JPH09245373A - Optical recording medium - Google Patents

Abstract

(57) Abstract: A so-called writable compact disc in an optical recording medium in which a light absorbing layer containing an organic dye, a light reflecting layer and a protective layer are sequentially laminated on a transparent substrate. An optical recording medium, wherein the light reflecting layer contains silver as a main component and contains at least 3 to 20% by weight of indium. [Effect] It is possible to provide a high-reliability optical recording medium having high temperature and high humidity resistance and excellent light resistance at low cost.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an optical recording medium. More specifically, it relates to a so-called compact disc-compatible and writable optical disc, that is, to a highly reliable and inexpensive optical disc having excellent light resistance, high temperature resistance and high humidity resistance.

[0002]

2. Description of the Related Art An optical recording medium represented by a compact disc has a large recording capacity and high productivity as a software package, and thus has been widely used as a medium for audio software, computer software and electronic publishing. There is. In order to manufacture a read-only optical recording medium represented by a conventional compact disc, a mold for transferring a record on the transparent substrate is required.
However, since the cost of manufacturing the mold is high, the cost per disk becomes considerably high when manufacturing several hundreds of disks.

In order to solve this problem, an optical recording medium having a recordable area that can be directly recorded on the disc, that is, a compact disc recordable ( Below, C
An optical recording medium which can be recorded by a laser beam known as D-R) has been developed. Hereinafter, the CD-R will be described as an example. The CD-R is recordable and has the same reflectivity as a read-only compact disc, so it can record information and can be played and read by a read-only compact disc player or a read-only compact disc drive. It has the characteristic of being. Usually, a recordable optical recording medium represented by CD-R has 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, which are sequentially laminated on a transparent substrate. It is produced by

[0004]

DISCLOSURE OF INVENTION Problems to be Solved by the Invention In a CD-R which has been put to practical use and is commercially available, it is possible to obtain a high reflectance of 65% or more with respect to a laser beam having a wavelength of 780 nm for reading, and migration of a light reflecting layer In order to prevent the decrease in reflectance due to chemical reactions and chemical reactions, stable gold and alloys containing gold as the main component are used as the light-reflecting layer. It is an obstacle to the above. On the other hand, in order to reduce the manufacturing cost, silver, aluminum, which has a reflectance similar to gold,
When a metal such as copper or an alloy containing them as a main component is used as the light reflecting layer, the disc characteristics such as a decrease in reflectance and an increase in error due to migration or a chemical reaction tend to occur over a long period of time. It was difficult to produce a highly reliable CD-R that can withstand storage. Further, it is effective to add gold or a platinum group in order to stabilize silver, but this method loses the meaning of manufacturing at low cost.

On the other hand, it has been proposed to use a corrosion resistant alloy such as stainless steel for the purpose of improving the corrosion resistance, but most of them require a large amount of an additive component for exhibiting the corrosion resistance. Therefore, the reflectance of the alloy is low. Moreover, since the anticorrosion mechanism forms a non-conductive film on the surface of the alloy, when used as a reflective film, a decrease in reflectance cannot be avoided. Further, when gold is used, the reflectance decreases as the wavelength of the laser light currently used for recording and reading becomes shorter than 780 nm. Therefore, in the optical recording medium, which is expected to be put to practical use in the future and has a higher recording density than the current CD-R, it is expected that a laser for recording and reading of a shorter wavelength will be used than the present. In addition, it is not always preferable to use gold as the reflective layer, and it is preferable to use as the reflective layer a metal having a high reflectance over the entire visible light region, such as silver or aluminum.

[0006]

The present invention has been invented in view of the above-mentioned prior art, and has durability and reliability equivalent to those of an optical recording medium using gold having a high stability as a light reflecting layer. While maintaining the above, by making it possible to use silver, which is cheaper than gold, as the light-reflecting layer, it is possible to manufacture a recordable optical recording medium at low cost and improve the light reflectance in a wider wavelength range. It is an object to provide an optical disc compatible with high density recording.

The inventors of the present invention have made extensive studies on the above-mentioned problems. As a result, in an optical recording medium comprising a light absorbing layer containing an organic dye and a metal reflecting layer on a transparent substrate, silver is mainly used as the metal reflecting layer, By using an alloy layer containing at least 3 to 20% by weight of indium, it is possible to produce a recordable optical recording medium having a high reflectance in a wide wavelength range and having excellent light resistance and wet heat resistance. The present invention has been completed and the present invention has been completed.

