JP2000090500A - Production of disk-like recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make the joint strength of all disk-like recording media high and uniform while maintaining high productivity. SOLUTION: This process for producing the disk-like recording media consists in joining a pair of disk half bodies 1 formed with at least signal recording layers and/or reflection layers on one main surfaces of disk substrates and formed with protective layers on the outermost layers in such a manner that the protective layers face each other via adhesives. At this time, a plurality of the disks are formed by joining a pair of the disk half bodies 2 via the adhesives. The time integrated values of the pressure applied on the formed plural disks are set approximately constant.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a disk-shaped recording medium such as an optical disk having a signal recording layer such as a phase change layer, and more particularly to a method for manufacturing a disk-shaped recording medium having a pair of bonded substrates. It relates to a manufacturing method.

[0002]

2. Description of the Related Art In the field of information recording, studies on an optical information recording method have been conventionally conducted in various places.
This optical information recording system is capable of non-contact recording and reproduction, achieving a recording density that is at least an order of magnitude higher than that of the magnetic recording system, and can be used in read-only, write-once, and rewritable memory formats. It has a number of advantages such as being able to respond. For this reason, the optical information recording method is considered to be a method capable of realizing an inexpensive large-capacity file for a wide range of uses from industrial use to consumer use.

[0003] Among them, as a read-only recording medium, a digital audio disc on which music information is recorded, an optical video disc on which image information is recorded, and the like are widely used. Magneto-optical disks, phase-change optical disks, and the like have become widespread. on the other hand,
DVD (Digital Versati) for recording various data such as images, music, computer data, etc.
le Disc) is also on the market.

[0004] Each of these optical discs has a configuration in which a recording portion made of a functional film such as a recording layer or a reflective film is formed on a transparent substrate. As a transparent substrate used for an optical disc, polycarbonate, acrylic, epoxy resin, or the like is used in addition to glass. Among them, polycarbonate is most frequently used because of its excellent moldability, dimensional stability, low water absorption and the like.

[0005] Depending on the usage, such an optical disk can be read only from a ROM (Read Only Me) such as a digital audio disk or a video disk.
and a RAM (Random Access Memory) that can perform reproduction, additional writing, and rewriting as required, such as a magneto-optical disk.
y) type.

[0006] The ROM type optical disk is formed by forming concavo-convex prepits having an optical depth of about 1/4 of the wavelength of the reproduction light on a substrate, and forming a reflective film so as to cover the prepits. Configuration. In this ROM type optical disk, reproduction is performed by detecting a change in reflectance due to interference of light generated in the uneven prepits.

A RAM type magneto-optical disk is made of TbFeC.
The recording magnetic film such as an o film is sandwiched between dielectric films for the purpose of preventing oxidation of the recording magnetic layer and enhancing the signal by multiple interference, and has a reflective film covering one main surface side of the recording magnetic layer. The configuration is as follows. RAM like this
In the magneto-optical disk of the type, a region in which the magnetization direction of the recording magnetic film is aligned upward or downward, that is, a recording pit is formed in accordance with information to be written. When the RAM type magneto-optical disk is reproduced, the reproduction light scans the area where the recording pits are formed, and the rotation angle θk (Kerr rotation angle) of the linearly polarized light reflected by the recording pits and the area other than the recording pits. And the difference from the Kerr rotation angle of the linearly polarized light reflected by.

[0008] A RAM type phase change optical disk is a G type optical disk.
The recording phase change layer made of eSbTe film or the like and crystallized in the initialized state is sandwiched by a transparent dielectric film for the purpose of preventing the recording phase change layer from being oxidized and enhancing magneto-optical signals due to multiple interference. And a reflective film that covers one main surface of the recording phase change layer. Then, in such a RAM type phase change optical disc, recording pits in an amorphous state are formed in accordance with information to be written. When reproducing the RAM type phase-change optical disk, the reproduction light scans the area where the recording pits are formed, and detects the difference between the reflectance at the recording pit and the reflectance at the area other than the recording pit. ing.

