JPH0438731A - Production of optical recording medium - Google Patents

Abstract

PURPOSE:To increase the rotating speed of the optical recording medium and to speed up a transfer rate by joining two sheets of disk substrates while supporting the inner peripheral part of the one disk substrate and sticking the substrates in the state of not generating unequal contact and strains by a substrate supporting member in the outer peripheral part at the time of sticking the disks substrates to each other. CONSTITUTION:The disk substrate 1 is mounted and fixed onto a fixing supporting base 3 for substrates. A central hole 6 is formed in the central part of the disk substrate 2 and the central part 8 at the front end of an air cylinder 4 sucks the substrate 2 and inserts the same into the central 6, thereby positioning the substrate 2. After the substrates 1, 2 are set, the air cylinder 4 is lowered at >=50mm/sec speed to put the substrates 1, 2 into the tentatively stuck state in which the respective adhesive layers come into contact. The substrates are, thereupon, set to a press machine and are subjected to adhesion under pressurization. The uniformity at the time of sticking the outermost peripheral part is improved. The rotating speed of the disk is greatly increased in this way and the transfer rate is greatly improved.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a method for manufacturing an optical recording medium that can handle high-speed information transfer. The present invention relates to a method of manufacturing an optical recording medium.

(Prior Art) Optical recording media have many advantages, such as their large recording capacity and the ability to record and reproduce signals in a non-contact manner.
It has been put into practical use as laser discs, compact discs, large-capacity data file discs, optical memory cards, etc. As described above, most of the devices currently in practical use are disk-shaped, and are usually made of a transparent disk substrate made of glass, plastic, etc., with a thin film recording layer formed on it. Optical discs are classified into read-only types, write-once types, rewritable types, etc. Magneto-optical disks, which have been attracting attention in recent years, belong to this type of rewritable disk, and because their recording layer uses materials such as rare earth transition metals that are easily oxidized, two disk substrates are bonded together with an adhesive, with the recording layer inside. It is considered desirable to protect the recording layer from the outside air. Note that it is preferable to form a recording layer on each of two disk substrates that are bonded together to form a double-sided recording type, since this can double the recording capacity.

By the way, a double optical disc is mounted on a spindle, and in the case of constant angular velocity (CAV), for example, 1.8
It is rotated at a constant speed of about 0 rpm, and in this state, recording and reproduction of signals is performed by the optical head. However, due to the large capacity of optical discs, it is necessary to increase the transfer rate, especially when transferring signals in bulk.
For this reason, it is being considered to increase the rotational speed of the disk.

However, as the rotational speed of the disk becomes faster, the vertical acceleration of the disk surface due to this rotation, so-called surface runout acceleration, increases (the surface runout acceleration is proportional to the square of the rotational speed), and the focus servo increases. It becomes easy to come off. In other words, for example, if the disk rotation speed is doubled in order to double the transfer rate, the surface runout acceleration will be four times that of the conventional one. Therefore, in order to increase the transfer rate, it is necessary to It is necessary to keep the amount of warpage small. This kind of warpage of the disk substrate occurs during disk substrate molding or disk substrate bonding.In order to reduce the amount of warpage during disk substrate molding, the molded substrate is heated in a high temperature atmosphere. A technique for removing molding distortion by annealing is known (for example, JP-A-62-252548 and JP-A-62264483).

(Problem to be Solved by the Invention) However, although the above-mentioned conventional technology was effective in reducing the amount of warpage in a so-called single-plate state of a single disk substrate, it It is not possible to remove the warpage of the disk substrate that occurs, and as a result, it is difficult to significantly reduce the amount of substrate warpage after the disk substrates are bonded together. Therefore, it has been difficult to significantly increase the disk rotational speed and furthermore to significantly improve the transfer rate using the above-mentioned conventional techniques.

The present invention was made in view of the above circumstances, and provides an optical recording medium in which the amount of warpage of the substrate is small in a method of manufacturing an optical disk by bonding two disk substrates together, and the surface runout acceleration during recording and playback can be reduced. The purpose of this invention is to provide a method for manufacturing.

