JPH07141651A - Production of metal thin film magnetic recording medium - Google Patents

Abstract

PURPOSE:To decrease dropout and to suppress disturbance in an image due to clogging of a head by suppressing a ruggedness of the surface of a magnetic recording medium after a magnetic layer is formed and suppressing cracks due to a rugged surface. CONSTITUTION:In the production process of a magnetic recording medium after a magnetic layer is formed, a buffing member 6 is traveled in contact with the surface of a press roller 5 such as a nip roller and touch roller. The buffing member 6 is traveled at the angle of 10-60 degree to the traveling direction of the magnetic recording medium 1. By this constitution, a ruggedness of the surface of the medium and cracks due to the ruggedness are suppressed, so that dropout is decreased and disturbance of the image due to clogging can be suppressed.

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 metal thin film type magnetic recording medium used as a video tape, an audio tape, a computer tape or the like.

[0002]

2. Description of the Related Art Recent video tape recorders (hereinafter referred to as VT
The development of (abbreviated as R) is in the direction of higher image quality. As a tape for achieving this, a conventional magnetic powder is dispersed in a binder resin to form a magnetic layer on a coating type magnetic recording medium, and a magnetic layer is formed by vacuum deposition of a magnetic metal having a high recording density. Formed metal thin film magnetic recording media have been developed. However, if the recording density is increased in order to achieve high image quality, there will be no problems such as floating dust on the tape surface and deposits or irregularities such as falling powder from the end of the medium, which have not been a problem until now (below. Appears as DO). Therefore, in order to realize high image quality, it is necessary to improve the recording density and also reduce the DO. From this point of view, a method has been proposed in which the magnetic recording medium is brought into contact with an abrasive tape to run to burnish the surface of the medium. The effect of reducing the adhered substance is large, but the effect of unevenness is hardly obtained. In particular, in practical use with a VTR, the concave portion on the surface of the magnetic layer has a signal loss only in that portion, whereas the convex portion causes the head to float and the signal loss in a very wide range. Therefore, to reduce DO,
It is important to suppress the generation of protrusions on the surface of the magnetic recording medium.

The unevenness of the tape surface is generated in each manufacturing process such as magnetic layer formation, back coat layer formation, lubrication layer formation, and slitting. The contents of occurrence are roughly classified into the following two.

One is generated in the magnetic layer forming step.
FIG. 2 shows a schematic diagram of a conventional magnetic layer forming process. In a vacuum, the non-magnetic support 11 is delivered from the delivery roll 12, is closely transferred to the surface of the cooling support roller 13, and is wound up by the winding roll 14. The magnetic layer is formed by evaporating a magnetic material on the surface of the non-magnetic support 11 from the evaporation source 15 on the cooling support roller 13 by the vapor flow 17 controlled by the mask 16. At this time, if there is an adhered matter or a scratch on the cooling support roller 13, at the moment when the vapor flow 17 reaches the non-magnetic support 11, that part of the non-magnetic support loses heat and is deformed, resulting in unevenness. Let FIG. 3 shows a conceptual diagram of a magnetic recording medium convex portion generated in the conventional magnetic layer forming step. FIG. 3 (c) shows the adhered matter 1 on the cooling support roller 13.
When the vapor flow 17 arrives, the non-magnetic support 11 on the deposit 18 is not cooled when there is 8, and the heat instantaneously deforms to become FIG. 3 (d). After this, the magnetic layer 19 is formed on the non-magnetic support 11 to form the convex portion of FIG. Similarly, if there is a scratch on the surface of the cooling roller,
Contrary to the above, it becomes a concave portion. A method for removing the above-mentioned deposit is disclosed in Japanese Patent Application Laid-Open No. 5-73905.

The other is generated in each step from the formation of the back coat layer to the slitting. Figure 4
FIG. 1 shows a schematic view of a conventional running tension adjusting device for a magnetic recording medium. The magnetic recording medium 1 travels with the roller 2, the driving roller 3, and the roller 4, and is pressed by the pressing roller (hereinafter referred to as a nip roller) 5 on the driving roller 3, and the traveling tension of the magnetic recording medium 1 is before and after the driving roller 3. Is adjusted. Further, FIG. 5 shows a schematic view of a conventional winding device for a magnetic recording medium. In each of the above steps, the processed magnetic recording medium 1 travels on the roller 21 and is wound up by the winding roll 22. At this time, the pressure roller (hereinafter referred to as the touch roller) 20 is pressed and wound up to prevent the entrainment of air. If there is an adhering substance on the surface of the nip roller or the touch roller, the shape of the adhering substance is transferred to the magnetic recording medium by pressing the roller, and appears as unevenness. The unevenness after the formation of the magnetic layer does not contain a binder resin in the magnetic layer unlike the coating type magnetic recording medium, and therefore cracks occur in the magnetic layer during transfer. FIG. 6 shows a conceptual diagram of the concavities and convexities generated in the conventional magnetic recording medium. FIG. 6 (f) shows the unevenness when the adhered matter on the surface of the pressing roller transfers the shape from the magnetic layer 19 side.
Since the magnetic recording medium is running, when the shape is transferred, the magnetic layer portion having a crack is displaced, and the unevenness appears as shown in the figure. Further, FIG. 6G shows a convex portion generated from the opposite surface of the magnetic layer 19, and a crack is similarly formed in the magnetic layer. In the figure, 11 is a non-magnetic support.

