JP2663009B2 - Information recording medium and method of manufacturing the same - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to an information recording medium on which information can be written and / or read using a high energy density laser beam, and a method for manufacturing the same.

[Technical Background of the Invention] In recent years, information recording media using a beam of high energy density such as laser light have been developed and put into practical use. This information recording medium is called an optical disk,
It is used as a disk, an audio disk, a large-capacity still image file, and a disk memory for a large-capacity computer.

The optical disk has a basic structure of a disk-shaped substrate made of glass, synthetic resin, etc., and Bi, Sn,
A recording layer made of a metal or semimetal such as In or Te; or a dye such as cyanine, metal complex, or quinone.
In general, an intermediate layer made of a polymer substance is provided on the surface of the substrate on which the recording layer is provided, from the viewpoint of improving the surface properties of the substrate, improving the adhesion to the recording layer, or improving the sensitivity of the optical disc. Is often done.

Further, for the purpose of improving the durability of the information recording medium, a protective layer is provided on the recording layer, or as a disk structure, a recording layer is provided on at least one of the two disc-shaped substrates, An air sandwich structure has been proposed in which the two substrates are joined via a ring-shaped inner spacer and a ring-shaped outer spacer so that the recording layer is located inside and a space is formed. In an optical disk provided with such a protective layer or an optical disk having an air sandwich structure, the recording layer does not come into direct contact with the outside air, and information is recorded and reproduced by laser light transmitted through the substrate. This has the advantage that it does not suffer physical or chemical damage, or dust adheres to its surface and does not hinder the recording and reproduction of information.

Writing and reading of information to and from the optical disk are usually performed by the following method.

Writing of information is performed by irradiating a laser beam to the optical disk through the substrate, and the irradiated portion of the recording layer absorbs the light and locally raises the temperature, causing a physical or chemical change (for example, a pit change). Information) is recorded by altering its optical properties. Reading of information is also performed by irradiating a laser beam to the optical disk through the substrate, and the information is reproduced by detecting reflected light or transmitted light corresponding to a change in the optical characteristics of the recording layer.

As the recording material for forming the recording layer of such an information recording medium, metals and dyes are known as described above. An information recording medium using a dye has advantages in characteristics of the recording medium itself, such as higher sensitivity than a recording material such as a metal, and also has a manufacturing advantage that a recording layer can be easily formed by a coating method. Has great advantages. However, a recording layer made of a dye generally has a drawback that the reflectance is low. Therefore, a metal reflective layer is often provided on the dye recording layer for the purpose of improving the reflectance. Further, a protective layer is provided on the reflective layer to further protect these layers. The protective layer is advantageous in that the production is simpler and the production cost is lower than that of a method of making the structure of the disk a sandwich structure, which is another method of protection.

The method of forming a recording layer composed of a dye is performed by coating and drying as described above. The coating method is generally applied using a spin coater because a uniform thin film needs to be formed on the disc-shaped resin substrate. When a coating solution for forming a dye layer for forming a dye layer is applied onto the substrate, it is usually applied to almost the entire surface of the substrate. Due to its characteristics, the spin coater can apply the coating at a position where the coating on the inner peripheral side of the substrate is limited to a certain extent, but cannot control the coating range on the outer peripheral side. In addition, it cannot be said that the coating start position on the inner peripheral side is not applied inside the position, and the coating liquid for forming a dye layer is applied to almost the entire surface of the substrate. Further, a metal reflective layer is provided thereon. The reflection layer is provided mainly for improving the reflectance,
It is generally provided inside the outer peripheral edge of the substrate, that is, inside the dye recording layer. Then, a protective layer such as a UV curable resin is provided on the reflective layer by coating, for example, to protect the recording layer and the reflective layer.

In the optical disk having such a structure, the protective layer is formed directly on the dye on the outer peripheral side of the substrate. In this case, when the coating solution for forming the protective layer is applied on the dye layer, the coating solution erodes the dye layer, so that the obtained optical disc has poor appearance, reduced adhesion of the protective layer, and further deterioration of recording characteristics. Bring.

Further, when the reflective layer is covered not on the inside of the recording layer but on the entire surface of the dye recording layer, there is a problem that the adhesion between the protective layer and the reflective layer provided thereon is not particularly good.

