JPH0732036Y2 - Mold for laminating optical disks - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a mold used for coating video disks, optical disks, etc. and bonding them over the entire surface.

(Problems of the prior art) Conventionally, as a method of applying an adhesive to two surfaces of a video disk and an optical disk and bonding them over the entire surface, there are a method of sticking the two into a roll and a method of pressure bonding using a press. There is a general method of pressure bonding using a press in order to suppress deformation such as warpage of the bonded disk substrates to a small extent. Usually, when pasted together using a press, air bubbles easily enter the adhesive layer. In order to prevent this, a method of bonding and pressing in a vacuum system, returning to atmospheric pressure and removing (JP-A-63-144440), or applying an adhesive linearly in the circumferential direction on the inner peripheral part of the substrate The adhesive layer is spread over the inner and outer circumferences after being placed and bonded together, or the disc substrates coated with an adhesive are bent to make two substrates point-bonded (or line-bonded) and gradually bond the substrates. A method of gradually expanding the bonded portion from the point (Japanese Patent Laid-Open No. 63-4942).
4) and other methods have been proposed to prevent the inclusion of air bubbles. However, these methods have various problems in the following points.

(Problems to be solved by the invention) When air bubbles are mixed in the adhesive layer of the whole surface bonded optical disc, a cycle test is performed under the environmental conditions of high temperature of 80 ° C, 85% relative humidity and high humidity to low temperature of -20 ° C. Due to the deformation of the substrate, the warp angle and the surface tension become large, which deviates from the standard value. In addition, air bubbles are transferred to the recording layer or the reflective layer to deteriorate recording characteristics, which is not preferable.

In order to prevent the inclusion of air bubbles, the method of bonding and pressing in a vacuum system, returning to atmospheric pressure and taking out the substrate requires special equipment, and the productivity is low. In addition, a method in which the adhesive is linearly applied in the circumferential direction on the inner peripheral portion of the substrate, and the adhesive layer is spread to the inner and outer peripheral portions after being bonded is It is not preferable because the adhesive may not be applied enough to coat the inner and outer peripheral edges. Further, when the adhesive is a hot-melt resin, it is difficult to use because the hot-melt resin cools and does not spread from the inner peripheral portion. On the other hand, the method of bending the substrates coated with the adhesive to make the two substrates point-bonded (or line-bonded), and gradually spreading the bonded portions of the substrates sequentially from the bonding point is simple. Although visible, it is difficult to make a bonded substrate with little deformation.

An object of the present invention is to provide an optical disk bonding die in which deformation of a bonded substrate is small with a simple facility, there is no excess or deficiency of the adhesive, and bubbles are not mixed in the adhesive layer.

(Means for Solving the Problems) A recording layer and / or a recording layer is formed on one surface of the plastic substrate of the present invention.
Alternatively, in an optical disk laminating die, two optical disk substrates having a reflective layer are coated with an adhesive so that the recording layers or the reflective layers face each other and are bonded to each other. The present invention relates to a mold for laminating an optical disk, which is curved and has a rubber-like elastic body that is convexly curved on the mold surface.

(Operation and Examples) FIG. 1 shows a schematic sectional view of the optical disk bonding die of the present invention. For example, the optical disk substrate used for bonding is made of polycarbonate and has an outer diameter of 130 mm and an inner diameter of 15 m.
In the case where two optical disk substrates each having a thickness of 1.2 mm and a recording layer and an organic protective layer formed on one surface are coated with an adhesive so that the recording layers face each other and bonded, The upper and lower molds 1, 1'have a diameter of 150 mm and a thickness of 15 mm,
The bonding surfaces 2 and 2 ′ have a diameter of 130 mm and are concavely curved. The dimension of the curved surface of the mold is determined by computer simulation calculation if the dimension of the curved surface of the rubber-like elastic body 3, 3'formed convexly on it and the elastic modulus and the clamping pressure are known. You can The mold clamping pressure is arbitrarily determined depending on the kind and viscosity of the adhesive and the film thickness of the adhesive layer, but usually 50 to 500 Kg / cm ² is suitable.

A column 4 for centering and fixing is provided in the center of the lower mold of the present invention, and a hole 5 through which the column is inserted is provided in the upper mold. Insert the optical disk substrate coated with the adhesive into the cylinder of the lower mold with the adhesive side facing up, then fit the other substrate into the cylinder and press gently until the specified pressure is reached. Since the pressure is applied horizontally evenly, an optical disk can be obtained in which the thickness of the adhesive layer is uniform and the deformation of the substrate such as warpage or surface wobbling is small, and which is bonded over the entire surface.

As a comparative example, in the case of a conventional mold as shown in FIG. 2, when the bonding surface of the mold remains flat and a rubber-like elastic body is convexly curved thereon to form a bonded optical disk substrate, The thickness of the inner peripheral portion of the adhesive layer was thin and the thickness of the outer peripheral portion was thick, so that the substrate was warped and deformed in a concave shape with respect to recording and reproducing light rays.

As another comparative example, in a conventional mold as shown in FIG. 3, the bonding surface of the mold remains flat, and a rubber-like elastic body is provided on it with a certain thickness, and a convex shape is further formed thereon. When it was formed by bending, the bonded optical disk substrates were deformed, and the surface wobbling was particularly large.

(Effect) The optical disk bonding mold of the present invention, which is used for bonding, has a pair of upper and lower mold surfaces that are concavely curved, and a rubber elastic body that is convexly curved is formed on the mold surfaces. When the entire surface of the optical disc is pasted using, the adhesive layer does not contain air bubbles, the thickness of the adhesive layer is uniform, and there is little deformation such as substrate warpage or surface wobbling Also has a very good effect.

[Brief description of drawings]

FIG. 1 is a schematic sectional view of an optical disk laminating die of the present invention, and FIGS. 2 and 3 are schematic sectional views of a conventional optical disk laminating die as a comparative example. (Explanation of symbols) 1,1 ′. ...... Upper and lower molds 2,2 '. ...... Concave curved parts of upper and lower molds 3,3 '. …… Convex curved rubber-like elastic body formed on the bonding surface of the upper and lower dies 4. …… Centering and fixing cylinder of the bonding disk substrate 5. …… Centering and fixing cylinder insertion hole

Claims (1)

[Scope of utility model registration request] 1. An adhesive is applied to the entire surface of two optical disk substrates each having a recording layer and / or a reflective layer formed on one surface of a plastics substrate so that the recording layers or the reflective layers face each other. An optical disk bonding mold, wherein upper and lower mold surfaces of the matching optical disk bonding mold are curved in a concave shape, and a rubber-like elastic body curved in a convex shape is formed on the mold surface.