JP2613082B2 - Magneto-optical recording element - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magneto-optical recording element having two types of substrates and a magneto-optical recording element formed by bonding two types of magneto-optical recording members.

[Prior art and its problems]

Recently, high-density magneto-optical recording using an amorphous metal alloy composed of a rare-earth metal and a transition metal has been actively studied, and the recording method is to locally emit a focused laser beam by projecting a focused laser beam onto a recording medium, As a result, the bits are written and then read using the magneto-optical effect, and the recording bits can be erased and the bits can be written again.

In such a magneto-optical recording method, as shown in FIG. 4, two types of magneto-optical recording members can be bonded together via an adhesive resin layer, so that the degree of utilization of the magneto-optical recording can be significantly increased.

In the figure, a magneto-optical recording member A is formed by sequentially laminating a magnetic layer 2a and an ultraviolet-curable protective resin layer 3a on a substrate 1a, while a magnetic layer 2b, A magneto-optical recording member B is formed by sequentially laminating an ultraviolet curing type protective resin layer 3b, and both recording members A and B are bonded together via an adhesive resin layer 4. In such a magneto-optical recording element, recording, reproduction, and rewriting can be performed by projecting a focused laser beam from the substrate 1a or the substrate 1b.

For the adhesive resin layer 4 used in the magneto-optical recording element having the above-mentioned configuration, an ultraviolet curable resin or a resin adhesive such as an epoxy-based, acrylic-based, urethane-based, or cyanoacrylate-based resin is used.

However, when these resins are applied onto the UV-curable protective resin layers 3a, 3b and then cured, the resin layer 4 contracts with the curing, and the resin layer 4 and the protective resin layers 3a, 3b Stress distortion occurs in the magnetic layer 2a,
Stress corrosion occurs in 2b, and as a result, the magneto-optical recording characteristics deteriorate over time. Further, when substrates 1a and 1b having birefringence are used for the magneto-optical recording element, the birefringence increases due to the stress, and as a result, the initial characteristics of magneto-optical recording deteriorate.

When the hot melt type adhesive made of a thermoplastic resin is used for the resin layer 4, the above problem is solved. On the other hand, the adhesive softens and flows under a high temperature environment,
Therefore, the adhesive performance is remarkably inferior.

The adhesive resin layer 4 is preferably made of a resin that does not corrode the magnetic layers 2a and 2b and that does not chemically degrade the substrates 1a and 1b. It is not spoiled.

[Object of the invention]

Accordingly, the present invention has been completed in view of the above circumstances, and an object of the present invention is to eliminate stress distortion in a magneto-optical recording member, thereby obtaining excellent magneto-optical recording characteristics and maintaining the initial characteristics. An object of the present invention is to provide a magnetic recording element.

Another object of the present invention is to provide a high-quality and high-reliability magneto-optical recording element in which a resin adhesive used for a magneto-optical recording element does not attack a magnetic layer or a substrate.

[Means for solving the problem]

According to the present invention, in a magneto-optical recording element in which at least a magnetic layer, an adhesive resin layer, and a second substrate are sequentially formed on a first plastic substrate, the adhesive resin layer is made of a non-alcohol type silicone resin. And elastic modulus is 1.5
Provided is a magneto-optical recording element characterized by being set to × 10 ⁷ dyn / cm ² or less.

According to the invention, a first magneto-optical recording member having at least a magnetic layer formed on a plastic substrate, a second magneto-optical recording member having at least a magnetic layer formed on a plastic substrate, and The first magneto-optical recording member and the second
In a magneto-optical recording element comprising an adhesive resin layer for bonding a magneto-optical recording member, the adhesive resin layer is made of a dealcohol-type silicone resin and has an elastic modulus of 1.5.
Provided is a magneto-optical recording element characterized by being set to × 10 ⁷ dyn / cm ² or less.

 Hereinafter, the present invention will be described in detail.

FIG. 1 shows the individual magneto-optical recording members of the magneto-optical recording element of the present invention, and FIG. 2 shows the basic layer structure when the magneto-optical recording members are bonded.

According to FIG. 1, a magneto-optical recording member c is formed by forming a magnetic layer 2c on a plastic substrate 1c.
On the other hand, a magneto-optical recording member D having a magnetic layer 2d formed on a plastic substrate 1d is also manufactured.

Next, an adhesive resin 5 is applied to at least one of the magnetic layers 2c and 2d, and is naturally cured at room temperature or cured by heating to obtain a magneto-optical recording element as shown in FIG.

In the present invention, the adhesive resin layer 5 is formed of a dealcohol-type silicone resin, and the elastic modulus is set within a predetermined range. Stress corrosion does not occur in the layers 2c and 2d.

