JP2002361148A - Application apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make the coating thickness distribution sufficiently even in the width direction of a web in extrusion type application and particularly to make the coating thickness distribution sufficiently even in the width direction of a web even under conditions that the slit gap is narrowed to suppress coating defects caused following high speed thin layer application. SOLUTION: To control the width of coating applied to a web 12, the thickness of spacers 26, 26 to be inserted in both end parts of a slit 20 of a coating head 14 is made thicker than the gap of the slit 20 and the thickness of the spacer 26 is controlled so as to be the thickness of the coating film applied to the web 12.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for applying a coating liquid such as a photographic photosensitive liquid, a magnetic liquid, a solvent coating or the like to a running long flexible support (hereinafter referred to as "web") by an extrusion coating method. The present invention relates to a coating device for coating.

[0002]

2. Description of the Related Art An extrusion type coating apparatus is often used as a coating apparatus for manufacturing a photographic film, a magnetic recording medium, etc. by applying a coating liquid such as a photographic photosensitive liquid or a magnetic liquid to a continuously running web. I have. The coating apparatus extrudes one or a plurality of coating liquids from the slits of the coating head and applies the liquid to the web while the continuously running web and the tip of the coating head are close to each other. In addition, in this extrusion type coating apparatus, it is general that the coating width applied to the web is regulated by spacers inserted at both ends of the slit.

As the type of the extrusion type coating apparatus, there are a single-layer coating apparatus described in Japanese Patent Publication No. 5-8065, a multi-layer coating apparatus described in Japanese Patent Publication No. 6-77712, or a patent application. As described in Japanese Patent No. 2942938, a precoat liquid mainly containing a solvent of a coating liquid or the like is preliminarily applied to a coating surface of a web, and then a coating liquid such as a photographic photosensitive liquid or a magnetic liquid is applied by a coating apparatus. Some are applied.

[0004]

In recent years, high-speed thin-layer coating has been performed on photographic photosensitive liquids and magnetic recording media in accordance with improvements in performance and productivity. When is increased, the entrained air entrained in the web is mixed into the coating film, and coating defects such as uniform pitch streaks tend to occur. Measures to suppress this coating defect are:
It is effective to increase the dynamic pressure (inertia) of the coating liquid by reducing the slit gap size of the coating head.

However, in any of the extrusion type coating apparatuses described above, when the gap size of the slit is reduced, the liquid pressure in the slit increases, the coating head is deformed, and the slit gap size is reduced. There is a problem that the gap becomes wider than the set gap size. Therefore, even if coating defects due to equal pitch streaks or the like can be suppressed by reducing the slit gap size, there is a problem that the coating thickness distribution in the web width direction becomes non-uniform.

As a measure to make the coating thickness distribution in the web width direction uniform in an extrusion type coating apparatus, Japanese Patent Application Laid-Open No. 62-152568 discloses a side surface inside a slit of a flat regulating member inserted at both ends of the slit. It is disclosed that the slit width is reduced so that the slit width becomes shorter as it approaches the slit discharge port. Further, Japanese Unexamined Patent Application Publication No. 11-207236
Japanese Patent Application Laid-Open Publication No. H11-163873 discloses that slit gap regulating members thinner than the gap dimension of the slit are inserted into both ends of the slit.

However, Japanese Patent Application Laid-Open No. 62-152568
Japanese Patent Application Laid-Open No. H11-207236 discloses a coating apparatus in which the gap between slits is narrowed to suppress coating defects caused by high-speed thin-layer coating. There is a disadvantage that it cannot be made uniform.

Accordingly, there is a demand for an extrusion-type coating apparatus which can suppress coating defects such as uniform pitch streaks and the like caused by high-speed thin-layer coating and can make the coating thickness distribution uniform in the web width direction.