Incidentally, the above-mentioned DVD uses a light source having a laser wavelength of 635-650 nm for recording and reproduction, and has a thickness of 0.3 mm.
It has a structure in which two recording surfaces of a 6 mm disk are bonded together. Read-only DVD, ie, DVD-RO
There are two types of M disks: an information surface is formed on both disks, and an M disk has an information surface formed only on one disk and the other disk is a dummy disk.

In any of the above cases, the DVD
Is formed by laminating a pair of substrates (about 0.6 mm in thickness). For this reason, DVD
Is configured to have an adhesive between a pair of substrates.

[0011] Then, in this DVD, a pair of discs is bonded by, for example, a hot melt type adhesive,
This is performed using an ultraviolet-curable adhesive, a thermosetting adhesive, or the like. At this time, specifically, the adhesive is formed with a predetermined thickness on at least one of the opposing surfaces of the disks by a roll coating method, a spin coating method, or the like.

[0012]

However, in the case of an optical disk such as a DVD in which a pair of substrates are bonded, it is difficult to reliably join and integrate the pair of substrates while maintaining a predetermined productivity. Was. That is, when bonding a pair of substrates, generally, the bonding strength may change depending on the pressure applied in the direction of bonding the pair of substrates. Therefore, the conventional optical disk manufacturing method has a problem that it is difficult to make the bonding strength of each manufactured optical disk high and uniform while manufacturing a plurality of optical disks with high productivity.

Accordingly, the present invention has been proposed in view of such a conventional situation, and it is possible to maintain high productivity and to make the bonding strength in all disk-shaped recording media high and uniform. An object of the present invention is to provide a method for manufacturing a disk-shaped recording medium.

[0014]

According to a method of manufacturing a disk-shaped recording medium according to the present invention which has achieved the above-mentioned objects, at least a signal recording layer and / or a reflection layer are formed on one main surface of a disk substrate. And a method of manufacturing a disk-shaped recording medium in which a pair of disk halves each having a protective layer formed on the outermost layer are bonded via an adhesive such that the protective layers face each other. A plurality of disks are formed by joining the bodies through an adhesive, and the time integral of the pressure applied to the plurality of disks formed is substantially constant.

In the method of manufacturing a disk-shaped recording medium according to the present invention having the above-described structure, the time integrals of the pressure applied to a plurality of formed disks are made substantially constant. Can have substantially the same bonding strength.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a specific embodiment of a method for manufacturing a disk-shaped recording medium according to the present invention will be described with reference to the drawings.

The method of manufacturing a disk-shaped recording medium according to the present embodiment employs a phase change method as a recording method as shown in FIG. 1, and is used for manufacturing a RAM type optical disk 1 conforming to the so-called DVD standard. Method.

The optical disk 1 shown in FIG. 1 is formed in a substantially disk shape, and is formed by joining a pair of disk halves 2 via an adhesive layer 3 made of an adhesive. These disk halves 2 include a transparent substrate 4 made of injection-molded polycarbonate or the like having a disk diameter of about 120 mm and a thickness of about 0.6 mm, and a first dielectric film 5 made of ZnS-SiO _2. , a phase change recording film 6 made of GeSbTe or the like, the second dielectric film 7 made of ZnS-SiO ₂
And a reflective film 8 made of Al or the like are laminated in this order, and a protective film 9 made of an ultraviolet curable resin or the like is formed on the reflective layer 8. This optical disk has a center hole formed at a substantially central portion thereof and having a predetermined inner diameter.

Here, the protection film 9 is formed on the reflection film 8 by using, for example, an acrylic ultraviolet curing resin. Specifically, as shown in FIG. 2, the protective film 9 is formed by a spin coating method using a spin coating device. The spin coater has a turntable 10 for rotating a disk, and a nozzle 12 for supplying an acrylic ultraviolet curing resin 11. The nozzle 12 is attached to one end of a resin supply pipe 13 connected to a resin supply unit (not shown). In this spin coating apparatus, the acrylic ultraviolet curable resin 11 stored in the resin supply section is discharged from the nozzle 12 through the resin supply pipe 13.

