JPH04175188A - Information recording medium and optical information recording method - Google Patents

Abstract

PURPOSE:To obtain an information recording medium remarkably improved in C/N ratio, reflectance, and sensitivity by a method wherein a recording layer containing a cyanine dye having a specific benzoindolenine skeleton is provided on a substrate, and thereon a reflecting layer made of a metal is provided. CONSTITUTION:On a substrate, a recording layer containing a cyanine die having a benzoindolenine skeleton is provided. On the recording layer, information can be recorded by laser. Said benzoindolenine skeleton is shown by a formula I [in the formula, R<1>, R<2>, and R<3> respresent alkyl group which may independently have substituent; Y represents methyl group, ethyl group, or benzyl group; X<n-> is anion; (n) is 1, 2, or 3; and R<2> and R<3> may link with each other to form a ring]. Furthermore, a reflecting layer made of a metal is provided on said recording layer. In this manner, an information recording medium is produced. For forming the recording layer, the dye shown by the formula I is dissolved in a solvent together with a quencher, a binder, and the like, as required, to prepare a coating liquid, the coating liquid is applied on the surface of the substrate to form a film, and the film is dried.

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 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.

D RA W (Direct Read After
The basic structure of a write-type optical disk is a disc-shaped substrate made of glass, synthetic resin, etc., and a metal or metalloid such as Bi, Sn, In, Te, etc.; or a cyanine-based or metal complex system provided on this. , and a recording layer made of a quinone-based dye. Note that an intermediate layer made of a polymeric substance is 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. There are cases.

Information is written on an optical disc 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 and causing physical or chemical changes (for example, pits). 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 characteristic problems such as low reflectance and low C/N of reproduced signals, and drawbacks such as the dye recording layer easily deteriorating over time due to light irradiation. are doing.

As a recording layer made of a dye with improved reflectance and C/N, JP-A-64-40382 discloses a recording layer made of a cyanine dye having a benzindolenine skeleton (a structure in which a benzene ring is fused to an indolenine skeleton). An optical disc having layers is disclosed. Among the cyanine dyes having a benzindolenine skeleton, the above publication discloses a dicarbocyanine dye in which the methine chain connecting two benzindolenine skeletons is composed of five unsubstituted methine groups. . However, according to studies by the present inventors, an information recording medium having such a dye recording layer is
Although the C/N is relatively good, the reflectance,
Furthermore, the light resistance is not satisfactory.

In order to increase the reflectance, it is common practice to further provide a reflective layer on the dye recording layer. An example of this is described in Nikkei Electronics (page I07, published January 23, 1989), which states that although the dye used in the recording layer of the recording medium is unknown, the recording method is unknown. However, it is disclosed that the dye is melted by laser absorption in the dye recording layer, and the plastic substrate is heated accordingly, and the substrate bulges toward the recording layer side, forming bits. is being done. This reflective layer is a vapor-deposited gold film. Furthermore, EPC Patent Publication No. 0353393 discloses the use of a cyanine dye having the above-mentioned benzindolenine skeleton in the dye recording layer of this optical disc with a reflective layer. This results in
An optical disc having a relatively high C/N and improved reflectance can be obtained.

Even with DRAW type optical discs, in high-density recording of CD format signals (CD-DRAW), the constant linear velocity is 1.2 to 1.
．． It is necessary to record the above-mentioned signals at a slow speed of 4 m/sec, and it is required that the recorded signals be played back on a commercially available CD player. For playback on a CD player, it is desirable that the optical disc has a reflectance of at least 70%. However, according to studies conducted by the present inventors, even if a CD format signal is recorded on an optical disc having a recording layer of cyanine dye having a benzindolenine skeleton and a reflective layer, some CD players may not be able to reproduce the signal. Ta. Furthermore, in order to improve the light resistance of the recording layer, diimmonium, aminium, or metal complex dyes may be added to the above dyes, and the reflectance of the recording layer in this case generally tends to decrease. It turned out that it is difficult to obtain both high reflectance and excellent light resistance.

Therefore, it is desired for the above-mentioned CD-DRAW to have an optical tiff with excellent recording and reproducing characteristics and a significantly high reflectance (approximately 80%).

[Object of the Invention] An object of the present invention is to provide an information recording medium having a recording layer and a reflective layer thereon, which has significantly improved C/N and reflectance.

Another object of the present invention is to provide an information recording medium having a recording layer and a reflective layer thereon, in which the C/N and reflectance are significantly improved and the light resistance is excellent. .

A further object of the present invention is to provide an information recording medium having a recording layer and a reflective layer thereon, which has significantly improved C/N, reflectance, and sensitivity.

