JP2012071284A - Coating film manufacturing method and coater - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a gravure coater that prevents the amount of high-viscosity liquid to be applied from varying in a region where shearing speed of coating liquid is low.SOLUTION: A liquid receiving pan 11 has a duplex circular arc structure. One edge 11u of two edges in the longitudinal direction of the duplex circular arc liquid-receiving pan 11, is located on the side where a gravure roll 12 having coated a base 1 moves to come in contact with the coating liquid. A liquid inlet 31 for supplying the coating liquid to a liquid storage part 11a of the liquid receiving pan 11 is provided in an inner member 21 of the edge 11u that constitutes the liquid receiving pan 11. A protruding buffering zone 32 is provided on the bottom of an outer member 22 that constitutes the liquid receiving pan 11. A liquid supply pump 17 supplies the coating liquid to the buffering zone 32. The coating liquid is supplied to the liquid inlet 31 via a communication path 24 between the inner member 21 and the outer member 22, to supply the liquid from the liquid inlet 31 to the liquid storage part 11a of the liquid receiving pan 11.

Description

  The present invention relates to a method for producing a coating film capable of suppressing coating amount distribution (variation in coating amount) and performing stable coating when a high-viscosity coating liquid is applied with a roll coater such as a gravure coater. And a coating apparatus.

The gravure coating method is currently used as a coating method for various coating liquids.
With the gravure coating method, if the coating liquid can be placed on a gravure roll, it can be easily applied to the substrate by scraping off the excess coating liquid with a doctor blade. The range is wider than other coating methods.
However, when applying the coating liquid to the gravure roll, the gravure roll is immersed in a container filled with the coating liquid in a container called the liquid receiving pan, so the coating liquid in the liquid receiving pan is managed. Hard to do. For example, since the solvent in the coating liquid evaporates in the liquid receiving pan that is opened to the air, the viscosity of the coating liquid increases in the liquid receiving pan, which causes a problem in quality control of the coated product.

Such an increase in the viscosity of the coating liquid in the liquid receiving pan generally causes the coating liquid in the liquid receiving pan to circulate again to the liquid injection side while extracting a certain amount from the waste liquid mouth, This is avoided by making the inside coating liquid state constant.
However, in order to circulate the coating liquid in the liquid receiving pan, it is essential that the viscosity of the coating liquid is low to some extent, and in the case of a high viscosity liquid, it is difficult to circulate the coating liquid. In particular, since it is difficult for the coating liquid to be sheared in the state where it is in the liquid receiving pan, in the region where the shear rate is low, in the case of a coating liquid having a high viscosity, it is difficult to handle, for example, a retention portion of the coating liquid is formed in the liquid receiving pan. Become.

By the way, from the viewpoint of quality control of the coating liquid, it is effective to make the flow of the coating liquid in one direction with as few open portions as possible. Although the coating method is different from the gravure method, die coating is a good example.
Also, as disclosed in Patent Document 1, a method of using a fountain-type nozzle for directly discharging a coating liquid onto a gravure roll has been proposed in order to take advantage of good die coating.

Japanese Patent Laid-Open No. 5-128512

However, in the case of die coating, there is no open part and the flow of the coating liquid can be unidirectional, but when applying a coating liquid with a high viscosity, a coating amount distribution occurs in the width direction of the substrate. It is not preferable.
The method proposed in Patent Document 1 is preferable up to the point where the coating liquid is applied to the gravure roll because there is no open portion and the flow of the coating liquid can be realized in one direction. In order to apply the coating liquid by discharging from the mold nozzle, unless the gap between the roll and the nozzle is set appropriately, the distribution of the coating amount is caused.

In the method described in Patent Document 1, although the doctor blade and the nozzle are integrated, it is possible to suppress the coating amount distribution by scraping off separately with the doctor blade. However, since the fountain type nozzle is used, there is a problem that the apparatus becomes heavy and large, and the introduction cost of the apparatus is high.
Therefore, the present invention has been made paying attention to the above-mentioned conventional unsolved problems, and it is possible to control the physical properties of the coating liquid by suppressing the distribution of the coating amount even for a liquid having a high viscosity. It aims at providing the manufacturing method and coating apparatus of a film | membrane.

