JP3385431B2 - Application method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION This invention relates to a coating method of applying the coating solution to a running support, more particularly a coating method of applying a magnetic dispersion to a flexible web.

[0002]

2. Description of the Related Art In recent years, due to demands for high speed thin film coating,
Extrusion type coating devices have been adopted in various fields (JP-A-58-104666, JP-A-60-238179, JP-A-60-238179).
Inventions described in JP-A-62-117666 and JP-A-2-265672). These extrusion type coating devices are provided with an upstream lip and a downstream lip at the tip (hereinafter referred to as a die head), and a slot portion capable of extruding a coating liquid (for example, a magnetic dispersion liquid) is formed between these lips. Is
The above-mentioned coating liquid is applied to a support (for example, a web) which runs opposite to the upstream lip and the downstream lip.

As shown in FIGS. 9 (A) and 10 (A), such extrusion type coating apparatuses 1 and 11 are used.
Of the upstream lips 2 and 12 and the downstream lips 3 and 13, the downstream lips 3 and 13 are formed such that the tip surface (coating work surface) thereof is a flat surface or a single arc surface. One of the reasons for this is the ease of processing. That is, the downstream lips 3 and 13 are made of a high hardness material such as cemented carbide, and still require high processing precision (submicron unit). Therefore, the application work surface of the downstream lips 3 and 13 is limited to a simple shape such as a flat surface or a single arc surface. In addition, reference numerals 4 and 14 in FIGS. 9 and 10 denote slot portions.

[0004]

However, the coating operation surfaces of the downstream lips 3 and 13 are extremely closely related to the coating operation conditions such as the coating speed, the coating film thickness, and the coating type. The shape must be determined in consideration of the conditions.

For example, in the coating device 1 in which the coating work surface of the downstream lip 3 is flat, as shown in FIGS. 9A and 9B, the coating work surface of the downstream lip 3 is between the web 5 and the coating work surface. The liquid pressure of the coating liquid 6 that is extruded and acts on the web 5 is at a position corresponding to the upstream end (point b) of the coating work surface of the downstream lip 3 and a position immediately before the downstream end (point c). At, the pressure concentrates and increases. It is necessary to set the liquid pressure of the coating liquid 6 to a predetermined value or more at the position corresponding to the point b, from the viewpoint of preventing the occurrence of coating film defects due to air inclusion in the coating film. However, at other positions, it is necessary to set the hydraulic pressure low to reduce the load acting on the web 5. Therefore, in the case of this coating apparatus 1, the range of coating operation conditions that can realize favorable coating is extremely narrow.

Further, in the coating device 11 in which the coating work surface of the downstream lip 13 is a single arc surface, FIGS. 10 (A) and 10 (B) are used.
As shown in, the hydraulic pressure of the coating liquid 6 extruded between the coating work surface of the downstream lip 13 and the web 5 and acting on the web 5 is not concentrated at the position corresponding to immediately before the point c. Unnecessary pressure is generated between bc.
For this reason, if the coating operation conditions are slightly changed, as shown in FIG.
As shown by the broken line in (B), the pressure of the coating liquid fluctuates, and the load acting on the web 5 increases. Therefore, even in the case of the coating apparatus 11, the range of coating operation conditions that can realize good coating is narrowed.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a coating method capable of expanding the range of coating operation conditions capable of realizing favorable coating.

[0008]

The above problems of the present invention are as follows.
It was achieved by the following means. (1) An upstream lip and a downstream lip are provided, and a slot portion capable of extruding the coating liquid is formed between these lips.
In the coating method of applying the coating liquid to a support that runs opposite to the upstream lip and the downstream lip by using the coating device, the coating of the downstream lip is made to face the support. The coating work surface in contact with the liquid is formed to be curved toward the support, the tension of the support is T, and the pressure at which the coating liquid acts on the support at each of the upstream end and the downstream end of the coating work surface. Is P ₁ and P ₂ , the curvature K of the curved coating work surface is set to P ₂ / T ≦ K ≦ P ₁ / T.

(2) An upstream lip and at least two downstream lips are provided, and the coating liquid can be extruded between the upstream lip and one of the downstream lips and between the downstream lips. Coating device with slot
Method for applying the coating liquid to a support that runs opposite the upstream lip and the downstream lip using
In the method , a coating work surface facing the support and in contact with the coating liquid is formed on each of the downstream lips, and at least one of the coating work surfaces is convexly curved toward the support to support the support. When the tension of the body is T, and the pressures of the coating liquid acting on the support at the upstream end and the downstream end of the curved coating work surface of the downstream lip are P ₁ and P ₂ , respectively, the curve is curved. Curvature K of coating work surface
Is set to P ₂ / T ≦ K ≦ P ₁ / T.

