JPH03203694A - Optical recording medium - Google Patents

Abstract

PURPOSE:To enhance light resistance, by using a light-absorbing coloring matter which has a long absorption wavelength and contains an additive such as an azo coloring matter or the like having an absorption wavelength sorter than that of the light-absorbing coloring matter. CONSTITUTION:An optical recording medium comprises a base 2, a recording layer 3 thereon comprising a coloring matter, and a reflective layer 4 provided in close contact with the recording layer 3. Preferably, the medium further comprises a protective layer 5. The recording layer comprises a light absorbing coloring matter, which has an absorption maximum at 600-900 nm, and is preferably one or more of such coloring matters as cyanine, phthalocyanine, naphthalocyanine, anthraquinone, azo, triphenylmethane, pyrylium or pyrylium salt, and metal complex coloring matters. The light-absorbing coloring matter or a combination of the light-absorbing coloring matter and a quencher is mixed with a coloring matter having an absorption maximum at 350-600 nm. For use as the photobleaching coloring matter, particularly preferred are azo coloring matters, e.g. mono-, bis- or tris-azo coloring matters.

Description

[Detailed description of the invention] <Industrial application field> The present invention relates to optical recording media.

<Prior Art> Various write-once type optical recording disks using dye as a recording layer have been developed.

However, since the dye is photobleached by singlet oxygen,
The present inventors have variously proposed adding a quencher to improve light resistance (Japanese Patent Laid-Open No. 59-557).
No. 94, No. 59-55795, No. 60-159087
No. 60-162691, No. 60-203488, No. 60-163243, etc.).

<Problems to be Solved by the Invention> An object of the present invention is to provide a novel optical recording medium with excellent light resistance.

Such objects are achieved by the present invention described in (1) to (6) below.

(1) An optical recording medium characterized by having a recording layer on a substrate containing a light-absorbing dye having an absorption maximum at 600 to 9000 nm and an azo dye having an absorption maximum at 350 to 600 nm.

(2) The optical recording medium according to (1) above, wherein the recording layer further contains a quencher.

(3) The substrate contains a light-absorbing dye having an absorption maximum at 60C) to 900 nm and a dye having an absorption maximum at 350 to 600 nm, and has an extinction coefficient at recording and reproducing light wavelengths of 700 to 900 nm. k is 0.05 to 0.2
What is claimed is: 1. An optical recording medium characterized in that it has a recording layer, and a reflective layer is laminated on the recording layer.

(4) The optical recording medium according to (3) above, wherein the recording layer further contains a quencher.

(5> The substrate contains a light-absorbing dye having an absorption maximum in the range of 600 to 900 nm and a dye having an absorption maximum in the range of 350 to 600 nm, and the reflectance of reproduction light in the range of 700 to 900 nm is 15% or more. An optical recording medium characterized in that it has a certain recording layer, and this recording layer is enclosed through a gap.

(6) The optical recording medium according to (5) above, wherein the recording layer further contains a quencher.

Effect> In the present invention, an azo dye or the like having a shorter wavelength is added to a light-absorbing dye that absorbs at longer wavelengths in order to improve light resistance.

In general, it is known that when some azo dyes are mixed with, for example, anthraquinone dyes, a phenomenon called catalytic fading or abnormal fading occurs, and the photobleaching of the azo dyes is significantly accelerated. "Chemistry of Functional Dyes" published by CMC, Showa 5S, pages 74 to 76).

In the present invention, this catalytic fading is actively used to oxidize the azo dye preferentially to the light-absorbing dye, thereby extending the life of the light-absorbing dye.

As a result, an unexpected improvement in light resistance was achieved.

Catalytic fading has been observed in various ways in the past, and it has been suppressed using heavy ring oxygen quenchers (see above), but this phenomenon has not been actively utilized. The idea of trying to improve the lifespan of dyes and media is unprecedented.

<Specific configuration> Hereinafter, a specific configuration of the present invention will be explained in detail.

