JP2001344811A - Optical information recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical information recording medium excellent in recording sensitivity and recording characteristic (jitter). SOLUTION: A dyestuff recording layer, the thickness of which is 50-160 nm and on which information can be recorded by incorporating an organic dyestuff selected to have 0.045-0.075 fading coefficient k when irradiated with the laser beam having recording laser wavelength, is formed on a transparent substrate where a pre-groove of 150-200 nm depth is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art Conventionally, a write-once optical information recording medium (optical disk) on which information can be recorded only once by a laser beam has been developed.
It is called CD-R and is widely known. A typical structure of this CD-R type optical information recording medium is that an organic dye is formed on a transparent disc-shaped substrate on which a guide groove (pre-groove) for tracking a laser beam irradiated during recording is formed. Of a dye recording layer, a light reflection layer made of a metal such as gold, and a protective layer made of a resin. Recording of information on the optical disk is performed by irradiating the optical disk with near-infrared laser light (usually laser light having a wavelength of around 780 nm), and the irradiated portion of the dye recording layer absorbs the light. The temperature locally rises, and the optical characteristics of the portion change due to a physical or chemical change (for example, generation of a pit or the like), and information is recorded. On the other hand, in reproducing information, a laser beam having the same wavelength as the recording laser beam is irradiated onto the optical disc, and a portion where the optical characteristics of the dye recording layer has changed (recorded portion) and a portion where the optical characteristics have not changed (not yet recorded). This is performed by detecting a difference in reflectance with the recording portion).

[0003]

However, the CD-
R is a medium premised on a system for recording information on the user side using a simple recording device. Therefore, ROM
The pit formation accuracy is lower than in the case of a mold medium. As a result, there is a problem that variation in the pit length called jitter increases and, for example, a reproduction failure occurs when the reproduction accuracy of the reproduction apparatus is lowered.

On the other hand, the present inventors have studied various methods for improving the jitter and found that the jitter can be improved by reducing the thickness of the dye recording layer. Simply reducing the recording density causes a decrease in recording sensitivity.
There is a problem.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an optical information recording medium having good recording sensitivity and recording characteristics (jitter).

[0006]

In order to achieve the above object, an optical information recording medium of the present invention has a groove depth of 150 to 20.
An organic dye selected to have a thickness of 50 to 160 nm and an extinction coefficient k at a recording laser wavelength of 0.045 to 0.075 is placed on a transparent substrate having a 0 nm pregroove formed thereon. A dye recording layer on which information can be recorded by containing the dye recording layer is formed.

In the optical information recording medium of the present invention, even if the thickness of the dye recording layer is reduced to 50 to 160 nm, the organic dye contained in the dye recording layer has an extinction coefficient k at the recording laser wavelength of 0. .045 to 0.075 so that the groove depth of the pre-groove is 150 to 2
In the range of 00 nm, good recording sensitivity and good jitter can be obtained. be able to.

In the above optical information recording medium, the groove depth of the pre-groove is more preferably from 160 to 190 nm, and most preferably from 165 to 185 nm. Also,
The groove width of the pre-groove is preferably 400 to 630 nm, more preferably 410 to 590 nm. The extinction coefficient k of the dye recording layer at the recording laser wavelength is 0.05 to 0.07.
Is preferable. The thickness of the dye recording layer is more preferably in the range of 70 to 150 nm, most preferably 90 to 150 nm.
１４０140 nm.

The optical information recording medium of the present invention forms a coating film by applying a coating solution having a dye concentration of 0.5 to 1.5 g / 100 ml on the surface of the transparent substrate on which the pregroove is formed. Then, by drying the formed coating film, a dye recording layer can be formed and manufactured.

In the above production method, the coating solvent is preferably a fluorinated solvent such as 2,2,3,3-tetrafluoropropanol. The coating method is preferably a spin coating method. When the dye recording layer is formed by the spin coating method, the supply amount of the coating liquid is 0.1 to 1.
0 ml is preferable, and the number of rotations when supplying the coating liquid is 100 to 5
00 rpm is preferred. After supplying the coating liquid, drying is performed by gradually increasing the number of revolutions, but the number of revolutions during drying is 1500 to 8
000 rpm is preferable, and the acceleration for increasing the rotation speed is 1
The range of 0 to 3000 rpm / s ² is preferable. If the time from the start of coating to the end of drying is too short, a uniform film thickness distribution cannot be obtained, and if it is too long, the productivity is reduced.

