JP2001006209A - Optical recording medium and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical recording medium excellent in environmental resistance, and a method for manufacturing the optical recording medium. SOLUTION: This optical recording medium has an organic dye film, a light reflecting film and a protective film on a light transmissible substrate in this order and the organic dye film contains a 2-15 wt.% organic solvent to the organic dye. A solution of the organic dye dissolved in the organic solvent is applied to the light transmissible substrate by a spin-coating method to form the organic dye film, subsequently, the light reflecting film is formed on the organic dye film without drying treatment of the residual organic solvent in the organic dye film and the protective film is formed on the light reflecting film to manufacture the optical recording medium containing the 2-15 wt.% organic solvent to the organic dye in the organic dye film.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for manufacturing an optical recording medium having an organic dye film and an optical recording medium.

[0002]

2. Description of the Related Art Conventionally, a recording film of a so-called writable write-once type optical recording medium includes, for example, cyanine-based, phthalocyanine-based, and the like as represented by CD-R and DVD-R.
It is well known that organic dyes such as azo dyes are used.

In the formation of a recording film mainly composed of an organic dye, such an organic dye is generally used, for example, cyclohexane, cyclohexanone, methanol, ethanol, isopropyl alcohol, diacetone alcohol, methyl cellosolve, ethyl cellosolve, butyl acetate, fluorinated An organic solvent such as alcohol is used alone or as a mixture, and is applied onto a substrate by spin coating. A reflection film is formed on the formed recording film.

By the way, the optical recording medium is required to have excellent environmental resistance in consideration of various use environments, and it is preferable that the amount of the solvent contained in the recording film is small in order to improve the environmental resistance. It is preferred. Therefore, the organic dye was dissolved in an appropriate solvent, and an organic dye film was formed by a spin coating method, and then the residual solvent in the organic dye film was removed by an appropriate drying process such as high-temperature drying, vacuum drying, and air drying. Thereafter, a method of forming a reflective layer thereon is usually used.

[0005] For example, Japanese Patent Publication No. 7-96333 discloses that a coating solution is prepared by dissolving a dye in a solvent containing fluorinated alcohol, and then the coating solution is applied on a substrate and dried to form a recording layer. Is disclosed.

For example, Japanese Patent Application Laid-Open No. 4-369577 discloses that after a recording film is formed, a reflective film is formed so that the amount of a solvent contained in the applied recording film is 10% by weight or less based on the recording film. It is disclosed that the amount of a solvent in a recording film is reduced by intentionally performing drying.

[0007]

However, the drying step after the formation of the recording film has a drawback that it requires a long time for sufficient removal of the solvent, which is not preferable in manufacturing. It is difficult to increase the drying temperature in order to avoid long-term drying in consideration of the effect on the applied organic dye, the effect on the resin used for the substrate, the effect on the mechanical accuracy of the substrate, and the like. Also, in JP-A-4-369577,
Although the amount of solvent in the recording film at the time of forming the reflective film is considered,
The amount of solvent in the recording film in the obtained optical recording medium is not considered at all.

An object of the present invention is to provide an optical recording medium having excellent environmental resistance. Further, the object of the present invention is to
It is an object of the present invention to provide a method for efficiently manufacturing an optical recording medium having excellent environmental resistance.

[0009]

Means for Solving the Problems The inventors of the present invention have conducted various studies to improve the above-mentioned problems, and as a result, even if drying after forming an organic dye film by a spin coating method is not carried out, environmental resistance is high. It has been found that an optical recording medium excellent in quality can be manufactured. It was also found that a specific solvent remained in the organic dye film of the optical recording medium thus obtained in a state of being included in the dye film.

Further studies have revealed that in order to obtain excellent environmental resistance, it is important to define the type of the solvent and the relative weight of the solvent relative to the weight of the dye in the dye film. That is, it contains a fluorinated alcohol having a boiling point of 60 ° C. or higher (eg, 2,2,3,3-tetrafluoro-1-propanol), or an organic solvent used at the time of applying a dye such as diacetone alcohol or 2-ethoxyethanol. The optical recording medium having an organic dye film having a ratio of 2 to 15% by weight, preferably 2.2 to 14.5% by weight, based on the weight of the organic dye has excellent environmental resistance.

