JPH0660427A - Optical disk recording disk - Google Patents

Abstract

PURPOSE:To maintain satisfactory strength by forming a dye-based recording layer on a substrate by coating and further forming a reflecting layer on the recording layer and a protective layer on the reflecting layer. CONSTITUTION:A reflecting layer 4 of Ag or Ag alloy is formed on a dye-based recording layer 3 and a protective layer 5 contg. N and one or more among Ti, Zr, Cr, Mg, Ca and Ba is formed on the reflecting layer 4. Since the protective layer is formed on the reflecting layer, satisfactory reflectivity adaptable to stand-dards on CD is ensured and the deterioration of the reflecting layer and the dye can be prevented. Since the protective layer is formed, satisfactory strength can be maintained even if the reflecting layer is made thin.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical recording disk having a coating type recording layer containing a dye as a main component.

[0002]

2. Description of the Related Art In recent years, various optical recording disks such as a write-once type and a rewritable type have been attracting attention as a large capacity information carrying medium. Among the write-once type optical recording disks, those using a recording layer containing a dye as a main component can be manufactured at low cost because the recording layer can be formed by coating.

As an optical recording disc using a recording layer containing a dye as a main component, a so-called air sandwich structure in which an air layer is provided on the recording layer has been conventionally used, but recently, it is reflected on the surface of the recording layer. An optical recording disk capable of reproducing in compliance with the compact disk (CD) standard has been proposed by providing layers in close contact (Nikkei Electronics January 23, 1989, No. 465, P.
107, Kinki Chemical Society Functional Dye Subcommittee, 198
March 3, 9th, Osaka Science and Technology Center, PROCEEDINGS SP
IE-THE INTERNATIONAL SOCIETY FOR OPTICAL ENGINEERI
NG VOL.1078 PP80-87, "OPTICAL DATA STORAGE TOPICAL
MEETING "17-19, JANUARY 1989 LOS ANGELES, etc.) This optical recording disc is formed by stacking a dye layer, a reflective layer, and a protective film in this order on a transparent substrate. By providing the above, it is possible to configure a CD standard disc having a total thickness of 1.2 mm.

An optical recording disk using a dye in the recording layer is a C
In order to reproduce with a D player, the reflectivity of the Al reflective layer used in a normal CD is insufficient, so the Au reflective layer is used in the above proposal. Au has high reflectance and good corrosion resistance, but is expensive. For this reason, it is considered to use a high-reflectance metal other than Au, which is inexpensive, for example, Ag or an Ag-based alloy such as Ag-Cu.

When the protective film on the reflective layer is made of a resin material like CD, oxygen and water vapor in the air easily enter through the protective film, but materials other than Au have low corrosion resistance, and therefore the reflective layer is When the potential balance is lost on the protective film side of the reflective layer, it may spread to the dye layer side and deteriorate the dye. Therefore, sufficient reliability cannot be obtained.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to realize an optical recording disk having a recording layer containing a dye as a main component, which is inexpensive and highly reliable.

[0007]

The above objects are achieved by the present invention described in (1) to (3) below.

(1) A coating type recording layer containing a dye as a main component is provided on a substrate, a reflective layer is provided on the recording layer, and a protective layer is provided on the reflective layer. Is Ag or Ag
And a protective layer made of Ti, Zr, Cr,
An optical recording disk comprising N and at least one element selected from the group consisting of Mg, Ca and Ba.

(2) The optical recording disk according to (1), wherein the protective layer has a thickness of 100 A or more.

(3) The optical recording disk according to (1) or (2), wherein the thickness of the reflective layer is 200 A or more.

[0011]

The optical recording disk of the present invention is a contact-type optical recording disk which has a recording layer containing a dye, a reflective layer and a protective layer made of a nitride in this order on a substrate and which is compatible with the CD standard. is there.

