KR19980047026A - Oxidation resistant optical record carrier - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an oxidation resistant optical recording medium, and more particularly, to a recording layer in an optical recording medium in a heat mode in which a recording layer, a reflective layer, and a protective layer are laminated on a substrate. The present invention relates to a new oxidation resistant optical recording medium having improved reliability by improving the durability and moisture resistance of a recording layer by newly adding and mixing an oxidation resistance improving agent to organic dyes.

Description

Oxidation resistant optical record carrier

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an oxidation resistant optical recording medium, and more particularly, to a recording layer in an optical recording medium in a heat mode in which a recording layer, a reflective layer, and a protective layer are laminated on a substrate. The present invention relates to a new oxidation resistant optical recording medium having improved reliability by improving the durability and moisture resistance of a recording layer by newly adding and mixing an oxidation resistance improving agent to organic dyes.

In general, an optical disc used as a means for recording and reproducing various information such as an image or a voice such as a character or a figure, may be read only, write once, or callable depending on a function. -Writable). Play-only type includes video disc (VD), digital audio disc (CD) and CD-ROM for data, and recordable optical disc is used as external recording device for large computer to record document file system and code information. Also called direct read after write media and write once read many media (WORM). A WORM Type compact disc that can be written once as a recordable optical disc is an optical recording medium by a heat mode.

The optical recording medium by such a heating method generally has a structure in which a recording layer, a reflective layer, and a protective layer are sequentially stacked on a substrate on which a groove portion is formed, wherein the recording layer is formed in a state where the groove portion and the land portion are formed. . Conventionally, in such an optical recording medium, a low melting point metal such as Te is vacuum-deposited on an insulating substrate to form a recording layer, and when the input data is irradiated to the recording layer with laser light or the like, the corresponding information is corresponding to the input information. Through the surface irregularities of the recording layer, the reflectance of the recording medium changes. Therefore, when the recording is reproduced, when the weak laser light is irradiated, the difference in reflectance is detected according to the change state of the recording layer and thereby the input information is reproduced [M. Okuda et al, J. Japan Appl. Phys., 26, 718 (1987), C. J. Van der Poel et al, J. Appl. Phys., 59, 1819 (1986)].

However, the conventional optical recording medium using the Te recording layer has room for improvement, such as the formation of the recording layer by the vacuum deposition method, which leads to a decrease in productivity, and the lack of high density recording due to its high conductivity even during local heating.

As part of this improvement, in recent years, organic pigments such as Phthalocyanine and Cyanine, which have lower reflectance but excellent reflectivity among nonmetallic components, are used instead of metal deposition films such as Te as a material used for forming a recording layer. An optical recording medium for use as a layer material has been developed and attracts attention (Japanese Patent Laid-Open Nos. 5-131750, 5-139044, 5-147356, 5-325252 (1993)).

Since the optical recording medium using the organic dye is formed by the spin coating method when the recording layer is formed, it is easier to form the recording layer than the conventional case formed by the vacuum deposition film, thereby increasing the productivity of the product. It is known that it is suitable for high density recording because the thermal conductivity of the recording layer material is low and local heating is possible.

In particular, the cyanine dye is known to be more useful because its cyanine dye exhibits high absorption and reflection at the laser wavelength of 700 to 900 nm, which is an IR semiconductor.

However, in the case of the conventional optical recording medium using the cyanine-based pigment in the recording layer, the durability is relatively weak compared to the use of other materials, so that the recording sensitivity is greatly decreased as the number of times of reproduction increases.

Therefore, in the present invention, in order to solve the problems in the conventional optical recording medium containing the organic pigment, by using a new addition of the oxidation resistance improver to the organic pigment to improve the durability and moisture resistance to improve the recording characteristics and reliability of the product The purpose is to make it happen.

1 is a cross-sectional structural view showing an embodiment of an optical recording medium according to the present invention.

Explanation of symbols for main parts of the drawings

1-substrate 2-recording layer

3-reflective layer 4-protective layer

5-groove 6-land

The present invention provides an optical recording medium in which an organic dye recording layer, a reflective layer, and a protective layer are sequentially stacked on a substrate, wherein the recording layer contains 0.1 to 20% by weight of the cobalt compound-based oxidation resistance enhancer in the overall composition of the organic dye recording layer. It is characterized by that it contains.

Referring to the present invention in more detail as follows.

The present invention is characterized in that the conventional organic dye-containing optical recording medium contains an oxidation resistance enhancer in addition to the organic dye. Such an oxidation resistance improver is particularly cobalt-based compound having a property of reversibly bonding with oxygen. Oxidation resistance enhancers may be used, for example, a component represented by the following Chemical Formula 1 may be used.

In the above formula,

A is Li ⁺ , Na ⁺ or Cs ⁺

m, n, l are each independently 0 or an integer of 1 to 10,

DMF means N, N-dimethylformamide.