[0006]

In the two types of irregularities roughly classified above, when these are processed into tape and run on a VTR or the like, in the former, only the peripheral portion of the concave or convex appears as DO. On the other hand, in the latter case, in addition to the peripheral part of the concavities and convexities becoming DO, the cracked part in the magnetic layer peels off and doubles the DO. Furthermore, the peeled pieces cause head clogging, which disturbs the image and makes it unusable. Therefore, it is important to suppress the latter unevenness.

The present invention solves the above problems and suppresses the irregularities on the surface of a magnetic recording medium after the formation of a magnetic layer and the cracks in the magnetic layer that occur at that time, thereby reducing DO and disturbing the image due to head clogging. An object of the present invention is to provide a method for manufacturing a metal thin film type magnetic recording medium that suppresses the above.

[0008]

In order to solve the above-mentioned problems, the metal thin film magnetic recording medium manufacturing method according to the present invention presses the magnetic recording medium on the drive roller in the manufacturing process after forming the magnetic layer. Manufactured by making a buffing member come into contact with the surface of the pressing roller while running, in which case the buffing member makes contact with the pressing roller at an angle of 10 to 60 degrees with respect to the running direction of the magnetic recording medium. Is.

[0009]

The driving roller for adjusting the traveling tension of the magnetic recording medium is a metal roller, whereas the nip roller and the touch roller are resin rollers. Almost all the deposits on the roller are attached by static electricity, so it is possible to prevent the deposit on the metal roller by removing the static electricity.However, it is difficult to prevent the deposit on the resin roller. It cannot be removed without scraping. At this time, a polishing tape in which abrasive grains are hardened with a binder to form a polishing layer is generally used.However, when scraping off adherents, the surface of the resin roller is damaged, and when the magnetic recording medium runs, dust is generated from that part. It has the opposite effect. Therefore, cotton non-woven fabric,
By using a buffing member such as cotton cloth, felt, or sisal hemp, the deposit can be removed without damaging the roller. However, when the tension is applied in the traveling direction due to the uneven thickness and the variation in the density of the buffing member, the buffing member is wavy, and a portion where the contact state with the surface of the pressing roller is bad in the width direction of the buffing member occurs. Since the portion in poor contact is continuously generated in the running direction of the buffing member (rotational direction of the pressing roller), it is impossible to remove the deposits on that portion. Here, the buffing member is set to 1 with respect to the running direction of the magnetic recording medium (the rotating direction of the pressing roller).
By causing the buffing member to travel in contact with the surface of the pressing roller at an angle of 0 to 60 degrees, even if the buffing member is wavy in the traveling direction, the portion in poor contact with the surface of the pressing roller does not continue, so that the entire surface of the pressing roller is attached. You can remove the kimono. Therefore, it is possible to suppress the occurrence of irregularities on the surface of the metal thin film type magnetic recording medium and the accompanying cracks in the magnetic layer, to reduce DO and to prevent the image from being disturbed due to head clogging.

[0010]

An embodiment of the present invention will be described in detail below.

On one surface of a non-magnetic support made of a polyethylene terephthalate film having a thickness of 10 μm and a width of 200 mm, Co--N was added in oxygen of 4 to 7 × 10 ^-5 Torr.
i (Ni: 15 wt%) was evaporated to a thickness of about 0.2 μm to form a magnetic layer. Then, a perfluorocarboxylic acid type lubricant was applied to the surface of the magnetic layer under the condition of 10 mg / m ² to form a lubricating layer. Further, a back coat layer having a thickness of 0.5 μm was formed on the non-magnetic support opposite to the magnetic layer by using a material in which carbon black was dispersed in a binder resin. This magnetic recording medium was slit to a width of 8 mm to prepare an evaluation tape. At this time, the following steps were performed in the manufacturing process after the formation of the magnetic layer.

