JPH1186343A - Optical information medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make the improvement in the bonding strength of an optical information recording medium formed by bonding two sheets of disks, the improvement in the durability thereof to oxidation and corrosion by the effect of moisture and atm. air, the prevention of its surface flaws, etc. SOLUTION: This optical information recording medium is formed by bonding two sheets of the disks 1, 5 to each other and providing at least one bonding surface side of these disks 1, 5 with an information recording layer 2 including an org. dyestuff film 12. The surfaces of the disks 1, 5 are coated with a coating film 15 continuous over both main surfaces of the disks 1, 5. Such coating film 15 may be made continuous only on either one of the inner periphery and outer periphery of the disks 1, 5 and is more preferably continuous on both of the inner periphery and outer periphery of the disks 1, 5. The film thickness of the coating film 15 made larger on the peripheral surface side of the disks 1, 5 than on the main surface side.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical information medium having an information recording layer containing an organic dye film and capable of recording optically readable information on the information recording layer. The present invention relates to a bonded optical information medium.

[0002]

2. Description of the Related Art With the recent development and commercialization of short-wavelength lasers, digital video discs (DVDs) capable of higher-density recording and reproduction have been put to practical use. In this type of optical information medium, an information recording area is set on at least one main surface, and a signal for reading information is recorded in the information recording area. The most common signal recording means in such an optical information medium capable of optically reproducing signals is to form pits in advance on a light-transmitting substrate molded by means such as injection molding. By providing a reflective layer made of a metal film thereon, optical signals can be reproduced.

[0003] In addition to an optical information medium in which a signal is recorded on a surface of a light-transmitting substrate by pits or the like previously formed by injection molding or the like, an optical information medium that can be additionally recorded after the optical information medium is manufactured. Development of an information medium, for example, an optical information medium such as a DVD-R is under study. As such a recordable optical information medium, a tracking guide is formed in an information recording area of at least one disk, and an organic dye film is formed thereon by applying an organic dye or the like by a method such as spin coating. A reflective layer made of a metal film is formed thereon. For example, in the DVD-type optical information medium, the organic dye film, the reflection layer, and the like are formed on at least one of the disks, and the two disks are bonded to each other on the layer side.

[0004]

In such an optical information medium, since two disks are bonded to each other, the disks are liable to peel off due to an external impact, and the like.
There was a problem that it lacked impact resistance. In particular, in a DVD-R capable of recording only once, an information recording layer containing the organic dye film as described above is formed on the surface of the disk, and the side on which the information recording layer is formed is bonded to another disk. There is a problem that the disk is easily peeled off at the organic dye film portion, and the strength of the adhesive surface between the disks against impact is weak.

When water or the like adheres to the optical information medium, 2
Water easily permeates between the discs, and the recording surface may be stained by the water. When not only water but also moisture, oxygen, and other corrosive substances present in the air penetrate between the disks, oxidation of the reflective layer formed of an organic dye film or a metal film formed of a dye or the like formed between the disks may occur. Deterioration such as corrosion easily occurs. Further, the disc to be bonded is mainly composed of a light-transmitting substrate made of a transparent resin such as polycarbonate and polymethyl methacrylate (PMMA). However, the surface of such a light-transmitting substrate is damaged. Then, not only is the appearance unfavorable, but also the incident reproduction light or the like is scattered, and the reproduction is hindered.

[0006]

SUMMARY OF THE INVENTION In view of the above-mentioned problems in the conventional optical information medium, the present invention combines two disks having an information recording layer on at least one side as described above. It is an object of the present invention to improve the bonding hardness of an optical information medium, improve the durability against oxidation or corrosion to moisture or air, and prevent the occurrence of surface scratches.

In order to achieve this object, according to the present invention, the surfaces of the two discs 1 and 5 bonded to each other are covered with a continuous coating film 15 over both main surfaces thereof, whereby the two discs in the organic dye layer are formed. This prevents the disk from peeling off. In addition, by making the coating film 15 water-repellent or having a hardness higher than the surfaces of the disks 1 and 5, the durability of the optical information medium as a whole against external forces, the environment, and the like is improved. .

That is, the optical information medium according to the present invention
The discs 1 and 5 are bonded together, and at least one of the discs 1 and 5 has an information recording layer 2 including an organic dye film 12 on the side of the discs. It is characterized in that it is covered with a continuous coat film 15 over both main surfaces 1 and 5.

