JPH089260B2 - Optical information recording medium - Google Patents

Description

TECHNICAL FIELD The present invention relates to an optical information recording medium suitable for writing and recording by a laser, particularly a semiconductor laser.

[Prior Art] Conventionally, there is known an information recording / reproducing apparatus for irradiating a rotating disc-shaped information recording medium with a laser beam to record / reproduce information. Then, as an information recording medium used in this kind of information recording apparatus, there has been proposed one in which a recording layer made of a low melting point metal or a low melting point metal and a dielectric is provided on a substrate. However, these are poorly stored,
It has drawbacks such as low resolution, low recording density, and high cost.

Therefore, the present inventors have found that when a dye thin film is provided on a substrate as a result of various studies, a recording medium with improved write sensitivity and reflectance and a high read S / N ratio can be obtained, and already proposed it. ing. However, under the present circumstances, such a recording medium is still insufficient in stability against light and heat, storability against reproduction light after recording, and the like.

[Objective] The present invention has been made in view of the above situation, and its main purpose is to improve light resistance of an optical information recording medium and prevent reproduction deterioration.

[Structure] According to the present invention, firstly, in the optical information recording medium comprising an organic dye thin film recording layer containing a polymethylene dye as a main component on a substrate directly or through an undercoat layer, General formula for at least one of the pulling layer and recording layer (In the formula, Z represents an atomic group necessary for completing a substituted or unsubstituted carbocyclic ketone, and an aromatic ring may be fused to the carbocyclic ring, and R ₁ and R ₂ are the same or not. Or may be different and each represents a substituted or unsubstituted alkyl group or a substituted or unsubstituted aryl group, X represents an acid anion, m represents 0, 1 or 2 and A is (N represents 1 or 2) or (When m = 2), R ₃ represents a hydrogen atom, an alkyl group or an alkoxy group. ) Is provided, and secondly, an organic dye thin film recording layer containing a polymethylene dye as a main component is directly formed on a substrate or through an undercoat layer. In an optical information recording medium having a protective layer further provided thereon, at least one of the subbing layer, the recording layer and the protective layer has the general formula (In the formula, Z represents an atomic group necessary for completing a substituted or unsubstituted carbocyclic ketone, and an aromatic ring may be fused to the carbocyclic ring, and R ₁ and R ₂ are the same or not. Or may be different and each represents a substituted or unsubstituted alkyl group or a substituted or unsubstituted aryl group, X represents an acid anion, m represents 0, 1 or 2 and A is (N represents 1 or 2) or (When m = 2), R ₃ represents a hydrogen atom, an alkyl group or an alkoxy group. And an optical information recording medium comprising a compound represented by

Specific examples of the compound represented by the above general formula are shown below, but the present invention is not limited thereto.

The compound of the above general formula in the present invention can be contained not only in the recording layer but also in other layers, but in the dye recording layer it is contained in an amount of 2 to 60% by weight, preferably 5 to 40% by weight based on the total solid content. It can be contained in a proportion of 2 to 100% by weight, preferably 20 to 100% by weight, based on the total solid content in the undercoat layer or the protective layer. When the above compound is contained in two or more layers, it is added to each layer in a ratio within the above range for each layer.

The optical information recording medium of the present invention basically has a recording layer provided on a substrate, but an undercoat layer may be provided between the substrate and the recording layer, or a protective layer may be provided on the recording layer. Layers may be provided. In addition, the pair of recording media thus constructed may have an air sandwich structure in which the recording layer is placed inside and is sealed with another substrate through a space, or a close contact sandwich (sticking layer) adhered through a protective layer. (Matching structure).

Next, the materials constituting the optical information recording medium of the present invention and the required characteristics of each layer will be described.

1) Substrate As a necessary characteristic of the substrate, the substrate must be transparent to the laser light used only when recording / reproducing is performed from the substrate side, and need not be transparent when performing from the recording side. As the substrate material, for example, plastic such as polyester, acrylic resin, polyamide, polyolefin resin, phenol resin, epoxy resin, polyimide, glass, ceramic or metal particles can be used.

It should be noted that the surface of the substrate may be pre-formatted for address signals or the like, or pre-grooves for guide grooves may be formed.

