JP2007141370A - Optical recording medium and manufacturing method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To inhibit a photocurable resin in an outer peripheral part of a substrate from swelling and wraparounding at/to the outer peripheral part when the photocurable resin is expanded by a spin coating method. <P>SOLUTION: A substrate 1 and an extended part 24 having a plane almost as high as the outer peripheral part of the substrate 1 are rotated to expand the photocurable resin 3a on a first information signal part 2 (Figure 4B), light is emitted to the expanded photocurable resin 3a to half-cure the photocurable resin (Figure 4C) while covering the outer peripheral part of the substrate 1 with a light shielding part 25, the substrate 1 is rotated again to eliminate excessive photocurable resin 3c from the outer peripheral part (Figure 4D), a stamper 27 is pressed on the half-cured photocurable resin 3b, and light is also emitted to the photocurable resin 3b and 3c to completely cure the photocurable resin 3b and 3c. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an optical recording medium and a method for manufacturing the same. Specifically, the present invention relates to an optical recording medium including a light-transmitting resin layer and a manufacturing method thereof.

  In recent years, an increase in the capacity of an optical recording medium has been demanded as the quality of moving images and still images increases. In order to meet this demand, it has been proposed to reduce the spot size by reducing the wavelength of the laser light and increasing the NA of the objective lens. For example, in a Blu-ray disc (Blu-ray Disc (registered trademark), hereinafter referred to as BD), blue-violet laser light is condensed by an objective lens having a high NA (for example, 0.85), and the condensed laser light is collected. A recording capacity of about 25 GB is realized by irradiating the reflective film or the recording layer from the light transmission layer side.

  Further, in recent years, it has been studied to further increase the capacity by increasing the number of recording films. For example, in a BD (Dual Layer BD) having two reflective films or recording films on one side, a recording capacity of about 50 GB can be realized by forming the recording film into two layers.

  By the way, the use of a spin coating method has been studied for the formation of the above-described light transmission layer and intermediate layer. However, when the light transmission layer or the intermediate layer is formed by the spin coating method, the ultraviolet curable resin can rise due to the surface tension at the outer peripheral portion. For example, when a light transmission layer is formed by a spin coating method, such bulging of the resin causes, for example, a variation in the thickness of the light transmission layer, so that the optical path length of the laser light varies, and the reflection film Or, the spot shape on the recording film changes. That is, it becomes difficult to realize stable recording / reproducing characteristics.

  Further, when the intermediate layer is formed by spin coating, when the stamper is placed on the stretched UV curable resin, the stamper and the stretched UV curable resin are caused by the rise of the UV curable resin in the outer peripheral portion. There will be a gap between them. When a gap is formed in this way, air is caught between the ultraviolet curable resin and the stamper, and it becomes difficult to transfer the molding surface of the stamper.

  Therefore, a method has been proposed in which a recess having substantially the same shape as the substrate is provided in the spin tray, the substrate is placed in the recess, and the spin tray is rotated to stretch the ultraviolet curable resin (for example, see Patent Document 1).

JP 2004-288270 A

  However, according to the knowledge of the present inventor, even with the above-described method, it is not possible to sufficiently suppress the swelling of the UV curable resin at the outer peripheral portion and the wraparound of the resin to the side surface of the substrate, and light transmission with excellent uniformity. It is difficult to realize an optical recording medium having a layer, an optical recording medium in which no resin wraps around the side surface of the substrate, or the like. Such non-uniformity of the light transmission layer and the penetration of the ultraviolet curable resin into the side surface of the substrate are particularly problematic in high-density optical recording media such as BD and HD DVD (High Definition Digital Versatile Disc).

  Accordingly, an object of the present invention is to provide an optical recording medium manufacturing method and a manufacturing method thereof capable of suppressing the swelling and wraparound of the photocurable resin in the outer peripheral portion when the photocurable resin is stretched by a spin coating method. It is to provide a manufactured optical recording medium.

In order to solve the above-described problems, the present invention provides an optical recording medium in which a first information signal portion, an intermediate layer, a second information signal portion, and a light transmission layer are sequentially laminated on a substrate.
An optical recording medium is characterized in that a photocurable resin is wrapped around the outer peripheral surface of the substrate with a thickness of 25 μm or less.

The present invention provides a method of manufacturing an optical recording medium in which a first information signal portion, an intermediate layer, a second information signal portion, and a light transmission layer are sequentially laminated on a substrate.
Rotating the substrate and an extension portion having a plane that is almost the same height as the outer periphery of the substrate, extending the photocurable resin onto the first information signal portion, and covering the outer periphery of the substrate with the light shielding portion The stretched photo-curing resin is irradiated with weak light to change it into a gel-like semi-cured state, and the substrate and the extension are rotated again to remove excess photo-curing resin on the outer periphery. By pressing the stamper on the cured photocurable resin and irradiating the photocurable resin with light to cure the photocurable resin,
An intermediate layer is formed.

  In the present invention, the wrapping of the photo-curable resin to the side surface of the substrate does not wrap around a part of the side surface of the substrate but also includes the wrapping of the entire side surface of the substrate.

  In this invention, the substrate and the extension portion having a plane that is almost the same height as the outer periphery of the substrate are rotated to extend the photocurable resin onto the first information signal portion. The photocurable resin can be continuously stretched beyond the plane of the extension.

