JPH10278426A - Optical recording medium - Google Patents

Abstract

[PROBLEMS] To provide a high-density optical recording medium capable of recording and reproducing with a laser light source having an oscillation wavelength in a wavelength range of 630 to 660 nm. SOLUTION: A bonding type optical recording medium 10 has a light absorption layer 14 and a reflection layer 16 on a substrate 12. The light absorbing layer 14 contains a trimethine cyanine dye represented by the following general formula (1). Embedded image In the formula (1), B and N are atoms forming a benzene ring and a naphthalene ring, respectively, and R ₁ , R ₂ , R ₃ ,
R _4, R ₅ and R ₆ are independently hydrogen atom, an alkyl group, an alkoxyl group, an alkyl hydroxy group, an aralkyl group, an alkenyl group, an alkyl carboxyl group or an alkylsulfonyl group, X ^- is a halogen ion or perchlorate Indicates an acid ion)

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical recording medium containing an organic dye in a recording film, and more particularly to a recording film containing a trimethine cyanine dye in the recording film and having an oscillation wavelength within a wavelength range of 630 to 660 nm. The present invention relates to a recordable optical recording medium on which recording and reproduction can be performed with a laser light source.

[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).
And the like, a write-once recording medium that can be written only once, and a rewritable 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: compact disc-recordable). This write-once CD has a structure in which a recording layer made of an organic dye, a reflective layer, and a protective layer are sequentially laminated on a substrate surface on which a preformat pattern is formed. Irradiates the recording layer with laser light, alters the organic dyes that make up the recording layer by the thermal energy of the laser light, changes its optical characteristics, and deforms a part of the transparent substrate that is the base of the recording part Let it. Generally, a light source for recording / reproducing such an optical recording medium has a wavelength of 770-8.
A semiconductor laser that oscillates in the near-infrared region of 30 nm is used.

Recently, an optical recording medium having a higher recording density has been developed, and the beam spot diameter has been reduced by using recording light having a shorter wavelength than the recording / reproducing wavelength of 770 nm for CD-R. Methods for increasing the recording density are being studied. Such a high-density optical recording medium can record a large amount of data such as a moving image. In recent years, DVD-Rs (digital versatile discs (also referred to as digital video discs) / recordable) have been developed.
Standardization is under way. As a recording / reproducing light source used for DVD-R which is such a high-density optical recording medium, a semiconductor laser capable of oscillating in a wavelength range of 630 to 660 nm is being studied.

[0005]

However, the recording light in the wavelength range of 630 to 660 nm is not compatible with the CD-ROM.
Organic dyes used in write-once optical recording media such as R
As a result, the semiconductor laser oscillating in the above-mentioned wavelength range cannot be reproduced because of its extremely high light absorption and insufficient reflectance.

Japanese Patent Application Laid-Open No. 6-40162 discloses a high-density optical recording medium capable of recording and reproducing with a short wavelength laser. In this optical recording medium, indocarbocyanine having an absorption wavelength band on the shorter wavelength side than 610 nm is used as the organic dye of the recording layer (FIG. 3 of the publication). Therefore, it hardly absorbs light in the wavelength range of 630 to 660 nm,
Recording cannot be performed with a semiconductor laser having an oscillation wavelength range of 630 to 660 nm.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art, and an object of the present invention is to provide a laser light source having an oscillation wavelength in a wavelength range of 630 to 660 nm. An object of the present invention is to provide a high-density optical recording medium.

[0008] A second object of the present invention is that the oscillation wavelength is 630.
A high-density optical recording medium of a bonded type capable of recording and reproducing with a laser light source existing in a wavelength range of ~ 660 nm, in particular,
An object of the present invention is to provide a write-once DVD (DVD-R).

