JPS60219649A - Information recording medium - Google Patents

Abstract

PURPOSE:To minimize the deterioration of a recording film without causing exfoliation of a bonded part even under the environment of high temperature and high humidity by bonding two disc bases fully with an optical guide groove and an optical recording film by means of an adhesive of distortion absorbing performance with less elastic coefficient. CONSTITUTION:The optical guide pit 2 is provided to the disc base 1a and the optical recording film 3 is vapor-deposited. The disc base 1 made as above is bonded fully with the disc base 1b made of polycarbonate resin similarly while taking the optical recording film to the inside by means of the photocuring elastic adhesives 6. Thus, the disc base tends to leave the internal stress due to thermal distortion and the distortion by the stress is generated conversely under the condition of high temperature and high humidity. However, the adhesive 6 itself has an elasticity through the constitution above and it is smaller than the elastic coefficient of the disc base, then even if a minute distortion is produced on the disc base 1a, the elastic adhesives 6 follows up the distortion and no exfoliation takes place.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a disk-shaped information recording carrier used in optical recording or reproducing systems.

Conventional configuration and its problems In the optical recording and reproducing system, the optical recording layer of a rotationally driven disk-shaped information recording carrier (hereinafter referred to as a disk) is irradiated with a laser beam corresponding to an information signal. It records and reproduces information by providing optical shading or unevenness on the optical recording layer, and is capable of recording minute signals of several micrometers, and in principle enables high-density recording on the order of the wavelength of light. It is a method. Also, during recording and playback, the laser beam's big amplifier and the disk do not come into contact, so there is no wear, and still images and
You can get multiple functions such as high-speed search. Therefore, it is being put to practical use in industrial applications as an additional storage type disk memory for still image files, document files, computer data files, etc.

In addition, in recent years, in the information society, streamlining office automation, laboratory automation, etc. has become important, and in response to these demands, additional storage type disks that allow users to freely record and play back are being developed. Optimal. At the same time, there is a need for high-performance component materials, including a highly sensitive recording medium, and a disk structure that does not cause deterioration of the recording medium due to changes in the external environment.

Next, an example of the deterioration of the recording film of a conventionally used disk will be explained with reference to a drawing. In FIG. 1, a disc base material 1a made of polycarbonate resin is provided with grooves 2 for guiding light, and a recording film 3 is deposited thereon. The disk substrate 1 made of these includes a disk base material 1b made of polycarbonate resin and a photocurable adhesive 4.
The entire surface is joined by

Especially when such disk base materials 1a and 1b are manufactured by injection molding, many of them have internal stress,
Thermal strain is likely to occur in high temperature and high humidity environments. Therefore, if the adhesive 4 that joins the two disc base materials is of high rigidity, for example, as shown in FIGS. Minute peeling 5a, 5b may occur between the adhesive 4 and the adhesive 4. This is because the highly rigid adhesive cannot follow the thermal distortion of the disk base material and attempts to stabilize by generating minute peels.0 These minute peels 6a
, 5b occur at different locations depending on the difference in adhesive force between the disk base material and the recording film or between the recording film and the adhesive.

Once such minute peeling occurs, the peeling is likely to be accelerated and has a good possibility of spreading to the surrounding area. This is because the stress that causes initial peeling and the stress that forces apart existing peeling have different mechanisms, and the latter can be generated with a smaller force.

Such micro-separations are initially in a vacuum state, so when ventilation occurs with the outermost or innermost part of the disk that is in contact with the outside air, outside air can be instantly drawn into the separated area. become.

Therefore, if the outside environment is high temperature and humidity, materials that are easily affected by humidity may oxidize and accelerate deterioration.

Even if the recording film is shielded from the outside air by a polycarbonate resin with relatively low water permeability, if peeling occurs, the effect disappears and this poses a serious problem in terms of disk reliability. Even if the peeling does not expand and remains as a microscopic peel, it will still be affected by laser light irradiation during recording and playback, and the reliability of the disc will be lost due to the deterioration of its characteristics. become.

Purpose of the Invention The present invention eliminates the above-mentioned drawbacks and provides a highly reliable information recording carrier that does not cause peeling of joints even under high temperature and high humidity environments and minimizes deterioration of the recording film. It is something.

Structure of the Invention The present invention provides a method of joining two disk substrates, each of which has a groove for guiding light and an optical recording film on at least one side thereof, by joining them together on their entire surfaces using a strain-absorbing adhesive with a small elastic modulus. This prevents surface peeling and makes it possible to manufacture discs with high reliability in terms of optical recording films.

Description of examples A first embodiment of the present invention will be described with reference to the drawings.

In FIG. 3, the same parts as in FIGS. 1 and 2 are designated by the same numbers and will be explained. In FIG. 3, a disc base material 1a made of polycarbonate resin is provided with grooves 2 for guiding light, and an optical recording film 3 is deposited on the surface thereof. A disk substrate 1 made of these materials is bonded to a disk substrate 1b made of polycarbonate resin on its entire surface using a photocurable elastic adhesive 6, with the optical recording film inside.

Here, it is necessary to manufacture the optical guide groove 2 integrally with the disk base material by injection molding in order to reduce costs. However, internal stress due to thermal strain tends to remain in such a disk base material, and under high temperature and high humidity conditions, this stress causes strain.

