JPH07309069A - Optical recording medium and information recording / reproducing method - Google Patents

Abstract

(57) [Summary] [Structure] The recording layer has a wavelength of 6 with a trimethine cyanine dye.
An optical recording medium, which is a mixture of light absorbers having a maximum absorption wavelength of 30 nm or more and 900 nm or less, and the weight ratio of the light absorber is 0.1% or more and less than 20%. [Effect] The recording / reproducing wavelength which has been shifting in recent years is 630.
770-830, which enables high-sensitivity recording / reproduction with a red laser of ~ 690 nm and has been used conventionally.
It is possible to provide an optical recording medium capable of reproduction or recording / reproduction with a near infrared laser of nm.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention can reproduce or record / reproduce an optical recording medium, particularly a red laser having a wavelength of 630 to 690 nm and a near infrared laser having a wavelength of 770 to 830 nm. The present invention relates to an optical recording medium.

[0002]

2. Description of the Related Art As an optical recording medium having a reflective layer on a substrate, a recordable or recordable CD corresponding to a compact disc (hereinafter abbreviated as CD) standard (Orange Book standard)
(Hereinafter, abbreviated as CD-R) has been proposed [for example,
Nikkei Electronics No. 465, P.I. 107,1
See the January 23, 989 issue]. As shown in FIG. 1, this optical recording medium has a recording layer 2, a reflective layer 3, and a protective layer 4 formed in this order on a substrate 1. When the recording layer of this optical recording medium is irradiated with a laser beam such as a semiconductor laser with high power, the recording layer undergoes a physical or chemical change to record information in the form of pits. By irradiating the pits thus formed with a low-power laser beam and detecting the reflected light, the information of the pits can be reproduced. A near infrared semiconductor laser having a wavelength of 770 to 830 nm is generally used for recording / reproducing of such an optical recording medium. Recently, development of a semiconductor laser having a wavelength shorter than 770 nm has progressed, and a high-output red semiconductor laser having a wavelength of 680 nm has been put into practical use for recording and reproduction [eg, Nikkei Electronics, No. 592, P.I. 65,
See the October 11, 1993 issue].

A red semiconductor laser with a wavelength of 630 nm, which is shorter than 680 nm, has a low output, but is being put to practical use for reproduction. As described above, by shortening the wavelength of the recording / reproducing laser to reduce the beam spot, a high-density optical recording medium becomes possible. Large-capacity optical recording media capable of storing moving images have been developed by shortening the wavelength of semiconductor lasers and data compression technology [eg, Nikkei Electronics, No. 589, P.P. 55,
August 30, 1993]. Such a high-density optical recording medium can record a large amount of data such as a moving image and is expected to be used for a video CD and the like [eg,
Nikkei Electronics, No. 594, P.I. 169, 1
See the November 8, 993 issue].

Further, in Japanese Unexamined Patent Publication No. 2-278519, recording is performed with high sensitivity using a short wavelength laser of 680 nm.
High-sensitivity and high-speed recording has been proposed by a method of reproducing at 80 nm. However, although it is possible to reproduce at 780 nm, the reflectance at 680 nm is as small as 10% or less, and it was not easy to reproduce with a short wavelength laser of 680 nm. Therefore, in order to increase the density, it is desired that the recorded wavelength can be reproduced at 680 nm.

On the other hand, Japanese Patent Laid-Open No. 6-40162 proposes an optical recording medium capable of recording / reproducing with a short wavelength laser. This medium uses an indocarbocyanine dye in the recording layer. The maximum absorption wavelength of this dye is 600n
It is in the vicinity of m and can be recorded by using a 630 nm He / Ne laser, but it is 670 to 690 nm and 770.
It has almost no absorption at ~ 830 nm, and has a conventional wavelength of 770.
The sensitivity of the near infrared semiconductor laser of 830 nm or the red semiconductor laser of 670 to 690 nm which has been put into practical use is insufficient. Against this background, the recording / reproducing wavelength of the optical recording medium is changing to the wavelength range of the red semiconductor laser, which is 630 to 690 nm. Therefore, it is necessary to develop an optical recording medium corresponding to this, and the Orange Book that is compatible with conventional CD players, CD-ROM players and CD-R writers equipped with a near infrared semiconductor laser with a wavelength of 770 to 830 nm. There is a strong demand for an optical recording medium that satisfies the standards and is recordable or reproducible with the above-mentioned short wavelength laser of 630 to 680 nm.

[0006]

In the conventional CD-R, the organic dye used in the recording layer has a wavelength of 630 to 690 nm.
Since the absorption is large and the refractive index is small, the reflectance is as low as 10% or less, and the reproduced signal waveform after recording is distorted. Therefore, when a red laser having a wavelength of 630 to 680 nm is used, the conventional CD player or CD -It was found that reproduction is impossible with the signal processing technology used for ROM players and the like. In order to use such a conventional signal processing technique, the reflectance should be at least 15% or more, preferably 2% or more.
It is said that 0% or more is required. The purpose of the present invention is to
Reproduction or recording / reproduction is possible with a red laser selected from wavelengths 630 to 680 nm, and wavelengths 770 to 830.
Orange Book that can be played back or recorded with a near-infrared laser selected from nm (that is, a CD player, a CD-ROM player and a CD-R writer that have been commercially available in the past and are now popular all over the world). An object is to provide a compatible optical recording medium that satisfies the standard.

[0007]

The inventors of the present invention have made extensive studies to solve the above problems, and as a result, have come to propose the present invention. That is, this problem is solved by the following invention. (1) An optical recording medium having a recording layer, which comprises a trimethine cyanine dye and a wavelength of 630 nm or more 9
An optical recording medium, which is a mixture of light absorbers having a maximum absorption wavelength of 00 nm or less, and the weight ratio of the light absorbers is 0.1% or more and less than 20%. (2) A first light absorber having a maximum absorption wavelength in the wavelength range of 630 nm to less than 760 nm and a wavelength of 760 nm
In the item (1), which comprises a mixture of a second light absorbing agent having a maximum absorption wavelength of 900 nm or more and 900 nm or less, and the weight ratio of the first light absorbing agent and the second light absorbing agent is 1:99 to 99: 1. The optical recording medium described. (3) The trimethine cyanine dye forming the recording layer is
Item (1) which is a compound represented by the following formula (1)
Alternatively, the optical recording medium according to (2).

