JPH0562187A - Manufacture of magnetic recording medium - Google Patents

Abstract

PURPOSE:To reduce a dropouts due to the defects of a magnetic recording layer and to enhance the reliability and the quality of a recording operation by a method wherein a foreign body existing on the formation face of the magnetic recording layer on a synthetic resin base body is removed in advance and the magnetic recording layer is then formed. CONSTITUTION:Before a metal thin-film magnetic recording layer is formed on a synthetic resin base body, a foreign body on the face, on which at least the magnetic recording layer is formed, of the synthetic resin base body is removed by using a knife blade or a lapping tape. The synthetic resin base body is formed of polyethylene terephathalate(PET). Consequently, defects, of the magnetic-recording layer, which is caused by the foreign body is reduced sharply, and it is possible to effectively reduce dropouts.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a magnetic recording medium. More specifically, the present invention relates to improvement of surface properties of a magnetic recording medium having a metal thin film type magnetic recording layer on a synthetic resin substrate.

[0002]

2. Description of the Related Art In a magnetic recording medium, a claim for recording difference caused by a defect in a magnetic recording layer or adhesion of foreign matter,
That is, dropout is a serious problem. In particular,
When shortening the wavelength or narrowing the track for the purpose of higher density, even a minute defect or foreign matter which has not been a problem in the past can cause a dropout, which is of great concern.

Therefore, it has been proposed to remove foreign matter by cleaning the surface of the magnetic recording medium with a knife blade or a nonwoven fabric. However, this method has a great effect in the case of a coating type magnetic recording medium in which many dropouts due to foreign matters occur, but it has no effect on defects in the magnetic recording layer. In particular, in the metal thin film type magnetic recording medium, since dropouts due to defects in the magnetic recording layer are large, the dropout cannot be sufficiently reduced by the above method.

[0004]

SUMMARY OF THE INVENTION The present invention solves the disadvantage of dropout due to defects in the magnetic recording layer of the above conventional products, and thus provides a magnetic recording medium excellent in recording reliability and quality. To aim.

[0005]

In order to achieve the above object, the present invention provides a method for manufacturing a magnetic recording medium, which comprises forming a metal thin film magnetic recording layer on a synthetic resin substrate. The method for producing a magnetic recording medium is characterized in that, before forming, the foreign matter on at least the surface of the synthetic resin substrate on which the magnetic recording layer is formed is removed with a knife blade or a wrapping tape.

[0006]

According to the method of the present invention, the magnetic recording layer is formed after the foreign substances existing on the magnetic recording layer forming surface of the synthetic resin substrate are removed in advance. It is greatly reduced, and dropout can be effectively suppressed.

Although the exact mechanism has not been elucidated yet, it is beyond speculation that most of the defects in the magnetic recording layer are due to foreign substances on the substrate film, especially the synthetic resin oligomer component constituting the substrate adhered to the surface. It seems to be caused. Therefore, before forming the magnetic recording layer, the surface of the synthetic resin substrate on which the magnetic recording layer is to be formed is rubbed with a knife blade or a wrapping tape to scrape off and remove foreign matter mainly composed of oligomers. It seems that the defects will be reduced.

The magnetic recording layer which causes dropout
As the size of foreign substances such as oligomers that cause defects
Has a height of 0.4 μm or more, that is, the foreign matter is assumed to be spherical.
If determined, 0.03 μm³ Those with the above volume,
Even if the height is small, the area occupied on the substrate is 0.7
μm² The above is a problem. Enough dropout
In order to reduce the
Current quantity is 0.3 / cm ² Must be
High reliability recording for high density recording and commercial use
0.05 piece / cm² Preferably below
Yes.

As the material of the knife blade for removing the foreign matter mainly composed of the above-mentioned oligomer, all materials generally used for knives such as stainless steel, sapphire and chrome steel can be used. This blade is pressed against the film surface at an angle within the range of 90 ° to 5 ° so as to be stroked against the running direction of the film.

Alternatively, wrapping tape can be used instead of knife blade. A wrapping tape for such a purpose has a surface roughness of # 300 to # 10.
000 is preferable. If it is rougher than # 300, the surface of the base film may be damaged. On the other hand, # 1
If it is smaller than 0000, there is no sufficient foreign matter removing effect.

As the substrate, PET, PEN, polyethylene, polyimide, polyamide and the like can be processed into a film, and all synthetic resins usable as the substrate of the magnetic recording medium can be used.

