Heating device for sheet with coating film

Abstract

To provide a heating device that can prevent the overheating of both ends not coated with a coating film in the width direction of the sheet, and can uniformly heat the coating film, upon heating a coating film coated on a sheet in a production process of a sheet coated with a coating film.SOLUTION: The present invention relates to a heating device radiating radiant light toward a coating liquid coated on a sheet coated with the coating liquid in transfer, except on either end or both ends in the width direction thereof. The heating device is provided with a first heating source that irradiates a region including a boundary between a segment applied with the coating liquid and a segment not applied with the coating liquid, with radiant light, a second heating source that exclusively irradiates a segment applied with the coating liquid, with radiant light, and a shielding plate disposed between the sheet and the first heating source to cover the segment of the sheet not applied with the coating liquid. The first heating source is, or the first heating source and the second heating source are, provided with a reflective material of a convexly curved shape when observed from the sheet transfer direction.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a heating device for a sheet with a coating film.

Background Art

[0002] As a device for drying a coating liquid applied to a sheet, a simple hot air nozzle is generally used. In some cases, an infrared heater with a reflector having an integrated structure is also used as a means for promoting the heating of the coating liquid. Patent Document 1 discloses a heating device in which hot air nozzles and hot air outlets are alternately arranged in the sheet conveyance direction, and an infrared heater is installed at the hot air outlet, as a heating device for efficiently drying a coating liquid. This quickly raises the temperature of the sheet and the coating liquid by the radiant heat of the infrared heater, blows hot air from the hot air nozzle onto the sheet, peels off the evaporation layer near the surface of the sheet, and exhausts it to the outside. By quickly heating the sheet and keeping the vapor concentration near the coating liquid low, the coating liquid can be quickly dried.

[0003] The case where the heating device disclosed in this Patent Document 1 is applied to a sheet production device such as a resin film will be described. FIG. 10 is a schematic view of applying a heating device to a resin film production device, which includes an extruder 7, a die 8, a cooling drum 9, a longitudinal stretching machine 10, a coating liquid application device 11, a heating device 12(22), a transverse stretching machine 13, and a winding device 14. First, a polymer is extruded by the extruder 7, and the molten polymer is formed into a sheet shape through the die 8 and the cooling drum 9. Thereafter, the sheet is stretched in the conveyance direction by the longitudinal stretching machine 10, and the coating liquid is applied to one or both sides of the sheet by the coating liquid application device 11. After drying the coating liquid with the heating device 12(22), the sheet is stretched in the width direction by the transverse stretching machine 13 and continuously wound by the winding device 14. The stretching method in the transverse stretching machine 13 is to stretch the sheet in the width direction by gripping both end portions in the width direction of the sheet with a gripping mechanism called a clip.

[0004] In this way, the sheet is stretched in a certain direction during its manufacturing process, aligning the molecules in the deformation direction and increasing the strength. However, both ends in the width direction of the sheet after transverse stretching cannot be used as products because gripping marks such as those made by clips are left. Therefore, both ends in the width direction of the sheet with gripping marks are cut at the outlet of the transverse stretching machine 13. Both ends in the width direction of the cut sheet are recovered, melted, and reused as polymers. At this time, if a coating liquid is applied to the recovered sheet, it will become an impurity when melted. Therefore, in the coating liquid application device 11, both ends in the width direction of the sheet are uncoated parts and the coating liquid is not applied.

[0005] Here, when the coating liquid is dried by the heating device 12(22), the uncoated parts at both ends in the width direction of the sheet tend to become high in temperature because heat is not consumed by the latent heat of vaporization of the coating liquid like in the coated parts. Therefore, problems such as the uncoated parts at both ends in the width direction of the sheet being thermally deformed and unable to be gripped by the gripping mechanism at the inlet of the subsequent transverse stretching machine 13 occur. Alternatively, problems such as stretching defects where only the high-temperature uncoated parts are selectively stretched during stretching and the thickness becomes uneven, the coated parts that become products are not stretched by the required amount and the strength of the product sheet is insufficient, or the sheet is torn based on the uncoated parts also exist. Especially, the thicker the coating liquid thickness of the coated part, the greater the amount of heat that must be applied until drying is completed, so the uncoated parts are in a more overheated state. Therefore, it is necessary to prevent overheating of the uncoated parts. As a countermeasure, a method of installing a shielding member between the infrared heater and the hot air nozzle and the sheet at both ends in the width direction of the sheet can be mentioned. In this case, since the radiant heat from the infrared heater is the main heat source rather than the hot air nozzle, it is important to shield the infrared rays. As a technique for shielding infrared rays, Patent Document 2 discloses a technique of using a porous shielding plate to reduce the radiant light incident on both ends in the width direction of the sheet. Also, Patent Document 3 discloses a technique of using a shielding member inclined away from the sheet as it goes from near the boundary between the coated part and the uncoated part toward both ends in the width direction of the sheet to reduce the radiant light incident on the uncoated parts at both ends in the width direction of the sheet.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0007] As a result of detailed examination of an infrared heater in which a reflector has an integral structure and is used in combination as a means for promoting heating of a coating liquid, the inventors have grasped that the radiation state from the heater is as shown in FIG. 8a. This is because when irradiating the radiation light from the heater toward the sheet and the coating liquid, the radiation light going toward the side opposite to the sheet and the coating liquid is reflected by the reflector and irradiated toward the sheet and the coating liquid, while it has been found that the reflection by the reflector spreads in a diffused state. In this state, when shielding the radiation light with a shielding member, depending on the positional relationship between the film and the infrared heater, the radiation light may enter the uncoated portion that needs to be shielded, and the uncoated portion may have its temperature rise (FIG. 8b). In the technology of Patent Document 2, in order to suppress uneven heating, it is necessary to bring the shielding member close to the film. However, since the shielding member that is constantly irradiated with the radiation light becomes very hot, when the shielding member is used close to the film, the uncoated portions at both ends in the width direction of the film are heated by the radiant heat and heat transfer emitted from the shielding member (FIG. 8c). Also, during conveyance of the sheet, when fluttering occurs in the vertical direction perpendicular to the conveyance direction, the shielding member may come into contact with the sheet, and the sheet may be damaged or may lead to tearing of the sheet. Further, although a means of using a porous shielding member and cooling the shielding member by the gas flowing through the holes is disclosed, when the shielding member is brought close to the film, the gas becomes difficult to flow through the holes, and thus the cooling effect of the shielding member may not be sufficiently exhibited.

[0008] Even with the technology of Patent Document 3, since the inclined shielding member, especially its tip, is close to the sheet, there are cases where the uncoated portion is locally heated more than necessary, the shielding member contacts the sheet and causes damage, or the sheet is torn (Fig. 9).