  In addition, by irradiating the photocurable resin stretched on the substrate with weak light to change it into a gel-like semi-cured state, the substrate is rotated again to remove the excess photocurable resin on the outer peripheral portion. When the stamper is pressed onto the semi-cured photocurable resin, the photocurable resin can be prevented from spreading outward from the side surface on the outer peripheral side of the substrate. Therefore, the wrapping of the photocurable resin and the generation of burrs can be suppressed.

  In addition, the light-curing resin stretched on the substrate is irradiated with weak light to change it into a gel-like semi-cured state, and then the substrate is rotated again, so that excess photo-curing resin on the outer periphery is removed. it can.

  In the present invention, it is preferable that a gap of 5 μm or more and 90 μm or less is provided between the substrate and the extension. By setting the gap in this numerical range, it is possible to prevent the photocurable resin from entering between the substrate and the extension when the photocurable resin is stretched. That is, it can suppress that photocurable resin wraps around the outer periphery of a board | substrate.

  In the present invention, it is preferable to provide a through hole below the plane of the extension. By providing this through hole, when the photocurable resin is stretched, the photocurable resin that has entered between the substrate and the extension portion can be discharged to the outside through the through hole. Therefore, it can suppress that photocurable resin remains between a board | substrate and an extension part.

  As described above, according to the present invention, when the ultraviolet curable resin is applied on the substrate, the swelling and wraparound of the ultraviolet curable resin in the outer peripheral portion can be suppressed. Therefore, it is possible to realize an optical recording medium having a light transmission layer with excellent uniformity and an optical recording medium having an intermediate layer provided with an excellent molding surface.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In all the drawings of the following embodiments, the same or corresponding parts are denoted by the same reference numerals.

(1) First Embodiment (1-1) Configuration of Optical Recording Medium FIG. 1 is a sectional view showing a configuration example of an optical recording medium according to the first embodiment of the present invention. This optical recording medium 10 is a rewritable, write once or read-only optical recording medium having two recording films, and includes a first recording film (L0 film) 2, an intermediate layer 3, and a second recording film. The (L1 film) 4 and the light transmission layer 5 are sequentially laminated on the substrate 1.

  In the optical recording medium 10 according to the first embodiment, the information signal is recorded or reproduced by irradiating the first recording film 2 or the second recording film 4 with the laser light 7 from the light transmission layer 5 side. Done. For example, the laser beam 7 having a wavelength in the range of 400 nm to 410 nm is condensed by the objective lens 6 having a numerical aperture in the range of 0.84 to 0.86, and the first light is transmitted from the light transmission layer 5 side. By irradiating the recording film 2 or the second recording film 4, information signals are recorded or reproduced. An example of such an optical recording medium 10 is BD-RE (Blu-ray Disc-REwritable).

  Hereinafter, the substrate 1, the first recording film 2, the intermediate layer 3, the second recording film 4, and the light transmission layer 5 constituting the optical recording medium 10 will be described in order.

(substrate)
The substrate 1 has an annular shape with an opening (hereinafter referred to as a center hole) formed in the center. One main surface of the substrate 1 is an uneven surface 1a, and a first recording film 2 is formed on the uneven surface 1a. Hereinafter, the concave portion of the uneven surface 1a is referred to as in-groove, and the convex portion of the uneven surface 1a is referred to as on-groove.

  Examples of the shape of the in-groove and the on-groove include various shapes such as a spiral shape and a concentric shape. In-grooves and / or on-grooves are wobbled (meandered) to add address information.

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

  As the material of the substrate 1, for example, a plastic material such as polycarbonate resin, polyolefin resin, or acrylic resin, or glass can be used. In consideration of cost, it is preferable to use a plastic material as the material of the substrate 1. In addition, an ultraviolet curable resin wraps around the outer peripheral surface of the substrate 1. The wraparound amount of the ultraviolet curable resin, that is, the thickness d of the ultraviolet curable resin is preferably 25 μm or less, more preferably 15 μm or less.

(First recording film)
The first recording film 2 is a recording film capable of recording or reproducing information signals by irradiation with laser light. The first recording film is, for example, a laminated film in which a reflective film, a lower dielectric film, a phase change recording film, and an upper dielectric film are sequentially laminated on the substrate 1. As a material for forming the phase change material film, a phase change material that undergoes a reversible state change upon irradiation with laser light can be used. As such a phase change material, for example, a eutectic phase change material or a compound phase change material that causes a reversible phase change between an amorphous state and a crystalline state can be used.

(Middle layer)
The intermediate layer 3 is made of a resin material having transparency, and as such a material, for example, a plastic material such as a polycarbonate resin, a polyolefin resin, or an acrylic resin can be used. The surface on the light transmission layer 5 side of the intermediate layer 3 is an uneven surface 2 a composed of in-grooves and on-grooves, like the substrate 1. A second recording film 4 is formed on the uneven surface 2a. In addition, a minute step is provided on the outer peripheral surface of the intermediate layer 3. This level difference is caused by an optical recording medium manufacturing method described later.

(Second recording film)
The second recording film 4 is a recording film capable of recording or reproducing information signals by irradiation with laser light. The second recording film 4 is a laminated film in which, for example, a reflective film, a lower dielectric film, a phase change recording film, and an upper dielectric film are sequentially laminated on the intermediate layer 3. As a material for forming the phase change material film, a phase change material that undergoes a reversible state change upon irradiation with laser light can be used. As such a phase change material, for example, a eutectic phase change material or a compound phase change material that causes a reversible phase change between an amorphous state and a crystalline state can be used.