2) Recording layer The recording layer is capable of recording some information by causing some kind of optical change by irradiation of laser light, and its main component is polymethine dye. Representative examples of polymethine dyes include cyanine dyes, merocyanine dyes, croconium dyes, and pyrylium dyes.

The recording layer contains a polymethine dye as a main component, but two or more of the above dyes may be combined in order to improve recording characteristics and stability. Other dyes such as phthalocyanine dyes, tetrahydrocholine dyes, dioxazine dyes, trioxazine dyes, trioxazine dyes Phenothiazine, Phenanthrene, Anthraquinone (Indanthrene), Xanthene, Triphenylmethane, Azulene dyes or metals such as In, Sn, Te, B
It may be mixed and dispersed with i, Al, Se, Ag, Cu or the like or a metal compound such as TeO ₂ or SnO or laminated. In addition, the recording layer may further contain a polymer material, a storage stabilizer (for example, a metal complex, a phenol compound, etc.), a dispersant, a flame retardant, a lubricant, an antistatic agent, a plasticizer and the like.

When the recording layer contains the compound of the above general formula in the present invention, the weight ratio of the polymethine dye to the compound is adjusted.
30/70 to 99/1, preferably 60/40 to 95/5.

The recording layer can be formed by a conventional method such as vapor deposition, sputtering, CVD or solution coating.
In the case of solution coating, organic solvents such as alcohols,
Ketones, amides, ethers, sulfoxides, esters, aliphatic halogenated hydrocarbons, polymethine dyes in aromatics In some cases, the above compounds are dissolved to spray, spinner, dip, blade, roller, etc. It is carried out by a conventional coating method. The thickness of the recording layer is 100Å-10 μm, preferably 200Å-2 μm.

3) Undercoat layer The undercoat layer comprises (a) improved adhesion, (b) water or gas barrier, (c) improved storage stability of the recording layer and (d) improved reflectance, (e). Protection of the substrate from solvents,
(F) It is used for the purpose of forming pregrooves. For the purpose of (a), it is possible to use various polymeric materials such as ionomer resins, polyamide resins, vinyl resins, natural polymers, silicones, liquid rubbers, and silane coupling agents.
For the purposes of (b) and (c), in addition to the above polymeric materials, inorganic compounds such as SiO ₂ , MgF ₂ , SiO, TiO ₂ , ZnO, TiN, SiN
Such as metals or semi-metals such as Zn, Cu, S, Ni, Cr, Ge, Se, A
u, Ag, Al or the like can be used, and for the purpose of (d), a metal such as Ag, Al, a pigment having a metallic luster such as a methane-based pigment, a xanthene-based pigment or the like can be used. For the purposes of the above (e) and (f), an ultraviolet curable resin, a thermosetting resin, a thermoplastic resin or the like can be used. The thickness of the undercoat layer is 0.1 to 30 μm, preferably 0.2
-10 μm is suitable.

4) Protective layer The protective layer is provided for the purpose of protecting the recording layer from scratches, dust, dirt, etc., and improving the storage stability and reflectance of the recording layer. The same material as the undercoat layer is used as the material. can do. The thickness of the protective layer is 0.05 μm or more, preferably 5 μm or less.

The undercoat layer and the protective layer may contain a stabilizer, a dispersant, a flame retardant, a lubricant, an antistatic agent, a surfactant, a plasticizer and the like.

[Effect] According to the optical information recording medium of the present invention configured as described above, it is possible to obtain a recording medium having high stability against heat and light, excellent storage stability, and little reproduction deterioration. Further, even if a long wavelength laser (semiconductor laser) is used, recording can be performed with high sensitivity, pits can be formed in a good shape, and high C / N can be obtained.

[Examples] The present invention is further described below with reference to Examples along with Comparative Examples, but the present invention is not limited to these Examples.

Example 1 A dye of the following general formula and the above-exemplified compound A were mixed in a weight ratio of 100: 15
Then, the solution dissolved in 1,2-dichloroethane was spin-coated on a polymethylmethacrylate substrate to form a recording layer having a thickness of about 500Å to prepare a recording medium.

Example 2 Instead of the compound A in Example 1, the above-mentioned exemplified compound C
Was used and a recording medium was prepared in the same manner as in Example 1 except that the weight ratio of the dye to the compound C was 100: 20.

