JPH0954980A - Optical recording medium - Google Patents

Abstract

(57) Abstract: A recording layer containing an organic dye, which is provided on a transparent substrate directly or via another layer, and provided on the recording layer directly or via another layer An optical recording medium comprising at least a light-reflecting layer, wherein the transparent substrate contains an organic dye, and the amount of light transmission in a wavelength region below the wavelength of the laser light used is 25% or less. [Effect] By containing a specific organic dye in an appropriate ratio in a transparent substrate, an optical recording medium having excellent reliability that prevents deterioration of light resistance of a recording layer containing the organic dye and can withstand long-term storage Made possible.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical recording medium, and more particularly to a recordable optical recording medium.

[0002]

2. Description of the Related Art Conventionally, as an optical recording medium, pre-pits and pre-grooves for reproducing recorded information are previously formed on a substrate such as a translucent polycarbonate using a means such as a press, and the pits are further formed. A on the formed surface
A read-only optical recording medium in which a light reflecting layer made of a metal film of u, Al, or the like is further formed, and a protective layer made of a photocurable resin is further formed on the light reflecting layer is a compact disc (hereinafter referred to as a CD.
Abbreviated) has been put to practical use. This CD is music,
It is widely used for the purpose of storing and reproducing images, data, programs, etc. The specifications relating to the recording and reproducing signals of this CD are defined as the CD standard, and reproducing devices that comply with this standard are widely used as CD players.

A CD-Recordable (hereinafter abbreviated as CD-R) as a write-once type optical recording medium compatible with the CD standard.
Have been proposed and developed [for example, Nikkei Electronics No. 465, P.I. 107, January 23, 1989, OPTICAL DATA STORAGE DIGEST SERIES vol.1 P45,
1989, JP-A-2-132656, JP-A-2-1684
46, JP-A-3-215466, etc.]. This CD
-R has a recording layer, a reflective layer, and a protective layer laminated in this order on a transparent resin substrate, and by irradiating the recording layer with a high-power laser beam, the recording layer undergoes a physical or chemical change. Raise and record the information in the form of pits. The pit information can be reproduced by irradiating the formed pit portion with a low-power laser beam and detecting a change in reflectance. These CD-R media are 770-
It is compatible with CD players and CD-ROM players because it records and reproduces using a near infrared semiconductor laser of 830 nm and complies with CD standards such as Red Book, Yellow Book, and Orange Book. Have.

Recently, development of semiconductor lasers having a wavelength shorter than 770 nm has progressed, and red semiconductor lasers having wavelengths of 680 nm and 630 nm have been put into practical use [eg Nikkei Electronics, No. 592, p. 65, 1993
October 11, issue]. Since the beam spot can be reduced by shortening the wavelength of the recording / reproducing laser, an optical recording medium capable of high-density recording / reproducing becomes possible. In fact, a large-capacity optical recording medium and a player capable of recording a moving image for a long time are being studied by shortening the wavelength of a semiconductor laser and data compression technology [eg, Nikkei Electronics, N.
o. 589, P.P. 55, August 30, 1993 issue, N
o. 594, P.I. 169, November 8, 1993].
While a high-density optical recording medium and a player using such a red laser are being studied, it is necessary for a CD-R medium to meet this requirement. However, there is a problem that the laser energy increases with the shortening of the wavelength of the laser beam, and the laser beam deteriorates due to the reproducing beam and cannot be put to practical use.

In the CD-R medium, organic dyes such as cyanine dyes, phthalocyanine dyes and azo dyes are used for the recording layer. Among these organic dyes, the phthalocyanine dye is excellent in light resistance, but there is still room for improvement in light resistance. In particular, it became necessary to prevent deterioration of color resistance in reproduction light stability due to the shortening of the wavelength of laser light.

[0006] In order to improve the light fastness, attempts have been made to improve the organic dye itself and the additives, but there is a limit to this, and the range of selection of the organic dye as a recording material is narrowed. .

In JP-A-3-41640, JP-A-4-61640, JP-A-4-162225, JP-A-4-167239, and JP-B-5-70213, a light absorber is contained in the substrate or the substrate. It has been proposed that a light absorber be laminated on the surface to cut off light other than the recording / reproducing wavelength. However, the specific examples used for the CD-R medium are scarce and it is not clear what kind of dye is effective. The present inventors have focused on a method of incorporating an organic dye as a light absorber in a substrate having a longer optical path length than in the case where the light absorber is laminated on the substrate surface. In this case, the organic dye contained in this substrate has high light resistance and heat resistance,
It must be compatible with the substrate material, but there is no publication that describes the properties of these materials.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems, that is, in an optical recording medium having an organic recording layer, it is possible to prevent deterioration of the recording layer against light and to endure long-term storage. It is to propose an optical recording medium that can maintain excellent reliability.

