JPH01180268A - Coating device - Google Patents

Abstract

PURPOSE:To prevent intrusion of an air layer into a coating liquid by disposing a revolving roll having the axial center approximately parallel with the rotating axial center of a back up roll on the uppermost stream side of an upper stream side lip in the web traveling direction of a coating device of a die coating system. CONSTITUTION:The coating liquid 4 transferred from the tip of the nozzle 3 to the web 2 traveling continuously in tight contact with a back up roll 1 is smoothed by the down stream side and upper stream side lips 5, 6 and is made into the prescribed coating film 8. The quantity of the air moving in an arrow direction B by sticking to the web 2 increases in the case of the high-speed coating in which the moving speed of the web 2 exceeds 200m/min. However, this air is forcibly expelled by the revolving roll 9 which is provided in nearly parallel with the rotating axial center of the back up roll 1 on the uppermost stream side of the upper stream side lip 6 in the web 2 moving direction and in proximity to the web 2 when said revolving roll moves in the direction backward of the web 2.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an improvement in a coating device that uniformly, at high speed, and efficiently coats a fixed amount of a coating liquid onto a WIJ membrane web such as film or paper. It is something.
´ Conventional technology There have been a number of conventional methods for applying coating liquids to thin webs such as various photographic films, magnetic tapes, photographic papers, etc., such as gravure coating, kiss coating, and die coating. Several coating methods have been used, and each method has been used differently depending on the purpose of use.

For example, a coating device using a die coating method, which is effective for coating magnetic tape, is constructed as shown in FIG. In this device, as shown in FIG. 4, a coating liquid 31 is continuously extruded from the tip of a nozzle 32 and transferred onto a web 33. On the other hand, the web 33 is configured to run continuously in the direction of arrow F at a constant speed in close contact with the backup roll 34. The coating liquid 31 transferred onto the web 33 is
The coating film 27 is smoothed by the lower lip 35 and the upper lip 36 of the I-bub 33 in the running direction, and a predetermined coating film 27 is formed. FIG. 5 is an enlarged view of the part shown by the arrow ■ in FIG. 4, and as shown in FIG. A coating liquid pool 39 is formed due to the pressure difference.

Problems to be Solved by the Invention However, in the coating apparatus described above, the air layer adhering to the surface of the web 33 and moving flows into the coating liquid pool 39 at approximately the same speed as the web 33. For this reason, coating liquid 3
However, there was a problem in that air bubbles were mixed into the coating film, resulting in various coating film defects listed below. In other words, pinholes are caused by the trapped air bubbles not disappearing, and the trapped air bubbles are trapped between the lower lip 35 and the I-pu 33! i
Vertical streaks that occur due to clumping, and fine particles on the surface of the coating film 37 that occur due to the flow of the coating liquid 31 being disturbed between the lower lip 35 and upper lip 36 and the web 33 due to the inclusion of air bubbles. Coating film defects such as turbulence occurred. This phenomenon was particularly noticeable in high-speed coating where the moving speed of the web 33 was approximately 2007 FL/min or more.

Therefore, the present invention prevents the air layer that adheres to the web and moves into the coating liquid pool as much as possible, and forms a high-quality coating film without pinholes or vertical streaks even during high-speed coating. A coating device is provided.

Means for Solving the Problems In order to solve the above-mentioned problems, the coating device of the present invention provides a coating device that applies a coating film from the tip of the nozzle to a web that continuously runs in close contact with the surface of a backup roll that rotates around a predetermined axis at a predetermined speed. A coating device that continuously extrudes and applies a coating liquid, and smoothes the applied coating liquid using a lower lip and an upper lip provided at the tip of the nozzle to obtain a predetermined coating film. , a rotating roll having an axis substantially parallel to the rotating axis of the backup roll is disposed on the upper side of the upper lip in the web running direction, and the outer circumferential surface of the rotating roll is brought close to the surface of the web. It is something that

The air layer adhering to the surface of the working web and moving at approximately the same speed as the web is blocked by a rotating roll provided on the upper side of the upper lip in the running direction of the upper lip and whose outer peripheral surface is close to the web. This reduces the amount of sudden air flowing into the coating liquid puddle formed at the upper lip. Roughly speaking, by rotating this rotating roll so that its outer peripheral surface moves in the opposite direction to the web, the air layer that adheres to the web and moves is forcibly removed, and the air that flows into the coating liquid pool is removed. volume is significantly reduced. As a result, even in high-speed coating where the web travel speed is much over 200 m/min, it is possible to form a high-quality coating film without pinholes or vertical streaks, just as in low-speed coating with conventional coating equipment. becomes.

EXAMPLE Hereinafter, a coating apparatus in an example of the present invention will be described with reference to the drawings.

FIG. 1 is a sectional view showing the main part configuration of a coating device in a first embodiment of the present invention. In FIG. 1, reference numeral 1 denotes a backup roll having a substantially cylindrical shape, which is rotated around a predetermined axis at a predetermined speed.

