JPH11345417A - Hot roll device for magnetic tape - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hot roll device for a magnetic tape by which no folded edge is generated even when the magnetic tape is subjected to a hot roll treatment at a high temp. and a moderate negative cupping state can be surely and efficiently obtained with improved productivity is. SOLUTION: In the hot roll device for the magnetic tape which makes the magnetic tape 1 travel along an outer periphery of a heat roll 11 and is provided with a nip roll 12 for pressing the magnetic tape 1 to the heat roll 11, the width of the pressing part 14 of the nip roll 12 is made to be narrower than the width of the magnetic tape 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a hot roll device for a magnetic tape. More specifically, the present invention relates to a hot roll device for a magnetic tape in which a magnetic tape runs around the outer periphery of a heat roll and the magnetic tape is pressed by a nip roll.

[0002]

2. Description of the Related Art In a manufacturing process of a magnetic recording medium such as a magnetic tape, a magnetic metal is vapor-deposited on a base film made of a resin material such as PET to form a vapor-deposited tape. And a lubricant. This vapor deposition tape is cut into a predetermined tape width to produce a magnetic tape. In such a manufacturing process, the evaporated tape shrinks as the metallized film is cooled, so that the entire tape is deformed concavely on the side with the metallized film, that is, on the magnetic surface side. Will come.

FIG. 9 is a partial perspective view of a vapor deposition tape whose magnetic surface is deformed into a concave shape. As shown,
The tape 1 is deformed so that the magnetic surface 2 of the vapor deposition tape 1 is concave inward. Since such a warpage of the magnetic surface affects the head contact characteristics, it is necessary to numerically grasp the degree of the warpage.

FIG. 10 is a schematic diagram of a cupping value measuring method for quantifying such a degree of warpage. To measure the degree of warpage, the height of three points in the width direction was measured with an optical microscope while applying a load of 1 g to both ends of a 50 mm long tape cut into 8 mm width, and the average of both ends and the center of the center were measured. Calculate the height difference. The value obtained in this way is called a cupping value, and is one of the indices indicating the characteristics of the vapor deposition tape.

At this time, a state in which the warpage is concave on the magnetic surface is represented by a positive sign, and a state in which the magnetic surface is convex is represented by a negative sign. A completely flat state has a cupping value of zero. The fact that the magnetic tape side is deformed into a concave state on the magnetic surface side, that is, in a state of normal cupping, causes deterioration of head contact characteristics described later, and it is necessary to correct this. The ideal cupping value range in the head contact characteristics is -0.8 mm to -0.0 mm.
It has been confirmed that the distance is about 3 mm.

FIG. 11 and FIG. 12 are explanatory diagrams of definitions of head contact characteristics of a tape. As shown in FIG. 11, when the switching pulse a is applied to the magnetic tape, the ratio B / A × 100 of the output A on the entrance side and the output B on the exit side with reduced output in the RF waveform of the reproduced output voltage. %)
Is defined as a head contact characteristic. As shown in FIG. 12, the head contact characteristics become better (closer to 100%) as the cupping value becomes negative. Positive cupping tapes have a problem in that the contact with the head during reproduction is poor, leading to a reduction in head contact characteristics. Therefore, usually, the base is shrunk by performing a hot roll treatment to correct the magnetic surface of the tape to a convex state, that is, a moderate negative cupping state.

FIG. 13 is a sectional view of a main part of a conventional hot roll device. In this hot roll device, the tape 1 is wound so that the magnetic surface 2 is in contact with the metal heat roll 3, and is further pressed by the heat-resistant rubber nip roll 4, and the heat of the heat roll 3 is directly transmitted to the tape 1. Conventionally, the width of the pressing portion 5 which is the tape contact portion of the nip roll 4 is set to be equal to or slightly larger than the tape width. The higher the hot roll processing temperature, the more the negative cupping state progresses.

FIG. 14 is a partial perspective view of a magnetic tape whose magnetic surface has been corrected to have a convex shape. As shown in the figure, by applying the magnetic tape 1 to a hot roll device, the tape magnetic surface 2 is corrected from a concave shape to a convex shape, and a negative cupping state is obtained.