[0009]

According to a first aspect of the present invention, in an optical recording medium having a recording layer and a reflective layer on a substrate, the recording layer is represented by the following general formula (1). Trimethine cyanine dye:

Embedded image An optical recording medium is provided, comprising:

In the formula (1), B is a group of atoms forming a benzene ring or a substituted benzene ring. The substituent when B forms a substituted benzene ring is not particularly limited. For example, an alkyl group, a halogen such as chlorine, an alkoxyl group, or the like is referred to as a solubility of the trimethine cyanine dye of the formula (1) in a solvent. It is preferred in that respect. N is an atomic group forming a naphthalene ring or a substituted naphthalene ring. The substituent when N forms a substituted benzene ring is not particularly limited. For example, an alkyl group, a halogen such as chlorine, an alkoxyl group, or the like is referred to as a solubility of the trimethine cyanine dye of the formula (1) in a solvent. It is preferred in that respect.

In the formula (1), R ₁ , R ₂ , R ₃ , R ₄ , R
₅ and R ₆ may be the same or different and represent a hydrogen atom, an alkyl group, an alkoxyl group, an alkylhydroxy group, an aralkyl group, an alkenyl group, an alkylcarboxyl group or an alkylsulfonyl group. R _{1 to} R ₄ are preferably a methyl group or an ethyl group, and R ₅ and R ₆ are preferably a propyl group, a butyl group or a pentyl group in view of the solubility of the trimethine cyanine dye of the formula (1).

[0012] X ^{- _{is, ClO 4 -, BF 4 -}} , SbF 6
^- , PF ₆ ^- or halogen such as iodine;
₄ ^- and iodine are preferred.

The trimethine cyanine dye represented by the formula (1) has an absorption band at a wavelength of 630 to 660 nm.
The recording sensitivity to the recording light of 660 nm is high,
The reflectance for the reproduction light in this wavelength range is also sufficient. Therefore, the optical recording medium of the present invention has an oscillation wavelength of 630 to 66.
Good recording / reproduction can be performed using a semiconductor laser in the wavelength region of 0 nm.

Preferred specific examples of the compound represented by the general formula (1) include the following trimethine cyanine dyes (2) to (5).

[0015]

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[0016]

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[0017]

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[0018]

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In the recording layer, another organic dye, for example, a conventionally used cyanine dye can be contained together with the trimethine cyanine dye represented by the general formula (1). By appropriately adjusting the mixing ratio of the trimethine cyanine dye represented by the general formula (1) and the other organic dye, the absorption and reflection characteristics can be optimized according to the wavelength characteristics of the recording or reproduction light. it can. As a result,
The reproduction characteristics are, for example, 633 nm, 635 nm, 638
It is possible to match with various semiconductor lasers having oscillation wavelengths such as nm, 639 nm, and 657 nm.

In the recording layer containing the trimethine cyanine dye represented by the general formula (1), the light stability of the cyanine dye is improved or the control of pit formation during recording with a semiconductor laser is facilitated. Therefore, dithiol metal complex, aminium compound, diiminium compound, nitroso compound,
An additive such as a metal thiocarbamate, a ferrocene derivative, or a metal acetylacetone complex may be added. These additives may be used alone or in combination of two or more. The usage-amount of an additive is 1-100 weight part normally with respect to 100 weight part of cyanine dyes. Further, it may be used in an amount of 100 parts by weight or more. However, since the concentration of the cyanine dye is low, the recording / reproducing characteristics of the optical recording medium may be inconvenient.

Further, an acrylic resin, a polycarbonate resin, a polyester resin, polyvinyl alcohol, etc. may be added to the recording layer as needed.

The recording layer may be formed by a dry process such as vacuum deposition or sputtering, but it is preferable to use a wet process in terms of manufacturing cost. As a wet process, for example, a trimethinecyanine dye used in the present invention is dissolved in a solvent such as methylcellosolve, ethylcellosolve, diacetone alcohol, tetrafluoropropanol, or methanol in a concentration of 1 to 10%, and a film is formed by spin coating. can do. The thickness of the recording layer is determined by considering the depth of the pit hole formed by the irradiation of the recording light and the like.
To 300 nm, more preferably 30 to 200 nm.

