JP2007323769A - Manufacturing method of optical recording medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To manufacture a multilayered optical recording medium of high quality with satisfactory productivity at low costs. <P>SOLUTION: In a manufacturing method of the multilayered optical recording medium wherein a UV curing resin is supplied on a reflection layer or a recording layer of a supporting base material having a rugged pattern (a signal pattern) and the reflection layer or the recording layer formed on the rugged pattern, a transparent stamper is placed on the UV curing resin, the UV curing resin is cured by irradiation with UV via the transparent stamper, the transparent stamper is peeled to form a rugged pattern formed layer to which a rugged pattern of the transparent stamper is transferred and which consists of a cured UV curing resin and a reflection layer or a recording layer is formed on the rugged pattern formed layer, a thermoplastic resin sheet 5 which is formed by superposing the thermoplastic resin sheet 5 and a metal stamper 3 and applying heat and pressure and to which the rugged pattern of the metal stamper 3 is transferred is used as the transparent stamper. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for producing an optical recording medium having a multilayer structure in which a plurality of reflective layers or recording layers are formed on a supporting substrate.

  In recent years, optical recording media are being applied as media for recording various types of information in the fields of computers, audiovisuals, and the like. With the spread of mobile computers and the diversification of information, the demand for small and large capacity optical recording media is increasing.

  An optical recording medium records or reproduces information by light. On the support substrate of the optical recording medium, for example, pits and pregrooves for obtaining signals such as tracking servo signals or fine uneven patterns (signal patterns) for obtaining signals such as data information are formed. Then, a single-plate optical recording medium in which a recording layer or a reflective layer is formed on the support substrate and an organic protective layer is further formed thereon, or the recording layers or reflections of the two support substrates. There is an optical recording medium having a structure in which layer surfaces are bonded to face each other.

  The above-described optical recording medium having a single plate configuration or a bonded configuration has only one recording layer or reflection layer on one supporting base material surface. On the other hand, in order to increase the recording density, an optical recording medium having a multilayer structure having a plurality of recording layers and the like on one support base material surface has been proposed. In this multilayer optical recording medium, for example, a reflective layer or a recording layer is formed on a support substrate on which a fine uneven pattern (signal pattern) is formed, and an uneven pattern (signal pattern) is formed on the recording layer. A layer is formed, and a reflective layer or a recording layer is further formed on the concavo-convex pattern forming layer. Such a recording layer and a concavo-convex pattern forming layer are repeatedly formed as necessary, and finally an organic protective layer is formed. Thereby, an optical recording medium having a plurality of recording layers on one supporting base material surface is obtained.

  Incident light for recording, reproducing, and erasing information can be applied from the support substrate surface side or the organic protective layer surface side. Both surfaces can also be used. However, it is easier to reduce the thickness of the supporting base material from the organic protective layer surface side, and it is possible to increase the NA (aperture) of the objective lens of the pickup, which is advantageous in achieving higher density. It is known that

  For example, the following methods are known as a method for producing a multilayer-structured optical recording medium. First, an uneven pattern and a reflective layer or a recording layer are formed on a support substrate. Next, (1) an ultraviolet curable resin is applied on the reflective layer or the recording layer. Next, (2) a transparent stamper is overlaid on the ultraviolet curable resin. Next, (3) by irradiating with ultraviolet rays through a transparent stamper, the ultraviolet curable resin is cured to produce a concavo-convex pattern forming layer. Next, (4) the transparent stamper is peeled off. Next, (5) a reflective layer or a recording layer is formed on the concavo-convex pattern. Then, the steps (1) to (5) are repeated as necessary, and finally an organic protective layer is formed on the reflective layer or the recording layer.

  The above lamination method is an application of the conventional 2P method (Photo Polymer method). However, in the conventional 2P method, an ultraviolet curable resin and a transparent support substrate are superimposed on a metal stamper, and the ultraviolet curable resin is cured by irradiating ultraviolet rays from the transparent support substrate side. When ultraviolet light is irradiated from the support base, the ultraviolet energy is attenuated, and the ultraviolet curable resin cannot be sufficiently cured. In particular, when a plurality of reflective layers or recording layers are laminated, this is remarkable, and there is a problem that the resin of the supporting base material is deteriorated by ultraviolet rays by irradiating excessive ultraviolet rays. For this reason, in the above method, a transparent stamper is used and ultraviolet rays are irradiated from the transparent stamper side. As the transparent stamper, it is considered that a resin stamper is used because it is easily broken by a glass stamper. However, there is a problem that the ultraviolet curable resin remains in the resin stamper due to deterioration of the resin due to ultraviolet rays. In addition, when the transparent stamper is repeatedly used, the uneven pattern or the shape change of the transparent stamper itself occurs. Accordingly, it is difficult to reuse in terms of quality and productivity, and a transparent stamper is disposable every time the concave / convex pattern is formed, and there is a problem that costs increase.