Even if the optical recording medium l of the present invention is a so-called contact type,
A so-called air sandwich type may also be used.

As shown in FIG. 1, the contact type optical recording medium 1 has a recording layer 3 containing a dye on a substrate 2, a reflective layer 4 is formed in close contact with the recording layer 3, and a reflective layer 4 is formed in close contact with the recording layer 3. Preferably, a protective film 5 is formed.

Furthermore, an air sandwich type optical recording medium has a recording layer containing a dye on a substrate, and this is encapsulated through a gap.

The recording layer contains a light-absorbing dye.

The light absorption dye used has an absorption maximum of 600 to 900.
0 m, more preferably 700 to 900 nm, there are no other particular limitations, but cyanine-based, phthalocyanine-based,
One or more of naphthalocyanine-based, anthraquinone-based, azo-based, triphenylmethane-based, biryllium or thiapyrylium salt-based, and metal complex dye-based dyes are preferred.

The cyanine dye is preferably a cyanine dye having an indolenine ring.

Furthermore, a quencher may be mixed with the light-absorbing dye.
Furthermore, an ionic combination of a dye cation and a quencher anion may be used as a light-absorbing dye.

As the quencher, metal complexes such as acetylacetonate, bisdithiol such as bisdithio-α-diketone and bisphenyldithiol, thiocatechol, salicylaldehyde oxime, and thiobisferrate are preferred.

Amine quenchers are also suitable.

The dye constituting the conjugate is preferably a cyanine dye having an indolenine ring, and the quencher is preferably a gold-Km dye such as a bisphenyldithiol metal complex.

For details of preferred dyes and quencher-1 conjugates, see JP-A Nos. 59-24692, 59-55794, 59-55795, 59-81194, and 59-59.
No. 83695, No. 60-18387, No. 60-195
No. 86, No. 60-19587, No. 60-35054, No. 60-36190, No. 60-36191, No. 6
No. 0-44554, No. 60-44555, No. 60-4
No. 4389, No. 60-44390, No. 60-4706
No. 9, No. 60-20991, No. 60-71294,
No. 60-54892, No. 60-71295, No. 60
-71296, 60-73891, 60-73
No. 892, No. 60-73893, No. 60-83892
No. 60-85449, No. 60-92893, No. 60-159087, No. 60-162691, No. 6
No. 0-203488, No. 60-201988, No. 60
-234886, 60-234892, 61-
No. 16894, No. 61-11292, No. 61-112
No. 94, No. 61-16891, No. 61-8384,
No. 61-14988, No. 61-163243, No. 6
1-210539, Japanese Patent Application No. 60-54013, Japanese Patent Application Publication No. 62-30088, 62-32132, 62
No. 31792, the above-mentioned "Chemistry of Functional Dyes", etc.

The quencher may be added separately from the light-absorbing dye or in the form of a conjugate, but the quencher may be added in an amount of 1 mol or less, particularly 0.05 to 0.05 mol, per 1 mol of the total light-absorbing dye. It is preferable to add about 5 mol.

This further improves light resistance.

In the present invention, for these light-absorbing dyes, or light-absorbing dyes and quechers, 350 to 600 nm, particularly 350 to 600 nm,
A dye having an absorption maximum at 550 nm is mixed.

The dye to be used may be one that has the above-mentioned maximum absorption wavelength, but in particular, it has substantially no absorption at the used wavelength of 700 to 900 nm, and the real part of the complex refractive index (refractive index n) at the used wavelength The imaginary part (extinction coefficient k) is preferably 2.8 or less and 0.05 or less, respectively.

By having such optical properties, the color can be selectively photobleached by the catalytic action of the light-absorbing dye.

As such photobleachable dyes, azo dyes such as mono-, bis-, and trisazo are particularly preferred.

As the azo dye, the following are particularly suitable.