The optical recording medium of the present invention has at least a recording layer and a reflective layer on a substrate. Alternatively, a structure in which two substrates each having a recording layer and a reflective layer are bonded to each other with an adhesive such that the substrates are located outside may be employed.

The reflective layer can be made of any reflective material such as gold, aluminum, silver, and copper, or an alloy containing these materials as a main component, and can be formed to a thickness of about 30 to 200 nm. Further, in order to improve the reflectance, a light reflection auxiliary layer may be provided between the recording layer and the reflection layer. As a material used for the light reflection auxiliary layer, the refractive index of a substrate, particularly a polycarbonate substrate (about 1.5
9) Any material can be used as long as it is a larger material. For example, polyorganoshiroquin can be used. In this case, it can be formed by applying monomethylsiloxane or the like on the recording layer and then polymerizing it.

A protective layer can be further applied on the reflective layer, and the protective layer can be made of an inorganic material such as SiO, SiN or AlN, or an organic material such as an ultraviolet curable resin.

The substrate of the optical recording medium of the present invention can be made of any light-transmitting material, for example, a transparent resin material such as polycarbonate, polymethyl methacrylate, polymethyl pentene, epoxy, or a transparent ceramic material such as glass. Materials can be used. The substrate has a preformat pattern and a center at the center by a method such as injection molding a transparent resin material or forming a replica layer of an ultraviolet curable resin on one surface of a transparent ceramic plate (a so-called 2P method). It is processed into a disk shape with holes.

The preformat pattern includes a guide groove for causing a laser beam for recording / reproduction to follow, and prepits indicating the address of a recording track and / or a sector defined by the guide groove and a reference clock. The guide groove is formed in a spiral or concentric shape concentric with the center hole. Also, by using the guide groove as a wobble groove, various information can be detected from the cycle of the wobble groove. Further, the guide groove and the prepit can be formed at different depths. In the following optical recording medium of this example, a wobble groove was employed.

2 having each of the recording layer and the reflective layer
When manufacturing an optical recording medium of a type in which two substrates are bonded, a hot melt adhesive, an ultraviolet curing adhesive, an epoxy adhesive, a silicone adhesive, or the like can be used as an adhesive for bonding. .

According to a second aspect of the present invention, there is provided an optical recording medium having a structure in which two substrates on each of which a recording layer and a reflective layer are formed are bonded so that the substrates are located outside. An optical recording medium characterized in that the recording layer has a trimethine cyanine dye.

The trimethinecyanine dye used in the recording layer of the laminated optical recording medium of the present invention includes indocarbocyanine dye, thiocarbocyanine dye, quinothiocarbocyanine dye, quinocarbocyanine dye, quinothiocarbo dye. Cyanine dyes, oxacarbocyanine dyes and the like can be mentioned, and among them, the trimethine cyanine dye represented by the general formula (1) is preferable.

[0031]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the optical recording medium according to the present invention will be specifically described below with reference to the drawings.

Embodiment 1 FIG. 1 shows an example of the structure of an optical recording medium according to the present invention.
This optical recording medium 10 has a recording layer 14 (1 ′) on a surface of a transparent substrate 12 (12 ′) on which a wobble groove 22 is formed.
4 ′), the reflective layer 16 (16 ′) and the protective layer 18 (1
8 ′) are laminated to each other via an adhesive layer 20 as shown in FIG. The optical recording medium 10 was manufactured as follows.

The transparent substrate 12 was produced by injection molding a polycarbonate resin using an injection molding machine equipped with a stamper on which a predetermined pattern was formed. The obtained polycarbonate substrate has a preformat pattern formed on one surface thereof and has a diameter of 120 mm and a thickness of 0.6 mm.
The preformat pattern includes a wobble groove for allowing a recording / reproducing laser beam to follow, and a recording track (track pitch of 0.8) defined by the wobble groove.
μm), and pre-pits indicating the address of the sector and the reference clock.

