JPH0869083A - Optical recording medium and its production - Google Patents

Abstract

PURPOSE: To obtain an optical recording medium having high sensitivity for laser light and durability for recording and reproducing which does not cause scattering of laser light due to crystallization of the medium in air, by forming a thin film of a photochromic compd. comprising a coloring material as the recording layer on a substrate. CONSTITUTION: This optical recording medium 12 has a thin film of diarylethene-based photochromic compd. as a recording layer 8 on a substrate 7. The photochromic compd. consists of a coloring material. The optical recording medium 12 is produced by separating a coloring material from a diarylethene-based photochromic compd. containing at least the coloring material and a decolorizatio material, forming a thin film of the obtd. coloring material as a recording layer 8 by vacuum vapor deposition on the substrate 7, and then forming a reflection layer 9, protective layers 10, 11 in this order. The coloring material is obtd., for example, by irradiating a decolorization material with light of specified wavelength such as 360nm to obtain a mixture of a coloring material and a decolorization material, and then separating only the coloring material from the mixture.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to an optical recording medium using a photochromic compound.

[0002]

2. Description of the Related Art In recent years, as a recording material, a compound having a photochromic property that reversibly changes its phase upon irradiation with light has been proposed. For example, compounds such as benzospiropyrans, naphthoxazines, fulgides, diazo compounds and diarylethenes have been proposed as those photochromic compounds. Among them, compounds such as diarylethenes are very excellent in thermal stability in both colored state and decolored state, and have high durability against repeated coloring and decoloring, and are suitable for reversible optical recording materials. It is a good material. In order to use a photochromic compound as a recording medium, a method of forming a thin film on a substrate by a method such as a spin coating method, a casting method and a Langmuir-Blodgett (LB) method has been proposed.

[0003]

However, in these methods, it is difficult to form a recording film having a high concentration of a photochromic compound, and even if a recording film having a high concentration of a photochromic compound is formed, it is exposed to the air. However, there is a drawback that the laser light is scattered due to the crystal grains.

The present invention has been made in view of such circumstances, and an object thereof is to provide an excellent optical recording medium having a high concentration and a thin film of a diarylethene compound in which crystal grains are not generated.

[0005]

The present invention provides an optical recording medium having at least a recording layer which is a thin film of a diarylethene photochromic compound provided on a substrate, wherein the photochromic compound comprises a colored body. A recording medium is provided.

Further, according to the present invention, a recording layer is formed by separating a colored body from a diarylethene-based photochromic compound containing at least a colored body and a decolorized body and forming a thin film of the obtained colored body on a substrate by vacuum vapor deposition. And a method for producing an optical recording medium including the step of separating the colored body from a diarylethene-based photochromic compound containing at least a colored body and a decolorized body, and forming a thin film of the obtained colored body on a substrate by vacuum deposition. To form a recording layer,
Then, a method of manufacturing an optical recording medium is provided, which includes a step of forming a reflective layer and a protective layer in that order.

The colored body of the diarylethene-based photochromic compound used in the present invention is such that only the colored body is selected from the mixture of the obtained colored body and the decolorized body by irradiating the decolorized body with light having a specific wavelength such as 360 nm. It can be manufactured by separating. As the separation method, liquid chromatography, which is a method of separating and fractionating by utilizing the difference in molecular adsorption to the column due to the difference in chemical structure between the colored body and the decolorized body, is preferably used. Further, in order to prevent the color from disappearing during the separation operation, light having a wavelength that causes ring opening such as light having a wavelength of 360 nm described above is shielded, that is, by using a UV cut filter, a separation device (liquid It is important to shield the separated portion of the chromatograph so that 360 nm light does not reach. Since the colored body of the diarylethene compound does not return to the decolorized body by heat, only the colored body can be easily obtained by the above operation.

The substrate of the present invention may be any substrate that transmits light used for writing, reading or erasing, and examples thereof include a glass plate, a plastic substrate such as polycarbonate, PMMA, polystyrene and the like.

