JPH05212751A - Method for molding disk substrate - Google Patents

Abstract

PURPOSE:To prevent the deformation of a stamper and improve the appearance of a disk substrate by setting the pressure A in the gas passage of a mold provided with no stamper and the pressure B in the gas passage of a movable mold provided with the stamper to A>B at the time of an entire injection process and to A<B at the time of an entire cooling process. CONSTITUTION:A disk substrate mold is constituted of a movable mold 40 provided with a stamper 30 and a fixed mold 10 provided with no stamper. The gas passage 12 of the fixed mold 10 is connected to a pressure pump 70 through a solenoid valve 50 and a pressure reducing valve 60 and also connected to a vacuum pump 80 through a solenoid valve 51. An outer peripheral gas passage and an inner peripheral gas passage 46 on a movable side are connected to the pressure pump 70 through a pressure reducing valve 61 and also connected to a vacuum pump 81 through a solenoid valve 53. At the time of an injection process wherein a molten resin 20 is injected in a resin passage 11, the pressure A in the passage 12 and the pressure B in the passages 45, 46 are set to A>B and, at the time of an entire cooling process, said pressures A, B are set to A<B. Therefore, the deformation of the stamper 30 is prevented and the surface irregularity of a disk substrate is eliminated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of molding a disk substrate.

[0002]

2. Description of the Related Art FIG. 3 shows a cross-sectional view of a main part of a conventionally used disk substrate molding die. The disk substrate molding die is composed of a movable die 40 and a fixed die 10. The molten resin 20 is poured from a resin flow path 11 provided in the fixed mold 10 into a cavity formed by the fixed mold 10 and the stamper 30 attached to the movable mold 40.

The movable mold 40 includes an outer peripheral holder 41, an inner peripheral holder 42, a punch core 43, and a punch air sleeve 4.
And 4 are provided. The stamper 30 is the outer holder 4
It is attached to the movable mold 40 by means of 1 and the inner circumference holder 42. The punch core 43 is pushed out from the movable mold 40 side to the fixed mold 10 side by a hydraulic device (not shown), so that the inner diameter of the manufactured disk substrate is punched out.

[0004]

The deformation that occurs in the stamper 30 during the injection process in which the molten resin 20 is poured into the cavity will be described with reference to FIG. When the molten resin 20 is poured into the cavity, the stamper 30 bends 31 along the flow of the molten resin 20. The flexure 31 moves from the inner peripheral side to the outer peripheral side according to the flow of the molten resin 20. When the disk substrate is repeatedly manufactured, the bending 31
Occurs repeatedly, and the stamper 30 is deformed.

Further, the state of the cooling step in which the molten resin 20 poured into the cavity is cooled will be described with reference to FIG. The center portion of the molten resin 20 filled in the cavity is cooled after the punch core 43 is moved to the fixed mold 10 side and punched out, thereby forming a disk substrate.

The molten resin 20 shrinks as it is cooled, and may be separated from the stamper 30. There is a difference in cooling rate between the peeled portion and the other non-peeled portion. Therefore, the peeled portion produces a pattern different from that of the non-peeled portion, and so-called defective appearance occurs.
The deformation of the stamper 30 prevents accurate information from being transmitted to the manufactured disc substrate, and the appearance defect reduces the commercial value of the disc substrate.

It is an object of the present invention to provide a method of molding a disk substrate, in which the stamper is not deformed and the disk substrate is not defective in appearance.

[0008]

The gist of the present invention is to provide an injection step of injecting a molten resin into a cavity formed of at least two molds, which is provided with a gas flow path for inflowing and / or discharging gas. In a disk substrate injection molding method including a cooling step of molding the disk substrate by cooling the molten resin after transferring the information on the stamper attached to one of the molds, a metal plate without a stamper attached. Pressure A in the gas flow path provided in the mold and pressure B in the gas flow path provided in the mold with the stamper attached
However, there is a relationship of A> B in all of the injection steps, and a relationship of B> A in all of the cooling steps and / or part thereof. Is.

[0009]

The pressure A in the gas flow passage provided in the die without the stamper and the pressure B in the gas flow passage provided in the die with the stamper are poured into the cavity. By setting A> B in all the steps of the injection process, the molten resin presses the stamper, and the stamper comes into close contact with the mold to which the stamper is attached. Therefore, even if the molten resin poured into the cavity pushes the stamper in the direction of the flow, no bending occurs.

Further, all and / or part of the cooling step of cooling the molten resin poured into the cavity has a relation of B> A. When the molten resin is cooled to form the disk substrate, the molten resin shrinks and tries to separate from the stamper. However, when B> A, the stamper is pushed toward the disk substrate and the stamper and the disk substrate come into close contact with each other. .. For this reason, the cooling rates of the respective parts of the disk substrate to be molded are substantially the same, so that the surface of the disk substrate does not become uneven and so-called defective appearance does not occur.

