JPH0740379B2 - Method for manufacturing thin optical memory medium - Google Patents

Description

The present invention relates to a method for manufacturing an optical memory medium, and more particularly to a method for manufacturing a grooved optical memory medium such as a flexible optical disk.

[Conventional technology]

A conventional thin optical memory medium is manufactured by molding a thermoplastic resin such as polymethylmethacrylate / polycarbonate by injection molding or compression molding so as to form an uneven guide groove on the surface, and then forming this substrate. This is done by stacking an optical recording layer on top.

With such a method, it is difficult to reduce the thickness and it is difficult to manufacture an optical memory medium having a thickness of 1.0 mm or less. As shown in FIG. 5, the substrate is an uneven guide groove portion.
In contrast to 51, the main reason is that unless the thickness of the base portion 52 therebelow is made considerably large, molding is difficult due to problems such as strength.

[Object of the Invention]

The present invention has been made in view of the above problems, and an object thereof is to provide a method by which a flexible optical disk or the like having a thickness of 1.0 mm or less can be manufactured more easily than before.

[Means for solving problems]

The above object of the present invention is to spread a thermoplastic resin in a plastic state on one surface or both surfaces of a heat resistant sheet, directly or through another layer, and transfer a concave and convex guide groove to the resin. On the other hand, it is achieved by adhering and solidifying to a heat-resistant sheet, and then laminating an optical recording layer recordable by optical energy on the surface having the uneven guide groove.

Hereinafter, examples of the present invention for producing a thin optical memory medium having an optical recording layer on only one surface of a heat resistant sheet will be described in detail.

In this example, first, the master was electroformed to manufacture. A stamper having an uneven surface is installed on one inner surface of a pair of molds. Further, a heat resistant sheet is installed on the inner surface of the other mold or in a space where the molds face each other so as to face the stamper and face each other. Next, while the mold is being clamped, or after the mold is clamped, the resin in a plastic state is spread and spread throughout the space formed by the stamper and the heat-resistant sheet surface in the mold.
The resin has an uneven guide groove transferred to its surface by the stamper and adheres to and solidifies on the heat resistant sheet. In this way, the substrate is completed.

In the present invention, as a method of spreading the resin in a plastic state, a compression molding method in which a cured resin is compressed by a mold being clamped, and a casting method in which a liquid resin is injected into the clamped mold Method or an injection molding method of injecting a heated thermoplastic resin into a mold may be used.

Further, in the present invention, before the step of spreading the resin in a plastic state and adhering it to the heat-resistant sheet, in order to further improve the adhesive force thereof, a layer having a strong adhesiveness (adhesive layer) is previously formed on the heat-resistant sheet. It may be provided. This adhesive layer not only improves adhesion, but also protects the heat-resistant sheet.

Then, an optical recording layer is laminated on the surface of the substrate on which the guide groove exists, that is, the surface of the resin formed by spreading, by various coating methods such as vapor deposition, roll coating, and dip coating. Through the above steps, a thin optical memory medium can be manufactured.

The heat-resistant sheet used in the present invention, that is, the base film, withstands the temperature of the resin in the plastic state at the time of forming the uneven pattern, and is preferably a thermosetting heat-resistant film.
Typical examples of the thermosetting heat-resistant film include polyimide film, polyamideimide film, epoxy resin film, silicone resin film, polyesterimide film, polyester film, and tetrafluoroethylene-hexafluoropropylene copolymer film, tetra film. Examples thereof include fluororesin films such as fluoroethylene-perfluoroalkyl vinyl ether copolymer films.

A thermoplastic resin is preferred as the resin used in the present invention for forming the guide groove on the surface. Typical examples of the thermoplastic resin include polysulfone, polyolefin, polyolefin copolymers such as ethylene-vinyl acetate copolymer, ethylene-acrylate copolymer and ethylene-propylene copolymer, polyolefin halides, vinyl acetate. −
Vinyl chloride copolymer such as vinyl chloride copolymer and vinyl chloride-acrylonitrile copolymer, vinylidene chloride-vinylidene chloride copolymer and vinylidene chloride copolymer such as vinylidene chloride-vinyl chloride-acrylonitrile copolymer, Polystyrene, styrene copolymers such as styrene-acrylonitrile copolymer (AS resin) and styrene-acrylonitrile-butadiene copolymer (ABS resin), p-methylstyrene, 2,5-dichlorostyrene, vinylanthracene, etc. , Or their copolymers (styrene copolymers), coumarone and indene or copolymers of these with styrene, terpene resins or picolite, acrylic resins, polyacrylonitrile, acrylonitrile-
Acrylonitrile copolymers such as vinyl acetate copolymers, acrylonitrile-vinyl pyridine copolymers, acrylonitrile-methyl methacrylate copolymers, polyacrylamides, or diacetone acrylamide polymers obtained by reacting acetone with acrylonitrile, polyacrylonitrile. Vinyl acetate,
Copolymers of acrylic acid ester, vinyl ester, vinyl ether, ethylene, etc. and vinyl acetate, polyvinyl ether, polyamide, thermoplastic polyester, polyvinyl alcohol or polyvinyl acetal resin, polyurethane, polyvinylcarbazole or vinylcarbazole having a number average molecular weight of 6,000 or less. And a nitrogen-containing vinyl polymer such as a polyvinylcarbazole copolymer with ethylene or styrene, a polyene or a diene polymer such as a butadiene-styrene copolymer or an isoprene-isobutylene copolymer, a polyether, a polycarbonate,
Examples include polyethyleneimines, cellulosic resins, blends of two or more of the above resins, and blends with other thermoplastic resins.

