JP3166325B2 - Optical recording medium using azulene compound - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel azulene compound and an organic dye-based optical recording medium using the azulene compound as a laser absorbing dye, and more particularly to the solubility of the laser absorbing dye and the preservation of a coating film. The present invention relates to an organic dye-based optical recording medium having excellent stability.

[0002]

2. Description of the Related Art An example of an optical recording medium is an optical disk. In particular, it is small and highly reliable,
With the advent of inexpensive semiconductor lasers, read-only optical disks such as compact disks (CDs) and the like, and additional optical disks using Te-based inorganic materials as recording media have been put to practical use.

On the other hand, studies have been made on an organic dye-based optical disk using a laser absorbing dye as a new write-once medium. The greatest feature of this organic dye-based optical disk is that it can be formed by a coating method such as a spin coating method, and high productivity under normal pressure is expected to reduce the cost in the future. Generally, an optical disc performs high-density information recording by irradiating a thin recording layer provided on a circular substrate with a laser beam focused to about 1 μm. In the recording layer, recording is performed by thermal deformation such as decomposition, evaporation, and dissolution of the recording layer generated at that location due to absorption of the irradiated laser energy,
Reproduction of recorded information is performed by reading the difference in reflectance between a portion where deformation has occurred and a portion where no deformation has occurred using a laser beam. In addition, guide grooves are formed in advance on the recording surface of the optical disc in order to perform accurate recording / reproduction.

[0004] Usually, the guide groove is formed by a photopolymer method or an injection molding method. However, in the former case, there is a drawback that the productivity is low and the cost is high due to molding from the photopolymer. In the latter case, the injection molding method provides excellent productivity and inexpensive disks can be produced.However, resins that can be used in the injection molding method are required to have fluidity at the time of heating, so there are restrictions on materials, and in general the resin is resistant. Poor solvent properties.

Further, when forming a thin film of a laser-absorbing dye on such an injection-molded plastic substrate by applying a solution, it is necessary that the guide groove on the substrate is not affected by the coating solvent. Are known alcohol solvents. However, few laser-absorbing dyes dissolve in alcohol-based solvents at high concentrations.There are few dyes that can carry stable laser-absorbing dyes on injection-molded plastic substrates and form stable coatings. It has not been.

[0006]

Therefore, the present inventors can apply evenly without invading the injection-molded plastic substrate, dissolve and carry the laser absorbing dye at a high concentration,
In addition, as a result of intensive studies on a method for improving the storage stability of the coating film, it has been found that good performance can be obtained by using a specific novel azulene compound, and the present invention has been achieved.

[0007]

SUMMARY OF THE INVENTION The present invention provides an optical recording medium obtained by applying a novel azulene compound represented by the following general formula [I] and a solution of a laser absorbing dye in an organic solvent onto a substrate and then drying. , Wherein a novel azulene compound represented by the following general formula [I] is used as the laser-absorbing dye.

[0008]

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Wherein R ¹ , R ² , R ³ , R ⁴ , R ⁵ ,
R ⁶ , R ⁷ and R ⁸ each independently represent a hydrogen atom or an alkyl group, and X ⁻ represents an anion. Hereinafter, the present invention will be described in detail. In the general formula [I], R ^{1 to} R ⁸ each independently represent a hydrogen atom or an alkyl group, and the alkyl group preferably has 1 carbon atom.
To 6 alkyl groups.

[0010] In the general formula [I], X ^- as an anion represented by is preferably

[0011]

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And the like. Next, major specific examples of the azulene-based compound represented by the general formula [I] are shown in Tables 1 and 2, but are not limited thereto.

[0013]

[Table 1]

[0014]

[Table 2]

The laser absorbing dye represented by the above general formula [I] can be synthesized, for example, by the following method.

[0016]

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[0017]

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(Wherein, R and R ′ each independently represent a hydrogen atom or an alkyl group, and R ^{1 to} R ⁸ have the same meanings as in the general formula [I].) The optical recording medium of the present invention can be produced by spin-coating on a substrate an azulene-based compound to be used as a laser-absorbing dye and dissolving the azulene-based dye in an alcohol solvent together with the binder as it is or with a binder. Alternatively, other dyes may be mixed and used as the laser absorbing dye.

