JP2004030748A - Optical recording medium and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the occurrence of a corrosion in an information signal part through a part at which an adhesive layer comes into contact with the atmosphere. <P>SOLUTION: In an optical recording medium characterized by being provided with an information signal part 1c and a light transmitting layer 2 provided with a light transmitting sheet 2a having an opening at a center part and an adhesive layer 2b for sticking this light transmitting sheet 2b to one main plane of a replica substrate 1a; the medium is provided with an inner periphery enclosure part 3a covering at least a part at which the adhesive layer 2b comes into contact with the atmosphere in the inner periphery part of the light transmitting layer 2 and/or an outer periphery enclosure part 3b covering at least a part at which the adhesive layer 2b comes into contact with the atmosphere in the outer periphery part of the light transmitting layer 2. <P>COPYRIGHT: (C)2004,JPO

Description

【００６９】
表１から、透湿度が７５ｇ／ｃｍ^２・２４ｈを越えた封入部を備えたサンプルでは、外周領域に腐食が観測されたのに対し、透湿度が７５ｇ／ｃｍ^２・２４ｈ以下である封入部を備えたサンプルでは、外周領域に腐食が観測されなかった。すなわち、封入部の透湿度を７５ｇ／ｃｍ^２・２４ｈ以下にすることにより、封入部の腐食防止の効果をさらに向上させることができる。
【００７０】
さらに、本発明者は、封入部による腐食防止効果をさらに向上させるべく、封入部の残留塩素イオン濃度範囲を検討した。残留塩素イオン濃度範囲の検討は、以下のようにして行った。
【００７１】
まず、第１の実施形態による光ディスクと同一の構成を有し、外周封入部を構成する紫外線構成樹脂の塩素イオン濃度が互いに異なるサンプルＦ、サンプルＧ、サンプルＨおよびサンプルＩを製造した。なお、これらのサンプルの外周封入部の厚さｄ_２は、０．１ｍｍである。また、紫外線硬化樹脂の透湿度は、７５ｇ／ｃｍ^２・２４ｈである。この透湿度は、温度４０℃、湿度９０％の環境下において、紫外線硬化樹脂からなる、１００μｍ厚のシート状サンプルを、２４時間維持することにより測定したものである。ここで、塩素イオン濃度の検討範囲は０．１〜１．５ｐｐｍの範囲であり、塩素イオン濃度の値はイオンクロマトグラフにより測定したものである。
【００７２】
そして、各サンプルに対して、温度８０℃、湿度８５％の環境下に２００時間維持する加速度試験を行った後、情報信号部の外周領域を目視により観測し、光ディスクの外周部に腐食が生じているか否かを判定した。
【００７３】
表２に、各サンプルの塩素イオン濃度と判定結果を示す。なお、表２において、サンプルの外周領域に腐食が観測されなかった場合には判定結果を○により表し、サンプルの外周領域に腐食が観測された場合には判定結果を×により表すものとする。
【００７４】
【表２】

【００７５】
表２から、透湿度が１．０ｐｐｍを越えた封入部を備えたサンプルでは、外周領域に腐食が観測されたのに対し、塩素イオン濃度が１．０ｐｐｍ以下である封入部を備えたサンプルでは、外周領域に腐食が観測されなかった。すなわち、封入部の塩素イオン濃度を１．０ｐｐｍ以下にすることにより、腐食防止の効果をさらに向上させることができる。
【００７６】
この発明の第１の実施形態によれば、以下のような効果を得ることができる。
光ディスクの光透過層２の内周側の側面および外周側の側面に、接着層２ｂが大気と接触する部分を少なくとも覆う内周封入部３ａおよび外周封入部３ｂが形成されているため、接着層２ｂが大気に接触することを防ぐことができる。したがって、接着層２ｂの大気中に露出した部分が突起部などに接触することがなくなり、光透過層２がディスク基板１から剥がれることを防止することができる。また、接着層２ｂの大気中に露出した部分に埃などの異物が吸着することを防止することができる。さらに、長期使用において、接着層２ｂの大気中に露出した部分を介して情報信号部に腐食が発生することを防止することができる。
【００７７】
また、紫外線硬化樹脂の液状態における表面張力が２０ｍＮ／ｍ〜４０ｍＮ／ｍの範囲内にある紫外線硬化樹脂を用いて内周封入部３ａおよび外周封入部３ｂを形成することにより、光ディスクの所望位置に、所望量の紫外線硬化樹脂を塗布することができる。よって、封入部形成工程における作業性をより向上させることができる。
【００７８】
また、内周封入部３ａおよび外周封入部３ｂの透湿度を、０．１ｇ／ｃｍ^２・２４ｈ〜７５ｇ／ｃｍ^２・２４ｈにすることにより、内周封入部３ａおよび外周封入部３ｂによる腐食防止の効果をさらに向上させることができる。
【００７９】
また、内周封入部３ａおよび外周封入部３ｂの残留塩素イオン濃度を０．０１ｐｐｍ〜１．０ｐｐｍにすることにより、内周封入部３ａおよび外周封入部３ｂによる腐食防止の効果をさらに向上させることができる。
【００８０】
次に、この発明の第２の実施形態について説明する。この発明の第２の実施形態による光ディスクの構成は、第１の実施形態における光ディスクと同様であるので説明を省略する。
【００８１】
以下、この発明の第２の実施形態による光ディスクの製造方法について説明する。第２の実施形態による光ディスクの製造方法において、レプリカ基板成形工程（ステップＳＴ１）から貼り合わせ工程（ステップＳＴ３）までは、第１の実施形態と略同様であるので説明を省略する。
【００８２】
図１０は、この発明の第２の実施形態による封入部形成工程を説明するための図である。まず、光透過層２が形成されたディスク基板１の一主面が、供給部１３に貯められた紫外線硬化樹脂６の液面に対して垂直になるように、光透過層２が形成されたディスク基板１を供給部１３の上方に保持する。
【００８３】
次に、光透過層２が形成されたディスク基板１を回転させるとともに、光透過層２が形成されたディスク基板１を、ディスク基板１および光透過層２の外周部の側壁が、供給部１３に貯められた紫外線硬化樹脂６の液面に接触する位置まで移動させ保持する。この際、ディスク基板１の一主面を、供給部１３に貯められた紫外線硬化樹脂６の液面に対して垂直に保持するようにする。これにより、ディスク基板１および光透過層２の外周部の側壁に紫外線硬化樹脂６が均一に塗布される。
【００８４】
その後、供給部１３に貯められた紫外線硬化樹脂６の液面からディスク基板１を引き離し、ディスク基板１および光透過層２の外周部の側壁に塗布された紫外線硬化樹脂６に紫外線を照射する。これにより、ディスク基板１および光透過層２の外周部の側壁に塗布された紫外線硬化樹脂６が硬化し、外周封入部３ｂが形成される。
【００８５】
これ以後のことは、上述した第１の実施形態と同様であるので説明を省略する。
【００８６】
この発明の第２の実施形態によれば、第１の実施形態と同様の効果を得ることができる。
【００８７】
次に、この発明の第３の実施形態について説明する。図１１は、この発明の第３の実施形態による光ディスクの構成の一例を示す断面図である。
【００８８】
図１１に示すように、光透過層２は、ディスク基板１より小さい外径を有する。光透過層２は、例えば、ディスク基板１より０．２ｍｍ〜１．０ｍｍ小さい外径を有する。ここで、ディスク基板１の直径（外径）は、例えば１２０ｍｍである。外周封入部３ｂは、少なくとも接着層２ａの内周側の側壁を覆うように、好適には、光透過層２の内周側の側壁を覆うように、ディスク基板１の一主面に形成される。
【００８９】
これ以外のことは、第１の実施形態による光ディスクと同様であるので説明を省略する。
【００９０】
次に、この発明の第３の実施形態による光ディスクの製造方法について説明する。第３の実施形態による光ディスクの製造方法において、レプリカ基板成形工程（ステップＳＴ１）から貼り合わせ工程（ステップＳＴ３）までは、第１の実施形態と略同様であるので説明を省略する。
【００９１】
図１２に、ステップＳＴ１からＳＴ３までの工程により形成された、光透過層２が一主面に形成されたディスク基板１の一例を示す。
【００９２】
以下、図１３および図１４を参照しながら封入部形成工程を説明する。まず、光透過層２が一主面に形成されたディスク基板１を回転させるとともに、内周用ディスペンサ１４の先端が光透過層２の内周部の上方に位置するように、内周用ディスペンサ１４を移動させ、外周用ディスペンサ１５の先端が光透過層２の外周部の上方に位置するように、内周用ディスペンサ１５を移動させる。
【００９３】
そして、内周用ディスペンサ１４および外周ディスペンサ１５から紫外線硬化樹脂を滴下する。これにより、光透過層２の内周側の側壁に、均一厚さの紫外線硬化樹脂が塗布されるとともに、光透過層２の外周側の側壁に、均一厚さの紫外線硬化樹脂が塗布される。
【００９４】
