JPH05193264A - Optical recording medium - Google Patents

Abstract

PURPOSE:To obtain an optical recording medium of a high shelf life stability organic material with superb sensitivity of writing by a laser beam by constituting the medium with a substrate and a recording layer containing a specific non-absorptive substance. CONSTITUTION:The subject medium consists of a substrate and a recording layer containing a light absorbing material expressed by formula (I) (X is NH3, OH; Y and Z is H, NHR, SR, OR, OSO2R, a cyano group, a holozen atom, R is substituted or unsnlatituted alkyl, cycloalkyl, an aryl group, an allyl group, a vinyl group, an aralkyl group, a heterocyclic group, an alkoxyalkyl group, an aralkylalkoxyalkyl group, an oxycarbonylalkyl group and an carboxyalkyl group). Consequently, the medium is highly sensitive to writing by a laser beam and besides, is of a high shelf life stability organic material.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to laser light, especially 520
The present invention relates to a high density optical recording medium capable of recording and reproducing information with a laser wavelength of around nm. More specifically, it relates to a high density optical recording body having a recording layer containing a specific light absorbing substance.

[0002]

2. Description of the Related Art Conventionally, an optical recording medium has been required to efficiently absorb the energy of a laser beam. Therefore, the absorption of a laser beam having a specific wavelength used for recording is large, and information is reproduced accurately. It is necessary that the reflectance with respect to a laser beam of a specific wavelength used for reproduction be high. Especially, when the wavelength of the semiconductor laser is shortened by using the generation of the second high frequency (SHG) using the optical nonlinear material, the wavelength is halved and the information amount is quadrupled. Since the efficiency is a few percent, a very sensitive recording medium is required.

[0003]

As optical recording media (recording materials) that have been studied so far, inorganic compounds such as metals, intermetallic compounds and chalcogenides have been proposed. Has a drawback in that it is susceptible to air oxidation, is difficult to store for a long period of time, is sensitive to ultraviolet rays and visible light, and is weak to sunlight and other light. As recording media using organic compounds, cyanine dyes, squarylium dyes, phthalocyanine dyes, etc. have been proposed. Generally, some cyanine dyes have poor stability, are difficult to store for a long period of time, and have low reflectance, so that they have drawbacks such as difficulty in reading information. Therefore, an object of the present invention is to provide an optical recording medium having an organic material having a high writing sensitivity by laser light and good storage stability as a recording layer.

[0004]

The above object can be achieved by the present invention described below. That is, the present invention is an optical recording medium comprising a substrate and a recording layer containing a light absorbing substance represented by the following general formula (1).

[Chemical 2] (In the formula, X is —NH ₂ or —OH, and Y and Z are —NH _2.
H, -NHR, -SR, -OR, -OSO 2 R, a cyano group or a halogen atom, R represents a substituted or unsubstituted alkyl group, a cycloalkyl group, an allyl group, an aryl group, a vinyl group, an aralkyl group, It represents a heterocyclic group, an alkoxyalkyl group, an aralkylalkoxyalkyl group, an oxycarbonylalkyl group or a carboxyalkyl group. )

[0005]

The optical recording medium of the present invention having the recording layer containing the light absorbing substance represented by the general formula (1) has high writing sensitivity by laser light and excellent storage stability.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in more detail with reference to the preferred embodiments. In the light absorbing substance represented by the general formula (1) in the optical recording medium of the present invention,
As the alkyl group, a methyl group, an ethyl group, a propyl group,
Butyl group, pentyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group, undecyl group, dodecyl group, tetradecyl group, pentadecyl group, hexadecyl group, heptadecyl group, octadecyl group, nonadecyl group,
Examples thereof include linear or branched alkyl groups such as eicosyl groups and the above alkyl groups having a substituent.

Examples of the substituent of the substituted alkyl group include halogen such as chlorine atom and bromine atom.
Examples of the cycloalkyl group include a cyclopentyl group, a cyclohexyl group, a cycloheptyl group and the like. Examples of the aryl group include a phenyl group, a tolyl group, a xylyl group, a biphenyl group and a naphthyl group. Examples of the aralkyl group include a benzyl group and a diphenylmethyl group. Examples of the alkoxy group constituting the alkoxyalkyl group or the aralkylalkoxyalkyl group include a methoxy group, an ethoxy group, a propoxy group, a butoxy group and the like, and an alkoxyalkyl group, an aralkylalkoxyalkyl group, a haloalkyl group or a carboxyalkyl group. As the alkyl group, the alkyl groups exemplified above can be exemplified.
As the aralkyl group of the aralkylalkoxyalkyl group, those exemplified above can be exemplified.

