JPH032091A - Information recording medium and optical information recording - Google Patents

Abstract

PURPOSE:To increase reflection factor or improve C/N signal recording properties by laminating a color recording layer consisting of specific cyanine color and a color with a specific extreme wavelength range of absorption and a reflection layer of metal in that order on a disc substrate. CONSTITUTION:An application liquid is prepared by dissolving the following materials in a solvent: cyanine color with a skeleton of naphthoindorenin expressed by formula I (R<1>, R<2>, R<3> are an alkyl group, an allyl group and an alkenyl group which can have a substitution group; X is an anion) and a color with an extreme wavelength range of light absorption of 750 to 900 nm as a color film, and if required, a binder. This application liquid is applied to the surface of a disc substrate, and this applied liquid is dried to form a color recording layer. After this, a reflection layer is formed on the color recording layer with a material of high reflection factor against laser beam using sputtering technique, and thus an information recording medium is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of the Invention] The present invention relates to an information recording medium and an optical information recording method on which information can be written and/or read using a high energy density laser beam.

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

The basic structure of an optical disk is a disk-shaped substrate made of glass, synthetic resin, etc., and Bi, Sn, etc.
, In, Te, and other metals or metalloids; or cyanine-based, metal complex-based, quinone-based, and other dyes. Note that an intermediate layer made of a polymeric substance is usually provided on the surface of the substrate on the side where the recording layer is provided, in order to improve the flatness of the substrate, improve the adhesive force with the recording layer, or improve the sensitivity of the optical disc. often.

In addition, for the purpose of improving the durability of the information recording medium, a protective layer is provided on the recording layer, or a recording layer is provided on at least one of the two disk-shaped substrates as a disk structure. An air sandwich structure has been proposed in which these 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 optical discs provided with such a protective layer or optical discs with an air sandwich structure, the recording layer is not in direct contact with the outside air, and information is recorded and reproduced using laser light that passes through the substrate. It has the advantage that it will not be physically or chemically damaged, or that dust will not adhere to its surface, which will impede information recording and reproduction.

Writing and reading information to and from an optical disc is usually performed by the following method.

Information is written by irradiating the optical disc with a laser beam, and the irradiated portion of the recording layer absorbs the light, causing a local temperature rise, causing physical or chemical changes (for example, bit generation). information is recorded by changing its optical properties. Information is also read by irradiating the optical disk with a laser beam, and the information is reproduced by detecting reflected or transmitted light depending on changes in the optical characteristics of the recording layer.

As described above, metals, dyes, and the like are known as recording materials forming the recording layer of such information recording media. Information recording media using dyes have advantages in the characteristics of the recording medium itself, such as higher sensitivity compared to recording materials such as metals, as well as manufacturing advantages in that the recording layer can be easily formed by a coating method. It has great advantages. However, recording layers made of dyes generally have low reflectance, it is difficult to obtain high C/N, and furthermore, characteristics such as recording sensitivity easily change depending on the oscillation wavelength of the laser beam used during recording or reproduction. There is.

Information is generally recorded using a dye as a recording layer by forming bits in the dye recording layer. As mentioned above, dyes have high sensitivity, but require relatively high recording power to form complete bits. That is, since a large recording power is required to obtain a recording signal with a high C/N, it is often not true that the sensitivity is high. Further, when a reflective layer is provided to improve the low reflectance, which is a drawback of the dye recording layer, there is a problem that it becomes even more difficult to form bits on the dye recording layer. Furthermore, compared to metal recording layers, dye recording layers are more likely to cause changes in recording characteristics such as recording sensitivity due to differences in the oscillation wavelength of the laser beam used during recording, and the oscillation wavelength is within a narrow wavelength range. It is difficult to record only with laser light.

For this reason, a dye recording layer that can use laser light of various wavelengths has not yet been obtained.

Therefore, the recording layer uses a dye that is advantageous in terms of productivity, has a high reflectance, a high recording signal C/N, and has recording characteristics that are not affected by differences in the oscillation wavelength of laser light. In other words, it is desirable to propose an information recording medium that is adaptable to lasers with various oscillation wavelengths.

