JPH08279183A - Optical information recording medium and its production - Google Patents

Abstract

PURPOSE: To make it possible to exactly record and reproduce information over a long period of time by providing a disk with a recording layer while covering this recording layer with a reflection layer in the inner and outer peripheral parts of the disk so as to prevent the ends of the recording layer from coming into contact with a protective layer. CONSTITUTION: This optical information recording medium is constituted by successively laminating the recording layer 2 consisting of org. dyestuff, such as cyanine dyestuff, the first reflection layer 3, the second reflection layer 4 and the protective layer 6 consisting of a UV curing resin, etc., on a transparent substrate 1 consisting of a polycarbonate. The end of the recording layer 2 is laminated in the inner and outer peripheral parts of the disk in such a manner that the second reflection layer 4 covers the end, thereby preventing the direct contact of the protective layer 6 with the recording layer 2. As a result, the protective layer 6 having high hygroscopicity and the recording layer 2 are no longer adhered any more by the reflection layer 4 having the low hygroscopicity and, therefore, the moisture permeated through the protective layer 6 does not penetrate the recording layer 2 near the outermost peripheral end 8 and inner peripheral part of the disk any more. Then, the recording layer is no longer deteriorated and the recording and reproducing under optimum conditions are executable over a long period of time.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical information recording medium capable of recording and reproducing information by using a light beam, and a manufacturing method thereof.

[0002]

2. Description of the Related Art Compact disc (CD: Compact Di
sk) compatible write-once CD (CD-R: Compact)
Disk-Recordable) has a structure in which a recording layer made of an organic dye such as a cyanine dye, a reflective layer made of a metal such as gold, and a protective layer made of an ultraviolet curable resin are sequentially laminated on a transparent substrate. It is disclosed in JP-A-2-132656 and JP-A-2-168446.

The first characteristic required for the CD-R is that no peeling from the inner peripheral portion or the outer peripheral portion and deterioration of the recording layer occur even when the CD-R is stored under conditions of high temperature and high humidity for a long time. There is. Therefore, it is necessary to prevent the end portions of the recording layer and the reflective layer from being exposed at the inner peripheral portion and the outer peripheral portion of the disc. Further, as the second characteristic required for the CD-R, in order to comply with the CD standard (Red Book), it is necessary to satisfy the mirror portion reflectance of 70% or more.

FIG. 6 is a schematic diagram showing a cross-sectional structure of a conventional CD-R. An optical information recording medium having a structure in which the transparent substrate 1 and the protective layer 6 are in close contact with each other on the inner and outer peripheral portions of the disc as shown in FIG. 6 is disclosed in Japanese Patent Laid-Open No. 4-198004.

Here, the manufacturing method of the optical information recording medium described in the above publication is as follows. The recording layer 2 is laminated on the transparent substrate 1 by spin coating a solution in which a cyanine dye or the like is dissolved in a solvent such as cellosolve from the inner peripheral portion toward the outer peripheral portion.

Next, a mask is placed in the inner and outer peripheral regions of the transparent substrate so that the reflective layer 5 is not formed in this region, and the reflective layer 5 of gold or the like is masked by magnetron sputtering. It is formed in a region other than the region.

As described above, a monomer liquid of an ultraviolet curable resin such as an epoxy resin is spin-coated so as to cover the entire main surface of the transparent substrate 1 on which the reflective layer 5 is formed, and is protected by curing by irradiation with ultraviolet rays. Form layer 6.

At this time, the recording layer 2 in the inner peripheral portion and the outer peripheral portion of the disc where the reflective layer 5 is not formed is dissolved and removed by the protective layer 6, and the transparent substrate 1 and the protective layer 6 are directly removed in this region. The discs having the structure shown in FIG. 6 are obtained.

Further, before forming the protective layer 6, a method of removing the recording layer 2 in the inner peripheral portion and the outer peripheral portion of the disc where the reflective layer 5 is not formed with an alcohol such as ethanol or a solvent such as cellosolve. Is also known.

[0010]

However, in the optical information recording medium, the recording layer and the protective layer are in direct contact with each other in the inner peripheral portion and the outer peripheral portion. UV-curing resins such as epoxy resins and acrylic resins are generally used for the protective layer. However, these resins have high hygroscopicity and easily transmit moisture, so the inner and outer circumferences of the disc Part of the recording layer is deteriorated by the permeated water.

FIG. 7 shows a layout of a disc defined by the CD-R standard. in this way,
The inner peripheral portion of the CD-R includes a PCA (Power Calibration Area) 9 which is an area for determining the recording power, a PMA (Program Memory Area) 10 in which additional recording information is recorded, disk information and information of recorded tracks. Lead-in
Area 11 is arranged, and a lead-out area is provided on the outer periphery.
12 important information areas are arranged. Therefore, if the recording layers on the inner and outer peripheral portions are deteriorated, recording may not be performed under optimal conditions, or recorded data may not be reproduced in a good state.