The present inventor has found that the above problem can be solved by specifying a method for supplying the coating liquid to the liquid receiving pan, and has completed the present invention.
That is, in the invention according to claim 1 of the present invention, the coating liquid adhered to the gravure roll is brought into contact with the substrate while rotating the gravure roll partially immersed in the coating liquid in the liquid receiving pan. A method of manufacturing a coating film to be transferred to the substrate, wherein the liquid receiving pan is formed so that a cross section has an arc shape, and the gravure roll rotates along the arc of the liquid receiving pan. A receiving pan and the gravure roll are arranged, and the coating liquid is poured into the liquid receiving pan from the upstream side in the rotation direction of the gravure roll with respect to the liquid receiving pan. .

The invention according to claim 2 is characterized in that the coating liquid has a shear viscosity of 1000 mPa · s to 20000 mPa · s when the shear rate is 1 [1 / s].
Furthermore, the invention according to claim 3 is characterized in that the liquid receiving pan has a double arc structure having a predetermined gap, and the coating liquid passes through the gap from the upstream edge in the rotation direction of the gravure roll. It is characterized by injecting liquid.

Further, in the invention according to claim 4, the liquid receiving pan and the gravure roll have a distance between an upstream side in the rotation direction of the gravure roll and the gravure roll, and a downstream side in the rotation direction of the gravure roll and the gravure roll. It is characterized by being arranged so as to be smaller than the distance from the roll.
Furthermore, in the invention according to claim 5, the distance between the upstream side in the rotation direction of the gravure roll and the gravure roll is less than 10 mm, and the downstream side in the rotation direction of the gravure roll and the gravure roll The distance is 10 mm or more and 100 mm or less.

  In the invention according to claim 6 of the present invention, the coating liquid adhered to the gravure roll is brought into contact with the substrate while rotating the gravure roll partially immersed in the coating liquid in the liquid receiving pan. In the coating apparatus for transferring to a substrate, the coating liquid is a coating liquid having a shear viscosity of 1000 mPa · s to 20000 mPa · s when the shear rate is 1 [1 / s], and the liquid receiver The pan has a double arc structure having a predetermined gap, and the liquid receiving pan has a liquid inlet formed on the inner edge of the liquid receiving pan on the upstream side in the rotational direction of the gravure roll. And a communication passage that is formed in the gap portion of the double arc structure and communicates with the liquid injection port and is supplied with the coating liquid.

  According to the present invention, the liquid receiving pan is formed so that the cross section thereof has an arc shape, and the coating liquid is injected into the liquid receiving pan from the upstream side in the rotation direction of the gravure roll. In the pan, the coating liquid flows along the arc-shaped inner surface of the liquid receiving pan. For this reason, since not only the flow of the coating liquid due to the rotation of the gravure roll but also the flow of the coating liquid can be generated in the portion along the inner surface of the liquid receiving pan, it is possible to suppress the occurrence of the staying portion of the coating liquid. it can. Therefore, even a liquid having a high viscosity particularly in a region where the shear rate of the coating liquid is low, it can be applied with a gravure coater while suppressing the distribution of the coating amount and managing the physical properties of the coating liquid.

It is a schematic block diagram which shows an example of the gravure coater to which this invention is applied. It is a block diagram which shows an example of the coating apparatus in this invention.

Embodiments of the present invention will be described below.
FIG. 1 is a schematic configuration diagram of a gravure coater to which the present invention is applied, and is a general gravure coater.
In FIG. 1, 2 is a base material unwinding part for continuously running the base material 1 wound up in a roll shape, 3 is a backup roll that supports the base material 1 so that it can continuously run, and 4 is for the base material 1 5 is a drying zone for drying the coating solution applied to the substrate 1, and 6 is a winding device for winding the substrate 1 after being dried in the drying zone 5 into a roll. Part.

The coating device 4 includes a liquid receiving pan 4a to which a coating liquid is supplied, a gravure roll 4b, a backup roll 4c arranged to face the gravure roll 4b, a doctor blade 4d, and the liquid receiving pan 4a. A liquid feed pump 4e for supplying the coating liquid and a liquid feed tank 4f for collecting the waste liquid from the liquid receiving pan 4a are provided.
The drying zone 5 is provided with a curing device such as a drying device for drying the coating solution applied to the substrate 1 and a potential radiation irradiation device for curing the coating film after drying, for example. Yes.

