JPH09167382A - Laminated disk and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laminated disk having an excellent mechanical characteristic as a disk, especially in surface wobbling acceleration by forming a protective film in the peripheral part of a disk unit plate before being laminated and making the height of the raised part of the peripheral part small. SOLUTION: A disk unit plate used for the laminated disk is formed in such a manner that after a recording layer 2 is formed, the peripheral part of a transparent substrate 1 is covered with a protective layer 3 made of a UV resin and the raised part 4 of the transparent substrate 1 is made flat even when the raised part 4 exists. When the height of the raised part of the protective layer in the peripheral part of the disk unit plate is (d), the value of (d) is set to 0.5 to 5μm. Thus, when two or such disk unit plates are laminated together, no bending or deformation occurs in the disk and a laminated disk whose mechanical characteristic of, especially in surface wobbling acceleration, is improved, can be provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bonded type optical information disk for recording, reproducing or erasing information by using light from a magneto-optical disk, a phase change disk, etc. Relates to an optical information disc having improved mechanical characteristics and a manufacturing method thereof.

[0002]

2. Description of the Related Art Disc-shaped recording media (hereinafter referred to as "discs") such as magneto-optical discs, phase-change discs, etc. for recording, reproducing or erasing information by light are used in order to increase the storage capacity. The method of using as a laminated disc formed by laminating disc single plates is generally practiced.

In general, such a disc is formed by molding a transparent thermoplastic resin such as polycarbonate, polymethylmethacrylate, and amorphous polyolefin into a disc shape by an injection molding method, and then forming a recording layer on one side of the disc. It is manufactured by laminating a protective layer made of UV resin on the above, and then laminating two obtained disk single plates so that the surfaces on which the recording layers are formed face each other with an adhesive.

[0004]

Generally, as shown in FIG. 2, a transparent resin substrate obtained by an injection molding method has a raised portion 4 having a height of about 2 to 20 microns on the peripheral portion. For this reason, even in the disk single plate obtained by using such a substrate, the swelling portion 5 of the protective layer due to the swelling of the substrate as shown in FIG. 3 is generated. When a bonded disc is manufactured using such a disc single plate, warp or distortion occurs in the disc after bonding,
There is a problem that the mechanical characteristics of the disk, especially the surface wobbling acceleration, are deteriorated.

In particular, recently, for the purpose of thinning and increasing the density of a disc, 0.6 m, which is half of the conventional 1.2 mm thickness, is used.
The manufacture of a thin bonded disk using an m-thick substrate has been studied, but since the rigidity of the disk becomes lower, the warp and distortion of the bonded disk due to the swelling of the peripheral portion are more remarkable. It has been clarified by the study of the present inventor that this occurs.

Further, in order to improve the recording / reproducing speed of the disc, the rotating speed of the disc at the time of recording / reproducing tends to increase from 1800 rpm to 3600 rpm, and therefore the demand for the mechanical characteristics of the disc is further increased. It is rising. Under such circumstances, the solution of the above problems has been strongly desired.

[0007]

In order to solve the above problems, the present inventor has diligently studied.

As a result, in the step of laminating the protective layer made of UV resin on the transparent substrate on which the recording layer is formed, U
After applying the V resin on the transparent substrate, UV light is irradiated through a photomask that shields the peripheral edge of the substrate to cure the UV resin other than the peripheral edge so that the peripheral edge does not harden, and then the transparent By rotating the substrate at high speed, the uncured UV resin in the peripheral portion is shaken off until the swelling due to the resin disappears, and then the peripheral portion or the entire surface of the transparent substrate is irradiated with UV light to cure the UV resin in the peripheral portion. By doing so, it is possible to form a flat protective layer having a small height of swelling in the peripheral portion, and using a disc single plate having a small height of swelling of the protective layer in the peripheral portion thus obtained. When a bonded disc is manufactured by using the bonded disc, there is no warp or distortion in the bonded disc, and the bonded disc has excellent mechanical properties, especially surface runout acceleration. Found that it is possible to obtain a click, they have accomplished the present invention.

That is, in the bonded disc of the present invention, two disc single plates each having a recording layer and a protective layer made of UV resin sequentially laminated on a transparent substrate are arranged such that the surfaces having the recording layers face each other. In a bonded disc formed by laminating as described above, when the height of the swelling of the protective layer at the peripheral edge portion of the disc single plate before laminating is d, the value of d of the disc single plate to be laminated is 0.5. ~ 5μ
m.

The bonded disk of the present invention and the method for manufacturing the same will be described below in detail.

