JP2000215518A - Optical information medium and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To ensure necessary sticking strength of a disk by using an adhesive, having a relatively low viscosity to form a dense adhesive layer with few included fine bubbles and by enabling uniform rapid spreading of the adhesive to form the adhesive layer into a prescribed thickness. SOLUTION: This optical information medium has 1st and 2nd substrates 1, 5 stuck together, and at least the substrate 1 has a recorded signal or a region in which a signal can be recorded. The optical information medium has ruggedness 15 in the radial direction at the stuck surface of at least one of the substrates 1, 5 and an adhesive layer 11, which mutually bonds the 1st and 2nd substrates 1, 5 together at the stuck surface having the ruggedness 15. The thickness of the adhesive layer 11 is adjusted to 15-50 μm for ensuring the necessary sticking strength of the substrates 1, 5.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an optical information medium on which optically reproducible information can be recorded and a method for manufacturing the same.
More particularly, the present invention relates to an optical information medium having a form in which two substrates are bonded, uniformly spreading an adhesive between the two substrates, and bonding these substrates, and a method of manufacturing the same.

[0002]

2. Description of the Related Art With the recent development and commercialization of short wavelength lasers, DVDs (Digi
With the standardization of the tal versatile disc standard, its practical use is progressing. In this DVD, a data recording area is set on at least one main surface, pits serving as information recording means are formed in the data recording area, and a reflective layer made of a metal film is formed thereon.

[0003] In the DVD, a different standard is defined for higher density as compared with a CD (Compact Disc) which is a standard of an optical information medium at present. For example,
In an optical pickup, a wavelength of 630 nm to 670
The use of a short wavelength red laser of nm
A is to use a high aperture ratio objective lens of 0.6. In order to cope with the warpage of the disk, a disk having a thickness of about 0.6 mm, which is about half the thickness of a CD, has been adopted. However, the disk thickness of 1.2mm C
In order to ensure dimensional compatibility with D, the two disks are bonded together. According to the DVD standard, it is standardized that a maximum recording capacity of about 4.7 GB and an average of about 133 minutes of video and audio are recorded on a single disk.

In the standardization of the DVD standard, CD-
Similar to the relationship between ROM and CD-R or CD-RW,
Initially, both a read-only optical information medium and a recordable optical information medium were assumed. However, the initial standardization is limited to DVDs for reproduction, such as DVD-Video for video and DVD-ROM for recording computer data, and standardization is postponed for recordable DVDs. Under such a background, development of an optical information medium capable of recording at a high density with a maximum recording capacity of 4.7 GB on one disc and a recording technique thereof are desired.

[0005] DVD which is a high-density recording medium as described above
As described above, in order to ensure dimensional compatibility with a CD having a disc thickness of 1.2 mm, two discs are bonded together. An adhesive is used for bonding the disks. As an adhesive,
For example, an ultraviolet curable resin-based resin is used, and its viscosity before being cured is about 500 cps.

[0006] In bonding two disks, it is necessary to spread the adhesive uniformly between the bonded surfaces and then cure the adhesive. As a means for spreading the adhesive between the disks, for example, an adhesive is applied to the inner peripheral side of at least one of the disks,
Means are used in which two disks are superimposed, the superimposed disks are rotated at a high speed, and the centrifugal force is used to spread the adhesive between the disks in the outer circumferential direction.

[Problems to be solved by the invention]

As described above, 500 cps as an adhesive
Since the front and rear adhesives having a relatively high viscosity are used, the adhesive is not easily spread even if the overlapped disks are sufficiently rotated. In addition, since the viscosity of the adhesive is large, air bubbles mixed in the adhesive are trapped in the adhesive, and the air bubbles do not easily come out, so that fine particles are formed in the adhesive layer formed by curing the adhesive. Air bubbles remain. For this reason,
There is a problem that the adhesive layer becomes coarse and dense, resulting in a decrease in adhesive strength and an influence on the pit shape.

