JP2749079B2 - Optical recording medium - Google Patents

Description

The present invention relates to an improvement in an optical recording medium used for an optical disk memory device or the like.

(Prior Art) A disk-shaped optical recording medium in which a recording layer is provided on a plastic or glass substrate is used for recording and reproducing information using a laser beam. As a material of the recording layer of the optical recording medium, a metal having a low melting point such as tellurium has been used. However, such a recording layer has low recording density, insufficient sensitivity, poor storage stability, and is toxic to the human body. Further, since the recording layer made of the metal thin film is formed on the substrate by vapor deposition, the cost increases.

An optical recording medium having a recording layer using an organic dye thin film instead of the recording layer made of a metal has been prepared. Examples of such dyes include polymethine dyes, phthalocyanine dyes, dithiol metal complex dyes, and naphthoquinone dyes. Since such an organic dye is dissolved in an organic solvent, spin coating is possible when forming a thin film on a substrate, and the productivity is excellent. It is safe because it has no toxicity. However, when information is repeatedly recorded, reproduced, and erased by laser light using such a recording medium or stored for a long period of time, the recording layer is deteriorated and the sensitivity is reduced. Alternatively, there is a disadvantage that the carrier / noise ratio (C / N ratio) is reduced.

In order to solve such disadvantages, for example, Japanese Patent Application Laid-Open
No. 30564 discloses that a polymethine dye is used as a main component,
An optical recording medium having a recording layer to which a quencher having a specific structure is added is disclosed. The function of the quencher improves the deterioration of the recording layer due to the laser beam or the long-term storage, particularly the deterioration of the recording layer due to oxygen in the air. However, the effect is still not enough.
Furthermore, since this quencher has poor solubility in an organic solvent, it is difficult to uniformly coat the quencher together with a dye on a substrate by spin coating.

(Problems to be Solved by the Invention) The present invention is to solve the above-mentioned conventional problems, and aims at high recording density and sensitivity, little deterioration due to repeated use or long-term storage, and An object of the present invention is to provide an optical recording medium having a recording layer that is not toxic to the human body. Another object of the present invention is to provide an optical recording medium using a recording layer having the above-mentioned excellent properties, in which an organic dye which is easy to prepare a thin film is used. Still another object of the present invention is to provide an optical recording medium comprising a recording layer containing an organic dye and a suitable quencher and having the above-mentioned excellent properties.

(Means for Solving the Problems) The optical recording medium of the present invention is an optical recording medium in which a recording layer is provided directly or via an undercoat layer on a substrate, wherein the recording layer is an organic dye, and Including the phosphorus-containing metal complex having structural formula (I), thereby achieving the above object: Where M is Na, Mg, K, Ca, Sr, Ba, Sc, Y, Ti, Zr, V, Nb, Cr, M
n, Fe, Co, Ni, Pd, Cu, Ag, Zn, Cd, Al, Ga, In, Si, Ge, Sn, Pb, As,
Sb, Te, tin substituted with an organic group, or silicon substituted with an organic group; R ₁ and R ₂ each independently represent an alkyl group, an alkoxy group, an aryl group, an aryloxy group, an aralkyl group, an aralkyloxy group Wherein the aryl group, the aryloxy group, the aralkyl group and the aromatic nucleus of the aralkyloxy group include a halogen atom, an alkyl group, an aryl group, an alkoxy group, an aryloxy group, a cyano group,
Nitro group, amino group, ester group, alkylamino group,
At least one of a hydroxyl group, a sulfonyl group and a sulfonamide group may be substituted; X is O or S; and n is an integer of 1 to 4.

As the organic dye which is the main component of the recording layer of the optical recording medium of the present invention, any of the organic dyes used for recording on the optical recording medium can be used. For example, polymethine dyes (including cyanine dyes), phthalocyanine dyes, dithiol metal complex dyes, naphthoquinone dyes, anthraquinone dyes, triarylmethane dyes, aminium dyes, immonium dyes, squarylium dyes There are pigments and the like. Among the phosphorus-containing metal complexes represented by the formula (I), commonly used compounds are shown in Table 1.

The phosphorus-containing metal complex can be prepared by a known method. For example, the compound represented by (I) -1 in Table 1 is
Reacting diphenylphosphine with sulfur It is obtained by making NiCl ₂ or the like act on this.

