KR19980047025A - Optical record carrier containing epoxy resin - Google Patents

Abstract

The present invention relates to an optical recording medium containing an epoxy resin, and more particularly, in the construction of a recording layer in an optical recording medium by a heat mode in which a recording layer, a reflective layer, and a protective layer are laminated on a substrate. By newly adding and mixing a high-transparent epoxy resin with the organic dyes used in the prior art, the reflectance of the recording layer is increased by irradiation with laser light, so that the reflection layer can be configured at low cost, and the thermal conductivity is low, so that local heating is achieved. The present invention relates to a new optical recording medium which is not only suitable for high-density recording, but also excellent in durability and moisture resistance by a hardened structure, thereby improving reliability.

Description

Optical record carrier containing epoxy resin

The present invention relates to an optical recording medium containing an epoxy resin, and more particularly, in the construction of a recording layer in an optical recording medium by a heat mode in which a recording layer, a reflective layer, and a protective layer are laminated on a substrate. By newly adding and mixing a high-transparent epoxy resin with the organic dyes used in the prior art, the reflectance of the recording layer is increased by irradiation with laser light, so that the reflection layer can be configured at low cost, and the thermal conductivity is low, so that local heating is achieved. The present invention relates to a new optical recording medium which is not only suitable for high-density recording, but also excellent in durability and moisture resistance by a hardened structure, thereby improving reliability.

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). The WORM Type compact disc, which 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, wherein the recording layer is formed in a state where a groove portion and a 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 optical recording medium in which the conventional cyanine dye is used for the recording layer, since the reflectance is lower than that of other materials, there is an economic burden of using the reflective layer formed on the recording layer as expensive Au instead of the existing Al. In addition, the durability is relatively weak, and as the number of playbacks increases, the recording sensitivity is greatly decreased.

Therefore, in the present invention, in order to solve the problems in the conventional optical recording medium containing an organic dye, by using a new addition of a high-transparent epoxy resin to the organic dye, it is possible to record even in the use of a low concentration of the dye, thereby reflecting Instead of the expensive reflective layer Au, the existing low-cost Al allows sufficient reflection, and local heating is possible due to low conductivity, which improves high-density recording characteristics and improves thermal characteristics by hardening. By improving, the aim is to improve economics and reliability at the same time.

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 1 to 90 wt% of a high transparency epoxy resin in the overall composition of the organic dye recording layer. It features.

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 epoxy resin in addition to the organic dye. Such an epoxy resin has a high transparency that transmits rather than absorbs light due to the characteristics of the optical recording medium. It is preferable to use an epoxy resin having an increased reflectance, and for example, the following Chemical Formulas 1, 2 or mixtures thereof can be used.

Among the above formulas,

R ₁ and R ₂ are the same as or different from each other, and C ₁ to C ₁₀ alkyl group, C ₁ to C ₉ alkylcarboxyl or carbonyl group, C ₁ to C ₁₀ aryl group, C ₁ to C ₈ cycloalkyl group, halogen An atom, an amino group, a C ₁ to C ₇ alkoxy group or a hydroxy group,

n is an integer from 1 to 15.

The epoxy resin according to the present invention is used together with an organic dye mainly composed of the following compound of formula (3), which has been conventionally used, and when they are mixed together to form a coating liquid for forming a recording layer, the following formulas (4) and (5) The coating layer is formed by dissolving in a mixed solution or a single solution of the two solutions represented by and forming a coating layer by spin coating on a substrate.

In the above formula,

R ₃ , R ₄ and R ₅ are each independently C ₁ to C ₆ alkyl groups,

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 ₆ is CF ₃ , H or CF ₂ (H)-(CF ₂ ) _n -where n is 1, 2, 3, 4 or 5,

R ₇ , R ₈ , R ₉ and R ₁₀ are each independently —OH, —H, —CH ₃ , CH ₃ CO—,

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, and then continues. An optical recording medium is manufactured by forming the reflective layer 3 and the protective layer 4 in a conventional manner.

In this case, a conventional polycarbonate (PC), polymethyl methacrylate (PMMA), amorphous polyolefin (APO), etc. may be used, and the reflective layer may be Au, Ag, Cu, Al, etc. This is possible. In addition, the protective layer may be a conventional epoxy resin, acrylic resin, silicone resin, urethane resin and the like in a thickness of 0.1 to 100 ㎛ for the purpose of protecting against scratches.

On the other hand, the epoxy resin newly used in the present invention, when present with the conventional organic pigment in the recording layer as described above, and continuously irradiating strong power on the recording surface of the laser generates heat energy in the laser light irradiation unit due to a sudden temperature rise Thermal polymerization progressed and the reflectance of the laser light irradiation part caused a difference, and recording was performed. At this time, the content of the signal is determined by the bit length formed in the recording portion, and the quality of the reproduction signal is determined.

In more detail, in this reaction process, the epoxy resin may undergo a polymerization reaction by heat, thereby improving durability and moisture resistance by improving thermal properties by curing as compared with the case of using only conventional organic dyes.

In addition, since less dye can be used as the epoxy resin, the reflectance is increased.

According to the present invention, such an epoxy resin can be used in an amount of 1 to 90% by weight based on the dry weight of the composition constituting the entire recording layer. Preferably, it is effective when used in an amount of 10 to 65% by weight.

On the other hand, the recording layer containing the epoxy resin according to the present invention is spin-coated on a substrate with a thickness of 100 to 180 mm after drying. If the thickness is too thin or too thick after drying, the recording layer does not show a difference in reflectance and thus obtains a clean playback signal. It becomes impossible. Such a recording layer according to the present invention has an effect of improving the reflectance of 10 to 40% because it is possible to perform optical recording with excellent reproducibility even if the amount of organic dyes is reduced.