[0008] In order to solve such a problem, it has been studied to use an adhesive having a lower viscosity in order to speed up the development of the adhesive and to reduce air bubble containment. However, if the viscosity of the adhesive is lower than about 500 cps, the fluidity of the adhesive is too high during centrifugal development, so that the adhesive is shaken off from between the discs and finally formed when the adhesive is cured. The resulting adhesive layer is too thin. For this reason, there is a problem that necessary adhesive strength cannot be secured.

In the present invention, in view of the problem of such an optical information medium bonding means having a structure in which two disks are bonded, the first object is to have a structure in which two disks are bonded. It is an object of the present invention to obtain a dense adhesive layer by using an adhesive having a relatively low viscosity in an optical information medium, suppressing entry of fine bubbles into the adhesive layer, and the like. Further, a second object of the present invention is to allow the adhesive to be spread evenly and quickly when the adhesive is spread between the discs, and to obtain an adhesive layer having a predetermined film thickness so that the necessary disc can be formed. The purpose is to secure the bonding strength.

[0010]

According to the present invention, in order to achieve the above-mentioned object, by using an adhesive having a low viscosity, it is possible to eliminate the trapping of fine bubbles in the adhesive layer 11 and to achieve a high speed. This enables uniform development of the adhesive. Moreover, in order to obtain the necessary adhesive strength of the adhesive layer 11, at least one of the bonding surfaces of the substrates 1 and 5 is provided with irregularities 15 and 16 that repeat concave and convex in the radial direction, and the thickness of the adhesive layer 11 is reduced. Be able to secure.

That is, the optical information medium according to the present invention has the first and second substrates 1 and 5 bonded together and a signal recorded on at least one of the substrates 1 or an area in which the signal can be recorded. And at least one of the first substrate 1 and the second substrate 5 to be bonded to each other.
15 and 16 which are formed on the bonding surface and repeat the irregularities in the radial direction, and an adhesive layer 11 in which the first substrate 1 and the second substrate 5 are bonded to each other on the bonding surface having the irregularities 15 and 16. And

The irregularities 15, 16 of the first and second substrates 1, 5
Is usually helical. The groove width of the irregularities 15, 16 of the first and second substrates 1, 5 is 0.37 ±
0.2 μm. The adhesive layer 11 has a uniform film thickness, and by setting the film thickness to 10 to 50 μm, required bonding strength between the substrates 1 and 5 can be secured.

A method for manufacturing such an optical information medium is as follows.
A step of preparing a first substrate 1 and a second substrate 5 having at least one of the substrates 1 and 5 having irregularities 15 and 16 that repeat irregularities in the radial direction on a bonding surface of the first and second substrates; A step of applying an adhesive to at least one of the bonding surfaces of the first and second substrates, a step of overlapping the bonding surfaces of the first substrate 1 and the second substrate 5, and a first substrate 1 and a second substrate 5, a step of spreading the adhesive between the bonding surfaces on the bonding surfaces, and curing the expanded adhesive to form an adhesive layer 11
Forming a step. In the step of developing the adhesive between the first and second substrates 1 and 5, the adhesive is usually centrifugally applied by rotating the first and second substrates 1 and 5 which are superimposed. expand. At this time, an adhesive having a relatively low viscosity of 80 to 250 cps when uncured can be used.

In such an optical information medium and a method of manufacturing the same, when the adhesive is sandwiched between the first and second substrates 1 and 5 and developed in the radial direction thereof, the substrates 1 and 5 are bonded together. The flow resistance of the adhesive increases due to the irregularities 15 and 16 formed on the surface. For this reason, even if an adhesive having a relatively small viscosity is used, the amount of the adhesive to be shaken out does not become excessive, and the thickness of the adhesive layer 11 necessary for obtaining a required adhesive force can be ensured. it can. That is, since the irregularities 15 and 16 formed on the bonding surfaces of the substrates 1 and 5 repeat the irregularities in the radial direction of the substrates 1 and 5, it gives the uncured adhesive flow resistance at the time of development, and To prevent spills.

