 36 is formed on the outer peripheral surface of the first outer tube 34. The reflection layer 36 is formed in a region on the outer peripheral surface of the first outer tube 34 that includes the side opposite to the coating film 82 (upper side in FIG. 1) when viewed from the filament 31, and only a part of the periphery of the filament 31 is formed. It is provided to cover. In the present embodiment, the reflective layer 36 covers the entire upper half of the first outer tube 34. The reflective layer 36 is arranged so that the filament 31 is positioned at the center position of a circle including the arc of the cross section. The reflection layer 36 is formed of an infrared reflecting material that reflects at least a part of infrared rays of the electromagnetic waves radiated from the filament 31. Examples of the infrared reflecting material include gold, platinum, and aluminum. In the present embodiment, the reflective layer 36 is formed of a material that reflects at least part of infrared rays having a wavelength of 2 μm to 4 μm. The reflective layer 36 is formed by depositing an infrared reflective material on the surface of the first outer tube 34 using a film deposition method such as coating, drying, sputtering, CVD, or thermal spraying. The reflective layer 36 faces the refrigerant flow path 39 and is cooled by the refrigerant flowing through the refrigerant flow path 39.

A selective reflection layer 37 is formed on the outer peripheral surface of the second outer tube 35. The selective reflection layer 37 is disposed between the filament 31 and the coating film 82 in the space 12 a of the furnace body 12. More specifically, the selective reflection layer 37 is formed on the outer peripheral surface of the second outer tube 35 in a region including the same side as the coating film 82 (lower side in FIG. 1) as viewed from the filament 31. It is provided so as to cover only a part of the periphery. In the present embodiment, the selective reflection layer 37 covers the entire lower half of the outer peripheral surface of the second outer tube 35. The selective reflection layer 37 is arranged so that the filament 31 is located at the center position of a circle including the arc of the cross section. The selective reflection layer 37 is formed of a selective reflection material that reflects at least part of infrared rays having a wavelength of less than 2 μm and transmits at least part of infrared rays having a wavelength of 2 μm to 4 μm among electromagnetic waves radiated from the filament 31. . Thereby, the selective reflection layer 37 functions as a filter that selectively transmits infrared rays having a wavelength of 2 μm to 4 μm. The selective reflection layer 37 preferably has a higher transmittance of infrared light having a wavelength of 2 to 4 μm than that of infrared light having a wavelength of less than 2 μm. In the present embodiment, the selective reflection layer 37 has a total transmittance of infrared light having a wavelength of less than 2 μm of 20% or less, and a total transmittance of infrared light having a wavelength of 2 to 4 μm of 80% or more. The selective reflection layer 37 may transmit electromagnetic waves having a wavelength exceeding 4 μm or may reflect electromagnetic waves having a wavelength exceeding 4 μm. In the former case, the selective reflection layer 37 functions as a low-pass filter, and in the latter case, the selective reflection layer 37 functions as a band-pass filter. In the present embodiment, the selective reflection layer 37 transmits electromagnetic waves having a wavelength exceeding 4 μm. In this way, the selective reflection layer 37 that can reflect electromagnetic waves in a specific wavelength region is selectively reflected by using a film forming method in which, for example, a coating film containing a cholesteric liquid crystal material is applied to the surface of the second outer tube 35 and dried and cured. The material can be formed by film formation. Alternatively, the selective reflection layer 37 may be formed by coating a cholesteric liquid crystal film layer by layer and forming a selective reflection material including a plurality of cholesteric liquid crystal layers. The formation of such a selective reflection material is described in, for example, Japanese Patent Application Laid-Open No. 2012-181359.

The refrigerant channel 39 is a space between the first outer tube 34 and the second outer tube 35, and allows refrigerant to flow through a fluid inlet / outlet 48 provided in the cap 40. The refrigerant is a fluid such as air. The fluid inlet / outlet port 48 is connected to a first refrigerant supply source 60 disposed outside the furnace body 12. The refrigerant supplied from the first refrigerant supply source 60 flows into the refrigerant channel 39 from one fluid inlet / outlet 48, flows through the refrigerant channel 39, and flows out from the other fluid inlet / outlet 48. The refrigerant flowing through the refrigerant flow path 39 plays a role of reducing the temperature of the second outer pipe 35 and the temperature of the first outer pipe 34 which are the outer surfaces of the infrared heater 30 or adjusting the temperature to an arbitrary temperature.