(Light transmission layer)
The light transmissive layer 5 includes, for example, a light transmissive sheet (film) having an annular shape and an adhesive layer for bonding the light transmissive sheet to the substrate 1. The adhesive layer is made of, for example, an ultraviolet curable resin or a pressure sensitive adhesive (PSA). The thickness of the light transmission layer 5 is preferably selected from the range of 10 μm or more and 177 μm or less, for example, 75 μm. By combining such a thin light transmission layer 5 with an objective lens having a high NA (numerical aperture) of, for example, about 0.85, high-density recording can be realized.

  The light-transmitting sheet is preferably made of a material having a low absorption ability with respect to laser light used for recording and / or reproduction, specifically, a material having a transmittance of 90% or more. Examples of the material for the light transmissive sheet include polycarbonate resin materials and polyolefin resins (for example, ZEONEX (registered trademark)). The inner diameter (diameter) of the light transmission layer 5 is selected to be 22.7 mm, for example.

(1-2) Configuration of Spin Coating Device Next, the configuration of the spin coating device used for forming the above-described intermediate layer 3 will be described with reference to FIGS. 2 and 3. FIG. 2 is a cross-sectional view showing a configuration example of the spin coater. FIG. 3 is a top view showing a configuration example of the spin coater.

  The spin coater includes a spin tray 21 and an ultraviolet irradiation device (hereinafter referred to as UV irradiation device) 23. A spindle motor (not shown) is provided below the spin tray 21, and the spin tray 21 rotates by driving the spindle motor. The spin tray 21 has a configuration that can move in the vertical direction. The UV irradiation device 23 is for uniformly irradiating ultraviolet light (hereinafter referred to as UV light) from the inner periphery to the outer periphery of the substrate 1 to cure the ultraviolet curable resin stretched on the substrate 1. . Although FIG. 2 shows an example in which the entire surface of the substrate 1 is irradiated by one UV irradiation device 23, the UV irradiation device 23 is not limited to this example. For example, a plurality of UV irradiation devices 23 arranged in series in the radial direction of the substrate 1 may be used.

  The spin tray 21 has a mounting surface 21 a for mounting the optical recording medium 10. A center pin 22 protruding from the placement surface 21a is provided at the center of the placement surface 21a. The substrate 1 is positioned by fitting the center hole 1b of the optical recording medium 10 to the center pin 22.

  The spin tray 21 is provided with an outer ring 24 so as to surround the mounting surface 21 a, and the above-described center pin 22 is located at the center of the outer ring 24. The outer peripheral ring 24 is an example of an extension portion, and in order to continuously extend the extension of the UV curable resin beyond the outer periphery of the substrate 1 when the UV curable resin is extended onto the substrate 1 by spin coating. belongs to. The outer peripheral ring 24 rotates in synchronization with the spin tray 21.

  The outer peripheral ring 24 protrudes from the mounting surface 21a by the thickness of the substrate 1, and the protruding surface has a planar shape parallel to the mounting surface 21a. Therefore, when the substrate 1 is placed on the placement surface 21a, the one main surface of the substrate 1 and the upper surface of the outer peripheral ring 24 are substantially the same height. Thereby, when the ultraviolet curable resin is stretched to one main surface of the substrate 1, the stretch of the ultraviolet curable resin can be continuously extended beyond the outer periphery of the substrate 1 to the projecting surface of the outer peripheral ring 24.

  The inner diameter of the outer peripheral ring 24 is selected to be substantially the same as the diameter of the substrate 1 placed on the placement surface 21a. The clearance (clearance) between the inner peripheral surface of the outer peripheral ring 24 and the outer peripheral surface of the substrate 1 placed on the placement surface 21a is preferably set to 5 μm to 90 μm, and more preferably 22 μm to 60 μm. By setting the clearance within a numerical range of 5 μm to 90 μm, it is possible to prevent the UV curable resin or the like from entering the outer peripheral surface of the substrate 1 when the intermediate layer 3 is formed. By setting the clearance within a numerical range of 22 μm to 60 μm, it is possible to further suppress the UV curable resin or the like from entering the outer peripheral surface of the substrate 1 when the intermediate layer 3 is formed.

  Further, the outer peripheral ring 24 is provided with a plurality of discharge holes 24a penetrating from the inner peripheral surface toward the outer peripheral surface, for example, in the circumferential direction. By providing the discharge holes 24 a, when the ultraviolet ray curable resin is stretched on the substrate 1 by rotating the spin tray 21, the ultraviolet curable resin that has entered between the substrate 1 and the outer ring 24 is removed from the outer ring 24. Can be discharged to the outside. Therefore, it is possible to suppress the ultraviolet curable resin from remaining between the substrate 1 and the outer ring 24. The shape of the discharge hole 24a is not particularly limited, but it is preferable that the discharge hole 24a is elongated in the circumferential direction from the viewpoint of improving the discharge of the ultraviolet curable resin.

  The spin coater is further provided with an outer peripheral mask 25. When the substrate 1 is irradiated with UV light, the spin coater is configured so that the outer peripheral portion of the substrate 1 can be covered with the outer peripheral mask 25. The outer peripheral mask 25 is a light shielding portion that shields the outer peripheral portion of the substrate 1 from the UV light emitted from the UV irradiation device 23. The outer peripheral mask 25 is made of a material such as metal capable of blocking UV light. The outer peripheral mask 25 has a protrusion 25a at the tip on the side facing the mounting surface 21a. By providing the protruding portion 25a, it is possible to reduce leakage of UV light to the outer peripheral portion of the substrate 1.

