JPH0650574B2 - Light disk - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disc, and more particularly to an optical disc of optical reading type such as a digital audio disc, an optical video disc and a memory disc.

[Background of the Invention]

Conventionally, a disc is made of glass, transparent plastics (polymethylmethacrylate, polymethylmethacrylate,
A transparent substrate 1 such as polycarbonate), a base layer 2 having a groove-shaped or hole-shaped concavo-convex formed thereon for a servo track, and Bi, I formed on the base layer 2.
Two optical disk substrates consisting of a recording metal film 3 of n, Te, Se, As, Pb, Sn or the like are held by a housing 4 so that the recording metal films 3 face each other at a constant interval. The case and the transparent substrate are sealed with an adhesive (not shown).

Then, the recording metal film 3 is irradiated with a light beam, and the recording metal film in the irradiated portion is removed to form a unit of information.

Such an optical disc has been conventionally manufactured as shown in FIGS. 2 (a) to (c). That is, an ultraviolet curable resin is sandwiched between a stamper 5 made of a metal such as nickel having a predetermined unevenness and the transparent substrate 1, and the resin is ultraviolet cured to form a base layer 2 (see FIG. 2 (a)). ), The metal stamper 5 is peeled off (FIG. 2 (b)), the recording metal film 3 is formed on the underlying layer having irregularities (FIG. 2 (c)), and these two optical disk substrates are The recording metal films were made to face each other with a constant interval by the casing, and the casing and the optical disk substrate were adhered.

The ultraviolet curable resin composition used for the above-mentioned underlayer must satisfy the following conditions. That is, (a) The cured product is optically transparent.

(B) Adhere well to a transparent substrate such as glass or transparent plastic.

(C) Easy to peel off from the stamper.

(D) The recording metal film is rapidly melted and removed by the irradiation of the light beam, and a good round hole is likely to be formed.

(E) There is no change in the formation of the recording metal film due to moisture absorption or swelling of the metal film due to moisture absorption after long-term use, and no corrosive substances eluted from the cured product due to moisture absorption for recording. Do not oxidize the metal film and increase the transmittance of the metal film. That is, the recorded signal can be accurately read even in a moisture absorbing environment.

(F) The concave and convex grooves formed by vapor deposition of the recording metal film have excellent thermal stability, the depth and shape of the groove do not change, and cracks do not occur in the metal film.

(G) Mechanical strength that can withstand high speed rotation of 500 rpm or more.

is necessary.

However, the conventional ultraviolet curable resin composition, the above (a) ~
The condition (g) was not satisfied at the same time.

A typical conventional example is Japanese Patent Laid-Open No. 56-1279 relating to an optical disk.
There is No. 46.

[Object of the Invention]

An object of the present invention is to eliminate the above-mentioned drawbacks of the prior art and provide an optical disc with stable performance.

[Outline of Invention]

The present invention, in order to achieve the above objects, a mixture of 100 to 20 parts by weight of a compound represented by the following general formula (1) in the base layer: 20 to 80 parts by weight, a compound represented by the following general formula (2): Parts and 100 to 100 parts by weight of this mixture, a photopolymerization initiator 0.1 to 5.
It is characterized by using a cured ultraviolet curable resin composition containing 0 part by weight.

(However, R ₁ and R ₂ are hydrogen or a methyl group, n is an integer, and n =
5-12) If the compounding amount of the compound of the general formula (1) is more than 80 parts by weight, the releasability from the stamper, the moisture resistance of the cured product, and the heat resistance decrease. On the other hand, if the amount of the compound of the general formula (1) is less than 20 parts by weight, the molding strain becomes large due to curing shrinkage, and the cured product becomes brittle and weak in mechanical strength.