In such an optical information medium, the disk 1,
Since the coating film 15 covering the surface of the disk 5 is continuous over both main surfaces of the disks 1 and 5, the disks 1 and 5 are fixed to each other by the coating film 15. Thus, when the optical information medium is impacted, the most fragile organic dye film 12
It becomes difficult for the disks 1 and 5 to peel off from each other at the portion. Therefore, it is preferable that such a coating film 15 is thicker on the inner and outer peripheral surfaces of the disks 1 and 5 in order to prevent peeling. Specifically, the thickness of the coating film 15 on the peripheral surface side of the disks 1 and 5 is 1
It is preferably from 15 to 15 μm. This is coat film 1
When the thickness of the coating film 15 is 1 μm or less, the effect of reinforcing the bonding strength of the disks 1 and 5 is poor. On the other hand, when the thickness of the coating film 15 is 15 μm or more, the thickness direction of the disks 1 and 5 during shrinkage after coating. Is liable to be excessively large, which tends to cause deformation of the disks 1 and 5, the change of the organic dye layer 12, and the like. Further, the above-mentioned coat film 15
Is continuous with one of the inner and outer peripheries of the disks 1 and 5, and covers either the inner or outer perimeter, so that water or moisture can flow between the disks 1 and 5 from the inner or outer perimeter. Hard to penetrate

Further, when the coating film 15 has a water-repellent surface, the surface of the optical information medium repels water, and even if it is touched by a wet hand, entry of moisture from the surface is prevented. You. As a result, it is possible to reliably prevent water from penetrating between the disks 1 and 5 and deteriorating the organic dye film, the reflective layer, and the like. Further, when the coating film 15 is harder than the hardness of the surfaces of the disks 1 and 5, it is possible to prevent the surfaces of the disks 1 and 5 from being damaged.

[0011]

Embodiments of the present invention will now be described specifically and in detail with reference to the drawings. As an example of an optical information medium according to the present invention, an example of a write-once optical information medium having a single-sided recording / reproducing structure by double-sided bonding is shown in FIGS. The disk 1 is a transparent disk-shaped substrate having a center hole 4 at the center. The disk 1 is best made of a transparent resin such as polycarbonate, polymethyl methacrylate (PMMA), epoxy, polyester, polyvinyl chloride, polyolefin, etc., but may be a glass substrate.

A clamping area, which will be described later, is set outside the center hole 4 on one side of the light-transmitting disc 1, and an information recording area r is set on the outer peripheral side. A tracking guide 3 composed of a spiral groove is formed in the information recording area r of the disk 1. The standard pitch of the tracking guide 3 is 0.74 to 0.8 μm.

Further, the information recording area r of the disc 1
The information recording layer 2 is formed on the main surface of the portion. For example, as shown in FIG. 2, an organic dye is first applied by means of a spin coating method or the like to form an organic dye film 12, and further, on this organic dye film 12, gold, aluminum, silver, copper, etc. The reflection layer 13 made of a metal film or an alloy film thereof is formed. A protective layer 14 such as a resin may be formed on the reflective layer 13, but may not be provided. 1 and 2, reference numeral 9 denotes a ring-shaped ridge 9 on the recording surface side, which is the main surface on the front side of the disk 1, and formed outside the information recording area r. This prevents the recording surface from touching the surface of another optical information medium when the optical information medium is superimposed.

Further, another disk 5 is prepared in addition to the disk 1. The disk 5 is of the same size and made of the same material as the disk 1, but does not have the tracking guide 3 and the information recording layer 2 provided on the main surface as in the disk 1. Of course, the other disk 5 can also be provided with an information recording area r having the same tracking guide 3 and information recording layer 2 as the disk 1.

Next, these two disks 1 and 5 are bonded together. For example, a reactive curable resin is applied as an adhesive to at least one main surface of the two disks 1 and 5 by means such as spin coating or screen printing,
Further, these surfaces are overlapped so as to face each other, and the reactive curable resin is cured. Thereby, the main surfaces of the two disks 1 and 5 are bonded to each other by the adhesive layer 11 formed by curing the reactive hardening resin. In this case, the surface of the disk 1 on which the information recording layer 2 is formed is bonded.