[0009] In the production of a sheet with a coating film, the present invention provides a heating device for a sheet with a coating film that can suppress the occurrence of the above problems, reduce overheating in the uncoated portion, and irradiate the coating film with uniform radiant light when heating and drying the applied coating liquid. [Means for Solving the Problems]

[0010] [1] A heating device for a sheet with a coating film according to a first embodiment of the present invention for solving the above problems is a sheet with a coating liquid applied thereto except for one or both ends in the sheet width direction, and is a heating device for heating the coating liquid on the sheet being conveyed, a first heat source that irradiates radiant light to a region including the boundary between the portion where the coating liquid is applied and the portion where the coating liquid is not applied on the sheet, and a second heat source that irradiates radiant light only to the portion where the coating liquid is applied on the sheet, and the first heat source is in a form composed of a long shape extending in the sheet conveyance direction or a plurality of heat sources arranged in the sheet conveyance direction, and includes a reflector that reflects the radiant light toward the sheet, and the shape of the reflector observed from the sheet conveyance direction is convexly curved.

[0011] The heating device for a sheet with a coating film according to the first embodiment of the present invention is preferably any of the following aspects [2] to [4]. [2] The heating device for a sheet with a coating film according to [1] above, wherein the reflector is a parabolic reflector. [3] The heating device for a sheet with a coating film according to [1] above, wherein the reflector is a light - collecting reflector. [4] A heating device for a coated sheet according to any one of [1] to [3] above, comprising a shielding member disposed at a position closer to the sheet than the first heat source and blocking the incident radiation light directly irradiated from the first heat source and the radiation light reflected by the reflecting member to a portion of the sheet where the coating liquid is not applied.

[0012] [5] A heating device for a coated sheet according to a second embodiment of the present invention that solves the above problems is a sheet coated with a coating liquid except for one or both ends in the sheet width direction, and is a heating device for heating the coating liquid of the conveyed sheet. A first heat source that irradiates radiation light to a region including the boundary between the portion of the sheet where the coating liquid is applied and the portion where the coating liquid is not applied; A second heat source that irradiates radiation light only to the portion of the sheet where the coating liquid is applied, and the first heat source and the second heat source are respectively in a long shape extending in the sheet conveyance direction or in a form composed of a plurality of heat sources arranged in the sheet conveyance direction, and a reflecting member that reflects the radiation light toward the sheet, and the reflecting member has a convexly curved shape when observed from the sheet conveyance direction.

[0013] The heating device for a coated sheet according to the second embodiment of the present invention is preferably any one of the following [6] to [8]. [6] The heating device for a coated sheet according to [5] above, wherein the reflecting member is a parabolic reflecting member. [7] The heating device for a coated sheet according to [5] above, wherein the reflecting member is a condensing reflecting member. [8] A heating device for a coated sheet according to any one of [5] to [7] above, comprising a shielding member disposed at a position closer to the sheet than the first heat source and blocking the incident radiation light directly irradiated from the first heat source and the radiation light reflected by the reflecting member to a portion of the sheet where the coating liquid is not applied.

[0014] In the present invention, the parabolic reflector means a reflector that directs the radiant light from the heating source to suppress diffusion and intensively irradiates the radiant light onto the projected area of the reflector as viewed from the sheet side. In the present invention, the condenser reflector means a reflector that directs the radiant light from the heating source to suppress diffusion and intensively irradiates the radiant light inside the projected area of the reflector as viewed from the sheet side. In the present invention, the "running position of the sheet" means the position where the sheet runs when passing through the heating device when the sheet is actually being conveyed.

Advantages of the Invention

[0015] According to the heating device for the coated sheet of the present invention, in the production process of the continuously produced sheet, when heating the coating film applied to the sheet, only the coating liquid (coating film) applied to the sheet can be selectively heated, and the incidence of radiant light from the heating source to the uncoated portions where the coating liquid is not applied at both ends in the width direction of the sheet can be prevented. Therefore, the temperature rise of the uncoated portions can be suppressed. Further, since the radiant light from the heating source is irradiated onto the sheet surface evenly, uneven heating of the coating film can be prevented.

[0016] Also, according to the heating device for the coated sheet of the present invention, even when a shielding member is installed, the distance between the shielding member and the sheet can be increased, so that heat transfer from the high-temperature shielding member to the sheet can be prevented, and contact between the film and the shielding member can also be prevented.

Brief Description of the Drawings

[0017]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Mode for Carrying Out the Invention

[0018] Hereinafter, examples of embodiments of the present invention will be described with reference to the drawings. However, the present invention is not limited to the following forms at all.

[0019] Fig. 1(a) is a schematic plan view of the heating device 12 for a coated sheet according to the first embodiment of the present invention as viewed from the sheet side, and Fig. 1(b) is a schematic cross-sectional view as viewed from the sheet conveyance direction side.

[0020] The sheet 1 with the coating film 2 formed thereon travels in the right direction in Fig. 1(a) and in the direction perpendicular to the plane of the paper in Fig. 1(b). The coating film 2 applied in the previous process is formed on the portion of the sheet 1 excluding both ends in the width direction. The first heating source 3 is in the form of a long shape extending in the conveyance direction of the sheet 1 or a form composed of a plurality of heating sources arranged in the sheet conveyance direction, and is arranged so as to be able to irradiate the region including the boundary between the portion where the coating film 2 of the sheet 1 is applied and the non-coated portion (uncoated portion) with radiant light. It is preferable to use an infrared heater for this first heating source 3, but an optimum heater may be used in consideration of the absorption wavelength of the sheet 1 and the coating film 2, the maximum output of the heater, the lifespan, etc., and it is not limited to the infrared heater.

[0021] The reflector 5 is attached to the first heating source 3 and is used to selectively and efficiently irradiate the sheet 1 and the coating film 2 with the irradiation light from the heating source 3. This reflector 5 will be further described with reference to Figs. 5 and 6. As the reflector 5 in the present invention, it is preferable to use the parabolic reflector 51 shown in Fig. 5 and the condensing reflector 52 shown in Fig. 6.

[0022] First, with reference to Fig. 5, the parabolic reflector 51 and the radiant light irradiated from the heating source 3 will be described. The parabolic reflector 51 has a convex curved shape and is preferably shaped to direct and reflect the radiant light from the heating source 3 and irradiate the sheet 1 and the coating film 2 as shown by the arrow schematically shown in Fig. 5. In particular, in the cross-section viewed from the traveling direction of the sheet 1, it is preferable that the reflector is formed such that the width h of the parabolic reflector 51 and the width g where the radiant light is strongly irradiated are in substantially the same region. In Fig. 5, g is the range where the radiant light including the reflected light irradiated on the sheet by the heating source 3 provided with the parabolic reflector 51 is strongly irradiated, and the length h in the width direction of the parabolic reflector 51 and g are preferably in substantially the same region. Although the direct light from the heating source is omitted in Fig. 5, it is most preferable that the shape of the parabolic reflector 51 is such that most of the direct light is also irradiated within the region of g.

