JPH10235269A - Coating applicator and coating application - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the deflection of a metering bar within a permissible range by constituting a metering unit scraping away the excess supplied coating liquid by freely rotatably circumscribing and supplying the metering bar with two backup rollers and specifying the distance between the centers of rotation of these backup rollers. SOLUTION: The metering unit of the coating applicator including the metering unit for scraping only the excess coating liquid in such a manner that the coating liquid 2 applied on the surface of a web 3 attains a regulated thickness has the metering bar 1 extending in the transverse direction of the web 3. The metering unit has a pair of the backup rollers 4 by which the metering bar 1 is circumscribed and supported. At this time, the distance L between the centers of rotation of the respective backup rollers 4 is so set as to be made smaller than the max. outside diameter D of these rollers 4. As a result, the spacing H between the web 3 and the backup rollers 4 is adequately assured and the exact and precise position adjustment of covers 7, 8 is made possible.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coating apparatus and a coating method for applying a coating solution having a uniform thickness to a web running in a predetermined direction.

[0002]

2. Description of the Related Art In general, in order to uniformly apply a coating solution to a web surface with a predetermined thickness, a metering bar method is often used in which an excessive amount of a coating solution is applied, then scraped off and accurately measured. Have been. FIG. 3 is a schematic sectional view showing a metaling section of the above-mentioned metaling system which is a general coating apparatus. The metaling bar 1 is usually a metal bar (not shown) in which a wire is densely wound on an outer peripheral surface thereof, and is generally supported at both ends.

[0003] However, since the coating width in the width direction of the web 3 is considerably larger than the diameter of the metalling bar 1, the metalling bar 1 depends on the tension of the web 3 and the weight of the metalling bar 1 itself. Deflection occurs. If the bending of the metering bar 1 occurs, the coating liquid 2 cannot be uniformly scraped off in the width direction of the web 3. As a result, a coating film having a uniform thickness on the surface of the web 3 cannot be obtained.

When the web 3 is run at a high speed, the surface of the coating liquid 2 becomes unstable, and uneven coating occurs in the width direction of the web 3. The coating unevenness is a difference in the thickness of the coating liquid 2 on the surface of the web 3 and appears as a fine stripe-shaped defect.
To eliminate this coating streak defect, a metering bar 1
Conventionally, the diameter of the metal ring bar 1 has been reduced. However, if the diameter of the metalling bar 1 is reduced, the amount of deflection increases. Therefore, it is necessary to support the metaling bar 1 so that the bending of the small-diameter metaling bar 1 is prevented by some method.

As one of the means, Japanese Patent Publication No. 6-491
No. 69 discloses a method. FIG. 4 is a schematic sectional view of a metering section of the coating apparatus.

In FIG. 4, 1 is a metering bar,
Reference numeral 2 denotes a coating liquid, and reference numeral 3 denotes a web running at high speed. The metering bar 1 is supported by a backup roller 4 over the entire outer circumference. FIG. 5 is a schematic diagram of the backup roller. The backup roller 4 includes a groove 5 and a flange 6, the axis of which is parallel to the axis of the metering bar 1.

[0007] By constructing the metering portion in this manner, the web 3 can be prevented while preventing the bending of the metering bar 1.
Only the surplus coating liquid 2a of the coating liquid 2 applied to the coating surface of the above is guided through the metalling bar 1 into the groove 5 of the backup roller 4 and discharged.

However, when the web 3 runs at a high speed, the excess coating liquid 2b remaining on the outer peripheral surface of the brim portion 6 is scattered by the centrifugal force of the backup roller 4, and the coating surface which has been beautifully coated to a specified thickness is used. , And as a result, there is a problem that the coating quality is significantly reduced.

According to the publication, as a method for preventing the scattering of the surplus coating liquid, a coating liquid intrusion prevention cover for preventing the surplus coating liquid 2a from adhering to the backup roller 4 is provided upstream of the metering bar 1. 7, a coating liquid scatter to prevent the surplus coating liquid 2 b adhering to the backup roller 4 from adhering to the web 3 even on the downstream side of the metering bar 1 even if it is scattered by the centrifugal force of the backup roller 4. A prevention cover 8 is provided.

