JP3187474B2 - Manufacturing method of magnetic recording medium - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a magnetic recording medium.

[0002]

2. Description of the Related Art In a method in which a running web (a support film such as polyester) is stretched between a pair of backup rolls, and a magnetic paint is applied by using an extrusion type coating head in the middle of these rolls, the final coating is performed. It is possible to supply and apply only the amount of paint remaining as a film, it does not require an excessive supply amount as in the conventional gravure method or the roll coating method such as the reverse method, and when speeding up,
There is no problem such as scattering of paint due to centrifugal force due to the rotation of the roll, or scattering due to splitting of paint when transferring the paint to the web, so coating can be speeded up, productivity can be improved, and cost can be reduced. Become.

For speeding up, conventionally, 300 to 400 m
/ Min to 1.5 to 450-600 m / mi by using an extrusion type coating head.
n or higher speed can be achieved.

[0004]

A problem that arises when the speed is increased is the problem of passage of a seam (splice) between rolls.
In the coating itself, high-speed equal productivity is increased, but the extrusion coating head itself must be moved to pass through the splice part, and the length of the base that passes during this time becomes an uncoated part. , And loss.
If the application speed is increased by 1.5 times and the same time is spent passing through the splice section, it is a simple story, but the loss is also increased by 1.5 times. Even if productivity is improved by increasing the coating speed, this is irrational.

[0005] In that case, the time for passage through the splice portion may be shortened, but the mechanical strength must be maintained in order to maintain the slit gap of the extrusion coating head itself that is precisely controlled. It is a structure that is considerably heavy in weight, and it is practically difficult to reduce the speed to 1 second or less due to the weight, even if the movement of a cylinder or the like for movement is to be accelerated.

[0006] In addition, at least about 10 seconds are required when washing the paint discharge section of the extrusion coating head when the paint passes through the splice section between the rolls (such as wiping a place where the paint spills when leaving). It is. When considered in this way, how to solve the two aspects of productivity improvement by increasing the speed and increase in defects at the splice portion is the key to achieving high-speed coating.

[0007]

In order to solve the above contradictory problem, an attempt was made to temporarily reduce the speed before and after the splice. However, the operation is not simply performed, and even if an operation of increasing or decreasing the amount of paint supply compared to the application speed is performed on the reduced speed portion and the reaccelerated portion, the portion becomes a defective portion due to uneven thickness in the width direction. As a result, the yield in the length direction did not improve.

[0008] Then, the present inventors further examined the behavior in detail, and found that certain factors were also changing at the same time. In other words, when the coating speed is changed while maintaining a constant coating film thickness, the optimum coating portion tension value also changes at the same time, and not only does the coating amount increase or decrease compared to the speed, but also the coating portion tension increases. You have to control it.

The present inventors have collected data on the optimum tension at the application portion with respect to the speed change when the coating thickness is constant for each coating material to be applied. In this method, the speed is changed as a constant coating thickness, and the application portion tension is changed at the same speed. The thickness in the width direction of the sample thus prepared was measured with a film thickness meter, and the condition where the thickness was the most uniform was determined as the optimum application portion tension value. These were programmed and the experiment was performed by changing the application section tension control system so that the application section tension could be varied according to the actual speed of the application line. As a result, the following configuration
Adopted to greatly reduce splice waste
I found that I can do it. That is, the present invention
Do not support the back of the running web,
Press the extrusion-type coating head relatively to
Extrude the coating solution through at least one slit of the pad
A method of applying to a web by using 450 to 600 m /
seam between rolls when applying continuously at high speed
(Splice) Reduce coating speed prior to passage and / or
Or increase the coating speed after passing
When the speed changes, the supply amount and tension become constant.
Of manufacturing a magnetic recording medium characterized by the following adjustment
Is the law.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The following is a specific description of the preferred embodiments. (Example 1) Using audio paint A, width 520 mm,
After drying on a base film having a thickness of 8 μm at a speed of 450 m / min, application was performed so that the coating film thickness was 4.7 μm, and two rolls each having a base film length of 5000 m were continuously applied. At this time, the application part tension was set as follows.

