JPH10199033A - Optical recording medium and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to attain drying in a short period of time, to lessen stagnation and to enable a low-cost production, by applying a liquid prepd. by dissolving or suspending a dye into an org. solvent on substrates, then irradiating these substrates with far IR light, thereby drying the coatings. SOLUTION: A substrate, which allows the transmission of light for executing recording and reading out of signals, is preferably used for the transparent resin substrate. A substrate which has transmittance of the light of >=85% and has small optical anisotropy is more preferable. For example, a substrate formed by using a plastic resin, such as acrylic resin, polycarbonate resin, polyamide resin, polyvinyl chloride resin, and polyolefin resin is recommended. The far IR light sources like ceramic preheaters, which generates a large quantity of far IR light are effectively utilized. The drying is usually made possible in several minutes to some ten minutes according to this method; in addition, the optical recording media having good recording characteristics are more easily obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical recording medium, and more particularly to a single-plate high-reflection write-once optical recording medium capable of recording large-capacity information and having a dye as a recording layer, and a method of manufacturing the same.

[0002]

2. Description of the Related Art A single-plate recordable and commercially available compact disc (hereinafter abbreviated as CD) player in which a dye is used as a recording layer, a metal reflective layer is provided on the recording layer, and a protective layer is further provided thereon. Optical recording media compatible with CD-ROM players and CD-I players are, for example, Optic
al Data Storage 1989 Technical Digest Series Vol.
1 45 (1989), JP-A-2-132656 and JP-A-2-168446
Has been proposed.

[0003] This optical recording medium is typically manufactured through the following steps. That is, (1) production of a substrate by injection molding, (2) cooling of the substrate, (3) application of a recording layer by spin coating, etc., (4) solvent drying, (5) preparation of a metal layer by sputtering, etc., (6) This is a preparation of a protective layer represented by coating and curing of a UV curable resin. Among them, the solvent drying step is very important, and if the solvent is not sufficiently removed, the recording characteristics of the medium, particularly the jitter characteristics, are affected, and the recording becomes unstable.

Conventionally, a hot air drying method has been used for drying a solvent. However, since drying can be performed only to a temperature at which a substrate is not deformed, drying generally takes a relatively long time. Therefore, there is a disadvantage that a large-scale apparatus is required, and the cost of the apparatus including the clean room is increased. Furthermore, the residence of the medium in the manufacturing process becomes longer,
It also has the disadvantage that it takes time to deal with troubles.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned drawbacks of the conventional solvent drying process, and it is an object of the present invention to provide a light drying method which can dry in a shorter time. An object of the present invention is to provide a method for manufacturing a recording medium and an optical recording medium manufactured by the method.

[0006]

Means for Solving the Problems The present inventors have intensively studied and studied a method for drying an organic solvent remaining during preparation of a recording layer in a short time. As a result, they found that drying by irradiating far-infrared light instead of using hot air was an extremely effective means, and completed the present invention.

That is, the present invention relates to (1) a method for manufacturing an optical recording medium comprising a recording layer containing a dye, a metal reflective layer, and a protective layer made of a UV-curable resin, which are sequentially laminated on a transparent resin substrate. A method for producing an optical recording medium, comprising applying a liquid in which a dye is dissolved or suspended in an organic solvent to the substrate, and then irradiating with far-infrared light and drying,
(2) The method for producing an optical recording medium according to (1), wherein the dye is a phthalocyanine or naphthalocyanine dye, and (3) a recording layer containing the dye on a transparent resin substrate; Layer, a protective layer made of a UV curable resin is sequentially laminated on an optical recording medium, a liquid in which a dye is dissolved or suspended in an organic solvent is applied to the substrate, and then dried by irradiation with far-infrared light. (4) The optical recording medium according to (3), wherein the dye is a phthalocyanine or naphthalocyanine dye.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION As the transparent resin substrate used in the present invention, one that transmits light for recording and reading out signals is preferable. 85% light transmittance
Those having the above and having small optical anisotropy are desirable. For example, acrylic resin, polycarbonate resin,
A substrate using a thermoplastic resin such as a polyamide resin, a vinyl chloride resin, or a polyolefin resin is a preferred example. Among these, an acrylic resin, a polycarbonate resin, and an injection molded resin substrate of a polyolefin resin are preferable from the viewpoint of mechanical strength of the substrate, ease of providing a groove or a read-only signal, etc., and economical efficiency. A resin substrate is most preferred.

