JPH03116517A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To obtain a magnetic recording medium having excellent durability and corrosion resistance at high production speed by incorporating nitrogen by 0.3 - 2atm.% into an iron film formed by oblique deposition on a polymer film. CONSTITUTION:Nitrogen is incorporated by 0.3 - 2atm.% into an iron film 2 formed by oblique deposition on a polymer film 1. For example, when iron vapor is deposited by an electron beam deposition method on a traveling polymer film 1 with changing the minimum incident angle of the beam from right angle, nitrogen atoms are made to irradiate the film at the same time, or nitrogen gas is introduced to incorporate nitrogen into the film. By this method, crystallinity of iron can be improved and defects are reduced in the obtd. film, which improves long-term stability and characteristics as the magnetic recording layer. Particularly, the recording layer is suitable for high production speed since the process needs no reaction.

Description

[Detailed description of the invention] Industrial applications The present invention relates to a magnetic recording medium suitable for high-density recording.

2. Description of the Related Art In general, magnetic recording media with a ferromagnetic metal thin film as a magnetic recording layer are produced by depositing an alloy based on Fe, Co, Ni, etc. on a polymer film such as polyethylene terephthalate by electron beam evaporation or sputtering. It is well known that it improves high-density recording characteristics by adhering to
In addition to durability under sliding loads, it is difficult to say that the so-called corrosion resistance, which deteriorates in characteristics over time depending on environmental conditions, is sufficient, and improvements are being made. One of these is the use of an iron nitride-based thin film as a magnetic recording layer (Japanese Unexamined Patent Publication No. 60-2
Publication No. 36113, Japanese Patent Application Publication No. 184927/1983,
JP-A-1-105331). This thin film contains 70% iron
A combination of diagonal incidence at a high incidence angle of over 100 degrees and nitrogen ion irradiation produces a coercive force of 100.

(Os) or more, and the film has excellent stability over time [IEEE Transactions on Magnetics]
on Magnetics) vo 1, MA
G-23, &-5, P, P, 2833-2635 (1
987)].

Problems to be Solved by the Invention However, the thin film described above has a thin film formation rate of 1oO(
The deposition film thickness is 1ooO
A human-sized membrane is required, and productivity remains an issue. The present invention aims to provide a magnetic recording medium that takes advantage of the high magnetic flux density characteristics of iron-based materials with durability and corrosion resistance close to those of iron nitride-based materials, and that can be obtained at high speed. This is the purpose.

Means for Solving the Problems In order to solve the above-mentioned problems, the magnetic recording medium of the present invention has an obliquely deposited film disposed on a polymer film with a thickness of 0.3 to 2at.
% of nitrogen.

Function: The magnetic recording medium of the present invention has the above-described structure, and is a film with improved iron crystallinity and reduced defects, which has improved stability over time and characteristics as a magnetic recording layer, and does not require any particular reaction. This means that it can be achieved by high-speed film formation.

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(Example 1) FIG. 1 is an enlarged sectional view of a magnetic recording medium according to an example of the present invention. In Figure 1, 1 is polyethylene terephthalate, polyethylene naphthalate, polyphenylene sulfide,
A polymer film such as polyether ether ketone or the like may be used, which has been given a shape with a fine particle coating layer, a mountain range coating layer, etc., if necessary. 2 is an obliquely deposited iron film,
The film contains 0.3 to 2 at% nitrogen. Oblique deposition involves depositing 90% on a polymeric film moving along a rotating support.
Iron is deposited by electron beam evaporation while the minimum incident angle (θi) is changed at an angle of incidence, and at the same time, nitrogen atoms are irradiated or nitrogen gas is introduced. The deposition rate using the electron beam evaporation method is in the range of 1ooO (in/on) to 9000 (8μ), the incident angle is optimized according to the required coercive force, and the degree of vacuum is 1 × 1O-5 (Torr). It is preferable to carry out the following. 3 is a protective lubricating layer, and 4 is a back coat layer. The protective lubricant layer is made of plasma polymerized film, carbon film, fatty acid, perfluoropolyether, etc., which are optimized to balance spacing loss and protective effect.

