JPH0944832A - Magnetic recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magnetic recording medium having good characteristics suitable for high-density recording and having a high output from a low range to high range by forming a lower magnetic film in such a manner that columns in the lower magnetic film are grown oblique to the base to show a curved line which is convex over the straight line connecting the starting point and the end point of the column. SOLUTION: For example, a PET film 3 is travelled in the direction (A) in the figure at 2.0m/min velocity, while electron beams are emitted from 10-KW electron gun 8 to heat, melt and vaporize a magnetic metal (Co) in a crucible 4 to form a lower magnetic film 11a to 700Åthickness on the PET film 3 when the film is in the position on a cooling can roll 1. The columns in the magnetic film 11a are grown oblique to the base and show a curved line which is convex from the straight line connecting the starting point and the ending point of the column (with the angle θ1 =30 deg.). During the lower magnetic film 11a is formed, oxygen gas is supplied by 50 sccm rate in the direction from the upstream side to the downstream side from an oxygen gas supply nozzle 7.

Description

Detailed Description of the Invention

[0001]

[0001] The present invention relates to a magnetic recording medium.

[0002]

In recent years, so-called vapor-deposited tapes are considered promising as magnetic tapes for high recording density. In particular, multilayer vapor-deposited tapes are regarded as promising. From this viewpoint, various multilayer vapor deposition tapes have been proposed. However, conventional multilayer vapor deposition tapes have poor frequency characteristics and have problems with durability.

By the way, no one has noticed that the columnar structure of the vapor-deposited magnetic film has a great influence on the frequency characteristics and durability of the multilayer vapor-deposited tape. That is, no consideration has been given to the column structure regarding frequency characteristics and durability. In this regard, as a result of intensive research conducted by the present inventor, a column of the upper magnetic film in the laminated magnetic film has an obliquely grown column having a curve protruding below the straight line connecting the starting point and the ending point. If the column of the lower magnetic film is an obliquely grown column having a curve protruding above the straight line connecting the starting point and the ending point, it may have good frequency characteristics and excellent durability. I understand.

The present invention has been achieved based on such knowledge, and an object of the present invention is to provide a magnetic recording medium excellent in frequency characteristics and durability.

[0005]

An object of the present invention is to provide a magnetic recording medium in which a plurality of thin metal film type magnetic films, in which columns are obliquely grown, are laminated on a support, and columns of lower magnetic film are provided. Is an obliquely grown column having a curve protruding above the straight line connecting the starting point and the end point, and the column of the upper magnetic film is an obliquely curved line protruding below the straight line connecting the starting point and the end point. It is achieved by a magnetic recording medium which is a grown column and in which the column growth direction of the lower magnetic film and the column growth direction of the upper magnetic film are symmetrical.

The starting point and the ending point of the column of the lower magnetic film are
Inclination angle θ of the connecting line₁Is 20 to 60 °, preferably 30
~ 50 ° (or 120-160 °, preferably 130)
~ 150 °) is preferable, and the starting point of the column of the upper magnetic film
Inclination angle θ of the straight line connecting the end point ₂120-170 °, hope
130-150 ° (or 30-80 °, preferably
40 to 60 °) is preferable.

The "symmetry direction" in the "direction in which the growth direction of the column of the lower magnetic film and the growth direction of the column of the upper magnetic film are symmetric" does not mean only complete symmetry, but the growth direction of the column. Means that the growth direction of the column of the lower magnetic film is, for example, 0 to 90 °, and the growth direction of the column of the upper magnetic film is 90, for example.
It means something in the direction of ~ 180 °.

Further, in a magnetic recording medium in which a plurality of metal thin film type magnetic films in which columns are obliquely grown are laminated on a support, the lower magnetic film is formed by a low incidence angle nucleation method. This is achieved by a magnetic recording medium characterized in that an upper magnetic film is formed in the reverse direction by a high incidence angle nucleation method.

The reason why the magnetic recording medium configured as described above has good durability is considered as follows. First, when forming the lower magnetic film to be deposited on the support, magnetic particles having higher energy are deposited and deposited toward the lower side. Therefore,
High binding strength to the support. Therefore, the magnetic film is firmly bonded to the support, is hard to peel off, and is highly durable.

The reason why the frequency characteristics of the magnetic recording medium configured as described above are good (high output even in a high frequency region) is considered as follows. With the structure of the above magnetic film, the coercive force of the upper magnetic film is large, whereas the coercive force of the lower magnetic film is small, resulting in less thickness loss and high output even in the high frequency region. Further, since the column growth direction of the lower magnetic film and the column growth direction of the upper magnetic film are configured to be symmetrical, high output can be obtained even when used in both forward and reverse directions such as an audio tape. can get.

