JP5098181B2 - Application method - Google Patents

Description

  The present invention relates to a coating method, in particular, a photographic photosensitive emulsifier, a magnetic material solution, a coating solution for an optical thin film that exhibits functions such as antireflection performance, and the like, such as plastic film, paper, and metal foil. The present invention relates to a coating method for producing a sheet-like material which is applied to a support (hereinafter referred to as a base material) and exhibits high functionality.

  There are two types of processes for producing sheet-like products that exhibit high functionality: dry processes such as vapor deposition and wet processes such as coating. In recent years, the so-called “pre-weighing type” coating method using a die head has been used in the wet process. Among the coating methods that use the die head, in the extrusion method, the die head is pressed directly onto the traveling substrate and applied, and the tip of the die head is applied close to the substrate that is wound around the backup roll and conveyed. There is a way to do it.

There is a problem of “beginning of coating” as a part that greatly affects the yield in production by the coating method using this die head. This is a problem in which a portion that is not recognized as a product occurs between the time when the coating solution is cross-linked to the substrate to be traveled and the state where the coating solution is in a steady coating state (the coating state that is recognized as a product). This contributes to the improvement of the yield. Therefore, various means have been studied so far.
In particular, when a die head is used for the purpose of speeding up, the problem becomes serious because loss increases.

  Patent Document 1 discloses a method in which a die head is brought close to a backup roll at a speed of 50 to 300 μm / s and starts to be applied at a higher degree of reduced pressure than in a normal state. In this method, depending on the conditions, it is possible to start coating as intended, but since there is no regulation of the degree of vacuum, the coating liquid may not be applied well to the substrate even when a higher degree of vacuum is set than in the normal state. is there.

  Furthermore, although the method described in Patent Document 2 may be successful depending on conditions, the coating solution may not be applied well to the substrate when the steady coating position is away from the substrate surface.

Prior art documents are shown below.
Japanese Patent Laid-Open No. 1-213641 JP 2004-141806 A

  Therefore, in the method of applying the die head close to the substrate to be transported, it is necessary to improve the yield by shortening the distance from the start of coating to the steady portion.

The invention according to claim 1 includes a step of bringing the tip of the die head close to the substrate to be conveyed while coating the coating liquid, a step of separating the tip of the die head that has been brought close to the substrate from the substrate, and the tip of the substrate and the die head. A step of applying while maintaining a constant distance (steady application position), and applying the pressure while reducing the pressure in a reduced pressure chamber. The amount of coating solution applied from the die head during the step of bringing the tip of the die head close to the substrate and the step of bringing the tip of the die head close to the substrate and the step of separating the tip of the die head close to the substrate away from the substrate. However, it is 5-50 from the coating amount of the coating liquid coated from the die head during the coating process while keeping the substrate and the tip of the die head at a constant distance (steady coating position). In the step of bringing the die head tip close to the base material and the step of separating the die head tip close to the base material from the base material, the die head tip is brought close to the base material and then brought close to the base material for 0.5 to 5 seconds. And holding the tip of the die head close to the base material away from the base material .

  According to a second aspect of the present invention, the degree of pressure reduction in the chamber during the step of bringing the die head tip close to the substrate and the step of separating the die head tip brought close to the substrate from the substrate is constant between the substrate and the die head tip. 2. The coating method according to claim 1, which is 0.1 to 0.5 kPa higher than the degree of vacuum in the chamber during the coating process while maintaining the distance (steady coating position).

  In the coating method of the present invention, the steady application state can be efficiently created by dividing the timing for reliably performing the crosslinking of the coating solution onto the substrate and the timing for creating the steady coating state separately. . Moreover, there exists an effect which can perform the bridge | crosslinking of the coating liquid to a base material more reliably.

  The die head is installed so as to face the substrate to be conveyed, and does not depend on the shape or the installation angle of the die head. In the so-called preparation stage, the die head stands by at a position far away from the substrate, and approaches the substrate surface as the application starts. The start of coating in the present invention refers to the time when the die head is brought close to the substrate as described above. The approaching mechanism is such that the moving table is moved on the LM guide with high accuracy by a servo motor or hydraulic pressure. The moving speed is preferably about 1 to 30 mm / s, but the present invention does not depend on the speed.

