JP2003141783A - Mold device for molding optical disk - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mold device for molding an optical disk which prevents the wear of mold bodies by the expansion and shrinkage of a stamper accompanying heating and cooling at every shot and has an excellent heat resistance and durability. SOLUTION: This mold device has the stationary mold (the first mold body) 1 and moving mold (the second mold body) 2 for delineating the cavity space for molding the optical disk by injection molding and is formed by coating a stamper supporting surface 17a formed to fix the stamper 36 to a cavity block 17 of the stationary mold 1 with a cBN film 17b.

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 die for manufacturing an optical disk such as a DVD (digital video disk).

[0002]

2. Description of the Related Art A substrate for an optical disk such as a DVD is generally manufactured by injection molding a resin. An example of a molding die device used for this injection molding is shown in FIG. The molding die apparatus 200 shown in this figure is configured to include a movable die 201 and a fixed die 202 arranged so as to face the movable die 201. The movable die 201 and the fixed die 202 are connected to each other. A space formed by closing the mold is a cavity space C. The surface of the movable die 201 on the cavity space C side is a stamper support surface 201A for supporting the disk-shaped stamper 203. Then, a molten resin as a molding material is filled in the cavity space C,
After the resin in the cavity space, that is, the optical disk is solidified, the fixed mold 202 and the movable mold 201 are opened, and the molded optical disk is taken out. In the cavity space C, the sprue 204 to the sprue 20 are formed on the fixed mold 202 at a position corresponding to the center of the cavity space C.
The resin is injected through a recess (die) 207 formed at the tip of the movable mold 20.
The center of the optical disk formed in the cavity space C by moving the cut punch 205, which is provided at a position facing the die 207 and is movable back and forth, to the fixed die 201 side and enters the die 207. While forming an opening hole in the portion, the resin in the sprue 204 and the resin (optical disk) in the cavity C are cut.

[0003]

The mold apparatus 2 having the above structure
At 00, since the temperature of the resin injected from the sprue 204 is about 350 ° C., the stamper 203 is also heated to about 350 ° C. at the time of resin filling, and then cooled to about 100 ° C. to solidify the resin. The stamper 203 repeats expansion and contraction by such a heating / cooling cycle. On the other hand, the stamper support surface 2
Since 01A is kept at about 100 ° C. or lower to cool and solidify the resin, the temperature does not change greatly between shots. Therefore, the stamper 203 slides on the stamper supporting surface 201A during the operation of the mold apparatus. The stamper supporting surface 201A and the stamper 20 due to the sliding of the stamper 203 as described above.
3 Abrasion powder generated by abrasion of the back surface is stamper 203
When attached to the back surface or the top surface (side surface of cavity C),
The flatness of the stamper 203 may be impaired, or the shape of wear may be transferred to the optical disc, resulting in transfer failure. As a result, there have been problems such as a reduction in product yield and a shortened life of the stamper 203. Therefore, in order to prevent wear of the stamper supporting surface 201A, TiN or DLC (Diamond Like Carbo) is formed on the stamper supporting surface 201A.
Although a mold device in which a thin film of a hard material such as n) is formed has been proposed, in the case of forming a TiN film, the abrasion of the TiN film due to lack of strength poses a problem. Then, peeling of the DLC film due to insufficient adhesion strength of the film has been a problem.

The present invention has been made in order to solve the above-mentioned problems, and prevents wear of the mold body due to expansion and contraction of the stamper due to heating and cooling for each shot, and has excellent heat resistance and durability. It is an object of the present invention to provide an optical disk molding die device including the above.

[0005]

In order to solve the above problems, the present invention is provided with a first mold body and a second mold body that define a cavity space for molding an optical disk by injection molding. A stamper supporting surface for indicating a stamper for forming irregularities on the optical disk is formed on the first mold body or the second mold body, and the stamper supporting surface is formed on the first mold body or the second mold body. Provided is a mold device for optical disk molding, wherein a stamper supporting surface is covered with a cBN film.

The mold apparatus according to the present invention having the above-described structure is a hard thin cBN film on the stamper supporting surface of the mold body.
By forming the (cubic boron nitride) film, it is possible to prevent wear of the mold body due to expansion and contraction of the stamper accompanying heating and cooling for each shot, that is, generation of wear powder due to wear of the mold body and stamper. . Therefore, it is possible to prevent the occurrence of transfer failure due to the abrasion powder, and it is possible to extend the life of the mold body and the stamper. This is because the cBN film is an extremely hard film having a hardness second only to that of diamond, but has excellent sliding characteristics, so that the sliding between the stamper and the stamper supporting surface can be made smoother. Is.

In the optical disk molding die apparatus according to the present invention, the film thickness of the cBN film is 0.2 μm to 4 μm.
The range is preferably The film thickness of the cBN film is 0.
If it is less than 2 μm, the durability of the film is insufficient because it is too thin,
The cBN film and the stamper supporting surface are likely to wear due to expansion and contraction of the stamper due to heating and cooling. When the film thickness exceeds 4 μm, peeling of the film tends to occur due to the stress inherent in the cBN film.

