JPS6185626A - Production of magnetic recording medium - Google Patents

Abstract

PURPOSE:To decrease signal drop-out and to prevent the generation of earing or blocking during taking up by taking up a substrate on which a thin ferromagnetic metallic film is formed on a take-up shaft under the take-up tension set at <=3.5kg/mm<2> from a rotary support without using a stripping means. CONSTITUTION:A let-off part 1 is wound spirally with a polyethylene- terephthalate film (f). The film (f) let-off from the part 1 is pressed to a cooling can 3 by a nip roller 2 and is moved along said can where the vapor of the ferromagnetic metal evaporated from an electron beam evaporating source 4 is stuck to said film at the incident rate controlled by a mask 5. The film (f) on which the thin ferromagnetic film is formed is moved along the can 3 by a nip roller 6 and is taken up on a take-up shaft 7. The take-up tension is set at <=3.5kg/mm<2> in this stage. The film which can decrease the signal-drop out is thus formed and the generation of earing and blocking which arise during taking-up is thus prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method for manufacturing a magnetic recording medium, and in particular to a method for winding a plastic film on which a ferromagnetic metal film is formed by vapor deposition or the like. Regarding improvement.

BACKGROUND OF THE INVENTION Magnetic recording media such as magnetic tape and magnetic sheets are widely used in the audio and video fields. For example, a coated type magnetic tape in which ferromagnetic powder is dispersed in a binder is also used, but as the demand for high-density recording has recently increased, the recording density of this coated type is reduced by the binder. Instead, thin-film magnetic recording media, which have a large saturation magnetization and can form a ferromagnetic metal film on a support by direct vapor deposition, sputtering, ion blasting, etc. without the need for a binder, are increasingly being used. It has become.

In order to manufacture a magnetic recording medium having such a ferromagnetic metal film, for example, a plastic film is moved along a cooling can and heated vaporized ferromagnetic metal is deposited to form a ferromagnetic metal film on the film. The film on which the ferromagnetic metal film is formed is then wound onto a winding shaft to enable continuous production.

However, in this manufacturing process, when the tension of the film to be wound around the winding shaft is increased, the winding becomes tighter as the winding diameter increases, and the ferromagnetic metal film is pressed against the back side of the film on the support. The ferromagnetic metal film may be damaged. In addition, since the thickness of the ferromagnetic metal film is thin, the smoothness of the film surface also appears on the entire surface of the film, so a thin and smooth film is used. Because of the unevenness, when the film is wound up, the unevenness on the back side of the film may be transferred to the surface of the ferromagnetic metal film. If the ferromagnetic metal film is scratched or uneven, the signal to be recorded in that area is lost, resulting in a so-called dropout phenomenon. In particular, the higher the frequency of signals recorded on video tapes, the more likely small scratches or irregularities can cause dropouts.

Furthermore, if the winding tension of the film is too high, a so-called ridge phenomenon occurs in which the edges of the wound film rise up, and when this occurs, wrinkles occur in the subsequent wound film.

In addition, if the tension of this film is too large and the length of the film is long, the spinal pressure will increase, so there will be adhesion between the back surface of the film and the ferromagnetic metal film inside the film. Blocking occurs. These are major obstacles to mass production.

In particular, recent trends in magnetic recording technology include, for example, audio tapes are transitioning from compact cassettes to microcassettes, and in the video field, from the current VH3 and β formats to 88
With the transition to milli-video and electronic cameras, both are aiming for further miniaturization and higher density, and as mentioned above, dropouts are more likely to occur due to scratches and unevenness in the ferromagnetic metal film. , it has become even more important to avoid this.

For this reason, conventionally, when manufacturing a type of magnetic tape in which a ferromagnetic metal is vapor-deposited, measures have been taken to prevent the winding tension from increasing. For example, in Japanese Patent Application Laid-open No. 59-24446, a magnetic layer is formed by electron beam evaporation while a film is moved along a rotating support, and then the film is separated from the rotating support by a roller.
A configuration is shown in which the film is wound with a force smaller than this pull-off tension.

However, providing a so-called peeling means that separates the film from the rotating support using rollers complicates the structure of the entire manufacturing system, which adds to the hassle of control and maintenance. I don't like it.

As described above, in the conventional manufacturing method of ferromagnetic metal film type magnetic recording media, after forming a ferromagnetic metal film into a film, the tension for winding the film was too high, so it was difficult to use it as a magnetic recording medium. There are problems such as dropouts, and there are also problems with those provided with a separate peeling means, and improvements have been desired.

OBJECTS OF THE INVENTION The first object of the present invention is to prevent scratches on the ferromagnetic metal film when the magnetic recording medium is manufactured and to prevent unevenness on the back surface of the polymer support. To provide a method for manufacturing a magnetic recording medium that does not cause dropout when used as a magnetic recording medium.

A second object of the present invention is to provide a method for manufacturing a magnetic recording medium that does not cause ear scratching or knocking when the magnetic recording medium is wound.

A third object of the present invention is to provide a method for manufacturing a magnetic recording medium that can achieve the above object without providing a peeling means for peeling the support from the rotating support.

