JPH09194748A - Optical recording medium and information recording method - Google Patents

Abstract

(57) Abstract: An optical recording medium capable of recording and reproducing with a laser beam having a relatively short wavelength is obtained. An optical recording medium comprising an organic dye layer containing a benzopyran compound represented by the following general formula [I] on a substrate. Embedded image

Description

Detailed Description of the Invention

[0001]

The present invention relates to an optical recording medium recordable by laser light and an information recording method using the same.

[0002]

2. Description of the Related Art In recent years, attention has been paid to shortening the oscillation wavelength of laser light for high-density recording.
There is a demand for an optical recording medium capable of recording and reproducing with a laser beam having a shorter wavelength. Optical recording media proposed in such a situation include a magneto-optical recording medium, a phase change recording medium, a chalcogen oxide-based optical recording medium, an organic dye-based optical recording medium, and the like. Among these, the organic dye-based optical recording medium is considered to be superior in that it is inexpensive and easy to process.

[0003] By the way, as an organic dye-based optical recording medium, a type in which a highly reflective metal layer is laminated on a thin organic dye layer as a recordable compact disc is widely known. The configuration has poor recording sensitivity and is disadvantageous for recording at a high linear velocity. In addition, since the substrate is deformed in addition to the dye at the time of recording, the bit length reproduction method has a problem that the bit length varies greatly and the jitter increases.

On the other hand, a great deal of research has been conducted on a recording method using a single layer of an organic dye, including a method of recording / reproducing light incident on a film surface, and a part thereof has been put into practical use as an optical recording medium for 780 nm. I have. However, for short wavelength applications, see JP-A-4-74690 and JP-A-4-23.
Although various proposals have been made, such as JP-A No. 8036 and JP-A-5-38878, the light resistance, environmental resistance, and the like are completely inadequate, and any problems inherent in short-wavelength applications have been solved. There is no present.

[0005]

Conventionally, there has been a problem that the formation of a rim caused by recording is disadvantageous for an organic dye-based optical recording medium for short wavelength applications, that is, for high density recording by short bit recording. . Also, it was difficult to obtain sufficient recording density and recording characteristics in high linear velocity recording of 10 m / s or more.

[0006]

In order to realize high-density recording, the present inventor has formed a fine minute recording portion having no rim, and has a wavelength 620 having sufficient characteristics even at high linear velocity recording. As a result of intensive studies on a medium and conditions suitable for recording at a short wavelength of up to 690 nm, the present invention has been reached. The gist of the present invention is an optical recording medium having an organic dye layer on a substrate for recording / reproducing with a laser beam having a wavelength of 620 to 690 nm, wherein the organic dye layer is a benzopyran represented by the following general formula [I]. The present invention resides in an optical recording medium for short wavelength recording, which is characterized by a system compound.

[0007]

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(In the formula, R ¹ and R ² represent an optionally substituted alkyl group, a cycloalkyl group or an aryl group, and R ¹ and R ² together with a nitrogen atom form a heterocycle. X represents a hydrogen atom, an alkyl group, an alkoxy group, a halogen atom, a cyano group, a nitro group or an optionally substituted carbamoyl group, a sulfamoyl group or a carboalkoxy group, and Y represents an oxygen atom, a sulfur atom, Represents NR, R represents a hydrogen atom, an optionally substituted hydrocarbon group, an acyl group or a sulfonyl group, and the ring A represents an optionally substituted aromatic carbocycle or aromatic heterocycle.)

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below.
The optical recording medium of the present invention has a configuration in which an organic dye layer is provided on a substrate, but depending on the purpose, a thin ceramic layer is formed on the organic dye layer, or an ultraviolet curable resin is laminated. Is also good. Alternatively, two media having an organic dye layer provided on a substrate may be bonded to each other with a so-called air sandwich system in which the organic dye layers face each other and are bonded via a spacer.