The bonded disk of the present invention is characterized by being manufactured using a disk single plate as shown below. FIG. 1 shows a sectional structure of a peripheral edge portion of a disk single plate used in the bonded disk of the present invention. The disk single plate used for the bonded disk of the present invention is UV
The protective layer 3 made of resin covers the peripheral portion of the transparent substrate 1 and is formed so as to flatten the raised portion 4 even when the transparent substrate has the raised portion 4. At this time, the height of the raised portion 6 of the protective layer at the peripheral portion is d
Then, the value of d is 5 μm or less. For this reason, when two such disc single plates are bonded together, warping or distortion of the disks does not occur, and it is possible to obtain a bonded disk that is excellent in mechanical characteristics, especially in surface wobbling acceleration.

Next, a method of manufacturing the bonded disk of the present invention will be described.

First, as the first step, the recording layer 2 is formed on the transparent substrate. The recording layer formed here is a recording film capable of recording, reproducing and erasing information using light such as magneto-optical recording and phase change recording.

Next, as a second step, UV resin is applied on the recording layer of the transparent substrate on which the recording layer is formed by spin coating. As the UV resin used here, those generally used as a protective layer for an optical disk can be used. The thickness of the protective layer formed at this time is h> t, where h is the average thickness of the protective layer and t is the height of the raised portion 4 at the peripheral edge of the transparent substrate, as shown in FIG. Is set. If h is less than or equal to t, then
The protective layer cannot sufficiently cover the raised portion 4 at the peripheral portion of the transparent substrate, and the raised portion of the protective layer cannot be suppressed to 5 μm or less.

Next, as a third step, as shown in FIG. 5, the transparent substrate coated with the UV resin is irradiated with UV light, and U is irradiated.
V resin is cured. At this time, the UV resin coating film other than the peripheral portion is selectively cured while preventing the coating film on the peripheral portion from being cured through the photomask 8 which shields the peripheral portion of the substrate. The length of the peripheral edge portion a that is shielded using a photomask is 0.5 mm to 2 m from the outer peripheral edge of the transparent substrate.
m. This is because when the light-shielding range is too narrow, the swelling of the protective layer remains unreduced to 5 μm or less, and when it is too wide, the protective layer at the peripheral edge becomes thin in a wide range, so that the protective film is protected. This is to prevent the possibility of performance problems. Further, the distance b between the mask and the surface of the UV resin coating film is set to 0 <b ≦ 2 mm in order to prevent UV light from flowing into a portion shielded by the mask and curing the UV resin in that portion. preferable.

Next, as a fourth step, as shown in FIG. 6, the transparent substrate having the uncured UV resin coating film portion 7 on the peripheral portion is rotated at a high speed to remove the uncured UV resin on the peripheral portion by the resin. Shake until the climax of is disappeared. Optimum rotation speed and rotation time at this time depend on the UV used.
Although it is determined by the viscosity of the resin, if the rotation speed is too low or the rotation time is too short, the swelling cannot be reduced to 5 μm or less, which is not preferable. Generally, it is preferable that the rotation speed is 2000 rpm or more and the rotation time is 5 seconds or more.

Next, in a fifth step, UV light is irradiated to the peripheral edge or the entire surface of the transparent substrate after the uncured UV resin in the peripheral edge has been shaken off, and the uncured UV in the peripheral edge is radiated.
Cure the resin. In this way, it is possible to obtain a disk single plate having a protective layer with a small bulge height at the peripheral edge.

Further, two disk single plates each having a protective layer having a small height of swell obtained in the sixth step are bonded together with an adhesive. As the adhesive, a hot melt adhesive, a UV curable adhesive, an anaerobic curable adhesive, a moisture curable adhesive, etc. can be used.
A hot melt adhesive is particularly preferably used. In this case, it is possible to apply the hot-melt pressure-sensitive adhesive to each of the bonded surfaces of both of the disk single plates by using a roll coater, and to bond the adhesive-coated surfaces to each other and then press from both surfaces. .

[0019]

EXAMPLES The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples.