In order to satisfy the required reflectance and to secure the storage durability of the recording layer and the reflective layer itself, the reflective layer of the contact type optical recording disk corresponding to the CD standard which uses a dye in the recording layer is usually Since the thickness is 600 A or more, it is difficult to reduce the cost when the reflective layer is made of Au. However, when an inexpensive reflective layer such as Ag or an Ag-based alloy is used, the reflective layer and the dye are easily deteriorated.

In the present invention, by providing a protective layer made of a nitride on the Ag-based reflection layer, a sufficient reflectance that can comply with the CD standard can be ensured, and the deterioration of the reflection layer and the dye can be prevented. Further, by providing the protective layer, sufficient strength can be maintained even if the reflective layer is thin.

Further, by adjusting the nitrogen content of the protective layer to an appropriate value, it is possible to obtain a color similar to Au, so that it can be used as a substitute for Au in terms of appearance.

[0015]

Specific Structure The specific structure of the present invention will be described in detail below.

The optical recording disk of the present invention is an optical recording disk which has a reflective layer in close contact with a recording layer containing a dye as a main component and which can be reproduced in accordance with the CD standard. One embodiment of the optical recording disk of the present invention is shown in FIG.

The optical recording disk 1 shown in FIG. 1 has a recording layer 3 containing a dye as a main component on the surface of a substrate 2, and adheres closely to the recording layer 3 to form a reflective layer 4, a protective layer 5 and an organic protective layer. It is a contact-type optical recording disk having a coat 6.

The substrate 2 has recording light and reproducing light (wavelength 60).
It is formed of a resin or glass that is substantially transparent (preferably a transmittance of 88% or more) to a semiconductor laser beam having a wavelength of about 0 to 900 nm, particularly 770 to 800 nm, particularly 780 nm. This enables recording and reproduction from the back side of the substrate.

The substrate 2 is a disc of a normal size, and has a thickness of 1.2 when used as a recordable CD.
The diameter is about 80 mm and the diameter is about 80 to 120 mm.

As the substrate material, it is preferable to use a resin, and various thermoplastic resins such as polycarbonate resin, acrylic resin, amorphous polyolefin, TPX and the like are preferable. The substrate 2 may be manufactured by a known method such as injection molding. At that time, it is preferable to form a predetermined pattern such as the groove 21 on the surface of the substrate for tracking or addressing. After the substrate 2 is manufactured, a resin layer having a predetermined pattern such as a groove may be formed by the 2P method or the like.

The groove is preferably a spiral continuous groove having a depth of 500 to 3000 A, a width of 0.2 to 1.1 μm, especially 0.3 to 0.6 μm, and a land (adjacent grooves are adjacent to each other). Portion) width is 0.5-1.
It is preferably 4 μm, particularly 1.0 to 1.3 μm. With such a configuration of the groove, a good tracking signal can be obtained without lowering the reflection level of the groove portion. It should be noted that the groove may be provided with unevenness for address signals. Moreover, it is preferable that the recording light is irradiated onto the recording layer in the groove.

The recording layer 3 may contain only one type of dye, or may have a structure in which two or more types of dyes are compatible with each other.

When recording a CD signal, the extinction coefficient (imaginary part of the complex refractive index) k of the recording layer 3 at the wavelengths of the recording light and the reproducing light is preferably 0.03 to 0.25. When k is less than 0.03, the absorptivity of the recording layer is reduced, and it becomes difficult to perform recording with normal recording power.
Further, when k exceeds 0.25, the reflectance falls below 60%, making it difficult to perform reproduction according to the CD standard. Note that k is 0.03 to 0.20, especially 0.03 to
A value of 0.15 gives very favorable results.

The refractive index (real part of complex refractive index) n of the recording layer 3 is 1.8 to 4.0, more preferably 2.0 to 4.0.
It is preferably 3.0. When n <1.8, the reflectance is lowered and the signal modulation degree is reduced, which tends to make it difficult to reproduce by a CD player. Further, in order to make n> 4.0, it is difficult to obtain the raw material dye.

