JPS615452A - Information recording carrier - Google Patents

Abstract

PURPOSE:To prevent deterioration of a recording film, by joining a resin-based material equipped with a groove for guiding light and optical recording film with another resin-based material by using a bonding agent, whose elastic modulus is smaller than that of the resin-based material, over the entire surface and further applying a reinforcing bonding agent to the innermost and outermost peripheries of the joined part. CONSTITUTION:A groove 2 for guiding light is provided in a disk base material 1a made of polycarbonate resin and an optical recording film 3 is deposited on the surface of the groove 2. The disk base material 1a thus prepared is joined with another disk base material 1b made of similar polycarbonate resin over the entire surface with the optical recording film 3 inward by using a photosetting type elastic bonding agent 6. The innermost and outermost peripheries of the joined part is further bonded and sealed with an epoxy resin 7. A bonding agent having an elastic modulus which is smaller than those of the base materials 1a and 1b is used for the bonding agent 6. Therefore, no exfoliation occurs at the joined part and disk deformation can be minimized even when the external environment changes and, as a result, deterioration of the recording film can be prevented for a long period.

Description

DETAILED DESCRIPTION OF THE INVENTION FIELD OF INDUSTRIAL APPLICATION The present invention relates to a disc-shaped information recording carrier used in optical recording or reproduction 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.

Recently, in the information society, rationalization of office automation, laboratory automation, etc. has become important, and in order to meet these demands, additional storage type disks that allow users to freely record and play back are ideal. It is.

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 conventionally used disks will be explained with reference to the drawings. 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 is bonded over its entire surface to a disk base material 1b made of polycarbonate resin using a photocurable adhesive 4.

Particularly when such disk base materials 1a and 1b are manufactured by injection molding, they often contain internal stress and tend to generate thermal strain in a high temperature and high humidity environment. Therefore, if the adhesive 4 that joins the two disc base materials has high rigidity, for example, as shown in FIGS.
A minute peeling esa, 6b 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 itself by causing minute peeling. These minute peels sa and 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.

This type of micro-separation is initially under a vacuum condition, but when ventilation occurs between the outermost or innermost part of the disk that is in contact with the outside air, the outside air can instantly be drawn into the delamination area. become.

Therefore, if the outside air environment is hot and humid,
1j, in the case of materials that are easily affected by humidity, it is thought that oxidation occurs and deterioration is accelerated.

As described above, 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, which poses a serious problem in terms of disk reliability. Even if the peeling does not expand and remains a minute peel, it will not be completely 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 the bonding surface even in a high temperature and high humidity environment and minimizes deterioration of the recording film. It is something.

Structure of the Invention The present invention involves bonding two disk substrates each having an optical guiding groove and an optical recording film on at least one side using a strain-absorbing adhesive with a small elastic modulus, and also By reinforcing the innermost and outermost peripheries with epoxy resin, it is possible to prevent peeling at the bonding surface and to manufacture a disk with high reliability for the optical recording film.

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 those in FIGS. 1 and 2 will be described with the same reference numerals. 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 is made of a disk base material 1b made of polycarbonate resin and a photocurable elastic adhesive 6.
(The entire surface is bonded with the optical recording film 3 facing inside. Furthermore, the innermost and outermost peripheries of the bonded portion are adhesively sealed with epoxy resin 7.

In order to reduce costs, it is necessary to manufacture the optical guide groove 2 integrally with the disk base material by injection molding. 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 elastic adhesive 6 itself has elasticity, the disk base material 1a
Even if a minute strain occurs, the elastic adhesive 6 moves in a manner that follows the strain, as shown in FIG. 4, and no peeling occurs.

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 reaches high temperatures, the different amounts of elongation generate stress, and adhesives with high rigidity tend 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 strain by using
Occurrence of peeling can be prevented.

For example, the elongation 8 due to thermal expansion and swelling of the disk base material shown in FIG. 5 is different from the elongation 9 due to thermal expansion and swelling of the elastic adhesive 6.
, the stress difference due to the difference in the amount of elongation is stored in the elastic adhesive 6 as an internal stress 10. Since the elastic modulus of the elastic adhesive is small, even if the deformation is large, the internal stress 10 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 if the elastic coefficient EKp/- of the elastic adhesive is small, α=Eε Due to the relationship (α: internal stress, ε: strain), the internal stress is also reduced, and it is relatively easy to use an elastic adhesive that has adhesive strength that can withstand this stress.

