JP2668305B2 - optical disk - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disk, and more particularly, to an optical disk in which a magnetic metal hub is bonded to the center of a disk substrate by an adhesive.

[0002]

2. Description of the Related Art As shown in FIG.
An annular disk substrate 1 having a circular opening 1a in the center,
And a cup-shaped hub 2 inserted and installed in the opening 1a of the disc substrate 1. The optical disk D and the hub 2 are formed by interposing an adhesive layer 5 between a flat annular flange 4 provided around the opening 3 of the hub 2 and the mounting surface 1b of the disk substrate 1. Have been. As such an adhesive, a two-liquid mixed adhesive, a thermosetting epoxy adhesive, or the like has been used.

Japanese Patent Application Laid-Open No. 2-306485 discloses that two kinds of adhesive layers are provided between an optical disk substrate and a magnetic metal hub in order to improve the bonding strength between the optical disk substrate and the magnetic metal hub. A method of intervening is disclosed.

[0004]

However, conventionally,
The above-mentioned two-component adhesive or thermosetting epoxy adhesive used for joining the optical disk substrate and the magnetic metal hub has a problem that it takes time to cure.

When two kinds of adhesive layers are used as disclosed in Japanese Patent Laid-Open No. 306485/1990, the bonding strength between the optical disk substrate and the magnetic metal hub is certainly improved. A process of applying different kinds of adhesives is required, and there is a problem in workability as compared with the case where only one kind of adhesive is used.

In addition, an acrylic or epoxy UV-curing resin is known as an adhesive used for joining an optical disk substrate and a magnetic metal hub, and it is easy to join it as shown in FIG. Although there is an advantage that bonding can be performed quickly and in a short time and workability is good, there is a problem that the essential bonding strength is not sufficient.

Further, hot-melt adhesives are known, but this adhesive has a problem that setting of coating conditions such as temperature setting is not easy as compared with other adhesives.

In order to obtain sufficient adhesion between the disk substrate and the magnetic metal hub, in addition to the above-described problems of the adhesive itself, the amount of the adhesive has a great influence. However, when joining the disk substrate and the magnetic metal hub, some pressure is applied, so that it is necessary to optimize the amount of adhesive applied. In this case, the application amount is reduced.

Therefore, the object of the present invention is that the disk substrate and the magnetic metal hub can be bonded to each other easily and in a short time as compared with the conventional optical disk, and the bonding strength is high, and the workability is excellent, and the finished product is completed. An object of the present invention is to provide a good-looking optical disk.

[0010]

Such an object is achieved by the present invention of the following (1) to (3). (1) At least one of the disc substrate and the magnetic metal hub is provided with an adhesive accommodating space, and the magnetic metal hub is joined to the disc substrate by an adhesive accommodated in the adhesive accommodating space. The agent is an ultraviolet curable resin adhesive, the hardness after curing of the ultraviolet curable resin adhesive is less than 50 at Shore D (25 ° C), and the tensile strength in a tensile strength test based on JIS dumbbell is 20 kg.
An optical disk having an f / cm ² or more and an adhesive layer accommodated in the adhesive accommodating space having a thickness of 100 μm to 200 μm.

(2) The optical disk according to (1), wherein the adhesive accommodating space is an annular groove formed in the disk substrate.

(3) The optical disk according to (1) or (2), wherein the adhesive accommodating space is an annular gutter-like portion formed by a flange formed around an opening of the magnetic metal hub.

[0013]

According to the present invention, the adhesive accommodating space provided in the disk substrate and the magnetic metal hub functions as a regulating portion for easily and optimally controlling the thickness of the adhesive layer. As a result, for example, when an ultraviolet curable resin adhesive having a fast curing time and good workability is used as the adhesive layer, the maximum bonding strength of the adhesive can be obtained.

The depth of the adhesive accommodating space, that is, the thickness of the adhesive layer accommodated therein is set so that the bonding strength of the adhesive between the disk substrate and the magnetic metal hub is maximized. The value is somewhat affected by the type of adhesive layer used, but is preferably 100 μm or more,
More preferably, it is in the range of 100 to 150 μm.

When the depth of the adhesive accommodating groove is less than 100 μm, sufficient bonding strength cannot be obtained even if any ultraviolet adhesive is used. On the other hand, when the depth exceeds 200 μm, the bonding strength is reduced. Not only is it unfavorable in terms of cost and workability.

The adhesive used in the present invention includes:
It is preferable to use an ultraviolet curable resin that can be easily joined in a short time and has excellent workability. Examples of such an adhesive include a urethane acrylate resin, an epoxy acrylate resin, an epoxidized oil acrylate, a polyester acrylate, a polyether acrylate, a vinyl / acryl oligomer, a polyene / thiol, a silicone acrylate, a polybutadiene acrylate, and a polystyrylethyl methacrylate. Etc., and urethane acrylate resins are particularly preferable.

The preferred physical properties of the adhesive which can be used in the present invention are such that the hardness after curing is 5 at Shore D (25 ° C.).
It is less than 0, and the tensile strength in the tensile strength test based on JIS dumbbell is 20 kgf / cm ² or more.

In the present invention, the material of the optical disk substrate itself is polycarbonate, which is conventionally known, and the magnetic metal hub is, for example, a SUS430 hub.

[0019]

Next, an optical disk according to a preferred embodiment of the present invention will be described with reference to FIGS. 1 and 2, the same parts as those of the conventional example shown in FIG. 3 are designated by the same reference numerals as those in FIG. 3 and their description is omitted.

