JP2524522B2 - Magnetic recording media - Google Patents

Description

The present invention relates to a ferromagnetic metal thin film type magnetic recording medium having a protective film made of a rust preventive agent. More specifically, the present invention relates to a ferromagnetic metal thin magnetic recording medium having a protective film of an anticorrosive agent containing alcohol or ether having a triple bond in the molecule as a main component.

[Prior Art] A magnetic recording medium that has been widely used in the past is a coating type in which a magnetic coating mainly composed of acicular magnetic powder and a polymer binder is coated on a non-magnetic substrate to form a magnetic layer. Magnetic recording medium.

At present, the magnetic recording / reproducing apparatus tends to have a higher density, and a magnetic recording medium having excellent short wavelength recording characteristics is desired.

However, there is a limit to the improvement of the short wavelength recording characteristic of the coating type magnetic recording medium. On the other hand, Co, CoNi, CoNiP, Co
A metal thin film magnetic recording medium in which a ferromagnetic material containing Co as a main component such as Cr is formed on a non-magnetic substrate by a so-called physical vapor deposition method such as vacuum vapor deposition, sputtering, or ion plating is Since a non-magnetic binder is not mixed, a remarkably high residual magnetic flux density can be obtained, and since the magnetic layer can be formed extremely thin, high output and short wavelength response are excellent. Have. Due to this feature, thin-film magnetic recording media have recently become the mainstream of magnetic media.

[Problems to be Solved by the Invention] The thin-film magnetic recording medium has a high magnetic recording density and excellent short-wavelength recording characteristics, but on the other hand, Co is relatively easily corroded and the magnetic layer is exposed. It has a drawback that it is poor in corrosion resistance and easily deteriorates magnetically, which is a serious problem in practical use.

A method of adsorbing various organic compounds to the medium in order to prevent corrosion of the metal thin film type magnetic recording medium in the atmosphere has been proposed (for example, JP-B-62-18971 and JP-A-62-172520). 62-172526 and 62
-172530 gazette). All of these organic compounds are adsorbed on the surface of the ferromagnetic metal, and are expected to have a protective effect against corrosion factors in the atmosphere.

However, in actual atmospheric corrosion, not only water, but also electrolytes such as chlorides and sulfates and gases such as SO ₂ are significant. The adsorption of the compounds disclosed in the above publications is effective in a humid atmosphere and SO ₂ gas, but has little effect on corrosion involving chlorine.

An object of the present invention is to provide a metal thin film type magnetic recording medium is also excellent in corrosion resistance against corrosion chlorine is involved in other humid atmosphere or SO ₂ gas.

[Means for Solving the Problems] The above object is achieved by providing a rust preventive agent layer containing alcohol or ether having a triple bond in the molecule as a main component on the ferromagnetic metal thin film layer.

[Operation] As a result of the extensive experiments and researches conducted by the present inventors over the years, as a result of adsorbing a rust preventive agent having a triple bond in its molecule as a main component of alcohol or ether on the ferromagnetic metal layer, It was discovered that the anticorrosion effect against corrosion is dramatically enhanced.

The exact mechanism of rust prevention has not been clarified yet, so it is beyond speculation.However, in atmospheric corrosion, salt etc. are detected especially in the corroded part, so corrosion is caused by chloride adhering to the surface. Is believed to progress. That is,
It is considered that chloride, which is an electrolyte, is ionized by moisture and combines with hydrogen ions in the adsorbed water to form hydrochloric acid, which corrodes the magnetic layer. It is considered that alcohols or ethers having a triple bond in the molecule exert a remarkable rust preventive effect by forming a protective film having a high anticorrosive effect on the transition metal in hydrochloric acid.

Thus, the rust preventive agent containing alcohol or ether as a main component can effectively prevent atmospheric corrosion of the ferromagnetic metal thin film layer.

