JPH05258356A - Optical disc and its production - Google Patents

Abstract

PURPOSE:To enhance durability as well as to enhance the bonding strength of a hub to the substrate of an optical disc and to prevent the exfoliation of the hub by plasma-etching the faces of the hub and the substrate to be bonded. CONSTITUTION:The faces of a hub and the substrate of an optical disc to be bonded are plasma-etched. In this case, only one of the faces may be plasma- etched but both the faces are preferably plasma-etched. By this plasma etching, the bonding strength of the hub to the substrate is enhanced, the deterioration of the bonding strength is hardly caused even after the lapse of a long period of time or after use under severe conditions and the hub is hardly exfoliated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disc and a method for manufacturing the same.

[0002]

2. Description of the Related Art A disk-shaped recording medium (optical disk) on / from which information is recorded / reproduced using a light beam such as a laser beam is used to clamp the optical disk on a drive spindle when the optical disk is used in a recording / reproducing apparatus. Magnetizable metal parts called hubs are attached.

This hub is usually adhered to the substrate of the optical disk by using an ultraviolet curable adhesive or by means of ultrasonic welding.

[0004]

By the way, while the optical disk is mounted on the recording / reproducing apparatus and is repeatedly used, the hub is repeatedly subjected to tensile stress and rotational stress, and the hub is peeled off. To work. Even if the force of each peeling action is small, the peeling force acts repeatedly, and thus the limit of the adhesive force may be exceeded and the hub may peel off. Therefore, it is required that the adhesive force for adhering the hub is large and that it has durability over time.

However, a hub fixed by an ultraviolet curable adhesive or ultrasonic welding means as described above has no problem in initial adhesive force, but during repeated recording / reproduction. Peeling was observed due to deterioration of the adhesive, deterioration of the substrate, and a decrease in adhesive strength due to the intrusion of water into the bonding interface. Therefore, an object of the present invention is to provide a large bonding strength between an optical disk substrate and a hub, and to bond the optical disk substrate and a hub even after a long period of time or under severe conditions. It is to provide a technology in which the deterioration of the hub does not easily occur and the hub does not easily peel off.

[0006]

The above-mentioned object of the present invention is achieved by an optical disk having a hub, wherein the bonding surface between the hub and the substrate of the optical disk is plasma-etched. To be done. or,
A method of manufacturing an optical disc having a hub, comprising: a plasma etching process for plasma-etching a bonding surface between the hub and the substrate of the optical disc; and a bonding for bonding the hub and the substrate of the optical disc after the plasma etching process. And a method for manufacturing an optical disc.

In the above invention, it is preferable that the plasma etching process has a high frequency power of about 100 to 1000 W and a processing time of about 60 to 600 seconds. And, if the degree of plasma etching treatment is too small compared to the above conditions, the effect is not obtained so much, and conversely, if the degree of plasma etching treatment is too large beyond the above conditions, the substrate material of the optical disc tends to deteriorate. In particular, it was preferable that it was within the above range. Further, in the plasma etching treatment, it is preferable to use an inert gas such as Ne, Ar, Kr, Xe as an etching gas, and the gas pressure is 1 × 10 ⁻¹ to 1 × 10 ⁻⁴ To.
It is preferable to be carried out at rr.

Further, the plasma etching treatment is only required to be performed on the bonding surface between the hub and the substrate of the optical disc, and it may be performed on both the hub side and the optical disc substrate side. Is more preferable. Here, the plasma etching treatment improves the bonding strength between the optical disk substrate and the hub, and the bonding strength is less likely to deteriorate even after a long period of time or even under severe conditions. The reason why the hub is less likely to peel off is presumably due to the following reasons.
That is, it is considered that the plasma etching treatment removed impurities on the surface of the resin and caused active species to be expressed on the surface of the resin.

The substrate material for the optical disk of the present invention is:
Examples thereof include resin materials having excellent transparency such as polyester resin, polyolefin resin, polyamide resin, polycarbonate resin and polymethacrylic resin, and inorganic materials such as glass. When the above resin is used, the calendering method, injection molding method, injection compression molding method,
A compression molding method, a photopolymer method (2P method) and the like can be used, which is preferable.

Examples of the hub include a metal hub, a resin hub in which a magnetic material (magnetic powder) is dispersed, and an integrally molded magnetic plate and resin.
It is preferable to use a resin-made hub in which is dispersed or a hub formed by integrally molding a magnetic plate and a resin, and as the resin used in such a case, polyester resin, polyolefin resin, polyamide resin, polycarbonate resin , A resin such as polymethacrylic resin, particularly a transparent resin is preferable, and particularly, the same resin as the substrate material of the optical disk or the same type of resin is preferable.