The material of the optical recording layer used in the present invention may be of any type as long as it can form a thin film to be recorded by light, and examples thereof include metals such as aluminum, bismuth, inorganic materials such as tellurium oxide and chalcogenide compounds. Compounds. These materials are generally used as an optical recording layer by sputtering or vacuum evaporation. Other optical recording materials include those mainly containing a light absorbing dye. Examples of the light absorbing dye include cyanine, merocyanine, triphenylmethane, naphthoquinone, xanthene, squalium and azulene, azo, stilbene,
Phthalocyanine direct dye, azo, anthraquinone,
Triphenylmethane, xanthene, azine type acid dye, cyanine, azo, azine, triphenylmethane type basic dye, azo, anthraquinone, xanthene, triphenylmethane type mordant / acid mordant dye, anthraquinone, indigoid type Dyes, azo, anthraquinone, phthalocyanine, triphenylmethane-based oil-soluble dyes and the like can be used. These are mainly used as the optical recording layer by the various coating methods described above.

In order to manufacture a thin optical memory medium having optical recording layers on both sides by the method of the present invention, a pair of dies having stampers arranged on the inner surfaces thereof may be used. The method is shown in Example 2 below. An optical memory medium having optical recording layers on both sides has a large amount of information to be stored per sheet, is economical, and has a symmetrical shape on the front and back sides.

[Action]

In the method of the present invention, the guide groove portion and the base portion below the guide groove portion are formed of different materials to form the substrate, and since a high-strength heat-resistant sheet preformed on the base portion is used, the base portion is formed. The substrate can be easily formed without making the thickness relatively thicker than the guide groove portion. Therefore, according to this method, it is possible to reduce the thickness of the optical memory medium as a whole.

〔Example〕

Specific examples of the present invention will be shown below with reference to FIGS. 1, 2, 3 and 4, and the present invention will be described in more detail.

Example 1 In FIG. 1, a stamper 2 having an uneven surface, which was manufactured by subjecting a master to electroforming, was installed in one mold 3, and a polyimide tape having a heat softening temperature of 300 ° C. or higher and a thickness of 50 μm. Was placed on the other mold 4 as the heat-resistant sheet 1. A polymethylmethacrylate resin 5 having a number average molecular weight of 80,000 in a softened and plastic state was supplied to the center of the stamper 2, and the resin 5 was compressed by the molds 3 and 4. The resin 5 flows from the center of the mold to the peripheral direction and spreads throughout the mold as shown in FIG.
Thus, an uneven guide groove was formed on the surface.

Light absorbing dye with the following structural formula 1% solution (solvent: diacetone alcohol: isopropyl alcohol = 2: 1 parts by weight) on the resin having the guide groove formed by a roll coating method, and then the solvent is evaporated to form an optical recording layer, A thin optical memory medium is obtained.

Example 2 In FIG. 3, two stampers 22 having an uneven surface, which were produced by subjecting a master to electroforming, were installed on both sides of a mold 23, respectively, and the heat softening temperature was set between the two stampers 22. A polyimide tape having a thickness of 300 ° C. or more and a thickness of 50 μm was arranged as the heat resistant sheet 21. A softened polymethylmethacrylate resin 24 having a number average molecular weight of 80,000 is supplied to both sides near the center of the heat-resistant sheet 21, and the resin 24 and the heat-resistant sheet 21 are molded into a mold.
Compressed from both sides with 23. The resin 24 flows from the center of the mold to the peripheral direction and spreads throughout the mold as shown in FIG.
Simultaneously with bonding to the heat resistant sheet 21, the stamper 22 formed a guide groove in the shape of an uneven pattern on the surface thereof. The same light-absorbing dye solution as in Example 1 was then laminated on both surfaces of the substrate thus formed by dipping coating, and the solvent was evaporated to obtain an optical memory medium.

The thickness of the memory medium completed in Examples 1 and 2 was as follows.

Thickness (μm) Example 1 90 2 130 [Effect of the invention] As described above, the thermoplastic resin in the plastic state is spread on one surface or both surfaces of the heat-resistant sheet directly or through another layer. By extending and guiding the resin to form a concave-convex guide groove and adhering and solidifying it to a heat-resistant sheet, and then laminating an optical recording layer recordable by optical energy on the surface having the concave-convex guide groove. As a result, flexible optical discs with a thickness of 1.0 mm or less can be easily manufactured.

[Brief description of drawings]

FIG. 1 is a sectional view showing a state in which a resin in a plastic state is supplied to one side of a heat resistant sheet, and FIG. 2 is a sectional view showing a state in which the resin is spread in a mold. FIG. 3 is a sectional view showing a state in which a resin in a plastic state is supplied to both surfaces of the heat resistant sheet, and FIG. 4 is a sectional view showing a state in which the resin is spread in a mold. FIG. 5 is a sectional view of a substrate molded by the injection molding method. 1, 21: Heat resistant sheet, 2, 22: Stamper 3, 4, 23: Mold, 5, 24: Resin 51: Guide groove part, 52; Base part

Claims (5)

[Claims] 1. A heat-resistant sheet on one side or both sides,
A thermoplastic resin in a plastic state is spread directly or through another layer, and an uneven guide groove is transferred and formed on the resin while being adhered and solidified on a heat-resistant sheet. After that, an uneven guide groove is provided. A method for manufacturing a thin optical memory medium, comprising laminating an optical recording layer capable of recording with light energy on a surface thereof. 2. The method for producing an optical memory medium according to claim 1, wherein the resin in a plastic state is spread by a compression molding method. 3. The method for producing an optical memory medium according to claim 1, wherein the resin in a plastic state is spread by a cast molding method. 4. The method for producing an optical memory medium according to claim 1, wherein the resin in a plastic state is spread by an injection molding method. 5. The method of manufacturing an optical memory medium according to claim 1, wherein the heat resistant sheet is made of a thermosetting resin.