JPS6127291A - Laser recording medium and production thereof - Google Patents

Abstract

PURPOSE:To ensure high sensitivity, high density and reversibility, by a construction wherein a recording layer is constituted of a built-up film of a J-associate of molecules of an organic coloring matter so that it has an absorption band in an oscillation wavelength range of laser. CONSTITUTION:The laser recording medium comprises a base, a reflective layer and the recording layer, in which the recording layer is constituted of a built-up film of the J-associate product of the molecules of an organic coloring matter and has an absorption band in the oscillation wavelength range of laser. The J-associate product is provided in the form of a built-up film by the Langmuir- Blodgett's method. First, a solution of a coloring matter of formula ( I ), wherein X is halogen, in an organic solvent (the dye may be mixed with arachic acid) is poured dropwise on a water surface in a water tank, and is spread to obtain a monomolecular film. Next, while compressing the monomolecular film under a fixed surface pressure, a substrate so disposed as to orthogonally traverse the water surface is repeatedly moved up and down a desired number of times, thereby transferring the film onto the substrate. Accordingly, the J-associate product in which the molecules of the coloring matter are oriented and arranged in a special aggregated condition can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a laser recording medium and a method for manufacturing the same.

BACKGROUND TECHNOLOGY AND PROBLEMS A large number of laser beam recording media using organic dyes have been prototyped in the past, but the recording principle of these recording media is based on the change in shape of the recording medium due to the heat generated when the dye absorbs the laser beam. Therefore, in practical use, it is difficult to directly hermetically protect the recording layer from both sides, and measures such as the adoption of an air sandwich structure are required, resulting in a recording medium with a complicated structure. In addition, in these conventional recording media, consideration must be given to controlling the change in the shape of the recording location to a spot with a uniform shape and minute size. For this reason, (1) the recording principle of these recording media itself is an obstacle to high-density recording, which has been strongly desired recently. moreover,
A minimum amount of energy for melting and vaporization is required to cause the above-mentioned shape change of the medium, and this shape change is accompanied by the separation of dye molecules from the recording focus, and is therefore not reversible.

When the concentration of organic dye molecules, such as cyanine dyes, increases in an aqueous solution, in addition to the absorption band of a single dye molecule, the dimer absorption band and the multimolecular association absorption band on the shorter wavelength side, The absorption intensity is large on the longer wavelength side than the molecular absorption band,
It has an absorption band with a very narrow half-width. This absorption band is called a J-absorption band, and is known to belong to an aggregated state of dyes called a J-aggregate.

The present inventors discovered that this J-aggregate dissociates upon heating,
Noting that the absorption spectrum changes significantly before and after dissociation, the present invention was completed by utilizing a cumulative film of J-aggregates as a recording layer.

OBJECTS OF THE INVENTION The present invention addresses the above points and provides a laser beam recording medium using an organic dye and a method for manufacturing the same, which has characteristics of high sensitivity, high density, and reversibility.

Summary of the Invention A laser recording medium according to the present invention includes a substrate, a reflective layer, and a recording layer, in which the recording layer is a cumulative film of J-aggregates of organic dye molecules, It is characterized by having an absorption band in the wavelength range.

Further, the method for manufacturing the laser recording medium according to the present invention includes:
The J-aggregate is formed as a cumulative film by the Langmuir-Blodgett method (hereinafter referred to as LB method).

The lamination order of each layer in the laser recording medium of the present invention is (
Either a) substrate-reflection layer-recording layer or (b) substrate-recording layer-fouling layer may be used. Depending on the lamination order in (b) above, recording can be performed on a recording layer that is hermetically protected from both sides.

As the organic dye molecule, for example, the following formula (I) (wherein,
X represents a halogen).

The formation of the J-aggregate cumulative film by the LB method can be performed as follows. First, the dye of general formula (1) dissolved in an organic solvent (which may be mixed with other film-forming molecules, such as arachidic acid) is dropped onto the water surface of a water tank and spread to obtain a monomolecular film. Next, while compressing this monomolecular film under a constant pressure, it is transferred onto a substrate that vertically crosses the water surface by repeatedly moving it up and down a desired number of times. In this way, the dye molecules are oriented and arranged to form a J-aggregate in a special state of assembly. In this J-aggregate of dye molecules, the light absorption spectrum changes greatly as a result of minute changes in the state of assembly caused by heat. The laser recording medium of the present invention uses the recording principle of minute changes in the aggregated state of dye molecules caused by laser light.

As can be understood from the recording principle, the recording layer in the laser recording medium of the present invention is reversible and rewritable in principle since the dye does not disperse from the recording focus.

Embodiments of the present invention will be described below with reference to the drawings.

Example 1 ′ FIG. 1 shows a laser recording medium 1 of this embodiment.

This recording medium 1 includes a glass substrate 2, an aluminum laminate 1, a reflective film 3 (about 2,000 layers thick), and a recording layer 4 (about 1 layer thick).
．． 600 people) were stacked in the order shown. Recording layer 4
is a cyanine dye represented by the following formula (II) and arachidic acid (C1qH3qc
The cyanine dye is present as a J-aggregate in this film. This recording medium 1 can be manufactured as follows.