Further, the connection between the hub and the substrate of the optical disk is
A welding means such as ultrasonic welding is used, or an ultraviolet curable adhesive is used. Examples of the ultraviolet curable adhesive include epoxy acrylate, urethane acrylate, unsaturated polyester and polyester acrylate. Etc. Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto.

[0012]

【Example】

[Example 1] 1.2 m thick molded by injection molding
m, an inner diameter of 15 mm, and an outer diameter of 130 mm, a photo-magnetization film such as TbFeCo and an organic protective film are formed on a polycarbonate optical disk substrate, and the organic protective film side is placed inside and the two are bonded by a hot-melt adhesive. Pasted together

Further, a hub was produced by integrally molding a magnetic plate and a resin made of polycarbonate. Then, the hub bonding surface of the two optical disk substrates bonded together by the hot melt adhesive and the respective parts of the hub optical disk substrate bonding surface are subjected to plasma etching processing (under an argon gas atmosphere in a plasma etching processing apparatus). , 300 W, 180 seconds), and immediately thereafter, an ultraviolet-curable urethane acrylic adhesive was applied, and both were fixed to produce an optical disc.

[Example 2] An optical disk was prepared in the same manner as in Example 1, except that the plasma etching conditions were 100 W and 600 seconds. [Example 3] The same procedure as in Example 1 was carried out except that the plasma etching conditions were set to 1000 W for 60 seconds.
An optical disc was produced.

[Comparative Example 1] A magneto-optical film and an organic protective film are formed on a polycarbonate optical disk substrate having a thickness of 1.2 mm, an inner diameter of 15 mm and an outer diameter of 130 mm formed by an injection molding method. The two sides were bonded together with the hot melt type adhesive with the side of the inside facing. In addition, a hub was produced by integrally molding a magnetic plate and a resin made of polycarbonate.

Then, a UV-curable urethane acrylic adhesive was applied to the hub bonding surface on the side of the optical disk substrate, and the hub was aligned with the adhesive to fix the two together to produce an optical disk. [Comparative Example 2] In Comparative Example 1, a hub was fixed to an optical disk substrate by ultrasonic welding instead of using an ultraviolet curable adhesive to manufacture an optical disk.

[Characteristics] Regarding the optical disk of each of the above examples,
The adhesive strength of the hub was measured using a punching tester.
In addition, the optical disk of each example has a temperature of 85 ° C. and a humidity of 85% R.V.
H. The adhesive strength of the hub was measured by using a punching tester after leaving it for 2000 hours in the above environment. Tables 1 and 2 show these results.

Table 1 Adhesive strength Example 1 Material break under a load of 46 kg Example 2 Material break under a load of 42 Kg Example 3 Material break under a load of 41 Kg Comparative Example 1 Part of material break under a load of 35 Kg Peeling Comparative Example 2 Part of the material was broken under a load of 32 kg, and the hub was peeled. Table 2 Adhesive strength after being left under high temperature and high humidity Example 1 Peeling of the hub with one member breaking under a load of 26 Kg The hub is peeled off under load with one member breakage. Example 3 The hub is peeled off with one member breakage under 24 Kg load. Comparative example 1 The hub is peeled off at the adhesive interface under a load of 15 Kg. Peeling

[0019]

[Effect] According to the present invention, the bonding strength between the substrate of the optical disk and the hub is large, and even after a long time has passed,
Further, even when used under severe conditions, the joining force between the substrate of the optical disc and the hub is less likely to deteriorate, the hub is less likely to be peeled off, and an optical disc with high durability can be obtained.

Claims (3)

[Claims] 1. An optical disk having a hub, wherein a bonding surface between the hub and the substrate of the optical disk is plasma-etched. 2. A method of manufacturing an optical disk having a hub, comprising: a plasma etching step of performing plasma etching processing on a bonding surface between the hub and the substrate of the optical disk;
A method of manufacturing an optical disk, comprising: a bonding step of bonding the hub and the substrate of the optical disk after the plasma etching processing step. 3. The plasma etching process has a high frequency power of about 100 to 1000 W and a processing time of about 60 to 600 W.
3. The method for manufacturing an optical disk according to claim 2, wherein the second is the second.