According to the present invention, an organic dye film is formed by applying a solution obtained by dissolving an organic dye in an organic solvent on a light-transmitting substrate by a spin coating method, and then forming an organic solvent remaining in the organic dye film. Forming a light-reflective film on the organic dye film without performing a drying treatment, and further forming a protective film on the light-reflective film, wherein the organic dye film contains 2 to 15% by weight of the organic dye.
This is a method for producing an optical recording medium containing the above organic solvent. In the above method, in forming the organic dye film, spin coating is preferably performed at a rotation speed of 3500 rpm or more.

The present invention provides an organic dye film on a light-transmitting substrate,
An optical recording medium having a light reflective film and a protective film in this order, wherein the organic dye film contains 2 to 15% by weight of an organic solvent with respect to the organic dye. In the optical recording medium of the present invention, it is preferable that the organic solvent is at least one selected from a fluorinated alcohol having a boiling point of 60 ° C. or higher, 2-ethoxyethanol, and diacetone alcohol. Further, the organic solvent is mainly 2,2,3,3-
Preferably, it is tetrafluoro-1-propanol.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The structure of an optical recording medium according to the present invention is basically the same as that of a conventional write-once optical recording medium, and is recorded by a laser beam on a light-transmitting substrate on which a pregroove is formed. An organic dye recording film for performing reproduction is provided, a reflection film for obtaining light reflectance is provided on the organic dye recording film, and a protection for protecting the organic dye recording film and the reflection film on the reflection film is further provided. A film is provided.

The present invention also includes an optical recording medium obtained by bonding the optical recording medium having such a layer structure to at least one of the optical recording media via an adhesive layer. Alternatively, the present invention includes an optical recording medium in which the adhesive layer also functions as a protective film on the reflective film. In order to enhance the scratch resistance of the light-transmitting substrate, an organic protective layer may be provided on the surface of the substrate opposite to the organic dye film.

Examples of the material of the light-transmitting substrate include a polymer material represented by a polycarbonate resin, an acrylic resin, a polystyrene resin, an epoxy resin, a polyester resin, a vinyl chloride resin, an olefin resin, and an inorganic material such as glass. Can be used. When a resin material is used, a substrate is obtained by transferring a pre-groove of a matrix mainly by injection molding, and when using glass, mainly by a 2P method.

An organic dye film containing an organic dye as a main component is formed on a substrate. The organic dye recording film should be capable of reading a change in shape and a change in optical characteristics of the recording film formed by physical and / or chemical change by absorbing a recording laser beam by a reproduction laser beam. I just need.
To form a locally modified portion, a phthalocyanine dye having an absorption band in a semiconductor laser wavelength band, a cyanine dye,
Azo dyes and the like are often used. These dyes may be used alone or in combination of two or more.
If necessary, a singlet oxygen quencher, an ultraviolet absorber and the like can be added. It is also preferable to use an ionic conjugate of a dye cation and a singlet oxygen quencher anion as the organic dye.

In the present invention, a coating solution in which an organic dye is dissolved in an organic solvent is prepared, and the coating solution is applied on a substrate by spin coating to form an organic dye film. It is desirable to adjust the concentration of the organic dye component in the coating solution, the thickness of the organic dye film to be formed, and the like so that a sufficient reflectance can be obtained after the formation of the reflective film.

As the organic solvent used for preparing the coating solution,
The fluorinated alcohol having a boiling point of 60 ° C. or more, particularly 2, 2, 3,
3-Tetrafluoro-1-propanol, 2-ethoxyethanol and diacetone alcohol are preferred. These solvents may be used alone or in combination of two or more. Fluorinated alcohols having a boiling point of less than 60 ° C. are sufficiently dried under the general high-temperature and high-humidity conditions of the conventional organic dye application step, but the organic dye cannot be uniformly applied due to a high drying rate.

Further, other solvents other than those mentioned above can be mixed and used as required. However, when selecting another solvent to be mixed, it is necessary not only to dissolve the organic dye but also to select a solvent that does not damage the light transmitting substrate to be used.

