JPH08216217A - Die for molding optical disc substrate and system thereof as well as molding method - Google Patents

Abstract

PURPOSE: To shorten a molding cycle by cutting a cooling time with a concurrent action to maintain high transfer property. CONSTITUTION: A temperature adjustment groove 3 for heating and a temperature adjustment groove 4 for cooling are provided in a mirror plane block which is installed on a fixed de 1 and a movable die 2 respectively. Further, the groove 3 and the groove 4 are alternately arranged across an area from an inner periphery to an outer periphery. At the same time, in order to chance the transfer property of the outer peripheral part, so many temperature adjustment groove 3 for heating are densely arranged. Thus the temperature adjustment grooves which are independently working for both cooling and heating purposes, are provided in the mirror plane block 5. In addition, temperature adjustment media whose discharge pressure is controlled by synchronizing the temperature adjustment grooves to the molding cycle of a molding machine, are caused to circulate for molding. Consequently, a die capable of molding a substrate with high transfer property and excellent face uniformity can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mold for molding an optical disk substrate, a system therefor, and a molding method, and more specifically, an optical disk substrate for molding a rewritable type, a write-once type or a read-only type optical disc substrate by an injection molding method. The present invention relates to a molding die, a system therefor, and a molding method.

[0002]

2. Description of the Related Art As a known document describing a conventional optical disk substrate molding die, for example, Japanese Patent Laid-Open No. 2-1
There is a "mold for injection molding and a method for molding a disk substrate using the mold" in Japanese Patent No. 60525. In this publication, the temperature control means independent of the vicinity of the gate portion is provided in the vicinity of the outer periphery of the sprue to improve the optical characteristics and mechanical characteristics of the molded product and shorten the molding cycle. In the sprue bush near the gate portion, a first annular heat medium flow passage that is a first temperature control means for cooling is formed so as to surround the outer periphery of the sprue in the sprue bush located away from the gate portion. Second for heat retention
The second annular heat transfer medium flow path, which is the temperature control means, is formed. The first temperature control means cools the outer circumference of the sprue,
The second temperature control means independently performs different temperature control such as keeping the temperature near the gate portion. As a result, the injected resin fills the cavity without being cooled at the gate, so the temperature distribution of the resin on the inner and outer peripheries of the substrate becomes uniform, and a substrate with good optical and mechanical properties is obtained. It is what is done. That is, the temperature unevenness in the cavity is suppressed.

Further, in Japanese Patent Laid-Open No. 5-318545, "Molding Method of Disk Substrate", a cooling passage for mold temperature control is provided in order to mold the disk substrate in a high cycle without causing defective molding. In a method of molding a disk substrate in which a molten resin is injected from an injector into a cavity of a mold 1 to be cooled and solidified, a flow of cooling water in a cooling passage is temporarily injected in a step of injecting and holding pressure. Even if the mold temperature is set to a low level, the influence of the mold temperature can be avoided in the injection and pressure-holding steps to prevent the fluidity of the molten resin from decreasing. That is, the flow of cooling water is stopped in the injection and pressure-holding steps to maintain the resin fluidity in the cavity.

Further, in Japanese Unexamined Patent Publication No. 61-252122, "Mold temperature controlling method and mold temperature controlling apparatus for manufacturing a disk substrate", a flow of a cooling medium is branched from a main flow path in synchronization with a molding cycle. In order to obtain molding conditions with good transferability without residual strain by switching to the path, the mold temperature controller for disk substrate manufacturing attached to the injection molding machine is connected to the main flow path of the cooling medium from the switching valve. A branch flow path is provided, which is composed of a branch pipe and a check valve. Immediately before the mold clamping that forms the cavity ends and injection begins, the switching valve is activated by the signal from the injection molding machine, the flow path of the cooling medium is switched from the main flow path to the branch flow path, and the fluid is passed through the mold fluid passage hole. Is stopped, the resin material is injected into the cavity, and is kept stopped until the internal pressure of the resin rises sufficiently. Therefore, the cooling rate of the resin material in the cavity is slowed down, the solidification of the skin layer is delayed, the transferability is improved, the residual strain is reduced, and the birefringence is improved. That is, in order to maintain the fluidity of the resin in the cavity, the mold temperature control circuit is switched to the in-mold / out-mold branch circuit in synchronization with the molding process.

