JPH06314440A - Optical information recording medium - Google Patents

Abstract

PURPOSE:To obtain a high reliability optical disk having enhanced moisture, heat and corrosion resistance by forming a protective coating film on a disk substrate with a formed information recording layer. CONSTITUTION:A disk substrate 1 with a formed information recording layer 2 is coated with a coating film 3 of poly-p-xylylene resin or a deriv. thereof. This disk substrate 1 is a single plate type one, an air sandwich type one obtd. by disposing a discoid substrate 1 with a formed information recording layer 2 on at least one substrate with a spacer in-between and bonding them or a contact stuck type one obtd. by directly sticking a discoid substrate 1 with a formed information recording layer 2 on at least one substrate.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical information recording medium (hereinafter referred to as an optical disc) used as a document file, an image file, a computer memory, etc., and particularly to a substrate of an optical disc and an information recording layer formed on the substrate. The present invention relates to a surface protective film provided on both or one of the above.

[0002]

2. Description of the Related Art In recent years, with the rapid increase in the amount of information to be handled, information processing technology has also been rapidly developed. Optical discs have been attracting attention as a means for processing and accumulating such a large amount of information. Is.

The structure of an optical disk used for such a purpose is a single plate type, an air sandwich type in which disk-shaped substrates having an information recording layer formed on at least one substrate are opposed to each other via a spacer, and bonded. It can be roughly classified into three types of a contact bonding type in which a disk-shaped substrate having an information recording layer formed on at least one substrate is directly bonded.

In either case, basically, the optical disk substrate is a disk-shaped transparent substrate formed of a material such as glass, a thermoplastic resin such as polycarbonate or acrylic resin, or a thermosetting resin such as epoxy resin, for recording information. A layer is provided, and any one of the above substrate materials is used depending on the purpose of use.

As the information recording layer provided on these transparent substrates, metal materials such as Al, Au, Ag and In, Te
C, TeTiAgSe, PbTeSe, TeO, TeO
₂ , TeOx, TbFe, TbCo, TbFeCo, G
dFe, GdCo, GdTbFe, GdTbCo, Gd
FeCo, SeInSb, TeO-Te (Ge, S
n) and the like, metal oxides, phthalocyanine dyes, organic dye materials such as naphthalocyanine dyes, and the like. These are provided on a transparent substrate by a method such as vapor deposition, sputtering, or coating, and these information recording layers Are used as read-only, write-once, and rewritable information recording media according to their characteristics.

Since these information recording layers are made of extremely thin films, they are easily scratched, and the scratches cause errors in reading and recording, and noise is mixed. In addition, depending on the material of the information recording layer, it may be oxidized or corroded by oxygen and moisture in the atmosphere, making it impossible to record and reproduce information.

Therefore, conventionally, the information recording layer is coated with an inorganic substance such as metal or ceramics, a solvent volatilization type nitrocellulose resin, an ultraviolet curable resin or the like to form a protective film for the information recording layer.

[0008]

By the way, these protective films are usually provided on the information recording layer. When a resin substrate is used as the substrate, there is also a problem of corrosion of the information recording layer due to moisture absorption and moisture permeation from the substrate side. When a glass substrate is used as the substrate, this problem can be solved, but on the other hand, the glass substrate lacks mass productivity, and problems such as damage and weight remain.

In order to improve moisture absorption and moisture permeability from the substrate, substrates such as thermosetting resin such as epoxy resin and olefin resin have been proposed, but the former lacks mass productivity as compared with thermoplastic resin. Also, the latter has a drawback in price.

However, the formation of a protective layer made of an inorganic material causes a large curing shrinkage during the formation of a coating film, and wrinkles and cracks in the information recording layer due to this stress and corrosion of the information recording layer due to the hygroscopicity of the protective film itself may occur. This is a cause of deterioration of recording characteristics and reproduction characteristics.

Further, a solvent volatilization type resin such as nitrocellulose requires a troublesome process for drying the solvent and has a problem in productivity, and there is a risk that the volatilized solvent deteriorates the working environment and causes a fire. In order to prevent this, a solvent recovery device is required, and there is a problem that the facility cost is high.

On the other hand, in recent years, attempts have been made to make up for the drawbacks of the protective film made of the above-mentioned materials by using an ultraviolet-curable resin having the characteristics of one-component, solvent-free and fast curing.

However, when the epoxy acrylate or urethane acrylate is used, the information recording layer is corroded by the impurity chlorine derived from the raw material, and when the epoxy resin or the like is used, the information recording layer is corroded by the acid generated from the photoinitiator. However, it is not always satisfactory.