  The manufacturing method of the transparent stamper described above is described in Patent Document 1 and Patent Document 2, for example.

  In Patent Document 1, a transparent stamper is produced by injection molding or a casting method using a photocurable resin. In the injection molding method, although a high-quality transparent stamper can be easily produced, molding a plurality of transparent stampers at one time has a transferability problem and has not been realized. In addition, if the thickness of the transparent stamper in the injection molding is reduced, transfer defects are likely to occur. Therefore, a thickness of about 0.6 mm or more is required. For this reason, in the injection molding method, it is possible to reduce the cost by using a low-cost material whose optical characteristics are inferior to the material for the substrate that becomes the light incident surface, but it is greatly increased from the viewpoint of production tact and material usage. Cost reduction is not expected.

  On the other hand, the method using a photocurable resin is the conventional 2P method, and the productivity is poor as compared with an injection molding method or the like. Therefore, it is not practical in a multilayer configuration optical recording medium that requires a large number of transparent stampers.

  In patent document 2, in extrusion molding, a transparent stamper is manufactured by attaching a flat stamper to a roller and allowing the roller to pass through. In this molding method, a transparent stamper can be continuously produced. However, since the flat stamper is warped in a roll shape, the shape cannot be accurately transferred when the uneven pattern is a dense high-density pattern. Further, in order to maintain the transferability of the uneven pattern, it is necessary to slow down the extrusion speed to some extent, which causes a problem in productivity.

  That is, the conventional transparent stamper manufacturing method as described above cannot manufacture a high-density concavo-convex pattern with high quality and low cost. In addition, the resin material of the ultraviolet curable resin and the transparent stamper has higher adhesion than the metal stamper, and is difficult to peel off. Therefore, it is considered to form a metal thin film on the uneven pattern surface of the transparent stamper, or to use a polyolefin resin or a norbornene resin. However, the formation of the metal thin film has a problem of ultraviolet energy attenuation. In addition, since materials such as polyolefin resin and norbornene resin are expensive, the conventional method using a large amount of molding material is extremely expensive.

Furthermore, when the conventional transparent stamper as described above is used, it is necessary to increase the thickness of the stamper from the viewpoint of transferability. From the viewpoint of cost, it is necessary to suppress the amount of molding material used as much as possible. Therefore, a conventional transparent stamper obtained by an injection molding method or a casting method has a size comparable to that of the supporting base material. This makes it difficult to peel the transparent stamper from the support substrate. In general, when the thickness of the transparent stamper increases, the resistance to external force increases due to the elasticity of the resin, making it difficult to deform it. Therefore, when the transparent stamper is peeled from the interface of the ultraviolet curable resin, a large force is required in the step of obtaining the starting point that causes the peeling and the step of expanding the peeling region from the starting point. As a result, the facilities become complicated and large. In particular, when the supporting substrate and the transparent stamper have the same size, this is remarkable, and it is difficult to obtain the starting point of peeling.
Japanese Utility Model Publication No. 5-59615 JP-A-5-47048

  An object of the present invention is to manufacture a transparent stamper used in a manufacturing process of a multilayer structure optical recording medium at a high quality and at a low cost, and to easily peel off the transparent stamper in the forming process of each layer using the transparent stamper. Is to provide.

  It is a further object of the present invention to provide a method capable of producing a high-quality multi-layered optical recording medium at low cost and high productivity.

In the present invention, an ultraviolet curable resin is supplied onto the reflective layer or the recording layer of a support substrate on which a concavo-convex pattern and a reflective layer or a recording layer are formed, and a transparent stamper is provided on the ultraviolet curable resin. And curing the ultraviolet curable resin by irradiating ultraviolet rays through the transparent stamper, peeling the transparent stamper, and transferring the concavo-convex pattern of the transparent stamper. In the method for producing a multilayer-structured optical recording medium, a concavo-convex pattern forming layer is formed, and a reflective layer or a recording layer is further formed on the concavo-convex pattern forming layer.
A method for producing an optical recording medium, comprising using a thermoplastic resin sheet formed by transferring a concavo-convex pattern of a stamper by applying heat and pressure by superposing a thermoplastic resin sheet and a stamper as the transparent stamper. .

  Furthermore, in the method for producing an optical recording medium of the present invention, it is preferable that the outer diameter of the transparent stamper is larger than the outer diameter of the support substrate.

  Furthermore, in the method for producing an optical recording medium of the present invention, a thermoplastic resin sheet on which a concavo-convex pattern of the plurality of stampers is simultaneously transferred and formed by superimposing a thermoplastic resin sheet and a plurality of stampers and applying heat and pressure. It is preferable to use as a plurality of transparent stampers.