最後に、光ディスクの内周部および外周部に塗布された紫外線硬化樹脂に、紫外線を照射する。これにより、光ディスクの内周部および外周部に塗布した紫外線硬化樹脂が硬化し、内周封入部３ａおよび外周封入部３ｂが形成される。具体的には、光透過層２の内周側の側壁に、均一厚さｄ_１を有する外周封入部３ｂが形成され、光透過層２の外周側の側壁に、均一厚さｄ_２を有する外周封入部３ｂが形成される。以上により、目的とする光ディスクが製造される。
【００９５】
これ以後のことは、上述した第１の実施形態により製造方法と同様であるので説明を省略する。
【００９６】
この発明の第３の実施形態によれば、第１の実施形態と同様の効果を得ることができる。
【００９７】
以上、この発明の実施形態について具体的に説明したが、この発明は、上述の実施形態に限定されるものではなく、この発明の技術的思想に基づく各種の変形が可能である。
【００９８】
例えば、上述の実施形態において挙げた数値はあくまでも例に過ぎず、必要に応じてこれと異なる数値を用いてもよい。
【００９９】
また、上述した第１、第２および第３の実施形態において、内周封入部３ａが、光透過層２が設けられている側の面から盛り上がるようにしてもかまわない。
【０１００】
図１５は、光透過層２が設けられている側の面から盛り上がった形状を有する内周封入部３ａを備えた光ディスクの内周部を示す。この内周封入部３ａの盛り上がり幅Ｈは、光ディスクの光透過層２が設けられた側の面を基準にして、０．１ｍｍ以上２．０ｍｍ以下、例えば１．２ｍｍである。これにより、光ディスクを複数枚積み重ねた際に、積み重ねたディスクが互いに接触することを防止するためのスタックリブを形成することができる。
【０１０１】
また、上述した第１、第２および第３の実施形態において、ディスク基板１とシート５との貼り合わせを、真空中にて行うようにしてもかまわない。これにより、気泡の混入をより低減することができ、気泡混入の防止効果をより向上させることができる。したがって、接着むらや気泡混入が少なく、薄型化され、小複屈折で、透明性良好で厚さも均一な光透過層を有し、対物レンズの高ＮＡ化に対応可能な、高信頼性を有する光ディスクを製造することができる。
【０１０２】
また、上述した第１および第２の実施形態においては、外周部に紫外線硬化樹脂を塗布した後、内周部に紫外線硬化樹脂を塗布する例について示したが、紫外線硬化樹脂の塗布の順序は、この実施形態に限られるものではない。例えば、内周部と外周部とに同時に、紫外線硬化樹脂を塗布してもかまわない。また、内周部に紫外線硬化樹脂を塗布した後、外周部に紫外線硬化樹脂を塗布してもかまわない。
【０１０３】
また、この発明の第３の実施形態においては、外周部と外周部とに同時に、紫外線硬化樹脂を塗布する例について示したが、紫外線硬化樹脂塗布の方法は、この実施形態に限定されるものではない。例えば、内周部に紫外線硬化樹脂を塗布した後、外周部に紫外線硬化樹脂を塗布してもかまわない。あるいは、外周部に紫外線硬化樹脂を塗布した後、内周部に紫外線硬化樹脂を塗布してもかまわない。
【０１０４】
【発明の効果】
以上説明したように、この発明によれば、接着層の大気中に露出した部分が突起部などに接触した場合に、保護層が基板から剥がれることを防止することができる。すなわち、光学記録媒体の耐久性を向上することを防止させることができる。
【０１０５】
また、この発明によれば、長期使用において、接着層の大気中に露出した部分を介して情報信号部に腐食が発生することを防止することができる。すなわち、光学記録媒体の耐久性を向上させることができる。
【図面の簡単な説明】
【図１】この発明の第１の実施形態による光ディスクの構成の一例を示す断面図である。
【図２】この発明の第１の実施形態によるディスク基板の構成の一例を示す断面図である。
【図３】この発明の第１の実施形態によるシートの構成の一例を示す断面図である。
【図４】この発明の第１の実施形態による光ディスクの内周部および外周部における拡大断面図である。
【図５】この発明の第１の実施形態による光ディスクの製造方法を説明するためのフローチャートである。
【図６】この発明の第１の実施形態による貼り合わせ工程を説明するためのディスク基板とシートとの斜視図である。
【図７】この発明の第１の実施形態による貼り合わせ工程により光透過層が一主面に形成されたディスク基板の断面図である。
【図８】この発明の第１の実施形態による封入部形成工程を説明するための略線図である。
【図９】この発明の第１の実施形態による封入部形成工程を説明するための略線図である。
【図１０】この発明の第２の実施形態による封入部形成工程を説明するための略線図である。
【図１１】この発明の第３の実施形態による光ディスクの構成の一例を示す断面図である。
【図１２】この発明の第３の実施形態による貼り合わせ工程により光透過層が一主面に形成されたディスク基板の断面図である。
【図１３】この発明の第３の実施形態による封入部形成工程を説明するための略線図である。
【図１４】この発明の第３の実施形態による封入部形成工程を説明するための光ディスクの外周部の断面図である。
【図１５】この発明の第１、第２あるいは第３の実施形態の変形例による光ディスク構成の一例を示す断面図である。
【符号の説明】
１・・・ディスク基板、１ａ・・・レプリカ基板、１ｂ・・・センターホール、１ｃ・・・情報信号部、２・・・光透過層、２ａ・・・光透過性シート、２ｂ・・・接着層、２ｃ・・・貫通孔、３ａ・・・外周封入部、３ｂ・・・外周封入部、４・・・クランプ領域、５・・・シート、１０・・・ロール、１１・・・紫外線硬化樹脂供給部、１２・・・ディスペンサ、１３・・・供給部、１４・・・内周用ディスペンサ、１５・・・外周用ディスペンサ[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an optical recording medium and a method for manufacturing the same, and more particularly, to an optical recording medium for recording and / or reproducing an information signal by irradiating a laser beam from a side provided with a protective layer for protecting an information signal portion. It is suitable for application to a medium.
[0002]
[Prior art]
2. Description of the Related Art In recent years, in the field of information recording, various researches and developments on an optical information recording method have been advanced in various places. This optical information recording method has an advantage that recording and / or reproduction can be performed in a non-contact manner, and that a recording density higher by one digit or more than that of a magnetic recording method can be achieved. Further, this optical information recording method has an additional advantage that it can correspond to each memory type such as a read-only type, a write-once type, and a rewritable type. Therefore, as a method for realizing an inexpensive large-capacity file, application to a wide range of uses from industrial use to consumer use is considered.
[0003]
Among them, digital audio disks (DAD), optical video disks, and the like, which are optical disks corresponding to a read-only memory type, are widely used at present.
[0004]
An optical disk such as a digital audio disk has a reflective film made of a metal thin film such as an aluminum (Al) film on a light-transmitting disk substrate on which a concavo-convex pattern such as pits or grooves indicating information signals is formed. The reflective film is coated with the moisture (H ₂ O) and oxygen (O ₂ ) And a protective film for protection from the When reproducing the information signal on the optical disk, the disk substrate irradiates a reproduction light such as a laser beam toward the concave / convex pattern, and detects the information signal based on a difference in reflectance between incident light and return light by the reproduction light. I do.
