JPH04284878A - Web coating apparatus - Google Patents

Abstract

PURPOSE:To obtain good coating properties under a flotation feed system and to especially prevent the generation of lateral irregularity in level and oblique irregularity. CONSTITUTION:In an apparatus wherein a web 3 is fed in a floated state while air is injected to the surface opposite to the surface to be coated of the web and the coating solution allowed to flow out of a coating apparatus is applied to the surface to be coated of the web while a bead is formed, a vacuum chamber 7 is provided in the direction opposite to the feed direction of the web 3 so as to surround a head forming region from an uncoated web region, and the apparatus is reduced in pressure through the vacuum chamber 7. The web 3 is passed through the vacuum chamber 7 and clearance is substantially eliminated between the open surfaces of both side walls 7a in the feed direction of the web 3 and the opposed surface of an air injector 1.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for applying a coating liquid to the opposite surface of a web being floated and conveyed.

0002

2. Description of the Related Art A so-called slide bead coating device is used for multilayer coating in the production of photosensitive materials.

Japanese Patent Publication No. 12107/1983 discloses such an apparatus and the physical properties of the coating liquid used therein.

On the other hand, Japanese Patent Publication No. 49-17853 discloses that a hollow drum is formed with a large number of gas jetting ports, and during the process of conveying the web around the hollow drum, gas is jetted out from the gas jetting ports to blow the web. It is known that coating is carried out while floating from the drum.

Furthermore, US Pat. No. 2,681,294
No. 2, No. 2003-116029 discloses that a vacuum chamber is provided below the bead formation site to stabilize the bead.

[0006]

[Problem to be solved by the invention] Said Japanese Patent Publication Publication No. 49-17
The web floating conveyance method described in Publication No. 853 is as follows:
Compared to the method of transporting through a group of transport rollers,
Even if there is already a coating layer on the side opposite to the coating surface, there are advantages such as the ability to coat without damaging the coating layer on the opposite side. This publication also provides a detailed explanation of the advantages and disadvantages of the conventional method.

On the other hand, as mentioned above, US Patent No. 2,68
In No. 1,294, in the slide bead application method, a vacuum chamber is provided below the bead formation point to stabilize the bead, and although it certainly contributes greatly to stabilizing the bead, this technology is only limited to The web is conveyed while being held in the form of a back roll, and the depressurizing effect of the decompression chamber has no effect on the conveyance of the web.

However, the present inventors have improved the applicability and
Furthermore, when coating a web that has a coating layer on the opposite side, the above-mentioned floating conveyance method is effective, and by stabilizing the floating conveyance of the bead and web using a vacuum chamber, extremely good coating properties can be obtained. I discovered that.

Furthermore, under such a configuration, a new problem was encountered. That is, as shown in FIGS. 5 and 6, if the upper end surface of the side wall 7A of the decompression chamber 7 and the outer surface of the blowing drum 1 of the gas injector are separated by a gap L,
If the gap L is too narrow, the uncoated parts at both ends of the web 3 will come into contact with the upper end surface of the side wall 7A, the web 3 will vibrate during the conveyance process, and horizontal unevenness will occur in the coating layer, and conversely, the gap L will be too small. If it is too wide, outside air will flow into the vacuum chamber 7 as indicated by the arrow in FIG. 6, and the flow of this outside air will disturb the bead and cause diagonal unevenness in the coating layer of the web 3.

[0010] Therefore, an object of the present invention is to obtain good coating properties under the floating conveyance system, and particularly to prevent the occurrence of horizontal unevenness and diagonal unevenness.

[0011]

[Means for Solving the Problems] The above object is to apply a coating liquid discharged from a coating device to the coating surface while floating and conveying the web while injecting gas to the surface opposite to the coating surface. In an apparatus for coating a web while forming beads, a vacuum chamber is provided surrounding the bead formation region from the uncoated web region and in a direction opposite to the web conveyance direction, and the pressure is reduced through the vacuum chamber. This problem can be solved by making the web pass through the reduced pressure chamber, and by creating substantially no clearance between the open end surfaces of both side walls in the web conveyance direction and the opposing surface of the gas ejector.

