JPS59146462A - Optical recording medium - Google Patents

Abstract

PURPOSE:To prevent substantially the corrosion of a recording layer by providing a rust preventive into an internal space of an optical recording medium of a sandwich structure. CONSTITUTION:Recording magnetic layers 2 and 2' made of an amorphous magnetic matter are formed on glass substrates 1 and 1' respectively. Two units of such recording media are sandwiched via spacers 3 and 3' so that the faces opposite to the faces of both magnetic layers touching the substrates are set opposite to each other. In this case, a powder type vapor phase rust preventive 4 is enclosed into an air layer 8. This preventive 4 uses dicyclohexyl ammonium nitrite, an amine material, a reactant of dicyclohexyl amine and octanonic acid.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in an air sandwich structure optical recording medium used for video discs, optical memories, magnetic recording, etc., and on which information can be written or read optically.

A typical example of the above-mentioned optical recording medium is a photothermal magnetic recording medium that uses a ferromagnetic thin film as a recording layer. The present invention will be explained below using this photothermal magnetic recording medium as an example.

Conventionally, MnBi, Mn
Polycrystalline thin films such as CuBi, GdCo, GdFe, Tb
Amorphous thin films such as Fe, DyFe, GdTbFe, and TbDyFe, and amorphous thin films such as GdIG are known.

Among these thin films, the film forming performance when manufacturing a large-area thin film at a temperature near room temperature, the writing efficiency for writing signals with small photothermal energy, and the S
In consideration of the readout efficiency for reading with a good /N ratio, the amorphous thin film has recently been considered to be excellent for use in photothermal magnetic recording media. In particular, GdTbFe has a large Kerr rotation angle and a Curie point of around 150° C., making it optimal for photothermal magnetic recording media.

However, amorphous magnetic materials such as GdTbFe generally have poor corrosion resistance, and have the drawback that they are corroded in a humid atmosphere, resulting in deterioration of magnetic properties.

In order to eliminate these drawbacks, conventional methods have been to provide a protective layer on the recording magnetic layer made of an amorphous magnetic material, or to create a disc-shaped photothermal magnetic recording system with an air sandwich structure in which the recording magnetic layer is sealed with an inert gas. medium is proposed. An example of such a disk-shaped photothermal magnetic recording medium will be described with reference to FIG. 1, which is a schematic longitudinal cross-sectional view of the disk-shaped photothermal magnetic recording medium. SiO layers 6, 6' are vacuum-deposited by electron beam heating. On this SiO layer, recording magnetic layers 2 and 2' of GdTbFeCo are formed using a high-frequency sputtering device, and protective layers 7 and 7' of Al film are vacuum-deposited thereon by electron beam heating. Then, spacers 3 and 3' are sandwiched between the two recording media thus produced, and Ar gas is filled in the inner space to produce a disk-shaped photothermal magnetic recording medium. With this structure, corrosion of the recording magnetic layer is well prevented, but equipment for vacuum deposition of the protective layers 7, 7' is required, and manufacturing time is required, resulting in a high price. Furthermore, if the protective layers 7, 7' are missing or if Ar gas is not sealed, corrosion of the recording magnetic layer cannot be sufficiently prevented.

An object of the present invention is to provide a photothermal magnetic recording medium having an air sandwich structure in which corrosion of the recording layer is substantially prevented.

Another object of the present invention is to provide an optical recording medium having an air sandwich structure that is excellent in mass productivity and highly reliable.

These objectives are achieved by the following optical recording medium.

An air sandwich in which two recording media including recording layers formed on a substrate face each other with an internal space containing air or inert gas sandwiched between them, with the recording layers facing the internal space. 1. An optical recording medium having a structure, characterized in that a rust preventive agent is present in the internal space.

In the present invention, "a rust preventive agent exists in the internal space" indicates that the rust preventive agent exists in the internal space at least in the form of a gas, and as such a rust preventive agent, a volatile rust preventive agent is used. is desirable.

The optical recording medium according to the present invention includes two recording media each including the recording layer formed by sputtering or the like on a glass or plastic substrate, with an internal space containing air or an inert gas interposed between the recording layers. It has an air sandwich structure in which the two faces face the internal space. A layer of SiO or the like can be provided between the substrate and the recording layer, serving as a moisture-proof layer and an anti-reflection layer. Furthermore, Al, Ti, Si, Cr are used as a protective layer on the gloss layer.
, Al2O3, TiO2, SiO, SiO2, or the like can be formed. A rust preventive agent is present in the internal space.

The volatile rust preventive agent sealed in the internal space includes dicyclohexyl ammonium nitrite, amine-based substances,
There are reaction products of dicyclohexylamine and octanoic acid. P. M. [Japanese industry (
), Ferroguard [Ronco Laboratories, Inc., USA]
It is commercially available as , Zelast [Taiyo Liquefied Gas Co., Ltd.], Killesguard [Nippon Kagaku Sangyo Co., Ltd.], etc.

The invention will be explained below with reference to the drawings. FIG. 2 is a schematic longitudinal sectional view showing an example of a disk-shaped photothermal magnetic recording medium according to the present invention. Reference numerals 1 and 1' denote glass substrates, on which recording magnetic layers 2 and 2 made of amorphous magnetic material are formed. Two such recording media, spacers 3, 3'
The magnetic layers are sandwiched so that the surfaces of each magnetic layer opposite to the surfaces in contact with the substrate face each other. At this time, a powdered volatile rust preventive agent 4 is sealed in the air layer 8 .

