JPH0734261B2 - Magnetic recording medium - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high recording density magnetic recording medium applied to the information industry field and the like.

Conventional technology γ-Fe ₂ O ₃ and Co-containing γ-Fe ₂ O _{3 have been} developed for the purpose of developing magnetic recording media used for magnetic disks and magnetic tapes.
Alternatively, instead of a coating type magnetic recording medium prepared by dispersing ferromagnetic powder such as CrO ₂ in an organic binder, currently, for the purpose of further increasing the density, a ferromagnetic metal thin film is directly plated on a non-magnetic substrate by sputtering or sputtering. The development of metal thin film magnetic recording media formed by the method, vacuum deposition method, ion plating method, etc. is active.

However, the above-mentioned metal thin film magnetic recording medium causes unstable running property due to friction and wear due to contact with a magnetic head or the like under high-speed relative motion during recording / reproduction of signals, resulting in wear powder or damage. It cannot withstand long-term use. Therefore, it is strongly desired for practical use that the magnetic recording medium keeps smooth running property and wear resistance under the use environment condition.

For this reason, various improvements have been made such as improving the abrasion resistance and abrasion resistance by treating the magnetic layer or the surface thereof conventionally. For example, a fluorine-based hydrocarbon having a specific active group is laminated as a protective film. There are cases where
58-29147 report).

Problems to be Solved by the Invention However, although the above structure certainly shows some improvement in lubricity, it has insufficient points such as the phenomenon such as the peeling or deterioration of these in due course. ing. Therefore, in view of the above points, the present invention forms a base layer having good adhesiveness and excellent wear resistance on both the magnetic layer and the lubricating layer, so that good running property and durability with a magnetic head or the like can be obtained. It is an object of the present invention to provide an excellent magnetic recording medium.

Means for Solving the Problems An underlayer containing a ferrite compound is formed on the surface of a magnetic layer provided on a non-magnetic substrate, and a polymer film of p-xylylene or its derivative is laminated thereon as a lubricating layer. To form a magnetic recording medium.

Action Due to the presence of the underlayer, the abrasion resistance and adhesive force of the layer itself act to maintain the low friction property of the lubricating layer, whereby a magnetic recording medium excellent in running property and durability can be obtained. .

This is probably because while the ferrite compound-containing layer of the underlayer chemically bonds to the surface of the magnetic layer, it also has good adhesiveness to the polymerized film of p-xylylene or its derivative, which contributes to the improvement of anti-blocking property and the synergistic effect of lubricity. It is thought that it was done.

Example FIG. 1 is a sectional view of a magnetic recording medium of the present invention. In the figure, 1 is a non-magnetic substrate, 2 is a magnetic layer, 3 is a base layer containing a ferrite compound, and 4 is a lubricating layer made of a polymerized film of p-xylylene or its derivative.

Examples of the non-magnetic substrate 1 that can be used in the magnetic recording medium of the present invention include polymer materials such as polyamide, polyimide, polysulfone, polycarbonate, polypropylene, polyethylene, polyethylene terephthalate, poly (cellulose acetate), and polyvinyl chloride, non-magnetic metal. Material, glass,
There are films and plates made of known materials such as ceramic materials such as porcelain.

Further, as a ferromagnetic material forming the magnetic layer 2, Fe, Co, Ni
At least one metal selected from the group, or M and these
There are n, Cr, Ti, P, V, Sm, Bi, etc., or alloys combining these oxides. Among them, the magnetic layer composed of at least two elements selected from Co, Cr, and Ni has a high magnetic anomaly. It is preferable in that it has anisotropic energy and corrosion resistance, and these can be formed by a method such as a vacuum vapor deposition method, a sputtering method, an ion plating method, and a plating method.
Further, if the surface of the magnetic layer 2 is oxidized by an ordinary wet method of treating with an oxidizing agent such as chromic acid or nitric acid or a dry method of introducing oxygen during formation of the magnetic layer to the extent that the magnetic properties are not affected, lubrication occurs. It is more preferable because adhesion with the layer and abrasion resistance are improved.

