JP2004178756A - Method of manufacturing multilayer optical disk, and optical disk - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To efficiently manufacture a multilayer optical disk which has high quality in mechanical characteristic and recording and reproducing signal characteristic by preventing the deformation of a first disk substrate caused by deposition stress and heat in the case of deposition of a recording film and heat in the case of initialization. <P>SOLUTION: After sticking a rigidifying plate 35 to a surface on a side opposite to the transfer layer 21 of a flexible sheet 20, a recording layer 37 is deposited on the transfer layer. After forming a protective layer 38 on the surface of the recording layer 37, the recording layer 37 is initialized. By preventing the deformation caused by deposition stress applied to the flexible sheet 20 in the case of deposition of the recording layer 37, the first disk substrate 40 is produced. A multilayer optical disk 46 is manufactured using the first disk substrate 40 and a second disk substrate 44. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for manufacturing a multilayer optical disk and an optical disk.
[0002]
[Prior art]
[Patent Document 1] Japanese Patent Application Laid-Open No. 2001-184471 [Patent Document 2] Japanese Patent No. 2942430 [Patent Document 3] Japanese Patent Application Laid-Open No. 5-174432 [Patent Document 4] Japanese Patent Application Laid-Open No. 9-293276 [Patent Document 5] In recent years, research on an optical information recording method has been advanced in the field of information recording. This optical information recording system is capable of non-contact recording and reproduction, achieves a recording density that is at least an order of magnitude higher than the magnetic recording system, and has a memory format of a read-only type, a write-once type, and a rewritable type. A wide range of applications from industrial to consumer use is considered as a method that has a number of advantages such as being able to cope with large-capacity files and realizing inexpensive large-capacity files. In particular, high-density information recording media such as digital audio disks and digital versatile disks, which are optical disks compatible with a read-only type memory format, and optical video disks have become widespread.
[0003]
In this type of optical disk, a reflective film made of a metal thin film such as an aluminum film is formed on an optical disk substrate which is a transparent substrate on which a concavo-convex pattern such as pits or grooves indicating information signals is formed. In order to protect from moisture and oxygen, a protective film is formed on the surface of the reflective film. When reproducing the information of such an optical disk, for example, the concave / convex pattern is irradiated with reproduction light such as laser light from the optical disk substrate side, and the information is detected by the difference between the reflectance of the incident light and the return light. .
[0004]
When manufacturing this optical disk, first, an optical disk substrate having a concavo-convex pattern is formed by injection molding or the like, a reflective film made of a thin metal film is formed on the surface of the optical disk substrate by vapor deposition or the like, and ultraviolet light is applied to the surface of the reflective film. A protective film is formed by applying a curable resin or the like.
[0005]
In order to cope with such a demand for a large recording capacity of such an optical disk, for example, as shown in Patent Document 1, a concave / convex pattern is formed on one surface of an optical disk substrate, and a halfway pattern is formed thereon. An optical disc having a total of two information substrate layers is disclosed in which a transparent film is formed, an uneven pattern is formed on the translucent film at intervals of several tens of μm, and a reflective film is formed thereon. Have been. As a function of the semi-transparent film of the optical disk having the two information substrate layers, it is essential that recording and reproduction can be performed on each of the first disk substrate side and the second disk substrate side. That is, if the transmissivity of the translucent film is too high, light absorption does not occur on the first disk substrate side, and recording and reproduction cannot be performed at all. Conversely, if the transmissivity of the translucent film is too low, no light reaches the second disk substrate side, and recording / reproducing cannot be performed on the second disk substrate side. Further, since it is necessary to set the lens numerical aperture NA of the pickup of the recording / reproducing apparatus to about 0.85, the signal surface on the laser incident side must be set to a position about 0.1 mm from the optical disk substrate surface.