The magnetic recording layer is made of Co, Fe, Ni, Co-
Ni alloy, Co-Cr alloy, Co-P alloy, Co-Ni
It can be formed by depositing a ferromagnetic metal or alloy such as -P alloy on the substrate by a known means such as vacuum deposition, ion plating, sputtering and plating.

Magnetic recording media that can be manufactured by the method of the present invention include magnetic tapes and floppy disks.

[0014]

The present invention will be described in more detail with reference to the following examples.

Example 1 A PET film 3 having a thickness of 10 μm was set in a cleaning device schematically shown in FIG. 1, and while traveling at a winding speed of 20 m / min, a sapphire knife blade 1 was placed on the film. The foreign matter mainly composed of the oligomer was scraped off, and immediately after that, the foreign matter was removed by the nonwoven fabric 2. Then, the cleaned film is set in a vacuum vapor deposition apparatus, Co ₈₀ Ni ₂₀ alloy is heated and evaporated under a vacuum of 10 ^-6 Torr, and Co having a thickness of 2000 Å is formed on the base film.
A film having a magnetic recording layer made of a Ni ferromagnetic metal thin film was set in a gravure coating apparatus, and a 0.8 μm-thick back coat layer made of carbon black and synthetic resin was formed on the surface on which the magnetic recording layer was not formed. Further, the magnetic recording layer has a thickness of 150 made of perfluoropolyether.
A lubrication layer of Å was formed. After that, it was cut into a predetermined width to produce a magnetic tape.

Example 2 A PET film 3 having a thickness of 10 μm was set in a cleaning device schematically shown in FIG. 2, and was run at a winding speed of 20 m / min while wrapping tape 4 of # 2000.
The foreign matter mainly composed of the oligomer on the film was scraped off by using the non-woven fabric, and immediately after that, the foreign matter was removed by the nonwoven fabric 2.
Then, the cleaned film is set in a vacuum vapor deposition apparatus, Co ₈₀ Ni ₂₀ alloy is heated and evaporated under a vacuum of 10 ^-6 Torr, and a C film having a thickness of 2000 Å is formed on the base film.
A film having a magnetic recording layer made of an oNi ferromagnetic metal thin film was set in a gravure coating apparatus, and a 0.8 μm-thick back coat layer made of carbon black and synthetic resin was formed on the surface on which the magnetic recording layer was not formed. Further, the magnetic recording layer has a thickness of 150 made of perfluoropolyether.
A lubrication layer of Å was formed. After that, it was cut into a predetermined width to produce a magnetic tape.

Comparative Example 1 A magnetic tape was manufactured in the same manner as in Example except that the cleaning of the base film was omitted.

The magnetic tape produced as described above is
Drop-out was measured with an actual machine by incorporating it into a milliVTR cassette half. In the evaluation, the dropout was determined when the time during which the output decreased by 18 dB was 5 μsec or more. The results are summarized in Table 1 below. Also,
Foreign substance substrate area 1c having a volume of 0.06 μm ³ or more, or an area occupied on the substrate of 0.7 μm ² or more
The numbers per m ² are also shown in Table 1.

[0019]

[Table 1] Table 1 Dropout (min ^-1 ) Number of foreign matter (cm ^-2 ) Example 1 3 0.03 Example 2 5 0.05 Comparative Example 1 84 0.55

As is clear from the above results, it can be understood that the magnetic tape produced by the method of the present invention has very few dropouts and the cleaning treatment before vapor deposition is very effective.

[0021]

As described above, according to the method of the present invention, foreign matter existing on the magnetic recording layer forming surface of the synthetic resin substrate is removed before the magnetic recording layer is formed. The resulting defects in the magnetic recording layer are greatly reduced, and dropout can be effectively suppressed.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a cleaning device used in a first embodiment.

FIG. 2 is a schematic configuration diagram of a cleaning device used in a second embodiment.

[Explanation of symbols]

 1 Sapphire knife blade 2 Non-woven fabric 3 PET film 4 # 2000 wrapping tape

Claims (2)

[Claims] 1. A method of manufacturing a magnetic recording medium comprising forming a metal thin film magnetic recording layer on a synthetic resin substrate, wherein at least the magnetic recording layer of the synthetic resin substrate is formed before the magnetic recording layer is formed. A method of manufacturing a magnetic recording medium, characterized in that foreign matter on the surface on which the magnetic field is formed is removed by a knife blade or a wrapping tape. 2. The method of manufacturing a magnetic recording medium according to claim 1, wherein the synthetic resin substrate is polyethylene terephthalate (PET).