JPH02139063A - Coating device - Google Patents

Abstract

PURPOSE:To make quality uniform by providing a hollow roll which rotates in close contact with a web and a vacuum roll which sucks the interior of the hollow roll. CONSTITUTION:A hollow roll 20 is provided right before an application device 5 so that the droll comes in contact with a web 3. The boundary layer of an accompanied air flow 10 which grows into a thick flow from the upstream side of the web 3 is shut off and at the same time, the boundary layer which develops on the surface of the web 3 at the downstream side of the hollow roll 20 is blocked by suction by a vacuum pump 2 so that its further development does not occur. Consequently, the accompanied air flow 10 which collides with the surface 4a of a coating liquid 4 is reduced and therefore, irregularities in the application of the coating liquid 4 to the surface of the web 3 can be eliminated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a coating device that is applied to, for example, top-coating a coating liquid onto paper.

[Conventional technology]

FIG. 3 is a sectional view of a conventional blade coater type coating device. In the figure, a packing roll 2 has an elastic body 1 such as rubber wrapped around its outer circumferential surface, and a web 3 is wound around the outer circumference of the packing roll 2 for transport.

At the bottom of the packing roll 2, a coating liquid 4 is sprayed upward from a nozzle 5a toward the bottom surface of the web 3.
A coating device 5 is provided for adhering to. Further, a blade 7 is provided downstream in the transport direction of the web 3 for removing excess coating liquid 4 to form a constant coating liquid layer 6'f on the surface of the web 3. 8 is a blade holder.

[Problem to be solved by the invention]

In the conventional coating device as described above, when the surface 4a of the coating liquid 4 ejected from the nozzle 5a of the coating device 5 is disturbed, the surface of the adhesion surface 4b on which the coating liquid 4 adheres to the web 3 also becomes uneven. Even if the coating liquid 4 is measured and removed by the blade 7, the amount of the coating liquid 4 that adheres to the web 3 will not be uniform in the width direction, and the thickness of the coating layer 6 will also be affected by this, resulting in a decrease in the quality of the product. I am having a problem with this.

The reason why the surface of the adhesion surface 4b is disturbed is due to the entrained air flow 10 that is entrained by the running web 3 due to the frictional force 9.
The sprayed coating liquid 40 collides with the surface 4allC, disturbs the surface 4a unevenly in the width direction, and a part
It is conceivable that the uniformity of the coating liquid 4 in the width direction may be disturbed due to non-uniform penetration of the coating liquid 4 into the coating liquid 4 in the width direction.

[Means to solve the problem]

The coating device according to the present invention aims to solve the above-mentioned problems, and includes a coating device that sprays a coating liquid onto a web that is wound around a packing roll and is transported, and a coating device that sprays a coating liquid on a peripheral surface upstream in the direction of web transport. The present invention is characterized by a structure 1 comprising a hollow roll having a large number of holes and rotating in close contact with the web, and a vacuum pump sucking air inside the hollow roll.

[Effect]

That is, in the coating apparatus according to the present invention, a hollow roll having a large number of holes on the circumferential surface is provided in close contact with the web before the apparatus for applying the coating liquid to the web. At the same time, the boundary layer of the entrained air flow that grows thick and flows from the hollow roll is blocked, and at the same time, the boundary layer of the entrained air flow that develops on the web surface on the downstream side of the hollow roll is suctioned by a vacuum pump. do.

〔Example〕

1 and 2 are cross-sectional views of a coating apparatus according to an embodiment of the present invention. As shown in FIG. 1, the coating device according to the present embodiment has a hollow roller that rotates with the web 3 sandwiched between one packing roll 2 and one packing roll 2 upstream of the coating device 5 in the web 3 transport direction. A roll 20 is provided. Figure 1 shows the cross section of the hollow roll 20, and Figure 2 shows the cross section of the hollow roll 20.
The cross section and appearance of the figure are shown. The hollow roll 20 has a second
As shown in the figure, a large number of small holes 22 are provided in the face 21 to communicate an internal space 24 with the outside, and this internal space 24 is connected to a vacuum pump 29 by a hollow shaft 27 through a girotary joint 26. is connected to.

A cover 23 is provided on the outside of the hollow roll 20 (close to the hollow roll 20), and this prevents air other than the vicinity of the web 3 from being sucked in. This hollow roll 20 is driven by a motor. Momo! Patsu King Roll 2
It may also be in a state where it moves along with the body. 25 is a bearing, and 28 is a shaft.

In this way, by providing the hollow roll 20 in close contact with the web 3 immediately before the coating device 5, the boundary layer of the entrained air flow 10 that thickens and flows from the upstream side of the web 3 is blocked, and at the same time, the hollow roll 20 is installed in close contact with the web 3. The boundary layer that develops on the surface of the web 3 on the downstream side of the roll 20 is sucked by the vacuum pump 29 to prevent its development. Generally 1 this entrained air flow 10
The boundary layer thickness δ is expressed by the following equation.

ν 1 δ=0.37(v;2−)x where ■ is the speed of the web 3, ν is the kinematic viscosity of the air, and X is the distance from the starting point of boundary layer development. As the distance X increases, the boundary layer thickness δ increases approximately in proportion to it. Therefore, if the hollow roll 20 is provided immediately before the coating device 5, then K
By making the distance X very short, the entrained air flow IQ of web 3
=i can be blocked.

Therefore, in this coating equipment construction, the entrained air flow 10 colliding with the surface 4a of the cord liquid 4 is reduced, and disturbance of the adhesion surface 4b of the coating liquid 4 to the web 3 is prevented. The thickness becomes uniform in the width direction. Further, paper powder, dust, etc. that are carried from the upstream side of the web 3 by the entrained air flow 10&C and adhere to the surface of the web 3 are also absorbed into the hollow roll 20 and removed together with the entrained air flow 10.

〔Effect of the invention〕

The coating device according to the present FIA8C has the above-mentioned through-hole configuration, and the entrained airflow of the web is blocked and sucked, so the entrained airflow that collides with the surface of the coating liquid is reduced, and the entrained airflow that impinges on the surface of the coating liquid is reduced. Disturbance of the adhesion surface is prevented and the thickness of the coating layer becomes uniform in the width direction, and paper powder and dust that is carried by the entrained air flow from the upstream side of one web and adheres to the surface of the web is also entrained. Since it is absorbed and removed along with the air flow, it has the effect of improving product quality.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of a coating device according to an embodiment of the present invention, Fig. 2 is a cutaway view taken along the -n arrow in Fig. 1, and Fig. 3 is a sectional view of a conventional coating device. be. 2... Packing roll, 3... Web, 4...
Coating liquid, 5... Application device, 10... Entrained air flow,
20... Hollow roll, 21... Curved surface, 22... Small hole, 23... Cover 24... Space, 26... Rotary joint, 27... Hollow shaft, 29
...Vacuum pump 1st and 3rd figure agent Patent attorney Akatsuki Sakama 2nd person 2nd figure

Claims (1)

[Claims] Upstream in the web transport direction of a coating device that spouts a coating liquid onto the web being wound around a packing roll and transported, there is a hollow roll provided with a number of holes on its circumferential surface and rotates in close contact with the web; A coating device characterized by comprising a vacuum pump that sucks air inside the roll.