[0008]

[Chemical 5] [Wherein P is an atom group consisting of a substituted or unsubstituted 5-membered ring or 6-membered ring containing at least one nitrogen atom as represented by the following formulas (2) to (6)

[0009]

[Chemical 6] Q is an atomic group consisting of a substituted or unsubstituted 5-membered ring or 6-membered ring containing at least one nitrogen atom as represented by the following formulas (7) to (11)

[0010]

[Chemical 7] In the formulas (1) to (11), A and A ′ are atomic groups forming a benzene ring or a substituted benzene ring, or forming a naphthalene ring or a substituted naphthalene ring, and are the same or different. May be. R ₁ and R ₁ '
Is a substituted or unsubstituted alkyl group, an alkoxy group, an alkylhydroxy group, an aralkyl group, an alkenyl group, an alkylcarboxyl group, an alkylsulfonyl group, or an alkylcarboxyl group or an alkylsulfonyl group bonded to an alkali metal ion or an alkyl group. It can be different. R _{2 to} R ₈ are selected from a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group and a diphenylamino group, and R _{6 to} R ₈ may be a substituted or unsubstituted cyclic side chain having a plurality of carbon atoms. X is an anion selected from halogen atom, perchloric acid, borofluoric acid, benzenesulfonic acid, toluenesulfonic acid, alkylsulfonic acid, benzenecarboxylic acid, alkylcarboxylic acid or trifluoromethylcarboxylic acid, or a formula ( 12) to (18) represents an anion residue of the compound represented by [Chemical formula 8].

[0011]

[Chemical 8] (In the formulas (12) to (18), A and A ′ are atom groups forming a benzene ring or a substituted benzene ring, or forming a naphthalene ring or a substituted naphthalene ring, and are the same or different. R _{9 to} R ₃₁ are each a substituted or unsubstituted alkyl group, alkoxy group, hydroxy group, carboxyl group, halogen atom, allyl group, alkylcarboxyl group, alkylalkoxyl group, aralkyl group, alkylcarbonyl group, metal ion. Selected from a sulfonate alkyl group bonded to, a nitro group, an amino group, an alkylamino group, a phenyl group, a phenylethylene group, M is Ni, Co, Mn, Cu, Pd and P.
The transition metal selected from t is shown. M has an electric charge and may have a cation and a salt structure. a'represents the valence of an ionic body and is a positive integer including 0. Z represents a cation, a ′ = b ′ · c ′, and when a ′ = 0, b ′ · c ′ = 0 and Z does not exist, and the compound becomes a neutral body. In addition, when R ₁ and R ₁ ′ have a group to which an alkali metal ion is bonded, X may not be present. Y and Y'are selected from O, S, Se, NH, and -CH = CH-.
a is the number of moles and is represented by a positive integer determined by the charge number of X. (4) In an optical recording medium having a recording layer and a reflective layer formed on a substrate, the reflectance measured from the substrate side for light selected from a red laser having a wavelength of 630 to 690 nm is 15% or more, and The optical recording according to any one of items (1) to (3), wherein the reflectance measured from the substrate side with respect to light selected from a near infrared laser having a wavelength of 770 to 830 nm is 65% or more. Medium. (5) In an optical recording medium having a recording layer and a reflective layer formed on a substrate, the reflectance measured from the substrate side for light selected from a red laser having a wavelength of 630 to 690 nm is 20% or more. ) The optical recording medium according to [1]. (6) The optical recording medium according to any one of items (1) to (5), wherein a recording layer, a reflective layer, and a protective layer are provided in this order on a substrate.

(7) A recording layer and a reflective layer are formed on a substrate, and the recording layer contains a trimethine cyanine dye.
A mixture of light absorbers having a maximum absorption wavelength in the wavelength range of 630 nm to 900 nm, and the weight ratio of the light absorbers is
A method for recording / reproducing information by an optical recording medium having a content of 0.1% or more and less than 20%, wherein recording / reproducing is performed by a red laser selected from wavelengths 630 to 690 nm and wavelengths 770 to 770.
The information recording / reproducing method for an optical recording medium according to any one of items (1) to (6), wherein recording / reproducing is performed with a near infrared laser selected from 830 nm.

(8) A recording layer and a reflective layer are formed on a substrate, and the recording layer contains a trimethine cyanine dye.
A mixture of light absorbers having a maximum absorption wavelength in the wavelength range of 630 nm to 900 nm, and the weight ratio of the light absorbers is
A method for recording / reproducing information by an optical recording medium having a content of 0.1% or more and less than 20%, recording / reproducing with a near-infrared laser selected from wavelengths 770 to 830 nm, and selecting this from wavelengths 630 to 690 nm. The information recording / reproducing method for an optical recording medium according to any one of items (1) to (6), wherein the information is also reproduced by a red laser.

(9) A recording layer and a reflective layer are formed on a substrate, and the recording layer is a mixture of a trimethine cyanine dye and a light absorbing agent having a maximum absorption wavelength in the wavelength range of 630 nm to 900 nm. The weight ratio of the light absorber is
A method for recording / reproducing information by an optical recording medium having a content of 0.1% or more and less than 20%, wherein recording / reproducing is performed by a red laser selected from wavelengths of 630 to 690 nm, and
The information recording / reproducing method for an optical recording medium according to any one of items (1) to (6), wherein the information is also reproduced by a near infrared laser selected from 70 to 830 nm.

According to the present invention, by using a mixture of the above-mentioned trimethinecyanine dye and a light absorber in the recording layer, recording and reproduction can be performed with a red laser having a wavelength of 630 to 690 nm, and a wavelength of 770 can be used. Recordable and reproducible with a near-infrared laser of 830 nm and a wavelength of 77
A signal recorded by a near infrared laser of 0 to 830 nm can be reproduced by a red laser having a wavelength of 630 to 690 nm,
Further, it is possible to provide an optical recording medium compatible with two lasers having different wavelengths, which can reproduce a signal recorded by a red laser having a wavelength of 630 to 690nm by a near infrared laser having a wavelength of 770 to 830nm. Become.

A specific configuration of the present invention will be described in detail below. The optical recording medium of the present invention basically has a reflective layer on a substrate, as shown in FIG. The optical recording medium refers to both a read-only optical read-only medium in which information is recorded in advance and an optical recording medium in which information can be recorded and reproduced. However, here, as a suitable example, an optical recording medium capable of recording and reproducing the latter information,
Particularly, an optical recording medium in which a recording layer, a reflective layer and a protective layer are formed in this order on a substrate will be described. This optical recording medium has a four-layer structure as shown in FIG. That is, the recording layer 2 is formed on the substrate 1, the reflective layer 3 is provided in close contact therewith, and the protective layer 4 further covers the reflective layer 3 thereon.