[0005]
When manufacturing such an optical disk, first, a disk substrate having a concavo-convex pattern is formed by an injection molding method. Next, a reflective film made of a metal thin film is formed on the optical disk substrate by a vacuum evaporation method. Next, a protective film is formed by applying an ultraviolet curable resin on the upper layer of the reflective film.
[0006]
In recent years, in such an optical information recording system, further higher recording density has been required. In order to respond to the demand for higher recording density, a technique for reducing the spot diameter of the reproduction light by increasing the numerical aperture (NA) of the objective lens used when irradiating the reproduction light with the optical pickup. Was suggested.
[0007]
That is, for example, while the NA of an objective lens used for reproducing a conventional DAD is 0.45, an optical video disk such as a DVD (Digital Versatile Disc) having a recording capacity 6 to 8 times that of the conventional DAD. In this case, the spot diameter is reduced by setting the NA of the objective lens used for reproduction to about 0.60.
[0008]
As the NA of such an objective lens is increased, it becomes necessary to make the disk substrate of the optical disk thinner in order to transmit the irradiated reproduction light. This is because the tolerance of the angle (tilt angle) deviating from the perpendicular of the disk surface with respect to the optical axis of the optical pickup is reduced, and the tilt angle is affected by aberration and birefringence due to the thickness of the disk substrate. This is because it is easy to receive. Therefore, the tilt angle is made as small as possible by making the disk substrate thinner. For example, in the above-mentioned DAD, the thickness of the substrate is about 1.2 mm. On the other hand, in an optical video disc such as a DVD having a recording capacity of 6 to 8 times that of the DAD, the thickness of the substrate is about 0.6 mm.
[0009]
In view of the demand for higher recording density in the future, it is necessary to further reduce the thickness of the substrate. Therefore, an information signal portion is formed by forming irregularities on one main surface of the substrate, and a reflection film and a light transmission layer made of a thin film capable of transmitting light are sequentially laminated on the information signal portion, and the light transmission layer side is formed. There has been proposed an optical disc configured to reproduce an information signal by irradiating a reproduction light from the optical disc. In such an optical disc that reproduces an information signal by irradiating reproduction light from the light transmission layer side, it is possible to cope with a high NA of the objective lens by reducing the thickness of the light transmission layer. .
[0010]
However, as the thickness of the light transmitting layer is reduced, it becomes difficult to form the light transmitting layer by an injection molding method using a thermoplastic resin, which is generally used for manufacturing an optical disk. That is, it is very difficult to form a light-transmitting layer of about 0.1 mm that maintains good transparency while maintaining low birefringence by employing the conventional technique.
[0011]
Therefore, a method of forming the light transmitting layer from an ultraviolet curable resin has been devised. However, when the light transmitting layer is formed of an ultraviolet curable resin, it is very difficult to make the light transmitting layer uniform on the substrate surface. Therefore, it becomes difficult to stably reproduce the information signal.
[0012]
Therefore, a method has been proposed in which a light-transmitting sheet is attached to a disk substrate with an adhesive to form a light-transmitting layer having small birefringence, good transparency, and a uniform film thickness. For example, a light-transmitting sheet in which an adhesive layer made of a pressure-sensitive adhesive is provided on one main surface of a flat stage made of metal and a pad made of an elastic body provided at a position facing the flat stage, There has been proposed a method in which a signal portion presses a disk substrate provided on one main surface and bonds a light-transmitting sheet to the disk substrate. According to this method, for example, a light-transmitting layer having a small birefringence, good transparency, and a uniform thickness of 0.1 mm can be formed.
[0013]
[Problems to be solved by the invention]
However, in the optical disk formed by the above-described method, the adhesive layer made of the pressure-sensitive adhesive is exposed to the air at the inner peripheral edge and the outer peripheral edge. When the adhesive layer is exposed to the air in this way, not only does the appearance of the optical disc deteriorate, but also the following important problems occur.
[0014]
That is, (1) the light-transmitting layer may be peeled off from the substrate when the part of the adhesive layer exposed to the air comes into contact with a projection or the like. There is a problem in that foreign substances such as dust are adsorbed, and (3) in long-term use, the information signal portion is corroded through a portion of the adhesive layer exposed to the atmosphere.
[0015]
Therefore, an object of the present invention is to provide an optical recording medium capable of preventing a light transmitting layer from being peeled off from a substrate when a portion of an adhesive layer exposed to the air comes into contact with a projection or the like, and a method of manufacturing the same. Is to do.
[0016]
Another object of the present invention is to provide an optical recording medium capable of preventing foreign substances such as dust from adsorbing to a portion of an adhesive layer exposed to the air, and a method of manufacturing the same.
[0017]
Still another object of the present invention is to provide an optical recording medium capable of preventing the information signal portion from being corroded through a portion of the adhesive layer exposed to the atmosphere during long-term use, and a method of manufacturing the same. It is in.
[0018]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, a first invention of the present application provides an information recording / reproducing apparatus capable of recording and / or reproducing an information signal by irradiating a laser beam onto one main surface of a substrate having an opening at a central portion. A signal portion, and a protective layer that covers at least the information signal portion;
A protective layer, a sheet having an opening in the center, and an optical recording medium characterized by comprising an adhesive layer for bonding the sheet to one main surface of the substrate,
An inner peripheral sealing portion that covers at least a portion where the adhesive layer comes into contact with the atmosphere in the inner peripheral portion of the protective layer and / or an outer peripheral sealing portion that covers at least a portion where the adhesive layer comes into contact with the air at the outer peripheral portion of the protective layer is provided. An optical recording medium characterized by the following.
[0019]
In the first invention of the present application, typically, the protective layer is a light transmitting layer configured to transmit a laser beam used for recording and / or reproducing an information signal.
[0020]
In the first invention of the present application, typically, the moisture permeability of the inner sealing portion and the outer sealing portion is 0.1 g / cm. ² ・ 75g / cm over 24h ² ・ It is 24 hours or less. In the first invention of the present application, typically, the residual chlorine ion concentration in the inner sealing portion and the outer sealing portion is 0.01 ppm or more and 1.0 ppm or less.
[0021]
In the first invention of this application, typically, the inner sealing portion and the outer sealing portion are made of an ultraviolet curable resin. In the first invention of this application, typically, the inner peripheral sealing portion rises from the surface on the side where the protective layer is provided. In the first invention of the present application, typically, the swelling width of the sealing portion is 0.1 mm or more and 1.2 mm or less based on the surface on the side where the protective layer is provided.
[0022]
In the first invention of the present application, typically, the substrate and the protective layer have an annular shape, and the diameter of the protective layer is smaller than the diameter of the substrate. In the first invention of the present application, typically, the substrate and the protective layer have an annular shape, and the diameter of the protective layer is equal to the diameter of the substrate. In the first invention of the present application, typically, the openings of the substrate and the protective layer have a circular shape, and the diameter of the opening of the protective layer is larger than the diameter of the opening of the substrate.
[0023]
The second invention of the present application is a step of forming an information signal portion for recording and / or reproducing an information signal by irradiating a laser beam onto one main surface of a substrate having an opening in a central portion;
A step of forming a protective layer on the information signal portion by covering at least the information signal portion and bonding a sheet having an opening in the center with an adhesive layer,
A step of forming an inner peripheral enclosing portion that covers at least a portion of the protective layer where the adhesive layer comes into contact with the atmosphere and / or a peripheral enclosing portion that covers at least an outer peripheral portion of the protective layer where the adhesive layer comes into contact with the atmosphere; When
A method for manufacturing an optical recording medium, comprising:
[0024]
In the second invention of the present application, typically, the moisture permeability of the sealed portion is 0.1 g / cm. ² ・ 75g / cm over 24h ² ・ It is 24 hours or less. In the second invention of the present application, typically, the residual chloride ion concentration in the sealed portion is 0.01 ppm or more and 1.0 ppm or less.
[0025]
The second invention of the present application is typically a light transmission layer in which the protective layer is configured to transmit a laser beam used for recording and / or reproduction of an information signal.
