JPH11277904A - Optical recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance water resistance and preservative stability by allowing a recording layer to contain a nitroso-compound and aluminum salt. SOLUTION: A postscript type disc is manufactured, which contains cyanin coloring matter, a nitroso-compound and aluminum salt in a recording layer. Polycarbonate resin is injection molded to manufacture a disc-shaped transparent substrate having preformat patterns formed thereon and a central hole in its center. Preformat patterns are provided with a guide grooves 5 to allow a recording and reproduction laser beam to follow, recording tracks 8 defined by the guide grooves 5, and prepits 6 to display a section address or a standard clock. The guide grooves 5 are formed in a concentric spiral or in a concentric shape. Also, the guide grooves 5 can be detected from wobble grooves. Furthermore, the guide grooves 5 and prepits 6 can be formed in different depths respectively.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical information recording medium having an organic dye-based recording layer, and more particularly, to an optical information recording medium having excellent light resistance and storage stability and having a relatively high reflectance to reproduction light. The present invention relates to a write-once optical information recording medium.

[0002]

2. Description of the Related Art In recent years, with the development of information technology, an optical recording medium which is a small and large-capacity recording medium has been used. Such an optical recording medium is a CD (compact disk).
, A write-once recording medium such as a CD-R (compact disk-recordable), which can be written only once, and a rewritable recording medium represented by a magneto-optical disk. Among these, a write-once recording medium using an organic dye for a recording layer is known.

Japanese Patent Laid-Open No. 2-168446 discloses a writable optical information recording medium having a high reflectance and capable of obtaining an output signal conforming to the CD format for information reproduction, ie, a write-once CD ( CD-R). This write-once CD has a recording layer containing an organic dye on a substrate surface on which a preformat pattern is formed,
It has a structure in which a reflective layer and a protective layer are sequentially laminated, and when recording information, irradiates the recording layer with a laser beam and alters the organic dye constituting the recording layer by the thermal energy of the laser beam. In addition to changing the optical characteristics, recording is performed by deforming a part of the transparent substrate which is the base of the recording portion of the recording layer.

[0004]

As an organic dye used in the recording layer of the write-once optical recording medium as described above, a cyanine dye is known (Japanese Patent Application Laid-Open No. 58-11279).
0, JP-A-59-24692, JP-A-5-67349
etc). However, the cyanine-based dye layer is generally liable to be deteriorated by light such as sunlight or a reproduction laser. Causes of this deterioration include autoxidation and cleavage of the dye molecules by ultraviolet rays, but mainly in the organic dye layer, oxygen is excited to a singlet electronic state, and this singlet oxygen is unsaturated in the dye molecules. It is thought to be due to reacting with the group. An optical recording medium in which a singlet oxygen quencher is added to a recording layer in order to improve the light fastness of an organic dye constituting the recording layer has been proposed in JP-A-59-55795.
Not enough for light fastness.

The applicants have disclosed in Japanese Patent Application Laid-Open No. 5-67349 that the light resistance and the storage stability of an optical recording medium are improved by adding an aminium salt as a deterioration inhibitor to an organic dye material of the optical recording medium. Was disclosed.
An optical recording medium using an aminium salt compound as a cyanine dye deterioration inhibitor is also disclosed in Japanese Patent No. 25551474. However, since the aminium salt has an absorption band at a wavelength of 770 to 790 nm of the reproduction laser light, the reflectance is reduced by partially absorbing the reproduction light. For example, since a CD-R requires a reflectance of 65% for reproduction light, such a decrease in reflectance is not desirable.

Further, an optical recording medium using a nitroso compound as a deterioration inhibitor of an organic dye of the optical recording medium is disclosed in, for example,
It is disclosed in Japanese Patent Application No. 2-300287.

An object of the present invention is to solve the above-mentioned problems of the prior art, and to provide an optical information recording medium having an organic dye recording layer having excellent light resistance and storage stability and having a high reflectance. It is in.

[0008]

According to the present invention, in an optical recording medium having a recording layer containing a cyanine organic dye on a substrate, the recording layer contains a nitroso compound and an aminium salt. An optical recording medium is provided.

