JP2006228278A - Optical disk - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical disk capable of accurately recording desired visible images, which is the optical disk provided with an image recording layer on a label surface. <P>SOLUTION: The optical disk is composed by providing an information recording layer or an information recording part, a reflection layer, the image recording layer where the visible images are to be recorded by irradiation with a laser beam, a barrier layer, and a transparent protective layer on a substrate in the order. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an optical disc capable of recording a visible image on a label surface (surface opposite to the recording surface).

  Conventionally, an optical disc (optical disc) capable of recording information only once by laser light is known. This optical disk is also called a recordable CD (so-called CD-R), and its typical structure is a recording layer made of an organic dye on a transparent disk-shaped substrate, a light reflecting layer made of a metal such as gold, and a resin. A protective layer made of a metal is provided in this order in a laminated state. Information recording on this CD-R is performed by irradiating the CD-R with a near-infrared laser beam (usually a laser beam having a wavelength near 780 nm), and the irradiated portion of the recording layer emits the light. Information is recorded by absorbing and locally raising the temperature, causing a physical or chemical change (eg, pit generation) and changing its optical properties. On the other hand, reading (reproduction) of information is also performed by irradiating a laser beam having the same wavelength as that of the recording laser beam. Information is reproduced by detecting the difference in reflectance from (part).

  In recent years, optical discs with higher recording density have been demanded. In response to such a demand, an optical disk called a recordable digital vasatile disk (so-called DVD-R) has been proposed. This DVD-R is formed so that the guide groove (pre-groove) spacing (track pitch) for tracking the irradiated laser beam is less than half (0.74 to 0.8 μm) compared to the CD-R. Two discs having a recording layer made of a dye on a transparent disc-shaped substrate, and usually a light reflecting layer on the recording layer, and further a protective layer if necessary, or the same shape as the disc It has a structure in which a disk-shaped protective substrate is bonded with an adhesive with the recording layer inside. Information recording / reproduction on a DVD-R is performed by irradiating visible laser light (usually laser light having a wavelength in the range of 630 nm to 680 nm), and recording at a higher density than CD-R is possible. Has been.

  By the way, in the various optical discs described above, the music title of the music data recorded on the recording surface and the recorded data are identified on the surface (label surface) opposite to the recording surface on which the music data is recorded. There is known a label on which visible information such as a title is attached. Such an optical disc is produced by printing a title or the like on a circular label sheet in advance by a printer or the like and sticking the label sheet on the label surface of the optical disc.

  As described above, when an optical disc in which a desired visible image such as a title is recorded on the label surface is manufactured, a printer is required separately from the optical disc drive. Therefore, after recording on a recording surface of an optical disk using an optical disk drive, the optical disk is taken out from the optical disk drive, and a label sheet printed by a separately prepared printer as described above is attached. Need to do work. In addition, the method of applying a label sheet peels off during use due to durability problems such as adhesives, and the unbalance during rotation of the optical disk increases due to misalignment during lamination, resulting in recording and playback. May not be possible.

In view of this, an optical recording medium has been proposed in which a laser marker is used on the label surface and the contrast between the surface and the background can be changed (for example, see Patent Document 1). Such a recording medium can perform desired image recording on the label surface of the optical disk by an optical disk drive without separately preparing a printer or the like. However, the optical recording medium described in Patent Document 1 has low sensitivity, and a high-power gas laser such as a carbon dioxide gas laser must be used, and a visible image formed by the laser light as described above has a contrast. Was low and inferior in visibility.
On the other hand, a recording medium having a visible information recording layer capable of recording visible information with a laser beam has been proposed (see, for example, Patent Document 2). This recording medium has a laser light transmission layer on the visible information recording layer, and can form a visible image without adversely affecting the medium and electronic information recorded on the medium by low-power laser irradiation. Has characteristics.

In the recording medium described in Patent Document 2 having such a configuration, the laser light transmission layer is directly provided on the visible information recording layer by a coating method, but the visible information recording layer is a layer containing a dye. In this case, since the dye and the laser light transmission layer coating solution are in direct contact with each other, the solvent in the coating solution reacts with the dye, and as a result, the dye in the visible image forming layer may be deteriorated. . Thus, when the pigment | dye in a visible image formation layer deteriorates, the sensitivity to a laser beam will be produced, and it had the problem that it became difficult to form a desired visible image.
JP-A-11-66617 JP 2004-103180 A

This invention is made | formed in view of the above conventional trouble, and makes it a subject to achieve the following objectives. That is,
An object of the present invention is to provide an optical disc having an image recording layer (visible information recording layer) on a label surface and capable of accurately recording a desired visible image.

Means for solving the problems are as follows. That is,
The optical disc of the present invention has an information recording layer or information recording portion, a reflective layer, an image recording layer on which a visible image is recorded by irradiation with laser light, a barrier layer, and a transparent protective layer in this order on a substrate. It is characterized by that.
In the optical disk of the present invention, the transparent protective layer includes an aspect composed of a transparent adhesive layer or a transparent adhesive layer and a transparent cover sheet, and an aspect composed of a transparent curable resin layer.