It is preferable that the upper magnetic film is thicker than the lower magnetic film. Further, when comparing the oxygen content on the upper side with the oxygen content on the lower side, the upper magnetic film has a higher oxygen content on the upper side, and the lower magnetic film has the oxygen content on the upper side and the oxygen content on the lower side. When compared with the content, it is preferable that the lower oxygen content is high.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention is a magnetic recording medium in which a plurality of metal thin film type magnetic films in which columns are grown obliquely are laminated on a support, and the columns of the lower magnetic film are the starting point and the ending point. Is a diagonally grown column having a curve protruding above the straight line connecting to and the upper magnetic film column is a diagonally grown column having a curve protruding below the straight line connecting the starting point and the end point. In addition, the column growth direction of the lower magnetic film and the column growth direction of the upper magnetic film are symmetrical.

A magnetic recording medium in which a plurality of metal thin film type magnetic films in which columns are grown obliquely are laminated on a support, and the lower magnetic film is formed by a low incidence angle nucleation method, The upper magnetic film is formed in the opposite direction by the high incidence angle nucleus generation method. The inclination angle θ _{1 of the} straight line connecting the starting point and the ending point of the column of the lower magnetic film is 20 to 60 ° (or 120 to 160 °), and the inclination angle of the straight line connecting the starting point and the ending point of the column of the upper magnetic film. θ ₂ is 120 to 170 ° (or 30 to 80 °).

The magnetic recording medium of the present invention having the above characteristics can be obtained as follows. First, the oblique vapor deposition apparatus of FIG. 1 is prepared. In FIG. 1, 1 is a cooling can roll, 2a is a supply side roll of the support body 3, 2b is a winding side roll of the support body 3, and the support body 3 is a cooling can roll 1 from the supply side roll 2a via a guide roller. To the take-up side roll 2
It is wound up in b. The support 3 may be either magnetic or non-magnetic, but is generally non-magnetic.
For such a support 3, an organic material such as polyester such as PET, polyamide, polyimide, polysulfone, polycarbonate, olefin resin such as polypropylene, cellulose resin, vinyl chloride resin is mainly used. An undercoat layer for improving the adhesion with the magnetic film is appropriately provided on the surface of the support. Particles of the magnetic material 5 from the crucible 4 are generated in the traveling path of the support 3 wound from the supply side roll 2a through the cooling can roll 1 to the winding side roll 2b, that is, when traveling along the cooling can roll 1. Flying and adhering
accumulate. Examples of the material of the magnetic particles forming the metal magnetic film include Co—N in addition to metals such as Fe, Co, and Ni.
i alloy, Co-Pt alloy, Co-Ni-Pt alloy, Fe
-Co alloy, Fe-Ni alloy, Fe-Co-Ni alloy,
Fe-Co-B alloy, Co-Ni-Fe-B alloy, Co
-Cr alloy, or those that contain a metal such as Al, as well as nitride _{(Fe 4 N, Fe 8 N} , Fe-
N) or carbide (Fe ₃ C ₅ ) and their composites are used. 6 is a shielding plate, 7 is an oxygen gas supply nozzle, 8 is an electron gun, and 9 is a vacuum chamber.

Using the oblique vapor deposition apparatus having the above-described structure, first, the support 3 travels in the direction of arrow A along a predetermined travel path in the vacuum chamber 9 (from the supply side roll 2a in the state shown in FIG. 1 to the cooling can roll 1). (Running so as to be wound up on the winding side roll 2b) and the inside of the vacuum chamber 9 is set to 10 ⁻⁴ to
Evacuate to a degree of vacuum of about 10 ⁻⁶ Torr. Then, the magnetic metal 5 in the crucible 4 is melted and vaporized by heating the electron beam from the electron gun 8, and the thickness of the magnetic metal 5 on the support 3 is reduced by the low incidence angle nucleus generation method (LIN method) at the position of the cooling can roll 1. At 400 to 1500 Å, as shown in FIG. 2, the lower magnetic film 11a of the column grown obliquely having a curved line protruding above the straight line connecting the starting point and the ending point (the inclination of the straight line θ ₁ = 20 to 60 °) is formed. To do.

After the lower magnetic film 11a is formed and wound on the winding-side roll 2b, this time it travels in the direction B opposite to the direction A (from the winding-side roll 2b in the state shown in FIG. 1). It runs so as to be wound around the supply-side roll 2a via the cooling can roll 1), and at the position of the cooling can roll 1 on the lower magnetic film 11a on the support 3 by the high incidence angle nucleus generation method (HIN method). Is 800-3000Å, and Fig. 2
As shown in, the straight line connecting the starting point and the ending point (the slope of the straight line θ ₂
= 120 to 170 °), the upper magnetic film 11b of the obliquely grown column having a curve protruding downward is formed.