  Furthermore, in the method for producing an optical recording medium of the present invention, after placing the transparent stamper on the ultraviolet curable resin, the transparent plate member is placed on the transparent stamper to spread the ultraviolet curable resin, It is preferable to cure the ultraviolet curable resin by irradiating ultraviolet rays through the transparent plate member and the transparent stamper.

  The present invention superimposes a thermoplastic resin sheet and a stamper, and applies heat and pressure to transfer a stamper concave / convex pattern (signal pattern) to the thermoplastic resin sheet, and the thermoplastic resin sheet on which the concave / convex pattern is formed Is used as a transparent stamper. As a result, a thin sheet-like transparent stamper, which has been difficult with the conventional injection molding method or the like, can be easily produced with high accuracy, and the material cost can be greatly reduced. Moreover, it becomes easy to make the shape of the transparent stamper larger than the outer diameter of the support base material. As a result, the outer peripheral portion outside the effective area of the transparent stamper can be held and easily peeled from the support substrate. Furthermore, it is possible to produce a plurality of transparent stampers at the same time using a plurality of stampers, which has been difficult with conventional injection molding, thereby improving productivity.

  Therefore, according to the present invention, a low-cost and high-quality transparent stamper can be manufactured with high productivity, and a concavo-convex pattern (signal pattern) can be manufactured with high quality and easily at low cost in a multilayer optical recording medium.

  In the present invention, the concavo-convex pattern is a concavo-convex pattern that functions as a signal pattern of an optical recording medium. For example, a fine pattern for obtaining a signal such as a pit, pregroove, or data information for obtaining a signal such as a tracking servo signal. It is an uneven pattern.

  1 and 2 schematically show a method for producing a transparent stamper in the method for producing a multilayer-structured optical recording medium of the present invention. FIG. 1 is a perspective view thereof, and FIG. 2 is a sectional view thereof. . With reference to these FIG.1 and FIG.2, embodiment of the manufacturing method of a transparent stamper is described below.

  First, the metal stamper 1 is fixed on the mold 3 by the metal stamper fixing jig 2. Next, the thermoplastic resin sheet 5 is overlaid on the metal stamper 1. Next, the upper movable mold 4 is lowered, and heating and pressurization are performed to transfer the uneven pattern of the metal stamper 1 to the thermoplastic resin sheet 5. Next, the temperature of the thermoplastic resin sheet 5 is lowered by cooling the mold 3 and the movable mold 4 as necessary. Next, the movable mold 4 is raised, and the thermoplastic resin sheet 5 is further peeled from the metal stamper 1. The uneven pattern of the metal stamper 1 is transferred to the thermoplastic resin sheet 5 thus obtained, and this can be used as a transparent stamper.

  As described above, in the present invention, the thermoplastic resin sheet and the stamper are superposed and heated and pressed to produce a transparent stamper. Therefore, it becomes possible to make the film thickness of the softened thermoplastic resin sheet uniform by pressing horizontally when transferring the uneven pattern with heat and pressure. As a result, it is possible to use a generally available inexpensive resin sheet without requiring high-precision film thickness uniformity of the material, and to significantly reduce the material cost.

  The transparent stamper thus produced can be used in the form of a sheet, and can be used after being processed into a predetermined size as required. When processing the shape, it is desirable to process it into a shape larger than the supporting base material. The suitable shape should just have a part which can grasp the outer peripheral part outside the effective area | region of a transparent stamper, when peeling a transparent stamper from an uneven | corrugated pattern formation layer. Here, “outside the effective region” means a portion other than the region of the concavo-convex pattern (signal pattern) to be transferred. Specific examples of the shape of the transparent stamper include a circle and a polygon. The shape processing method is not particularly limited. A typical example of the shape processing method is a method of shape processing with a punching press. Other methods such as shape processing by laser processing or cutting by mechanical cutting are also possible.

  The thermoplastic resin sheet may be any sheet that can transfer and form the concave / convex pattern of the metal stamper with heat and pressure. A material having a higher ultraviolet transmittance is better, but the material is not limited to an optical recording medium material having excellent optical properties such as birefringence. Specific examples of the thermoplastic resin constituting the sheet include various resins such as polycarbonate resin, acrylic resin, polyolefin resin (polyethylene resin, polypropylene resin, etc.), norbornene resin, polystyrene resin, polyethylene terephthalate resin, and vinyl chloride resin. It is done. A sheet formed by laminating a plurality of resins can also be used. From the viewpoint of releasability from the ultraviolet curable resin, polyolefin resin and norbornene resin are preferable.

