JPH0447913B2 - - Google Patents

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.

2. Description of the Related Art In recent years, as optical electronics technology has progressed, optical recording systems that use laser light to record and reproduce information have been attracting attention.

Optical recording systems are capable of carrying extremely high-density information in the medium, and because they are non-contact reading, the recording medium has excellent durability and has the characteristics of being able to perform random access at high speed. The background to this is the fact that

Optical recording systems can be roughly divided into (a) read-only type that copies a large amount of the same information, (b) write-once type that allows the user to write using a laser beam, and (c) a write-once type that allows the user to write using a laser beam. There is an erasable type that can erase the written signal and reuse it, and both use laser light to read out the signal.
A recording medium in the form of a card, tape, etc. is 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 transfers the signal using a plastic molding method such as injection molding or press molding of thermoplastic resin. , a reflective layer is formed on a concavo-convex signal-carrying surface, but an expensive molding machine is required, and there are many obstacles to forming a concavo-convex signal with high precision in such a molding method, resulting in poor yield. In addition, the formation of such a concavo-convex signal is as described above.
(b) Write-once type (c) Erasable type also requires the formation of recording position indicating signals, guide grooves, etc., and has the same production technology problems as the read-only type.

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 liquid resin between the substrate material and the stamper and curing it, as disclosed in Japanese Patent Application Laid-Open No. 57-47625, but this method has drawbacks such as difficulty in removing air bubbles and easy mixing of fine dust. be.

There is also a method of forming a plastically deformable, photocurable recording signal carrying layer on a substrate material in advance, as disclosed in Japanese Patent Application Laid-Open No. 57-133533, and then transferring the uneven signal of the stamper using a press. However, it has the disadvantage that it is difficult to maintain uniformity of press pressure.

The present invention overcomes the drawbacks of the prior art as described above and provides a novel method for manufacturing an optical recording medium, which is characterized in that uneven recording signals can be transferred at low cost and with a low defect rate. It is something.

That is, the present invention forms a recording signal carrying layer made of a resin component that is deformable by pressure, has no tackiness at room temperature, and can be crosslinked by irradiation with active energy rays on a transparent support, Stampers engraved with a concavo-convex signal are superimposed, and the concave-convex signal is transferred to the recording signal carrying layer under reduced pressure of 10 Torr or less, and active energy rays are irradiated to produce a recorded signal with the concavo-convex signal transferred thereto. This is a method for producing an optical recording medium, characterized by crosslinking and curing a support layer.

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 since plastic deformation must not occur during transfer of the recorded signal, the heat deformation temperature must be low. The temperature is 50℃ or higher, preferably 80℃ or higher, and the thickness is 25℃ to improve adhesion to the stamper.
~500 μm is preferred, particularly 50 ~ 200 μm.

Examples of the above supports include resin films or sheets of polyester, polycarbonate, polymethacrylate, polystyrene, vinyl chloride, polyester sulfon, polyether sulfon, polyamide, polyimide, cellulose acetate, cellulose butyrate, etc. It is not limited to resin.

The recording signal carrying layer of the present invention is a layer that does not have adhesiveness at room temperature, can be crosslinked by irradiation with active energy rays such as ultraviolet rays, electron beams, and gamma rays, and can be deformed by pressure. It is formed by dissolving a resin component such as in an organic solvent, coating it on the support, and then evaporating off the organic solvent. However, if the layer is sticky at room temperature, it is undesirable because dust and the like tend to adhere to it, increasing the probability of recording dropouts.

At least a portion of the resin component used as the recording signal carrying layer may be crosslinked by active energy rays, and the remaining portion may be a non-crosslinkable resin component. In order for the above resin component to have a structure that can be crosslinked by active energy rays, (1) an ethylenically unsaturated double bond is introduced into the terminal or side chain of the resin, and free bonds generated by active energy rays are introduced. (2) A method in which allylic double bonds are introduced into the terminal or side chain of the above resin, and the addition reaction with the thiol group is carried out by the coexistence of a thiol-containing compound using active energy rays. (3) A method in which a thiol group is introduced into the terminal or side chain of the above resin, and the resin-forming component having an allylic double bond is additionally crosslinked when irradiated with active energy rays. (4) ) There is a method in which an epoxy group is introduced into the terminal or side chain of the resin, and cationic ring-opening polymerization of the epoxy group is carried out using a sensitizer that liberates a Lewis acid using active energy rays to effect crosslinking.