[0009]

DISCLOSURE OF THE INVENTION The inventors of the present invention have conducted extensive studies to solve the above problems, and as a result, by incorporating a specific organic dye in a transparent substrate, recording and reproduction having excellent light resistance. The inventors have found a possible optical recording medium and completed the present invention.

That is, the present invention provides a recording layer containing an organic dye, which is provided on a transparent substrate directly or via another layer, and a light provided on the recording layer directly or via another layer. An optical recording medium comprising at least a reflective layer, wherein the transparent substrate contains an organic dye, and the amount of light transmission in a wavelength region below the wavelength of the laser light used is 25% or less, An optical recording medium according to claim 1, wherein the organic dye contained in the substrate is an anthraquinone dye represented by the formula (1) [Chemical Formula 3] having an absorption of 750 nm or less.

[0011]

Embedded image (In the formula, R ₁ , R ₂ , R ₃ , R ₄ , R ₅ , R ₆ , R ₇ and R ₈ are each independently a hydrogen atom, a halogen atom, a hydroxyl group, a carboxyl group, a sulfone group, a nitro group or a cyano group. Group, substituted or unsubstituted alkyl group, alkoxy group,
Allyl group, aryl group, aryloxy group, alkylthio group, arylthio group, aralkyl group, acyl group, alkylcarboxyl group, aralkyl group, ester group, carbamoyl group, vinyl group, acylamino group, sulfamoyl group, phenylazo group, pyridinoazo group, Represents an alkylcarbonylamino group, an alkylsulfonamino group, an alkylamino group, an arylamino group, a sulfonamide group, an amino group, an alkylcarbonyl group, an alkylsulfone group, or a phenyl group, and R ₂ and R ₃ are cyclic groups via a linking group. May be formed. An optical recording medium in which the transparent substrate contains polycarbonate as a main component, or the recording layer contains a phthalocyanine-based dye represented by the formula (2) [Chemical Formula 4] as a main component. Is.

[0012]

Embedded image(In the formula, Y₁, Y₂, Y_Three, Y_Four, Y_Five, Y₆, Y₇Over
And Y₈Are each independently an unsubstituted or substituted group having 1 to 20 carbon atoms.
Substituted hydrocarbon group, unsubstituted or substituted carbonization having 1 to 20 carbon atoms
Hydrogen oxy group, unsubstituted or substituted carbonization having 1 to 20 carbon atoms
Represents a hydrogen thio group, Y₁And Y₂, Y_ThreeAnd Y_Four, Y_FiveAnd Y
₆, And Y₇And Y₈Next to each other in each combination of
When they are in contact with each other, the groups that may be connected to form a ring are shown.
You. On the other hand, A ₁, A₂, A_ThreeAnd A_FourEach independently
Represents a rogen atom and a nitro group. l₁, L₂, L_ThreeAnd l
_FourRepresents an integer of 0 to 3, and m₁, M₂, M_ThreeAnd m_FourIs
It represents an integer of 0 to 3. M is two hydrogen atoms, divalent metal
Atom, trivalent or tetravalent substituted metal atom, or oxygold
Represents a genus. ) Here, having absorption means the imaginary part of the complex refractive index.
The absolute value of (extinction coefficient) is 0.1 or more.
The light transmission amount here is 5 of the wavelength of the laser light used, which is the shortest
Light transmission spectrum in the region from 0 nm short wavelength to 300 nm.
When measuring the cutout, the transmission area on the chart
The ratio (%) to the entire area of the wavelength region is shown.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The specific constitution of the present invention will be described in more detail below. The optical recording medium of the present invention basically has a recording layer containing at least an organic dye and a light reflecting layer on a substrate, and the optical recording medium is a read-only optical reproduction in which information is recorded in advance. It shows both a dedicated medium and an optical recording medium capable of recording and reproducing information. However, a write-once type optical recording medium capable of recording and reproducing the latter information will be described here as a suitable example.

The material of the substrate is basically required to be transparent at the wavelengths of recording light and reproducing light. For example, acrylic resin, polyethylene resin, vinyl chloride resin, polycarbonate resin, polystyrene resin, polyolefin resin,
An organic polymer material such as epoxy resin or an inorganic material such as glass is used. Among these, injection molded substrates of acrylic resin, polycarbonate resin, and polyolefin resin are preferable from the viewpoint of mechanical strength of the substrate, easiness of imparting a guide groove or reproduction-only signal, and economical efficiency, and a polycarbonate resin substrate is particularly preferable. .

