JPS60243818A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To obtain a magnetic recording medium which decreases variance in crystal orientability and improves S/N at a short wavelength by forming a vertical magnetic recording layer via a specific polymerized film on a polyester film. CONSTITUTION:This magnetic recording medium is formed by disposing a vertically magnetizable film 7 directly or via a soft magnetic layer 6 on the plasma- polymerized film 5 disposed on the polyester film 4 having >=40% degree of crystallinity. The properties of the plasma-polymerized film can be made uniform even if said film is extremely thin; in addition, the variance in the orientability of the soft magnetic layer owing to a difficulty in the control of said orientability is improved by the crystal part and non-crystal part of polyester. Since DELTAtheta50 cam be made small and uniform, noise is decreased and the S/N at the short wavelength is improved. The medium for short wavelength recording with which the noise occurring in the fluctuation of magnetism is decreased and the S/N is improved is thus obtd.

Description

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

Conventional configuration and problems The perpendicular recording method uses a magnetic recording medium with an axis of easy magnetization perpendicular to the running direction of the magnetic recording medium such as a tape or disk, that is, in the thickness direction of the magnetic recording layer. It is configured to magnetize the recording medium in the thickness direction and leave magnetization to remain in this direction.By doing this, the self-demagnetizing field can be made smaller as the wavelength becomes shorter, resulting in higher density. This is something that is attracting attention.

As shown in FIG. 1, the perpendicular magnetic recording medium used in the above perpendicular recording method consists of a soft magnetic layer 2 and a perpendicularly magnetized material such as Co-(r) on a non-magnetic substrate 1 such as a polymer film. A stack of ferromagnetic metal thin films 3 (hereinafter referred to as perpendicular magnetization films) has good recording sensitivity.
This is said to be the most preferable configuration.

However, from the perspective of mass-producing such perpendicular magnetic recording media, such a structure has a drawback that it is not suitable for mass production.

That is, the C-axis orientation, which indicates the crystal anisotropy of the hexagonal Co-1r alloy, which is a measure of the performance of the perpendicularly magnetized film;
This is because the half-value width Δθ60 (degrees) of the rocking curve of the X-ray diffraction line due to the (002) plane is strongly influenced by the soft magnetic layer, so careful control of the crystal growth of the soft magnetic layer is required. .

Therefore, even if a wide and continuous medium with such a configuration is obtained, the variation in Δθ6o is large and the signal-to-noise ratio (S/N
) Since a good perpendicular magnetic recording medium cannot be obtained, an improvement has been desired.

In particular, polyester substrates with the most harmonized physical properties as substrates for magnetic recording media, especially polyester films with a crystallinity of 40% or more, which is preferred from the viewpoint of elongation at break, as substrates for tapes, have variations in △θ5o. The present invention has been made in view of the above circumstances, and provides a perpendicular magnetic recording medium using a highly versatile polyester film as a substrate with an improved S/N ratio. be.

Components of the Invention The magnetic recording medium of the present invention comprises a polyester film having a crystallinity of 40% or more, a plasma polymerized film disposed thereon, and a perpendicular magnetization film directly or via a soft magnetic layer. This is a short wavelength recording medium with improved S/N ratio and improved noise due to magnetic fluctuations.

DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 2 is an enlarged sectional view of the magnetic recording medium of the present invention. In FIG. 2, 4 is a polyester substrate having a crystallinity of 40% or more, 5 is a plasma polymerized film, 6 is a soft magnetic layer, and 7 is a perpendicular magnetization film.

As another example of the structure, the effects of the present invention can basically be obtained even when the soft magnetic layer is not interposed. Of course, it is possible to implement such arrangements without departing from the gist of the present invention.

The substrate used in the present invention is a polyester film such as polyethylene terephthalate or polyethylene naphthalate, with a degree of crystallinity of 40% or more, and a thickness of 4 μm to 20 μm.

The soft magnetic layer that can be used in the present invention includes Ni-Fe, Ni-Fe-Mo, G, etc., which can be obtained by electron beam evaporation, ion blating, sputtering, etc.
o-Mo-Zr, Go-Ti, Co-Fe-B films, etc., and the perpendicular magnetization film is CoQr, C.

-Ti, Go-V, Go-Mo, Go-W, G
o -P, 0o-Or-Rh, etc., which can be obtained by electroless plating, vacuum evaporation, sputtering, or ion blating.

The plasma polymerized membrane used in the present invention includes monomers such as fluorocarbons, chlorofluorohydrocarbons, and fluorohydrocarbons.

Can be appropriately selected from silanes such as 9, and has a thickness of 10 Å.
If the above is the case, the effect can be easily reproduced. ○ Plasma polymerized films are characterized by the ability to make the physical properties uniform even in extremely thin films.
The crystalline and amorphous portions of polyester have been used to improve the variation in the orientation of the soft magnetic layer, which was difficult to control, and the same is true when forming a perpendicularly magnetized film without a soft magnetic layer. Since Δθ50 can be made small and uniform, noise is reduced and the S/N ratio at short wavelengths is improved.

A more specific example will be described below.

N was deposited on a 12 μm thick polyethylene terephthalate film with a crystallinity of 46% by high-frequency sputtering.
i-Fe film 0.4 μm (ai: s.

wt%), Go-Or film 0.15 μm (Cir:
20 wt %) and KNi-Fe via the plasma polymerized film of the present invention.

A comparative study was conducted on media provided with a Go-Or two-layer film.

Further, as another structure, a case where the Ni--Fe film was not interposed was also compared and studied in the same manner.

The apparatus used to form the plasma polymerized film was a modified winding evaporation machine that applied high-frequency waves to discharge electrodes with a radius of curvature of 3 (MW) and a circumferential length of 1 m arranged in an N-shape along a cylindrical can with a diameter of 50 α. (13,56MH2) is applied.

The physical properties of the obtained thin film and the results of evaluating its performance as a magnetic tape are summarized in a table.

As shown in the margins below, it can be seen that according to this example, the S/N ratio, which is important for performing high-density magnetic recording, is improved.

In addition, Ni can be applied directly to polyester with a crystallinity of 40 coefficients or less.
- In terms of S/N, it is about 2 dB even for conventionally known magnetic recording media formed with two-layer films of Fe and Go-Or.
It is improved at short wavelengths of 0.5 μm to 0.3 μm.

Of course, even when recording and reproducing Hi-Fe and Go-Or two-layer media using an auxiliary pole excitation type vertical head, there is a difference of 3 to 5 dB between the product of the present invention and the conventional product, which indicates that the high performance of the product of the present invention is It can be understood.

The effect of the present invention has been sufficiently confirmed not only in combinations of the above-mentioned materials of the present invention but also in sheet-shaped J disk-shaped media other than magnetic tapes.

Effects of the Invention As described above, the magnetic recording medium of the present invention has a crystallinity of 40
By forming a perpendicular magnetic recording layer by disposing a plasma-polymerized film on a polyester film of at least 10%, the variation in crystal orientation is reduced and the S/N ratio at short wavelengths is improved. Ki1,').

[Brief explanation of the drawing]

FIG. 1 is an enlarged sectional view of a conventional magnetic recording medium, and FIG. 2 is an enlarged sectional view of a magnetic recording medium of the present invention. 4... Polyester film, 5... Plasma polymerized film, 6... Soft magnetic layer, 7... Perpendicular magnetization film. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 2

Claims (1)

[Claims] A magnetic recording medium characterized in that a perpendicular magnetic recording layer is arranged on a plasma polymerized film on a Briester film with a crystallinity of 401% or more.