  FIG. 1 shows an example of an ideal coating start sequence.

  First, the gap distance L1 between the substrate surface and the tip of the die head is reduced to 60 μm or less. At this time, the coating liquid is applied from the die head. If this distance is too large, subsequent crosslinking will not be successful, and if it is too small, dust may be generated by rubbing the substrate surface and the tip of the die head.

  It is necessary to install a decompression chamber on the upstream side with respect to the substrate flow direction of the die head and to decompress the upstream side at the moment when the coating solution comes into contact with the substrate. In order to reduce the pressure, air in a vacuum chamber (not shown) is sucked out by a blower. Therefore, the die head is moved while operating the pressure reducing blower in advance. The rotational speed of the blower at this time is usually matched with the steady-state value, but it may be difficult to bridge once the gap is reduced. Therefore, it is preferable to increase the degree of pressure reduction at a higher rotational speed. . That is, it is preferable to set the pressure reduction degree P2 when the die head tips are close to each other to be higher than the pressure reduction degree P1 in the steady application state. The degree is preferably 0.1 to 0.5 kPa higher than the degree of decompression. If this value is too small, the effect will be lost, and if it is too large, it will be drawn into reduced pressure and liquid crosslinking will not be possible.

Further, the coating amount Q2 of the coating liquid when the tip of the die head is brought close may be set higher than the coating amount Q1 of the coating liquid in a steady coating state. Setting the coating amount to a higher value may be performed both for increasing the degree of decompression, or increasing only the coating amount. Furthermore, it is desirable that the coating amount Q2 at that time is 5 to 50% higher than the coating amount Q1 in a steady coating state. If this value is too small, there is no effect, and if it is too large, there is no hindrance to reliable crosslinking, but the coating solution is unnecessarily flown, which is not preferable.
Here, two solid lines are drawn in the graph of the degree of decompression and the coating amount in FIG. 1 when the die head tip is brought close to the substrate and the die head tip brought close to the substrate is separated from the substrate. The degree of decompression and the amount of coating in the chamber at the time, and the degree of decompression and the amount of coating in the chamber during the coating process while maintaining the substrate and the tip of the die head at a constant distance (steady coating position) must change. This is because an ideal coating film may be formed.

  After the liquid crosslinking, the gap distance between the tip of the die head and the substrate surface is extended to the steady application position L2. At this time, the degree of reduced pressure and the coating amount are changed to a steady application state in conjunction with the change in the gap distance between the tip of the die head and the substrate surface. The moving timing t2 is preferably within 0.5 to 5 seconds from the time t1 when the tip of the die head approaches the substrate surface. If this time is too short, reliable liquid crosslinking to the substrate may be difficult, and if it is too long, there is a problem in terms of yield.

  In order to execute the above movement more accurately, a sequence is used to control the movement of the die head, the operation status of the decompression blower at that time, and the coating amount of the coating liquid dispensed from the die head. preferable.

  Examples of the coating solution used in the present invention include methyl acetate, ethyl acetate, butyl acetate, propyl acetate, methyl ethyl ketone, methyl isobutyl ketone, acetone, methanol, ethanol, propanol, isopropyl alcohol, ethylene glycol, ethylene glycol monomethyl ether, ethylene glycol monomethyl. A coating solution using ether acetate, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, toluene, dioxolane, cyclohexanol, cyclohexanone, cyclohexane or water as a diluting solvent can be considered, but is not limited thereto. The effect does not depend on the physical properties of the coating solution. Although there is no dependence on the wet film thickness to be applied, it is more effective to apply a thin film having a wet film thickness of 20 μm or less.

Using a polyethylene terephthalate substrate with a width of 650 mm, and using an extrusion type die head with a width of 640 mm, a 50 wt% acrylic UV curable resin coating solution containing methyl ethyl ketone (MEK) and methyl acetate as a diluent solvent has a wet film thickness of 10 μm. It was applied at a speed of 50 m / min. The coating solution has a viscosity of 4 mPas and a surface tension of 25 mN / m.
The gap L2 between the tip of the die head at the steady application position and the substrate surface is 75 μm, the degree of vacuum P1 is 1.5 KPa, and the coating amount Q1 is 320 cc / min.