The present invention has been made in view of such circumstances, and makes it possible to uniform the coating thickness distribution in the web width direction in extrusion-type coating, and to suppress coating defects particularly caused by high-speed thin-layer coating. Therefore, an object of the present invention is to provide a coating apparatus which can make the coating thickness distribution uniform in the web width direction even under the condition that the slit gap size is narrowed.

[0010]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a method in which a flexible support which continuously travels and a tip end of a coating head are brought close to each other through a slit of the coating head. Or a coating apparatus for extruding a plurality of coating liquids and applying the liquid to the flexible support, wherein the coating width for applying to the flexible support is regulated by spacers inserted at both ends of the slit. The thickness of the spacer is made thicker than the gap size of the slit so that the center of the slit in the width direction of the flexible support becomes a gap size smaller than both ends, and the coating liquid flows from the slit. When extruding, the central portion of the slit is expanded by a hydraulic pressure so that a uniform gap dimension in the width direction of the flexible support is substantially equal to the thickness of the spacer.

The present invention utilizes the phenomenon that the central portion of the slit expands due to the liquid pressure when the coating liquid is extruded when the slit gap size is small, and is inserted into both ends of the slit of the coating head. The thickness of the spacer
It was made thicker than the gap size of the slit. Thereby, the shape of the slit is such that when the coating liquid is not flowing through the slit, the gap dimension is gradually narrowed from the ends of the slit toward the center of the slit, and when the coating liquid flows through the slit, the slit is expanded by the liquid pressure. The gap size in the slit width direction becomes substantially equal. Therefore, if the thickness of the spacer is set to the thickness of the coating film applied to the flexible support, the gap dimension in the slit width direction becomes substantially equal to the gap dimension corresponding to the spacer thickness width. Thereby, a coating film having a desired thickness according to the thickness of the spacer can be applied to the web,
In addition, the application pressure distribution in the web width direction can be made uniform.

In a preferred embodiment of the present invention, the thickness of the spacer is 2% or more and 5% or less of the slit gap size.
Thickness is set within the following range, and the slit gap size is set to 20 to 20
It is preferable to set the range to 0 μm.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of a coating apparatus according to the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 is a conceptual diagram of a coating apparatus according to the present invention in which a single layer is coated on a web from one slit.
FIG. 2 is a side sectional view of the coating apparatus, as shown in FIG.
The coating apparatus 10 mainly includes a web 12 that runs continuously in the direction of the arrow, an extrusion-type coating head 14 that applies the coating liquid A to the web 12, and a spacer 26 that controls the coating width that is applied to the web. You.

The coating head 14 has a doctor edge 16
It is configured by assembling two dividable blocks consisting of a back edge portion 18 and a doctor edge portion 16.
On the downstream side in the web running direction from the exit of the slit 20, the back edge portion 18 is located on the upstream side, and the doctor edge portion 16 and the edge surface of the back edge portion 18 are opposed to each other in a state in which the edge surfaces of the continuously running web 12 are close to each other. Is done. Inside the coating head 14, a cylindrical pocket portion 22 is formed along the width direction of the web 12. Openings at both ends of the pocket portion 22 are closed by side plates (not shown) provided on both side surfaces of the coating head 14. Then, the coating liquid A is supplied to the pocket portion 22 by connecting a liquid supply system 24 (see FIG. 2) for the coating liquid A to one of the side plates. As a method of supplying the coating liquid A to the pocket portion 22, in addition to closing the other end side of the pocket portion 22 described above and supplying it from one side, supplying the coating liquid A from one side of the pocket portion 22 to the other end There is a type that is pulled out from the side and a type that is supplied from the central portion of the pocket portion 22 and diverted to both sides. Either type may be applied. An arrow 19 in FIG. 1 indicates the flow of the coating liquid A. The liquid supply system 24 may be any as long as it can continuously supply the coating liquid A to the pocket portion 22 with a constant liquid amount.

