JPH0799572B2 - Magnetic recording medium - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a magnetic recording medium having a ferromagnetic metal thin film suitable for high density magnetic recording as a magnetic recording layer.

2. Description of the Related Art In recent years, the recording density of the technology for recording and reproducing audio and images by the helical scanning method using a rotary magnetic head has been increasing among magnetic recording media. Therefore, in order to further shorten the wavelength in the future, a magnetic recording medium with a new structure is required.On a non-magnetic substrate such as a polymer film, a perpendicular magnetization film obtained by a Co-Cr sputtering method or a Co-Ni film is used. -O
Vapor-deposited tape with a diagonal vapor-deposited film is promising [for example, IEEE TRANSACTIONS ON MAGNE
TICS) vol MAG-21, NO-3, PP1217-1220 (1985)]. FIG. 2 is an enlarged cross-sectional view of an example of the vapor deposition tape. In the figure, reference numeral 1 is a polymer film such as polyethylene terephthalate film, which also has an undercoat layer for providing irregularities as needed. 2 is an electron beam evaporation method,
0.05μm or 0.3 formed by high frequency sputtering method
A magnetic recording layer made of a ferromagnetic metal thin film having a thickness of about .mu.m is a protective lubricating layer 3, which can be appropriately selected and used from among many proposals such as lamination of an amorphous carbon film and fluorine oil. Reference numeral 4 denotes a back coat layer, which is a coating layer made of a resin containing a filler, a lubricant, etc. to assist the running property [Japanese Patent Publication No. 56-23208, Japanese Patent Laid-Open No. 58-4
1418, JP 61-151835, JP 61-1871
22).

In addition, the magnetic tape is also characterized in that the volume recording density can be increased, and the trend of thinning the tape is also important as a means for long-term recording. From this viewpoint, the vapor-deposited tape is advantageous for thinning and can be developed. The current situation is that it is being advanced.

Certainly, the magnetic recording layer is about 1/10 thinner than the conventional coating type magnetic layer, and the Young's modulus of the magnetic recording layer is 10 times or more larger, so it is thought that all layers can be made thin, but Aiming at practical use in the temperature range, a disadvantageous surface having a bimetal structure becomes conspicuous. Therefore, a tape structure having vapor-deposited layers on both surfaces has been proposed [JP-A-61-1103].
43, etc.].

FIG. 3 is an example of an enlarged cross-sectional view of a double-sided vapor deposition type magnetic tape. In FIG. 3, reference numeral 5 is a polymer film, and a polyethylene terephthalate film or the like having earthworm-shaped irregularities on both sides is used. 6 is a magnetic recording layer composed of a ferromagnetic metal thin film such as a perpendicular magnetization film or an obliquely evaporated film, and 7 is composed of a ferromagnetic metal thin film in the case of a double-sided access type, and SiO, SiO _{2 in} the case of a single-sided access. , a non-magnetic thin film such as Al ₂ O _3, MgF _2, reactive deposition, is intended to be formed by a method such as RF sputtering 8 is a protective lubricating film.

Problems to be Solved by the Invention However, although the double-sided evaporation type magnetic tape as described above can reduce the temperature change in the cupping state, it has a sufficient signal-to-noise (hereinafter referred to as S / N) ratio at the time of recording and reproducing at a short wavelength. There was a problem that I could not get. The reason is that if the surface on the side opposite to the magnetic recording layer is too rough, the S / N will decrease due to shape transfer, and if the surface is made finer, running will become unstable and tracking will not be sufficiently performed at high density recording. Therefore, the balance between S / N and running stability has not been fully achieved, and improvements have been desired.

The present invention has been made in view of the above circumstances, and provides a double-sided vapor deposition type magnetic recording medium that achieves both S / N and running stability.

Means for Solving the Problems In order to solve the above-mentioned problems, the magnetic recording medium of the present invention comprises a fine particle coating layer, a ferromagnetic metal thin film, and a lubricating layer laminated on one surface of a polymer film, On the other side of the molecular film, a vapor deposition layer having protrusions having an oligomer as a nucleus is arranged.

The magnetic recording medium of the present invention has the above-mentioned structure, and since the protrusion having the oligomer as the nucleus is formed after the magnetic recording layer is formed, the shape transfer does not occur, and the protrusion having the oligomer as the nucleus causes the contact area. Since it can be made smaller, friction with the running system is reduced and running stability is also obtained.

Examples Hereinafter, one example of the magnetic recording medium of the present invention will be described with reference to the drawings.

