JPH04201482A - Information recording medium and optical information recording method - Google Patents

Abstract

PURPOSE:To obtain a recording medium having remarkably high reflectivity and excellent durability by forming a recording layer capable of recording information by a laser composed of at least one kind of cyanine dyes having specific indolenine skeletons onto a substrate and forming a reflecting layer consisting of a metal onto the recording layer. CONSTITUTION:A recording layer capable of recording information by a laser made up of at least one kind of cyanine dyes having indolenine skeletons shown in formula I and formula II is formed onto a substrate, and a reflecting layer composed of a metal is shaped onto the recording layer. Where R<1>, R<2> and R<3> represent an alkyl group, which may have substitutional groups within a range of 1-8C respectively independently, Q represents the alkyl group, a phenyl group or a benzil group, which may have substitutional groups within a range of 1-8 of hydrogen atoms or carbon atomicity, X<p-> represents an anion, and (p) represents 1 or 2.

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 using 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 task memory, and the like.

D RA W (Direct Read After
The basic structure of the WriteJ type optical disc is a disk-shaped substrate made of glass, synthetic resin, etc., and a metal or metalloid such as Bi, Sn, In, Te, etc.; or a cyanine-based, metal complex-based, It has a recording layer made of a quinone-based dye or the like. Note that an intermediate layer made of a polymeric material is usually provided on the surface of the substrate on which the recording layer is provided, in order to improve the flatness of the substrate, improve the adhesion with the recording layer, or improve the sensitivity of the optical disc. Often provided.

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 that corresponds to 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 such as the fact that the recording layer can be easily formed by a coating method. It has the above major advantages. However, recording layers made of dyes generally have characteristic problems such as low reflectance and low C/N of reproduced signals, and dye recording layers deteriorate over time due to light irradiation during long-term storage. It has disadvantages such as being easy to

As a recording layer made of a dye with improved reflectance and C/N ratio, JP-A-64-40382 discloses an optical disk having a recording layer made of a cyanine dye having a benzoindolenine skeleton. In addition, as a similar recording layer, JP-A No. 64-40387 discloses a dicarbocyanine dye (a methine chain containing 5
Disclosed is an optical disc provided with a recording layer comprising a tricarbocyanine dye having an indolenine skeleton (7 methine chains) and a tricarbocyanine dye having an indolenine skeleton.

Stiffness is an attempt to improve C/N by simultaneously using a tricarbocyanine dye having an indolenine skeleton while maintaining the high reflectance of a dicarbocyanine dye having a benzindolenine skeleton.

However, although the information recording medium having such a dye recording layer has relatively good C/N,
The reflectance and durability are not satisfactory.

In order to increase the reflectance, it is common practice to provide a reflective layer roughly on top of the dye recording layer. An example of this is Nikkei Electronics (107 pages, 1989
According to this paper, the dye used in the recording layer of the recording medium is unknown, but the recording method involves melting the dye by absorption of the laser in the dye recording layer. It is disclosed that the plastic substrate is heated accordingly, and the substrate bulges toward the recording layer, thereby forming bits. This reflective layer is a vapor-deposited gold film. According to the studies of the present inventors, when the cyanine dye having the benzindolenine skeleton is used in this dye recording layer, it is possible to obtain a relatively high C/C ratio.
It is possible to obtain an optical disk with high N and also high reflectance and recording sensitivity.

Even with D RAW type optical discs, in high-density recording of CD format fZ (CD-DRAW), the constant linear velocity is 1.
It is necessary to record the above-mentioned signals at a slow speed of 2 to 1.4 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 reflectance of the optical disc be about 70%.

Furthermore, as mentioned above, it is preferable for optical discs to maintain excellent characteristics (have excellent durability) even after long-term storage, but the indolenine dyes have poor durability, especially solvent resistance. It wasn't enough. In other words, light resistance can be improved by using a doublet oxygen quencher together with a dye, but for example, in such a dye recording layer that does not have sufficient solvent resistance,
When a room floor is waxed or sprayed with pest extermination sprays, the dye recording layer may be attacked by the solvent vapor contained therein, and improvements to this problem are desired.

In addition, in order to improve the reflectance, a metal reflective layer must be provided on the dye recording layer by sputtering Au or the like, or the state of the dye recording layer film may vary depending on the sputter linking conditions. One example of this is that the recording/reproducing characteristics such as C/N are likely to deteriorate. For example, in an RF (alternating current) sputtering device that can be used for both metals and metal oxides, if an Au reflective layer is provided on the recording layer of the indolenine dye, the recording and reproducing characteristics of the recording layer will be impaired. Easy to fall. For this reason, when sputtering metal onto the dye recording layer, instead of RF (alternating current) sputtering, a DC (direct current) sputtering device that can only perform sputter linking of metal is generally used. Therefore, it is clear that it would be advantageous if sputtering could be performed using RF (alternating current) sputtering, which can also be used for turquoise materials such as .

Therefore, it is desired to develop an optical disk with significantly high reflectance, excellent durability, and wide applicability to manufacturing conditions.

[Object of the invention] The object of the present invention is to provide an information recording medium having a recording layer made of a dye and a reflective layer thereon, which has a significantly high reflectance and excellent durability. do.

Another object of the present invention is to provide an information recording medium having 11 recording layers and a reflective layer in one of them, in which the recording and reproducing characteristics hardly deteriorate due to differences in the formation conditions of the reflective layer. shall be.

