JPH05177159A - Top coating bar process - Google Patents

Abstract

PURPOSE:To obtain a top coating bar process to apply a low viscosity application liquid thinly to the top of a film running continuously in a horizontal direction. CONSTITUTION:An application device 12, equipped with a metalling bar 5 supported by a bar holder part 6' near the outlet of a die part 11', is used, when a 1 to 10cps viscosity application liquid 2 is applied to the top of a film 4 which runs continuously in a horizontal direction so that the wet applied thickness is 3 to 15mum. In addition, this application device 12 is arranged in such a manner that the metalling bar 5 comes in contact with the top of the film 4, and besides, is located on the running side of the film 4 from the outlet of the die part 11'. Further, the application liquid 2 is supplied from the outlet of the die part 11' so that a liquid reservor 10 for the application liquid is formed right before a part where the metalling bar 5 comes in contact with the film 4, and the applied amount is measured using the metalling bar 5 for coating process.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a top coating bar coating method, and more particularly to a top coating bar coating method capable of coating a thin film of a low-viscosity coating liquid on the top surface of a film continuously running in the horizontal direction. It is a thing.

[0002]

2. Description of the Related Art Conventionally, an antistatic agent is attached to the surface of a film,
When forming a coating film such as an easy-adhesion lacquer, a low-viscosity coating liquid having a viscosity of 1 to 10 cps is applied in a wet coating thickness of 3
Application to a thin film of ~ 15μ is performed. And
As a coating method for the upper surface of the film that runs horizontally continuously,
There are a roll coating method (transfer roll coating method), a die coating method, a spray coating method, a curtain coating method and the like.

However, it is difficult to apply the low-viscosity coating liquid in a thin film and uniformly by the above method. For example, the roll coating method is generally suitable for a coating liquid having a high viscosity of 500 cps or more, and the die coating method is suitable for a coating liquid of 3 cps.
It is applied to a coating solution of 0 cps or more and a coating thickness of 20 μm or more. If it is attempted to apply a low-viscosity liquid of 10 cps or less to a thin film of 15 μm or less by the die coating method, the liquid will run out and uniform coating is impossible. On the other hand, in the case of the spray coating method, a low-viscosity coating liquid can be applied, but the thin film coating of the spray coating method can only be applied in spots due to spraying. Moreover, when it is desired to leave the both ends of the film uncoated, a special shielding plate or the like is required. The curtain coating method is also suitable only for a highly viscous coating liquid.

A bar coating method is widely used as a method for applying a low-viscosity coating solution in a thin film and uniformly. However, the bar coating method has not been directly applied to the surface of the upper surface of the film which continuously runs horizontally. That is, FIG. 3 is an explanatory view of the conventional bar coat method,
In the conventional bar coating method, an excessive amount of coating liquid (2) is applied to the lower surface of a film (4) that continuously runs horizontally by a roller coating method or a fountain coating method, and a metalling bar (5) is used. It is weighed to a desired coating thickness, and the excess liquid is collected in the lower pan (7) and circulated. Note that FIG.
Inside, (1) is a pump, (3) is a fountain, (6) is a holder, (8) is a tank, and (9) is a roll.

When it is desired to apply the coating to the upper surface of the film which continuously runs horizontally by using the conventional bar coating method, the coating is once applied to the lower surface of the film as shown in FIG. Are folded back and run horizontally. Under such circumstances, there has been a strong demand for a coating method in which the bar coating method is applied to the upper surface of a film that continuously runs horizontally without folding and passing the film.

FIG. 4 is a schematic view in which the conventional bar coating method is applied to the upper surface of the film. In this case, as shown in FIG. The coating solution (2) is made to flow down and is applied to it (the coating solution that has flowed down is referred to as "applied solution", and its amount is referred to as "applied amount"), and then to the downstream metering bar (5). And weigh. However, in the above-mentioned coating method, when the viscosity of the coating liquid is low (10 cps or less), if the amount of the applicator from the die (11) is small, the coating liquid is faint at the die outlet and an uncoated part is generated, resulting in a uniform application. I can't. Then, the excess liquid of the other normal part spreads in the measuring part, and a liquid pool is formed and applied to the unapplied part of the applicator liquid, but the boundary between the applied part and the unapplied part at the time of application is streaked. Will be visually observed and the quality will be impaired. Furthermore, unless an application amount of about 20 times or more the desired application amount is applied by the die (11), the liquid pool formed at the contact portion between the metering bar (5) and the film (4) will be formed. It becomes non-uniform and the coating solution becomes faint in some places. In such a state, the application amount is small, and thus application streaks and application unevenness are generated due to the inclusion of bubbles, and the application appearance is impaired.

