JP2003225926A - Mold device for molding optical disk - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a mold device for molding an optical disk having good heat resistance and durability by preventing the abrasion of mold bodies caused by a heat history received in each shot and preventing mechanical abrasion when a solidified resin is taken out. <P>SOLUTION: A fixed mold (first mold body) 1 and a movable mold (second mold body) 2 for partitioning a cavity space 3 for molding the optical disk by injection molding are provided. A stamper supporting surface 17a for receiving a stamper for forming unevenness on the optical disk is formed in the first mold body 1 or the second mold body 2, and the resin contact surface 2a of at least one of the fixed mold 1 and the movable mold 2 is coated with a TiN film 2b. <P>COPYRIGHT: (C)2003,JPO

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 apparatus 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, the temperature of the resin injected from the sprue 204 is about 350 ° C. to 390 ° C., so that the movable portion 201 and the fixed portion 202 are 350 ° C. to 390 ° C. at the time of resin filling.
Heated to about ℃, then 1 to solidify the resin
It is cooled down to about 00 ° C. Stamper support surface 201
The resin contact surface of the fixed die 202 facing A is not only subjected to such a heat history for each shot, but is also repeatedly subjected to mechanical friction when the solidified resin is opened and taken out. Fine scratches will occur. Further, the resin held at a high temperature of about 350 ° C. to 390 ° C. often accompanies a corrosive gas component, and thus the fixed mold facing the resin contact portion of the cavity space C, particularly the stamper supporting surface 201A. Resin contact surface 202 of 202
A is susceptible to corrosion and its surface is roughened. The surface roughness and fine scratches on the resin contact surface 202A are
Since it is transferred to the disk as it is, problems such as a decrease in product yield due to transfer failure and a shortened life of the mold have occurred.

The present invention has been made in order to solve the above-mentioned problems, and prevents the mold body from being damaged due to the heat history received at each shot, and prevents mechanical wear when the solidified resin is taken out. It is an object of the present invention to provide a mold device for optical disk molding that is prevented and has excellent heat resistance and durability.

[0005]

In order to solve the above-mentioned problems, the present invention provides a first mold body and a second mold body which define a cavity space for injection molding a resin to mold an optical disk.
And a stamper supporting surface for receiving a stamper for forming irregularities on the optical disk is formed on the first mold body or the second mold body, and the first mold body and the second mold body are formed. Provided is a mold device for optical disk molding, wherein at least one resin contact surface of the body is covered with a TiN film. The mold apparatus according to the present invention having the above-mentioned configuration is the first
On the resin contact surface of at least one of the mold body and the second mold body,
By forming a TiN film, which is a hard thin film with high adhesive strength, it is possible to prevent wear of the mold body due to expansion and contraction due to heating and cooling for each shot, and take out the resin (molded optical disk) solidified by opening the mold. Mechanical wear at the time can be prevented. Further, since the TiN film is not corroded by the corrosive gas component accompanying the molten resin, the above T
The surface of the resin contact surface covered with the iN film is not roughened. Therefore, according to the mold device according to the present invention, it is possible to suppress the occurrence of surface roughness and fine scratches on the resin contact surface of the mold body, it is possible to reduce transfer defects due to surface roughness and fine scratches on the resin contact surface, The mold can have a long life.

In the optical disk molding die apparatus according to the present invention, the thickness of the TiN film is 0.5 μm to 5 μm.
The range is preferably The thickness of the TiN film is 0.
If it is less than 5 μm, the durability of the film is insufficient because it is too thin,
When the mold is opened and the solidified resin is taken out, abrasion is likely to occur, and moreover, it is susceptible to corrosion due to corrosive gas components. Further, if the film thickness exceeds 5 μm, peeling of the film is likely to occur due to the stress inherent in the TiN film, and the surface condition becomes rough, which is not preferable.

Further, in the optical disk molding die device, it is preferable that the TiN film is formed by a sputtering method. Further, in the optical disk molding die device, it is preferable that the TiN film is formed by a chemical vapor deposition method.

Next, in the optical disk molding die apparatus according to the present invention, the mold body 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 the 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.
Furthermore, by fixing with the above-mentioned claw portion, 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, even by this action, the life of the stamper can be extended, and the TiN
The life of the stamper can be further extended in combination with the action of the film.

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,
A guide member provided at a position facing the guide pin of the other mold body and having a guide pin receiver into which the guide pin is slidably fitted in the opening / closing direction of the mold body. You can also

At the time of molding an optical disk, a pair of mold bodies are closed, and a molding material is filled in a product cavity formed between the mold bodies. 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 TiN film, the life of the stamper can be further extended.