When the protective layer 9 is formed using the spin coater configured as described above, the disk half 2 is
It is placed on the turntable 10 so that the surface on which the reflective layer 8 is formed faces upward. Then, while the turntable 10 is rotated at a low speed, the acrylic ultraviolet curable resin 11 is disposed near the substantially central portion of the reflective layer 8 of the rotating disk half 2.
Supply. After that, the acrylic UV curable resin 11 is coated on the entire surface of the reflective layer 8 and the excess acrylic UV curable resin 11 is shaken off by the centrifugal force generated by rotating the turntable 10 at high speed.

Then, as shown in FIG. 3, the protective layer 9 is formed by curing the acrylic ultraviolet curable resin 11 by irradiating ultraviolet rays.

The optical disk 1 is formed by laminating the pair of disk halves 2 configured as described above, as will be described in detail later. At this time, the pair of disk halves 2 are bonded together using, for example, a slow-hardening adhesive such as a cationic ultraviolet curing resin.

In order to bond the pair of disk halves 2, first, an adhesive made of an epoxy-based slow-hardening ultraviolet curable resin is applied to the surface on which the protective layer 9 is formed by a screen printing method. In this screen printing method, as shown in FIG. 4, a printing screen 15 having a mesh structure is placed on the protective layer 9, and an epoxy-based slow-curing ultraviolet curable resin B is supplied onto the printing screen 15. The squeegee 16 is moved in the direction of the middle arrow a. Thus, the adhesive 17 made of the epoxy-based slow-hardening ultraviolet-curable resin B can be uniformly formed on the protective layer 9 with a predetermined thickness. At this time, the adhesive 17 is formed on at least one of the pair of disk halves 2 to be bonded.

Next, as shown in FIG. 5, the adhesive 17 is irradiated with ultraviolet rays. At this time, the disk half 2
It is placed directly under the ultraviolet lamp 18 so that the surface on which the adhesive 17 is formed faces upward, and ultraviolet rays are uniformly irradiated.
Here, the adhesive 17 made of an epoxy-based slow-curing ultraviolet-curable resin is gradually cured by being irradiated with ultraviolet rays.

Next, as shown in FIG. 6, the pair of disk halves 2 in which the curing process of the adhesive 17 has started is removed.
Lay them so that they face each other. At this time, the pair of disk halves 2 are positioned and superposed on each other so as to face each other accurately by the center shaft 18, and are pressed from above and below by press tables 19 and 20 for several seconds. Here, the opposing adhesives 17 can be bonded to each other because they are not completely cured even after being irradiated with ultraviolet rays. Hereinafter, the step of overlapping the pair of disk halves 2 is referred to as a close contact pressing step.

Next, as shown in FIG. 7, in order to completely cure the adhesive 17 made of an epoxy-based slow-curing ultraviolet-curing resin, the pair of disk halves 2 which are in close contact with each other are carried into a curing press 21. The pair of disk halves 2 adhered through the adhesive 17 are separated by the curing press 21 into the adhesive 1.
7 is pressed until it is completely cured, and is completely bonded.

As shown in FIG. 7, the curing press 21 has a plurality of weight plates 22 on which a pair of disk halves 2 closely contacted as described above are placed on one main surface 22a. Loading means (not shown) for placing the weight plates 22 on a plurality of weight plates 22 stacked together and unloading means 2 for discharging the weight plates 22 stacked together.
3 is provided. This weight plate 22 is shown in FIGS.
As shown in FIG. 1, one main surface 22a is slightly larger than the main surface of the optical disc 1 and has a convex portion 24 formed substantially at the center of the one main surface 22a and passing through the center hole of the optical disc 1. I have. In the weight plate 22, a fitting projection 25 is formed on the projection 24, and a fitting recess 26 that fits with the fitting projection 25 is formed substantially at the center of the other main surface 22b. ing. Further, the weight plate 22 has a concave portion 27 formed on the peripheral surface thereof, which is easily held by a carrying-in means, a carrying-out means, and an operator.