Examples The alcohols having a triple bond in the molecule that can be used in the present invention are monohydric, dihydric or trihydric alcohols.
Monohydric or dihydric alcohols are preferred. Examples of such alcohols include 2-butyne-1,4-diol, 1-butyn-3-ol, 2-butyn-1-ol, 3-butyne-
1-ol, 2-decyn-1-ol, 3-decyn-1-ol, 3,6-dimethyl-1-heptin-3-ol, 2,5-
Dimethyl-3-hexyne-2,5-diol, 3,5-dimethyl-1-hexyne-3-ol, 3,6-dimethyl-4-octyne-3,6-diol, 3,4-dimethyl-1- Pentin-3-ol, 3-ethyl-1-heptin-3-ol, 4
-Ethyl-1-hexyn-3-ol, 3-ethyl-5-
Methyl-1-heptin-3-ol, 4-ethyl-1-octyne-3-ol, 3-ethyl-1-pentyn-3-ol, 1-ethynyl-1-cyclohexanol, 1-heptin-3-ol , 2-heptin-1-ol, 3-heptin-1-ol, 4-heptin-2-ol, 5-heptin-
3-ol, 2,4-hexadiyne-1,6-diol, 3-hexyne-2,5-diol, 1-hexyne-3-ol, 2-
Hexin-1-ol, 3-hexyn-1-ol, 4-hexyn-2-ol, 5-hexyne-1-ol, 5-hexyne-3-ol, 1-methoxy-1-buten-3-yne, 3-methyl-1-butyn-3-ol, 5-methyl-1
-Hexyne-3-ol, 3-methyl-1-heptin-3
-Ol, 3-nonyl-1-ol, 1-octin-3-ol, 3-octin-1-ol, 10,12-pentacosadiin-1-ol, 1-pentin-3-ol, 2-pentin-1 -Ol, 4-pentyne-1-ol, 4-pentyne-
2-ol, 3-pentyn-1-ol, 1-phenyl-2
-Propyn-1-ol, 1-phenylpropargyl alcohol, 2-propyn-1-ol, 2,4,7,9-tetramethyl-5-decyn-4,7-diol and 10-undecyn-1-ol Is. Other alcohols can of course be used.

The ether which can be used in the present invention is, for example, methyl propargyl ether or 2-butyne-1,4-diol bis (2-hydroxyethyl) ether. Other ethers can of course be used.

These alcohols and ethers alone,
Alternatively, two or more types can be used in combination. Further, these can be used by dissolving, suspending, mixing or diluting with an appropriate solvent.

The alcohols and ethers of the present invention can be used in combination with other conventionally used rust preventives. Such rust preventive agents include, for example, benzotriazole,
Examples include benzotriazole derivatives, naphthols, quinolines and quinones. When used in combination with such a conventional rust preventive, the alcohols and ethers of the present invention are preferably blended in an amount of 10 wt% or more in a weight ratio with other rust preventives.

The method of forming the rust preventive agent layer itself is not an essential requirement of the present invention. For example, it can be formed by various methods such as coating by a conventional method such as a dipping method, a gravure roll method, a spin coating method, or a direct metal film formed on a ferromagnetic metal thin film by vacuum vapor deposition. The alcohols or ethers of the present invention are preferably applied so as to be adsorbed on the ferromagnetic metal thin film layer.

Although the thickness of the rust preventive agent layer itself is not an essential requirement of the present invention,
Generally, it is preferably in the range of 50Å to 500Å. When it is less than 50Å, it is difficult to form a rust preventive agent layer having a uniform thickness, while when it exceeds 500Å, spacing loss becomes excessive, which is not preferable.

The magnetic recording layer in the magnetic recording medium of the present invention is made of Co alone or a Co alloy such as Co-Ni, Co-Cr, Co-P and Co-Ni-P, and is formed by means of vacuum deposition, sputtering, ion plating or the like. It is deposited and formed on a substrate. Other ferromagnetic metals can also be used. It can also contain oxygen.

As the magnetic recording medium, polyester, polyimide,
Magnetic tapes based on synthetic resin films such as polyethylene, magnetic disks and magnetic drums based on discs and drums composed of synthetic resin, aluminum, glass, etc., and various types of structures that come into sliding contact with the magnetic head at the start and stop. Includes forms.

 Hereinafter, the present invention will be described in more detail with reference to specific examples.

Examples 1 to 5 Using a polyethylene terephthalate non-magnetic substrate having a thickness of 10 μm, a Co—Ni alloy (Ni 20 at%) thin film layer was formed by electron beam melting in a vacuum chamber into which oxygen gas was introduced. On this thin film, 2-butyne-1,4-diol (Example 1), 2,4
-Hexadiyne-1,6-diol (Example 2), methylpropargyl ether (Example 3), 1-phenyl-2-
Propin-1-ol (Example 4) and 2-butyne-
A rust preventive agent containing 1,4-diol bis (2-hydroxyethyl) ether (Example 5) as a main component was applied to prepare a magnetic recording medium.

Comparative Examples 1 to 3 Instead of alcohol or ether as a rust inhibitor,
A magnetic recording medium was prepared according to the conditions described in the above-mentioned examples except that p-benzoquinone (Comparative Example 1), benzothiazole (Comparative Example 2) and resorufene (Comparative Example 3) were used.

