JPH06301972A - High-molecular film and manufacture of magnetic recording medium - Google Patents

Abstract

PURPOSE:To obtain a magnetic recording medium having an excellent electromagnetic conversion characteristic, durability, and reliability by forming recessed and projecting sections on the front and rear surfaces of a high-molecular film to prescribed depths. CONSTITUTION:After setting a substrate 1 having a flat surface on the take-up shaft 3 of a vacuum device 2, the substrate 1 is wound around a take-up shaft 5 through a plasma treatment device 4 and recessed and projecting sections having depths of 30-350Angstrom are formed on the front and rear surfaces of the substrate 1 by electric discharge machining. When a ferromagnetic metallic film is formed on the surface of the high-molecular film thus obtained by using a vacuum evaporation device, a magnetic recording medium having an excellent electromagnetic conversion characteristic, high durability, and long still life can be obtained due to shape effects produced on the front and rear surfaces of the high-molecular.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a polymer film and a magnetic recording medium used in the fields of video equipment and information equipment.

[0002]

2. Description of the Related Art In recent years, magnetic recording media have made remarkable technological advances, as seen in the improvement of magnetic recording density. As examples of conventional magnetic recording media, iron oxide powder, chromium oxide powder, pure iron powder and the like used in audio and video tape materials are used as abrasives and binders of resins and the like.
There is a coating type magnetic recording medium which is coated on a polymer film together with.

However, the holding force is higher than that of the conventional coating type tape.
In order to improve recording density electromagnetic conversion characteristics, Fe by vacuum deposition method, ion plating, sputtering method, etc.
Studies have been made on a metal thin film type magnetic recording medium in which a magnetic metal such as Ni, Co or Cr is vapor-deposited on a polymer film alone or as an alloy. Also, for audio by the oblique deposition method,
Metal thin film magnetic recording media for video have already been put to practical use. Further, as a magnetic recording medium for hard disk used as a memory of a computer, a method of depositing a cobalt-based oxide on an aluminum or glass substrate by a sputtering method is used.

Further, in these memory media, there is an increasing demand for improvement in recording density and image quality. On the other hand, improvement in reliability and running stability, which are weak points of the metal thin film type magnetic recording medium, are expected.

Conventionally, as a polymer film used for a metal thin film magnetic recording medium, a flat polymer film having a surface with an average particle size of 200Å is used as a method for producing a metal thin film magnetic recording medium. The production method of vapor-depositing a magnetic metal on a polymer film as shown in (FIG. 4) with a vacuum vapor deposition machine is superior to other methods as a method of producing a thin film magnetic recording medium. It is influential. Here, a conventional vapor deposition tape manufacturing method and a vacuum vapor deposition machine will be described. A polymer film 9 having inorganic particles and the like formed thereon is set on the feed shaft 10 to remove the cooling can 1.
After 2 passes, it is wound by the winding shaft 13. The magnetic metal in the ceramic crucible 15 is attached to the electron gun 1 from below the cooling can.
Dissolve and evaporate at 4 to form on polymer film. At this time, the metal vapor flow unnecessary for vapor deposition is masked by the shield plates 16 and 17. Normal evaporation tape (ME) is 40 degrees to 9
The vapor deposition angle component of 0 degree is used.

[0006]

In the case of a magnetic recording medium, downsizing and high image quality are required for video tapes, and high recording density is required for information equipment. It is important to improve running durability and still life as well as characteristics and electromagnetic conversion characteristics.

However, although the electromagnetic conversion characteristics can be improved by making the surface property of the conventional film substrate fine and reducing the loss factor due to the spacing, durability running and still life are shortened, and conversely when the surface property is rough, the running property becomes poor. Although it can be improved, there was a problem in electromagnetic conversion characteristics.

Therefore, an object of the present invention is to solve the above-mentioned drawbacks and to provide a magnetic recording medium having excellent electromagnetic conversion characteristics, high durability and high reliability.

[0009]

In order to solve this problem, the present invention provides a polymer film having this shape provided with irregularities of 30 Å or more and 350 Å or less by subjecting the surface of the polymer film to electric discharge machining or electrification treatment. A ferromagnetic metal layer is formed on the top by a vacuum deposition method to manufacture a magnetic recording medium.

