JPH02196689A - Optical recording medium - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an optical recording medium, and more specifically, an optical recording medium with a simple structure that allows recording with high sensitivity using a low-power laser. It is related to recording media.

[Prior Art] Many recording media using phthalocyanine derivatives in the recording layer have been known (Japanese Patent Laid-Open No. 139789/1989).
, JP-A-63-149189, JP-A-63-15829
4th prize).

However, these recording media perform recording by evaporating the recording layer with a high-energy beam such as a laser beam and forming holes in the recording layer. This method has the disadvantage that it is necessary to provide a space inside the recording medium, a so-called air incident structure, and the structure of the medium becomes complicated.

Furthermore, Japanese Patent Laid-Open No. 154098/1983 describes a recording medium that utilizes absorption changes based on changes in the crystal system of copper phthalocyanine and the like. However, these recording media had the disadvantage that the sensitivity was not very high because the activation energy required for crystal system change was relatively high.

[Problems to be Solved by the Invention] The present invention was devised in view of the current state of the prior art, and its purpose is to provide an optical recording medium with a simple structure and high sensitivity.

[Means for Solving the Problems] The object of the present invention is achieved by an optical recording medium characterized in that the recording layer contains copper phthalocyanine and at least one type of phthalocyanine compound other than the copper phthalocyanine.

That is, by incorporating other phthalocyanines other than the copper phthalocyanine into the copper phthalocyanine recording film, the other phthalocyanines enter the crystal lattice of the copper phthalocyanine, and the activation energy required for changing the crystal system is appropriately reduced. discovered that recording could be performed with high sensitivity using a low-power laser, leading to the present invention.

The recording principle in the optical recording medium of the present invention is based on a change in absorption due to a change in the crystal system of the recording layer, and the structure of the recording medium can be simplified.

The optical recording medium of the present invention can be obtained by forming a thin film of copper phthalocyanine containing at least one phthalocyanine compound other than copper phthalocyanine on a substrate and providing a recording layer thereon. If necessary, a reflective layer, a protective layer, etc. can be provided.

The phthalocyanine compound other than copper phthalocyanine contained in copper phthalocyanine may be any compound that facilitates the transition of the crystal system of copper phthalocyanine, such as metal-free phthalocyanine, cobalt phthalocyanine, vanadyl phthalocyanine, chloro Aluminum phthalocyanine, indium phthalocyanine, dichlorosilicon phthalocyanine, silver phthalocyanine, magnesium phthalocyanine, zinc phthalocyanine,
Examples include barium phthalocyanine, nickel phthalocyanine, titanium phthalocyanine, lead phthalocyanine, dichlorotin phthalocyanine, and derivatives of these phthalocyanines.

The reflective layer used in the optical recording medium of the present invention may be of any material as long as it sufficiently reflects the laser beam used for reading, and known metal thin films may be used. Examples of metals include aluminum, gold, silver, and copper.

The protective layer used in the optical recording medium of the present invention may be of any material as long as it can protect the recording layer physically or chemically, but the ease of forming the protective layer, etc. Various polymers are used. Polymers used include polyvinyl alcohol, polycaponate, polyacrylic ester, polymethacrylic ester, polyester, polystyrene, polyamide, and the like.

The method of incorporating a phthalocyanine compound other than copper phthalocyanine into copper phthalocyanine may be any method as long as both can be sufficiently mixed, and known methods such as simultaneous vapor deposition and solution mixing may be used. be able to. For example, a method may be used in which copper phthalocyanine and another phthalocyanine compound are simultaneously vapor-deposited from separate vapor deposition sources, or a method in which both phthalocyanines are dissolved in a solvent in which they are well soluble and then recrystallized.

As a method for providing the recording layer, a known method can be used, such as vapor deposition, solution spin code, bar code, etc. If necessary, the recording layer can be prepared by using a polymer as a binder and dispersing microcrystals of the phthalocyanine mixture used in the present invention.

