JP2000117174A - Applicator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable good application without film breakage even under high tension, to make manufacture easy even when an apparatus is wide, and to enable uniform application in the width direction. SOLUTION: In an applicator, a film 6 traveling under a prescribed tension is supported by a pair of support rolls 7, 8 separated at a prescribed distance, a die 1 is pressed on the surface of the film 6 in its intermediate part, and a coating solution is pushed out from the slit 4 of the die 1 to be applied continuously on the film 6. In this process, an upstream side lip surface 2 and downstream side lip surfaces 3a, 3b has plane parts of a prescribed length connected with the slit 4 substantially in the same plane, the downstream side lip surfaces 3a, 3b comprise the plane parts and a retreating plane part 3b which retreats at a prescribed angle from the film 6 following the plane part.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a coating apparatus for continuously forming a coating film on a film using a die. More specifically, it can be applied to high-speed off-line coating on running film or in-line coating in the film manufacturing process,
The present invention relates to a coating apparatus capable of forming a coating film having a uniform and good appearance even under high tension.

[0002]

2. Description of the Related Art A film such as a plastic film is easily adhered, lubricated, gas barrier, dampproof, antistatic,
Coating is generally performed for the purpose of imparting functions such as ink receptivity. As a coater used for this, for example, a gravure coater, a kiss roll coater, a curtain coater, a knife coater, an extrusion die coater and the like are known. Among them, the extrusion die coater is excellent in that a uniform and good coating film can be obtained even in a high-speed region, and has recently been put to practical use.

[0003] As shown in FIG.
The tip of the die is composed of an upstream lip surface 2 and a downstream lip surface 3, and has a feature that the coating liquid extruded from the slit 4 is applied while being measured in a minute gap between the lip surface and the film. In order to eliminate the influence of the vibration of the backup roll, a die coating method in which the back surface of the film is not supported by the backup roll or the like has been adopted. In this case, the film pressure and the film reaction force generated in the above-mentioned gap are balanced. There is a feature of applying while floating.

Although such a die coater can perform high-speed coating, it has several problems. For example, a problem that a streak defect occurs due to a foreign substance attached to a film or an agglomerate in a coating liquid being trapped on the downstream lip surface 3,
In addition, there is a problem that the upstream lip surface 2 comes into contact with the film 6 to cause film shaving, and conversely, if the gap between the upstream lip surface and the film is too wide, the accompanying air disturbs the coating film.

In order to solve these problems, Japanese Patent Laid-Open Publication No. Hei.
Japanese Patent Application Publication No. 184072 discloses a coating apparatus shown in FIG. That is, the length L of the upstream lip surface is set to 1 mm or less,
The downstream lip surface 3 is a curved surface and a part thereof is the upstream lip surface 2
It is characterized by being more prominent.

[0006]

However, in this prior art, the upstream edge B of the downstream lip surface 3 is lower than the upstream lip surface 2 as can be seen from FIG.
The gap between the film and the film 6 is wider than other gaps.
As a result, the liquid pressure was reduced near the edge B, and a sufficient film floating amount could not be obtained, and the contact with the upstream lip surface 2 was increased, and film abrasion sometimes occurred. In particular, in the in-line coating during the film manufacturing process involving stretching of the film, the film tension is 2 to 20 compared to the offline process.
Twice as high. Therefore, the probability that the upstream lip surface 2 would directly contact the film 6 when the die tip was pressed against the film was high, and the damage at the time of contact was very large.

Further, since a part of the downstream lip surface 3 protrudes from the upstream lip surface 2, a relative angle is generated between the entrance path of the film 6 and the upstream lip surface 2, so that the contact of the film 6 is upstream. Concentration on the upstream edge A of the side lip surface 2 was also one of the factors that promoted the film scraping. It is conceivable to change the retreat angle of the upstream lip surface 2 in accordance with the approach path of the film 6, but it is necessary to use a plurality of dies with different retreat angles depending on the application conditions (film tension and application speed), which is not preferable. .

In the above-mentioned publication, the problem that the accompanying air disturbs the coating film is taken up as a problem contradictory to film shaving. This is considered to be attributable to the fact that this becomes apparent under a somewhat high-speed condition and that the accompanying air is more likely to be mixed into the coating surface due to the floating of the film more than necessary due to an increase in the liquid pressure. In the case of a high tension of not less than / m, this phenomenon is not apparent because the floating of the film is appropriately suppressed. Therefore, it was found that the problem of film scraping was more important.