The light absorbing dye used in the recording layer 3 has an absorption maximum of 600 to 900 nm, preferably 600 to 900 nm.
800 nm, more preferably 650 to 750 nm,
Other than that, there is no particular limitation, and for example, one or more of cyanine-based, phthalocyanine-based, naphthalocyanine-based, anthraquinone-based, azo-based, triphenylmethane-based, pyrylium or thiapyrylium salt-based, squarylium-based, croconium-based, metal complex dye-based, etc. Two or more kinds may be appropriately selected according to the purpose.

As the cyanine dye, a cyanine dye having an indolenine ring which may have an aromatic condensed ring, particularly a benzoindolenine ring is preferable.

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

As the quencher, acetylacetonate-based, bisdithiol-based such as bisdithio-α-diketone and bisphenyldithiol-based, thiocatechol-based, salicylaldehyde oxime-based, and thiobisphenolate-based metal complexes are preferable. . Further, amine compounds having a nitrogen radical cation and amine quenchers such as hindered amines are also suitable.

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

Details of preferable dyes, quenchers and conjugates are disclosed in JP-A-59-24692 and 59-55.
No. 794, No. 59-55795, No. 59-81194.
No. 59-83695, No. 60-18387, No. 60-19586, No. 60-19587, No. 60-
35054, 60-36190, 60-361
No. 91, No. 60-44554, No. 60-44555.
No. 60, No. 60-44389, No. 60-44390, No. 60-47069, No. 60-20991, No. 60-.
No. 71294, No. 60-54892, No. 60-712.
No. 95, No. 60-71296, No. 60-73891.
No. 60, No. 60-73892, No. 60-73893, No. 60-83892, No. 60-85449, No. 60-
92893, 60-159087, 60-16
No. 2691, No. 60-203488, No. 60-201.
No. 988, No. 60-234886, No. 60-2348.
No. 92, No. 61-16894, No. 61-11292
No. 61-11294, No. 61-16891, No. 61-8384, No. 61-14988, No. 61-1.
63243, 61-210539, Japanese Patent Application No. 60-
No. 54013, JP-A Nos. 62-30088 and 62-3.
No. 2132, No. 62-31792, CMC Publishing "Chemistry of Functional Dyes" P74-76 and the like.

The quencher may be added separately from the light absorbing dye or may be added in the form of a conjugate, but it is not more than 1 mol, particularly 0.05 mol per 1 mol of the total light absorbing dye. ~
It is preferable to add about 0.5 mol. This allows
Light resistance is improved.

The dye used in the recording layer may be selected from the above light-absorbing dye, dye-quencher mixture, and dye-quencher conjugate having n and k in the above range. It may be synthesized by newly designing a molecule.

The k of the dye with respect to the recording light and the reproducing light varies variously from 0 to 2 depending on its skeleton and substituents. Therefore, for example, when selecting a dye having k of 0.03 to 0.25. Is limited in its skeleton and substituents.
For this reason, there are cases in which the coating solvent is limited, or coating cannot be performed depending on the substrate material. Alternatively, vapor phase film formation may not be possible. In addition, a large amount of labor is required for designing and synthesizing a new molecule.

On the other hand, according to the experiments by the present inventors, the k of the mixed dye layer containing two or more kinds of dyes is almost equal to the mixing ratio depending on the k of the dye layer composed of each dye to be used. It turned out to be the corresponding value. Therefore, in the present invention, the recording layer 3 may be formed by compatibilizing two or more kinds of dyes.

At this time, k which is almost proportional to the mixing ratio can be obtained in most of the dye mixing systems. That is, i
The mixing fractions and k of the dyes of the species are Ci and ki, respectively.
Then, k becomes almost ΣCiki. Therefore, k
It is possible to obtain a dye layer having k = 0.03 to 0.25 by mixing the dyes having different values with each other while controlling the mixing ratio. Therefore, the dye to be used can be selected from a very wide range of dye groups.