0012

[Operation] In the present invention, during the process of floating and transporting the web using a gas injector, etc., bead (coating liquid in a cross-linked state when the coating liquid from the coating device is transferred to the web surface) formation area is removed from the uncoated web area. A vacuum chamber is provided surrounding the web and in a direction opposite to the transport direction of the web, and the pressure is reduced through this vacuum chamber.

[0013] According to the present invention, the web is passed through the vacuum chamber, and when there is substantially no clearance between the open end surfaces of both side walls in the web transport direction and the opposing surface of the gas jet, the web passes through the vacuum chamber. Since contact with the side wall of the web can be prevented, vibration of the web can be eliminated, thereby preventing the occurrence of horizontal step unevenness. In addition, since the inflow of outside air is prevented, the bead is not disturbed and the occurrence of diagonal unevenness at the side edges can be prevented.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below with reference to the drawings.

In FIG. 1, reference numeral 1 denotes a hollow air blowing drum, and its approximately semi-cylindrical wall has blowing holes 1a, 1a, . . .
are formed in large numbers. A blower 2 is connected to the drum 1, and air from the blower 2 is discharged from each outlet 1a, 1a, . . . .

[0016] The web 3 enters the gas ejector via a group of four conveying rollers, and in the embodiment rotates clockwise around the drum 1 by about 180 degrees to reach a downstream cold air zone (not shown) or the like. It is manufactured into a product through a gelling process that includes cooling means.

Bead coating is applied to the web 3 from the coating device 5 while the web 3 is floated and conveyed around the drum 1 by the air pressure discharged from the gas injector. In the embodiment, this coating device 5 has two outflow slits 5A.
, 5B, and two layers of different coating liquids 6A and 6B are applied onto the web 3. That is, the coating liquids 6A and 6B pushed into the liquid reservoirs 5C and 5D formed in the coating device 5 via pumps flow out from the outflow slits 5A and 5B, and flow onto the web 3 in a two-layered state. At this time, there is a slight clearance between the shoulder of the head of the coating device 5 and the surface of the web 3, and the web 3 is being conveyed continuously, so each coating liquid 6A, 6B is applied between the shoulder of the coating head and the surface of the web 3. It is continuously applied in a crosslinked state while forming beads with the surface of the web 3.

On the other hand, in the present invention, the coating device 5
A vacuum chamber 7 is provided surrounding the bead forming area from the uncoated web area and in the opposite direction (downward) to the web conveyance direction.

In the embodiment, the entrance side edge 7a of the web 3 of the reduced pressure chamber 7 is close to the lower surface of the web 3, and its left end in FIG. 1 is in contact with the coating device 5 without any clearance. Further, the reduced pressure chamber 7 is connected to a reduced pressure means such as a blower via a conduit 8.

[0020] In the coating device configured as described above, when the web 3 which has already been coated on the opposite side or the web which does not have a coating layer on the opposite side circulates around the air blowing drum 1, each of its blowing ports 1a , 1a..., and the web 3 is conveyed in a floating state. During this conveyance process, the coating liquids 6A, 6 are transferred from the coating device 5.
Two layers of B are applied.

Furthermore, at the same time, the vacuum chamber 7 is evacuated via the conduit 8, and as a result, a downward pulling force acts on the bead formed between the shoulder of the coating head and the surface of the web 3. , thereby stabilizing the crosslinked state.

Now, in the present invention, as particularly shown in FIGS. 1 and 2, there is substantially no clearance between the outer surface of the blowing drum 1 and the upper end surface of the side wall 7A of the decompression chamber 7. That is, they are contacted without any clearance within a range that can prevent the inflow of outside air. Further, the web 3 is configured to be passed through a reduced pressure chamber 7.

As a result, the web 3 does not come into contact with the upper end surface of the side wall 7A of the decompression chamber 7 and is conveyed in a vibrating state, thereby eliminating lateral row unevenness. Moreover, as is clear from FIG. 2, there is no inflow of outside air, thereby preventing the occurrence of diagonal unevenness.