The infrared absorbing plate 70 is a substantially rectangular parallelepiped member that mainly absorbs infrared rays radiated from the infrared heater 30, and a plurality of infrared absorbing plates 70 are attached between the ceiling of the space 12 a in the furnace body 12 and the infrared heater 30. In the present embodiment, six infrared absorbing plates 70 are arranged, and each infrared absorbing plate 70 corresponds to the infrared heater 30 on a one-to-one basis, and between the corresponding infrared heater 30 and the ceiling of the furnace body 12. It is attached. That is, the infrared absorbing plate 70 is disposed in the space 12 a of the furnace body 12 on the side opposite to the selective reflection layer 37 (upper side in FIGS. 1 and 2) when viewed from the filament 31 of the infrared heater 30. The plurality of infrared absorbing plates 70 have the same configuration, and are attached so that the longitudinal direction is orthogonal to the conveying direction. Hereinafter, the configuration of one infrared absorption plate 70 will be described.

As shown in FIG. 1, the infrared absorbing plate 70 is formed such that the width in the front-rear direction (the left and right widths in FIG. 1) is larger than the outer diameter of the infrared heater 30. Further, the infrared absorbing plate 70 is disposed so as to cover a region opposite to the coating film 82 of the infrared heater 30 (a region immediately above the infrared heater 30 in FIGS. 1 and 2). The infrared absorbing plate 70 is formed of an infrared absorbing material capable of absorbing at least a part of infrared rays having a wavelength of less than 2 μm. Examples of such an infrared absorbing material used for the infrared absorbing plate 70 include a Si—SiC composite material (silicon-impregnated SiC) obtained by impregnating a porous body containing SiC with molten Si. The infrared absorption plate 70 is hollow inside, and the space inside this is a refrigerant flow path 79. In the refrigerant flow path 79, the refrigerant can flow through two fluid inlets / outlets 78 provided in the infrared absorption plate 70. The refrigerant may be a fluid, for example, a gas such as air or a liquid such as water. In the present embodiment, the refrigerant is water. The fluid inlet / outlet port 78 is connected to a second refrigerant supply source 65 disposed outside the furnace body 12. The refrigerant supplied from the second refrigerant supply source 65 flows into the refrigerant channel 79 from one fluid inlet / outlet 78, flows through the refrigerant channel 79, and flows out from the other fluid inlet / outlet 78. The refrigerant flowing through the refrigerant flow path 79 serves to lower the temperature of the infrared absorbing plate 70 that is heated by absorbing infrared rays. The infrared absorption plate 70 can be cooled to, for example, 200 ° C. or less by the refrigerant flowing through the refrigerant flow path 79.

The sheet 80 is not particularly limited, but is a resin sheet, for example, and in this embodiment is made of a PET film. The sheet 80 is not particularly limited, but has a thickness of 10 to 100 μm and a width of 200 to 1000 mm, for example. The coating film 82 is applied to the upper surface of the sheet 80 and is used as a thin film for MLCC (multilayer ceramic capacitor) after drying, for example. The coating film 82 includes, for example, ceramic powder or metal powder, an organic binder, and an organic solvent. The thickness of the coating film 82 is not particularly limited, but is, for example, 20 to 1000 μm.