Therefore, an information recording medium in which a dye recording layer, a reflective layer, and a protective layer are provided on a substrate in this order according to a known technique cannot be said to have sufficiently excellent characteristics.

[Object of the Invention] The present invention provides information having good appearance, improved durability and excellent recording / reproducing characteristics in which a dye recording layer, a reflective layer and a protective layer are provided in this order on a resin substrate. It is intended to provide a recording medium.

Another object of the present invention is to provide a method for easily manufacturing the information recording medium.

[Summary of the Invention] The present invention relates to a dye recording layer provided on a disk-shaped resin substrate in an annular shape and capable of writing information with a laser, and an inner peripheral edge and an outer periphery on the annular recording layer, respectively. An annular reflective layer laminated so that the side edges coincide with each other; an inner peripheral edge and an outer peripheral edge extend beyond the inner peripheral edge and the outer peripheral edge of the reflective layer, respectively; An information recording medium is characterized by including a protective layer provided by coating on the reflective layer so as to contact the surface.

The information recording medium may further include a step of coating and forming a dye recording layer on which information can be written by a laser on a disc-shaped resin substrate; a step of forming an annular reflection layer on the recording layer; Removing the exposed portion of the dye recording layer existing in an area other than the area provided, so as to extend over the inner peripheral edge and the outer peripheral edge of the reflective layer so as to contact the surface of the disc-shaped substrate. The method can be advantageously obtained by a method for producing an information recording medium, which comprises a step of applying and forming a protective layer on the reflective layer.

Preferred embodiments of the information recording medium of the present invention are as follows.

1) An information recording medium, wherein the dye is at least one dye selected from a cyanine dye, an azulenium dye, a phthalocyanine dye, an imidazoquinoxaline dye, and a squalilium dye.

2) The information recording medium, wherein the material of the resin substrate is polycarbonate, polyolefin, or cell cast polymethyl methacrylate.

3) The material of the reflective layer is Au, Ag, Cu, Ni, Pt, Cr, Ti
And the at least one metal selected from the group consisting of Al and Al.

4) The information recording medium, wherein the material of the protective layer is made of a UV curable resin.

Preferred embodiments of the method for producing an information recording medium of the present invention are as follows.

1) The method for manufacturing an information recording medium, wherein the coating of the dye layer is performed using a spin coater.

2) The method for manufacturing an information recording medium, wherein the protective layer is provided by coating.

[Effects of the Invention] The information recording medium of the present invention, for example, removes the dyes in the inner and outer peripheral regions where the reflective layer is not provided to expose the substrate surface below the dye layer, This is performed by forming the surroundings of the subsequent protective layer so as to directly contact the substrate. The information recording medium thus obtained is
The adhesion between the dye recording layer and the reflection layer and the adhesion between the reflection layer and the protective layer are remarkably improved. This is because the protective layer is in direct contact with the substrate on the inner peripheral side and the outer peripheral side, so that a strong adhesive force can be obtained at this portion. As described above, the adhesiveness between the dye recording layer and the reflective layer and between the reflective layer and the protective layer is significantly improved, so that the durability as an information recording medium is greatly improved.

Furthermore, since the protective layer is not in direct contact with the dye recording layer, the dye recording layer does not attack when the protective layer is applied, so that the appearance of the obtained information recording medium becomes good, and the recording characteristics are also C / N. Etc. are improved. Therefore, it can be said that the information recording medium of the present invention has good appearance, and has improved durability and excellent recording / reproducing characteristics.

In the process of manufacturing the information recording medium of the present invention, after providing the reflective layer on the dye recording layer, the step of removing the dye recording layer in an area other than the reflective layer is simply spraying a solvent over the entire surface of the removed surface. Can be performed. Therefore, it can be said that the information recording medium of the present invention can be obtained by a simple and easy method by employing these methods.

[Detailed Description of the Invention] The information recording medium of the present invention has a basic configuration in which a dye recording layer, a reflective layer and a protective layer are provided in this order on a substrate. In such a configuration, the dye recording layer is easy to manufacture and has high sensitivity, the reflective layer improves the low reflectivity, which is a drawback of the dye layer, and the protective layer protects the two layers and optical disc Each of the three layers has the role of improving the durability. And they are based on the idea that they share their functions.