The shape of these transparent substrates may be plate-like, film-like, circular or card-like. The surface of these substrates may have a guide groove or a pit indicating a recording position. Such guide grooves and pits are preferably provided at the time of molding the substrate, but they may be provided by providing a thermosetting resin or ultraviolet curing resin layer on the substrate. When normally used as a CD, it has a disk shape with a thickness of about 1.2 mm and a diameter of about 80 to 120 mm, and has a hole with a diameter of about 15 mm in the center.

In the present invention, the organic dye contained in the transparent substrate is preferably one having heat resistance capable of withstanding a high temperature at the time of molding the substrate, compatibility with a resin, and high light resistance. Further, it is preferable to have no absorption in the wavelength region of the recording / reproducing laser light, and particularly to have an absorption region below the wavelength of the laser light having high light energy. In order to suppress the photo-deterioration of the organic dye contained in the recording layer, it is preferable to suppress the light of unnecessary wavelength as much as possible, and the light transmission amount in the wavelength region below the wavelength of the recording / reproducing laser light is 25% or less. When a dye is mixed as described above, it is particularly effective for the photodegradation of the recording layer. The content of the organic dye contained in the transparent substrate may vary depending on the type of the organic dye, but in consideration of the substrate moldability and the compatibility between the resin and the substrate, the dye is usually added in an amount of 0.01 to the total weight of the substrate. The amount of light transmission is appropriately selected within the range of about 1.0 wt.

The method of incorporating the organic dye into the transparent substrate is as follows.
Conventional methods known in the art can be used. For example, resin powder and pigment powder in an appropriate weight ratio are thoroughly stirred and mixed, melted in a temperature range of 150 to 400 ° C. according to the resin, then made into a rod shape having an appropriate diameter with an extruder, and pelletized. Disconnect. By injection molding using this pellet, a transparent substrate containing an organic dye is obtained. At this time, it is possible to add additives such as a release agent and an antioxidant.

As a specific example of the organic dye contained in the substrate, it is preferable to use an anthraquinone dye represented by the formula (1) as a main component. In the formula (1), R ₁ , R ₂ and R
₃ , R ₄ , R ₅ , R ₆ and R ₇ are each independently a hydrogen atom,
Halogen atom, hydroxyl group, carboxyl group, sulfone group, nitro group, cyano group, substituted or unsubstituted alkyl group, alkoxy group, allyl group, aryl group, aryloxy group, alkylthio group, arylthio group, aralkyl group, acyl group , Alkylcarboxyl group, aralkyl group, ester group, carbamoyl group, vinyl group, acylamino group, sulfamoyl group, phenylazo group, pyridinoazo group, alkylcarbonylamino group, alkylsulfonamino group, alkylamino group, arylamino group,
Sulfonamide group, amino group, alkylcarbonyl group,
It represents an alkylsulfone group or a phenyl group, and R ₂ and R ₃ may form a ring via a linking group.

Among these substituents, preferred substituents are
An alkyl group having 1 to 10 carbon atoms which may have a substituent,
Fluoroalkyl group having 1 to 10 carbon atoms, which may have a substituent, alkoxy group having 1 to 10 carbon atoms, which may have a substituent, halogen atom, cyano group, nitro group, hydroxyl group, substituted A phenylazo group which may have a group, a pyridinoazo group which may have a substituent, and a carbon number of 2 to 10
Ester group, C 1-10 sulfonamide group, -N
R ¹ R ² (R ¹ and R ² each independently represent a hydrogen atom, an alkyl group having 1 to 15 carbon atoms which may have a substituent, or a phenyl group which may have a substituent; R ¹ and R ² may together form a 5-membered ring or a 6-membered ring) and the like. The alkyl group moiety may be sulfonated, nitrated, cyanated, halogenated, acetylated, or hydroxylated. R ₂ and R
Examples of the ring via the linking group of ₃ include a substituted or unsubstituted aromatic ring.

Other than the anthraquinone dyes, for example, there are naphthoquinone dyes, azo dyes, quinoline dyes, azomethine dyes, phthalocyanine dyes, polyene dyes, and the like, and it is preferable to use these dyes together with the anthraquinone dyes.