Further, in the CD-R standard, a mirror portion reflectance of 70% or more is specified in order to be compatible with CD. Therefore, the reflectance is saturated with expensive gold as a material of the reflecting layer 5. The film thickness (about 80 nm) must be used, which is a cause of high cost in CD-R production.

Further, in JP-A-3-201228, an interference layer for increasing the reflectance is provided between the recording layer 2 and the reflecting layer 5, so that the material of the reflecting layer 5 has a reflectance higher than that of gold. Although an optical information recording medium in which aluminum or the like is used because of low cost and low material cost is disclosed, there is a problem that a margin of reflectance becomes narrower than that in the case of using gold. Further, when an inorganic dielectric is used as the interference layer, there is a problem that the film formation time becomes long, and when a resin is used, it is difficult to control the film thickness.

[0014]

According to the invention described in claim 1, the present invention is an optical information recording medium comprising a substrate and a recording layer, a reflective layer and a protective layer laminated in this order on the substrate. hand,
The substrate has a region without the recording layer, the reflective layer covers the recording layer and adheres to the substrate inside and outside the recording layer, and the protective layer covers the reflective layer and adheres to the substrate inside and outside the reflective layer. It is characterized by that.

According to the invention described in claim 2, claim 1
The optical information recording medium as described above, characterized in that the reflective layer comprises two layers.

According to a third aspect of the present invention, there is provided a method of manufacturing an optical information recording medium, which comprises a recording layer forming step of forming a recording layer on a substrate, and an inner peripheral portion and an outer peripheral portion of the substrate. A first masking step of attaching the first mask of
A step of forming a first reflective layer in a region other than the region covered with the mask, a recording layer removing process of removing the recording layer in the region covered with the first mask, and a substrate A second inner surface of the second mask for covering an inner area than the area covered with the first mask and an outer peripheral area of the outer surface covered with the outer surface than the area covered by the first mask. A second masking step of mounting a mask, a second reflective layer forming step of forming a second reflective layer in an area other than the area covered by the second mask, and an area in which the second reflective layer is formed. Also has a protective layer forming step of forming a protective layer from the inner region to the inner region and to the outer region to the outer region.

[0017]

The optical information recording medium according to claim 1 of the present invention comprises:
At the inner and outer peripheries of the disc, a reflective layer having low hygroscopicity is formed so as to cover the end of the recording layer so that the protective layer having high hygroscopicity and the recording layer do not adhere to each other. There is no deterioration of the recording layer due to permeation of water that has permeated the protective layer into the recording layers at the peripheral portion and the outer peripheral portion, and recording and reproduction can be performed under optimum conditions for a long period of time.

Further, in the optical information recording medium according to the second aspect of the present invention, since the reflective layer has a two-layer structure, it is possible to stack reflective layers of two different materials, which is expensive. The gold film thickness can be reduced.

Further, according to the method of manufacturing an optical information medium according to the third aspect of the present invention, the inner peripheral portion and the outer peripheral portion of the disk respectively have regions having no recording layer, and the reflective layer is the inner peripheral portion of the substrate. It is possible to manufacture an optical information recording medium in which the protective layer is in contact with the substrate over the recording layer in the outer and outer portions, and the protective layer is in contact with the substrate over the reflective layer in the inner and outer peripheral portions of the substrate. In addition, it is possible to manufacture an optical information recording medium having a reflective layer made of two different materials.

[0020]

FIG. 1 is a schematic sectional view showing an embodiment of the optical information recording medium of the present invention. On a transparent substrate 1 made of polycarbonate, a recording layer 2 made of an organic dye such as a cyanine dye, a first reflective layer 3, a second reflective layer 4 and a protective layer 6 made of an ultraviolet curable resin were laminated in order. .

The feature of the optical information recording medium of the present invention is that, as shown in FIG. 1, the end of the recording layer 2 is covered with the second reflective layer 4 at the inner and outer peripheral portions of the disc. It means that the protective layer 6 and the recording layer 2 are not in direct contact with each other because they are laminated.

Further, the transparent substrate 1 is not limited to the polycarbonate resin, and a plastic material such as an acrylic resin, a polyolefin resin or an epoxy resin, a glass plate or the like may be used as conventionally known.

The recording layer 2 is not limited to cyanine-based organic dyes, and organic dyes such as phthalocyanine-based, naphthalocyanine-based, naphthoquinone-based, and azo-based dyes may be used.

Further, the first reflective layer 3 and the second reflective layer 4
Is a metal such as gold, silver, copper, aluminum, nickel, chromium or an alloy thereof, and the first reflective layer 3
The second reflective layer 4 and the second reflective layer 4 may be made of the same material or different materials.