The slit 20 is formed in the pocket 2
This is a narrow flow path connecting the edge 2 and the edge surface 21, and extends in the web width direction, and the thickness of the coating film applied to the web 12 is substantially determined by the gap size of the slit 20. In addition, the flow path length of the slit 20 in the web direction is
It is appropriately set in consideration of application conditions such as the liquid composition, physical properties, supply flow rate, and supply liquid pressure of the application liquid A.

In the coating apparatus 10 configured as described above, the coating liquid A such as a photographic photosensitive liquid and a magnetic liquid supplied from the liquid supply system 24 to the pocket section 22 of the coating head 14 is applied to the pocket section 2.
After the flow is spread at step 2, the liquid is discharged from the tip of the coating head while moving up the slit 20. The discharged coating liquid A forms a kind of bead between the web 12 running close to the tip of the coating head 14 and the edge surface 21 while forming a kind of bead.
2 is applied. Thus, a single-layer coating film is formed on the web 12.

In the coating apparatus 10, the width of the coating applied to the web 12 is regulated by spacers 26 inserted at both ends of the slit 20. In the present invention, the thickness of the spacer 26 is made larger than the gap size of the slit 20 so that the center of the slit in the width direction of the web 12 has a gap size smaller than both end portions. When the coating solution A is extruded from the substrate, the central portion of the slit is expanded by the liquid pressure so that the gap size is approximately the same as the thickness of the spacer 26 and is uniform in the web width direction.

FIG. 3 is a view of the coating head 14 according to the present invention as viewed from the web 12 side. The spacer 2 having a thickness larger than the gap size of the slit 20 and the thickness of the coating film is set.
6 are arranged at both ends of the slit 20. FIG.
Is a configuration in which spacers 26 having the same thickness as the gap dimension of the slit 20 set to be the thickness of the coating film formed on the web 12 are arranged at both ends of the slit 20, which is a configuration of a so-called conventional coating apparatus. .

As can be seen from FIG. 3, by setting the thickness of the spacer 26 inserted at both ends of the slit of the coating head 14 to be larger than the gap dimension of the slit 20, when the coating liquid A does not flow through the slit 20, As shown by the solid line, a narrow slit is formed in which the gap dimension gradually narrows from both ends of the slit where the spacer 26 is inserted to the center of the slit. When the coating liquid A is supplied to the medium-slit slit, as shown by the imaginary line, the slit central portion becomes wider than both ends due to the liquid pressure, and the gap dimension in the slit width direction becomes uniform. Accordingly, if the thickness of the spacer 26 is set to the thickness of the coating film applied to the web 12, the gap dimension in the slit width direction becomes equal to the gap dimension corresponding to the thickness of the spacer 26. As a result, the web 12
In addition, a coating film having a desired thickness corresponding to the spacer thickness can be applied, and the coating thickness distribution in the web width direction can be made uniform. Accordingly, in order to suppress coating defects such as equi-pitch streaks that occur with high-speed thin-layer coating, the gap size of the slit 20 is reduced and the dynamic pressure (inertia) of the coating liquid A is reduced.
If the present invention is applied under the condition of increasing the number of coatings, coating defects such as uniform pitch streaks can be suppressed, and the coating thickness distribution in the web width direction can be made sufficiently uniform.

On the other hand, in the case of FIG. 4, when the coating liquid A does not flow through the slit 20, the gap size in the slit width direction becomes uniform as shown by the imaginary line.
When the coating liquid A is supplied to the slit, as shown by the solid line, the liquid pressure causes the central portion of the slit to be larger than both end portions. As a result, the coating thickness distribution of the coating film applied on the web 12 in the web width direction becomes non-uniform. The degree of this non-uniformity is determined by controlling the slit 20
The smaller the is, the larger it becomes.

