JPH11334207A - Optical recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To deal with a blue laser beam by incorporating a porphyrin compound represented by a specific formula in a record layer. SOLUTION: The optical recording medium comprises a substrate and a record layer containing a porphyrin compound represented by a specific formula. As the substrate, a material which is transparent to a laser beam is preferable, and a glass or a plastic is used. In the formula representing the porphyrion compound, as each of substitutents represented by R<1> to R<4> , a hydrogen atom, an alkyl group such as a methyl group, ethyl group, n-propyl group or the like is used, as each of substituents represented by X<1> to X<8> , a hydrogen atom, an alkyl group such as a methyl group, ethyl group, n-propyl group, isopropyl group or the like, alkoxy group, alkylcarbonyl group or the like is used, wherein all of the X<1> to X<8> do not become a non-substituted alkyl groups. Further, as M, a hydrogen atom or a metal atom is used. Thus, a light resistance and a heat resistance can be improved at low cost.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an optical recording medium for a blue laser using a porphyrin compound for a recording layer.

[0002]

2. Description of the Related Art In recent years, optical recording using a laser has been particularly developed in order to enable high-density information recording and storage and reproduction thereof.

An example of such an optical recording medium is an optical disk.

In general, an optical disc performs high-density information recording by irradiating a thin recording layer provided on a circular base with a laser beam converged to about 1 μm. Among them, a writable compact disc (CD-R) has recently attracted attention. A CD-R is generally formed by sequentially stacking a recording layer mainly composed of a dye, a metal reflective film, and a protective film on a plastic substrate having a guide groove. Recording of information is performed by the absorption of the irradiated laser light energy, whereby thermal deformation such as decomposition, evaporation, or dissolution is generated in the recording layer, the reflective layer, or the substrate at that location. Reproduction of recorded information is performed by reading a difference in reflectance between a portion where deformation has occurred and a portion where no deformation has occurred due to laser light. Accordingly, it is necessary to efficiently absorb the energy of laser light as an optical recording medium, and a laser absorbing dye is used.

[0005] Optical recording media utilizing organic dyes as laser absorbing dyes are expected to become more and more popular as inexpensive optical recording media because the recording layer can be formed by a simple method by applying an organic dye solution. As a result, higher densification is demanded. For this reason,
It has been studied to shorten the wavelength of a laser beam used for recording from a conventional semiconductor laser centered at 780 nm to a blue light region.

Conventionally, as an optical recording medium which can be recorded and reproduced by a blue laser, a porphyrin-based compound in which all the substituents introduced into the porphine nucleus are ethyl groups, such as M The use of octaethylporphine, which is Pb, has been proposed (JP-A-8-127174).

[0007]

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(Where M represents any one of Pb, BiO and ReO, X and Y are phenoxy groups, NO ₂ , Cl, B
r, I, ClO ₄ , or BF ₄ . )

[0009]

Problems to be Solved by the Invention
An optical recording medium using a porphyrin-based compound described in Japanese Patent Publication No. 4 can be used for recording and reproduction with a blue laser. At present, development is desired.

The present invention has been made in view of the above-mentioned conventional circumstances, and has as its object to provide an optical recording medium compatible with a blue laser using a porphyrin compound for a recording layer.

[0011]

An optical recording medium according to the present invention is an optical recording medium having a recording layer on a substrate on which information can be written and / or read by a laser. It is characterized by containing the porphyrin compound represented by [I].

