JPH04344343A - Optical disk - Google Patents

Abstract

PURPOSE:To provide the optical disk which is improved in the mechanical strength of a protective layer, has the high property to protect recording layers and does not allow the splashing of splinters even in the event of the cracking of the disk. CONSTITUTION:This optical disk has at least the recording layers 2 on a substrate 1 and is constituted by providing a protective film 4 via an adhesive layer 3 on the recording layers 2.

Description

[Detailed description of the invention]

0001

[Industrial Field of Application] The present invention relates to optical discs, and more specifically, the mechanical strength of the protective layer is improved, the recording layer is highly protected, and even if the disc is broken, it will not be broken into pieces. This invention relates to an optical disc that does not scatter.

0002

BACKGROUND OF THE INVENTION Conventionally, in optical discs having a recording layer on a substrate, problems such as scratching or corrosion of the recording layer when the recording layer is exposed have been prevented from occurring. For this purpose, a resin protective layer was formed on the recording layer. This resin protective layer has generally been formed by applying a resin such as an ultraviolet curable resin onto the recording layer by spin coating.

0003

[Problems to be Solved by the Invention] However, the resin protective layer in conventional optical discs is generally formed by applying a low-viscosity resin protective layer coating liquid onto the recording layer by a spin coating method and hardening it. Therefore, the thickness was small, and the resin contained in the resin protective layer coating solution was hard, so the mechanical strength of the resin protective layer was not sufficient. Therefore, an optical disc having such a resin protective layer,
For example, when the optical disk is loaded into a cartridge and used, if the edge of the optical disk rubs against the cartridge, there is a problem in that the resin protective layer partially peels off and the recording layer is easily exposed.

[0004] Furthermore, when the substrate is made of glass, for example, if the substrate breaks, the resin protective layer also breaks at the same time, so there is a problem in that it is impossible to prevent the fragments from scattering. The present invention has been made based on the above circumstances, and an object of the present invention is to improve the mechanical strength of the protective layer, to provide high protection for the recording layer, and to prevent the disc from cracking. Another object of the present invention is to provide an optical disc that is resistant to scattering of fragments.

[0005]

[Means for Solving the Problems] The gist of the present invention to achieve the above object is to provide an optical disc having at least a recording layer on a substrate, in which a protective film layer is provided on the recording layer via an adhesive layer. This is an optical disc characterized by:

[0006]

[Operation] In the optical disc of the present invention, a protective film layer is provided on the recording layer formed on the substrate via an adhesive layer. Here, unlike conventional protective layers, the protective film layer is not coated but is in the form of a film, so the material and thickness can be determined as desired. Therefore, the thickness can be increased compared to conventional protective layers, and sufficient mechanical strength is ensured. Furthermore, since this protective film layer has higher breaking strength than conventional protective layers, it will not break even if the substrate is broken. Therefore, even if the substrate is broken, the fragments are adhered to the protective film layer via the adhesive layer, so the fragments will not be scattered.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a perspective sectional view schematically showing an optical recording disk of the present invention. As shown in FIG. 1, in this optical recording disk, a protective film layer 4 is formed on a recording layer 2 provided on one side of a light-transmitting substrate 1 via an adhesive layer 3.

The material for forming the substrate 1 may be any material as long as it has light transmittance, such as resins such as polycarbonate (PC), polymethyl methacrylate (PMMA), and optical glass. Particularly in the case of glass, the effect of preventing scattering of fragments according to the present invention is remarkable. The recording layer 2 provided on one side of the substrate 1 is made of, for example, TbFe.
, TbFeCo, GdCo, GdTbFe, MnCuB
Magneto-optical recording materials such as i; optical recording materials with pit formation such as Te-based materials, As-Te-Ge-based materials, Sn-
It is formed from various optically recordable materials, such as phase change optical recording materials such as Te-Se based materials.

[0009] The recording layer 2 may be formed directly on the substrate 1, or may be formed using a suitable intermediate layer having light transmittance, such as a transfer layer (not shown) having grooves made of ultraviolet curable resin. It may be formed through layers. On the recording layer 2 formed on one side of the substrate 1, an adhesive layer 3 is formed on the entire surface or a part of the recording layer 2.

The adhesive layer 3 is made of, for example, diazoresin obtained by condensing an aromatic diazonium salt with formaldehyde, or an aromatic diazonium salt-based photosensitive resin obtained by combining this diazoresin with poval, phenol resin, etc.; for example, silicone. Photodimeric photosensitive resins made by introducing dermal acid groups into the side chains of linear polymers such as poval and acrylic resins; unsaturated polyesters, epoxy acrylates,
Photopolymerizable photosensitive resins such as photoradical polymerizable resin compositions prepared by adding prepolymers such as urethane acrylate or poval, polyamide, polymethacrylate, etc. as binder polymers, various acrylate or methacrylate monomers, and photopolymerization initiators, etc. UV-curable so-called 2P (photopolymerization: Pho
to-Polymerization) adhesives, etc.

The protective film layer 4 attached to the recording layer 2 via the adhesive layer 3 has mechanical properties, chemical resistance, water resistance,
It is desirable that the film has excellent properties such as oil resistance, solvent resistance, abrasion resistance, and aging resistance, such as polyethylene terephthalate (PET) film, polycarbonate (PC) film, polyamide resin film, acetate film, polypropylene film, It is formed from polyurethane film, etc.

The thickness of the protective film layer 4 cannot be uniformly determined because it varies depending on the material for forming the film layer, the material of the substrate 1, etc., but it is usually about 10 to 100 μm. This protective film layer 4 may be provided so as to cover the entire surface of the recording layer 2, for example, as shown in FIG. 1, or when the recording layer 2 has relatively excellent moisture resistance, corrosion resistance, etc. may be provided so as to cover the peripheral edge of the recording layer 2, as shown in FIG. For example, Figure 2
When the protective film layer 4 is provided to cover the peripheral edge of the recording layer 2 as shown in FIG.
Moreover, cracking of the substrate 1 can be prevented. Furthermore, the protective film layer 4 may be provided on the adhesive layer 3 formed on the peripheral edge of a suitable resin protective film (not shown) coated on the entire surface of the recording layer 2.

[0013]

[Effects of the Invention] According to the present invention, with the above structure, the mechanical strength of the protective layer is improved and the recording layer is highly protected, and even if the disc breaks, To provide an optical disc that does not have scattered fragments.

[Brief explanation of drawings]

FIG. 1 is a schematic cross-sectional perspective view showing an example of an optical disc of the present invention.

FIG. 2 is a cross-sectional view schematically showing another example of the optical disc of the present invention.

[Explanation of symbols]

1...Substrate 2...Recording layer 3...Adhesive layer 4...Protective film layer

Claims (1)

[Claims] 1. An optical disc having at least a recording layer on a substrate, characterized in that a protective film layer is provided on the recording layer via an adhesive layer.