Further, in the above-mentioned optical disk molding die device, it is preferable that the cBN film is formed by a CVD method or a sputtering method.

Next, in the optical disk molding die apparatus according to the present invention, a mold having the stamper supporting surface is provided with a vacuum chuck mechanism for exhausting the back side of the stamper to fix the stamper. Preferably. By providing such a vacuum chuck mechanism, the stamper can be more stably held on the stamper supporting surface, and the gas component entrained with the resin as the molding material and the resin powder obtained by solidifying the gas component to some extent Since it can be discharged to the outside, the maintenance cycle can be extended. Therefore, the operating time of the device can be lengthened and the production efficiency can be improved.

Next, in the optical disk molding die apparatus according to the present invention, the mold body having the stamper supporting surface may be provided with a claw portion for fixing the inner end portion of the stamper. it can. By fixing the inner end of the stamper with such a claw portion, the stamper can be more stably fixed, and burrs can be suppressed from occurring at the boundary between the inner end of the stamper and the mold body that holds the stamper. It is possible to manufacture a high quality optical disc.
Further, by fixing with the claw portion, it is possible to perform the molding in a state where the stamper is surely pressed against the stamper supporting surface of the mold body, so that it is possible to prevent the stamper from rising during molding. That is, it is possible to prevent strong contact between the stamper and the stamper supporting surface by filling the resin with the stamper in a floating state. Therefore, the life of the stamper can be extended also by this action, and the life of the stamper can be further extended in combination with the action of the cBN film formed on the stamper supporting surface.

Next, in the optical disk molding die apparatus according to the present invention, a taper surface is formed on the surfaces of the first mold body and the second mold body which are opposed to each other and which are fitted in a taper when the mold is closed. And a guide pin provided on one of the first mold body and the second mold body and a guide pin of the other mold body, and the guide pin is provided on the mold body. And a guide member having a guide pin receiver slidably fitted in the opening / closing direction.

At the time of molding an optical disk, a pair of mold bodies are closed, and a product cavity formed between these mold bodies is filled with a molding material. After the molding material filled in the product cavity, that is, the optical disk is solidified, both molds are opened and the molded optical disk is taken out. In a state where the two mold bodies are closed, the two molding bodies are centered by the tapered surfaces of the positioning members fixed to the molding bodies being fitted to each other. On the other hand, when the two mold bodies are open, the positioning members of the two mold bodies are separated from each other, but the guide pins and the guide pin receiver into which the guide pins are slidably fitted in the opening and closing directions of the two mold bodies are used to The body is aligned. With such a configuration, since both mold bodies are surely aligned with each other and the resin is filled and molded, the pressure from the resin acting on the stamper can be made uniform,
Combined with the action of the cBN film, the life of the stamper can be further extended.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of an optical disk molding method of the present invention and an optical disk molding die apparatus used in this method will be described below with reference to the drawings. First, the structure of a mold device for molding an optical disk will be described. Reference numeral 1 is a fixed die as a first die body, 2 is a movable die as a second die body, and these fixed die 1 and movable die 2 are the die opening / closing directions (shown by AB in FIG. 1) in FIGS. Direction) to open and close each other to form product cavities (cavity spaces) 3 for forming an optical disk when the mold is closed. In addition, in FIGS. 1, 2 and 4, the fixed mold 1 and the movable mold 2 are shown in the vertical direction in the drawing (shown as AB in FIG.
However, normally, the molding is performed in a state in which the fixed mold 1 and the movable mold 2 are horizontally arranged (that is, the mold is opened and closed in the horizontal direction). However, it is also possible to perform the molding in a state where they are lined up and down as shown.

The fixed mold 1 comprises a fixed mold plate 6 and a fixed mounting plate 7 fixed to the surface of the fixed mold plate 6 opposite to the movable mold 2. The fixed side mounting plate 7 is attached to a fixed side platen of an injection molding machine (not shown). 7a shown in FIG.
Is a through hole formed in the fixed side mounting plate 7 for passing a bolt for mounting on the fixed side platen. A sprue bush 8 to which the nozzle of the injection molding machine is connected is fixed by a bolt 9 to the central portion of the fixed-side mounting plate 7. The sprue bush 8 has a sprue 10 which is a material passage inside, but the fixed side mounting plate 7 and the fixed side mold plate 6 are penetrated, and the tip thereof is to the movable mold 2 side of the fixed side mold plate 6. It is protruding. Further, on the surface of the sprue bush 8 opposite to the movable die 2,
An annular locate ring 11 is arranged and a bolt 12
Is fixed to the sprue bush 8.

The fixed-side mold plate 6 is fixed to the fixed-side mounting plate 7 with bolts 16 and has a substantially disk-shaped cavity block 17 as a cavity forming member, and the fixed-side mounting plate 7 is fixed with bolts 18. And a substantially annular fixed side positioning ring 19 as a positioning member. The fixed-side positioning ring 19 includes the step portion 20 and the cavity block 1 formed on the peripheral portion of the surface of the fixed-side mounting plate 7 on the movable die 2 side.
7 is fitted on the outer peripheral side and is aligned with the cavity block 17 at the stage of mold production. And
The fixed side positioning ring 19 has a tapered surface 21 on the inner peripheral surface of the movable mold 2 side portion, the diameter of which increases toward the movable mold 2 side. The angle of the tapered surface 21 with respect to the mold opening / closing direction is about 5 to 30 °.

