JPH0773507A - Optical information recording medium - Google Patents

Abstract

PURPOSE:To prevent the deterioration of recording layers and reflection layers and the deterioration of mechanical characteristics by adhering two sheets of recording media for which materials to be oxidized are used by using a double coated tacky adhesive member contg. a silicone tacky adhesive without contg. halogen atoms in skeleton. CONSTITUTION:Recording films consisting of a Te alloy or reflection films 2a, 2b consisting of Au, At, Al alloy, etc., are laminated by vacuum vapor deposition, etc., on the respective one surfaces of disk-shaped substrates 1a, 1b. These substrates 1a, 1b are stuck to each other by the double coated tacky adhesive member 3 in such a manner that the recording films (or reflection films) are positioned on the inner side. The double coated tacky adhesive member 3 is formed by laminating the tacky adhesive layers 5a, 5b of a silicone system which does not contain the halogen atoms, for example, fluorine, in its skeleton on both surfaces of a base material 4 having a thickness of about several tens microns to several hundreds microns. There is no generation of gases from the tacky adhesives in such a case and the good characteristics are maintained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical information recording medium capable of reproducing or recording / reproducing information with a laser or the like.

[0002]

2. Description of the Related Art An optical information recording medium is generally used in a state in which two discs are stuck together with a recording film inside in order to increase the recording capacity. The laminating structure includes an air sandwich structure in which only the inner and outer peripheral portions of the disc are laminated with a spacer so that the middle peripheral portions where the recording layers are laminated are not in contact with each other, and the entire surface of the two discs. Can be roughly classified into two types, that is, a full-surface adhesion (solid pasting) structure, which is used properly depending on the recording method.

Of these two structures, the latter whole surface adhesive structure is generally used for various optical disks such as a read-only optical video disk and a recordable / reproducible magneto-optical disk. Conventionally, a solvent type adhesive was used as an adhesive for obtaining this structure (Japanese Patent Laid-Open No. 4-168635). However, when this type of adhesive is used, a disk substrate, a reflective surface, Alternatively, the recording surface may be touched or curing distortion may occur. Therefore, as a simple method for improving this, a method using a hot melt adhesive has been proposed (JP-A-63-67258),
It has become widely used.

However, according to this method, heat is applied to the disk substrate mainly made of resin, and there is a concern that the substrate may be deformed. Therefore, a bonding method using a double-sided adhesive sheet (Japanese Patent Laid-Open No. 1-276447) has been proposed as a bonding method that does not adversely affect the substrate and the recording film and does not require heating.

As the pressure-sensitive adhesive used for the double-sided pressure-sensitive adhesive sheet, natural rubber pressure-sensitive adhesives, acrylic pressure-sensitive adhesives, SIS type hot-melt pressure-sensitive adhesives, etc. are used in general applications, but at present, acrylic pressure-sensitive adhesives are used. It is the mainstream. Also in bonding optical disks, acrylic adhesives are generally used in terms of functionality, weather resistance, low contamination, and ease of handling.

On the other hand, in order to provide an optical disk to a reproducing apparatus or a recording / reproducing apparatus, very high precision mechanical characteristics are required, but in a structure in which thin resin substrates are bonded together, a disk having a particularly large diameter is used. It is difficult to maintain good mechanical properties such as warpage and distortion. Therefore, a structure has been devised in which a disk and a high-rigidity reinforcing plate are adhered to maintain mechanical properties (Japanese Patent Laid-Open No. 61-21424).
5). Further, in an optical disc using a resin substrate, there may be a structure in which the two resin substrates are entirely adhered to both surfaces of the core material by the above-mentioned hot melt adhesive or other adhesive.

[0007]

As described above, the prior art is as follows.
The two disks were adhered over the entire surface using an acrylic adhesive. However, the acrylic pressure-sensitive adhesive generates gas when exposed to a high temperature environment. At this time, a Te alloy is used for the recording layer, or Au, A is used for the reflective film.
In the case of using Al, Al alloys, etc., these metals are likely to be oxidized, so that they may be contaminated by gas or cause deterioration of the mechanical properties of the disk. As a result, there is a problem in that the disc is locally deformed, resulting in reduced sensitivity and loss of signal. SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an optical information recording medium having an entire adhesion structure, which does not cause deterioration of a film or deterioration of mechanical properties.

