JPH074976B2 - 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, 750 to 8
There is no known example of using a material having a reflectance of 30% or more when entering a semiconductor laser of 10 nm from the plastic substrate side when reading and reflecting it on the cyanine dye recording layer.

For example, a general formula [II] that is well known for its high reflectance (However, R ₂ and R ₂ ′ are an alkyl group, an alkoxy group, an alkylhydroxyl group or an alkylcarboxyl group, X ₂ ⁻ is a halogen atom, perchloric acid, fluoroboric acid, toluenesulfonic acid, an alkylsulfonic acid, or the like. An optical information recording medium in which a recording layer is formed on a plastic substrate by using a cyanine dye represented by (4), and a recording layer of light passing through this substrate by using the refractive index n (about 1.5) of the plastic substrate. When the complex index of refraction n-ik of is calculated, the reflectance of the recording layer is calculated from this, and the film thickness is optimized so that it becomes the maximum reflectance, the wavelength showing the best reflectance is about 880 nm, which is often used. The reflectivity of the known 780 nm semiconductor laser 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. There is also the problem that strict precision and changes must be made to the optical system and electrical system in order to obtain a sufficient C / N.
(Compact disc) There is also a problem that it cannot be played on a player.

The object of the present invention can be used for general CD players.
Another object of the present invention is to provide an optical information recording medium having a cyanine dye-based recording layer having a reflectance of at least%.

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

(However, R ₁ and R ₁ ′ 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, or toluenesulfonic acid. Represents an ion, and when R ₁ and R ₁ ′ have a group bonded to an alkali metal ion, X ₁ ⁻ may not be present, B is pentamethine (CH═CH ₂ CH═) or substituted pentamethine, and It may have a cyclic side chain extending between carbons.) Next, the present invention will be described in detail.

In the present invention, the compound represented by the above general formula [I] is used, but the cyclic side chain of B is bonded to a plurality of carbons of a pentamethine chain, for example, between the second and fourth carbons, and for example, a 4-membered ring, 5 Examples of the bonding chain include carbon and other atoms forming a member ring and a 6-membered ring, and B may have a substituent.
Examples of this substituent include a halogen atom, a diphenylamino group, an alkoxy group (for example, a lower alkoxy group such as methoxy and ethoxy), an alkyl group (for example, a lower alkyl group such as methyl and ethyl).

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

In order to manufacture the optical information recording medium of the present invention, a dye solution in which the indolenine-based cyanine represented by the above general formula [I] is dissolved is prepared and applied to a substrate. Dichloroethane, methyl ethyl ketone, dimethylformamide, methanol, toluene, cyclohexanone, acetylacetone, cellosolves such as methyl cellosolve, dioxane and the like can be used. In this case, the mixing ratio of the cyanine dye is 1% to 10
% Is preferred.

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.

Further, the recording layer applied in the present invention may contain other compounds such as a singlet oxygen quencher and a light absorber.

Further, in the present invention, a plurality of compounds of the above general formula [I] 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) Dissolve 0.5 g in 10 cc of ethanol, apply on the polymethylmethacrylate substrate by spin coating method and dry,
An optical information recording medium having a recording layer of Å was prepared.

When a signal was recorded at a linear velocity of 1.2 m / sec and a recording frequency of 0.5 MHz using a semiconductor laser of 790 nm on the obtained optical information recording medium, the recording power was 4.2 mW, and the pit shape was good at the time of reproduction. C / N was 48 dB.

Further, the reflectance of the laser incident from the substrate side was 45%.

Example 2 1,1'-Dimethyl 3,3,3 ', 3' Tetramethyl 4,5,4 ', 5'
-Dibenzoindodicarbocyanine iodide (product number NK2929 manufactured by Japan Photosensitive Dye Research Institute) Dissolve 0.6g in 10cc of dimethylformamide, apply by spin coating on epoxy resin substrate and dry to 500Å
An optical information recording medium having the recording layer of No. 1 was produced.

When recording was performed on the obtained optical information recording medium in the same manner as in Example 1, the recording power was 4.4 mW, the pit shape was good, and the C / N during reproduction was 47 dB.

Further, the reflectance of the laser incident from the substrate side was 45%.

Example 3 1,1'-diethyl 3,3,3 ', 3' tetramethyl 10-chloro 9,1
1 ethylene 4,5,4 ', 5'-dibenzoindodicarbocyanine perchlorate 0.4 g was dissolved in 10 cc of 1,2-dichloroethane, applied on an epoxy resin substrate by spin coating and dried to prepare an optical information recording medium having a recording layer of 500 liters.

When recording was performed on this obtained optical information recording medium in the same manner as in Example 1, the recording power was 4.5 mW, the pit shape was good, and the C / N during reproduction was 45 dB.

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

Comparative Example 1 1,1 ', 3,3,3', 3'-Hexamethylindotricarbocyanine perchlorate (product number manufactured by Japan Photosensitive Dye Research Institute
NK2421) An optical information recording medium was produced in the same manner as in Example 1 except that was used. When recording was performed on this obtained optical information recording medium in the same manner as in Example 1, the recording power was 2.4 mW,
The C / N during playback was 49 dB. The reflectance of the laser incident from the substrate side was 28%.

Comparative Example 2 Same as Example 1 except that 1,1'diethyl 3,3,3 ', 3' tetramethylindotricarbocyanine 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.

Whether the above-mentioned reflectance of the optical information recording media obtained in the above Examples and Comparative Examples is sufficient for a CD player. How many models are reproducible among 22 commercially available CD players of each company for each reflectance? (Reproducibility (playability))
I checked.

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) (%)".

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”. This difference means that the conventional optical information recording medium can hardly be reproduced by a CD player, whereas the present invention has a reproducible model of 70% or more, which is a significant difference in practical use.

EFFECTS OF THE INVENTION According to the present invention, the recording layer using the cyanine dye of the general formula [I] is provided on the transparent substrate, and the reflectance when the laser light from the substrate side is incident is 40% or more. , A large enough reproduction signal can be obtained, sufficient C / N can be obtained without requiring severe precision or change in the conventional optical system and electric system, and it is the same as a high reflectance read-only disc. It is possible to increase the number of models that can be played on a simple commercial CD player to at least 70%,
Its practicality can be remarkably enhanced.

Further, the optical information recording medium can be produced by a simple method similar to the conventional method using an organic dye.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shin Ariake 1-22-1 Ueno Taito-ku, Tokyo Within Taiyo Denki Co., Ltd. (56) Reference JP-A-59-85791 (JP, A)

Claims (1)

[Claims] 1. An optical information recording medium having a recording layer containing an indolenine type cyanine represented by the following general formula [I] on a transparent substrate, and 750 to 810 incident from the substrate side.
An optical information recording medium having a laser light reflectance of nm of 40% or more. (However, R ₁ and R ₁ ′ 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, or toluenesulfonic acid. Represents an ion, and when R ₁ and R ₁ ′ have a group bonded to an alkali metal ion, X ₁ ⁻ may not be present, B is pentamethine (CH═CH ₂ CH═) or substituted pentamethine, It may have a cyclic side chain extending over a plurality of carbons.)