JP2951961B2 - Optical recording medium - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an optical recording medium for optically recording and reproducing information.

[Conventional technology]

The optical recording medium has a structure in which an optical recording layer is formed on an optical recording medium substrate, and the optical recording layer is irradiated with a laser beam or the like to record and reproduce information by light.

Recording of information on the optical recording medium is performed by irradiating a laser beam to form pits (holes) in the optical recording layer or cause other physical changes. The reproduction of information is performed by utilizing the optical change caused by the change of the optical recording layer as described above.

Such an optical recording medium has a high areal recording density and is useful for recording a large amount of data.

The manufacturing method of the optical recording medium is roughly classified into a vapor deposition method and a coating method. An optical recording medium having an inorganic recording film can be manufactured only by a vapor deposition method, whereas an optical recording medium having an organic recording film can be manufactured by a coating method.
In the vapor deposition method, a large-scale vacuum device is required for the manufacturing process. However, the coating method does not require such a device. Therefore, an organic optical recording medium is more advantageous in productivity.

The performance required for such a dye for an optical recording medium includes high reflectivity, excellent sensitivity, and excellent durability.

One of the dyes satisfying such performance is, for example, a polymethine dye. However, although this dye is extremely excellent in reflectance and sensitivity, it has a drawback that it is inferior in durability such as reproduction light stability (stability to read laser) and heat and moisture resistance.

Conventionally, in order to solve such a drawback, (1) the medium structure has a structure in which the recording film does not come into contact with the outside air. (2) a method of covering a defect in a portion other than the recording film, such as reducing the output of a reading laser beam, and (3).
Methods such as designing the molecular structure to have high durability have been actually performed.

However, in such a method, for example, the methods (1) and (2) impose a burden on a medium and a reading device, and the method (3) does not provide a medium having good reflectance and sensitivity. Alternatively, only those having poor solvent solubility required for forming a recording film were obtained.

[Basic idea]

The present invention has been studied to improve the poor performance, for example, the durability while maintaining the excellent performance, for example, the reflectance and the sensitivity of the organic dye. It has been found that by mixing an organic dye with an organic dye, it is possible to improve durability such as heat and moisture resistance and reproduction light stability while maintaining excellent performance such as reflectance and sensitivity.

This mechanism is probably due to the fact that the water repellency of the organic polysiloxane resin after curing increases, so that the affinity between the dye and water is inhibited by forming a structure that encapsulates the organic dye in the organic polysiloxane resin. In addition, the durability of the dye to water is increased. Since the thermal conductivity of the organic polysiloxane is larger than that of the dye, heat storage of the signal reading laser hardly occurs, and as a result, the stability of reproduction light is improved. By mixing the dye with the organic polysiloxane, the concentration of the dye per unit volume is reduced, but the dye is dispersed in the organic polysiloxane so as to break the association between the dyes, and the absorbance of each dye molecule due to the association is reduced. The decrease is small, and as a result, the amount of heat absorbed per unit volume of the recording film does not decrease so much. As a result, sensitivity and reflectance, which are excellent performances, can be maintained.

[Disclosure of the Invention]

That is, the present invention relates to an optical recording medium capable of recording and reading signals by irradiating a laser beam from a transparent substrate side, comprising a transparent optical recording medium substrate and an organic polysiloxane provided on the substrate. The present invention relates to an optical recording medium substantially composed of an optical recording layer made of a mixture of a resin and a dye.

The substrate resin used in the present invention is preferably a resin that transmits light for recording and reading signals. It is desirable that the light transmittance is 85% or more and the optical anisotropy is small. For example, an acrylic resin, a polycarbonate resin, a polyester resin, a polyamide resin, a vinyl chloride resin, a polyvinyl ester resin, a polyolefin resin, a polystyrene resin, a polyphenylene oxide resin, or a mixed resin of these resins can be used. Among them, acrylic resin, polycarbonate resin, polyolefin resin or polystyrene resin and polycarbonate resin, and mixed resin of polystyrene resin and polyphenylene oxide resin are preferable in terms of mechanical strength, hygroscopicity, and economical efficiency of the substrate. And polycarbonate resin are more preferred.

The method for molding the substrate for an optical recording medium of the present invention may be injection molding, 2P method, or extrusion molding, but an injection molded substrate is desirable from the viewpoint of mass productivity. Further, for the purpose of improving the solvent resistance and the like, the surface may be subjected to a treatment such as coating.