In the optical information recording medium of the present invention, it is preferable to provide a light reflection layer on the dye recording layer, and it is preferable to provide a protective layer on the surface opposite to the substrate.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the optical information recording medium of the present invention will be described below in detail.

As shown in FIG. 1, a CD-R type optical information recording medium according to an embodiment of the present invention has a dye recording layer 12 on a disc-shaped transparent substrate 10 on which a pre-groove is formed.
The light reflecting layer 14 and the protective layer 16 may be provided in this order. Further, an intermediate layer or the like may be provided as necessary as described later.

In the present invention, (1) the pregroove formed on the transparent substrate has a groove depth of 150 to 200 nm,
(2) The dye recording layer has a thickness of 50 to 160 nm, and (3) the extinction coefficient k at the recording laser wavelength of the dye recording layer is 0.045 to 0.075. By satisfying the three requirements (1) to (3), it is possible to achieve both good recording sensitivity and good recording characteristics (jitter).

Hereinafter, the structure of each layer will be described in detail.

On the transparent substrate 10, tracking grooves or grooves (pre-grooves) representing information such as address signals are formed at a predetermined track pitch. FIG. 2 is a schematic sectional view showing the shape of the pregroove. D is the groove depth, which is the distance from the substrate surface before the groove is formed to the deepest point of the groove. W is the groove width, which is the width of the groove at a depth of D / 2.

In the present invention, the groove depth of the pregroove represented by "D" in FIG. 2 needs to be in the range of 150 to 200 nm. If the groove depth is smaller than 150 nm, the jitter increases and the recording characteristics deteriorate, and if the groove is too shallow, tracking failure occurs. on the other hand,
If the groove depth is larger than 200 nm, the reflectivity for recording light and reproduction light decreases, and the recording / reproduction characteristics deteriorate.

Since the larger the groove depth, the more difficult it is to manufacture the groove, considering the balance between the degree of jitter improvement and the ease of manufacture, when the upper limit of the groove depth is 200 nm, the lower limit of the groove depth is 160 nm is more preferred, and 165
nm is more preferred. When the lower limit of the groove depth is 150 nm, the upper limit of the groove depth is more preferably 190 nm, and 1
85 nm is more preferred. Also, the upper limit of the groove depth is 19
When it is set to 0 nm, the lower limit of the groove depth is more preferably 160 nm, further preferably 165 nm. When the lower limit of the groove depth is 160 nm, the upper limit of the groove depth is more preferably 190 nm, and further preferably 185 nm. Further, when the upper limit of the groove depth is 185 nm, the lower limit of the groove depth is 1
60 nm is more preferred, and 165 nm is even more preferred. When the lower limit of the groove depth is 165 nm, the upper limit of the groove depth is more preferably 190 nm, and further preferably 185 nm.

The groove width of the pregroove represented by "W" in FIG. 2 is preferably in the range of 400 to 630 nm. If the groove width is smaller than 400 nm or larger than 630 nm, the jitter tends to decrease. In order to suppress the occurrence of tracking errors, the upper limit of the groove width is set to 630 nm.
When, the lower limit of the groove width is more preferably 420 nm,
450 nm is more preferred. In order to suppress the occurrence of crosstalk, when the lower limit of the groove width is 400 nm, the upper limit of the groove width is more preferably 600 nm, and 580 n
m is more preferred.

The track pitch of the pregroove is
The range is preferably 0.1 to 50 μm, more preferably 0.2 to 30 μm, and still more preferably 0.3 to 10 μm.
It is.

The transparent substrate 10 is a disk-shaped transparent resin substrate having a diameter of 120 ± 3 mm and a thickness of 0.6 ± 0.1.
mm or a diameter of 80 ± 3 mm and a thickness of 0.6
A disc-shaped substrate of ± 0.1 mm is generally used. In addition,
Here, “transparent” means transparent to recording light and reproduction light.