FIG. 3 is a schematic longitudinal section showing another example of the disk-shaped photothermal magnetic recording medium according to the present invention. In this example, plastic substrates 5 and 5' are used, and SiO layers 6 and 6' are formed between the recording magnetic layers 2 and 2' to serve as a moisture-proof layer and an antireflection layer, respectively.

In addition, two such recording media are connected to spacers 3 and 3'.
At the time of sandwiching, Ar gas is introduced between the internal chambers to form an Ar gas layer 9, and at the same time, a volatile rust preventive agent 4 is sealed.

FIG. 4 shows a disk-shaped photothermal magnetic recording medium according to the present invention.
FIG. 7 is a schematic cross-sectional view showing still another example.

In this example, the above-mentioned protective layers 7 and 7' are further provided on the magnetic layer in the example shown in FIG.

According to the present invention, by allowing air to exist in the internal space of a photothermal recording medium having an air sandwich structure, photothermal magnetic recording with excellent acidity and high reliability can be achieved without impairing magnetic properties during writing and erasing from the substrate side. Media provided. The corrosion resistance of this recording magnetic layer was further improved compared to the conventional one.

EXAMPLES The present invention will be specifically described below with reference to Examples.

Example 1 A disk-shaped photothermal magnetic recording medium having the structure shown in FIG. 2 was manufactured as follows. FdTbFeCo thin films were formed as recording magnetic layers 2, 2 on glass substrates 1, 1' using a high frequency sputtering device. When sandwiching the two recording media thus obtained with spacers 3 and 3' in between,
A disk-shaped photothermal magnetic recording medium having an air sandwich structure was obtained by enclosing 0.02 g of zincohexylammonium nitrite powder as a volatile rust preventive agent.

For comparison, a disk-shaped photothermal magnetic recording medium was prepared in the same manner as above except that no rust preventive agent was included.

These were placed in a constant temperature and humidity chamber at a temperature of 85° C. and a relative humidity of 85% to perform a corrosion test. The retention strength of the photothermal timing recording medium according to the present invention after 500 hours was 75% of the initial value, and that of the recording medium not according to the present invention was 40%. From this result, it is estimated that the corrosion resistance of the photothermal magnetic recording medium according to the present invention is approximately twice as high as that of a medium not according to the present invention.

Example 2 A disk-shaped photothermal magnetic recording medium having the structure shown in FIG.
Plastic substrates 5, 5' instead of glass substrates 1, 1'
SiO layers 6, 6' are deposited on the substrate by electron beam heating using a vacuum evaporation device, and then a recording magnetic layer is formed thereon, and an Ar gas layer 9 is provided in place of the air layer 8. Except for this, it was produced in the same manner as in Example 1.

For comparison, an on-disk photothermal magnetic recording medium was obtained in the same manner as above except that no volatile rust inhibitor was present.

This was subjected to a corrosion test in the same manner as in Example 1, and as a result, the retention strength after 500 hours was 72% and 35% of the initial value, respectively. These results revealed that the corrosion resistance of the magneto-optical recording medium according to the present invention was improved to about twice that of a medium not according to the present invention.

Example 3 A disk-shaped photothermal magnetic recording medium having the structure shown in FIG.
, 7' were produced in the same manner as in Example 2, except that an Al film was vacuum-deposited.

For comparison, a disk-shaped photothermal magnetic recording medium was produced in the same manner as above except that no volatile rust inhibitor was present.

When these were subjected to a corrosion test in the same manner as in Example 1, it was found that the corrosion resistance of the photothermal magnetic recording medium according to the present invention was about 10% superior to that of a medium not according to the present invention.

As is clear from these Examples, Examples 1 and 2
Since the protective film is not formed by vapor deposition, equipment such as a vacuum vapor deposition machine is not required, and the product can be manufactured in a short time and at low cost.

Furthermore, the corrosion resistance, especially that of Example 2, is comparable to that with the protective layer shown in FIG.

In the above example, an example of installing a rust preventive agent was schematically shown, but
In practice, it is possible to partition the internal space with partition plates having ventilation holes, and, for example, to encapsulate a rust preventive agent in the center of the substrate.

As explained above, the present invention is particularly suitable for use in recording media with non-quality magnetic films, but is not limited thereto, and is also applicable to other photothermal magnetic recording media or other optical recording media using Te, TeOx, etc. as the recording layer. Even when applied to commercial recording media, it is sufficiently effective in improving corrosion resistance.

[Brief explanation of the drawing]

FIG. 1 is a schematic longitudinal cross-sectional view showing an example of a conventional disk-shaped photothermal magnetic recording medium, and FIGS. 2 to 4 are schematic longitudinal cross-sectional views showing an example of a disk-shaped photothermal magnetic recording medium according to the present invention. It is a front view. 1, 1'... Glass substrate 2, 2'... Recording magnetic layer 3, 3'... Spacer 4... Volatile rust preventive agent 5, 5'... Plastic substrate 6, 6'... ...SiO layer 7, 7'...protective layer 8...air layer 9...Ar gas layer

Claims (1)

[Claims] 1. Two recording media including a recording layer formed on a substrate are sandwiched between them with an internal space containing air or an inert gas,
1. An optical recording medium having a sandwich structure in which the recording layers are opposed to each other so as to face an inner space, wherein a rust preventive agent is present in the inner space.