JPH074975B2 - 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 optical information recording medium in the heat mode is created by vacuum-depositing a low-melting metal such as tellurium on an insulating substrate, and when recording on this, for example, a signal of an image taken by a camera 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
It is known to use a material that has a substrate incident reflectance ((absolute reflectance of an optical information recording medium obtained by irradiating a reproduction laser beam from the plastic substrate side) of 30% or more for a 10 nm semiconductor laser. Absent.

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 alkylhydroxy group or an alkylcarboxy group, X ₂ ⁻ is a halogen atom, an anion such as perchloric acid, borofluoric acid, toluenesulfonic acid or alkylsulfonic acid. indicated by representing) a, R _2, R ₂ is a typical example _{': C 2 H 5, X} 2 -:. I - a recording layer by using a cyanine dye on the plastic substrate (refractive index 1.5) is The wavelength dependence of the maximum substrate incident reflectance (maximum reflectance obtained by optimizing the film thickness of the dye layer) of the provided optical information recording medium is as shown in FIG. As can be seen from FIG. 4, an optical information recording medium using a cyanine dye, which has been conventionally said to have a high reflectance, also has a maximum peak (wavelength 88 in the semiconductor laser wavelength range of 750 to 810 nm).
The reflectance will be about half that of the 0 nm).

On the other hand, it is known that the maximum absorption wavelength of the cyanine dye changes depending on the length of the methine chain, and it is considered that the wavelength dependence of the maximum substrate incident reflectance also changes with the change of the maximum absorption wavelength. So, the methine chain is bentamethine (
CH = CH ₂ CH =) is a typical example of indigo carbocyanine dye An optical information recording medium in which the recording layer using was prepared was provided on a plastic substrate, and the wavelength dependence of the maximum substrate incident reflectance was examined, and the result was as shown in FIG. This fifth
As can be seen from the figure, the maximum peak of the maximum substrate incident reflectance shifts to the short wavelength side when the methine chain is shortened, but 750 to 810 nm
The reflectivity in the semiconductor laser wavelength range is not improved.

In any case, if 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 required for the optical system and the electrical system in order to obtain a sufficient C / N.
There is also a problem that it cannot be played on a general CD (compact disc) player.

An object of the present invention is to optimize the molecular structure of a cyanine dye, thereby making it possible to obtain the maximum substrate incident reflectance in the semiconductor laser wavelength range of 750 to 810 nm, for example, optical information recording with high reflectance of 40% or more. It is to provide a medium, and to provide an optical information recording medium that can be reproduced with good performance even on a general CD player.

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, A, A 'represents a benzene ring with a substituent a phenyl ethylene group, R _1, R _1' represents an alkyl sulfonic acid group bound to an alkyl group or an alkali metal ion or an alkyl group, X ₁ ^- Represents an anion of a halogen atom, perchloric acid, fluoroboric acid, or toluenesulfonic acid, and when R ₁ and R ₁ ′ have a group bonded to an alkali metal ion, X ₁ ⁻ does not have to exist. ) Next, the present invention will be described in detail.

The present inventors have found that 2 × 10 ⁻⁵ mol / indolenine cyanine
The wavelength between the maximum absorption wavelength of the dimethylformamide solution measured by the spectrophotometer and the wavelength that maximizes the maximum substrate incident reflectance of the optical information recording medium having the recording layer formed on the plastic substrate using this cyanine dye is shown in FIG. We found that there is a good correlation, as shown in, from now on, 750-810
In order to obtain the maximum substrate incident reflectance in the laser wavelength region of nm, it is understood that the maximum absorption wavelength of the above solution is in the range of 640 to 720 nm.

On the other hand, the present inventors have found that in the indolenine dicarbocyanine composed of pentamethine or substituted pentamethine, the maximum absorption wavelength changes as shown in FIG. 3 by changing the substituents A and A '.

Therefore, referring to FIGS. 2 and 3, appropriate substituents A and A ′ are selected and 2 × 10 ⁻⁵ mol / indolenine dicarbocyanine having the substituents A and A ′ is selected. Maximum absorption wavelength of 640 to 720 for dimethylformamide solution
It can be seen that the optical information recording medium having the maximum substrate incident reflectance in the semiconductor laser wavelength range of 750 to 810 nm can be produced by setting the wavelength in the range of nm.

