JP5772022B2 - Optical information recording medium - Google Patents

Description

  The present invention relates to an optical information recording medium. Specifically, the present invention relates to an optical information recording medium including three or more information signal layers.

  As the density of optical information recording media increases, for example, high-density optical discs and the like that realize a markedly larger capacity than conventional CDs (Compact Discs) and DVDs (Digital Versatile Discs) are known.

  In a high density optical disc, an information signal layer for recording and / or reproducing information signals is formed on one main surface of a disc substrate. On the information signal layer, for example, a light transmission layer and a protective layer are formed by spin coating. At the time of recording / reproducing an information signal, the information signal layer is irradiated with laser light through the light transmission layer, and the information signal is recorded or reproduced by the laser light.

  In the above-described high-density optical disc, a light transmission layer is formed only on the information reading surface side on which laser light is incident. Therefore, a high-density optical disc has an asymmetric structure in the thickness direction of the disc, and is more likely to warp than a DVD or the like.

  In order to deal with the problem of warping of a high-density optical disk, for example, in Patent Document 1 below, the elastic modulus at 25 ° C. and the elastic modulus at −20 ° C. are within a predetermined range, and the glass transition temperature is −20 ° C. to An optical information recording medium having a light transmission layer at 0 ° C. has been proposed.

JP 2009-271970 A

  An object of the present technology is to provide an optical information recording medium in which warpage is suppressed.

The present technology provides a substrate, three or more information signal layers formed on the substrate, two or more intermediate layers interposed between the three or more information signal layers, and a position farthest from the substrate. A light transmission layer formed on an information signal layer, the storage elastic modulus of the light transmission layer at −5 ° C. is approximately 1200 MPa , and the storage elastic modulus of each of the two or more intermediate layers at −5 ° C. Is an optical information recording medium having a storage elastic modulus of 2850 MPa or more and 2950 MPa or less and a storage elastic modulus of each of the two or more intermediate layers at 25 ° C. of 1850 MPa or more and 2440 MPa or less.

  The present technology controls the storage elastic modulus of the light transmission layer at −5 ° C. and the storage elastic modulus of the intermediate layer at −5 ° C. and 25 ° C. for an optical information recording medium having three or more information signal layers. Thereby, the change of the curvature of an optical information recording medium is suppressed. Even if the environment in which the optical information recording medium is used is extremely low (−5 ° C.), the change in warpage is small, so that the optical information recording medium can be recorded and reproduced stably even at such a low temperature.

  According to the present technology, warping of the optical information recording medium at a low temperature can be suppressed.

FIG. 1A is a schematic cross-sectional view illustrating a configuration example of an optical information recording medium according to an embodiment of the present technology. FIG. 1B is a schematic diagram illustrating a configuration example of each information signal layer illustrated in FIG. 1A. FIG. 2 is a graph showing the storage elastic modulus with respect to the environmental temperature of samples Ra to Rc. FIG. 3A is a schematic cross-sectional view for explaining the layer configuration of the optical disks for evaluation of samples Q-1 to Q-3. FIG. 3B is a schematic cross-sectional view for explaining the layer configuration of the optical disks for evaluation of samples T-1 to T-3. FIG. 4A is a graph showing the difference Δβ = β _L −β _H between the warp angle under the environment of −5 ° C. and the warp angle under the environment of 25 ° C. for samples Q-1 to Q-3. FIG. 4B is a graph showing the difference Δβ = β _L −β _H between the warp angle under the environment of −5 ° C. and the warp angle under the environment of 25 ° C. for samples T-1 to T-3. 5A is a graph showing the relationship between the storage elastic modulus of Samples Q-1 to Q-3 in a temperature environment of −5 ° C. and Δβ of Samples Q-1 to Q-3 shown in FIG. 4A. is there. FIG. 5B is a graph showing the relationship between the storage elastic modulus of Samples Q-1 to Q-3 in a temperature environment of 25 ° C. and Δβ of Samples Q-1 to Q-3 shown in FIG. 4A. . FIG. 6A is a graph showing the relationship between the storage elastic modulus of Samples T-1 to T-3 in a temperature environment of −5 ° C. and Δβ of Samples T-1 to T-3 shown in FIG. 4B. is there. 6B is a graph showing the relationship between the storage elastic modulus of Samples T-1 to T-3 in a temperature environment of 25 ° C. and Δβ of Samples T-1 to T-3 shown in FIG. 4B. .

Embodiments of the present technology will be described below with reference to the drawings.
[Configuration of optical information recording medium]
FIG. 1A is a schematic cross-sectional view illustrating a configuration example of an optical information recording medium according to an embodiment of the present technology. The optical information recording medium 10 is, for example, a write-once type optical information recording medium, and as shown in FIG. 1A, an information signal layer L0, an intermediate layer S1, an information signal layer L1, an intermediate layer S2, an information signal layer L2, The intermediate layer S3, the information signal layer L3, and the light transmission layer 2 that is a protective layer (cover layer) are laminated on one main surface of the substrate 1 in this order. If necessary, a hard coat layer 3 may be further provided on the surface of the light transmission layer 2 side. If necessary, a barrier layer 4 may be further provided on the surface on the substrate 1 side.

  In the optical information recording medium 10 according to this embodiment, information signals are recorded or reproduced by irradiating the information signal layers L0 to L3 with laser light from the surface C on the light transmitting layer 2 side. For example, laser light having a wavelength in the range of 400 nm or more and 410 nm or less is condensed by an objective lens having a numerical aperture in the range of 0.84 or more and 0.86 or less, and each information signal layer L0 is formed from the light transmission layer 2 side. The information signal is recorded or reproduced by irradiating .about.L3. An example of such an optical information recording medium 10 is BD-R (Blu-ray Disc Recordable Format). Hereinafter, the surface C on which the laser light for recording information signals on the information signal layers L0 to L3 is referred to as a light irradiation surface C. In the following description, the information signal layers are referred to as information signal layers L0, L1, L2,... In order from the substrate 1 side toward the information reading surface side where the laser light is incident. The intermediate layers are referred to as intermediate layers S1, S2,... In order from the optical disc substrate 1 side toward the information reading surface side where the laser light is incident.

  Hereinafter, the substrate 1, the information signal layers L0 to L3, the intermediate layers S1 to S3, the light transmission layer 2, the hard coat layer 3, and the barrier layer 4 constituting the optical information recording medium 10 will be sequentially described.

(substrate)
The substrate 1 has, for example, an annular shape in which an opening (hereinafter referred to as a center hole) is formed in the center. One principal surface of the substrate 1 is, for example, an uneven surface, and the information signal layer L0 is formed on the uneven surface. Hereinafter, of the concavo-convex surface, the concave portion is referred to as in-groove Gin, and the convex portion is referred to as on-groove Gon.

  Examples of the shapes of the in-groove Gin and the on-groove Gon include various shapes such as a spiral shape and a concentric circle shape. The in-groove Gin and / or the on-groove Gon are wobbled (meandered) to add address information, for example.

  The diameter of the substrate 1 is selected to be 120 mm, for example. The thickness of the substrate 1 is selected in consideration of rigidity, preferably from 0.3 mm to 1.3 mm, more preferably from 0.6 mm to 1.3 mm, for example, 1.1 mm. It is. The diameter (diameter) of the center hole is selected to be 15 mm, for example.

