JPH11149666A - Optical information record medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To lower reflectance and to suppress the occurrence of a data reproduction error by laminating a dye recording layer capable of recording information by irradiation with laser light, a reflecting layer and a protective layer on a transparent substrate and further forming a UV absorbing layer having higher UV absorption than the protective layer on the protective layer. SOLUTION: The UV absorbing layer on the protective layer has higher absorbance than the protective layer in the entire region of the wavelength range of 350-400 nm. The absorbance of the UV absorbing layer to light of 400 nm wavelength is >=0.9 and the average absorbance of the UV absorbing layer to light in the wavelength range or the absorbance in the entire region is higher than that of the protective layer by >=0.5. The UV absorbing layer is formed with a binder and a UV absorber. A UV-curing resin is used as the binder in consideration of productivity, etc. The UV absorber is dissolved or dispersed in the UV-curing resin or a soln. prepd. by dissolving the resin in a suitable solvent and the resultant coating liq. is applied on the protective layer to form the UV absorbing layer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a write-once optical information recording medium capable of recording and reproducing information by using a laser beam.

[0002]

2. Description of the Related Art Conventionally, an optical information recording medium (write-once type optical disk) on which information can be recorded only once by a laser beam is known as a write-once CD (so-called CD-R). CD-R type optical information recording media are commercially available CDs.
It has the advantage of being able to be played back using a player, and has recently become useful as a medium for storing information and data from personal computers and the like with the spread of personal computers and the like.

A CD-R type optical information recording medium (hereinafter referred to as CD)
A typical structure of -R) is a transparent disc-shaped substrate in which a recording layer made of an organic dye, a reflective layer made of a metal such as gold, and a protective layer made of a resin are laminated in this order. Writing (recording) of information on the optical information recording medium is performed by irradiating the information recording medium with a near infrared laser beam (usually a laser beam having a wavelength of around 780 nm) to irradiate the dye recording layer. Information is recorded by the portion absorbing the light and locally increasing the temperature, causing a physical or chemical change (for example, generation of a pit or the like) and changing its optical characteristics. On the other hand, reading (reproduction) of information is also usually performed by irradiating the information recording medium with laser light having the same wavelength as the recording laser light, and a portion where the optical characteristics of the dye recording layer has changed (such as generation of pits or the like) The information is reproduced by detecting a difference in reflectance between a portion recorded by the above-mentioned method and a portion that does not change (unrecorded portion).

A CD-R having a dye recording layer has a problem that the dye is generally deteriorated by light or heat, and the recording / reproducing characteristics are deteriorated. Especially for light such as sunlight or fluorescent light, C
Since the DR is exposed during handling such as use or transfer, or during storage, the dye is liable to photobleach, and its light resistance has been a problem. In order to suppress such photobleaching of the dye, generally, the dye recording layer includes:
Addition of an anti-fading agent called a singlet oxygen quencher such as a nitroso compound, a metal complex, a diimmonium salt, or an aminium salt is performed (for example,
JP-A-2-300288, JP-A-3-224793, JP-A-4-146189, etc.).

[0005] The reflection layer provided on the dye recording layer comprises:
Au (gold) is generally used because it provides a high reflectance of about 70% and is also excellent in corrosion resistance and the like.
It is formed using. However, since Au is expensive, in recent years, the reflective layer is made of a metal other than Au, for example, Ag.
(Silver), Cu (copper) or an alloy containing these as a main component is also used (see, for example,
Nos. 286432 and 4-49539). JP-A-3-286432 discloses Ag or Cu.
It is described that a higher reflectance can be obtained when Au is used than when Au is used.

[0006]

SUMMARY OF THE INVENTION The present inventor has proposed a CD-R
Focusing on the actual handling method of CD-
A study was made to suppress a decrease in R performance. According to the study, when a CD-R is used or stored, the CD-R is generally operated with its protective layer side up. Therefore, actually, more light is irradiated on the protective layer side than on the substrate surface side (the side on which recording and reproduction are performed). However, conventionally, since the light incident from the protective layer side is almost reflected by the reflective layer, little consideration has been given to the effect of the light incident from the protective layer side on the dye recording layer. According to a further study of the present inventors, a part of the light that enters from the protective layer side and is not reflected by the reflective layer is absorbed by the reflective layer or transmitted through the reflective layer to reach the dye recording layer. Was found to adversely affect the dye.
In particular, when the reflective layer is made of a metal (eg, Ag) that is relatively unstable (highly reactive) as compared with Au, for example,
It has been found that a decrease in reflectance and a data reproduction error are likely to occur.