[0026]
In the second invention of the present application, typically, an ultraviolet curable resin is applied so as to cover at least a portion where the adhesive layer comes into contact with the atmosphere in the inner peripheral portion of the protective layer, and the applied ultraviolet curable resin is irradiated with ultraviolet light. To form an inner peripheral enclosure.
[0027]
In the second invention of this application, typically, the surface tension of the ultraviolet curable resin is from 20 mN / m to 40 mN / m.
[0028]
In the second invention of the present application, typically, the openings of the substrate and the sheet are circular. Typically, the second invention of the present application rotates the substrate on which the protective layer is formed on one main surface, and drops the ultraviolet-curable resin from above the inner peripheral portion of the protective layer, thereby removing the ultraviolet-curable resin. Apply. In the second invention of the present application, typically, an ultraviolet curable resin is dropped by a dispenser.
[0029]
In the second invention of the present application, typically, an ultraviolet curable resin is applied so as to cover at least a portion where the adhesive layer comes into contact with the atmosphere at the outer peripheral portion of the protective layer, and the applied ultraviolet curable resin is irradiated with ultraviolet light. By curing, an outer peripheral sealing portion is formed.
[0030]
In the second invention of the present application, typically, the surface tension of the ultraviolet curable resin has a value of 20 mN / m or more and 40 mN / m or less.
[0031]
In the second invention of this application, the substrate and the sheet are typically circular. The second invention of the present application typically applies the ultraviolet-curable resin by rotating the substrate on which the protective layer is formed on one main surface and dropping the ultraviolet-curable resin from above the outer periphery of the protective layer. I do. In the second invention of the present application, typically, an ultraviolet curable resin is dropped by a dispenser.
[0032]
The second invention of the present application typically provides a resin supply unit that supplies an ultraviolet-curable resin by contact at least to a portion of the protective layer where the adhesive layer comes into contact with the atmosphere at an outer peripheral portion, so that the ultraviolet-curable resin is Apply.
[0033]
Typically, the second invention of the present application is to rotate the substrate on which the protective layer is formed on one main surface, and to adhere to the liquid surface of the ultraviolet curable resin stored in the resin supply means at the outer peripheral portion of the protective layer. The ultraviolet curable resin is applied by bringing at least a portion where the layer comes into contact with the atmosphere.
[0034]
In the present invention, in order to minimize warpage and distortion in the manufactured optical recording medium, the light transmitting sheet is preferably made of the same material as the material used for the substrate. The thickness of the light-transmitting sheet is typically configured to be smaller than the thickness of the substrate, and is specifically selected from 30 μm or more and 150 μm or less. In the present invention, the disc substrate is made of a low water-absorbing resin such as polycarbonate (PC) or cycloolefin polymer. Preferably, the light-transmitting sheet is made of the same material as the disc substrate. Is done. As a material used for the substrate, for example, a substrate made of a metal such as aluminum (Al), a glass substrate, or a substrate made of a resin such as polyolefin, polyimide, polyamide, polyphenylene sulfide, or polyethylene terephthalate (PET) is used. It is also possible.
[0035]
In the present invention, typically, the light-transmitting sheet is a GaN-based semiconductor laser (emission wavelength of 400 nm band, blue light emission) or a ZnSe-based semiconductor laser (emission wavelength of 500 nm band, which is used at least for recording / reproduction of information signals. A non-magnetic material capable of transmitting laser light emitted from an AlGaInP-based semiconductor laser (emission wavelength: about 635 to 680 nm, red) or the like, specifically, a heat-transmissive material such as polycarbonate. It is made of a plastic resin. In the present invention, the protective sheet is preferably made of polyethylene terephthalate (PET), polyethylene naphthalate (PEN), or the like. Specifically, at least one surface of the PET or PEN is coated with a second adhesive. Is being worn. Then, the surface to which the second pressure-sensitive adhesive is applied is adhered to one surface of the light-transmitting sheet, thereby forming a sheet to be bonded to the substrate.
[0036]
The present invention can be suitably applied to a next-generation optical recording medium having a thin light transmitting layer such as a DVR (Digital Video Recording system), and uses a semiconductor laser having an emission wavelength of about 650 nm to transmit an information signal. Optical recording such as so-called DVR-red configured to perform recording and reproduction, and so-called DVR-blue configured to perform recording and reproduction of information signals using a semiconductor laser having an emission wavelength of about 400 nm. It can be applied to media. This DVR is preferably configured such that an information signal can be recorded using an objective lens whose NA has been increased to about 0.85. An optical recording medium to which the present invention is preferably applied, such as the DVR, is preferably housed in a cartridge, but the application of the present invention is not necessarily limited to the one housed in a cartridge.
[0037]
In the optical recording medium according to the first aspect of the present invention, a portion of the adhesive layer which comes into contact with the atmosphere is provided on the outer peripheral portion and / or the inner peripheral portion of the protective layer including the sheet and the adhesive layer formed on the information signal portion of the substrate. Since at least the enclosing portion for covering is provided, it is possible to prevent the adhesive layer from being exposed to the air at the outer peripheral portion and / or the inner peripheral portion of the optical recording medium. Therefore, when the portion of the adhesive layer exposed to the air comes into contact with the protrusion or the like, the protective layer can be prevented from peeling off from the substrate. In addition, it is possible to prevent a foreign substance such as dust from adsorbing to a portion of the adhesive layer exposed to the atmosphere. Further, it is possible to prevent the information signal portion from being corroded through the portion of the adhesive layer exposed to the air during long-term use.
[0038]
In the method of manufacturing an optical recording medium according to the second aspect of the present invention, an information signal portion for recording and / or reproducing an information signal is formed on one main surface of a substrate having an opening at a central portion by irradiating a laser beam. Then, a protective layer is formed on the information signal portion by bonding a sheet having an opening in the center with an adhesive layer at least covering the information signal portion, and the adhesive layer is formed on the inner peripheral portion and / or the outer peripheral portion of the protective layer. Since the sealing portion that covers the portion that comes into contact with the atmosphere is formed, it is possible to prevent the light transmitting layer from being exposed to the atmosphere at the outer peripheral portion and / or the inner peripheral portion of the optical recording medium. Therefore, when the portion of the adhesive layer exposed to the air comes into contact with the protrusion or the like, the protective layer can be prevented from peeling off from the substrate. In addition, it is possible to prevent a foreign substance such as dust from adsorbing to a portion of the adhesive layer exposed to the atmosphere. Further, it is possible to prevent the information signal portion from being corroded through the portion of the adhesive layer exposed to the air during long-term use.
[0039]
BEST MODE FOR CARRYING OUT THE INVENTION
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.
[0040]
First, an optical disc according to the first embodiment of the present invention will be described. FIG. 1 shows an example of the configuration of the optical disc according to the first embodiment. FIG. 2 shows an example of the configuration of the disk substrate according to the first embodiment. FIG. 3 shows an example of the configuration of the sheet according to the first embodiment.
[0041]
As shown in FIG. 1, the optical disk according to the first embodiment mainly includes an annular disk substrate 1 having a center hole 1b in the center and a planar annular light having a through hole 2c in the center. The light transmitting layer 2 includes an inner peripheral sealing portion 3 a provided on the inner peripheral side wall of the light transmitting layer 2 and an outer peripheral sealing portion 3 b provided on the outer peripheral side wall of the light transmitting layer 2.
[0042]
As shown in FIG. 1, a clamp area 4 for mounting the optical disk on the spindle motor is set near the center hole 1b of the optical disk. The inner diameter of the clamp area 4 is selected from 22 mm to 24 mm, for example, 23 mm. The outer diameter of the clamp area 4 is selected from 32 mm to 34 mm, for example, 33 mm.
[0043]
As shown in FIG. 2, the disk substrate 1 has a center hole 1b at the center and a replica substrate 1a having irregularities formed on one main surface, and an information signal formed on one main surface of the replica substrate 1a. 1c.