  The diameter (diameter) of the substrate 1 is selected to be 120 mm, for example. The thickness of the substrate 1 is selected in consideration of rigidity, and is preferably 0.3 mm or more and 1.3 mm or less, more preferably 0.6 mm or more and 1.3 mm or less, for example, 1.1 mm. The diameter (diameter) of the center hole is selected to be 15 mm, for example.

  As a material of the substrate 1, for example, a plastic material or glass can be used. From the viewpoint of cost, it is preferable to use a plastic material. As the plastic material, for example, a polycarbonate resin, a polyolefin resin, an acrylic resin, or the like can be used.

(Information signal layer)
FIG. 1B is a schematic diagram illustrating a configuration example of each information signal layer illustrated in FIG. 1A. As shown in FIG. 1B, the information signal layers L0 to L3 include, for example, the inorganic recording layer 11, the first protective layer 12 provided adjacent to one main surface of the inorganic recording layer 11, and the inorganic recording layer 11. And a second protective layer 13 provided adjacent to the other main surface. With such a configuration, the durability of the inorganic recording layer 11 can be improved.

  The inorganic recording layer 11 of at least one of the information signal layers L1 to L3 other than the information signal layer L0 that is the farthest from the light irradiation surface C is a ternary element of W oxide, Pd oxide, and Cu oxide. It is preferable to contain a system oxide as a main component. This is because excellent transmission characteristics can be realized while satisfying the characteristics required for the information signal layer of the optical information recording medium. The same applies to the case where there are five or more information signal layers.

    At least one inorganic recording layer 11 among the information signal layers L1 to L3 other than the information signal layer L0 which is the farthest from the light irradiation surface C is obtained by adding Zn oxide to the ternary oxide described above. It is preferable to contain a quaternary oxide as a main component. By adding Zn oxide, the total amount other than Zn oxide can be reduced while maintaining excellent transmission characteristics while satisfying the characteristics required for the information signal layer of the optical information recording medium. That is, by adding Zn oxide, the ratio of expensive Pd oxide can be reduced, and cost reduction can be realized. The same applies to the case where there are five or more information signal layers.

  As the first protective layer 12 and the second protective layer 13, a dielectric layer or a transparent conductive layer is preferably used, and a dielectric layer is used as one of the first protective layer and the second dielectric layer 13, while the other It is also possible to use a transparent conductive layer. Since the dielectric layer or the transparent conductive layer functions as an oxygen barrier layer, the durability of the inorganic recording layer 11 can be improved. In addition, by suppressing the escape of oxygen in the inorganic recording layer 11, changes in the film quality of the recording film (mainly detected as a decrease in reflectance) can be suppressed, and the necessary film quality for the inorganic recording layer 11 is ensured. be able to. Furthermore, the recording characteristics can be improved by providing a dielectric layer or a transparent conductive layer. This is because the thermal diffusion of the laser light incident on the dielectric layer or the transparent conductive layer is optimally controlled, and the bubbles in the recording portion become too large, or the decomposition of the Pd oxide proceeds so much that the bubbles collapse. This is considered to be because the shape of bubbles during recording can be optimized.

Examples of the material of the first protective layer 12 and the second protective layer 13 include oxides, nitrides, sulfides, carbides, fluorides, or mixtures thereof. As the material of the first protective layer 12 and the second protective layer 13, the same or different materials can be used. As the oxide, for example, an oxide of one or more elements selected from the group consisting of In, Zn, Sn, Al, Si, Ge, Ti, Ga, Ta, Nb, Hf, Zr, Cr, Bi, and Mg Is mentioned. As the nitride, for example, a nitride of one or more elements selected from the group consisting of In, Sn, Ge, Cr, Si, Al, Nb, Mo, Ti, Nb, Mo, Ti, W, Ta, and Zn Preferably, a nitride of one or more elements selected from the group consisting of Si, Ge, and Ti is used. Examples of the sulfide include Zn sulfide. Examples of the carbide include carbides of one or more elements selected from the group consisting of In, Sn, Ge, Cr, Si, Al, Ti, Zr, Ta, and W, preferably a group consisting of Si, Ti, and W And carbides of one or more elements selected from the above. Examples of the fluoride include fluorides of one or more elements selected from the group consisting of Si, Al, Mg, Ca, and La. Examples of the mixture include ZnS—SiO ₂ , SiO ₂ —In ₂ O ₃ —ZrO ₂ (SIZ), SiO ₂ —Cr ₂ O ₃ —ZrO ₂ (SCZ), In ₂ O ₃ —SnO ₂ (ITO). ), In ₂ O ₃ —CeO ₂ (ICO), In ₂ O ₃ —Ga ₂ O ₃ (IGO), In ₂ O ₃ —Ga ₂ O ₃ —ZnO (IGZO), Sn ₂ O ₃ —Ta ₂ O ₅ (TTO), TiO ₂ —SiO _{2 and the} like.

(Middle layer)
The intermediate layers S1 to S3 are layers that separate the information signal layers L0 to L3, respectively. The surface on the light transmission layer 2 side of the intermediate layers S <b> 1 to S <b> 3 is an uneven surface composed of an in-groove Gin and an on-groove Gon, like the substrate 1.

  The storage elastic modulus of each of the intermediate layers S1 to S3 is preferably 2860 MPa or more and 2950 MPa or less in a temperature environment of −5 ° C., and 1850 MPa or more and 2440 MPa or less in a temperature environment of 25 ° C. By setting each storage elastic modulus of the intermediate layer within the above range, even when the environmental temperature slowly changes from room temperature to −5 ° C., the change in warpage can be suppressed to about 0.2 [deg] or less. . Each storage elastic modulus of the intermediate layer is more preferably 2880 MPa or more and 2920 MPa or less in a temperature environment of −5 ° C., and 2000 MPa or more and 2280 MPa or less in a temperature environment of 25 ° C. By setting each storage elastic modulus of the intermediate layer within the above range, even when the environmental temperature slowly changes from room temperature to −5 ° C., the change in warpage can be suppressed to about 0.1 [deg] or less. .

  From the viewpoint of forming three or more information signal layers, the total thickness of the intermediate layers is preferably 40 μm or more and 49.5 μm or less. By using three or more information signal layers and making the total thickness of the intermediate layers within a predetermined range, for example, using an objective lens having a high NA (numerical aperture) of about 0.85, High density recording can be realized.

  As a material of the intermediate layers S1 to S3, for example, a resin material having transparency can be used. Examples of such a resin material include an ultraviolet curable resin composition. For example, the intermediate layers S1 to S3 can be formed by curing the ultraviolet curable resin composition. As the ultraviolet curable resin composition, for example, a plastic material such as an acrylic resin can be used.

"Ultraviolet curable resin composition"
The ultraviolet curable resin composition contains at least an oligomer component and a photopolymerization initiator component. Further, it may contain at least one of a bifunctional or higher monomer component and a monofunctional monomer component.

  For example, the ultraviolet curable resin composition is an oligomer whose viscosity at 25 ° C. in a liquid state before the curing reaction is 300 mPa · s to 3000 mPa · s, and the glass transition temperature of the single cured product is −50 ° C. to 15 ° C. or lower. A component and a photopolymerization initiator component. Moreover, this ultraviolet curable resin composition may contain at least any one of the bifunctional or more functional monomer component and monofunctional monomer component whose glass transition point temperature of a single-cured material is -40 degreeC-90 degreeC or less.

