JPS6066344A - Optical disc - Google Patents

Abstract

PURPOSE:To obtain an optical disc having high faithfulness at the time of transfer and completely prevented from the damage of a substrate at the time of molding by constituting the substrate of the optical disc with a glass substrate having 40kg/mm.<2> or more bending strength. CONSTITUTION:The optical disc is obtained by using the glass substrate as a supporting body, a forming liquid molding resin to curable by the action of irradiated rays and transferring a rough pattern corresponding to recording information by a reproducing metal mold. Consequently, the glass substrate having 40kg/mm.<2> or more bending force is used as the supporting body. Since heat resistance is increased, the optical disc superior in the faithfulness of transfer of the glass substrate having a fine and routh pattern and completely prevented from the damage of the substrate at the time of molding can be obtained.

Description

Detailed Description of the Invention [Technical Field of the Invention] The present invention relates to optical discs such as digital audio discs, video discs, document file discs, etc., and particularly relates to optical discs such as digital audio discs, video discs, document file discs, etc. The present invention relates to an optical disk substrate provided.

[Technical background of the invention and its problems]

Traditionally, digital audio discs, video discs,
In order to obtain optical discs such as document file discs, we use injection molding mainly made of acrylic resin or polycarbonate resin using, for example, master discs (here also referred to as stampers) with grooves and bit signals engraved on the fully curved surface. are doing.

However, in optical discs with high-density unevenness signals, such as video discs, the pits are so minute that they are often molded with a resin with high fluidity, that is, a large melt flow index (MFI value), and then Reproduces minute unevenness signals. However, on the other hand, resins with a large MFI value have the disadvantage of a low heat distortion temperature. It was impossible to satisfy the thermal deformation temperature, the reproducibility of the micro-asperity signal, and the birefringence at the same time.

On the other hand, the cell cast thermal polymerization method is also well known as a method of micro-machining signals from minute irregularities on the surface of the master. Acrylic resin and diallyl glycol biscarbonate resin (CR/3a) are mainly used, and while they have excellent performance such as high transfer accuracy of minute unevenness signals and no optical distortion such as refraction, they are difficult to use due to the polymerization of the monthly charge. The process takes a long time (5
This requires a considerable amount of time), resulting in extremely low workability and insufficient heat resistance.

Therefore, as a method for forming optical discs that improves the above-mentioned drawbacks, a photopolymer method is proposed in which an ultraviolet curable resin coating is provided on a glass plate or a cell-chast thermopolymerized plate, and a replica of the minute concavo-convex signals of the original disc is formed on this coating. The zation method is also well known. Although it does improve the poor workability, which was a problem with the injection molding method, such as the inaccurate transfer of minute unevenness signals of the stamper, optical distortion, and cell cast), which was a problem with the PS polymerization method, When cell cast thermopolymerized board is used for the substrate, heat resistance is not necessarily sufficient. On the other hand,
When a glass plate is used as the substrate, although the above-mentioned drawbacks can be improved, there are major drawbacks in the molding process. For example, a mold having a minute unevenness signal as disclosed in JP-A-53-116105, for example, an ultraviolet curable resin is provided at the center of the stamper surface, That is, a circular glass plate is pressed against the stamper, the glass plate is deformed one after another, and the glass plate is finally flattened into a love shape, and the resin is spread from the center of the stamper to the outer periphery and cured to form an optical disc. 3. When deforming into an L-shaped symmetry, or when peeling off molding [1ζ] from a stamper, the glass substrate had a major drawback in that it broke.

Furthermore, in JP-A-55-152027, a mold having minute irregularities 1, 1, and the like is used. The stamper and the substrate are moved relative to each other to compress the gap to a predetermined thickness, and in this state, radiation is irradiated and keyed to obtain an optical disk. For this reason, the glass substrate has a disadvantage in that the strength of the glass substrate is low and it is easily damaged when the mold and the molded body are separated from each other.