The phosphorus-containing metal complex has a function of suppressing the deterioration of the organic dye by quenching (trapping) singlet oxygen generated by laser light irradiation. The amount of the phosphorus-containing metal complex to be used is 1 to 150 parts by weight, preferably 5 to 50 parts by weight, based on 100 parts by weight of the organic dye. If the amount of the phosphorus-containing metal complex is too small, the effect of preventing deterioration of the organic dye cannot be obtained. Conversely, if it is excessive, the function as a recording medium is reduced.

As the substrate used for the optical recording medium of the present invention, any of the materials used as the substrate of the ordinary optical recording medium can be used. Since the optical recording medium of the present invention is preferably prepared by a coating method using an organic solvent described below, a material that does not dissolve or swell with the organic solvent is selected. Examples include plastics such as polymethyl methacrylate, polycarbonate, acrylic resin, epoxy resin, phenolic resin, polyvinyl chloride, polyamide, and polyimide; glass; metal; and ceramic.

Between the substrate and the recording layer of the optical recording medium of the present invention,
An undercoat layer can be provided if necessary, and a protective layer can be provided on the surface of the recording layer. As the undercoat layer and the protective layer, the compositions used for ordinary undercoat layers and protective layers are used, respectively. Further, various additives may be contained in the recording layer, undercoat layer and protective layer of the optical recording medium of the present invention. Examples thereof include stabilizers such as antioxidants and ultraviolet absorbers; dispersants; flame retardants; plasticizers; lubricants; water repellents; antistatic agents;

The optical recording medium of the present invention is prepared by forming an undercoat layer on a substrate, if necessary, and forming a thin film containing an organic dye and a phosphorus-containing metal complex on the surface thereof. Known methods such as a coating method, a vacuum evaporation method, a sputtering method, and a CDV method are used for forming the thin film. Since the phosphorus-containing metal complex of the present invention is excellent in solubility in an organic solvent, a coating method using an organic solvent is advantageous from the viewpoint of workability. Specifically, the organic dye and the phosphorus-containing metal complex are dissolved in an appropriate organic solvent and applied to a substrate by a spin coating method, a dipping method, a doctor blade method, a roll coater method, etc., to form a thin film.

Examples of the solvent used include alcohols such as methanol; ketones such as acetone; esters such as methyl acetate; ethers such as methyl cellosolve; amides such as dimethylformamide; sulfoxides such as dimethyl sulfoxide; Aromatic hydrocarbons; halogenated hydrocarbons such as dichloroethane. These can be used alone or as a mixture. The thickness of the thin film (recording layer) is generally 0.02 μm to 10 μm, preferably 0.02 μm to 5 μm.

Thus, an optical recording medium is prepared by a simple operation by a coating method using an organic solvent. Such an optical recording medium has high sensitivity and a high recording density. Further, since a specific phosphorus-containing metal complex is contained, deterioration is unlikely to occur even when information is repeatedly written, read and erased, and long-term storage is possible.

(Example) Hereinafter, the present invention will be described with reference to examples.

Example 1 (A) Preparation of optical recording medium: A polymethyl methacrylate substrate having a thickness of 1.2 mm and a diameter of 13 cm was prepared. 1,1 ', 3,3,3', 3'-hexamethyl-2,2 '
1,2-Phosphorus-containing metal complex represented by (I) -1 in Table 1 with respect to 100 parts by weight of indotricarbocyanine perchlorate (polymethine dye, referred to as dye A) Dichloroethane-methyl ethyl ketone (9: 1wt
Ratio) The mixture was dissolved in a mixed solution, and this solution was spin-coated on the substrate to form a recording layer having a thickness of 0.1 μm, thereby obtaining an optical recording medium.

(B) Performance evaluation of optical recording medium: Writing was performed by irradiating the optical recording medium prepared in (A) with a semiconductor laser beam having a wavelength of 830 nm at an irradiation surface output of 7 mW, a cotton speed of 1.5 m / sec, and a frequency of 2 MHz. Was. Next, the same laser light was applied, and the irradiation surface output was set to 0.
Regeneration was performed by irradiating 5 mW, and the waveform was spectrally analyzed to measure the C / N ratio. Table 2 shows the results.