In addition, the protective film formed by these methods can form a film on only one side of the disc in one step, and protects the information recording layer and both sides of the disc to prevent moisture absorption and moisture permeation from the substrate. Two or more steps are required to provide the layer. Further, in the case of an optical disc composed of two or more disc-shaped substrates, it is practically impossible to form a protective film covering the entire assembled product by these methods.

The present invention solves the above-mentioned problems and uses
Not only the information recording layer of an optical disk which is not affected by the structure and material, but also an optical disk having a protective film for covering the entire disk provided with the information recording layer or the entire assembled optical disk is provided. aqueous,
By covering the optical disk with a protective film having excellent gas barrier properties, chemical resistance, thermal stability, low temperature characteristics, etc., moisture resistance,
An object of the present invention is to provide a highly reliable optical disk having excellent heat resistance and corrosion resistance.

[0016]

In order to solve the above problems, a disk-shaped substrate 1 provided with an information recording layer 2 is coated with a film made of polyparaxylylene or its derivative (hereinafter referred to as polyparaxylylene resin or the like). It is coated with 3.

The optical information recording medium has a single plate structure composed of a disc-shaped substrate 1 provided with an information recording layer 2.
The information recording layer 2 is formed on at least one transparent substrate,
There is a case where this surface is bonded to another substrate 1 or a protective plate so as to face it, or a case where it is bonded via spacers 4 on the inner and outer circumferences.

There is also one in which the protective plate and the spacer 4 are covered with the film 3 made of polyparaxylylene resin or the like.

Further, an information recording layer 2 is formed on at least one transparent substrate 1 and is bonded with the surface thereof facing the other substrate 1, or spacers 4 on the inner and outer circumferences.
Some are joined via.

[0020]

Basically, by using the optical disk substrate 1 processed as shown in FIGS. 1 to 3, the spacer 4 and the protective plate as required, and assembling them, water repellency, gas barrier property and chemical resistance are obtained. , Moisture resistance, corrosion resistance, etc.

[0021]

EXAMPLE In the present invention, a disk-shaped substrate provided with an information recording layer is coated with a film made of polyparaxylylene resin or the like represented by the general formula in FIG. In the formula, X and Y are H or Cl, and n is a value greater than 5000.

The film made of polyparaxylylene resin or the like shown in FIG. 7 is formed by coating the optical disk substrate by the chemical vapor deposition method. Chemical vapor deposition is capable of coating at the molecular level, which was not possible with conventional liquid coating and powder coating.Also, coating at room temperature is possible regardless of the shape and material of the object to be coated. It is possible. In addition, a uniform coating having a uniform shape can be obtained. This chemical vapor deposition coating using a polyparaxylylene resin or the like has been developed and commercialized as a parylene resin by Union Carbide.

Such chemical vapor deposition is roughly classified into vaporization of the raw material diparaxylylene solid dimer (~ 17
Generation of stable diradical paraxylylene monomer by thermal decomposition of dimer at 5 ° C, ~ 1 Torr (~ 680)
Adsorption and polymerization of the radical paraxylylene on the substrate at the same time to form a thin film of high molecular weight polyparaxylylene (~ 35 ° C, ~ 0.1T).
The film is formed from the three steps of orr).

Specific examples of polyparaxylylene and the like include a) polyparaxylylene, b) polymonochloroparaxylylene, and c) polydichloroparaxylylene.

The appearance is colorless and transparent, and the melting points of these polymers are 280 ° C. for a) and 40 for b).
5 ° C, c) is 350 ° C. These coatings have excellent ability to prevent permeation of water vapor and various gases. Further, it is insoluble in organic solvents at 150 ° C. or lower, and has resistance to most acids and alkalis. Further, it is also excellent in that it has excellent electric insulation, heat resistance, and low temperature resistance and almost no outgas is generated.

These are coated on the substrate by the chemical vapor deposition method. This coating method can also be used to form a pinhole-free precision thin film, and it is possible to form a conformal coating that fits the shape of the substrate. Furthermore, it is possible to coat a wide variety of materials, narrow gaps with excellent permeability, and coating at room temperature, and there is the feature that coating distortion does not remain on the substrate.

The present invention imparts water resistance, moisture resistance, chemical resistance, cold heat resistance, corrosion resistance, etc. to an optical disk by using a polyparaxylylene resin or the like having various characteristics as described above and a coating method. An example of forming a film of polyparaxylylene resin or the like on an optical disc will be described with reference to the drawings.

1 and 2 respectively show a film 3 of polyparaxylylene resin or the like on an information recording layer 2 formed on a substrate 1 of an optical disk, and on a substrate 1 on which the information recording layer 2 of the optical disk is not formed. The case where the film 3 is formed is shown.

FIG. 3 shows a case where a coating 3 of polyparaxylylene resin or the like is formed on the entire optical disc substrate 1 provided with the information recording layer 2.

