JP3470157B2 - Optical recording medium and manufacturing method thereof - 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 having improved optical characteristics and a manufacturing method thereof.

[0002]

2. Description of the Related Art In recent years, the development of a write-once CD (compact disc) has become active. This is a conventional CD
Unlike a CD, a user can record information and the signal after recording satisfies the standard of the conventional CD, so that a commercial CD
It has the feature that it can be played back by the player. As one of methods for realizing such a medium, Japanese Patent Laid-Open No. 2-4
In Japanese Patent No. 2652, it is proposed that a dye is spin-coated on a substrate to provide a recording layer, and a metal reflective layer is provided behind it. Furthermore, Japanese Patent Laid-Open No. 2-132
As described in Japanese Patent No. 656, by appropriately selecting the complex refractive index and the film thickness of the recording layer, the signal after recording becomes C
The D standard is satisfied, and a write-once CD can be realized.

[0003]

However, Japanese Unexamined Patent Application Publication No.
The write-once type CDs using the dyes disclosed in JP-A-42652 and JP-A-2-132656 are still insufficient in light resistance. In other words, the signal characteristics change when exposed to sunlight for a long time, and the CD
There is a drawback that the standard cannot be satisfied. This is because the dye material used in the recording layer, especially the cyanine dye that has been conventionally used, is changed by light. Therefore, in order to suppress this change, Japanese Patent Laid-Open No. 63-
As disclosed in Japanese Patent No. 159090, it is known that a recording layer contains a light stabilizer. However, when the light stabilizer is added in a small amount (20% or less), sufficient light resistance cannot be obtained, and conversely, when added in a large amount (20% or more), the optical and / or optical properties of the recording layer are not increased. There is a problem that the thermal characteristics change and various signal qualities deteriorate.

On the other hand, as another means for improving the light resistance,
It has also been proposed to use a phthalocyanine compound, which is a highly light-resistant dye, as a recording layer material (Japanese Patent Laid-Open No. 58-183).
296 and 58-37851). However, the phthalocyanine-based compound is generally insufficient in solubility for forming a film by spin coating. Further, it has been difficult to satisfy the optical properties required for the recording layer, especially the high refractive index. The optical characteristics of the recording layer depend on the extinction coefficient (which means the absorbance per unit film thickness) of the film in the vicinity of the laser light wavelength for recording and reproduction, and satisfy the optical characteristics required for the write-once CD. In order to achieve this, a certain degree of extinction coefficient is required, but in general, the film of a phthalocyanine compound has a smaller extinction coefficient than conventional cyanine dyes (about 1/3 to 1/2 that of cyanine dyes). by.

Therefore, it is an object of the present invention to provide an optical recording medium having a recording layer having high light resistance and required optical characteristics, more specifically, a specific phthalocyanine having improved optical characteristics and solubility. An object of the present invention is to provide an optical recording medium having a film of a compound as a recording layer, and a method for producing the same.

[0006]

As a result of earnest studies, the inventors of the present invention have found that in the above-mentioned conventional optical recording medium, the phthalocyanine-based compound has a small absorption coefficient for the film of the phthalocyanine-based compound as the recording layer. The molecule has a planar structure and is likely to undergo molecular association. When molecules of the phthalocyanine-based compound associate with each other, the optical absorption spectrum becomes broad due to the intermolecular interaction, and the solubility in a solvent decreases due to this molecular association. Is a laser light wavelength region (760 to 800
In order to obtain an appropriate complex refractive index in (nm), it was found that the absorption peak wavelength (λmax) of the recording layer is more preferably in the range of 720 to 740 nm, and the present invention has been completed.

That is, according to the present invention, in an optical recording medium in which at least a recording layer is provided on a substrate, the recording layer comprises a metal phthalocyanine compound (1) represented by the following general formula (I) and imidazole, Benzimidazole and
Provided is an optical recording medium containing, as a main component, at least one nitrogen-containing compound (2) selected from a thiazole derivative .