[Summary of the Invention] The present invention provides the following general formula (■);
l, R2 and R3 each independently represent an alkyl group which may have a substituent, Y represents a methyl group, ethyl group or benzyl group, Xn- represents an anion, and n is 1.2 or 3, and R2 and R
3 may be connected to each other to form a ring. ] An information recording medium comprising: a laser containing a cyanine dye having a benzoindolenine skeleton represented by '; a recording layer capable of recording information; and a reflective layer made of metal provided on the recording layer. It is in.

Furthermore, while rotating the information recording medium, the oscillation wavelength is 750 to 85, and the oscillation wavelength is 750 to 85.
It can be advantageously used in an optical information recording method that involves recording information by irradiating a laser within a range of 0 nm.

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

1) The above-mentioned information recording medium, characterized in that R1 of the above general formula (I) is R1 or an alkyl group having 1 to 4 carbon atoms which may have a substituent.

2) The information recording medium described above, wherein R2 and R3 in the general formula (I) are each an unsubstituted alkyl group having 1 to 4 carbon atoms.

3) xo- in the above general formula (I) is a halogen ion, a sulfonate ion, Cft0. -1BF, -1SbF6
-1 metal complex ion or phosphate ion.

4) The above-mentioned information recording medium, in which a pre-groove is formed on the above-mentioned substrate.

5) The information recording medium according to 4) above, wherein the depth of the break loop is in the range of 300 to 2000λ and the half width thereof is in the range of 0.2 to 0.9 μm.

6) The information recording medium according to 4) above, wherein the depth of the pregroove is in the range of 1500 to 2000λ and the half width thereof is in the range of 0.2 to 0.9 μm.

7) The information recording medium described above, wherein the material of the substrate is plastic.

8) The above metal is Cr, Ni, Pt, Cu, Ag, Au,
A1. and stainless steel.

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

1) The optical information recording method described above, wherein the medium is rotated at a constant linear velocity of 1.2 to 1.4 m/sec.

2) The optical information recording method described above, wherein the information is an EFM signal in CD format.

[Effects of the Invention] A recording layer made of a specific cyanine dye having a benzindolenine skeleton represented by the above general formula (I) is provided on a substrate, and a reflective layer made of metal is further laminated on the recording layer. The optical disc of the present invention not only has superior recording and reproducing characteristics such as C/N and modulation degree, but also has a significantly high reflectance.

Furthermore, since the optical disc of the present invention has a significantly high reflectance, it is possible to maintain a high level of reflectance even if a quencher or the like that tends to reduce the reflectance of the recording layer is added to improve light resistance. can. Therefore, an optical disc having excellent light resistance and high reflectance can be obtained.

In addition, especially when the dye layer of the present invention and the reflective layer are provided on the substrate having a deep pregroove of 1,500 to 2,000 λ as described above, the sensitivity can be improved without substantially reducing the reflectance. I can do it.

Furthermore, since the resulting optical disc has a significantly high reflectance, it is possible to record a CD-format EFM signal on a commercially available CD.
Since it can be played on a player, CD-DRAW
It is useful as

[Detailed Description of the Invention] The information recording medium of the present invention has the above general formula (I) on a substrate.
It has a basic structure in which a recording layer containing a cyanine dye having a benzoindolenine skeleton represented by is provided, and a reflective layer is provided on the recording layer.

The present inventors have discovered that a dye that can be used in the recording layer of the optical disc with the reflective layer material allows the resulting optical disc to have a high C//
We have been conducting extensive research in search of new dyes, such as N, that exhibit pleasant recording and reproducing properties and high reflectance. As a result, it has been found that this can be achieved by using a cyanine dye having a benzindolenine skeleton represented by the above general formula (I) as a recording layer.

That is, the cyanine dye of the present invention represented by the above general formula (I) can change its absorption maximum to the short wavelength side or to the long wavelength side by changing its structure. It has become clear that most of these exhibit characteristics of high reflectivity in the wavelength band around 780 nm, which is the oscillation wavelength of general laser light, and also high C/N and modulation.

The information recording medium of the present invention can be manufactured, for example, by the method described below.

The substrate of the present invention can be arbitrarily selected from various materials used as substrates of conventional information recording media. As the substrate material of the present invention, for example, glass; polycarbonate: acrylic resin such as polymethyl methacrylate;
Examples include vinyl chloride resins such as polyvinyl chloride and vinyl chloride copolymers; epoxy resins; Amorph Z polyolefins and polyesters; these may be used in combination if desired. Note that these materials can be used in the form of a film or as a rigid substrate. Among the above materials, polycarbonate is preferred in terms of moisture resistance, dimensional stability, cost, and the like.

