JPH074982B2 - Optical information recording medium - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical information recording medium, and more particularly to a write-once type optical information recording medium in a heat mode.

Conventional technology Records data such as images such as characters and figures, or voice,
A write-once optical information recording medium in a heat mode is used as a reproducing means.

The write-once type optical information recording medium in this heat mode is created by vacuum-depositing a low-melting metal such as tellurium on an insulating substrate.When recording on this, for example, an image taken by a camera is used. A signal is converted into an optical signal by, for example, a semiconductor laser or a helium / neon laser, and is irradiated on a vacuum deposition film of tellurium, and the reflectance of the film is changed to form a pattern of this reflectance difference corresponding to an image. On the other hand, when the reading is performed, the difference in reflectance is detected by scanning with a weak laser beam, this signal is converted into an image signal, and an image is displayed.

By the way, recently, instead of using a deposited film of tellurium as described above, an organic dye such as panadyl phthalocyanine or cyanine dye, which has a lower reflectance than metal but relatively high reflectance among organic dye materials, is used as a recording layer. The optical information recording medium used has been attracting attention. The reason for this is that the recording layer can be formed by a coating method called spin coating, in which the centrifugal force of rotation is used to spread the paint dropped on the substrate to the periphery, which makes it easy to manufacture without using a vacuum system, It is suitable for high-density recording because it has excellent properties such as high heat resistance, excellent oxidation resistance and no corrosion, and low local heat conductivity that allows local heating without affecting the surrounding area. It depends.

In particular, cyanine dyes are used in the semiconductor laser light wavelength range of 700 to 900.
It is attracting attention because it exhibits high absorption and reflection at nm.

However, in the optical information recording medium having a conventional cyanine dye-based recording layer on a plastic substrate, including compact disc players, the most widely used semiconductor laser of 750 ~ 810 nm, for the semiconductor laser, The reflectance when entering from the plastic substrate side when reading and reflecting on the cyanine dye-based recording layer becomes 30% or more,
Moreover, a material having an absorptivity capable of recording with a power of 4 mW or less in a recording layer at a linear velocity of 1.2 to 1.4 m / sec and a frequency of 500 KHz has not been obtained.

For example, a general formula [III] that is well known for its high reflectance (However, R ₃ and R ₃ ′ are an alkyl group, an alkoxy group, an alkylhydroxy group or an alkylcarboxyl group, X ₂ ⁻ is a halogen atom, an anion such as perchloric acid, fluoroboric acid, toluenesulfonic acid or alkylsulfonic acid. Considering the optical information recording medium in which the recording layer 1 as shown in FIG. 6 is provided on the plastic substrate 2 by using the cyanine dye represented by the above formula, the optical characteristics of the recording layer are shown in FIG. Shown. In addition to this, the refractive index n of the plastic substrate (about 1.5)
The complex index of refraction n-ik of the recording layer of light passing through this substrate using
Is obtained as shown in FIG. When the reflectance of the recording layer is calculated from this and the film thickness of the recording layer is optimized so that it becomes the maximum reflectance, the wavelength showing the best reflectance is about 880 nm.
Therefore, the reflectance of a 780 nm semiconductor laser that is often used is only about half of this.

When the reflectance is low as described above, an error is likely to occur because the servo signal is small, or a sufficient output cannot be obtained because the reproduction signal is small. In addition, there is a problem in that strict precision and changes must be made to the optical system and the electrical system in order to obtain a sufficient C / N.

In addition, the compound represented by the general formula [IV] has one less methine chain than the above cyanine dye. (However, R ₄ and R ₄ ′ are an alkyl group, an alkoxy group, an alkylhydroxy group or an alkylcarboxyl group, X ₄ ⁻ is a halogen atom, perchloric acid, fluoroboric acid, toluenesulfonic acid, an alkylsulfonic acid, or the like. An optical information recording medium having a recording layer is prepared by using a cyanine dye represented by
When n-ik is obtained, the result is as shown in Fig. 3. If the maximum reflectance is obtained from this in the same way as above, the peak is 78
It is at 0 nm, but this time 4 mW under the above conditions due to lack of absorption
With the following low power, it becomes impossible to record a good quality signal.