The material of the substrate may basically be transparent at the wavelengths of the recording light and the reproducing light. For example, a polymer material such as a polycarbonate resin, a vinyl chloride resin, an acrylic resin such as polymethylmethacrylate, an amorphous polyolefin resin, a polystyrene resin, an epoxy resin, or an inorganic material such as glass is used. These substrate materials are formed into a disc-shaped substrate by an injection molding method or the like. If necessary, grooves or pits may be formed on the surface of the substrate.

A recording layer is formed on the substrate. Current,
For commercially available 770-830nm recording and reproducing devices,
A pentamethine cyanine dye having five methine groups is used in the recording layer (for example, JP-A-2-292747). In such a recording layer, there is a large absorption around 700 nm, and recording at 630 to 690 nm is possible,
We have found that due to the small refractive index at 630 to 690 nm and the large absorption, the reflectance is low, and the reproduction at 630 to 690 nm becomes very difficult and ends up.

On the other hand, in the present invention, a trimethine cyanine dye having three methine groups is used in the recording layer.
Trimethine cyanine dye has a λ _max of 500 to 600
Since it exists in nm and has a large refractive index at 630 to 690 nm and a small absorbance, a large reflectance can be obtained. or,
Since it has a large refractive index and a small absorption at 770 to 830 nm, it can be played back even on CD players, CD-ROM players and CD-R writers equipped with the 770 to 830 nm semiconductor lasers currently in use. We have found this.

Specifically, the trimethinecyanine dyes include indocarbocyanine dyes, thiacarbocyanine dyes, quinoxacarbocyanine dyes, quinocarbocyanine dyes, quinothiacarbocyanine dyes, serenacarbocyanine dyes, imida Examples thereof include carbocyanine dyes and oxacarbocyanine dyes which have a substituent in order to enhance solubility. These substituents may be singular or plural, but an alkyl group,
Alkoxy group, hydroxy group, carboxyl group, halogen atom, allyl group, alkylcarboxyl group, alkylalkoxyl group, aralkyl group, alkylcarbonyl group, sulfonate alkyl group bound to a metal ion, nitro group, amino group, alkylamino group, aryl Group, phenylethylene group and the like.

Among them, 1,3,3,1 ', 3', 3'-
Hexamethyl-2,2 '-(4,5,4', 5'-dibenzo) indocarbocyanine perchlorate, 3,3 '
-Diethyl-2,2 '-(6,7,6', 7'-dibenzo) thiacarbocyanine iodide, 3,3'-diethyl-2,2'-thiacarbocyanine iodide,
1,1'-diethyl-2,2'-quinocarbocyanine iodide, 3,3'-diethyl-2,2'-selenacarbocyanine iodide, 1,3'-diethyl-4,
2'-quinoxacarbocyanine iodide, 3,
3 ', 9-triethyl-2,2'-(4,5,4 ',
5'-dibenzo) thiacarbocyanine bromide, 1,
1'-Diethyl-2,4'-quinocarbocyanine iodide, 1,3'-diethyl-4,2'-quinothiacarbocyanine iodide and the like are preferable.

In the present invention, in order to improve the recording sensitivity with respect to 630 to 690 nm and 770 to 830 nm,
A light absorber having a maximum absorption wavelength of 30 nm or more and 900 nm or less is 0.1% or more and less than 20%, preferably 1% or more 1
It is desirable to mix them in a weight ratio of 0% or less. Here, the maximum absorption wavelength of the light absorber will be described. In the method for measuring the maximum absorption wavelength of a light absorber in the present invention, first, the light absorber is dissolved in an appropriate organic solvent, and a thin film is formed on a glass substrate having a thickness of about 1 mm by spin coating or the like.
The UV-visible absorption spectrum is measured using a commercially available spectrophotometer. The wavelength at which the absorbance is maximum is read from the measured spectrum, and that wavelength is used as the maximum absorption wavelength.

According to JP-A-3-281287, by using a mixture of a pentamethine cyanine dye and a trimethine cyanine dye (pentamethine cyanine dye: trimethine cyanine dye = 20: 80 to 95: 5) in the recording layer. An optical recording medium having high reflectivity and high durability has been proposed. However, at this mixing ratio, the amount of pentamethinecyanine dye is too much, the absorption at the wavelength of 630 to 690 nm, which is the oscillation wavelength of the red semiconductor laser, becomes large, and the refractive index becomes small, so that a reflectance of 15% or more cannot be obtained. We have found that this may occur and may not be playable on players equipped with a red semiconductor laser.

As the light absorber in the present invention, pentamethine cyanine dye, phthalocyanine dye, naphthalocyanine dye, porphyrin dye, azo dye,
Squarylium dye, pyrylium dye, thiopyrylium dye, azurenium dye, naphthoquinone dye, anthraquinone dye, indophenol dye,
There are triphenylmethane dyes, xanthene dyes, indanthrene dyes, indigo dyes, thioindigo dyes, merocyanine dyes, thiazine dyes, acridine dyes, oxazine dyes, etc.
Any material having a maximum absorption wavelength of 30 nm or more and 900 nm or less and capable of being mixed with the trimethine cyanine dye may be used.

Among them, 1,3,3,1 ', 3', 3'-
Hexamethyl-2,2 '-(4,5,4', 5'-dibenzo) indodicarbocyanine perchlorate, 3,
3'-diethyl-2,2 '-(6,7,6', 7'-dibenzo) thiadicarbocyanine iodide, 3,3 '
-Diethyl-2,2'-thiadicarbocyanine iodide, 1,1'-diethyl-2,2'-quinodicarbocyanine iodide, 3,3'-diethyl-2,2'-
Serenadicarbocyanine iodide, 1,3'-diethyl-4,2'-quinoxadicarbocyanine iodide, 3,3 ', 9-triethyl-2,2'-(4
5,4 ', 5'-dibenzo) thiadicarbocyanine bromide, 1,1'-diethyl-2,4'-quinodicarbocyanine iodide, 1,3'-diethyl-4,2'
-Quinothiadicarbocyanine iodide and the like are preferred.

The light absorber has a wavelength of 630 to 690n.
In order to impart recording sensitivity to the red laser of m, in order to impart recording sensitivity to the first light absorber having a maximum absorption wavelength in the wavelength range of 630 nm to less than 760 nm and the near infrared laser wavelength of 770 to 830 nm, Wavelength 760nm or more 9
A mixture of second light absorbers having a maximum absorption wavelength below 00 nm may be used. At this time, the weight ratio of the first light absorbing agent to the second light absorbing agent is 1:99 to 99: 1, preferably 25: 7.
Mix so as to be 5 to 75:25.

