JP2751458B2 - Optical recording medium - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an optical recording medium such as an optical disk (compact disk), a video disk, an optical card, etc., and in particular, to an improvement in preservability and throughput of a reflective film layer. The present invention relates to an optical recording medium capable of achieving the following.

[Prior Art] Optical recording has advantages over magnetic recording in that a recording medium and a head are not in contact with each other and high-density recording is possible. As this optical recording medium, a read-only medium, an additionally writable medium, and an erasable / rewritable medium are known. As the read-only optical recording medium according to the present invention, an optical disk ( Compact discs), optical video discs, optical cards and the like have been put to practical use.

By the way, as an optical recording medium of this type, recently, a signal uneven pattern or pregroove is transferred to a base sheet (for example, PMMA, PC, PVC, etc.) by hot pressing, and a reflection film layer is formed on the transfer surface. An inert gas (for example, nitrogen) is formed in the pits and pregrooves for the purpose of forming a base film as a substrate on the reflective film layer with an adhesive, and further preventing corrosion due to oxidation of the reflective film layer. Gas-sealed optical recording media in which a gas or the like is sealed has been proposed.

[Problems to be Solved by the Invention] However, this kind of conventional gas-filled optical recording medium has the following various problems.

(A) Since the reflection film layer is exposed to the air during storage, deterioration due to oxidation is likely to occur. Even if it is wound up, it is not suitable for long-term storage.

(B) The base sheet usually has a thickness of about 1.2 mm,
In a heat press, the throughput is hardly increased due to heat radiation and the like. Further, even if a UV resin is used as the material of the base sheet, the throughput is hardly increased.

(C) When transferring pits or pregrooves to a base sheet by a winding method, the base sheet has a thickness of 1.2 mm, and therefore needs to be wound on a roll having a large diameter. Nevertheless, an increase in birefringence cannot be avoided.

(D) In order to prevent corrosion due to oxidation of the reflective film layer, if an inert gas is sealed in the pits or pre-grooves, the cost will increase accordingly.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and has good storage stability of a reflection film layer, can improve throughput, and can be rolled up and has a birefringence of a base sheet. It is an object of the present invention to provide an optical recording medium which is inexpensive without increasing the cost.

[Means for Solving the Problems] In order to achieve the above object, an optical recording medium of the present invention is provided with a reflective film layer provided on a substrate and a reflective film layer provided on the reflective film layer. A molding layer made of a resin on which an uneven pattern or a pre-groove is formed; an adhesive layer provided on the molding layer; and a transparent base sheet provided on the adhesive layer. The signal is read based on the difference in the refractive index of the resin of the molding layer.

Here, it is particularly preferable to use any one of a disk shape, a card shape, and a sheet shape, for example, as described in claim 2.

Further, it is preferable that the substrate is a polyester resin, for example.

Further, the reflective film layer is preferably made of a metal such as aluminum or copper, for example.

On the other hand, it is preferable that the molding layer is a urethane resin, for example, as described in claim 5.

The base sheet is preferably a polyester resin, for example, as described in claim 6.

Furthermore, the depth of the pits and pregrooves
For example, as described in claim 7, the thickness is preferably 0.2 to 0.5 μm.

[Operation] Therefore, in the optical recording medium of the present invention, the presence of the molding layer on the reflective film layer allows the reflective film layer to be stored for a long period of time without deterioration due to oxidation of the reflective film layer. Becomes possible. In addition, by forming a concavo-convex pattern or a pre-groove of a signal on the reflective film layer by hot pressing, it is possible to wind up and increase the throughput. Further, it is possible to prevent the birefringence of the base sheet from increasing. Furthermore, since it is not necessary to fill an inert gas in the pits or the pregrooves in order to prevent corrosion due to oxidation of the reflection film layer, the cost can be reduced accordingly.

[Example] The optical recording medium of the present invention forms a signal concavo-convex pattern or a pre-groove by hot pressing on a molding layer of a laminated plate in which a reflective film layer and a molding layer are sequentially laminated on a substrate. A transparent substrate sheet is laminated on the layer with an adhesive, and a signal is read based on a difference between the air pits and the refractive index of the resin of the molded layer.

Hereinafter, an embodiment of the present invention based on the above concept will be described in detail with reference to the drawings.

FIG. 1 is a cross-sectional view showing an example of the overall configuration of an optical disc which is an optical recording medium according to the present invention. As shown in FIG. 1, the optical disc of the present embodiment comprises a windable substrate 1, a reflective film layer 2, a molding layer 3, an adhesive layer 4, and a transparent base sheet 5. doing.

Here, the material of the substrate 1 is generally a resin having heat resistance, for example, polyester resin, polyamide resin, polyimide resin, polycarbonate resin, polymethyl methacrylate resin, methyl perten resin, ionomer resin, polyether sulfone resin, vinyl chloride resin. , Polystyrene resin, cellulosic resin or the like, or a laminate thereof. Then, from the characteristics such as surface smoothness and heat resistance, the thickness is 10 μm to 500 μm (preferably 30 μm
It is optimal to use a polyester resin of about 150 μm). In this embodiment, a polyester resin having a thickness of 50 μm is used.

Further, as the reflection film layer 2, aluminum, gold, copper,
Vacuum evaporation, sputtering, metal such as tin and nickel
The thickness is set to a thickness (about 100 to 10,000) at which a specified reflectance can be obtained by a method such as ion plating. In this example, a reflective film layer 2 having a thickness of 0.1 μm made of aluminum is provided.