This can also be applied to improve the wavelength dependence. The wavelength of the semiconductor laser is usually in the range of ± 10 nm, and in a commercially available CD player, it is 770 nm to 79 nm.
It is necessary to secure a reflectance of 70% or more in the range of 0 nm. Generally, the k value of a dye has a large wavelength dependency, and even if it is an appropriate value at 780 nm, it often deviates greatly at 770 nm or 790 nm. In such a case, by mixing the second dye, it can be set so that appropriate n and k values are always obtained in the range of 780 ± 10 nm.

As a result, restrictions such as restrictions on the coating solvent are alleviated, and it is possible to use dyes that are easy to synthesize and inexpensive, use dyes that have good characteristics, and use dyes that are sparingly soluble. can do.

When the recording layer 3 is a mixed dye layer, the dye to be used may be selected from those in the range of n = 1.6 to 6.5 and k = 0 to 2.

When measuring n and k, a recording layer is formed on a predetermined transparent substrate to a thickness of, for example, about 400 to 1000 A under actual conditions to prepare a measurement sample. Next, the reflectance of the measurement sample through the substrate or the reflectance from the recording layer side is measured. The reflectance is measured by specular reflection (about 5 °) using the recording / reproducing light wavelength. In addition, the transmittance of the sample is measured. From these measured values, for example, Kyoritsu Zensho "Optics" Kozo Ishiguro P
According to 168 to 178, n and k may be calculated.

The recording layer is formed by a spin coating method in which a coating solution containing a dye and an organic solvent is used and the coating solution is spread and coated on a rotating substrate.

The organic solvent used for the coating liquid for recording formation may be appropriately selected from alcohols, ketones, esters, ethers, aromatics, alkyl halides and the like according to the dye used. However, an organic solvent having two or more functional groups in one molecule is suitable.

After spin coating, the coating film is dried if necessary.

The thickness of the recording layer thus formed is appropriately set depending on the desired reflectance and the like, but is usually about 1000 to 3000 A.

A reflective layer 4 is provided on the recording layer 3 so as to be in direct contact therewith. The reflective layer 4 is made of Ag or an Ag-based alloy, and Ag is preferable because of its high reflectance and good corrosion resistance. As an Ag-based alloy, in addition to Ag, Cu, Ti, V, Ta, Cr, Mo, W, Mn, F
It is preferable to contain one or more elements selected from e, Co, Rh, Ni, Pd, Pt, Au, Al, etc., but in order to obtain a high reflectance, the Ag content should be 40 atomic% or more. Preferably. The Ag-Cu alloy has been used preferably in the past because it has a color similar to Au. However, in the present invention, since the protective layer has a color similar to Au, it is not necessary to use the Ag-Cu alloy in the reflective layer.

A protective layer 5 is provided on the reflective layer in close contact with it. The protective layer 5 contains N and at least one element selected from the group consisting of Ti, Zr, Cr, Mg, Ca and Ba. Of these, Ti is particularly preferable. The nitrogen content in the protective layer is not particularly limited, and may be appropriately selected from a range having good corrosion resistance and a range exhibiting a desired gold color. Usually, the atomic ratio N / N of the nitrogen N and the metal element M /
It is preferable that M is about 0.2 to 5.

To form the reflective layer 4 and the protective layer 5,
Various vapor deposition methods such as sputtering may be used. N
When it contains, the reactive sputtering may be used, and the sputtering target may be nitride.

The thickness of the reflective layer 4 is preferably 200 A or more. If the thickness of the reflective layer is less than the above range, the reflectance tends to be insufficient. The thickness of the protective layer 5 is 10
It is preferably 0 A or more. If the thickness of the protective layer is less than the above range, the protective effect of the reflective layer tends to be insufficient. The total thickness of the reflective layer and the protective layer is 60.
It is preferably 0 A or more. If the total thickness is less than the above, the strength of the laminate of the reflective layer and the protective layer tends to be insufficient. There is no upper limit to the total thickness, but 20
It does not have to be thicker than 00A.

By forming the reflective layer as described above, the reflectance of 90% or more can be obtained with the reflective layer alone, and the reflectance (unrecorded portion) through the substrate when used as an optical recording disk is , 60% or more, particularly 70% or more.