A thin film web 2 is continuously run in the direction of arrow A in close contact with the surface of the backup roll 1. Reference numeral 3 denotes a nozzle for applying the coating liquid 4 to the web 2, and a lower lip 5 is formed at the tip of the nozzle on the lower side in the running direction of the web 2.
Further, upper lips 6 are integrally formed on the upper side of the web 2 in the running direction. Of course, each lip 5
, 6 may have separate structures. Reference numeral 7 denotes a coating liquid pool formed between the upper lip 6 and the I-pipe 2 due to the pressure difference between the coating liquid pressure and the atmospheric pressure, and 8 is a coating film.

Reference numeral 9 denotes a rotating roll made of hard rubber that is disposed on the uppermost side of the web of the upper lip 6 in the normal running direction, and the rotating axis of this rotating roll 9 is approximately parallel to the rotating axis of the backup roll 1. The web 2 is disposed such that its outer peripheral surface is close to the web 2. Note that this rotary roll 9 is disposed between the backup roll 1 and the upper lip 6, and therefore has a smaller diameter than the backup roll 1.

FIG. 2 is an enlarged view of the machine direction section in FIG. In this example, the amounts (amounts) are set to approximately 51 M1 and approximately 50 μl, respectively.

The operation of the coating apparatus in the first embodiment configured as described above will be explained based on FIG. 1. A roller continuously runs from the tip of the nozzle 3 in close contact with the backup roll 1.
The coating liquid 4 transferred to the web 2 is smoothed by a lower lip 5 and an upper lip 6 provided at the tip of the nozzle 3, and a predetermined coating film 8 is formed on the surface of the web 2.

By the way, in the case of high-speed coating where the moving speed i of the pipe 2 exceeds 200 m 2 /min, the amount of air that adheres to the web 2 and moves in the direction of arrow B increases. However, the air that adheres to and moves on the I-pull 2 is provided on the uppermost side of the upper lip 6 in the moving direction of the I-pull 2, and its rotational axis is approximately parallel to the rotational axis of the backup roll 1. , and its outer circumferential surface is blocked by the rotary roll 9 which is close to the pipe 2, and the amount of air flowing into the coating liquid pool 7 is reduced. Furthermore, by rotating this rotary roll 9 in the direction of arrow C in FIG. The amount of air flowing into the coating liquid pool 7 is significantly reduced. As a result, even during high-speed coating, it is possible to form a high-quality coating film 8 without pinholes or vertical streaks. In fact, the length ρ and the gap f! shown in FIG. approximately 5 kg each
s.

When I applied videotape regular paint at a coating speed of 30,077 L/min with a depth of 50 μm,
The situation in which coating film defects occurred changed depending on whether the rotating roll 9 was provided or not. That is, by installing the rotating roll 9, the surface roughness of the coated film 8 after drying was improved and the number of vertical streaks was also reduced. When the rotary roll 9 was rotated in the direction of arrow C in FIG. The situation in which defects occur has changed significantly. That is, the surface roughness and gloss of the coating 18 after drying were greatly improved, and the number of vertical streaks and pinholes was drastically reduced.

As described above, according to this embodiment, in a die coating type coating device, a rotary roll having an axis substantially parallel to the rotation axis of the backup roll is arranged on the upper side of the upper lip in the web running direction. At the same time, by bringing the outer circumferential surface of this rotating roll close to the web and rotating this rotating roll so that the outer circumferential surface of this rotating roll moves in the opposite direction to the web surface, even during high M coating. By forcibly removing the air layer that adheres to the web and moves, it is possible to prevent it from getting mixed into the coating liquid pool as much as possible, and to form a high-quality coating film without pinholes or vertical streaks.

Next, a coating apparatus according to a second embodiment of the present invention will be described with reference to the drawings.

FIG. 3 is a sectional view showing the main part configuration of a coating device in a second embodiment of the present invention. In FIG. 3, 11 is a backup roll, 12 is an I-pu, 13 is a nozzle, and 14 is a
is the coating liquid, 15 is the lower lip, 16 is the upper lip,
17 is a coating liquid reservoir, 18 is a coating film, and 19 is a rotating roll, which is the same as the structure of the first embodiment (FIG. 1). Similarly to the first embodiment, the length ρ' of the upper lip 16 in the I-plane running direction and the gap amount Q' (minimum gap amount between the rotating roll 19 and the web 12) are approximately 5 tsm, respectively. It is set to approximately 50 μm. The difference from the configuration of the first embodiment is that a blade 20 is provided on the web side of the nozzle 13 and on the uppermost side in the web running direction, and the tip of this blade 20 is in contact with or close to the outer peripheral surface of the rotating roll 19. The point is that That is, the blade 20 can close or make the gap r121 formed between the outer peripheral surface of the rotating roll 19 and the nozzle 13 very narrow.