It is presumed that the inclusion of nitrogen in the iron film improves the crystallinity, since the coercive force does not increase, but the squareness improves, and corrosion resistance may also improve due to fewer defects. Although strict proof is difficult, a more specific example will be explained in detail below in comparison with a comparative example.

10 Sio2 microparticles with a diameter of 10 people/(μm) are placed on a polyethylene terephthalate film with a thickness of 12 μm.
The minimum angle of incidence (θ
i) and 30KV1 without irradiating the nitrogen atom beam.
With an electron beam of 00KW (maximum output), 99.99% of the iron in the map was evaporated from the MqQ container, and the
M:, )~9o00 (1800 iron films were deposited in the range of I/Watanabe, and on top of that, 100 hexamethylcyclotrisilazane plasma polymerized films were placed, and a 0.46 μm back coat layer was applied. A magnetic tape with a width of 8 mm was obtained.

8mm video (EV-
8900 Nony ■) was used to compare the output. The tape conditions and evaluation results are summarized in Table 1.

As can be seen from Table 1, the magnetic tape of the present invention also has good corrosion resistance, but the comparative example has poor corrosion resistance. The corrosion resistance obtained has already been reported.

Fe work N carefully manufactured at a low speed of 1oo (input/m)
It is equivalent to the membrane repeμ, and can be said to be extremely useful in terms of high speed. Although the mechanism is not clear, 0.3
If the content exceeds the range of at% to 2 at%, the corrosion resistance will deteriorate, so it is preferable to keep this range.

Table 1 (Example 2) Another means to solve the problem is to deposit iron obliquely on a base layer of Cr, V, Mo, Nb, Ta, or w that is vertically deposited on a polymer film. It is something.

Due to the above-described structure, the magnetic recording medium of the present invention has iron having the same crystal structure as the underlayer, so even though the underlayer is vertically evaporated, the backing factor is increased and corrosion resistance is improved. The crystallinity is improved by epitaxial growth on the underlying crystal, resulting in a magnetic recording medium with low noise.

FIG. 2 is an enlarged sectional view of a magnetic recording medium according to an embodiment of the present invention. In FIG. 2, 5 is vertically deposited Cr.

The base layer is made of any one of V, Mo, Nb, Ta, and W. In vertical deposition, the angle of incidence is preferably within 30 degrees. There are also preferable conditions regarding the degree of vacuum, polymer film temperature, etc., but the degree of vacuum is 5 x 10
-5 (Torr) or less, and the polymer film temperature is preferably 10°C or more. The film thickness is preferably 300 Å or more and 3000 Å or less. 6 is an obliquely deposited iron film, which may be combined with the magnetic recording layer of Example 1, but an improved magnetic recording layer can be obtained even if it does not contain nitrogen due to the effect of the underlayer. The other numbers may have the same structure as in FIG.

Examples of the present invention will now be described in more detail in comparison with comparative examples.

On a polyethylene naphthalate film with a thickness of 10.6 μm, 120 Cr2O3 particles with a diameter of 11 pieces/(μm
) and on top of that Or, V, Mo, Nb, Ta.

Perform vertical evaporation of either W by electron beam evaporation method,
Further, iron (99,999%) was obliquely evaporated, the same plasma polymerized film as in Example 1 was placed thereon, and the same back coat was applied to make an 8 mm tape. Both examples and comparative examples,
Using a high band 8mm deck (EV-8soo),
The results of comparing C/N in LP mode are summarized in Table 2 together with the tape conditions.

It can be seen from Table 2 that the tape of this example has excellent corrosion resistance, good squareness ratio, and improved noise and C/N ratio as shown in Table 2.