It is preferable to provide the organic protective coat 6 on the protective layer 5 as shown in the figure, but it is not necessary to provide it.

The organic protective coat 6 is preferably formed by a spin coating method in order to avoid damage to the protective layer 5, but a screen printing method, a dipping method, a spray coating method or the like may be used. The conditions for forming the organic protective coat 6 are not particularly limited and may be appropriately determined according to the viscosity of the coating liquid, the target thickness, and the like.

The thickness of the organic protective coat is preferably about 1 to 20 μm. When the thickness is less than the above range,
The effect of the provision tends to be insufficient. When the thickness exceeds the above range, cracks are likely to occur due to shrinkage during curing, and the disc is likely to be warped.

If necessary, the organic protective coat may have a multi-layered structure of two or more layers.

The organic protective coat 6 is preferably composed of a radiation curable resin. Specifically, it is preferably composed of a radiation-curable compound or a substance obtained by radiation-curing a composition for polymerization thereof. Examples of such compounds include acrylic double bonds having unsaturated double bonds that are sensitive to ionization energy and exhibit radical polymerizability, such as acrylic double bonds such as acrylic acid, methacrylic acid, or their ester compounds, and diallyl phthalate. Examples thereof include monomers, oligomers and polymers having or introduced in the molecule a group capable of being crosslinked or polymerized by radiation such as an allyl double bond, an unsaturated double bond such as maleic acid and a maleic acid derivative. These are preferably polyfunctional, particularly trifunctional or more, and may be used alone or in combination of two or more.

The radiation curable monomer has a molecular weight of 2
A compound of less than 000 has a molecular weight of 20 as an oligomer.
Those of 00 to 10,000 are preferable. These include styrene, ethyl acrylate, ethylene glycol diacrylate, ethylene glycol dimethacrylate, diethylene glycol diacrylate, diethylene glycol methacrylate, 1,6-hexane glycol diacrylate, 1,6-hexane glycol dimethacrylate, etc., but especially preferred As, pentaerythritol tetraacrylate (methacrylate), pentaerythritol acrylate (methacrylate), trimethylolpropane triacrylate (methacrylate), trimethylolpropane diacrylate (methacrylate), acrylic modified urethane elastomer,
Alternatively, those into which a functional group such as COOH is introduced, acrylate (methacrylate) of phenol ethylene oxide adduct, acrylic group (methacrylic group) or ε-in the pentaerythritol condensed ring shown in Japanese Patent Application No. 62-072888. Examples thereof include compounds having a caprolactone-acrylic group, and acrylic group-containing monomers and / or oligomers such as special acrylates disclosed in Japanese Patent Application No. 62-072888. Besides this,
Examples of radiation-curable oligomers include oligoester acrylates, acrylic modified urethane elastomers, and those into which a functional group such as COOH is introduced.

In addition to the above compounds, or in place of this, a radiation curable compound obtained by radiation-sensitively modifying a thermoplastic resin may be used. Specific examples of such radiation curable resins include acrylic double bonds having an unsaturated double bond exhibiting radical polymerizability, acrylic double bonds such as methacrylic acid, or ester compounds thereof, and diallyl phthalate. It is a resin in which a group such as an allyl double bond, an unsaturated bond such as maleic acid or a maleic acid derivative, which is crosslinked or polymerized by irradiation with radiation is contained or introduced in the molecule of the thermoplastic resin. Examples of thermoplastic resins that can be modified into radiation-curable resins include vinyl chloride copolymers, saturated polyester resins, polyvinyl alcohol resins, epoxy resins, phenoxy resins, fibrin derivatives and the like. Other resins that can be used for radiation-sensitive modification include polyfunctional polyester resins, polyetherester resins, polyvinylpyrrolidone resins and derivatives (P
(VP olefin copolymer), polyamide resin, polyimide resin, phenol resin, spiro acetal resin, acrylic resin containing at least one of acrylic ester and methacrylic ester having a hydroxyl group as a polymerization component are also effective.