The cyanine dye of formula (II) and arachidic acid were dissolved in dichloromethane/methanol (4:1) at a molar ratio of 1=4, and a solution was prepared such that the concentration of arachidic acid was 1 mg/mβ. This solution was dropped onto the surface of distilled water at 16°C until the occupied cross-sectional area of arachidic acid became 25 yne/molecule per molecule to develop a monomolecular film, and then the partition on the water surface was moved to increase the surface pressure to 106 yne/2. Compress until cm, 15
After standing for a minute, it was further compressed to 40 dyne/cm. This monomolecular film is coated with R3 method and has a thickness of approximately 2,000 mm.
0 People's Aluminum Reflective Film 3 Inquiry Saw Crow Substrate 2
A recording layer 4 with a thickness of about 1,600 A was formed by accumulating 50 layers, and the recording medium L was dried and irradiated with light from the side of the recording layer 4 of the thus prepared recording medium 1 to obtain a reflection/absorption spectrum. As a result of the measurement, curve A shown in FIG. 2 was obtained. On the other hand, the absorption spectrum of a single molecule of the cyanine dye of formula (II) (
(measured with a 10-'M methanol solution) was as shown in curve B of FIG. By comparing curve A with curve B, it can be confirmed that the absorption band at 785 nm of curve A belongs to the aggregation state of the dye called J-aggregate, and the cyanine dye in the recording layer 4 is J-aggregate. It can be seen that it exists as an aggregate. In this recording layer 4, Fludge J,
When the material was instantaneously heated by irradiation with light, the aggregation state of the J-aggregates was disturbed, so that the absorption band at 785 nm disappeared as shown by the broken line C in FIG.

In Figure 3, a semiconductor laser beam with a wavelength of 785 nm is applied to the recording layer 4 with a diameter of 1.6 μm, and a power of 5 mW (on the recording layer 4).
The graph shows the change in reflectance obtained by pulse irradiation.

This reflectance change was determined by weakening the output of the laser used for pulse irradiation (writing) and measuring the reflected light intensity before and after pulse irradiation. As a result, the maximum laser output (7,5mW
), a 15% reflectance change (
10% → 25%) was obtained. This is about 0.03 J
/cm2, which is almost comparable to the sensitivity required for a real-time video signal recording medium using a semiconductor laser.

Real h1! ! Example 2 In this example, as shown in FIG. 4, a recording layer 4 (with a thickness of approximately 1.60 mm
A laser recording medium 5 was obtained by forming an aluminum reflective film (about 1.000 mm thick) on the second layer.

Therefore, the recording layer 4 is protected from both sides.

This recording medium 5 was irradiated with semiconductor laser light in the same manner as in Example 1 except that it was irradiated from the glass substrate 2 side, and the reflux rate change 1 curve shown in the graph of FIG. I got it. As described above, according to the configuration of the recording medium 5 of this embodiment, recording can be performed on the recording layer 4 which is hermetically protected from both sides.

In each of the above embodiments, a transparent layer, for example, an arachidic acid cumulative film, may be provided between the reflective layer and the recording layer to reduce the cumulative number of recording layers.

Effects of the Invention As described above, in the recording medium of the present invention, since the recording layer is a J-aggregate of monochromatic dye molecules, the following effects can be obtained by the present invention.

(1), the change in the assembly state of the J-aggregate is caused by several dye molecules ~
Since the recording occurs in units of several tens, the unit of the medium responsible for recording is extremely small, and recording spots with uniform shapes and minute dimensions can be obtained, thus enabling high-density recording.

(2) Since there is no major change in the shape of the recording medium, it is possible to protect the recording layer from both sides, and the structure of the recording medium is simple in practical use.

(3) The recording principle utilizes changes in the absorption spectrum due to minute changes in the aggregated state of dye molecules;
The energy required for the recording process is small, and therefore high recording sensitivity can be obtained.

(4) Furthermore, since the recording principle does not involve dispersion of the dye from the recording focus, it can be a reversible and rewritable recording medium.

Furthermore, according to the method of the present invention, since the J-aggregates forming the recording layer are produced as a cumulative film by the LB method, the film 1ν of the recording layer can be controlled with high precision.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of the first embodiment of the laser recording medium of the present invention, FIG. 2 is a graph showing the absorption spectrum, FIG. 3 is a graph showing reflectance changes in the first embodiment, and FIG. A cross-sectional view of the second embodiment of the invention and FIG. 5 are graphs showing reflectance changes in the second embodiment. In addition, in the symbols used in the drawings, 1-...-----11--Recording medium 2-
-----------1--Substrate 3----1-----・---1--Reflecting film 4--
---------One recording layer 5------------Recording medium 6--
---------1-----It is a reflective film. Figure 1 Figure 2

Claims (1)

[Scope of Claims] 1. A laser recording medium having a substrate, a reflective layer, and a recording layer, wherein the recording layer is a cumulative film of J-aggregates of organic dye molecules, and is in the oscillation wavelength range of the laser. A laser recording medium characterized by having an absorption band. 2. The laser recording medium according to claim 1, wherein the substrate, the reflective layer, and the recording layer are laminated in the stated order. 3. The laser recording medium according to claim 1, wherein the substrate, the recording layer, and the anti-fouling layer are laminated in the stated order. 4. A method for manufacturing a laser recording medium having a substrate, a reflective layer, and a recording layer, the recording layer being a cumulative film of J-aggregates of organic dye molecules, and having an absorption band in the laser oscillation wavelength range. A method for manufacturing a laser recording medium, characterized in that the cumulative film of J-aggregates is formed by a Langmuir-Blodgett method. 5. The method according to claim 4, wherein the substrate, the reflective layer, and the recording layer are laminated in the stated order. 6. The method according to claim 4, wherein the substrate, recording layer, and reflective layer are laminated in the stated order.