JPH05109125A - Production of optical disk and material thereof - Google Patents

Abstract

PURPOSE:To eliminate double transfer at the time of disk molding of low-density pits. CONSTITUTION:The disk of the low-density pits which is smaller in the area of grooves, etc., than the area over the entire part of the optical disk for information is produced. An additive contg. a component to increase the surface tension of the master disk is added at <=0.01wt.% to the molding material to increase an anchor effect at the time of peeling the disk after transferring the pits, etc., from the master disk at the time of molding.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing an optical disk having a relatively small area density of pits to be transferred and its material.

[0002]

2. Description of the Related Art Optical discs can be recorded / reproduced only once such as a read-only type such as a CD or LD, a CD-R, a write-once type disc for information, a so-called write-once type, a repetitive recording / reproducing type such as a phase change disc. The write-once type and the write-once type are widely used in recent years for storing information such as computer files because of their large storage capacity.

As a tracking system for these optical disks, a continuous servo system and a sample servo system are known. The continuous servo system has been developed in the past, but the sample servo system has recently been put into practical use because of its good tracking stability.

In this sample servo system, the servo area and the data area are completely separated. However, especially in the write-once type and the write type, since the user records the data after the disk is manufactured, only the pits in the servo area are manufactured at the time of manufacturing the disk. It does not exist, and the number of pits to be transferred is extremely small as compared with the read-only type CDs and LDs that have been practically used so far.

This disk is manufactured by filling a mold of a predetermined shape with a molding material (here, a plastic resin) by an injection molding method. FIG. 1 is a diagram schematically showing a cross section of an injection molding die used for the injection molding. Reference numerals 1 and 2 denote molds, 3 denotes a master (stamper), 4 denotes mold cavities, and 5 denotes sprues formed in the introduction portion of the molding material. Usually, this injection molding is carried out by injection-filling a molding material (resin) that has been melted by heating into a mold cavity 4 that has been closed in advance, and then solidifying or curing it to mold it. When the molded product is taken out of the mold, a mold release agent is used to facilitate the mold release operation between the mold and the molded product.

Stamper 3 arranged in molding dies 1 and 2
The pits are transferred to the molding material (plastic resin) as the base material, and the transferred molded product is separated from the mold and taken out as the disk substrate. At this time, the plastic resin shrinks rapidly when it solidifies by cooling. .. At this time, in the case of a CD having a large pit density and a disc having a large pit density such as a read-only type having a data portion among the microminiature information discs (PO), the pits act as a stopper (anchor effect), and the formed plastic The substrate is fixed to the stamper if it is not peeled off by the releasing operation even if the mold is opened.

However, since this release agent also has the property of increasing the surface tension of the stamper 3, when the molded disk substrate is peeled from the mold, the anchor effect is reduced, so that high density is achieved. It is convenient in the case of pits, but in the case of low density pits, the pits do not work as anchors, and since the plastic substrate begins to shrink upon cooling when the mold is opened, it has already been molded by the convex pits of the stamper 3. A so-called double transfer state occurs in which the pit is destroyed and a tail is drawn from the inner peripheral portion to the outer peripheral portion, and an abnormality occurs in the tracking signal generated from the pit, and the tracking does not operate normally.

Further, as the number of moldings is increased, the release agent is gradually accumulated on the surface of the stamper 3, further increasing the double transfer. In order to solve this problem, in Japanese Patent Laid-Open No. 63-21137, grooves and pits are provided on a plurality of tracks inside and outside the track area having a sample mark, thereby increasing the anchor effect. The technology is disclosed.

Further, in Japanese Patent Application No. 3-122285, an intermittent groove (groove) is provided inside and outside of a track area having a sample mark, and mirror parts are arranged in proximity to the track area and synchronized with the sample mark. To 0.2
A technique for increasing the anchor effect by providing a width of 5 mm to 0.75 mm is disclosed.

[0010]

However, the above method cannot completely prevent the shrinkage of the plastic resin only by the continuous groove or the like which can be arranged only in an area other than the necessary area. That is, although a great effect is exerted in the outer peripheral portion in the immediate vicinity of the continuous groove arranged in the vicinity of the region having the sample mark, the formability of the pit located in the inner periphery of the outermost peripheral portion by about 0.5 mm is improved. The effect is poor, and as a result, a good tracking signal cannot be obtained.

An object of the present invention is to solve such a problem, and to provide a method of manufacturing an optical disk and a material for the same, which can eliminate a double transfer at the time of molding a disk of low density pits and obtain a good tracking signal. To do.

[0012]

In order to solve the above-mentioned problems, the optical disk manufacturing method according to claim 1 of the present invention is such that when a disc is peeled after transferring pits or the like from the master during molding, the master is used as a molding material. An additive containing a component for increasing the surface tension is added in an amount of 0.01% by weight or less.

In order to solve the above-mentioned problems, a second aspect of the present invention is provided.
In the optical disc manufacturing method according to the first aspect, when the pits and the like are transferred from the master during molding and the disc is peeled off, 0.01% by weight or less of a release agent containing a component that increases the surface tension of the master is added to the molding material. .. As the molding material, it is preferable to use a polycarbonate resin or an acrylic resin that satisfies various conditions.