[0012]

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 side 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 as a material passage inside, but penetrates through the fixed-side mounting plate 7 and the fixed-side mold plate 6, and its tip projects toward the movable mold 2 side of the fixed-side mold plate 6. ing. Further, an annular locate ring 11 is arranged on the surface of the sprue bush 8 opposite to the movable die 2, and is fixed to the sprue bush 8 by a bolt 12.

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 has a step portion 20 formed on the peripheral portion of the surface of the fixed-side mounting plate 7 on the movable die 2 side and the cavity block 1.
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, cylindrical 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 of the cavity block 17 shown in FIG. 1 on the movable die 2 side, 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 disk is detachably mounted on the stamper supporting surface 17a of the cavity block 17, and the outer peripheral stamper retainer 3
2 fixes the outer peripheral portion of the stamper 36, and the inner peripheral stamper retainer 35 fixes the inner peripheral portion of the stamper 36. That is, as shown in FIG. 4, a claw portion 37 for pressing the inner peripheral portion of the stamper 36 is formed on the outer peripheral portion of the tip end of the movable die 2 side surface of the inner peripheral stamper retainer 35. The sprue bush 8 is fitted in the cylindrical inner peripheral stamper retainer 35. The sprue bushing 8 has a sprue 10 on the end surface on the movable die 2 side.
A recess 38 communicating with is formed. 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 fixed to the stamper support surface 17a. 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 filled at a high pressure.
At that time, there is a possibility that these members may be worn due to the contact between the two.
If it is fixed on the top, such contact can be prevented.

Further, as shown in FIG. 1, in the peripheral portion 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 has 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 includes 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 is manufactured. At this stage, the core block 46 is centered. The movable side positioning ring 48 has a taper surface 50 which the taper 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, through-holes (holes) of the fixed-side receiving plate 7 at the two corners of the movable-side receiving plate 42 and the movable-side mounting plate 44 which are located substantially on a diagonal line. ) 24, a through hole 56 is formed at a position facing the hole 24. 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 are cylindrical guide bushes 59 fitted and fixed in the through holes 56, and slide ball bearings or slide rollers slidably mounted on the inner peripheral side of the guide bushes 59. The retainer 60 includes a bearing and the like, and the guide pin 22 is always fitted to the inner peripheral side of the retainer 60.

The stopper 2 for the guide pin 22
Reference numeral 7 prevents the retainer 60 from coming off. Also,
The tip of the guide pin 22 is inserted into the through hole 57 formed in the movable side mounting plate 44.

Further, a substantially annular work outlet 77 is fitted in a recess 76 formed on the surface of the core block 46 on the side of the fixed mold 1 in the central portion 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 blow-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 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.

A gate cut sleeve 86, which is 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 on one end of the gate cut sleeve 86 is located closer to the movable side mounting 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 includes:
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 protrusion plate 91 penetrates the flange portion 88 of the gate cut sleeve 86 and the regulation plate 84 and abuts against the protrusion sleeve 81. Further, a receiving portion 95 projecting from the flange portion 88 of the gate cut sleeve 86 slidably penetrates the projecting 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 TiN film 2b is formed on the resin contact surface 2a of the movable mold 2 facing the stamper 36 shown in FIG. This T
The iN film 2b includes the core block 46 and the air blowing insert 7.
7, protruding sleeve 81, gate cut sleeve 86
Is formed on each of the resin contact surfaces 2a. This Ti
Since the N film 2b is formed, it is possible to prevent the resin contact surface 2a of the movable die 2 from being damaged by heat history. T
The iN film 2b is formed by sputtering, chemical vapor deposition (CVD).
Method) and the like.