On the other hand, the use of an adhesive having a relatively low viscosity reduces the trapping of air bubbles inside the adhesive and facilitates defoaming, so that the adhesive formed by curing the adhesive can be used. The layer 11 becomes dense. Thereby, higher adhesive strength can be obtained with the thin adhesive layer 11. Further, since the adhesive has a small viscosity, the adhesive that has been shaken off during centrifugal development can be easily reused, and the recycling thereof can be easily realized. Furthermore, when the optical information medium becomes unnecessary, the substrates 1 and 5 are separated, and when the substrates 1 and 5 and the reflective layer formed thereon are reused as resources, the removal of the adhesive becomes easy, Resources can be easily reused.

The viscosity of the uncured adhesive is 80.
The use of the substrate 1, the substrate 1,
This is for obtaining the optimal adhesive layer 11 having a thickness of 10 to 50 μm by the unevenness of the bonding surface of No. 5. If the viscosity of the adhesive is too low, the required film thickness of the adhesive layer 11 cannot be secured,
The bonding strength of the substrates 1 and 5 decreases. Conversely, if the viscosity of the adhesive is too high, the thickness of the adhesive layer 11 will be excessive. 10
The thickness of the adhesive layer 11 of ~ 50 μm is for securing a required adhesive strength of the bonded substrates 1 and 5. There is no increase. Rather, as a result of an excessively large film thickness, the recycling of the adhesive is hindered, and it becomes difficult to remove the adhesive during recycling as a resource of the optical information medium.

[0017]

Embodiments of the present invention will now be described specifically and in detail with reference to the drawings. As an example of the optical information medium according to the present invention, an example of a write-once optical information medium having a single-sided recording / reproducing structure by double-sided bonding is shown in FIGS. The first substrate 1 is a transparent disk-shaped substrate having a center hole 4 in the center. The substrate 1 is generally made by injection molding a transparent resin such as polycarbonate and polymethyl methacrylate (PMMA).

A clamping area is set outside the center hole 4 on one side of the light-transmitting substrate 1, and the outer peripheral side of the clamping area is a data recording area. A tracking guide 3 composed of a spiral groove is formed in a data recording area of the substrate 1. The pitch of this tracking guide 3 is
0.74 μm is standard.

Further, as shown in FIGS.
The recording layer 12 is formed on the main surface of the data recording area. For example, an organic dye or the like is applied by a method such as a spin coating method, and the recording layer 12 is formed. This recording layer 12
A reflective layer 13 made of a metal film of gold, aluminum, silver, copper or the like or an alloy film thereof is formed thereon. Further, a protective film 14 such as an ultraviolet curable resin is formed on the reflective layer 13.

As shown in FIGS. 1 to 3, another second substrate 5 is prepared in addition to the substrate 1. The second substrate 5 is of the same size and made of the same material as the substrate 1, but has a recording layer 1 such as the substrate 1 on its main surface.
2. No reflective layer 13 is provided. Needless to say, the recording layer 12 and the reflection layer 13 can be provided on the other substrate 5 as well as the substrate 1.

On the bonding surface of the substrate 5, irregularities 15 as shown in FIGS. 2 and 3 are formed. The concave and convex grooves are the same as those for forming the tracking guide 3 of the first substrate 1, and are spirally formed on the bonding surface of the substrate 5. The pitch of the groove is
0.74 μm is standard. The groove width, specifically, the half width at half the depth of the groove is 0.37 ± 0.2 μm.
m.

Next, these two substrates 1 and 5 are bonded together. FIG. 7 is a view showing a step of bonding the two substrates 1 and 5, and an example of the step of bonding the substrates will be described with reference to FIG. As shown in FIG. 7, a turntable 22 on which the substrate 1 is placed is provided on a work table 21.
The worktable 21 rotates intermittently, and a plurality of processes are sequentially performed at a work station set at the stop position of each turntable 22.

A center pin 23 projects from the center of the upper surface of the turntable 22, and the substrate 1 is positioned with the center pin 23 inserted into the center hole 4 of the substrates 1 and 5 (see FIGS. 1 and 2). . Turntable 22
There is a slight dimensional margin between the center pin 23 and the center holes 4 of the substrates 1 and 5, so-called play, thereby making it easier for the center pins 23 to be inserted into the center holes 4 of the substrates 1 and 5. Turntable 22
A spindle (not shown) is provided concentrically with the center pin 23 from below the lower surface, and the table 22 is rotated by a drive motor via the spindle.