In the optical disk shown in FIG. 1, an adhesive accommodating groove 6 which forms an adhesive accommodating space around the mounting surface 1b of the magnetic metal hub 2 and the opening 1a of the disk substrate 1 is provided in an annular shape. The cylindrical wall 6 provided around the inside of the groove 4 has a height T shifted by the thickness A of the flange 4 of the hub 2, so that when the hub is inserted and installed in the substrate 1. The surface 4a of the flange 4 is flush with the mounting surface 1b. The height T of the wall 7 directly defines the thickness of the adhesive layer 5 accommodated in the groove 6 (the reference numeral T is also used for this thickness). Then, the flange 4a is bonded to the mounting surface 1b by the adhesive layer 5 having the thickness T thus defined, and the substrate 1 and the hub 2 are bonded to each other. The flange 4 does not have to be accommodated in the groove 6.

On the other hand, in the optical disk shown in FIG. 2, the outer peripheral portion of the flange 4 of the magnetic metal hub 2 is formed as a rising portion 4b so as to form an annular gutter-like portion 10 forming an adhesive accommodating space. . The adhesive layer 5 is accommodated in the inside of the portion 10, and the disk substrate 1 and the hub 2 are joined by the layer 5 in the same manner as described above. The height of the layer 5 is the same as the rising portion 4
It is defined by the height of b.

The optical disk of the present invention includes a case where the adhesive accommodating space is provided in only one of the disk substrate 1 and the magnetic metal hub 2 and a case where the adhesive housing space is provided in both. However, in that case, it is necessary to set the sum of the heights of both spaces to an optimum value.

Experimental Example 1 The effect of the bonding strength on the depth of the adhesive accommodating groove of the optical disk according to the present invention was tested on the structure shown in FIG. When the urethane acrylate resin A was used as the adhesive layer and SUS430 was used as the magnetic metal hub, the depth of the adhesive accommodating groove, that is, the bonding strength when the adhesive layer thickness was 10 μm and 200 μm was measured. ,
Each was 8kgf / cm ² and 200kgf / cm ^2.

Experimental Example 2 An adhesive layer having a thickness of 10 μm and a thickness of 2 μm were prepared in the same manner as in Experimental Example 1 except that epoxy acrylate resin C was used as the adhesive layer.
The bonding strength in the case of 00μm was measured and found to be respectively 5 kgf / cm ² and 7 kgf / cm ^2.

Next, how the strength of each material and the value of the adhesive force at the interface when the hub of SUS430 and the polycarbonate substrate are joined with an adhesive are influenced by the physical properties of the adhesive. Observed.

Experimental Example 3 The hardness after curing was 40 at Shore D (25 ° C.), and the tensile strength in a tensile strength test based on JIS dumbbell was 7
The urethane acrylate resin adhesive A having a pressure of 0 kgf / cm ² or more can provide a bonding strength of more than 25 kgf / cm ² to both the SUS430 hub and the polycarbonate substrate when the thickness of the adhesive layer is about 100 μm. During the peeling test, the polycarbonate substrate was broken.

In addition, the results of the thermal shock test, which usually causes a problem in joining the SUS430 hub and the polycarbonate substrate, were also good.

Experimental Example 4 The hardness after curing was 50 at Shore D (25 ° C.), and the tensile strength in the tensile strength test based on JIS dumbbell was 1
The urethane acrylate resin adhesive B of 20 kgf / cm ² or more saturates the adhesive force between the hub of SUS430 and the polycarbonate substrate when the thickness of the adhesive layer is about 150 μm, and 25 kgf for the polycarbonate substrate.
A bonding strength of over / cm ² was obtained. But SUS
Since the adhesive force at the interface of the 430 with the hub was smaller than that of the other, it peeled off at the interface with the SUS430 at the time of the peeling test.

Experimental Example 5 Epoxy acrylate resin adhesive C as adhesive layer
(Shore D hardness 70, tensile strength 200kgf / cm
^{When 2} ) is used, the thickness of the adhesive layer is 300 μm
Even if it is thick enough, the adhesion to the SUS430 hub is 1
It was 0 kgf / cm ² or less.

[0030]

As described above, in the optical disk of the present invention, the magnetic metal hub mounting surface of the disk substrate and / or the magnetic metal hub is provided with the adhesive containing groove, and the adhesive containing groove is provided with the adhesive. By arranging
Compared to conventional optical discs, the disc substrate and magnetic metal hub can be joined easily and in a short time, and the joint strength is the highest value of the adhesive used, and the workability is excellent. The effect is obtained.

[Brief description of the drawings]

FIG. 1 is a partial sectional view of an optical disc according to a preferred embodiment of the present invention.

FIG. 2 is a partial cross-sectional view of an optical disc of another preferred example of the present invention.

FIG. 3 is a partial sectional view of a conventional optical disk.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Disc board 2 Magnetic metal hub 4 Flange 5 Adhesive layer 6 Adhesive accommodation groove 10 Annular gutter-shaped part

Claims (3)

(57) [Claims] An adhesive accommodating space is provided in at least one of the disk substrate and the magnetic metal hub, and the magnetic metal hub is joined to the disk substrate by an adhesive accommodated in the adhesive accommodating space. The adhesive is an ultraviolet curable resin adhesive, and the hardness after curing of the ultraviolet curable resin adhesive is Shore D.
It is less than 50 at (25 ° C.), the tensile strength in a tensile strength test based on JIS dumbbell is 20 kgf / cm ² or more, and the thickness of the adhesive layer accommodated in the adhesive accommodation space is 10
An optical disc having a size of 0 μm to 200 μm. 2. The optical disc according to claim 1, wherein the adhesive accommodating space is an annular groove formed in a disc substrate. 3. The optical disk according to claim 1, wherein the adhesive accommodating space is an annular gutter-like portion formed by a flange formed around an opening of the magnetic metal hub.