The oxidation resistance improving agent according to the present invention is used together with an organic dye mainly composed of the following compound of formula (2), which has been conventionally used, and when they are mixed together to form a coating liquid for forming a recording layer, The coating layer is formed by dissolving in a mixed solution or a single solution of the two solutions represented by 4 and forming the coating solution by spin coating on the substrate.

In the above formula,

R ₁ , R ₂ , and R ₃ are each independently an alkyl group having ₁ to ₆ carbon atoms,

n is an integer of 1 to 10,

X is a halogen atom, perhalogenic acid, phosphorus 4-fluoro or toluene sulfonic acid,

A is a ring substituent containing a benzene or naphthalene ring.

Among the above formulas,

R ₄ is CF ₃ , H or CF ₂ (H)-(CF ₂ ) _n −, where n is 1, 2, 3, 4 or 5,

R ₅ , R ₆ , R ₇ and R ₈ are each independently -OH, -H, -CH ₃ , ,

Or C _n H _{2n + 1} -COO-, wherein m and n are each independently an integer of 1 to 4;

That is, the coating liquid prepared as described above is spin-coated on the substrate 1 on which the groove portion 5 and the land portion 6 are formed in the structure as shown in FIG. 1 to form the recording layer 2. Subsequently, the reflective layer 3 and the protective layer 4 are formed in a conventional manner to manufacture an optical recording medium.

In this case, a conventional polycarbonate (PC) substrate may be used as the substrate, and the reflective layer may be Au having a higher reflectance than the prior art. In addition, as the protective layer, UV curable resin may be used for the purpose of protecting the substrate.

On the other hand, the oxidation resistance improver newly used in the present invention serves as an antioxidant by binding to oxygen while being present with conventional organic pigments in the recording layer as in the reaction scheme.

In more detail, the cyanine organic pigment system has a disadvantage in that it is decomposed by light and singlet oxygen, and this oxidation resistance enhancer reversibly combines with oxygen to block the contact between the organic pigment and oxygen and thus uses only conventional organic pigments. Compared to the case it will significantly reduce the decomposition of organic pigments. Therefore, to compensate for the weakness of the oxidation resistance of the cyanine organic pigment is significantly improved durability and moisture resistance.

According to the present invention, such an oxidation resistance improving agent may be used in an amount of 50 wt% or less with respect to the pigment in the composition constituting the entire recording layer, but it is preferable to use 0.1 to 20 wt% with respect to the dye, and if the amount thereof is too small If the addition effect cannot be expected and is excessively large, there is a problem that the recording characteristics are deteriorated due to the decrease of the relative amount of pigment.

On the other hand, a single recording layer containing the oxidation resistance improver according to the present invention is spin-coated on a substrate with a thickness of usually 30 to 500 nm, preferably 50 to 250 nm. If it is thick, there is a fear of reflectance decrease.

Hereinafter, the present invention will be described in detail with reference to Examples, but the present invention is not limited by Examples.

Example 1

On the surface of the polycarbonate board | substrate of diameter 120mm, the disk substrate in which the groove part (Wobble Groove) was formed in the range of 46-116mm in diameter was prepared. On the other hand, 1.5% by weight of the cyanine dye as shown in the following formula (5) and the oxidation resistance enhancer of the following formula (6) to the solvent to which 5% by weight of ethylene glycol monomethyl ether acetone was added to 2,2,3,3-tetrafluoropropanol 0.23 compared to the pigment Dissolved by weight% to form a coating liquid.

The coating liquid is coated with an optical recording layer by spin coating on a portion having a diameter of 38 mm or more of the substrate. The film thickness of the optical recording layer is set to be about 1300-1500 kPa in the land portion and the groove portion. When a reflective layer having a thickness of about 800 으로 with gold is deposited on the optical recording layer thus manufactured by using a sputtering machine, and then a protective layer having a thickness of about 3 μm is formed thereon using an ultraviolet curable resin. Optical recording media can be created. Using a semiconductor laser light having a wavelength of 780 nm in the optical recording medium thus produced, CD format signals were recorded under a recording power of 6.5 mW and linear velocity of 1.3 m / sec., And the reproduction signal of the recorded signal was measured. Next, the recording signal of the optical recording medium was measured using a semiconductor laser light having a wavelength of 780 nm, and the reproduction signal that was reproduced one million times under the conditions of 0.7 mW of reproduction power and 1.3 m / sec. Investigate. In addition, the optical recording medium was left at 80 ° C. and 80% RH (Relative Humidity) for 800 hours, and then the playback signal was measured after standing. This measurement evaluated the moisture resistance reliability.