Furthermore, as the photopolymerization initiator necessary for rapidly curing the above composition, for example, the following ones are effective. That is, benzyls, benzoins, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether and other benzoins, 1-hydroxycyclohexylbenzophenone and other benzophenones, acetophenones, 2-chlorothioxanthone, 2-methylthioxanthone and other thioxanthones, Examples include anthraquinones such as 2-ethylanthraquinone and 2-methylanthraquinone, and benzyl ketals such as benzyldimethyl ketal. The amount of the photopolymerization initiator is the above general formula (1)
0.1 to 5.0 parts by weight is effective for 100 parts by weight of the total of (2). If it is less than 0.1 part by weight, the reactivity is lowered and various properties of the cured product are lowered. On the other hand, if the amount is more than 5.0 parts by weight, the reaction is too fast and the heat generation is large, resulting in cracks in the cured product or uneven curing, resulting in deterioration of various properties.

The above photopolymerization initiators may be used alone or in admixture of two or more.

Also, for the purpose of adjusting viscosity, adjusting hardness, adjusting thermal expansion coefficient, reducing hygroscopicity, and improving peelability from the stamper,
For example, the following acrylates and methacrylates may be used. That is, lauryl acrylate, lauryl methacrylate, tridecyl methacrylate, isobornyl acrylate, isobornyl methacrylate, trimethylolethane triacrylate, trimethylolethane trimethacrylate, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, etc. are useful. .

These are used alone or in combination of two or more. The mixing ratio is 0 to 40 parts by weight based on 100 parts by weight of the general formulas (1) and (2).

Furthermore, in order to further stabilize the adhesiveness of the resin when absorbing moisture, for example, a silane coupling agent as shown below can be added. That is, γ-acryloxypropyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, N-β- (N-vinylbenzylamino) ethyl-γ-aminopropyltrimethoxysilane.・ Monohalogen chloride is useful. These may be used alone or in combination of two or more. The mixing ratio is 0 to 6.0 parts by weight based on 100 parts by weight of the general formulas (1) and (2).

Example of Invention

 Hereinafter, the present invention will be described in more detail based on examples.

The ultraviolet curable resin component represented by the general formula (2),
Those represented by the chemical formulas (A) and (B) below were used.

In addition, in Comparative Examples, in addition to those exceeding the compounding range of the components for the present invention (the above general formulas (1) and (2)), the following (X), (Y),
The one represented by the chemical formula (Z) was used.

(Molecular weight: about 400) Next, methods for measuring various properties of the cured resin product are shown below.

(1) Recording sensitivity: A signal was recorded using a glass-based optical disc. Irradiate a laser beam on the Te-based recording film under the following conditions to melt and remove it, and a good round hole with a diameter of about 1 μm is made in the recording film, and it can be used practically “○”, the hole is not clean and practical Those that could not stand were marked with "x".

Disk rotation speed: 960 rpm Recording frequency: 2.5 MHz Semiconductor laser: Wavelength 830 nm Recording power: Approximately 7 mW (film surface) (2) Moisture resistance: The optical disk was left standing in 60 ° C, 95% RH for 100 hours for judgment.

Due to the moisture absorption, the shape of the groove of the recording metal film does not change, the film surface swells due to the swelling of the metal film, and the increase in the transmittance of the metal film caused by the oxidation of the metal film by the corrosive substances eluted from the cured resin does not occur. Those that can withstand practical use are marked with "○", and those that cause the above changes and are not practical can be marked with "×".

(3) Heat resistance: judged by leaving the optical disc at 100 ° C. for 4 hours.

The thermal stability of the uneven groove formed by vapor-depositing the recording metal film is excellent, the depth and shape of the groove do not change, and the metal film does not crack. Those that did not exist were marked with "x".

(4) Light transmittance: A resin plate having a thickness of 1 mm was prepared, and the light transmittance at 830 nm was measured with a spectrophotometer.

(5) Tensile strength: It is necessary as a guide for the mechanical strength of an optical disk that can withstand high-speed rotation of 500 rpm or more, and was determined for a cured resin at 250 ° C according to JIS K6911.

(6) Adhesiveness: After leaving the optical disc at 60 ° C, 95% RH for 100 hours, or after heating it at 100 ° C for 4 hours, it is adhered to a transparent substrate such as glass or transparent plastic (epoxy type, acrylic type). The ones that have no problem in practical use are marked with "○" and those with problems are marked with "x". The resin composition used for this is shown in Table 1. Nos. 1 to 12 are examples of the present invention, and Nos. 13 to 22 are comparative examples.

