JPH0550004A - Coating method for coating liquid and coating device therefor - Google Patents

Abstract

PURPOSE:To prevent unequal thicknesses and coating lines by coating the surface of a base film with the coating liquid discharged from a coating liquid outflow slit via a coating liquid pool formed with its sectional area decreasing continuously toward its transverse direction from a coating liquid injection port provided in an extrusion type coating head. CONSTITUTION:The extrusion type coating head 1 is internally provided with the coating liquid pool 3 communicating with the coating liquid injection port 2 and is disposed with a coating head downstream end 4 and a coating head 1 upstream end 5. The coating liquid outflow slit 6 is formed between these ends. The coating liquid 7 is supplied from the coating liquid injection port 2 to the coating liquid pool 3 and is discharged from the coating liquid outflow slit 6 to the continuously traveling base film 8 to form a coating film 9. The coating liquid pool 3 is sectionally circular and is reduced in the sectional area to a circular conical shape in its coating width direction. Consequently, the coating liquid 7 is discharged at a specified outflow velocity distribution at the entire width of the coating liquid outflow slit 6 and the coating film having a uniform coating thickness distribution without having the unequal thicknesses in the transverse direction is formed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coating liquid coating method using an extrusion type coating head and an apparatus therefor, and more specifically, it uses an extrusion type coating head to coat a coating liquid over a wide range of coating conditions. The present invention relates to a method and apparatus for uniformly coating without causing unevenness in thickness and coating stripes.

[0002]

2. Description of the Related Art Generally, various aqueous solutions or resin solutions, or various dispersions prepared by mixing and dispersing various powders in a dispersion medium such as water or an organic solvent are applied on a continuously moving base film. As a method, an indirect coating method such as a gravure method, a reverse roll method, and a kiss coat method has been widely put into practical use. However, in these indirect coating methods, since the coating solution is exposed to the air, there are drawbacks as the coating method of the coating solution in which the property changes easily.
In particular, this tendency is remarkable in a magnetic coating liquid prepared by mixing and dispersing magnetic powder with a binder resin,
The deterioration of coating film quality is liable to occur due to property changes caused by waterfall in the air. Therefore, in recent years, instead of these indirect coating methods, a direct coating method such as an extrusion method has been adopted (Japanese Patent Laid-Open No. 57-8477).
1, JP-A-58-104666, JP-A-60-23.
No. 8179), according to this extrusion method,
Since the coating liquid is completely sealed until it is applied on the base film, it is possible to suppress the change in the properties of the coating liquid as much as possible, and it is easy to deal with the speeding up of the coating process.

[0003]

However, in this conventional extrusion method, the amount and viscosity range of the coating liquid that can be applied are narrow, and the coating liquid flowing in the coating liquid outlet slit is at the end in the coating width direction. The pressure loss increases as it becomes closer to the portion, and it becomes difficult to flow due to the increase in the pressure loss. Especially, in the wall surface portion, the friction loss becomes maximum and there is almost no flow of the coating liquid, and the state becomes stagnant. On the other hand, in the central portion in the coating width direction, the pressure loss becomes minimum and the coating liquid easily flows. Therefore, there is a drawback that the shape distribution in the width direction of the coating film is thicker in the central portion and thinner in the end portions, and in particular, uneven coating amount in the width direction easily occurs, and a uniform and high-quality coating film is obtained. Difficult to do. Further, when a sufficient amount of the coating liquid is not supplied to the extrusion type coating head, the flow of the coating liquid at the end of the coating liquid outflow slit is further deteriorated, and coating in the entire coating width direction becomes impossible.

[0004]

SUMMARY OF THE INVENTION The present invention has been made as a result of various studies in view of the above-mentioned current situation, and a coating solution on a base film is continuously moved by using an extrusion type coating head. When applying to the
The coating liquid is applied onto the base film from the coating liquid outflow slit through the coating liquid reservoir whose cross-sectional area is continuously reduced in the width direction from the coating liquid injection port provided in the John type coating head. By this, the coating liquid discharged from the coating liquid outflow slit and applied on the base film is uniformly discharged in the entire coating width direction, without causing thickness unevenness or coating stripes in a wide range of coating conditions, This is to enable uniform coating, and in particular, to obtain a high-quality coating having a uniform shape distribution in the width direction of the coating.

