JP2003178490A - Information recording medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical recording medium, in which an organic dye recording layer and a light reflecting layer are deposited on a light transmitting substrate as a first disk, a light reflecting layer, an organic dye recording layer and a dye protective layer are deposited on a light transmitting substrate as a second disk, and the light reflecting layer of the first disk is laminated on the dye protective layer of the second disk with an adhesive layer, which attains a recording satisfactorily in the first and second disks through the light transmitting substrate side of the first disk. <P>SOLUTION: In the optical recording medium composed of the organic dye recording layer 2, the light reflecting layer 3, an adhesive layer 4, the dye protective layer 5, the organic dye recording layer 22, the light reflecting layer 32 and the light transmitting substrate 21 on the light transmitting substrate 1 as shown in Fig. 1, the decomposition temperature Tb1(°C) of the dye used in the organic dye recording layer 2 and the decomposition temperature Tb2(°C) of the dye used in the organic dye recording layer 22 satisfy the relation of 100≥Tb1-Tb2>0(°C). <P>COPYRIGHT: (C)2003,JPO

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical recording medium having a recording layer and a reflection layer on a transparent light transmitting substrate. [0002] An organic dye recording layer that absorbs laser light directly or with another layer interposed on a transparent light-transmitting substrate;
A write-once optical disc, which is an optical recording medium having a metal reflective layer directly on the recording layer or with another layer interposed therebetween, is widely known. DVD is one of the write-once optical disks.
-R. DVD-R is 4.7mm on one side with a thickness of 0.6mm
Disk with GB recording capacity, same thickness 0.6m
A single-sided recordable DVD-R with a capacity of 4.7 GB in the form of two dummy disks that cannot be written with a capacity of 4.7 m
There are two types of DVD-R, a double-sided recording type DVD-R having a capacity of 9.4 GB, in which two disks having a recording capacity of 4.7 GB on one side are bonded together, and recording and reproduction are performed using laser from both sides. [0003] The double-sided recording type DVD-R, which performs recording and reproduction using a laser from both sides, has a large capacity of 9.4 GB. However, in a recording / reproducing apparatus, a recording / reproducing laser is installed above and below the disk surface. I have to do it. For this reason, the recording / reproducing apparatus becomes expensive, and a single-sided recording type DVD-R is generally used.
R is often used. This DVD-
R has an authoring standard and a general standard, but there is no difference between them in terms of capacity. If an optical recording medium in which two disks are bonded together and recording is performed by irradiating a laser beam from one side can be produced, it can be advantageous in terms of both capacity and drive structure. However, there may be a problem in manufacturing such an optical recording medium. In an optical recording medium having an organic dye recording layer, pits are formed at a temperature at which the applied dye can be decomposed by a laser irradiated at the time of recording, and recording is performed. In an optical recording medium having an organic dye recording layer, it is necessary to consider heat interference. [0005] If the irradiated laser is insufficient in power, there are portions that are decomposed and portions that are incompletely decomposed,
Good pits are not formed. Also, if the power of the irradiated laser is applied too much, the part irradiated with the laser will become unnecessarily hot, the heat will spread outside the pits to be formed, and the dye will also decompose in the part where the heat spreads I will. Thus, the power of the laser irradiated at the time of recording must not be too strong or too weak with respect to the decomposition temperature of the dye. The dye used for the optical recording medium having the organic dye recording layer has an optimum film thickness for performing good recording. However, in an optical recording medium having an organic dye recording layer having the same structure, when the dye film thickness is changed, there is not so much a laser power difference when recording is performed so as to be optimal at each film thickness. This is because the recording of the dye depends on the decomposition temperature inherent to the dye, and pits are formed when the irradiated portion of the laser reaches the decomposition temperature due to the power of the irradiated laser. Here, in an optical recording medium in which two disks are bonded together and recording is performed by irradiating a laser from one side, the same dye is applied to the recording surface of the disk near the laser incident surface and to the recording surface of the distant disk. When recording is performed on both disks, recording is performed on both disks at different dye film thicknesses, but the temperature at which the dye is decomposed and pits are formed is the same. In such a disc, a farther disc has more layers through which the laser passes than a disc closer to the laser incident surface, so that the light amount loss is larger.