A1 Acid Yellow
) 25(C,1,18835λmax 392 nm
) A2 Acid Yellow 29 (C, 1,189001wax 407 nm) A3
Acid Yellow 34 (C, 1, 18890'A, max 408 nm)
A4 Acid Yellow 36 (C, 1,13065λmax 414 nm) A5
Acid Yellow 40 (C, 1,18950 max 412 nm) 86
Acid Yellow 42 (C, 1,22910λmax 410 nm) A7
Palatin First Yellow
e Fast Yellow) B L N(C, 1,
19010λmax 440 nm) A8 Acid Yellow 65 (C, 1, 14170λwax 414 nm) A9
Acid Yellow 99 (C, 1,13900λmax 445 nm) AIO
Flavazin L (Acid Yellow 11) (C, 1, 18820 max 407 nm) All
Acid Alizarin Violet (Acid A1
1zarin Violet) N(C,1,1567
0 circle max 501 nm) A12 Acid Orange 8 (C, 1, 15575
Max 490 nm) A13 Acid Orange 5
1 (C, 1,26550 max 446 nm) A14
Methyl Orange (Acid Orange 52) (C, 1,13025λmax 505 nm) A
15 Acid Orange 62 (C, 1,22870L max 424 r+m)A
16 Acid Orange 74 (C, 1,18745λmax 455 nm) A17
Assisted Red 183 (C, 1,18800 wax 494 nm) A1g
Fast Garnet G
B Cbase (C, 1,11160L max 360 nm) A1
9 Fast Brown B
(Solvent Red 3) (C, 1, 12010 wax 408 nm) A20
First Brown RR (Solvent Brown
1) (C, 1,11785mm max 451 run) A2
1 Direct Red L (
C, 1,23500λmax 500 nm) A22 Bismark Brown R (C, 1,21010λmax 468 nm) A23
Bismarck Brown Y (C, 1,21000λwax 457 r+m) A2
4BrilliantYel
low) (C, 1,24890 elements max 397 nm) A
25 Chrysoidin (Basi
cOrange 2) (C, 1, 11270λmax 449 nm)A
26 Conga Red (Maru max)
497 nm) A27 Sudan r (L max
476 nm) A2g Sudan ■ (λma
x 493 nm) A29 Sudan Orange G (λmax 388 nm) A30 Acid Yellow 23 (C, 1, 19140 e max 425 nm) A31
6-Ptoxy2,6-diami-3,3°-azodipyridine (λmax 433 nm) A32 Fast Corin
th) Vsalt (azoic Diazo No.
,39)(C,1,372201wax 356 nm
)A33 Fast Black
) Ksalt (azoic Diazo No, 3
8) (C, 1,37190L max 457 nm)
A34 Fast Dark Blue
kBlue) R5alt (azoic Diazo
No. 51) (C, 1,37195L wax 4
25 nml In addition, the following azoic dyes or diazo compounds are also suitable.

A35 Fast Blue B
salt (azoic Diazo No, 48) (
C, 1,37235λmax 371 r+m) A36
First Blue B B 5alt (azoic
Diazo No. 20) (C, 1,37175 elements max 395 n[o) A3
7 First Blue RR5alt (azoicDi
azo No. 24) (C, 1,37155 nm max 393 nm) These photobleaching dyes with short wavelength absorption characteristics are light absorption dyes 1
0.01 to 0.4-f-nyl per mole, especially 0.02
It is only necessary to meet the degree of about 0.2-f nyl.

The recording layer is composed of the above-mentioned light-absorbing dye and photobleachable dye, but may also contain a resin or the like.

Although there is no particular restriction on the method of forming the recording layer, in the present invention, it is preferable to form the layer by coating, since it allows greater flexibility and ease in dye selection, medium design, and manufacturing.

Various solvents such as ketone, ester, ether, aromatic, halogenated alkyl, and alcohol solvents can be used for coating the recording layer, and there is a great degree of freedom in selecting the solvent. For application, a spin cord or the like may be used.

