JPH034966B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a thin film magnetic recording medium. (Prior art) As magnetic recording media such as magnetic tapes, ferromagnetic thin films are formed using ferromagnetic metals such as Fe, Co, Ni, etc. by vacuum evaporation or ion plating, instead of the conventional coating method. Thin film types have come into use. This thin-film type magnetic recording medium has the advantage that it has a higher recording density than a coated type and can be made smaller. (Problems to be Solved by the Invention) By the way, ferromagnetic thin films usually have the disadvantage of low weather resistance and easy wear, and to improve this, a protective layer is provided on the surface of the ferromagnetic thin film. However, the conventional protective layer is not practically sufficient and has the disadvantage that, for example, the still life is large immediately after the protective layer is formed, but it tends to deteriorate over time. The present invention aims to improve the above-mentioned drawbacks and provide a magnetic recording medium with excellent still life characteristics. (Means for Solving the Problems) In order to achieve the above object, the present invention provides a magnetic recording medium in which a ferromagnetic thin film and a protective layer are sequentially formed on a non-magnetic substrate. The present invention provides a magnetic recording medium characterized by providing a protective layer containing at least one type of saturated fatty acid amide and at least one type of saturated fatty acid, saturated fatty acid amide, and halogenated fatty acid as main components. (Function) In the present invention, the protective layer contains at least one type of unsaturated fatty acids, their esters, and unsaturated fatty acid amides, and at least one type of saturated fatty acids, saturated fatty acid amides, and halogenated fatty acids as main components. As a result, the still life characteristics can be improved compared to conventional protective layers, and in particular, the durability against changes over time can be improved. (Examples) Hereinafter, the present invention will be described based on Examples. A polymer film such as a polyester film is used as the non-magnetic substrate. The ferromagnetic thin film is made of Fe,
It is formed by depositing Co, Ni, alloys thereof, etc. on the surface of a nonmagnetic substrate by vacuum evaporation, ion plating, sputtering, etc. The protective layer contains oleic acid, linoleic acid, linolenic acid, eleostearic acid, linoleic acid, linoleic acid, linolenic acid, linoleic acid, linoleic acid, linolenic acid, linoleic acid, linolenic acid, linoleic acid, linolenic acid, linoleic acid, linoleic acid, linolenic acid, linoleic acid, linoleic acid, linolenic acid, linoleic acid, linoleic acid, linolenic acid, etc. Unsaturated fatty acids such as elaidic acid and erucic acid, their esters,
At least one type of unsaturated fatty acid amide (hereinafter referred to as substance A), a saturated fatty acid such as a higher fatty acid, preferably a higher fatty acid having a carbon number greater than or equal to stearic acid, a saturated fatty acid amide, and a portion of the hydrogen of the alkyl group of the fatty acid. Contains at least one type of halogenated fatty acid (hereinafter referred to as substance B) to which a halogen element is added or substituted, and the solution is applied and
Dry and form. Furthermore, the weight ratio of substance A and substance B is A/B.
=0.05 to 0.4 is more preferable in terms of improving still life characteristics. Next, when changes in still life were measured for the above examples, the results shown in the table were obtained.

[Table] The manufacturing conditions are as follows: The non-magnetic substrate is a polyester film with a thickness of 10 μm, and the ferromagnetic thin film is Co:Ni=
An 8:2 alloy was formed to a thickness of 1000 Å by vacuum evaporation, and a protective layer was coated to a thickness of 500 Å by dissolving a solution of the combination of substances shown on the table in a solvent with a ratio of alcohol:toluene = 1:1. It is assumed that it was formed by The still life measurement conditions were as follows: The sample magnetic tape was placed on an 8 mm video deck, and the still life was defined as the time until the video output decreased to 1/2.
Measure after leaving it for a month. From the table, in the examples of the present invention, the combination of unsaturated fatty acids, etc. and saturated fatty acids, etc. can provide a stable magnetic recording medium that has a long still life of 40 minutes or more and does not change even after one month. On the other hand, in the case of a comparative example containing only saturated fatty acids, the still life after one month was significantly lower than the initial value and was 30 minutes or less. That is, it is clear that the former greatly improves the stability of still life. Note that the combination of fatty acid amide and fatty acid ester has lower properties than the combination of other fatty acids, and in particular, Comparative Example 4, which combines a saturated fatty acid amide and a saturated fatty acid ester, is extremely difficult to coat. The still life is also the initial value and after one month.
It has become significantly shorter, lasting less than 10 minutes. In the above embodiment, components other than substance A and substance B are impurities, but other additives may be added. (Effects of the Invention) As described above, according to the present invention, since the protective layer is mainly composed of a substance consisting of a combination of unsaturated fatty acids and saturated fatty acids, weather resistance can be improved and the still life deteriorates due to neglect. By reducing this, a practical magnetic recording medium can be obtained.

Claims (1)

[Claims] 1. In a magnetic recording medium in which a ferromagnetic thin film and a protective layer are sequentially formed on a nonmagnetic substrate, at least one of unsaturated fatty acids, their esters, and unsaturated fatty acid amides, and at least one of saturated fatty acids, saturated fatty acid amides, and halogenated fatty acids. A magnetic recording medium characterized by being provided with a protective layer containing at least one type of material as a main component.