In the case of FIGS. 1 and 3, the optical disc can be used as it is for a single-disc optical disc such as a compact disc for music. FIG. 4 shows a double-sided contact type optical disc in which two substrates 1 of FIGS. 1 to 3 are used and are directly bonded by an adhesive layer 5 so that respective information recording layers 2 face each other.

In FIG. 5, one substrate 1 shown in FIGS. 1 to 3 is used, and the substrate 1 for the purpose of protecting the information recording layer 2 is adhesively bonded through the spacer 4 and the void layer 6 in the same manner. Layer 5
It is an air-sandwich type optical disc with a protective plate that can be used on one side.

In the process of FIG. 1, the information recording layer 2 is formed as a protective and moisture-proof film, and in the process of FIG. 2, the substrate 1 is formed as a protective and moisture-proof film. In any case, the film is not formed on the end surface (edge surface) of the substrate 1, but it goes without saying that the film may be formed on this surface as well. In addition, in the processing of FIG.
Both objectives in can be achieved.

Furthermore, in the case of an optical disk having an air sandwich structure or an optical disk joined to a protective plate, the inner and outer spacers 4 and the protective plate are coated with a film made of polyparaxylylene resin or the like. When used, the water repellency, gas barrier property, chemical resistance, moisture resistance, corrosion resistance and the like are further improved.

In the method according to the present invention, in the case of an optical disc composed of two or more substrates 1, the film 3 made of polyparaxylylene or the like after the optical disc is assembled.
It is also possible to coat the entire optical disk with this film 3 by forming the. However, in this case, the film 3 made of polyparaxylylene resin or the like is not formed on the information recording layer 2. FIG. 6 shows an example of a contact type optical disc using this method.

The film 3 of the polyparaxylylene resin or the like thus formed on the optical disk has a film thickness of about 0.2 μm to about 75 μm obtained by one-time processing. When the film 3 is formed on the information recording layer 2 formed on the substrate 1, the film thickness is about 0.5 μm.
It is preferably about m to about 50 μm.

Further, the surface of the disc-shaped substrate 1 provided with the information recording layer 2 on which the information recording layer 2 is not provided, and between the protective plate and the film 3 made of polyparaxylylene resin or the like, or polyparaxylylene. By providing a hard coat layer on the film 3 made of resin or the like, scratch resistance and hardness can be imparted.

As a material for forming such a hard coat layer, there are a heat curing type silicone hard coat and an ultraviolet curing type hard coat.
Considering the materials that do not like to be heated as described above, the ultraviolet curable hard coat is preferable. Furthermore, when an ultraviolet curable hard coat having an antistatic effect is used, it is possible to prevent dust and dirt from adhering in addition to providing scratch resistance and hardness.

Experimental Example 1 A read-only information recording layer 2 was provided on a polycarbonate disk substrate 1 having a diameter of 130 mm, and then a polymonochloroparaxylylene film 3 was formed to form a single plate as shown in FIG. I made an optical disc. The hardness of the coating 3 was H to 2H in terms of pencil hardness. The optical disc was left in an atmosphere of 80 ° C. and a relative humidity of 85%, and a humidity resistance test was conducted.
No change in appearance was observed even after 2000 hours, and the information recording layer 2 was not affected.

Comparative Example 1 70 parts of trimethylolpropane triacrylate, 30 parts of neopentyl glycol diacrylate and 5 parts of 1-hydroxycyclohexyl phenyl ketone were charged in a container equipped with a stirrer, mixed and mixed, and an ultraviolet curable resin composition was prepared. I created a thing. This composition was applied on the surface of the polycarbonate disk substrate 1 provided with the information recording layer 2 used in Experimental Example 1 having the information recording layer 2 by a spin coating method, and then irradiated with ultraviolet rays of 2000 mJ / cm ^2. Let it harden,
A single-plate optical disc as shown in FIG. 1 was produced. The hardness of the coating film was H to 2H in terms of pencil hardness. A humidity resistance test was performed on this optical disk under the same conditions as in the experimental example, but after 250 hours, many pinholes were generated in the information recording layer 2.

Experimental Example 2 After the rewritable information recording layer 2 was provided on the polycarbonate disk used in Experimental Example 1, a polymonochloroparaxylylene film 3 was formed to form an optical disk substrate as shown in FIG. Created 1. After that, the two liquid crystal acrylic substrates 3 are bonded so that the two information recording layers 2 of the optical disk substrate 1 face each other.
No. 26 (manufactured by ThreeBond Co., Ltd.) is used for bonding and FIG.
The contact type optical disk which can be used on both sides as shown in Fig. 2 was created. In this optical disc, two optical discs shown in FIG. 3 are opposed to each other, and the opposing surfaces are closely adhered by an adhesive layer 5.
When a humidity resistance test was conducted on this optical disk under the same conditions as in Experimental Example 1, no change in appearance was observed even after 2000 hours, and the information recording layer 2 was not affected and could be used.