Example 1 Diameter 130 mmφ, thickness 1.
A 2 mm polycarbonate magneto-optical disk substrate was molded using an injection molding machine. When the shape of the peripheral portion of this substrate was measured using a stylus type step measuring device, the height d of the raised portion was 14.7 μm at the maximum. After forming a magneto-optical recording layer on this magneto-optical disk substrate, a protective coating agent SD-301 manufactured by Dainippon Ink and Chemicals Co., Ltd. was applied to a thickness of 18 μm using a spin coater. Ushio Electric Co., Ltd. U was applied to the obtained UV resin coated substrate.
Ultraviolet rays were irradiated at a dose of 1000 mJ / cm ² using V cure to cure the UV resin coating film. At this time, a peripheral edge portion having a width of 1.5 mm from the outer peripheral edge of the substrate is shielded from light by using a quartz glass photomask on which chromium is vapor-deposited,
The periphery was prevented from hardening. At this time, the mask and the coating film surface were set so that the distance between them was 0.5 mm. Subsequently, this substrate was spin-coated at 6000 rpm.
It was rotated for 15 seconds, and the uncured UV resin on the peripheral edge was shaken off. After that, by using a spot cure manufactured by USHIO INC. To irradiate the peripheral edge of the rotating disk with UV light, ultraviolet rays are evenly distributed only near the peripheral edge of the disk at an irradiation amount of 1000 mJ / cm ^2. Irradiation was performed to cure the uncured UV resin on the peripheral portion. When the shape of the peripheral portion of the obtained magneto-optical disk single plate was measured by using an erosion type step measuring device, the value of the height d of the protrusion was 2 μm or less at any position on the outer circumference. In the same manner, ten magneto-optical disk single plates without bulges of 2 μm or more were manufactured on the peripheral portion. Two of the 10 sheets obtained were selected, and 2 pieces of hot-melt adhesive Melton 3S49 manufactured by Diabond Co., Ltd. were used with a roll coater.
Each of them was applied to a thickness of 2 μm and bonded by a press machine.
Similarly, the remaining eight magneto-optical disk single plates were also bonded in the same manner, and a total of five bonded disks were manufactured.

The surface runout acceleration of the five bonded disks obtained was measured by Ono Sokki Co., Ltd. mechanical property measuring device LM-10.
0 was measured under the rotation condition of 1800 rpm. 10
Table 1 shows the average values of the surface measurement results.

[0022]

[Table 1]

(Embodiment 2) Diameter 120 mmφ, thickness 0.
A 6 mm polycarbonate phase change disk substrate was molded using an injection molding machine. When the shape of the peripheral portion of this substrate was measured using a stylus type step difference measuring device, the height d of the raised portion was 7.3 μm at maximum. After forming a phase-change recording layer on this phase-change disk substrate, a protective coating agent SD-17 manufactured by Dainippon Ink and Chemicals, Inc. was applied on the recording layer with a spin coater so as to have a thickness of 10 μm. Ushio Electric Co., Ltd. was applied to the obtained coated substrate.
The UV resin coating film was cured by irradiating it with ultraviolet rays at an irradiation dose of 1000 mJ / cm ² using a UV curing product. At this time, a peripheral edge portion having a width of 1 mm from the outer peripheral edge of the substrate was shielded from light using a quartz glass photomask on which chromium was vapor-deposited, so that the peripheral edge portion was not cured. At this time, the mask and the coating film surface were set so that the distance between them was 0.5 mm. Then, this substrate was spin-coated at 4000 rpm for 20 minutes.
It was rotated for 2 seconds and the uncured UV resin on the peripheral portion was shaken off. Then, using a spot cure manufactured by Ushio Inc., the peripheral edge of the rotating disk is irradiated with UV light, so that the ultraviolet light is irradiated only near the peripheral edge of the disk.
Irradiation was performed uniformly at a dose of 00 mJ / cm ² to cure the UV resin in the uncured peripheral portion. The shape of the peripheral portion of the obtained single phase-change disk was measured using a stylus-type step difference measuring device. As a result, the height d of the protrusion was 1 μm or less at any position on the outer circumference. Similarly,
Ten phase-change disk veneers having no bulge of 1 μm or more were manufactured at the peripheral edge. Of the 10 sheets obtained, any 2 sheets were selected, and hot-melt adhesive Melton 3S49 manufactured by Diabond Co., Ltd. was applied to a thickness of 22 μm using a roll coater manufactured by Matsushita Industry Co., Ltd., and pressed. Pasted together with a container. Similarly, the remaining 8 phase-change disk single plates were also bonded in the same manner, and a total of 5 bonded disks were manufactured.

The surface runout acceleration of the five bonded disks obtained was measured by Ono Sokki Co., Ltd. mechanical property measuring device LM-21.
00 was used and the measurement was performed under the rotation condition of 3000 rpm. 1
Table 1 shows the average values of the measurement results on the 0th surface.