  If the inner diameter of the outer peripheral mask 25 is too narrow, the number of uncured portions on the outer peripheral portion of the substrate 1 increases, and this uncured portion is shaken off during spin coating. Therefore, the signal area becomes narrow, and for example, the signal area required by the standard cannot be secured. On the other hand, when the inner diameter of the outer peripheral mask 25 is too large, the stretched ultraviolet curable resin is in a semi-cured state up to the outer peripheral portion of the substrate 1 or a portion outside it. Therefore, the outer diameter of the optical recording medium increases, and exceeds the outer diameter of the substrate required by the standard, for example. In consideration of the above points, it is preferable to appropriately select the inner diameter of the outer peripheral mask 25, that is, the protruding width of the outer peripheral mask 25 from the side surface of the substrate, so as to satisfy the desired standard of the optical recording medium.

(1-3) Manufacturing Method of Optical Recording Medium Next, a manufacturing method of the optical recording medium according to the first embodiment of the present invention will be described with reference to FIGS.

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

(First recording film forming step)
Next, a reflective film, a lower dielectric film, a phase change recording film, and an upper dielectric film are sequentially stacked on the substrate 1 by sputtering, for example. Thereby, the first recording film 2 is formed on the substrate 1.

(Intermediate layer formation process)
Next, as shown in FIG. 4A, the substrate 1 is placed on the placement surface 21 a of the spin tray 21 so that the center hole 1 b of the substrate 1 is fitted to the center pin 22. Next, as shown in FIG. 4A, the ultraviolet curable resin 3a is dropped from the nozzle (not shown) around the center hole 1b, for example, over one turn while rotating the substrate 1.

  Next, as shown in FIG. 4B, the spin tray 21 is rotated at a high speed for 1 to 4 seconds, for example, at a rotational speed in the range of 2500 to 3500 rpm. As a result, the substrate 1 and the outer peripheral ring 24 are rotated at a high speed, the ultraviolet curable resin 3a is stretched over the entire surface of the substrate 1, and excess ultraviolet curable resin is shaken off.

  Further, since the ultraviolet curable resin 3 a extends beyond the outer peripheral portion of the substrate 1 to the protruding surface of the outer peripheral ring 24, the ultraviolet curable resin 3 a wraps around the outer peripheral side surface of the substrate 1 and the outer peripheral portion of the substrate 1. Resin swell is reduced.

  Next, as shown in FIG. 4C, the outer peripheral portion of the substrate 1 is covered with the outer peripheral mask 25. As a result, the ultraviolet curable resin raised at the outer peripheral portion of the substrate 1 is covered with the outer peripheral mask 25. Next, the substrate 1 is rotated, and the upper surface of the substrate 1 is uniformly irradiated with weak UV light, for example, by a plurality of UV irradiation devices 23 arranged in series in the radial direction of the substrate 1. Thereby, the ultraviolet curable resin 3b on the upper surface of the substrate 1 is in a gel-like semi-cured state, and the ultraviolet curable resin 3c on the upper surface of the outer peripheral ring 24 is in an uncured state.

  Next, as shown in FIG. 4D, the spin tray 21 is rotated at a high speed for 1 to 4 seconds at a rotation speed in the range of 3000 to 4500 rpm, for example. Thereby, the board | substrate 1 and the outer periphery ring 24 are rotated at high speed, an excess ultraviolet curing resin is shaken off, and the thickness of the ultraviolet curing resin 3c of the upper surface of the outer periphery ring 24 is reduced. Next, for example, the substrate 1 is unloaded in a direction perpendicular to the placement surface 21a. Thereby, a minute step is formed on the outer peripheral surface of the intermediate layer 3. At this time, it is considered that the ultraviolet curable resin goes around the outer peripheral surface of the substrate 1. In addition, the thickness of the ultraviolet curable resin that wraps around the outer peripheral surface of the substrate is extremely thinner than that in the conventional optical recording medium.

  Next, the substrate 1 is transported onto the table 33 shown in FIG. 5A for forming the intermediate layer 3, and the light-transmitting stamper 27 is applied to the ultraviolet curable resin 3 b uniformly stretched on the upper surface of the substrate 1. Push against each other. The stamper 27 is pressed against the ultraviolet curable resin 3b by, for example, a differential pressure laminating method. Here, the differential pressure laminating method refers to a method in which the stamper 27 is pressed against the ultraviolet curable resin 3b by using a pressure difference generated between a vacuum state and a state where an atmospheric pressure is applied.

  As shown in FIG. 5A, in the differential pressure laminating method, the stamper 27 in a state before being pressed against the substrate 1 is fitted to the small diameter portion on the tip side of the centering pin whose center opening constitutes the support mechanism 32 on the inner peripheral side. The outer peripheral side of the stamper 27 is supported by the outer peripheral side support mechanism 28, and has an appropriate distance from the substrate 1 by the inner peripheral side support mechanism 32 and the outer peripheral side support mechanism 28, and It arrange | positions in the vacuum chamber T of a vacuum state so that one main surface of the stamper 27 and one main surface of the board | substrate 1 may face substantially parallel.