[Object of the Invention] The present invention provides a method comprising a dye recording layer and a reflective layer on a substrate.
It is an object of the present invention to provide an information recording medium that has a high reflectance, a high C/N of a recorded signal, and whose recording characteristics are not easily affected by differences in the oscillation wavelength of laser light.

An object of the present invention is to provide an information recording method for recording a signal with a high C/N using a laser beam having an oscillation wavelength at an arbitrary wavelength in the range of 760 to 830 nm.

Another object of the present invention is to provide an information recording medium that can be played back on a commercially available CD player by recording a CD format signal using the optical information recording method described above.

[Summary of the Invention] The present invention provides the following general formula (1) on a disc-shaped substrate: [where RI, R2 and R3 are each an alkyl group, an aryl group or an alkenyl group which may have a substituent. groups, which may be the same or different, and X- represents an anion] The maximum light absorption as a pigment film and a cyanine dye having a naphthoindolenine skeleton represented by 750 to 900
An information recording medium comprising a dye recording layer comprising a dye having a wavelength range of nm, and a reflective layer comprising a metal on the recording layer in this order; and: While rotating the information recording medium, the substrate side An optical information recording method comprises recording information by irradiating the dye recording layer with a laser beam having an oscillation wavelength at an arbitrary wavelength within the range of 760 to 830 nm.

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

1) The dye having the absorption maximum in the wavelength range of 750 to 900 nm is a cyanine dye, a phthalocyanine dye,
Thiopyrylium/thiobim dyes, azulenium dyes, squarylium dyes, metal complex dyes such as Ni and Or, naphthoquinone/anthraquinone dyes, indophenol dyes, indoaniline dyes, triphenylmethane dyes, triallyl The above information recording medium is characterized in that it is at least one type of dye selected from methane dyes, aluminum/diimmonicum dyes, and nitroso compounds.

2) The above information recording medium, wherein the layer thickness of the dye recording layer is in the range of 500 to 2000X.

3) The above-mentioned information recording medium, wherein the material of the above-mentioned substrate is polycarbonate, polyolefin, or cell-cast polymethyl methacrylate.

4) The above metal is Au, Ag, Cu, Pt, Cr, Ti
, AJZ, and stainless steel.

5) The information recording medium, wherein the reflective layer has a thickness in the range of 500 to 2000X.

6) The information recording medium described above, further comprising a protective layer made of an ultraviolet curable resin provided on the reflective layer.

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

1) Recording of the above information is carried out by irradiating the dye recording layer with laser light from the substrate side at a constant linear velocity of 1.2 to 2.8 m/sec while rotating the information recording medium. The above optical information recording method.

2) The above-mentioned optical information recording, wherein the above-mentioned information recording is performed by irradiating a CD format signal with a laser beam from the substrate side to the dye recording layer at a constant linear velocity while rotating the information recording medium. Method.

[Effects of the Invention] As described above, the information recording medium of the present invention has a dye recording layer and a recording layer comprising a cyanine dye having a naphthoindolenine skeleton and a dye whose light absorption maximum as a dye film is on the longer wavelength side. A reflective layer is provided on the layer.

This has made it possible to significantly expand the oscillation wavelength range of the laser beam used during recording while maintaining the characteristics of cyanine dyes with naphthoindolenine skeletons, such as high recording sensitivity and high reflectance. .

In other words, the above-mentioned long-wavelength absorbing dye can widen the usable laser oscillation wavelength range by adding a small amount. without impairing its properties.

Therefore, the information recording medium of the present invention has high recording sensitivity and reflectance, and has a wide wavelength range (preferably 7
A laser having an arbitrary oscillation wavelength within the range of 60 to 830 nm can be used. In other words, it can be said that this is an information recording medium whose recording characteristics are less dependent on the oscillation wavelength of the laser beam.

Further, the information recording medium has an oscillation wavelength of 760 to 830n.
Any laser beam within the range of m can be advantageously used by the optical information recording method of the present invention, in which information is recorded by irradiating the information recording medium from the substrate side.

