JP2000285518A - Optical recording medium and manufacturing method thereof - Google Patents

Abstract

(57) Abstract: When Ag or a metal containing Ag is used for a metal reflection layer, it is possible to prevent or reduce the occurrence of defects occurring in the reflection layer, prevent or reduce the destruction and deterioration of recorded information, and improve light resistance. Provided is an optical recording medium having good reliability and improved reliability, and a method for manufacturing the same. SOLUTION: The thickness of a metal reflective layer containing Ag formed by sputtering is set to 100 n in a recordable / reproducible region.
m, and a method for producing an optical recording medium in which a gas containing Ar as a main component is used as a sputtering gas when forming a metal reflective layer, and the flow rate of the gas is 30 sccm or more.

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 a method for manufacturing the same, and more particularly, to an optical recording medium (for example, CD-R, DVD-R) and a method of manufacturing the same.

[0002]

2. Description of the Related Art In an optical recording medium using an organic dye as a recording layer, such as a CD-R or a DVD-R, a reflection layer provided on the recording layer has hitherto been mainly used in view of reflectance and chemical stability. In recent years, Au has been used, but in recent years, for the purpose of further improving the characteristics and reducing the material cost,
Ag or a metal containing Ag, which has a higher reflectivity and is less expensive than Au, has been used. However, Ag has a lower chemical stability than Au, so that a combination of long-time light irradiation and a dye material in the lower layer causes a minute defect in the metal reflective film to destroy recorded information. As a result, the reliability as a recording medium is significantly reduced.
In addition, the occurrence of the above-mentioned defects naturally deteriorates the light resistance.

Incidentally, in an optical recording medium using a metal reflective layer made of Ag or a metal containing Ag, for example, JP-A-6-325408, JP-A-7-14221, JP-A-7-105572, etc. However, none of them mention requirements for ensuring light fastness. This is probably because the light resistance of the optical recording medium has been improved by improving the light resistance of the recording layer itself.

[0004]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to prevent or reduce the occurrence of defects in a reflective layer when Ag or an Ag-containing metal is used for the metal reflective layer. It is an object of the present invention to provide an optical recording medium having good light resistance and improved reliability by preventing or reducing deterioration, and a method for manufacturing the same.

[0005]

In order to prevent or reduce the generation of minute defects in the metal reflecting layer containing Ag as described above, the present inventors have made various material changes and layer structure changes. Since the above defects occur in the metal reflective layer made of Ag, it is necessary to define the structural parameters of the metal reflective layer in order to improve the light resistance. As a result of repeated studies, the thickness of the metal reflective layer containing Ag formed by sputtering was recorded and recorded.
It was found that an optical recording medium having good light resistance and reliability can be obtained by defining the area in a reproducible area.
It has been found that an optical recording medium with good light resistance and reliability can be manufactured by defining the sputter gas and the flow rate thereof at the time of forming the metal reflection layer containing, and the present invention has been completed.

That is, according to the present invention, first, Ag is formed on at least a transparent substrate via a recording layer containing any of a cyanine-based, phthalocyanine-based, and azo-based organic dye.
Alternatively, an optically structured structure having a metal reflective layer containing Ag, and further having a lower protective layer of at least 2 μm in thickness made of an ultraviolet curable resin on the reflective layer and an upper protective layer containing an ultraviolet curable resin thereon. In an optical recording medium for recording / reproducing or erasing information, a metal reflective layer is formed by sputtering, and the minimum thickness of a recordable / reproducible region is 100 nm.
An optical recording medium characterized by the above is provided.
Secondly, there is provided the optical recording medium according to the first aspect, wherein the minimum thickness of the metal reflective layer in the recordable / reproducible region of the recording medium is 200 nm or less. Third, the optical recording medium according to the first or second aspect, wherein the in-plane variation of the recordable / reproducible region of the film thickness of the metal reflective layer is 50% or less. Provided. Fourthly, there is provided an optical recording medium according to the first, second or third aspect, wherein a sputter output at the time of forming a metal reflective layer is 4 kW or less. Is done.