Hereinafter, description will be given with reference to the drawings showing each example of a coating liquid coating apparatus used in the present invention. FIG. 1 shows an example of an extrusion-type coating head used in the present invention. The extrusion-type coating head 1 has a coating liquid reservoir 3 communicating with a coating liquid injection port 2 inside and The coating head downstream end 4 and the coating head upstream end 5 are arranged in the
The coating liquid outflow slit 6 is formed between the coating liquid and the upstream end 5 of the coating head.

A coating liquid 7 is supplied from a coating liquid inlet 2 to a coating liquid reservoir 3 and is discharged from a coating liquid outflow slit 6 onto a continuously running base film 8 to be coated, and a coating film 9 is formed. Is formed.

Here, the coating liquid reservoir 3 is shown in FIGS.
As shown in FIG. 5, the cross-sectional shape is circular, and the cross-sectional area is formed in a conical shape in the coating width direction with respect to the center point thereof.

Therefore, when the coating liquid 7 is discharged from the coating liquid outflow slit 6 through the coating liquid reservoir 3, the sectional shape is circular, and the sectional area is conical in the coating width direction with reference to the center point thereof. By the coating liquid reservoir 3 formed to be small, the outflow pressure of the coating liquid 7 in the width direction in the coating liquid outflow slit 6 and the pressure loss in the coating liquid outflow slit 6 are balanced, and the coating liquid outflow is achieved. The coating liquid 7 is discharged with a constant outflow velocity distribution in the entire width direction within the slit 6. Therefore, the shape distribution of the coating film is uniform, and a uniform coating film having no thickness unevenness in the width direction is formed. Even if the coating conditions such as the viscosity of the coating liquid 7, the coating speed, and the coating amount are changed, the uniform coating is performed. Thus, a uniform coating film having no thickness unevenness in the width direction can be formed under a wide range of coating conditions.

The coating liquid inlet 2 for supplying the coating liquid 7 to the coating liquid reservoir 3 may be located at any position within the coating liquid reservoir 3, but considering the flow of the coating liquid 7, It is preferable that the coating liquid pool 3 is located at the center of the pool 3 in the width direction.

The cross-sectional area of the coating liquid reservoir 3 may be continuously reduced from the coating liquid injection port 2 in the width direction, but if the gradient when continuously reducing is 1 degree or less. When the edge in the coating width direction becomes thicker and the gradient becomes 15 degrees or more, the central portion in the coating width direction becomes thicker and uniform coating is impossible. Therefore, the gradient is 2 to 10 degrees with a gradient deviation of 1 to 45%. More preferably, it is continuously reduced.

FIGS. 3 and 4 show another example of the extrusion type coating head used in the present invention. The extrusion type coating head 1a is
The shape of the coating liquid reservoir 3a communicating with the coating liquid inlet 2a is
1 and 2 except that the cross-sectional shape is semi-circular, and the diameter of the semi-circle is continuously reduced from the center in the width direction to continuously reduce the cross-sectional area in the coating width direction. It is configured in the same manner as the extrusion type coating head 1.

FIGS. 5 and 6 show other examples of the extrusion type coating head used in the present invention. The extrusion type coating head 1b communicates with the coating liquid injection port 2b. Coating liquid reservoir 3b
The cross-sectional shape is rectangular and the coating head upstream end 5b
The construction is the same as that of the extrusion-type coating head 1 shown in FIGS. 1 and 2, except that the side is inclined upward from the center in the width direction so that the cross-sectional area continuously decreases in the coating width direction. Has been done.