[0005]

As described above, in the conventional optical disk substrate molding die and its molding method,
According to the reference, the circuit for controlling the temperature inside the cavity is the same as that of the conventional technique only by providing an independent heating / cooling circuit only in the vicinity of the sprue filled with the resin in the cavity. That is, the cavity temperature control circuit, which greatly affects the transferability of the information pit and the guide groove, is still the conventional technique.

In the literature, the mold temperature control is stopped at the time of injection and pressure keeping to prevent the deterioration of fluidity due to a low mold temperature. However, it is not possible to positively add heat and cooling to the mold. I haven't. That is, actively heating the cavity /
Not cooled. Further, since the flow of cooling water is temporarily stopped, the responsiveness deteriorates, and a heat storage effect due to the heat of the resin occurs in the mold, cooling efficiency in the cooling process decreases, and the molding cycle shortening effect is small. .

Further, in the literature, the temperature control circuit is switched while the resin is filled in the cavity to stop the flow of the temperature control water in the cavity temperature control groove to lower the temperature of the inner wall surface of the cavity and thereby Prevents deterioration of resin fluidity,
The mold is not actively heated and cooled.
That is, the cavity is not actively heated / cooled. In addition, the flow of cooling water in the mold is temporarily stopped, resulting in poor responsiveness, and the heat storage effect of the heat of the resin is generated in the mold, which lowers the cooling efficiency in the cooling process. The effect of shortening the molding cycle is small.

At present, various types of rewritable, write-once, or read-only optical discs are used as new information recording media. The substrates of these optical disks are usually molded in a mold by an injection molding method. In order to increase the production efficiency of the optical disk substrate and reduce the production cost by this method, it is essential to shorten the molding cycle. For that purpose, it is necessary to cool the high temperature resin filled in the cavity to a temperature at which it can be taken out of the mold in a short time. In other words, it is necessary to set the cavity temperature control as low as possible and keep the cooling efficiency high.

On the other hand, the optical disk substrate is required to faithfully transfer a pit row and a guide groove for tracking, which are engraved with a very narrow pitch and high density, to the stamper. To obtain such high transferability,
It is necessary to fill the cavity with resin while suppressing the formation of the skin layer and maintaining high fluidity. In other words, set the cavity temperature as high as possible,
It is necessary to keep the resin temperature high.

As described above, there are two contradictory requirements for setting the cavity temperature during optical disk molding.
Moreover, while cost requirements are becoming more stringent and further shortening of the molding cycle is being demanded at present, a new high-density recording method for optical disks is newly proposed.
The requirements for transferability are becoming more stringent.

The present invention has been made in view of such circumstances, and an optical disk molding die and a temperature control system for shortening a cooling time and a molding cycle while maintaining a high transfer property, and It is an object to provide a molding system and an optical disk molding method using them.

[0012]

In order to solve the above-mentioned problems, the present invention provides: (1) In a mold for molding an optical disk substrate by an injection molding method, a mirror surface block is independently used for cavity cooling and heating. And (2) the cooling temperature adjusting grooves and the heating temperature adjusting grooves are alternately arranged, or (3)
It has a temperature sensor for monitoring the temperature of the mold, a thermometer for measuring the temperature of the mold based on a signal from the temperature sensor, and a temperature controller control system for inputting the mold temperature signal from the thermometer. , It is possible to switch the valve that selects the system of the temperature control circuit by a signal from the outside and control the discharge pressure of the temperature control medium from the temperature control device, or (4) above (1) or (2)
In the optical disk substrate molding method using the optical disk substrate molding die described above and the mold temperature control system described in (3) above, a heating temperature control medium is caused to flow into the cooling temperature control groove at the time of starting the molding, or , (5) above (1) or (2)
In the optical disk substrate molding method using the optical disk substrate molding die described above and the mold temperature control system described in (3) above, the circulation of each temperature control medium is controlled in synchronization with the molding step, or (6 ) In an optical disk substrate molding system for molding an optical disk substrate by the optical disk substrate molding method described in (5), the cavity temperature is monitored during molding, and the temperature control system is controlled according to the cavity temperature simultaneously with the molding process. It is a feature.

