JPH0952264A - Manufacture of board for optical disk medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To regulate the speed of supplying the air and opening a mold at the time of releasing a board after injection molding to reduce the double transfer of a pin of the cause of the error of an optical disk in the case of manufacturing a board for an optical disk medium. SOLUTION: The method for manufacturing a board for an optical disk medium comprises the steps of injecting melted synthetic resin in the cavity of a mold having a stationary mold, a movable side mold and a stamper provided between the stationary mold and the movable mold to mold the resin board, opening the mold and removing the board. The air is supplied between the mold and the board opposed to the mold having the stamper 4 to 2 seconds before the mold is opened, the air is supplied between the stamper and the mold 0.5 to 1 second after it, and the mold is opened at the speed of 3 to 20mm/ sec (V1 ) at the moving distance of the mold of 0 to 0.1mm and 5 to 30mm/sec (V2 ; V2 V1 ) at the moving distance of 0.1 to 1mm.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a manufacturing method for molding a thin disk-shaped plastic disk substrate used in a recording medium capable of optically writing and erasing information by injection molding.

[0002]

2. Description of the Related Art An optical disk medium using a substrate is portable and is expected to develop in the future as a high density recording medium. As a material for the substrate, plastic is advantageous in terms of cost, and there are polycarbonate (PC), polymethylmethacrylate (PMMA), and the like, and PC is mainly used because of its optical characteristics and water absorption. As a manufacturing method, injection molding is used among various moldings from the viewpoint of mass productivity. On the optical disk, fine guide grooves and pits transferred from the stamper are engraved on the surface of the substrate, and a recording film and a protective film are formed on the surface. Materials for the recording film include magneto-optical recording type such as TbFeCo and phase change recording type such as GeTeSb.

[0003]

Although a guide groove and pits are transferred to the surface of a substrate molded by injection molding, pit misalignment and double transfer of pits may occur depending on conditions during molding and substrate removal. It is often seen to do. When these occur, there is a problem that it causes an ID error in the pit portion and a data burst error in the groove portion. An object of the present invention is to establish a manufacturing method for injection-molding a substrate for an optical disc medium, which is free from these pit shifts and double transfer.

[0004]

Means for Solving the Problems The inventors of the present invention have conducted extensive studies to establish a substrate manufacturing technique for an optical disc using a synthetic resin as a substrate without pit shift or double transfer. It was found that the occurrence of the transfer was caused by the timing of releasing the substrate from the mold and the speed of opening the mold. That is, when the resin is injected into the mold and the substrate is molded, the substrate is in close contact with the mold, and it is difficult to take out the substrate when the mold is opened as it is. Therefore, before the mold is opened, air is usually supplied between the mold and the molded substrate to separate the mold from the substrate. At that time, if the timing of supplying air is bad, fluttering will occur on the substrate, and if the mold opening speed is not appropriate, fluttering will occur similarly, and it is speculated that pit displacement and double transfer will occur, As a result of examining the above-mentioned various conditions, pit shift and double transfer can be significantly reduced, and the present invention has been achieved. The gist of the present invention is as follows.

That is, molten synthetic resin is injected into a cavity of a molding die including a fixed-side die, a movable-side die and a stamper provided between them to form a resin substrate and open the die. In the method of manufacturing a substrate for an optical disk medium for taking out the substrate, air is supplied between the mold and the substrate facing the mold equipped with the stamper from 4 seconds to 2 seconds before opening the mold, and 0.5 seconds from this. After 1 second, air is supplied between the stamper and the substrate, and the moving distance of the mold is from 0 mm to 0.
For optical disk media characterized by opening the mold at a speed of 3 to 20 mm / sec (v ₁ ) up to 1 mm and 5 to 30 mm / sec (v ₂ : where v ₂ ≧ v ₁ ) from 0.1 mm to 1 mm The gist of the invention is a substrate manufacturing method. Hereinafter, the present invention will be described in more detail.

FIG. 1 is a schematic sectional view showing a molding apparatus for an optical disk substrate used in the present invention, and FIG. 2 is a schematic sectional view in the vicinity of the substrate after molding the substrate in the apparatus of FIG. 1 and before opening a mold. It is a figure. The molten resin passes from the injection mechanism 1 through the flow path 4 and is filled in the cavity 5 and molded to form the substrate 8. At this time, guide grooves and pits formed on the surface of the stamper 6 are transferred and formed on the surface of the substrate 8. An outer peripheral ring 7 is provided to define the cavity 5. After that, the movable mold 3 is opened, and the molded substrate 8 is taken out. When taken out, the substrate 8 is in close contact with the molds 2 and 3, and it is necessary to supply air between both molds and the substrate in advance to separate the substrates from each other. That is, before the mold is opened, air is supplied between the fixed side mold 2 and the substrate 8, that is, from the arrow (1) to release the substrate 8 from the fixed side mold 2, and then the stamper 6 and the substrate 8 are separated. Air is supplied in the interval, that is, from the arrow (2) to release the substrate 8 from the movable mold 3, the movable mold is opened, and the substrate is taken out.

