JPH0714222A - Manufacture of optical recording medium - Google Patents

Abstract

PURPOSE:To manufacture an optical recording medium having a protective layer for sufficiently protecting a reflecting layer and maintaining its reflectivity by controlling the cure shrinkage of the protective layer containing an ultraviolet curing resin within a specific range. CONSTITUTION:An optical recording medium is formed by successively forming a recording layer 2, reflecting layer 3, and protective layer 4 on a substrate 1. The protective layer 4 for protecting the reflecting layer 3 contains an ultraviolet curing resin, and the cure shrinkage X of the layer 4 is controlled to 6%<=X<=10% by adjusting the irradiating amount with ultraviolet rays. The protective layer serves to sufficiently protect the reflecting layer 3 and maintain its reflectivity.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an optical recording medium, and more particularly to a method for manufacturing a write-once type optical recording medium.

[0002]

2. Description of the Related Art As a conventional write-once type optical recording medium, for example, one having a structure shown in the perspective view of FIG. In FIG. 1, reference numeral 1 denotes a translucent donut plate-shaped substrate. A recording layer 2 made of an organic dye is formed on the substrate 1. The recording layer 2 absorbs the laser light emitted through the substrate 1 to generate heat, and is melted, evaporated, sublimated, deformed or modified,
It is a layer having a function of forming pits on the surfaces of the recording layer 2 and the substrate 1.

A reflective layer 3 is formed on the recording layer 2. The thickness of the reflective layer 3 is usually about 50 to 200 nm. Since a reading error is likely to occur when the reflective layer 3 is scratched, a protective layer 4 for protecting the reflective layer 3 and the like is formed on the reflective layer 3. An ultraviolet curable resin is used for the protective layer 4 because it can be easily applied and cured.

It is desired that the optical recording medium can be reproduced by a player used for an existing compact disc. Therefore, it is practically required that the reflectance is 65% or more.

Further, it is practically required that the protective layer has a pencil hardness of H or more in order to protect the reflective layer and the recording layer.

[0006]

By the way, in the optical recording medium having the above-mentioned structure, its reflectance changes depending on the film thickness of the recording layer and the shape of the interface between the recording layer and the reflective layer. It is known. That is, the delicate layer containing a dye, which is formed in the groove portion on the substrate like the recording layer of the optical recording medium having the above-mentioned structure, may have a recording layer of a recording layer depending on the manufacturing conditions of the reflective layer and the protective layer provided on the recording layer. The film thickness and the shape of the interface change, and the reflectance decreases.

For this reason, the present inventor has made various investigations on the manufacturing conditions of the reflective layer and the protective layer, and paid attention to the volume shrinkage during curing of the protective layer containing the ultraviolet curable resin. The volumetric shrinkage rate of the ultraviolet curable resin before and after curing (hereinafter referred to as curing shrinkage rate) generally changes depending on the irradiation amount of ultraviolet rays. When the irradiation amount is large, the curing shrinkage ratio is large, and when the irradiation amount is small, the curing shrinkage ratio is small. However, it is known that the curing shrinkage rate has an upper limit.

An object of the present invention is to provide a method for producing an optical recording medium having a protective layer which does not reduce the reflectance and can exert a sufficient protective function for the reflective layer.

[0009]

In order to achieve the above-mentioned object, a method for producing an optical recording medium of the present invention comprises a recording layer containing a dye on a transparent substrate, a reflective layer, and an ultraviolet curing. In the method for producing an optical recording medium, which is formed by sequentially laminating a protective layer containing a mold resin, the curing shrinkage rate X of the protective layer is 6
It is characterized in that it is controlled such that% ≦ X ≦ 10%.

[0010]

In the present invention, since the curing shrinkage rate of the protective layer containing the ultraviolet curable resin is set within a specific range, it is possible to suppress the change in the thickness of the recording layer and the change in the shape of the interface between the recording layer and the reflective layer. And, the protective layer exerts a necessary protective function.

[0011]

EXAMPLES Examples of the present invention will be described in detail below.

A feature of the present invention is that the curing shrinkage rate X of the protective layer 4 of the optical recording medium having the structure shown in FIG. 1 is 6% ≦ X ≦.
It is to be in the range of 10%. When the curing shrinkage rate X exceeds 10%, the volumetric shrinkage rate of the protective layer 4 increases, which reduces the film thickness of the recording layer 2 and disturbs the interface between the recording layer 2 and the reflective layer 3. There is an inconvenience that the reflectance decreases. On the other hand, if the curing shrinkage X is less than 6%, the volume shrinkage of the protective layer 3 becomes small, and the protective layer 4 is not sufficiently cured, so that the protective function cannot be exerted and the reflective layer is apt to be damaged. .

Here, as for the curing shrinkage, the specific gravity of the resin before curing is measured by JIS K-6835, and the measured value is taken as M, and the specific gravity of the resin after curing is JIS K-6.
911, and the measured value is N, the equation is

[0014]

[Equation 1] Curing shrinkage (%) = (NM) × 100 ÷ N (1)

The curing shrinkage rate X can be set within the above specific range by controlling the integrated light amount of the ultraviolet rays with which the protective layer 4 is irradiated.