Any binder can be used as long as it is soluble in an alcohol solvent. The ratio of the laser absorbing dye to the alcohol solvent is 0.5
-3.0% by weight is particularly preferred. The ratio of the laser absorbing dye to the binder is desirably 10% by weight or more. Preferred alcohol solvents include ketone alcohol solvents such as diacetone alcohol and 3-hydroxy-3-methyl-2-butanone; cellsolve solvents such as methylcellsolve and ethylcellsolve; tetrafluoropropanol and octafluoropentanol Perfluoroalkyl alcohol solvents; hydroxyester solvents such as methyl lactate and methyl isobutyrate.

The solution in which the laser absorbing dye is dissolved is 0.1%.
It is preferable to filter with a filter of 3 μm or less. The rotation speed of the spin coating is preferably from 500 to 2000 rpm. After the spin coating, if necessary, a treatment such as heating or exposure to a solvent vapor may be performed. Further, the thickness of the coating film is preferably 300 to 1500 °.

Further, in order to improve the stability and light resistance of the recording medium, a transition metal chelate compound (acetylacetonate chelate, bisphenyldithiol, salicylaldehyde oxime, bisdithio-
α-diketone). The recording layer of the optical recording medium of the present invention may be provided on both sides of the substrate, or may be provided only on one side.

The substrate used in the present invention may be a transparent substrate such as glass or plastic, but a plastic substrate is preferred from various points. Examples of the plastic substrate include substrates made of acrylic resin, methacrylic resin, vinyl acetate resin, vinyl chloride resin, nitrocellulose, polyethylene resin, polypropylene resin, polycarbonate resin, polyimide resin, polysulfone resin, and the like.

Particularly preferred substrates include injection-molded polycarbonate resin substrates and methacrylic resin substrates which are excellent in mass productivity and have practical levels of birefringence, softening point and heat resistance. Recording on the optical recording medium obtained as described above is performed by irradiating a laser beam focused to about 1 μm onto a recording layer provided on both sides or one side of the substrate. The portion irradiated with the laser beam undergoes thermal deformation of the recording layer or substrate such as decomposition, evaporation, and dissolution due to absorption of laser energy.

Reproduction of recorded information is performed by reading the difference in reflectance between a portion where thermal deformation has occurred and a portion where thermal deformation has not occurred using a laser beam. As a light source,
Various lasers can be used, but a semiconductor laser is particularly preferable in terms of cost and size. As a semiconductor laser, a center wavelength of 830 nm or a center wavelength of 780
nm laser is preferred.

[0025]

The present invention will be described below in more detail with reference to examples, but the examples do not limit the present invention. Example 1 Compound (1) shown in Table 1: 1,3-bis [di (3-
[Methyl-1-azulenyl) methylium] benzenebishexafluorophosphate was synthesized as follows.

1.43 g of 1-methylazulene (10.0
Mmol) and 338 mg of isophthalaldehyde
(2.52 mmol) in 50 ml of glacial acetic acid at room temperature
Stir for 2 hours. The blue solution became a blue suspension.
After the reaction mixture was concentrated under reduced pressure, dichloromethane and water were added to the obtained residue. The organic layer was washed with a 5% aqueous sodium hydrogen carbonate solution and water, dried over magnesium sulfate, and concentrated under reduced pressure. The obtained residue is subjected to silica gel column chromatography (dichloromethane) and silica gel column chromatography (carbon tetrachloride).
Unreacted 1-methylazulene 265
mg (19% yield), 1,3-bis [di (3-methyl-
1-azulenyl) methyl] benzene 1.19 g (yield 7
1%, net 88%) as blue crystals and m-
[Di (3-methyl-1-azulenyl) methyl] benzaldehyde (219 mg, yield: 11%, net: 13%) was obtained as blue needles.

1,3-bis [di (3-methyl-1-az
The physical properties of [renyl) methyl] benzene are shown below. Mass spectrum (MS) (70 eV) m / z (rela
active intensity); 668 (M⁺+2
2), 667 (M⁺+1, 10), 666 (M ⁺, 1
7), 524 (14), 509 (6), 386 (6),
367 (6), 353 (6), 352 (5), 339
(7), 296 (16), 295 (62), 293
(7), 280 (12), 279 (35), 278
(8), 277 (5), 266 (10), 265 (3
0), 155 (7), 143 (7), 142 (67),
141 (100), 139 (17), 115 (17). IR (KBr) ν_max3028 (w), 2916
(W), 2856 (w), 1742 (m), 1596
(W), 1574 (s), 1522 (m), 1486
(M), 1436 (m), 1378 (m), 1362
(M), 1304 (m), 1238 (m), 1220
(W), 1168 (w), 1142 (w), 1090
(W), 1040 (w), 994 (w), 942
(M), 902 (w), 874 (m), 768 (w),
740 (s), 726 (s), 710 (m), 686
(M), 572 (m), 500 (w) cm^-1. Absorption spectrum (ES) (solvent CH_TwoCl_Two) Λ_max,
nm (log ε); 241 (4.75), 285
(5.09), 292 (5.07 sh), 298
(5.04 sh), 341 (4.08 sh), 35
7 (4.23), 374 (4.21), 580 (2.9)
2 sh), 604 (2.99 sh), 631 (3.
06), 662 (2.99 sh), 688 (2.97 sh)
 sh), 767 (2.51).