An object of the present invention is to provide an optical information recording medium (optical disk) having improved light fastness. The present invention prevents a decrease in recording / reproducing characteristics due to light irradiated from the surface on the side where the protective layer is provided, and in particular, can additionally achieve high light resistance even when a reflective layer is formed of a metal other than Au. It is an object of the present invention to provide a type of optical information recording medium.

[0008] The present inventor has repeatedly studied the causes of the above-mentioned deterioration of the recording / reproducing characteristics. As a result, especially when the reflective layer is formed of a relatively reactive metal (eg, Ag) other than Au, its activity is further enhanced by light from the protective layer side, and the dye of the dye recording layer and its dye Reactions at the interface were likely to occur, and it was found that these reactions contributed to performance degradation. For example, as a dye compound, C
Cyanine dye having a benzoindolenine skeleton having lO ₄ ^- ion (for example, JP-A-4-175188)
In the case where is used, whether a chemical reaction occurs at the interface between the dye recording layer and the reflection layer, or Ag is altered, the recording characteristics of the dye are changed, and the performance is sometimes lowered.

[0009]

According to the research of the present inventors,
In a write-once optical information recording medium having a protective layer, by providing an ultraviolet absorbing layer having a higher ultraviolet absorbing function than the protective layer on the protective layer, the above reaction is suppressed,
Accordingly, it has been found that an optical information recording medium with reduced reflectivity and reduced occurrence of data reproduction errors can be manufactured.

The present invention relates to an optical information recording medium comprising a dye recording layer, a reflective layer and a protective layer on which information can be recorded by irradiating a laser beam on a transparent substrate in this order. An optical information recording medium characterized in that an ultraviolet absorbing layer having a higher ultraviolet absorbing property than the protective layer is provided on the layer. Here, the absorbance is log (I ₀ / I), where I ₀ is the intensity of light incident on the layer to be measured, and I is the intensity of light when the light passes through the layer.
Means the numerical value defined by It is also conceivable to add an ultraviolet absorber to the protective layer to enhance the ultraviolet absorbing function of the protective layer. However, when an ultraviolet absorber is added to the protective layer as disclosed in Japanese Patent Application Laid-Open No. 4-175188, the mechanical strength of the protective layer is reduced, for example, the protective layer is weak against external impact. This tends to cause undesirable effects such as scratches on the surface thereof, and deformation of the light reflecting layer when laser recording is performed.

The information recording medium of the present invention preferably has the following aspects. (1) The ultraviolet absorbing layer is a layer showing higher absorbance (average) than the protective layer in the wavelength range of 350 to 400 nm. More preferably, the layer exhibits higher absorbance than the protective layer in the entire region of 350 to 400 nm. (2) The absorbance of the ultraviolet absorbing layer for light having a wavelength of 400 nm is 0.5 or more (more preferably 0.9 or more). (3) The absorbance (average or entire region) of the ultraviolet absorbing layer with respect to light in the wavelength range of 350 to 400 nm is 0.3 or more (more preferably 0.5 or more, especially 0.7) than that of the protective layer.
Above) high. (4) The ultraviolet absorbing layer contains the ultraviolet absorbing agent in the range of 0.01 to 30% by weight (preferably 0.1 to 10% by weight, particularly 0.2 to 5% by weight). (5) the reflective layer is made of Ag metal, or Ag metal and Pt;
This is an alloy layer made of at least one metal selected from the group consisting of Cu, Au and Al. (6) The ultraviolet absorbing layer is 5 to 30 μm (more preferably,
8 to 20 μm).

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The optical information recording medium of the present invention comprises a dye recording layer, a reflective layer and a protective layer laminated on a transparent substrate in this order. Characterized in that an ultraviolet ray absorbing layer having a high refractive index is provided. Below, the substrate, dye recording layer, reflective layer,
A method for manufacturing the optical information recording medium of the present invention including a protective layer and an ultraviolet absorbing layer will be described in order.

The transparent substrate can be arbitrarily selected from various materials used as a substrate of a conventional optical information recording medium. Examples of the substrate material include glass; polycarbonate; acrylic resins such as polymethyl methacrylate; vinyl chloride resins such as polyvinyl chloride and vinyl chloride copolymer; epoxy resins; amorphous polyolefins and polyesters. These materials may be used together if desired. Note that these materials can be used in the form of a film or a rigid substrate. Among the above materials, polycarbonate is preferred from the viewpoints of moisture resistance, dimensional stability, cost, and the like.