[Summary of the Invention] The present invention provides the following general formula (Ia); R2 on a substrate.
1(3R2R3 1/p (XP-) (I a ) and the following general formula (Ib); R2R3R2R1 1/p (X”) (I b
) [However, R1, R2 and R3 each independently represent an alkyl group which may have a substituent having 1 to 8 carbon atoms, and Q is a hydrogen atom or a represents an alkyl group, phenyl group or benzyl group which may have a substituent in the range of 1 to 8, x
p- represents an anion, and p represents 1 or 2] A recording layer capable of recording information with a laser is provided, which is made of at least one type of cyanine dye having an indolenine skeleton represented by: The information recording medium is provided with a reflective layer made of metal on the recording layer.

Furthermore, the present invention □ provides the above general formula (Ia
) and a recording layer made of at least one cyanine dye having an indolenine skeleton represented by the above general formula (Ib), and further provided with a reflective layer made of metal on the recording layer. There is also an optical information recording method in which information is recorded by irradiating a laser onto the recording layer from the substrate side while rotating the recording layer.

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

1) The information recording medium, wherein the recording layer contains a dye having an absorption maximum on the shorter wavelength side than the absorption maximum wavelength of any dye contained in the recording layer.

2) The above-mentioned recording layer further has the following general formula %) each independently represents an alkyl group which may have a substituent having a carbon number of 1 to 8, and l( +7
represents a hydrogen atom or an alkyl group, phenyl group or pencil group which may have a substituent having 1 to 8 carbon atoms; Yaq- represents an anion; q is 1 or 2; and A1 and A2 are
Each represents an atomic group for forming a benzene ring which may independently have a substituent] or the following general formula (n b); N+ 17s (Yb''-) [However, R21,923 and [24 each independently represents an alkyl group which may have a substituent having 1 to 8 carbon atoms, R26 represents a hydrogen atom or an acyl group having 1 to 8 carbon atoms, L represents a linking group formed by bonding 2,4 or 6 methine groups which may have substituents, and A3 represents a benzene ring or naphthalene which each independently may have a substituent. Represents an atomic group for forming a ring, and 8- may be substituted with a halogen atom or an alkyl group or alkoxy group which may have a substituent having 1 to 8 carbon atoms. represents a phenyl group, and Yb'- is
represents an anion, and 1 represents 1 or 2.] The information recording medium described above is characterized in that it contains a cyanine dye having an indolenine skeleton represented by the following formula.

3) The above-mentioned recording layer further has the following formula (Ha); represents an alkyl group which may have a substituent in the range of 1 to 8,
R3? represents a hydrogen atom or an alkyl group optionally having a substituent having 1 to 8 carbon atoms, a phenyl group or a benzyl group, Ya''- represents an anion, and n represents 1 or 2] The information recording medium described above, comprising a cyanine dye having an indolenine skeleton represented by the following.

4) The information recording medium described above, wherein the recording layer contains a quencher having an absorption maximum on the longer wavelength side than the absorption maximum wavelength of any of the dyes contained in the recording layer.

5) The above-mentioned information recording medium, wherein the above-mentioned recording layer further contains another dye whose absorption maximum is 20 nm or more lower than the absorption maximum of any of the cyanine dyes represented by the above-mentioned general formula (Ia) or (Ib).

6) The above-mentioned information recording medium, wherein the above-mentioned recording layer further contains another dye having an absorption maximum higher than 650 nm.

7) The mixing ratio of the cyanine element represented by the above general formula (Ia) or general formula (Ib) and another dye having an absorption maximum on the short wavelength side is 91:9 by weight.
~40: 1 above, characterized by being in the range of 60
) information recording medium.

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

9) The above metal is Cr, Ni, Pt, Cu, Ag, Au,
AJ! and stainless steel.

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

l) The optical information recording method, wherein the recorded information is in a CD format.

2)-The rotation of the information recording medium in F is 1.2 to 2.8 m/
An optical information recording method characterized by being carried out at a constant linear velocity of seconds.

3) The optical information recording method described above, wherein the oscillation wavelength of the laser is in the range of 750 to 850 nm.

Note that the maximum absorption of the dye in the present invention refers to the maximum absorption of the dye layer formed on the substrate.

[Effects of the Invention] The information recording medium of the present invention is provided with a recording layer made of a specific dye represented by the general formula (Ia) or (Ib) on the substrate-F as described above, A reflective layer made of metal is laminated on a recording layer. By adopting such a configuration, durability can be improved while maintaining recording and reproducing characteristics such as reflectance and C/N at a high level. That is, even when the information recording medium of the present invention is stored under harsh conditions such as being exposed to solvent vapor, the initial recording/reproducing characteristics such as recording sensitivity, C/N, modulation degree, etc., and reflectance are almost unchanged. Because it never decreases,
It can be said that the recording medium has excellent durability. This is thought to be because the dye having the above specific structure forms a film with a hard and dense structure when it becomes a recording layer.

Furthermore, the information recording medium of the present invention is a recording medium in which the recording and reproducing characteristics hardly deteriorate due to differences in the formation conditions of the reflective layer. That is, when sputtering metal onto the dye recording layer, a DC (direct current) sputtering device that can only perform metal sputtering is generally used instead of RF (alternating current) sputtering. When used, the recording and reproducing characteristics of the recording layer will not be impaired even if an Au reflective layer is provided on the recording layer using an RF (alternating current) sputtering device that can be used for both metals and metal oxides. . Therefore, on the recording layer of the present invention, RF
Information recording media with excellent characteristics can be manufactured using either sputtering or DC sputtering equipment.

[Detailed Description of the Invention] The information recording medium of the present invention has the above general formula (Ia
) or (Ib) A recording layer made of a specific cyanine dye having a benzindolenine skeleton is provided, and a reflective layer is further provided on the recording layer.