As described above, the optical information recording medium using the cyanine dye by the conventional method has a low reflectance with respect to the wavelength of the semiconductor laser and a low absorption thereof, and no one satisfying both requirements has been obtained.

Also, due to its low reflectance, it cannot be played on ordinary CD (compact disc) players.

The object of the present invention is that it can be used with a general CD player.
It is to realize an optical information recording medium having a reflectance of not less than 100% and having absorptivity suitable for a low power laser by using a cyanine dye.

Means for Solving the Problems In order to solve the above problems, the present invention provides an indolenine-based cyanine represented by the following general formula [I] on a transparent substrate,
In an optical information recording medium having a recording layer containing a compound represented by the following general formula [II], an optical information recording medium having a reflectance of laser light of 750 to 810 nm incident from the substrate side of 40% or more, It is provided.

(However, A and A'represent a substituted benzene ring or a naphthalene ring, B is pentamethine (-CH = CH-CH = CH-CH =) or substituted pentamethine, and has a cyclic side chain extending over a plurality of carbons. R ₁ and R ₁ ′ each represent an alkyl group or an alkylsulfonic acid group bonded to an alkali metal ion or an alkyl group, and X ₁ ⁻ represents a halogen atom, perchloric acid, fluoroboric acid, benzenesulfonic acid. represents an anion of toluene sulfonic acid, R _1, R ₁ 'is X ₁ when having a group bonded with alkali metal ions ^- may not exists). (However, R ₂ is a hydrogen atom or an alkyl group, and X ₂ ⁻ represents an anion such as a halogen atom, perchloric acid, fluoroboric acid, antimony fluoride, or arsenic fluoride.) Next, the present invention will be described. The details will be described.

The present invention is directed to an indolenine cyanine dye having a high reflectance represented by the above general formula [I] and a general formula [II] having good absorption.
The two properties can be satisfied together by using the compound represented by

That is, the refractive index n, k of the recording layer made of the cyanine dye of the general formula [I], for example, FIG. 3 and the refractive index n, k of the recording layer made of the metal complex dye of the general formula [II], for example, FIG. It is possible to form the recording layer as shown in FIG. 1 which is calculated based on the additivity.

Examples of the substituents A and A'of the cyanine dye of the general formula [I] that can be used in the present invention include a substituted benzene ring or a naphthalene ring, and examples of the substituent include an alkyl group, an alkoxy group, a hydroxy group, a carboxyl group, Halogen atom,
Allyl group, alkylcarboxyl group, alkylalkoxy group, aralkyl group, alkylcarbonyl group, sulfonate alkyl group bonded to metal ion, nitro group, amino group, alkylamino group, aryl group, phenylethylene group, and further Further, a combination of a plurality of indolenine type cyanines having each of these substituents can also be used, and examples of the substituents A and A'of these substances include the following.

Further, the cyclic side chain of B in the above general formula [I] is bonded to a plurality of carbons of a pentamethine chain, for example, between the second and fourth carbons to form, for example, a 4-membered ring, a 5-membered ring and a 6-membered ring. A bonding chain composed of carbon and other atoms may be mentioned, and B may have a substituent. This substituent includes a halogen atom, a diphenylamino group, an alkoxy group (eg, a lower alkoxy group such as methoxy and ethoxy), an alkyl group (eg, methyl,
And lower alkyl groups such as ethyl).

Specifically, in addition to those mentioned in the examples below, the following can be exemplified.

The synthesizing methods for these are The Chemistry of Syn
The ones listed in thetic Dyes Vol 4 can be used.

Specific examples of the compound of the above general formula [II] include the following compounds in addition to those described in the examples below.

An example of the production of the above compound is IR manufactured by Nippon Kayaku Co., Ltd.
G002 is mentioned.

To manufacture the optical information recording medium of the present invention, a dye solution in which the indolenine-based cyanine represented by the general formula [I] and the compound represented by the general formula [II] are dissolved is prepared and used as a substrate. The dye solution may be chloroform, dichloroethane, methylethylketone, dimethylformamide, methanol, toluene, cyclohexanone, acetylacetone, cellosolves such as methylcellosolve, dioxane and the like. In this case, the mixing ratio of the cyanine dye is preferably 1% to 10%.