In order to manufacture an information recording medium having the above configuration, first, a recording layer made of a dye is generally applied using a spin coater as described above. Due to its characteristics, the spin coater can apply the coating at a position where the coating start position on the inner peripheral side of the substrate is limited to some extent, but cannot control the coating range on the outer peripheral side. In addition, it cannot be said that the coating start position on the inner peripheral side is not coated on the inner side, and the coating liquid for forming the dye layer is almost completely coated on the substrate. The reflective layer provided thereon is generally provided inside the dye recording layer. Then, a protective layer such as a UV curable resin is provided on the reflective layer by coating. Therefore, the protective layer is formed directly on the dye layer on the outer peripheral side of the substrate. According to the study of the present inventors, when a coating solution for forming a protective layer is applied on a dye layer, there is a problem that the coating solution is apt to attack the dye layer. It has been clarified that the adhesion of the layer is reduced and the recording characteristics are deteriorated.

In addition, it was also found that when the reflective layer was covered not on the inside of the recording layer but on the entire surface of the dye recording layer, there was a problem that the adhesion between the protective layer and the reflective layer provided thereon was not good. did.

The present inventor has conducted various studies to improve the adhesion of the protective layer, and as a result, it has been found that the inner side of the dye recording layer and the outer side of the inner side edge of the dye recording layer coated on almost the entire surface of the substrate. On the layer, provided a reflective layer made of metal, by removing the exposed portion of the dye recording layer remaining in the region other than where the reflective layer was provided, to expose the substrate surface under the dye recording layer, It has been found that by forming the protective layer provided thereon so that the periphery thereof is in direct contact with the substrate, it is possible to obtain an information recording medium having good appearance and improved adhesion and recording characteristics of the protective layer.

The method for manufacturing an information recording medium of the present invention is performed, for example, as follows. This will be described in detail with reference to the attached FIGS.

FIG. 1 shows a disc-shaped resin substrate 11 having a hole 10 in the center,
A recording layer 12 made of a dye provided thereon by coating and a region not partially coated near the periphery of the hole 10
FIG. 13 is a partial cross-sectional view consisting of FIG. On the disc-shaped resin substrate 11,
The dye recording layer forming coating solution is applied using spin coating to form a recording layer 12 made of a dye. The area of the uncoated region 13 varies depending on the conditions at the time of application, and generally, it is not possible to secure a sufficient area to improve the adhesion of a later protective layer or the like. When the coating method is performed by a roll coater other than spin coating, dipping, or the like, the uncoated region 13 does not usually exist.

FIG. 2 shows a disc-shaped resin substrate 21 having a hole 20 in the center,
A recording layer 22 made of a dye provided thereon by coating,
A portion formed of a metal reflective layer 25 provided in an area other than the inner non-recording area 23 provided on the peripheral edge of the hole 20 and the inner peripheral non-recording area 24 provided on the inner peripheral edge. It is sectional drawing. A reflective layer 25 made of metal is formed on the recording layer 12 made of the dye shown in FIG. 1 by vapor deposition or the like. that time,
The reflective layer 25 is provided in an area other than the inner peripheral non-recording area 23 provided on the peripheral edge of the hole of the substrate 21 and the inner peripheral non-recording area 24 provided inside the outer peripheral edge. For this reason, the vicinity of the inner and outer edges of the dye recording layer 22 is not covered with the reflective layer 25. In order to secure the inner non-recording area 23 and the outer non-recording area 24, the formation of such a reflective layer 25 is usually performed by performing evaporation or the like using this portion as a mask.

FIG. 3 shows a disc-shaped resin substrate 31 having a hole 30 in the center,
A recording layer 32 made of a dye provided by coating on a substrate,
The reflective layer 35 provided thereon, the inner peripheral non-recording area 33 provided on the peripheral edge of the hole 30, and the outer peripheral non-recording area 34 provided inside the outer peripheral edge (the dye recording layer also includes FIG. 4 is a partial cross-sectional view of the light-emitting device (having no reflective layer). The dye recording layer 22 near the periphery of the hole and the periphery of the substrate in FIG. 2, that is, the dye recording layer 22 applied to the inner non-recording area 23 and the outer non-recording area 24 is removed. Then, the substrate surface is exposed, and the inner peripheral side non-recording area 33 and the outer peripheral side non-recording area 34 of the surface of the substrate are provided outside the peripheral edge of the hole 30 in FIG. 3 and inside the outer peripheral edge, respectively. . The method for removing the dye coating layer can be easily performed by spraying a solvent by spin coating or the like on the entire surface of the substrate provided with the reflection layer and the like. Other examples include a method of wiping the dye coating layer with a solvent or a method of drying the dye coating layer and burning it off with a laser to remove it.