2 The present inventors have discovered that a recording layer can be provided on a substrate using a dye that can be formed into a layer by coating, which is a simple manufacturing method, and an optical disc with a reflective layer formed thereon. We have continued to conduct intensive studies to improve this and obtain optical tiffs that have significantly high reflectance, excellent durability, and whose characteristics are unlikely to be adversely affected by differences in the conditions for forming the reflective layer.

According to studies by the present inventors, by providing a recording layer made of a specific cyanine dye having a benzoindolenine skeleton represented by the above-mentioned formula (Ia) or (rb) as a recording layer of an optical disc, the above-mentioned reflectance It has also become clear that durability such as solvent resistance can be improved without deteriorating recording and reproducing characteristics.

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. Examples of substrate materials of the present invention include glass; acrylic resins such as polymethyl methacrylate; vinyl chloride resins such as polyvinyl chloride and vinyl chloride copolymers; epoxy resins, amorphous polyolefins, polycarbonates, and polyesters; They may be used together 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/sulfonate copolymer, styrene/vinyltoluene copolymer, chlorosulfonated polyethylene, nitrocellulose, polyvinyl chloride, chlorinated polyolefin,
Polymer materials such as polyester, polyimide, vinyl acetate/vinyl chloride copolymer, ethylene/vinyl acetate copolymer, polyethylene, polypropylene, polycarbonate, etc.:
and organic substances such as silane coupling agents.

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 projections and depressions representing information such as an address signal. When using a resin material such as the above-mentioned polycarbonate, it is preferable that the resin material be directly formed into a group on the substrate by injection molding or extrusion molding.

Croup formation may also be carried out by providing a pre-groove layer. As the material for the pregroove layer, a mixture of at least one monomer (or oligomer) of acrylic acid monoester, diester, triester, and tetraester and a photopolymerization initiator can be used.

The pre-groove layer was formed by first coating a mixture of the above-mentioned acrylic ester and polymerization initiator on a densely made matrix (stamper), and then placing the substrate on top of this coating solution layer. Thereafter, 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.

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

The recording layer is a layer consisting of a dye consisting of at least one kind of cyanine dye having a benzoindolenine skeleton having a structure represented by the following general formulas (Ia) and (Ib), or a binder for dispersing these dyes. This is a layer containing

General formula (Ia); 1'/p (X'-) (I a )
and general formula (Ib); R2R3R2R3 RI R11/p
(X”) (I b ) [However, R1, R2 and R3 each independently represent an alkyl group which may have a substituent having 1 to 8 carbon atoms, and Q is a hydrogen atom. or the number of carbon atoms is 1 to 8
represents an alkyl group, phenyl group, or benzyl group that may have a substituent within the range of , xp ~ represents an anion, and p is! or 2] In the general formula (Ia) and the general formula (Ib), R
The alkyl group represented by 1 is an alkyl group that may have a substituent having 1 to 8 carbon atoms,
Mention may be made of groups such as methyl, ethyl, n-propyl, n-butyl, isobutyl and 2-ethylhexyl, preferably alkyl groups having 1 to 6 carbon atoms (for example methyl, ethyl, n-propyl, n -butyl, isobutyl), and its optionally substituted substituents include a fluorine atom and an alkoxy group.

Particularly preferred is an unsubstituted alkyl group.

The alkyl group represented by R2 and R3 includes an unsubstituted alkyl group having 1 to 8 carbon atoms (specific examples, methyl,
(ethyl, propyl) are preferred, and methyl or ethyl groups are particularly preferred.

stomach.

The group represented by Q is preferably a hydrogen atom, a methyl group, an ethyl group, a phenyl group, or a benzyl group, and particularly preferably a hydrogen atom, a methyl group, or a benzyl group.

In addition, preferred anions represented by X include halide ions (for example, C11-, Br-1I-)
, sulfonate ions (e.g. CH3 disulfonate ion), 5bF6-1cno4-1BF, -1 metal complex ions (e.g.).

Among these, particularly preferred anions are cio, -1
PF6- and i.

The cyanine dye having a benzindolenine skeleton represented by the above formula (ra) or (Ib) is
It has a high reflectance among dyes, and is also excellent in recording and reproducing characteristics such as recording sensitivity and C/N. The cyanine dye having a benzindolenine skeleton represented by the above-mentioned formula (Ia) or (Ib) generally has a maximum absorption wavelength of around 760 nm or less, which is 780 nm, which is the oscillation wavelength of the laser beam used for recording and reproduction. It has the characteristics that light absorption is relatively small and reflectance is high in the wavelength bands before and after it.

Specific examples of compounds represented by the above formulas include I-1 to I-22 below.

C.I.O.

knee 3 I-5' Eero C10゜ knee 10 PF’ knee 11 ■・12 C10゜ knee 13 C.I.O.

■・14 CIO4 knee 15 F6 D・16 C.I.O.

Knee 17 Knee 18 Knee 19 Knee 20 Knee 21 Knee 22 The above formula (Ia) or - as shown in the above specific example
The cyanine dye having an indolenine skeleton represented by the formula (Ib) is disclosed in the above-mentioned JP-A-64-40382 and JP-A-64-40382.
It is included in the general formula of the dye used in the recording layer of the optical tape in each publication of No. 4-40387.

The cyanine dye having an indolenine skeleton represented by the above formula (Ia) or (Ib) can be synthesized by a conventional method, and the synthesis method will be explained below by giving specific examples.