[0012]

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(Wherein R ¹ , R ² , R ³ and R ⁴ represent a hydrogen atom or an alkyl group, and X ¹ , X ² , X ³ , X ⁴ ,
X ⁵ , X ⁶ , X ⁷ and X ⁸ each independently represent a hydrogen atom, an alkyl group, an alkoxy group, an alkylcarbonyl group, an alkenyl group, a halogen atom, a hydroxyl group, a carboxyl group, a hydroxyalkyl group, a carboxylalkyl group,
Alkoxycarbonyl group, alkylcarbonyloxy group, nitro group, cyano group, formyl group, sulfonic acid group,
Alkoxyalkyl group, alkoxycarbonylalkyl group, alkylthio group, alkylsulfonyl group, -NR ⁹
R ¹⁰ , —CONR ⁹ R ¹⁰ (R ⁹ and R ¹⁰ each independently represent a hydrogen atom, an alkyl group, an alkenyl group, an aryl group, an aralkyl group, an alkoxyalkyl group, an alkylcarbonyl group, or a hydroxyalkyl group. , R ⁹ and R ¹⁰ may be bonded to each other, or may be bonded to a ring substituted with an amino group or an amide group to form a ring.), A fluoroalkyl group, a fluoroalkoxy group, and a fluoroalkylthio group; Represents a hydrogen atom or a metal atom. However, all of X ^{1 to} X ⁸ do not become unsubstituted alkyl groups. That is, the inventors of the present invention have conducted intensive studies to achieve the above object, and as a result, a porphyrin-based compound described in JP-A-8-127174, in which all the substituents introduced into the porphine nucleus are ethyl groups, is disclosed. The present inventors have found that an optical recording medium using a porphyrin compound represented by the above general formula [I] for a recording layer can be satisfactorily recorded with a blue laser, and completed the present invention.

The porphyrin compound according to the present invention has a large molar extinction coefficient in the blue light region having a wavelength of 350 to 530 nm, has a sharp absorption (Soret band), and is suitable for recording with a blue laser. In addition, since synthesis is relatively easy among porphyrin-based compounds, an inexpensive optical recording medium can be provided. Further, it has high light stability and heat resistance, and is suitable for an optical recording medium requiring stability.

[0015]

Embodiments of the present invention will be described below in detail.

In the general formula [I] representing the porphyrin compound according to the present invention, the substituent represented by R ^{1 to} R ⁴ is a hydrogen atom; a methyl group, an ethyl group, an n-propyl group or an isopropyl group. , A n-butyl group, a tert-butyl group, a sec-butyl group, an n-pentyl group, an n-hexyl group and the like.

