JPH0410242A - Optical information recording medium and production thereof - Google Patents

Abstract

PURPOSE:To obviate unequal adhesion and to prevent the generation of stresses by the unequal adhesion by providing an annular nonadhered part on the circumference of the central hole in the recording medium formed by sticking two sheets of optical disks to each other via an adhesive layer. CONSTITUTION:The optical information recording medium is formed by sticking two sheets of the optical disks 1, the recording films or reflecting films 2 of which are disposed on the inner side, via the adhesive layer 3 to each other and installing a center hub 4 to the central part on the outside surface of the optical disk 1. The annular nonadhered part 36 is provided around the sensor hole 7 to regulate the adhering range to a specified range. The unequal adhesion is eliminated in this way and the deterioration of appearance and the generation of the stresses occurring in the unequal adhesion are prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to an optical information recording medium having a closely bonded structure and a method for manufacturing the same.

[Prior Art] Conventionally, optical information recording media have been known that have a closely bonded structure in which two disk-shaped members including at least one optical disk are bonded together via an adhesive layer.

Conventionally, in this type of optical information recording medium, in order to prevent problems such as peeling, the most important thing has been firmly bonding two disk-shaped members together, as shown in Fig. 8. , an adhesive layer 54 is formed from the inner circumferential edge (center hole) 52 of the optical disk 51 to the outer circumferential edge 53, and the entire surface of the optical disk 51 is bonded (Japanese Patent Application Laid-Open No. 1983-1999).
6536).

[Problems to be Solved by the Invention] Incidentally, the optical information recording medium of the close-bonding structure has a center hole in the center and unevenness in a ring-shaped area excluding the innermost and outermost peripheries on one side. a step of manufacturing a transparent substrate on which a signal pattern is formed, a step of manufacturing an optical disk by forming a recording film or a reflective film on the signal pattern formation area of the transparent substrate, two disks manufactured as described above; The optical disc is manufactured through a step of concentrically bonding the optical disc and a disc-shaped protection plate with the recording film or reflective film on the inside and an adhesive layer interposed therebetween.

As a means of forming the adhesive layer, roll coating with hot melt adhesive is generally used because of its good workability. However, by forming a recording film or a reflective film, it is possible to The thickness of the signal pattern forming area is approximately 0.2 μm thicker than that of the recording area and the outer non-recording area, and a step is formed at the boundary between each area.
It is difficult to uniformly roll coat the entire surface of an optical disc with hot melt adhesive.

Therefore, uneven adhesion tends to occur at the boundaries between the areas, especially at the boundaries between the inner non-recording area, which is wider than the outer non-recording area, and the signal pattern forming area, which deteriorates the aesthetics of the product. Not only does the value decrease, but stress is generated due to uneven solidification and shrinkage of the adhesive, which tends to cause problems such as deformation of the transparent substrate and increased turbulence.

In addition, if a large amount of adhesive is applied to the surface of the optical disc in the adhesive layer forming process and the excess adhesive is pushed out from the inner and outer peripheries of the optical disc in the bonding process, even adhesiveness can be achieved. Although it is possible to do so, it requires a great deal of effort to remove the excess adhesive that has flowed out, so it cannot be used in practice.

The present invention has been made in order to solve the above-mentioned deficiencies of the prior art, and is an optical information recording medium that has no uneven adhesion, therefore has little vertical vibration during rotational driving, and has excellent optical properties and aesthetic appearance. It is an object of the present invention to provide a method for manufacturing such an optical information recording medium with high efficiency.

[Means to solve the problem]

In order to achieve the above object, the present invention provides an optical information recording medium having a close bonding structure in which two disk-shaped members including at least one optical disk are bonded together via an adhesive layer. A ring-shaped non-adhesive part was provided around the center hole.

Further, a step of producing a transparent substrate having a center hole in the center and having an uneven signal pattern formed in a ring-shaped area excluding the innermost and outermost peripheries on one side, the signal pattern of the transparent substrate; A step of manufacturing an optical disc by forming a recording film or a reflective film on a formation area, and depositing the recording film or reflective film on the two optical discs manufactured as described above, or the optical disc and the disc-shaped protection plate. In the method for manufacturing an optical information recording medium, which includes a step of concentrically bonding the transparent substrate on the inside and via an adhesive layer, when forming the transparent substrate, the periphery of the center hole on the inner periphery of the signal pattern forming area is A manufacturing method was adopted in which the region including the thin wall was formed thin, and the parts other than the thin wall portion were bonded together via an adhesive layer during assembly.

[Function] By providing a ring-shaped non-adhesive part around the center hole and regulating the adhesion range to a certain range, uneven adhesion at the chain part will be eliminated.
Deterioration of aesthetic appearance and generation of stress due to uneven adhesion can be prevented. Furthermore, since the generation of stress due to uneven adhesion can be prevented, vertical vibration during rotational driving and deterioration of optical characteristics due to increased retardation can be prevented.

