JPH11339330A - Molding apparatus for substrate for information recording disk and molding method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a molding apparatus capable of suppressing the generation of projections on a surface by providing an outer peripheral member which is a component member of a mold for forming a substrate molding part and forms the outer peripheral edge of a substrate for an information recording disk with a gas leading-out path communicating with the outside from the molding part and connecting a gas suction means to the gas leading-out path. SOLUTION: The outer peripheral member 14 on a movable side is provided with the gas leading-out path 20 which leads the gas of the resin generated in a cavity to the outside. The gas leading-out path 20 is connected to a suction device 26, such as, for example, a vacuum pump, constituting the gas suction means via a pipeline 25 constituting the gas suction means. The gas leading-out path 20 is disposed on the surface of the outer peripheral member 14 on the movable side facing a stationary mold (outer opposite surface) and a surface facing one end face of a molding core 13 on the movable side (inner opposite surface). An annular projecting part is formed on the inner peripheral side of the outer opposite surface of the outer peripheral member 14 on the movable side and the spacing formed by bringing the outer opposite surface of the outer peripheral member 14 on the movable side and the one end face of the stationary mold into tight contact with each other is constituted as the gas leading-out path 20.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a molding apparatus and a molding method for molding an information recording disk substrate of an information recording disk for recording and reproducing information.

[0002]

2. Description of the Related Art Conventionally, for a magnetic disk for recording and reproducing information by a magnetic recording method, a magnetic disk substrate made of metal such as aluminum or glass is used, but these are generally expensive. In recent years, magnetic disk substrates made of inexpensive and lightweight resin have been developed because of their weight and weight. Since such a resin-made magnetic disk substrate can be mass-produced in a short time by injection molding, the price of the magnetic disk itself using this resin-made magnetic disk substrate can be reduced.

When a magnetic disk substrate is injection molded, it is necessary to attach a stamper prepared in advance to a molding die of an injection molding machine. This stamper is made of nickel plating having a thickness of 1 mm or less from the viewpoint of productivity. A process for forming such a stamper will be described with reference to FIG. First, the surface of a disk-shaped glass master 40 is polished (FIG. 3A), and a resist 41 is applied to the surface by spin coating or the like (FIG. 3B). Since the surface of the glass master 40 is mirror-finished, the surface of the applied resist 41 also has a mirror surface reflecting the surface properties of the glass master 40.

Next, a predetermined fine pattern is formed on the surface of the resist 41 by an etching method or the like. Then, the surface of the resist 41 is plated with Ni (nickel). As a result, Ni is deposited on the surface of the resist 41 to form the original shape of the stamper composed of the plating layer 42 (FIG. 3C). Finally, the plating layer 42 is peeled off from the resist 41 to form a stamper 43 (FIG. 3D). And this stamper 4
3 is mounted on the movable and fixed surfaces of a molding die 44 of an injection molding machine to injection-mold a magnetic disk substrate (FIG. 4E).

[0005]

When the magnetic disk substrate is taken out of the injection molding machine after the injection molding by the injection molding machine described above, the magnetic disk substrate is taken out of the stamper 43 mounted on the molding die 44. It needs to be released.
However, if the material of the stamper 43 and the filler of the resin are insufficiently selected, the mold release becomes non-uniform, and so-called ghost pits or pit shifts occur in the fine pattern formed on the magnetic disk substrate. There was a case.

When a magnetic disk using such a magnetic disk substrate is used, the projection causes a fine spacing variation between the magnetic head and the surface of the magnetic disk, and causes a variation in the amplitude of the reproduced signal. cause. Then, the amplitude fluctuation of the reproduction signal increases the fluctuation of the recording signal,
There was a problem that resulted in a reading error. Also,
There is also a possibility that the magnetic head or the head slider may be damaged by contacting the projection.

On the other hand, in order to avoid the problem of mold release from the stamper 43, there is an injection molding method in which a fine pattern is directly formed on the molding die 44 to eliminate the need for the stamper 43. When the gas of the molding resin is unevenly released from the divided surface, when the magnetic disk substrate is released from the molding die 44, a part of the fine pattern formed on the magnetic disk substrate may be projected. Eventually, the same phenomenon as when the stamper 43 is used occurs.