Further, the optical disk of the present invention preferably includes the following four embodiments having the following layer configurations (1) to (4).
(1) Configuration in which an information recording layer, an information recording reflective layer, a protective layer, an adhesive layer, a protective layer, an image recording reflective layer, an image recording layer, a barrier layer, and a transparent protective layer are sequentially provided on a substrate ( 2) Configuration having an information recording layer, an information recording reflective layer, an adhesive layer, an image recording reflective layer, an image recording layer, a barrier layer, and a transparent protective layer in this order on the substrate. (3) Information on the substrate. Configuration having recording layer, reflective layer for information recording, adhesive layer, protective layer, reflective layer for image recording, image recording layer, barrier layer, and transparent protective layer in sequence (4) Information recording layer, information on substrate Structure having a reflective layer for recording, a protective layer, an adhesive layer, a reflective layer for image recording, an image recording layer, a barrier layer, and a transparent protective layer in this order

  ADVANTAGE OF THE INVENTION According to this invention, it is an optical disk provided with the image recording layer on the label surface, Comprising: An optical disk which can record a desired visible image accurately can be provided.

The optical disk of the present invention will be described below.
The optical disc of the present invention has an information recording layer or information recording portion, a reflective layer, an image recording layer on which a visible image is recorded by irradiation with laser light, a barrier layer, and a transparent protective layer in this order on a substrate. It is characterized by that.
In other words, the optical disc of the present invention has a CD-ROM, CD-R, and CR-RW CD-based recording medium that the information recording layer or information recording portion and the reflective layer have in this order on the substrate. An image recording layer, a barrier layer, and a transparent protective layer, which function to form the film, are provided in this order.

The optical disk of the present invention has a write-once type, rewritable type having an information recording layer capable of recording and reproducing information by laser light, and an information recording part (recording pit) in which information reproducible by laser light is recorded. Any of a reproduction-only (read-only) type may be used, but a write-once type is preferable.
The information recording format is not particularly limited, such as a phase change type, a dye type, and a write-once type, but is preferably a dye type.

A configuration example of the optical disk of the present invention will be described below with reference to FIG. Here, FIG. 1 is a schematic cross-sectional view of an essential part showing a configuration example of the optical disk of the present invention.
As shown in FIG. 1A, an optical disc 100a of the present invention has an information recording layer 20, a reflective layer 30, an image recording layer 40, and a barrier layer 50 in this order on a substrate 10, and further includes a barrier. On the layer 50, a protective layer 60 composed of a transparent adhesive layer or transparent adhesive layer 62 and a transparent cover sheet 64 is provided.
Further, as shown in FIG. 1B, the optical disc 100b of the present invention has an information recording layer 20, a reflective layer 30, an image recording layer 40, and a barrier layer 50 in this order on a substrate 10. The protective layer 60 is made of a transparent curable resin layer 66 on the barrier layer 50.

In the optical disc 100a of the present invention, the information recording layer 20, the reflective layer 30, the image recording layer 40, and the barrier layer 50 are sequentially provided on the substrate 10, and then the transparent cover sheet 64 is formed by the transparent adhesive layer or the transparent adhesive layer 62. It can be manufactured by bonding.
The optical disc 100b of the present invention can be manufactured by sequentially providing the information recording layer 20, the reflective layer 30, the image recording layer 40, the barrier layer 50, and the transparent curable resin layer 66 on the substrate 10. it can.

In addition to the layer configuration of the optical discs 100a and 100b as described above, for example, the following configurations are also included.
(1) Configuration in which an information recording layer, an information recording reflective layer, a protective layer, an adhesive layer, a protective layer, an image recording reflective layer, an image recording layer, a barrier layer, and a transparent protective layer are sequentially provided on a substrate ( 2) Configuration having an information recording layer, an information recording reflective layer, an adhesive layer, an image recording reflective layer, an image recording layer, a barrier layer, and a transparent protective layer in this order on the substrate. (3) Information on the substrate. Configuration having recording layer, reflective layer for information recording, adhesive layer, protective layer, reflective layer for image recording, image recording layer, barrier layer, and transparent protective layer in sequence (4) Information recording layer, information on substrate Structure having a reflective layer for recording, a protective layer, an adhesive layer, a reflective layer for image recording, an image recording layer, a barrier layer, and a transparent protective layer in this order

The optical disc of the present invention having the layer configuration of the above (1) to (4) can be produced as follows.
First, at least an information recording layer and an information recording reflective layer are sequentially provided on a substrate to form a first laminate. In addition, a second laminate having at least a reflective layer for image recording, an image recording layer, a barrier layer, and a transparent protective layer is formed. The first laminated body and the second laminated body are bonded to each other with an adhesive layer with both reflective layers inside, thereby producing an optical disk having the layer configuration of (1) to (4).
When the second laminate has a protective layer adjacent to the reflective layer for image recording, the reflective layer for image recording, the image recording layer, the barrier layer, and the transparent protective layer are provided on the protective layer. It may be formed by sequentially providing layers, and a barrier layer, an image recording layer, and a reflective layer for image recording (and, if necessary, a protective layer) are sequentially provided on the transparent protective layer. May be formed.

In such an optical disc of the present invention, it is essential that a transparent protective layer is provided on the surface of the image recording layer via a barrier layer. Due to the presence of this barrier layer, when the transparent protective layer is formed, the dye in the image recording layer does not come into contact with the coating liquid for the transparent protective layer, so that deterioration of the dye can be prevented. Further, according to this configuration, the image recording layer is chemically and physically protected by the transparent protective layer. Therefore, a desired visible image can be accurately formed on the image recording layer in the optical disc of the present invention.
Hereafter, each element which comprises the optical disk of this invention is demonstrated in order.
Each layer constituting the optical disc of the present invention may be composed of one layer or a plurality of layers.

