JPS6159647A - Optical recording medium - Google Patents

Abstract

PURPOSE:To prevent the deterioration of a recording layer owing to the intrusion of external air from a substrate side and to obtain a photomagnetic memory, etc. having good durability by incorporating itself or the auxiliary layer on the substrate and providing a magnetic recording layer thereon. CONSTITUTION:The org. inhibitor such as benzotriazole or the inorg. inhibitor such as nitrous acid, polyphosphate or the basic buffer effect material of silicic acid of >=7pH, inorg. weakly acidic alkaline salt of phosphoric acid, etc., hexyl amine or arom. amine, etc. is incorporated into the substrate 1 itself or is incorporated into the auxiliary layer 2 in common use as a casting mold layer for forming guide grooves on the substrate 1. The layer 2 is obtd. by placing the substrate on a radiation curing resin incorporated with the above-described inhibitor or buffer material in a metallic mold 8, irradiating UV rays 9 from an arrow direction on the substrate to cure the resin and utilizing the same to the substrate 1. A protective layer 3, an optical recording (TbFe, etc.) 4, a dielectric layer 5, a reflecting layer 6 and further a protective layer 7, etc. are provided on the layer 2. The corrosion resistance of the recording layer is thus improved and the photomagnetic recording medium, etc. having the excellent durability are obtd.

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention is used in magneto-optical memories, RA recording, display elements, etc., and records data using optical effects such as the magnetic Kerr effect or the Faraday effect. This invention relates to improving the corrosion resistance of recording media such as magneto-optical recording media from which information can be read.

[Conventional technology]

Conventionally, as magneto-optical recording media, nBi, MnGu
Polycrystalline 9 films such as Bi, GdC:o, GdFe, T
bFe, DyFe.

GdTbFe, TbDyFe, GdFeCa, T
amorphous thin films such as bFeCa, GdTb1ll;o,
Single crystal thin films such as TbFeO3 are known.

Among these thin films, the film formation efficiency when producing a large-area thin film at a temperature near room temperature, the writing efficiency of writing signals with small photothermal energy, and the ability to read written signals with a good S/N ratio are important. Considering read efficiency and the like, the amorphous thin film is recently considered to be excellent for use in photothermal magnetic recording media. In particular, GdTbFe has a large Kerr rotation angle and a single Curie point of around 150° C., making it optimal for photothermal magnetic recording media. Furthermore, as a result of our research aimed at improving the Kerr rotation angle, we found that
GdTbFeCo has a sufficiently large Kerr rotation angle and S/N
We have discovered that this is a photothermal magnetic recording medium that can be read with a high ratio.

However, amorphous magnetic materials such as GdTbFe generally have poor corrosion resistance, and have the disadvantage 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 of an amorphous magnetic material, or to create an air sandwich structure or a bonded structure in which the recording magnetic layer is sealed with an inert gas. Disk-shaped photothermal magnetic recording media have been proposed.

[Problem that the invention seeks to solve]

However, these magneto-optical recording media are not fully satisfactory in terms of corrosion prevention effect and cost. That is, when providing a protective layer, it is difficult to eliminate moisture permeability and oxygen permeability if the protective layer is an inexpensive organic coating layer, and if the protective layer is an inorganic coating layer,
In addition to being expensive, pinholes may occur and the corrosion prevention effect may not be sufficiently achieved.

The inert gas is sealed and the magnetic recording layer is air sealed.
Even in the case of a square structure, the cost is high and there are problems such as the flatness of the medium changes due to fluctuations in external pressure. Furthermore, even when corrosion protection is improved by a laminated structure, there is a possibility that moisture and oxygen may permeate through the laminated interface or the adhesive layer of the laminated structure. Furthermore, when plastics are bonded together to form a bonded structure, the plastic plates themselves do not have sufficient moisture and oxygen permeation prevention properties.

The present invention has been made in order to solve one or more problems, and an object of the present invention is to provide a magneto-optical recording medium that is low in cost and can sufficiently prevent corrosion due to oxygen and moisture. .

Means for Solving Problem C] The magneto-optical recording medium of the present invention is an optical recording medium having at least a magnetic recording layer on a substrate. The auxiliary layer is characterized in that it contains an inhibitor and/or a basic buffering substance.

[Preferred mode for carrying out the invention]

In one embodiment of the optical recording medium of the present invention, the substrate contains an inhibitor or a basic buffering substance. As the material constituting the substrate, conventionally known materials such as glass, acrylic resin, polycarbonate, polyethylene, polyimide, etc. can be used.

Inhibitors to be included in the substrate include commonly known organic inhibitors such as hexamethylenetetramine, benzotriazole, dicyclohexylammonium nitride, quinoline, 1,000 urea, propyl sulfide, chromium salt resistance, nitrite salt resistance, and polyphosphoric acid. Inorganic inhibitors such as salts, phosphates, molybdates, etc. can be used.