[0023] Next, with reference to FIG. 6, the light-concentrating reflector 52, the radiant light irradiated from the heat source 3, and the reflected light will be described. The light-concentrating reflector 52 preferably has a convex curvature similar to the parabolic reflector 51 in FIG. 5, and as shown by the arrow schematically shown in FIG. 6, by orienting the irradiated light from the heat source 3 to effectively concentrate and reflect it, it is preferably in a shape that irradiates the sheet 1 and the coating film 2. In FIG. 6, i is the range where the irradiated light including the reflected light irradiated onto the sheet by the heat source 3 provided with the light-concentrating reflector 52 is strongly irradiated. The widthwise length j of the light-concentrating reflector 52 and i preferably satisfy the relationship j ≧ i. Although the direct light is not shown in FIG. 6 as in FIG. 5, it is most preferable that the shape of the light-concentrating reflector 52 is such that the direct light is also irradiated within the region i.

[0024] The reflectors 51 and 52 shown in FIGS. 5 and 6 preferably have flow paths for flowing a fluid therein. By flowing a fluid through the reflectors 51 and 52 for cooling, it is possible to suppress excessive temperature rise and thermal deformation of the reflectors 51 and 52 during heating. The fluid to be used may be appropriately selected from air, water, oil, a dedicated coolant, etc., but it is more preferable to flow water having a high thermal conductivity and being easy to handle as the heat medium.

[0025] As the material of the reflectors 51 and 52, any of metals such as aluminum, stainless steel, iron, gold, silver, and copper, or heat-resistant resins and glass may be used. However, those having a high reflectivity of infrared rays from the heat source 3, a large thermal conductivity, a high heat-resistant temperature, and a small thermal expansion coefficient are preferable. That is, the temperature rise of the reflectors 51 and 52 due to infrared rays from the heat source 3 is suppressed, the cooling effect by a fluid such as cooling water is enhanced, charring, excessive temperature rise, and thermal deformation of the reflectors 51 and 52 are less likely to occur, and energy loss due to reflection can be reduced, which is preferable.

[0026] Also, it is preferable that the reflectors 51 and 52 have a high reflectivity with respect to the radiation light irradiated from the first heat source 3. The higher the reflectivity, the lower the heat absorption and the higher the irradiation efficiency. Therefore, the temperature rise of the reflectors 51 and 52 can be suppressed, and the energy loss during reflection can be reduced. Thus, it is preferable to coat the surfaces of the reflectors 51 and 52 irradiated with the radiation light from the first heat source 3 with a coating material, and to make the material of the coating material have a higher reflectivity with respect to the radiation light irradiated from the first heat source 3 than the materials of the reflectors 51 and 52. Even if the material with a high reflectivity is expensive, by using the material with a high reflectivity only for the coating material on the surfaces of the reflectors 51 and 52, the reflectivity can be improved at a lower cost than making the entire reflectors 51 and 52 of the material with a high reflectivity. As the specific material of the coating material, an optimal material may be selected according to the wavelength of the radiation light irradiated from the first heat source 3 and the use environment. However, a material containing gold having a high reflectivity in the near-infrared region is preferable, and a material containing 90% by mass or more of gold is more preferable.

[0027] Return to Fig. 1(b). The distance a between the sheet 1 and the first heat source 3 can be appropriately determined by the user in view of the combination of the properties of the coating liquid used and the first heat source 3, the time that can be spent on drying in the process, etc., in order to efficiently heat the coating film 2 and effectively dry it. On the other hand, when the distance between the sheet 1 and the closest part of the first heat source 3 and the reflector 5 to the sheet 1 is short, the sheet 1 may be deformed due to excessive heat reception, and there is also a concern of contact when the sheet 1 sways and flutters in the vertical direction (the vertical direction of the paper surface) during conveyance. Therefore, it is preferable to ensure a distance such that they do not come into contact with each other. Specifically, it is preferably in the range of 20 to 200 mm.

[0028] Symbol 4 is the second heat source, and it is installed with the longitudinal direction of the heat source along the sheet width direction in order to efficiently irradiate radiant light only on the portion of the sheet 1 where the coating film 2 is applied. It is preferable to use an infrared heater for this second heat source 4, but an optimal heater may be used in consideration of the absorption wavelength of the sheet 1 and the coating film 2, the maximum output of the heater, the lifespan, etc., and it is not limited to an infrared heater. Also, as long as it irradiates only the portion where the coating film 2 is formed, a heater in which the second heat source 4 and a reflector (not shown) have an integrated structure may be used.

[0029] Also, in order to efficiently heat the coating film 2, the distance b between the sheet 1 and the second heat source 4 is preferably small, but even if the sheet 1 is deformed by heat or sways and fluctuates in the vertical direction (up and down direction of the paper surface), it is preferable to ensure a distance such that they do not come into contact with each other. Specifically, it is preferably in the range of 20 to 200 mm.

[0030] Since it is preferable for this second heat source 4 to irradiate radiant light only on the portion of the sheet 1 where the coating film 2 is applied, the longitudinal length c is preferably shorter than the width direction length of the coating film 2. The diffusion state of the radiant light irradiated from the second heat source 4 depends on the relative positions of the second heat source 4, the sheet 1, and the coating film 2, and the shape of the reflector (not shown) provided on the second heat source 4, etc. Therefore, the longitudinal length c of the second heat source 4 may be suitably selected in consideration of the width direction length of the coating film 2 and the shape of the provided reflector.

[0031] The air supply mechanism 17 and the exhaust mechanism 18 in the present invention will be described in detail with reference to Fig. 1(a). The heating device 12 in Fig. 1(a) may have, in addition to the first heat source 3 and the second heat source 4, an air supply mechanism 17 that blows gas toward the sheet 1 and an exhaust mechanism 18 that exhausts the gas blown by the air supply mechanism 17.

[0032] The air supply mechanism 17 and the exhaust mechanism 18 can remove the components evaporated by heating the coating film 2, and can perform drying efficiently. It is preferable to use a nozzle made of metal for the air supply mechanism 17. Examples of the form of the nozzle include a slit nozzle, a hole nozzle, a stripe nozzle, etc. Further, by alternately arranging the air supply nozzle 17 and the exhaust port of the exhaust mechanism 18 with respect to the conveyance direction of the sheet 1, it is possible to achieve both high-efficiency heating of the coating film 2 and removal of the evaporated components.

[0033] As the gas to be supplied, it is preferable to use air, but steam or an inert gas etc. may be used when used in an explosion-proof facility etc. Also, the temperature of the gas depends on the sheet 1 and the coating film 2, but is preferably 30 to 150 °C, more preferably 60 to 120 °C. When the temperature of the gas to be sprayed is within these ranges, it is preferable because the drying efficiency becomes higher.

[0034] A more preferable form of the heating device 12 will be described with reference to Fig. 2(b). The shielding member 6 in Fig. 2(b) is disposed between the sheet 1 and the first heating source 3 to shield the radiation light (the radiation light directly irradiated from the first heating source 3 and the radiation light reflected by the reflector 5) from entering the uncoated portions formed at both ends in the width direction of the sheet 1 where the coating film 2 is not formed. The case where the shielding member 6 is disposed using a parabolic reflector 51 or a condensing reflector 52 for the reflector 5 will be described with reference to Fig. 7.

