JPH045082A - Optical recording medium - Google Patents

Abstract

PURPOSE:To obtain an optical recording medium excellent in optical recording certainly forming a J-association in its recording film by adding a specific cyanine dye and a film forming aid to the recording film in specific amounts corresponding to the number of the methine groups of the dye. CONSTITUTION:An optical recording medium has a recording film on its substrate and the recording film is an LB film containing a cyanine dye represented by general formula [1] and a film forming aid so that the mixing mol ratio of the dye and the aid becomes (1:n-0.2)-(1:n+0.2 corresponding to the number (n) of the methine groups of the dye. In the case of a dye wherein the number (n) of methine groups is, for example, n=0, the mol ratio of the aid is 0.8-1.2 per 1mol of the dye. When this value is below 0.8mol. and exceeds 1.2mol, no J-association is formed in both cases and a film suitable for optical recording is not obtained and trouble not withstanding practical use is generated. As the substrate, a material, for example, glass or an org. polymer is used. By this method, an optical recording medium having a recording film forming a J-association and capable of obtaining a sleep absorption peak can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an optical recording medium, particularly an LB containing an organic dye.
The present invention relates to an optical recording medium having a film as a recording film.

[Conventional technology]

In recent years, so-called Langu has been developed as one of the thin film deposition technologies.
An organic ultra-thin film called mnir-Blodjet film (LB film) is suddenly attracting attention. This material has excellent characteristics such as good molecular control, diversity of molecules used as raw material, and ability to form a film at room temperature and normal pressure, and its application in various fields is being studied.

In particular, when this LB film is applied to the recording film of an optical recording medium, (1) By forming the LB film under predetermined conditions, so-called J-aggregates are formed, and these J-aggregates are exposed to recording light. Recording can be performed using the phenomenon of decrease in absorbance caused by spot-wise destruction.

■As a so-called wavelength multiplexing optical recording medium in which several types of dye LB films are sequentially laminated on a substrate, the film thickness is extremely thin.
This has the advantage that the entire layered dye LB film falls within the depth of focus of the laser beam, making it easier to control the focus of the laser beam.

[Problem to be solved by the invention]

When creating such an LB film, the quality of the film,
In particular, regarding the formation of J-aggregates, important factors include the aqueous phase used to develop the monomolecular film, how to apply surface pressure, and the film formation speed. The mixing ratio of the film-forming aids used is also an important factor.

However, there has been no equivalent research report on the mixing ratio of a dye and a film-forming aid mixed with the dye, and there is a demand for a proposal on the correlation between them.

In view of these circumstances, the present invention provides an optical recording medium having a recording film in which a dye and a film-forming auxiliary agent are mixed to form J-aggregates and to obtain a film having an expedited absorption peak. It is about providing.

[Means to solve the problem]

In order to solve the above problems, the present invention provides an optical recording medium having a recording film on a substrate, wherein the recording film is a cyanine dye represented by the following general formula (wherein R1 and R2 represent an alkyl group, X represents a counter ion, A is o
. The mixing ratio is 1:n-0, 2 to 1: corresponding to the number n of methine groups in the dye.
It was configured so that it was contained at a ratio of n+0.2.

For the substrate used in the present invention, materials such as glass and organic polymers are used.

A recording film laminated by the LB peritoneal formation method is provided on such a substrate, and this recording film contains a cyanine dye represented by the following general formula [1].

General formula [l Convenience arises.

Specific examples of the dyes used in the present invention include cyanine dyes represented by the following structural formulas [D-1] to [D-3].

[D-1] In the above general formula [1], R and R2 are each,
It represents an alkyl group and usually has about 16 to 20 carbon atoms. X represents a so-called counter ion, and specific examples include I and CIO. A is O, S, C (
CH3) represents a - group selected from . n is 0
Or indicates an integer of 1. If the value of n exceeds 1, the carbon chain connecting the two 5-membered rings constituting the dye represented by the general formula First, when creating the LBB described later, the so-called J-
II! H37 Furthermore, the recording film of the present invention contains a film-forming auxiliary agent. As the film-forming aid, long-chain fatty acids, derivatives thereof, and the like are used alone or in combination.

Among these, it is particularly preferable to use long-chain fatty acids.

Furthermore, the number of carbon atoms to be used among these long chain fatty acids can be appropriately determined depending on R1°R2 of the cyanine dye.

The content ratio of such a film-forming auxiliary agent is set in consideration of the number of carbon atoms in the carbon chain connecting the two five-membered rings constituting the dye, that is, the number n of methine groups.

That is, the mixing molar ratio of the dye and the auxiliary agent is 1:n-0, 2 to 1·n+0, corresponding to the number n of methine groups in the dye.
．． Contained at a ratio of 2.

More specifically, ■ In the case of a dye where n=o, the amount of the adjuvant is 0.8 to 1.2 mol, more preferably 0 to 1 mol of the dye.
．． The amount is 9 to 1.1 mol, more preferably 1 mol.

If this value is less than 0.8 or exceeds 1.2 mol, J-aggregates will not be formed, resulting in the inconvenience that the film will not be suitable for optical recording and will not be suitable for practical use. .

On the other hand, in the case of a dye with ■n=1, the amount of auxiliary agent is 1.8 to 2.2 mol, more preferably 1.9 mol, per 1 mol of the dye.
~2.1 mol, more preferably 2 mol.