In the present invention, the recording medium is formed by the vacuum deposition method.
To prepare, first diarylethene conversion on the above substrate
The compound colored body is vacuum-deposited. Diarylethene compound
The thickness of the thin film can be selected appropriately within the range where the signal can be read.
However, it is usually 0.1 μm to 5 μm. Furthermore
On the diarylethene thin film while maintaining the vacuum state.
A reflective film of Al, AlCr, etc. (Normal thickness is 0.01μ
m-1 μm) or Si ₃N_Four, SiO₂Form a protective film such as
Then, even if it is exposed to the air, it does not crystallize and is transparent.
A recording medium can be obtained.

The vacuum vapor deposition apparatus preferably has a structure capable of shielding light so that the colored body does not return to the decolored body during vapor deposition. After the diarylethene compound is vapor deposited, a reflective film is formed without returning to normal pressure. Is more preferable. Also,
The vapor deposition temperature can be appropriately selected within a range in which the diarylethene compound does not cause thermal decomposition.

Examples of the diarylethene compound used in the present invention include those represented by the following general formula I.

[0012]

[Chemical 4] In the formula, Ar ¹ and Ar ² are

[0013]

[Chemical 5] Or

[0014]

[Chemical 6]And R¹Is an alkyl group, an acyl group or an aryl group
And R²And R⁷Is an alkyl group, perfluoroal
R is a kill group or an alkoxy group,³~ R⁶, R ⁸And
And R⁹Is an alkyl group, an acyl group, an alkoxy group, a dial
It represents a kylamino group, an aryl group or a cyano group.

The colored body of the diarylethene-based photochromic compound used in the present invention is prepared by irradiating the decolored material with light having a specific wavelength and separating only the colored body from the obtained mixture of the colored body and the decolorized material. , Can be manufactured.

As a separation method, a fractional crystallization method or liquid chromatography is preferably used. In addition, it is important to block light of a wavelength that causes ring opening so that the color does not disappear during the separation operation.

Since the colored body of the diarylethene compound does not return to the decolorized body by heat, only the colored body can be easily obtained by the above operation.

Thus, by separating only the colored body from the mixture of the colored body of the diarylethene-based photochromic compound and the decolorized body and removing the decolorized body, only the colored body having uniform properties is used as the recording layer. Is possible, and there is an effect that crystallization of the recording layer due to aging does not occur.

[0019]

【Example】

Example 1 The production of an example of the recording medium of the present invention will be described with reference to FIG.

As the diarylethene compound, 1,2-
Bis (2-methyl-3-benzothienyl) -3,3
4,4,5,5-hexafluorocyclopentene was used.

This toluene solution of the diarylethene compound was irradiated with 20 W of ultraviolet light, and the obtained mixture of the colored substance and the decolorized substance was separated by high performance liquid chromatography with a mixed eluent using a silica gel column in a dark room. The colored body was collected.

Next, the colored body of the diarylethene compound was placed in the heating port of the vacuum vapor deposition machine, and the degree of vacuum was 10 ^-5 To.
After the temperature was set to rr, the heating port containing the diarylethene compound was heated and vapor-deposited on the glass substrate 7. The thin film of the recording layer 8 made of the compound was 0.6 μm.

Further, a thickness of 0.01 μm is formed on the recording layer 8.
m, an Al layer is provided as a reflective film 9, an inorganic dielectric layer is provided as a protective film 10 on the reflective film 9 with a thickness of 0.05 μm, and an ultraviolet curable resin protective layer 11 is further formed thereon. The optical recording medium 12 was prepared by providing the optical recording medium 12 with a thickness of 5 μm.

After this, the optical recording medium was taken out and allowed to stand at room temperature for 3 months, but white turbidity due to crystallization of the diarylethene compound did not occur.

(Example 2) 1- (1,2-dimethyl-3-indolyl) -2-as a diarylethene compound
(2-Methyl-3-benzothienyl) -3,3,4
An optical recording medium was produced in the same manner as in Example 1 except that 4,5,5-hexafluorocyclopentene was used.

The thickness of the diarylethene compound thin film is
It was 0.8 μm.

Even when this optical recording medium was allowed to stand at room temperature for 3 months, white turbidity due to crystallization did not occur.

Example 3 As a diarylethene compound, 1- (5-methoxy-1,2-dimethyl-3-indolyl) -2- (5-cyano-2,4-dimethyl-3-) was used.
An optical recording medium was produced in the same manner as in Example 1 except that thienyl) -3,3,4,4,5,5-hexafluorocyclopentene was used and 10 W of black light was used as the colored light.