The controller 90 is configured as a microprocessor centered on a CPU. The controller 90 outputs a control signal to the air supply fan 21 and the exhaust fan 26 to control the temperature and air volume of the fluid blown from the air supply port 23, and exhaust from the exhaust port 28 in the atmosphere of the space 12 a. Control the amount. Further, the controller 90 inputs the temperature of the second outer pipe 35 detected by the temperature sensor 49 that is a thermocouple, or opens and closes provided in the middle of the pipe connecting the first refrigerant supply source 60 and the fluid inlet / outlet port 48. A control signal is output to the valve 61 and the flow rate adjusting valve 62 to individually control the flow rate of the refrigerant flowing through the refrigerant flow path 39 of the infrared heater 30 (see FIG. 2). Similarly, the controller 90 outputs a control signal to the on-off valve 66 and the flow rate adjustment valve 67 provided in the middle of the pipe connecting the second refrigerant supply source 65 and the fluid inlet / outlet 78, and the infrared absorbing plate 70. The flow rate of the refrigerant flowing through the refrigerant flow path 79 is individually controlled. Furthermore, the controller 90 outputs a control signal for adjusting the magnitude of the power supplied from the power supply source 50 to the filament 31 to the power supply source 50 to individually control the filament temperature of the infrared heater 30. Further, the controller 90 can adjust the passing time of the sheet 80 and the coating film 82 in the furnace body 12 and the tension applied to the sheet 80 and the coating film 82 by controlling the rotation speed of the

rolls

17 and 18. .

Next, how the coating film 82 is dried using the drying furnace 10 thus configured will be described. First, the controller 90 rotates the

rolls

17 and 18 and starts conveying the sheet 80. As a result, the sheet 80 is unwound from the roll 17 disposed at the left end of the drying furnace 10. The sheet 80 is coated with a coating film 82 on the upper surface by a coater (not shown) immediately before being brought into the furnace body 12 from the opening 15. And the sheet | seat 80 with which the coating film 82 was apply | coated is conveyed in the furnace body 12. FIG. At this time, the controller 90 controls the air supply fan 21, the exhaust fan 26, the power supply source 50, the first refrigerant supply source 60, and the second refrigerant supply source 65. Thereby, while the sheet 80 passes through the space 12 a of the furnace body 12, the coating film 82 formed on the upper surface of the sheet 80 is dried by being irradiated with infrared rays from the infrared heater 30. At the same time, the cool air from the air supply device 20 cools the coating film 82 and the sheet 80 and removes the solvent evaporated from the coating film 82. Note that the controller 90 determines the temperature and flow rate of the air supply fan 21 so that the temperature of the sheet 80 becomes a predetermined value (for example, 60 ° C., 50 ° C., 45 ° C., etc.) below the glass transition point (about 70 ° C.) of the PET film. To control. The flow rate and temperature may be determined in advance. Alternatively, for example, the temperature and the flow rate may be adjusted so that the temperature of the sheet 80 is kept below the glass transition point based on the temperature detected by a temperature sensor provided on the sheet 80 or in the furnace body 12. In this way, the coating film 82 is dried to form a thin film while the sheet 80 is kept below the glass transition point, and is transported from the opening 16. And this thin film (coating film 82) is wound with the sheet | seat 80 on the roll 18 installed in the right end of the furnace body 12. FIG. Thereafter, the thin film is peeled off from the sheet 80, cut into a predetermined shape and laminated, and an MLCC is manufactured.

Here, the infrared rays emitted from the infrared heater 30 when the coating film 82 is dried will be described. FIG. 3 is an explanatory diagram illustrating an example of wavelength characteristics of infrared rays emitted from the infrared heater 30. As described above, the infrared heater 30 emits infrared light having a peak wavelength of about 3.5 μm from the filament 31 (solid line in FIG. 3). This infrared ray includes infrared rays having a wavelength of 2 to 4 μm and infrared rays having a wavelength of less than 2 μm. And since the infrared heater 30 has the inner tube | pipe 32, the 1st outer tube | pipe 34, and the 2nd outer tube | pipe 35 which were formed with the infrared rays transmissive material mentioned above, the infrared rays of a wavelength range exceeding 4 micrometers are absorbed by these. (Area A in FIG. 3). Further, since the infrared heater 30 has the selective reflection layer 37 formed of the selective reflection material described above between the filament 31 and the coating film 82, the infrared ray having a wavelength of less than 2 μm is directed toward the coating film 82 (see FIG. 1 is reflected by the selective reflection layer 37 (region B in FIG. 3). Infrared light reflected by the selective reflection layer 37 is emitted from the selective reflection layer 37 toward the filament 31 (upward in FIG. 1), and this is absorbed by the infrared absorption plate 70. As a result, the infrared rays that reach the coating film 82 and the sheet 80 from the infrared heater 30 have a small ratio of components having a wavelength exceeding 4 μm or components having a wavelength of less than 2 μm. Of the electromagnetic waves radiated from the filament 31 in the direction opposite to the coating film 82 (upward direction in FIG. 1), infrared light having a wavelength of 2 μm to 4 μm is reflected by the reflective layer 36 and radiated to the coating film 82 side. Infrared rays that reach the coating film 82 and the sheet 80 from the infrared heater 30 have a higher proportion of components having a wavelength of 2 μm to 4 μm.