In the general formula [I], X¹~
X⁸A hydrogen atom; a methyl group;
Tyl group, n-propyl group, isopropyl group, n-butyl
Group, tert-butyl group, sec-butyl group, n-pen
A C 1-20 linear chain such as a tyl group, an n-hexyl group, or
Branched alkyl group; cyclopropyl group, cyclobutyl
3 carbon atoms such as a group, cyclopentyl group and cyclohexyl group
A cyclic alkyl group of 10 to 10; a methoxy group, an ethoxy group,
n-propoxy group, isopropoxy group, n-butoxy
Group, tert-butoxy group, sec-butoxy group, n-
1 carbon atom such as a pentyloxy group or an n-hexyloxy group
-20 linear or branched alkoxy groups;
Lopionyl, butyryl, isobutyryl, valeryl
Group, isovaleryl group, pivaloyl group, hexanoyl group,
A straight or branched chain having 2 to 21 carbon atoms such as a heptanoyl group.
Alkylcarbonyl group; vinyl group, propenyl group, buteni
, A pentenyl group, a hexenyl group, etc.
A linear or branched alkenyl group; a cyclopentenyl group,
C3-C10 cyclic alky such as cyclohexenyl group
Nyl group; halogen such as fluorine atom, chlorine atom and bromine atom
Atom; hydroxyl group; carboxyl group;
C1-20 hydrides such as tyl and hydroxyethyl groups
Roxyalkyl group; carboxylmethyl group, 2-carbo
Carbon such as xylethyl group and 3-carboxylpropyl group
A linear or branched carboxylalkyl group of the formulas 1 to 20;
Methoxycarbonyl group, ethoxycarbonyl group, n-propyl
Ropoxycarbonyl group, isopropoxycarbonyl group,
n-butoxycarbonyl group, tert-butoxycarbo
Nil group, sec-butoxycarbonyl group, n-pentyl
Oxycarbonyl group, n-hexyloxycarbonyl group
Linear or branched alkoxycarbo having 2 to 21 carbon atoms, such as
Nyl group; methylcarbonyloxy group, ethylcarbonyl
Oxy group, n-propylcarbonyloxy group, isopro
Pillcarbonyloxy group, n-butylcarbonyloxy
Group, tert-butylcarbonyloxy group, sec-butyl
Tylcarbonyloxy group, n-pentylcarbonyloxy
C 2, such as n-hexylcarbonyloxy group
21 linear or branched alkylcarbonyloxy groups;
Toro group; cyano group; formyl group; sulfonic acid group;
Cimethyl group, methoxyethyl group, ethoxymethyl group,
Toxylethyl group, n-propoxyethyl group, n-propoxy
Xypropyl group, isopropoxymethyl group, isopropo
A linear or branched alkyl having 2 to 21 carbon atoms such as a xylethyl group;
Coxyalkyl group; methoxycarbonylmethyl group, methoxy
Xycarbonylethyl group, ethoxycarbonylmethyl
Group, ethoxycarbonylethyl group, n-propoxycal
Bonylethyl group, n-propoxycarbonylpropyl
Group, isopropoxycarbonylmethyl group, isopropoxy
A straight or branched chain having 3 to 22 carbon atoms such as a cyclocarbonylethyl group
Various alkoxycarbonylalkyl groups; methylthio groups,
Ethylthio group, n-propylthio group, isopropylthio
Group, n-butylthio group, tert-butylthio group, se
c-butylthio group, n-pentylthio group, n-hexyl
C1-C20 linear or branched alkylthio such as thio group
E group: methylsulfonyl group, ethylsulfonyl group, n-
Propylsulfonyl group, isopropylsulfonyl group, n
-Butylsulfonyl group, tert-butylsulfonyl
Group, sec-butylsulfonyl group, n-pentylsulfo group
1-20 carbon atoms such as a nyl group and an n-hexylsulfonyl group
A linear or branched alkylsulfonyl group;⁹R^Ten
(R⁹, R^TenAre each independently a hydrogen atom, a carbon number of 1 to
12 straight-chain or branched alkyl groups having 2 to 12 carbon atoms
May have a chain or branched alkenyl group, a substituent
An aryl group such as a phenyl group, a straight chain having 7 to 20 carbon atoms, or
Branched aralkyl groups, straight-chain or branched having 2 to 12 carbon atoms
Alkoxyalkyl group, linear or branched having 2 to 12 carbon atoms
Alkylcarbonyl group; linear or branched having 1 to 12 carbon atoms
Represents a hydroxyalkyl group. Also, R⁹ And R^TenIs
Linked to each other or to a ring substituted with an amino group
To form a ring. ); -CONR⁹R^Ten(R⁹,
R^TenIs the same as above. ); A trifluoromethyl group,
Pentafluoroethyl group, heptafluoro-n-propyl
Group, heptafluoroisopropyl group, perfluoro-
n-butyl group, perfluoro-tert-butyl group,
-Fluoro-sec-butyl group, perfluoro-n-pe
1 carbon atom such as an ethyl group or a perfluoro-n-hexyl group
To 20 linear or branched fluoroalkyl groups;
Oromethoxy group, pentafluoroethoxy group, heptaph
Fluoro-n-propoxy group, heptafluoroisopropo
Xy group, perfluoro-n-butoxy group, perfluoro
-Tert-butoxy group, perfluoro-sec-buto
Xy group, perfluoro-n-pentyloxy group, perf
A straight-chain having 1 to 20 carbon atoms such as a fluoro-n-hexyloxy group.
Chain or branched fluoroalkoxy group; trifluoromethyl
Luthio group, pentafluoroethylthio group, heptafluor
B-n-propylthio group, heptafluoroisopropyl
Thio group, perfluoro-n-butylthio group, perfluoro
Low-tert-butylthio group, perfluoro-sec-
Butylthio group, perfluoro-n-pentylthio group,
1 to 20 carbon atoms such as -fluoro-n-hexylthio group
A linear or branched fluoroalkylthio group is exemplified.
Where X ¹~ X⁸Are all unsubstituted alkyl groups
Never.

