JP6766379B2 - Drying device and drying method - Google Patents

Description

The present invention relates to a drying device and a drying method.

There is a technique of forming a liquid coating film on a sheet and drying it to form a film. In order to obtain a uniform film by such a film forming technique, it is important to first form a coating film having a uniform thickness and at the same time perform uniform drying.

A typical drying device is an air flow drying device. The airflow drying device includes a device that blows airflow directly onto the coating film and a device that blows airflow onto the back surface where the coating film is not formed. Here, the former will be referred to as a front airflow drying device, and the latter will be referred to as a backside airflow drying device.

The surface airflow drying device has an advantage of high drying efficiency. On the other hand, there are problems that only the surface of the coating film is dried and the inside is likely to be in a state of a surface film that is not dried, and bubbles are likely to be generated due to rapid drying. The backside airflow dryer solves this problem. However, the back surface airflow drying device also has a problem that the airflow wraps around the coating film forming surface from the end portion of the sheet, the end portion dries quickly, and the uniformity deteriorates.

A technique for a drying device that solves the above problems is disclosed in, for example, Patent Document 1. FIG. 10 is a cross-sectional view showing this drying device. The drying device has a blow-out nozzle 104 that blows warm air 103 onto the back surface of the sheet 102 on which the coating film 101 is formed. Then, the counter plates 105 for limiting the air flow to a range narrower than the width of the sheet 102 and blowing it on the back surface of the sheet are installed at both ends of the blow nozzle 104. In Patent Document 1, it is desirable that the range in which warm air is blown is 80% or more and 100% or less of the width of the coating film, and is symmetrical with respect to the center line of the sheet 102. With the above configuration, warm air that wraps around the coating film forming surface from the edge of the sheet 102 is eliminated, so that the drying uniformity of the coating film can be ensured.

Japanese Unexamined Patent Publication No. 2014-56840

However, the technique of Patent Document 1 has a problem that the end portion of the coating film is distorted. With this technique, the part of the sheet located within the warm air blowing range is warmed, and the part outside the warm air blowing range is not warmed. Therefore, a difference in the amount of expansion or contraction is generated between the two portions according to the temperature difference. This difference causes distortion near the end of the coating film located at the boundary between the two. That is, the strain is fixed on the coating film after drying.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a drying apparatus for uniformly drying a coating film without distortion.

In order to solve the above problems, the drying device of the present invention has a nozzle that blows airflow on one surface of the sheet and a windshield that is located near the edge of the sheet to reduce the wraparound of the airflow to the opposite surface of the sheet. Has a wall.

The effect of the present invention is to be able to provide a drying device that uniformly dries the coating film without distortion.

It is sectional drawing which shows the 1st Embodiment. It is a side view which shows the 1st Embodiment. It is sectional drawing which shows the 2nd Embodiment. It is sectional drawing which shows the general drying apparatus. It is sectional drawing which shows the 3rd Embodiment. It is sectional drawing which shows the 4th Embodiment. It is sectional drawing which shows an example of 5th Embodiment. It is sectional drawing which shows another example of 5th Embodiment. It is sectional drawing which shows the 6th Embodiment. It is a top view which shows the specific example of the windbreak wall of 6th Embodiment. It is sectional drawing which shows the drying apparatus of Patent Document 1. FIG.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. However, although the embodiments described below have technically preferable limitations for carrying out the present invention, the scope of the invention is not limited to the following. Note that similar components in each drawing may be given the same number and description may be omitted.

(First Embodiment)
FIG. 1 is a cross-sectional view showing the first embodiment. The drying device includes a blow-out nozzle 3 that blows an air flow 2 onto one surface of the sheet 1 and a windbreak wall 4 that is located near both side ends of the sheet 1 and reduces the wraparound of the air flow 2 to the opposite surface of the sheet. Have. Here, reducing the wraparound means reducing the wraparound air volume of the airflow 2 to the extent that the wraparound airflow does not affect drying.

