JPH08156059A - Device and method for injection-molding optical disk - Google Patents

Abstract

PURPOSE: To realize high density molding of an optical disk and prevent a warping after being removed from a mold assembly and a strain from developing in the optical disk by a method wherein a changing-over means between the connecting piping systems of two temperature controlling means to the mold assembly is provided. CONSTITUTION: The device is equipped with a mold assembly 10 for molding an optical disk by injecting a resin in a mold and a first temperature controlling means 20 for setting a first mold cavity temperature by supplying temperature controlling medium 4b to the mold assembly 10. In addition, the device is equipped with a second temperature controlling means 30 for setting a second mold cavity temperature by supplying temperature controlling medium 4b to the mold assembly 10. Further, the device is equipped with a changing-over means 42 for changing-over the connection between the connecting piping system 70 of the first temperature controlling means 20 and the mold assembly 10 and that between the connecting piping system of the second temperature controlling means 30 and the mold assembly. The temperature of the medium 4b supplied from the first temperature controlling means 20 is preferably higher than that of the medium 4b supplied from the second temperature controlling means 30.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disk injection molding, and more particularly to an optical disk injection molding apparatus and an optical disk injection molding method which are optimum for molding a high density optical disk.

[0002]

2. Description of the Related Art When molding an optical disk such as a compact disk (CD), an optical disk injection molding apparatus as shown in FIG. 3 is used. Mold 1 of FIG.
A stamper 6 is arranged between the two. As shown in FIG. 4, the stamper 6 has a protrusion 6a formed on the side of the optical disc D to be molded. On one of the molds 1, a gate 3 for putting the molten resin into the cavity C is formed. A mold temperature controller 4 is connected to the molds 1 and 2 via a pipe 5. This mold temperature controller 4 comprises a tank 4 containing a pump 4a and a temperature control medium 4b.
have c. By operating this pump 4a, the temperature control medium 4b is fed from the mold temperature controller 4 to the pipe 5
It is introduced into the molds 1 and 2 through the pipe and returned to the tank 4c through the pipe 5.

In such a conventional injection molding apparatus, one mold temperature controller 4 is used to set the temperatures of the pair of molds 1 and 2. That is, a pair of dies 1 and 2
In the cavity C of the disc, the temperature of the signal area portion of the optical disc to be molded is one type of fixed set temperature by the temperature control medium 4b of the mold temperature controller 4, and It is designed to keep the surface at a certain temperature. Such a conventional injection molding apparatus is an effective method for molding an optical disc of a format in which a predetermined signal can be obtained even if the time for each cycle of the molding operation is short.

[0004]

However, in order to increase the number of signals to be recorded on the optical disc, when a format is formed on the disc which requires a smaller pit shape and a smaller birefringence or warpage. Is limited in the above-mentioned conventional injection molding apparatus. That is,
In order to accurately transfer smaller pits, it is necessary to further enhance the fluidity of the molten resin when injecting the molten resin into the cavity C. Therefore, it is necessary to raise the temperature of the molten resin and further raise the surface temperature of the cavity C in the mold. As for the temperature of the molten resin, the temperature that the resin can withstand is determined and the fluidity is naturally limited. Therefore, as the next best measure, the temperature of the surface of the cavity C is increased to impede the fluidity of the molten resin. However, if the cavity temperature is high, the temperature when the disk D is taken out will also be high. Therefore, after taking out the molded optical disc, the optical disc may warp or generate distortion in the process of cooling to room temperature, which requires extremely careful handling of the optical disc and is practical. Not.

Therefore, the present invention has been made to solve the above-mentioned problems, and it is possible to perform high density molding of an optical disc, and to prevent warping of the optical disc and distortion in the optical disc after the molded optical disc is taken out. An object of the present invention is to provide an injection molding apparatus for an optical disc and an injection molding method for an optical disc, which can prevent the above.

[0006]