[0009]

However, at the time of hot roll processing, although the cause is not clear, cupping is strongly applied to both ends of the tape as compared with the center portion of the tape, and when a certain temperature is exceeded, both ends of the tape curl. When the tape is wound, both ends are depressed, resulting in a so-called broken ear.

FIG. 15 is a partial perspective view of the tape in such a folded state, and FIG. 16 is a graph showing the cupping value with respect to the position of the tape width after the conventional hot roll processing. In FIG. 16, a represents no hot roll processing,
b shows a graph at a hot roll processing temperature of 150 ° C., and c shows a graph at a hot roll processing temperature of 200 ° C. In addition, x indicates that the cupping value cannot be measured, that is, the ear is broken.

In the case of a without the hot roll, the cupping value becomes positive in any part of the tape, which causes a decrease in head contact characteristics. In the case of b at a hot roll of 150 ° C., the cupping value at both side edges of the tape is a good negative value, but the cupping value near the center position of the tape width is not a good value. When the temperature was further increased and the temperature was 200 ° C., a good cupping value was measured for the entire tape, but a break occurred at both side edges of the tape.

Since the occurrence of creases is fatal in the production of the tape, hot roll processing must be performed at a temperature at which creases do not occur. For this reason, even when sacrificing the cupping correction effect by the hot roll treatment, the hot roll treatment at a low temperature may be inevitable, and an immediate improvement has been desired.

The present invention has been made in view of the above-mentioned prior art, and does not cause breakage even when a magnetic tape is hot-rolled at a high temperature, so that an appropriate negative cupping state can be efficiently obtained without fail. It is an object of the present invention to provide a magnetic tape hot roll device with improved productivity.

[0014]

According to the present invention, there is provided a magnetic tape having a nip roll for running a magnetic tape along an outer periphery of a heat roll and pressing the magnetic tape against the heat roll. A width of a pressing portion of the nip roll is smaller than a width of the magnetic tape.

According to this structure, the heat load on the both side edges of the magnetic tape can be reduced while sufficient heat is applied to the center of the tape, so that the magnetic tape does not break at a high temperature. A sufficient corrective action can be obtained effectively.

In a preferred embodiment, the width of the magnetic tape is about 500 mm, and the nip rolls are formed on both side edges of the magnetic tape at a width of about 10 mm to 15 mm, respectively.
Characterized by having a non-contact portion.

According to this configuration, since the heat load from the nip roll is not applied to the non-contact portions on the both side edges of the magnetic tape, the ear is not broken and a sufficient correcting effect is obtained without wrinkles and the like. It is possible to produce a tape with good hitting characteristics.

[0018]

FIG. 1 is a schematic diagram of a magnetic tape hot roll apparatus according to an embodiment of the present invention. The tape 1 is unwound from the unwinding unit 10, and the tape 1 is wound around the heat roll 11 with its magnetic surface facing.
The tape 1 comes into contact with the outer circumference of the holding angle α of the heat roll 11 and travels as shown by the arrow B with the heat roll 11 which rotates as shown by the arrow A. At this time, the tape 1 is pressed toward the heat roll by a nip roll 12 made of heat-resistant rubber, and the heat of the heat roll 11 is directly transmitted to the tape 1. Thereafter, the tape 1 is wound around the winding unit 13.

FIG. 2 is a sectional view of a main part of the hot roll device according to the embodiment of the present invention. As shown in the drawing, the width of the pressing portion 14 of the nip roll 12 was made smaller than the width of the tape 1, and the contact portion between the nip roll 12 and the tape 1 was reduced. Specifically, both side edges of the pressing portion are 10-15
The non-contact portion 15 with the tape 1 was provided by narrowing by about mm.

As a result, the nip roll 12 does not come into contact with both ends of the tape where breaks occur, so that the heat load on both ends of the tape is reduced while sufficient heat is applied to the center of the tape, and the breaks of the breaks occur. It is possible to prevent occurrence.
In this case, it is considered that the cupping effect at both ends of the tape is reduced because the pressing force is no longer applied to both ends of the tape, but there is no problem because about 30 mm at both ends of the tape is a portion not used as an actual magnetic tape.