[0044]
The thickness of the replica substrate 1a is selected from 0.6 mm to 1.2 mm, for example, 1.1 mm. The diameter (outer diameter) of the replica substrate 1a is, for example, 120 mm, and the opening diameter (inner diameter) of the center hole 1b is, for example, 15 mm. As the material of the replica substrate 1a, a low water-absorbing resin such as polycarbonate (PC) or cycloolefin polymer (for example, ZEONEX (registered trademark)) is used. The optical disc according to the first embodiment is configured to record / reproduce information signals by irradiating the disc substrate 1 with laser light from the side where the thin light transmitting layer 2 is provided. I have. Therefore, since it is not necessary to consider whether or not the replica substrate 1a has transparency, it is also possible to use a substrate made of a metal such as Al, for example. Further, as the replica substrate 1a, a glass substrate or a substrate made of a resin such as polyolefin, polyimide, polyamide, polyphenylene sulfide, or polyethylene terephthalate can be used.
[0045]
The information signal section 1c is provided with a reflective film, a film made of a magneto-optical material, a film made of a phase change material, an organic dye film, or the like. Among them, as a material of the reflection film, for example, Al or an Al alloy is used. Specifically, when the optical disc as a final product is a read-only type (ROM (Read Only Memory)) optical disc, the information signal unit 1c has at least a reflective layer made of, for example, Al, an Al alloy, or an Ag alloy. It is configured by providing a single-layer film or a laminated film. On the other hand, when the optical disc as a final product is a rewritable optical disc, the information signal portion 1c is made of a film made of a magneto-optical material such as a TbFeCo-based alloy, a TbFeCoSi-based alloy, or a TbFeCoCr-based alloy, a GeSbTe alloy, a GeInSbTe. A single-layer film or a laminated film having at least a film made of an alloy or a phase change material such as an AgInSbTe alloy is provided. When the optical disc as the final product is a write-once optical disc, the information signal portion 1c is formed of a film made of a phase change material such as a GeTe material or a film made of an organic dye material such as a cyanine dye or a phthalocyanine dye. It is composed of at least a single layer film or a laminated film.
[0046]
Here, in the case where the optical disc is of a rewritable type, an example of a specific configuration of the information signal section 1c is as follows. The information signal section 1c has a thickness of, for example, over a region of the replica substrate 1a where the unevenness is formed. A reflective layer made of an Al alloy having a thickness of 100 nm and having a thickness of, for example, 18 nm, zinc sulfide (ZnS) and silicon oxide (SiO 2) ₂ (ZnS-SiO) ₂ ), A phase change recording layer made of a GeSbTe alloy having a thickness of, for example, 24 nm, and a ZnS-SiO film having a thickness of, for example, 100 nm. ₂ Is a laminated film in which a second dielectric layer made of
[0047]
As shown in FIG. 3, a sheet 5 used for forming the light transmitting layer 2 according to the first embodiment includes a light transmitting sheet 2a and a pressure-sensitive adhesive applied to one surface of the light transmitting sheet 2a. And an adhesive layer 2b made of an agent (PSA). This sheet 5 has a structure punched out in a plane annular shape, as in the disk substrate 1, and has a through hole 2c formed in the center. The diameter (outer diameter) of the sheet 5 is selected to be substantially the same as or smaller than the outer diameter of the disk substrate 1, and is, for example, 120 mm. On the other hand, the diameter (diameter of the inner hole) of the through hole 2c is selected from a range not less than the opening diameter of the center hole 1b and not more than the innermost diameter of the clamp region 4 (diameter of 23 mm, for example). The thickness of the sheet 5 is, for example, 100 μm.
[0048]
The light-transmitting sheet 2a of the sheet 5 is made of, for example, a light-transmitting thermoplastic resin that satisfies at least optical characteristics capable of transmitting laser light used for recording / reproducing. The thermoplastic resin is selected from materials having physical properties such as heat-resistant dimensional stability, coefficient of thermal expansion, or coefficient of hygroscopic expansion close to the replica substrate 1a. Specifically, for example, polycarbonate (PC), polymethyl methacrylate ( Methacrylic resin such as poly (methyl methacrylate). Further, the thickness of the light transmitting sheet 2a is preferably selected from the range of 60 μm to 100 μm, and more preferably selected from the range of 70 μm to 100 μm. In the first embodiment, considering that the light-transmitting sheet 2a is bonded to one main surface of the disc substrate 1 via the adhesive layer 2b made of a pressure-sensitive adhesive (PSA), The thickness of the sheet 2a is selected to be, for example, 70 μm. The thickness of the light transmitting sheet 2a is determined in consideration of the wavelength of laser light used for recording / reproducing information signals and the desired thickness of the light transmitting layer 2.
[0049]
The PSA forming the adhesive layer 2b is, for example, methacrylic resin. The thickness of the adhesive layer 2b is, for example, 30 μm, but the thickness of the adhesive layer 2b and the material used as the pressure-sensitive adhesive include the desired film thickness of the light transmitting layer 2 and the recording of information signals. / Determined in consideration of the wavelength of laser light used for reproduction. Although not shown, when the sheet 5 is stored, the surface of the adhesive layer 2b of the sheet 5 is laminated with a protective film for protecting the sheet.
[0050]
FIG. 4A is an enlarged sectional view of the inner peripheral portion of the optical disc according to the first embodiment of the present invention. The inner peripheral sealing portion 3a provided on the inner peripheral side wall of the light transmitting layer 2 preferably covers at least the inner peripheral side wall of the adhesive layer 2b, preferably the inner peripheral side wall of the light transmitting layer 2. It is formed so that it may cover.
[0051]
The width d of the inner peripheral sealing portion 3a ₁ Is selected from 0.1 mm to 2.0 mm, for example, 0.8 mm. The height h of the inner peripheral sealing portion 3a is selected from 0.05 mm to 0.5 mm, for example, 0.1 mm.
[0052]
FIG. 4B is an enlarged sectional view of the outer peripheral portion of the optical disc according to the first embodiment of the present invention. As shown in FIG. 4B, the outer peripheral sealing portion 3b provided on the outer peripheral side wall of the optical disk covers at least the outer peripheral side wall of the adhesive layer 2b, and preferably covers the outer peripheral side wall of the optical disk. Is formed. The thickness d of the outer enclosing portion 3b ₂ Is selected from 0.05 mm to 0.2 mm, for example, 0.1 mm.
[0053]
The inner peripheral enclosing portion 3a and the outer peripheral enclosing portion 3b are made of, for example, an ultraviolet curing resin. The moisture permeability of the inner peripheral enclosing part 3a and the outer peripheral enclosing part 3b is, for example, 0.1 g / cm in an environment of a temperature of 40 ° C. and a humidity of 90%. ² ・ 24h-75g / cm ² ・ Selected from the range of 24h. Further, the residual ion concentration is selected from the range of 0.01 ppm to 0.1 ppm.
[0054]
Next, a method for manufacturing the optical disk according to the first embodiment configured as described above will be described. FIG. 5 is a flowchart for explaining an example of the method of manufacturing the optical disc according to the first embodiment.
[0055]
First, in step ST1, a replica substrate 1a having irregularities formed on one principal surface is manufactured by, for example, an injection molding method.
[0056]
Next, in step ST2, the information signal portion 1c is formed on one main surface of the replica substrate 1a where the unevenness is formed. Specifically, for example, when the optical disc as a final product is a read-only optical disc, Al, an Al alloy or an aluminum alloy is formed on one main surface of the replica substrate 1a on which the irregularities are formed, for example, by a vacuum evaporation method or a sputtering method. A reflective layer made of an Ag alloy or the like is formed. Thus, the disk substrate 1 shown in FIG. 2 is manufactured.
[0057]
Next, in step ST3, the sheet 5 is bonded to one main surface of the disk substrate 1 on which the information signal portion 1c is formed.
[0058]
Hereinafter, the step of bonding the disk substrate 1 and the sheet 5 will be specifically described with reference to FIG. First, the disk substrate 1 is mounted at a predetermined position on a disk mounting surface (not shown) of the disk mounting plate. Here, the optical disk mounting surface is flat. Then, the sheet 5 is held so as to be inclined with respect to the disk substrate 1 so that the clearance between the sheet 5 and the disk substrate 1 gradually increases from one end of the sheet 5 to the other end. Thereafter, as shown by an arrow a in FIG. 6, the roll 10 around which the elastic body is wound is moved from one end of the disk substrate 1 to the other end. Thus, the sheets 5 are sequentially bonded to the disk substrate 1 from one end of the disk substrate 1 to the other end. The clearance between the sheet 5 and the disk substrate 1 is maintained until immediately before the other end of the sheet 5 is bonded.