[0035] Fig. 7(a) schematically shows the irradiation of radiant light including reflected light when the first heat source 3 is combined with the parabolic reflector 51 and the shielding member 6 is disposed near the uncoated portion of the sheet 1. Similarly, Fig. 7(b) schematically shows the irradiation of radiant light including reflected light when the first heat source 3 is combined with the condenser reflector 52 and the shielding member 6 is disposed near the uncoated portion of the sheet 1. In both Fig. 7(a) and Fig. 7(b), since the radiant light including the reflected light is oriented, even if the shielding member 6 is disposed at a position away from the sheet 1, the incidence of the radiant light on the uncoated portion can be reduced, and the heating of the uncoated portion can be suppressed. Therefore, even if the sheet 1 is deformed by heat or shaken and fluttered in the vertical direction (the up-and-down direction of the paper surface), the distance d between the sheet 1 and the shielding member 6 can be increased, so that the contact between the sheet 1 and the shielding member 6 can be prevented. Further, since the distance d between the sheet 1 and the shielding member 6 can be increased, the influence of the radiant heat emitted from the shielding member and the heating of the uncoated portions at both ends in the width direction of the sheet 1 due to heat transfer can be reduced. From the above, the distance d between the sheet 1 and the shielding member 6 may be appropriately determined by the user in view of the shape of the heat source and the reflector to be applied, but it is preferably arranged preferably in the range of 20 to 80 mm.

[0036] Also, the arrangement position of the shielding member 6 in the width direction of the sheet 1 also varies depending on the uncoated portion area where the coating film 2 is not formed on the sheet 1 and the state of the radiant light to be shielded. For example, in the state of radiant light shown in FIG. 7(a), when observed from a direction perpendicular to the surface of the sheet 1, the shielding member 6 is arranged so as to cover the uncoated portion area including the boundary between the coated portion area where the coating film 2 is formed and the uncoated portion area where it is not formed. In this case, it is not necessary to cover the entire uncoated portion area with the shielding member 6, and it is not necessary to cover the range where the radiant light is not irradiated with the shielding member 6. On the other hand, in the state of radiant light shown in FIG. 7(b), even if the shielding member 6 is arranged at a position that does not cover the boundary between the coated portion area and the uncoated portion area when observed from a direction perpendicular to the surface of the sheet 1, the uncoated portion area can be prevented from being irradiated with the radiant light. Thus, the arrangement position of the shielding member 6 can be appropriately adjusted by the user, and it is preferable to adjust while observing the drying state near the widthwise end of the coating film 2 and the heating state of the uncoated portion area of the sheet 1 where the coating film 2 is not formed. Therefore, it is preferable that the shielding member 6 can be adjusted in position in the width direction with respect to the sheet 1 and also in the direction perpendicular to the sheet 1 by a feed screw mechanism (not shown) or the like.

[0037] The shielding member 6 used in the present invention is preferably a plate-like body, and its thickness may be appropriately selected and installed according to the material used and the distance between the first heating source 3, the sheet 1, and the coating film 2. However, since it leads to cost reduction and downsizing of the members and the device, it is preferably a thin member. Although it depends on the material used, the thickness of the plate-like body is preferably between 0.5 and 10 mm, and the user can appropriately select and use it.

[0038] Also, the shielding member 6 exposed to a high-temperature heating source may have a flow path for flowing a fluid inside. That is, by flowing a fluid through the shielding member 6 to cool it, the heat transferred from the shielding member 6 to the uncoated portion of the sheet 1 can be further reduced, and it is preferable because charring and thermal deformation of the shielding member 6 are less likely to occur. The fluid to be used may be appropriately selected from air, water, oil, a dedicated coolant, etc., but it is more preferable to flow water having a high thermal conductivity and being easy to handle as the heat medium.

[0039] As the material of the shielding member 6, any of metals such as aluminum, stainless steel, iron, gold, silver, and copper, and ceramics, glass, etc. may be used, but those having a high infrared reflectance, high thermal conductivity, high heat resistance temperature, and small thermal expansion coefficient are preferred. That is, the temperature rise of the shielding member 6 due to infrared rays is suppressed, the cooling effect by a fluid such as cooling water is enhanced, and charring, excessive temperature rise, and thermal deformation are less likely to occur.

[0040] The higher the reflectance of this shielding member 6 with respect to the irradiated radiant light, the more the heat absorption can be reduced. Therefore, it is preferable to cover only the surface of the shielding member 6 facing the heat source with a coating material, and to make the material of the coating material have a higher reflectance with respect to the radiant light irradiated from the heat source than the material of the shielding member 6. By using a material with a high reflectance only for the coating material, it is cheaper than making the shielding member 6 itself of a material with a high reflectance, and the reflectance of the shielding member 6 can be improved. Even if not all of the surface of the shielding member 6 facing the heat source is covered with the coating material, it is effective to selectively cover only the portion where the radiant light hits well, but it is more preferable to cover all of this surface with the coating material.

[0041] As the material of the specific coating material, an optimal material may be selected according to the wavelength of the radiant light irradiated from the heat source and the use environment, but a material containing gold having a high reflectance in the near-infrared region is preferred, and a material containing 90 mass% or more of gold is more preferred.

[0042] Next, the heating device 22 for the coated sheet according to the second embodiment of the present invention will be described. FIG. 3(a) is a schematic plan view of the heating device 22 for the coated sheet according to the second embodiment of the present invention as viewed from the sheet side, and FIG. 3(b) is a schematic cross-sectional view as viewed from the sheet conveyance direction. The coated sheet 1 travels in the right direction in FIG. 3(a) and in a direction orthogonal to the paper surface in FIG. 3(b). A coating film 2 applied in the previous process is formed on a portion excluding both ends in the width direction of the sheet 1. Similar to the case of FIG. 1(b), the first heating source 3 has a long shape extending in the conveyance direction of the sheet 1 or is configured by a plurality of heating sources arranged in the sheet conveyance direction, and is arranged so as to be able to irradiate radiant light onto a region including the boundary between the portion of the sheet 1 where the coating liquid 2 is applied and the portion where it is not applied (uncoated portion). It is preferable to use an infrared heater for this first heating source 3, but an optimal heater may be used in consideration of the absorption wavelength of the sheet 1 and the coating film 2, the maximum output of the heater, the lifespan, etc., and it is not limited to an infrared heater.

[0043] The reflector 5 is provided on the first heating source 3 and is used to selectively and efficiently irradiate the sheet 1 and the coating film 2 with the irradiation light from the heating source 3. This reflector 5 is as described with reference to FIGS. 5 and 6 in the first embodiment, and the description thereof will be omitted.

[0044] The distance a between the sheet 1 and the first heating source 3 in FIG. 3(b) is preferably in the range of 20 to 200 mm for the same reason as making the distance a between the sheet 1 and the first heating source 3 in the first embodiment in the range of 20 to 200 mm.