Further, as shown in FIG. 3, columnar guide pins 22 are fixed to the two corners of the fixed side mounting plate 7 which are located substantially on a diagonal line. As shown in FIG. 2, the guide pin 22 has a flange portion 23 formed on one end side thereof abutted against the fixed side mounting plate 7, and one end side of the flange portion 23 is formed on the fixed side mounting plate 7. Is fitted in the hole 24 and is fixed by the auxiliary member 25 provided on the other surface side of the fixed side mounting plate 7 and the bolt 26 penetrating the auxiliary member 25 and screwed to the end surface of the guide pin 22. ing. And
The guide pin 22 projects toward the movable mold 2 side with the mold opening / closing direction as the axial direction. Further, a flange-shaped stopper 27 is fixed to the tip end surface of the guide pin 22.

Further, a step portion 31 is formed on the outer peripheral portion on the movable die 2 side of the cavity block 17 shown in FIG. 1, and an annular outer peripheral stamper retainer 32 is fitted to the step portion 31. Are fixed by bolts 33. On the other hand, an inner peripheral stamper retainer 35 as a substantially cylindrical tubular member is fitted and fixed in the through hole 34 as a hole formed in the central portion of the cavity block 17. As shown in FIG. 4, a stamper 36 for forming irregularities on the optical disc is detachably mounted on the cavity block 17, and the outer peripheral stamper retainer 32 fixes the outer peripheral portion of the stamper 36. Then, the inner circumference stamper presser 35 is the stamper 3
The inner peripheral portion of 6 is fixed. That is, FIG.
As shown in FIG. 3, a claw portion 37 for pressing the inner peripheral portion of the stamper 36 is formed on the outer peripheral portion of the tip of the inner peripheral stamper retainer 35 on the side surface of the movable die 2. Further, the sprue bush 8 is fitted in a cylindrical inner peripheral stamper retainer 35. Then, the movable die 2 in the sprue bush 8
A concave portion 38 communicating with the sprue 10 is formed on the leading end surface on the side. The stamper 36 is made of a metal plate such as Ni. In the case of a DVD stamper, the stamper 36 has an arc shape formed along the disc circumferential direction such as a groove portion and a land portion that define the information recording area of the DVD. The mold for forming the convex portions and the circular arc-shaped groove formed between these convex portions is provided on one surface. In the case of a CD stamper, it has a mold for forming pits for recording information along the disc circumferential direction.

In the mold apparatus of the present embodiment, the provision of the claw portion 37 enables the stamper 36 to be more reliably pressed against the stamper support surface 17a and fixed. As a result, it is possible to prevent the stamper 36 from floating from the stamper support surface 17a during molding, and prevent damage to the stamper 36 and the stamper support surface 17a. That is, when the resin is filled while the stamper 36 is floating from the stamper supporting surface 17a, the stamper 36 is pressed against the stamper supporting surface 17a by the pressure of the resin that is filled with the high pressure, and the contact between them causes these Although the members may be worn, such contact can be prevented if the stamper 36 is fixed on the stamper supporting surface 17a.

Further, as shown in FIG. 1, in the peripheral edge of the surface of the cavity block 17 on the product cavity 3 side,
A groove is formed in a substantially annular shape, and the exhaust passage 4 is connected to the groove. Although only one exhaust passage 4 is shown in FIG. 1, it is provided at about 8 to 12 places along the groove. The exhaust passage 4 is connected to an exhaust means (not shown), and the stamper 36 is fixed by exhausting the inside of the exhaust passage 4 by the exhaust means. That is, the exhaust passage 4 constitutes a vacuum chuck mechanism for adsorbing and fixing the outer peripheral side of the stamper 36.

The movable die 2 includes a movable side mold plate 41, a movable side receiving plate 42 fixed to a surface of the movable side mold plate 41 opposite to the fixed mold 1, and a fixing on the movable side receiving plate 42. A movable side mounting plate 44 fixed by a bolt 43 is provided on the surface opposite to the mold 1. The movable side attachment plate 44 is attached to the movable side platen of the injection molding machine. The movable side mold plate 41 has a substantially disk-shaped core block 46 as a cavity forming member fixed to the movable side receiving plate 42 with a bolt 45, and a positioning member fixed to the movable side receiving plate 42 with a bolt 47. And a substantially annular movable side positioning ring 48. The movable side positioning ring 48 is fitted to the stepped portion 49 formed on the outer peripheral portion of the surface of the movable side receiving plate 42 facing the fixed die 1 and the outer peripheral side of the core block 46, and the die manufacturing is performed. At this stage, the core block 46 is centered. Further, the movable side positioning ring 48 has a tapered surface 50 to which the tapered surface 21 of the fixed side positioning ring 19 abuts when the mold is closed. Furthermore, this tapered surface 50
On the outer peripheral side of the movable side positioning ring 48, a spacer 51 against which the fixed side positioning ring 19 abuts is fixed by a bolt 52 to the surface of the movable side positioning ring 48 facing the fixed side positioning ring 19. That is, the fixed side positioning ring 19 and the movable side positioning ring 48 are fitted with a spigot.