As shown in FIG. 1, in the case of a contact type medium, the extinction coefficient (imaginary part of the complex refractive index) k of the recording layer 3 at the recording and reproducing light wavelengths is 0.05 to 0.2. It is preferable that there be.

When k is less than 0.05, the absorption rate of the recording layer decreases, making it difficult to perform recording with normal recording power.

Furthermore, if k exceeds 0.2, the reflectance will fall below 60%, making it difficult to reproduce according to the CD standard.

In this case, extremely favorable results are obtained when k is 0.05 to 0.15.

In addition, the refractive index (real part of the complex refractive index) n is 2.1 to 4.
More preferably, it is 2.2 to 3.3.

When n<2.1, the reflectance decreases and reproduction according to the CD standard tends to become difficult. Moreover, in order to set n>4.0, it becomes difficult to obtain raw material pigments.

In the present invention, the photobleaching dye having absorption at a short wavelength is 60
n and k from 0 to 9000 m, especially from 700 to 900 nm
is small, so light-absorbing pigments such as the above-mentioned light-absorbing pigments,
A quencher mixture or a dye-quencher conjugate having n and k within the above ranges may be selected, or a new molecule may be designed and synthesized.

Note that k for the recording light and reproduction light of the light-absorbing dye is:
Since there are various changes up to about 0 to 2 depending on the skeleton and substituents, there are restrictions on the skeleton and substituents when selecting a dye with k of 0.05 to 0.2, for example. For this reason, there may be restrictions on the coating solvent, or coating may not be possible depending on the substrate material. Alternatively, vapor phase film formation may not be possible. Furthermore, when designing a new molecule, a large amount of effort is required for design and synthesis.

On the other hand, according to the experiments conducted by the present inventors, the k of the dye layer on the stand containing two or more types of dyes corresponds to the k of the dye layer composed of each dye used alone, and has a value approximately corresponding to the mixing ratio thereof. It turned out to be. Therefore, in the present invention, the recording layer may be formed by mixing two or more kinds of dyes.

At this time, in most dye mixing systems, k can be obtained that is approximately proportional to the mixing ratio. That is, when the mixing fraction of the i type of dye and k are respectively C1 and ki, k becomes approximately ΣC1ki. Therefore, by mixing dyes with different k values by controlling the mixing ratio, k=
A dye layer of 0.05 to 0.15 can be obtained. Therefore, the dye to be used can be selected from a very wide range of dye groups.

This can also be applied to improving wavelength dependence. The wavelength of a semiconductor laser is usually in the range of ±10 nm, and in a commercially available CD player, it is necessary to ensure a reflectance of 70% or more in the range of 770 to 790 nm. In general, the value of dyes often has a strong wavelength dependence.
Even if 780nm is a suitable value, 770 or 7
At 90 nm, there is often a large deviation. In such a case, by mixing the second dye, settings can be made such that appropriate n and values are always obtained within the range of 780±10 nm.

As a result, there are no restrictions on film-forming methods such as restrictions on coating solvents, etc., and it is also possible to use dyes that are easy to synthesize and are inexpensive, dyes with good properties, and dyes that are poorly soluble. be able to.

When the recording layer is a mixed layer of light-absorbing dyes, the light-absorbing dyes used may be selected from those in the range of n=1.9 to 6.5 and k=0 to 2.

Note that when measuring n and k, a measurement sample is prepared by forming a recording layer on a predetermined transparent substrate to a thickness of, for example, about 400 to 800 layers under actual conditions. Next, the reflectance through the substrate or from the recording layer side is measured. The reflectance is measured by specular reflection (
5°). Also, measure the transmittance of the sample. From these measurements, e.g.
n and k may be calculated according to "Optics" Ishiguro L. 3, pp. 168-178.

The thickness of such a recording layer is preferably 1000 to 1500. Outside this range, the reflectance decreases, making it difficult to perform reproduction in accordance with the CD standard.