It is desirable that the crosslinkable resin component mentioned above has a number average molecular weight of 2000 or more. If it is less than this, the recording signal carrying layer of the present invention becomes sticky, and if the stickiness is removed, cracking and peeling tend to occur, which is not preferable.

In such a case, it is preferable to mix and use a resin having a number average amount of 5000 or more (the resin component may be non-crosslinkable to active energy rays). In addition, 40% by weight or more of the total resin components of the recording signal carrying layer, especially
It is desirable that 60% by weight or more is a crosslinkable resin component.

Examples of the non-crosslinkable resin component that can be used in combination with the crosslinkable resin component include acrylic resin, polyester resin, polyurethane resin, polyamide resin, styrene copolymer resin, vinyl chloride resin, polyvinyl butyral resin, cellulose acetate, cellulose butyrate,
Examples include cellulose derivatives such as nitrocellulose, phenoxy resins, etc., but resins other than the above may be used as long as they are compatible with the crosslinkable resin component and have a number average molecular weight of 5000 or more as described above. I can't really use it.

In the present invention, a concavo-convex signal is transferred to the recording signal-bearing layer, and the recording signal-bearing layer to which the signal has been transferred is crosslinked by irradiating active energy rays through the support. As the radiation, ultraviolet rays, electron beams, gamma rays, etc. are used, and among these, ultraviolet rays are most preferable from the point of view of the simplicity of the apparatus. In this case, in addition to the above-mentioned resin components, it is common to use a photosensitizer that is activated by ultraviolet irradiation. By irradiating the photosensitizer (b) with ultraviolet rays,
There are photosensitizers that generate Lewis acids, and examples of sensitizers belonging to (a) include benzophenones such as benzophenone and chlorobenzophenone; anthraquinones such as ethyl anthraquinone; benzoin,
Examples include benzoins such as benzoin methyl ether, benzoin ethyl ether, and benzoin isobutyl ether; acetophenones such as diethoxyacetophenone and dihydroxyacetophenone; thioxanthone such as chlorthioxanthone; and benzyl ketals. Examples of sensitizers belonging to this group include diazonium salts, sulfonium salts, and iodonium salts of Lewis acids such as boron fluoride ions and phosphorus fluoride ions. The proportion of the photosensitizer to be used is preferably 1 to 5% by weight based on the resin component.

However, when the energy beam used for crosslinking is an electron beam or gamma ray, a photosensitizer does not necessarily need to be used in combination.

In addition, in addition to the above-mentioned crosslinking resin components and non-crosslinking resin components, auxiliary agents such as plasticizers, mold release agents, surface smoothing agents, adhesion improving agents, antifoaming agents, etc. may be used in combination for recording. A signal carrying layer may also be formed.

In the present invention, the stamper carrying the unevenness signal may of course be a metal stamper used in conventional molding methods, but it is possible to use a stamper with unevenness on the mirror surface.
Any hard material having a diameter of 0.05 μm or more, preferably 0.1 to 0.3 μm can be used. For example, a so-called photomask made of glass chrome, which is made by etching chromium-deposited glass using a photoresist method, can also be used as a stamper. The production becomes extremely easy.

The stamper having the above-mentioned uneven signal is stacked on the recording signal carrying layer and brought into close contact with the recording signal carrying layer under vacuum (under reduced pressure) to remove air between the stamper and the recording signal carrying layer. The indentation and unevenness signals of the stamper are transferred. The degree of vacuum at this time is preferably 10 torr or less. If it exceeds 10 torr, the transfer is insufficient,
In particular, it is preferably 5 torr or less. Further, the transferability can be further improved by applying heat during the close contact or applying air pressure from the outside of the optical recording medium and/or the stamper at the same time as the vacuum contact to further increase the degree of close contact. In particular, applying air pressure from the outside improves the uniformity of transfer, and this effect is observed even at a pressure of 0.5 kg/cm ² .

In order to crosslink and harden the carrier layer to which the uneven signal has been transferred, the uneven signal of the stamper may be transferred to the recording signal carrying layer as described above, and active energy rays may be irradiated while the stamper is in close contact with the stamper, or the stamper may be removed. After molding, active energy rays may be irradiated. When irradiating active energy rays while the stamper is in close contact with the stamper, it is usually irradiated from the side of the support, but if the stamper can transmit the active energy rays, irradiation may be performed from the stamper side. When used as a stamper, active energy rays may be irradiated from the stamper side to crosslink the recording signal carrying layer corresponding to the active energy ray transparent areas, and after demolding, active energy rays may be irradiated once again to crosslink the uncrosslinked areas. good. Further, when irradiating active energy rays after demolding from the stamper, the active energy rays may be irradiated from either side of the recording signal carrying layer or the support.