Further, as shown in FIG. 2, two corner portions of the movable side receiving plate 42 and the movable side mounting plate 44 which are located substantially on a diagonal line and the through holes 24 of the fixed side receiving plate 7 are formed. A through hole 56 is formed at a position facing each other. Then, in the through holes 56 of the movable side receiving plate 42, guide pin receivers 58 into which the guide pins 22 on the fixed mold 1 side are slidably fitted in the mold opening / closing direction are incorporated. These guide pin receivers 58 have the through holes 56.
Cylindrical guide bush 59 fitted and fixed inside
And a retainer 60 composed of a slide ball bearing, a slide roller bearing, or the like slidably mounted on the inner peripheral side of the guide bush 59. The guide pin 2 is provided on the inner peripheral side of the retainer 60.
2 is always fitted. The stopper 27 of the guide pin 22 prevents the retainer 60 from coming off. In addition, the through hole 5 formed in the movable side mounting plate 44
The distal end of the guide pin 22 is inserted into the guide 7.

Further, a step portion 66 is formed on the outer peripheral portion of the fixed block 1 side of the core block 46 shown in FIG. 1. The step portion 66 is provided with an annular abutment ring 67. It is fitted so that it can slide in the mold opening and closing direction.
Incidentally, 68 is a bolt for preventing the butting ring 67 from coming off. Also, the butting ring 67 and the core block 46
A slide bearing 69 is interposed between the slide bearing 69 and the outer peripheral surface. Further, the butting ring 67 is provided with the spring 70.
Is urged toward the fixed mold 1 side. The abutment ring 67 abuts the outer peripheral stamper retainer 32 and the stamper 36 on the fixed mold 1 side when the mold is closed, and forms the outer peripheral surface of the optical disc.

Further, a substantially annular work outlet 77 is fitted in a recess 76 formed in the surface of the core block 46 on the side of the fixed mold 1 at the center thereof, and the rear end of the recess 76 is inserted into the recess 76. It is fixed by the inserted bolt 78. An air passage 79 formed in the core block 46 and the movable-side receiving plate 42 communicates with the gap between the processing blow-out insert 77 and the inner peripheral surface of the recess 76.

Further, a substantially cylindrical projecting sleeve 81 is fitted in the work blowing-out insert 77 so as to be slidable within a predetermined range in the mold opening / closing direction. The protruding sleeve 81 penetrates the core block 46 and has one end side located inside the movable side receiving plate 42.
A slide bearing 82 is interposed between the two. Further, the protruding sleeve 81 is provided with a spring 83.
Is urged to the side opposite to the fixed mold 1. Note that 84
Is a regulation plate fixed in the movable side receiving plate 42 for regulating the sliding range of the protruding sleeve 81.

Further, a gate cut sleeve 86 as a substantially cylindrical gate cut member is fitted in the protruding sleeve 81 so as to be slidable within a predetermined range in the mold opening / closing direction. The gate cut sleeve 86 penetrates the protruding sleeve 81 and the regulation plate 84,
A slide bearing 87 is interposed between the gate cut sleeve 86 and the protruding sleeve 81. A flange portion 88 formed at one end of the gate cut sleeve 86 is located closer to the movable side attachment plate 44 than the regulation plate 84. Further, the gate cut sleep 86 is biased by the spring 89 toward the side opposite to the fixed mold 1.

Further, the movable side mounting plate 44 is provided with
A protruding plate 91 is supported so as to be slidable in a predetermined range in the mold opening / closing direction. The protruding plate 91 is used for the spring 9
It is urged by 2 to the side opposite to the fixed die 1. And
A protrusion pin 93 fixed to the protrusion plate 91 is slidably fitted in the gate cut sleeve 86. Further, the interlocking pin 94 fixed to the protruding plate 91 penetrates the flange portion 88 of the gate cut sleeve 86 and the regulating plate 84 and abuts against the protruding sleeve 81. Further, a receiving portion 95 provided on the flange portion 88 of the gate cut sleeve 86 is slidably passed through the protruding plate 91.

Then, as shown in FIG. 4, the fixed mold 1
A gate 96 for connecting the sprue 10 on the fixed die 1 side to the product cavity 3 is formed between the outer peripheral portion of the tip surface of the sprue bush 8 on the side and the outer peripheral portion of the gate surface of the gate cut sleeve 86 on the movable die 2 side. It is like this. In addition, the gate cut sleeve 86 is provided in the recess 3 of the sprue bush 8.
By fitting into the gate 8, the resin as the molding material in the sprue 10 and the resin in the product cavity 3, that is, the optical disk are cut at the gate 96, and an opening hole at the center of the optical disk is formed. There is. Therefore, in the fixed mold 1, in addition to the cavity block 17, a part of the optical disk is formed by the inner peripheral stamper retainer 35 and the outer peripheral portion of the tip end surface of the sprue bush 8. In addition, in the movable die 2, in addition to the core block 46, the work blow-out insert 77 and the protruding sleeve 8 are provided.
1 also forms part of the optical disc.