The shape of these substrates may be plate-like or film-like, circular or card-like. The surfaces of these substrates have grooves for controlling the recording position. In addition, a pit or the like for information or the like for partial reproduction only may be provided. It is preferable that such grooves and pits are provided when a substrate is formed by injection molding or casting.

In the optical recording medium according to the present invention, a recording layer containing a dye, a reflective layer, and a protective layer are sequentially laminated on the transparent resin substrate. Examples of the dye to be obtained include dyes having absorption in the oscillation wavelength region of a semiconductor laser, such as a polymethine dye, a phthalocyanine dye, a naphthalocyanine dye, a naphthoquinone dye, an azulene dye, and a dithiol metal complex dye. These dyes may be substituted with various substituents for solubility in a solvent or recording characteristics. These dyes can be used alone or in combination of two or more. Among these dyes, it is preferable to use a phthalocyanine dye or a naphthalocyanine dye in consideration of the durability of the dye.

In the present invention, the recording layer containing the dye described above can be generally formed by a coating method such as spin coating, spraying, or dipping.

When the above-mentioned dye is formed into a film by a coating method, the dye may be dissolved or suspended in a solvent which does not damage the resin substrate, that is, a solvent which does not substantially dissolve the resin for the substrate. Examples of such a solvent include alcohols and hydrocarbons, and specific examples include methanol, ethanol, isopropyl alcohol, ether, hexane, nonane, dimethylcyclohexane, octane, decane, methylcyclohexane, and ethylcyclohexane. These may be used as a mixture,
A small amount of a solvent that dissolves the substrate may be added for the purpose of improving the solubility of the dye and the like.

In the present invention, the thickness of the recording layer is usually 50
After forming the recording film, the outermost recording film may be removed with a solvent in order to improve the adhesion of the protective layer.

When forming a recording layer containing a dye, a resin such as nitrocellulose, ethyl cellulose, acrylic resin, polystyrene resin, urethane resin, etc., a leveling agent, an antifoaming agent, etc., in addition to the above-mentioned dye, are used in the present invention. They can be used together as long as the effect is not impaired.

The formed dye-containing layer usually contains about 0.5 to 10% of a solvent. The present invention is characterized by irradiating with far-infrared light in order to dry this to a degree that does not adversely affect the recording characteristics, particularly the jitter characteristics, that is, to 0.1% or less.

As the far-infrared light source, one that generates a large amount of far-infrared light, such as a ceramic plate heater, is effectively used. At that time, the medium surface temperature is 60 ~ 90 ℃
Need to be controlled. Normally, at temperatures exceeding 90 ° C, heat may deform the medium, and conversely,
If the temperature is lower than 60 ° C., a sufficient drying effect cannot be obtained. By this far-infrared irradiation, according to the present invention, drying can be usually performed in several minutes to several tens of minutes, and an optical recording medium having good recording characteristics can be more easily obtained.

When the dye used in the recording layer is a dye which is easily deteriorated by light and heat, such as a cyanine dye,
The method of the present invention is difficult to apply. In this respect, it is preferable in the present invention to use a light-fast dye such as a phthalocyanine or naphthalocyanine dye.

In the present invention, the reflective layer provided on the recording layer is usually preferably a metal thin film. In the present invention, in consideration of compatibility with a normal CD player, it is preferable that the reflectance of the medium on the groove be 60% or more.
Preferred metals include aluminum, gold, silver, copper, platinum, nickel, and alloys containing these metals as one component. The reflective layer of these metals can be formed by a method such as vapor deposition or sputtering. The thickness of these reflective layers is usually preferably about 500 to 2000 mm. Of course, it is preferable that the reflective layer is formed beyond the groove.

A resin is usually used as the protective layer. From the viewpoint of the protective effect, a thermosetting resin, particularly an ultraviolet curable resin is preferable from the viewpoint of productivity and the like. The thickness of the protective layer is preferably about 1 to 15 μm. It is preferable that the protective layer is formed over the recording layer and the reflective layer. Examples of the method for forming the protective layer include spin coating, screen printing, immersion, and spraying.

