JPH0384751A - Optical information recording medium coated with silicon dioxide and production thereof - Google Patents

Abstract

PURPOSE:To remarkably improve the moisture resistance, corrosion resistance and scratching resistance of the optical information recording medium and to reduce the water absorptivity thereof by treating the entire surface of the recording medium or the surface of the transparent substrate thereof with an acidic soln., then forming a silicon oxide film over the entire surface of the optical information recording medium. CONSTITUTION:The entire surface of the optical information recording medium constituted by providing a recording layer and a dielectric layer and/or protective layer on the transparent substrate made of a synthetic resin or the surface of the transparent substrate is treated with the acidic soln. and thereafter, the silicon oxide film is formed over the entire surface of the optical information recording medium. Consequently, the above-mentioned surface bonds securely to the silicon oxide film and, therefore, the optical information recording medium coated with the silicon dioxide having the excellent adhesive property is obtd. Since the silicon oxide film having the excellent adhesive property is formed over the entire surface of the optical information recording medium in such a manner, the moisture resistance, corrosion resistance and scratching resistance are improved and the deformation by the water absorption is extremely decreased.

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to an optical information recording medium whose entire surface is coated with a silicon oxide film, and more particularly to a silicon oxide coated optical information recording medium with improved moisture resistance, corrosion resistance, and scratch resistance, and its production. Regarding the method. [Prior Art] In recent years, many types of optical information recording media such as optical discs and video discs have been developed and are commercially available. These optical information recording media have a basic structure that focuses laser light onto a rotating disk and detects the strength of the reflected light from the disk. A typical example is one in which a recording layer is provided on a substrate. By the way, as recording medium materials used for the recording layer,
Metals or metal alloys such as Te, Ti, low Te oxides,
Organic dye thin films, silver salt thin films, photochromic compounds, etc. have been widely proposed and used, but all of these materials are easily oxidized and hydrolyzed, so it is necessary to add a protective layer to prevent the recording layer from deteriorating. Development is underway. In addition, in optical information recording media that use synthetic resin substrates, warping occurs due to water absorption and swelling of the substrate, which may cause the recording layer to peel off, signal reading to become impossible, or the amount of water that permeates. This causes problems such as deterioration of the recording layer. Therefore, how to solve these problems and ensure the reliability of optical information media has become an important issue. Conventionally, it has been proposed to provide various synthetic resin layers or transparent dielectric layers such as silicon dioxide on the surface of the recording layer as a protective layer. For example, in JP-A No. 61-39949, 1 to 2 molecular layers of a silane coupling agent or a titanium coupling agent are provided on the surface of an optical information recording layer provided on one side of a transparent substrate. Alternatively, it has been proposed to improve moisture resistance and corrosion resistance by forming polyvinylidene chloride copolymer-containing layers on both surfaces of the recording layer and the substrate. However, when only the surface of the recording layer is protected with a polyvinylidene chloride copolymer-containing layer, it is not possible to block moisture permeating from the substrate surface side. It is not possible to prevent deterioration of the recording layer due to peeling or permeated moisture, and this problem also occurs when the surface of the recording layer is covered with a dielectric layer. Further, even in optical information recording media having a structure in which a reflective layer is provided on the surface of the recording layer or a reflective layer is provided via a dielectric layer, the problem of water absorption from the substrate side cannot be solved. On the other hand, if a polyvinylidene chloride copolymer-containing layer is formed on both surfaces of the recording layer and the substrate, a resin layer with poor scratch resistance will be formed on the surface of the substrate, which serves as a path for light.
There is a risk that the basic performance of an optical information recording medium will be significantly impaired, such as signal deterioration or sensitivity deterioration. Moreover, even if polyvinylidene chloride copolymer-containing layers are formed on both surfaces, the moisture resistance is not sufficient and deterioration of the recording layer due to permeated moisture cannot be completely prevented. Furthermore, some optical information recording media have a structure such as an adhesive lamination structure or an air sandwich structure, and since these have a double-sided lamination structure with the recording layer as the central layer, the problem of warping can be alleviated. Deterioration of the recording layer due to permeated moisture cannot be prevented. In addition, SiO or Sing is added to the upper surface or upper and lower surfaces of the recording layer.