The characteristics of these UV-curable resin compositions when UV-cured are summarized in Table 2. Based on the above characteristics
The characteristics of (1), (2), (3), and (6) were measured using an actual machine. That is, 10 g of a UV-curable resin composition shown in Table 1 was sandwiched between a nickel stamper having grooves and pits and a glass plate having a diameter of 300 mm and a thickness of 1.2 mm.
/ Cm ² ( ^{2 to 20} g / cm ² , preferably 5 to 15 g / cm ² ) and then 150 mW / cm ² (50 to 400 mW / cm ² ,
The resin composition was cured by irradiation with ultraviolet rays of preferably 100 to 250 mW / cm ² ). Then, when the glass plate was peeled off from the stamper, the glass plate was peeled off between the stamper and the cured UV-curable resin composition, and the uneven portion on the stamper was accurately transferred onto the surface of the cured UV-curable resin composition. It was

After depositing a Te-based recording film on the uneven surface of the resin adhered to the glass plate to a thickness of about 250 Å by vapor deposition, the two glass plates are made facing each other with a space of about 1 mm. The peripheral part was adhered with an epoxy adhesive to prepare an optical disk, and the characteristics of the actual machine were obtained.

Comparing Table 1 and Table 2, Comparative Examples Nos. 13 and 15 in which the compound represented by the general formula (1) of the present invention is less than 20 parts by weight,
In both cases, the tensile strength was poor and brittle as compared with Examples Nos. 1-12. In addition, Comparative Examples Nos. 14 and 16 in which the compound represented by the general formula (1) is more than 80 parts by weight are both moisture resistant,
The heat resistance was poorer than that of Examples Nos. 1 to 12, and the releasability from the stamper was also poor.

Further, the comparative example No. 17 and the comparative example No. 18 in which the compounding amount of the photopolymerization initiator is less than the range of the present invention are both Examples No. 1 to 1.
Compared with No. 2, not only the moisture resistance but also the heat resistance, tensile strength and adhesiveness were significantly inferior.

In addition, Comparative Examples Nos. 19 and 21 using the conventional products were remarkably inferior in recording sensitivity, moisture resistance, heat resistance, and adhesiveness to Examples Nos. 1 to 12. Comparative example No. 2 using a conventional product
Nos. 0 and 22 have recording sensitivity, moisture resistance, and heat resistance in Example Nos. 1 to 12
It was significantly inferior to.

That is, the ultraviolet curable resin compositions satisfying all of these characteristics are those of Examples No. 1 to 12, and the resin compositions satisfying the operation characteristics and life characteristics of the actual device as an optical disk are those of Example No. 1. It was only .1-12.

〔The invention's effect〕

As described above, according to the present invention, an optical disk having high recording sensitivity, high density, and high reliability can be obtained by using a material obtained by curing the above ultraviolet curable resin composition as the underlayer.

[Brief description of drawings]

FIG. 1 is an explanatory view of an optical disc to which the present invention is applied, and FIG.
The figure is an explanatory view showing a method for manufacturing the optical disc of FIG. 1 ... Transparent substrate 2 ... Underlayer 3 ... Recording metal film 4 ... Enclosure 5 ... Metal stamper

Front page continuation (72) Ryoichi Sudo, Ryoichi Sudo, 292 Yoshida-cho, Totsuka-ku, Yokohama, Kanagawa, Ltd., Production Engineering Research Laboratory, Hitachi, Ltd. Central Research Center

Claims (1)

[Claims] 1. An optical disk comprising a transparent substrate, an underlying layer having irregularities corresponding to information signals provided thereon, and a recording film layer provided thereon in this order. 20-80 parts by weight of the compound represented by the general formula (1), 100 parts by weight of a mixture consisting of 80 to 20 parts by weight of the compound represented by the following general formula (2), and 100 parts by weight of this mixture is photopolymerized. An optical disk comprising an ultraviolet curable resin composition containing 0.1 to 5.0 parts by weight of an initiator, which is cured. (However, R ₁ and R ₂ are hydrogen or a methyl group, n is an integer, and n =
5-12)