JPH02162547A - Production of optical disk - Google Patents

Abstract

PURPOSE:To prevent a substrate from curving and a surface treated film from cracking by subjecting the substrate surface on the opposite side of the optical disk substrate prior to formation of a recording film, reflecting film, etc., to a surface treatment with an active ray curing type resin. CONSTITUTION:An epoxy acrylate moistureproof layer 5 of a UV curing type is applied on the surface of the substrate 1 in the state of only the substrate 1 prior to provision of the recording film 2 and the reflecting film 3. The polycarbonate substrate 1 subjected to curing with UV rays has no curving and if the recording film 2 is provided thereafter on the groove surface of the substrate 1, the recording medium subjected to the moistureproofing and surface treating in the state of having no warpage is obtd. The surface hardened film 6 does not crack if the surface cured film 6 consisting of the silicon system is provided in the state of only the substrate 1 prior to provision of the aluminum reflecting film 3. The compact disk subjected to the surface hardening treatment on the substrate surface is obtd. if the guide groove side of the polycarbonate substrate 1 written with signals is thereafter subjected to vapor deposition of aluminum.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method of manufacturing an optical disc that performs reproduction, recording, or erasing using a light beam. More specifically, the present invention relates to surface treatment methods such as moisture proofing, surface hardening, antistatic, and antireflection for plastic disk substrates.

(Conventional technology) Conventionally, acrylic resin, polycarbonate resin.

A recording medium is known in which a recording layer made of an optical memory material that utilizes magneto-optic effect, photochromism, amorphous-to-crystalline phase transition, etc. is laminated on a plastic substrate such as polyolefin resin. Such recording media can be used as a single plate as is, or have an air sandwich structure in which a spacer is sandwiched between two recording media and the recording layers are bonded together so that they face each other, or two recording media can be used as is. Optical recording media have been proposed that have a bonded structure in which they are bonded to face each other. Optical recording media are generally donut-shaped, with a hole in the center of a plastic substrate molded by injection molding that engages with a rotating shaft, and recording and playback are performed while rotating around the rotating shaft. If dust or scratches adhere to the board surface, a signal (bit) error will occur. High temperature, high humidity (60°
C990% relative humidity) for long periods of time (1000% relative humidity).
When exposed to the plastic substrate for a long time, oxygen and water vapor enter from the surface of the plastic substrate, oxidizing the recording film and making it transparent, resulting in a decrease in recording characteristics (S/N ratio). Furthermore, when water is absorbed from the substrate surface, stress distortion occurs between the substrate and the recording film, causing the substrate to warp or cause surface wobbling, which changes the shape of the beam spot of the recording and reproducing light and deteriorates the recording characteristics. . In extreme cases, focusing and tracking may become impossible, making recording and playback impossible. Therefore, conventionally, on the surface of the substrate opposite to the recording film 2 and the reflective film of a plastic substrate, an oxygen barrier film, a moisture-proof film 2, a surface hardening film, and an antistatic film 2 are used.
Recording media having a structure provided with an antireflection film or the like have been proposed.

(Problem to be Solved by the Invention) Conventionally, after forming a recording film or a reflective film on the substrate of an optical disc, a moisture-proof film 2, a surface hardening film, and an antistatic film are applied to the surface of the substrate opposite to the recording film or reflective film. 2 surface treatment to form an anti-reflection film, etc. When the surface of the reflective side of the plastic substrate on which the reflective film of the recording film 2 is formed is subjected to the above-mentioned surface treatment, strain may occur between the substrate and the reflective film of the recording film 5 during ultraviolet curing or thermal curing during the surface treatment process, causing the substrate to deteriorate. There were many inconveniences such as deformation (increased warpage angle) and cracks in the surface hardened film.

The purpose of the present invention is to provide a method for surface treatment of plastic substrates that does not cause deformation of the substrate or cracks in the surface treatment coating due to surface treatment, and which has moisture resistance, 8 surface hardening properties, and 2 antistatic properties and 2 antireflection properties. The purpose of the present invention is to provide an excellent optical disc manufacturing method.

