JPS60167146A - Production for optical recording medium - Google Patents

Abstract

PURPOSE:To produce inexpensively an optical recording medium having a rugged signal with a low fraction defective by transferring rugged signals to a recorded signal bearing layer, which consists essentially of a plastic resin, at a temperature higher than the temperature where this resin can be deformed plastically. CONSTITUTION:A recorded signal bearing layer 30 consisting essentially of a thermoplastic resin which has not viscosity at a normal temperature but can be deformed plastically at a temperature higher than the normal temperature and lower than 80 deg.C is formed on a transparent supporting body 40. A stamper 60 provided with rugged signals is put on this layer 30, and rugged signals are transferred to the recorded signal bearing layer at a temperature higher than the temperature, where said resin can be deformed plastically, under pressure reduction of <=10Torr to produce the optical recording medium. Signals are transferred at a temperature higher than the temperature, where the recorded signal bearing layer can be deformed plastically, by 20-50 deg.C, concretely, at 20-130 deg.C. If signals are transferred at a temperature exceeding this temperature, the supporting body is deformed to degrade productivity. Since this production method is very easy and the adhesive strength between the stamper and the recorded signal bearing layer is improved considerably, a fraction defective of products is reduced considerably.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of manufacturing an optical recording medium having an optically readable uneven signal.

Therefore, optical recording systems that use laser light to record and reproduce information are attracting attention.

Optical recording systems can carry extremely high-density information in the medium, and since they are non-contact reading, the recording medium has excellent durability and can be randomly accessed at high speed. is the background.

Optical recording systems can be roughly divided into (a) read-only types that make large copies of the same information; (b) write-once types that allow the user to write using a laser beam; and (c) write-once types that write using a laser beam and write to the user. There is an erasable type that can erase and reuse the signal, and both use laser light to read the signal, and there are recording media in the form of disks, cards, tapes, etc. used.

The read-only type described in (a) above uses a mold called a stamper that converts recorded information into a concave-convex signal, and molds thermoplastic resin by injection molding, press molding, etc.
Although it is manufactured by forming convex signals between the interfacial surfaces, it requires an expensive molding machine, and it is difficult to form the convex and convex signals with high precision in such a molding method. has many obstacles and low yield. In addition, the formation of such uneven signals requires the formation of recording position display signals, guide grooves, etc. even in the (b) write-once type and (c) erasable type, which poses the same production technology problems as the read-only type. have.

In addition to forming unevenness signals on the substrate material itself by injection molding, press molding, etc., as described above,
There is a method of inserting a liquid resin between a substrate material and a stamper and curing it as disclosed in Japanese Patent No. 7625, but this method has drawbacks such as difficulty in removing air bubbles and easy mixing of fine dust.

There is also a method of forming a plastically deformable photo-curable recording signal supporting layer on a substrate material in advance, as disclosed in Japanese Patent Application Laid-Open No. 57-133533, and then transferring the unevenness signal of the stub bar by pressing. However, there is a drawback that it is difficult to maintain uniformity of press pressure.

The present invention overcomes the drawbacks of the prior art as described above, and makes it possible to transfer uneven recording signals at low cost and with a low defect rate. The present invention provides a method for producing a novel optical recording medium having the following characteristics.

That is, the present invention forms on a transparent support a recording signal-bearing layer mainly composed of a thermoplastic resin that is sticky at room temperature and can be plastically deformed at temperatures above room temperature and below 80° C. This method of manufacturing an optical recording medium is characterized in that the unevenness signal is transferred to the recording signal carrying layer at a temperature above the plastic deformation temperature and under reduced pressure below 10 Torr.

The material of the transparent support used in the present invention is not limited in principle as long as it is a transparent plastic sheet or film, but it must not undergo plastic deformation during transfer of the recorded signal, so the heat deformation temperature is low. 50℃ or higher, preferably 8
The thickness is preferably 25 to 500 μm, especially 50 μm in order to maintain a temperature of 0° C. or higher and improve adhesion with the stand bar.
~200 μm is preferred.

As the above-mentioned support, for example, resin films or sheets of polyester, polycarbonate, polymethacrylate, polystyrene, vinyl chloride, polyester sulfone, polyether sulfone, polyamide, polyimide, cellulose acetate, cellulose butyrate, etc. are used. It is not limited to resin.