For example, with at least one of the disks 1 and 5 to be bonded facing upward, an ultraviolet-curable resin liquid not cured as an adhesive is applied onto the same circumference on the inner peripheral side of the upper surface. Drip along. Thereafter, the predetermined surfaces of the two disks 1 and 5 to be bonded are overlapped with each other, and the two disks 1 and 5 are rotated at a high speed to spread the ultraviolet curable resin uniformly on the outer peripheral side between the disks 1 and 5. . Next, ultraviolet rays are irradiated to the ultraviolet curable resin from one side of the transparent disks 1 and 5 and cured to form an adhesive layer 11.
1 tightly fixes both disks 1 and 5.

As another example, a cationic UV-curable resin is applied over the entire surface of at least one of the disks 1 and 5 to be bonded, and UV-irradiation is applied thereto to start slow-acting curing. After that, two discs 1,
The predetermined surfaces 5 to be bonded are overlapped with each other. Next, the resin is cured while pressing both disks 1 and 5 in the thickness direction to form an adhesive layer 11, and the disks 1 and 5 are tightly fixed by the adhesive layer 11. In addition to this,
A thermoplastic resin-based adhesive can also be used as the adhesive. In consideration of the impact resistance of the optical information medium, the hardness of the adhesive layer after curing is preferably higher than the hardness of the substrate.

In the above example, the information recording area r of the translucent substrate is used.
A disc 1 on which a tracking guide 3 and an information recording layer 2 are formed, and another disc 5 on which an information recording layer is not formed.
This is an example in which are bonded together. In these cases, recording / reproduction is possible on only one side. The other disk 5 may have no translucency or may be colored, or may have a surface on which characters, patterns, and writable areas are provided for decoration or display.

On the other hand, two disks 1 provided with a tracking guide 3 and an information recording layer 2 in an information recording area r of a light-transmitting substrate are prepared, and these two information recording layers 2 are opposed to each other and bonded. A combined optical information medium having a so-called double-sided recording / reproducing structure can also be used. As the other disk 5 used in this case, one of the disks 1 and 5 shown in FIG. 1 in which the tracking guide 3 and the information recording layer 2 are formed in the information recording area r like the disk 1 is used.

In the present invention, in such an optical information medium, the surfaces of the disks 1 and 5 are covered with the coating film 15. The coating film 15 is preferably transparent, has water repellency, and is harder than the surfaces of the disks 1 and 5. A resin material as a coating material is dissolved in a solvent, applied to the surfaces of the disks 1 and 5 by spin coating, and cured to form a coating film 15. In addition to the spin coating method, a resin material may be applied to the surfaces of the disks 1 and 5 by a spray method and cured to form the coat film 15.

As the coating material, an ultraviolet curable resin having a longer life than the disks 1 and 5 is suitable. For example,
As a resin material for the coating film 15, San Nopco S
Any of the N-5X part numbers 2675 to 2678 is suitable. This is applied to the surfaces of the disks 1 and 5 by spin coating, and is irradiated with ultraviolet rays to be cured, thereby forming a coat film 15.

The coating film 15 is applied such that the peripheral surfaces of the disks 1 and 5 are thicker than the main surface. For example,
By applying the coating material back and forth on the main surfaces of the disks 1 and 5, the coating material is applied twice as many times as the main surfaces of the disks 1 and 5 on the peripheral surfaces of the disks 1 and 5. Accordingly, the thickness of the coating material increases accordingly. The thickness of the coat film 15 on the peripheral surfaces of the disks 1 and 5 is 1 to 15
μm, and is usually applied to a thickness of 5 to 8 μm.

In the example of the optical information medium shown in FIG. 2, the coating film 15 is provided over the entire main surface of the disk 1 and the entire main surface of the disk 5, and the coating film 15 covering the main surfaces of the disks 1 and 5 is provided. Are continuous via a coating material 15 covering the outer peripheral surfaces of the disks 1 and 5. The coat film 15 is not formed on the inner peripheral side of the disks 1 and 5. On the other hand, in the example of the optical information medium shown in FIG. 3, the coat film 15 is provided over the entire main surface of the disk 1 and the entire main surface of the disk 5, and the coat film 15 covering the main surfaces of the disks 1 and 5 is provided. It is continuous via a coating material 15 that covers the inner and outer peripheral surfaces of the disks 1 and 5. That is, the coat film 15 is also formed on the inner peripheral side of the disks 1 and 5.