[0006]
In order to manufacture the first disk substrate, for example, as shown in Patent Document 2, a flexible sheet such as a polyethylene terephthalate (PET) film is transported by a roll-to-roll method while a thermoplastic resin is applied to the sheet surface. Alternatively, a thermosetting resin is applied to transfer the fine concavo-convex pattern of the stamper and thermally cured, followed by a heat press method of forming a recording film, or a fine pattern of the stamper by applying an ultraviolet curable resin to the surface of a flexible sheet. There is a 2P (Photo Polymerization) method in which a recording film is formed after transferring the recording medium and curing the ultraviolet ray.
[0007]
[Problems to be solved by the invention]
When processing the inner and outer diameters of the flexible sheet on which this fine pattern has been transferred using a special punching machine, it is necessary to suppress the eccentricity of the inner diameter and the pre-groove to 60 μm or less. The work of removing and punching is performed for each flexible sheet. For this reason, the lead time is lengthened and quality variation is apt to occur.
[0008]
In Patent Document 3, eccentricity is removed by pressing rods from four directions against glass to which 2P resin is transferred to a stamper. However, the lead time is long, and it is applied only to a rigid body such as glass. Can not.
[0009]
Further, when a semi-transparent film is formed, the flexible sheet is easily deformed by the film forming stress, but it is difficult to form the film so that the flexible sheet finished in the final disk shape is hardly deformed.
[0010]
Further, the first disk substrate is deformed by the stress and the heat at the time of forming the translucent film, and it becomes impossible to uniformly initialize the translucent film which is the phase change film. In order to prevent the deformation of the disk substrate, as shown in Patent Document 4, the disk substrate is vacuum-held by a suction pad provided with a porous body. However, this method has a disadvantage that the vacuum pumping equipment and the disk substrate holder need to be connected to an exhaust pipe to evacuate the suction portion while the disk substrate is being held, which makes the configuration of the apparatus considerably complicated. is there. In addition, the disk substrate holder cannot be transported during the sputter deposition process, and is less versatile as a disk substrate transport means in the production of optical information recording media.
[0011]
Further, as shown in Patent Document 5, as a method for handling a flexible sheet, a reinforcing material is fixed to the flexible sheet by pressing and pressing, but the flexible sheet and the reinforcing material are strongly pressed so as to form a vacuum state. Therefore, there is a disadvantage that the sheet surface is easily damaged or scratches are easily generated.
[0012]
The present invention prevents such disadvantages, prevents deformation of the first disk substrate due to film formation stress and heat during recording film formation and heat during initialization, and provides high quality mechanical and recording / reproducing signal characteristics. It is an object of the present invention to provide a method of manufacturing a multilayer optical disk capable of efficiently manufacturing a multilayer optical disk and an optical disk manufactured by the method.
[0013]
[Means for Solving the Problems]
The method for manufacturing a multilayer optical disc according to the present invention is characterized in that the rigidity is large on the surface opposite to the transfer surface of the transfer layer on which the pattern of the first stamper provided on one surface of the flexible sheet is transferred. After attaching the application substrate, a recording layer is formed on the transfer surface, a protective layer is formed on the surface of the recording layer, the recording layer is initialized, and after the recording layer is initialized, the rigidity application substrate is removed from the flexible sheet. The first disk substrate is peeled off, and the flexible sheet is prevented from being deformed due to the stress at the time of forming the recording layer and the heat at the time of initialization, and uniform initialization is performed.
[0014]
Further, after forming a pattern of the second stamper on the substrate by injection molding, a recording layer is formed on the surface of the substrate, a protective layer is formed on the surface of the recording layer, and the recording layer is initialized to form a second disk substrate. It is fabricated and bonded to the protective layer of the first disk substrate and the protective layer of the second disk substrate to produce a multilayer optical disk having stabilized recording / reproducing signal characteristics and mechanical characteristics.
[0015]
In addition, the flexible sheet has a peelable protective sheet on a surface opposite to the transfer layer, a rigidity-imparting substrate is attached to the protective sheet, a recording layer is formed and initialized, and then protected from the flexible sheet. It facilitates peeling of the sheet and the rigidity-imparting substrate.
