JPH11144311A - Optical recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To decrease jitters by adjusting the shape in the peripheral parts of its accompanying a temp. rise at the time of recording of an optical recording medium having a recording layer contg. at least org. dyestuffs. SOLUTION: The shapes of the peripheral parts of the pits are adjusted by forming a shape adjusting layer 3 by an org. compd. having plural adjacent heterocycles or condensed rings on the recording layer 2. Particularly porphyrazine dyestuffs and perylene dyestuffs are excellent as the org. compd. to be used for the shape adjusting layer 3, as these dyestuffs have high molecular flatness and excellent light resistance and preservable property. The recording layer 2 and the shape adjusting layer 3 are successively formed by a vapor deposition method, by which the effect of decreasing the jitters is increased and the stable characteristics are obtd.

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 recorded / reproduced by laser light, and more particularly to an optical recording medium containing at least an organic dye in a recording layer.

[0002]

2. Description of the Related Art In recent years, there are various types of optical recording media for recording and reproducing information by using a laser beam, in which a recording layer is formed on a substrate and a reflective layer and a protective layer are formed thereon. One is that the recording layer is formed by containing an organic dye. This is because when the recording layer is irradiated with laser light from the substrate side, the laser light is partially absorbed by the recording layer,
When the irradiated portion is locally heated and physical or chemical changes such as melting, evaporation, sublimation, or decomposition occur, pits are formed and information is recorded.

[0003] The pit information thus formed has optical characteristics that are different from those of the other portions, and is reproduced by irradiating a laser beam having a lower power than during recording.

[0004] Here, since the material used for the recording layer is an organic compound such as a dye, the shape of the peripheral portion of the pit changes, and irregularities are recognized.

[0005]

However, in the conventional structure described above, when a phthalocyanine dye having excellent light resistance is used as a recording layer material, irregular irregularities or rims are formed around the pits formed by recording. A deformation region called “waveform distortion” occurs, causing waveform distortion or deteriorating the tracking characteristics.

In particular, when long pits such as 11T are recorded, there has been a problem that, due to a rise in the temperature of the recording portion, a change in the shape of the pit peripheral portion occurs more conspicuously, and pit jitter increases.

An object of the present invention is to provide an optical recording medium which is excellent in light resistance, has good tracking characteristics, and has a reduced pit jitter even for long pits such as 11T.

[0008]

In order to solve the above-mentioned problems, an optical recording medium of the present invention is provided with a shape adjustment layer directly in contact with a recording layer, so that the shape of a pit peripheral portion during laser recording is improved. And the jitter can be reduced, and the shape adjusting layer contains a crystalline organic compound having a plurality of adjacent heterocyclic rings or condensed rings.

[0009]

In the optical recording medium according to the first aspect of the present invention, at least a recording layer containing an organic dye that transmits and absorbs laser light, a reflective layer, and a protective layer are sequentially formed on a substrate. And an optical recording medium provided with a shape adjusting layer made of an organic compound on the recording layer, wherein the organic compound is a compound having a structure containing a plurality of adjacent heterocycles or condensed rings. More than one type is used.

Here, when the shape adjusting layer is made of an organic compound, it is an organic compound similarly to the recording layer, so that the adhesion to the recording layer is relatively good. However, since there are micro gaps between the particles, the inside becomes moderately porous, so that the shape of the pit peripheral part at the time of recording can be changed only by following the deformation of the substrate or recording layer at the recording part to some extent. Not enough to adjust.

Therefore, the chemical structure of the organic compound of the shape adjusting layer has a plurality of adjacent condensed rings or hetero rings,
In addition, by having crystallinity, the planarity of the molecular structure is enhanced, and shape deformation can be suppressed. Further, since such an organic compound layer has a crystal grain boundary, the organic compound layer becomes appropriately porous at the grain boundary, and has an effect of absorbing and adjusting shape deformation of a pit peripheral portion at the time of recording. By the above effect, an optical recording medium with small jitter can be obtained.