FIG. 2 is a side view when the drying device is viewed from the direction perpendicular to the sheet traveling direction 5, that is, from the lateral direction, when the sheet 1 advances in the direction perpendicular to the paper surface in the drying apparatus of FIG. The windbreak wall 4 has a width that covers at least the airflow blowing range of the blowing nozzle 3. For example, the windbreak wall 4 is made slightly larger than the blowout nozzle 3. Note that FIG. 2 also illustrates the arrangement of the delivery roll 6 and the take-up roll 7 when the roll-to-roll method is used.

With the above configuration, it is possible to reduce the amount of wraparound airflow while uniformly blowing the airflow onto one surface of the sheet. Therefore, it is possible to provide a drying device that uniformly dries the sheet without distortion.

(Second Embodiment)
FIG. 3 is a cross-sectional view showing a second embodiment. The drying device has a blowout nozzle 30 that blows an airflow 20 onto one side of the sheet 10 and a plate-shaped windbreak wall 40 that extends from the vicinity of the end of the sheet 10 in the direction opposite to the nozzle. A coating film 50 is formed on one side of the sheet 10. When the roll-to-roll method is used, the sheet 10 is assumed to travel in a direction perpendicular to the paper surface. That is, in the case of the roll-to-roll method, FIG. 3 shows a cross-sectional view of the sheet in the width direction. Although not shown, the windshield wall 40 has a width that covers the airflow blowing range of the blowing nozzle 30 in the direction perpendicular to the paper surface.

The drying device dries the coating film 50 by blowing an air flow 20 onto the surface opposite to the coating film forming surface (hereinafter, also referred to as the front surface) (hereinafter, also referred to as the back surface). If the coating film 50 is, for example, a resin containing an organic solvent or a thermosetting resin, hot air having a temperature higher than room temperature can be used as the air flow 20. In such a case, the sheet 10 is heated by the hot air, and the heat of the sheet 10 propagates to the coating film 50 to dry the coating film 50. However, in this embodiment, the temperature of the airflow 20 is arbitrary.

Here, for comparison, drying using a drying device without a windshield wall 40, that is, a general drying device will be described. FIG. 4 is a cross-sectional view showing the above-mentioned general drying apparatus. The drying device blows the airflow 20 blown out from the blowout nozzle 30 onto the back surface of the sheet 10 on which the coating film 50 is formed. The airflow 20 wraps around the surface of the sheet 10 in the vicinity of the widthwise end of the sheet 10 as shown by the arrow 20a in FIG. Due to the action of the airflow 20a that wraps around in this way, the vicinity of the widthwise end portion of the coating film 50 dries faster than the widthwise central portion.

On the other hand, in the drying apparatus of the present embodiment shown in FIG. 3, most of the airflow blown to the widthwise end of the sheet 10 by the windshield wall 40 is guided to the outside of the windshield wall 40, and the sheet of the airflow 20 10 The wraparound to the surface is suppressed. Therefore, the windshield wall 40 is arranged in the vicinity of the widthwise end portion of the sheet 10 so as not to come into contact with the sheet 10. Specifically, a distance of, for example, about 1 to 10 mm is provided between the sheet 10 and the windbreak wall 40. The reason for providing such an interval is to prevent the windshield wall 40 and the sheet 10 from coming into contact with each other when the sheet 10 travels. Therefore, it may be adjusted according to the blur width of the sheet 10.

With such an arrangement, a part of the airflow 20 escapes to the surface side through the gap between the sheet 10 and the windbreak wall 40. In FIG. 2, this is indicated by a dotted arrow. However, the airflow of this airflow is significantly reduced as compared with the case without the windshield wall 40. The Coanda effect also produces a component that travels along the windbreak wall 40. As a result, excessive drying of the end portion of the coating film 50 due to the wraparound of the air flow 20 is suppressed, and uniformity is ensured. Further, since the air flow is uniformly blown over the entire sheet 10, the coating film 50 after drying does not have the distortion as in Patent Document 1.