Examples of the material of the transparent substrate 10 include glass; polycarbonate; acrylic resins such as polymethyl methacrylate; vinyl chloride resins such as polyvinyl chloride and vinyl chloride copolymer; epoxy resins; amorphous polyolefin and polyester. Can be mentioned. If desired, they may be used in combination. Among the above materials, polycarbonate is preferred from the viewpoints of moisture resistance, dimensional stability, cost, and the like.

The above-described pregroove having a predetermined shape can be formed directly on the transparent substrate 10 when a resin material such as polycarbonate is injection-molded or extruded. Alternatively, 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. For the formation of the pre-groove layer, for example, first, a mixed solution composed of the above-mentioned acrylate ester and the polymerization initiator was applied on a precisely formed master (stamper), and further, a substrate was placed on this coating solution layer. Thereafter, the coating layer is cured by irradiating ultraviolet rays through the substrate or the matrix to fix the substrate and the coating layer. Next, the pregroove can be obtained by peeling the substrate from the matrix. The thickness of the pre-groove layer is generally 0.05 to
In the range of 100 μm, preferably 0.1 to 50 μm
Range.

On the surface of the transparent substrate 10 on the side where the dye recording layer 12 is provided, an undercoat layer can be provided for the purpose of improving flatness, improving adhesive strength, preventing deterioration of the dye recording layer, and the like. Examples of the material of the undercoat layer include polymethyl methacrylate, acrylic acid / methacrylic acid copolymer, styrene / maleic anhydride copolymer, polyvinyl alcohol, N-methylolacrylamide, styrene.
Vinyl toluene copolymer, chlorosulfonated polyethylene, nitrocellulose, polyvinyl chloride, chlorinated polyolefin, polyester, polyimide, vinyl acetate / vinyl chloride copolymer, ethylene / vinyl acetate copolymer, polyethylene, polypropylene, polycarbonate, etc. Polymer substances; and surface modifiers such as silane coupling agents. The undercoat layer is prepared by dissolving or dispersing the above substance in an appropriate solvent to prepare a coating solution, and then applying the coating solution to the substrate surface using a coating method such as spin coating, dip coating, or extrusion coating. Can be formed. 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.

On the surface of the transparent substrate 10 (or undercoat layer) on which the pregroove is formed, a dye recording layer 12 capable of recording information by containing an organic dye is provided. The dye recording layer 12 may be a single layer or a multilayer.

In the present invention, the extinction coefficient k of the dye recording layer 12 at the recording laser wavelength is 0.045 to 0.07.
The organic dye to be contained is selected so as to be in the range of 5. If the extinction coefficient k is smaller than 0.045, the recording sensitivity is reduced, and if the extinction coefficient k is larger than 0075, the reflectivity to recording light and reproduction light is reduced.

Since the recording sensitivity and the reflectivity compete as described above, when the upper limit of the extinction coefficient k is 0.075, the lower limit of the extinction coefficient k is more preferably 0.05. When the lower limit of the extinction coefficient k is 0.045, the upper limit of the extinction coefficient k is 0.045.
07 is more preferred. Also, the upper limit of the extinction coefficient k is set to 0.0
When it is set to 7, the lower limit of the extinction coefficient k is more preferably 0.05.

The extinction coefficient k of the dye recording layer is the absolute value of the imaginary part of the complex refractive index of the dye recording layer with respect to the recording laser wavelength, and is a value that serves as an index of light absorption. Means a value determined from the measured values of the transmittance and reflectance of the dye recording layer with respect to the recording laser wavelength in accordance with the following method.

The extinction coefficient k is generally represented by the following equation (1) using the absorption coefficient α.

K = αλ / 4π (1) (where λ is the recording laser wavelength) On the other hand, the optical density α _d which is the product of the absorption coefficient α of the dye recording layer and the film thickness _d is: Actually measured transmittance T ₀ and reflectance R ₀ for incident light from the dye recording layer side, reflectance R ₀ ′ for incident light from the side opposite to the dye recording layer side, and reflectance Rs only on the substrate. And can be determined by the following equation (2).

Α _d = ln (1 / T ₀ ) + ln (1-R ₀ ) + ln (1-R ₀ ′ + 1 / 2R _s ) Equation (2) Therefore, the disappearance of the dye recording layer with respect to the recording laser wavelength The decay coefficient k can be obtained by the following equation (3) in which equation (2) is substituted into equation (1).

