JPS62173657A - Photomagnetic recording medium - Google Patents

Abstract

PURPOSE:To manufacture the titled medium at an ordinary temp. without spoiling the characteristics of photomagnetic recording layers and to form the medium having a good shelf life and low cost by joining the media formed by providing the photomagnetic recording layers to substrates to each other by an adhesive agent consisting of a one-component wet curing type polyurethane. CONSTITUTION:This medium is formed by joining two pieces of the media 15 each formed by laminating the photomagnetic recording layer 13 and dielectric films 12 and 14 on a substrate 1 to each other by the adhesive agent 6 consisting of the one-compoent wet curing type polyurethane. The thicknesses of the respective layers are preferably such that the photomagnetic recording layer 13 is formed to 1,000-1,500Angstrom and the dielectric films 12, 14 are formed to 300-600Angstrom . The protection of the underlying layers is executed if a UV-curing resin is preliminarily coated on the respective layers and is cured prior to joining.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to a magneto-optical recording medium, particularly a magneto-optical storage element.

Prior Art Optical disks are characterized by high density, large capacity, and high speed access, and various research and development efforts are being conducted on them.

Currently commercially available playback-only optical discs use a hot-melt adhesive to bond two substrates with A1 reflective films, as disclosed in Japanese Patent Application Laid-open No. 58-6536, and playback from both sides is possible. making it possible. In a disk in which information is recorded by making minute holes (pits) in the recording film using a laser beam, as shown in FIG. 2, spacers 2. 3
It has an air sand inch structure in which the parts are sandwiched in between and joined only at that part. In this case, the adhesive 6 used to bond both substrates 4.5 and spacer 2.3 is a thermosetting epoxy adhesive or an ultraviolet curing adhesive.

In addition to this, it is also possible to use a two-component room temperature curing epoxy adhesive.

On the other hand, as a type of rewritable optical recording, magneto-optical recording using a laser is attracting attention.

Magneto-optical recording media, such as optical discs, are made of Sm, Eu, Gd5Tb, etc. on a transparent substrate made of glass or plastic.
, , Dy, HOlEr and other rare earths, as well as Fe, Co, N
There is one in which a magnetic alloy film with a transition metal such as i is formed in an amorphous form by means such as sputtering or vapor deposition, and further coated with an organic protective film to provide scratch resistance.

However, such magneto-optical recording media have Q
Materials such as d, Tb, and Fe are used, and when the recording layers are bonded to each other with the hot melt adhesive described above, they are easily corroded by the hot melt adhesive. Therefore, these cannot be used for magneto-optical applications.

Magneto-optical disks do not require the air sandwich described above (the hole-punched type requires a hollow section 7 as shown in Figure 2 to evaporate the recording film), so full-surface bonding is preferred due to cost considerations. It takes shape. In this case, since the recording layer hardly transmits ultraviolet rays, an ultraviolet curing adhesive cannot be used to bond the substrates on which the recording layers are attached.

In addition, when using epoxy adhesive as an adhesive, process control is complicated for the two-component heating type, and the curing agent itself is
It corrodes d'PTb and Fe (therefore, if there is poor mixing when mixing the two liquids, it will cause film corrosion). 1
In the liquid heat curing type, it is difficult to use plastic for the substrate due to thermal deformation, it is difficult to avoid thermal deterioration of the recording film, and a curing furnace is required, which increases production costs. Room-temperature curing epoxy takes too long to cure, resulting in poor productivity.

Furthermore, polyurethane-based adhesives can be considered, but there are two-component types that are cured by oxygen in the atmosphere and those that are cured by heating, and two-component types that are cured with amine catalysts and others. , some are cured by reaction with polyol compounds. However, materials that harden with oxygen do not harden when fully bonded,
Thermosetting materials cannot be used for the reasons mentioned above. In catalytic curing,
Amine-based catalysts also corrode the magnetic layer.

OBJECT OF THE INVENTION An object of the present invention is to provide a low-cost medium that can be manufactured at room temperature without impairing the characteristics of the magneto-optical recording layer, has good storage stability, and is low in cost.

22 Structure of the invention and its effects, that is, the present invention particularly provides for a medium in which a support is provided with a magneto-optical recording layer capable of recording, reproducing or erasing information using a laser beam and having at least a magneto-optic effect. These relate to magneto-optical recording media formed by bonding them together using a one-component moisture-curing polyurethane adhesive.

According to the present invention, a one-component moisture-curing polyurethane adhesive (hereinafter referred to as the adhesive of the present invention) is used to bond the media (specifically, the sides with the magneto-optical recording layer). Therefore, adhesion can be performed simply at room temperature, and corrosion of the component metals of the recording layer does not occur at that time.

A suitable adhesive of the present invention is produced by reacting a compound having a plurality of isocyanate groups in the molecule with a compound having a plurality of hydroxyl groups in an excess of isocyanate, as described below, to form an isocyanate group at the end of the molecule. This method uses a polyisocyanate that has been adjusted to have a plurality of .

