JPS60211617A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To obtain a medium which has good S/N and does not increase drop- out even after repeated use, is highly durable and is suitable for high-density recording by sticking fine inorg. particles coated with a plasma polymerized film onto a high polymer substrate. CONSTITUTION:The soln. prepd. by dispersing the fine particles formed by coating the surface of inorg. particles such as TiO2, SiO2, CaF2, CrO2, CaCO3 or the like having the grain size within a 100-1,000Angstrom range with a plasma polymerized film 3 of polyester, polyolefin, cellulose deriv., polyimide or the like to 100- 1,000Angstrom thickness into a binder resin soln. so as to be incorporated therein at 5- 10 pieces for each 1mum<2> the substrate surface is coated on the substrate 1 consisting of a polyester film, etc. and is dried to manufacture the above-mentioned substrate. The thin ferromagnetic film 4 is formed by sputtering, etc. on such substrate to form a vertical magnetized film. The high-density recording medium having high S/N, less drop-out and excellent durability is thus obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a magnetic recording medium whose magnetic recording layer is a ferromagnetic metal thin film suitable for high-density magnetic recording.

Conventional Structures and Problems There has been an increasing demand for high-density recording in recent years, and there is a strong desire to put into practical use magnetic recording media in which the magnetic recording layer is made of a ferromagnetic metal thin film.

Since all such media aim at high-density recording, the spacing loss is significant regardless of the recording method, and there is a natural limit to the film thickness that can be tolerated as a protective film.

We can apply and form fatty acids, fatty acid amides, fatty acid esters, silicone oil, fluorine oil, etc. using a wet coating method, or form a thin polymer film using a sputtering method targeting polymers such as Teflon, or start from various monomers. A method of forming a plasma-polymerized film has been proposed, and although it has been criticized, the thickness is insufficient to satisfy durability in terms of stable short-wavelength output and little dropout under a wide range of environmental usage conditions. 0.06 μ to nearly 0.1 μ is required, and the spacing loss is too large, so improvements are desired.

OBJECT OF THE INVENTION The present invention was made in view of the above circumstances, and provides a magnetic recording medium with low spacing loss, stabilization of short wavelength output with repeated use, and low dropout increase. The purpose is to

Structure of the Invention The magnetic recording medium of the present invention is characterized in that inorganic fine particles coated with a plasma polymerized film are arranged on a polymer substrate, and a ferromagnetic metal thin film is arranged thereon. The short wavelength output is large, and the output is stable even after repeated use, and the dropout increases.
There are also few.

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

The figure is a diagram showing the basic configuration of a magnetic recording medium in an embodiment of the present invention. In the figure, 1 is the substrate, 2 is the inorganic particle, and 3
4 is a plasma polymerized film, and 4 is a ferromagnetic metal thin film.

Substrates that can be used in the present invention include polyesters such as polyethylene terephthalate, polyolefins such as polypropylene, cellulose triacetate), cellulose derivatives such as nitrocellulose, polyamide, polyamideimide, polyparapanic acid, polyimide, etc. It will be done.

Ferromagnetic metal thin films that can be used in the present invention include:
Co, Fe formed by electron beam evaporation method, sputtering method, ion blating method, electroless plating method, etc.
, Nl, Co-Ni, Co-Fe, Co-Ce.

Co-Cr, Co-Cu, Co-B, Co-B1. Co
-Ge.

Co-La, Co-N7. Co-Mn, Co-Mo, C
o-P.

Co-Pt, Co-Ru, Co-Rh,
Co-3n +'Ctr-3m.

Co-8i, Co-Ti, Co-Ta,
Co-V, Co-W, C.

-Ni-Cr, Co-Cr-Rh, Co-N1-P, their partial oxide films, partial nitride films, etc., and are independent of the direction of the easy axis of magnetization.

The inorganic fine particles coated with the plasma polymerized film of the present invention can be produced by placing the inorganic fine particles in a plasma polymerization container. Another method is an evaporation method in which metals, oxides, etc. are evaporated in a plasma polymerization atmosphere.