[Chemical 1] (In the formula, M and A ^{1 to} A ⁸ respectively represent the following: M: Mn ²⁺ , Fe ²⁺ , Co ²⁺ , Zn ²⁺ and Cd ^2+.
At least one divalent metal atom selected from A ¹ and A ² , A ³ and A ⁴ , A ⁵ and A ^6, and A ⁷ and A ⁸ : either one of the following general formula (II) A thiophenyl group represented, the other is a hydrogen atom,

[Chemical 2] R ¹ : an alkyl group having 1 to 4 carbon atoms or an alkoxy group having 1 to 4 carbon atoms, R ^{2 to} R ⁵ : an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a halogen atom or a hydrogen atom . )

Further, according to the present invention, in a preferred embodiment,
Te, before type recording layer is an optical recording medium are those having a light absorption peak wavelength (.lambda.max) are provided in a range of 720～740Nm.

Furthermore, according to the present invention, a metal phthalocyanine compound represented by the above general formula (I) is directly or via another layer on a substrate having information pits and / or guide grooves formed on the surface thereof. (1) and imidazole and benzii
When less selected from imidazole and thiazole derivatives
Also , a recording layer containing one kind of nitrogen-containing compound (2) as a main component is provided by coating film forming means, and a light reflecting layer is provided thereon by vacuum film forming means directly or through another layer. There is provided a method for manufacturing an optical recording medium, which comprises providing a protective layer thereon.

The optical recording medium of the present invention has the above general formula (I).
Since the metal phthalocyanine compound (1) represented by the formula (1) is provided with a recording layer composed of a film in which the above-mentioned nitrogen-containing compound (2) having a function of preventing association of the phthalocyanine compound is coordinate-bonded. , The molecular association of the phthalocyanine-based compound when it is thinned is suppressed, the broad absorption spectrum is avoided, and the solubility capable of forming a film by spin coating is maintained. Therefore, an appropriate complex refractive index can be obtained.

The present invention will be described in detail below. In the optical recording medium of the present invention, the recording layer comprises the metal phthalocyanine compound (1) represented by the general formula (I), imidazole,
Selected from benzimidazole and thiazole derivatives
At least one nitrogen-containing compound (2) is a main component. That is, in the optical recording medium of the present invention, the general formula as a recording layer and a metal phthalocyanine compound represented by (I) (1), Imida
A mixture with at least one nitrogen-containing compound (2) selected from sol, benzimidazole and thiazole derivatives is used. In the metal phthalocyanine compound (1), the central metal M has -N = in the nitrogen-containing compound.
Alternatively, the -N <group is easily coordinated, and the nitrogen-containing compound is introduced between the molecules of the metal phthalocyanine compound, whereby the molecular association of the metal phthalocyanine compound can be prevented. Further, as described above, in the metal phthalocyanine-based compound, the absorption peak wavelength (λmax) of the recording layer is in the range of 720 to 740 nm, which is extremely high for obtaining an appropriate complex refractive index in the vicinity of the laser light wavelength. It has been found by the present inventor that the preferable one is α-position (A ¹ , A ² , A ³ , A ⁴ , A in the phthalocyanine ring.
⁵ , due to the effect of the phenylthio group of A ⁶ , A ⁷ , A ⁸ ),
The λmax of the recording layer film falls within a range of approximately 720 to 740 nm, and further, it has the solubility capable of forming a film by spin coating.

Imidazole and benz used in the present invention
Less selected from imidazole and thiazole derivatives
Specific examples of the one type of nitrogen-containing compound (2) include, but are not limited to, the following compounds. These are highly effective in preventing the association of the metal phthalocyanine compound, and durability (heat resistance, light resistance) that is excellent in. Further, from the viewpoint of maintaining the thermal stability of the recording layer, the nitrogen-containing compound preferably has a melting point of 150 ° C. or higher. If the melting point is less than 0.99 ° C., the characteristic (particularly optical characteristics) of the film under a high-temperature environment is not easy to change.

[0013] Lee imidazole, benzimidazole, 5,
6-dimethylbenzimidazole, 2,5,6-trimethylbenzimidazole, 2-methylnaphthoimidazole
Le, base Nzuchiazo Le, Application Benefits phenyl imidazole, Po <br/> Li benzimidazole, polyimidazole, polythiazole like.