[Comparative Example 1] Width 0.6 μm, depth 2000
Thickness with spiral groove of Å at 1.6μm intervals 1.
Cyanine dye N on a 2 mm polycarbonate substrate
A disk in which K-2929 (manufactured by Japan Photosensitive Dye Research Institute Co., Ltd.) is applied in a solution containing 2.5 wt% of ethanol by a spin coating method and the solvent is evaporated to form a recording layer having a thickness of 1300Å. Was produced. Next, 1000 A of Au is applied to the dye-coated surface of the dye-coated disk by a sputtering method.
Å The film was formed. Next, an acrylic UV-curable resin SD-301 (manufactured by Dainippon Ink and Chemicals, Inc.) was formed on the Au film forming surface.
Was applied by a spin coating method to form an uncured layer to be a protective layer having a thickness of 4 ± 1 μm.

The uncured layer has an integrated light amount of 150 mJ / c.
Ultraviolet rays were radiated so as to obtain m ² . However, as the light receiver of the integrated photometer, one having a sensitivity wavelength range of 330 to 390 nm was used.

The curing shrinkage of the protective layer cured under the above irradiation conditions was 4%.

Example 1 An uncured layer formed by the same method as in Comparative Example 1 had an integrated light quantity X (mJ / cm ² ) of 25.
Ultraviolet rays were radiated so as to obtain 0 mJ / cm ² . However, the light receiver of the integrating photometer is in the sensitivity wavelength range 330 to 390.
The thing of nm was used.

The curing shrinkage of the protective layer cured under the above irradiation conditions was 6%.

[Example 2] An uncured layer formed in the same manner as in Comparative Example 1 had an integrated light quantity X (mJ / cm ² ) of 35.
Ultraviolet rays were radiated so as to obtain 0 mJ / cm ² . However, the light receiver of the integrating photometer is in the sensitivity wavelength range 330 to 390.
The thing of nm was used.

The curing shrinkage of the protective layer cured under the above irradiation conditions was 8%.

Example 3 An uncured layer formed by the same method as in Comparative Example 1 has an integrated light amount X (mJ / cm ² ) of 500.
Ultraviolet rays were radiated so as to obtain mJ / cm ² . However,
The light receiver of the integrated photometer has a sensitivity wavelength range of 330 to 390 nm.
I used the one.

The curing shrinkage of the protective layer cured under the above irradiation conditions was 10%.

[Comparative Example 2] An uncured layer formed by the same method as in Comparative Example 1 has an integrated light amount X (mJ / cm ² ) of 75.
Ultraviolet rays were radiated so as to obtain 0 mJ / cm ² . However, the light receiver of the integrating photometer is in the moving wavelength range 330 to 390.
The thing of nm was used.

The curing shrinkage of the protective layer cured under the above irradiation conditions was 12%.

Table 1 shows the results of a pencil hardness test conducted to measure the reflectance of Examples 1 to 3 and Comparative Examples 1 and 2 and to measure the degree of curing of the protective layer.

[0028]

[Table 1]

As shown in Table 1, in Examples 1 to 3, the reflectance exceeds 65%, which is compatible with the compact disc. In addition, in Examples 1 to 3, the pencil hardness is H or more, and it can be seen that the protective function is practically sufficient.

However, in Comparative Example 1, the reflectance exceeds 65%, but the pencil hardness of the protective layer is HB, the protective function is insufficient, and the reflective layer is easily scratched. In Comparative Example 2, the pencil hardness exceeds 2H, but the reflectance is less than 65% and the compatibility with the compact disc is not achieved.

As described above, when the curing shrinkage is 6% or more and ± 10% or less, an optical recording medium satisfying the reflectance and the protective function can be obtained. Also, with respect to an optical recording medium having a protective layer formed by using another ultraviolet curable resin, the same effect was obtained when the reflectance was measured and the durability test was performed while changing the irradiation amount of ultraviolet rays.

In the above-mentioned Examples 1 to 3, the cyanine dye was used as the dye for the recording layer. However, as the dye for the recording layer, cyanine dyes such as merocyanine and phthalosilanin are preferably used. You can
Specifically, indodicarbocyanine, 1,1'dibutyl 3,3,3 ', 3' tetramethyl 4,5,4 ', 5' dibenzoindodicarbocyanine perchlorate (Co., Ltd.)
Made by Japan Photosensitive Dye Research Institute: Product number NK3219), 1,1 '
Dibutyl 3,3,3 ', 3' Tetramethyl 5,5 'Diethoxyindodicarbocyanine iodide, 1,1'
Dibutyl 3,3,3 ', 3' tetramethyl 5,6
5 ', 6' Tetramethoxyindodicarbocyanine perchlorate, 1,1'dibutyl 3,3,3 ', 3' tetramethyl 5,7,5 ', 7' tetramexindodicarbocyanine perchlorate, 1, 1'diethyl 3,3
3 ', 3' tetramethyl indotricarbocyanine perchlorate and the like can be mentioned. Further, the metal-containing azo dyes can be used alone or in combination.

[0033]

As described above, the manufacturing method of the present invention provides an optical recording medium having a medium characteristic that the reflectance and the protective function of the protective layer are good by optimizing the curing shrinkage rate of the protective layer. can do.

[Brief description of drawings]

FIG. 1 is a perspective view, partly in section, showing the structure of a write-once type optical recording medium.

[Explanation of Codes] 1 substrate 2 recording layer 3 reflective layer 4 protective layer

Claims (1)

[Claims] 1. A method of manufacturing an optical recording medium, comprising: a recording layer containing a dye, a reflective layer, and a protective layer containing an ultraviolet curable resin, which are sequentially laminated on a transparent substrate. A method for producing an optical recording medium, wherein the curing shrinkage rate X of the layer is controlled to 6% ≦ X ≦ 10%.