FIG. 4 is a diagram showing a characteristic configuration of the information recording medium of the present invention. That is, FIG. 4 shows a disc-shaped resin substrate 41 having a hole 40 in the center, a recording layer 42 made of a dye provided by coating on the substrate, a reflective layer 45 provided thereon, and further a FIG. 4 is a partial cross-sectional view of an information recording medium including a protective layer provided. The protective layer 46 is provided by coating on the entire surface of the reflective layer 45 and almost the entire inner non-recording area 33 and outer non-recording area 34 in FIG. Accordingly, the dye recording layer 42 and the reflection layer 45 are completely covered by the protective layer 46.

After forming the reflective layer, the information recording medium manufactured in this manner removes the dye in the inner and outer peripheral areas where the reflective layer is not provided, exposing the substrate surface below the dye layer. Then, a subsequent protective layer is applied and formed so that the periphery thereof is in direct contact with the substrate. Therefore, the adhesiveness between the dye recording layer and the reflective layer and the adhesiveness between the reflective layer and the protective layer are remarkably improved. This is because the protective layer completely covers and protects the dye recording layer and the reflective layer, and can directly contact the substrate on the inner peripheral side and the outer peripheral side to obtain a strong adhesive force in this part. It is. As described above, since the protective layer completely covers and protects the dye recording layer and the reflective layer, and the adhesion of the protective layer to the substrate is remarkably improved, the information recording medium of the present invention is durable. Sex has been greatly improved. Further, since the protective layer does not directly contact the dye recording layer, the dye recording layer does not attack when the coating liquid for forming the protective layer is applied, so that the appearance of the obtained information recording medium is improved, and the recording characteristics are also improved. / N etc. are improved. Therefore, the information recording medium of the present invention has a good appearance, and has improved durability and excellent recording / reproducing characteristics.

The production of the information recording medium of the present invention can be performed using, for example, the materials described below.

The resin substrate used in the present invention can be arbitrarily selected from various plastic materials used as a substrate of a conventional information recording medium. In view of the optical characteristics, flatness, workability, handleability, stability over time, and manufacturing cost of the substrate, examples of the substrate material include acrylic resins such as cell cast polymethyl methacrylate and injection-molded polymethyl methacrylate; Examples thereof include vinyl chloride resins such as vinyl chloride and vinyl chloride copolymer; epoxy resins; polycarbonate resins, amorphous polyolefins and polyesters. Preferably, polycarbonate, polyolefin and cell cast polymethyl methacrylate can be mentioned.

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, improving solvent resistance of the substrate, 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-methylolacrylamide, styrene / vinyltoluene copolymer, and chlorosulfonate. Polyethylene, nitrocellulose, polyvinyl chloride, chlorinated polyolefin, polyester, polyimide, vinyl acetate-vinyl chloride copolymer, ethylene-vinyl acetate copolymer, polyolefin,
Polymer substances such as polypropylene and polycarbonate; organic substances such as silane coupling agents; and inorganic substances such as inorganic oxides (SiO ₂ and Al ₂ O ₃ ) and inorganic fluorides (MgF ₂ ).

The undercoat layer is prepared, for example, by dissolving or dispersing the above substance in an appropriate 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 be formed. The thickness of the undercoat layer is generally 0.005 to 20 μm
And preferably in the range of 0.01 to 10 μm.

Further, a pre-groove layer and / or a pre-pit layer may be provided on the substrate (or the undercoat layer) for the purpose of forming irregularities representing information such as tracking grooves or address signals. As a material for the pregroove layer or the like, 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 pre-groove layer is formed by first applying a mixed solution composed of the above-mentioned acrylate and a polymerization initiator on a precisely formed master (stamper), and then placing a substrate on the coating solution layer. The liquid layer is cured by irradiating ultraviolet rays through the substrate or the matrix to fix the substrate and the liquid phase. Next, the substrate provided with the pre-groove layer is obtained by peeling the substrate from the matrix. The thickness of the pregroove layer is generally in the range of 0.05 to 100 μm, preferably in the range of 0.1 to 50 μm. When the substrate material is plastic as in the present invention, the substrate may be directly provided with pregrooves and / or prepits by injection molding or extrusion molding.