The number of revolutions of the spin coat is 3500 rpm
As described above, the rotation speed is preferably, for example, 3500 rpm to 5000 rpm, more preferably 4000 rpm to 5000 rpm, for example, more preferably 4500 rpm to 5000 rpm. With such high-speed rotation, the solvent can be efficiently removed. This rotation speed is the final rotation speed of the spin coating. For example, in spin coating, the initial rotation speed when the coating solution is dropped on the substrate may be set to about 300 rpm to 500 rpm, and the rotation speed may be gradually increased to finally make the rotation speed 3500 rpm or more.

After the spin coating, an organic solvent remains in the formed organic dye film, but a light reflecting film is formed on the organic dye film by a sputtering method without performing a drying treatment. The light reflection film is formed directly on the organic dye film, and the thickness of the reflection film is, for example, about 10 to 500 nm. The reflective film is made of a metal component including a single metal or another metal, and includes Au,
Elemental components such as Ag, Al, Cu, Cr, Ni, Si, and Ge are used alone or in a state containing other elements, and are formed by a sputtering method. In the sputtering step, the residual organic solvent in the organic dye film is considerably removed. conventionally,
After application of the organic dye film, high-temperature drying, vacuum drying, blast drying and the like have been performed, but this is not necessary in the present invention. By eliminating the drying step, the manufacturing time can be greatly reduced.

A protective film having a thickness of, for example, about 1 to 50 μm is provided on the reflective film. The protective film only needs to be able to protect the organic dye recording film and the reflective film, and the constituent material of the protective film is not particularly limited. As a material of the protective film, an ultraviolet curable acrylic resin is generally used because the protective film can be easily formed. The material of the protective film may be an organic material such as a vinyl chloride resin, an epoxy resin, or a polyester resin, or an inorganic material such as SiO ₂ or AlN. These materials may be used alone or as a mixture. In addition, different materials may be used in layers by using the protective film as a multilayer film.

A label printing layer may be further provided on the protective film. Alternatively, in the case where such an optical recording medium is attached with an adhesive layer provided on the side opposite to the light incident surface, the adhesive layer may also serve as a protective film. The protective film is preferably formed by a spin coating method in order to avoid damage to the reflective film, but may be formed by a screen printing method, a dipping method, a spray coating method, or the like.

The optical recording medium of the present invention has an organic dye film containing 2 to 15% by weight of an organic solvent with respect to the organic dye in the organic dye film. If the organic solvent content in this range,
The environmental resistance of the optical recording medium is practically sufficient. When the content of the organic solvent increases, the environmental resistance tends to deteriorate. When the content of the organic solvent exceeds 15% by weight, a problem occurs in the environmental resistance of the optical recording medium. On the other hand, the organic solvent content is 2% by weight.
In order to produce a medium having a size smaller than the above, long-time high-temperature drying is required, which is disadvantageous in the production process. Alternatively, when a short period of severe drying is performed, an adverse effect occurs on the organic dye and the substrate.
The organic solvent content in the organic dye film is 2.
The environment resistance of the optical recording medium having the organic dye film of 2 to 14.5% by weight is more excellent. In consideration of production efficiency, a more preferable organic solvent content is, for example, 2.3 to 1
0% by weight, and a more preferable organic solvent content is, for example, 2.5 to 5% by weight.

[0025]

EXAMPLES The present invention will be described below in more detail with reference to examples, but embodiments of the present invention are not limited thereto.

Example 1 As organic dyes, 6: 4 of cyanine dye NK3721 (manufactured by Hayashibara Biochemical Laboratory) and cyanine dye OM-57 (manufactured by Fuji Photo Film Co., Ltd.)
(Weight) A mixed dye was used. 2 g of the above cyanine mixed dye
Was dissolved in 100 g of 2,2,3,3-tetrafluoro-1-propanol (TFP) to prepare a coating solution. The coating solution was applied onto a polycarbonate injection molded substrate having a pregroove having a diameter of 120 mm and a thickness of 1.2 mm by a spin coating method. In the spin coating, when the coating solution is dropped on the substrate, the number of rotations is set to 300 rpm, and the number of rotations is gradually increased to finally reach 5,000 rpm.
m. Immediately after application, without drying, an Ag film having a thickness of 100 nm was formed on the dye film by a sputtering method. Further, a UV-curable acrylic resin, Die Cure Clear SD318 (manufactured by Dainippon Ink and Chemicals, Inc.) is applied on the Ag film by a spin coating method to form a protective film having a thickness of 5 μm. Produced. The thickness of the organic dye film was about 250 nm in the groove part and about 150 nm in the land part. The adhesion between the organic dye film and the reflective film was also good.

