JP2001331983A - Molding method and molding device for optical disk - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a molding method for optical disks which can improve the quality and productivity of products by preventing the wear which occurs between a metal mold and a stamper during pouring of a resin. SOLUTION: The molding device constituted by interposing a metallic layer 3 consisting of metal having a melting point lower than the melting point of the resin 7 for molding substrates between the opposite surfaces of the metal mold 10 and the stamper 1 arranged in the prescribed position within the metal mold 10 for transferring ruggedness to the optical disk substrate is used in a molding process step for the optical disks.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disk molding method and apparatus.

[0002]

2. Description of the Related Art In a conventional optical disk molding, as shown in FIG. 3, the optical disk is placed on a lower die 102 made of SUS.
A sprue 10 is formed in a gap formed by a fixed stamper 101 made of Ni and an upper mold 110 made of SUS.
The resin poured from 6 is filled, and the irregularities engraved on the stamper 101 are transferred to the resin surface. After the irregularities engraved on the stamper 101 are transferred, the resin is cooled. After the mold opening is completed, the sprue 106 and the molded body are pushed up by the eject rod 107, and the lower mold 102
Remove the compact from After the end of the eject operation, the molded body is transferred to the outside of the molding machine. In FIG. 3, reference numeral 108 denotes a gate cut punch, and 109 denotes a cylinder.

[0003]

In the above conventional example, when the resin is injected and filled into the molds 102 and 110 from the sprue 106, the flow pressure of the resin and the heat (thermal expansion between Ni and SUS) occur. And the stamper 10).
1 and the lower mold 102 move relative to each other in a press-contact state, and a large frictional force is generated between the two. Thereby, the stamper 101
An adhesive wear phenomenon accompanied by movement of a metal component and an abrasive wear phenomenon with abrasion occur between the metal mold and the lower mold 102. Due to the adhesion and abrasion, a convex part having a height of several μm is mainly formed on the lower mold 102, and this convex part appears on the recording surface of the stamper 101, and this convex part is transferred to a molded body, resulting in a defective product. In addition, the abrasive wear mainly causes deterioration of the shape of the stamper 101 and generation of metal powder.

[0004] For the above reasons, it is necessary to replace the stamper 101 when the quality of the molded product has deteriorated beyond the allowable range. Since the replacement work must be performed frequently, productivity is reduced.

SUMMARY OF THE INVENTION In view of the above problems, the present invention prevents an abrasion phenomenon between a mold and a stamper at the time of injecting a resin, and improves the quality and productivity of a product. And a molding apparatus.

[0006]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a method for forming a mold in an optical disc, comprising: a mold and a stamper disposed at a predetermined position in the mold for transferring irregularities to an optical disc substrate; Characterized in that a molding apparatus having a metal layer made of a metal having a lower melting point than the melting point of the resin for substrate molding is interposed between the opposing surfaces.

It is preferable that the low melting point metal has a melting point of 100 ° C. or less as compared with the temperature at the time of injection of the resin for molding a substrate into a mold.
It is preferable to use any one of an alloy of i, an alloy of In, Bi, and Sn, and an alloy of Pb and Sn.

The thickness of the metal layer is preferably in the range of 30 to 150 μm.

It is preferable that the resin for molding a substrate is one of polycarbonate and acrylic.

According to the present invention, the heat of the resin during resin injection is transmitted to the metal layer via the stamper, and the metal layer changes from a solid phase to a solid-liquid phase and a liquid phase. Therefore, the relative movement between the stamper and the mold due to the flow pressure of the resin and the difference in thermal expansion is made smooth by the action of the solid-liquid phase and the liquid phase metal layer interposed between them, and the adhesion and wear phenomenon occurs. And abrasive wear phenomena can be prevented. As a result, according to the present invention, it is possible to provide an optical disk molding method and an optical disk molding apparatus capable of improving product quality and productivity.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The embodiment of the present invention shown in FIGS. 1 and 2 relates to a method and an apparatus for molding an optical disk by injection compression molding using polycarbonate as a resin for molding a substrate.

A Ni stamper 1 having an irregular surface for transferring irregularities to an optical disk substrate is fixed to the lower surface of an SUS upper mold 10 using a SUS stamper holder 5. A hollow disk-shaped metal layer 3 as shown in FIG. 2 is interposed between the upper surface of the stamper 1 and the lower surface of the upper mold 10. The metal layer 3 is made of a metal having a melting point lower than the melting point of the substrate molding resin (polycarbonate) 7, specifically, a eutectic alloy of In and Bi, and is in a solid state at normal temperature.

An optical disk is formed in the inner space of the lower SUS die 2 movably arranged, the stamper 1, and the SUS outer ring 8 arranged on the outer periphery of the upper and lower dies 10, 2. A cavity 7 is formed, and through a nozzle portion 6 formed so as to penetrate the center axis of the stamper holder 5, a resin 7 for molding a substrate in a heated and melted state is injected and filled by applying pressure. .