3 parts by weight of the trimethine cyanine dye represented by the above structural formula (2) was dissolved in 100 parts by weight of ethyl cellosolve, and filtered using a membrane filter having a pore size of 0.25 μm to prepare a dye solution. . This solution is
The recording layer 14 (1) having an average film thickness of 80 nm by being applied to the polycarbonate substrate 12 (12 ′) by spin coating.
4 ′). Gold is sputtered on this to form a film with a thickness of 10
A reflective layer 16 (16 ') having a thickness of 0 nm was formed, and then a protective layer 18 (18') having a thickness of 3 μm was formed using an ultraviolet curable resin. The two laminates thus produced were bonded together with an ultraviolet-curable adhesive 20 so that their protective layers 18 and 18 'were on the inside, to obtain an optical disk having the structure shown in FIG.

Example 2 In place of the trimethine cyanine dye represented by the structural formula (2) used in Example 1, 2.4 parts by weight of the trimethine cyanine dye represented by the structural formula (3) was used. An optical disc was produced in the same manner as in Example 1 except that 0.6 parts by weight of IRG002 manufactured by Nippon Kayaku Co., Ltd. was used as the aminium compound to form a recording layer having an average film thickness of 90 nm.

Example 3 Instead of 3 parts by weight of the trimethine cyanine dye represented by the structural formula (2), 2 parts by weight of the trimethine cyanine dye represented by the structural formula (2) and another cyanine dye 1 , 1'-Dibutyl-3,3,3 ', 3'-tetramethyl-4,5-
Average thickness of 110 nm using 1 part by weight of 4 ', 5'-dibenzo-2,2'-indocarbocyanine perchlorate
An optical disc was manufactured in the same manner as in Example 1, except that the recording layer was formed.

Example 4 Instead of 3 parts by weight of the trimethine cyanine dye represented by the structural formula (2), 2 parts by weight of the trimethine cyanine dye represented by the structural formula (3) and another cyanine dye 1 , 1'-Dibutyl-3,3,3 ', 3'-tetramethyl-2,2'
Example 1 except that a recording layer having an average film thickness of 100 nm was formed using 1 part by weight of indocarbocyanine bromide.
An optical disk was produced in the same manner as described above.

Comparative Example 1 Instead of 3 parts by weight of the trimethine cyanine dye represented by the structural formula (2), 1,1′-dibutyl-3,3,3 ′, 3 ′
An optical disk was produced in the same manner as in Example 1, except that 3 parts by weight of -tetramethyl-2,2'-indocarbocyanine bromide was used.

The optical disks of Examples 1 to 4 and Comparative Example 1 were converted to 8-16 signals at a linear velocity of 3.8 m / s using an optical disk evaluation device DDU1000 manufactured by Pulstec Industrial equipped with a semiconductor laser having a wavelength of 639 nm. Recorded. After recording, the signal was reproduced using the same evaluation device, and the reflectance (Itop
) And the degree of modulation (I ₁₄ / Itop). In Table 1,
The reflectances (Ito) of the optical disks of Examples 1 to 4 and Comparative Example 1
p) and the degree of modulation (I ₁₄ / Itop), respectively.

[0040]

[Table 1]

As can be seen from the experimental results shown in Table 1, the optical disk of the comparative example has a very low degree of modulation and has insufficient recording sensitivity. On the other hand, the optical disks of Examples 1 to 4 using the trimethine cyanine dyes represented by the structural formulas (2) and (3) for the recording layer had higher reflectivity than the optical disk of the comparative example using the conventional cyanine dye. Is slightly lower, but has a sufficient reflectance (45% or more) necessary for reproducing a recording signal, and has a very high degree of modulation.