According to the present invention, fifthly, a recording layer containing an organic dye is provided on at least the transparent substrate, and a metal reflection layer containing 80 to 100 atomic% of silver is provided on the recording layer. Further, in a method for manufacturing an optical recording medium for optically recording / reproducing or erasing information having a structure having a protective layer made of an ultraviolet curable resin on the reflective layer, a metal reflective layer is formed by sputtering, and Ar as sputtering gas
The method for producing an optical recording medium is characterized in that a gas containing as a main component is used and the gas flow rate of the sputtering gas is 30 sccm or more. Sixthly, there is provided the method for manufacturing an optical recording medium according to the fifth aspect, wherein the gas flow rate of the sputtering gas is 100 sccm or less. Seventhly, there is provided the method for manufacturing an optical recording medium according to the fifth or sixth aspect, wherein the metal reflective layer contains 99 to 100 atomic% of silver. Eighthly, there is provided the method for manufacturing an optical recording medium according to the fifth, sixth or seventh aspect, further comprising a step of bonding the protective layer side to another substrate.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described more specifically. The optical recording medium of the present invention is a CD-ROM.
This is a write-once optical recording medium using a material containing an organic dye for a recording layer, such as R and DVD-R. As shown in FIG. 1, for example, the layer structure has a recording layer 2 made of an organic dye on a transparent substrate 1 made of a resin or glass, a metal reflective layer 3 thereon, and It has one or more protective layers 4 (and optionally 5) made of resin or containing resin as a main component. The optical recording medium of the present invention defines the structure of the recording layer, the reflective layer, and the protective layer, and there is no limitation on other layer structures such as a transparent substrate.

The transparent substrate preferably has a transmittance of 85% or more with respect to recording light and reproduction light, and is formed of a substantially transparent resin or glass. The recording light and the reproduction light are emitted from below the transparent substrate.

The recording layer contains an organic dye such as a phthalocyanine dye, a cyanine dye or an azo dye as a material. The recording layer may contain a quencher or other additives as necessary. The recording layer may be formed by, for example, dissolving a dye in a solvent, applying the solution by spin coating, or the like, and then drying. The film thickness is 5
It is preferably from 0 to 300 nm.

The metal reflecting layer is made of Ag or a metal containing Ag. That is, it is formed by sputtering Ag or a metal containing Ag, and is preferably a layer containing 80 to 100 atomic% of Ag. Ar gas is used as a sputtering gas.
Is formed by DC magnetron sputtering using a gas mainly composed of Ar gas is a main component, for example, 90%
If it is above, other gas may be mixed. When a metal reflective layer containing a metal other than Ag is formed, an alloy target may be used, or Ag and a metal other than Ag may be used as separate targets.

The thickness of the metal reflection layer must have a minimum value within a recordable area on an optical recording medium of 100 nm or more in order to maintain high light resistance and obtain high modulation characteristics. And it is preferably 200 nm or less. Further, in order to maintain the uniformity of the characteristics in the plane, it is preferable that the fluctuation of the thickness of the reflective layer in the recordable / reproducible region is within 50% of the average value. Further, the sputter output is preferably set to 4 kW or less in order to maintain high recording characteristics.

[0013] One or more protective layers are formed on the metal reflective layer. The lower protective layer is spin-coated with UV curable resin,
Thereafter, it is created by irradiating ultraviolet rays and curing. The minimum thickness of the lower protective layer in the recordable area is 2μ.
m or more. As the lower protective layer material, ultraviolet curable resins SD1700 and SD3 manufactured by Dainippon Ink and Chemicals, Inc.
18 and the like.

