JP2006190358A - Method of manufacturing optical recording medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method capable of manufacturing an optical recording medium, in which data recording and reproducing characteristics can be prevented from being deteriorated even when a resin layer functioning as a light transmission layer or a transparent intermediate layer is formed on an information layer by applying a resin composition on the information layer. <P>SOLUTION: In the method of manufacturing the optical recording medium, the resin composition, which does not cause air bubbles when being left under the environment of ≤70kPaG pressure for five minutes, is applied on the information layer formed on a substrate, thereby forming the resin layer. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for producing an optical recording medium, and more specifically, a resin layer that functions as a light transmission layer or a transparent intermediate layer by applying a resin composition on the information layer, The present invention relates to a method for manufacturing an optical recording medium capable of manufacturing an optical recording medium in which deterioration of data recording / reproducing characteristics is effectively prevented even when formed on a layer.

  Conventionally, optical recording media represented by CDs and DVDs have been widely used as recording media for recording digital data. However, in recent years, they have a larger capacity and a higher data transfer rate. Generation-type optical recording media are being actively developed.

  In such a next-generation optical recording medium, in order to increase the recording capacity and realize a very high data transfer rate, the beam spot diameter of the laser beam used for data recording and reproduction is inevitably very high. In order to reduce the tilt margin to a level similar to that of a conventional optical recording medium such as a DVD, the thickness of the light transmission layer having light transmittance and transmitting a laser beam is required. It is required to be thinner than a substrate of a conventional optical recording medium.

  Therefore, in the next-generation optical recording medium, for example, a laser beam having a wavelength of about 400 nm and an objective lens having a numerical aperture NA of about 0.85 are used, and further, 20 μm to 300 μm on the information layer. A light transmissive layer having a thickness of preferably 50 μm to 150 μm is formed.

  As a method for producing an optical recording medium having a light transmission layer having a thickness of 20 μm to 300 μm, for example, a radiation curable resin composition is applied on the information layer by a coating method such as a spin coating method. Forming a coating film, irradiating the coating film with radiation, curing the radiation curable resin composition, and forming a light transmission layer comprising a resin layer on the information layer, thereby forming a light transmission layer A resin film formed of a light-transmitting material with a resin composition coated on the information layer by a method of manufacturing an optical recording medium having a film formed thereon or a coating method such as a spin coating method. A method of manufacturing an optical recording medium on which a light transmission layer is formed by forming a light transmission layer including a resin layer and a resin film by bonding to the layer is known.

  However, in an optical recording medium in which a light transmission layer made of a resin layer is formed by coating a resin composition on an information layer, when data recorded on the optical recording medium is reproduced, There has been a problem that noise becomes large or a reproduction signal becomes an error, and data recording / reproduction characteristics of the optical recording medium deteriorate.

  In particular, in a rewritable optical recording medium in which a light transmission layer made of a resin layer is formed by coating a resin composition on an information layer, data recorded on the optical recording medium is replaced with new data. When the data is directly overwritten, the data recording / reproduction characteristics of the optical recording medium are greatly deteriorated. Further, when the data recorded on the optical recording medium is repeatedly overwritten with new data, the light transmission layer May peel off, or a minute crack may occur in the light transmission layer, resulting in a problem that the data recording / reproducing characteristics of the optical recording medium are significantly deteriorated.

  On the other hand, the same applies to an optical recording medium having a plurality of information layers stacked by applying a resin composition onto an information layer formed on a support substrate, with a transparent intermediate layer formed therebetween. In addition, there is a problem that the data recording / reproducing characteristics of the optical recording medium deteriorate.

  Therefore, an object of the present invention is to provide data recording even when a resin layer functioning as a light transmission layer or a transparent intermediate layer is formed on an information layer by coating the resin composition on the information layer. An object of the present invention is to provide an optical recording medium manufacturing method capable of manufacturing an optical recording medium in which deterioration of reproduction characteristics is effectively prevented.

  In conventional optical recording media such as CD and DVD, the resin layer functioning as a light transmission layer, that is, the substrate is usually formed of a resin such as polycarbonate by an injection molding method. The hard coat layer of the medium is formed by applying the resin composition by a coating method such as spin coating, but the thickness is about 3 μm to 5 μm. Therefore, the data recording / reproducing characteristics of the optical recording medium are not deteriorated. Therefore, when a resin layer having a thickness of 20 μm to 300 μm is formed by coating the resin composition, The cause of the deterioration of the data recording / reproducing characteristics of the recording medium has not been clarified.

  Therefore, in order to achieve the above-mentioned object of the present invention, the present inventor has conducted extensive research, and as a result, when a resin layer having a thickness of 20 μm to 300 μm is formed by applying a resin composition, The reason why the data recording / reproducing characteristics of the optical recording medium deteriorates is that when the resin composition is applied, a part of the air dissolved in the resin composition is separated as a gas, and the inside of the applied resin composition In addition, it was found that bubbles having a diameter of about 1 μm to 10 μm were generated, and the bubbles remained in the resin layer formed by the applied resin composition.

  As a result of further research based on such knowledge, the present inventor has found that bubbles dissolved when the air dissolved in the resin composition is allowed to stand for 5 minutes in an environment where the pressure is −70 kPaG or less. When the resin composition was applied and formed to form a resin layer, oxygen dissolved in the resin composition was separated as a gas and applied. It has been found that bubbles can be effectively prevented from occurring in the resin composition.

  The present invention is based on such knowledge, and according to the present invention, the object of the present invention is to stand on an information layer formed on a support substrate for 5 minutes in an environment where the pressure is -70 kPaG or less. This is achieved by a method for producing an optical recording medium, wherein a resin layer is formed by applying a resin composition in which bubbles are not generated.

  In the present invention, “a resin composition that does not generate bubbles when allowed to stand for 5 minutes in an environment where the pressure is −70 kPaG or less” means that the resin composition is put into a sealed container, When the pressure is reduced to −70 kPaG or less using a device such as a vacuum pump, it is confirmed that no bubbles are visually observed in the charged resin composition for 5 minutes from the start of the pressure reduction. means.

  When the resin composition for forming the resin layer contains a volatile component such as a solvent, the solid content of the resin composition excluding these volatile components generates bubbles under the above conditions. If there is no.

