JPS63278891A - Optical recording medium - Google Patents

Abstract

PURPOSE:To easily form a recording layer itself by coating and to enhance the recording layer in reflectance to obtain a good contrast in recording with superior light fastness and resistance to a regenerated light, by providing the recording layer containing an azo light-absorbing dye stuff having a specific chemical constitution on a substrate. CONSTITUTION:A recording medium is composed by providing a recording layer containing an azo light-absorbing dye stuff shown by a general formula I on a substrate. In the formula, Q<1>, Q<2>, Q<3>, and Q<4> represent benzene or naphthalene ring which may be substituted by amino, alkyl, alkoxy, acylamino, hydroxyl, or SO3M group; R<1> and R<2> represent hydroxyl or amino group; and M represents hydrogen, alkali metal, amino, or ammonium salt. The aforesaid azo light-absorbing dye stuff for forming the recording layer is easily formed by being directly applied to a substrate because of its superior solubility in a hydrophilic solvent and makes the recording layer high in reflectance with a good contrast as well as excellent in light fastness and resistance to a regenerated light.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to optical recording media. The optical recording medium of the present invention can be advantageously used as a recording medium for high-density information recording and storage using laser light or the like, and for recording and reproducing the same.

(Prior Art) Optical recording using laser light or the like is capable of recording and storing information at a high density, and the recording can be easily reproduced and used. An example thereof is an optical disk.

In general, a single-optical disk is a disk in which high-density information is recorded by irradiating a laser beam focused on a thin recording layer of about KS/μm provided on a circular base. The recording is performed without causing thermal deformation such as decomposition, evaporation, or melting in the recording layer at that location due to absorption of the irradiated laser beam energy. Further, recorded information is reproduced by reading the difference in reflectance between a portion where deformation has occurred and a portion where deformation has not occurred using a laser beam.

Therefore, optical recording media must absorb the energy of laser light efficiently, so they must have high absorption of laser light of a specific wavelength used for recording, and must have a high absorption capacity for accurate reproduction of information. It is necessary that the reflectance for the laser beam of the specific wavelength used is high.

Various configurations of this type of optical recording medium are known. For example, Japanese Patent Application Laid-Open No. 5S-Q'70JJ discloses a method in which a single layer of a phthalocyanine dye is provided on a substrate.

Phthalocyanine dyes have drawbacks such as low sensitivity, high decomposition point and difficulty in vapor deposition, and extremely low solubility in organic solvents, making it difficult to coat them to form a recording layer.

Also, Tokukai Akira! GG33 Dada publication discloses a recording layer in which a phenalene dye is provided, and JP-A-22-1793 discloses a recording layer in which a naphthoquinone dye is provided.

Although such dyes have the advantage of being easy to vapor deposit, they have the disadvantage of low reflectance. If the reflectance is low, the contrast between the reflectance of the portion recorded by the laser beam and the unrecorded portion will be low, making it difficult to reproduce the recorded information.

Also, Tokukai Aki? - KotI49 Publication, JP-A No. 3? −
No. 6-092 and JP-A-19-7/ZA-25 disclose recording layers in which a cyanine dye is provided. Although such dyes have the advantage of being easy to coat by coating, they have the disadvantage of poor light resistance and deterioration due to reproduction light (Problems to be Solved by the Invention) The present invention The recording layer itself is easily formed by
The object of the present invention is to provide an optical recording medium in which the recording layer has a high reflectance and good recording contrast, and is also excellent in light resistance and resistance to reproduction light.

(Means for Solving the Problems) As a result of various studies to solve the above-mentioned problems, the present inventors have developed a recording layer containing an azo light-absorbing dye having a specific chemical structure on a substrate. This purpose could be easily achieved by establishing a

That is, the optical recording medium of the present invention has a substrate having the general formula (1
) (In the formula, Q, I, Q3, Qs and q4 represent a benzene ring or a naphthalene ring, and may be substituted with an amino group, an alkyl group, an alkoxy group, an acylamino group, a hydroxyl group or an 80.M group. R1 and R1 represent a hydroxyl group or an amine group, and M represents a hydrogen atom, an alkali metal, an amine, or an ammonium salt. It is.

In the azo dye represented by the general formula (1), the alkyl group includes a methyl group or an ethyl group, the alkoxy group includes a methoxy group, an ethoxy group, or a butoxy group, and the acyl group of the acylamino group includes , an acetyl group, a propionyl group or a benzoyl group.

In addition, M includes alkali metals such as lithium, sodium, and potassium; amines such as mono-, di-, or triethanolamine and methyljetanolamine; ammonium such as ammonium, trimethylhydroxyethyl'ammonium, and tetramethylammonium; Salt is an example.

The azo dye represented by the general formula (1) is 100 to 1
It has absorption in a wavelength band of 1000 nm, and has a molecular absorption coefficient of 10' to /gecrn-'.

The compound of the present invention can be prepared by ordinary diazotization, for example, according to the description in "1 New Dye Chemistry" by Yutaka Hosoda (Showa ≠ published on January 27, 2007), Gihodo, page '403 from the bottom, line C to page aOa, line lI. It can be manufactured by stacking couplings.

The optical recording medium of the present invention basically consists of a substrate and a recording layer, but if necessary, an undercoat layer can be provided on the substrate and a protective layer can be provided on the recording layer.

The substrate in the present invention may be transparent or opaque to the laser beam used. As the material of the substrate, supports for this type of recording medium, such as glass, plastic, paper, plate-shaped or foil-shaped metal, can be used, but plastic is preferable from various points of view.