An upper protective layer or the like may be formed on the protective layer by screen printing or the like, or label information may be printed. The upper protective layer is, for example,
A fine particle filler of an inorganic oxide such as silicon dioxide or titanium oxide may be contained. By containing 1 to 30% by weight of the inorganic oxide fine particle filler, good writability and hardness for protecting the lower reflective layer / recording layer can be obtained when writing with an oil-based pen or the like. The upper protective layer is formed by a coating method. Specifically, an upper protective layer is formed by applying a dye containing a fine particle filler of inorganic oxide and a coloring agent to the surface of the lower protective layer. In order to increase the strength of the upper protective layer, it is preferable that the coating liquid contains an ultraviolet-curable resin such as an acrylic or epoxy resin, and is cured by ultraviolet rays or the like after the application. In addition, you may add a photoreactive monomer etc. to a coating liquid as needed for viscosity adjustment. The coating method is not particularly limited, but screen printing is desirable in terms of thickness control and process tact. Further, instead of a single plate, a configuration may be adopted in which a medium or a dummy substrate having a similar configuration is bonded, such as a DVD-R.

The light fastness referred to in the present invention means that when the recording layer is irradiated with direct sunlight from the substrate side to the optical recording medium outdoors.
It refers to how long irradiation time can be read from recorded data. As a method of confirming light resistance, a device using a xenon lamp as a light source and having a spectral distribution similar to that of direct sunlight by a filter is used. The test equipment includes, for example, S
There are USTEST and Atlas Weather Meter.

In the present invention, by changing the pressure of the sputtering gas containing Ar gas as a main component, it is considered that the film quality of the sputtered metal reflective film changes, thereby improving the light resistance. The light resistance is gradually improved as the Ar gas pressure is increased. However, when the gas pressure exceeds 30 sccm, stable light resistance characteristics are obtained. The non-uniformity of the film thickness distribution at this time is 35.
%. Further, when the gas pressure is further increased, the film thickness distribution of the metal reflection film gradually becomes uneven, and the gas pressure becomes 1
If it exceeds 00 sccm, the non-uniformity becomes 65% or more, which affects the signal characteristics such as the modulation factor and the reflectance. A
In the metal reflection layer containing g as a main component, the reflectance is Ag
When the content is 100%, it is the highest, and if there is no problem in the temperature / humidity storage property, so-called weather resistance, it is desirable to increase the Ag content as much as possible.

In the present invention, there is no particular limitation on the structure from below the protective layer to the substrate, such as between the substrate and the recording layer, between the recording layer and the reflective layer, between the reflective layer and the protective layer, and the like. May be provided with an intermediate layer.

[0018]

EXAMPLES The present invention will be described more specifically with reference to the following examples. However, the technical scope of the present invention is not limited by the embodiment.

Example 1 A phthalonine dye was applied onto a polycarbonate CD-R substrate on which continuous grooves having a pitch of 1.6 μm were transferred, and dried to form an organic dye recording layer. The thickness of the recording layer was 200 nm in the smooth region of the substrate. An Ag film was formed on this recording layer by a sputtering method using argon ions, and was used as a metal reflection layer. Table 1 shows the results of X-ray measurement of the thickness at the thinnest point in the recordable / reproducible region of the sputtered film. An ultraviolet curable resin SD1700 manufactured by Dainippon Ink and Chemicals, Inc. was applied to the obtained sample, and irradiated with ultraviolet light to form a protective layer. Further, an ink hard coat clear manufactured by Jujo Kako Co., Ltd. was mesh-printed on the protective layer and irradiated with ultraviolet light to form an upper protective layer. Each of the obtained samples had characteristics equivalent to those of a general CD-R and was a medium satisfying the CD standard.

[0020]

[Table 1]

<Light Resistance Test> A light resistance test was performed using the sample prepared above. Yamaha CD-R drive,
The entire surface was written using CDE100, and BLER was measured using a measuring device CD-CATS SA3 manufactured by Audio Development. The writing of the CD-R is performed at 4 × speed. Thereafter, a light resistance test was performed, and changes in BLER before and after the test were observed. The conditions of the light resistance test are as follows. Light source: Xenon lamp, Radiation intensity: 0.35 W / m ² (420 nm), Temperature: 35 ° C., Humidity: 50% RH, Black body temperature: 63 ° C. Irradiation time: Approx. 300 hours Radiation intensity is in Miami, Florida It corresponds to the effective average radiation intensity of sunlight in fine weather.