Further, glass, epoxy resin, methacrylic resin, polycarbonate resin, polyester resin, polyvinyl chloride resin or the like can be used for the substrate used in the present invention.

Further, it is preferable to use a spin coating method to apply the cyanine dye solution to the substrate. In this case, as the thickness of the coating layer after drying, those conventionally used can be applied.

In the present invention, a plurality of indolenine cyanine compounds of general formula [I] and compounds of general formula [II] can be used in combination.

EXAMPLES Next, the present invention will be described in detail based on examples.

Example 1 1,1'-dibutyl 3,3,3 ', 3' tetramethyl 4,5,4 ', 5'
Dibenzoindodicarbocyanine perchlorate (product number NK3219 manufactured by Japan Photosensitive Dye Research Institute) 0.42g and N, N, N ', N'-tetrakis (p-dibutylaminophenyl) -p-phenylenediamine perchlorate (IR
G003 Nippon Kayaku Co., Ltd.) Dissolve 0.14 g in 20 cc of 1,2-dichloroethane, apply and record on epoxy resin substrate by spin coating, 500
An optical information recording medium having a recording layer of Å was prepared.

When a signal was recorded on the obtained optical information recording medium with a semiconductor laser of 780 nm at a linear velocity of 1.2 m / sec and a recording frequency of 0.5 MHz, the recording power was 3.4 mW, and the pit shape was good and during reproduction. C / N was 50 dB.

Further, the reflectance of the laser incident from the substrate side was 40%.

Example 2 1,1'diethyl 3,3,3 ', 3' tetramethyl 5,7,5 ', 7' tetramethoxy indodicarbocyanine perchlorate 0.4 g and N, N, N ', N'-tetrakis (p-diethylaminophenyl) -p-phenylenediamine fluoroborate When 0.1 g was dissolved in 10 cc of dimethylformamide and coated on an epoxy resin substrate in the same manner as in Example 1 to prepare an optical information recording medium, and recording was performed in the same manner as in Example 1, the recording power was 3.5 mW, The pit shape is good and the C / N during playback is 48 dB.
Met.

The reflectance of the laser incident from the substrate side was 42%.

Comparative Example 1 1,1 ', 3,3,3', 3 'Hexamethyl indotricabocyanine perchlorate (product number NK manufactured by Japan Photosensitive Dye Research Institute
2421) 0.5 g of ethanol was dissolved in 10 cc of ethanol, and this was applied onto an acrylic resin substrate by spin coating and dried to prepare an optical information recording medium having a recording layer of 500 Å.

Recording was also performed on the obtained optical information recording medium in the same manner as in Example 1. The recording power was 2.4 mW and the C / N during reproduction was 49 dB.

The reflectance of the laser incident from the substrate side was 28%.

Comparative Example 2 1,1 ', 3,3,3', 3 'Hexamethyl4,5,4', 5 'Dibenzoindodicarbocyanine iodide (NK2929 manufactured by Japan Photosensitive Dye Research Institute) 0.6 g was dissolved in 10 cc of dimethylformamide, and this was applied onto an epoxy resin substrate by spin coating and dried to prepare an optical information recording medium having a recording layer of 500 Å.

Recording was also performed on the obtained optical information recording medium in the same manner as in Example 1. The recording power was 4.4 mW and the C / N during reproduction was 47 dB. Further, the reflectance of the laser incident from the substrate side was 45%.

Comparative Example 3 Same as Example 1 except that 1,1'diethyl 3,3,3 ', 3' tetramethyl indotricarbocyanine iodide was dissolved in 2-nitropropane and the film thickness was 450 Å. Then, an optical information recording medium was produced. The reflectance of the laser incident from the substrate side of this optical recording medium was 28%.

Next, a practicality test was conducted.