On the other hand, as the molding layer 3, in consideration of the balance with the substrate 1, a resin, for example, a urethane resin or PVC formed on the reflective film layer 2 is applied and dried by a method such as roll coating or blade coating. Form. And the film thickness is 0.2 μm to 1.0 μm (preferably 0.3 μm to 0.5 μm).
μm). In this example, a molded layer 3 of 0.4 μm in thickness made of urethane resin is provided. Also, the surface of the stamper, that is, the signal master is superimposed on the forming layer 3 by the press machine, and after heating and pressing of about 90 ° to 160 ° and then cooling, the forming layer 3 is formed by embossing. A signal such as a pit or a concavo-convex pattern such as a pregroove is formed. In this case, any of a flat press, a circular press, or a rotary press can be used,
In the present example, the roll embossing can be performed with particularly high productivity by using the rotary method. The depth of the pits and pre-grooves is set to 0.2 to 0.5 μm (the phase difference of the light beam between the portion where the pits and the pre-groove is and the portion where the pits and the pre-groove are not set to be π / 2 by a double pulse). Is preferred). In this example, pits having a depth of 0.35 μm are transferred by hot pressing using a stamper.

As the adhesive used for the adhesive layer 4, a general adhesive such as a urethane-based adhesive, an epoxy-based adhesive, or an acrylic-based adhesive can be used. In this example, an acrylic adhesive is used.

Further, as a material of the base sheet 5, a resin having transparency and small birefringence is generally used in consideration of transmittance, birefringence, and the like. For example, acrylic resins such as polycarbonate and polymethyl methacrylate are used. Resins, cellulose resins such as polyester, polyamide, vinyl chloride, and polystyrene, and the like, or a laminate thereof can be used. In this example, a polyester resin is used.

It is desirable that the molding layer 3 and the substrate 1 are combined such that only the molding layer 3 is softened during hot pressing and the substrate 1 is not softened. For example, a urethane resin is used for the molding layer 3 and a polycarbonate resin is used for the substrate 1. . In FIG. 1, the reflective film layer 2 is flat without irregularities. However, even if the reflective film layer 2 has no irregularities, the signal of the air pit / the resin of the molding layer 3 has a difference in refractive index. Reading is enabled.

In the optical disk configured as described above, since the molding layer 3 exists on the reflective film layer 2, the reflective film layer 2 does not deteriorate due to oxidation,
Can be stored for a long time. In addition, since signals such as pits and uneven patterns such as pregrooves are formed on the reflective film layer 2 by hot pressing, winding can be performed and throughput can be significantly increased. Further, even if the pit is formed by winding, it can be wound on a small drum as compared with the conventional method, and the increase in the birefringence of the base sheet 5 can be prevented. Furthermore, in order to prevent corrosion due to oxidation of the reflective film layer 2, it is not necessary to fill an inert gas for corrosion prevention in the pits or pregrooves as in the conventional case, so that the cost is reduced accordingly. be able to.

As described above, the optical disc of the present embodiment includes a windable substrate 1 and a reflective film layer 2 provided on the substrate 1.
A molding layer 3 provided on the reflective film layer 2 and having a signal uneven pattern or pregroove formed by hot pressing; an adhesive layer 4 provided on the molding layer 3; The transparent base sheet 5 is provided, and a signal is read based on a difference in refractive index between the air pits and the resin of the molding layer 3.

Therefore, the following various functions and effects can be obtained.

(A) Since the molding layer 3 is present on the reflective film layer 2, the reflective film layer 2 does not deteriorate due to oxidation, and the reflective film layer 2 can be stored for a long period of time.

(B) Since signals such as pits and uneven patterns such as pregrooves are formed on the reflective film layer 2 by hot pressing,
Winding is possible and throughput can be increased.

(C) It is possible to prevent the birefringence of the base sheet 5 from increasing.

(D) In order to prevent corrosion due to oxidation of the reflection film layer 2,
Since there is no need to fill an inert gas in the pits or pre-grooves as in the related art, the cost can be reduced accordingly. An optical disc can be obtained.

In the above embodiment, the case where the present invention is applied to an optical disk has been described. However, the present invention is not limited to this, and the present invention is similarly applied to an optical video disk, an optical card, and other sheet-shaped optical recording media. To obtain the same effect.

[Effects of the Invention] As described above, according to the present invention, a reflective film layer provided on a substrate and a resin provided on the reflective film layer and having a signal concavo-convex pattern or a pre-groove formed by hot pressing A molding layer, and an adhesive layer provided on the molding layer,
The transparent base sheet provided on the adhesive layer is provided, and the signal is read based on the difference between the refractive index of the resin of the air pit and the resin of the molding layer. Therefore, the storage stability of the reflective film layer is good. In addition, it is possible to provide an optical recording medium which can be wound up, can be wound up, does not increase the birefringence of the base sheet, and is inexpensive at the same time.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment in which the present invention is applied to an optical disk. DESCRIPTION OF SYMBOLS 1 ... board | substrate, 2 ... reflective film layer, 3 ... molding layer, 4 ... adhesive layer, 5 ... base material sheet.

Claims (7)

(57) [Claims] A reflective layer provided on a substrate; a molded layer made of a resin provided on the reflective layer and having a concavo-convex pattern or a pre-groove of signals formed by hot pressing; And a transparent base sheet provided on the adhesive layer, wherein a signal is read based on a difference in refractive index between the resin of the air pit and the molding layer. Optical recording medium. 2. The optical recording medium according to claim 1, wherein the substrate is one of a disk, a card, and a sheet. 3. The optical recording medium according to claim 1, wherein said substrate is a polyester resin. 4. The optical recording medium according to claim 1, wherein said reflection film layer is made of a metal such as aluminum or copper. 5. The optical recording medium according to claim 1, wherein said molding layer is a urethane resin. 6. The optical recording medium according to claim 1, wherein said base sheet is a polyester resin. 7. The optical recording medium according to claim 1, wherein the depth of said pits and pre-grooves is set to 0.2 to 0.5 μm.