[0016]
Further, the flexible sheet is made of a continuous raw material, and it is desirable that the pattern of the stamper be continuously transferred to form a transfer surface and then processed into a disk shape.
[0017]
Furthermore, when forming the transfer surface on the flexible sheet, an ultraviolet curable resin is applied on the stamper, and a spin-rotating is performed to form an ultraviolet curable resin layer having a predetermined thickness, and the flexible sheet is pressed against the formed ultraviolet curable resin layer. It is preferable to form the transfer surface by irradiating ultraviolet rays while irradiating. By using a monomer raw material having no molecular weight distribution as the ultraviolet curable resin, the variation in the circumferential thickness of the transfer layer is reduced. It is desirable that the flexible sheet and the protective sheet have the same light transmittance.
[0018]
An optical disk according to the present invention is manufactured by the method for manufacturing a multilayer optical disk.
[0019]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 is a block diagram showing the configuration of a multi-layer optical disc manufacturing apparatus according to the present invention. As shown in the figure, a multi-layer optical disc manufacturing apparatus 1 includes a first manufacturing apparatus 2, a second manufacturing apparatus 3, and a bonding apparatus 4. The first manufacturing device 2 is for manufacturing a first disk substrate of an optical disk having a two-layer recording film, and includes a transfer device 5, an outer diameter processing device 6, a rigidity imparting device 7, a film forming device 8, a protective layer It has a forming device 9, an initialization device 10, and a peeling device 11. The transfer device 5 forms a transfer layer on a flexible sheet. The outer diameter processing device 6 processes the flexible sheet on which the transfer layer is formed into a disk having a predetermined outer diameter. The rigidity imparting device 7 imparts rigidity to the flexible sheet by attaching a substrate having rigidity to the surface of the flexible sheet processed into a disk opposite to the transfer layer. The film forming apparatus 8 forms a recording layer on a transfer layer of a rigid sheet provided with rigidity. The protective layer forming device 9 forms a protective layer on the recording film. The initialization device 10 initializes the formed recording layer. The peeling device 11 peels a rigid substrate from the flexible sheet to form a first disk substrate.
[0020]
A manufacturing method for manufacturing a first disk substrate with the first manufacturing apparatus 2 will be described in the order of steps. First, as shown in the perspective view of FIG. 3, a protective sheet 21 that can be peeled off on one side of a flexible sheet 20 of a synthetic resin having a constant thickness, a tough and high impact strength, for example, a 75 μm thick polycarbonate. The formed roll-shaped raw material 22 is prepared. This web 22 can be wound up using two rolls. Then, the width in the direction perpendicular to the winding direction of the web 22 is set to 180 mm, and a center hole 23 of 15 mm is formed at a constant pitch, for example, 180 mm pitch in the center of the web 22 in the width direction.
[0021]
As shown in the configuration diagram of FIG. 3, the transfer device 5 has a drive roll 24 and a driven roll 25 that can move in the vertical direction while holding and winding the web 22, a center hole of 15 mm in advance, and a preformat. It has a center pole 27 that rotates while holding a stamper 26 on which a pattern is formed, pressing means 28 that presses the web 22 against the stamper 26, and an ultraviolet irradiation device 29. The web 22 is set on the driving roll 24 and the driven roll 25 of the transfer device 5, and the center hole 23 of the web 22 is positioned with respect to the center pole 27. In this state, as shown in FIG. 3A, the stamper 26 is set on the center pole 27, the ultraviolet curable resin 30 is applied on the surface of the stamper 26, and the center pole 27 is rotated by spinning, so that the ultraviolet curable resin 30 is removed. An ultraviolet curable resin film is formed by shaking off to a predetermined film thickness. After that, the drive roll 24 and the driven roll 25 holding the web 22 are lowered toward the stamper 26 to bring the flexible sheet 20 of the web 22 into contact with the ultraviolet curable resin film. Then, as shown in FIG. 3 (b), the raw material 22 is pressed by a bar-shaped pressing portion 28a made of, for example, a synthetic resin or a metal of the pressing means 28 at a position 90 mm before and after in the winding direction from the position of the center pole 27. Is pressed to the stamper 27 side with a constant pressure to apply