JPS62167635A - information carrier disk - Google Patents

Abstract

PURPOSE:To improve the adhering strength by adhering two disc bases forming a protection layer not reaching the center hole and the peripheral edge of a disc base while an adhesives is packed to the entire face so as to oppose the information medium layers to each other. CONSTITUTION:The two disc bases 1 on each side of which an information medium layer 6 and a protection layer 9 are formed are adhered to constitute a disc by packing the adhesives 4 to the entire opposed faces of the information medium layers 6 and adhering the opposed faces. In forming the protection layer 9 to the region only except the inner circumference part 7 and the outer circumference part 8 on the disc base 1, the raw material of the disc base 1 is exposed at the inner circumference part 7 and the outer circumference part 8 so as to form the region not through the information medium layer 6 or the protection layer 9 in adhering the two disc bases 1. Thus, the adhering strength is improved.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention provides at least one disk-shaped substrate having an information medium layer.
This invention relates to an information carrier disk (hereinafter simply referred to as a disk) which is made by bonding two disk-shaped substrates together.

(Prior Art) Since 1, information has been printed on a transparent substrate, such as an unrecorded recording medium layer on one side of a disc-shaped transparent substrate, or a reflective layer formed on a concave-convex bit on which a predetermined information signal has been recorded. An optical disc has been put into practical use in which information is recorded and reproduced using a laser beam from both sides of the disc, which is bonded together with an adhesive so that the surfaces of the information media layers face each other, using a disc substrate provided with a media layer. has been done. In such a double-sided disk, for example, in a disk with a so-called air sandwich structure in which the outer and inner peripheries of a disk-shaped substrate are bonded together via a spacer, it is not advisable to bond only the area without the information medium layer, that is, the outer periphery and the inner periphery. However, with a disk structure in which the entire surface between two disk substrates is filled with adhesive and then bonded together, there is a major problem with the method of curing the adhesive sandwiched between the two information medium layers. there were. In other words, when using an ultraviolet curing adhesive that has a fast curing speed and good workability, the information medium layer generally does not transmit ultraviolet rays, so the adhesive sandwiched between the information medium layers is exposed to ultraviolet rays. It was impossible to irradiate the materials with UV rays, and it was necessary to devise measures such as using an adhesive that has both ultraviolet ray curability and electrophobic curability. Furthermore, when a two-component thermal curing adhesive is used, there are problems such as slow curing speed and easy inclusion of air bubbles. There was a problem that the information medium layer could be adversely affected by contact. Furthermore, if the information medium layer is made of a thin film mainly composed of Te-based material, a portion of the laser light used for recording and reproduction will pass through. Therefore, if air bubbles, foreign matter, etc. get mixed into the adhesive that comes into contact with the information medium layer, it will cause errors.

As a method to solve such problems, for example,
As shown in Japanese Patent No. 0-20330, a disk structure as shown in FIG. 2 was proposed. In Figure 2,
1 is a disk substrate, 2 is an information medium layer formed on one side of the disk substrate 1, and 3 is a protective layer formed to cover the information medium layer 2. Two disks configured in this way The entire surface of the substrates is filled with an adhesive 4 and bonded so that the information medium layers 2 face each other. By forming the protective layer 3 in this way, it is possible to use adhesives such as a thermosetting type 1 type, a two-component temperature curing type, and a pressure curing type, which has the effect of widening the selection range of adhesives. .

(Problems to be Solved by the Invention) However, since the protective layer is formed on the entire surface of the disk substrate, it is likely to peel off from the outer peripheral edge or the center hole end face, and moisture etc. can easily enter from the end face, resulting in deterioration of the information medium layer. The problem is that it's easy to do.

Furthermore, when forming the protective layer, the material of the protective layer wraps around the outer peripheral edge of the disk substrate or the end face of the center hole, which is unsatisfactory from a practical and production standpoint.

The present invention aims to form a protective layer only on a specific portion of the disk substrate to obtain a reliable disk that does not peel off from the end face or wrap around the protective layer material.

(Means for Solving the Problems) In order to solve the above problems, the present invention has an information medium layer in an area excluding the inner periphery and outer periphery of one surface of a disk-shaped substrate,
Two disk substrates each having a protective layer formed thereon so as to cover the entire surface of the information medium layer but not to reach the center hole and outer peripheral edge of the circular substrate are placed so that the information medium layers face each other. The feature is that the entire surface is filled with adhesive and bonded together.

(Function) As described above, the present invention provides areas in which the base material of the disk substrate, in which neither the information medium layer nor the protective layer is formed, is exposed in the inner and outer peripheral areas of the surface of the disk substrate.
The bonding strength of two disk substrates can be improved, and a reliable disk that is difficult to peel off can be obtained.

Furthermore, since the protective layer is not formed on the entire surface of the disk substrate, the protective layer can be formed without wrapping around the disk substrate.

(Example) Hereinafter, one embodiment ff1l of the present invention will be described based on the drawings. In FIG. 1, the disk substrate 1 and adhesive 4 have the same structure as the conventional example shown in FIG. 2, and are indicated by the same reference numerals. 5 is a center hole that is the center of rotation of the disk substrate l. Reference numeral 6 denotes an information medium layer, which is formed in an area of one surface of the disk substrate 1 excluding the inner peripheral part 7 and the outer peripheral part 8.

