JPS6050717A - Metallic thin film magnetic tape - Google Patents

Abstract

PURPOSE:To maintain the short wavelength record preservation characteristics of a magnetic tape even through it is preserved for a long period in a wide range of temperatures of low and high levels, by providing a magnetic recording layer made of a ferromagnetic metallic thin film on a single side of a polymer substrate together with a soft magnetic layer formed on the other side of the substrate. CONSTITUTION:A magnetic recording layer 6 is formed with a ferromagnetic metallic thin film on a polymer substrate 5, and a protecting layer 7 is formed on the layer 6. At the same time, a soft magnetic layer 8 is formed on the other side of the substrate 5. Thus a metallic thin film magnetic tape is obtained. The layer 7 has about 100Angstrom thickness at most in order to reduce the spacing loss with the short wavelength recording, and the average roughness of the layer 6 is set at about <=100Angstrom . As a result, both layers 6 and 8 are set adjacent to each other in a range of about 200Angstrom -1,000Angstrom and therefore a leakage magnetic flux given from the layer 6 by a record pattern is closed by the layer 8. This increases the energy stability and improves the demagnetization when the magnetic tape is preserved.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a metal thin film type magnetic tape having a magnetic recording layer made of a ferromagnetic metal thin film suitable for short wavelength recording.

Conventional Structures and Problems In recent years, metal thin film magnetic tapes having a ferromagnetic metal thin film as a magnetic recording layer have attracted attention as a medium with excellent short wavelength recording characteristics. When recorded and reproduced using a video tape recorder (hereinafter referred to as V, T, or R) using a rotating magnetic head, this thin metal film magnetic tape can provide image quality approximately six times higher than the recording density of conventional coated media. It has been reported that the above-mentioned conventional metal thin film magnetic tape will be described below with reference to the drawings.

FIG. 1 shows a cross-sectional view of a conventional metal thin film type magnetic tape, in which a magnetic tape consisting of a ferromagnetic metal thin film is deposited directly on a polymer substrate 1 or via a non-magnetic layer or a soft magnetic layer (not shown). A recording layer 2 is disposed, a protective layer 3 is disposed thereon, and a back coating layer 4 for improving running properties is disposed on the other side of the polymer substrate 1.

However, in the above configuration, the present inventors have developed a Co-Ni-0 based obliquely deposited film, a Co-Ni-0
When a video signal was recorded on an r-based perpendicular magnetization film and its long-term storage characteristics were investigated, it was found that the playback output decreased more than expected.

Possible causes of this are (a) magnetic recording layer 2
(2) Since the tape is made of metal, it corrodes and the flux decreases. (b) Since it is stored by winding it as a magnetic tape, some of the constituent materials or decomposition products are transferred from the back coating layer 4, resulting in space loss. 3', -zo (c) Both (a) and (b) above occurred at the same time.

However, when we predicted the above (a) to (-9) and examined them one by one, it became clear that the same output could be obtained if we recorded again, so it became clear that none of the above (b) and 09 did not apply. This problem must be considered as demagnetization.This demagnetization is thought to be caused by the magnetic poles at one or both ends of the permanent magnet, which is the unit of magnetization, being open, and improvements are desired. ing.

OBJECTS OF THE INVENTION It is an object of the present invention to provide a metal thin film type magnetic tape with improved short wavelength recording storage characteristics.

Structure of the Invention The metal thin film magnetic tape of the present invention has a structure in which a magnetic recording layer made of a ferromagnetic metal thin film is arranged on one side of a polymer substrate and a soft magnetic layer is arranged on the other side, and the recorded state When the magnetic recording layer is wound with the soft magnetic layer, the recorded recording layer and the soft magnetic layer are adjacent to each other, and the leakage magnetic flux generated by the recording pattern from the magnetic recording layer is closed by the soft magnetic layer, making it stable even during long-term storage. JP-A-Sho GO-50717 (2) The amount of recorded magnetization can be maintained.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 2 shows a sectional view of a metal thin film magnetic tape according to an embodiment of the present invention. In FIG. 2, reference numeral 6 denotes a polymer substrate, on which a magnetic recording layer 6 made of a ferromagnetic metal thin film is arranged, a protective layer 7 is arranged on top of the magnetic recording layer 6, and a protective layer 7 is arranged on the polymer substrate 5-A.
A soft magnetic layer 8 is disposed on the other side to constitute a metal thin film type magnetic tape.

