JP4333624B2 - Manufacturing method of optical recording medium - Google Patents

Description

The present invention relates to a recording of high density information, or for producing how an optical recording medium having information faces of two layers capable of reproducing.

  2. Description of the Related Art In general, optical recording media represented by optical discs such as DVDs that reproduce, record, and erase information using laser light are known as audio, image applications, and computer memories. In this optical recording medium recording / reproducing apparatus, the recording density of the optical disk is increased by increasing the aperture of the lens of the optical pickup, shortening the wavelength of the laser beam, and the like. In order to increase the density, it is necessary to suppress the lens aberration by shortening the distance between the objective lens of the optical pickup and the reflection film of the optical disk. That is, in order to suppress coma, it is necessary to reduce the thickness through which the laser light passes.

  As a high-density optical disc, for example, information consisting of pit rows or recording grooves is formed on the surface of a 1.1 mm thick substrate, which has a track pitch of 0.32 μm and a shortest recording pit of 0.16 μm, The signal system is a 2T (T: reference floc length) system on a disk having a diameter of 12 cm and has a recording capacity of 22 GB to 27 GB. On the information surface (recording surface) on the pit or recording groove on the surface of the substrate, a light transmission layer having a thickness of 90 μm to 110 μm is formed to protect this information surface and transmit laser light. Furthermore, in order to increase the recording density, it is necessary to increase the number of information surfaces, and an optical disc in which the information surfaces are stacked in two stages has been proposed.

  In order to make the information surface in two steps as described above, there is no particular problem because the information surface of the first step is formed directly on the surface of the substrate. Form a second-level information surface by applying a UV curable resin layer or the like on the underlying recording layer and transferring the grooves and pits to the surface using a transparent, for example, polycarbonate resin stamper. Was being considered. As such a disk structure, for example, optical recording media disclosed in Patent Document 1 and Patent Document 2 are known.

  In general, nickel metal is used as a stamper, but the reason for using a resin stamper made of a transparent polycarbonate resin or the like when forming the second stage information surface as described above is that the second stage information surface is formed. This is because the material to be formed is an ultraviolet curable resin layer, and the stamper needs to be transparent to ultraviolet rays in order to cure the resin layer.

International Publication Number WO99 / 00794 JP 2003-77187 A

By the way, in general, the ultraviolet curable resin has low adhesion to nickel metal, so that both can be easily separated, but the adhesion to polycarbonate resin is very high, and both are very difficult to separate. . Therefore, it becomes quite difficult to separate the resin stamper from the ultraviolet curable resin layer after the grooves and pits are transferred.
Therefore, in order to prevent the UV curable resin layer from adhering to the transparent resin stamper so that the two can be easily separated, a method of providing a release layer such as tetrafluoride or a transparent amorphous olefin resin is used. A method using a resin stamper is disclosed. In the above-mentioned Patent Document 2, a method of interposing a Teflon-based resin layer having a low adhesion to the ultraviolet curable resin is proposed.

However, when a special thin film such as a Teflon resin layer for facilitating separation from the UV curable resin layer is formed on the surface of the transparent resin stamper as described above, the transferability of grooves and pits is improved. In addition to the deterioration, the number of steps for forming a special thin film increases, so that there is a disadvantage that the running cost is increased and the product cost is increased accordingly.
The present invention has been devised to pay attention to the above problems and to effectively solve them. An object of the present invention is to provide an optical recording having an information surface of a two-layer structure that can be easily separated without forming a special thin film for facilitating separation from an ultraviolet curable resin layer on a transparent resin stamper. is to provide a manufacturing how media.

The related art of the present invention relates to a photo-curing property having a first intermediate layer and a second information surface on which grooves or pits are formed on a substrate having a first information surface on which grooves or pits are formed. In an optical recording medium in which a resin information layer, a second intermediate layer, and a light-transmitting protective layer are sequentially laminated, the information layer is an ultraviolet ray containing 8 to 14% of trimethylolpropane triacrylate. An optical recording medium characterized by being formed of a cured resin.