In order for the dye in the organic dye recording layer of the disk closer to the laser incident surface and the dye of the organic dye recording layer in the farther disk to decompose at the same temperature, the laser must apply a large power that takes into account the loss of light amount due to transmission through more layers. It is necessary to bring the dye in the organic dye recording layer of the distant disk to the decomposition temperature. [0008] In other words, in order to perform recording with the same power on both discs by laminating the two discs and recording by applying laser from one side, it is necessary to make the laser incident surface The decomposition temperature of the dye used on the recording surface of the far disk may be lower than that of the dye used on the near disk. As a measure of the decomposition temperature difference, it is desirable to lower the decomposition temperature of the dye used on the recording surface of the far disk by 10 ° C. or more than that of the dye used on the disk near the laser incident surface. If the decomposition temperature difference is smaller than this, the difference in recording power becomes large, and good recording becomes difficult. However, if a material having a low thermal conductivity and a material having a high transmittance at the recording wavelength that can surely suppress the heat loss is used, it is possible to reduce the decomposition temperature difference. In addition, if the decomposition temperature of the dye used on the recording surface of the far disk is lower than that of the dye used on the disk closer to the laser incident surface by 100 ° C. or more, the recording of the disk farther than the dye used on the disk close to the laser incident surface is possible. The dye used on the surface is liable to be decomposed, and the recording surface of the farther disk can be recorded with lower power than the dye used on the disk closer to the laser incident surface, which is not preferable. SUMMARY OF THE INVENTION An object of the present invention is to record data on an optical recording medium having a structure in which two single-sided recording disks are bonded by using a laser only from one side of the disk. It is an object of the present invention to provide an optical recording medium which performs the recording on both disks satisfactorily and performs recording with the same laser power when recording on both disks. Thus, it is not necessary to perform the optimum recording laser power for both disks, and the optimum recording laser power can be determined at once. Means for Solving the Problems As shown in FIG.
An organic dye recording layer 2, a light reflection layer 3,
The following method is used for an optical recording medium including the adhesive layer 4, the dye protective layer 5, the organic dye recording layer 22, the light reflection layer 32, and the light transmitting substrate 12. The decomposition temperature Tb1 (° C.) of the dye used in the organic dye recording layer 2
When the decomposition temperature Tb2 (° C.) of the dye used for
It is characterized by satisfying 0 ≧ Tb1−Tb2> 0 (° C.). By the above method, an optical recording medium excellent in good recording can be provided. Embodiments of the present invention will be described below, but the present invention is not limited to these embodiments. First,
The method of creating the first disc is described below. The light transmissive substrate 1 has a transparent material, a resin such as a polycarbonate resin, an acrylic resin, an epoxy resin, an ABS resin, or the like, a glass, or the like. A transparent resin material such as a polycarbonate resin or a polymethyl methacrylate resin can be used as the easily handled resin. The light transmissive substrate can be manufactured by injection molding of these transparent resin materials, but is not limited to this manufacturing method, and can be manufactured by 2P (Photo-Po
lymer) method. A tracking pre-groove of at least 0.3 μm is formed on at least one surface of the light transmitting substrate.
The grooves may be formed concentrically or spirally at intervals of 1.6 μm, and the groove depth of the formed pre-groove is 100 nm in order to obtain a reproduced signal amplified by utilizing the optical interference effect. It is desirable to set it to 250 nm. On the surface of the light transmissive substrate, a predetermined pattern such as a pre-pit on which information is recorded or a groove or the like for tracking or addressing is provided as necessary. The organic dye recording layer 2 is provided directly on the above-mentioned light-transmitting substrate 1 or via another inorganic or organic layer. The recording layer can be formed by a spin coating method, an evaporation method, or the like, and a spin coating method using a solvent is particularly preferable. As a solvent used at the time of film formation, for example, ethyl cellosolve, methyl cellosolve, methanol, tetrafluoropropanol, or the like can be used. The thickness of the recording layer to be formed is 20 nm to 200 nm.