Hereinafter, test results obtained by performing a hot roll process using a nip roll under various conditions will be described. In the test, hot roll treatment was performed while gradually increasing the heat roll temperature, and the upper limit temperature at which ear breakage occurred was investigated. At the same time, the test was performed while measuring cupping.

FIG. 3 is a diagram showing the dimensions of the nip roll used in this test, and FIG. 4 is a flow chart of a trial production process of the tape used in this test.

The first test is as follows. First,
Co was deposited to a thickness of 200 nm on a PET base having a thickness of 6 μm and a width of 500 mm (S1). A 10 nm carbon layer was applied to this by DC sputtering (S2).
Further, a back layer comprising a binder and carbon particles was applied to the back surface side of the base (S3). Using this as a sample tape, a hot roll processing test was performed (S
4). It has been confirmed from previous studies that changing the wrap angle, processing speed, and tension of the heat roll during hot roll processing does not substantially change the amount of cupping and edge breakage. I have a test.

In this test, a hot roll processing speed of 10
0 m / min, a heat roll diameter of 300 mm, a heat roll holding angle of 90 °, and a tape tension of 5 kg / 500 mm both before and after the nip of the hot roll. The roll diameter of the nip roll 12 is 100 mm, heat-resistant fluoro rubber (Viton hardness 55 °) is used as a material, and several types of nip rolls in which only the width of the tape contact portion (pressing portion 14) is changed are prepared and a hot roll processing test is performed. Was. In the test, the presence or absence of occurrence of ear breaks was confirmed while changing the temperature, and the center of the tape was cut out into a width of 8 mm to measure cupping. Further, with respect to the sample in which cupping could be corrected most negatively in the range where ear break did not occur under each nip roll condition, a fluorine-based lubricant was applied to both sides of the tape (S
5, S6), after cutting to 6.35 mm (S7), DV
It was incorporated in a cassette (S8) and the hitting characteristics were evaluated. The measurement is a DV deck DHR-1000 for Sony home appliances.
Then, the drop amount of the exit side of the RF waveform (see FIG. 11) was measured. The test was performed by preparing a sample in which the width d (FIG. 3) of the non-contact portion 15 of the nip roll 12 was changed in five steps from 0 to 20 mm.
The test was performed under three conditions of 150 ° C. The test results are shown in Table 1 below.

[0025]

[Table 1]

As can be seen from Table 1, by setting the non-contact portion of the nip roll wide, it is possible to suppress the occurrence of breakage even when a high-temperature hot roll treatment is performed. However, wrinkles occurred on the tape during the test of Example 3,
Therefore, the width of the non-contact part is 10 to 10 in consideration of the nip effect.
It is appropriate to suppress it to about 15 mm.

FIGS. 5 and 6 are graphs showing the results of the first test. FIG. 5 is a graph showing a minimum cupping value for a non-contact portion under different temperature conditions on a PET basis, and FIG. 6 is a graph showing a maximum head contact characteristic for a non-contact portion under different temperature conditions on a PET basis. . 5 and 6, it can be seen that both the cupping value and the head contact characteristics are good when the non-contact portion d is 10 mm or more. However, when the non-contact portion d is 20 mm, wrinkles are generated on the tape. Therefore, it is considered that the length of the non-contact portion d is preferably about 10 to 15 mm.

Next, as a second test, a test using an aramid base instead of a PET base was performed. Aramid base is a promising base for next generation data and video format media. This aramid base is characterized by a high heat resistance temperature, and can obtain strength even with a very thin thickness of about 4.0 to 5.0 μm. Therefore, when incorporated in a cassette or the like, there is an advantage that the recording density per unit area can be improved as compared with the bases of other types.

In the test, Co was deposited to a thickness of 200 nm on an aramid base having a thickness of 5 μm and a width of 500 mm.
A 10 nm carbon layer was deposited by C sputtering. Further, a back layer comprising a binder and carbon particles was applied to the back surface side of the base. Using this as a sample tape, a hot roll processing test was performed.

The holding angle of the heat roll, the processing speed, and the tension in the hot roll processing were performed under the same conditions as in the first test. That is, hot roll processing speed 100
m / min, heat roll diameter 300 mm, heat roll hugging angle 90 °, and tape tension were set at 5 kg / 500 mm both before and after the nip of the hot roll. The nip roll dimensions used for the hot roll processing were the same as in the first test, and the test method was also the same.