(Means for Solving the Problems) A method for manufacturing a first optical recording medium of the present invention includes a first transparent disk substrate having a recording layer formed on one side, and a first disk substrate substantially identical to the first disk substrate. A second disc substrate of the same shape is placed facing the recording layer with the recording layer inside, and an adhesive is applied to the side of at least one of these two disc substrates that faces the other, and then the two discs are Moving one of the substrates so as to approach the other while supporting only its inner peripheral portion, thereby bringing the two disk substrates into contact with each other and temporarily fixing them, and then applying pressure to bond these two disk substrates together. It is characterized by:

Furthermore, the second method for manufacturing an optical recording medium of the present invention includes:
The first method for manufacturing an optical recording medium described above is characterized in that the moving speed of the moving disk substrate is 50 s/sec or more.

Note that the above-mentioned "recording layer" may be formed on both of the two disk substrates, or may be formed only on one of them.

(Function) Conventionally, in the process of laminating disk substrates, one disk substrate is fixed, the other disk substrate is moved while being supported by a substrate support member, and the two disk substrates are brought into contact (temporarily) through an adhesive. The two disk substrates are pressed together from this temporary bonded state to perform bonding, and the substrate support member supports not only the inner periphery but also the outer periphery of the disk substrate, Further, it is considered that the substrate portion supported by this substrate support member is likely to cause uneven contact or distortion when the two substrates are in contact with each other.

On the other hand, especially in optical recording media manufactured by bonding two disk substrates together, surface runout acceleration is generally large near the outermost periphery, and this is the divine rule for increasing rotational speed.

Therefore, in the above-described configuration, the substrate support member supports only the inner peripheral portion of the disk substrate, and does not support the outer peripheral portion of the disk substrate, which tends to have a large influence on the surface runout acceleration due to the support of the substrate support member. In other words, by performing lamination in a state where uneven contact or distortion due to the support of the substrate support member does not occur at least in the outer peripheral portion, the amount of disk warpage in the outer peripheral portion after lamination is reduced, and the optical recording medium is The maximum surface runout acceleration can be reduced, thereby increasing the rotational speed and the transfer rate.

Furthermore, when the two disk substrates are brought into contact with each other, the outer periphery of the moving disk substrate warps slightly in the opposite direction to the direction of movement, and this causes the outer periphery of the two disk substrates to bend when temporarily fastened. It is thought that the uniformity of contact between parts increases. In addition, the higher the moving speed of the disk substrate, the larger the above-mentioned warping amount becomes.
/see or more, the amount of warpage that can increase the above-mentioned contact uniformity can be obtained, so the configuration described in item 1 can further reduce the surface runout acceleration of the optical recording medium.

(Example) Hereinafter, a method for manufacturing an optical recording medium according to an example of the present invention will be described with reference to the drawings.

FIG. 1 and FIG. 2 are schematic diagrams for explaining the method of this embodiment. In the method of this embodiment, first, as shown in FIG. 1, a first disk substrate 1 and a second disk substrate 2 are opposed to each other with a predetermined distance A apart. That is, the first disk substrate 1 is placed on the substrate fixing support 3, and the second disk substrate 2 is placed above the first disk substrate 1 under vacuum by the air cylinder 4. Each is held in place by adsorption. Note that the above A is, for example, 35 chu. The two disk substrates 1 and 2 mentioned above are made by laminating a magneto-optical recording layer and an organic resin protective layer in this order on a polycarbonate substrate with a diameter of 1.30 mm and a thickness of 1.2#, on which a guide groove is formed. be. Further, a hot melt adhesive is applied onto the organic resin protective layer using a roll coater. Furthermore, as shown in FIG. 1, both disk substrates 1.2 are oriented such that their respective magneto-optical recording layers face each other. Note that a central hole 5.6 is formed in the center of both the disk substrates 1 and 2. The air cylinder 4 is a cylindrical member with a diameter of about 20 mm at the tip and has a plurality of air suction holes 7 on the outer periphery of the tip. It has become.

The center portion 8 of the tip of the air cylinder 4 has a convex shape, and is inserted into the center hole 6 of the substrate 2 when air is sucked into the disk substrate 2, thereby positioning the substrate 2. .

After setting the two disk substrates 1 2 as described above, the air cylinder 4 is lowered in the direction of arrow B at a speed of about 100 s/sec by a cylinder drive unit (not shown) to set the two disk substrates 1 . .2 gradually approach the two disk substrates 1 and 2 as shown in FIG.
The lowering of the air cylinder 4 is stopped while the two are in contact with each other. At this time, the two disk substrates 1 and 2 are in a temporary state where their respective adhesive layers are in contact with each other, and in this state, a press machine (not shown) is loaded with Cera t・L 5 Kg/c.
Pressure bonding is performed at a press pressure of rA.