To a solution of 351 mg (0.527 mmol) of 1,3-bis [di (3-methyl-1-azulenyl) methyl] benzene obtained in the above manner in 50 ml of dichloromethane was added at room temperature 2,3-bis. Dichloro-5,6-
267 mg (1.18 mmol) of dicyano-p-benzoquinone were added. The blue suspension turned dark blue.
After stirring for 1 hour under the same conditions, 2.5 ml of 60% hexafluorophosphoric acid was added, and the mixture was further stirred for 15 minutes. Thereafter, 20 ml of water was added, and the resulting suspension was filtered off with suction. The organic layer was separated, washed with water, dried over magnesium sulfate, and concentrated under reduced pressure. The obtained residue was dissolved in 10 ml of dichloromethane, and 50 ml of ether was added. The precipitated crystals were filtered off with suction, washed with ether, and dried under reduced pressure to give 1,3-bis [di (3-methyl-1-azulenyl) methylium] benzenebishexafluorophosphate: compound (1) ) 503 mg (100% yield) as a black powder.

Melting point 300 ° C. or higher (dichloromethane / ether) MS (mass spectrum measurement by high-speed atom bombardment method) m / z 8
09 (M ⁺ -PF ₆ ), 664 (M ⁺ -2 PF ₆ ). Infrared absorption spectrum (IR) (KBr) ν _max ; 306
4 (w), 2976 (w), 2932 (w), 1700
(M), 1572 (m), 1542 (w), 1488
(S), 1444 (s), 1412 (s), 1348
(S), 1314 (s), 1288 (s), 1232
(M), 1196 (w), 1174 (m), 1072
(W), 1022 (m), 974 (w), 952
(W), 838 (s), 794 (w), 748 (m),
700 (w), 690 (w), 622 (w), 594
(W), 558 (m) cm ^-1 . ES (solvent CH ₃ CN) λ _max , nm (log ε);
234 (4.83), 267 (4.67 sh), 28
4 (4.64), 315 (4.49 sh), 367
(4.47), 399 (4.33 sh), 470
(3.99 sh), 496 (4.04), 645
(4.56 sh), 681 (4.67). ^{1 H NMR (400MHz, DMSO-} d 6, 80
℃) δ; 8.83 (d, 4H, J = 10.0, H 8),
8.24 (dd, 4H, J = 10.0, J = 10.0,
H ₆ ), 8.11 (dd, 4H, J = 10.0, J = 1
_{0.0, H 7), 7.97 (} d, 4H, J = 10.0,
H ₄ ), 7.92 (t, 1H, J = 8.0, H ₅ ),
7.91 (d, 4H, J = 1.0, H 2), 7.85
(Dd, 2H, J = 9.0, J = 1.8,
_{^{H 4,, 6,),}} 7.71 (dd, 4H, J = 10.0,
_{J = 10.0, H 5),} 7.49 (t, 1H, J = 1.
_{8, H 2), 2.67 (} d, 12H, J = 1.0,3-
Me). 200 mg of the compound (1) obtained as described above,
3-hydroxy-3-methyl-2-butanone (hereinafter referred to as H
(Abbreviated as MB) in 10 g, and filtered through a 0.22 μm filter to obtain a solution. At this time, there was no filtration residue on the filter.

5 ml of this solution was added to a 1.2 mm thick plate of 1.
After dripping onto an injection-molded polycarbonate resin substrate (5 inches in diameter) having a groove (groove) of 6 μm pitch, and applying the solution at a rotation speed of 1000 rpm by a spinner method, 60 ° C.
For 10 minutes. The maximum absorption wavelength of the coating film is 714n
m. FIG. 1 shows the visible spectrum absorption spectrum of the coating film. Storage stability test of coating film (70 ° C, 85%: 200
As a result, no crystallization or the like of the coating film was observed.

