JPH07182701A - Method of manufacturing optical recording medium - Google Patents

Abstract

(57) [Summary] [Objective] An amount of change in the warp of a substrate that occurs when a material for a protective coating layer of an optical recording medium is cured by irradiation of ultraviolet rays is controlled to manufacture an optical recording medium with a small warp. [Structure] When the material of the protective coating layer 4 applied to the optical disc 1 is cured, the temperature sensor 12 and the temperature controller 13 keep the temperature at which the warp of the optical recording medium is relaxed.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for producing an optical recording medium having a protective coating layer.

[0002]

2. Description of the Related Art Generally, an optical recording medium such as an optical disk is provided with a protective coating layer for protecting the recording layer of the optical recording medium from impact, corrosion and the like. Usually, an ultraviolet curable resin is applied on the recording layer of an optical recording medium by a spin coating method, and then cured by being irradiated with ultraviolet rays. When the protective coating layer material coated on the recording film of the optical recording medium by the spin coating method is cured by irradiation with ultraviolet rays from an ultraviolet lamp, the protective coat curing device includes a light ray component other than ultraviolet rays generated from the ultraviolet lamp, particularly A heat ray cut filter is provided between the ultraviolet lamp and the optical recording medium to remove heat rays (infrared rays) and prevent the optical recording medium from being deformed due to an abnormally high temperature. Also, keep the temperature inside the curing device from rising (usually below 40 ° C).
An exhaust fan is installed in the protective coat curing device.

[0003]

When the ultraviolet curable resin, which is the material for the protective coating layer of the optical disc or the like, is cured by the irradiation of ultraviolet rays, the ultraviolet curable resin contracts, so that the warp of the substrate of the optical recording medium changes. To do. With the above-described conventional apparatus for curing the optical disk protective coat layer, it is very difficult to control the amount of change in the warp of the substrate of the optical recording medium when the protective coat layer is cured. If the warp of the optical disk becomes large due to the hardening of the material of the protective coating layer, there arises a disadvantage that a recording failure or a reproduction failure of data is likely to occur when the information is recorded / reproduced on / from the optical recording medium by the optical disk device or the like. Therefore, conventionally, it has been necessary to suppress the warp of the substrate of the optical recording medium within a certain range before applying the protective coating layer, which causes a problem that the molding conditions of the optical recording medium substrate become strict.

The present invention has been made to solve the above-mentioned problems, and controls the amount of change in the warp of the optical recording medium substrate that occurs when the material of the protective coating layer is cured by irradiation of ultraviolet rays. It is an object of the present invention to provide a method for manufacturing an optical recording medium having a small size.

[0005]

According to the method for producing an optical recording medium of the present invention which achieves the above object, when the material of the protective coating layer applied to the optical recording medium is cured, the optical recording medium is not warped. It is characterized in that the temperature is maintained at a relaxed temperature.

[0006]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic configuration diagram of a curing device for an optical disk protective coat layer used in one embodiment of the present invention.
In FIG. 1, reference numeral 1 is an optical disc, which is composed of a polycarbonate substrate 2, a recording film 3 and a protective coat layer 4. 5 is an ultraviolet lamp power source, 6 is an ultraviolet lamp, 7 is a heat ray cut filter, 8 is a disk holder, 9 is an intake port, 10 is an exhaust port, 11 is an exhaust fan, 12 is a temperature sensor, 13 is a temperature controller, 14 is It is a heater.

The operation of the apparatus for curing the optical disk protective coat layer shown in FIG. 1 will be described. The protective coat layer material (made of an ultraviolet curable resin) 4 applied on the recording film 3 of the optical disc 1 by the spin coating method is cured by irradiating it with ultraviolet rays using an ultraviolet lamp 6 to form a protective coat layer of the optical disc. To be done. The heat ray cut filter 7 is provided to remove light components other than ultraviolet rays generated from the ultraviolet lamp 6, particularly heat rays (infrared rays), and prevent the optical disc 1 from being deformed due to an abnormally high temperature. The exhaust fan 11 supplies the air taken in through the intake port 9 to the exhaust port 10
Exhaust through. The temperature controller 13 controls the electric power of the heater 14 by the output of the temperature sensor 12 provided in the curing device for the protective coat layer, and controls the temperature in the curing device so that the warp of the optical recording medium is alleviated. .

Next, a method of controlling the amount of warp of the optical disk when the protective coat layer is cured by using the above curing device will be described. In the case of an optical disc in which a recording film is formed by a sputtering method, the recording film has a compressive stress, and thus the optical disc substrate after the recording film is formed warps in the negative direction in which the recording film side is convex as shown in FIG. . When the material of the protective coat layer applied on the recording film is cured by irradiation with ultraviolet rays, the warp of the optical disc substrate changes in the positive direction of FIG. 2 due to contraction. On the other hand, the relationship between the temperature of the protective coat layer in the curing device and the warp of the cured optical disk substrate is measured in advance. An example thereof is shown in FIG. When the temperature inside the curing device is increased, the polycarbonate substrate is easily deformed, so that the amount of change in the positive direction that occurs when the material of the protective coating layer is cured by ultraviolet irradiation increases. That is, in the example shown in FIG. 3, by setting the temperature in the curing device to 90 ° C., it is possible to reduce the warp of the optical disc after the protective coat layer is cured to almost zero, and the mechanical strength of the optical disc can be reduced as compared with the conventional method. It is possible to manufacture an optical disc having excellent characteristics.

Although one embodiment of the present invention has been described above, the present invention is not limited to the above, and various modifications are possible. For example, as a heating method in the curing device, a method of reducing the air volume of the exhaust fan without using a heater, a method of reducing the heat ray cut rate of the heat ray cut filter, or the like may be used.

[0010]

As described above, according to the present invention, the temperature of the protective coating layer of the optical recording medium in the curing device is controlled to control the warp of the optical recording medium substrate after the protective coating material is cured to a desired value. Since it can be controlled, it becomes possible to manufacture an optical recording medium with small warpage. by this,
The reliability at the time of recording / reproducing information data on / from an optical recording medium by an optical disk device or the like is greatly improved.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a curing device for an optical disk protective coat layer in the present embodiment.

FIG. 2 is a cross-sectional view of an optical disc showing changes in the warp of the optical disc when the protective coat layer is cured.

FIG. 3 is a diagram showing the relationship between the temperature in the curing device and the warp of the optical disc substrate after curing of the protective coating layer according to the present embodiment.

[Explanation of symbols]

 1 Optical Disc 4 Protective Coating Layer 6 Ultraviolet Lamp 12 Temperature Sensor 13 Temperature Controller 14 Heater

Claims (1)

[Claims] 1. A method for producing an optical recording medium, which is characterized in that, when the material of the protective coating layer applied to the optical recording medium is cured, the temperature is maintained at a temperature at which the warp of the optical recording medium is relaxed.