Example 3 A recording medium was prepared in the same manner as in Example 1 except that the dye used in Example 1 was replaced with the dye of the following general formula and the weight ratio of the dye to the compound A was 100: 20.

Example 4 Instead of the compound A in Example 3, the above-exemplified compound H
Was used and a recording medium was prepared in the same manner as in Example 3 except that the weight ratio of the dye to the compound H was 100: 30.

Example 5 Colcoat 103 on a polymethylmethacrylate substrate
X (manufactured by Nippon Corcoat Co., Ltd.) A solution prepared by dissolving Exemplified Compound D at a weight ratio of 100: 2 was spin-coated to a thickness of about 1 μm.
To form an undercoat layer. A solution of only the dye used in Example 1 was applied onto the undercoat layer to form a recording layer having a thickness of about 500 Å to prepare a recording medium.

Example 6 A solution containing only the dye of Example 1 was applied onto a polymethylmethacrylate substrate to form a recording layer having a thickness of about 500Å. On top of that, Poval (PVA205-Kuraray Co., Ltd.)
Preparation] and the above-exemplified compound A at a weight ratio of 1: 1 in a methanol / water (1/2) mixed solvent, sufficiently dispersed and then coated to a thickness of about 3
A protective layer having a thickness of μm was formed to prepare a recording medium.

Example 7 A recording medium was prepared in the same manner as in Example 1 except that the dye used in Example 1 was replaced with a dye of the following general formula and the weight ratio of the dye to the compound A was 100: 15.

Example 8 A recording medium was produced in the same manner as in Example 1 except that the dye used in Example 1 was replaced with the dye of the following general formula.

Comparative Example 1 Example 1 except that only the dye was used in Example 1.
A recording medium was prepared in the same manner as in.

Comparative Example 2 Example 3 except that only the dye was used in Example 3.
A recording medium was prepared in the same manner as in.

Comparative Example 3 A recording medium was produced in the same manner as in Example 6 except that the protective layer was formed using only Poval in Example 6.

The wavelength of each recording medium prepared in the above-mentioned examples and comparative examples
Using a semiconductor laser beam of 790 nm, information is written and reproduced from the substrate side at a recording frequency of 0.7 MHz and a linear velocity of 1.2 m / sec, and the reproduced waveform is spectrally analyzed (scanning filter, bandwidth 30 KHz) to obtain C / N. It was measured. Furthermore, the same recording medium was irradiated with 1 kW of tungsten light from a distance of 20 cm for 25 hours, and a reflectance and C / N were measured after a reproduction deterioration rate experiment was performed. The reflectance was measured from the substrate side. The results are summarized in the table below.

Claims (2)

[Claims] 1. An optical information recording medium comprising an organic dye thin film recording layer containing a polymethine dye as a main component on a substrate directly or via an undercoat layer, and at least one of the undercoat layer and the recording layer. General formula in two layers (In the formula, Z represents an atomic group necessary for completing a substituted or unsubstituted carbocyclic ketone, and an aromatic ring may be fused to the carbocyclic ring, and R ₁ and R ₂ are the same or not. Or may be different and each represents a substituted or unsubstituted alkyl group or a substituted or unsubstituted aryl group, X represents an acid anion, m represents 0, 1 or 2 and A is (N represents 1 or 2) or (When m = 2), R ₃ represents a hydrogen atom, an alkyl group or an alkoxy group. ) An optical information recording medium comprising a compound represented by: 2. An optical information recording medium in which an organic dye thin film recording layer containing a polymethylene dye as a main component is provided on a substrate directly or via an undercoating layer, and a protective layer is further provided on the recording layer. General formula for at least one of the recording layer, recording layer and protective layer (In the formula, Z represents an atomic group necessary for completing a substituted or unsubstituted carbocyclic ketone, and an aromatic ring may be fused to the carbocyclic ring, and R ₁ and R ₂ are the same or not. Or may be different and each represents a substituted or unsubstituted alkyl group or a substituted or unsubstituted aryl group, X represents an acid anion, m represents 0, 1 or 2 and A is (N represents 1 or 2) or (When m = 2), R ₃ represents a hydrogen atom, an alkyl group or an alkoxy group. ) An optical information recording medium comprising a compound represented by: