JPS6369041A - Production of substrate for optical recording medium - Google Patents

Abstract

PURPOSE:To easily produce a substrate for an optical recording medium which does not contain air bubbles and has high reliability by heating a curable resin in the stage before the substrate is imposed on the curable resin and removing the air bubbles incorporated into the resin by making use of a decrease in the viscosity of the resin. CONSTITUTION:After the curable resin 1 is laminated on a mold (stamper) 2 having the ruggedness corresponding to the shape of guide grooves, the glass substrate is imposed on said resin; thereafter, the resin 1 is cured to produce the substrate for the optical recording medium having the guide grooves made of the curable resin. The curable resin 1 laminated on the mold 2 is heated by a heater 5 provided on a carrier 3 to remove the air bubbles 5 incorporated into the resin 1 in the stage before the substrate is imposed on the resin 1. The glass substrate is thereafter imposed on such resin 1 and UV rays are projected thereto to cure the resin 1. The substrate cured and integrated with the resin 1 is then parted from the mold 2 and the substrate having the guide grooves made of the curable resin is obtd.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a method of manufacturing a substrate for an optical recording medium that can perform recording and reproduction using a light beam, and in particular, a method of manufacturing a substrate for an optical recording medium that is made of a curable resin and has guide grooves. The present invention relates to a method of manufacturing a substrate for an optical recording medium.

[Prior Art] Conventionally, J and ζ plate materials for optical recording media have been used.
Glass, acrylic resin, polycarbonate resin, etc. are used. In order to perform high-density recording on an optical recording medium, it is necessary to form optical guide grooves on the root plate, and several methods are conventionally known as methods for forming the grooves.

One method is to apply a hardening resin onto a mold called a stambar, which is carved with unevenness corresponding to the shape of the guide groove, and then place a substrate on this resin. There is a method of manufacturing a substrate for an optical recording medium having a guide groove made of a curable resin by hardening the resin by irradiating light or the like to transfer the guide groove, and then fixing the resin to the substrate.

The ζ plate made by this method has excellent transferability of the guide groove shape, and has the advantage that optical distortion of the guide grooved substrate can be reduced compared to other methods. However, in addition to being inferior to other methods in terms of mass production, the following problems remained unsolved.

That is, the problem is air bubbles mixed into the resin. That is, if air bubbles are included in the curable resin laminated on the stanbar, the resin will be cured while the air bubbles are taken in when the resin is cured.

In particular, if there are air bubbles in the area that comes into contact with the stand bar,
Since that portion is cured as it is, the shape of the guide groove cannot be accurately transferred, which may cause a defect and reduce the reliability of the optical recording medium.

Such air bubbles may be mixed into the curable resin during the adjustment stage of the curable resin before laminating the resin onto the stand bar, or during the resin coating operation during lamination. Air bubbles are removed using foam.

However, it is not easy to remove air bubbles, especially when trying to remove air bubbles that get mixed into the resin during lamination, which not only requires a large vacuum device with a stand bar, but also requires a separate degassing process. This was also a cause of increased costs.

[Problems to be Solved by the Invention] The present invention has been made in view of the above-mentioned points, and provides a highly reliable optical recording system in which the above-mentioned air bubbles can be easily removed and no air bubbles are mixed into the resin. It is an object of the present invention to provide a method for manufacturing a substrate for an optical recording medium, which allows the substrate for the medium to be easily manufactured.

[Means for Solving the Problems] The above objects of the present invention are achieved by the present invention below.

After a curable resin is laminated on a mold having unevenness corresponding to the shape of the guide groove, a substrate is placed on the resin, and then the resin is cured to form an optical mold having a guide groove made of the curable resin. A method for manufacturing a substrate for an optical recording medium, which comprises heating and defoaming the curable resin before placing the substrate on the curable resin. A method for manufacturing a substrate for a recording medium.

[Function] In the method of the present invention, the resin is heated before the substrate is placed on the curable resin, and air bubbles mixed in the resin are defoamed by utilizing the decrease in the viscosity of the resin due to the heating. In order to do
It is possible to easily and quickly perform degassing, and to easily produce a highly reliable substrate for an optical recording medium in which no air bubbles are mixed into the resin.

Figure 1 is a schematic cross-sectional view illustrating an example of the defoaming process in which air bubbles taken into the resin are removed from the resin by heating. resin, and 2 is a stambar.

In this FIG. 1, heating is performed by a heater (not shown) arranged on the back side of the stand bar 2, and the hardening resin 1 of the stand bar 2, 41 before heating which incorporates air bubbles a is heated.
(See Figure 1 (8)) From inside, bubbles rise and are removed in the order of Figure 1 (B) → Figure 1 (C) due to the decrease in the viscosity of the resin 1 with the start of heating. has been done.