Of the light absorbing substances represented by the above general formula (1) used in the present invention, particularly preferable ones are:
Examples of X, Y and Z include a hydrogen atom, a halogen atom, a C _{1 to} C ₄ lower alkyl group, an alkylamino group, a hydroxyalkylamino group and a cyclohexylamino group. Examples of the substrate material of the present invention include glass, plastics, aluminum and the like. Plastics are preferable in terms of safety and light weight. Examples of the plastics include acrylic resin, methacrylic resin, polycarbonate resin, vinyl chloride resin, vinyl acetate resin, polyester resin, polyethylene resin, polypropylene resin, polyamide resin, polystyrene resin, epoxy resin, polysulfone resin and the like. A disk shape, a tape shape, or a sheet shape can be applied to the substrate shape. A groove for tracking is desirably formed on the substrate, and the groove shape is usually about 0.08 μm in depth and about 0.8 μm in width.

As a method of forming the recording layer, a general formula (1) is used.
Known methods such as a method of vacuum-depositing the compound of 1) on a substrate, a method of dissolving in a solvent and coating or dipping, a method of mixing with a resin solution and coating are known. As a vacuum evaporation method,
1 × 10 ⁻⁴ Torr or more, preferably 2 × 10 ⁻⁵
An example is a method of obtaining a vacuum deposited film on a substrate by heating the compound represented by the general formula (1) by resistance heating or the like at a high vacuum of Torr or higher. The film thickness is 200 to 4,0
00 angstroms, particularly 500 to 2,000 angstroms are preferred. The film formation by coating is obtained by spin-coating the compound represented by the general formula (1) dissolved or dispersed in a solvent.

As the solvent, water, alcohols such as methanol, ethanol, n-propyl alcohol, isopropyl alcohol, butyl alcohol, isobutyl alcohol, t-butyl alcohol, etc., monomethyl ether of ethylene glycol, monoethyl ether, monoisopropyl ether, Cellosolves such as monoisobutyl ether and monoisoamyl ether, ketones such as acetone, diethyl ketone, MIBK and methyl ethyl ketone,
Examples thereof include aromatic hydrocarbons such as benzene, toluene and xylene, dimethylformamide, tetrahydrofuran and the like. Further, a solution obtained by dissolving the compound of the general formula (1) together with a binder soluble in the above solvent may be similarly spin-coated. Examples of the binder include cellulose resins such as nitrocellulose, polyimide resins, polyamide resins, polystyrene resins, acrylic resins, polyester resins, and polycarbonate resins.
The recording layer of the optical recording medium of the present invention may be provided on both sides of the substrate, or may be provided on only one side.

Recording on the recording medium of the present invention obtained as described above is carried out in a recording layer of 1 μm on both sides or one side of the substrate.
It is performed by applying a laser beam focused to about m, preferably a semiconductor laser beam. In the portion irradiated with the laser light, thermal deformation of the recording layer such as decomposition, evaporation and melting due to absorption of laser energy occurs. The recorded information is reproduced by reading the difference in reflectance between the portion where the laser beam is thermally deformed and the portion where the laser beam is not thermally deformed. As a light source, a He-Ne laser,
Various lasers such as Ar laser and semiconductor laser can be used, but the semiconductor laser is particularly preferable in terms of cost and size. As the semiconductor laser, a laser having a central wavelength of about 520 nm can be used.

[0012]

EXAMPLES Next, the present invention will be described more specifically with reference to Examples and Comparative Examples. Example 1 A methanol solution (1% by weight) of the light absorbing substance represented by the general formula (1) was prepared, and 800 rpm / min. Was spin coated for 3 minutes. This thin film was irradiated with laser light having a central wavelength of 510 nm that passed through a non-linear optical material with a beam diameter reduced to about 0.5 μm, and the presence or absence of recording and the bit shape were observed with an optical microscope. As a result, a clear bit could be confirmed. Examples 2-8 and Comparative Examples 1-2 Under the conditions according to Example 1, other compounds of the general formula (1) shown in Table 1 and the compounds of Comparative Examples were used to form a film on a polycarbonate substrate, and then similarly. An evaluation was done. The results are summarized in Table 1.

[0013]

[Table 1]

[0014]

As described in detail above, the optical recording medium of the present invention having the recording layer containing the light absorbing substance represented by the general formula (1) has high writing sensitivity by laser light and storage. Excellent stability.

Claims (1)

[Claims] 1. An optical recording medium comprising a substrate and a recording layer containing a light absorbing substance represented by the following general formula (1). [Chemical 1] (In the formula, X is —NH ₂ or —OH, and Y and Z are —NH _2.
H, -NHR, -SR, -OR, -OSO 2 R, a cyano group or a halogen atom, R represents a substituted or unsubstituted alkyl group, a cycloalkyl group, an allyl group, an aryl group, a vinyl group, an aralkyl group, It represents a heterocyclic group, an alkoxyalkyl group, an aralkylalkoxyalkyl group, an oxycarbonylalkyl group or a carboxyalkyl group. )