[substrate]
The substrate can be arbitrarily selected from various materials used as substrates for conventional optical disks.
Examples of substrate materials include acrylic resins such as glass, polycarbonate, and polymethyl methacrylate, vinyl chloride resins such as polyvinyl chloride and vinyl chloride copolymers, epoxy resins, amorphous polyolefins, and polyesters. You may use them together. Among the above materials, polycarbonate is preferable from the viewpoint of moisture resistance, dimensional stability, price, and the like.
In general, the thickness of the substrate is preferably 1.2 ± 0.2 mm, more preferably 1.2 ± 0.1 mm, and above all, it functions to form a visible image. In consideration of the thickness of the image recording layer, the barrier layer, and the transparent protective layer, the thickness may be appropriately determined within the range of 0.5 to 1.4 mm.

Further, the substrate is provided with unevenness (pre-groove) representing information such as a guide groove for tracking or an address signal.
Specifically, the track pitch of the pregroove formed on the substrate is preferably in the range of 1.2 to 2.0 μm, more preferably 1.4 to 1.8 μm, More preferably, it is 1.65 μm.
The pregroove depth (groove depth) is preferably in the range of 100 to 250 nm, more preferably 150 to 230 nm, and even more preferably 170 to 210 nm.
Furthermore, the half width of the pregroove is preferably in the range of 400 to 650 nm, more preferably 480 to 600 nm, and even more preferably 500 to 580 nm.

  Further, the light incident surface of the substrate in the present invention may be provided with a hard coat layer for preventing the light incident surface from being damaged when the optical disk is manufactured or used.

In the substrate of the present invention, on the surface of the substrate on which the information recording layer is provided (the surface side on which the pregroove is formed), for the purpose of improving flatness, improving adhesion, and preventing deterioration of the information recording layer, An undercoat layer may be provided.
Examples of the material for the undercoat layer include polymethyl methacrylate, acrylic acid / methacrylic acid copolymer, styrene / maleic anhydride copolymer, polyvinyl alcohol, N-methylol acrylamide, styrene / vinyl toluene copolymer, chlorosulfone. Polymer materials such as chlorinated polyethylene, nitrocellulose, polyvinyl chloride, chlorinated polyolefin, polyester, polyimide, vinyl acetate / vinyl chloride copolymer, ethylene / vinyl acetate copolymer, polyethylene, polypropylene, polycarbonate; and silane coupling And a surface modifier such as an agent. The undercoat layer is formed by dissolving or dispersing the above substances in a suitable solvent to prepare a coating solution, and then applying this coating solution to the substrate surface by a coating method such as spin coating, dip coating, or extrusion coating. can do.
The thickness of the undercoat layer is generally in the range of 0.005 to 20 μm, preferably in the range of 0.01 to 10 μm.

  When the optical disc of the present invention is a read-only type, an information recording portion on which information that can be reproduced by laser light is recorded is provided as a recording pit on the substrate. In this embodiment, the information recording layer is not formed.

[Information recording layer]
The information recording layer is a layer in which code information (encoded information) such as digital information is recorded, and includes a dye type (recordable type), a phase change type, and the like. Is preferred.

Specific examples of the dye contained in the dye-type information recording layer include a cyanine dye, an oxonol dye, a metal complex dye, an azo dye, and a phthalocyanine dye. Of these, oxonol dyes are particularly preferable.
JP-A-4-74690, JP-A-8-127174, 11-53758, 11-334204, 11-334205, 11-334206, 11-334207 No. 2000, 43423, 2000-108513, 2000-158818, and the like are preferably used.
Furthermore, the dye-type information recording layer includes triazole compounds, triazine compounds, cyanine compounds, merocyanine compounds, aminobutadiene compounds, phthalocyanine compounds, cinnamic acid compounds, viologen compounds, azo compounds, oxonol benzoxazole compounds, benzotriazole compounds, etc. These organic compounds are also preferably used. Among these compounds, cyanine compounds, aminobutadiene compounds, benzotriazole compounds, and phthalocyanine compounds are particularly preferable.

  A leuco dye can also be used. Specifically, crystal violet lactone; 3,3-bis (1-ethyl-2-methylindol-3-yl) phthalide, 3- (4-diethylamino-2-ethoxyphenyl) -3- (1-ethyl 2- Phthalide compounds such as methylindol-3-yl) -4-azaphthalide; 3-cyclohexylmethylamino-6-methyl-7-anilinofluorane, 2- (2-chloroanilino) -6-dibutylaminofluorane, 3- Diethylamino-6-methyl-7-anilinofluorane, 3-diethylamino-6-methyl-7-xylidinofluorane, 2- (2-chloroanilino) -6-diethylaminofluorane, 2-anilino-3-methyl- 6 (N-ethylisopentylamino) fluorane, 3-diethylamino-6-chloro-7-anilinofluor Down, 3-benzyl-ethyl-6-methyl-7-anilinofluoran, fluoran compounds such as 3-methyl-propyl-6-methyl-7-anilinofluoran; and the like are preferable.

The dye-type information recording layer can be formed by a method such as vapor deposition, sputtering, CVD, or solvent coating, but solvent coating is preferred.
When solvent coating is used, the dye-type information recording layer prepares a coating solution by dissolving a recording material such as a dye in a solvent together with a quencher, a binder, etc., and then coats this coating solution on a substrate. After forming a coating film, it is formed by drying. The concentration of the recording substance (dye) in the coating liquid is generally in the range of 0.01 to 15% by mass, preferably in the range of 0.1 to 10% by mass, more preferably in the range of 0.5 to 5% by mass. The most preferable range is 0.5 to 3% by mass.

