JPH0275375A - Coating apparatus - Google Patents

Abstract

PURPOSE:To uniformly form a coating layer on a web in the laterial direction of the web by providing a means for blocking an air layer on the upstream side in the web transfer direction of an apparatus for coating the web with a coating solution to block the air layer accompany the web. CONSTITUTION:A blocking roll 11 is provided immediately before a spray device 5 for ejecting a coating solution to a web 3 to coat said web 3 to be closely brought into contact with the web and blocks the air layer 10 accompany the web 3. As a result, the coating solution 4 ejected to the web 3 to be applied thereto is not disturbed by the air layer 10 and a coating layer 6 having a uniform thickness is formed on the web 3.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a coating device used, for example, when coating a web with a coating liquid.

[Conventional technology]

Fig. 5 is an explanatory diagram of the mechanism of a conventional coating device also called a blade coater. Transfer the web 3 by wrapping it 5 times.Backing roller 2
A blowing device 5 is provided that sprays coating liquid 4 upward from a nozzle 5a toward the lower surface of the lower web 3, and a blade 7 is provided downstream of the blowing device 5 in the transport direction of the web 3. is installed to remove excess coating liquid 4 and form a constant coating layer 6 on the web 3.

8 in the figure is a blade holder.

[Problem to be solved by the invention]

In the conventional coating device as described above, the coating liquid t4 is sprayed from the nozzle 5& of the blowing device 5 onto the surface 4a.
The adhesion surface 4b to the web r) 3 becomes irregular when the web r) is disturbed.
The coating layer 6 of the web 3 may not be uniformly formed in the width direction of the web 3 even if it is measured by the blade 7, resulting in a problem that may lead to quality deterioration. I know this from experience. The cause of the turbulence of the coating liquid 4 is the air layer 10 that is entrained by the web 3 being transferred due to friction, which causes the surface 4a of the coating liquid 40 to become turbulent.
Not only does the collision disturb the web 3 non-uniformly in the width direction, but also a part of the air layer 10 may enter the surface 4b to which the coating liquid 4 is attached non-uniformly in the width direction of the web 3 and disturb it. Conceivable.

[Means to solve the problem]

The coating apparatus according to the present invention aims to solve the above-mentioned problems, and has a means for blocking an air layer entrained in the web upstream in the web transport direction of the apparatus that applies a coating liquid to the web. It is characterized by a configuration that includes.

[Effect]

That is, in the coating apparatus according to the present invention, a means for blocking the air layer is provided upstream in the web transport direction of the apparatus for applying the coating liquid to the web, so that the air layer entrained in the web is blocked. It is now possible to do so.

Generally, the thickness δ of the air layer entrained in the web is expressed as follows. However, ν is the kinematic viscosity of the air, V is the transport speed of the web, and X is the distance from the starting point of the air layer. As this distance X increases, the thickness δ increases in proportion. Therefore, by providing a means for blocking the air layer upstream of the device that applies the coating liquid, the distance X becomes much shorter than K, so it is possible to effectively block the air layer entrained in the web. .

〔Example〕

Embodiments of the present invention will be described based on FIGS. 1 to 4.

1 to 3 are mechanism explanatory diagrams of coating apparatuses according to first to third embodiments of the present invention, and FIG. 4 is an operational explanatory diagram of the coating apparatus according to the third embodiment. . In addition, No. 5 in the figure
Components common to those in the drawings are given the same reference numerals as those in FIG. 5, and explanations thereof will be omitted.

In FIG. 1, the coating apparatus according to the first embodiment includes a blocking roll 11 and a packing roll 2 provided on the upstream side of the blowing device 5 in the direction of conveying the web 3, as shown in the figure. This cutoff roll 11 is wider than the width of the web 3 and is driven separately by a motor (not shown), or
Alternatively, it is configured to rotate as the packing roll 2 rotates. The air layer 10 entrained in the web 3 is blocked by this blocking roll 11. In this way, in this coating device, the blocking roll 11 is provided just before the blowing device 5 that sprays and coats the coating liquid 4 onto the web 3.
Since the air layer 10 entrained in the web 3 is blocked by keeping it in close contact with the web 3, the coating liquid 4 sprayed onto the web 3 is not disturbed by the air layer 10, and the web 31C has a uniform thickness. Coat layer 6 is formed.