The shape of the substrate of the present invention may be plate-like, film-like, circular or card-like. The recording film is formed by dissolving a mixture of an organic dye and an organic polysiloxane resin in an organic solvent, and spin-coating the substrate on the substrate. This mixing ratio can be from 0.05 to 5.0 parts by weight of the organic polysiloxane resin to 1 part by weight of the dye, but is preferably from 0.2 to 2.0 parts by weight, more preferably from 0.3 to 1.5 parts by weight. Generally, the higher the content of the organic polysiloxane resin, the better the durability, but the reflectance and sensitivity are slightly reduced. Depending on the nature of the optical recording medium, it is possible to determine which one to focus on.

Further, it is desirable that the film is formed to have a thickness of 10 to 200 nm, more preferably 50 to 150 nm.

Examples of the organic dye used in the present invention include a polymethine dye, a dithiol metal complex dye, an aromatic or unsaturated aliphatic diamine metal complex dye, a squarylium dye, an azulene dye, a naphthoquinone dye, and an anthraquinone dye. Dyes, macrocyclic azaannulene dyes such as porphyrin, phthalocyanine and naphthalocyanine, quinonoid dyes, triallylmethane dyes and the like can also be used. Each of these may be used alone or in combination of two or more.

Examples of the organic polysiloxane resin used in the present invention include a bifunctional silane represented by R ₁ R ₂ Si (OR ₃ ) _2-n (X) _n and R ₄ Si (OR ₅ ) _3-n (X ) Trifunctional silane represented by m or tetrafunctional silane represented by Si (OR ₆ ) _h (X) _4-h (R ₁ , R ₂ , R ₃ , R ₄ , R ₅ , R ₆ are alkyl groups Or an aryl group, X represents a hydroxyl group or a halogen, n represents 0, 1, or 2, m represents 0, 1, 2, or 3, and h represents 0, 1, 2, 3,
Or 4) is condensed, and specific examples of R ₁ , R ₂ , R ₃ , R ₄ , R ₅ and R ₆ include:
Examples include an alkyl group such as a methyl group, an ethyl group, a propyl group, a butyl group, a hexyl group, an octyl group and a cyclohexyl group, and an aryl group such as a phenyl group, a methylphenyl group, a naphthyl group, and a benzyl group. Further, specific examples of halogen include chlorine, bromine and iodine. The types of these substituents in one molecule may be the same or different. Furthermore, these bifunctional, trifunctional silane and tetrafunctional silane may be used alone or in combination of two or more.

As a solvent for applying the mixture of the organic dye and the organic polysiloxane resin, for example, methanol, ethanol,
Alcohol solvents such as propyl alcohol, butyl alcohol, pentyl alcohol and hexyl alcohol; glycol ether solvents such as ethylene glycol monomethyl ether and ethylene glycol monoethyl ether; aromatics such as toluene and xylene; ketones; esters; and chlorine Hydrocarbon solvents, fluorinated hydrocarbon solvents, diethyl ether, dipropyl ether, dibutyl ether, dihexyl ether, ether solvents such as ethylene glycol dimethyl ether, glycol ethers such as ethylene glycol monomethyl ether and ethylene glycol monoethyl ether Examples of the solvent include a solvent and a solvent containing water as a main component. These solvents may be used alone or in combination of two or more. After applying the mixture of the dye and the organic polysiloxane resin to the substrate, if necessary, forced drying may be performed to dry the recording film or to accelerate the crosslinking reaction of the organic polysiloxane resin.

[Preferred embodiment for carrying out the invention]

Hereinafter, the present invention will be described specifically with reference to examples, but embodiments of the present invention are not limited thereto.

Example 1 A cyanine dye (having the following structural formula) was applied to an injection-molded polycarbonate resin substrate having a spiral guide groove having a thickness of 1.2 mm and a diameter of 130 mm. 2% by weight methanol solution and a 1% by weight methanol solution of an organic polysiloxane resin having an average molecular weight of about 500 obtained by precondensing 30% by weight of diphenyl-diethoxysilane and 70% by weight of phenyl-triethoxysilane in advance. After dripping, rotate at a speed of 2000 rpm for 10 seconds,
An optical recording medium was formed by forming an optical recording layer.

This optical recording medium is measured at a wavelength of 780 nm, a pulse width of 500 nm,
When the sensitivity was measured at a writing duty of 1: 1 and a linear velocity of 5.5 m / s, the C / N was 50 dB or more at 5 mw or more, indicating good sensitivity. Further, when the reflectance of this optical recording medium was measured, a reflectance of 24% was obtained at a measurement wavelength of 780 nm. Even when this optical recording medium was left at 60 ° C. and 90% RH for 3000 hours, the change in reflectance was −5%. Furthermore, when the reproduction light stability of this optical recording medium was measured, it was 0.5 mW at a measurement wavelength of 780 nm,
No change in C / N was observed at 1 million strokes at a linear velocity of 5.5 m / s.

