JP2007275780A - Die coating apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a die coating apparatus capable of performing coating without causing defective surface quality even when changing conditions such as web material and coating material in the die coating apparatus using a backup roller equipped with a soft rubber coating film on its surface. <P>SOLUTION: The die coating apparatus comprises a coating film temperature adjusting means 11 equipped with a temperature adjusting fluid supply device 14 which circulates fluid adjusted to a desired temperature into the backup roller 1, wherein the temperature of a rubber coating film 1a on the surface of the backup roller 1 is adjusted to a temperature at which a rubber hardness suited for the coating can be obtained. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a die coating apparatus that performs coating on a running web such as a sheet or film using a die head.

  Conventionally, as an apparatus for coating a web such as a sheet-like base material with a high viscosity and poor wettability, as shown in FIG. 4, a backup roll 1 having a soft rubber film 1a on its surface and its backup roll 2. Description of the Related Art A die coating apparatus provided with a die head 2 disposed opposite to 1 is known. As shown in FIG. 5, the die coating apparatus presses the tip of the die head 2 against the web 3 that is supported by the backup roll 1 and is conveyed, or between the web 3 and a minute size of 0 to several tens of microns. In a state where the gap is generated, the coating liquid 4 is discharged from the die head 2, and the rubber film 1 a on the surface of the backup roll 1 is slightly deformed by the discharge pressure, whereby the tip of the die head 2 and the web 3 are separated. In the meantime, a coating gap having an appropriate dimension is formed, and the bead 4a formed in the coating gap is stabilized and the wettability is improved by increasing the pressure of the bead portion. Coating.

  By the way, in this type of die coating apparatus, the material and thickness of the web 3 may be changed during production, but in that case, application failure (surface quality failure) occurs even though the same application material is coated. And sometimes it could not be applied. Further, even when the web 3 is the same, application failure may occur or application may not be possible when the application material is switched. This is considered to occur as a result of the balance between the liquid pressure discharged from the tip of the die head and the reaction force from the rubber film 1a of the backup roll, and is a matter requiring reexamination of the coating conditions. Even if the same coating material is coated on the same web, if the line speed is changed to change the coating film thickness or the die discharge flow rate is changed, application failure may occur or application may not be possible. Sometimes it disappeared.

  As a measure for improving coating failure, a method of changing the material viscosity by heating or cooling the coating material can be considered, but changing the material temperature is greatly affected by changes in the flow rate or heat dissipation from the piping, so it lacks stability. When the machine operation and stop are repeated, there is a problem that temperature unevenness occurs and it takes time to recover. In addition, since the temperature of the die head also changes due to a change in the material temperature, there is a problem that the secondary effect due to the temperature change of the precision-processed die head is large and it is difficult to cope with production.

  The present invention has been made in view of such problems, and even when the operating conditions are changed, such as changing the web material or the coating material, or changing the line speed or the die discharge flow rate, it is satisfactorily performed without causing defective coating. It is an object of the present invention to provide a die coating apparatus capable of performing coating.

  In order to solve the above problems, the present inventors have found the following matters as a result of various studies. In other words, poor surface quality or inability to apply when changing operating conditions such as web material changes, coating material changes, line speed changes, die discharge flow rate changes, etc. during production is due to the pressure of the head of the die head and the backup roll. This is because the balance of the deformation amount of the rubber film is lost, and the deformation amount of the rubber film is greatly influenced by the hardness of the rubber film. Therefore, by adjusting the rubber film temperature by adjusting the temperature of the rubber film when the operating conditions are changed, good coating can be performed without causing poor surface quality even if the operating conditions are changed.

  The present invention was made on the basis of such knowledge, and is a backup roll that supports and conveys a web, and at least the backup roll provided with a soft film on the outer peripheral surface of the area that supports the web, and opposed to the backup roll In the die coating apparatus provided with the die head arranged, a film temperature adjusting means for adjusting the temperature of the film on the outer peripheral surface of the backup roll is provided.