The present invention has been made in view of the above circumstances, and has as its object to provide an apparatus and a method for forming a substrate for an information recording disk, which can suppress the occurrence of surface protrusions.

[0009]

According to the present invention, there is provided, according to the present invention, a mold for forming a molded portion for an information recording disk substrate, and a molding for molding the information recording disk substrate in the molded portion. In the apparatus, a gas lead-out path communicating from the molding portion to the outside is provided on an outer peripheral member for forming an outer peripheral edge of the information recording disk substrate, which is a component of the mold, and a gas suction path is provided in the gas lead-out path. This is achieved by connecting means. Further, according to the present invention, the object is to form a molded portion for an information recording disk substrate, fill a molded material in the molded portion, and emit gas generated from the filled molding material from the molded portion to the outside. It is attained by suctioning and exhausting and molding the information recording disk substrate.

According to the above configuration, the outer peripheral member is configured so that the clearance between the outer peripheral member and the component of the mold in contact with the outer peripheral member is wider than in the related art, and the gas generated from the molding material is forcibly sucked. Since the gas is exhausted to the outside, the gas flow becomes uniform, and even when molding without using a stamper, when the information recording disk substrate is released from the mold after molding, it is formed on the information recording disk substrate. It can be suppressed that a part of the fine pattern is projected.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings. The embodiment described below is a preferred specific example of the present invention, and thus various technically preferable limitations are added. However, the scope of the present invention particularly limits the present invention in the following description. It is not limited to these forms unless otherwise stated.

FIG. 1 is a sectional side view showing a main part of an embodiment of an information recording disk substrate molding apparatus according to the present invention. The molding apparatus 10 is an injection molding machine, and is an apparatus for molding a magnetic disk substrate that is an information recording disk substrate. In the molding apparatus 10, a stationary molding core 11 constituting a stationary mold 10A is attached to a stationary portion of an injection molding machine via an outer peripheral member 12, and a movable molding core 13 constituting a movable mold 10B. Is attached to the movable part of the injection molding machine via the outer peripheral member 14.

The fixed-side molding core 11, the movable-side molding core 13, and the movable-side outer peripheral member 14 form a cavity that is a molding portion for a magnetic disk substrate filled with a resin as a molding material. You. That is, the fixed-side molding core 11 and the movable-side molding core 13 are molds for molding the front and back surfaces of the magnetic disk substrate. It is a mold to be molded.

A gate block 16 is provided which penetrates from the other end surface of the fixed molding core 11 to the center of the cavity and has a gate 15 for guiding resin into the cavity. A cutter 17 penetrating from the other end surface of the movable-side molding core 13 to the center of the cavity and cutting a portion serving as a center hole of the magnetic disk substrate, and a core 18 for extruding the portion are provided.

As a characteristic part, the movable outer peripheral member 14 is provided with a gas lead-out passage 20 for leading the resin gas generated in the cavity to the outside. The gas lead-out path 20 is connected to a gas suction device 26 such as a vacuum pump that constitutes the gas suction means via a pipe 25 that constitutes the gas suction means. As shown in the enlarged sectional side view of FIG. 2, the gas outlet path 20 has a surface (hereinafter, referred to as an outer facing surface) of the movable outer peripheral member 14 facing the fixed mold 10A and a movable molding core 13. (Hereinafter referred to as the inner facing surface)
It is provided in.

That is, a height a (for example, 0.005 mm to 0.0
40 mm) and a ring-shaped convex portion 14a having a width c (for example, 0.1 mm to 1 mm) is formed. When the outer facing surface of the movable outer peripheral member 14 and one end surface of the fixed mold 10A are in close contact with each other. The gap formed is configured as the gas outlet path 20. Furthermore, the height b (for example, 0.005 mm to 0.04 mm) is also provided on the inner peripheral side of the inner facing surface of the movable outer peripheral member 14.
0 mm) and a ring-shaped convex portion 14b having a width d (for example, 0.1 mm to 1 mm), and the inner facing surface of the movable side outer peripheral member 14 and one end surface of the movable side forming core 13 are in close contact with each other. The gap formed at this time is also configured as the gas outlet path 20. Although the tops of the ring-shaped convex portions 14a and 14b are formed in flat portions having the widths c and d, the same effect can be obtained by forming them in an edge shape where the widths c and d are 0. .

