JPH06116556A - Phenolic light stabilizer for cyanine dye and optical recording medium containing the same light stabilizer - Google Patents

Abstract

PURPOSE:To obtain a simply handleable phenolic light stabilizer, having a specific structure, capable of providing a light recording medium excellent in light fastness due to its remarkable excellence in light stabilizing effects on a cyanine dye and having high safety. CONSTITUTION:The light stabilizer is expressed by formula I (R is alkyl, cycloalkyl alkoxyalkyl or phenyl or aralkyl which may be substituted). For example, a compound of formula II can be used as the light stabilizer. This light stabilizer is used in an amount of usually 0.01-3 molar ratio to the cyanine dye. Furthermore, the light stabilizer is applied to an optical recording medium by dissolving, e.g. the light stabilizer together with the cyanine dye in a solvent such as ethanol, then coating a substrate of the recording medium with the resultant solution and forming a thin film.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a light stabilizer for a cyanine dye and an optical recording medium containing the light stabilizer.

[0002]

2. Description of the Related Art Optical recording media, so-called optical discs, using a thin film of a cyanine dye as a recording layer have been put into practical use. The cyanine dye used here has poor light stability by itself, and it is necessary to add a light stabilizer for use.

A method using a metal complex such as a nickel compound having a thio ligand as a light stabilizer is disclosed in JP-A-59 / 59.
-2119852, JP-A-62-193891, JP-A-62-207688, JP-A-63-19293,
It is shown in JP-A-63-199248. This method utilizes a mechanism that deactivates highly reactive singlet oxygen generated by light and returns it to triplet oxygen, but the problem is that decomposition of the cyanine dye proceeds considerably when exposed to light for a long time. Have a point.

Further, a method using a nitroso compound as another light stabilizer is shown in JP-A-2-300287, JP-A-2-300288 and JP-A-2-300289. However, many of these nitroso compounds have a problem that they are highly toxic or photolysates are toxic themselves, and it is necessary to take safety measures for the human body when using nitroso compounds. Etc. have unfavorable properties.

Further, a method using a compound having a trinitrophenylhydrazyl free radical as a light stabilizer is
It is shown in JP-A-2-304055. However, a compound having a trinitrophenylhydrazyl radical is
It is explosive and is a very problematic handling.

[0006]

An object of the present invention is to improve the photostability of a photostabilizer which solves these problems, that is, a cyanine dye, and is easy to handle and highly safe photostabilization. To provide an agent. Another object of the present invention is to provide an optical recording medium having excellent light resistance.

[0007]

The inventors of the present invention have conducted extensive studies to solve the above-mentioned problems, and as a result, have shown that the formula (1) (formula 2)

[0008]

[Chemical 2]

[In the formula, R represents an alkyl group, a cycloalkyl group, an alkoxyalkyl group, an optionally substituted phenyl group, or an aralkyl group. The present invention has been completed by finding that the phenol derivative represented by the following formula has properties that the light stability of the cyanine dye is extremely improved, and that the handling is easy and the safety is high. That is, the present invention is represented by the general formula (1)

[0010]

[Chemical 3]

[In the formula, R represents an alkyl group, a cycloalkyl group, an alkoxyalkyl group, an optionally substituted phenyl group, or an aralkyl group. ] A light stabilizer for a phenolic cyanine dye represented by the following, and an optical recording medium containing the light stabilizer.

The present invention will be described in detail below. Specific examples of R in the general formula (1) (Formula 3) of the present invention include a methyl group, an ethyl group, an n-propyl group, an i-propyl group,
n-butyl group, n-pentyl group, n-hexyl group, n-
Alkyl group such as octyl group, n-decyl group, n-dodecyl group, n-octadecyl group, cyclobutyl group, cyclopentyl group, cyclohexyl group, cycloalkyl group such as cyclooctyl group, methoxyethyl group, ethoxyethyl group, methoxypropyl Group, ethoxypropyl group, alkoxyalkyl group such as n-octyloxyethyl group, benzyl group, 2-phenylethyl group, 3-phenylpropyl group, aralkyl group such as 2-phenylpropyl group, phenyl group, 2-methylphenyl And optionally substituted phenyl groups such as 4-methylphenyl group.