As shown in FIG. 1, a reflective layer 4 is provided in direct contact with such a recording layer 3.

As the reflective layer, a high reflectivity metal such as Au, Ag, Cu, or Pt may be used, and it is particularly preferable to use Au.

The reflective layer has a thickness of 500 Å or more and may be formed by vapor deposition, sputtering, or the like. As a result, the reflectance of the unrecorded portion of the medium through the substrate can be 60% or more, particularly 70% or more.

The base or substrate 2 on which the recording layer is formed is capable of receiving recording light and reproducing light (600 to 900 nm, particularly 700 to 900 nm).
Laser light, especially semiconductor laser light, especially 78 m
0 nm), substantially transparent (preferably transmittance 8
0% or more) resin or glass. This allows recording and reproduction from the back side of the substrate.

The base body is in the shape of a disk of normal size, and when used as a CD, the thickness is about 1.2n+m and the diameter is about 80 to 120 mm.

In this case, it is preferable to use resin as the substrate material, and thermoplastic resins such as polycarbonate resin, acrylic resin, amorphous polyolefin, and TPX are suitable.

It is preferable that tracking grooves be formed on the recording layer forming surface of the substrate.

Further, the tracking portion may be provided with projections and depressions for address signals.

Note that a resin layer (not shown) may be formed on the base by, for example, the 2P method, and the resin layer may be provided with grooves for tracking and irregularities for address signals.

The resin material constituting the resin layer is not particularly limited and may be appropriately selected from known resins used in the so-called 2P method, but radiation-curable compounds are usually used.

Furthermore, it is preferable that a protective film 5 be provided on the reflective layer 4.

The protective film may be formed of various resin materials such as ultraviolet curing resin, and generally has a thickness of about 10 to 1004 cm.

The protective film 5 may be in the form of a layer or a sheet.

To perform recording or additional writing on the contact type optical recording medium 1 having such a configuration, for example, a recording light of 780 nm is applied to the substrate 2.
irradiate in a pulsed manner through the

As a result, the recording layer 3 absorbs light and generates heat, and the substrate 2 is also heated at the same time. As a result, the recording layer material such as the dye melts or decomposes near the interface between the substrate 2 and the recording layer 3, and pressure is applied to the interface between the recording layer 3 and the substrate 2, causing the bottom wall and side wall of the group 23 to be damaged. Transform.

In this case, the melted material and decomposed material of the record H3 has nowhere to go in the closed space, so a part of it swells up to the land portion 21 of the base body, and the rest remains at the bottom of the group 23.

In this way, the decomposed product layer 61 containing decomposed products of the recording material remains in a shape that normally covers the bottoms and boundaries of the groups 23.

The material of the decomposed product layer 61 is usually a material that does not substantially contain the base material, and is composed of a decomposed product of the recording layer material or a mixture of the decomposed product of the recording layer material and the recording layer material.

The thickness of the decomposed product layer 61 is usually about 30 to 90% of the thickness of the recording layer 3.

Generally, a void 63 is formed on the decomposed product layer 61 at the interface with the reflective layer 4, and the decomposed product layer 61 and the void 63 are formed in the bit part 6.

The thickness of the void 63 is usually about 10 to 70% of the thickness of the recording layer 3.

Further, during such a recording process, although the base 2 may not be deformed, the bit portion 6 of the base 2 is usually depressed into a concave shape due to the pressure during heating. The amount of dent in the base increases as the size of the bit part increases, and is usually 0 to 3.
The depth is about 00 people.

Furthermore, the recording layer material or its decomposition products may remain on the gap 63 in close contact with the reflective layer 4 in a very small thickness.

Note that the power of the recording light is approximately 5 to 9 mW, and the linear velocity of rotation of the substrate is approximately 1.2 to 1.4 m/s.

After forming the bit part 6 in this way, for example 78
When a reproduction light of 0 nm is irradiated through the substrate, a phase difference is generated in the light by the bit portion 6, and the reflectance is reduced by 60% or more.