[0045] Symbol 4 is the second heating source. Similar to the first heating source 3, it has a long shape extending in the conveyance direction of the coated sheet 1, or is composed of a plurality of heating sources arranged in the sheet conveyance direction, and is preferably installed in parallel in the sheet width direction. Similar to the first heating source 3, a reflector 5 is provided and is used to selectively and efficiently irradiate the sheet 1 and the coating film 2 with the irradiation light from the second heating source 4. When the second heating source 4 and the reflector 5 are arranged in parallel, the mutual arrangement distance e in the sheet width direction of the second heating source 4 depends on the type and performance of the second heating source 4 used, the distance from the sheet 1, and the shape of the reflector 5. Since the width direction ranges of the direct light and the reflected light irradiated from the second heating source 4 toward the coating film 2 change, it is preferable that the user appropriately determines it so that the heating unevenness and temperature unevenness in the width direction of the sheet 1 and the coating film 2 are minimized. The same applies to the distance b between the sheet 1 and the second heating source 4. It is preferable that the user appropriately determines and arranges it so that the coating film 2 can be efficiently heated. Even if the sheet 1 is deformed by heat or sways and fluctuates in the vertical direction (the up and down direction of the paper surface), it is preferable to ensure a distance where they do not contact each other. Specifically, it is preferably in the range of 20 to 200 mm.

[0046] Also, the arrangement distance f in the width direction between the first heating source 3 and the second heating source 4 may be suitably arranged according to the distances between the sheet 1 and the coating film 2 and the heating sources and the shapes of the respective reflectors 5. Since the width direction ranges of the direct light and the reflected light irradiated from the first heating source 3 to the sheet 1 and the coating film 2 change depending on the distances and shapes, within the range including the boundary between the portion where the coating film 2 of the sheet 1 is applied and the portion where it is not applied, the user may select and arrange an appropriate distance so that the heating unevenness and temperature unevenness of the sheet 1 and the coating film 2 are minimized.

[0047] The air supply mechanism 17 and the exhaust mechanism 18 in this second embodiment are the same as the examples shown in the air supply mechanism 17 and the exhaust mechanism 18 in the first embodiment, so the description is omitted.

[0048] As a more preferable form of the heating device 22, the shielding member 6 in the second embodiment of FIG. 4b is the same as the example shown in the shielding member 6 in the first embodiment, and thus the description thereof will be omitted.

[0049] Examples of the sheet 1 to be heated by the heating device 12(22) of the present invention include films made of polyester, polyolefin, polyamide, polyphenylene sulfide, acetate, polycarbonate, acrylic resin, etc. Further, this resin film may be a single-layer film or a composite film having a laminated structure of two or more layers. Also, in the above composite film, the resins constituting the inner layer portion and the surface layer portion may be chemically different resins or the same resins. Further, the thickness of the sheet 1 is not particularly limited, but from the viewpoints of mechanical strength and handleability, etc., the thickness is preferably 10 to 500 μm, more preferably 20 to 300 μm.

[0050] The tension per unit width when transporting the sheet 1 is preferably 100 to 3000 N / m. When the tension is within this range, it is difficult for the sheet 1 to meander or flutter vertically in the direction perpendicular to the transport direction, and the possibility of scratches on the surface of the sheet 1 due to friction with the roll and contact with the heating device 12(22) is reduced. Also, since the sheet 1 is less likely to deform even when heated, the possibility of local high-contact-pressure portions occurring between the roll and the sheet 1 and scratches being generated is reduced.

[0051] Examples of the coating liquid to be applied to the surface of the sheet 1 include coating liquids containing acrylic resin, urethane resin, melamine resin, epoxy resin, polyester resin, etc., and the film thickness is preferably 1 to 15 μm. As the solvent of the coating liquid, an aqueous or solvent-based one, etc., is appropriately selected according to the application and the device. Also, the coating liquid may be applied to only one side of the sheet 1 or both sides.

[0052] Examples of the coating method of the coating device include a rod coating method, a gravure coating method, a reverse roll coating method, etc. These methods can be carried out alone or in combination. These coating methods are suitable for obtaining a uniform coating surface with less coating unevenness. In the present invention, it is more preferable to use a rod coating that is easy to adjust the coating amount.

Example

[0053] Next, the above-described embodiment will be specifically described based on examples, but the above-described embodiment is not necessarily limited to the following examples.

[0054] [Sheet to be used] Chips of polyethylene terephthalate (hereinafter abbreviated as PET) with an intrinsic viscosity (also referred to as limiting viscosity) of 0.62 dl / g (measured in o-chlorophenol at 25°C according to the standard of JIS K7367 in 1996) were sufficiently vacuum-dried at 180°C, then supplied to the extruder 7 in FIG. 10 and melted at 285°C, and extruded in a sheet form from the T-shaped die 8 and wound around a mirror-finish cooling drum 9 with a surface temperature of 23°C using the electrostatic application casting method and cooled and solidified to obtain an unstretched film. Subsequently, in the longitudinal stretching machine 10, this unstretched film was heated by a roll group heated to 80°C, and further stretched 3.2 times in the conveying direction while being heated by an infrared heater, and cooled by a cooling roll adjusted to 50°C to obtain a uniaxially stretched sheet 1. The width of the sheet 1 was 900 mm and the thickness was 200 μm.

[0055] Subsequently, a coating liquid was applied to the upper surface of this sheet 1 running at a speed of 50 m / min by the coating liquid application device 11. The width of the coating film 2 was 700 mm, and uncoated portions of 100 mm each were provided at both ends of the sheet 1. The coating liquid application device 11 was of the rod coating type, and the coating rod was a stainless steel round bar with a diameter of 12.7 mm and a length of 1400 mm. The groove specifications of the coating rod were a groove depth of 17 μm and a groove pitch of 100 μm. The coating liquid thickness of the coating film 2 was measured with a moisture meter (RX-200, manufactured by Kurashiki Boseki Co., Ltd.) at the outlet of the coating liquid application device 11 and was 6 μm.

[0056] [Example 1] The heating device 12 was configured as shown in FIGS. 1(a) and 1(b). Here, two units of the air supply mechanism 17 and one unit of the exhaust mechanism 18 were alternately arranged in the conveying direction of the sheet 1. Further, four first heating sources 3, two each, were arranged between the air supply mechanism 17 and the exhaust mechanism 18 with the longitudinal direction in the conveying direction of the sheet 1, and eighteen second heating sources 4, nine each, were arranged between the air supply mechanism 17 and the exhaust mechanism 18 with the longitudinal direction in the width direction of the sheet 1.