  The thermoplastic resin sheet should just be a sheet | seat in which the surface which forms an uneven | corrugated pattern is comprised with the thermoplastic resin at least. Therefore, a sheet in which a thermoplastic resin layer is laminated on a material other than the thermoplastic resin can also be used. It is also possible to recycle used transparent stampers.

  The thickness of the thermoplastic resin sheet is not particularly limited as long as it is optimized to a thickness that can transfer the uneven pattern shape of the metal stamper and does not hinder handling. In particular, from the viewpoint of material cost and transferability, the thickness is preferably in the range of 0.01 mm to 0.3 mm.

  Specific molding conditions in the concave / convex pattern transfer process shown in FIGS. 1 and 2 may be optimized according to the type of thermoplastic resin constituting the sheet, the sheet thickness, the concave / convex pattern, and the like, and are not particularly limited. In particular, the transfer is performed by heating to a temperature at or above the glass transition point or softening point of the thermoplastic resin, then cooling to a temperature lower than the glass transition point and the softening point, and the metal stamper and the thermoplastic resin sheet are peeled off. It is desirable. Further, when the metal stamper and the thermoplastic resin sheet are overlapped, it is desirable to overlap in a vacuum for the purpose of avoiding air and dust. In addition, the alignment of the two in this superposition does not require highly accurate alignment, and at least the effective area of the metal stamper only needs to be covered with the thermoplastic resin sheet, and no special process or mechanism is required. .

  In FIG. 1, six metal stampers 1 are installed on the mold 3, but the number of stampers installed on the mold 3 is not particularly limited in the present invention. The number of stampers may be determined as necessary. For example, only one stamper may be installed and used.

  Although the metal stamper 1 is used in FIGS. 1 and 2, the type of the stamper installed on the mold 3 is not particularly limited in the present invention. The type of the stamper may be determined as necessary, and a stamper made of, for example, glass or ceramic can be used in addition to the metal stamper. However, a metal stamper is preferable from the viewpoint of durability against pressure and heating. Specific examples thereof include a stamper made of a known metal material such as Ni, Ti, or an alloy thereof.

  Next, a method for producing a multilayer optical recording medium using the transparent stamper produced as described above will be described. FIG. 3 is a view schematically showing a layer forming process using a transparent stamper in the method for producing a multilayer optical recording medium of the present invention.

  First, a support substrate 6 having a concavo-convex pattern (not shown) and a reflective layer or recording layer 7 formed on the concavo-convex pattern is prepared [FIG. 3A]. The formation of the concavo-convex pattern on the support substrate 6 may be formed by a known technique such as injection molding or 2P method, and is not particularly limited. In the present invention, the recording layer may be a recording layer composed of a plurality of films such as a recording film and a dielectric film, or may be a recording layer composed of a single layer film. Further, a reflection layer for giving a signal for ROM may be formed.

  Next, the ultraviolet curable resin 8 is supplied onto the reflective layer or the recording layer 7, and the transparent stamper 12 is further superimposed thereon [FIG. 3B]. It is preferable to adjust the relative positional relationship between the transparent stamper 12 and the support base 6 after or simultaneously with the overlapping. The purpose of this positional relationship adjustment is to match the relative positional relationship between the concave / convex pattern of the transparent stamper 12 and the concave / convex pattern of the support base 6. Further, it is preferable to place a transparent plate-like member (for example, quartz glass polished on both sides) with flat surfaces on the transparent stamper 12 to spread the ultraviolet curable resin 8 over the entire surface. If a transparent plate member is used, even if the transparent stamper 12 is thin, its flatness can be corrected, and a highly flat uneven pattern forming layer 8 ′ can be formed.

  In the example shown in FIG. 3, the ultraviolet curable resin 8 is spread over the entire surface, but the present invention is not limited to this. For example, a region where the ultraviolet curable resin 8 is not formed can be provided on the outer peripheral portion of the support base 6 (particularly, in the case of a disc shape, the outer peripheral portion and the inner peripheral portion). In this case, the peelability between the transparent stamper 12 and the ultraviolet curable resin 8 is improved by the amount of no protruding portion.

  Next, ultraviolet rays are irradiated through the transparent stamper 12 to cure the ultraviolet curable resin 8 to form an uneven pattern forming layer (signal pattern forming layer) 8 ′. Here, when a transparent plate-like member is placed on the transparent stamper 12, ultraviolet rays are irradiated through the transparent stamper 12 and the transparent plate-like member. In the example shown here, the outer diameter of the transparent stamper 12 is larger than the outer diameter of the support base 6. Therefore, the transparent stamper 12 may be lifted by grasping the outer peripheral portion of the transparent stamper 12 (portion other than the effective area of the stamper). By such a process, the concave / convex pattern of the transparent stamper 12 is transferred and formed on the cured ultraviolet curable resin 8, which becomes the concave / convex pattern forming layer 8 ′.