Here, the correspondence between the components of the present embodiment and the components of the present invention will be clarified. The furnace body 12 of this embodiment corresponds to the furnace body of the present invention, the filament 31 corresponds to a heating element, the infrared heater 30 corresponds to an infrared heater, the selective reflection layer 37 corresponds to a selective reflector, and absorbs infrared rays. The plate 70 corresponds to an infrared absorber. The second outer tube 35 corresponds to the tubular member and the second tube, the first outer tube 34 corresponds to the first tube, and the refrigerant channel 79 corresponds to the refrigerant channel. The coating film 82 corresponds to an object to be dried.

The drying furnace 10 of the present embodiment described above is disposed in the furnace body 12 so as to be positioned between the filament 31 and the coating film 82, reflects at least part of infrared rays having a wavelength of less than 2 μm, and has a wavelength of 2 μm to A selective reflection layer 37 that transmits at least a part of infrared rays of 4 μm and a selective reflection layer 37 that is disposed on the opposite side of the selective reflection layer 37 from the filament 31 in the furnace body 12 and can absorb at least a part of infrared rays having a wavelength of less than 2 μm An infrared absorption plate 70 is provided. Therefore, infrared rays having a wavelength of less than 2 μm can be prevented from linearly reaching the coating film 82 side from the filament 31. In addition, the presence of the infrared ray absorbing plate 70 can also prevent the infrared rays after being reflected by the selective reflection layer 37 from being further reflected by the furnace body 12 and the like and reaching the coating film 82 side. Thereby, overheating of the coating film 82 can be further suppressed. In addition, when infrared rays having a wavelength of less than 2 μm reach the coating film 82 side, for example, the coating film 82 or the sheet 80 may be overheated, and the coating film 82 may be deformed to adversely affect the coating film 82. In the drying furnace 10 of this embodiment, the influence on the coating film 82 by the infrared rays with a wavelength of less than 2 μm from the infrared heater 30 can be further suppressed. Further, when the sheet 80 or the coating film 82 is overheated, for example, the amount of cold air from the air supply fan 21 required to keep the coating film 82 below a predetermined temperature or keep the sheet 80 below the glass transition point increases. However, this can also be suppressed. Thereby, the amount of energy consumption at the time of drying can be reduced more. In the drying furnace 10, the infrared rays having a wavelength of 2 μm to 4 μm emitted from the infrared heater 30 can pass through the selective reflection layer 37 and reach the coating film 82 side. Can do.

The infrared heater 30 has a second outer tube 35 that transmits at least a part of infrared rays having a wavelength of 2 μm to 4 μm and surrounds the filament 31. The second outer tube 35 has an inner peripheral surface and an outer peripheral surface. A selective reflection layer 37 is provided in a region including the side opposite to the infrared absorption plate 70 as viewed from the filament 31 among at least one of them. For this reason, the selective reflection layer 37 is not disposed in the furnace body 12 as a member different from the infrared heater 30, and the influence on the coating film 82 by infrared rays having a wavelength of less than 2 μm from the infrared heater 30 can be further suppressed. it can.