(Example 3) Another means to solve the problem is to stack an iron film obliquely deposited on the polymer film 1 and an obliquely deposited iron nitride film whose columnar growth direction is tilted in the opposite direction. Due to the above-described structure, the magnetic recording medium of the present invention has a structure in which the attack of microscopically corrosive gas is weakened by the intermingling of the iron nitride system on the surface side and the columnar fine particles of the obliquely deposited iron film on the lower layer, resulting in stable stability over time. By adopting a two-layer structure, finer magnetic domains can be achieved, noise can be improved, and a high C/N ratio can be achieved.

FIG. 3 is an enlarged sectional view of a magnetic recording medium according to an embodiment of the present invention. In FIG. 3, parts that may have the same configuration as in FIG. 1 are given the same numbers. In Fig. 3, 7 is an obliquely vapor-deposited iron film, and the suitable film thickness is 800 to 160 degrees. The obliquely vapor-deposited iron film 7 is composed of an aggregate of columnar fine particles 8, and assuming that the direction of inclination is as shown schematically, the columnar fine particles 9 constituting the laminated iron-iron nitride-based obliquely vapor-deposited film 9 are Tilting in the opposite direction is a constituent requirement. The film thickness is 300 to 8
00 people is preferred. A thicker one is advantageous from the viewpoint of corrosion resistance, but a thinner one is better when considering productivity, and the above-mentioned numerical value is a compromise range between the two. The iron/iron nitride-based obliquely vapor-deposited film referred to herein includes the solid film described in Example 1, and can also include the conventionally known Fe-N film.

In addition, the underlayer may be arranged based on Example 2, and the obtained properties will be even more preferable, but the manufacturing process will be a little complicated, so the selection,
You just have to deal with it.

Examples of the present invention will now be described in more detail in comparison with comparative examples.

20 Fe2O2gjt particles/(μ
m) 2 arranged, move the film (input direction) along a cylindrical can with a diameter of 1 m and change θi, 3 X 10 = ~
4.5 × 10-6 (Torr) diagonally evaporate iron,
While moving the film in the opposite direction to the input direction (direction B),
By changing θ, a Kaufmann-type nitrogen ion source was applied to the section from 90' to θi, and the temperature was 1°KeV.
, 40 μA/d ion irradiation was performed to form an iron/iron nitride-based obliquely vapor-deposited film, and the same protective film and the same back coat layer as in Example 1 were placed thereon to form an 8 mm tape.

In the comparative example, a comparison was made between lamination in the entry direction and lamination in the entry direction and B direction, but with the second layer also made of iron film. The evaluation was made using the same criteria as in Example 2.

(o(dB) is the same as o(dB) in Table 2.) The tape conditions and evaluation results are summarized in Table 3.

Table 3 shows that the actual flow side is superior to the comparative example in achieving and maintaining high C/N.

Table ' Effects of the Invention As described above, according to the present invention, the corrosion resistance, high output, and low noise of a magnetic recording medium with a magnetic recording layer made of iron-based material with a high saturation magnetic flux density can be realized practically in terms of productivity of the medium. It has an excellent effect that can be achieved at a standard level.

[Brief explanation of drawings]

FIG. 1, FIG. 2, and FIG. 3 are enlarged sectional views of magnetic recording media in each embodiment of the present invention. 1...Polymer film, 2...Iron (0
, 3 to 2 at% nitrogen containing) film, 3... Protective lubricating layer, 6... Base layer (e.g. Cr), 6...
... Obliquely evaporated iron film, 7... Obliquely evaporated iron film, 9.
...Obliquely deposited iron/iron nitride film.

Claims (3)

[Claims] (1) The obliquely deposited iron film placed on the polymer film is 0.3
A magnetic recording medium characterized by containing ~2 at% nitrogen. (2) Cr, V, Mo vertically deposited on polymer film
, Nb, Ta, or W, on which iron is diagonally deposited. (3) A magnetic recording medium comprising a stack of an obliquely deposited iron film disposed on a polymer film and an obliquely deposited iron-iron nitride film whose columnar growth direction is oppositely inclined.