That is, the present invention provides an optical recording medium in which a light absorbing layer containing an organic dye, a light reflecting layer and a protective layer are sequentially laminated on a transparent substrate, the light reflecting layer containing silver as a main component, The present invention relates to an optical recording medium containing at least 3 to 20% by weight of indium.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Materials for the transparent substrate used in the present invention include polycarbonate, polymethylmethacrylate,
A material having a high light transmittance with respect to visible light, such as plastic such as amorphous polyolefin or glass, can be preferably used. As these transparent substrates, those having a guide groove formed in a concentric circular shape or a spiral shape with a thickness of about 1 to 2 mm are usually used.

As the material of the light absorbing layer, as is well known,
The phthalocyanine-based dye, the naphthalocyanine-based dye, the cyanine-based dye, which are organic dyes without particular limitation,
Suitable are squarylium dyes, croconium dyes, azurenium dyes, triarylamine dyes, anthraquinone dyes, metal-containing azo dyes, dithiol metal complex dyes, indoaniline metal complex dyes, intermolecular CT dyes, These dyes may be used alone or in combination of two or more. Those skilled in the art will understand that, usually, these dye materials are used by adding a deterioration inhibitor, a binder and the like. Specific examples of phthalocyanine dyes include dyes described in JP-A-3-62877, JP-A-3-141582, and JP-A-3-215466.

As a method for forming a light absorbing layer containing an organic dye, a method in which an organic dye is dissolved in an organic solvent and spin-coated directly or through another layer on a transparent substrate can be preferably used. . The film thickness of the light absorption layer is the wavelength used, the optical constant of the reflective layer, in consideration of the recording sensitivity performance coefficient for the power of recording light such as laser light used for recording.
It is easily understood by those skilled in the art that it is appropriately selected depending on the material of the light absorption layer, and usually 10 nm to 5 μm.
m. The thickness of the light absorption layer is adjusted by appropriately changing the concentration of a liquid in which an organic dye is dissolved in an organic solvent in spin coating, the number of rotations in spin coating, or the like. Those skilled in the art will understand that the power can be easily adjusted by appropriately changing the power during vapor deposition. The light absorption layer may be provided on one side or both sides of the transparent substrate.

For the light reflecting layer, a metal layer containing silver as a main component and containing at least 3 to 20% by weight of indium is used. This improves wet heat resistance and light resistance as compared with the case where silver is used alone. The amount of indium added is preferably 3 to 20% by weight, more preferably 3 to 10% by weight. The composition can be easily confirmed by a fluorescent X-ray analysis method. The analysis in the depth direction in the case of forming a film can also be determined by Auger electron spectroscopy using a sputtering method or the like. The light reflection layer is directly on the light absorption layer or through another layer, a sputtering method,
It is preferable to form a polycrystalline film having a film thickness of 50 to 200 nm, which is formed by a vacuum evaporation method.

In forming the alloy by the sputtering method, sputtering is performed using the alloy as the target. In general, the composition of the target and the composition of the formed film do not always completely match due to the causes of segregation, selective sputtering, errors on measuring equipment, etc., but the difference between the composition of the target and the composition of the film is It does not have a big impact. Further, if necessary, the surface of the light reflection layer may be surface-treated with a tridianthiol compound or a benzimidazole compound. For the protective layer formed on the light reflection layer, it is preferable to use a hard material such as an acrylic ultraviolet curing resin. Usually, the thickness of 2 to 2 is directly formed on the light reflecting layer or through another layer by a spin coating method.
After being applied with a thickness of 0 μm, it is formed by curing with ultraviolet irradiation.

[0014]

EXAMPLES The present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples without departing from the scope of the invention. Example 1 As a transparent substrate, a polycarbonate substrate having a diameter of 120 mm and a thickness of 1.2 mm provided with a wobbling tracking groove for a recordable Kimpact disk was used. The light absorbing layer contains a phthalocyanine dye, that is, one at each α-position of each of the four benzene rings constituting phthalocyanine.
P having one 1-isopropyl-isoamyloxy group
A solution of 3.5% by weight dimethylcyclohexane of d-phthalocyanine was applied to a polycarbonate resin substrate (a disk having a diameter of 120 mmφ and a thickness of 1.2 mm) having a guide groove.
Spin coat at 0 rpm and dry for 2 hours at 70 ° C.
A light absorption layer having a film thickness of 00 nm was formed.