[0008]

According to the present invention, two recording media each having at least one layer of a film containing an oxidizable material laminated on a substrate are used as a silicone-based adhesive containing no halogen atom in the skeleton. Provided is an optical information recording medium, characterized in that the entire surface is adhered using a double-sided adhesive member containing an agent.

Further, according to the present invention, two recording media comprising at least one layer of a film containing an oxidizable material laminated on a substrate are provided on both sides of a rigid reinforcing base material having a thickness of 0.5 mm or more. To
There is provided an optical information recording medium characterized by being adhered on the entire surface by using a double-sided adhesive member having a silicone-based adhesive layer containing no fluorine atom in its skeleton.

[0010]

The optical information recording medium of the present invention has a structure in which two discs are laminated with the recording film or the reflective layer inside, and the silicone-based optical system does not contain halogen atoms in the skeleton. A double-sided adhesive member containing an adhesive is used.
The silicone-based pressure-sensitive adhesive containing no halogen atom in the skeleton does not generate a gas even when heated, so that the problem that the recording film or the reflective layer is deteriorated by the gas does not occur. Moreover, since the adhesion is not impaired by the generation of gas, it is possible to obtain an optical information recording medium excellent in durability without deterioration of mechanical properties.

[0011]

EXAMPLES Hereinafter, the present invention will be described more specifically by showing various examples of the present invention. FIG. 1 is a sectional view showing an optical information recording medium according to an embodiment of the present invention. In FIG. 1, a recording film made of Te alloy or reflective films 2a, 2b made of Au, Al, Al alloy or the like are laminated on one surface of each of the disk-shaped substrates 1a and 1b by vacuum deposition or the like. The substrates 1a and 1b are attached by the double-sided adhesive member 3 with the recording film (or the reflection film) inside.

The recording films 2a and 2b are made of GeSbTe and Bi.
Te alloy film such as Te, SbTe, GeTe, or A
u, Al or Al alloy films, which are used as recording films (partly reflective films) of phase change type, write-once type, partial ROM, etc., or as reflective films of full ROM, CD-ROM, etc. is there. Further, these films have a property of being easily oxidized.

As shown in FIG. 2, the double-sided adhesive member 3 has a base material 4 having a thickness of about several tens of microns to several hundreds of microns.
Silicone adhesive layers 5a and 5b containing no halogen atom, for example, fluorine, in the skeleton are laminated on both surfaces of. When the injection-molded substrate is used as the disk substrate, the thickness of the pressure-sensitive adhesive layer is set to absorb the unevenness of the thickness,
It is desirable that the thickness is at least 15 μm or more.
The material of the base material 4 needs to be a material that is stable even in an environment such as high temperature, as represented by PET.

The silicone-based material has a molecular structure shown in the following chemical formula 1, but the generated gas is actually examined for a silicone-based pressure-sensitive adhesive in which R (alkyl group) does not contain halogen such as fluorine. Apparently, 160
Generation of decomposition gas was not observed up to about 200 ° C. On the other hand, when the same test was performed on the acrylic pressure-sensitive adhesive that was conventionally used, decomposition gas was generated when the temperature was raised to about 60 to 80 ° C. From these results, the silicone-based pressure-sensitive adhesive containing no fluorine is stable under the environment of use as well as when the pressure-sensitive adhesive layer portion is locally heated during repeated recording or the like without generating gas.

[0015]

[Chemical 1]

Next, a method for laminating two discs to obtain the optical information recording medium of the present invention will be specifically described. The double-sided adhesive member 3 used for bonding is
As shown in FIG. 3, the pressure sensitive adhesive layer surfaces on both sides are separated by the separator 6
It is covered with a and 6b, the adhesive surface is protected until it is used, and it is processed into a ring-shaped sheet with the same inner and outer diameters as the bonded substrate for easy bonding. It is said to be an adhesive ring.

The two disk substrates can be bonded together by the double-sided adhesive member 3 using a means such as a laminator or a press, but in the whole-surface bonding structure such as the present invention, especially on the bonding surfaces. The best method is the laminating method using a vacuum press that prevents bubbles and laminating unevenness from remaining.

An example of the vacuum press device is shown in FIG. The first disk substrate 1a on which the recording film 2a has been formed and the one in which one of the separators 6a of the adhesive ring shown in FIG. 3 has been peeled off are respectively bonded as shown in FIG.
Fixed to and stack them with some gap maintained. After that, press pressure sufficient to eliminate the gap is applied by using hydraulic pressure and air pressure.