When it is difficult to reduce the amount of light transmitted below the wavelength of the laser light used (on the low wavelength side) to 25% or less with one kind of dye, two or more kinds of dyes having different absorption wavelength regions are mixed. It is preferable. Also, for example, the glass plate is 3
The low wavelength side from around 00 nm is an opaque region, and the polycarbonate resin is an opaque region from around 350 nm to a low wavelength side. Therefore, it suffices to mix the substrate with an organic dye that absorbs light having a wavelength longer than the opaque region of the substrate material. Further, an additive such as an ultraviolet absorber may be mixed.

The recording layer has a suitable absorption mainly in the laser wavelength region and undergoes physical / chemical deformation / irradiation with a laser beam having a certain energy or more accompanied by light / heat conversion.
The substance is not particularly limited as long as it is a substance that undergoes alteration / decomposition, but the present invention mainly contains an organic dye. For example, as a material having effective recording ability, phthalocyanine dyes, naphthalocyanine dyes, cyanine dyes, quinone dyes, porphyrin dyes, tetraazaporphyrin dyes, azo dyes, dithiol metal complex dyes, squarylium dyes Dyes, pyrylium dyes, indophenol dyes, triphenylmethane dyes, xanthene dyes, indanthrene dyes, indigo dyes, oxazine dyes, indoaniline dyes and azulene dyes, etc. A metal may be contained.

Of these, phthalocyanine-based and naphthalocyanine-based dyes are preferable because they are excellent in moist heat resistance and light resistance,
A phthalocyanine dye is particularly preferable in consideration of ease of synthesis. The recording layer may contain the above-mentioned plural dyes.

Particularly preferred phthalocyanine dyes are of the formula
As shown in (2), in the formula, Y ₁, Y₂,
Y_Three, Y_Four, Y_Five, Y₆, Y₇And Y₈Each independently
Hydrogen atom, unsubstituted or substituted hydrocarbon having 1 to 20 carbon atoms
Group, unsubstituted or substituted hydrocarbon oxy having 1 to 20 carbon atoms
Group, unsubstituted or substituted hydrocarbon thio group having 1 to 20 carbon atoms
The hydrocarbon part is methyl, ethyl, butyl, pen
Chill, hexyl, heptyl, octyl, nonyl, decyl
Le, dodecyl, cyclohexyl, dimethylcyclohexyl
Saturated hydrocarbon groups such as ethenyl, butenyl, hexenyl
Le, octenyl, dodecenyl, butynyl, heptynyl,
Phenyl, methylphenyl, butylphenyl, hexyl
An unsaturated hydrocarbon group such as phenyl may be mentioned.

These hydrocarbon moieties may be linear, branched or cyclic. Further, these hydrocarbon moieties may be substituted with halogen, amino group, cyano group, ether group, hydroxyl group and the like. On the other hand, A ₁ , A ₂ , A ₃ and A ₄
Represents a halogen atom such as fluorine, chlorine, bromine or iodine, or a nitro group. The aforementioned Y ₁ to Y ₈ and A _{1 to} A bonded to the benzene ring constituting the phthalocyanine ring.
The substitution position of the substituent of ₄ is not particularly limited, and the kind and number of substituents may be different in the four benzene rings in one molecule.

Examples of the divalent metal atom represented by M include Cu, Zn, Fe, Co, Ni, Ru, Pd and P.
t, Mg, Ti, Be, Ca, Ba, Pb, Cd and the like, and examples of mono-substituted trivalent metals include Al-Cl and A.
l-Br, Ga-Cl, Ga-Br, In-Cl, In
-Br, Ti-Cl, Ti- Br, Al-C 6 H 5, A
_{l-C 6 H 4 (CH} 3), In-C 10 H 7, Mn (O
H), Mn (OC ₆ H ₅ ), Mn [OSi (C
_{H 3) 3], FeCl,} RuCl , etc., as the two substituted tetravalent metal, CrCl _2, SiCl _2, GEB
r ₂ , SnCl ₂ , TiCl ₂ , Mn (OH) ₂ , Sn
(OH) ₂ , TiR ₂ , CrR ₂ , SiR ₂ , Sn
R ₂ , GeR ₂ [R represents an alkyl group, a phenyl group, a naphthyl group and its derivatives], Ti (OR ′) ₂ , Cr
(OR ') ₂ , Si (OR') ₂ , Sn (OR ')
₂ [R 'represents an alkyl group, a phenyl group, a naphthyl group, a trialkylsilyl group, a dialkylalkoxysilyl group and derivatives thereof] and the like, and examples of the oxymetal include VO, MnO, TiO and the like. . Examples of this specific phthalocyanine dye include JP-A-3-62878,
Examples thereof include dyes described in JP-A-3-141582 and JP-A-3-215466, and the dyes can be synthesized by the methods described therein.