In particular, an information recording medium on which a CD format signal is recorded using the optical information recording method described above can be played back on a commercially available CD player.

[Detailed Description of the Invention] The information recording medium of the present invention has a basic configuration in which a dye recording layer and a reflective layer are provided in this order on a substrate.

The information recording medium of the present invention is a dye recording medium comprising a cyanine dye having a naphthoindolenine skeleton represented by the above-mentioned formula (1) and a dye having a maximum light absorption as a dye film in a wavelength range of 750 to 900 nm. A reflective layer is provided on the recording layer to increase the reflectance of the dye recording layer.

The above cyanine dye with naphthoindolenine skeleton is 60
It absorbs most of the light from around 0 nm to around 760 nm, and has the characteristics of low light absorption and high reflectance in the wavelength band around 800 nm, which is the oscillation wavelength of laser light used for recording and reproduction. For example, when a CD player is used to reproduce a CD format signal, the optical disc is required to have high reflectance and must be able to be reproduced using a laser beam with a wavelength of 780 nm. Therefore, in a recording layer consisting only of naphthoindolenine skeleton cyanine dyes,
When the above-mentioned laser beam is irradiated and reproduced on a CD player, since the recording layer has a high reflectance, the reproduction is performed satisfactorily. However, when recording information with a laser having the above wavelength, it cannot be said that information can be recorded with low recording power, and it cannot be said that the sensitivity is sufficiently high. That is, when the wavelength of the laser beam is 780 nm or less, it can be said that the sensitivity is relatively high, but when it exceeds 780 nm, the sensitivity tends to decrease. Even in the same optical recording device equipped with a laser whose oscillation wavelength is 780 nm, there are those whose laser light wavelength is less than 780 nm, and there are those whose wavelength exceeds 780 nm. Therefore,
Due to differences among these devices, their recording characteristics tend to change easily. When the oscillation wavelength is 800 nm or more, the recording sensitivity is further reduced.

Therefore, the inventors conducted further studies and found that by adding a dye whose maximum light absorption as a dye film is in the range of 750 to 900 nm (also called a long wavelength absorption dye) to the naphthoindolenine skeleton cyanine dye, It has become clear that the laser beam that can be used during recording can be applied to laser beams with a relatively wide range of oscillation wavelengths. Moreover,
The above-mentioned long-wavelength absorbing dyes can widen the usable laser oscillation wavelength range by adding a small amount, so they can improve the original characteristics of naphthoindolenine skeleton cyanine dyes, such as high reflectance and high recording sensitivity. It will not be damaged.

Therefore, the information recording medium of the present invention has high recording sensitivity and reflectance, and can use a laser with any oscillation wavelength in a wide wavelength range (preferably in the range of 760 to 830 nm) during recording or reproduction. be. In other words, it can be said that it is an information recording medium whose recording or reproducing characteristics are less dependent on the oscillation wavelength of the laser beam.

Further, the present invention can record information with a high C/N signal by irradiating the information recording medium from the substrate side with any laser beam having an oscillation wavelength in the range of 760 to 830 nm. .

In particular, since the information recording medium of the present invention has a high reflectance, it is preferable to hold the information recording medium at a distance of 1°2 to 2.8 m/
It can be advantageously used in the optical information recording method of the present invention in which a CD format signal is recorded by irradiating a laser beam from the substrate side while rotating at a constant linear speed of seconds.

The cyanine dye having a naphthoindolenine skeleton according to the present invention is a dye represented by the following general formula (1).

However, R1, R2 and R3 each represent an alkyl group, an aryl group or an alkenyl group which may have a substituent, and may be the same or different. Preferably, R1, R2 and R3 are lower alkyl groups, such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, and tert-butyl.

×- represents an anion, and is a -valent or divalent ion for supplying the number of negative charges necessary to neutralize the charge of the cation moiety.