A mercury lamp, a high-pressure mercury lamp, a metal halide lamp, a xenon arc lamp, a xenon mercury arc lamp, etc., which generate ultraviolet rays or far ultraviolet rays, are used as the source of the above-mentioned active energy rays for crosslinking the recording signal carrying layer. The amount of far ultraviolet rays irradiated is usually 50 mJ or more, preferably 100 to 1000 mJ/cm ² .

Further, electron beams and gamma rays are also effective for crosslinking, and the recording signal carrying layer is crosslinked by irradiation with a crosslinking dose of usually 1 megarad or more, preferably 2 to 20 megarads.

Since the recording signal carrying layer of the present invention is cross-linked and cured as described above, the engraved uneven signal will not be deformed by heat, and the signal will not be deformed due to scratches. Since there are no scratches, a highly durable optical recording medium can be obtained.

When the optical recording medium in which the concavo-convex signal has been transferred and the recording signal carrying layer has been crosslinked as described above is used as a read-only optical recording medium, a reflective layer made of aluminum or the like is provided on the recording signal carrying layer. It is formed using a vapor deposition technique known per se, and if necessary, a protective layer of the reflective layer is painted or laminated with other materials for practical use.

Furthermore, when used as a recordable or erasable optical recording medium, recording position display signals and unevenness signals corresponding to guide grooves can be transferred and formed in exactly the same way, and the unevenness signal-bearing surface can be further imprinted on the user's side. For example, tellurium, tellurium carbon,
Various metal-based recording layers such as tellurium-bismuth alloy, tellurium low oxide, antimony-selenium alloy, bismuth, titanium, chromium, indium, manganese-bismuth alloy, gadolinium alloy, etc. are formed in one or multiple layers by vapor deposition, or by laser light. Various organic compounds such as polymethine dyes, dithiol metal complex dyes, phthalocyanine complexes, and porphyrin metal complexes that absorb energy and convert it into heat are vapor-deposited or coated with a binder material for film formation to form a recording layer and used as an optical recording medium. It is offered to

As mentioned above, the method for manufacturing 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 significantly reduced. In addition, since the transferred concavo-convex signals are photocured, it is possible to form a highly durable recording signal carrying layer.

The present invention is particularly useful when a flexible film or sheet is used as the transparent support.

EXAMPLES The present invention will be specifically explained below with reference to Examples.

Example 1 A copolymer consisting of 80% by weight of methyl methacrylate and 20% by weight of ethyl acrylate (weight average molecular weight: 35,000) was placed on a 75 μm thick polyester film.
70 parts by weight, 30 parts by weight of trimethylolpropane triacrylate, and 3 parts by weight of benzoin ethyl ether, which is a photosensitizer, were dissolved in 200 parts by weight of toluene, and coated with a gravure coater so that the dry film thickness was 5 μm. and dried at 80℃ for 20 minutes to form a non-adhesive recording signal carrying layer, which was then dried at 150mm x
Cut into 150mm square size.

Next, using chromium-deposited tempered glass as a base material, the concave-convex signals corresponding to the audio signals are applied to a positive photoresist film, exposed, developed, chromium film etched, and resist film peeled off using conventional photoresist methods. Then, a stamper was created. The gap between the unevenness is 0.2μm, and the width of the signal is
The track spacing was 1.6 μm.

Lay the above stamper and recording signal carrying layer side together, place a tempered glass mirror plate on the polyester film side, bring the stamper and recording signal carrying layer side into close contact under a reduced pressure of 3 torr, and apply compressed air to a pressure of 2 kg/cm ² on the mirror plate. After that, ultraviolet rays were irradiated at 500 mJ/cm ² using a 2 KW high-pressure mercury lamp through a mirror plate. After releasing the pressure and vacuum and demolding, vacuum evaporation of aluminum is applied to the surface of the recording signal carrying layer.
A reflective layer was formed. The gap in the unevenness of the recording signal measured from the reflective layer side was 0.19±0.01 μm, and there was no change in the shape of the uneven signal even after heating at 100° C. for 1 hour.