, MgFz , AβN, etc. can protect the recording layer from oxidation and hydrolysis; however, these transparent dielectric materials have poor adhesion to the synthetic resin that serves as the substrate. It is difficult to use it for substrate maintenance. Incidentally, in recent years, in order to modify the surface of a synthetic resin molded article, a technique of coating it with a thin film of an oxide such as silicon dioxide has been developed and put into practical use. Conventionally, various methods such as vacuum evaporation, sputtering, ion blating, and plasma CVD have been known as methods for coating oxide films, etc., but these film forming methods require special equipment, There is a problem in that it is difficult to form a coating on the surface of a large molded article or a molded article with a complicated shape, and furthermore, the adhesion between the synthetic resin molded article and the coating is insufficient. Recently, instead of directly coating the surface of a synthetic resin molded body with a silicon dioxide film, a silicon-containing film with good adhesion is coated on the surface of the synthetic resin molded body in advance as a primary film (brimer), and then a silicon-containing film with good adhesion is applied on top of that. A method of creating a silicon dioxide film with good adhesion to the primary film has been proposed (Japanese Unexamined Patent Publication No. 6
1-12734). According to this method, since the brimer is cured to form a polymer having siloxane bonds, the adhesion between the silicon dioxide film and the brimer is improved, and a more durable coating can be obtained than in the conventional method. Moreover, since a coating and dipping method can be used, it is also applicable to large-sized or complicated-shaped synthetic resin molded bodies. However, in this method, almost no strong chemical bond is formed between the brimer and the synthetic resin molded body, so the adhesion between the synthetic resin molded body and the brimer is insufficient, and therefore the synthetic resin of the silicon dioxide film Adhesion to molded bodies is also not sufficient. Therefore, even if a conventionally known silicon oxide coating method is simply applied to the formation of a protective layer of an optical information recording medium, it is difficult to form a coating with excellent adhesion to a substrate. [Problems to be Solved by the Invention] The purpose of the present invention is to improve moisture resistance, corrosion resistance, and scratch resistance.
Another object of the present invention is to provide an optical information recording medium that undergoes extremely little change in shape due to water absorption. Another object of the present invention is to provide a coated optical information recording medium having a silicon oxide coating on the entire surface with excellent adhesion to a substrate. As a result of intensive research to overcome the problems of the prior art, the present inventors have discovered an optical information recording medium in which a recording layer, a dielectric layer and/or a protective layer are provided on a transparent substrate made of synthetic resin. By forming a silicon oxide film on the entire surface of the optical information recording medium after treating the entire surface or the surface of the transparent substrate with an acidic solution (blimmer treatment), it is possible to form a silicon oxide film with excellent adhesion to the substrate. ,
It has been found that because the entire surface is coated with a silicon oxide film, an optical information recording medium can be obtained that has significantly improved moisture resistance, corrosion resistance, and scratch resistance, and has extremely low water absorption. The present invention has been completed based on these findings. [Means for Solving the Problems] According to the present invention, in an optical information recording medium in which a recording layer, a dielectric layer and/or a protective layer are provided on a transparent substrate made of synthetic resin, the entire surface or the transparent substrate can be Provided are a silicon oxide-coated optical information recording medium and a method for manufacturing the same, characterized in that a silicon oxide film is formed on the entire surface of the optical information recording medium after the surface is treated with an acidic solution. Each component of the present invention will be explained below. (Optical Information Recording Medium) The optical information recording medium used in the present invention has a multilayer structure in which a recording layer, a dielectric layer, and/or a protective layer are provided on a transparent substrate made of synthetic resin. The synthetic resin used as the material for the substrate is not particularly limited as long as it is a synthetic resin with excellent transparency that is generally used for optical information recording media, such as polycarbonate resin, acrylic resin, and epoxy resin. As the recording layer, TbFeCo, GdFe, TbCo,
DyFe, NdDyFeCo, TbFe, GdFeB1
Any conventionally known recording film such as a recording film made of , GdTbFe, etc., or a film made of a phase change recording material or a dye-based recording material can be used. As the material for the dielectric layer and/or the protective film, Sto
Dielectric materials that form an SL-based transparent layer, such as SiNx, SiAβON, and SiAβN, can be preferably used. The laminated structure of the optical information recording medium used in the present invention is as follows:
Typical examples include dielectric layer/recording layer/protective layer or substrate/recording layer/protective layer. In addition to single-layer optical information recording media, two optical information recording media, each having a recording layer, a dielectric layer, and/or a protective layer on a transparent substrate made of synthetic resin, are placed on the recording layer side via an adhesive layer. Even if the structure is such that the surfaces of the substrate are bonded together, for example, substrate/dielectric layer/recording H/protective layer//viewing layer//protective layer/recording M/dielectric layer/substrate. good. Such a laminated structure has fewer problems with warping. (Acidic solution) The acidic solution used in the present invention includes, for example, monochloroacetic acid, dichloroacetic acid, acetic acid, formic acid, propionic acid, acetoacetic acid, trichloroacetic acid, trifluoroacetic acid, hydrochloric acid, sulfuric acid,
It is a solution in which an acid such as phosphoric acid, sulfuric acid, chromic acid, or chromic acid is dissolved in an alcohol such as methanol or ethanol, or a solvent such as water. The concentration of acid in the acidic solution is not particularly limited, but from the viewpoint of surface treatment efficiency etc., it is usually 0.1 to 5% by weight.