The metal phthalocyanine compound (1) used in the present invention has a structure represented by the general formula (I), and the central metal M is Mn, Fe, Co,
Zn and Cd can be used. In the phthalocyanine compound (1) having these central metals, the -N = or -N <group in the nitrogen-containing compound (2) is easily coordinated with the central metal, and the effect of preventing association is high. On the other hand, R ^{1 to} R ^{5 in the} phenylthio group represented by the following general formula (II) may be the same or different, and R ¹ is an alkyl group having 1 to 4 carbon atoms or 1 to 4 carbon atoms. 4 is an alkoxy group, and R ^{2 to} R ⁵ are alkyl groups having 1 to 4 carbon atoms,
It represents an alkoxy group having 1 to 4 carbon atoms, a halogen atom or a hydrogen atom.

[Chemical 2] R ^{1 to} R ⁵ can improve solubility, extinction coefficient of film, heat resistance and the like. R ¹ and R ⁵ are particularly effective.

The mixing ratio of the nitrogen-containing compound (2) having a group (-N = or -N <group) capable of coordinating to the metal phthalocyanine compound and the metal phthalocyanine compound (1) is The molar ratio of 1/2 to 2/1 [nitrogen-containing compound (2) / metal phthalocyanine compound (1) ratio] is preferable. If the molar ratio is less than 1/2, the effect of the nitrogen-containing compound cannot be sufficiently obtained, and conversely if the molar ratio exceeds 2/1, the dye concentration in the film becomes low, and in any case, the extinction coefficient of the film becomes small.

Further, as a recording layer material, in addition to the phthalocyanine compound (1) and the nitrogen-containing compound (2), any dye conventionally known as a recording material of an information recording medium is mixed. Can be used. Examples of such dyes include cyanine dyes, pyrylium / thiopyrylium dyes, azurenium dyes, squarylium dyes, metal complex salt dyes such as Ni and Cr, naphthoquinone / anthraquinone dyes, indophenol dyes, India Examples thereof include aniline type dyes, triphenylmethane type dyes, triallylmethane type dyes, aminium type / diimmonium type dyes, and nitroso compounds. Further, if necessary, other third component such as binder, stabilizer and the like can be contained. Incidentally, the film thickness of the recording layer is preferably 100 to 5000 Å,
Particularly, 500 to 3000Å is desirable. The thickness of the recording layer is
This is because if it is thinner than this range, the recording sensitivity is lowered, and if it is thicker, the reflectance is lowered.

The substrate used in the present invention can be arbitrarily selected from various materials used as substrates for conventional information recording media. Examples of substrate materials include
Examples thereof include acrylic resins such as polymethylmethacrylate, vinyl chloride resins such as polyvinyl chloride and vinyl chloride copolymer, epoxy resins, polycarbonate resins, amorphous polyolefins, polyesters, glasses such as soda lime glass, and ceramics. In particular, from the viewpoint of dimensional stability, transparency and flatness, polymethyl methacrylate, polycarbonate resin, epoxy resin, amorphous polyolefin, polyester, glass and the like can be mentioned.

An undercoat layer may be provided on the surface of the substrate on which the recording layer is provided for the purpose of improving flatness, improving adhesive strength and preventing alteration of the recording layer. Examples of the material of the undercoat layer include polymethylmethacrylate and acrylic acid /
Methacrylic acid copolymer, styrene / maleic anhydride copolymer, polyvinyl alcohol, N-methylol acrylamide, styrene / sulfonic acid copolymer, styrene / vinyltoluene copolymer, chlorosulfonated polyethylene, nitrocellulose, polyvinyl chloride Polymer substances such as chlorinated polyolefins, polyesters, polyimides, vinyl acetate / vinyl chloride copolymers, ethylene / vinyl acetate copolymers, polyethylene, polypropylene, polycarbonates: Organic substances such as silane coupling agents: Inorganic oxides Inorganic substances such as (SiO ₂ , Al ₂ O ₃ etc.) and inorganic fluorides (MgF ₂ ) can be mentioned. The layer thickness of the undercoat layer is generally in the range of 0.005 to 20 μm, preferably 0.01 to 10 μm.

Further, a pregroup layer may be provided on the substrate (or undercoat layer) for the purpose of forming a groove for tracking or an unevenness representing information such as an address signal. As the material for the pregroup layer, a mixture of at least one monomer (or oligomer) of acrylic acid monoester, diester, triester, and tetraester and a photopolymerization initiator can be used.

