KR19990074901A - Optical recording media - Google Patents

Abstract

The present invention relates to an optical recording medium. In the optical recording medium, a recording layer, a reflective layer, and a protective layer are sequentially formed on a transparent substrate on which a tracking groove is formed. The recording layer includes a cyanine dye and a stabilizer of Formula 1, and the reflective layer is silver or silver It is characterized by containing an alloy.

In the above formula, Y ₁ , Y ₂ , Y ₃ , Y ₄ , Y ₅ , Y ₆ , Y ₇ , Y ₈ , Y ₉ , Y ₁₀ , Y ₁₁ and Y ₁₂ are independently of each other hydrogen, halogen atom, halide Is selected from the group consisting of a nitro group and a cyano group, R ₁ and R ₂ are each independently an alkyl group having 1 to 8 carbon atoms, R ₃ is selected from the group consisting of hydrogen and an alkyl group having 1 to 8 carbon atoms, and ^- is ClO ₄ ^- is selected from the group consisting of ^{_{-, PF 6 -, C 6}} H 5 SO 3 - and _{p-CH 3 C 6 H 5} SO 3. In the optical recording medium of the present invention, the decomposition of the cyanine pigment is reduced as compared with other pigments using silver reflecting films, thereby improving not only the storage stability of the recording but also the manufacturing cost.

Description

Optical recording media

The present invention relates to an optical recording medium, and more particularly, to an optical recording medium that can be written once.

The organic optical recording medium is classified into a write once read many (WORM) that can be written only once depending on whether it can be erased and a rewritable (RW) that can be erased and rewritten after recording.

At present, the disk type is practically used as the optical recording medium of the WORM type. In particular, the fields of data storage discs, recordable audio CDs, photo CDs and the like have been advanced considerably. In order for the optical recording medium to be compatible with CD, it is required not only to have high reflectance and excellent carrier-to-noise ratio (CNR) characteristics, but also to have recording storage stability and high recording sensitivity. As such an optical recording medium compatible with CD, a compact disc (React Disc-Recordable) (CD-R) is known. The optical recording medium is manufactured by coating an organic dye capable of absorbing light on a transparent substrate to form a recording layer, and then forming a reflective layer thereon. Such an optical recording medium has advantages in terms of economy and productivity compared to an optical recording medium using a metal thin film as a recording layer.

A cyanine dye may be used as the organic dye for forming the recording layer. Here, the cyanine pigment refers to a dye having a cationic structure in which two nitrogen-containing heterocycles are bonded as -CH = or a chain thereof. As the material for forming the reflective layer, gold, silver, aluminum, copper and the like are known. Among them, gold is most suitable as a material for forming a reflective layer, but it is not preferable in terms of economy. In the case where aluminum is used as the material for forming the reflective layer, the reflectance characteristics are poor, thereby reducing the compatibility of the optical recording medium. In addition, when copper is used as the material for forming the reflective layer, there is a problem in that the durability of the optical recording medium is reduced.

On the other hand, the use of silver as a material for forming the reflective layer has an advantage compared to the case of using gold in terms of economical efficiency, but the cyanine dye is decomposed due to the reactivity of the silver and the cyanine pigment to increase the block error rate and jitter value. Not only does the EFM signal characteristics deteriorate, but serious loss of some of the recorded information arises. In order to solve this problem, a method of using an expensive special cyanine dye having a low reactivity with silver has been proposed as a recording layer forming material. However, this method is also practically impossible to use because it increases the manufacturing cost of the optical recording medium.

In order to solve the above problems, the present inventors have completed the present invention of an optical recording medium employing a recording layer containing a low-cost cyanine dye as well as a decrease in reactivity with silver.

SUMMARY OF THE INVENTION The present invention has been made in an effort to provide an optical recording medium having improved storage stability and reduced manufacturing cost.

In order to achieve the above object, in the present invention, in the optical recording medium in which the recording layer, the reflective layer and the protective layer are sequentially formed on a transparent substrate having a tracking groove,

The recording layer includes a cyanine dye and a stabilizer of formula (1),

An optical recording medium is provided, wherein the reflective layer contains silver or a silver alloy.

[Formula 1]

In the above formula, Y ₁ , Y ₂ , Y ₃ , Y ₄ , Y ₅ , Y ₆ , Y ₇ , Y ₈ , Y ₉ , Y ₁₀ , Y ₁₁ and Y ₁₂ are independently of each other hydrogen, halogen atom, halide , Nitro group and cyano group,

R ₁ and R ₂ are each independently an alkyl group having 1 to 8 carbon atoms,

R ₃ is selected from the group consisting of hydrogen and an alkyl group having 1 to 8 carbon atoms,

X ^- is selected from the group consisting of ^- is _{^{ClO 4 -, PF 6 -,}} C 6 H 5 SO 3 - and _{p-CH 3 C 6 H 5} SO 3.

The recording layer may further include a stabilizer in addition to the cyanine dye of the formula (1). At this time, the thickness of the recording layer is preferably 100 to 250 nm.

It is preferable that the mixing weight ratio of the stabilizer and the cyanine-based dye of Formula 1 is 3: 100 to 15: 100, and the stability of the cyanine-based dye is most excellent in this range. Here, the stabilizer is a singlet oxygen quencher. Any material commonly used as a stabilizer as an oxygen quencher can be used.