As inorganic fine particles, 1008 to 1000 people, preferably 2008 to 500 panoTi○2,5i02°CaF
2. CaCO3, CrO2, WO3, Mo, Cr
, W, etc.

Monomers used to obtain the plasma polymerized film include fluorocarbons such as polytetrafluoroethylene and fluorinated polyethylene, chlorofluorohydrocarbons such as polychlorotrifluoroethylene, and fluorocarbons such as polyvinylidene fluoride and polyvinyl fluoride. Hydrocarbons, polyamides, polyimides, polycarbonates, polyphenylene oxides, hydrocarbons such as polyethylene, cyclic organic compounds containing heteroatoms such as allylamine, acrylamides, pyridine, ethylene oxide, tetraalkylsilane, trial The material is not limited, and may be a single or a mixture of 7-runs such as kiln run.

The thickness of the polymer film is from 100 to 1000, preferably 2
If the number of participants is o~400, the purpose of the present invention can be fully achieved.

The magnetic recording medium of the present invention can of course be provided with a surface protective layer within a known range.

One of the reasons why the structure of the present invention improves durability is that the contact area with the other side, such as a magnetic head, is reduced due to the shape effect. The contact condition with the head is stable,
The reason why the short-wavelength output envelope is so good is not necessarily clear, but one reason is that the plasma polymerized film is thought to have a subtle dielectric effect.

A more specific example will be described below.

On a polyethylene terephthalate film with a thickness of 12.17 zm, fine particles of various configurations were dissolved in a solvent (methyl ethyl ketone: toluene, 1:1 mixture) using polyester resin as a binder so that the particles were 5 to 10 particles per 1 μnf. A coated and dried substrate was prepared.

On this substrate, 1×1O
Co -N i (N i
, Section 19) A film with a thickness of 0.1 μm was formed.

As a comparative example, inorganic fine particles having approximately the same external dimensions as the fine particles of the present invention were placed on a substrate with the same density.
A 1 μm Co-Ni film was formed.

In each case, stearic acid dissolved in methyl isobutyl getone was applied as a surface protective layer to a dry thickness of 60 mm, and dried.

After applying a surface protective layer, slits were made into 8 skin widths, magnetic tape was applied, and a ferrite head (gap length 0.2μ
m) was repeatedly recorded and reproduced in each environment, and the S/N and dropout were measured for each number of passes. S/N is expressed in relative comparison in [dB] units, and draw and pull out are initial values (2
It is normalized by the value at the time of playback of the first pass) and expressed as a magnification.

As is clear from the margin table below, the product of the present invention has a stable S/N ratio and no increase in dropouts.

The reason why the S/N ratio is good is considered to be because the ferrite noise is stable and the state of contact between the tape and the head is judged to be good from the viewpoint of the envelope.

This tendency can be seen by forming a 0.2 μm perpendicularly magnetized film of CO・Cr (Cr20wt%) by high frequency sputtering method.
The same effect can be obtained with repeated recording and playback (recording wavelength 0.36 μm) using a Co-based amorphous head with a gear knob length of 0.19 μm, and with other combinations of materials and with disks and sheets other than tape as the media format. It was confirmed.

Effects of the Invention As described above, the magnetic recording medium of the present invention has a ferromagnetic metal thin film disposed on a polymer substrate, inorganic fine particles coated with a plasma polymerized film, and can be used repeatedly. S
/N is maintained, dropout does not increase, and it is durable, and its practical effects are particularly remarkable in short wavelength recording.

[Brief explanation of the drawing]

The figure is an enlarged sectional view of the magnetic recording medium of the present invention. 1. Polymer substrate, 2. Inorganic fine particles, 3. Plasma polymerized film, 4. Ferromagnetic metal thin film.

Claims (1)

[Claims] A magnetic recording medium characterized in that inorganic fine particles coated with a plasma polymerized film are arranged on a polymer substrate, and a ferromagnetic metal thin film is arranged thereon.