JP4165778B2 - Coating apparatus and coating method using the same - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention belongs to the technical field of applying a coating solution to the surface of a substrate, and in particular, a low-viscosity, thin-film coating solution that can be used for gravure direct coating is applied to the substrate surface using an extrusion type slot die. Regarding technology.
[0002]
[Prior art]
For example, in a thermal transfer printer such as melt transfer or sublimation transfer, as shown in FIG. 1, yellow (Y), magenta (M), cyan (C), and black (Bk) ink is applied to a base material such as a polyester film. Is used in a pattern. In addition to the four colors of ink, there are cases where ink for forming a receiving layer or an adhesive layer is interposed therebetween. Such an ink ribbon is manufactured by applying a multicolor coating liquid or the like in a repeated pattern to a continuously running substrate by gravure coating.
[0003]
[Problems to be solved by the invention]
Pattern application by gravure coating described in the prior art is a relatively fast and highly efficient method, but there are many defects due to the coating method, and in multi-color pattern application, the number of colors increases. Incidence increases and yield decreases. Further, even if the processing accuracy of the component parts constituting the coating apparatus is improved, there is a limit, and it is difficult to avoid the generation of defective plates or doctors, cell eyes or uneven coating.
[0004]
The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a coating apparatus that can perform pattern coating with a plurality of coating liquids with high quality. .
[0005]
[Means for Solving the Problems]
In order to achieve the above object, the coating apparatus of the present invention comprises at least two or more slots for discharging different coating liquids from the tip portion by switching , and among the plurality of lips forming each slot. It has an extrusion die head in which the first lip on the upstream side protrudes, the tip surface of the remaining lip is flush, and the tip side of the flow path in each slot is narrowed.
[0006]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 2 is a cross-sectional view showing an example of a die head in the coating apparatus according to the present invention. The die head shown in the figure is a two-liquid discharge type, 1 is an upstream lip, 2 is a downstream lip, 3 is a central lip, and the first color from the first slot 4 between the upstream lip 1 and the central lip 3. The second color coating liquid is discharged from the second slot 5 between the central lip 3 and the downstream lip 2. FIGS. 3A and 3B show a state in which the first color coating liquid A and the second color coating liquid B are discharged and applied to the substrate 6, respectively.
[0007]
The die head of FIG. 2 is formed such that the upstream lip 1 protrudes from the other lips, and the distal end surfaces of the downstream lip 2 and the central lip 3 are formed in the same arc shape and flush with each other. As described above, the tip surfaces of the lips other than the upstream lip 1 are made arcuate and flush with each other, so that turbulence such as vortices does not occur in the coating liquid flowing in the liquid pool. Further, the first slot 4 and the second slot 5 are formed in such a direction that they join at the tip portions thereof, and each is formed so that the tip side of the flow path becomes narrow. By setting the gap on the tip side to 50 times or less of the coating film thickness, the entrained vortex at the opening of the non-ejection side slot can be minimized. The angle [theta] of the central lip 3 is preferably about 15 to 90 [deg.] For convenience of processing.
[0008]
In the example shown in FIG. 2, the lips other than the upstream lip 1 are two lips, the downstream lip 2 and the central lip 3, but it is also possible to form more lips and increase the number of slots to 3-4. It is.
[0009]
Here, for example, as in the ink ribbon R shown in FIG. 1, in order to apply four colors of ink in a repeated pattern, a coating apparatus having a die head in which four slots are formed may be used. Alternatively, even if two coating devices having a two-liquid discharge type die head as shown in FIG. 2 are arranged side by side and the two are synchronized to apply two colors at a time, four colors of ink are applied in a repeated pattern. can do.
[0010]
【Example】
The following two types of coating solutions were alternately applied to a PET film (thickness: 4.5 μm, width: 500 mm) by a coating apparatus having a die head as shown in FIG. The application conditions are tension: 2.5 to 10 kg, line speed: 50 to 150 m / min, wet thickness: 10 μm.
[0011]
[Coating liquid A]
Medium solution: vinyl acetate copolymer + methyl ethyl ketone (viscosity 10 cp)
Coloring dye: Oil red [Coating solution B]
Medium solution: vinyl acetate copolymer + methyl ethyl ketone (viscosity 20 cp)
Coloring dye: None [0012]
As a result, it was possible to apply the pattern without mixing the two color coating liquids, and no unevenness or unevenness was generated, and the quality was good compared to the gravure coating.
[0013]
【The invention's effect】
As described above, according to the present invention, in a coating apparatus having an extrusion-type die head that intermittently coats two or more coating liquids, mixing at the time of liquid switching is minimized by devising a lip shape. Therefore, pattern coating of a plurality of coating liquids can be performed with high quality.
[Brief description of the drawings]
FIG. 1 is a perspective view illustrating an example of an ink ribbon.
FIG. 2 is a cross-sectional view showing an example of a die head in the coating apparatus of the present invention.
FIG. 3 is an explanatory view showing a coating state of two liquids by the die head shown in FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Upstream lip 2 Downstream lip 3 Center lip 4 1st slot 5 2nd slot 6 Base material A, B Coating liquid R Ink ribbon

Claims (2)

By switching, at least two or more slots each discharging different coating liquids from the tip end portion are provided, and the first lip on the upstream side among the plurality of lips forming each slot is projected, and the remaining lips A coating apparatus comprising an extrusion type die head having a front end surface that is flush with a front end side of a flow path in each slot. A coating method using the coating apparatus according to claim 1, wherein each of the respective slots is switched by switching a slot for discharging the coating liquid from the tip portion in a state where the tip portion of the die head is in contact with the traveling substrate . A coating method characterized by intermittently discharging different coating liquids from a slot and repeatedly coating different coating liquids on a substrate in a pattern.

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