According to the invention as set forth in claim 1, the above object is to provide a mold apparatus for injecting a resin into a mold to mold an optical disk, and to the mold apparatus. A first temperature adjusting means for supplying a temperature adjusting medium to set a first mold cavity temperature, and a second temperature supplying means for supplying a temperature adjusting medium to the mold device. A second temperature adjusting means for setting a mold cavity temperature, a connection piping system of the first temperature adjusting means and a connection piping system of the second temperature adjusting means are connected to the mold device. This is achieved by an optical disk injection molding apparatus including switching means for switching. In the invention according to claim 2, preferably, the temperature of the temperature adjusting medium supplied from the first temperature adjusting means is the same as that of the temperature adjusting medium supplied from the second temperature adjusting means. Higher than temperature. In the invention according to claim 3, preferably, the glass transition temperature of the resin for injecting the resin into the cavity is set by the temperature adjusting medium supplied from the first temperature adjusting means, By the temperature adjusting medium supplied from the second temperature adjusting means,
In order to solidify the resin, the temperature is set lower than the glass transition temperature of the resin. In the invention according to claim 4, preferably, the medium for temperature control is a liquid. According to a fifth aspect of the present invention, when the resin is injected into the cavity of the mold apparatus, the temperature adjusting medium is supplied from the first temperature adjusting means to the mold apparatus, and the mold apparatus is used. A step of setting a first mold cavity temperature in the mold device; and a step of supplying a temperature control medium to the mold device from a second temperature control means when the resin is solidified, And the step of setting the mold cavity temperature of 2).
In the invention according to claim 6, preferably, the temperature of the temperature control medium supplied from the first temperature control means is a glass transition temperature of the resin for injecting the resin into a cavity, The temperature of the temperature control medium supplied from the second temperature control means is lower than the glass transition temperature of the resin in order to solidify the resin.

[0007]

According to the above construction, in the invention described in claim 1, the mold device injects resin into the mold to mold the optical disk. During this molding, the first temperature adjusting means supplies the temperature adjusting medium to the mold device to set the first mold cavity temperature. The second temperature control means is
A second mold cavity temperature is set by supplying a temperature control medium to the mold device. By changing the temperature when the resin is injected into the mold and when the resin is solidified, it is possible to prevent warping of the optical disc and distortion in the optical disc after the molded optical disc is taken out. When the first temperature adjusting means supplies the temperature adjusting medium to the mold device to set the first mold cavity temperature,
The connection piping system of the first temperature control means is connected to the mold device. Then, the second temperature adjusting means supplies a medium for temperature adjustment to the mold device and operates the switching means when setting the second mold cavity temperature,
The connection piping system of the second temperature adjusting means is connected to the mold device. In the invention according to claim 2, preferably, the temperature of the temperature adjusting medium supplied from the first temperature adjusting means is higher than the temperature of the temperature adjusting medium supplied from the second temperature adjusting means. In the invention according to claim 3, which is set high, preferably, the glass transition temperature of the resin for injecting the resin into the cavity is set by the temperature adjusting medium supplied from the first temperature adjusting means. The temperature adjusting medium supplied from the second temperature adjusting means sets the temperature lower than the glass transition temperature of the resin in order to solidify the resin. According to the invention of claim 5,
When the resin is injected into the cavity of the mold apparatus, the temperature adjusting medium is supplied from the first temperature adjusting means to the mold apparatus to set the mold apparatus at the first mold cavity temperature.
When the resin is solidified, the temperature adjusting medium is supplied from the second temperature adjusting means to the mold device, and the mold device sets the second mold cavity temperature. When injecting resin into the mold,
By changing the temperature when the resin is solidified, it is possible to prevent warping of the optical disc and distortion in the optical disc after the molded optical disc is taken out. In the invention according to claim 6, preferably, the temperature of the temperature control medium supplied from the first temperature control means is the glass transition temperature of the resin for injecting the resin into the cavity, and the second temperature control The temperature of the temperature control medium supplied from the means is lower than the glass transition temperature of the resin in order to solidify the resin.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described in detail below with reference to the accompanying drawings. The examples described below are
Since it is a preferred specific example of the present invention, various technically preferable limitations are attached, but the scope of the present invention is, unless otherwise stated to limit the present invention, in the following description.
It is not limited to these modes.

FIG. 1 shows a preferred embodiment of the optical disk injection molding apparatus of the present invention. In FIG. 1, a mold 10, a first mold temperature controller 20, a second mold temperature controller 30, a connecting piping system 70, a switching means 42, and a control means 80 are provided. The mold device 10 has a first mold 12, a second mold 14, and a stamper 6. The stamper 6 is formed so that a protrusion 6a as shown in FIG. 4 projects toward the optical disc D to be molded. The first mold 12 includes a gate 63, a cavity C,
And a temperature control medium circulation passage 60. The second mold 14 has a temperature control medium circulation passage 60.
The stamper 6 is sandwiched between the first die 12 and the second die 14. Molten resin is supplied to the gate 63 in the arrow X direction.

