JPS61172230A - Optical information recording medium - Google Patents

Abstract

PURPOSE:To prevent mechanical damage and deterioration due to the O2, moisture, etc., in air by providing a resinous sheet or a resinous coat on the surface of an optical information recording layer on a transparent resinous substrate, and furnishing successively a transparent inorg. thin film and a vapor-shape polymerization polyparaxylylene (derivative) film on the surface. CONSTITUTION:An optical information recording layer 2 of a combination of metals or metallic oxides such as Te, TeO2, Ge, Se and Al is formed on a transparent resinous substrate 1 of polymethyl methacrylate, polycarbonate, etc. A transparent resinous sheet 1' similar to the substrate 1 is adhered onto the layer 2 with an adhesive 3, and then a transparent inorg. thin film 4 of Si3N4, SiO2, etc. is formed on the substrate 1 and the resinous sheet 1' by vapor deposition, etc. Then a protective film 5 of polyparaxylylene, polymonochloroparaxylylene, polydichloropolyparaxylylene, etc. is formed on the film 4. Since the film 5 efficiently blocks the intrusion of O2 and steam, the deterioration of the recording layer 2, the generation of cracks in the inorg. film 4 and the stripping off of the film are prevented. An optical information recording medium having excellent resistance to environment and capable of being preserved for a long period is thus obtained.

Description

[Detailed Description of the Invention] Industrial Application Field 2 - One aspect of the present invention is an optical disc, a video disc, or a DA
The present invention relates to an optical information recording medium that can be used as a D compact disc.

2. Description of the Related Art In recent years, optical disk memories have been widely used in which an optical information recording thin film is formed on a transparent substrate and recording and reproduction can be performed using laser light. However, the information recording layer alone cannot be stored for long periods of time due to mechanical damage and deterioration due to oxygen, moisture, etc. in the air. Therefore, the surface is protected by covering it with an organic or inorganic material.

Problems to be Solved by the Invention Although photocurable resins and the like are being considered as organic materials,
The moisture permeability cannot be made sufficiently small, making it difficult to suppress deterioration due to moisture. Therefore, inorganic materials with extremely low moisture permeability, such as silicon oxide and silicon nitride, are being considered to be formed by vapor deposition, sputtering, or CVD methods, but they tend to crack or peel off from the substrate due to thermal shock. It is not possible to obtain a sufficient moisture-proofing effect. 3-7 Japanese Patent Application Laid-Open No. 57-130241 describes that a resin dissolved in an organic solvent is applied to the surface of an inorganic moisture-proof film to form a film to suppress cracks and the like. However, with this configuration, the thickness of the organic film at the edge of the disk substrate becomes uneven, and peeling tends to occur at the boundary between the inorganic film and the organic film due to the difference in thermal expansion coefficient between the inorganic material and the inorganic material in a hot and humid environment. , diffuse reflection of light and agglomeration of moisture occur at the boundary.
Furthermore, cracks occur in the inorganic film, making it difficult to obtain a sufficient moisture-proofing effect.

Means for Solving the Problems In order to solve the above problems, the present invention provides a structure in which a resin plate is adhered to the surface of the optical information recording layer on the transparent substrate or another resin coating layer is provided. A transparent inorganic thin film is formed on the outer surface of a resin plate or a resin coating layer, and the surface is further coated with polyparaxylylene or a derivative thereof formed by a gas phase polymerization method.

The polyparaxylylene or its derivative film formed by the gas phase polymerization method has a uniform thickness regardless of the shape of the substrate, and is an organic material with a low moisture permeability equal to or lower than that of polyvinylidene chloride. Therefore, it is possible to suppress cranking and peeling of the transparent inorganic thin film with low moisture permeability, and to obtain an optical information recording medium having a protective film with an extremely high moisture-proofing effect.

Embodiment FIGS. 1 and 2 show an example of the structure of an optical information recording medium according to the present invention. 1 is a transparent resin substrate, and 2 is a recording layer. In FIG. 1, a transparent resin plate 1' similar to the substrate 1 is bonded to the recording layer 2 with a resin adhesive 3, and in FIG. 2, a resin coating layer 6 is provided on the recording layer 2. 4 is an inorganic thin film, and 6 is a polyparaxylylene film.