  In the present invention, the “information layer” means at least a one-layer or two-layer write-once recording film containing an organic dye or an inorganic material, a rewritable recording film containing a phase change material, or a read-only prepit. A layer including the surface of the support substrate on which is formed. In the present invention, the configuration of the information layer is not particularly limited, and may include one or more dielectric films, one or more reflective films, and one or more protective films.

  Data recording / reproduction characteristics are deteriorated in an optical recording medium in which a resin composition is applied onto an information layer using a coating method such as spin coating to form a resin layer that functions as a light transmission layer or a transparent intermediate layer. This is because part of air or oxygen dissolved in the resin composition is separated as a gas, bubbles are generated in the applied resin composition, and once bubbles are generated. As a result, it is difficult for bubbles to be released from the applied resin composition, and as a result, bubbles are likely to remain in the resin layer formed of the applied resin composition. In particular, the resin layer has a thickness of 20 μm to 300 μm. If it has, or before the applied resin composition is cured, another film or the like is laminated on the surface, or a stamper or the like is placed, the bubble is further applied. Resin composition This is considered to be caused by the fact that bubbles are less likely to be released from the product and bubbles are likely to remain in the resin layer formed of the applied resin composition. That is, when bubbles remain in the resin layer functioning as a light transmission layer or a transparent intermediate layer, the laser beam applied to the optical recording medium during data recording / reproduction is generated by the bubbles. In particular, when the optical recording medium is configured as a next generation optical recording medium, the beam spot diameter of the laser beam irradiated onto the optical recording medium is very small. As a result, when the data recorded on the optical recording medium is reproduced, the noise of the reproduction signal increases, and in some cases, the reproduction signal is considered to cause an error. In particular, when the optical recording medium is configured as a rewritable optical recording medium, bubbles remaining in the resin layer functioning as a light transmission layer or a transparent intermediate layer are subjected to a thermal history by direct overwrite. It is considered that the data recording / reproducing characteristics are likely to deteriorate because the resin layer peels off or a minute crack is generated in the resin layer due to volume change.

  However, according to the present invention, the resin composition to be applied by an application method such as a spin coating method is such that bubbles are not generated when left under an environment where the pressure is −70 kPaG or less for 5 minutes. Until the air is not dissolved, even if the resin composition is applied by an application method such as a spin coating method, the air dissolved in the resin composition is separated and applied as a gas. In the next-generation optical recording medium in which a laser beam with a very small beam spot diameter is used during recording and reproduction, it is possible to effectively prevent the occurrence of bubbles in the resin composition. The laser beam incident on the resin layer is not irregularly reflected. Further, in the rewritable optical recording medium, the resin layer Even if the thermal history is received, the resin layer does not peel or the micro crack does not occur in the resin layer. Therefore, when the data recorded on the optical recording medium is reproduced, the noise of the reproduction signal can be reduced. Even if a resin layer that functions as a light transmission layer or a transparent intermediate layer is formed by coating the resin composition, it is possible to reliably prevent an error in the reproduction signal. It is possible to effectively prevent the deterioration of the data recording / reproducing characteristics.

  In the present invention, the resin composition is preferably a resin composition that does not generate bubbles when allowed to stand for 5 minutes in an environment having a pressure of −80 kPaG or less. When the resin composition does not generate bubbles when left under an environment where the pressure is −80 kPaG or less for 5 minutes, when this resin composition is applied to form a resin layer, It is possible to more effectively prevent bubbles from being generated in the applied resin composition.

  In the present invention, a resin composition that functions as a light transmission layer, a part of the light transmission layer, or a transparent intermediate layer is formed by coating the resin composition on the information layer of the optical recording medium.

  In a preferred embodiment of the present invention, the resin layer is formed by one surface thereof as a light transmission layer constituting a light incident surface on which a laser beam is incident.

  According to a preferred embodiment of the present invention, even if a resin layer having a thickness of 20 μm to 300 μm is formed by applying a resin composition having a relatively high viscosity, the resin composition is applied within the applied resin composition. Since it is possible to effectively prevent the generation of bubbles, the next-generation type of resin layer itself formed in this way is used as it is, with one surface constituting a light incident surface on which a laser beam is incident. It can function as a light transmission layer of an optical recording medium. Therefore, when a resin layer that functions as a light transmission layer is formed by applying a resin composition, data recording / reproduction characteristics are deteriorated. It is possible to manufacture an optical recording medium in which the above is effectively prevented with high productivity.

  In another preferred embodiment of the present invention, a resin composition is applied on the information layer to form a resin layer, and light is transmitted through the resin layer formed on the information layer. A resin film formed of a material having transparency is bonded to the information layer to form a light transmission layer including the resin layer and the resin film.

  According to another preferred embodiment of the present invention, before the resin composition applied on the information layer is cured, a resin film is laminated on the surface, and bubbles generated in the applied resin composition are extremely generated. Even if it becomes difficult to be released, it is possible to effectively prevent bubbles from being generated in the applied resin composition. Therefore, by applying the resin composition, the formed resin layer is changed into a light transmitting layer. It can be made to function as an adhesive layer for adhering a resin film to a support substrate, and thus can form part of a light transmission layer by applying a resin composition. Even when the resin layer functioning as the light transmission layer is formed, it is possible to manufacture an optical recording medium in which deterioration of data recording / reproducing characteristics is effectively prevented.

  In this embodiment, the method for forming the resin film and the method for forming the light transmission layer including the resin layer and the resin film by bonding the resin film to the information layer via the resin layer are particularly limited. It is not something.

  In the present embodiment, the resin composition is preferably applied so that the thickness of the resin layer to be formed is 20 μm or more, and more preferably 25 μm or more.

  In still another preferred embodiment of the present invention, a resin layer is formed by applying a resin composition on the information layer, and at least one other information layer is formed on the resin layer. Is done.