In addition, regarding the method of manufacturing an optical information recording medium, when forming a transparent substrate, if a thin part is formed around the center hole, when two disc-shaped members are bonded together via an adhesive layer, the thin part Since no adhesive is attached to the parts, it is possible to fabricate optical information recording media with a tightly bonded structure with no uneven adhesion with high efficiency. [Example] Fig. 1 shows an optical information recording medium according to an example of the present invention. FIG. 2 is an enlarged cross-sectional view of a main part of this optical information recording medium, and FIG. 3 is a plan view of the optical disk constituting this optical information recording medium as seen from the recording film or reflective film side.

As shown in FIG. 1, in the optical information recording medium of this example, two optical discs 1 are bonded together with the recording film or reflective layer 2 on the inside and an adhesive layer 3 interposed therebetween, and the outer surface center of each optical disc 1 is A center hub 4 is attached to the portion.

The optical disc 1 has a signal pattern forming area 6 on a transparent substrate 5.
A recording layer or a reflective layer 3 is deposited thereon.

The transparent substrate 5 is made of, for example, glass or a transparent plastic material such as polycarbonate or polymethyl methacrylate, and is formed into a disk shape with a center hole 7 in the center as shown in FIG. A ring-shaped area excluding the outermost portion and the outermost portion is a signal pattern forming area 6. As schematically shown in the figure, in this signal pattern forming region 6, a spiral or concentric guide groove 8 is formed concentrically with the center hole 7, and along the guide groove 8, fine irregularities are formed. A pre-pit row 9 having a shape is preformatted. In this example, the prepit rows 9 are formed between adjacent guide grooves 8, but the prepit rows 9 can also be arranged on the guide grooves 8.

As shown in FIG. 2, on the inner periphery of the transparent substrate 5, a portion of the signal pattern forming area 6 is provided in a portion that is inner than the signal pattern forming area 6 and includes the periphery of the center hole 7. A thin-walled portion 10 is also formed, and a ring-shaped groove 11 is provided at the boundary between the signal pattern forming region 6 and the thin-walled portion 10 . The thickness dl of the thin portion 10 is
10 μm to 0 more than the thickness dl of the signal pattern forming region 6
．． It is formed to be 2mm thin.

In addition, if the thin part 10 is a part that is inner than the signal pattern forming area 6 and includes the periphery of the center hole 7,
Although it can be formed to any width, it is preferable that the area is equal to or slightly wider than the area clamped by the drive device when the optical information recording medium is mounted on the drive device, that is, the clamp area.

A recording film is provided for a write-once or rewritable optical disc 1, and a reflective film is provided for a read-only optical disc.

As the recording film, any known heat mode recording film can be used, but since a close bonding structure is adopted in which the recording films are bonded together via the adhesive layer 3, for example, a magneto-optical recording film or a phase change type recording film is used. Particularly suitable are recording films that repeatedly record information by reversibly changing the physical properties of the recording film, that is, those that can record information without changing the physical shape of the recording film. Note that although the recording layer 3 is shown as a single layer in the figure, a stack of a plurality of thin films made of different materials may also be used.

For example, in the case of a magneto-optical recording film, from the transparent substrate 5 side, a first enhancement film made of a dielectric material with a higher refractive index than the transparent substrate 5, a recording film made of a magneto-optical material, and the first
A second enhancement film made of the same dielectric material as the enhancement film, a reflective film made of a metal film with high reflectivity, and a protective film can be laminated in this order.

The adhesive layer 3 is uniformly formed in the range from the groove 11 of the transparent substrate 5 to the outer peripheral edge. As the adhesive constituting this adhesive layer 3, a hot melt adhesive, an epoxy resin, a photocurable adhesive, a thermosetting adhesive, an electron beam irradiation type adhesive, etc. can be used.

The center hub 4 is made of, for example, a metal material with excellent wear resistance or a magnetic metal material, and has a spindle hole 12 in the center thereof for mounting a turntable provided in a drive device. This center hub 4 is set concentrically with a guide groove 8 preformatted on the transparent substrate 5.

Hereinafter, a method for manufacturing the optical disc 1 according to the above embodiment will be explained.

FIG. 4 is a cross-sectional view of a main part of a mold used for filling and molding the transparent substrate 5, for example, injection molding or injection-compression molding.
22 is a fixed mold, 22 is a spool bush, 23 is a fixed cutter, 24 is a movable mold, 25 is a stamper, 26 is a presser on the inner circumference of the stamper, 27 is an eject ring, 28 is a movable cutter, 29 is an eject bin, and 30 is a stand bar. The outer ring 31 is a cavity.