  The ultraviolet curable resin composition preferably has a storage elastic modulus at −5 ° C. of 2860 MPa to 2950 MPa and a storage elastic modulus at 25 ° C. of 1850 MPa to 2440 MPa after the curing reaction. It is set. The ultraviolet curable resin composition is more preferably set such that the storage elastic modulus at −5 ° C. is 2880 MPa or more and 2920 MPa or less and the storage elastic modulus at 25 ° C. is set in the range of 2000 MPa or more and 2280 MPa or less. It is. The ultraviolet curable resin composition has a glass transition temperature of -20 ° C or higher and 20 ° C or lower after the curing reaction.

"Oligomer component"
As the oligomer component, for example, a (meth) acrylate oligomer can be used. Here, (meth) acrylate means either acrylate or methacrylate. As the (meth) acrylate oligomer, for example, urethane (meth) acrylate, epoxy (meth) acrylate, or the like having a glass transition point temperature of a single cured product of −50 ° C. to 15 ° C. can be used. Examples of commercially available urethane (meth) acrylate products include UV-6100B (manufactured by Nippon Synthetic Chemical Co., Ltd.), EB230, EB8405 (manufactured by Daicel Cytec Co., Ltd.), and CN9004 (manufactured by Sartomer Japan Co., Ltd.). It is done. As an example of a commercially available epoxy (meth) acrylate, EB3500 (manufactured by Daicel Cytec Co., Ltd.) can be mentioned. The (meth) acrylate oligomer has, for example, 2 to 4 (meth) acryloyl groups in the molecule (repeating unit). Here, the (meth) acryloyl group means either an acryloyl group or a methacryloyl group. The number average molecular weight of the (meth) acrylate oligomer is preferably 500 to 10,000. (Meth) acrylate oligomers may be used alone or in combination of two or more.

"Photopolymerization initiator component"
As the photopolymerization initiator component, a photopolymerization initiator in which the long wavelength side absorption edge of the ultraviolet-visible absorption spectrum of 0.01% acetonitrile solution is less than λ = 405 nm can be suitably used. Examples of the photopolymerization initiator include 1-hydroxy-cyclohexyl-phenyl ketone, 2-hydroxy-2-methyl-1-phenyl-propan-1-one, 2-methyl-1 [4-methylthio] phenyl] -2- And morpholinopropan-1-one. One example of a commercially available 1-hydroxy-cyclohexyl-phenyl-ketone is Irgacure 184 (manufactured by Ciba Japan Co., Ltd.). An example of a commercially available product of 2-hydroxy-2-methyl-1-phenyl-propan-1-one is Darocur 1173 (manufactured by Ciba Japan Co., Ltd.). An example of a commercially available product of 2-hydroxy-2-methyl-1-phenyl-propan-1-one is Darocur 1173 (manufactured by Ciba Japan Co., Ltd.). An example of a commercially available product of 2-methyl-1 [4-methylthio] phenyl-2-morpholinopropan-1-one is Irgacure 907 (manufactured by Ciba Japan Co., Ltd.).

"Bifunctional or higher monomer component"
As the bifunctional or higher monomer component, a bifunctional or higher functional (meth) acrylate monomer can be used. This bifunctional or higher functional (meth) acrylate monomer has a glass transition temperature of a single cured product of −40 ° C. to 90 ° C., and an aliphatic residue or alicyclic residue in the main chain structure or side chain structure. And having an aromatic residue.

  Bifunctional or higher functional (meth) acrylate monomers include ethoxylated hexanediol diacrylate, caprolactone-modified hydroxypivalic acid neopentyl glycol diacrylate, ethoxylated trimethylolpropane triacrylate, propoxylated trimethylolpropane triacrylate, caprolactone-modified dipenta Examples include erythritol hexaacrylate. Two or more (meth) acrylate monomers having two or more functions can be used in combination.

  HX-620 (manufactured by Nippon Kayaku Co., Ltd.) is an example of a commercially available product of caprolactone-modified hydroxypivalic acid neopentyl glycol diacrylate. Examples of commercially available products of ethoxylated trimethylolpropane triacrylate include CD561 and SR9035 (both manufactured by Sartomer Japan, Inc.). One example of a commercially available propoxylated trimethylolpropane triacrylate is SR492 (manufactured by Sartomer Japan, Inc.). An example of a commercial product of caprolactone-modified dipentaerythritol hexaacrylate is DPCA-120 (manufactured by Nippon Kayaku Co., Ltd.).

"Monofunctional monomer component"
A monofunctional (meth) acrylate monomer can be used as the monofunctional monomer component. This monofunctional (meth) acrylate monomer has a glass transition temperature of a single cured product of −50 ° C. to 50 ° C., and the main chain structure or side chain structure has an aliphatic residue, alicyclic residue, aromatic It has a family residue. Examples of the monofunctional (meth) acrylate monomer include 2-phenoxyethyl acrylate and tetrahydrofurfuryl acrylate. A monofunctional (meth) acrylate monomer may be used by 1 type and may use 2 or more types together.

  As an example of a commercial product of 2-phenoxyethyl acrylate, light acrylate PO-A (manufactured by Kyoei Chemical Co., Ltd.) can be mentioned. As an example of a commercially available product of tetrahydrofurfuryl acrylate, SR285 (manufactured by Sartomer Japan Co., Ltd.) can be mentioned.

  The blending amount of the oligomer component is, for example, 10 parts by weight to 80 parts by weight when the total amount of the ultraviolet curable resin composition is 100 parts by weight. The compounding quantity of a photoinitiator component shall be 0.5 mass part-10 mass parts, for example. When blending a bifunctional or higher monomer component and a monofunctional monomer component, the blending amounts are as follows. The blending amount of the bifunctional or higher monomer component is 20 parts by mass to 60 parts by mass. The compounding quantity of a monofunctional monomer component shall be 5 mass parts-30 mass parts.

(Light transmission layer)
The light transmission layer 2 is a resin layer formed by curing a photosensitive resin such as an ultraviolet curable resin. Or you may make it comprise the light transmissive layer 2 from the light transmissive sheet | seat which has an annular shape, and the contact bonding layer for bonding this light transmissive sheet | seat with respect to the board | substrate 1. FIG. The light-transmitting sheet is preferably made of a material having a low absorption ability with respect to laser light used for recording and reproduction, specifically, a material having a transmittance of 90% or more. As a material for the light transmissive sheet, for example, a polycarbonate resin material, a polyolefin-based resin (for example, ZEONEX (registered trademark)), or the like can be used. As the material for the adhesive layer, for example, an ultraviolet curable resin, a pressure sensitive adhesive (PSA), or the like can be used. The storage elastic modulus at −5 ° C. of the light transmission layer 2 is set in the range of 1500 MPa or less, and more preferably in the range of 20 MPa or more and 1500 MPa or less. Thereby, the warp of the optical information recording medium 10 at a low temperature of about −5 ° C. can be reduced.

  The thickness of the light transmission layer 2 is preferably selected from the range of 10 μm or more and 177 μm or less. For example, when the information signal layer has three or four layers, it is selected in the range of approximately 50 μm to 60 μm. High density recording can be realized by combining such a thin light transmission layer 2 and an objective lens having a high NA of, for example, about 0.85.