As described above, according to the present embodiment, it is possible to configure a drying device that uniformly dries the coating film without distortion.

(Third Embodiment)
In the second embodiment, the windshield wall is stretched from the vicinity of the edge of the sheet to the side opposite to the blowout nozzle, but the same effect can be obtained by stretching in a different direction. FIG. 5 is a cross-sectional view showing an example of a drying device that realizes this. In the example of FIG. 5, the windshield wall 41 has a shape extending from the vicinity of the end portion of the sheet 10 in a direction substantially parallel to the surface of the sheet 10.

When the windbreak wall 41 has such a shape and arrangement, most of the airflow 20 blown to the end of the sheet 10 passes through the outer end of the windbreak wall 41 and goes around to the surface of the windbreak wall 41. Proceed like an umbrella. This situation is indicated by the arrow 20b in FIG. In this case, the airflow wraps around to the surface side as in a general drying device, but it does not affect the drying of the coating film 50 because it is far from the end of the coating film 50. Further, a part of the airflow 20 passes through the gap between the sheet 10 and the windshield wall 41. In FIG. 5, this airflow is indicated by a dotted arrow. However, the airflow of this airflow is significantly reduced as compared with the case where the windshield wall 40 is not provided. Therefore, it is possible to suppress excessive drying of the end portion of the coating film 50 due to the wraparound of the airflow 20.

Next, a specific example of the size of the windbreak wall will be described. For example, when the temperature of the airflow 20 is 80 ° C. and the wind speed is 25 m / s as the drying conditions, if the length extending outward of the sheet 10 of the windshield wall 41 is about 10 cm, the airflow 20 wraps around. , It is possible to prevent the coating film 50 from being affected by drying. If the wind speed is lower than this, the length of the windbreak wall 41 may be shorter, and if the wind speed is higher, the length of the windbreak wall 41 may be adjusted to be longer. The distance between the sheet 10 and the windbreak wall 41 is set so that the sheet 10 does not come into contact with the windshield wall 41. Specifically, if the device has normal accuracy, it can be about 1 to 10 mm. In the above description, the stretching direction of the windbreak wall is substantially parallel to the surface of the sheet, and in the second embodiment, it is substantially perpendicular to the surface of the sheet, but the same effect can be obtained in other directions. It is possible.

As described above, according to the present embodiment, it is possible to configure a drying device that uniformly dries the coating film without distortion, as in the second embodiment.

(Fourth Embodiment)
It is also possible to extend the windshield wall from the vicinity of the edge of the sheet on the blowout nozzle side toward the outside of the sheet. An example is shown in FIG. The windshield wall 42 has a shape extending from the vicinity of the widthwise end of the sheet 10 on the blowout nozzle 30 side in a direction away from the sheet 10. In this case, as in the example of FIG. 5, the airflow 20 toward the widthwise end of the sheet 10 is mostly along the outside of the windbreak wall 42, as indicated by the arrow of 20c, on the surface of the windbreak wall 42. Wrap around to the side. Since this airflow is separated from the end of the coating film 50 by the windshield wall 42, it does not contribute to the drying of the end of the coating film 50. Therefore, the same effect as that of the third embodiment can be obtained. In the case of this example as well, a part of the airflow passes through the gap between the sheet 10 and the windshield wall 42 indicated by the dotted arrow in FIG. 6, but since the airflow is significantly reduced, it is the end of the coating film 50. The effect on the drying of the part is small.

As described above, also in this embodiment, it is possible to configure a drying device that uniformly dries the coating film without distortion, as in the third embodiment.

(Fifth Embodiment)
In the first to fourth embodiments, the example in which the windbreak wall is a solid having no opening has been described, but the windbreak wall may have an opening. FIG. 7 shows an example in which a windbreak wall 43 having an opening is used as the windbreak wall in the same configuration as the second embodiment. Other configurations are the same as in the second embodiment. Even if the windbreak wall 43 is a plate-like body having a plurality of through holes as shown in FIG. 6, the airflow 20 that wraps around the surface of the coating film 50 through the opening is small, so that the airflow 20 is almost the same. The effect is obtained.

