JPH0821177B2 - Optical information recording medium - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a recording medium used in, for example, an optical disk recording / reproducing apparatus, particularly an optical type in which information can be written by using laser light and the written information can be read by using laser light. The present invention relates to an information recording medium.

BACKGROUND ART Conventionally, an optical recording / reproducing system using a method of recording and reproducing information such as video and audio using an optical information recording medium having a recording layer sensitive to laser light is well known. Thus, the conventional optical information recording medium has a structure in which a single recording layer is formed on the substrate.

However, it has become clear that it is difficult to obtain a recording layer having good photosensitivity to a laser beam having a constant wavelength by using a single photosensitive material, and two or more kinds of photosensitive materials are mixed to form a recording layer. It is considered to form. However, in order to form a recording layer composed of two or more kinds of photosensitive materials, it is necessary to obtain a solution using a solvent compatible with the desired two kinds of photosensitive materials and spin coat the solution. Furthermore, it is necessary to consider the condition that the solvent does not adversely affect the substrate such as dissolution or swelling, and there are severe restrictions on the combination of the photosensitive material and the solvent, and the degree of freedom in selecting the photosensitive material is narrow. There was a problem of becoming.

As a solution to this restriction, a dye thin film having a different molecular skeleton is laminated on a substrate (Japanese Patent Laid-Open No. 60-14739).
No. 1; Prior art 1) and one in which a dye thin film having the same molecular skeleton is laminated on a substrate (Japanese Patent Laid-Open No. 63-252791; Prior art 2) have been proposed.

However, Prior Art 1 utilizes the fact that the solubilities of dyes in solvents are different. That is, specifically, a solution in which the dye A, which is soluble in the solvent a but insoluble in the solvent b, is dissolved in the solvent a, is coated on the substrate, and then insoluble in the solvent a but not in the solvent b. A solution of soluble dye B in solvent b is coated on the thin film of dye A to give dye A /
The laminated thin film of B was formed on the substrate. Therefore, this technique has a drawback in that dyes having similar solubility in a solvent cannot be laminated.

On the other hand, Prior Art 2 discloses an information recording medium in which two information recording medium units containing an azurenium dye are bonded together. This technology proposes to bond two information recording medium units because there is no good method to prevent dye elution during multilayer coating, and the process is complicated and the productivity is poor and the cost is high. There was a drawback that

SUMMARY OF THE INVENTION [Object of the Invention] It is an object of the present invention to provide an inexpensive optical information recording medium with high production efficiency even when a dye having a similar molecular skeleton and a similar solubility in a solvent is used. .

[Structure of the Invention] The optical information recording medium of the present invention is an optical information recording medium having a plurality of dye recording layers laminated on a transparent substrate and each containing a dye, and the adjacent dye layers. Is characterized by comprising a polymer insoluble in different solvents and a dye dispersed in the polymer.

[Effect of the Invention] According to the present invention, a dye is dispersed in a plurality of polymers having different solubilities, and by laminating these polymers, even if a dye having a similar solubility to a solvent is used, Since the dye is fixed in the polymer when the coating layer is laminated, the dye does not elute from the dye thin film previously formed during the next coating. Therefore, the productivity of the optical information recording medium is improved and the cost is reduced.

Embodiment An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view of an optical information recording medium according to the present invention. That is, the substrate 1 is made of glass, acrylic resin,
It is made of a material having excellent light-transmitting property or light-reflecting property such as vinyl resin, polyether resin, epoxy resin, polycarbonate resin, polybutyral resin, cellulose acetate butyrate resin, and nitrocellulose resin. The first recording layer 2 is a thin film layer containing a dye that records data in response to irradiation light, which is thinned and formed on the substrate 1 by a spin coating method. The second recording layer 3 is a thin film layer containing a dye that records data in response to irradiation light having a light energy different from that of the irradiation light formed on the recording layer 2 by a spin coating method. The third recording layer 4 is the recording layer 3
It is a thin film layer containing the same dye as the recording layer 2 formed on the above.