[0014]

According to the optical disc manufacturing method of the present invention,
The anchor effect is enhanced by reducing or eliminating the content of the additive or the release agent containing the component for increasing the surface tension of the master for peeling the stamper and the resin.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A method of manufacturing an optical disk according to the present invention and its material will be described below. As a molding material for an injection-molded optical disc, it is optically transparent, does not disturb the deflection characteristics, has a small water absorption rate, can sufficiently protect the recording layer, has good flatness, has a small change in shape over time, and is inexpensive. A polycarbonate resin or an acrylic resin is used as a material satisfying the condition that the surface is not easily scratched. Acrylic resin has a high water absorption rate (1% or more), and polycarbonate resin has a large birefringence and has a problem in optical characteristics. However, polycarbonate resin has practically no problem due to a significant improvement in the injection molding process. Due to the improvement, this polycarbonate resin is often used as a molding material. Among them, the information disk is a polymerization inhibitor that protects the recording layer (thin film) formed after molding from deterioration in comparison with the material (CD grade) manufactured for general CD from the viewpoint of data storability, Use materials with the least amount of unreacted monomers and other additives.

Although there is a problem in terms of reliability, it is also possible to use a polyolefin-based substrate having a birefringence and a small water absorption rate of one digit or more as compared with a polycarbonate resin.

By the way, in order to improve productivity by facilitating the separation of the disk molded in the mold cavity 4 from the stamper 3 and the molds 1 and 2, these materials are separated from fatty acid ester, stearic acid monoglyceride and the like. A mold agent is added. That is, conventionally, the mold release agent is attached to the molds 1 and 2 or the stamper 3 to increase the surface tension of the molds 1 and 2 or the stamper 3 to prevent the resin from adhering to the molds 1 and 2 or the stamper 3 to facilitate the peeling. ing.

However, as described above, since the release agent increases the surface tension of the stamper 3, when the molded disk substrate is peeled from the mold, the anchor effect is reduced, which is so-called two. A double transfer state is generated.

Therefore, in molding a low density pit disk, a releasing agent is not particularly required for peeling the stamper 3 and the resin. Therefore, when the pit or the like is transferred from the stamper when the pit or the like is peeled off, the disk is peeled off. The molding material contains 0.01% by weight or less of a mold release agent necessary for peeling the solidified material such as sprue formed in the resin introduction part.

Since some additives, which are not particularly added for the purpose of releasing the mold, adhere to the stamper or the mold to have a peeling effect, in such a case, the releasing agent may not be used at all. ..

By reducing the additive in this way,
The recording layer such as a dielectric film or a metal film deposited on the surface of the disk substrate after molding does not deteriorate. Furthermore, the surface tension of the molded disk substrate decreases when the additive is reduced.

This manufacturing method and its materials are described in the above-mentioned Japanese Patent Application Laid-Open No. 63-21137 and Japanese Patent Application No. 3-12228.
When combined with No. 5, the double transfer is prevented by supporting the shift of the sample mark due to the resin material injected into the mold together with the groove area, and the effect becomes more remarkable.

[0023]

According to the optical disk manufacturing method and the material thereof according to the present invention, the following effects can be obtained. Since the content of the release agent is reduced to reduce the surface tension and increase the anchor effect, double transfer of the sample mark in the low density pits is prevented. Since the release agent and other additives are reduced, the deterioration of the recording layer (thin film) after molding is reduced. Since the surface tension can be reduced by reducing the additive, the adhesion of the recording layer (thin film) after molding can be improved. As a result of the above effects, the weather resistance can be improved.

[Brief description of drawings]

FIG. 1 Schematic diagram of a mold

[Explanation of symbols]

1, 2 ... Mold, 3 ... Master (Stamper), 4 ... Mold cavity, 5 ... Sprue.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Susumu Kubo 3-12 Moriya-cho, Kanagawa-ku, Yokohama, Kanagawa Japan Victor Company of Japan, Ltd. (72) Hideo Machida 3--12 Moriya-cho, Kanagawa-ku, Yokohama Address inside Victor Company of Japan, Ltd.

Claims (3)

[Claims] 1. Recording / reproduction is possible, recording / reproduction is possible only once,
An optical disk for reproduction only or a combination of them, and by using injection molding, compression molding, or both of them, the pits, grooves, or both recorded on the master are transferred to a molding material having plasticity. In the method of manufacturing an optical disk, in which the area of the pits, grooves, etc. to be transferred is smaller than the area of the entire disk, the disk is peeled after the pits are transferred from the master during molding. At this time, 0.01% by weight or less of an additive containing a component for increasing the surface tension of the master is added to the molding material, which is a method for producing an optical disk. 2. Recording / reproduction is possible, recording / reproduction is possible only once,
An optical disk for reproduction only or a combination of them, and by using injection molding, compression molding, or both of them, the pits, grooves, or both recorded on the master are transferred to a molding material having plasticity. In the method of manufacturing an optical disk, in which the area of the pits, grooves, etc. to be transferred is smaller than the area of the entire disk, the disk is peeled after the pits are transferred from the master during molding. At this time, a release agent containing a component for increasing the surface tension of the master is added to the molding material in an amount of 0.01% by weight or less, and a method for producing an optical disk. 3. The material of the optical disk according to claim 1, wherein the molding material is a polycarbonate resin or an acrylic resin.