  The surface of the supporting substrate 6 that does not have the concavo-convex pattern is held by a vacuum suction mechanism or the like, and the transparent stamper 12 is pulled up, thereby peeling the concavo-convex pattern forming layer 8 ′ (cured ultraviolet curable resin 8) and the transparent stamper 12. To do. Thereby, uneven | corrugated pattern formation layer 8 'is obtained. Here, the concavo-convex pattern forming layer 8 ′ is a role of imparting a desired concavo-convex pattern (signal pattern) to the reflective layer or recording layer formed thereon, that is, a support base different from the support substrate 6 described above. It is a layer that functions as a material.

  Next, a reflective layer or a recording layer 9 is formed on the uneven pattern forming layer 8 ′ [FIG. 3C]. Next, a transparent organic protective layer 10 serving as a light incident surface is formed on the reflective layer or the recording layer 9 to obtain a multi-layered optical recording medium [FIG. 3D].

  Although FIG. 3 shows an example of manufacturing an optical recording medium having a two-layer structure, the present invention is not limited to this. For example, if a concavo-convex pattern forming layer is further formed on the reflective layer or the recording layer 9 and a further reflective layer or recording layer is formed on the reflective layer or the recording layer 9 and this process is repeated as necessary, light having a multilayer structure of three or more layers is formed. A recording medium can also be manufactured.

  The ultraviolet curable resin 8 is not particularly limited as long as it is a resin that does not optically interfere with recording, reproduction, and erasing of the optical recording medium. However, in recent years, the wavelength of light used for recording / reproducing / erasing has been shortened to 785 nm for CDs and 660 nm for DVDs, and a wavelength of 405 nm has been studied for Blu-ray Discs. Therefore, a resin having little absorption, reflection and birefringence in these wavelength regions is desirable. Specifically, for example, an acrylic resin, an epoxy resin, a urethane resin, a phenol resin, and various modified resins can be used, and among these, those that have low absorption in the above wavelength region are preferable. Further, the ultraviolet curable resin 8 is usually cured by being mixed with a photopolymerization initiator and being irradiated with ultraviolet rays. Therefore, the absorption region of the photopolymerization initiator is preferably different from the wavelength region of light used for recording / reproducing / erasing of the optical recording medium. Further, for example, a dry photopolymer formed into a sheet shape in an uncured or semi-cured state can be used as the ultraviolet curable resin 8.

  The thickness of the concavo-convex pattern forming layer 8 ′ (ultraviolet curable resin 8 after curing) is not particularly limited. Usually, a layer thickness of about 1 μm to 300 μm is preferable, but an optimum film thickness may be selected depending on the number of films constituting the recording layer and the dynamic range of the spherical aberration correction mechanism. In addition, an adhesive or a sheet base material can be provided between the reflective layer or the recording layer and the concavo-convex pattern forming layer 8 ′ in order to adjust the interlayer distance between the reflective layers or the recording layers as necessary.

  The method for forming the reflective layer or recording layers 7 and 9 is not particularly limited, and examples thereof include sputtering, vapor deposition, CVD, dipping coating, and spin coating. Specifically, any method that is optimal for each production process, production apparatus, and optical recording medium to be produced may be used.

  The material constituting the reflective layer or the recording layers 7 and 9 is not particularly limited. For example, a known material can be used as the material of the optical recording layer. Specific examples thereof include at least one of materials such as Te, In, Ga, Sb, Se, Pb, Ag, Au, As, Co, Ni, Mo, W, Pd, Ti, Bi, Zn, and Si. The alloy which consists of the above is mentioned. In addition, a known material can be used as the material of the magneto-optical recording layer. Specific examples thereof include alloys composed of at least one of materials such as Tb, Fe, Co, Cr, Gd, Dy, Nd, Sm, Ce, and Ho, and rare earth-transition metal alloys. Moreover, a well-known material can also be used as a material of a light reflection layer. Specific examples thereof include Al and Al alloy, Si and SiN, Ag and Ag alloy. Furthermore, organic dye materials such as cyanine materials, phthalocyanine materials, and azo materials can also be used as the optical recording layer.

  The thickness of the reflective layer or recording layers 7 and 9 may be set as necessary. When recording, reproducing or erasing light is incident on the light incident surface of the optical recording medium, attenuation of the light occurs in each of the reflective layers or recording layers 7 and 9 from the light incident surface side. Accordingly, the transmittance of each layer at the wavelength of the light is preferably higher as the layer is closer to the incident surface side. For example, when the transmittance of the reflective layer or recording layer 7 is L0 and the transmittance of the reflective layer or recording layer 9 is L1, the film may be formed so as to satisfy the following relationship.

L0 <L1
In order to form a film so that the transmittance is in the above relationship, for example, film formation conditions such as film formation pressure, gas flow rate, power, and film thickness may be adjusted as appropriate.