  According to still another preferred embodiment of the present invention, before the resin composition applied on the information layer is cured, a stamper or the like is placed on the surface of the resin composition, and bubbles generated in the applied resin composition are generated. Even if it is very difficult to release, it is possible to effectively prevent the generation of bubbles in the applied resin composition. Therefore, by applying the resin composition, the resin layer formed can be reduced to 2 It is formed between two information layers and has the function of separating the two information layers physically and optically at a sufficient distance, and can function as a transparent intermediate layer having optical transparency. Therefore, even when a resin layer that functions as a transparent intermediate layer is formed by applying the resin composition, the data recording / reproducing characteristics of the information layer on which the transparent intermediate layer is formed deteriorates. Can be effectively prevented, and at least one additional information layer can be formed on the transparent intermediate layer to produce an optical recording medium having a plurality of information layers. become.

  In the present embodiment, a method for forming at least one other information layer on the formed resin layer by applying the resin composition is not particularly limited. The information layer can be formed by sequentially stacking a reflective film, a recording film, and the like.

  According to further research by the inventor, it is certain that the data recording / reproducing characteristics of the optical recording medium will deteriorate if bubbles can be prevented from occurring in the resin layer formed closer to the information layer. It has been found that it can be prevented.

  Therefore, in this invention, it is preferable that the resin layer formed by apply | coating a resin composition is in contact with the information layer.

  In the present invention, a resin composition that does not generate bubbles when left under an environment where the pressure is −70 kPaG or less for 5 minutes is left when the resin composition is left under an environment where the pressure is −70 kPaG or less for 5 minutes. If it is a resin composition that does not generate bubbles, it is not particularly limited. For example, it has a property that it is difficult to dissolve air or the like, and when left in an environment where the pressure is −70 kPaG or less for 5 minutes. Further, it may be a resin composition that does not generate bubbles, and is degassed in advance to such an extent that bubbles do not occur when left under an environment where the pressure is −70 kPaG or less for 5 minutes. A resin composition from which dissolved air or the like is removed may be used.

  In the present invention, the resin composition has the property that it is difficult to dissolve air or the like, and is not particularly limited as a resin composition that does not generate bubbles when left under an environment where the pressure is −70 kPaG or less for 5 minutes. The resin composition having such properties can be arbitrarily selected and used.

  Further, in the present invention, a resin that has been deaerated in advance to such an extent that bubbles are not generated when left under an environment of -70 kPaG or less for 5 minutes, and dissolved air or the like is removed. The composition is not particularly limited, and a resin composition obtained by degassing a resin composition described later can be arbitrarily selected and used.

  In the present invention, the resin composition that does not generate bubbles when left standing for 5 minutes in an environment where the pressure is −70 kPaG or less is previously degassed, and under an environment where the pressure is −70 kPaG or less. A resin composition that does not generate bubbles when allowed to stand for 5 minutes is preferable because it can surely prevent bubbles from being generated in the applied resin composition. When it is treated and the pressure is not more than −80 kPaG for 5 minutes, it is a resin composition that does not generate bubbles when left standing, and that bubbles are generated in the applied resin composition. This is preferable in that it can be surely prevented.

  In the present invention, the deaeration treatment for removing air or the like from the resin composition is not particularly limited, and the vacuum deaeration treatment, the ultrasonic deaeration treatment, the centrifugal deaeration treatment, the heating deaeration treatment, the membrane Separation and deaeration treatments may be mentioned, and among these deaeration treatments, only one type may be used, or two or more types may be used in combination. Further, it is sufficient to perform the deaeration process once, but it can be performed in two or more steps. Among these degassing treatments, the degassing efficiency is high, and continuous degassing treatment is possible regardless of the viscosity of the resin composition. A treatment combining sonic deaeration treatment or heat deaeration treatment is preferably applied.

  The treatment conditions in these deaeration treatments are not particularly limited, and are appropriately selected according to the viscosity and the processing amount of the resin composition to be deaeration treatment, and the resin composition after the deaeration treatment, What is necessary is just to set it as the conditions which can remove the air etc. which are melt | dissolved in the resin composition to such an extent that even if it is left to stand for 5 minutes in the environment where a pressure is -70 kPaG or less, a bubble is not generated. For example, the processing conditions of the vacuum degassing treatment are not particularly limited, but as an example, the resin composition is put into a sealed container and a device such as a vacuum pump is installed at a temperature of 20 ° C. to 60 ° C. The conditions are such that the inside of the container is continuously depressurized, and the deaeration treatment is performed for a predetermined time, for example, 1 hour to 24 hours in an environment where the pressure is -40 kPaG or less, preferably -80 kPaG or less. It is done. At this time, in order to further increase the deaeration efficiency, the resin composition is preferably put into a sealed container so that its surface area is increased, or is preferably stirred by a stirring device.

  In the present invention, the resin composition has a property that it is difficult to dissolve air or the like, and a resin composition that does not generate bubbles when left under an environment where the pressure is −70 kPaG or less for 5 minutes, or to the extent that bubbles are not generated. The resin composition that has been degassed in advance and removed dissolved air or the like is preferably a radiation curable resin composition in that a resin layer can be easily formed, and an ultraviolet curable resin composition. More preferably, it is a product.

  In the present invention, the “radiation curable resin composition” refers to a resin composition that is cured by radiation, and the “radiation” includes ultraviolet rays, electron beams, heat rays, and visible light.

  As the radiation curable resin composition, an ultraviolet curable resin composition that cures when irradiated with ultraviolet rays, an electron beam curable resin composition that begins to cure when irradiated with an electron beam, and heat rays are irradiated. Can be exemplified by a heat ray curable resin composition that starts to be cured by irradiation, and a visible light curable resin composition that starts to be cured by irradiation with visible light. Among these, an ultraviolet curable resin composition and an electron beam can be used. A curable resin composition is preferably used for forming a resin layer, and a (meth) acrylic ultraviolet curable resin composition and an epoxy ultraviolet curable resin composition are particularly preferable.

  These ultraviolet curable resin compositions contain an oligomer that can undergo a polymerization reaction when irradiated with ultraviolet rays, and the oligomer is not particularly limited, but includes at least a radical polymerizable group in the molecule. Preferably one, for example, urethane (meth) acrylate oligomer, epoxy (meth) acrylate oligomer, polyester (meth) acrylate oligomer, polyether containing at least one radical polymerizable group in the molecule Examples include (meth) acrylate oligomers.

  This oligomer may be used alone or in combination of two or more.