As other configurations, it is naturally possible to arrange a non-magnetic underlayer or a soft magnetic underlayer between the magnetic recording layer 6 and the polymer substrate 6, or to arrange a protective layer on the soft magnetic layer 8, but this is not the case. The effects of the invention can be represented by the configuration shown in FIG.

When the metal thin film magnetic tape of the present invention is used in a magnetic recording/reproducing device, for example, V, T, )t, the recorded magnetic tape is stored in a cassette. At this time, the surface of the magnetic recording layer 6 side indicated by arrows A and A' in FIG. 2 and the surface of the soft magnetic layer 8 face each other.

The protective layer 7 is constructed with a thickness of about 100 Å at most in order to reduce spacing loss during short wavelength recording, and the surface of the magnetic recording layer 6 is also smooth with an average roughness of 100 Å or less. When the tape is wound, the magnetic recording layer 6 and the soft magnetic layer 8 are adjacent to each other within a range of 208 to 000, and the leakage magnetic flux generated by the recording pattern from the magnetic recording layer 6 is absorbed by the soft magnetic layer. 8 and is energetically stable, making it possible to improve demagnetization during storage.

Furthermore, it has been experimentally confirmed that demagnetization during storage can be reduced by using an electret polymer substrate 5 of the metal thin film magnetic tape constructed according to the present invention, but this mechanism is not clear. The effect of the present invention is the material and thickness of the polymer substrate 6.

The soft magnetic layer may be designed in accordance with the material, manufacturing conditions, thickness, coercive force, and saturation magnetic flux density of the magnetic recording layer 6, regardless of mechanical properties and the like.

The saturation magnetic flux density of the magnetic recording layer 6 is Bs [Gauss].

The thickness is δ [l1m], and the coercive force is Hc [Oersted].

The saturation magnetic flux density of the soft magnetic layer 8 is B s ' (Gauss),
If the thickness is δ [μtnl] and the coercive force is Hc' [Oersted], BTP・δ′/Bs・δ is selected to be 1 or more, preferably 2 or more, and Hc/Hc is 60 or more, preferably 100 or more. good effects can be obtained.

The polymer substrate 5 used in the present invention is polyethylene-7
L/phthalate, polyethylene naphthalate.

A non-magnetic underlayer is formed on a polyamide, polyimide, polycarbonate, etc. or polymer substrate.

Either a soft magnetic underlayer is provided or the polymer substrate 6 is made into an electret.

There is no particular limitation on the manufacturing method of the non-magnetic underlayer and the soft magnetic underlayer, and the well-known electronic vino vapor deposition method can be used.

A sputtering method, an ion blating method, a wet plating method, a wet coating method, etc. are used as appropriate.

In addition, the means for converting the polymer substrate 6 into an electret and the timing of converting the polymer substrate 6 into an electret are appropriately selected.
In carrying out the present invention, injection of a high-energy electron beam into a polymer substrate can exhibit the most excellent effect.

The material of the ferromagnetic metal thin film forming the magnetic recording layer 6 used in the present invention is Co, Co-Ni, Co-Cr.
.

Co-8i, Co-MO, Co-W, Co-Ti
, Co-V, Co-Ce, Co-Ru, Co-N
i-0, Go-Cr-0, Co-Mo-0, Co-
These include Ni-Cr, Co-Mn-Mg, etc.