  Here, as the film temperature adjusting means, various forms can be used, and one form includes a temperature adjusting fluid supply device that supplies a temperature adjusted fluid into the backup roll. be able to.

  As another example of the film temperature adjusting means, there can be mentioned one provided with a temperature adjusting gas spraying device for spraying a temperature-adjusted gas on the backup roll surface. In addition, this temperature control gas spraying device and the above-described temperature control fluid supply device may be used alone or in combination.

  It is preferable that a device for measuring the film temperature of the backup roll is further provided in the die coating apparatus having the above configuration.

  Moreover, it is preferable that the die coating apparatus having the above-described configuration is further provided with a local cooling means for locally cooling the region of the backup roll film through which the edge of the web passes.

  Since the die coating apparatus of the present invention is provided with the film temperature adjusting means, when the operating conditions are changed such as web material change, coating material change, line speed change, die discharge flow rate change during production, a backup roll is provided by the film temperature adjusting means. By adjusting the temperature of the soft film on the surface, the rubber hardness can be adjusted to a value suitable for the operating conditions, and good coating can be performed without causing poor surface quality. In addition, when a surface quality defect occurs during application, the surface temperature defect can be avoided and good coating can be performed by adjusting the film temperature of the backup roll. Here, the film temperature adjustment of the backup roll can be performed stably with an accuracy of, for example, about ± 1 ° C. Further, since it is less susceptible to machine operation and stoppage, it can be quickly adjusted to the desired temperature, Excellent production response.

  Here, if a device for measuring the film temperature of the backup roll is provided in the die coater, the rubber hardness of the film can be easily determined by measuring the film temperature, and the temperature of the film can be easily adjusted. At the same time, the coating conditions can be easily monitored by monitoring the film temperature during operation.

  In addition, if a local cooling means for locally cooling the area of the backup roll film through which the edge of the web passes is provided, the rubber hardness of that portion can be increased locally, and the edge of the web passes through. The damage | wound which may be produced by the tension | tensile_strength added to a web in the membrane | film | coat area | region to perform can be prevented. Note that the local cooling range of the coating is, of course, a range that does not adversely affect the coating.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention shown in the drawings will be described. FIG. 1 is a schematic perspective view of a die coating apparatus according to an embodiment of the present invention. Components identical or similar to those in the conventional example shown in FIGS. 4 and 5 are denoted by the same reference numerals. The die coating apparatus according to this embodiment also includes a backup roll 1 that conveys a web 3 such as a sheet-like base material wrapped around a part of the outer peripheral surface, and a die head 2 that is disposed to face the backup roll 1. Yes. The backup roll 1 is provided with a rubber film 1a as a soft film in a region where at least the web 3 of the outer peripheral surface is supported and conveyed, and can be deformed by the discharge pressure of the coating liquid from the die head 2. Here, the rubber hardness at normal temperature of the rubber coating 1a is determined so that it can be satisfactorily applied under the main application conditions in this die coater, and is usually within a range of 65 to 80 degrees. It is set to a valid value.

  The die coating apparatus further includes a film temperature adjusting means 11 for adjusting the temperature of the rubber film 1 a on the outer peripheral surface of the backup roll 1 and a temperature measuring device 12 such as a thermography for measuring the film temperature of the backup roll 1. The film temperature adjusting means 11 used in this embodiment supplies a temperature-adjusted fluid in the backup roll, for example, hot water heated to a desired temperature or cold water cooled to a desired temperature, and circulates it. 14 is provided. The backup roll 1 is provided with a fluid passage so that the rubber film 1a on the surface can be uniformly heated or cooled by circulating the fluid therein.