  Here, when the tip of the die head is close to the substrate surface, the gap L1 between the tip of the die head and the substrate is 60 μm, the degree of vacuum P2 is 1.6 KPa, the coating amount Q2 is 340 cc / min, and the tip of the die head is the substrate The sample of Example 1 was obtained by setting the time t2-t1 close to the surface to 0.5 seconds.

  Under the same conditions as in Example 1, P2 was set to 1.5 KPa, and the sample of Example 2 was obtained.

  Under the same conditions as in Example 1, Q2 was set to 320 cc / min, and the sample of Example 3 was obtained.

  Under the same conditions as in Example 1, P2 was set to 1.5 KPa, Q2 was set to 320 cc / min, and the sample of Example 4 was obtained.

<Comparative Example 1>
Under the same conditions as in Example 1, t2-t1 was set to 0 second to obtain a sample of Comparative Example 1.

<Comparative example 2>
Under the same conditions as in Example 1, L1 was 75 μm, the degree of vacuum P2 was 1.5 KPa, the liquid flow rate Q2 was 320 cc / min, and a sample of Comparative Example 2 was obtained.

<Comparative Example 3>
Under the same conditions as in Example 1, L1 was 90 μm, the degree of vacuum P2 was 1.5 KPa, the liquid flow rate Q2 was 320 cc / min, and a sample of Comparative Example 3 was obtained.

  As described above, the coating state was confirmed by changing the parameters. The results are shown in Table 1. Here, the number of times that the coating surface was successfully applied in the width direction when n = 10 was recorded.

From the above results, the state of the start of coating is improved by narrowing the gap between the tip of the die head and the surface of the substrate, and until the start of coating and the tip of the die head that is close to the substrate starts to move away to the steady coating position. It can be seen that the probability is further increased by increasing the coating amount or increasing the degree of decompression. It can also be seen that the probability is increased by keeping the die head tip close to the substrate and then keeping the state close to 0.5 seconds or more.

  The present invention relates to a coating method, and in particular, a photographic photosensitive emulsifier, a magnetic material solution, a coating solution for an optical thin film that exhibits functions such as antireflection performance, and the like on a substrate such as a plastic film, paper, or metal foil. It is effective when applied to produce a sheet-like material that exhibits high functionality.

It is the figure which showed the sequence of the ideal coating start.

Explanation of symbols

L1 Gap distance L2 between the die head tip and the substrate surface when the tip of the die head comes close to the substrate surface L2 Gap distance P1 between the die head tip and the substrate surface in a steady coating state P1 Decompression degree P2 in a steady coating state Degree of decompression Q1 until the tip of the die head close to the substrate starts to move to the steady coating position Q1 Coating amount Q2 in the steady coating state Steady coating of the die head tip close to the substrate from the start of coating Coating amount t1 until it starts to move to the position t1 Time when the tip of the die head comes close to the surface of the substrate t2 Time when the tip of the die head starts to move away from the steady coating position

Claims (2)

A step of bringing the tip of the die head close to the substrate to be conveyed while coating the coating liquid;
A step of separating the tip of the die head close to the substrate from the substrate;
Applying while keeping the substrate and die head tip at a fixed distance (steady application position),
Have
And in the coating method of applying while reducing the pressure in the vacuum chamber,
The step of bringing the tip of the die head close to the substrate is brought close to the gap distance of 60 μm or less between the substrate and the tip of the die head,
The amount of coating liquid applied from the die head during the step of bringing the tip of the die head close to the substrate and the step of separating the tip of the die head close to the substrate from the substrate is a constant distance between the substrate and the tip of the die head ( 5 to 50% higher than the application amount of the application liquid applied from the die head during the application process while maintaining the constant application position)
In the step of bringing the die head tip close to the substrate and the step of separating the die head tip brought close to the substrate from the substrate,
An application method comprising: bringing a die head tip close to a substrate, holding the state of being brought close to 0.5 to 5 seconds, and then separating the die head tip brought close to the substrate from the substrate. The degree of pressure reduction in the chamber during the step of bringing the die head tip close to the base material and the step of separating the die head tip close to the base material from the base material is a constant distance between the base material and the die head tip (steady coating position) The coating method according to claim 1, wherein the coating pressure is higher by 0.1 to 0.5 kPa than the degree of vacuum in the chamber during the coating step.

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