JPS629519A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To obtain a magnetic recording medium having excellent durability and high recording density by forming a metallic oxide-contg. layer on the surface of a thin ferromagnetic metallic film provided on a nonmagnetic substrate and forming a polyphosphazene-contg. layer on the surface of said layer. CONSTITUTION:The thin ferromagnetic metallic film 2 is formed on the nonmagnetic substrate 1. The metallic oxide-contg. layer 3 with is the oxide of any among Al, Fe, Si, Zr, Ti, W and Cr, or the ferrite expressed by the formula I or the composite glass consisting of silicon oxide and at least one selected from the group consisting of zirconia oxide, titanium oxide and tungsten oxide is formed on the surface of the film 2 and further the polyphosphazene- contg. layer 4 expressed by the formula II is provided on the surface thereof. The magnetic recording medium formed in such a manner has excellent lubricity and durability.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to high density magnetic recording media used in the information industry and the like.

With the demand for high-density recording of conventional technical information, organic binders
Instead of coating-type magnetic recording media in which ferromagnetic powder such as Fe 203 is dispersed, magnetic recording media in which a ferromagnetic metal thin film is directly deposited on a non-magnetic substrate such as plastic by vacuum evaporation, sputtering, ion plating, etc. Recording media have been researched and developed, and some are in practical use.

Problems to be Solved by the Invention In ferromagnetic metal media, the thin film layer easily peels off and wears out during contact scanning with a head during recording and reproduction.

This may cause damage, etc. In order to improve the above defects, it has been proposed to provide a protective film on the surface of the medium.

For example, Sio2. An203. A proposal has been made to form a composite protective film by forming a metal oxide layer such as the above, and forming a film of a fatty acid lubricant on the surface thereof (Japanese Patent Application Laid-open No. 154642/1983). However, in this case, the fatty acid-based lubricant has a weak bond with the underlying oxide layer and has low heat resistance, so it peels off and decomposes due to frictional heat during contact with the magnetic recording head, resulting in long-term problems. It has little effect on durability.

Means for solving the problem A metal oxide-containing layer is formed on the surface of a ferromagnetic metal thin film provided on a non-magnetic substrate, and a polyphosphazene-containing layer is formed on the surface of the metal oxide-containing layer for protection. Make it a membrane.

Function The metal oxide-containing layer on the surface of the ferromagnetic metal thin film improves wear resistance and increases the bonding force with the lubricant phosphazene.
Since detachment and decomposition are suppressed by the heat resistance and oxidation resistance of the lubricant itself, a magnetic recording medium with excellent durability and high recording density can be obtained.

Example The figure is a cross-sectional view of the magnetic recording medium of the present invention.

In the figure, 1 is a non-magnetic substrate, 2 is a ferromagnetic metal thin film, and 3 is a non-magnetic substrate.
4 is a metal oxide-containing layer, and 4 is a polyphosphazene-containing layer. The nonmagnetic substrate 1 that can be used in the magnetic recording medium according to the present invention is polyvinyl chloride.

Examples include films and plates made of well-known materials such as polymer materials such as polyethylene terephthalate, polyimide, and polyamide, non-magnetic metal materials such as aluminum, and ceramic materials such as glass and porcelain.

The ferromagnetic metal thin film 2 that can be used in the magnetic recording medium of the present invention is an alloy of one or more of iron, cobalt, and nickel, or an alloy of these with manganese and chromium.

There are alloys that combine titanium, phosphorus, yttrium, samarium, bismuth, etc. In order to form the ferromagnetic metal thin film 2 on the non-magnetic substrate 1, a well-known method such as a vacuum evaporation method, a sputtering method, an ion blasting method, a plating method, etc. is used. In the present invention, a metal oxide-containing layer 3 is formed on the ferromagnetic metal thin film 2 as described above, and a polyphosphazene-containing layer 4 is further provided on the surface thereof.

As the metal oxide layer 3 that can be used in the present invention, A2°0
3. Fe2o3, 5IO2, ZrO2, TiO2, WO
Examples include 2°CrO2, ferrite, and composite glass.

Ferrite has the general formula MO・Fe2o3 (in the formula, M is M
The composition is at least one selected from n, Co, Nl, Cu, and Zn.

Methods for forming the above-mentioned metal oxide-containing layer include a sputtering method, 9 reactive vapor deposition, and 2 reactive ion blating, and a coating method in which Al, Si, Zr, Ti, and W alcolade are hydrolyzed and polymerized. , especially St.
Alcorado, 2τ Alcorado, Ti Alcorado,
Composite glass films prepared by mixing any of the W Alcolades were effective in controlling physical properties such as the coefficient of thermal expansion and in mass production. In the case of CrO2, in addition to the above method, Co
By treating the -Cr-based ferromagnetic metal film with dilute nitric acid under certain conditions, it was possible to selectively form a CrO2 film on the magnetic thin film.

Polyphosphazene has the general formula; (wherein, m and m' are integers of 0 to 7, and n is 4 to
Particularly preferred are polyfluoroalkoxyphosphazenes represented by: When m and m' of the side chain molecules were 7 or more, heat resistance and lubricity decreased. If n in the main chain is less than 4, the heat resistance and bonding strength with the substrate will decrease, making it impossible to fully demonstrate durability. If n is 31 or more, the polyphosphazene will be poorly soluble in the solvent and the surface of the substrate will deteriorate. It was difficult to form a uniform film, and the protective film could not function as a protective film. The polyphosphazene-containing layer was formed by dissolving it in a solvent of ethanol, methyl isobutyl ketone, tetrahydrofuran, methyl ethyl ketone, dimethyl ketone, dimethyl formamide, or dimethyl sulfoxide, and forming a thin film in a coating process. The sum of the thickness of the metal oxide-containing layer and the thickness of the polyphosphazene-containing layer was preferably 50 to 600 people. 601
When it is more than Å, the output decreases due to spacing loss during signal reproduction, and when it is less than ω, it is difficult to form a uniform protective film, causing problems in wear resistance and lubricity.

