JP2778134B2 - Manufacturing method of optical recording medium - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for manufacturing a rewritable optical recording medium.

2. Description of the Related Art Conventionally, a photochromic compound is known as a material that causes a reversible color change by two types of light sources having different wavelengths. Spiropyran and fulgide are typical examples. Optical recording media based on binary storage utilizing these reversibility properties have been proposed and are being put to practical use.

Conventionally, one of the methods for producing these photochromic compounds has been described.
First, the LB method has been used. At this time, the photochromic compound was produced as a recording medium in a colorless state without photoisomerization.

Problems to be Solved by the Invention Generally, an optical recording medium comprising a photochromic compound is manufactured by a coating method such as spin coating. The Langmuir-Blodgett (LB) method is excellent for forming a uniform thin film of an organic substance. However, in order to form an LB film, it is first necessary to have hydrophobicity and hydrophilicity in one molecule. For example, a dye skeleton is used for the hydrophilic group, and a photochromic compound having a substituent such as a long-chain saturated hydrocarbon group is used for the hydrophobic group. However, even if it has sufficient hydrophobicity, it may be difficult to form a monomolecular film at the air-water interface because the hydrophilic-hydrophobic balance is poor as a molecule.

Therefore, an LB film of a desired photochromic compound may not be obtained. Generally, in that case, an LB film cannot be formed unless fatty acids and the like are mixed.

An object of the present invention is to solve such problems of the related art.

Means for Solving the Problems According to the present invention, after a spiropyran compound having a hydrophobic group of a photochromic compound is changed to a colored state, an optical recording medium is manufactured by an LB method using its own single component.

According to the above-described production method, by changing the photochromic compound into a colored state, the charge state in the molecule is changed and the hydrophilic-hydrophobic balance is improved, a monomolecular film is formed at the air-water interface, and a uniform LB film is formed. Can be manufactured.

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the drawings.

SP which is a photochromic compound having the following general formula
1, Each of SP16 was dissolved in benzene to 1 mmol / l. The subphase was controlled at a temperature of 18 ° C. using a phosphate buffer of pH7. Using this sample, an LB film was manufactured under the following conditions.

As a conventional example, the following LB film was prepared in a dark place. SP
1. After each SP16 was developed at the air-water interface, it was compressed at a speed of 10 mm / min. The surface pressure-area (π-A curve) at this time are shown in FIGS. It can be seen that the surface pressure of SP1 in FIG. Further, SP16 and b of FIG. 2 are increased surface pressure from molecular area is 20A ² or less, which indicates that the film is destroyed. Similar results were obtained by changing the sub-phase conditions such as pH, temperature, and compression rate. That is, not only SP1 having an unbalanced hydrophilic / hydrophobic property, but also SP16 having a balanced hydrophilic / hydrophobic property alone did not form a monomolecular film in a colorless state.

In the embodiment of the present invention, SP1 and SP16 were irradiated with ultraviolet rays to be colored before being developed, and then developed at the air-water interface. Further compression was performed by continuously irradiating ultraviolet rays. The π-A curves at this time are shown in FIGS. First
As shown in FIG. 7A, the pressure of SP1 did not increase at all, and no monomolecular film was formed, as in the case of performing in a dark place. Next,
As shown in b of FIG. 1, SP16 surface pressure from the area occupied by the 51A ² starts to rise. Therefore, when SP16 in which the hydrophilicity / hydrophobicity was balanced was brought into a colored state, a monomolecular film could be uniquely formed.

Next, accumulation was performed at a speed of 10 mm / min while maintaining the pressure of 25 mN / m on the monomolecular film on the air-water interface of SP16. Until the accumulation was completed, the monomolecular film was continuously irradiated with ultraviolet rays. At that time, the substrate used was quartz glass whose surface was treated with a toluene solution of trimethylchlorosilane. The LB film manufactured in this way had an average accumulation ratio of 1, and excellent accumulation was performed.

It was shown that a good LB film can be manufactured by irradiating ultraviolet rays to obtain a colored state.

For example, in the case of spiropyran, when it is in a colored state, the molecule is opened to become a zwitter ion, which increases hydrophilicity and forms a well-balanced monomolecular film.

Effect of the Invention As described above, according to the present invention, an LB film of a photochromic compound alone, which is a rewritable optical recording medium, can be obtained, and the optical recording medium can be manufactured by binary storage.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a graph showing π-A curves of SP1 and SP16 under ultraviolet irradiation, and FIG. 2 is a graph showing π-A curves of conventional SP1 and SP16 in a dark place.

────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Junichi Hibino 1006 Kazuma Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (58) Field surveyed (Int.Cl. ⁶ , DB name) G11B 7/26 G11B 7/24

Claims (2)

(57) [Claims] 1. A method for manufacturing an optical recording medium, comprising: changing a spiropyran compound having a hydrophobic group into a colored state; and manufacturing the spiropyran compound by an LB method. 2. A method for producing an optical recording medium, which comprises producing a spiropyran compound having a hydrophobic group represented by the following general formula into a colored state by irradiating ultraviolet rays, and then producing it by an LB method. _{R = -C 2 H 2n + 1} R '= H, OCH 3 or _{CH 2 COOC 21 H 43, (} n = 12~30)