Structure of the Invention In order to achieve the above object, the present invention forms a ferromagnetic metal film as a magnetic layer while moving a support for forming a magnetic layer along a rotating support, and forms a ferromagnetic metal film as a magnetic layer. When the support formed with the above-mentioned structure is wound onto the winding shaft without passing through a peeling means for peeling it off from the rotating support, the winding tension is set to 3.
It is characterized in that it is less than 5g/mrd.

Next, the present invention will be explained in detail.

In the present invention, the winding tension for winding the polymer support on which the ferromagnetic metal film is formed is 3.5 Kg/mrd or less, preferably 2.5 Kg/mrd or less. ! 5Kg/mrrl or less. 3
．． If it exceeds 5 kg/mm, the ferromagnetic metal film may be scratched, or the unevenness on the back side of the polymer support may be transferred to the surface of the ferromagnetic metal film, which may cause dropouts when used as a magnetic recording medium. Become.

Supports used in the magnetic recording medium in the present invention include polyethylene terephthalate, polyethylene-2,
Examples include polyesters such as 6-naphthalate, polyolefins such as polypropylene, cellulose derivatives such as cellulose triacetate and cellulose diacetate, and plastics such as polyamide and polycarbonate, but are not limited to these.

The ferromagnetic metal film formed on the support is Fe,
Metals such as Co, Ni or Fe-Co, Fe-N
i, C.

-Ni, Fe-Co-Ni,, Fe-Rh,,
Fe-Cu, Co-Cu, Co-Au.

Co-Y, Co-La, Co-Pr 5Co-G
d, Co-5III, Co-PL.

Ni-Cu, Mn-B1, Mn-5b,
Mn-AE, Fe-Cr s Ni-Cr 5Fe-C
Examples include, but are not limited to, ferromagnetic alloys such as o-CrSFe-Co-Ni-Cr formed into thin films by vacuum evaporation, ion blasting, sputtering, or the like.

The conditions for forming the ferromagnetic metal film can be easily determined by those skilled in the art, and are, for example, under a vacuum of 1 to 5 x 10 Torr and at a conveying speed of 10 to 100 m/win.

The above-mentioned support provided with a back coat layer can also be used in the method for producing a magnetic recording medium in the present invention. For this back coat layer, commonly used binders, inorganic or organic surface roughening agents, lubricants, antistatic agents, etc. are used.

Note that an intermediate layer may be provided between the bank coat layer and the support to improve adhesion.

Effects of the Invention As described above, the present invention allows a ferromagnetic metal film to be formed along a rotary support without providing a peeling means for peeling the support from the rotary support. m
Since the winding is done with a tension less than rrl, the surface of the ferromagnetic metal film may be scratched during winding, or the unevenness of the polymer support may be imprinted, resulting in dropouts when used as a magnetic recording medium. You can reduce the things that cause this. In addition, the phenomenon of blocking due to raised edges during winding can be reduced. These operations can be carried out without using a special device such as a peeling means, and the apparatus can be simplified and its handling and maintenance can be facilitated.

EXAMPLES Next, the present invention will be described in detail, but the present invention is not limited thereto.

FIG. 1 is a schematic explanatory diagram of the apparatus used in this example. The film f fed out from
is pressed by nip roller 2 and the cooling can 3
Here, the ferromagnetic metal vapor evaporated from the electron beam evaporation source 4 is regulated to enter through the mask 5 and deposited thereon. At this time, Co in an oxygen atmosphere
An alloy of 80% by weight Ni and 20% by weight Ni was evaporated, thereby forming a ferromagnetic metal film with a thickness of 0.1810. Further, the film f on which the ferromagnetic metal film is formed is moved along the cooling can 3 by the nip roller 6 and wound onto the take-up shaft 7. This tension when winding up (
Kg/mrd) was set to 2.5.3.5.4.5.5.5 for each case, and each tape was slit into 1/2 inch width to create a magnetic tape. .

The magnetic tape created by each tension is VHS
Set it in a format cassette and record a 100% white level signal, and when playing it, measure the attenuation of the RAD amplifier output to the video with a dropout of 16 dB and the duration of 5 μsec or more using a dropout counter for 10 minutes.
The average value per minute is shown in the graph of Figure 2. In Figure 2, the vertical axis is the number of dropouts, and the horizontal axis is the winding tension (Kg/mn?) at the time of winding. . From this figure, it can be seen that there is less dropout in the pressure range of 3.5 Kg/m rrf or less.

[Brief explanation of drawings]

Fig. 1 is a schematic explanatory diagram of an apparatus used in an embodiment of the method of the present invention, and Fig. 2 shows the relationship between the tension at the time of manufacturing and the dropout measurement results of a magnetic recording medium produced by the method of the present embodiment. This is a graph showing. In the figure, f is a film, 3 is a rotating support, and 7 is a winding shaft. October 4, 1980 mt map row 4

Claims (2)

[Claims] (1) A ferromagnetic metal film is formed as the magnetic layer while moving the support for forming the magnetic layer along the rotating support, and the support on which the ferromagnetic metal film is formed is removed from the rotating support. A method for manufacturing a magnetic recording medium, characterized in that the winding tension is set to 3.5 Kg/mm^2 or less when the magnetic recording medium is wound onto a winding shaft without passing through a peeling means for peeling. (2) The method for manufacturing a magnetic recording medium according to claim 1, characterized in that the winding tension is 2.5 kg/mm^2 or less.