Further, the infrared heater 30 includes a first outer tube 34 that transmits at least part of infrared rays having a wavelength of 2 μm to 4 μm and surrounds the filament 31, and a second outer tube 35 that surrounds the filament 31 and the first outer tube 34. The first outer tube 34 transmits at least a part of infrared rays having a wavelength of 2 μm to 4 μm in a region including at least one of the inner peripheral surface and the outer peripheral surface including the side opposite to the coating film 82 when viewed from the filament 31. It has a reflective layer 36 that reflects. For this reason, infrared rays having a wavelength of 2 μm to 4 μm can be reflected among electromagnetic waves radiated from the filament 31 in the direction opposite to the coating film 82. Thereby, the infrared rays of this wavelength can be efficiently irradiated onto the coating film 82 to improve the drying efficiency.

Furthermore, the infrared absorbing plate 70 has a refrigerant flow path 79 through which a refrigerant can flow. For this reason, the infrared ray absorbing plate 70 can be cooled with the refrigerant, and the infrared ray absorbing plate 70 can be further suppressed from absorbing infrared rays and overheating. Thereby, it can suppress more that the overheating of the infrared rays absorption plate 70 exerts a bad influence on the coating film 82. FIG.

It should be noted that the present invention is not limited to the above-described embodiment, and it goes without saying that the present invention can be implemented in various modes as long as it belongs to the technical scope of the present invention.

For example, in the above-described embodiment, the selective reflection layer 37 is formed on the second outer tube 35 of the infrared heater 30. However, the present invention is not limited to this, and is positioned between the filament 31 and the coating film 82 in the furnace body 12. The selective reflection layer 37 may be disposed as described above. FIG. 4 is a longitudinal sectional view of a modified drying furnace 110. The drying apparatus 110 is different from the infrared heater 30 in that the infrared heater 130 does not include the selective reflection layer 37, includes the partition 185 and the selective reflection layer 137, and includes the infrared absorption layer 170 instead of the infrared absorption plate 70. Other than these, the configuration is the same as that of the drying furnace 10. Therefore, the same components as those in the drying furnace 10 among the components in the drying furnace 110 are denoted by the same reference numerals as those in the drying furnace 10 and the description thereof is omitted. As shown in FIG. 4, the partition wall 185 is provided inside the furnace body 12. Of the space 12 a of the furnace body 12, a space in which the infrared heater 30 is provided and a space in which the coating film 82 is disposed (conveyed) It is a member which partitions off horizontally. The partition wall 185 transmits at least part of infrared rays having a wavelength of 2 μm to 4 μm, and is formed of the above-described infrared transmitting material such as quartz glass similar to the inner tube 32 or the like. A selective reflection layer 137 is formed on the surface of the partition wall 85 on the infrared heater 30 side (upper surface in FIG. 4). The selective reflection layer 137 is formed of the same selective reflection material as the selective reflection layer 37 described above. The infrared absorption layer 170 is disposed on the inner peripheral surface of the furnace body 12 on the surface opposite to the selective reflection layer 137 (upper side in FIG. 4) when viewed from the filament 31. This infrared absorption layer 170 is formed by applying and drying a material capable of absorbing at least part of infrared rays having a wavelength of less than 2 μm, such as black body paint, on the inner peripheral surface of the furnace body 12. In this drying furnace 110 as well, the selective reflection layer 137 can prevent infrared rays having a wavelength of less than 2 μm from reaching the coating film 82 side from the filament 31 as in the above-described embodiment. Further, the infrared ray absorbing layer 170 can also suppress the infrared ray after being reflected by the selective reflection layer 137 from being further reflected by the furnace body 12 or the like. Moreover, since the space in which the infrared heater 30 is disposed and the space in which the coating film 82 is disposed are partitioned by the partition 185, the space in which the infrared heater 30 is disposed, the object in the space, and the space are faced. Even when the furnace body 12 or the like is heated by infrared rays having a wavelength of less than 2 μm, the coating film 82 and the sheet 80 are not easily heated. Therefore, the influence on the coating film 82 by the infrared rays having a wavelength of less than 2 μm from the infrared heater 30 can be further suppressed. Further, since the infrared absorption layer 170 is formed on the inner peripheral surface of the furnace body 12, it is reflected by the selective reflection layer 137 without disposing an independent member such as the infrared absorption plate 70 in the furnace body 12. Infrared light can be absorbed by an infrared absorber. Unlike the infrared absorption plate 70, the infrared absorption layer 170 does not have a coolant channel, but it is not always necessary to cool the infrared absorption layer 170. This is because the space is partitioned by the partition 185, and even if the infrared absorption layer 170 itself is overheated, there is little influence on the space on the coating film 82 side. In the drying furnace 110 of FIG. 4, the infrared heater 130 may include the selective reflection layer 37 similarly to the infrared heater 30, and the infrared absorption plate 70 may be disposed in the furnace body 12.