In the optical recording medium according to the second aspect of the present invention, the organic compound constituting the shape adjusting layer of the optical recording medium according to the first aspect is a porphyrazine dye (a phthalocyanine dye, a naphthalocyanine dye, a porphyrin dye). Dyes, etc.) and perylene dyes are particularly suitable.

As a material constituting the shape adjusting layer, an organic compound having a plurality of adjacent fused or heterocyclic rings includes:
For example, there are anthraquinone-based dyes and triphenylmethane-based dyes. However, when these are left in a high-temperature and high-humidity environment, aggregation and the like are recognized, and characteristics are liable to be deteriorated.
On the other hand, the dye according to claim 2 is excellent in fastness such as heat resistance, light resistance, and storage stability, so that a stable layer can be formed, and an optical recording medium excellent in reliability can be obtained. .

Therefore, by containing a porphyrazine dye or a perylene dye as the shape adjusting layer, a jitter can be reduced and an optical recording medium with high reliability can be obtained.

In the optical recording medium according to a third aspect of the present invention, the organic dye constituting the recording layer of the optical recording medium according to the first or second aspect is coordinated with a tetravalent metal derivative represented by the following chemical formula (1). Phthalocyanine dye, whose central metal is Si,
Sn is particularly suitable.

In the formula (1), M is a tetravalent metal derivative. As the tetravalent metal, Si, Ge, Sn, T
i, V, etc., and the substituent Y introduced into this tetravalent metal
1 and Y2 are not particularly limited, but for example, well-known are a halogen atom, an oxygen atom, an alkyl group, an alkoxy group, an acyl group, a phenyl group, a phenoxy group and the like.

The substituents X ₁ to X ₁₆ are not particularly limited as long as they can be introduced into a phthalocyanine ring.
For example, hydrogen atom, halogen atom, substituted or unsubstituted alkyl group, substituted or unsubstituted alkoxy group, substituted or unsubstituted alkylthio group, substituted or unsubstituted aryl group, substituted or unsubstituted aryloxy group, substituted Alternatively, they may each independently have an unsubstituted arylthio group, nitro group, amino group or the like.

The halogen atom is fluorine, chlorine, bromine or iodine, and the substituted or unsubstituted alkyl group may be straight-chain or branched, saturated or unsaturated, for example, methyl, ethyl, n-propyl group, is
Examples include an o-propyl group, an n-butyl group, a tert-butyl group, and the like. Similarly, the substituted or unsubstituted alkoxy group may be linear or branched, saturated or unsaturated, and includes a methoxy group, an ethoxy group, a methoxymethyl group, and a propoxy group.

Similarly, the substituted or unsubstituted alkylthio group may be linear or branched, saturated or unsaturated, and examples thereof include a methylthio group, an ethylthio group and a tert-butylthio group. Examples of the substituted or unsubstituted aryl group include a phenyl group, a naphthyl group, and a pyrrole group. Representative examples of the substituted or unsubstituted aryloxy group include a phenoxy group.

Here, the phthalocyanine dye has a structure in which the phthalocyanine ring, which is the skeleton, has a plurality of adjacent heterocycles and condensed rings, so that the molecule has high planarity.
For this reason, as a shape adjusting layer formed on this recording layer,
Similarly, when the organic compound according to claim 1 or 2 is contained, which is a material having high planarity, the effect of adjusting the shape of the pit peripheral portion at the time of recording further increases due to the synergistic effect of both layers.

Particularly, a phthalocyanine-based dye having a tetravalent metal coordinated at the center thereof has a remarkable effect because molecules are likely to be present in a form relatively parallel to the substrate surface. Also,
Among the tetravalent metals, Si and Sn, when recorded with a laser beam having a wavelength of 790 nm, have a large light absorption at this wavelength, so that the thickness of the recording layer can be reduced. Since the shape change around the pit can be small, as a result, the adjustment effect of the shape adjustment layer on the recording layer is increased.

Therefore, by using a phthalocyanine dye having a tetravalent metal coordinated at the center thereof, preferably a phthalocyanine dye whose tetravalent metal is preferably Si or Sn, jitter can be reduced and stable. Optical recording medium can be obtained.