In the process of forming the plurality of recording layers 2, 3 and 4, they are sequentially laminated on the substrate 1. That is, in the present invention, for example, a liquid in which a dye is dispersed or dissolved in a methanol solution of polyvinyl alcohol that is soluble in methanol but insoluble in acetone is spin-coated on the substrate 1, and the recording layer is formed after evaporation and drying of methanol. Then, a solution in which the dye is dispersed or dissolved in an acetone solution of polyvinyl chloride, which has a different solubility characteristic from the polymer of the recording layer 2 and is insoluble in methanol but soluble in acetone, is spin-coated The recording layer 3 is formed after evaporation and drying. Then, the recording layer 4 is formed by the same method as the recording layer 2. As described above, since the recording layers adjacent to each other on the laminated surface are formed by the spin coating method in which polymers having different solubility characteristics are dissolved by different solvents, the recording layers adjacent to each other are not affected, and thus, for example, methanol and It is also possible to form a laminated thin film with a dye having a similar solubility and structure that is soluble in both acetone.

As a typical example of a combination of such polymers having different solubilities in a solvent and applicable to the recording layer of the optical information recording medium of the present invention, combination I 1st layer: polyurethane (acetone solution) 2nd layer: Nitrocellulose, polymethylmethacrylate,
Polyvinyl acetate (diacetone alcohol solution) Combination II 1st layer: Polyvinyl alcohol, polyvinyl acetate (methanol solution) 2nd layer: Polymethyl methacrylate, polyvinyl chloride, polycarbonate, polystyrene, nitrocellulose (acetone solution) Combination III First layer: polystyrene-based elastomer (cyclohexanone solution) Second layer: polyvinyl alcohol, polyvinyl acetate (ethyl cellosolve solution). By sequentially stacking the above-mentioned 1 and 2 layers, it is possible to obtain a recording layer having good photosensitivity to laser light having a constant wavelength.

The dye may be selected in consideration of the compatibility with the polymer solution, and the first recording layer may be a dye having infrared and ultraviolet absorptivity, and the second recording layer may be a near infrared absorptive dye. By selecting a dye having, and by alternately stacking these layers, the infrared and ultraviolet absorbing materials sandwich the near infrared absorbing material, so that the pit shapes after sublimation of the recording layer are complementary to each other. The shape at the boundary between the pit and the non-pit portion is not significantly affected by the noise wavelength component of the laser light used as a whole, and can be prevented from becoming noise during reproduction.

Further, it is preferable that the dyes used in the first recording layer and the second recording layer are both colored by ultraviolet light and can be erased by visible light or near infrared light. The reason is that both the first and second recording materials are transparent in the unwritten state, and when these are colored by writing, they are highly safe to read and have a wide variety of visible light sources. This is because not only light to near-ultraviolet light is used, but also individual spectrum changes become large and a good S / N ratio can be obtained.

EFFECTS OF THE INVENTION As described above, according to the present invention, since the solubility in the conventional solvent is similar, the structure and the solubility which cannot be laminated because the dye is eluted during the next coating Photosensitive materials containing similar dyes can be laminated to form a thin film, the degree of freedom in selection of photosensitive materials will be further widened, and restrictions on combinations of photosensitive materials and solvents will be greatly reduced. You can

In addition, since dyes with appropriate absorption characteristics can be freely selected, the combination of appropriate dyes does not adversely affect the noise wavelength component in the laser light, and further provides a comprehensive absorption characteristic for a predetermined wavelength. The recording layer having the same can be obtained. In addition, since it is possible to configure the first and second photosensitive materials so that the light absorption spectra after coloring of the first and second photosensitive materials do not overlap each other, it is possible to easily multiplex the recording by the multi-layer structure, and the conventional optical information It is possible to obtain a high-density optical information recording medium having a recording capacity that is more than double the recording capacity of the recording medium.

Further, as a polymer containing a dye, various materials having ultraviolet resistance, infrared resistance, water resistance, solvent resistance, and weather resistance can be used in combination, so that it is possible to improve the overall performance by the complementary action of these materials. Become. That is, there is an effect that it is possible to obtain an optical information recording medium that is less deteriorated by an external light after the recording process.

[Brief description of drawings]

 The figure is a partial sectional view of the optical information recording medium of the present invention. Description of symbols of main parts 1 ... Substrate, 3 ... Second recording layer 2 ... First recording layer, 4 ... Third recording layer

Claims (1)

[Claims] 1. An optical information recording medium laminated on a transparent substrate and having a plurality of dye recording layers each containing a dye, wherein the adjacent dye layers are made of polymers insoluble in different solvents. An optical information recording medium comprising a dye dispersed in the polymer.