[0010]

[Function] A polymer film having a flat surface is subjected to electric discharge machining such as plasma, glow, arc or the like, or electrification treatment such as electron gun, ion gun, microwave gun and the like to give an uneven shape of 30 Å or more and 350 Å or less. For example, by performing electrical discharge machining on the surface of a polymer film, a random geometric pattern is generated on the film surface, which has a shape of about 150Å in the depth direction. Further, in the surface treatment by the electrification treatment, a pattern on a straight line in the running direction of the film is generated at a depth of about 200Å. The magnetic tape on which a magnetic metal thin film is formed on this polymer film by vacuum deposition can produce a magnetic recording medium with long durability and still life without impairing electromagnetic conversion characteristics due to the shape effect generated on the film surface. .

[0011]

EXAMPLES Examples of the present invention will be described in detail below.

(Embodiment 1) As shown in FIG. 1, a flat polyethylene terephthalate (PET) film 1 is set on an unwinding shaft 3 of a vacuum device 2 and wound on a winding shaft 5 via a plasma processing device 4. take. The plasma processing apparatus has a structure in which Ar gas is introduced through the inlet port 6 and the treated gas is exhausted through the exhaust port 7, and the electrodes 8 are provided on the front and back surfaces and are confined by a magnet using high frequency. The degree of vacuum in the vacuum device is ^10-4 To
rr, 0.1 Torr in the plasma processing apparatus, and 0.
A voltage of 350V is applied at 2A.

(Embodiment 2) (FIG. 2) is a schematic view of a vapor deposition apparatus for subjecting a PET film surface to plasma treatment similarly to Embodiment 1 and continuously depositing a magnetic metal thin film on the surface. The PET film 9 is set on the unwinding shaft 10, sent through the plasma processing device 11 to the rotating drum 12, and wound up by the winding shaft 13. At this time, the magnetic metal in the ceramic crucible 15 is melted by the electron beam 14 from below the rotating drum, and deposited on the film. A mask 16 cuts off a metal vapor flow unnecessary for vapor deposition. Further, the shielding plate 17 prevents the metal vapor flow from flowing into unnecessary portions during vapor deposition.

A polyethylene terephthalate substrate having a thickness of 10 μm was used as the polymer film substrate, and the magnetic layer had a total thickness of 2000Å. At this time, the average film deposition rate from the electron beam evaporation source was 3000 nm / sec, the vapor deposition incident angle was 40 ° to 90 °, and the rotary drum temperature during vapor deposition was 0 °. The plasma treatment condition is 0.1 as in the first embodiment.
Performed at Torr, 0.5A, 350V.

(Embodiment 3) (FIG. 3) is a schematic view of a vapor deposition apparatus for subjecting the surface of a polyethylene naphthalate (PEN) film to a charging treatment and vapor depositing a magnetic metal thin film on the surface, as in the case of Embodiment 2. Unwinding PET film 9 1
Set to 0, and then through the rotating drum 12, the charging device 18
And is wound up by the winding shaft 13. At this time, the magnetic metal in the ceramic crucible 15 is melted by the electron beam 14 from below the rotating drum, and deposited on the film. A mask 16 cuts off a metal vapor flow unnecessary for vapor deposition. Further, the shielding plate 17 prevents the metal vapor flow from flowing into unnecessary portions during vapor deposition.

A polyethylene naphthalate substrate having a thickness of 7 μm was used as the polymer film substrate, and the magnetic layer had a total thickness of 2000 Å. At this time, the average film deposition rate from the electron beam evaporation source was 3000 nm / sec, and the vapor deposition incident angle was 4
Deposition was carried out at a temperature of 0 to 90 degrees and a rotating drum temperature of 0 degrees at the time of deposition. The charging condition was 0.1 A and 200 V.

Table 1 shows the evaluation results of the electromagnetic conversion characteristics, running durability test, and still life of the 8 mm deck.