  Examples of the material of the light transmissive layer 2 include an ultraviolet curable resin composition. For example, the light transmissive layer 2 can be formed by curing the ultraviolet curable resin composition. As the ultraviolet curable resin composition, for example, a plastic material such as an acrylic resin can be used.

"Ultraviolet curable resin composition"
The ultraviolet curable resin composition contains at least an oligomer component and a photopolymerization initiator component. Further, it may contain at least one of a bifunctional or higher monomer component and a monofunctional monomer component.

  For example, the ultraviolet curable resin composition is an oligomer whose viscosity at 25 ° C. in a liquid state before the curing reaction is 300 mPa · s to 3000 mPa · s, and the glass transition temperature of the single cured product is −50 ° C. to 15 ° C. or lower. A component and a photopolymerization initiator component. Moreover, this ultraviolet curable resin composition may contain at least any one of the bifunctional or more functional monomer component and monofunctional monomer component whose glass transition point temperature of a single-cured material is -40 degreeC-90 degreeC or less.

  The ultraviolet curable resin composition has a storage elastic modulus at −5 ° C. within a range of 1500 MPa or less after the curing reaction. The ultraviolet curable resin composition is more preferably set within a range of 20 MPa to 1500 MPa. The ultraviolet curable resin composition has a glass transition temperature of -20 ° C or higher and 20 ° C or lower after the curing reaction.

"Oligomer component"
As the oligomer component, for example, a (meth) acrylate oligomer can be used. Here, (meth) acrylate means either acrylate or methacrylate. As the (meth) acrylate oligomer, for example, urethane (meth) acrylate, epoxy (meth) acrylate, or the like having a glass transition point temperature of a single cured product of −50 ° C. to 15 ° C. can be used. Examples of commercially available urethane (meth) acrylate products include UV-6100B (manufactured by Nippon Synthetic Chemical Co., Ltd.), EB230, EB8405 (manufactured by Daicel Cytec Co., Ltd.), and CN9004 (manufactured by Sartomer Japan Co., Ltd.). It is done. As an example of a commercially available epoxy (meth) acrylate, EB3500 (manufactured by Daicel Cytec Co., Ltd.) can be mentioned. The (meth) acrylate oligomer has, for example, 2 to 4 (meth) acryloyl groups in the molecule (repeating unit). Here, the (meth) acryloyl group means either an acryloyl group or a methacryloyl group. The number average molecular weight of the (meth) acrylate oligomer is preferably 500 to 10,000. (Meth) acrylate oligomers may be used alone or in combination of two or more.

"Photopolymerization initiator component"
As the photopolymerization initiator component, a photopolymerization initiator in which the long wavelength side absorption edge of the ultraviolet-visible absorption spectrum of 0.01% acetonitrile solution is less than λ = 405 nm can be suitably used. Examples of the photopolymerization initiator include 1-hydroxy-cyclohexyl-phenyl ketone, 2-hydroxy-2-methyl-1-phenyl-propan-1-one, 2-methyl-1 [4-methylthio] phenyl] -2- And morpholinopropan-1-one. One example of a commercially available 1-hydroxy-cyclohexyl-phenyl-ketone is Irgacure 184 (manufactured by Ciba Japan Co., Ltd.). An example of a commercially available product of 2-hydroxy-2-methyl-1-phenyl-propan-1-one is Darocur 1173 (manufactured by Ciba Japan Co., Ltd.). An example of a commercially available product of 2-hydroxy-2-methyl-1-phenyl-propan-1-one is Darocur 1173 (manufactured by Ciba Japan Co., Ltd.). An example of a commercially available product of 2-methyl-1 [4-methylthio] phenyl-2-morpholinopropan-1-one is Irgacure 907 (manufactured by Ciba Japan Co., Ltd.).

"Bifunctional or higher monomer component"
As the bifunctional or higher monomer component, a bifunctional or higher functional (meth) acrylate monomer can be used. This bifunctional or higher functional (meth) acrylate monomer has a glass transition temperature of a single cured product of −40 ° C. to 90 ° C., and an aliphatic residue or alicyclic residue in the main chain structure or side chain structure. And having an aromatic residue.

  Bifunctional or higher functional (meth) acrylate monomers include ethoxylated hexanediol diacrylate, caprolactone-modified hydroxypivalic acid neopentyl glycol diacrylate, ethoxylated trimethylolpropane triacrylate, propoxylated trimethylolpropane triacrylate, caprolactone-modified dipenta Examples include erythritol hexaacrylate. Two or more (meth) acrylate monomers having two or more functions can be used in combination.

  HX-620 (manufactured by Nippon Kayaku Co., Ltd.) is an example of a commercially available product of caprolactone-modified hydroxypivalic acid neopentyl glycol diacrylate. Examples of commercially available products of ethoxylated trimethylolpropane triacrylate include CD561 and SR9035 (both manufactured by Sartomer Japan, Inc.). One example of a commercially available propoxylated trimethylolpropane triacrylate is SR492 (manufactured by Sartomer Japan, Inc.). An example of a commercial product of caprolactone-modified dipentaerythritol hexaacrylate is DPCA-120 (manufactured by Nippon Kayaku Co., Ltd.).

"Monofunctional monomer component"
A monofunctional (meth) acrylate monomer can be used as the monofunctional monomer component. This monofunctional (meth) acrylate monomer has a glass transition temperature of a single cured product of −50 ° C. to 50 ° C., and the main chain structure or side chain structure has an aliphatic residue, alicyclic residue, aromatic It has a family residue. Examples of the monofunctional (meth) acrylate monomer include 2-phenoxyethyl acrylate and tetrahydrofurfuryl acrylate. A monofunctional (meth) acrylate monomer may be used by 1 type and may use 2 or more types together.

  As an example of a commercial product of 2-phenoxyethyl acrylate, light acrylate PO-A (manufactured by Kyoei Chemical Co., Ltd.) can be mentioned. As an example of a commercially available product of tetrahydrofurfuryl acrylate, SR285 (manufactured by Sartomer Japan Co., Ltd.) can be mentioned.

  The blending amount of the oligomer component is, for example, 10 parts by weight to 80 parts by weight when the total amount of the ultraviolet curable resin composition is 100 parts by weight. The compounding quantity of a photoinitiator component shall be 0.5 mass part-10 mass parts, for example. When blending a bifunctional or higher monomer component and a monofunctional monomer component, the blending amounts are as follows. The blending amount of the bifunctional or higher monomer component is 20 parts by mass to 60 parts by mass. The compounding quantity of a monofunctional monomer component shall be 5 mass parts-30 mass parts.

(Hard coat layer)
The hard coat layer 3 is for imparting scratch resistance and the like to the light irradiation surface C. As a material of the hard coat layer 3, for example, an acrylic resin, a silicone resin, a fluorine resin, an organic-inorganic hybrid resin, or the like can be used.

(Barrier layer)
The barrier layer 4 suppresses degassing (moisture release) from the back surface of the substrate 1 in the film forming process. The barrier layer 4 also functions as a moisture-proof layer that suppresses moisture absorption on the back surface of the substrate 1. The material constituting the barrier layer 4 is not particularly limited as long as it can suppress degassing (moisture release) from the back surface of the substrate 1. A low dielectric can be used. Examples of such a dielectric, for example, can be used SiN, SiO _2, TiN, AlN, etc. ZnS-SiO _2. The thickness of the barrier layer 4 is preferably set to 5 nm or more and 40 nm or less. When the thickness is less than 5 nm, the barrier function for suppressing degassing from the back surface of the substrate tends to decrease. On the other hand, when the thickness exceeds 40 nm, the barrier function for suppressing degassing is hardly different from the case of a film thickness of less than that, and the productivity tends to be lowered. The moisture permeability of the barrier layer 4 is preferably 5 × 10 ⁻⁵ g / cm ² · day or less.