  Further, it is preferable to adjust the composition and film thickness of each reflective layer or recording layer so as not to hinder the recording / reproducing / erasing of each layer. By optimizing the composition, film thickness, film forming conditions, etc. for each reflective layer or recording layer 7, a reflective layer or recording layer having an arbitrary transmittance and reflectance can be formed. In the present invention, a known one suitable for a desired optical recording medium may be used, and there is no particular limitation.

  When the multi-layered optical recording medium is formed with the concavo-convex pattern forming layer 8 ′ (cured ultraviolet curable resin 8), the ultraviolet curable resin 8 has an outer peripheral portion (in the case of a disk shape or the like, an inner peripheral portion and an inner May protrude from the periphery. As countermeasures, for example, a method of preventing the protrusion by hardening the outer peripheral portion in advance, a method of wiping the protrusion in an uncured state, a method of removing the protrusion by shaping the optical recording medium after manufacture and so on. The shape processing method for removing the protruding portion is not particularly limited. A typical method is shape processing by a punching press. In addition, for example, shape processing by cutting by laser processing or mechanical cutting is also possible.

  In addition, if the portion where the UV curable resin 8 protrudes from the support base 6 rises along the outer peripheral edge of the support base and the film thickness increases, the adhesion with the transparent stamper 12 at that portion increases. To do. In this case, when the transparent stamper 12 is pulled up, only the protruding portion remains on the transparent stamper 12 side, and an optical recording medium from which the protruding portion is removed is obtained.

  Further, when the optical recording medium has a disk shape, if the eccentricity of each formed layer is large, troubles such as the tracking servo coming off occur. Therefore, when the transparent stamper 12 and the support base 6 are overlapped, a center alignment (hereinafter referred to as “centering”) process is usually performed together. The center portion of the transparent stamper 12 is cut at the time of forming the concavo-convex pattern, or cut after the concavo-convex pattern is formed, so that the center portion of the support base 6 and the center portion of the transparent stamper 12 are mechanically adjusted and easily centered. You can also. Specifically, a known centering process in 2P method or the like can be used. Also, without providing an opening in the center, a position correction mechanism is provided that reads position information such as the uneven pattern of the support base material and the transparent stamper and adjusts the position of the support base material or the transparent stamper to perform centering. Is also possible. By providing this position correction mechanism, highly accurate centering can be performed.

  The multilayer structured optical recording medium manufactured as described above records, reproduces and erases information by light. The light incident surface is not particularly limited, but is preferably on the organic protective layer surface side, that is, the side opposite to the supporting base material.

<Example>
According to the steps shown in FIGS. 1 and 2, a transparent stamper was produced as follows.

  First, the metal stamper 1 was fixed on the mold 3 with the metal stamper fixing jig 2. Next, a thermoplastic resin sheet 5 made of polycarbonate resin having a thickness of 0.1 mm was overlaid on the metal stamper 1. Specifically, the thermoplastic resin sheet 5 was brought into close contact with the metal stamper 1 by gradually overlapping with a roller so that air bubbles would not be mixed in between. Next, the upper movable mold 4 was lowered in vacuum to bring the movable mold 4 into close contact with the thermoplastic resin sheet 5. Here, by mixing in a vacuum, bubbles could be prevented from being mixed. Further, the mold 3 and the movable mold 4 were heated to 150 ° C., and the movable mold 4 was pressed downward at a pressure of 10 MPa and held for 3 minutes. Next, the mold 3 and the movable mold 4 were cooled to 40 ° C. Next, the movable mold 4 was raised to hold the outer peripheral end of the thermoplastic resin sheet 5 and peeled from the metal stamper 1. The resulting thermoplastic resin sheet 5 has a concavo-convex pattern (signal pattern) of the metal stamper 1 transferred thereto, and this can be used as the transparent stamper 12 (FIG. 3). The transparent stamper has a shape that does not have a center hole, and the outer diameter thereof is larger than the outer diameter of the support substrate.

  In the above process, the glass transition point of the polycarbonate resin constituting the thermoplastic resin sheet 5 is 140 ° C., and the thermal deformation temperature is about 120 ° C. Moreover, the temperature of the thermoplastic resin sheet 5 when the mold was opened was about 40 ° C. to about 50 ° C.

  Next, using the transparent stamper produced by the above method, a multilayer structured optical recording medium (multilayer structured optical disk) was produced as follows according to the steps shown in FIG.

  First, as the support base 6, a disk-shaped substrate made of polycarbonate resin having a thickness of 1.1 mm, an outer diameter of 120 mm, and an inner diameter of 15 mm formed with an uneven pattern (not shown) by injection molding was prepared. A reflective layer 7 was formed on the concavo-convex pattern surface of the support substrate 6 by a film forming apparatus [FIG. Specifically, SiN was deposited to a thickness of 10 nm by sputtering, and this was used as the reflective layer 7.