In the present invention, the ferrite compound-containing layer used for the underlayer 3 is an oxide of Fe or Mn, Zn, C in an appropriate ratio.
Each of u, Co, Ni, and Cr is a complex oxide in which each of them is mixed alone or in plural, and can be easily formed by sputtering by using the target of the target component.

It is considered that these films have excellent wear resistance because they are dense and have high strength.

On the other hand, the lubricating layer 4 is a polymerized film of p-xylylene or its derivative and has the following general formula: In indicated, R represents -CH _3, -C ₂ H _5, alkyl groups such as _{-C 3 H 7, -CH 2 OH} , hydroxyalkyl groups such as -C ₂ H ₅ OH, -
_{CH 2 OCH 3, -CH 2 OC} 2 H 5, -C 2 H 5 OCH 3 alkoxyalkyl groups such as, -OCH _3, alkoxy groups such as -OC ₂ H _5, -COOC
H _3, -COOC carboalkoxy groups such as ₂ H _5, a carboxyl group, a hydroxyl _{group, -CH 2 NH 2, -NH 2} , an amino group, such as -C ₂ H ₅ NH _2, a cyano group, a nitro group, F, Cl It is a polymer film having a halogen group, an aryl group or an alkenyl group of Br, I, and having one or more of each. n is 10 to 10000, and preferably 4000 or more. Since these are easily formed at room temperature by the vapor phase thermal decomposition method, they are formed into a desired film thickness without damaging the recording medium.

It is considered that these polymerized films have good physical properties because they have high tensile strength and molecular cohesive energy, and also have excellent properties because they have good chemical stability and environmental resistance. Above all, p-xylylene, chloro or dichloro p
-The polymerized film of xylylene has good adhesion to metal oxides,
It is more preferable because it has a high Young's modulus.

As described above, by sequentially forming the underlayer and the lubricating layer on the magnetic layer, it is possible to obtain a recording medium excellent in running property and abrasion resistance. The thickness of these layers may be thin, but naturally there is a limit in consideration of the coating property and the uniformity of the film due to the limit caused by the film forming method. Therefore, the upper limit of the thickness is preferably 500 A or less within the range that does not hinder the reduction of the recording output due to the spacing loss.

Hereinafter, detailed description will be made in Examples.

Example 1 On a polyimide film substrate having a thickness of 12 μm, Co—Cr (element ratio Co: Cr = 8: 2) was used to form a film with a thickness of 13000 A (AES
(Sample N)
o.1).

Targeting the oxide of Fe with a diameter of 50 mm and a thickness of 6 mm on the magnetic layer, the argon gas pressure in the bell jar (including oxygen gas 20% v / v) was 10 ^-2 Tor at a frequency of 13.56 MHz and 200 W.
An underlayer of ferrite of 150 A was formed by r. Then, p-xylylene dimer was further added thereto by a gas phase pyrolysis method.
Pyrolysis was performed under the conditions of 0.5 Torr and 60 ° C., and a poly (p-xylylene) film was formed at about 100 A at 25 ° C. and 0.1 Torr to form a lubricating layer (Sample No. 2).

For comparison, a solution obtained by diluting C ₇ F ₁₅ COOH with trichlorotrifluoroethane by 100 times (weight ratio) was spin-coated (film thickness 300A) to form a protective layer, which was designated as sample No. 3.

The above samples were compared and evaluated by measuring the dynamic friction coefficient, and the results are shown in Table 1.

The evaluation device was a reciprocating type dynamic friction coefficient, and a φ6.3 mm steel ball (SUJ2) was used for the head, and the load (P) = 10 gf and running speed (v) = 5.5 mm / sec were tested.

According to Table 1, the untreated sample No. 1 has a large μ value from the initial stage, scratches become clear after about 10 passes during running, and the μk value starts to fluctuate. Abrasion powder was intense and permeation scratches were seen. And sample N
In o.3, the initial runnability is 0.11, which is a small improvement,
As the car continued to run, scratches occurred, and the μk value increased to 0.38 on 300 Pass, which was not good.

