JPH0470620B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a rewritable optical recording medium with high recording density.

BACKGROUND ART Conventionally, photochromic materials have been known as materials that produce reversible color changes using two types of light sources with different wavelengths. Spiropyran is a typical example. Optical recording media based on binary storage have been proposed by utilizing these reversible properties (Japanese Patent Application Laid-Open No. 1983-1992).
-205187 Publication) No examples have been found that have been put into practical use.

Problems to be Solved by the Invention When applying the reversible reaction between colorless and colored spiropyran to optical storage media, only one state can be recorded as long as one type of spiropyran is used. Only low density products can be obtained.

Means for Solving the Problem At least two layers comprising a monomer layer having a monomer of a photochromic compound represented by the following general formula and an aggregate layer having an aggregate of a photochromic compound represented by the following general formula. An optical recording medium having a recording layer of is formed.

(However, R is an alkyl chain with C=1 to 31.) Function By forming a recording layer using the above compound, monomers with different absorption spectra or fluorescence spectra can be formed by using only one type of photochromic compound. It is possible to provide a high-density rewritable optical recording medium that can record two or more states consisting of a combination of aggregates.

Examples The optical recording medium of the present invention uses a monomer and an aggregate of a photochromic compound represented by the above general formula, where R is a hydrocarbon up to C=31 whose raw material is easily available industrially. . Preferably C=13
to C=23, with a good balance of hydrophilicity and hydrophobicity, and can easily form LB films.

However, the monomer layer containing the monomer may be a single film of the photochromic compound described in claim 1, or the above-mentioned photochromic compound, a long-chain fatty acid metal salt, or one of the long-chain hydrocarbons. Formed by a mixed film of more than one species.

Furthermore, the aggregate layer having aggregates is formed of a mixed film of the photochromic compound described in claim 1 and one or more substances selected from long-chain fatty acids, long-chain alcohols, and long-chain esters. do.

Further, a separation layer may be provided between the recording layers.

The recording state is detected by absorption and fluorescence.

Example 1 Spiropyran (hereinafter referred to as
SP1801) was used.

SP1801 and stearic acid together in benzene at 1mM
A sample solution was prepared by dissolving the sample at a concentration of . This was carried out under normal conditions (subphase: PH7/phosphoric acid buffer, temperature 18℃, compression speed: 20mm/min, cumulative pressure:
A thin film was formed by accumulating it on a quartz substrate using the LB method at 20 mN/m. The quartz substrate was immersed in a 10% toluene solution of trimethylchlorosilane for 10 minutes and then washed with trichloroethane to make it hydrophobic in advance. The film structure at this time was accumulated in a Z-shape in which all the hydrophilic groups were directed toward the substrate. Further, the number of layers was two, and the film thickness was about 50 Å. The recording layer of the aggregate layer thus produced is designated as 1.

Furthermore, SP1801 dissolved in benzene to a concentration of 1mM was used on top of this.
Three layers were accumulated using the LB method. Conditions such as subphase, water temperature, compression speed, and cumulative pressure during accumulation are as follows:
It is the same as in the case of the accumulation of a mixed film of SP1801 and stearic acid. The recording layer of the monomer layer produced in this manner is referred to as 2.

Laser light (λ=
360nm), the fluorescence spectrum became as shown in the figure. This is a state in which information has been erased, and the recording layers 1 and 2 are formed with aggregates (colored bodies) and monomers (colored bodies) of SP1801, respectively. By irradiating this with a certain amount of laser light (λ = 600 nm), the fluorescence spectrum became as shown in the figure. This is a state in which one piece of information is written in the recording layer 1, and monomers (colorless bodies) and aggregates (colored bodies) are formed in the recording medium.
In addition, the output was increased 5 times and the laser beam (λ=
600nm), the fluorescence with wavelengths longer than 600nm disappeared. (In the diagram) This is recording layer 2
Information is written on the recording medium, and only monomers (colorless bodies) are formed in the recording medium. Here, the information recorded on the recording layers 1 and 2 was erased again by irradiation with laser light (λ=360 nm).

Note that even if absorption spectra were used in addition to fluorescence spectra, the above erasing and writing states could be detected, since the absorption spectra of monomers and aggregates were different.

Example 2 Two layers of a mixed film of SP1801/stearic acid=1/1 were deposited on a quartz substrate by the LB method under the same conditions as in Example 1. The recording layer of the aggregate layer thus produced is designated as 3.

On top of this, 8 layers of barium stearate (developing substance: stearic acid 1mM benzene solution, subphase: PH8.6/BaCl ₂ , KHCO ₃ , temperature 18°C, compression speed: 20mm/min, cumulative pressure: 30mN/m) This was deposited by the LB method, and on top of this, three layers of SP1801/octadecane=1/3 mixed film were deposited by the LB method under the same conditions as in Example 1. The recording layer of the monomer layer produced in this way is referred to as 4.

The obtained recording layers 3 and 4 exhibited writing and erasing characteristics similar to those of Example 1.

Example 3 Both SP1801 and stearyl alcohol are 30mM
One side of quartz glass treated in the same manner as in Example 1 was prepared by dissolving it in toluene at a concentration of
A recording layer was formed by spin coating at 600 rpm for 60 seconds. The recording layer of the aggregate layer thus produced is designated as 5.

Furthermore, on the other side that remains,
By spin coating at 600 rpm for 60 seconds,
A thin film of SP1801 was formed. The recording layer of the monomer layer thus produced is designated as 6.

A 3mM toluene solution of SP1801 was used as the solution.

The recording layer obtained in the above manner was as follows: Example 1
It showed similar write and erase characteristics.

Effects of the Invention According to the present invention, it is possible to provide a rewritable optical recording medium that can record two or more states simply by using one photochromic compound.

[Brief explanation of the drawing]

The figure is a graph showing fluorescence spectra in a writing state and an erasing state in one embodiment of the present invention.

Claims (1)

[Scope of Claims] 1. A monomer layer containing a monomer of a photochromic compound represented by the following general formula 1, and a monomer layer having a monomer of a photochromic compound represented by the following general formula 1.
An optical recording medium comprising at least two recording layers including an aggregate layer having an aggregate of a photochromic compound represented by: (However, R is an alkyl chain with C=1 to 31.) 2. The monomer layer is a single film of the photochromic compound of general formula 1, or one or more substances selected from long-chain fatty acid metal salts and long-chain hydrocarbons. The optical recording medium according to claim 1, wherein the optical recording medium is a mixed film of a photochromic compound of general formula 1. 3. Claim 1, wherein the aggregate layer is a mixed film of the photochromic compound of general formula 1 and one or more substances selected from long-chain fatty acids, long-chain alcohols, and long-chain esters. Optical recording medium described in Section 1. 4. The optical recording medium according to claim 1, wherein the recording layer is formed as an LB film. 5 In an optical recording medium equipped with a recording layer containing monomers and aggregates of a photochromic compound represented by the following general formula 1, the recording state of the monomer and aggregates of a recording photochromic compound can be determined by absorption or fluorescence. A recording state detection method characterized by detecting a recording state. (However, R is an alkyl chain with C=1 to 31)