In the present invention, the thickness increase ratio for making the thickness of the spacer 26 larger than the gap size of the slit 20 is as follows.
It is preferable that the thickness is 2% or more than the gap size of the slit 20, and the upper limit is 5% or less. This is because when the thickness increase ratio is less than 2%, it is difficult to form a medium-thin slit. If the thickness increase ratio exceeds 5%, the difference between the gap size at both ends of the slit and the gap size at the center of the slit becomes too large, and the coating solution A
, It is difficult to make the gap size in the slit width direction uniform.

The gap size of the slit 20 in the present invention is 20 to 2 when the coating solution A is not flowing.
It is preferably in the range of 00 μm. This is because the smaller the slit gap size, the higher the dynamic pressure (inertia) of the coating liquid A. However, if the gap size of the slit 20 is less than 20 μm, the gap size at the center of the slit becomes narrower when a narrow slit is formed. Too much. When the gap size of the slit 20 exceeds 200 μm, it is difficult to obtain a sufficient dynamic pressure (inertia) of the coating liquid A to suppress coating defects such as a uniform pitch streak failure.

Furthermore, since the thickness of the coating film applied to the web 12 corresponds to the thickness of the spacer 26, if the thickness of the spacer 26 is within the range of 2% or more and 5% or less of the slit gap size. By changing the thickness of the spacer 26, the thickness of the coating film applied to the web 12 can be changed. Therefore, if a plurality of types of spacers 26 having different thicknesses are prepared, the gap size of the slit 20 can be changed only by replacing the spacer 26 without adjusting the gap size of the slit 20 by adjusting the assembly of the doctor edge portion and the back edge portion. This is convenient because you can fine-tune

Further, in the embodiment of the present invention, an example in which the coating head 14 having one slit 20 applies a single layer to the web 12 has been described, but the application is not limited to the single layer application. That is, the coating head having the plurality of slits 20 is also formed so that the thickness of the spacer 26 is larger than the gap dimension of the slit 20 and the thickness of the spacer 26 becomes the thickness of the coating film applied to the web 12. You can do so. Further, the present invention can be applied to a coating apparatus of a type in which a precoat liquid mainly containing a solvent or the like of the coating liquid A is previously applied to the coating surface of the web 12 and then the coating liquid A is applied by a coating head. .

[0026]

As described above, according to the coating apparatus of the present invention, it is possible to sufficiently uniform the coating thickness distribution in the web width direction in the extrusion type coating. The coating thickness distribution in the web width direction can be made uniform even under conditions in which the slit gap size is reduced in order to suppress coating defects caused by the coating.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram of a coating apparatus of the present invention.

FIG. 2 is a side sectional view of a coating head device.

FIG. 3 is a view of a coating head of the coating apparatus of the present invention as viewed from a web side.

FIG. 4 is a view of a coating head of a conventional coating apparatus viewed from a web side.

[Explanation of symbols]

10: coating device, 12: web, 14: coating head, 1
6 ... Doctor edge, 18 ... Back edge, 20 ...
Slit, 21 ... edge surface, 22 ... pocket, 24 ...
Liquid supply system, 26: spacer, A: coating liquid

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Hideaki Takekuma 1-2-1 Ogimachi, Odawara-shi, Kanagawa F-Term in Fuji Photo Film Co., Ltd. (Reference) 2H023 EA01 4F041 AA12 AB01 CA02 CA12 5D112 AA05 AA22 CC03 CC08

Claims (1)

[Claims] 1. A method in which one or a plurality of coating liquids are extruded from a slit of the coating head and coated on the flexible support in a state where the continuously running flexible support and the tip of the coating head are close to each other. A coating device for controlling the width of coating applied to the flexible support by spacers inserted at both ends of the slit, wherein the thickness of the spacer is larger than the gap size of the slit. The central portion of the slit in the width direction of the flexible support is made to have a smaller gap size than both end portions, and when extruding the coating liquid from the slit, the central portion of the slit is expanded by the liquid pressure to form the spacer. A coating apparatus characterized in that a uniform gap dimension is provided in the width direction of the flexible support at substantially the same thickness as the thickness.