FIG. 3 is an enlarged sectional side view showing a second example of the gas outlet path provided on the movable outer peripheral member.
The gas outlet path 21 is provided on a surface (hereinafter, referred to as an inner peripheral side facing surface) facing the outer peripheral surface of the outer peripheral member 24 on the movable side and a lateral peripheral surface of the molding core 13 on the movable side. That is, a ring-shaped convex portion 24a having a height a (for example, 0.005 mm to 0.040 mm) and a width c (for example, 0.1 mm to 1 mm) is formed on the outer peripheral surface of the movable outer peripheral member 24 on the inner peripheral side.
Is formed, and a gap formed when the outer facing surface of the movable-side outer peripheral member 24 and one end surface of the fixed mold 10 </ b> A are in close contact with each other is configured as the gas outlet path 21.

Further, the inner peripheral surface of the movable outer peripheral member 24 has a height b (for example, 0.005 mm to
0.040 mm), width d (for example, 0.1 mm to 1 mm)
Of the outer peripheral member 24 on the movable side and the molding core 13 on the movable side.
The gap formed when the side peripheral surface is in close contact is configured as the gas outlet path 21. In addition, the ring-shaped convex portions 24a, 2
The top of 4b is formed as a flat portion having widths c and d,
The same effect can be obtained even if the width c and d are formed in an edge shape with 0.

FIG. 4 is an enlarged sectional side view showing a third example of the gas outlet path provided on the outer peripheral member on the movable side.
The gas outlet path 22 is provided on the outer facing surface and the inner facing surface of the outer peripheral member 14 on the movable side. That is, a ring-shaped recessed portion 14c which is concentric with the inner periphery and has a semicircular cross section (for example, a radius of 0.1 mm to 1 mm) is formed on the outer facing surface of the outer peripheral member 14 on the movable side. A gap formed when the outer facing surface of the outer peripheral member 14 on the side and the one end surface of the fixed mold 10 </ b> A come into close contact with each other is configured as a gas outlet path 22.

Further, a ring-shaped concave portion 14d concentric with the inner periphery and having a semicircular cross section is formed on the inner facing surface of the outer peripheral member 14 on the movable side. A gap formed when the inner facing surface and one end surface of the movable-side molding core 13 are in close contact with each other is configured as a gas outlet passage 22. The same effect can be obtained not only in a semicircular shape but also in a polygonal shape such as a triangle or a rectangle for the cross section of the ring-shaped concave portions 14c and 14d. Further, if a plurality of ring-shaped concave portions 14c and 14d are formed concentrically, the exhaust efficiency can be further improved.

FIGS. 5A and 5B are an enlarged plan view and an enlarged cross-sectional side view showing a fourth example of the gas outlet passage provided in the movable outer peripheral member. This gas outlet 23 is
It is provided on the outer facing surface and the inner facing surface of the outer peripheral member 14 on the movable side. That is, the height a (for example, 0.005 mm to 0.
040 mm) and a ring-shaped convex portion 14e having a width c (for example, 0.1 mm to 1 mm), and a substantially fan-shaped planar shape over the entire outer periphery of the ring-shaped convex portion 14e, and a cross-sectional shape thereof. A substantially triangular concave portion 14g is radially formed, and a gap formed when the outer facing surface of the movable outer peripheral member 14 and one end surface of the fixed mold 10A are in close contact with each other is configured as a gas outlet passage 23. Is done.

Further, a height b (for example, 0.005 mm to 0.1 mm) is also provided on the inner peripheral side of the inner facing surface of the movable outer peripheral member 14.
040 mm) and a ring-shaped convex portion 14f having a width d (for example, 0.1 mm to 1 mm), and the planar shape is substantially fan-shaped over the entire outer periphery of the ring-shaped convex portion 14f, and the cross-sectional shape is A substantially triangular concave portion 14h is formed radially, and a gap formed when the inside facing surface of the movable outer peripheral member 14 and one end surface of the movable molding core 13 are in close contact with each other. 23.