The recording signal supporting layer of the present invention has adhesiveness at room temperature of 80%.
It is made of a plastic resin that can be plastically deformed at a temperature of 0.degree. If it is sticky at room temperature, it will easily attract dust etc. (this is not desirable as it will increase the probability of recording dropouts. Also, if it cannot be plastically deformed at 80°C or below, signal transfer due to vacuum adhesion will be poor). This is inappropriate.

Usually, the signal transfer according to the present invention is carried out by 20 to 50°C above the temperature at which the recording carrier layer can be plastically deformed (room temperature or higher and 80°C or lower).
0℃ higher temperature specifically 20~160℃ preferably 20℃
Performed at ~80°C. If the eaves tile is made with a higher level of enthusiasm than this, it is not desirable because -F-hi's old mochita type 9 may occur or productivity will decrease.

The thickness of the recording layer described above may be 0.5 μm or more, but is generally 1 to 20 μm.

The plastic resin used for the recording signal carrying layer in the present invention is not limited in any way as long as it is soluble in an organic solvent and satisfies the above conditions, but examples include styrene copolymer resin, acrylic copolymer resin, etc. , epoxy resins, polyester resins, vinyl acetate copolymer resins, cellulose derivative resins, polyurethane resins, polyvinyl butyral resins, etc. are common, and two or more of these resins may be used in combination, and plasticizers, mold release agents, surface Auxiliary agents such as a smoothing agent, an adhesion improving agent, and an antifoaming agent may be used in combination.

Since it is inconvenient for these plastic resins to cause cracks or cracks when handling the optical recording medium, it is preferable to use one having a weight molecular weight of 5,000 or more as the main component, and the content thereof is limited to that of the recording support layer. 80% by weight
It is preferable to do the above.

In the present invention, the stamper carrying the unevenness signal may be a metal stamper used in conventional molding methods, but it is a hard stamper having an unevenness gap of 0.05 μm or more, particularly preferably 0.1 to 0.3 μm. Any material can be used as a stamper. For example, a chromium-deposited glass etched by a photoresist method or a chromium-based photomask can also be used as a stamper, making the production of the stamper extremely easy.

Transferring the unevenness signal, that is, incorporating the signal into the recording signal carrying layer of the present invention, is carried out as shown in FIG.

That is, a recording signal supporting layer 30 and a transparent support 40 are placed in a vacuum container 20 that can be made airtight with a vacuum gasket 10.
A recording medium 50 made of the above is set overlappingly with a stamper 60.

That is, the surface portion 65 of the stamper 60 having a concavo-convex signal and the recording signal-bearing layer 60 are superimposed, and the inside of the container is evacuated by a vacuum pump (not shown) through a perforated plate or mesoche-like partition plate 70 at the bottom of the vacuum container. Apply vacuum (reduced pressure) to bring the stamper and signal-carrying layer into close contact. As the exhaust volume is increased to remove the air between the meta/par and the recording signal supporting layer, and the degree of depressurization is also increased, the recording signal supporting layer is reliably infiltrated into the stamper, and the uneven signals of the stamper are transferred to the support layer by plastic deformation. If the degree of vacuum at this time exceeds 10 Torr, the transfer will be insufficient, so it is particularly preferable to keep it below 5 Torr.In addition, heat may be applied during the close contact, or air pressure may be applied at the same time as the vacuum contact as shown in the figure. Transfer performance can be further improved by applying air pressure from the outside and pressing the recording medium with a stamper.In particular, applying air pressure from the outside improves the uniformity of the transfer (0.5Ky/cA). This effect is also observed in pressure.

After transferring the concavo-convex recording signal as described above, the optical recording medium is removed from the stamper, and if the optical recording medium is to be used as a read-only optical recording medium, a reflective layer of aluminum or the like is formed using vapor deposition technology. If necessary, a protective layer of a reflective layer is formed by painting or laminating with a low-quality material, and the optical recording medium can be put to practical use.

In addition, in the case of write-once or erasable optical recording media, the recording position display signal and the uneven signal corresponding to the guide groove can be transferred in exactly the same way, and the uneven signal can be transferred after being removed from the stamper. On the support surface, there are various kinds of materials such as tellurium, tellurium-carbon, tellurium-bismuth alloy, tellurium low oxide, antimony selenium alloy, bismuth, titanium, chromium, indium, manganese-bismuth alloy, gadolinium alloy, etc., which becomes a recording layer on the user side. The metal recording layer can be formed into a single layer or multiple layers by vapor deposition, or various organic compounds that absorb laser light and convert it into heat, such as polymethine dyes, dithiol metal complex dyes, phthalocyanine metal complexes, and porphyrin metal complexes, can be formed by vapor deposition or It is used by coating it together with a film-forming binder material to form a recording layer.