In the optical recording medium of the present invention, a nitroso compound and an aminium salt are used in combination as additives for preventing deterioration of the cyanine organic dye used in the recording layer.
By using a nitroso compound and an aminium salt in combination, it is possible to prevent the deterioration of the cyanine-based organic dye and to maintain a favorable reflectance required for reproducing an optical recording medium. According to the knowledge of the present inventors, the above recording layer is composed of 40 to 97% by weight of a cyanine dye and 3 to 60% by weight of a mixture of a nitroso compound and an aminium salt, wherein the nitroso compound and the aminium salt are mixed. The salt is a nitroso compound / aminium salt = 20 / 80-80 / 20
It has been found that mixing at a weight ratio of is more effective. In particular, the weight mixing ratio of the nitroso compound and the aminium salt is set such that the nitroso compound / aminium salt = 50 / 50-
By adjusting the ratio to 25/75, deterioration of the cyanine dye can be prevented as compared with the case where the aminium salt or the nitroso compound is used alone, and the predetermined reflectance required for reproduction of the write-once optical recording medium can be maintained. I understood.

As the nitroso compound for use in the optical recording medium of the present invention, a nitroso compound represented by the following general formula (1) is preferable because it exhibits a good function of preventing deterioration of cyanine dyes.

[0011]

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Wherein R may be the same or different;
Shows a hydrocarbon group or hydrogen. When R is a hydrocarbon, for example, it may be an alkyl group such as a methyl group or an aromatic hydrocarbon group such as an aryl group.

As the aminium salt used in the optical recording medium of the present invention, a compound represented by the following general formula (2) is preferable.

[0014]

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Wherein R may be the same or different;
Shows a hydrocarbon group or hydrogen. When R is a hydrocarbon, it may be, for example, an alkyl group such as a methyl group, an ethyl group, or a propyl group, or an aromatic hydrocarbon group such as an aryl group. Where:
X ⁻ represents a counter ion, represents an organic anion, a halogen ion, a metal complex ion or a halide ion;
For ^{example, Cl -, I -, ClO} 4 - may in like or anionic dyes. n represents an ionic valence and is 1 or 2.

As the organic dye constituting the recording layer of the optical recording medium of the present invention, a cyanine dye is used. Dyes other than cyanine dyes, for example, polymethine dyes such as squarylium dyes and azulhenium dyes, macrocyclic azaannulene dyes such as phthalocyanine dyes, and dithiol dyes may be added to the cyanine dye. The recording layer may contain a deterioration inhibitor such as a singlet oxygen quencher, an ultraviolet absorber, an infrared absorber, an antioxidant, and a reducing agent.

The ratio of the cyanine dye constituting the recording layer to the deterioration inhibitor is 5 to 60 parts by weight of the deterioration inhibitor and 100 parts by weight of the organic dye constituting the recording layer of the optical recording medium. It is preferable to use 10 to 30 parts by weight of the inhibitor. Further, a resin such as an acrylic resin, a polycarbonate resin, a polyester resin, or polyvinyl alcohol may be added to the recording layer as needed.

In order to form the recording layer on the substrate, a dry process such as vacuum evaporation or sputtering may be used.
The organic material constituting the recording film may be mixed with an alcohol-based solvent such as methanol, ethanol, or isopropyl alcohol, a cellsolve-based solvent such as methylcellosolve or ethylcellosolve, or a ketone-based solvent such as acetone or methylethylketone.
It is preferable to use a wet process of dissolving 0% and forming a film by a spin coating method. The thickness of the dye layer is 3
It is preferably from 0.00 to 3000 A (angstrom), and more preferably from 500 to 2000 A (angstrom).

The optical recording medium of the present invention is a write-once recording medium,
In particular, it is preferable to use it as a write-once CD (CD-R). For this reason, a structure in which a recording layer, a reflective layer, and a protective layer are stacked on a substrate is generally used.

As the substrate, acrylic, polycarbonate, polymethyl methacrylate, polymethyl pentene,
A transparent resin substrate material such as polyolefin or epoxy can be used, and it is preferable that such a material is injection-molded using a stamper or the like in which a preformat signal is formed in the form of a pit. Alternatively, a transparent ceramic plate such as glass having a replica layer of a photocurable resin formed on one surface can be used as the substrate.

The reflective layer can be recorded on the recording layer by a dry process such as sputtering using an arbitrary reflective substance such as gold, aluminum, silver, copper, or an alloy containing these materials as a main component. .

The protective layer is made of SiO ₂ , SiN, AlN, A
An organic material such as an inorganic material such as l ₂ O ₃ , an ultraviolet curable resin, a thermosetting resin, a two-component mixed type curable resin, and a room temperature curable resin can be formed on the reflective layer by, for example, spin coating.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited to these embodiments.