Each magnetic recording medium produced as described above was heated at 60 ° C and 90 ° C.
It was placed in an atmosphere of% RH and in a hundred-leaf box and exposed to the atmosphere. Then, the generation of rust on the ferromagnetic metal thin film layer was visually observed.
The results are summarized in Table 1 below.

As is clear from the results shown in Table 1, the rust preventive agent containing alcohol or ether having a triple bond in the molecule as a main component has a significantly higher anticorrosive effect in the atmosphere than conventional rust preventive agents.

Example 6 As a ferromagnetic metal thin film, a 1500 nm thick CoNi magnetic film (Co
80at%, Ni20at%) was formed. A 0.1 wt% isopropyl alcohol solution of 5-nitrobenzotriazole was used as a rust preventive agent. Further, 1-phenylpropargyl alcohol was added to this solution as an alcohol having a triple bond.
It was added at a concentration of 0.05 wt%. This mixed solution was applied on the CoNi magnetic film at a rate of ³ to 50 ml / m ² .

Example 7 A magnetic recording medium was produced according to the conditions described in Example 6 except that nitrosohydroxyquinoline was used as the rust preventive agent.

Example 8 A magnetic recording medium was produced according to the conditions described in Example 6 except that nitrosonaphthol was used as the rust preventive agent.

Example 9 A magnetic recording medium was produced according to the conditions described in Example 6 except that 1,2-naphthoquinone was used as the rust preventive agent.

Example 10 A magnetic recording medium was produced according to the conditions described in Example 6 except that propargyl alcohol was used as the triple bond-containing alcohol.

Comparative Example 4 A magnetic recording medium was produced according to the conditions described in Example 6 except that 1,3,4-thiadiazole was used as the rust preventive agent and the triple bond-containing alcohol or ether was not added.

Comparative Example 5 A magnetic recording medium was produced according to the conditions described in Example 6 except that cuperone was used as a rust preventive and no alcohol or ether was added.

Comparative Example 6 A magnetic recording medium was produced according to the conditions described in Example 6 except that 1,3,4-thiadiazole was used instead of 5-nitrobenzotriazole as a rust preventive agent.

The magnetic recording media prepared in the above Examples and Comparative Examples were placed in a hundred-leaf box and subjected to an exposure test in the atmosphere for 7 days, and the presence or absence of corrosion was checked and the corroded portion was analyzed by EDX. Further, these media were exposed to an atmosphere of 60 ° C. and 90% RH for 1 week, and the reduction rate of the saturation magnetization (Ms) after the exposure was measured. The results are summarized in Table 2 below.

As is clear from the results shown in Table 2, an alcohol having a triple bond in the molecule, which uses a rust preventive that forms a sufficient corrosion-resistant protective film and has a high effect of suppressing corrosion by chlorine in addition to this. Alternatively, addition of ether can exert a remarkable anticorrosion effect against atmospheric corrosion.

[Effects of the Invention] As described above, the anticorrosive effect against atmospheric corrosion is dramatically improved by adsorbing the anticorrosive agent having a triple bond in its molecule and containing alcohol or ether as a main component on the ferromagnetic metal layer. To be enhanced.

In particular, a rust preventive agent containing an alcohol or an ether having a triple bond in its molecule as a main component exhibits an excellent anticorrosive effect against corrosion by hydrochloric acid.

By mixing an alcohol or ether having a triple bond in the molecule with a specific rust preventive and using them together, a more remarkable anticorrosive effect against atmospheric corrosion can be exhibited.

Claims (6)

(57) [Claims] 1. A ferromagnetic metal thin film layer is provided on a non-magnetic substrate,
A magnetic recording medium, characterized in that an anticorrosive layer containing alcohol or ether having a triple bond in the molecule as a main component is provided on the ferromagnetic metal thin film layer. 2. The magnetic recording medium according to claim 1, wherein a rust preventive agent layer containing alcohol having a triple bond in the molecule as a main component is provided on the ferromagnetic metal thin film layer. 3. The magnetic recording medium according to claim 1, wherein a rust preventive agent layer containing ether having a triple bond in the molecule as a main component is provided on the ferromagnetic metal thin film layer. 4. A ferromagnetic metal thin film layer is provided on a non-magnetic substrate,
A magnetic recording medium characterized in that a rust preventive agent layer comprising a mixture of at least one of alcohol or ether having a triple bond in the molecule added to a rust preventive agent is provided on the ferromagnetic metal thin film layer. 5. The rust preventive agent comprises at least one component selected from the group consisting of benzotriazole, benzotriazole derivatives, naphthols, quinolines and quinones. Magnetic recording medium. 6. The magnetic recording medium according to claim 1, wherein the ferromagnetic metal thin film layer is made of Co alone or a Co alloy.