In the general formula [I], M is a hydrogen atom or a metal atom. As metal atoms, Mg, Al, Si, Ca, Sc, Ti, V, Cr,
Mn, Fe, Co, Ni, Cu, Zn, Ga, Ge, A
s, Sr, Y, Zr, Nb, Mo, Tc, Ru, Rh,
Pd, Ag, Cd, In, Sn, Sb, Ba, Pr, E
u, Yb, Hf, Ta, W, Re, Os, Ir, Pt,
Generally, any metal such as Au, Hg, Tl, Pb, Bi, and Th, which can coordinate to a porphyrin-based compound, may be used. There is no particular limitation, but Mg, Al, Si, Ti, V,
Mn, Fe, Co, Ni, Cu, Zn, Ga, Ge, P
d, in, Sn, Pb and the like are preferable. M is Fe,
In the case of metals such as In and Sn, F ⁻ , C
l ^-, Br ^{- -,} I and halogen ions; OR ^-, OP
_{^{h -, NCS -, N 3}} -, OH -, CN -, CH 3 COO -, C
Anions such as F ₃ COO ⁻ , BF ₄ ⁻ , PF ₆ ⁻ , ClO ₄ ⁻ and p-toluenesulfonic acid ion represented by the following structural formula;
Bases such as pyridine and imidazole; gases such as NO, CO and O ₂ ; which may have water (where R is methyl, ethyl, n-propyl, isopropyl, n-
Butyl group, tert-butyl group, sec-butyl group, n
-Represents a linear or branched alkyl group having 1 to 10 carbon atoms such as a pentyl group and an n-hexyl group, and Ph represents a phenyl group which may have a substituent. ).

[0019]

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The porphyrin compound of the present invention specifically has the following structure.

[0021]

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[0022]

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[0023]

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[0024]

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[0025]

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[0026]

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[0027]

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These porphyrin compounds may be used singly or as a mixture of two or more.

Such a porphyrin compound can be synthesized by a known method using a pyrrole derivative as a raw material. Alternatively, it can be synthesized using naturally occurring heme as a starting material.

The introduction of the central metal is accomplished by converting a metal-free porphyrin compound to acetic acid, N, N-dimethylformamide,
It can be carried out by heating with a metal salt such as a halide, an acetate, a metal acetylacetonate complex or a metal carbonyl complex in an organic solvent such as benzene, ether, chloroform or pyridine.

Although the optical recording medium of the present invention basically comprises a substrate and a recording layer containing the porphyrin compound, an undercoat layer may be further provided on the substrate if necessary. it can.

The substrate is preferably transparent to the laser beam used, and glass and various plastics are used. Examples of the plastic include acrylic resin, methacrylic resin, polycarbonate resin, vinyl chloride resin, vinyl acetate resin, nitrocellulose, polyester resin, polyethylene resin, polypropylene resin, polyimide resin, polystyrene resin, epoxy resin, etc. Injection molded polycarbonate resin substrates are particularly preferred from the viewpoints of cost, moisture absorption resistance and the like.

The recording layer containing a porphyrin compound in the optical recording medium of the present invention generally has a thickness of 100 °.
５5 μm, preferably 700Å-3 μm.

The recording layer is formed by a vacuum evaporation method, a sputtering method, a doctor blade method, a casting method, a spinner method,
Although a film can be formed by a generally used thin film forming method such as an immersion method, a spinner method is preferable in terms of mass productivity and cost.

In forming the recording layer, a binder can be used if necessary. Known binders such as polyvinyl alcohol, polyvinyl pyrrolidone, ketone resin, nitrocellulose, cellulose acetate, polyvinyl butyral, and polycarbonate are used as the binder. In this case, the porphyrin compound according to the present invention is:
It is preferable that the content is 10% by weight or more in the binder resin.