It is preferable that the depth of the tracking groove of the transparent substrate is 180 to 250 nm, and the width of the groove bottom is 250 to 450 nm.

The optical recording medium of the present invention is characterized in that the recording layer contains a cyanine dye of the formula (1), and the reflective layer contains silver or a negative alloy. The cyanine-based pigment of the formula (1) is very excellent in stability due to less reactivity with silver.

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

<Example 1>

Trifluoropropanol solution of 3% by weight of the compound of formula (2) in the center of an injection-molded polycarbonate resin substrate having a spiral guide groove (220 mm in depth, 350 mm in width, and 1.6 μm in pitch) having a thickness of 1.2 mm and an outer diameter of 120 mm After dropping, the substrate was rotated for 10 seconds at a speed of 1500 rpm. Subsequently, the substrate was dried at 70 ° C. for 2 hours to form a recording layer.

Silver was sputtered on the recording layer to form a reflective layer having a thickness of 60 nm. The optical disc was completed by spin-coating SK 7100 (Sony Chemical Co., Ltd.) which is an ultraviolet curable resin on top of this reflective layer, and then irradiating with ultraviolet rays to form a protective layer.

<Example 2>

An optical disc was completed in the same manner as in Example 1, except that the compound of Formula 3 was used instead of the compound of Formula 2.

Comparative Example 1

An optical disc was completed in the same manner as in Example 1, except that a mixture of the compound of Formula 3 and the compound of Formula 4 in a 4: 6 weight ratio was used instead of the compound of Formula 2.

Comparative Example 2

An optical disc was completed in the same manner as in Example 1, except that a mixture of the compound of Formula 3 and the compound of Formula 5 in a 4: 6 weight ratio was used instead of the compound of Formula 2.

Comparative Example 3

An optical disc was completed in the same manner as in Example 1, except that the compound of Formula 6 was used instead of the compound of Formula 2.

Placing the optical disk manufactured according to Example 1-2 and Comparative Example 1-3 on a turntable and rotating at a linear speed of 1.4 m / s using a drive having an optical head mounted with a semiconductor laser having an oscillation wavelength of 785 nm The beam was controlled to pass through the resin substrate and to be connected to the recording layer on the guide groove. At the same time, the EFM modulated signal was recorded on the recording layer in accordance with the method commonly used in compact discs with a laser output of 6-12 mW.

Thereafter, the optical disk was allowed to stand for 72 hours at 70 ° C. and 80% humidity. The environmental resistance characteristics were evaluated by comparing the change, jitter, and block error rate of the EFM modulated signal before and after 72 hours, and the results are shown in Table 1 below.

division EFM modulated signal (I ₃ / I _top ) Jitter (ns) Block error rate (%) 3T feet 3T Rand Example 1 I'm 0.515 21.5 24.1 0.12 after 0.467 19.3 21.6 0.20 Example 2 I'm 0.415 30.1 37.2 0.35 after 0.376 28.5 35.1 0.40 Comparative Example 1 I'm 0.348 33.4 22.0 0.35 after Not measurable Not measurable Not measurable Not measurable Comparative Example 2 I'm 0.427 29.5 27.6 0.10 after 0.350 26.6 27.2 0.70 Comparative Example 3 I'm 0.507 28.4 32.9 0.38 after 0.467 28.4 33.8 1.10

From Table 1, it can be seen that the optical disk manufactured according to Example 1-2 has significantly improved EFM modulated signal, jitter and block error rate characteristics after the environmental test, compared to the optical disk manufactured according to Comparative Example 1. there was. In addition, it was found that the block error rate characteristic was improved compared to the optical disk manufactured according to Comparative Example 2-3.

The optical recording medium of the present invention uses the cyanine dye of the formula (1) as the recording layer forming material and silver as the reflective layer forming material. Such an optical recording medium reduces the decomposition of the cyanine pigment as compared with the conventional optical recording medium, thereby improving not only the storage stability of the recording but also the manufacturing cost.

Claims (5)

In an optical recording medium in which a recording layer, a reflective layer and a protective layer are sequentially formed on a transparent substrate on which a tracking groove is formed, The recording layer includes a cyanine dye and a stabilizer of formula (1), And the reflective layer comprises silver or a silver alloy. <Formula 1> In the above formula, Y ₁ , Y ₂ , Y ₃ , Y ₄ , Y ₅ , Y ₆ , Y ₇ , Y ₈ , Y ₉ , Y ₁₀ , Y ₁₁ and Y ₁₂ are independently of each other hydrogen, halogen atom, halide , Nitro group and cyano group, R ₁ and R ₂ are each independently an alkyl group having 1 to 8 carbon atoms, R ₃ is selected from the group consisting of hydrogen and an alkyl group having 1 to 8 carbon atoms, X ^- is selected from the group consisting of ^- is ^{_{ClO 4 -, PF 6 -,}} C 6 H 5 SO 3 - and _{p-CH 3 C 6 H 5} SO 3. The optical recording medium according to claim 1, wherein the stabilizer is a singlet oxygen quencher. The optical recording medium of claim 1, wherein a mixing weight ratio of the stabilizer and the cyanine compound of Formula 1 is 3: 100 to 15: 100. The optical recording medium according to claim 1, wherein the tracking groove has a depth of 180 to 250 nm and a groove bottom having a width of 250 to 450 nm. The optical recording medium according to claim 1, wherein the recording layer has a thickness of 100 to 250 nm.