When the weight ratio of the first light absorbing agent to the second light absorbing agent is less than 1%, the recording sensitivity for the red laser having a wavelength of 630 to 690 nm is lowered, and in the worst case, recording may be impossible. On the contrary, if the weight ratio of the first light absorbing agent to the second light absorbing agent exceeds 99%, the wavelength of 770 to 830
The recording sensitivity to the near-infrared laser of nm decreases, and in the worst case, recording may be impossible.

As the first light absorbing agent, pentamethine cyanine dye, phthalocyanine dye, naphthalocyanine dye, porphyrin dye, azo dye, squarylium dye, pyrylium dye, thiopyrylium dye, azurenium dye, Naphthoquinone dye, anthraquinone dye, indophenol dye, triphenylmethane dye, xanthene dye, indanthrene dye, indigo dye, thioindigo dye, merocyanine dye, thiazine dye, acridine dye, oxazine There are dyes, but in short, wavelength 630nm
Any material having a maximum absorption wavelength of less than 760 nm and capable of being mixed with the trimethine cyanine dye may be used.

Among them, 1,3,3,1 ', 3', 3'-
Hexamethyl-2,2 '-(4,5,4', 5'-dibenzo) indodicarbocyanine perchlorate, 3,
3'-diethyl-2,2 '-(6,7,6', 7'-dibenzo) thiadicarbocyanine iodide, 3,3 '
-Diethyl-2,2'-thiadicarbocyanine iodide, 3,3'-diethyl-2,2'-thiatricarbocyanine bromide, 1,1'-diethyl-2,2'-
Quinodicarbocyanine iodide, 3,3′-diethyl-2,2′-selena dicarbocyanine iodide,
1,3'-diethyl-4,2'-quinoxadicarbocyanine iodide, 3,3 ', 9-triethyl-2,
2 '-(4,5,4', 5'-dibenzo) thiadicarbocyanine bromide, 1,1'-diethyl-2,4'-
Quinodicarbocyanine iodide, 1,3′-diethyl-4,2′-quinothiadicarbocyanine iodide and the like are preferable.

As the second light absorber, heptamethine cyanine dye, phthalocyanine dye, naphthalocyanine dye, porphyrin dye, azo dye, squarylium dye, pyrylium dye, thiopyrylium dye, azurenium dye, Naphthoquinone dye, anthraquinone dye, indophenol dye, triphenylmethane dye, xanthene dye, indanthrene dye, indigo dye, thioindigo dye, merocyanine dye, thiazine dye, acridine dye, oxazine There are dyes, but 760nm or more and 900nm
The following may be used as long as they have the maximum absorption wavelength and can be mixed with the trimethine cyanine dye. Of these, the heptamethine cyanine dye is suitable because it has a maximum absorption wavelength near 800 nm and is easily mixed with the trimethine cyanine dye.

Among them, 1,3,3,1 ', 3', 3'-
Hexamethyl-2,2 '-(4,5,4', 5'-dibenzo) indotricarbocyanine perchlorate, 3,
3'-diethyl-2,2 '-(6,7,6', 7'-dibenzo) thiatricarbocyanine iodide, 3,
3'-diethyl-2,2'-thiatricarbocyanine iodide, 1,1'-diethyl-2,2'-quinotricarbocyanine iodide, 3,3'-diethyl-
2,2'-selena tricarbocyanine iodide,
1,3'-diethyl-4,2'-quinoxatricarbocyanine iodide, 3,3 ', 9-triethyl-
2,2 '-(4,5,4', 5'-dibenzo) thiatricarbocyanine bromide, 1,1'-diethyl-2,
4'-quinotricarbocyanine iodide, 1,3 '
-Diethyl-4,2'-quinothiatricarbocyanine iodide and the like are suitable. If necessary, additives such as a quencher and an ultraviolet absorber can be mixed or introduced as a substituent into the mixed dye. For example, examples of the additive include those represented by the following formulas (12) to (18) (chemical formula 9).

[0032]

[Chemical 9] (However, A and A ′ are an atomic group forming a benzene ring or a substituted benzene ring or forming a naphthalene ring or a substituted naphthalene ring, and may be the same or different. May be singular or plural, but is an alkyl group, an alkoxy group, a hydroxy group, a carboxyl group, a halogen atom, an allyl group, an alkylcarboxyl group, an alkylalkoxyl group, an aralkyl group, an alkylcarbonyl group, a metal ion. And a sulfonate alkyl group, a nitro group, an amino group, an alkylamino group, a phenyl group, a phenylethylene group, etc. R _{9 to} R ₃₁ are substituted or unsubstituted alkyl groups, alkoxy groups, hydroxy groups, carboxyl groups,
Examples thereof include a halogen atom, an allyl group, an alkylcarboxyl group, an alkylalkoxyl group, an aralkyl group, an alkylcarbonyl group, a sulfonate alkyl group bonded to a metal ion, a nitro group, an amino group, an alkylamino group, a phenyl group and a phenylethylene group. M is Ni, Co, M
Transition metals such as n, Cu, Pd and Pt are shown.
M has an electric charge and may have a cation and a salt structure.
a'represents the valence of an ionic body and is a positive integer including 0. Z represents a cation, a ′ = b ′ · c ′,
When a ′ = 0, b ′ · c ′ = 0 and Z does not exist, and the compound becomes a neutral body. These dyes have a thickness of 50 to 500 nm, preferably 100 to 500 nm on a substrate by a coating method such as a spin coating method or a casting method, a sputtering method, a chemical vapor deposition method, or a vacuum vapor deposition method.
A 200 nm recording layer is formed. Particularly in the coating method, a coating solvent in which a dye is dissolved or dispersed is used, and it is preferable to select a solvent that does not damage the substrate. For example, an alcohol solvent such as methanol,
Aliphatic hydrocarbon solvents such as hexane and octane, cyclic hydrocarbon solvents such as cyclohexane, aromatic hydrocarbon solvents such as benzene, halogenated hydrocarbon solvents such as chloroform, ether solvents such as dioxane, methyl cellosolve Cellosolve-based solvents such as, ketone-based solvents such as acetone, ester-based solvents such as ethyl acetate, etc. are used alone or in combination. Further, the recording layer is not limited to one layer, and a plurality of dyes may be formed in multiple layers, or the dyes may be dispersed in a polymer thin film or the like, preferably about 50% or more. If a solvent that does not damage the substrate cannot be selected, sputtering, chemical vapor deposition, vacuum vapor deposition, etc. are effective.