[Method of manufacturing optical information recording medium]
Next, an example of a method for manufacturing an optical information recording medium according to an embodiment of the present technology will be described. In the following, an example of the manufacturing method will be described by taking an example in which the information signal layers are four information signal layers L0 to L3.

(Substrate molding process)
First, the board | substrate 1 with which the uneven surface was formed in one main surface is shape | molded. As a method for molding the substrate 1, for example, an injection molding (injection) method, a photopolymer method (2P method: Photo Polymerization), or the like can be used.

(Information signal layer formation process)
Next, the information signal layer L0 is formed by sequentially laminating the first protective layer 12, the inorganic recording layer 11, and the second protective layer 13 on the substrate 1 by, for example, sputtering.
Below, the formation process of the 1st protective layer 12, the inorganic recording layer 11, and the 2nd protective layer 13 is demonstrated concretely.

(First protective layer deposition step)
First, the substrate 1 is transported into a vacuum chamber provided with a target containing a dielectric material or a transparent conductive material as a main component, and the inside of the vacuum chamber is evacuated to a predetermined pressure. Thereafter, the target is sputtered while introducing a process gas such as Ar gas or O ₂ gas into the vacuum chamber, and the first protective layer 12 is formed on the substrate 1. As the sputtering method, for example, a radio frequency (RF) sputtering method or a direct current (DC) sputtering method can be used, and a direct current sputtering method is particularly preferable. This is because the direct current sputtering method has a higher film formation rate than the high frequency sputtering method, and thus can improve productivity.

(Inorganic recording layer deposition process)
Next, the substrate 1 is transferred into a vacuum chamber provided with a target for forming an inorganic recording layer, and the inside of the vacuum chamber is evacuated to a predetermined pressure. Here, the target for forming the inorganic recording layer is a ternary oxide of W oxide, Pd oxide, and Cu oxide, or 4 of W oxide, Pd oxide, Cu oxide, and Zn oxide. Contains ternary oxide as the main component. Thereafter, the target is sputtered while introducing a process gas such as Ar gas or O ₂ gas into the vacuum chamber, and the inorganic recording layer 12 is formed on the first protective layer 11.

(Second protective layer deposition step)
Next, the substrate 1 is transferred into a vacuum chamber provided with a target containing a dielectric material or a transparent conductive material as a main component, and the inside of the vacuum chamber is evacuated to a predetermined pressure. Thereafter, the target is sputtered while introducing a process gas such as Ar gas or O ₂ gas into the vacuum chamber, and the second protective layer 13 is formed on the inorganic recording layer 12. As the sputtering method, for example, a radio frequency (RF) sputtering method or a direct current (DC) sputtering method can be used, and a direct current sputtering method is particularly preferable. This is because the direct current sputtering method has a higher film formation rate than the high frequency sputtering method, and thus can improve productivity.
Thus, the information signal layer L0 is formed on the substrate 1.

(Intermediate layer formation process)
Next, the compounding quantity of an above-described component is adjusted suitably as a material of an intermediate | middle layer, and the ultraviolet curable resin composition for intermediate | middle layer formation is prepared. At this time, the storage elastic moduli of each of the intermediate layers S1 to S3 are 2860 MPa to 2950 MPa in a temperature environment of −5 ° C., and 1850 MPa to 2440 MPa in a temperature environment of 25 ° C. Do. More preferably, preparation is performed such that the pressure is 2880 MPa or more and 2920 MPa or less in a temperature environment of −5 ° C., and 2000 MPa or more and 2280 MPa or less in a temperature environment of 25 ° C. Next, the prepared ultraviolet curable resin is uniformly applied onto the information signal layer L0 by, for example, spin coating. Thereafter, the concave / convex pattern of the stamper is pressed against the ultraviolet curable resin uniformly applied on the information signal layer L0, and the ultraviolet curable resin is irradiated with ultraviolet rays to be cured, and then the stamper is peeled off. As a result, the uneven pattern of the stamper is transferred to the ultraviolet curable resin, and an intermediate layer S1 provided with, for example, in-groove Gin and on-groove Gon is formed on the information signal layer L0.

(Information signal layer and intermediate layer formation process)
Next, the information signal layer L1, the intermediate layer S1, the information signal layer L2, the intermediate layer S3, and the information signal layer L3 are formed on the intermediate layer S1 in the same manner as in the process of forming the information signal layer L0 and the intermediate layer S1. They are laminated on the intermediate layer S1 in this order. At this time, the film thickness and composition of the first protective layer 12, the inorganic recording layer 11, and the second protective layer 13 constituting the information signal layers L0 to L3 are adjusted by appropriately adjusting the film forming conditions and the target composition. You may make it adjust suitably. Moreover, you may make it adjust the thickness of intermediate | middle layer S2-S3 suitably by adjusting the conditions of a spin coat method suitably.

(Light transmission layer forming process)
Next, the compounding amount of the above-described components as a material for the light transmission layer is appropriately adjusted to prepare an ultraviolet curable resin composition for forming the light transmission layer. At this time, it prepares so that the storage elastic modulus in -5 degreeC of the light transmissive layer 2 may be 1500 Mpa or less. Next, a photosensitive resin such as a prepared ultraviolet curable resin (UV resin) is spin-coated on the information signal layer L3 by, for example, spin coating, and then the photosensitive resin is irradiated with light such as ultraviolet rays to be cured. . Thereby, the light transmission layer 2 is formed on the information signal layer L3.
Through the above steps, a desired optical information recording medium is obtained.

  Hereinafter, the present technology will be specifically described by way of examples with reference to FIGS. 2 to 6, but the present technology is not limited only to these examples. The information signal layers L0 to L3 are configured to be able to record and / or reproduce information signals. The configuration is appropriately selected depending on, for example, whether the desired optical information recording medium is a reproduction-only type, a write-once type, or a rewritable type. Hereinafter, a write-once optical information recording medium will be specifically described as an example. Hereinafter, a quaternary oxide of tungsten oxide, palladium oxide, copper oxide, and zinc oxide is referred to as “WZCPO”.

  First, UV curable resin compositions of samples Ra to Rc were prepared, and samples Q-1 to Q-3 and samples T-1 to T- using the UV curable resin compositions of samples Ra to Rc as materials for the intermediate layer were used. 3 was prepared.

<Sample Ra>
The compounding quantity of the following components was adjusted suitably and the ultraviolet-ray cured resin composition of sample Ra was prepared.
Oligomer component urethane (meth) acrylate (trade name: UV6100B, manufactured by Nippon Synthetic Chemical Co., Ltd.)
Photopolymerization initiator component (trade name: Irgacure 184, manufactured by Ciba Japan Co., Ltd.)
Bifunctional or higher monomer component propoxylated trimethylolpropane triacrylate (trade name: SR9035, manufactured by Sartomer Japan, Inc.)
Caprolactone-modified dipentaerythritol hexaacrylate (trade name: DPCA-120 manufactured by Nippon Kayaku Co., Ltd.)