Since the coating composition for polymerization is cured by irradiation of radiation, especially irradiation of ultraviolet rays, it is preferable that the composition for polymerization contains a photopolymerization initiator or a sensitizer. The photopolymerization initiator or sensitizer to be used is not particularly limited and may be appropriately selected from usual ones such as acetophenone type, benzoin type, benzophenone type and thioxanthone type. A plurality of compounds may be used in combination as the photopolymerization initiator or the sensitizer. The content of the photopolymerization initiator in the composition for polymerization may be usually about 0.5 to 5% by weight. Such a composition for polymerization may be synthesized according to a conventional method, or may be prepared using a commercially available compound.

As a composition containing a radiation-curable compound for forming an organic protective coat, a composition containing an epoxy resin and a photocationic polymerization catalyst is also preferably used.

The epoxy resin is preferably an alicyclic epoxy resin, and particularly preferably one having two or more epoxy groups in the molecule. As alicyclic epoxy resin,
3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate, bis- (3,4
-Epoxycyclohexylmethyl) adipate, bis-
(3,4-epoxycyclohexyl) adipate, 2-
(3,4-epoxycyclohexyl-5,5-spiro-
One or more of 3,4-epoxy) cyclohexane-meta-dioxane, bis (2,3-epoxycyclopentyl) ether, vinylcyclohexene dioxide and the like are preferable. The epoxy equivalent of the alicyclic epoxy resin is not particularly limited, but 60 to 3 because good curability can be obtained.
00, particularly preferably 100 to 200.

The photocationic polymerization catalyst may be any known one and is not particularly limited. For example, a complex of one or more metal fluoroborate and boron trifluoride,
Bis (perfluoroalkylsulfonyl) methane metal salt, aryldiazonium compound, aromatic onium salt of 6A group element, aromatic onium salt of 5A group element, 3A group
Dicarbonyl chelate of Group 5A element, thiopyrylium salt, MF ₆ anion (where M is P, As or S
Group 6A elements having b), triarylsulfonium complex salts, aromatic iodonium complex salts, aromatic sulfonium complex salts and the like can be used, and in particular, polyarylsulfonium complex salts, aromatic sulfonium salts or iodonium salts of halogen-containing complex ions, 3A It is preferable to use one or more aromatic onium salts of Group 5A group elements and Group 6A elements.

A photocationic polymerization catalyst containing an organometallic compound and a photodegradable organosilicon compound can also be used. Since such a cationic photopolymerization catalyst is a non-strong acid type, it is possible to avoid adverse effects on the highly corrosive recording layer of the magneto-optical recording disk. As the organometallic compound, Ti, V, Cr, Mn, Fe, Co,
A complex compound in which an alkoxy group, a phenoxy group, a β-diketonato group or the like is bonded to a metal atom such as Ni, Cu, Zn, Al or Zr is preferable. Of these, organoaluminum compounds are particularly preferable, and specifically, trismethoxyaluminum, trispropionatoaluminum, tristrifluoroacetylaluminum, and trisethylacetoacetonatoaluminum are preferable.

The organic silicon compound having photodegradability produces silanol by irradiation with light such as ultraviolet rays,
A silicon compound having a peroxysilano group, an o-nitrobenzyl group, an α-ketosilyl group or the like is preferable.

The content of the photocationic polymerization catalyst in the composition is 0.05 to 0.
It is preferably 7 parts by weight, particularly 0.1 to 0.5 parts by weight.

Among these, it is preferable that a radiation-curable compound having an acrylic group is used, and a coating film containing a photopolymerization sensitizer or an initiator is radiation-cured, especially ultraviolet-cured.

When forming the organic protective coat, the coating film of the composition for polymerization as described above is irradiated with ultraviolet rays to be cured, but in some cases, it may be irradiated with ultraviolet rays after being heated. Instead, it may be irradiated with an electron beam or the like. The intensity of ultraviolet rays applied to the coating film is usually about 50 mW / cm ² or more,
The irradiation dose may be usually about 500 to 2000 mJ / cm ² . Further, as the ultraviolet ray source, a normal one such as a mercury lamp may be used. The above compounds undergo radical polymerization upon irradiation with ultraviolet rays.