The movable mold 2 is a molding material 350-39.
When the molten resin heated to about 0 ° C. is introduced into the product cavity 3, its temperature rises to about 350 to 390 ° C. When the resin is cooled and solidified after filling, 1
The temperature drops to about 00 ° C. Since such heating and cooling is repeated for each shot, the movable mold 2 repeats expansion and contraction. Further, the resin contact surface 2a of the movable die 2 receives stress due to the molten resin filled at high temperature and high pressure. Conventionally, a minute scratch is generated on the surface of the resin contact surface 2a due to the heat history received for each shot, and this is transferred to the disk, which is a cause of transfer failure. According to the present embodiment, the resin contact surface 2a of the movable die 2 facing the stamper 36 is formed with the TiN film 2b which is hard, has high heat resistance and wear resistance, and is smooth and has a low friction coefficient. The molten resin is filled more smoothly, and the resin contact surface 2 is expanded and contracted by heating and cooling for each shot.
It is possible to prevent the wear of a and to prevent mechanical wear of the resin contact surface 2a when the resin is opened and the solidified resin is taken out, whereby the durability of the resin contact surface 2a, in other words, the durability of the mold body and The maintenance cycle is greatly improved. In addition, since the TiN film 2b having a smooth and low friction coefficient is formed on the resin contact surface 2a, the molten resin is uniformly and quickly filled and flowed toward the peripheral portion of the product cavity 3 with the sprue 10 as the center. It can be done. Since the polymer chains of the molten resin have the property of being oriented in the flow direction, birefringence of the resin due to this orientation can be suppressed to a low level, and a high quality optical disc can be obtained. This is particularly remarkable when a polycarbonate resin having a large photoelastic coefficient, which is preferably used as a substrate material for DVD, is used. Further, since the TiN film 2b is hard, has high wear resistance, and has a low coefficient of friction, it is possible to suppress the warp of the substrate (optical disk substrate) due to the stress at the time of releasing the mold. It is possible to manufacture quality substrates (optical disc substrates).

The thickness of the TiN film 2b is 0.5 μm or more.
The range is preferably 5 μm. Film thickness is 0.5μ
If it is less than m, the durability of the film is insufficient because it is too thin,
When the mold is opened and the solidified resin is taken out, abrasion is likely to occur, and moreover, it is susceptible to corrosion due to corrosive gas components. On the other hand, if the film thickness exceeds 5 μm, peeling of the film is likely to occur due to the stress inherent in the TiN film, and the surface condition becomes rough, which is not preferable because the rough surface is transferred to the disk. A TiN film is formed on the resin contact surface 2a.
More than one layer may be laminated.

Further, since the resin filled in the product cavity 3 is in a molten state at a high temperature (350 to 390 ° C.), the vaporized organic compound gas component is entrained in the resin and the product cavity 3 Will be introduced in. A part of this organic compound-based gas component becomes resin powder after hundreds of thousands of molding cycles, and a small amount adheres to the resin contact surfaces of the fixed mold 1 and the movable mold 2 that define the product cavity 3. Further, in order to increase the production efficiency by using the polycarbonate resin for DVD, in the case of injecting the resin at high temperature and high pressure, in recent years, the temperature is higher than that of ordinary resin molding, which is 350
Since the resin heated to a temperature of up to 390 [deg.] C. is filled and molded, the generation of the above resin powder has become remarkable, and the molding cycle of hundreds of thousands of times is repeated. It's become a particularly problematic case. Since the resin powder attached to the product cavity 3 causes transfer failure, it needs to be removed when the stamper 36 is replaced after the molding cycle. In the mold device of the present embodiment, since the TiN film 2b is formed on the resin contact surface 2a, the resin powder does not easily adhere to the mold, and even if the resin powder adheres, the adhesive force is weakened. be able to. Therefore, in the mold apparatus according to the present invention, the resin powder generated in the product cavity 3 can be easily removed by wiping with a cloth such as a waste cloth when the stamper 36 is replaced.

Further, the above-mentioned gas components are those obtained by vaporizing or decomposing a part of the resin, and are generated from various additives for adjusting the resin characteristics, and are often corrosive. In the conventional mold device, a phenomenon in which the resin contact surface is corroded and discolored by this gas component has been a problem, but in the mold device of the present embodiment, the highly corrosive T
By providing the iN film 2b on the resin contact surface 2a, corrosion of the resin contact surface 2a is less likely to occur, and a die device having a long life is realized. Further, T covering the resin contact surface 2a
Since the iN film 2b is not corroded by corrosive gas components,
It is possible to prevent the surface of the resin contact surface 2a from being roughened by this corrosive gas component, and prevent a transfer failure due to the surface roughness of the resin contact surface. Further, it is possible to suppress the occurrence of birefringence caused by the non-uniformity of the flow at the time of filling the resin, which is caused by the surface roughness due to the corrosion of the resin contact surface 2a. Therefore, a mold with a long life capable of manufacturing a high quality optical disc. The device can be realized.

Next, a method of molding an optical disk using the mold apparatus having the above 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.
Open about 0.3 mm, and the tapered surfaces 21, 50 of the positioning rings 19, 48 are also slightly separated.