Next, on the recording layer, a thickness of 50 to 300 nm,
A reflective layer having a thickness of 70 to 150 nm is preferably formed. The material of the reflective layer has a sufficiently high reflectance at the wavelength of the reproduction light, for example, Au, Al, Ag, Cu, Ti, Cr, N.
Metals of i, Pt, Ta, Cr and Pd can be used alone or as an alloy. Among these, Au and Al have a high reflectance and are suitable as a material for the reflective layer. Other than the above, the following may be included. For example, M
g, Se, Hf, V, Nb, Ru, W, Mn, Re, F
e, Co, Rh, Ir, Cu, Zn, Cd, Ga, I
Metals and semimetals such as n, Si, Ge, Te, Pb, Po, Sn and Bi can be mentioned. Further, a material containing Au as a main component is preferable because a reflective layer having a high reflectance can be easily obtained. Here, the main component means that the content rate is 50% or more. A low refractive index thin film and a high refractive index thin film are alternately stacked with a material other than metal to form a multilayer film,
It can also be used as a reflective layer.

In the present invention, examples of the method for forming the reflective layer include a sputtering method, a chemical vapor deposition method and a vacuum vapor deposition method. Further, an intermediate layer such as a reflection amplification layer or an adhesive layer may be provided between the recording layer and the reflective layer in order to increase the reflectance and improve the adhesion. The material used for the intermediate layer preferably has a large refractive index at the wavelength of the reproduction light, and may be an inorganic material or an organic material. For example, as the inorganic material, Si ₃ N ₄ , AlN, Zn
S, a mixture of ZnS and SiO ₂ , SiO ₂ , TiO ₂ ,
There are CeO ₂ , Al ₂ O _{3 and the} like, and these materials may be used alone or in combination of two or more. On the other hand, as organic materials, cyanine dyes, phthalocyanine dyes, naphthalocyanine dyes, porphyrin dyes, azo dyes, squarylium dyes, pyrylium dyes, thiopyrylium dyes, azurenium dyes, naphthoquinone dyes, anthraquinone dyes Dyes, indophenol dyes, triphenylmethane dyes, xanthene dyes, indanthrene dyes, indigo dyes, thioindigo dyes, merocyanine dyes, thiazine dyes, acridine dyes, oxazine dyes, etc. Polystyrene, polyvinyl acetate, polycarbonate, polyethylene, polypropylene, polyacrylic acid ester, polymethacrylic acid ester, styrene-acrylonitrile copolymer, polyvinyl alcohol, polyvinyl acetal,
Polymer compounds such as polyvinyl butyral, polyvinyl formal, and polyvinyl pyrrolidone can be mentioned.

The optical recording medium of the present invention thus obtained is
A medium having a recording layer and a reflective layer formed on a substrate,
The reflectance from the substrate side to the light having a wavelength selected from the range of ˜690 nm is 15% or more, preferably 25% or more, and the reflection from the substrate side to the light having the wavelength selected from the range of 770 nm to 830 nm. It has a reflectance of 65% or more and satisfies the reflectance of the Orange Book (CD-R) standard. If these standards are satisfied, it can be satisfactorily played back on a large number of CD players that have been commercially available in the past.

A protective layer may be further formed on the reflective layer. The material of the protective layer is not particularly limited as long as it protects the reflective layer from external force, and may be an organic substance or an inorganic substance. Examples of the organic substance include a thermoplastic resin, a thermosetting resin, a UV curable resin, and the like. UV curable resins are preferred. Examples of the inorganic substance include SiO ₂ , SiN ₄ , MgF ₂ , SnO _{2 and the} like. A thermoplastic resin, a thermosetting resin, etc. can be formed by dissolving in a suitable solvent, applying a coating solution, and drying. The UV curable resin can be formed as it is or by dissolving it in a suitable solvent to prepare a coating solution, applying the coating solution, and irradiating with UV light to cure the coating solution. Examples of the UV curable resin include urethane acrylate, epoxy acrylate,
An acrylate resin such as polyester acrylate can be used. These materials may be used alone or as a mixture, and may be used not only as a single layer but also as a multilayer film. As the method of forming the protective layer, a coating method such as a spin coating method or a casting method, a sputtering method, a chemical vapor deposition method, or the like is used as in the recording layer, and the spin coating method is preferable among them.

The red laser used in the present invention is 630 to 630.
Any laser having a wavelength of 690 nm may be used. For example, there are dye lasers that can select wavelengths in a wide range of the visible region, helium neon lasers with a wavelength of 633 nm, high-power semiconductor lasers with a wavelength of 680 nm and semiconductor lasers with a wavelength of 635 nm that have been recently developed. Considering this, a semiconductor laser is suitable. Further, the near infrared laser may be any laser as long as it has a wavelength of 770 to 830 nm, but commercially available CD and CD-R
Semiconductor lasers used in OM players and CD-R recorders are suitable. Hereinafter, an example of an embodiment of the present invention will be described with reference to examples.

[0038]