[0018]

[Table 1]

The performance and effect of the metal thin film type magnetic recording medium according to the above embodiment will be described. The evaluation method of the metal thin film type magnetic recording medium was 8 mm tape after vapor deposition and was 8 m on the market.
The m-video deck was modified into an evaluation device, and the electromagnetic conversion characteristics were investigated using a metal head. The electromagnetic conversion characteristics were evaluated by the output near the recording frequency 7 MHZ and C / N, and compared as a relative output with respect to the conventional example. In addition, we improved the commercially available 8mm VCR to compare the running durability of repeated,
Damaging on the surface of the tape after repeated running for 500 passes was observed with an optical microscope, and the still life was 40 ° C-10 at high temperature and low humidity.
% Under a special environment, and evaluated with a tape load of 30 gr.

As a result, the C / N of the electromagnetic conversion characteristic is higher than the conventional example by 1.5 dB or more. The output of the deck after repeated 500 passes was stable, and the damage on the tape surface was evaluated by microscopic observation. As a result, all of the examples of the present invention were excellent in less tape damage than the conventional examples. The evaluation results of the still life were excellent in all the examples of the present invention as in the durability running test.

In carrying out the present invention, the polymer film is made of polyamide, polyimide, other than polyethylene terephthalate and polyethylene naphthalate of the present invention.
Other films such as polyvinyl chloride and polycarbonate can also be used. The plasma processing method and the charging processing method are not limited to the present invention, and other methods are possible.

In addition, when a magnetic recording medium is manufactured by the vacuum deposition method using the polymer film of the present invention, magnetic metal, incident angle during deposition, deposition temperature, deposition film thickness, introduction of oxygen gas, etc. However, other methods are possible without being limited to the manufacturing method of the present invention. Needless to say, the present invention can be applied not only to magnetic recording media but also to liquid crystal alignment films and other various functional thin films.

The size and pattern of the shape given in carrying out the present invention are related to the applied voltage and the current. If the plasma discharge treatment is too strong, the depth of the groove is deep and the shape is fine and the running performance can be improved, but the electromagnetic conversion is performed. The characteristics deteriorate. Similarly in the charging process, as the applied voltage and the current increase, the depth of the groove becomes deeper and the number of grooves in the traveling direction becomes smaller. Also in this case, the size and shape of the shape are important as in the case of the plasma treatment. Particularly, the depth of the groove is preferably in the range of 30Å to 350Å, and particularly 50Å to 200Å is optimum.

[0024]

As described above, according to the method of manufacturing a magnetic recording medium of the present invention, it is possible to obtain a magnetic recording medium excellent in electromagnetic conversion characteristics, running durability and reliability.

Further, the magnetic recording can be continuously processed in the vacuum layer during the production of the magnetic recording by the vacuum evaporation method, and the complicated process as in the prior art is not required.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a plasma discharge processing apparatus showing a first embodiment of the present invention.

FIG. 2 is a schematic view showing a method of manufacturing a magnetic recording medium of Example 2 of the present invention.

FIG. 3 is a schematic diagram showing an apparatus for manufacturing a magnetic recording medium of Example 3 of the present invention.

FIG. 4 is a schematic diagram showing a conventional magnetic recording medium manufacturing apparatus.

[Explanation of symbols]

 1 Polymer Film 2 Vacuum Device 3 Unwinding Shaft 4 Plasma Processing Device 5 Winding Shaft 6 Gas Inlet 7 Gas Exhaust 8 Electrode 9 Polymer Film 10 Unwinding Shaft 11 Plasma Processing Device 12 Rotating Drum 13 Winding Shaft 14 Electronic Gun 15 Crucible 16 Mask 17 Shield 18 Charging device

Claims (4)

[Claims] 1. A method for producing a polymer film, characterized in that unevenness of 30Å to 350Å is formed on the front and back surfaces of a substrate having a flat surface by electric discharge machining. 2. A method for producing a polymer film, characterized in that unevenness of 30 Å to 350 Å is formed on the front and back surfaces of a substrate having a flat surface by a charging process. 3. A method of manufacturing a magnetic recording medium, comprising the step of subjecting the polymer film of claim 1 to electrical discharge machining with a vacuum evaporator and then depositing a ferromagnetic metal. 4. A method for producing a magnetic recording medium, comprising the steps of: charging a polymer film on a polymer film according to claim 1 with a vacuum vapor deposition machine and then depositing a ferromagnetic metal.