<Sample Rc>
In sample Ra, by appropriately changing the blending amount of the oligomer component, photopolymerization initiator component, bifunctional or higher monomer component, the amount of each component, and, if necessary, the above-mentioned monofunctional monomer component A UV curable resin composition of sample Rc was prepared.

<Sample Rb>
The ultraviolet curable resin composition of sample Rb was prepared so that each component which comprises the ultraviolet curable resin composition of sample Ra and sample Rc might be 1: 1 by weight ratio.

  FIG. 2 is a graph showing the storage elastic modulus with respect to the environmental temperature of samples Ra to Rc. In FIG. 2, the storage elastic moduli of the samples Ra, Rb and Rc under the respective temperatures are indicated by points Pa, Pb and Pc, respectively.

The storage elastic modulus shown in FIG. 2 was measured as follows. First, an ultraviolet curable resin composition was sandwiched between PET films and coated so that the film thickness after curing was 100 μm, and then a metal halide lamp (UVL-4000M3-N1, manufactured by Ushio Electric Co., Ltd., lamp output 120 W / cm) was used. Curing was performed at 500 mJ / cm ² . The storage elastic modulus of this cured film under a temperature environment of −20 ° C. to 100 ° C. was measured with a viscoelastic spectrometer (DMS6100 manufactured by Seiko Instruments Inc.). The viscoelastic spectrometer applies 1 Hz periodic strain (tension) to the sample, and measures viscoelasticity by the time delay of the stress generated from the sample in response to this strain.

  Optical disks for evaluation of samples Q-1 to Q-3 and samples T-1 to T-3 were prepared using the ultraviolet resin compositions of samples Ra to Rc as materials for the intermediate layer.

<Sample Q-1>
First, a transparent substrate 1 (polycarbonate disk) having a diameter of 120 mm (φ120) and a thickness of 1.1 mm was formed from a raw material pellet of polycarbonate resin by an injection molding method.

Next, the information signal layer L0 was formed on one main surface of the substrate 1 with the following layer structure by sputtering.
(Substrate /) Transparent conductive layer / Inorganic recording layer / Transparent conductive layer Material: (Polycarbonate /) ITO / WZCPO / ITO
Layer thickness: (1.1mm /) 8nm / 32nm / 8nm

  Next, the ultraviolet resin composition of sample Ra was applied onto the substrate on which the information signal layer L0 was formed by spin coating. Then, the ultraviolet ray resin composition of sample Ra was hardened by irradiating with ultraviolet rays to form an intermediate layer S1 having a thickness of 15.5 μm. Note that, from the viewpoint of signal amount stabilization such as recording / reproduction, the thickness of the intermediate layer S1 is preferably in the range of 14.5 μm to 16.5 μm.

Next, the information signal layer L1 was formed on one main surface of the intermediate layer S1 with the following layer configuration by sputtering.
Transparent conductive layer / inorganic recording layer / transparent conductive layer material: ITO / WZCPO / ITO
Layer thickness: 7nm / 40nm / 8nm

  Next, the ultraviolet resin composition of sample Ra was applied onto one main surface of the information signal layer L1 by spin coating. Then, the ultraviolet ray resin composition of sample Ra was hardened by irradiating with ultraviolet rays to form an intermediate layer S2 having a thickness of 19.5 μm. Note that, from the viewpoint of signal amount stabilization such as recording / reproduction, the thickness of the intermediate layer S2 is preferably in the range of 18.5 μm to 20.5 μm.

Next, the information signal layer L2 was formed on one main surface of the intermediate layer S2 with the following layer structure by sputtering.
Transparent conductive layer / inorganic recording layer / dielectric layer material: ITO / WZCPO / SIZ
Layer thickness: 10nm / 35nm / 24nm

  Next, the ultraviolet resin composition of sample Ra was applied on one main surface of the information signal layer L2 by spin coating. Then, the ultraviolet ray resin composition of sample Ra was hardened by irradiating with ultraviolet rays to form an intermediate layer S3 having a thickness of 11.5 μm. From the viewpoint of stabilizing the signal amount such as recording / reproduction, the thickness of the intermediate layer S3 is preferably in the range of 10.5 μm to 12.5 μm.

Next, the information signal layer L3 was formed on one main surface of the intermediate layer S3 with the following layer configuration by sputtering.
Dielectric layer / inorganic recording layer / dielectric layer material: SIZ / WZCPO / SIZ
Layer thickness: 10nm / 35nm / 31nm

Next, the compounding quantity of the following components was adjusted suitably and the ultraviolet curable resin composition for light transmissive layer formation was prepared.
Oligomer component urethane (meth) acrylate (trade name: UV6100B, manufactured by Nippon Synthetic Chemical Co., Ltd.)
Photopolymerization initiator component (trade name: Irgacure 184, manufactured by Ciba Japan Co., Ltd.)
Bifunctional or higher monomer component propoxylated trimethylolpropane triacrylate (trade name: SR9035, manufactured by Sartomer Japan, Inc.)
Caprolactone-modified dipentaerythritol hexaacrylate (trade name: DPCA-120 manufactured by Nippon Kayaku Co., Ltd.)

  In addition, when the storage elastic modulus of the ultraviolet curable resin composition for forming a light transmission layer at −5 ° C. was measured with a viscoelastic spectrometer in the same manner as in the case of the ultraviolet resin compositions of samples Ra to Rc, it was 1200 MPa. there were.

  Next, the above-described ultraviolet curable resin composition for forming a light transmission layer was applied onto one main surface of the information signal layer L3 by spin coating. Thereafter, the ultraviolet curable resin composition for forming a light transmissive layer is cured by irradiating with ultraviolet rays, and the light transmissive layer 2 having a thickness of 53.5 μm is formed to obtain an optical disk for evaluation of sample Q-1. It was.

<Sample Q-2>
An optical disk for evaluation of sample Q-2 was obtained in the same manner as sample Q-1, except that the ultraviolet curable resin composition of sample Rb was used as the material for the intermediate layers S1, S2, and S3.

<Sample Q-3>
An optical disk for evaluation of sample Q-3 was obtained in the same manner as sample Q-1, except that the ultraviolet curable resin composition of sample Rc was used as the material for the intermediate layers S1, S2 and S3.

<Sample T-1>
First, a transparent substrate 1 (polycarbonate disk) having a diameter of 120 mm (φ120) and a thickness of 1.1 mm was formed from a raw material pellet of polycarbonate resin by an injection molding method.

Next, the information signal layer L0 was formed on one main surface of the substrate 1 with the following layer structure by sputtering.
(Substrate /) Transparent conductive layer / Inorganic recording layer / Transparent conductive layer Material: (Polycarbonate /) ITO / WZCPO / ITO
Layer thickness: (1.1mm /) 8nm / 32nm / 8nm

  Next, the ultraviolet resin composition of sample Ra was applied onto the substrate on which the information signal layer L0 was formed by spin coating. Then, the ultraviolet ray resin composition of sample Ra was hardened by irradiating with ultraviolet rays to form an intermediate layer S1 having a thickness of 25 μm. Note that, from the viewpoint of signal amount stabilization such as recording and reproduction, the thickness of the intermediate layer S1 is preferably in the range of 24 um to 26 um.