Example 2

On the surface of the polycarbonate board | substrate of diameter 120mm, the disk substrate in which the groove part (Wobble Groove) was formed in the range of 46-116mm in diameter was prepared. Meanwhile, 2.0% by weight of the cyanine dye as shown in Formula 7 and the oxidation-resistant resin of Formula 6 above 0.25 in the solvent to which 5% by weight of ethylene glycol monomethyl ether acetone was added to 2,2,3,3-tetrafluoropropanol. Dissolved by weight% to form a coating liquid. It evaluated by the method similar to Example 1 using the said coating liquid.

Example 3

On the surface of the polycarbonate board | substrate of diameter 120mm, the disk substrate in which the groove part (Wobble Groove) was formed in the range of 46-116mm in diameter was prepared. On the other hand, 2.5% by weight of the cyanine pigment represented by the following formula (8) and the oxidation resistance improver of the above formula (6) to the solvent to which 5% by weight of ethylene glycol monomethyl ether acetone was added to 2,2,3,3-tetrafluoropropanol 3.0 compared to the pigment Dissolved by weight% to form a coating liquid. It evaluated by the method similar to Example 1 using the said coating liquid.

Comparative example

On the surface of the polycarbonate board | substrate of diameter 120mm, the disk substrate in which the groove part (Wobble Groove) was formed in the range of 46-116mm in diameter was prepared. On the other hand, the coating solution was prepared by dissolving only 1.5% by weight of the cyanine dye as in Formula 5 in a solvent in which 5% by weight of ethylene glycol monomethyl ether acetone was added to 2,2,3,3-tetrafluoropropanol. It evaluated by the method similar to Example 1 using the said coating liquid.

Reflectance and reliability test results of the optical recording medium according to Examples 1 to 3 and Comparative Examples are summarized in Table 1 below.

Item 1 play (initial) 1 million playback 80 ° C., 80% RH, after 800 hours I _top ¹⁾ Example 1 Example 2 Example 3 0.670.690.67 0.670.690.67 0.670.690.68 Comparative example 0.66 - 0.60 I ₁₁ / I _top ²⁾ Example 1 Example 2 Example 3 0.700.680.71 0.690.680.71 0.720.690.72 Comparative example 0.71 ≤0.3 0.50 I ₃ / I _top ³⁾ Example 1 Example 2 Example 3 0.540.520.55 0.520.510.52 0.550.530.55 Comparative example 0.55 ≤0.3 0.40 1) I _top : highest signal value 2) I ₁₁ / I _top : modulation amplitude, I ₁₁ = 11T intensity (standard value 0.6 or more) 3) I ₃ / I _top : modulation amplitude, I ₃ = 3T Intensity (standard value 0.3 to 0.7)

As can be seen in Table 1, the optical recording mediums of Examples 1 to 3 prepared according to the present invention are significantly resistant to degradation of organic pigments compared to conventional comparative examples in which no oxidation resistance enhancer is used. It can be seen that the wettability is greatly improved by 10 to 40% or more, and thus the quality of the product is improved in terms of reliability.

As described above, the oxidation resistant optical recording medium according to the present invention has an effect of having excellent reliability characteristics by improving the durability and moisture resistance of the recording layer as compared with the conventional optical recording medium containing only organic dyes.

Claims (3)

An optical recording medium in which an organic dye recording layer, a reflective layer, and a protective layer are sequentially stacked on a substrate, wherein the recording layer contains 0.1 to 20% by weight of a cobalt compound-based oxidation resistance enhancer relative to the pigment in the overall composition of the organic dye recording layer. Oxidation resistant optical recording medium, characterized in that. The oxidation resistant optical recording medium according to claim 1, wherein the cobalt compound-based oxidation resistance improving agent is represented by the following Chemical Formula 1. Formula 1 In the above formula, A is Li ⁺ , Na ⁺ or Cs ⁺ m, n, l are each independently 0 or an integer of 1 to 10, DMF means N, N-dimethylformamide. The method of claim 1 or 2, wherein the oxidation resistance improving agent is spin-coated on a substrate in a coating liquid state by dissolving in a solution represented by the following formulas (3) and (4) together with an organic pigment containing a compound of formula (2) as a main component Oxidation resistant optical recording medium, characterized in that contained in the state. Formula 2 In the above formula, R ₁ , R ₂ , and R ₃ are each independently an alkyl group having ₁ to ₆ carbon atoms, n is an integer of 1 to 10, X is a halogen atom, perhalogenic acid, phosphorus 4-fluoro or toluene sulfonic acid, A is a ring substituent containing a benzene or naphthalene ring. Formula 3 Formula 4 Among the above formulas, R ₄ is CF ₃ , H or CF ₂ (H)-(CF ₂ ) _n −, where n is 1, 2, 3, 4 or 5, R ₅ , R ₆ , R ₇ and R ₈ are each independently -OH, -H, -CH ₃ , , Or C _n H _{2n + 1} -COO-, wherein m and n are each independently an integer of 1 to 4;