As the substrate, a known transparent substrate having a small birefringence, such as a polycarbonate substrate, an amorphous polyolefin substrate, or a glass substrate, is preferably used. The organic dye layer is usually formed by dissolving the organic dye in a solvent on a substrate and drying it, or by vacuum-depositing the organic dye on the substrate. As the solvent in the case of the coating method, for example,
In the case of a polycarbonate substrate, those which do not attack the polycarbonate substrate such as ethanol, 3-hydroxy-3-methyl-2-butanone, diacetone alcohol, and fluorinated alcohol are preferably used. In the case of a polyolefin substrate, chloroform, methyl ethyl ketone is used. And the like are preferably used.

The organic dye layer has a spectral absorption maximum of 510
nm to 730 nm. 51
If there is an absorption maximum in a wavelength region shorter than 0 nm, sufficient sensitivity cannot be obtained in the layer constitution of the present invention. Or,
A good reproduction signal cannot be obtained. The same applies to an organic dye layer having an absorption maximum on the longer wavelength side than 730 nm.

The thickness of the organic dye layer is 20 to 100 n.
m is preferably in the range. The thickness of the organic dye layer is 2
When the thickness is less than 0 nm, the coating film is formed only in the grooves, and it becomes difficult to record between the grooves. On the other hand, if it exceeds 100 nm, the rim becomes thicker, and the asymmetry of the recording portion in the scanning direction of the laser beam is emphasized. In the present invention, the benzopyran dye represented by the general formula [I] is used as the organic dye.

In the above general formula [I], R ¹ and R ² are methyl, ethyl, n-propyl, isopropyl, n-butyl, tert-butyl, sec.
-Butyl group, n-pentyl group, n-hexyl group, n-heptyl group, n-octyl group, n-decyl group, n-dodecyl group, n-octadecyl group and the like, preferably an alkyl group having 1 to 20 carbon atoms. Is an alkyl group having 1 to 10 carbon atoms, more preferably an alkyl group having 1 to 6 carbon atoms; an aryl group having 6 to 12 carbon atoms such as phenyl group, tolyl group, xylyl group and naphthyl group; vinyl group, 1-propenyl Groups, allyl groups, isopropenyl groups, 2-butenyl groups, 1,3-butadienyl groups, 2-pentenyl groups and other alkenyl groups having 2 to 10 carbon atoms; benzyl groups, phenethyl groups and other arylalkyl groups; or cyclopropyl Examples thereof include cycloalkyl groups having 3 to 10 carbon atoms such as groups, cyclobutyl groups, cyclopentyl groups, cyclohexyl groups, cycloheptyl groups and cyclooctyl groups. R ¹ and R ² may be cyclized to form a heterocycle such as a piperidine ring or a morpholine ring. X is a hydrogen atom; an alkyl group having 1 to 20 carbon atoms such as a methyl group, an ethyl group, an n-propyl group, an n-butyl group; a methoxy group,
C1-C20 alkoxy groups such as ethoxy group, n-propoxy group, n-butoxy group; halogen atoms such as chlorine atom, bromine atom, iodine atom, fluorine atom; cyano group; nitro group; carbamoyl group, methylcarbamoyl Group, optionally substituted carbamoyl group such as ethylcarbamoyl group; methoxycarbonyl group, ethoxycarbonyl group,
an optionally substituted carboalkoxy group such as an n-propoxycarbonyl group; an optionally substituted sulfamoyl group such as a sulfamoyl group, a methylsulfamoyl group, an ethylsulfamoyl group and an n-propylsulfamoyl group, Can be mentioned. Y is an oxygen atom, sulfur atom, imino group, methylamino group, ethylamino group, n-butylamino group, phenylamino group, benzylamino group, acetylamino group, propionylamino group, benzoylamino group, benzylcarbonylamino group, Examples thereof include a methylsulfonylamino group and an ethylsulfonylamino group.