On a substrate (or a pre-groove layer or the like), a recording layer made of a dye is provided. The dye used in the present invention is not particularly limited, and any dye may be used. For example, cyanine dyes, phthalocyanine dyes, pyrylium and thiopyrylium dyes, azulenium dyes, squarylium dyes, metal complex salt dyes such as Ni and Cr, naphthoquinone and anthraquinone dyes, indophenol dyes, and indoaniline dyes And triphenylmethane dyes, triallylmethane dyes, aluminum / diimmonium dyes, and nitroso compounds.

Among these, a dye having a high absorptivity to light in the near-infrared region of 700 to 900 nm is preferable because a semiconductor laser that emits near-infrared light is practically used as a recording / reproducing laser.

Preferred examples thereof include: i) cyanine dyes: [1] (CH ₃ ) ₂ N— (CHCHCH) ₅ —CH = ⁺ N (CH ₃ ) ₂ ClO ₄ ⁻ (Where n is 2 or 3) (Where R is a hydrogen atom or N (CH ₃ ) ₂ ) [4] Φ ⁺ -L = Ψ (X ^m− ) _{1 / m} (where Φ and Ψ are each a condensed aromatic ring Indolenine ring residue, thiazole ring residue, oxazole ring residue, selenazole ring residue, imidazole ring residue, pyridine ring residue, thiazolopyrimidine ring residue or imidazoquinoxaline ring residue, L is A linking group for forming monocarbocyanine, dicarbocyanine, tricarbocyanine or tetracarbocyanine, X ^m- is a m-valent anion, m is 1 or 2, and X ^m- is May be substituted on Φ, L or Ψ to form an inner salt, or Φ and L or L and Ψ may be further linked to form a ring) Examples of typical compounds include the following a) to h) And the like.

ii) Squalilium dyes: iii) Azulhenium dyes: (However, at least one combination of R ¹ and R ² , R ² and R ³ , R ³ and R ⁴ , R ⁴ and R ⁵ , R ⁵ and R ^6, and R ⁶ and R ⁷ is substituted or unsubstituted. R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ when forming a ring with a substituted heterocyclic or aliphatic ring and not forming the ring
And R ⁷ are each a hydrogen atom, a halogen atom or a monovalent organic residue, or R ¹ and R ² , R ³ and R ⁴ , R ⁴ and R ⁵ ,
At least one combination of R ⁵ and R ⁶ and R ⁶ and R ⁷ may form a substituted or unsubstituted aromatic ring, and A is a divalent organic residue linked by a double bond. And Z ^- is an anionic residue. Note that at least one carbon atom constituting the azulene ring may be replaced with a nitrogen atom to form an azaazulene ring. Iv) Indophenol dyes: (Where X and Y are each a hydrogen atom, an alkyl group, an acylamino group, an alkoxy group or a halogen atom, and R ¹ , R ² and R ³ are each a hydrogen atom, C ₁ -C ₂₀
A substituted or unsubstituted alkyl group, aryl group, heterocyclic ring or cyclohexyl group, wherein A is -NHCO- or-
CONH-) v) Metal complex dyes: (Where R ^{1 to} R ⁴ are an alkyl group or an aryl group, respectively, and M is a divalent transition metal atom) (Where R ¹ and R ² are an alkyl group or a halogen atom, respectively, and M is a divalent transition metal atom) (However, R ¹ and R ² are each a substituted or unsubstituted alkyl group or aryl group, and R ³ is an alkyl group, a halogen atom or (Where R ⁴ and R ⁵ are each a substituted or unsubstituted alkyl group or aryl group), M is a transition metal atom, and n is an integer of 0 to 3. (Where [Cat] is a cation necessary to neutralize the complex salt, M is Ni, Cu, Co, Pd or Pt, and n is 1 or 2) (Where [Cat] is a cation necessary to neutralize the complex salt, M is Ni, Cu, Co, Pd or Pt, and n is 1 or 2) (Where X is a hydrogen atom, a chlorine atom, a bromine atom or a methyl group, n is an integer of 1 to 4, and A is a quaternary ammonium group) (Where X ¹ and X ² are each a nitro group and / or a halogen atom, n ₁ and n ₂ are each an integer of 1 to 3, R ¹ and R ² are an amino group, a monoalkylamino group, X ¹ and X ² , n ₁ and n _2, and R ¹ and R ² may be the same or different even if they are the same as dialkylamino, acetylamino, and benzoylamino (including substituted benzoylamino). M is Cr or
A Co atom and Y is hydrogen, sodium, potassium, ammonium, aliphatic ammonium (including substituted aliphatic ammonium) or alicyclic ammonium) vi) naphthoquinone-based, anthraquinone-based dyes: (Where R is a hydrogen atom, an alkyl group, an allyl group, an amino group or a substituted amino group) (Where R is a hydrogen atom, an alkyl group, an allyl group, an amino group or a substituted amino group) (Where R is a hydrogen atom, an alkyl group, an allyl group, an amino group or a substituted amino group) (Where X is a halogen atom and n is an integer of 0 to 10) (Where X is a halogen atom) And the like.