  Next, an ultraviolet curable resin 8 (product name INC-118, manufactured by Nippon Kayaku Co., Ltd.) was applied on the reflective layer 7, and a transparent stamper 12 was further superimposed thereon [FIG. 3 (B)].

  Next, the support base 6 is held by a vacuum suction mechanism, and the position of the transparent stamper 12 is adjusted by the concave / convex pattern reading mechanism and the position adjustment mechanism so that the concave / convex pattern of the support base 6 matches the concave / convex pattern of the transparent stamper. It was adjusted. Next, quartz glass having a uniform plate thickness and polished on both sides was placed on the transparent stamper 12, and the ultraviolet curable resin 8 was spread over the entire surface. Next, ultraviolet rays were irradiated from the quartz glass side to cure the ultraviolet curable resin 8. In addition, the ultraviolet curable resin 8 that protruded from the outer peripheral portion of the support base 6 was thickened in a shape that swelled along the outer peripheral end portion.

  Next, the quartz glass was removed, and the outer peripheral end portion outside the effective area of the transparent stamper 12 was grasped and pulled upward while the support base 6 was held by the vacuum suction mechanism. In this way, first, the separation starting point of the interface between the transparent stamper 12 and the ultraviolet curable resin 8 was obtained at the outer peripheral portion of the support base 6. Further, the transparent stamper 12 was lifted upward to complete the peeling of the transparent stamper 12. Here, the portion of the ultraviolet curable resin 8 that protruded from the outer peripheral end was adhered to the transparent stamper 12 side and was removed together with the peeling of the transparent stamper 12.

  As described above, an ultraviolet curable resin 8 (after curing) on which the uneven pattern of the transparent stamper 12 was transferred and formed was obtained. This is the concavo-convex pattern forming layer 8 ′. The film thickness of the uneven pattern forming layer 8 ′ was 15 μm on average, and the film thickness variation was within ± 1 μm on the entire surface.

  Next, a reflective layer 9 was formed on the concave / convex pattern forming layer 8 ′ (ultraviolet curable resin 8 after curing) by a film forming apparatus [FIG. 3 (C)]. Specifically, SiN was formed to a thickness of 7 nm by sputtering, and this was used as the reflective layer 9. The film forming conditions for both layers were adjusted as appropriate so that the transmittance L1 of the reflective layer 9 was greater than the transmittance L0 of the reflective layer 7.

  Next, an ultraviolet curable resin (manufactured by Nippon Kayaku: INC-118) was spin-coated on the reflective layer 9, and the entire coating film was cured by a UV curing device to form an organic protective layer 10 having a thickness of 75 μm. [FIG. 3D]. This organic protective layer 10 becomes a light incident surface. An optical recording medium having a two-layer structure was obtained by the process described above.

  When the recorded information was reproduced from the surface of the organic protective layer 10 of the optical recording medium having the two-layer structure, reproduction was possible on the entire surface without any problem.

  Further, in this embodiment, since the transparent stamper 12 is thin and has an area that can be held outside the effective area, the outer periphery of the transparent stamper 12 is grasped and the transparent stamper is easily deformed, so that it is rolled. It has become possible to wind up. Further, the peeling process, which was difficult with the conventional method, is facilitated, the productivity is remarkably improved, and the production of the transparent stamper is easy, so that the production cost can be greatly reduced.

<Comparative example>
FIG. 4 is a schematic view of a conventional method for producing a multilayer optical recording medium. Since the transparent stamper 11 used in the step shown in FIG. 4 is manufactured by injection molding, the thickness is relatively thick, and the size of the inner and outer diameters is the same as that of the support base 6. The process shown in FIG. 4 is the same as the process shown in FIG. 3 except that such a transparent stamper 11 is used.

  In this comparative example, first, a transparent stamper 11 made of polycarbonate resin having a thickness of 1.1 mm, an outer diameter of 120 mm, and an inner diameter of 15 mm prepared by injection molding was prepared. Then, using this transparent stamper 11, in accordance with the steps shown in FIG. 4, a multilayer structured optical recording medium (multilayer structured optical disc) was manufactured as follows.

  First, the reflective layer 7 was formed in the uneven | corrugated pattern surface of the support base material 6 similarly to the Example [FIG. 4 (A)]. Next, an ultraviolet curable resin 8 was applied on the reflective layer 7 in the same manner as in the example.