In the above-described embodiment, the selective reflection layer 37 is formed on the outer peripheral surface of the second outer tube 35, but may be formed on the inner peripheral surface. In addition, the selective reflection layer 37 is formed by directly forming a selective reflection material on the surface of the second outer tube 35, but is not limited thereto. For example, a selective reflection film manufactured by forming a selective reflection material on a resin film as a substrate may be prepared and bonded to the surface of the second outer tube 35. In this case, it is preferable that the substrate of the selective reflection film transmits at least part of infrared rays having a wavelength of 2 μm to 4 μm. In the drying furnace 110 of FIG. 3 described above, a selective reflection film may be used instead of the selective reflection layer 137 in the same manner. Or you may arrange | position the independent member which consists of selective reflection materials instead of the selective reflection layers 37 and 137 so that it may be located in the furnace body 12 between the filament 31 and the coating film 82. FIG.

In the above-described embodiment, the reflective layer 36 is formed on the outer peripheral surface of the first outer tube 34, but may be formed on the inner peripheral surface. The reflective layer 36 may not be provided.

In the above-described embodiment, one infrared absorbing plate 70 is disposed for each infrared heater 30, but the present invention is not limited to this. For example, one infrared absorption plate 70 may be disposed so as to cover the side opposite to the selective reflection layer 37 among the plurality of infrared heaters 30. Further, the drying furnace 10 may include the infrared absorption layer 170 of the drying furnace 110 instead of the infrared absorption plate 70.

In the above-described embodiment, the inner tube 32, the first outer tube 34, and the second outer tube 35 are made of quartz glass that absorbs infrared light having a wavelength exceeding 4 μm and transmits infrared light having a wavelength of 4 μm or less. Any infrared ray having a wavelength of 2 μm to 4 μm can be used. For example, one or more of the inner tube 32, the first outer tube 34, and the second outer tube 35 may absorb infrared light having a wavelength exceeding 3.5 μm and transmit infrared light having a wavelength of 3.5 μm or less. Good. Similarly, the selective reflection layer 37 transmits at least part of infrared rays having a wavelength of 2 μm to 4 μm. However, the selective reflection layer 37 may transmit at least part of infrared rays having a wavelength of 2 μm to 3.5 μm. Infrared rays having a wavelength of 3.5 μm or less are excellent in the ability to cut hydrogen bonds in molecules such as water and solvents, so that the inner tube 32, the first outer tube 34, the second outer tube 35, and the selective reflection layer 37 are formed. By passing through this, the coating film 82 can be dried more efficiently.

In the embodiment described above, the filament 31 emits an electromagnetic wave having a peak wavelength in the vicinity of 3.5 μm. However, the present invention is not limited to the case where the peak wavelength is in the region of 2 μm to 4 μm. It may be in the excess area. Even in this case, the inner tube 32, the first outer tube 34, the second outer tube 35, and the selective reflection layer 37 suppress the arrival of infrared rays having a wavelength of less than 2 μm or infrared rays having a wavelength of more than 4 μm. That is, even when the peak wavelength of the electromagnetic wave emitted by the filament 31 is not in the region of 2 μm to 4 μm, the inner tube 32, the first outer tube 34, the second outer tube 35, and the selective reflection layer 37 reach the coating film 82. The peak wavelength of the electromagnetic wave can be set to 2 μm to 4 μm. However, in order to further improve the drying efficiency, it is preferable that the peak wavelength of the electromagnetic wave emitted from the filament 31 is in the region of 2 μm to 4 μm.