[0010]

Therefore, according to the coating method of the invention described in (1) or (2) , the coating work surface of the downstream lip is convexly curved toward the support, and the tension of the support is T, and the coating is curved. When the pressures at which the coating liquid acts on the support at the upstream end and the downstream end of the coating work surface are P ₁ and P ₂ , the curvature K of the curved coating work surface is P ₂ / T ≦ K ≦ P ₁ Since / T is set in the range, the liquid pressure of the coating liquid extruded between the curved coating work surface of the downstream lip and the support becomes maximum at the upstream end of this coating work surface, It gradually decreases toward the minimum and becomes the smallest at the downstream end. As a result, even if the coating operation conditions such as the coating speed and the viscosity of the coating liquid are different and the liquid pressure of the coating liquid between the curved coating work surface and the support is changed, the change in the liquid pressure is within the allowable range. It fits. Therefore, it is possible to expand the range of coating operation conditions that can realize good coating.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 can be used in the coating method according to the present invention.
It is a cross-sectional view of a die head illustrating a first coating apparatus embodiment that. FIG. 2 is a cross-sectional view showing a part of FIG. 1 in an enlarged manner. Figure 3
3 is a graph showing the liquid pressure of the coating liquid extruded between the lip and the web of the die head of FIG. 1 in relation to the coating work surface length.

A coating device 20 shown in FIG. 1 is an extrusion type coating device, and is a device for coating a coating liquid on a continuously running support. Here, the support is a flexible sheet or web of plastic, paper, cloth or metal. Further, the coating liquid is a magnetic dispersion liquid, a photosensitive liquid, a heat-sensitive dispersion liquid or an adhesive liquid, which is used to produce a magnetic recording medium, a photographic film, a thermal paper or an adhesive tape, respectively. In this coating apparatus example, a case where a web 21 is used as a support and a magnetic dispersion liquid 22 is used as a coating liquid to manufacture a magnetic recording medium is shown.

The coating device 20 has a die head 23, and an upstream lip 24 and a downstream lip 25 are formed on the die head 23. A slot portion 26 is formed between the upstream lip 24 and the downstream lip 25, and the slot portion 26 communicates with the liquid buffer portion 27. The upstream lip 24 and the downstream lip 25 are set to have substantially the same width as the width of the web 21. Further, the slot portion 26 and the liquid buffer portion 27 are composed of the upstream lip 24 and the downstream lip 25.
Is formed so as to extend in the full width direction.

The liquid buffer portion 27 is connected to a liquid supply system 28, and the magnetic dispersion liquid 22 from the liquid supply system 28 is distributed so that the coating amount becomes constant in the coating width direction and is supplied to the slot portion 26. . Here, the web 21 is guided by a guide roller (not shown) or the like, and the upstream lip 2
4 and the downstream lip 25, and the vehicle travels without being supported by the back surface. The magnetic dispersion liquid 22 is continuously extruded and applied to the running web 21 from the slot portion 26 of the coating device 20, and a uniform coating film 31 is formed in the width direction of the web 21.

The surface of the tip of the downstream lip 25 facing the web 21 and in contact with the magnetic dispersion liquid 22 is a coating work surface 29 that contributes to coating. The coating work surface 29 is convexly curved toward the web 21 and has _two curvatures K ₁ and K ₂ . That is, the coating work surface 29 is formed into a curved surface having a curvature K _{1 in} the section from the upstream end (opening end of the slot portion 26) B of the coating work surface 29 to the intermediate point D along the traveling direction of the web 21. . Further, the coating work surface 29 is formed into a curved surface having a curvature K _{2 in} the section from the intermediate point D to the downstream end C of the coating work surface. Furthermore, these curvatures K ₁ and K ₂ are
1 is T, and the magnetic dispersion liquid 22 is applied to the web 21 at the upstream end B and the downstream end C of the coating work surface 29.
If the pressure acting on is P ₁ and P ₂ , Is set to.

