JP2594380B2 - Magnetic recording media - Google Patents

Description

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

2. Description of the Related Art Efforts to increase the recording density have been continuously made to reduce the size and improve the performance of recording / reproducing devices. Recently, it has been expected that a ferromagnetic metal thin film will be put to practical use as a magnetic recording layer. [IEEE TRANS-ACTIONS ON MAGNETICS Vo
l.MAG-21, No. 3, pp 1217-1220 (1985)]. Although many combinations of ferromagnetic metal thin films are conceivable as materials, few of them have shown a practical possibility, and a perpendicular magnetization film of Co-Cr or the like [Japanese Patent Publication No. 58-91, Japanese Unexamined Patent Publication No. 61-120331] and obliquely deposited films or wet-plated films of Co-Ni, Co-Ni-O, etc. [JP-B-41-19389, JP-A-53-42010]
For these reasons, the development of a protective lubricating layer has recently been mainly focused on for practical use. At present, a ferromagnetic metal thin film is placed directly on a polymer film such as a polyethylene terephthalate film or a polymer film by applying an undercoat such as fine particles, and then an electron beam evaporation method or a sputtering method is applied. A method in which a solution in which a lubricant such as ether is dissolved is applied and dried [JP-A-57-179948]
JP-A-61-178718], disposing of lubrication via an oxide film [JP-A-61-151830], and a combination of a carbon film and a fluorocarbon system [JP-A-61-178718]. 1425
No. 25 gazette] and the like, and although the carbon film is still thick in a magnetic disk, it is partially put to practical use, and studies have been made on carbonaceous materials, and the usefulness of increasing the hardness [US Pat.
No. 622] is also known.

However, when high-density recording is advanced with a ferromagnetic metal thin film formed on a particle-coated surface, and especially when narrow-track recording is performed, the amount of crosstalk increases and a single on-track state can be obtained. There is a problem that a pure high C / N cannot be obtained with the actual machine, and improvement has been desired.

The present invention has been made in view of the above circumstances, and provides a magnetic recording medium with improved narrow track C / N in a magnetic recording layer exhibiting durable granularity.

Means for Solving the Problems In order to solve the above-mentioned problems, the magnetic recording medium of the present invention is characterized in that the particle diameter of the columnar fine particles constituting the magnetic recording layer is smaller than the particle diameter of the smooth part, Is within the range of 1.5 to 3 times.

Effect The magnetic recording medium of the present invention can substantially secure the microscopic uniformity of the magnetic characteristics and improve the C / N even if the track is narrowed by the above-described configuration.

Embodiment Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is an enlarged sectional view of a main part of the present invention. In the figure, 1 is polyethylene terephthalate, polyethylene-2,
6-naphthalate, polyphenylene sulfide, polyether ether ketone, polyether safone, polyimide, aramid and other polymer films, 2 is SiO ₂ , TiO ₂
Fine particles such as ₂ , Al ₂ O ₃ , Eu ₂ O ₃ , SnO ₂ , Cr ₂ O ₃ , WO _{3 and the} like, and 3 is a fixing resin such as polyester, polyurethane, polysulfone and the like.

The fine particles 2 are used in the range of 80 ° to 300 °, and the density is preferably in the range of 5 / μ ^{2 to} 100 / μ ² .

4 and 5 are columnar fine particles constituting the magnetic recording layer, 4 is columnar fine particles A grown on a smooth portion, and 5 is the fine particles 2 described above.
Columnar fine particles B grown under the influence of the above. 4 and 5 have a preferable range in the particle diameter, and the particle diameter of 4 is d ₁ , 5
When d ₁ / d ₂ is from 1.5 to 3, where d is the particle size of d ₂ , this is required from the viewpoint of high density recording performance as described later. Here the definition of particle size high-resolution scanning electron microscope, corresponding to the diameter of when fixing the columnar fine particle structure with high energy transmission electron microscope or the like, at a position of 0.1 t ₀ from the surface when the film thickness was set to t ₀ It shall be.

By satisfying the above-mentioned relationship within the range of 30 ° to 200 ° in the particle diameter defined in this way, the effect of the present invention can be sufficiently obtained.

The control of d ₂ / d ₁ is based on Co, Co-Ni, Co-Cr, Co-T
a, It can be performed by making the mobility of the vapor-deposited atoms such as Co-Mo equal to or close to that of the smooth portion. As an example of a method therefor, Al having a large oxygen trapping effect is vapor-deposited on a polymer film with a calculated film thickness of about 5 to 20 ° within a high incident angle range of 90 ° to 70 °, Co, Co-Ni, etc. in oxygen
There is a method of vapor deposition at 000 ° / sec or more, preferably 5000 ° / sec. In addition, a can that supports the polymer film
It can also be controlled by cooling to 30 to -40C.