After the product cavity 3 has been filled with the resin 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.

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. Been done, D
Optical discs such as VD and CD are completed.

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,
Not only can the mold body be prevented from being worn and the life of the mold device can be extended, but also the occurrence of resin birefringence can be suppressed, and a high-quality optical disc can be manufactured.

Further, in the present 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 embodiment, the TiN film 2b includes the core block 46, the air blowing insert 77, the protruding sleeve 81,
Although the TiN film 2b is formed on the resin contact surface 2a of the gate cut sleeve 86, the TiN film 2b may be provided on the resin contact surface other than the stamper supporting surface 36 of the fixed die 1 and the movable die 2 or the inner surface of the resin gas escape gap. To give a specific example,
It may be provided on the surface of the sprue 10 of the fixed mold 1, the surface of the recess 38, the surface of the protruding pin 93 of the movable mold 2 on the side of the cavity 3 or the side surface thereof. The TiN film 2b may also be provided on the stamper supporting surface 36. Further, in the above-described embodiment, the guide pin 22 is provided on the fixed mold 1 and the guide pin receiver 58 into which the guide bin 22 is slidably fitted is provided on 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 may be one set or three or more sets.

According to the optical disk molding die apparatus of the present invention, the height of the inner surface of the information recording portion is 0.02 mm or more (preferably 0.03 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 0.02 mm or more is formed concentrically with the entire optical disc 101. The height h of the convex portion 104 is more preferably 0.03 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 device, not the burr 105 but the convex portion 104 is placed on the turntable 106. 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. The characteristic point of the mold device shown in FIG. 6 is that the depth of 0.02 mm or more (preferably 0.03 m) is formed on the surface of the air blowing 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.

[0042]

Example 1 A TiN film is formed on a resin contact surface (a surface facing a stamper supporting surface) of a movable mold (a mold body on which a stamper supporting surface is not formed) of a mold device by an arc ion plating method. Was vapor-deposited. Specifically, a metallic titanium target is fixed in a vacuum vessel, and a mirror-polished stainless steel disc (180 mmφ × 2) that constitutes a cavity surface that is the opposing surface of the stamper supporting surface is fixed to the opposing surface of the target.
(0 mm thickness) as a substrate, and after decompressing to a vacuum,
By introducing nitrogen gas, 10 ⁻⁴ Torr (13.3 × 10
^-3 Pa). After applying a bias voltage of 1000 V to the substrate to clean the surface by sputtering, an arc discharge of 15 A was generated at a voltage of 20 V on the target to evaporate Ti from the target surface. At that time, a Ti film was vapor-deposited on the substrate surface by applying a bias voltage of 50 V to the substrate. Vapor deposition rate is 1 μm / hr, 2
A TiN film of 2 μm was obtained by vapor deposition for a period of time. It was confirmed from X-ray diffraction that this film was a TiN film.

(Example 2) A TiN film was vapor-deposited on the resin contact surface (the surface facing the stamper supporting surface) of the movable mold (the mold body on which the stamper supporting surface is not formed) of the mold apparatus by the plasma CVD method. . Specifically, in a reaction vessel heated to 500 ° C., a mirror-polished stainless steel disk (18) which constitutes a cavity surface which is an opposite surface of a stamper supporting surface is formed.
(0 mmφ × 20 mm thickness) is used as a substrate, and after degassing to a vacuum, argon gas is introduced and the pressure is 10 ^-2 T.
The substrate was cleaned by applying a high frequency wave of 13.45 MHz of 500 W to the orr (13.3 × 10 ⁻¹ Pa). Then, a mixed gas of hydrogen and argon was added to adjust the pressure to 1 Torr (13.3 × 10 Pa). Then, a mixed gas of TiCl ₄ , hydrogen and nitrogen (volume ratio 1:
50: 5) and 1 Torr (13.3 × 10 Pa)
While adjusting to, a high frequency of 300 W was applied to the substrate to generate plasma and deposit TiN. Vapor deposition rate is 0.5μ
A 1 μm TiN film was obtained by vapor deposition at m / hr for 2 hours.
It was confirmed from X-ray diffraction that this film was a TiN film.

(Embodiments 3 to 5) The resin contact surface (stamper) of the movable die (the die on which the stamper support surface is not formed) of the die apparatus is the same as in Embodiment 1 except that the vapor deposition time is changed. TiN films of various thicknesses were formed on the surface (opposite to the supporting surface).