If necessary, additives such as a resin, a leveling agent, a quencher, a dye thermal decomposition accelerator, an ultraviolet absorber and an adhesive may be mixed or introduced as a substituent into the recording layer. is there. Examples of the resin and the leveling agent include nitrocellulose, ethyl cellulose, acrylic resin, polystyrene resin, urethane resin and the like.

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. . Amine type is also suitable.

For details of the quencher, see JP-A-59.
-24692, 59-55794, 59-55795, 59-81194
No., 59-83695, 60-18387, 60-19586, 60
-19587, 60-35054, 60-36190, 60-36191
No. 60, No. 60-44554, No. 60-44555, No. 60-44389, No. 60
-44390, 60-47069, 60-20991, 60-71294
No. 60, No. 60-54892, No. 60-71295, No. 60-71296, No. 60
-73891, 60-73892, 60-73893, 60-83892
No. 60, No. 60-85449, No. 60-92893, No. 60-159087, No.
60-162691, 60-203488, 60-201988, 60
-234886, 60-234892, 61-16894, 61-112
No. 92, No. 61-11294, No. 61-16891, No. 61-8384, No. 6
1-14988, 61-163243, 61-210539, 62-30
No. 088, No. 62-32132, No. 62-31792, and "Chemistry of Functional Dyes" (published by CMC, 1981, P74-).

The thermal decomposition accelerator is not particularly limited as long as the promotion of thermal decomposition of the dye can be confirmed by thermal loss analysis (TG analysis). For example, a metal antiknocking agent,
Metal compounds such as metallocene compounds and acetylacetonate-based metal complexes are exemplified.

If desired, various quenchers and dye thermal decomposition accelerators described above may be added with various kinds of additives or additives such as binders.

The content of the dye in this recording layer is 30% or more, preferably 60% or more, and substantially 100%.
That is, it may consist of only the dye. The organic dyes in the recording layer may be used alone or in combination of two or more. Further, different organic dyes may be laminated. The thickness of the recording layer is generally 50 to 300 n.
m.

There are no particular limitations on the method for producing the recording layer, and there are coating methods such as spin coating and casting, sputtering, chemical vapor deposition and vacuum vapor deposition. However,
In the present invention, the coating method is preferable in that the degree of freedom and ease of dye selection, medium design, and manufacturing can be further expanded. The solvent in the coating method is one that easily dissolves or disperses the dye,
Moreover, a material that damages the substrate is preferable. For example,
Alcohol solvent (methanol, ethanol, propanol, etc.), halogenated alcohol solvent (2,2,3,3-tetrafluoro-1-propanol, hexafluoroisopropanol, etc.), hydrocarbon solvent (hexane, cyclohexane, ethylcyclohexane) , Cyclooctane, dimethylcyclohexane, octane, benzene, toluene, xylene, etc.), halogenated hydrocarbon solvents (dichloromethane, chloroform, tetrachlorohydrocarbon, tetrachloroethylene, dichlorodifluoroethane, etc.), ether solvents
(Tetrahydrofuran, diethyl ether, dipropyl ether, dibutyl ether, dioxane, etc.), cellosolve solvent (methyl cellosolve, ethyl cellosolve, etc.)
, A ketone solvent (acetone, cyclohexanone, methyl ethyl ketone, etc.), an ester solvent (ethyl acetate, butyl acetate, etc.), etc. may be used alone or in combination. In addition, an inorganic interference layer, a polymer layer or the like may be provided above and below the recording layer.

In the present invention, as the material of the light reflecting layer,
A material having a sufficiently high reflectance at the wavelength of the reproduction light, such as Au,
Al, Ag, Cu, Ti, Cr, Ni, Pt, Ta, C
It is possible to use the metals of r and Pd alone or as an alloy. Among these, Au and Al have a high reflectance and are suitable as a material for the light reflecting layer. In addition, the following may be included. For example, Mg, Se, Hf,
V, Nb, Ru, W, Mn, Re, Fe, Co, Rh,
Ir, Cu, Zn, Cd, Ga, In, Si, Ge, T
Mention may be made of metals and semi-metals such as e, Pb, Po, Sn and Bi. Further, a material containing Au as a main component is suitable because a light reflecting layer having a high reflectance can be easily obtained. Here, the main component means a component having a content of 50% or more. It is also possible to stack a low refractive index thin film and a high refractive index thin film alternately with a material other than metal to form a multilayer film and use it as a light reflecting layer.