In the optical recording medium of the present invention, a protective layer may be laminated on the protective layer for the purpose of improving durability, or a printable layer corresponding to an ink jet printer may be laminated. In addition, printing of a label or the like can be performed.

[0021]

EXAMPLES Hereinafter, the optical recording medium of the present invention and the method for producing the same will be described in detail with reference to Examples and Comparative Examples, but the present invention is not limited thereto.

Example 1 Pd-tetra is formed at the center of the grooved surface of an injection molded polycarbonate resin substrate having a spiral groove (depth 140 nm, width 0.5 μm, pitch 1.6 μm) having a thickness of 1.2 mm and a diameter of 120 mm. -Brominated (t-butylcyclohexyloxy) phthalocyanine bromide (average of 3.0 / molecule) Dye A 3.5 wt% octane solution was dropped, and the resin substrate was rotated at a speed of 1500 rpm for 10 seconds. Another 3000
The recording layer was formed by rotating at 20 rpm for 20 seconds. The amount of the residual solvent in the recording layer was measured by head space gas chromatography and found to be 7.8% with respect to the dye. In order to remove the solvent of this recording layer by drying, the emission surface dimension is 400 mm ×
When a ceramic plate heater manufactured by Noritake Co., Ltd. having a power capacity of 1 kW and having a capacity of 300 mm was placed at a position 100 mm away from the medium and irradiated, the amount of residual solvent decreased with the irradiation time as shown in FIG. Among those treated with far-infrared light as described above, one having an irradiation time of 10 minutes was used, and a gold thin film having a thickness of 80 nm was formed thereon as a reflective layer by sputtering. On top, Dicure-SD-17
(Ultraviolet curable resin from Dainippon Ink and Chemicals, Inc.) was spin-coated, cured by irradiating with 2000 mj of ultraviolet light, and a 6 μm protective layer was formed to produce an optical recording medium.
This medium was converted to a Philips CD-R writer CDD.
Recording was performed at 522, and the recording characteristics were evaluated using DDU1000 manufactured by Pulstec.
s, the error rate was 2 cps, which was very good.

Comparative Example 1 The same operation as in Example 1 was performed except that the recording layer was dried with a hot air dryer at 70 ° C. As shown in FIG. 2, the results show that according to this example, in order to reduce the amount of residual solvent to 0.1% or less,
It turns out that it takes as long as 120 minutes. A medium was prepared from those treated as described above and dried for 10 minutes in the same manner as in Example 1, and the recording characteristics were measured in the same manner. A jitter value of 43 ns and an error rate of 65 were obtained.
The value was as high as cps.

[0024]

As is clear from the results of the above Examples and Comparative Examples, according to the present invention, a single plate in which a recording layer containing a dye, a reflective layer, and a protective layer are sequentially laminated on a resin substrate. By performing the recording layer drying using far-infrared light on an optical recording medium that can be additionally recorded on a mold, the drying can be achieved in a very short time, and a good recording medium can be manufactured at low cost and with little stagnation. It becomes possible.

[Brief description of the drawings]

FIG. 1 is a graph plotting how a residual solvent amount is reduced when a recording layer is dried by irradiation with far-infrared light in Example 1.

FIG. 2 is a graph plotting how the amount of residual solvent decreases when the recording layer is dried using hot air at 70 ° C. in Comparative Example 1.

Claims (4)

[Claims] In a method for manufacturing an optical recording medium, a recording layer containing a dye, a metal reflective layer, and a protective layer made of a UV-curable resin are sequentially laminated on a transparent resin substrate, wherein the dye is dissolved in an organic solvent. Or after applying the suspended liquid to the substrate,
Next, a method of manufacturing an optical recording medium, which comprises irradiating with far-infrared light and drying. 2. The method according to claim 1, wherein the dye is a phthalocyanine or naphthalocyanine dye. 3. An optical recording medium in which a recording layer containing a dye, a metal reflective layer, and a protective layer made of a UV curable resin are sequentially laminated on a transparent resin substrate, wherein the dye is dissolved or suspended in an organic solvent. An optical recording medium manufactured by applying the liquid thus obtained to the substrate and then drying the applied liquid by irradiation with far-infrared light. 4. The optical recording medium according to claim 3, wherein the dye is a phthalocyanine or naphthalocyanine dye.