JP3293293B2 - Optical recording material - 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 recording medium on which information can be written and read by a laser beam. Especially for high density optical recording, 6
The present invention relates to an optical recording medium capable of recording and reproducing with a laser beam having a wavelength of 50 to 700 nm.

[0002]

2. Description of the Related Art Conventionally, as a medium for recording information using a laser beam, a write-once optical recording medium using a low-melting-point metal-based or organic dye-based material for a recording layer has been put to practical use. In a conventional write-once optical recording medium that has been put into practical use, the wavelength of a semiconductor laser used for recording and reproduction is 780 to 830 nm. In recent years, research on high-density optical recording has been actively carried out, and higher densification by reducing the size of recording pits has been promoted. As a method therefor, there are methods of shortening the wavelength of a semiconductor laser used for recording and reproduction, reducing the beam diameter of the aperture, and increasing the density by reducing the track pitch. In response to these high-density measures, the development of semiconductor lasers has
Pickups of about nm are being put to practical use. Also,
With the advance of molding technology, the track pitch can be reduced to 1.6μ.
It has become possible to reduce the width from m to about 1.1 μm.

However, the conventional organic dye-based recording material used for the recording layer of the write-once optical recording medium is 650-700.
The sensitivity was low due to insufficient absorption near nm. The low-melting-point metal-based recording material has absorption near 650 to 700 nm and has sensitivity, but has high thermal conductivity, so that large pits are formed, and it is difficult to form clear fine pits. In terms of characteristics, the possibility of an organic dye-based recording material having low thermal conductivity and excellent formation of fine pits is high.
There was no recording material having absorption near 700 nm and having sufficient recording sensitivity.

[0004]

The present inventors have conducted intensive studies with a focus on organic dyes, particularly phthalocyanines, which have high stability. As a result, they have a large absorption around 650 to 700 nm, and are suitable for high-speed recording and fine pit formation. We have developed a recording material that is fully compatible.

[0005]

The present invention is an optical recording material for high-density digital recording with a laser wavelength of 650 to 700 nm, comprising a phthalocyanine compound represented by the following structural formula [1]. Structural formula [1]

Embedded image [N represents 1 or 2. ]

The phthalocyanine compound represented by the structural formula [1] can be produced by the following method. That is, a hydroxy form of the phthalocyanine compound represented by the structural formula [2] can be produced by a conventional method using phthalic acid, phthalic anhydride, phthalonitrile or 1.3-diiminoisoindrain and aluminum chloride as starting materials.

[0007] Structural formula [2]

Embedded image Next, by reacting N-hydroxymethylphthalimide with the obtained hydroxy compound of the phthalocyanine compound represented by the structural formula [2], the phthalocyanine compound represented by the structural formula [3] can be produced. The phthalimidomethyl group may be substituted on the benzene ring of the phthalocyanine skeleton or coordinated to the central metal aluminum. Structural formula [3]

Embedded image

Next, the resulting phthalocyanine compound represented by the structural formula [3] is reacted with diphenylchlorophosphine to produce the phthalocyanine compound represented by the structural formula [1]. Structural formula [1]

Embedded image

The optical recording medium using the optical recording material of the present invention has a laminated structure in which a recording layer of the phthalocyanine compound of the present invention is provided on a transparent substrate, and a buffer layer is provided on the recording layer if necessary. is there. In the recording layer using the phthalocyanine compound represented by the structural formula [1] in the present invention, the oxygen quencher is used for the purpose of further improving the stability of the recording layer such as light resistance and environmental resistance and the stability of repeated reproduction. Alternatively, an additive such as an ultraviolet absorber may be added. The recording layer can be formed by a dry process, for example, a vacuum deposition method or a sputtering method.
For example, spin coating, dipping, spraying, roll coating, or LB (Angmuir Blodgett) is also possible. The phthalocyanine compound of the present invention is a general-purpose organic solvent, for example, alcohol,
It is dissolved in a ketone, cellosolve, hydrocarbon, halogenated hydrocarbon, chlorofluorocarbon or the like at a concentration of about 10 to 100 mg / ml, so that a film is formed by spin coating from the viewpoint of productivity and uniformity of the recording layer. Is most preferred.

When forming a film by such a so-called coating method, a polymer binder may be added as necessary. Acrylic resin, polycarbonate resin, polyester resin, polyamide resin,
Examples include, but are not limited to, vinyl chloride resins, vinyl acetate resins, nitrocellulose, phenol resins, and the like. The mixing ratio of the polymer binder is not particularly limited, but may be 30 to phthalocyanine-based compound.
% Or less is preferable. Regarding the thickness of the recording layer of the present invention,
Because the recording layer differs depending on the combination of the phthalocyanine compound of the present invention and other additives as the recording layer, there is no particular limitation, but the average film thickness in consideration of the unevenness due to guide grooves and the like formed on the substrate. The thickness is preferably from 300 to 3000 Å, and more preferably from 500 to 1500 Å.

