JPH06231488A - Recordable optical disk - Google Patents

Abstract

PURPOSE:To considerably improve the corrosion resistance of a light reflecting layer and to inexpensively produce a high reliability long-lived recordable optical disk having reliability comparable to that of a disk using gold as the light reflecting layer, excellent in resistance to high temp. and humidity and hardly undergoing a change in the characteristics with the lapse of time. CONSTITUTION:When a light absorbing layer, a light reflecting layer made of silver or based on silver and a protective layer are successively laminated on a transparent substrate to obtain a recordable optical disk, one side of the light reflecting layer coming in contact with the protective layer is treated with a triazinethiol compd.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a recordable optical disc. For more information, the so-called compact disc (CD)
The present invention relates to an optical disc that is compatible with, and is suitable for a writable optical disc.

[0002]

2. Description of the Related Art Compact discs have a large recording capacity and high productivity as software packages, and thus have been widely used as audio software, computer game software, and electronic publishing media. However, in order to produce a compact disc, a die for transferring a record is required on the transparent substrate, and therefore, when producing about 100 discs or less, the cost per disc is low. It will be considerably higher.

In order to solve this problem, a compact disc having a recordable area which can be directly recorded on the disc, that is, a recordable compact disc has been developed, instead of manufacturing a recording disc through a mold. . A recordable compact disc is recordable and has the same reflectance as a read-only compact disc.
It has the feature that it can be played back by a compact disc player or drive for playback after recording.

This recordable compact disc is usually manufactured by sequentially providing a light absorbing layer made of an organic dye, a light reflecting layer made of a metal, and a protective layer made of an ultraviolet curable resin on a transparent substrate.

[0005]

In the recordable compact disc which has been put to practical use and is commercially available, the light reflecting layer has a high reflectance of 65% or more and a high corrosion resistance with respect to the wavelength of the reading laser beam. Although gold and an alloy containing gold as a main component are used to obtain gold, gold is expensive, which causes a big problem in terms of cost.

On the other hand, when a metal such as silver, copper or aluminum, which is inexpensive and has a high reflectance equivalent to that of gold, and an alloy containing them as a main component are used as the light reflecting layer, the light reflecting layer is corroded. It is difficult to manufacture a recordable compact disc with sufficient reliability in the usage environment because the disc characteristics such as a decrease in reflectance and an increase in errors are likely to change with time.

The present invention solves the above-mentioned conventional problems and uses a cheaper metal light reflecting layer without impairing the life and reliability of a recordable optical disc using expensive gold as a light reflecting layer. Therefore, it is an object of the present invention to provide a low-cost optical disc suitable for a recordable compact disc.

[0008]

As described above, when a metal such as silver, copper, aluminum or an alloy containing them as a main component is used as the light reflecting layer instead of gold having high corrosion resistance, Since the deterioration of the disk characteristics due to the corrosion of the light reflecting layer and the increase of errors are likely to occur,
As a result of earnest studies on the corrosion form of silver and the light reflection layer containing silver as a main component, the inventors of the present invention determined the extent of corrosion progress from the surface of the light reflection layer in contact with the protective layer, which determines the life of the entire disc. I came to obtain the knowledge.

Based on this finding, as a result of further studies on the above-mentioned prevention of corrosion, as a result, by treating the surface of the light-reflecting layer containing silver or silver as a main component with the protective layer in contact with the triazine thiol compound. It was found that a progress of corrosion of the light-reflecting layer was extremely suppressed and a recordable optical disc having a disc reliability equivalent to that when gold was used as the light-reflecting layer was obtained, and the present invention was completed.

That is, the gist of the present invention is, in a recordable optical disc in which a light absorption layer, a light reflection layer containing silver or silver as a main component, and a protection layer are sequentially laminated on a transparent substrate, the protection layer of the light reflection layer. A recordable optical disc is characterized in that the surface on the side in contact with is treated with a triazine thiol compound. The recordable optical disc of the present invention will be described in detail below.