An undercoat layer may be provided on the surface of the substrate on which the recording layer is provided, for the purpose of improving flatness, improving adhesion, and preventing deterioration of the recording layer. Examples of the material of the undercoat layer include polymethyl methacrylate, acrylic acid,
Methacrylic acid copolymer, styrene / maleic anhydride copolymer, polyvinyl alcohol, N-methylol acrylamide, styrene / vinyl toluene copolymer, chlorosulfonated polyethylene, nitrocellulose, polyvinyl chloride, chlorinated polyolefin, polyester, polyimide And high molecular substances such as vinyl acetate / vinyl chloride copolymer, ethylene / vinyl acetate copolymer, polyethylene, polypropylene and polycarbonate; and surface modifiers such as silane coupling agents.

The undercoat layer is prepared by dissolving or dispersing the above substances in an appropriate solvent to prepare a coating solution, and then applying this coating solution to the substrate surface by using a coating method such as spin coating, dip coating, or extrusion coating. Can be formed. The thickness of the undercoat layer is generally 0.005.
-20 μm, preferably 0.01-10 μm
m.

On the substrate (or undercoat layer), it is preferable to form a tracking groove or an unevenness (pre-groove) representing information such as an address signal. This pregroove is preferably formed directly on the substrate when injection molding or extrusion molding of a resin material such as polycarbonate.

The pre-groove may be formed by providing a pre-groove layer. As a material for the pregroove layer, a mixture of at least one monomer (or oligomer) of acrylic acid monoester, diester, triester and tetraester and a photopolymerization initiator can be used. The formation of the pre-groove layer is performed, for example, by first forming a precisely formed master (stamper).
A mixture of the above-mentioned acrylate and the polymerization initiator is applied thereon, and after further placing the substrate on the coating solution layer, the coating layer is cured by irradiating ultraviolet rays through the substrate or the matrix. To fix the substrate and the coating layer.
Next, it can be obtained by peeling the substrate from the matrix. The thickness of the pre-groove layer is generally 0.05 to 1
It is in the range of 00 μm, preferably in the range of 0.1 to 50 μm.

The depth of the pregroove is 0.01 to 0.3 μm
m is preferable, and the half width is
It is preferably in the range of 0.2 to 0.9 μm. By setting the depth of the pre-groove layer in the range of 0.15 to 0.2 μm, the sensitivity can be improved without substantially lowering the reflectance, which is particularly preferable. Therefore, such an optical disk (an optical disk in which a dye recording layer and a light reflecting layer are formed on a deep groove substrate) has a high sensitivity, so that it is possible to perform recording even with a low laser power, and thereby an inexpensive semiconductor laser is used. There is an advantage that the semiconductor laser can be used or the service life of the semiconductor laser can be extended.

A dye recording layer is provided on the substrate. The dye used in the dye recording layer is not particularly limited. For example,
Cyanine dye, phthalocyanine dye, imidazoquinoxaline dye, pyrylium / thiopyrylium dye, azulenium dye, squalilium dye, N
i, Cr and other metal complex dyes, naphthoquinone dyes,
Examples include anthraquinone dyes, indophenol dyes, merocyanine dyes, oxonol dyes, naphthoaniline dyes, triphenylmethane dyes, triallylmethane dyes, aminium / diimmonium dyes, and nitroso compounds. Among these dyes, cyanine dyes, phthalocyanine dyes, azulhenium dyes, squalilium dyes, oxonol dyes, and imidazoquinoxaline dyes are preferred. Particularly preferred are cyanine dyes. These cyanine dyes are described in, for example, the above-mentioned JP-A-4-175188.

The dye recording layer is formed by dissolving a dye, preferably an anti-fading agent (optionally with a binder) in a solvent to prepare a coating solution, and then applying the coating solution to the substrate surface. It can be performed by drying after forming a coating film. When the anti-fading agent is used in combination, the amount of the anti-fading agent is usually 0.1 to 50 to the amount of the cyanine dye.
% By weight, preferably from 0.5 to 45% by weight.
, More preferably in the range of 3 to 40% by weight, especially in the range of 5 to 25% by weight.