The 1iX-based buffering substance referred to in the present invention is a substance that creates an environment with a pH of 7 or more through its buffering action, and particularly preferably a substance that makes the pH 9 or more. For example, alkali metal J42 such as sodium salts and potassium salts of inorganic weak acids such as silicic acid, borium, phosphoric acid, carbonic acid, and polyphosphoric acid; aliphatic amines such as ethylamine, butylamine, hexylamine, and isopropylamine; Alicyclic 7-amines represented by propylamine; aromatic amines represented by dimethylaniline; trisaminomethane and 2-amino-
Amine compounds such as 2-methyl-1,3-propanediol and other basic compounds such as 2,4,8-trimethylpyridine and sodium dimethylglycine can be used.

The magnetic recording layer of the optical recording medium is preferably formed of an amorphous magnetic thin film for the purpose of the present invention.
, MnCuB1, etc. may be a conventionally known thin film having a magneto-optic effect, such as a polycrystalline thin film such as MnCuB1.

To form a substrate containing an inhibitor or a basic buffering substance using the above materials.

It can be produced by molding a substrate material to which an inhibitor or the like is added into a predetermined shape by injection molding or the like.

The amount of inhibitor or basic buffering substance added varies depending on the order of addition and the material of the substrate, but in general, it is 0% to the substrate.
．． 01 to 10i amount % is preferable.

A more preferable addition amount is about 0.5 to 3 times, j-1% if the inhibitor or basic buffering substance is an organic substance, and about 0.1 to 1 wt% if it is an inorganic substance.

It is preferable to provide a pre-groove on this substrate for accurate recording Φ reproduction. To provide the pre-groove,
For example, the substrate may be injection molded using a predetermined mold.

Further, this optical recording medium may be provided with various other layers such as a protective layer for protecting the magnetic recording layer and a reflective layer for effectively utilizing recording light and reproducing light.

Another embodiment of the optical recording medium of the present invention has a structure in which an auxiliary layer containing an inhibitor and/or a basic buffering substance is provided between the substrate and the magnetic recording layer.

In this optical recording medium as well, the substrate and the magnetic recording layer can be formed using the same conventionally known materials as in the optical recording medium described above.

The auxiliary layer may contain substances with film-forming ability, such as inhibitors and/or basic HH in various coating materials.
j is a layer formed by containing an active substance.

Examples of coating agents having film-forming ability include:
Organic or inorganic coating agents such as a room temperature drying type, a room temperature curing type, a heat drying type, a heat curing type, a photocuring type, an electron beam curing type, and a hot melt type can be used.

As the inhibitor and 142-based buffering substance, those similar to those in the above embodiment can be used.

To form the auxiliary layer, an inhibitor or a basic buffering substance is added to a substance capable of forming a film, dispersed or dissolved, and then added to the substrate or the auxiliary layer provided between the substrate and the magnetic recording layer. It can be formed by coating and curing. The amount of the inhibitor or basic buffering substance to be added varies depending on the type thereof and the type of substance having film-forming ability, but it is usually the same amount as when it is contained in the substrate.

The thickness of the auxiliary layer varies depending on the thickness of the magnetic recording layer, but is usually about 10 to 200 μs.

Also in the optical recording medium of this embodiment, various layers such as a protective layer and a reflective layer can be provided as the a layer.

It is desirable that the auxiliary layer also serve as a mold layer for forming guide grooves provided in the magnetic recording layer for accurate recording and reproduction. The magnetic recording layer has an uneven pattern corresponding to the guide groove of the magnetic recording layer, and the magnetic recording layer is coated directly or through another layer having a uniform thickness on this pattern so as to have a uniform thickness. A layer for providing guide grooves in a magnetic recording layer.

A schematic cross-sectional view of an embodiment of an optical recording medium having an auxiliary layer overlaid with a template layer is shown in FIG.

1 is a substrate, and 2 is an auxiliary layer that also serves as a mold layer.

The auxiliary layer 2, which also serves as the M-type layer, can be formed by applying a method similar to the conventional method of forming a simple mold layer that does not have a corrosion-preventing effect, but a typical example of this forming method is shown in Fig. 2. I will briefly explain. Auxiliary layer 2 that also serves as a Vj type layer in this example
describes the formation method when the substance having film-forming ability is a photocurable resin, but it can be formed by almost the same method when electron beam curable resin, heat curable resin, etc. are used as the substance. .

First, an inhibitor and/or a basic agent is added to a monomer or prepolymer of a photocurable polymer (a photocuring initiator is also added if necessary) and mixed, and this mixture is formed into a predetermined shape. The mold 8 is filled and the substrate 1 is placed on top of the mold 8. Next, light 9 that almost passes through the substrate 1 and is capable of polymerizing and curing the photocurable polymer or prepolymer is emitted from the substrate side. Irradiate to cure the monomer or prepolymer. After that, gold 2! ! By removing 8, an auxiliary layer 2 which also serves as a mold layer can be formed.

3 and 7 are protective layers for protecting this optical recording medium. These protective layers are TiO2, /u2
It is formed by forming 03, 5i02, Grzo3, etc. into a uniform thickness by various steaming methods.

4 is a magnetic recording layer, which has the above-mentioned magneto-optical effect and is coated with a uniform thickness by various thinning methods.
+q. In this magnetic recording layer 4, guide grooves corresponding to the pattern of the auxiliary layer 2, which also serves as a template layer, are easily formed by the above-mentioned vapor deposition method, etc., and accurate recording and reproduction are possible.