Using a commercially available CD-R drive, recording was performed on 10 of the 100 obtained optical recording media, and a weathering test was performed for 200 hours in a constant temperature and humidity chamber at a temperature of 80 ° C. and a humidity of 80%. Was. The characteristics (jitter value) before and after the weathering test,
Audio Development CD-CATS-S
As a result of measurement and evaluation using A3, any medium has the same initial (before weathering test) characteristics as conventional CD-R,
This property did not deteriorate even after the weathering test. Table 1 shows the jitter values before and after the weather test. In Table 1, the jitter value is an average value of 10 measurement sheets, and the measurement position is a radial position from the center of the medium.

With respect to 90 of the 100 optical recording media obtained, the organic dye film in the medium was washed away with ethanol, and the obtained liquid was dried at room temperature. When the amount of the residual solvent in the obtained dye was measured by gas chromatography, 4.69% by weight of the residual solvent was detected based on the weight of the dye in the optical recording medium. It was 2,2,3,3-tetrafluoro-1-propanol. Ethanol was below the detection limit.

Example 2 100 optical recording media were produced in the same manner as in Example 1 except that a coating solution prepared by dissolving 2 g of the same cyanine dye as in Example 1 in 100 g of diacetone alcohol was used. . When the characteristics of the optical recording medium were measured and evaluated in the same manner as in Example 1, the initial characteristics of all the media were equivalent to those of the conventional CD-R, and these characteristics did not deteriorate even after the weather resistance test. When the amount of the residual solvent with respect to the weight of the dye in the optical recording medium was measured in the same manner as in Example 1,
2.9% by weight of diacetone alcohol was detected. Ethanol was below the detection limit.

Example 3 100 optical recording media were produced in the same manner as in Example 1 except that a coating solution prepared by dissolving 2 g of the same cyanine dye as in Example 1 in 100 g of 2-ethoxyethanol was used. did. When the characteristics of the optical recording medium were measured and evaluated in the same manner as in Example 1, the initial characteristics of all the media were equivalent to those of the conventional CD-R, and these characteristics did not deteriorate even after the weather resistance test. When the amount of the residual solvent with respect to the weight of the dye in the optical recording medium was measured in the same manner as in Example 1,
2.3% by weight of 2-ethoxyethanol was detected.
Ethanol was below the detection limit.

COMPARATIVE EXAMPLE 1 Using the same coating solution as in Example 1, when the coating solution was dropped on the substrate, the number of rotations was 300.
rpm, gradually increase the number of revolutions, and finally 30
Spin coating was performed at 00 rpm. Otherwise, in the same manner as in Example 1, 100 optical recording media were produced. When the characteristics of the optical recording medium were measured and evaluated in the same manner as in Example 1, the initial characteristics were poor as compared with the conventional CD-R, and the characteristics were further deteriorated after the weather resistance test. When the amount of the residual solvent with respect to the weight of the dye in the optical recording medium was measured in the same manner as in Example 1, 16% by weight of the residual solvent was detected, and these were fluorinated alcohols, and were mainly 2,2,3,3-tetrafluoroethylene. It was fluoro-1-propanol. Ethanol was below the detection limit.

Comparative Example 2 Using the same coating solution as in Example 2, when the coating solution was dropped on the substrate, the number of rotations was 300.
rpm, gradually increase the number of revolutions, and finally 30
Spin coating was performed at 00 rpm. Otherwise, in the same manner as in Example 2, 100 optical recording media were manufactured. When the characteristics of the optical recording medium were measured and evaluated in the same manner as in Example 1, the initial characteristics were poor as compared with the conventional CD-R, and the characteristics were further deteriorated after the weather resistance test. When the amount of the residual solvent with respect to the weight of the dye in the optical recording medium was measured in the same manner as in Example 1, 17% by weight of diacetone alcohol was detected. Ethanol was below the detection limit.