Examples of the solvent for the coating solution for the dye recording layer include:
Esters such as butyl acetate and cellosolve acetate; ketones such as methyl ethyl ketone, cyclohexanone and methyl isobutyl ketone; chlorinated hydrocarbons such as dichloromethane, 1,2-dichloroethane and chloroform; amides such as dimethylformamide; hydrocarbons such as cyclohexane; tetrahydrofuran; Ethers such as ethyl ether and dioxane; alcohols such as ethanol, n-propanol, isopropanol, n-butanol and diacetone alcohol; fluorinated solvents such as 2,2,3,3-tetrafluoropropanol; ethylene glycol monomethyl ether, ethylene Examples thereof include glycol ethers such as glycol monoethyl ether and propylene glycol monomethyl ether. The above-mentioned solvents can be used alone or in combination of two or more in consideration of the solubility of the dye used. Various additives such as an antioxidant, a UV absorber, a plasticizer, and a lubricant may be further added to the coating solution according to the purpose.

Typical examples of the anti-fading agent include nitroso compounds, metal complexes, diimmonium salts, aminium salts and the like. Examples of these are described in the above publications such as JP-A-2-300288, JP-A-3-224793, and JP-A-4-146189.

Examples of binders include, for example, gelatin,
Natural organic high molecular substances such as cellulose derivatives, dextran, rosin and rubber; and hydrocarbon resins such as polyethylene, polypropylene, polystyrene and polyisobutylene, polyvinyl chloride, polyvinylidene chloride, polyvinyl chloride / polyvinyl acetate copolymer Vinyl resin such as polymethyl acrylate, acrylic resin such as polymethyl methacrylate, polyvinyl alcohol, chlorinated polyethylene, epoxy resin, butyral resin, rubber derivative, initial condensate of thermosetting resin such as phenol / formaldehyde resin And other synthetic organic polymers. When a binder is used as a material for the dye recording layer, the upper limit of the amount of the binder used should be 20 parts by weight, preferably 10 parts by weight, more preferably 5 parts by weight, based on 100 parts by weight of the dye. It is.

The concentration of the dye in the coating solution for the dye recording layer thus prepared is generally in the range of 0.01 to 10% by weight, preferably in the range of 0.1 to 5% by weight.

Examples of the coating 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 dye recording layer may be a single layer or a multilayer. The thickness of the recording layer (after drying) is generally 20 to 500 nm.
And preferably in the range of 50 to 300 nm.

A reflective layer is provided on the dye recording layer, particularly for the purpose of improving the reflectance during information reproduction. The light-reflective substance, which is the material of the reflection layer, is a substance having a high reflectance with respect to a laser beam.
e, Y, Ti, Zr, Hf, V, Nb, Ta, Cr, M
o, W, Mn, Re, Fe, Co, Ni, Ru, Rh,
Pd, Ir, Pt, Cu, Ag, Au, Zn, Cd, A
1, Ga, In, Si, Ge, Te, Pb, Po, S
Metals such as n and Bi and semimetals or stainless steel can be mentioned. These substances may be used alone, or in combination of two or more kinds, or may be used as an alloy.

The structure of the present invention is particularly effective when the reflection layer is a layer made of Ag metal or Ag alloy.
Specifically, the reflection layer is made of Ag metal or Pt, Cu, Au.
Containing at least one metal selected from Al and Al
It is effective when formed from an alloy. In the case of the above Ag alloy, the content of metals other than Ag metal is at most 4%.
0% by weight, preferably 30% by weight or less;
More preferably, it is at most 20% by weight. In order to further improve properties such as storage stability, a small amount of other elements such as oxygen, fluorine, and sulfur or other compounds may be added to the reflective layer.

The reflection layer is formed, for example, by depositing a light-reflective substance,
It can be formed on the dye recording layer by sputtering or ion plating. The thickness of the reflective layer is generally in the range of 10 to 800 nm, preferably in the range of 20 to 500 nm, more preferably 50 to 500 nm.
３００300 nm.

A protective layer is provided on the reflective layer for the purpose of physically and chemically protecting the dye recording layer and the like. This protective layer can also be provided on the side of the substrate on which the dye recording layer is not provided for the purpose of improving the scratch resistance and moisture resistance. Examples of the material used for the protective layer include SiO, SiO ₂ ,
Examples include inorganic substances such as MgF ₂ , SnO ₂ , and Si ₃ N ₄ , and organic substances such as a thermoplastic resin, a thermosetting resin, and a UV-curable resin. The protective layer can be formed, for example, by laminating a film obtained by extrusion of a plastic on the reflective layer and / or the substrate via an adhesive. Alternatively, it may be provided by a method such as vacuum deposition, sputtering, or coating. Also,
In the case of a thermoplastic resin or a thermosetting resin, they can also be formed by dissolving these in an appropriate solvent to prepare a coating solution, applying the coating solution, and drying. In the case of a UV-curable resin, it is also possible to form the coating solution by using a coating solution as it is without using a solvent or by dissolving it in an appropriate solvent, applying the coating solution, and irradiating with UV light to cure. Can be. Various additives such as an antistatic agent and an antioxidant may be added to these coating solutions according to the purpose. The thickness of the protective layer is generally in the range from 0.1 to 100 μm.