First, the work table 21 stops, and FIG.
As shown in (a), when the turntable 22 stops at the first workstation, the turntable 2
One substrate 1 is placed on 2. For example, the substrate 1 is placed on the turntable 22 using a manipulator 27 using vacuum suction means or the like. At this time, the center pin 23 on the tar table 22 is
(See FIGS. 1 and 2), and the substrate 1 is positioned.

Next, when the work table 21 rotates intermittently by one step, the turn table 22 moves to the work station for performing the adhesive application step shown in FIG. 7B, and stops there. Here, if the turntable 21 is rotated at a low speed, an adhesive a such as an ultraviolet curable resin is applied around the center hole 4 of the substrate 1 on the tar table 22 using the dispenser 25.

Next, the worktable 21 rotates one step intermittently, and the turntable 22 moves to the next work station shown in FIG. In this position,
Another substrate 5 is placed on the substrate 1 on the turntable 22, and the bonding surfaces of the substrates 1 and 2 are overlapped. For example, the substrate 5 is placed on the substrate 1 by using a manipulator using a vacuum suction unit or the like in the same manner as the substrate 1.

When the substrate 5 is placed on the substrate 1, the substrate 1
Is applied between the bonding surfaces of the substrates 1 and 5, and spreads in the gap. Further, the turntable 22 is rotated at high speed, the adhesive is spread on the outer peripheral side of the substrates 1 and 5 by centrifugal force, and excess adhesive is shaken off from between the substrates 1 and 5. Thereby, between the substrate 1 and the substrate 5,
The adhesive of the minimum thickness required for their adhesion is left. In this state, the adhesive is not cured, and the substrates 1 and 5 are not fixed.

Next, the worktable 21 rotates one step intermittently, and the turntable 22 moves to the next work station shown in FIG. At this position, the ultraviolet ray is applied to the adhesive between the substrates 1 and 5 through the substrate 5 by the ultraviolet lamp 28. Thereby, the adhesive is cured, and the substrates 1 and 5 are fixed to each other. In the above-described example, the substrate 1 is first placed on the turntable 22. On the contrary, a so-called dummy substrate 5 having no recording layer 12 and the reflective layer 14 is first placed on the tar table 22, The substrate 1 having the recording layer 12 and the reflective layer 14 can be placed thereon and bonded.

In the present invention, an adhesive having a low viscosity of 80 to 250 cps is used in the step of bonding the substrates 1 and 5 as described above. When such an adhesive having a low comparative point viscosity is sandwiched between the first and second substrates 1 and 5 and developed in the radial direction, the unevenness 15 formed on the bonding surface of the substrate 5 causes As a result, the flow resistance of the adhesive is increased, and a necessary amount of the adhesive can be retained between the substrates 1 and 5. For this reason, it is possible to secure a thickness of 10 to 50 μm of the adhesive layer 11 necessary for obtaining a required adhesive force.

As described above, the use of an adhesive having a relatively low viscosity reduces the trapping of air bubbles inside the adhesive and facilitates defoaming from the adhesive.
The adhesive layer 11 becomes dense. Thereby, the thin adhesive layer 11
However, high adhesive strength can be obtained. Further, when the substrates 1 and 5 of the used optical information medium are separated and the adhesive is removed from the bonding surfaces of the substrates 1 and 5, the removal is facilitated.

FIG. 4 is a schematic sectional view showing a state in which the bonding surfaces of substrates 1 and 5 are bonded in another example of the optical information medium according to the present invention. In the above-described example, the protective layer 14 made of an ultraviolet curable resin was provided on the reflective layer 13 on the substrate 1 side, and the protective layer 14 was substantially flat. In contrast,
In the example shown in FIG.
6 are provided. The pitch of the unevenness 16 is the same as the pitch of the unevenness 15 of the bonding surface of the substrate 5, but the depth of the groove is slightly shallower. In the example of the optical information medium shown in FIG. 4 as well, the method of bonding the substrates 1 and 5 is the same as the above-described example, and a detailed description thereof will be omitted.

