JP6989092B2 - Coating device - Google Patents

Description

The present invention relates to a coating device.

Conventionally, there is a coating device that applies a coating liquid to a web by a rotating bar (see Patent Document 1).

Japanese Unexamined Patent Publication No. 2009-82768

However, in a conventional coating device, air is trapped between the web and the rotating bar, which becomes minute bubbles that mix with the coating liquid and stay in the vicinity of the rotating bar, resulting in coating streaks on the web. This may occur, resulting in coating defects.

The present invention has been made in view of such circumstances, and an object of the present invention is to provide a coating device capable of reducing coating defects of a coating liquid on a web.

The present invention is grasped by the following configurations in order to achieve the above object.
(1) The coating apparatus of the present invention is a coating apparatus for applying a coating liquid to a web, and includes a bar for removing excess coating liquid applied to the web and a bar holder for rotatably supporting the bar. The bar holder has a recess below the bar, which has a passage at the bottom, one end communicating with the recess and the other end open.
(2) In the configuration of (1) above, the recess is a groove formed along the longitudinal direction of the bar.
(3) In the configuration of the above (1) or (2), the passage is formed in a slit shape along the longitudinal direction of the bar.

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide a coating device capable of reducing coating defects of a coating liquid on a web.

It is the whole view of the coating apparatus. It is sectional drawing in the front view of the coating amount adjusting apparatus which concerns on 1st Embodiment. It is sectional drawing in the front view of the coating amount adjusting apparatus which concerns on 2nd Embodiment.

(First Embodiment)
Hereinafter, a first embodiment (hereinafter, referred to as “first embodiment”) for carrying out the present invention will be described in detail with reference to the accompanying drawings. The same elements are numbered or coded the same throughout the description of the embodiments. Unless otherwise specified, the width direction of the web is the front.

FIG. 1 is an overall view of the coating device 100. FIG. 2 is a cross-sectional view of the coating amount adjusting device 20 according to the first embodiment in a front view.

The coating device 100 is a device suitable for applying a coating liquid L having a relatively low viscosity to an object to be coated such as a web 200, and is, for example, a hard coat layer, an antireflection layer, an antiglare layer, and a primer. It is applied to form a layer, a print layer, and the like.

As shown in FIG. 1, the coating device 100 includes a coating liquid supply device 10 that supplies the coating liquid L to the web 200 to apply the coating liquid L, and a coating amount adjusting device 20 that adjusts the coating amount of the coating liquid L applied to the web 200. And a guide roller 30 which is provided along the transport path of the web 200 and whose position can be adjusted.

The coating liquid supply device 10 is installed on the upstream side of the coating amount adjusting device 20 in the transport direction W of the web 200.
The coating liquid supply device 10 includes a liquid pan 11 for storing the coating liquid L and a pickup roll 12 for applying the coating liquid L stored in the liquid pan 11 to the web 200.

The liquid pan 11 is a bottomed container having a size capable of storing the coating liquid L up to a predetermined liquid level and covering the entire area in the longitudinal direction at the lowermost portion of the pickup roll 12. The liquid level of the coating liquid L stored in the liquid pan 11 is higher than the lowermost portion of the pickup roll 12 so that the lowermost portion of the pickup roll 12 is immersed in the coating liquid L.

The pickup roll 12 is a cylindrical body having an axial length equal to or larger than the width of the web 200, and is rotatably supported by a shaft support (not shown). The rotation axis of the pickup roll 12 is arranged in the width direction of the web 200, that is, in the direction orthogonal to the transport direction W of the web 200. Then, the pickup roll 12 is rotated by a drive source (not shown), or is passively rotated with the transportation of the web 200 without being driven by the drive source.

Then, the coating liquid supply device 10 transfers the coating liquid L stored in the liquid pan 11 to the lower surface of the web 200 guided by the guide roller 30 and conveyed at a predetermined speed according to the transportation of the web 200. It is continuously applied by the rotating pickup roll 12. As a result, the coating liquid L in an excess amount of the coating amount adjusted by the coating amount adjusting device 20 downstream of the coating liquid supply device 10 is applied to the web 200. As shown in FIG. 1, the rotation direction of the pickup roll 12 may be the same direction as the transport direction W (counterclockwise), but may be opposite to the transport direction W (clockwise). good.

The coating amount adjusting device 20 is installed on the downstream side of the coating liquid supply device 10 in the transport direction W of the web 200.
The coating amount adjusting device 20 includes a bar 22 and a bar holder 21 that supports the bar 22.