Example 1 In this example, a write-once disc containing a cyanine dye, a nitroso compound and an aminium salt in the recording layer is manufactured. Polycarbonate resin was injection molded to produce a transparent substrate on a disk having a preformat pattern formed and having a center hole in the center. FIG. 2 shows an outline of the planar structure of the obtained substrate 1. In the preformat pattern, a guide groove 5 for causing a recording / reproducing laser beam to follow, a recording track 8 defined by the guide groove 5, a prepit 6 for displaying a sector address and a reference clock are formed. The guide groove 5 is formed in a concentric spiral or concentric shape with the center hole 7. Further, the guide groove 5 may be a wobble groove, whereby the type of information can be detected from the wobble groove. Further, the guide groove 5 and the pre-pit 6 can be formed at different depths. In this embodiment, a wobble groove is employed.

A recording layer was formed on the polycarbonate substrate 1 manufactured as described above as follows. 6 parts by weight of a cyanine dye represented by the following structural formula (6), 10 parts by weight of a cyanine dye shown by a structural formula (7), and structural formula (8)
1 part by weight of a nitroso compound represented by the following formula and 3 parts by weight of an aminium salt represented by the structural formula (9) were combined with 1,2-dichloroethane 190
It was dissolved in a mixed solvent of parts by weight and 190 parts by weight of ethyl cellosolve. After the obtained solution was filtered through a 0.5 μm filter, the filtrate was applied on the surface of the polycarbonate substrate 1 on which a preformat pattern was formed with a thickness of 100 nm to form a dye layer (recording layer) (dye disk A).

After drying the dye layer, an Au reflection layer was formed to a thickness of 140 nm on the dye layer by using a sputtering apparatus. Finally, spin-coat the ultraviolet curable resin to a thickness of 3
The protective layer was formed by coating to a thickness of μm.

The optical disk (optical disk A) thus obtained is, as shown in FIG.
There is a structure in which a recording layer 2, an Au reflection layer 3, and an ultraviolet curable resin protective layer 4 are sequentially laminated thereon.

[0028]

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[0029]

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[0030]

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[0031]

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Example 2 A polycarbonate substrate 1 produced in the same manner as in Example 1
6 parts by weight of the cyanine dye represented by the structural formula (6), 9 parts by weight of the cyanine dye represented by the structural formula (7), 2 parts by weight of the nitroso compound represented by the structural formula (8), and the structural formula (9) 2 parts by weight of the aminium salt shown in
It was dissolved in a mixed solvent of 90 parts by weight and 190 parts by weight of ethyl cellosolve. After the obtained solution was filtered through a 0.5 μm filter, the filtrate was applied on the surface of the polycarbonate substrate 1 on which the preformat pattern was formed with a thickness of 100 nm to form a dye layer (recording layer) (dye disk). B).

After drying the dye layer, an Au reflective layer was formed on the dye layer to a thickness of 140 nm using a sputtering apparatus. Finally, spin-coat the ultraviolet curable resin to a thickness of 3
A protective layer was formed by coating to a thickness of μm (optical disc B).

Example 3 6 parts by weight of a cyanine dye represented by the structural formula (6) and 10 parts by weight of a cyanine dye represented by the structural formula (7) were formed on a polycarbonate substrate 1 produced in the same manner as in Example 1. 3 parts by weight of the nitroso compound represented by the structural formula (8) and the structural formula (9)
Was dissolved in a mixed solvent of 190 parts by weight of 1,2-dichloroethane and 190 parts by weight of ethylcellosolve. After the obtained solution was filtered through a 0.5 μm filter, the filtrate was applied on the surface of the polycarbonate substrate 1 on which the preformat pattern was formed with a thickness of 100 nm to form a dye layer (recording layer) (dye disk). C).

After drying the dye layer, an Au reflection layer was formed on the dye layer to a thickness of 140 nm using a sputtering apparatus. Finally, spin-coat the ultraviolet curable resin to a thickness of 3
A protective layer was formed by coating the particles on a thickness of μm (optical disk C).