By the way, in the method of this embodiment, as shown in FIG. 1, the movable disk substrate 2 is suction-supported only on its inner circumferential side, and its outer circumferential side is in a free state. , 2 are joined together, the outer periphery is not supported at all by a support device, which can cause dimensional non-uniformity or distortion.

In addition, the moving speed of the movable disk substrate 2 is set to 100 s/sec, and during this movement, the disk substrate 2 is subjected to air resistance and, although slightly, the outer periphery of the disk substrate 2 is bent upward into a bowl shape. By doing so, when the two disk substrates 1 and 2 are bonded together, the bonding progresses from the inner circumferential portion toward the outer circumferential portion. This improves the uniformity when bonding the outermost portion.

Note that the method for manufacturing the optical recording medium of the present invention is not limited to the above-described embodiments, and various other modifications are possible. Of course, the members that support the substrate are not limited to those shown in the drawings. Further, for example, in the embodiment described above, only one disk substrate 2 is moved, but it is also possible to move both disk substrates so that they are brought closer to each other. In addition, in order to obtain the effect of uniformity of bonding by warping the outer periphery, the above-mentioned moving speed needs to be 50 mm/sec or more, and considering the strength of the substrate and device, etc., it should be 100 to 200 mm/sec. It is desirable that the

Further, the thickness of the adhesive layer of the optical recording medium mentioned above is 160 μm or less, preferably 100 μm or less from the viewpoint of adhesive strength. Furthermore, as the adhesive used for this adhesive layer, various conventionally known adhesives can be used, including hot melt adhesives.

Ultraviolet curing adhesives and epoxy adhesives are preferable, and hot melt adhesives are particularly preferable because they are suitable for mass production and have fewer problems in terms of toxicity to the human body. Further, specific examples of this adhesive include, for example, synthetic rubber adhesive #XW-13 manufactured by Toagosei Kagaku Co., Ltd.; and ultraviolet curable adhesive L I-978 manufactured by LOCTITE.

Nagase-CIBA ultraviolet curing adhesive XN
R5490 can be used.

Further, the shape and dimensions of the disk substrates 1 and 2 of the optical recording medium can be determined by various standards. For example, as a substrate of a 5.25-inch magneto-optical recording medium, , thickness, 2mm, outer diameter 13
0 mm and an inner diameter of 15 m.

In addition to the above-mentioned polycarbonate, materials such as polymethyl methacrylate, epoxy resin, and glass are used as materials for the disk substrates 1 and 2. Among these, substrates made of plastics such as polycarbonate, polymethyl methacrylate, and epoxy resin are preferred, and in particular, Polycarbonate is more preferred since it has advantages such as low water absorption and high glass transition point.

In the embodiment described above, recording layers are provided on both disk substrates, but it is of course applicable to a case where a recording layer is provided on either one of the disk substrates.

Note that the press pressure when bonding under pressure using the above-mentioned press machine can be 0.5 to LOKg/crj, preferably 4 to 7 Kg/crl.

Note that various oxides and metal magnetic materials can be used as the above-mentioned magneto-optical recording layer. For example, Mn Aj!
Crystal materials such as Ge, Mn Cu Bi, GdIG,
Bi 5IDEr Ga IG, Bi Sm Y
bC.

It is an amorphous layer mainly composed of a single crystal material such as Ge1G, as well as transition metals and rare earth metals, and its form may be a single layer or two or more layers of alternating thin films of different magnetic materials. It may be a laminated layer. Among them, a recording layer mainly composed of transition metals and rare earth metals is particularly preferable from the viewpoint of characteristics; for example, Fe, Co, Ni, etc. are used as the transition metals, and Tb, Gd, Nd, Dy, Sn+, etc. are used as the rare earth metals. be able to. Specific examples of the composition of the magneto-optical recording layer include Gd Co, Gd Fe, and Tb Fe.

