JPH0564963A - Optical recording medium - Google Patents

Abstract

PURPOSE:To manufacture a high sensitivity optical recording medium which allows creation of a specific form of color association and the subsequent process to make a wavelength long by forming a color film using a casting technique with an imidazoquinoxalene color. CONSTITUTION:A recording layer based on imidazoquinoxalene color expressed by formula (R is an alkyl group; X<-> is anion; and n is 1 or 2) is formed on a substrate using a solution technique. Then the recording layer is exposed to a solvent vapor. Thus it is possible to ensure the easy creation of an associated state where imidazoquinoxalene color can be absorbed in the near infrared area of a color film, compared to film formation techniques such as vapor deposition and LB. Subsequently, the absorption peak becomes sharp remarkably and the wave length of the color becomes wide, thus enabling a highly sensitive optical recording medium to be manufactured. In addition, the recording and deletion of data in the recording medium can be performed by forming a hole or a recessed part which serves as an information signal with the irradiation of the recording layer with a laser beam.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical recording medium, a method of manufacturing the same, and a method of using the same.

[0002]

2. Description of the Related Art In recent years, research on optical recording media using organic dyes has been vigorously pursued. The recording principle of these optical recording media uses changes in light absorption characteristics due to intramolecular reaction caused by absorption of light by the dye, formation of bits by heat generated by absorption of light by the dye, and the like.

Many organic dyes such as phthalocyanine dyes and naphthalocyanine dyes have been reported as organic dyes used in such optical recording media. (Color material, 61 {4} 215
~ 226,1988, Idemitsu Petroleum Technology 31 , 4,68,1
988) On the other hand, the laser that has been developed to date as a laser used for optical recording has an oscillation wavelength of 830
8 nm because it is a semiconductor laser of nm and 780 nm
A light-absorbing substance that absorbs light having a wavelength near 00 nm must be used as the organic dye of the optical recording medium. A cyanine dye has absorption at a relatively long wavelength, but has poor light resistance. Phthalocyanine and naphthalocyanine dyes are excellent in photothermal stability, but have problems such as difficulty in increasing the wavelength.

Under these circumstances, it has been proposed to use a dye capable of having a special association state or crystal state as an organic dye. For example, as shown in JP-A-62-214536, by exposing a vapor-deposited film of a phthalocyanine dye to a solvent or by heating it, the crystal structure of the phthalocyanine dye is changed to have a longer wavelength, which matches the oscillation wavelength of a semiconductor laser. It was way.

Further, as shown in JP-A-63-167352, it has been shown that a cyanine dye film having a special structure formed by the LB method forms a J-aggregate, which is accompanied by absorption. There are also reports on recording media that utilize the change in spectrum.

However, in these conventional techniques, it is necessary to use the vapor deposition method and the LB method as the dye film forming method, and these methods are not necessarily highly productive film forming methods.

[0007]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an optical recording medium capable of increasing the wavelength of light absorption, having high sensitivity, and being manufactured with high productivity under such circumstances. Is.

[0008]

Means for Solving the Problems The inventors of the present invention have made extensive studies on various organic dyes and found that the following general formula was used as a recording material.

[0009]

[Chemical 2]

[0010] (wherein R represents an alkyl group, X ^- is .n representing the anion 1 or 2) is used imidazo quinoxaline-based dye represented by the dye special by forming a dye film by a casting method The inventors have found that the wavelength can be made longer because of the (specific) association state, and at the same time, the absorption spectrum of the dye film is significantly sharpened and the absorbance is increased, and the present invention has been completed.

That is, the present invention relates to an optical recording medium for recording information by irradiating a recording layer provided on a substrate with laser light.

[0012]

[Chemical 3]

(Wherein R represents an alkyl group, X ⁻ represents an anion, and n represents 1 or 2), and the imidazoquinoxaline dye has a recording layer containing the imidazoquinoxaline dye as a main component. The present invention relates to an optical recording medium that forms an association state having absorption in the near infrared region in a dye film.

The method for synthesizing the imidazoquinoxaline dye is described in USP 3,431,111, C.I. A. , 72 , 6822
2 (1970). In the case of the optical recording medium used in the present invention, the alkyl chain length of the alkyl group represented by R preferably has 1 to 10 carbon atoms in order to form an aggregate.

A preferred embodiment of the present invention will be described. Basically, a recording layer mainly containing the imidazoquinoxaline dye in an associated state is provided on a substrate.
A reflective layer of Al, Cr, Ge, Pt or the like may be provided between the substrate and the recording layer, or a protective layer may be provided on the recording layer.