On the other hand, in order to obtain a uniform coating film, the lip surfaces on the upstream side and the downstream side are required to have extremely high finishing accuracy, but the processing of the downstream lip surface 3 which is a curved surface as shown in FIG. It is very difficult to finish with the required precision. In particular, when a die having a coating width of 1.5 m or more is to be manufactured, the required accuracy must be reduced, and the uniformity of the coated surface may be adversely affected. In addition, as the die is used for a long period of time, the lip surface is scratched and needs to be refinished. At that time, since the curved lip requires very high technology to reproduce the same performance, an increase in cost and an increase in delivery time are inevitable.

Further, even if the upstream lip surface 2 is a flat surface whose accuracy can be easily controlled as shown in FIG. 4, if the downstream lip surface 3 is a curved surface, each lip surface must be individually polished. It is very difficult to maintain the same finishing accuracy on the lip surface. As a result, in particular, in the case of a long die, the step at the exit of the slit 4 varies in the width direction of the die, so that a uniform coating cannot be performed in the width direction, or the finish is not reproducible even when a spare die is held. There was a problem.

Therefore, the present invention solves the above-mentioned problems, that is, it enables a good coating without abrasion of the film even under a high tension, and is easy to manufacture even with a wide-width facility, and provides a uniform coating in the width direction. It is an object of the present invention to provide a coating device that enables the application.

[0012]

The present invention has the following arrangement to attain the above object. That is, the present invention
A film running under a predetermined tension is supported by a pair of support rolls separated by a predetermined distance, a die is pressed against the film surface in the middle, and the coating liquid is extruded from the slit of the die to be continuously applied on the film. In the coating device, the lip surface of the die is constituted by a combination of planes, and the upstream lip surface and the downstream lip surface have a plane portion of a predetermined length connected to a slit substantially in the same plane, and the downstream side The coating apparatus is characterized in that the lip surface comprises the flat portion and a receding flat portion that retreats at a predetermined receding angle following the flat portion.

According to the present invention, with the above-described structure, a portion of a predetermined length following the slit at the most upstream portion of the downstream lip surface of the die is flush with the upstream lip surface and has no protruding portion. There is no stress concentration on the film at the edge on the upstream side of the lip surface, which prevents film shaving, and because the lip surface is composed of a combination of flat surfaces, it is easy to manufacture and maintain accurate surfaces. The above-mentioned object is achieved.

In the present invention, the length of the flat portion of the upstream lip surface along the running direction of the film is 0.5 mm.
It is preferable that the thickness be 3 mm or less from the viewpoint of stable application. It is also preferable that the length of the flat portion of the downstream lip surface along the film running direction be 1 mm or more and 12 mm or less.

[0015] Further, the receding flat portion of the downstream lip surface is the first lip surface.
Consisting of a first receding flat portion having a receding angle and a second receding flat portion having a second receding angle larger than the first receding angle continuous with the first receding angle, It is preferable from the viewpoint of uniformity and the like.

The present invention described above has a remarkable effect of realizing stable coating, which has been difficult with the prior art, in a film being produced in a film forming process under high tension. Hereinafter, the present invention will be described in more detail with reference to the drawings.

[0017]

FIG. 1 is an explanatory diagram of one embodiment of the present invention. FIG. 2 is an explanatory diagram of the configuration of the lip surface of the die of the embodiment, and FIG. 3 is an explanatory diagram of another embodiment of the lip surface of the die.

In the drawing, 1 is a die, 2 is an upstream lip surface, 3a is a downstream lip surface flat portion, 3b and 3c are downstream lip surface receding flat portions, 4 is a slit, and 5 is a manifold. , 6 are films running at a predetermined speed, 7 and 8
Reference numeral denotes a support roll for supporting the film 6 upstream and downstream of the die 1. L indicates the length of the upstream lip surface 2 in the film running direction, F indicates the running direction of the film 6, and X indicates a plane including the upstream lip surface 2.