A method for obtaining a ferromagnetic metal thin film of the above-mentioned material can be appropriately selected from vacuum evaporation, sputtering, ion blating, wet plating, and the like.

The soft magnetic layer 8 that can be used in the present invention is N i -F
e, Ni-Ti-Fe, Ni-Mn-Ei,
Even with Co-Ni-○ such as Ni-Fe-0, a soft magnetic layer having the effects of the present invention can be obtained by devising manufacturing conditions.

The method for manufacturing the soft magnetic layer 8 can be selected from methods similar to those for manufacturing ferromagnetic metal thin films.

JP-A-Sho GO-50717 (3) Whether the formation of the ferromagnetic metal thin film and the formation of the soft magnetic layer 8 are carried out consecutively or as separate steps can be determined by those skilled in the art after consideration including economic considerations. It is selected.

It is of course possible to arrange a protective layer on the soft magnetic layer 8 in order to improve the practical reliability of the magnetic tape of the present invention, and the type of material, thickness, manufacturing method, etc. of the protective layer can be determined by those skilled in the art. It is something that can be implemented within the scope of knowledge.

Embodiments of the present invention will be described in more detail below with reference to the drawings.

FIG. 3 is a diagram showing the main part of a winding vapor deposition apparatus used to obtain the metal thin film type magnetic tape having the structure shown in FIG. In FIG. 3, a polymeric substrate 9 is configured to undergo deposition as it moves along a rotating support, where the rotating support is comprised of rotating cooling rollers 10° 11 and an endless metal belt 12. , the endless belt 12 is driven to rotate at a constant speed in the direction indicated by the arrow.

Further, the inclination of the endless belt 12 can be configured to be adjustable, and desired magnetic characteristics can be obtained by adjusting the position of the mask 13 or by adjusting the incident angle of the vapor flow. Obtainable.

Note that the polymer substrate 9 is arranged to move from the feed shaft 14 to the winding shaft 15 along the endless belt 12. facing the polymer substrate 9;

An alloy evaporation source for generating the vapor flow is provided, and a high frequency coil 16 for ion brating is provided between the two. The evaporation source container 17 of the alloy evaporation source is a two-tank type and is charged with the A element 18 and the B element 19, and the A element 18 and the B element 19 can be separately impact-heated by electron beams from the electron guns 20 and 21. It is configured like this.

Note that the A element 18 and the B element 19 are not necessarily a single element, but may be an alloy composed of elements with similar vapor pressures. Of course, the amount of evaporation of the He element and the B element may be adjusted by the following.

These systems are arranged inside a vacuum chamber 22, and the inside of the vacuum chamber 22 is evacuated by an exhaust system 23, and gas is introduced from a gas introduction system (not shown) as necessary. It is configured so that it can be done. 24 is a high frequency power supply, and 26 is an insulation introduction terminal.

[Example-1] In the apparatus shown in Fig. 3, A element 18 is Cr and B element 19 is C
A Co--Cr film with a thickness of 0.2/1 m was obtained by high-frequency ion blasting on a polyethylene terephthalate with a thickness of 1 ol and 1 m as a polymer substrate 9. High-frequency power was input at 650 W, and the deposition rate was 800 people/sec for CO and 206 people/sec for Cr.

The Co-Cr film is a perpendicularly magnetized film with a perpendicular coercive force of 1Q60 [Oersted].

The polymer substrate 9 that had been subjected to the above treatment using the apparatus shown in FIG. 3 was reattached to the delivery shaft 14 so that a soft magnetic layer could be formed on the other surface of the polyethylene terephthalate as the polymer substrate 9.

In the apparatus shown in Figure 3, A element 18 is replaced with Ni and B element 19 is replaced with F.
Ni is 880 people/5 (5) with the vapor deposition rate as e.

Ni with Fe content of 210%/% and thickness of 0.3 μm
A -Fe film was obtained.