[0011]

EXAMPLES Examples will be described below, but the present invention is not limited thereto. FIG. 1 is a sectional view of an essential part of an embodiment of a disk substrate molding die used in the present invention. In particular, FIG. 1 shows a state immediately after the molten resin is poured into the disk substrate molding die.

The disk substrate molding die of this embodiment includes a stamper 30, a movable die 40 to which the stamper 30 is attached,
It is composed of a fixed mold 10. The movable mold 40 is moved to the fixed mold 10 by a movable device (not shown) to form a cavity. A resin flow path 11 for pouring the molten resin 20 into the fixed mold 10 from an injection unit (not shown).
And a fixed-side gas flow path 12 for inflowing and / or exhausting gas.

The movable mold 40 includes an outer peripheral holder 41 for pressing the outer peripheral portion of the stamper 30, an inner peripheral holder 42 for pressing the inner peripheral portion of the stamper 30, a punch core 43 for punching out the inner diameter of a disk substrate to be manufactured, and a punch air sleeve. 44, a movable-side outer peripheral gas passage 45, and a movable-side inner peripheral gas passage 46.

In this embodiment, the stationary gas passage 12, the movable outer peripheral gas passage 45, and the movable inner peripheral gas passage 46.
, Each of which has two gas flow paths provided symmetrically,
It is not limited to this, for example, four may be provided at a right angle, or may be provided in a circumferential shape. That is, the number of gas channels is not particularly limited and can be arbitrarily changed depending on the area of the opening of the gas channel.

The stationary gas passage 12 can be connected to a pressurizing pump 70 for increasing the pressure of the cavity via the electromagnetic valve 50 and the pressure reducing valve 60. The pressure reducing valve 60 keeps the pressure of the air flowing into the fixed side gas passage 12 constant. Further, the fixed gas flow path 12 can be connected to the decompression pump 80 that lowers the pressure of the cavity via the electromagnetic valve 51.

On the other hand, the movable-side outer peripheral gas passage 45 and the movable-side inner peripheral gas passage 46 can be connected to a pressurizing pump 70 which raises the pressure of the cavity via an electromagnetic valve 52 and a pressure reducing valve 61. The pressure reducing valve 61 keeps the pressure of air flowing into the movable-side outer peripheral air passage 45 and the movable-side inner peripheral gas passage 46 constant. Further, the movable-side outer peripheral air passage 45 and the movable-side inner peripheral gas passage 46 can be connected to a decompression pump 81 that lowers the pressure of the cavity via the electromagnetic valve 53.

During the injection process in which the molten resin 20 is being poured into the cavity from the resin flow passage 11, the pressure A in the fixed side gas flow passage 12 provided in the fixed mold 10 without the stamper 30 and the stamper 30. The pressure B in the movable-side inner peripheral gas flow passage 45 and the movable-side outer peripheral gas flow passage 46 provided in the movable mold 40 additionally provided with A has a relationship of A> B.

In order to achieve the above relationship, the fixed side gas flow path 12 passes through the electromagnetic valve 50 and the pressure reducing valve 60, and then the pressurizing pump 70.
The air is flown in by connecting with, and the pressure A of the fixed side gas flow path 12 is increased. Further, the movable side outer peripheral gas passage 45 and the movable inner peripheral gas passage 46 are connected to the solenoid valve 53.
The air is extracted by connecting to the decompression pump 81 via the pressure reducing pump 81 to reduce the pressure B in the movable-side outer peripheral gas passage 45 and the movable-side inner peripheral gas passage 46.

The molten resin 20 filled in the cavity is
The inner diameter is punched out during the cooling process. As the molten resin 20 cools, it shrinks to form a disk substrate.

In the present invention, all the cooling steps and / or a part thereof are in the relation of B> A. The time when a part of the cooling step is B> A may be any of the first half, the middle half and the second half of the cooling step, but the middle half and the latter half when the molten resin 20 cools and shrinks is preferable.

In order to satisfy B> A, the fixed side gas flow path 1
2 is connected to the decompression pump 80 via the solenoid valve 51 to extract air and reduce the pressure A in the fixed side gas passage 12. Further, by connecting the movable-side outer peripheral gas flow path 45 and the movable-side inner peripheral gas flow path 46 to the pressurizing pump 70 via the electromagnetic valve 52 and the pressure reducing valve 61, air is flowed in, and the movable-side outer peripheral gas flow. The pressure B in the passage 45 and the movable-side inner peripheral gas passage 46 is increased.

FIG. 2 shows the pressure A of the fixed side gas flow path 12, the movable side outer peripheral gas flow path 45 and the movable side inner circumference when the disk substrate is molded using the disk substrate molding die described in FIG. It is a figure which shows one Example of the change of the differential pressure (AB) with the pressure B of the partial gas flow path 46. The abscissa indicates the passage of time, and the ordinate indicates the differential pressure (AB). P1 is the pressure difference (A-B) when A> B, and P2 is the pressure difference (A-) when B> A.
B).