[0057] As the first heating source 3, an infrared heater with an output of 5.0 kW per unit, having a length of 260 mm in the conveying direction of the sheet 1 and an outer diameter of φ13 mm, was used. A parabolic reflector 51 with a length of 260 mm in the conveying direction of the sheet 1, a width of 60 mm in the width direction, and a height of 60 mm in the vertical direction was installed at the position of the focus of its parabolic shape so that the axial center of the first heating source 3 coincides. Also, it was installed so that the distance between the sheet 1 and the surface of the infrared heater (corresponding to a in FIG. 1(b)) is 100 mm.

[0058] As the second heating source 4, a short-wavelength infrared heater with a length of 23 mm in the conveying direction of the sheet 1, a width (corresponding to c in FIG. 1b) of 550 mm, and a height of 11 mm was used, and it was installed so that the distance between the sheet 1 and the surface of the short-wavelength infrared heater (corresponding to b in FIG. 1(b)) is 100 mm. Further, the center in the width direction of the sheet 1 was made to coincide with the center position in the width direction of the second heating source 4, and the arrangement distance in the width direction between the axial center of the first heating source 3 and the end point of the second heating source 4 was set to 45 mm.

[0059] The materials of the air supply mechanism 17 and the exhaust mechanism 18 were made of stainless steel (SUS304), with a length of 100 mm in the conveying direction of the sheet 1 and a width of 1000 mm, and were installed with a gap of 100 mm from the sheet 1.

[0060] In addition, the hot air blowing section of the air supply mechanism 17 is a hole nozzle with an aperture ratio of 9.5% having holes with a diameter of 8 mm uniformly distributed in a staggered pattern, and air heated to 100°C was blown out from the holes at an air velocity of 12 m / s. The suction flow rate from the exhaust mechanism 18 was made the same as the total flow rate of the hot air blown out from the air supply mechanism 17.

[0061] With the heating device 12 having these configurations, the coating film 2 was heated from the upper surface of the sheet 1, and the drying of the coating film 2 was completed.

[0062] Thereafter, in the transverse stretching machine 13, the coated sheet was introduced into an oven at 90°C, which is the preheating section, and heated. Subsequently, in an oven at 100°C, which is the stretching section, the coated sheet was stretched 3.5 times in the width direction. Further, in an oven at 220°C, which is the heat setting section, the coated sheet was heat-set while being relaxed 5% in the width direction, and a biaxially stretched film having a coating film formed on one side was obtained. The tension between the longitudinal stretching machine 10 and the transverse stretching machine 13 was controlled by a dancer roll so that the tension per unit width applied in the running direction of the sheet 1 was 8000 N / m. Thereafter, the biaxially stretched film coming out of the transverse stretching machine 13 was wound up by the winding device 14.

[0063] The coating liquid was a mixed liquid in which 5 parts by mass of a melamine-based crosslinking agent (a liquid obtained by diluting imino group-type methylated melamine with a mixed solvent of 10 parts by mass of isopropyl alcohol and 90 parts by mass of water) and 1 part by mass of colloidal silica particles having an average particle diameter of 0.1 μm were added to 100 parts by mass of an emulsion of a polyester copolymer (containing components: 90 mol% of terephthalic acid, 10 mol% of 5-sodium sulfoisophthalic acid, 96 mol% of ethylene glycol, 3 mol% of neopentyl glycol, 1 mol% of diethylene glycol). The viscosity of this coating liquid was 2 mPa·s at a temperature of 25°C. Also, when the temperature of the sheet 1 was measured with a thermograph (CPA-E6, manufactured by FLIR) at the outlet of the coating liquid application device 11, the coating film 2 was 25 to 26°C, and the uncoated portion was 28 to 29°C.

[0064] The method for evaluating the presence or absence of overheating in the uncoated portion was to measure the temperature of the uncoated portion at the outlet of the heating device 12 using a thermograph (CPA-E6, manufactured by FLIR) and check whether the temperature of the highest part was 70°C or lower, which is the allowable temperature. This allowable temperature is a temperature determined by repeating experiments, but since it may be a lower temperature depending on the properties of the sheet 1, it may be appropriately set according to the sheet 1 to be used.

[0065] The method for evaluating the uniformity of heating of the coated portion was to measure the residual moisture of the coating film 2 at the outlet of the heating device 12 using a moisture meter (RX-200, manufactured by Kurashiki Boseki Co., Ltd.). When the residual moisture was confirmed in the range of the central part of the sheet excluding 20 mm from both ends in the width direction of the coating film 2, which becomes the product, it was evaluated as defective with uneven drying, and when the residual moisture was not confirmed, it was evaluated as good with no uneven drying.

[0066] The presence or absence of contact damage on the sheet surface was visually confirmed by unwinding the sheet 1 wound by the winding device 14.

[0067] As a result of manufacturing the sheet with a coating film using this apparatus, since no residual moisture was confirmed in the product part, it was evaluated as having no uneven drying. Also, the temperature of the uncoated portion was 68°C, which was within the allowable range. No damage was confirmed on the surface of the sheet 1.

[0068] [Example 2] Except for changing the reflective material 5 and the second heating source 4 as follows, the coating film was dried under the same apparatus configuration and the same conditions as in Example 1.

[0069] The reflective material 5 provided in the first heating source 3 was changed to a condensing type reflective material 52 having a length of 260 mm in the conveyance direction of the sheet 1, a length of 60 mm in the width direction, and a length of 60 mm in the vertical direction. The condensing type reflective material 52 was installed so that the axial center of the first heating source 3 coincides with the position of the focus of its condensing shape.

[0070] The width direction length of the second heating source 4 (corresponding to c in Fig. 1(b)) was changed to 610 mm, and the width direction arrangement distance between the axial center of the first heating source 3 and the end point of the second heating source 4 was changed to 30 mm.

[0071] As a result of manufacturing the sheet with a coating film using this apparatus, no residual moisture was confirmed in the product part, so it was evaluated that there was no drying unevenness. Also, the temperature of the uncoated part was 66°C, which was within the allowable range, and stable production was possible. No scratches were confirmed on the surface of Sheet 1 either.

[0072] [Example 3] Except for attaching the shielding member 6 as described below, the drying of the coating film was carried out under the same apparatus configuration and the same manufacturing conditions as in Example 1.

[0073] As shown in FIGS. 2(a) and 2(b), between both end portions in the width direction of the sheet 1 and the first heat source 3, a shielding member 6 made of a stainless steel plate (SUS304) having a length of 900 mm, a width of 180 mm, and a thickness of 4 mm in the conveyance direction of the sheet 1 was attached. Regarding the position in the width direction of the shielding member 6, it was installed such that the end point on the sheet center side of the shielding member 6 substantially coincided with both ends in the width direction of the coating film 2. Also, it was installed such that the distance between the surface of the shielding member 6 on the sheet 1 side and the sheet 1 (corresponding to d in FIG. 2(b)) was 30 mm.

[0074] As a result of manufacturing the sheet with a coating film using this apparatus, no residual moisture was confirmed in the product part, so it was evaluated that there was no drying unevenness. Also, the temperature of the uncoated part was 59°C, which was within the allowable range, and stable production was possible. No scratches were confirmed on the surface of Sheet 1 either.