Among these dyes, those to which the method of the present invention can be preferably applied are cyanine dyes, azurenium dyes, squalilium dyes, phthalocyanine dyes and imidazoquinoxaline dyes. These dyes may be used alone or as a mixture of two or more. When a cyanine dye is used, the metal complex salt dye or the aminium / diimmonium dye may be used together as a quencher.

The recording layer is formed by dissolving the dye and, if desired, a binder in a solvent to prepare a coating solution, and then applying the coating solution to the substrate surface to form a coating film and then drying the coating solution. Can be.

Ethyl acetate, as a solvent for the dye coating solution preparation,
Esters such as butyl acetate and cellosolve acetate; ketones such as methyl ethyl ketone, cyclohexanone and methyl isobutyl ketone; halogenated hydrocarbons such as dichloromethane, 1,2-dichloroethane and chloroform; ethers such as tetrahydrofuran, ethyl ether and dioxane; ethanol; n- Examples thereof include alcohols such as propanol, isopropanol and n-butanol, amides such as dimethylformamide, and fluorine-based solvents such as 2,2,3,3 and tetrafluoropropanyl. These non-hydrocarbon organic solvents account for 50% by volume.
As long as it is within, it may contain a hydrocarbon-based solvent such as an aliphatic hydrocarbon solvent, an alicyclic hydrocarbon solvent, or an aromatic hydrocarbon solvent.

Antioxidants, UV absorbers, plasticizers,
Various additives such as a lubricant may be added according to the purpose.

When a binder is used, examples of the binder include cellulose derivatives such as gelatin, nitrocellulose, and cellulose acetate; natural organic polymer substances such as dextran, rosin, and rubber; and carbonized materials such as polyethylene, polypropylene, polystyrene, and polyisobutylene. Hydrogen resin, polyvinyl chloride, polyvinylidene chloride, polyvinyl chloride
Vinyl resins such as polyvinyl acetate copolymer, acrylic resins such as polymethyl acrylate and polymethyl methacrylate, polyvinyl alcohol, chlorinated polyolefin, epoxy resin, butyral resin, rubber derivative phenol.
Synthetic organic polymer substances such as precondensates of thermosetting resins such as formaldehyde resins can be mentioned.

Examples of the 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.

When a binder is used as a material for the recording layer, the ratio of the dye to the binder is generally in the range of 0.01 to 99% (weight ratio), preferably in the range of 1.0 to 95% (weight ratio).

The recording layer may be a single layer or a multilayer, but the layer thickness is generally
It is in the range of 0.01 to 10 μm, preferably in the range of 0.02 to 1 μm. The recording layer may be provided not only on one side of the substrate but also on both sides.

The reflective layer of the present invention is provided on the dye recording layer. By providing the reflection layer, in addition to the effect of improving the reflectance, the effect of improving the S / N at the time of reproducing information and the effect of improving the sensitivity at the time of recording can be obtained.