(Means for Solving the Problems) That is, the present invention provides a method for manufacturing optical discs in which information is reproduced, recorded, or erased using light. This is a method for manufacturing an optical disc, characterized in that a substrate surface is surface-treated with an actinic ray-curable resin. Here, the actinic rays include ultraviolet rays, infrared rays, electron beams, X-rays, or simply heat rays.

(Operations and Examples) Examples of the present invention will be described below with reference to FIGS. 1 and 2. Generally, the disk substrate 1 for optical recording media made of acrylic resin, polycarbonate resin, polyolefin resin, etc. is mass-produced by injection molding. Conventionally, a recording layer 2 is provided on a group surface of a disk substrate 1, a recording layer 3 is provided on top of that, and a recording layer 4 is further provided on top of that to form an optical recording medium, and the recording layer 2 is placed on the side opposite to the reflective layer. Moisture-proof film 52 surface hardening film 6. An antistatic film 7° and an antireflection film 8 were provided to protect the plastic substrate 1.

However, for example, when UV-curable epoxy acrylate is applied to the surface of the polycarbonate substrate 1 as the moisture-proof film 5 and UV irradiation is performed, light and thermal energy cause damage between the substrate 1 and the recording film 2 made of Gd, Tb, Fe, and Co. As a result, the polycarbonate substrate 1 is bent so that the moisture-proof film 5 side is concave. When the curvature (warp angle) of the substrate 1 exceeds 0.5 degrees, the recording and reproducing light beams are focused.

Tracking becomes impossible, making recording and playback impossible. An ultraviolet-curable epoxy acrylate moisture-proof layer 5 is applied to the surface of the substrate 1 with only the substrate 1 before the recording film 2 and reflective film 3 of the present invention are provided, and the ultraviolet-cured polycarbonate substrate 1 has no warp. Then, a recording film 2 made of Gd, Tb, Fe, and Co is deposited on the group (guide groove) side of the substrate 1 by sputtering.
By providing this, it is possible to obtain an optical recording medium in which the substrate is moisture-proofed and surface-treated without warping. In addition, a playback-only digital audio disc (compact disc) is provided with an aluminum reflective film 3 on a polycarbonate substrate 1.
A silicone-based surface hardening (hard coat) agent is applied to the surface of the substrate opposite to the reflective film 3, and cured for 5 minutes at 100'C using a far infrared ray device. Applied strain occurs between the film 3 and the surface hardened film 6, which causes cracks to occur in the surface hardened film 6. In this case as well, if the silicon-based surface hardening film 6 is provided on only the substrate before the aluminum reflective film 3 is provided, no cracks will occur in the surface hardening film 6, and after that, the guide groove side of the polycarbonate substrate 1 on which the signal has been written By performing aluminum evaporation on the substrate, a compact disc with a surface hardening (hard coat) treatment can be obtained.

(Effects of the Invention) Before the recording film 2 reflective film is formed on the plastic substrate of an optical disc, the substrate surface on the opposite side from the recording film 2 reflective film is made moisture-proof and surface hardening.

Antistatic property 9 In the method for manufacturing an optical disc of the present invention, which performs surface treatment with excellent antireflection properties, the optical disc substrate and recording material are caused by applying active light or thermal energy to the curable resin during surface treatment. Since there is no applied distortion between the film or the reflective film, the substrate will not curve or cracks will occur in the surface treatment film, and a highly reliable optical disc can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view of an optical disc showing one embodiment of the present invention. FIG. 2 is a schematic cross-sectional view of an optical disc showing another embodiment of the present invention. (Explanation of symbols) 1,... Polycarbonate disk substrate 2,... Multiple recording layers 3,... Aluminum reflective layer 4,...・・・・・・ Protective layer

Claims (1)

[Claims] In the manufacturing process of optical discs in which information is reproduced, recorded, or erased using light, the surface on the opposite side of the optical disc substrate is treated with an actinic ray-curable resin before forming a recording film, reflective film, etc. A method of manufacturing an optical disc.