Further, in the mold apparatus of this embodiment, the stamper 3 of the cavity block 17 shown in FIG.
A cBN film 17b is formed on the surface 17a that supports the CBN 6. By forming the cBN film 17b, it is possible to prevent wear of the stamper supporting surface 17a and the stamper 36.

The stamper 36 is a molding material 350.
When the molten resin heated to about 390 ° C. is introduced into the product cavity 3, the temperature rises to about 350 to 390 ° C. When the resin is cooled and solidified after the filling, the temperature is lowered to about 100 ° C. Since such heating and cooling is repeated for each shot, the stamper 36
Will repeat expansion and contraction. Further, the stamper 36 receives stress due to the molten resin filled at high temperature and high pressure. That is, the stamper 36 is repeatedly slid along the cavity supporting surface 17a of the cavity block 17a. Conventionally, the stamper 36 slides to wear the stamper support surface 17a and the back side of the stamper 36, and the abrasion powder generated therewith causes the back side (cavity block 17 side) and the top side (product cavity 3) of the stamper 36. However, according to the present invention, the stamper supporting surface 17a, which is a sliding surface, is hard, has excellent wear resistance and corrosion resistance, is smooth, and has a low friction coefficient. By forming the cBN film 17b, the stamper 36 can be smoothly slid, and the generation of abrasion powder can be effectively suppressed. In particular, the outer peripheral portion of the stamper supporting surface 17a is apt to wear due to the large expansion and contraction width of the stamper 36. However, the outer peripheral portion of the stamper supporting surface 17a is also effectively prevented by the formation of the cBN film 17b. be able to.

The film thickness of the cBN film 17b is 0.2 μm.
It is preferably in the range of ˜4 μm. Film thickness 0.2
If it is less than μm, abrasion resistance and strength of the film itself become insufficient, and if it exceeds 4 μm, internal stress of the film becomes strong.
Peeling is likely to occur.

Further, since the resin filled in the product cavity 3 is in a molten state at a high temperature (350 to 390 ° C.), the gas component of the organic compound vaporized by this resin is entrained in the resin and the product cavity 3 Will be introduced in. This organic compound-based gas component also enters between the stamper 36 and the stamper supporting surface 17a and is cooled by the cavity block 17, so that a part thereof becomes a resin powder after hundreds of thousands of molding cycles. A small amount adheres to the stamper support surface 17a and the back surface side of the stamper 36.
Further, in order to increase production efficiency using a polycarbonate resin for DVD, when the resin is injected at a high temperature and a high pressure, in recent years, a resin heated to a temperature as high as 350 to 390 ° C., which is higher than ordinary resin molding, is filled. Since the resin powder has become remarkable, the generation of the resin powder has become remarkable, and it becomes a problem especially when the molding cycle of hundreds of thousands of times is repeated. Particularly, in the peripheral portion of the exhaust passage 4 provided in the cavity block 17, the negative pressure is higher than in other portions, so that the resin powder is likely to accumulate. The resin powder thus attached to the stamper supporting surface 17a reduces the flatness of the stamper 36 and causes a transfer failure. Therefore, the stamper 3 after the molding cycle is pressed.
6 Need to be removed at the time of replacement. In the mold apparatus of this embodiment, since the cBN film 17b is formed on the stamper supporting surface 17a, it is originally difficult for resin powder to adhere to the mold, and even if resin powder adheres, its adhesive force Can be weakened. Therefore, in the mold device according to the present invention,
The resin powder generated on the stamper supporting surface 17a can be easily removed by replacing the stamper 36 with a cloth such as a waste cloth.

Further, the gas component vaporized by the resin is
In many cases, it is corrosive, and in the conventional mold device, the phenomenon that the stamper support surface is corroded and discolored by this gas component has been a problem, but in the mold device of the present embodiment, the stamper support surface 17a is Due to the formed cBN film 17b, the gas component has a stamper supporting surface 1 of the cavity block 17.
It is possible to prevent it from reaching 7a. As a result, a long-life mold device in which corrosion of the cavity block 17 is unlikely to occur is realized. Therefore,
According to the mold apparatus of the present embodiment, it is possible to provide the stamper supporting surface 17a which is not worn even when the cycle molding process is performed hundreds of thousands of times, and in which resin powder and abrasion powder are hard to adhere. .

Next, a method of molding an optical disk using the mold apparatus having the above-mentioned structure will be described. 1, FIG. 2, and FIG. 4, the fixed mold 1 and the movable mold 2 are drawn side by side in the drawing, but normally, the molding is performed in a state where the fixed mold 1 and the movable mold 2 are horizontally arranged. However, it is also possible to perform the molding in a state where they are lined up and down as shown. Both the guide pins 22 of the fixed die 1 shown in FIGS. 2 and 3 are always fitted to the guide pin receivers 58 of the movable die 2 regardless of whether the fixed die 1 and the movable die 2 are opened or closed. Is. As a result, the fixed die 1 and the movable die 2 are aligned with each other. That is, the central axis of the cavity block 17 of the fixed mold 1 and the central axis of the core block 46 of the movable mold 2 are located on the same straight line.