If this value is less than 1.8 or exceeds 2.2 moles, J-
This causes the disadvantage that aggregates are not formed and the film is not suitable for optical recording and is not suitable for practical use.

The reason why the optimum mixing molar ratio of the film-forming auxiliary agent changes depending on the number of n in the methine group is presumed to be as follows. That is, the two 5s constituting the dye
They are roughly classified depending on whether or not there is a space between the carbon chains connecting the member rings (between the alkyl groups hanging from the 5-membered ring) into which a film-forming aid, such as stearic acid, can enter. By the way, n
When = 0, there is no space for stearic acid, and n = 1
In this case, this space is considered to exist.

Such a recording film of the present invention is formed by a so-called LB film forming method, and the method will be outlined below.

FIG. 1 is a perspective view showing an example of an LB film forming apparatus. In this figure, the LB film forming apparatus 20 is equipped with a water tank 21 for holding a lower layer liquid, and a dye used in the present invention and a film are formed on the lower layer liquid. A sample containing an adjuvant dissolved in a solvent is dropped.

In this case, the mixing ratio of the dye and film-forming aid should of course be within the above range.In the dropped sample, the solvent spreads on the lower layer liquid and evaporates, and the dye molecules are quickly released. spreads to the air-water interface,
A monomolecular film is formed by arranging the hydrophilic groups in the lower layer liquid and the hydrophobic groups out into the atmosphere.

Next, while moving the barrier 22 to the right in the figure, a predetermined membrane pressure is applied to the monolayer to fill the monolayer in an array.

In this case, the relationship between membrane pressure and absorbance changes, for example, as shown in FIG. 2. That is, as the film pressure of the pigment film increases, the absorbance peak shifts to longer wavelengths and the peak intensity also increases, and at a constant film pressure, the wavelength shift indicating the formation of J-aggregates is completed. . Therefore, the membrane pressure needs to be set higher than the pressure at which the wavelength shift is completed.

The film filled with such pressure that the wavelength shift is completed is transferred onto the substrate 10 by vertically moving the substrate 10 up and down.

Note that the lower layer liquid is generally pH-adjusted distilled water, and the solvent is a volatile solvent such as benzene or chloroform that is compatible with water.

Furthermore, the membrane pressure control of the monomolecular membrane is determined by the π-A curve obtained from the change in membrane pressure (π) on the air-water interface due to compression by the barrier 22 and the area (A) determined from the position of the barrier 22. This can be done based on the following. Furthermore, by simultaneously measuring the spectral characteristics of the dye, it is possible to confirm that a J-aggregate has been formed from the shift of the absorption peak.

Incidentally, the laser beam applied to the recording medium of the present invention is appropriately selected depending on the absorbance peak wavelength of the dye used.

[Effect]

The medium of the present invention is generally irradiated with recording light in a pulsed manner while rotating.

At this time, the J-aggregates in the irradiated portion of the recording film are destroyed, resulting in a decrease in absorbance.

Recording caused by a decrease in absorbance is performed by detecting the difference in the absorbance of the transmitted light of the readout light while the medium is rotated.

〔Example〕

Hereinafter, the present invention will be explained in further detail by showing examples of the present invention. The dye contained in the recording film has the above structural formula [
D-1] to [D-3], and the following [D
-4] dye was used.

Dye [D-4] The number of methine groups in the dye [D-1:] was set to n=2.

Other than that, the structure was the same as that of dye UD-1].

Furthermore, stearic acid was used as a film-forming auxiliary agent contained in the recording film. The film forming method followed the usual LB film forming conditions, and the mixing molar ratio of the film forming aid to the cyanine dye was varied at various ratios as shown in Table 1 below.

The film was characterized using a spectrophotometer, recording an absorbance curve as shown in FIG. 2, and evaluated using the following evaluation criteria.

◎...At a predetermined film pressure, a long wavelength shift was observed very clearly, and the material actually accumulated on the substrate showed absorption characteristics equivalent to those on the air-water interface.

O...At a predetermined film pressure, a long wavelength shift was clearly observed, and the material actually accumulated on the substrate showed absorption characteristics equivalent to those on the air-water interface.

×... Almost no long wavelength shift was observed,
Alternatively, although a slight shift was observed, when the material was actually accumulated on the substrate, it did not exhibit absorption characteristics equivalent to those on the air-water interface.

The results are shown in Table 1 below.

Table 1 21...Aquarium, 22... Barrier.

〔Effect of the invention〕

From the results in Table 1, the effects of the present invention are clear.

That is, the recording film of the optical recording medium contains a predetermined cyanine dye and a film-forming aid in a predetermined amount corresponding to the number n of methine groups in the dye.

Therefore, this recording film reliably forms J-aggregates, making it an extremely excellent recording film for optical recording.

Claims (1)

[Claims] In an optical recording medium having a recording film on a substrate, the recording film is a cyanine dye represented by the following general formula ▲ Numerical formula, chemical formula, table, etc. ▼ (wherein R_1 and R_2 are , represents an alkyl group, X represents a counter ion, A
represents one group selected from O, S, and C(CH_3)_2, and n represents an integer of 0 or 1) and a film-forming auxiliary agent, wherein the dye and the auxiliary agent in a molar ratio of 1:n-0, corresponding to the number n of methine groups in the dye.
．． An optical recording medium characterized in that the content is contained in a ratio of 2 to 1:n+0.2.