K = λ [ln (1 / T ₀ ) + ln (1-R ₀ ) + ln (1-R ₀ ′ + 1 / 2Rs)] / 4πd (3) The reflectance only on the substrate R _s is the reflectance at the portion of the recording medium where no dye recording layer is provided.

The organic dye is appropriately selected from cyanine dyes, azo dyes, phthalocyanine dyes, oxonol dyes, and pyromethene dyes so that the extinction coefficient k of the dye recording layer has a desired value. These dyes may be used in an appropriate combination so that the extinction coefficient k of the dye recording layer has a desired value.

In the present invention, it is necessary that the thickness of the dye recording layer is in the range of 50 to 160 nm.
FIG. 3 shows the dye recording layer 1 provided on the surface of the transparent substrate 10.
It is a schematic sectional drawing showing the 2nd shape. In the present invention, “the thickness of the dye recording layer” means the thickness of the dye recording layer at the portion where the groove is formed, and as shown by “A” in FIG. From the surface of the dye recording layer to the deepest point of the groove.

Conventionally, the dye recording layer has a thickness of 200 n on the groove.
In general, the dye recording layer is formed to have a thickness of 50 to 160 nm, which is a conventional CD.
The feature is that it is thinner than -R. If the thickness of the dye recording layer is less than 50 nm, the sensitivity is reduced and recording becomes impossible,
If the thickness of the dye recording layer is larger than 160 nm, the jitter increases and the recording / reproducing characteristics deteriorate.

Since the recording sensitivity and the jitter compete with each other as described above, when the upper limit of the thickness of the dye recording layer is set to 160 nm, the lower limit of the thickness of the dye recording layer is more preferably 70 nm, further preferably 90 nm. When the lower limit of the thickness of the dye recording layer is 50 nm, the upper limit of the thickness of the dye recording layer is 1
50 nm is more preferred, and 140 nm is even more preferred. When the upper limit of the thickness of the dye recording layer is 150 nm, the lower limit of the thickness of the dye recording layer is more preferably 70 nm, further preferably 90 nm. When the lower limit of the thickness of the dye recording layer is 70 nm, the upper limit of the thickness of the dye recording layer is 1
50 nm is more preferred, and 140 nm is even more preferred. Further, when the upper limit of the thickness of the dye recording layer is 140 nm, the lower limit of the thickness of the dye recording layer is more preferably 70 nm, and further preferably 90 nm. When the lower limit of the thickness of the dye recording layer is 90 nm, the upper limit of the thickness of the dye recording layer is more preferably 150 nm, and still more preferably 140 nm.

The dye recording layer 12 is prepared by dissolving a discoloration inhibitor and a binder, if necessary, in a solvent in addition to the organic dye described above to prepare a coating solution. It can be formed by applying a film on the surface of the formed film to form a coating film, and drying the formed coating film. The dye concentration in the coating solution is preferably in the range of 0.5 to 1.5 g / 100 ml, and more preferably in the range of 0.6 to 1.1 g / 100 ml in order to form a thin film. By using a coating solution having a high dye concentration, a thinner dye recording layer can be obtained.

Examples of the coating method include a spray method, a spin coating method, a dipping method, a roll coating method, a blade coating method, a doctor roll method, and a screen printing method. When the dye recording layer is formed by the spin coating method, a thin film of the dye recording layer can be formed using a conventionally known spin coating apparatus. The supply amount of the coating liquid is preferably 0.1 to 1 ml per sheet, and 0.2 to 0.1 ml.
5 ml is more preferred. The number of rotations when supplying the coating liquid is 100
The rotation speed is preferably from 500 to 500 rpm, more preferably from 200 to 400 rpm. After supplying the coating liquid, drying is performed by gradually increasing the number of revolutions, but the number of revolutions during drying is 1500 to 8000 rpm.
m is preferable, 2000 to 6000 rpm is more preferable, and 3000 to 5000 rpm is particularly preferable. Acceleration increasing the rotation speed is preferably in the range of 10~3000rpm / s ^2, the range of 50~1000rpm / s ² is more preferable. The time required from the start of application to the end of drying is
If the length is too short, a uniform film thickness distribution cannot be obtained, and if the length is too long, the productivity decreases. Therefore, the range is preferably 3 to 15 seconds, more preferably 5 to 10 seconds. By performing spin coating under the above conditions, a thin film having a thickness of 150 nm or less can be formed.