Examples of the solvent of the coating solution include esters such as butyl acetate, ethyl lactate and cellosolve acetate; ketones such as methyl ethyl ketone, cyclohexanone and methyl isobutyl ketone; chlorinated hydrocarbons such as dichloromethane, 1,2-dichloroethane and chloroform; dimethylformamide and the like Amides; Hydrocarbons such as methylcyclohexane; Ethers such as dibutyl ether, diethyl ether, tetrahydrofuran, dioxane; Alcohols such as ethanol, n-propanol, isopropanol, n-butanol, diacetone alcohol; 2,2,3,3-tetra Fluorinated solvents such as fluoropropanol; ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, propylene glycol monomethyl ether, etc. And the like can be mentioned recall ethers.
The said solvent can be used individually or in combination of 2 or more types in consideration of the solubility of the pigment | dye to be used. Various additives such as an antioxidant, a UV absorber, a plasticizer, and a lubricant may be further added to the coating solution depending on the purpose.

  When a binder is used, examples include natural organic polymer materials such as gelatin, cellulose derivatives, dextran, rosin and rubber; and hydrocarbon resins such as polyethylene, polypropylene, polystyrene and polyisobutylene; polyvinyl chloride, Vinyl resins such as polyvinylidene chloride and polyvinyl chloride / polyvinyl acetate copolymers; acrylic resins such as polymethyl acrylate and polymethyl methacrylate; polyvinyl alcohol, chlorinated polyethylene, epoxy resins, butyral resins, rubber derivatives, Examples thereof include synthetic organic polymers such as initial condensates of thermosetting resins such as phenol / formaldehyde resins.

  When a binder is used in combination as a material for the dye-type information recording layer, the amount of binder used is generally in the range of 0.01 to 50 times the mass of the dye, preferably 0.1 to It is in the range of 5 times the amount.

Examples of the solvent application method include a spray method, a spin coating method, a dip method, a roll coating method, a blade coating method, a doctor roll method, and a screen printing method.
The layer thickness of the dye-type information recording layer is generally in the range of 10 to 500 nm, preferably in the range of 15 to 300 nm, and more preferably in the range of 20 to 150 nm.
The dye-type information recording layer may be composed of a single layer or a multilayer.

  The dye-type information recording layer can contain various anti-fading agents in order to improve the light resistance. As the anti-fading agent, a singlet oxygen quencher is generally used. As the singlet oxygen quencher, those described in publications such as known patent specifications can be used. Specific examples thereof include JP-A Nos. 58-175893, 59-31194, 60-18387, 60-19586, 60-19588, 60-35054, 60-36190, 60-36191, 60-44554, 60-44555, 60-44389, 60-44390, 60-54892, 60-47069, 68-209995, JP Listed in publications such as Nos. 4-25492, 1-38680, and 6-26028, German Patent No. 350399, and the Chemical Society of Japan, October 1992, page 1141 Can do.

  The amount of the anti-fading agent such as the singlet oxygen quencher used is usually in the range of 0.1 to 50% by mass, preferably in the range of 0.5 to 45% by mass, more preferably , In the range of 3 to 40% by mass, particularly preferably in the range of 5 to 25% by mass.

Specific examples of the material constituting the phase change information recording layer include Sb—Te alloy, Ge—Sb—Te alloy, Pd—Ge—Sb—Te alloy, Nb—Ge—Sb—Te alloy, Pd. -Nb-Ge-Sb-Te alloy, Pt-Ge-Sb-Te alloy, Co-Ge-Sb-Te alloy, In-Sb-Te alloy, Ag-In-Sb-Te alloy, Ag-V-In- Sb—Te alloy, Ag—Ge—In—Sb—Te alloy, and the like can be given. Among these, Ge—Sb—Te alloy and Ag—In—Sb—Te alloy are preferable because they can be rewritten many times.
The layer thickness of the phase change information recording layer is preferably 10 to 50 nm, and more preferably 15 to 30 nm.
Such a phase change type information recording layer can be formed by a vapor phase thin film deposition method such as a sputtering method or a vacuum deposition method.

[Reflective layer]
The reflection layer is provided between the information recording layer and the image recording layer in order to achieve the purpose of improving the reflectance during information reproduction and / or the purpose of improving the visibility of the visible image. That is, as shown in FIG. 1, the reflective layer in the present invention is provided with only one layer between the information recording layer and the image recording layer, and may be shared for information recording and image recording. Further, as in the layer configurations (1) to (4) above, a reflective layer for recording information and a reflective layer for recording images may be provided separately.
As described above, when the reflective layer formed by only one layer between the information recording layer and the image recording layer is shared by both recording layers, the reflective layer for information recording and the image recording are separately provided. Compared to the case, there is an advantage that the cost (manufacturing cost) related to film formation can be reduced and the manufacturing process can be reduced.
On the other hand, when the reflective layer for recording information and the reflective layer for recording image are provided separately, an adhesive layer is provided to bond the two reflective layers together. As shown in FIG. 1, the unevenness of the pregroove provided on the substrate is not reflected in the reflective layer for the image recording layer, and as a result, the image visibility can be improved. Has advantages.