In this embodiment, the coating film is formed by supplying a coating liquid from a coating liquid supply system (not shown) to the manifold 5 of the die 1 and extruding the coating liquid from the slit 4 communicating with the manifold 5 to form the downstream lip surfaces 3a and 3b. The coating is performed by applying a coating liquid on the film 6 while measuring at a minute gap between the film 6 and the film 6.

In this embodiment, a pair of support rolls 7
Reference numeral 8 denotes a position which is separated from the die 1 by a predetermined distance, specifically, a distance which can substantially ignore the influence of the rotational vibration of these rolls on the coating on the die 1. This allows
It is possible to prevent the rotational vibration of the support rolls 7 and 8 from adversely affecting the formation of the coating film. In this configuration, the die 1
Since there is no backup roll on the opposite side, there is no problem such as rotational vibration of the backup roll.

Incidentally, the configuration of the lip surface of the die 1 is as shown in FIG. That is, the upstream lip surface 2 connected to the slit and the flat portion 3a of the downstream lip surface are formed of a flat portion having a predetermined length substantially in the same plane X, and the downstream lip surface is followed by the flat portion 3a. It is composed of a receding flat portion 3b receding from the plane X at a predetermined receding angle, and the lip surface is a combination of only flat surfaces. Note that FIG.
The first and second receding flat portions 3b and 3c having different receding angles are used as the receding flat portions on the downstream lip surface.

If the length L (mm) of the upstream lip surface 2 is too long in the die shown in FIGS.
When the film is too short, the coating liquid overflows from the upstream lip surface 2 if the length is too short.
≦ L ≦ 3 is preferable, and 1 ≦ L ≦ 2 is more preferable. Naturally, the shape further upstream from this surface is retracted so as not to contact the film.

On the other hand, the lip surface on the downstream side in the die shown in FIGS. 2 and 3 is composed of a plurality of planes as described above. To prevent it from narrowing down. Thus, the streak defect can be eliminated by preventing the foreign matter or the like from being caught. Of these downstream lip surfaces, the most upstream flat portion 3
The length a is preferably 1 to 12 mm. Under this condition, sufficient hydraulic pressure is generated to prevent direct contact between the film 6 and the upstream lip surface 2, but more preferably 2 to 7 mm.

The plane portion 3a is in the plane X including the upstream lip surface 2 as described above. By doing so, both lips can be integrally polished and finished with high accuracy while maintaining the same accuracy, so that a wide die can be manufactured.
Further, the downstream lip surface other than the flat portion 3a is constituted by a single receding flat portion 3b as shown in FIG.
As shown in the figure, the one formed of two receding flat portions 3b and 3c can be exemplified. Increasing the number of the receding flat portions is disadvantageous in terms of manufacturing, but can alleviate the stress concentration on the film. It is preferable that the receding angle, the length, and the number of surfaces of the receding flat portion are appropriately selected by a test operation or the like.

The film 6 is not particularly limited depending on the material, but is preferably a plastic film, such as a polyolefin film (for example, a polyethylene film or a polypropylene film), a polyester film (for example, a polyethylene terephthalate film, a polyethylene film).
2,6-naphthalate film, etc.) and polyamide film (for example, polyetherketone film etc.). The traveling speed is preferably 5 to 1000 m / min.
0 to 500 m / min is preferred. The thickness is 5 to 800
μm is preferable, and 10 to 200 μm is more preferable.
The tension is preferably 30 to 2000 kg / m.

The coating liquid used in the present invention has functional properties such as adhesion (including easy adhesion and heat sealability), easy slip (running), antistatic property, conductivity and abrasion resistance on the film surface. , Abrasion resistance, weather resistance, mold release properties, chemical resistance (including water resistance, solvent resistance), easy printability, flowability, antifouling properties, writing properties,
Any coating solution may be used as long as it is a surface processing coating liquid that imparts light-shielding properties, waterproof properties, gas barrier properties, and the like. As these coating liquids, those conventionally known or used can be used. The viscosity of the coating liquid is 1 to 500
Centipoise (cP), more preferably 1.1 to 20 cP.
Hereinafter, an example of film formation according to this example will be described.