Next, the information signal layer L1 was formed on one main surface of the intermediate layer S1 with the following layer configuration by sputtering.
Transparent conductive layer / inorganic recording layer / transparent conductive layer material: ITO / WZCPO / ITO
Layer thickness: 7nm / 40nm / 8nm

  Next, the ultraviolet resin composition of sample Ra was applied onto one main surface of the information signal layer L1 by spin coating. Then, the ultraviolet ray resin composition of sample Ra was cured by irradiating with ultraviolet rays to form an intermediate layer S2 having a thickness of 18 μm. Note that, from the viewpoint of signal amount stabilization such as recording / reproduction, the thickness of the intermediate layer S2 is preferably within a range of 17 μm or more and 19 μm or less.

Next, the information signal layer L2 was formed on one main surface of the intermediate layer S2 with the following layer structure by sputtering.
Transparent conductive layer / inorganic recording layer / dielectric layer material: ITO / WZCPO / SIZ
Layer thickness: 10nm / 35nm / 24nm

  Next, in the same manner as in the case of sample Q-1, the above-described ultraviolet curable resin composition for forming a light transmission layer was applied on one main surface of the information signal layer L2 by spin coating. Thereafter, the ultraviolet curable resin composition for forming a light transmissive layer was cured by irradiating with ultraviolet rays, and the light transmissive layer 2 having a thickness of 57 μm was formed to obtain an optical disk for evaluation of sample T-1.

<Sample T-2>
An optical disk for evaluation of sample T-2 was obtained in the same manner as sample T-1, except that the ultraviolet curable resin composition of sample Rb was used as the material for the intermediate layers S1 and S2.

<Sample T-3>
An optical disk for evaluation of sample T-3 was obtained in the same manner as sample T-1, except that the ultraviolet curable resin composition of sample Rc was used as the material for the intermediate layers S1 and S2.

  FIG. 3A schematically shows the layer structure of the optical disks for evaluation of samples Q-1 to Q-3. FIG. 3B schematically shows the layer structure of the optical disks for evaluation of samples T-1 to T-3.

  Using the optical disks for evaluation of Samples Q-1 to Q-3 and Samples T-1 to T-3, for evaluating the storage elastic modulus of the ultraviolet resin composition used as the material of the intermediate layers S1 to S3 and changes in the environmental temperature The relationship between the amount of change in the warp angle (β angle) of the optical disk was examined by the following procedure.

First, the warp angle β _H of each sample in an environment of 25 ° C. was measured. Next, each sample was allowed to stand for 24 hours or more in an environment of −5 ° C., and then the warp angle β _L of each sample was measured. Here, the warp angle β _H or β _L is the warp angle R-skew [deg] at a point of 58 mm along the radial direction from the center of the disk. The measurement was performed using an Argus blue manufactured by Schwab.

Next, for each sample, the difference Δβ = β _L −β _H between the warp angle under the environment of −5 ° C. and the warp angle under the environment of 25 ° C. was determined. FIG. 4A shows Δβ of samples Q-1 to Q-3, and FIG. 4B shows Δβ of samples T-1 to T-3.

  Next, for each sample, from the measurement results shown in FIG. 2, the storage elastic modulus of the intermediate layer under a certain temperature environment is read, and the relationship between the storage elastic modulus of the intermediate layer under a certain temperature environment and Δβ is respectively determined. Asked.

  5A is a graph showing the relationship between the storage elastic modulus of Samples Q-1 to Q-3 in a temperature environment of −5 ° C. and Δβ of Samples Q-1 to Q-3 shown in FIG. 4A. is there. The graph shown in FIG. 5A is a graph with the storage elastic modulus in a temperature environment of −5 ° C. as the horizontal axis and Δβ as the vertical axis. For example, for sample Q-1, the storage elastic modulus in the temperature environment of −5 ° C. read from FIG. 2 is 2840 [MPa], the warp angle in the temperature environment of −5 ° C., and the temperature environment of 25 ° C. The difference Δβ from the warp angle is −0.32 [deg]. Therefore, for sample Q-1, the point (2980, -0.32) will be plotted. The same procedure is followed for sample Q-2 and sample Q-3.

  Next, an approximate straight line was determined by the method of least squares from the set of storage elastic modulus and Δβ plotted for samples Q-1 to Q-3. The approximate straight line is shown as a straight line A1 in FIG. 5A.

  Next, the storage elastic modulus in a temperature environment of −5 ° C. corresponding to a certain Δβ was obtained from the intersection of the straight line of Δβ = (constant) [deg] and the straight line A1. For example, when an intersection between a straight line representing Δβ = 0.2 [deg] (shown as a broken line B1 in FIG. 5A) and the straight line A1 is obtained, and the value on the horizontal axis at that time is read, a value of 2853 [MPa] is obtained. Is obtained. Similarly, storage elastic modulus under a temperature environment of −5 ° C. corresponding to Δβ = −0.3, −0.2, −0.1, 0, 0.1 and 0.3 [deg] is obtained. Asked.

  Next, the relationship between the storage elastic modulus in the temperature environment of 25 degreeC and (DELTA) (beta) was calculated | required similarly to the case of -5 degreeC temperature environment.

  FIG. 5B is a graph showing the relationship between the storage elastic modulus of Samples Q-1 to Q-3 in a temperature environment of 25 ° C. and Δβ of Samples Q-1 to Q-3 shown in FIG. 4A. . The graph shown in FIG. 5B is a graph with the storage elastic modulus in a temperature environment of 25 ° C. on the horizontal axis and Δβ on the vertical axis.

  In the same manner as in the case of a temperature environment of −5 ° C., an approximate straight line was obtained from the set of storage elastic modulus and Δβ plotted for samples Q-1 to Q-3 by the least square method. The approximate straight line is shown as a straight line A2 in FIG. 5A. Furthermore, storage elastic modulus under a temperature environment of 25 ° C. corresponding to Δβ = −0.3, −0.2, −0.1, 0, 0.1, 0.2 and 0.3 [deg]. Asked.

  Table 1 below shows the storage elastic modulus in a temperature environment of −5 ° C. and the storage elastic modulus in a temperature environment of 25 ° C. corresponding to each Δβ.

  Further, the relationship between Δβ and the storage elastic modulus of the intermediate layer under a certain temperature environment is obtained for each of the samples T-1 to T-3 by the same procedure as that for the samples Q-1 to Q-3. It was.

  FIG. 6A is a graph showing the relationship between the storage elastic modulus of Samples T-1 to T-3 in a temperature environment of −5 ° C. and Δβ of Samples T-1 to T-3 shown in FIG. 4B. is there. The graph shown in FIG. 6A is a graph with the storage elastic modulus in a temperature environment of −5 ° C. as the horizontal axis and Δβ as the vertical axis. For example, as for sample T-1, the storage elastic modulus in a temperature environment of −5 ° C. read from FIG. 2 is 2980 [MPa] as in sample Q-1. On the other hand, the difference Δβ between the warp angle under the temperature environment of −5 ° C. and the warp angle under the temperature environment of 25 ° C. is −0.3 [deg]. Therefore, for sample T-1, the point (2980, -0.3) will be plotted. The same procedure is followed for sample T-2 and sample T-3.

  Next, an approximate straight line was obtained from the set of storage elastic modulus and Δβ plotted for samples T-1 to T-3 by the method of least squares. The approximate straight line is shown as a straight line A3 in FIG. 6A.