(Comparative Example 1) A transparent substrate for a magneto-optical disk similar to that used in Example 1 was used to form a magneto-optical recording layer in the same manner as in Example 1, followed by protection from Dainippon Ink Co., Ltd. The coating agent SD-301 was applied. The obtained UV resin-coated substrate was irradiated with ultraviolet rays at a dose of 1000 mJ / cm ² using UV cure manufactured by Ushio Inc. to cure the entire surface of the UV resin coating film.

The shape of the peripheral portion of the obtained magneto-optical disk single plate was measured using a stylus type step measuring device, and the height d of the raised portion was 13.5 μm at the maximum. Thereafter, in the same manner as in Example 1, the magneto-optical disk single plate 10
Five discs were produced by laminating and laminating.

The surface wobbling acceleration of the obtained five bonded disks was measured in the same manner as in Example 1. Table 1 shows the average values of the measurement results of 10 surfaces.

(Comparative Example 2) A transparent substrate for a phase change disk similar to that used in Example 2 was used to form a phase change recording layer in the same manner as in Example 2 and then protected by Dainippon Ink Co., Ltd. The coating agent SD-17 was applied. The obtained UV resin-coated substrate was irradiated with ultraviolet rays at a dose of 1000 mJ / cm ² using UV cure manufactured by Ushio Inc. to cure the entire surface of the UV resin coating film. When the shape of the peripheral portion of the obtained single phase-change disk was measured using a stylus type step measuring device, the height d of the raised portion was 6.7 μm at the maximum. Thereafter, in the same manner as in Example 2, ten phase change disk single plates were manufactured, and five bonded disks were manufactured by bonding.

The surface wobbling acceleration of the obtained five bonded disks was measured in the same manner as in Example 2. Table 1 shows the average values of the measurement results of 10 surfaces.

[0030]

According to the present invention, as described above, a protective film is formed on the peripheral edge of a single disc before bonding so that the peripheral edge is not raised as much as possible, and the obtained peripheral edge has a small raised height. By manufacturing a bonded disk using a single plate, it is possible to obtain a bonded disk that is excellent in the mechanical characteristics of the disk, especially in the surface wobbling acceleration.

[Brief description of the drawings]

FIG. 1 is a sectional view of a peripheral edge portion of a disk single plate used for a bonded disk of the present invention.

FIG. 2 is a cross-sectional view of a peripheral portion of a general substrate obtained by injection molding.

FIG. 3 is a sectional view of a peripheral edge portion of a disk single plate used for a conventional bonded disk.

FIG. 4 is a diagram showing a film thickness of a protective film to be applied in a manufacturing process of the bonded disk of the present invention.

FIG. 5 is a conceptual diagram when performing exposure while shielding the peripheral portion of the substrate with a mask in the process of manufacturing the bonded disc of the present invention.

FIG. 6 is a cross-sectional view of the peripheral portion of the substrate in which the protective film on the peripheral portion is in an uncured state in the process of manufacturing the bonded disk of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Transparent substrate 2 Recording layer 3 Protective layer 4 Rising part of transparent substrate 5 Rising part of conventional protective layer 6 Rising part of protective layer to which the present invention is applied 7 Uncured UV resin coating film 8 Photomask 9 After curing UV resin coating

Claims (2)

[Claims] 1. A stick formed by sticking two disc single plates each having a recording layer and a UV resin protective layer sequentially laminated on a transparent substrate so that the surfaces on which the recording layers are formed face each other. In the laminated disc, the height of the swelling of the protective layer at the peripheral portion of the disc single plate before adhering is d
, The value of d of the single disk of the laminated disk is 0.
A laminated disk having a thickness of 5 to 5 μm. 2. A step of forming a recording layer on a transparent substrate,
A step of applying a UV resin by a spin coating method to form a UV resin coating film on the recording layer of the transparent substrate having the recording layer formed thereon, and a step of forming the UV resin coating film on the transparent substrate having the recording layer formed thereon. UV through a photomask that shields the peripheral edge of the substrate
A step of irradiating light to selectively cure only the UV resin coating film other than the peripheral portion, and rotating the transparent substrate having the UV resin coating film whose peripheral portion is uncured at high speed to shake the uncured UV resin. The step of flying, the step of irradiating the peripheral portion or the entire surface of the transparent substrate after the UV resin in the peripheral portion is shaken off with UV light to cure the uncured UV resin in the peripheral portion, and the obtained disk veneer 2 A method for manufacturing a bonded disk, comprising a step of bonding the sheets using an adhesive.