However, also in this method, when the diameter of the metering bar 1 is further reduced, the gap between the web 3 and the backup roller 4 is reduced, and the covers 7, 8
There is a problem that it is substantially difficult to take a structure that makes the metalling bar as close to the metering bar 1 as possible. As a result, since the diameter of the metalling bar 1 cannot be reduced, the coating liquid cannot be scraped off with a uniform film thickness on a web running at a high speed and wide, and a high-quality product cannot be obtained.

[0011]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned drawbacks of the prior art, to prevent the coating liquid from entering or scattering while keeping the deflection of the metalling bar within an allowable range, and to prevent uneven coating and coating. While preventing the occurrence of defects such as streaks,
An object of the present invention is to provide a coating apparatus, a coating method, and a method for producing a thermoplastic resin film using the coating apparatus, which can apply a coating liquid with a uniform thickness on a wide web surface running at high speed.

[0012]

Means of the present invention for achieving the above object are as follows: (1) a means for supplying an excess coating liquid to a running web surface; and a means for scraping an excessively supplied coating liquid. In a coating apparatus having a dropping metaling bar, the bar is rotatably circumscribed by at least two backup rollers, and the distance between the rotation centers of the backup rollers is smaller than the maximum outer diameter of the backup roller itself. A coating apparatus comprising the metering unit configured as described above.

(2) The coating apparatus according to the above (1), wherein a plurality of sets of the metering units are provided in the web running direction.

(3) The metering unit located at a distance farther than the means for supplying the coating liquid is different from the metering unit located at a shorter distance than the metering unit in the metaling bar of the metering unit. The same or smaller outer diameter, the same or smaller amount of coating liquid passing through the bar, the same or smaller backup roller outer diameter, and the same or more backup rollers The coating apparatus according to claim 2, wherein at least one of the following is satisfied.

(4) The coating apparatus according to any one of (1) to (3) above, wherein the backup roller is configured so that the maximum deflection amount of the metalling bar is 500 μm or less.

(5) A coating method using the coating apparatus according to any one of the above (1) to (4).

(6) extruding a thermoplastic resin from an extruder,
This is a method of producing a thermoplastic resin film by discharging in the form of a sheet with a die, stretching in the longitudinal direction, stretching in the horizontal direction, and winding the film.
A method for producing a thermoplastic resin film, characterized by applying a coating liquid to a film using the coating apparatus according to any one of (1) to (4).

[0018]

BRIEF DESCRIPTION OF THE DRAWINGS FIG.

The web in the present invention can be applied to a thermoplastic resin film, paper, leather, nonwoven fabric, knitted fabric and the like.

The coating apparatus according to the present invention comprises a means for applying the coating liquid 2 slightly over the specified coating amount on the surface of the web 3 as in the conventional example, and a method for applying excess coating liquid to the specified thickness. A metering unit for scraping and measuring only the coating liquid is provided.

FIG. 1 is a schematic sectional view showing an embodiment of the metering unit of the present invention. FIG. 2 is a schematic plan view of FIG.

Metalling bar 1 as a metalling means
Extends in the width direction of the web 3 and is not particularly limited as long as the purpose is to scrape off the excess coating solution 2a from the coating solution 2 applied to the web 3 by a coating unit (not shown). . Specifically, a small-diameter steel roller having a diameter of about 3 to 30 mm is preferably applied, and is adjusted to a position where the coating liquid 2 is scraped off so as to be close to the surface of the web 3 and have a predetermined thickness. ing. The metering bar 1
0.01-1mm in diameter to improve the weighing function on the outer circumference
About 1 wire wound, depth 0.001
Preferably, a spiral groove having a pitch of 0.1 mm and a pitch of 0.01 to 0.1 mm is provided. .

In the present invention, the rotation direction of the metering bar 1 is usually rotated in the same direction as the running direction of the web 3 in order to prevent the surface of the web 3 from being scratched.