Dy Fe, Gd FeTb, Tb Fe Co, Dy
FeCo, TbFeNi, GdFeCo
, NdDyFeCo, and the like. Among them, Tb
FeC.

is most preferable, and in order to further improve the corrosion resistance of the recording layer, it is preferable to contain Cr, Ta, AJ, PL, V, etc. Among them, Cr is the most effective, and its content is 2. The content ranges from 3 to 20 at%, preferably from 3 to 5 at%. Note that the magneto-optical recording layer is formed by a vacuum film-forming method such as a sputtering method, and has a film thickness of 200 to 3,000 layers. Further, usually, a dielectric thin film is formed between the magneto-optical recording layer and the substrate as an enhancement layer of the recording layer. Then, an inorganic protective layer for protecting this recording layer is formed on the magneto-optical recording layer. Examples of the materials for the enhancement layer and the inorganic protective layer include St Ox and St Nx.

AJ! Dielectrics such as oxides, nitrides and sulfides such as Nx and Zn'S are used. Among them, optical properties,
From the viewpoint of protective function, nitride of Sl, nitride of A'' or a mixture thereof is preferable. Furthermore, C/N can be further improved by providing a metal reflective layer on the inorganic protective layer. The material of the metal reflective layer is a thin metal film with a thickness of 300 to 600 mm, mainly made of 81, Ni, etc., and is deposited by the sputtering method like the other layers. Although there are no particular limitations on the film-forming conditions for the enhancement layer and the protective layer, the film thickness is usually 800 to 1,300 for the enhancement layer, and 200 to 1,500 for the inorganic protective layer.
There are 00 people. Furthermore, in order to improve the characteristics of the magneto-optical recording layer, a metal reflective layer of 300% was added on the inorganic protective layer.
It is also possible to form a film with a thickness of 600 to 600.

After forming a magneto-optical recording layer consisting of thin films such as the above-mentioned recording layer, enhancement layer, inorganic protective layer, and metal reflective layer, the top and side surfaces of the layer are coated with an organic resin protective layer such as an ultraviolet curing resin. It is also possible to further improve the storage stability of the recording medium.

When the optical recording medium is a write-once type (WO type), the recording layer thereof is Te, Te C, Te Se.

TeC3z, Te5ePb, Te-TeO2, SbS
Metal thin films such as e, Te Se As , Te Ge, etc., cyanine, merocyanine, phthalocyanine, methine dyes or their derivatives, and dye thin films such as benzenethiol nickel complexes and tetrahydrocholine complexes may also be used. Then, to improve recording performance, an overcoat layer is formed using a subbing layer such as a thin metal film, a dielectric material, or an organic material, and a dielectric film such as 5i02 to improve corrosion resistance, or a sandwich structure is formed by sandwiching the recording layer. It can be done. The thickness of the recording layer is usually 500 to 1200.

When the optical recording medium is a read-only type (ROM type), its recording layer is usually a thin metal film with a high reflectance, and is made of Au2.
．． Au, Pt, Ta, Cr, Ni.

A single substance or alloy such as T1 is used, and among them, A1 or Af!, which is particularly low in cost and has a relatively good reflectance, is used. Alloys are preferred. The thickness of the recording layer is 500 to 1500 layers.

] 6 Next, in order to explain the method of the present invention more specifically, Examples a, b, c and a comparative example were carried out under the conditions shown below, samples of magneto-optical disks were prepared for each, and then, for each sample, The surface runout acceleration was measured. The measurement results are shown in the table below.

Example-a A polycarbonate substrate having a diameter of 30 mm and having a guide groove formed therein by injection molding was used, and this polycarbonate substrate was set on a rotating substrate holder disposed in a sputtering chamber of a magnetron sputtering device.

Then, argon gas was introduced into the sputtering chamber, and the gas pressure was set to 1 mTorr.

Then, a thin film of SiNx with a thickness of 1.100 nm was first formed as an enhancement layer by magnetron sputtering.

Next, a Fe Co Cr alloy target and Tb
Tb, 5F (468CO8C
A recording layer consisting of rs was deposited to a thickness of 240 mm.

After that, an inorganic protective layer of SiN is formed on the recording layer.
A thin film of x was formed to a thickness of 250.

Furthermore, A, R-Ta (Ta
A magneto-optical recording layer having a four-layer structure consisting of an enhancement layer, a recording layer, an inorganic protective layer and a metal reflective layer was formed on the substrate by forming a thin film of 5 at %) to a thickness of 600 layers.