[0013]

With the optical disk substrate molding die, system and molding method of the present invention having the above-described structure, (1) the mirror surface block has independent temperature control grooves for cooling and heating. It is possible to obtain a mold capable of forming a substrate having high property and excellent in-plane uniformity. Further, it is possible to realize a mold having a structure for simultaneously satisfying the contradictory requirements of resin filling while maintaining high cooling efficiency and high fluidity. (2) Since the cooling and heating temperature control are controlled in synchronization with the molding process using the mold of (1), the molding cycle can be shortened while maintaining high transferability. Further, it is possible to realize a mold having a structure that makes it easier to control the temperature of each part in the cavity. (3) By using the mold of (1) above, the heating medium is caused to flow also through the cooling temperature control groove at the time of molding start-up, so that the molding start-up time can be shortened. Further, it is possible to realize a mold temperature control system capable of performing optimum temperature control in synchronization with each cycle of the molding process and between each molding cycle from the start of molding to the continuous molding.

(4) In the mold of (1) above, since the cooling temperature adjusting grooves and the heating temperature adjusting grooves are alternately arranged,
The effects of cooling and heating temperature control performed in separate systems are uniform in each part in the plane. Further, it is possible to realize a molding method that shortens the time required from the start of molding to the stabilization of the mold temperature. (5) It is possible to control the discharge pressure from the discharge motor of the temperature control medium by a signal from the outside, and it is possible to switch the valve that selects the temperature control circuit system, so that the optimum temperature control is performed in synchronization with the molding process. You can Further, it is possible to realize a molding method in which optimum mold temperature control is performed in synchronization with the molding process and the molding cycle is shortened while maintaining high transferability. (6) Good transferability and substrate characteristics, since the mold has the mold of (1) or (4) and the temperature controller groove of (5), and molding is performed while temperature control is synchronized with the molding process. It is possible to mold a substrate that maintains the above in a short molding cycle. Further, it is possible to realize an optical disk substrate molding system that facilitates the switching from the molding start-up to the production start and improves the stability of the optical disk substrate quality during production.

[0015]

Embodiments will be described below with reference to the drawings. FIG. 1 is a configuration diagram for explaining an embodiment of a mold for molding an optical disk substrate and a system therefor according to the present invention, and is an enlarged view showing a mold portion of a molding system in a cross section. In the figure, 1 is a fixed mold, 2 is a movable mold, 3 is a temperature control groove for heating, 4 is a temperature control groove for cooling, 5 is a mirror surface block, 6 is a temperature control medium for heating, and 7 is a temperature control for cooling. It is a medium.

In FIG. 1, the heating temperature adjusting groove 3 and the cooling temperature adjusting groove 4 are arranged in the mirror surface block 5 such that the cooling temperature adjusting groove 4 and the heating temperature adjusting groove 3 alternate from the inner circumference. However, in the example shown in this figure, the heating temperature adjusting grooves 3 are densely arranged in order to enhance the transferability of the outer peripheral portion.

One cycle of the injection molding process is roughly divided into an injection process of injecting the molten resin into the cavity (after the mold is closed) and a predetermined volume reduction by supplementing the volume reduction caused by the contraction of the resin due to cooling. A pressure-holding process that performs additional resin filling to obtain a shaped molded product, a cooling process that cools the resin filled in the cavity to a temperature at which it can be taken out, and after opening the mold and taking out the molded product It consists of four steps, a mold opening / closing step of closing the mold.