11゛~゛The coercive force of this Ni-Fe film was 0.6 [Oersted].

The saturation magnetic flux density Bs of the Co-Cr film is 3000 [Gauss], and the saturation magnetic flux density of the Ni-Fe film is 6800 [Gauss].
To form the Co-Cr film, the inside of the vacuum chamber was heated to 1×1σ in advance.
After exhausting to 6 Torr, Ar was introduced and 7X10-
”This was done by ion blating with Torr, but the formation of the Ni-Fe film was performed using a 1×1 vacuum chamber in advance.
After exhausting to σ'Torr, oxygen was introduced to 8 x 10
-” As a result of 0-electron spectroscopy and X-ray electron spectroscopy of the Ni-Fe film deposited with an electron beam at Torr, it was found that the Ni-Fe film was composed of columnar crystals, and Fe was segregated on the surface of the columnar crystals, forming a protective film of Fe3O4 film. .

Tape A is a product of the present invention in which a Co-Cr ferromagnetic layer and a Ni-Fe soft magnetic layer are respectively arranged on both sides of polyethylene terephthalate as a polymer substrate 9 and cut into a width of 8 mm. , a 300 ppm myristic acid solution dissolved in methyl ethyl ketone was applied on the Ni-Fe layer to a thickness of 10 μm, and the dried product was used as Tape B. Tape C had no Fe layer and had only a Co--Cr layer, and Tape D had the Co--Cr layer coated with the same amount of the above-mentioned myristic acid solution.

[Example-2] A polyamide substrate (thickness: 8 μm) was used as the polymer substrate 9,
Xe ion bombardment treatment (Xe ion current density 10 lt A/crtt,
Element 19 was an alloy of CO80% and Ni2O% (7), and the deposition rate was 200 people/n for Or and 700 people/n for CoNi to obtain a Co-Ni-Cr film with a thickness of 0.18 μm.

This Co-Ni-Cr film is an in-plane magnetized film with an in-plane coercive force of 1200 (Oersted) and a saturation magnetic flux density B8 of 3.
It was 400 [Gauss].

The degree of vacuum during vapor deposition was IE 1.5 x 10-5 (excluding oxygen).
Tory, ].

Water pressure a x 1o-6 (Torr, ), hydrogen partial pressure 7 x
1σ6 [Tart), nitrogen partial pressure 5 x 10-' (
To'rr), including other residual gas components a, s x
It was 1o-5 [Torr].

Page 13 Next, it was reinstalled into the apparatus shown in FIG. 3 so that it could be deposited on the other side of the polyamide substrate as the polymer substrate 9.
A soft magnetic layer was formed.

In the apparatus shown in Fig. 3, the element 18 is Mn and the element B 19 is Ni.
- Fe (Ni80%) and Mn deposition rate is 360%
A Mn-Ni-Fe film having a thickness of 0.317 zm was obtained by setting the Ni-Fe film to 1,100 m/sec and 1,100 m/sec.

The coercive force of this Mn-Ni-Fe film is 0.3 [Oerstende] and the saturation magnetic flux density Bs is 6000 [Gauss].
Met.

The degree of vacuum during the formation of the Mn-Ni-Fe film was 2.5
10 [Torr] and oxygen partial pressure up to 1.8X
It was controlled at a partial pressure of 10 [:Torr,].

As a result of electron spectroscopy and X-ray electron spectroscopy, Mn-Ni
-The Fe film is formed from columnar crystals, and the surface of the columnar crystals is M
It was found that about 120 mixed layers of nO2 and Fe5o4 films were formed, and the ratio of MnO2 and Fe3O4 was 2:3 in terms of the elemental ratio of Mn and Fe.