The upper and lower molds 10 and 2 are at 80 to 120 ° C. (for example, 100 ° C.), the molten resin temperature of the substrate molding resin (polycarbonate) 7 is 370 to 400 ° C. (for example, 380 ° C.), Each is set. Stamper 1
Has a radius of 60 mm, a thickness of 0.3 mm, a height of the uneven surface of 0.12 μm, and a pitch of 0.3 μm. Metal layer (I
eutectic alloy of n and Bi) 3 has a radius of 60 mm and a thickness of 80 μm
m, melting point about 80 ° C.

In molding an optical disk by injection compression molding, the following steps are sequentially used.

In the process of mold clamping, injection, compression, holding pressure, cooling, mold opening, and removal (injection process), the heat of the resin 7 at the time of resin injection is transmitted to the metal layer 3 via the stamper 1, and the metal layer 3 is solidified from the solid phase. The state changes to a liquid phase (or a liquid phase in some cases). Therefore, the stamper 1 due to the resin flow pressure and the difference in thermal expansion
The relative movement occurring between the upper mold 10 and the upper mold 10 is smoothly performed by the function of the solid-liquid phase metal layer 3 interposed therebetween, thereby preventing the occurrence of adhesion wear phenomenon and abrasive wear phenomenon. The pressure on the stamper 1 is evenly distributed by the cushioning action of the metal layer 3. The metal layer 3 has a thin oxide film formed on its surface, and receives heat so that the inside becomes a solid-liquid phase or a liquid phase, and becomes a state like a balloon filled with water.

In the step (compression step), the lower mold 2 rises by about 0.6 mm to compress the resin 7 in the cavity. At this time, the metal layer 3 is in a substantially liquid state. In addition, local high pressure can be prevented from acting on the stamper 1.

In the step (pressure holding step), the metal layer 3 changes from a liquid phase to a solid-liquid phase and a solid phase, and in the step (cooling step), the metal layer 3 is completely turned into a solid phase. At the same time, the resin 7
Is cooled to complete the molding of the optical disk. The step (mold opening step) and the step (ejection step) are performed by using a conventionally known method, and an optical disc as a molded product is ejected.

The thickness of the metal layer 3 is 30 to 150 μm.
, Preferably in the range of 50 to 100 μm. If it is less than 30 μm, the effect of preventing the metal layer 3 from being worn and the effect of cushioning become insufficient. On the other hand, 150 μm
Is exceeded, the oxide film formed on the surface of the metal layer 3 becomes
It is inconvenient to suffer from pressure.

The metal layer 3 may be made of an alloy of In, Bi, and Sn (in the case of a eutectic alloy,
Melting point 89.9 ° C.), In (melting point 156.4 ° C.), an alloy of Pb and Sn (melting point 183 ° C. in the case of a eutectic alloy), or the like can be used. When a metal having a melting point of 100 ° C. or less as compared to the temperature at the time of injecting the resin 7 for molding a substrate into the mold is used as the metal layer 3, the solid phase is rapidly changed from a solid phase to a solid-liquid phase and a liquid phase during the injection step. This is preferable because the state changes.

In the above embodiment, the stamper 1 is arranged at a predetermined position in the upper mold 10, but the present invention is applied to a case where the stamper is arranged at a predetermined position in the lower mold as shown in FIG. In this case, a metal layer made of a metal having a lower melting point than the resin for substrate molding may be interposed between the opposing surfaces of the lower mold and the stamper.

[0022]

According to the present invention, there is provided a method and apparatus for molding an optical disk capable of preventing a wear phenomenon occurring between a mold and a stamper at the time of injecting a resin, thereby improving product quality and productivity. Can be provided.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating an embodiment of the present invention.

FIG. 2 is a perspective view showing a metal layer.

FIG. 3 is a sectional view showing a conventional example.

[Explanation of symbols]

 Reference Signs List 1 stamper 2 lower mold 3 metal layer 7 resin for substrate molding 10 upper mold

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) B29L 17:00 B29L 17:00 (72) Inventor Shinji Sakuriku 1006 Kazuma Kazuma, Kadoma City, Osaka Matsushita Electric Industrial Co., Ltd. (72) Inventor Hiroshi Aburaya 1006 Kadoma, Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.F-term (reference)

Claims (6)

[Claims] In an optical disc molding process, a temperature lower than a melting point of a resin for molding a substrate is set between opposing surfaces of a mold and a stamper arranged at a predetermined position in the mold to transfer irregularities to an optical disc substrate. A method of molding an optical disk, characterized by using a molding device having a metal layer made of a metal having a melting point interposed. 2. The method of molding an optical disk according to claim 1, wherein the metal having a low melting point has a melting point of 100 ° C. or less as compared with a temperature at the time of injecting the resin for molding a substrate into a mold. 3. The method according to claim 1, wherein the metal having a low melting point is one of the following. In alloy of In, Bi Alloy of In, Bi, Sn Alloy of Pb, Sn 4. The method according to claim 1, wherein the thickness of the metal layer is in the range of 30 to 150 μm. 5. The method for molding an optical disk according to claim 1, wherein the resin for molding a substrate is any of the following. Polycarbonate acrylic 6. A mold, a stamper disposed at a predetermined position in the mold for transferring irregularities to the optical disk substrate, and a melting point of the resin for molding the substrate, which is disposed between the stamper and the mold. An optical disk molding device, comprising: a metal layer made of a metal having a lower melting point.