Further, also in the configuration of the third embodiment, it is possible to use a windbreak wall having an opening. An example of such a configuration is shown in FIG. FIG. 8 is a cross-sectional view when a windbreak wall 44 having a plurality of through holes is used as the windbreak wall. In this configuration, as compared with the third embodiment, the airflow 20 passing through the front surface side of the windbreak wall 44 through the through hole indicated by the dotted arrow in the figure increases. However, the effect is small because the air volume of the wraparound airflow is significantly reduced as compared with the case where there is no windbreak wall.

As described above, even if a windbreak wall having an opening is used, it is possible to construct a drying device that reduces the wraparound of the air flow to the sheet surface side and uniformly dries the coating film without distortion.

(Sixth Embodiment)
FIG. 9 is a cross-sectional view showing the drying apparatus of the sixth embodiment. This embodiment has almost the same configuration as the example shown in FIG. 7 of the fifth embodiment, but the structure of the windbreak wall is different. The windbreak wall 45 of the present embodiment has a shape in which the area ratio of the openings gradually increases as the distance from the sheet increases. When the windbreak wall does not have an opening, the airflow is turbulent at the tip of the windbreak wall on the side far from the sheet 10 due to the sudden disappearance of the windbreak wall. On the other hand, in the present embodiment, this turbulence can be reduced by gradually increasing the opening.

FIG. 10 shows a specific example of the shape of the windbreak wall 45. In each figure, the upper part of the paper surface is the direction away from the sheet. The windbreak wall 45a of FIG. 10A is formed with a higher density as the circular openings 46a of the same size are separated from the sheet. The windbreak wall 45b of FIG. 9B has an opening 46b whose area increases as the distance from the sheet increases. The windbreak wall 45c of FIG. 9C has a slit-shaped opening 46c whose area increases as the distance from the sheet increases. The windbreak wall 45d of FIG. 9D has a corrugated opening 46d that becomes wider as the distance from the sheet increases. These are just examples and can be in various shapes.

As described above, according to the present embodiment, it is possible to configure a drying device that reduces the turbulence of the air flow.

The present invention has been described above using the above-described embodiment as a model example. However, the present invention is not limited to the above embodiment. That is, the present invention can apply various aspects that can be understood by those skilled in the art within the scope of the present invention.

1, 10, 102 Sheet 2, 20 Airflow 3, 30, 104 Blow-out nozzle 4, 40, 41, 42, 43, 44, 45 Windbreak wall 46 Opening 50, 101 Coating film

Claims (7)

Possess a nozzle for blowing an air flow on one side of the sheet, and Saegikazekabe that located in the vicinity of the end portion of the sheet to reduce the diffraction of the air flow to the opposite surface of the sheet, and
The windbreak wall has an opening and
The area of the opening gradually increases in the direction away from the sheet.
Drying apparatus according to claim and this. The drying apparatus according to claim 1, wherein the windbreak wall has a plate shape extending from the vicinity of the end portion of the sheet in a direction away from the sheet. The drying apparatus according to claim 2, wherein the direction away from the sheet is a direction from the one surface toward the surface opposite to the one surface. The drying apparatus according to any one of claims 1 to 3, wherein the opening is divided into a plurality of parts. A coating film is formed on the first surface of the sheet,
Airflow is blown onto the second surface, which is opposite to the first surface.
A windbreak wall that reduces the wraparound of the airflow to the first surface is arranged near the edge of the sheet .
The windbreak wall has an opening, and the area of the opening gradually increases in a direction away from the sheet.
The drying method of a coating film, wherein the this. The method for drying a coating film according to claim 5 , wherein the windbreak wall has a plate shape extending from the vicinity of the widthwise end portion of the sheet in a direction away from the sheet. The method for drying a coating film according to claim 6 , wherein the direction away from the sheet is a direction from the second surface toward the first surface.

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