To claim 1 Ru engagement invention, on ZnS-SiO ₂ film-forming surface of the substrate having a first information surface grooves or pits are formed, a first intermediate layer, grooves or pits are formed a photocurable resin information layer having a second information surface is, and a light transparent protective layer at least sequentially stacked in a method of forming an optical recording medium, the hand when forming the information layer, said second information surface corresponding groove or pits polycarbonate resin formed on the surface of the stamper, ultraviolet from the stamper side contacting the UV-curable resin layer containing 8-14% trimethylolpropane Toriakurire over preparative The information layer is formed by irradiating and curing the optical recording medium.

According to the manufacturing method of the optical Symbol recording medium according to the present invention, it is possible to exhibit an excellent action and effect as follows.
Separation can be easily performed without forming a special thin film for facilitating separation from the ultraviolet curable resin layer on a transparent resin stamper.
Therefore, since it is not necessary to form a special thin film, it is possible not only to maintain high transferability of grooves and pits, but also to reduce the number of processes, thereby reducing running costs and product costs. Can be made.

Hereinafter will be described in detail based on an embodiment of a manufacturing how an optical recording medium according to the present invention in the accompanying drawings.
FIG. 1 is an enlarged sectional view showing a part of an optical recording medium according to the present invention, FIG. 2 is a process diagram showing a manufacturing process of the optical recording medium shown in FIG. 1, and FIG. 3 is another method for forming an information layer. FIG. 4 is a graph showing the relationship between the addition rate of trimethylol propantotriacrylate and the coating film remaining rate. Here, as an example of an optical recording medium, a recording type optical disc having two recording surfaces will be described as an example.

  As shown in FIG. 1, an optical disc D as an example of this optical recording medium has a disc-shaped substrate 2. Grooves (recording grooves) or pits 4 are formed on the surface of the substrate 2 to form the first information surface 2A. And on the 1st information surface 2A of this board | substrate 2, the 1st intermediate | middle layer 6, the information layer 8 which is the characteristics of this invention, the 2nd intermediate | middle layer 10, and the transparent protective layer 12 in this order It is formed by laminating sequentially. Then, a laser beam L for recording or reproduction is irradiated from the upper surface of the protective layer 12. Further, grooves (recording grooves) or pits 16 are formed on the surface (upper surface) of the information layer 8 to form the second information surface 8A.

  The substrate 2 is manufactured by injection molding using a thermoplastic resin such as polycarbonate resin mounted on an injection molding machine with a dedicated optical disk mold. A disk-shaped nickel disk called a stamper is mounted in the optical disk mold. On the surface of this nickel disk, an information surface comprising pit rows or recording grooves is formed as high-density information. For example, they have a track pitch of 0.32 μm, a shortest recording pit of 0.16 μm, and a diameter. The signal system is a 2T system on a 12 cm disc and has a recording capacity of 22 GB to 27 GB. The pits and the like are transferred by such an injection molding process, and the substrate 2 having the first information surface 2A formed on the surface is manufactured.

The first intermediate layer 6 is formed by sequentially laminating a reflective film such as Al, a recording film such as GeSbTe, and a dielectric film such as ZnS—SiO ₂ .
The information layer 8 is formed of an ultraviolet curable resin containing 8 to 14% of trimethylol propantotriacrylate, and the second information surface 8A is formed on the surface of the information layer 8 by a light-transmitting resin stamper as will be described later. As a result, the separation from the stamper is improved.
The second intermediate layer 10 is formed by sequentially stacking a recording film such as GeSbTe and a dielectric film of ZnS—SiO ₂ , for example. For example, a polycarbonate resin film or the like is used for the protective layer 12.