Comparative Example 3 Using the same coating solution as in Example 3, when the coating solution was dropped onto the substrate, the number of rotations was 300.
rpm, gradually increase the number of revolutions, and finally 30
Spin coating was performed at 00 rpm. Otherwise, in the same manner as in Example 3, 100 optical recording media were produced. When the characteristics of the optical recording medium were measured and evaluated in the same manner as in Example 1, the initial characteristics were poor as compared with the conventional CD-R, and the characteristics were further deteriorated after the weather resistance test. When the amount of the residual solvent relative to the weight of the dye in the optical recording medium was measured in the same manner as in Example 1, 16% by weight of 2-ethoxyethanol was detected. Ethanol was below the detection limit.

Comparative Example 4 The same coating solution as in Example 1 was used.
120mm diameter, 1.2mm thickness with pre-groove
Was applied by a spin coating method on an injection molded substrate made of polycarbonate. In the spin coating, when the coating solution was dropped onto the substrate, the number of revolutions was set to 300 rpm, and the number of revolutions was gradually increased to finally 1,200 rpm.
After the application, the coating was dried in a thermostat at 60 ° C. for 12 hours. After drying, an Ag film having a thickness of 100 nm was formed on the dye film by a sputtering method. Further, Die Cure Clear SD318 is applied on the Ag film by a spin coating method, and has a thickness of 5 μm.
Was formed, and 100 optical recording media were manufactured.
The thickness of the organic dye film was about 250 nm in the groove part and about 150 nm in the land part.

When the characteristics of the optical recording medium were measured and evaluated in the same manner as in Example 1, the initial characteristics of each medium were equivalent to those of the conventional CD-R, and the characteristics did not deteriorate even after the weathering test. When the amount of the residual solvent relative to the weight of the dye in the optical recording medium was measured in the same manner as in Example 1, it was less than 2% by weight. Ethanol was below the detection limit. However, the preparation of this medium requires a drying time of as much as 12 hours as described above, so that the time load is considerably large as compared with the present invention.

[0036]

[Table 1]

The present invention may be embodied in various other forms without departing from its spirit or essential characteristics. Therefore, the above-described embodiment is merely an example in every aspect, and should not be construed as limiting. Furthermore, all modifications belonging to the equivalent scope of the claims are within the scope of the present invention.

As described above, according to the present invention, an optical recording medium having excellent electrical characteristics and reliability can be obtained by including an organic solvent in an organic dye film in an amount of 2 to 15% by weight based on the organic dye. Obtainable. Further, according to the production method of the present invention, such an optical recording medium can be obtained, and there is no need to perform a drying step after the application of the organic dye film, thereby simplifying the production steps and greatly reducing the production time. The effect is also obtained.

Claims (5)

[Claims] 1. An organic dye film is formed by applying a solution in which an organic dye is dissolved in an organic solvent on a light-transmitting substrate by a spin coating method, and then drying the organic solvent remaining in the organic dye film. Forming a light-reflective film on the organic dye film without performing a treatment, and further forming a protective film on the light-reflective film; A method for producing an optical recording medium containing: 2. The method according to claim 1, wherein the number of rotations is 35 in forming the organic dye film.
The method for producing an optical recording medium according to claim 1, wherein the spin coating is performed at 00 rpm or more. 3. An optical recording medium having an organic dye film, a light reflecting film and a protective film on a light-transmitting substrate in this order, wherein the organic dye film contains 2 to 15% by weight of organic dye based on the organic dye. An optical recording medium containing a solvent. 4. The optical recording medium according to claim 3, wherein the organic solvent is at least one selected from a fluorinated alcohol having a boiling point of 60 ° C. or higher, 2-ethoxyethanol, and diacetone alcohol. 5. The optical recording medium according to claim 3, wherein the organic solvent is mainly 2,2,3,3-tetrafluoro-1-propanol.