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 and preventing deterioration of the recording layer. Examples of materials for the undercoat layer include polymethyl methacrylate, acrylic acid/methacrylic acid copolymer, styrene/maleinate anhydride copolymer, polyvinyl alcohol, N-methylolacrylamide, styrene/vinyltoluene copolymer, and chlorosulfonated polyethylene. , nitrocellulose, polyvinyl chloride, chlorinated polyolefin, polyester, polyimide, vinyl acetate/vinyl chloride copolymer, ethylene/vinyl acetate copolymer, polyethylene, polypropylene, polycarbonate, and other polymeric substances; and silane coupling agents, etc. organic substances can be mentioned.

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 0.005 to 20
It is in the range of μm, preferably in the range of 0.01 to 10 μm.

Further, it is preferable that the substrate (or the undercoat layer) has grooves for tracking or irregularities representing information such as an address signal. When a resin material such as polycarbonate is used, it is preferable that the resin material is formed into groups directly on the substrate by injection molding or extrusion molding.

Further, the group formation may be performed by providing a pre-groove layer. The material for the pre-groove layer is at least one of acrylic acid monoesters, diesters, triesters and tetraesters.
(or oligomer) and a photoinitiator can be used.

The pre-groove layer is formed by first coating a mixture of the above acrylic ester and polymerization initiator on a precisely made matrix (stamper), then placing the substrate on top of this coating solution layer. Then, the liquid layer is cured by irradiation with ultraviolet rays through the substrate or the matrix, thereby fixing 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 in the range of 0.05 to 100 μm, preferably in the range of 0.1 to 50 μm.

In the present invention, the depth of the pregroove provided on the substrate is in the range of 300 to 2000λ, and the half width thereof is in the range of 0.2 to 0.
．． A range of 9 μm is preferred. Further, by setting the depth of the pregroove in the range of 1500 to 2000X, sensitivity can be improved without substantially reducing the reflectance, which is particularly preferable. Therefore, such an optical disc (
A recording layer and a reflective layer of the dye of general formula (I) are formed on a deep pregroove substrate), which has high sensitivity and enables recording even with low laser power, which makes it possible to use inexpensive semiconductor lasers. It has advantages such as making it possible to perform the following steps, and extending the service life of the semiconductor laser.

A recording layer of the present invention is provided on the substrate.

The recording layer of the present invention is characterized by containing a cyanine dye having a benzindolenine skeleton represented by the following general formula (I).

[In the formula, RI, R2 and R3 each independently represent an alkyl group which may have a substituent, Y represents a methyl group, ethyl group or benzyl group, Xo- represents an anion, and n represents 1.2 or 3, and R2 and R3 may be linked to each other to form a ring. ] The alkyl group represented by R1 in the above-general (I) preferably has 1 to 1 carbon atoms, which may be substituted.
4 alkyl group, more preferably an unsubstituted alkyl group having 1 to 4 carbon atoms, and most preferably a methyl group.

Substituents for the alkyl group represented by R1 in formula (I) above include halogen atoms such as F and Cfl; alkoxy groups such as methoxy and ethoxy groups; alkylthio groups such as methylthio group and ethylthio group; niacetyl group; Acyloxy groups such as acetoxy groups; hydroxy groups; alkoxysulfonyl groups such as ethoxycarbonyl groups; alkenyl groups such as vinyl groups; and aryl groups such as phenyl groups. Preferred examples of the above substituents include halogen atoms such as F and Cfi; alkoxy groups such as methoxy and ethoxy; and alkylthio groups such as methylthio and ethylthio.

The alkyl groups represented by R2 and R3 in formula (I) above are each an optionally substituted alkyl group having 1 to 4 carbon atoms, and R2 and R3 are connected to each other to form a ring. R2 and R3 may be connected to each other to form a ring, and are preferably an unsubstituted alkyl group having 1 to 4 carbon atoms, and more preferably a methyl group or an ethyl group.

As substituents for the alkyl group represented by R2 and R3 in the above-mentioned formula (I), halogen atoms such as F and CA:
Alkoxy groups such as methoxy groups and ethoxy groups: alkylthio groups such as methylthio groups and ethylthio groups; acyl groups such as niacetyl groups; acyloxy groups such as acetoxy groups;
Examples include hydroxy groups; alkoxycarbonyl groups such as ethoxycarbonyl groups; alkenyl groups such as vinyl groups; and aryl groups such as phenyl groups.

The group represented by Y in formula (I) above is preferably a methyl group or a pencil group, particularly preferably a methyl group.

In addition, preferred anions represented by xo- include halide ions (e.g., Cl3-, Br-1-)
, sulfonate ions (e.g., CH3SbF6-1) metal complex ions (e.g., and and phosphate ions (e.g., PF5-1).

Among these, the particularly preferred X anion is CIO4
-1P F s- and i.

In addition, the anion represented by xo- is R1, R2, R
As a substituent for 3 or Y, it may exist in the form of an anion such as a sulfonate group to form an inner salt.