The thickness of the diarylethene compound thin film is 0.
It was 7 μm.

When this optical recording medium was allowed to stand at room temperature for 3 months, white turbidity due to crystallization did not occur.

Comparative Example 1 The same as Example 1 except that the same compound as in Example 1 was used as the diarylethene compound, without being irradiated with ultraviolet rays and in that the colored body and the decolorized body were not separated. Then, an optical recording medium was produced.

(Comparative Example 2) The same as Example 1 except that the same compound as in Example 2 was used as the diarylethene compound, without being irradiated with ultraviolet rays, and the colored body and the decolorized body were not separated. Then, an optical recording medium was produced.

(Comparative Example 3) As in Example 1 except that the same compound as in Example 3 was used as the diarylethene compound without irradiation with black light and the colored body and the decolorized body were not separated. Similarly, an optical recording medium was produced.

An aluminum reflective layer was formed on the thin film of the diarylethene compound of Examples 1, 2 and 3 above.
A filter (H
OYA, U-330) equipped with a 100W ultra-high pressure mercury lamp (HBO100W / cm ² manufactured by Osram) was irradiated with ultraviolet rays, and its reflection spectrum was measured.
2 and 3. As shown in these figures, the spectrum changed from the solid line spectrum to the broken line spectrum.

Next, when visible light was radiated using a filter for blocking light of 400 nm or less, Examples 1 to 3 were obtained.
Then, the spectrum returned to the original solid line, and even after the alternate irradiation of ultraviolet light and visible light was repeated 1000 times, it did not change from the initial spectrum change.

On the other hand, when the optical recording media of Comparative Examples 1 to 3 were left to stand at room temperature for 3 months, white turbidity was generated due to crystallization of the recording layer and recording became impossible.

[0037]

As described above, according to the present invention, it is possible to obtain an optical recording medium which has high sensitivity to laser light and which does not cause scattering of laser light due to crystallization in the atmosphere and has high recording and reproducing durability. it can.

[Brief description of drawings]

FIG. 1 is a schematic sectional view showing the structure of an optical recording medium of the present invention.

FIG. 2 is a diagram showing a spectrum change of the optical recording medium of Example 1.

FIG. 3 is a diagram showing a spectrum change of an optical recording medium of Example 2.

FIG. 4 is a diagram showing a spectrum change of an optical recording medium of Example 3.

[Explanation of symbols]

 1, 3 and 5 spectrum of decolored state 2, 4 and 6 spectrum of colored state 7 substrate 8 recording layer 9 reflective film 10 inorganic dielectric layer 11 UV-curable resin protective layer 12 optical recording medium

Claims (5)

[Claims] 1. An optical recording medium having at least a recording layer, which is a thin film of a diarylethene-based photochromic compound, provided on a substrate, wherein the photochromic compound comprises a colored body. 2. A photochromic diarylethene system
The compound is a compound represented by the following general formula I.
Optical recording medium mounted. [Chemical 1](In the above formula, Ar¹And Ar²IsOr [Chemical 3]And R¹Is an alkyl group, an acyl group or an aryl group
And R²And R⁷Is an alkyl group, perfluoroal
R is a kill group or an alkoxy group,³~ R⁶, R ⁸And
And R⁹Is an alkyl group, an acyl group, an alkoxy group, a dial
It represents a kylamino group, an aryl group or a cyano group. ) 3. A step of separating a colored body from a diarylethene photochromic compound containing at least a colored body and a decolorized body, and forming a thin film of the obtained colored body on a substrate by vacuum vapor deposition to form a recording layer. A method for manufacturing an optical recording medium including the following. 4. A step of separating a colored body from a diarylethene-based photochromic compound containing at least a colored body and a decolorized body, and forming a thin film of the obtained colored body on a substrate by vacuum vapor deposition to form a recording layer. And then forming a reflective layer and a protective layer in that order, a method of manufacturing an optical recording medium. 5. The method for producing an optical recording medium according to claim 3, wherein the separation of the colored body is performed by liquid chromatography while blocking light having a wavelength that changes the colored body to an erasable body.