Comparative Example 1 6 parts by weight of a cyanine dye represented by the structural formula (6) and 10 parts by weight of a cyanine dye represented by the structural formula (7) were formed on a polycarbonate substrate 1 produced in the same manner as in Example 1. 4 parts by weight of the aminium salt represented by the structural formula (8) were dissolved in a mixed solvent of 190 parts by weight of 1,2-dichloroethane and 190 parts by weight of ethylcellosolve. After the obtained solution was filtered through a 0.5 μm filter, the filtrate was applied on the surface of the polycarbonate substrate 1 on which the preformat pattern was formed with a thickness of 100 nm to form a dye layer (recording layer) (dye disk). D).

After drying the dye layer, an Au reflection layer was formed on the dye layer to a thickness of 140 nm using a sputtering apparatus. Finally, spin-coat the ultraviolet curable resin to a thickness of 3
A protective layer was formed by coating the particles with a thickness of μm (optical disk D).

Comparative Example 2 6 parts by weight of a cyanine dye represented by the structural formula (6) and 10 parts by weight of a cyanine dye represented by the structural formula (7) were formed on a polycarbonate substrate 1 prepared in the same manner as in Example 1. 4 parts by weight of the nitroso compound represented by the structural formula (8) was dissolved in a mixed solvent of 190 parts by weight of 1,2-dichloroethane and 190 parts by weight of ethylcellosolve. After the obtained solution was filtered through a 0.5 μm filter, the filtrate was coated on the surface of the polycarbonate substrate 1 on which the preformat pattern was formed to a thickness of 1 μm.
A 00 nm dye layer (recording layer) was formed (dye disk E).

After drying the dye layer, an Au reflection layer was formed on the dye layer to a thickness of 140 nm using a sputtering apparatus. Finally, spin-coat the ultraviolet curable resin to a thickness of 3
A protective layer was formed by coating the particles with a thickness of μm (optical disk E).

The optical disks A to E obtained in Examples 1 to 3 and Comparative Examples 1 and 2 were rotated at a linear velocity of 4.8 m / sec, and EF was performed using a semiconductor laser having a wavelength of 780 nm.
The M signal was recorded at a laser power (output value) of 13 mW. CD-ROM
It was measured by an inspection machine. The reflectivities of the optical disks A to E obtained in Examples 1-3 and Comparative Examples 1 and 2 were measured, and the content (% by weight) of the nitroso compound and the aminium salt in the deterioration inhibitor mixture in the recording layer was measured. FIG. 3 shows the relationship of the reflectivity of the disk to ()). The reflectivity of the disc decreases as the content of the aminium salt increases, and the optical discs of Examples 1 to 3 and Comparative Example 1 according to the present invention in which the content of the aminium salt is 75% or less have a high reflectivity of 65% or more. Show.

Dye discs A to A coated with only the dyes obtained in Examples 1 to 3 and Comparative Examples 1 and 2
E, temperature 30 degrees, relative humidity 80%, illuminance 9000Lx
(Xenon lamp) for 500 hours, and an environment resistance test was performed. The absorbances of the dye disks A to E obtained in Examples 1-3 and Comparative Examples 1 and 2 were measured before and after the environmental test. The absorbance of each disk was determined by irradiating white light to the recording track area of the disk, and the maximum absorption wavelength of the cyanine dye used in Examples was 680 n.
m, and the intensity of the reflected light was measured. 1 absorbance before environmental test
When the value is set to 00, the absorbance of the dye disk after the environmental test is expressed as the residual ratio (%) of the dye after the environmental test. FIG. 4 shows the relationship between the content of the nitroso compound and the aminium salt in the deterioration inhibitor in the recording layer and the residual ratio of the dye on the dye disk. The dye discs of Examples 1-3 and Comparative Example 1 having an aminium salt content of 25% or more were used in the above environment for 50 minutes.
The absorbance of the disk was slowly changed even after 0 hours, whereas the dye disk E of Comparative Example 2 in which the deterioration inhibitor was only a nitroso compound had a significantly reduced absorbance after 500 hours. . In addition, when the nitroso compound is contained in the deterioration inhibitor in an amount of 25% or more, the deterioration inhibitor exhibits light resistance and storage stability equivalent to those of the dye disk D composed of 100% aminium salt. It was found that a synergistic effect was obtained by simultaneously adding.

In the above embodiment, the present invention has been described using a write-once optical disc. However, the optical recording medium of the present invention is not limited to this, and is applicable to any optical recording medium containing an organic dye in the recording layer. It is possible.