In the curing press 21 thus constructed, first, the pair of disk halves 2 carried out through the close pressing step are accurately passed through the center hole of the disk halves 2 through the convex portions 24. Is placed on the weight plate 22 in a state where it is positioned at the position. Then, a plurality of weight plates 22 on which the pair of disk halves 2 adhered in this manner are placed are superposed as shown by an arrow c in FIG. At this time, the upper and lower weight plates 22 are fitted with the fitting projections 25 of the lower weight plate 22.
And the fitting recess 26 of the weight plate 22 located above are fitted together.

After the predetermined number of weight plates 22 are overlaid, the lowermost weight plate 22 is carried out as shown by an arrow d in FIG. At this time, the lowermost weight plate 22 is easily transported out by the unloading means 23 moving the overlapped weight plates 22 other than the lowermost layer in the direction e in FIG.

When another weight plate 22 is overlaid, the lowermost weight plate 22 is carried out as described above. Thus, the curing press 2
In 1, always a certain number of weight plates 22 are superimposed,
The pair of disk halves 2 placed on one main surface 22a are subjected to curing press by the plurality of weight plates 22 stacked thereon.

By the way, some adhesives have a relationship between the curing press time (referred to as “curing time”) and the adhesive strength, for example, as shown in FIG. in this case,
After a predetermined time has elapsed, the bonding strength no longer depends on the curing time. Also, as shown in FIG.
In such an adhesive, the bonding strength depends on the pressure of the curing press (referred to as “curing pressure”).

For this reason, when a plurality of optical disks 1 are manufactured, by applying a curing pressure substantially uniformly in a curing press performed on a pair of disk halves 2 after the close contact pressing step, The optical disc 1 having a uniform bonding strength can be reliably manufactured.

In the curing press 21 described above, assuming that the mass of the pair of disk halves 2 is m, the mass of the weight plates 22 is M, and the number of stacked layers is n, the pair of discs mounted on the lowermost weight plate 22 The force F1 applied to the disk half 2 is F1 = (n-1) × (m + M), and is placed on the weight plate 22 located at an arbitrary s-th stage (0 <s ≦ n). The force Fs applied to the pair of disk halves 2 is Fs = (ns) × (m + M).

As described above, in the curing press 21 described above, the pressure applied to the pair of disk halves 2 greatly differs depending on the position where the weight plates 22 are overlapped. However, in this curing press machine 21, since the weight plate 22 located at the lowermost layer is carried out, the pressure applied to the pair of disk halves 2 placed on the weight plate 22 to be carried out is lower than that in FIG. It is shown as follows.

The plurality of disk halves 2 that have been cured and pressed by the curing press 21 have substantially constant pressure integrated values over time. For this reason, in the curing press 21, the adhesive strength of the plurality of cured optical disks 1 can be made uniform. At this time, since the pair of disk halves 2 are brought into close contact with each other at substantially constant time intervals, that is, the time required for the new weight plates 22 to be superposed is substantially constant. The halves 2 are all pressed for a substantially uniform period.

In this method, since the concave portion 27 is formed on the side surface of the weight plate 22, the lowermost weight plate 22 can be easily held and carried out by the concave portion 27. Furthermore, this weight plate 22 has one main surface 22 thereof.
a and the other main surface 22b are preferably flattened with high precision. As described above, by flattening the one main surface 22a and the other main surface 22b of the weight plate 22 with high precision, the surface of the cured optical disk 1 is flattened with high precision. For this reason, the optical disc 1 manufactured by this method is prevented from being deformed,
It is possible to suppress adverse effects due to acceleration during recording and reproduction.