(n+1)OCN-R-NCO+nHO-R-OHThe curing mechanism is as follows.

NCO ~~-R-NHCNH-R~4 The polyisocyanates used here include aromatic ones such as toluene diisocyanate and diphenylmethane diisocyanate, and aliphatic ones such as hexamethylene diisocyanate.

As the polyol, 1,4-butanediol, 1.5
-bentanediol, polyether glycol, etc. are used.

Specific examples of this polyurethane include Imron manufactured by DuPont and Mondor E-152 manufactured by Mobay Chemical Company.
, Coronate 2013 manufactured by Nippon Polyurethane Co., Ltd., and the like.

The magneto-optical recording layer has an axis of easy magnetization perpendicular to the film surface, can record, reproduce, or erase information with a light beam, and is made of a known material such as Tb.
It can be composed of a rare earth-transition metal amorphous alloy such as Fe5GdFe, GdTbFeCo, and GdCo. Sputtering, as is well known, may be used for forming the film.

Further, a dielectric film may be provided on the magneto-optical recording layer, and such a dielectric film may include Si 3 N 4
Including AIN, 5i02, Z n S %I To
(Indium Tin Oxide) and the like. This dielectric film can be laminated on the magneto-optical recording layer by sputtering, but it can also be provided between the magneto-optical recording layer and the substrate and the magneto-optical recording layer is sandwiched between dielectric films. good. This sandwich structure makes it difficult for oxygen to be taken in from the substrate during film formation, which tends to occur when a resin substrate is used as the substrate.
It is considered advantageous.

Various materials can be used for the substrate, including plastics such as polyethylene terephthalate, polyvinyl chloride, cellulose triacetate, polycarbonate, polyimide, polyamide, and polymethyl methacrylate. Substrates made of glass, ceramics, etc. can also be used. The shape of the substrate or base body may be a sheet, a card, a disk, a drum, or a long tape.

FIG. 1 shows a magneto-optical recording layer 13 and a dielectric film 12 on a substrate 1.
This shows an example of a magneto-optical recording medium according to the present invention, in which two media 15 in which media 15 and 14 are laminated are bonded to each other with an adhesive 16 made of the above-mentioned one-component moisture-curing polyurethane. . Here, the thickness of each layer is 1,000 to 1,500 for the magneto-optical recording layer 13 and 1,000 to 1,500 for the dielectric film 12.
14 is preferably 300 to 600 people.

Note that, if an ultraviolet curing resin is applied on each recording layer and cured before the above bonding, the underlying layer can be protected.

E, Example Hereinafter, the present invention will be explained in more detail with reference to Examples.

Example 31 - Si 3 N 4 film, GdTbF on a φ120 polycarbonate substrate (with guide grooves at a pitch of 1.6 μm)
The E film and the S i 3 N 4 film were formed by sputtering in the order of 1000 people each, and a protective coating layer of ultraviolet curable resin was further applied thereon using a spin cord.

Two sheets of this were prepared, and after being pasted together with liquid moisture-curing polyurethane adhesive cloth (IMURON), they were heated at 60°C and 80°C.
%RH environment for one month. When we measured the bit error rate of the signal before and after that, we found that it ranged from 2 x 10-6 to lXl
It had changed to 0-5. Note that the adhesive was applied by screen printing.

When a recording film was provided in the same manner as above and a protective film was attached, and the film was kept at 60° C. and 80% RH, the bit error rate changed from 2XIO-6 to 3X10-5.

Comparison Plate I In Example 1, when the adhesive was a hot melt adhesive (HM40B manufactured by Cemedine) and kept for one month at <60°C and 80% RH, the bit error rate was 2 x 10-6 to 3 x 10. It had changed to -3.

In Example 1, the adhesive was applied by screen printing and bonded together without providing a protective film. When the bit error rate was measured immediately after bonding, it was 1×10 4 .

In the above results, in comparison with Comparative Example 1, in Example 1,
Since the recording film is sandwiched between two substrates by adhesion, environmental resistance is further improved.

In Comparative Example 2, the corrosive components in the adhesive penetrated into the protective film and corroded the recording film, resulting in a significant deterioration in the bit error rate.

In the reference example, the bit error rate increased because the recording film was damaged when applying the adhesive.

Although the present invention has been illustrated above, the above-mentioned example can be further modified based on the technical idea of the present invention.

[Brief explanation of drawings]

FIG. 1 is an enlarged sectional view of a portion of a magneto-optical recording medium according to an embodiment of the present invention, and FIG. 2 is a sectional view of a conventional optical disk having an air sand inch structure. In addition, in the symbols shown in the drawings, 1...... Substrate 12. 14... Dielectric film 13...
. . . Magneto-optical recording layer 5 . . . Medium 6 . . . Adhesive.

Claims (1)

[Claims] 1. A magneto-optical recording medium formed by bonding media each having a magneto-optical recording layer on a support using a one-component moisture-curing polyurethane adhesive.