B after 250 hours and 300 hours of light resistance test
The LER is shown in Table 2. The BLER increases earlier in the order of the thickness of the Ag reflection layer. BLER CD standard value is 22
0 count / sec. When the test time is 250 hours, it is understood that the light resistance of the samples 1, 2, and 4 is good. In addition, for 300 hours, sample 1,
For only 4, the BLER value was within the CD standard value, and the light resistance was good. In consideration of the above, the result that the sample having a high Ag film thickness has good light resistance is obtained.

[0023]

[Table 2]

<Evaluation of Initial Characteristics> The initial characteristics of the samples shown in Table 1 were evaluated. Sony CD-R drive CD
Writing was performed on the entire surface at double speed using W900E.
CD-CATS for the degree of modulation in the written sample
And the effect of the Ag film thickness on the characteristics was examined. In Table 3,
Modulation degree I3 / Itop, I11 / Itop of each sample
Shows the value of Samples 1 and 4 having a high Ag film thickness have a lower degree of modulation than Sample 2. Further, Sample 4 having a higher sputter output has a lower modulation degree than Sample 1.

[0025]

[Table 3]

According to the light resistance test and the evaluation of the initial characteristics, the CD-ROM having high light resistance and good signal characteristics can be obtained.
The Ag reflection layer of the R disk can be defined under the conditions shown in Table 4.

[Table 4]

Example 2 An optical recording medium having the structure shown in FIG. 1 was prepared. First, 1.6 μm
A recording layer 2 was formed by dissolving a phthalocyanine dye in a solvent as a light absorbing layer on a polycarbonate resin substrate 1 on which continuous pitch grooves were transferred, applying the solution by a spin coating method, and then drying to form a recording layer 2. Next, the Ag reflective layer 3 was formed on the recording layer 2 by sputtering so that the minimum thickness of the recording area was 100 nm.
The thickness was formed. The target had a purity of 99.
99% Ag was used, and the sputtering gas had a purity of 9%.
9.9% Ar gas was used. The flow rate of Ar gas was set to 60 sccm. Next, an ultraviolet curable resin was applied on the Ag reflective layer 3 and cured by irradiation with ultraviolet light to form a protective layer 4. Finally, an ultraviolet curable ink was applied by screen printing and cured by ultraviolet light to form an upper protective layer 5.

Comparative Example 1 A sample was prepared under the same conditions as in Example 2 except that the flow rate of Ar gas was 10 sccm.

Example 3 A sample was prepared under the same conditions as in Example 2 except that the flow rate of Ar gas was 120 sccm. In addition, in this flow rate, Example 2
The film thickness distribution becomes less uniform compared to
Since the film thickness was reduced, a sputtering time 1.5 times that of Example 2 was required to secure a minimum film thickness of 100 nm.

<Evaluation> A CD signal was recorded on the samples of Examples 2 and 3 and Comparative Example 1 by a CD-R recorder (CDE100 manufactured by Yamaha Corporation). Her samples
65,000 using SUNEST made by aeus
Light irradiation was performed for 250 hours at an illuminance of lux, and the block error rate (BLER) of the inner peripheral portion before and after irradiation was compared. Table 5 shows the results. BLER CD standard value is 22
0 count / s or less. When the signal characteristics of the third embodiment were checked, the 11T modulation degree was 1.5% lower than that of the second embodiment.

[0031]

[Table 5]

[0032]

According to the optical recording medium of the first aspect, since the thickness of the metal reflection layer is 100 nm or more and is not easily affected by minute defects of 100 nm or less, defects generated by prolonged irradiation of light are possible. Since the destruction of recorded information due to damage to the reflective layer when creating the upper protective layer can be prevented or reduced,
Light resistance can be increased.