  When the coating liquid is supplied to the liquid receiving pan 4a, the coating liquid is lifted up by the gravure roll 4b, measured by the doctor blade 4d, and then transferred to the substrate 1. Further, a part of the coating liquid in the liquid receiving pan 4a is recovered from the waste liquid port (not shown) of the liquid receiving pan 4a to the liquid feeding tank 4f, and is sent again to the liquid receiving pan 4a as the coating liquid by the liquid feeding pump 4e. The coating liquid is circulated and utilized by a circulation system 4g formed by the liquid receiving pan 4a, the liquid feeding tank 4f, and the liquid feeding pump 4e.

Here, one in which the gravure roll 4b advances in the same direction with respect to the traveling direction of the substrate 1 is referred to as a direct method, and one that advances in the reverse direction is referred to as a reverse method. Further, there are a backup roll 4c installed at a position where it is pressed against the gravure roll 4b and a kiss system without the backup roll 4c, but the present invention is effective with any system.
Further, the present invention defines a method of supplying the coating liquid to the liquid receiving pan 4a, and the effect is not limited to the shape, material, installation position, and angle of the doctor blade 4d. The same applies to the gravure roll 4b, and the gravure roll 4b is not limited to the engraved pattern, roll diameter, material, or the like.

The supply of the coating liquid to the liquid receiving pan 4a is generally performed by installing a tube or the like connected to the liquid feeding pump 4e into the liquid receiving pan 4a and feeding the liquid through the tube by the liquid feeding pump 4e. It is done by.
However, in a liquid having a high viscosity in a region where the shear rate is low as used in the present invention, it is only in the vicinity of the coating liquid supply port for supplying the coating liquid into the liquid receiving pan 4a and in the vicinity of the rotating gravure roll. There is no fluidity of the coating liquid, and a staying portion of the coating liquid is generated.

As a result of earnest study, the present inventor can suppress the retention of the coating liquid by specifying the method of supplying the coating liquid to the liquid receiving pan 4a, and suppress the coating amount distribution (variation in coating amount). I found that I can do it.
That is, as shown in FIG. 2, the coating apparatus 4 according to the present invention has a liquid receiving pan 11 in which a gravure roll 12 is in contact with the substrate 1 in a liquid receiving pan 11 having a circular section perpendicular to the longitudinal direction. The coating liquid was supplied from the edge portion 11u side of the liquid receiving pan 11 on the side moving in the direction in contact with the coating liquid. Therefore, the flow of the coating liquid due to the rotation of the gravure roll 12 and the flow of the coating liquid due to the injection of the coating liquid occur, and the vicinity of the gravure roll 12 and the portion along the arcuate inner surface of the liquid receiving pan 11 Can cause the coating liquid to flow, and the coating liquid in the liquid receiving pan 11 can flow in a wider range. For this reason, the coating amount distribution could be suppressed even in a liquid having a high viscosity in a region where the shear rate of the coating liquid is low.

Hereinafter, the coating apparatus 4 to which the present invention is applied shown in FIG. 2 will be described.
FIG. 2 is a cross-sectional view showing an example of a coating apparatus 4 to which the present invention is applied, in which 11 is a liquid receiving pan to which a coating liquid is supplied, 12 is a gravure roll disposed facing the backup roll 13, 14 is a doctor blade, 15 is a waste liquid collection pan for collecting the coating liquid overflowed from the liquid receiving pan 11, 16 is a liquid feed tank for collecting the waste liquid collected by the waste liquid collection pan 15, and 17 is collected in the liquid feed tank 16. This is a liquid feed pump for feeding the waste liquid to the liquid receiving pan 11.

  As shown in FIG. 2, the liquid receiving pan 11 has a double arc structure in which a cross section perpendicular to the longitudinal direction has two arc-shaped members bonded together with a certain gap, and the inner member 21 is A liquid storage part 11a for storing the coating liquid is formed. The double arc structure liquid receiving pan 11 has an arc-shaped bottom surface along the arc of the gravure roll 12, and the arc forms a part of a concentric circle of the gravure roll 12. The liquid receiving pan 11 is formed to a length capable of immersing the entire longitudinal direction of the gravure roll 12 in the coating liquid in the liquid storage portion 11a.