  Next, the vacuum in the vacuum chamber T is broken to release the atmospheric pressure, and a differential pressure between the vacuum and the atmospheric pressure is applied to the stamper 27. At this time, in synchronization with the release of the atmospheric pressure, the holding state of the inner peripheral support mechanism 32 and the outer peripheral support mechanism 28 for maintaining the distance between the stamper 27 and the substrate 1 is released. Release of the atmospheric pressure and the release of the support mechanism 32 on the inner peripheral side and the support mechanism 28 on the outer peripheral side in synchronism with the release of the atmospheric pressure cause the inner peripheral portion of the stamper 27 to be pressed against the substrate 1 while being bent downward, thereby causing bubbles. Can be reduced.

  Next, as shown in FIG. 5B, the substrate 1 is irradiated with UV light from the vicinity of the central portion of the stamper 27 to the vicinity of the outer peripheral portion by, for example, a UV irradiation device 29 arranged so as to be orthogonal to the radial direction of the substrate 1. As a result, the UV curable resin 3b in a semi-cured state is made into a UV curable resin that is completely cured by the UV light transmitted through the stamper 27.

  Next, the substrate 1 is transferred to another table (not shown) for peeling the stamper 27 from the substrate 1, and the stamper 27 is removed as shown in FIG. 5C. Thereby, the intermediate layer 3 provided with the in-groove and the on-groove is obtained.

(Second Recording Film Formation Process)
Next, a reflective film, a lower dielectric film, a phase change recording film, and an upper dielectric film are sequentially stacked on the intermediate layer 3 by sputtering, for example. Thereby, the second recording film 4 is formed on the intermediate layer 3.

(Light transmission layer forming process)
Next, an annular light-transmitting sheet is bonded to the uneven surface 2a side on the substrate 1 using, for example, a pressure-sensitive adhesive (PSA) uniformly applied in advance to one main surface of the sheet. Thereby, the light transmission layer 5 is formed so as to cover the laminated film laminated on the substrate 1.
Through the above steps, the optical recording medium 10 shown in FIG. 1 is obtained.

(2) Second Embodiment (2-1) Configuration of Optical Recording Medium FIG. 6 is a cross-sectional view showing a configuration example of an optical recording medium according to the second embodiment of the present invention. This optical recording medium 10 is a rewritable optical recording medium having a single-layer recording film, and is configured by sequentially laminating a recording film 41 and a light transmission layer 5 on a substrate 1. The substrate 1 is the same as in the first embodiment described above, and the recording film 41 is the same as the second recording film 4 in the first embodiment described above. The light transmission layer 5 is formed by curing an ultraviolet curable resin. The thickness of the light transmission layer 5 is preferably selected from the range of 10 μm or more and 177 μm or less, for example, 100 μm.

(2-2) Manufacturing Method of Optical Recording Medium Next, a manufacturing method of the optical recording medium 10 according to the second embodiment of the present invention will be described with reference to FIG. The configuration of the spin coater used for forming the light transmission layer 5 is the same as that in the first embodiment described above, and a description thereof will be omitted.

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

(Recording film formation process)
Next, a reflective film, a lower dielectric film, a phase change recording film, and an upper dielectric film are sequentially stacked on the substrate 1 by sputtering, for example. Thereby, the recording film 41 is formed on the substrate 1.

(Light transmission layer forming process)
Next, as shown in FIG. 7A, the substrate 1 is placed on the placement surface 21 a of the spin tray 21 so that the center hole 1 b of the substrate 1 is fitted to the center pin 22. Next, as shown in FIG. 4A, the ultraviolet curable resin 5a is dropped from the nozzle (not shown) around the center hole 1b, for example, over one turn while rotating the substrate 1.

  Next, as shown in FIG. 7B, the spin tray 21 is rotated at a high speed for 1 to 4 seconds, for example, at a rotational speed in the range of 2500 to 3500 rpm. As a result, the substrate 1 and the outer ring 24 are rotated at high speed, the ultraviolet curable resin 5a is stretched over the entire surface of the substrate 1, and the excess ultraviolet curable resin 5a is shaken off. In addition, since the ultraviolet curable resin 5 a extends beyond the outer peripheral portion of the substrate 1 to the protruding surface of the outer peripheral ring 24, the ultraviolet curable resin 5 a wraps around the outer peripheral side surface of the substrate 1 and the outer peripheral portion of the substrate 1. Resin swell is reduced.

  Next, as shown in FIG. 7C, the outer peripheral portion of the substrate 1 is covered with the outer peripheral mask 25. As a result, the ultraviolet curable resin 5 a raised at the outer peripheral portion of the substrate 1 is covered with the outer peripheral mask 25. Next, UV light is uniformly irradiated on the upper surface of the substrate 1 by a plurality of UV irradiation devices 23 arranged in series in the radial direction of the substrate. Thereby, the ultraviolet curable resin 5b on the upper surface of the substrate 1 is in a semi-cured state, and the ultraviolet curable resin 3c on the upper surface of the outer peripheral ring 24 is in an uncured state.

Next, as shown in FIG. 7D, the spin tray 21 is rotated at a high speed for 1 to 4 seconds at a rotational speed in the range of 3000 to 4500 rpm, for example. Thereby, the board | substrate 1 and the outer periphery ring 24 are rotated at high speed, an excess ultraviolet curing resin is shaken off, and the thickness of the ultraviolet curing resin 5c of the upper surface of the outer periphery ring 24 is reduced. Next, the UV irradiation device 23 irradiates the upper surface of the substrate 1 with UV light. Thereby, the semi-cured ultraviolet curable resin 5b stretched on the upper surface of the substrate 1 is completely cured, and the light transmission layer 5 is formed.
Through the above steps, the optical recording medium 10 shown in FIG. 6 is obtained.

  EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited only to these Examples.

  First, the ultraviolet curable resin was stretched and cured by the above spin coater and a conventional spin coater, and the thickness uniformity of the resin layer was evaluated.

Example 1
First, the substrate 1 having an in-groove and an on-groove provided on one main surface was formed by an injection molding method. As the resin material, polycarbonate resin was used. Next, the first recording film 2 was formed on the substrate 1 by sputtering.

  Next, the substrate 1 is transported to the spin coater shown in FIG. 2, and the substrate 1 is placed on the placement surface 21 a of the spin tray 21 so that the center hole 1 b of the substrate 1 is fitted to the center pin 22. did. Next, the ultraviolet curable resin 3a was dropped from the nozzle over the circumference of the center hole 1b while rotating the substrate 1.

  Next, the spin tray 21 was rotated at a high speed for 1 to 4 seconds at a rotation speed in the range of 2500 to 3500 rpm, and the ultraviolet curable resin 3a was stretched on the substrate 1. The clearance between the substrate 1 and the outer ring 24 was 5 μm.

  Next, after the outer peripheral portion of the substrate 1 is covered with the outer peripheral mask 25, the UV irradiation device 23 uniformly irradiates the upper surface of the substrate 1 with UV light, and the ultraviolet curable resin 3b stretched on the upper surface of the substrate 1 is applied. Semi-cured. The diameter of the outer peripheral mask 25 having an annular shape was 118 mm. Next, the spin tray 21 is rotated at a high speed for 1 to 4 seconds at a rotation speed in the range of 3000 to 4500 rpm, and the excess UV curable resin on the outer peripheral portion of the substrate 1 is shaken off to obtain the thickness of the UV curable resin 3c. Reduced.

  Next, the substrate 1 is moved to a table for forming an intermediate layer, and the outer peripheral portion of the substrate 1 is covered with the outer peripheral mask 31, and then, the upper surface of the substrate 1 is irradiated with UV light. The stretched semi-cured UV curable resin 3b was used as a fully cured UV curable resin.

Comparative Example 1
FIG. 8 shows a configuration of a spin coater used for manufacturing the optical recording medium 10 of the comparative example. As shown in FIG. 8, this spin coater is the same as the spin coater used in Example 1 described above except that the outer ring 24 and the outer mask 25 are omitted. Using this spin coater, a sample was produced as follows.

  First, in the same manner as in Example 1, the substrate 1 was molded, and the first recording film 2 was formed on the substrate 1. Next, the substrate 1 is transported to the spin coater shown in FIG. 8, and the substrate 1 is placed on the placement surface 21 a of the spin tray 21 so that the center hole 1 b of the substrate 1 is fitted to the center pin 22. did. Next, the ultraviolet curable resin 3a was dropped from the nozzle over the circumference of the center hole 2b while rotating the substrate 1.

  Next, for example, the spin tray 21 was rotated at a high speed for 1 to 4 seconds at a rotational speed in the range of 2500 to 3500 rpm, and the ultraviolet curable resin 3 a was stretched on the upper surface of the substrate 1. Next, UV light was uniformly irradiated on the upper surface of the substrate 1 by the UV irradiation device 23 to completely cure the stretched ultraviolet curable resin 3a.

  Next, the shape of the outer peripheral part of Example 1 and Comparative Example 1 obtained as described above was evaluated. For this evaluation, P-15 manufactured by KLA TENCOR was used. FIG. 9 shows the shape of the outer periphery of the first embodiment. FIG. 10 shows the shape of the outer peripheral portion of Comparative Example 1.

  From FIG. 9 to FIG. 10, in Comparative Example 1, the rise of the ultraviolet curable resin 3 a in the outer peripheral portion of the substrate 1 has reached about 17 μm, whereas in Example 1, the ultraviolet light in the outer peripheral portion of the substrate 1 is reached. It can be seen that the rise of the cured resin 3a is reduced to about 2 μm.

  Next, samples of Examples 2 to 7 were prepared, and the clearance between the substrate 1 and the outer ring 24 was examined.

Example 2
First, in the same manner as in Example 1, the substrate 1 was molded, and the first recording film 2 was formed on the substrate 1. Next, the substrate 1 is transported to the spin coater shown in FIG. 2, and the substrate 1 is placed on the placement surface 21 a of the spin tray 21 so that the center hole 1 b of the substrate 1 is fitted to the center pin 22. did. Next, the ultraviolet curable resin 3a was dropped from the nozzle over the circumference of the center hole while rotating the substrate 1.

  Next, for example, the spin tray 21 was rotated at a high speed for 2 seconds at a rotational speed in the range of 2500 to 3500 rpm, and the ultraviolet curable resin 3 a was stretched on the substrate 1. The clearance between the substrate 1 and the outer ring 24 was 4 μm.

  Next, after the outer peripheral portion of the substrate 1 is covered with the outer peripheral mask 25, the UV irradiation device 23 uniformly irradiates the upper surface of the substrate 1 with UV light, and the ultraviolet curable resin 3b stretched on the upper surface of the substrate 1 is applied. Semi-cured. The diameter of the outer peripheral mask 25 having an annular shape was 118 mm. Next, the spin tray 21 was rotated at a high speed for 4 seconds at a rotational speed in the range of 3000 to 4500 rpm, and the excess UV curable resin on the outer periphery of the substrate 1 was shaken off to reduce the thickness of the UV curable resin c. .