The thickness of the recording layer is preferably from 50 nm to 5 μm, more preferably from 1100 nm to 1 μm.

The amount of phthalocyanine compounds other than copper phthalocyanine is
0 for copper phthalocyanine. The range is preferably 1 to 50% by weight, more preferably 0.5 to 10% by weight.

The substrate used in the present invention can be provided with a recording layer and may be made of any material as long as it has sufficient mechanical strength, such as glass, metal, polycarbonate, polymethacrylate, polyethylene, and polypropylene. , polyester, or paper.

[Example] EXAMPLES The present invention will be explained in more detail with reference to Examples below.

Example 1 Copper phthalocyanine (manufactured by Tokyo Kasei Kogyo Co., Ltd.) and cobalt phthalocyanine (manufactured by Tokyo Kasei Kogyo Co., Ltd.) were deposited on a glass substrate using a high vacuum evaporation device (manufactured by Nippon Shinku Gijutsu Co., Ltd.) and recorded. A layer was provided to obtain an optical recording medium. A molybdenum sublimation metal boat (manufactured by Nippon Pax Metal Co., Ltd.) was used as the vapor deposition boat. Copper phthalocyanine and cobalt phthalocyanine were placed in separate deposition boats, and 5x
Under reduced pressure of 10 Torr, a voltage was applied to each boat so that the current flowing through the boat was maintained at 100 A for the former and 85 A for the latter, and the deposition was carried out so that the proportion of cobalt phthalocyanine was 1% by weight. I did it. The thickness of the deposited film was monitored using a crystal film thickness meter (manufactured by Japan Vacuum Technology Co., Ltd.), and the thickness of the recording layer was adjusted to 150 nm.

Analysis of the obtained recording layer by ICP emission spectroscopy revealed that the atomic ratio was Cu/Co=100/1.

FIG. 1 shows the ultraviolet-visible absorption spectrum of the optical recording medium obtained as described above. Measurements are carried out using a UV-visible spectrophotometer (
(Newly manufactured by Hitachi).

This optical recording medium was irradiated with a 700 nm laser beam at a power of 1 mW for 20 nsec. As a result, the ultraviolet-visible absorption spectrum changed as shown in FIG. With this change, the transmittance at a wavelength of 720 nm decreased from 55% to 25%.
%. From this, it was found that recording could be read using a laser beam of 720 nrn.

Comparative Example 1 Only copper phthalocyanine was deposited on a glass substrate under the same conditions as in Example 1, and a recording layer with a thickness of 150 nm was provided to obtain an optical recording medium. FIG. 3 shows the ultraviolet-visible absorption spectrum of this optical recording medium.

The optical recording medium obtained as described above was irradiated with a 700 nm laser beam at a power of 1 mW for 20 ns eC.

FIG. 4 shows the ultraviolet-visible absorption spectrum of the irradiated area. It was found that the change in absorption was very small and recording could not be performed under these conditions.

[Effects of the Invention] Since the present invention makes it possible to form a very sensitive recording layer, it is possible to obtain an optical recording medium on which recording can be performed using a low-output laser. Since this recording medium performs recording by changing the absorption of the recording layer, it does not involve evaporation of the recording layer and can have a simple structure.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an ultraviolet-visible absorption spectrum of one example of the recording layer of the present invention, FIG. 2 is a diagram showing an ultraviolet-visible absorption spectrum after the recording layer is irradiated with a recording laser beam, and FIG. The figure shows the ultraviolet-visible absorption spectrum of the recording layer described in the comparative example, and FIG. 4 shows the ultraviolet-visible absorption spectrum after the recording layer described in the comparative example was irradiated with a recording laser beam. It is. 02

Claims (1)

[Claims] 1. An optical recording medium characterized in that a recording layer contains copper phthalocyanine and at least one type of phthalocyanine compound other than the copper phthalocyanine.