The dealcohol-type silicone resin is a type of condensation-type silicone resin, and the condensation-type silicone resin is cured by a hydrolytic condensation reaction between silanol, which is a main component, and a cross-linking agent. , Acetoxysilane, enoxysilane and the like can be used to produce condensation by-products such as alcohol, acetic acid and ketone. Therefore, they are classified into dealcohol type silicone resin, deacetic acid type silicone resin, deacetone type silicone resin and the like according to the type of condensation by-product.

As a result of repeating various experiments, the present inventors selected a dealcoholated silicone resin from the above condensation type silicone resins, and when this was used for the adhesive resin layer 5, the magnetic layer 2c, It has been found that it does not corrode 2d or attack the substrates 1c and 1d.

That is, when a deacetic acid type silicone resin is used, the magnetic layers 2c and 2d are corroded, and for the deacetone type silicone resin, the substrates 1c and 1d, particularly the polycarbonate resin substrate and the acrylic resin substrate are eroded. I found something.

Further, in using the dealcoholized silicone resin, the elastic modulus is set within a predetermined range by changing the type of the organic group R in the molecular structure, the degree of polymerization, and the crosslink density.

The elastic modulus is 1.5 × 10 ⁷ dyn / cm ² or less, preferably 1.0 × 10
^When it is set to ⁷ dyn / cm ² or less, the stress generated at the interface between the bonding resin layer 5 and the magnetic layers 2c and 2d is reduced, and there is no stress corrosion, and the birefringence of the plastic substrates 1c and 1d. No adverse effects such as an increase in

The magnetic layers 2c and 2d are amorphous metal perpendicular magnetization films having an easy axis of magnetization in a direction perpendicular to the film surface.
There are thin films made of rare earth-transition metal alloys such as dCo, TbFeCo, GdDyFe, DyFeCo, GdTbFeCo, and GdDyFeCo.

A plastic plate is used for the substrates 1c and 1d, and examples of the material for the plastic substrate include a polycarbonate resin, an epoxy resin, a polyester resin, and an acrylic resin.

Further, in the magneto-optical recording element of the present invention, the substrates 1c and 1d
A dielectric layer may be formed between the magnetic layer and the magnetic layers 2c and 2d, and when a laser beam is projected from the substrate side, the apparent Kerr rotation angle is increased by the enhancement effect, thereby increasing the performance index. Can be.

This dielectric layer is made of Sialon, SiN, AlN, SiC, CdS, TiC, TiC
It is formed of a material such as N, ZnS, MgF ₂ , Al ₂ O ₃ , CeO ₂ , ZrO ₂ , SiO, SiO ₂ , CdO, Bi ₂ O ₃ .

Further, between the magnetic layers 2c and 2d and the resin layer 5, the above-mentioned dielectric layer material or a corrosion-resistant metal such as Ti, Cr, Zr, Ta, or Al, or an oxide, nitride, carbide, or sulfide thereof. A non-magnetic layer composed of a single compound or a combination of compounds may be formed.

Furthermore, between the magnetic layers 2c and 2d and the resin layer 5, or between the non-magnetic layer and the resin layer 5 formed on the magnetic layers 2c and 2d.
An ultraviolet-curable resin layer may be formed between them, whereby the reliability of the magneto-optical recording element itself can be further improved.

Thus, according to the magneto-optical recording element having the above structure, no stress distortion occurs in the bonding resin layer 5, and the magnetic layers 2c, 2d
As a result, the substrates 1c and 1d are not chemically attacked. As a result, excellent magneto-optical recording characteristics are obtained, and the initial characteristics of magneto-optical recording are maintained.

Further, according to the present invention, a similar effect can be obtained for a magneto-optical recording element having two types of substrates as shown in FIG.

In the drawing, a magnetic layer 7 is formed on a substrate 6, a protective substrate 8 is prepared, an adhesive resin is applied on the substrate 8, and the substrate 8 is When bonding is performed via a resin and then natural curing at room temperature or curing by heating, an adhesive resin layer 9 is formed, and thus a magneto-optical recording element as shown in FIG. 3 is obtained.

For such a protective substrate 8, a plastic plate or a glass plate similar to the substrate 6 can be used.

〔Example〕

 Next, examples of the present invention will be described.

Using an AC three-source magnetron sputtering apparatus, a dielectric layer (a layer containing silicon nitride as a main component and containing Y atoms, Al atoms, and O atoms in a polycarbonate disk substrate, which is a so-called YSiAION layer / ..A layer called an yttrium sialon layer) having a thickness of 725 mm, and a GdDyFe perpendicular magnetization film having a thickness of 300 mm was formed on this layer.
Then, a titanium oxide layer (having a ratio of oxygen atoms to titanium atoms set in the range of 0.05 to 0.90) is formed in the same device to have a thickness of 650 mm. A UV-curable resin was applied on the titanium oxide layer by spin coating to form a resin layer, thereby producing a magneto-optical recording member.