  In the cross section of FIG. 2, the side facing the direction in which the portion of the gravure roll 12 that has been applied to the substrate 1 is in contact with the coating liquid in the liquid receiving pan 11, the upstream side in the rotation direction of the gravure roll 12, When the portion of the gravure roll 12 in contact with the coating liquid in the liquid receiving pan 11 moves in the direction in which the gravure roll 12 comes into contact with the base material 1 is the downstream side in the rotation direction of the gravure roll 12, Out of the two edges, a liquid injection port for injecting the coating liquid into the liquid storage part 11a of the liquid receiving pan 11 is applied to the inner member 21 of the edge 11u located on the upstream side in the rotation direction of the gravure roll 12. 31 is formed over the entire longitudinal direction of the inner member 21.

In addition, a buffer zone 32 that protrudes outward and has a substantially square cross section is formed over the entire length of the outer member 22 at the bottom of the outer member 22 of the liquid receiving pan 11.
Further, in the gap 23 formed between the inner member 21 and the outer member 22 between the edge 11d of the liquid receiving pan 11 located on the downstream side in the rotation direction of the gravure roll 12 and the buffer zone 32, A resin sheet 33 is embedded to prevent the coating liquid from entering the gap 23. The material of the resin sheet 33 may be selected in consideration of the resistance to the coating liquid to be used, and a fluorine resin or the like is preferable.

The buffer zone 32 is provided with a supply port (not shown), and the coating liquid is supplied to the buffer zone 32 from the supply port by the liquid feed pump 17 through the liquid feed tube 17a.
And the space | gap part formed with the inner side member 21 and the outer side member 22 between the buffer zone 32 and the edge 11u of the upstream of the rotation direction of the gravure roll 12 of the liquid receiving pan 11 is the buffer zone 32 and the liquid inlet. Thus, the coating liquid supplied to the buffer zone 32 by the liquid feed pump 17 is transmitted over the entire length in the buffer zone 32, whereby the coating liquid is applied over the entire width of the buffer zone 32. Is fed to the liquid injection port 31 through the communication path 24 and injected from the liquid injection port 31 to the liquid storage part 11 a of the liquid receiving pan 11. The coating liquid overflowed from the liquid receiving pan 11 is collected by the waste liquid collecting pan 15 and then sent to the liquid feeding tank 16.

  Here, since the liquid injection port 31 is provided in the vicinity of the edge 11u on the upstream side in the rotation direction of the gravure roll 12 of the liquid receiving pan 11, from the upstream side in the rotation direction of the gravure roll 12. The coating liquid is supplied to the liquid storage part 11 a of the receiving pan 11. For this reason, in the coating liquid in the liquid receiving pan 11, the flow of the coating liquid due to the rotation of the gravure roll 12 and the flow of the coating liquid due to the injection of the coating liquid from the liquid inlet 31 occur. The coating liquid and the part of the coating liquid along the inner surface of the liquid receiving pan 11 can be made to flow, and can be made to flow in a wider area. Therefore, the coating amount distribution can be suppressed by that amount even if the liquid has a high viscosity in the region where the shear rate of the coating liquid is low.

Further, the liquid receiving pan 11 and the gravure roll 12 have a position where the arc center of the double arc structure of the liquid receiving pan 11 is shifted to the downstream side in the rotation direction of the gravure roll 12 with respect to the rotation center of the gravure roll 12. It is arranged to become.
Specifically, in the cross section of the liquid receiving pan 11, the distance between the liquid receiving pan 11 and the gravure roll 12 in the liquid inlet 31 provided on the upstream edge 11 u in the rotation direction of the gravure roll 12 (hereinafter, The distance between the liquid receiving pan 11 and the gravure roll 12 at the downstream edge 11d in the rotation direction of the gravure roll 12 (hereinafter referred to as the downstream distance). ) Ld is preferably 10 mm or more and 100 mm or less.

  If the upstream distance Lu is less than 10 mm, the fluidity of the coating liquid can be obtained by the shearing force generated by the rotation of the gravure roll 12, so that the staying portion can be made substantially zero in the vicinity of the upstream edge portion 11u. However, when the distance between the liquid receiving pan 11 and the gravure roll 12 is set to be less than 10 mm over the entire double arc of the liquid receiving pan 11, that is, from the upstream edge 11u to the downstream edge 11d. The buffering effect due to the installation of the receiving pan 11 does not appear. The buffering effect means that the coating liquid leveled in the liquid receiving pan 11 is once applied to the gravure roll 12 by putting the coating liquid in the liquid receiving pan 11 (the leveling is not performed directly). The effect by what is done.