FIG. 5 is a schematic sectional view showing a state in which the bonding surfaces of substrates 1 and 5 are adhered in still another example of the optical information medium according to the present invention. In the above-described example, the protective layer 14 made of an ultraviolet-curable resin is provided on the reflective layer 13 on the substrate 1 side. In contrast, in the example shown in FIG. Without the reflection layer 13 on the bonding surface
And the substrate 1 and the substrate 5 are bonded together via an adhesive. In this case, unevenness 16 may be provided on the bonding surface of the reflective layer 13 on the substrate 1 side, and the depth of the groove of the unevenness 16 is slightly smaller than that of the unevenness 15 on the bonding surface of the substrate 5. Also in the example of the optical information medium shown in FIG. 5, the method of bonding the substrates 1 and 5 is the same as in the above-described example, and a detailed description thereof will be omitted.

FIG. 6 shows still another example of the optical information medium according to the present invention, and is a schematic sectional view showing a state where the bonding surfaces of the substrates 1 and 5 are bonded. In the example shown in FIG. 6, a metal layer 17 made of a metal film of gold, aluminum, silver, copper, or the like or an alloy film thereof is formed on the bonding surface of the substrate 5. Is provided. The metal layer 17 has a thickness of about 20 to
50 μm, formed on the bonding surface of the substrate 5 by a method such as sputtering. The substrate 5 and the substrate 1 thus formed may be bonded to each other via an adhesive.

In the example of the optical information medium shown in FIG. 6, the method of bonding the substrates 1 and 5 is the same as in the above-described example, and a detailed description thereof will be omitted. In this way, even if the application of the adhesive becomes uneven due to the lowering of the viscosity, the adhesive is blocked by the above-mentioned metal layer 17, so that it does not appear visually on the surface and the disk appearance is good. Becomes

[0035]

Next, embodiments of the present invention will be described with specific numerical values. (Example 1) A polycarbonate substrate having an outer diameter of 120 mmφ, an inner diameter of 15 mmφ, a thickness of 0.597 mm, and a refractive index of 1.59, and a tracking pitch p =
A transparent first substrate 1 having a 0.74 μm tracking groove 3 was prepared. A solution of a cyanine dye (trimethine dye) was spin-coated on the surface of the light-transmitting substrate 1 having the groove 3 to form a recording layer 12.

Further, Au was sputtered on the recording layer 12 to form a reflective layer 13. On top of this, an ultraviolet curable resin (SD21 manufactured by Dainippon Ink and Chemicals, Inc.)
1) was spin-coated, and this was irradiated with ultraviolet rays to be cured, thereby forming a protective layer 14. Separately the same outer diameter 120 as above
A polycarbonate substrate 5 having a diameter of 15 mm, an inner diameter of 15 mm, and a thickness of 0.597 mm was prepared. On one side of this substrate 5,
The unevenness 15 having a groove having a pitch of 0.74 μm and a half width of 0.3 μm is formed.

Next, while rotating the first substrate 1 around the center of the center hole 4 at a low speed, an ultraviolet curable resin adjusted to have a viscosity of 150 cps around the center hole 4 on the side of the protective layer 14 of the substrate 1. A system adhesive was applied. next,
The bonded surface having the irregularities 15 of the second substrate 5 was placed on the substrate 1, and the substrates 1 and 5 were pressed from above. Subsequently, the superposed substrates 1 and 5 were rotated at a speed of 2500 rpm, the adhesive was spread on the outer peripheral side of the substrates 1 and 5 by centrifugal force, and excess adhesive was shaken off.

Next, the second substrate 5 is irradiated with an ultraviolet lamp.
The substrates 1 and 5 were fixed to each other by irradiating the adhesive between the substrates 1 and 5 with ultraviolet rays through the substrate and curing the adhesive. This produced an optical information medium. As a result of measuring the adhesive strength of the bonded substrates 1 and 5 using a tensile tester, it was found to be 150 kgf / cm ² . The substrates 1 and 5 were peeled off, and the film thickness of the adhesive layer 11 was measured between them.
35 μm, and the average was 30 μm. Furthermore, the porosity of the adhesive layer 11 was measured to be 0% by measuring the diameter of the bubble and measuring the occupied area ratio using a dimensional measuring device.