  Next, the previously prepared transparent stamper 11 was overlaid on the ultraviolet curable resin 8 [FIG. 4B]. The size of the inner and outer diameters of the transparent stamper 11 is the same as the size of the support base 6 (outer diameter 120 mm, inner diameter 15 mm), and the transparent stamper 12 used in the example is larger. Further, since the transparent stamper 11 is manufactured by injection molding, the thickness is relatively thick (1.1 mm), and the transparent stamper 12 used in the embodiment is thinner.

Next, in the same manner as in the example, the position was adjusted, the quartz glass was placed, the ultraviolet curable resin 8 was spread over the entire surface, the ultraviolet curable resin 8 was cured by ultraviolet irradiation, and the quartz glass was removed.
Next, when the transparent stamper 11 was pulled upward with the support base 6 held by the vacuum suction mechanism, it was difficult to obtain a starting point of peeling at the interface between the transparent stamper 11 and the ultraviolet curable resin 8. Further, after obtaining the starting point, when the peeling region was enlarged, a strong shape restoring force was generated in the transparent stamper 11 itself due to the elasticity of the transparent stamper 11. This is because the transparent stamper 11 is too thick. As a result, the transparent stamper 11 again came into contact with the ultraviolet curable resin 8 with insufficient peeling, and a fine uneven pattern was hit twice, resulting in frequent defects. Further, the ultraviolet curable resin 8 protruded from the outer peripheral portion of the support base 6 and the protruding portion became burrs and generated dust, so that dust defects occurred frequently.

  As described above, the concavo-convex pattern forming layer 8 ′ was formed in the same manner as in the example except that the transparent stamper 11 was used. The film thickness of the uneven pattern forming layer 8 ′ was 15 μm on average, but the film thickness variation on the entire surface was ± 10 μm. This is presumably because the transparent stamper 11 is produced by injection molding, so that the flatness of the surface is inferior to that of the transparent stamper 12 used in the example, and the plate thickness varies.

  Next, a reflective layer 9 is formed on the concave / convex pattern forming layer 8 ′ in the same manner as in the example [FIG. 4C], an organic protective layer 10 is formed [FIG. 4D], and a two-layer structure is formed. An optical recording medium was obtained.

  When the recorded information was reproduced from the surface of the organic protective layer 10 of the two-layer optical recording medium, the tracking servo characteristics were unstable, which hindered reproduction of the recorded information. This is due to the accuracy of the concavo-convex pattern in the reflective layer 9 on the light incident surface side, variations in interlayer distance, and defects.

It is the typical perspective view which showed the preparation processes of the transparent stamper of this invention. It is the schematic cross section which showed the preparation process of the transparent stamper of this invention. It is the model which showed the manufacturing process of the multilayer structure optical recording medium using the transparent stamper of this invention. It is the schematic diagram which showed the manufacturing process of the multilayer structure optical recording medium using the conventional transparent stamper.

Explanation of symbols

1: Metal stamper 2: Metal stamper fixing jig 3: Mold 4: Movable mold 5: Thermoplastic resin sheet 6: Support base material 7: Reflective layer or recording layer (L0)
8: UV curable resin 8 ': Concave and convex pattern forming layer 9: Reflective layer or recording layer (L1)
10: Organic protective layer 11: Conventional transparent stamper 12: Transparent stamper

Claims (4)

An ultraviolet curable resin is supplied onto the reflective layer or the recording layer of the support substrate on which the reflective layer or the recording layer is formed on the concave / convex pattern, and a transparent stamper is placed on the ultraviolet curable resin. Irradiation with ultraviolet rays through the transparent stamper cures the ultraviolet curable resin, peels off the transparent stamper, and the concavo-convex pattern made of the cured ultraviolet curable resin onto which the concavo-convex pattern of the transparent stamper is transferred In the method for producing a multilayer-structured optical recording medium in which a formation layer is formed, and further a reflective layer or a recording layer is formed on the concavo-convex pattern formation layer,
A method for producing an optical recording medium, comprising using a thermoplastic resin sheet formed by transferring a concavo-convex pattern of a stamper by applying heat and pressure by superposing a thermoplastic resin sheet and a stamper as the transparent stamper.   The method for producing an optical recording medium according to claim 1, wherein an outer diameter of the transparent stamper is larger than an outer diameter of the support base material.   3. The thermoplastic resin sheet, in which a thermoplastic resin sheet and a plurality of stampers are overlapped and heat and pressure are applied to transfer the uneven patterns of the plurality of stampers simultaneously, are used as a plurality of transparent stampers. The manufacturing method of the optical recording medium of description.   After placing the transparent stamper on the ultraviolet curable resin, the transparent plate member is placed on the transparent stamper to spread the ultraviolet curable resin, and then the ultraviolet ray is passed through the transparent plate member and the transparent stamper. The method for producing an optical recording medium according to any one of claims 1 to 3, wherein the ultraviolet curable resin is cured by irradiating.

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