[0059]
Thereby, as shown in FIG. 7, the light transmitting layer 2 is formed on one main surface of the disk substrate 1 on which the information signal portion 1c is formed.
[0060]
Next, in step ST4, the inner peripheral enclosing portion 3a and the outer peripheral enclosing portion 3b are formed on the disk substrate 1 on which the light transmitting layer 2 is formed.
[0061]
Hereinafter, with reference to FIGS. 8 and 9, a process of forming the encapsulating portion will be specifically described. First, as shown in FIG. 8, in step ST3, the disk substrate 1 on which the light transmitting layer 2 is formed on one main surface is rotated, and an ultraviolet curable resin is formed on the outer peripheral side walls of the disk substrate 1 and the light transmitting layer 2. The supply unit 11 is brought into contact, and the ultraviolet curable resin is uniformly applied. Then, ultraviolet rays are applied to the ultraviolet curing resin applied to the outer peripheral portions of the disk substrate 1 and the light transmitting layer 2. Thereby, as shown in FIG. 4B, the uniform thickness d is formed on the outer peripheral side walls of the disk substrate 1 and the light transmitting layer 2. ₂ Is formed.
[0062]
Next, while keeping the rotation of the disk substrate 1, the dispenser 12 is moved to a position where the ultraviolet curing resin can be applied to the inner side wall of the light transmitting layer 2. Then, as shown in FIG. 9, the ultraviolet curable resin is dropped, and the ultraviolet curable resin is uniformly applied to the inner peripheral side wall of the light transmitting layer 2. Thereafter, ultraviolet rays are applied to the ultraviolet curable resin applied to the outer peripheral side wall of the light transmitting layer 2. Thereby, as shown in FIG. 4A, the uniform thickness d is formed on the inner side wall of the light transmitting layer 2. ₁ Is formed.
[0063]
In order to apply a desired amount of the ultraviolet curable resin to a desired position on the optical disk, the surface tension of the ultraviolet curable resin in a liquid state is preferably 20 mN / m to 40 mN / m. If the lower limit of the surface tension is set to 20 mN / m or less, it is difficult to apply the ultraviolet curable resin only to a desired portion because the viscosity is too low. On the other hand, if the upper limit of the surface tension is set to 40 mN / m or more, the wettability deteriorates, and it becomes difficult to apply a desired amount of the ultraviolet curable resin to the optical disk.
[0064]
In addition, the present inventor has studied the moisture permeability range of the sealed part in order to further improve the corrosion prevention effect of the sealed part. The moisture permeability range was examined as follows.
[0065]
First, Sample A, Sample B, Sample C, and Sample D having the same configuration as the optical disk according to the first embodiment and having different moisture permeability of the ultraviolet component resin forming the outer peripheral sealing portion were manufactured. In addition, the thickness d of the outer peripheral sealing portion of these samples ₂ Is 0.1 mm. The residual ion concentration of the ultraviolet curable resin is 1 ppm. Here, the study range of the moisture permeability is 1 g / cm. ² ・ 24h-100g / cm ² ・ It is 24h. This moisture permeability is measured by maintaining a 100 μm thick sheet-shaped sample made of an ultraviolet curable resin in an environment of a temperature of 40 ° C. and a humidity of 90% for 24 hours.
[0066]
After performing an acceleration test for each sample for 200 hours in an environment of a temperature of 80 ° C. and a humidity of 85%, the outer peripheral region of the information signal portion is visually observed to determine whether the outer peripheral portion is corroded. It was determined whether or not.
[0067]
Table 1 shows the moisture permeability of each sample and the determination result. In Table 1, when no corrosion is observed in the outer peripheral region of the sample, the determination result is represented by O, and when corrosion is observed in the outer peripheral region of the sample, the determination result is represented by X.
[0068]
[Table 1]

[0069]
From Table 1, the moisture permeability is 75 g / cm. ² In the sample having a sealed portion exceeding 24 hours, corrosion was observed in the outer peripheral region, whereas the moisture permeability was 75 g / cm. ² -No corrosion was observed in the outer peripheral region of the sample having the sealed portion of 24 hours or less. That is, the moisture permeability of the sealed portion is 75 g / cm ² By setting the length to 24 hours or less, the effect of preventing corrosion of the sealed portion can be further improved.
[0070]
Furthermore, the present inventor studied the residual chlorine ion concentration range of the sealed portion in order to further improve the corrosion prevention effect of the sealed portion. The examination of the residual chlorine ion concentration range was performed as follows.
[0071]
First, Sample F, Sample G, Sample H, and Sample I having the same configuration as the optical disk according to the first embodiment, and having different chlorine ion concentrations in the ultraviolet constituent resin constituting the outer peripheral sealing portion were manufactured. In addition, the thickness d of the outer peripheral sealing portion of these samples ₂ Is 0.1 mm. The moisture permeability of the ultraviolet curable resin is 75 g / cm. ² ・ It is 24h. This moisture permeability is measured by maintaining a 100 μm thick sheet-shaped sample made of an ultraviolet curable resin in an environment of a temperature of 40 ° C. and a humidity of 90% for 24 hours. Here, the examination range of the chloride ion concentration is in the range of 0.1 to 1.5 ppm, and the value of the chloride ion concentration is measured by an ion chromatograph.
[0072]
After performing an acceleration test on each sample for 200 hours in an environment of a temperature of 80 ° C. and a humidity of 85%, the outer peripheral region of the information signal portion is visually observed, and corrosion occurs on the outer peripheral portion of the optical disk. Was determined.
[0073]
Table 2 shows the chloride ion concentration of each sample and the determination results. In Table 2, when no corrosion was observed in the outer peripheral region of the sample, the determination result was represented by ○, and when corrosion was observed in the outer peripheral region of the sample, the determination result was represented by ×.
[0074]
[Table 2]

[0075]
From Table 2, it was found that corrosion was observed in the outer peripheral region in the sample having the sealed portion having the moisture permeability exceeding 1.0 ppm, whereas the sample having the sealed portion having the chlorine ion concentration of 1.0 ppm or less was observed. No corrosion was observed in the outer peripheral region. That is, the effect of preventing corrosion can be further improved by setting the chlorine ion concentration in the sealed portion to 1.0 ppm or less.
[0076]
According to the first embodiment of the present invention, the following effects can be obtained.
An inner sealing portion 3a and an outer sealing portion 3b that cover at least a portion where the adhesive layer 2b comes into contact with the atmosphere are formed on the inner circumferential side surface and the outer circumferential side surface of the light transmitting layer 2 of the optical disc. 2b can be prevented from contacting the atmosphere. Therefore, the portion of the adhesive layer 2b exposed to the air does not come into contact with the protrusion or the like, and the light transmitting layer 2 can be prevented from peeling off from the disk substrate 1. In addition, it is possible to prevent foreign matter such as dust from adsorbing to the portion of the adhesive layer 2b exposed to the atmosphere. Further, it is possible to prevent the information signal portion from being corroded through the portion of the adhesive layer 2b exposed to the air during long-term use.
[0077]
Further, by forming the inner peripheral enclosing portion 3a and the outer peripheral enclosing portion 3b using an ultraviolet curable resin having a surface tension in a liquid state of the ultraviolet curable resin of 20 mN / m to 40 mN / m, a desired position of the optical disc , A desired amount of an ultraviolet curable resin can be applied. Therefore, workability in the enclosing portion forming step can be further improved.
[0078]
Further, the moisture permeability of the inner peripheral sealing portion 3a and the outer peripheral sealing portion 3b is set to 0.1 g / cm. ² ・ 24h-75g / cm ² By setting the length to 24 h, the effect of preventing corrosion by the inner enclosing portion 3a and the outer enclosing portion 3b can be further improved.