ultraviolet light from an ultraviolet irradiation device 29 in a state where tension is applied to the raw material 22 to form the transfer layer 31. In order to form the transfer layer 31 with an appropriate film thickness, it is desirable to use a monomer having a viscosity of 10 to 300 mPa · s and having no molecular weight distribution for the ultraviolet curable resin 30. FIG. 4 shows the variation in the film thickness in the circumferential direction of the transfer layer 31 when a monomer having no molecular weight distribution and a monomer having a large molecular weight distribution are used. As shown in FIG. 4, when a monomer having no molecular weight distribution is used, the thickness of the transfer layer 31 in the circumferential direction hardly varies, and the transfer layer 31 can be formed with a uniform thickness. After the transfer layer 31 is formed, the pressing by the pressing means 28 is released, the driving roll 24 and the driven roll 25 are raised, the raw material 22 is separated from the center pole 27, and the raw material 22 is wound by the pitch of the center hole 23, for example, by 180 mm. . Then, the process of forming the transfer layer 31 is sequentially repeated. After the transfer layer 31 is formed for each central hole 23 of the flexible sheet 20 of the material 22, the material 22 on which the transfer layer 31 is formed is removed from the driving roll 24 and the driven roll 25 and sent to the outer diameter processing device 6.
[0022]
The outer diameter processing device 6 processes the sent raw material 22 into a disk shape having a diameter of 180 mm centering on each center hole 23, and continuously manufactures a flexible substrate 32 shown in FIG. The manufactured flexible substrates 32 are sequentially sent to the stiffness imparting device 7. As shown in FIG. 6A, the stiffness imparting device 7 has a center pole 33 of the same size as that of the transfer device 5, and is made of a PC substrate, a glass substrate, or a metal substrate on which an adhesive sheet 34 is formed on one surface. The rigidity-imparting substrate 35 having rigidity and large heat capacity is set on the center pole 33 with the adhesive sheet 34 facing upward. Then, the flexible substrate 32 is set so that the protection sheet 21 of the flexible substrate 32 adheres to the adhesive sheet 34, and another protective layer is formed on the transfer layer 31 of the flexible substrate 32 as shown in FIG. The flexible substrate 32 is pressed from above the protective sheet 36 with an elastic body, and the protective sheet 21 of the flexible substrate 32 is bonded to the adhesive sheet 34 of the rigidity-imparting substrate 35. When the flexible substrate 31 is bonded to the rigidity-imparting substrate 35, the protective sheet 36 is applied to the surface of the transfer layer 31 to press the flexible substrate 32, thereby preventing the transfer layer 31 from being damaged and smoothing the transfer surface. Can be kept.
[0023]
After bonding the rigidity-imparting substrate 35 to the flexible substrate 32, the protective sheet 36 on the surface of the transfer layer 31 is removed and sent to the film forming apparatus 8. The film forming apparatus 8 forms the recording layer 37 on the surface of the transfer layer 31 of the flexible substrate 32 as shown in FIG. When the recording layer 37 is formed, the rigidity imparting substrate 35 is attached to the flexible substrate 32. Therefore, it is possible to prevent the flexible substrate 32 from being deformed by the film forming stress applied to the flexible substrate 20 during the film formation. it can.
[0024]
After the recording layer 37 is formed on the transfer layer 31, the recording layer 37 is sent to the protective layer forming apparatus 9, and a protective layer 38 is formed on the surface of the recording layer 37 as shown in FIG. Thereafter, the recording layer 37 is sent to the initialization device 10, and is initialized by applying heat to the recording layer 37, as shown in FIG. When the recording layer 37 is initialized, a rigidity-imparting substrate 35 having a large heat capacity is bonded to the flexible substrate 32. Since the thermal deformation of the substrate 32 is suppressed by the rigidity-imparting substrate 35, the flexible substrate 32 can be prevented from being deformed by heat at the time of initialization, uniform initialization can be achieved, and the reflectance does not fluctuate. Good mechanical properties can be obtained. FIG. 9 shows a temperature change characteristic of the transfer surface of the transfer layer 31 with respect to the thickness of the rigidity imparting substrate 35 at the time of the initialization. As shown in FIG. 9, when the thickness of the rigidity imparting substrate 35 is about 1 mm, the temperature of the transfer surface can be significantly reduced.