Next, a method of manufacturing the optical information recording medium of the present invention will be described with reference to the flow charts. FIG. 2 is a flow chart showing the steps of the method for manufacturing the information recording medium of the present invention. First, a solution in which an organic dye such as a cyanine dye is dissolved in a solvent such as methyl cellosolve is applied to the entire surface of the transparent substrate 1 having grooves or pits by a spinner device to form a recording layer 2 having a film thickness of about 110 nm. To form.

The transparent substrate 1 having the entire surface coated with the recording layer 2 has an inner peripheral portion (a region having a width of about 12.5 mm from the end 7 of the center hole of the disc) and an outer peripheral portion (1.5 m from the outermost end 8 of the disc).
a first mask is attached to cover the
The first reflective layer 3 made of gold or the like is formed to a thickness of about 80 nm in a region other than the region covered with the mask by the sputtering method.

Subsequently, the first mask is removed, and the transparent substrate 1 having the recording layer 2 and the first reflective layer 3 formed thereon is mounted on the spinner device again. Then, while rotating the disc, a solvent such as ethanol, diacetone alcohol, or methyl cellosolve that dissolves the recording layer 2 and does not adversely affect the transparent substrate 1 is applied, and the region covered with the first reflective layer 3 is coated. The recording layer 2 in the area other than the above is dissolved and removed. In this case, since the first reflective layer 3 plays the role of a mask,
The recording layer 2 in the area covered with the reflective layer 3 is not attacked by the solvent.

As a method for dissolving and removing the recording layer 2 in the area other than the area covered with the first reflective layer 3, a gauze-like or cotton-like thing soaked with a solvent may be wiped off.

A second mask is attached to the inner peripheral portion and the outer peripheral portion of the transparent substrate 1 from which the recording layer 2 in the region other than the region covered with the first reflective layer 3 is removed. In the second mask, the second reflective layer 4 covers the end portion of the recording layer 2, and the second reflective layer 4 serves as the transparent substrate 1 in the inner and outer peripheral regions where the recording layer 2 is removed. It is necessary to make contact.

For this reason, the second mask covers the inner region of the substrate inside the region covered by the first mask, and the outer periphery thereof is covered by the first mask. It must be shaped so as to cover more outside than the closed area. The second mask used in this example covers an area of about 12.0 mm width from the disk center hole end portion 7 in the inner peripheral portion of the transparent substrate 1, and the outermost peripheral edge portion 8 to 1 of the disk in the outer peripheral portion. The shape is such that it covers a region having a width of 0.0 mm.

The disk on which the second mask was mounted was again set in the sputtering apparatus, and the second reflective layer 4 of aluminum or the like was formed to a thickness of about 130 nm in the area other than the area covered by the second mask. To do.

Next, the disk from which the second mask was removed was placed in a spinner device, rotated, coated with a monomer solution of an ultraviolet curable resin, and cured by irradiation with ultraviolet rays.
The protective layer 6 is formed. Here, the protective layer 6 is the second reflective layer 4
From the inner area of the inner circumference than the area where
In addition, the monomer solution of the UV curable resin is applied to the second reflective layer 4 on the inner peripheral portion so that the outer peripheral portion covers the outer region.
It is necessary to apply from the inside of the area covered with.

A linear velocity of 1.4 m / s and a laser power of 5.0 mW were applied to the entire surface of the optical information recording medium of the present invention manufactured as described above and the optical information recording medium of the conventional structure shown in FIG.
The average block error of the outer peripheral part (diameter 115 mm to 118 mm) when a digital signal modulated by EFM (Eight to Fourteen Modulation) was recorded and the temperature and humidity cycle test (archival test) of JIS C5024M-1 was performed. The rate change was inspected. In addition, 1 of this test
The cycle corresponds to about one year under normal circumstances.

FIG. 3 shows the results of the archival test. As described above, since the optical information recording medium of the present invention has a smaller change in block error rate in the archival test than the conventional optical information recording medium, the recording layer 2 in the outer peripheral portion is less deteriorated.

Next, an unrecorded optical information recording medium of the present invention and a conventional optical information recording medium were subjected to a JISC5024M-1 temperature / humidity cycle test, and a linear velocity of 1.4 m / s at every arbitrary cycle. An EFM-modulated digital signal was recorded at a laser power of 5.0 mW, the block error rate was measured each time, and a test (shelf test) was performed to measure the change in the block error rate.

FIG. 4 shows the result of the shelf test. Thus, it can be seen that the optical information recording medium of the present invention has a smaller change in block error rate in the shelf test than the conventional optical information recording medium. This is because the area of the recording layer 2 including the PCA area and the like in the inner peripheral portion of the conventional optical information recording medium is deteriorated, and as a result, the recording sensitivity of the PCA area is largely deviated from the optimum recording sensitivity. is there.