As the recording layer 2, Te, TaO2, Ge, Sn, S
It is made of a thin film made of a combination of metals such as E, An, etc., and metal oxides, and these compositions react with moisture, oxygen, etc., causing deterioration. The substrate is generally polymethyl methacrylate,
Polycarbonate, epoxy resin, etc. are used as the resin transparent substrate. As the resin forming the adhesive 3 and the resin coating layer 6, an acrylate-based resin 6--ultraviolet curing resin is mainly used. As an inorganic thin film,
SiO, 5i02, etc. by vapor deposition, sputtering method, CvD,
Metal alcohols such as 5i3N4 by plasma CvD method
Examples include composite glass of S x 02 and ZrO2, which is produced by a coating method that undergoes hydrolysis and polymerization.

Next, the types of monomers and synthesis methods for polyparaxylylene and its derivatives using the gas phase polymerization method are shown below. The general physical properties of are shown in the table below.

1 unit of rice! -cm/cm, Watari, cmHy[:
60℃90%RH.

According to the cup method (J Is, Z, 0208)] 1st
As shown in the figure, an optical information recording layer 2 mainly composed of Te and TeO2 is provided on one side of a polycarbonate substrate 1 with a thickness of 1.2 cm by vacuum evaporation, and an epoxy acrylate ultraviolet curing resin is used as an adhesive to bond the above substrate. The entire optical disk consists of resin plates made of the same material. A film of silicon nitride with a thickness of 150° was entirely formed on the surface by the plasma CVD method, and the surface was further coated with a polyparachloroxylylene film with a thickness of 5 μm by the synthesis method described above.

Optical disc A of this example; Optical disc B as a comparative example with a laminated structure and no protective film at all; Optical disc C1 with only an inorganic thin film as a protective film; Furthermore, a polyvinylidene chloride film was formed on the inorganic protective film by a coating method. An accelerated deterioration test was conducted on the optical disk D in an atmosphere of 70° C. and 96% RH, and the relationship between the rate of change in light (wavelength 830 nm) transmittance of the recording layer and time was investigated. The results are shown in Figure 3. As is clear from the figure, the transmittance of Example A tends to change even after 100 days, whereas that of Comparative Example B.

In both C and D, the transmittance changed due to deterioration.

Further, no deterioration of the product of this example was observed even in an accelerated test under a temperature cycle of 70° C. and 30° C. at 90% RH.

These two experiments show that it has excellent long-term storage stability.

In addition, similarly good results were obtained with the structure shown in FIG.

9. In addition, as other inorganic thin films, silicon oxide by vapor deposition method,
The same applies to the combination of a glass material obtained by coating a mixture of zirconia alkoxylate, tf [alkoxylate (as an alkoxylate, isopropylate, ethylate) and then hydrolyzing and polycondensing it, and polyparaxylylene or polyparadichloroxylylene. Good results were obtained.

Effects of the Invention As described above, according to the present invention, by providing a protective film in which an inorganic thin film and a polyparaxylylene or its derivative film are laminated, it has excellent environmental resistance such as moisture resistance and can be stored for a long period of time. It is possible to obtain an optical information recording medium which is extremely advantageous in practice.

[Brief explanation of drawings]

1 and 2 are sectional views of essential parts of an optical information recording medium according to an embodiment of the present invention, and FIG. 3 is a graph showing the temporal characteristics of the rate of change in light transmittance in an accelerated deterioration test. 1...Substrate, 2...Recording layer, 4. Old...
- Inorganic thin film, 10...-1 6... Polyparaxylylene or its derivative film.

Claims (3)

[Claims] (1) A resin plate is adhered or a resin coating layer is provided on the surface of the optical information recording layer on a transparent resin substrate, a transparent inorganic thin film is formed on the outer surface of the substrate and the resin plate or the resin coating layer, and the surface is further covered with air. An optical information recording medium characterized by being coated with a film of phase polymerized polyparaxylylene or a derivative thereof. (2) The optical information recording medium according to claim 1, wherein the transparent inorganic thin film comprises at least one selected from the group consisting of silicon nitride, silicon oxide, and composite glass of zirconia and silicon oxide. (3) The optical information recording medium according to claim 1, wherein the polyparaxylylene derivative is at least one of polymonochloroparaxylylene and polydichloropolyparaxylylene.