(Example 2) In Example 1, the ultraviolet curable resin-based adhesive adjusted to a viscosity of 100 cps was used, and the adhesive was spread between the substrates 1 and 5 by centrifugal force. The rotation speed of the substrates 1 and 5 is set to 1500 rpm
An optical information medium was manufactured in the same manner as in Example 1 except that

Using a tensile tester, the adhesive strength of the bonded substrates 1 and 5 was measured and found to be 200 kgf / cm.
^{Was 2} . The substrates 1 and 5 are peeled off, and the adhesive layer 11 between them is removed.
The film thickness was measured to be 25 to 35 μm, with an average of 3
It was 0 μm. Furthermore, by measuring the diameter of the bubble and measuring its occupied area ratio using a dimension measuring device,
As a result of measuring the porosity of this adhesive layer 11, it was 0%.

(Example 3) In Example 1, an ultraviolet curable resin-based adhesive adjusted to have a viscosity of 220 cps was used, and this adhesive was developed between the substrates 1 and 5 by centrifugal force. The rotation speed of the substrates 1 and 5 is 3500 rpm
An optical information medium was manufactured in the same manner as in Example 1 except that

Using a tensile tester, the adhesive strength of the bonded substrates 1 and 5 was measured and found to be 100 kgf / cm.
^{Was 2} . The substrates 1 and 5 are peeled off, and the adhesive layer 11 between them is removed.
The film thickness was measured to be 20 to 35 μm.
It was 8 μm. Furthermore, by measuring the diameter of the bubble and measuring its occupied area ratio using a dimension measuring device,
As a result of measuring the porosity of this adhesive layer 11, it was 0%.

Comparative Example 1 In Example 1, except that the substrate 5 having a flat bonding surface and no irregularities 15 was used, and that an ultraviolet curable resin-based adhesive adjusted to a viscosity of 500 cps was used. An optical information medium was manufactured in the same manner as in Example 1. As a result of measuring the adhesive strength of the bonded substrates 1 and 5 using a tensile tester, 10 kgf /
cm ² . The substrates 1 and 5 were peeled off, and the film thickness of the adhesive layer 11 between them was measured. The result was 15 to 25 μm, and the average was 20 μm. In addition, using a dimension measurement device,
The porosity of the adhesive layer 11 was determined to be 0% by measuring the diameter of the bubbles and determining the occupied area ratio thereof.

Comparative Example 2 An optical information medium was produced in the same manner as in Example 1 except that the substrate 5 having a flat bonding surface and no irregularities 15 was used. As a result of measuring the adhesive strength of the bonded substrates 1 and 5 using a tensile tester, the adhesive strength was 15 kgf / cm ² , which was 10% as compared with the example. The substrates 1 and 5 were peeled off, and the thickness of the adhesive layer 11 was measured between them.
The average was 8 μm. Furthermore, the porosity of the adhesive layer 11 was measured to be 0% by measuring the diameter of the bubble and measuring the occupied area ratio using a dimensional measuring device.

Comparative Example 3 An optical information medium was produced in the same manner as in Example 1 except that an ultraviolet curable resin-based adhesive adjusted to the same viscosity as that of Comparative Example 1 at 500 cps was used. made. Using a tensile tester,
As a result of measuring the adhesive strength of the bonded substrates 1 and 5, 1
It was ²⁰ kgf / cm ² . The substrates 1 and 5 were peeled off, and as a result of measuring the film thickness of the adhesive layer 11 therebetween, 40 to 60 μm
m, and the average was 50 μm. Furthermore, the porosity of the adhesive layer 11 was measured by measuring the diameter of the bubble using a dimensional measuring device to determine the occupied area ratio, and the result was 10%.