  Also in the die coating apparatus having the above configuration, as shown in FIG. 5, the tip of the die head 2 is pressed against the web 3 supported by the backup roll 1 or conveyed between the web 3 as in the conventional case. In a state where the gap is generated at a position where a minute gap of 0 to several tens of microns is generated, the coating liquid 4 is discharged from the die head 2, and the rubber film 1a on the surface of the backup roll 1 is minutely deformed by the discharge pressure. A coating gap having an appropriate dimension is formed between the tip of the web 2 and the web 3, the bead 4 a formed in the coating gap is stabilized, and the wettability is improved by increasing the pressure of the bead portion. A uniform coating is performed in the width direction with a film thickness of. At this time, in the state where the rubber film 1a of the backup roll 1 is at a normal temperature, when the satisfactory application can be performed without causing poor surface quality, the temperature adjusting fluid supply device 14 is not operated, and the backup roll 1 Is applied at room temperature.

  Next, when changing the operation conditions such as web material change, application material change, line speed change, die discharge flow rate change, etc. during production, the rubber hardness of the rubber coating 1a is excellently applied under new operation conditions. The temperature of the rubber film 1a of the backup roll 1 is adjusted so that the hardness can be increased. This rubber film temperature adjustment is performed by sending a heated or cooled fluid (hot water or cold water) from the temperature adjusting fluid supply device 14 to the backup roll 1 while measuring the temperature of the rubber film 1a by the temperature measuring device 12. Circulating and controlling the fluid temperature so that the rubber film temperature becomes a desired temperature. Then, the circulation of hot water or cold water from the temperature adjusting fluid supply device 14 to the backup roll 1 is continued, and coating is performed in a state where the rubber film 1a is kept at a predetermined temperature. Thereby, it is possible to perform good coating without causing poor surface quality even under new operating conditions. The temperature of the rubber film 1a that can be satisfactorily applied under new operating conditions may be obtained in advance by a test, or the temperature is changed while actually operating to obtain a favorable temperature condition. May be. During the application operation, even when surface quality is poor due to some disturbance or application becomes impossible, the temperature of the fluid fed from the temperature adjusting fluid supply device 14 to the backup roll 1 is changed, and the rubber coating 1a is changed. By adjusting the temperature, good coating can be resumed.

  In the above operation, while the temperature of the rubber film 1a is measured by the temperature measuring device 12, the temperature circulated from the temperature adjusting fluid supply device 14 to the backup roll 1 is controlled so that the rubber film 1a has a predetermined temperature. However, the present invention is not limited to this method, and the relationship between the temperature of the rubber film and the temperature of the fluid to be sent to the backup roll 1 is obtained in advance, and the fluid sent to the backup roll 1 by the temperature adjusting fluid supply device 14 is transferred to the rubber film 1a. The temperature may be adjusted to a temperature that can be set to a predetermined temperature, and the fluid may be circulated. When this method is adopted, the temperature measurement of the rubber film 1a can be omitted, and therefore the temperature measuring device 12 can be omitted. However, even in this case, it is preferable to provide the temperature measuring device 12 because the temperature of the rubber film 1a during the coating operation can be monitored and abnormality can be detected promptly.

  In the above-described embodiment, the temperature-adjusted fluid is sent to almost the entire width of the backup roll 1 to adjust the rubber film 1a of the backup roll 1 to a constant temperature over the entire width. However, when the backup roll 1 is long, etc. In such a case, a temperature difference that cannot be ignored in the width direction of the backup roll 1 may occur in the configuration in which the same fluid is simply flown over almost the entire area of the backup roll 1. Therefore, in order to avoid the temperature difference, the inside of the backup roll may be divided into a plurality of regions in the width direction, and fluids having different temperatures may be supplied to each region. By adopting this configuration, the temperature of the rubber coating 1a can be made more uniform in the width direction. In some cases, a temperature difference can be positively given. Normally, the rubber film 1a of the backup roll 1 is manufactured so that the rubber hardness thereof is uniform over the entire length, but the hardness unevenness may occur due to a manufacturing error or the like. In such a case, the hardness of the rubber film 1a can be adjusted so as to approach evenly by appropriately varying the temperature of the rubber film 1a in the width direction, thereby enabling better application. It becomes.