  In the present invention, the radical polymerizable group is not particularly limited as long as it is a group capable of undergoing a polymerization reaction by irradiation with ultraviolet rays, and examples thereof include an acryloyl group, a methacryloyl group, a vinyl group, and an allyl group. It is done.

  The ultraviolet curable resin composition contains an oligomer capable of undergoing a polymerization reaction when irradiated with ultraviolet rays, and this oligomer is preferably a solventless oligomer.

  The ultraviolet curable resin composition preferably further contains a monomer capable of undergoing a polymerization reaction in addition to an oligomer capable of undergoing a polymerization reaction when irradiated with ultraviolet rays. When the ultraviolet curable resin composition contains such a monomer, the viscosity of the ultraviolet curable resin composition can be adjusted to a desired viscosity, and the adhesion with the information layer can be improved and formed. It is possible to increase the crosslink density of the resin layer.

  The monomer capable of undergoing a polymerization reaction by irradiation with ultraviolet rays is not particularly limited, but preferably contains at least one radical polymerizable group in the molecule.

  The monomer containing one radical polymerizable group in the molecule is not particularly limited, and examples thereof include 2-hydroxyethyl (meth) acrylate, dicyclopentanyl (meth) acrylate, and isobornyl (meth). Examples include acrylates, morpholine acrylates, phenoxy (meth) acrylates, tetrahydrofurfuryl (meth) acrylates, cyclohexyl acrylates and the like, and monomers that contain two or more radical polymerizable groups in the molecule are particularly limited But, for example, ethylene oxide modified bisphenol A di (meth) acrylate, bis (acryloxyneopentyl glycol) adipate, 1,4-butanediol diacrylate, dicyclopentanyl diacrylate, 1,6-hexane All diacrylate, neopentyl glycol di (meth) acrylate trimethylolpropane triacrylate, tris ((meth) acryloxyethyl) isocyanurate, pentaerythritol tetra (meth) acrylate, dipentaerythritol hexa (meth) acrylate, trimethylol Examples thereof include propane triacrylate.

  As the monomer capable of undergoing a polymerization reaction by irradiation with ultraviolet rays, only one type may be used, or two or more types may be used in combination.

  The ultraviolet curable resin composition preferably further contains a photopolymerization initiator in addition to the oligomer capable of undergoing a polymerization reaction when irradiated with ultraviolet rays. When the ultraviolet curable resin composition contains a photopolymerization initiator, the curing rate of the resin composition can be improved.

  The photopolymerization initiator is not particularly limited, and examples thereof include a benzoin photopolymerization initiator, an acetophenone photopolymerization initiator, a thioxanthone photopolymerization initiator, and a peroxide photopolymerization initiator.

  In the present invention, since the resin layer functions as a light transmission layer or a transparent intermediate layer of the optical recording medium, it has a high light transmission with respect to the wavelength region of the laser beam incident on the light transmission layer or the transparent intermediate layer. Therefore, it is preferable to use a photopolymerization initiator having no absorption in the wavelength region of 380 nm to 450 nm as the photopolymerization initiator. As the initiator, for example, benzophenone, diethoxyacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-hydroxycyclohexyl phenyl ketone, methylbenzoinformate and the like are preferably used.

  These photopolymerization initiators may be used alone or in combination of two or more.

  In the present invention, the ultraviolet curable resin composition only needs to contain an oligomer that can undergo a polymerization reaction when irradiated with ultraviolet rays, and preferably, a monomer that can undergo a polymerization reaction when irradiated with ultraviolet rays and a photopolymerization. Contains additives such as initiators, sensitizers, photoinitiator aids, organic fillers, polymerization inhibitors, antioxidants, light stabilizers, antifoaming agents, leveling agents, pigments, antistatic agents, if desired. May be.

  In the present invention, the resin layer is formed by applying a resin composition that does not generate bubbles when left in an environment of a pressure of −70 kPaG or less for 5 minutes to form the resin layer. The method is not particularly limited as long as it is a method that can perform the above.

  The method for applying the resin composition is not particularly limited. For example, spin coating, slot coating, roll coating, blade coating, air knife coating, gate roll coating, bar coating, size, etc. The press method, spray coating method, gravure coating method, curtain coating method, rod blade coating method, lip coating method, slit die coating method, etc. are preferably applied for applying the resin composition, and in particular, the spin coating method is produced. It is preferably applied in terms of excellent properties.

  As a method of applying the resin composition by spin coating, for example, a radiation curable resin composition is applied on the information layer by spin coating to form a coating film, and the coating film is irradiated with radiation. And the method of hardening a radiation-curable resin composition and forming a resin layer on an information layer is preferable. Thus, when the resin layer is formed, the productivity is excellent. In particular, when a radiation curable resin composition that has been degassed in advance is used, the productivity is excellent and the curing rate of the resin layer is high. Even if the optical recording medium is stored for a long period of time, warping of the resin layer can be effectively prevented, and the reliability of the optical recording medium can be improved.

  Thus, when forming a resin layer, the conditions at the time of apply | coating a radiation curable resin composition by a spin coating method are not specifically limited.

  Further, in the case of forming the resin layer in this way, the atmosphere when irradiating the applied radiation curable resin composition with radiation is not particularly limited, but the radiation is in the air or It is preferable to irradiate the radiation curable resin composition in an inert gas atmosphere. Furthermore, it is sufficient that a sufficient amount of radiation is applied to cure the radiation curable resin composition. The absorbed dose and the like are not particularly limited, and radiation may be applied to the radiation curable resin composition in two or three or more times.

  According to the present invention, even when a resin layer that functions as a light transmission layer or a transparent intermediate layer is formed on the information layer by applying the resin composition on the information layer, the data recording / reproducing characteristics are obtained. It is possible to provide an optical recording medium manufacturing method capable of manufacturing an optical recording medium in which deterioration is effectively prevented.

  Therefore, the optical recording medium manufactured by the method for manufacturing an optical recording medium of the present invention can record data and reproduce the data as desired.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a partially cutaway schematic perspective view of an optical recording medium manufactured by an optical recording medium manufacturing method according to a preferred embodiment of the present invention, and FIG. 2 is a portion indicated by A in FIG. FIG.