The light-reflective substance which is a material of such a reflective layer is a substance having a high reflectance with respect to laser light, and examples thereof include Mg, Se, Y, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Re, Fe, Co, Ni, Ru, Rh, Pd, Ir, Pt, Cu, Ag, Au, Zn, Cd, Al, Ga, In, Si, Ge, Te, Pb, Po, Examples thereof include metals such as Sn and Bi, metalloids, stainless steel, and semiconductor materials. These substances may be used alone or in combination of two or more or as an alloy. Among these, Cr, Ni, Pt, Cu, Ag, Au, Al, and stainless steel are preferable. More preferred is Au, Ag, Al or an alloy thereof, still more preferred is Ag, Al or an alloy thereof, and most preferred is an Ag alloy (Ag—Nd—Cu, Ag—Pd—Cu, Ag). -In-Cu, Ag-Bi-Nd).
In the case where the reflective layer for recording information and the reflective layer for recording image are provided separately, it is possible to appropriately select a material for optimizing the characteristics of each recording layer. The viewpoint in that case is reflectance, thermal conductivity, cost, surface smoothness, corrosion resistance, visibility, and the like.

The reflective layer can be formed on the information recording layer or the image recording layer, for example, by vapor deposition, sputtering or ion plating of the light reflecting material.
The thickness of the reflective layer is generally in the range of 10 to 300 nm, and preferably in the range of 50 to 200 nm. When only one reflective layer is provided (when a single reflective layer is used for both information recording and image recording), a range of 50 to 500 nm is preferable, and a range of 80 to 300 nm is more preferable. On the other hand, when providing the reflective layer for information recording and the reflective layer for image recording separately, the range of 10-200 nm is preferable and the range of 50-150 nm is more preferable.

[Adhesive layer]
The adhesive layer in the optical disc of the present invention is formed by attaching both reflective layers when the reflective layer for recording information and the reflective layer for recording image are provided separately as in the layer configurations (1) to (4) above. It is a layer for matching.
As a material constituting the adhesive layer, a UV curable resin may be used, or a synthetic adhesive may be used. Examples of the synthetic adhesive include a slow-acting adhesive such as a cationic curable epoxy resin and a spin-curable adhesive such as an ultraviolet curable acrylate resin.
Among these, it is preferable to use a slow-acting adhesive. This is done by forming a coating film of a slow-acting adhesive in advance on at least one of the bonding surfaces of the first laminate and the second laminate and irradiating the coating with ultraviolet rays. It is because it can do. Thereby, it becomes possible to bond together with high precision. Examples of the slow-acting adhesive include the above-mentioned cationic curable epoxy resin, and specifically, SK7000 manufactured by Sony Chemical Corporation can be used.

These adhesives are applied to at least one bonding surface by a method such as roll coating, spin coating, or screen printing. Then, the adhesive is cured to form an adhesive layer.
The thickness of the formed adhesive layer is preferably in the range of 10 to 100 μm, more preferably in the range of 20 to 60 μm, from the viewpoint of adhesive strength and leveling effect.

[Protective layer]
The protective layer in the present invention is provided for the purpose of physically and chemically protecting the reflective layer for information recording and / or the reflective layer for image recording as in the layer configurations of (1) to (4) above. Any layer.
When a slow-acting adhesive is used when adhering the first laminate and the second laminate, screen printing is often used for applying the slow-acting adhesive, and air bubbles enter the coating film. There is. It is conceivable that the bubbles may adversely affect the characteristics (for example, jitter and visibility) of minute recording pits when in contact with the reflective layer for information recording or image recording. In addition, silver, a silver alloy, aluminum, or the like is often used as a reflective layer for information recording or image recording, and some adhesives constituting the adhesive layer may corrode these metals.
Therefore, in order to prevent the influence of bubbles on the reflective layer and the corrosion of the metal in the reflective layer, the protective layer is provided between the reflective layer for information recording and / or the reflective layer for image recording and the adhesive layer. Is preferably provided.
In particular, by forming a protective layer that does not contain bubbles, the influence of bubbles in the adhesive layer on the reflective layer can be eliminated. Further, by selecting an ultraviolet curable resin that does not corrode the reflective layer (for example, SD640 manufactured by DIC) as the protective layer, corrosion and deterioration of the metal in the reflective layer can be prevented.

  When the adhesive layer can be formed by a method that does not include bubbles (for example, spin coating or double-sided adhesive tape), the protective layer can be omitted. Also, the protective layer can be omitted as appropriate even when the materials constituting the reflective layer for information recording and the reflective layer for image recording do not cause a deterioration reaction with the adhesive. Furthermore, when bubbles in the adhesive layer do not significantly affect the image, the protective layer between the adhesive layer and the image recording reflective layer may be omitted.

Examples of materials used for the protective layer include inorganic substances such as ZnS, ZnS—SiO ₂ , SiO, SiO ₂ , MgF ₂ , SnO ₂ , and Si ₃ N ₄ , thermoplastic resins, thermosetting resins, and UV curable materials. Organic substances such as resins can be mentioned.
The protective layer can be formed, for example, by laminating a film obtained by extrusion of plastic on an information recording reflective layer and / or an image recording reflective layer via an adhesive.
Further, as the protective layer, a film obtained by extrusion of plastic is used, and a reflective layer for image recording, an image recording layer, a barrier layer, and a transparent protective layer are provided on the film, and the above-described second lamination is performed. You may form a body.
Moreover, you may provide by methods, such as vacuum evaporation, sputtering, and application | coating.

Furthermore, when forming a protective layer using a thermoplastic resin or a thermosetting resin, it is also possible to prepare a coating solution by dissolving these in an appropriate solvent, and then apply this coating solution and dry it. Can be formed. In the case of a UV curable resin, it can also be formed by applying this coating solution and curing it by irradiation with UV light. In these coating liquids, various additives such as an antistatic agent, an antioxidant and a UV absorber may be further added according to the purpose.
The layer thickness of the protective layer is generally in the range of 0.1 μm to 1 mm.