  By the way, it is desirable that the hardness of the rubber film 1a of the backup roll 1 is constant in the application region with respect to the web 3, but in the region where the edge of the web 3 passes outside the application region, the rubber hardness may be increased. desirable. That is, in the region where the edge of the web of the rubber coating 1a passes, the edge may bite into the rubber coating 1a due to the tension of the web 3, and this region may be damaged. In particular, the rubber coating 1a of the backup roll 1 is heated. When the rubber hardness is lowered, the web edge is likely to be scratched. Therefore, it is preferable to increase the rubber hardness so as not to be easily scratched. For this reason, the temperature of the rubber film 1a in this region does not increase so much. It is desirable to keep it down. Therefore, it is preferable that the die coater is provided with a local cooling means for locally cooling the region of the rubber film 1a on the backup roll 1 where the web edge passes.

  FIG. 2 shows a die coating apparatus provided with this local cooling means. The local cooling means 16 includes a blower 16a that blows out air and a nozzle 16b that blows air from the blower 16a onto a region of the rubber film 1a of the backup roll 1 through which the web edge passes. Although only one local cooling means 16 is shown in the drawing, two local cooling means 16 are provided corresponding to the regions through which the edges on both sides of the web 3 pass. Although not shown, a temperature adjusting fluid supply device is also provided for adjusting the temperature of the rubber coating 1a by feeding hot water or cold water into the backup roll 1 as in the die coating apparatus shown in FIG. .

  In the die coating apparatus having the structure shown in FIG. 2, the rubber film 1a is adjusted so as to have a temperature that exhibits rubber hardness suitable for coating, and even when the coating conditions are changed, the surface quality is satisfactory. In addition, during the coating operation, the local cooling means 16 blows air onto the region of the rubber coating 1a through which the web edge passes, thereby suppressing the temperature rise of the rubber coating 1a in that region and It has the advantage that it is possible to suppress a decrease in hardness and to suppress the occurrence of scratches due to the web edge. In addition, although the local cooling means 16 shown in FIG. 2 is the structure which sprays air on the backup roll 1, it is good also as a structure which can spray the cooled air as needed, and, thereby, the rubber membrane | film | coat 1a is further layered. It can be cooled and the rubber hardness can be increased to prevent the occurrence of scratches. Further, the local cooling means 16 is configured to cool by blowing air onto the rubber film 1a. However, the local cooling means is not limited to this structure, and any means can cool a desired region of the rubber film 1a. For example, the structure is arbitrary. For example, a mechanism for circulating a low-temperature fluid may be provided inside the region of the backup roll 1 through which the web edge passes, and the mechanism may be used as a local cooling means.

  FIG. 3 is a schematic perspective view showing a die coating apparatus according to another embodiment of the present invention. In this die coating apparatus, a temperature-adjusted gas spraying device 18 that sprays a temperature-adjusted gas on the surface of the backup roll 1 is used as the film temperature adjusting means. The temperature adjusting gas blowing device 18 includes a blower 18a for sending out air, an air temperature adjuster 18b for adjusting the air from the blower 18 to a desired temperature, and a nozzle 18c for blowing the temperature-adjusted air onto the surface of the backup roll 1. The nozzle 18c is configured to blow air over substantially the entire width of the backup roll 1 surface. Also in this die coating apparatus, the rubber film 1a of the backup roll 1 can be heated or cooled so as to have a temperature that exhibits rubber hardness suitable for application, and even when the application conditions are changed, the surface quality is poor. It is possible to perform a good coating without any.

  In the embodiment of FIG. 3, the air at the same temperature is blown over the entire width of the backup roll 1, but if necessary, the air blowing width of the temperature adjusting gas blowing device 18 is reduced to reduce the width of the backup roll 1. It is good also as a structure which provides a several temperature control gas spraying device so that air can be sprayed to the several location of a direction, respectively. By adopting this configuration, the temperature of the rubber film 1a on the surface of the backup roll 1 can be adjusted more uniformly in the width direction by changing the temperature of the air blown to different portions of the backup roll 1 in the width direction. If necessary, a temperature difference can also be given.