  As shown in FIGS. 1 and 2, the optical recording medium 10 according to this embodiment is formed in a disc shape, and has an outer diameter of about 120 mm and a thickness of about 1.2 mm.

  In the optical recording medium 10 according to this embodiment, an objective lens having a numerical aperture NA satisfying λ / NA ≦ 640 by a laser beam L having a wavelength of 380 nm to 450 nm from the direction indicated by an arrow L in FIG. The light transmission layer 16 is configured to be irradiated via a not-shown).

  An optical recording medium 10 according to the present embodiment is configured as a write-once type optical recording medium, and as shown in FIG. 2, a support substrate 11 and an information layer formed on one surface of the support substrate 11. 20 and a light transmission layer 16 formed on the information layer 20.

  The support substrate 11 functions as a support for ensuring the mechanical strength required for the optical recording medium 10 and a thickness of about 1.2 mm. The material used to form the support substrate 11 is not particularly limited as long as it can function as a support for the optical recording medium 10. In this embodiment, the support substrate 11 is made of workability, It is made of polycarbonate resin from the viewpoint of optical characteristics.

  As shown in FIG. 2, on the surface of the support substrate 11, grooves 11a and lands 11b are spirally formed alternately from the vicinity of the center toward the outer edge. The grooves 11 a and / or lands 11 b formed on the surface of the support substrate 11 function as guide tracks for the laser beam L. The depth of the groove 11a is not particularly limited, but is preferably set to 10 nm to 40 nm, and the track pitch of the groove 11a and the land 11b is not particularly limited, but is 0.2 μm to 0 μm. It is preferable to set to 4 μm.

  As shown in FIG. 2, the information layer 20 includes a reflective film 12 formed on the surface of the support substrate 11, a second dielectric film 13 formed on the reflective film 12, and a second dielectric material. A second recording film 14b formed on the film 13, a first recording film 14a formed on the second recording film 14b, and a first dielectric formed on the first recording film 14a. And a film 15.

  The reflection film 12 has a function of reflecting the incident laser beam L through the light transmission layer 16 and emitting it again from the light transmission layer 16, and further, a reproduction signal (C / N ratio) due to the multiple interference effect. It has a function to improve.

  The material used for forming the reflective film 12 is not particularly limited as long as it can reflect the laser beam L. For example, it is formed of Al, Ti, Cr, Cu, Ag, Au, or the like. Can do. The thickness of the reflective film 12 is not particularly limited, but is preferably 20 nm to 200 nm.

  The first dielectric film 15 and the second dielectric film 13 serve to protect the first recording film 14a and the second recording film 14b.

  The material for forming the first dielectric film 15 and the second dielectric film 13 is not particularly limited as long as it is a transparent dielectric material in the wavelength region of the laser beam L. For example, The first dielectric film 15 and the second dielectric film 13 can be formed of a dielectric material mainly composed of oxide, sulfide, nitride, carbide, or a combination thereof. The first dielectric film 15 and the second dielectric film 13 may be formed of the same dielectric material, but may be formed of different dielectric materials. Furthermore, at least one of the first dielectric film 15 and the second dielectric film 13 may have a multilayer structure including a plurality of dielectric films. The thicknesses of the first dielectric film 15 and the second dielectric film 13 are not particularly limited, but are preferably 3 nm to 200 nm.

  The first recording film 14a contains Si as a main component, and the second recording film 14b contains CuAl as a main component.

  When the information layer 20 of the optical recording medium 10 is irradiated with a laser beam, CuAl contained as a main component in the second recording film 14b and Si contained as a main component in the first recording film 14a. However, they are quickly mixed to form a mixed area and form a recording mark. Thus, the reflectance of the area of the recording layer where the recording mark is formed by mixing Si and CuAl is significantly different from the reflectance of the blank area where the recording mark is not formed. Can be recorded.

  In this embodiment, the second recording film 14b containing CuAl as a main component and the first recording film 14a containing Si as a main component are both formed to have a thickness of 3 nm or more and 30 nm or less. Has been.

  The light transmission layer 16 is a layer through which the laser beam is transmitted, and a light incident surface 16a on which the laser beam is incident is constituted by one surface thereof. Although the material used in order to form the light transmissive layer 16 is not specifically limited, It is formed with the above-mentioned resin composition. The light transmission layer 16 preferably has a thickness of 20 μm to 300 μm, and more preferably has a thickness of 50 μm to 150 μm. In the optical recording medium 10 according to this embodiment, the light transmission layer 16 has a thickness of 100 μm.

  According to this embodiment, the optical recording medium 10 having the above configuration is manufactured as follows.

  First, a support substrate 11 having grooves 11a and lands 11b on one surface is formed by injection molding using a stamper.

  Next, the reflective film 12, the second dielectric film 13, and the second recording film 14b are formed on almost the entire surface of the support substrate 11 on which the grooves 11a and the lands 11b are formed by a vapor phase growth method such as a sputtering method. The first recording film 14a and the first dielectric film 15 are sequentially formed to form the information layer 20.

  Next, the light transmission layer 16 is formed on the surface of the information layer 20.

  In forming the light transmission layer 16, first, an ultraviolet curable resin composition is prepared, and deaerated to such an extent that no bubbles are generated when left under an environment where the pressure is −70 kPaG or less for 5 minutes. It is processed. Preferably, the ultraviolet curable resin composition is deaerated to such an extent that bubbles are not generated when left under an environment where the pressure is −80 kPaG or less for 5 minutes.

  In the present invention, the deaeration treatment for removing air and the like from the ultraviolet curable resin composition is not particularly limited, and is performed under reduced pressure deaeration treatment, ultrasonic deaeration treatment, centrifugal deaeration treatment, heating deaeration. Treatment, membrane separation deaeration treatment, and the like. Among these deaeration treatments, only one type may be used, or two or more types may be used in combination. Further, it is sufficient to perform the deaeration process once, but it can be performed in two or more steps. Among these degassing treatments, vacuum degassing treatment and vacuum degassing treatment are high in that the degassing efficiency is high and continuous degassing treatment is possible regardless of the viscosity of the ultraviolet curable resin composition. A combination of treatment and ultrasonic degassing or heat degassing is preferably applied.