Examples of ring A include aromatic carbocycles such as phenyl ring and naphthyl ring, and aromatic heterocycles such as thiophene ring and benzothiophene ring. As the substituent which may be substituted with ring A, Methoxy group, ethoxy group, n-propoxy group, isopropoxy group, n-butoxy group, te
C1-C10 alkoxy groups such as rt-butoxy group, sec-butoxy group, n-pentyloxy group, n-hexyloxy group, n-heptyloxy group, n-octyloxy group, n-decyloxy group; methoxy Carbon number of 2 such as methoxy group, ethoxymethoxy group, propoxymethoxy group, methoxyethoxy group, ethoxyethoxy group, propoxyethoxy group, methoxypropoxy group, ethoxypropoxy group, methoxybutoxy group, ethoxybutoxy group
12 alkoxyalkoxy groups; 3 carbon atoms such as methoxymethoxymethoxy group, methoxymethoxyethoxy group, methoxyethoxymethoxy group, methoxyethoxyethoxy group, ethoxymethoxymethoxy group, ethoxymethoxyethoxy group, ethoxyethoxymethoxy group, ethoxyethoxyethoxy group, etc. To 15 alkoxyalkoxyalkoxy group; allyloxy group; aryl group having 6 to 12 carbon atoms such as phenyl group, tolyl group, xylyl group and naphthyl group; phenoxy group, tolyloxy group, xylyloxy group and naphthyloxy group having 6 carbon atoms 12 aryloxy groups;
Cyano group; nitro group; hydroxy group; tetrahydrofuryl group; methylsulfonylamino group, ethylsulfonylamino group, n-propylsulfonylamino group, isopropylsulfonylamino group, n-butylsulfonylamino group, tert-butylsulfonylamino group, sec -Butylsulfonylamino group, n-pentylsulfonylamino group, n-hexylsulfonylamino group and the like having 1 to 1 carbon atoms
6 alkylsulfonylamino group; halogen atom such as fluorine atom, chlorine atom, bromine atom; methoxycarbonyl group, ethoxycarbonyl group, n-propoxycarbonyl group, isopropoxycarbonyl group, n-butoxycarbonyl group, tert-butoxycarbonyl group , Sec-butoxycarbonyl group, n-pentyloxycarbonyl group, n-hexyloxycarbonyl group and the like having 2 to 7 carbon atoms
Alkoxycarbonyl group; methylcarbonyloxy group, ethylcarbonyloxy group, n-propylcarbonyloxy group, isopropylcarbonyloxy group, n-butylcarbonyloxy group, tert-butylcarbonyloxy group, sec-butylcarbonyloxy group, n- An alkylcarbonyloxy group having 2 to 7 carbon atoms such as a pentylcarbonyloxy group and an n-hexylcarbonyloxy group; a methoxycarbonyloxy group, an ethoxycarbonyloxy group, an n-propoxycarbonyloxy group, an isopropoxycarbonyloxy group, and an n-butoxy group Carbonyloxy group, tert-butoxycarbonyloxy group, s
Examples thereof include an alkoxycarbonyloxy group having 2 to 7 carbon atoms such as an ec-butoxycarbonyloxy group, an n-pentyloxycarbonyloxy group, and an n-hexyloxycarbonyloxy group. Among these, preferred benzopyran compounds in the present invention include the following general formula [II]
The compound represented by these is mentioned.

[0015]

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(Wherein R ³ and R ⁴ represent a C _1-12 linear or branched alkyl group, R ⁵ represents an oxygen atom, a sulfur atom, an imino group or NR ⁸ and R ⁸ represents A C _1-12 linear or branched alkyl group or acyl group is shown.
⁶ , R ⁷ represents a hydrogen atom, an alkyl group, an alkoxy group, a halogen atom, a cyano group, a nitro group or an optionally substituted carbamoyl group, a sulfamoyl group or a carboalkoxy group. ) Particularly preferable benzopyran compounds include compounds represented by the following general formula [III].

[0017]

[Chemical 6]

(Where R⁹, R^TenIs C_1-6No straight chain
Represents a branched lower alkyl group, R ¹¹Is an oxygen atom, sulfur
Indicates a yellow atom or imino group. ) Specific examples of benzopyran compounds used in the present invention
For example, the following compounds may be mentioned.

