JP3223989B2 - Manufacturing method of optical recording medium - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a read-only optical recording medium.

[0002]

2. Description of the Related Art In recent years, read-only optical recording media such as compact discs have become popular. In this method, information is given to a stamper in advance so that the information is included in the recording medium, and the information is transferred by injection molding and the recording medium is manufactured. By this method, the same contents are produced in large quantities.

On the other hand, studies are being made on a read-only optical card. In this case, as in the above, an optical card is manufactured after a stamper having information is once manufactured.

[0004]

However, a stamper for an optical recording medium is manufactured through a complicated manufacturing process. In addition, a large amount of production is required to reduce the unit price per optical recording medium. If it is necessary to send and store information on a small amount of recording media (including one),
Production from stampers is not valid.

On the other hand, it is conceivable to record information on a write-once type optical recording medium and then take measures to prevent recording.
Write-once optical recording media are often inferior in durability and / or light resistance as compared with read-only optical recording media. In particular, when the organic recording material is used for the recording layer, the tendency becomes remarkable.

SUMMARY OF THE INVENTION The present invention has been made in order to improve such disadvantages of the prior art, and an object of the present invention is to provide a method for manufacturing a read-only optical recording medium having good durability, light resistance and reflectance. It is the purpose. Another object of the present invention is to provide a method for easily producing the above-mentioned read-only optical recording medium.

[0007]

That is, the present invention relates to a method for manufacturing an optical recording medium for reproduction having a recording layer comprising a thin film organic layer on a substrate, wherein the recording layer comprising an organic material is formed on the substrate. A method for producing an optical recording medium, comprising: performing writing on the recording layer using a laser, and holding the recording layer under heating and humidification conditions for 10 hours or more.

Further, the present invention provides a method of forming a track guide groove on a substrate by using a photocurable resin, forming a recording layer made of an organic material thereon, and writing the recording layer using a laser. A method for producing an optical recording medium according to the above, wherein the treatment is performed by the above-mentioned production method.

DETAILED DESCRIPTION OF THE INVENTION The present invention will be described in detail below. According to the present invention, in an optical recording medium, for example, an optical card or the like, before writing into a card form, writing is performed using a laser on a recording layer composed of a thin organic layer. After performing, after performing stabilization of the recording layer, by performing close lamination,
A read-only optical card can be created.

In the present invention, among the organic materials forming the recording layer, cyanine dyes are preferable for stabilizing the recording layer under high temperature and high humidity after writing using a laser. By stabilizing the recording layer under high temperature and high humidity, the recording layer of the organic compound provided on the substrate is changed,
A recording layer having high light resistance and durability can be obtained while increasing the reflectance.

A method for stabilizing the recording layer under high temperature and high humidity is as follows.
It is carried out by a method of holding at 50 ° C. or more, preferably 60 to 75 ° C., at 75% RH or more, preferably 80 to 90% RH for 10 hours or more.

In the present invention, the optical gap, the optical card and the like are higher in recording sensitivity in the air gap type than in the close-sealing type. / Reflectance of unrecorded portion].

It has been found that if the lower layer on which the recording layer is formed at the time of recording has high hardness and good thermal stability, the recording sensitivity after bonding is extremely reduced.

As described above, a high contrast can be obtained at the time of writing, and the reflectance increases in the unrecorded portion when the recording layer is stabilized. The contrast becomes higher than the contrast at the time.

[0015]

EXAMPLES The present invention will be specifically described below with reference to examples.

Example 1 0.4 mm thick P produced by a casting method
A recording layer having a thickness of 900 ° was formed on an MMA (polymethyl methacrylate) substrate using the following compounds. As a solvent, diacetone alcohol was used by a spin coating method.

[0017]

Embedded image

This is cut to the size of an optical card, and
Write at 3.5mW with 2μmφ spot, 0.2m
Playback with W, measure the recording and playback contrast,
0.74, and the unrecorded reflectance was 25%.

The above recording medium was heated to 65 ° C. and 85% RH for 2 hours.
When left for 0 hours, the reflectance of the unrecorded portion was 32%, and the reproduction contrast was 0.80. The recording medium was bonded to a back material PMMA (thickness: 0.3 mm) using an adhesive (hot melt type EMMA system) to produce a close-sealed optical card.

The reproduction contrast of the contact-sealing type optical card is 0.79, the continuous time of 0.2 mW laser irradiation has a decrease of 10% from the initial value of the reflectivity of 250 seconds, and the recording contrast is 0.25. Was. When left in an environment of 65 ° C. and 85% RH for 1000 hours, the reflectance was 30% to 2%.
8%.