The optical disc of the present invention has a recording layer formed on a substrate using a specific cyanine dye having a benzindolenine skeleton represented by formula (I) above, and a reflective layer further provided on the recording layer. It shows the reflectance as well as the recording sensitivity, C/
It also exhibits excellent recording and reproducing characteristics such as N. The recording layer of the cyanine-based dye having a benzoindolenine skeleton generally has a maximum absorption wavelength on the shorter wavelength side than around 710 nm, and is light in the wavelength band around 780 nm, which is the oscillation wavelength of the laser beam used for recording or reproduction. Its absorption is relatively small, and when a reflective layer is provided on the recording layer, the reflectance of the resulting optical disc is significantly improved. That is, since light absorption is relatively small and the transmittance is high in the wavelength band around 780 nm, most of the light transmitted through the recording layer is reflected by the reflective layer, so it is estimated that the reflectance of the optical disc is improved.

Specific examples of compounds represented by the above formulas include I-1 to I-24 below.

The following margins Knee 4 Knee 6 Knee 7 CIO Knee 9 CIO, - l-10 ■-11 C2H3C104-C2H5 n -C3H, n -C3H7 C10 19 ■-21 Ni 22 ■-23 Ni 24 The cyanine dye having a benzindolenine skeleton represented by the general formula (I) of the present invention is disclosed in JP-A No. 64-40382.
It is included in the general formula of dyes used in the recording layer of optical discs described in JP-A-64-40387 and JP-A-64-40387.

For general synthesis methods and chemical behavior of the above dyes, please refer to r.
Chemistry of Heterocyclic Compounds J (The Chemist
ryof Heterocyclic Compound
d) Series r cyanine dyes and related compounds J
(Cyanine Dyes and Related
Compound, John Wiley & 5o
ns, New York, London; 1964
published).

Since the above-mentioned literature does not disclose a synthesis method for a preferred cyanine dye represented by the general formula (I) of the present invention, an example will be given below to explain it.

Synthesis Example 1 (Synthesis of Dye I-1) 150 ml of pyridine was added to 40 g of 1.2.3.3-tetramethylbenzo[e]-3H-indolium p-toluenesulfonate, and 1.1, 3. 37 g of 3-tetraethoxy-2-methylpropane was added dropwise. Thereafter, after heating under reflux for 1 hour, the solvent was distilled off under reduced pressure, and 500 ml of methanol was added to the residue. After filtering out insoluble matter, 20 ml of a 60% aqueous perchloric acid solution was added while stirring under water cooling. The resulting crystals were collected by filtration to obtain 30 g of crude crystals of dye 1-1. After dissolving this in chloroform, it was diluted with methanol, and the chloroform and methanol were further distilled off to obtain crystals of dye I-1.

Yield +25.5g Melting point: 187-189°C Synthesis example 2 (synthesis of dye I-2) In synthesis example 1, 1,1,3.3-tetraethoxy-
Synthesis Example 1 except that 1.1°3.3-tetraethoxy-2-benzylpropane was used instead of 2-methylpropane.
Dye 1-2 was obtained in the same manner as above.

Melting point: 246-248°C Synthesis Example 3 (Synthesis of Dye I-7) In Synthesis Example 1, 1-ethyl was used instead of 1,2,3,3-tetramethylbenzo[e]-38-indolium p-toluenesulfonate. Dye I-7 was obtained in the same manner as in Synthesis Example 1, except that -2°3.3-trimethylbenzo[e] -3H-indolium paratoluenesulfonate was used.

Melting point: 221-233°C Synthesis Example 4 (Synthesis of Dye I-8) In Synthesis Example 1, 1-propyl was used instead of 1,2,3,3-tetramethylbenzo[e]-38-indolium p-toluenesulfonate. Dye 1-8 in the same manner as in Synthesis Example 1 except that -2゜3.3-trimethylbenzo[e]-3H-indolium paratoluenesulfonate was used.
I got it.

Melting point: 230-234°C Synthesis Example 5 (Synthesis of Dye I-9) In Synthesis Example 1, 1-butyl was used instead of 1,2,3,3-tetramethylbenzo[e]-38-indolium p-toluenesulfonate. -2゜Dye 1 was prepared in the same manner as in Synthesis Example 1, except that 3.3-trimethylbenzo[eco-3H-indolium iodide was used, a small amount of ethanol was added in addition to pyridine as a solvent, and the mixture was heated to reflux. -9
I got it.

Melting point: 198-199°C To form the recording layer, various dyes known as so-called singlet oxygen quenchers are used together with the dye of the present invention to improve light resistance, such as the following general formula (n),
It is preferable to use a compound represented by (III) or (TV) in combination.