An ultraviolet absorbing layer is provided on the protective layer. The ultraviolet absorbing layer is a layer having a higher ultraviolet absorbing property than the protective layer. This ultraviolet absorbing layer is preferably a layer exhibiting higher absorbance (average) than the protective layer in the wavelength range of 350 to 400 nm, more preferably 350 to 400 nm.
This is a layer showing higher absorbance than the protective layer in the entire region of 400 nm. The absorbance of the ultraviolet absorbing layer for light having a wavelength of 400 nm is preferably 0.5 or more (more preferably 0.9 or more). In addition, the ultraviolet absorbing layer is 35
It is preferable that the absorbance (average or entire region) with respect to light in the wavelength range of 0 to 400 nm is higher than the protective layer by 0.3 or more (more preferably 0.5 or more, particularly 0.7 or more). The ultraviolet absorbing layer can be formed from, for example, a binder and an ultraviolet absorbing agent.

Examples of usable ultraviolet absorbers include benzotriazole-based, benzophenone-based, oxalic anilide-based, and cyanoacrylate-based compounds. Among them, benzotriazole-based and benzophenone-based are preferred. In particular,
Benzotriazole-based ultraviolet absorbers include 2-
(2′-hydroxy-5-methylphenyl) benzotriazole, 2- (2′-hydroxy-3′-tert-butyl-5′-methylphenyl) -5-chlorobenzotriazole, 2- (2′-hydroxy- 4'-n-octyloxyphenyl) benzotriazole. Benzophenone-based UV absorbers include 2,
4-dihydroxybenzophenone (I), 2-hydroxy-4-methoxybenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone, 2-hydroxy-
4-methoxy-2'-carboxybenzophenone, 2
-Hydroxy-4-n-octyloxybenzophenone and 2-hydroxy-4-n-octadecyloxybenzophenone.

The binder for the ultraviolet absorbing layer is not particularly limited, but it is preferable to use an ultraviolet curable resin in consideration of productivity and the like. Note that the binder may be a compound that causes a crosslinking reaction by heat. UV curable resins are generally those in which a photopolymerization initiator is contained in a monomer or oligomer of a polymerizable compound having one or more reactive acryl groups in the molecule, or a mixture thereof, and a conventional UV-curable resin is used. It can be used by selecting from those known as curable resins. For example, as monofunctional monomers, tetrahydrofurfuryl acrylate, ethyl carbitol acrylate, dicyclopentyloxy acrylate, phenyl carbitol acrylate, nonylphenoxyethyl acrylate, hydroxyethyl acrylate, 2-hydroxy-3-phenoxypropyl acrylate, Acrylamide, acroylmorpholine, dimethylacrylamide, diethylacrylamide, N-vinylpyrrolidone can be mentioned. Examples of the polyfunctional acrylate include polyol polyacrylate, polyester acrylate, epoxy acrylate, urethane acrylate, pentaerythritol di (tri) acrylate, N, N'-methylenebisacrylamide, hexamethylenebisacrylamide and the like. Preferable examples include a monofunctional or polyfunctional monomer or oligomer having a polar group such as an acrylamide group, a vinylamino group, or a hydroxyl group.

Examples of the photopolymerization initiator include benzoin or its ethers such as benzoin, benzoin methyl ether, benzoin ethyl ether and benzoin isopropyl ether, benzophenone compounds such as benzophenone, and benzyl compounds such as benzyl, benzyl methyl ketal and benzyl ethyl ketal. Compound, 1-phenyl-
Examples thereof include hydroxyalkyl phenyl ketone compounds such as 2-hydroxy-2-methyl-2-propane.