[Purpose of the invention]

It is an object of the present invention to provide an optical disc, such as a conventional digital audio disc, video disc, document file disc, etc., produced by the photovolimerization method using an ultraviolet curable resin. More specifically, it is an object of the present invention to provide an optical disc having a glass substrate manufactured by the photovolimerization method, which has a surface structure faithful to the moss information signal etched on the surface of the master disc, and whose performance does not deteriorate over a long period of time. The purpose is

[Summary of the invention]

The optical disc based on the present invention uses a glass substrate as a support, and uses a liquid molding resin that can be cured by the action of radiation on the support to transfer a concavo-convex pattern according to the information on the replica mold. In the optical disc made of
A glass substrate with a bending strength of 1 (7/ILJ or more is used. That is, 440i<r)/,j or more is used as a support. , Damage during molding, for example, by placing an ultraviolet curing resin in the center of the stamper surface, pressing a glass substrate that is deforming into a spherical symmetry onto this resin, and gradually deforming the glass substrate until it finally becomes flat. After deformation and damage when pushing the resin from the center to the outer periphery of the stamper and curing it with radiation, the molded object is released from the mold! ll'1lf
This prevents damage when cleaning. As long as the glass substrate has a bending strength of 4.0 K r/- or more, the present invention is not limited in any way to its composition, reinforcement, and treatment methods for forming an adhesive layer.

〔Effect of the invention〕

As explained above, the present invention provides radiation t! i! 4! is used as a substrate in an optical disk in which a concavo-convex pattern corresponding to the recorded information of a replica mold is transferred using a liquid molding resin that can be cured by the action of 4! Because it uses a glass substrate with bending strength of OKq/J or more, it has sufficient heat resistance, excellent fidelity in transferring fine uneven patterns, and excellent birefringence of 10 questions or less in double pass. There is. Furthermore, it has excellent workability and has the excellent effect that no damage to the substrate occurs during molding.

[Embodiments of the invention]

It has optical properties with a refractive index of 1,506 and an Abbe number of 58.9, and a bending strength of 42.5 Kf/mA% 54 Kf/
While deforming the chemically strengthened glass substrate, which has a 1.2*m-thick RQJ optically polished surface, into a spherical shape, the glass substrate was pressed against the ultraviolet WJA (F-type resin) prepared in advance at the center of the stamper surface, and the glass substrate was deformed sequentially. (Diameter 300r3mψ
Finally, the molded body is bent from the stamper to the outer periphery (spreading the fat and curing the resin by exposing it to ultraviolet rays). The original disk was formed by peeling off. When 50 disks were formed, there were no fractures. In addition, the glass substrate was removed immediately after molding the molded product and after being left under 90% R1-I at 60°C for 20 days. In the cross-cut tape test using adhesive tape, both the adhesion of the ultraviolet diverticulosclerosing qDf lipid layer were 1.
．． 007100, that is, no peeling was observed. ゛No residue of the ultraviolet curable resin was observed on the stamper surface.Next, as a comparative example, a sample with a bending strength of 20
When an optical disk was formed in the same manner as the method of the present invention using chemically strengthened glass with a threshold of 1.2 and having the same other optical properties as K9/ma and 82 Kri/-, during molding,
That is, 50 glass substrates and 10 glass substrates were damaged during spherical deformation, and when the molded body was peeled off from the stamper, 32 glass substrates were damaged.
480 glass substrates with a bending strength of 7/- were damaged, and in the end no optical disc could be formed. 11)+71, 11, 11.7 using glass substrates with different bending strengths]:J::lj<H,i
It represents the number of glass substrates that did not break during shape 1 (bending of about 6 yen for a diameter of 800 mmψ).

[Brief explanation of the drawing]

FIG. 1 shows the relationship between the bending strength and the number of defects for the optical disk of the present invention. ! This is a J1 diagram.

Claims (1)

[Claims] In an optical disc in which a concavo-convex pattern corresponding to recorded information of a reproduction mold is transferred onto a substrate using a liquid molding resin that can be cured by the action of radiation, the substrate is 40 to 9/
An optical disc characterized by having a glass substrate having a bending strength of - or more.