(However, [Catlも represents a nonmetallic cation such as tetraalkylammonium, M represents a transition metal atom such as Ni, 2 and Z' are an optionally substituted benzene ring, 2-thioctu-1゜Represents an atomic group for completing a 5- to 6-membered aromatic ring such as a 3-dithiol ring or a petro ring) 2Q-・ ・ ・ ・ ・ (m) [In the formula, R has a substituent, Q represents the same anion as that shown by X in general formula (I)] [wherein R represents the same group as in general formula (m), Q represents the same ) represents an anion synonymous with the above general formula (I
Quencher represented by I), (m) or (IV)
Specific examples include PA-1006 (Mitsui Toatsu Fine ■), IRQ-023, IRQ-022, and IRG-
Examples include Nippon Kayaku 003 (hereinafter referred to as Nippon Kayaku ■).

The amount of the quencher added is preferably 5 to 30 parts by weight per 100 parts by weight of the dye of formula (I).

To form the recording layer, a coating solution is prepared by dissolving the above-mentioned dye and, if desired, the above-mentioned Quencher 1 binder, etc. in a solvent, and this coating solution is then applied to the surface of the substrate to form a coating film, which is then dried. This can be done by

Solvents for preparing the dye layer coating solution of the present invention include esters such as ethyl acetate, butyl acetate, and cellosolve acetate; ketones such as methyl ethyl ketone, cyclohexanone, and methyl isobutyl ketone; dichloromethane, 1.2-
Chlorinated hydrocarbons such as dichloroethane and chloroform;
Amides such as dimethylformamide; hydrocarbons such as cyclohexane; tetrahydrofuran, ethyl ether,
Ethers such as dioxane; Alcohols such as ethanol, n-propertool, isopropertool, n-butanol diacetone alcohol; Fluorine solvents such as 2゜2.3.3-tetrafluoropropertool; ethylene glycol monomethyl ether, ethylene Examples include glycol ethers such as glycol monoethyl ether and propylene glycol monomethyl ether. The above solvents can be used alone or in combination of two or more, as appropriate, taking into consideration the solubility of the dye used.

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 natural organic polymer substances such as gelatin, cellulose derivatives, dextran, rosin, and rubber; hydrocarbon resins such as polyethylene, polypropylene, polystyrene, and polyisobutylene, and polyvinyl chloride. , vinyl resins such as polyvinylidene chloride, polyvinyl chloride/polyvinyl acetate copolymers, acrylic resins such as polymethyl acrylate and polymethyl methacrylate, polyvinyl alcohol, chlorinated polyethylene, epoxy resins, butyral resins, rubber derivatives ,
Examples include synthetic organic polymeric substances such as initial condensates of thermosetting resins such as phenol-formaldehyde resins.

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 concentration of the coating liquid thus prepared is generally in the range of 0.01 to 10% (by weight), preferably in the range of 0.1 to 5% (by weight).

The recording layer may be a single layer or a multilayer, but the layer thickness is generally 2.
in the range of 00 to 3000λ, preferably 500 to 2
It is in the range of 500λ. Furthermore, the recording layer may be provided not only on one side of the substrate but also on both sides.

Examples of the coating method include a spray method, a spin code method, a dip method, a roll coat method, a plate coat method, a doctor roll method, and a screen printing method.

Furthermore, the information recording medium of the present invention includes, on the recording layer,
A reflective layer is provided for the purpose of improving reflectance during information reproduction.

The light-reflective material that is the material of the reflective layer is a material that has a high reflectance to laser light; examples thereof include Mg, Se,
, Y, Ti, Zr, Hf, ■, Nb, Ta, Cr, Mo
, W, Mn, Re.

Fe, Co, Ni, Ru, Rh, Pd, Ir, Pt, C
u, Ag, Au, 2n, Cd%AIl, Ga, In, S
Examples include metals and semimetals such as i, Ge, Te, Pb, Po, Sn, and Bi, and stainless steel. Among these, preferred are Cr, Ni, Pt,
'Cu, Ag, Au, ALL and stainless steel. 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 3000 mm.

Furthermore, a protective layer may be provided on the reflective layer for the purpose of physically and chemically protecting the recording layer and the like. This protective layer may also 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 5iO1Si0
2. Inorganic substances such as MgF2, SnO□, and Si3N4: Examples include organic substances such as thermoplastic resins, thermosetting resins, and UV curable resins.

The protective layer can be formed, for example, by laminating a film obtained by plastic extrusion with an adhesive layer on the reflective layer and/or on the substrate. Alternatively, it may be provided by methods such as vacuum deposition, sputtering, and coating. In the case of a thermoplastic resin or a thermosetting resin, it can also be formed by dissolving these in a suitable solvent to prepare a coating solution, then applying this coating solution and drying it. In the case of 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 this coating solution, and curing it by irradiating it with UV light. . 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 100 μm.