The first mold temperature controller 20 and the second mold temperature controller 30 have the same structure. The first mold temperature controller 20 and the second mold temperature controller 30 include the pump 4
a, a tank 4c, and a liquid 4b, which is a temperature adjusting medium contained in the tank 4c. Tank 4
The liquid 4b for controlling the temperature in c is the heating element 4 such as a coil.
It is heated to a predetermined temperature by d. The pump 4a of the first mold temperature controller 20 can supply the heated liquid 4b to the temperature control medium circulation passage 60 of the first mold 12 via the connection piping system 70. ing. Similarly,
The pump 4a of the second mold temperature controller 30 supplies the heated liquid 4b to the second mold 14 via the connection piping system 70.
The temperature control medium circulation passage 60 can be supplied. This connection piping system 70 includes piping 46, 47,
It has 48, 49, 50 and 51.

The pipe 46 is connected to the pipe 4 via the connecting portion 40.
7 and 48, and the pipe 47 is connected to the tank 4c of the first mold temperature controller 20. Piping 48
Is connected to the tank 4c of the second mold temperature controller 30. Piping 49 from the first mold temperature controller 20,
The pipe 50 from the second mold temperature controller 30 can be switched by the switching means 42. The switching means 42 such as a switching valve includes a first mold 12 and a second mold 12 via a pipe 51 and a connecting portion 44.
The mold 14 is connected to the temperature control medium circulation passage 60. The temperature control medium circulation passage 60 is connected to the pipe 46 via the connecting portion 48. In this way, a circulation circuit for the temperature control medium is formed.

The temperature control medium is preferably a liquid such as water or oil. First mold temperature controller 20
Allows the first mold cavity temperature T1 ° C. to be set for the cavity C. This first mold temperature controller 20 raises the temperature T1 ° C. of the first mold 12 and the second mold 14 when the molten resin is injected into the cavity C to the glass transition point TG of the resin. Have the ability to

On the other hand, the second mold temperature controller 30
Has the ability to lower the optical disk take-out temperature T2 ° C. below the glass transition point TG of the mold temperature T1 ° C. when the molten resin is solidified in the cavity C. Examples of the molten resin include polycarbonate, PMMA (polymethylmethacrylate), APO
(Amorphous poly olefin) or the like can be adopted.

Next, an injection molding method by the operation of the above-mentioned optical disk injection molding apparatus will be described. Molten resin is injected into the cavities C of the first mold 12 and the second mold 14 of FIG. 1 through the gate 63. In this way, when the molten resin is injected into the cavity C, the surface temperature of the cavity 8 is raised so as not to impair the fluidity of the molten resin, so that fine pits can be molded from the stamper 6. Can be transferred to.

Therefore, in this case, the switching means 42
By operating the first mold temperature controller 20 from the first mold temperature controller 20 side to the first mold 12 and the second mold 12 via the pipe 49 and the switching means 42, and the pipe 51 and the connecting portion 44.
It is supplied to the temperature control medium circulation passage 60 of the mold 14. The medium sent from the first mold temperature controller 20 to the temperature control medium circulation passage 60 raises the mold temperature T1 ° C. at the time of injection to the glass transition point TG of the molten resin,
The signal of the master (stamper) 6 can be transferred to the molten resin more accurately.

Next, when the molten resin is solidified in the cavity C, it is necessary to lower the temperature to a take-out temperature T2 ° C. of the optical disk which is below the glass transition point TG of the mold temperature T1 ° C. Therefore, the control means 80 controls the first mold temperature controller 20.
Instead, the second mold temperature controller 30 is operated, and the switching valve 42 is switched to the second mold temperature controller 30 side. As a result, the temperature control medium 4b of the second mold temperature controller 30 is connected to the pipe 50, the switching means 42 and the pipe 5.
1 and is introduced into the temperature control medium circulation passage 60 via the connection portion 44. As a result, the molten resin is solidified in the cavity C, so that distortion in the molded disk can be reduced, and birefringence and warpage can be reduced.

In this way, by operating the first mold temperature controller 20 and the second mold temperature controller 30 alternately by the command of the control means 80, in the cavity C of the molds 12 and 14. By injecting the molten resin and solidifying the molten resin, a high density optical disc can be created.

