JPH10188371A - Optical recording medium and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate a fault whom a drying stage has and to dry in a short time by applying a liq. in which a dyestuff is dissolved or suspended in an org. solvent on a substrate, then irradiating the liq. with UV radiation and drying in a production stage of an optical recording medium. SOLUTION: In the optical recording medium, a recording layer containing the dyestuff, a metallic reflective layer and a protective layer consisting of a UV curing resin are laminated in order on a transparent substrate. The dyestuff having an absorption at an oscillation wave length region of a semiconductor laser such as polymethine based dyestuff and phthalocyanine is exemplified for example as the dyestuff used to the recording medium containing this dyestuff, and these dyestuffs are used by mixing one or >=2 kinds. At the time of forming the film of the dyestuff by a coating method, the dyestuff is applied by dissolving or suspending the dyestuff in a solvent substantially hardly dissolving the resin for the substrate. Some degree of the solvent is incorporated in the formed dyestuff-containing layer, and in order to dry the layer to an order hardly exerting bad influence to a recording characteristic, the layer is irradiated with the UV ray.

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 disadvantages of the conventional solvent drying step, and it is possible to dry the solvent in a shorter time. An object of the present invention is to provide a method for manufacturing an optical 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 the preparation of a recording layer in a short time. As a result, they found that drying by irradiating ultraviolet light instead of using hot air was an extremely effective means, and completed the present invention.

That is, the present invention provides (1) a method of manufacturing an optical recording medium comprising a recording layer containing a dye, a metal reflection 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 ultraviolet light and drying. Is a method for producing an optical recording medium according to the above (1), wherein is a phthalocyanine or naphthalocyanine dye, and (3) a method for preparing a dye-containing recording layer, a metal reflection layer, or a UV-curable resin on a transparent resin substrate. In an optical recording medium obtained by sequentially laminating protective layers, 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 ultraviolet light. Yes, and (4) Element is an optical recording medium according to (3) 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.

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 dye-containing layer formed is usually 0.5 to 10%
Contains a certain amount of solvent. The present invention is characterized by irradiating with ultraviolet light in order to dry it to such an extent that it does not adversely affect the recording characteristics, especially the jitter characteristics, that is, to 0.1% or less.

An ultraviolet light source needs to have an emission spectrum including an absorption wavelength range of a solvent, and a high-pressure mercury lamp, a metal halide lamp, a fluorescent UV
A lamp or the like is used. Light intensity is 0.1 to several tens mW / cm
^Two are common and are preferably used in the present invention. According to the present invention, this ultraviolet irradiation enables drying in a few minutes, and also makes it possible to easily obtain an optical recording medium having good recording characteristics.

When the dye used in the recording layer is a dye which is easily deteriorated by ultraviolet light, 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-tetrafluoroethylene was added to 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 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. 3000r more
The recording layer was formed by rotating at pm 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. When this was irradiated with a fluorescent UV lamp having a maximum emission wavelength of 351 nm and an intensity of ² mW / cm ² , the residual solvent amount decreased with the irradiation time as shown in FIG. Among those treated with ultraviolet light as described above, an irradiation time of 3 minutes was used, and a gold thin film having a thickness of 80 nm was formed thereon as a reflective layer by sputtering. After spin-coating Dicure-SD-17 (ultraviolet curable resin from Dainippon Ink and Chemicals, Inc.), it was cured by irradiating it with 2000 mj of ultraviolet light, and a 6 μm protective layer was formed to produce an optical recording medium. . This medium is a Philips CD-
Recorded by R writer CDD522
When the recording characteristics were evaluated using DU1000, the jitter value was 25 ns and the error rate was 5 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 3 minutes in the same manner as in Example 1. When the recording characteristics were measured in the same manner, the jitter value was 43 ns and the error rate was 65.
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 drying of the recording layer using ultraviolet light in the optical recording medium that can be additionally recorded on a mold, drying can be achieved in a very short time, and a good recording medium can be manufactured at low cost and with little stagnation. Become.

[Brief description of the drawings]

FIG. 1 is a graph plotting how the amount of residual solvent decreases when a recording layer is dried by irradiation with ultraviolet 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,
A method for producing an optical recording medium, comprising irradiating with ultraviolet 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 immersed liquid to the substrate and then drying the applied liquid by irradiation with ultraviolet light. 4. The optical recording medium according to claim 3, wherein the dye is a phthalocyanine or naphthalocyanine dye.