JP2000254567A - Method and apparatus for application - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent liquid storage generated on the back on the fringe side of a curtain membrane collision part and the reduce the thick application in both fringe parts of a substrate by sucking/removing a coating liquid applied on a support from the upstream side and downstream side of a collision part fringe side onto the support of a thin film liquid. SOLUTION: A coating liquid, while a curtain membrane 2 is being formed, is allowed to fall naturally from the tip 3 of a lip along an edge guide 4, to a continuously traveling web 5 by collision-corsslinking. An upstream side suction-removing apparatus 6 is installed on the upstream side of the edge guide 4 when a curtain membrane collision part 12 is made a base point to the traveling direction of the traveling web 5, and a lower side suction-removing apparatus 7 is installed on the downstream side. The coating liquid on the web 5 on the upstream side of the collision part 12 and a liquid bank is sucked continuously from the tip 8 of an upstream side suction part 8, and from the tip 9 of a lower side suction part 9, the fringe side thick application part of a substrate 11 on the web 5 on the downstream side of the collision part 12 is sucked/removed selectively and continuously.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the production of a silver halide photographic light-sensitive material, a magnetic recording material, a pressure- and heat-sensitive recording paper, and an ink-jet recording sheet, and relates to a continuously running belt-shaped support (hereinafter referred to as a web). ) And a thin film liquid (hereinafter, referred to as
It is called a curtain film. ) Is applied.

[0002]

2. Description of the Related Art As a multi-layer simultaneous coating method, a slide bead method or an extrusion method is generally known, but in recent years, a curtain coating method has been frequently used in accordance with a demand for high-speed coating. The curtain coating method is a method in which a curtain film is freely dropped and applied onto a continuously running web, and is disclosed as a basic technique in Japanese Patent Publication Nos. 49-24133 and 49-35447.

In the curtain coating method, in order to stably form a curtain film and regulate the coating width, Japanese Patent Publication No. 49-24133 is used.
In general, an edge guide as disclosed in Japanese Patent Application Laid-Open Publication No. H10-209,004 is used.

[0004] Since the edge guide liquid contact portion according to the disclosed method is a fixed wall, the impact force of the curtain film close to the fixed wall is reduced by the action of viscous resistance. The reduced impact force allows the air layer entrained in the web to easily penetrate between the coating solution and the web. The coating liquid whose cross-linking to the web is inhibited due to the presence of the entrained air becomes an excess liquid and forms a liquid pool near the rear edge of the curtain film collision portion at the lowermost edge guide. The liquid pool not only increases the drying load by forming a locally thick coating portion, but also deteriorates the product yield, so that the productivity is significantly reduced.

The use of an auxiliary liquid is exemplified in Japanese Patent Publication No. 49-35447 in order to reduce the viscous resistance of the edge guide liquid contact portion. While it is possible to reduce the viscous resistance in the vicinity of the edge guide wetted part by supplying a low viscosity auxiliary liquid such as water to the edge guide wetted part, the use of the auxiliary liquid reduces the formation of the liquid pool. There is a problem of promoting.

A method for avoiding the formation of such a liquid pool and reducing the viscous resistance in the vicinity of the liquid contact portion of the edge guide has been disclosed in Japanese Patent Publication No. Hei.
70507. According to the present disclosure, the method comprises the steps of providing a flushing liquid to the edge guide and extracting the liquid from the edge of the curtain film by a vacuum source connected near the curtain film collision point. The viscous resistance acting on the flushing liquid can be effectively reduced, and at the same time, the excess liquid generated by the supply of the flushing liquid can be extracted and removed.

However, in the liquid extracting means according to the present disclosure, even when the surplus liquid is extracted, even the coating liquid that is supposed to be a product is sucked and removed from the curtain film, so that the product yield may be reduced. Furthermore, since the extraction means is installed in a direction perpendicular to the curtain film falling direction,
The collision force on both sides of the curtain film during liquid extraction is reduced.
For this reason, although the viscous resistance in the vicinity of the edge guide liquid contact portion is reduced, there is a problem that entrained air is likely to invade on both sides of the curtain film collision portion.

On the other hand, various devices have been disclosed for selectively removing thick coating portions formed on both sides of a coating material. For example, Japanese Laid-Open Utility Model Publication No. Sho 61-15069 and Japanese Patent Application Laid-Open No.
-73579 and JP-A-7-299410.

[0009] However, in these disclosed methods, although the thick coating portion after coating can be selectively removed, since the thick coating portion removing device is installed downstream of the curtain film collision position, the use of the auxiliary liquid, Alternatively, thick coating may not be sufficiently suppressed depending on process conditions such as an increase in the coating amount.

[0010]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to allow a coating liquid to freely fall from a lip tip as a thin film liquid to continuously travel. In a curtain coating method for coating on a support to be coated, there is provided a coating method and a coating apparatus for preventing a liquid pool generated on the back side of an edge portion of a curtain film collision portion and reducing thick coating on both edges of a coating material. It is in.