In the second test, a sample was prepared by changing the width d of the non-contact portion of the nip roll 12 in five steps from 0 to 20 mm in the same manner as in the first test. 150 ° C, 200 ° C, 25
The test was performed under three conditions of 0 ° C. The test results are shown in Table 2 below.

[0032]

[Table 2]

As can be seen from Table 2, by setting the non-contact portion d of the nip roll to be wide, it is possible to suppress occurrence of ear breakage even when hot roll processing is performed at a high temperature. However, as in the first test, wrinkles occurred on the tape during the test of Example 3, and the width of the non-contact portion was 10
It is appropriate to keep it to about 15 mm.

FIGS. 7 and 8 are graphs showing the results of the second test. FIG. 7 is a graph showing a minimum cupping value for a non-contact portion due to a difference in temperature conditions on an aramid base, and FIG. 8 is a graph showing a maximum head contact characteristic for a non-contact portion when a temperature condition is different on an aramid base. . Again, the non-contact part d is 10
When the non-contact portion d is 20 mm, the length of the non-contact portion d is about 10 to 15 mm as in the first test because wrinkles occur on the tape when the non-contact portion d is 20 mm. Is considered desirable.

In the second test, the heat resistant temperature is high (2
50 ° C) Due to the use of aramid type base, 20
At a temperature of 0 ° C. or less, a sufficient hot roll straightening effect cannot be obtained. Therefore, it can be seen that a sufficient hot roll straightening effect can be obtained only by using the nip roll of the present invention, which does not cause ear breakage even at a high temperature treatment of 200 ° C. or more.

[0036]

As described above, in the present invention,
Because the non-contact portion with the tape is provided on both sides of the nip roll, sufficient heat can be applied to the center of the tape to reduce the heat load on both ends of the tape, causing the tape to break. In addition, a sufficient correcting action can be obtained effectively at a high temperature, and a tape having good head contact characteristics can be efficiently produced, thereby improving productivity.

[Brief description of the drawings]

FIG. 1 is a schematic view of an entire hot roll device for a magnetic tape according to an embodiment of the present invention.

FIG. 2 is a sectional view of a main part of the hot roll device according to the embodiment of the present invention.

FIG. 3 is a diagram showing dimensions of a nip roll used in a test.

FIG. 4 is a flowchart of a tape manufacturing process used in the test.

FIG. 5 is a graph showing a minimum cupping value of a first test result.

FIG. 6 is a graph showing the maximum value per head of the first test result.

FIG. 7 is a graph showing a minimum cupping value of a second test result.

FIG. 8 is a graph showing a maximum value per head characteristic of a second test result.

FIG. 9 is a partial perspective view of a magnetic tape having a concave magnetic surface.

FIG. 10 is a schematic explanatory view of a cupping value measuring method.

FIG. 11 is an explanatory diagram of definitions of head contact characteristics.

FIG. 12 is a graph showing head contact characteristics with respect to a cupping value.

FIG. 13 is a sectional view of a main part of a conventional hot roll device.

FIG. 14 is a partial perspective view of a magnetic tape having a convex magnetic surface.

FIG. 15 is a partial perspective view of the tape in a broken ear state.

FIG. 16 is a graph showing a cupping distribution in a tape width direction.

[Explanation of symbols]

1: tape, 2: magnetic surface, 10: unwinding part, 11: heat roll, 12: nip roll, 13: winding part, 1
4: pressing part, 15: non-contact part.

Claims (2)

[Claims] 1. A magnetic tape hot roll device comprising a nip roll for moving a magnetic tape along an outer periphery of a heat roll and pressing the magnetic tape against the heat roll, wherein a width of the pressing portion of the nip roll is A hot roll device for magnetic tape, wherein the width is smaller than the width of the magnetic tape. 2. The magnetic tape according to claim 1, wherein the width of the magnetic tape is about 500 mm, and the nip roll has a non-contact portion having a width of 10 mm or more and 15 mm or less at both side edges of the magnetic tape. Hot roll device for magnetic tape.