Tape E is a tape with a width of 8 mm that is simply vapor-deposited on both sides.
A solution of lead stearate IIF dissolved in toluene was applied to the surface of the Co-Ni-Cr layer and the Mn-Ni-Fe layer to a thickness of 10 pm and dried to form tape F.
As a comparative example, a tape with only one Co-NiC layer but without an Mn-Ni-Fe layer was used as tape G, which was the same (M
Co-Ni without forming n-Ni-Fe layer
Tape H was prepared by applying the same amount of the above zinc stearate solution onto the -Cr layer.

On the eight types of tapes from Tape A to Tape H described above, saturation recording was performed at a recording wavelength of 0.66 μm using a Sendust head with a gap length of 0.3 μm.

This record level was confirmed immediately after recording. That is, 0.3μm
Based on the head output when playing with a ferrite head with a gap of 1, the playback output after storage for one month in a specific environment was compared relative to each other.

The results are expressed in decibels and summarized in the table below.

The following margin is 16 pages. As is clear from the table above, the product of the present invention can stably maintain the recording level when stored as a wound tape, and this effect becomes even more pronounced when the recording wavelength is further shortened. For example, when recording 0.4 μm on tape B and comparing the storage environment in the three environments mentioned above, the recording level remained at the initial value, whereas on tape D, the recording level was 6C60%.
RH, the output after one month had decreased by edB.

Special WU Mouth HGO-50717 (5) Compared to other configurations, the product of the present invention has good storage stability in terms of output as described above, and is less likely to change because the cupping is a thin metal film on both sides. It also has features such as no abnormal increase in dropouts due to repeated use.

In particular, this effect is thought to be due to the fact that the thin film was formed in an oxygen atmosphere, so the crystal surface of the columnar structure was coated with oxide, making it hard and less susceptible to environmental influences.

As another example, tape prototypes similar to those in Example-1 and Example-2 were manufactured with each polymer substrate heated at 3°KeV and 12μA.
/ctA was made into an electret by electron injection and compared.

The storage characteristics of the electret polymer substrate were examined in detail, and the storage characteristics were further improved.

That is, when tape A and tape 8, in which the polymer substrate was made into electret under the above conditions, were stored at 6oC and 60% RH for 3 months, the playback output of tape A decreased by about 1 dB, but with electret 17. The component of the present invention using a page-sorted polymer substrate maintained its initial playback output.

Although this effect can be obtained with good reproducibility, there are still many aspects that are not clearly understood as to how the space charge distribution within the polymer substrate after being made into an electret affects the preservation of the magnetized state. Therefore, it is currently under consideration.

Note that the effects of the present invention have been confirmed even when the storage period is short.

Effects of the Invention According to the metal thin film magnetic tape of the present invention, as described above,
Since the magnetic recording layer made of a ferromagnetic metal thin film is arranged on one side of the polymer substrate and the soft magnetic layer is arranged on the other side, the recorded recording layer can be wound up in the recorded state. Since the magnetic layer and the soft magnetic layer are adjacent to each other, the leakage magnetic flux of the permanent magnet, which is the recording unit, is efficiently closed by the soft magnetic layer. This has the effect of stably maintaining the amount of recorded magnetization even when the magnetic field is used.

18' This effect becomes larger as the wavelength becomes shorter, so it is slightly improved even in applications where it is erased and used repeatedly, but it is not reliable in the field of magnetic recording where higher density recording is desired for long-term storage. It has great industrial potential as it can ensure safety.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a conventional metal thin film magnetic tape, FIG. 2 is a sectional view of a metal thin film magnetic tape according to an embodiment of the present invention, and FIG. 3 is a sectional view of the metal thin film magnetic tape obtained in FIG. 2. FIG. 2 is a configuration diagram of main parts of a winding vapor deposition apparatus used in the above. 5...Polymer substrate, 6...Magnetic recording layer, 8...Soft magnetic layer. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 2 Figure 3

Claims (1)

[Claims] A metal thin film type magnetic tape characterized in that a magnetic recording layer made of a ferromagnetic metal thin film is arranged on one side of a polymer substrate, and a soft magnetic layer is arranged on the other side.