Fixed mold 21. Spool bush 22, fixed cutter 2
The members on the fixed mold side consisting of 3 and the members on the movable mold side consisting of the stand bar 25, stamper inner periphery presser 26, eject ring 27, movable cutter 28, and eject bin 29 are arranged in parallel with each other with a cavity 31 in between. The thickness of the transparent substrate 5 is regulated by each of these members.

Further, the outer diameter of the transparent substrate 5 is regulated by the stamper outer circumference ring 30.

The stamper 25 is a thin plate-shaped mold in which an inverted pattern of the guide grooves 8 and pre-pit rows 9 to be transferred to the transparent substrate 5 is formed, and the stamper inner circumference presser 26 and the stamper outer circumference presser ring 30 It is attached to the movable mold 24.

Due to its structure, the upper surface of the stamper locking claw 26a provided around the outer periphery of the stamper inner periphery presser 26 is naturally attached to the stamper 25.
placed above the top surface of the

On the other hand, the top surface of the eject ring 27 is arranged at an intermediate position between the top surface of the stamper locking claw 26a and the top surface of the stamper 25. Stand bar 2 on the top of the eject ring 27
The amount of protrusion from the top surface of No. 5 is adjusted to 10 μm to 0.2 mm.

Therefore, from the spool bushing 22 to the cavity 31
By injecting molten resin into the cavity 31 and solidifying the resin inside the cavity 31, a ring-shaped groove 11 is formed in a portion of the stamper inner peripheral presser 26 corresponding to the stamper locking claw 26a, and corresponds to the eject ring 27. Thin wall part 1
A transparent substrate 5 on which 0 is formed can be manufactured.

Further, after solidifying the resin in the cavity 31, the movable cutter 28 is protruded, its tip is inserted into the fixed cutter 23, and the molten resin in the spool bushing 22 is cut, thereby forming the center hole 7. A transparent substrate 5 can be produced.

After taking out the transparent substrate 5 from the molding die, a recording film or a reflective film 2 is applied to the signal pattern forming area 6 using a film forming method such as sputtering or vacuum film forming, thereby producing an optical disc 1.

Next, an adhesive 33 is applied to the inner surface (the surface on which the recording film or reflective film 3 is formed) of the optical disc 1 manufactured as described above using a roll coater 32 shown in FIG.

In the figure, 34 is an adhesive application roller, and 35 is an adhesive supply port.

As shown in FIG. 5, there is a step difference of 10 μm = 0.2 mm between the thin-walled portion 10 and the thick-walled portion leading thereto, so the adhesive application roller 34 is brought into contact with the thick-walled portion. At this time, the adhesive 33 transferred to the roller 34 does not adhere to the thin portion 10. Therefore, when the two optical disks 1 coated with the adhesive 33 are bonded together, a non-adhesive portion 36 is formed in the thin portion 1o.

Moreover, since excess adhesive generated when two optical disks 1 are bonded together accumulates in the groove 11, uneven adhesion does not occur.

In the optical information recording medium of the above embodiment, a ring-shaped non-adhesive part 36 is provided around the center hole 7, and the adhesion range is restricted to a certain range, so uneven adhesion at the chain part is eliminated, and aesthetic deterioration and adhesion are prevented. Generation of stress due to unevenness can be prevented. Furthermore, since the generation of stress due to uneven adhesion can be prevented, vertical vibration during rotational driving and deterioration of optical characteristics due to increased retardation can be prevented.

Further, since the thin wall portion 10 is formed around the center hole 7 when forming the transparent substrate 5, the adhesive 33 does not stick to the thin wall portion 10 when roll coating the optical disc 1 with the adhesive 33. Therefore, an optical information recording medium having a tightly bonded structure with no uneven adhesion can be manufactured with high efficiency.

In the above embodiment, the adhesive layer 3 is formed of an adhesive such as a hot melt adhesive, but the adhesive layer 3 can also be formed of a double-sided adhesive film 41 as shown in FIG.

The double-sided adhesive film 41 is formed by providing adhesive layers 43 on both sides of a base film 42.

The base film 42 has a temperature of at least 60°C to 120°C.
It is formed from a material that undergoes no more than 10% thermal shrinkage when heated in the °C range. Specifically, a polymer compound containing a polyimide compound as a main component, a polymer compound containing polyphenylene oxide as a main component, a polymer compound containing polysulfone as a main component, etc. can be used.

Further, the adhesive layer 43 is made of hot melt adhesive (AC
VW-041-3 manufactured by I Japan Limited Co., Ltd.)
, or an adhesive with a curable substance added thereto. Curable substances include monomers, oligomers, photocurable acrylic monomers, photocurable oligomers, room temperature solid epoxy resins that are cured by a curing agent, electron beam curable monomers that are crosslinked by electron beam irradiation, or electron beam irradiation. An electron beam curable oligomer crosslinked by can be used.