is preferred. Brimer treatment using an acidic solution is performed by applying the acidic solution to the entire surface of the optical information recording medium or the surface of the transparent substrate using a dipping method, spin-coding method, spraying method, etc., and drying it. In this case, after coating, it is preferable to air dry at room temperature for about 1 to 2 hours, or to dry for several minutes in a high temperature atmosphere, for example, for about 1 to 5 minutes in a hot air dryer at about 90°C. In addition, in the case of an aqueous solution, the treatment temperature is usually 6 by the immersion method.
After processing at about 0 to 80° C. for several minutes to more than ten minutes, it is preferable to air dry or heat dry. Thus, the surface of the transparent substrate made of synthetic resin is oxidized and modified by being treated with the acidic solution, and its adhesion to the silicon oxide film is improved. (Formation of silicon oxide film) In the present invention, a silicon oxide film is formed on the entire surface of the optical information recording medium treated with the acidic solution. Examples of silicon oxide include SiOw and SiO.
O, (2kx≧1), St/Ml! Any known S1-based oxide such as ON can be used. As a method for forming the film, normal film thinning techniques such as vapor deposition, sputtering, CVD, and liquid phase growth can be employed. As the silicon oxide film, a silicon dioxide film is preferable.As a method for forming the silicon dioxide film, a CVD method using silane gas, a sputtering method using a quartz plate as a target, a dipping method using an organic solvent of an organosilicon compound, or There is a precipitation method in which silicon dioxide is immersed in a supersaturated hydrofluorosilicic acid solution to deposit a silicon dioxide film. Among these, the precipitation method is easy to work with and can form a uniform film, so
Particularly preferred. As for this precipitation method, a known method disclosed in detail in JP-A-61-12734 can be applied. A supersaturated hydrofluorosilicic acid solution of silicon dioxide is made by dissolving silicon dioxide (silica gel, aerosil, silica glass, other silicon dioxide-containing materials, etc.) in a hydrosilicic acid solution, and then using water or a reagent (boric acid, Aluminum chloride, etc.) is added to create a supersaturated state of silicon dioxide. An optical information recording medium treated with an acidic solution may be brought into contact with this treatment liquid. The contact may be carried out by immersing the optical information recording medium in the processing liquid or by allowing the processing liquid to flow down onto its surface, but the immersion method is preferable in order to form a uniform coating. The concentration of hydrofluorosilicic acid in the treatment solution is preferably 1 to 2 moles/flood, and in particular, after saturating the aqueous solution of hydrofluorosilicic acid with a concentration higher than 2 moles/β with silicon dioxide, diluted with water to
A concentration of 2 to 2 molar is desirable because the film formation rate is fast and coating can be carried out efficiently. In order to efficiently obtain a homogeneous film, it is preferable to continuously add and mix the boric acid aqueous solution while the optical information recording medium is immersed in the treatment liquid, and to circulate the treatment liquid and filter it with a filter. The amount of boric acid added to achieve a supersaturated state is usually I
~40 X I O-” moles, preferably 1,2X
10-" to 10X I O-" is desirable for forming a uniform coating quickly. When silica gel is used as a source of silicon dioxide, a filter with a pore size of 1.5 μm or less is preferable, and when silica glass or the like is used, a filter with a pore size of 10 μm or less is preferable. In addition, when putting the processing liquid into an immersion tank and bringing it into contact with the optical information recording medium, it is important to ensure that the processing liquid flows in a laminar flow over the surface of the optical information recording medium during immersion. Preferable for forming a homogeneous film. The thickness of the silicon oxide film can be determined as appropriate depending on the purpose of use, but usually, the purpose of surface modification can be achieved with about several hundred to several thousand people. [Function] In the conventional brimer treatment using a silicon compound such as a silane coupling agent, no strong chemical bond is formed between the brimer and the surface of the synthetic resin substrate. On the other hand, when treated with an acidic solution, the surface of the synthetic resin transparent substrate is oxidized, the bonds in the main chain of the polymer are broken, hydrogen abstraction reactions, etc. occur, and hydroxyl groups (-OH) and carboxyl groups are formed on the surface. It is presumed that functional groups such as (-COOH) and amino groups (-NH) are generated. These functional groups form 5L (
OH)4 participates in the polycondensation reaction during the process of polycondensation,