Further, each step of manufacturing the disk substrate is additionally shown in the upper part of FIG. The manufacturing process of the disk substrate is a mold clamping process for clamping the mold to form a cavity, an injection process for pouring molten resin into the cavity, a cooling process for cooling the molten resin, a mold opening process for opening the mold, and a disk substrate formed in the cavity. The process consists of taking out

In this embodiment, a part of the mold clamping process, the injection process and the cooling process has a relation of A> B, and a remaining part of the cooling process has a relation of B> A with the mold opening process. The take-out process has a relation of A> B.

P1 is 0.98 kg / cm ² or more, 9.8
It is preferably less than Kg / cm ² . If it is less than 0.98 Kg / cm ² , a sufficient stamper bending prevention effect cannot be obtained.
When the pressure is 9.8 Kg / cm ² or more, the gas pressure generated in the molten resin at the time of injection is liquefied and remains due to an increase in the atmospheric pressure in the cavity.

P2 is -196 Kg / cm ² or more, -0.
It is preferably less than 98 Kg / cm ² . -0.98 Kg / c
At m ² or more, the disc substrate does not adhere to the stamper, so that a sufficient appearance defect effect cannot be obtained. -196 Kg /
If it is less than cm ² , the stamper is deformed at a position held by the outer peripheral holder 41 and the inner peripheral holder 42.

As described above, the pressure A of the fixed side gas flow path 12 and the pressure B of the movable side outer circumference gas flow path 45 and the movable side inner circumference gas flow path 46 are A in all the injection steps. > B, the stamper 30 is moved to the movable mold 40.
Even if the molten resin 20 is pressed against the movable mold 40 and the molten resin 20 is poured into the cavity, the stamper 30 does not bend.

Further, in all and / or part of the cooling step, by setting B> A, even if the molten resin 20 filled in the cavity is contracted in the cooling step, the stamper 30 is molded. The disk substrate that is pressed against the substrate and is molded is in close contact with the stamper 30. Therefore, the cooling rates of the respective parts of the molded disk substrate are substantially the same, and the appearance of the disk substrate does not deteriorate.

In the disk substrate molding die used in the molding method of the present invention, the fixed die, the movable die and the outer peripheral holder are provided with heating means to cool the outer peripheral side and the inner peripheral side of the disc substrate. It is preferred that the speeds be similar.
Further, when a cooling means for cooling the sprue formed in the cavity is provided, it is preferable to provide a heating means for heating the disk substrate cooled by the cooling means.

[0030]

As described above, in the disk substrate injection molding method of the present invention, since the stamper does not bend during the injection process, the stamper does not deform even if it is repeatedly used. Further, during the cooling process, the molded disc substrate does not peel off from the stamper, and the disc substrate does not have a defective appearance.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a main part of an embodiment of a disk substrate molding die used in a molding method of the present invention and a diagram showing a gas flow passage piping system for inflowing and / or discharging gas.

FIG. 2 is a diagram showing changes in pressure in a gas flow path provided in the disk substrate molding die shown in FIG.

FIG. 3 is a diagram showing a state of an injection process of a disk substrate molding die used in a conventional molding method.

FIG. 4 is a diagram showing a state of a cooling process of a disk substrate molding die used in a conventional molding method.

[Explanation of symbols]

 10 Fixed Mold 11 Resin Flow Path 12 Fixed Side Gas Flow Path 20 Molten Resin 30 Stamper 40 Movable Mold 45 Movable Side Outer Part Gas Flow Path 46 Movable Side Inner Part Gas Flow Path 50 Electromagnetic Valve 60 Pressure Reduction Valve 70 Pressure Pump 80 decompression pump 81 decompression pump

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[Procedure amendment]

[Submission date] February 25, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] 0025

[Correction method] Change

[Correction content]

P1 is 0.1 Kgf / cm ² <P1 <1K
gf / cm ² is preferred. If it is less than 0.1 Kgf / cm ² , sufficient stamper flexure preventing effect cannot be obtained. 1 kg
At f / cm ² or higher, the pressure in the cavity rises,
The gas component generated from the molten resin during injection is liquefied and remains.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0026

[Correction method] Change

[Correction content]

P2 is -20 Kgf / cm ² <P2 <-
0.1 Kgf / cm ² is preferable. -0.1 Kgf / c
At m ² or more, the disc substrate does not adhere to the stamper, so that a sufficient effect of improving the appearance defect cannot be obtained. -20Kg
When it is less than f / cm ² , the stamper is deformed at a portion pressed by the outer peripheral holder 41 and the inner peripheral holder 42.

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Claims (1)

[Claims] 1. An injection step of pouring a molten resin into a cavity composed of at least two molds, and after transferring information on a stamper attached to one of the molds, cooling the molten resin. In a method of molding a disk substrate, which includes a cooling step of molding the disk substrate, a pressure A in a gas flow path provided in a mold not provided with a stamper and a mold provided with a stamper are provided. The pressure B in the gas flow passage is A> in all the injection steps.
A method of molding a disk substrate, wherein the relationship B is satisfied, and further, the relationship of B> A is satisfied in all the cooling steps and / or part thereof.