In order to confirm whether or not the reflectance of the optical information recording media obtained in the above Examples and Comparative Examples is sufficient for reproduction by a CD player, commercially available CD players of respective reflectance cases
We investigated how many models among 22 models are reproducible (reproducibility (playability)).

The CD players used in the test are as follows.

Sony CDP-101, CDP-502ES, CDP-570, CDP-338ESD, CFP-D70 Matsushita Electric Industrial Co. SL-PA10 (Panasonic), SL-120 (Technics), SL-333
(Technics), SL-500 (Technics), SL-770 (Technic
s), SL-1200 (Technics), SL-X845 (Technics) Pioneer PD-535, PD-4700 Yamaha CD-1000 Nippon Columbia DCD-1650G Kenwood DP-8010 NEC Denki CD -410, CD-430 Nippon Victor XL-V501 Nippon Marantz CD-34 Sharp QT-35CD As an evaluation method, the focus servo and tracking servo are activated, and the TOC information can be read out and recorded. The optical information recording medium on which the recorded information could actually be reproduced was defined as "reproducible".

The percentage of the total number of CD player models that were evaluated as "reproducible" was defined as "reproducibility (playability) (%)".

The recording power is also shown as the recording power.

From the above results, it can be seen that the optical information recording medium according to the present invention is significantly different from the conventional optical information recording medium in terms of "reproducibility" and recording characteristics (specifically, recording power etc.). . This difference is not practical or requires a large recording power in the conventional optical information recording medium, whereas the optical information recording medium of the present invention can record with low power and can be reproduced by a CD player. This is a significant difference in the practical effect of 50% or more.

EFFECTS OF THE INVENTION According to the present invention, there is provided a recording layer in which the cyanine dye represented by the general formula [I] and the compound represented by the general formula [II] are used in combination, and the reflectance of the recording layer is 40%. Because of the above, the good reflection property can remarkably improve the reproduction characteristics, and at least 50% or more of the models can be reproduced by a general commercially available CD player, and the compound of the general formula [II] can be used. It is possible to provide an optical information recording medium having excellent recording characteristics such that recording can be performed with a low power of, for example, 4.0 mW or less by also having a good absorbing property.

[Brief description of drawings]

FIG. 1 is a graph showing the optical characteristics of an optical information recording medium in which the cyanine dye of the general formula [I] of the present invention and the compound of the general formula [II] are used in combination, and FIGS. 2 and 3 show different cyanine dyes. FIG. 4 is a graph showing the optical characteristics of an optical information recording medium using a dye, FIG. 4 is a graph showing the optical characteristics of a compound of general formula [II], and FIG. 5 is a graph showing the optical characteristics of an example of a cyanine dye. FIG. 6 is an explanatory diagram showing a reproduction state of the optical information recording medium.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takashi Ishiguro 1-2-12 Ueno Taito-ku, Tokyo Within Taiyo Denki Co., Ltd. (56) Reference JP-A-59-85791 (JP, A) JP-A-SHO 62-103191 (JP, A) JP-A-62-30088 (JP, A) JP-A-62-99191 (JP, A)

Claims (1)

[Claims] 1. An optical information recording medium having a recording layer containing, on a transparent substrate, an indolenine cyanine represented by the following general formula [I] and a compound represented by the following general formula [II], An optical information recording medium in which the reflectance of laser light of 750 to 810 nm incident from the substrate side is 40% or more. (However, A and A'represent a substituted benzene ring or a naphthalene ring, B is pentamethine (-CH = CH-CH = CH-CH =) or substituted pentamethine, and has a cyclic side chain extending over a plurality of carbons. R ₁ and R ₁ ′ each represent an alkyl group or an alkylsulfonic acid group bonded to an alkali metal ion or an alkyl group, and X ₁ ⁻ represents a halogen atom, perchloric acid, fluoroboric acid, benzenesulfonic acid. represents an anion of toluene sulfonic acid, R _1, R ₁ 'is X ₁ when having a group bonded with alkali metal ions ^- may not be present). (However, R ₂ is a hydrogen atom or an alkyl group, and X ₂ ⁻ represents an anion such as a halogen atom, perchloric acid, borofluoric acid, antimony fluoride, or arsenic fluoride.)