Examples of the material of the transparent substrate used in the present invention include plastics such as polycarbonate, polymethylmethacrylate, and polyolefin, glass, or glass on which plastic is formed. These transparent substrates generally have a thickness of about 1 to 2 mm and spiral guide grooves are formed on the surface thereof. As the constituent material of the light absorbing layer formed on the transparent substrate, a light absorbing organic dye is preferably used, specifically, a cyanine dye, a squarylium dye, a pyrylium dye, a triarylamine dye, a metal-containing azo dye, Examples include phthalocyanine dyes. As a method of forming the light absorbing layer, a method of dissolving an organic dye in an organic solvent and spin-coating on the transparent substrate is usually used.

In the present invention, a thin film of silver or an alloy containing silver as a main component is used as the light reflecting layer. When an alloy containing silver as a main component is used as the light reflecting layer, it is not particularly limited as long as it has a high reflectance of 65% or more with respect to the wavelength of the reading laser light, but is preferably copper, gallium or aluminum. Alloys of two or more components of silver with palladium, rhodium, etc. are used. Further, a trace amount of an element such as tungsten, magnesium or boron may be added for the purpose of corrosion resistance.

The silver or metal thin film containing silver as a main component, which is the light reflecting layer, is usually formed by a sputtering method or a vacuum deposition method, and preferably has a thickness of 50 to 200 nm. Thus, the surface of the light reflecting layer formed on the transparent substrate is treated with a triazine thiol compound. As the triazine thiol compound, the compound represented by the following general formula [I] is preferable. General formula [I]
In, -R represents -SR ¹ or -NR ² R ^3,
R ¹ , R ² and R ³ represent a hydrogen atom or a hydrocarbon group.
Preferable examples of the hydrocarbon group include an alkyl group, an alkenyl group and an aryl group.

[0014]

[Chemical 1]

As a treatment method, a triazine thiol compound is usually dissolved in an alcohol solvent in an amount of 0.001 to 0.05% by weight, preferably 0.005 to 0.03% by weight, and spin-coated on the light reflecting layer. It is preferable to perform drying after coating or dip coating. further,
The treated surface may be washed with an alcohol solvent to remove excess triazine thiol compound remaining on the disk.

As the protective layer formed on the light-reflecting layer treated with the triazine thiol compound, a hard material such as urethane-based elastic material or acrylic UV-curable resin is usually used. It is preferable to use an ultraviolet curable resin of the system, and these protective layers are usually
After coating with a thickness of 2 to 20 μm by spin coating,
It is formed by being cured by ultraviolet irradiation or the like.

[0017]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to the following examples as long as the gist thereof is not exceeded. Example 1 As a transparent substrate, a recording groove having a meandering tracking groove for a compact recordable disk, having a diameter of 120 mm,
A polycarbonate substrate having a thickness of 1.2 mm was used.

The light-absorbing layer was prepared by dissolving the metal-containing azo dye represented by the following structural formula in methyl cellosolve in an amount of 2.2% by weight (weight with respect to the solvent), filtering it, and spin-coating it on the substrate. A film was formed. After applying the dye, drying was performed in an oven at 80 ° C. for 10 minutes in order to completely evaporate the solvent in the dye layer. The film thickness of the dye layer was selected to have a high reflectance and was set to 120 nm.

[0019]

[Chemical 2]

Next, a 100 nm thick silver layer was formed as a light reflecting layer on the light absorbing layer by a DC magnetron sputtering method in an argon gas. Then, a 0.02% by weight (solvent weight) methanol solution of the compound represented by the following structural formula was applied onto the light reflecting layer by a spin coating method, and then the excess compound represented by the following structural formula was washed. Then, methanol was dropped on the inner circumference of the disk and spun to wash it away.