[0025]
After the recording layer 37 is initialized, the flexible substrate 32 having the recording layer 37 and the rigidity-imparting substrate 35 is sent to the peeling device 11, where the flexible substrate 32 at the boundary between the flexible sheet 20 and the protective sheet 21 of the flexible substrate 32 is moved. After peeling, as shown in FIG. 8C, a first disk substrate 40 having the flexible sheet 20, the transfer layer 31, the recording layer 37, and the protective layer 38 is manufactured. FIG. 10 shows the result of measuring the warpage of the first disk substrate 39 manufactured by peeling the stiffening substrate 35 and the like while changing the thickness of the stiffening substrate 35. As shown in FIG. 10, when the recording layer 37 is initialized, the rigidity imparting substrate 35 suppresses the thermal deformation of the flexible substrate 32, and the first disk substrate 40 without warpage can be manufactured.
[0026]
Next, when a second disk substrate is manufactured by the second manufacturing device 3, as shown in FIG. 11, the signal surface of the second stamper is formed on the substrate 41 by injection molding by the molding device 12, and then the film is formed. The recording layer 42 is formed on the surface of the substrate 41 by the device 13, and the protective layer 43 is formed on the surface of the recording layer 42 by the protective layer forming device 14. After that, the recording layer 42 is initialized by the initialization device 15, and the second disk substrate 44 is manufactured.
[0027]
The first disk substrate 40 manufactured by the first manufacturing apparatus 2 and the second disk substrate 44 manufactured by the second manufacturing apparatus 3 are sent to the bonding apparatus 4 and, as shown in FIG. The protective layer 38 of the disk substrate 40 and the protective layer 43 of the second disk substrate 44 are bonded with a pressure-sensitive adhesive or an ultraviolet curable resin 45, and as shown in FIG. 12, the first recording layer 37 and the second A multilayer optical disk 46 having the recording layer 42 is manufactured. When the multilayer optical disk 46 is manufactured, the ultraviolet curable resin 45 for bonding the first disk substrate 40 and the second disk substrate 44 has a proper thickness by using a material having a viscosity of 100 to 1000 mPa · s. Can be obtained. The multilayer optical disk 46 manufactured in this manner has no change in reflectivity and good mechanical characteristics. As a result of recording on the multilayer optical disk 46 and confirming a reproduced signal, stable high-quality signal characteristics with a clear eye pattern are obtained. I was able to get.
[0028]
In the above description, the case where the recording layer 37 is formed after the rigidity providing substrate 35 is attached to the flexible substrate 32 has been described. However, the tension is applied to the flexible substrate 32 so that the surface of the transfer layer 31 is stretched. After the recording layer 37 is formed, the recording layer 37 may be initialized by attaching a rigidity-imparting substrate 35 having a large heat capacity to the flexible substrate 32. For example, as shown in FIG. 13A, the raw substrate 22 on which the transfer layer 31 is formed is processed with an outer diameter larger than the final outer diameter of the optical disc to produce a flexible substrate 32a. As shown in FIG. 13B, the flexible substrate 32a is recorded by using an inner ring 50 having a predetermined outer diameter and an outer ring 11 having an inner diameter larger than that of the inner ring 50 so that tension is applied in a radial direction as shown in FIG. The layer 37 is formed. When the recording layer 37 is formed, since the amount of heat applied to the flexible substrate 32a is relatively small, it is possible to prevent deformation by applying a tension to the flexible substrate 32a without attaching the rigidity-imparting substrate 35 to the flexible substrate 32a. good. After the recording layer 37 is formed on the flexible substrate 32a, the recording layer 37 may be processed to a predetermined outer diameter, and the rigidity-imparting substrate 35 may be attached to initialize the recording layer 37.