As the coating solvent, 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; ethers such as tetrahydrofuran, ethyl ether and dioxane; alcohols such as ethanol, n-propanol, isopropanol, n-butanol and diacetone alcohol; and 2,2,3,3-tetrafluoropropanol Fluorinated solvents; glycol ethers such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, and propylene glycol monomethyl ether; DOO but can, in order to form a thin film, particularly preferred is a fluorine-based solvent such as 2,2,3,3 tetrafluoropropanol. The above solvents can be used alone or in combination of two or more in consideration of the solubility of the compound 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 according to the purpose.

Representative examples of the anti-fading agent include nitroso compounds, metal complexes, diimmonium salts and aminium salts. These examples are described in, for example, JP-A-2-300288, JP-A-3-224793, and JP-A-4-224793.
No. 146189.

In the present invention, a discoloration inhibitor represented by the following general formula (1) is preferred.

[0042]

Embedded image

R ₁₁ and R _{12 in the} above formula (1) each independently represent a hydrogen atom or a monovalent substituent. The substituent represented by R ₁₁ and R ₁₂ is a halogen atom or a substituent obtained by combining a carbon atom, an oxygen atom, a nitrogen atom or a sulfur atom, and specifically, an alkyl group, an alkenyl group, an aralkyl Group, aryl group, heterocyclic group, halogen atom, cyano group, nitro group, mercapto group, hydroxy group, alkoxy group, aryloxy group, alkylthio group, arylthio group, acyloxy group, amino group, alkylamino group, amide group, Sulfonamide group, sulfamoylamino group, alkoxycarbonylamino group, alkoxysulfonylamino group, ureido group, thioureido group, acyl group, alkoxycarbonyl group, carbamoyl group, alkylsulfonyl group, alkylsulfinyl group,
Examples include a sulfamoyl group, a carboxyl group (including a salt), and a sulfo group (including a salt). These may be further substituted with these substituents.

R ₁₁ and R ₁₂ each independently represent a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, a halogen atom, a cyano group, an alkoxy group having 1 to 6 carbon atoms, an alkylthio group having 1 to 6 carbon atoms, An amide group having 1 to 6 carbon atoms, a sulfonamide group having 1 to 6 carbon atoms, an ureido group having 1 to 6 carbon atoms, an acyl group having 1 to 6 carbon atoms, an alkoxycarbonyl group having 2 to 6 carbon atoms, A carbamoyl group having 6 carbon atoms, an alkylsulfonyl group having 1 to 6 carbon atoms, and an alkylsulfinyl group having 1 to 6 carbon atoms are preferable, an alkoxy group having 4 or less carbon atoms is more preferable, and a methoxy group and an ethoxy group are particularly preferable.

When an anti-fading agent is used, its amount is usually in the range of 0.1 to 50% by mass, preferably 0.5 to 45% by mass, based on the amount of the dye. More preferably, it is in the range of 3 to 40% by mass, particularly 5 to 25% by mass.

Examples of the binder include natural organic high-molecular substances such as gelatin, cellulose derivatives, dextran, rosin and rubber; and hydrocarbon resins such as polyurethane, polyethylene, polypropylene, polystyrene and polyisobutylene; polyvinyl chloride Vinyl resins such as polyvinyl chloride, polyvinylidene chloride, polyvinyl chloride / polyvinyl acetate copolymer; acrylic resins such as polymethyl acrylate and polymethyl methacrylate; polyvinyl alcohol, chlorinated polyethylene, epoxy resin, butyral resin, rubber derivatives And synthetic organic polymers such as precondensates of thermosetting resins such as phenol-formaldehyde resins. When a binder is used in combination as a material for the dye recording layer, the amount of the binder used is 0.2 to 20 parts by weight, preferably 0.5 to 10 parts by weight, based on 100 parts by weight of the dye.
More preferably, it is 1 to 5 parts by weight.

Further, an intermediate layer may be provided between the dye recording layer 12 and the light reflection layer 14 for improving the reflectance and the sensitivity. The material used for the intermediate layer is Si
Examples thereof include inorganic substances such as O ₂ , SiN, MgF ₂ , and TiO ₂ , and organic substances such as butadiene rubber. This intermediate layer can be formed using vacuum film formation, spin coating, or the like.