Next, a method of manufacturing the optical recording medium will be described. That is, a manufacturing method is characterized in that a recording layer is formed on a substrate by a solution method such as a generally known spin coating method, and then the recording layer is exposed to a vapor of a solvent, whereby a conventional vapor deposition method, an LB method or the like is formed. Compared with the membrane method, it became possible to easily cause the imidazoquinoxaline dye to form a special (specific) aggregate. The solvent is not particularly limited as long as the solvent in which the imidazoquinoxaline dye is soluble is used, but examples thereof include 2,2,2-trifluoroethanol, methanol, ethanol, butanol, chloroform and the like.

In some cases, a solvent having a relatively low evaporation rate is used, or the spin-coating conditions are changed to form an aggregate only by spin-coating. In that case, it is possible to omit the step of exposing to steam after film formation, which is preferable.

As the aggregate is formed by the above-mentioned method, the absorption spectrum changes greatly. That is, the absorption peak becomes remarkably sharp and the wavelength becomes long, so that it is possible to manufacture a highly sensitive optical recording medium.

The recording and erasing method of the recording medium used in the present invention can be carried out by irradiating the recording layer with a laser beam to form a hole or a recess which becomes an information signal. Recording is performed by irradiating the recording layer with a laser beam having an absorption wavelength of the imidazoquinoxaline-based dye aggregate to eliminate the aggregate in the irradiated portion, and the recording medium is partially (entirely) exposed to solvent vapor. It is also possible to cause the imidazoquinoxaline dye to form an association state again and be erased by the exposure.

In the latter recording method by disappearance of aggregates,
Since the dye is not deformed or removed, recording can be performed with relatively low energy.

[0021]

EXAMPLE An imidazoquinoxaline dye having the structure shown below was prepared.

[0022]

[Chemical 4]

A coating solution was prepared by dissolving the solvent in 2,2,2-trifluoroethanol.

Using this, a dye film was formed on a glass substrate by a spin coating method to prepare a sample. The absorption spectrum at this time is shown in 1 of FIG. Next, when the sample was exposed to the vapor of 2,2,2-trifluoroethanol, a change in the color of the dye film was visually recognized. The absorption spectrum at this time is shown in 2 of FIG.

It can be seen that the absorption peak is sharper than that of 1 in FIG. 1 and the wavelength is lengthened. By irradiating a laser beam having a wavelength of 830 nm in this state, the aggregate disappears, and the absorption spectrum is taken as shown in FIG.
It is understood that the record was erased from the fact that the same result as was obtained.

Reference numeral 3 in FIG. 1 is a solution spectrum of the above-mentioned imidazoquinoxaline dye. (Λ _max 698 nm, ε
= 1.7 × 10 ⁵ l / mol) Comparative Example 1 An imidazoquinoxaline dye having a structure shown below was used as a dye.

[0027]

[Chemical 5]

A sample was prepared in the same manner as in the example except that it was used and exposed to the vapor of the solvent, but no spectral change as shown in the example was observed.

Comparative Example 2 A compound having the structure shown below was used as a dye.

[0030]

[Chemical 6]

A sample was prepared in the same manner as in the example except that it was used and exposed to the solvent vapor, but no spectral change as shown in the example was observed.

[0032]

When the dye forming the association state of the present invention is used as the recording material, the optical recording medium has high sensitivity because of its high absorbance. When the dye is used, an aggregate can be easily formed even in a dye film produced by a casting method (spin coating method) which is more advantageous in productivity and cost than the conventional film forming method.

[Brief description of drawings]

FIG. 1 shows an absorption spectrum of a dye (Example) used in the present invention.

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Noboru Sasa 1-3-6 Nakamagome, Ota-ku, Tokyo Within Ricoh Co., Ltd.

Claims (4)

[Claims] 1. An optical recording medium for recording information by irradiating a recording layer provided on a substrate with laser light, wherein the following general formula: (Wherein R represents an alkyl group, X ⁻ represents an anion, and n represents 1 or 2), and the imidazoquinoxaline dye is contained in the dye film. An optical recording medium characterized by forming an association state having absorption in the near infrared region. 2. The method for producing an optical recording medium according to claim 1, wherein the recording layer containing an imidazoquinoxaline dye as a main component is formed by a casting method and then exposed to the vapor of a solvent. 3. An optical recording method using the optical recording medium according to claim 1, wherein the recording layer is irradiated with a laser beam to form a hole or a recess, and the hole or the recess is used as an information signal. 4. The optical recording medium according to claim 1, wherein the recording layer forming the aggregate is irradiated with a laser beam having an absorption wavelength of the aggregate so that the aggregate in the irradiated portion disappears. Recording and erasing the information by causing the imidazoquinoxaline dye to associate again with the imidazoquinoxaline dye by exposing the recording medium at least partially to the vapor of a solvent. .