[0029]
In the above description, the case where the flexible sheet 20 is formed of polycarbonate having a thickness of 75 μm has been described, but the flexible sheet 20 may be formed of polyethylene terephthalate having a thickness of 75 μm or 100 μm.
[0030]
[Comparative Example] The flexible sheet 20 was formed of polycarbonate having a thickness of 75 μm and 100 μm, and after forming the transfer layer 31, the recording layer 37 was formed and initialized without bonding the rigidity-imparting substrate 35 to the flexible sheet 20. As a result, regardless of the thickness, the flexible sheet 20 was significantly deformed by the stress at the time of forming the recording layer 37 and the heat at the time of initialization, and uniform initialization could not be performed. When the flexible sheet 20 is formed of polyethylene terephthalate having a thickness of 75 μm and 100 μm, the recording layer 37 is formed and initialized without bonding the rigidity-imparting substrate 35. The flexible sheet 20 was greatly deformed by the stress when the recording layer 37 was formed and the heat at the time of initialization, and uniform initialization could not be performed.
[0031]
【The invention's effect】
As described above, the present invention provides rigidity on the surface opposite to the transfer surface of the transfer layer on which the pattern of the first stamper provided on one surface of the flexible sheet is transferred, and provides rigidity with a large heat capacity. After attaching the substrate, a recording layer is formed on the transfer surface, a protective layer is formed on the surface of the recording layer, and then the recording layer is initialized. It is possible to prevent the flexible sheet from being deformed by the film forming stress. In addition, when the recording layer is initialized, the heat applied to the flexible sheet can be radiated to the rigidity-imparting substrate, and the flexible sheet can be prevented from being deformed by the heat at the time of initialization. Can be achieved, and good mechanical characteristics can be obtained without fluctuation in reflectance.
[0032]
Further, after forming a pattern of the second stamper on the substrate by injection molding, a recording layer is formed on the surface of the substrate, a protective layer is formed on the surface of the recording layer, and the recording layer is initialized to form a second disk substrate. By manufacturing and bonding the protective layer of the first disk substrate and the protective layer of the second disk substrate, a multilayer optical disk having stabilized recording / reproducing signal characteristics and mechanical characteristics can be manufactured.
[0033]
In addition, a protective sheet that can be peeled off is provided on the surface of the flexible sheet opposite to the transfer layer, and a rigidity-imparting substrate is attached to the protective sheet to form and initialize the recording layer. And the separation of the rigidity-imparting substrate can be facilitated.
[0034]
In addition, the flexible sheet is composed of a continuous web, and after continuously transferring the stamper pattern to form the transfer surface, it can be processed into a disk shape to produce a flexible substrate continuously. In addition, the manufacturing efficiency of the flexible substrate can be improved.
[0035]
Furthermore, when forming the transfer surface on the flexible sheet, an ultraviolet curable resin is applied on the stamper, and a spin-rotating is performed to form an ultraviolet curable resin layer having a predetermined thickness, and the flexible sheet is pressed against the formed ultraviolet curable resin layer. By irradiating ultraviolet rays while forming the transfer surface, a uniform transfer surface can be stably formed.
[0036]
Further, by using a monomer material having no molecular weight distribution as the ultraviolet curable resin, it is possible to reduce the variation in the circumferential thickness of the transfer layer.
[0037]
Furthermore, by making the light transmittance of the flexible sheet and that of the protective sheet equal, it is possible to irradiate the ultraviolet-curable resin layer with ultraviolet light of uniform intensity, and to form a high-quality transfer surface.
[0038]
An optical disk manufactured by this method for manufacturing a multilayer optical disk can obtain good mechanical characteristics without fluctuation in reflectance and can stably obtain high-quality signal characteristics.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of a multi-layer optical disc manufacturing apparatus according to the present invention.