On the dye recording layer 12, a light reflection layer 14 is provided for the purpose of improving the reflectance. The material of the light reflection layer 14 may be a light reflective substance having a high reflectance to laser light, and the reflectance of the material is preferably 30% or more, more preferably 50% or more, and further preferably 70% or more. preferable. Examples include Mg, Se,
Y, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo,
W, Mn, Re, Fe, Co, Ni, Ru, Rh, P
d, 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. Preferred of these are:
Cr, Ni, Pt, Cu, Ag, Au, Al and stainless steel. These substances may be used alone or in combination of two or more. It can also be used as an alloy. As a material of the light reflection layer 14, A
u, Ag, Al or alloys thereof are particularly preferred. The light reflecting layer 14 can be formed, for example, by depositing, sputtering, or ion plating the light reflecting substance on the dye recording layer 12. Light reflection layer 1
The thickness of 4 is generally in the range of 10 to 800 nm, preferably in the range of 20 to 500 nm, more preferably in the range of 50 to 300 nm.

On the light reflecting layer 14, a protective layer 16 is provided for the purpose of physically and chemically protecting the dye recording layer and the like. A similar protective layer may be provided on the side of the transparent substrate 10 on which the dye recording layer 12 is not provided, for the purpose of improving scratch resistance and moisture resistance. As a material used for the protective layer 16, for example, SiO, SiO ₂ , MgF ₂ , SnO ₂ ,
Examples thereof include inorganic substances such as Si ₃ N _4, and organic substances such as thermoplastic resins, thermosetting resins, and UV curable resins.

The protective layer 16 can be formed, for example, by laminating a film obtained by extrusion of a plastic on the light reflecting layer 14 and / or the transparent substrate 10 with an adhesive layer. Alternatively, it may be provided by a method such as vacuum deposition, sputtering, or coating. 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 can also be formed by preparing a coating solution as it is or by dissolving it in an appropriate solvent, applying the coating solution, and irradiating with UV light to cure. Various additives such as an antistatic agent, an antioxidant, and a UV absorber may be added to these coating solutions according to the purpose.

The hardness of the protective layer 16 is preferably F or more, more preferably H or more in terms of scratch hardness of a pencil, in order to prevent uneven spread of pits in the direction of the protective layer. The thickness of the protective layer is preferably in the range of 2.5 to 23 μm, more preferably 3.5 to 20 μm, and still more preferably 4.0 to 15 μm.

Further, an intermediate layer may be provided between the light reflecting layer 14 and the protective layer 16 in order to adjust optical characteristics such as improvement in reflectance. As a material used for the intermediate layer,
For example, SiO, SiO ₂ , MgF ₂ , SnO ₂ , Si ₃ N
_And inorganic substances such as ₄ . Further, this intermediate layer can be formed by vacuum film formation such as evaporation or sputtering.

The recording of information on the optical information recording medium is performed, for example, as follows. The optical information recording medium of the present invention is 1x speed (1.2 to 1.2 times) of a normal CD format.
(1.4 m / sec), and 4 ×, 6 × or higher speed recording. First, the optical information recording medium is set to a predetermined linear velocity (1.
(2 to 1.4 m / sec) or a predetermined constant angular velocity while irradiating recording light such as semiconductor laser light from the substrate side. By this light irradiation, the dye recording layer absorbs the light and locally raises the temperature. For example, information is recorded by forming pits and changing the optical characteristics. 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.

As described above, in the CD-R type optical information recording medium according to the present embodiment, (1) the groove depth of the pre-groove formed on the transparent substrate is 150 to 200 nm; 2) satisfying the three requirements that the thickness of the dye recording layer is 50 to 160 nm and (3) the extinction coefficient k of the dye recording layer at the recording laser wavelength is 0.045 to 0.075. This makes it possible to achieve both good recording sensitivity and good recording characteristics (jitter). That is, even if the thickness of the dye recording layer is reduced to 50 to 160 nm, the organic dye contained in the dye recording layer is selected such that the extinction coefficient k at the recording laser wavelength is 0.045 to 0.075. By doing so, the groove depth of the pre-groove is 150 to 20
Good recording sensitivity and good jitter can be obtained in the range of 0 nm.

