JPH10106033A - Sticking type optical disk - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inexpensive and high quality sticking type optical disk by using a second resin substrate having no information part and obtained from a punched resin sheet and providing ruggedness on a sticking surface. SOLUTION: A recording part 12 formed with pits is formed on one surface of a transparent substrate 11 of a first resin substrate 10. On the other hand, the second resin substrate 20 is provided with a rugged surface 21, and this rugged surface 21 is overlapped the first resin substrate 10 so as to oppose to the recording part 12 of the first resin substrate 10, and two sheets of resin substrates are stuck to each other by adhesive 30. The second resin substrate 20 is formed by punching the resin sheet, and isn't provided with the recording part, thus, a reflection film and a protection film also.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disk, and more particularly to a bonded optical disk.

[0002]

2. Description of the Related Art Two optical disks on which information is recorded are bonded to each other with their information portions facing each other, and two layers of information are read from one side, and information is recorded on a laminated optical disk. In order to prevent warpage of the first optical disk substrate, there is a type in which a second substrate is bonded to a first optical disk substrate. In the latter case, the second substrate generally has exactly the same structure as the first optical disk, but a substrate on which no information is recorded is used.

[0003]

Therefore, in the conventional configuration for simply preventing the warp of the optical disk substrate on which information is recorded, the manufacturing cost is unnecessarily increased. The present invention solves such conventional disadvantages, at a low manufacturing cost,
Moreover, it is an object of the present invention to provide a bonded optical disk having excellent quality.

[0004]

In order to achieve the above object, a bonded optical disc according to the present invention has a first resin substrate having an information portion on one side of which information is written, and an information portion. In a bonded optical disk in which a second resin substrate not bonded is bonded, the second resin substrate is a substrate obtained by punching a resin sheet, and the second resin substrate is bonded. The surface is provided with irregularities.

Here, the height of the irregularities is 0.005 to 0.005.
It is preferable that the distance be in the range of 0.05 mm.

[0006] The concave / convex concave portions are connected over the entire bonding surface, the concave / convex concave portions are radially connected from the center boss hole portion to the outer peripheral portion, or the concave / convex portions form a maze, and the concave portion is a center boss hole. It is preferable to connect from the part to the outer peripheral part.

Further, it is preferable that the second resin substrate is made of the same resin as the first resin substrate.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION A bonded optical disk according to the present invention is obtained by punching a first resin substrate having an information portion having information written on one surface thereof and a resin sheet,
The second resin substrate, which has irregularities on one surface thereof and does not have an information part, is connected to the information part side surface of the first resin substrate and the irregular surface of the second resin substrate. Are attached to each other.

FIG. 1 is a schematic sectional view of one embodiment of the present invention. Information is already recorded on the first resin substrate 10. That is, a recording portion 12 having pits is formed on one surface of the transparent substrate 11 of the first resin substrate 10, and the recording portion 12 is provided with a reflective film 13 made of, for example, aluminum. The top is covered with a UV-curable protective film layer 14.

On the other hand, the second resin substrate 20 has an uneven surface 21.
And the concave and convex surface 21 is superposed on the first resin substrate so as to face the recording portion 12 of the first resin substrate 10, and the two resin substrates are bonded with an adhesive 30. . Common center boss holes 10A and 20A are provided in the first and second resin substrates. The second resin substrate 20 is formed by stamping a resin sheet, and has no recording portion, and therefore has neither a reflective film nor a protective layer.

Since the second resin substrate is obtained by simply punching a resin sheet, this bonded optical disk can be manufactured at low cost.

The first and second resin substrates are preferably made of the same resin, for example, a polycarbonate resin or a polymethyl methacrylate resin. Second
Whether the thickness of the resin substrate is equal to the thickness of the first resin substrate,
Alternatively, it is preferably slightly thin. Usually, an adhesive is applied to the protective film layer formed on the first resin substrate by a roll coating method, a screen printing method, or the like, and then the second resin substrate is attached. The adhesive used is UV curable,
A thermosetting type, a thermoplastic type and the like are not particularly limited, but an ultraviolet curable type is preferably used because of easy handling.

In order to suppress the warpage of the bonded optical disk, the thickness of the adhesive is uniform over the entire bonded surface, and air bubbles of 0.5 m or more which adversely affect the mechanical characteristics are bonded to the bonded surface. It must be absent. In the bonded optical disk of the present invention, irregularities are formed on the bonding surface of the second resin substrate, and the concave portion is connected from the central portion of the disk to the outer peripheral portion so as to function as a groove through which bubbles flow. Therefore, excess adhesive and air bubbles are discharged from the outer peripheral portion of the substrate through the concave portions of the uneven surface. If the height of the unevenness is less than 0.005 mm, the groove is too shallow and the flow of air bubbles is poor, and if it exceeds 0.05 mm, the adhesiveness is poor.

With such a configuration of the present invention, the warpage of the optical disk substrate can be suppressed stably.