[0019]

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[0020]

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[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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These dyes may be used alone or 2
You may mix and use more than one kind. To perform recording and reproduction using the optical recording medium of the present invention, the wavelengths of 620 to 6 are applied from the substrate side.
90 nm laser light is made incident. The incident laser light is absorbed by the organic dye layer to generate heat, and when the temperature reaches a temperature exceeding the main weight loss start temperature, the laser light starts to be decomposed into fragments of low molecular weight, thereby forming a concave portion. Since a slight amount or little of the dye remains in the concave portion, the reflectance decreases when the reproduction light is irradiated, and the concave portion is detected as a recording portion.

The shape of the recording portion greatly differs depending on the dye used, and the rim becomes thinner as the film thickness is made thinner, but the asymmetry of the recording portion is not always improved. Among them, particularly in an optical recording medium having an organic dye layer composed of a benzopyran dye represented by the above general formulas [I], [II] and [III], a rim is hardly formed and high linear velocity recording is performed. Also in the above, it is preferable because it shows a good jitter characteristic.

[0028]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, but it should not be construed that the present invention is limited to the following Examples without departing from the scope of the invention. Example 1 As a transparent substrate, a recording groove having a diameter of 120 mm provided with a periodically meandering tracking groove for a recordable compact disc,
A polycarbonate substrate having a thickness of 1.2 mm was used. The organic dye layer is formed by dissolving the benzopyran-based compound represented by the structural formula (A-11) in tetrafluoropropanol at a concentration of 2.5% by weight, filtering, and then forming a film on the substrate by spin coating. did. After applying the dye, drying was performed for 30 minutes in an oven at 100 ° C. in order to completely evaporate the solvent in the dye layer.

Then, as a light reflecting layer on the light absorbing layer,
Gold having an average thickness of 100 nm was formed by DC magnetron sputtering. Further, an ultraviolet curing agent SD-318 (manufactured by Dainippon Ink and Chemicals, Inc.) was applied on the light reflecting layer by a spin coating method to a thickness of 4 μm, and was irradiated with ultraviolet rays by an ultraviolet irradiation device to be cured, A protective layer was formed. 635 nm for the obtained recordable compact disc
When the FEM signal was recorded and the initial characteristics were evaluated with the semiconductor laser of No. 2, the bit length jitter was good, and a good rim-shaped recording portion was obtained. Temperature 80 ℃, Humidity 90%
When the change in the block error rate was measured after the high temperature and high humidity test for 500 hours under the above condition, a slight increase in the error was observed.

The drive used in this evaluation is basically a drive that can be evaluated based on the current compact disk standard, except that the optical head is changed to a 635 nm laser. The EFM signal modulation method and the like are the same as those of the current compact disc, and the block error rate was evaluated according to this modulation method. Further, in the present compact disc, by increasing the clock frequency and the track pitch, good characteristics were obtained even with a half pitch (0.8 μm) and half mark length of the current compact disc.

Example 2 Example 1 was repeated except that the coating solution was prepared by dissolving the benzopyran compound represented by the structural formula (A-12) in octafluoropentanol at a concentration of 2.4% by weight. Similarly, a recordable compact disc was produced. When the obtained disc was tested in the same manner as in Example 1, the EFM signal recording and the initial characteristic evaluation (bit length jitter) were good with a semiconductor laser of 635 nm, and a good rim-shaped recording portion was obtained. It was Further, when the test was conducted in the same manner as in Example 1, a slight increase in error was observed.

Example 3 Example 1 was repeated except that the coating solution was prepared by dissolving the benzopyran compound represented by the structural formula (B-5) in octafluoropentanol at a concentration of 2.6% by weight. Similarly, a recordable compact disc was produced. When the obtained disk was tested in the same manner as in Example 1, the EFM signal recording and the initial characteristic evaluation (bit length jitter) were good with a semiconductor laser of 635 nm.
A recording portion having a good rim shape was obtained. Further, when the test was conducted in the same manner as in Example 1, a slight increase in error was observed.

