JP3032588B2 - Optical information recording medium - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical information recording medium.

2. Description of the Related Art The following types of optical information recording media have been proposed. (A) A recording layer using a low melting point metal thin film (b) A recording layer having a two-layer structure of a reflective film and an organic light absorbing layer (c) An organic dye film having a high reflectance was used for the recording layer The recording medium of the type (a) has a recording layer composed of a thin film mainly composed of a low-melting-point metal such as Te, and utilizes a perforated type and a reflectance change accompanying a crystal-amorphous phase transition. There is a phase change type. This type of recording medium has poor storage stability, the perforated type has a low resolution and the recording density does not increase, and the phase change type has the disadvantage that the manufacturing conditions are difficult and the cost is high. In the recording medium of the type (b), an organic light absorbing layer is coated on a metal reflective film.
The organic light-absorbing layer is irradiated with laser light to form a depression and record information. This type of recording medium has a two-layer structure in which a recording layer has an organic absorption layer laminated on a metal reflection film, which is troublesome to manufacture, and has a metal reflection layer that is not deformed or deteriorated by light or heat. Therefore, there is a disadvantage that recording / reproduction from the substrate side is difficult.

[0002] The recording medium of the type (c) has an organic dye thin film having a high reflectance provided as a recording layer on a substrate. Organic dye thin film has high melting point, high decomposition temperature and low thermal conductivity, so high sensitivity, high C / N ratio and high reliability can be expected.
In addition, since film formation can be performed by coating, there are advantages that mass productivity is good and cost reduction can be expected. Conventionally, optical disks have been characterized by large-capacity, high-density recording. However, in order to further increase the recording density, the optical disk has reached the limit as far as a current semiconductor laser is used. This is because the recording density of the optical disc is largely controlled by the wavelength of the light used for recording and reproduction, and the recording and reproduction of recording pits of about the same level as the recording and reproduction wavelength is limited. The wavelength of the semiconductor laser of the recording / reproducing light source currently used in the world is about 800.
nm, the minimum recording pit is about 0.8 μm. In order to further reduce the minimum recording pit, the recording / reproducing wavelength must be shortened. In recent years, the development of short wavelength lasers used in these has been actively pursued, and the miniaturization of gas lasers and the development of blue lasers or semiconductor lasers themselves by combining semiconductor lasers with nonlinear optical elements have been developed. Shorter wavelengths are being measured. Light source of such a short wavelength,
For example, if light having a wavelength of 700 to 500 nm is used, the recording pit can be made smaller, and the recording density can be reduced to about 1.
It becomes possible to make it 3 to 2.5 times or more. The present invention
It is an object of the present invention to provide an optical information recording medium used for a large-capacity optical memory system using these short wavelength light sources.

[0003]

Means for Solving the Problems As a result of intensive studies, the present inventors have found that it is effective to include a specific compound in the recording layer, and have reached the present invention. That is,
The present invention relates to an optical information recording medium comprising a recording layer provided directly or via an undercoat layer on a substrate, and further comprising a protective layer if necessary. 2]
(Excluding metal chelate compounds)
( 1 ) an optical information recording medium comprising at least one of the following: The above formula [1] used in the present invention,
Preferred compounds of the formula 2 are shown below.

Embedded image

[0004]

[Table 1]

[0005]

[Table 2] Table 1 continued

Next, other components used in the optical information recording medium of the present invention will be described. Substrate A necessary characteristic of the substrate is that it must be transparent to the laser light used only when recording and reproduction are performed from the substrate side, and need not be transparent when it is performed from the recording layer side. As the substrate material, for example, a plastic such as polyester, acrylic resin, polyamide, polycarbonate resin, polyolefin resin, phenol resin, epoxy resin, polyimide, glass, ceramic or metal can be used. Incidentally, a guide groove or guide pit for tracking, and a pre-format for an address signal or the like may be formed on the surface of the substrate. Undercoating layer The undercoating layer comprises (a) an improvement in adhesiveness, (b) a barrier against water or gas, (c) an improvement in storage stability of the recording layer and (d) an improvement in reflectance, and (e) a solvent. Protection of the board from
(F) Used for the purpose of forming guide grooves, guide pits, pre-formats, and the like. For the purpose of (a), various polymer materials such as ionomer resins, polyamide resins, vinyl resins, natural resins, natural polymers, silicones, liquid rubbers, and silane coupling agents are used for the purpose of (a). For the purposes of (b) and (c), besides the above-mentioned polymer material, an inorganic compound such as Si
O ₂ , MgF ₂ , SiO, TiO ₂ , ZnO, TiN, S
metals or metalloids such as iN, for example Zn, Cu, S, N
i, Cr, Ge, Se, Au, Ag, Al and the like can be used. For the purpose of (d), a metal such as Al, Ag, etc., or an organic thin film having a metallic luster,
For example, a methine dye, a xanthene dye, or the like can be used. For the purposes (e) and (f), an ultraviolet curable resin, a thermosetting resin, a thermoplastic resin, or the like can be used.