[0043]

According to the optical recording medium of the present invention, the recording layer contains a nitroso compound and an aminium salt at the same time as an additive, so that it has excellent light resistance and storage stability and can maintain a high reflectance with respect to reproduction light. it can.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of an optical recording medium according to an embodiment of the present invention.

FIG. 2 is a plan view of an optical recording medium according to an embodiment of the present invention.

FIG. 3 is a graph showing the relationship between the addition amount of a nitroso compound and an aminium salt of an optical recording medium and the reflectance of an optical disk according to examples and comparative examples of the present invention.

FIG. 4 is a graph showing the relationship between the amount of a nitroso compound and an aminium salt added to an optical recording medium and the remaining amount of a cyanine dye after a light exposure test according to Examples and Comparative Examples of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Transparent substrate 2 Dye layer 3 Reflective layer 4 Protective layer 5 Guide groove 6 Pit 7 Center hole 8 Track 10 Optical recording medium

Claims (6)

[Claims] 1. An optical recording medium having a recording layer containing a cyanine-based organic dye on a substrate, wherein the recording layer contains a nitroso compound and an aminium salt. 2. The method according to claim 1, wherein the nitroso compound is represented by the following general formula (1):
The optical recording medium according to claim 1, wherein the aminium salt is a compound represented by the following general formula (2). Embedded image (Wherein, R may be the same or different, and represents a kind selected from the group consisting of an alkyl group, an aromatic hydrocarbon group, and hydrogen.) (Wherein, R may be the same or different and each represents an alkyl group, an aromatic hydrocarbon group or hydrogen, and X ⁻ is a group consisting of an organic anion, a halogen ion, a metal complex ion and a halide ion. Indicate the kind to be chosen,
n is 1 or 2. ) 3. The optical recording according to claim 1, wherein the cyanine-based organic dye is one selected from the group consisting of compounds represented by the following general formulas (3), (4) and (5). Medium. Embedded image Wherein Y is a group of atoms forming a benzene ring or a substituted benzene ring, and R ₁ , R ₂ , R ₃ , R ₄ , R ₅ and R ₆ are
Each may be the same or different represents a hydrogen atom, an alkyl group, an alkoxyl group, an alkyl hydroxy group, an aralkyl group, an alkenyl group, a one selected from the group consisting of alkyl carboxyl group and an alkylsulfonyl group, A ^- is an organic One kind selected from the group consisting of anions, halogen ions, metal complex ions and halide ions is shown. ) (Wherein, Z is a group of atoms forming a naphthalene ring or a substituted naphthalene ring, and R ₁ , R ₂ , R ₃ , R ₄ , R ₅ and R ₆
, Respectively, it may be the same or different represents a hydrogen atom, an alkyl group, an alkoxyl group, an alkyl hydroxy group, an aralkyl group, an alkenyl group, a one selected from the group consisting of alkyl carboxyl group and an alkylsulfonyl group, A ^- Represents a kind selected from the group consisting of organic anions, halogen ions, metal complex ions and halide ions. ) (Wherein, Y represents an atom group forming a benzene ring or a substituted benzene ring, Z represents an atom group forming a naphthalene ring or a substituted naphthalene ring, and R ₁ , R ₂ , R ₃ , R ₄ , R
₅ and R ₆ may be the same or different and each is a kind selected from the group consisting of a hydrogen atom, an alkyl group, an alkoxyl group, an alkylhydroxy group, an aralkyl group, an alkenyl group, an alkylcarboxyl group and an alkylsulfonyl group. Yes, A ^- is an organic anion, a halogen ion,
Shows one selected from the group consisting of metal complex ions and halide ions. ) 4. The recording layer according to claim 1, wherein the cyanine dye is 40 to 97.
% By weight of a mixture of a nitroso compound and an aminium salt
60% by weight, and the weight mixing ratio of the nitroso compound and the aminium salt is 2
2. The ratio is 0/80 to 80/20.
The optical recording medium according to any one of claims 1 to 3. 5. The weight mixing ratio of the nitroso compound and the aminium salt is as follows: nitroso compound / aminium salt = 50/5.
The optical recording medium according to claim 4, wherein the optical recording medium has a ratio of 0 to 25/75. 6. The write-once optical recording medium according to claim 1, wherein the optical recording medium is a write-once optical recording medium in which a recording layer, a reflective layer, and a protective layer are sequentially laminated on a substrate. Optical recording medium.