[Image recording layer]
The image recording layer is provided adjacent to the reflective layer and the reflective layer for image recording. Visible images (visible information) desired by the user, such as characters, graphics, and patterns, are recorded on the image recording layer by laser light. Examples of visible images include disc titles, content information, content thumbnails, related patterns, design patterns, copyright information, recording date, recording method, recording format, barcodes, and the like.

  Here, the visible image recorded in the image recording layer means a visually recognizable image, and includes all visually recognizable information such as characters (columns), designs, and figures. Also, as character information, usable person designation information, use period designation information, usable number designation information, rental information, resolution designation information, layer designation information, user designation information, copyright holder information, copyright number information, manufacturing Information, manufacturer date information, sale date information, dealer or seller information, use set number information, region designation information, language designation information, application designation information, product user information, use number information, and the like.

  The image recording layer only needs to be able to record image information such as letters, images, and patterns by laser irradiation so that the recording material (pigment or phase change) described in the information recording layer described above can be used. Recording material) can be preferably used, but from the viewpoint of visibility, a layer containing a dye is preferable.

Further, in the optical disc of the present invention, the information recording layer component (recording substance: dye or phase change recording material) described above and the image recording layer component may be the same or different. Since the required characteristics are different between the image recording layer and the image recording layer, it is preferable to make the constituent components different. Specifically, the constituent components of the information recording layer are preferably excellent in recording / reproducing characteristics, and the constituent components of the image recording layer are preferably those in which the contrast of the recorded visible image is high.
In particular, in the case of using a dye as a constituent component of the image recording layer, from the viewpoint of improving the contrast of a recorded image, among the dyes described above, a cyanine dye, a phthalocyanine dye, an azo dye, an azo metal complex, an oxonol dye, It is preferable to use a leuco dye.
Further, one of the information recording layer and the image recording layer may be a phase change type and the other may be a dye type. In this case, the information recording layer is preferably a phase change type and the image recording layer is preferably a dye type.

  The image recording layer can be formed by preparing a coating solution by dissolving the above-described dye in a solvent and coating the coating solution. As the solvent, the same solvent as that used for preparing the coating solution for the information recording layer described above can be used. Other additives and coating methods can also be performed in the same manner as the information recording layer described above.

  The thickness of the image recording layer is preferably in the range of 0.01 to 200 μm, more preferably in the range of 0.05 to 20 μm, and still more preferably in the range of 0.1 to 5 μm.

  A tracking guide groove may be formed on the laser light incident surface of the image recording layer. The guide groove is formed so as to follow the shape of the pregroove formed in the substrate 10 as shown in FIGS. When the guide groove is formed in the image recording layer as described above, the image can be recorded with the laser pickup being tracked, and the position of the pickup can be precisely controlled, so that a precise image can be recorded. Can do. Further, by providing grooves in the image recording layer, there is an effect that light interferes and the surface looks like a beautiful rainbow color.

[Barrier layer]
The main purpose of the barrier layer is to prevent the deterioration of the dye in the information recording layer that occurs during the formation of the protective layer, which will be described later, and further to improve the storage stability of the image recording layer. It is provided for improving adhesion, adjusting reflectance, adjusting thermal conductivity, and the like.
The material used for the barrier layer is not particularly limited as long as it is a material that transmits a laser beam for recording an image on the image recording layer and can exhibit the above functions. For example, in general, it is a material having low gas and moisture permeability, and is preferably a dielectric. Here, the barrier layer preferably has a transmittance of 80% or more, more preferably a transmittance of 90% or more, and further preferably a transmission with respect to a laser beam for recording an image on the image recording layer. The rate is 95% or more.

Specifically, the material used for the barrier layer is preferably a material made of nitride, oxide, carbide or sulfide of Zn, Si, Ti, Te, Sn, Mo, Ge, etc., and ZnS, MoO ₂ , GeO _{2, TeO, SiO 2, TiO} 2, ZuO, preferably _{ZnS-SiO 2, SnO 2,} ZnO-Ga 2 O 3, ZnS-SiO 2, SnO 2, ZnO-Ga 2 O 3 is more preferable.

The barrier layer can be formed on the recording layer by a vacuum film forming method such as vacuum deposition, DC sputtering, RF sputtering, or ion plating. The film forming conditions in these vacuum film forming methods can be appropriately adjusted according to the film forming material, the desired film thickness, film density, and the like.
The thickness of the barrier layer is preferably in the range of 1 to 200 nm, more preferably in the range of 2 to 100 nm, and still more preferably in the range of 3 to 70 nm.

[Transparent protective layer]
The transparent protective layer is provided for the purpose of physically and chemically protecting the image forming layer. Note that “transparent” in the transparent protective layer is transparent to the laser beam for recording an image on the image recording layer, and at the same time, the reflected light that can visually recognize the image formed on the image recording layer. It means that it is also transparent to the wavelength region. More specifically, the transmittance is preferably 80% or more for both laser light and reflected light, more preferably 90% or more, and still more preferably 95% or more. .
Note that “transparent” in each element constituting the transparent protective layer described later is also synonymous with “transparent” in the transparent protective layer.