【Example】

[Example 1] Trimethine cyanine dye NK3239
(1,3,3,1 ', 3', 3'-hexamethyl-2,
2 '-(4,5,4', 5'-dibenzo) indocarbocyanine perchlorate) [manufactured by Japan Photosensitive Dye Research Institute]
0.2g and pentamethine cyanine dye NK2929
(1,3,3,1 ', 3', 3'-hexamethyl-2,
2 '-(4,5,4', 5'-dibenzo) indodicarbocyanine perchlorate) [manufactured by Japan Photosensitive Dye Research Institute]
0.01 g of 2,2,3,3-tetrafluoro-1-
Dissolve in 10 ml of propanol (Tokyo Kasei) to prepare a dye solution. As the substrate, a disc-shaped substrate made of polycarbonate resin having a continuous guide groove (track pitch: 1.6 μm) with a diameter of 120 mmφ and a thickness of 1.2 mm was used. Dye solution is spin-coated on this substrate and 70 ° C 2
After drying for an hour, a recording layer having a thickness of 150 nm was formed. On this recording layer, a Balzers sputtering device (C
Au was sputtered using DI-900) to form a reflective layer having a thickness of 100 nm. Argon gas was used as the sputtering gas. The sputtering conditions were sputtering power of 2.5 kW and sputtering gas pressure of 1.0 × 10 ^-2 Torr. Further, after UV-curing resin SD-17 (manufactured by Dainippon Ink and Chemicals, Inc.) was spin-coated on the reflective layer, it was irradiated with ultraviolet rays to have a thickness of 6 μm.
To form a protective layer. The medium thus prepared is 680
nm optical disk evaluation device DDU-1000 and KEN with red semiconductor laser head
Linear velocity of 2.8m using WOOD CD encoder
/ S, laser power was recorded at 8 mW. After recording, the signal was reproduced using the same evaluation device, and the reflectance and error rate were measured. In addition, the recorded sample has a reproduction wavelength of 7
The reproduction was evaluated by an optical disk evaluation device manufactured by Pulstec Industrial Co., Ltd. equipped with an 80 nm near-infrared semiconductor laser head. On the other hand, an optical disk evaluation device DDU-100 manufactured by Pulstec Industrial Co., Ltd. equipped with a 780 nm near infrared semiconductor laser head
Recording was performed at a linear velocity of 2.8 m / s and a laser power of 10 mW using a 0 and KENWOOD CD encoder. After recording, reproduction was evaluated with a commercially available CD player having a reproduction wavelength of 780 nm. In addition, this recorded sample
Evaluation was carried out using an optical disk evaluation device DDU-1000 manufactured by Pulstec Industrial Co., Ltd. equipped with a 0 nm red semiconductor laser head. Furthermore, this recorded sample was measured at a wavelength of 635n.
m An optical disk evaluation device DDU-1000 manufactured by Pulstec Industrial Co., which is equipped with a red semiconductor laser head, was used for evaluation. To measure the maximum absorption wavelength of the pentamethine cyanine dye NK2929, 0.1 g of NK2929 was added to 2,2,3,3-tetrafluoro-1-propanol 1
The dye solution was dissolved in 0 ml to prepare a dye solution, the dye solution was spin-coated on a glass substrate, and dried at 70 ° C. for 2 hours to form a dye thin film having a thickness of 100 nm. The absorption spectrum was measured using a UV-visible spectrophotometer UV-2200 manufactured by Shimadzu Corporation, and the wavelength at which the absorbance was maximum was determined.

[Example 2] In Example 1, the trimethine cyanine dye NK3239 (1, 3, 3, 1 ',
3 ', 3'-hexamethyl-2,2'-(4,5,
0.2 g of 4 ', 5'-dibenzo) indocarbocyanine perchlorate) (manufactured by Japan Photosensitive Dye Research Institute) and pentamethine cyanine dye NK2929 (1,3,3,1',
3 ', 3'-hexamethyl-2,2'-(4,5,
4 ', 5'-dibenzo) indodicarbocyanine perchlorate) [manufactured by Japan Photosensitive Dye Research Institute] 0.046 g,
A medium was prepared in the same manner except that the dye solution was dissolved in 10 ml of 2,2,3,3-tetrafluoro-1-propanol (Tokyo Kasei). The produced medium was evaluated for reflectance and error rate in the same manner as in Example 1.

Example 3 Trimethine Cyanine Dye NK
3239 (1,3,3,1 ', 3', 3'-hexamethyl-2,2 '-(4,5,4', 5'-dibenzo) indocarbocyanine perchlorate) [manufactured by Japan Photosensitive Dye Research Institute ] 0.2 g and pentamethine cyanine dye NK29
29 (1,3,3,1 ', 3', 3'-hexamethyl-
2,2 '-(4,5,4', 5'-dibenzo) indodicarbocyanine perchlorate) [manufactured by Japan Photosensitive Dye Research Institute] 0.01 g, and heptamethine cyanine dye NK20
14 (1,3,3,1 ', 3', 3'-hexamethyl-
2,2 '-(4,5,4', 5'-dibenzo) -indotricarbocyanine perchlorate) [manufactured by Japan Photosensitive Dye Research Institute] was added to 0.01 g of 2,2,3,3-tetrafluoro- Dissolve 1-propanol (Tokyo Kasei) in 10 ml to prepare a dye solution. The substrate is made of polycarbonate resin and has continuous guide grooves (track pitch: 1.6 μm)
A disc-shaped member having a diameter of 120 mmφ and a thickness of 1.2 mm was used. A dye solution was spin-coated on this substrate and dried at 70 ° C. for 2 hours to form a recording layer having a thickness of 150 nm. Au was sputtered on the recording layer using a Balzers sputtering device (CDI-900) to form a reflective layer having a thickness of 100 nm. Argon gas was used as the sputtering gas. The sputtering conditions were sputtering power of 2.5 kW and sputtering gas pressure of 1.0 × 10 ^-2 Torr. Further, an ultraviolet curable resin SD-17 (manufactured by Dainippon Ink and Chemicals, Inc.) was spin-coated on the reflective layer and then irradiated with ultraviolet rays to form a protective layer having a thickness of 6 μm. The produced medium is used in Example 1.
The reflectance and the error rate were evaluated in the same manner as in. The maximum absorption wavelength of the heptamethine cyanine dye NK2014 was measured by the same method as in Example 1.

[Example 4] In Example 1, the trimethine cyanine dye NK467 (3,3'-diethyl-2,
2 '-(6,7,6', 7'-dibenzo) thiacarbocyanine iodide) [manufactured by Japan Photosensitive Dye Research Institute] 0.2
g, and pentamethine cyanine dye NK2627 (3,
0.01 g of 3'-diethyl-2,2 '-(6,7,6', 7'-dibenzo) thiadicarbocyanine iodide) (manufactured by Japan Photosensitive Dye Research Institute) and heptamethine cyanine dye NK2014 (1 , 3,3,1 ', 3', 3'-hexamethyl-2,2 '-(4,5,4', 5'-dibenzo) -indotricarbocyanine perchlorate) (manufactured by Japan Photosensitive Dye Research Institute) 0.01 g to 2,2,3,3-
Tetrafluoro-1-propanol (Tokyo Kasei) 10
An optical recording medium was prepared in the same manner except that the dye solution was dissolved in ml to prepare a dye solution. The produced medium was evaluated for reflectance and error rate in the same manner as in Example 1. The maximum absorption wavelength of the pentamethine cyanine dye NK2627 was measured by the same method as in Example 1.