Further, the conventional cyanine dyes 1,1 ′
-Dibutyl-3,3,3 ', 3'-tetramethyl-4,
Recording layer obtained by mixing 5-4 ', 5'-dibenzo-2,2'-indocarbocyanine perchlorate and the like and trimethine cyanine dyes represented by structural formulas (2) and (3) at an appropriate mixing ratio. By using it inside, the reflectance and the degree of modulation can be adjusted appropriately. From this, if the mixing ratio of the trimethyl cyanine dye and other cyanine dyes used in the present invention is adjusted according to the specific monochromatic light (specific wavelength) of the laser used for the recording / reproducing light, the wavelength of 630 to 660 nm is obtained. At any wavelength in the range, it is possible to obtain recording sensitivity and reflectance required for recording / reproducing.

Although the optical recording medium of the present invention has been described with reference to the embodiments, the present invention is not limited thereto, and it goes without saying that the present invention includes modifications and improvements of the above embodiments. In Examples 3 and 4, specific conventional trimethine cyanine dyes were used as a mixture, but any dye can be used. Further, the optical recording medium of the embodiment has a two-sheet bonding structure as shown in FIG. 1 and the light absorbing layers 14 and 14 ′ are provided on the respective substrates, but the light absorbing layers are provided only on one of the substrates. A so-called dummy structure may be provided in which the light absorption layer is not provided on the other substrate.

[0044]

According to the optical recording medium of the present invention, since the recording layer contains a trimethinecyanine dye represented by the general formula (1) and having an absorption band at a wavelength of 630 to 660 nm, the oscillation wavelength range is 630 to 660 nm. Recording and reproduction using a semiconductor laser belonging to a light source as a light source enables high-density recording with good recording sensitivity and a reproduction signal with sufficient intensity. Further, by using a trimethine cyanine dye, particularly a trimethine cyanine dye represented by the general formula (1), in a recording layer of a laminated optical recording medium, a recording medium having a high density and a high storage capacity is provided. be able to.

In the recording layer of the optical recording medium of the present invention, a trimethine cyanine dye represented by the general formula (1) is mixed with another organic dye, for example, a conventionally used cyanine dye. By appropriately adjusting the mixing ratio of these dyes, the absorption and reflection characteristics can be optimized according to the specific wavelength of the recording or reproduction light.

[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.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Optical recording medium 12 Transparent substrate 14 Recording layer 16 Reflective layer 18 Protective layer 20 Adhesive layer

Claims (5)

[Claims] An optical recording medium having a recording layer and a reflective layer on a substrate, wherein the recording layer has a trimethine cyanine dye represented by the following general formula (1): (In the formula (1), B is a group of atoms forming a benzene ring or a substituted benzene ring, N 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 may be the same or different and represent a hydrogen atom, an alkyl group, an alkoxyl group, an alkylhydroxy group, an aralkyl group, an alkenyl group, an alkylcarboxyl group or an alkylsulfonyl group;
^{- _{is, ClO 4 -, BF 4 -}} , SbF 6 -, PF 6 - or optical recording medium, characterized in that it comprises a a halogen iodine). 2. The compound represented by the formula (1), wherein the trimethine cyanine dye is represented by the following formulas (2) to (5): Embedded image Embedded image Embedded image The optical recording medium according to claim 1, wherein 3. The trimethine cyanine represented by the general formula (1), wherein the recording layer further contains another organic dye, and the absorption and reflection characteristics of recording light or reproduction light at a specific wavelength are optimized. 3. The optical recording medium according to claim 1, wherein a mixing ratio between the dye and the other organic dye is adjusted. 4. A structure in which at least two substrates on which a recording layer and a reflection layer are formed are bonded so that the substrates are respectively disposed outside.
4. The optical recording medium according to any one of 3. 5. An optical recording medium having a structure in which two substrates on each of which a recording layer and a reflective layer are formed are bonded so that the substrates are respectively disposed outside, wherein the recording layer includes trimethine. An optical recording medium comprising a cyanine dye.