Therefore, in the present invention, the timing (A) for supplying air between the fixed side mold 2 and the substrate 8 is 4 to 2 seconds before the mold is opened, and between the stamper 6 and the substrate. The timing (B) for supplying air is 0.5 to 1 second after (A), and the speed for opening the mold is 3 to 20 mm / sec (v _{1 for} the moving distance of the movable mold 3 from 0 mm to 0.1 mm). ), 0.1m
from m to 1mm 5~30mm / s (v _2: where v ₂ ≧
v ₁ ) and take out the substrate. Under the above conditions, the substrate can be taken out from the mold without causing the substrate to flutter.

According to the present invention, in manufacturing a substrate for an optical disc medium, the substrate is taken out by adjusting the air blow and the opening speed of the mold at the time of releasing the substrate after injection molding.
As a result, the substrate can be taken out from the mold without causing the substrate to flutter, and pit shift and double transfer can be reduced.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be specifically described below with reference to Examples and Comparative Examples, but the present invention is not limited thereto. Example 1 A polycarbonate having an average molecular weight of about 15,000 (trade name: AD-9000TG, manufactured by Teijin Chemicals Ltd.) was molded into a disk shape having a diameter of 86 mm and a thickness of 1.2 mm by using an injection molding machine. Set the stamper on the movable side mold, mold clamping force 30ton, mold temperature 1
The temperature was 20 ° C., the cylinder temperature was 340 ° C., the injection filling was 0.3 seconds, and the injection was followed by cooling in the mold for 10 seconds. Open the mold after molding 3
From the second before, air was supplied at a rate of 3 liters / minute between the fixed side mold and the molded disk substrate. Further, 2 liters / minute of air was supplied between the disk substrate and the stamper 2 seconds before opening the mold. The mold was opened at a moving distance of 5 mm / sec from 0 mm to 0.1 mm, 10 mm / sec from 0.1 mm to 1 mm, and then at 140 mm / sec, and the substrate was taken out.

A microscope and a tunnel microscope (STM KURASURF-10 manufactured by STM Kurashiki Spinning Co., Ltd.)
As a result of observation in 1), no pit displacement or double transfer was observed in the pre-pit portion such as the ID portion. A magneto-optical recording type magnetic material was formed on these substrates by a sputtering method, and an ID error and a burst error were measured by an optical disk drive. As shown in Table 1, when 25 disks were measured, the average number of errors was 23, and no burst error in the data part was observed.

[0011]

[Table 1]

Comparative Example 1 For comparison, air is supplied between the fixed side mold and the disk substrate from 3 seconds before the mold is opened, and between the stamper and the disk substrate at the same time when the mold is opened. And moving distance 0 mm
Except for opening the mold from 1 to 1 mm at a speed of 30 mm / sec,
It carried out on the same conditions as Example 1. The results are also shown in Table 1.

Comparative Example 2 For comparison, air is supplied between the fixed side mold and the disk substrate from 3 seconds before the mold is opened, and between the stamper and the disk substrate at the same time when the mold is opened. The conditions were the same as in Example 1 except for the above. The results are also shown in Table 1.

COMPARATIVE EXAMPLE 3 For comparison, an example was applied except that air was supplied from 3 seconds before opening the mold to between the fixed mold and the disk substrate and between the stamper and the disk substrate. It carried out on the same conditions as 1. The results are also shown in Table 1.

Comparative Example 4 For comparison, the same conditions as in Example 1 were used except that the mold was opened at a moving distance of 0 mm to 1 mm at a speed of 30 mm / sec. The results are also shown in Table 1.

As shown in Table 1, in the comparative example, double transfer was observed on the inner peripheral portion or the outer peripheral portion of the molded substrate. Further, when a recording film was attached and an error was measured, a burst due to this double transfer was observed. An error has occurred.

[0017]

As described above, according to the present invention, the double transfer at the time of releasing the substrate after the injection molding of the substrate for the optical disc medium is remarkably reduced, so that the error of the optical disc is significantly reduced. You can

[Brief description of drawings]

FIG. 1 is a schematic sectional view of an injection molding apparatus used in an example of the present invention.

2 is a schematic cross-sectional view of the vicinity of the substrate after the substrate is molded and before the mold is opened in the apparatus of FIG.

[Explanation of symbols]

 1 Injection Mechanism 2 Fixed Side Mold 3 Movable Side Mold 4 Flow Path 5 Cavity 6 Stamper 7 Outer Ring 8 Substrate (1), (2) Release Air

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Makoto Saito 2-13-1 Isobe, Gunma Prefecture, Annaka City, Shin-Etsu Kagaku Kogyo Co., Ltd., Institute for Precision Materials (72) Inventor, Toshimi Kobayashi Annaka City, Gunma Prefecture 2-13-1 Isobe Shin-Etsu Chemical Co., Ltd. Precision Materials Research Laboratory

Claims (1)

[Claims] 1. A molten synthetic resin is injected into a cavity of a molding die including a fixed-side die, a movable-side die, and a stamper provided therebetween to form a resin substrate, and the die is opened. In the method of manufacturing a substrate for an optical disk medium for taking out the substrate, air is supplied between the mold and the substrate facing the mold equipped with the stamper from 4 seconds to 2 seconds before opening the mold, and 0.5 seconds from this. Air is supplied between the stamper and the substrate after 1 second, and the moving distance of the mold is from 0 mm to 0.1 mm.
3 to 20 mm / sec (v ₁ ), 0.1 mm to 1 mm 5 to
A method for manufacturing a substrate for an optical disk medium, which comprises opening the mold at a speed of 30 mm / sec (v ₂ : where v ₂ ≧ v ₁ ).