  Next, from the intersection of the straight line of Δβ = (constant) [deg] and the straight line A3, Δβ = −0.3, −0.2, −0.1, 0, 0.1, 0.2 and The storage elastic modulus in a temperature environment of −5 ° C. corresponding to 0.3 [deg] was obtained.

  Next, the relationship between the storage elastic modulus in the temperature environment of 25 degreeC and (DELTA) (beta) was calculated | required similarly to the case of -5 degreeC temperature environment.

  6B is a graph showing the relationship between the storage elastic modulus of Samples T-1 to T-3 in a temperature environment of 25 ° C. and Δβ of Samples T-1 to T-3 shown in FIG. 4B. . The graph shown in FIG. 6B is a graph with the storage elastic modulus in a temperature environment of 25 ° C. as the horizontal axis and Δβ as the vertical axis.

  In the same manner as in the case of the temperature environment of −5 ° C., an approximate straight line was obtained from the set of storage elastic modulus and Δβ plotted for samples T-1 to T-3 by the least square method. The approximate straight line is shown as a straight line A4 in FIG. 6B. Furthermore, storage elastic modulus under a temperature environment of 25 ° C. corresponding to Δβ = −0.3, −0.2, −0.1, 0, 0.1, 0.2 and 0.3 [deg]. Asked.

Table 2 below shows the storage elastic modulus under a temperature environment of −5 ° C. and the storage elastic modulus under a temperature environment of 25 ° C. corresponding to each Δβ.

  From Tables 1 and 2, the following was found. By setting the storage elastic modulus at −5 ° C. of the material of the intermediate layer to 2860 MPa to 2950 MPa and the storage elastic modulus at 25 ° C. to 1850 MPa to 2440 MPa, the absolute value of Δβ is about 0.2 [deg] or less. It was confirmed that it could be suppressed. Furthermore, the absolute value of Δβ is about 0.1 [deg] by setting the storage elastic modulus at −5 ° C. of the material of the intermediate layer to 2880 MPa to 2920 MPa and the storage elastic modulus at 25 ° C. to 2000 MPa to 2280 MPa. It was confirmed that the following can be suppressed. That is, it was confirmed that the warpage of the optical disk at low temperatures can be reduced when the storage elastic modulus at −5 ° C. and the storage elastic modulus at 25 ° C. of the intermediate layer material are within the above-described ranges.

  The reason why | Δβ | = 0.2 [deg] is used as a criterion is that R-skew is −0.35 to +0.35 in consideration of signal characteristics, reliability, and the like of BD (Blu-ray Disc). This is based on what is required to be [deg]. That is, within a range of 0.7 [deg] of −0.35 to +0.35 [deg], skew change with time, Sudden change (skew change due to sudden temperature environment change), skew margin in environment change, manufacturing It is necessary to include a skew margin. Considering these skew changes over time, Sudden change, skew margin in environmental change, and skew margin in manufacturing, skew margin in environmental change (that is, skew change under a temperature environment of −5 ° C.) is at least. It must be 0.2 [deg] or less.

  In addition, as shown in FIG. 2, generally, the ultraviolet curable resin composition has a large storage elastic modulus in a temperature environment lower than room temperature. Therefore, even if the disc warpage is large at room temperature (25 ° C.), if | Δβ | is small, it is possible to perform good reproduction of the disc. In other words, if | Δβ | is smaller, the allowable value of R-skew at room temperature can be increased. That is, the manufacturable range of R-skew is increased, and the yield of the optical information recording medium to be manufactured is improved. From the above viewpoint, | Δβ | = 0.1 [deg] or less is more preferable in terms of facilitating the production of the optical information recording medium.

  It should be noted that even when the information signal layer is five layers or more, it is considered that the same discussion as above can be applied by analogy. As described above, when the information signal layers are four layers (samples Q-1 to Q-3), the total thickness of the intermediate layers S1 to S3 and three layers (samples T-1 to T-) The difference from the sum of the thicknesses of the intermediate layers S1 and S2 in 3) is only about 3.5 μm. Therefore, if the sum of the thicknesses of the intermediate layers is substantially equal, | Δβ | is expected to be within the same range.

[Evaluation]
The storage elastic modulus at −5 ° C. of the material of the light transmission layer 2 is 1500 MPa or less, the storage elastic modulus at −5 ° C. of the material of the intermediate layer is 2860 MPa to 2950 MPa, and the storage elastic modulus at 25 ° C. is 1850 MPa to 2440 MPa. By doing so, it was confirmed that | Δβ | could be suppressed to about 0.2 [deg] or less.

  The optical information recording medium is supposed to be used in an environment of 5 ° C. or less and the warpage must be controlled. However, the lower the temperature, the more the storage elastic modulus of the plastic material used in the optical information recording medium. The warpage changes greatly compared to room temperature. When the temperature of the polycarbonate substrate used as the substrate 1 becomes low, the storage elastic modulus increases, and in addition, the polycarbonate substrate contracts due to temperature expansion, and works to change the warp of the disk positively. On the other hand, the cured product of the ultraviolet curable resin composition used for the intermediate layers S1 to S3 and the like has a large storage elastic modulus at low temperatures, so that the curing shrinkage is greatly effective, and the warpage is negative. Work to change. For this reason, if the shrinkage balance between the substrate and the resin cured product of the intermediate layer is not balanced, the warpage changes to the plus side or the minus side.

  Since the curing shrinkage of the intermediate layers S1 to S3 cannot be changed greatly, in the present technology, the storage elastic modulus is balanced so that the storage elastic modulus of the intermediate layers S1 to S3 is within a certain range. The balance between the shrinkage of the intermediate layers S1 to S3 and the shrinkage of the substrate 1 is balanced, and the change in warpage is suppressed. According to the present technology, an optical information recording medium manufactured so that R-skew is within a range of −0.35 to +0.35 [deg] at room temperature, even in an environment of −5 ° C., Or it can control that curvature changes greatly to the minus side.

  The present technology is not limited to the above-described embodiments, and various modifications and applications can be made without departing from the gist of the present technology.

DESCRIPTION OF SYMBOLS 1 Substrate 2 Light transmission layer 3 Hard coat layer 4 Barrier layer L0 to L3 Information signal layer S1 to S3 Intermediate layer 10 Optical information recording medium

Claims (5)

A substrate,
Three or more information signal layers formed on the substrate;
Two or more intermediate layers interposed between the three or more information signal layers;
A light transmission layer formed on the information signal layer located farthest from the substrate,
The storage elastic modulus of the light transmission layer at −5 ° C. is approximately 1200 MPa ,
The storage elastic modulus of each of the two or more intermediate layers at −5 ° C. is 2860 MPa or more and 2950 MPa or less,
An optical information recording medium in which the storage elastic modulus of each of the two or more intermediate layers at 25 ° C. is 1850 MPa or more and 2440 MPa or less. The storage elastic modulus of each of the two or more intermediate layers at −5 ° C. is 2880 MPa or more and 2920 MPa or less,
The optical information recording medium according to claim 1, wherein the storage elastic modulus of each of the two or more intermediate layers at 25 ° C is 2000 MPa or more and 2280 MPa or less.   The optical information recording medium according to claim 1, wherein the light transmission layer contains an ultraviolet curable resin composition as a main component.   4. The optical information recording medium according to claim 1, wherein a total thickness of the two or more intermediate layers is 40 μm or more and 49.5 μm or less.   The optical information recording medium according to claim 1, wherein the substrate is mainly composed of a polycarbonate-based resin.

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