5 is a dielectric layer, and 6 is a reflective layer.0 During recording, the recording light that has passed through the magnetic recording layer 2 is irradiated onto the magnetic recording layer 2 again by the reflective layer 5, so that the energy of the recording light becomes effective. Available. Further, during reproduction, a part of the reproduction light transmitted through the magnetic recording layer 2 is multiple-reflected between the dielectric layer and the reflective layer 5.

By simultaneously detecting this light and a portion of the reproduction light reflected by the magnetic recording layer 2, the reproduction efficiency can be increased.

The dielectric layer 5 is 5i02, Si3\, etc., and the reflective layer 6 is M
.

Cu, Ni, Cr, Ti, etc. can be formed by various vapor deposition methods.

The protective layers 3 and 7, the dielectric layer 5, and the reflective layer 6 may be omitted depending on the required durability, recording efficiency, and reproduction efficiency of this optical recording medium.

The substrate or auxiliary layer containing the inhibitor and/or basic buffering substance is GdTbFeGo, GdTbF.
eGdCo, GdFe, TbFe, DyFe,
Corrosion resistance can be improved not only when applied to optical magnetic recording media such as TbAD7Fe, but also to recording media having recording layers made of tellurium oxide, tellurium carbide, etc.

〔Effect of the invention〕

The optical recording medium of the present invention makes it possible to easily improve corrosion resistance against oxygen, moisture, etc., compared to conventional optical recording media. Furthermore, since the auxiliary layer can be formed as a substrate and a mold layer without forming it separately, it can be manufactured at low cost and without increasing the number of manufacturing steps.

〔Example〕

Hereinafter, the present invention will be explained in more detail based on examples.

Example 1 First, 2% by weight of benzoin isopropyl ether as a photocuring initiator and 0.2% by weight of hexamethylenetetramine as an inhibitor were added to ethylene gelcol dimethacrylate, which is a hexamer of a photocuring polymer. The mixture is filled into a mold of a predetermined shape, and an acrylic resin substrate is placed on top of it. Ultraviolet light is irradiated from the substrate side to harden the 7-summer, and then The mold was removed and an auxiliary layer that also served as a mold layer with a layer thickness of 70 μ was formed.
Next, on the auxiliary layer that also serves as the template layer, by vacuum deposition method,
A protective layer of SiO with a thickness of 1000 A was formed, and an amorphous, G
A magnetic R layer 4 of dTbFeCa was formed in H9.

Next, on top of this, a single layer of 200 OA thick S
iO dielectric layer 51 layer thickness tooA Cu reflective layer 6;
A protective layer 7 of SiO with a thickness of 200 OA was sequentially formed.

An optical recording medium was produced.

This optical recording medium was left at 45° C. and 95% relative humidity for 250 hours to measure changes in coercive force and conduct a corrosion resistance test. The results are shown in Table 1.

Examples 2 to 10 Each was carried out in the same manner as in Example 1, except that the inhibitor or basic buffering substance shown in Table 1 was added in the amount shown in Table 1 instead of the inhibitor hexamethylenetetramine added in Example 1. An optical recording medium was produced and a corrosion resistance test was conducted. The results are shown in Table 1.

Comparative Example 1 An optical recording medium was prepared in exactly the same manner as in Example 1 except that the inhibitor hexamethylenetetramine was not added, and the results of a corrosion resistance test are shown in Table 1.

Example 11.12 Optical recording media were prepared in the same manner as in Examples 1 and 3, except that the substrate used in Examples 1 and 3 was changed from acrylic resin to a glass plate, and a corrosion resistance test was conducted. Ta. The results are shown in Table 2.

Comparative Example 2 An optical recording medium was prepared in the same manner as Comparative Example 1 except that the acrylic resin substrate used in Comparative Example 1 was replaced with a glass substrate, and a corrosion test was conducted.

The results are shown in Table 2.

As is clear from Tables 1 and 2, the optical recording medium of the present invention having an auxiliary layer containing an inhibitor or a basic buffering substance has better corrosion resistance than the conventional one.

Table 1 Table 2

[Brief explanation of drawings]

Fig. 1 is a schematic cross-sectional view showing an example of the optical recording medium of Fig. 1, and Fig. 2 is a schematic view showing the process of forming an auxiliary layer which also serves as a Pi type layer. Auxiliary layer 3.7: protective layer 4: magnetic recording layer 5: dielectric layer 6: reflective layer 8: dielectric layer 9
:Light = :pH diagram Figure 2

Claims (1)

Claims: 1) An optical recording medium having at least a magnetic recording layer on a substrate, wherein the substrate or an auxiliary layer disposed between the substrate and the magnetic recording layer contains an inhibitor and/or an auxiliary layer disposed between the substrate and the magnetic recording layer.
Or an optical recording medium characterized by containing a basic buffering substance. 2) The optical recording medium according to claim 1, wherein the auxiliary layer also serves as a template layer for forming guide grooves of the magnetic recording layer.