At the time of molding an optical disk, first, the fixed mold 1 and the movable mold 2 are closed, and the fixed mold 1 and the movable mold 2 are closed.
A product cavity 3 is formed in between. In this state of the mold closed, the abutment ring 67 of the movable mold 2 abuts on the stamper 36 of the fixed mold 1, and the positioning rings 19 and 48 of the fixed mold 1 and the movable mold 2 are interlocked with each other. The tapered surfaces 21 and 50 are fitted into each other by taper. Then, a molten thermoplastic resin as a molding material is injected from the nozzle of the injection molding machine into the sprue 10. This resin flows into the product cavity 3 from the sprue 10 through the gate 96 (filling step). Initially, the mold clamping force of the fixed mold 1 and the movable mold 2 is relatively weak, and the pressure of the resin filled in the product cavity 3 causes the fixed mold 1 and the movable mold 2 to slightly move, for example, 0.1 to 10.
Although it opens about 0.3 mm and the tapered surfaces 21 and 50 of the positioning rings 19 and 48 are slightly separated, the abutment ring 67 slidably supported by the core block 46 of the movable die 2 is biased by the spring 70. Is held in abutment with the stamper 36.

After the resin is filled in the product cavity 3 in this way, the receiving portion 95 of the gate cut sleeve 86 is pushed toward the fixed mold 1 by a pressing rod (not shown) provided on the injection molding machine side. As a result, the gate cut sleeve 86 moves to the fixed mold 1 side and fits into the recess 38 of the sprue bush 8 of the fixed mold 1. As a result, the sprue 10 and the product cavity 3 are blocked at the gate 96, and an opening hole at the center of the optical disc is formed (gate cutting step). Further, as the die clamping of the fixed die 1 and the movable die 2 is strengthened, almost the entire movable die 2 including the core block 46 moves to the fixed die 1 side. As a result, the resin in the product cavity 3 is compressed (compression step). When this compression step is completed, the tapered surfaces 21 and 50 of the positioning rings 19 and 48 of the fixed die 1 and the movable die 2 are again taper-fitted to each other. This ensures that the stationary die 1 and the movable die 2 are aligned with each other after the end of the compression process.

Further, after the resin in the product cavity 3, that is, the optical disk is cooled and solidified, the fixed mold 1 and the movable mold 2 are opened. With this mold opening, the molded optical disk and the resin solidified in the sprue 10 first separate from the fixed mold 1. Then, the ejecting plate 91 is pushed toward the fixed mold 1 by a pressing rod (not shown) provided on the injection molding machine side, and the ejecting pin 93 moves to the fixed mold 1 side in conjunction with the ejecting plate 91. , The resin solidified in the sprue 10 is ejected and released from the movable mold 2. In addition, the interlocking pin 9 fixed to the protruding plate 91
By being pushed by 4, the ejection sleeve 81 moves to the fixed die 1 side, and the inner peripheral portion of the optical disc is ejected and released from the movable die 2. At the time of this mold release, the air supplied from the air passage 79 is blown out from the gap between the air blowing insert 77 and the core block 46, so that the vacuum break between the optical disk and the movable mold 2 is performed. Then, the released optical disc is taken out by a take-out robot (not shown). At that time, the take-out robot moves the guide pin 2 between the fixed die 1 and the movable die 2.
2 and the corners where the guide pin receivers 58 are not provided come in and go out. It is to be noted that what is molded in this way is not the final product, which is the optical disc, but the substrate thereof, after which a protective layer, recording layer, reflective layer, overcoat layer, etc. are appropriately formed. To be done.

According to the configuration of the present embodiment, the guide pin 22 provided on the fixed die 1 is fitted into the guide pin receiver 58 provided on the movable die 2 so as to be slidable in the die opening / closing direction. Since the movable die 2 and the movable die 2 are aligned with each other, even when the fixed die 1 and the movable die 2 are opened and the tapered surfaces 21 and 50 of the positioning rings 19 and 48 are separated from each other, the movable die and the movable die 2 are movable. Can be aligned with the mold 2. That is, in the filling process, gate cutting process and compression process after the fixed mold 1 and the movable mold 2 are closed once, the fixed mold 1 and the movable mold 2 are slightly opened. It is possible to hold the fixed die 1 and the movable die 2 in a state of being aligned with each other to some degree of accuracy against the gravity applied to the die 2. Therefore, when the gate cut sleeve 86 on the movable die 2 side is fitted into the recess 38 of the fixed die 1 in the gate cutting step,
The gate cut sleeve 86 is securely and accurately fitted in the recess 38. Therefore, the opening hole of the optical disk can be accurately formed at a predetermined position, and the occurrence of defects such as burrs in the opening hole can be prevented.