Next, two such magneto-optical recording members were prepared, and an adhesive resin as shown in Table 1 was applied on the ultraviolet curable resin layer of one of the magneto-optical recording members. The two members were adhered to each other via.

The six types of magneto-optical recording elements thus obtained (No. 1 to N
With regard to o.6), the distribution of birefringence over the entire surface of the substrate was examined using a polarizing microscope, and the results A shown in Table 1 were obtained.

In the result A, the mark ○ indicates a case where uniform birefringence was obtained over the entire substrate surface, the mark x indicates a case where abnormal birefringence was recognized in part of the substrate surface, and the mark △ indicates a case where abnormal birefringence was observed. This shows a case where slightly abnormal birefringence is observed in a part of the surface.

In addition, each magneto-optical recording element was placed under high temperature and high humidity (75 ° C, 85 ° C).
% RH) for 500 hours, and the state of corrosion of the magnetic layer was examined. As a result, B was obtained.

In the result B, the mark ○ indicates the case where corrosion did not occur, the mark 場合 indicates the case where corrosion was remarkable, and the mark △ indicates the case where slight corrosion was observed.

Further, for each magneto-optical recording element, the state of deterioration of the substrate, that is, the state of occurrence of discoloration and cracks due to dissolution and decomposition of the substrate was examined, and the result C was obtained.

In the result C, the mark ○ indicates the case where no abnormality was recognized on the substrate, and the mark × indicates the case where discoloration or crack was recognized.

As is evident from Table 1, element No. 6 exhibited uniform birefringence over the entire substrate surface, did not cause corrosion on the magnetic layer, and showed no abnormality in the polycarbonate substrate itself. Did not occur.

Next, among the above magneto-optical recording elements, (i)... Element 6 (ii)... Element 5 (iii)... Element 3 (iv). ℃, 85% RH)
When the change with time of the error rate was followed, the result as shown in FIG. 5 was obtained.

In the figure, the horizontal axis is the idle time, the vertical axis is the ratio of the bit error rate BET (T) after the idle to the bit error rate BER (O) at the start of the idle, and
○ mark, ● mark, △ mark and ▲ mark indicate the above (i), (i
It is a plot corresponding to i), (iii) and (iv), and the display of the characteristic curve in the figure is (i) (ii)
(Iii) Corresponds to (iv).

As is clear from FIG. 5, the element 6 of the present invention can obtain excellent magneto-optical recording characteristics over a long period of time.

In addition, the present inventors have found that when a deacetic acid-type silicone resin is used as the bonding resin, the magnetic layer is significantly corroded, and the bit error rate is deteriorated with time. As inappropriate.

Furthermore, the present inventors have confirmed that similar results can be obtained for the magneto-optical recording element shown in FIG. 3 in addition to the above embodiment.

〔The invention's effect〕

As described above, according to the magneto-optical recording element of the present invention, the dealcohol-type silicone resin is used as the adhesive resin, thereby eliminating stress corrosion, and the resin makes the magnetic layer and the substrate chemically resistant. As a result, a high-performance and long-term reliable magneto-optical recording element having excellent magneto-optical recording characteristics and maintaining its initial characteristics could be provided.

[Brief description of the drawings]

FIG. 1 is a sectional view showing the layer structure of each magneto-optical recording member before bonding, FIG. 2 is a sectional view showing the layer structure of the magneto-optical recording element of the present invention, and FIG. 3 is a magneto-optical recording element of the present invention. FIG. 4 is a sectional view showing a layer structure of a conventional magneto-optical recording element, and FIG. 5 is a diagram showing a temporal change of a bit error rate. 1a, 1b, 1c, 1d, 6 ... substrate 2a, 2b, 2c, 2d, 7 ... magnetic layer 4, 5, 9 ... adhesive resin layer A, B, C, D ... magneto-optical recording member

Claims (2)

(57) [Claims] 1. A magneto-optical recording element in which at least a magnetic layer, an adhesive resin layer, and a second substrate are sequentially formed on a first plastic substrate, wherein the adhesive resin layer is made of a dealcohol-type silicone resin. And elastic modulus is 1.5 × 10 ⁷ dy
A magneto-optical recording element characterized by being set to n / cm ² or less. 2. A first magneto-optical recording member having at least a magnetic layer formed on a plastic substrate, a second magneto-optical recording member having at least a magnetic layer formed on a plastic substrate, and a first magneto-optical recording member. In a magneto-optical recording element comprising an adhesive resin layer for bonding the magneto-optical recording member and the second magneto-optical recording member, the adhesive resin layer is made of a dealcohol-type silicone resin and has an elastic modulus of 1.5 × 10 ^7. dyn / cm
^A magneto-optical recording element characterized by being set to ² or less.