The bar 22 removes the excess coating liquid L applied to the web 200.
The bar 22 is a cylindrical body having an axial length equal to or larger than the width of the web 200, and is rotatably supported by a shaft support (not shown).
The bar 22 is, for example, a rod-shaped body in which a wire having a wire diameter of 1 mm is wound around a core rod having a diameter of 10 mm.
The bar 22 is in contact with the surface of the recess G of the bar holder 21. The bar 22 may be rotatably supported by a shaft support (not shown) and may be placed on the bar holder 21.
The bar 22 is rotated by a drive source (not shown) or is driven by the web 200 without being driven by the drive source. The rotation direction of the bar holder 21 may be the same as the transport direction W (counterclockwise), but may be opposite to the transport direction W (clockwise).
Then, by finely adjusting the position of the guide roller 30 with respect to the bar 22 and finely adjusting the transport path of the web 200, the uppermost end of the bar 22 is applied to the web 200 without directly contacting the web 200. It is positioned so that it bites into the layer of liquid L. Therefore, by transporting the web 200 along the transport direction W in this state, the coating liquid L excessively applied to the lower surface of the web 200 upstream is removed by being scraped off by the bar 22. The layer thickness (coating amount) of the coating liquid L can be continuously adjusted according to the transport of the web 200, and can be controlled to be uniform over the longitudinal direction of the web 200.

The bar holder 21 rotatably supports the bar 22. Like the bar 22, the bar holder 21 is a rod-shaped body extending in the width direction of the web 200, that is, in the same direction as the longitudinal direction of the bar 22. The bar holder 21 supports the bar 22 with two longitudinally extending surfaces (two points shown in FIG. 2) that are spaced apart from each other.

The bar holder 21 has a recess G below the bar 22. In other words, the recess G is a gap provided between the bar 22 and the bar holder 21. As a result, even if air is taken into the coating liquid L and bubbles are generated when the excess coating liquid L is removed, the bubbles can move to the space inside the recess G.

The recess G is a groove formed along the longitudinal direction of the bar 22. This allows the bubbles to move inside the recess G no matter where the bubbles are generated, over the longitudinal direction of the bar 22, that is, over the width of the web 200.

Further, the recess G has a passage S at the bottom, one end of which communicates with the recess G and the other end of which is open. That is, the passage S penetrates the bar holder 21. As a result, even if air is taken into the coating liquid L and bubbles are generated when the excess coating liquid L is removed, the bubbles pass through the bar holder 21 through the passage S communicating with the bottom of the recess G, so that the bar 22 Does not stay in the vicinity of. Therefore, according to the coating device 100 provided with such a bar holder 21, it is possible to more effectively suppress the generation of coating streaks due to air bubbles.
The gap of the recess G and the gap of the passage S may be the same gap having a distance d. That is, the recess G may be a part of the passage S, and one end of the passage S may be open to the support surface of the bar holder 21 supporting the bar 22.
The open other end of the passage S may communicate with a suction device (not shown). In this case, since the pressure in the passage S can be controlled to be lower than the atmospheric pressure by the suction device, the bubbles staying in the recess G can be positively sucked through the passage S. Therefore, it is possible to more effectively suppress the generation of coating streaks due to air bubbles.

Further, the passage S is formed in a slit shape along the longitudinal direction of the bar 22. This makes it possible to effectively suppress the generation of coating streaks due to air bubbles over the width direction of the web 200.
The passage S is not limited to an L-shaped cross section as shown in FIG. 2, and may have an I-shaped cross section of the alphabet, that is, a straight passage in the vertical direction.

By the way, as shown in FIG. 2, the bar holder 21 includes a first holder portion 21A and a second holder portion 21B. The first holder portion 21A and the second holder portion 21B are separate members, and each has a uniform cross section in the longitudinal direction, that is, as shown in FIG. 2. The first holder portion 21A has an L-shaped cross section of the alphabet, the second holder portion 21B has an I-shaped cross section of the alphabet, and the second holder portion 21B is arranged so as to fit into the recess of the first holder portion 21A. Will be done.
Then, in a state where a gap is formed between the first holder portion 21A and the second holder portion 21B with a distance d in the transport direction W (left-right direction in FIG. 2) of the web 200, the first holder portion 21A and the second holder portion 21B are connected to each other by a bolt or the like (not shown). It is combined. And this gap becomes a passage S. In this way, the bar holder 21 provided with the passage S having a gap of the distance d can be easily manufactured.

(Second Embodiment)
Next, a second embodiment (hereinafter, referred to as “second embodiment”) for carrying out the present invention will be described in detail with reference to the accompanying drawings. The same elements are numbered or coded the same throughout the description of the embodiments. Since the structure of the bar holder 21 is different in the second embodiment as compared with the first embodiment, the bar holder 21 will be mainly described below, and common parts may be omitted.

FIG. 3 is a cross-sectional view of the coating amount adjusting device 40 according to the second embodiment in a front view.
The coating amount adjusting device 20 according to the second embodiment includes a bar 42 and a bar holder 41 for supporting the bar 42, similarly to the coating amount adjusting device 20 according to the first embodiment.