Further, a reflective layer may be provided on the recording layer for the purpose of improving the S / N ratio, the reflectance and the sensitivity during recording. The light-reflecting substance that is the material of the reflecting layer is a substance having a high reflectance for laser light, and examples thereof include Mg, Se, Y, Ti, Zr, Hf, V and N.
b, Ta, Cr, Mo, W, Mn, Re, Fe, Co,
Ni, Ru, Rh, Pd, Ir, Pt, Cu, Ag, A
u, Zn, Cd, Al, Ca, In, Si, Ge, T
Metals and semimetals such as e, Pb, Po, Sn and Si can be mentioned. Of these, preferred is A
u, Al and Ag. These substances may be used alone or in combination of two or more or as an alloy. The layer thickness of the reflective layer is generally 100 to 30.
It is in the range of 00Å. The reflective layer may be provided between the substrate and the recording layer. In this case, information recording / reproduction is performed from the recording layer side (the side opposite to the substrate).

Further, a protective layer may be provided on the recording layer (or the reflective layer) for the purpose of physically and chemically protecting the recording layer and the like. This protective layer may be provided on the side of the substrate on which the recording layer is not provided for the purpose of enhancing scratch resistance and moisture resistance. Examples of materials used for the protective layer include
Examples thereof include inorganic substances such as SiO, SiO ₂ , MgF ₂ , and SnO ₂ , thermoplastic resins, thermosetting resins, and UV curable resins. The thickness of the protective layer is generally 500Å
˜50 μm.

Next, a method of manufacturing the optical recording medium of the present invention will be described. The method for producing an optical recording medium of the present invention comprises a metal phthalocyanine compound represented by the general formula (I) directly or through another layer on a substrate having information pits and / or guide grooves formed on the surface. A recording layer containing (1) and the nitrogen-containing compound (2) as main components is provided by coating film forming means, and a light reflection layer is provided thereon by vacuum film forming means directly or through another layer. It is characterized in that a protective layer is provided thereon. That is, the manufacturing method of the present invention comprises the following steps. (A) A metal phthalocyanine compound (1) represented by the general formula (I) directly or through another layer on a substrate having information pits and / or guide grooves formed on its surface.
And a step of providing a recording layer containing the above-mentioned nitrogen-containing compound (2) as a main component by coating film forming means, (b) providing a light reflecting layer on the recording layer directly or via another layer by vacuum film forming means. And (c) providing a protective layer on the recording layer.

(Recording Layer Forming Step) In the method of the present invention, first, information pits and / or
Alternatively, a recording layer containing the metal phthalocyanine compound (1) and the nitrogen-containing compound (2) as main components is formed on the substrate having the guide groove formed directly or through another layer by coating and forming means. Provided by. That is, the recording layer in the present invention is composed of a film in which the phthalocyanine compound (1) and the nitrogen-containing compound (2) are coordinate-bonded, and the recording layer dissolves the above two compounds to form a liquid coating solution. It can be easily obtained by coating as a substrate. As a solvent for adjusting this coating solution, a known organic solvent (for example, alcohol, cellosolve, carbon halide, ketone,
Ether, etc.) can be used. As the coating method, the spin coating method is preferable because the layer thickness can be controlled by adjusting the concentration and viscosity of the recording layer and the drying temperature of the solvent.

An undercoat layer is provided on the surface of the substrate on which the recording layer is provided for the purpose of improving the flatness of the surface of the substrate, improving the adhesive strength, and preventing alteration of the recording layer. The undercoat layer in this case is prepared by, for example, dissolving or dispersing the above-mentioned undercoat layer substance in a suitable solvent to prepare a coating solution, and then applying the coating solution by spin coating, dip coating, extrusion coating or the like. Can be formed by applying to the surface of the substrate.

(Light-Reflecting Layer Forming Step) In the method of the present invention, a light-reflecting layer is then provided on the recording layer directly or via another layer by a vacuum film forming means.
That is, the light reflecting layer is formed on the recording layer by, for example, vapor deposition, sputtering or ion plating of the above-mentioned light reflecting substance.