It is presumed that chemical bonding occurs with the silicon oxide film produced. As described above, according to the brimer treatment in the present invention,
The synthetic resin substrate is modified and, as a result, is strongly bonded to the silicon oxide film, so a silicon oxide coated optical information recording medium with excellent adhesion can be obtained. Furthermore, the adhesion between the silicon oxide coating and the protective layer made of a Si-based dielectric material provided on the recording layer of the optical information recording medium is also good. Since the optical information recording medium of the present invention has a structure in which its entire surface is coated with a silicon oxide film with excellent adhesion, moisture resistance, corrosion resistance, and scratch resistance are improved, and the shape change due to water absorption is extremely small. It also has excellent heat resistance. Furthermore, it can be stored for a long time under a wide range of temperature and humidity conditions. [Example] The present invention will be specifically explained below with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples. The method is as follows. Accelerated Deterioration Test> After holding a silicon oxide coated optical information recording medium (disk) for 3 weeks in a constant temperature machine at 65°C and 95% RH, C/N, maximum burst length of medium defects, mechanical Characteristics were evaluated. On stop Z: Measured at rotation speed 1.800 rpm, frequency 3.7 MHz,
The writing laser power was approximately 5 mW, as a result of minimizing the secondary high frequency. The measurement position was the innermost circumference of the disk, and the results were the average value of 100 track measurements. A signal was written using the burst byte (2.7) RLL modulation method, and comparisons were made before and after the accelerated deterioration test. The measurement position was the innermost circumference of the disk, and the results were for 100) racks. The radial inclination of the disk was measured after being kept in an atmosphere of 65° C. and 95% RH for 3 weeks. The measurement position was 45 mm in the radial direction from the center of the disk. Note that only the single-plate specification disc was evaluated. [Example 1] Optical disk substrate made of polycarbonate resin (diameter 1
30 mm, thickness 1.2 mm), on top of which a dielectric layer (S 1
AAON)/Record 1! An optical information recording medium having a structure in which (TbFeC.)/protective layer (SiAβON) was provided in this order was created. This optical information recording medium was immersed in an isopropyl solution of monochloroacetic acid (concentration 1% by weight), and then placed in a hot air dryer for 90 minutes.
It was dried by heating at 0° C. for 3 minutes. The processed thickness was approximately 100 pieces. The entire surface of the optical information recording medium that has been subjected to the above treatment is
A silicon dioxide film was deposited using a silicon dioxide film manufacturing apparatus similar to that shown in Japanese Patent No. 1-12734. That is, the silicon dioxide film manufacturing apparatus has a dipping tank consisting of an outer tank and an inner tank, and the space between the inner tank and the outer tank is filled with water. This water is heated with a heater to a temperature of 35°C, and is stirred with a stirrer to make the temperature distribution uniform. The inner tank consists of a front part, a middle part, and a rear part, and each part is filled with an aqueous solution of hydrofluorosilicic acid at a concentration of 2.0 mol/β in which silicon dioxide is dissolved and saturated using industrial silica gel powder as a source of silicon dioxide. It is filled with a reaction solution of 3I2 diluted to 20% using 3I2. At this point, the circulation bomb was activated to discharge a certain amount of the reaction liquid from the rear of the inner tank, filter it with a filter, and start circulating the treated liquid back to the front of the inner tank. Thereafter, a 0.5 mol/I2 boric acid aqueous solution was continuously poured into the rear part of the inner tank and maintained for 10 hours. In this state, the reaction solution became a treatment solution having an appropriate degree of silicon dioxide supersaturation. Here, the absolute removal rate of the filter was adjusted to 1.5 .mu.m, and the treatment liquid circulation rate was adjusted to 240 mI2/min (since the total amount of treatment liquid was about 34, the circulation rate was 8%/min). Then, the optical information recording medium subjected to the above treatment was immersed vertically in the middle of the inner tank, and under the conditions described above (0.5 mol/β boric acid aqueous solution was added for 0.2 m 127 minutes, and the circulation was carried out at 8%/min). (filtered with a 1.5 μm filter) and held for 16 hours. As a result, an optical information recording medium was obtained whose entire surface was covered with a silicon dioxide film having a thickness of about 3000 nm. [Example 2] A silicon dioxide film-coated optical information recording medium was obtained in the same manner as in Example 1, except that acetoacetic acid was used as the acid, and evaluated in the same manner.