In the case of film formation by the spinner method, the number of rotations is 5
00-5000 rpm is preferable, and after spin coating,
In some cases, treatment such as heating or exposure to solvent vapor may be performed.

In order to improve the stability and light resistance of the recording layer, a transition metal chelate compound (eg, acetylacetonate chelate, bisphenyldithiol, salicylaldehyde oxime, bisdithio-α-diketone, etc.) is used as a singlet oxygen quencher. And the like, and a recording sensitivity improver such as a metal-based compound for improving the recording sensitivity. Here, the metal compound refers to a compound in which a metal such as a transition metal is included in the compound in the form of an atom, an ion, a cluster, or the like. And organic metal compounds such as dihydroxyazobenzene-based complexes, dioxime-based complexes, nitrosoaminophenol-based complexes, pyridyltriazine-based complexes, acetylacetonate-based complexes, metallocene-based complexes, and porphyrin-based complexes. The metal atom is not particularly limited, but is preferably a transition metal.

As the metal, other dyes can be used in combination, if necessary. Other types of dyes mainly absorb in the laser wavelength range for recording, and absorb the irradiated laser light energy to cause heat, such as decomposition, evaporation, and dissolution, on the recording layer, reflective layer, or substrate at that location. There is no particular limitation as long as pits are formed along with the mechanical deformation. In addition, 770 to 830 nm like CD-R
Optics compatible with recording with lasers in multiple wavelength ranges by using a dye suitable for recording with a near-infrared laser of a wavelength selected from among the above or a red laser selected from 620 to 690 nm such as DVD-R. It can also be a recording medium. As other types of dyes, specifically, metal-containing azo dyes,
Phthalocyanine dye, naphthalocyanine dye, cyanine dye, azo dye, squarylium dye, metal-containing indoaniline dye, triarylmethane dye,
Examples include merocyanine dyes, azulenium dyes, naphthoquinone dyes, anthraquinone dyes, indophenol dyes, xanthene dyes, oxazine dyes, and pyrylium dyes.

The coating solvent for forming the recording layer by a coating method such as a doctor blade method, a casting method, a spinner method, an immersion method, particularly a spinner method, may be any solvent which does not attack the substrate, and is not particularly limited. For example, ketone alcohol solvents such as diacetone alcohol and 3-hydroxy-3-methyl-2-butanone, cellosolve solvents such as methyl cellosolve and ethyl cellosolve, hydrocarbon solvents such as n-hexane and n-octane, cyclohexane , Methylcyclohexane, ethylcyclohexane, dimethylcyclohexane, n-butylcyclohexane, t
Hydrocarbon solvents such as butylcyclohexane and cyclooctane; ether solvents such as diisopropyl ether and dibutyl ether; perfluoroalkyl alcohol solvents such as tetrafluoropropanol, octafluoropentanol and hexafluorobutanol; methyl lactate and ethyl lactate And hydroxyester solvents such as methyl isobutyrate.

Further, a metal reflective layer such as gold, silver, aluminum or an alloy thereof and a protective layer may be provided on the recording layer to provide a medium having high reflectance. In this case, the reflective layer may be made of gold, silver, aluminum, or the like. However, with gold or aluminum, the reflectivity of the laser light having a wavelength of 530 nm or less used in the present invention is not sufficient, and silver is preferable.

The metal reflection layer is formed by a vapor deposition method, a sputtering method, or an ion plating method. Note that an intermediate layer may be provided between the metal reflective layer and the recording layer for the purpose of improving the adhesion between the layers or for the purpose of increasing the reflectance.

As the protective layer, for example, an ultraviolet curable resin composition may be used.

The optical recording medium may be bonded to both sides by an adhesive layer to form a double-sided recording type optical recording medium, or the recording layer may be provided on both sides of the substrate, or may be provided on one side.

The laser beam used for the optical recording medium of the present invention is preferably shorter in wavelength for high adhesion recording, but a laser beam of 350 nm to 530 nm is particularly preferable. A typical example of such a laser is a center wavelength 410
nm, 515 nm laser.