Comparative Example 1 An optical card was prepared in the same manner as in Example 1 except that the step of leaving the substrate at 65 ° C. and 85% RH for 20 hours was omitted. Before bonding, the recording / reproducing contrast is 0.7
4. The reflectance of the unrecorded portion was 30%, but after bonding, the contrast was 0.72 and the reflectance of the unrecorded portion was 23.
%, The initial value of the reflectance of 10 with 0.2 mW laser continuous irradiation
% Reduction time was 25 seconds, and the recording contrast was 0.33.

Example 2 The compound shown in Example 1 was applied to an optical disk injection substrate made of polycarbonate (PC) by spin coating to form a recording layer having a thickness of 900 °. Attach this to a turntable and use a motor for 1800r
pm and a recording power of 8 m from the substrate side to the organic thin film recording layer using a semiconductor laser having an oscillation wavelength of 830 nm.
Information was written at W at a recording frequency of 3 MHz, reproduced at a read power of 0.8 mW, and the reproduced waveform was analyzed for spectrum (scanning filter, bandwidth 30 KHz) to measure the C / N ratio (carrier / noise ratio). In fact, it was 54 dB.

The recording medium was heated at 60 ° C. and 90% RH for 50 hours.
When left for a while, the regenerated C / N ratio was 56 dB. A backing PC substrate was adhered to this recording medium using an ethylene-vinyl acetate copolymer-based adhesive to obtain a tightly sealed optical disk. Regenerated C / N ratio after sealing is 55 dB,
54dB in repeatedly reproduced ¹⁰⁴ times, recording the C / N ratio is 26
dB.

COMPARATIVE EXAMPLE 2 A tightly sealed optical disk was produced in the same manner as in Example 1, except that the substrate was not left at 60 ° C. and 90% RH for 50 hours as shown in Example 2. This disc has a playback C / N ratio of 5 / d
B, 46 dB after 10 ⁴ repetitions, and the recording C / N ratio was 38 dB.

Example 3 The same experiment was carried out on the card shown in Example 1 except that a track guide groove was formed with a photocurable resin.

Initial writing is a recording / reproducing contrast of 0.7
2, unrecorded portion reflectivity 26%, 65 ° C, 85% RH, 20
After leaving for a time, the reflectance was 32% and the reproduction contrast was 0.77. This was bonded with PMMA (0.3 m thickness) to prepare an optical card. In this optical card, the reproduction contrast was 0.77, the time required for the decrease in reflectance due to continuous laser irradiation to decrease by 10% from the initial value was 230 seconds, and the recording contrast was 0.20. After 1000 hours of durability at 65 ° C. and 85% RH, the reflectance changed from 31% to 29%.

Example 4 A track guide groove was formed on a 0.4 mm-thick PC (polycarbonate) substrate with a photocurable resin, and then the following compound was spin-coated with dichloroethane to form a film having a thickness of 800 mm.
The recording layer of No. was formed.

[0028]

Embedded image

This reflectance is 28% in an unrecorded portion,
When recording was performed in the same manner as in Example 1, the recording / reproducing contrast was 0.75. When this was left at 60 ° C. and 80% RH for 50 hours, the reflectance was 35% and the reproduction contrast was 0.80 in the unrecorded portion.

An optical card was obtained by laminating with a PC (0.3 m thick) using a hot melt type EVA adhesive.
The reproduction contrast of this optical card is 0.78, 0.2m
With continuous W laser irradiation, the 10% reduction time of the initial value of the reflectance was 240 seconds, and the recording contrast was 0.18. 65
When left for 1000 hours at 85 ° C. and 85% RH, the reflectance became 32%.

[0031]

As described above, according to the production method of the present invention, the durability and the durability of the thin film-like organic layer coated with a solvent are improved.
Since a recording layer having good light resistance and reflectance is obtained, a highly reliable read-only optical recording medium which is prevented from being deteriorated by a reproduction laser can be provided.

When the track guide groove is formed by using a photocurable resin, the recording sensitivity is significantly reduced after the sealing and sealing, so that the already recorded information is not completely erased by mistake. In addition, since the solvent resistance is much better than that of PMMA or PC, there is an effect that the solvent can be selected at the time of coating the recording layer.

Also, since a reproduction stamper is not manufactured to produce an optical recording medium, it is possible to obtain a recording medium with a small quantity at a relatively low cost.

Claims (3)

(57) [Claims] 1. An optical recording method comprising: forming a recording layer made of an organic material on a substrate; performing writing on the recording layer using a laser; and maintaining the recording layer under heating and humidification conditions for 10 hours or more. The method of manufacturing the medium. 2. The method according to claim 1, wherein the optical recording medium is a card. 3. The method according to claim 1, wherein the substrate has a track guide groove made of a photocurable resin.