On the light absorption layer, 3.2% of indium was placed in a Balzers sputtering device (CDI-900).
A silver-indium alloy target containing a large amount of silver was attached, and a silver-based main body and a metal layer were sputtered to 100 nm to form a light-reflecting layer. When the composition of this light reflecting layer was analyzed by fluorescent X-ray, it was found to be 96.6% by weight of silver and 3.4% by weight of indium. Further, an ultraviolet curable resin SD-17 (manufactured by Dainippon Ink and Chemicals, Inc.) was spin-coated on the reflective layer, and then irradiated with ultraviolet rays to form a protective layer having a thickness of 6 μm, to prepare an optical recording medium.

This optical recording medium is equipped with a 780 nm semiconductor laser head and manufactured by Philips writer (CDD
-521) was used to record the EFM signal at a linear velocity of 2.8 m / s and a laser power of 9.5 mW. About the obtained optical recording medium, the temperature is 85 ° C and the humidity is 85%.
A high temperature and high humidity test was performed for 0 hours, and 5 sun (500
A light irradiation test of mW / cm ² ) was performed at 60 ° C. for 100 hours, and changes in reflectance and C1 error before and after the test were measured. As a result, a slight decrease in reflectance and an increase in C1 error were observed both after the high temperature and high humidity test and after the light irradiation test. Table 1 shows the results.

Example 2 An optical recording medium was produced by the same procedure as in Example 1 except that an alloy containing 10.5% by weight of indium was used as the target of the sputtering apparatus for forming the light reflecting layer. When the composition of the light reflecting layer was analyzed by fluorescent X-ray, silver 8
It was 9.2% by weight and indium 10.8% by weight. Furthermore, when this optical recording medium was evaluated in the same manner as in Example 1, only a slight decrease in reflectance and an increase in C1 error were observed. Table 1 shows the results.

Example 3 An optical recording medium was produced in the same procedure as in Example 1 except that an alloy containing 19.5% by weight of indium was used as the target of the sputtering apparatus for forming the light reflecting layer. When the composition of the light reflecting layer was analyzed by fluorescent X-ray, silver 8
It was 0.1% by weight and 19.9% by weight of indium. Furthermore, when this optical recording medium was evaluated in the same manner as in Example 1, only a slight decrease in reflectance and an increase in C1 error were observed. Table 1 shows the results.

Comparative Example 1 An optical recording medium was produced by the same procedure as in Example 1 except that an alloy containing 1.8% by weight of indium was used as the target of the sputtering apparatus for forming the light reflecting layer. When the composition of the light reflecting layer was analyzed by fluorescent X-ray, it was found that silver 87.
It was 8% by weight and indium was 2.2% by weight. further,
When this optical recording medium was evaluated in the same manner as in Example 1, a remarkable decrease in reflectance and a large increase in C1 error were observed. Table 1 shows the results.

Comparative Example 2 An optical recording medium was prepared by the same procedure as in Example 1 except that an alloy containing 30.2% by weight of indium was used as the target of the sputtering apparatus for forming the light reflecting layer. When the composition of the light reflecting layer was analyzed by fluorescent X-ray, silver 6
It was 9.5% by weight and indium 30.5% by weight. Further, when this optical recording medium was evaluated in the same manner as in Example 1, the reflectance was less than 65%, which did not satisfy the characteristics required for CD compatibility.

[0021]

[Table 1]

The following is clear from Table 1. That is, from Examples 1 to 3, at least 3
It is found that the characteristics of the optical recording medium having the light reflection layer mainly containing silver of 20 wt% are not deteriorated even after the high temperature and high humidity test, and the characteristics are not deteriorated even after the light irradiation test. . Further, when the content of indium is not sufficiently high, the reflectance is high at the initial stage, but the characteristics are significantly deteriorated both after the high temperature and high humidity test and after the light irradiation test. On the other hand, if the indium content is too high, it is stable after the high temperature and high humidity test and the light irradiation test, but it is found that the initial reflectance does not reach the required 65% for CD compatibility.

[0023]

Industrial Applicability According to the present invention, a highly reliable optical recording medium excellent in high temperature and high humidity resistance and excellent in light resistance can be manufactured at low cost, which is an industrially extremely useful invention. I have to say.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Nobuhiro Fukuda 1190 Kasama-cho, Sakae-ku, Yokohama-shi, Kanagawa Mitsui Toatsu Chemical Co., Ltd.

Claims (1)

[Claims] 1. An optical recording medium in which a light absorbing layer containing an organic dye, a light reflecting layer and a protective layer are sequentially laminated on a transparent substrate, the light reflecting layer containing silver as a main component and at least indium containing 3 An optical recording medium, characterized in that the content is up to 20% by weight.