On the other hand, when a large amount is applied with the die (11), there is no blur of the liquid at the time of application, and the liquid pool in the measuring section is evenly formed and evenly applied. Excess liquid spills from both sides of the film, and equipment for collecting the excess liquid is required. Furthermore, the liquid pool formed at the contact portion between the metalling bar (5) and the film (4) spreads over the entire width, making it difficult to leave the end portion of the film uncoated. In particular, in the in-line coating method in which coating is performed during the biaxially stretched film manufacturing process, it is required that both ends of the film be uncoated, and that the uncoated width can also be adjusted arbitrarily. The reason for this is that, in the in-line coating method, generally, coating is applied after longitudinal stretching, and then the film is gripped by clips at both ends of the film in a transverse stretching machine, dried, preheated, and stretched. This is to prevent pollution. In addition, since both ends of the film after lateral stretching are thicker than the center, they do not become a product, and both ends of the film after lateral stretching are collected and recycled after slitting. So, in general,
Both ends of the film are required to be uncoated.

After the longitudinal stretching, the film enters the transverse stretching machine in a horizontal running state. Therefore, in the horizontal running state before the film enters the horizontal stretching machine, when it is desired to coat both sides, the film is coated on the upper surface. There is a request to apply. The present invention has been made in view of the above circumstances, and an object thereof is to solve the drawbacks of the coating method shown in FIG. 4 and apply a low-viscosity coating liquid to a thin film on the upper surface of a film that continuously runs in the horizontal direction. An object of the present invention is to provide a top coating bar coating method.

That is, the gist of the present invention is to apply a coating solution having a viscosity of 1 to 10 cps to a thin film having a wet coating thickness of 3 to 15 .mu. Using a coating device provided with a metalling bar supported on the bar holder part, the coating device is arranged so that the metaling bar contacts the upper surface of the film and is located on the running side of the film from the exit of the die part,
Then, the coating solution is supplied from the outlet of the die section so that a pool of the coating solution is formed immediately before the contact portion between the metalling bar and the film, and then the metering bar is used for the metering coating. It lies in the characteristic top coating bar coating method.

The present invention will be described in detail below with reference to FIGS. 1 and 2. FIG. 1 is an explanatory view showing an embodiment of the present invention, and FIG. 2 is a partial explanatory view of a coating device showing another embodiment of the present invention. The top coating bar coating method of the present invention is a coating apparatus (12) provided with a metering bar (5) supported by a holder (6 ') near the exit of a die (11').
Is used for applying a coating liquid (2) having a viscosity of 1 to 10 cps to a thin film having a wet coating thickness of 3 to 15 μm on the upper surface of a film (4) which continuously runs in the horizontal direction. The coating liquid (2) used in the present invention can be variously selected according to the purpose of coating. For example, it is an antistatic agent, an easy-adhesion lacquer, and the like, and a preferable coating liquid is a coating liquid having a viscosity of 1 to 5 cps. When the viscosity of the coating liquid (2) exceeds 10 cps, coating streaks are likely to occur in the traveling direction of the film (4) when measuring with the metering bar (5).

The coating device (12) has a die part (11 ') and a bar holder part (6'), and the metering bar (5) is supported by the bar holder part (6 '). The sides are fixed by appropriate means. The metering bar (5) is arranged so as to contact the upper surface of the film (4) and to be located on the running side of the film (4) from the exit of the die part (11 '). The coating liquid (2) in the tank (8) is supplied to the die part (11 ′) of the coating device (12) by the pump (1) and flows down like a slit onto the metering bar (5), and gravity is applied. Run off by. Then, a liquid pool (10) is formed at the contact portion between the metalling bar (5) and the film (4). The width of the liquid pool (10) is adjusted by the discharge amount of the pump (1), and the width becomes the coating width. Then, a metering bar (5) measures the coating thickness to a predetermined value.

The pump (1) is required to be quantitative and non-pulsating, and a gear pump, a uniaxial eccentric screw pump, or a non-pulsating diaphragm pump is preferably used. When a pump having no quantification and pulsation is used, the discharge amount changes, the width of the liquid pool changes accordingly, and the coating width changes. It is preferable that the gap (a in FIG. 1) of the die portion (11 ') is narrower because the spraying uniformity of the coating liquid in the width direction is improved, but if it is too narrow, it is difficult to clean the die lip portion, and thus it is usually 0. It is preferable to set the range of 0.2 to 0.4 mm.
The die lip part may be cleaned with a PET film of about 100 μm.

The support of the metalling bar (5) in the holder portion (6 ') is not limited to the support by the V-shaped groove shown in FIG. 1, but the combination of the V-shaped and the U-shaped shown in FIG. But it's okay. The coating device shown in FIG. 2 comprises two upper and lower holder parts (6 ′) and (6 ′), and the lower holder parts (6 ′) are arranged on both sides of the film (4) to be metallized. It also has the function of a fixing means for the bar (5). The material of the holder portion (6 ') is preferably stainless steel or brass from the viewpoint of rust prevention.