Synthesis Example 1 Synthesis of Compound 1-1 ・To 4 g of 2,3.3-trimethyl-6,7-benziindolenine, 3.8 g of methyl paratoluenesulfonate and 5 mA of methyl isobutyl ketone were added and heated in an oil bath at 120°C for 4 hours. The mixture was heated and stirred. After cooling, 20 mJ2 of ethyl acetate was added and stirred, the supernatant was removed, and this operation was repeated twice. Malondialdehyde cyanyl hydrochloride in the residue 2.
2 g of acetone, 150 mJ2 of acetone, 2 ml of acetic anhydride, and 4.6 mff1 of triethylamine were added thereto, followed by rapid heating for 2 hours. The solvent was distilled off, 100 mJ2 of water was added to the residue, and the resulting crystals were collected by filtration and washed with water to give 7.4 g of 1.3.3-tolumethyl-2-[5-(1,3,3-1 Limethyl, 6,7-
Benzoindolin-2-yritene)-1,3-pentadienyl]-6,7-henzo 3H-indowaumbalatoluenesulfonate was obtained. After adding 250ml of methanol to 3g of these crystals and dissolving them, 60ml of
% aqueous solution of perchloric acid was added, and the resulting crystals were collected by filtration and washed with methanol to obtain Compound 1-1.

Yield: 1.7 g Melting point: 224-225°C Synthesis Examples 2 and 3 By using Sowazowa, the corresponding 2-methyl compound, or 2-benzyl derivative in place of malondialdehyde cyanyl hydrochloride in Synthesis Example 1, the following can be obtained. The compound was obtained.

Compound 1-17: Melting point 219-221°C Compound 1-21
: Melting point 234-236°C In the present invention, the above formula (Ia
) or - In combination with a dye that is a cyanine dye represented by formula (Ib) (hereinafter also referred to as dye A), it is possible to use another dye having an absorption maximum at a shorter wavelength than the absorption maximum of the cyanine dye to achieve high reflection. This is preferable in terms of obtaining the ratio. In addition, the absorption maximum of such another dye (hereinafter also referred to as dye B) is 20 nm or more lower than the absorption maximum of the cyanine dye represented by the above-mentioned formula (Ia) or -formula (Ib) to obtain a high reflectance. preferred above. Furthermore, the absorption maximum wavelength of the dye B is preferably higher than 650 nm, especially in order not to reduce the recording sensitivity. Any type of dye may be used as long as the above conditions are satisfied. It is preferable to use a dye that has excellent compatibility with dye A represented by the formula and can be dissolved in the same organic solvent. By forming a uniform dye layer, recording and reproducing characteristics such as C/N and modulation degree become superior. Preferably, such dyes are polymethine dyes such as cyanine dyes, oxonol dyes, pyrylium dyes, and thiopyrylium dyes, and in particular, dianine dyes having an indolenine skeleton represented by the following general formula (lla) or (rlb). is preferred.

R13RI4 RIS R+6j RII R12 ]/q (Ya”) [However, Rth, l(+2, R13, R14, R1!,
and R16 each independently represent an alkyl group which may have a substituent having 1 to 8 carbon atoms, and R17 represents a hydrogen atom or a substituent having 1 to 8 carbon atoms. represents an alkyl group, phenyl group or benzyl group which may have a substituent, Yaq- represents an anion, q represents 1 or 2, and A1 and A2 independently represent a substituent. [represents an atomic group for forming a benzene ring which may have] ・R23R24 N and R24 (ybm-) [However, R21, R23 and R24 each independently have a carbon atom number in the range of 1 to 8 represents an alkyl group which may have a substituent, R28 represents a hydrogen atom or an acyl group having 1 to 8 carbon atoms, and L represents 2.4 or 6 which may have a substituent. It is a linking group formed by bonding two methine groups, A2 represents an atomic group for forming a benzene ring or naphthalene ring which may have a substituent, and Ar' is a halogen atom or the number of carbon atoms. represents an alkyl group which may have a substituent in the range of 1 to 8 or a phenyl group which may be substituted with an alkoxy group, Y-1 represents an anion, and m is 1 or 2. ] The cyanine dyes having an indolenine skeleton represented by the above-mentioned formula may be used alone or in combination of two types as the dye B.

Among the cyanine dyes represented by (nb) above, preferred dyes include dyes represented by the following general formulas (Uc) to (IIe).

R43R44 [ 1/j (YdJ-) R43R44 1/j (Yd'-) R43R44 N or 1... 1/j (YdJ-) [-In formulas (nc) to (Ile), R41, R4
3 and R44 each independently have 1 to 8 carbon atoms.
represents an alkyl group which may have a substituent within the range of , and R47 is a hydrogen atom or an alkyl group which may have a substituent having 1 to 8 carbon atoms, a phenyl group, or represents a benzyl group, R48 represents a hydrogen atom or an acyl group having 1 to 8 carbon atoms, and A3 represents an atomic group for forming a benzene ring or naphthalene ring which may have a substituent; , Ar2
represents a phenyl group optionally substituted with a halogen atom or an alkyl group optionally having a substituent having 1 to 8 carbon atoms, or an alkoxy group;
In addition to the dyes represented by the above (Ila) to (IIe), as the co-dye B which represents a dJ-anion and which also represents jl or 2, in addition to the dyes represented by the above (Ila) to (IIe), the following general formulas (Hf) to (nh) are used. Dyes that can be used can also be used.