Further, according to the above-described method, a pair of disk halves 2 having passed through the close pressing step are sequentially placed on a curing press 21.
Then, the optical discs 1 which are completely bonded can be sequentially manufactured. For this reason, according to this method, the optical disc 1 joined reliably and with uniform joining strength can be manufactured with high productivity.

Incidentally, the method of manufacturing a disk-shaped recording medium according to the present invention is not limited to the method using the curing press 21 as described above. For example, an inverting curing press 30 as shown in FIG. It may be what was.

The reversing curing press 30 presses the fitting projection 25 of the uppermost weight plate 22 in a state where a plurality of weight plates 22 on which a pair of disk halves 2 closely adhered are mounted are superposed. The upper shaft presser 31, the lower shaft presser 32 that presses the fitting concave portion 26 of the lowermost weight plate 22, and the plurality of weight plates 22 pressed by the upper shaft presser 31 and the lower shaft presser 32 are moved to the upper shaft presser 31 and the upper shaft presser 31. A reversing mechanism 33 for reversing the upper and lower parts together with the lower shaft holder 32 is provided.

In the reversing curing press 30 constructed as described above, first, the first weight plate 22 is fitted into the fitting recess 2.
6 is fitted to the lower shaft retainer 32. Then, the weight plates 2 are sequentially overlapped, and the upper shaft holder 32 is fitted to the fitting projection 25 of the last weight plate 22. At this time, the pair of disk halves 2 that are in close contact with each other are not placed on the last weight plate 22.

Thereafter, when approximately half of the predetermined curing time has elapsed, the plurality of weight plates 22 are turned upside down together with the upper shaft presser 31 and the lower shaft presser 32. When the remaining half of the predetermined curing time elapses in the upside down state, the pair of disk halves 2 sandwiched between the stacked weight plates 22 are completely bonded.

At this time, since the reversing curing press 30 is turned upside down when approximately half of the predetermined curing time has elapsed, the relationship between the progress of the curing time and the transition of the curing pressure is shown in FIG. As shown. As can be seen from FIG. 13, before turning upside down, the pair of disk halves 2 located on the uppermost layer, the pair of disk halves 2 located on the lowermost layer, and the pair of disk halves 2 located on the middle stage are: The time integrals of the pressures are substantially equal. For this reason, even when the reversing curing press 30 is used, the pair of disk halves 2 is cured with substantially uniform pressure regardless of the position where the disk halves 2 are overlapped. Therefore, even with this method, an optical disk in which the pair of disk halves 2 are bonded with a substantially constant bonding strength can be formed reliably and easily.

Further, even when the reversing curing press 30 is used, the paired disk halves 2 having been subjected to the contact pressing step are sequentially carried in and superposed, so that the completely bonded optical disk 1 can be moved to a predetermined position. A plurality can be manufactured within the curing time. For this reason, according to this method, the optical disc 1 joined reliably and with uniform joining strength can be manufactured with high productivity.

When the reversing curing press 30 is used, the reversing is repeated up and down during a predetermined curing time, so that the overlapped weight plate 22 is substantially equal to the upward time and the downward time. Is also good. Also in this case, substantially the same pressure can be applied to all the pair of disk halves 2 irrespective of the positions of the pair of disk halves 2. Therefore, according to this method, it is possible to reliably and easily form an optical disk in which the pair of disk halves 2 are bonded with a substantially constant bonding strength.

[0045]

As described above in detail, according to the method of manufacturing a disk-shaped recording medium according to the present invention, the method is applied to a disk formed by joining a pair of disk halves via an adhesive. The time integral value of the pressure is substantially constant. Therefore, according to this method, the joining strength of the pair of disk halves can be made substantially constant among the plurality of disks. Therefore, according to this method, it is possible to maintain high productivity and to make the bonding strength in all the disk-shaped recording media high and uniform.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a main part of a phase-change optical disk shown as an example of a disk-shaped recording medium manufactured by a method for manufacturing a disk-shaped recording medium according to the present invention.