(Protective Layer Forming Step) In the method of the present invention, a protective layer is provided on the light reflecting layer. That is, it is formed by vacuum film formation or application film formation of the protective layer material made of the above-mentioned inorganic substance or various resins. In particular, it is preferable to use a UV curable resin, which is formed by spin coating the resin and then irradiating it with ultraviolet rays to cure it.

[0027]

The present invention will be described below with reference to examples, but the present invention is not limited thereto.

Example 1 A phthalocyanine dye represented by (A) in Table 1 below and 1
-Tetramethylbenzylbenzimidazole was dissolved in chloroform at a molar ratio of about 1: 1.2 to form a coating solution, which was spin-coated on a glass substrate having a diameter of 120 mm and a thickness of 1.2 mm to form a recording layer. The optical absorption spectrum of this recording layer is shown in FIG. As is clear from FIG. 1, the optical absorption spectrum of this recording layer had a sharp shape with a high right peak (long wavelength side) of the absorption band.

Comparative Example 1 A recording layer was provided by dissolving a phthalocyanine dye represented by (A) in Table 1 below in chloroform to prepare a coating solution and spin-coating it on a glass substrate having a diameter of 120 mm and a thickness of 1.2 mm. . The optical absorption spectrum of this recording layer is shown in FIG. As is apparent from FIG. 1, the optical absorption spectrum of this recording layer had a broader absorption band shape than the optical absorption spectrum of Example 1.

Example 2 A recording layer was provided in the same manner as in Example 1 except that the phthalocyanine dye in Example 1 was replaced with the phthalocyanine dye represented by (D) in Table 1 below. The optical absorption spectrum of this recording layer is shown in FIG. As is clear from FIG. 2, the optical absorption spectrum of this recording layer had a sharp shape with a high right peak (long wavelength side) of the absorption band.

Comparative Example 2 A recording layer was provided in the same manner as in Comparative Example 1 except that the phthalocyanine dye in Comparative Example 1 was replaced with the phthalocyanine dye represented by (D) in Table 1 below. The optical absorption spectrum of this recording layer is shown in FIG. As is clear from FIG. 2, the light absorption spectrum of this recording layer is
The shape of the absorption band was broad compared with the light absorption spectrum of.

Example 3 A recording layer was provided in the same manner as in Example 1 except that the phthalocyanine dye in Example 1 was replaced with the phthalocyanine dye represented by (G) in Table 1 below. The optical absorption spectrum of this recording layer is shown in FIG. As is clear from FIG. 3, the light absorption spectrum of this recording layer had a sharp shape with a high right peak (long wavelength side) of the absorption band.

Comparative Example 3 A recording layer was provided in the same manner as in Comparative Example 1 except that the phthalocyanine dye in Comparative Example 1 was replaced with the phthalocyanine dye represented by (G) in Table 1 below. The optical absorption spectrum of this recording layer is shown in FIG. As is clear from FIG. 3, the light absorption spectrum of this recording layer is
The shape of the absorption band was broader than that of the light absorption spectrum of.

Examples 4 to 15 and Comparative Examples 4 to 9 The phthalocyanine dyes represented by (A) to (R) in Tables 1 and 2 below and 5,6-dimethylbenzimidazole in a molar ratio of about 1: 2. Was dissolved in chloroform, the recording layer was formed in the same manner as in Example 1, and λmax was determined. Also,
Alcohol which is a spin coating solvent for a polycarbonate substrate which is generally used as a substrate for an optical disc,
The film forming properties of cellosolve and alkane were investigated. Further, the heat resistance of the film was measured at 120 ° C. for 200 hours, and the residual rate of absorption [Ab
s (λmax) 120 ° C., 200 hours / Abs (λma
x) Initial stage]. As a result, in the samples (A to L) of the present invention, λmax of the recording layer was in the range of 720 to 740 nm, and the solvent containing cellosolve (2-ethoxyethanol or the like) or alkane (methylcyclohexane) as a main component was used. , Can be deposited on a polycarbonate substrate,
Heat resistance was also good, but comparative samples (M to R)
Could not satisfy all of the above λmax, film formability, and heat resistance.