[0015]

【Example】

Example 1 As a first resin substrate, an outer diameter of 120 mm and an inner diameter of 15 m
m, thickness 0.6mm, radius of stamper holder groove 1
A polycarbonate substrate provided between 7 mm and 18 mm was used. A recording portion was formed on the signal side of the polycarbonate substrate, and an aluminum film having an average thickness of 60 nm was formed thereon as a light reflection layer by DC magnetron sputtering. Further, an ultraviolet curing agent SD-211 is further placed thereon.
(Dai Nippon Ink Chemical Co., Ltd.) was applied to a thickness of 4 μm by spin coating, and was cured by irradiating with an ultraviolet ray with an ultraviolet ray irradiator to form a protective layer. An acrylic UV-curable adhesive, MH-7543 manufactured by Mitsubishi Rayon Co., Ltd., having a thickness of 50 μm was applied on the protective layer by screen printing.
m. On the adhesive layer, a second resin substrate obtained by punching the polycarbonate resin sheet into the same shape as the first resin substrate was horizontally dropped with the uneven surface facing down and bonded.

Further, a load of 1 kg / cm ² was applied from the inner peripheral side to the outer peripheral side by a pressing method from the second resin substrate side. At this time, the bubbles entrained at the time of bonding were released through the concave portions provided in the second resin substrate. afterwards,
Ultraviolet rays were irradiated from the second resin substrate side to cure the adhesive.

FIG. 2 is a partial perspective view schematically showing the uneven surface of the second resin substrate. In this embodiment, the convex portions 22 are formed randomly and the concave portions 23 are formed so as to connect from the center boss hole to the outer periphery. Such an uneven surface can be obtained, for example, by casting a polycarbonate resin on the uneven surface, or by pressing or calendering a flat sheet.

After the adhesive was cured, the bonded optical disk shown in FIG. 1 was obtained. The warpage of the bonded optical disk was -4.0 mrad in R-Tilt value, and the warpage was small. Note that the R-Tilt value is calculated based on “Optical measurement and evaluation technology” (published by Japan Industrial Technology Center,
pp. 100 to 102).

Embodiment 2 As a second resin substrate, a convex portion 22 as shown in FIG.
Example 1 except that polycarbonate having an uneven surface radially extending from the central portion to the outer periphery with the concave portion 23 interposed therebetween was used.
In the same manner as in the above, a bonded optical disk was prepared. The warpage of this bonded optical disk is represented by an R-Tilt value of −
It was 5.0 mrad.

Example 3 A second resin substrate was made in the same manner as in Example 1 except that a polycarbonate having an uneven surface formed by maze-shaped convex portions 22 and concave portions 23 was used as shown in FIG. To produce a bonded optical disk. The warpage of the bonded optical disk was -3.5 mrad in R-Tilt value, and the warpage was small.

Comparative Example A bonded optical disk was prepared in the same manner as in Example 1 except that a flat polycarbonate having no uneven surface was used as the second resin substrate. The warpage of this bonded optical disk was -8.0 mrad in R-Tilt value, and the warpage was large, so that it was not practically used.

[0022]

As described above, according to the present invention,
As the second resin substrate, a substrate obtained by simply punching a resin sheet is used, and since the bonding surface of the second resin substrate has irregularities, a high-quality bonding can be performed at a low manufacturing cost. Type optical disc can be provided.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of an embodiment of the present invention.

FIG. 2 is a partial perspective view showing an example of an uneven surface of a second resin substrate.

FIG. 3 is a partial plan view showing another example of the uneven surface of the second resin substrate.

FIG. 4 is a partial plan view showing still another example of the uneven surface of the second resin substrate.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 1st resin substrate 10A Center boss hole 11 Transparent substrate 12 Recording part 13 Reflective film 20 2nd resin substrate 20A Center boss hole 21 Uneven surface 22 Convex portion 23 Concave portion

Claims (6)

[Claims] 1. A bonded optical disk in which a first resin substrate having an information portion having information written on one surface thereof and a second resin substrate having no information portion are bonded to each other. A bonded optical disc, characterized in that the resin substrate is a substrate obtained by punching a resin sheet, and the second resin substrate is provided with irregularities on a bonding surface. 2. The height of the unevenness is 0.005 to 0.05.
2. The bonded optical disk according to claim 1, wherein the distance is in the range of mm. 3. The bonded optical disk according to claim 1, wherein the concave portions of the unevenness are connected to each other over the entire bonding surface. 4. The bonded optical disk according to claim 1, wherein the concave portions of the concave and convex portions are radially connected from a center boss hole to an outer peripheral portion. 5. The bonded optical disk according to claim 1, wherein the unevenness has a maze shape, and the concave portion is connected from the center boss hole to the outer peripheral portion. 6. The method according to claim 1, wherein the second resin substrate is made of the same resin as the first resin substrate.
A bonded optical disk according to any one of the above.