According to a fourth aspect of the present invention, in the optical recording medium, the recording layer and the shape adjusting layer are sequentially formed by a vapor deposition method.

The method of forming a thin film of an organic compound is roughly classified into a dry method such as vapor deposition and a wet method such as coating. In the wet method, a constituent organic compound is dissolved or dispersed in a solvent or the like. Therefore, the planarity of the molecule inherent in the compound is impaired. Further, when the recording layer and the shape adjusting layer are sequentially formed by the wet method, the outermost surface of the recording layer is eroded by the solvent used for coating the shape adjusting layer, and the characteristics are deteriorated.

On the other hand, since the dry process utilizes the sublimability of the compound itself, the film can be formed without impairing the planarity of the molecule and without eroding the outermost surface of the recording layer. Further, a compound having high molecular flatness has a high sublimation property and is suitable for a dry method. Among them, the vapor deposition method has a relatively small and simple apparatus and is excellent in productivity.
Furthermore, since the recording layer and the shape adjusting layer are sequentially formed by vapor deposition, the film can be formed continuously, so that the productivity is also improved.

Therefore, by sequentially forming the recording layer and the shape adjusting layer by the vapor deposition method, when forming the shape adjusting layer, the recording layer is not deteriorated and the material constituting the shape adjusting layer is excellent. Since the molecular planarity is not impaired, it is more effective in reducing jitter, and an optical recording medium with stable characteristics can be obtained.

An optical recording medium according to an embodiment of the present invention will be described with reference to FIG. (Embodiment 1) FIG. 1 is an enlarged sectional view of an optical recording medium according to an embodiment of the present invention. As shown in FIG. 1, a substrate 1, a recording layer 2, a shape adjusting layer 3, a reflective layer 4, and a protective layer 5 are provided. For the purpose of improving the characteristics, a base layer or the like is provided between the substrate 1 and the recording layer 2. You may.

First, it is desirable that the substrate 1 used in the present invention has a transmittance of 85% or more of a laser beam to be recorded and a small optical anisotropy. The material is, for example, a thermoplastic resin such as a glass acrylic resin, a polycarbonate resin, a polyolefin resin, a polyester resin polystyrene resin, a polymethyl methacrylate resin, an epoxy resin, a thermosetting resin such as an allyl resin, and an ultraviolet curable resin. No. Of these, the most common thermoplastic resin is a polycarbonate resin which can be molded by an injection (compression) molding machine and has high mass productivity and particularly excellent impact resistance.

The substrate thus formed is not particularly limited in thickness, and may be a plate or a film. The shape may be circular or card-like, and the size is not particularly limited. Further, another layer, for example, a solvent-resistant layer such as SiO ₂ or an enhancement layer may be provided on the substrate.

Further, on the surface of the substrate on the recording layer side, means for guiding the traveling path of the laser beam are provided. this is,
For example, address pits formed of pits formed at predetermined intervals may be used, but spiral or concentric guide grooves are desirable. A laser beam travels along the groove to enable recording and reproduction.

Next, the recording layer 2 formed on the guide groove side of the substrate uses an organic dye as its main material. This organic dye is not particularly limited as long as it has some light absorption at the wavelength of the laser light used,
Macrocyclic azaannulene dyes (phthalocyanine dyes, naphthalocyanine dyes, porphyrin dyes, etc.), polymethine dyes (cyanine dyes, merocyanine dyes,
Styryl-based dyes, squarylium-based dyes, etc.), azo-based dyes, quinone-based dyes, and azurenium-based dyes are common. Of these, phthalocyanine dyes are desirable.

The dye is not limited to a single dye, and a plurality of dyes may be mixed. In order to improve recording characteristics, other organic dyes such as a dithiol metal complex and an anthraquinone dye, nitrocellulose, and ethylcellulose , Acrylic resin, polystyrene resin, urethane resin and other resins,
Additives such as a dispersant, a leveling agent and an antifoaming agent can be used in combination as long as the effects of the present invention are not impaired. this,
It is formed by a dry method such as vapor deposition or a wet method such as spin coating.