Example 4 A coating solution was prepared by dissolving the benzopyran compound represented by the structural formula (B-10) in 3-hydroxy-3-methyl-2-butanone at a concentration of 1.2% by weight. A recordable compact disc was manufactured in the same manner as in Example 1 except for the above. When the obtained disc was tested in the same manner as in Example 1, the EFM signal recording and the initial characteristic evaluation (bit length jitter) were good with a semiconductor laser of 635 nm, and a good rim-shaped recording portion was obtained. It was Further, when the test was conducted in the same manner as in Example 1, a slight increase in error was observed.

Example 5 The same as Example 1 except that the benzopyran compound represented by the structural formula (C-10) was dissolved in tetrafluoropropanol at a concentration of 2.4% by weight to prepare a coating solution. Then, a recordable compact disc was produced. When the obtained disc was tested in the same manner as in Example 1, the EFM signal recording and the initial characteristic evaluation (bit length jitter) were good with a semiconductor laser of 635 nm, and a good rim-shaped recording portion was obtained. It was Further, when the test was conducted in the same manner as in Example 1, a slight increase in error was observed.

Example 6 Same as Example 1 except that the coating solution was prepared by dissolving the benzopyran compound represented by the structural formula (D-3) in diacetone alcohol at a concentration of 2.2% by weight. Then, a recordable compact disc was produced. When the obtained disk was tested in the same manner as in Example 1, 6
The EFM signal recording and initial characteristic evaluation (bit length jitter) were good with a semiconductor laser of 35 nm, and a good rim-shaped recording portion was obtained. Further, when the test was conducted in the same manner as in Example 1, a slight increase in error was observed.

[0036]

The optical recording medium of the present invention has a good minute recording portion with almost no rim, little bit length jitter, and sufficient recording sensitivity and recording characteristics as an optical recording medium for high linear velocity short wavelength recording. Since it can be achieved, it is very useful and can be suitably used for so-called SD-R and DVD-R standards.

Claims (5)

[Claims] 1. An optical recording medium having an organic dye layer on a substrate, wherein the organic dye layer contains a benzopyran-based compound represented by the following general formula [I] and has a wavelength of 620 to 690 nm. An optical recording medium for short wavelength recording for recording / reproducing with laser light. Embedded image (In the formula, R ¹ and R ² represent an optionally substituted alkyl group, a cycloalkyl group or an aryl group, and R ¹ and R ² may combine with a nitrogen atom to form a heterocycle. X represents a hydrogen atom, an alkyl group, an alkoxy group, a halogen atom, a cyano group, a nitro group or an optionally substituted carbamoyl group, a sulfamoyl group or a carboalkoxy group, and Y represents an oxygen atom, a sulfur atom or N.
R represents a hydrogen atom, an optionally substituted hydrocarbon group, an acyl group or a sulfonyl group. Ring A represents an optionally substituted aromatic carbocycle or aromatic heterocycle. ) 2. The optical recording medium according to claim 1, wherein the benzopyran compound is represented by the following general formula [II]:
An optical recording medium, which is a compound represented by: Embedded image (In the formula, R ³ and R ^{4 each} represent a C _1-12 linear or branched alkyl group, R ⁵ represents an oxygen atom, a sulfur atom, an imino group or NR ⁸ , and R ⁸ represents C _{1- 12 represents} a linear or branched alkyl group or an acyl group, wherein R ⁶ and R ⁷ represent a hydrogen atom, an alkyl group, an alkoxy group, a halogen atom, a cyano group, a nitro group or an optionally substituted carbamoyl group, Indicates a sulfamoyl group or a carboalkoxy group.) 3. The optical recording medium according to claim 1.
In the body, the benzopyran-based compound is represented by the following general formula [III
 ] Optically characterized by being a compound represented by
recoding media. Embedded image(Where R⁹, R^TenIs C_1-6Linear or branched low
Represents a primary alkyl group, R ¹¹Is an oxygen atom, a sulfur atom or
Indicates an imino group. ) 4. The optical recording medium according to claim 1, wherein a metal reflective layer and a protective layer are provided on the organic dye. 5. An information recording method, wherein a recording portion is formed by irradiating the optical recording medium according to claim 1 with a laser beam having a wavelength of 620 to 690 nm.