JPH0470619B2 - - 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 reversibilities (published in Sho-
61-205187) There are no examples of this being 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, and the recording density is low. You can only get something with a low value.

Means for Solving the Problems 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 including a recording layer is formed.

(However, R ₁ = −CH ₂ OCOC _o H _2o+1 , R ₂ = −C _n
H _2n+1 , n and m are natural numbers) (Function) By forming a recording layer using the above compounds, 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 Example 1 Spiropyran (hereinafter referred to as
(abbreviated as SP1822) was used.

Prepare a solution of SP1822 in benzene to a concentration of 1mM, and apply it under normal conditions (subphase: PH7/phosphate buffer, temperature 18℃,
Compression speed: 20mm/min, cumulative pressure: 20mN/m)
By the LB method, it was deposited on a quartz substrate to form a thin film.
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. Further, the number of layers was one, and the film thickness was about 25 Å. The recording layer composed of the aggregates thus produced is designated as 1 . 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) Accumulated by LB method.

Furthermore, 10 layers were accumulated on top of this using sample solutions in which SP1822 and stearic acid were dissolved in benzene at concentrations of 0.1 mM and 1 mM, respectively. The conditions for accumulation are the same as for the accumulation of a single film of stearic acid. The recording layer made of the monomer thus produced is referred to as 2 .

Laser light (λ=
340nm), the fluorescence spectrum became as shown in the figure. This is a state in which information has been erased, and recording layers 1 and 2 are formed with aggregates (colored bodies) and monomers (colored bodies) of SP1822, respectively. By irradiating this with a certain amount of laser light (λ = 560 nm), the absorption 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=
618nm), fluorescence with wavelengths longer than 600nm was eliminated. (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 in the recording layers 1 and 2 was erased again by irradiation with laser light (λ=340 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 are different.

Example 2 Under the same conditions as Example 1, one layer of a mixed film of SP1822/octadecane=1/2 was accumulated on a quartz substrate by the LB method. A recording layer 1 is made of the aggregate thus produced. 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: 20 mm/min, cumulative pressure: 30 mN/m) were accumulated by the LB method. Finally, 10 layers of SP1822/octadecyl alcohol=1/10 mixed film were accumulated by the LB method under the same conditions as in Example 1. Recording layers 1 and 2 made of monomers thus obtained exhibited writing and erasing characteristics similar to those of Example 1.

Example 3 Using SP1822 dissolved in toluene at a concentration of 10 mM, a recording layer was formed by spin coating on one side of quartz glass treated in the same manner as in Example 1 at 600 rpm for 60 seconds. The recording layer composed of the aggregates thus produced is designated as 1 . Furthermore, a thin film of SP1822/stearic acid=1/10 was formed on the other remaining surface by spin coating at 600 rpm for 60 seconds. The recording layer made of the monomer thus produced is referred to as 2 . The solution is SP1822,
Stearic acid was dissolved in toluene to a concentration of 5mM and 50mM, respectively.

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

Effects of the Invention The present invention makes it possible to provide a rewritable optical recording medium that can record two or more states simply by using one photochromic compound, and its ripple effects are significant.

[Brief explanation of the drawing]

The figure is a fluorescence spectrum diagram of a writing state and an erasing state in an 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 ₁ = −CH ₂ OCOC _o H _2o+1 , R ₂ = −C _n
H _2n+1 , n and m are natural numbers) 2 The monomer layer is a mixture 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 fatty acid metal salts. The optical recording medium according to claim 1, which is a film. 3. The optical system according to claim 1, wherein the aggregate layer is a single film of the photochromic compound of general formula 1 or a mixed film of the photochromic compound of general formula 1 and a long-chain hydrocarbon. recoding media. 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 comprising a recording layer having a monomer and an aggregate of a photochromic compound represented by the following general formula 1, the recorded state of the monomer and aggregate of a photochromic compound in the recording layer is determined by fluorescence. A recording state detection method characterized by detecting. (However, R ₁ = −CH ₂ OCOC _o H _2o+1 , R ₂ = −C _n
H _2n+1 , n and m are natural numbers)