  Next, the substrate 1 is transported onto a table 33 for forming the intermediate layer 3, and a light-transmitting stamper 27 is pushed against the ultraviolet curable resin 3 b uniformly stretched on the upper surface of the substrate 1. Combined. The stamper 27 was pressed by a differential pressure laminating method. Next, the UV irradiation device 29 irradiates the upper surface of the substrate 1 with UV light, and the semi-cured ultraviolet curable resin 3b stretched on the upper surface of the substrate 1 is used as a fully cured ultraviolet curable resin. . Next, the substrate 1 was transported to another table for peeling the stamper 27 from the substrate 1, and the stamper 27 was removed. Thereby, the intermediate layer 3 provided with the in-groove and the on-groove was obtained.

  Next, the second recording film 4 was formed on the uneven surface 2a of the intermediate layer 3 by sputtering. Next, the annular light-transmitting sheet was bonded to the concave-convex surface 2a side of the intermediate layer 3 using, for example, a pressure-sensitive adhesive (PSA) previously uniformly applied to one main surface of the sheet. . Thereby, the light transmission layer 5 was formed so as to cover the laminated film laminated on the substrate 1. The target sample was obtained through the above steps.

Example 3
A sample was obtained in the same manner as in Example 2 except that the clearance between the substrate 1 and the outer ring 24 was set to 5 μm.

Example 4
A sample was obtained in the same manner as in Example 2 except that the clearance between the substrate 1 and the outer ring 24 was 22 μm.

Example 5
A sample was obtained in the same manner as in Example 2 except that the clearance between the substrate 1 and the outer peripheral ring 24 was set to 60 μm.

Example 6
A sample was obtained in the same manner as in Example 2 except that the clearance between the substrate 1 and the outer ring 24 was 90 μm.

Example 7
A sample was obtained in the same manner as in Example 2 except that the clearance between the substrate 1 and the outer ring 24 was 100 μm.

  Next, the amount of UV curable resin wraparound at the outer peripheral portion of the substrate 1 of Examples 2 to 7 obtained as described above was measured. FIG. 11 is a schematic diagram illustrating the amount of UV curable resin wraparound in the outer peripheral portion of the substrate 1 of Examples 2 to 7. In FIG. 11, the case where the ultraviolet curable resin wraps around a part of the outer peripheral surface of the substrate 1 is illustrated for convenience, but actually, the ultraviolet curable resin wraps around the entire outer peripheral surface of the substrate 1. . In addition, the amount of wraparound was measured at eight positions for each of the substrates of Examples 2 to 7. In addition, a CNC image measuring device (trade name: Quick Vision PRO) is used for clearance measurement, and a CNC image measuring device (trade name: Quick Vision PRO) is used for measuring the amount of wraparound. Was used.

In Table 1, the measurement result of the amount of wraparound of Examples 2-7 is shown. In Table 1, the determination results “◯”, “Δ”, and “×” indicate that the amount of wraparound d is in the following range.
“◯”: 0 ≦ d ≦ 15 μm, “Δ”: 15 μm <d ≦ 25 μm, “×”: 25 μm <d

  In Example 2 (clearance 4 μm) and Example 7 (clearance 100 μm), the determination results are “Δ” and “×” depending on the measurement position, whereas in Examples 3 to 7 (clearance 5 μm to 90 μm). It can be seen that the determination results are “◯” at all measurement positions. That is, it can be seen that the amount of wraparound to the outer shape of the substrate 1 can be reduced to 15 μm or less by setting the clearance in the range of 5 μm to 90 μm.

  Focusing on Examples 3 to 6 (clearance 5 μm to 90 μm), Examples 4 to 5 (clearance 22 μm to 60 μm) are compared to Example 3 (clearance 5 μm) and Example 6 (clearance 90 μm). It can be seen that the amount of wraparound to the outer shape of the substrate 1 can be further reduced. That is, it can be seen that the amount of wraparound to the outer shape of the substrate 1 can be further reduced by setting the clearance in the range of 22 μm to 60 μm.

  The first and second embodiments of the present invention have been specifically described above. However, the present invention is not limited to the first and second embodiments described above, and is based on the technical idea of the present invention. Various variations based on this are possible.

  For example, the numerical values given in the first to second embodiments are merely examples, and different numerical values may be used as necessary.

  In the first to second embodiments described above, the present invention is applied to an optical recording medium having a two-layer recording film. However, the present invention applies to an optical recording medium having a recording film having three or more layers. It is also possible to apply.

  In the first and second embodiments described above, the example in which the present invention is applied to the method of manufacturing the optical recording medium having the intermediate layer or the light transmission layer has been described. However, the optical recording medium having the hard code layer is described. The present invention may be applied to the manufacturing method.

  In the first embodiment, the light transmissive sheet 5 is bonded to the substrate 1 with a pressure-sensitive adhesive to produce the light transmissive layer 5. However, as in the second embodiment, ultraviolet light is used. The light transmission layer 5 may be formed by stretching and curing the cured resin 3a.

  In the first embodiment described above, the light transmissive sheet 5 is bonded to the substrate 1 with the pressure-sensitive adhesive to produce the light transmissive layer 5. However, the light transmissive sheet is made of the ultraviolet curable resin. 1 may be laminated to form the light transmission layer 5. The light transmission layer 5 is formed as follows, for example.