In order to achieve the object of the present invention in the molding of an optical disk substrate, it is desired that the cavity temperature be high in order to obtain high transferability in the resin injection step, while shortening the molding cycle. Shorten the cooling time. That is, the cavity temperature should be lowered as much as possible during the cooling process.

Therefore, the heating temperature adjusting groove 3 is formed in the mirror surface block 6.
As shown in FIG. 2, the cooling pressure control groove 4 and the cooling temperature control groove 4 are respectively circulated, and as shown in FIG. 2, the discharge pressure of the heating temperature control medium from the completion of cooling in the previous cycle to the mold opening / closing process to the injection process to the middle of the pressure holding process. At the same time, the discharge pressure of the cooling temperature control medium is lowered and heat is applied to the cavity to improve transferability. From the middle of the pressure holding process to the completion of the cooling process, conversely, the discharge pressure of the heating temperature control medium is lowered, and at the same time, the discharge pressure of the cooling temperature control medium is increased to remove heat from the cavity and rapidly fill the filling resin. Let it cool. 2 shows the molding 1 of the temperature control system according to the present invention.
The discharge pressure of the heating temperature control medium between cycles is shown by a solid line, the discharge pressure of the cooling temperature control medium is shown by a dotted line, and the mold temperature is shown by a dashed line.

Further, these operations are performed by changing the discharge pressure without stopping the flow of each temperature control medium. Therefore, the response of heating / cooling switching is higher than that of stopping / switching the temperature control system,
Since the heat storage effect generated in the mold by the heat of the resin can be suppressed, the molding cycle can be further shortened. As a result, the molding cycle can be shortened while maintaining good transferability, and the production efficiency can be improved.

Further, in the temperature control system according to the present invention,
By appropriately combining the discharge pressures and temperature settings of the heating / cooling temperature control media, it is possible to set the temperature distribution in the cavity as desired, thereby reducing the internal strain of the optical disk substrate. At the same time, it is possible to improve board quality such as improvement of mechanical characteristics such as warpage. The case described in claim 2, wherein the cooling temperature adjusting groove 4 and the heating temperature adjusting groove 3 are alternately arranged from the inner circumference to the outer circumference,
This is an example where importance is attached to the temperature distribution control in the cavity.

FIG. 3 is a view for explaining the operation of the molding system according to the present invention. In the figure, 11 is a molding machine, 12 is a mold, 13 is a temperature sensor, 14 is a thermometer, and 15 is molding machine control. A system, 16 is a temperature controller control system, 17 is a mold temperature controller (for cooling / heating), and 18 is a temperature control circuit system switching valve. The molding machine control system 15 controls the operation of the molding machine 11, and an operation signal is sent from the molding machine 11 to the molding machine control system 15. The molding machine 11 is provided with a temperature sensor 13 for monitoring the temperature of the die 12, and the temperature of the die is measured by a thermometer 14 according to a detection signal from the temperature sensor 13. A mold temperature signal is obtained and input to the temperature controller control system 16.

On the other hand, a molding machine operation signal from the molding machine control system 15 is also input to the temperature controller control system 16. A discharge pressure control signal and a discharge pressure setting / medium temperature setting control signal are output from the temperature controller control system 16 and input to the mold temperature controller 17. From the mold temperature controller 17, the heating temperature control medium and the cooling temperature control medium flow into the mold 12 via the temperature control circuit system switching valve. The temperature control circuit switching valve 18 is switched by a temperature control circuit switching signal from the temperature controller control system 16.

That is, in order to enhance the effect of the temperature control system described above, the temperature sensor 13 monitors the cavity temperature during molding, and the molding machine 11 controls the signal for switching the discharge pressure according to each step of the molding cycle. Molding is performed while controlling the temperature setting value and discharge pressure setting value of each temperature control medium according to the cavity temperature while sending the temperature control system. Further, at the time of starting the molding, the heating temperature control medium is made to flow also into the cooling temperature control groove 4 until the predetermined cavity temperature is reached.
The temperature control circuit switching valve 18 switches the temperature control circuit. With such a configuration of the molding system, it is possible to suppress the quality variation between the molding disk substrates and to shorten the time required for starting the molding.