Examples of the substituents A and A'include a substituted benzene ring, and examples of the substituent include a phenylethylene group.

In order to manufacture the optical information recording medium according to the present invention, a dye solution in which the indolenine-based cyanine represented by the above general formula [I] is dissolved is prepared and coated on a substrate, and this dye solution contains chloroform. , 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.

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

Example 1 1,1'-dipropyl 3,3,3 ', 3' tetramethyl 5,5 'bis (1-phenyl 2 ethylene) dicarbocyanine toluenesulfonate (2.times.10.sup.- ⁵ mol / dimethylformamide solution spectroscopy (Maximum absorption wavelength of 678 nm measured by a photometer) 0.5 g was dissolved in 10 cc of benzyl alcohol, applied on a polymethylmethacrylate substrate by a spin coating method, and dried to prepare an optical information recording medium having a recording layer of 500 Å.

Using a 780 nm semiconductor laser on the obtained optical information recording medium, a signal was recorded at a linear velocity of 1.2 m / sec and a recording frequency of 0.5 MHz, the recording power was 4.5 mW, and C
/ N was 46 dB.

The reflectance of the laser incident from the substrate side was 44%.

Comparative Example 1 1,1 ', 3,3,3', 3'-Hexamethylindotricarbocyanine perchlorate (product number manufactured by Japan Photosensitive Dye Research Institute
NK2421 2 × 10 ^-5 mol / maximum absorption wavelength of dimethylformamide solution by spectrophotometer 749 nm) 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 1,1 ′, 3,3,3 ′, 3′-hexamethylindodicarbocyanine iodide (manufactured by Japan Photosensitive Dye Research Institute, product number NK52
(Maximum absorption wavelength of 630 nm measured by a spectrophotometer for 2 × 10 ^-5 mol / dimethylformamide solution at 9) 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 7 mW and the C / N during reproduction was 35 dB. The reflectance of the laser incident from the substrate side was 25%.

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.

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 disc 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 disk according to the present invention is significantly different from the conventional optical information recording medium in terms of “reproducibility”. This difference is a significant difference in practical use in that the conventional optical information recording medium is almost unreproducible by a CD player, whereas the present invention has 86% of reproducible models.

EFFECTS OF THE INVENTION According to the present invention, it is possible to provide an optical information recording medium having a recording layer using the cyanine dye of the general formula [I], so that the reflectance can be increased to, for example, 44%. As a result, a sufficient output of a large reproduced signal can be obtained. For this reason, sufficient performance can be obtained without requiring strict precision or change in the conventional optical system and electrical system.

In this way, an optical information recording medium can be manufactured by a simple method similar to the conventional method using an organic dye, and can be reproduced by a general commercially available CD player as simple as a high reflectance read-only disc. The number of models can be increased to, for example, 86%, and versatility can be enhanced to enhance practicality.

[Brief description of drawings]

FIG. 1 is a graph showing the relationship between the reflectance and the wavelength of the optical information recording medium of the present invention, and FIG. 2 is the maximum absorption wavelength of the cyanine dye solution and the maximum substrate incident reflectance of the optical information recording medium using this dye. FIG. 3 is a graph showing the relationship of the above, and FIG. 3 is a graph showing the change in the maximum absorption wavelength of the cyanine dye solution when the substituents of the substituted benzene rings A and A ′ of the above general formula [I] are changed. FIG. 5 is a graph showing the wavelength dependence of the maximum substrate incident reflectance of an optical information recording medium using a conventionally known cyanine dye, and FIG. 5 is the maximum of an optical information recording medium using another conventionally known cyanine dye. It is a graph which shows the wavelength dependence of a substrate entrance reflectance.

 ─────────────────────────────────────────────────── ─── 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, A, A 'represents a benzene ring with a substituent a phenyl ethylene group, R _1, R _1' represents an alkyl sulfonic acid group bound to an alkyl group or an alkali metal ion or an alkyl group, X ₁ ^- Represents a halogen atom, an anion of perchloric acid, fluoroboric acid, or toluenesulfonic acid, and when R ₁ and R ₁ ′ have a group bonded to an alkali metal ion, X ₁ ⁻ does not have to exist. )