The bar holder 41 has a recess G1 below the bar 42. In other words, the recess G1 is a gap provided between the bar 42 and the bar holder 41. As a result, even if air is taken into the coating liquid L and bubbles are generated when the excess coating liquid L is removed, the bubbles do not stay in the vicinity of the bar 42 and move to the space inside the recess G. It will be possible.

The recess G1 is a groove formed along the longitudinal direction of the bar 42. As a result, the bubbles can move inside the recess G regardless of where the bubbles are generated, over the longitudinal direction of the bar 42, that is, over the width direction of the web 200.

Further, the recess G1 has a passage S1 at the bottom, one end of which communicates with the recess G1 and the other end of which is open. That is, the passage S1 penetrates the bar holder 41. As a result, even if air is taken into the coating liquid L and bubbles are generated when the excess coating liquid L is removed, the bubbles do not stay in the vicinity of the bar 42 and travel through the passage S1 communicating with the bottom of the recess G1. And pass through the bar holder 41. Therefore, according to the coating device 100 provided with such a bar holder 41, it is possible to more effectively suppress the generation of coating streaks due to air bubbles.

Here, the bar holder 41 according to the second embodiment has a recess G2 and a recess G3 in addition to the recess G1. That is, the bar holder 41 has one or more recesses (G2) on the upstream side (right side in FIG. 3) or the downstream side (left side in FIG. 3) of the bar 42, in addition to the recess G1 held below the bar 42. , G3, ...). This makes it possible to more effectively suppress the generation of coating streaks due to air bubbles.

Further, the recess G1, the recess G2 and the recess G3 have a passage S1, a passage S2 and a passage S3 at the bottom thereof, one end communicating with the recess G1, the recess G2 and the recess G3, and the other end open. That is, the passage S1, the passage S2, and the passage S3 penetrate the bar holder 41. As shown in FIG. 3, the passage S1, the passage S2, and the passage S3 may be merged in the middle and the other ends of the passages S1 may be opened at a common place. As a result, even if air is taken into the coating liquid L and bubbles are generated when the excess coating liquid L is removed, the bubbles are formed from the space inside the recesses G1, the recesses G2, and the recesses G3, from the space inside the recesses G1, the recesses G2, and the recesses G3. Since it passes through the bar holder 41 through the passage S1, the passage S2, and the passage S3 communicating with the bottom of the recess G3, it does not stay in the vicinity of the bar 42. Therefore, according to the coating device 100 provided with such a bar holder 41, it is possible to more effectively suppress the generation of coating streaks due to air bubbles.

Further, the passage S1, the passage S2, and the passage S3 are formed in a slit shape along the longitudinal direction of the bar 42. This makes it possible to effectively suppress the generation of coating streaks due to air bubbles over the width direction of the web 200.
The passage S1, the passage S2, and the passage S3 have a cross section as shown in FIG. 3 if one end communicates with the recess G1, the recess G2, and the other end is open from the bar holder 41. Not limited to.

By the way, as shown in FIG. 3, the bar holder 41 includes a first holder portion 41A and a second holder portion 41B. The first holder portion 41A and the second holder portion 41B are separate members, and each has a uniform cross section in the longitudinal direction, that is, as shown in FIG. The first holder portion 41A has an L-shaped cross section of the alphabet, and the second holder portion 41B has an I-shaped cross section of the alphabet, and has a recess G1, a recess G3, a passage S1 and a passage S3. The second holder portion 41B is arranged so as to fit into the recess of the first holder portion 41A.
A bolt or the like (not shown) is provided between the first holder portion 41A and the second holder portion 41B in a state where a gap is formed between the first holder portion 41A and the second holder portion 41B with distances d2 and d3 in the transport direction W (left-right direction in FIG. 2) of the web 200. Combined with each other. And this gap becomes passages S2 and S3.
In this way, the bar holder 41 provided with the passage S2 having the gap of the distance d2 and the passage S3 having the gap of the distance d3 can be easily manufactured.

The distance d1, the distance d2, and the distance d3 of the respective gaps of the passage S1, the passage S2, and the passage S3 may be the same, but the distance d2 and the distance d3 may be smaller than the distance d1. As a result, the generated bubbles can be effectively guided to the other end.