[0079]
In addition, by setting the residual chlorine ion concentration of the inner sealing portion 3a and the outer sealing portion 3b to 0.01 ppm to 1.0 ppm, the effect of preventing corrosion by the inner sealing portion 3a and the outer sealing portion 3b is further improved. Can be.
[0080]
Next, a second embodiment of the present invention will be described. The configuration of the optical disc according to the second embodiment of the present invention is the same as that of the optical disc according to the first embodiment, and thus the description is omitted.
[0081]
Hereinafter, a method of manufacturing the optical disc according to the second embodiment of the present invention will be described. In the method for manufacturing an optical disk according to the second embodiment, the steps from the replica substrate forming step (step ST1) to the bonding step (step ST3) are substantially the same as those in the first embodiment, and thus description thereof will be omitted.
[0082]
FIG. 10 is a view for explaining an enclosing portion forming step according to the second embodiment of the present invention. First, the light transmitting layer 2 was formed such that one main surface of the disk substrate 1 on which the light transmitting layer 2 was formed was perpendicular to the liquid surface of the ultraviolet curing resin 6 stored in the supply unit 13. The disk substrate 1 is held above the supply unit 13.
[0083]
Next, the disk substrate 1 on which the light transmission layer 2 is formed is rotated, and the disk substrate 1 on which the light transmission layer 2 is formed is moved to the supply unit 13 by the side walls of the disk substrate 1 and the outer periphery of the light transmission layer 2. Is moved to a position where it comes into contact with the liquid surface of the ultraviolet curable resin 6 stored therein. At this time, one main surface of the disk substrate 1 is held perpendicular to the liquid surface of the ultraviolet curable resin 6 stored in the supply unit 13. Thereby, the ultraviolet curable resin 6 is uniformly applied to the outer peripheral side walls of the disk substrate 1 and the light transmitting layer 2.
[0084]
Thereafter, the disk substrate 1 is separated from the liquid surface of the ultraviolet curable resin 6 stored in the supply unit 13, and ultraviolet rays are applied to the ultraviolet curable resin 6 applied to the disk substrate 1 and the outer peripheral side wall of the light transmitting layer 2. Thereby, the ultraviolet curable resin 6 applied to the outer peripheral side walls of the disk substrate 1 and the light transmitting layer 2 is cured, and the outer peripheral enclosing portion 3b is formed.
[0085]
The rest of the procedure is the same as in the first embodiment, and a description thereof will be omitted.
[0086]
According to the second embodiment of the present invention, the same effects as those of the first embodiment can be obtained.
[0087]
Next, a third embodiment of the present invention will be described. FIG. 11 is a sectional view showing an example of the configuration of the optical disc according to the third embodiment of the present invention.
[0088]
As shown in FIG. 11, the light transmitting layer 2 has an outer diameter smaller than the disk substrate 1. The light transmission layer 2 has, for example, an outer diameter 0.2 mm to 1.0 mm smaller than the disk substrate 1. Here, the diameter (outer diameter) of the disk substrate 1 is, for example, 120 mm. The outer enclosing portion 3b is formed on one main surface of the disc substrate 1 so as to cover at least the inner side wall of the adhesive layer 2a, and preferably to cover the inner side wall of the light transmitting layer 2. You.
[0089]
The other points are the same as those of the optical disk according to the first embodiment, and thus the description is omitted.
[0090]
Next, a method for manufacturing the optical disc according to the third embodiment of the present invention will be described. In the method for manufacturing an optical disk according to the third embodiment, the steps from the replica substrate forming step (step ST1) to the bonding step (step ST3) are substantially the same as those in the first embodiment, and thus description thereof will be omitted.
[0091]
FIG. 12 shows an example of the disk substrate 1 formed by the steps ST1 to ST3 and having the light transmitting layer 2 formed on one main surface.
[0092]
Hereinafter, the encapsulation portion forming step will be described with reference to FIGS. First, while rotating the disk substrate 1 on which the light transmitting layer 2 is formed on one main surface, the inner peripheral dispenser 14 is positioned such that the tip of the inner peripheral dispenser 14 is located above the inner peripheral portion of the light transmitting layer 2. The inner peripheral dispenser 15 is moved so that the tip of the outer peripheral dispenser 15 is located above the outer peripheral portion of the light transmitting layer 2.
[0093]
Then, ultraviolet curable resin is dropped from the inner peripheral dispenser 14 and the outer peripheral dispenser 15. Thereby, the ultraviolet curable resin having a uniform thickness is applied to the inner side wall of the light transmitting layer 2, and the ultraviolet curable resin having a uniform thickness is applied to the outer side wall of the light transmitting layer 2. .
[0094]
Finally, the ultraviolet curing resin applied to the inner and outer peripheral portions of the optical disk is irradiated with ultraviolet rays. As a result, the ultraviolet curable resin applied to the inner and outer peripheral portions of the optical disk is cured, and the inner and outer enclosing portions 3a and 3b are formed. Specifically, a uniform thickness d is formed on the inner side wall of the light transmitting layer 2. ₁ Is formed on the outer peripheral side wall of the light transmitting layer 2 with a uniform thickness d. ₂ Is formed. Thus, the desired optical disk is manufactured.
[0095]
The subsequent steps are the same as those of the manufacturing method according to the above-described first embodiment, and a description thereof will not be repeated.
[0096]
According to the third embodiment of the present invention, the same effects as in the first embodiment can be obtained.
[0097]
Although the embodiments of the present invention have been specifically described above, the present invention is not limited to the above embodiments, and various modifications based on the technical idea of the present invention are possible.
[0098]
For example, the numerical values given in the above embodiment are merely examples, and different numerical values may be used as needed.
[0099]
In the first, second, and third embodiments described above, the inner peripheral sealing portion 3a may be raised from the surface on which the light transmitting layer 2 is provided.
[0100]
FIG. 15 shows an inner peripheral portion of an optical disc provided with an inner peripheral enclosing portion 3a having a shape rising from the surface on which the light transmitting layer 2 is provided. The raised width H of the inner peripheral sealing portion 3a is 0.1 mm or more and 2.0 mm or less, for example, 1.2 mm, based on the surface of the optical disk on which the light transmitting layer 2 is provided. Accordingly, when a plurality of optical disks are stacked, a stack rib for preventing the stacked disks from contacting each other can be formed.
[0101]
In the first, second, and third embodiments described above, the disk substrate 1 and the sheet 5 may be bonded in a vacuum. Thereby, the mixing of bubbles can be further reduced, and the effect of preventing the mixing of bubbles can be further improved. Therefore, it has a thin, thin, small birefringent, light-transmitting layer with good transparency and uniform thickness, and has high reliability that can support a high NA of the objective lens. Optical discs can be manufactured.
[0102]
Further, in the first and second embodiments described above, an example has been described in which the ultraviolet curable resin is applied to the outer peripheral portion, and then the ultraviolet curable resin is applied to the inner peripheral portion. However, the present invention is not limited to this embodiment. For example, an ultraviolet curable resin may be applied simultaneously to the inner peripheral portion and the outer peripheral portion. Further, after the ultraviolet curable resin is applied to the inner peripheral portion, the ultraviolet curable resin may be applied to the outer peripheral portion.
[0103]
Further, in the third embodiment of the present invention, the example in which the ultraviolet curable resin is applied simultaneously to the outer peripheral portion and the outer peripheral portion has been described, but the method of applying the ultraviolet curable resin is not limited to this embodiment. is not. For example, after the ultraviolet curable resin is applied to the inner peripheral portion, the ultraviolet curable resin may be applied to the outer peripheral portion. Alternatively, after the ultraviolet curable resin is applied to the outer peripheral portion, the ultraviolet curable resin may be applied to the inner peripheral portion.
[0104]
【The invention's effect】
As described above, according to the present invention, it is possible to prevent the protective layer from peeling off from the substrate when the portion of the adhesive layer exposed to the air comes into contact with the protrusion or the like. That is, it is possible to prevent the durability of the optical recording medium from being improved.