Further, FIGS. 7 to 9 show other examples of the extrusion type coating head used in the present invention. The extrusion type coating head 1c communicates with the coating liquid injection port 2c. Application liquid pool 3
c has a rectangular cross-sectional shape, and the coating head upstream end 5
Extrusion type shown in FIG. 1 and FIG. 2 except that the c side is inclined upward from the center in the width direction and at the same time it is widened toward both tip ends so that the cross-sectional area continuously decreases in the coating width direction. It is configured in the same manner as the coating head 1.

In the case of the extrusion type coating heads 1a, 1b and 1c shown in FIGS. 3 to 9, however, the cross-sectional areas of the coating liquid reservoirs 3a, 3b and 3c are continuous in the coating width direction. Therefore, as in the extrusion-type coating head 1 shown in FIGS. 1 and 2, the outflow velocity distribution of the coating liquid 7 in the width direction in each of the coating liquid outflow slits 6a, 6b, 6c. Can be made constant, the shape distribution of the coating film can be made uniform, and a uniform coating film having no thickness unevenness in the width direction can be formed.
Further, even if the coating conditions such as the viscosity, the coating speed and the coating amount of the coating liquid 7 are changed, uniform coating can be carried out, and a uniform coating film having no thickness unevenness in the width direction is formed under a wide range of coating conditions. It

The cross-sectional shape of the coating liquid reservoir is not limited to the above examples, but may be various shapes, for example, fan-shaped or polygonal, and the cross-sectional area in the coating width direction is continuously small. It may be.

[0016]

EXAMPLES Next, examples of the present invention will be described. Example 1 Co-deposited γ-Fe ₂ O ₃ (long axis diameter 0.4 μm, short axis diameter 0.05 500 parts by weight μm, coercive force 600 oersted) Nitrocellulose 50 〃 Pandex T-5250 (Dainippon Ink and Chemicals Incorporated) Made, 30〃 Polyurethane resin, Coronet L (Nippon Polyurethane Industry Co., Ltd., trifunctional low 20〃 Molecular weight isocyanate compound) Mogal L (Cabot Co., carbon black) 10〃 Myristic acid 3〃 Butyl stearate 2 〃 Methyl isobutyl ketone 720 〃 Toluene 720 〃 This composition was mixed and dispersed with a ball mill for 72 hours to prepare magnetic paints of Samples 1 to 9 having respective viscosities shown in Table 1 below. As shown in FIGS. 1 and 2, this magnetic paint has a circular cross-sectional shape and a gradient cross-sectional area of 10 in the coating width direction.
On the polyester film 8, an extrusion-type coating head 1 provided with a coating liquid reservoir 3 having a structure in which the degree and the gradient deviation are 30% is continuously reduced is discharged at each coating liquid injection amount shown in Table 1 below. And then dried to form the magnetic layers 9 of Samples 1 to 9.

[0017]

Example 2 In the same manner as in Example 1, Samples 1 to 1 having the respective viscosities shown in Table 1 were prepared.
9 magnetic paints were prepared. Next, in place of the extrusion-type coating head 1 used in Example 1, as shown in FIGS. 3 and 4, the cross-sectional shape was semicircular, the cross-sectional area was 10 degrees in the coating width direction, and the gradient deviation was 30%. These magnetic paints were applied to each of the coating liquids shown in Table 1 in the same manner as in Example 1 except that the extrusion-type coating head 1a provided with the coating liquid reservoir 3a having a continuously smaller structure was used. And then dried to form the magnetic layers of Samples 1 to 9.

Example 3 In the same manner as in Example 1, Samples 1 to 1 having various viscosities shown in Table 1 were prepared.
9 magnetic paints were prepared. Then, instead of the extrusion-type coating head 1 used in Example 1, as shown in FIGS. 5 and 6, the cross-sectional shape is rectangular and the cross-sectional area in the coating width direction is continuous at a gradient of 10 degrees and a gradient deviation of 30%. These magnetic paints were prepared in the same manner as in Example 1 except that the extrusion type coating head 1b provided with the coating liquid reservoir 3b having a structure that becomes smaller in size was used. After coating and drying, the magnetic layers of Samples 1 to 9 were formed.