When forming the lower magnetic film 11a,
Since the oxygen gas is made to flow from the upstream side to the downstream side, the lower magnetic film 11a has a higher oxygen content toward the lower side. On the other hand, when forming the upper magnetic film 11b, oxygen gas is flown from the downstream side, so that the upper magnetic film 11b is formed.
Has a higher oxygen content toward the top. LIN as above
50 to 50 made of diamond-like carbon, boron carbide, silicon nitride, or the like, if necessary, on the magnetic film in which the method magnetic film (lower magnetic film 11a) and the HIN method magnetic film (upper magnetic film 11b) are sequentially stacked. A protective film having a thickness of about 200Å is provided. Further, a fluorine-based lubricant such as perfluoropolyether is provided with a thickness of about 20 to 70Å.

[0018]

Example 1 The magnetic recording medium of this example is obtained by the oblique vapor deposition apparatus shown in FIG. That is, the non-magnetic support (6 μm-thick PET film) 3 is attached to the supply-side roll 2
It is passed from a through the cooling can roll 1 so as to be guided to the winding side roll 2b, and the inside of the vacuum chamber 9 is set to 10 ⁻⁴ to 10 ⁻⁶ T.
Evacuate to a vacuum degree of about orr. And 2.0 m / m
PET film 3 running in the direction A in FIG. 1 at a speed of in
In contrast, the electron beam heating from the electron gun 8 of 10 kW melts and evaporates the magnetic metal (Co) in the crucible 4, and PET is formed at the position of the cooling can roll 1 by the LIN method.
A lower magnetic film of a column which is 700 Å thick and has a thickness of 700 Å on the film 3 and which has a curved line protruding above a straight line (inclination θ ₁ = 30 ° of the straight line) connecting the starting point and the ending point. 11a is formed. When forming the lower magnetic film 11a, 50 sccm from the oxygen gas supply nozzle 7
Oxygen gas is supplied from the upstream side to the downstream side at a ratio of.

After the lower magnetic film 11a is formed, the PET film 3 on which the lower magnetic film 11a is formed has a thickness of 2.0.
The magnetic can (Co) in the crucible 4 is melted and vaporized by traveling in the reverse direction (B direction in FIG. 1) at a speed of m / min by electron beam heating from the electron gun 8 of 15 kW, and the cooling can roll 1 At the position, the thickness is 1200Å on the lower magnetic film 11a by the HIN method, and as shown in FIG. 2, it has a curve protruding below the straight line (the inclination of the straight line θ ₂ = 135 °) connecting the starting point and the ending point. The upper magnetic film 11b of the obliquely grown column is formed. This upper magnetic film 11b
70 scc from the oxygen gas supply nozzle 7 when forming
Oxygen gas is supplied from the downstream side at a rate of m.

As described above, the LIN method magnetic film (lower magnetic film 11a) and the HIN method magnetic film (upper magnetic film 11b).
After forming the film, a diamond-like carbon film is formed to a thickness of 50Å by ECR plasma CVD method, and then a fluorine-based lubricant such as perfluoropolyether (trade name F
OMBLIN AM 2001) was formed to a thickness of 20Å.
Further, an Al vapor deposition film (back coat film) having a thickness of 0.2 μm was provided on the surface of the PET film 1 opposite to the surface on which the magnetic film was formed, and cut into a predetermined width to produce a magnetic tape.

[0021]

Second Embodiment In the first embodiment, the traveling speed of the PET film 3 when forming the lower magnetic film 11a is 1.5 m / min, the output of the electron gun 8 is 12 kW, the oxygen gas supply amount from the oxygen gas supply nozzle 7 is 70 sccm, When the upper magnetic film 11b was formed, the traveling speed of the PET film 3 was 2.0 m / min, the output of the electron gun 8 was 15 kW, the oxygen gas supply amount from the oxygen gas supply nozzle 7 was 70 sccm, and θ ₁ = 50 °, 1500
Å Thick lower magnetic film 11a, at θ ₂ = 140 °, 1000
A magnetic tape was produced in the same manner as in Example 1 except that the upper magnetic film 11b having a thickness of Å was formed.

[0022]

Third Embodiment In the first embodiment, the traveling speed of the PET film 3 when forming the lower magnetic film 11a is 2.5 m / min, the output of the electron gun 8 is 10 kW, the oxygen gas supply amount from the oxygen gas supply nozzle 7 is 45 sccm, When the upper magnetic film 11b was formed, the traveling speed of the PET film 3 was 2.0 m / min, the output of the electron gun 8 was 15 kW, the oxygen gas supply amount from the oxygen gas supply nozzle 7 was 60 sccm, and θ ₁ = 20 °, 550 Å
Thickness lower magnetic film 11a, θ ₂ = 150 °, 1200Å
A magnetic tape was produced in the same manner as in Example 1 except that the thick upper magnetic film 11b was formed.