[0011]

SUMMARY OF THE INVENTION The object of the present invention is to provide a curtain coating method in which a coating liquid is freely dropped from a lip tip as a thin film liquid material and is coated on a continuously running support. This is achieved by a coating method and a coating apparatus for sucking and removing a coating liquid applied on the support from the upstream side and the downstream side of the edge portion of the colliding portion.

The inventors of the present invention have paid attention to the fact that the liquid pool generated on the back side of the curtain film edge enlarges the thick coating on the edge side of the coating material and lowers the product yield.
By sucking and removing the coating liquid and the liquid pool applied on the support not only from the downstream side of the curtain film collision part edge side but also from the upstream side, there is no thick coating on the edge side of the coating material and extremely high product yield. They have found that good coatings can be obtained.

[0013]

FIG. 1 is a schematic perspective view showing an embodiment of the present invention. With the curtain head 1 described in JP-B-49-24133, the coating liquid is dropped freely while forming the curtain film 2 along the edge guide 4 from the tip 3 of the lip, and is impact-crosslinked and coated on the continuously running web 5. I do.

The curtain coating apparatus of the present invention includes an upstream suction removal device 6 upstream of the edge guide 4 when the curtain film collision portion 12 is a starting point with respect to the running direction of the continuously running web 5, A downstream suction removal device 7 is provided on the downstream side. Curtain film collision part 1 from upstream suction part tip 8
The application liquid and the liquid pool on the web 5 located on the upstream side of 2 are continuously sucked. From the distal end portion 9 of the downstream side suction portion, the edge side thick coating portion of the coating material 11 on the web 5 located on the downstream side of the curtain film collision portion 12 is selectively continuously suctioned and removed.

A metering pump (not shown) is connected to the diluting liquid injection manifold 16 and passes through the diluting liquid injection flow path 15 to join the application liquid sucked in the suction flow path 10. The application liquid diluted by a drain pump (not shown) connected to the suction manifold 13 is suctioned and drained. By aspirating and removing the coating liquid while diluting it, the coating liquid in the suction flow path 10 is washed and diluted, thereby preventing the application liquid from sticking to the drainage treatment tank in the pipe.

The diluent used in the suction and removal devices 6 and 7 of the present invention is warm water of 35 ° C. or more, and the flow rate of the diluent is 10 to 100 m.
It is preferably within the range of 1 / min, but is appropriately set according to the viscosity of the coating solution, the flow rate of the coating solution, and the like.

The material of the upstream suction removal device 6 and the downstream suction removal device 7 of the present invention is preferably stainless steel or titanium alloy from the viewpoint of corrosion resistance and processing accuracy, but is not limited thereto. Non-metallic materials can also be used.

In the present invention, it is desirable to apply a water-repellent treatment to the inner wall of the suction passage 10 of the upstream suction removal device 6 and the downstream suction removal device 7. As the water repellent material, any resin having water repellency to the coating liquid, such as a fluororesin, a polyacetal resin, a polyethylene resin, and a polystyrene resin, may be used.

In the present invention, the shape of the suction portions 8 and 9 of the suction and removal devices 6 and 7 is preferably a slit, but is not limited to this. For example, the suction portion of the upstream suction and removal device 6 is not limited thereto. Only the tip 8 has a nozzle shape,
Alternatively, it is also possible to form only the suction portion tip 9 of the downstream suction and removal device 7 in a nozzle shape, or to form both the suction portion tip 8 of the upstream suction and removal device 6 and the suction portion tip 9 of the downstream suction and removal device 7 in a nozzle shape. is there.

The edge guide used in practicing the present invention can be a flat plate type as shown in FIG. 1, but is not limited to this, and is not limited thereto. Edge guides such as described above can also be used as appropriate.

In FIG. 2, the inclination angle θ of the upstream suction portion tip 8 and the downstream suction portion tip 9 with respect to the web 5 is 30.
It is preferably in the range from 40 degrees to 80 degrees, and more preferably in the range from 40 degrees to 60 degrees.

In FIG. 2, a gap G is the vertical distance between the upstream suction portion tip 8 and the downstream suction portion tip 9 to the web 5. The preferred range of the gap G is 0.3 mm or more.
The gap G is 1.0 mm, and a more preferable range of the gap G is 0.4 mm to 0.6 mm.

As shown in FIG. 2, when the suction portions of the upstream suction removal device 6 and the downstream suction removal device 7 are slits, the slit clearance W is 0.2 mm to 1.0 m.
m, more preferably 0.4
mm to 0.6 mm.