Examples of the method for producing the light reflecting layer include a sputtering method, a chemical vapor deposition method, a vacuum vapor deposition method, an ion plating method and the like, and the film is usually formed to have a film thickness of 30 to 200 nm. It is preferably 50 to 150 nm. Further, a reflection amplification layer and an adhesive layer may be provided between the recording layer and the light reflection layer in order to increase the reflectance and improve the adhesion.

In the present invention, in order to protect the light-reflecting layer, a protective layer which is a conventional method may be further provided on the light-reflecting layer, or two media may be bonded together. The material of the protective layer is not particularly limited as long as it protects the light reflecting layer from external force. Examples of the organic substance include a thermoplastic resin, a thermosetting resin, a UV curable resin, and the like. Among these, the UV curable resin is preferable. Also,
Inorganic substances include SiO ₂ , SiO, SnO ₂ , Si
Examples thereof include N ₄ , MgF ₂ , and AlN. When a thermoplastic resin, a thermosetting resin, or the like is used, the protective layer can be formed by dissolving it in a suitable solvent, applying the coating liquid on the light reflecting layer, and drying. In the case of a UV curable resin, the protective layer can be formed by coating the coating solution as it is or by dissolving it in an appropriate solvent, applying the coating solution, and irradiating and curing the coating solution with UV light. As the UV curable resin, for example, an acrylate resin such as urethane acrylate, epoxy acrylate, polyester acrylate or an epoxy resin can be used. Alternatively, a silicone hard coat resin may 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 for forming the protective layer, the coating method such as spin coating method and casting method, sputtering method, chemical vapor deposition method and the like are used as in the case of the recording layer. Of these, the spin coating method is preferable. The thickness of the protective layer is generally 0.
Although it is in the range of 1 to 100 μm, in the present invention, it is 3 to
A film thickness of 30 μm is preferable.

The optical recording medium of the present invention can be further printed with a label or the like on the protective layer. Further, an ultraviolet curable resin or an inorganic thin film may be formed on the mirror surface side of the substrate to protect the surface and prevent adhesion of dust or the like.

The optical recording medium of the present invention irradiates a laser beam through a substrate to record / reproduce a signal. The laser beam used is usually 620 to 690 nm and 770 to 830 nm.
A semiconductor laser having an oscillation wavelength is preferable.

As a method of recording information on the optical recording medium of the present invention, for example, an optical recording medium is moved at a constant speed (preferably 1 to
While rotating at 15 m / s), the lower part of the guide groove is irradiated with a laser beam from the transparent substrate side to form a reproduction pit in the light absorption layer on the guide groove to record a signal. As the signal, for example, EF of CD standard
The method of recording the M signal is preferable for obtaining the effect of the present invention.

[0041]

EXAMPLES The present invention will be specifically described below with reference to examples, but the embodiments of the present invention are not limited thereto. [Example 1] 15 parts by weight of anthraquinone dye represented by formula (3) [formula 5], 30 parts by weight of anthraquinone dye represented by formula (4) [formula 6] and anthraquinone represented by formula (5) [formula 7] A mixture of 55 parts by weight of the system dye was mixed in the polycarbonate resin so as to be 0.20% by weight to form pellets, and the pellets were formed into continuous guide grooves (depth 130
nm, width 0.5 μm, pitch 1.6 μm), and injection-molded into a disk-shaped substrate having a diameter of 120 mm and a thickness of 1.2 mm. This substrate had a light transmission amount of 18% in the wavelength region of less than 780 nm.

[0042]

Embedded image

[0043]

[Chemical 6]

[0044]

[Chemical 7] A 4 wt% n-octane solution consisting of 20 parts by weight of the phthalocyanine dye represented by the formula (6) and 4 parts by weight of benzoylferrocene was spin-coated on the substrate at a rotation speed of 1600 rpm and dried at 70 ° C. for 3 hours. A recording layer consisting essentially of the dye was formed.

[0045]

Embedded image Next, Au was sputtered on the light absorption layer using a sputtering device (CDI-900) manufactured by Balzers Co., Ltd. to a thickness of 8
A 0 nm light reflection layer was formed. 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. Furthermore, on the light reflection layer, the UV curable resin SD-1
After spin-coating 7 (manufactured by Dainippon Ink and Chemicals),
It was irradiated with ultraviolet rays to form a protective layer having a thickness of 6 μm.