The light-reflective substance that is the material of the reflective layer is a substance having a high reflectance to laser light, and examples thereof include Mg, Se,
Y, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Re, F
e, Co, Ni, Ru, Rh, Pd, Ir, Pt, Cu, Ag, Au, Zn, C
Metals and metalloids such as d, Al, Ga, In, Si, Ge, Te, Pb, Po, Sn and Bi can be mentioned. Among these, Au, Ag, Cu, Pt, Al, Cr and Ni are preferred. These substances may be used alone or in combination of two or more kinds or as an alloy.

The reflection layer can be formed on the recording layer by, for example, vapor deposition, sputtering, or ion plating of the above-mentioned light reflective substance. The thickness of the reflective layer is generally in the range from 100 to 3000 °.

A protective layer is provided on the reflective layer for the purpose of physically and chemically protecting the recording layer and the entire information recording medium. This protective layer also has the effect of increasing the scratch resistance and moisture resistance on the side of the substrate where the recording layer is not provided.

Examples of the material used for the protective layer include a thermoplastic resin, a thermosetting resin, a UV-curable resin, and the like, and preferably a UV-curable resin. In the present invention, it can be provided by applying the above substance.

That is, it can also be formed by dissolving a thermoplastic resin, a thermosetting resin, or the like in an appropriate solvent to prepare a coating solution, applying the coating solution, and drying.
In the case of a UV curable resin, a coating solution is prepared as it is or dissolved in an appropriate solvent, and then this coating solution is applied.
It can also be formed by curing by irradiating UV light. UV curable resins include oligomers of (meth) acrylates such as urethane (meth) acrylate, epoxy (meth) acrylate, and polyester (meth) acrylate, and monomers such as (meth) acrylic acid ester, and a photopolymerization initiator. And the like can be used. Various additives such as an antistatic agent, an antioxidant and a UV absorber may be added to these coating solutions according to the purpose. In the present invention, it is preferable to use a UV curable resin.

 The thickness of the protective layer is generally in the range from 0.1 to 100 μm.

Hereinafter, Examples and Comparative Examples of the present invention will be described. However, these examples do not limit the present invention.

[Example 1] 1 g added with 0.01 mol% was dissolved in 2,2,3,3-tetrafluoropropanol, and the dye recording layer coating solution (concentration: 2.7
5% by weight).

On a disc-shaped polycarbonate substrate (outer diameter: 130 mm, inner diameter: 15 mm, thickness: 1.2 mm, track pitch: 1.6 μm, groove depth: 800 mm) provided with a tracking guide,
After applying the coating solution at a rotation speed of 1000 rpm by a spin coating method, the coating layer was dried at a temperature of 70 ° C. for 10 minutes to form a recording layer having a thickness of 1200 °.

Au was deposited on the dye recording layer to form a reflective layer having a thickness of 1300 °. At this time, as shown in the attached FIG. 2, the reflective layer is provided on the inner peripheral non-recording area 23 provided on the peripheral edge of FIG. 2 and the inner peripheral non-recording area provided on the inner side of the outer peripheral edge. In order to provide them, evaporation was performed using a mask.

A solvent of 2,2,3,3-tetrafluoropropanol is sprayed onto the surface of the substrate on which the reflective layer and the like are provided by spin coating to remove a dye recording layer remaining in a region other than the region where the reflective layer is provided. Removed. As a result, the outer periphery of the hole of the substrate, which corresponds to the inner peripheral non-recording area 33 provided at the peripheral edge of FIG. 3 and the inner peripheral non-recording area 34 provided inside the outer peripheral edge, is 10 mm outside the periphery of the hole of the substrate. And a region 1.5 mm inward from the outer peripheral edge formed a region where the substrate surface was exposed.

On the reflective layer, a UV curable resin (trade name: 3070, manufactured by Three Bond Co.) was applied as a protective layer at a rotation speed of 1500 rpm by a spin coating method, and then cured by irradiating ultraviolet rays with a high-pressure mercury lamp, A protective layer having a thickness of 1 μm was formed. The protective layer was provided on the reflective layer by a spin coater as shown in FIG. 4 and over the entire inner non-recording area 33 and outer non-recording area 34 in FIG.

Thus, an information recording medium including the substrate, the dye recording layer, the reflective layer, and the protective layer was manufactured.