The ultraviolet absorbing layer is, for example, as a binder
When using an ultraviolet-curable resin as described above, to the ultraviolet-curable resin as it is without using a solvent, or to an ultraviolet-curable resin dissolved in an appropriate solvent, the above-mentioned ultraviolet absorber is added and dissolved, A dispersion can be formed by preparing a dispersed coating liquid and applying it on the protective layer. As a coating method, a known method such as a spin coating method or a screen printing method can be used. It is preferable that the ultraviolet absorbing layer is formed uniformly on the entire surface of the protective layer so that good recording / reproducing characteristics by laser light irradiation can be obtained. The larger the amount of the UV absorber used, the higher the absorption performance can be. However, the mechanical strength of the layer to be formed is reduced. The content of the ultraviolet absorber in the ultraviolet absorbing layer is 0.01 to 30% by weight (more preferably, 0.1 to 10% by weight, particularly preferably,
(0.2 to 5% by weight). The ultraviolet absorbing layer has a thickness of 5 to 30 μm (more preferably,
The thickness is preferably 8 to 20 μm.

The optical information recording medium of the present invention is effective for a CD-R type optical disk, but can also be used for a DVD-R type optical disk.

The optical information recording method of the present invention is performed, for example, as follows using the optical information recording medium. As described below, the optical information recording medium of the present invention is capable of recording / reproducing at 1 × speed (1.2 to 1.4 m / sec) of a normal CD format, and has 4 × speed, 6 × speed, Alternatively, recording and reproduction at a higher speed can be performed. First, while rotating the optical information recording medium at a predetermined constant linear velocity (1.2 to 14 m / sec in the case of the CD format) or a predetermined constant angular velocity, recording light such as a semiconductor laser light is applied from the substrate side. Irradiate. By this light irradiation, the irradiated portion of the dye recording layer absorbs the light and locally raises the temperature, and pits are generated to change the optical characteristics, thereby recording information. As the recording light, a semiconductor laser beam having an oscillation wavelength in the range of 500 nm to 850 nm is used. The wavelength of the laser beam used is preferably 50
It is not less than 0 nm and not more than 800 nm. A wavelength in the range of 770 to 790 nm is suitable for a CD-R type optical information recording medium. For a DVD-R type optical information recording medium, a wavelength in the range of 620 to 680 nm is suitable.
The information recorded as described above can be reproduced by irradiating the semiconductor laser light from the substrate side while rotating the optical information recording medium at a predetermined constant linear speed, and detecting the reflected light.

[0037]

EXAMPLES Examples of the present invention and comparative examples will be described below. [Example 1] 2,2,3,3-Cyanine dye (A) and 10% by weight of anti-fading agent (B) based on the dye were used
It was dissolved in tetrafluoropropanol to prepare a coating solution for forming a dye recording layer. The preparation of the coating solution was performed for 1 hour using the ultrasonic dissolution method. The concentration of the resulting solution is
2.65% weight / volume.

[0038]

Embedded image

[0039]

Embedded image

This coating solution is applied on the surface of a spiral pre-groove (track pitch: 1.6 μm, pre-groove width: 0.5 μm, pre-groove depth: 0.17 μm).
Is applied by spin coating to a surface on the pre-groove side of a polycarbonate substrate (diameter: 120 mm, thickness: 1.2 mm, manufactured by Teijin Limited, trade name: Panlite AD5503), which is dried. The dye recording layer (thickness (in the groove): about 150 nm)
Was formed.

Next, Ag metal was sputtered on the dye recording layer (DC magnetron sputtering apparatus: sputtering power:
1.5 kW, sputtering gas pressure: 2 Pa, sputtering gas:
Ar, the flow rate of Ar was 50 sccm), and the film thickness was about 90.
The light reflection layer of nm was formed. Further, a UV curable resin (trade name: SD-1700, manufactured by Dainippon Ink and Chemicals, Inc.) is applied on the light reflecting layer by spin coating, and then cured by irradiating ultraviolet rays from above, and the layer thickness is adjusted. A 10 μm protective layer was formed.

On the protective layer thus obtained, a UV curable resin containing a UV absorber (UVscreen) was used.
395, manufactured by INC-TEC).
(00 mesh) on the entire surface of the protective layer.
Then, an ultraviolet ray was irradiated from above on this with a high-pressure mercury lamp to cure the resin, thereby forming an ultraviolet absorbing layer having a layer thickness of 12 μm. By the above steps, the substrate, the dye recording layer, the light reflection layer,
A CD-R type optical disk according to the present invention, in which a protective layer and an ultraviolet absorbing layer were laminated in this order, was manufactured.

Example 2 In Example 1, the following cyanine dye (C) was used instead of the cyanine dye (A), and the following anti-fading agent (D) was used instead of the anti-fading agent (B). A coating solution for forming a dye recording layer was prepared in the same manner except that the coating solution was used.