Two optical discs 1 are attached using the double-sided adhesive film 41.
, prepare a double-sided adhesive film 41 cut into a ring shape with an inner and outer diameter approximately equal to that of the optical disc 1, and first apply the double-sided adhesive film 41 to the recording film or reflective film forming side of one optical disc 1. A method can be adopted in which the optical disk 1 and another optical disk 1 are adhered, and then this optical disk 1 and another optical disk 1 are arranged concentrically, and the surfaces on which the recording film or reflective film are formed are bonded together.

According to this method, the double-sided adhesive film 41 can be easily aligned with respect to the optical disc 1, and the manufacturing efficiency of the optical information recording medium can be improved.

Note that since the thin parts 10 of the transparent substrate 5 are not adhered to each other by the double-sided adhesive film 41, the same effects as in the previous embodiment can be achieved.

Further, in the above embodiment, a double-sided recording type optical information recording medium in which two optical discs 1 are bonded together was explained as an example, but as shown in FIG. The present invention can also be applied to a single-sided recording type optical information recording medium in which a protective plate 44 and a protective plate 44 are bonded together.

In addition, the present invention relates to the adhesive structure of the optical disc l and the protective plate 44, and includes the center hub 4 and the transparent substrate 5.
The shape, material, etc. can be arbitrarily designed regardless of the above embodiments.

[Effects of the Invention] As explained above, according to the present invention, a ring-shaped non-adhesive part is provided around the center hole and the adhesion range is restricted to a certain range, so uneven adhesion of the chain part is eliminated and the aesthetic appearance is improved. It is possible to prevent the deterioration of the optical properties due to the deterioration of the adhesive, the generation of stress due to uneven adhesion, and the increase in vertical runout tarpsion during rotational driving.

In addition, when forming the transparent substrate, a thin-walled part was formed around the center hole, making it difficult for an adhesive layer to form between the two disc-shaped members, making it possible to create an optical information recording medium with a tightly bonded structure with no uneven adhesion. It can be manufactured with high efficiency.

[Brief explanation of drawings]

Fig. 1 is a cross-sectional view of an optical information recording medium according to an embodiment of the present invention, Fig. 2 is a cross-sectional view of the main part thereof, Fig. 3 is a plan view of an optical disc, and Fig. 4 is a diagram of a transparent substrate molding die. Main part sectional view, 5th
6 is a sectional view of an optical information recording medium according to another embodiment of the present invention, and FIG. 7 is an illustration of an optical information recording medium according to still another embodiment of the present invention. Sectional view, No. 8
The figure is a sectional view of a conventional optical information recording medium. l... Optical disc, 2... Recording film or reflective film, 3... Adhesive layer, 4... Center hub, 5... Transparent Substrate, 6... Signal pattern forming area, 7... Center hole, 10.
... Thin wall part, 11 ... Concave groove, 36 ...
...Non-adhesive part.

Claims (8)

[Claims] (1) In an optical information recording medium with a close bonding structure in which two disk-shaped members including at least one optical disk are bonded together via an adhesive layer, a ring-shaped An optical information recording medium characterized by having a non-adhesive portion. (2) The optical information recording medium according to claim 1, wherein the clamp area of the optical disc is the non-adhesive portion. (3) In claim 1, the thickness of the non-adhesive portion of the transparent substrate constituting the optical disc is 10 μm to 0.2 mm greater than the thickness of the signal pattern forming area of the transparent substrate.
An optical information recording medium characterized by being formed with a thin wall. (4) The optical information recording medium according to claim 1, wherein a ring-shaped groove is formed on the outer periphery of the non-adhesive portion. (5) The optical information recording medium according to claim 1, wherein the adhesive layer is formed of a hot melt adhesive. (6) The optical information recording medium according to claim 1, wherein the adhesive layer is formed of a double-sided adhesive film. (7) A step of producing a transparent substrate having a center hole in the center and a concavo-convex signal pattern formed in a ring-shaped area excluding the innermost and outermost peripheries on one side, the signal of the transparent substrate A step of manufacturing an optical disc by forming a recording film or a reflective film on a pattern forming area, and depositing the two optical discs manufactured in the above manner, or the optical disc and the disc-shaped protective plate on the recording film or reflective film. In the method for manufacturing an optical information recording medium, the method includes the step of concentrically bonding the transparent substrate with the inner side and an adhesive layer interposed therebetween. 1. A method of manufacturing an optical information recording medium, characterized in that a region including a thin wall is formed thinly, and only a portion excluding the thin wall portion is bonded together via an adhesive layer during assembly. (8) A method for manufacturing an optical information recording medium according to claim 7, wherein the transparent substrate is formed by a filling molding method.