After the end of the compression process, the fixed mold 1
And the movable mold 2 are finally completely closed to form the product cavity 3
In the final product shape, the tapered surfaces 2 of the positioning rings 19 and 48 of the fixed mold 1 and the movable mold 2 are
The fixed die 1 and the movable die 2 are aligned with each other by taper-fitting the first die 1 and the second die 50. At this time, since the positioning rings 19 and 48 are not movably supported by the fixed mold 1 and the movable mold 2 but are fixed, the alignment by the positioning rings 19 and 48 is performed by the guide. Pin 22 and guide pin receiver 58
It is more reliable and accurate than centering by using only. As described above, since the cores can be surely aligned when the molds are closed, the product cavity 3 can be accurately defined, and the pressure of the resin introduced from the sprue 10 is more uniform in the product cavity 3. Can be Therefore,
The pressure of the resin acting on the stamper 36 is made more uniform, and the stamper 36 and the stamper supporting surface 17a (cBN
Sliding with the membrane 17b) can be made smoother and wear of these members can be suppressed. Therefore, according to the mold apparatus of this embodiment, the life of the stamper 36 can be extended in combination with the action of the cBN film.

Further, in this embodiment, the guide pin 2
2 and the guide pin receiver 58 are provided only in two sets,
The final centering of the fixed mold 1 and the movable mold 2 is performed by the positioning rings 19 and 48, and the guide pin 22 and the guide pin receiver 58 are auxiliary, so that the fixed mold 1 is fixed.
And it is sufficient to have two corners of the movable mold 2. When the fixed mold 1 and the movable mold 2 are opened to take out the molded optical disk, a take-out robot is operated between the fixed mold 1 and the movable mold 2 via the corners without the guide pins 22 and the guide pin receivers 58. By taking in and out, the guide pin 22 and the guide pin receiver 58 do not interfere with the taking out of the optical disc.

The present invention is not limited to the above embodiment, and various modifications can be made. For example, in the above-described embodiment, the fixed mold 1 is provided with the guide pin 22 so as to project, and the guide pin 22 into which the guide bin 22 is slidably fitted is provided in the movable mold 2. The guide pin may be provided on the fixed type and the guide pin receiver may be provided on the fixed type. Further, in the above-described embodiment, the guide pin 22 and the guide pin receiver 58 are two sets, but one set or three sets.
It may be more than one set.

According to the optical disk molding die apparatus of the present invention, the height of the inner surface of the information recording portion is 0.04 mm or more (preferably 0.05 mm or more) higher than the surface of the information recording portion. ) It is also possible to manufacture an optical disk having a protruding annular convex portion. An example of an optical disc having such a configuration is shown in FIG. FIG. 5 is a diagram showing a partial cross-sectional structure of the optical disc. The optical disc 101 shown in FIG. 5 has a disc shape, has an opening 102 in the center thereof, and has a portion other than the inner peripheral portion and the outer peripheral portion as an information recording portion 103. In addition, one surface of the optical disc 101 is located on the inner peripheral side of the information recording unit 103 and has a height h higher than the surface of the information recording unit 103.
An annular convex portion 104 protruding by 0.04 mm or more is formed concentrically with the entire optical disc 101. The height h of the convex portion 104 is more preferably 0.05 mm or more. In the optical disc 101 having such a structure, even if the burr 105 is generated on the surface of the optical disc 101 during molding,
For example, when the optical disc 101 is mounted on the turntable 106 of the optical disc drive apparatus, the convex portion 104 is placed on the turntable 106 instead of the burr 105. Therefore, the optical disc 101 can be mounted on the turntable 106 without being tilted without being affected by the burr 105, and surface wobbling during rotation of the optical disc can be prevented. Alternatively, the hub can be mounted parallel to the optical disc when the hub is later attached to the optical disc.

Next, the optical disc 101 having the above-mentioned convex portion
The configuration of the mold apparatus for manufacturing the above will be described below with reference to FIG. FIG. 6 is a diagram showing a partial cross-sectional structure of the optical disk molding die apparatus according to the present invention, showing a central portion of a product cavity for molding an optical disk. The basic structure of the mold device shown in FIG. 5 is almost the same as that of the mold device shown in FIG. 1, and the same components as those in FIG. 1 are designated by the same reference numerals. A characteristic point of the mold device shown in FIG. 6 is that the depth of 0.04 mm or more (preferably 0.05 m) is formed on the surface of the air blow-out insert 77 on the product cavity 3 side.
This is the point where an annular recess 99 of (m or more) is engraved.
By performing molding using the mold device having such a configuration,
As shown in FIG. 6, it is possible to manufacture the optical disc 101 having the convex portion 104 formed by transferring the shape of the concave portion 99.

[0043]

EXAMPLES Example 1 A cBN film was vapor-deposited on a stamper supporting surface of a mold device by a plasma jet CVD method.
A stainless steel disk (180 mmφ × 20 mm thick) whose plane to be the stamper holding surface is mirror-polished is placed in the reaction vessel to serve as a substrate, and a DC plasma torch is provided above it to evacuate Ar, N ₂ , BF ₃ , H ₂ mixed gas was caused to flow from the torch, decomposed in plasma, and vapor-deposited on the substrate. The pressure during film formation is 50 Torr (50 × 133 Pa)
The substrate was cooled with water and maintained at 1000 ° C. In addition, the substrate is rotated during film formation to uniformly c
The BN film was coated. Reaction time 30
In 1 minute, a vapor deposition film of 1 μm was obtained. As a result of analyzing the formed thin film by X-ray diffraction, it was confirmed to be a cBN film.