Example 16 A substrate having a guide groove concavo-convex pattern having a depth of about 1200 Å on the surface of a polycarbonate substrate having a diameter of 120 mm and a thickness of 1.2 mm was prepared, and a dye represented by (C) in Table 1 below was prepared. A recording layer was formed on the substrate surface by dissolving 5,6-dimethylbenzimidazole in a mixed solvent of ethyl cellosolve / tetrahydrofuran / methylcyclohexane (= 1/1/6) at a molar ratio of 1: 1 and spin coating. Was set up. The thickness of the recording layer was about 1500Å.
Au was formed on the recording layer by Au sputtering to a thickness of about 800 Å to form a reflective layer, and a protective layer made of an ultraviolet curable resin was further formed on the recording layer to a thickness of about 5 μm to provide the optical recording medium of the present invention. It was made. The obtained optical recording medium has a wavelength of 785n.
m, N.M. A. EFM at 0.5 and linear velocity of 1.4 m / s
When the signal was recorded and the reproduced signal was evaluated, itop was 69% and Cl error was 220 or less, which were values satisfying the CD standard.

[0036]

[Table 1]

[0037]

[Table 2]

[0038]

According to the optical recording medium of claim 1, the recording layer comprises the metal phthalocyanine compound (1) represented by the general formula (I), imidazole, benzimidazole and thiazo.
Since the main component is at least one nitrogen-containing compound (2) selected from the aryl derivatives , the molecular association of the phthalocyanine compound is suppressed and the durability is improved.
It has excellent optical characteristics such as excellent heat resistance and light resistance and an appropriate complex refractive index in the laser light wavelength range (760 to 800 nm).

According to the optical recording medium of the second aspect , since the light absorption peak wavelength of the recording layer is in the range of 720 to 740 nm, an appropriate complex refractive index can be more surely obtained at the laser light wavelength. The effect is added.

In the optical recording medium manufacturing method of the third aspect , the recording layer is formed by the coating film forming means, and the light reflecting layer is formed by the vacuum film forming means. Therefore, the optical recording medium of the present invention. Can be easily and stably manufactured.

[Brief description of drawings]

FIG. 1 is an optical absorption spectrum diagram of a recording layer obtained in Example 1 and Comparative Example 1.

FIG. 2 is a light absorption spectrum diagram of a recording layer obtained in Example 2 and Comparative Example 2.

FIG. 3 is an optical absorption spectrum diagram of a recording layer obtained in Example 3 and Comparative Example 3.

Continuation of front page (56) Reference JP-A-6-124479 (JP, A) JP-A-61-154888 (JP, A) JP-A-5-262042 (JP, A) JP-A-2-179790 (JP , A) (58) Fields surveyed (Int.Cl. ⁷ , DB name) G11B 7/24 G11B 7/26

Claims (3)

(57) [Claims] 1. A optical recording medium formed by providing at least a recording layer on a substrate, the recording layer is a metal phthalocyanine compound represented by the following general formula (I) and (1), Imida
At least one nitrogen-containing compound (2) selected from sol, benzimidazole and thiazole derivatives ,
An optical recording medium having a main component. [Chemical 1] (In the formula, M and A ^{1 to} A ⁸ each represent the following: M: at least one divalent selected from Mn ²⁺ , Fe ²⁺ , Co ²⁺ , Zn ²⁺ and Cd ^2+. Metal atoms of A ¹ , A ² , A ³ and A ⁴ , A ⁵ and A ⁶ and A ⁷ and A ⁸ : either one of them is a thiophenyl group represented by the following general formula (II), and the other is hydrogen. Atom, R ¹ : an alkyl group having 1 to 4 carbon atoms or an alkoxy group having 1 to 4 carbon atoms, R ^{2 to} R ⁵ : an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a halogen atom or a hydrogen atom . ) 2. The optical recording medium according to claim 1, wherein the recording layer has a light absorption peak wavelength (λmax) in a range of 720 to 740 nm. 3. A metal phthalocyanine compound (1) represented by the general formula (I) and imidazole on a substrate having information pits and / or guide grooves formed on the surface thereof, directly or through another layer. , Benzimidazole and thia
A recording layer containing at least one nitrogen-containing compound (2) selected from sol derivatives as a main component is provided by coating and film forming means, and a light reflecting layer is vacuum-formed directly thereon or through another layer. provided by the membrane unit further process for producing an optical recording medium according to claim 1 or 2, characterized in that a protective layer thereon.