[0023]

Fourth Embodiment In the first embodiment, the traveling speed of the PET film 3 during film formation of the lower magnetic film 11a is 2.5 m / min, the output of the electron gun 8 is 12 kW, the oxygen gas supply amount from the oxygen gas supply nozzle 7 is 50 sccm, At the time of forming the upper magnetic film 11b, the traveling speed of the PET film 3 was 2.0 m / min, the output of the electron gun 8 was 16 kW, the oxygen gas supply amount from the oxygen gas supply nozzle 7 was 70 sccm, and θ ₁ = 135 °, 650
Å Lower magnetic film 11a, θ ₂ = 40 °, 1200 Å
A magnetic tape was produced in the same manner as in Example 1 except that the thick upper magnetic film 11b was formed.

[0024]

Comparative Example 1 In Example 1, the running direction of the PET film 3 when forming the lower magnetic film 11a and the upper magnetic film 11b was set to the opposite direction. In this comparative example, after the lower magnetic film 11a is formed, the lower magnetic film 11a is loaded on the supply side to form the lower magnetic film 11a and the upper magnetic film 11b.
The traveling directions of the T film 3 are the same, and θ ₁ = 5
At 0 °, the lower magnetic film 11a having a thickness of 1200 Å, θ ₂ = 50
A magnetic tape was prepared by performing the same procedure as in Example 1 except that the upper magnetic film 11b having a thickness of 1200 Å was formed.

[0025]

[Characteristics] Magnetic characteristics (coercive force Hc, saturation magnetic flux density Bs, Br / Bs), surface roughness R of the magnetic tapes obtained in the above examples.
A, output characteristics (outputs at 1 MHz, 5 MHz, and 10 MHz) and still durability (output reduction after repeated running for 3 hours) were examined, and the results are shown in Table-1.

Table-1 Hc (Oe) Bs (G) Br / Bs Ra (nm) Output characteristics (dB) Still durability 1MHz 5MHz 10MHz (dB) Example 1 1550 6400 0.84 1.9 +0.9 +1.0 +1.2 -0.4 Example 2 1530 6600 0.78 2.1 +1.1 +0.6 +0.4 -0.2 Example 3 1490 6900 0.80 1.8 +1.4 +0.6 +0.8 -0.8 Example 4 1520 6400 0.83 2.4 +0.7 +0.7 +0.9 -1.1 Comparative Example 1 1540 6400 0.83 2.4 0 0 0 -1.9 * The output characteristics are relative values based on Comparative Example 1. As can be seen, the present invention has excellent still durability and high output from low to high ranges. Is obtained and is suitable for high density recording.

[0027]

[Effect] High output from low range to high range, suitable for high-density recording, and highly durable.

[Brief description of drawings]

FIG. 1 is a schematic view of an oblique vapor deposition apparatus for manufacturing a magnetic recording medium of the present invention.

FIG. 2 is a schematic diagram of a magnetic recording medium of the present invention.

[Explanation of symbols]

 3 Support 11a LIN method magnetic film (lower magnetic film) 11b HIN method magnetic film (upper magnetic film)

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Junko Ishikawa 2606 Akabane, Kai-cho, Haga-gun, Tochigi Prefecture Kao Corporation Company Information Science Laboratory

Claims (4)

[Claims] 1. A magnetic recording medium in which a column has a plurality of metal thin film type magnetic films laminated obliquely on a support, and the column of the lower magnetic film is above a straight line connecting a starting point and an ending point. The column of the upper magnetic film is a column grown obliquely, and the column of the upper magnetic film is a column grown obliquely with the curve protruding below the straight line connecting the starting point and the end point, and the lower magnetic film The magnetic recording medium is characterized in that the column growth direction and the column growth direction of the upper magnetic film are symmetrical. 2. A magnetic recording medium in which a plurality of metal thin film type magnetic films in which columns are grown obliquely are laminated on a support, and the lower magnetic film is formed by a low incidence angle nucleation method. A magnetic recording medium, wherein an upper magnetic film is formed in a reverse direction by a high incidence angle nucleus generation method. 3. The magnetic recording medium according to claim 1, wherein the upper magnetic film is thicker than the lower magnetic film. 4. The upper magnetic film has a large oxygen content on the upper side when the oxygen content on the upper side is compared with the oxygen content on the lower side, and the lower magnetic film has a lower oxygen content than the oxygen content on the upper side. The magnetic recording medium according to claim 1, wherein the oxygen content on the lower side is higher when compared with the oxygen content on the lower side.