In the present invention, the information recording medium may be a single board having the above-mentioned structure, or alternatively, two substrates having the above-mentioned structure may be placed facing each other so that the recording layer is on the inside, and adhesive or the like is used. By joining, a laminated type recording medium can also be manufactured. 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.

The information recording medium of the present invention can be manufactured by the method described above.

The optical disk thus obtained, which has an extremely high reflectance and excellent recording and reproducing properties, can maintain a desired reflectance even when a single peak quencher is added to improve light resistance. That is, when the above-mentioned quencher is added, the reflectance of the optical disc generally decreases, but since the information recording medium of the present invention has a significantly high reflectance of around 80%, even if the quencher is added, It can maintain high reflectance and can be played on commercially available CD players. Therefore, an optical disc having high reflectance and excellent light resistance can also be obtained.

The optical information recording method of the present invention is carried out, for example, as follows using the information recording medium.

First, while rotating the information recording medium at a constant linear velocity (1.2 to 1.4 m/sec in the case of CD format) or constant angular velocity, recording light such as semiconductor laser light is irradiated from the substrate side. By irradiating this light, a cavity is formed at the interface between the recording layer and the reflective layer (the cavity is formed by deforming the recording layer or the reflective layer, or by deforming both layers).
Alternatively, it is considered that information is recorded when the refractive index changes due to build-up deformation of the substrate, discoloration of the recording layer, change in association state, etc. 750 as recording light
A semiconductor laser beam having an oscillation wavelength in the range from nm to 850 nm is used.

The information recorded as above can be reproduced by rotating the information recording medium at the same constant linear velocity as above, irradiating semiconductor laser light from the substrate side, and detecting the reflected light. .

Examples of the present invention are described below. However, the sides of the stiffness do not limit the invention.

Margin below [Example 1] 2.0 g of the cyanine dye represented by formula (I) (above dye 1-1) was mixed with 2.2,3°3-tetrafluoropropanol (structural formula: HGF2CF2CH20H).
A dye layer coating solution was prepared by dissolving the dye in 100 cc.

A disc-shaped polycarbonate substrate with a tracking guide (outer diameter: 120 mm, inner diameter: 15 mm, thickness:
1.2mm, track pitch: 1.6μm, group half width 20.5μm, group depth: 900λ)
The coating solution was applied onto the top using a spin code method at a rotational speed of 1100O.
After coating at a speed of rp and drying for 30 seconds, the layer thickness is 200 mm.
A recording layer of No. 01 was formed.

On the recording layer, a reflective layer with a thickness of 1300λ is formed by rough DC sputtering of Au, and on the reflective layer, a UV curable resin (trade name: 3070, manufactured by ThreeBond) is applied as a protective layer using a spin code method. After coating at a rotational speed of 1,500 rpm, the coating was cured by irradiation with ultraviolet rays using a high-pressure mercury lamp to form a protective layer with a thickness of 3 μm.

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

[Example 2] In Example 1, 2.0 g of the cyanine dye represented by formula (I) (the dye 1-1) was used instead of 2.0 g of the dye 1-2. An information recording medium was manufactured in the same manner as in Example 1 except that

[Example 3] In Example 1, 2.0 g of the cyanine dye represented by formula (I) (the dye 1-1) was used as the dye in Example 1. An information recording medium was manufactured in the same manner as in Example 1 except that

[Example 4] In Example 1, 2.0 g of the cyanine dye represented by formula (I) (the dye I-1) was used as the dye in Example 1. An information recording medium was manufactured in the same manner as in Example 1 except that

[Example 5] In Example 1, 2.0 g of the cyanine dye represented by the general formula (I) (the dye 1-1) was used instead of 2.0 g (the dye 1-9). An information recording medium was manufactured in the same manner as in Example 1 except that

[Example 6] In Example 1, a quencher was further added to the dye coating solution.
Diimmonium dye (IR
An information recording medium was produced in the same manner as in Example 1, except that 0.2 g of G-023 (manufactured by Nippon Kayaku ■) was added to prepare a dye coating liquid.

[Example 7] In Example 6, 2.0 g of the cyanine dye represented by the general formula (I) (the dye 1-1) was used instead of 2.0 g (the dye 1-2). An information recording medium was manufactured in the same manner as in Example 6 except that

[Example 8] In Example 6, 2.0 g of the cyanine dye represented by the general formula (I) (the dye 1-1) was used instead of 2.0 g (the dye 1-7). An information recording medium was manufactured in the same manner as in Example 6 except that

[Example 9] In Example 6, 2.0 g of (the above dye 1-8) was used as the dye instead of 2.0 g of the cyanine dye represented by the general formula (I) (the above dye 1-1). An information recording medium was manufactured in the same manner as in Example 6 except that

[Example 10] In Example 6, 2.0 g of the cyanine dye represented by the general formula (I) (the dye 1-1) was used instead of 2.0 g (the dye 1-9). An information recording medium was manufactured in the same manner as in Example 6 except that

[Example 11] An information recording medium was manufactured in the same manner as in Example 6 except that a substrate with a group depth of 1600λ was used instead of a substrate with a group depth of 900λ.