As mentioned above, the manufacturing method of the optical recording medium of the present invention is extremely simple as no equipment such as a press is required, and the adhesion between the stamper and the recording layer is greatly improved, so the defective rate of the product is reduced. The present invention is useful when a flexible film or sheet is used as a transparent support.

Hereinafter, the present invention will be specifically explained with reference to Examples.

Example 1 On a polyester film with a thickness of 75 μm, methyl methacrylate and ethyl acrylate copolymer (thermal deformation initiation temperature in TMA method: 45° C., weight average molecular weight: 420,000) was dissolved in toluene to make a 30% by weight solution. It was coated with a gravure coater so that the dry film thickness was 5 μm, and dried at 80° C. for 20 minutes to form a recording signal supporting layer.
It was cut to a size of 0m square.

Next, a chromium-deposited tempered glass is used as the base material, and a positive resist film is applied, exposed, and
A stamper was prepared by using conventional photoresist processes such as development, chromium film etching, and resist film peeling. The unevenness gap is 0.2μm, the signal width is 08μ+11, and the track spacing is 1.6μm.
Met.

Lay the above stamper and the recording signal supporting layer side together, place an aluminum mirror plate on the polyester film side, and press the stamper.
The surface of the recording signal carrying layer was brought into close contact with the surface of the recording signal carrying layer under a reduced pressure of 6 torr, the mirror plate surface was heated to 80°C using an infrared lamp, and compressed air 2 was heated.
The mirror plate was pressed for 2 minutes at a pressure of Ky/l:d to perform signal transfer. After releasing the pressure and vacuum and demolding, aluminum was vacuum-deposited on the surface of the recording signal supporting layer to form a 600A reflective layer.

The gap between the unevenness of the recording signal measured from the reflective layer side is
It was 0.19 μm±0.01 μm.

The above optical recording medium was punched out into a disk shape with a diameter of 120M, and the audio signal was reproduced using a player equipped with a semiconductor laser optical head. As a result, good audio reproduction was achieved.

Example 2 An optical recording medium was produced in exactly the same manner as in Example 1 except that compressed air pressure was not applied. The gap between the unevenness measured from the reflective layer side was 0.15 μm±0.02 μm.

Sound was reproduced in the same manner as in Example 1, and as a result, good sound reproduction was achieved.

Example 6 An optical recording medium was produced in exactly the same manner as in Example 1 except that the compressed air pressure was 0.8 Kg/c4.

The gap between the unevenness measured from the reflective layer side is 0.18μm
The difference was ±0.01 μm, and as a result of the same sound playback evaluation as in Example 1, it was possible to perform good sound playback.

Example 4 A polycarboy trilum with a thickness of 100 μm was used as a support, and 80 parts by weight of polyvinyl butyral resin (weight average molecular weight 12,000) and 20 parts by weight of dioctyl phthalate were dissolved in 500 parts by weight of ethyl acetate and a dried film was formed on the support. It was coated with a gravure coater to a thickness of 6 μm and dried at 80° C. for 20 minutes to form a recording signal carrying layer.

Although the temperature at which the recording signal carrying layer started thermal deformation was 5° C., there was no tackiness.

Using the stand bar described in Example 1, vacuum adhesion was performed with the same equipment as in Example 1, and compression was performed with compressed air of 2 kg/cd at room temperature, and a reflective layer was formed in the same manner as described in Example 1. An optical recording medium was created. The gap between the unevenness of the recorded signal was 0.17 μm±0.01 μm, and the results of audio reproduction evaluation were good.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing a method for manufacturing an optical recording medium of the present invention. Patent applicant Mitsui Toatsu Chemical Co., Ltd. No. 1 Diagram '70

Claims (1)

[Claims] 1. Forming on a transparent support a recording signal-bearing layer mainly composed of a plastic resin that is sticky at room temperature and can be plastically deformed at temperatures above room temperature and below 80°C; An optical recording medium characterized in that stub bars on which a concavo-convex signal is engraved are superimposed, and the concavo-convex signal is transferred to the recording signal carrying layer at a temperature above the plastic deformation temperature and under a reduced pressure of 10 Torr or less. Production method. 2. The method according to claim 1, wherein the transfer is performed at a temperature 20 to 50° C. higher than the temperature at which plastic deformation is possible. 3. The method according to claim 1 or 2, wherein the transfer is performed at 20 to 130°C.