As the 1st aspect of the transparent protective layer 60, it is comprised from the transparent adhesive layer or the transparent adhesion layer 62, and the transparent cover sheet 64 like the optical disk 100a shown by Fig.1 (a). .
As described above, in the present invention, when the transparent protective layer according to the first aspect is provided, an optical disk having another layer structure (for example, an optical disk for recording / reproducing using a blue-violet laser, for example, Blu- It is easy to divert the cover sheet of the same shape used in ray Disc), and it is possible to further reduce the manufacturing cost.

  As an adhesive used for the transparent adhesive layer constituting the transparent protective layer, for example, a UV curable resin, an EB curable resin, a thermosetting resin or the like is preferably used, and in particular, a UV curable resin is preferably used. In order to prevent warping of the optical disk, it is preferable that the UV curable resin constituting the adhesive layer has a small curing shrinkage rate. Examples of such UV curable resins include “SD-640” manufactured by Dainippon Ink and Chemicals, Inc.

  As the pressure-sensitive adhesive used for the transparent pressure-sensitive adhesive layer constituting the transparent protective layer, acrylic, rubber-based, and silicon-based pressure-sensitive adhesives can be used. From the viewpoint of transparency and durability, acrylic pressure-sensitive adhesive Is preferred. As such an acrylic pressure-sensitive adhesive, 2-ethylhexyl acrylate, n-butyl acrylate and the like are the main components, and in order to improve cohesion, short-chain alkyl acrylates and methacrylates such as methyl acrylate, ethyl acrylate, and methyl methacrylate are used. And acrylic acid, methacrylic acid, acrylamide derivatives, maleic acid, hydroxylethyl acrylate, glycidyl acrylate, and the like, which can be crosslinking points with the crosslinking agent, are preferably used. The glass transition temperature (Tg) and the crosslinking density can be changed by appropriately adjusting the mixing ratio and type of the main component, the short chain component, and the component for adding a crosslinking point.

  As a crosslinking agent used together with the said adhesive, an isocyanate type crosslinking agent is mentioned, for example. Such isocyanate-based crosslinking agents include tolylene diisocyanate, 4,4′-diphenylmethane diisocyanate, hexamethylene diisocyanate, xylylene diisocyanate, naphthylene-1,5-diisocyanate, o-toluidine isocyanate, isophorone diisocyanate, triphenylmethane triisocyanate, and the like. Isocyanates, products of these isocyanates with polyalcohols, and polyisocyanates formed by condensation of isocyanates can be used. Commercially available products of these isocyanates include Coronate L, Coronate HL, Coronate 2030, Coronate 2031, Millionate MR, Millionate HTL manufactured by Nippon Polyurethane; Takenate D-102 and Takenate D-110N manufactured by Takeda Pharmaceutical Co., Ltd. , Takenate D-200, Takenate D-202; Death Module L, Death Module IL, Death Module N, Death Module HL;

The transparent cover sheet constituting the transparent protective layer is not particularly limited as long as it is a transparent material sheet.
Specifically, it is preferable to use acrylic resins such as polycarbonate and polymethyl methacrylate; vinyl chloride resins such as polyvinyl chloride and vinyl chloride copolymers; epoxy resins; amorphous polyolefins; polyesters; Among these, it is more preferable to use polycarbonate or cellulose triacetate.

  The thickness of the transparent cover sheet is appropriately selected depending on the laser beam or NA for recording an image on the image recording layer, but in the present invention, it is preferably in the range of 10 to 600 μm, More preferably, it is in the range of 30 to 200 μm, and still more preferably in the range of 50 to 110 μm.

The transparent protective layer comprising the transparent adhesive layer or the transparent adhesive layer and the transparent cover sheet is formed as follows.
When a transparent adhesive layer is used, for example, a predetermined amount of an adhesive is applied onto a surface to be bonded made of a barrier layer, and the transparent cover sheet is placed thereon, or the adhesive is applied on the transparent cover sheet. After a predetermined amount is applied, the coated surface is aligned with the bonded surface comprising the barrier layer, and then the adhesive is spread evenly between the bonded surface and the cover sheet by spin coating. The transparent protective layer is formed by curing using a curing means (for example, irradiation of ultraviolet rays) corresponding to the adhesive.
Specifically, when the adhesive is an ultraviolet curable resin, it can be bonded by being cured by irradiation with ultraviolet rays.
Here, as the adhesive to be applied, the above-mentioned cured resin can be used as it is, or a coating solution prepared by dissolving the above-mentioned cured resin in an appropriate solvent such as methyl ethyl ketone or ethyl acetate can be used. .
In the case of using a transparent adhesive layer, for example, a predetermined amount of an adhesive is uniformly applied on a surface to be bonded composed of a barrier layer, and a cover sheet is placed thereon and then cured, Apply a predetermined amount of pressure-sensitive adhesive uniformly on one side of the cover sheet to form a pressure-sensitive adhesive coating film, and apply the pressure-sensitive adhesive film to the surface to be bonded by pressing it with a vacuum contact system or a rubber roller. A transparent protective layer is formed by combining and then curing.
In addition, you may use the adhesive film by which the adhesive layer was previously provided in the cover sheet.

As a 2nd aspect of a transparent protective layer, it is comprised from the transparent curable resin layer 66 like the optical disk 100b shown in FIG.1 (b).
As a material for the transparent curable resin layer, a UV curable resin, an EB curable resin, or a thermosetting resin suitable as an adhesive used in the transparent adhesive layer in the first aspect of the transparent protective layer can be used. In particular, it is preferable to use a UV curable resin. In order to prevent warping of the optical disk, it is preferable that the UV curable resin constituting the adhesive layer has a small curing shrinkage rate. Examples of such UV curable resins include UV curable resins such as “SD-640” manufactured by Dainippon Ink and Chemicals, Inc.