Anions represented by ×- include Cu-Br-, I
-, CH30SO3-, paratoluenesulfonate ion, p-chlorobenzenesulfonate ion, methanesulfonate ion, butanesulfonate ion, naphthalene-1
, 5-disulfonate ion, perfluorosulfonate ion such as trifluoromethanesulfonate ion, PF
3-.

BF, -, CoO2-, etc., and preferred ones are trifluoromethanesulfonic acid ion, BF6- and C
X04-, and among these, trifluoromethanesulfonic acid ion and P Fa- are the most preferable since there is no risk of explosion.

Specific examples of the compound represented by the general formula (1) used in the present invention are listed below, but the scope of the present invention is not limited only to these.

a) b) C) The maximum absorption of light (λ, 1X) as a pigment film is 750 to 9
The dye having a wavelength range of 00 nm is not particularly limited, and any dye may be used. Preferably, the dye has a light absorption maximum in the range of 750 to 900 nm and has a large absorption coefficient. Such a dye having a large absorption coefficient is desirable because the amount added to the cyanine dye having a naphthoindolenine skeleton is small, so that the recording and reproducing properties of the cyanine dye having a naphthoindolenine skeleton are hardly impaired. . The amount of the dye having a light absorption maximum in the range of 750 to 900 nm added to the above cyanine dye having a naphthoindolenine skeleton is generally 0.1 to 10% per mole of the cyanine dye having a naphthoindolenine skeleton.
It is in the range of mol %, preferably in the range of 0.5 to 5 mol %. Examples of pigments include cyanine pigments, phthalocyanine pigments, thiopyrylium pigments and thiobim pigments,
Azulenium pigment, squalirium pigment, Ni, C
Examples include metal complex dyes such as r, naphthoquinone/anthraquinone dyes, indophenol dyes, indoaniline dyes, triphenylmethane dyes, triallylmethane dyes, aluminum/diimmonium dyes, and nitroso compounds. can. Preferable examples include cyanine dyes, azulenium dyes, and squarylium dyes.

The maximum absorption of light as the pigment film is 750 to 900 nm.
Specific examples of dyes having wavelengths in the wavelength range include the following.

d) λ, l1ax: 800ni+ e) λsaw near 80 nm f) λma, l near 73 nm The information recording medium of the present invention can be manufactured using, for example, the materials described below.

The substrate used in the present invention can be arbitrarily selected from various materials used as substrates for conventional information recording media. Optical properties, flatness, processability of the substrate,
In terms of ease of handling, stability over time, and manufacturing cost,
Examples of substrate materials include glass; acrylic resins such as cell cast polymethyl methacrylate and injection molded polymethyl methacrylate; vinyl chloride resins such as polyvinyl chloride and vinyl chloride copolymers; epoxy resins; polycarbonate resins, amorphous polyolefins, and Mention may be made of polyester. Preferably, mention may be made of polycarbonate, polyolefin and cell-cast polymethyl methacrylate.

The surface of the substrate on which the recording layer is provided has improved flatness,
An undercoat layer may be provided for the purpose of improving adhesive strength, improving the solvent resistance of the substrate, and preventing deterioration of the recording layer. Examples of materials for the undercoat layer include polymethyl methacrylate,
Acrylic acid/methacrylic acid copolymer, styrene/maleic anhydride copolymer, polyvinyl alcohol, N-methylolacrylamide, styrene/sulfonic acid copolymer,
Styrene/vinyltoluene copolymer, chlorosulfonated polyethylene, nitrocellulose, polyvinyl chloride, chlorinated polyolefin, polyester, polyimide, vinyl acetate/vinyl chloride copolymer, ethylene/vinyl acetate copolymer, polyethylene, polypropylene , polymeric substances such as polycarbonate; organic substances such as silane coupling agents; and inorganic oxides (S i 02 , A11g
03, etc.) and inorganic substances such as inorganic fluoride (MgFz).