In the present invention, the outer surface of the blowing drum 1 and the upper end surface of the side wall 7A of the decompression chamber 7 may be completely integrated. Furthermore, as shown in FIG.
or by the sealing tongue piece 11 as shown in FIG.
Clearance can also be nullified.

On the other hand, in FIG. 1, a tangent line L1 at the entry position of the web 3 into the vacuum chamber 7, in the example, the entry side edge 7a, and a tangent line L2 to the web at the bead forming position.
It is preferable that the intersection angle θ is 145 degrees or less. On the other hand, if it exceeds 145 degrees, that is, if the distance from the entrance edge 7a to the bead formation position is short, it becomes difficult to balance the floating amount in the width direction, and it is also difficult to sufficiently eliminate the vibration of the web 3. The lower limit of the intersection angle θ is not limited, but is preferably 45 degrees or more.

On the other hand, the ejection pressure from the gas ejector is 300 to 2000 mmA based on the internal pressure of the drum 1.
q is preferred. The amount of gas or normal air ejected is 0.
3 to 5.0 cc/cm2/sec is desirable. The air outlet may be a randomly formed circle or an appropriate shape. Further, the opening area ratio can also be varied in the width direction of the drum 1. The reduced pressure in the reduced pressure chamber 7 is 10 to 40 mmAq,
In particular, 20 to 30 mmAq is preferable. The tension applied to the web 3 is preferably 0.05 to 0.5 kg/cm. The distance G between the entrance edge 7a and the surface of the web 3 being conveyed is preferably 0.2 to 3.0 mm.

It is generally desirable to use a circular cross-sectional shape for the drum 1, but as long as an arc is formed from the entrance position of the web 3 to the bead formation position, the shape of other parts may be changed. Not necessarily limited.

The coating device used in the embodiment is a slide hopper type coating device, but is not limited to any type of coating device that forms beads based on the above-mentioned coating principle. A mold applicator can also be used. Of course, the present invention can also be applied in the case of one-layer coating or the case of coating three or more layers.

[0029] Examples of the web in the present invention include plastic films such as polyethylene terephthalate (PET) and cellulose triacetate, and paper.

(Example) Examples will be shown below to clarify the effects of the present invention. (Example 1) Using the coating apparatus shown in FIGS. 1 and 2, 1
Two layers of photosensitive material were applied to a 50 μm PET film. When the coating properties were examined with the above-mentioned intersection angle θ being 145 degrees, no horizontal unevenness or diagonal unevenness occurred.

(Comparative Example 1) As shown in FIGS. 5 and 6, the upper end surface of the side wall of the vacuum chamber and the outer surface of the blowing drum were separated from each other, and a web was passed between them. Other conditions are the same as in Example 1. As a result, when the gap L is 0.5 mm or less, the edge of the web comes into contact with the upper end surface of the side wall of the decompression chamber, and horizontal unevenness is often observed; conversely, when the gap L is 0.8 mm or more, , the occurrence of diagonal unevenness was mainly observed.

[0032]

As described above, according to the present invention, good coating properties can be obtained while taking advantage of the floating conveyance method.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of an example of the device of the present invention.

FIG. 2 is a view taken along the line IV-IV in FIG. 1;

FIG. 3 is a sectional view of another example.

FIG. 4 is a cross-sectional view of yet another example.

FIG. 5 is a cross-sectional view of an embodiment in which uneven coating is observed.

FIG. 6 is a sectional view of the main part thereof.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1... Hollow drum, 3... Web, 5... Coating device, 7... Decompression chamber, 7A... Side wall, 10, 11... Sealing material, θ...
Intersection angle, L1, L2... tangent.

Claims (1)

[Claims] Claim 1: While the web is levitated and conveyed while injecting gas to the surface opposite to the coating surface, the coating liquid flowing out from the coating device is applied onto the coating surface while forming beads. In the coating apparatus, a vacuum chamber is provided surrounding the bead forming region from the uncoated web area and in a direction opposite to the web conveyance direction, and is configured to reduce the pressure via the vacuum chamber, and further includes a vacuum chamber. 1. A web coating device, wherein the web passes through the web, and there is substantially no clearance between the open end surfaces of both side walls in the web conveyance direction and the opposing surface of the gas jet.