  In the present invention, the second laminate used when producing the optical disc having the layer configuration of (1) to (4) above has a barrier layer, an image recording layer, and an image recording layer on the transparent protective layer. It may be formed by sequentially providing a reflective layer (and, if necessary, a protective layer). The transparent protective layer used here is preferably a transparent resin film, and specifically, the transparent cover sheet can be applied.

The thickness of the transparent protective layer may be determined according to the layer structure of the optical disk, but is preferably in the range of 10 to 600 μm, preferably 30 to 200 μm from the viewpoint of the ability to protect the image recording layer and transparency. The range is more preferable, and the range of 50 to 110 μm is still more preferable.
Note that the thickness of the transparent protective layer is the sum of the thickness of the transparent adhesive layer or the transparent adhesive layer and the thickness of the transparent cover sheet in the first aspect. For example, the thickness of the transparent curable resin layer is obtained. Furthermore, if it is an aspect in the case of forming a 2nd laminated body, the thickness of a resin film will become the thickness of a transparent protective layer.
The light incident surface of the transparent protective layer in the present invention may be provided with a hard coat layer for preventing the light incident surface from being damaged during the production or use of the optical disc.

  As described above, the optical disc of the present invention may have an information recording layer that can be recorded / reproduced by laser light, or an information recording section (recording pits) in which information that can be reproduced by laser light is recorded. May be a read-only optical disc.

(Image recording method)
Image recording on the image recording layer of the optical disc of the present invention is performed using the optical disc of the present invention and a recording apparatus capable of recording image information on at least the image recording layer of the optical disc.
First, a recording apparatus used for recording on an optical disk according to the present invention will be described.

  In the optical disc of the present invention, recording of an image on the image recording layer and recording of optical information on the information recording layer can be performed by one optical disc drive (recording device) having a recording function on both layers. When one optical disk drive is used as described above, after recording on one of the image recording layer and the information recording layer, the recording can be reversed and recording can be performed on the other layer. Examples of the optical disc drive having a function of recording a visible image on the image recording layer are described in JP2003-203348A, JP2003-242750A, and the like.

A recording apparatus that records optical information on an information recording layer and records a visible image on an image recording layer includes at least a laser pickup that emits laser light and a rotating mechanism that rotates an optical disk. As the objective lens and laser used for the pickup, a conventionally known one can be used in accordance with an optical disk for recording an image.
A method of recording a visible image on the image recording layer using this recording apparatus will be described.
First, the laser pickup is focused on the image recording layer of the rotating optical disk by a rotating mechanism, and then tracking is performed on the formed tracking groove, and the relative movement is performed along the surface of the optical disk. In synchronism, laser light (for example, 780 nm) is modulated in accordance with image data such as characters and pictures to be imaged and irradiated toward the image recording layer to record a visible image. Such a configuration is described in, for example, Japanese Patent Application Laid-Open No. 2002-203321.
When recording a visible image on the image recording layer, tracking is not necessarily required. In this case, for example, laser irradiation corresponding to desired image data is performed by controlling a stepping motor or the like. A method of recording a visible image is used.

(Information recording method)
Next, recording of information (digital information) on the information recording layer using the recording apparatus will be described. When the information recording layer is a dye type, first, laser light is irradiated from a laser pickup while rotating the above-mentioned unrecorded optical disk at a predetermined recording linear velocity by a rotation mechanism. By this irradiation light, the dye of the information recording layer absorbs the light and the temperature rises locally, a desired pit is generated, and information is recorded by changing the optical characteristics of the region.
Note that the information recorded on the information recording layer is reproduced by irradiating the information recording layer of the rotated optical disc with laser light from a laser pickup.
Here, as the objective lens and laser used for the pickup, a conventionally known one can be used in accordance with the optical disk on which information is recorded.

On the other hand, the case where the information recording layer is a phase change type will be described. In the case of the phase change type, the information recording layer is made of the above-described material, and the phase change between the crystalline phase and the amorphous phase can be repeated by irradiation with laser light.
At the time of information recording, a concentrated laser light pulse is irradiated for a short time to partially melt the phase change information recording layer. The melted portion is rapidly cooled by heat diffusion and solidified to form an amorphous recording mark. At the time of erasing, the recording mark portion is irradiated with laser light, heated to a temperature lower than the melting point of the information recording layer, higher than the crystallization temperature, and cooled to crystallize the amorphous recording mark, Return to the original unrecorded state.

1 is a schematic cross-sectional view of an essential part showing a configuration example of an optical disc of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Board | substrate 20 ... Information recording layer 30 ... Reflective layer 40 ... Image recording layer 50 ... Barrier layer 60 ... Transparent protective layer 62 ... Transparent adhesive layer or transparent adhesion layer 64 ... Transparent cover sheet 66 ... Transparent curable resin layers 100a, 100b ... Optical disc

Claims (3)

  An optical disc comprising an information recording layer or information recording portion, a reflective layer, an image recording layer on which a visible image is recorded by laser light irradiation, a barrier layer, and a transparent protective layer in this order on a substrate .   2. The optical disc according to claim 1, wherein the transparent protective layer comprises a transparent adhesive layer or a transparent adhesive layer and a transparent cover sheet.   The optical disk according to claim 1, wherein the transparent protective layer is composed of a transparent curable resin layer.

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