JP2563732B2 - nozzle - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a nozzle for manufacturing a magnetic recording medium used as a magnetic tape or a floppy disk, and more particularly to improvement of the nozzle.

[0002]

2. Description of the Related Art There is a nozzle for manufacturing a magnetic recording medium, in which a magnetic paint or the like is extruded from the nozzle and the paint is directly applied on a support such as a film to form a magnetic layer or the like. Such a conventional nozzle is disclosed in, for example, Japanese Patent Laid-Open No. 3-32768 as shown in FIG. The feature of the nozzle is that the paint 7 is continuously extruded from a slit 4 formed in a space between the upstream lip 2 and the downstream lip 1 and having a parallel gap to apply the paint onto the support 8. , The non-coated side of the support 8 does not support anything,
The pressure is applied from the coating material 7 pushed out from the slits 4, while the clearance between the downstream lip 1 having a curved lip surface and the support 8 is maintained.

[0003]

The coating thickness of the magnetic recording medium is generally in the range of 2 to 4 .mu.m. However, for high density recording, the thickness of the magnetic layer is reduced in order to reduce the thickness loss. The thinner one is preferable. However, 0.1 with the conventional nozzle
When a magnetic recording medium having a thin film thickness of up to 0.3 μm is to be produced, film thickness unevenness occurs in the coating width direction, which is a fatal defect as a product. As a result of extensive studies on the cause, the present inventor has found that the reason is as follows.

The coating film thickness is determined by the running speed of the support and the amount of paint extruded from the slit 4 of the nozzle. The coating speed must be the same as when the coating film thickness is 2 to 4 μm due to the productivity and the like. Therefore, the coating film thickness is 0.1 to 0.3 μm.
In this case, the amount of paint extruded is about 1/7 to 1/40, which is much smaller than the amount of paint extruded when the film thickness is 2 to 4 μm. When the amount of paint extruded is small, the amount of paint extruded from the slit 4 varies in the application width direction due to the influence of the variation in pressure loss in the application width direction in the slit 4, resulting in the film thickness in the application width direction. The unevenness occurred. Of course, when the film thickness is as thick as 2 to 4 μm, such film thickness unevenness in the width direction does not occur because the amount of the coating material flowing in the slit 4 is large.

Even if an attempt was made to solve the above-mentioned problems with a conventional nozzle, it was impossible. That is, in the conventional nozzle,
As shown in (FIG. 3), the slit gaps from the slit inlet to the slit outlet are parallel. In order to eliminate variations in pressure loss in the slit 4 in the width direction, the slit 4
When the amount of the paint extruded from the slit 4 is small, the paint is extruded in some areas in the application width direction and in some areas not extruded, making it impossible to uniformly apply the ink in the width direction. Further, in order to reduce the pressure loss in the slit 4, if the slit length is shortened to about 15 mm with a conventional nozzle, for example, it will be affected by the pressure distribution in the coating width direction in the manifold 3 which is a liquid reservoir of the coating material. Also results in uneven film thickness in the width direction.

The object of the present invention is to obtain a coating film thickness of 0.1 to 0.3.
It is an object of the present invention to provide a nozzle capable of uniformly coating a thin magnetic layer of μm in the coating width direction.

[0007]

In order to solve the above-mentioned problems, the nozzle of the present invention has a structure in which a coating material is continuously extruded from a slit to the above-mentioned support without supporting the side opposite to the coated surface of the support which is continuously running. A nozzle for applying a slit parallel portion in which the slit gap is parallel, and a slit provided with a taper in which the slit gap widens as it approaches the slit inlet from the end of the slit parallel portion on the side opposite to the slit outlet. A nozzle having a taper portion, the slit length of the slit parallel portion in the paint extrusion direction is L2,
When the slit length in the paint extrusion direction of the slit taper portion is L1, the range is 5 mm ≦ L1 1 mm ≦ L2 ≦ 15 mm, and the slit gap in the slit parallel portion is 0.0.
It is in the range of 5 mm to 0.5 mm, the maximum gap of the slit taper portion is d1, and the gap of the slit parallel portion is d2.
Then, 0.01 ≦ (d1−d2) /L1≦0.5 is satisfied.

[0008]

According to the structure of the present invention, the slit length in the slit parallel portion in the paint pushing direction is in the range of 1 to 15 mm. Therefore, the paint is hardly affected by the pressure loss when the paint flows through the slit parallel portion. It can be extruded uniformly in the coating width direction of the slit parallel portion. Further, since the slit length of the slit taper portion in the paint pushing direction is 5 mm or more, when the paint flows through the slit taper portion, the pressure distribution in the coating width direction in the manifold is made uniform in the slit taper portion. . Therefore, at the entrance of the slit parallel portion, the pressure in the coating width direction is already equalized, so that the paint can be extruded uniformly from the slit parallel portion. Further, since the slit gap of the slit taper portion is wider than that of the slit parallel portion, the pressure loss in the slit taper portion is so small that it can be ignored. Therefore, even in a thin film thickness of 0.1 to 0.3 μm It becomes possible to apply a uniform film thickness in the width direction.