FIG. 2 is a perspective view showing a configuration of an original sheet of a flexible sheet.
FIG. 3 is a configuration diagram illustrating a transfer step.
FIG. 4 is a graph showing a variation characteristic of a film thickness in a circumferential direction of a transfer layer.
FIG. 5 is a cross-sectional view illustrating a configuration of a flexible substrate.
FIG. 6 is a configuration diagram illustrating a rigidity providing step.
FIG. 7 is a perspective view showing a state in which a recording layer is being formed.
FIG. 8 is a process chart showing a protective layer formation, initialization, and peeling steps.
FIG. 9 is a graph showing a temperature change characteristic of a transfer surface with respect to a thickness of a stiffening substrate.
FIG. 10 is a change characteristic diagram of a warp of a first disk substrate with respect to a thickness of a stiffness providing substrate.
FIG. 11 is a perspective view showing a step of bonding a first disk substrate and a second disk substrate.
FIG. 12 is a perspective view showing a configuration of a multilayer disc.
FIG. 13 is a process chart showing another method for forming a recording layer.
[Explanation of symbols]
1; a multi-layer optical disc manufacturing apparatus; 2; a first manufacturing apparatus;
3; second manufacturing apparatus, 4; bonding apparatus, 5; transfer apparatus, 6; outer diameter processing apparatus,
7; rigidity imparting device, 8; film forming device, 9; protective layer forming device,
10; initialization device, 11; peeling device, 12; molding device, 13;
14; protective layer forming device; 15; initialization device; 20; flexible sheet;
21: protective sheet, 22: raw fabric, 23: center hole, 26: stamper,
28; pressing means, 29; ultraviolet irradiation device, 30; ultraviolet curing resin,
31; transfer layer, 32; flexible substrate, 34; adhesive sheet,
35; rigidity-imparting substrate, 36; protective sheet, 37; recording layer, 38;
39; initialization area, 40; first disk substrate, 41; substrate,
42, a recording layer, 43; a protective layer, 44; a second disk substrate,
45: UV curable resin, 46: Multilayer optical disc.

Claims (7)

After attaching a rigidity-imparting substrate having a large heat capacity to a surface opposite to the transfer surface of the transfer layer on which the pattern of the first stamper provided on one surface of the flexible sheet has been transferred, the transfer surface A recording layer is formed on the recording layer, a protective layer is formed on the surface of the recording layer, and then the recording layer is initialized. After the recording layer is initialized, the stiffening substrate is peeled off from the flexible sheet to produce a first disk substrate. And
After a second stamper pattern is formed on the substrate by injection molding, a recording layer is formed on the surface of the substrate, a protective layer is formed on the surface of the recording layer, and the recording layer is initialized to produce a second disk substrate. ,
A method for manufacturing a multilayer optical disk, comprising bonding a protective layer of a first disk substrate and a protective layer of a second disk substrate. 2. The method for manufacturing a multilayer optical disc according to claim 1, further comprising a peelable protective sheet on a surface of the flexible sheet opposite to the transfer layer, and bonding a rigidity-imparting substrate to the protective sheet. 3. The method for manufacturing a multilayer optical disc according to claim 1, wherein the flexible sheet is formed of a continuous raw material, and the preformat of the stamper is continuously transferred to form a transfer surface and then processed into a disk shape. When forming the transfer surface on the flexible sheet, apply an ultraviolet curable resin on the stamper, spin to form an ultraviolet curable resin layer of a predetermined thickness by spinning, and press the flexible sheet against the formed ultraviolet curable resin layer. 4. The method for manufacturing a multilayer optical disk according to claim 1, wherein the transfer surface is formed by irradiating the transfer surface with ultraviolet light. 5. The method according to claim 4, wherein the ultraviolet curable resin is a monomer material having no molecular weight distribution. The method for manufacturing a multilayer optical disc according to claim 4, wherein the flexible sheet and the protective sheet have the same light transmittance. 7. An optical disk manufactured by the method for manufacturing a multilayer optical disk according to claim 1.

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