In the embodiment described above, the coating film 82 is used as a thin film for MLCC, but is not limited thereto. For example, it may be used as a thin film for LTCC (low temperature fired ceramics) or other green sheets. Or the coating film 82 is good also as what is used as a coating film used as an electrode for batteries, such as a lithium ion secondary battery. In this case, for example, the coating film 82 may be obtained by applying an electrode material paste obtained by kneading together an electrode material (positive electrode active material or negative electrode active material), a binder, a conductive material, and a solvent onto the sheet 80. When the coating film 82 is a coating film that serves as an electrode for a battery, the sheet 80 may be a metal sheet such as aluminum or copper. Further, the temperature of the air blown from the air supply fan 21 may be appropriately changed according to the material of the coating film 82 and the sheet 80, and may be blown in the range of 40 to 400 ° C., for example.

This application is based on Japanese Patent Application No. 2013-083032 filed on April 11, 2013, and the contents of all of the contents are included in this specification by reference.

The present invention can be used in industries that require drying of an object to be dried, such as a coating film, for example, a ceramic industry that manufactures MLCC, LTCC, and the like, a battery industry that manufactures an electrode coating film of a lithium ion secondary battery, and the like.

10, 110 Drying furnace, 12 furnace body, 12a space, 13 front end face, 14 rear end face, 15, 16 opening, 17, 18 roll, 19 transport passage, 20 air supply device, 21 air supply fan, 22 pipe structure, 23 air supply port, 25 exhaust device, 26 exhaust fan, 27 pipe structure, 28 exhaust port, 30, 130 infrared heater, 31 filament, 31a electrical wiring, 32 inner tube, 33 heater body, 34 first outer tube, 35 Second outer tube, 36 reflective layer, 37, 137 selective reflective layer, 39 refrigerant flow path, 40 cap, 42-43 cylindrical part, 44 lid, 45 holder, 47 wiring outlet, 48 fluid inlet / outlet, 49 temperature sensor, 50 Power supply source, 60 first refrigerant supply source, 61 on-off valve, 62 flow rate adjustment valve, 65 second refrigerant supply source, 6-off valve, 67 flow control valve, 70 an infrared absorbing plate, 78 a fluid inlet and outlet, 79 a refrigerant flow passage, 80 sheets, 82 coating film, 90 controller, 170 an infrared absorbing layer, 185 bulkhead.

Claims

A furnace body for drying the object to be dried;
An infrared heater having a heating element that is disposed in the furnace and emits electromagnetic waves including infrared;
Selective reflection that is disposed in the furnace so as to be positioned between the heating element and the object to be dried, reflects at least part of infrared rays having a wavelength of less than 2 μm, and transmits at least part of infrared rays having a wavelength of 2 μm to 4 μm. Body,
An infrared absorber disposed on the opposite side to the selective reflector as viewed from the heating element in the furnace, and capable of absorbing at least part of infrared rays having a wavelength of less than 2 μm;
Drying oven equipped with.
The infrared heater includes a tubular member that transmits at least part of infrared rays having a wavelength of 2 μm to 4 μm and surrounds the heating element;
The tubular member has the selective reflector in a region including at least one of an inner peripheral surface and an outer peripheral surface including a side opposite to the infrared absorber when viewed from the heating element.
The drying furnace according to claim 1.
The infrared heater includes a first tube that transmits at least part of infrared rays having a wavelength of 2 μm to 4 μm and surrounds the heating element, and a second tube that is the tubular member surrounding the heating element and the first tube. And
The first tube is a reflective layer that reflects at least a part of infrared light having a wavelength of 2 μm to 4 μm in a region including at least one of an inner peripheral surface and an outer peripheral surface including a side opposite to the object to be dried when viewed from the heating element. have,
The drying furnace according to claim 2.
A partition partitioning a space in which the infrared heater is disposed and a space in which the drying target is disposed in the furnace, and transmitting at least part of infrared rays having a wavelength of 2 μm to 4 μm;
With
The partition has the selective reflector,
The drying furnace according to any one of claims 1 to 3.
The furnace body has the infrared absorber on the inner peripheral surface,
The drying furnace according to claim 4.
The infrared absorber has a refrigerant flow path through which a refrigerant can flow.
The drying furnace according to any one of claims 1 to 5.