  In the embodiment shown in FIG. 3, as described above, the rubber film 1a on the surface of the backup roll 1 may be damaged by the edge of the web in the region where the edge of the web passes. It is desirable to cool, and it is preferable to provide a local cooling means for locally cooling the portion.

  Using a die head 2 having a discharge width of 400 mm and a slit gap of 500 μm, and a backup roll 1 having a rubber film 1 a of a rubber hardness of 75 ° and a material NBR, a coating liquid having a viscosity of 2000 cps is applied to a web 3 of a PET film having a thickness of 50 μm. Application was performed at a flow rate of 400 cc / min and a web speed of 20 m / min to confirm that application was possible.

  Next, only the film thickness of the web 3 was changed to 75 μm and 100 μm, and coating was performed under the same conditions as described above. However, when the web film thickness was 125 μm, a coating film could not be formed. Application was not possible. Then, when warm water was sent into the backup roll 1 and the rubber film 1a was heated, application was possible at a temperature of the rubber film 1a of 45 ° C. (thermographic measurement). Furthermore, when the thickness of the web 3 was 188 μm, it could not be applied at a temperature 45 ° C. of the rubber film 1a, but could be applied at a temperature 70 ° C. of the rubber film 1a. The results are summarized as shown in Table 1.

  As is apparent from this result, it was confirmed that even when application was not possible due to application condition changes, application was possible by adjusting the temperature of the rubber film.

  Further, when continuously operating at a web thickness of 125 μm, a rubber film temperature of the backup roll 1 of 45 degrees, and a web 3 tension of 250 N, the local cooling means shown in FIG. No. 16 was used to forcibly cool by blowing air, and the region through which the other edge passed was not cooled and was kept warm. In this state, the web 3 was allowed to flow for about 20000 m, and then the surface of the rubber film 1a was visually inspected. As a result, no damage was observed on the side cooled by air blowing, but scratches were generated on the uncooled side. Therefore, it was confirmed that the occurrence of scratches due to the web edge can be prevented by cooling the rubber film.

  The preferred embodiment of the present invention has been described above, but the present invention is not limited to this embodiment, and it is needless to say that the present invention can be appropriately changed within the scope of the claims.

Schematic perspective view of a die coating apparatus according to an embodiment of the present invention Schematic perspective view showing a die coat apparatus provided with local cooling means The schematic perspective view of the die-coating apparatus which concerns on other embodiment of this invention. Schematic perspective view of a conventional die coating apparatus Schematic cross-sectional view showing enlarged liquid discharge part in die coating device

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Backup roll 1a Rubber film 2 Die head 3 Web 11 Film temperature adjustment means 12 Temperature measurement apparatus 14 Temperature adjustment fluid supply apparatus 16 Local cooling means 16a Blower 16b Nozzle 18 Temperature adjustment gas spraying apparatus 18a Blower 18b Air temperature adjustment apparatus 18c Nozzle

Claims (5)

  A backup roll for supporting and transporting a web, the backup roll having a soft film on at least the outer peripheral surface of the region supporting the web, the die head disposed opposite to the backup roll, and the outer peripheral surface of the backup roll A die coater provided with a film temperature adjusting means for adjusting the temperature of the film.   The die coating apparatus according to claim 1, wherein the film temperature adjusting means includes a temperature adjusting fluid supply device for supplying a temperature adjusted fluid into the backup roll.   The die coating apparatus according to claim 1 or 2, wherein the coating temperature adjusting means includes a temperature adjusting gas spraying device for spraying a temperature-adjusted gas on the backup roll surface.   The die coating apparatus according to any one of claims 1 to 3, further comprising an apparatus for measuring a film temperature of the backup roll.   5. The die coating apparatus according to claim 1, further comprising a local cooling unit that locally cools a region of the backup roll film through which a web edge passes.

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