Example 5 In Example 1, the trimethine cyanine dye NK3 (1,1′-diethyl-2,2 ′)
-Quinocarbocyanine iodide) [manufactured by Japan Photosensitive Dye Research Institute] 0.2 g, and pentamethine cyanine dye NK1
456 (1,1'-diethyl-2,2'-quinodicarbocyanine iodide) [manufactured by Japan Photosensitive Dye Research Institute] 0.
01g and heptamethine cyanine dye NK2014
(1,3,3,1 ', 3', 3'-hexamethyl-2,
2 '-(4,5,4', 5'-dibenzo) -indotricarbocyanine perchlorate) [manufactured by Japan Photosensitive Dye Research Institute], 0.01 g of 2,2,3,3-tetrafluoro-
An optical recording medium was prepared in the same manner except that the dye solution was dissolved in 10 ml of 1-propanol (Tokyo Kasei). The produced medium was evaluated for reflectance and error rate in the same manner as in Example 1. In addition, pentamethine cyanine dye N
The maximum absorption wavelength of K1456 was measured in the same manner as in Example 1.

Example 6 In Example 1, the trimethine cyanine dye NK3239 (1, 3, 3, 1 ',
3 ', 3'-hexamethyl-2,2'-(4,5,
0.2 g of 4 ', 5'-dibenzo) indocarbocyanine perchlorate) (manufactured by Japan Photosensitive Dye Research Institute) and pentamethine cyanine dye NK1456 (1,1'-diethyl-2,2'-quinodicarbocyanine aio). Dyad) [manufactured by Japan Photosensitive Dye Research Institute] 0.025 g and heptamethine cyanine dye NK1666 (3,3′-diethyl-2,
0.01 g of 2'-thiatricarbocyanine bromide) (manufactured by Japan Photosensitive Dye Research Institute) is dissolved in 10 ml of 2,2,3,3-tetrafluoro-1-propanol (Tokyo Kasei) to prepare a dye solution. An optical recording medium was prepared in the same manner except that the above was performed. The produced medium was evaluated for reflectance and error rate in the same manner as in Example 1. The maximum absorption wavelength of the heptamethine cyanine dye NK1666 was also measured by the same method as in Example 1.

Example 7 In Example 1, the trimethine cyanine dye NK3 (1,1′-diethyl-2,2 ′)
-Quinocarbocyanine iodide) [manufactured by Japan Photosensitive Dye Research Institute] 0.2 g, and pentamethine cyanine dye NK2
627 (3,3'-diethyl-2,2 '-(6,7,
6 ', 7'-dibenzo) thiadicarbocyanine iodide) (manufactured by Japan Photosensitive Dye Research Institute) and 0.01 g of heptamethine cyanine dye NK1666 (3,3'-diethyl-2,2'-thiatricarbocyanine Bromide) [manufactured by Japan Photosensitive Dye Research Institute] 0.025 g, 2, 2, 3, 3
-Tetrafluoro-1-propanol (Tokyo Kasei) 1
An optical recording medium was prepared in the same manner except that it was dissolved in 0 ml to prepare a dye solution. The produced medium was evaluated for reflectance and error rate in the same manner as in Example 1.

COMPARATIVE EXAMPLE 1 In Example 1, the trimethine cyanine dye NK3239 (1, 3, 3, 3) was used as the dye.
1 ', 3', 3'-hexamethyl-2,2 '-(4
An optical recording medium was prepared in the same manner except that only 5,4 ′, 5′-dibenzo) indocarbocyanine perchlorate) (manufactured by Japan Photosensitive Dye Research Institute) was used. The produced medium was evaluated for reflectance and error rate in the same manner as in Example 1.

Comparative Example 2 In Example 1, the trimethine cyanine dye NK3239 (1, 3, 3, 1 ',
3 ', 3'-hexamethyl-2,2'-(4,5,
4 ', 5'-dibenzo) indocarbocyanine perchlorate) [manufactured by Japan Photosensitive Dye Research Institute] and 0.14 g of pentamethinecyanine dye NK2929 (1,3,3,3)
1 ', 3', 3'-hexamethyl-2,2 '-(4
5,4 ', 5'-dibenzo) indodicarbocyanine perchlorate) [manufactured by Japan Photosensitive Dye Research Institute] 0.06 g
Was dissolved in 10 ml of 2,2,3,3-tetrafluoro-1-propanol (Tokyo Kasei Co., Ltd.) to prepare a dye solution, whereby the mixing ratio of the pentamethinecyanine dye to the trimethinecyanine dye was 5% to 30%. An optical recording medium was prepared in the same manner except that the content was increased to%. The characteristics of the manufactured medium were evaluated in the same manner as in Example 1.

Comparative Example 3 In Example 1, the trimethine cyanine dye NK3239 (1, 3, 3, 1 ',
3 ', 3'-hexamethyl-2,2'-(4,5,
4 ', 5'-dibenzo) indocarbocyanine perchlorate) [manufactured by Japan Photosensitive Dye Research Institute] and 0.1 g of heptamethine cyanine dye NK2014 (1,3,3,1',
3 ', 3'-hexamethyl-2,2'-(4,5,
4 ', 5'-dibenzo) -indotricarbocyanine perchlorate) [manufactured by Japan Photosensitive Dye Research Institute] 0.1 g,
An optical recording medium was produced in the same manner except that the dye solution was dissolved in 10 ml of 2,2,3,3-tetrafluoro-1-propanol (Tokyo Kasei). The characteristics of the manufactured medium were evaluated in the same manner as in Example 1. These results are summarized in Table 1.

[0048]

[Table 1] As is apparent from Table 1, the optical recording medium having the recording layer having the specific mixing weight ratio of the trimethine cyanine dye and the light absorber of the example has an extremely high reflectance at each laser wavelength and an error rate. It is shown that the optical recording medium of the comparative example has a low reflectance as compared with the examples, and the error rate is very high.

[0049]

According to the present invention, by using a mixture of a trimethine cyanine dye and a light absorber as a recording layer, the recording / reproducing wavelength which has been shifting in recent years is 630 to 690.
It is possible to record / reproduce with a red laser of nm, and record / reproduce with a near-infrared laser of 770 to 830 nm which has been conventionally used for CD and CD-ROM players and CD-R recorders. Wavelength 770
The signal recorded by the 830 nm near-infrared laser has a wavelength of 6
To provide an optical recording medium which can be reproduced by a red laser having a wavelength of 30 to 690 nm and, conversely, a signal recorded by a red laser having a wavelength of 630 to 690 nm can be reproduced by a near infrared laser having a wavelength of 770 to 830 nm. Is possible.

[Brief description of drawings]

FIG. 1 is a structural sectional view of an optical recording medium.