If desired, the organic protective coat may contain various pigment particles.

A label printing layer composed of at least one printing layer may be provided on the organic protective coat 6. The label printing layer is preferably formed by printing a radiation curable resin composition containing various pigments and curing the composition, but other than this, a thermosetting ink may be used.

In order to perform recording or additional recording on the optical recording disc 1 having such a structure, for example, recording light of 780 nm is used.
Irradiation is performed in a pulse shape through the substrate 2 to change the light reflectance of the irradiation portion. When the recording light is irradiated, the recording layer 3 absorbs the light and generates heat, and at the same time, the substrate 2 is also heated. As a result, in the vicinity of the interface between the substrate 2 and the recording layer 3, the recording layer material such as a dye is melted or decomposed, pressure is applied to the interface between the recording layer 3 and the substrate 2, and the bottom surface or side wall of the groove is deformed. Sometimes.

[0068]

EXAMPLES The present invention will be described in more detail below by showing specific examples of the present invention.

An optical recording disk sample having the structure shown in FIG. 1 was prepared. First, a recording layer 3 containing a dye was formed by a spin coating method on a polycarbonate resin substrate 2 having a spiral continuous groove and a diameter of 120 mm and a thickness of 1.2 mm. A reflective layer 4 and a protective layer 5 were formed on the recording layer 3, and an organic protective coat 6 was formed in that order.

The coating liquid used for forming the recording layer 3 contains a dye and an organic solvent. As the dye, the following dyes A1 and A2 and a singlet oxygen quencher were used, and the content of A1 in the dye was The content of A2 was 60% by weight, the content of A2 was 30% by weight, and the content of singlet oxygen quencher was 10% by weight.

[0071]

[Chemical 1]

As the organic solvent, diacetone alcohol was used. The pigment content in the coating liquid was 5% by weight. The thickness of the recording layer was 200 nm.

The reflective layer and the protective layer were formed by the sputtering method. The elements contained and the thickness of each layer are shown in Table 1 below. An Ag ₈₀ Cu ₂₀ target was used for forming the reflective layer, and a TiN target was used for forming the protective layer. For comparison, a sample having no protective layer was also prepared.

The organic protective coat was formed by applying an ultraviolet curable resin (SD-17, manufactured by Dainippon Ink & Co., Ltd.) by spin coating and curing it with ultraviolet light. The thickness of the organic protective coat after curing was 5 μm.

Each of the above samples was reproduced by a commercially available compact disc player, and the BLER (block error rate) was measured. Also, 80 ° C, 80% R
The same measurement was carried out after 100 hours of storage in the H environment. The results are shown in Table 1. BLER was measured for 10 minutes, and the average value per second was shown. The BLER CD standard is 220 (counts / second) or less.

[0076]

[Table 1]

From the results shown in Table 1, the effect of the present invention is clear.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional view showing an example of an optical recording disk of the present invention.

[Explanation of symbols]

 1 Optical recording disk 2 Substrate 21 Groove 3 Recording layer 4 Reflective layer 5 Protective layer 6 Organic protective coat

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Atsuko Jin 1-13-1, Nihonbashi, Chuo-ku, Tokyo TDC Inc.

Claims (3)

[Claims] 1. A coating type recording layer containing a dye as a main component is provided on a substrate, a reflective layer is provided on the recording layer, and a protective layer is provided on the reflective layer. An optical recording disc comprising Ag or an Ag-based alloy, wherein the protective layer contains N and one or more elements selected from the group consisting of Ti, Zr, Cr, Mg, Ca and Ba. 2. The optical recording disk according to claim 1, wherein the protective layer has a thickness of 100 A or more. 3. The optical recording disk according to claim 1, wherein the reflective layer has a thickness of 200 A or more.