Therefore, the coating work surface 2 of the downstream lip 25
The liquid pressure of the magnetic dispersion liquid 22 extruded between the web 9 and the web 21 and acting on the web 21 is as shown by the solid line in FIG.
Upstream end B of coating work surface 29 (open end of slot 26)
At the position corresponding to the maximum, gradually decreases toward the downstream, and becomes minimum at the position corresponding to the downstream end C of the coating work surface 29.

As described above, the hydraulic pressure of the magnetic dispersion 22 extruded between the coating work surface 29 of the downstream lip 25 and the web 21 and acting on the web 21 is at the upstream end B of the coating work surface 29. It becomes maximum at the corresponding position, gradually decreases toward the downstream side, and becomes minimum at the corresponding position of the downstream end C of the coating work surface 29. Therefore, even if the coating operation conditions such as the coating speed, the coating film pressure, and the coating type are changed, the change in the hydraulic pressure of the coating liquid 22 between the coating work surface 29 of the downstream lip 25 and the web 21 is: Within the small range L indicated by the broken line in FIG. 3, the hydraulic pressure does not exceed a predetermined value and the load acting on the web 21 is not increased. As a result, it is possible to expand the range of coating operation conditions that can realize good coating.

[0018] In the above-described first coating apparatus example has been described the case where the coating work surface 29 is formed by combining two curved surfaces of different curvatures K ₁ and K _2, these curvatures K ₁ and K ₂
The coating work surface 29 may be formed by a single curvature having the same value.

FIG. 4 can be used in the coating method according to the present invention.
It is sectional drawing which shows some die heads in the example of the 2nd coating device which can be . In this second application device example, the first application device
The same parts as location example will be omitted by retaining the same reference numerals.

The coating work surface 33 of the downstream lip 25 in this coating device example 32 is a curved surface having a curvature K (constant value) in a section BD in the traveling direction of the web 21,
It is formed in a plane (curvature is 0) between the sections DC. The curvature K in this case is such that the tension of the web is T and the coating work surface 3
When the pressures at which the magnetic dispersion liquid 22 acts on the web 21 at the upstream end B and the downstream end C of _{No. 3} are P ₁ and P ₂ , respectively, P ₂ / T ≦ K ≦ P ₁ / T is set.

Therefore, also in the coating device 32, as in the case of the first coating device example 20, the downstream lip 2 is used.
5, the liquid pressure of the magnetic dispersion liquid 22 extruded between the coating work surface 33 and the web 21 and acting on the web 21 exhibits a curve similar to that in FIG. 3, and coating operation conditions that enable good coating to be realized. The range of can be expanded.

FIG. 5 can be used in the coating method according to the present invention.
It is sectional drawing which shows some die heads in the example of the 3rd coating device which can be . FIG. 6 is a graph showing the liquid pressure of the coating liquid extruded between the lip and the web of the die head of FIG. 5 in relation to the coating work surface length. In this third coating device example, the same parts as those in the first coating device example are designated by the same reference numerals, and a description thereof will be omitted.

The coating work surface 35 of the downstream lip 25 in the third coating device example 34 is convexly curved toward the web 21 side, and two arbitrary points P and Q on the work surface 35 correspond to the web 21. Let K _P be the curvature at the point P on the upstream side in the traveling direction,
Assuming that the curvature at the point Q on the downstream side is K _Q , K _P ≧ K _Q is set. Further, these curvatures K _P and K _Q are given by assuming that the liquid pressures of the magnetic dispersion liquid 22 at the upstream end B and the downstream end C of the coating work surface 35 are P ₁ and P _{2, respectively,} and the tension of the web 21 is T. , P ₂ / T ≦ K _P ≦ P ₁ / T P ₂ / T ≦ K _Q ≦ P ₁ / T. Further, in the coating work surface 35, the upstream end B on the coating work surface 35, each set curvature _{K B} in each of the downstream end C, the curvature _{K C} is a _{K B = P 1 / T K} C = P 2 / T To be done. Curvatures K _P , K _Q , K _{B of} each point,
K _C is set so as to satisfy the above expression, and its change is continuous.