In the configuration of the optical recording medium to which the optical recording material of the present invention is applied, a buffer layer that can be used is preferably a material that can absorb the deformation of the recording layer caused by the irradiation of the recording laser. A polymer material is suitable in terms of film forming properties and cost, and examples thereof include, but are not limited to, urethane resins, silicone resins, and low molecular weight acrylic resins. Examples of a method for forming such a buffer layer include a wet process, for example, bar coating and spin coating, but are not limited thereto. The thickness of the buffer layer of the present invention is not particularly limited. Further, it is also possible to add an adhesive function to this buffer layer and to bond two recording media with the adhesive buffer layer interposed therebetween, thereby forming an optical recording medium for double-sided recording. The transparent substrate used in the present invention preferably has a light transmittance of preferably 85% or more and a small optical anisotropy for writing and reading signals. For example, glass or acrylic resin, polycarbonate resin, polyester resin, polyamide resin, vinyl chloride resin, polyvinyl ester resin, polystyrene resin, polyolefin resin (for example, poly-4-methylpentene, etc.), polyethersulfone resin, etc. A substrate using a thermosetting resin such as a thermoplastic resin, an epoxy resin, or an allyl resin may be used. Further, those obtained by depositing SiO2 or the like on these substrates may be used. Among these, the above-mentioned thermoplastic resins are preferable in terms of ease of molding, ease of providing guide grooves, address signals, and the like.

In the present invention, the thickness of these transparent substrates is not particularly limited, and may be plate-like or film-like. The shape may be circular or card-like, and its size is not particularly limited. That is, the present invention is not limited to a disk-shaped general optical disk, but may be an optical card, a tape-shaped or sheet-shaped recording medium. Also, the transparent substrate of the present invention usually has guide grooves for position control at the time of recording and reading, and irregularities for preformatting such as address signals and various marks, and these irregularities are described above. When molding (injection molding, compression molding) such a thermoplastic resin, a method of applying the same using a stamper or the like is preferable, but it can also be performed by a so-called 2P method using a photopolymer resin. The shape of the guide groove of the present invention is not particularly limited, and may be short, trapezoidal, or U-shaped. The optimum values of the dimensions of the guide grooves vary depending on the type and combination of the materials used for the recording layer, but the average groove width (width at a position の of the groove depth) is 0.3 to 0.2 mm. 6 microns, groove depth 500-250
A range of 0 Å is preferred.

Further, chemical deterioration of the medium (eg, oxidation,
A protective layer may be provided on the laser light incident surface of the transparent substrate for the purpose of preventing water absorption or the like and physical deterioration (scratch, shear, etc.). As a material for the protective layer, a method of applying a vapor-deposited or sputtered film of a transparent inorganic material such as SiO2 or a UV-curable resin, applying by spin coating, and curing by UV irradiation is preferable, but is not limited thereto. is not. Regarding the optimum thickness of the protective layer, when the thickness is thin, the effect of protection is reduced, and when the thickness is thick, shrinkage during curing of the resin causes deterioration of mechanical characteristics such as warpage of the medium. It is preferable to form a film in the range of microns. Further, for the purpose of imparting functions other than the protective layer, for example, antireflection, antistatic, moistureproofing, etc., a low-refractive-index material, a fluororesin or a conductive resin, etc., on the laser incident surface side of the transparent substrate as well as the protective layer and recording It may be provided on a layer or a reflective layer. Typical optical recording media to which the present invention can be applied include a DRAW type optical disk for document files, a write-once type LD, and the like, but are not limited thereto. When the optical recording medium of the present invention is formed of a single recording layer, it may have a two-layer bonding structure such as an air sandwich.

[0014]

EXAMPLES The present invention will be described specifically with reference to the following examples, but the present invention is not limited to the following examples. Example 1 1.20 mm thick with 700 angstrom deep, 0.4 micron wide, 1.1 micron pitch guide grooves
On a polycarbonate substrate having an outer diameter of 200 mm and an inner diameter of 30 mm, a phthalocyanine-based compound represented by the structural formula [1] was dissolved in ethoxyethanol at a concentration of 20 mg / ml.
The coating liquid was adjusted by performing micron filtering, and a film was formed to a thickness of 800 angstroms by a spin coater using the coating liquid to prepare a single-layer optical disk. The maximum absorption wavelength of the optical disk thus created is 685 n
m and the reflectance at 680 was 32%. Using the optical disk created in this way, the wavelength 680 nm,
N. A. = 8.0 using a semiconductor laser of 0.55
When a signal having a frequency of 40 MHz was recorded at mW and a linear velocity of 13 m / sec, the C / N ratio became 52 dB, and recording of reproducible signal quality was performed.

Example 2 A laminated optical disk was prepared by providing a fluororesin-based buffer layer on the recording layer of the single-layer optical disk prepared in Example 1. When the optical disk thus produced was recorded in the same manner as in Example 1, the C / N ratio was 42 dB, and reproduction was sufficiently possible.

As is clear from the examples, when the phthalocyanine compound of the present invention is applied to the recording layer, the wavelength 68
It has become possible to obtain an optical recording medium applicable to high-density digital recording with a laser of 0 nm.

Claims (1)

(57) [Claims] 1. A laser wavelength of 650 to 700 nm comprising a phthalocyanine compound represented by the following structural formula [1]:
Optical recording material for high-density digital recording. Structural formula [1] [N represents 1 or 2. ]