JPH0812727B2 - Optical information recording medium - Google Patents

Description

The present invention relates to improvements in optical information recording media.

Conventionally, in this optical information recording medium, as shown in FIGS. 1 (a) and 1 (b), holes 3 and 4 are formed in the center of two disk-shaped transparent substrates 1 and 2, and an intermediate circumference thereof is formed. The information recording layers 5 and 6 are formed on the areas, and laser light is irradiated from the transparent substrates 1 and 2 side to make holes of about 1 μm in the information recording layers 5 and 6, and whether or not there are holes. The information is reproduced by the change in reflectance due to.

And, this optical information recording medium has information recording layers 5, 6
2 to prevent deterioration due to outside air, especially humidity
In the inner circumference area and the outer circumference area of the disk-shaped transparent substrates 1 and 2,
Insert the inner and outer circumferential plates 7 and 8 as spacer materials,
Adhesives 9, 10, 11, 12 are interposed between the upper and lower surfaces and the two disk-shaped transparent substrates 1 and 2 to form two disk-shaped transparent substrates 1 and 2.
Are joined together, and the information recording layers 5 and 6 are structured to be shielded from the outside air.

However, in the conventional optical information recording medium, since it is difficult to make the thickness of the adhesives 9 to 12 uniform,
The parallelism of the transparent substrates 1 and 2 is unavoidably reduced, and the thickness of the inner and outer peripheral plates 7 and 8 as spacers is 0.5 mm.
If you want to make it thinner, it becomes difficult to handle it,
There was a drawback that workability was lowered.

The present invention has been made in order to eliminate the above-mentioned drawbacks, and prevents deterioration of the information recording layer by a simple manufacturing method, and keeps the distance between two disk-shaped transparent substrates high in parallelism. It is an object of the present invention to provide an optical information recording medium held in.

In order to maintain a high parallelism between the two disk-shaped transparent substrates, which is one of the above-mentioned objects, the present inventor simply needs to provide a space between the transparent substrates with a diameter substantially equal to this distance. It is not enough to interpose a spherical body, and it is necessary to secure good dispersibility of the spherical body and good dischargeability of the adhesive existing between the transparent substrate and the spherical body. Reached In order to improve the dispersibility and discharge property, the adhesive naturally needs to have high fluidity. However, when the fluidity of the adhesive is improved, the adhesive flows out to the information recording layer. Therefore, a new problem occurs that the information recording layer is deteriorated. Therefore, the present inventor, after earnestly researching, first focused on the characteristics of the adhesive having thixotropy as a foothold for comprehensively solving the two technical problems having such a trade-off relationship. What is this thixotropic property?
"Characteristics in which the apparent viscosity decreases as the flow velocity increases". However, the thixotropy itself of this adhesive does not immediately solve the technical problem. The present inventor further advances, by organically bonding the adhesive having a thixotropic property and the spherical body, the purpose is to draw out the changing fluidity peculiar to the adhesive having a thixotropic property. As a result, it has been found for the first time that the above technical problems can be solved.

The optical information recording medium of the present invention is based on such knowledge, and has a hole in the center, and an inner circumferential region, an intermediate circumferential region, and an inner circumferential region sequentially arranged in the radial direction from the hole, and Two disk-shaped transparent substrates each having an outer circumferential area and having an information recording layer formed in the intermediate circumferential area are spaced apart and face each other so that the information recording layers face each other. Of the two transparent substrates facing each other in the optical information recording medium in which the two disk-shaped transparent substrates are joined by interposing an adhesive in each gap between the inner circumferential region and the outer circumferential region. The adhesive intervening in the respective gaps in the circumferential region and the outer circumferential region is separated from the information recording layer, and the adhesive is selected as a thixotropic adhesive, and the two disc-shaped A plurality of spherical bodies having a diameter substantially equal to the distance between the transparent substrates are connected to each other. It is characterized by being dispersed in a binder.

In the present invention, by dispersing the spheres in the thixotropic adhesive, the adhesive receives an external force from the moving spheres to have high flowability, and as a result, the spheres are smoothly and substantially used as the adhesive. It can be dispersed uniformly.