  The treatment conditions in these deaeration treatments are not particularly limited, and are appropriately selected according to the viscosity, the processing amount, etc. of the ultraviolet curable resin composition to be deaerated, and UV curing after the deaeration treatment. The air dissolved in the ultraviolet curable resin composition is degassed to such an extent that bubbles are not generated even if the curable resin composition is allowed to stand for 5 minutes in an environment where the pressure is −70 kPaG or less. What is necessary is just to set to the conditions which can do. For example, the processing conditions of the vacuum degassing treatment are not particularly limited, and as an example, an ultraviolet curable resin composition is put into a hermetically sealed container at a temperature of 20 ° C. to 60 ° C., such as a vacuum pump. Conditions under which the inside of the container is continuously depressurized using an apparatus, and the deaeration treatment is performed for a predetermined time, for example, 1 hour to 24 hours in an environment where the pressure is -40 kPaG or less, preferably -80 kPaG or less. Is mentioned. At this time, in order to further increase the deaeration efficiency, the ultraviolet curable resin composition is preferably put into a sealed container so that the surface area thereof is increased, or is stirred by a stirring device. preferable.

  Next, the ultraviolet curable resin composition that has been degassed in this manner is applied onto the surface of the first dielectric film 15 by a spin coating method to form a coating film. To cure the ultraviolet curable resin composition, and the light transmission layer 16 made of a resin layer is formed on the information layer.

  In the present invention, the conditions for applying the ultraviolet curable resin composition by spin coating are not particularly limited.

  In the present invention, the atmosphere when the ultraviolet curable resin composition applied by the spin coating method is irradiated with ultraviolet rays is not particularly limited, but ultraviolet rays are in air or in an inert gas atmosphere, It is preferable to irradiate the ultraviolet curable resin composition, and it is more preferable to irradiate at a temperature of room temperature (25 ° C.) to about 60 ° C. Further, in the present invention, it is only necessary to irradiate with a sufficient amount of ultraviolet rays for curing the ultraviolet curable resin composition, and the irradiation amount of the ultraviolet rays is not particularly limited. Alternatively, the ultraviolet curable resin composition may be irradiated in three or more times.

  In this way, the light transmission layer 16 is formed on the surface of the information layer 20.

  In this embodiment, an ultraviolet curable resin composition that has been degassed in advance so as not to generate bubbles when allowed to stand for 5 minutes in an environment where the pressure is −70 kPaG or less is applied by a spin coating method. Since the resin layer is formed by coating, the applied UV curable resin composition is used even when the resin layer having a thickness of 100 μm is formed with the UV curable resin composition having a relatively high viscosity. It is possible to effectively prevent the occurrence of bubbles in the resin layer, so that the resin layer formed in this manner can function as the light transmission layer 16 of the next generation type optical recording medium 10, and therefore Even when the resin layer functioning as the light transmission layer 16 is formed by applying an ultraviolet curable resin composition by a spin coating method, data recording is performed. The optical recording medium 10 to the raw characteristics are deteriorated is effectively prevented, with high productivity, it is possible to produce.

  In addition, when the light transmission layer 16 is formed in this manner, the productivity is excellent, and the curing rate of the light transmission layer 16 is extremely high. Even if the optical recording medium 10 is stored for a long period of time, Warpage of the light transmission layer 16 can be effectively prevented, and the reliability of the optical recording medium 10 can be improved.

  In the optical recording medium 10 configured as described above, the light incident surface 16a is irradiated with a laser beam L having a wavelength of, for example, 380 nm to 450 nm from the direction indicated by the arrow in FIG. Played.

  In this embodiment, an ultraviolet curable resin composition that has been degassed in advance so as not to generate bubbles when allowed to stand for 5 minutes in an environment where the pressure is −70 kPaG or less is applied by a spin coating method. Since the light transmission layer 16 is formed by coating, it is effectively prevented that the data recording / reproducing characteristics of the optical recording medium 10 deteriorate. Therefore, the data recorded on the optical recording medium 10 can be stored in a desired manner. It becomes possible to reproduce.

  Examples are given below to clarify the effects of the present invention.

  Optical recording medium sample # 1 was produced as follows.

  First, a disk-shaped polycarbonate substrate having a thickness of 1.1 mm and an outer diameter of 120 mm was produced by an injection molding method.

Next, by sputtering, on the one surface of the polycarbonate substrate, a reflective film having a thickness of 100 nm containing Ag as a main component, and a second dielectric film having a thickness of 25 nm containing a mixture of ZnS and SiO ₂ A second recording film having a thickness of 5 nm containing CuAl as a main component, a first recording film having a thickness of 4 nm containing Si as a main component, and a thickness of 25 nm containing a mixture of ZnS and SiO ₂ . A first dielectric film was sequentially formed to form an information layer.

  Next, 35 parts by mass of urethane acrylate oligomer (UV curable oligomer, manufactured by Toagosei Co., Ltd .: trade name “M-1200”), dicyclopentanyl diacrylate (UV curable monomer, manufactured by Nippon Kayaku Co., Ltd .: trade name) "R-684") 30 parts by mass, trimethylolpropane triacrylate (UV curable monomer, Nippon Kayaku Co., Ltd., trade name: "TMPTA"), 10 parts by mass, cyclohexyl acrylate (UV curable monomer, Osaka Organic Stock) 10 parts by mass, manufactured by company, trade name: “Biscoat 115”) and 5 parts by weight of 1-hydroxycyclohexyl phenyl ketone (photopolymerization initiator, manufactured by Ciba Specialty Chemicals, Inc., trade name: “Irgacure 184”) Part was added and mixed uniformly to prepare an ultraviolet curable resin composition.

  The viscosity of the ultraviolet curable resin composition thus obtained was 5,000 mPa · s when measured at 25 ° C. using a viscosity meter “MR300” (trade name) manufactured by Rheology Co., Ltd.

  Next, the ultraviolet curable resin composition is put into a stirring device in a sealed container, and the temperature in the container is 20 ° C. to 30 ° C., using a vacuum pump, under a reduced pressure of −80 kPaG for 12 hours, The ultraviolet curable resin composition was stirred.