1 (53R54 R53R54 R53R54 [-In formulas (Iff) to (n h), R51, R
53 and R54 each independently have 1 to 1 carbon atoms;
represents an alkyl group which may have a substituent within the range of 8, and R57 is a hydrogen atom or an alkyl group having 1 to 8 carbon atoms.
represents an alkyl group, phenyl group or benzyl group which may have a substituent within the range of, A3 represents an atomic group for forming a benzene ring or naphthalene ring which may have a substituent, Ar3 represents a phenyl group which may be substituted with a halogen atom or an alkyl group which may have a substituent having 1 to 8 carbon atoms, or a phenyl group which may be substituted with an alkoxy group] In Ila) to (Ilh), [11,
The alkyl groups represented by R12, R21, R22, 1 (41 and R61) include methyl,
Mention may be made of groups such as ethyl, n-propyl, n-butyl, isobutyl and 2-ethylhexyl, preferably alkyl groups having 1 to 6 carbon atoms (e.g. methyl, ethyl, n-propyl, n-butyl). , isobutyl), and its optionally substituted substituents include a fluorine atom and an alkoxy group. Particularly preferred is an unsubstituted alkyl group.

In general formulas (Ila) to (Ilh), R13,
R14, II5, Rlg, R23, [24, R2S
, R26, R43, R44, R53 and 1 (54) is preferably an unsubstituted alkyl group having 1 to 6 carbon atoms (specific examples: methyl, ethyl), particularly preferably a methyl group or ethyl group. It is the basis.

- Formulas (II a), (II c), (II d), (
In Ilg) and (IIf), R17, R27
, R47 and R67 are hydrogen atoms and have 1 to 1 carbon atoms.
an alkyl group which may have a substituent within the range of 6;
A phenyl group or a hensyl group is preferred, and a hydrogen atom, methyl group, ethyl group, benzyl group or phenyl group is particularly preferred.

In general formula (IIa), A1 and A2 are preferably each independently selected from an atomic group for forming an unsubstituted benzene ring, a methyl group, a chlorine atom, a fluorine atom, a methoxy group, or an ethoxy group. Represents an atomic group for forming a benzene ring substituted with one or two groups.

In general formulas (nb) to (nh), A3 and A4 are each preferably a benzene ring or a naphthalene ring which may be independently substituted with a phenyl group, a cyano group, a methyl group, a chlorine atom, a fluorine atom, or a methoxy group. Represents an atomic group for forming . Particularly preferred is an unsubstituted benzene ring or naphthalene ring.

In general formulas (IIc) to (ah), 928 and R4B are preferably a hydrogen atom, a methoxy group, an ethoxy group, or a benzoyl group. Particularly preferred are a hydrogen atom and a methoxy group.

-In formulas (nb) to (nh), Ar',
Ar2 and Ar3 are preferably phenyl, 4-chlorophenyl, 4-methylphenyl, 3-methoxyphenyl and 3,5-dichlorophenyl, particularly preferably phenyl.

In addition, preferred anions represented by yaq-1Y-- and Yd'- are those represented by the above-mentioned formula (Ia
) or -x'- in the formula (Ib).

Specific examples of compounds represented by the above-mentioned formulas include the following nt to -36.

Margin below Any 2 CIO,’ II.3 C10゜ Engineering=-5 Coo.

F any7 any8 l04 II・9 CIO4' II・11 Any 12 C.I.O.

ll-1:I F any15 C.I.O.

Any 16 PF6 any17 Any 18CIO4’ C10゜ ClO4 Any21 Engineering l-22 Shir13 ClO4'Ω any24 (CH214So4 any25 ■■・26 〇H,■ I knee 27 H3Br Engineering l-28 Engineering ■・29 Eating work any30 any31 Any 32 any33 CH.

Any34 Shinn3 Any35 Shifi3 Any36 The specific cyanine dyes represented by the above general formulas (IIa) to (nh) are, for example, the dyes used in the recording layer of the optical disc of JP-A No. 59-55795. It is partially included in the general formula. The cyanine dye is based on the chemistry of heterocycle compounds (The Ch.
eIIIstry of Heterocycle
Comp.

and) series of cyanine dyes and related compounds ([
:yanine Dyes and Re1ated
Compounds, John Wiley & 5
ons, New York, London, t9
(published in 1964).

Further, as another dye B used in combination with dye A, which is a cyanine dye represented by the above general formula (Ia) or general formula (Ib), the following general formula (mb): R31R32 1/n (Ycn-) [However, 1 (31, R32, R33, R]4, R35 and R36 each independently represent an alkyl group which may have a substituent having 1 to 8 carbon atoms, and R3? is a hydrogen atom or represents an alkyl group, phenyl group or hensyl group which may have a substituent having 1+-8 carbon atoms, Yan- represents an anion, and n represents 1 or 2; A cyanine dye having an indolenine skeleton represented by the following may also be used.

Furthermore, in order to obtain good recording sensitivity, the mixing ratio of dye A, which is a cyanine dye represented by the above general formula (Ia) or general formula (Ib), and dye B, which has an absorption maximum on the shorter wavelength side than the dye, is determined. So, the weight ratio is 91:9 to 40:60
It is preferably in the range of 82:18-50
: Preferably in the range of 50.

In order to improve light resistance, it is preferable to use various dyes known as so-called singlet oxygen quenchers, such as compounds represented by the following general formulas (m), (mV), or (V).

(However, [Catl"" represents a nonmetallic cation such as tetraalkylammonium, M represents a transition metal atom such as Ni, and 2 and Z represent an optionally substituted benzene ring, 2-thioxet- 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-... (TV) [In the formula, R has a substituent] (V) [In the formula, R has the same meaning as in general formula (IV)] , Q represents the same anion as the general formula (m)]・The above general formula (
Specific examples of quenchers represented by III), (rV) or (V) include PA-1006 (Mitsui Toatsu Fine ■), IRG-023, IRG-022 and I
Examples include RG-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 general formula (1).