Further, even when the adhesive existing between the transparent substrate and the spherical body is discharged, the adhesive receives external force from both the spherical body and the disk-shaped transparent substrate to increase the fluidity. It can be discharged smoothly and easily. As a result, the adhesive does not remain in the gap between the disk-shaped transparent substrate and the spherical body, so that the distance between the two disk-shaped transparent substrates can be made substantially equal to the diameter of the spherical body.

Further, after the thixotropic adhesive is interposed, the fluidity of the adhesive decreases, so that the adhesive can be prevented from flowing out to the information recording layer.

An embodiment of the optical information recording medium of the present invention will be described below with reference to FIG.

2 (a) and 2 (b) are a sectional view and an enlarged partial sectional view of an embodiment of the optical information recording medium according to the present invention.
The external appearance is similar to that shown in FIG. 1A, and the same functional portions as those shown in FIG. 1 are designated by the same reference numerals.

The transparent substrates 1 and 2 of this example are circular plates made of soda lime glass having a diameter of 300 mm and a thickness of 1.2 mm, and a diameter of 35 mm at the center thereof.
Holes 3 and 4 are opened. Further, each of the transparent substrate 1 and the transparent substrate 2 has an inner circumferential region, an intermediate circumferential region, and an outer circumferential region sequentially arranged in the radial direction from the holes 3 and 4. The width of each of the inner peripheral region and the outer peripheral region is 2 mm. Information recording layers 5 and 6 made of a tellurium film (film thickness of 200 to 300 Å) are formed on the intermediate circumferential regions of the transparent substrates 1 and 2, and the two information recording layers 5 and 6 face each other. Transparent substrates 1 and 2 are arranged with their centers aligned.

These two transparent substrates 1 and 2 have adhesives 17 and 18 interposed between the facing inner circumferential regions and adhesives 19 and 20 between the facing outer circumferential regions. Are joined by interposing. Each of the adhesives 17 to 20 is provided separately from the information recording layer 5 or 6 as illustrated.

The adhesives 17 to 20 are thixotropic (thixotropic).
Adhesive (flexible type UV curable resin CV7005 manufactured by Matsushita Electric Works, Ltd.) is used.
Each of No. 20 to No. 20 is composed of a glass body, and spherical bodies 13 to 16 each having a diameter of 100 μm are dispersed substantially uniformly. In the case of one cross-section when the outer circumference is viewed from the holes 3 and 4, this dispersion state is shown in the drawings such that four pieces are uniformly arranged in each of the inner circumferential area and the outer circumferential area. In this example, the region width is 2 mm, and the diameter of the spherical bodies 13 to 16 (100 μm
Since it is 20 times larger than m), it is actually several in one section.
Dozens of them are unevenly distributed. Transparent substrate 1 and transparent substrate 2
The substrate spacing t (see FIG. 2) is equal to the diameter of the spherical bodies 13 to 16 (even if there is an error of ± 20% in the diameter dimension, the plurality of spherical bodies are dispersed. It is practically determined by the diameter near the upper limit (± 20%).

In the optical information recording medium of this embodiment, thixotropic adhesives are used as the adhesives 17 to 20 for joining the two transparent substrates 1 and 2. Therefore, this adhesive 17-20
The following effects can be obtained due to the cooperation of the spherical bodies 13 to 16.

First, when the spherical bodies 13-16 are dispersed in the adhesives 17-20, the movement of the spherical bodies 13-16 increases the flow rate of the adhesives 17-20, and as a result, the viscosity of the adhesives 17-20 is increased. The spheres 13 to 16 have a high fluidity and the adhesive 17 to
Dispersed smoothly and evenly in 20. When the transparent substrate 1 and the transparent substrate 2 are joined together, both the transparent substrates 1 and 2 are
The spherical bodies 13 to 16 are in contact with each other so that the substrate distance t is equal to the spherical body 13
The spherical substrates 13 to 16 are sandwiched and pressed by the transparent substrates 1 and 2 so as to have a diameter substantially equal to that of the transparent substrate 1.
It is necessary to drain the adhesives 17-20 between Nos. 2 and 2 and the spheres 13-16. Even when the adhesive is discharged, since the adhesive has thixotropy, the flow rate of the adhesive in the gap portion that is subjected to an external force by the transparent substrate and the spherical body increases, and as a result, the viscosity decreases. Therefore, the adhesive between the transparent substrate and the spherical body can be smoothly discharged easily.