In addition to the above components, the protective lubricating layer is made of a combination of plasma polymerized film, oxide film, carbon film, aliphatic alcohol, perfluorocarboxylic acid, perfluoropolyether, etc. in consideration of spacing loss. 50 ~ 20
What is necessary is just to select the structure which can obtain excellent durability reliability at 0 °.
If necessary, a back coat layer is also provided.

Hereinafter, more specific examples of the present invention will be described in comparison with comparative examples.

On a smooth polyethylene terephthalate film with a thickness of 10 μm and an average roughness of 20 mm and a maximum roughness of 40 mm without any intrinsic particles, ultracentrifugal SiO ₂ fine particles of 150 mm in diameter are fixed with 20 / μ ² polyester resin, 0.08 (Tor
r) With an oxygen partial pressure of [initial exhaust 3 × 10 ^-5 (Torr)], 15
After performing glow discharge treatment at (kHz) 600 (W) for 2 seconds, Al was electron-beam evaporated.

On top of that, along the cylindrical can with a diameter of 1 m, the minimum incident angle, the amount of introduced oxygen, and the can temperature were set to 10 ゜ to 58 ゜, 0.11 respectively.
~ 1.3 (/ min), change in the range of -35 ℃ ～ + 30 ℃, C
O-Ni (Ni: 20 wt%) was subjected to 0.17 μm electron beam evaporation to change the particle system to form a magnetic recording layer. Some of the comparative examples
The conventional method was used without Al treatment. After forming each magnetic recording layer,
Approximately 40 perfluoropolyether linoleyl on its surface
ÅApply, and on the other side, a back coat layer obtained by applying and drying a coating liquid of the same composition with a mixed filler (1: 1) of 0.4 μm polyester, CaCoO ₃ , and carbon, and disposing an 8 mm wide Magnetic tape was used.

Each of them was modified from an 8mm video, and the narrow track C / N was evaluated. In addition, still durability was evaluated at any 10 points. Table 1 summarizes the constituent requirements and characteristics of the magnetic recording medium.

As can be seen from Table 1, if d ₂ / d ₁ is 1.5 or less, the durability of the still becomes weak, and if d ₂ / d ₁ is 3.0 or more, the characteristics deteriorate in a narrow track C / N. It can be said that it is preferable.

 Next, an example of a Co-O perpendicular magnetization film will be described.

9 μm thick aramid film (average roughness 25 mm, maximum roughness 35 mm) with Co-Fe fine particles (fine particle diameter 100 mm, CoiF
e = 45: 55at%) was placed a 30-month / μ ^2. The fixing resin was polyamide and was 20 mm in uniform film thickness. Ar0.09 (To surface
rr) Sputter etching was performed at 13.56 (MHz) and 1 (kW) to expose the Co-Fe surface and widen the particle size control range.

50cm diameter cylindrical can (can temperature -10 ℃ ~ + 150
(° C.), Co was electron-beam evaporated at an incident angle of 35 ° to 12 ° to form a 0.2 μm Co—O perpendicular magnetization film.
Oxygen gas was introduced from the nozzle at the tip of the mask that limited the incident angle to 12 degrees, and He gas was introduced from the nozzle at the tip of the mask that limited the incident angle to 35 degrees, to adjust the columnar particle diameter. Co
-O film is coated with perfluoropolyether stearylamide at about 50 °, and a 0.4 μm back coat layer is provided.
Processed into a millimeter wide tape. The comparative example is a 120 mm diameter Cr ₂
O ₃ fine particles were applied at a rate of 25 / μ ^2, and a film produced under the same conditions as in the example except that a Co—O film was formed without sputter etching was used.

Each tape is pit length 0.17μm, track pitch 10μ
Table 2 shows the results of the relative comparison of C / N between m and 5 μm.

In addition to the above-described embodiments, the same effect can be obtained with a two-layer structure of a Co-Cr (Cr20 wt%) perpendicular magnetization film formed by a sputtering method and a Co-O obliquely deposited film formed by an electron beam evaporation method. It was confirmed.

Advantageous Effects of the Invention As described above, according to the present invention, excellent C / N can be obtained even in high-density recording by narrowing the track, and durability is maintained in a practical range.

[Brief description of the drawings]

FIG. 1 is an enlarged sectional view of a main part of a magnetic recording medium according to one embodiment of the present invention. 1 ... polymer film, 2 ... fine particles, 4 ... columnar fine particles A, 5 ... columnar fine particles B

 ──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Hiroaki Tateno 1006 Kadoma, Kadoma, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd. (56) References JP-A-59-157833 (JP, A)

Claims (1)

(57) [Claims] 1. The method according to claim 1, wherein the particle diameter of the columnar fine particles constituting the magnetic recording layer is 1.5 to 1.5 times the particle diameter of the smooth part.
A magnetic recording medium having a range of three times.