Is preferred. As the dye of the dye thin film forming the organic dye recording layer, a dye having a property of causing chemical changes such as decomposition, sublimation, melting, and vaporization by irradiation of a recording laser is used. Organic dyes that meet this condition include cyanine dyes, squarylium dyes, croconium dyes,
Azulenium dyes, triarylamine dyes, anthraquinone dyes, metal-containing azo dyes, dithiol metal complex dyes, indoaniline metal complex dyes, phthalocyanine dyes, naphthalocyanine dyes, intermolecular CT complex dyes, etc. is there. In the organic dye recording layer of the present invention, these dyes may be used alone or in combination. In addition, in addition to the recording dye, an antioxidant, a quencher such as a dithiol complex, nitrocellulose, cellulose acetate, a ketone resin, an acrylic resin, polyvinyl butyral, polycarbonate, and a binder such as polyolefin are added to the organic dye recording layer. Is also good. The light reflecting layer 3 includes, but is not particularly limited to, Ag, Al, Au, Cu, Cr, Ni, Pt, Pd, etc. on the organic dye recording layer. The light reflection layer 3 can be formed by vacuum deposition, sputtering, ion plating, or the like. The thickness of the reflective layer to be formed is
0.01 μm to 0.2 μm is preferred. Next, a method for creating the second disk will be described below. A light reflecting layer 32 is formed on the light transmitting substrate 12 similar to the light transmitting substrate 1, similarly to the light reflecting layer 3. The thickness of the reflective layer to be formed is preferably from 0.1 μm to 0.2 μm. The organic dye recording layer 22 is applied on the light reflection layer 32 in the same manner as the organic dye recording layer 2. Next, the organic dye recording layer 22
The dye protective layer 5 is formed thereon. The dye protective layer includes an inorganic compound and an organic compound, but is not particularly limited. Examples of inorganic compounds include rare earths containing Yu, Au, Ag, Al, As, Ba, Be, Bi, Ca, Co, Cu, Fe, G
a, Ge, Hf, In, Mg, Ni, Pb, Pd, Rh, Sc, Si, Sn, T
Metals such as a, Ti, V, W, Zn, and Zr, and oxides, sulfides, nitrides, halides, fluorides, carbonates, sulfates, nitrates, and nitrites thereof are exemplified. Examples of the organic compound include resins such as vinyl acetate resin and vinyl chloride resin, resins such as polydimethylsiloxane, and organic substances such as sucrose, tartaric acid, paraffin and the like. When used as a separate layer, these may be used alone, or mixed and laminated. The thickness of the dye protective layer 5 to be formed is 0.
005 μm to 0.04 μm is preferred. Finally, the light reflecting layer 3 of the first disk and the dye protective layer of the second disk are bonded. As the adhesive layer 4, an organic material such as an ultraviolet-curable acrylic resin, an ultraviolet-curable resin such as an ultraviolet-curable epoxy resin, an ultraviolet-curable adhesive, an epoxy adhesive, a silicone resin, a silicone adhesive, and a hot melt adhesive is used. can do. The thickness of the protective layer is preferably from 0.1 μm to 100 μm. The adhesive layer 4 can be formed by a usual method such as spin coating, gravure coating, spray coating, roll coating and the like. Here, the decomposition temperature Tb1 (° C.) of the dye used for the organic dye recording layer 2 in the first and second discs
And the decomposition temperature Tb of the dye used for the organic dye recording layer 22
When 2 (° C.), 100 ≧ Tb1−Tb2> 0 (° C.)
Is satisfied. According to the above-described method, a light beam for performing recording and reproduction on both disks by using a laser only from one side of the disk is used for a disk having a structure in which the first and second single-sided recording disks are bonded together. It is possible to provide a recording medium. However, the decomposition temperature of the dye used in the present invention means that the temperature of the dye is from room temperature to 1 temperature in an argon atmosphere.
The temperature was raised at 0 ° C./min, and defined as the temperature at which the weight of the dye was reduced by 10%. EXAMPLES In order to specifically show the effect of the present invention,
This will be specifically described with reference to the drawings. The present invention will be specifically described with reference to examples, but embodiments of the present invention are not limited thereto. (Embodiment 1) FIG. 1 shows an example of the structure of an optical recording medium according to the present invention. First, a method for manufacturing the first disk will be described below. Using an injection molding machine equipped with a stamper on which a preformat pattern is formed, a polycarbonate resin is injection-molded to have a diameter of 120 mm.
The light transmissive substrate 1 having a thickness of 0.6 mm and a plate thickness of 0.6 mm was produced.
On the obtained light transmissive substrate 1, a pre-groove for tracking was formed concentrically with a track pitch of 0.8 μm and a groove width of 0.3 μm. On the light-transmitting substrate 1 on which the pregroove is formed, as an organic dye recording layer, 1% by weight of an azo dye having a decomposition temperature of 339 ° C. represented by the following structural formula:
Of a solution having a concentration of 2
The organic dye recording layer 2 was formed by coating at 00 nm. In addition,
When applying the dye, an azo-based dye solvent was used using tetrafluoropropanol as a solvent, and the mixture was filtered through a filter to remove insolubles. Embedded image Light transmitting substrate 1 coated with this organic dye
Was dried at 70 ° C. for 1 hour after dye application. Au was formed as a light reflection layer 3 on the organic dye recording layer 2 by sputtering to a thickness of 0.020 μm. Next, a method for creating the second disk will be described below. The light-transmitting substrate 12 on which the pregroove was formed was manufactured in the same manner as the light-transmitting substrate 1. Au was formed as a light reflecting layer 32 to a thickness of 0.1 μm on the light transmitting substrate 12 on which the pregroove was formed by sputtering in the same manner as the light reflecting layer 3. On the light reflection layer 32, an organic dye recording layer 2
2 was applied in the same manner as the organic dye recording layer 2. However, an azo dye having a decomposition temperature of 329 ° C. represented by the structural formula (Formula 2) was used as the organic dye recording layer. Embedded image On the organic dye recording layer 22, as a dye protective layer 5, Au was sputtered to a thickness of 0.015.