FIG. 1 is a schematic view of a nip roller cleaning device of a running tension adjusting device for a magnetic recording medium according to the present invention. 1A is a front view and FIG. 1B is a plan view. The magnetic recording medium 1 travels in the direction of the arrow with the roller 2, the driving roller 3, and the roller 4. The magnetic recording medium 1 is
The nip roller 5 presses the drive roller 3 with a pressure of 1.5 kg. The buffing member 6 is unwound from the unwinding roll 7, travels with the roller 8, the nip roller 5, and the roller 9, and is wound up by the winding roll 10. At this time, the buffing member 6 is running in the direction of the arrow at an angle of θ with respect to the running direction of the magnetic recording medium 1. In this example, the magnetic recording medium was run at a speed of 30 m / min so that the magnetic layer was on the nip roller side. Further, a non-woven fabric of 100% cotton was used as the buffing member, and contact travel was performed while changing θ at a speed of 50 mm / min and a wrap angle of 90 degrees with respect to the nip roller. Under the same conditions, the touch roller at the time of winding as shown in FIG. 5 was also cleaned at the same time.

As comparative samples, those in which the nip roller and the touch roller were not cleaned and the buffing member was θ
= 0 degree, nip roller and touch roller were made to run, cooling support roller with a particle size of 3 μm when forming a magnetic layer
Those obtained by polishing with the polishing tape using the abrasive grains of No. 1 and not cleaning the roller in the subsequent steps were prepared as Comparative Example 1, Comparative Example 2 and Comparative Example 3, respectively.

These tapes were evaluated for the following items. The results are shown in (Table 1).

(1) Dropout (DO) Using an 8 mm VTR (manufactured by Sony, EV-S900),
A signal loss of 15 μs in length and 16 dB or more in depth was measured as DO.

(2) Image evaluation Recording and reproducing with a VTR, and visually observing a momentary disturbance of a television image due to head clogging. If the disturbance does not occur ◎ Disturbance per minute is once Those with less than 1 were evaluated as ◯, and those with one or more disturbances per minute were evaluated as x.

[0017]

[Table 1]

As described above, in the metal thin film type magnetic recording medium according to the manufacturing method of the present invention, the unevenness of the magnetic layer and the cracks of the magnetic layer which are generated therewith are suppressed, and the image due to the reduction of DO and the clogging of the head is generated. Suppress the disturbance. When θ is smaller than 10 degrees, the effect of reducing unevenness is small due to the non-uniform contact between the buffing member and the pressing roller, and
When θ is larger than 60 degrees, the buffing member travels unstablely and the contact state with the pressing roller becomes non-uniform, so that the effect of reducing unevenness is reduced.

In the present invention, a non-woven fabric made of 100% cotton is used as the buffing member, but the same effect can be obtained by using cotton cloth, felt, sisal or the like.

[0020]

As described above, according to the present invention, a buffing member is provided on the surface of a pressure roller such as a nip roller or a touch roller in the magnetic recording medium manufacturing process after the formation of the magnetic layer in the direction of travel of the magnetic recording medium. A metal thin film magnetic recording medium in which irregularities on the surface of the medium and cracks of the magnetic layer caused thereby are suppressed by contact traveling at an angle of -60 degrees, and DO is reduced and image distortion due to head clogging is suppressed. Can be provided.

[Brief description of drawings]

FIG. 1 is a schematic view of a nip roller cleaning device of a running tension adjusting device for a magnetic recording medium of the present invention.

FIG. 2 is a schematic view of a conventional magnetic layer forming process.

FIG. 3 is a conceptual diagram of a convex portion of a magnetic recording medium generated in a conventional magnetic layer forming process.

FIG. 4 is a schematic view of a conventional running tension adjusting device for a magnetic recording medium.

FIG. 5 is a schematic view of a conventional magnetic recording medium winding device.

FIG. 6 is a conceptual diagram of irregularities generated in a conventional magnetic recording medium.

[Explanation of symbols]

 1 Magnetic Recording Medium 2, 4, 8, 9, 21 Roller 3 Driving Roller 5, 20 Pressing Roller 6 Buff Polishing Member 7, 12 Feeding Roll 10, 14, 22 Winding Roll 11 Nonmagnetic Support 13 Cooling Support Roller 15 Magnetic material evaporation source 16 Mask 17 Vapor flow 18 Adhesion 19 Magnetic layer

Claims (1)

[Claims] 1. A metal thin film type magnetic recording medium in which a magnetic layer made of a metal thin film is formed on a non-magnetic support, and the magnetic recording medium is pressed on a drive roller in a magnetic recording medium manufacturing process after the magnetic layer is formed. A method of manufacturing a metal thin film type magnetic recording medium, which comprises manufacturing a magnetic recording medium while causing a buffing member to travel while contacting a pressing roller that is in contact with the running direction of the magnetic recording medium at an angle of 10 to 60 degrees.