After that, Dainippon Ink Co., Ltd. was applied on the magneto-optical recording layer.
UV curing resin #5D-17 was coated with 30% by spin code method.
It was coated to a thickness of 5 μm under the conditions of 00 rpm+, and cured by irradiating ultraviolet rays on the substrate using a high-pressure mercury lamp under the conditions of 100 mW/c#ix for 1 minute to form an organic resin protective layer.

Under similar conditions, another medium was prepared in which the magneto-optical recording layer was provided on one side of a substrate of the same shape, and each of the substrates was placed with the side without the magneto-optical recording layer facing outward, and the organic resin was protected. Hot melt adhesive #XW manufactured by Toagosei Kagaku Co., Ltd. on the layer
Melt -13 at 150℃ and use a roll coater to coat 50μ
It was applied to a thickness of m.

A jig shown in FIG. 1 was used as a bonding jig for temporarily bonding these pieces together before pressure bonding them. That is, first, one disk substrate 1 coated with adhesive is placed on the disk substrate mounting table 3, and the other disk substrate 2 coated with adhesive is vacuum-adsorbed to the tip of the air cylinder 4. This air cylinder 4 was lowered at a speed of 50 mm/sec and joined to the disk substrate 1 for temporary fixing.

Thereafter, they are bonded under pressure using a press machine with a press pressure of 5 kg/cr/r. The surface runout acceleration of the magneto-optical disk sample obtained in this way was measured using a LM-1 manufactured by Ono Gane.
Measured by 00. Disc rotation speed to 180°rpm
The measurement was performed at a position BOmm from the center of the disc.

Example - The moving speed of the movable side during temporary bonding is 100 m/sec
A double-sided recording type magneto-optical disk was prepared under the same conditions as in Example-a except for the following conditions. Thereafter, the same measurements as in Example-a were performed on this sample.

Example-0 A double-sided recording type magneto-optical disk was prepared under the same conditions as Example-a, except that the moving speed on the movable side during temporary bonding was 40 m/sec. Thereafter, the same measurements as in Example-a were performed on this sample.

Comparative Example A double-sided recording type magneto-optical disk was prepared under the same conditions as in Example-a except that an air cylinder capable of vacuum suction not only on the inner circumference but also on the outer circumference was used as the jig used for temporary bonding. After this, Example-a for this sample
Measurements similar to those were performed.

(Table) (Effects of the Invention) As described above, according to the first method of manufacturing an optical recording medium of the present invention, when bonding two disk substrates together, at least one disk substrate is bonded only to its inner peripheral portion. Both disk substrates are bonded together by supporting them, and the bonding is performed in such a way that there is no uneven contact or distortion caused by the substrate support member at the outer periphery, so the outer periphery after bonding is By reducing the amount of disk warpage, it is possible to reduce the maximum surface runout acceleration of the optical recording medium, thereby increasing the rotation speed and transfer rate.

Further, according to the second method of manufacturing an optical recording medium of the present invention, the moving speed of the moving disk substrate is set to 50 #/sec or more, and the outer peripheral portion of the disk substrate is warped to prevent the bonding when bonding the two disk substrates. Since the bonding progresses from the inner circumferential side to the outer circumferential side, the bonding uniformity between the outer circumferential portions of both disk substrates increases, thereby further reducing the maximum surface runout acceleration of the optical recording medium. It becomes possible to significantly increase the rotation speed and significantly increase the transfer rate.

[Brief explanation of drawings]

1 and 2 are schematic cross-sectional views for explaining the method of manufacturing an optical recording medium according to an embodiment of the present invention, of which FIG. 1 shows the initial setting, and FIG. 2 shows the process of bonding the disk substrates. FIG.

Claims (2)

[Claims] (1) A transparent first disk substrate having a recording layer formed on one side and a second disk substrate having substantially the same shape as the first disk substrate are placed facing each other with the recording layer inside, and Adhesive is applied to the side of at least one of the two disk substrates facing the other, and then one of the two disk substrates is moved to approach the other while supporting only its inner peripheral portion. . A method of manufacturing an optical recording medium, characterized in that the two disk substrates are brought into contact with each other and temporarily fixed, and then the two disk substrates are bonded together by applying pressure. (2) The speed of movement of the moving disk substrate is 50 m.
2. The method for manufacturing an optical recording medium according to claim 1, wherein the speed is at least m/sec.