An operation example of such a configuration will be described with reference to FIGS. First, the movable mold 10B is moved to close the cavity (FIG. 6). Then, the molten resin is filled into the cavity via the gate 15, and the gas suction device 26 is operated at the same time. Here, as a resin material of the magnetic disk substrate, for example, PC (Poly Carb) used for CD (Compact Disk) is used.
onate), APO sometimes used for optical discs
(Amorphous Poly Olefin) resin, PMMA (Poly Polyolefin) used for video discs
Methyl Meta Acrylate) is used.

At this time, the gas generated from the molten resin is:
By the suction force of the gas suction device 26, the gas outlet path 20, that is, between the outer facing surface of the movable outer member 14 and one end surface of the fixed mold 10 </ b> A, and the outer peripheral member 14 of the movable It is guided to the outer peripheral portion of the outer peripheral member 14 on the movable side through the space between the inner facing surface and one end surface of the molding core 13 on the movable side, and finally exhausted to the outside through the conduit 25 (FIG. 7). ). Since the series of gas flows spread concentrically and uniformly, it is possible to eliminate protrusions of the fine pattern of the magnetic disk substrate that have occurred at places where the gas flows are not uniform.

Next, the cutter 17 is projected into the cavity to cut the inner diameter of the molten resin (FIG. 8). Then, the resin is cooled and solidified, the cutter 17 is returned into the movable mold 10B, and the core 18 is projected into the cavity. The movable mold 10B is moved to open the cavity. Finally, the magnetic disk substrate 30 and the sprue (part of the inner diameter of the resin cut by the cutter 17 and extruded by the core 18) 31 are taken out of the cavity (FIG. 9). Then, the magnetic disk substrate 30 is transported to the next step, and the sprue 3
1 is discarded.

In the above-described embodiment, a magnetic disk on which a fine pattern is formed, that is, a so-called pre-emboss type magnetic disk has been described as an example. However, an information recording disk on which a fine pattern is formed is not particularly limited. However, the present invention can be applied to, for example, an optical disk and a magneto-optical disk.

[0027]

As described above, according to the present invention, it is possible to obtain a thin disk in which the occurrence of projections on the surface is suppressed.

[Brief description of the drawings]

FIG. 1 is a sectional side view showing a main part of an embodiment of an information recording disk substrate molding apparatus according to the present invention.

FIG. 2 is an enlarged sectional side view of a molding die of the molding apparatus of FIG.

FIG. 3 is a second enlarged sectional side view of a molding die of the molding apparatus in FIG. 1;

FIG. 4 is a third enlarged sectional side view of a molding die of the molding apparatus of FIG. 1;

FIG. 5 is a fourth enlarged sectional side view of a molding die of the molding apparatus of FIG. 1;

FIG. 6 is a first sectional side view showing an operation example when performing injection molding using the molding apparatus of FIG. 1;

FIG. 7 is a second sectional side view showing an operation example when performing injection molding using the molding apparatus of FIG. 1;

FIG. 8 is a third sectional side view showing an operation example when performing injection molding using the molding apparatus of FIG. 1;

FIG. 9 is a fourth sectional side view showing an operation example when performing injection molding using the molding apparatus of FIG. 1;

FIG. 10 is a diagram showing an example of a conventional method for manufacturing a stamper for an information recording disk substrate.

[Explanation of symbols]

10 molding apparatus, 10A fixed die, 10B
..Movable molds, 11: molding cores on the fixed side, 12
..Outer peripheral member on fixed side, 13: molding core on movable side, 14: outer peripheral member on movable side, 20, 21, 22,
23 ... gas outlet path, 25 ... pipe line, 26 ... gas suction device

Claims (3)

[Claims] 1. A molding apparatus having a mold for forming a molded portion for an information recording disk substrate, wherein the molding device molds the information recording disk substrate in the molded portion. An outer peripheral member for forming an outer peripheral edge of the recording disk substrate, a gas lead-out path communicating from the molding portion to the outside, and a gas suction means connected to the gas lead-out path; Molding equipment. 2. The apparatus for forming a substrate for an information recording disk according to claim 1, wherein the gas outlet path is provided over the entire circumference of the outer peripheral member. Forming a molding portion for an information recording disk substrate, filling the molding portion with a molding material, sucking and discharging gas generated from the filled molding material to the outside from the molding portion; A method for forming an information recording disk substrate, comprising forming a disk substrate.