Heating in the present invention may be carried out after the resin is laminated on the stand bar as illustrated in FIG. This may be carried out at the step of adjusting the resin 4A of the tail portion to be laminated to the stambar or when laminating the resin to the stambar.

In the present invention, various curable resins that are cured by light, heat, etc. can be used, but the resin must have a viscosity of 60 cps or more at 25 °C and a viscosity of 150 cps or less at 100 °C. is preferred.

This is because if the viscosity of the curable resin is too low, when the board is placed on the resin on the stand bar, the resin will spread too quickly, causing air bubbles to be mixed in, and the spread resin will spread to the outer edge of the board. This is because not only do they protrude from the inner edge of the substrate and cause dust to form, but the generated dust also adheres to the substrate surface and reduces the reliability of the optical recording medium. . On the other hand, if the viscosity is too high, the air bubbles trapped in the resin will become difficult to move, making it difficult to remove the air bubbles, and sufficient defoaming may not be possible.

Methods for heating such a curable resin include heating from the back side of the stub bar using a heating means such as a heater, or using a coating nozzle as a coating means used when laminating the resin on the stan bar. For example, heating may be performed by disposing a heating means such as a heater in the area. However, heating at too high a temperature may cause deterioration of the resin.
If the heating temperature is too low, defoaming may be difficult, so heating is preferably carried out at a temperature of approximately 60°C or higher and 100°C or lower. Furthermore, when heating the resin on the stand bar, it is possible to heat the resin except for the portions corresponding to the outer and inner edges of the substrate to be placed on the resin, as shown in FIG. 2, which will be described later. , is preferable from the viewpoint of preventing the resin from sticking out.

As the substrate placed on the resin, it is possible to use various materials such as glass as well as plastics such as the aforementioned polycarbonate resin, acrylic resin, and epoxy resin.

[Examples] In order to explain the present invention more specifically, Examples of the present invention are shown below. - Example First, a disc-shaped stub bar 2 as illustrated in FIG. 2, which was engraved with unevenness corresponding to the shape of the guide groove, was made into a quasi-ff, 'r.

This stanbar 2 has a hardening resin 1 laminated thereon.
The stand bar 2 is placed on a carrier 3 on which a heater 5 for heating is fixed, and a substrate (not shown) is placed at the center of the stand bar 2.
A central shaft 4 is provided for alignment with the main body.

Next, - place the ultraviolet curable resin 1 (
After applying 1.1 g of product name: MRA-5000 (manufactured by Mitsubishi Rayon Co., Ltd.) in a donut shape for 15 minutes,
When the resin 1 was heated at 70° C. for 1 minute, air bubbles in the resin were removed. The viscosity of this resin when heated is 10
IQOcps was at 0°C.

After the above heating was completed, a glass substrate with a diameter of 200 mm, an inner diameter of 35 mm, and a thickness of 1.1 [0111] was placed on the resin, and then ultraviolet rays were irradiated to harden the resin.
The substrate on which the resin had been cured and integrated was released from the mold to obtain a substrate for an optical recording medium having guide grooves made of a curable resin.

The substrate for optical recording media obtained in this way does not contain any air bubbles, has no resin extrusion that can cause the formation of flakes, and has extremely high reliability with no defects in the guide grooves caused by air bubbles. It was something.

[Effects of the Invention] As explained above, the method of the present invention makes it possible to easily and easily remove air bubbles mixed into the curable resin, and eliminates guide groove defects caused by air bubbles. It is now possible to provide a highly reliable substrate for optical recording media.

[Brief explanation of the drawing]

FIG. 1 is a schematic sectional view illustrating an example of the defoaming process of air bubbles in a curable resin in the method of the present invention, and FIG. 2 is a schematic diagram of an example of a stand bar suitable for embodying the method of the present invention. FIG.

Claims (2)

[Claims] (1) After laminating a curable resin on a mold having unevenness corresponding to the shape of the guide groove, a substrate is placed on the resin, and then the resin is cured to form a guide groove made of the curable resin. A method for manufacturing a substrate for an optical recording medium, which comprises: heating and degassing the curable resin before placing the substrate on the curable resin. A method of manufacturing a substrate for an optical recording medium. (2) The curable resin has a viscosity of 150 at 100°C.
cps or less, and the heating temperature during heating of the curable resin is about 60° C. or more, the method for manufacturing a substrate for an optical recording medium according to claim 1.