FIG. 2 shows the injection timing of this molten resin, the surface temperature of the mold cavity C, and changes in the temperatures of the first mold temperature controller 20 and the second mold temperature controller 30. . Timing signal TP indicating injection timing
Represents the injection time. This injection timing signal T
Corresponding to the trailing edge of P, the first mold temperature controller 2
The timing of switching between 0 and the second mold temperature controller 30 is obtained. Switching between the first mold temperature controller 20 and the second mold temperature controller 30 is performed by the switching means 4 of FIG.
It does by 2. The temperature of the mold cavity C in FIG. 1 is synchronized with the injection timing signal TP indicating the injection time, and is taken out from the glass transition point TG (corresponding to the temperature T1 ° C) at the extraction temperature T.
It varies between 2 ° C. The first mold temperature controller 20,
When the molten resin is injected into the cavity C, the temperature control medium 4 is adjusted so that the surface temperature of the cavity C becomes the temperature T1 ° C.
Time TF for supplying b and ejecting the molded optical disc
Immediately after completion of the above, the first mold temperature controller 20 is operated to supply the temperature control medium 4b.

Similarly, the second mold temperature controller 30
Is immediately activated at the trailing edge of the injection timing signal TP representing this injection time. Actually, it takes time to transfer heat from the temperature control medium circulation passage (also referred to as a groove of the temperature control liquid) in FIG. 1 to the surface of the cavity C. The switching timing is advanced.

As described above, in the embodiment of the present invention, it is possible to avoid the deterioration of the properties of the molten resin by changing the mold surface temperature by using the two mold temperature controllers 20 and 30. When the resin is injected into the mold, the surface temperature of the cavity in the mold is increased so that the fluidity of the molten resin is not impaired. Therefore, fine pits can be formed in the molded disc. Further, by temporarily reducing the cavity surface temperature in the mold from the time when the injection is completed, the resin is solidified without leaving any distortion inside the disk. Therefore, there is an advantage that no special consideration such as annealing is required for the optical disc even after taking out the molded optical disc.

However, the present invention is not limited to the above embodiment. In the embodiment described above, the temperature adjusting liquid is used as the temperature adjusting medium, but the temperature adjusting medium is not limited to this, and other types of temperature adjusting medium can be used. As the type of optical disc that can be molded, a compact disc, a magneto-optical disc, a laser disc, or the like can be injection-molded.

[0022]

As described above, according to the present invention, it is possible to form an optical disc with a high density and to prevent the optical disc from warping or being distorted after taking out the formed optical disc. it can.

[Brief description of drawings]

FIG. 1 is a diagram showing a preferred embodiment of an optical disk injection molding apparatus of the present invention.

FIG. 2 is a diagram showing a temperature switching timing in the injection molding apparatus of FIG.

FIG. 3 is a diagram showing a conventional optical disk injection molding apparatus.

FIG. 4 is a sectional view showing a part of a molded optical disc and a stamper.

[Explanation of symbols]

 8 Cavity 10 Mold Device 12 First Mold 14 Second Mold 20 First Mold Temperature Controller 30 Second Mold Temperature Controller 42 Switching Means 60 Temperature Control Medium Circulation Passage 70 Connection Piping System 80 Control means

Claims (6)

[Claims] 1. A mold device for injecting a resin into a mold to mold an optical disk, and a medium for temperature control is supplied to the mold device to set a first mold cavity temperature. Temperature adjusting means for supplying a temperature adjusting medium to the mold device to set a second mold cavity temperature, and the mold. An optical disk injection molding apparatus, comprising: a switching means for switching connection of a connection piping system of the first temperature adjusting means and connection of a connection piping system of the second temperature adjusting means to the apparatus. 2. The temperature of the temperature adjusting medium supplied from the first temperature adjusting means is higher than the temperature of the temperature adjusting medium supplied from the second temperature adjusting means. 1. An optical disk injection molding apparatus according to item 1. 3. The glass transition temperature of the resin for injecting the resin into the cavity is set by the temperature adjusting medium supplied from the first temperature adjusting means, and the second temperature adjusting is performed. The optical disk injection molding apparatus according to claim 2, wherein a temperature lower than a glass transition temperature of the resin is set to solidify the resin by the temperature adjusting medium supplied from the means. 4. The injection molding apparatus for an optical disc according to claim 1, wherein the temperature adjusting medium is a liquid. 5. When the resin is injected into the cavity of the mold device, a medium for temperature control is supplied from the first temperature control means to the mold device, and the mold device is moved to the first mold. A step of setting a mold cavity temperature; and a step of supplying a temperature control medium from a second temperature control means to the mold device so that the mold device controls the second mold cavity temperature when the resin is solidified. An injection molding method for an optical disc, comprising: a setting step. 6. The temperature of the temperature control medium supplied from the first temperature control means is a glass transition temperature of the resin for injecting the resin into a cavity, and the second temperature control means. The method of injection molding an optical disc according to claim 5, wherein the temperature of the temperature control medium supplied from the temperature control medium is lower than the glass transition temperature of the resin in order to solidify the resin.