A wire bar or a grooving bar is used as the metering bar (5). The wire bar is a stainless steel or iron round bar in which a stainless wire or a piano wire is tightly wound in a coil shape. Usually, the round bar has a diameter of 4 to 20 mm, and the wire has a diameter of 60 to 500.
A range of μ is suitable. Then, the coating thickness is controlled by the size of the diameter of the wire. In addition, the surface of the wire bar may be plated with HCr for abrasion resistance. Usually, the metering bar (5) is normally or reversely rotated with respect to the traveling direction of the film (4), but in the present invention, it is preferably normally rotated. When rotated in the reverse direction, the coating solution (2) flowed down on the metering bar (5).
Tends to flow in the direction of rotation of the metering bar (5) against gravity, which is not preferable.

[0015]

EXAMPLES Next, the present invention will be described in more detail based on examples, but the present invention is not limited to the following examples unless it exceeds the gist thereof. The following coating solutions were used in the following examples. Polyester polyurethane (Dainippon Ink and Chemicals, Inc., trade name "Hydran AP-40") 80 parts (solid weight, the same applies below), water-dispersed polyester (Nippon Gosei Kagaku Co., Ltd., trade name "Polyester WR-" 961 ") 20 parts by weight, and a coating solution having a solid content concentration of 10% by weight and a viscosity of 2 cps using water as a medium.

Example 1 Polyethylene terephthalate having an intrinsic viscosity of 0.65 was extruded in a molten state, cast on a drum cooled to 40 ° C. by an electrostatic contact method, and subsequently, rolled by a roll-type stretching machine.
After being stretched 3.5 times in the longitudinal direction at 5 ° C., it was continuously run in the horizontal direction at a speed of 50 m / min. The running film (film width 400 mm) was coated with a coating width of 300 mm by using a coating device having the following specifications shown in FIG. Gap of die part (a in FIG. 1): 0.25 mm Land length of die part (b in FIG. 1): 50 mm Spout width of die part: 150 mm Wire bar: Round bar diameter 10 mm, wire diameter 80 μ Lateral stretching machine Was dried and preheated, stretched 3.5 times in the transverse direction at 100 ° C., heat-set at 220 ° C. and wound up. The thickness of the obtained stretched film was 12μ. In the above coating, when the target wet coating thickness was set to 4.5 μ, the target wet coating thickness could be achieved, and the coating width did not fluctuate, and stable and uniform coating was possible.

Comparative Example 1 A coating apparatus shown in FIG. 4 was used as a coating apparatus, and a die was used to apply a wire bar (round bar diameter 10 m).
m, wire diameter 80 μ), and measurement was performed in the same manner as in Example 1. The target wet coating thickness is 4.5
However, when the amount of applicator was small, the coating liquid coming out of the die was faint. Also, as a result of changing the application amount to 20 times the application amount, a liquid pool was formed at the wire bar and the film contact part without any problem, but the excess liquid spreads to both sides of the film and the entire surface was coated, resulting in a post-process. I have contaminated the clips of the horizontal stretching machine.

[0018]

According to the top-coating bar-coating method of the present invention, the viscosity of 1 on the top surface of the film continuously running in the horizontal direction.
Wet coating thickness of 3 to 10 cps low viscosity coating liquid
It can be applied uniformly to a thin film of 10 μm. Furthermore, the amount of coating liquid supplied by the pump can be adjusted according to the amount of consumption, so there is no need for equipment for collecting and circulating the coating liquid, and the film edge must be uncoated at any width. Is possible. In particular, the top coating bar coating method of the present invention is effective as an in-line coating method for an unstretched or uniaxially stretched film during the plastic stretched film manufacturing process.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing an embodiment of the present invention.

FIG. 2 is a partial explanatory view of a coating device showing another embodiment of the present invention.

FIG. 3 is an explanatory diagram of a conventional bar coating method.

FIG. 4 is a schematic view in which a conventional bar coating method is applied to the upper surface of a film.

[Explanation of symbols]

 1: Pump 2: Coating liquid 3: Fountain 4: Film 5: Metalling bar 6: Bar holder 6 ': Bar holder part 7: Pan 8: Tank 9: Roll 10: Liquid pool 11: Die 11': Die part 12 : Coating device used in the present invention

Claims (2)

[Claims] 1. When a coating liquid having a viscosity of 1 to 10 cps is applied to a thin film having a wet coating thickness of 3 to 15 μm on the upper surface of a film continuously running in the horizontal direction, the film is supported by a bar holder near the exit of the die. Using a coating device equipped with a metalling bar, the coating device is arranged so that the metalling bar is in contact with the upper surface of the film and is located on the running side of the film from the exit of the die part. An upper surface coating bar characterized in that the coating solution is supplied from the outlet of the die part so that a liquid pool of the coating solution is formed immediately before the contact with the film, and then a metering bar is used for metering coating. Coat method. 2. The film is an unstretched film or a uniaxially stretched film in a stretched film manufacturing process, and is stretched in at least one direction after coating.
Top bar coating method described.