Comparative Example 1 An information recording medium was prepared in the same manner as in Example 1 except that the dye recording layer remaining in the area other than the area where the reflective layer was provided was not removed by spraying with a solvent by spin coating. Was manufactured.

The above configuration is as shown in FIG. FIG. 5 shows a disc-shaped resin substrate 51 having a hole 50 in the center, a recording layer 52 made of a dye provided by coating on the substrate, a reflective layer 55 provided thereon, and further provided on the reflective layer. 6 is a partial cross-sectional view including a protective layer 56 provided.

Comparative Example 2 An information recording medium was manufactured in the same manner as in Example 1, except that the reflective layer was provided on the recording layer and on the entire surface of the substrate without using a mask.

The above configuration is as shown in FIG. FIG. 6 shows a disc-shaped resin substrate 61 having a hole 60 in the center, a recording layer 62 made of a dye provided by coating on the substrate, a reflective layer 65 provided thereon, and further provided on the reflective layer. 6 is a partial cross-sectional view including a protective layer 66 provided.

[Evaluation of Information Recording Medium] 1) The appearance of the information recording medium obtained above was visually observed.

2) For the information recording medium obtained above, the laser power (recording power) for recording was 6 mW and the linear velocity was 1.3 m /
Recording was performed at seconds and a modulation frequency of 720 kHz, and the C / N was measured using a spectrum analyzer (TR4135: manufactured by Advantest) with a resolution bandwidth of 30 kHz and a reproduction power of:
The test was performed at 0.5 mW.

3) The information recording medium obtained above was stored for 10 days (80 ° C., 80% RH), and then the C / N was measured in 2) above.

Table 1 shows the obtained results.

As shown in Table 1, the information recording medium of Example 1 is higher than the conventional information recording media (Comparative Examples 1 and 2).
C / N is obtained, recording and reproducing characteristics are excellent, and appearance is good. In addition, since the adhesiveness is excellent, the C / N after storage is good, and it can be seen that the durability is excellent.

On the other hand, in Comparative Example 1, since the protective layer affected the dye recording layer,
Poor in appearance, C / N, and durability. In Comparative Example 2, the adhesion between the reflective layer and the protective layer is poor, and the protective layer is partially floating, and thus has a problem in durability in particular.

[Brief description of the drawings]

FIGS. 1, 2, and 3 are schematic partial cross-sectional views illustrating a method for manufacturing an information recording medium according to the present invention, and FIG. 4 is a configuration of the information recording medium according to the present invention. FIG. 5 and 6 are partial cross-sectional views showing the configuration of a conventional information recording medium shown in a comparative example. 10, 20, 30, 40, 50, 60: holes 11, 21, 31, 41, 51, 61: disc-shaped resin substrate 12, 22, 32, 42, 52, 62: dye recording layer 13: partially Non-coated areas 23, 33: inner non-recording area 24, 34: outer non-recording area 25, 35, 45, 55, 65: reflective layer 46, 56, 66: protective layer

 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-57-172545 (JP, A) JP-A-57-172549 (JP, A) JP-A-58-111141 (JP, A) 95740 (JP, A) JP-A-61-39949 (JP, A) JP-A-63-113831 (JP, A)

Claims (3)

(57) [Claims] 1. A dye recording layer provided on a disk-shaped resin substrate in an annular shape on which information can be written by a laser, wherein an inner peripheral edge and an outer peripheral edge are formed on the annular recording layer. An annular reflective layer laminated so as to match, the inner peripheral edge and the outer peripheral edge extend beyond the inner peripheral edge and the outer peripheral edge of the reflective layer, respectively, and come into contact with the disk-shaped substrate surface. An information recording medium comprising a protective layer provided by coating on the reflective layer as described above. 2. The information recording medium according to claim 1, wherein said dye recording layer is formed by coating. 3. A step of applying and forming a dye recording layer on which information can be written by a laser on a disk-shaped resin substrate; a step of forming an annular reflection layer on the recording layer; and providing the annular reflection layer. Removing the exposed portion of the dye recording layer existing in an area other than the above, and a protective layer extending beyond the inner peripheral edge and the outer peripheral edge of the reflective layer so as to contact the disk-shaped substrate surface. A process of applying and forming a film on the reflective layer.