A reflective layer was formed by depositing gold on the coating film, and a hard coat treatment was performed on the reflective layer with an ultraviolet curable resin to prepare a sample. The prepared sample had a center wavelength of 78.
An EFM signal was recorded with a semiconductor laser beam of 0 nm, and the optimum recording sensitivity and the degree of modulation (I ₁₁ / I _top ) were determined. As a result, good initial recording characteristics were obtained. Furthermore, as a result of performing a light resistance test (xenon fade meter acceleration test: 60 hours) and a storage stability test (70 ° C., 85% RH: 500 hours), no deterioration in sensitivity and reproduction signal was observed as compared with the initial stage. Was extremely excellent as an optical recording medium.

Example 2 Compound (14) shown in Table-2: 1,4-bis [di (3
[Methyl-1-azulenyl) methylium] benzenebishexafluorophosphate was synthesized as follows.

1.44 g of 1-methylazulene (10.1
Mmol) and 342 mg of terephthalaldehyde
(2.55 mmol) in 50 ml of glacial acetic acid at room temperature
Stir for 2 hours. The blue solution became a blue suspension.
The precipitated crystals are filtered off with suction and washed with dichloromethane.
By drying under reduced pressure, 405 mg of 1,4-bis [di (3-methyl-1-azulenyl) methyl] benzene was obtained.
(Yield: 24%) as blue crystals (melting point: 300 ° C. or higher). The filtrate was concentrated under reduced pressure, and then diluted with benzene and water. The organic layer was separated, washed with a 5% aqueous sodium hydrogen carbonate solution and water, dried over magnesium sulfate, and concentrated under reduced pressure. The resulting residue was separated by silica gel column chromatography (dichloromethane) to obtain 469 mg of p- [di (3-methyl-1-azulenyl) methyl] benzaldehyde (yield: 25%) as blue needles.

The physical properties of 1,4-bis [di (3-methyl-1-azulenyl) methyl] benzene are shown below. MS (70 eV) m / z (relative inte
668 (M ^{++ 2,} 12), 667 (M
^{++ 1,} 43), 666 (M ⁺ , 78), 665 (1
4), 652 (7), 651 (13), 526 (1
0), 525 (5), 401 (10), 400 (3
0), 386 (14), 385 (14), 296
(5), 295 (18), 279 (8), 265
(6), 158 (7), 157 (5), 143 (8),
142 (69), 141 (100), 139 (11),
115 (18). IR (KBr) ν _max ; 3028 (w), 2916
(W), 1576 (s), 1522 (m), 1508
(M), 1438 (m), 1406 (w), 1364
(M), 1304 (w), 1266 (w), 1250
(W), 1238 (w), 1218 (w), 1188
(W), 1168 (w), 1142 (w), 1110
(W), 1056 (w), 1018 (w), 942
(M), 874 (m), 850 (w), 782 (m),
738 (s), 728 (s), 702 (w), 614
(W), 574 (w), 528 (w), 504 (w),
492 (w) cm ^-1 . ES (solvent CH ₂ Cl ₂ ) λ _max , nm (log
ε); 242 (4.80), 285 (5.17), 29
7 (5.11 sh), 344 (4.18 sh), 3
57 (4.30), 374 (4.27), 581 (2.
96 sh), 605 (3.03 sh), 631
(3.08), 659 (3.02 sh), 764
(2.54 sh).

168 mg (0.251 mmol) of 1,4-bis [di (3-methyl-1-azulenyl) methyl] benzene obtained as described above were added to dichloromethane 5
To the 0 ml solution at room temperature was added 131 mg (0.578 mmol) of 2,3-dichloro-5,6-dicyano-p-benzoquinone. The blue suspension turned dark blue. After stirring for 1 hour under the same conditions, 2.5 ml of 60% hexafluorophosphoric acid was added, and the mixture was further stirred for 15 minutes. Thereafter, 20 ml of water was added, and the resulting suspension was filtered off with suction. The organic layer was separated, washed with water, dried over magnesium sulfate, and concentrated under reduced pressure. The obtained residue was dissolved in 10 ml of dichloromethane, and 50 ml of ether was added. The precipitated crystals were collected by suction filtration, washed with ether, and dried under reduced pressure to give 1,4-bis [di (3-methyl-1-azulenyl) methylium] benzenebishexafluorophosphate: Compound (14) ) 240 mg (100% yield) as a black powder.