A film was formed with a thickness of μm. Finally, after forming the adhesive layer 4 on the light reflection layer of the first disk, the adhesive layer 4 is bonded to the dye protective layer 5 of the second disk, and irradiated with ultraviolet light of a predetermined light intensity using an ultraviolet irradiation machine. The adhesive layer 4 was cured. (Embodiment 2) to (Embodiment 3) In (Embodiment 2) and (Embodiment 3), (Chemical Formulas 2 to 4) are used for the organic dye recording layer 2 and the organic dye recording layer 22. Other than
A sample was prepared in the same manner as in (Example 1). Here, the decomposition onset temperatures of the organic dyes of Chemical Formulas 3 and 4 were 317 ° C. and 300 ° C., respectively. (Comparative Example) (Comparative Example 1) to (Comparative Example 3)
A sample was prepared in the same manner as in Example 1 except that the same organic dye was used for the organic dye recording layer 2 and the organic dye recording layer 22. (Comparative Example 4) A sample was prepared in the same manner as in (Example 1) except that (Chemical formula 1) was used for the organic dye recording layer 2 and (Chemical formula 5) was used for the organic dye recording layer 22. Produced. Here, the decomposition starting temperature of the organic dye represented by Chemical Formula 5 was 236 ° C. Embedded image Embedded image Embedded image Data recording / reproducing was performed on the optical disks of the respective samples of (Example 1) to (Example 3) and (Comparative Example 1) to (Comparative Example 4) using an optical disk evaluation device DDU1000 manufactured by Pulstec Industrial. Was. 40m radius of optical recording medium
At m, a laser beam having a wavelength of 650 nm was irradiated as a recording laser beam with a power having an optimum jitter value to record image data information. Then, the wavelength of 650 nm
Was irradiated with a power of 0.5 mW to reproduce the recorded image data information and measure the jitter value. Table 1 shows the results. [Table 1] In the samples of the present invention of (Examples 1) to (Example 3), the difference in recording power when the jitter value becomes minimum was small in the first and second disks, and good recording and reproduction were performed. Was completed. On the other hand, (Comparative Example 1) to
When the same organic dye was used for the organic dye recording layer as in (Comparative Example 3),
The recording power when the jitter became minimum was smaller for the first disk than for the second disk, and there was a large difference in the recording power. As in (Comparative Example 4), when the decomposition temperature of the dye used for the organic dye recording layer of the first and second disks is extremely low, the jitter of the first and second disks is minimized. When the recording power of the first disk becomes larger than that of the second disk, the recording power greatly differs. From the above results, the present invention, when good recording is performed on the first and second disks from the light-transmitting substrate side of the first disk, with the same laser power when recording on both disks It has been clarified that it is possible to provide an optical recording medium for recording. According to the first aspect of the present invention,
An organic dye recording layer and a light reflection layer are stacked on a light-transmitting substrate as a first disk, and a light reflection layer, an organic dye recording layer and a dye protection layer are stacked on a light-transmitting substrate as a second disk. In a recording medium in which the light reflective layer of the first disk and the dye protective layer of the second disk are bonded with an adhesive layer, recording is performed on both disks by using a laser from the light transmitting substrate side of the first disk. In addition, there is an effect that recording is performed satisfactorily, and recording is performed with the same laser power when recording on both disks.

[Brief description of the drawings] FIG. 1 is a sectional view of an information recording medium according to the present invention. [Explanation of symbols] 1 Light-transmitting substrate (first disc) 2 Organic dye recording layer (1st disc) 3 Light reflective layer disc 1) 4 Adhesive layer 5 Dye protective layer (2nd disc) 12 Light transmissive substrate (2nd disc) 22 Organic dye recording layer (2nd disc) 32 Light reflective layer (2nd disc)

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Claims (1)

Claims: 1. An organic dye recording layer and a light reflection layer are stacked on a light-transmitting substrate as a first disk, and a light reflection layer and an organic layer are formed on a light-transmitting substrate as a second disk. A dye recording layer and a dye protection layer are laminated, and the light reflection layer of the first disk and the dye protection layer of the second disk are bonded to each other with an adhesive layer. An optical recording medium that satisfies the following expression, where the decomposition temperature of the dye used is Tb1 (° C.) and the decomposition temperature of the dye used in the organic dye recording layer of the second disk is Tb2 (° C.). 100 ≧ Tb1-Tb2> 0 (° C.)