Example 4 Samples 1 to 1 of each viscosity shown in Table 1 were prepared in the same manner as in Example 1.
9 magnetic paints were prepared. Then, instead of the extrusion-type coating head 1 used in Example 1, as shown in FIGS. 7 to 9, the cross-sectional shape is rectangular and the cross-sectional area in the coating width direction is 5 degrees and the gradient deviation is 30%. These magnetic paints were prepared in the same manner as in Example 1 except that the extrusion-type coating head 1c provided with the coating liquid reservoir 3c having an extremely small structure was used. After coating and drying, the magnetic layers of Samples 1 to 9 were formed.

Example 5 Samples 1 to 1 of each viscosity shown in Table 1 were prepared in the same manner as in Example 1.
9 magnetic paints were prepared. Then, in place of the extrusion-type coating head 1 used in Example 1, as shown in FIGS. 7 to 9, the cross-sectional shape was rectangular and the cross-sectional area was 5 degrees continuously in the coating width direction and the gradient deviation was 5%. These magnetic paints were prepared in the same manner as in Example 1 except that the extrusion-type coating head 1c provided with the coating liquid reservoir 3c having an extremely small structure was used. After coating and drying, the magnetic layers of Samples 1 to 9 were formed.

Comparative Example 1 Samples 1 to 1 of each viscosity shown in Table 1 were prepared in the same manner as in Example 1.
9 magnetic paints were prepared. Then, instead of the extrusion-type coating head 1 used in Example 1, a columnar coating liquid reservoir 3d having a circular cross-sectional shape and the same cross-sectional area in the coating width direction as shown in FIGS. Samples 1 to 9 were coated with these magnetic coating materials in the same amounts as the coating liquid injection amounts shown in Table 1 above in the same manner as in Example 1 except that the provided extrusion type coating head 1d was used. The magnetic layer of was formed. In the case of Samples 1 and 6, the magnetic coating did not flow out in the coating width direction and the formation of the magnetic layer was incomplete.

Comparative Example 2 Samples 1 to 1 of each viscosity shown in Table 1 were prepared in the same manner as in Example 1.
9 magnetic paints were prepared. Next, instead of the extrusion-type coating head 1 used in Example 1, as shown in FIGS. 12 and 13, a semi-cylindrical coating liquid reservoir having a semicircular cross-sectional shape and the same cross-sectional area in the coating width direction. Sample 1 was coated with these magnetic coating materials at the coating liquid injection amounts shown in Table 1 above in the same manner as in Example 1 except that the extrusion type coating head 1e equipped with 3e was used. 9 magnetic layers were formed. In the case of Sample 6, the magnetic coating did not flow out in the coating width direction and the formation of the magnetic layer was incomplete.

Comparative Example 3 Samples 1 to 1 of each viscosity shown in Table 1 were prepared in the same manner as in Example 1.
9 magnetic paints were prepared. Then, instead of the extrusion-type coating head 1 used in Example 1, as shown in FIGS. 14 and 15, a prismatic coating liquid reservoir 3f having a rectangular cross-sectional shape and the same cross-sectional area in the coating width direction was used. Samples 1 to 9 were coated with these magnetic coating materials in the same amounts as the coating liquid injection amounts shown in Table 1 above in the same manner as in Example 1 except that the provided extrusion type coating head 1f was used. The magnetic layer of was formed. In the case of Samples 1, 6 and 7, the magnetic coating did not flow out in the coating width direction and the formation of the magnetic layer was incomplete.

In each of the Examples and Comparative Examples, the coating thickness unevenness in the coating width direction of the magnetic layer obtained by coating the magnetic coating material was measured by a fluorescent X-ray micrometer film thickness meter (manufactured by Seiko Electronics Co., Ltd .; S
FT-156, collimator spot diameter 0.5 mm) was used and the deviation from the average film thickness was shown in percentage. Table 2 below
Is the result.

