JPS59168946A - Optical disc - Google Patents

Abstract

PURPOSE:To prevent the damage and to hold a print characteristic and to obtain an optical disc of less warp by forming a cross-linkable high polymer hardened thin film on the upper face of a resin substrate on the die opposite to a metallic thin film face and specifying the thickness of this hardened thin film for the thickness of a high polymer film which protects metals. CONSTITUTION:A metallic thin film 2 is formed on a rugged signal of an injection-molded resin substrate 1 by sputtering, and a metal protecting high polymer film 4 having a thickness (d) is formed on the thin film 2, and various kinds of print are provided on the film 4, and a cross-linkable high polymer hardened thin film 5 is formed on the reading side of the signal of the resin substrate. With respect to this cross-linkable high polymer hardened thin film 5, acrylic coating materials or silicone coating materials which are hardened with ultraviolet rays are used, and its thickness (t) is set to satisfy 1/10<=t/d<=4/5. Thus, the print characteristic on the rear face is held, and a damage preventing film is formed, and the optical disc of less warp is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an optical disc that is applied to a digital signal processing disc using light, such as a digital audio disc.

Structure of conventional example and its problems Conventional digital audio disc (hereinafter referred to as DM D2 base)
(all omitted) is to form a concavo-convex signal on a resin substrate of a certain thickness by injection molding or photopolymer, and then to form a thin metal film for light reflection by vapor deposition or sputtering on top of it, and then a resin to protect it on the thin metal film. A substrate or a polymer protective film is applied,
By printing thereon, the desired DAD was obtained. However, the inventors believe that if this is done alone, the resin surface will be damaged even though the DAD performs non-contact signal processing, which not only causes erroneous signal discrimination, but also reduces the product value. I discovered that. Further, when a crosslinked polymer cured thin film is formed on both sides, the problem of scratches is eliminated, but there is a problem in that the printing characteristics on the metal thin film surface are slightly inferior.

Purpose of the Invention The present invention aims to prevent scratches on optical discs and maintain the printing characteristics on the back surface of the disc, and to obtain optical discs with less warpage similar to the case where hard coating is applied to both sides. The film thickness was set to the optimum film thickness, and the optimum shape of the optical disc was found.

3-Base Structure of the Invention The present invention provides a resin substrate having an uneven surface, a metal thin film formed on the uneven surface, a polymer film that protects this metal thin film, and a cross-linked resin substrate on the upper surface of the resin substrate opposite to the surface of the metal thin film. An optical disc on which a cured polymer thin film is formed, in particular, the crosslinked polymer thin film is formed from either an ultraviolet curable acrylic coating material or a silicone coating material,
It is characterized in that the thickness of the film is 10% to 10% of the thickness of the polymer film that protects the metal, and it can be printed with less warpage.

DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of the present invention will be specifically described. FIG. 1 shows a conventional optical disc, in which aluminum 2 is sputtered onto a polycarbonate injection-molded disc 1 having uneven signals, and the signals are read from the top surface of the polycarbonate using a laser beam. Here, since aluminum, which is a thin metal film, is easily damaged and corroded, it needs protection, and a protective polymer 3 is formed thereon. Various types of printing, such as song titles and manufacturer names, are also printed on the protective polymer. FIG. 2 shows an enlarged partial sectional view of section A in FIG. 1.

As shown in FIG. 3, the present invention provides an injection molded resin substrate 1.
A metal thin film 2 is formed by sputtering on the uneven signal, and a metal protective polymer film 4 with a film thickness d is applied thereon. Various types of printing are performed on this, and the signal reading side of the resin substrate is formed. A crosslinked polymer cured thin film having a thickness t is formed on the substrate. This cross-linked polymer cured thin film may be of any material as long as it has a high surface hardness and good adhesion, but it is particularly suitable for ultraviolet curing acrylic coating materials that have a short curing speed and silicone coating materials (such as Goldch-M
ZWO149, ZWOsoo, ZWO4so manufactured by idt
) is most suitable, and examples of acrylate-based materials include materials manufactured by Mitsubishi Rayon and U L-3026 manufactured by Dainippon Ink (Unidic x-115). The material composition shown is optimal.

5/,゛6 Hepa Furthermore, 0.1 to 10 wt% of a commercially available photosensitizer can be added to the above composition, and in the above Example 1゜2, a solvent such as alcohol or toluene may be added. It is possible to add as appropriate.

In addition, the polymer film for metal protection may be of any material as long as it has low moisture permeability and good adhesion to aluminum, such as urethane acrylate, acrylate with a phosphate group, oligoester furylate, epoxy acrylate, etc. A curable coating material is optimal, and the cured film thickness d is optimally from 6μ to 25μ. In addition, as for the coating method on the disk, it can be obtained by applying the coating from both sides with a dispenser while rotating the disk vertically, leveling, drying with a spinner, and curing with ultraviolet rays. If the thickness t is ≦t/d≦% compared to the metal protective polymer film thickness d, then
It is also possible to obtain an optical disk with less warpage by coating one side at a time. When the film thickness t is smaller than 'An, the protective film is thick and warps often occur on the protective film side. Moreover, when the film thickness t becomes larger than 7%, the optical disc warps due to the crosslinked polymer cured thin film because the crosslinked film is harder.

Another attempt was made to treat both sides of the cross-linked cured thin film, but although this was very effective in terms of warping, it also had the disadvantage that the cross-linking density was high and the UV-curable printed characters on the metal thin film side were likely to peel off. The structure of the present invention is also excellent in printability.

Effects of the Invention The present invention maintains the printing characteristics on the back side of an optical disk, and also forms a scratch-preventing film by applying a hard coating (cured cross-linked polymer thin film) to the signal reading side surface. By controlling the thickness of the crosslinked polymer thin film to a predetermined ratio to the thickness of the metal protective polymer film, it has great industrial value in that it is possible to provide optical discs with less damage.

Note that if the thickness of the polymer film that protects the metal thin film is the same as the thickness of the crosslinked polymer cured thin film, the crosslinked polymer will be harder than the former, so even if the same curing is performed while rotating, , soshi occurs. Furthermore, if the crosslinked polymer thin film is less than 1 μm, it will be affected by the hardness of the resin substrate and will not play the role of a cured film. Therefore, it is necessary to form the polymer film thickness that protects the metal to be 4A to 10 times the thickness of the crosslinked polymer thin film. When it is 10 times or more, the warpage of the disk becomes large.

[Brief explanation of the drawing]

1 is a half-sectional view of a conventional optical disc, FIG. 2 is a partial sectional view of section A in FIG. 1, FIG. 3 is a half-sectional view of an optical disc according to an embodiment of the present invention, and FIG. It is a partial sectional view of B part. 1...Resin substrate with uneven signals, 4...
... Polymer film for metal protection, 6... Crosslinked polymer cured thin film (hard coat film). Name of agent: Patent attorney Toshio Nakao and one other doctor 25/Deaf

Claims (1)

[Claims] (1) A resin substrate having an uneven signal, a metal thin film applied on the uneven signal, a polymer film that protects this metal thin film, and a crosslink formed on the upper surface of the resin substrate opposite to the metal thin film surface. a cured polymer thin film, the crosslinked polymer cured thin film is formed from either an ultraviolet curable acrylic coating material or a silicone coating material,
The film thickness is 4/6 to 1/4 of the polymer film thickness that protects the metal.
/1o optical disc.