Comparative Example 2 On the surface of the polycarbonate disk substrate 1 provided with the rewritable information recording layer 2 used in Experimental Example 2 on which the information recording layer 2 was provided, the ultraviolet curable resin composition prepared in Comparative Example 1 was applied. 2000mJ / cm after applying by spin coating method
^It was irradiated with ultraviolet rays ² and cured to prepare a single-plate optical disk as shown in FIG. Then, in the same manner as in Experimental Example 2, two optical disk substrates 1 were set so that the information recording layers 2 face each other.
1 and 3926 were used to bond them to each other to prepare a contact-type optical disk that can be used on both sides. A moisture resistance test was conducted on this optical disk under the same conditions as in Experimental Example 1, but after 200 hours, many pinholes were generated in the information recording layer 2. Also, some water droplets, which are considered to have been generated by moisture permeation, were found inside the disk substrate 1.

Experimental Example 3 On the surface of the polycarbonate disk substrate 1 provided with the rewritable information recording layer 2 used in Experimental Example 2 on which the information recording layer 2 was provided, the ultraviolet curable resin composition prepared in Comparative Example 1 was applied. 2000mJ / cm after applying by spin coating method
^It was irradiated with ultraviolet rays ² and cured to prepare a single-plate optical disk as shown in FIG. Next, the two optical disk substrates 1 are bonded together using an olefin-based hot melt adhesive (adhesive layer 5) so that the information recording layers 2 face each other, and a double-sided contact-type optical disk is produced. did. Further, a coating film 3 of polymonochloroparaxylylene was formed on the surface of this optical disk to prepare an optical disk as shown in FIG. When this optical disk was subjected to a humidity resistance test under the same conditions as in Experimental Example 1, no change in appearance such as pinholes or water droplets was observed even after 1500 hours, and the information recording layer 2 was not affected and could be used. It was

[0043]

As described above, the optical disk according to the present invention has the information recording layer protective film excellent in moisture resistance, heat resistance, gas barrier property, corrosion resistance, etc., and has long-term reliability. Moreover,
The obtained film has the same hardness as that of an ultraviolet curable coating agent, and also has an effect of preventing the information recording layer from being deformed by scratches or foreign matters in the adhesive.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a state in which a film of polyparaxylylene resin or the like is formed on an information recording layer formed on a substrate of an optical disc.

FIG. 2 is a cross-sectional view of a state in which a film of polyparaxylylene resin or the like is formed on the surface of the substrate of the optical disc where the information recording layer is not formed.

FIG. 3 is a cross-sectional view showing a state in which a film of polyparaxylylene resin or the like is formed on a surface of an optical disc on which an information recording layer is formed and a surface where the information recording layer is not formed.

4 is a cross-sectional view of a contact type optical disc in which two optical discs of FIG. 3 are directly adhered to each other and can be used on both sides.

FIG. 5 is a cross-sectional view of an air sandwich type optical disc that can be used on one side.

FIG. 6 is a cross-sectional view of a contact type optical disc that can be used on both sides, in which a film of polyparaxylylene resin or the like is formed on the entire outer surface.

FIG. 7 is a general chemical formula of a polyparaxylylene resin.

[Explanation of symbols]

 1 substrate 2 information recording layer 3 film

Claims (7)

[Claims] 1. An optical information recording medium, characterized in that a disk substrate provided with an information recording layer is coated with a film made of polyparaxylylene resin or a derivative thereof. 2. The optical information recording medium has a single plate structure including a disc-shaped substrate provided with an information recording layer.
Optical recording medium. 3. The optical information recording medium is at least one.
2. The optical information recording medium according to claim 1, wherein an information recording layer is formed on one transparent substrate, and this surface is joined so as to face the other substrate or the protective plate. 4. The optical information recording medium is at least one.
2. The optical information according to claim 1, wherein an information recording layer is formed on one transparent substrate, this surface is opposed to another substrate or a protective plate, and they are bonded via spacers on the inner and outer circumferences. recoding media. 5. The optical information recording medium according to claim 1, wherein the protective plate and the spacer are coated with a film made of polyparaxylylene resin or a derivative thereof. 6. The optical information recording medium according to claim 1, wherein an information recording layer is formed on at least one transparent substrate and is bonded so that this surface faces another substrate. 7. The optical information recording according to claim 1, wherein an information recording layer is formed on at least one transparent substrate, and this surface is opposed to another substrate and is bonded via spacers on the inner and outer circumferences. Medium.