According to the optical recording medium of the second aspect, the upper limit of the thickness of the metal reflection film is set to 200 nm or less, and the heat capacity of the metal film is kept low. And a high degree of modulation can be obtained while maintaining light resistance.

According to the optical recording medium of the third aspect, since the uniformity of the metal reflection film thickness is high, uniform characteristics in light resistance can be obtained.

According to the optical recording medium of the fourth aspect, since the metal reflective film is sputtered at an output of 4 kW or less, a high sputter rate can be obtained while minimizing damage to the reflective layer during film formation. In addition, a film having a thickness greater than that specified in claim 1 can be formed in a short time while maintaining high light resistance and a high degree of modulation.

According to the method of manufacturing an optical recording medium of the present invention, a gas containing Ar as a main component is used as a sputtering gas when the metal reflection layer is formed by sputtering, and the gas flow rate is 30 sccm or more. By doing
Even when Ag is used for the reflective layer, an optical recording medium with good light resistance can be obtained.

According to the method of manufacturing an optical recording medium of the present invention, when the metal reflection layer is formed by sputtering, the gas flow rate of the sputtering gas is set to 100 sccm or less, so that even when Ag is used for the reflection layer, An optical recording medium having good light resistance, uniform film thickness distribution, and good signal characteristics can be obtained.

According to the method of manufacturing an optical recording medium of the present invention, by setting the Ag ratio of the metal reflection layer to 99 to 100 atomic%, an optical recording medium having good signal characteristics such as reflectance can be obtained. it can.

According to the method for manufacturing an optical recording medium of the eighth aspect, it is possible to obtain a product applicable to a laminated medium such as a DVD-R.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing a configuration example of an optical recording medium of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Transparent substrate 2 Recording layer 3 Metal reflective layer 4 Lower protective layer 5 Upper protective layer

Claims (8)

[Claims] Claims: 1. A cyanine-based resin on at least a transparent substrate.
A reflective layer of Ag or a metal containing Ag is provided via a recording layer containing either a phthalocyanine-based or azo-based organic dye, and a lower protective layer having a thickness of 2 μm or more made of an ultraviolet curable resin is further formed on the reflective layer. Optical recording of information with a structure having a layer and an upper protective layer containing an ultraviolet curable resin thereon
An optical recording medium for performing reproduction or erasing, wherein the metal reflective layer is formed by sputtering film formation, and the minimum film thickness of a recordable / reproducible region is 100 nm or more. 2. The optical recording medium according to claim 1, wherein a minimum thickness of the metal reflective layer in a recording / reproducing area of the recording medium is 200 nm or less. 3. The optical recording medium according to claim 1, wherein the in-plane variation of the recordable / reproducible region of the film thickness of the metal reflective layer is 50% or less. 4. The optical recording medium according to claim 1, wherein the sputtering output at the time of forming the metal reflective layer is 4 kW or less. 5. A recording layer containing an organic dye on at least a transparent substrate, a metal reflection layer containing 80 to 100 atomic% of silver on the recording layer, and an ultraviolet ray on the reflection layer. In a method of manufacturing an optical recording medium for optically recording / reproducing or erasing information having a structure having a protective layer made of a cured resin, a metal reflective layer is formed by sputtering, and a gas mainly containing Ar is used as a sputtering gas. And a gas flow rate of a sputtering gas of 30 sccm or more. 6. A gas flow rate of the sputtering gas is 100 s.
6. The method for manufacturing an optical recording medium according to claim 5, wherein the optical recording medium is not more than ccm. 7. The method for manufacturing an optical recording medium according to claim 5, wherein the metal reflection layer contains 99 to 100 atomic% of silver. 8. The method for manufacturing an optical recording medium according to claim 5, further comprising a step of bonding the protective layer side to another substrate.