[Example 12] In Example 11, 2.0 g of the cyanine dye represented by the general formula (I) (the dye 1-1) was used as the dye.
An information recording medium was produced in the same manner as in Example 11 except that 2.0 g of (the above-mentioned dye 1-2) was used instead of.

[Example 13] In Example 11, 2.0 g of the cyanine dye represented by the general formula (I) (the dye 1-1) was used as the dye.
An information recording medium was produced in the same manner as in Example 11 except that 2.0 g of (the above-mentioned dye 1-7) was used instead of.

[Example 14] In Example 11, as the dye, cyanine dye represented by the general formula (I) (the dye l-1) 2, Og
An information recording medium was produced in the same manner as in Example 11, except that 2.0 g of (the above-mentioned dye 1-8) was used instead of.

[Example 15] In Example 11, 2.0 g of the cyanine dye represented by the general formula (I) (the dye 1-1) was used as the dye.
An information recording medium was produced in the same manner as in Example 11 except that 2.0 g of (the above-mentioned dye 1-9) was used instead of.

[Example 16] In Example 1, a substrate with a group depth of 400 λ was used instead of the substrate with a group depth of 900 λ, and 2,2,3,3-tetrafluoropropanol was used as the solvent for the dye layer coating solution. 1
An information recording medium was produced in the same manner as in Example 1, except that 00 cc was replaced with 90 cc of 2,2,3,3-tetrafluoropropanol and 10 cc of propylene glycol monomethyl ether.

[Comparative Example 1] In Example 1, the following dye A2. A recording medium was produced in the same manner as in Example 1 except that a dye coating liquid was prepared using Og and the thickness of the recording layer was changed from 2000λ to 1300μ.

Dye A: [Comparative Example 2] Comparative Example 1 except that 0.2 g of the above diimmonium dye (IRQ-023, manufactured by Nippon Kayaku ■) was further added as a quencher to the dye coating liquid to prepare a dye layer coating liquid. An information recording medium was manufactured in the same manner as in Comparative Example 1.

[Comparative Example 3] In Comparative Example 1, the following dye B2. An information recording medium was manufactured in the same manner as in Comparative Example 1 except that the dye coating liquid was prepared using Og.

Dye B: [Comparative Example 4] In Comparative Example 1, the layer thickness of the recording layer was changed from 1300λ to 20
An information recording medium was manufactured in the same manner as in Comparative Example 1 except that the light was changed to 00λ.

[Comparative Example 5] In Comparative Example 2, the layer thickness of the recording layer was changed from 1300λ to 20
An information recording medium was manufactured in the same manner as in Comparative Example 2 except that 00^ was used.

[Comparative Example 6] In Comparative Example 3, the layer thickness of the recording layer was changed from 1300λ to 20
An information recording medium was produced in the same manner as in Comparative Example 3 except that the material was changed to 00.

[Comparative Example 7] An information recording medium was manufactured in the same manner as in Comparative Example 4, except that the depth of the substrate group was changed from 900X to 1600λ.

[Comparative Example 8] An information recording medium was manufactured in the same manner as in Comparative Example 5, except that the depth of the substrate group was changed from 900x to 1600x.

[Comparative Example 9] An information recording medium was manufactured in the same manner as in Comparative Example 6 except that the depth of the substrate group was changed from 900λ to 1600λ.

[Comparative Example 10] In Example 16, the above dye A2. An information recording medium was produced in the same manner as in Example 16 except that Og was used to prepare the dye coating liquid.

Characteristics of the information recording media obtained in the above Examples and Comparative Examples were evaluated as follows.

[Evaluation of information recording medium 1) C/N The information recording medium obtained above is irradiated with semiconductor laser light with a wavelength of 780 nm through an objective lens with an NA of 0.5 to focus on the recording layer of the medium. While tracking inside the groove, constant linear velocity 1.3m/sec, recording power 7.0mW
, modulation frequency 720kHz (duty -33%)
The signal was recorded. And the recorded signal is 0.5mW
The C/N during playback was measured using a spectrum analyzer (TR4135: manufactured by Advantest).
Measured using

2) Reflectance When tracking into an unrecorded groove with a reproduction power of 0.5 mW using the same optical system (equipment) as in 1), the amount of reflected light (X) returning from the medium was measured with a photodetector. . Next, the medium was removed and the same photodetector was placed at the position of the medium to measure the amount of incident light (Y).