[0044]

Embedded image

[0045]

Embedded image

This coating solution is applied onto the surface of a spiral pre-groove (track pitch: 1.6 μm, pre-groove width: 0.4 μm, pre-groove depth: 0.16 μm).
Is a polycarbonate transparent substrate (diameter: 120 mm, thickness: 1.2 mm, manufactured by Teijin Ltd., trade name: Panlite AD5503) formed by injection molding and having a rotation speed of 300 rpm. ~ 200
The recording layer (thickness (within the pre-groove): about 150 nm) was formed by applying the solution by spin coating while changing the speed to 0 rpm, and then drying.

Next, an Ag metal was sputtered on the recording layer to form a reflective layer having a thickness of about 150 nm. Further, a UV curable resin (trade name: SD-2003, manufactured by Dainippon Ink and Chemicals, Inc.) is applied on the reflective layer by spin coating while changing the rotation speed from 100 rpm to 2000 rpm, and then applied to a high-pressure mercury lamp. UV light was applied to cure the resin, thereby forming a protective layer having a thickness of 8 μm.

On the protective layer thus obtained, a UV curable resin containing a UV absorber (UVscreen) was used.
395, manufactured by INC-TEC).
(00 mesh) on the entire surface of the protective layer.
Then, an ultraviolet ray was irradiated from above on this with a high-pressure mercury lamp to cure the resin, thereby forming an ultraviolet absorbing layer having a layer thickness of 12 μm. Through the above steps, a CD-R type optical disc according to the present invention, in which a transparent substrate, a dye recording layer, a reflective layer, a protective layer, and an ultraviolet absorbing layer were laminated in this order, was manufactured.

Comparative Example 1 A comparative CD-R was prepared in the same manner as in Example 1 except that no ultraviolet absorbing layer was provided.
Type optical discs were manufactured.

Comparative Example 2 A comparative CD-R type optical disk was manufactured in the same manner as in Example 1, except that the ultraviolet absorbing layer was provided only in a half area of the protective layer surface.

[Evaluation of UV Absorption Performance] Examples 1 and 2
UV curable resin containing UV absorber (U)
Vscreen 395 (manufactured by INC-TEC) (UV absorbing layer), and a UV-curable resin (trade name:
FIG. 1 attached shows the ultraviolet absorption performance of a layer (protective layer) formed only of SD-2003 (manufactured by Dainippon Ink and Chemicals, Incorporated; used in Example 2) as an absorption spectrum. The absorption spectrum A in FIG. 1 shows the absorption spectrum of a sample in which a 10 μm thick ultraviolet absorbing layer is provided on a transparent polycarbonate substrate (thickness: 1.2 mm). The absorption spectrum B in FIG. 1 shows an absorption spectrum of a sample in which a protective layer (a layer formed only of an ultraviolet curable resin) is provided with a thickness of 10 μm on the same transparent polycarbonate substrate as described above. From the absorption spectrum shown in FIG. 1, the ultraviolet absorbing layer according to the present invention has 3
It can be seen that the absorbance at a wavelength of 50 to 400 nm is considerably higher than that of the protective layer.

[Evaluation as Optical Information Recording Medium]
And optical disks obtained in Comparative Examples 1 and 2, were subjected to a light resistance (preservation) test by the following method.

(Light Resistance Test) The optical disk was housed in a separately prepared transparent sample holder, and irradiated with light from above using a Xe lamp for 100 hours. At this time, the integrated light quantity irradiated was 110000 kJ / m ² .

The light resistance test includes (1) irradiating an optical disk on which data has been recorded in advance with light under the above conditions, and then reproducing the data; and (2) irradiating light on the optical disk without recording data on the above conditions. And then record the data,
Reproduction was performed in two ways. Recording and reproduction were performed at 1 × speed in each case.

(1) In the case where data is recorded in advance and light is irradiated under the above conditions and then reproduced, data is recorded on an optical disk (before storage) that is not irradiated with light, and an OTM-2000 evaluation machine (manufactured by Pulstec) is used. And the block error rate and 3T pit jitter at the optimum power were measured. The data recorded on the optical disk before the light irradiation was irradiated with the light under the above conditions (after storage), and then the data was stored in the OTM-200.
Reproduction was performed using a 0 evaluator (manufactured by Pulstec), and the block error rate and 3T pit jitter at the optimum power were measured. Then, the data before and after the storage were compared to evaluate the recording / reproducing characteristics. Table 1 shows the evaluation results.