  A part of the ultraviolet curable resin composition thus degassed is put into the sealed container again, and the sealed container is depressurized with a vacuum pump at a temperature in the container of 20 ° C. to 30 ° C. Over 5 minutes from the start (1 minute after the start of decompression, the pressure in the container reached -70 kPaG), the ultraviolet curable resin composition was allowed to stand under a reduced pressure of -70 kPaG to generate bubbles. Observed. As a result, it was confirmed that no bubbles were generated in the ultraviolet curable resin composition for 5 minutes from the start of decompression.

  Further, the support substrate on which the information layer is formed is set in a spin coating apparatus, and 3 g of the degassed UV curable resin composition is discharged onto the surface of the information layer, and the support substrate is moved at a predetermined speed. The UV curable resin composition was spread on the surface of the information layer to form a coating film.

The coating film thus obtained was irradiated with ultraviolet rays at 25 ° C. in air so that the illuminance was 1,000 mW / cm ² and the irradiation amount was 3 J / cm ^2, and the coating film was cured to a thickness of 100 μm. A light transmission layer having a thickness was formed.

  Thus, an optical recording medium sample # 1 was produced.

  Next, instead of the degassing treatment of stirring the ultraviolet curable resin composition for 12 hours under a reduced pressure of -80 kPaG, the ultraviolet curable resin composition for 24 hours under a reduced pressure of -50 kPaG. An optical recording medium sample # 2 was produced in the same manner as the optical recording medium sample # 1 except that the deaeration process was changed to a stationary deaeration process.

  The generation of bubbles was observed in the ultraviolet curable resin composition thus degassed in the same manner as in the optical recording medium sample # 1. As a result, it was confirmed that no bubbles were generated over 5 minutes from the start of decompression.

  Then, instead of the degassing treatment of stirring the ultraviolet curable resin composition for 12 hours under a reduced pressure of -80 kPaG, the ultraviolet curable resin composition for 12 hours under a reduced pressure of -80 kPaG. An optical recording medium sample # 3 was produced in the same manner as the optical recording medium sample # 1 except that the ultrasonic vibration was applied to the sample and the deaeration process was changed.

  The generation of bubbles was observed in the ultraviolet curable resin composition thus degassed in the same manner as in the optical recording medium sample # 1. As a result, it was confirmed that no bubbles were generated over 5 minutes from the start of decompression.

  Then, under the reduced pressure of −80 kPaG, the optical recording medium comparison was performed in the same manner as the optical recording medium sample # 1 except that the deaeration process for stirring the ultraviolet curable resin composition was not performed for 12 hours. Sample # 1 was made.

  The generation of bubbles was observed in the same manner as the optical recording medium sample # 1 for the UV curable resin composition that had not been degassed. As a result, it was confirmed that a large number of bubbles were generated from the start of decompression.

  Then, instead of the degassing treatment of stirring the ultraviolet curable resin composition for 12 hours under a reduced pressure of −80 kPaG, the ultraviolet curable resin composition is applied for 5 minutes under a reduced pressure of −80 kPaG. The optical recording medium comparison sample # 1 is the same as the optical recording medium sample # 1 except that the deaeration process is performed (the pressure in the container reaches −80 kPaG after 1 minute from the start of decompression). 2 was produced.

  The generation of bubbles was observed in the ultraviolet curable resin composition thus degassed in the same manner as in the optical recording medium sample # 1. As a result, it was confirmed that bubbles were generated from the start of decompression.

  Next, instead of the degassing treatment of stirring the ultraviolet curable resin composition for 12 hours under a reduced pressure of −80 kPaG, the ultraviolet curable resin composition is applied for 30 minutes under a reduced pressure of −80 kPaG. The optical recording medium comparison sample # 1 is the same as the optical recording medium sample # 1 except that the deaeration process is performed (the pressure in the container reaches −80 kPaG after 1 minute from the start of decompression). 3 was produced.

  The generation of bubbles was observed in the ultraviolet curable resin composition thus degassed in the same manner as in the optical recording medium sample # 1. As a result, it was confirmed that bubbles were generated.

  Ten optical transmission layers of the optical recording medium samples # 1 to # 3 and the optical recording medium comparative samples # 1 to # 3 thus obtained were arbitrarily selected and observed with an optical microscope. In the light transmissive layers of Samples # 1 to # 3, the presence of bubbles was not observed in any part, whereas in the light transmissive layers of the optical recording medium comparative samples # 1 and # 2, It was found that bubbles were also present at the locations, and bubbles were present at a plurality of locations in the light transmission layer of the optical recording medium comparative sample # 3.

  Next, the optical recording medium samples # 1 to # 3 and the optical recording medium comparison samples # 1 to # 3 are set in an optical recording medium evaluation apparatus “DDU1000” (trade name) manufactured by Pulstec Industrial Co., Ltd. While rotating at a linear velocity of 3 m / sec, the channel clock frequency is 66 MHz, the channel bit length is 0.12 μm / bit, the wavelength is 405 nm, and the power is between the recording power Pw and the base power Pb, The information layer is irradiated with a modulated laser beam according to a predetermined pattern through the light transmission layer using an objective lens having a numerical aperture NA of 0.85, and 2T to 8T in the 1,7RLL modulation method. Random signals were recorded by randomly combining recording marks having lengths.

  Here, when a random signal is recorded on each sample, the recording power Pw of the laser beam is set to 1.0 mW, the base power Pb is set to 0.5 mW, and the reproduction power Pr is set to 0.7 mW. did.

  Next, the optical recording medium samples # 1 to # 3 and the optical recording medium comparison samples # 1 to # 3 are set in the above-described optical recording medium evaluation apparatus, and under the same conditions as in the case where a random signal is recorded, The random signal recorded in the sample was reproduced, and the symbol error rate (SER) of the reproduced signal was measured.

As a result, in the optical recording medium samples # 1 to # 3, the SER is 6 × 10 ⁻⁵ or less over the entire portion where the random signal is recorded, and the SER characteristic (2 × 10 ⁵⁾ normally required for the optical recording medium. ^In the optical recording medium comparative samples # 1 and # 2, the portion where the random signal was recorded at the location where the bubble was present, whereas the data recording / reproducing characteristics were extremely excellent. SER greatly exceeds 2 × 10 ⁻⁴ and the data recording / reproducing characteristics are remarkably deteriorated. In the optical recording medium comparison sample # 3, the portion where the random signal was recorded at the location where the bubble was present Overall, it was found that the SER exceeded 2 × 10 ⁻⁴ and the data recording / reproducing characteristics were deteriorated.