Furthermore, in this embodiment, the inner and outer peripheries of the joint are reinforced with epoxy resin 7, so the elastic adhesive prevents minute peeling at the joint surface and prevents deformation of the entire disk. The epoxy resin plays a role in keeping it to a minimum. If only elastic adhesive is used, it can follow minute distortions, but it also easily follows relatively large deformations of the entire disk.
1 boxy resin is used.

Further, the effects of thermal expansion and swelling occur 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 in this example include a longitudinal elastic modulus, a transverse elastic modulus, 9, and a bending elastic modulus, and it can be said that the smaller these values are, the better the elasticity is. According to experiments, these elastic modulus AKg/
- as long as 10 Ky/-≦A≦20QK/mj, 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 found that the greater the difference between the two, the greater the effect. The elastic modulus of the reinforcing adhesive may be approximately the same as that of the disk base material, and types of this adhesive include, in addition to epoxy resins, epoxy acrylate resins, acrylic resins, and the like.

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, provided with grooves 2a and 2b for guiding light, and an optical recording film 3a on the surface thereof.

3b is deposited. The two disk base materials 1 and 11 made of these are fully bonded with an elastic adhesive 6, and the innermost and outermost peripheries of the bonded surfaces are adhesively sealed with an epoxy resin 7. It is symmetrical.

In a disk having such a configuration, a photocurable adhesive cannot be used as the elastic adhesive 6 because the optical recording film prevents the transmission of light. 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, the strain caused by thermal expansion and swelling can be absorbed, and peeling will not occur even in a high temperature and high humidity environment.

Furthermore, the same effect as in the first embodiment can be obtained with respect to the deformation of the entire disk using the epoxy resin.

The information recording carrier having the above structure is particularly effective when the material thereof is made of an organic polymer; for example,
In addition to polycarbonate and acrylic resin (PMMA), vinyl chloride and polystyrene.

There are polyethylene, polyester, acetate, etc.

The material of the optical recording film in the present invention must be one whose light absorption coefficient or both the light absorption coefficient and the refractive index change upon irradiation with laser light.
0x (x#1.0) (Teo2 and T.

Some products have a thin film mainly composed of a mixture of

These thin films include Ge1. Te81Sb2S2.
An amorphous thin film such as 5283 is used.

Effects of the Invention As described above, the present invention has a simple structure, has no peeling of the joint surface even with changes in the external environment, has little disk deformation, and is reliable enough to guarantee long-term image quality. This has a great effect in obtaining a high quality information recording carrier.

[Brief explanation of drawings]

The first factor is the cross-sectional front view of the information recording carrier in the conventional example;
Figures a and b are cross-sectional front views showing a state in which an information recording carrier in a conventional example has peeled off, Figure 3 is a cross-sectional front view of an information recording carrier in a first embodiment of the present invention, and Figure 4 is a cross-sectional front view of the information recording carrier in the first embodiment of the present invention. FIG. 6 is a sectional front view showing an example of the absorption state of thermal strain in the first embodiment of the present invention, and FIG. 6 is a sectional front view showing the absorption state of distortion due to thermal expansion and swelling in the first embodiment of the present invention. , FIG. 6 is a sectional front view of an information recording carrier in a second embodiment of the present invention. 1a... Disc base material, 1b... Disc base material, 2... Groove for light guide, 3......
Optical recording film, 6... Elastic adhesive, 7... Reinforcing adhesive. Name of agent: Patent attorney Toshio Nakao and 1 other person +1 Figure 1 Figure 2 Figure 3

Claims (6)

[Claims] (1) Two resin base materials each having a groove for light guide and an information recording surface on at least one side are provided, and the information recording surface is bonded to the resin base material using an adhesive having an elastic modulus smaller than that of these resin base materials. An information recording carrier in which both of the resin base materials are fully bonded on the inside, and a reinforcing adhesive is applied to the innermost and outermost peripheries of this bonded portion. (2) The information recording carrier according to claim 1, which uses a light-absorbing semitransparent film as the information recording surface. (3) The information recording carrier according to claim 1 or 2, wherein an adhesive made of a strain-absorbing elastic material is used as the adhesive. (4) The information recording carrier according to claim 1 or 2, wherein a photocurable resin is used as the adhesive. (5) The information recording carrier according to claim 1 or 2, wherein an epoxy resin is used as the reinforcing adhesive. (6) The information recording carrier according to claim 2, wherein the information recording surface is made of a material whose light absorption coefficient or both the light absorption coefficient and the refractive index change upon irradiation with laser light.