The above optical recording medium was punched out into a disk shape with a diameter of 120 mm, 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 In place of the recording signal carrying layer components in Example 1, 80 parts by weight of a copolymer (weight average molecular weight 20,000) consisting of 50% by weight of methyl methacrylate and 50% by weight of glycidyl methacrylate, and diglycidyl bisphenol A were used. 20 parts by weight of ether and 2 parts by weight of triphenylsulfonium 6-difluoride as a photosensitizer are dissolved in 150 parts by weight of methyl ethyl ketone,
Coat it on a 75 μm thick polyester film using a gravure coater so that the dry film thickness is 3 μm.
It was dried at 80° C. for 10 minutes to form a non-tacky record carrier layer.

Hereinafter, in exactly the same manner as in Example 1, the recorded signal was transferred and irradiated with ultraviolet rays, and a reflective layer was formed to produce an optical recording medium of the present invention, and the same audio signal was reproduced. As a result, good audio was obtained. I was able to play the .

The gap in the unevenness of the recording signal measured from the reflective layer side was 0.18 μm±0.01 μm, and no change in the shape of the uneven signal was observed even after heating at 100° C. for 1 hour.

Example 3 In place of the recording signal carrying layer components in Example 1, a polyester resin (weight average molecular weight 6000) having a terminal thiol group synthesized from 1 mol of phthalic anhydride, 0.6 mol of trimethylolpropane, and 0.2 mol of thioglycolic acid was used. 85 parts by weight of triallylisocyanurate, 15 parts by weight of triallylisocyanurate, and 3 parts by weight of diethoxyacetophenone as a photosensitizer were dissolved in 150 parts by weight of methyl ethyl ketone, and the mixture was coated with a gravure coater.
Dry film thickness on 75μm polyester film
It was applied to a thickness of 2 μm and dried at 80° C. for 10 minutes to form a non-adhesive recording signal carrying layer.

The optical recording medium of the present invention was prepared by transferring the recorded signal and irradiating it with ultraviolet rays in exactly the same manner as in the example, and by forming a reflective layer.As a result of reproducing the same audio signal, good audio was obtained. I was able to play the .

The gap between the unevenness of the recorded signal measured from the reflective layer side was 0.18μm±0.01μm, and even after heating at 100°C for 1 hour, the unevenness signal remained unchanged. No change in shape was observed.

Example 4 A non-adhesive recording signal carrying layer was formed on a polyester film support in exactly the same manner as in Example 1 except that the photosensitizer benzoin ethyl ether was removed from the recording signal carrying layer forming components. The unevenness signal of the stamper was transferred under the same conditions as in Example 1, the stamper was removed from the stamper without irradiation with ultraviolet rays, and then electron beam irradiation was performed from the surface of the recording signal carrying layer. The electron beam irradiation was carried out under the conditions of an applied voltage of 200 KV, a current density of 10 mA, and 5 megarads. Subsequently, a reflective layer was formed in the same manner as in Example 1 to produce an optical recording medium of the present invention, and the same audio signal was reproduced. As a result, good audio reproduction was achieved.

The gap in the unevenness of the recording signal measured from the reflective layer side was 0.18 μm±0.01 μm, and no change in the shape of the uneven signal was observed even after heating at 100° C. for 1 hour.

Example 5 The optical recording medium of the present invention was produced in exactly the same manner as in Example 1, except that only pressurization with compressed air was not performed in the signal transfer step, and the same audio signal was reproduced. , we were able to perform good voice re-voicing. The gap between the unevenness of the recording signal measured from the reflective layer was 0.15 μm ± 0.02 μm, and the temperature was 100°C.
No change in the state of the unevenness signal was observed even after heating for 1 hour.

Comparative Example An optical recording medium was prepared in exactly the same manner as in Example 5 except that the reduced pressure conditions were adjusted to 12 Torr, and as a result of reproducing an audio signal, noise was generated partially.

The gap in the unevenness signal measured from the reflective layer side is
The difference was 0.10μm±0.04μm, and it was assumed that the noise was caused by variations in the uneven gap.

Claims (1)

[Claims] 1. A recording signal carrying layer made of a resin component that can be deformed by pressure, has no tackiness at room temperature, and can be crosslinked by irradiation with active energy rays is formed on a transparent support, and a concavo-convex signal is engraved. The stampers are stacked together, and the uneven signal is transferred to the recording signal carrying layer under a reduced pressure of 10 torr or less, and the recording signal carrying layer to which the uneven signal is transferred is cross-linked by irradiating active energy rays. A method for producing an optical recording medium, which comprises curing the medium.