As described above, the transparent substrate 1 and the transparent substrate 2 are dispersed by substantially uniformly dispersing the spherical body in the adhesive and easily and smoothly discharging the adhesive in the gap between the transparent substrate and the spherical body. It is possible to join and to face and with high parallelism.

Next, since the curing agent contained in the adhesives 17 to 20 generally deteriorates the information recording layer, as described above, the adhesive 17
.About.20 must be provided at positions separated from the information recording layers 5 and 6, respectively. In the optical information recording medium of this embodiment, the adhesives 17 to 20 in which the spherical bodies 13 to 16 are uniformly dispersed are used.
After the adhesive is provided at a position separated from the recording layers 5 and 6
17 to 20 are released from external force and the flow velocity decreases, so that the viscosity increases and the fluidity deteriorates. Therefore,
Since it is possible to prevent the adhesive from flowing out to the information recording layer where the adhesive should not adhere, it is possible to prevent deterioration of the recording layer.

Next, regarding the workability when joining the two transparent substrates 1 and 2, the plurality of spherical bodies 13 to 16 together with the adhesives 17 to 20 on the inner cylindrical area and the outer circumferential area as described above. Due to the arrangement, even if the diameter dimension of the spherical bodies 13 to 16 is reduced, it can be performed extremely easily as compared with the conventional thin plate-shaped space member.

The present invention is not limited to the substances listed in the above examples,
The transparent substrate material may be plastic, and the spherical material may be plastic or metal. As the thixotropic adhesive, for example, in addition to the adhesive used in the above-mentioned embodiment, for example, a two-component epoxy adhesive T-53 which is cured at room temperature.
0 (manufactured by Amicon Co., Ltd.) can be used.

According to the optical information recording medium of the present invention, since the spherical adhesive having a diameter substantially equal to the distance between the substrates is dispersed in the thixotropic adhesive that bonds the two transparent substrates, the two transparent substrates Can be joined while maintaining high parallelism.

As a result, since the optical information recording medium can be stably rotated, it is possible to prevent deterioration of information recording and reading accuracy.

Since the adhesive is separated from the information recording layer,
It is also possible to prevent deterioration of the information recording layer.

Further, the optical information recording medium having such a structure can be manufactured with good workability.

[Brief description of drawings]

FIG. 1 shows a conventional optical information recording medium, which is shown in FIG.
Is a perspective view showing its appearance, and FIG.
It is sectional drawing of the XX line part of FIG. FIG. 2 shows an optical information recording medium according to the present invention. FIG. 2A is a sectional view similar to FIG. 1B and FIG. 2B is a partially enlarged view. 1,2 …… Disc-shaped transparent substrate, 3, 4 …… Hole, 5, 6 …… Information recording layer, 13, 14, 15, 16 …… Spherical body, 17, 18, 19, 20 …… Adhesive

Claims (1)

[Claims] 1. An information recording layer is formed in the middle circumferential area, wherein a hole is provided in the center, and an inner circumferential area, an intermediate circumferential area, and an outer circumferential area are sequentially arranged from the hole in the radial direction. The two disk-shaped transparent substrates are arranged so as to be spaced apart from each other so that the information recording layers face each other, and an adhesive is applied to each gap between the facing inner and outer circumferential regions. In the optical information recording medium in which the two disk-shaped transparent substrates are joined by interposing, an adhesive agent intervening in each gap between the inner circumferential region and the outer circumferential region of the two transparent substrates facing each other. Is separated from the information recording layer, the adhesive is selected as a thixotropic adhesive, and a plurality of spherical bodies having a diameter substantially equal to the distance between the two disk-shaped transparent substrates are bonded to each other. An optical information recording medium characterized by being dispersed in an agent.