[0024]

EXAMPLES In order to further clarify the effects of the present invention, examples will be described below in detail. Coating was performed according to the following conditions using a slide curtain coating device described in JP-B-49-24133. Operating conditions Web: 140 μm thick polyethylene resin coated paper Web width: 1500 mm Application width: 1490 mm Curtain height: 80 mm Application speed: 250 m / min

Coating liquid: Upper layer: protective layer Viscosity: 40 cP, surface tension: 25 dyne / cm (37 ° C.) Coating amount: 10 g / m ² Lower layer: silver halide emulsion layer Viscosity: 60 cP, surface tension: 30 dyne / cm (37 ° C) Coating amount: 40 g / m ²

Example 1 The suction and removal devices 6 and 7 shown in FIGS. 1 and 2 were installed on the upstream and downstream sides of the curtain film collision section 12. The installation conditions are as follows: a gap G of 0.4 mm, an inclination angle θ of 60 degrees, a slit clearance W of 0.5 mm, and a slit opening width of 10 mm.
mm. A suction pump (not shown) connected to the suction manifold 13 had a suction amount of 5 Nm ² / min (air) and a suction pressure of −2500 mmAq. The diluent is warm water of 50 ° C., and the diluent flow rate is 80 ml / min.
And Here, the coating edge thick coating rate described in Table 1 = ((A
−B) / B) × 100, where, as shown in FIG.
Is the maximum thickness of the edge of the coating 11 and B is the thickness of the normal portion of the coating 11. In addition, the film thickness was measured by observing the cross section of the coating material 11 with an electron microscope. In Table 1, the presence or absence of liquid pool formation was determined by visual observation. Edge loss is less than product quality standards.
1 is a value measured from the edge to the center. As shown in Table 1, a coating product was obtained without formation of a liquid pool and with very little edge loss while preventing the formation of a thick coating.

Example 2 Example 2 was carried out under the same conditions as in Example 1 except that the auxiliary liquid was supplied from the top of the edge guide. Pure water at 40 ° C. was used as an auxiliary liquid and supplied at a flow rate of 60 ml / min. From the results shown in Table 1, even when the auxiliary liquid was used, a coating material having a good yield was obtained without formation of a liquid pool and formation of a thick coating portion.

Comparative Example 1 An edge guide (rod type) described in JP-B-49-24133 was used. In the conventional type edge guide, as shown in Table 1, the thickness of the edge thick coating portion is about twice the film thickness of the normal portion, and not only the drying load is increased, but also the blocking of the wound product is observed. Was. In addition, the occurrence of the liquid pool caused a large edge loss.

Comparative Example 2 The suction removing device 6 was installed only on the upstream side of the curtain film collision section 12. The installation conditions are the same as in the first embodiment. The installation of the suction and removal device 6 on the upstream side prevented the formation of a liquid pool, but the suction and removal device 7 was not installed on the downstream side, so that the formation of thick edge coating was not suppressed.

Comparative Example 3 The suction removing device 7 was installed only on the downstream side of the curtain film collision section 12. The installation conditions are the same as in the first embodiment. Comparative Example 2
On the contrary, since the suction removing device 6 is not installed on the upstream side, the generation of the liquid pool cannot be avoided, and the edge loss becomes large. However, since the suction-removal device 7 was installed on the downstream side, the edge thick coating was suppressed as compared with Comparative Examples 1 and 2.

[0031]

[Table 1]

[0032]

According to the present invention, in a curtain coating method in which a coating liquid is freely dropped from a lip tip as a thin film liquid and is coated on a continuously running support, a liquid pool generated on the back side of the edge of the curtain film collision portion is provided. Thus, it is possible to provide a coating method and a coating apparatus which can prevent the occurrence of thick coating on both edges of the coating material.

[Brief description of the drawings]

FIG. 1 is a schematic configuration perspective view of a curtain coating device according to the present invention.

FIG. 2 is a partially enlarged cross-sectional view of the curtain coating device of the present invention.

FIG. 3 is a cross-sectional view of a coating material.

[Description of Signs] 1 curtain head 2 curtain film 3 lip tip 4 edge guide 5 web 6 upstream suction removal device 7 downstream suction removal device θ inclination angle G gap W slit clearance A maximum coating thickness at coating edge B normal part Film thickness

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G11B 5/84 G11B 5/84 Z F term (Reference) 2H023 EA04 4D075 AC14 AC84 CA48 DA04 DB18 DB31 DC24 DC28 EA45 4F041 AA12 CA04 CA22 CA25 4F042 AA22 BA27 DD03 DD04 5D112 CC01 CC02

Claims (2)

[Claims] 1. A curtain coating method in which a coating liquid is freely dropped from a lip tip as a thin film liquid material and is coated on a continuously running support. A coating method, wherein a coating liquid applied on the support is removed by suction from an upstream side and a downstream side. 2. A curtain coating apparatus in which a coating liquid is freely dropped from a lip tip as a thin film liquid material and is coated on a continuously running support. A coating apparatus comprising suction means on an upstream side and a downstream side for removing a coating solution applied on the support.