The operation of the coating device in the second embodiment configured as above will be explained based on FIG. 3. In the case of high-speed coating where the moving speed of the web 12 exceeds 200 m/min, the amount of air that adheres to the I-bub 12 and moves in the direction of arrow 8 increases; Rotating a rotary roll 19, which is provided on the side and whose outer circumferential surface is close to the I-pipe 12, in the direction of arrow C in FIG. 3 so that its outer circumferential surface moves in opposite directions to the I-pipe 12. As a result, the air layer adhering to and moving on the web 12 can be forcibly removed in the direction of the arrow, and as a result, the air layer adhering to and moving on the web 12 is prevented from flowing into the coating liquid pool 17 as much as possible. It can be resolved. On the other hand, an air layer is also attached to the outer peripheral surface of the rotating roll 19, and when the rotating roll 19 is rotated in the direction of arrow C, part of the air layer attached to the outer peripheral surface of the rotating roll 19 is rotated. The coating liquid pool 17 passes through the gap 21 between the outer peripheral surface of the roll 19 and the nozzle 13.
trying to flow to the side of However, due to the blade 20 provided between the nozzle 13 and the rotating roll 19,
Air attempting to flow into the gap 21 is blocked and forcibly removed as shown by arrow E, making it possible to further reduce the air layer flowing into the coating liquid pool 17. As a result, even during high-speed coating, it is possible to form a high-quality coating film 18 without pinholes or vertical streaks.

As described above, according to this embodiment, in a die coating type coating device, there is a rotary roll that forcibly removes the air layer that adheres to the web and moves, and an air layer that adheres to the outer peripheral surface of the rotary roll. By installing a blade that forcibly eliminates the air layer, even during high-speed coating, it is possible to more efficiently prevent air from getting into the coating liquid puddle, resulting in high-quality coating without pinholes or vertical streaks. A coating film can be formed.

Note that the first aspect of the present invention. In the second embodiment, the lengths ρ, ρ′ (see FIG. 2) of the upper lip 6.16 are approximately 5.
Although the size is acceptable as long as the coating liquid pool 7.17 can be stably formed, it is preferably 1 G or less in order to prevent liquid dripping due to gravity.

Also, 1st. In the second embodiment, the gap amount Q,
(: i' was set to approximately 50 μm, but
The thickness is preferably 150 μm or less in order to efficiently scrape off the gas layer that adheres to and moves.

Also, 1st. In the second embodiment, the rotating roll 9.1
Although hard rubber is used as the material of No. 9, any material may be used as long as the same effect can be obtained.

Effects of the Invention As described above, according to the configuration of the present invention, the coating liquid is continuously extruded from the nozzle tip and applied to the web that is continuously running in close contact with the surface of the backup row 1 rotating at a predetermined speed. A coating device for smoothing a coating liquid applied by a lower lip and an upper lip provided at a tip part to obtain a predetermined coating film, the upper lip having an upper side of the upper lip in the traveling direction of the pipe, By arranging a rotating roll whose axis is approximately parallel to the rotational axis of the backup roll and by bringing the outer peripheral surface of this rotating roll close to the web, it can be moved while adhering to the web even during high-speed coating. It is possible to prevent the air layer from entering the coating liquid pool as much as possible, and to form a high-quality coating film without pinholes or vertical streaks, which has great practical effects.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing the configuration of a coating device according to a first embodiment of the present invention, FIG. 2 is an enlarged view of a section viewed from arrow I in FIG. 1, and FIG. 3 is a second embodiment of the present invention. FIG. 4 is a cross-sectional view showing the structure of a conventional coating device, and FIG. 5 is an enlarged view of the section shown by the arrow ``■'' in FIG. 4. 1.11...Backup roll, 2,12...I-bu, 3.13...Nozzle, 5.15...Lower side lip, 6.16...Upper side lip, 9.19 ...Rotating roll, 20...Blade. Agent Hiroshi Morimoto Kaede Figure 2 A Figure 6 9 Figure 5

Claims (1)

[Scope of Claims] 1. A coating liquid is continuously extruded from a nozzle tip and coated on a web that continuously runs in close contact with the surface of a backup roll rotating at a predetermined speed around a predetermined axis, and The coating device smoothes the coating liquid applied by a lower lip and an upper lip provided on the upper lip to obtain a predetermined coating film, wherein the backup roll is disposed on the upper side of the upper lip in the web running direction. A coating device in which a rotating roll having an axis substantially parallel to the rotational axis is arranged, and the outer circumferential surface of the rotating roll is brought close to the surface of the web. 2. The coating device according to claim 1, wherein the rotating roll is rotated such that the outer peripheral surface of the rotating roll moves in directions opposite to the web surface. 3. The coating device according to claim 1, wherein a blade is disposed on the upper side of the nozzle tip in the web running direction, and further, the blade is arranged so that the tip comes into contact with or comes close to the outer circumferential surface of the rotating roll. 4. The length l of the upper lip in the web running direction,
The coating device according to claim 1, wherein l≦10 mm or less. 5. The minimum gap amount g between the rotating roll and the web is
The coating device according to claim 1, wherein g≦150 μm.