Therefore, by increasing the downstream distance Ld to 10 mm or more and 100 mm or less, it is possible to reduce the staying portion of the coating liquid while leaving a buffering effect. Furthermore, when the downstream distance Ld is increased by 100 mm or more, there is a possibility that the staying portion increases, which is not preferable.
In addition, the coating liquid is poured into the liquid storage part 11 a of the liquid receiving pan 11 by supplying the coating liquid to the buffer zone 32 provided at the bottom of the liquid receiving pan 11. If the pressure loss for uniformly spreading the coating liquid in the width direction of the liquid receiving pan 11 is obtained, the position where the coating liquid is supplied to the communication path 24, that is, the position of the buffer zone 32 is not limited. Considering maintainability such as the above, it is preferable to provide the buffer zone 32 at the bottom of the liquid receiving pan 11.

The distance of the gap between the inner member 21 and the outer member 22 of the liquid receiving pan 11 having the double arc structure should be set in a range that does not affect the pressure resistance of the liquid feeding pump 17, and is between 100 μm and 2 mm. Set to a value.
The opening width in the longitudinal direction of the liquid inlet 31 for injecting the liquid into the liquid storage part 11a of the liquid receiving pan 11 is the coating width of the gravure plate of the gravure roll 12 (the pattern of the plate is engraved) Approximately equal to (width) is preferred but need not be exactly equal. If it is narrower than the coating width, there may be problems such as non-uniformity in the vicinity of the end in the width direction, but if it is wider than the coating width, the difference between the coating width and the opening width is 100 mm. There is no problem if it is in the range.

  It is desirable that the amount of coating liquid supplied to the buffer zone 32 of the liquid receiving pan 11 by the liquid feeding pump 17 be as equal as possible to the coating amount to the gravure roll 12. As shown in FIG. 2, it is also possible to install a waste liquid collection pan 15 for receiving and appropriately discharging the overflowed coating liquid from the liquid receiving pan 11. However, at this time, from the viewpoint of management of physical properties of the coating liquid, a step of discarding the coating liquid may be provided instead of returning to the original supply system as shown in FIG. The supply amount should also be managed from the viewpoint of waste liquid property management.

  The width of the liquid receiving pan 11 is set such that the end portion thereof is positioned within 50 mm from the position of the end portion of the roll surface in the longitudinal direction of the gravure roll 12. If the length is longer than that, a staying portion is likely to be formed at the end of the liquid receiving pan 11, and the higher the viscosity in the region where the shear rate is low as used in the present invention, the greater the problem due to the staying. However, if the gravure roll 12 and the end portion of the liquid receiving pan 11 come into contact with each other, a foreign matter failure may occur. Therefore, the width of the liquid receiving pan 11 needs to be longer by 5 mm or more than the roll surface length.

The material constituting the liquid receiving pan 11 is generally a metal such as stainless steel or aluminum, and the shape accuracy is not so much required. It is also possible to coat the inner surface with a fluororesin in consideration of detergency.
As the coating solution, a coating solution having a shear viscosity of 1000 mPa · s to 20000 mPa · s when the shear rate is 1 [1 / s] can be applied.

  Moreover, in the said embodiment, although the case where the liquid injection port 31 was provided in the edge part of the upstream of the rotation direction of the gravure roll 12 was demonstrated, it is not necessarily restricted to an edge part, The rotation direction of the gravure roll 12 is demonstrated. Any position can be used as long as it is a position on the upstream side and can cause the coating liquid in the liquid receiving pan 11 to flow by liquid injection from the liquid injection port 31 and suppress the occurrence of the stagnant portion by this flow. It can be provided in the position.

  Moreover, in the said embodiment, although the liquid receiving pan 11 was formed in the double circular arc structure and liquid injection was demonstrated from the upstream edge part of the rotation direction of the gravure roll 12, it is not restricted to this. For example, a buffer zone may be provided at the upstream edge of the gravure roll 12 in the rotational direction, and the coating solution may be injected from the injection port provided in the buffer zone. Any configuration may be used as long as the coating liquid can be relayed from a region at the edge in the longitudinal direction of the pan 11 that is equivalent to the coating width of the gravure plate of the gravure roll 12.