Further, by reducing the thickness of the dye recording layer, the time required for forming the dye recording layer (for example, the time required for application and drying such as spin coating time) is reduced.
The manufacturing efficiency of the optical information recording medium can be improved, and the cost can be reduced. Further, since the groove depth of the pre-groove is the same as the conventional one, the substrate can be easily formed.

In the above description, an example of a CD-R type optical information recording medium provided with a light reflecting layer and a protective layer has been described.
These layers are optional components, and a configuration without these layers may be adopted.

Although an example of a CD-R type optical information recording medium has been described above, the optical information recording medium of the present invention is applied to a DVD-R type optical information recording medium capable of higher density recording. You can also. A DVD-R type optical information recording medium is basically a CD-R type optical recording medium except that the track pitch of a pre-groove formed on a transparent substrate is 0.6 to 0.9 μm, which is narrower than that of a CD-R type. It has the same configuration as the optical information recording medium of the type.

Also, two laminates composed of a transparent substrate, a dye recording layer, a light reflection layer, and a protective layer formed in the same manner as the above-mentioned CD-R type optical information recording medium were prepared. Is laminated with an adhesive or the like so that each dye recording layer is on the inside, whereby a DVD-R type optical information recording medium having a laminated structure having two dye recording layers can be obtained. Also, a DVD having a dye recording layer on one side only is bonded to the laminate and a disc-shaped protective substrate having substantially the same size as the substrate of the laminate with an adhesive or the like so that the dye recording layer is on the inside. -An R-type optical information recording medium can be manufactured. In the case of a laminated structure, the transparent substrate has a diameter of 120 ± 3 mm and a thickness of 0.6.
One having a thickness of ± 0.1 mm is generally used, and the thickness of the optical information recording medium after bonding is adjusted to be 1.2 ± 0.2 mm.

When the optical information recording medium of the present invention is used as a DVD-R type medium, its characteristics appear more. That is, D
In the case of the VD-R type medium, higher density recording is required as compared with the CD-R type medium. However, in the present invention, the thickness of the dye recording layer is considerably thinner than the conventional one, so that it is suitable for high density recording. It is.

[0060]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The optical information recording medium of the present invention will be specifically described below based on embodiments. Example 1 A polycarbonate substrate having a spiral pre-groove formed on the surface by injection molding (thickness: 1.2 m)
m, outer diameter: 120 mm, inner diameter: 15 mm, Teijin Limited
(Trade name: Panlite AD5503).
The groove depth of the pregroove is 175 nm and the groove width is 50
0 nm and a track pitch of 1600 nm.

The following dye (A) 2 g and the following dye (B) 0.
6 g and 2,2,3,3-tetrafluoro-1-propanol in 100 ml of ultrasonic irradiation for 2 hours to dissolve the dye recording layer forming coating solution on the pre-groove surface of the obtained substrate. The coating was performed by a spin coating method while changing the number of rotations from 300 to 3000 rpm, and dried to form a dye recording layer. The thickness of the dye recording layer was 120 nm as measured by observing the cross section of the dye recording layer with a scanning electron microscope (SEM). In addition, 78 of the dye recording layer
The extinction coefficient k for the laser beam of 0 nm was 0.06.

[0062]

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Next, a light reflecting layer made of silver (Ag) having a thickness of about 90 nm was formed on the dye recording layer by DC sputtering in an argon atmosphere. Further, a UV curable resin (trade name “SD-318”, manufactured by Dainippon Ink and Chemicals, Inc.) is applied on the light reflecting layer at a rotational speed of 300 rpm or more.
The coating was performed by spin coating while changing the speed up to 4000 rpm. After the application, the coating was irradiated with ultraviolet light from a high-pressure mercury lamp to cure the coating, thereby forming a protective layer having a thickness of 8 μm.
The surface hardness of the protective layer was 2H as a pencil hardness.