[0025]

As is apparent from the above description, the present invention has the following effects. (1) Effect corresponding to claim 1: By providing a heating temperature control groove and a cooling temperature control groove of independent systems respectively, resin filling in a state where high cooling efficiency and high fluidity are maintained It is possible to provide molds that simultaneously satisfy the contradictory requirements. (2) Effect corresponding to claim 2: By providing a structure in which temperature control grooves for heating and cooling temperature control grooves of independent systems are alternately arranged, the temperature control of each part in the cavity is made easier. Can provide mold. (3) Effect corresponding to claim 3: A mold temperature control system capable of performing optimum temperature control in synchronization with one cycle of the molding process and between each molding cycle from molding startup to continuous molding. Can be provided. (4) Effect corresponding to claim 4: By circulating the heating temperature control medium in the cooling temperature control groove at the time of molding startup, the time required from the startup of molding to the stabilization of the mold temperature is shortened. A molding method can be provided. (5) Effect corresponding to claim 5: A molding method for shortening the molding cycle while maintaining high transferability by controlling the heating temperature control system and the cooling temperature control system independently in synchronization with the molding cycle. Can be provided. (6) Effect corresponding to claim 6: In order to perform optimum temperature control by synchronizing with the molding process and simultaneously adjusting to the mold temperature, it is easy to switch from molding start-up to production start, and production It is possible to provide an optical disk substrate molding system in which the stability of the optical disk substrate quality is improved.

[Brief description of drawings]

FIG. 1 is a configuration diagram for explaining an example of a mold part of a molding system according to the present invention.

FIG. 2 is a diagram showing the discharge pressure of the heating temperature control medium, the discharge pressure of the cooling temperature control medium, and the mold temperature during one molding cycle of the temperature control system of the present invention.

FIG. 3 is a diagram showing a control flow of the molding system according to the present invention.

[Explanation of symbols]

1 ... Fixed mold, 2 ... Movable mold, 3 ... Temperature control groove for heating, 4 ...
Cooling temperature control groove, 5 ... Mirror surface block, 6 ... Heating temperature control medium, 7 ... Cooling temperature control medium.

Claims (6)

[Claims] 1. A mold for molding an optical disk substrate by an injection molding method, characterized in that the mirror surface block has temperature control grooves of independent systems for cooling the cavity and for heating, respectively. . 2. The optical disk substrate molding die according to claim 1, wherein the cooling temperature adjusting grooves and the heating temperature adjusting grooves are arranged alternately. 3. A temperature sensor for monitoring the temperature of the mold, a thermometer for measuring the temperature of the mold based on a signal from the temperature sensor, and a temperature controller for inputting the mold temperature signal from the thermometer. A mold temperature control system having a control system, capable of switching valves for selecting a temperature control circuit system by an external signal and controlling discharge pressure of a temperature control medium from a temperature controller. 4. An optical disk substrate molding method using the optical disk substrate molding die according to claim 1 or 2 and the mold temperature control system according to claim 3, wherein the cooling temperature control groove is also heated at the start of molding. A method of molding an optical disk substrate, characterized in that a temperature control medium is flown. 5. An optical disk substrate molding method using the optical disk substrate molding die according to claim 1 or 2 and the mold temperature control system according to claim 3, wherein each temperature control medium is circulated in synchronization with the molding step. A method for molding an optical disk substrate, which comprises controlling 6. An optical disk substrate molding system for molding an optical disk substrate by the optical disk substrate molding method according to claim 5, wherein the cavity temperature is monitored during molding, and the temperature control system is controlled at the same time as the molding step according to the cavity temperature. An optical disk substrate molding system characterized by performing.