(Example 1)
The test was performed using the coating device 100 provided with the bar holder 21 shown in FIG.
Specifically, a bar 22 in which a wire having a wire diameter of 1 mm is wound around a core rod having a diameter of 10 mm is supported by a bar holder 21 having a passage S having a gap distance d of 1 mm, and a urethane film having a thickness of 100 μm is used as a web 200. The coating liquid L was applied while transporting the film at a line speed of 15 mm / min.
The coating liquid L was a coating agent containing toluene as a solvent, containing a fluororesin, having a viscosity of 10 mPa · s, and a surface tension of 25 mN / m. The viscosity was calculated from the shear viscosity obtained by the steady flow measurement of 0.1 (1 / s) using the rotation mode of the viscoelasticity measuring device (“MCR302” manufactured by Anton Pearl Japan Co., Ltd.). The surface tension was measured by a vertical plate method (Wilhelmy method) using a platinum plate (manufactured by Kyowa Interface Science Co., Ltd.) as a plate-shaped member. The contact angle of the coating liquid L with the platinum plate was 0 °.
The specific measurement method of the vertical plate method (Wilhelmy method) is as follows. A sample liquid (coating liquid) is placed in a container, the tip of the plate-shaped member is vertically immersed in the sample liquid, and tension P is applied upward to the plate-shaped member. The weight of the plate-shaped member is M, the immersion depth of the plate-shaped member is h, the area of the horizontal cross section of the plate-shaped member is s, the length around the horizontal cross section of the plate-shaped member is L, the density of the liquid is ρ, and the surface. Assuming that the tension is γ, the upward force (tension + buoyancy) and the downward force (gravity + surface tension) are balanced as shown in the following equation (1).
P + shρg = Mg + Lγ ・ ・ ・ (1)
The surface tension γ (mN / m) of the sample liquid can be obtained from the equation (2) which is a modification of the equation (1).
γ = (P + shρg-Mg) / L ... (2)
The rotation speed of the bar 22 was 90 rpm (reversal).
The thickness of the coating film was about 50 μm (before drying), and the coating length was 1000 m.
As a result, when the obtained coating film was visually observed, no coating streaks due to air bubbles were observed.

(Example 2)
The coating liquid L was applied in the same manner as in Example 1 except that the line speed was set to 20 m / min.
As a result, when the obtained coating film was visually observed, no coating streaks due to air bubbles were observed.

(Example 3)
The coating liquid L was applied in the same manner as in Example 1 except that toluene was used as a solvent and a coating agent containing an acrylic resin and having a viscosity of 30 mPa · s and a surface tension of 25 mN / m was used as the coating liquid.
As a result, when the obtained coating film was visually observed, no coating streaks due to air bubbles were observed.

(Example 4)
The coating liquid L was applied in the same manner as in Example 1 except that the distance d of the gap in the passage S of the bar holder 21 of Example 1 was changed to 0.5 mm.
As a result, when the obtained coating film was visually observed, no coating streaks due to air bubbles were observed.

(Comparative Example 1)
The coating liquid L was applied in the same manner as in Example 1 except that the bar holder 21 having no passage S was used.
As a result, coating streaks caused by air bubbles were generated immediately after the start of coating.

(Comparative Example 2)
The coating liquid L was applied in the same manner as in Example 3 except that the bar holder 21 having no passage S was used.
As a result, coating streaks caused by air bubbles were generated immediately after the start of coating.

As described above, according to the results of Examples 1 to 4 and Comparative Examples 1 and 2, when the distance d of the gap in the passage S is 1 mm or 0.5 mm, the effect of suppressing the generation of coated streaks due to air bubbles can be obtained. Obviously obtained.

Although the present invention has been described above based on specific embodiments, the present invention is not limited to the above embodiments.

According to the coating device 100 of the present invention, in the coating device 100 for applying the coating liquid L to the web 200, a bar 22 for removing the excess coating liquid L applied to the web 200 and a bar holder for rotatably supporting the bar 22. Since the bar holder 21 has a recess G below the bar 22, it is possible to suppress the generation of coating streaks due to air bubbles and reduce coating defects of the coating liquid L on the web 200.

10 Coating liquid supply device 11 Liquid pan 12 Pickup roll 20, 40 Coating amount adjusting device 21, 41 Bar holder 21A, 41A First holder section 21B, 41B Second holder section 22, 42 Bar 30 Guide roller 100 Coating device 200 Web d Distance d1 distance d2 distance d3 distance G dent (groove)
L Coating liquid S Passage S1 Passage S2 Passage S3 Passage W Transport direction

Claims (2)

In a coating device that applies a coating liquid to the web
A bar that removes excess coating liquid applied to the web,
With a bar holder that rotatably supports the bar,
The bar holder has a recess below the bar.
The recess has a passage at the bottom, one end communicating with the recess and the other end open.
The entire area from one end to the other end of the passage is formed in a slit shape along the longitudinal direction of the bar .
The bar holder is formed by combining a first holder portion and a second holder portion formed separately from the first holder portion.
The first holder portion and the second holder portion are combined with each other in a state where a gap serving as a passage is formed between the first holder portion and the second holder portion. Coating device. The coating device according to claim 1, wherein the recess is a groove formed along the longitudinal direction of the bar.

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