On the other hand, since the unrecorded portion shows a high reflectance of 60% or more, especially 70% or more, reproduction according to the CD standard is possible.

Although the above has been described for the case of single-sided recording media,
A double-sided recording medium can also be obtained by forming a recording layer and a reflective layer on a pair of substrates and integrating them via a protective film or the like.

Next, to explain the air sandwich type optical recording medium, it is possible to form a recording layer on the above-mentioned substrate and integrate it with a protection plate through a gap, or
A recording layer is formed on a pair of substrates, these are integrated through a gap, and the recording layer is encapsulated.

In this case, the thickness of the recording layer is 600 to 900 nm, especially 7 nm.
The reflectance for reproduction light of 00 to 900 r+m is preferably 15% or more, particularly 20 to 40%.

And n in the recording light and reproduction light wavelengths is 2 to 4,
It is preferable that k is 0.2-2.

Moreover, it is preferable that the film thickness is 500 to 1000 people.

Then, by irradiating recording light through the base,
A light-absorbing dye or the like is melted and removed to form a bit.

Known recording and reproduction conditions may be used.

<Example> Example 1 On a polycarbonate resin substrate of 120 mmφ and 1.2 mm thickness having continuous groups, the recording layer N00 shown in Table 1 below was formed.
1.2.3 was installed. On this recording layer, Au was deposited to a thickness of 1000 μm by vapor deposition to form a reflective layer, and an ultraviolet curable resin containing oligoester acrylate was applied and cured by ultraviolet rays to form a protective film with a thickness of 50 μm.
An optical recording disk sample was obtained.

Table 1 Dye Al (λmax 800nm) Recording No., I No., 2nd layer No., 3 Composition (wt%) Light absorption dye A1 Light absorption dye A2 Fast brown RR Quencher-01 n (780nm) k (780nm) 0 0 2 .5 0.10 2.4 0.10 2 O 0 2,4 0,15 Dye A2 (λmax 675nm) Fast
Brown RR (max 451 nm) Quencher Ql (max 870 nm) The recording layer was formed by spin cord coating while rotating the substrate at 500 rpm. For coating/volume, 1.5 wt % solution of dichloroethane was used. The thickness of the dye layer after drying was 1300.

Table 1 shows the 780 nm refractive index (n) and extinction coefficient (k) of the recording layer of each sample.

n and k were determined by forming a film containing the above-mentioned dye on a measurement substrate to a dry film thickness of 600 mm to form a test recording layer, and measuring n and k of this test recording layer.
This measurement was carried out in accordance with the description in "Optics" (written by Kozo Ishiguro, Prefectural Zensho), pages 168 to 178.

A compact disc signal was recorded on each sample obtained using a laser with a wavelength of 780 nm and a power of 7 mW.
Then, it was played back on a commercially available compact disc player.

As a result, the S/N ratio was high and good reproduction could be performed.

Next, several sample pieces were prepared from one optical recording disk after the recording B, and the protective film and reflective layer were peeled off from each sample.

Next, the surface of the substrate was washed with methanol.

In this case, the cleaning conditions include two types of cleaning: weak cleaning by gently shaking in a solvent, and strong cleaning by cleaning while applying ultrasonic waves.
It was classified as a type.

Then, the surface of the substrate after cleaning was examined using a scanning tunneling microscope (S).
TM) The thickness within a group of substrates was determined from the output image.

As a result, in the case of samples subjected to ultrasonic cleaning with strong cleaning power, the bit portions of the substrate were flat or recessed.

In contrast, the bit portion of the substrate of the sample that was cleaned with weak cleaning power was raised.

From these results, the raised parts of the sample cleaned with weak cleaning power are the result of decomposition and alteration of the recording layer material such as dye due to heat, that is, the decomposition product of the recording layer material whose solubility has decreased. It is thought that this is a layer containing

In fact, liquid chromatography is used to collect the residue after washing.
As a result of measurements using absorption spectra, FTIR, MAS, etc., decomposition products exist at the bottom of the bit in the case of weak cleaning power.
It was confirmed that the substrate material was not included.