[0009]

【Example】

(Embodiment 1) Hereinafter, an embodiment of the present invention will be specifically described with reference to the drawings. (FIG. 1) is a cross-sectional view of a state in which paint is applied by the nozzle in this embodiment. The paint 7 is supplied by the pump 6 to the manifold 3 provided on the nozzle 5.
The paint 7 is supplied into the slit taper portion 10 and flows into the slit taper portion 10. The slit taper portion 10 is configured so that a gap widens in the direction of the manifold 3, and the slit length L1 of the slit taper portion 10 in the paint extrusion direction is 5
mm or more. When the value of L1 is smaller than 5 mm, the pressure distribution in the coating width direction in the manifold 3 cannot be made uniform in the slit taper portion 10,
Thickness unevenness occurs in the coating width direction.

Further, a slit parallel portion 9 is provided continuously with the slit taper portion 10. In the slit parallel portion 10, the slit gaps are parallel, the slit length L2 in the paint extrusion direction is in the range of 1 to 15 mm, and the gap d2 is 0.
The range is 05 to 0.5 mm. If L2 is smaller than 1 mm, the coating flow cannot be made into a laminar flow state in the slit parallel portion 9, and uneven film thickness occurs in the coating width direction. This is because if the flow of the paint extruded from the slit parallel portion outlet 15 is not in the laminar flow state, film thickness unevenness occurs in the coating width direction, but the paint flowing in the slit taper portion 10 is not in the laminar flow state. This is because it is necessary to set L2 to 1 mm or more to make the paint flow laminar in the slit parallel portion. When L2 is larger than 15 mm, the pressure loss in the slit parallel portion 9 becomes large, and the film thickness unevenness occurs in the coating width direction due to the variation of the pressure loss in the coating width direction.

Further, when the slit taper portion 10 is constructed so that the relationship of d1, d2, and L1 satisfies the following equation, it becomes possible to apply uniformly in the application width direction.

0.01 ≦ (d1−d2) /L1≦0.5 If the value of the above equation is smaller than 0.01, the slit gap of the slit taper portion 10 becomes too close to parallel, and the slit taper portion 10 The pressure loss in the inside becomes so large that it cannot be ignored, and unevenness of the film thickness occurs due to the variation of the pressure loss in the coating width direction.

Further, if the value of the above equation is larger than 0.5, the taper amount becomes too steep, and the paint flows into the slit parallel portion 9 while the flow of the paint is in a turbulent state. The film thickness becomes uneven in the width direction.

As the nozzle of the present invention, L1 is 5 mm, d2
Is fixed at 0.2 mm, L2 is 1 mm and 15 mm, (d
1-d2) / L1 is 0.01 and 0.5 nozzles of each combination are prepared, and the coating material shown in (Table 1) is applied onto a support made of polyethylene terephthalate at a coating speed of 200 m / m.
The coating was applied so that the coating thickness was 0.3 μm in in, and the unevenness of the thickness in the width direction was measured. The results (Table 2)
Are shown together.

[0015]

[Table 1]

[0016]

[Table 2]

According to the nozzle of the present invention, it can be seen that the effect of uniformly coating the film thickness in the coating width direction is remarkable.

(Embodiment 2) In the present invention, (FIG. 2)
As shown in FIG.
The second gap that is the same gap as the gap d1 and the slit gaps are parallel to each other
Even if the slit parallel portion 16 is provided, the same effect as that of (Example 1) was obtained.

(Comparative Example) With a nozzle according to Japanese Patent Laid-Open No. 3-32768, the coating material shown in (Table 1) was coated on a support made of polyethylene terephthalate at a coating speed of 200 m / m.
(Table 2) collectively shows the results of measuring the film thickness unevenness in the width direction by applying a film having a coating film thickness of 0.3 μm in in.

[0020]

As described above, according to the present invention, the film thickness of 0.
A thin magnetic recording medium having a thickness of 1 to 0.3 μm can be uniformly applied in the application width direction, and product performance and quality can be significantly improved.

[Brief description of drawings]

FIG. 1 is a side sectional view of a nozzle according to a first embodiment of the present invention.

FIG. 2 is a side sectional view of a nozzle according to a second embodiment of the present invention.

FIG. 3 is a side sectional view of a conventional nozzle.

[Explanation of symbols]

 1 downstream lip 2 upstream lip 3 manifold 4 slit 5 nozzle 6 pump 7 paint 8 support 9 slit parallel part 10 slit taper part 11 slit inlet 12 slit exit 13 slit taper part inlet 14 slit parallel part inlet 15 slit parallel part outlet 16 Second slit parallel part

Claims (1)

(57) [Claims] 1. A nozzle for continuously extruding a coating material from a slit to apply the coating material to the support without supporting the side opposite to the coating surface of the support that is continuously running, wherein the slit parallel portion has a parallel gap between the slits. And a slit taper portion provided with a taper in which the gap of the slit expands from the end of the slit parallel portion on the side opposite to the slit outlet toward the slit inlet, and the paint is extruded from the slit parallel portion. Where L2 is the slit length in the direction and L1 is the slit length in the paint extrusion direction of the slit taper portion, the range is 5 mm ≦ L1 1 mm ≦ L2 ≦ 15 mm, and the slit gap in the slit parallel portion is 0.0.
It is in the range of 5 mm to 0.5 mm, the maximum gap of the slit taper portion is d1, and the gap of the slit parallel portion is d2.
The nozzle is characterized by satisfying the following condition: 0.01 ≦ (d1−d2) /L1≦0.5.