Examples of the plastic include acrylic resin, epoxy resin, methacrylic resin, vinyl acetate resin, vinyl chloride resin, nitrocellulose, polyethylene resin, polypropylene resin, polycarbonate resin, polyimide resin, polysulfone resin, and the like.

The thickness of the recording layer containing the azo light-absorbing dye as the information recording layer in the optical recording medium of the present invention is iooλ~Sμ
m1 is preferably zoo~Jμm.

To form the recording layer, a commonly used thin film forming method such as a sputtering method, a doctor blade method, a casting method, a spinner method, or a dipping method is used. The recording layer can be formed using an azo light-absorbing dye alone or in combination with a binder. As the binder, resins such as polyvinyl alcohol, polyvinylpyrrolitone, nitrocellulose, cellulose acetate, polyvinyl butyral, and polycarbonate are used. The content of the azo light-absorbing dye in the recording layer is preferably 1 weight or more based on the resin.

The above-mentioned doctor blade method, cast method, spinner method,
When forming a recording layer by a coating method such as a dipping method, especially a spinner method, a coating solvent is used, and examples of the solvent include water, pro-7form, dibromoethane, tetrachloroethane, ethyl cellosolve, Solvents such as xylene, chlorobenzene, and cyclohexanone are preferably used. In the case of film formation by spinner method, the rotation speed is 200~
! r000 rpm is preferable, and after the spin code, treatment such as heating or exposure to solvent vapor may be performed depending on the case.

The recording layer of the optical recording medium of the present invention contains a transition metal chelate compound (for example, acetylacetonate chelate, bisphenyldithiol, salicylaldehyde) as a -heavycyclic oxygen quencher for the purpose of improving the stability and light resistance of the recording layer. oxime, bisdithiol-α-diketone, etc.)
may be contained.

Furthermore, dyes of the same type and dyes of other types can be used in combination in the recording layer of the present invention. Examples of other pigments include indophenol pigments, triarylmethane pigments, azo pigments, cyanine pigments, and squalirium pigments.

The recording layer in the optical recording medium of the present invention may be provided on both sides of the substrate or only on one side.゛Recording on the optical recording medium of the present invention is carried out by irradiating the recording layer provided on both sides or one side of the substrate with laser light, preferably semiconductor laser light, focused to about /μW&. In the area irradiated with the laser beam, thermal deformation of the recording layer such as decomposition, evaporation, and melting occurs due to absorption of the laser beam energy, and information is recorded.

The recorded information is reproduced by reading the difference in reflectance between areas where thermal leopard deformation has not occurred and areas where thermal leopard deformation has occurred.

Lasers used for recording and reproducing the optical recording medium of the present invention include N, , He-C (lSAr).

Examples include He-No, ruby, semiconductor, and dye lasers, but semiconductor lasers are particularly preferred because of their light weight, ease of handling, and compactness.

(Example) The present invention will be described in more detail below with reference to Examples, but the present invention is not limited to these Examples.

Example 1 λmax (Wed) 6! rAnmDek4nm t (molecular extinction coefficient) A, 0AX104 Optical recording medium: Azo dye/9 represented by the above formula in water:methanol-
,? :/ in a mixed solvent SO# and filtered through a 06-μ filter to obtain a solution.

This solution-1 was dropped onto a polycarbonate resin substrate (/JOvaφ) with grooves (groups) formed by injection molding with a depth of OOλ and a width of 0.7μ, and was applied using a spinner method.
000 rpm and dried at 60° C. for 70 minutes. It was coated on a glass plate under the same conditions and the coated film thickness was measured by Talystep and it was found to be ζ and OQλ. As shown in Figure 7, the maximum absorption wavelength of the coating film is 6 g On
m, and the shape of the spectrum was wide.

When this coating film was irradiated with a semiconductor laser beam having a center wavelength t j Onm and a beam diameter of approximately 1 μm, holes (bits) with extremely clear outlines were formed. 700/N
The ratio was high, and the light resistance and resistance to reproduction light were good.

Example λmax (aqueous solution) for azo dyes represented by the following general formula (I) and having various structural formulas shown in Table 1, and a group of azo dyes according to the method of Example 1. The maximum absorption wavelength of the coating film applied on the polycarbonate resin substrate was as shown in Table 0.0 (Effects of the Invention) The optical recording medium of the present invention is characterized in that the azo light-absorbing dye for forming the recording layer is hydrophilic. (Water, cellosolve type) It has excellent solubility in solvents, so it can be easily formed by direct coating on injection molded plastic substrates, and the recording layer has high reflectance, good contrast, and light resistance and resistance to reproduction light. It also has excellent resistance.

[Brief explanation of the drawing]

Figure -/ illustrates the absorbance and reflectance curves of the coating film of Example 1. Applicant: Mitsubishi Chemical Industries, Ltd. Agent: Patent Attorney Nagakagawa - (and 7 others)

Claims (1)

[Claims] (1) There is a general formula (I) ▲mathematical formula, chemical formula, table, etc. on the substrate▼...(I) (In the formula, Q^1, Q^2, Q^3 and Q^4 are benzene rings or naphthalene rings. represents an amino group, an alkyl group, an alkoxy group, an acylamino group, a hydroxyl group, or an SO
_2M may be substituted. R^1 and R^2 represent a hydroxyl group or an amino group, and M
represents a hydrogen atom, an alkali metal, an amine or an ammonium salt. ) An optical recording medium comprising a recording layer containing an azo light-absorbing dye.