(Example 2) A cBN film was vapor-deposited on the stamper supporting surface of a mold by a magnetron sputtering method. A pedestal for magnetron sputtering is placed in a vacuum vessel, a hexagonal BN target is fixed to this pedestal, and a stainless steel disk (180 mmφ × 20 mm thick with a flat surface serving as a stamper supporting surface mirror-polished on the opposite surface) ) Is used as a substrate, the pressure is reduced to a vacuum, and then Ar is introduced to obtain 2 × 10 ⁻⁴ T
orr (266 × 10 ⁻⁴ Pa), 13.56 Mz
Was applied to the target to perform sputtering. At that time, a high frequency (bias voltage) was also applied to the substrate side.
A film having a thickness of 1 μm was obtained by forming the film for 1 hour. As a result of X-ray diffraction analysis of the formed thin film, it was found to be an amorphous BN film.

(Comparative Examples 1 and 2) Next, as Comparative Examples 1 and 2, 2 μm of TiN was used on the surface to be the stamper supporting surface, respectively.
The formed stainless steel substrate and DLC (Diamond Like
A stainless steel substrate was formed by depositing 1 μm of carbon.

The substrates of Examples 1 and 2 and Comparative Examples 1 and 2 obtained above were mounted in a mold apparatus so that the film-forming surface would be the stamper holding surface, and injection molding was carried out. (number of shots)
The results of visual observation of the state of the stamper holding surface after that are shown in Table 1.

[0047]

[Table 1]

As shown in Table 1, the stamper supporting surface is c
The mold having the BN film formed and having the film thickness in the range of 0.2 μm to 4 μm, which satisfies the requirements of the present invention, has scratches, peeling of the cBN film, discoloration, and adhesion on the stamper supporting surface even after 300,000 shots. No kimono or the like was observed, and it was confirmed that it had extremely good durability.

[0049]

As described above in detail, in the optical disk molding die device of the present invention, the stamper supporting surface is coated with the hard cBN film, so that the stamper is heated and cooled during injection molding. It is possible to effectively prevent the stamper supporting surface and the stamper from being worn due to expansion and contraction of the stamper, and it is possible to extend the life of the stamper.
Further, it is possible to prevent the stamper supporting surface from being corroded due to a gas component introduced into the product cavity by being entrained in the molten resin, so that the life of the mold device can be extended.

[Brief description of drawings]

FIG. 1 is a cross-sectional configuration diagram of an optical disk molding die device according to the present invention.

FIG. 2 is a cross-sectional view of a guide pin and a guide pin receiver provided in the optical disk molding die apparatus according to the present invention.

FIG. 3 is a plan view of a fixed mold of the mold device shown in FIG.

FIG. 4 is an enlarged cross-sectional view near the gate of the mold device shown in FIG.

FIG. 5 is a partial cross-sectional view showing an example of an optical disc manufactured by the mold device according to the present invention.

6 is a cross-sectional configuration diagram showing a configuration of a mold apparatus for manufacturing the optical disc shown in FIG.

FIG. 7 is a partial cross-sectional view showing an example of an optical disk molding die.

[Explanation of symbols]

1 Fixed type (first type body) 2 movable type (second type body) 3 product cavity 10 sprues 17a Stamper support surface 17b cBN film 19 Fixed side positioning ring 21 Tapered surface 22 Guide pin (guide member) 38 recess 48 Movable side positioning ring (positioning member) 50 taper surface 58 Guide pin receiver (guide member) 86 Gate cut sleeve (gate cut member)

Claims (6)

[Claims] 1. A first mold body and a second mold body that define a cavity space for molding an optical disk by injection molding, the optical disk being formed on the first mold body or the second mold body. A stamper supporting surface for receiving a stamper for forming the unevenness is formed, and a stamper supporting surface of the first mold body or the second mold body,
A mold device for optical disk molding, which is coated with a cBN film. 2. The film thickness of the cBN film is from 0.2 μm to 4
The mold apparatus for optical disk molding according to claim 1, wherein the mold apparatus has a range of μm. 3. The cBN film is formed by a CVD method or a sputtering method.
Alternatively, the mold device for optical disk molding according to item 2. 4. A mold having the stamper supporting surface,
4. The optical disk molding die apparatus according to claim 1, further comprising a vacuum chuck mechanism that exhausts the back surface side of the stamper to fix the stamper. 5. A mold body having the stamper supporting surface,
5. The optical disk molding die apparatus according to claim 1, further comprising a claw portion for fixing an inner end portion of the stamper. 6. A positioning member, which is provided on opposite surfaces of the first mold body and the second mold body and has a tapered surface for taper fitting when the mold is closed, and the first mold body and the first mold body. Guide pin provided on one of the two mold bodies and at a position facing the guide pin of the other mold body, and the guide pin is slidably fitted in the opening / closing direction of the mold body. 6. A mold device for optical disk molding according to claim 1, further comprising: a guide member having a receiver.