Next, a specific manufacturing process of the optical disc D will be described with reference to FIG.
First, FIG. 2A shows a substrate 2 having a first information surface 2A with grooves and pits 4 formed on the surface, and the substrate 2 is formed of polycarbonate resin or the like. Then, as shown in FIG. 2B, a reflective film such as an Al alloy is formed on the substrate 2 by sputtering or vapor deposition to a thickness of 10 to 100 nm, a GeSbTe-based recording film is 100 to 130 nm, and a ZnS—SiO ₂ dielectric film. Are sequentially formed to form the first intermediate layer 6.

Next, as shown in FIG. 2 (C), 8 to 14% of trimethylolpropane triacrylate is added to a light-transmitting resin stamper 20 made of polycarbonate resin or the like in which grooves and pits 16 are formed. An ultraviolet curable resin layer 22 is applied by a spin coater, and the ultraviolet curable resin layer 22 is bonded to the first intermediate layer 6 in a vacuum, and an ultraviolet ray is applied from the transparent stamper 20 side as shown in FIG. Curing by UV irradiation.
In this case, instead of the process of FIG. 2C, as shown in FIG. 3, an ultraviolet curable resin layer 22 is applied on the first intermediate layer 6 by a spin coater, and the ultraviolet curable resin is applied in a vacuum. A transparent stamper 20 may be pressed onto the layer 22 (see FIG. 2D).

  As described above, the information layer 8 is formed by curing the ultraviolet curable resin layer 22 by irradiation with ultraviolet UV, and after the curing, the transparent stamper 20 is separated or peeled off. As a result, as shown in FIG. 2E, the grooves or pits 16 of the transparent stamper 20 are transferred to form the second information surface 8 A on the upper surface of the information layer 8. In this case, as described above, the information layer 8 is formed of an ultraviolet curable resin containing 8 to 14% of trimethylolpropane triacrylate (manufactured by Kyoeisha Chemical Co., Ltd.). The peelability is good and not only can be easily separated, but also the transferability can be kept high. In addition, the adhesiveness (adhesiveness) to the first intermediate layer 6 that is the base can be kept high.

Next, as shown in FIG. 2F, a GeSbTe-based recording film is formed in a thickness of 100 to 130 nm, and a ZnS—SiO ₂ dielectric film is sequentially formed in a thickness of 15 to 30 nm to form a second intermediate layer 10. Then, a transparent protective layer 12 made of an ultraviolet curable resin or a polycarbonate resin film having a thickness of 100 μm is formed on the second intermediate layer 10 to complete the optical disc D as shown in FIG. . Here, both of the first and second intermediate layers 6 and 10 have a function as a recording layer, and become a recording type optical disc having a two-layer recording surface.

As described above, according to the present invention, a special thin film for facilitating separation from the ultraviolet curable resin layer can be easily separated without forming a transparent resin stamper.
Therefore, since it is not necessary to form a special thin film, it is possible not only to maintain high transferability of grooves and pits, but also to reduce the number of processes, thereby reducing running costs and product costs. Can be made.

Next, since the separation property (peelability) of the transparent stamper 20 with respect to the ultraviolet curable resin layer 22 (information layer 8) was examined and evaluated, the evaluation result will be described.
FIG. 4 is a graph showing the relationship between the addition rate of trimethylol propantotriacrylate and the coating film remaining rate.

In this evaluation experiment, an Al alloy reflective film, a GeSbTe-based recording film, and a ZnS-SiO ₂ derivative film are formed on a substrate 2 such as a polycarbonate resin having grooves and pits by sputtering or vapor deposition as described above. Were sequentially laminated to form a first intermediate layer 6. On the first intermediate layer 6, trimethylolpropane triacrylate as a whole is mixed with 0, 2, 4, 6 with respect to a mixed solution of 5 g of epoxy acrylate, 65 g of isobornyl acrylate, and 30 g of polyisobornyl acrylate. , 8, 10, 12, 14, 16, 18, 20, 22, 25, 30%, and further, UV curable resin 22 to which 3% of photoinitiator is further added is spin coater (600 rpm). ), And was irradiated with ultraviolet rays (365 nm) at 1000 mj / cm ² (integrated light amount) to be cured. Similarly, an ultraviolet curable resin to which trimethylolpropane triacrylate was added was applied to a polycarbonate resin substrate and cured.