[0021]

[Chemical 3]

Further, an ultraviolet curing agent SD-318 (manufactured by Dainippon Ink and Chemicals, Inc.) was applied on the surface-treated light-reflecting layer in a thickness of 3 μm by a spin coating method, and ultraviolet rays were irradiated by an ultraviolet irradiation device. And cured to form a protective layer. About the obtained recordable compact disc, D
EFM signals were recorded with DU-1000 (Pulstec), and after a high temperature and high humidity test for 500 hours at a temperature of 85 ° C and a humidity of 85%, they were reproduced with a commercially available CD player to check for changes in C1 error. The measurement shows a slight C1
Only an increase in error was seen. The results are shown in Table-1. Example 2 A recordable compact disc was prepared in the same manner as in Example 1 except that a 100 nm thick silver-aluminum alloy (silver: 80 atom%, aluminum: 20 atom%) layer was formed as the light reflecting layer. It was

When the obtained disc was tested in the same manner as in Example 1, a slight increase in C1 error was observed. The results are shown in Table-1. Example 3 Example 1 was repeated except that a compound represented by the following structural formula was used in place of the compound represented by the above structural formula as the triazine thiol compound used for the surface treatment of the light reflecting layer.
A recordable compact disc was prepared in the same manner as in.

[0024]

[Chemical 4]

When the obtained disk was tested in the same manner as in Example 1, a slight increase in C1 error was observed. The results are shown in Table-1. Comparative Example 1 A recordable compact disc was produced in the same manner as in Example 1 except that the surface of the light reflecting layer was not treated with the triazine thiol compound.

When the obtained disk was tested in the same manner as in Example 1, a huge increase in C1 error was observed. The results are shown in Table-1. Comparative Example 2 A recordable compact disc was prepared in the same manner as Comparative Example 1 except that a 100 nm thick silver-aluminum alloy (silver: 80 atom%, aluminum: 20 atom%) layer was formed as the light reflection layer. It was

When the obtained disk was tested in the same manner as in Example 1, a huge increase in C1 error was observed. The results are shown in Table-1. Reference Example 1 A recordable compact disc was produced in the same manner as in Comparative Example 1 except that a gold layer having a thickness of 100 nm was formed as a light reflecting layer.

When the obtained disk was tested in the same manner as in Example 1, a slight increase in C1 error was observed. The results are shown in Table-1. Reference Example 2 A recordable compact disc was produced in the same manner as in Example 1 except that a gold layer having a thickness of 100 nm was formed as the light reflecting layer.

When the obtained disk was tested in the same manner as in Example 1, a slight increase in C1 error was observed. The results are shown in Table-1.

[0030]

[Table 1] The following is clear from Table-1.

In Comparative Examples 1 and 2, a large increase in C1 error due to corrosion of the light reflecting layer was observed after the high temperature and high humidity test. On the other hand, in Examples 1 to 3, the increase in C1 error was small even after the high temperature and high humidity test, and the disk reliability was the same as in Reference Examples 1 and 2 in which the gold layer was used as the light reflecting layer. Has been obtained.

[0032]

The recordable optical disc of the present invention comprises a light absorbing layer, a light reflecting layer containing silver or silver as a main component, and a protective layer, which are sequentially laminated on a transparent substrate. By treating the surface on the side in contact with the protective layer with a triazine thiol-based compound, the corrosion resistance of the light reflecting layer is significantly improved, and the disc reliability is equivalent to that when gold is used as the light reflecting layer. Therefore, it is possible to manufacture a recordable optical disc which has excellent resistance to high temperature and high humidity and has little change in characteristics over time, which is highly reliable and has a long life, at low cost.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Satoru Imamura 1000, Kamoshida-cho, Midori-ku, Yokohama-shi, Kanagawa Sanryo Kasei Co., Ltd.

Claims (1)

[Claims] 1. A recordable optical disc comprising a transparent substrate, a light absorbing layer, a silver or a light reflecting layer containing silver as a main component, and a protective layer, which are laminated in this order on a surface of the light reflecting layer in contact with the protective layer. A recordable optical disc treated with a triazine thiol compound.