[0075] [Example 4] Except for attaching the shielding member 6 as described below, the drying of the coating film was carried out under the same apparatus configuration and the same manufacturing conditions as in Example 2.

[0076] As shown in FIGS. 2(a) and 2(b), between both end portions in the width direction of the sheet 1 and the first heating source 3, a shielding member 6 made of a stainless steel plate (SUS304) with a length of 900 mm, a width of 180 mm, and a thickness of 4 mm in the conveyance direction of the sheet 1 was attached. Regarding the position of the shielding member 6 in the width direction, the shielding member 6 was positioned outside in the width direction of the coating film 2, and it was installed such that the distance between the end point on the sheet center side of the shielding member 6 and both ends in the width direction of the coating film 2 was 6.5 mm. Further, it was installed such that the distance between the surface of the shielding member 6 on the sheet 1 side and the sheet 1 (corresponding to d in FIG. 2b) was 30 mm.

[0077] As a result of manufacturing the coated sheet with this apparatus, no residual moisture was confirmed in the product portion, so it was evaluated that there was no drying unevenness. Also, the temperature of the uncoated portion was 58°C, which was within the allowable range, and stable production was possible. No scratches were confirmed on the surface of the sheet 1.

[0078] [Example 5] Except that the second heating source 4 was configured as shown in FIGS. 3(a) and 3(b) as follows, the coating film was dried under the same apparatus configuration and the same manufacturing conditions as in Example 1.

[0079] The second heating source 4 had the same configuration as the first heating source 3. With the conveyance direction of the sheet 1 as the longitudinal direction, a total of 14, seven each, were installed between the air supply mechanism 17 and the exhaust mechanism 18 such that the distance between the sheet 1 and the surface of the infrared heater (corresponding to b in FIG. 3(b)) was 100 mm.

[0080] The installation position of the heater in the sheet width direction was set such that the center position in the width direction of the fourth heater from the end in the width direction of the second heating source 4 coincided with the center in the width direction of the sheet 1, and the distance between the centers in the width direction of the heaters of the first heating source 3 and the second heating source 4 (corresponding to e and f in FIG. 3(b)) was 80 mm.

[0081] Also, the output of the infrared heater of the second heating source 4 was set to 5.0 kW per unit, the same as that of the first heating source 3.

[0082] As a result of manufacturing the sheet with a coating film using this apparatus, no residual moisture was confirmed in the product part, so it was evaluated that there was no uneven drying. Also, the temperature of the uncoated part was 65°C, which was within the allowable range, and stable production was possible. No scratches were confirmed on the surface of Sheet 1 either.

[0083] [Example 6] The drying of the coating film was carried out under the same apparatus configuration and the same manufacturing conditions as in Example 5, except that the arrangement of the reflecting material 5 provided in the first heating source 3 and the second heating source 4 was changed as follows.

[0084] The reflecting material 5 provided in the first heating source 3 and the second heating source 4 was changed to a condensing type reflecting material 52 having a length of 260 mm in the conveying direction of Sheet 1, a length of 60 mm in the width direction, and a length of 60 mm in the vertical direction. The condensing type reflecting material 52 was installed such that the axial centers of the first heating source 3 and the second heating source 4 coincided with the position of the focus of its condensing shape.

[0085] Also, with the second heating source 4 having the conveying direction of Sheet 1 as the longitudinal direction, a total of 18 were installed, 9 each between the air supply mechanism 17 and the exhaust mechanism 18, such that the distance between Sheet 1 and the surface of the infrared heater (corresponding to b in Fig. 3(b)) was 100 mm.

[0086] The installation position of the heater in the sheet width direction was set such that the width direction center of the fifth second heating source 4 from the end coincided with the width direction center of Sheet 1, and the distance between the width direction centers of the heaters of the first heating source 3 and the second heating source 4 (corresponding to e and f in Fig. 3(b)) was set to 67 mm.

[0087] As a result of manufacturing the sheet with a coating film using this apparatus, no residual moisture was confirmed in the product part, so it was evaluated that there was no uneven drying. Also, the temperature of the uncoated part was 61°C, which was within the allowable range, and stable production was possible. No scratches were confirmed on the surface of Sheet 1 either.

[0088] [Example 7] The drying of the coating film was carried out under the same apparatus configuration and the same manufacturing conditions as in Example 5, except that the shielding member 6 was attached as follows.

[0089] As shown in FIGS. 4(a) and 4(b), a shielding member 6 made of a stainless steel plate (SUS304) with a length of 900 mm, a width of 180 mm, and a thickness of 4 mm in the conveyance direction of the sheet 1 was attached between both end portions in the width direction of the sheet 1 and the first heat source 3. Regarding the width direction position of the shielding member 6, it was installed such that the point of the end on the sheet center side of the shielding member 6 substantially coincided with both ends in the width direction of the coating film 2. Further, it was installed such that the distance between the surface of the shielding member 6 on the sheet 1 side and the sheet 1 was 30 mm.

[0090] As a result of manufacturing the coated sheet with this apparatus, since residual moisture in the product part was not confirmed, it was evaluated that there was no drying unevenness. Further, the temperature of the uncoated part was 56°C, which was within the allowable range, and stable production was possible. No scratches were confirmed on the surface of the sheet 1.

[0091] [Example 8] Except that the shielding member 6 was attached as follows, drying of the coating film was performed under the same apparatus configuration and the same manufacturing conditions as in Example 6.

[0092] As shown in FIGS. 4(a) and 4(b), a shielding member 6 made of a stainless steel plate (SUS304) with a length of 900 mm, a width of 180 mm, and a thickness of 4 mm in the conveyance direction of the sheet 1 was attached between both end portions in the width direction of the sheet 1 and the first heat source 3.

[0093] Regarding the width direction position of the shielding member 6, the shielding member 6 was positioned outside in the width direction with respect to the coating film 2, and it was installed such that the distance between the point of the end on the sheet center side of the shielding member 6 and both ends in the width direction of the coating film 2 was 6.5 mm. Further, it was installed such that the distance between the surface of the shielding member 6 on the sheet 1 side and the sheet 1 was 30 mm.

[0094] As a result of manufacturing the coated sheet with this apparatus, since residual moisture in the product part was not confirmed, it was evaluated that there was no drying unevenness. Further, the temperature of the uncoated part was 55°C, which was within the allowable range, and stable production was possible. No scratches were confirmed on the surface of the sheet 1.

[0095] [Comparative Example 1] The drying of the coating film was carried out under the same apparatus configuration and the same manufacturing conditions as in Example 1, except for the following changes.

[0096] The first heating source 3 was removed, and the second heating source 4 was changed to a short-wavelength infrared heater with a length of 23 mm in the conveying direction of the sheet 1, a width of 700 mm, and a height of 11 mm in the vertical direction.