  Moreover, although the case where the liquid receiving pan 11 is formed in a double arc structure having a constant gap has been described in the above embodiment, it is not always necessary to have a constant gap. It is only necessary that the communication path 24 from the buffer zone 32 to the liquid injection port 31 can be formed and the liquid injection can be performed uniformly in the longitudinal direction of the liquid injection port 31. The communication path 24 may be configured to have a double structure only up to the above.

Coating was carried out using a general gravure coater as shown in FIG. 1 and a gravure coater provided with a coating apparatus 4 shown in FIG. 2 to which the present invention was applied.
As the coating solution, a coating solution containing acrylic resin as a main component and methyl ethyl ketone as a solvent was used. By adding a crosslinking agent to the coating solution, the shear viscosity at a shear rate of 1 [1 / s] was 7000 [mPa · s]. The shear viscosity was measured using a rheometer RS75 manufactured by Harke.

When a general gravure coater is used, the evaporation of the solvent progresses with time, and a stagnant portion is formed at the end of the liquid receiving pan 11, so that the gravure roll 12 gradually prevents the coating liquid from being swirled. Detachment of the film surface was observed in the width direction.
On the other hand, when the gravure coater provided with the coating apparatus 4 according to the present invention was used, no staying portion was generated, and coating was possible without any particular problem. From the above, the effect of the present invention was confirmed.

  Even if the control of the coating liquid is severe, it can be applied without any problem with a gravure coater, and any product that is applied with a gravure coater is equally effective.

DESCRIPTION OF SYMBOLS 1 Base material 4 Coating apparatus 5 Drying zone 11 Liquid receiving pan 12 Gravure roll 13 Backup roll 14 Doctor blade 15 Waste liquid collection pan 16 Liquid feed tank 17 Liquid feed pump 24 Communication path 31 Liquid inlet 32 Buffer zone 33 Resin sheet

Claims (6)

A method for producing a coating film in which a coating liquid adhered to the gravure roll is transferred to the substrate by rotating the gravure roll partially immersed in the coating liquid in the liquid receiving pan while contacting the substrate. And
The liquid receiving pan is formed so that a cross-section is an arc shape, and the liquid receiving pan and the gravure roll are arranged so that the gravure roll rotates along the arc of the liquid receiving pan,
A method for producing a coating film, characterized in that the coating liquid is poured into the liquid receiving pan from the upstream side in the rotational direction of the gravure roll.   The method for producing a coating film according to claim 1, wherein the coating liquid has a shear viscosity of 1000 mPa · s to 20000 mPa · s when the shear rate is 1 [1 / s]. The liquid receiving pan has a double arc structure with a predetermined gap,
3. The method for producing a coating film according to claim 1, wherein the coating liquid is injected from the upstream edge portion in the rotation direction of the gravure roll through the gap. The liquid pan and the gravure roll are:
The distance between the upstream side in the rotation direction of the gravure roll and the gravure roll is arranged to be smaller than the distance between the downstream side in the rotation direction of the gravure roll and the gravure roll. The method for producing a coating film according to any one of claims 1 to 3.   The distance between the upstream side in the rotation direction of the gravure roll and the gravure roll is less than 10 mm, and the distance between the downstream side in the rotation direction of the gravure roll and the gravure roll is from 10 mm to 100 mm. The manufacturing method of the coating film of Claim 3. In the coating apparatus for transferring the coating liquid attached to the gravure roll to the substrate while rotating the gravure roll partly immersed in the coating liquid in the liquid receiving pan and contacting the substrate,
The coating solution is a coating solution having a shear viscosity of 1000 mPa · s to 20000 mPa · s at a shear rate of 1 [1 / s],
The liquid receiving pan has a double arc structure with a predetermined gap,
And the liquid receiving pan, a liquid injection port formed on the inner edge of the upstream side of the rotation direction of the gravure roll of the liquid receiving pan,
A coating apparatus, comprising: a communication path formed in the gap portion of the double arc structure and communicating with the liquid injection port and to which the coating liquid is supplied.

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