Next, for each sample, a Xe lamp was irradiated through the substrate, and the reflectance R,,R at 780 nm was measured initially and after 20 hours of irradiation, and was calculated as (1-R) / (1-R,)
was calculated to evaluate the photobleaching property.

The results are shown in Table 2.

Table 2 Recording layer light resistance No. (1-R)/(1-Ro)1 (comparison) 0.14 2 0, 773
When the value is 0.90 or more, the effect of the present invention is obvious.

Example 2 Recording layers Nos. 4 to 6 shown in Table 3 below were formed on a polycarbonate substrate by 800 people.

Table 3 Recording layer No., 4 No., 5 No., 6 Composition (wt%) Light absorption dye A3 Light absorption dye A4 7 Sifted Yellow 36 Quencher-Q2 n (780nm) k (780nm) 2.8 0.07 2. 7 0.06 3 2 0 2.7 0.08 Dye A3 (wax 720r+m) Dye A4 (1
Table 4 shows the deterioration of reflectance after 20 hours of irradiation with a Xe lamp (max. 685 nm) as light resistance.

Table 4 recording layer No.

Light resistance R/R0 4 (comparison) 0.12 5 0.756
0.93 acid yellow 36
(Maru max 414nm) Quencher-Q2 (E max
794 nm) Example 3 In Example 2, the recording layer was the recording layer No. in Table 5 below.
7 to 9, the results shown in Table 6 were obtained.

table 5 Dye A5 (wax 690nm) Record layer No, 7 No, 8 No, 9 Composition (wt%) Light absorption dye A3 Light absorption dye A4 First Garnet GBCbase Quencher-03 n (780nm) k (780nm) 2.5 0.07 2.4 0.06 3 2.3 0.07 first Quencher garnet G.B.C. base (λmax 360nm) Q3 (λrmx970nm) po4- table recording layer No.

Lightfastness R/R0 7 (comparison) 0, 11 0, 79 0, 92 From the above, The effect of the present invention is achieved It's bright Ru.

In addition, good S/N is achieved even with air sandwich structure media.
I was able to get the ratio.

<Effects> According to the present invention, the light resistance of the recording layer is extremely high, the reproduction deterioration of the medium is significantly reduced, and the light stability is extremely high.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a partial sectional view showing a contact type optical recording medium according to the present invention. Explanation of symbols 1... Optical recording medium 2... Substrate 21... Land portion 23... Group 3... Recording layer 4... Reflective layer 5... Protective film 6... Bit portion 61...Decomposed product layer 63...Void

Claims (6)

[Claims] (1) An optical recording medium characterized by having a recording layer on a substrate containing a light-absorbing dye having an absorption maximum in the range of 600 to 900 nm and an azo dye having an absorption maximum in the range of 350 to 600 nm. (2) The optical recording medium according to claim 1, wherein the recording layer further contains a quencher. (3) The substrate contains a light-absorbing dye having an absorption maximum in the range of 600 to 900 nm and a dye having an absorption maximum in the range of 350 to 600 nm, and has an extinction coefficient k at recording and reproducing light wavelengths of 700 to 900 nm. 1. An optical recording medium comprising a recording layer having a thickness of 0.05 to 0.2, and a reflective layer laminated on the recording layer. (4) The optical recording medium according to claim 3, wherein the recording layer further contains a quencher. (5) A record containing a light-absorbing dye having an absorption maximum in the range of 600 to 900 nm and a dye having an absorption maximum in the range of 350 to 600 nm on the substrate, and having a reflectance of reproduction light of 700 to 900 nm of 15% or more. 1. An optical recording medium characterized in that the recording layer is enclosed with a gap therebetween. (6) The optical recording medium according to claim 5, wherein the recording layer further contains a quencher.