[0027]

[Film Forming Example 1] Coating was performed using the coating apparatus shown in FIG. 1 and the die shown in FIG. Film 6 has a speed of 200 m
/ Min, a uniaxially stretched polyethylene terephthalate film having a thickness of 16 μm. Die 1 has an application width of 800 m
m, the length L of the upstream lip was 1 mm, the length of the flat portion 3a of the downstream lip was 5 mm, the receding angle was 2 degrees, the length was 2 mm, and the slit gap was 100 μm. . As the coating liquid, a water-based emulsion coating liquid having a viscosity of 2 cP was used and supplied to the die 1 so that the wet film thickness became 4 μm. Coating was started under these coating conditions, and thereafter, coating was continuously performed for about 8 hours. During this time, it was found that there was no streak defect and no scraping of the film, and good coating was possible even at high speed. At the same time, when the wet film thickness in the width direction was measured, it was found that a uniform coating film was formed in the width direction. It was confirmed that the finishing accuracy of the lip surface was good even with a wide die.

[0028]

[Film forming example 2] The coating was performed under the same conditions as in film forming example 1 except that the speed of the film 6 was changed to 15 m / min and the thickness was changed to 800 µm. When the film tension was measured, it was 2000
Although the tension was as high as kg / m, good application was possible as in Example 1 for forming a film.

[0029]

[Comparative Example 1] Using the conventional die shown in FIG. 4 (upstream lip length is 1 mm, downstream lip length is 5 mm, the cross section is a circular arc having a radius of 10 mm, and the slit gap is 100 μm), the coating width is adjusted. Coating was performed under the same coating conditions and film forming conditions as in Example 2 except that the thickness was 800 mm. As a result, intense film scraping occurred, and scratches called scratches occurred frequently on the film surface.

[0030]

According to the present invention, it is possible to form a coating film having a uniform and good appearance even with a high tension and wide equipment with a simple structure in which the lip surface of the die is a combination of specific planes. The device is realized. And it is easy to manufacture with a planar configuration, and equipment and maintenance costs are low. Further, it can be applied to in-line coating in a film manufacturing process.
As described above, the present invention greatly contributes to improvement of productivity, quality improvement, cost reduction, and the like of a functional film in which functional films are laminated.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a configuration of one embodiment of the present invention.

FIG. 2 is an explanatory diagram of a configuration of a lip surface of a die of the embodiment of FIG. 1;

FIG. 3 is an explanatory diagram of a configuration of another embodiment of a lip surface of a die.

FIG. 4 is an explanatory diagram of a configuration of a lip surface of a conventional die.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Die 2 Upstream lip surface 3 Downstream lip surface 3a Downstream lip surface flat portion 3b, 3c Downstream lip surface receding flat portion 4 Slit 5 Manifold 6 Film 7 Upstream support roll 8 Downstream support roll B The most upstream edge of the downstream lip L The length of the upstream lip surface F The running direction of the film X A plane including the upstream lip surface

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Shinji Numazawa 3-37-19 Koyama, Sagamihara-shi, Kanagawa F-term in the Sagamihara Research Center, Teijin Limited 4F041 AA00 AA12 CA02 CA12

Claims (5)

[Claims] 1. A film running under a predetermined tension is supported by a pair of support rolls spaced at a predetermined distance, a die is pressed against the film surface at an intermediate portion thereof, and a coating liquid is extruded from a slit of the die to form a film on the film. In a coating apparatus that continuously applies the lip surface of the die, the lip surface of the die is constituted by a combination of flat surfaces, and the upstream lip surface and the downstream lip surface have a flat portion having a predetermined length connected to a slit substantially in the same plane. The coating apparatus, wherein the downstream lip surface comprises the flat portion and a receding flat portion that retreats at a predetermined receding angle following the flat portion. 2. The coating apparatus according to claim 1, wherein the length of the flat portion of the upstream lip surface along the running direction of the film is 0.5 mm or more and 3 mm or less. 3. The coating method according to claim 1, wherein the length of the flat portion of the downstream lip surface along the film running direction is 1 mm or more and 12 mm or less. 4. The retreating flat portion of the downstream lip surface is the first lip surface.
The coating apparatus according to any one of claims 1 to 3, comprising a first receding flat portion having a receding angle and a second receding flat portion having a second receding angle larger than the first receding angle continuous with the first receding flat portion. 5. The film coating apparatus according to claim 1, wherein the film is a film being produced in a film forming process.