The shape adjusting layer 3 has a moderately porous structure for adjusting the adhesion to the recording film containing the organic dye and the change in shape of the recording portion, and has a heterocyclic or condensed ring in the molecular structure. There is no particular limitation as long as it is an organic compound having a chemical structure adjacent to a plurality and having a large molecular plane composition, and among them, porphyrazine dyes, perinone dyes, and perylene dyes are preferable.

These organic compounds are not limited to a single compound, but a plurality of such compounds may be mixed, and additives may be used together to such an extent that the effects of the present invention are not impaired. Depending on the organic compound, the production method may be appropriately selected from a dry method and a wet method.However, in order to form a compound by utilizing the planarity of the molecules of the compound, it is necessary to select a compound that can be prepared by the dry method. Desirable, and particularly excellent in productivity if produced by a vapor deposition method.

The reflective layer 4 is made of gold, silver, copper,
Metals such as platinum and aluminum and alloys containing these as main components, metal oxides such as MgO, ZnO and SnO, Si
Nitrides such as N ₄ , AlN, and TiO are exemplified. Above all, gold having high absolute reflectance and excellent storage stability is optimal, but any gold may be used as long as the reflectance required for recording and reproducing with the laser beam used can be secured. This reflective layer is formed by a vacuum evaporation method, a sputtering method, or the like.

The protective layer 5 is formed of a resin having excellent impact resistance and low curing shrinkage as in the case of the above substrate.
This is formed, for example, by applying an ultraviolet curable resin by a spin coating method and then irradiating the applied ultraviolet light to cure the resin. In addition, an epoxy resin, an acrylic resin, a silicone-based hard coat resin, or the like may be used.

[0037]

Embodiments of the present invention will be described below.

Example 1 In Example 1, an outer diameter of 120 mm and an inner diameter of 15 m were formed by injection molding with a polycarbonate resin.
m, a width of 0.6 mm on the recording layer side of a transparent substrate having a thickness of 1.2 mm.
A spiral guide groove of μm, 70 nm in depth and 1.6 μm in pitch is provided. On this substrate, tin (II) phthalocyanine chloride (manufactured by Aldrich Co.) was deposited to a thickness of 5
A recording layer of 0 nm was provided. A shape adjusting layer was formed by vapor deposition of perylene tetracarboxylic acid diimide (manufactured by Tokyo Chemical Industry Co., Ltd.) with a thickness of 50 nm using a perylene dye.

Further, the thickness of the gold sputtered film is 10
A thickness of 7 consisting of a reflective film of 0 nm and an ultraviolet curable resin (DAICHIA CLEAR SD-17 manufactured by Dainippon Ink and Chemicals, Inc.)
An optical recording medium was manufactured by providing a protective layer having a thickness of μm.

(Example 2) In Example 2, as a shape adjusting layer, a copper phthalocyanine (manufactured by Tokyo Chemical Industry Co., Ltd.) was formed by vapor deposition with a porphyrazine dye to a thickness of 40 nm. Thus, an optical recording medium was manufactured.

Example 3 In Example 3, a polyphyrazine-based dye, tetrakis-methoxyphenyl-porphyrin cobalt (Aldrich Co., Ltd.) was used as the shape adjusting layer.
Was formed by vapor deposition to a thickness of 60 nm, and an optical recording medium was produced in the same manner as in Example 1.

Example 4 In Example 4, as a shape adjusting layer, rhodamine 101 was formed using a triphenylmethane dye.
(Aldrich Co., Ltd.) was deposited to a thickness of 50 nm to form an optical recording medium in the same manner as in Example 1.

Example 5 In Example 5, silicon phthalocyanine dichloride was used as a recording layer to a thickness of 70 n.
m, and a shape adjusting layer was provided thereon with a thickness of 40 nm in the same manner as in Example 3, and an optical recording medium was manufactured in the same manner as in Example 1.

For comparison with Examples 1 to 5, optical recording media of Comparative Examples 1 and 2 were produced.

In Comparative Example 1, an optical recording medium was produced in the same manner as in Example 1 except that the shape adjusting layer was omitted, and the structure is shown in FIG.