However, according to the configuration of this embodiment, since the adhesive 6 itself has elasticity, even if a minute strain occurs in the disk base material 1a, the elastic adhesive 6 will not be strained as shown in FIG. It moves according to the movement and does not cause peeling.

Additionally, it is generally difficult to select an adhesive that has exactly the same coefficient of thermal expansion as the adhesive bonded to the disk base material 1a.
When the temperature rises, stress is generated due to the different amounts of elongation, and adhesives with high rigidity are likely to peel off.

The same thing can be said in the case of swelling due to moisture absorption of the disk base material, and in a high temperature and high humidity environment, the effects of both thermal expansion and swelling are most significant.

Even in such a case, as shown in FIG.
It is possible to absorb the strain by using
Occurrence of peeling can be prevented.

For example, as shown in FIG. 6, if the elongation 7 due to thermal expansion and swelling of the disk base material is larger than the elongation 8 due to thermal expansion and swelling of the elastic adhesive 6, the stress due to the difference in the amount of elongation is elastic. This is stored in the adhesive 6 as internal stress 9. Since the elastic modulus of the elastic adhesive is small, even if the deformation is large, the internal stress 9 is small and does not cause peeling at any of the interfaces.

Of course, in this case, if the adhesive strength of the elastic adhesive to the disk base material, optical recording film, etc. is too small, peeling may occur, but the elastic modulus of the elastic adhesive is EKg/I+Il.
++ If the stress is small, the internal stress will be smaller than σ = Eε (σ: internal stress, ε: strain), and it is relatively easy to use an elastic adhesive with adhesive strength that can withstand this stress.0 Thermal expansion and swelling The same phenomenon occurs not only when the disk base material is manufactured by injection molding, but also when the disk base material is manufactured by a manufacturing method such as cast molding.

The physical constants related to the elasticity of the elastic adhesive of this example include a longitudinal elastic modulus, a transverse elastic modulus 2 a bending elastic modulus, etc., and it can be said that the smaller these values are, the better the elasticity is. According to experiments, these elastic modulus AKg/
rm2 is 1oKy/throat2≦A <200 Kf
/ rran2-r: If there was, a product with no particular problem was obtained.

Furthermore, it is necessary that the elastic modulus of the elastic adhesive is at least smaller than that of the disk base material, and it has been recognized that the greater the difference between the two, the greater the effect.

Next, a second embodiment of the present invention will be described with reference to the drawings. FIG. 6 shows two disc base materials 1a and 1b made of polycarbonate resin with grooves 2a and 2b for guiding light,
An optical recording film 3a is provided on the surface thereof.

3b is deposited. Two disk substrates 1 and 10 made of these are bonded together on their entire surfaces with an elastic adhesive 6, forming a disk structure that is vertically symmetrical about the bonding surface.

In a disk with such a configuration, the optical recording film prevents light from passing through, so a photocurable adhesive cannot be used as the elastic adhesive. Therefore, a room temperature curing adhesive such as silicone rubber or a hot melt adhesive is preferable.

Even in the case of such an adhesive, if one with a small elastic modulus is used, it will be able to absorb the strain caused by thermal expansion and swelling and will not peel off even in a high temperature and high humidity environment.

The information recording carrier having the above structure is particularly effective when its material is made of an organic polymer, examples of which include polycarbonate, acrylic resin (PMMA), vinyl chloride, and polystyrene.

Examples include polyethylene, polyester, acetate, etc.The material for the optical recording film in the present invention must be one whose light absorption coefficient or both light absorption coefficient and refractive index change upon irradiation with laser light. As, Te
There is one provided with a thin film mainly composed of 0x (X#1.0) (a mixture of TaO2 and To). These thin films include Ge16Te81Sb2S2. An amorphous thin film such as 5283 is used.

Effects of the Invention As described above, according to the present invention, it is possible to obtain a highly reliable information recording carrier that has a simple structure, does not peel off the bonded surface even with changes in the external environment, and can guarantee image quality for a long period of time. It has a great effect on

[Brief explanation of the drawing]

Figure 1 is a stop view of the information recording carrier in the conventional example;
Diagram a,? ) is a stopping surface view showing a state in which the information recording carrier in the conventional example has peeled off, FIG. 3 is a stopping surface view of the information recording carrier in the first embodiment of the present invention, and FIG. FIG. 6 is a restraining surface diagram showing an example of the absorption state of thermal strain in the first embodiment of the present invention; FIG.
The figure is a stop view of an information recording carrier in a second embodiment of the present invention. 1a... Disc base material, 1b... Disc base material, 3... Optical recording film, 2... Groove for light guide, 6... ...Elastic adhesive. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 1α Figure 2 1b loL δb Figure 3

Claims (1)

[Claims] (1) Two resin base materials each having a groove for light guide and an information recording surface on at least one of them are provided, and an adhesive having an elastic modulus smaller than that of these resin base materials is used. Information recording carrier in which both of the resin base materials are fully bonded with the information recording surface inside (2) Information recording according to claim 1, in which a light-absorbing semi-transparent film is used as the information recording surface. Carrier (3) Information recording carrier according to claim 1 or 2, using an adhesive made of a strain-absorbing elastic material as the adhesive. (4) A photocurable resin as the adhesive. The information recording carrier according to claim 1 or 2, which uses a material that changes the light absorption coefficient or both the light absorption coefficient and the refractive index by irradiation with laser light as the information recording surface. The information recording carrier according to claim 2 is used.