The pressing pressure at this time may be a pressure sufficient for releasing the gap, and considering the influence on the disk substrate, it is 10 kg / cm ² or less, preferably 6 kg / cm ^2.
The following is good.

At this time, the inside of the apparatus is kept in a vacuum state by evacuating from the exhaust port 9 in the direction of the arrow. According to our research, the effect of such a vacuum press is several tens.
It appears from around Torr, and no visible unevenness in lamination is observed, but considering environment resistance and long-term reliability,
It is desirable that the pressure is 1 Torr or less.

In this way, the bonding of the double-sided adhesive member and the first disk substrate 1a is completed within a pressing time of several seconds. Then, the other separator 6b of the adhesive ring shown in FIG. 3 is peeled off, and similarly, as shown in FIG. 4 (b), the second disk substrate 1b is attached.

The optical disk obtained by the above-mentioned bonding method has neither air remaining on the bonding surface nor generated gas, so that the recording film is not adversely affected by these and the mechanical characteristics are not deteriorated, and the durability is improved. It is an excellent one.

The results of a comparative test of the characteristics of the optical disk according to this embodiment and the conventional optical disk will be described below. Figure 1
Let A be an optical disk of this embodiment having the structure shown in FIG. 1 and having the recording films 2a and 2b made of GeSbTe. On the other hand, an optical disk of the conventional structure in which the adhesive of the double-sided adhesive member 3 is replaced with an acrylic double-sided adhesive with the same recording film is designated as B. In addition, both the lamination was performed by a vacuum press.

FIG. 5 shows the optical discs A and B of 60.
It is a characteristic view which shows C / N change at the time of carrying out an environmental test for 2000 hours in an atmosphere of 85 ° C and 85% RH. From FIG. 5, the optical disc A (straight line A) has a C / N by an environmental test.
Although no deterioration is observed, it can be seen that the optical disk B (curve B) is greatly deteriorated. At this time, discoloration due to film oxidation was observed on the optical disc B.

FIG. 6 is a characteristic diagram showing mechanical characteristics due to the above environmental test, in particular, surface wobbling acceleration which is considered to have a great influence on the drive servo. From FIG. 6, it can be seen that there is almost no change in the optical disc A (straight line A), but the optical disc B (curve B) is greatly increased.

As described above, the optical disc according to the present embodiment exhibits extremely excellent durability as compared with the conventional optical disc. In addition, in the above-mentioned embodiment, the structure in which the discs in which only one recording layer or a reflective layer such as a Te alloy film is laminated is laminated is shown, but the recording layer or the reflective layer may have two or more layers. The recording film or the reflective layer may not be the uppermost layer. For example, as shown in FIG. 7, even if the recording film or the reflective layers 2a and 2b are covered with the protective films 8a and 8b to prevent oxidation, the effect of the present invention is sufficiently exhibited.

As shown in FIG. 8, the disk substrate 1
Instead of directly bonding a and 1b, it is also possible to adopt a structure in which the two double-sided adhesive members 3a and 3b are bonded to each other with the reinforcing plate 9 interposed therebetween.

In the case of a disc having a large diameter such as a disc diameter of 300 mm, especially when an injection molded plate is used, the disc is liable to sag. Therefore, the effect of the present invention is sufficiently obtained unless the disc is shaped as shown in FIG. It may not be possible to exert it. However, in the case of this structure, since there are two bonding points, the bonding step becomes complicated, the cost is increased, and the process yield may be reduced.

In order to address these problems, the second invention is to consider a disk structure in which a reinforcing plate is sandwiched without increasing the number of laminations. Examples of the second invention will be shown below.

The optical disc according to the second aspect of the present invention, as shown in FIG. 9 as one example, is a substrate 1 having a rigidity of 0.5 mm or more.
Silicon adhesive layer 15 containing no fluorine above and below 4
By the double-sided adhesive member 13 having a structure sandwiched between a and 15b, T
e alloy or Au, Al, Al alloy film layers 12a, 12
This is a structure in which disc substrates 11a and 11b in which b is laminated are laminated. The double-sided adhesive member 13 is, like the double-sided adhesive member shown in FIG. 3, actually an adhesive layer whose adhesive layer is protected by a separator is supplied to the laminating step, and the separator is peeled off before use. To be done.