Therefore, even in the case of using an Al component instead of Au which is used for a recording layer composed of conventional organic dyes as a reflective layer, excellent recording and reproducing effects are exhibited.

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. Meanwhile, 1.0% by weight of a cyanine pigment as shown in Formula 6 and 5.0% by weight of an epoxy resin of Formula 7 were dissolved in a solvent in which 5% by weight of ethylene glycol monomethyl ether acetone was added to 2,2,3,3-tetrafluoropropanol. To prepare a coating solution.

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 about 400 to 500 GPa in the flat portion and the groove portion. When a reflective layer having a thickness of about 600 으로 with Al is deposited on the optical recording layer manufactured using a sputtering machine, and a protective layer having a thickness of about 3 μm is formed thereon by using an ultraviolet curable resin, the present invention. 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, 1.0% by weight of the cyanine dye as shown in Formula 8 and 10.0% by weight of the epoxy resin of Formula 9 were dissolved in a solvent in which 5% by weight of ethylene glycol monomethyl ether acetone was added to 2,2,3,3-tetrafluoropropanol. To prepare a coating solution. 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. Meanwhile, 1.0% by weight of the cyanine dye as shown in Formula 10 and 4.0% by weight of the epoxy resin of Formula 11 were dissolved in a solvent in which 5% by weight of ethylene glycol monomethyl ether acetone was added to 2,2,3,3-tetrafluoropropanol. To prepare a coating solution. It evaluated by the method similar to Example 1 using the said coating liquid.

Example 4

A coating solution was prepared in the same manner as in Example 1, but a coating solution was prepared using an epoxy resin of the following Formula 12 as an epoxy resin, and evaluated in the same manner as in Example 1.

Example 5

The coating solution was prepared in the same manner as in Example 2, but the coating solution was prepared using the epoxy resin of the following Chemical Formula 13 as a thermally decomposable resin, and the evaluation was performed in the same manner as in Example 1.

Example 6

A coating solution was prepared in the same manner as in Example 3, but the epoxy resin of Formula 14 was dissolved as an epoxy resin to prepare a coating solution, and the evaluation was performed in the same manner as in Example 1.

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 6 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 6 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 Example 4 Example 5 Example 6 0.650.650.640.670.690.67 0.650.650.640.670.690.67 0.650.650.640.670.690.68 Comparative example 0.56 - 0.45 I ₁₁ / I _top ²⁾ Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 0.670.670.680.700.680.71 0.680.670.680.690.680.71 0.670.670.680.720.690.72 Comparative example 0.60 ≤0.3 0.40 I ₃ / I _top ³⁾ Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 0.550.520.540.540.520.55 0.540.520.530.520.510.52 0.550.530.540.550.530.55 Comparative example 0.45 ≤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 from Table 1, the optical recording mediums of Examples 1 to 6 prepared according to the present invention have superior reflectance of the recording layer compared to the conventional comparative example without using a high-transparent epoxy resin, and thus have excellent recording characteristics during reproduction. It can be seen that the improvement is more than about 10%, and the durability and moisture resistance due to the curing structure of epoxy are improved, and the data left for 80 hours at 80 ° C. and 80% RH (Relative Humidity) environment shows great reliability. It can be seen from the above test results that the improvement was shown.

As described above, the optical recording medium containing the epoxy resin according to the present invention, compared with the conventional optical recording medium containing only organic dyes, realizes the economical efficiency of the reflective layer due to the increased reflectance of the recording layer and the improvement of the recording characteristics during reproduction as well as epoxy. Durability and moisture resistance improvement by the cured structure of the resin has the effect of having excellent properties in terms of reliability.

Claims (5)

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 1 to 90% by weight of an epoxy resin in the total composition of the organic dye recording layer. Containing optical recording medium. The optical recording medium according to claim 1, wherein the epoxy resin is a highly transparent epoxy resin. 3. The optical recording medium according to claim 2, wherein the highly transparent epoxy resin is represented by the following Chemical Formulas 1, 2 or a mixture thereof. Formula 1 Formula 2 Among the above formulas, R ₁ and R ₂ are the same as or different from each other, and C ₁ to C ₁₀ alkyl group, C ₁ to C ₉ alkylcarboxyl or carbonyl group, C ₁ to C ₁₀ aryl group, C ₁ to C ₈ cycloalkyl group, halogen An atom, an amino group, a C ₁ to C ₇ alkoxy group or a hydroxy group, n is an integer from 1 to 15. The method according to claim 1, wherein the epoxy resin is dissolved in a solution represented by the following formulas (4) and (5) together with an organic pigment containing a compound of formula (3) as a main component, and is contained in a spin-coated state on a substrate in a coating liquid state. An optical recording medium containing an epoxy resin, characterized in that. Formula 3 In the above formula, R ₃ , R ₄ and R ₅ are each independently C ₁ to C ₆ alkyl groups, 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 4 Formula 5 Among the above formulas, R ₆ is CF ₃ , H or CF ₂ (H)-(CF ₂ ) _n -where n is 1, 2, 3, 4 or 5, R ₇ , R ₈ , R ₉ and R ₁₀ are each independently —OH, —H, —CH ₃ , CH ₃ CO—, Or C _n H _{2n + 1} -COO-, wherein m and n are each independently an integer of 1 to 4; The optical recording medium containing an epoxy resin according to claim 1, wherein the reflective layer is formed of a conventional Al reflective layer.