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; Fluorinated 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 metal parts 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 3000, preferably 500 to 2
It is in the range of 500 points. 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 blade 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,
It is necessary to provide a reflective layer for the purpose of improving C/H and reflectance during information reproduction.

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, 2r, Hf, VINb, Ta, Cr, Mo
%W, Mn, Re.

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

Pt, Cu, Ag, Au, Zn, C
d, AN, Ga, In, Si, Ge,
Mention may be made of metals and semimetals such as Te, Pb, Po, Sn, and Bi, or stainless steel.

Among these, preferred are Cr, Ni, Pt, C
u, 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 layer thickness of the reflective layer is generally in the range of ioo to 3000X.

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 Si0,5in
Examples include inorganic substances such as 2, MgF2, SnO2, and Si3N4; organic substances such as thermoplastic resins, thermosetting resins, and LIV curable resins.

The protective layer can be formed, for example, by laminating a film obtained by extrusion of plastic onto the recording layer (or silver salt layer or reflective layer) and/or onto the substrate 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, it is also possible to form a film by dissolving them in an appropriate solvent to prepare a coating solution, then applying this coating solution and drying it. can. 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. 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. General formula (Ia) or general formula (Ib)
) An information recording medium containing Dye A, which is a cyanine dye having an indolenine skeleton, has a high reflectance among dye-based optical disks, and has relatively low recording and reproduction characteristics such as recording sensitivity and C/N. It is excellent and has even improved durability.

In particular, together with the cyanine dye (dye A) having an indolenine skeleton represented by the above general formula (Ia) or general formula (Ib), the dye B has a maximum absorption on the shorter wavelength side.
When using this, it is possible to improve the reflectance without substantially reducing recording/reproducing characteristics such as recording sensitivity, C/N, modulation degree, etc.

That is, the above general formula (Ia) or general formula (Ib
The cyanine dye (dye A) having an indolenine skeleton represented by ) has a maximum absorption wavelength of 760 nm or less,
78, which is the oscillation wavelength of the laser beam used for recording and reproduction.
In a wavelength band around 0 nm, light absorption is relatively small and the sum of reflectance and transmittance is large (generally, reflectance is high). For example, the wavelength of laser light used in CD players to play CD format signals is typically 780 nm. Therefore, in order to further increase the reflectance, is it possible to increase the light transmittance by reducing the thickness of the dye layer and increase the amount of light reflected by the reflective layer? With this method, recording and reproducing characteristics such as C/N and modulation degree tend to deteriorate. By using dye B having an absorption maximum on the shorter wavelength side than the cyanine dye (dye A), the reflectance can be increased without deteriorating the recording and reproducing characteristics. Such a dye having an absorption maximum on the shorter wavelength side than that of dye A has a light absorption rate smaller than that of dye A at around 780 nm, which is the oscillation wavelength of the laser, and conversely, the sum of reflectance and transmittance becomes larger. Naturally, if the reflectance is high, the reflectance of the optical disc to the laser beam will also be high, but even if the reflectance is low and the transmittance is high, the transmitted light will be reflected by the reflective layer provided on the recording layer. The reflectance of the optical disc is improved.

Since the increase in reflectance improves the C/N and the modulation degree, the recording and reproducing characteristics are hardly deteriorated (preferably by using the additive amount within the above range). On the other hand, since dye B has an absorption maximum on the shorter wavelength side than dye A, there is a concern that the recording sensitivity may decrease, but if they are used in combination, the recording sensitivity is unlikely to decrease.

Optical discs with such extremely high reflectance and excellent recording and reproducing properties can maintain 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 an optical disk generally decreases, but the information recording medium of the present invention has a significantly high reflectance of around 70%, so even if a quencher is added, the reflectance of the optical disk is significantly high. can be played on a commercially available CD player. Therefore, an optical disc having high reflectance and excellent light resistance can also be obtained.

A method for recording and reproducing information using an information recording medium is performed, for example, as follows.

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, in the present invention, 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, information may be recorded due to changes in the refractive index due to build-up deformation of the substrate, discoloration of the recording layer, changes in association state, etc. in general,
The recording light is 500 nm to 900 nm (preferably 7
A semiconductor laser beam having an oscillation wavelength in the range (50 nm to 850 nm) is used.

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

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

[Example 1] 2.0 g of the cyanine dye represented by the general formula (Ia) (the dye 1-17) as the dye A was added to 2.2, 3.
3-tetrafluoro-1-propertool (structural formula: HC
FzCF2CH20H) Dissolved in 100cc
A dye layer coating solution was prepared.

A disc-shaped polycarbonate substrate with a tracking kite (outer diameter: 120 mm, inner diameter: 15 mm, thickness:
1.2mm, track pitch = 1.6μm, group width: 0.5μm, group depth: 900λ), the coating solution was applied by the spin code method at a rotational speed of 1100Orp, and then dried for 30 seconds. A recording layer having a layer thickness of 1300λ was formed.

A reflective layer having a thickness of 1300λ was formed on the recording layer by sputtering Au using a DC (direct current) sputtering device.

A UV curable resin (trade name: 3070, manufactured by Three Pond Co., Ltd.) was applied as a protective layer onto the above reflective layer using a spin code method at a rotational speed of 1500 rpm, and then cured by irradiating ultraviolet rays with a high-pressure mercury lamp. A protective layer having a layer thickness of 3 μm was formed.