FIG. 1 is an enlarged cross-sectional view of a magnetic recording medium according to an embodiment of the present invention. In the figure, 9 is a polymer film such as polyethylene terephthalate, polyethylene naphthalate, polyphenylene sulfide, polyamide imide and polyimide, and 10 is fine particle coating. In the layer, fine particles of Al ₂ O ₃ , BaSO ₄ , CaCO ₃ , SiO ₂ , TiO _{2 and the} like are fixed on the polymer film 9 with a resin. 11 is Co-Ni, Co-Cu, Co-Fe, Fe-Ag, Co-Cr, Co-Ge,
Co-Hf, Co-La, Co-Mg, Co-Mo, Co-Nb, Co-O, Co-Os, Co
-P, Co-Ru, Co-Sm, Co-Ta, Co-Ti, Co-V, Co-W, Co-Ni
-O, Co-Cr-Nb, Co-Ni-Pr, etc. ferromagnetic metal thin film, supported by electron beam evaporation method, sputtering method, etc. It was formed while moving along the body. This ferromagnetic metal thin film has good contact between the rotating support and the smooth polymer film, so it is cooled well and there is no degassing from the polymer film, the magnetic properties are microscopically uniform and the noise is improved. It has been done. 12 is a lubricant such as fatty acid, fatty acid amide, perfluoro carboxylic acid, and fluorine-substituted fatty acid. If necessary, a carbon film or a SiO ₂ sputtered film may be used together with the lubricant. 13 is an oligomer, which is deposited from the polymer film when the vapor deposition layer 14 is formed, resulting in the formation of granular protrusions on the vapor deposition layer.
This provides driving stability. Of course, a lubricating layer can be arranged on this, but the amount of transfer can be covered by winding it as a tape, and it may be selected appropriately.

The protrusions formed by the oligomer do not already cause shape transfer to the ferromagnetic metal thin film, so the S / N does not decrease.

Hereinafter, examples will be described more specifically in comparison with comparative examples.

On a polyethylene terephthalate film with a thickness of 7.3 μm, 10 particles of SiO ₂ fine particles with a diameter of 100 Å are used with gum arabic
(Μm) ^{2 A} fixed fine particle coating layer is arranged, and a smooth surface of the polyethylene terephthalate (roughness, 23Å) film is placed on a cylindrical can having a diameter of 50 cm, and the cylindrical can is kept at 10 ° C. Diagonal vapor deposition with an incident angle in the range of 90 degrees to 44 degrees at a minimum was performed in 3.3 × 10 ^-5 (Torr) oxygen under Co-Ni.
-Pr [Co: Ni: Pr = 75: 15: 10 (wt%)] was vaporized by 0.12 μm electron beam heating.

Next, a SiO film was formed to a thickness of 0.1 μm on the polyethylene terephthalate surface having a roughness of 23 Å by a high frequency sputtering method. At this time, an oligomer was made to come out by passing a 95 ° C heating medium through a cylindrical can having a diameter of 50 cm.

The average frequency of oligomers was 10 ⁷ / cm ² , and the maximum height was 500Å.

Next, perfluorooctanoic acid is added to the Co-Ni-Pr-O side at 80Å
It was vacuum deposited. This was used as a magnetic tape having a width of 8 mm.

In the comparative example, a film having a thickness of 7.2 μm, in which the same fine particle coating layer as that in the example is arranged on one side and a water-soluble polymer earthworm-like ridge layer on the other side, was used as a trial. Earthworm-like ridge layer has a maximum roughness of 550Å
And two types of 200Å were used.

Using this film, under the same conditions as in the example, Co-Ni-
Pr was electron beam evaporated in oxygen. Next, the cylindrical can was set to 0 ° C. to form an SiO film of 0.12 μm, and perfluorooctanoic acid was vacuum-deposited on the side of 80Å, Co—Ni—Pr—O to obtain a magnetic tape of 8 mm width.

Various evaluations were performed by using Tape A as an example and Comparative Example as a tape B having an earthworm-like raised layer having a roughness of 550Å and a tape C having a roughness of 200Å. Recording wavelength of 0.6μm,
When the reproduction S / N was measured, Example tape A was O (dB)
Then, tape B is -1.9 (dB), tape C is -0.7
In the example (dB), the noise was improved. 40 ° C 85% RH
When repeatedly recorded and played back on tape A, the 100th playback S / N was +1.0 (dB) compared to the initial value, but tape B was -0.2 (dB) compared to the initial value. However, since there is a difference in the initial value from the tape A, there is a difference of about 3 (dB) even under this condition, and the tape C has an advantage of -2.2 (dB) with respect to the initial value.

EFFECTS OF THE INVENTION According to the present invention, both the S / N and running stability of a double-sided vapor deposition type tape are improved, so that there is an excellent effect that a magnetic tape having a thin thickness suitable for high density recording can be realized.

[Brief description of drawings]

FIG. 1 is an enlarged sectional view of a magnetic recording medium according to an embodiment of the present invention, and FIGS. 2 and 3 are enlarged sectional views of a conventional magnetic recording medium. 9 ... Polymer film, 10 ... Fine particle coating layer, 11 ... Ferromagnetic metal thin film, 12 ... Lubrication layer, 13 ... Oligomer, 14 ...
… Deposition layer.

Claims (1)

[Claims] 1. A fine particle coating layer, a ferromagnetic metal thin film, and a lubricating layer are laminated on one surface of a polymer film, and a vapor deposition layer having protrusions with an oligomer as a nucleus is arranged on the other surface of the polymer film. A magnetic recording medium characterized by the above.