Protective Layer The protective layer (a) protects the light reflecting / absorbing layer from scratches, dust, dirt and the like. It is used for the purpose of (b) improving the storage stability of the light reflection / absorption layer, and (c) improving the reflectance. For these purposes, the materials shown in the undercoat layer can be used. As inorganic materials, SiO, Si
O _{2 and the} like can also be used, and as an organic material, polymethyl acrylate, polycarbonate, epoxy resin,
Polystyrene, polyester resin, vinyl resin, cellulose, aliphatic hydrocarbon resin, aromatic hydrocarbon resin,
Natural rubber, stinbutadiene resin, chloroprene rubber,
A heat-softening and heat-melting resin such as wax, alkyd resin, drying oil and rosin can also be used. In the present invention, 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 as in the case of the recording layer. The optical information recording medium of the present invention is basically constituted by providing a recording layer made of an organic dye containing the compound in the claims as a main component on a substrate. An undercoat layer may be provided between the layers, or a protective layer may be provided on the recording layer. Further, an air-sandwich structure in which the pair of recording media thus constructed is sealed with another substrate with a recording layer on the inner side through a space may be used, or a close-contact sandwich bonded via a protective layer ( (Lamination) structure. The thickness of the recording layer is 100 to 10 μm, preferably 200 to 2 μm. As a method for forming the recording layer, in addition to vapor deposition, CVD, and sputtering, a solvent coating method, for example, immersion coating, spray coating, spinner coating, blade coating, or roast coating can be used. Lacoating, curtain coating and the like can be used.

[0008]

[Embodiment 1] Acrylic photopolymer on a 1.2 mm thick PMMA substrate with a pitch of 1.3 μm
Compound No. 1 was placed on a substrate provided with a linear guide groove.
1 was formed into a recording layer having a thickness of 900 ° by vacuum evaporation, and this was sealed in an air-sandwich type to obtain an optical information recording medium. At this time, the maximum absorption wavelength of the film was 695 nm. The optical information recording medium has an oscillation wavelength of 632.8 nm.
The recording was carried out at 5.0 mw power under the following conditions by using He-Ne laser light. Linear velocity 2.1 m / sec Recording frequency 1.6 MHz Pickup lens NA: 0.5 The apparatus using the above recording position for recording has a power of 0.2 mW.
When the reproduction was performed using continuous light, a C / N ratio of 47 dB was obtained at a scanning bandwidth of 30 kHz. Embodiment 2. FIG. In Example 1, the substrate was changed to a polycarbonate injection molded substrate. 2, and an optical information recording medium was obtained in the same manner. The maximum absorption wavelength of the film at this time is 5
It was 89 nm, and the C / N ratio and 45 dB were obtained. Embodiment 3 FIG. In Example 2, the compound was designated as Compound Example No. As No. 14, an optical information recording medium was similarly obtained. The maximum absorption wavelength of the film at this time is 595 nm, and the C / N ratio is 46 dB.
I got

[0009]

As described above, the optical information recording medium of the present invention has an extremely large recording density of 1.3 to 2.5 times or more that of the conventional optical information recording medium, and is useful as a recording material for a short wavelength semiconductor laser. It is.

Claims (2)

(57) [Claims] 1. An optical information recording medium comprising a recording layer provided directly or via an undercoat layer on a substrate, and a protective layer as necessary, wherein the recording layer has the following [Chem. 1], [Chem. (Wherein a metal chelate compound is
The optical information recording medium, characterized in that the excluded) comprising at least one. Embedded image Embedded image (Chemical Formula 1], Oite to the reduction 2], R ₁ to R ₈ may be different even in the same, hydrogen, hydroxyl, halogen,
A substituted or unsubstituted alkyl group, alkylamino group, alkoxy group, amino group, nitro group, acyl group, aryl group, aralkyl group, morpholino group, or a part condensable with another aromatic ring in the above general formula May be condensed with another aromatic ring) 2. A high-density recording method for recording on the optical information recording medium according to claim 1, using a laser beam having a wavelength between 500 and 700 nm.