The peripheral speed of the metering bar 1 is as follows.
The running speed of the web 3 is affected by the conditions of the coating solution 2, such as the viscosity and temperature of the coating solution, the running speed of the web 3, the conditions of the object to be coated such as surface roughness, and the coating conditions such as coating accuracy. -
The content is preferably set to 10% to + 10%. The reason is that if the metalling bar 1 is rotated in the same direction as the traveling direction of the web 3 and within the above-mentioned speed range, the metalling bar 1 is rotated.
This is because not only does the above-mentioned scratching not occur due to the relative speed difference between the web and the web 3 becoming small, but also the breaking of the wire and the wear of the metaling bar 1 can be prevented. Here, the same direction refers to a rotation direction of the metaling bar 1 with respect to the web 3 at a contact point between the web 3 and the metaling bar 1. As long as the metering bar 1 and the backup roller 4 are within the above-mentioned speed range, they may rotate freely or may be driven positively.

The backup roller 4 prevents the metalling bar 1 from bending in the opposite direction to the web 3 due to the force from the web 3 and the weight of the metering bar 1 itself. The axis is provided parallel to the axis of the metering bar 1. The material of the backup roller 4 is not particularly limited, and any material in which a bearing or the like is incorporated inside is more preferable. This backup roller 4 is, like the metering bar 1, used for the web 3
May be provided continuously in the width direction of
It may be provided discontinuously. The number may be a minimum number that can prevent the bending of the metalling bar 1 to a practically acceptable level. Specifically, it is preferable that the deflection of the metalling bar 1 is configured to be 500 μm or less.

It is preferable that the backup roller 4 is rotated at a speed substantially equal to the peripheral speed of the metering bar 1. If there is too much difference in the relative speed between the two, the metering bar 1 and the backup roller 4 will be worn, and wear debris will adhere to the coating surface of the web 3 to cause coating defects.

Such a metering unit is provided on a web 3
A plurality of sets exist in the traveling direction, and a metalling unit located farther from the supply means of the coating liquid 2 satisfies at least one of the following requirements with respect to a metalling unit located closer. More preferably, by simultaneously satisfying a plurality of requirements, the accuracy of measurement is further improved, and a more preferable product is obtained. In order to improve the measurement accuracy, the diameter of the metering bar 1 is the same or smaller, or, similarly, to improve the measurement accuracy, the amount of the coating liquid 2 passing through the bar 1 is the same or smaller, or In order to secure a gap between the web 3 and the backup roller 4, the maximum outer diameter of the backup roller 4 should be the same or smaller, or the backup roller 4 should be reduced to minimize the bending of the metering bar 1. Are configured to be the same or more.

According to the present invention, as shown in FIGS. 1 and 2, in order to constitute the coating liquid intrusion prevention cover 7 and the coating liquid scattering prevention cover 8 in the above-described metering unit, as shown in FIGS. To two backup rollers 4
When it is intended to circumscribe the backup roller 4, the distance L between the rotation centers of the backup rollers 4 is configured to be smaller than the maximum outer diameter D of the backup roller 4. That is, as compared with the conventional example, the gap H between the web 3 and the backup roller 4 is ensured by forming a configuration in which the generally facing brim portion 6 is staggered and close to the side opposite to the web 3 of the metering bar 1, It becomes easy to adjust the positions of the covers 7 and 8 accurately and precisely, which could not be done in the conventional example.

Further, by using the metering unit,
Since the metalling bar 1, the backup roller 4, the coating liquid intrusion prevention cover 7, and the coating liquid scattering prevention cover 8 are unitized, it is very easy to replace the metaling bar 1 and to remove the metaling member at the time of cleaning. Yes, workability is improved.

[0030]

An embodiment of the present invention will be described below.

In FIG. 1 and FIG. 2, reference numeral 3 denotes a web made of a polyester film having a width of 1000 mm running in the direction of the arrow. One side of the web is provided by a kiss roller (not shown) installed upstream of the metering bar 1. Coating liquid 2
Is applied.

1 has a diameter of 20 mm and a linear shape of the wire of 0.
This is a stainless steel metering bar with a length of 15 mm and a length of 1200 mm. 4 has a diameter D of 15 mm and a width of 10 mm
And supports the metering bar 1 from the side opposite to the web 3. The backup roller 4 has a length of 12 in the longitudinal direction of the metering bar 1.
A pair is installed. A gap H between the backup roller 4 and the web 3 is 9 mm. Reference numeral 7 denotes a synthetic resin coating liquid intrusion prevention cover, and reference numeral 8 denotes a synthetic resin coating liquid scattering prevention cover. Even if they do not come into contact with the metalling bar 1, they are attached almost without gaps.

An aqueous solution of a low-melting polyester having a viscosity of 10 cp was applied to the thus configured metering unit with a kiss roller (not shown) at an application thickness of 50 μm and a running speed of 200 m / min. Most of the surplus coating liquid 2a scraped off at 1 was discharged along the upper surface of the cover 7 without entering the gap between the metering bar 1 and the coating liquid intrusion prevention cover 7. Also, a part of the surplus coating liquid 2b is scattered by the centrifugal force of the backup roller 4, but the coating liquid scattering prevention cover 8
A beautiful product weighed to a thickness of 10 μm was obtained without adhering to the coating film after weighing.

[0034]

As described above, according to the coating apparatus and the coating method of the present invention, even if the diameter of the metaling bar is extremely small, it is possible to support the metalling bar so as to keep the deflection of the metaling bar within an allowable range. Furthermore, it is easy to take measures against the scattering of excess coating liquid, preventing the occurrence of defects such as coating unevenness and coating streaks,
It is possible to apply a thin film on a very wide web surface at a high speed and uniformly with a stable film thickness, and to obtain a high quality web.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view of an example of an embodiment of a metering unit section of a coating apparatus according to the present invention.

FIG. 2 is a schematic plan view of the coating apparatus according to the present invention shown in FIG.

FIG. 3 is a schematic sectional view of a metering section of a general coating apparatus.

FIG. 4 is a schematic cross-sectional view of a metering section showing a conventional coating apparatus.

FIG. 5 is a schematic view of a backup roller constituting a conventional coating apparatus.

[Explanation of symbols]

 1: Metalling bar 2, 2a, 2b: Coating liquid 3: Web 4: Backup roller 5: Backup roller groove 6: Backup roller brim 7: Coating liquid intrusion prevention cover 8: Coating liquid scattering prevention cover L: Backup Distance between roller rotation centers D: Maximum outer diameter of backup roller H: Clearance between web and backup roller

Claims (6)

[Claims] In a coating apparatus having means for supplying an excess coating solution to a running web surface and a metaling bar for scraping off the excess coating solution, the bar is provided by at least two backup rollers. An application device, comprising a metering unit rotatably circumscribing and having a configuration in which the distance between the rotation centers of the backup rollers is smaller than the maximum outer diameter of the backup rollers themselves. 2. The coating apparatus according to claim 1, wherein a plurality of sets of said metering units are provided in a web running direction. 3. The metering unit located farther than the means for supplying the coating liquid is located outside the metering bar of the metering unit with respect to the metering unit located closer than the metering unit. The same or smaller diameter, the same or smaller amount of coating liquid passing through the bar, the same or smaller backup roller outer diameter, and the same or more backup rollers 3. The coating apparatus according to claim 2, wherein at least one is satisfied. 4. The method according to claim 1, wherein the maximum deflection amount of the metalling bar is 50.
The coating device according to any one of claims 1 to 3, wherein the backup roller is configured to have a thickness of 0 µm or less. 5. A coating method using the coating device according to claim 1. 6. A method for producing a thermoplastic resin film by extruding a thermoplastic resin from an extruder, discharging in a sheet shape by a die, stretching in a longitudinal direction, stretching in a lateral direction, and winding. 2. The method according to claim 1, wherein the stretching is performed between the longitudinal stretching and the transverse stretching.
A method for producing a thermoplastic resin film, comprising applying a coating liquid to a film using the coating device according to any one of claims 1 to 4.