Similarly, a polycarbonate resin substrate was regarded as the stamper 20, and an ultraviolet curable resin layer formed by adding trimethylolpropane triacrylate was applied to the stamper 20 and cured as described above.
The adhesion (coating film residual ratio) of each ultraviolet curable resin cured as described above was measured by a cross-cut method (cross cut cell tape test). The result is shown in FIG. From FIG. 4, when the addition ratio of trimethylolpropane triacrylate increases, the adhesion to the SiO ₂ —ZnS film (first intermediate layer 6), which is a dielectric film, deteriorates, and similarly the adhesion to the polycarbonate resin (stamper). Becomes worse. Ideally, it is optimal that the ultraviolet curable resin layer (information layer 8) adheres to the dielectric film and does not adhere to the polycarbonate resin (stamper 20).

  Here, when the addition ratio of trimethylolpropane triacrylate is 6%, the residual ratio in the dielectric film is 100% and the residual ratio in the polycarbonate resin is 18%. When the addition ratio of trimethylolpropane triacrylate is 8%, the residual ratio in the dielectric film is 100% and the residual ratio in the polycarbonate resin is 5%. When the addition ratio of trimethylolpropane triacrylate is 10% or 12%, the remaining ratio in the dielectric film is 100% and the remaining ratio in the polycarbonate resin is 0%. When the addition ratio of trimethylolpropane triacrylate is 14%, the residual ratio in the dielectric film is 95% and the residual ratio in the polycarbonate resin is 0%. When the addition ratio of trimethylolpropane triacrylate is 16%, the residual ratio in the dielectric film is 87% and the residual ratio in the polycarbonate resin is 0%. Therefore, the addition ratio of trimethylolpropane triacrylate is 8 to 14% so that the groove or pit can be transferred to the resin layer without adhering to the stamper made of polycarbonate resin and adhering to the dielectric film. Was confirmed.

In the above embodiment, the recording type double-layered optical disk has been described as an example. However, the present invention is not limited to this, and the present invention can also be applied to a read-only type double-layered optical disk. In the case of a read-only optical disc, the first intermediate layer 6 includes a total reflection type reflection film, and the second intermediate layer 10 includes a translucent reflection film. The present invention can also be applied to a two-layer optical disc in which one of the two layers is a recording type and the other is a reproduction type.
Furthermore, the present invention is mainly intended to enable a high-density two-layer structure in an optical disc, but can also be applied to a structure in which a fine structure such as an optical card or a micromachine is transferred.

1 is an enlarged cross-sectional view showing a part of an optical recording medium according to the present invention. FIG. 2 is a process diagram showing a manufacturing process of the optical recording medium shown in FIG. 1. It is explanatory drawing which shows the other method at the time of forming an information layer. It is a graph which shows the relationship between the addition rate of a trimethylol propanto triacrylate, and a coating film residual rate.

Explanation of symbols

2 ... substrate, 2A ... first information surface, 4 ... pit, 6 ... first intermediate layer, 8 ... information layer, 8A ... second information surface, 10 ... second intermediate layer, 12 ... protective layer, 16: Pit, 20: Stamper, 22: UV curable resin, D: Optical disc (optical recording medium).

Claims (1)

On the ZnS-SiO ₂ film-forming surface of the substrate having a first information surface grooves or pits are formed,
A first intermediate layer;
An information layer made of a photocurable resin having a second information surface in which grooves or pits are formed;
In a method of forming an optical recording medium by sequentially laminating a light-transmitting protective layer,
Hand in forming the information layer, the second corresponding to the information surface grooves or pits polycarbonate resin formed on the surface of the stamper, ultraviolet curing resin layer containing 8-14% trimethylolpropane Toriakurire over preparative A method for producing an optical recording medium, characterized in that the information layer is formed by contacting the substrate and irradiating and curing ultraviolet rays from the stamper side.

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