  The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the invention described in the claims, and these are also included in the scope of the present invention. Needless to say.

  For example, in the above-described embodiment, the ultraviolet curable resin composition that does not generate bubbles when left on the information layer 20 formed on the support substrate 11 in an environment where the pressure is −70 kPaG or less for 5 minutes. An object is applied by spin coating, and the formed resin layer is formed as a light transmitting layer 16 constituting a light incident surface 16a on which a laser beam is incident by one surface of the resin layer. However, it is not always necessary to form the light transmitting layer 16 constituting the light incident surface 16a on which the laser beam is incident on one of the surfaces, and the pressure is −70 kPaG or less on the information layer. In addition, an ultraviolet curable resin composition that does not generate bubbles when allowed to stand for 5 minutes is applied by a spin coating method to form a resin layer. In addition, a resin film formed of a light-transmitting material may be bonded to the information layer via the resin layer, and the light transmission layer may be formed by the resin layer and the resin film. .

  In the above embodiment, the optical recording medium 10 includes one information layer including the first recording film 14a and the second recording film 14b formed of an inorganic material. It is not always necessary to provide the information layer, and the optical recording medium may include a plurality of information layers stacked via a transparent intermediate layer. In this case, an ultraviolet curable resin composition that does not generate bubbles when left on an information layer formed on a support substrate for 5 minutes in an environment having a pressure of −70 kPaG or less is spin-coated. A resin layer that functions as a transparent intermediate layer is formed by coating by a method, and at least another information layer is formed on the resin layer. The transparent intermediate layer thus formed is formed between the two information layers and has a function of separating the two information layers with a sufficient physical and optical distance. In addition, when the optical recording medium includes two or more information layers, the light incident surface on which the laser beam is incident on the surface of the information layer farthest from the support substrate other than the transparent intermediate layer. A resin layer that functions as a light-transmitting layer that constitutes the substrate may be formed, and further, a resin molded by a light-transmitting material through a resin layer formed on the surface of the information layer farthest from the support substrate A film may be bonded to the information layer, and a light transmission layer may be formed by the resin layer and the resin film.

  Further, in the above embodiment, the optical recording medium 10 includes the write-once information layer 12 including the first recording film 14a and the second recording film 14b formed of an inorganic material. However, it is not always necessary to include a write-once information layer including a first recording film and a second recording film formed of an inorganic material, and the information layer includes one or two layers including an organic dye. It may be configured as a write-once type information layer including the above recording film, or may be configured as a read-only type (ROM type) information layer including the surface of the support substrate on which the prepits are formed. Moreover, it may be configured as a rewritable information layer including a recording film including a phase change material.

  In the above embodiment, the light transmission layer 16 is formed by applying an ultraviolet curable resin composition that has been degassed in advance by a spin coating method. It is not always necessary to apply the formed UV curable resin composition by spin coating, and the UV curable resin composition in which the light transmission layer has been previously deaerated is applied to the slot coating method. It may be formed by coating by another coating method such as.

  Furthermore, in the said embodiment, although the light transmission layer 16 apply | coats the ultraviolet curable resin composition by which the deaeration process was carried out previously by spin coating method, a light transmission layer is previously deaerated process. It is not always necessary to apply the formed UV curable resin composition by spin coating, and the light transmission layer has the property of hardly dissolving air or the like, and the pressure is −70 kPaG or less. A resin composition that does not generate bubbles when left in an environment for 5 minutes may be applied by spin coating.

  Furthermore, in the above-described embodiment, the ultraviolet curable resin composition that does not generate bubbles when left under an environment where the pressure is −70 kPaG or less for 5 minutes is degassed after being prepared, It is not always necessary that the resin composition is degassed after the resin composition is prepared, and the resin composition may be prepared after each component constituting the resin composition is degassed.

  Furthermore, in the above embodiment, the ultraviolet curable resin composition is degassed once, but the resin composition is not necessarily degassed once, and the resin composition is not less than twice. Deaeration treatment may be performed.

  Further, in the above embodiment, the ultraviolet curable resin composition is applied on the information layer 20 formed on the support substrate 11 by a spin coating method to form a coating film, and is applied in the air. The film is irradiated with ultraviolet rays to cure the ultraviolet curable resin composition, and the light transmission layer 16 is formed on the information layer 20. The ultraviolet curable resin composition is spin-coated on the information layer. It is not necessary to apply a coating method to form a coating film, and to irradiate the coating film with ultraviolet rays in the air. The UV curable resin composition is formed on the information layer formed on the support substrate. An object is applied by spin coating to form a coating film, and the coating film is irradiated with ultraviolet rays in an inert gas atmosphere to cure the ultraviolet curable resin composition, and light is applied to the information layer. A transmission layer may be formed.

  Moreover, in the said embodiment, although the support substrate 11 is produced by injection molding using a stamper, you may produce a support substrate by other methods, such as 2P method.

FIG. 1 is a schematic perspective view with a part cut away of an optical recording medium manufactured by an optical recording medium manufacturing method according to a preferred embodiment of the present invention. FIG. 2 is a schematic enlarged sectional view of a portion indicated by A in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Optical recording medium 11 Support substrate 12 Reflective film 13 Second dielectric film 14a First recording film 14b Second recording film 15 First dielectric film 16 Light transmission layer 20 Information layer

Claims (4)

On the information layer formed on the support substrate, a resin composition is formed by applying a resin composition that does not generate bubbles when left in an environment of a pressure of −70 kPaG or less for 5 minutes. An optical recording medium manufacturing method characterized by the above. 2. The method of manufacturing an optical recording medium according to claim 1, wherein the resin layer is formed by one surface thereof as a light transmission layer constituting a light incident surface on which a laser beam is incident. Furthermore, a resin film formed of a light-transmitting material is bonded to the information layer through the resin layer formed on the information layer, and the resin layer and the resin film are included. The method of manufacturing an optical recording medium according to claim 1, wherein a light transmission layer is formed. The method for producing an optical recording medium according to claim 1, further comprising forming at least one information layer on the resin layer.

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