Next, a new recording medium was added at 25 ° C and 60% humidity.
After irradiating a 10,000 lux xenon lamp for 24 hours, the reflectance and C / N ratio were measured again. Table 2 shows the results of the light resistance test. Table 2 also shows the results of Examples 2 to 8 and Comparative Examples 1 to 3.

Example 2 The same as Example 1 except that the compound represented by (I) -2 in Table 1 was used as the phosphorus-containing metal complex at a ratio of 20 parts by weight to 100 parts by weight of the dye A.

Example 3 The same as Example 1 except that the compound represented by (I) -3 in Table 1 was used as the phosphorus-containing metal complex in an amount of 5 parts by weight based on 100 parts by weight of the dye A.

Example 4 The same as Example 1 except that the compounds shown in (I) -4 of Table 1 were used as the phosphorus-containing metal complex.

Example 5 Instead of Dye A, 3,3'-diethyl-2,2'-thiatricarbocyanine perchlorate (cyanine dye,
Example 1 except that the compound represented by (I) -3 in Table 1 was used in an amount of 5 parts by weight based on 100 parts by weight of the dye B as the phosphorus-containing metal complex. 1
Is the same as

Example 6 Dye B was used instead of Dye A, and a compound represented by (I) -5 in Table 1 was used as a phosphorus-containing metal complex.
It is the same as Example 1 except that 10 parts by weight was used for 100 parts by weight of B.

Example 7 Instead of Dye A, 1,1 ', 3,3,3', 3'-hexamethyl-4,5-4 ', 5'-dibenzo-2,2'-indotricabocyanine perchlorate ( Polymethine dye, dye C
Example 1 except that the compound represented by (I) -3 in Table 1 was used in an amount of 5 parts by weight based on 100 parts by weight of the dye C as the phosphorus-containing metal complex. The same is true.

Example 8 Instead of Dye A, Dye C was used, and a compound represented by (I) -6 in Table 1 was used as a phosphorus-containing metal complex at a ratio of 20 parts by weight to 100 parts by weight of Dye C. Except for this, the operation is the same as that of the first embodiment.

Comparative Example 1 Example 1 except that no phosphorus-containing metal complex was used.
Is the same as

Comparative Example 2 The same as Example 5 except that the phosphorus-containing metal complex was not used.

Comparative Example 3 Example 7 except that the phosphorus-containing metal complex was not used.
Is the same as

From Table 2, it can be seen that the optical recording medium of the present invention has very little deterioration due to light and has excellent durability.

(Effect of the Invention) According to the present invention, an optical recording medium having high sensitivity and high recording density can be obtained. In this optical recording medium, the recording layer is hardly deteriorated even when information is repeatedly written, read, and erased, and can be repeatedly used and stored for a long time. This optical recording medium can be prepared at low cost by a simple operation by a coating method using a solvent.

Claims (2)

(57) [Claims] 1. An optical recording medium having a recording layer provided directly or via an undercoat layer on a substrate, wherein the recording layer contains an organic dye and a phosphorus-containing metal complex having the following structural formula (I). Including, optical recording media: Where M is Na, Mg, K, Ca, Sr, Ba, Sc, Y, Ti, Zr, V, Nb, Cr, Mn, F
e, Co, Ni, Pd, Cu, Ag, Zn, Cd, Al, Ga, In, Si, Ge, Sn, Pb, As, Sb,
Te represents tin substituted with an organic group, or silicon substituted with an organic group; R ₁ and R ₂ each independently represent an alkyl group, an alkoxy group, an aryl group, an aryloxy group, an aralkyl group, or an aralkyloxy group; , The aryl group, the aryloxy group, the aralkyl group and the aromatic nucleus of the aralkyloxy group include a halogen atom, an alkyl group, an aryl group, an alkoxy group, an aryloxy group, a cyano group,
Nitro group, amino group, ester group, alkylamino group,
At least one of a hydroxyl group, a sulfonyl group and a sulfonamide group may be substituted; X is O or S; and n is an integer of 1 to 4. 2. The optical recording medium according to claim 1, wherein M of said phosphorus-containing metal complex is Co, Ni, Cu or Zn.