FIG. 2 is a perspective view of a main part of a spin coater schematically showing a state in which a protective layer is formed by a spin coat method.

FIG. 3 is a perspective view of a main part of an ultraviolet irradiation device schematically showing a state in which the protective layer is irradiated with ultraviolet light.

FIG. 4 is a perspective view of a main part of a printing screen schematically showing an aspect in which an adhesive is applied on a protective layer by a screen printing method.

FIG. 5 is a perspective view of a main part of an ultraviolet irradiation device schematically showing a state in which the adhesive is irradiated with ultraviolet light.

FIG. 6 is a perspective view of a main part of a close-contact press device for pressing a pair of disk halves in close contact;

FIG. 7 is a schematic view of a curing press.

FIG. 8 is a perspective view of the weight plate as viewed from one principal surface direction.

FIG. 9 is a perspective view of the weight plate as viewed from the other principal surface direction.

FIG. 10 is a characteristic diagram showing a relationship between a curing time and an adhesive strength.

11 is a characteristic diagram showing the relationship between the curing time and the pressure applied to a pair of disk halves when the curing press shown in FIG. 7 is used.

FIG. 12 is a schematic view of a reversing curing press used in another embodiment of the method for producing a disk-shaped recording medium according to the present invention.

13 is a characteristic diagram showing the relationship between the curing time and the pressure applied to a pair of disk halves when the reversing curing press shown in FIG. 13 is used.

[Brief description of reference numerals]

1 optical disk, 2 disk half bodies, 3 adhesive layers, 21
Curing press machine, 22 weight plate

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[Procedure amendment]

[Submission date] November 6, 1998 (1998.11.
6)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0008

[Correction method] Change

[Correction contents]

[0008] A RAM type phase change optical disk is a G type optical disk.
The recording phase change layer made of an eSbTe film or the like and crystallized as an initialized state is sandwiched by a transparent dielectric film for the purpose of preventing the oxidation of the recording phase change layer and enhancing the signal due to multiple interference. The phase change layer is configured to include a reflective film that covers one main surface of the phase change layer. Then, in such a RAM type phase change optical disc, recording pits in an amorphous state are formed in accordance with information to be written. When reproducing the RAM type phase-change optical disk, the reproduction light scans the area where the recording pits are formed, and detects the difference between the reflectance at the recording pit and the reflectance at the area other than the recording pit. ing.

Claims (7)

[Claims] 1. A pair of disk halves each having at least a signal recording layer and / or a reflective layer formed on one main surface of a disk substrate and a protective layer formed as an outermost layer,
In a method of manufacturing a disk-shaped recording medium in which protective layers are bonded to each other with an adhesive so as to face each other, a plurality of disks are formed by bonding the pair of disk halves with an adhesive. A time-integrated value of the pressure applied to the disc is substantially constant. 2. The method for manufacturing a disk-shaped recording medium according to claim 1, wherein the formed disks are sequentially superimposed on each other, and after a lapse of a predetermined time, the disk disposed in the lowermost layer is taken out. 3. The method for manufacturing a disk-shaped recording medium according to claim 2, wherein said disks are sequentially superimposed on each other via a weight plate. 4. The method for manufacturing a disk-shaped recording medium according to claim 1, wherein the formed disks are sequentially superimposed on each other, and turned upside down when approximately half of a predetermined time has elapsed. 5. The formed discs are sequentially superimposed on each other, and repeatedly turned upside down after a predetermined time has elapsed, so that the time when the superposed discs are upward and the time when they are downward are substantially the same. 2. The method for manufacturing a disk-shaped recording medium according to claim 1, wherein: 6. The method according to claim 1, wherein the adhesive is a slow-hardening adhesive. 7. The method for producing a disk-shaped recording medium according to claim 6, wherein the slow-hardening adhesive is a cationic ultraviolet curable resin.