The laser light having a wavelength in the range of 350 nm to 530 nm can be obtained, for example, by using a high-power semiconductor laser of blue of 410 nm or blue-green of 515 nm. Is either a semiconductor laser capable of continuous oscillation of 740 to 960 nm or (b) a solid laser capable of continuous oscillation having a fundamental oscillation wavelength of 740 to 960 nm which is excited by a semiconductor laser. It can also be obtained by conversion.

The SHG may be any piezo element that does not have reflection symmetry.
ADP, BNN, KN, LBO, compound semiconductor, and the like are preferable. As a specific example of the second harmonic, in the case of a semiconductor laser having a fundamental oscillation wavelength of 860 nm, 43
In the case of a solid-state laser excited by a semiconductor laser, for example, a harmonic of 430 nm from a Cr-doped LiSrAlF ₆ crystal (fundamental oscillation wavelength: 860 nm) may be used.

The recording on the optical recording medium obtained as described above is performed on a recording layer provided on both sides or one side of the substrate by 0.4 to 0.4.
This is performed by applying a laser beam focused to about 0.6 μm. As a result, the part irradiated with the laser light will have decomposition, heat generation,
Thermal deformation of the recording layer such as melting occurs.

The reproduction of the recorded information is performed by reading the difference in reflectance between the portion where the thermal deformation has occurred and the portion where the thermal deformation has not occurred using a laser beam.

[0049]

EXAMPLES The present invention will be described more specifically with reference to the following examples, but the present invention is not limited to the following examples unless it exceeds the gist.

Example 1 (a) Production Example 50 nl of dimethylformamide was heated under reflux with stirring.
Protoporphyrin IX dimethyl ester 0.52 g
(0.88 mmol) was added. After stirring for 10 minutes, F
0.44 g (2.2 mmol) of eCl ₂ .4H ₂ O was added, and the mixture was further stirred for 10 minutes. After allowing to cool, the mixture was poured into water, and the precipitated crystals were separated by filtration and purified by a silica gel column. As a result, 0.46 g (yield: 76.9%) of the porphyrin compound represented by the above structural formula [19] was obtained. .

The maximum absorption wavelength (λmax) of this compound in chloroform was 394 nm, and the molecular extinction coefficient (ε) was 8.3 × 10 ⁴ .

(B) Example of Recording Medium A 1.0% by weight solution of the porphyrin compound obtained above in octafluoropentanol was prepared and filtered to obtain a solution. This solution is 120 mm in diameter and 1.2 m in thickness.
m, was dropped on an injection-molded polycarbonate resin substrate, applied by a spinner method, and then dried at 100 ° C. for 30 minutes. The maximum absorption wavelength (λmax) of this coating film is 39.
It was 5 nm. Fig. 1 shows the absorption spectrum of the visible region of the coating film.
Shown in

Next, a silver film having a thickness of 1000 ° was formed on the coating film by a sputtering method to form a reflection layer. Further, an ultraviolet-curable resin is spin-coated on the reflective layer, and the resin is cured by irradiating ultraviolet rays to a thickness of 5 nm.
A protective layer having a thickness of μm was formed.

The reflectance of the obtained optical recording medium at 488 nm was 55%.

(C) Optical Recording Method When the above-mentioned optical recording medium was irradiated with argon laser light having a center wavelength of 488 nm, good recording pits could be formed.

Example 2 (a) Production Example 50 ml of dimethylformamide was heated to reflux while stirring,
Mesoporphyrin IX dimethyl ester 0.38 g
(0.63 mmol) was added. After stirring for 10 minutes, F
0.31 g (1.6 mmol) of eCl ₂ .4H ₂ O was added, and the mixture was further stirred for 10 minutes. After allowing to cool, the mixture was poured into water, and the precipitated crystals were separated by filtration and purified by a silica gel column. As a result, 0.087 g (yield: 20.2%) of the porphyrin compound represented by the above structural formula [20] was obtained. .