Then, (X/Y)X100 (%) was defined as the reflectance.

3) Sensitivity: 4.5 to 7.0 using the same optical system (device) as in 1)
A CD format EFM signal was recorded at a constant linear velocity of 1.3 m/sec while changing the recording power by 0.5 mW up to mW. The recorded signal was reproduced with a reproduction power of 0.5 mW, and the number of C1 error frames occurring per second was measured. The lowest recording power at which the number of C1 error frames was less than 30 was defined as the sensitivity.

Table 1 shows the compositions of the dye layer coating solutions obtained in the above Examples and Comparative Examples and the above measurement results.

Table 1 in the margin below Material name Layer thickness Groove depth Sensitivity Reflectance C/N dye/
Quen fy (X) (λ) (d)
(!'k) (dB) Example 1 1/--
200090068152 Example 2 2/--2000
90068250 Example 3 7/--20009006
8+ 50 Example 48/ --200090068
051 Example 5 9/--200090068150 Example 6 1/IRGO23200090067952 Example 7 2/IRGO23200090088050 Example 8 7/IRGO23200090067951 Example 9 8/IRGO23200090067851 Example +0 9/IRGO23200090067951
Example I+ 1/IRGO232000160057
852 Example 12 2/IRGO2320001600
57950 Example +3 7/IRGO23200016
0057851 Example 14 8/IRGO232000
160057850 Example 15 9/IRGO2320
00160057850 Example 16 1/--2000
40068050 Comparative Example I A/--1300900
67350 Comparative Example 2 A/IRGO23130090
066950 Comparative Example 3 B/--130090067
350 Comparative Example 4 A/--200090057250
Comparative example 5 A/IRGO2320009006684
9 Comparative Example 6 B/--200090067149 Comparative Example 7 A/--200016005,56950 Comparative Example 8 A/IRGO23200016005,568
50 Umbrella Standard 9 B/--200016005,
56850 Comparative Example IOA/--20004006714
9 As is clear from Table 1, information recording media (Examples 1 to 16) having a recording layer of a specific cyanine dye of the present invention
) has a significantly high reflectance and also shows a high level of C/FN. Therefore, even when a quencher is added to improve light resistance, a high reflectance can be maintained as shown in Examples 6 to 15. Also,
It can be seen that the optical disks of Examples 11 to 15 using substrates with deep group depths also have excellent recording sensitivity.

On the other hand, optical disks using dyes A and B having a benzindolenine skeleton, which are generally known to have high reflectance and excellent recording and reproducing characteristics (Comparative Examples 1 and 3)
) has a low reflectance compared to the example, and C
The reflectance cannot be said to be sufficiently satisfactory for reproducing information on a D player. Furthermore, when a quencher was added to improve light resistance (Comparative Example 2), the reflectance increased to 70.
The result is less than %. Further, although the optical disks of Comparative Examples 7 to 9 using substrates with deep group depths have slightly increased sensitivity, they are inferior to those of Examples 11 to 15 in both sensitivity and reflectance.

Claims (1)

[Claims] 1. On the substrate, there is the following general formula (I); ▲Mathematical formula, chemical formula, table, etc.▼(I) [In the formula, R^1, R^2 and R^3 each independently have a substituent. represents an optionally alkyl group, Y represents a methyl group, ethyl group or benzyl group,
^- represents an anion, n represents 1, 2 or 3, and R^2 and R^3 may be linked to each other to form a ring. ] An information recording medium comprising a recording layer capable of recording information with a laser containing a cyanine dye having a benzoindolenine skeleton represented by the following formula, and a reflective layer made of metal provided on the recording layer. 2. The information according to claim 1, wherein a pregroove is formed on the substrate, and the depth of the pregroove is in the range of 1500 to 2000 Å, and the half width thereof is in the range of 0.2 to 0.9 μm. recoding media. 3. On the substrate, there is the following general formula (I); ▲Mathematical formula, chemical formula, table, etc.▼(I) [In the formula, R^1, R^2 and R^3 each independently have a substituent. represents an optionally alkyl group, Y represents a methyl group, ethyl group or benzyl group,
^- represents an anion, n represents 1, 2 or 3, and R^2 and R^3 may be linked to each other to form a ring. ] While rotating an information recording medium comprising a recording layer capable of recording information with a laser containing a cyanine dye having a benzoindolenine skeleton represented by the following, and a reflective layer provided on the recording layer, An optical information recording method comprising recording information by irradiating the recording layer from the substrate side with a laser whose oscillation wavelength is within the range of 750 to 850 nm.