[0105]
Further, according to the present invention, it is possible to prevent the information signal portion from being corroded through the portion of the adhesive layer exposed to the atmosphere during long-term use. That is, the durability of the optical recording medium can be improved.
[Brief description of the drawings]
FIG. 1 is a sectional view showing an example of a configuration of an optical disc according to a first embodiment of the present invention.
FIG. 2 is a sectional view showing an example of a configuration of the disk substrate according to the first embodiment of the present invention.
FIG. 3 is a cross-sectional view illustrating an example of a configuration of a sheet according to the first embodiment of the present invention.
FIG. 4 is an enlarged cross-sectional view of an inner peripheral portion and an outer peripheral portion of the optical disc according to the first embodiment of the present invention.
FIG. 5 is a flowchart for explaining a method of manufacturing the optical disc according to the first embodiment of the present invention.
FIG. 6 is a perspective view of a disk substrate and a sheet for explaining a bonding step according to the first embodiment of the present invention.
FIG. 7 is a cross-sectional view of a disk substrate having a light transmitting layer formed on one principal surface in a bonding step according to the first embodiment of the present invention.
FIG. 8 is a schematic diagram for explaining an enclosing portion forming step according to the first embodiment of the present invention.
FIG. 9 is a schematic diagram for explaining an enclosing portion forming step according to the first embodiment of the present invention.
FIG. 10 is a schematic diagram for explaining an enclosing portion forming step according to a second embodiment of the present invention.
FIG. 11 is a sectional view showing an example of a configuration of an optical disc according to a third embodiment of the present invention.
FIG. 12 is a cross-sectional view of a disk substrate having a light transmitting layer formed on one principal surface in a bonding step according to a third embodiment of the present invention.
FIG. 13 is a schematic diagram for explaining an enclosing portion forming step according to a third embodiment of the present invention.
FIG. 14 is a cross-sectional view of an outer peripheral portion of an optical disc for describing an enclosing portion forming step according to a third embodiment of the present invention.
FIG. 15 is a cross-sectional view showing an example of an optical disk configuration according to a modification of the first, second, or third embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Disk substrate, 1a ... Replica substrate, 1b ... Center hole, 1c ... Information signal part, 2 ... Light transmission layer, 2a ... Light transmission sheet, 2b ... Adhesive layer, 2c: through hole, 3a: outer peripheral sealing portion, 3b: outer peripheral sealing portion, 4: clamp region, 5: sheet, 10: roll, 11: ultraviolet light Cured resin supply unit, 12: dispenser, 13: supply unit, 14: inner peripheral dispenser, 15: outer peripheral dispenser

Claims (26)

An information signal portion configured to be able to record and / or reproduce an information signal by irradiating a laser beam onto one main surface of a substrate having an opening in a central portion, and a protective layer covering at least the information signal portion. Prepare,
The protective layer, a sheet having an opening in the center, an optical recording medium characterized by comprising an adhesive layer for bonding the sheet to one main surface of the substrate,
An inner sealing portion that covers at least a portion of the protective layer where the adhesive layer contacts the atmosphere and / or an outer sealing portion that covers at least a portion of the outer layer of the protective layer where the adhesive layer contacts the atmosphere. An optical recording medium comprising: 2. The optical recording medium according to claim 1, wherein the protective layer is a light transmitting layer configured to transmit a laser beam used for recording and / or reproducing the information signal. The optical recording medium of claim 1, wherein the moisture permeability of the inner peripheral sealed part and the peripheral sealed portion is not more than 0.1g ^/ cm 2 · 24h or more 75g ^/ cm 2 · 24h. 2. The optical recording medium according to claim 1, wherein a residual chlorine ion concentration of the inner peripheral sealing portion and the outer peripheral sealing portion is 0.01 ppm or more and 1.0 ppm or less. 2. The optical recording medium according to claim 1, wherein the inner sealing portion and the outer sealing portion are made of an ultraviolet curable resin. 2. The optical recording medium according to claim 1, wherein the inner peripheral sealing portion rises from a surface on a side where the protective layer is provided. 7. The optical recording medium according to claim 6, wherein a swelling width of the enclosing portion is 0.1 mm or more and 1.2 mm or less based on a surface on which the protective layer is provided. The substrate and the protective layer have an annular shape,
2. The optical recording medium according to claim 1, wherein the diameter of the protective layer is smaller than the diameter of the substrate. The substrate and the protective layer have an annular shape,
2. The optical recording medium according to claim 1, wherein the diameter of the protective layer is equal to the diameter of the substrate. 2. The optical recording medium according to claim 1, wherein the openings of the substrate and the protective layer have a circular shape, and the diameter of the opening of the protective layer is larger than the diameter of the opening of the substrate. Forming an information signal portion for recording and / or reproducing an information signal by irradiating a laser beam to one main surface of the substrate having an opening in the center;
A step of forming a protective layer on the information signal portion by covering at least the information signal portion and bonding a sheet having an opening in the center with an adhesive layer,
An inner sealing portion that covers at least a portion of the protective layer where the adhesive layer contacts the atmosphere and / or an outer sealing portion that covers at least a portion of the outer layer of the protective layer where the adhesive layer contacts the atmosphere. Forming an optical recording medium. Method of producing an optical recording medium according to claim 11, wherein the moisture permeability of the enclosure is less than 0.1g ^/ cm 2 · 24h or more 75g ^/ cm 2 · 24h. The method for manufacturing an optical recording medium according to claim 11, wherein the residual chlorine ion concentration in the sealed portion is 0.01 ppm or more and 1.0 ppm or less. The method of manufacturing an optical recording medium according to claim 11, wherein the protective layer is a light transmitting layer configured to transmit a laser beam used for recording and / or reproducing the information signal. An ultraviolet curable resin is applied so as to cover at least a portion where the adhesive layer comes into contact with the air at an inner peripheral portion of the protective layer, and the applied ultraviolet curable resin is cured by irradiating ultraviolet rays to the inner peripheral portion. The method for manufacturing an optical recording medium according to claim 11, wherein an enclosing portion is formed. The method for manufacturing an optical recording medium according to claim 15, wherein the surface tension of the ultraviolet curable resin is 20 mN / m or more and 40 mN / m or less. The method for manufacturing an optical recording medium according to claim 15, wherein the openings of the substrate and the sheet are circular. The method according to claim 1, further comprising: applying the ultraviolet curable resin by rotating the substrate on which the protective layer is formed on one main surface and dropping the ultraviolet curable resin from above the inner peripheral portion of the protective layer. Item 18. The method for producing an optical recording medium according to Item 17. 19. The method for manufacturing an optical recording medium according to claim 18, wherein the ultraviolet curable resin is dropped by a dispenser. An ultraviolet curable resin is applied so as to cover at least a portion where the adhesive layer comes into contact with the atmosphere in an outer peripheral portion of the protective layer, and the applied ultraviolet curable resin is cured by irradiating ultraviolet rays to cure the outer peripheral enclosing portion. The method of manufacturing an optical recording medium according to claim 11, wherein: 21. The method for manufacturing an optical recording medium according to claim 20, wherein the surface tension of the ultraviolet curable resin is from 20 mN / m to 40 mN / m. 21. The method according to claim 20, wherein the substrate and the sheet are circular. The UV curable resin is applied by rotating the substrate on which the protective layer is formed on one main surface and dropping the UV curable resin from above the outer peripheral portion of the protective layer. 23. The method for producing an optical recording medium according to 22. The method for manufacturing an optical recording medium according to claim 23, wherein the ultraviolet curable resin is dropped by a dispenser. The ultraviolet-curable resin is applied by bringing a resin supply unit that supplies the ultraviolet-curable resin into contact with at least a portion of the outer periphery of the protective layer where the adhesive layer comes into contact with the atmosphere. 21. The method for producing an optical recording medium according to 20. Along with rotating the substrate on which the protective layer is formed on one main surface, a portion of the outer peripheral portion of the protective layer where the adhesive layer comes into contact with the air is provided on the liquid surface of the ultraviolet curable resin stored in the resin supply means. 21. The method for manufacturing an optical recording medium according to claim 20, wherein the ultraviolet curable resin is applied by at least bringing the resin into contact.

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