The undercoat layer is formed by, for example, dissolving or dispersing the above substances in a suitable solvent to prepare a coating solution, and then applying this coating solution to the substrate surface using a coating method such as spin code, dip coating, or extrusion coating. can do. The layer thickness of the undercoat layer is generally o, oos ~ 20
It is in the range of μm, 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 undercoat layer) for the purpose of forming tracking grooves or unevenness representing information such as address signals. The material for the pre-groove layer etc. is at least one monomer selected from monoesters, diesters, triesters and tetraesters of acrylic acid (
or oligomer) and a photopolymerization initiator can be used.

The formation of the pre-groove layer begins with the F# densely formed matrix (
After applying the above-mentioned mixture of acrylic ester and polymerization initiator onto a stand bar, and placing a substrate on top of this coating layer, the liquid layer is cured by irradiation with ultraviolet rays through the substrate or matrix. to fix the substrate and the liquid phase. Next, by peeling the substrate from the mother mold, a substrate provided with a pregroove layer is obtained. The thickness of the pregroove layer is generally 0.05 to 100! , in the range of tm,
Preferably it is in the range of 0.1 to 50 μm. When the substrate material is plastic as in the present invention, pregrooves and/or prepits may be directly provided on the substrate by injection molding, extrusion molding, or the like.

A recording layer made of the dye of the present invention described above is provided on the substrate (or pregroove layer, etc.).

Note that various antioxidants and singlet oxygen quenchers may be added to the mixture of these dyes to improve durability.

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

Examples of the solvent for preparing the dye coating solution include esters such as ethyl acetate, 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, alcohols such as ethanol, n-propatol, isopropatol, and lobetanol, amides such as dimethylformamide, fluorinated solvents such as 2.2.3.3-tetrafluoropropatol, etc. can be mentioned. Note that these non-hydrocarbon organic solvents may contain hydrocarbon solvents such as aliphatic hydrocarbon solvents, alicyclic hydrocarbon solvents, and aromatic hydrocarbon solvents, as long as the amount is within 50% by volume. .

The coating solution also contains antioxidants, UV absorbers, plasticizers,
Various additives such as lubricants may be added depending on the purpose.

When a binder is used, examples of the binder include cellulose derivatives such as gelatin, nitrocellulose, and cellulose acetate; natural organic polymeric substances such as dextran, rosin, and rubber; and carbonized materials such as polyethylene, polypropylene, polystyrene, and polyisobutylene. Hydrogen resins, vinyl resins such as polyvinyl chloride, polyvinylidene chloride, polyvinyl chloride/polyvinyl acetate copolymers, acrylic resins such as polymethyl acrylate, polymethyl methacrylate,
Examples include synthetic organic polymeric substances such as polyvinyl alcohol, chlorinated polyolefins, epoxy resins, butyral resins, rubber derivatives, and initial condensates of thermosetting resins such as phenol/formaldehyde resins.

Examples of the coating method include a spray method, a spin code method, a dip method, a roll coat method, a blade coat 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 dye to binder is generally 0.01 to 99% (weight ratio).
It is 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 1.
It is in the range of 00 to ioooo, preferably 500
It is in the range of ~2000 or more. Furthermore, the recording layer may be provided not only on one side of the substrate but also on both sides.

A protective layer may be provided on the dye recording layer of the present invention for the purpose of physically and chemically protecting the recording layer and the entire information recording medium. Further, this protective layer may be provided on the side of the substrate where the recording layer is not provided for the purpose of increasing scratch resistance and moisture resistance.

Examples of materials used for the protective layer include inorganic materials such as SiO, 5i02, Si3N4, MgF, 5n0
2nd place can be mentioned. In addition, as organic substances,
Examples include thermoplastic resins, thermosetting resins, UV curable resins, etc., with UV curable resins being preferred.