Λmax of this compound in chloroform
Was 378 nm and ε was 9.0 × 10 ⁴ .

(B) Example of Recording Medium A 1.0% by weight solution of the porphyrin compound obtained above in octafluoropentanol was prepared and filtered to obtain a solution. This solution is 120 mm in diameter and 1.2 m in thickness.
m, was dropped on an injection-molded polycarbonate resin substrate, applied by a spinner method, and then dried at 100 ° C. for 30 minutes. Λmax of this coating film was 375 nm.
FIG. 2 shows the absorption spectrum of the visible region of the coating film.

Next, a silver film having a thickness of 1000 ° was formed on the coating film by a sputtering method to form a reflection layer. Further, an ultraviolet-curable resin is spin-coated on the reflective layer, and the resin is cured by irradiating ultraviolet rays to a thickness of 5 nm.
A protective layer having a thickness of μm was formed.

The reflectance of the obtained optical recording medium at 488 nm was 52%.

(C) Optical Recording Method When the above-mentioned optical recording medium was irradiated with argon laser light having a center wavelength of 488 nm, good recording pits could be formed.

Examples 3 and 4 Porphyrin-based compounds represented by the structural formulas [3] (Example 3) and [1] (Example 4) were synthesized. The λmax and ε of this compound were as shown in Table 1.

The porphyrin-based compound was coated on a substrate in the same manner as in Example 1 to produce an optical recording medium having the maximum absorption wavelength of the coating film shown in Table 1.

The obtained optical recording medium has a center wavelength of 488.
When recording was performed using an argon laser of nm.
Good recording pits could be formed.

[0065]

[Table 1]

[0066]

As described in detail above, according to the optical recording medium using the porphyrin compound of the present invention, a high-density recording medium which is inexpensive and has excellent light resistance and heat resistance can be provided.

[Brief description of the drawings]

FIG. 1 is a diagram showing an absorption spectrum of a coating film of a porphyrin compound obtained in Example 1 on a polycarbonate substrate.

FIG. 2 is a diagram showing an absorption spectrum of a coating film of a porphyrin compound obtained in Example 2 on a polycarbonate substrate.

Claims (2)

[Claims] 1. An optical recording medium having a recording layer on which information can be written and / or read by a laser on a substrate, wherein the recording layer contains a porphyrin compound represented by the following general formula [I]. An optical recording medium characterized by the above-mentioned. Embedded image (In the formula [I], R ¹ , R ² , R ³ and R ⁴ represent a hydrogen atom or an alkyl group, and X ¹ , X ² , X ³ , X ⁴ , X ⁵ , X ⁶ , X ⁷ ,
X ⁸ is each independently a hydrogen atom, an alkyl group, an alkoxy group, an alkylcarbonyl group, an alkenyl group, a halogen atom, a hydroxyl group, a carboxyl group, a hydroxyalkyl group, a carboxylalkyl group, an alkoxycarbonyl group, an alkylcarbonyloxy group, a nitro group. group, a cyano group, a formyl group, a sulfonic acid group, an alkoxyalkyl group, an alkoxycarbonylalkyl group, an alkylthio group, an alkylsulfonyl group, -NR ⁹ R ^10, -CONR ⁹
R ¹⁰ (R ⁹ and R ¹⁰ each independently represent a hydrogen atom, an alkyl group, an alkenyl group, an aryl group, an aralkyl group, an alkoxyalkyl group, an alkylcarbonyl group, or a hydroxyalkyl group; and R ⁹ and R ¹⁰ May be bonded to each other, or may be bonded to a ring substituted with an amino group or an amide group to form a ring.), A fluoroalkyl group, a fluoroalkoxy group, and a fluoroalkylthio group;
Represents a hydrogen atom or a metal atom. However, all of X ^{1 to} X ⁸ do not become unsubstituted alkyl groups. ) 2. The optical recording medium according to claim 1, wherein the laser wavelengths for writing and reading are both 350 to 530 nm.