Through the above steps, a CD-R type optical disk of Example 1 comprising a substrate, a dye recording layer, a light reflecting layer and a protective layer was manufactured. Example 2 A CD-R type optical disk according to the present invention was manufactured in the same manner as in Example 1 except that the groove width of the pregroove was 580 nm. Example 3 A CD-R optical disk according to the present invention was manufactured in the same manner as in Example 1 except that the groove width of the pregroove was 420 nm. Example 4 A CD-R type optical disk according to the present invention was produced in the same manner as in Example 1, except that the thickness of the dye recording layer was changed to 100 nm. Example 5 A CD-R type optical disk according to the present invention was produced in the same manner as in Example 1, except that the thickness of the dye recording layer was changed to 140 nm. [Comparative Example 1] Except that the dye was only the dye (B),
A comparative CD-R optical disk was manufactured in the same manner as in Example 1. At this time, the extinction coefficient k of the dye recording layer with respect to the 780 nm laser beam was 0.03. [Comparative Example 2] The dye (B) was added to 2 g of the dye (A).
A CD-R optical disc for comparison was produced in the same manner as in Example 1 except that 1.4 g was mixed. At this time, the extinction coefficient k of the dye recording layer with respect to the 780 nm laser beam is 0.1.
04. [Comparative Example 3] Except that the dye was only the dye (A),
A comparative CD-R optical disk was manufactured in the same manner as in Example 1. At this time, the extinction coefficient k of the dye recording layer with respect to the 780 nm laser beam was 0.08. Comparative Example 4 A comparative CD-R optical disk was manufactured in the same manner as in Example 1 except that the thickness of the dye recording layer was changed to 30 nm. Comparative Example 5 A comparative CD-R optical disk was manufactured in the same manner as in Example 1 except that the thickness of the dye recording layer was changed to 180 nm. Comparative Example 6 A comparative CD-R optical disk was manufactured in the same manner as in Example 1, except that the groove depth of the pregroove was 140 nm. Comparative Example 7 A comparative CD-R optical disk was produced in the same manner as in Example 1, except that the groove depth of the pregroove was 210 nm. [Evaluation as Optical Disk] C in Examples and Comparative Examples
After recording on a DR optical disk at a wavelength of 780 nm of a laser beam using an evaluator “OMT2000” (manufactured by Pulstec), 3T pit jitter was measured for the optical disk after recording. The smaller the value of the 3T pit jitter is, the smaller the pit variation is. If the value of the jitter is 35 or less, it can be said that the recording / reproducing characteristics are good.
Further, the recording power at which the optimum jitter was exhibited was measured. This recording power indicates the recording sensitivity. If the recording power is 8 mW or less, it can be said that the recording sensitivity is good. Table 1 shows the obtained results.

[0065]

[Table 1]

From the results shown in Table 1, in the case of the CD-R type optical disk according to the present invention (Examples 1 to 6), the value of the 3T pit jitter is as small as 31 or less, and good recording / reproducing characteristics can be obtained. And the recording power is 8mW
The results are as follows, indicating that the recording medium has good recording sensitivity. On the other hand, a comparative CD-R optical disk (Comparative Examples 1 to 5)
In the case of (3, 5 to 7), it can be seen that satisfactory recording / reproducing characteristics cannot be obtained, for example, the value of the 3T pit jitter is as large as 36 or more, and reading errors of digital signals are likely to occur. Also, in the case of the comparative CD-R type optical disc (Comparative Examples 1 to 3, 5 to 7), it is found that the required recording power is too large to perform recording under normal recording conditions. When the dye recording layer was too thin, the laser light was not sufficiently absorbed, the sensitivity was extremely low, and it was difficult to form pits (Comparative Example 4).

[0067]

The optical information recording medium of the present invention has the effects of good recording sensitivity and good recording characteristics (jitter).

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing a laminated structure of a CD-R type optical information recording medium according to an embodiment of the present invention.

FIG. 2 is a schematic sectional view illustrating a shape of a pregroove.

FIG. 3 is a schematic sectional view illustrating a shape of a dye recording layer.

[Explanation of symbols]

 D Groove depth W Groove width 10 Transparent substrate plate 12 Dye recording layer 14 Light reflection layer 16 Protective layer

Claims (1)

[Claims] 1. A transparent substrate on which a pregroove having a groove depth of 150 to 200 nm is formed has a thickness of 50 to 160 nm.
And the extinction coefficient k at the recording laser wavelength is 0.04.
An optical information recording medium having a dye recording layer on which information can be recorded by containing an organic dye selected to be 5 to 0.075.