[0056]

[Table 1] Table 1 ──────────────────────────────────── Block error rate (pcs / sec) 3T pit jitter (ns) Before storage After storage Before storage After storage ──────────────────────────────────── Example 1 3.4 → 4.4 23.0 → 26.4 Example 2 3.4 → 4.5 23.8 → 26.5 Comparative Example 1 3.5 → 15.8 22.8 → 32. 5 Comparative Example 2 3.4 → 17.6 24.0 → 38.5 ──────────────────────────────── ────

From the results shown in Table 1 above, the optical disk according to the present invention provided with the ultraviolet absorbing layer (Examples 1 and 2)
In the case of (1), a comparative optical disk without the ultraviolet absorbing layer (Comparative Example 1) or a comparative optical disk with the ultraviolet absorbing layer provided only in half the surface of the protective layer (Comparative Example 2) ), The increase in the block error rate and the 3T pit jitter is small, so that the degree of photobleaching of the dye is small even in the light fastness test. Therefore, the optical disc according to the present invention has high light fastness. I understand. In the case of Comparative Example 2, since there is a region where the ultraviolet absorbing layer is formed and a region where it is not formed,
In particular, the characteristics of 3T pit jitter are further reduced. That is, the size of the pits formed differs between the region having the ultraviolet absorbing layer and the region not having the ultraviolet absorbing layer (region having only the protective layer) because the degree of deterioration of the dye recording layer due to the irradiation of the ultraviolet light is different. Therefore, if pits having different sizes are formed in one sample, the pits are measured as signal variations, and the value of jitter increases.

(2) When light is irradiated under the above conditions, and data is recorded and then reproduced. Data is recorded on an optical disk (before storage) that is not irradiated with light, and an OTM-2000 evaluation machine (Pulstec Co., Ltd.) ) And the block error rate and 3T pit jitter at the optimum power were measured. After light irradiation (after storage) under the above conditions, the data recorded on the optical disk is reproduced using an OTM-2000 evaluator (manufactured by Pulstec), and the block error rate and 3T pit jitter at the optimum power are measured. did.
Then, the data before and after the storage were compared to evaluate the recording / reproducing characteristics. Table 2 shows the evaluation results.

[0059]

[Table 2] Table 2 ──────────────────────────────────── Block error rate (pcs / sec) 3T pit jitter (ns) Before storage After storage Before storage After storage ──────────────────────────────────── Example 1 3.3 → 4.5 23.6 → 25.2 Example 2 3.7 → 4.7 24.2 → 25.5 Comparative Example 1 3.5 → 10.7 24.3 → 28. 4 Comparative Example 2 3.3 → 9.7 25.1 → 32.2 ──────────────────────────────── ────

From the results shown in Table 2 above, in the case of the optical disc according to the present invention provided with the ultraviolet absorbing layer (Examples 1 and 2), the increase in the block error rate and the 3T pit jitter was small, and thus the light resistance was high. It can be seen that the recording / reproducing characteristics after the performance test were also excellent.

[0061]

According to the optical information recording medium of the present invention, since the ultraviolet absorbing layer is provided on the protective layer, deterioration of the dye recording layer due to light incident from the protective layer side is prevented, and high light resistance is obtained. Is shown. In particular, a metal other than Au (for example,
It is possible to suppress a decrease in recording / reproducing characteristics such as a decrease in reflectivity and occurrence of a data reproduction error, which are problems when formed of Ag metal or Ag alloy). Therefore, a metal such as Ag, which is advantageous in terms of cost, can be used as the material of the reflective layer, so that a less expensive, light-resistant CD-R type or DVD-R type optical information recording medium can be used. Can be provided.

[Brief description of the drawings]

FIG. 1 shows absorption spectra of an ultraviolet absorbing layer and a protective layer.

Claims (4)

[Claims] 1. An optical information recording medium comprising a transparent substrate, a dye recording layer capable of recording information by irradiating a laser beam, a reflective layer, and a protective layer laminated in this order. An optical information recording medium, further comprising an ultraviolet absorbing layer having a higher ultraviolet absorbing property than the protective layer. 2. The optical information recording medium according to claim 1, wherein the ultraviolet absorbing layer contains an ultraviolet absorbing agent. 3. The reflection layer according to claim 1, wherein the reflection layer is a layer of Ag metal or an alloy of Ag metal and at least one metal selected from the group consisting of Pt, Cu, Au and Al. An optical information recording medium according to claim 1. 4. The optical information recording medium according to claim 1, wherein the ultraviolet absorbing layer has a thickness of 5 to 30 μm.