The base material 14 is preferably rigid enough to maintain the mechanical characteristics of the optical disk, and is preferably made of a material having a thermal expansion coefficient close to that of the disk substrate. According to the detailed study by the present inventors, a polycarbonate plate or an acrylic plate having a thickness of at least 0.5 mm or more is suitable. However, the difference in thermal expansion is due to the elastic adhesive layer 13a,
Since it can be absorbed by 13b, it is possible to increase rigidity by using a metal such as reinforced plastic or aluminum as the base material.

The pressure-sensitive adhesive layers 13a and 13b are reinforcing base materials 14.
Are uniformly laminated on both surfaces by coating or the like, and the surface of the pressure-sensitive adhesive layer is covered with separators 16a, 16b coated with a silicon-based or Teflon-based treatment agent.
Then, a disk-shaped double-sided adhesive member as shown in FIG. 10 is obtained by processing this into a disk shape having the same inner and outer diameters as the disk substrate.

Usually, a so-called double-sided adhesive is manufactured by laminating a pressure-sensitive adhesive layer on a thin base material having a rigidity of about several tens to several hundreds of microns, and a double-sided adhesive as shown in FIG. In order to manufacture the member, not much process change is required.

Below, using the double-sided adhesive member of FIG. 10,
The laminating method for producing the optical disc according to the second invention will be specifically described. The optical disk substrate 11a on which the recording film 12a is formed and the one in which the separator 16a on one surface of the double-sided adhesive member 13 is removed are shown in FIG.
As shown in (a), it is fixed to a laminating device and these are superposed with a certain gap maintained. After that, press pressure sufficient to eliminate the gap is applied by using hydraulic pressure and air pressure. The pressure at this time may be a pressure sufficient to release the gap, and considering the influence on the disk substrate, it is 10 kg / cm ² or less, preferably 6 kg / cm ² or less.
kg / cm ² or less is recommended.

At this time, when the pressing was performed under atmospheric pressure, uniform bonding could not be performed, and air remained on the bonding surface, resulting in uneven bonding. In order to eliminate this uneven bonding, pressing is performed while discharging air between the devices with a vacuum pump or the like. That is, it is necessary to perform vacuum pressing.

According to the research conducted by the present inventors, the effect of the vacuum press appears from about several tens Torr, and the unevenness of sticking is not visually observed. However, considering the environment resistance and long-term reliability, it is 1 Torr or less. Is desirable.

In this way, the bonding of the double-sided adhesive member 13 and the first disk substrate 11a is completed in a pressing time of several seconds. After that, the separator 16b on the other surface of the double-sided adhesive member 13 is peeled off, and the second disk substrate 11b is attached in the same manner.

FIG. 12 shows another example of the laminating method according to the second invention. The method shown in FIG. 11 requires two vacuum pressing steps in which pressing is performed while vacuuming in the direction of the arrow from the exhaust port 9 until the bonding is completed.
The method shown in FIG. 12 requires only one vacuum pressing step. That is, the double-sided pressure-sensitive adhesive member used in the second invention can hold the inner peripheral surface or the outer peripheral side surface with a rigid material or the like, and can be fixed to the pressing device 17 as shown in FIG. 12, for example. it can.

Two discs having a recording film are held on both sides of this double-sided adhesive member with a certain gap kept therebetween, and the inside of the apparatus is directed from the exhaust port 19 in the direction of the arrow in the same manner as described above. After evacuating, the pressing pressure is applied at the same time in such a direction as to eliminate these gaps, so that the bonding can be completed by only one vacuum pressing. In the laminating process shown in FIG. 11, evacuation is a process that takes a relatively long time, but the time required for the laminating process can be greatly shortened by performing this only once.

Next, the results of environmental tests of the optical disk according to the second invention obtained by the above-mentioned bonding method and the conventional optical disk will be shown in comparison. The optical disk according to the second invention having the structure shown in FIG. 9 which is laminated by using the double-sided adhesive member shown in FIG. 10 is A ′, and the structure of FIG. 8 which is laminated by using the double-sided adhesive member and the reinforcing plate shown in FIG. Let C be the optical disk.

In the case of the optical disc A ', the bonding of these structures is performed in two steps as described above, but in the case of the optical disc C, it is performed between the disc substrate 1a and the reinforcing plate 11 in two steps.
In this case, a vacuum press of 4 steps in total, that is, 2 steps between the reinforcing plate 11 and the disk 1b, is required.