[Example 3] Silicon dioxide was prepared in the same manner as in Example 1, except that an isobutanol solution of monochloroacetic acid (0.5% by weight) and phosphoric acid (0.1% by weight) was used as the acidic solution in the brimer treatment. A film-coated optical information recording medium was obtained and evaluated in the same manner. [Comparative Example 1] An optical information recording medium coated with a silicon dioxide film was obtained in the same manner as in Example 1, except that the brimer treatment with an acidic solution was not performed, and the same evaluation was performed. Table 1 summarizes the results of accelerated deterioration tests of the silicon dioxide film-coated optical information recording media obtained in Examples 1 to 3 and Comparative Example 1. [Example 4] Two single-plate optical disks produced in Example 1 were bonded together on their recording layer sides using an acrylic adhesive to create an optical information recording medium with a bonded structure. Except for using this optical information recording medium with a laminated structure,
An optical information recording medium coated with a silicon dioxide film was obtained by performing the brimer treatment in the same manner as in Example 1, and was evaluated in the same manner. [Example 5] Example 4 except that the brimer treatment was the same as in Example 2.
An optical information recording medium coated with a silicon dioxide film was obtained in the same manner as above, and evaluated in the same manner. [Example 6] Example 4 except that the brimer treatment was the same as in Example 3.
An optical information recording medium coated with a silicon dioxide film was obtained in the same manner as above, and evaluated in the same manner. [Comparative Example 2] A silicon dioxide film-coated optical information recording medium was obtained in the same manner as in Example 4, except that the brimer treatment was not performed, and evaluated in the same manner. Table 2 summarizes the results of accelerated deterioration tests of the silicon dioxide film-coated optical information recording media obtained in Examples 4 to 6 and Comparative Example 2. (Margin below)

【Effect of the invention】

According to the present invention, it is possible to form a silicon oxide film with excellent adhesion over the entire surface of an optical information recording medium, thereby improving moisture resistance and corrosion resistance, and producing an optical information recording medium whose shape changes extremely little due to water absorption. can be provided. Therefore, long-term storage is possible under a wide range of temperature and humidity conditions. Furthermore, in a single-plate optical information recording medium, improved moisture resistance prevents deterioration of mechanical properties such as warping due to water absorption. Furthermore, since a silicon oxide film with high transparency and surface hardness is formed over the entire surface, it has excellent scratch resistance and does not cause signal deterioration or sensitivity deterioration.

Claims (5)

[Claims] (1) In an optical information recording medium in which a recording layer, a dielectric layer, and/or a protective layer are provided on a transparent substrate made of synthetic resin, the entire surface or the surface of the transparent substrate is treated with an acidic solution, and then the optical information recording medium is A silicon oxide coated optical information recording medium characterized by forming a silicon oxide film over the entire surface. (2) An optical information recording medium is formed by attaching two optical information recording media each having a recording layer, a dielectric layer and/or a protective layer on a transparent substrate made of synthetic resin to the surface of the recording layer side via an adhesive layer. 2. The silicon oxide coated optical information recording medium according to claim 1, which has a structure in which two layers are bonded together. (3) In an optical information recording medium in which a recording layer, a dielectric layer and/or a protective layer are provided on a transparent substrate made of synthetic resin, the entire surface or the surface of the transparent substrate is treated with an acid solution, and then the optical information recording medium is A method for producing a silicon oxide-coated optical information recording medium, which comprises forming a silicon oxide film over the entire surface. (4) An optical information recording medium is formed by attaching two optical information recording media each having a recording layer, a dielectric layer and/or a protective layer on a transparent substrate made of synthetic resin to the surface of the recording layer side via an adhesive layer. 4. The method of manufacturing a silicon oxide-coated optical information recording medium according to claim 3, wherein the optical information recording medium is of a structure in which two layers are bonded together. (5) The silicon oxide film is a silicon dioxide film, and after the entire surface of the optical information recording medium or the surface of the transparent substrate is treated with an acidic solution, the optical information recording medium is treated with a supersaturated hydrofluorosilicic acid solution of silicon dioxide. 5. The method for producing a silicon oxide-coated optical information recording medium according to claim 3, wherein the silicon oxide coating is deposited over the entire surface of the optical information recording medium.