Example 1 in which the TiN film was formed as described above
The substrates (movable molds) 5 to 5 were mounted in a mold device so that the film forming surface faces the stamper supporting surface of the fixed mold, and injection molding was performed. Table 1 below shows the results of visual observation of the state of the resin contact surface of the substrate (movable type) after 300,000 shots. Also,
As Comparative Example 1, a mirror-polished stainless steel disc (1
80 mmφ × 20 mm thickness), that is, a substrate (movable type) on which a TiN film is not formed on the resin contact surface (opposing surface of the stamper supporting surface) is mounted on the mold device so as to face the fixed stamper supporting surface. Then, injection molding was performed. Table 1 below shows the results of visual observation of the state of the resin contact surface of the substrate (movable type) after 300,000 shots.

[0046] "Table 1"             Film formation on resin contact surface Visual observation results             Film composition and thickness Example 1 TiN film 2 μm No scratch, no peeling, no discoloration, no deposit Example 2 TiN film 1 μm No scratch, no peeling, no discoloration, no deposit Example 3 TiN film 0.5 μm No scratch, no peeling, no discoloration, no deposit Example 4 TiN film 3 μm No scratch, no peeling, no discoloration, no deposit Example 5 TiN film 5 μm No scratch, no peeling, no discoloration, no deposit Comparative Example 1 No coating Small scratches and discoloration on the surface

As shown in Table 1, in the mold device provided with the mold body of Comparative Example 1 in which the TiN film was not formed on the resin contact surface, after the 300,000 shots, the surface of the resin contact surface was finely scratched or discolored. It was observed. On the other hand, the mold apparatus provided with the mold bodies of Examples 1 to 5 in which the TiN film was formed on the resin contact surface and the thickness thereof was in the range of 0.5 μm to 5 μm was 30
Even after 10,000 shots, scratches and peeling of TiN film on the resin contact surface,
No discoloration or deposit was observed, and it was confirmed that it has extremely good durability.

[0048]

As described above in detail, in the optical disk molding die apparatus of the present invention, the resin contact surface of at least one of the first mold body and the second mold body is coated with the TiN film. As a result, it is possible to prevent wear of the mold body due to expansion and contraction due to heating and cooling for each shot, and to effectively prevent mechanical wear when taking out the resin (molded optical disk) solidified by opening the mold. it can. Further, since the TiN film is not corroded by the corrosive gas component accompanying the molten resin, the resin contact surface covered with the TiN film is not roughened. Therefore, according to the optical disk mold apparatus of the present invention, it is possible to suppress the occurrence of surface roughness and minute scratches on the resin contact surface of the mold body, and reduce transfer defects due to surface roughness and minute scratches on the resin contact surface. It is possible to extend the life of the mold.

[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 a conventional optical disk molding die.

[Explanation of symbols]

1 Fixed type (first type body) 2 movable type (second type body) 2a Resin contact surface 2b TiN film 3 Cavity space (product cavity) 10 sprues 17a Stamper support surface 19 Fixed side positioning ring 21 Tapered surface 22 Guide pin (guide member) 36 stamper 37 Claw 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 (7)

[Claims] 1. A first mold body and a second mold body which injection-mold a resin to define a cavity space for molding an optical disk.
And a stamper supporting surface for receiving a stamper for forming irregularities on the optical disk is formed on the first mold body or the second mold body, and the first mold body and the second mold body. A mold apparatus for optical disk molding, wherein at least one resin contact surface of the body is covered with a TiN film. 2. The TiN film has a thickness of 0.5 μm to 5 μm.
The mold apparatus for optical disk molding according to claim 1, wherein the mold apparatus has a range of μm. 3. The optical disk molding die apparatus according to claim 1, wherein the TiN film is formed by a sputtering method. 4. The mold device for optical disk molding according to claim 1, wherein the TiN film is formed by a chemical vapor deposition method. 5. A mold body having the stamper supporting surface,
5. 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. 6. A mold having the stamper supporting surface,
6. The optical disk molding die device according to claim 1, wherein a claw portion for fixing an inner end portion of the stamper is formed. 7. A positioning member provided on opposing surfaces of the first mold body and the second mold body, and having a tapered surface for taper fitting when the mold is closed, and the first mold body and the first mold body. The guide pin provided on one of the two molds and the guide pin on the other mold are provided at positions facing each other, and the guide pin is slidably fitted in the opening / closing direction of the mold. 7. A mold device for optical disk molding according to claim 1, further comprising a guide member having a guide pin receiver.