FIG. 13 shows these disks at 60 ° C.-8.
A change in mechanical characteristics (typically, a surface deviation value) of 5% × 2000H is compared with the above-mentioned disk B (a conventional disk in which a structure without a reinforcing plate and full-surface adhesion with an acrylic double-sided adhesive are performed). According to this, in B, the surface runout greatly increases by the environmental test, while in A ′ and C, good characteristics are maintained without any change.

FIG. 14 compares the yields of the disks A'and C up to the step before the laminating step and those after the laminating step. The yield of the disk C is slightly lower than that of the disk C, while that of the disk A ′ is almost unchanged and its effect is clear. Further, since the number of times of vacuum pressing is small, the manufacturing cost itself of the disk A'is also smaller.

As described above, the optical disk according to the second aspect of the present invention has better mechanical characteristics and yield than the conventional optical disk. Note that, in the above-mentioned examples, only the structure in which the recording surfaces are stuck facing each other is shown, but the disc substrate used in the present invention may be any disc as long as it has a recording layer or a reflective layer, As shown in FIG. 15, the recording layer or the reflective layer is covered with the protective layers 20a and 20b, that is, the surface in contact with the adhesive layer is the protective layers 20a and 20b.
May be

[0045]

As described above, according to the present invention,
Since a double-sided pressure-sensitive adhesive member containing a silicone-based pressure-sensitive adhesive containing no halogen atom in its skeleton is used to bond two recording media using an oxidizable material to the recording layer or the reflective layer, the gas from the pressure-sensitive adhesive is There is no occurrence, and as a result, deterioration of the recording layer or the reflective layer and deterioration of mechanical properties do not occur.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view of an optical disc according to an embodiment of the first invention.

FIG. 2 is a schematic cross-sectional view of a double-sided adhesive used for laminating the optical disks shown in FIG.

3 is a schematic cross-sectional view of a double-sided adhesive used for laminating the optical disks shown in FIG.

FIG. 4 is a diagram showing an example of a method for laminating the optical discs shown in FIG.

FIG. 5 is a characteristic diagram showing effects of the optical disc shown in FIG. 1 in comparison with a conventional optical disc.

FIG. 6 is a characteristic diagram showing the effect of the optical disc shown in FIG. 1 in comparison with a conventional optical disc.

FIG. 7 is a schematic cross-sectional view of an optical disc according to another embodiment of the first invention.

FIG. 8 is a schematic sectional view of an optical disc according to another embodiment of the first invention.

FIG. 9 is a schematic cross-sectional view of an optical disc according to an embodiment of the second invention.

FIG. 10 is a schematic cross-sectional view of a double-sided adhesive used for laminating the optical disks shown in FIG.

FIG. 11 is a diagram showing an example of a method for laminating the optical discs shown in FIG.

FIG. 12 is a diagram showing another example of a method for laminating the optical discs shown in FIG.

FIG. 13 is a characteristic diagram showing the effects of the optical disc shown in FIG. 9 in comparison with a conventional optical disc.

14 is a characteristic diagram showing the effect of the optical disc shown in FIG.

FIG. 15 is a schematic sectional view of an optical disc according to another embodiment of the second invention.

[Explanation of symbols]

 1a, 1b, 11a, 11b ... Optical disc 2a, 2b, 12a, 12b ... Recording layer or reflective layer 3, 3a, 3b, 13 ... Double-sided adhesive member 4 ... Base material 5a, 5b, 15a, 15b ... Adhesive layer 6a, 6b ... 16a, 16b Separator 7, 17 ... Vacuum laminating apparatus 8a, 8b, 20a, 20b ... Protective layer 9 ... Reinforcing material 14 ... Rigid reinforcing base material

Claims (2)

[Claims] 1. A two-sided recording medium comprising at least one layer of a film containing an oxidizable material laminated on a substrate, using a double-sided adhesive member containing a silicone-based adhesive containing no halogen atom in its skeleton. An optical information recording medium characterized in that the entire surface is adhered. 2. Two recording media comprising at least one layer of a film containing an oxidizable material laminated on a substrate, on both sides of a rigid reinforcing base material having a thickness of 0.5 mm or more, in a skeleton. An optical information recording medium, wherein the entire surface is adhered using a double-sided pressure-sensitive adhesive member having a silicone-based pressure-sensitive adhesive layer containing no fluorine atom.