The protective layer can be formed, for example, by laminating a film obtained by plastic extrusion onto the dye recording layer via an adhesive layer. Alternatively, it may be provided by methods such as vacuum deposition, sputtering, and coating. In addition, in the case of thermoplastic resins and thermosetting resins,
After preparing a coating solution by dissolving these in an appropriate solvent,
It can also be formed by applying this coating liquid and drying it. In the case of a UV curable resin, it can also be formed by preparing a coating liquid as it is or by dissolving it in an appropriate solvent, applying this coating liquid, and curing it by irradiating it with UV light. Examples of UV curable resins include urethane (meth)acrylate, epoxy (meth)acrylate, polyester (meth)acrylate,
Oligomers of meth)acrylates, polymers such as (meth)acrylic acid esters, and ordinary UV-curable resins such as photopolymerization initiators can be used. Various additives such as antistatic agents, antioxidants, and UV absorbers may be further added to these coating liquids depending on the purpose.

The thickness of the protective layer is generally in the range of 0.1 to 1100 At.

On top of the dye recording layer, there is a S/N ratio at the time of information reproduction.
A reflective layer is provided for the purpose of improving the recording speed and sensitivity during recording.

The light-reflective substance that is the material of the reflective layer is a substance that has a high reflectance to laser light, and examples thereof include Mg%Se.
, Y, Ti, Zr, Hf%V.

Nb, Ta, Cr, Mo, W, Mn, Re.

Fe% Co% Ni, Ru, Rh, Pd, Ir.

Pt, Cu, Ag%Au, ZnS Cd%Aj! , Ga
, In, Si, Ge, Te, Pb, Po, Sn, Bi, and other metals and metalloids. Among these, preferred are Au, Al1. These are Cr and Ni. These substances may be used alone, or in combination of two or more or as an alloy.

The reflective layer can be formed on the recording layer by, for example, vapor deposition, sputtering, or ion-blating the above-mentioned light-reflective material.

The thickness of the reflective layer is generally in the range of 100 to 3000X,
Preferably it is 500-2000λ.

In the present invention, the information recording medium may be a single substrate having the above-mentioned structure, or may further include two substrates having the above-mentioned structure facing each other so that the recording layer is on the inside,
A bonded type recording medium can also be manufactured by bonding using an adhesive or the like. Alternatively, an air sandwich type recording medium is manufactured by using a substrate having the above configuration as at least one of two disc-shaped substrates and joining them via a ring-shaped inner spacer and a ring-shaped outer spacer. You can also.

Next, the method for recording information on the information recording medium of the present invention is as follows:
Since this is useful for recording format signals, this will be explained using this as an example.

First, while rotating the information recording medium at a constant linear velocity within the range of 1.2 to 2.8 m/sec, recording light such as semiconductor laser light is irradiated from the substrate side. Generally, a semiconductor laser beam having an oscillation wavelength in the range of 770 to 830 nm is used as the recording light. In addition, in the present invention, recording can be performed with an irradiation power of 10 mW or less,
High sensitivity.

As a result, bits having a length of 0.84 to 3.6 μm are formed concentrically or spirally at intervals of 0.84 to 3.6 μm in the recording layer. EFM signal information such as a CD format signal is then written to the recording layer.

Signals may be recorded either on the grooves or between the grooves. At this time, recording for 60 minutes or more is possible with a recording medium whose signal surface has an inner diameter of 50 mm and an outer diameter of 115 mm.

Incidentally, during recording, it is preferable to perform tracking control using a tracking groove.

Information can be reproduced by rotating the recording medium at the same constant linear velocity as described above, irradiating semiconductor laser light from the substrate side, and detecting the reflected light. In the present invention, since the recording layer has a high reflectance of 60% or more on a plain plane, it can be read satisfactorily using a commercially available CD player.

Note that the information recording medium of the present invention includes a CD-ROM, a CD-ROM, and a CD-ROM.
It is essentially compatible with media recorded in CD format such as 1.

Next, Examples and Comparative Examples of the present invention will be described.

However, each of these aspects does not limit the invention.

Examples and comparative examples of the present invention will be described below in the margins. However, each of these aspects does not limit the invention.

[Example 1] The above dye example a) The above dye example d) The above dye a) and 1 mol % of dye b) with respect to dye a)
A dye recording layer coating solution was prepared by dissolving 2.75 g of a mixed dye consisting of the following in 100 cc of 2°2.3.3-tetrafluoropropanol.