A recording laser power of 8 mW was used to record this optical recording medium with a CD-R writer (Philips, CDD-521) equipped with a 780 nm near infrared semiconductor laser head.
Then, the EFM modulated signal was recorded. Next, the signal was reproduced using a commercially available CD player (YAMAHA, CDX-1050) equipped with a 786 nm near infrared semiconductor laser head. The reflectance is 71%, and the error rate is determined by a Kenwood CD decoder (Kenwood, DR355
It was less than 5 cps when measured using 2), and this medium satisfied the Orange Book standard. As a result of irradiating the substrate surface of this recorded medium with a xenon lamp for 1000 hours, the decrease in reflectance was 5% or less, the error rate was only slightly increased, and deterioration of other recording characteristics was hardly observed. there were.

Example 2 A medium was produced in the same manner as in Example 1 except that the mixing ratio of the dye to the polycarbonate resin was 0.14% by weight. This board is 78
The light transmission amount in the wavelength region of less than 0 nm was 23%. The produced optical recording medium was evaluated for recording and reproduction in the same manner as in Example 1, and as a result, good reflectance and error rate were obtained, which satisfied the Orange Book standard. As a result of irradiating the substrate surface of this recorded medium with a xenon lamp for 1000 hours, the decrease in reflectance was 5% or less, the error rate was only slightly increased, and deterioration of other recording characteristics was hardly observed. there were.

[Example 3] 25 parts by weight of the polyene dye represented by the formula (7) [Chemical formula 9], 16 parts by weight of the anthraquinone dye represented by the formula (8) [Chemical formula 10], and the formula (9) [Chemical formula 11] A mixture of 23 parts by weight of the anthraquinone-based dye shown in (4) and 36 parts by weight of the anthraquinone-based dye represented by the formula 5,
Pellets were made by mixing 0.17% by weight into polycarbonate resin, and the pellets were made into continuous pellets (depth 13
A medium was prepared in the same manner as in Example 1 except that a disk-shaped substrate having a diameter of 120 mm and a thickness of 1.2 mm having a size of 0 nm, a width of 0.5 μm and a pitch of 1.6 μm) was injection molded. In addition,
This substrate had a light transmission amount of 19% in the wavelength region of less than 780 nm.

[0049]

Embedded image

[0050]

Embedded image

[0051]

Embedded image The produced optical recording medium was evaluated for recording and reproduction in the same manner as in Example 1, and as a result, good reflectance and error rate were obtained, which satisfied the Orange Book standard. As a result of irradiating the substrate surface of this recorded medium with a xenon lamp for 1000 hours, the decrease in reflectance was 5% or less, the error rate was only slightly increased, and deterioration of other recording characteristics was hardly observed. there were.

Example 4 45 parts by weight of the anthraquinone dye represented by the formula (10) [formula 12] and the formula (11) [formula 1]
A mixture of 55 parts by weight of the anthraquinone dye shown in 3] was mixed in a polycarbonate resin so as to be 0.15% by weight to form pellets, which were formed into continuous guide grooves (depth 130 nm, width 0. 5 μm, pitch 1.6 μ
m) and a disk-shaped substrate having a diameter of 120 mm and a thickness of 1.2 mm. The substrate had a light transmission amount of 20% in the wavelength region of less than 635 nm.

[0053]

[Chemical 12]

[0054]

Embedded image A 4 wt% 1,2-dimethylcyclohexane solution of a phthalocyanine compound represented by the formula (12) [Chemical Formula 14] was spin-coated on this substrate at a rotation speed of 1600 rpm,
After drying for 3 hours, a recording layer substantially consisting of the dye was formed.

[0055]

Embedded image Furthermore, a 3 wt% 2,2,3,3-tetrafluoro-1-propanol solution of the Ni metal complex of the azo dye represented by the formula (13) [Chemical Formula 15] was spin-coated at a rotation speed of 1600 rpm, and 70
It was dried at ℃ for 3 hours to form a dye layer. The light reflecting layer and the protective layer were formed in the same manner as in Example 1 to prepare a medium.

[0056]

Embedded image This medium is an optical disc evaluation device (DDU-made by Pulstec Industrial Co., Ltd.) equipped with a 680 nm red semiconductor laser head.
1000) and KENWOOD EFM encoder, linear velocity 5.6 m / s, laser power 10 mW
Recorded. After recording, a signal was reproduced at a linear velocity of 1.4 m / s using an evaluation device equipped with a 635 nm red semiconductor laser head. As a result, both reflectance and error rate showed good values. As a result of irradiating the substrate surface of this recorded medium with a xenon lamp for 1000 hours, the decrease in reflectance at 635 nm was small, the error rate was only slightly increased at both wavelengths, and most of the other recording characteristics were not deteriorated. It was not observed and was good.

