JPH02139778A - Optical recording medium - Google Patents

Abstract

PURPOSE:To improve adhesive force between a disk body and a rotary shaft engaging member for correcting eccentricity by sticking the disk body to the engaging member with an adhesive into which fine particles are mixed. CONSTITUTION:A recording layer 6 capable of optically recording/reproducing information is formed on the face of a base 1 on which a tracking guide 3 is formed and stuck to a backing base 8 through an adhesive 7. A hub 4 to be an eccentricity correcting rotary shaft engaging member made of resin in which a metallic plate 9 is embedded is stuck to the center part of the base 1 of an optical recording medium with an adhesive 5. At that time, spherical beads 10 made of glass are mixed into the adhesive 5. Consequently, the layer of the adhesive 5 can be guaranteed to suppress the drop of adhesive strength due to a thin layer and the adhesive strength between the base 1 and the hub 4 can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application 1] The present invention relates to an optical recording medium on which recording, reproduction, erasing, etc. can be performed using a light beam.

[Prior Art] Conventionally, 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 substrate on which a tracking guide (guide groove) is formed. Optical recording media are known.

As shown in FIG. 2, the conventional optical recording medium has a donut-shaped hub 4 having an inner diameter smaller than the center hole 2 of the substrate 1 in order to correct the eccentricity of the center hole 2 of the substrate 1 and the tracking guide 3. It was fixed to the surface of the substrate 1 with adhesive 5.

As is clear from the figure, because the adhesive area between the disk body and the hub 4 is small, there is a problem in that the adhesive part is likely to peel off when the disk receives an impact or is stored in a high temperature, high humidity environment. .

In particular, when glass is used for the disk body and plastic such as polycarbonate or epoxy resin is used for the hub 4, the adhesive portion tends to peel off because the thermal expansion coefficient and hygroscopic expansion coefficient differ between the disk body and the adhesive.

For this reason, adhesive 5 having viscoelastic properties is used to absorb expansion and contraction due to impact force and differences in expansion coefficients between different materials.

[Problems to be Solved by the Invention] However, if the hub 4 is warped or deformed as shown in FIG. There was a problem in that a buffering effect to absorb expansion and contraction of the disk body and the hub 4 due to changes could not be obtained, and peeling was likely to occur.

The present invention was made in view of the above-mentioned problems, and
The purpose of this is to allow the circle formed by the tracking guide to rotate without eccentricity when rotated by a recording/playback device, which allows for accurate recording and playback, as well as improving the adhesion between the disc body and the hub. The objective is to provide optical recording media.

(Means for Solving the Problems) In the optical recording medium of the present invention that can achieve the above-mentioned object, a rotating shaft fitting member (hub) for eccentricity correction is attached to the center of a disk body having a recording layer with an adhesive. The optical recording medium is characterized in that the adhesive contains fine particles.

Hereinafter, embodiments of the present invention will be shown and explained in detail.

FIG. 1 is a schematic cross-sectional view of an optical disc that is one embodiment of the present invention. In FIG. 1, l is a glass substrate, on which a tracking guide 3 is formed by the 2p method. This board 1
A recording layer 6 that can be optically recorded and reproduced is formed on the surface on which the tracking guide 3 is formed, and is bonded to a backing substrate 8 with an adhesive 7.

A hub 4 made of resin with a metal plate 9 embedded therein is adhered to the center of the substrate 1 of this optical recording medium with an adhesive 5.

As shown in the partially enlarged view in FIG. 1, glass spherical beads 1o are mixed into the adhesive 5.

The beads 10 prevent the adhesive 5 from becoming too thin and unable to exert its adhesive force, and improve the adhesion between the substrate 1 and the hub 4. The diameter of the bead 10 may be selected as appropriate, but if the disk body is of a size that is commonly used, it is preferably about 50 μm or more (see Examples). However, if it becomes too large, Since the adhesion strength is weakened, it is preferably about 500 gm or less.

In this embodiment, spherical glass beads are used as the fine particles, but the material is not particularly limited as long as it does not easily deform or break, and various plastics, ceramics, etc. can be used. In addition, the shape does not necessarily have to be round in cross section; when used as a spacer, it can be shaped to prevent uneven thickness of the adhesive layer (equilateral triangle, hexagon, hexagon, etc.).
It may be rod-shaped or fibrous II).

In the present invention, there is no particular restriction on the materials of the recording layer and the substrate, and for example, polycarbonate, acrylic, epoxy resin, etc. can be used for the substrate.

【Example〕

Example 1.2 The optical recording medium shown in FIG. 1 was produced. The sizes and materials are as follows.

Substrate: Inner diameter 15mmφ, outer diameter 130mmφ Polycarbonate backing substrate 2 Same as above Adhesive Niacrylic UV curing adhesive Spherical beads:
Diameter 50μ, 100311m Silica glass adhesive/spherical beads (volume ratio) = 20:1 Metal plate: Inner diameter 4mmφ Stainless steel hub: Outer diameter 25
mmφ Polycarbonate Comparative Example 1 An optical recording medium was produced in the same manner as in the example except that spherical beads were not used.

(Evaluation) The product was left in an environment of 80° C. and 90% RH for 2000 hours, and the presence or absence of peeling of the hub was examined. The results are shown in the table below.

[Advantageous Effects of the Invention 1] As explained in detail above, in the optical recording medium according to the present invention, the disk body and the rotating shaft fitting member for correcting eccentricity are fixed using an adhesive containing fine particles. This prevents the adhesive layer between the disk body and the member from becoming too thin, and improves the adhesion between them.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view of one embodiment of the optical recording medium of the present invention,
FIG. 2 is a schematic cross-sectional view of a conventional optical recording medium, and FIG. 3 is a partial schematic cross-sectional view of the conventional optical recording medium. Substrate 2: Center hole Figure 3 Tracking guide 5.7: Adhesive 8: Backing substrate 10: Microparticle material 4: Hub 6: Recording layer 9: Metal plate

Claims (1)

[Claims] 1) An optical recording medium in which a rotating shaft fitting member for eccentricity correction is fixed to the center of a disk body having a recording layer with an adhesive, the adhesive containing fine particles. An optical recording medium characterized in that it is mixed with. 2) The optical recording medium according to claim 1, wherein the minute member has a circular cross section and a diameter of 50 micrometers or more.