Further, in the example of the optical information medium shown in FIG.
A coating film 15 is provided over the entire main surface of the disk 1 and the entire main surface of the disk 5, and the coating film 15 covering the main surfaces of the disks 1 and 5 is a coating material 15 covering the inner peripheral surfaces of the disks 1 and 5. Is continuous through. The coat film 15 is not formed on the outer peripheral side of the disks 1 and 5. In this way, by making the coating material 15 provided on the main surfaces of the disks 1 and 5 continuous through the inner circumference or the outer circumference of the disks 1 and 5, the coating material 15 provided on the main surfaces of the disks 1 and 5 is formed. Are integrated, and the bonding of the disks 1 and 5 is reinforced. The airtightness and strength of the bonded portions of the disks 1 and 5 are the highest in the example of FIG. 3, and higher impact resistance can be obtained, and the deterioration of the information recording layer and the like due to moisture, air, and the like. Can be reliably prevented.

As shown in the example of the optical information medium shown in FIG. 3, one disk 1 made of polycarbonate is provided with an organic dye film 12 made of a color material and a reflection layer 13 made of a metal film.
This surface is bonded to another disk 5 made of polycarbonate using an adhesive made of a reaction curable resin.
In VD-R, Sannopco's SN-5X product number 2
675 was applied by a spin coating method to produce an optical information medium in which the entire surfaces of the disks 1 and 5 were covered with a coating film 15 having a thickness of 6 μm on the main surfaces of the disks 1 and 5 and a thickness of 9 μm on the peripheral surface. The optical information medium was naturally dropped on a concrete floor surface while guiding the optical information medium from a height of 1 m in the radial direction, and the outer peripheral edge portion was caused to collide perpendicularly with the floor surface. However, destruction such as partial peeling of disks 1 and 5 was not observed in 100 optical information media.
On the other hand, when a similar destruction test by natural fall was performed on the optical information medium having no coat film 15 as described above, 20 out of 100 optical information media were discs 1 and 5.
Destruction such as partial peeling was observed.

[0026]

As described above, according to the present invention, it is possible to reinforce the bonding of the disks 1 and 5 so that the disks 1 and 5 are hardly damaged by peeling or the like, and to prevent the disks 1 and 5 from being damaged by water or moisture. It is possible to prevent the organic dye film 12 and the reflective layer 13 from being deteriorated between 1 and 5. This allows
It is possible to improve the durability of the optical information medium against external force such as impact and the weather resistance against environment such as moisture.

[Brief description of the drawings]

FIG. 1 is an exploded half cross-sectional perspective view showing an example of an optical information medium according to the present invention in a state before two disks are bonded together.

FIG. 2 is a partial longitudinal sectional view showing an example of the optical information medium.

FIG. 3 is a partial longitudinal sectional view showing another example of the optical information medium according to the present invention.

FIG. 4 is a partial longitudinal sectional view showing another example of the optical information medium according to the present invention.

[Explanation of symbols]

 1 disk 5 disk 2 information recording layer 12 organic dye film 15 coat film

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yuju Tomizawa 6-16-20 Ueno, Taito-ku, Tokyo Inside Taiyo Denki Co., Ltd. (72) Emiko Hamada 6-16-20 Ueno, Taito-ku, Tokyo Taiyo Denki Co., Ltd.

Claims (5)

[Claims] 1. An information recording apparatus comprising two disks (1) and (5) bonded together and an organic dye film (12) on at least one of the disks (1) and (5) bonded surfaces. In the optical information medium having the layer (2), the surfaces of the discs (1) and (5) are covered with a coat film (15) continuous over both main surfaces of the discs (1) and (5). Optical information medium. 2. The optical information medium according to claim 1, wherein the film thickness of the coat film (15) is larger on the peripheral surface side of the disks (1) and (5) than on the main surface side. 3. The optical information medium according to claim 1, wherein the thickness of the coat film (15) is 1 to 15 μm on the peripheral surface side of the disks (1) and (5). 4. The optical information medium according to claim 1, wherein the surface of the coat film (15) has water repellency. 5. The coating film (15) includes a disk (1),
2. The method according to claim 1, wherein the hardness is higher than the surface of (5).
An optical information medium according to any one of claims 1 to 4.