Melting point 300 ° C. or more (dichloromethane / ether) MS (mass spectrum measurement by high-speed atom bombardment method) m / z 6
64 (M ⁺ -2PF ₆ ). IR (KBr) ν _max ; 3065 (w), 2984
(W), 1700 (m), 1566 (m), 1488
(S), 1442 (s), 1412 (s), 1382
(S), 1346 (s), 1316 (s), 1288
(S), 1232 (m), 1174 (s), 1118
(W), 1070 (s), 1018 (m), 952
(W), 928 (w), 882 (m), 842 (s),
794 (m), 750 (m), 720 (w), 692
(W), 614 (w), 558 (m) cm ^-1 . ES (solvent CH ₃ CN) λ _max , nm (log ε);
230 (4.81), 259 (4.68 sh), 27
0 (4.64 sh), 284 (4.58 sh), 3
18 (4.39 sh), 347 (4.24), 377
(4.27 sh), 398 (4.31), 518
(4.18), 598 (4.14 sh), 681
(4.46). ^{1 H NMR (400MHz, DMSO-} d 6, 80
℃) δ; 8.87 (d, 4H, J = 9.8, H 8),
8.26 (dd, 4H, J = 9.8, J = 9.8,
_{H 6), 8.13 (dd,} 4H, J = 9.8, J = 9.
8, H ₇ ), 8.06 (d, 4H, J = 9.8,
_{H 4), 7.95 (d,} 4H, J = 1.0, H 2),
7.75 (dd, 4H, J = 9.8, J = 9.8,
_{H 5), 7.67 (s,} 4H, H 2,, 3,, 5,, 6,),
2.72 (d, 12H, J = 1.0, 3-Me). The compound (14) obtained as above was treated with 200 m
g and HMB (10 g) and filtered through a 0.22 μm filter to obtain a solution. At this time, there was no filtration residue on the filter.

5 ml of this solution was added to a 1.2 mm thick plate of 1.
The solution was dropped on a 6 μm pitch grooved injection molded polycarbonate resin substrate (5 inches in diameter), applied at a rotation speed of 800 rpm by a spinner method, and then dried at 60 ° C. for 10 minutes. The maximum absorption wavelength of the coating film was 715 nm, and the storage stability was good. A reflective layer was formed by depositing gold on the coating film, and a hard coat treatment was further performed on the reflective layer with an ultraviolet curable resin to prepare a sample. When the recording characteristics of the sample obtained in the same manner as in Example 1 were evaluated, good initial recording characteristics were obtained. Similarly,
As a result of light resistance and storage stability tests, no deterioration in sensitivity and reproduction signal was observed compared to the initial stage, and the optical recording medium was extremely excellent.

Example 3 200 mg of the compound (16) shown in Table 2 was added to HMB1
A sample was prepared in the same manner as in Example 2 except that the sample was dissolved in 0 g. The maximum absorption wavelength of the coating film was 720 nm, and the storage stability was good. When the recording characteristics of the sample obtained in the same manner as in Example 1 were evaluated, good initial recording characteristics were obtained. In the same manner, light resistance and storage stability tests were carried out. As a result, no deterioration in sensitivity and reproduction signal was observed compared to the initial stage, and the optical recording medium was extremely excellent.

[0039]

According to the present invention, it is possible to apply uniformly without invading the injection-molded plastic substrate (whitening, groove dripping, etc.), there is no crystallization at the time of application, and the obtained coating film (recording layer) Since an optical recording medium having excellent storage stability and high reflectance and high sensitivity can be obtained, it is extremely useful industrially.

[Brief description of the drawings]

FIG. 1 is a view showing the spectrum of the visible part of the compound of the present invention obtained in Example 1.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References Tetrahedron Letters, Vol. 33, No. 26 (23 June 1992) p. 3773-3774 (58) Field surveyed (Int. Cl. ⁷ , DB name) CA (STN) CAOLD (STN) REGISTRY (STN)

Claims (1)

(57) [Claims] An optical recording medium having a recording layer obtained by applying a solution obtained by dissolving a laser-absorbing dye in an organic solvent onto a substrate, and then drying the resultant. An optical recording medium characterized by using an azulene compound represented by the formula: Embedded image Wherein R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ and R ⁸
Each independently represents a hydrogen atom or an alkyl group, and X ^- represents an anion. )