FIG. 5 shows the dependence of the reflectance of the mirror portion on the gold film thickness when gold is used for the first reflective layer 3 and aluminum is used for the second reflective layer 4 in the optical information recording medium of the present invention. It is a graph which shows the result of calculation. Here, the transparent substrate 1 has a refractive index n = 1.5, a thickness of 1.2 mm, and the recording layer 2 has a complex refractive index n = 2.5-0.07i, a film thickness of 130 nm, and a cyanine dye. Complex refractive index n of the reflective layer 3 (gold) of
Calculations were performed assuming that the complex refractive index of the second reflective layer 4 (aluminum) was n = 1.6-5.5i and the film thickness was 60 nm. The reproduction wavelength was 780 nm. For comparison, the dependence of the reflectance of the mirror portion in the conventional CD-R on the gold film thickness is shown.

In the conventional CD-R, the reflectivity of the mirror portion reaches 70% when the film thickness of the gold of the reflective layer 5 is 40 nm,
In the optical information recording medium of the present invention, the reflectivity of the mirror portion is saturated at nm, whereas the gold thickness of the first reflective layer 3 is 1
At 0 nm, the reflectance of the mirror portion reaches 70%, and at 30 nm, the reflectance of the mirror portion is saturated.

[0039]

As described above, the optical information recording medium of the present invention has a reflective layer having a low hygroscopic property so that the protective layer having a high hygroscopic property and the recording layer do not adhere to each other on the inner and outer peripheral portions of the disc. Is formed to cover the edge of the recording layer,
The deterioration of the recording layer due to the permeation of water that has permeated the protective layer into the recording layers on the inner and outer peripheral portions of the disc is small, and recording can be performed under optimum conditions for a long period of time. In addition, it is possible to reproduce the data in a good state for a long period of time.

When the information recording medium of the present invention is applied to a CD-R or the like, it is not necessary to provide an interference layer as in the conventional case, and the expensive gold film thickness is less than half of the conventional case and 70% or more. Since the mirror part reflectance of 1 is obtained, the disk can be manufactured at low cost.

Further, according to the method for manufacturing an optical information medium of the present invention, the inner peripheral portion and the outer peripheral portion of the disc respectively have regions having no recording layer, and the reflective layer has the inner peripheral portion and the outer peripheral portion of the substrate. In the optical information recording medium which is in contact with the substrate over the recording layer, and the protective layer is in contact with the substrate over the reflective layer in the inner peripheral portion and the outer peripheral portion of the substrate. It is possible to manufacture an optical information recording medium having a reflective layer of various materials.

[Brief description of drawings]

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

FIG. 2 is a flowchart showing steps of a method for manufacturing an information recording medium of the present invention.

FIG. 3 is a view showing a result of an archival test in an example of the present invention.

FIG. 4 is a diagram showing a result of a shelf test in an example of the present invention.

FIG. 5 is a graph showing the results of calculation of the gold film thickness dependency of the reflectance of the mirror portion in the example of the present invention.

FIG. 6 is a schematic diagram showing a cross-sectional structure of a conventional CD-R.

FIG. 7 is a schematic diagram showing a layout of a disc defined by the CD-R standard.

[Explanation of symbols]

 1 Transparent Substrate 2 Recording Layer 3 First Reflection Layer 4 Second Reflection Layer 5 Reflection Layer 6 Protective Layer 7 Disc Center Hole Edge 8 Disc Outermost Edge 9 PCA 10 PMA 11 Lead-in Area 12 Lead-out Area

Claims (3)

[Claims] 1. An optical information recording medium comprising a substrate and a recording layer, a reflective layer and a protective layer laminated in this order on the substrate, wherein the substrate has a region without the recording layer, and the reflective layer. Is a light that covers the recording layer and adheres to the substrate inside and outside the recording layer, and the protective layer covers the reflective layer and adheres to the substrate inside and outside the reflective layer. Information recording medium. 2. The optical information recording medium according to claim 1, wherein:
An optical information recording medium, wherein the reflective layer comprises two layers. 3. A recording layer forming step of forming a recording layer on a substrate, a first masking step of mounting a first mask for covering an inner peripheral portion and an outer peripheral portion of the substrate, and the first mask. A first reflective layer forming step of forming a first reflective layer in an area other than the area covered by the mask; a recording layer removing step of removing the recording layer in the area covered by the first mask; The inner circumference of the first mask covers more inside than the area covered by the first mask, and the outer circumference of the first mask covers the first mask.
A second masking step of mounting a second mask for covering the outer side of the area covered by the second mask;
A second reflective layer forming step of forming a second reflective layer in a region other than the region covered with the mask of, and an inner peripheral region of the inner peripheral part of the region in which the second reflective layer is formed, And,
A method of manufacturing an optical information recording medium, characterized by comprising a protective layer forming step of forming a protective layer on an outer peripheral portion of the peripheral portion.