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, a diimmonium compound (IR) having the following structural formula was added to the dye coating solution as a quencher.
An information recording medium was produced in the same manner as in Example 1, except that 0.2 g of Q-023 (manufactured by Nippon Kayaku ■) was added to prepare a dye layer coating solution.

[Example 3] In Example 1, as the dye A, the general formula (Ia)
1.6g of 2゜0g of the dye (1-17) represented by
and further, as dye B, the dye (ff-,1)0
．． An information recording medium was produced in the same manner as in Example 1 except that 4 g was used.

[Example 4] In Example 3, a diimmonium compound (IR) having the above structural formula was added to the dye coating solution as a quencher.
An information recording medium was produced in the same manner as in Example 3, except that 0.2 g of G-023 (manufactured by Nippon Kayaku ■) was added to prepare a dye layer coating solution.

[Example 5] In Example 3, as the dye A, the general formula (Ia)
Instead of the dye (1-17) represented by the dye (
An information recording medium was manufactured in the same manner as in Example 3 except that Example 1-21) was used.

[Example 6] In Example 5, a diimmonium compound (IR) having the above structural formula was added to the dye coating solution as a quencher.
An information recording medium was produced in the same manner as in Example 5, except that 0.4 g of G-023 (manufactured by Nippon Kayaku ■) was added to prepare a dye layer coating solution.

[Example 7 In Example 4, the dye (II-1) was used as the dye B.
An information recording medium was produced in the same manner as in Example 4 except that the dye (II-27) was used instead.

[Comparative Example 1] In Example 1, the dye A of the general formula (Ia)
An information recording medium was produced in the same manner as in Example 1, except that the following dye was used in place of the cyanine dye represented by (dye 1-17).

CIO,' [Comparative Example 2] Comparative Example 1 except that 0.4 g of the above diimmonium compound (IRG-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.

Table 1 shows the compositions of the dye coating solutions obtained in Examples 1 to 7 and Comparative Examples 1 to 2.

Margin Table 1 Material name [Weight ratio] Dye A / Dye B / Quencher - Example 1 1-17 [100] / - - / - Example 2 I
-17[100] /--/IRGO23[10] Example 3 1-17[80]/II -1[20]/-
Example 4 1-17[80]/ll-1[20]/I
RGO23[10] Example 5 1-21[80]/n
-1[20]/ -One Example 6 1-21[80]/
ll-1[20]/IRGO23[20] Example 7 1
-17[80]/II -27[20]/IRGO2
3 [10] Comparative example ID [100F/ --/
--Comparative example 2 D [100F / --/IR
GO23 [20] Below Margin Examples 8 to 14 and Comparative Examples 3 to 4 described below were carried out by changing only the conditions for forming the reflective layer from the above Examples 1 to 7 and Comparative Examples 1 to 2.

[Example 8] In Example 1, the sputtering for forming the reflective layer was replaced with a DC (direct current) sputtering device and an RF (alternating current) sputtering device was used.
An information recording medium was manufactured in the same manner as in Example 1 except that a sputtering device was used.

[Example 9] In Example 2, the sputtering for forming the reflective layer was performed using RF (alternating current) instead of the DC (direct current) sputtering device.
An information recording medium was manufactured in the same manner as in Example 2 except that a sputtering device was used.

[Example 10] In Example 3, the sputtering for forming the reflective layer was performed using RF (alternating current) instead of the DC (direct current) sputtering device.
An information recording medium was manufactured in the same manner as in Example 3 except that a sputtering device was used.

[Example 11] In Example 4, the sputtering for forming the reflective layer was performed using RF (alternating current) instead of the DC (direct current) sputtering device.
An information recording medium was manufactured in the same manner as in Example 4 except that a sputtering device was used.

[Example 12] In Example 5, the sputtering for forming the reflective layer was performed using RF (alternating current) instead of the DC (direct current) sputtering device.
An information recording medium was manufactured in the same manner as in Example 5 except that a sputtering device was used.

[Example 13] In Example 6, the sputtering for forming the reflective layer was performed using RF (alternating current) instead of the DC (direct current) sputtering device.
An information recording medium was manufactured in the same manner as in Example 6 except that a sputtering device was used.

[Example 14] In Example 7, the sputtering for forming the reflective layer was performed using RF (alternating current) instead of the DC (direct current) sputtering device.
An information recording medium was manufactured in the same manner as in Example 7 except that a sputtering device was used.

[Comparative Example 3] Comparative Example 1 was carried out in the same manner as in Comparative Example 1, except that the RF (alternating current) sputtering device was used instead of the DC (direct current) sputtering device for the sputtering to form the reflective layer. An information recording medium was manufactured.

[Comparative Example 4] In Comparative Example 2, sputtering for forming the reflective layer was performed using RF (alternating current) instead of a DC (direct current) sputtering device.
An information recording medium was manufactured in the same manner as Comparative Example 2 except that a sputtering device was used.

Table 2 shows the compositions of the dye coating solutions obtained in Examples 8 to 14 and Comparative Examples 3 to 4.

Table 2 Material name [Weight ratio] Dye A / Dye B / Quencher - Example 8 1-17 [100] /--/- Example 9 1-
17[100]/--/IRGO23[10] Example 1
0 r -17[80]/■-1[2(I]/-Example 11 1-17[80]/ll-1[20]/IR
GO23 [JO] Example 12 1-21 [80]/l1
-1 [20]/- Example 13 1-21 [80]/l
l-1[20]/IRGO23[20] Example 14 1
-17[80]/ll-27[20]/IRGO23[
10] Comparative Example 3 D (too]/ −−/−−
Comparative example 4 D [+oo] / --/IRGO
23 [20] or less margin Regarding the dyes and quenchers used in the above examples and comparative examples, 2,2,3.3-tetrafluoro-1-
A coating solution was prepared by dissolving it in propatool, and this was coated on a glass plate to form a dye layer with a layer thickness of about 1300λ, and the maximum absorption wavelength was determined. The results are as follows.