Therefore, in this third coating apparatus example,
Curvatures K _P and K _Q at arbitrary points on the coating work surface 35 are set to P ₂ / T ≦ K _P ≦ P ₁ / T P ₂ / T ≦ K _Q ≦ P ₁ / T. Upstream end B, downstream end C
Since the curvature K _B and the curvature K _C in each of the above are set to K _B = P ₁ / T K _C = P ₂ / T , the magnetic dispersion that is extruded between the coating work surface 35 and the web 21 and acts on the web 21. As shown in FIG. 6, the liquid pressure of the liquid 22 becomes maximum at a position corresponding to the upstream end B of the coating work surface 35, and gradually decreases toward the downstream,
It becomes the minimum at the position corresponding to the downstream end C of the coating work surface 35. This hydraulic pressure is the first pressure shown in FIG.
It is linear compared to the case of the coating device example. As a result, the liquid pressure of the magnetic dispersion liquid 22 stays within the range indicated by the broken line with respect to changes in the coating operation conditions, and the range of coating operation conditions that can realize good coating can be further expanded.

FIG. 7 shows a coating method according to the present invention.
It is sectional drawing which shows some die heads in the example of the 4th coating device which can be . Also in this fourth coating apparatus example, each coating
The same parts as those of the cloth device example are denoted by the same reference numerals and the description thereof will be omitted.

In this coating device example 36, the downstream lip is composed of a downstream first lip 37 and a downstream second lip 38. These downstream first lip 37 and downstream second lip
A second slot portion 39 is formed between the lips 38. The downstream first lip 37 constitutes the slot portion 26 in the vicinity of the upper lip 24, and the downstream second lip 38 constitutes the second slot portion 39 together with the downstream first lip 37. In this application device example, the slot portion 26 is hereinafter referred to as the first slot portion 26.

From the first slot portion 26 and the second slot portion 39, the magnetic dispersion liquids 22 of the same kind or different kinds are extruded and applied onto the web 21 to form a multi-layered coating film 40.

A coating work surface 41 of the lower first lip 37.
The coating work surface 42 of the lower second lip 38 and the web 2
It is formed so as to be convexly curved toward the first side. Of these, the coating work surface 4
1 is formed similarly to the coating work surface 35 of the third coating device example. That is, the curvatures K _P and K _{Q at} the arbitrary points P and Q on the coating work surface 41 are K _P ≧ K _Q P ₂ / T ≦ K _P ≦ P ₁ / T P ₂ / T ≦ K _Q ≦ P It is set to ₁ / T. Furthermore, the upstream end B of the coating work surface 41, the curvature _{K B} in each of the downstream end C, the curvature _{K C} is set to _{K B = P 1 / T K} C = P 2 / T.

As for the coating work surface 42, if the curvature of an arbitrary point G on the coating work surface 42 is K _G and the curvature of the downstream point H is K _H , then K _G ≧ K _H is set. It Furthermore, these curvatures K _G and K _H are defined by assuming that the liquid pressures of the magnetic dispersion liquid 22 at the upstream end E and the downstream end F of the coating work surface 42 are P ₃ and P _{4, respectively,} and the tension of the web 21 is T. , P ₄ / T ≦ K _G ≦ P ₃ / T P ₄ / T ≦ K _H ≦ P ₃ / T. Further, the curvature K _E and the curvature K _F at the upstream end E and the downstream end F of the coating work surface 42 are set to K _E = P ₃ / TK _F = P ₄ / T , respectively. Curvatures K _H , K _G , K _{E of} each point,
K _F is set so as to satisfy the above equation, and its change is continuous.

Therefore, also in this fourth coating device example,
The hydraulic pressure of the magnetic dispersion liquid 22 extruded between the coating work surfaces 41 and 42 and the web 21 and acting on the web 21 is as shown in FIG.
As shown in, the first slot portion 26 becomes larger at the corresponding position, and gradually decreases along the flow of the web 22 (the second slot portion 26).
It slightly increases at the position corresponding to the slot portion 39). Therefore, even in this fourth coating device example, the first coating device is also used.
Like the location Examples can expand the range of coating operation conditions that can achieve good coating.

In the fourth coating apparatus example, the coating work surface 41 of the lower first lip 37 and the coating work surface 42 of the lower second lip 38 are both curved, but the coating work surface 41 is described. The coating work surface 42 may have a curved shape and the coating work surface 42 may have a planar shape. Further, the coating work surface 41 may have a planar shape and the coating work surface 42 may have a curved shape.

Further, in the above-mentioned first to fourth coating apparatus examples, the case where the coating work surfaces 29, 33, 35, 41 and 42 are curved convexly on the side of the web 21 has been described. May be

The coating device used in the coating method of the present invention has been described above.
Although it described in detail with reference to the drawings the location example, coating that can be used in the present invention
Specific configuration of the apparatus is not limited to this application example device, it can be used to be present invention there is a change of the design within the range of not departing from the gist of the present invention.