However, in sample No.2, the μk value was small from the beginning, and it was 0.21 even after 300 passes, showing almost no change.
In addition, the surface was observed with good results such as almost no scratches.

Therefore, it is understood that the recording medium in which the underlayer containing a ferrite compound and the lubricating layer of poly (p-xylylene) are sequentially laminated on the magnetic layer is a magnetic recording medium having good running properties and excellent wear resistance.

Example 2 A sample having a film thickness of 1500 A was prepared on the polyimide film substrate having a film thickness of 30 μm with the same metal composition as in Example 1. At this time, oxygen was introduced during the deposition of the magnetic layer to form an oxide film layer of 75 A (Sample No. 4).

Fe-Ni (weight ratio 80:20), Fe-Cr (88: 12w)
(t%) target was prepared in the same manner as in Example 1. At the time of sputtering, introduce oxygen gas at the same time (25% v /
v), the underlayer having a thickness of 130A and 220A was formed. Then, a sample in which 100 A of poly (dichloro-p-xylylene) was laminated thereon was prepared, and these were designated as sample Nos. 5 and 6.

Then, the dynamic friction coefficient of these was measured under the test conditions shown in Table 2.

From the above, among these, Sample No. 4 was not good in that the μk value increased after 300 Pass and much friction powder was generated as in Example 1. In contrast, sample Nos. 5 and 6 have μ
It was also found that k was as small as 0.20 and 0.18, and no abrasion powder was generated even after running, and the abrasion resistance and abrasion resistance were excellent.

Therefore, the sample having the lubricating layer of the underlayer containing the ferrite compound and the polymer film formed from the derivative of p-xylylene such as poly (dichloro-p-xylylene) has excellent abrasion resistance and abrasion resistance. It is apparent that the present invention can be realized as a recording medium, and the same effect can be obtained even when the surface portion of the magnetic layer is oxidized.

Example 3 The samples having the configurations shown in Table 3 were evaluated by a pin-disk type tester. At this time, in Samples Nos. 9 and 10, the magnetic layer was surface-oxidized, and the underlayer and the lubricating layer were vapor-deposited after sputtering the substances shown in the same manner as in Examples 1 and 2, respectively, and the composition of The film thickness at that time is shown in parentheses below. In addition, the composition of the underlayer uses a target having the same mixing ratio as in Examples 1 and 2 with respect to other elements of Fe. For example, in sample No. 7, a composite oxide of Fe and Zn is formed. Indicates that. The lubrication layer is poly-
Only the substituent R of the p-xylylene polymer film is shown.
And the test condition is φ6mm ferrite head (width 500μ
m), P = 5 gf, v = 3.75 m / s, and μk values after 60 min were compared with the surface observation of each sample.

According to Table 3, samples No. 7 to No. 11 all have excellent characteristics such as a small μk value of 0.2 or less, and almost no running scratches observed on the surface. Since this can be achieved within the film thickness of 500 A, it can be said that the magnetic recording medium is effective in a range that does not affect the spacing loss and can be practically used.

EFFECTS OF THE INVENTION According to the present invention, an excellent magnetic recording medium having improved wear resistance and good running stability can be obtained.

[Brief description of drawings]

FIG. 1 is a sectional view of a magnetic recording medium according to an embodiment of the present invention. 1 ... Non-magnetic substrate, 2 ... Magnetic layer, 3 ... Underlayer, 4 ...
… Lubrication layer.

Claims (3)

[Claims] 1. An underlayer containing a ferrite compound is formed on the surface of a magnetic layer provided on a non-magnetic substrate, and a polymer film of p-xylylene or its derivative is laminated on the upper surface as a lubricating layer. And a magnetic recording medium. 2. The magnetic recording medium according to claim 1, wherein the lubricating layer is a polymerized film of p-xylylene, chloro or dichloro p-xylylene. 3. The total film thickness of the underlayer and the lubricating layer is 500 A.
The magnetic recording medium according to claim 1, which is as follows.