  First, for example, an ultraviolet curable resin is stretched on the second recording film 2 to a thickness of about 10 μm to 20 μm. At this time, the ultraviolet curable resin is stretched using the spin coater shown in FIG. 2 in the same manner as in the second embodiment. Next, after placing the light transmissive sheet on the ultraviolet curable resin stretched on the substrate 1, for example, the ultraviolet curable resin is irradiated with UV light from the light transmissive sheet side to cure the ultraviolet curable resin. Thus, the light transmission layer 5 is formed.

  In the first to second embodiments described above, the case where the present invention is applied to the single-plate type optical recording medium 10 having a configuration in which the light transmission layer 5 is formed on the substrate 1 has been described. The present invention may be applied to a bonded optical recording medium having a configuration in which the first and second substrates are bonded together. Examples of the bonded optical recording medium to which the present invention can be applied include DVD and HD DVD.

  In the first and second embodiments described above, the case of irradiating UV light from the side opposite to the substrate 1 has been described. However, when the transmittance of the first recording film 2 and the recording film 41 is high. It is also possible to irradiate UV light from the substrate 1 side. For example, in the case of a write-once type optical recording medium, the recording film has a high transmittance, so that it is possible to irradiate UV light from the substrate 1 side. Thus, a stamper can be used from a metal etc. by irradiating UV light from the substrate 1 side. Therefore, since the durability of the stamper is improved, a plurality of intermediate layers 3 can be formed using one stamper. That is, the cost of the optical recording medium can be reduced.

  In the first to second embodiments described above, the case where the present invention is applied to a rewritable optical recording medium has been described as an example. However, the present invention is not limited to this example. The present invention can also be applied to write-once and read-only optical recording media.

It is sectional drawing which shows one structural example of the optical recording medium by 1st Embodiment of this invention. It is sectional drawing which shows one structural example of a spin coater. It is a top view which shows one structural example of a spin coater. It is a schematic diagram for demonstrating the manufacturing method of the optical recording medium by 1st Embodiment of this invention. It is a schematic diagram for demonstrating the manufacturing method of the optical recording medium by 1st Embodiment of this invention. It is sectional drawing which shows the example of 1 structure of the optical recording medium by the 2nd Embodiment of this invention. It is a schematic diagram for demonstrating the manufacturing method of the optical recording medium by 2nd Embodiment of this invention. 6 is a cross-sectional view showing a configuration of a spin coater used for manufacturing the optical recording medium 10 of Comparative Example 1. FIG. 3 is a schematic diagram illustrating a shape of an outer peripheral portion of Example 1. FIG. 6 is a schematic diagram illustrating a shape of an outer peripheral portion of Comparative Example 1. FIG. It is a schematic diagram which shows the wraparound amount of the ultraviolet curable resin in the outer peripheral part of the board | substrate 1 of Examples 2-7.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Substrate 1a, 2a ... Uneven surface 1b ... Center hole 2 ... Recording film 2b ... Center hole 3 ... Intermediate layer 3a, 3b, 3c, 3d ... UV curable resin DESCRIPTION OF SYMBOLS 4 ... Recording film 5 ... Light transmission layer 5a, 5b, 5c, 5b ... UV curable resin 6 ... Objective lens 7 ... Laser beam 10 ... Optical recording medium 21 ... Spin Tray 21a ... Placement surface 22 ... Center pin 23 ... Irradiation device 24 ... Outer ring 24a ... Discharge hole 25, 31 ... Outer mask 25a ... Projection 26 ... Infrared irradiation device 27 ... Stamper 28, 32 ... Support mechanism 29, 30 ... UV irradiation device 33 ... Table 41 ... Recording film

Claims (5)

In an optical recording medium in which a first information signal portion, an intermediate layer, a second information signal portion, and a light transmission layer are sequentially laminated on a substrate,
An optical recording medium, wherein a photocurable resin is wrapped around the outer peripheral surface of the substrate with a thickness of 25 μm or less.   The optical recording medium according to claim 1, wherein a step is provided on the outer peripheral surface of the intermediate layer. Rotating the substrate and an extension portion having a plane substantially the same height as the outer periphery of the substrate, the photocurable resin is stretched on the first information signal portion, and the outer periphery portion of the substrate is shielded from the light shielding portion. The stretched photo-curing resin is irradiated with light and semi-cured, and the substrate and the extension are rotated again to remove excess photo-curing resin on the outer peripheral portion and semi-cured. By pressing a stamper on the photocurable resin and irradiating the photocurable resin with light to cure the photocurable resin,
The optical recording medium according to claim 1, wherein the intermediate layer is formed. In the method of manufacturing an optical recording medium in which a first information signal portion, an intermediate layer, a second information signal portion, and a light transmission layer are sequentially laminated on a substrate,
Rotating the substrate and an extension portion having a plane substantially the same height as the outer periphery of the substrate, the photocurable resin is stretched on the first information signal portion, and the outer periphery portion of the substrate is shielded from the light shielding portion. The stretched photo-curing resin is irradiated with light and semi-cured, and the substrate and the extension are rotated again to remove excess photo-curing resin on the outer peripheral portion and semi-cured. By pressing a stamper on the photocurable resin and irradiating the photocurable resin with light to cure the photocurable resin,
A method for producing an optical recording medium, wherein the intermediate layer is formed.   5. The method of manufacturing an optical recording medium according to claim 4, wherein a gap of 5 μm or more and 90 μm or less is provided between the substrate and the extension portion.

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