The first specific representative example of the light stabilizer of the present invention
It shows in a table (Tables 1-2). These light-stabilizing compounds of cyanine dyes can be used alone or in combination of two or more.

The amount of the light stabilizer used is usually 0.01 to 3.0 molar ratio with respect to the cyanine dye. Further, a molar ratio of 3.0 or more may be used, but the dye concentration of the cyanine dye becomes low and the absorbance becomes low, which may cause inconvenience depending on the application. In addition, the effect may not be clear when the amount used is small. On the other hand, the cyanine dye to be light-stabilized is not particularly limited, but specifically, the following (C-1 to C-21) (Chemical formula 4 to
The compound shown in Chemical formula 7) is exemplified.

[0015]

[Chemical 4]

[0016]

[Chemical 5]

[0017]

[Chemical 6]

[0018]

[Chemical 7]

The phenol derivative in the present invention can be added and used as a light stabilizer in an optical recording medium using a thin film of a cyanine dye as a recording layer. When these light stabilizers are applied to an optical recording medium, they can be dissolved in various solvents together with the dye and then applied to the base of the recording medium to form a thin film.

[0020]

EXAMPLES The present invention will now be described in more detail with reference to examples. A polycarbonate plate used as a base of an optical recording medium is usually used as the colored body in the examples, but similar results can be obtained by using other bases such as glass and polymethacrylate.

Example 1 3 g of cyanine dye (C-1) and the following phenol compound (A) (Chemical formula 8)

[0022]

[Chemical 8]

2 g was put in 100 g of ethanol and stirred for 1 hour at room temperature, and then filtered using a membrane filter (PTEE, Toyo Roshi Kaisha, Ltd., pore size 1.0 μm) to obtain a dye solution. This dye solution was applied onto a polycarbonate plate substrate by spin coating. This colored polycarbonate substrate is a light resistance tester (DR manufactured by Irie Seisakusho).
Light was irradiated from a distance of 20 cm in 400 T). The fading rate of the cyanine dye at the absorption maximum wavelength of 715 nm after irradiation with light for 10 hours was 14.7%, which was a good result.

Examples 2 to 21 In exactly the same manner as in Example 1, the combination of the cyanine dye and the phenol compound was changed. The results are shown in Table 1 (Tables 1 and 2), and as in Example 1, good results were obtained.

COMPARATIVE EXAMPLE 1 When the procedure was carried out in Example 1 without adding any phenolic compound, the cyanine dye was considerably decomposed as shown in Table 1 (Table 2).

COMPARATIVE EXAMPLE 2 In Example 1, 2,6-di-t-butyl-4-methylphenol was used in place of the phenol compound (A) (Chemical formula 8), and Table 1 (Table 2 ), The cyanine dye was considerably decomposed.

[0027]

[Table 1]

[0028]

[Table 2]

[0029]

EFFECT OF THE INVENTION The phenolic compound of the present invention is a light stabilizer which is easy to handle, highly safe, and has a very excellent light stabilizing effect on cyanine dyes. Further, since it is also effective as a light stabilizer for an optical recording medium which is in high demand in recent years, it is possible to provide an optical recording medium excellent in light resistance.

Claims (2)

[Claims] 1. General formula (1) (Chemical formula 1) [In the formula, R represents an alkyl group, a cycloalkyl group, an alkoxyalkyl group, an optionally substituted phenyl group, or an aralkyl group. ] The light stabilizer of the phenolic cyanine dye represented by these. 2. An optical recording medium containing a light stabilizer for a phenolic cyanine dye represented by the general formula (1) (formula 1) according to claim 1.