1-17: 720 nm I-21: 725 nm 11-1: 6F 5 nm II-27: 380 nm IRG-023: 940 nm Dye D: 720 nm [Evaluation of information recording medium] l) Reflectance Information recording medium obtained above For wavelength 780nm
Semiconductor laser light is irradiated through an objective lens with an NA of 0.5, focused on the recording layer of the medium, and at a constant linear velocity of 1.3.
Amount of reflected light returned from the medium (X) when tracking inside an unrecorded groove at m/sec and reproduction power of 0.5 mW
was measured with a photodetector. Next, the nail medium was removed and the same photodetector was placed at the position where the medium had been, and the amount of incident light (Y) was measured.

Then, (X/Y) x 100 (%) was defined as the reflectance.

2) C/N j Using the same optical system (device) as in 1), record power while tracking the inside of the groove at a constant linear velocity of 1.3 m/sec with a semiconductor laser. A signal with a modulation frequency of 720 kHz (duty - 33%) was recorded at 7.0 mW. The recorded signal was then reproduced with a reproduction power of 0.5 mW, and the C/N during reproduction was measured using a spectrum analyzer (TR4135: manufactured by Atopan Test Co., Ltd.).

3) Sensitivity Using the same optical system (equipment) as in 1), the information recording medium obtained above was heated with a semiconductor laser at a constant linear velocity of 1.3 within the groove.
While tracking m/s and changing the recording power,
A signal with a modulation frequency of 720 kHz (duty -33%) was recorded, and the lowest recording power indicating the C/N obtained in 2) above was determined.

4) Solvent resistance The information recording media obtained in Examples 1 to 7 and Comparative Examples 1 to 2 (media in Table 1) were placed in a container saturated with cyclohexane vapor at room temperature for 6 hours. After standing, the C/N as described in 2) above was measured.

The above measurement results are shown in Table 3 (measurement results in Table 1) and 4.
The results are shown in the table (measurement results in Table 2).

Table 3 with margin below Reflectance C/N Sensitivity Solventivity (%) (d B ) (mlf) C/N (
dB) Example 1 68 50 5.550 Example 2 67 50 5.550 Example 3 7
4 50 6.0 50 Example 4 72
50 6.050 Example 5 73 51 6
．． 051 Example 6 71 51 6.051 Example 7 76 50 6.050 Comparative Example 1
73 50 6.049 Comparative example 2 69
50 6.048 As is clear from Table 3, the optical disks (Examples 1 to 7\) having recording layers made of the specific cyanine dye of the present invention have high reflectance and C/N
It can be seen that the C/N ratio after the solvent resistance test did not change from the value before the test, while maintaining a high level in terms of durability.

On the other hand, compared to the examples, the C/N ratio of phototisfs using dyes having a henzointrenine skeleton, which is generally known to have high reflectance, The durability is poor because the value is lower than the value before the test.

Table 4 with margin below Reflectance C/N Sensitivity (%) (dB) (mW) Example 1 68 50 5.5 Example 2
67 50 5.5 Example 3 74 5
0 6.0 Example 4 72 50 6.
0 Example 5 73 51 6.0 Example 6
71 51 6.0 Example 7 76
50 6.0 Comparative Example 1 73 47 8
．． 0 Comparative Example 2 69 48 7.5 As is clear from Table 4, optical discs (Examples 8 to 14) having a recording layer made of a specific cyanine dye of the present invention and a reflective layer formed by RF sputtering ) has good sensitivity and C
/NL” also maintains a high level.The optical disc in which the above-mentioned reflective layer was formed by DC sputtering (Example 1)
~7), no decrease in sensitivity or C/N is observed. Therefore, it can be said that the dye recording layer has wide applicability to manufacturing conditions.

On the other hand, in the optical discs (Comparative Examples 3 and 4) using the conventional dye having a benzindolenine skeleton, in which the reflective layer was formed in the same way, the reflective layer was formed by DC sputtering, or in the case where the reflective layer was formed by DC sputtering, or Sensitivity, C/N
It can be seen that it is inferior in

Claims (1)

[Claims] 1. On the board, the following general formula (I a); ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ ( I a) and the following general formula ( I b); ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ ( I b ) [However, R^1, R^2 and R^3 each independently represent an alkyl group which may have a substituent having 1 to 8 carbon atoms, and Q is a hydrogen atom or represents an alkyl group, phenyl group or benzyl group which may have a substituent having 1 to 8 carbon atoms;
^p^- represents an anion, and p is 1 or 2
A recording layer on which information can be recorded by a laser is provided, the recording layer being made of at least one type of cyanine dye having an indolenine skeleton represented by the following: Furthermore, a reflective layer made of metal is provided on the recording layer. An information recording medium. 2. On the board, the following general formula ( I a); ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ ( I a) and the following general formula ( I b); ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ ( I b ) [However, R^1, R^2 and R^3 each independently represent an alkyl group which may have a substituent having 1 to 8 carbon atoms, and Q is a hydrogen atom or represents an alkyl group, phenyl group or benzyl group which may have a substituent having 1 to 8 carbon atoms;
^p^- represents an anion, and p is 1 or 2
] While rotating an information recording medium comprising a recording layer made of at least one cyanine dye having an indolenine skeleton represented by An optical information recording method that involves recording information by irradiating a laser onto a recording layer from the substrate side.