Example 2 Injection-molded polycarbonate resin substrate having a spiral guide groove having a thickness of 1.2 mm and a diameter of 130 mm was coated with a 1.5% by weight methanol solution of a cyanine dye (used in Example 1) and diphenyl-diethoxysilane. 30% by weight
Of an organic polysiloxane resin having an average molecular weight of about 500, which was precondensed in advance with 70% by weight of phenyl-triethoxysilane.
After dropping a mixture of a 1.5 wt% methanol solution, the mixture was rotated at a speed of 2000 rpm for 10 seconds to form an optical recording layer to produce an optical recording medium.

This optical recording medium is measured at a wavelength of 780 nm, a pulse width of 500 nm,
When the sensitivity was measured at a writing duty of 1: 1 and a linear velocity of 5.5 m / s, the C / N was 50 dB or more at 6.5 mW or more, indicating good sensitivity. Further, when the reflectance of the optical recording medium was measured, a reflectance of 19% was obtained at a measurement wavelength of 780 nm. Even when this optical recording medium was left at 60 ° C. and 90% RH for 3000 hours, the change in reflectance was −1%. Furthermore, when the reproduction light stability of this optical recording medium was measured, it was 0.7 m at a measurement wavelength of 780 nm.
W, C / N did not change at 1 million strokes at a linear velocity of 5.5 m / s.

Comparative Example 1 A 3.5% by weight methanol solution of a cyanine dye (used in Example 1) was dropped onto an injection-molded polycarbonate resin substrate having a spiral guide groove having a thickness of 1.2 mm and a diameter of 130 mm. By rotating at a speed for 10 seconds, an optical recording layer was formed to produce an optical recording medium.

This optical recording medium is measured at a wavelength of 780 nm, a pulse width of 500 nm,
When the sensitivity was measured at a write duty of 1: 1 and a linear velocity of 5.5 m / s, the C / N was 50 dB or more at 4.5 mW or more, indicating good sensitivity. Further, when the reflectance of the optical recording medium was measured, a reflectance of 25% was obtained at a measurement wavelength of 780 nm. When this optical recording medium was left at 60 ° C. and 90% RH for 3000 hours, the change in reflectance was −15%. Furthermore, when the reproduction light stability of this optical recording medium was measured, it was 0.5 m at a measurement wavelength of 780 nm.
C / N decreased by -30dB at 1M times at W and linear velocity 5.5m / s.

Example 3 Injection-molded polycarbonate resin substrate having a spiral guide groove with a thickness of 1.2 mm and a diameter of 130 mm was coated with a 5 wt. Methanol solution of a cyanine dye (used in Example 1) and diphenyl-diethoxysilane 30. % Of phenyl-triethoxysilane and 70% by weight of phenyl-triethoxysilane in advance, and a mixture of a 2.5% by weight methanol solution of an organic polysiloxane resin having an average molecular weight of about 500 was added dropwise.
By rotating at a speed of 00 rpm for 10 seconds, an optical recording layer was formed to produce an optical recording medium.

This optical recording medium is measured at a wavelength of 780 nm, a pulse width of 500 nm,
When the sensitivity was measured at a write duty of 1: 1 and a linear velocity of 5.5 m / s, the C / N was 40 dB or more at 12.0 mW or more. further,
When the reflectance of this optical recording medium was measured, the measurement wavelength was 780n.
A reflectance of 8% was obtained at m. Use this optical recording medium at 60 ° C, 90% R
When left at H for 3000 hours, the change in reflectance was 0%. Furthermore, when the reproduction light stability of this optical recording medium was measured, 0.8 mW at a measurement wavelength of 780 nm and C at 1 million times at a linear velocity of 5.5 m / s.
There was no decrease in / N.

〔The invention's effect〕

The optical recording medium of the present invention has excellent performance by mixing an organic dye with an organic polysiloxane resin, and improves durability such as heat resistance, humidity resistance and reproduction light stability while maintaining reflectance and sensitivity. did it.

────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Masao Okazawa 138-1 Machibo, Mobara-shi, Chiba Prefecture (72) Inventor Tadahiko Mizuka 287-1, Mutsuno, Mobara-shi, Chiba Prefecture (72) Inventor Hiromi Inagaki 2791, Mutsuno, Mobara-shi, Chiba Prefecture -1 (56) References JP-A-63-102987 (JP, A) JP-A-2-2067 (JP, A) JP-A-64-38744 (JP, A) JP-A-63-145086 (JP, A) (58) Fields surveyed (Int. Cl. ⁶ , DB name) B41M 5/26

Claims (1)

(57) [Claims] The material of an optical recording layer on an optical recording medium substrate is as follows:
An optical recording medium comprising a mixture of an organic polysiloxane resin and an organic dye.