T = 0.036V-3.2 Here, T is tension [kg / width], and V is coating speed [m / m].
in]. In splicing between rolls and rolls, deceleration is started at the remaining 100 m of the preceding roll, and the speed is reduced to 200 m / mi at a deceleration of 0.3 m / s ^2.
n, splicing, moving the extrusion coating head at the same time as splicing with the unwinder,
The discharge of the paint was stopped, and the lip was cleaned. The moving time of the coating head required 10 seconds to return to the home position, and when the coating head returned, the discharge of the paint was restarted. 4 seconds from the timing has returned to the home position is traveling at 200 meters / min, thereafter, accelerated by acceleration 0.3m / s ^2, 450m / mi
n was a constant speed. At this time, it took 4 seconds from the restart of the discharge of the paint to the stabilization of the flow rate. For the amount of paint supply in the acceleration / deceleration range, change the rotation speed of the paint supply pump.
The amount of paint discharged during deceleration in proportion to the speed
Was controlled by increasing the discharge amount of the paint during acceleration so that the film thickness was constant.

(Comparative Example 1) Coating was performed under the same conditions as in Example 1 except that the set tension was fixed at 13 kg / width. Also at this time, after the paint is discharged again, 4
It took seconds.

(Comparative Example 2) The tension was set constant at a set tension of 13 kg / width.
As in Example 1, two rolls were continuously applied at a coating speed of 450 m / min without deceleration and acceleration. At this time, the moving time of the extrusion coating head was 10 seconds. At this time, it took 4 seconds after the paint was discharged again until the flow rate became stable. Table 1 shows the results.

[0014]

[Table 1]

In the first embodiment, a loss of 47 m corresponding to the traveling length of the coating head moving time and the time from the re-discharge of the paint to the stabilization is sufficient.
Thickness unevenness in the width direction occurred in the portion where the deceleration started, the portion where the speed became constant at 200 m / min, and the portion where the acceleration was accelerated, and an extra 150 m was lost as compared with Example 1.

In Comparative Example 2 in which the coating was performed without deceleration, the travel time of the coating head and the length traveled during the period from the re-discharge of the coating to the stabilization of the coating were equivalent to 105.
m.

As is clear from the results, if the method of accelerating and decelerating at the splice portion and changing the paint supply amount and the coating portion tension according to the coating speed is adopted, the loss length of the raw material can be shortened.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-47-3437 (JP, A) JP-A-54-34343 (JP, A) JP-A-60-157727 (JP, A) JP-A-4- 35766 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) G11B 5/842-5/848 B05D 1/26

Claims (3)

(57) [Claims] 1. A method in which an extrusion-type coating head is pressed relatively to a web while not supporting a rear surface of a running web, and a coating liquid is extruded from at least one slit of the coating head to apply the coating liquid to the web. Oh, 4
When performing continuous coating at a high speed of 50 to 600 m / min, the coating speed is lowered and the supply amount and tension are kept constant before the roll passes through a splice.
A method for manufacturing a magnetic recording medium, characterized in that adjustment is made so that (2) The back of the running web is not supported
Press the extrusion coating head relatively to the web
From at least one slit of the coating head
A method of extruding a coating solution and applying the solution to a web,
Coating is performed continuously at a high speed of 50 to 600 m / min.
The coating speed after passing the splice between rolls
The feed rate and tension are increased and the coating thickness is constant.
Manufacturing method of magnetic recording medium characterized by adjusting
Law. (3) The back of the running web is not supported
Press the extrusion coating head relatively to the web
From at least one slit of the coating head
A method of extruding a coating solution and applying the solution to a web,
Coating is performed continuously at a high speed of 50 to 600 m / min.
Before passing through the joint (splice) between rolls,
Reduce the cloth speed, increase the coating speed after passing
In addition, the feed rate and the tension during these speed changes
Magnetic recording characterized by adjusting so as to be constant
The method of manufacturing the medium.