Comparative Example 1 A medium was prepared in the same manner as in Example 1 except that the substrate was not mixed with an organic dye, and recording / reproduction evaluation and light resistance test were conducted. As a result, the initial characteristics showed good reflectance and error rate, which satisfied the Orange Book standard, but after 1000 hours of irradiation with a xenon lamp, the reflectance was significantly reduced and the error rate increased. Was also great.

[Comparative Example 2] A medium was prepared in the same manner as in Example 1 except that the mixing ratio of the dye to the polycarbonate resin was set to 0.04% by weight, and recording / reproduction evaluation and light resistance test were conducted. . As a result, the initial characteristics showed good reflectance and error rate, and satisfied the Orange Book standard. However, after irradiation with a xenon lamp for 1000 hours,
The reflectance was significantly reduced and the error rate was also greatly increased. The light transmission amount of the substrate was 31%.

[Comparative Example 3] A medium was prepared in the same manner as in Example 4 except that the substrate was not mixed with an organic dye, and recording / reproduction evaluation and light resistance test were conducted. As a result, good reflectance and error rate were obtained as initial characteristics, but after 1000 hours of irradiation with a xenon lamp, the reflectance was significantly reduced and the error rate was significantly increased at 635 nm. The reflectance and error rate in Examples 1 to 4 and Comparative Examples 1 to 3 at the initial stage and after 1000 hours of irradiation with the xenon lamp are collectively shown in [Table 1].

[0060]

[Table 1]

[0061]

INDUSTRIAL APPLICABILITY In an optical recording medium having an organic recording layer, by containing a specific organic dye in an appropriate ratio in a transparent substrate, it is possible to prevent the deterioration of the recording layer against light and to endure long-term storage. An optical recording medium with high reliability has been made possible.

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

Claims (4)

[Claims] 1. A recording layer containing an organic dye, which is provided on a transparent substrate directly or via another layer, and a light-reflecting layer provided on the recording layer directly or via another layer. At least an optical recording medium comprising the transparent substrate containing an organic dye and having a light transmission amount of 25% or less in a wavelength region shorter than the wavelength of the laser light used. 2. The optical recording medium according to claim 1, wherein the organic dye contained in the transparent substrate is an anthraquinone dye having an absorption of 750 nm or less represented by the formula (1) [Chemical Formula 1]. Embedded image (In the formula, R ₁ , R ₂ , R ₃ , R ₄ , R ₅ , R ₆ , R ₇ and R ₈ are each independently a hydrogen atom, a halogen atom, a hydroxyl group, a carboxyl group, a sulfone group, a nitro group or a cyano group. Group, substituted or unsubstituted alkyl group, alkoxy group,
Allyl group, aryl group, aryloxy group, alkylthio group, arylthio group, aralkyl group, acyl group, alkylcarboxyl group, aralkyl group, ester group, carbamoyl group, vinyl group, acylamino group, sulfamoyl group, phenylazo group, pyridinoazo group, It represents an alkylcarbonylamino group, an alkylsulfonamino group, an alkylamino group, an arylamino group, a sulfonamide group, an amino group, an alkylcarbonyl group, an alkylsulfone group or a phenyl group, and R ₂ and R ₃ are cyclic groups via a linking group. May be formed. ) 3. The optical recording medium according to claim 1, wherein the transparent substrate contains polycarbonate as a main component. 4. The recording layer is represented by the formula (2)
Any of claims 1 to 3 containing a tarocyanine dye as a main component.
An optical recording medium described therein. [Chemical 2](In the formula, Y₁, Y₂, Y_Three, Y_Four, Y_Five, Y₆, Y₇Over
And Y₈Are each independently an unsubstituted or substituted group having 1 to 20 carbon atoms.
Substituted hydrocarbon group, unsubstituted or substituted carbonization having 1 to 20 carbon atoms
Hydrogen oxy group, unsubstituted or substituted carbonization having 1 to 20 carbon atoms
Represents a hydrogen thio group, Y₁And Y₂, Y_ThreeAnd Y_Four, Y_FiveAnd Y
₆, And Y₇And Y₈Next to each other in each combination of
When they are in contact with each other, the groups that may be connected to form a ring are shown.
You. On the other hand, A ₁, A₂, A_ThreeAnd A_FourEach independently
Represents a rogen atom and a nitro group. l₁, L₂, L_ThreeAnd l
_FourRepresents an integer of 0 to 3, and m₁, M₂, M_ThreeAnd m_FourIs
It represents an integer of 0 to 3. M is two hydrogen atoms, divalent metal
Atom, trivalent or tetravalent substituted metal atom, or oxygold
Represents a genus. )