[0046]

As described above, according to the present invention, 2
In an optical information medium having a structure in which a plurality of substrates 1 and 5 are bonded, an adhesive having a relatively low viscosity is used to form an adhesive layer 1
A fine adhesive layer can be obtained by suppressing the entry of fine bubbles into the substrate 1, and a larger bonding strength between the substrates 1 and 5 can be ensured with a thin adhesive layer. Moreover, at the time of pit formation, deterioration of jitter due to the presence of bubbles can be suppressed, so that variations in pit shape can be eliminated and tracking errors or focus errors can be prevented. When the adhesive is spread between the substrates 1 and 5,
The use of an adhesive with a relatively low viscosity allows for a uniform and fast spreading of the adhesive. In addition, it is possible to obtain the adhesive layer 11 having a predetermined thickness and to secure the necessary bonding strength of the substrates 1 and 5.

[Brief description of the drawings]

FIG. 1 is an exploded half-sectional perspective view showing an example of an optical information medium according to the present invention in a state before two substrates are bonded together.

FIG. 2 is a perspective view, partially in vertical section, showing the optical information medium.

FIG. 3 is a longitudinally enlarged side view of a main part of the optical information medium.

FIG. 4 is a vertical sectional side view showing a main part of another example of the optical information medium according to the present invention.

FIG. 5 is a vertical sectional side view of a main part showing still another example of the optical information medium according to the present invention.

FIG. 6 is a vertical sectional side view of a main part showing still another example of the optical information medium according to the present invention.

FIG. 7 is a partial side view showing a manufacturing process of the optical information medium.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 1st board | substrate 5 2nd board | substrate 11 Adhesive layer 14 Protective layer of a 1st board | substrate 15 Unevenness formed on the bonding surface of the 2nd board 16 Unevenness formed on the bonding surface of the 1st board

Continued on the front page (72) Inventor Emiko Hamada 6-16-20 Ueno, Taito-ku, Tokyo F-term in Taiyo Denki Co., Ltd. 5D029 RA08 RA28 5D121 AA07 FF03 FF20

Claims (7)

[Claims] 1. An optical information medium comprising a first and second substrates (1) and (5) bonded together and a signal recorded on at least one of the substrates (1) or a region capable of recording a signal. A substrate (1) of at least one of a first substrate (1) and a second substrate (5) bonded to each other,
The irregularities (15) and (16) formed on the bonding surface of (5) and repeating concave and convex in the radial direction, and the irregularities (1)
(5) An optical information medium comprising: an adhesive layer (11) in which a first substrate (1) and a second substrate (5) are adhered to each other on a bonding surface having (16) and (16). 2. The optical information medium according to claim 1, wherein the irregularities (15) and (16) of the first and second substrates (1) and (5) are spiral. 3. A metal layer is formed on a bonding surface of the first and second substrates (1) and (5), on which the signal is recorded or the substrate (5) having no area capable of recording the signal is provided. The optical information medium according to claim 1, wherein the optical information medium is formed. 4. The thickness of the adhesive layer (11) is 10 to 50 μm.
The optical information medium according to any one of claims 1 to 3, wherein 5. An optical information medium having a region on which a signal is recorded or a signal can be recorded on at least one of the substrates (1) and (5), which is bonded to the first and second substrates (1) and (5). In the method for manufacturing, at least one substrate (1),
A step of preparing a first substrate (1) and a second substrate (5) having irregularities (15) and (16) on the bonding surface of (5) which repeat concave and convex in the radial direction; A step of applying an adhesive to at least one of the first and second substrates (1) and (2), and overlapping the first substrate (1) and the second substrate (5) with each other; A step of joining, a step of spreading an adhesive between the bonding surfaces of the first substrate (1) and the second substrate (5) on the bonding surfaces, and a step of curing the spread adhesive to form an adhesive layer ( 11) forming an optical information medium. 6. The step of spreading the adhesive between the first and second substrates (1) and (5) comprises rotating the superposed first and second substrates (1) and (5) at a high speed. 6. A step of spreading the adhesive by centrifugal force by performing the step.
3. The method for producing an optical information medium according to claim 1. 7. The viscosity of the uncured adhesive is 80 to 250 c.
7. The method for manufacturing an optical information medium according to claim 5, wherein the optical information medium is ps.