This will be explained below using examples.

Example-1 Cobalt (90wt%)-chromium (1wtl) was deposited on a 20μm thick polyimide film substrate by vacuum evaporation method.
A ferromagnetic metal thin film with a thickness of 1600 nm was made. On the surface of this medium, an oxide layer of At203 was formed using a reactive vapor deposition method, and on the surface, polyditrifluoroethoxyphosphazene (m, m'=O, n
A 1 wt % ethanol solution of 4) was applied and dried to form a thin film with a thickness of 164 mm. The film thickness was measured using an ellipsometer (this method was used in all of the following). The sample shape was a 3.6 inch disk.

Example 2 On the surface of a ferromagnetic metal thin film having the same structure as in Example 1, a Zn ferrite thin film with a thickness of 105 oxides was provided by sputtering. Furthermore, 0.06 of polydipentafluoropropoxyphosphazene (m, m'=1, n=6) was added to the surface.
A wt% tetrahydrofuran solution was applied and dried to form a thin film of 210 people. The sample shape was prepared in the same manner as in Example 1.

Example-3 On a polyethylene terephthalate substrate with a thickness of 60 μm,
A composite solution of Si isopropylate and Zr impropylate (trade name Glass Power 401, manufactured by Chikaraita Institute) was applied to the surface of a 20oO ferromagnetic metal thin film consisting of cobalt (86%) and chromium (151) by sputtering. 100 in the presence of catalyst
It was hydrolyzed and polymerized at ℃ to form a glass film (thickness: 20 mm) having a composition of Zr0-3iO3. Furthermore, the surface of nipolyfluoroalkoxyphosphazene (m, m
(7) A mixed solvent solution of dimethylformamide and acetone (volume ratio 1:4) was applied and dried to form a thin film with a thickness of 120 people.

The sample was produced in the same shape as in Examples 1 and 2.

Example 4 A ferromagnetic metal thin film having the same structure as Example 3 was further coated with polyfluoroalkoxyphosphazene (m, m'=
6. A mixed solvent solution of 0.01 wt % dimethyl sulfoxide and tetrahydrofuran (volume ratio 1:3) of n = 25) was applied and dried to form a thin film with a thickness of 266 people to prepare a sample similar to the above example. did.

Comparative Example 1 A stearic acid-containing layer with a thickness of 200 mm was provided on a ferromagnetic metal thin film having the same structure as in Examples 1 and 2, and a sample having the same shape as in Example was prepared.

Comparative Example-2 On a ferromagnetic metal thin film having the same structure as Examples 3 and 4, an 8102 thin film with a thickness of 200 mm was provided by sputtering, and a perfluorolauric acid-containing layer was further formed on the surface with a thickness of 100 mm. did. A sample having the same shape as in the example was prepared.

Table 1 shows the results of examining the friction coefficient and durability of the media surface of each magnetic disk obtained in the above examples and comparative examples.
It was shown to. The test conditions are shown below.

a Friction test condition measuring device; Reciprocating static, dynamic friction coefficient automatic measuring device Head material, shape: Steel ball (SUJ) diameter 3 m/ml Load: 20 gr l Running speed: 1oIII/S Measurement atmosphere: 26℃ 6o%RH b Endurance test condition measuring device; disk type magnetic recording measuring device; head load; 1
0gr l Running speed: 3 m/S Measurement atmosphere: 25°C, 60% RH The number of running times until the output decreased by 3 dB from the initial value was measured.

Table 1 As is clear from the results in Table 1, the product of the present invention is excellent in both lubricity and durability. In addition to the implementation, 5io2
-TiO□, 5io2-WO2 composite glass and polyfluoroalkoxyphosphazene also produced similar effects.

Effects of the Invention The magnetic recording medium of the present invention has been confirmed to have excellent lubricity and durability, and is extremely useful in practice.

[Brief explanation of the drawing]

The figure is a cross-sectional view of a magnetic recording medium in an example of the present invention. 1...Nonmagnetic substrate, 2...Ferromagnetic metal thin film, 3...Metal oxide containing layer, 4...
- Polyphosphazene-containing layer.

Claims (5)

[Claims] (1) A magnetic recording medium in which a metal oxide-containing layer is formed on the surface of a ferromagnetic metal thin film provided on a non-magnetic substrate, and a polyphosphazene-containing layer is formed on the surface of the metal oxide-containing layer. (2) The metal oxide-containing layer is made of Al, Fe, Si, Zr,
The magnetic recording medium according to claim 1, which is an oxide of any one of Ti, W, and Cr. (3) The metal oxide-containing layer has the following general formula: MO・Fe
_2O_3 (In the formula, M is Mn^2^+, Fe^2^+, Co^2^
+, Ni^2^+, Cu^2^+, and Zn^2^+. 2. The magnetic recording medium according to claim 1, which is a ferrite represented by: (4) The magnetic recording medium according to claim 1, wherein the metal oxide-containing layer is made of a composite glass made of silicon oxide and at least one selected from the group consisting of zirconia oxide, titanium oxide, and tungsten oxide. (5) Polyphosphazene is a polyphosphazene represented by the following general formula; ▲There are mathematical formulas, chemical formulas, tables, etc.▼ The magnetic recording medium according to claim 1, which is fluoroalkoxyphosphazene.