In FIG. 2, the coating device according to the second embodiment is provided with a nozzle 21 for supplying air upstream of the blowing device 5 in the direction of conveying the web 3, as shown in the figure. As shown in FIG. 2(b), the web 3 is blown out to face the air layer 10 entrained by the web 3.
It has a lip 24 that opens in a direction 22 opposite to the direction of transport. The nozzle 21 secures air ejected across the width of the web 3, and is filled with particles 23, for example. Air is ejected from the lip 24 of this nozzle 21 toward the air layer 10, and the air layer 10 entrained by the web 3 is blocked. In this way, in this coating device, immediately before the blowing device 5 which injects and coats the coating liquid 4 onto the web 3, a slit-shaped device is installed which blows out air in the upstream side in the direction 22 opposite to the transport direction of the web 3. A nozzle 21 is provided which has a lip 24 that opens to the web 3.The nozzle 21 is provided with a lip 24 that opens to the web 3, and by jetting out air at a flow rate equal to or higher than the transport speed of the web 3, the air layer 10 entrained by the friction of the web 3 is pushed back and the web The turbulence caused by the air layer 10 in the coating liquid 4 sprayed onto the coating liquid 3 is reduced.

In FIG. 3, the coating device according to the third embodiment has a flat solid wall 31 provided on the upstream side of the blowing device 5 in the direction of conveyance of the web 3, as shown in FIG. 3(a)K. There is. This solid wall 31 has a width equal to or greater than the width of the web 3, and is appropriately fixed to a frame or the like. The cross-sectional shape of this solid wall 31 is
As shown in Figure (b), when the web 3 is transferred to the right in the figure, the tip of the solid wall 31 has a sharp edge shape toward the upstream side in the transport direction of the web 3. It has a shape that can block the air layer 10 and suppress turbulence of the coating liquid 4 on the downstream side as much as possible. In addition, as shown in FIG. 3(c) K, the solid wall 31 has a structure in which an elastic body 32 such as rubber is attached to the tip so that even if the web 3 comes into contact with the solid wall 31, troubles such as paper breakage do not easily occur. You can also do it. In this way, in this coating device, a flat solid wall 31 is provided immediately before the blowing device 5 and slightly separated from the web 3, and the solid wall 31 and the web 3 are connected to each other.
The flow rate of the air layer 10 passing between the two can be effectively and easily blocked.

It has been found through experiments that if a flat solid wall 31 is provided immediately before the blowing device 5 with its tip slightly separated from the web 3, the air layer 10 entrained in the web 3 can be effectively blocked. That is, as shown in FIG. 4(a), a solid wall 31 is attached upstream in the direction of rotation of the backing roller 2 of the blade 7 that is in contact with the rotating backing roller 2, and the gap δ between the tip of the solid wall 31 and the backing roller 2 is FIG. 4(b) shows the flow velocity distribution in the circumferential direction of the air layer measured along the radial direction of the backing roller 2 on the downstream side in the rotational direction of the backing roller 2 while changing the rotation direction. As can be seen from the figure, the flow velocity on the surface of the backing roller 2 cannot be reduced except by reducing the gap δ to zero, but the flow velocity V at a position slightly distant from the surface of the backing roller 2 can be significantly reduced by providing the solid wall 31. has been effectively reduced. Note that if the solid wall 31 is brought into contact with the surface of the backing roller 2, the air layer can of course be completely blocked.

〔Effect of the invention〕

The coating apparatus according to the present invention is configured as described above, and since the air layer accompanying the web is blocked, the coating liquid applied to the web is not disturbed.

Therefore, effects such as a coating layer with a uniform thickness being formed on the web can be achieved.

[Brief explanation of the drawing]

1 to 3 are mechanism explanatory diagrams of the coating apparatus according to the first to third embodiments of the present invention, and FIG. 4 is an explanatory diagram of the operation of the coating apparatus according to the third embodiment. FIG. 5 is a mechanical explanatory diagram of a conventional coating device. 3... Web, 4... Coating liquid, 5... Blowing device, 6... Coating layer, 7... Blade,
10... Air layer, 11... Shutoff roll, 21...
・Nozzle, 24... Lip, 31... Solid wall, 3
2...Elastic body. Agent Patent Attorney Akatsuki Sakama 42 figures (b) 3 countries (α) (b) 4 agony ↑ roller and 1 straw 5 figures,

Claims (1)

[Claims] A coating device comprising means for blocking an air layer entrained in the web upstream in the web transport direction of the device for applying a coating liquid to the web.