In Comparative Example 2, copper phthalocyanine, which is a phthalocyanine dye to which a divalent metal is coordinated, was formed to a thickness of 200 nm by vapor deposition to form a recording layer in the same manner as in Example 1. An optical recording medium was manufactured.

The optical recording medium manufactured as described above was applied to a 790 nm wavelength using a Pulstec CD-R tester.
Recording and reproduction were performed at m and a linear velocity of 1.4 m / sec, and jitter was measured. Here, the jitter of the 11T signal and 60 ° C., 9
The characteristics after storage under 0% RH environment are shown in Table 1 as ○ when there is almost no deterioration and X when there is much deterioration.

[0048]

[Table 1]

As is clear from Table 1 in comparison between Comparative Example 1 having no shape adjusting layer and Examples 1 to 5, the provision of the shape adjusting layer reduced the 11T jitter to about half or less. Can be reduced to In particular, when a perylene dye and a porphyrazine dye were used as the shape adjusting layer (Example 1)
In 3), the effect is excellent, the storage stability is good, and stable characteristics are obtained.

Further, for the recording layer below the shape adjusting layer, when the material constituting the recording layer is a phthalocyanine dye, a dye having a coordinated divalent metal and a dye having a coordinated tetravalent metal derivative are used. In comparison (Examples 1 to 5 and Comparative Example 2), a dye of a tetravalent metal such as Si or Sn can reduce the thickness of the recording layer, so that the effect of reducing jitter is large.

On the other hand, the recording layers of the above Examples and Comparative Examples were
According to EM observation, in Comparative Example 1 having no shape adjustment layer,
The periphery of the pit was significantly deformed, and the pit boundary was not clear. On the other hand, in each of the cases where the shape adjusting layer was provided, the boundary portion between the pits was clear, and in particular, clear pit shapes were recognized with the perylene dye and the porphyrazine dye.

[0052]

As described above, the optical recording medium of the present invention is provided with a shape adjusting layer made of an organic compound on the recording layer.
Since the shape of the substrate or the recording layer changes to some extent due to the temperature rise, and the shape adjusting layer can absorb some of the change without peeling off from the recording layer, the shape of the pit peripheral portion can be adjusted, Clear pits can be formed. As a result, jitter can be reduced, and stable characteristics can be obtained.

[Brief description of the drawings]

FIG. 1 is a sectional view showing the configuration of an optical recording medium according to an embodiment of the present invention;

FIG. 2 is a configuration sectional view of an optical recording medium in a comparative example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Substrate 2 Recording layer 3 Shape adjustment layer 4 Reflection layer 5 Protective layer

 ──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Tomiji Hosaka 1006 Kazuma Kadoma, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd.

Claims (4)

[Claims] An optical recording medium in which a recording layer containing an organic dye that transmits and absorbs a laser beam, a reflective layer, and a protective layer are sequentially formed on a substrate. An optical recording medium provided with a shape adjusting layer containing at least one organic compound having a heterocyclic ring or a condensed ring. 2. The optical recording medium according to claim 1, wherein the shape adjusting layer contains either a porphyrazine dye or a perylene dye and has crystallinity. 3. An organic dye constituting a recording layer, wherein: The optical recording medium according to claim 1, wherein
(In the chemical formula 1, M is a tetravalent metal derivative, and the metal is Si or Sn. Here, the substituents Y1 and Y2 to be introduced into the tetravalent metal are not particularly limited. , An oxygen atom, a substituted or unsubstituted alkyl group,
It may have a substituted or unsubstituted alkoxy group, a substituted or unsubstituted acyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted aryloxy group, and the like. The substituents X ₁ to X ₁₆ are not particularly limited as long as they can be introduced into a phthalocyanine ring, and include, for example, a hydrogen atom, a halogen atom, a nitro group, an amino group, a substituted or unsubstituted alkyl group, It may have an unsubstituted alkoxy group, a substituted or unsubstituted alkylthio group, a substituted or unsubstituted aryl group, a substituted or unsubstituted aryloxy group, and the like. ) 4. The optical recording medium according to claim 1, wherein the recording layer and the shape adjusting layer are sequentially formed by a vapor deposition method.