[0097] As a result of manufacturing the sheet with the coating film using this apparatus, no residual moisture was confirmed in the product part, so it could be evaluated that there was no uneven drying, and no scratches were confirmed on the surface of the sheet 1. However, the temperature of the uncoated part exceeded the allowable range at 85°C.

[0098] [Comparative Example 2] The drying of the coating film was carried out under the same apparatus configuration and the same manufacturing conditions as in Example 3, except for the following changes.

[0099] The first heating source 3 was removed, and the second heating source 4 was changed to a short-wavelength infrared heater with a length of 23 mm in the conveying direction of the sheet 1, a width of 700 mm, and a height of 11 mm in the vertical direction. Also, the distance between the surface of the shielding member 6 on the side of the sheet 1 and the sheet 1 was changed to 10 mm.

[0100] As a result of manufacturing the sheet with the coating film using this apparatus, no residual moisture was confirmed in the product part, so it was evaluated that there was no uneven drying. However, the temperature of the uncoated part exceeded the allowable range at 71°C. Also, when vibration occurred in the vertical direction perpendicular to the conveying direction during the conveyance of the sheet 1, the shielding member 6 contacted the sheet 1, and the sheet 1 was scratched.

[0101] [Summary] The results of the examples and comparative examples are summarized in Table 1.

[0102]

Table 1

[0103] In Examples 1 to 4, by using a heater equipped with a parabolic or condenser type reflector only at the coated end of the sheet, the incidence of radiant light on the uncoated portions at both ends in the width direction of the sheet could be prevented, and uneven drying could be suppressed. Also, since the temperature of the uncoated portion was lower in Examples 3 and 4 than in Examples 1 and 2, it was found that it is more preferable to shield the uncoated portion using a shielding member.

[0104] In Examples 5 to 8, in addition to the coated ends of the sheet, a configuration is used in which a heater equipped with a parabolic or condenser type reflector is used with the transport direction of the sheet as the longitudinal direction. As a result, the temperature of the uncoated portion was lower in Examples 5 and 6 than in Examples 1 and 2, and in Examples 7 and 8 than in Examples 3 and 4. Therefore, it was found that it is more preferable to use a heater equipped with a parabolic or condenser type reflector in addition to the coated ends of the sheet.

[0105] Comparative Examples 1 and 2 are the results of not using a heater equipped with a reflector at the coated end of the sheet. In Comparative Example 1, since a heater equipped with a reflector was not used at the end, radiant light entered the uncoated portion, and the temperature of the uncoated portion greatly exceeded the allowable temperature, but uneven drying did not occur. In Comparative Example 2, the shielding member was brought close to the sheet, and the temperature of the uncoated portion exceeded the allowable temperature, but uneven drying did not occur. Also, the shielding member contacted the sheet and scratched the sheet.

[0106] By using a heater equipped with a parabolic or condenser type reflector at the coated end of the sheet as in the examples, it is possible to prevent uneven drying and overheating of the uncoated portion even when the distance between the sheet and the shielding member is separated. Also, since the distance between the sheet and the shielding member can be separated, it was found that the possibility of the shielding member contacting the sheet is low and stable production can be achieved.

Industrial Applicability

[0107] The present invention can be applied not only to the heating of coating films but also to the heating of resin films, etc., but the scope of its application is not limited to these.

Description of Symbols

[0108] 1 Sheet 2 Coating Film 3 First Heating Source 4 Second Heating Source 5 Reflective Material 6 Shielding Member 7 Extruder 8 Die 9 Cooling Drum 10 Longitudinal Stretching Machine 11 Coating Film Coating Device 12 Heating Device for Sheet with Coating Film (First Embodiment) 13 Transverse Stretching Machine 14 Winding Device 17 Air Supply Mechanism 18 Exhaust Mechanism 22 Heating Device for Sheet with Coating Film (Second Embodiment) 51 Parabolic Reflective Material 52 Condensing Reflective Material 55 Reflective Material 56 Inclined Shielding Plate a Distance between Sheet 1 and First Heating Source 3 b Distance between Sheet 1 and Second Heating Source 4 c Longitudinal Length of Second Heating Source 4 d Distance between Sheet 1 and Shielding Member 6 e Distance between Second Heating Sources 4 in the Sheet Width Direction f Arrangement Distance in the Width Direction between First Heating Source 3 and Second Heating Source 4 g Irradiation Range of Reflected Light Irradiated on the Sheet by Parabolic Reflective Material 51 h Width Direction Length of Parabolic Reflective Material 15 i Irradiation Range of Irradiated Light Irradiated on the Sheet by Condensing Reflective Material 52 j Width Direction Length of Condensing Reflective Material 16

Claims

1. A sheet coated with a coating liquid except for one or both ends in the sheet width direction, and a heating device for heating the coating liquid of the conveyed sheet, a first heat source that irradiates radiant light onto a region including a boundary between a portion where the coating liquid of the sheet is applied and a portion where the coating liquid is not applied; a second heat source that irradiates radiant light only onto the portion where the coating liquid of the sheet is applied, and the first heat source is in a form composed of a long shape extending in the sheet conveyance direction or a plurality of heat sources arranged in the sheet conveyance direction, a reflecting material that reflects the radiant light toward the sheet, and includes a reflecting material whose shape is convexly curved when observed from the sheet conveyance direction, a heating device for a sheet with a coating film.

2. The heating device for a sheet with a coating film according to Claim 1, wherein the reflecting material is a parabolic reflecting material.

3. The heating device for a sheet with a coating film according to Claim 1, wherein the reflecting material is a condensing reflecting material.

4. A shielding member disposed at a position closer to the sheet than the first heat source and blocking the incident of the radiant light directly irradiated from the first heat source and the radiant light reflected by the reflecting material onto the portion where the coating liquid of the sheet is not applied, in the heating device for a sheet with a coating film according to any one of Claims 1 to 3.

5. A sheet coated with a coating liquid except for one or both ends in the sheet width direction, and a heating device for heating the coating liquid of the conveyed sheet, a first heat source that irradiates radiant light onto a region including a boundary between a portion where the coating liquid of the sheet is applied and a portion where the coating liquid is not applied; a second heat source that irradiates radiant light only onto the portion where the coating liquid of the sheet is applied, and the first heat source and the second heat source are each in a form composed of a long shape extending in the sheet conveyance direction or a plurality of heat sources arranged in the sheet conveyance direction, a reflecting material that reflects the radiant light toward the sheet, and includes a reflecting material whose shape is convexly curved when observed from the sheet conveyance direction, a heating device for a sheet with a coating film.

6. The heating device for a sheet with a coating film according to Claim 5, wherein the reflecting material is a parabolic reflecting material.

7. The heating device for a sheet with a coating film according to Claim 5, wherein the reflecting material is a condensing reflecting material.

8. A heating device for a coated sheet according to any one of claims 5 to 7, comprising a shielding member disposed at a position closer to the sheet than the first heat source and blocking the incident radiation light directly irradiated from the first heat source and the radiation light reflected by the reflector to a portion of the sheet where the coating liquid is not applied.

Images