A disc-shaped polycarbonate substrate with a tracking guide (outer diameter: 120 mm, inner diameter: 15 mm, thickness:
1.2mm, track width = 1゜0μm = track pitch = 1.6μm, group depth 2800λ), the above coating solution was applied by spin code method at a rotation speed of 1000 rpm.
After coating at a speed of 1,300 mm, it was dried to form a recording layer having a thickness of 1,300 mm.

On the recording layer, Au was deposited to form a reflective layer having a thickness of 1300×.

Next, on the reflective layer, an ultraviolet curable resin (trade name + 3
070 (manufactured by ThreeBond) was applied and irradiated with ultraviolet rays using a high-pressure mercury lamp to form a protective layer with a layer thickness of 2 μm.

In this way, an information recording medium consisting of a substrate, a dye recording layer, a reflective layer and a protective layer was manufactured.

[Comparative Example 1] An information recording medium was produced in the same manner as in Example 1, except that the dye recording layer was formed only with the dye a) without adding the dye d).

[Evaluation of Information Recording Media] The recording power was varied on the information recording media obtained in Example 1 and Comparative Example 1 above using a recording evaluation machine (manufactured by Pulstic Co., Ltd.) and a function generator (manufactured by Kikusui Denshi ■). A reference signal (0.72 M) Iz) was recorded at a constant linear velocity of 1.3 m/sec. As lasers for recording, optical pickups with excavation wavelengths of 780 nm and 790 nm were prepared and used interchangeably. And C when playing
The recording power at which /N became 50 dB or more was defined as the recording sensitivity.

The above results are shown in Table 1.

Furthermore, the signal from the EFM encoder (manufactured by Kenwood ■) was recorded under the above recording conditions, and the recorded information was played back using a commercially available CD player (337ESD, manufactured by Sony ■) at a power of 0.18 mW. Example 1
Both the optical disc of Comparative Example 1 and the optical disc of Comparative Example 1 were playable.

7gf Table 780 nm laser 790 nm laser recording sensitivity (mW) Recording sensitivity (mW) Example 1
6. 5 6. 5 Comparative Example 1 6.5
8.0 As can be seen from Table 1, the naphthoindolenine skeleton cyanine dye (a) of the present invention has 75
In the case of Example 1 according to the present invention in which a dye in the range of 0 to 900 nm is added, the applicable range of laser wavelength is wide, and
Recording can be performed with the same recording power with either an 80 nm laser or a 790 nm laser.

On the other hand, cyanine dye with naphthoindolenine skeleton (a))
In the case of Comparative Example 1, the applicable range of the laser wavelength was narrow, and when recording with a 790 nm laser, the recording sensitivity decreased.

Therefore, it can be seen that the information recording medium of the present invention not only has excellent recording and reproducing characteristics, but also has a wide applicable range of usable laser wavelengths.

Claims (1)

[Claims] 1. On the disc-shaped substrate, the following general formula (1); ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (1) [However, R^1, R^2 and R^3 are , each represents an alkyl group, an aryl group, or an alkenyl group which may have a substituent, and may be the same or different from each other, and X^- represents an anion] A naphthoindolenine skeleton represented by The maximum light absorption as a cyanine dye and a pigment film is 750 to 900.
An information recording medium comprising: a dye recording layer made of a dye having a wavelength range of nm; and a reflective layer made of metal provided on the recording layer in this order. 2. On the disc-shaped substrate, the following general formula (1); ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (1) [However, R^1, R^2 and R^3 each have a substituent. represents an alkyl group, aryl group or alkenyl group which may be the same or different, and X^- represents an anion. The maximum light absorption as a pigment film is 750 to 900.
A dye recording layer made of a dye having a wavelength range of nm, and a reflective layer made of a metal on the recording layer are provided in this order. While rotating the information recording medium, the dye recording layer is coated from the substrate side with a 760-degree angle. An optical information recording method comprising recording information by irradiating a laser beam having an oscillation wavelength at an arbitrary wavelength within the range of ~830 nm.