[Explanation of symbols]

 1 substrate 2 recording layer 3 reflective layer 4 protective layer

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Sumio Hirose 1190 Kasama-cho, Sakae-ku, Yokohama-shi, Kanagawa Mitsui Toatsu Chemical Co., Ltd.

Claims (9)

[Claims] 1. An optical recording medium having a recording layer, wherein the recording layer contains a trimethine cyanine dye and a wavelength of 630 nm.
A mixture of light absorbers having a maximum absorption wavelength in the range of 900 nm to 900 nm, and the weight ratio of the light absorber is 0.1% to 20%.
An optical recording medium that is less than. 2. A light absorber having a wavelength of 630 nm or more and 760 n or more.
a first light absorber having a maximum absorption wavelength of less than m, and a wavelength of 76
A mixture of a second light absorber having a maximum absorption wavelength of 0 nm or more and 900 nm or less, and the weight ratio of the first light absorber and the second light absorber is 1:99 to 99: 1. The optical recording medium described. 3. The optical recording medium according to claim 1, wherein the trimethine cyanine dye forming the recording layer is a compound represented by the following formula (1) [Chemical formula 1]. [Chemical 1] [Wherein P is an atom group consisting of a substituted or unsubstituted 5-membered ring or 6-membered ring containing at least one nitrogen atom as represented by the following formulas (2) to (6) [Chemical Formula 2], [Chemical 2] Q is an atom group consisting of a substituted or unsubstituted 5-membered ring or 6-membered ring containing at least one nitrogen atom as represented by the following formulas (7) to (11) [Chemical Formula 3]: ] In the formulas (1) to (11), A and A ′ are atomic groups forming a benzene ring or a substituted benzene ring, or forming a naphthalene ring or a substituted naphthalene ring, and are the same or different. May be. R ₁ and R ₁ '
Is a substituted or unsubstituted alkyl group, an alkoxy group, an alkylhydroxy group, an aralkyl group, an alkenyl group, an alkylcarboxyl group, an alkylsulfonyl group, or an alkylcarboxyl group or an alkylsulfonyl group bonded to an alkali metal ion or an alkyl group. It can be different. R _{2 to} R ₈ are selected from a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group and a diphenylamino group, and R _{6 to} R ₈ may be a substituted or unsubstituted cyclic side chain having a plurality of carbon atoms. X is an anion selected from halogen atom, perchloric acid, borofluoric acid, benzenesulfonic acid, toluenesulfonic acid, alkylsulfonic acid, benzenecarboxylic acid, alkylcarboxylic acid or trifluoromethylcarboxylic acid, or a formula ( 12) to (18) represents an anion residue of the compound shown in [Chemical Formula 4]. [Chemical 4] (In the formulas (12) to (18), A and A ′ are atom groups forming a benzene ring or a substituted benzene ring, or forming a naphthalene ring or a substituted naphthalene ring, and are the same or different. R _{9 to} R ₃₁ are each a substituted or unsubstituted alkyl group, alkoxy group, hydroxy group, carboxyl group, halogen atom, allyl group, alkylcarboxyl group, alkylalkoxyl group, aralkyl group, alkylcarbonyl group, metal ion. Selected from a sulfonate alkyl group bonded to, a nitro group, an amino group, an alkylamino group, a phenyl group, a phenylethylene group, M is Ni, Co, Mn, Cu, Pd and P.
The transition metal selected from t is shown. M has an electric charge and may have a cation and a salt structure. a'represents the valence of an ionic body and is a positive integer including 0. Z represents a cation, a ′ = b ′ · c ′, and when a ′ = 0, b ′ · c ′ = 0 and Z does not exist, and the compound becomes a neutral body. In addition, when R ₁ and R ₁ ′ have a group to which an alkali metal ion is bonded, X may not be present. Y and Y'are selected from O, S, Se, NH, and -CH = CH-.
a is the number of moles and is represented by a positive integer determined by the charge number of X. ] 4. In an optical recording medium having a recording layer and a reflective layer formed on a substrate, the reflectance measured from the substrate side for light selected from a red laser having a wavelength of 630 to 690 nm is 15% or more, And wavelength 770-830
The optical recording medium according to any one of claims 1 to 3, wherein the reflectance measured from the substrate side with respect to light selected from a near-infrared laser having a wavelength of 65 nm is 65% or more. 5. An optical recording medium having a recording layer and a reflective layer formed on a substrate, wherein the reflectance measured from the substrate side for light selected from a red laser having a wavelength of 630 to 690 nm is 20% or more. Item 5. The optical recording medium according to item 4. 6. The optical recording medium according to claim 1, wherein a recording layer, a reflective layer and a protective layer are provided in this order on a substrate. 7. A recording layer and a reflective layer are formed on a substrate, and the recording layer comprises a trimethine cyanine dye and a wavelength of 6
It is a mixture of light absorbers having a maximum absorption wavelength of 30 nm or more and 900 nm or less, and the weight ratio of the light absorber is 0.1.
% Or more and less than 20%, an information recording / reproducing method using an optical recording medium, wherein recording / reproducing is performed with a red laser selected from wavelengths 630 to 690 nm, and wavelengths 770 to 830.
The information recording / reproducing method for an optical recording medium according to any one of claims 1 to 6, wherein the recording / reproducing is performed by a near infrared laser selected from nm. 8. A recording layer and a reflective layer are formed on a substrate, and the recording layer comprises a trimethine cyanine dye and a wavelength of 6
It is a mixture of light absorbers having a maximum absorption wavelength of 30 nm or more and 900 nm or less, and the weight ratio of the light absorber is 0.1.
% Or more and less than 20%, an information recording / reproducing method by an optical recording medium, wherein recording / reproducing is performed by a near infrared laser selected from wavelengths 770 to 830 nm, and the wavelength is 630
The information recording / reproducing method for an optical recording medium according to any one of claims 1 to 6, wherein the reproduction is performed with a red laser selected from ˜690 nm. 9. A recording layer and a reflective layer are formed on a substrate, and the recording layer comprises a trimethine cyanine dye and a wavelength of 63.
A mixture of light absorbers having a maximum absorption wavelength of 0 nm or more and 900 nm or less, and the weight ratio of the light absorbers is 0.1%.
A method of recording / reproducing information by an optical recording medium having a wavelength of 720 to 8%, the recording / reproducing method using a red laser selected from wavelengths of 630 to 690 nm.
The information recording / reproducing method for an optical recording medium according to any one of claims 1 to 6, wherein the information is also reproduced by a near infrared laser selected from 30 nm.