A protective layer 9 is formed to cover the entire surface of the information medium layer 6 and not to reach the center hole 5 and the outer peripheral edge 10 of the disk substrate l. Two disk substrates l each having an information medium layer 6 and a protective layer 9 formed on one side in this manner are placed so that they face each other by filling the entire surface of the surface where the information medium layer 6 faces each other with an adhesive 4. The surfaces are glued together to form a disk. In the configuration shown in FIG. 1, the information medium layer 6 is made of a material containing Te as a main component.
It is a so-called phase-change recording film that records or erases by changing its optical density by heating with laser light. The protective layer 9 is coated with an organic material, and can be made of, for example, acrylic, urethane, or epoxy materials, which are transparent to laser light and do not affect the information medium N6. That's fine. In order to extend the life of the information medium N6, an epoxy material with good moisture resistance is preferred, and from the viewpoint of workability, an ultraviolet curable material is preferred. Further, if the protective layer 9 is thin, for example, when foreign matter or the like adheres to the protective layer 9, it may cause noise because the information medium N6 is semi-transparent. For this reason, it is necessary to increase the thickness to some extent. Specifically, when using a laser with a wavelength of 0.83 μm, which is 15 times or more thicker than the laser beam used for recording and reproduction, 12.
When the film thickness was 5 μn1 or more, the protective layer 9 was no longer affected by foreign matter, air bubbles, etc. On the other hand, if it is too thick, there will be problems such as weak adhesion and difficulty in curing, so the thickness of the protective N9 film should be at least 15 times the wavelength of the laser light to 50 μm.
was appropriate. When this protective layer 9 is selectively formed to have a uniform thickness by a spin code method, a spray coating method, a dip coating method, a bar code method, etc., it is possible to form the protective layer 9 with a bulge at the outer peripheral edge or a hole in the center. Appropriate application was not possible due to wraparound to the outer peripheral edge.

As a result of studying a coating method to solve these problems, we found that it was possible to form a uniform thick film layer on the area of the disk substrate 1 excluding the inner periphery 7 and outer periphery 8 by using a screen printing method. It turns out it's possible. Generally, screen printing methods tend to introduce air bubbles, but by incorporating an appropriate amount of antifoaming agent into the coating material, screen printing without air bubbles was possible.

As described above, the protective layer 9 is applied to the inner peripheral portion 7 on the disk substrate l.
By forming it only in the area excluding the outer peripheral part 8,
The inner circumferential portion 7 and the outer circumferential portion 8 expose the base material of the disk substrate 1, and when bonding two disk substrates l together, an area can be created without using the information medium layer 6 or the protection layer N9. It is possible to improve the bonding strength. Peeling is particularly likely to occur from the center hole and outer periphery of the disk, so it is important to improve the adhesion strength at these inner and outer periphery areas. The effect is great.

Note that since the adhesive 4 used to bond the two disk substrates l covers the information medium layer 6 with the protective layer 9, it is a thermosetting type adhesive.
The range of selection is wide, such as a two-component thermal curing type and a heat-pressure curing type, and furthermore, it is possible to bond with adhesive tapes.

Furthermore, although this embodiment has been described with a structure in which both of the two substrates have an information medium layer, it is also possible to have an information medium layer on only one substrate and use the other substrate simply as a protection plate. be. Furthermore, although this embodiment has been described as an example of a phase-change type erasing disk, it can also be applied to a magneto-optical disk or a write-once type disk in which recording, reproduction, and erasing are performed using the heat and magnetic field of a laser beam.

(Effects of the Invention) The present invention forms an information medium layer in an area excluding the inside of a circle and the outer periphery of one surface of a disk substrate, and applies a protective layer covering the entire surface of the information medium layer and extending to the center hole and the outer edge of the disk substrate. By forming the protective layer so that it does not reach the center hole of the disk substrate, the bonding strength of the two disk substrates can be improved. It is something. Furthermore, by covering the information medium layer with a layer, the adhesive can be used in a wider range of applications, making it practical and suitable for mass production.

[Brief explanation of drawings]

FIG. 1 is a sectional view of an information carrier disk according to an embodiment of the present invention, and FIG. 2 is a sectional view of a conventional information carrier disk. DESCRIPTION OF SYMBOLS 1... Disk substrate, 2, 6... Information medium layer, 3°9... Protective layer, 4... Adhesive. Fig. 1 1 ° Disc substrate, 4...Kototogi 5...Zonkue 2"° product sum 4φji 3...Momogo layer

Claims (4)

[Claims] (1) having an information medium layer in an area excluding the inner periphery and outer periphery of one surface of the disk-shaped substrate, covering the entire surface of this information medium layer;
and two disk substrates on which a protective layer is formed so as not to reach the center hole and outer peripheral edge of the disk-shaped substrate,
An information carrier disk characterized in that the entire surface is filled with an adhesive and bonded together so that the information medium layers face each other. (2) Information as set forth in claim (1), characterized in that the thickness of the protective layer is 15 times or more the wavelength of laser light for recording and reproducing information on the information medium layer. carrier disc. (3) The protective layer is made of an ultraviolet curable organic material.
2) Information carrier disk described in section 2). (4) Information according to any one of claims (1), (2), or (3), characterized in that the protective layer is selectively formed by a screen printing method. carrier disc.