[0034]

As described above, according to the coating method of the present invention , it is possible to expand the range of coating operation conditions that can realize good coating.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a die head showing a first coating apparatus example that can be used in the present invention.

FIG. 2 is a cross-sectional view showing a part of FIG. 1 in an enlarged manner.

3 is a graph showing the liquid pressure of the coating liquid extruded between the lip and the web of the die head of FIG. 1 in relation to the coating work surface length.

FIG. 4 is a sectional view showing a part of a die head in a second coating apparatus example that can be used in the present invention.

FIG. 5 is a cross-sectional view showing a part of a die head in a third coating apparatus example that can be used in the present invention.

6 is a graph showing the liquid pressure of the coating liquid extruded between the lip and the web of the die head of FIG. 5 in relation to the coating work surface length.

FIG. 7 is a cross-sectional view showing a part of a die head in a fourth coating apparatus example that can be used in the present invention.

8 is a graph showing the liquid pressure of the coating liquid pressed between the lip and the web of the die head of FIG. 7 in relation to the coating work surface length.

FIG. 9 (A) shows a conventional coating method.
9B is a cross-sectional view showing an enlarged part of an example of a coating device used in the method , and FIG. 9B shows the liquid pressure of the coating liquid in the coating device of FIG. 9A as the coating work surface length. It is a graph shown by a relation.

FIG. 10 (A) shows a conventional coating.
It is sectional drawing which expands and shows a part of other example of the coating device used for a cloth method , and FIG. 10 (B) shows the hydraulic pressure of the coating liquid in the coating device of FIG. It is a graph shown in relation to length.

[Explanation of symbols]

20 Coating Device 21 Web 22 Magnetic Dispersion Liquid 24 Upstream Lip 25 Downstream Lip 29, 33, 35, 41, 42 Coating Work Surface 36 Coating Device 37 Lower First Lip 38 Lower Second Lip 39 Second Slot K , K ₁ , K ₂ , K _P , K _Q , K _B , K _C , K _G ,
K _H , K _E , K _F curvature

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Chen Ei               2606 Akabane, Kai Town, Haga-gun, Tochigi Kao Corporation               In the company                (56) References Japanese Patent Laid-Open No. 1-2007272 (JP, A)                 JP-A-5-192627 (JP, A)

Claims (5)

(57) [Claims] 1. An upstream lip and a downstream lip are provided,
Using a coating device in which a slot capable of extruding the coating liquid between these lips is used , in a coating method for coating the coating liquid on a support that runs in opposition to the upstream lip and the downstream lip, On the downstream side lip, a coating work surface facing the support and in contact with the coating liquid is curvedly formed on the support side, the tension of the support is T, and the upstream end of the coating work surface is When the coating solution in each of the downstream end to the pressure acting on the support and P _1, P _2, the curvature K of the coating work surface and the curved is more set _{P 2 / T ≦ K ≦ P} 1 / T A coating method characterized by being performed. 2. A slot comprising an upstream lip and at least two downstream lips, wherein the coating liquid can be extruded between the upstream lip and one of the downstream lips and between the downstream lips, respectively. Coating device
In the coating method of applying the coating liquid to a support body that runs in opposition to the upstream lip and the downstream lip, the downstream lip faces the support body. Then a coating work surface in contact with the coating liquid is formed, and at least one of the coating work surfaces is convexly curved toward the support,
Letting T be the tension of the support, and P ₁ and P ₂ be the pressures at which the coating liquid acts on the support at the upstream end and the downstream end of the curved coating work surface of the downstream lip, respectively. coating method curvature K of the curved coated work surface, characterized in that it is more set to _{P 2 / T ≦ K ≦ P} 1 / T. 3. The coating according to claim 1, wherein the curvature K of the curved coating work surface of the downstream lip is a constant value.
Way . 4. The curvature at the point on the upstream side is K _P with respect to any two points on the curved coating work surface of the downstream side lip.
And then, when the curvature at a point downstream and K _Q, The coating method according to claim 1 or 2 of these curvatures K _P, K _Q is set to K _P ≧ K _Q. 5. The curvature of the upstream end of the curved coating work surface of the downstream lip is P ₁ / T, and the curvature of the downstream end is P ₂ / T.
The coating method according to claim 1, 2 or 4 respectively set to T.