[0026]

[0027]

As is clear from Table 2 above, the magnetic layer obtained by the coating apparatus and coating method of the present invention (Example 1)
.About.5) have less unevenness in coating thickness than the magnetic layers (Comparative Examples 1 to 3) obtained by the conventional coating method,
From this, according to the coating apparatus and the coating method of the present invention, even if the coating conditions are changed over a wide range by using coating materials having different viscosities, good coating can be performed without causing coating thickness unevenness, It can be seen that a high-quality coating film can be obtained, which can greatly contribute to the improvement of productivity.

[0028]

[Brief description of drawings]

FIG. 1 is an extruder showing an example of a coating apparatus of the present invention.
It is a schematic sectional drawing of a John type coating head.

2 is a cross-sectional view of the extrusion-type coating head shown in FIG. 1 taken along the line AA.

FIG. 3 is a schematic sectional view of an extrusion-type coating head showing another example of the coating apparatus of the present invention.

FIG. 4 is a cross-sectional view taken along line BB of the extrusion-type coating head shown in FIG.

FIG. 5 is a schematic sectional view of an extrusion-type coating head showing another example of the coating apparatus of the present invention.

6 is a cross-sectional view taken along line BB of the extrusion-type coating head shown in FIG.

FIG. 7 is a schematic sectional view of an extrusion-type coating head showing another example of the coating apparatus of the present invention.

8 is a cross-sectional view taken along line AA of the extrusion-type coating head shown in FIG.

9 is a cross-sectional view taken along line BB of the extrusion-type coating head shown in FIG.

FIG. 10 is a schematic sectional view showing an example of a conventional extrusion-type coating head.

11 is a sectional view taken along line AA of the extrusion-type coating head shown in FIG.

FIG. 12 is a schematic sectional view showing another example of a conventional extrusion-type coating head.

13 is a sectional view taken along line BB of the extrusion-type coating head shown in FIG.

FIG. 14 is a schematic sectional view showing another example of a conventional extrusion-type coating head.

15 is a sectional view taken along line BB of the extrusion type coating head shown in FIG.

[Explanation of symbols]

1,1a, 1b, 1c Extrusion type coating head 2,2a, 2b, 2c Coating liquid inlet 3,3a, 3b, 3c Coating liquid reservoir 4,4a, 4b, 4c Coating head downstream end 5,5a, 5b , 5c Coating head upstream end 6,6a, 6b, 6c Coating liquid outflow slit 7 Coating liquid (magnetic paint) 8 Base film (polyester film)

Claims (6)

[Claims] 1. When applying a coating solution onto a base film that continuously moves using an extrusion type coating head, the coating solution is introduced in a width direction from a coating solution injection port provided in the extrusion type coating head. A coating method for coating a coating liquid, characterized in that the coating liquid is coated on a base film through a coating liquid discharge slit through a coating liquid reservoir whose cross-sectional area is continuously reduced. 2. The coating liquid pool according to claim 1, wherein the coating liquid pool is a coating liquid pool whose cross-sectional area is continuously reduced with a gradient deviation of 1 to 45% from the coating liquid injection port in the width direction. Method 3. The coating liquid injection port of the extrusion-type coating head is arranged in the central portion in the width direction of the coating liquid reservoir, and the coating liquid is injected into the coating liquid reservoir from this coating liquid inlet. Application method of the application liquid according to 2 4. A coating apparatus for coating a coating solution on a base film which continuously moves by using an extrusion type coating head, wherein the width of the extrusion type coating head is wider than the coating solution injection port. A coating liquid coating device for coating the coating liquid on the base film from the coating liquid outflow slit through the coating liquid reservoir, the coating liquid reservoir having a continuously reduced cross-sectional area. 5. The coating liquid reservoir according to claim 4, wherein the coating liquid reservoir is a coating liquid reservoir whose cross-sectional area is continuously reduced with a gradient deviation of 1 to 45% from the coating liquid inlet in the width direction. apparatus 6. The coating liquid coating apparatus according to claim 4 or 5, wherein the coating liquid injection port of the extrusion-type coating head is arranged at the central portion in the width direction of the coating liquid reservoir.